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1460d7fdc682b980915dadadfd79301b09cc8a75b5bf1c11b74699ff2541d7b7 | from typing import Any, Set
from functools import reduce
from itertools import permutations
from sympy.combinatorics import Permutation
from sympy.core import (
Basic, Expr, Function, diff,
Pow, Mul, Add, Lambda, S, Tuple, Dict
)
from sympy.core.cache import cacheit
from sympy.core.symbol import Symbol, Dummy
from sympy.core.symbol import Str
from sympy.core.sympify import _sympify
from sympy.functions import factorial
from sympy.matrices import ImmutableDenseMatrix as Matrix
from sympy.simplify import simplify
from sympy.solvers import solve
from sympy.utilities.exceptions import SymPyDeprecationWarning
# TODO you are a bit excessive in the use of Dummies
# TODO dummy point, literal field
# TODO too often one needs to call doit or simplify on the output, check the
# tests and find out why
from sympy.tensor.array import ImmutableDenseNDimArray
class Manifold(Basic):
"""
A mathematical manifold.
Explanation
===========
A manifold is a topological space that locally resembles
Euclidean space near each point [1].
This class does not provide any means to study the topological
characteristics of the manifold that it represents, though.
Parameters
==========
name : str
The name of the manifold.
dim : int
The dimension of the manifold.
Examples
========
>>> from sympy.diffgeom import Manifold
>>> m = Manifold('M', 2)
>>> m
M
>>> m.dim
2
References
==========
.. [1] https://en.wikipedia.org/wiki/Manifold
"""
def __new__(cls, name, dim, **kwargs):
if not isinstance(name, Str):
name = Str(name)
dim = _sympify(dim)
obj = super().__new__(cls, name, dim)
obj.patches = _deprecated_list(
"Manifold.patches",
"external container for registry",
19321,
"1.7",
[]
)
return obj
@property
def name(self):
return self.args[0]
@property
def dim(self):
return self.args[1]
class Patch(Basic):
"""
A patch on a manifold.
Explanation
===========
Coordinate patch, or patch in short, is a simply-connected open set around
a point in the manifold [1]. On a manifold one can have many patches that
do not always include the whole manifold. On these patches coordinate
charts can be defined that permit the parameterization of any point on the
patch in terms of a tuple of real numbers (the coordinates).
This class does not provide any means to study the topological
characteristics of the patch that it represents.
Parameters
==========
name : str
The name of the patch.
manifold : Manifold
The manifold on which the patch is defined.
Examples
========
>>> from sympy.diffgeom import Manifold, Patch
>>> m = Manifold('M', 2)
>>> p = Patch('P', m)
>>> p
P
>>> p.dim
2
References
==========
.. [1] G. Sussman, J. Wisdom, W. Farr, Functional Differential Geometry
(2013)
"""
def __new__(cls, name, manifold, **kwargs):
if not isinstance(name, Str):
name = Str(name)
obj = super().__new__(cls, name, manifold)
obj.manifold.patches.append(obj) # deprecated
obj.coord_systems = _deprecated_list(
"Patch.coord_systems",
"external container for registry",
19321,
"1.7",
[]
)
return obj
@property
def name(self):
return self.args[0]
@property
def manifold(self):
return self.args[1]
@property
def dim(self):
return self.manifold.dim
class CoordSystem(Basic):
"""
A coordinate system defined on the patch.
Explanation
===========
Coordinate system is a system that uses one or more coordinates to uniquely
determine the position of the points or other geometric elements on a
manifold [1].
By passing ``Symbols`` to *symbols* parameter, user can define the name and
assumptions of coordinate symbols of the coordinate system. If not passed,
these symbols are generated automatically and are assumed to be real valued.
By passing *relations* parameter, user can define the tranform relations of
coordinate systems. Inverse transformation and indirect transformation can
be found automatically. If this parameter is not passed, coordinate
transformation cannot be done.
Parameters
==========
name : str
The name of the coordinate system.
patch : Patch
The patch where the coordinate system is defined.
symbols : list of Symbols, optional
Defines the names and assumptions of coordinate symbols.
relations : dict, optional
Key is a tuple of two strings, who are the names of the systems where
the coordinates transform from and transform to.
Value is a tuple of the symbols before transformation and a tuple of
the expressions after transformation.
Examples
========
We define two-dimensional Cartesian coordinate system and polar coordinate
system.
>>> from sympy import symbols, pi, sqrt, atan2, cos, sin
>>> from sympy.diffgeom import Manifold, Patch, CoordSystem
>>> m = Manifold('M', 2)
>>> p = Patch('P', m)
>>> x, y = symbols('x y', real=True)
>>> r, theta = symbols('r theta', nonnegative=True)
>>> relation_dict = {
... ('Car2D', 'Pol'): [(x, y), (sqrt(x**2 + y**2), atan2(y, x))],
... ('Pol', 'Car2D'): [(r, theta), (r*cos(theta), r*sin(theta))]
... }
>>> Car2D = CoordSystem('Car2D', p, (x, y), relation_dict)
>>> Pol = CoordSystem('Pol', p, (r, theta), relation_dict)
``symbols`` property returns ``CoordinateSymbol`` instances. These symbols
are not same with the symbols used to construct the coordinate system.
>>> Car2D
Car2D
>>> Car2D.dim
2
>>> Car2D.symbols
(x, y)
>>> _[0].func
<class 'sympy.diffgeom.diffgeom.CoordinateSymbol'>
``transformation()`` method returns the transformation function from
one coordinate system to another. ``transform()`` method returns the
transformed coordinates.
>>> Car2D.transformation(Pol)
Lambda((x, y), Matrix([
[sqrt(x**2 + y**2)],
[ atan2(y, x)]]))
>>> Car2D.transform(Pol)
Matrix([
[sqrt(x**2 + y**2)],
[ atan2(y, x)]])
>>> Car2D.transform(Pol, [1, 2])
Matrix([
[sqrt(5)],
[atan(2)]])
``jacobian()`` method returns the Jacobian matrix of coordinate
transformation between two systems. ``jacobian_determinant()`` method
returns the Jacobian determinant of coordinate transformation between two
systems.
>>> Pol.jacobian(Car2D)
Matrix([
[cos(theta), -r*sin(theta)],
[sin(theta), r*cos(theta)]])
>>> Pol.jacobian(Car2D, [1, pi/2])
Matrix([
[0, -1],
[1, 0]])
>>> Car2D.jacobian_determinant(Pol)
1/sqrt(x**2 + y**2)
>>> Car2D.jacobian_determinant(Pol, [1,0])
1
References
==========
.. [1] https://en.wikipedia.org/wiki/Coordinate_system
"""
def __new__(cls, name, patch, symbols=None, relations={}, **kwargs):
if not isinstance(name, Str):
name = Str(name)
# canonicallize the symbols
if symbols is None:
names = kwargs.get('names', None)
if names is None:
symbols = Tuple(
*[Symbol('%s_%s' % (name.name, i), real=True)
for i in range(patch.dim)]
)
else:
SymPyDeprecationWarning(
feature="Class signature 'names' of CoordSystem",
useinstead="class signature 'symbols'",
issue=19321,
deprecated_since_version="1.7"
).warn()
symbols = Tuple(
*[Symbol(n, real=True) for n in names]
)
else:
syms = []
for s in symbols:
if isinstance(s, Symbol):
syms.append(Symbol(s.name, **s._assumptions.generator))
elif isinstance(s, str):
SymPyDeprecationWarning(
feature="Passing str as coordinate symbol's name",
useinstead="Symbol which contains the name and assumption for coordinate symbol",
issue=19321,
deprecated_since_version="1.7"
).warn()
syms.append(Symbol(s, real=True))
symbols = Tuple(*syms)
# canonicallize the relations
rel_temp = {}
for k,v in relations.items():
s1, s2 = k
if not isinstance(s1, Str):
s1 = Str(s1)
if not isinstance(s2, Str):
s2 = Str(s2)
key = Tuple(s1, s2)
# Old version used Lambda as a value.
if isinstance(v, Lambda):
v = (tuple(v.signature), tuple(v.expr))
else:
v = (tuple(v[0]), tuple(v[1]))
rel_temp[key] = v
relations = Dict(rel_temp)
# construct the object
obj = super().__new__(cls, name, patch, symbols, relations)
# Add deprecated attributes
obj.transforms = _deprecated_dict(
"Mutable CoordSystem.transforms",
"'relations' parameter in class signature",
19321,
"1.7",
{}
)
obj._names = [str(n) for n in symbols]
obj.patch.coord_systems.append(obj) # deprecated
obj._dummies = [Dummy(str(n)) for n in symbols] # deprecated
obj._dummy = Dummy()
return obj
@property
def name(self):
return self.args[0]
@property
def patch(self):
return self.args[1]
@property
def manifold(self):
return self.patch.manifold
@property
def symbols(self):
return tuple(CoordinateSymbol(self, i, **s._assumptions.generator)
for i,s in enumerate(self.args[2]))
@property
def relations(self):
return self.args[3]
@property
def dim(self):
return self.patch.dim
##########################################################################
# Finding transformation relation
##########################################################################
def transformation(self, sys):
"""
Return coordinate transformation function from *self* to *sys*.
Parameters
==========
sys : CoordSystem
Returns
=======
sympy.Lambda
Examples
========
>>> from sympy.diffgeom.rn import R2_r, R2_p
>>> R2_r.transformation(R2_p)
Lambda((x, y), Matrix([
[sqrt(x**2 + y**2)],
[ atan2(y, x)]]))
"""
signature = self.args[2]
key = Tuple(self.name, sys.name)
if self == sys:
expr = Matrix(self.symbols)
elif key in self.relations:
expr = Matrix(self.relations[key][1])
elif key[::-1] in self.relations:
expr = Matrix(self._inverse_transformation(sys, self))
else:
expr = Matrix(self._indirect_transformation(self, sys))
return Lambda(signature, expr)
@staticmethod
def _solve_inverse(sym1, sym2, exprs, sys1_name, sys2_name):
ret = solve(
[t[0] - t[1] for t in zip(sym2, exprs)],
list(sym1), dict=True)
if len(ret) == 0:
temp = "Cannot solve inverse relation from {} to {}."
raise NotImplementedError(temp.format(sys1_name, sys2_name))
elif len(ret) > 1:
temp = "Obtained multiple inverse relation from {} to {}."
raise ValueError(temp.format(sys1_name, sys2_name))
return ret[0]
@classmethod
def _inverse_transformation(cls, sys1, sys2):
# Find the transformation relation from sys2 to sys1
forward = sys1.transform(sys2)
inv_results = cls._solve_inverse(sys1.symbols, sys2.symbols, forward,
sys1.name, sys2.name)
signature = tuple(sys1.symbols)
return [inv_results[s] for s in signature]
@classmethod
@cacheit
def _indirect_transformation(cls, sys1, sys2):
# Find the transformation relation between two indirectly connected
# coordinate systems
rel = sys1.relations
path = cls._dijkstra(sys1, sys2)
transforms = []
for s1, s2 in zip(path, path[1:]):
if (s1, s2) in rel:
transforms.append(rel[(s1, s2)])
else:
sym2, inv_exprs = rel[(s2, s1)]
sym1 = tuple(Dummy() for i in sym2)
ret = cls._solve_inverse(sym2, sym1, inv_exprs, s2, s1)
ret = tuple(ret[s] for s in sym2)
transforms.append((sym1, ret))
syms = sys1.args[2]
exprs = syms
for newsyms, newexprs in transforms:
exprs = tuple(e.subs(zip(newsyms, exprs)) for e in newexprs)
return exprs
@staticmethod
def _dijkstra(sys1, sys2):
# Use Dijkstra algorithm to find the shortest path between two indirectly-connected
# coordinate systems
# return value is the list of the names of the systems.
relations = sys1.relations
graph = {}
for s1, s2 in relations.keys():
if s1 not in graph:
graph[s1] = {s2}
else:
graph[s1].add(s2)
if s2 not in graph:
graph[s2] = {s1}
else:
graph[s2].add(s1)
path_dict = {sys:[0, [], 0] for sys in graph} # minimum distance, path, times of visited
def visit(sys):
path_dict[sys][2] = 1
for newsys in graph[sys]:
distance = path_dict[sys][0] + 1
if path_dict[newsys][0] >= distance or not path_dict[newsys][1]:
path_dict[newsys][0] = distance
path_dict[newsys][1] = [i for i in path_dict[sys][1]]
path_dict[newsys][1].append(sys)
visit(sys1.name)
while True:
min_distance = max(path_dict.values(), key=lambda x:x[0])[0]
newsys = None
for sys, lst in path_dict.items():
if 0 < lst[0] <= min_distance and not lst[2]:
min_distance = lst[0]
newsys = sys
if newsys is None:
break
visit(newsys)
result = path_dict[sys2.name][1]
result.append(sys2.name)
if result == [sys2.name]:
raise KeyError("Two coordinate systems are not connected.")
return result
def connect_to(self, to_sys, from_coords, to_exprs, inverse=True, fill_in_gaps=False):
SymPyDeprecationWarning(
feature="CoordSystem.connect_to",
useinstead="new instance generated with new 'transforms' parameter",
issue=19321,
deprecated_since_version="1.7"
).warn()
from_coords, to_exprs = dummyfy(from_coords, to_exprs)
self.transforms[to_sys] = Matrix(from_coords), Matrix(to_exprs)
if inverse:
to_sys.transforms[self] = self._inv_transf(from_coords, to_exprs)
if fill_in_gaps:
self._fill_gaps_in_transformations()
@staticmethod
def _inv_transf(from_coords, to_exprs):
# Will be removed when connect_to is removed
inv_from = [i.as_dummy() for i in from_coords]
inv_to = solve(
[t[0] - t[1] for t in zip(inv_from, to_exprs)],
list(from_coords), dict=True)[0]
inv_to = [inv_to[fc] for fc in from_coords]
return Matrix(inv_from), Matrix(inv_to)
@staticmethod
def _fill_gaps_in_transformations():
# Will be removed when connect_to is removed
raise NotImplementedError
##########################################################################
# Coordinate transformations
##########################################################################
def transform(self, sys, coordinates=None):
"""
Return the result of coordinate transformation from *self* to *sys*.
If coordinates are not given, coordinate symbols of *self* are used.
Parameters
==========
sys : CoordSystem
coordinates : Any iterable, optional.
Returns
=======
sympy.ImmutableDenseMatrix containing CoordinateSymbol
Examples
========
>>> from sympy.diffgeom.rn import R2_r, R2_p
>>> R2_r.transform(R2_p)
Matrix([
[sqrt(x**2 + y**2)],
[ atan2(y, x)]])
>>> R2_r.transform(R2_p, [0, 1])
Matrix([
[ 1],
[pi/2]])
"""
if coordinates is None:
coordinates = self.symbols
if self != sys:
transf = self.transformation(sys)
coordinates = transf(*coordinates)
else:
coordinates = Matrix(coordinates)
return coordinates
def coord_tuple_transform_to(self, to_sys, coords):
"""Transform ``coords`` to coord system ``to_sys``."""
SymPyDeprecationWarning(
feature="CoordSystem.coord_tuple_transform_to",
useinstead="CoordSystem.transform",
issue=19321,
deprecated_since_version="1.7"
).warn()
coords = Matrix(coords)
if self != to_sys:
transf = self.transforms[to_sys]
coords = transf[1].subs(list(zip(transf[0], coords)))
return coords
def jacobian(self, sys, coordinates=None):
"""
Return the jacobian matrix of a transformation on given coordinates.
If coordinates are not given, coordinate symbols of *self* are used.
Parameters
==========
sys : CoordSystem
coordinates : Any iterable, optional.
Returns
=======
sympy.ImmutableDenseMatrix
Examples
========
>>> from sympy.diffgeom.rn import R2_r, R2_p
>>> R2_p.jacobian(R2_r)
Matrix([
[cos(theta), -rho*sin(theta)],
[sin(theta), rho*cos(theta)]])
>>> R2_p.jacobian(R2_r, [1, 0])
Matrix([
[1, 0],
[0, 1]])
"""
result = self.transform(sys).jacobian(self.symbols)
if coordinates is not None:
result = result.subs(list(zip(self.symbols, coordinates)))
return result
jacobian_matrix = jacobian
def jacobian_determinant(self, sys, coordinates=None):
"""
Return the jacobian determinant of a transformation on given
coordinates. If coordinates are not given, coordinate symbols of *self*
are used.
Parameters
==========
sys : CoordSystem
coordinates : Any iterable, optional.
Returns
=======
sympy.Expr
Examples
========
>>> from sympy.diffgeom.rn import R2_r, R2_p
>>> R2_r.jacobian_determinant(R2_p)
1/sqrt(x**2 + y**2)
>>> R2_r.jacobian_determinant(R2_p, [1, 0])
1
"""
return self.jacobian(sys, coordinates).det()
##########################################################################
# Points
##########################################################################
def point(self, coords):
"""Create a ``Point`` with coordinates given in this coord system."""
return Point(self, coords)
def point_to_coords(self, point):
"""Calculate the coordinates of a point in this coord system."""
return point.coords(self)
##########################################################################
# Base fields.
##########################################################################
def base_scalar(self, coord_index):
"""Return ``BaseScalarField`` that takes a point and returns one of the coordinates."""
return BaseScalarField(self, coord_index)
coord_function = base_scalar
def base_scalars(self):
"""Returns a list of all coordinate functions.
For more details see the ``base_scalar`` method of this class."""
return [self.base_scalar(i) for i in range(self.dim)]
coord_functions = base_scalars
def base_vector(self, coord_index):
"""Return a basis vector field.
The basis vector field for this coordinate system. It is also an
operator on scalar fields."""
return BaseVectorField(self, coord_index)
def base_vectors(self):
"""Returns a list of all base vectors.
For more details see the ``base_vector`` method of this class."""
return [self.base_vector(i) for i in range(self.dim)]
def base_oneform(self, coord_index):
"""Return a basis 1-form field.
The basis one-form field for this coordinate system. It is also an
operator on vector fields."""
return Differential(self.coord_function(coord_index))
def base_oneforms(self):
"""Returns a list of all base oneforms.
For more details see the ``base_oneform`` method of this class."""
return [self.base_oneform(i) for i in range(self.dim)]
class CoordinateSymbol(Symbol):
"""A symbol which denotes an abstract value of i-th coordinate of
the coordinate system with given context.
Explanation
===========
Each coordinates in coordinate system are represented by unique symbol,
such as x, y, z in Cartesian coordinate system.
You may not construct this class directly. Instead, use `symbols` method
of CoordSystem.
Parameters
==========
coord_sys : CoordSystem
index : integer
Examples
========
>>> from sympy import symbols, Lambda, Matrix, sqrt, atan2, cos, sin
>>> from sympy.diffgeom import Manifold, Patch, CoordSystem
>>> m = Manifold('M', 2)
>>> p = Patch('P', m)
>>> x, y = symbols('x y', real=True)
>>> r, theta = symbols('r theta', nonnegative=True)
>>> relation_dict = {
... ('Car2D', 'Pol'): Lambda((x, y), Matrix([sqrt(x**2 + y**2), atan2(y, x)])),
... ('Pol', 'Car2D'): Lambda((r, theta), Matrix([r*cos(theta), r*sin(theta)]))
... }
>>> Car2D = CoordSystem('Car2D', p, [x, y], relation_dict)
>>> Pol = CoordSystem('Pol', p, [r, theta], relation_dict)
>>> x, y = Car2D.symbols
``CoordinateSymbol`` contains its coordinate symbol and index.
>>> x.name
'x'
>>> x.coord_sys == Car2D
True
>>> x.index
0
>>> x.is_real
True
You can transform ``CoordinateSymbol`` into other coordinate system using
``rewrite()`` method.
>>> x.rewrite(Pol)
r*cos(theta)
>>> sqrt(x**2 + y**2).rewrite(Pol).simplify()
r
"""
def __new__(cls, coord_sys, index, **assumptions):
name = coord_sys.args[2][index].name
obj = super().__new__(cls, name, **assumptions)
obj.coord_sys = coord_sys
obj.index = index
return obj
def __getnewargs__(self):
return (self.coord_sys, self.index)
def _hashable_content(self):
return (
self.coord_sys, self.index
) + tuple(sorted(self.assumptions0.items()))
def _eval_rewrite(self, rule, args, **hints):
if isinstance(rule, CoordSystem):
return rule.transform(self.coord_sys)[self.index]
return super()._eval_rewrite(rule, args, **hints)
class Point(Basic):
"""Point defined in a coordinate system.
Explanation
===========
Mathematically, point is defined in the manifold and does not have any coordinates
by itself. Coordinate system is what imbues the coordinates to the point by coordinate
chart. However, due to the difficulty of realizing such logic, you must supply
a coordinate system and coordinates to define a Point here.
The usage of this object after its definition is independent of the
coordinate system that was used in order to define it, however due to
limitations in the simplification routines you can arrive at complicated
expressions if you use inappropriate coordinate systems.
Parameters
==========
coord_sys : CoordSystem
coords : list
The coordinates of the point.
Examples
========
>>> from sympy import pi
>>> from sympy.diffgeom import Point
>>> from sympy.diffgeom.rn import R2, R2_r, R2_p
>>> rho, theta = R2_p.symbols
>>> p = Point(R2_p, [rho, 3*pi/4])
>>> p.manifold == R2
True
>>> p.coords()
Matrix([
[ rho],
[3*pi/4]])
>>> p.coords(R2_r)
Matrix([
[-sqrt(2)*rho/2],
[ sqrt(2)*rho/2]])
"""
def __new__(cls, coord_sys, coords, **kwargs):
coords = Matrix(coords)
obj = super().__new__(cls, coord_sys, coords)
obj._coord_sys = coord_sys
obj._coords = coords
return obj
@property
def patch(self):
return self._coord_sys.patch
@property
def manifold(self):
return self._coord_sys.manifold
@property
def dim(self):
return self.manifold.dim
def coords(self, sys=None):
"""
Coordinates of the point in given coordinate system. If coordinate system
is not passed, it returns the coordinates in the coordinate system in which
the poin was defined.
"""
if sys is None:
return self._coords
else:
return self._coord_sys.transform(sys, self._coords)
@property
def free_symbols(self):
return self._coords.free_symbols
class BaseScalarField(Expr):
"""Base scalar field over a manifold for a given coordinate system.
Explanation
===========
A scalar field takes a point as an argument and returns a scalar.
A base scalar field of a coordinate system takes a point and returns one of
the coordinates of that point in the coordinate system in question.
To define a scalar field you need to choose the coordinate system and the
index of the coordinate.
The use of the scalar field after its definition is independent of the
coordinate system in which it was defined, however due to limitations in
the simplification routines you may arrive at more complicated
expression if you use unappropriate coordinate systems.
You can build complicated scalar fields by just building up SymPy
expressions containing ``BaseScalarField`` instances.
Parameters
==========
coord_sys : CoordSystem
index : integer
Examples
========
>>> from sympy import Function, pi
>>> from sympy.diffgeom import BaseScalarField
>>> from sympy.diffgeom.rn import R2_r, R2_p
>>> rho, _ = R2_p.symbols
>>> point = R2_p.point([rho, 0])
>>> fx, fy = R2_r.base_scalars()
>>> ftheta = BaseScalarField(R2_r, 1)
>>> fx(point)
rho
>>> fy(point)
0
>>> (fx**2+fy**2).rcall(point)
rho**2
>>> g = Function('g')
>>> fg = g(ftheta-pi)
>>> fg.rcall(point)
g(-pi)
"""
is_commutative = True
def __new__(cls, coord_sys, index, **kwargs):
index = _sympify(index)
obj = super().__new__(cls, coord_sys, index)
obj._coord_sys = coord_sys
obj._index = index
return obj
@property
def coord_sys(self):
return self.args[0]
@property
def index(self):
return self.args[1]
@property
def patch(self):
return self.coord_sys.patch
@property
def manifold(self):
return self.coord_sys.manifold
@property
def dim(self):
return self.manifold.dim
def __call__(self, *args):
"""Evaluating the field at a point or doing nothing.
If the argument is a ``Point`` instance, the field is evaluated at that
point. The field is returned itself if the argument is any other
object. It is so in order to have working recursive calling mechanics
for all fields (check the ``__call__`` method of ``Expr``).
"""
point = args[0]
if len(args) != 1 or not isinstance(point, Point):
return self
coords = point.coords(self._coord_sys)
# XXX Calling doit is necessary with all the Subs expressions
# XXX Calling simplify is necessary with all the trig expressions
return simplify(coords[self._index]).doit()
# XXX Workaround for limitations on the content of args
free_symbols = set() # type: Set[Any]
def doit(self):
return self
class BaseVectorField(Expr):
r"""Base vector field over a manifold for a given coordinate system.
Explanation
===========
A vector field is an operator taking a scalar field and returning a
directional derivative (which is also a scalar field).
A base vector field is the same type of operator, however the derivation is
specifically done with respect to a chosen coordinate.
To define a base vector field you need to choose the coordinate system and
the index of the coordinate.
The use of the vector field after its definition is independent of the
coordinate system in which it was defined, however due to limitations in the
simplification routines you may arrive at more complicated expression if you
use unappropriate coordinate systems.
Parameters
==========
coord_sys : CoordSystem
index : integer
Examples
========
>>> from sympy import Function
>>> from sympy.diffgeom.rn import R2_p, R2_r
>>> from sympy.diffgeom import BaseVectorField
>>> from sympy import pprint
>>> x, y = R2_r.symbols
>>> rho, theta = R2_p.symbols
>>> fx, fy = R2_r.base_scalars()
>>> point_p = R2_p.point([rho, theta])
>>> point_r = R2_r.point([x, y])
>>> g = Function('g')
>>> s_field = g(fx, fy)
>>> v = BaseVectorField(R2_r, 1)
>>> pprint(v(s_field))
/ d \|
|---(g(x, xi))||
\dxi /|xi=y
>>> pprint(v(s_field).rcall(point_r).doit())
d
--(g(x, y))
dy
>>> pprint(v(s_field).rcall(point_p))
/ d \|
|---(g(rho*cos(theta), xi))||
\dxi /|xi=rho*sin(theta)
"""
is_commutative = False
def __new__(cls, coord_sys, index, **kwargs):
index = _sympify(index)
obj = super().__new__(cls, coord_sys, index)
obj._coord_sys = coord_sys
obj._index = index
return obj
@property
def coord_sys(self):
return self.args[0]
@property
def index(self):
return self.args[1]
@property
def patch(self):
return self.coord_sys.patch
@property
def manifold(self):
return self.coord_sys.manifold
@property
def dim(self):
return self.manifold.dim
def __call__(self, scalar_field):
"""Apply on a scalar field.
The action of a vector field on a scalar field is a directional
differentiation.
If the argument is not a scalar field an error is raised.
"""
if covariant_order(scalar_field) or contravariant_order(scalar_field):
raise ValueError('Only scalar fields can be supplied as arguments to vector fields.')
if scalar_field is None:
return self
base_scalars = list(scalar_field.atoms(BaseScalarField))
# First step: e_x(x+r**2) -> e_x(x) + 2*r*e_x(r)
d_var = self._coord_sys._dummy
# TODO: you need a real dummy function for the next line
d_funcs = [Function('_#_%s' % i)(d_var) for i,
b in enumerate(base_scalars)]
d_result = scalar_field.subs(list(zip(base_scalars, d_funcs)))
d_result = d_result.diff(d_var)
# Second step: e_x(x) -> 1 and e_x(r) -> cos(atan2(x, y))
coords = self._coord_sys.symbols
d_funcs_deriv = [f.diff(d_var) for f in d_funcs]
d_funcs_deriv_sub = []
for b in base_scalars:
jac = self._coord_sys.jacobian(b._coord_sys, coords)
d_funcs_deriv_sub.append(jac[b._index, self._index])
d_result = d_result.subs(list(zip(d_funcs_deriv, d_funcs_deriv_sub)))
# Remove the dummies
result = d_result.subs(list(zip(d_funcs, base_scalars)))
result = result.subs(list(zip(coords, self._coord_sys.coord_functions())))
return result.doit()
def _find_coords(expr):
# Finds CoordinateSystems existing in expr
fields = expr.atoms(BaseScalarField, BaseVectorField)
result = set()
for f in fields:
result.add(f._coord_sys)
return result
class Commutator(Expr):
r"""Commutator of two vector fields.
Explanation
===========
The commutator of two vector fields `v_1` and `v_2` is defined as the
vector field `[v_1, v_2]` that evaluated on each scalar field `f` is equal
to `v_1(v_2(f)) - v_2(v_1(f))`.
Examples
========
>>> from sympy.diffgeom.rn import R2_p, R2_r
>>> from sympy.diffgeom import Commutator
>>> from sympy.simplify import simplify
>>> fx, fy = R2_r.base_scalars()
>>> e_x, e_y = R2_r.base_vectors()
>>> e_r = R2_p.base_vector(0)
>>> c_xy = Commutator(e_x, e_y)
>>> c_xr = Commutator(e_x, e_r)
>>> c_xy
0
Unfortunately, the current code is not able to compute everything:
>>> c_xr
Commutator(e_x, e_rho)
>>> simplify(c_xr(fy**2))
-2*cos(theta)*y**2/(x**2 + y**2)
"""
def __new__(cls, v1, v2):
if (covariant_order(v1) or contravariant_order(v1) != 1
or covariant_order(v2) or contravariant_order(v2) != 1):
raise ValueError(
'Only commutators of vector fields are supported.')
if v1 == v2:
return S.Zero
coord_sys = set().union(*[_find_coords(v) for v in (v1, v2)])
if len(coord_sys) == 1:
# Only one coordinate systems is used, hence it is easy enough to
# actually evaluate the commutator.
if all(isinstance(v, BaseVectorField) for v in (v1, v2)):
return S.Zero
bases_1, bases_2 = [list(v.atoms(BaseVectorField))
for v in (v1, v2)]
coeffs_1 = [v1.expand().coeff(b) for b in bases_1]
coeffs_2 = [v2.expand().coeff(b) for b in bases_2]
res = 0
for c1, b1 in zip(coeffs_1, bases_1):
for c2, b2 in zip(coeffs_2, bases_2):
res += c1*b1(c2)*b2 - c2*b2(c1)*b1
return res
else:
obj = super().__new__(cls, v1, v2)
obj._v1 = v1 # deprecated assignment
obj._v2 = v2 # deprecated assignment
return obj
@property
def v1(self):
return self.args[0]
@property
def v2(self):
return self.args[1]
def __call__(self, scalar_field):
"""Apply on a scalar field.
If the argument is not a scalar field an error is raised.
"""
return self.v1(self.v2(scalar_field)) - self.v2(self.v1(scalar_field))
class Differential(Expr):
r"""Return the differential (exterior derivative) of a form field.
Explanation
===========
The differential of a form (i.e. the exterior derivative) has a complicated
definition in the general case.
The differential `df` of the 0-form `f` is defined for any vector field `v`
as `df(v) = v(f)`.
Examples
========
>>> from sympy import Function
>>> from sympy.diffgeom.rn import R2_r
>>> from sympy.diffgeom import Differential
>>> from sympy import pprint
>>> fx, fy = R2_r.base_scalars()
>>> e_x, e_y = R2_r.base_vectors()
>>> g = Function('g')
>>> s_field = g(fx, fy)
>>> dg = Differential(s_field)
>>> dg
d(g(x, y))
>>> pprint(dg(e_x))
/ d \|
|---(g(xi, y))||
\dxi /|xi=x
>>> pprint(dg(e_y))
/ d \|
|---(g(x, xi))||
\dxi /|xi=y
Applying the exterior derivative operator twice always results in:
>>> Differential(dg)
0
"""
is_commutative = False
def __new__(cls, form_field):
if contravariant_order(form_field):
raise ValueError(
'A vector field was supplied as an argument to Differential.')
if isinstance(form_field, Differential):
return S.Zero
else:
obj = super().__new__(cls, form_field)
obj._form_field = form_field # deprecated assignment
return obj
@property
def form_field(self):
return self.args[0]
def __call__(self, *vector_fields):
"""Apply on a list of vector_fields.
Explanation
===========
If the number of vector fields supplied is not equal to 1 + the order of
the form field inside the differential the result is undefined.
For 1-forms (i.e. differentials of scalar fields) the evaluation is
done as `df(v)=v(f)`. However if `v` is ``None`` instead of a vector
field, the differential is returned unchanged. This is done in order to
permit partial contractions for higher forms.
In the general case the evaluation is done by applying the form field
inside the differential on a list with one less elements than the number
of elements in the original list. Lowering the number of vector fields
is achieved through replacing each pair of fields by their
commutator.
If the arguments are not vectors or ``None``s an error is raised.
"""
if any((contravariant_order(a) != 1 or covariant_order(a)) and a is not None
for a in vector_fields):
raise ValueError('The arguments supplied to Differential should be vector fields or Nones.')
k = len(vector_fields)
if k == 1:
if vector_fields[0]:
return vector_fields[0].rcall(self._form_field)
return self
else:
# For higher form it is more complicated:
# Invariant formula:
# https://en.wikipedia.org/wiki/Exterior_derivative#Invariant_formula
# df(v1, ... vn) = +/- vi(f(v1..no i..vn))
# +/- f([vi,vj],v1..no i, no j..vn)
f = self._form_field
v = vector_fields
ret = 0
for i in range(k):
t = v[i].rcall(f.rcall(*v[:i] + v[i + 1:]))
ret += (-1)**i*t
for j in range(i + 1, k):
c = Commutator(v[i], v[j])
if c: # TODO this is ugly - the Commutator can be Zero and
# this causes the next line to fail
t = f.rcall(*(c,) + v[:i] + v[i + 1:j] + v[j + 1:])
ret += (-1)**(i + j)*t
return ret
class TensorProduct(Expr):
"""Tensor product of forms.
Explanation
===========
The tensor product permits the creation of multilinear functionals (i.e.
higher order tensors) out of lower order fields (e.g. 1-forms and vector
fields). However, the higher tensors thus created lack the interesting
features provided by the other type of product, the wedge product, namely
they are not antisymmetric and hence are not form fields.
Examples
========
>>> from sympy.diffgeom.rn import R2_r
>>> from sympy.diffgeom import TensorProduct
>>> fx, fy = R2_r.base_scalars()
>>> e_x, e_y = R2_r.base_vectors()
>>> dx, dy = R2_r.base_oneforms()
>>> TensorProduct(dx, dy)(e_x, e_y)
1
>>> TensorProduct(dx, dy)(e_y, e_x)
0
>>> TensorProduct(dx, fx*dy)(fx*e_x, e_y)
x**2
>>> TensorProduct(e_x, e_y)(fx**2, fy**2)
4*x*y
>>> TensorProduct(e_y, dx)(fy)
dx
You can nest tensor products.
>>> tp1 = TensorProduct(dx, dy)
>>> TensorProduct(tp1, dx)(e_x, e_y, e_x)
1
You can make partial contraction for instance when 'raising an index'.
Putting ``None`` in the second argument of ``rcall`` means that the
respective position in the tensor product is left as it is.
>>> TP = TensorProduct
>>> metric = TP(dx, dx) + 3*TP(dy, dy)
>>> metric.rcall(e_y, None)
3*dy
Or automatically pad the args with ``None`` without specifying them.
>>> metric.rcall(e_y)
3*dy
"""
def __new__(cls, *args):
scalar = Mul(*[m for m in args if covariant_order(m) + contravariant_order(m) == 0])
multifields = [m for m in args if covariant_order(m) + contravariant_order(m)]
if multifields:
if len(multifields) == 1:
return scalar*multifields[0]
return scalar*super().__new__(cls, *multifields)
else:
return scalar
def __call__(self, *fields):
"""Apply on a list of fields.
If the number of input fields supplied is not equal to the order of
the tensor product field, the list of arguments is padded with ``None``'s.
The list of arguments is divided in sublists depending on the order of
the forms inside the tensor product. The sublists are provided as
arguments to these forms and the resulting expressions are given to the
constructor of ``TensorProduct``.
"""
tot_order = covariant_order(self) + contravariant_order(self)
tot_args = len(fields)
if tot_args != tot_order:
fields = list(fields) + [None]*(tot_order - tot_args)
orders = [covariant_order(f) + contravariant_order(f) for f in self._args]
indices = [sum(orders[:i + 1]) for i in range(len(orders) - 1)]
fields = [fields[i:j] for i, j in zip([0] + indices, indices + [None])]
multipliers = [t[0].rcall(*t[1]) for t in zip(self._args, fields)]
return TensorProduct(*multipliers)
class WedgeProduct(TensorProduct):
"""Wedge product of forms.
Explanation
===========
In the context of integration only completely antisymmetric forms make
sense. The wedge product permits the creation of such forms.
Examples
========
>>> from sympy.diffgeom.rn import R2_r
>>> from sympy.diffgeom import WedgeProduct
>>> fx, fy = R2_r.base_scalars()
>>> e_x, e_y = R2_r.base_vectors()
>>> dx, dy = R2_r.base_oneforms()
>>> WedgeProduct(dx, dy)(e_x, e_y)
1
>>> WedgeProduct(dx, dy)(e_y, e_x)
-1
>>> WedgeProduct(dx, fx*dy)(fx*e_x, e_y)
x**2
>>> WedgeProduct(e_x, e_y)(fy, None)
-e_x
You can nest wedge products.
>>> wp1 = WedgeProduct(dx, dy)
>>> WedgeProduct(wp1, dx)(e_x, e_y, e_x)
0
"""
# TODO the calculation of signatures is slow
# TODO you do not need all these permutations (neither the prefactor)
def __call__(self, *fields):
"""Apply on a list of vector_fields.
The expression is rewritten internally in terms of tensor products and evaluated."""
orders = (covariant_order(e) + contravariant_order(e) for e in self.args)
mul = 1/Mul(*(factorial(o) for o in orders))
perms = permutations(fields)
perms_par = (Permutation(
p).signature() for p in permutations(list(range(len(fields)))))
tensor_prod = TensorProduct(*self.args)
return mul*Add(*[tensor_prod(*p[0])*p[1] for p in zip(perms, perms_par)])
class LieDerivative(Expr):
"""Lie derivative with respect to a vector field.
Explanation
===========
The transport operator that defines the Lie derivative is the pushforward of
the field to be derived along the integral curve of the field with respect
to which one derives.
Examples
========
>>> from sympy.diffgeom.rn import R2_r, R2_p
>>> from sympy.diffgeom import (LieDerivative, TensorProduct)
>>> fx, fy = R2_r.base_scalars()
>>> e_x, e_y = R2_r.base_vectors()
>>> e_rho, e_theta = R2_p.base_vectors()
>>> dx, dy = R2_r.base_oneforms()
>>> LieDerivative(e_x, fy)
0
>>> LieDerivative(e_x, fx)
1
>>> LieDerivative(e_x, e_x)
0
The Lie derivative of a tensor field by another tensor field is equal to
their commutator:
>>> LieDerivative(e_x, e_rho)
Commutator(e_x, e_rho)
>>> LieDerivative(e_x + e_y, fx)
1
>>> tp = TensorProduct(dx, dy)
>>> LieDerivative(e_x, tp)
LieDerivative(e_x, TensorProduct(dx, dy))
>>> LieDerivative(e_x, tp)
LieDerivative(e_x, TensorProduct(dx, dy))
"""
def __new__(cls, v_field, expr):
expr_form_ord = covariant_order(expr)
if contravariant_order(v_field) != 1 or covariant_order(v_field):
raise ValueError('Lie derivatives are defined only with respect to'
' vector fields. The supplied argument was not a '
'vector field.')
if expr_form_ord > 0:
obj = super().__new__(cls, v_field, expr)
# deprecated assignments
obj._v_field = v_field
obj._expr = expr
return obj
if expr.atoms(BaseVectorField):
return Commutator(v_field, expr)
else:
return v_field.rcall(expr)
@property
def v_field(self):
return self.args[0]
@property
def expr(self):
return self.args[1]
def __call__(self, *args):
v = self.v_field
expr = self.expr
lead_term = v(expr(*args))
rest = Add(*[Mul(*args[:i] + (Commutator(v, args[i]),) + args[i + 1:])
for i in range(len(args))])
return lead_term - rest
class BaseCovarDerivativeOp(Expr):
"""Covariant derivative operator with respect to a base vector.
Examples
========
>>> from sympy.diffgeom.rn import R2_r
>>> from sympy.diffgeom import BaseCovarDerivativeOp
>>> from sympy.diffgeom import metric_to_Christoffel_2nd, TensorProduct
>>> TP = TensorProduct
>>> fx, fy = R2_r.base_scalars()
>>> e_x, e_y = R2_r.base_vectors()
>>> dx, dy = R2_r.base_oneforms()
>>> ch = metric_to_Christoffel_2nd(TP(dx, dx) + TP(dy, dy))
>>> ch
[[[0, 0], [0, 0]], [[0, 0], [0, 0]]]
>>> cvd = BaseCovarDerivativeOp(R2_r, 0, ch)
>>> cvd(fx)
1
>>> cvd(fx*e_x)
e_x
"""
def __new__(cls, coord_sys, index, christoffel):
index = _sympify(index)
christoffel = ImmutableDenseNDimArray(christoffel)
obj = super().__new__(cls, coord_sys, index, christoffel)
# deprecated assignments
obj._coord_sys = coord_sys
obj._index = index
obj._christoffel = christoffel
return obj
@property
def coord_sys(self):
return self.args[0]
@property
def index(self):
return self.args[1]
@property
def christoffel(self):
return self.args[2]
def __call__(self, field):
"""Apply on a scalar field.
The action of a vector field on a scalar field is a directional
differentiation.
If the argument is not a scalar field the behaviour is undefined.
"""
if covariant_order(field) != 0:
raise NotImplementedError()
field = vectors_in_basis(field, self._coord_sys)
wrt_vector = self._coord_sys.base_vector(self._index)
wrt_scalar = self._coord_sys.coord_function(self._index)
vectors = list(field.atoms(BaseVectorField))
# First step: replace all vectors with something susceptible to
# derivation and do the derivation
# TODO: you need a real dummy function for the next line
d_funcs = [Function('_#_%s' % i)(wrt_scalar) for i,
b in enumerate(vectors)]
d_result = field.subs(list(zip(vectors, d_funcs)))
d_result = wrt_vector(d_result)
# Second step: backsubstitute the vectors in
d_result = d_result.subs(list(zip(d_funcs, vectors)))
# Third step: evaluate the derivatives of the vectors
derivs = []
for v in vectors:
d = Add(*[(self._christoffel[k, wrt_vector._index, v._index]
*v._coord_sys.base_vector(k))
for k in range(v._coord_sys.dim)])
derivs.append(d)
to_subs = [wrt_vector(d) for d in d_funcs]
# XXX: This substitution can fail when there are Dummy symbols and the
# cache is disabled: https://github.com/sympy/sympy/issues/17794
result = d_result.subs(list(zip(to_subs, derivs)))
# Remove the dummies
result = result.subs(list(zip(d_funcs, vectors)))
return result.doit()
class CovarDerivativeOp(Expr):
"""Covariant derivative operator.
Examples
========
>>> from sympy.diffgeom.rn import R2_r
>>> from sympy.diffgeom import CovarDerivativeOp
>>> from sympy.diffgeom import metric_to_Christoffel_2nd, TensorProduct
>>> TP = TensorProduct
>>> fx, fy = R2_r.base_scalars()
>>> e_x, e_y = R2_r.base_vectors()
>>> dx, dy = R2_r.base_oneforms()
>>> ch = metric_to_Christoffel_2nd(TP(dx, dx) + TP(dy, dy))
>>> ch
[[[0, 0], [0, 0]], [[0, 0], [0, 0]]]
>>> cvd = CovarDerivativeOp(fx*e_x, ch)
>>> cvd(fx)
x
>>> cvd(fx*e_x)
x*e_x
"""
def __new__(cls, wrt, christoffel):
if len({v._coord_sys for v in wrt.atoms(BaseVectorField)}) > 1:
raise NotImplementedError()
if contravariant_order(wrt) != 1 or covariant_order(wrt):
raise ValueError('Covariant derivatives are defined only with '
'respect to vector fields. The supplied argument '
'was not a vector field.')
obj = super().__new__(cls, wrt, christoffel)
# deprecated assigments
obj._wrt = wrt
obj._christoffel = christoffel
return obj
@property
def wrt(self):
return self.args[0]
@property
def christoffel(self):
return self.args[1]
def __call__(self, field):
vectors = list(self._wrt.atoms(BaseVectorField))
base_ops = [BaseCovarDerivativeOp(v._coord_sys, v._index, self._christoffel)
for v in vectors]
return self._wrt.subs(list(zip(vectors, base_ops))).rcall(field)
###############################################################################
# Integral curves on vector fields
###############################################################################
def intcurve_series(vector_field, param, start_point, n=6, coord_sys=None, coeffs=False):
r"""Return the series expansion for an integral curve of the field.
Explanation
===========
Integral curve is a function `\gamma` taking a parameter in `R` to a point
in the manifold. It verifies the equation:
`V(f)\big(\gamma(t)\big) = \frac{d}{dt}f\big(\gamma(t)\big)`
where the given ``vector_field`` is denoted as `V`. This holds for any
value `t` for the parameter and any scalar field `f`.
This equation can also be decomposed of a basis of coordinate functions
`V(f_i)\big(\gamma(t)\big) = \frac{d}{dt}f_i\big(\gamma(t)\big) \quad \forall i`
This function returns a series expansion of `\gamma(t)` in terms of the
coordinate system ``coord_sys``. The equations and expansions are necessarily
done in coordinate-system-dependent way as there is no other way to
represent movement between points on the manifold (i.e. there is no such
thing as a difference of points for a general manifold).
Parameters
==========
vector_field
the vector field for which an integral curve will be given
param
the argument of the function `\gamma` from R to the curve
start_point
the point which corresponds to `\gamma(0)`
n
the order to which to expand
coord_sys
the coordinate system in which to expand
coeffs (default False) - if True return a list of elements of the expansion
Examples
========
Use the predefined R2 manifold:
>>> from sympy.abc import t, x, y
>>> from sympy.diffgeom.rn import R2_p, R2_r
>>> from sympy.diffgeom import intcurve_series
Specify a starting point and a vector field:
>>> start_point = R2_r.point([x, y])
>>> vector_field = R2_r.e_x
Calculate the series:
>>> intcurve_series(vector_field, t, start_point, n=3)
Matrix([
[t + x],
[ y]])
Or get the elements of the expansion in a list:
>>> series = intcurve_series(vector_field, t, start_point, n=3, coeffs=True)
>>> series[0]
Matrix([
[x],
[y]])
>>> series[1]
Matrix([
[t],
[0]])
>>> series[2]
Matrix([
[0],
[0]])
The series in the polar coordinate system:
>>> series = intcurve_series(vector_field, t, start_point,
... n=3, coord_sys=R2_p, coeffs=True)
>>> series[0]
Matrix([
[sqrt(x**2 + y**2)],
[ atan2(y, x)]])
>>> series[1]
Matrix([
[t*x/sqrt(x**2 + y**2)],
[ -t*y/(x**2 + y**2)]])
>>> series[2]
Matrix([
[t**2*(-x**2/(x**2 + y**2)**(3/2) + 1/sqrt(x**2 + y**2))/2],
[ t**2*x*y/(x**2 + y**2)**2]])
See Also
========
intcurve_diffequ
"""
if contravariant_order(vector_field) != 1 or covariant_order(vector_field):
raise ValueError('The supplied field was not a vector field.')
def iter_vfield(scalar_field, i):
"""Return ``vector_field`` called `i` times on ``scalar_field``."""
return reduce(lambda s, v: v.rcall(s), [vector_field, ]*i, scalar_field)
def taylor_terms_per_coord(coord_function):
"""Return the series for one of the coordinates."""
return [param**i*iter_vfield(coord_function, i).rcall(start_point)/factorial(i)
for i in range(n)]
coord_sys = coord_sys if coord_sys else start_point._coord_sys
coord_functions = coord_sys.coord_functions()
taylor_terms = [taylor_terms_per_coord(f) for f in coord_functions]
if coeffs:
return [Matrix(t) for t in zip(*taylor_terms)]
else:
return Matrix([sum(c) for c in taylor_terms])
def intcurve_diffequ(vector_field, param, start_point, coord_sys=None):
r"""Return the differential equation for an integral curve of the field.
Explanation
===========
Integral curve is a function `\gamma` taking a parameter in `R` to a point
in the manifold. It verifies the equation:
`V(f)\big(\gamma(t)\big) = \frac{d}{dt}f\big(\gamma(t)\big)`
where the given ``vector_field`` is denoted as `V`. This holds for any
value `t` for the parameter and any scalar field `f`.
This function returns the differential equation of `\gamma(t)` in terms of the
coordinate system ``coord_sys``. The equations and expansions are necessarily
done in coordinate-system-dependent way as there is no other way to
represent movement between points on the manifold (i.e. there is no such
thing as a difference of points for a general manifold).
Parameters
==========
vector_field
the vector field for which an integral curve will be given
param
the argument of the function `\gamma` from R to the curve
start_point
the point which corresponds to `\gamma(0)`
coord_sys
the coordinate system in which to give the equations
Returns
=======
a tuple of (equations, initial conditions)
Examples
========
Use the predefined R2 manifold:
>>> from sympy.abc import t
>>> from sympy.diffgeom.rn import R2, R2_p, R2_r
>>> from sympy.diffgeom import intcurve_diffequ
Specify a starting point and a vector field:
>>> start_point = R2_r.point([0, 1])
>>> vector_field = -R2.y*R2.e_x + R2.x*R2.e_y
Get the equation:
>>> equations, init_cond = intcurve_diffequ(vector_field, t, start_point)
>>> equations
[f_1(t) + Derivative(f_0(t), t), -f_0(t) + Derivative(f_1(t), t)]
>>> init_cond
[f_0(0), f_1(0) - 1]
The series in the polar coordinate system:
>>> equations, init_cond = intcurve_diffequ(vector_field, t, start_point, R2_p)
>>> equations
[Derivative(f_0(t), t), Derivative(f_1(t), t) - 1]
>>> init_cond
[f_0(0) - 1, f_1(0) - pi/2]
See Also
========
intcurve_series
"""
if contravariant_order(vector_field) != 1 or covariant_order(vector_field):
raise ValueError('The supplied field was not a vector field.')
coord_sys = coord_sys if coord_sys else start_point._coord_sys
gammas = [Function('f_%d' % i)(param) for i in range(
start_point._coord_sys.dim)]
arbitrary_p = Point(coord_sys, gammas)
coord_functions = coord_sys.coord_functions()
equations = [simplify(diff(cf.rcall(arbitrary_p), param) - vector_field.rcall(cf).rcall(arbitrary_p))
for cf in coord_functions]
init_cond = [simplify(cf.rcall(arbitrary_p).subs(param, 0) - cf.rcall(start_point))
for cf in coord_functions]
return equations, init_cond
###############################################################################
# Helpers
###############################################################################
def dummyfy(args, exprs):
# TODO Is this a good idea?
d_args = Matrix([s.as_dummy() for s in args])
reps = dict(zip(args, d_args))
d_exprs = Matrix([_sympify(expr).subs(reps) for expr in exprs])
return d_args, d_exprs
###############################################################################
# Helpers
###############################################################################
def contravariant_order(expr, _strict=False):
"""Return the contravariant order of an expression.
Examples
========
>>> from sympy.diffgeom import contravariant_order
>>> from sympy.diffgeom.rn import R2
>>> from sympy.abc import a
>>> contravariant_order(a)
0
>>> contravariant_order(a*R2.x + 2)
0
>>> contravariant_order(a*R2.x*R2.e_y + R2.e_x)
1
"""
# TODO move some of this to class methods.
# TODO rewrite using the .as_blah_blah methods
if isinstance(expr, Add):
orders = [contravariant_order(e) for e in expr.args]
if len(set(orders)) != 1:
raise ValueError('Misformed expression containing contravariant fields of varying order.')
return orders[0]
elif isinstance(expr, Mul):
orders = [contravariant_order(e) for e in expr.args]
not_zero = [o for o in orders if o != 0]
if len(not_zero) > 1:
raise ValueError('Misformed expression containing multiplication between vectors.')
return 0 if not not_zero else not_zero[0]
elif isinstance(expr, Pow):
if covariant_order(expr.base) or covariant_order(expr.exp):
raise ValueError(
'Misformed expression containing a power of a vector.')
return 0
elif isinstance(expr, BaseVectorField):
return 1
elif isinstance(expr, TensorProduct):
return sum(contravariant_order(a) for a in expr.args)
elif not _strict or expr.atoms(BaseScalarField):
return 0
else: # If it does not contain anything related to the diffgeom module and it is _strict
return -1
def covariant_order(expr, _strict=False):
"""Return the covariant order of an expression.
Examples
========
>>> from sympy.diffgeom import covariant_order
>>> from sympy.diffgeom.rn import R2
>>> from sympy.abc import a
>>> covariant_order(a)
0
>>> covariant_order(a*R2.x + 2)
0
>>> covariant_order(a*R2.x*R2.dy + R2.dx)
1
"""
# TODO move some of this to class methods.
# TODO rewrite using the .as_blah_blah methods
if isinstance(expr, Add):
orders = [covariant_order(e) for e in expr.args]
if len(set(orders)) != 1:
raise ValueError('Misformed expression containing form fields of varying order.')
return orders[0]
elif isinstance(expr, Mul):
orders = [covariant_order(e) for e in expr.args]
not_zero = [o for o in orders if o != 0]
if len(not_zero) > 1:
raise ValueError('Misformed expression containing multiplication between forms.')
return 0 if not not_zero else not_zero[0]
elif isinstance(expr, Pow):
if covariant_order(expr.base) or covariant_order(expr.exp):
raise ValueError(
'Misformed expression containing a power of a form.')
return 0
elif isinstance(expr, Differential):
return covariant_order(*expr.args) + 1
elif isinstance(expr, TensorProduct):
return sum(covariant_order(a) for a in expr.args)
elif not _strict or expr.atoms(BaseScalarField):
return 0
else: # If it does not contain anything related to the diffgeom module and it is _strict
return -1
###############################################################################
# Coordinate transformation functions
###############################################################################
def vectors_in_basis(expr, to_sys):
"""Transform all base vectors in base vectors of a specified coord basis.
While the new base vectors are in the new coordinate system basis, any
coefficients are kept in the old system.
Examples
========
>>> from sympy.diffgeom import vectors_in_basis
>>> from sympy.diffgeom.rn import R2_r, R2_p
>>> vectors_in_basis(R2_r.e_x, R2_p)
-y*e_theta/(x**2 + y**2) + x*e_rho/sqrt(x**2 + y**2)
>>> vectors_in_basis(R2_p.e_r, R2_r)
sin(theta)*e_y + cos(theta)*e_x
"""
vectors = list(expr.atoms(BaseVectorField))
new_vectors = []
for v in vectors:
cs = v._coord_sys
jac = cs.jacobian(to_sys, cs.coord_functions())
new = (jac.T*Matrix(to_sys.base_vectors()))[v._index]
new_vectors.append(new)
return expr.subs(list(zip(vectors, new_vectors)))
###############################################################################
# Coordinate-dependent functions
###############################################################################
def twoform_to_matrix(expr):
"""Return the matrix representing the twoform.
For the twoform `w` return the matrix `M` such that `M[i,j]=w(e_i, e_j)`,
where `e_i` is the i-th base vector field for the coordinate system in
which the expression of `w` is given.
Examples
========
>>> from sympy.diffgeom.rn import R2
>>> from sympy.diffgeom import twoform_to_matrix, TensorProduct
>>> TP = TensorProduct
>>> twoform_to_matrix(TP(R2.dx, R2.dx) + TP(R2.dy, R2.dy))
Matrix([
[1, 0],
[0, 1]])
>>> twoform_to_matrix(R2.x*TP(R2.dx, R2.dx) + TP(R2.dy, R2.dy))
Matrix([
[x, 0],
[0, 1]])
>>> twoform_to_matrix(TP(R2.dx, R2.dx) + TP(R2.dy, R2.dy) - TP(R2.dx, R2.dy)/2)
Matrix([
[ 1, 0],
[-1/2, 1]])
"""
if covariant_order(expr) != 2 or contravariant_order(expr):
raise ValueError('The input expression is not a two-form.')
coord_sys = _find_coords(expr)
if len(coord_sys) != 1:
raise ValueError('The input expression concerns more than one '
'coordinate systems, hence there is no unambiguous '
'way to choose a coordinate system for the matrix.')
coord_sys = coord_sys.pop()
vectors = coord_sys.base_vectors()
expr = expr.expand()
matrix_content = [[expr.rcall(v1, v2) for v1 in vectors]
for v2 in vectors]
return Matrix(matrix_content)
def metric_to_Christoffel_1st(expr):
"""Return the nested list of Christoffel symbols for the given metric.
This returns the Christoffel symbol of first kind that represents the
Levi-Civita connection for the given metric.
Examples
========
>>> from sympy.diffgeom.rn import R2
>>> from sympy.diffgeom import metric_to_Christoffel_1st, TensorProduct
>>> TP = TensorProduct
>>> metric_to_Christoffel_1st(TP(R2.dx, R2.dx) + TP(R2.dy, R2.dy))
[[[0, 0], [0, 0]], [[0, 0], [0, 0]]]
>>> metric_to_Christoffel_1st(R2.x*TP(R2.dx, R2.dx) + TP(R2.dy, R2.dy))
[[[1/2, 0], [0, 0]], [[0, 0], [0, 0]]]
"""
matrix = twoform_to_matrix(expr)
if not matrix.is_symmetric():
raise ValueError(
'The two-form representing the metric is not symmetric.')
coord_sys = _find_coords(expr).pop()
deriv_matrices = [matrix.applyfunc(lambda a: d(a))
for d in coord_sys.base_vectors()]
indices = list(range(coord_sys.dim))
christoffel = [[[(deriv_matrices[k][i, j] + deriv_matrices[j][i, k] - deriv_matrices[i][j, k])/2
for k in indices]
for j in indices]
for i in indices]
return ImmutableDenseNDimArray(christoffel)
def metric_to_Christoffel_2nd(expr):
"""Return the nested list of Christoffel symbols for the given metric.
This returns the Christoffel symbol of second kind that represents the
Levi-Civita connection for the given metric.
Examples
========
>>> from sympy.diffgeom.rn import R2
>>> from sympy.diffgeom import metric_to_Christoffel_2nd, TensorProduct
>>> TP = TensorProduct
>>> metric_to_Christoffel_2nd(TP(R2.dx, R2.dx) + TP(R2.dy, R2.dy))
[[[0, 0], [0, 0]], [[0, 0], [0, 0]]]
>>> metric_to_Christoffel_2nd(R2.x*TP(R2.dx, R2.dx) + TP(R2.dy, R2.dy))
[[[1/(2*x), 0], [0, 0]], [[0, 0], [0, 0]]]
"""
ch_1st = metric_to_Christoffel_1st(expr)
coord_sys = _find_coords(expr).pop()
indices = list(range(coord_sys.dim))
# XXX workaround, inverting a matrix does not work if it contains non
# symbols
#matrix = twoform_to_matrix(expr).inv()
matrix = twoform_to_matrix(expr)
s_fields = set()
for e in matrix:
s_fields.update(e.atoms(BaseScalarField))
s_fields = list(s_fields)
dums = coord_sys.symbols
matrix = matrix.subs(list(zip(s_fields, dums))).inv().subs(list(zip(dums, s_fields)))
# XXX end of workaround
christoffel = [[[Add(*[matrix[i, l]*ch_1st[l, j, k] for l in indices])
for k in indices]
for j in indices]
for i in indices]
return ImmutableDenseNDimArray(christoffel)
def metric_to_Riemann_components(expr):
"""Return the components of the Riemann tensor expressed in a given basis.
Given a metric it calculates the components of the Riemann tensor in the
canonical basis of the coordinate system in which the metric expression is
given.
Examples
========
>>> from sympy import exp
>>> from sympy.diffgeom.rn import R2
>>> from sympy.diffgeom import metric_to_Riemann_components, TensorProduct
>>> TP = TensorProduct
>>> metric_to_Riemann_components(TP(R2.dx, R2.dx) + TP(R2.dy, R2.dy))
[[[[0, 0], [0, 0]], [[0, 0], [0, 0]]], [[[0, 0], [0, 0]], [[0, 0], [0, 0]]]]
>>> non_trivial_metric = exp(2*R2.r)*TP(R2.dr, R2.dr) + \
R2.r**2*TP(R2.dtheta, R2.dtheta)
>>> non_trivial_metric
exp(2*rho)*TensorProduct(drho, drho) + rho**2*TensorProduct(dtheta, dtheta)
>>> riemann = metric_to_Riemann_components(non_trivial_metric)
>>> riemann[0, :, :, :]
[[[0, 0], [0, 0]], [[0, exp(-2*rho)*rho], [-exp(-2*rho)*rho, 0]]]
>>> riemann[1, :, :, :]
[[[0, -1/rho], [1/rho, 0]], [[0, 0], [0, 0]]]
"""
ch_2nd = metric_to_Christoffel_2nd(expr)
coord_sys = _find_coords(expr).pop()
indices = list(range(coord_sys.dim))
deriv_ch = [[[[d(ch_2nd[i, j, k])
for d in coord_sys.base_vectors()]
for k in indices]
for j in indices]
for i in indices]
riemann_a = [[[[deriv_ch[rho][sig][nu][mu] - deriv_ch[rho][sig][mu][nu]
for nu in indices]
for mu in indices]
for sig in indices]
for rho in indices]
riemann_b = [[[[Add(*[ch_2nd[rho, l, mu]*ch_2nd[l, sig, nu] - ch_2nd[rho, l, nu]*ch_2nd[l, sig, mu] for l in indices])
for nu in indices]
for mu in indices]
for sig in indices]
for rho in indices]
riemann = [[[[riemann_a[rho][sig][mu][nu] + riemann_b[rho][sig][mu][nu]
for nu in indices]
for mu in indices]
for sig in indices]
for rho in indices]
return ImmutableDenseNDimArray(riemann)
def metric_to_Ricci_components(expr):
"""Return the components of the Ricci tensor expressed in a given basis.
Given a metric it calculates the components of the Ricci tensor in the
canonical basis of the coordinate system in which the metric expression is
given.
Examples
========
>>> from sympy import exp
>>> from sympy.diffgeom.rn import R2
>>> from sympy.diffgeom import metric_to_Ricci_components, TensorProduct
>>> TP = TensorProduct
>>> metric_to_Ricci_components(TP(R2.dx, R2.dx) + TP(R2.dy, R2.dy))
[[0, 0], [0, 0]]
>>> non_trivial_metric = exp(2*R2.r)*TP(R2.dr, R2.dr) + \
R2.r**2*TP(R2.dtheta, R2.dtheta)
>>> non_trivial_metric
exp(2*rho)*TensorProduct(drho, drho) + rho**2*TensorProduct(dtheta, dtheta)
>>> metric_to_Ricci_components(non_trivial_metric)
[[1/rho, 0], [0, exp(-2*rho)*rho]]
"""
riemann = metric_to_Riemann_components(expr)
coord_sys = _find_coords(expr).pop()
indices = list(range(coord_sys.dim))
ricci = [[Add(*[riemann[k, i, k, j] for k in indices])
for j in indices]
for i in indices]
return ImmutableDenseNDimArray(ricci)
###############################################################################
# Classes for deprecation
###############################################################################
class _deprecated_container:
# This class gives deprecation warning.
# When deprecated features are completely deleted, this should be removed as well.
# See https://github.com/sympy/sympy/pull/19368
def __init__(self, feature, useinstead, issue, version, data):
super().__init__(data)
self.feature = feature
self.useinstead = useinstead
self.issue = issue
self.version = version
def warn(self):
SymPyDeprecationWarning(
feature=self.feature,
useinstead=self.useinstead,
issue=self.issue,
deprecated_since_version=self.version).warn()
def __iter__(self):
self.warn()
return super().__iter__()
def __getitem__(self, key):
self.warn()
return super().__getitem__(key)
def __contains__(self, key):
self.warn()
return super().__contains__(key)
class _deprecated_list(_deprecated_container, list):
pass
class _deprecated_dict(_deprecated_container, dict):
pass
|
38324053e2c0e06be2bac288713a0380d98da20488721463f9dacc4d38a04a58 | """
Classes and functions useful for rewriting expressions for optimized code
generation. Some languages (or standards thereof), e.g. C99, offer specialized
math functions for better performance and/or precision.
Using the ``optimize`` function in this module, together with a collection of
rules (represented as instances of ``Optimization``), one can rewrite the
expressions for this purpose::
>>> from sympy import Symbol, exp, log
>>> from sympy.codegen.rewriting import optimize, optims_c99
>>> x = Symbol('x')
>>> optimize(3*exp(2*x) - 3, optims_c99)
3*expm1(2*x)
>>> optimize(exp(2*x) - 1 - exp(-33), optims_c99)
expm1(2*x) - exp(-33)
>>> optimize(log(3*x + 3), optims_c99)
log1p(x) + log(3)
>>> optimize(log(2*x + 3), optims_c99)
log(2*x + 3)
The ``optims_c99`` imported above is tuple containing the following instances
(which may be imported from ``sympy.codegen.rewriting``):
- ``expm1_opt``
- ``log1p_opt``
- ``exp2_opt``
- ``log2_opt``
- ``log2const_opt``
"""
from sympy import cos, exp, log, Max, Min, Wild, expand_log, sign, sin, sinc, S
from sympy.assumptions import Q, ask
from sympy.codegen.cfunctions import log1p, log2, exp2, expm1
from sympy.codegen.matrix_nodes import MatrixSolve
from sympy.core.expr import UnevaluatedExpr
from sympy.core.power import Pow
from sympy.codegen.numpy_nodes import logaddexp, logaddexp2
from sympy.codegen.scipy_nodes import cosm1
from sympy.core.mul import Mul
from sympy.matrices.expressions.matexpr import MatrixSymbol
from sympy.utilities.iterables import sift
class Optimization:
""" Abstract base class for rewriting optimization.
Subclasses should implement ``__call__`` taking an expression
as argument.
Parameters
==========
cost_function : callable returning number
priority : number
"""
def __init__(self, cost_function=None, priority=1):
self.cost_function = cost_function
self.priority=priority
def cheapest(self, *args):
return sorted(args, key=self.cost_function)[0]
class ReplaceOptim(Optimization):
""" Rewriting optimization calling replace on expressions.
Explanation
===========
The instance can be used as a function on expressions for which
it will apply the ``replace`` method (see
:meth:`sympy.core.basic.Basic.replace`).
Parameters
==========
query :
First argument passed to replace.
value :
Second argument passed to replace.
Examples
========
>>> from sympy import Symbol
>>> from sympy.codegen.rewriting import ReplaceOptim
>>> from sympy.codegen.cfunctions import exp2
>>> x = Symbol('x')
>>> exp2_opt = ReplaceOptim(lambda p: p.is_Pow and p.base == 2,
... lambda p: exp2(p.exp))
>>> exp2_opt(2**x)
exp2(x)
"""
def __init__(self, query, value, **kwargs):
super().__init__(**kwargs)
self.query = query
self.value = value
def __call__(self, expr):
return expr.replace(self.query, self.value)
def optimize(expr, optimizations):
""" Apply optimizations to an expression.
Parameters
==========
expr : expression
optimizations : iterable of ``Optimization`` instances
The optimizations will be sorted with respect to ``priority`` (highest first).
Examples
========
>>> from sympy import log, Symbol
>>> from sympy.codegen.rewriting import optims_c99, optimize
>>> x = Symbol('x')
>>> optimize(log(x+3)/log(2) + log(x**2 + 1), optims_c99)
log1p(x**2) + log2(x + 3)
"""
for optim in sorted(optimizations, key=lambda opt: opt.priority, reverse=True):
new_expr = optim(expr)
if optim.cost_function is None:
expr = new_expr
else:
expr = optim.cheapest(expr, new_expr)
return expr
exp2_opt = ReplaceOptim(
lambda p: p.is_Pow and p.base == 2,
lambda p: exp2(p.exp)
)
_d = Wild('d', properties=[lambda x: x.is_Dummy])
_u = Wild('u', properties=[lambda x: not x.is_number and not x.is_Add])
_v = Wild('v')
_w = Wild('w')
_n = Wild('n', properties=[lambda x: x.is_number])
sinc_opt1 = ReplaceOptim(
sin(_w)/_w, sinc(_w)
)
sinc_opt2 = ReplaceOptim(
sin(_n*_w)/_w, _n*sinc(_n*_w)
)
sinc_opts = (sinc_opt1, sinc_opt2)
log2_opt = ReplaceOptim(_v*log(_w)/log(2), _v*log2(_w), cost_function=lambda expr: expr.count(
lambda e: ( # division & eval of transcendentals are expensive floating point operations...
e.is_Pow and e.exp.is_negative # division
or (isinstance(e, (log, log2)) and not e.args[0].is_number)) # transcendental
)
)
log2const_opt = ReplaceOptim(log(2)*log2(_w), log(_w))
logsumexp_2terms_opt = ReplaceOptim(
lambda l: (isinstance(l, log)
and l.args[0].is_Add
and len(l.args[0].args) == 2
and all(isinstance(t, exp) for t in l.args[0].args)),
lambda l: (
Max(*[e.args[0] for e in l.args[0].args]) +
log1p(exp(Min(*[e.args[0] for e in l.args[0].args])))
)
)
class FuncMinusOneOptim(ReplaceOptim):
"""Specialization of ReplaceOptim for functions evaluating "f(x) - 1".
Explanation
===========
Numerical functions which go toward one as x go toward zero is often best
implemented by a dedicated function in order to avoid catastrophic
cancellation. One such example is ``expm1(x)`` in the C standard library
which evaluates ``exp(x) - 1``. Such functions preserves many more
significant digits when its argument is much smaller than one, compared
to subtracting one afterwards.
Parameters
==========
func :
The function which is subtracted by one.
func_m_1 :
The specialized function evaluating ``func(x) - 1``.
opportunistic : bool
When ``True``, apply the transformation as long as the magnitude of the
remaining number terms decreases. When ``False``, only apply the
transformation if it completely eliminates the number term.
Examples
========
>>> from sympy import symbols, exp
>>> from sympy.codegen.rewriting import FuncMinusOneOptim
>>> from sympy.codegen.cfunctions import expm1
>>> x, y = symbols('x y')
>>> expm1_opt = FuncMinusOneOptim(exp, expm1)
>>> expm1_opt(exp(x) + 2*exp(5*y) - 3)
expm1(x) + 2*expm1(5*y)
"""
def __init__(self, func, func_m_1, opportunistic=True):
weight = 10 # <-- this is an arbitrary number (heuristic)
super().__init__(lambda e: e.is_Add, self.replace_in_Add,
cost_function=lambda expr: expr.count_ops() - weight*expr.count(func_m_1))
self.func = func
self.func_m_1 = func_m_1
self.opportunistic = opportunistic
def _group_Add_terms(self, add):
numbers, non_num = sift(add.args, lambda arg: arg.is_number, binary=True)
numsum = sum(numbers)
terms_with_func, other = sift(non_num, lambda arg: arg.has(self.func), binary=True)
return numsum, terms_with_func, other
def replace_in_Add(self, e):
""" passed as second argument to Basic.replace(...) """
numsum, terms_with_func, other_non_num_terms = self._group_Add_terms(e)
if numsum == 0:
return e
substituted, untouched = [], []
for with_func in terms_with_func:
if with_func.is_Mul:
func, coeff = sift(with_func.args, lambda arg: arg.func == self.func, binary=True)
if len(func) == 1 and len(coeff) == 1:
func, coeff = func[0], coeff[0]
else:
coeff = None
elif with_func.func == self.func:
func, coeff = with_func, S.One
else:
coeff = None
if coeff is not None and coeff.is_number and sign(coeff) == -sign(numsum):
if self.opportunistic:
do_substitute = abs(coeff+numsum) < abs(numsum)
else:
do_substitute = coeff+numsum == 0
if do_substitute: # advantageous substitution
numsum += coeff
substituted.append(coeff*self.func_m_1(*func.args))
continue
untouched.append(with_func)
return e.func(numsum, *substituted, *untouched, *other_non_num_terms)
def __call__(self, expr):
alt1 = super().__call__(expr)
alt2 = super().__call__(expr.factor())
return self.cheapest(alt1, alt2)
expm1_opt = FuncMinusOneOptim(exp, expm1)
cosm1_opt = FuncMinusOneOptim(cos, cosm1)
log1p_opt = ReplaceOptim(
lambda e: isinstance(e, log),
lambda l: expand_log(l.replace(
log, lambda arg: log(arg.factor())
)).replace(log(_u+1), log1p(_u))
)
def create_expand_pow_optimization(limit, *, base_req=lambda b: b.is_symbol):
""" Creates an instance of :class:`ReplaceOptim` for expanding ``Pow``.
Explanation
===========
The requirements for expansions are that the base needs to be a symbol
and the exponent needs to be an Integer (and be less than or equal to
``limit``).
Parameters
==========
limit : int
The highest power which is expanded into multiplication.
base_req : function returning bool
Requirement on base for expansion to happen, default is to return
the ``is_symbol`` attribute of the base.
Examples
========
>>> from sympy import Symbol, sin
>>> from sympy.codegen.rewriting import create_expand_pow_optimization
>>> x = Symbol('x')
>>> expand_opt = create_expand_pow_optimization(3)
>>> expand_opt(x**5 + x**3)
x**5 + x*x*x
>>> expand_opt(x**5 + x**3 + sin(x)**3)
x**5 + sin(x)**3 + x*x*x
>>> opt2 = create_expand_pow_optimization(3 , base_req=lambda b: not b.is_Function)
>>> opt2((x+1)**2 + sin(x)**2)
sin(x)**2 + (x + 1)*(x + 1)
"""
return ReplaceOptim(
lambda e: e.is_Pow and base_req(e.base) and e.exp.is_Integer and abs(e.exp) <= limit,
lambda p: (
UnevaluatedExpr(Mul(*([p.base]*+p.exp), evaluate=False)) if p.exp > 0 else
1/UnevaluatedExpr(Mul(*([p.base]*-p.exp), evaluate=False))
))
# Optimization procedures for turning A**(-1) * x into MatrixSolve(A, x)
def _matinv_predicate(expr):
# TODO: We should be able to support more than 2 elements
if expr.is_MatMul and len(expr.args) == 2:
left, right = expr.args
if left.is_Inverse and right.shape[1] == 1:
inv_arg = left.arg
if isinstance(inv_arg, MatrixSymbol):
return bool(ask(Q.fullrank(left.arg)))
return False
def _matinv_transform(expr):
left, right = expr.args
inv_arg = left.arg
return MatrixSolve(inv_arg, right)
matinv_opt = ReplaceOptim(_matinv_predicate, _matinv_transform)
logaddexp_opt = ReplaceOptim(log(exp(_v)+exp(_w)), logaddexp(_v, _w))
logaddexp2_opt = ReplaceOptim(log(Pow(2, _v)+Pow(2, _w)), logaddexp2(_v, _w)*log(2))
# Collections of optimizations:
optims_c99 = (expm1_opt, log1p_opt, exp2_opt, log2_opt, log2const_opt)
optims_numpy = optims_c99 + (logaddexp_opt, logaddexp2_opt,) + sinc_opts
optims_scipy = (cosm1_opt,)
|
aaeff5e004e92624f3d1a70b5f643abdc5f0a715790c03cb2f9df1e8d7b4f677 | """
Types used to represent a full function/module as an Abstract Syntax Tree.
Most types are small, and are merely used as tokens in the AST. A tree diagram
has been included below to illustrate the relationships between the AST types.
AST Type Tree
-------------
::
*Basic*
|--->AssignmentBase
| |--->Assignment
| |--->AugmentedAssignment
| |--->AddAugmentedAssignment
| |--->SubAugmentedAssignment
| |--->MulAugmentedAssignment
| |--->DivAugmentedAssignment
| |--->ModAugmentedAssignment
|
|--->CodeBlock
|
|
|--->Token
| |--->Attribute
| |--->For
| |--->String
| | |--->QuotedString
| | |--->Comment
| |--->Type
| | |--->IntBaseType
| | | |--->_SizedIntType
| | | |--->SignedIntType
| | | |--->UnsignedIntType
| | |--->FloatBaseType
| | |--->FloatType
| | |--->ComplexBaseType
| | |--->ComplexType
| |--->Node
| | |--->Variable
| | | |---> Pointer
| | |--->FunctionPrototype
| | |--->FunctionDefinition
| |--->Element
| |--->Declaration
| |--->While
| |--->Scope
| |--->Stream
| |--->Print
| |--->FunctionCall
| |--->BreakToken
| |--->ContinueToken
| |--->NoneToken
|
|--->Statement
|--->Return
Predefined types
----------------
A number of ``Type`` instances are provided in the ``sympy.codegen.ast`` module
for convenience. Perhaps the two most common ones for code-generation (of numeric
codes) are ``float32`` and ``float64`` (known as single and double precision respectively).
There are also precision generic versions of Types (for which the codeprinters selects the
underlying data type at time of printing): ``real``, ``integer``, ``complex_``, ``bool_``.
The other ``Type`` instances defined are:
- ``intc``: Integer type used by C's "int".
- ``intp``: Integer type used by C's "unsigned".
- ``int8``, ``int16``, ``int32``, ``int64``: n-bit integers.
- ``uint8``, ``uint16``, ``uint32``, ``uint64``: n-bit unsigned integers.
- ``float80``: known as "extended precision" on modern x86/amd64 hardware.
- ``complex64``: Complex number represented by two ``float32`` numbers
- ``complex128``: Complex number represented by two ``float64`` numbers
Using the nodes
---------------
It is possible to construct simple algorithms using the AST nodes. Let's construct a loop applying
Newton's method::
>>> from sympy import symbols, cos
>>> from sympy.codegen.ast import While, Assignment, aug_assign, Print
>>> t, dx, x = symbols('tol delta val')
>>> expr = cos(x) - x**3
>>> whl = While(abs(dx) > t, [
... Assignment(dx, -expr/expr.diff(x)),
... aug_assign(x, '+', dx),
... Print([x])
... ])
>>> from sympy.printing import pycode
>>> py_str = pycode(whl)
>>> print(py_str)
while (abs(delta) > tol):
delta = (val**3 - math.cos(val))/(-3*val**2 - math.sin(val))
val += delta
print(val)
>>> import math
>>> tol, val, delta = 1e-5, 0.5, float('inf')
>>> exec(py_str)
1.1121416371
0.909672693737
0.867263818209
0.865477135298
0.865474033111
>>> print('%3.1g' % (math.cos(val) - val**3))
-3e-11
If we want to generate Fortran code for the same while loop we simple call ``fcode``::
>>> from sympy.printing import fcode
>>> print(fcode(whl, standard=2003, source_format='free'))
do while (abs(delta) > tol)
delta = (val**3 - cos(val))/(-3*val**2 - sin(val))
val = val + delta
print *, val
end do
There is a function constructing a loop (or a complete function) like this in
:mod:`sympy.codegen.algorithms`.
"""
from typing import Any, Dict, List
from collections import defaultdict
from sympy import Lt, Le, Ge, Gt
from sympy.core import Symbol, Tuple, Dummy
from sympy.core.basic import Basic
from sympy.core.expr import Expr
from sympy.core.numbers import Float, Integer, oo
from sympy.core.sympify import _sympify, sympify, SympifyError
from sympy.utilities.iterables import iterable
def _mk_Tuple(args):
"""
Create a Sympy Tuple object from an iterable, converting Python strings to
AST strings.
Parameters
==========
args: iterable
Arguments to :class:`sympy.Tuple`.
Returns
=======
sympy.Tuple
"""
args = [String(arg) if isinstance(arg, str) else arg for arg in args]
return Tuple(*args)
class Token(Basic):
""" Base class for the AST types.
Explanation
===========
Defining fields are set in ``__slots__``. Attributes (defined in __slots__)
are only allowed to contain instances of Basic (unless atomic, see
``String``). The arguments to ``__new__()`` correspond to the attributes in
the order defined in ``__slots__`. The ``defaults`` class attribute is a
dictionary mapping attribute names to their default values.
Subclasses should not need to override the ``__new__()`` method. They may
define a class or static method named ``_construct_<attr>`` for each
attribute to process the value passed to ``__new__()``. Attributes listed
in the class attribute ``not_in_args`` are not passed to :class:`~.Basic`.
"""
__slots__ = ()
defaults = {} # type: Dict[str, Any]
not_in_args = [] # type: List[str]
indented_args = ['body']
@property
def is_Atom(self):
return len(self.__slots__) == 0
@classmethod
def _get_constructor(cls, attr):
""" Get the constructor function for an attribute by name. """
return getattr(cls, '_construct_%s' % attr, lambda x: x)
@classmethod
def _construct(cls, attr, arg):
""" Construct an attribute value from argument passed to ``__new__()``. """
# arg may be ``NoneToken()``, so comparation is done using == instead of ``is`` operator
if arg == None:
return cls.defaults.get(attr, none)
else:
if isinstance(arg, Dummy): # sympy's replace uses Dummy instances
return arg
else:
return cls._get_constructor(attr)(arg)
def __new__(cls, *args, **kwargs):
# Pass through existing instances when given as sole argument
if len(args) == 1 and not kwargs and isinstance(args[0], cls):
return args[0]
if len(args) > len(cls.__slots__):
raise ValueError("Too many arguments (%d), expected at most %d" % (len(args), len(cls.__slots__)))
attrvals = []
# Process positional arguments
for attrname, argval in zip(cls.__slots__, args):
if attrname in kwargs:
raise TypeError('Got multiple values for attribute %r' % attrname)
attrvals.append(cls._construct(attrname, argval))
# Process keyword arguments
for attrname in cls.__slots__[len(args):]:
if attrname in kwargs:
argval = kwargs.pop(attrname)
elif attrname in cls.defaults:
argval = cls.defaults[attrname]
else:
raise TypeError('No value for %r given and attribute has no default' % attrname)
attrvals.append(cls._construct(attrname, argval))
if kwargs:
raise ValueError("Unknown keyword arguments: %s" % ' '.join(kwargs))
# Parent constructor
basic_args = [
val for attr, val in zip(cls.__slots__, attrvals)
if attr not in cls.not_in_args
]
obj = Basic.__new__(cls, *basic_args)
# Set attributes
for attr, arg in zip(cls.__slots__, attrvals):
setattr(obj, attr, arg)
return obj
def __eq__(self, other):
if not isinstance(other, self.__class__):
return False
for attr in self.__slots__:
if getattr(self, attr) != getattr(other, attr):
return False
return True
def _hashable_content(self):
return tuple([getattr(self, attr) for attr in self.__slots__])
def __hash__(self):
return super().__hash__()
def _joiner(self, k, indent_level):
return (',\n' + ' '*indent_level) if k in self.indented_args else ', '
def _indented(self, printer, k, v, *args, **kwargs):
il = printer._context['indent_level']
def _print(arg):
if isinstance(arg, Token):
return printer._print(arg, *args, joiner=self._joiner(k, il), **kwargs)
else:
return printer._print(arg, *args, **kwargs)
if isinstance(v, Tuple):
joined = self._joiner(k, il).join([_print(arg) for arg in v.args])
if k in self.indented_args:
return '(\n' + ' '*il + joined + ',\n' + ' '*(il - 4) + ')'
else:
return ('({0},)' if len(v.args) == 1 else '({0})').format(joined)
else:
return _print(v)
def _sympyrepr(self, printer, *args, joiner=', ', **kwargs):
from sympy.printing.printer import printer_context
exclude = kwargs.get('exclude', ())
values = [getattr(self, k) for k in self.__slots__]
indent_level = printer._context.get('indent_level', 0)
arg_reprs = []
for i, (attr, value) in enumerate(zip(self.__slots__, values)):
if attr in exclude:
continue
# Skip attributes which have the default value
if attr in self.defaults and value == self.defaults[attr]:
continue
ilvl = indent_level + 4 if attr in self.indented_args else 0
with printer_context(printer, indent_level=ilvl):
indented = self._indented(printer, attr, value, *args, **kwargs)
arg_reprs.append(('{1}' if i == 0 else '{0}={1}').format(attr, indented.lstrip()))
return "{}({})".format(self.__class__.__name__, joiner.join(arg_reprs))
_sympystr = _sympyrepr
def __repr__(self): # sympy.core.Basic.__repr__ uses sstr
from sympy.printing import srepr
return srepr(self)
def kwargs(self, exclude=(), apply=None):
""" Get instance's attributes as dict of keyword arguments.
Parameters
==========
exclude : collection of str
Collection of keywords to exclude.
apply : callable, optional
Function to apply to all values.
"""
kwargs = {k: getattr(self, k) for k in self.__slots__ if k not in exclude}
if apply is not None:
return {k: apply(v) for k, v in kwargs.items()}
else:
return kwargs
class BreakToken(Token):
""" Represents 'break' in C/Python ('exit' in Fortran).
Use the premade instance ``break_`` or instantiate manually.
Examples
========
>>> from sympy.printing import ccode, fcode
>>> from sympy.codegen.ast import break_
>>> ccode(break_)
'break'
>>> fcode(break_, source_format='free')
'exit'
"""
break_ = BreakToken()
class ContinueToken(Token):
""" Represents 'continue' in C/Python ('cycle' in Fortran)
Use the premade instance ``continue_`` or instantiate manually.
Examples
========
>>> from sympy.printing import ccode, fcode
>>> from sympy.codegen.ast import continue_
>>> ccode(continue_)
'continue'
>>> fcode(continue_, source_format='free')
'cycle'
"""
continue_ = ContinueToken()
class NoneToken(Token):
""" The AST equivalence of Python's NoneType
The corresponding instance of Python's ``None`` is ``none``.
Examples
========
>>> from sympy.codegen.ast import none, Variable
>>> from sympy.printing.pycode import pycode
>>> print(pycode(Variable('x').as_Declaration(value=none)))
x = None
"""
def __eq__(self, other):
return other is None or isinstance(other, NoneToken)
def _hashable_content(self):
return ()
def __hash__(self):
return super().__hash__()
none = NoneToken()
class AssignmentBase(Basic):
""" Abstract base class for Assignment and AugmentedAssignment.
Attributes:
===========
op : str
Symbol for assignment operator, e.g. "=", "+=", etc.
"""
def __new__(cls, lhs, rhs):
lhs = _sympify(lhs)
rhs = _sympify(rhs)
cls._check_args(lhs, rhs)
return super().__new__(cls, lhs, rhs)
@property
def lhs(self):
return self.args[0]
@property
def rhs(self):
return self.args[1]
@classmethod
def _check_args(cls, lhs, rhs):
""" Check arguments to __new__ and raise exception if any problems found.
Derived classes may wish to override this.
"""
from sympy.matrices.expressions.matexpr import (
MatrixElement, MatrixSymbol)
from sympy.tensor.indexed import Indexed
# Tuple of things that can be on the lhs of an assignment
assignable = (Symbol, MatrixSymbol, MatrixElement, Indexed, Element, Variable)
if not isinstance(lhs, assignable):
raise TypeError("Cannot assign to lhs of type %s." % type(lhs))
# Indexed types implement shape, but don't define it until later. This
# causes issues in assignment validation. For now, matrices are defined
# as anything with a shape that is not an Indexed
lhs_is_mat = hasattr(lhs, 'shape') and not isinstance(lhs, Indexed)
rhs_is_mat = hasattr(rhs, 'shape') and not isinstance(rhs, Indexed)
# If lhs and rhs have same structure, then this assignment is ok
if lhs_is_mat:
if not rhs_is_mat:
raise ValueError("Cannot assign a scalar to a matrix.")
elif lhs.shape != rhs.shape:
raise ValueError("Dimensions of lhs and rhs don't align.")
elif rhs_is_mat and not lhs_is_mat:
raise ValueError("Cannot assign a matrix to a scalar.")
class Assignment(AssignmentBase):
"""
Represents variable assignment for code generation.
Parameters
==========
lhs : Expr
Sympy object representing the lhs of the expression. These should be
singular objects, such as one would use in writing code. Notable types
include Symbol, MatrixSymbol, MatrixElement, and Indexed. Types that
subclass these types are also supported.
rhs : Expr
Sympy object representing the rhs of the expression. This can be any
type, provided its shape corresponds to that of the lhs. For example,
a Matrix type can be assigned to MatrixSymbol, but not to Symbol, as
the dimensions will not align.
Examples
========
>>> from sympy import symbols, MatrixSymbol, Matrix
>>> from sympy.codegen.ast import Assignment
>>> x, y, z = symbols('x, y, z')
>>> Assignment(x, y)
Assignment(x, y)
>>> Assignment(x, 0)
Assignment(x, 0)
>>> A = MatrixSymbol('A', 1, 3)
>>> mat = Matrix([x, y, z]).T
>>> Assignment(A, mat)
Assignment(A, Matrix([[x, y, z]]))
>>> Assignment(A[0, 1], x)
Assignment(A[0, 1], x)
"""
op = ':='
class AugmentedAssignment(AssignmentBase):
"""
Base class for augmented assignments.
Attributes:
===========
binop : str
Symbol for binary operation being applied in the assignment, such as "+",
"*", etc.
"""
binop = None # type: str
@property
def op(self):
return self.binop + '='
class AddAugmentedAssignment(AugmentedAssignment):
binop = '+'
class SubAugmentedAssignment(AugmentedAssignment):
binop = '-'
class MulAugmentedAssignment(AugmentedAssignment):
binop = '*'
class DivAugmentedAssignment(AugmentedAssignment):
binop = '/'
class ModAugmentedAssignment(AugmentedAssignment):
binop = '%'
# Mapping from binary op strings to AugmentedAssignment subclasses
augassign_classes = {
cls.binop: cls for cls in [
AddAugmentedAssignment, SubAugmentedAssignment, MulAugmentedAssignment,
DivAugmentedAssignment, ModAugmentedAssignment
]
}
def aug_assign(lhs, op, rhs):
"""
Create 'lhs op= rhs'.
Explanation
===========
Represents augmented variable assignment for code generation. This is a
convenience function. You can also use the AugmentedAssignment classes
directly, like AddAugmentedAssignment(x, y).
Parameters
==========
lhs : Expr
Sympy object representing the lhs of the expression. These should be
singular objects, such as one would use in writing code. Notable types
include Symbol, MatrixSymbol, MatrixElement, and Indexed. Types that
subclass these types are also supported.
op : str
Operator (+, -, /, \\*, %).
rhs : Expr
Sympy object representing the rhs of the expression. This can be any
type, provided its shape corresponds to that of the lhs. For example,
a Matrix type can be assigned to MatrixSymbol, but not to Symbol, as
the dimensions will not align.
Examples
========
>>> from sympy import symbols
>>> from sympy.codegen.ast import aug_assign
>>> x, y = symbols('x, y')
>>> aug_assign(x, '+', y)
AddAugmentedAssignment(x, y)
"""
if op not in augassign_classes:
raise ValueError("Unrecognized operator %s" % op)
return augassign_classes[op](lhs, rhs)
class CodeBlock(Basic):
"""
Represents a block of code.
Explanation
===========
For now only assignments are supported. This restriction will be lifted in
the future.
Useful attributes on this object are:
``left_hand_sides``:
Tuple of left-hand sides of assignments, in order.
``left_hand_sides``:
Tuple of right-hand sides of assignments, in order.
``free_symbols``: Free symbols of the expressions in the right-hand sides
which do not appear in the left-hand side of an assignment.
Useful methods on this object are:
``topological_sort``:
Class method. Return a CodeBlock with assignments
sorted so that variables are assigned before they
are used.
``cse``:
Return a new CodeBlock with common subexpressions eliminated and
pulled out as assignments.
Examples
========
>>> from sympy import symbols, ccode
>>> from sympy.codegen.ast import CodeBlock, Assignment
>>> x, y = symbols('x y')
>>> c = CodeBlock(Assignment(x, 1), Assignment(y, x + 1))
>>> print(ccode(c))
x = 1;
y = x + 1;
"""
def __new__(cls, *args):
left_hand_sides = []
right_hand_sides = []
for i in args:
if isinstance(i, Assignment):
lhs, rhs = i.args
left_hand_sides.append(lhs)
right_hand_sides.append(rhs)
obj = Basic.__new__(cls, *args)
obj.left_hand_sides = Tuple(*left_hand_sides)
obj.right_hand_sides = Tuple(*right_hand_sides)
return obj
def __iter__(self):
return iter(self.args)
def _sympyrepr(self, printer, *args, **kwargs):
il = printer._context.get('indent_level', 0)
joiner = ',\n' + ' '*il
joined = joiner.join(map(printer._print, self.args))
return ('{}(\n'.format(' '*(il-4) + self.__class__.__name__,) +
' '*il + joined + '\n' + ' '*(il - 4) + ')')
_sympystr = _sympyrepr
@property
def free_symbols(self):
return super().free_symbols - set(self.left_hand_sides)
@classmethod
def topological_sort(cls, assignments):
"""
Return a CodeBlock with topologically sorted assignments so that
variables are assigned before they are used.
Examples
========
The existing order of assignments is preserved as much as possible.
This function assumes that variables are assigned to only once.
This is a class constructor so that the default constructor for
CodeBlock can error when variables are used before they are assigned.
Examples
========
>>> from sympy import symbols
>>> from sympy.codegen.ast import CodeBlock, Assignment
>>> x, y, z = symbols('x y z')
>>> assignments = [
... Assignment(x, y + z),
... Assignment(y, z + 1),
... Assignment(z, 2),
... ]
>>> CodeBlock.topological_sort(assignments)
CodeBlock(
Assignment(z, 2),
Assignment(y, z + 1),
Assignment(x, y + z)
)
"""
from sympy.utilities.iterables import topological_sort
if not all(isinstance(i, Assignment) for i in assignments):
# Will support more things later
raise NotImplementedError("CodeBlock.topological_sort only supports Assignments")
if any(isinstance(i, AugmentedAssignment) for i in assignments):
raise NotImplementedError("CodeBlock.topological_sort doesn't yet work with AugmentedAssignments")
# Create a graph where the nodes are assignments and there is a directed edge
# between nodes that use a variable and nodes that assign that
# variable, like
# [(x := 1, y := x + 1), (x := 1, z := y + z), (y := x + 1, z := y + z)]
# If we then topologically sort these nodes, they will be in
# assignment order, like
# x := 1
# y := x + 1
# z := y + z
# A = The nodes
#
# enumerate keeps nodes in the same order they are already in if
# possible. It will also allow us to handle duplicate assignments to
# the same variable when those are implemented.
A = list(enumerate(assignments))
# var_map = {variable: [nodes for which this variable is assigned to]}
# like {x: [(1, x := y + z), (4, x := 2 * w)], ...}
var_map = defaultdict(list)
for node in A:
i, a = node
var_map[a.lhs].append(node)
# E = Edges in the graph
E = []
for dst_node in A:
i, a = dst_node
for s in a.rhs.free_symbols:
for src_node in var_map[s]:
E.append((src_node, dst_node))
ordered_assignments = topological_sort([A, E])
# De-enumerate the result
return cls(*[a for i, a in ordered_assignments])
def cse(self, symbols=None, optimizations=None, postprocess=None,
order='canonical'):
"""
Return a new code block with common subexpressions eliminated.
Explanation
===========
See the docstring of :func:`sympy.simplify.cse_main.cse` for more
information.
Examples
========
>>> from sympy import symbols, sin
>>> from sympy.codegen.ast import CodeBlock, Assignment
>>> x, y, z = symbols('x y z')
>>> c = CodeBlock(
... Assignment(x, 1),
... Assignment(y, sin(x) + 1),
... Assignment(z, sin(x) - 1),
... )
...
>>> c.cse()
CodeBlock(
Assignment(x, 1),
Assignment(x0, sin(x)),
Assignment(y, x0 + 1),
Assignment(z, x0 - 1)
)
"""
from sympy.simplify.cse_main import cse
from sympy.utilities.iterables import numbered_symbols, filter_symbols
# Check that the CodeBlock only contains assignments to unique variables
if not all(isinstance(i, Assignment) for i in self.args):
# Will support more things later
raise NotImplementedError("CodeBlock.cse only supports Assignments")
if any(isinstance(i, AugmentedAssignment) for i in self.args):
raise NotImplementedError("CodeBlock.cse doesn't yet work with AugmentedAssignments")
for i, lhs in enumerate(self.left_hand_sides):
if lhs in self.left_hand_sides[:i]:
raise NotImplementedError("Duplicate assignments to the same "
"variable are not yet supported (%s)" % lhs)
# Ensure new symbols for subexpressions do not conflict with existing
existing_symbols = self.atoms(Symbol)
if symbols is None:
symbols = numbered_symbols()
symbols = filter_symbols(symbols, existing_symbols)
replacements, reduced_exprs = cse(list(self.right_hand_sides),
symbols=symbols, optimizations=optimizations, postprocess=postprocess,
order=order)
new_block = [Assignment(var, expr) for var, expr in
zip(self.left_hand_sides, reduced_exprs)]
new_assignments = [Assignment(var, expr) for var, expr in replacements]
return self.topological_sort(new_assignments + new_block)
class For(Token):
"""Represents a 'for-loop' in the code.
Expressions are of the form:
"for target in iter:
body..."
Parameters
==========
target : symbol
iter : iterable
body : CodeBlock or iterable
! When passed an iterable it is used to instantiate a CodeBlock.
Examples
========
>>> from sympy import symbols, Range
>>> from sympy.codegen.ast import aug_assign, For
>>> x, i, j, k = symbols('x i j k')
>>> for_i = For(i, Range(10), [aug_assign(x, '+', i*j*k)])
>>> for_i # doctest: -NORMALIZE_WHITESPACE
For(i, iterable=Range(0, 10, 1), body=CodeBlock(
AddAugmentedAssignment(x, i*j*k)
))
>>> for_ji = For(j, Range(7), [for_i])
>>> for_ji # doctest: -NORMALIZE_WHITESPACE
For(j, iterable=Range(0, 7, 1), body=CodeBlock(
For(i, iterable=Range(0, 10, 1), body=CodeBlock(
AddAugmentedAssignment(x, i*j*k)
))
))
>>> for_kji =For(k, Range(5), [for_ji])
>>> for_kji # doctest: -NORMALIZE_WHITESPACE
For(k, iterable=Range(0, 5, 1), body=CodeBlock(
For(j, iterable=Range(0, 7, 1), body=CodeBlock(
For(i, iterable=Range(0, 10, 1), body=CodeBlock(
AddAugmentedAssignment(x, i*j*k)
))
))
))
"""
__slots__ = ('target', 'iterable', 'body')
_construct_target = staticmethod(_sympify)
@classmethod
def _construct_body(cls, itr):
if isinstance(itr, CodeBlock):
return itr
else:
return CodeBlock(*itr)
@classmethod
def _construct_iterable(cls, itr):
if not iterable(itr):
raise TypeError("iterable must be an iterable")
if isinstance(itr, list): # _sympify errors on lists because they are mutable
itr = tuple(itr)
return _sympify(itr)
class String(Token):
""" SymPy object representing a string.
Atomic object which is not an expression (as opposed to Symbol).
Parameters
==========
text : str
Examples
========
>>> from sympy.codegen.ast import String
>>> f = String('foo')
>>> f
foo
>>> str(f)
'foo'
>>> f.text
'foo'
>>> print(repr(f))
String('foo')
"""
__slots__ = ('text',)
not_in_args = ['text']
is_Atom = True
@classmethod
def _construct_text(cls, text):
if not isinstance(text, str):
raise TypeError("Argument text is not a string type.")
return text
def _sympystr(self, printer, *args, **kwargs):
return self.text
class QuotedString(String):
""" Represents a string which should be printed with quotes. """
class Comment(String):
""" Represents a comment. """
class Node(Token):
""" Subclass of Token, carrying the attribute 'attrs' (Tuple)
Examples
========
>>> from sympy.codegen.ast import Node, value_const, pointer_const
>>> n1 = Node([value_const])
>>> n1.attr_params('value_const') # get the parameters of attribute (by name)
()
>>> from sympy.codegen.fnodes import dimension
>>> n2 = Node([value_const, dimension(5, 3)])
>>> n2.attr_params(value_const) # get the parameters of attribute (by Attribute instance)
()
>>> n2.attr_params('dimension') # get the parameters of attribute (by name)
(5, 3)
>>> n2.attr_params(pointer_const) is None
True
"""
__slots__ = ('attrs',)
defaults = {'attrs': Tuple()} # type: Dict[str, Any]
_construct_attrs = staticmethod(_mk_Tuple)
def attr_params(self, looking_for):
""" Returns the parameters of the Attribute with name ``looking_for`` in self.attrs """
for attr in self.attrs:
if str(attr.name) == str(looking_for):
return attr.parameters
class Type(Token):
""" Represents a type.
Explanation
===========
The naming is a super-set of NumPy naming. Type has a classmethod
``from_expr`` which offer type deduction. It also has a method
``cast_check`` which casts the argument to its type, possibly raising an
exception if rounding error is not within tolerances, or if the value is not
representable by the underlying data type (e.g. unsigned integers).
Parameters
==========
name : str
Name of the type, e.g. ``object``, ``int16``, ``float16`` (where the latter two
would use the ``Type`` sub-classes ``IntType`` and ``FloatType`` respectively).
If a ``Type`` instance is given, the said instance is returned.
Examples
========
>>> from sympy.codegen.ast import Type
>>> t = Type.from_expr(42)
>>> t
integer
>>> print(repr(t))
IntBaseType(String('integer'))
>>> from sympy.codegen.ast import uint8
>>> uint8.cast_check(-1) # doctest: +ELLIPSIS
Traceback (most recent call last):
...
ValueError: Minimum value for data type bigger than new value.
>>> from sympy.codegen.ast import float32
>>> v6 = 0.123456
>>> float32.cast_check(v6)
0.123456
>>> v10 = 12345.67894
>>> float32.cast_check(v10) # doctest: +ELLIPSIS
Traceback (most recent call last):
...
ValueError: Casting gives a significantly different value.
>>> boost_mp50 = Type('boost::multiprecision::cpp_dec_float_50')
>>> from sympy.printing import cxxcode
>>> from sympy.codegen.ast import Declaration, Variable
>>> cxxcode(Declaration(Variable('x', type=boost_mp50)))
'boost::multiprecision::cpp_dec_float_50 x'
References
==========
.. [1] https://docs.scipy.org/doc/numpy/user/basics.types.html
"""
__slots__ = ('name',)
_construct_name = String
def _sympystr(self, printer, *args, **kwargs):
return str(self.name)
@classmethod
def from_expr(cls, expr):
""" Deduces type from an expression or a ``Symbol``.
Parameters
==========
expr : number or SymPy object
The type will be deduced from type or properties.
Examples
========
>>> from sympy.codegen.ast import Type, integer, complex_
>>> Type.from_expr(2) == integer
True
>>> from sympy import Symbol
>>> Type.from_expr(Symbol('z', complex=True)) == complex_
True
>>> Type.from_expr(sum) # doctest: +ELLIPSIS
Traceback (most recent call last):
...
ValueError: Could not deduce type from expr.
Raises
======
ValueError when type deduction fails.
"""
if isinstance(expr, (float, Float)):
return real
if isinstance(expr, (int, Integer)) or getattr(expr, 'is_integer', False):
return integer
if getattr(expr, 'is_real', False):
return real
if isinstance(expr, complex) or getattr(expr, 'is_complex', False):
return complex_
if isinstance(expr, bool) or getattr(expr, 'is_Relational', False):
return bool_
else:
raise ValueError("Could not deduce type from expr.")
def _check(self, value):
pass
def cast_check(self, value, rtol=None, atol=0, precision_targets=None):
""" Casts a value to the data type of the instance.
Parameters
==========
value : number
rtol : floating point number
Relative tolerance. (will be deduced if not given).
atol : floating point number
Absolute tolerance (in addition to ``rtol``).
type_aliases : dict
Maps substitutions for Type, e.g. {integer: int64, real: float32}
Examples
========
>>> from sympy.codegen.ast import integer, float32, int8
>>> integer.cast_check(3.0) == 3
True
>>> float32.cast_check(1e-40) # doctest: +ELLIPSIS
Traceback (most recent call last):
...
ValueError: Minimum value for data type bigger than new value.
>>> int8.cast_check(256) # doctest: +ELLIPSIS
Traceback (most recent call last):
...
ValueError: Maximum value for data type smaller than new value.
>>> v10 = 12345.67894
>>> float32.cast_check(v10) # doctest: +ELLIPSIS
Traceback (most recent call last):
...
ValueError: Casting gives a significantly different value.
>>> from sympy.codegen.ast import float64
>>> float64.cast_check(v10)
12345.67894
>>> from sympy import Float
>>> v18 = Float('0.123456789012345646')
>>> float64.cast_check(v18)
Traceback (most recent call last):
...
ValueError: Casting gives a significantly different value.
>>> from sympy.codegen.ast import float80
>>> float80.cast_check(v18)
0.123456789012345649
"""
val = sympify(value)
ten = Integer(10)
exp10 = getattr(self, 'decimal_dig', None)
if rtol is None:
rtol = 1e-15 if exp10 is None else 2.0*ten**(-exp10)
def tol(num):
return atol + rtol*abs(num)
new_val = self.cast_nocheck(value)
self._check(new_val)
delta = new_val - val
if abs(delta) > tol(val): # rounding, e.g. int(3.5) != 3.5
raise ValueError("Casting gives a significantly different value.")
return new_val
class IntBaseType(Type):
""" Integer base type, contains no size information. """
__slots__ = ('name',)
cast_nocheck = lambda self, i: Integer(int(i))
class _SizedIntType(IntBaseType):
__slots__ = ('name', 'nbits',)
_construct_nbits = Integer
def _check(self, value):
if value < self.min:
raise ValueError("Value is too small: %d < %d" % (value, self.min))
if value > self.max:
raise ValueError("Value is too big: %d > %d" % (value, self.max))
class SignedIntType(_SizedIntType):
""" Represents a signed integer type. """
@property
def min(self):
return -2**(self.nbits-1)
@property
def max(self):
return 2**(self.nbits-1) - 1
class UnsignedIntType(_SizedIntType):
""" Represents an unsigned integer type. """
@property
def min(self):
return 0
@property
def max(self):
return 2**self.nbits - 1
two = Integer(2)
class FloatBaseType(Type):
""" Represents a floating point number type. """
cast_nocheck = Float
class FloatType(FloatBaseType):
""" Represents a floating point type with fixed bit width.
Base 2 & one sign bit is assumed.
Parameters
==========
name : str
Name of the type.
nbits : integer
Number of bits used (storage).
nmant : integer
Number of bits used to represent the mantissa.
nexp : integer
Number of bits used to represent the mantissa.
Examples
========
>>> from sympy import S
>>> from sympy.codegen.ast import FloatType
>>> half_precision = FloatType('f16', nbits=16, nmant=10, nexp=5)
>>> half_precision.max
65504
>>> half_precision.tiny == S(2)**-14
True
>>> half_precision.eps == S(2)**-10
True
>>> half_precision.dig == 3
True
>>> half_precision.decimal_dig == 5
True
>>> half_precision.cast_check(1.0)
1.0
>>> half_precision.cast_check(1e5) # doctest: +ELLIPSIS
Traceback (most recent call last):
...
ValueError: Maximum value for data type smaller than new value.
"""
__slots__ = ('name', 'nbits', 'nmant', 'nexp',)
_construct_nbits = _construct_nmant = _construct_nexp = Integer
@property
def max_exponent(self):
""" The largest positive number n, such that 2**(n - 1) is a representable finite value. """
# cf. C++'s ``std::numeric_limits::max_exponent``
return two**(self.nexp - 1)
@property
def min_exponent(self):
""" The lowest negative number n, such that 2**(n - 1) is a valid normalized number. """
# cf. C++'s ``std::numeric_limits::min_exponent``
return 3 - self.max_exponent
@property
def max(self):
""" Maximum value representable. """
return (1 - two**-(self.nmant+1))*two**self.max_exponent
@property
def tiny(self):
""" The minimum positive normalized value. """
# See C macros: FLT_MIN, DBL_MIN, LDBL_MIN
# or C++'s ``std::numeric_limits::min``
# or numpy.finfo(dtype).tiny
return two**(self.min_exponent - 1)
@property
def eps(self):
""" Difference between 1.0 and the next representable value. """
return two**(-self.nmant)
@property
def dig(self):
""" Number of decimal digits that are guaranteed to be preserved in text.
When converting text -> float -> text, you are guaranteed that at least ``dig``
number of digits are preserved with respect to rounding or overflow.
"""
from sympy.functions import floor, log
return floor(self.nmant * log(2)/log(10))
@property
def decimal_dig(self):
""" Number of digits needed to store & load without loss.
Explanation
===========
Number of decimal digits needed to guarantee that two consecutive conversions
(float -> text -> float) to be idempotent. This is useful when one do not want
to loose precision due to rounding errors when storing a floating point value
as text.
"""
from sympy.functions import ceiling, log
return ceiling((self.nmant + 1) * log(2)/log(10) + 1)
def cast_nocheck(self, value):
""" Casts without checking if out of bounds or subnormal. """
if value == oo: # float(oo) or oo
return float(oo)
elif value == -oo: # float(-oo) or -oo
return float(-oo)
return Float(str(sympify(value).evalf(self.decimal_dig)), self.decimal_dig)
def _check(self, value):
if value < -self.max:
raise ValueError("Value is too small: %d < %d" % (value, -self.max))
if value > self.max:
raise ValueError("Value is too big: %d > %d" % (value, self.max))
if abs(value) < self.tiny:
raise ValueError("Smallest (absolute) value for data type bigger than new value.")
class ComplexBaseType(FloatBaseType):
def cast_nocheck(self, value):
""" Casts without checking if out of bounds or subnormal. """
from sympy.functions import re, im
return (
super().cast_nocheck(re(value)) +
super().cast_nocheck(im(value))*1j
)
def _check(self, value):
from sympy.functions import re, im
super()._check(re(value))
super()._check(im(value))
class ComplexType(ComplexBaseType, FloatType):
""" Represents a complex floating point number. """
# NumPy types:
intc = IntBaseType('intc')
intp = IntBaseType('intp')
int8 = SignedIntType('int8', 8)
int16 = SignedIntType('int16', 16)
int32 = SignedIntType('int32', 32)
int64 = SignedIntType('int64', 64)
uint8 = UnsignedIntType('uint8', 8)
uint16 = UnsignedIntType('uint16', 16)
uint32 = UnsignedIntType('uint32', 32)
uint64 = UnsignedIntType('uint64', 64)
float16 = FloatType('float16', 16, nexp=5, nmant=10) # IEEE 754 binary16, Half precision
float32 = FloatType('float32', 32, nexp=8, nmant=23) # IEEE 754 binary32, Single precision
float64 = FloatType('float64', 64, nexp=11, nmant=52) # IEEE 754 binary64, Double precision
float80 = FloatType('float80', 80, nexp=15, nmant=63) # x86 extended precision (1 integer part bit), "long double"
float128 = FloatType('float128', 128, nexp=15, nmant=112) # IEEE 754 binary128, Quadruple precision
float256 = FloatType('float256', 256, nexp=19, nmant=236) # IEEE 754 binary256, Octuple precision
complex64 = ComplexType('complex64', nbits=64, **float32.kwargs(exclude=('name', 'nbits')))
complex128 = ComplexType('complex128', nbits=128, **float64.kwargs(exclude=('name', 'nbits')))
# Generic types (precision may be chosen by code printers):
untyped = Type('untyped')
real = FloatBaseType('real')
integer = IntBaseType('integer')
complex_ = ComplexBaseType('complex')
bool_ = Type('bool')
class Attribute(Token):
""" Attribute (possibly parametrized)
For use with :class:`sympy.codegen.ast.Node` (which takes instances of
``Attribute`` as ``attrs``).
Parameters
==========
name : str
parameters : Tuple
Examples
========
>>> from sympy.codegen.ast import Attribute
>>> volatile = Attribute('volatile')
>>> volatile
volatile
>>> print(repr(volatile))
Attribute(String('volatile'))
>>> a = Attribute('foo', [1, 2, 3])
>>> a
foo(1, 2, 3)
>>> a.parameters == (1, 2, 3)
True
"""
__slots__ = ('name', 'parameters')
defaults = {'parameters': Tuple()}
_construct_name = String
_construct_parameters = staticmethod(_mk_Tuple)
def _sympystr(self, printer, *args, **kwargs):
result = str(self.name)
if self.parameters:
result += '(%s)' % ', '.join(map(lambda arg: printer._print(
arg, *args, **kwargs), self.parameters))
return result
value_const = Attribute('value_const')
pointer_const = Attribute('pointer_const')
class Variable(Node):
""" Represents a variable.
Parameters
==========
symbol : Symbol
type : Type (optional)
Type of the variable.
attrs : iterable of Attribute instances
Will be stored as a Tuple.
Examples
========
>>> from sympy import Symbol
>>> from sympy.codegen.ast import Variable, float32, integer
>>> x = Symbol('x')
>>> v = Variable(x, type=float32)
>>> v.attrs
()
>>> v == Variable('x')
False
>>> v == Variable('x', type=float32)
True
>>> v
Variable(x, type=float32)
One may also construct a ``Variable`` instance with the type deduced from
assumptions about the symbol using the ``deduced`` classmethod:
>>> i = Symbol('i', integer=True)
>>> v = Variable.deduced(i)
>>> v.type == integer
True
>>> v == Variable('i')
False
>>> from sympy.codegen.ast import value_const
>>> value_const in v.attrs
False
>>> w = Variable('w', attrs=[value_const])
>>> w
Variable(w, attrs=(value_const,))
>>> value_const in w.attrs
True
>>> w.as_Declaration(value=42)
Declaration(Variable(w, value=42, attrs=(value_const,)))
"""
__slots__ = ('symbol', 'type', 'value') + Node.__slots__
defaults = Node.defaults.copy()
defaults.update({'type': untyped, 'value': none})
_construct_symbol = staticmethod(sympify)
_construct_value = staticmethod(sympify)
@classmethod
def deduced(cls, symbol, value=None, attrs=Tuple(), cast_check=True):
""" Alt. constructor with type deduction from ``Type.from_expr``.
Deduces type primarily from ``symbol``, secondarily from ``value``.
Parameters
==========
symbol : Symbol
value : expr
(optional) value of the variable.
attrs : iterable of Attribute instances
cast_check : bool
Whether to apply ``Type.cast_check`` on ``value``.
Examples
========
>>> from sympy import Symbol
>>> from sympy.codegen.ast import Variable, complex_
>>> n = Symbol('n', integer=True)
>>> str(Variable.deduced(n).type)
'integer'
>>> x = Symbol('x', real=True)
>>> v = Variable.deduced(x)
>>> v.type
real
>>> z = Symbol('z', complex=True)
>>> Variable.deduced(z).type == complex_
True
"""
if isinstance(symbol, Variable):
return symbol
try:
type_ = Type.from_expr(symbol)
except ValueError:
type_ = Type.from_expr(value)
if value is not None and cast_check:
value = type_.cast_check(value)
return cls(symbol, type=type_, value=value, attrs=attrs)
def as_Declaration(self, **kwargs):
""" Convenience method for creating a Declaration instance.
Explanation
===========
If the variable of the Declaration need to wrap a modified
variable keyword arguments may be passed (overriding e.g.
the ``value`` of the Variable instance).
Examples
========
>>> from sympy.codegen.ast import Variable, NoneToken
>>> x = Variable('x')
>>> decl1 = x.as_Declaration()
>>> # value is special NoneToken() which must be tested with == operator
>>> decl1.variable.value is None # won't work
False
>>> decl1.variable.value == None # not PEP-8 compliant
True
>>> decl1.variable.value == NoneToken() # OK
True
>>> decl2 = x.as_Declaration(value=42.0)
>>> decl2.variable.value == 42
True
"""
kw = self.kwargs()
kw.update(kwargs)
return Declaration(self.func(**kw))
def _relation(self, rhs, op):
try:
rhs = _sympify(rhs)
except SympifyError:
raise TypeError("Invalid comparison %s < %s" % (self, rhs))
return op(self, rhs, evaluate=False)
__lt__ = lambda self, other: self._relation(other, Lt)
__le__ = lambda self, other: self._relation(other, Le)
__ge__ = lambda self, other: self._relation(other, Ge)
__gt__ = lambda self, other: self._relation(other, Gt)
class Pointer(Variable):
""" Represents a pointer. See ``Variable``.
Examples
========
Can create instances of ``Element``:
>>> from sympy import Symbol
>>> from sympy.codegen.ast import Pointer
>>> i = Symbol('i', integer=True)
>>> p = Pointer('x')
>>> p[i+1]
Element(x, indices=(i + 1,))
"""
def __getitem__(self, key):
try:
return Element(self.symbol, key)
except TypeError:
return Element(self.symbol, (key,))
class Element(Token):
""" Element in (a possibly N-dimensional) array.
Examples
========
>>> from sympy.codegen.ast import Element
>>> elem = Element('x', 'ijk')
>>> elem.symbol.name == 'x'
True
>>> elem.indices
(i, j, k)
>>> from sympy import ccode
>>> ccode(elem)
'x[i][j][k]'
>>> ccode(Element('x', 'ijk', strides='lmn', offset='o'))
'x[i*l + j*m + k*n + o]'
"""
__slots__ = ('symbol', 'indices', 'strides', 'offset')
defaults = {'strides': none, 'offset': none}
_construct_symbol = staticmethod(sympify)
_construct_indices = staticmethod(lambda arg: Tuple(*arg))
_construct_strides = staticmethod(lambda arg: Tuple(*arg))
_construct_offset = staticmethod(sympify)
class Declaration(Token):
""" Represents a variable declaration
Parameters
==========
variable : Variable
Examples
========
>>> from sympy.codegen.ast import Declaration, NoneToken, untyped
>>> z = Declaration('z')
>>> z.variable.type == untyped
True
>>> # value is special NoneToken() which must be tested with == operator
>>> z.variable.value is None # won't work
False
>>> z.variable.value == None # not PEP-8 compliant
True
>>> z.variable.value == NoneToken() # OK
True
"""
__slots__ = ('variable',)
_construct_variable = Variable
class While(Token):
""" Represents a 'for-loop' in the code.
Expressions are of the form:
"while condition:
body..."
Parameters
==========
condition : expression convertible to Boolean
body : CodeBlock or iterable
When passed an iterable it is used to instantiate a CodeBlock.
Examples
========
>>> from sympy import symbols, Gt, Abs
>>> from sympy.codegen import aug_assign, Assignment, While
>>> x, dx = symbols('x dx')
>>> expr = 1 - x**2
>>> whl = While(Gt(Abs(dx), 1e-9), [
... Assignment(dx, -expr/expr.diff(x)),
... aug_assign(x, '+', dx)
... ])
"""
__slots__ = ('condition', 'body')
_construct_condition = staticmethod(lambda cond: _sympify(cond))
@classmethod
def _construct_body(cls, itr):
if isinstance(itr, CodeBlock):
return itr
else:
return CodeBlock(*itr)
class Scope(Token):
""" Represents a scope in the code.
Parameters
==========
body : CodeBlock or iterable
When passed an iterable it is used to instantiate a CodeBlock.
"""
__slots__ = ('body',)
@classmethod
def _construct_body(cls, itr):
if isinstance(itr, CodeBlock):
return itr
else:
return CodeBlock(*itr)
class Stream(Token):
""" Represents a stream.
There are two predefined Stream instances ``stdout`` & ``stderr``.
Parameters
==========
name : str
Examples
========
>>> from sympy import Symbol
>>> from sympy.printing.pycode import pycode
>>> from sympy.codegen.ast import Print, stderr, QuotedString
>>> print(pycode(Print(['x'], file=stderr)))
print(x, file=sys.stderr)
>>> x = Symbol('x')
>>> print(pycode(Print([QuotedString('x')], file=stderr))) # print literally "x"
print("x", file=sys.stderr)
"""
__slots__ = ('name',)
_construct_name = String
stdout = Stream('stdout')
stderr = Stream('stderr')
class Print(Token):
""" Represents print command in the code.
Parameters
==========
formatstring : str
*args : Basic instances (or convertible to such through sympify)
Examples
========
>>> from sympy.codegen.ast import Print
>>> from sympy.printing.pycode import pycode
>>> print(pycode(Print('x y'.split(), "coordinate: %12.5g %12.5g")))
print("coordinate: %12.5g %12.5g" % (x, y))
"""
__slots__ = ('print_args', 'format_string', 'file')
defaults = {'format_string': none, 'file': none}
_construct_print_args = staticmethod(_mk_Tuple)
_construct_format_string = QuotedString
_construct_file = Stream
class FunctionPrototype(Node):
""" Represents a function prototype
Allows the user to generate forward declaration in e.g. C/C++.
Parameters
==========
return_type : Type
name : str
parameters: iterable of Variable instances
attrs : iterable of Attribute instances
Examples
========
>>> from sympy import symbols
>>> from sympy.codegen.ast import real, FunctionPrototype
>>> from sympy.printing import ccode
>>> x, y = symbols('x y', real=True)
>>> fp = FunctionPrototype(real, 'foo', [x, y])
>>> ccode(fp)
'double foo(double x, double y)'
"""
__slots__ = ('return_type', 'name', 'parameters', 'attrs')
_construct_return_type = Type
_construct_name = String
@staticmethod
def _construct_parameters(args):
def _var(arg):
if isinstance(arg, Declaration):
return arg.variable
elif isinstance(arg, Variable):
return arg
else:
return Variable.deduced(arg)
return Tuple(*map(_var, args))
@classmethod
def from_FunctionDefinition(cls, func_def):
if not isinstance(func_def, FunctionDefinition):
raise TypeError("func_def is not an instance of FunctionDefiniton")
return cls(**func_def.kwargs(exclude=('body',)))
class FunctionDefinition(FunctionPrototype):
""" Represents a function definition in the code.
Parameters
==========
return_type : Type
name : str
parameters: iterable of Variable instances
body : CodeBlock or iterable
attrs : iterable of Attribute instances
Examples
========
>>> from sympy import symbols
>>> from sympy.codegen.ast import real, FunctionPrototype
>>> from sympy.printing import ccode
>>> x, y = symbols('x y', real=True)
>>> fp = FunctionPrototype(real, 'foo', [x, y])
>>> ccode(fp)
'double foo(double x, double y)'
>>> from sympy.codegen.ast import FunctionDefinition, Return
>>> body = [Return(x*y)]
>>> fd = FunctionDefinition.from_FunctionPrototype(fp, body)
>>> print(ccode(fd))
double foo(double x, double y){
return x*y;
}
"""
__slots__ = FunctionPrototype.__slots__[:-1] + ('body', 'attrs')
@classmethod
def _construct_body(cls, itr):
if isinstance(itr, CodeBlock):
return itr
else:
return CodeBlock(*itr)
@classmethod
def from_FunctionPrototype(cls, func_proto, body):
if not isinstance(func_proto, FunctionPrototype):
raise TypeError("func_proto is not an instance of FunctionPrototype")
return cls(body=body, **func_proto.kwargs())
class Return(Basic):
""" Represents a return command in the code. """
class FunctionCall(Token, Expr):
""" Represents a call to a function in the code.
Parameters
==========
name : str
function_args : Tuple
Examples
========
>>> from sympy.codegen.ast import FunctionCall
>>> from sympy.printing.pycode import pycode
>>> fcall = FunctionCall('foo', 'bar baz'.split())
>>> print(pycode(fcall))
foo(bar, baz)
"""
__slots__ = ('name', 'function_args')
_construct_name = String
_construct_function_args = staticmethod(lambda args: Tuple(*args))
|
f58d9a34ab3820037630e570978dd6bc095008aa7c94a4ee6f2673b4c58e4263 | """A module which implements predicates and assumption context."""
from contextlib import contextmanager
import inspect
from sympy.core.assumptions import ManagedProperties
from sympy.core.symbol import Str
from sympy.core.sympify import _sympify
from sympy.logic.boolalg import Boolean, false, true
from sympy.multipledispatch.dispatcher import Dispatcher, str_signature
from sympy.utilities.exceptions import SymPyDeprecationWarning
from sympy.utilities.iterables import is_sequence
from sympy.utilities.source import get_class
class AssumptionsContext(set):
"""
Set containing default assumptions which are applied to the ``ask()``
function.
Explanation
===========
This is used to represent global assumptions, but you can also use this
class to create your own local assumptions contexts. It is basically a thin
wrapper to Python's set, so see its documentation for advanced usage.
Examples
========
The default assumption context is ``global_assumptions``, which is initially empty:
>>> from sympy import ask, Q
>>> from sympy.assumptions import global_assumptions
>>> global_assumptions
AssumptionsContext()
You can add default assumptions:
>>> from sympy.abc import x
>>> global_assumptions.add(Q.real(x))
>>> global_assumptions
AssumptionsContext({Q.real(x)})
>>> ask(Q.real(x))
True
And remove them:
>>> global_assumptions.remove(Q.real(x))
>>> print(ask(Q.real(x)))
None
The ``clear()`` method removes every assumption:
>>> global_assumptions.add(Q.positive(x))
>>> global_assumptions
AssumptionsContext({Q.positive(x)})
>>> global_assumptions.clear()
>>> global_assumptions
AssumptionsContext()
See Also
========
assuming
"""
def add(self, *assumptions):
"""Add assumptions."""
for a in assumptions:
super().add(a)
def _sympystr(self, printer):
if not self:
return "%s()" % self.__class__.__name__
return "{}({})".format(self.__class__.__name__, printer._print_set(self))
global_assumptions = AssumptionsContext()
class AppliedPredicate(Boolean):
"""
The class of expressions resulting from applying ``Predicate`` to
the arguments. ``AppliedPredicate`` merely wraps its argument and
remain unevaluated. To evaluate it, use the ``ask()`` function.
Examples
========
>>> from sympy import Q, ask
>>> Q.integer(1)
Q.integer(1)
The ``function`` attribute returns the predicate, and the ``arguments``
attribute returns the tuple of arguments.
>>> type(Q.integer(1))
<class 'sympy.assumptions.assume.AppliedPredicate'>
>>> Q.integer(1).function
Q.integer
>>> Q.integer(1).arguments
(1,)
Applied predicates can be evaluated to a boolean value with ``ask``:
>>> ask(Q.integer(1))
True
"""
__slots__ = ()
def __new__(cls, predicate, *args):
if not isinstance(predicate, Predicate):
raise TypeError("%s is not a Predicate." % predicate)
args = map(_sympify, args)
return super().__new__(cls, predicate, *args)
@property
def arg(self):
"""
Return the expression used by this assumption.
Examples
========
>>> from sympy import Q, Symbol
>>> x = Symbol('x')
>>> a = Q.integer(x + 1)
>>> a.arg
x + 1
"""
# Will be deprecated
args = self._args
if len(args) == 2:
# backwards compatibility
return args[1]
raise TypeError("'arg' property is allowed only for unary predicates.")
@property
def function(self):
"""
Return the predicate.
"""
# Will be changed to self.args[0] after args overridding is removed
return self._args[0]
@property
def arguments(self):
"""
Return the arguments which are applied to the predicate.
"""
# Will be changed to self.args[1:] after args overridding is removed
return self._args[1:]
def _eval_ask(self, assumptions):
return self.function.eval(self.arguments, assumptions)
@property
def binary_symbols(self):
from .ask import Q
if self.function == Q.is_true:
i = self.arguments[0]
if i.is_Boolean or i.is_Symbol:
return i.binary_symbols
if self.function in (Q.eq, Q.ne):
if true in self.arguments or false in self.arguments:
if self.arguments[0].is_Symbol:
return {self.arguments[0]}
elif self.arguments[1].is_Symbol:
return {self.arguments[1]}
return set()
class PredicateMeta(ManagedProperties):
def __new__(cls, clsname, bases, dct):
# If handler is not defined, assign empty dispatcher.
if "handler" not in dct:
name = f"Ask{clsname.capitalize()}Handler"
handler = Dispatcher(name, doc="Handler for key %s" % name)
dct["handler"] = handler
dct["_orig_doc"] = dct.get("__doc__", "")
return super().__new__(cls, clsname, bases, dct)
@property
def __doc__(cls):
handler = cls.handler
doc = cls._orig_doc
if cls is not Predicate and handler is not None:
doc += "Handler\n"
doc += " =======\n\n"
# Append the handler's doc without breaking sphinx documentation.
docs = [" Multiply dispatched method: %s" % handler.name]
if handler.doc:
for line in handler.doc.splitlines():
if not line:
continue
docs.append(" %s" % line)
other = []
for sig in handler.ordering[::-1]:
func = handler.funcs[sig]
if func.__doc__:
s = ' Inputs: <%s>' % str_signature(sig)
lines = []
for line in func.__doc__.splitlines():
lines.append(" %s" % line)
s += "\n".join(lines)
docs.append(s)
else:
other.append(str_signature(sig))
if other:
othersig = " Other signatures:"
for line in other:
othersig += "\n * %s" % line
docs.append(othersig)
doc += '\n\n'.join(docs)
return doc
class Predicate(Boolean, metaclass=PredicateMeta):
"""
Base class for mathematical predicates. It also serves as a
constructor for undefined predicate objects.
Explanation
===========
Predicate is a function that returns a boolean value [1].
Predicate function is object, and it is instance of predicate class.
When a predicate is applied to arguments, ``AppliedPredicate``
instance is returned. This merely wraps the argument and remain
unevaluated. To obtain the truth value of applied predicate, use the
function ``ask``.
Evaluation of predicate is done by multiple dispatching. You can
register new handler to the predicate to support new types.
Every predicate in SymPy can be accessed via the property of ``Q``.
For example, ``Q.even`` returns the predicate which checks if the
argument is even number.
To define a predicate which can be evaluated, you must subclass this
class, make an instance of it, and register it to ``Q``. After then,
dispatch the handler by argument types.
If you directly construct predicate using this class, you will get
``UndefinedPredicate`` which cannot be dispatched. This is useful
when you are building boolean expressions which do not need to be
evaluated.
Examples
========
Applying and evaluating to boolean value:
>>> from sympy import Q, ask
>>> ask(Q.prime(7))
True
You can define a new predicate by subclassing and dispatching. Here,
we define a predicate for sexy primes [2] as an example.
>>> from sympy import Predicate, Integer
>>> class SexyPrimePredicate(Predicate):
... name = "sexyprime"
>>> Q.sexyprime = SexyPrimePredicate()
>>> @Q.sexyprime.register(Integer, Integer)
... def _(int1, int2, assumptions):
... args = sorted([int1, int2])
... if not all(ask(Q.prime(a), assumptions) for a in args):
... return False
... return args[1] - args[0] == 6
>>> ask(Q.sexyprime(5, 11))
True
Direct constructing returns ``UndefinedPredicate``, which can be
applied but cannot be dispatched.
>>> from sympy import Predicate, Integer
>>> Q.P = Predicate("P")
>>> type(Q.P)
<class 'sympy.assumptions.assume.UndefinedPredicate'>
>>> Q.P(1)
Q.P(1)
>>> Q.P.register(Integer)(lambda expr, assump: True)
Traceback (most recent call last):
...
TypeError: <class 'sympy.assumptions.assume.UndefinedPredicate'> cannot be dispatched.
References
==========
.. [1] https://en.wikipedia.org/wiki/Predicate_(mathematical_logic)
.. [2] https://en.wikipedia.org/wiki/Sexy_prime
"""
is_Atom = True
def __new__(cls, *args, **kwargs):
if cls is Predicate:
return UndefinedPredicate(*args, **kwargs)
obj = super().__new__(cls, *args)
return obj
@property
def name(self):
# May be overridden
return type(self).__name__
@classmethod
def register(cls, *types, **kwargs):
"""
Register the signature to the handler.
"""
if cls.handler is None:
raise TypeError("%s cannot be dispatched." % type(cls))
return cls.handler.register(*types, **kwargs)
@classmethod
def register_many(cls, *types, **kwargs):
"""
Register multiple signatures to same handler.
"""
def _(func):
for t in types:
if not is_sequence(t):
t = (t,) # for convenience, allow passing `type` to mean `(type,)`
cls.register(*t, **kwargs)(func)
return _
def __call__(self, *args):
return AppliedPredicate(self, *args)
def eval(self, args, assumptions=True):
"""
Evaluate ``self(*args)`` under the given assumptions.
This uses only direct resolution methods, not logical inference.
"""
result = None
try:
result = self.handler(*args, assumptions=assumptions)
except NotImplementedError:
pass
return result
def _eval_refine(self, assumptions):
# When Predicate is no longer Boolean, delete this method
return self
class UndefinedPredicate(Predicate):
"""
Predicate without handler.
Explanation
===========
This predicate is generated by using ``Predicate`` directly for
construction. It does not have a handler, and evaluating this with
arguments is done by SAT solver.
Examples
========
>>> from sympy import Predicate, Q
>>> Q.P = Predicate('P')
>>> Q.P.func
<class 'sympy.assumptions.assume.UndefinedPredicate'>
>>> Q.P.name
Str('P')
"""
handler = None
def __new__(cls, name, handlers=None):
# "handlers" parameter supports old design
if not isinstance(name, Str):
name = Str(name)
obj = super(Boolean, cls).__new__(cls, name)
obj.handlers = handlers or []
return obj
@property
def name(self):
return self.args[0]
def _hashable_content(self):
return (self.name,)
def __getnewargs__(self):
return (self.name,)
def __call__(self, expr):
return AppliedPredicate(self, expr)
def add_handler(self, handler):
SymPyDeprecationWarning(
feature="Predicate.add_handler() method",
useinstead="multipledispatch handler of Predicate",
issue=20873,
deprecated_since_version="1.8"
).warn()
self.handlers.append(handler)
def remove_handler(self, handler):
SymPyDeprecationWarning(
feature="Predicate.remove_handler() method",
useinstead="multipledispatch handler of Predicate",
issue=20873,
deprecated_since_version="1.8"
).warn()
self.handlers.remove(handler)
def eval(self, args, assumptions=True):
# Support for deprecated design
# When old design is removed, this will always return None
SymPyDeprecationWarning(
feature="Evaluating UndefinedPredicate",
useinstead="multipledispatch handler of Predicate",
issue=20873,
deprecated_since_version="1.8"
).warn()
expr, = args
res, _res = None, None
mro = inspect.getmro(type(expr))
for handler in self.handlers:
cls = get_class(handler)
for subclass in mro:
eval_ = getattr(cls, subclass.__name__, None)
if eval_ is None:
continue
res = eval_(expr, assumptions)
# Do not stop if value returned is None
# Try to check for higher classes
if res is None:
continue
if _res is None:
_res = res
else:
# only check consistency if both resolutors have concluded
if _res != res:
raise ValueError('incompatible resolutors')
break
return res
@contextmanager
def assuming(*assumptions):
"""
Context manager for assumptions.
Examples
========
>>> from sympy.assumptions import assuming, Q, ask
>>> from sympy.abc import x, y
>>> print(ask(Q.integer(x + y)))
None
>>> with assuming(Q.integer(x), Q.integer(y)):
... print(ask(Q.integer(x + y)))
True
"""
old_global_assumptions = global_assumptions.copy()
global_assumptions.update(assumptions)
try:
yield
finally:
global_assumptions.clear()
global_assumptions.update(old_global_assumptions)
|
4b7564be0d56506a12c6b4161ec0ec12ffb41d5e3b2978b977411b72f65d104a | """
This module contains functions to:
- solve a single equation for a single variable, in any domain either real or complex.
- solve a single transcendental equation for a single variable in any domain either real or complex.
(currently supports solving in real domain only)
- solve a system of linear equations with N variables and M equations.
- solve a system of Non Linear Equations with N variables and M equations
"""
from sympy.core.sympify import sympify
from sympy.core import (S, Pow, Dummy, pi, Expr, Wild, Mul, Equality,
Add)
from sympy.core.containers import Tuple
from sympy.core.numbers import I, Number, Rational, oo
from sympy.core.function import (Lambda, expand_complex, AppliedUndef,
expand_log)
from sympy.core.mod import Mod
from sympy.core.numbers import igcd
from sympy.core.relational import Eq, Ne, Relational
from sympy.core.symbol import Symbol, _uniquely_named_symbol
from sympy.core.sympify import _sympify
from sympy.simplify.simplify import simplify, fraction, trigsimp
from sympy.simplify import powdenest, logcombine
from sympy.functions import (log, Abs, tan, cot, sin, cos, sec, csc, exp,
acos, asin, acsc, asec, arg,
piecewise_fold, Piecewise)
from sympy.functions.elementary.trigonometric import (TrigonometricFunction,
HyperbolicFunction)
from sympy.functions.elementary.miscellaneous import real_root
from sympy.logic.boolalg import And
from sympy.sets import (FiniteSet, EmptySet, imageset, Interval, Intersection,
Union, ConditionSet, ImageSet, Complement, Contains)
from sympy.sets.sets import Set, ProductSet
from sympy.matrices import Matrix, MatrixBase
from sympy.ntheory import totient
from sympy.ntheory.factor_ import divisors
from sympy.ntheory.residue_ntheory import discrete_log, nthroot_mod
from sympy.polys import (roots, Poly, degree, together, PolynomialError,
RootOf, factor, lcm, gcd)
from sympy.polys.polyerrors import CoercionFailed
from sympy.polys.polytools import invert
from sympy.polys.solvers import (sympy_eqs_to_ring, solve_lin_sys,
PolyNonlinearError)
from sympy.polys.matrices.linsolve import _linsolve
from sympy.solvers.solvers import (checksol, denoms, unrad,
_simple_dens, recast_to_symbols)
from sympy.solvers.polysys import solve_poly_system
from sympy.solvers.inequalities import solve_univariate_inequality
from sympy.utilities import filldedent
from sympy.utilities.iterables import numbered_symbols, has_dups
from sympy.calculus.util import periodicity, continuous_domain
from sympy.core.compatibility import ordered, default_sort_key, is_sequence
from types import GeneratorType
from collections import defaultdict
class NonlinearError(ValueError):
"""Raised when unexpectedly encountering nonlinear equations"""
pass
_rc = Dummy("R", real=True), Dummy("C", complex=True)
def _masked(f, *atoms):
"""Return ``f``, with all objects given by ``atoms`` replaced with
Dummy symbols, ``d``, and the list of replacements, ``(d, e)``,
where ``e`` is an object of type given by ``atoms`` in which
any other instances of atoms have been recursively replaced with
Dummy symbols, too. The tuples are ordered so that if they are
applied in sequence, the origin ``f`` will be restored.
Examples
========
>>> from sympy import cos
>>> from sympy.abc import x
>>> from sympy.solvers.solveset import _masked
>>> f = cos(cos(x) + 1)
>>> f, reps = _masked(cos(1 + cos(x)), cos)
>>> f
_a1
>>> reps
[(_a1, cos(_a0 + 1)), (_a0, cos(x))]
>>> for d, e in reps:
... f = f.xreplace({d: e})
>>> f
cos(cos(x) + 1)
"""
sym = numbered_symbols('a', cls=Dummy, real=True)
mask = []
for a in ordered(f.atoms(*atoms)):
for i in mask:
a = a.replace(*i)
mask.append((a, next(sym)))
for i, (o, n) in enumerate(mask):
f = f.replace(o, n)
mask[i] = (n, o)
mask = list(reversed(mask))
return f, mask
def _invert(f_x, y, x, domain=S.Complexes):
r"""
Reduce the complex valued equation ``f(x) = y`` to a set of equations
``{g(x) = h_1(y), g(x) = h_2(y), ..., g(x) = h_n(y) }`` where ``g(x)`` is
a simpler function than ``f(x)``. The return value is a tuple ``(g(x),
set_h)``, where ``g(x)`` is a function of ``x`` and ``set_h`` is
the set of function ``{h_1(y), h_2(y), ..., h_n(y)}``.
Here, ``y`` is not necessarily a symbol.
The ``set_h`` contains the functions, along with the information
about the domain in which they are valid, through set
operations. For instance, if ``y = Abs(x) - n`` is inverted
in the real domain, then ``set_h`` is not simply
`{-n, n}` as the nature of `n` is unknown; rather, it is:
`Intersection([0, oo) {n}) U Intersection((-oo, 0], {-n})`
By default, the complex domain is used which means that inverting even
seemingly simple functions like ``exp(x)`` will give very different
results from those obtained in the real domain.
(In the case of ``exp(x)``, the inversion via ``log`` is multi-valued
in the complex domain, having infinitely many branches.)
If you are working with real values only (or you are not sure which
function to use) you should probably set the domain to
``S.Reals`` (or use `invert\_real` which does that automatically).
Examples
========
>>> from sympy.solvers.solveset import invert_complex, invert_real
>>> from sympy.abc import x, y
>>> from sympy import exp
When does exp(x) == y?
>>> invert_complex(exp(x), y, x)
(x, ImageSet(Lambda(_n, I*(2*_n*pi + arg(y)) + log(Abs(y))), Integers))
>>> invert_real(exp(x), y, x)
(x, Intersection(FiniteSet(log(y)), Reals))
When does exp(x) == 1?
>>> invert_complex(exp(x), 1, x)
(x, ImageSet(Lambda(_n, 2*_n*I*pi), Integers))
>>> invert_real(exp(x), 1, x)
(x, FiniteSet(0))
See Also
========
invert_real, invert_complex
"""
x = sympify(x)
if not x.is_Symbol:
raise ValueError("x must be a symbol")
f_x = sympify(f_x)
if x not in f_x.free_symbols:
raise ValueError("Inverse of constant function doesn't exist")
y = sympify(y)
if x in y.free_symbols:
raise ValueError("y should be independent of x ")
if domain.is_subset(S.Reals):
x1, s = _invert_real(f_x, FiniteSet(y), x)
else:
x1, s = _invert_complex(f_x, FiniteSet(y), x)
if not isinstance(s, FiniteSet) or x1 != x:
return x1, s
# Avoid adding gratuitous intersections with S.Complexes. Actual
# conditions should be handled by the respective inverters.
if domain is S.Complexes:
return x1, s
else:
return x1, s.intersection(domain)
invert_complex = _invert
def invert_real(f_x, y, x, domain=S.Reals):
"""
Inverts a real-valued function. Same as _invert, but sets
the domain to ``S.Reals`` before inverting.
"""
return _invert(f_x, y, x, domain)
def _invert_real(f, g_ys, symbol):
"""Helper function for _invert."""
if f == symbol:
return (f, g_ys)
n = Dummy('n', real=True)
if isinstance(f, exp) or (f.is_Pow and f.base == S.Exp1):
return _invert_real(f.exp,
imageset(Lambda(n, log(n)), g_ys),
symbol)
if hasattr(f, 'inverse') and f.inverse() is not None and not isinstance(f, (
TrigonometricFunction,
HyperbolicFunction,
)):
if len(f.args) > 1:
raise ValueError("Only functions with one argument are supported.")
return _invert_real(f.args[0],
imageset(Lambda(n, f.inverse()(n)), g_ys),
symbol)
if isinstance(f, Abs):
return _invert_abs(f.args[0], g_ys, symbol)
if f.is_Add:
# f = g + h
g, h = f.as_independent(symbol)
if g is not S.Zero:
return _invert_real(h, imageset(Lambda(n, n - g), g_ys), symbol)
if f.is_Mul:
# f = g*h
g, h = f.as_independent(symbol)
if g is not S.One:
return _invert_real(h, imageset(Lambda(n, n/g), g_ys), symbol)
if f.is_Pow:
base, expo = f.args
base_has_sym = base.has(symbol)
expo_has_sym = expo.has(symbol)
if not expo_has_sym:
if expo.is_rational:
num, den = expo.as_numer_denom()
if den % 2 == 0 and num % 2 == 1 and den.is_zero is False:
root = Lambda(n, real_root(n, expo))
g_ys_pos = g_ys & Interval(0, oo)
res = imageset(root, g_ys_pos)
base_positive = solveset(base >= 0, symbol, S.Reals)
_inv, _set = _invert_real(base, res, symbol)
return (_inv, _set.intersect(base_positive))
if den % 2 == 1:
root = Lambda(n, real_root(n, expo))
res = imageset(root, g_ys)
if num % 2 == 0:
neg_res = imageset(Lambda(n, -n), res)
return _invert_real(base, res + neg_res, symbol)
if num % 2 == 1:
return _invert_real(base, res, symbol)
elif expo.is_irrational:
root = Lambda(n, real_root(n, expo))
g_ys_pos = g_ys & Interval(0, oo)
res = imageset(root, g_ys_pos)
return _invert_real(base, res, symbol)
else:
# indeterminate exponent, e.g. Float or parity of
# num, den of rational could not be determined
pass # use default return
if not base_has_sym:
rhs = g_ys.args[0]
if base.is_positive:
return _invert_real(expo,
imageset(Lambda(n, log(n, base, evaluate=False)), g_ys), symbol)
elif base.is_negative:
from sympy.core.power import integer_log
s, b = integer_log(rhs, base)
if b:
return _invert_real(expo, FiniteSet(s), symbol)
else:
return _invert_real(expo, S.EmptySet, symbol)
elif base.is_zero:
one = Eq(rhs, 1)
if one == S.true:
# special case: 0**x - 1
return _invert_real(expo, FiniteSet(0), symbol)
elif one == S.false:
return _invert_real(expo, S.EmptySet, symbol)
if isinstance(f, TrigonometricFunction):
if isinstance(g_ys, FiniteSet):
def inv(trig):
if isinstance(f, (sin, csc)):
F = asin if isinstance(f, sin) else acsc
return (lambda a: n*pi + (-1)**n*F(a),)
if isinstance(f, (cos, sec)):
F = acos if isinstance(f, cos) else asec
return (
lambda a: 2*n*pi + F(a),
lambda a: 2*n*pi - F(a),)
if isinstance(f, (tan, cot)):
return (lambda a: n*pi + f.inverse()(a),)
n = Dummy('n', integer=True)
invs = S.EmptySet
for L in inv(f):
invs += Union(*[imageset(Lambda(n, L(g)), S.Integers) for g in g_ys])
return _invert_real(f.args[0], invs, symbol)
return (f, g_ys)
def _invert_complex(f, g_ys, symbol):
"""Helper function for _invert."""
if f == symbol:
return (f, g_ys)
n = Dummy('n')
if f.is_Add:
# f = g + h
g, h = f.as_independent(symbol)
if g is not S.Zero:
return _invert_complex(h, imageset(Lambda(n, n - g), g_ys), symbol)
if f.is_Mul:
# f = g*h
g, h = f.as_independent(symbol)
if g is not S.One:
if g in {S.NegativeInfinity, S.ComplexInfinity, S.Infinity}:
return (h, S.EmptySet)
return _invert_complex(h, imageset(Lambda(n, n/g), g_ys), symbol)
if f.is_Pow:
base, expo = f.args
# special case: g**r = 0
# Could be improved like `_invert_real` to handle more general cases.
if expo.is_Rational and g_ys == FiniteSet(0):
if expo.is_positive:
return _invert_complex(base, g_ys, symbol)
if hasattr(f, 'inverse') and f.inverse() is not None and \
not isinstance(f, TrigonometricFunction) and \
not isinstance(f, HyperbolicFunction) and \
not isinstance(f, exp):
if len(f.args) > 1:
raise ValueError("Only functions with one argument are supported.")
return _invert_complex(f.args[0],
imageset(Lambda(n, f.inverse()(n)), g_ys), symbol)
if isinstance(f, exp) or (f.is_Pow and f.base == S.Exp1):
if isinstance(g_ys, ImageSet):
# can solve upto `(d*exp(exp(...(exp(a*x + b))...) + c)` format.
# Further can be improved to `(d*exp(exp(...(exp(a*x**n + b*x**(n-1) + ... + f))...) + c)`.
g_ys_expr = g_ys.lamda.expr
g_ys_vars = g_ys.lamda.variables
k = Dummy('k{}'.format(len(g_ys_vars)))
g_ys_vars_1 = (k,) + g_ys_vars
exp_invs = Union(*[imageset(Lambda((g_ys_vars_1,), (I*(2*k*pi + arg(g_ys_expr))
+ log(Abs(g_ys_expr)))), S.Integers**(len(g_ys_vars_1)))])
elif isinstance(g_ys, FiniteSet):
exp_invs = Union(*[imageset(Lambda(n, I*(2*n*pi + arg(g_y)) +
log(Abs(g_y))), S.Integers)
for g_y in g_ys if g_y != 0])
return _invert_complex(f.exp, exp_invs, symbol)
return (f, g_ys)
def _invert_abs(f, g_ys, symbol):
"""Helper function for inverting absolute value functions.
Returns the complete result of inverting an absolute value
function along with the conditions which must also be satisfied.
If it is certain that all these conditions are met, a `FiniteSet`
of all possible solutions is returned. If any condition cannot be
satisfied, an `EmptySet` is returned. Otherwise, a `ConditionSet`
of the solutions, with all the required conditions specified, is
returned.
"""
if not g_ys.is_FiniteSet:
# this could be used for FiniteSet, but the
# results are more compact if they aren't, e.g.
# ConditionSet(x, Contains(n, Interval(0, oo)), {-n, n}) vs
# Union(Intersection(Interval(0, oo), {n}), Intersection(Interval(-oo, 0), {-n}))
# for the solution of abs(x) - n
pos = Intersection(g_ys, Interval(0, S.Infinity))
parg = _invert_real(f, pos, symbol)
narg = _invert_real(-f, pos, symbol)
if parg[0] != narg[0]:
raise NotImplementedError
return parg[0], Union(narg[1], parg[1])
# check conditions: all these must be true. If any are unknown
# then return them as conditions which must be satisfied
unknown = []
for a in g_ys.args:
ok = a.is_nonnegative if a.is_Number else a.is_positive
if ok is None:
unknown.append(a)
elif not ok:
return symbol, S.EmptySet
if unknown:
conditions = And(*[Contains(i, Interval(0, oo))
for i in unknown])
else:
conditions = True
n = Dummy('n', real=True)
# this is slightly different than above: instead of solving
# +/-f on positive values, here we solve for f on +/- g_ys
g_x, values = _invert_real(f, Union(
imageset(Lambda(n, n), g_ys),
imageset(Lambda(n, -n), g_ys)), symbol)
return g_x, ConditionSet(g_x, conditions, values)
def domain_check(f, symbol, p):
"""Returns False if point p is infinite or any subexpression of f
is infinite or becomes so after replacing symbol with p. If none of
these conditions is met then True will be returned.
Examples
========
>>> from sympy import Mul, oo
>>> from sympy.abc import x
>>> from sympy.solvers.solveset import domain_check
>>> g = 1/(1 + (1/(x + 1))**2)
>>> domain_check(g, x, -1)
False
>>> domain_check(x**2, x, 0)
True
>>> domain_check(1/x, x, oo)
False
* The function relies on the assumption that the original form
of the equation has not been changed by automatic simplification.
>>> domain_check(x/x, x, 0) # x/x is automatically simplified to 1
True
* To deal with automatic evaluations use evaluate=False:
>>> domain_check(Mul(x, 1/x, evaluate=False), x, 0)
False
"""
f, p = sympify(f), sympify(p)
if p.is_infinite:
return False
return _domain_check(f, symbol, p)
def _domain_check(f, symbol, p):
# helper for domain check
if f.is_Atom and f.is_finite:
return True
elif f.subs(symbol, p).is_infinite:
return False
elif isinstance(f, Piecewise):
# Check the cases of the Piecewise in turn. There might be invalid
# expressions in later cases that don't apply e.g.
# solveset(Piecewise((0, Eq(x, 0)), (1/x, True)), x)
for expr, cond in f.args:
condsubs = cond.subs(symbol, p)
if condsubs is S.false:
continue
elif condsubs is S.true:
return _domain_check(expr, symbol, p)
else:
# We don't know which case of the Piecewise holds. On this
# basis we cannot decide whether any solution is in or out of
# the domain. Ideally this function would allow returning a
# symbolic condition for the validity of the solution that
# could be handled in the calling code. In the mean time we'll
# give this particular solution the benefit of the doubt and
# let it pass.
return True
else:
# TODO : We should not blindly recurse through all args of arbitrary expressions like this
return all([_domain_check(g, symbol, p)
for g in f.args])
def _is_finite_with_finite_vars(f, domain=S.Complexes):
"""
Return True if the given expression is finite. For symbols that
don't assign a value for `complex` and/or `real`, the domain will
be used to assign a value; symbols that don't assign a value
for `finite` will be made finite. All other assumptions are
left unmodified.
"""
def assumptions(s):
A = s.assumptions0
A.setdefault('finite', A.get('finite', True))
if domain.is_subset(S.Reals):
# if this gets set it will make complex=True, too
A.setdefault('real', True)
else:
# don't change 'real' because being complex implies
# nothing about being real
A.setdefault('complex', True)
return A
reps = {s: Dummy(**assumptions(s)) for s in f.free_symbols}
return f.xreplace(reps).is_finite
def _is_function_class_equation(func_class, f, symbol):
""" Tests whether the equation is an equation of the given function class.
The given equation belongs to the given function class if it is
comprised of functions of the function class which are multiplied by
or added to expressions independent of the symbol. In addition, the
arguments of all such functions must be linear in the symbol as well.
Examples
========
>>> from sympy.solvers.solveset import _is_function_class_equation
>>> from sympy import tan, sin, tanh, sinh, exp
>>> from sympy.abc import x
>>> from sympy.functions.elementary.trigonometric import (TrigonometricFunction,
... HyperbolicFunction)
>>> _is_function_class_equation(TrigonometricFunction, exp(x) + tan(x), x)
False
>>> _is_function_class_equation(TrigonometricFunction, tan(x) + sin(x), x)
True
>>> _is_function_class_equation(TrigonometricFunction, tan(x**2), x)
False
>>> _is_function_class_equation(TrigonometricFunction, tan(x + 2), x)
True
>>> _is_function_class_equation(HyperbolicFunction, tanh(x) + sinh(x), x)
True
"""
if f.is_Mul or f.is_Add:
return all(_is_function_class_equation(func_class, arg, symbol)
for arg in f.args)
if f.is_Pow:
if not f.exp.has(symbol):
return _is_function_class_equation(func_class, f.base, symbol)
else:
return False
if not f.has(symbol):
return True
if isinstance(f, func_class):
try:
g = Poly(f.args[0], symbol)
return g.degree() <= 1
except PolynomialError:
return False
else:
return False
def _solve_as_rational(f, symbol, domain):
""" solve rational functions"""
from sympy.core.function import _mexpand
f = together(_mexpand(f, recursive=True), deep=True)
g, h = fraction(f)
if not h.has(symbol):
try:
return _solve_as_poly(g, symbol, domain)
except NotImplementedError:
# The polynomial formed from g could end up having
# coefficients in a ring over which finding roots
# isn't implemented yet, e.g. ZZ[a] for some symbol a
return ConditionSet(symbol, Eq(f, 0), domain)
except CoercionFailed:
# contained oo, zoo or nan
return S.EmptySet
else:
valid_solns = _solveset(g, symbol, domain)
invalid_solns = _solveset(h, symbol, domain)
return valid_solns - invalid_solns
class _SolveTrig1Error(Exception):
"""Raised when _solve_trig1 heuristics do not apply"""
def _solve_trig(f, symbol, domain):
"""Function to call other helpers to solve trigonometric equations """
sol = None
try:
sol = _solve_trig1(f, symbol, domain)
except _SolveTrig1Error:
try:
sol = _solve_trig2(f, symbol, domain)
except ValueError:
raise NotImplementedError(filldedent('''
Solution to this kind of trigonometric equations
is yet to be implemented'''))
return sol
def _solve_trig1(f, symbol, domain):
"""Primary solver for trigonometric and hyperbolic equations
Returns either the solution set as a ConditionSet (auto-evaluated to a
union of ImageSets if no variables besides 'symbol' are involved) or
raises _SolveTrig1Error if f == 0 can't be solved.
Notes
=====
Algorithm:
1. Do a change of variable x -> mu*x in arguments to trigonometric and
hyperbolic functions, in order to reduce them to small integers. (This
step is crucial to keep the degrees of the polynomials of step 4 low.)
2. Rewrite trigonometric/hyperbolic functions as exponentials.
3. Proceed to a 2nd change of variable, replacing exp(I*x) or exp(x) by y.
4. Solve the resulting rational equation.
5. Use invert_complex or invert_real to return to the original variable.
6. If the coefficients of 'symbol' were symbolic in nature, add the
necessary consistency conditions in a ConditionSet.
"""
# Prepare change of variable
x = Dummy('x')
if _is_function_class_equation(HyperbolicFunction, f, symbol):
cov = exp(x)
inverter = invert_real if domain.is_subset(S.Reals) else invert_complex
else:
cov = exp(I*x)
inverter = invert_complex
f = trigsimp(f)
f_original = f
trig_functions = f.atoms(TrigonometricFunction, HyperbolicFunction)
trig_arguments = [e.args[0] for e in trig_functions]
# trigsimp may have reduced the equation to an expression
# that is independent of 'symbol' (e.g. cos**2+sin**2)
if not any(a.has(symbol) for a in trig_arguments):
return solveset(f_original, symbol, domain)
denominators = []
numerators = []
for ar in trig_arguments:
try:
poly_ar = Poly(ar, symbol)
except PolynomialError:
raise _SolveTrig1Error("trig argument is not a polynomial")
if poly_ar.degree() > 1: # degree >1 still bad
raise _SolveTrig1Error("degree of variable must not exceed one")
if poly_ar.degree() == 0: # degree 0, don't care
continue
c = poly_ar.all_coeffs()[0] # got the coefficient of 'symbol'
numerators.append(fraction(c)[0])
denominators.append(fraction(c)[1])
mu = lcm(denominators)/gcd(numerators)
f = f.subs(symbol, mu*x)
f = f.rewrite(exp)
f = together(f)
g, h = fraction(f)
y = Dummy('y')
g, h = g.expand(), h.expand()
g, h = g.subs(cov, y), h.subs(cov, y)
if g.has(x) or h.has(x):
raise _SolveTrig1Error("change of variable not possible")
solns = solveset_complex(g, y) - solveset_complex(h, y)
if isinstance(solns, ConditionSet):
raise _SolveTrig1Error("polynomial has ConditionSet solution")
if isinstance(solns, FiniteSet):
if any(isinstance(s, RootOf) for s in solns):
raise _SolveTrig1Error("polynomial results in RootOf object")
# revert the change of variable
cov = cov.subs(x, symbol/mu)
result = Union(*[inverter(cov, s, symbol)[1] for s in solns])
# In case of symbolic coefficients, the solution set is only valid
# if numerator and denominator of mu are non-zero.
if mu.has(Symbol):
syms = (mu).atoms(Symbol)
munum, muden = fraction(mu)
condnum = munum.as_independent(*syms, as_Add=False)[1]
condden = muden.as_independent(*syms, as_Add=False)[1]
cond = And(Ne(condnum, 0), Ne(condden, 0))
else:
cond = True
# Actual conditions are returned as part of the ConditionSet. Adding an
# intersection with C would only complicate some solution sets due to
# current limitations of intersection code. (e.g. #19154)
if domain is S.Complexes:
# This is a slight abuse of ConditionSet. Ideally this should
# be some kind of "PiecewiseSet". (See #19507 discussion)
return ConditionSet(symbol, cond, result)
else:
return ConditionSet(symbol, cond, Intersection(result, domain))
elif solns is S.EmptySet:
return S.EmptySet
else:
raise _SolveTrig1Error("polynomial solutions must form FiniteSet")
def _solve_trig2(f, symbol, domain):
"""Secondary helper to solve trigonometric equations,
called when first helper fails """
from sympy import ilcm, expand_trig, degree
f = trigsimp(f)
f_original = f
trig_functions = f.atoms(sin, cos, tan, sec, cot, csc)
trig_arguments = [e.args[0] for e in trig_functions]
denominators = []
numerators = []
# todo: This solver can be extended to hyperbolics if the
# analogous change of variable to tanh (instead of tan)
# is used.
if not trig_functions:
return ConditionSet(symbol, Eq(f_original, 0), domain)
# todo: The pre-processing below (extraction of numerators, denominators,
# gcd, lcm, mu, etc.) should be updated to the enhanced version in
# _solve_trig1. (See #19507)
for ar in trig_arguments:
try:
poly_ar = Poly(ar, symbol)
except PolynomialError:
raise ValueError("give up, we can't solve if this is not a polynomial in x")
if poly_ar.degree() > 1: # degree >1 still bad
raise ValueError("degree of variable inside polynomial should not exceed one")
if poly_ar.degree() == 0: # degree 0, don't care
continue
c = poly_ar.all_coeffs()[0] # got the coefficient of 'symbol'
try:
numerators.append(Rational(c).p)
denominators.append(Rational(c).q)
except TypeError:
return ConditionSet(symbol, Eq(f_original, 0), domain)
x = Dummy('x')
# ilcm() and igcd() require more than one argument
if len(numerators) > 1:
mu = Rational(2)*ilcm(*denominators)/igcd(*numerators)
else:
assert len(numerators) == 1
mu = Rational(2)*denominators[0]/numerators[0]
f = f.subs(symbol, mu*x)
f = f.rewrite(tan)
f = expand_trig(f)
f = together(f)
g, h = fraction(f)
y = Dummy('y')
g, h = g.expand(), h.expand()
g, h = g.subs(tan(x), y), h.subs(tan(x), y)
if g.has(x) or h.has(x):
return ConditionSet(symbol, Eq(f_original, 0), domain)
solns = solveset(g, y, S.Reals) - solveset(h, y, S.Reals)
if isinstance(solns, FiniteSet):
result = Union(*[invert_real(tan(symbol/mu), s, symbol)[1]
for s in solns])
dsol = invert_real(tan(symbol/mu), oo, symbol)[1]
if degree(h) > degree(g): # If degree(denom)>degree(num) then there
result = Union(result, dsol) # would be another sol at Lim(denom-->oo)
return Intersection(result, domain)
elif solns is S.EmptySet:
return S.EmptySet
else:
return ConditionSet(symbol, Eq(f_original, 0), S.Reals)
def _solve_as_poly(f, symbol, domain=S.Complexes):
"""
Solve the equation using polynomial techniques if it already is a
polynomial equation or, with a change of variables, can be made so.
"""
result = None
if f.is_polynomial(symbol):
solns = roots(f, symbol, cubics=True, quartics=True,
quintics=True, domain='EX')
num_roots = sum(solns.values())
if degree(f, symbol) <= num_roots:
result = FiniteSet(*solns.keys())
else:
poly = Poly(f, symbol)
solns = poly.all_roots()
if poly.degree() <= len(solns):
result = FiniteSet(*solns)
else:
result = ConditionSet(symbol, Eq(f, 0), domain)
else:
poly = Poly(f)
if poly is None:
result = ConditionSet(symbol, Eq(f, 0), domain)
gens = [g for g in poly.gens if g.has(symbol)]
if len(gens) == 1:
poly = Poly(poly, gens[0])
gen = poly.gen
deg = poly.degree()
poly = Poly(poly.as_expr(), poly.gen, composite=True)
poly_solns = FiniteSet(*roots(poly, cubics=True, quartics=True,
quintics=True).keys())
if len(poly_solns) < deg:
result = ConditionSet(symbol, Eq(f, 0), domain)
if gen != symbol:
y = Dummy('y')
inverter = invert_real if domain.is_subset(S.Reals) else invert_complex
lhs, rhs_s = inverter(gen, y, symbol)
if lhs == symbol:
result = Union(*[rhs_s.subs(y, s) for s in poly_solns])
else:
result = ConditionSet(symbol, Eq(f, 0), domain)
else:
result = ConditionSet(symbol, Eq(f, 0), domain)
if result is not None:
if isinstance(result, FiniteSet):
# this is to simplify solutions like -sqrt(-I) to sqrt(2)/2
# - sqrt(2)*I/2. We are not expanding for solution with symbols
# or undefined functions because that makes the solution more complicated.
# For example, expand_complex(a) returns re(a) + I*im(a)
if all([s.atoms(Symbol, AppliedUndef) == set() and not isinstance(s, RootOf)
for s in result]):
s = Dummy('s')
result = imageset(Lambda(s, expand_complex(s)), result)
if isinstance(result, FiniteSet) and domain != S.Complexes:
# Avoid adding gratuitous intersections with S.Complexes. Actual
# conditions should be handled elsewhere.
result = result.intersection(domain)
return result
else:
return ConditionSet(symbol, Eq(f, 0), domain)
def _solve_radical(f, unradf, symbol, solveset_solver):
""" Helper function to solve equations with radicals """
res = unradf
eq, cov = res if res else (f, [])
if not cov:
result = solveset_solver(eq, symbol) - \
Union(*[solveset_solver(g, symbol) for g in denoms(f, symbol)])
else:
y, yeq = cov
if not solveset_solver(y - I, y):
yreal = Dummy('yreal', real=True)
yeq = yeq.xreplace({y: yreal})
eq = eq.xreplace({y: yreal})
y = yreal
g_y_s = solveset_solver(yeq, symbol)
f_y_sols = solveset_solver(eq, y)
result = Union(*[imageset(Lambda(y, g_y), f_y_sols)
for g_y in g_y_s])
if isinstance(result, Complement) or isinstance(result,ConditionSet):
solution_set = result
else:
f_set = [] # solutions for FiniteSet
c_set = [] # solutions for ConditionSet
for s in result:
if checksol(f, symbol, s):
f_set.append(s)
else:
c_set.append(s)
solution_set = FiniteSet(*f_set) + ConditionSet(symbol, Eq(f, 0), FiniteSet(*c_set))
return solution_set
def _solve_abs(f, symbol, domain):
""" Helper function to solve equation involving absolute value function """
if not domain.is_subset(S.Reals):
raise ValueError(filldedent('''
Absolute values cannot be inverted in the
complex domain.'''))
p, q, r = Wild('p'), Wild('q'), Wild('r')
pattern_match = f.match(p*Abs(q) + r) or {}
f_p, f_q, f_r = [pattern_match.get(i, S.Zero) for i in (p, q, r)]
if not (f_p.is_zero or f_q.is_zero):
domain = continuous_domain(f_q, symbol, domain)
q_pos_cond = solve_univariate_inequality(f_q >= 0, symbol,
relational=False, domain=domain, continuous=True)
q_neg_cond = q_pos_cond.complement(domain)
sols_q_pos = solveset_real(f_p*f_q + f_r,
symbol).intersect(q_pos_cond)
sols_q_neg = solveset_real(f_p*(-f_q) + f_r,
symbol).intersect(q_neg_cond)
return Union(sols_q_pos, sols_q_neg)
else:
return ConditionSet(symbol, Eq(f, 0), domain)
def solve_decomposition(f, symbol, domain):
"""
Function to solve equations via the principle of "Decomposition
and Rewriting".
Examples
========
>>> from sympy import exp, sin, Symbol, pprint, S
>>> from sympy.solvers.solveset import solve_decomposition as sd
>>> x = Symbol('x')
>>> f1 = exp(2*x) - 3*exp(x) + 2
>>> sd(f1, x, S.Reals)
FiniteSet(0, log(2))
>>> f2 = sin(x)**2 + 2*sin(x) + 1
>>> pprint(sd(f2, x, S.Reals), use_unicode=False)
3*pi
{2*n*pi + ---- | n in Integers}
2
>>> f3 = sin(x + 2)
>>> pprint(sd(f3, x, S.Reals), use_unicode=False)
{2*n*pi - 2 | n in Integers} U {2*n*pi - 2 + pi | n in Integers}
"""
from sympy.solvers.decompogen import decompogen
from sympy.calculus.util import function_range
# decompose the given function
g_s = decompogen(f, symbol)
# `y_s` represents the set of values for which the function `g` is to be
# solved.
# `solutions` represent the solutions of the equations `g = y_s` or
# `g = 0` depending on the type of `y_s`.
# As we are interested in solving the equation: f = 0
y_s = FiniteSet(0)
for g in g_s:
frange = function_range(g, symbol, domain)
y_s = Intersection(frange, y_s)
result = S.EmptySet
if isinstance(y_s, FiniteSet):
for y in y_s:
solutions = solveset(Eq(g, y), symbol, domain)
if not isinstance(solutions, ConditionSet):
result += solutions
else:
if isinstance(y_s, ImageSet):
iter_iset = (y_s,)
elif isinstance(y_s, Union):
iter_iset = y_s.args
elif y_s is EmptySet:
# y_s is not in the range of g in g_s, so no solution exists
#in the given domain
return EmptySet
for iset in iter_iset:
new_solutions = solveset(Eq(iset.lamda.expr, g), symbol, domain)
dummy_var = tuple(iset.lamda.expr.free_symbols)[0]
(base_set,) = iset.base_sets
if isinstance(new_solutions, FiniteSet):
new_exprs = new_solutions
elif isinstance(new_solutions, Intersection):
if isinstance(new_solutions.args[1], FiniteSet):
new_exprs = new_solutions.args[1]
for new_expr in new_exprs:
result += ImageSet(Lambda(dummy_var, new_expr), base_set)
if result is S.EmptySet:
return ConditionSet(symbol, Eq(f, 0), domain)
y_s = result
return y_s
def _solveset(f, symbol, domain, _check=False):
"""Helper for solveset to return a result from an expression
that has already been sympify'ed and is known to contain the
given symbol."""
# _check controls whether the answer is checked or not
from sympy.simplify.simplify import signsimp
from sympy.logic.boolalg import BooleanTrue
if isinstance(f, BooleanTrue):
return domain
orig_f = f
if f.is_Mul:
coeff, f = f.as_independent(symbol, as_Add=False)
if coeff in {S.ComplexInfinity, S.NegativeInfinity, S.Infinity}:
f = together(orig_f)
elif f.is_Add:
a, h = f.as_independent(symbol)
m, h = h.as_independent(symbol, as_Add=False)
if m not in {S.ComplexInfinity, S.Zero, S.Infinity,
S.NegativeInfinity}:
f = a/m + h # XXX condition `m != 0` should be added to soln
# assign the solvers to use
solver = lambda f, x, domain=domain: _solveset(f, x, domain)
inverter = lambda f, rhs, symbol: _invert(f, rhs, symbol, domain)
result = EmptySet
if f.expand().is_zero:
return domain
elif not f.has(symbol):
return EmptySet
elif f.is_Mul and all(_is_finite_with_finite_vars(m, domain)
for m in f.args):
# if f(x) and g(x) are both finite we can say that the solution of
# f(x)*g(x) == 0 is same as Union(f(x) == 0, g(x) == 0) is not true in
# general. g(x) can grow to infinitely large for the values where
# f(x) == 0. To be sure that we are not silently allowing any
# wrong solutions we are using this technique only if both f and g are
# finite for a finite input.
result = Union(*[solver(m, symbol) for m in f.args])
elif _is_function_class_equation(TrigonometricFunction, f, symbol) or \
_is_function_class_equation(HyperbolicFunction, f, symbol):
result = _solve_trig(f, symbol, domain)
elif isinstance(f, arg):
a = f.args[0]
result = solveset_real(a > 0, symbol)
elif f.is_Piecewise:
expr_set_pairs = f.as_expr_set_pairs(domain)
for (expr, in_set) in expr_set_pairs:
if in_set.is_Relational:
in_set = in_set.as_set()
solns = solver(expr, symbol, in_set)
result += solns
elif isinstance(f, Eq):
result = solver(Add(f.lhs, - f.rhs, evaluate=False), symbol, domain)
elif f.is_Relational:
try:
result = solve_univariate_inequality(
f, symbol, domain=domain, relational=False)
except NotImplementedError:
result = ConditionSet(symbol, f, domain)
return result
elif _is_modular(f, symbol):
result = _solve_modular(f, symbol, domain)
else:
lhs, rhs_s = inverter(f, 0, symbol)
if lhs == symbol:
# do some very minimal simplification since
# repeated inversion may have left the result
# in a state that other solvers (e.g. poly)
# would have simplified; this is done here
# rather than in the inverter since here it
# is only done once whereas there it would
# be repeated for each step of the inversion
if isinstance(rhs_s, FiniteSet):
rhs_s = FiniteSet(*[Mul(*
signsimp(i).as_content_primitive())
for i in rhs_s])
result = rhs_s
elif isinstance(rhs_s, FiniteSet):
for equation in [lhs - rhs for rhs in rhs_s]:
if equation == f:
u = unrad(f)
if u:
result += _solve_radical(equation, u,
symbol,
solver)
elif equation.has(Abs):
result += _solve_abs(f, symbol, domain)
else:
result_rational = _solve_as_rational(equation, symbol, domain)
if not isinstance(result_rational, ConditionSet):
result += result_rational
else:
# may be a transcendental type equation
t_result = _transolve(equation, symbol, domain)
if isinstance(t_result, ConditionSet):
# might need factoring; this is expensive so we
# have delayed until now. To avoid recursion
# errors look for a non-trivial factoring into
# a product of symbol dependent terms; I think
# that something that factors as a Pow would
# have already been recognized by now.
factored = equation.factor()
if factored.is_Mul and equation != factored:
_, dep = factored.as_independent(symbol)
if not dep.is_Add:
# non-trivial factoring of equation
# but use form with constants
# in case they need special handling
t_result = solver(factored, symbol)
result += t_result
else:
result += solver(equation, symbol)
elif rhs_s is not S.EmptySet:
result = ConditionSet(symbol, Eq(f, 0), domain)
if isinstance(result, ConditionSet):
if isinstance(f, Expr):
num, den = f.as_numer_denom()
else:
num, den = f, S.One
if den.has(symbol):
_result = _solveset(num, symbol, domain)
if not isinstance(_result, ConditionSet):
singularities = _solveset(den, symbol, domain)
result = _result - singularities
if _check:
if isinstance(result, ConditionSet):
# it wasn't solved or has enumerated all conditions
# -- leave it alone
return result
# whittle away all but the symbol-containing core
# to use this for testing
if isinstance(orig_f, Expr):
fx = orig_f.as_independent(symbol, as_Add=True)[1]
fx = fx.as_independent(symbol, as_Add=False)[1]
else:
fx = orig_f
if isinstance(result, FiniteSet):
# check the result for invalid solutions
result = FiniteSet(*[s for s in result
if isinstance(s, RootOf)
or domain_check(fx, symbol, s)])
return result
def _is_modular(f, symbol):
"""
Helper function to check below mentioned types of modular equations.
``A - Mod(B, C) = 0``
A -> This can or cannot be a function of symbol.
B -> This is surely a function of symbol.
C -> It is an integer.
Parameters
==========
f : Expr
The equation to be checked.
symbol : Symbol
The concerned variable for which the equation is to be checked.
Examples
========
>>> from sympy import symbols, exp, Mod
>>> from sympy.solvers.solveset import _is_modular as check
>>> x, y = symbols('x y')
>>> check(Mod(x, 3) - 1, x)
True
>>> check(Mod(x, 3) - 1, y)
False
>>> check(Mod(x, 3)**2 - 5, x)
False
>>> check(Mod(x, 3)**2 - y, x)
False
>>> check(exp(Mod(x, 3)) - 1, x)
False
>>> check(Mod(3, y) - 1, y)
False
"""
if not f.has(Mod):
return False
# extract modterms from f.
modterms = list(f.atoms(Mod))
return (len(modterms) == 1 and # only one Mod should be present
modterms[0].args[0].has(symbol) and # B-> function of symbol
modterms[0].args[1].is_integer and # C-> to be an integer.
any(isinstance(term, Mod)
for term in list(_term_factors(f))) # free from other funcs
)
def _invert_modular(modterm, rhs, n, symbol):
"""
Helper function to invert modular equation.
``Mod(a, m) - rhs = 0``
Generally it is inverted as (a, ImageSet(Lambda(n, m*n + rhs), S.Integers)).
More simplified form will be returned if possible.
If it is not invertible then (modterm, rhs) is returned.
The following cases arise while inverting equation ``Mod(a, m) - rhs = 0``:
1. If a is symbol then m*n + rhs is the required solution.
2. If a is an instance of ``Add`` then we try to find two symbol independent
parts of a and the symbol independent part gets tranferred to the other
side and again the ``_invert_modular`` is called on the symbol
dependent part.
3. If a is an instance of ``Mul`` then same as we done in ``Add`` we separate
out the symbol dependent and symbol independent parts and transfer the
symbol independent part to the rhs with the help of invert and again the
``_invert_modular`` is called on the symbol dependent part.
4. If a is an instance of ``Pow`` then two cases arise as following:
- If a is of type (symbol_indep)**(symbol_dep) then the remainder is
evaluated with the help of discrete_log function and then the least
period is being found out with the help of totient function.
period*n + remainder is the required solution in this case.
For reference: (https://en.wikipedia.org/wiki/Euler's_theorem)
- If a is of type (symbol_dep)**(symbol_indep) then we try to find all
primitive solutions list with the help of nthroot_mod function.
m*n + rem is the general solution where rem belongs to solutions list
from nthroot_mod function.
Parameters
==========
modterm, rhs : Expr
The modular equation to be inverted, ``modterm - rhs = 0``
symbol : Symbol
The variable in the equation to be inverted.
n : Dummy
Dummy variable for output g_n.
Returns
=======
A tuple (f_x, g_n) is being returned where f_x is modular independent function
of symbol and g_n being set of values f_x can have.
Examples
========
>>> from sympy import symbols, exp, Mod, Dummy, S
>>> from sympy.solvers.solveset import _invert_modular as invert_modular
>>> x, y = symbols('x y')
>>> n = Dummy('n')
>>> invert_modular(Mod(exp(x), 7), S(5), n, x)
(Mod(exp(x), 7), 5)
>>> invert_modular(Mod(x, 7), S(5), n, x)
(x, ImageSet(Lambda(_n, 7*_n + 5), Integers))
>>> invert_modular(Mod(3*x + 8, 7), S(5), n, x)
(x, ImageSet(Lambda(_n, 7*_n + 6), Integers))
>>> invert_modular(Mod(x**4, 7), S(5), n, x)
(x, EmptySet)
>>> invert_modular(Mod(2**(x**2 + x + 1), 7), S(2), n, x)
(x**2 + x + 1, ImageSet(Lambda(_n, 3*_n + 1), Naturals0))
"""
a, m = modterm.args
if rhs.is_real is False or any(term.is_real is False
for term in list(_term_factors(a))):
# Check for complex arguments
return modterm, rhs
if abs(rhs) >= abs(m):
# if rhs has value greater than value of m.
return symbol, EmptySet
if a == symbol:
return symbol, ImageSet(Lambda(n, m*n + rhs), S.Integers)
if a.is_Add:
# g + h = a
g, h = a.as_independent(symbol)
if g is not S.Zero:
x_indep_term = rhs - Mod(g, m)
return _invert_modular(Mod(h, m), Mod(x_indep_term, m), n, symbol)
if a.is_Mul:
# g*h = a
g, h = a.as_independent(symbol)
if g is not S.One:
x_indep_term = rhs*invert(g, m)
return _invert_modular(Mod(h, m), Mod(x_indep_term, m), n, symbol)
if a.is_Pow:
# base**expo = a
base, expo = a.args
if expo.has(symbol) and not base.has(symbol):
# remainder -> solution independent of n of equation.
# m, rhs are made coprime by dividing igcd(m, rhs)
try:
remainder = discrete_log(m / igcd(m, rhs), rhs, a.base)
except ValueError: # log does not exist
return modterm, rhs
# period -> coefficient of n in the solution and also referred as
# the least period of expo in which it is repeats itself.
# (a**(totient(m)) - 1) divides m. Here is link of theorem:
# (https://en.wikipedia.org/wiki/Euler's_theorem)
period = totient(m)
for p in divisors(period):
# there might a lesser period exist than totient(m).
if pow(a.base, p, m / igcd(m, a.base)) == 1:
period = p
break
# recursion is not applied here since _invert_modular is currently
# not smart enough to handle infinite rhs as here expo has infinite
# rhs = ImageSet(Lambda(n, period*n + remainder), S.Naturals0).
return expo, ImageSet(Lambda(n, period*n + remainder), S.Naturals0)
elif base.has(symbol) and not expo.has(symbol):
try:
remainder_list = nthroot_mod(rhs, expo, m, all_roots=True)
if remainder_list == []:
return symbol, EmptySet
except (ValueError, NotImplementedError):
return modterm, rhs
g_n = EmptySet
for rem in remainder_list:
g_n += ImageSet(Lambda(n, m*n + rem), S.Integers)
return base, g_n
return modterm, rhs
def _solve_modular(f, symbol, domain):
r"""
Helper function for solving modular equations of type ``A - Mod(B, C) = 0``,
where A can or cannot be a function of symbol, B is surely a function of
symbol and C is an integer.
Currently ``_solve_modular`` is only able to solve cases
where A is not a function of symbol.
Parameters
==========
f : Expr
The modular equation to be solved, ``f = 0``
symbol : Symbol
The variable in the equation to be solved.
domain : Set
A set over which the equation is solved. It has to be a subset of
Integers.
Returns
=======
A set of integer solutions satisfying the given modular equation.
A ``ConditionSet`` if the equation is unsolvable.
Examples
========
>>> from sympy.solvers.solveset import _solve_modular as solve_modulo
>>> from sympy import S, Symbol, sin, Intersection, Interval
>>> from sympy.core.mod import Mod
>>> x = Symbol('x')
>>> solve_modulo(Mod(5*x - 8, 7) - 3, x, S.Integers)
ImageSet(Lambda(_n, 7*_n + 5), Integers)
>>> solve_modulo(Mod(5*x - 8, 7) - 3, x, S.Reals) # domain should be subset of integers.
ConditionSet(x, Eq(Mod(5*x + 6, 7) - 3, 0), Reals)
>>> solve_modulo(-7 + Mod(x, 5), x, S.Integers)
EmptySet
>>> solve_modulo(Mod(12**x, 21) - 18, x, S.Integers)
ImageSet(Lambda(_n, 6*_n + 2), Naturals0)
>>> solve_modulo(Mod(sin(x), 7) - 3, x, S.Integers) # not solvable
ConditionSet(x, Eq(Mod(sin(x), 7) - 3, 0), Integers)
>>> solve_modulo(3 - Mod(x, 5), x, Intersection(S.Integers, Interval(0, 100)))
Intersection(ImageSet(Lambda(_n, 5*_n + 3), Integers), Range(0, 101, 1))
"""
# extract modterm and g_y from f
unsolved_result = ConditionSet(symbol, Eq(f, 0), domain)
modterm = list(f.atoms(Mod))[0]
rhs = -S.One*(f.subs(modterm, S.Zero))
if f.as_coefficients_dict()[modterm].is_negative:
# checks if coefficient of modterm is negative in main equation.
rhs *= -S.One
if not domain.is_subset(S.Integers):
return unsolved_result
if rhs.has(symbol):
# TODO Case: A-> function of symbol, can be extended here
# in future.
return unsolved_result
n = Dummy('n', integer=True)
f_x, g_n = _invert_modular(modterm, rhs, n, symbol)
if f_x == modterm and g_n == rhs:
return unsolved_result
if f_x == symbol:
if domain is not S.Integers:
return domain.intersect(g_n)
return g_n
if isinstance(g_n, ImageSet):
lamda_expr = g_n.lamda.expr
lamda_vars = g_n.lamda.variables
base_sets = g_n.base_sets
sol_set = _solveset(f_x - lamda_expr, symbol, S.Integers)
if isinstance(sol_set, FiniteSet):
tmp_sol = EmptySet
for sol in sol_set:
tmp_sol += ImageSet(Lambda(lamda_vars, sol), *base_sets)
sol_set = tmp_sol
else:
sol_set = ImageSet(Lambda(lamda_vars, sol_set), *base_sets)
return domain.intersect(sol_set)
return unsolved_result
def _term_factors(f):
"""
Iterator to get the factors of all terms present
in the given equation.
Parameters
==========
f : Expr
Equation that needs to be addressed
Returns
=======
Factors of all terms present in the equation.
Examples
========
>>> from sympy import symbols
>>> from sympy.solvers.solveset import _term_factors
>>> x = symbols('x')
>>> list(_term_factors(-2 - x**2 + x*(x + 1)))
[-2, -1, x**2, x, x + 1]
"""
for add_arg in Add.make_args(f):
yield from Mul.make_args(add_arg)
def _solve_exponential(lhs, rhs, symbol, domain):
r"""
Helper function for solving (supported) exponential equations.
Exponential equations are the sum of (currently) at most
two terms with one or both of them having a power with a
symbol-dependent exponent.
For example
.. math:: 5^{2x + 3} - 5^{3x - 1}
.. math:: 4^{5 - 9x} - e^{2 - x}
Parameters
==========
lhs, rhs : Expr
The exponential equation to be solved, `lhs = rhs`
symbol : Symbol
The variable in which the equation is solved
domain : Set
A set over which the equation is solved.
Returns
=======
A set of solutions satisfying the given equation.
A ``ConditionSet`` if the equation is unsolvable or
if the assumptions are not properly defined, in that case
a different style of ``ConditionSet`` is returned having the
solution(s) of the equation with the desired assumptions.
Examples
========
>>> from sympy.solvers.solveset import _solve_exponential as solve_expo
>>> from sympy import symbols, S
>>> x = symbols('x', real=True)
>>> a, b = symbols('a b')
>>> solve_expo(2**x + 3**x - 5**x, 0, x, S.Reals) # not solvable
ConditionSet(x, Eq(2**x + 3**x - 5**x, 0), Reals)
>>> solve_expo(a**x - b**x, 0, x, S.Reals) # solvable but incorrect assumptions
ConditionSet(x, (a > 0) & (b > 0), FiniteSet(0))
>>> solve_expo(3**(2*x) - 2**(x + 3), 0, x, S.Reals)
FiniteSet(-3*log(2)/(-2*log(3) + log(2)))
>>> solve_expo(2**x - 4**x, 0, x, S.Reals)
FiniteSet(0)
* Proof of correctness of the method
The logarithm function is the inverse of the exponential function.
The defining relation between exponentiation and logarithm is:
.. math:: {\log_b x} = y \enspace if \enspace b^y = x
Therefore if we are given an equation with exponent terms, we can
convert every term to its corresponding logarithmic form. This is
achieved by taking logarithms and expanding the equation using
logarithmic identities so that it can easily be handled by ``solveset``.
For example:
.. math:: 3^{2x} = 2^{x + 3}
Taking log both sides will reduce the equation to
.. math:: (2x)\log(3) = (x + 3)\log(2)
This form can be easily handed by ``solveset``.
"""
unsolved_result = ConditionSet(symbol, Eq(lhs - rhs, 0), domain)
newlhs = powdenest(lhs)
if lhs != newlhs:
# it may also be advantageous to factor the new expr
neweq = factor(newlhs - rhs)
if neweq != (lhs - rhs):
return _solveset(neweq, symbol, domain) # try again with _solveset
if not (isinstance(lhs, Add) and len(lhs.args) == 2):
# solving for the sum of more than two powers is possible
# but not yet implemented
return unsolved_result
if rhs != 0:
return unsolved_result
a, b = list(ordered(lhs.args))
a_term = a.as_independent(symbol)[1]
b_term = b.as_independent(symbol)[1]
a_base, a_exp = a_term.as_base_exp()
b_base, b_exp = b_term.as_base_exp()
from sympy.functions.elementary.complexes import im
if domain.is_subset(S.Reals):
conditions = And(
a_base > 0,
b_base > 0,
Eq(im(a_exp), 0),
Eq(im(b_exp), 0))
else:
conditions = And(
Ne(a_base, 0),
Ne(b_base, 0))
L, R = map(lambda i: expand_log(log(i), force=True), (a, -b))
solutions = _solveset(L - R, symbol, domain)
return ConditionSet(symbol, conditions, solutions)
def _is_exponential(f, symbol):
r"""
Return ``True`` if one or more terms contain ``symbol`` only in
exponents, else ``False``.
Parameters
==========
f : Expr
The equation to be checked
symbol : Symbol
The variable in which the equation is checked
Examples
========
>>> from sympy import symbols, cos, exp
>>> from sympy.solvers.solveset import _is_exponential as check
>>> x, y = symbols('x y')
>>> check(y, y)
False
>>> check(x**y - 1, y)
True
>>> check(x**y*2**y - 1, y)
True
>>> check(exp(x + 3) + 3**x, x)
True
>>> check(cos(2**x), x)
False
* Philosophy behind the helper
The function extracts each term of the equation and checks if it is
of exponential form w.r.t ``symbol``.
"""
rv = False
for expr_arg in _term_factors(f):
if symbol not in expr_arg.free_symbols:
continue
if (isinstance(expr_arg, Pow) and
symbol not in expr_arg.base.free_symbols or
isinstance(expr_arg, exp)):
rv = True # symbol in exponent
else:
return False # dependent on symbol in non-exponential way
return rv
def _solve_logarithm(lhs, rhs, symbol, domain):
r"""
Helper to solve logarithmic equations which are reducible
to a single instance of `\log`.
Logarithmic equations are (currently) the equations that contains
`\log` terms which can be reduced to a single `\log` term or
a constant using various logarithmic identities.
For example:
.. math:: \log(x) + \log(x - 4)
can be reduced to:
.. math:: \log(x(x - 4))
Parameters
==========
lhs, rhs : Expr
The logarithmic equation to be solved, `lhs = rhs`
symbol : Symbol
The variable in which the equation is solved
domain : Set
A set over which the equation is solved.
Returns
=======
A set of solutions satisfying the given equation.
A ``ConditionSet`` if the equation is unsolvable.
Examples
========
>>> from sympy import symbols, log, S
>>> from sympy.solvers.solveset import _solve_logarithm as solve_log
>>> x = symbols('x')
>>> f = log(x - 3) + log(x + 3)
>>> solve_log(f, 0, x, S.Reals)
FiniteSet(sqrt(10), -sqrt(10))
* Proof of correctness
A logarithm is another way to write exponent and is defined by
.. math:: {\log_b x} = y \enspace if \enspace b^y = x
When one side of the equation contains a single logarithm, the
equation can be solved by rewriting the equation as an equivalent
exponential equation as defined above. But if one side contains
more than one logarithm, we need to use the properties of logarithm
to condense it into a single logarithm.
Take for example
.. math:: \log(2x) - 15 = 0
contains single logarithm, therefore we can directly rewrite it to
exponential form as
.. math:: x = \frac{e^{15}}{2}
But if the equation has more than one logarithm as
.. math:: \log(x - 3) + \log(x + 3) = 0
we use logarithmic identities to convert it into a reduced form
Using,
.. math:: \log(a) + \log(b) = \log(ab)
the equation becomes,
.. math:: \log((x - 3)(x + 3))
This equation contains one logarithm and can be solved by rewriting
to exponents.
"""
new_lhs = logcombine(lhs, force=True)
new_f = new_lhs - rhs
return _solveset(new_f, symbol, domain)
def _is_logarithmic(f, symbol):
r"""
Return ``True`` if the equation is in the form
`a\log(f(x)) + b\log(g(x)) + ... + c` else ``False``.
Parameters
==========
f : Expr
The equation to be checked
symbol : Symbol
The variable in which the equation is checked
Returns
=======
``True`` if the equation is logarithmic otherwise ``False``.
Examples
========
>>> from sympy import symbols, tan, log
>>> from sympy.solvers.solveset import _is_logarithmic as check
>>> x, y = symbols('x y')
>>> check(log(x + 2) - log(x + 3), x)
True
>>> check(tan(log(2*x)), x)
False
>>> check(x*log(x), x)
False
>>> check(x + log(x), x)
False
>>> check(y + log(x), x)
True
* Philosophy behind the helper
The function extracts each term and checks whether it is
logarithmic w.r.t ``symbol``.
"""
rv = False
for term in Add.make_args(f):
saw_log = False
for term_arg in Mul.make_args(term):
if symbol not in term_arg.free_symbols:
continue
if isinstance(term_arg, log):
if saw_log:
return False # more than one log in term
saw_log = True
else:
return False # dependent on symbol in non-log way
if saw_log:
rv = True
return rv
def _is_lambert(f, symbol):
r"""
If this returns ``False`` then the Lambert solver (``_solve_lambert``) will not be called.
Explanation
===========
Quick check for cases that the Lambert solver might be able to handle.
1. Equations containing more than two operands and `symbol`s involving any of
`Pow`, `exp`, `HyperbolicFunction`,`TrigonometricFunction`, `log` terms.
2. In `Pow`, `exp` the exponent should have `symbol` whereas for
`HyperbolicFunction`,`TrigonometricFunction`, `log` should contain `symbol`.
3. For `HyperbolicFunction`,`TrigonometricFunction` the number of trigonometric functions in
equation should be less than number of symbols. (since `A*cos(x) + B*sin(x) - c`
is not the Lambert type).
Some forms of lambert equations are:
1. X**X = C
2. X*(B*log(X) + D)**A = C
3. A*log(B*X + A) + d*X = C
4. (B*X + A)*exp(d*X + g) = C
5. g*exp(B*X + h) - B*X = C
6. A*D**(E*X + g) - B*X = C
7. A*cos(X) + B*sin(X) - D*X = C
8. A*cosh(X) + B*sinh(X) - D*X = C
Where X is any variable,
A, B, C, D, E are any constants,
g, h are linear functions or log terms.
Parameters
==========
f : Expr
The equation to be checked
symbol : Symbol
The variable in which the equation is checked
Returns
=======
If this returns ``False`` then the Lambert solver (``_solve_lambert``) will not be called.
Examples
========
>>> from sympy.solvers.solveset import _is_lambert
>>> from sympy import symbols, cosh, sinh, log
>>> x = symbols('x')
>>> _is_lambert(3*log(x) - x*log(3), x)
True
>>> _is_lambert(log(log(x - 3)) + log(x-3), x)
True
>>> _is_lambert(cosh(x) - sinh(x), x)
False
>>> _is_lambert((x**2 - 2*x + 1).subs(x, (log(x) + 3*x)**2 - 1), x)
True
See Also
========
_solve_lambert
"""
term_factors = list(_term_factors(f.expand()))
# total number of symbols in equation
no_of_symbols = len([arg for arg in term_factors if arg.has(symbol)])
# total number of trigonometric terms in equation
no_of_trig = len([arg for arg in term_factors \
if arg.has(HyperbolicFunction, TrigonometricFunction)])
if f.is_Add and no_of_symbols >= 2:
# `log`, `HyperbolicFunction`, `TrigonometricFunction` should have symbols
# and no_of_trig < no_of_symbols
lambert_funcs = (log, HyperbolicFunction, TrigonometricFunction)
if any(isinstance(arg, lambert_funcs)\
for arg in term_factors if arg.has(symbol)):
if no_of_trig < no_of_symbols:
return True
# here, `Pow`, `exp` exponent should have symbols
elif any(isinstance(arg, (Pow, exp)) \
for arg in term_factors if (arg.as_base_exp()[1]).has(symbol)):
return True
return False
def _transolve(f, symbol, domain):
r"""
Function to solve transcendental equations. It is a helper to
``solveset`` and should be used internally. ``_transolve``
currently supports the following class of equations:
- Exponential equations
- Logarithmic equations
Parameters
==========
f : Any transcendental equation that needs to be solved.
This needs to be an expression, which is assumed
to be equal to ``0``.
symbol : The variable for which the equation is solved.
This needs to be of class ``Symbol``.
domain : A set over which the equation is solved.
This needs to be of class ``Set``.
Returns
=======
Set
A set of values for ``symbol`` for which ``f`` is equal to
zero. An ``EmptySet`` is returned if ``f`` does not have solutions
in respective domain. A ``ConditionSet`` is returned as unsolved
object if algorithms to evaluate complete solution are not
yet implemented.
How to use ``_transolve``
=========================
``_transolve`` should not be used as an independent function, because
it assumes that the equation (``f``) and the ``symbol`` comes from
``solveset`` and might have undergone a few modification(s).
To use ``_transolve`` as an independent function the equation (``f``)
and the ``symbol`` should be passed as they would have been by
``solveset``.
Examples
========
>>> from sympy.solvers.solveset import _transolve as transolve
>>> from sympy.solvers.solvers import _tsolve as tsolve
>>> from sympy import symbols, S, pprint
>>> x = symbols('x', real=True) # assumption added
>>> transolve(5**(x - 3) - 3**(2*x + 1), x, S.Reals)
FiniteSet(-(log(3) + 3*log(5))/(-log(5) + 2*log(3)))
How ``_transolve`` works
========================
``_transolve`` uses two types of helper functions to solve equations
of a particular class:
Identifying helpers: To determine whether a given equation
belongs to a certain class of equation or not. Returns either
``True`` or ``False``.
Solving helpers: Once an equation is identified, a corresponding
helper either solves the equation or returns a form of the equation
that ``solveset`` might better be able to handle.
* Philosophy behind the module
The purpose of ``_transolve`` is to take equations which are not
already polynomial in their generator(s) and to either recast them
as such through a valid transformation or to solve them outright.
A pair of helper functions for each class of supported
transcendental functions are employed for this purpose. One
identifies the transcendental form of an equation and the other
either solves it or recasts it into a tractable form that can be
solved by ``solveset``.
For example, an equation in the form `ab^{f(x)} - cd^{g(x)} = 0`
can be transformed to
`\log(a) + f(x)\log(b) - \log(c) - g(x)\log(d) = 0`
(under certain assumptions) and this can be solved with ``solveset``
if `f(x)` and `g(x)` are in polynomial form.
How ``_transolve`` is better than ``_tsolve``
=============================================
1) Better output
``_transolve`` provides expressions in a more simplified form.
Consider a simple exponential equation
>>> f = 3**(2*x) - 2**(x + 3)
>>> pprint(transolve(f, x, S.Reals), use_unicode=False)
-3*log(2)
{------------------}
-2*log(3) + log(2)
>>> pprint(tsolve(f, x), use_unicode=False)
/ 3 \
| --------|
| log(2/9)|
[-log\2 /]
2) Extensible
The API of ``_transolve`` is designed such that it is easily
extensible, i.e. the code that solves a given class of
equations is encapsulated in a helper and not mixed in with
the code of ``_transolve`` itself.
3) Modular
``_transolve`` is designed to be modular i.e, for every class of
equation a separate helper for identification and solving is
implemented. This makes it easy to change or modify any of the
method implemented directly in the helpers without interfering
with the actual structure of the API.
4) Faster Computation
Solving equation via ``_transolve`` is much faster as compared to
``_tsolve``. In ``solve``, attempts are made computing every possibility
to get the solutions. This series of attempts makes solving a bit
slow. In ``_transolve``, computation begins only after a particular
type of equation is identified.
How to add new class of equations
=================================
Adding a new class of equation solver is a three-step procedure:
- Identify the type of the equations
Determine the type of the class of equations to which they belong:
it could be of ``Add``, ``Pow``, etc. types. Separate internal functions
are used for each type. Write identification and solving helpers
and use them from within the routine for the given type of equation
(after adding it, if necessary). Something like:
.. code-block:: python
def add_type(lhs, rhs, x):
....
if _is_exponential(lhs, x):
new_eq = _solve_exponential(lhs, rhs, x)
....
rhs, lhs = eq.as_independent(x)
if lhs.is_Add:
result = add_type(lhs, rhs, x)
- Define the identification helper.
- Define the solving helper.
Apart from this, a few other things needs to be taken care while
adding an equation solver:
- Naming conventions:
Name of the identification helper should be as
``_is_class`` where class will be the name or abbreviation
of the class of equation. The solving helper will be named as
``_solve_class``.
For example: for exponential equations it becomes
``_is_exponential`` and ``_solve_expo``.
- The identifying helpers should take two input parameters,
the equation to be checked and the variable for which a solution
is being sought, while solving helpers would require an additional
domain parameter.
- Be sure to consider corner cases.
- Add tests for each helper.
- Add a docstring to your helper that describes the method
implemented.
The documentation of the helpers should identify:
- the purpose of the helper,
- the method used to identify and solve the equation,
- a proof of correctness
- the return values of the helpers
"""
def add_type(lhs, rhs, symbol, domain):
"""
Helper for ``_transolve`` to handle equations of
``Add`` type, i.e. equations taking the form as
``a*f(x) + b*g(x) + .... = c``.
For example: 4**x + 8**x = 0
"""
result = ConditionSet(symbol, Eq(lhs - rhs, 0), domain)
# check if it is exponential type equation
if _is_exponential(lhs, symbol):
result = _solve_exponential(lhs, rhs, symbol, domain)
# check if it is logarithmic type equation
elif _is_logarithmic(lhs, symbol):
result = _solve_logarithm(lhs, rhs, symbol, domain)
return result
result = ConditionSet(symbol, Eq(f, 0), domain)
# invert_complex handles the call to the desired inverter based
# on the domain specified.
lhs, rhs_s = invert_complex(f, 0, symbol, domain)
if isinstance(rhs_s, FiniteSet):
assert (len(rhs_s.args)) == 1
rhs = rhs_s.args[0]
if lhs.is_Add:
result = add_type(lhs, rhs, symbol, domain)
else:
result = rhs_s
return result
def solveset(f, symbol=None, domain=S.Complexes):
r"""Solves a given inequality or equation with set as output
Parameters
==========
f : Expr or a relational.
The target equation or inequality
symbol : Symbol
The variable for which the equation is solved
domain : Set
The domain over which the equation is solved
Returns
=======
Set
A set of values for `symbol` for which `f` is True or is equal to
zero. An `EmptySet` is returned if `f` is False or nonzero.
A `ConditionSet` is returned as unsolved object if algorithms
to evaluate complete solution are not yet implemented.
`solveset` claims to be complete in the solution set that it returns.
Raises
======
NotImplementedError
The algorithms to solve inequalities in complex domain are
not yet implemented.
ValueError
The input is not valid.
RuntimeError
It is a bug, please report to the github issue tracker.
Notes
=====
Python interprets 0 and 1 as False and True, respectively, but
in this function they refer to solutions of an expression. So 0 and 1
return the Domain and EmptySet, respectively, while True and False
return the opposite (as they are assumed to be solutions of relational
expressions).
See Also
========
solveset_real: solver for real domain
solveset_complex: solver for complex domain
Examples
========
>>> from sympy import exp, sin, Symbol, pprint, S, Eq
>>> from sympy.solvers.solveset import solveset, solveset_real
* The default domain is complex. Not specifying a domain will lead
to the solving of the equation in the complex domain (and this
is not affected by the assumptions on the symbol):
>>> x = Symbol('x')
>>> pprint(solveset(exp(x) - 1, x), use_unicode=False)
{2*n*I*pi | n in Integers}
>>> x = Symbol('x', real=True)
>>> pprint(solveset(exp(x) - 1, x), use_unicode=False)
{2*n*I*pi | n in Integers}
* If you want to use `solveset` to solve the equation in the
real domain, provide a real domain. (Using ``solveset_real``
does this automatically.)
>>> R = S.Reals
>>> x = Symbol('x')
>>> solveset(exp(x) - 1, x, R)
FiniteSet(0)
>>> solveset_real(exp(x) - 1, x)
FiniteSet(0)
The solution is unaffected by assumptions on the symbol:
>>> p = Symbol('p', positive=True)
>>> pprint(solveset(p**2 - 4))
{-2, 2}
When a conditionSet is returned, symbols with assumptions that
would alter the set are replaced with more generic symbols:
>>> i = Symbol('i', imaginary=True)
>>> solveset(Eq(i**2 + i*sin(i), 1), i, domain=S.Reals)
ConditionSet(_R, Eq(_R**2 + _R*sin(_R) - 1, 0), Reals)
* Inequalities can be solved over the real domain only. Use of a complex
domain leads to a NotImplementedError.
>>> solveset(exp(x) > 1, x, R)
Interval.open(0, oo)
"""
f = sympify(f)
symbol = sympify(symbol)
if f is S.true:
return domain
if f is S.false:
return S.EmptySet
if not isinstance(f, (Expr, Relational, Number)):
raise ValueError("%s is not a valid SymPy expression" % f)
if not isinstance(symbol, (Expr, Relational)) and symbol is not None:
raise ValueError("%s is not a valid SymPy symbol" % (symbol,))
if not isinstance(domain, Set):
raise ValueError("%s is not a valid domain" %(domain))
free_symbols = f.free_symbols
if symbol is None and not free_symbols:
b = Eq(f, 0)
if b is S.true:
return domain
elif b is S.false:
return S.EmptySet
else:
raise NotImplementedError(filldedent('''
relationship between value and 0 is unknown: %s''' % b))
if symbol is None:
if len(free_symbols) == 1:
symbol = free_symbols.pop()
elif free_symbols:
raise ValueError(filldedent('''
The independent variable must be specified for a
multivariate equation.'''))
elif not isinstance(symbol, Symbol):
f, s, swap = recast_to_symbols([f], [symbol])
# the xreplace will be needed if a ConditionSet is returned
return solveset(f[0], s[0], domain).xreplace(swap)
# solveset should ignore assumptions on symbols
if symbol not in _rc:
x = _rc[0] if domain.is_subset(S.Reals) else _rc[1]
rv = solveset(f.xreplace({symbol: x}), x, domain)
# try to use the original symbol if possible
try:
_rv = rv.xreplace({x: symbol})
except TypeError:
_rv = rv
if rv.dummy_eq(_rv):
rv = _rv
return rv
# Abs has its own handling method which avoids the
# rewriting property that the first piece of abs(x)
# is for x >= 0 and the 2nd piece for x < 0 -- solutions
# can look better if the 2nd condition is x <= 0. Since
# the solution is a set, duplication of results is not
# an issue, e.g. {y, -y} when y is 0 will be {0}
f, mask = _masked(f, Abs)
f = f.rewrite(Piecewise) # everything that's not an Abs
for d, e in mask:
# everything *in* an Abs
e = e.func(e.args[0].rewrite(Piecewise))
f = f.xreplace({d: e})
f = piecewise_fold(f)
return _solveset(f, symbol, domain, _check=True)
def solveset_real(f, symbol):
return solveset(f, symbol, S.Reals)
def solveset_complex(f, symbol):
return solveset(f, symbol, S.Complexes)
def _solveset_multi(eqs, syms, domains):
'''Basic implementation of a multivariate solveset.
For internal use (not ready for public consumption)'''
rep = {}
for sym, dom in zip(syms, domains):
if dom is S.Reals:
rep[sym] = Symbol(sym.name, real=True)
eqs = [eq.subs(rep) for eq in eqs]
syms = [sym.subs(rep) for sym in syms]
syms = tuple(syms)
if len(eqs) == 0:
return ProductSet(*domains)
if len(syms) == 1:
sym = syms[0]
domain = domains[0]
solsets = [solveset(eq, sym, domain) for eq in eqs]
solset = Intersection(*solsets)
return ImageSet(Lambda((sym,), (sym,)), solset).doit()
eqs = sorted(eqs, key=lambda eq: len(eq.free_symbols & set(syms)))
for n in range(len(eqs)):
sols = []
all_handled = True
for sym in syms:
if sym not in eqs[n].free_symbols:
continue
sol = solveset(eqs[n], sym, domains[syms.index(sym)])
if isinstance(sol, FiniteSet):
i = syms.index(sym)
symsp = syms[:i] + syms[i+1:]
domainsp = domains[:i] + domains[i+1:]
eqsp = eqs[:n] + eqs[n+1:]
for s in sol:
eqsp_sub = [eq.subs(sym, s) for eq in eqsp]
sol_others = _solveset_multi(eqsp_sub, symsp, domainsp)
fun = Lambda((symsp,), symsp[:i] + (s,) + symsp[i:])
sols.append(ImageSet(fun, sol_others).doit())
else:
all_handled = False
if all_handled:
return Union(*sols)
def solvify(f, symbol, domain):
"""Solves an equation using solveset and returns the solution in accordance
with the `solve` output API.
Returns
=======
We classify the output based on the type of solution returned by `solveset`.
Solution | Output
----------------------------------------
FiniteSet | list
ImageSet, | list (if `f` is periodic)
Union |
Union | list (with FiniteSet)
EmptySet | empty list
Others | None
Raises
======
NotImplementedError
A ConditionSet is the input.
Examples
========
>>> from sympy.solvers.solveset import solvify
>>> from sympy.abc import x
>>> from sympy import S, tan, sin, exp
>>> solvify(x**2 - 9, x, S.Reals)
[-3, 3]
>>> solvify(sin(x) - 1, x, S.Reals)
[pi/2]
>>> solvify(tan(x), x, S.Reals)
[0]
>>> solvify(exp(x) - 1, x, S.Complexes)
>>> solvify(exp(x) - 1, x, S.Reals)
[0]
"""
solution_set = solveset(f, symbol, domain)
result = None
if solution_set is S.EmptySet:
result = []
elif isinstance(solution_set, ConditionSet):
raise NotImplementedError('solveset is unable to solve this equation.')
elif isinstance(solution_set, FiniteSet):
result = list(solution_set)
else:
period = periodicity(f, symbol)
if period is not None:
solutions = S.EmptySet
iter_solutions = ()
if isinstance(solution_set, ImageSet):
iter_solutions = (solution_set,)
elif isinstance(solution_set, Union):
if all(isinstance(i, ImageSet) for i in solution_set.args):
iter_solutions = solution_set.args
for solution in iter_solutions:
solutions += solution.intersect(Interval(0, period, False, True))
if isinstance(solutions, FiniteSet):
result = list(solutions)
else:
solution = solution_set.intersect(domain)
if isinstance(solution, Union):
# concerned about only FiniteSet with Union but not about ImageSet
# if required could be extend
if any(isinstance(i, FiniteSet) for i in solution.args):
result = [sol for soln in solution.args \
for sol in soln.args if isinstance(soln,FiniteSet)]
else:
return None
elif isinstance(solution, FiniteSet):
result += solution
return result
###############################################################################
################################ LINSOLVE #####################################
###############################################################################
def linear_coeffs(eq, *syms, **_kw):
"""Return a list whose elements are the coefficients of the
corresponding symbols in the sum of terms in ``eq``.
The additive constant is returned as the last element of the
list.
Raises
======
NonlinearError
The equation contains a nonlinear term
Examples
========
>>> from sympy.solvers.solveset import linear_coeffs
>>> from sympy.abc import x, y, z
>>> linear_coeffs(3*x + 2*y - 1, x, y)
[3, 2, -1]
It is not necessary to expand the expression:
>>> linear_coeffs(x + y*(z*(x*3 + 2) + 3), x)
[3*y*z + 1, y*(2*z + 3)]
But if there are nonlinear or cross terms -- even if they would
cancel after simplification -- an error is raised so the situation
does not pass silently past the caller's attention:
>>> eq = 1/x*(x - 1) + 1/x
>>> linear_coeffs(eq.expand(), x)
[0, 1]
>>> linear_coeffs(eq, x)
Traceback (most recent call last):
...
NonlinearError: nonlinear term encountered: 1/x
>>> linear_coeffs(x*(y + 1) - x*y, x, y)
Traceback (most recent call last):
...
NonlinearError: nonlinear term encountered: x*(y + 1)
"""
d = defaultdict(list)
eq = _sympify(eq)
symset = set(syms)
has = eq.free_symbols & symset
if not has:
return [S.Zero]*len(syms) + [eq]
c, terms = eq.as_coeff_add(*has)
d[0].extend(Add.make_args(c))
for t in terms:
m, f = t.as_coeff_mul(*has)
if len(f) != 1:
break
f = f[0]
if f in symset:
d[f].append(m)
elif f.is_Add:
d1 = linear_coeffs(f, *has, **{'dict': True})
d[0].append(m*d1.pop(0))
for xf, vf in d1.items():
d[xf].append(m*vf)
else:
break
else:
for k, v in d.items():
d[k] = Add(*v)
if not _kw:
return [d.get(s, S.Zero) for s in syms] + [d[0]]
return d # default is still list but this won't matter
raise NonlinearError('nonlinear term encountered: %s' % t)
def linear_eq_to_matrix(equations, *symbols):
r"""
Converts a given System of Equations into Matrix form.
Here `equations` must be a linear system of equations in
`symbols`. Element M[i, j] corresponds to the coefficient
of the jth symbol in the ith equation.
The Matrix form corresponds to the augmented matrix form.
For example:
.. math:: 4x + 2y + 3z = 1
.. math:: 3x + y + z = -6
.. math:: 2x + 4y + 9z = 2
This system would return `A` & `b` as given below:
::
[ 4 2 3 ] [ 1 ]
A = [ 3 1 1 ] b = [-6 ]
[ 2 4 9 ] [ 2 ]
The only simplification performed is to convert
`Eq(a, b) -> a - b`.
Raises
======
NonlinearError
The equations contain a nonlinear term.
ValueError
The symbols are not given or are not unique.
Examples
========
>>> from sympy import linear_eq_to_matrix, symbols
>>> c, x, y, z = symbols('c, x, y, z')
The coefficients (numerical or symbolic) of the symbols will
be returned as matrices:
>>> eqns = [c*x + z - 1 - c, y + z, x - y]
>>> A, b = linear_eq_to_matrix(eqns, [x, y, z])
>>> A
Matrix([
[c, 0, 1],
[0, 1, 1],
[1, -1, 0]])
>>> b
Matrix([
[c + 1],
[ 0],
[ 0]])
This routine does not simplify expressions and will raise an error
if nonlinearity is encountered:
>>> eqns = [
... (x**2 - 3*x)/(x - 3) - 3,
... y**2 - 3*y - y*(y - 4) + x - 4]
>>> linear_eq_to_matrix(eqns, [x, y])
Traceback (most recent call last):
...
NonlinearError:
The term (x**2 - 3*x)/(x - 3) is nonlinear in {x, y}
Simplifying these equations will discard the removable singularity
in the first, reveal the linear structure of the second:
>>> [e.simplify() for e in eqns]
[x - 3, x + y - 4]
Any such simplification needed to eliminate nonlinear terms must
be done before calling this routine.
"""
if not symbols:
raise ValueError(filldedent('''
Symbols must be given, for which coefficients
are to be found.
'''))
if hasattr(symbols[0], '__iter__'):
symbols = symbols[0]
for i in symbols:
if not isinstance(i, Symbol):
raise ValueError(filldedent('''
Expecting a Symbol but got %s
''' % i))
if has_dups(symbols):
raise ValueError('Symbols must be unique')
equations = sympify(equations)
if isinstance(equations, MatrixBase):
equations = list(equations)
elif isinstance(equations, (Expr, Eq)):
equations = [equations]
elif not is_sequence(equations):
raise ValueError(filldedent('''
Equation(s) must be given as a sequence, Expr,
Eq or Matrix.
'''))
A, b = [], []
for i, f in enumerate(equations):
if isinstance(f, Equality):
f = f.rewrite(Add, evaluate=False)
coeff_list = linear_coeffs(f, *symbols)
b.append(-coeff_list.pop())
A.append(coeff_list)
A, b = map(Matrix, (A, b))
return A, b
def linsolve(system, *symbols):
r"""
Solve system of N linear equations with M variables; both
underdetermined and overdetermined systems are supported.
The possible number of solutions is zero, one or infinite.
Zero solutions throws a ValueError, whereas infinite
solutions are represented parametrically in terms of the given
symbols. For unique solution a FiniteSet of ordered tuples
is returned.
All Standard input formats are supported:
For the given set of Equations, the respective input types
are given below:
.. math:: 3x + 2y - z = 1
.. math:: 2x - 2y + 4z = -2
.. math:: 2x - y + 2z = 0
* Augmented Matrix Form, `system` given below:
::
[3 2 -1 1]
system = [2 -2 4 -2]
[2 -1 2 0]
* List Of Equations Form
`system = [3x + 2y - z - 1, 2x - 2y + 4z + 2, 2x - y + 2z]`
* Input A & b Matrix Form (from Ax = b) are given as below:
::
[3 2 -1 ] [ 1 ]
A = [2 -2 4 ] b = [ -2 ]
[2 -1 2 ] [ 0 ]
`system = (A, b)`
Symbols can always be passed but are actually only needed
when 1) a system of equations is being passed and 2) the
system is passed as an underdetermined matrix and one wants
to control the name of the free variables in the result.
An error is raised if no symbols are used for case 1, but if
no symbols are provided for case 2, internally generated symbols
will be provided. When providing symbols for case 2, there should
be at least as many symbols are there are columns in matrix A.
The algorithm used here is Gauss-Jordan elimination, which
results, after elimination, in a row echelon form matrix.
Returns
=======
A FiniteSet containing an ordered tuple of values for the
unknowns for which the `system` has a solution. (Wrapping
the tuple in FiniteSet is used to maintain a consistent
output format throughout solveset.)
Returns EmptySet, if the linear system is inconsistent.
Raises
======
ValueError
The input is not valid.
The symbols are not given.
Examples
========
>>> from sympy import Matrix, linsolve, symbols
>>> x, y, z = symbols("x, y, z")
>>> A = Matrix([[1, 2, 3], [4, 5, 6], [7, 8, 10]])
>>> b = Matrix([3, 6, 9])
>>> A
Matrix([
[1, 2, 3],
[4, 5, 6],
[7, 8, 10]])
>>> b
Matrix([
[3],
[6],
[9]])
>>> linsolve((A, b), [x, y, z])
FiniteSet((-1, 2, 0))
* Parametric Solution: In case the system is underdetermined, the
function will return a parametric solution in terms of the given
symbols. Those that are free will be returned unchanged. e.g. in
the system below, `z` is returned as the solution for variable z;
it can take on any value.
>>> A = Matrix([[1, 2, 3], [4, 5, 6], [7, 8, 9]])
>>> b = Matrix([3, 6, 9])
>>> linsolve((A, b), x, y, z)
FiniteSet((z - 1, 2 - 2*z, z))
If no symbols are given, internally generated symbols will be used.
The `tau0` in the 3rd position indicates (as before) that the 3rd
variable -- whatever it's named -- can take on any value:
>>> linsolve((A, b))
FiniteSet((tau0 - 1, 2 - 2*tau0, tau0))
* List of Equations as input
>>> Eqns = [3*x + 2*y - z - 1, 2*x - 2*y + 4*z + 2, - x + y/2 - z]
>>> linsolve(Eqns, x, y, z)
FiniteSet((1, -2, -2))
* Augmented Matrix as input
>>> aug = Matrix([[2, 1, 3, 1], [2, 6, 8, 3], [6, 8, 18, 5]])
>>> aug
Matrix([
[2, 1, 3, 1],
[2, 6, 8, 3],
[6, 8, 18, 5]])
>>> linsolve(aug, x, y, z)
FiniteSet((3/10, 2/5, 0))
* Solve for symbolic coefficients
>>> a, b, c, d, e, f = symbols('a, b, c, d, e, f')
>>> eqns = [a*x + b*y - c, d*x + e*y - f]
>>> linsolve(eqns, x, y)
FiniteSet(((-b*f + c*e)/(a*e - b*d), (a*f - c*d)/(a*e - b*d)))
* A degenerate system returns solution as set of given
symbols.
>>> system = Matrix(([0, 0, 0], [0, 0, 0], [0, 0, 0]))
>>> linsolve(system, x, y)
FiniteSet((x, y))
* For an empty system linsolve returns empty set
>>> linsolve([], x)
EmptySet
* An error is raised if, after expansion, any nonlinearity
is detected:
>>> linsolve([x*(1/x - 1), (y - 1)**2 - y**2 + 1], x, y)
FiniteSet((1, 1))
>>> linsolve([x**2 - 1], x)
Traceback (most recent call last):
...
NonlinearError:
nonlinear term encountered: x**2
"""
if not system:
return S.EmptySet
# If second argument is an iterable
if symbols and hasattr(symbols[0], '__iter__'):
symbols = symbols[0]
sym_gen = isinstance(symbols, GeneratorType)
b = None # if we don't get b the input was bad
# unpack system
if hasattr(system, '__iter__'):
# 1). (A, b)
if len(system) == 2 and isinstance(system[0], MatrixBase):
A, b = system
# 2). (eq1, eq2, ...)
if not isinstance(system[0], MatrixBase):
if sym_gen or not symbols:
raise ValueError(filldedent('''
When passing a system of equations, the explicit
symbols for which a solution is being sought must
be given as a sequence, too.
'''))
#
# Pass to the sparse solver implemented in polys. It is important
# that we do not attempt to convert the equations to a matrix
# because that would be very inefficient for large sparse systems
# of equations.
#
eqs = system
eqs = [sympify(eq) for eq in eqs]
try:
sol = _linsolve(eqs, symbols)
except PolyNonlinearError as exc:
# e.g. cos(x) contains an element of the set of generators
raise NonlinearError(str(exc))
if sol is None:
return S.EmptySet
sol = FiniteSet(Tuple(*(sol.get(sym, sym) for sym in symbols)))
return sol
elif isinstance(system, MatrixBase) and not (
symbols and not isinstance(symbols, GeneratorType) and
isinstance(symbols[0], MatrixBase)):
# 3). A augmented with b
A, b = system[:, :-1], system[:, -1:]
if b is None:
raise ValueError("Invalid arguments")
if sym_gen:
symbols = [next(symbols) for i in range(A.cols)]
if any(set(symbols) & (A.free_symbols | b.free_symbols)):
raise ValueError(filldedent('''
At least one of the symbols provided
already appears in the system to be solved.
One way to avoid this is to use Dummy symbols in
the generator, e.g. numbered_symbols('%s', cls=Dummy)
''' % symbols[0].name.rstrip('1234567890')))
if not symbols:
symbols = [Dummy() for _ in range(A.cols)]
name = _uniquely_named_symbol('tau', (A, b),
compare=lambda i: str(i).rstrip('1234567890')).name
gen = numbered_symbols(name)
else:
gen = None
# This is just a wrapper for solve_lin_sys
eqs = []
rows = A.tolist()
for rowi, bi in zip(rows, b):
terms = [elem * sym for elem, sym in zip(rowi, symbols) if elem]
terms.append(-bi)
eqs.append(Add(*terms))
eqs, ring = sympy_eqs_to_ring(eqs, symbols)
sol = solve_lin_sys(eqs, ring, _raw=False)
if sol is None:
return S.EmptySet
#sol = {sym:val for sym, val in sol.items() if sym != val}
sol = FiniteSet(Tuple(*(sol.get(sym, sym) for sym in symbols)))
if gen is not None:
solsym = sol.free_symbols
rep = {sym: next(gen) for sym in symbols if sym in solsym}
sol = sol.subs(rep)
return sol
##############################################################################
# ------------------------------nonlinsolve ---------------------------------#
##############################################################################
def _return_conditionset(eqs, symbols):
# return conditionset
eqs = (Eq(lhs, 0) for lhs in eqs)
condition_set = ConditionSet(
Tuple(*symbols), And(*eqs), S.Complexes**len(symbols))
return condition_set
def substitution(system, symbols, result=[{}], known_symbols=[],
exclude=[], all_symbols=None):
r"""
Solves the `system` using substitution method. It is used in
`nonlinsolve`. This will be called from `nonlinsolve` when any
equation(s) is non polynomial equation.
Parameters
==========
system : list of equations
The target system of equations
symbols : list of symbols to be solved.
The variable(s) for which the system is solved
known_symbols : list of solved symbols
Values are known for these variable(s)
result : An empty list or list of dict
If No symbol values is known then empty list otherwise
symbol as keys and corresponding value in dict.
exclude : Set of expression.
Mostly denominator expression(s) of the equations of the system.
Final solution should not satisfy these expressions.
all_symbols : known_symbols + symbols(unsolved).
Returns
=======
A FiniteSet of ordered tuple of values of `all_symbols` for which the
`system` has solution. Order of values in the tuple is same as symbols
present in the parameter `all_symbols`. If parameter `all_symbols` is None
then same as symbols present in the parameter `symbols`.
Please note that general FiniteSet is unordered, the solution returned
here is not simply a FiniteSet of solutions, rather it is a FiniteSet of
ordered tuple, i.e. the first & only argument to FiniteSet is a tuple of
solutions, which is ordered, & hence the returned solution is ordered.
Also note that solution could also have been returned as an ordered tuple,
FiniteSet is just a wrapper `{}` around the tuple. It has no other
significance except for the fact it is just used to maintain a consistent
output format throughout the solveset.
Raises
======
ValueError
The input is not valid.
The symbols are not given.
AttributeError
The input symbols are not `Symbol` type.
Examples
========
>>> from sympy.core.symbol import symbols
>>> x, y = symbols('x, y', real=True)
>>> from sympy.solvers.solveset import substitution
>>> substitution([x + y], [x], [{y: 1}], [y], set([]), [x, y])
FiniteSet((-1, 1))
* when you want soln should not satisfy eq `x + 1 = 0`
>>> substitution([x + y], [x], [{y: 1}], [y], set([x + 1]), [y, x])
EmptySet
>>> substitution([x + y], [x], [{y: 1}], [y], set([x - 1]), [y, x])
FiniteSet((1, -1))
>>> substitution([x + y - 1, y - x**2 + 5], [x, y])
FiniteSet((-3, 4), (2, -1))
* Returns both real and complex solution
>>> x, y, z = symbols('x, y, z')
>>> from sympy import exp, sin
>>> substitution([exp(x) - sin(y), y**2 - 4], [x, y])
FiniteSet((ImageSet(Lambda(_n, 2*_n*I*pi + log(sin(2))), Integers), 2),
(ImageSet(Lambda(_n, I*(2*_n*pi + pi) + log(sin(2))), Integers), -2))
>>> eqs = [z**2 + exp(2*x) - sin(y), -3 + exp(-y)]
>>> substitution(eqs, [y, z])
FiniteSet((-log(3), sqrt(-exp(2*x) - sin(log(3)))),
(-log(3), -sqrt(-exp(2*x) - sin(log(3)))),
(ImageSet(Lambda(_n, 2*_n*I*pi - log(3)), Integers),
ImageSet(Lambda(_n, sqrt(-exp(2*x) + sin(2*_n*I*pi - log(3)))), Integers)),
(ImageSet(Lambda(_n, 2*_n*I*pi - log(3)), Integers),
ImageSet(Lambda(_n, -sqrt(-exp(2*x) + sin(2*_n*I*pi - log(3)))), Integers)))
"""
from sympy import Complement
from sympy.core.compatibility import is_sequence
if not system:
return S.EmptySet
if not symbols:
msg = ('Symbols must be given, for which solution of the '
'system is to be found.')
raise ValueError(filldedent(msg))
if not is_sequence(symbols):
msg = ('symbols should be given as a sequence, e.g. a list.'
'Not type %s: %s')
raise TypeError(filldedent(msg % (type(symbols), symbols)))
if not getattr(symbols[0], 'is_Symbol', False):
msg = ('Iterable of symbols must be given as '
'second argument, not type %s: %s')
raise ValueError(filldedent(msg % (type(symbols[0]), symbols[0])))
# By default `all_symbols` will be same as `symbols`
if all_symbols is None:
all_symbols = symbols
old_result = result
# storing complements and intersection for particular symbol
complements = {}
intersections = {}
# when total_solveset_call equals total_conditionset
# it means that solveset failed to solve all eqs.
total_conditionset = -1
total_solveset_call = -1
def _unsolved_syms(eq, sort=False):
"""Returns the unsolved symbol present
in the equation `eq`.
"""
free = eq.free_symbols
unsolved = (free - set(known_symbols)) & set(all_symbols)
if sort:
unsolved = list(unsolved)
unsolved.sort(key=default_sort_key)
return unsolved
# end of _unsolved_syms()
# sort such that equation with the fewest potential symbols is first.
# means eq with less number of variable first in the list.
eqs_in_better_order = list(
ordered(system, lambda _: len(_unsolved_syms(_))))
def add_intersection_complement(result, intersection_dict, complement_dict):
# If solveset has returned some intersection/complement
# for any symbol, it will be added in the final solution.
final_result = []
for res in result:
res_copy = res
for key_res, value_res in res.items():
intersect_set, complement_set = None, None
for key_sym, value_sym in intersection_dict.items():
if key_sym == key_res:
intersect_set = value_sym
for key_sym, value_sym in complement_dict.items():
if key_sym == key_res:
complement_set = value_sym
if intersect_set or complement_set:
new_value = FiniteSet(value_res)
if intersect_set and intersect_set != S.Complexes:
new_value = Intersection(new_value, intersect_set)
if complement_set:
new_value = Complement(new_value, complement_set)
if new_value is S.EmptySet:
res_copy = None
break
elif new_value.is_FiniteSet and len(new_value) == 1:
res_copy[key_res] = set(new_value).pop()
else:
res_copy[key_res] = new_value
if res_copy is not None:
final_result.append(res_copy)
return final_result
# end of def add_intersection_complement()
def _extract_main_soln(sym, sol, soln_imageset):
"""Separate the Complements, Intersections, ImageSet lambda expr and
its base_set. This function returns the unmasks sol from different classes
of sets and also returns the appended ImageSet elements in a
soln_imageset (dict: where key as unmasked element and value as ImageSet).
"""
# if there is union, then need to check
# Complement, Intersection, Imageset.
# Order should not be changed.
if isinstance(sol, ConditionSet):
# extracts any solution in ConditionSet
sol = sol.base_set
if isinstance(sol, Complement):
# extract solution and complement
complements[sym] = sol.args[1]
sol = sol.args[0]
# complement will be added at the end
# using `add_intersection_complement` method
# if there is union of Imageset or other in soln.
# no testcase is written for this if block
if isinstance(sol, Union):
sol_args = sol.args
sol = S.EmptySet
# We need in sequence so append finteset elements
# and then imageset or other.
for sol_arg2 in sol_args:
if isinstance(sol_arg2, FiniteSet):
sol += sol_arg2
else:
# ImageSet, Intersection, complement then
# append them directly
sol += FiniteSet(sol_arg2)
if isinstance(sol, Intersection):
# Interval/Set will be at 0th index always
if sol.args[0] not in (S.Reals, S.Complexes):
# Sometimes solveset returns soln with intersection
# S.Reals or S.Complexes. We don't consider that
# intersection.
intersections[sym] = sol.args[0]
sol = sol.args[1]
# after intersection and complement Imageset should
# be checked.
if isinstance(sol, ImageSet):
soln_imagest = sol
expr2 = sol.lamda.expr
sol = FiniteSet(expr2)
soln_imageset[expr2] = soln_imagest
if not isinstance(sol, FiniteSet):
sol = FiniteSet(sol)
return sol, soln_imageset
# end of def _extract_main_soln()
# helper function for _append_new_soln
def _check_exclude(rnew, imgset_yes):
rnew_ = rnew
if imgset_yes:
# replace all dummy variables (Imageset lambda variables)
# with zero before `checksol`. Considering fundamental soln
# for `checksol`.
rnew_copy = rnew.copy()
dummy_n = imgset_yes[0]
for key_res, value_res in rnew_copy.items():
rnew_copy[key_res] = value_res.subs(dummy_n, 0)
rnew_ = rnew_copy
# satisfy_exclude == true if it satisfies the expr of `exclude` list.
try:
# something like : `Mod(-log(3), 2*I*pi)` can't be
# simplified right now, so `checksol` returns `TypeError`.
# when this issue is fixed this try block should be
# removed. Mod(-log(3), 2*I*pi) == -log(3)
satisfy_exclude = any(
checksol(d, rnew_) for d in exclude)
except TypeError:
satisfy_exclude = None
return satisfy_exclude
# end of def _check_exclude()
# helper function for _append_new_soln
def _restore_imgset(rnew, original_imageset, newresult):
restore_sym = set(rnew.keys()) & \
set(original_imageset.keys())
for key_sym in restore_sym:
img = original_imageset[key_sym]
rnew[key_sym] = img
if rnew not in newresult:
newresult.append(rnew)
# end of def _restore_imgset()
def _append_eq(eq, result, res, delete_soln, n=None):
u = Dummy('u')
if n:
eq = eq.subs(n, 0)
satisfy = eq if eq in (True, False) else checksol(u, u, eq, minimal=True)
if satisfy is False:
delete_soln = True
res = {}
else:
result.append(res)
return result, res, delete_soln
def _append_new_soln(rnew, sym, sol, imgset_yes, soln_imageset,
original_imageset, newresult, eq=None):
"""If `rnew` (A dict <symbol: soln>) contains valid soln
append it to `newresult` list.
`imgset_yes` is (base, dummy_var) if there was imageset in previously
calculated result(otherwise empty tuple). `original_imageset` is dict
of imageset expr and imageset from this result.
`soln_imageset` dict of imageset expr and imageset of new soln.
"""
satisfy_exclude = _check_exclude(rnew, imgset_yes)
delete_soln = False
# soln should not satisfy expr present in `exclude` list.
if not satisfy_exclude:
local_n = None
# if it is imageset
if imgset_yes:
local_n = imgset_yes[0]
base = imgset_yes[1]
if sym and sol:
# when `sym` and `sol` is `None` means no new
# soln. In that case we will append rnew directly after
# substituting original imagesets in rnew values if present
# (second last line of this function using _restore_imgset)
dummy_list = list(sol.atoms(Dummy))
# use one dummy `n` which is in
# previous imageset
local_n_list = [
local_n for i in range(
0, len(dummy_list))]
dummy_zip = zip(dummy_list, local_n_list)
lam = Lambda(local_n, sol.subs(dummy_zip))
rnew[sym] = ImageSet(lam, base)
if eq is not None:
newresult, rnew, delete_soln = _append_eq(
eq, newresult, rnew, delete_soln, local_n)
elif eq is not None:
newresult, rnew, delete_soln = _append_eq(
eq, newresult, rnew, delete_soln)
elif sol in soln_imageset.keys():
rnew[sym] = soln_imageset[sol]
# restore original imageset
_restore_imgset(rnew, original_imageset, newresult)
else:
newresult.append(rnew)
elif satisfy_exclude:
delete_soln = True
rnew = {}
_restore_imgset(rnew, original_imageset, newresult)
return newresult, delete_soln
# end of def _append_new_soln()
def _new_order_result(result, eq):
# separate first, second priority. `res` that makes `eq` value equals
# to zero, should be used first then other result(second priority).
# If it is not done then we may miss some soln.
first_priority = []
second_priority = []
for res in result:
if not any(isinstance(val, ImageSet) for val in res.values()):
if eq.subs(res) == 0:
first_priority.append(res)
else:
second_priority.append(res)
if first_priority or second_priority:
return first_priority + second_priority
return result
def _solve_using_known_values(result, solver):
"""Solves the system using already known solution
(result contains the dict <symbol: value>).
solver is `solveset_complex` or `solveset_real`.
"""
# stores imageset <expr: imageset(Lambda(n, expr), base)>.
soln_imageset = {}
total_solvest_call = 0
total_conditionst = 0
# sort such that equation with the fewest potential symbols is first.
# means eq with less variable first
for index, eq in enumerate(eqs_in_better_order):
newresult = []
original_imageset = {}
# if imageset expr is used to solve other symbol
imgset_yes = False
result = _new_order_result(result, eq)
for res in result:
got_symbol = set() # symbols solved in one iteration
# find the imageset and use its expr.
for key_res, value_res in res.items():
if isinstance(value_res, ImageSet):
res[key_res] = value_res.lamda.expr
original_imageset[key_res] = value_res
dummy_n = value_res.lamda.expr.atoms(Dummy).pop()
(base,) = value_res.base_sets
imgset_yes = (dummy_n, base)
# update eq with everything that is known so far
eq2 = eq.subs(res).expand()
unsolved_syms = _unsolved_syms(eq2, sort=True)
if not unsolved_syms:
if res:
newresult, delete_res = _append_new_soln(
res, None, None, imgset_yes, soln_imageset,
original_imageset, newresult, eq2)
if delete_res:
# `delete_res` is true, means substituting `res` in
# eq2 doesn't return `zero` or deleting the `res`
# (a soln) since it staisfies expr of `exclude`
# list.
result.remove(res)
continue # skip as it's independent of desired symbols
depen1, depen2 = (eq2.rewrite(Add)).as_independent(*unsolved_syms)
if (depen1.has(Abs) or depen2.has(Abs)) and solver == solveset_complex:
# Absolute values cannot be inverted in the
# complex domain
continue
soln_imageset = {}
for sym in unsolved_syms:
not_solvable = False
try:
soln = solver(eq2, sym)
total_solvest_call += 1
soln_new = S.EmptySet
if isinstance(soln, Complement):
# separate solution and complement
complements[sym] = soln.args[1]
soln = soln.args[0]
# complement will be added at the end
if isinstance(soln, Intersection):
# Interval will be at 0th index always
if soln.args[0] != Interval(-oo, oo):
# sometimes solveset returns soln
# with intersection S.Reals, to confirm that
# soln is in domain=S.Reals
intersections[sym] = soln.args[0]
soln_new += soln.args[1]
soln = soln_new if soln_new else soln
if index > 0 and solver == solveset_real:
# one symbol's real soln , another symbol may have
# corresponding complex soln.
if not isinstance(soln, (ImageSet, ConditionSet)):
soln += solveset_complex(eq2, sym)
except NotImplementedError:
# If sovleset is not able to solve equation `eq2`. Next
# time we may get soln using next equation `eq2`
continue
if isinstance(soln, ConditionSet):
if soln.base_set in (S.Reals, S.Complexes):
soln = S.EmptySet
# don't do `continue` we may get soln
# in terms of other symbol(s)
not_solvable = True
total_conditionst += 1
else:
soln = soln.base_set
if soln is not S.EmptySet:
soln, soln_imageset = _extract_main_soln(
sym, soln, soln_imageset)
for sol in soln:
# sol is not a `Union` since we checked it
# before this loop
sol, soln_imageset = _extract_main_soln(
sym, sol, soln_imageset)
sol = set(sol).pop()
free = sol.free_symbols
if got_symbol and any([
ss in free for ss in got_symbol
]):
# sol depends on previously solved symbols
# then continue
continue
rnew = res.copy()
# put each solution in res and append the new result
# in the new result list (solution for symbol `s`)
# along with old results.
for k, v in res.items():
if isinstance(v, Expr):
# if any unsolved symbol is present
# Then subs known value
rnew[k] = v.subs(sym, sol)
# and add this new solution
if sol in soln_imageset.keys():
# replace all lambda variables with 0.
imgst = soln_imageset[sol]
rnew[sym] = imgst.lamda(
*[0 for i in range(0, len(
imgst.lamda.variables))])
else:
rnew[sym] = sol
newresult, delete_res = _append_new_soln(
rnew, sym, sol, imgset_yes, soln_imageset,
original_imageset, newresult)
if delete_res:
# deleting the `res` (a soln) since it staisfies
# eq of `exclude` list
result.remove(res)
# solution got for sym
if not not_solvable:
got_symbol.add(sym)
# next time use this new soln
if newresult:
result = newresult
return result, total_solvest_call, total_conditionst
# end def _solve_using_know_values()
new_result_real, solve_call1, cnd_call1 = _solve_using_known_values(
old_result, solveset_real)
new_result_complex, solve_call2, cnd_call2 = _solve_using_known_values(
old_result, solveset_complex)
# If total_solveset_call is equal to total_conditionset
# then solveset failed to solve all of the equations.
# In this case we return a ConditionSet here.
total_conditionset += (cnd_call1 + cnd_call2)
total_solveset_call += (solve_call1 + solve_call2)
if total_conditionset == total_solveset_call and total_solveset_call != -1:
return _return_conditionset(eqs_in_better_order, all_symbols)
# don't keep duplicate solutions
filtered_complex = []
for i in list(new_result_complex):
for j in list(new_result_real):
if i.keys() != j.keys():
continue
if all(a.dummy_eq(b) for a, b in zip(i.values(), j.values()) \
if type(a) != int or type(b) != int):
break
else:
filtered_complex.append(i)
# overall result
result = new_result_real + filtered_complex
result_all_variables = []
result_infinite = []
for res in result:
if not res:
# means {None : None}
continue
# If length < len(all_symbols) means infinite soln.
# Some or all the soln is dependent on 1 symbol.
# eg. {x: y+2} then final soln {x: y+2, y: y}
if len(res) < len(all_symbols):
solved_symbols = res.keys()
unsolved = list(filter(
lambda x: x not in solved_symbols, all_symbols))
for unsolved_sym in unsolved:
res[unsolved_sym] = unsolved_sym
result_infinite.append(res)
if res not in result_all_variables:
result_all_variables.append(res)
if result_infinite:
# we have general soln
# eg : [{x: -1, y : 1}, {x : -y , y: y}] then
# return [{x : -y, y : y}]
result_all_variables = result_infinite
if intersections or complements:
result_all_variables = add_intersection_complement(
result_all_variables, intersections, complements)
# convert to ordered tuple
result = S.EmptySet
for r in result_all_variables:
temp = [r[symb] for symb in all_symbols]
result += FiniteSet(tuple(temp))
return result
# end of def substitution()
def _solveset_work(system, symbols):
soln = solveset(system[0], symbols[0])
if isinstance(soln, FiniteSet):
_soln = FiniteSet(*[tuple((s,)) for s in soln])
return _soln
else:
return FiniteSet(tuple(FiniteSet(soln)))
def _handle_positive_dimensional(polys, symbols, denominators):
from sympy.polys.polytools import groebner
# substitution method where new system is groebner basis of the system
_symbols = list(symbols)
_symbols.sort(key=default_sort_key)
basis = groebner(polys, _symbols, polys=True)
new_system = []
for poly_eq in basis:
new_system.append(poly_eq.as_expr())
result = [{}]
result = substitution(
new_system, symbols, result, [],
denominators)
return result
# end of def _handle_positive_dimensional()
def _handle_zero_dimensional(polys, symbols, system):
# solve 0 dimensional poly system using `solve_poly_system`
result = solve_poly_system(polys, *symbols)
# May be some extra soln is added because
# we used `unrad` in `_separate_poly_nonpoly`, so
# need to check and remove if it is not a soln.
result_update = S.EmptySet
for res in result:
dict_sym_value = dict(list(zip(symbols, res)))
if all(checksol(eq, dict_sym_value) for eq in system):
result_update += FiniteSet(res)
return result_update
# end of def _handle_zero_dimensional()
def _separate_poly_nonpoly(system, symbols):
polys = []
polys_expr = []
nonpolys = []
denominators = set()
poly = None
for eq in system:
# Store denom expression if it contains symbol
denominators.update(_simple_dens(eq, symbols))
# try to remove sqrt and rational power
without_radicals = unrad(simplify(eq))
if without_radicals:
eq_unrad, cov = without_radicals
if not cov:
eq = eq_unrad
if isinstance(eq, Expr):
eq = eq.as_numer_denom()[0]
poly = eq.as_poly(*symbols, extension=True)
elif simplify(eq).is_number:
continue
if poly is not None:
polys.append(poly)
polys_expr.append(poly.as_expr())
else:
nonpolys.append(eq)
return polys, polys_expr, nonpolys, denominators
# end of def _separate_poly_nonpoly()
def nonlinsolve(system, *symbols):
r"""
Solve system of N nonlinear equations with M variables, which means both
under and overdetermined systems are supported. Positive dimensional
system is also supported (A system with infinitely many solutions is said
to be positive-dimensional). In Positive dimensional system solution will
be dependent on at least one symbol. Returns both real solution
and complex solution(If system have). The possible number of solutions
is zero, one or infinite.
Parameters
==========
system : list of equations
The target system of equations
symbols : list of Symbols
symbols should be given as a sequence eg. list
Returns
=======
A FiniteSet of ordered tuple of values of `symbols` for which the `system`
has solution. Order of values in the tuple is same as symbols present in
the parameter `symbols`.
Please note that general FiniteSet is unordered, the solution returned
here is not simply a FiniteSet of solutions, rather it is a FiniteSet of
ordered tuple, i.e. the first & only argument to FiniteSet is a tuple of
solutions, which is ordered, & hence the returned solution is ordered.
Also note that solution could also have been returned as an ordered tuple,
FiniteSet is just a wrapper `{}` around the tuple. It has no other
significance except for the fact it is just used to maintain a consistent
output format throughout the solveset.
For the given set of Equations, the respective input types
are given below:
.. math:: x*y - 1 = 0
.. math:: 4*x**2 + y**2 - 5 = 0
`system = [x*y - 1, 4*x**2 + y**2 - 5]`
`symbols = [x, y]`
Raises
======
ValueError
The input is not valid.
The symbols are not given.
AttributeError
The input symbols are not `Symbol` type.
Examples
========
>>> from sympy.core.symbol import symbols
>>> from sympy.solvers.solveset import nonlinsolve
>>> x, y, z = symbols('x, y, z', real=True)
>>> nonlinsolve([x*y - 1, 4*x**2 + y**2 - 5], [x, y])
FiniteSet((-1, -1), (-1/2, -2), (1/2, 2), (1, 1))
1. Positive dimensional system and complements:
>>> from sympy import pprint
>>> from sympy.polys.polytools import is_zero_dimensional
>>> a, b, c, d = symbols('a, b, c, d', extended_real=True)
>>> eq1 = a + b + c + d
>>> eq2 = a*b + b*c + c*d + d*a
>>> eq3 = a*b*c + b*c*d + c*d*a + d*a*b
>>> eq4 = a*b*c*d - 1
>>> system = [eq1, eq2, eq3, eq4]
>>> is_zero_dimensional(system)
False
>>> pprint(nonlinsolve(system, [a, b, c, d]), use_unicode=False)
-1 1 1 -1
{(---, -d, -, {d} \ {0}), (-, -d, ---, {d} \ {0})}
d d d d
>>> nonlinsolve([(x+y)**2 - 4, x + y - 2], [x, y])
FiniteSet((2 - y, y))
2. If some of the equations are non-polynomial then `nonlinsolve`
will call the `substitution` function and return real and complex solutions,
if present.
>>> from sympy import exp, sin
>>> nonlinsolve([exp(x) - sin(y), y**2 - 4], [x, y])
FiniteSet((ImageSet(Lambda(_n, 2*_n*I*pi + log(sin(2))), Integers), 2),
(ImageSet(Lambda(_n, I*(2*_n*pi + pi) + log(sin(2))), Integers), -2))
3. If system is non-linear polynomial and zero-dimensional then it
returns both solution (real and complex solutions, if present) using
`solve_poly_system`:
>>> from sympy import sqrt
>>> nonlinsolve([x**2 - 2*y**2 -2, x*y - 2], [x, y])
FiniteSet((-2, -1), (2, 1), (-sqrt(2)*I, sqrt(2)*I), (sqrt(2)*I, -sqrt(2)*I))
4. `nonlinsolve` can solve some linear (zero or positive dimensional)
system (because it uses the `groebner` function to get the
groebner basis and then uses the `substitution` function basis as the
new `system`). But it is not recommended to solve linear system using
`nonlinsolve`, because `linsolve` is better for general linear systems.
>>> nonlinsolve([x + 2*y -z - 3, x - y - 4*z + 9 , y + z - 4], [x, y, z])
FiniteSet((3*z - 5, 4 - z, z))
5. System having polynomial equations and only real solution is
solved using `solve_poly_system`:
>>> e1 = sqrt(x**2 + y**2) - 10
>>> e2 = sqrt(y**2 + (-x + 10)**2) - 3
>>> nonlinsolve((e1, e2), (x, y))
FiniteSet((191/20, -3*sqrt(391)/20), (191/20, 3*sqrt(391)/20))
>>> nonlinsolve([x**2 + 2/y - 2, x + y - 3], [x, y])
FiniteSet((1, 2), (1 - sqrt(5), 2 + sqrt(5)), (1 + sqrt(5), 2 - sqrt(5)))
>>> nonlinsolve([x**2 + 2/y - 2, x + y - 3], [y, x])
FiniteSet((2, 1), (2 - sqrt(5), 1 + sqrt(5)), (2 + sqrt(5), 1 - sqrt(5)))
6. It is better to use symbols instead of Trigonometric Function or
Function (e.g. replace `sin(x)` with symbol, replace `f(x)` with symbol
and so on. Get soln from `nonlinsolve` and then using `solveset` get
the value of `x`)
How nonlinsolve is better than old solver `_solve_system` :
===========================================================
1. A positive dimensional system solver : nonlinsolve can return
solution for positive dimensional system. It finds the
Groebner Basis of the positive dimensional system(calling it as
basis) then we can start solving equation(having least number of
variable first in the basis) using solveset and substituting that
solved solutions into other equation(of basis) to get solution in
terms of minimum variables. Here the important thing is how we
are substituting the known values and in which equations.
2. Real and Complex both solutions : nonlinsolve returns both real
and complex solution. If all the equations in the system are polynomial
then using `solve_poly_system` both real and complex solution is returned.
If all the equations in the system are not polynomial equation then goes to
`substitution` method with this polynomial and non polynomial equation(s),
to solve for unsolved variables. Here to solve for particular variable
solveset_real and solveset_complex is used. For both real and complex
solution function `_solve_using_know_values` is used inside `substitution`
function.(`substitution` function will be called when there is any non
polynomial equation(s) is present). When solution is valid then add its
general solution in the final result.
3. Complement and Intersection will be added if any : nonlinsolve maintains
dict for complements and Intersections. If solveset find complements or/and
Intersection with any Interval or set during the execution of
`substitution` function ,then complement or/and Intersection for that
variable is added before returning final solution.
"""
from sympy.polys.polytools import is_zero_dimensional
if not system:
return S.EmptySet
if not symbols:
msg = ('Symbols must be given, for which solution of the '
'system is to be found.')
raise ValueError(filldedent(msg))
if hasattr(symbols[0], '__iter__'):
symbols = symbols[0]
if not is_sequence(symbols) or not symbols:
msg = ('Symbols must be given, for which solution of the '
'system is to be found.')
raise IndexError(filldedent(msg))
system, symbols, swap = recast_to_symbols(system, symbols)
if swap:
soln = nonlinsolve(system, symbols)
return FiniteSet(*[tuple(i.xreplace(swap) for i in s) for s in soln])
if len(system) == 1 and len(symbols) == 1:
return _solveset_work(system, symbols)
# main code of def nonlinsolve() starts from here
polys, polys_expr, nonpolys, denominators = _separate_poly_nonpoly(
system, symbols)
if len(symbols) == len(polys):
# If all the equations in the system are poly
if is_zero_dimensional(polys, symbols):
# finite number of soln (Zero dimensional system)
try:
return _handle_zero_dimensional(polys, symbols, system)
except NotImplementedError:
# Right now it doesn't fail for any polynomial system of
# equation. If `solve_poly_system` fails then `substitution`
# method will handle it.
result = substitution(
polys_expr, symbols, exclude=denominators)
return result
# positive dimensional system
res = _handle_positive_dimensional(polys, symbols, denominators)
if res is EmptySet and any(not p.domain.is_Exact for p in polys):
raise NotImplementedError("Equation not in exact domain. Try converting to rational")
else:
return res
else:
# If all the equations are not polynomial.
# Use `substitution` method for the system
result = substitution(
polys_expr + nonpolys, symbols, exclude=denominators)
return result
|
014b39f65f4c07099f97f243629187fcca83b1ffa8fb02eaf29fa502c4c12f3c | """Utility functions for classifying and solving
ordinary and partial differential equations.
Contains
========
_preprocess
ode_order
_desolve
"""
from sympy.core import Pow
from sympy.core.function import Derivative, AppliedUndef
from sympy.core.relational import Equality
from sympy.core.symbol import Wild
def _preprocess(expr, func=None, hint='_Integral'):
"""Prepare expr for solving by making sure that differentiation
is done so that only func remains in unevaluated derivatives and
(if hint doesn't end with _Integral) that doit is applied to all
other derivatives. If hint is None, don't do any differentiation.
(Currently this may cause some simple differential equations to
fail.)
In case func is None, an attempt will be made to autodetect the
function to be solved for.
>>> from sympy.solvers.deutils import _preprocess
>>> from sympy import Derivative, Function
>>> from sympy.abc import x, y, z
>>> f, g = map(Function, 'fg')
If f(x)**p == 0 and p>0 then we can solve for f(x)=0
>>> _preprocess((f(x).diff(x)-4)**5, f(x))
(Derivative(f(x), x) - 4, f(x))
Apply doit to derivatives that contain more than the function
of interest:
>>> _preprocess(Derivative(f(x) + x, x))
(Derivative(f(x), x) + 1, f(x))
Do others if the differentiation variable(s) intersect with those
of the function of interest or contain the function of interest:
>>> _preprocess(Derivative(g(x), y, z), f(y))
(0, f(y))
>>> _preprocess(Derivative(f(y), z), f(y))
(0, f(y))
Do others if the hint doesn't end in '_Integral' (the default
assumes that it does):
>>> _preprocess(Derivative(g(x), y), f(x))
(Derivative(g(x), y), f(x))
>>> _preprocess(Derivative(f(x), y), f(x), hint='')
(0, f(x))
Don't do any derivatives if hint is None:
>>> eq = Derivative(f(x) + 1, x) + Derivative(f(x), y)
>>> _preprocess(eq, f(x), hint=None)
(Derivative(f(x) + 1, x) + Derivative(f(x), y), f(x))
If it's not clear what the function of interest is, it must be given:
>>> eq = Derivative(f(x) + g(x), x)
>>> _preprocess(eq, g(x))
(Derivative(f(x), x) + Derivative(g(x), x), g(x))
>>> try: _preprocess(eq)
... except ValueError: print("A ValueError was raised.")
A ValueError was raised.
"""
if isinstance(expr, Pow):
# if f(x)**p=0 then f(x)=0 (p>0)
if (expr.exp).is_positive:
expr = expr.base
derivs = expr.atoms(Derivative)
if not func:
funcs = set().union(*[d.atoms(AppliedUndef) for d in derivs])
if len(funcs) != 1:
raise ValueError('The function cannot be '
'automatically detected for %s.' % expr)
func = funcs.pop()
fvars = set(func.args)
if hint is None:
return expr, func
reps = [(d, d.doit()) for d in derivs if not hint.endswith('_Integral') or
d.has(func) or set(d.variables) & fvars]
eq = expr.subs(reps)
return eq, func
def ode_order(expr, func):
"""
Returns the order of a given differential
equation with respect to func.
This function is implemented recursively.
Examples
========
>>> from sympy import Function
>>> from sympy.solvers.deutils import ode_order
>>> from sympy.abc import x
>>> f, g = map(Function, ['f', 'g'])
>>> ode_order(f(x).diff(x, 2) + f(x).diff(x)**2 +
... f(x).diff(x), f(x))
2
>>> ode_order(f(x).diff(x, 2) + g(x).diff(x, 3), f(x))
2
>>> ode_order(f(x).diff(x, 2) + g(x).diff(x, 3), g(x))
3
"""
a = Wild('a', exclude=[func])
if expr.match(a):
return 0
if isinstance(expr, Derivative):
if expr.args[0] == func:
return len(expr.variables)
else:
order = 0
for arg in expr.args[0].args:
order = max(order, ode_order(arg, func) + len(expr.variables))
return order
else:
order = 0
for arg in expr.args:
order = max(order, ode_order(arg, func))
return order
def _desolve(eq, func=None, hint="default", ics=None, simplify=True, *, prep=True, **kwargs):
"""This is a helper function to dsolve and pdsolve in the ode
and pde modules.
If the hint provided to the function is "default", then a dict with
the following keys are returned
'func' - It provides the function for which the differential equation
has to be solved. This is useful when the expression has
more than one function in it.
'default' - The default key as returned by classifier functions in ode
and pde.py
'hint' - The hint given by the user for which the differential equation
is to be solved. If the hint given by the user is 'default',
then the value of 'hint' and 'default' is the same.
'order' - The order of the function as returned by ode_order
'match' - It returns the match as given by the classifier functions, for
the default hint.
If the hint provided to the function is not "default" and is not in
('all', 'all_Integral', 'best'), then a dict with the above mentioned keys
is returned along with the keys which are returned when dict in
classify_ode or classify_pde is set True
If the hint given is in ('all', 'all_Integral', 'best'), then this function
returns a nested dict, with the keys, being the set of classified hints
returned by classifier functions, and the values being the dict of form
as mentioned above.
Key 'eq' is a common key to all the above mentioned hints which returns an
expression if eq given by user is an Equality.
See Also
========
classify_ode(ode.py)
classify_pde(pde.py)
"""
if isinstance(eq, Equality):
eq = eq.lhs - eq.rhs
# preprocess the equation and find func if not given
if prep or func is None:
eq, func = _preprocess(eq, func)
prep = False
# type is an argument passed by the solve functions in ode and pde.py
# that identifies whether the function caller is an ordinary
# or partial differential equation. Accordingly corresponding
# changes are made in the function.
type = kwargs.get('type', None)
xi = kwargs.get('xi')
eta = kwargs.get('eta')
x0 = kwargs.get('x0', 0)
terms = kwargs.get('n')
if type == 'ode':
from sympy.solvers.ode import classify_ode, allhints
classifier = classify_ode
string = 'ODE '
dummy = ''
elif type == 'pde':
from sympy.solvers.pde import classify_pde, allhints
classifier = classify_pde
string = 'PDE '
dummy = 'p'
# Magic that should only be used internally. Prevents classify_ode from
# being called more than it needs to be by passing its results through
# recursive calls.
if kwargs.get('classify', True):
hints = classifier(eq, func, dict=True, ics=ics, xi=xi, eta=eta,
n=terms, x0=x0, hint=hint, prep=prep)
else:
# Here is what all this means:
#
# hint: The hint method given to _desolve() by the user.
# hints: The dictionary of hints that match the DE, along with other
# information (including the internal pass-through magic).
# default: The default hint to return, the first hint from allhints
# that matches the hint; obtained from classify_ode().
# match: Dictionary containing the match dictionary for each hint
# (the parts of the DE for solving). When going through the
# hints in "all", this holds the match string for the current
# hint.
# order: The order of the DE, as determined by ode_order().
hints = kwargs.get('hint',
{'default': hint,
hint: kwargs['match'],
'order': kwargs['order']})
if not hints['default']:
# classify_ode will set hints['default'] to None if no hints match.
if hint not in allhints and hint != 'default':
raise ValueError("Hint not recognized: " + hint)
elif hint not in hints['ordered_hints'] and hint != 'default':
raise ValueError(string + str(eq) + " does not match hint " + hint)
# If dsolve can't solve the purely algebraic equation then dsolve will raise
# ValueError
elif hints['order'] == 0:
raise ValueError(
str(eq) + " is not a solvable differential equation in " + str(func))
else:
raise NotImplementedError(dummy + "solve" + ": Cannot solve " + str(eq))
if hint == 'default':
return _desolve(eq, func, ics=ics, hint=hints['default'], simplify=simplify,
prep=prep, x0=x0, classify=False, order=hints['order'],
match=hints[hints['default']], xi=xi, eta=eta, n=terms, type=type)
elif hint in ('all', 'all_Integral', 'best'):
retdict = {}
gethints = set(hints) - {'order', 'default', 'ordered_hints'}
if hint == 'all_Integral':
for i in hints:
if i.endswith('_Integral'):
gethints.remove(i[:-len('_Integral')])
# special cases
for k in ["1st_homogeneous_coeff_best", "1st_power_series",
"lie_group", "2nd_power_series_ordinary", "2nd_power_series_regular"]:
if k in gethints:
gethints.remove(k)
for i in gethints:
sol = _desolve(eq, func, ics=ics, hint=i, x0=x0, simplify=simplify, prep=prep,
classify=False, n=terms, order=hints['order'], match=hints[i], type=type)
retdict[i] = sol
retdict['all'] = True
retdict['eq'] = eq
return retdict
elif hint not in allhints: # and hint not in ('default', 'ordered_hints'):
raise ValueError("Hint not recognized: " + hint)
elif hint not in hints:
raise ValueError(string + str(eq) + " does not match hint " + hint)
else:
# Key added to identify the hint needed to solve the equation
hints['hint'] = hint
hints.update({'func': func, 'eq': eq})
return hints
|
3f01748c3fbdde1dcfec8cfcf550eb2cf03fe17046c4ad84eb618a0430caf818 | """
This module contain solvers for all kinds of equations:
- algebraic or transcendental, use solve()
- recurrence, use rsolve()
- differential, use dsolve()
- nonlinear (numerically), use nsolve()
(you will need a good starting point)
"""
from sympy import divisors, binomial, expand_func
from sympy.core.assumptions import check_assumptions
from sympy.core.compatibility import (iterable, is_sequence, ordered,
default_sort_key)
from sympy.core.sympify import sympify
from sympy.core import (S, Add, Symbol, Equality, Dummy, Expr, Mul,
Pow, Unequality, Wild)
from sympy.core.exprtools import factor_terms
from sympy.core.function import (expand_mul, expand_log,
Derivative, AppliedUndef, UndefinedFunction, nfloat,
Function, expand_power_exp, _mexpand, expand)
from sympy.integrals.integrals import Integral
from sympy.core.numbers import ilcm, Float, Rational
from sympy.core.relational import Relational
from sympy.core.logic import fuzzy_not
from sympy.core.power import integer_log
from sympy.logic.boolalg import And, Or, BooleanAtom
from sympy.core.basic import preorder_traversal
from sympy.functions import (log, exp, LambertW, cos, sin, tan, acos, asin, atan,
Abs, re, im, arg, sqrt, atan2)
from sympy.functions.elementary.trigonometric import (TrigonometricFunction,
HyperbolicFunction)
from sympy.simplify import (simplify, collect, powsimp, posify, # type: ignore
powdenest, nsimplify, denom, logcombine, sqrtdenest, fraction,
separatevars)
from sympy.simplify.sqrtdenest import sqrt_depth
from sympy.simplify.fu import TR1, TR2i
from sympy.matrices.common import NonInvertibleMatrixError
from sympy.matrices import Matrix, zeros
from sympy.polys import roots, cancel, factor, Poly
from sympy.polys.polyerrors import GeneratorsNeeded, PolynomialError
from sympy.polys.solvers import sympy_eqs_to_ring, solve_lin_sys
from sympy.functions.elementary.piecewise import piecewise_fold, Piecewise
from sympy.utilities.lambdify import lambdify
from sympy.utilities.misc import filldedent
from sympy.utilities.iterables import (cartes, connected_components,
generate_bell, uniq, sift)
from sympy.utilities.decorator import conserve_mpmath_dps
from mpmath import findroot
from sympy.solvers.polysys import solve_poly_system
from sympy.solvers.inequalities import reduce_inequalities
from types import GeneratorType
from collections import defaultdict
import warnings
def recast_to_symbols(eqs, symbols):
"""
Return (e, s, d) where e and s are versions of *eqs* and
*symbols* in which any non-Symbol objects in *symbols* have
been replaced with generic Dummy symbols and d is a dictionary
that can be used to restore the original expressions.
Examples
========
>>> from sympy.solvers.solvers import recast_to_symbols
>>> from sympy import symbols, Function
>>> x, y = symbols('x y')
>>> fx = Function('f')(x)
>>> eqs, syms = [fx + 1, x, y], [fx, y]
>>> e, s, d = recast_to_symbols(eqs, syms); (e, s, d)
([_X0 + 1, x, y], [_X0, y], {_X0: f(x)})
The original equations and symbols can be restored using d:
>>> assert [i.xreplace(d) for i in eqs] == eqs
>>> assert [d.get(i, i) for i in s] == syms
"""
if not iterable(eqs) and iterable(symbols):
raise ValueError('Both eqs and symbols must be iterable')
new_symbols = list(symbols)
swap_sym = {}
for i, s in enumerate(symbols):
if not isinstance(s, Symbol) and s not in swap_sym:
swap_sym[s] = Dummy('X%d' % i)
new_symbols[i] = swap_sym[s]
new_f = []
for i in eqs:
isubs = getattr(i, 'subs', None)
if isubs is not None:
new_f.append(isubs(swap_sym))
else:
new_f.append(i)
swap_sym = {v: k for k, v in swap_sym.items()}
return new_f, new_symbols, swap_sym
def _ispow(e):
"""Return True if e is a Pow or is exp."""
return isinstance(e, Expr) and (e.is_Pow or isinstance(e, exp))
def _simple_dens(f, symbols):
# when checking if a denominator is zero, we can just check the
# base of powers with nonzero exponents since if the base is zero
# the power will be zero, too. To keep it simple and fast, we
# limit simplification to exponents that are Numbers
dens = set()
for d in denoms(f, symbols):
if d.is_Pow and d.exp.is_Number:
if d.exp.is_zero:
continue # foo**0 is never 0
d = d.base
dens.add(d)
return dens
def denoms(eq, *symbols):
"""
Return (recursively) set of all denominators that appear in *eq*
that contain any symbol in *symbols*; if *symbols* are not
provided then all denominators will be returned.
Examples
========
>>> from sympy.solvers.solvers import denoms
>>> from sympy.abc import x, y, z
>>> denoms(x/y)
{y}
>>> denoms(x/(y*z))
{y, z}
>>> denoms(3/x + y/z)
{x, z}
>>> denoms(x/2 + y/z)
{2, z}
If *symbols* are provided then only denominators containing
those symbols will be returned:
>>> denoms(1/x + 1/y + 1/z, y, z)
{y, z}
"""
pot = preorder_traversal(eq)
dens = set()
for p in pot:
# Here p might be Tuple or Relational
# Expr subtrees (e.g. lhs and rhs) will be traversed after by pot
if not isinstance(p, Expr):
continue
den = denom(p)
if den is S.One:
continue
for d in Mul.make_args(den):
dens.add(d)
if not symbols:
return dens
elif len(symbols) == 1:
if iterable(symbols[0]):
symbols = symbols[0]
rv = []
for d in dens:
free = d.free_symbols
if any(s in free for s in symbols):
rv.append(d)
return set(rv)
def checksol(f, symbol, sol=None, **flags):
"""
Checks whether sol is a solution of equation f == 0.
Explanation
===========
Input can be either a single symbol and corresponding value
or a dictionary of symbols and values. When given as a dictionary
and flag ``simplify=True``, the values in the dictionary will be
simplified. *f* can be a single equation or an iterable of equations.
A solution must satisfy all equations in *f* to be considered valid;
if a solution does not satisfy any equation, False is returned; if one or
more checks are inconclusive (and none are False) then None is returned.
Examples
========
>>> from sympy import symbols
>>> from sympy.solvers import checksol
>>> x, y = symbols('x,y')
>>> checksol(x**4 - 1, x, 1)
True
>>> checksol(x**4 - 1, x, 0)
False
>>> checksol(x**2 + y**2 - 5**2, {x: 3, y: 4})
True
To check if an expression is zero using ``checksol()``, pass it
as *f* and send an empty dictionary for *symbol*:
>>> checksol(x**2 + x - x*(x + 1), {})
True
None is returned if ``checksol()`` could not conclude.
flags:
'numerical=True (default)'
do a fast numerical check if ``f`` has only one symbol.
'minimal=True (default is False)'
a very fast, minimal testing.
'warn=True (default is False)'
show a warning if checksol() could not conclude.
'simplify=True (default)'
simplify solution before substituting into function and
simplify the function before trying specific simplifications
'force=True (default is False)'
make positive all symbols without assumptions regarding sign.
"""
from sympy.physics.units import Unit
minimal = flags.get('minimal', False)
if sol is not None:
sol = {symbol: sol}
elif isinstance(symbol, dict):
sol = symbol
else:
msg = 'Expecting (sym, val) or ({sym: val}, None) but got (%s, %s)'
raise ValueError(msg % (symbol, sol))
if iterable(f):
if not f:
raise ValueError('no functions to check')
rv = True
for fi in f:
check = checksol(fi, sol, **flags)
if check:
continue
if check is False:
return False
rv = None # don't return, wait to see if there's a False
return rv
if isinstance(f, Poly):
f = f.as_expr()
elif isinstance(f, (Equality, Unequality)):
if f.rhs in (S.true, S.false):
f = f.reversed
B, E = f.args
if isinstance(B, BooleanAtom):
f = f.subs(sol)
if not f.is_Boolean:
return
else:
f = f.rewrite(Add, evaluate=False)
if isinstance(f, BooleanAtom):
return bool(f)
elif not f.is_Relational and not f:
return True
if sol and not f.free_symbols & set(sol.keys()):
# if f(y) == 0, x=3 does not set f(y) to zero...nor does it not
return None
illegal = {S.NaN,
S.ComplexInfinity,
S.Infinity,
S.NegativeInfinity}
if any(sympify(v).atoms() & illegal for k, v in sol.items()):
return False
was = f
attempt = -1
numerical = flags.get('numerical', True)
while 1:
attempt += 1
if attempt == 0:
val = f.subs(sol)
if isinstance(val, Mul):
val = val.as_independent(Unit)[0]
if val.atoms() & illegal:
return False
elif attempt == 1:
if not val.is_number:
if not val.is_constant(*list(sol.keys()), simplify=not minimal):
return False
# there are free symbols -- simple expansion might work
_, val = val.as_content_primitive()
val = _mexpand(val.as_numer_denom()[0], recursive=True)
elif attempt == 2:
if minimal:
return
if flags.get('simplify', True):
for k in sol:
sol[k] = simplify(sol[k])
# start over without the failed expanded form, possibly
# with a simplified solution
val = simplify(f.subs(sol))
if flags.get('force', True):
val, reps = posify(val)
# expansion may work now, so try again and check
exval = _mexpand(val, recursive=True)
if exval.is_number:
# we can decide now
val = exval
else:
# if there are no radicals and no functions then this can't be
# zero anymore -- can it?
pot = preorder_traversal(expand_mul(val))
seen = set()
saw_pow_func = False
for p in pot:
if p in seen:
continue
seen.add(p)
if p.is_Pow and not p.exp.is_Integer:
saw_pow_func = True
elif p.is_Function:
saw_pow_func = True
elif isinstance(p, UndefinedFunction):
saw_pow_func = True
if saw_pow_func:
break
if saw_pow_func is False:
return False
if flags.get('force', True):
# don't do a zero check with the positive assumptions in place
val = val.subs(reps)
nz = fuzzy_not(val.is_zero)
if nz is not None:
# issue 5673: nz may be True even when False
# so these are just hacks to keep a false positive
# from being returned
# HACK 1: LambertW (issue 5673)
if val.is_number and val.has(LambertW):
# don't eval this to verify solution since if we got here,
# numerical must be False
return None
# add other HACKs here if necessary, otherwise we assume
# the nz value is correct
return not nz
break
if val == was:
continue
elif val.is_Rational:
return val == 0
if numerical and val.is_number:
return (abs(val.n(18).n(12, chop=True)) < 1e-9) is S.true
was = val
if flags.get('warn', False):
warnings.warn("\n\tWarning: could not verify solution %s." % sol)
# returns None if it can't conclude
# TODO: improve solution testing
def solve(f, *symbols, **flags):
r"""
Algebraically solves equations and systems of equations.
Explanation
===========
Currently supported:
- polynomial
- transcendental
- piecewise combinations of the above
- systems of linear and polynomial equations
- systems containing relational expressions
Examples
========
The output varies according to the input and can be seen by example:
>>> from sympy import solve, Poly, Eq, Function, exp
>>> from sympy.abc import x, y, z, a, b
>>> f = Function('f')
Boolean or univariate Relational:
>>> solve(x < 3)
(-oo < x) & (x < 3)
To always get a list of solution mappings, use flag dict=True:
>>> solve(x - 3, dict=True)
[{x: 3}]
>>> sol = solve([x - 3, y - 1], dict=True)
>>> sol
[{x: 3, y: 1}]
>>> sol[0][x]
3
>>> sol[0][y]
1
To get a list of *symbols* and set of solution(s) use flag set=True:
>>> solve([x**2 - 3, y - 1], set=True)
([x, y], {(-sqrt(3), 1), (sqrt(3), 1)})
Single expression and single symbol that is in the expression:
>>> solve(x - y, x)
[y]
>>> solve(x - 3, x)
[3]
>>> solve(Eq(x, 3), x)
[3]
>>> solve(Poly(x - 3), x)
[3]
>>> solve(x**2 - y**2, x, set=True)
([x], {(-y,), (y,)})
>>> solve(x**4 - 1, x, set=True)
([x], {(-1,), (1,), (-I,), (I,)})
Single expression with no symbol that is in the expression:
>>> solve(3, x)
[]
>>> solve(x - 3, y)
[]
Single expression with no symbol given. In this case, all free *symbols*
will be selected as potential *symbols* to solve for. If the equation is
univariate then a list of solutions is returned; otherwise - as is the case
when *symbols* are given as an iterable of length greater than 1 - a list of
mappings will be returned:
>>> solve(x - 3)
[3]
>>> solve(x**2 - y**2)
[{x: -y}, {x: y}]
>>> solve(z**2*x**2 - z**2*y**2)
[{x: -y}, {x: y}, {z: 0}]
>>> solve(z**2*x - z**2*y**2)
[{x: y**2}, {z: 0}]
When an object other than a Symbol is given as a symbol, it is
isolated algebraically and an implicit solution may be obtained.
This is mostly provided as a convenience to save you from replacing
the object with a Symbol and solving for that Symbol. It will only
work if the specified object can be replaced with a Symbol using the
subs method:
>>> solve(f(x) - x, f(x))
[x]
>>> solve(f(x).diff(x) - f(x) - x, f(x).diff(x))
[x + f(x)]
>>> solve(f(x).diff(x) - f(x) - x, f(x))
[-x + Derivative(f(x), x)]
>>> solve(x + exp(x)**2, exp(x), set=True)
([exp(x)], {(-sqrt(-x),), (sqrt(-x),)})
>>> from sympy import Indexed, IndexedBase, Tuple, sqrt
>>> A = IndexedBase('A')
>>> eqs = Tuple(A[1] + A[2] - 3, A[1] - A[2] + 1)
>>> solve(eqs, eqs.atoms(Indexed))
{A[1]: 1, A[2]: 2}
* To solve for a symbol implicitly, use implicit=True:
>>> solve(x + exp(x), x)
[-LambertW(1)]
>>> solve(x + exp(x), x, implicit=True)
[-exp(x)]
* It is possible to solve for anything that can be targeted with
subs:
>>> solve(x + 2 + sqrt(3), x + 2)
[-sqrt(3)]
>>> solve((x + 2 + sqrt(3), x + 4 + y), y, x + 2)
{y: -2 + sqrt(3), x + 2: -sqrt(3)}
* Nothing heroic is done in this implicit solving so you may end up
with a symbol still in the solution:
>>> eqs = (x*y + 3*y + sqrt(3), x + 4 + y)
>>> solve(eqs, y, x + 2)
{y: -sqrt(3)/(x + 3), x + 2: -2*x/(x + 3) - 6/(x + 3) + sqrt(3)/(x + 3)}
>>> solve(eqs, y*x, x)
{x: -y - 4, x*y: -3*y - sqrt(3)}
* If you attempt to solve for a number remember that the number
you have obtained does not necessarily mean that the value is
equivalent to the expression obtained:
>>> solve(sqrt(2) - 1, 1)
[sqrt(2)]
>>> solve(x - y + 1, 1) # /!\ -1 is targeted, too
[x/(y - 1)]
>>> [_.subs(z, -1) for _ in solve((x - y + 1).subs(-1, z), 1)]
[-x + y]
* To solve for a function within a derivative, use ``dsolve``.
Single expression and more than one symbol:
* When there is a linear solution:
>>> solve(x - y**2, x, y)
[(y**2, y)]
>>> solve(x**2 - y, x, y)
[(x, x**2)]
>>> solve(x**2 - y, x, y, dict=True)
[{y: x**2}]
* When undetermined coefficients are identified:
* That are linear:
>>> solve((a + b)*x - b + 2, a, b)
{a: -2, b: 2}
* That are nonlinear:
>>> solve((a + b)*x - b**2 + 2, a, b, set=True)
([a, b], {(-sqrt(2), sqrt(2)), (sqrt(2), -sqrt(2))})
* If there is no linear solution, then the first successful
attempt for a nonlinear solution will be returned:
>>> solve(x**2 - y**2, x, y, dict=True)
[{x: -y}, {x: y}]
>>> solve(x**2 - y**2/exp(x), x, y, dict=True)
[{x: 2*LambertW(-y/2)}, {x: 2*LambertW(y/2)}]
>>> solve(x**2 - y**2/exp(x), y, x)
[(-x*sqrt(exp(x)), x), (x*sqrt(exp(x)), x)]
Iterable of one or more of the above:
* Involving relationals or bools:
>>> solve([x < 3, x - 2])
Eq(x, 2)
>>> solve([x > 3, x - 2])
False
* When the system is linear:
* With a solution:
>>> solve([x - 3], x)
{x: 3}
>>> solve((x + 5*y - 2, -3*x + 6*y - 15), x, y)
{x: -3, y: 1}
>>> solve((x + 5*y - 2, -3*x + 6*y - 15), x, y, z)
{x: -3, y: 1}
>>> solve((x + 5*y - 2, -3*x + 6*y - z), z, x, y)
{x: 2 - 5*y, z: 21*y - 6}
* Without a solution:
>>> solve([x + 3, x - 3])
[]
* When the system is not linear:
>>> solve([x**2 + y -2, y**2 - 4], x, y, set=True)
([x, y], {(-2, -2), (0, 2), (2, -2)})
* If no *symbols* are given, all free *symbols* will be selected and a
list of mappings returned:
>>> solve([x - 2, x**2 + y])
[{x: 2, y: -4}]
>>> solve([x - 2, x**2 + f(x)], {f(x), x})
[{x: 2, f(x): -4}]
* If any equation does not depend on the symbol(s) given, it will be
eliminated from the equation set and an answer may be given
implicitly in terms of variables that were not of interest:
>>> solve([x - y, y - 3], x)
{x: y}
**Additional Examples**
``solve()`` with check=True (default) will run through the symbol tags to
elimate unwanted solutions. If no assumptions are included, all possible
solutions will be returned:
>>> from sympy import Symbol, solve
>>> x = Symbol("x")
>>> solve(x**2 - 1)
[-1, 1]
By using the positive tag, only one solution will be returned:
>>> pos = Symbol("pos", positive=True)
>>> solve(pos**2 - 1)
[1]
Assumptions are not checked when ``solve()`` input involves
relationals or bools.
When the solutions are checked, those that make any denominator zero
are automatically excluded. If you do not want to exclude such solutions,
then use the check=False option:
>>> from sympy import sin, limit
>>> solve(sin(x)/x) # 0 is excluded
[pi]
If check=False, then a solution to the numerator being zero is found: x = 0.
In this case, this is a spurious solution since $\sin(x)/x$ has the well
known limit (without dicontinuity) of 1 at x = 0:
>>> solve(sin(x)/x, check=False)
[0, pi]
In the following case, however, the limit exists and is equal to the
value of x = 0 that is excluded when check=True:
>>> eq = x**2*(1/x - z**2/x)
>>> solve(eq, x)
[]
>>> solve(eq, x, check=False)
[0]
>>> limit(eq, x, 0, '-')
0
>>> limit(eq, x, 0, '+')
0
**Disabling High-Order Explicit Solutions**
When solving polynomial expressions, you might not want explicit solutions
(which can be quite long). If the expression is univariate, ``CRootOf``
instances will be returned instead:
>>> solve(x**3 - x + 1)
[-1/((-1/2 - sqrt(3)*I/2)*(3*sqrt(69)/2 + 27/2)**(1/3)) - (-1/2 -
sqrt(3)*I/2)*(3*sqrt(69)/2 + 27/2)**(1/3)/3, -(-1/2 +
sqrt(3)*I/2)*(3*sqrt(69)/2 + 27/2)**(1/3)/3 - 1/((-1/2 +
sqrt(3)*I/2)*(3*sqrt(69)/2 + 27/2)**(1/3)), -(3*sqrt(69)/2 +
27/2)**(1/3)/3 - 1/(3*sqrt(69)/2 + 27/2)**(1/3)]
>>> solve(x**3 - x + 1, cubics=False)
[CRootOf(x**3 - x + 1, 0),
CRootOf(x**3 - x + 1, 1),
CRootOf(x**3 - x + 1, 2)]
If the expression is multivariate, no solution might be returned:
>>> solve(x**3 - x + a, x, cubics=False)
[]
Sometimes solutions will be obtained even when a flag is False because the
expression could be factored. In the following example, the equation can
be factored as the product of a linear and a quadratic factor so explicit
solutions (which did not require solving a cubic expression) are obtained:
>>> eq = x**3 + 3*x**2 + x - 1
>>> solve(eq, cubics=False)
[-1, -1 + sqrt(2), -sqrt(2) - 1]
**Solving Equations Involving Radicals**
Because of SymPy's use of the principle root, some solutions
to radical equations will be missed unless check=False:
>>> from sympy import root
>>> eq = root(x**3 - 3*x**2, 3) + 1 - x
>>> solve(eq)
[]
>>> solve(eq, check=False)
[1/3]
In the above example, there is only a single solution to the
equation. Other expressions will yield spurious roots which
must be checked manually; roots which give a negative argument
to odd-powered radicals will also need special checking:
>>> from sympy import real_root, S
>>> eq = root(x, 3) - root(x, 5) + S(1)/7
>>> solve(eq) # this gives 2 solutions but misses a 3rd
[CRootOf(7*x**5 - 7*x**3 + 1, 1)**15,
CRootOf(7*x**5 - 7*x**3 + 1, 2)**15]
>>> sol = solve(eq, check=False)
>>> [abs(eq.subs(x,i).n(2)) for i in sol]
[0.48, 0.e-110, 0.e-110, 0.052, 0.052]
The first solution is negative so ``real_root`` must be used to see that it
satisfies the expression:
>>> abs(real_root(eq.subs(x, sol[0])).n(2))
0.e-110
If the roots of the equation are not real then more care will be
necessary to find the roots, especially for higher order equations.
Consider the following expression:
>>> expr = root(x, 3) - root(x, 5)
We will construct a known value for this expression at x = 3 by selecting
the 1-th root for each radical:
>>> expr1 = root(x, 3, 1) - root(x, 5, 1)
>>> v = expr1.subs(x, -3)
The ``solve`` function is unable to find any exact roots to this equation:
>>> eq = Eq(expr, v); eq1 = Eq(expr1, v)
>>> solve(eq, check=False), solve(eq1, check=False)
([], [])
The function ``unrad``, however, can be used to get a form of the equation
for which numerical roots can be found:
>>> from sympy.solvers.solvers import unrad
>>> from sympy import nroots
>>> e, (p, cov) = unrad(eq)
>>> pvals = nroots(e)
>>> inversion = solve(cov, x)[0]
>>> xvals = [inversion.subs(p, i) for i in pvals]
Although ``eq`` or ``eq1`` could have been used to find ``xvals``, the
solution can only be verified with ``expr1``:
>>> z = expr - v
>>> [xi.n(chop=1e-9) for xi in xvals if abs(z.subs(x, xi).n()) < 1e-9]
[]
>>> z1 = expr1 - v
>>> [xi.n(chop=1e-9) for xi in xvals if abs(z1.subs(x, xi).n()) < 1e-9]
[-3.0]
Parameters
==========
f :
- a single Expr or Poly that must be zero
- an Equality
- a Relational expression
- a Boolean
- iterable of one or more of the above
symbols : (object(s) to solve for) specified as
- none given (other non-numeric objects will be used)
- single symbol
- denested list of symbols
(e.g., ``solve(f, x, y)``)
- ordered iterable of symbols
(e.g., ``solve(f, [x, y])``)
flags :
dict=True (default is False)
Return list (perhaps empty) of solution mappings.
set=True (default is False)
Return list of symbols and set of tuple(s) of solution(s).
exclude=[] (default)
Do not try to solve for any of the free symbols in exclude;
if expressions are given, the free symbols in them will
be extracted automatically.
check=True (default)
If False, do not do any testing of solutions. This can be
useful if you want to include solutions that make any
denominator zero.
numerical=True (default)
Do a fast numerical check if *f* has only one symbol.
minimal=True (default is False)
A very fast, minimal testing.
warn=True (default is False)
Show a warning if ``checksol()`` could not conclude.
simplify=True (default)
Simplify all but polynomials of order 3 or greater before
returning them and (if check is not False) use the
general simplify function on the solutions and the
expression obtained when they are substituted into the
function which should be zero.
force=True (default is False)
Make positive all symbols without assumptions regarding sign.
rational=True (default)
Recast Floats as Rational; if this option is not used, the
system containing Floats may fail to solve because of issues
with polys. If rational=None, Floats will be recast as
rationals but the answer will be recast as Floats. If the
flag is False then nothing will be done to the Floats.
manual=True (default is False)
Do not use the polys/matrix method to solve a system of
equations, solve them one at a time as you might "manually."
implicit=True (default is False)
Allows ``solve`` to return a solution for a pattern in terms of
other functions that contain that pattern; this is only
needed if the pattern is inside of some invertible function
like cos, exp, ect.
particular=True (default is False)
Instructs ``solve`` to try to find a particular solution to a linear
system with as many zeros as possible; this is very expensive.
quick=True (default is False)
When using particular=True, use a fast heuristic to find a
solution with many zeros (instead of using the very slow method
guaranteed to find the largest number of zeros possible).
cubics=True (default)
Return explicit solutions when cubic expressions are encountered.
quartics=True (default)
Return explicit solutions when quartic expressions are encountered.
quintics=True (default)
Return explicit solutions (if possible) when quintic expressions
are encountered.
See Also
========
rsolve: For solving recurrence relationships
dsolve: For solving differential equations
"""
# keeping track of how f was passed since if it is a list
# a dictionary of results will be returned.
###########################################################################
def _sympified_list(w):
return list(map(sympify, w if iterable(w) else [w]))
bare_f = not iterable(f)
ordered_symbols = (symbols and
symbols[0] and
(isinstance(symbols[0], Symbol) or
is_sequence(symbols[0],
include=GeneratorType)
)
)
f, symbols = (_sympified_list(w) for w in [f, symbols])
if isinstance(f, list):
f = [s for s in f if s is not S.true and s is not True]
implicit = flags.get('implicit', False)
# preprocess symbol(s)
###########################################################################
if not symbols:
# get symbols from equations
symbols = set().union(*[fi.free_symbols for fi in f])
if len(symbols) < len(f):
for fi in f:
pot = preorder_traversal(fi)
for p in pot:
if isinstance(p, AppliedUndef):
flags['dict'] = True # better show symbols
symbols.add(p)
pot.skip() # don't go any deeper
symbols = list(symbols)
ordered_symbols = False
elif len(symbols) == 1 and iterable(symbols[0]):
symbols = symbols[0]
# remove symbols the user is not interested in
exclude = flags.pop('exclude', set())
if exclude:
if isinstance(exclude, Expr):
exclude = [exclude]
exclude = set().union(*[e.free_symbols for e in sympify(exclude)])
symbols = [s for s in symbols if s not in exclude]
# preprocess equation(s)
###########################################################################
for i, fi in enumerate(f):
if isinstance(fi, (Equality, Unequality)):
if 'ImmutableDenseMatrix' in [type(a).__name__ for a in fi.args]:
fi = fi.lhs - fi.rhs
else:
L, R = fi.args
if isinstance(R, BooleanAtom):
L, R = R, L
if isinstance(L, BooleanAtom):
if isinstance(fi, Unequality):
L = ~L
if R.is_Relational:
fi = ~R if L is S.false else R
elif R.is_Symbol:
return L
elif R.is_Boolean and (~R).is_Symbol:
return ~L
else:
raise NotImplementedError(filldedent('''
Unanticipated argument of Eq when other arg
is True or False.
'''))
else:
fi = fi.rewrite(Add, evaluate=False)
f[i] = fi
if fi.is_Relational:
return reduce_inequalities(f, symbols=symbols)
if isinstance(fi, Poly):
f[i] = fi.as_expr()
# rewrite hyperbolics in terms of exp
f[i] = f[i].replace(lambda w: isinstance(w, HyperbolicFunction) and \
(len(w.free_symbols & set(symbols)) > 0), lambda w: w.rewrite(exp))
# if we have a Matrix, we need to iterate over its elements again
if f[i].is_Matrix:
bare_f = False
f.extend(list(f[i]))
f[i] = S.Zero
# if we can split it into real and imaginary parts then do so
freei = f[i].free_symbols
if freei and all(s.is_extended_real or s.is_imaginary for s in freei):
fr, fi = f[i].as_real_imag()
# accept as long as new re, im, arg or atan2 are not introduced
had = f[i].atoms(re, im, arg, atan2)
if fr and fi and fr != fi and not any(
i.atoms(re, im, arg, atan2) - had for i in (fr, fi)):
if bare_f:
bare_f = False
f[i: i + 1] = [fr, fi]
# real/imag handling -----------------------------
if any(isinstance(fi, (bool, BooleanAtom)) for fi in f):
if flags.get('set', False):
return [], set()
return []
for i, fi in enumerate(f):
# Abs
while True:
was = fi
fi = fi.replace(Abs, lambda arg:
separatevars(Abs(arg)).rewrite(Piecewise) if arg.has(*symbols)
else Abs(arg))
if was == fi:
break
for e in fi.find(Abs):
if e.has(*symbols):
raise NotImplementedError('solving %s when the argument '
'is not real or imaginary.' % e)
# arg
fi = fi.replace(arg, lambda a: arg(a).rewrite(atan2).rewrite(atan))
# save changes
f[i] = fi
# see if re(s) or im(s) appear
freim = [fi for fi in f if fi.has(re, im)]
if freim:
irf = []
for s in symbols:
if s.is_real or s.is_imaginary:
continue # neither re(x) nor im(x) will appear
# if re(s) or im(s) appear, the auxiliary equation must be present
if any(fi.has(re(s), im(s)) for fi in freim):
irf.append((s, re(s) + S.ImaginaryUnit*im(s)))
if irf:
for s, rhs in irf:
for i, fi in enumerate(f):
f[i] = fi.xreplace({s: rhs})
f.append(s - rhs)
symbols.extend([re(s), im(s)])
if bare_f:
bare_f = False
flags['dict'] = True
# end of real/imag handling -----------------------------
symbols = list(uniq(symbols))
if not ordered_symbols:
# we do this to make the results returned canonical in case f
# contains a system of nonlinear equations; all other cases should
# be unambiguous
symbols = sorted(symbols, key=default_sort_key)
# we can solve for non-symbol entities by replacing them with Dummy symbols
f, symbols, swap_sym = recast_to_symbols(f, symbols)
# this is needed in the next two events
symset = set(symbols)
# get rid of equations that have no symbols of interest; we don't
# try to solve them because the user didn't ask and they might be
# hard to solve; this means that solutions may be given in terms
# of the eliminated equations e.g. solve((x-y, y-3), x) -> {x: y}
newf = []
for fi in f:
# let the solver handle equations that..
# - have no symbols but are expressions
# - have symbols of interest
# - have no symbols of interest but are constant
# but when an expression is not constant and has no symbols of
# interest, it can't change what we obtain for a solution from
# the remaining equations so we don't include it; and if it's
# zero it can be removed and if it's not zero, there is no
# solution for the equation set as a whole
#
# The reason for doing this filtering is to allow an answer
# to be obtained to queries like solve((x - y, y), x); without
# this mod the return value is []
ok = False
if fi.free_symbols & symset:
ok = True
else:
if fi.is_number:
if fi.is_Number:
if fi.is_zero:
continue
return []
ok = True
else:
if fi.is_constant():
ok = True
if ok:
newf.append(fi)
if not newf:
return []
f = newf
del newf
# mask off any Object that we aren't going to invert: Derivative,
# Integral, etc... so that solving for anything that they contain will
# give an implicit solution
seen = set()
non_inverts = set()
for fi in f:
pot = preorder_traversal(fi)
for p in pot:
if not isinstance(p, Expr) or isinstance(p, Piecewise):
pass
elif (isinstance(p, bool) or
not p.args or
p in symset or
p.is_Add or p.is_Mul or
p.is_Pow and not implicit or
p.is_Function and not implicit) and p.func not in (re, im):
continue
elif not p in seen:
seen.add(p)
if p.free_symbols & symset:
non_inverts.add(p)
else:
continue
pot.skip()
del seen
non_inverts = dict(list(zip(non_inverts, [Dummy() for _ in non_inverts])))
f = [fi.subs(non_inverts) for fi in f]
# Both xreplace and subs are needed below: xreplace to force substitution
# inside Derivative, subs to handle non-straightforward substitutions
non_inverts = [(v, k.xreplace(swap_sym).subs(swap_sym)) for k, v in non_inverts.items()]
# rationalize Floats
floats = False
if flags.get('rational', True) is not False:
for i, fi in enumerate(f):
if fi.has(Float):
floats = True
f[i] = nsimplify(fi, rational=True)
# capture any denominators before rewriting since
# they may disappear after the rewrite, e.g. issue 14779
flags['_denominators'] = _simple_dens(f[0], symbols)
# Any embedded piecewise functions need to be brought out to the
# top level so that the appropriate strategy gets selected.
# However, this is necessary only if one of the piecewise
# functions depends on one of the symbols we are solving for.
def _has_piecewise(e):
if e.is_Piecewise:
return e.has(*symbols)
return any([_has_piecewise(a) for a in e.args])
for i, fi in enumerate(f):
if _has_piecewise(fi):
f[i] = piecewise_fold(fi)
#
# try to get a solution
###########################################################################
if bare_f:
solution = _solve(f[0], *symbols, **flags)
else:
solution = _solve_system(f, symbols, **flags)
#
# postprocessing
###########################################################################
# Restore masked-off objects
if non_inverts:
def _do_dict(solution):
return {k: v.subs(non_inverts) for k, v in
solution.items()}
for i in range(1):
if isinstance(solution, dict):
solution = _do_dict(solution)
break
elif solution and isinstance(solution, list):
if isinstance(solution[0], dict):
solution = [_do_dict(s) for s in solution]
break
elif isinstance(solution[0], tuple):
solution = [tuple([v.subs(non_inverts) for v in s]) for s
in solution]
break
else:
solution = [v.subs(non_inverts) for v in solution]
break
elif not solution:
break
else:
raise NotImplementedError(filldedent('''
no handling of %s was implemented''' % solution))
# Restore original "symbols" if a dictionary is returned.
# This is not necessary for
# - the single univariate equation case
# since the symbol will have been removed from the solution;
# - the nonlinear poly_system since that only supports zero-dimensional
# systems and those results come back as a list
#
# ** unless there were Derivatives with the symbols, but those were handled
# above.
if swap_sym:
symbols = [swap_sym.get(k, k) for k in symbols]
if isinstance(solution, dict):
solution = {swap_sym.get(k, k): v.subs(swap_sym)
for k, v in solution.items()}
elif solution and isinstance(solution, list) and isinstance(solution[0], dict):
for i, sol in enumerate(solution):
solution[i] = {swap_sym.get(k, k): v.subs(swap_sym)
for k, v in sol.items()}
# undo the dictionary solutions returned when the system was only partially
# solved with poly-system if all symbols are present
if (
not flags.get('dict', False) and
solution and
ordered_symbols and
not isinstance(solution, dict) and
all(isinstance(sol, dict) for sol in solution)
):
solution = [tuple([r.get(s, s) for s in symbols]) for r in solution]
# Get assumptions about symbols, to filter solutions.
# Note that if assumptions about a solution can't be verified, it is still
# returned.
check = flags.get('check', True)
# restore floats
if floats and solution and flags.get('rational', None) is None:
solution = nfloat(solution, exponent=False)
if check and solution: # assumption checking
warn = flags.get('warn', False)
got_None = [] # solutions for which one or more symbols gave None
no_False = [] # solutions for which no symbols gave False
if isinstance(solution, tuple):
# this has already been checked and is in as_set form
return solution
elif isinstance(solution, list):
if isinstance(solution[0], tuple):
for sol in solution:
for symb, val in zip(symbols, sol):
test = check_assumptions(val, **symb.assumptions0)
if test is False:
break
if test is None:
got_None.append(sol)
else:
no_False.append(sol)
elif isinstance(solution[0], dict):
for sol in solution:
a_None = False
for symb, val in sol.items():
test = check_assumptions(val, **symb.assumptions0)
if test:
continue
if test is False:
break
a_None = True
else:
no_False.append(sol)
if a_None:
got_None.append(sol)
else: # list of expressions
for sol in solution:
test = check_assumptions(sol, **symbols[0].assumptions0)
if test is False:
continue
no_False.append(sol)
if test is None:
got_None.append(sol)
elif isinstance(solution, dict):
a_None = False
for symb, val in solution.items():
test = check_assumptions(val, **symb.assumptions0)
if test:
continue
if test is False:
no_False = None
break
a_None = True
else:
no_False = solution
if a_None:
got_None.append(solution)
elif isinstance(solution, (Relational, And, Or)):
if len(symbols) != 1:
raise ValueError("Length should be 1")
if warn and symbols[0].assumptions0:
warnings.warn(filldedent("""
\tWarning: assumptions about variable '%s' are
not handled currently.""" % symbols[0]))
# TODO: check also variable assumptions for inequalities
else:
raise TypeError('Unrecognized solution') # improve the checker
solution = no_False
if warn and got_None:
warnings.warn(filldedent("""
\tWarning: assumptions concerning following solution(s)
can't be checked:""" + '\n\t' +
', '.join(str(s) for s in got_None)))
#
# done
###########################################################################
as_dict = flags.get('dict', False)
as_set = flags.get('set', False)
if not as_set and isinstance(solution, list):
# Make sure that a list of solutions is ordered in a canonical way.
solution.sort(key=default_sort_key)
if not as_dict and not as_set:
return solution or []
# return a list of mappings or []
if not solution:
solution = []
else:
if isinstance(solution, dict):
solution = [solution]
elif iterable(solution[0]):
solution = [dict(list(zip(symbols, s))) for s in solution]
elif isinstance(solution[0], dict):
pass
else:
if len(symbols) != 1:
raise ValueError("Length should be 1")
solution = [{symbols[0]: s} for s in solution]
if as_dict:
return solution
assert as_set
if not solution:
return [], set()
k = list(ordered(solution[0].keys()))
return k, {tuple([s[ki] for ki in k]) for s in solution}
def _solve(f, *symbols, **flags):
"""
Return a checked solution for *f* in terms of one or more of the
symbols. A list should be returned except for the case when a linear
undetermined-coefficients equation is encountered (in which case
a dictionary is returned).
If no method is implemented to solve the equation, a NotImplementedError
will be raised. In the case that conversion of an expression to a Poly
gives None a ValueError will be raised.
"""
not_impl_msg = "No algorithms are implemented to solve equation %s"
if len(symbols) != 1:
soln = None
free = f.free_symbols
ex = free - set(symbols)
if len(ex) != 1:
ind, dep = f.as_independent(*symbols)
ex = ind.free_symbols & dep.free_symbols
if len(ex) == 1:
ex = ex.pop()
try:
# soln may come back as dict, list of dicts or tuples, or
# tuple of symbol list and set of solution tuples
soln = solve_undetermined_coeffs(f, symbols, ex, **flags)
except NotImplementedError:
pass
if soln:
if flags.get('simplify', True):
if isinstance(soln, dict):
for k in soln:
soln[k] = simplify(soln[k])
elif isinstance(soln, list):
if isinstance(soln[0], dict):
for d in soln:
for k in d:
d[k] = simplify(d[k])
elif isinstance(soln[0], tuple):
soln = [tuple(simplify(i) for i in j) for j in soln]
else:
raise TypeError('unrecognized args in list')
elif isinstance(soln, tuple):
sym, sols = soln
soln = sym, {tuple(simplify(i) for i in j) for j in sols}
else:
raise TypeError('unrecognized solution type')
return soln
# find first successful solution
failed = []
got_s = set()
result = []
for s in symbols:
xi, v = solve_linear(f, symbols=[s])
if xi == s:
# no need to check but we should simplify if desired
if flags.get('simplify', True):
v = simplify(v)
vfree = v.free_symbols
if got_s and any([ss in vfree for ss in got_s]):
# sol depends on previously solved symbols: discard it
continue
got_s.add(xi)
result.append({xi: v})
elif xi: # there might be a non-linear solution if xi is not 0
failed.append(s)
if not failed:
return result
for s in failed:
try:
soln = _solve(f, s, **flags)
for sol in soln:
if got_s and any([ss in sol.free_symbols for ss in got_s]):
# sol depends on previously solved symbols: discard it
continue
got_s.add(s)
result.append({s: sol})
except NotImplementedError:
continue
if got_s:
return result
else:
raise NotImplementedError(not_impl_msg % f)
symbol = symbols[0]
#expand binomials only if it has the unknown symbol
f = f.replace(lambda e: isinstance(e, binomial) and e.has(symbol),
lambda e: expand_func(e))
# /!\ capture this flag then set it to False so that no checking in
# recursive calls will be done; only the final answer is checked
flags['check'] = checkdens = check = flags.pop('check', True)
# build up solutions if f is a Mul
if f.is_Mul:
result = set()
for m in f.args:
if m in {S.NegativeInfinity, S.ComplexInfinity, S.Infinity}:
result = set()
break
soln = _solve(m, symbol, **flags)
result.update(set(soln))
result = list(result)
if check:
# all solutions have been checked but now we must
# check that the solutions do not set denominators
# in any factor to zero
dens = flags.get('_denominators', _simple_dens(f, symbols))
result = [s for s in result if
all(not checksol(den, {symbol: s}, **flags) for den in
dens)]
# set flags for quick exit at end; solutions for each
# factor were already checked and simplified
check = False
flags['simplify'] = False
elif f.is_Piecewise:
result = set()
for i, (expr, cond) in enumerate(f.args):
if expr.is_zero:
raise NotImplementedError(
'solve cannot represent interval solutions')
candidates = _solve(expr, symbol, **flags)
# the explicit condition for this expr is the current cond
# and none of the previous conditions
args = [~c for _, c in f.args[:i]] + [cond]
cond = And(*args)
for candidate in candidates:
if candidate in result:
# an unconditional value was already there
continue
try:
v = cond.subs(symbol, candidate)
_eval_simplify = getattr(v, '_eval_simplify', None)
if _eval_simplify is not None:
# unconditionally take the simpification of v
v = _eval_simplify(ratio=2, measure=lambda x: 1)
except TypeError:
# incompatible type with condition(s)
continue
if v == False:
continue
if v == True:
result.add(candidate)
else:
result.add(Piecewise(
(candidate, v),
(S.NaN, True)))
# set flags for quick exit at end; solutions for each
# piece were already checked and simplified
check = False
flags['simplify'] = False
else:
# first see if it really depends on symbol and whether there
# is only a linear solution
f_num, sol = solve_linear(f, symbols=symbols)
if f_num.is_zero or sol is S.NaN:
return []
elif f_num.is_Symbol:
# no need to check but simplify if desired
if flags.get('simplify', True):
sol = simplify(sol)
return [sol]
poly = None
# check for a single non-symbol generator
dums = f_num.atoms(Dummy)
D = f_num.replace(
lambda i: isinstance(i, Add) and symbol in i.free_symbols,
lambda i: Dummy())
if not D.is_Dummy:
dgen = D.atoms(Dummy) - dums
if len(dgen) == 1:
d = dgen.pop()
w = Wild('g')
gen = f_num.match(D.xreplace({d: w}))[w]
spart = gen.as_independent(symbol)[1].as_base_exp()[0]
if spart == symbol:
try:
poly = Poly(f_num, spart)
except PolynomialError:
pass
result = False # no solution was obtained
msg = '' # there is no failure message
# Poly is generally robust enough to convert anything to
# a polynomial and tell us the different generators that it
# contains, so we will inspect the generators identified by
# polys to figure out what to do.
# try to identify a single generator that will allow us to solve this
# as a polynomial, followed (perhaps) by a change of variables if the
# generator is not a symbol
try:
if poly is None:
poly = Poly(f_num)
if poly is None:
raise ValueError('could not convert %s to Poly' % f_num)
except GeneratorsNeeded:
simplified_f = simplify(f_num)
if simplified_f != f_num:
return _solve(simplified_f, symbol, **flags)
raise ValueError('expression appears to be a constant')
gens = [g for g in poly.gens if g.has(symbol)]
def _as_base_q(x):
"""Return (b**e, q) for x = b**(p*e/q) where p/q is the leading
Rational of the exponent of x, e.g. exp(-2*x/3) -> (exp(x), 3)
"""
b, e = x.as_base_exp()
if e.is_Rational:
return b, e.q
if not e.is_Mul:
return x, 1
c, ee = e.as_coeff_Mul()
if c.is_Rational and c is not S.One: # c could be a Float
return b**ee, c.q
return x, 1
if len(gens) > 1:
# If there is more than one generator, it could be that the
# generators have the same base but different powers, e.g.
# >>> Poly(exp(x) + 1/exp(x))
# Poly(exp(-x) + exp(x), exp(-x), exp(x), domain='ZZ')
#
# If unrad was not disabled then there should be no rational
# exponents appearing as in
# >>> Poly(sqrt(x) + sqrt(sqrt(x)))
# Poly(sqrt(x) + x**(1/4), sqrt(x), x**(1/4), domain='ZZ')
bases, qs = list(zip(*[_as_base_q(g) for g in gens]))
bases = set(bases)
if len(bases) > 1 or not all(q == 1 for q in qs):
funcs = {b for b in bases if b.is_Function}
trig = {_ for _ in funcs if
isinstance(_, TrigonometricFunction)}
other = funcs - trig
if not other and len(funcs.intersection(trig)) > 1:
newf = None
if f_num.is_Add and len(f_num.args) == 2:
# check for sin(x)**p = cos(x)**p
_args = f_num.args
t = a, b = [i.atoms(Function).intersection(
trig) for i in _args]
if all(len(i) == 1 for i in t):
a, b = [i.pop() for i in t]
if isinstance(a, cos):
a, b = b, a
_args = _args[::-1]
if isinstance(a, sin) and isinstance(b, cos
) and a.args[0] == b.args[0]:
# sin(x) + cos(x) = 0 -> tan(x) + 1 = 0
newf, _d = (TR2i(_args[0]/_args[1]) + 1
).as_numer_denom()
if not _d.is_Number:
newf = None
if newf is None:
newf = TR1(f_num).rewrite(tan)
if newf != f_num:
# don't check the rewritten form --check
# solutions in the un-rewritten form below
flags['check'] = False
result = _solve(newf, symbol, **flags)
flags['check'] = check
# just a simple case - see if replacement of single function
# clears all symbol-dependent functions, e.g.
# log(x) - log(log(x) - 1) - 3 can be solved even though it has
# two generators.
if result is False and funcs:
funcs = list(ordered(funcs)) # put shallowest function first
f1 = funcs[0]
t = Dummy('t')
# perform the substitution
ftry = f_num.subs(f1, t)
# if no Functions left, we can proceed with usual solve
if not ftry.has(symbol):
cv_sols = _solve(ftry, t, **flags)
cv_inv = _solve(t - f1, symbol, **flags)[0]
sols = list()
for sol in cv_sols:
sols.append(cv_inv.subs(t, sol))
result = list(ordered(sols))
if result is False:
msg = 'multiple generators %s' % gens
else:
# e.g. case where gens are exp(x), exp(-x)
u = bases.pop()
t = Dummy('t')
inv = _solve(u - t, symbol, **flags)
if isinstance(u, (Pow, exp)):
# this will be resolved by factor in _tsolve but we might
# as well try a simple expansion here to get things in
# order so something like the following will work now without
# having to factor:
#
# >>> eq = (exp(I*(-x-2))+exp(I*(x+2)))
# >>> eq.subs(exp(x),y) # fails
# exp(I*(-x - 2)) + exp(I*(x + 2))
# >>> eq.expand().subs(exp(x),y) # works
# y**I*exp(2*I) + y**(-I)*exp(-2*I)
def _expand(p):
b, e = p.as_base_exp()
e = expand_mul(e)
return expand_power_exp(b**e)
ftry = f_num.replace(
lambda w: w.is_Pow or isinstance(w, exp),
_expand).subs(u, t)
if not ftry.has(symbol):
soln = _solve(ftry, t, **flags)
sols = list()
for sol in soln:
for i in inv:
sols.append(i.subs(t, sol))
result = list(ordered(sols))
elif len(gens) == 1:
# There is only one generator that we are interested in, but
# there may have been more than one generator identified by
# polys (e.g. for symbols other than the one we are interested
# in) so recast the poly in terms of our generator of interest.
# Also use composite=True with f_num since Poly won't update
# poly as documented in issue 8810.
poly = Poly(f_num, gens[0], composite=True)
# if we aren't on the tsolve-pass, use roots
if not flags.pop('tsolve', False):
soln = None
deg = poly.degree()
flags['tsolve'] = True
solvers = {k: flags.get(k, True) for k in
('cubics', 'quartics', 'quintics')}
soln = roots(poly, **solvers)
if sum(soln.values()) < deg:
# e.g. roots(32*x**5 + 400*x**4 + 2032*x**3 +
# 5000*x**2 + 6250*x + 3189) -> {}
# so all_roots is used and RootOf instances are
# returned *unless* the system is multivariate
# or high-order EX domain.
try:
soln = poly.all_roots()
except NotImplementedError:
if not flags.get('incomplete', True):
raise NotImplementedError(
filldedent('''
Neither high-order multivariate polynomials
nor sorting of EX-domain polynomials is supported.
If you want to see any results, pass keyword incomplete=True to
solve; to see numerical values of roots
for univariate expressions, use nroots.
'''))
else:
pass
else:
soln = list(soln.keys())
if soln is not None:
u = poly.gen
if u != symbol:
try:
t = Dummy('t')
iv = _solve(u - t, symbol, **flags)
soln = list(ordered({i.subs(t, s) for i in iv for s in soln}))
except NotImplementedError:
# perhaps _tsolve can handle f_num
soln = None
else:
check = False # only dens need to be checked
if soln is not None:
if len(soln) > 2:
# if the flag wasn't set then unset it since high-order
# results are quite long. Perhaps one could base this
# decision on a certain critical length of the
# roots. In addition, wester test M2 has an expression
# whose roots can be shown to be real with the
# unsimplified form of the solution whereas only one of
# the simplified forms appears to be real.
flags['simplify'] = flags.get('simplify', False)
result = soln
# fallback if above fails
# -----------------------
if result is False:
# try unrad
if flags.pop('_unrad', True):
try:
u = unrad(f_num, symbol)
except (ValueError, NotImplementedError):
u = False
if u:
eq, cov = u
if cov:
isym, ieq = cov
inv = _solve(ieq, symbol, **flags)[0]
rv = {inv.subs(isym, xi) for xi in _solve(eq, isym, **flags)}
else:
try:
rv = set(_solve(eq, symbol, **flags))
except NotImplementedError:
rv = None
if rv is not None:
result = list(ordered(rv))
# if the flag wasn't set then unset it since unrad results
# can be quite long or of very high order
flags['simplify'] = flags.get('simplify', False)
else:
pass # for coverage
# try _tsolve
if result is False:
flags.pop('tsolve', None) # allow tsolve to be used on next pass
try:
soln = _tsolve(f_num, symbol, **flags)
if soln is not None:
result = soln
except PolynomialError:
pass
# ----------- end of fallback ----------------------------
if result is False:
raise NotImplementedError('\n'.join([msg, not_impl_msg % f]))
if flags.get('simplify', True):
result = list(map(simplify, result))
# we just simplified the solution so we now set the flag to
# False so the simplification doesn't happen again in checksol()
flags['simplify'] = False
if checkdens:
# reject any result that makes any denom. affirmatively 0;
# if in doubt, keep it
dens = _simple_dens(f, symbols)
result = [s for s in result if
all(not checksol(d, {symbol: s}, **flags)
for d in dens)]
if check:
# keep only results if the check is not False
result = [r for r in result if
checksol(f_num, {symbol: r}, **flags) is not False]
return result
def _solve_system(exprs, symbols, **flags):
if not exprs:
return []
if flags.pop('_split', True):
# Split the system into connected components
V = exprs
symsset = set(symbols)
exprsyms = {e: e.free_symbols & symsset for e in exprs}
E = []
sym_indices = {sym: i for i, sym in enumerate(symbols)}
for n, e1 in enumerate(exprs):
for e2 in exprs[:n]:
# Equations are connected if they share a symbol
if exprsyms[e1] & exprsyms[e2]:
E.append((e1, e2))
G = V, E
subexprs = connected_components(G)
if len(subexprs) > 1:
subsols = []
for subexpr in subexprs:
subsyms = set()
for e in subexpr:
subsyms |= exprsyms[e]
subsyms = list(sorted(subsyms, key = lambda x: sym_indices[x]))
# use canonical subset to solve these equations
# since there may be redundant equations in the set:
# take the first equation of several that may have the
# same sub-maximal free symbols of interest; the
# other equations that weren't used should be checked
# to see that they did not fail -- does the solver
# take care of that?
choices = sift(subexpr, lambda x: tuple(ordered(exprsyms[x])))
subexpr = choices.pop(tuple(ordered(subsyms)), [])
for k in choices:
subexpr.append(next(ordered(choices[k])))
flags['_split'] = False # skip split step
subsol = _solve_system(subexpr, subsyms, **flags)
if not isinstance(subsol, list):
subsol = [subsol]
subsols.append(subsol)
# Full solution is cartesion product of subsystems
sols = []
for soldicts in cartes(*subsols):
sols.append(dict(item for sd in soldicts
for item in sd.items()))
# Return a list with one dict as just the dict
if len(sols) == 1:
return sols[0]
return sols
polys = []
dens = set()
failed = []
result = False
linear = False
manual = flags.get('manual', False)
checkdens = check = flags.get('check', True)
for j, g in enumerate(exprs):
dens.update(_simple_dens(g, symbols))
i, d = _invert(g, *symbols)
g = d - i
g = g.as_numer_denom()[0]
if manual:
failed.append(g)
continue
poly = g.as_poly(*symbols, extension=True)
if poly is not None:
polys.append(poly)
else:
failed.append(g)
if not polys:
solved_syms = []
else:
if all(p.is_linear for p in polys):
n, m = len(polys), len(symbols)
matrix = zeros(n, m + 1)
for i, poly in enumerate(polys):
for monom, coeff in poly.terms():
try:
j = monom.index(1)
matrix[i, j] = coeff
except ValueError:
matrix[i, m] = -coeff
# returns a dictionary ({symbols: values}) or None
if flags.pop('particular', False):
result = minsolve_linear_system(matrix, *symbols, **flags)
else:
result = solve_linear_system(matrix, *symbols, **flags)
if failed:
if result:
solved_syms = list(result.keys())
else:
solved_syms = []
else:
linear = True
else:
if len(symbols) > len(polys):
from sympy.utilities.iterables import subsets
free = set().union(*[p.free_symbols for p in polys])
free = list(ordered(free.intersection(symbols)))
got_s = set()
result = []
for syms in subsets(free, len(polys)):
try:
# returns [] or list of tuples of solutions for syms
res = solve_poly_system(polys, *syms)
if res:
for r in res:
skip = False
for r1 in r:
if got_s and any([ss in r1.free_symbols
for ss in got_s]):
# sol depends on previously
# solved symbols: discard it
skip = True
if not skip:
got_s.update(syms)
result.extend([dict(list(zip(syms, r)))])
except NotImplementedError:
pass
if got_s:
solved_syms = list(got_s)
else:
raise NotImplementedError('no valid subset found')
else:
try:
result = solve_poly_system(polys, *symbols)
if result:
solved_syms = symbols
# we don't know here if the symbols provided
# were given or not, so let solve resolve that.
# A list of dictionaries is going to always be
# returned from here.
result = [dict(list(zip(solved_syms, r))) for r in result]
except NotImplementedError:
failed.extend([g.as_expr() for g in polys])
solved_syms = []
result = None
if result:
if isinstance(result, dict):
result = [result]
else:
result = [{}]
if failed:
# For each failed equation, see if we can solve for one of the
# remaining symbols from that equation. If so, we update the
# solution set and continue with the next failed equation,
# repeating until we are done or we get an equation that can't
# be solved.
def _ok_syms(e, sort=False):
rv = (e.free_symbols - solved_syms) & legal
if sort:
rv = list(rv)
rv.sort(key=default_sort_key)
return rv
solved_syms = set(solved_syms) # set of symbols we have solved for
legal = set(symbols) # what we are interested in
# sort so equation with the fewest potential symbols is first
u = Dummy() # used in solution checking
for eq in ordered(failed, lambda _: len(_ok_syms(_))):
newresult = []
bad_results = []
got_s = set()
hit = False
for r in result:
# update eq with everything that is known so far
eq2 = eq.subs(r)
# if check is True then we see if it satisfies this
# equation, otherwise we just accept it
if check and r:
b = checksol(u, u, eq2, minimal=True)
if b is not None:
# this solution is sufficient to know whether
# it is valid or not so we either accept or
# reject it, then continue
if b:
newresult.append(r)
else:
bad_results.append(r)
continue
# search for a symbol amongst those available that
# can be solved for
ok_syms = _ok_syms(eq2, sort=True)
if not ok_syms:
if r:
newresult.append(r)
break # skip as it's independent of desired symbols
for s in ok_syms:
try:
soln = _solve(eq2, s, **flags)
except NotImplementedError:
continue
# put each solution in r and append the now-expanded
# result in the new result list; use copy since the
# solution for s in being added in-place
for sol in soln:
if got_s and any([ss in sol.free_symbols for ss in got_s]):
# sol depends on previously solved symbols: discard it
continue
rnew = r.copy()
for k, v in r.items():
rnew[k] = v.subs(s, sol)
# and add this new solution
rnew[s] = sol
newresult.append(rnew)
hit = True
got_s.add(s)
if not hit:
raise NotImplementedError('could not solve %s' % eq2)
else:
result = newresult
for b in bad_results:
if b in result:
result.remove(b)
default_simplify = bool(failed) # rely on system-solvers to simplify
if flags.get('simplify', default_simplify):
for r in result:
for k in r:
r[k] = simplify(r[k])
flags['simplify'] = False # don't need to do so in checksol now
if checkdens:
result = [r for r in result
if not any(checksol(d, r, **flags) for d in dens)]
if check and not linear:
result = [r for r in result
if not any(checksol(e, r, **flags) is False for e in exprs)]
result = [r for r in result if r]
if linear and result:
result = result[0]
return result
def solve_linear(lhs, rhs=0, symbols=[], exclude=[]):
r"""
Return a tuple derived from ``f = lhs - rhs`` that is one of
the following: ``(0, 1)``, ``(0, 0)``, ``(symbol, solution)``, ``(n, d)``.
Explanation
===========
``(0, 1)`` meaning that ``f`` is independent of the symbols in *symbols*
that are not in *exclude*.
``(0, 0)`` meaning that there is no solution to the equation amongst the
symbols given. If the first element of the tuple is not zero, then the
function is guaranteed to be dependent on a symbol in *symbols*.
``(symbol, solution)`` where symbol appears linearly in the numerator of
``f``, is in *symbols* (if given), and is not in *exclude* (if given). No
simplification is done to ``f`` other than a ``mul=True`` expansion, so the
solution will correspond strictly to a unique solution.
``(n, d)`` where ``n`` and ``d`` are the numerator and denominator of ``f``
when the numerator was not linear in any symbol of interest; ``n`` will
never be a symbol unless a solution for that symbol was found (in which case
the second element is the solution, not the denominator).
Examples
========
>>> from sympy.core.power import Pow
>>> from sympy.polys.polytools import cancel
``f`` is independent of the symbols in *symbols* that are not in
*exclude*:
>>> from sympy.solvers.solvers import solve_linear
>>> from sympy.abc import x, y, z
>>> from sympy import cos, sin
>>> eq = y*cos(x)**2 + y*sin(x)**2 - y # = y*(1 - 1) = 0
>>> solve_linear(eq)
(0, 1)
>>> eq = cos(x)**2 + sin(x)**2 # = 1
>>> solve_linear(eq)
(0, 1)
>>> solve_linear(x, exclude=[x])
(0, 1)
The variable ``x`` appears as a linear variable in each of the
following:
>>> solve_linear(x + y**2)
(x, -y**2)
>>> solve_linear(1/x - y**2)
(x, y**(-2))
When not linear in ``x`` or ``y`` then the numerator and denominator are
returned:
>>> solve_linear(x**2/y**2 - 3)
(x**2 - 3*y**2, y**2)
If the numerator of the expression is a symbol, then ``(0, 0)`` is
returned if the solution for that symbol would have set any
denominator to 0:
>>> eq = 1/(1/x - 2)
>>> eq.as_numer_denom()
(x, 1 - 2*x)
>>> solve_linear(eq)
(0, 0)
But automatic rewriting may cause a symbol in the denominator to
appear in the numerator so a solution will be returned:
>>> (1/x)**-1
x
>>> solve_linear((1/x)**-1)
(x, 0)
Use an unevaluated expression to avoid this:
>>> solve_linear(Pow(1/x, -1, evaluate=False))
(0, 0)
If ``x`` is allowed to cancel in the following expression, then it
appears to be linear in ``x``, but this sort of cancellation is not
done by ``solve_linear`` so the solution will always satisfy the
original expression without causing a division by zero error.
>>> eq = x**2*(1/x - z**2/x)
>>> solve_linear(cancel(eq))
(x, 0)
>>> solve_linear(eq)
(x**2*(1 - z**2), x)
A list of symbols for which a solution is desired may be given:
>>> solve_linear(x + y + z, symbols=[y])
(y, -x - z)
A list of symbols to ignore may also be given:
>>> solve_linear(x + y + z, exclude=[x])
(y, -x - z)
(A solution for ``y`` is obtained because it is the first variable
from the canonically sorted list of symbols that had a linear
solution.)
"""
if isinstance(lhs, Equality):
if rhs:
raise ValueError(filldedent('''
If lhs is an Equality, rhs must be 0 but was %s''' % rhs))
rhs = lhs.rhs
lhs = lhs.lhs
dens = None
eq = lhs - rhs
n, d = eq.as_numer_denom()
if not n:
return S.Zero, S.One
free = n.free_symbols
if not symbols:
symbols = free
else:
bad = [s for s in symbols if not s.is_Symbol]
if bad:
if len(bad) == 1:
bad = bad[0]
if len(symbols) == 1:
eg = 'solve(%s, %s)' % (eq, symbols[0])
else:
eg = 'solve(%s, *%s)' % (eq, list(symbols))
raise ValueError(filldedent('''
solve_linear only handles symbols, not %s. To isolate
non-symbols use solve, e.g. >>> %s <<<.
''' % (bad, eg)))
symbols = free.intersection(symbols)
symbols = symbols.difference(exclude)
if not symbols:
return S.Zero, S.One
# derivatives are easy to do but tricky to analyze to see if they
# are going to disallow a linear solution, so for simplicity we
# just evaluate the ones that have the symbols of interest
derivs = defaultdict(list)
for der in n.atoms(Derivative):
csym = der.free_symbols & symbols
for c in csym:
derivs[c].append(der)
all_zero = True
for xi in sorted(symbols, key=default_sort_key): # canonical order
# if there are derivatives in this var, calculate them now
if isinstance(derivs[xi], list):
derivs[xi] = {der: der.doit() for der in derivs[xi]}
newn = n.subs(derivs[xi])
dnewn_dxi = newn.diff(xi)
# dnewn_dxi can be nonzero if it survives differentation by any
# of its free symbols
free = dnewn_dxi.free_symbols
if dnewn_dxi and (not free or any(dnewn_dxi.diff(s) for s in free)):
all_zero = False
if dnewn_dxi is S.NaN:
break
if xi not in dnewn_dxi.free_symbols:
vi = -1/dnewn_dxi*(newn.subs(xi, 0))
if dens is None:
dens = _simple_dens(eq, symbols)
if not any(checksol(di, {xi: vi}, minimal=True) is True
for di in dens):
# simplify any trivial integral
irep = [(i, i.doit()) for i in vi.atoms(Integral) if
i.function.is_number]
# do a slight bit of simplification
vi = expand_mul(vi.subs(irep))
return xi, vi
if all_zero:
return S.Zero, S.One
if n.is_Symbol: # no solution for this symbol was found
return S.Zero, S.Zero
return n, d
def minsolve_linear_system(system, *symbols, **flags):
r"""
Find a particular solution to a linear system.
Explanation
===========
In particular, try to find a solution with the minimal possible number
of non-zero variables using a naive algorithm with exponential complexity.
If ``quick=True``, a heuristic is used.
"""
quick = flags.get('quick', False)
# Check if there are any non-zero solutions at all
s0 = solve_linear_system(system, *symbols, **flags)
if not s0 or all(v == 0 for v in s0.values()):
return s0
if quick:
# We just solve the system and try to heuristically find a nice
# solution.
s = solve_linear_system(system, *symbols)
def update(determined, solution):
delete = []
for k, v in solution.items():
solution[k] = v.subs(determined)
if not solution[k].free_symbols:
delete.append(k)
determined[k] = solution[k]
for k in delete:
del solution[k]
determined = {}
update(determined, s)
while s:
# NOTE sort by default_sort_key to get deterministic result
k = max((k for k in s.values()),
key=lambda x: (len(x.free_symbols), default_sort_key(x)))
x = max(k.free_symbols, key=default_sort_key)
if len(k.free_symbols) != 1:
determined[x] = S.Zero
else:
val = solve(k)[0]
if val == 0 and all(v.subs(x, val) == 0 for v in s.values()):
determined[x] = S.One
else:
determined[x] = val
update(determined, s)
return determined
else:
# We try to select n variables which we want to be non-zero.
# All others will be assumed zero. We try to solve the modified system.
# If there is a non-trivial solution, just set the free variables to
# one. If we do this for increasing n, trying all combinations of
# variables, we will find an optimal solution.
# We speed up slightly by starting at one less than the number of
# variables the quick method manages.
from itertools import combinations
from sympy.utilities.misc import debug
N = len(symbols)
bestsol = minsolve_linear_system(system, *symbols, quick=True)
n0 = len([x for x in bestsol.values() if x != 0])
for n in range(n0 - 1, 1, -1):
debug('minsolve: %s' % n)
thissol = None
for nonzeros in combinations(list(range(N)), n):
subm = Matrix([system.col(i).T for i in nonzeros] + [system.col(-1).T]).T
s = solve_linear_system(subm, *[symbols[i] for i in nonzeros])
if s and not all(v == 0 for v in s.values()):
subs = [(symbols[v], S.One) for v in nonzeros]
for k, v in s.items():
s[k] = v.subs(subs)
for sym in symbols:
if sym not in s:
if symbols.index(sym) in nonzeros:
s[sym] = S.One
else:
s[sym] = S.Zero
thissol = s
break
if thissol is None:
break
bestsol = thissol
return bestsol
def solve_linear_system(system, *symbols, **flags):
r"""
Solve system of $N$ linear equations with $M$ variables, which means
both under- and overdetermined systems are supported.
Explanation
===========
The possible number of solutions is zero, one, or infinite. Respectively,
this procedure will return None or a dictionary with solutions. In the
case of underdetermined systems, all arbitrary parameters are skipped.
This may cause a situation in which an empty dictionary is returned.
In that case, all symbols can be assigned arbitrary values.
Input to this function is a $N\times M + 1$ matrix, which means it has
to be in augmented form. If you prefer to enter $N$ equations and $M$
unknowns then use ``solve(Neqs, *Msymbols)`` instead. Note: a local
copy of the matrix is made by this routine so the matrix that is
passed will not be modified.
The algorithm used here is fraction-free Gaussian elimination,
which results, after elimination, in an upper-triangular matrix.
Then solutions are found using back-substitution. This approach
is more efficient and compact than the Gauss-Jordan method.
Examples
========
>>> from sympy import Matrix, solve_linear_system
>>> from sympy.abc import x, y
Solve the following system::
x + 4 y == 2
-2 x + y == 14
>>> system = Matrix(( (1, 4, 2), (-2, 1, 14)))
>>> solve_linear_system(system, x, y)
{x: -6, y: 2}
A degenerate system returns an empty dictionary:
>>> system = Matrix(( (0,0,0), (0,0,0) ))
>>> solve_linear_system(system, x, y)
{}
"""
assert system.shape[1] == len(symbols) + 1
# This is just a wrapper for solve_lin_sys
eqs = list(system * Matrix(symbols + (-1,)))
eqs, ring = sympy_eqs_to_ring(eqs, symbols)
sol = solve_lin_sys(eqs, ring, _raw=False)
if sol is not None:
sol = {sym:val for sym, val in sol.items() if sym != val}
return sol
def solve_undetermined_coeffs(equ, coeffs, sym, **flags):
r"""
Solve equation of a type $p(x; a_1, \ldots, a_k) = q(x)$ where both
$p$ and $q$ are univariate polynomials that depend on $k$ parameters.
Explanation
===========
The result of this function is a dictionary with symbolic values of those
parameters with respect to coefficients in $q$.
This function accepts both equations class instances and ordinary
SymPy expressions. Specification of parameters and variables is
obligatory for efficiency and simplicity reasons.
Examples
========
>>> from sympy import Eq
>>> from sympy.abc import a, b, c, x
>>> from sympy.solvers import solve_undetermined_coeffs
>>> solve_undetermined_coeffs(Eq(2*a*x + a+b, x), [a, b], x)
{a: 1/2, b: -1/2}
>>> solve_undetermined_coeffs(Eq(a*c*x + a+b, x), [a, b], x)
{a: 1/c, b: -1/c}
"""
if isinstance(equ, Equality):
# got equation, so move all the
# terms to the left hand side
equ = equ.lhs - equ.rhs
equ = cancel(equ).as_numer_denom()[0]
system = list(collect(equ.expand(), sym, evaluate=False).values())
if not any(equ.has(sym) for equ in system):
# consecutive powers in the input expressions have
# been successfully collected, so solve remaining
# system using Gaussian elimination algorithm
return solve(system, *coeffs, **flags)
else:
return None # no solutions
def solve_linear_system_LU(matrix, syms):
"""
Solves the augmented matrix system using ``LUsolve`` and returns a
dictionary in which solutions are keyed to the symbols of *syms* as ordered.
Explanation
===========
The matrix must be invertible.
Examples
========
>>> from sympy import Matrix
>>> from sympy.abc import x, y, z
>>> from sympy.solvers.solvers import solve_linear_system_LU
>>> solve_linear_system_LU(Matrix([
... [1, 2, 0, 1],
... [3, 2, 2, 1],
... [2, 0, 0, 1]]), [x, y, z])
{x: 1/2, y: 1/4, z: -1/2}
See Also
========
LUsolve
"""
if matrix.rows != matrix.cols - 1:
raise ValueError("Rows should be equal to columns - 1")
A = matrix[:matrix.rows, :matrix.rows]
b = matrix[:, matrix.cols - 1:]
soln = A.LUsolve(b)
solutions = {}
for i in range(soln.rows):
solutions[syms[i]] = soln[i, 0]
return solutions
def det_perm(M):
"""
Return the determinant of *M* by using permutations to select factors.
Explanation
===========
For sizes larger than 8 the number of permutations becomes prohibitively
large, or if there are no symbols in the matrix, it is better to use the
standard determinant routines (e.g., ``M.det()``.)
See Also
========
det_minor
det_quick
"""
args = []
s = True
n = M.rows
list_ = M.flat()
for perm in generate_bell(n):
fac = []
idx = 0
for j in perm:
fac.append(list_[idx + j])
idx += n
term = Mul(*fac) # disaster with unevaluated Mul -- takes forever for n=7
args.append(term if s else -term)
s = not s
return Add(*args)
def det_minor(M):
"""
Return the ``det(M)`` computed from minors without
introducing new nesting in products.
See Also
========
det_perm
det_quick
"""
n = M.rows
if n == 2:
return M[0, 0]*M[1, 1] - M[1, 0]*M[0, 1]
else:
return sum([(1, -1)[i % 2]*Add(*[M[0, i]*d for d in
Add.make_args(det_minor(M.minor_submatrix(0, i)))])
if M[0, i] else S.Zero for i in range(n)])
def det_quick(M, method=None):
"""
Return ``det(M)`` assuming that either
there are lots of zeros or the size of the matrix
is small. If this assumption is not met, then the normal
Matrix.det function will be used with method = ``method``.
See Also
========
det_minor
det_perm
"""
if any(i.has(Symbol) for i in M):
if M.rows < 8 and all(i.has(Symbol) for i in M):
return det_perm(M)
return det_minor(M)
else:
return M.det(method=method) if method else M.det()
def inv_quick(M):
"""Return the inverse of ``M``, assuming that either
there are lots of zeros or the size of the matrix
is small.
"""
from sympy.matrices import zeros
if not all(i.is_Number for i in M):
if not any(i.is_Number for i in M):
det = lambda _: det_perm(_)
else:
det = lambda _: det_minor(_)
else:
return M.inv()
n = M.rows
d = det(M)
if d == S.Zero:
raise NonInvertibleMatrixError("Matrix det == 0; not invertible")
ret = zeros(n)
s1 = -1
for i in range(n):
s = s1 = -s1
for j in range(n):
di = det(M.minor_submatrix(i, j))
ret[j, i] = s*di/d
s = -s
return ret
# these are functions that have multiple inverse values per period
multi_inverses = {
sin: lambda x: (asin(x), S.Pi - asin(x)),
cos: lambda x: (acos(x), 2*S.Pi - acos(x)),
}
def _tsolve(eq, sym, **flags):
"""
Helper for ``_solve`` that solves a transcendental equation with respect
to the given symbol. Various equations containing powers and logarithms,
can be solved.
There is currently no guarantee that all solutions will be returned or
that a real solution will be favored over a complex one.
Either a list of potential solutions will be returned or None will be
returned (in the case that no method was known to get a solution
for the equation). All other errors (like the inability to cast an
expression as a Poly) are unhandled.
Examples
========
>>> from sympy import log
>>> from sympy.solvers.solvers import _tsolve as tsolve
>>> from sympy.abc import x
>>> tsolve(3**(2*x + 5) - 4, x)
[-5/2 + log(2)/log(3), (-5*log(3)/2 + log(2) + I*pi)/log(3)]
>>> tsolve(log(x) + 2*x, x)
[LambertW(2)/2]
"""
if 'tsolve_saw' not in flags:
flags['tsolve_saw'] = []
if eq in flags['tsolve_saw']:
return None
else:
flags['tsolve_saw'].append(eq)
rhs, lhs = _invert(eq, sym)
if lhs == sym:
return [rhs]
try:
if lhs.is_Add:
# it's time to try factoring; powdenest is used
# to try get powers in standard form for better factoring
f = factor(powdenest(lhs - rhs))
if f.is_Mul:
return _solve(f, sym, **flags)
if rhs:
f = logcombine(lhs, force=flags.get('force', True))
if f.count(log) != lhs.count(log):
if isinstance(f, log):
return _solve(f.args[0] - exp(rhs), sym, **flags)
return _tsolve(f - rhs, sym, **flags)
elif lhs.is_Pow:
if lhs.exp.is_Integer:
if lhs - rhs != eq:
return _solve(lhs - rhs, sym, **flags)
if sym not in lhs.exp.free_symbols:
return _solve(lhs.base - rhs**(1/lhs.exp), sym, **flags)
# _tsolve calls this with Dummy before passing the actual number in.
if any(t.is_Dummy for t in rhs.free_symbols):
raise NotImplementedError # _tsolve will call here again...
# a ** g(x) == 0
if not rhs:
# f(x)**g(x) only has solutions where f(x) == 0 and g(x) != 0 at
# the same place
sol_base = _solve(lhs.base, sym, **flags)
return [s for s in sol_base if lhs.exp.subs(sym, s) != 0]
# a ** g(x) == b
if not lhs.base.has(sym):
if lhs.base == 0:
return _solve(lhs.exp, sym, **flags) if rhs != 0 else []
# Gets most solutions...
if lhs.base == rhs.as_base_exp()[0]:
# handles case when bases are equal
sol = _solve(lhs.exp - rhs.as_base_exp()[1], sym, **flags)
else:
# handles cases when bases are not equal and exp
# may or may not be equal
sol = _solve(exp(log(lhs.base)*lhs.exp)-exp(log(rhs)), sym, **flags)
# Check for duplicate solutions
def equal(expr1, expr2):
_ = Dummy()
eq = checksol(expr1 - _, _, expr2)
if eq is None:
if nsimplify(expr1) != nsimplify(expr2):
return False
# they might be coincidentally the same
# so check more rigorously
eq = expr1.equals(expr2)
return eq
# Guess a rational exponent
e_rat = nsimplify(log(abs(rhs))/log(abs(lhs.base)))
e_rat = simplify(posify(e_rat)[0])
n, d = fraction(e_rat)
if expand(lhs.base**n - rhs**d) == 0:
sol = [s for s in sol if not equal(lhs.exp.subs(sym, s), e_rat)]
sol.extend(_solve(lhs.exp - e_rat, sym, **flags))
return list(ordered(set(sol)))
# f(x) ** g(x) == c
else:
sol = []
logform = lhs.exp*log(lhs.base) - log(rhs)
if logform != lhs - rhs:
try:
sol.extend(_solve(logform, sym, **flags))
except NotImplementedError:
pass
# Collect possible solutions and check with substitution later.
check = []
if rhs == 1:
# f(x) ** g(x) = 1 -- g(x)=0 or f(x)=+-1
check.extend(_solve(lhs.exp, sym, **flags))
check.extend(_solve(lhs.base - 1, sym, **flags))
check.extend(_solve(lhs.base + 1, sym, **flags))
elif rhs.is_Rational:
for d in (i for i in divisors(abs(rhs.p)) if i != 1):
e, t = integer_log(rhs.p, d)
if not t:
continue # rhs.p != d**b
for s in divisors(abs(rhs.q)):
if s**e== rhs.q:
r = Rational(d, s)
check.extend(_solve(lhs.base - r, sym, **flags))
check.extend(_solve(lhs.base + r, sym, **flags))
check.extend(_solve(lhs.exp - e, sym, **flags))
elif rhs.is_irrational:
b_l, e_l = lhs.base.as_base_exp()
n, d = (e_l*lhs.exp).as_numer_denom()
b, e = sqrtdenest(rhs).as_base_exp()
check = [sqrtdenest(i) for i in (_solve(lhs.base - b, sym, **flags))]
check.extend([sqrtdenest(i) for i in (_solve(lhs.exp - e, sym, **flags))])
if e_l*d != 1:
check.extend(_solve(b_l**n - rhs**(e_l*d), sym, **flags))
for s in check:
ok = checksol(eq, sym, s)
if ok is None:
ok = eq.subs(sym, s).equals(0)
if ok:
sol.append(s)
return list(ordered(set(sol)))
elif lhs.is_Function and len(lhs.args) == 1:
if lhs.func in multi_inverses:
# sin(x) = 1/3 -> x - asin(1/3) & x - (pi - asin(1/3))
soln = []
for i in multi_inverses[lhs.func](rhs):
soln.extend(_solve(lhs.args[0] - i, sym, **flags))
return list(ordered(soln))
elif lhs.func == LambertW:
return _solve(lhs.args[0] - rhs*exp(rhs), sym, **flags)
rewrite = lhs.rewrite(exp)
if rewrite != lhs:
return _solve(rewrite - rhs, sym, **flags)
except NotImplementedError:
pass
# maybe it is a lambert pattern
if flags.pop('bivariate', True):
# lambert forms may need some help being recognized, e.g. changing
# 2**(3*x) + x**3*log(2)**3 + 3*x**2*log(2)**2 + 3*x*log(2) + 1
# to 2**(3*x) + (x*log(2) + 1)**3
g = _filtered_gens(eq.as_poly(), sym)
up_or_log = set()
for gi in g:
if isinstance(gi, exp) or (gi.is_Pow and gi.base == S.Exp1) or isinstance(gi, log):
up_or_log.add(gi)
elif gi.is_Pow:
gisimp = powdenest(expand_power_exp(gi))
if gisimp.is_Pow and sym in gisimp.exp.free_symbols:
up_or_log.add(gi)
eq_down = expand_log(expand_power_exp(eq)).subs(
dict(list(zip(up_or_log, [0]*len(up_or_log)))))
eq = expand_power_exp(factor(eq_down, deep=True) + (eq - eq_down))
rhs, lhs = _invert(eq, sym)
if lhs.has(sym):
try:
poly = lhs.as_poly()
g = _filtered_gens(poly, sym)
_eq = lhs - rhs
sols = _solve_lambert(_eq, sym, g)
# use a simplified form if it satisfies eq
# and has fewer operations
for n, s in enumerate(sols):
ns = nsimplify(s)
if ns != s and ns.count_ops() <= s.count_ops():
ok = checksol(_eq, sym, ns)
if ok is None:
ok = _eq.subs(sym, ns).equals(0)
if ok:
sols[n] = ns
return sols
except NotImplementedError:
# maybe it's a convoluted function
if len(g) == 2:
try:
gpu = bivariate_type(lhs - rhs, *g)
if gpu is None:
raise NotImplementedError
g, p, u = gpu
flags['bivariate'] = False
inversion = _tsolve(g - u, sym, **flags)
if inversion:
sol = _solve(p, u, **flags)
return list(ordered({i.subs(u, s)
for i in inversion for s in sol}))
except NotImplementedError:
pass
else:
pass
if flags.pop('force', True):
flags['force'] = False
pos, reps = posify(lhs - rhs)
if rhs == S.ComplexInfinity:
return []
for u, s in reps.items():
if s == sym:
break
else:
u = sym
if pos.has(u):
try:
soln = _solve(pos, u, **flags)
return list(ordered([s.subs(reps) for s in soln]))
except NotImplementedError:
pass
else:
pass # here for coverage
return # here for coverage
# TODO: option for calculating J numerically
@conserve_mpmath_dps
def nsolve(*args, dict=False, **kwargs):
r"""
Solve a nonlinear equation system numerically: ``nsolve(f, [args,] x0,
modules=['mpmath'], **kwargs)``.
Explanation
===========
``f`` is a vector function of symbolic expressions representing the system.
*args* are the variables. If there is only one variable, this argument can
be omitted. ``x0`` is a starting vector close to a solution.
Use the modules keyword to specify which modules should be used to
evaluate the function and the Jacobian matrix. Make sure to use a module
that supports matrices. For more information on the syntax, please see the
docstring of ``lambdify``.
If the keyword arguments contain ``dict=True`` (default is False) ``nsolve``
will return a list (perhaps empty) of solution mappings. This might be
especially useful if you want to use ``nsolve`` as a fallback to solve since
using the dict argument for both methods produces return values of
consistent type structure. Please note: to keep this consistent with
``solve``, the solution will be returned in a list even though ``nsolve``
(currently at least) only finds one solution at a time.
Overdetermined systems are supported.
Examples
========
>>> from sympy import Symbol, nsolve
>>> import mpmath
>>> mpmath.mp.dps = 15
>>> x1 = Symbol('x1')
>>> x2 = Symbol('x2')
>>> f1 = 3 * x1**2 - 2 * x2**2 - 1
>>> f2 = x1**2 - 2 * x1 + x2**2 + 2 * x2 - 8
>>> print(nsolve((f1, f2), (x1, x2), (-1, 1)))
Matrix([[-1.19287309935246], [1.27844411169911]])
For one-dimensional functions the syntax is simplified:
>>> from sympy import sin, nsolve
>>> from sympy.abc import x
>>> nsolve(sin(x), x, 2)
3.14159265358979
>>> nsolve(sin(x), 2)
3.14159265358979
To solve with higher precision than the default, use the prec argument:
>>> from sympy import cos
>>> nsolve(cos(x) - x, 1)
0.739085133215161
>>> nsolve(cos(x) - x, 1, prec=50)
0.73908513321516064165531208767387340401341175890076
>>> cos(_)
0.73908513321516064165531208767387340401341175890076
To solve for complex roots of real functions, a nonreal initial point
must be specified:
>>> from sympy import I
>>> nsolve(x**2 + 2, I)
1.4142135623731*I
``mpmath.findroot`` is used and you can find their more extensive
documentation, especially concerning keyword parameters and
available solvers. Note, however, that functions which are very
steep near the root, the verification of the solution may fail. In
this case you should use the flag ``verify=False`` and
independently verify the solution.
>>> from sympy import cos, cosh
>>> f = cos(x)*cosh(x) - 1
>>> nsolve(f, 3.14*100)
Traceback (most recent call last):
...
ValueError: Could not find root within given tolerance. (1.39267e+230 > 2.1684e-19)
>>> ans = nsolve(f, 3.14*100, verify=False); ans
312.588469032184
>>> f.subs(x, ans).n(2)
2.1e+121
>>> (f/f.diff(x)).subs(x, ans).n(2)
7.4e-15
One might safely skip the verification if bounds of the root are known
and a bisection method is used:
>>> bounds = lambda i: (3.14*i, 3.14*(i + 1))
>>> nsolve(f, bounds(100), solver='bisect', verify=False)
315.730061685774
Alternatively, a function may be better behaved when the
denominator is ignored. Since this is not always the case, however,
the decision of what function to use is left to the discretion of
the user.
>>> eq = x**2/(1 - x)/(1 - 2*x)**2 - 100
>>> nsolve(eq, 0.46)
Traceback (most recent call last):
...
ValueError: Could not find root within given tolerance. (10000 > 2.1684e-19)
Try another starting point or tweak arguments.
>>> nsolve(eq.as_numer_denom()[0], 0.46)
0.46792545969349058
"""
# there are several other SymPy functions that use method= so
# guard against that here
if 'method' in kwargs:
raise ValueError(filldedent('''
Keyword "method" should not be used in this context. When using
some mpmath solvers directly, the keyword "method" is
used, but when using nsolve (and findroot) the keyword to use is
"solver".'''))
if 'prec' in kwargs:
prec = kwargs.pop('prec')
import mpmath
mpmath.mp.dps = prec
else:
prec = None
# keyword argument to return result as a dictionary
as_dict = dict
from builtins import dict # to unhide the builtin
# interpret arguments
if len(args) == 3:
f = args[0]
fargs = args[1]
x0 = args[2]
if iterable(fargs) and iterable(x0):
if len(x0) != len(fargs):
raise TypeError('nsolve expected exactly %i guess vectors, got %i'
% (len(fargs), len(x0)))
elif len(args) == 2:
f = args[0]
fargs = None
x0 = args[1]
if iterable(f):
raise TypeError('nsolve expected 3 arguments, got 2')
elif len(args) < 2:
raise TypeError('nsolve expected at least 2 arguments, got %i'
% len(args))
else:
raise TypeError('nsolve expected at most 3 arguments, got %i'
% len(args))
modules = kwargs.get('modules', ['mpmath'])
if iterable(f):
f = list(f)
for i, fi in enumerate(f):
if isinstance(fi, Equality):
f[i] = fi.lhs - fi.rhs
f = Matrix(f).T
if iterable(x0):
x0 = list(x0)
if not isinstance(f, Matrix):
# assume it's a sympy expression
if isinstance(f, Equality):
f = f.lhs - f.rhs
syms = f.free_symbols
if fargs is None:
fargs = syms.copy().pop()
if not (len(syms) == 1 and (fargs in syms or fargs[0] in syms)):
raise ValueError(filldedent('''
expected a one-dimensional and numerical function'''))
# the function is much better behaved if there is no denominator
# but sending the numerator is left to the user since sometimes
# the function is better behaved when the denominator is present
# e.g., issue 11768
f = lambdify(fargs, f, modules)
x = sympify(findroot(f, x0, **kwargs))
if as_dict:
return [{fargs: x}]
return x
if len(fargs) > f.cols:
raise NotImplementedError(filldedent('''
need at least as many equations as variables'''))
verbose = kwargs.get('verbose', False)
if verbose:
print('f(x):')
print(f)
# derive Jacobian
J = f.jacobian(fargs)
if verbose:
print('J(x):')
print(J)
# create functions
f = lambdify(fargs, f.T, modules)
J = lambdify(fargs, J, modules)
# solve the system numerically
x = findroot(f, x0, J=J, **kwargs)
if as_dict:
return [dict(zip(fargs, [sympify(xi) for xi in x]))]
return Matrix(x)
def _invert(eq, *symbols, **kwargs):
"""
Return tuple (i, d) where ``i`` is independent of *symbols* and ``d``
contains symbols.
Explanation
===========
``i`` and ``d`` are obtained after recursively using algebraic inversion
until an uninvertible ``d`` remains. If there are no free symbols then
``d`` will be zero. Some (but not necessarily all) solutions to the
expression ``i - d`` will be related to the solutions of the original
expression.
Examples
========
>>> from sympy.solvers.solvers import _invert as invert
>>> from sympy import sqrt, cos
>>> from sympy.abc import x, y
>>> invert(x - 3)
(3, x)
>>> invert(3)
(3, 0)
>>> invert(2*cos(x) - 1)
(1/2, cos(x))
>>> invert(sqrt(x) - 3)
(3, sqrt(x))
>>> invert(sqrt(x) + y, x)
(-y, sqrt(x))
>>> invert(sqrt(x) + y, y)
(-sqrt(x), y)
>>> invert(sqrt(x) + y, x, y)
(0, sqrt(x) + y)
If there is more than one symbol in a power's base and the exponent
is not an Integer, then the principal root will be used for the
inversion:
>>> invert(sqrt(x + y) - 2)
(4, x + y)
>>> invert(sqrt(x + y) - 2)
(4, x + y)
If the exponent is an Integer, setting ``integer_power`` to True
will force the principal root to be selected:
>>> invert(x**2 - 4, integer_power=True)
(2, x)
"""
eq = sympify(eq)
if eq.args:
# make sure we are working with flat eq
eq = eq.func(*eq.args)
free = eq.free_symbols
if not symbols:
symbols = free
if not free & set(symbols):
return eq, S.Zero
dointpow = bool(kwargs.get('integer_power', False))
lhs = eq
rhs = S.Zero
while True:
was = lhs
while True:
indep, dep = lhs.as_independent(*symbols)
# dep + indep == rhs
if lhs.is_Add:
# this indicates we have done it all
if indep.is_zero:
break
lhs = dep
rhs -= indep
# dep * indep == rhs
else:
# this indicates we have done it all
if indep is S.One:
break
lhs = dep
rhs /= indep
# collect like-terms in symbols
if lhs.is_Add:
terms = {}
for a in lhs.args:
i, d = a.as_independent(*symbols)
terms.setdefault(d, []).append(i)
if any(len(v) > 1 for v in terms.values()):
args = []
for d, i in terms.items():
if len(i) > 1:
args.append(Add(*i)*d)
else:
args.append(i[0]*d)
lhs = Add(*args)
# if it's a two-term Add with rhs = 0 and two powers we can get the
# dependent terms together, e.g. 3*f(x) + 2*g(x) -> f(x)/g(x) = -2/3
if lhs.is_Add and not rhs and len(lhs.args) == 2 and \
not lhs.is_polynomial(*symbols):
a, b = ordered(lhs.args)
ai, ad = a.as_independent(*symbols)
bi, bd = b.as_independent(*symbols)
if any(_ispow(i) for i in (ad, bd)):
a_base, a_exp = ad.as_base_exp()
b_base, b_exp = bd.as_base_exp()
if a_base == b_base:
# a = -b
lhs = powsimp(powdenest(ad/bd))
rhs = -bi/ai
else:
rat = ad/bd
_lhs = powsimp(ad/bd)
if _lhs != rat:
lhs = _lhs
rhs = -bi/ai
elif ai == -bi:
if isinstance(ad, Function) and ad.func == bd.func:
if len(ad.args) == len(bd.args) == 1:
lhs = ad.args[0] - bd.args[0]
elif len(ad.args) == len(bd.args):
# should be able to solve
# f(x, y) - f(2 - x, 0) == 0 -> x == 1
raise NotImplementedError(
'equal function with more than 1 argument')
else:
raise ValueError(
'function with different numbers of args')
elif lhs.is_Mul and any(_ispow(a) for a in lhs.args):
lhs = powsimp(powdenest(lhs))
if lhs.is_Function:
if hasattr(lhs, 'inverse') and lhs.inverse() is not None and len(lhs.args) == 1:
# -1
# f(x) = g -> x = f (g)
#
# /!\ inverse should not be defined if there are multiple values
# for the function -- these are handled in _tsolve
#
rhs = lhs.inverse()(rhs)
lhs = lhs.args[0]
elif isinstance(lhs, atan2):
y, x = lhs.args
lhs = 2*atan(y/(sqrt(x**2 + y**2) + x))
elif lhs.func == rhs.func:
if len(lhs.args) == len(rhs.args) == 1:
lhs = lhs.args[0]
rhs = rhs.args[0]
elif len(lhs.args) == len(rhs.args):
# should be able to solve
# f(x, y) == f(2, 3) -> x == 2
# f(x, x + y) == f(2, 3) -> x == 2
raise NotImplementedError(
'equal function with more than 1 argument')
else:
raise ValueError(
'function with different numbers of args')
if rhs and lhs.is_Pow and lhs.exp.is_Integer and lhs.exp < 0:
lhs = 1/lhs
rhs = 1/rhs
# base**a = b -> base = b**(1/a) if
# a is an Integer and dointpow=True (this gives real branch of root)
# a is not an Integer and the equation is multivariate and the
# base has more than 1 symbol in it
# The rationale for this is that right now the multi-system solvers
# doesn't try to resolve generators to see, for example, if the whole
# system is written in terms of sqrt(x + y) so it will just fail, so we
# do that step here.
if lhs.is_Pow and (
lhs.exp.is_Integer and dointpow or not lhs.exp.is_Integer and
len(symbols) > 1 and len(lhs.base.free_symbols & set(symbols)) > 1):
rhs = rhs**(1/lhs.exp)
lhs = lhs.base
if lhs == was:
break
return rhs, lhs
def unrad(eq, *syms, **flags):
"""
Remove radicals with symbolic arguments and return (eq, cov),
None, or raise an error.
Explanation
===========
None is returned if there are no radicals to remove.
NotImplementedError is raised if there are radicals and they cannot be
removed or if the relationship between the original symbols and the
change of variable needed to rewrite the system as a polynomial cannot
be solved.
Otherwise the tuple, ``(eq, cov)``, is returned where:
*eq*, ``cov``
*eq* is an equation without radicals (in the symbol(s) of
interest) whose solutions are a superset of the solutions to the
original expression. *eq* might be rewritten in terms of a new
variable; the relationship to the original variables is given by
``cov`` which is a list containing ``v`` and ``v**p - b`` where
``p`` is the power needed to clear the radical and ``b`` is the
radical now expressed as a polynomial in the symbols of interest.
For example, for sqrt(2 - x) the tuple would be
``(c, c**2 - 2 + x)``. The solutions of *eq* will contain
solutions to the original equation (if there are any).
*syms*
An iterable of symbols which, if provided, will limit the focus of
radical removal: only radicals with one or more of the symbols of
interest will be cleared. All free symbols are used if *syms* is not
set.
*flags* are used internally for communication during recursive calls.
Two options are also recognized:
``take``, when defined, is interpreted as a single-argument function
that returns True if a given Pow should be handled.
Radicals can be removed from an expression if:
* All bases of the radicals are the same; a change of variables is
done in this case.
* If all radicals appear in one term of the expression.
* There are only four terms with sqrt() factors or there are less than
four terms having sqrt() factors.
* There are only two terms with radicals.
Examples
========
>>> from sympy.solvers.solvers import unrad
>>> from sympy.abc import x
>>> from sympy import sqrt, Rational, root
>>> unrad(sqrt(x)*x**Rational(1, 3) + 2)
(x**5 - 64, [])
>>> unrad(sqrt(x) + root(x + 1, 3))
(-x**3 + x**2 + 2*x + 1, [])
>>> eq = sqrt(x) + root(x, 3) - 2
>>> unrad(eq)
(_p**3 + _p**2 - 2, [_p, _p**6 - x])
"""
from sympy import Equality as Eq
uflags = dict(check=False, simplify=False)
def _cov(p, e):
if cov:
# XXX - uncovered
oldp, olde = cov
if Poly(e, p).degree(p) in (1, 2):
cov[:] = [p, olde.subs(oldp, _solve(e, p, **uflags)[0])]
else:
raise NotImplementedError
else:
cov[:] = [p, e]
def _canonical(eq, cov):
if cov:
# change symbol to vanilla so no solutions are eliminated
p, e = cov
rep = {p: Dummy(p.name)}
eq = eq.xreplace(rep)
cov = [p.xreplace(rep), e.xreplace(rep)]
# remove constants and powers of factors since these don't change
# the location of the root; XXX should factor or factor_terms be used?
eq = factor_terms(_mexpand(eq.as_numer_denom()[0], recursive=True), clear=True)
if eq.is_Mul:
args = []
for f in eq.args:
if f.is_number:
continue
if f.is_Pow:
args.append(f.base)
else:
args.append(f)
eq = Mul(*args) # leave as Mul for more efficient solving
# make the sign canonical
margs = list(Mul.make_args(eq))
changed = False
for i, m in enumerate(margs):
if m.could_extract_minus_sign():
margs[i] = -m
changed = True
if changed:
eq = Mul(*margs, evaluate=False)
return eq, cov
def _Q(pow):
# return leading Rational of denominator of Pow's exponent
c = pow.as_base_exp()[1].as_coeff_Mul()[0]
if not c.is_Rational:
return S.One
return c.q
# define the _take method that will determine whether a term is of interest
def _take(d):
# return True if coefficient of any factor's exponent's den is not 1
for pow in Mul.make_args(d):
if not pow.is_Pow:
continue
if _Q(pow) == 1:
continue
if pow.free_symbols & syms:
return True
return False
_take = flags.setdefault('_take', _take)
if isinstance(eq, Eq):
eq = eq.lhs - eq.rhs # XXX legacy Eq as Eqn support
elif not isinstance(eq, Expr):
return
cov, nwas, rpt = [flags.setdefault(k, v) for k, v in
sorted(dict(cov=[], n=None, rpt=0).items())]
# preconditioning
eq = powdenest(factor_terms(eq, radical=True, clear=True))
eq = eq.as_numer_denom()[0]
eq = _mexpand(eq, recursive=True)
if eq.is_number:
return
# see if there are radicals in symbols of interest
syms = set(syms) or eq.free_symbols # _take uses this
poly = eq.as_poly()
gens = [g for g in poly.gens if _take(g)]
if not gens:
return
# recast poly in terms of eigen-gens
poly = eq.as_poly(*gens)
# - an exponent has a symbol of interest (don't handle)
if any(g.exp.has(*syms) for g in gens):
return
def _rads_bases_lcm(poly):
# if all the bases are the same or all the radicals are in one
# term, `lcm` will be the lcm of the denominators of the
# exponents of the radicals
lcm = 1
rads = set()
bases = set()
for g in poly.gens:
q = _Q(g)
if q != 1:
rads.add(g)
lcm = ilcm(lcm, q)
bases.add(g.base)
return rads, bases, lcm
rads, bases, lcm = _rads_bases_lcm(poly)
covsym = Dummy('p', nonnegative=True)
# only keep in syms symbols that actually appear in radicals;
# and update gens
newsyms = set()
for r in rads:
newsyms.update(syms & r.free_symbols)
if newsyms != syms:
syms = newsyms
# get terms together that have common generators
drad = dict(list(zip(rads, list(range(len(rads))))))
rterms = {(): []}
args = Add.make_args(poly.as_expr())
for t in args:
if _take(t):
common = set(t.as_poly().gens).intersection(rads)
key = tuple(sorted([drad[i] for i in common]))
else:
key = ()
rterms.setdefault(key, []).append(t)
others = Add(*rterms.pop(()))
rterms = [Add(*rterms[k]) for k in rterms.keys()]
# the output will depend on the order terms are processed, so
# make it canonical quickly
rterms = list(reversed(list(ordered(rterms))))
ok = False # we don't have a solution yet
depth = sqrt_depth(eq)
if len(rterms) == 1 and not (rterms[0].is_Add and lcm > 2):
eq = rterms[0]**lcm - ((-others)**lcm)
ok = True
else:
if len(rterms) == 1 and rterms[0].is_Add:
rterms = list(rterms[0].args)
if len(bases) == 1:
b = bases.pop()
if len(syms) > 1:
x = b.free_symbols
else:
x = syms
x = list(ordered(x))[0]
try:
inv = _solve(covsym**lcm - b, x, **uflags)
if not inv:
raise NotImplementedError
eq = poly.as_expr().subs(b, covsym**lcm).subs(x, inv[0])
_cov(covsym, covsym**lcm - b)
return _canonical(eq, cov)
except NotImplementedError:
pass
if len(rterms) == 2:
if not others:
eq = rterms[0]**lcm - (-rterms[1])**lcm
ok = True
elif not log(lcm, 2).is_Integer:
# the lcm-is-power-of-two case is handled below
r0, r1 = rterms
if flags.get('_reverse', False):
r1, r0 = r0, r1
i0 = _rads0, _bases0, lcm0 = _rads_bases_lcm(r0.as_poly())
i1 = _rads1, _bases1, lcm1 = _rads_bases_lcm(r1.as_poly())
for reverse in range(2):
if reverse:
i0, i1 = i1, i0
r0, r1 = r1, r0
_rads1, _, lcm1 = i1
_rads1 = Mul(*_rads1)
t1 = _rads1**lcm1
c = covsym**lcm1 - t1
for x in syms:
try:
sol = _solve(c, x, **uflags)
if not sol:
raise NotImplementedError
neweq = r0.subs(x, sol[0]) + covsym*r1/_rads1 + \
others
tmp = unrad(neweq, covsym)
if tmp:
eq, newcov = tmp
if newcov:
newp, newc = newcov
_cov(newp, c.subs(covsym,
_solve(newc, covsym, **uflags)[0]))
else:
_cov(covsym, c)
else:
eq = neweq
_cov(covsym, c)
ok = True
break
except NotImplementedError:
if reverse:
raise NotImplementedError(
'no successful change of variable found')
else:
pass
if ok:
break
elif len(rterms) == 3:
# two cube roots and another with order less than 5
# (so an analytical solution can be found) or a base
# that matches one of the cube root bases
info = [_rads_bases_lcm(i.as_poly()) for i in rterms]
RAD = 0
BASES = 1
LCM = 2
if info[0][LCM] != 3:
info.append(info.pop(0))
rterms.append(rterms.pop(0))
elif info[1][LCM] != 3:
info.append(info.pop(1))
rterms.append(rterms.pop(1))
if info[0][LCM] == info[1][LCM] == 3:
if info[1][BASES] != info[2][BASES]:
info[0], info[1] = info[1], info[0]
rterms[0], rterms[1] = rterms[1], rterms[0]
if info[1][BASES] == info[2][BASES]:
eq = rterms[0]**3 + (rterms[1] + rterms[2] + others)**3
ok = True
elif info[2][LCM] < 5:
# a*root(A, 3) + b*root(B, 3) + others = c
a, b, c, d, A, B = [Dummy(i) for i in 'abcdAB']
# zz represents the unraded expression into which the
# specifics for this case are substituted
zz = (c - d)*(A**3*a**9 + 3*A**2*B*a**6*b**3 -
3*A**2*a**6*c**3 + 9*A**2*a**6*c**2*d - 9*A**2*a**6*c*d**2 +
3*A**2*a**6*d**3 + 3*A*B**2*a**3*b**6 + 21*A*B*a**3*b**3*c**3 -
63*A*B*a**3*b**3*c**2*d + 63*A*B*a**3*b**3*c*d**2 -
21*A*B*a**3*b**3*d**3 + 3*A*a**3*c**6 - 18*A*a**3*c**5*d +
45*A*a**3*c**4*d**2 - 60*A*a**3*c**3*d**3 + 45*A*a**3*c**2*d**4 -
18*A*a**3*c*d**5 + 3*A*a**3*d**6 + B**3*b**9 - 3*B**2*b**6*c**3 +
9*B**2*b**6*c**2*d - 9*B**2*b**6*c*d**2 + 3*B**2*b**6*d**3 +
3*B*b**3*c**6 - 18*B*b**3*c**5*d + 45*B*b**3*c**4*d**2 -
60*B*b**3*c**3*d**3 + 45*B*b**3*c**2*d**4 - 18*B*b**3*c*d**5 +
3*B*b**3*d**6 - c**9 + 9*c**8*d - 36*c**7*d**2 + 84*c**6*d**3 -
126*c**5*d**4 + 126*c**4*d**5 - 84*c**3*d**6 + 36*c**2*d**7 -
9*c*d**8 + d**9)
def _t(i):
b = Mul(*info[i][RAD])
return cancel(rterms[i]/b), Mul(*info[i][BASES])
aa, AA = _t(0)
bb, BB = _t(1)
cc = -rterms[2]
dd = others
eq = zz.xreplace(dict(zip(
(a, A, b, B, c, d),
(aa, AA, bb, BB, cc, dd))))
ok = True
# handle power-of-2 cases
if not ok:
if log(lcm, 2).is_Integer and (not others and
len(rterms) == 4 or len(rterms) < 4):
def _norm2(a, b):
return a**2 + b**2 + 2*a*b
if len(rterms) == 4:
# (r0+r1)**2 - (r2+r3)**2
r0, r1, r2, r3 = rterms
eq = _norm2(r0, r1) - _norm2(r2, r3)
ok = True
elif len(rterms) == 3:
# (r1+r2)**2 - (r0+others)**2
r0, r1, r2 = rterms
eq = _norm2(r1, r2) - _norm2(r0, others)
ok = True
elif len(rterms) == 2:
# r0**2 - (r1+others)**2
r0, r1 = rterms
eq = r0**2 - _norm2(r1, others)
ok = True
new_depth = sqrt_depth(eq) if ok else depth
rpt += 1 # XXX how many repeats with others unchanging is enough?
if not ok or (
nwas is not None and len(rterms) == nwas and
new_depth is not None and new_depth == depth and
rpt > 3):
raise NotImplementedError('Cannot remove all radicals')
flags.update(dict(cov=cov, n=len(rterms), rpt=rpt))
neq = unrad(eq, *syms, **flags)
if neq:
eq, cov = neq
eq, cov = _canonical(eq, cov)
return eq, cov
from sympy.solvers.bivariate import (
bivariate_type, _solve_lambert, _filtered_gens)
|
f34ad89c9c2d15604dcec6a428a0f4cc6f3928af263000086e52237a4a313552 | """
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
- ...
"""
import os
import textwrap
from io import StringIO
from sympy import __version__ as sympy_version
from sympy.core import Symbol, S, Tuple, Equality, Function, Basic
from sympy.core.compatibility import is_sequence
from sympy.printing.c import c_code_printers
from sympy.printing.codeprinter import AssignmentError
from sympy.printing.fortran 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:
"""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 = {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:
"""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"),
"complex": DataType("double", "COMPLEX*16", "complex", "", "", "float") #FIXME:
# complex is only supported in fortran, python, julia, and octave.
# So to not break c or rust code generation, we stick with double or
# float, respecitvely (but actually should raise an exception for
# explicitly complex variables (x.is_complex==True))
}
COMPLEX_ALLOWED = False
def get_default_datatype(expr, complex_allowed=None):
"""Derives an appropriate datatype based on the expression."""
if complex_allowed is None:
complex_allowed = COMPLEX_ALLOWED
if complex_allowed:
final_dtype = "complex"
else:
final_dtype = "float"
if expr.is_integer:
return default_datatypes["int"]
elif expr.is_real:
return default_datatypes["float"]
elif isinstance(expr, MatrixBase):
#check all entries
dt = "int"
for element in expr:
if dt == "int" and not element.is_integer:
dt = "float"
if dt == "float" and not element.is_real:
return default_datatypes[final_dtype]
return default_datatypes[dt]
else:
return default_datatypes[final_dtype]
class Variable:
"""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:
"""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 expr 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 datatype is None:
#try to infer data type from the expression
datatype = get_default_datatype(expr)
if isinstance(name, str):
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:
"""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:
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 = {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
# helper to get dimensions for data for array-like args
def dimensions(s):
return [(S.Zero, dim - 1) for dim in s.shape]
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:
array = array_symbols[symbol]
metadata = {'dimensions': dimensions(array)}
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:
if isinstance(symbol, (IndexedBase, MatrixSymbol)):
metadata = {'dimensions': dimensions(symbol)}
else:
metadata = {}
new_args.append(InputArgument(symbol, **metadata))
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().__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
code_lines.append("{} {}[{}];\n".format(t, str(assign_to), dims[0]*dims[1]))
prefix = ""
else:
prefix = "const {} ".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("{} {};\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 # type: ignore
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 # type: ignore
# 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().__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 = "{}({})\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 # type: ignore
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 # type: ignore
# 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().__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 # type: ignore
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().__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 # type: ignore
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().__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 = {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 = {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 # type: ignore
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], str):
# 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)
|
2db90714f1016e33fb7cc426cd1fa9613e536e5bdb1505e7136351608e821981 | """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, e.g.,
>>> from sympy.abc import x,y
>>> expr = (x - y)**25
>>> flat = expr.expand()
>>> binary_callable = autowrap(flat)
>>> binary_callable(2, 3)
-1.0
Although a SymPy user might primarily be interested in working with
mathematical expressions and not in the details of wrapping tools
needed to evaluate such expressions efficiently in numerical form,
the user cannot do so without some understanding of the
limits in the target language. For example, the expanded expression
contains large coefficients which result in loss of precision when
computing the expression:
>>> binary_callable(3, 2)
0.0
>>> binary_callable(4, 5), binary_callable(5, 4)
(-22925376.0, 25165824.0)
Wrapping the unexpanded expression gives the expected behavior:
>>> e = autowrap(expr)
>>> e(4, 5), e(5, 4)
(-1.0, 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
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.
"""
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 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:
"""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=None):
helpers = helpers or []
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().__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 = [self._string_var(v) for v in val]
local_decs.append(" cdef {} = {}.shape[{}]".format(proto, mat, ind))
local_decs.extend([" cdef {}".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([self._string_var(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=self._string_var(arg.name))
else:
return "%s %s" % (t, self._string_var(arg.name))
def _declare_arg(self, arg):
proto = self._prototype_arg(arg)
if arg.dimensions:
shape = '(' + ','.join(self._string_var(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 "<{}*> {}.data".format(t, self._string_var(arg.name))
elif isinstance(arg, ResultBase):
return "&{}".format(self._string_var(arg.name))
else:
return self._string_var(arg.name)
def _string_var(self, var):
printer = self.generator.printer.doprint
return printer(var)
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().__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 {} and language {} 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().__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:
if len(routines) == 1:
funcname = routines[0].name
else:
msg = 'funcname must be specified for multiple output routines'
raise ValueError(msg)
functions = []
function_creation = []
ufunc_init = []
module = self.module_name
include_file = "\"{}.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{};".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)
|
287cdc0d290b043e41231718dabb5eca60cbeec43927291f7d3196bba08b21c9 | """
This module provides convenient functions to transform sympy expressions to
lambda functions which can be used to calculate numerical values very fast.
"""
from typing import Any, Dict, Iterable
import builtins
import inspect
import keyword
import textwrap
import linecache
from sympy.utilities.exceptions import SymPyDeprecationWarning
from sympy.core.compatibility import (is_sequence, iterable,
NotIterable)
from sympy.utilities.misc import filldedent
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 = {} # type: Dict[str, Any]
MPMATH_DEFAULT = {} # type: Dict[str, Any]
NUMPY_DEFAULT = {"I": 1j} # type: Dict[str, Any]
SCIPY_DEFAULT = {"I": 1j} # type: Dict[str, Any]
CUPY_DEFAULT = {"I": 1j} # type: Dict[str, Any]
TENSORFLOW_DEFAULT = {} # type: Dict[str, Any]
SYMPY_DEFAULT = {} # type: Dict[str, Any]
NUMEXPR_DEFAULT = {} # type: Dict[str, Any]
# 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()
CUPY = CUPY_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",
}
# NOTE: This dictionary is reused in Function._eval_evalf to allow subclasses
# of Function to automatically evalf.
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",
"betainc_regularized": "betainc",
}
NUMPY_TRANSLATIONS = {
"Heaviside": "heaviside",
} # type: Dict[str, str]
SCIPY_TRANSLATIONS = {} # type: Dict[str, str]
CUPY_TRANSLATIONS = {} # type: Dict[str, str]
TENSORFLOW_TRANSLATIONS = {} # type: Dict[str, str]
NUMEXPR_TRANSLATIONS = {} # type: Dict[str, str]
# 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 *",)),
"cupy": (CUPY, CUPY_DEFAULT, CUPY_TRANSLATIONS, ("import cupy",)),
"tensorflow": (TENSORFLOW, TENSORFLOW_DEFAULT, TENSORFLOW_TRANSLATIONS, ("import 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 # noqa:F401
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', 'tensorflow',), python_version=(3,))
def lambdify(args: Iterable, expr, modules=None, printer=None, use_imps=True,
dummify=False, cse=False):
"""Convert a SymPy expression into a function that allows for fast
numeric evaluation.
.. warning::
This function uses ``exec``, and thus shouldn't be used on
unsanitized input.
.. versionchanged:: 1.7.0
Passing a set for the *args* parameter is deprecated as sets are
unordered. Use an ordered iterable such as a list or tuple.
Explanation
===========
For example, to convert the SymPy expression ``sin(x) + cos(x)`` to an
equivalent NumPy function that numerically evaluates it:
>>> from sympy import sin, cos, symbols, lambdify
>>> import numpy as np
>>> x = symbols('x')
>>> expr = sin(x) + cos(x)
>>> expr
sin(x) + cos(x)
>>> f = lambdify(x, expr, 'numpy')
>>> a = np.array([1, 2])
>>> f(a)
[1.38177329 0.49315059]
The primary purpose of this function is to provide a bridge from SymPy
expressions to numerical libraries such as NumPy, SciPy, NumExpr, mpmath,
and tensorflow. In general, SymPy functions do not work with objects from
other libraries, such as NumPy arrays, and functions from numeric
libraries like NumPy or mpmath do not work on SymPy expressions.
``lambdify`` bridges the two by converting a SymPy expression to an
equivalent numeric function.
The basic workflow with ``lambdify`` is to first create a SymPy expression
representing whatever mathematical function you wish to evaluate. This
should be done using only SymPy functions and expressions. Then, use
``lambdify`` to convert this to an equivalent function for numerical
evaluation. For instance, above we created ``expr`` using the SymPy symbol
``x`` and SymPy functions ``sin`` and ``cos``, then converted it to an
equivalent NumPy function ``f``, and called it on a NumPy array ``a``.
Parameters
==========
args : List[Symbol]
A variable or a list of variables whose nesting represents the
nesting of the arguments that will be passed to the function.
Variables can be symbols, undefined functions, or matrix symbols.
>>> from sympy import Eq
>>> from sympy.abc import x, y, z
The list of variables should match the structure of how the
arguments will be passed to the function. Simply enclose the
parameters as they will be passed in a list.
To call a function like ``f(x)`` then ``[x]``
should be the first argument to ``lambdify``; for this
case a single ``x`` can also be used:
>>> f = lambdify(x, x + 1)
>>> f(1)
2
>>> f = lambdify([x], x + 1)
>>> f(1)
2
To call a function like ``f(x, y)`` then ``[x, y]`` will
be the first argument of the ``lambdify``:
>>> f = lambdify([x, y], x + y)
>>> f(1, 1)
2
To call a function with a single 3-element tuple like
``f((x, y, z))`` then ``[(x, y, z)]`` will be the first
argument of the ``lambdify``:
>>> f = lambdify([(x, y, z)], Eq(z**2, x**2 + y**2))
>>> f((3, 4, 5))
True
If two args will be passed and the first is a scalar but
the second is a tuple with two arguments then the items
in the list should match that structure:
>>> f = lambdify([x, (y, z)], x + y + z)
>>> f(1, (2, 3))
6
expr : Expr
An expression, list of expressions, or matrix to be evaluated.
Lists may be nested.
If the expression is a list, the output will also be a list.
>>> f = lambdify(x, [x, [x + 1, x + 2]])
>>> f(1)
[1, [2, 3]]
If it is a matrix, an array will be returned (for the NumPy module).
>>> from sympy import Matrix
>>> f = lambdify(x, Matrix([x, x + 1]))
>>> f(1)
[[1]
[2]]
Note that the argument order here (variables then expression) is used
to emulate the Python ``lambda`` keyword. ``lambdify(x, expr)`` works
(roughly) like ``lambda x: expr``
(see :ref:`lambdify-how-it-works` below).
modules : str, optional
Specifies the numeric library to use.
If not specified, *modules* defaults to:
- ``["scipy", "numpy"]`` if SciPy is installed
- ``["numpy"]`` if only NumPy is installed
- ``["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.
*modules* can be one of the following types:
- The strings ``"math"``, ``"mpmath"``, ``"numpy"``, ``"numexpr"``,
``"scipy"``, ``"sympy"``, or ``"tensorflow"``. This uses the
corresponding printer and namespace mapping for that module.
- A module (e.g., ``math``). This uses the global namespace of the
module. If the module is one of the above known modules, it will
also use the corresponding printer and namespace mapping
(i.e., ``modules=numpy`` is equivalent to ``modules="numpy"``).
- A dictionary that maps names of SymPy functions to arbitrary
functions
(e.g., ``{'sin': custom_sin}``).
- A list that contains a mix of the arguments above, with higher
priority given to entries appearing first
(e.g., to use the NumPy module but override the ``sin`` function
with a custom version, you can use
``[{'sin': custom_sin}, 'numpy']``).
dummify : bool, optional
Whether or not the variables in the provided expression that are not
valid Python identifiers are substituted with dummy symbols.
This allows for undefined functions like ``Function('f')(t)`` to be
supplied as arguments. By default, the variables are only dummified
if they are not valid Python identifiers.
Set ``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.
cse : bool, or callable, optional
Large expressions can be computed more efficiently when
common subexpressions are identified and precomputed before
being used multiple time. Finding the subexpressions will make
creation of the 'lambdify' function slower, however.
When ``True``, ``sympy.simplify.cse`` is used, otherwise (the default)
the user may pass a function matching the ``cse`` signature.
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]])
``lambdify`` can be used to translate SymPy expressions into mpmath
functions. This may be preferable to using ``evalf`` (which uses mpmath on
the backend) in some cases.
>>> f = lambdify(x, sin(x), 'mpmath')
>>> f(1)
0.8414709848078965
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
The ``flatten`` function can be used 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. This
can be used with undefined functions 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:
>>> import tensorflow as tf
>>> from sympy import Max, sin, lambdify
>>> from sympy.abc import x
>>> f = Max(x, sin(x))
>>> func = lambdify(x, f, 'tensorflow')
After tensorflow v2, eager execution is enabled by default.
If you want to get the compatible result across tensorflow v1 and v2
as same as this tutorial, run this line.
>>> tf.compat.v1.enable_eager_execution()
If you have eager execution enabled, you can get the result out
immediately as you can use numpy.
If you pass tensorflow objects, you may get an ``EagerTensor``
object instead of value.
>>> result = func(tf.constant(1.0))
>>> print(result)
tf.Tensor(1.0, shape=(), dtype=float32)
>>> print(result.__class__)
<class 'tensorflow.python.framework.ops.EagerTensor'>
You can use ``.numpy()`` to get the numpy value of the tensor.
>>> result.numpy()
1.0
>>> var = tf.Variable(2.0)
>>> result = func(var) # also works for tf.Variable and tf.Placeholder
>>> result.numpy()
2.0
And it works with any shape array.
>>> tensor = tf.constant([[1.0, 2.0], [3.0, 4.0]])
>>> result = func(tensor)
>>> result.numpy()
[[1. 2.]
[3. 4.]]
Notes
=====
- 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://numexpr.readthedocs.io/en/latest/user_guide.html#supported-functions
- In previous versions of SymPy, ``lambdify`` replaced ``Matrix`` with
``numpy.matrix`` by default. As of SymPy 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]]
- 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.testing.pytest import ignore_warnings
>>> f = lambdify(x, Piecewise((x, x <= 1), (1/x, x > 1)), "numpy")
>>> with ignore_warnings(RuntimeWarning):
... f(numpy.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(numpy.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
.. _lambdify-how-it-works:
How it works
============
When using this function, it helps a great deal to have an idea of what it
is doing. At its core, lambdify is nothing more than a namespace
translation, on top of a special printer that makes some corner cases work
properly.
To understand lambdify, first we must properly understand how Python
namespaces work. Say we had two files. One called ``sin_cos_sympy.py``,
with
.. code:: python
# sin_cos_sympy.py
from sympy import sin, cos
def sin_cos(x):
return sin(x) + cos(x)
and one called ``sin_cos_numpy.py`` with
.. code:: python
# sin_cos_numpy.py
from numpy import sin, cos
def sin_cos(x):
return sin(x) + cos(x)
The two files define an identical function ``sin_cos``. However, in the
first file, ``sin`` and ``cos`` are defined as the SymPy ``sin`` and
``cos``. In the second, they are defined as the NumPy versions.
If we were to import the first file and use the ``sin_cos`` function, we
would get something like
>>> from sin_cos_sympy import sin_cos # doctest: +SKIP
>>> sin_cos(1) # doctest: +SKIP
cos(1) + sin(1)
On the other hand, if we imported ``sin_cos`` from the second file, we
would get
>>> from sin_cos_numpy import sin_cos # doctest: +SKIP
>>> sin_cos(1) # doctest: +SKIP
1.38177329068
In the first case we got a symbolic output, because it used the symbolic
``sin`` and ``cos`` functions from SymPy. In the second, we got a numeric
result, because ``sin_cos`` used the numeric ``sin`` and ``cos`` functions
from NumPy. But notice that the versions of ``sin`` and ``cos`` that were
used was not inherent to the ``sin_cos`` function definition. Both
``sin_cos`` definitions are exactly the same. Rather, it was based on the
names defined at the module where the ``sin_cos`` function was defined.
The key point here is that when function in Python references a name that
is not defined in the function, that name is looked up in the "global"
namespace of the module where that function is defined.
Now, in Python, we can emulate this behavior without actually writing a
file to disk using the ``exec`` function. ``exec`` takes a string
containing a block of Python code, and a dictionary that should contain
the global variables of the module. It then executes the code "in" that
dictionary, as if it were the module globals. The following is equivalent
to the ``sin_cos`` defined in ``sin_cos_sympy.py``:
>>> import sympy
>>> module_dictionary = {'sin': sympy.sin, 'cos': sympy.cos}
>>> exec('''
... def sin_cos(x):
... return sin(x) + cos(x)
... ''', module_dictionary)
>>> sin_cos = module_dictionary['sin_cos']
>>> sin_cos(1)
cos(1) + sin(1)
and similarly with ``sin_cos_numpy``:
>>> import numpy
>>> module_dictionary = {'sin': numpy.sin, 'cos': numpy.cos}
>>> exec('''
... def sin_cos(x):
... return sin(x) + cos(x)
... ''', module_dictionary)
>>> sin_cos = module_dictionary['sin_cos']
>>> sin_cos(1)
1.38177329068
So now we can get an idea of how ``lambdify`` works. The name "lambdify"
comes from the fact that we can think of something like ``lambdify(x,
sin(x) + cos(x), 'numpy')`` as ``lambda x: sin(x) + cos(x)``, where
``sin`` and ``cos`` come from the ``numpy`` namespace. This is also why
the symbols argument is first in ``lambdify``, as opposed to most SymPy
functions where it comes after the expression: to better mimic the
``lambda`` keyword.
``lambdify`` takes the input expression (like ``sin(x) + cos(x)``) and
1. Converts it to a string
2. Creates a module globals dictionary based on the modules that are
passed in (by default, it uses the NumPy module)
3. Creates the string ``"def func({vars}): return {expr}"``, where ``{vars}`` is the
list of variables separated by commas, and ``{expr}`` is the string
created in step 1., then ``exec``s that string with the module globals
namespace and returns ``func``.
In fact, functions returned by ``lambdify`` support inspection. So you can
see exactly how they are defined by using ``inspect.getsource``, or ``??`` if you
are using IPython or the Jupyter notebook.
>>> f = lambdify(x, sin(x) + cos(x))
>>> import inspect
>>> print(inspect.getsource(f))
def _lambdifygenerated(x):
return (sin(x) + cos(x))
This shows us the source code of the function, but not the namespace it
was defined in. We can inspect that by looking at the ``__globals__``
attribute of ``f``:
>>> f.__globals__['sin']
<ufunc 'sin'>
>>> f.__globals__['cos']
<ufunc 'cos'>
>>> f.__globals__['sin'] is numpy.sin
True
This shows us that ``sin`` and ``cos`` in the namespace of ``f`` will be
``numpy.sin`` and ``numpy.cos``.
Note that there are some convenience layers in each of these steps, but at
the core, this is how ``lambdify`` works. Step 1 is done using the
``LambdaPrinter`` printers defined in the printing module (see
:mod:`sympy.printing.lambdarepr`). This allows different SymPy expressions
to define how they should be converted to a string for different modules.
You can change which printer ``lambdify`` uses by passing a custom printer
in to the ``printer`` argument.
Step 2 is augmented by certain translations. There are default
translations for each module, but you can provide your own by passing a
list to the ``modules`` argument. For instance,
>>> def mysin(x):
... print('taking the sin of', x)
... return numpy.sin(x)
...
>>> f = lambdify(x, sin(x), [{'sin': mysin}, 'numpy'])
>>> f(1)
taking the sin of 1
0.8414709848078965
The globals dictionary is generated from the list by merging the
dictionary ``{'sin': mysin}`` and the module dictionary for NumPy. The
merging is done so that earlier items take precedence, which is why
``mysin`` is used above instead of ``numpy.sin``.
If you want to modify the way ``lambdify`` works for a given function, it
is usually easiest to do so by modifying the globals dictionary as such.
In more complicated cases, it may be necessary to create and pass in a
custom printer.
Finally, step 3 is augmented with certain convenience operations, such as
the addition of a docstring.
Understanding how ``lambdify`` works can make it easier to avoid certain
gotchas when using it. For instance, a common mistake is to create a
lambdified function for one module (say, NumPy), and pass it objects from
another (say, a SymPy expression).
For instance, say we create
>>> from sympy.abc import x
>>> f = lambdify(x, x + 1, 'numpy')
Now if we pass in a NumPy array, we get that array plus 1
>>> import numpy
>>> a = numpy.array([1, 2])
>>> f(a)
[2 3]
But what happens if you make the mistake of passing in a SymPy expression
instead of a NumPy array:
>>> f(x + 1)
x + 2
This worked, but it was only by accident. Now take a different lambdified
function:
>>> from sympy import sin
>>> g = lambdify(x, x + sin(x), 'numpy')
This works as expected on NumPy arrays:
>>> g(a)
[1.84147098 2.90929743]
But if we try to pass in a SymPy expression, it fails
>>> try:
... g(x + 1)
... # NumPy release after 1.17 raises TypeError instead of
... # AttributeError
... except (AttributeError, TypeError):
... raise AttributeError() # doctest: +IGNORE_EXCEPTION_DETAIL
Traceback (most recent call last):
...
AttributeError:
Now, let's look at what happened. The reason this fails is that ``g``
calls ``numpy.sin`` on the input expression, and ``numpy.sin`` does not
know how to operate on a SymPy object. **As a general rule, NumPy
functions do not know how to operate on SymPy expressions, and SymPy
functions do not know how to operate on NumPy arrays. This is why lambdify
exists: to provide a bridge between SymPy and NumPy.**
However, why is it that ``f`` did work? That's because ``f`` doesn't call
any functions, it only adds 1. So the resulting function that is created,
``def _lambdifygenerated(x): return x + 1`` does not depend on the globals
namespace it is defined in. Thus it works, but only by accident. A future
version of ``lambdify`` may remove this behavior.
Be aware that certain implementation details described here may change in
future versions of SymPy. The API of passing in custom modules and
printers will not change, but the details of how a lambda function is
created may change. However, the basic idea will remain the same, and
understanding it will be helpful to understanding the behavior of
lambdify.
**In general: you should create lambdified functions for one module (say,
NumPy), and only pass it input types that are compatible with that module
(say, NumPy arrays).** Remember that by default, if the ``module``
argument is not provided, ``lambdify`` creates functions using the NumPy
and SciPy namespaces.
"""
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 = ["numpy", "scipy"]
# 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 = {} # type: Dict[str, Any]
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 # type: ignore
elif _module_present('scipy', namespaces):
from sympy.printing.numpy import SciPyPrinter as Printer # type: ignore
elif _module_present('numpy', namespaces):
from sympy.printing.numpy import NumPyPrinter as Printer # type: ignore
elif _module_present('cupy', namespaces):
from sympy.printing.numpy import CuPyPrinter as Printer # type: ignore
elif _module_present('numexpr', namespaces):
from sympy.printing.lambdarepr import NumExprPrinter as Printer # type: ignore
elif _module_present('tensorflow', namespaces):
from sympy.printing.tensorflow import TensorflowPrinter as Printer # type: ignore
elif _module_present('sympy', namespaces):
from sympy.printing.pycode import SymPyPrinter as Printer # type: ignore
else:
from sympy.printing.pycode import PythonCodePrinter as Printer # type: ignore
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})
if isinstance(args, set):
SymPyDeprecationWarning(
feature="The list of arguments is a `set`. This leads to unpredictable results",
useinstead=": Convert set into list or tuple",
issue=20013,
deprecated_since_version="1.6.3"
).warn()
# 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() # type: ignore
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))
# Create the function definition code and execute it
funcname = '_lambdifygenerated'
if _module_present('tensorflow', namespaces):
funcprinter = _TensorflowEvaluatorPrinter(printer, dummify) # type: _EvaluatorPrinter
else:
funcprinter = _EvaluatorPrinter(printer, dummify)
if cse == True:
from sympy.simplify.cse_main import cse
cses, _expr = cse(expr, list=False)
elif callable(cse):
cses, _expr = cse(expr)
else:
cses, _expr = (), expr
funcstr = funcprinter.doprint(funcname, args, _expr, cses=cses)
# Collect the module imports from the code printers.
imp_mod_lines = []
for mod, keys in (getattr(printer, 'module_imports', None) or {}).items():
for k in keys:
if k not in namespace:
ln = "from %s import %s" % (mod, k)
try:
exec(ln, {}, namespace)
except ImportError:
# Tensorflow 2.0 has issues with importing a specific
# function from its submodule.
# https://github.com/tensorflow/tensorflow/issues/33022
ln = "%s = %s.%s" % (k, mod, k)
exec(ln, {}, namespace)
imp_mod_lines.append(ln)
# Provide lambda expression with builtins, and compatible implementation of range
namespace.update({'builtins':builtins, 'range':range})
funclocals = {} # type: Dict[str, Any]
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) # type: ignore
func = funclocals[funcname]
# Apply the docstring
sig = "func({})".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, str):
_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):
expr = sympify(expr)
# dict/tuple are sympified to Basic
if isinstance(expr, Basic):
expr = expr.xreplace(dummies_dict)
# list is not sympified to Basic
elif isinstance(expr, list):
expr = [sub_expr(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:
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, *, cses=()):
"""
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.extend(['{} = {}'.format(s, self._exprrepr(e)) for s, e in cses])
str_expr = self._exprrepr(expr)
if '\n' in str_expr:
str_expr = '({})'.format(str_expr)
funcbody.append('return {}'.format(str_expr))
funclines = [funcsig]
funclines.extend(' ' + line for line in funcbody)
return '\n'.join(funclines) + '\n'
@classmethod
def _is_safe_ident(cls, ident):
return isinstance(ident, str) and ident.isidentifier() \
and not keyword.iskeyword(ident)
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
from sympy.core.symbol import uniquely_named_symbol
from sympy.core.expr import Expr
# 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()
if isinstance(expr, Expr):
dummy = uniquely_named_symbol(
dummy.name, expr, modify=lambda s: '_' + s)
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
expr = sympify(expr)
xreplace = getattr(expr, 'xreplace', None)
if xreplace is not None:
expr = xreplace(dummies_dict)
else:
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
>>> 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
kwargs = {}
if isinstance(symfunc, UndefinedFunction):
kwargs = symfunc._kwargs
symfunc = symfunc.__name__
if isinstance(symfunc, str):
# Keyword arguments to UndefinedFunction are added as attributes to
# the created class.
symfunc = UndefinedFunction(
symfunc, _imp_=staticmethod(implementation), **kwargs)
elif not isinstance(symfunc, UndefinedFunction):
raise ValueError(filldedent('''
symfunc should be either a string or
an UndefinedFunction instance.'''))
return symfunc
|
0614708066b33ba664a3f9fcd31ed826aa474419f8b9dcd78a6b8a1bbbcbef9b | from collections import defaultdict, OrderedDict
from itertools import (
combinations, combinations_with_replacement, permutations,
product, product as cartes
)
import random
from operator import gt
from sympy.core import Basic
# this is the logical location of these functions
from sympy.core.compatibility import (as_int, is_sequence, iterable, ordered)
from sympy.core.compatibility import default_sort_key # noqa: F401
import sympy
from sympy.utilities.enumerative import (
multiset_partitions_taocp, list_visitor, MultisetPartitionTraverser)
def is_palindromic(s, i=0, j=None):
"""return True if the sequence is the same from left to right as it
is from right to left in the whole sequence (default) or in the
Python slice ``s[i: j]``; else False.
Examples
========
>>> from sympy.utilities.iterables import is_palindromic
>>> is_palindromic([1, 0, 1])
True
>>> is_palindromic('abcbb')
False
>>> is_palindromic('abcbb', 1)
False
Normal Python slicing is performed in place so there is no need to
create a slice of the sequence for testing:
>>> is_palindromic('abcbb', 1, -1)
True
>>> is_palindromic('abcbb', -4, -1)
True
See Also
========
sympy.ntheory.digits.is_palindromic: tests integers
"""
i, j, _ = slice(i, j).indices(len(s))
m = (j - i)//2
# if length is odd, middle element will be ignored
return all(s[i + k] == s[j - 1 - k] for k in range(m))
def flatten(iterable, levels=None, cls=None):
"""
Recursively denest iterable containers.
>>> from sympy.utilities.iterables import flatten
>>> flatten([1, 2, 3])
[1, 2, 3]
>>> flatten([1, 2, [3]])
[1, 2, 3]
>>> flatten([1, [2, 3], [4, 5]])
[1, 2, 3, 4, 5]
>>> flatten([1.0, 2, (1, None)])
[1.0, 2, 1, None]
If you want to denest only a specified number of levels of
nested containers, then set ``levels`` flag to the desired
number of levels::
>>> ls = [[(-2, -1), (1, 2)], [(0, 0)]]
>>> flatten(ls, levels=1)
[(-2, -1), (1, 2), (0, 0)]
If cls argument is specified, it will only flatten instances of that
class, for example:
>>> from sympy.core import Basic
>>> class MyOp(Basic):
... pass
...
>>> flatten([MyOp(1, MyOp(2, 3))], cls=MyOp)
[1, 2, 3]
adapted from https://kogs-www.informatik.uni-hamburg.de/~meine/python_tricks
"""
from sympy.tensor.array import NDimArray
if levels is not None:
if not levels:
return iterable
elif levels > 0:
levels -= 1
else:
raise ValueError(
"expected non-negative number of levels, got %s" % levels)
if cls is None:
reducible = lambda x: is_sequence(x, set)
else:
reducible = lambda x: isinstance(x, cls)
result = []
for el in iterable:
if reducible(el):
if hasattr(el, 'args') and not isinstance(el, NDimArray):
el = el.args
result.extend(flatten(el, levels=levels, cls=cls))
else:
result.append(el)
return result
def unflatten(iter, n=2):
"""Group ``iter`` into tuples of length ``n``. Raise an error if
the length of ``iter`` is not a multiple of ``n``.
"""
if n < 1 or len(iter) % n:
raise ValueError('iter length is not a multiple of %i' % n)
return list(zip(*(iter[i::n] for i in range(n))))
def reshape(seq, how):
"""Reshape the sequence according to the template in ``how``.
Examples
========
>>> from sympy.utilities import reshape
>>> seq = list(range(1, 9))
>>> reshape(seq, [4]) # lists of 4
[[1, 2, 3, 4], [5, 6, 7, 8]]
>>> reshape(seq, (4,)) # tuples of 4
[(1, 2, 3, 4), (5, 6, 7, 8)]
>>> reshape(seq, (2, 2)) # tuples of 4
[(1, 2, 3, 4), (5, 6, 7, 8)]
>>> reshape(seq, (2, [2])) # (i, i, [i, i])
[(1, 2, [3, 4]), (5, 6, [7, 8])]
>>> reshape(seq, ((2,), [2])) # etc....
[((1, 2), [3, 4]), ((5, 6), [7, 8])]
>>> reshape(seq, (1, [2], 1))
[(1, [2, 3], 4), (5, [6, 7], 8)]
>>> reshape(tuple(seq), ([[1], 1, (2,)],))
(([[1], 2, (3, 4)],), ([[5], 6, (7, 8)],))
>>> reshape(tuple(seq), ([1], 1, (2,)))
(([1], 2, (3, 4)), ([5], 6, (7, 8)))
>>> reshape(list(range(12)), [2, [3], {2}, (1, (3,), 1)])
[[0, 1, [2, 3, 4], {5, 6}, (7, (8, 9, 10), 11)]]
"""
m = sum(flatten(how))
n, rem = divmod(len(seq), m)
if m < 0 or rem:
raise ValueError('template must sum to positive number '
'that divides the length of the sequence')
i = 0
container = type(how)
rv = [None]*n
for k in range(len(rv)):
rv[k] = []
for hi in how:
if type(hi) is int:
rv[k].extend(seq[i: i + hi])
i += hi
else:
n = sum(flatten(hi))
hi_type = type(hi)
rv[k].append(hi_type(reshape(seq[i: i + n], hi)[0]))
i += n
rv[k] = container(rv[k])
return type(seq)(rv)
def group(seq, multiple=True):
"""
Splits a sequence into a list of lists of equal, adjacent elements.
Examples
========
>>> from sympy.utilities.iterables import group
>>> group([1, 1, 1, 2, 2, 3])
[[1, 1, 1], [2, 2], [3]]
>>> group([1, 1, 1, 2, 2, 3], multiple=False)
[(1, 3), (2, 2), (3, 1)]
>>> group([1, 1, 3, 2, 2, 1], multiple=False)
[(1, 2), (3, 1), (2, 2), (1, 1)]
See Also
========
multiset
"""
if not seq:
return []
current, groups = [seq[0]], []
for elem in seq[1:]:
if elem == current[-1]:
current.append(elem)
else:
groups.append(current)
current = [elem]
groups.append(current)
if multiple:
return groups
for i, current in enumerate(groups):
groups[i] = (current[0], len(current))
return groups
def _iproduct2(iterable1, iterable2):
'''Cartesian product of two possibly infinite iterables'''
it1 = iter(iterable1)
it2 = iter(iterable2)
elems1 = []
elems2 = []
sentinel = object()
def append(it, elems):
e = next(it, sentinel)
if e is not sentinel:
elems.append(e)
n = 0
append(it1, elems1)
append(it2, elems2)
while n <= len(elems1) + len(elems2):
for m in range(n-len(elems1)+1, len(elems2)):
yield (elems1[n-m], elems2[m])
n += 1
append(it1, elems1)
append(it2, elems2)
def iproduct(*iterables):
'''
Cartesian product of iterables.
Generator of the cartesian product of iterables. This is analogous to
itertools.product except that it works with infinite iterables and will
yield any item from the infinite product eventually.
Examples
========
>>> from sympy.utilities.iterables import iproduct
>>> sorted(iproduct([1,2], [3,4]))
[(1, 3), (1, 4), (2, 3), (2, 4)]
With an infinite iterator:
>>> from sympy import S
>>> (3,) in iproduct(S.Integers)
True
>>> (3, 4) in iproduct(S.Integers, S.Integers)
True
.. seealso::
`itertools.product <https://docs.python.org/3/library/itertools.html#itertools.product>`_
'''
if len(iterables) == 0:
yield ()
return
elif len(iterables) == 1:
for e in iterables[0]:
yield (e,)
elif len(iterables) == 2:
yield from _iproduct2(*iterables)
else:
first, others = iterables[0], iterables[1:]
for ef, eo in _iproduct2(first, iproduct(*others)):
yield (ef,) + eo
def multiset(seq):
"""Return the hashable sequence in multiset form with values being the
multiplicity of the item in the sequence.
Examples
========
>>> from sympy.utilities.iterables import multiset
>>> multiset('mississippi')
{'i': 4, 'm': 1, 'p': 2, 's': 4}
See Also
========
group
"""
rv = defaultdict(int)
for s in seq:
rv[s] += 1
return dict(rv)
def postorder_traversal(node, keys=None):
"""
Do a postorder traversal of a tree.
This generator recursively yields nodes that it has visited in a postorder
fashion. That is, it descends through the tree depth-first to yield all of
a node's children's postorder traversal before yielding the node itself.
Parameters
==========
node : sympy expression
The expression to traverse.
keys : (default None) sort key(s)
The key(s) used to sort args of Basic objects. When None, args of Basic
objects are processed in arbitrary order. If key is defined, it will
be passed along to ordered() as the only key(s) to use to sort the
arguments; if ``key`` is simply True then the default keys of
``ordered`` will be used (node count and default_sort_key).
Yields
======
subtree : sympy expression
All of the subtrees in the tree.
Examples
========
>>> from sympy.utilities.iterables import postorder_traversal
>>> from sympy.abc import w, x, y, z
The nodes are returned in the order that they are encountered unless key
is given; simply passing key=True will guarantee that the traversal is
unique.
>>> list(postorder_traversal(w + (x + y)*z)) # doctest: +SKIP
[z, y, x, x + y, z*(x + y), w, w + z*(x + y)]
>>> list(postorder_traversal(w + (x + y)*z, keys=True))
[w, z, x, y, x + y, z*(x + y), w + z*(x + y)]
"""
if isinstance(node, Basic):
args = node.args
if keys:
if keys != True:
args = ordered(args, keys, default=False)
else:
args = ordered(args)
for arg in args:
yield from postorder_traversal(arg, keys)
elif iterable(node):
for item in node:
yield from postorder_traversal(item, keys)
yield node
def interactive_traversal(expr):
"""Traverse a tree asking a user which branch to choose. """
from sympy.printing import pprint
RED, BRED = '\033[0;31m', '\033[1;31m'
GREEN, BGREEN = '\033[0;32m', '\033[1;32m'
YELLOW, BYELLOW = '\033[0;33m', '\033[1;33m' # noqa
BLUE, BBLUE = '\033[0;34m', '\033[1;34m' # noqa
MAGENTA, BMAGENTA = '\033[0;35m', '\033[1;35m'# noqa
CYAN, BCYAN = '\033[0;36m', '\033[1;36m' # noqa
END = '\033[0m'
def cprint(*args):
print("".join(map(str, args)) + END)
def _interactive_traversal(expr, stage):
if stage > 0:
print()
cprint("Current expression (stage ", BYELLOW, stage, END, "):")
print(BCYAN)
pprint(expr)
print(END)
if isinstance(expr, Basic):
if expr.is_Add:
args = expr.as_ordered_terms()
elif expr.is_Mul:
args = expr.as_ordered_factors()
else:
args = expr.args
elif hasattr(expr, "__iter__"):
args = list(expr)
else:
return expr
n_args = len(args)
if not n_args:
return expr
for i, arg in enumerate(args):
cprint(GREEN, "[", BGREEN, i, GREEN, "] ", BLUE, type(arg), END)
pprint(arg)
print()
if n_args == 1:
choices = '0'
else:
choices = '0-%d' % (n_args - 1)
try:
choice = input("Your choice [%s,f,l,r,d,?]: " % choices)
except EOFError:
result = expr
print()
else:
if choice == '?':
cprint(RED, "%s - select subexpression with the given index" %
choices)
cprint(RED, "f - select the first subexpression")
cprint(RED, "l - select the last subexpression")
cprint(RED, "r - select a random subexpression")
cprint(RED, "d - done\n")
result = _interactive_traversal(expr, stage)
elif choice in ['d', '']:
result = expr
elif choice == 'f':
result = _interactive_traversal(args[0], stage + 1)
elif choice == 'l':
result = _interactive_traversal(args[-1], stage + 1)
elif choice == 'r':
result = _interactive_traversal(random.choice(args), stage + 1)
else:
try:
choice = int(choice)
except ValueError:
cprint(BRED,
"Choice must be a number in %s range\n" % choices)
result = _interactive_traversal(expr, stage)
else:
if choice < 0 or choice >= n_args:
cprint(BRED, "Choice must be in %s range\n" % choices)
result = _interactive_traversal(expr, stage)
else:
result = _interactive_traversal(args[choice], stage + 1)
return result
return _interactive_traversal(expr, 0)
def ibin(n, bits=None, str=False):
"""Return a list of length ``bits`` corresponding to the binary value
of ``n`` with small bits to the right (last). If bits is omitted, the
length will be the number required to represent ``n``. If the bits are
desired in reversed order, use the ``[::-1]`` slice of the returned list.
If a sequence of all bits-length lists starting from ``[0, 0,..., 0]``
through ``[1, 1, ..., 1]`` are desired, pass a non-integer for bits, e.g.
``'all'``.
If the bit *string* is desired pass ``str=True``.
Examples
========
>>> from sympy.utilities.iterables import ibin
>>> ibin(2)
[1, 0]
>>> ibin(2, 4)
[0, 0, 1, 0]
If all lists corresponding to 0 to 2**n - 1, pass a non-integer
for bits:
>>> bits = 2
>>> for i in ibin(2, 'all'):
... print(i)
(0, 0)
(0, 1)
(1, 0)
(1, 1)
If a bit string is desired of a given length, use str=True:
>>> n = 123
>>> bits = 10
>>> ibin(n, bits, str=True)
'0001111011'
>>> ibin(n, bits, str=True)[::-1] # small bits left
'1101111000'
>>> list(ibin(3, 'all', str=True))
['000', '001', '010', '011', '100', '101', '110', '111']
"""
if n < 0:
raise ValueError("negative numbers are not allowed")
n = as_int(n)
if bits is None:
bits = 0
else:
try:
bits = as_int(bits)
except ValueError:
bits = -1
else:
if n.bit_length() > bits:
raise ValueError(
"`bits` must be >= {}".format(n.bit_length()))
if not str:
if bits >= 0:
return [1 if i == "1" else 0 for i in bin(n)[2:].rjust(bits, "0")]
else:
return variations(list(range(2)), n, repetition=True)
else:
if bits >= 0:
return bin(n)[2:].rjust(bits, "0")
else:
return (bin(i)[2:].rjust(n, "0") for i in range(2**n))
def variations(seq, n, repetition=False):
r"""Returns a generator of the n-sized variations of ``seq`` (size N).
``repetition`` controls whether items in ``seq`` can appear more than once;
Examples
========
``variations(seq, n)`` will return `\frac{N!}{(N - n)!}` permutations without
repetition of ``seq``'s elements:
>>> from sympy.utilities.iterables import variations
>>> list(variations([1, 2], 2))
[(1, 2), (2, 1)]
``variations(seq, n, True)`` will return the `N^n` permutations obtained
by allowing repetition of elements:
>>> list(variations([1, 2], 2, repetition=True))
[(1, 1), (1, 2), (2, 1), (2, 2)]
If you ask for more items than are in the set you get the empty set unless
you allow repetitions:
>>> list(variations([0, 1], 3, repetition=False))
[]
>>> list(variations([0, 1], 3, repetition=True))[:4]
[(0, 0, 0), (0, 0, 1), (0, 1, 0), (0, 1, 1)]
.. seealso::
`itertools.permutations <https://docs.python.org/3/library/itertools.html#itertools.permutations>`_,
`itertools.product <https://docs.python.org/3/library/itertools.html#itertools.product>`_
"""
if not repetition:
seq = tuple(seq)
if len(seq) < n:
return
yield from permutations(seq, n)
else:
if n == 0:
yield ()
else:
yield from product(seq, repeat=n)
def subsets(seq, k=None, repetition=False):
r"""Generates all `k`-subsets (combinations) from an `n`-element set, ``seq``.
A `k`-subset of an `n`-element set is any subset of length exactly `k`. The
number of `k`-subsets of an `n`-element set is given by ``binomial(n, k)``,
whereas there are `2^n` subsets all together. If `k` is ``None`` then all
`2^n` subsets will be returned from shortest to longest.
Examples
========
>>> from sympy.utilities.iterables import subsets
``subsets(seq, k)`` will return the `\frac{n!}{k!(n - k)!}` `k`-subsets (combinations)
without repetition, i.e. once an item has been removed, it can no
longer be "taken":
>>> list(subsets([1, 2], 2))
[(1, 2)]
>>> list(subsets([1, 2]))
[(), (1,), (2,), (1, 2)]
>>> list(subsets([1, 2, 3], 2))
[(1, 2), (1, 3), (2, 3)]
``subsets(seq, k, repetition=True)`` will return the `\frac{(n - 1 + k)!}{k!(n - 1)!}`
combinations *with* repetition:
>>> list(subsets([1, 2], 2, repetition=True))
[(1, 1), (1, 2), (2, 2)]
If you ask for more items than are in the set you get the empty set unless
you allow repetitions:
>>> list(subsets([0, 1], 3, repetition=False))
[]
>>> list(subsets([0, 1], 3, repetition=True))
[(0, 0, 0), (0, 0, 1), (0, 1, 1), (1, 1, 1)]
"""
if k is None:
for k in range(len(seq) + 1):
yield from subsets(seq, k, repetition)
else:
if not repetition:
yield from combinations(seq, k)
else:
yield from combinations_with_replacement(seq, k)
def filter_symbols(iterator, exclude):
"""
Only yield elements from `iterator` that do not occur in `exclude`.
Parameters
==========
iterator : iterable
iterator to take elements from
exclude : iterable
elements to exclude
Returns
=======
iterator : iterator
filtered iterator
"""
exclude = set(exclude)
for s in iterator:
if s not in exclude:
yield s
def numbered_symbols(prefix='x', cls=None, start=0, exclude=[], *args, **assumptions):
"""
Generate an infinite stream of Symbols consisting of a prefix and
increasing subscripts provided that they do not occur in ``exclude``.
Parameters
==========
prefix : str, optional
The prefix to use. By default, this function will generate symbols of
the form "x0", "x1", etc.
cls : class, optional
The class to use. By default, it uses ``Symbol``, but you can also use ``Wild`` or ``Dummy``.
start : int, optional
The start number. By default, it is 0.
Returns
=======
sym : Symbol
The subscripted symbols.
"""
exclude = set(exclude or [])
if cls is None:
# We can't just make the default cls=Symbol because it isn't
# imported yet.
from sympy import Symbol
cls = Symbol
while True:
name = '%s%s' % (prefix, start)
s = cls(name, *args, **assumptions)
if s not in exclude:
yield s
start += 1
def capture(func):
"""Return the printed output of func().
``func`` should be a function without arguments that produces output with
print statements.
>>> from sympy.utilities.iterables import capture
>>> from sympy import pprint
>>> from sympy.abc import x
>>> def foo():
... print('hello world!')
...
>>> 'hello' in capture(foo) # foo, not foo()
True
>>> capture(lambda: pprint(2/x))
'2\\n-\\nx\\n'
"""
from io import StringIO
import sys
stdout = sys.stdout
sys.stdout = file = StringIO()
try:
func()
finally:
sys.stdout = stdout
return file.getvalue()
def sift(seq, keyfunc, binary=False):
"""
Sift the sequence, ``seq`` according to ``keyfunc``.
Returns
=======
When ``binary`` is ``False`` (default), the output is a dictionary
where elements of ``seq`` are stored in a list keyed to the value
of keyfunc for that element. If ``binary`` is True then a tuple
with lists ``T`` and ``F`` are returned where ``T`` is a list
containing elements of seq for which ``keyfunc`` was ``True`` and
``F`` containing those elements for which ``keyfunc`` was ``False``;
a ValueError is raised if the ``keyfunc`` is not binary.
Examples
========
>>> from sympy.utilities import sift
>>> from sympy.abc import x, y
>>> from sympy import sqrt, exp, pi, Tuple
>>> sift(range(5), lambda x: x % 2)
{0: [0, 2, 4], 1: [1, 3]}
sift() returns a defaultdict() object, so any key that has no matches will
give [].
>>> sift([x], lambda x: x.is_commutative)
{True: [x]}
>>> _[False]
[]
Sometimes you will not know how many keys you will get:
>>> sift([sqrt(x), exp(x), (y**x)**2],
... lambda x: x.as_base_exp()[0])
{E: [exp(x)], x: [sqrt(x)], y: [y**(2*x)]}
Sometimes you expect the results to be binary; the
results can be unpacked by setting ``binary`` to True:
>>> sift(range(4), lambda x: x % 2, binary=True)
([1, 3], [0, 2])
>>> sift(Tuple(1, pi), lambda x: x.is_rational, binary=True)
([1], [pi])
A ValueError is raised if the predicate was not actually binary
(which is a good test for the logic where sifting is used and
binary results were expected):
>>> unknown = exp(1) - pi # the rationality of this is unknown
>>> args = Tuple(1, pi, unknown)
>>> sift(args, lambda x: x.is_rational, binary=True)
Traceback (most recent call last):
...
ValueError: keyfunc gave non-binary output
The non-binary sifting shows that there were 3 keys generated:
>>> set(sift(args, lambda x: x.is_rational).keys())
{None, False, True}
If you need to sort the sifted items it might be better to use
``ordered`` which can economically apply multiple sort keys
to a sequence while sorting.
See Also
========
ordered
"""
if not binary:
m = defaultdict(list)
for i in seq:
m[keyfunc(i)].append(i)
return m
sift = F, T = [], []
for i in seq:
try:
sift[keyfunc(i)].append(i)
except (IndexError, TypeError):
raise ValueError('keyfunc gave non-binary output')
return T, F
def take(iter, n):
"""Return ``n`` items from ``iter`` iterator. """
return [ value for _, value in zip(range(n), iter) ]
def dict_merge(*dicts):
"""Merge dictionaries into a single dictionary. """
merged = {}
for dict in dicts:
merged.update(dict)
return merged
def common_prefix(*seqs):
"""Return the subsequence that is a common start of sequences in ``seqs``.
>>> from sympy.utilities.iterables import common_prefix
>>> common_prefix(list(range(3)))
[0, 1, 2]
>>> common_prefix(list(range(3)), list(range(4)))
[0, 1, 2]
>>> common_prefix([1, 2, 3], [1, 2, 5])
[1, 2]
>>> common_prefix([1, 2, 3], [1, 3, 5])
[1]
"""
if any(not s for s in seqs):
return []
elif len(seqs) == 1:
return seqs[0]
i = 0
for i in range(min(len(s) for s in seqs)):
if not all(seqs[j][i] == seqs[0][i] for j in range(len(seqs))):
break
else:
i += 1
return seqs[0][:i]
def common_suffix(*seqs):
"""Return the subsequence that is a common ending of sequences in ``seqs``.
>>> from sympy.utilities.iterables import common_suffix
>>> common_suffix(list(range(3)))
[0, 1, 2]
>>> common_suffix(list(range(3)), list(range(4)))
[]
>>> common_suffix([1, 2, 3], [9, 2, 3])
[2, 3]
>>> common_suffix([1, 2, 3], [9, 7, 3])
[3]
"""
if any(not s for s in seqs):
return []
elif len(seqs) == 1:
return seqs[0]
i = 0
for i in range(-1, -min(len(s) for s in seqs) - 1, -1):
if not all(seqs[j][i] == seqs[0][i] for j in range(len(seqs))):
break
else:
i -= 1
if i == -1:
return []
else:
return seqs[0][i + 1:]
def prefixes(seq):
"""
Generate all prefixes of a sequence.
Examples
========
>>> from sympy.utilities.iterables import prefixes
>>> list(prefixes([1,2,3,4]))
[[1], [1, 2], [1, 2, 3], [1, 2, 3, 4]]
"""
n = len(seq)
for i in range(n):
yield seq[:i + 1]
def postfixes(seq):
"""
Generate all postfixes of a sequence.
Examples
========
>>> from sympy.utilities.iterables import postfixes
>>> list(postfixes([1,2,3,4]))
[[4], [3, 4], [2, 3, 4], [1, 2, 3, 4]]
"""
n = len(seq)
for i in range(n):
yield seq[n - i - 1:]
def topological_sort(graph, key=None):
r"""
Topological sort of graph's vertices.
Parameters
==========
graph : tuple[list, list[tuple[T, T]]
A tuple consisting of a list of vertices and a list of edges of
a graph to be sorted topologically.
key : callable[T] (optional)
Ordering key for vertices on the same level. By default the natural
(e.g. lexicographic) ordering is used (in this case the base type
must implement ordering relations).
Examples
========
Consider a graph::
+---+ +---+ +---+
| 7 |\ | 5 | | 3 |
+---+ \ +---+ +---+
| _\___/ ____ _/ |
| / \___/ \ / |
V V V V |
+----+ +---+ |
| 11 | | 8 | |
+----+ +---+ |
| | \____ ___/ _ |
| \ \ / / \ |
V \ V V / V V
+---+ \ +---+ | +----+
| 2 | | | 9 | | | 10 |
+---+ | +---+ | +----+
\________/
where vertices are integers. This graph can be encoded using
elementary Python's data structures as follows::
>>> V = [2, 3, 5, 7, 8, 9, 10, 11]
>>> E = [(7, 11), (7, 8), (5, 11), (3, 8), (3, 10),
... (11, 2), (11, 9), (11, 10), (8, 9)]
To compute a topological sort for graph ``(V, E)`` issue::
>>> from sympy.utilities.iterables import topological_sort
>>> topological_sort((V, E))
[3, 5, 7, 8, 11, 2, 9, 10]
If specific tie breaking approach is needed, use ``key`` parameter::
>>> topological_sort((V, E), key=lambda v: -v)
[7, 5, 11, 3, 10, 8, 9, 2]
Only acyclic graphs can be sorted. If the input graph has a cycle,
then ``ValueError`` will be raised::
>>> topological_sort((V, E + [(10, 7)]))
Traceback (most recent call last):
...
ValueError: cycle detected
References
==========
.. [1] https://en.wikipedia.org/wiki/Topological_sorting
"""
V, E = graph
L = []
S = set(V)
E = list(E)
for v, u in E:
S.discard(u)
if key is None:
key = lambda value: value
S = sorted(S, key=key, reverse=True)
while S:
node = S.pop()
L.append(node)
for u, v in list(E):
if u == node:
E.remove((u, v))
for _u, _v in E:
if v == _v:
break
else:
kv = key(v)
for i, s in enumerate(S):
ks = key(s)
if kv > ks:
S.insert(i, v)
break
else:
S.append(v)
if E:
raise ValueError("cycle detected")
else:
return L
def strongly_connected_components(G):
r"""
Strongly connected components of a directed graph in reverse topological
order.
Parameters
==========
graph : tuple[list, list[tuple[T, T]]
A tuple consisting of a list of vertices and a list of edges of
a graph whose strongly connected components are to be found.
Examples
========
Consider a directed graph (in dot notation)::
digraph {
A -> B
A -> C
B -> C
C -> B
B -> D
}
where vertices are the letters A, B, C and D. This graph can be encoded
using Python's elementary data structures as follows::
>>> V = ['A', 'B', 'C', 'D']
>>> E = [('A', 'B'), ('A', 'C'), ('B', 'C'), ('C', 'B'), ('B', 'D')]
The strongly connected components of this graph can be computed as
>>> from sympy.utilities.iterables import strongly_connected_components
>>> strongly_connected_components((V, E))
[['D'], ['B', 'C'], ['A']]
This also gives the components in reverse topological order.
Since the subgraph containing B and C has a cycle they must be together in
a strongly connected component. A and D are connected to the rest of the
graph but not in a cyclic manner so they appear as their own strongly
connected components.
Notes
=====
The vertices of the graph must be hashable for the data structures used.
If the vertices are unhashable replace them with integer indices.
This function uses Tarjan's algorithm to compute the strongly connected
components in `O(|V|+|E|)` (linear) time.
References
==========
.. [1] https://en.wikipedia.org/wiki/Strongly_connected_component
.. [2] https://en.wikipedia.org/wiki/Tarjan%27s_strongly_connected_components_algorithm
See Also
========
sympy.utilities.iterables.connected_components
"""
# Map from a vertex to its neighbours
V, E = G
Gmap = {vi: [] for vi in V}
for v1, v2 in E:
Gmap[v1].append(v2)
return _strongly_connected_components(V, Gmap)
def _strongly_connected_components(V, Gmap):
"""More efficient internal routine for strongly_connected_components"""
#
# Here V is an iterable of vertices and Gmap is a dict mapping each vertex
# to a list of neighbours e.g.:
#
# V = [0, 1, 2, 3]
# Gmap = {0: [2, 3], 1: [0]}
#
# For a large graph these data structures can often be created more
# efficiently then those expected by strongly_connected_components() which
# in this case would be
#
# V = [0, 1, 2, 3]
# Gmap = [(0, 2), (0, 3), (1, 0)]
#
# XXX: Maybe this should be the recommended function to use instead...
#
# Non-recursive Tarjan's algorithm:
lowlink = {}
indices = {}
stack = OrderedDict()
callstack = []
components = []
nomore = object()
def start(v):
index = len(stack)
indices[v] = lowlink[v] = index
stack[v] = None
callstack.append((v, iter(Gmap[v])))
def finish(v1):
# Finished a component?
if lowlink[v1] == indices[v1]:
component = [stack.popitem()[0]]
while component[-1] is not v1:
component.append(stack.popitem()[0])
components.append(component[::-1])
v2, _ = callstack.pop()
if callstack:
v1, _ = callstack[-1]
lowlink[v1] = min(lowlink[v1], lowlink[v2])
for v in V:
if v in indices:
continue
start(v)
while callstack:
v1, it1 = callstack[-1]
v2 = next(it1, nomore)
# Finished children of v1?
if v2 is nomore:
finish(v1)
# Recurse on v2
elif v2 not in indices:
start(v2)
elif v2 in stack:
lowlink[v1] = min(lowlink[v1], indices[v2])
# Reverse topological sort order:
return components
def connected_components(G):
r"""
Connected components of an undirected graph or weakly connected components
of a directed graph.
Parameters
==========
graph : tuple[list, list[tuple[T, T]]
A tuple consisting of a list of vertices and a list of edges of
a graph whose connected components are to be found.
Examples
========
Given an undirected graph::
graph {
A -- B
C -- D
}
We can find the connected components using this function if we include
each edge in both directions::
>>> from sympy.utilities.iterables import connected_components
>>> V = ['A', 'B', 'C', 'D']
>>> E = [('A', 'B'), ('B', 'A'), ('C', 'D'), ('D', 'C')]
>>> connected_components((V, E))
[['A', 'B'], ['C', 'D']]
The weakly connected components of a directed graph can found the same
way.
Notes
=====
The vertices of the graph must be hashable for the data structures used.
If the vertices are unhashable replace them with integer indices.
This function uses Tarjan's algorithm to compute the connected components
in `O(|V|+|E|)` (linear) time.
References
==========
.. [1] https://en.wikipedia.org/wiki/Connected_component_(graph_theory)
.. [2] https://en.wikipedia.org/wiki/Tarjan%27s_strongly_connected_components_algorithm
See Also
========
sympy.utilities.iterables.strongly_connected_components
"""
# Duplicate edges both ways so that the graph is effectively undirected
# and return the strongly connected components:
V, E = G
E_undirected = []
for v1, v2 in E:
E_undirected.extend([(v1, v2), (v2, v1)])
return strongly_connected_components((V, E_undirected))
def rotate_left(x, y):
"""
Left rotates a list x by the number of steps specified
in y.
Examples
========
>>> from sympy.utilities.iterables import rotate_left
>>> a = [0, 1, 2]
>>> rotate_left(a, 1)
[1, 2, 0]
"""
if len(x) == 0:
return []
y = y % len(x)
return x[y:] + x[:y]
def rotate_right(x, y):
"""
Right rotates a list x by the number of steps specified
in y.
Examples
========
>>> from sympy.utilities.iterables import rotate_right
>>> a = [0, 1, 2]
>>> rotate_right(a, 1)
[2, 0, 1]
"""
if len(x) == 0:
return []
y = len(x) - y % len(x)
return x[y:] + x[:y]
def least_rotation(x, key=None):
'''
Returns the number of steps of left rotation required to
obtain lexicographically minimal string/list/tuple, etc.
Examples
========
>>> from sympy.utilities.iterables import least_rotation, rotate_left
>>> a = [3, 1, 5, 1, 2]
>>> least_rotation(a)
3
>>> rotate_left(a, _)
[1, 2, 3, 1, 5]
References
==========
.. [1] https://en.wikipedia.org/wiki/Lexicographically_minimal_string_rotation
'''
if key is None: key = sympy.Id
S = x + x # Concatenate string to it self to avoid modular arithmetic
f = [-1] * len(S) # Failure function
k = 0 # Least rotation of string found so far
for j in range(1,len(S)):
sj = S[j]
i = f[j-k-1]
while i != -1 and sj != S[k+i+1]:
if key(sj) < key(S[k+i+1]):
k = j-i-1
i = f[i]
if sj != S[k+i+1]:
if key(sj) < key(S[k]):
k = j
f[j-k] = -1
else:
f[j-k] = i+1
return k
def multiset_combinations(m, n, g=None):
"""
Return the unique combinations of size ``n`` from multiset ``m``.
Examples
========
>>> from sympy.utilities.iterables import multiset_combinations
>>> from itertools import combinations
>>> [''.join(i) for i in multiset_combinations('baby', 3)]
['abb', 'aby', 'bby']
>>> def count(f, s): return len(list(f(s, 3)))
The number of combinations depends on the number of letters; the
number of unique combinations depends on how the letters are
repeated.
>>> s1 = 'abracadabra'
>>> s2 = 'banana tree'
>>> count(combinations, s1), count(multiset_combinations, s1)
(165, 23)
>>> count(combinations, s2), count(multiset_combinations, s2)
(165, 54)
"""
if g is None:
if type(m) is dict:
if n > sum(m.values()):
return
g = [[k, m[k]] for k in ordered(m)]
else:
m = list(m)
if n > len(m):
return
try:
m = multiset(m)
g = [(k, m[k]) for k in ordered(m)]
except TypeError:
m = list(ordered(m))
g = [list(i) for i in group(m, multiple=False)]
del m
if sum(v for k, v in g) < n or not n:
yield []
else:
for i, (k, v) in enumerate(g):
if v >= n:
yield [k]*n
v = n - 1
for v in range(min(n, v), 0, -1):
for j in multiset_combinations(None, n - v, g[i + 1:]):
rv = [k]*v + j
if len(rv) == n:
yield rv
def multiset_permutations(m, size=None, g=None):
"""
Return the unique permutations of multiset ``m``.
Examples
========
>>> from sympy.utilities.iterables import multiset_permutations
>>> from sympy import factorial
>>> [''.join(i) for i in multiset_permutations('aab')]
['aab', 'aba', 'baa']
>>> factorial(len('banana'))
720
>>> len(list(multiset_permutations('banana')))
60
"""
if g is None:
if type(m) is dict:
g = [[k, m[k]] for k in ordered(m)]
else:
m = list(ordered(m))
g = [list(i) for i in group(m, multiple=False)]
del m
do = [gi for gi in g if gi[1] > 0]
SUM = sum([gi[1] for gi in do])
if not do or size is not None and (size > SUM or size < 1):
if size < 1:
yield []
return
elif size == 1:
for k, v in do:
yield [k]
elif len(do) == 1:
k, v = do[0]
v = v if size is None else (size if size <= v else 0)
yield [k for i in range(v)]
elif all(v == 1 for k, v in do):
for p in permutations([k for k, v in do], size):
yield list(p)
else:
size = size if size is not None else SUM
for i, (k, v) in enumerate(do):
do[i][1] -= 1
for j in multiset_permutations(None, size - 1, do):
if j:
yield [k] + j
do[i][1] += 1
def _partition(seq, vector, m=None):
"""
Return the partition of seq as specified by the partition vector.
Examples
========
>>> from sympy.utilities.iterables import _partition
>>> _partition('abcde', [1, 0, 1, 2, 0])
[['b', 'e'], ['a', 'c'], ['d']]
Specifying the number of bins in the partition is optional:
>>> _partition('abcde', [1, 0, 1, 2, 0], 3)
[['b', 'e'], ['a', 'c'], ['d']]
The output of _set_partitions can be passed as follows:
>>> output = (3, [1, 0, 1, 2, 0])
>>> _partition('abcde', *output)
[['b', 'e'], ['a', 'c'], ['d']]
See Also
========
combinatorics.partitions.Partition.from_rgs
"""
if m is None:
m = max(vector) + 1
elif type(vector) is int: # entered as m, vector
vector, m = m, vector
p = [[] for i in range(m)]
for i, v in enumerate(vector):
p[v].append(seq[i])
return p
def _set_partitions(n):
"""Cycle through all partions of n elements, yielding the
current number of partitions, ``m``, and a mutable list, ``q``
such that element[i] is in part q[i] of the partition.
NOTE: ``q`` is modified in place and generally should not be changed
between function calls.
Examples
========
>>> from sympy.utilities.iterables import _set_partitions, _partition
>>> for m, q in _set_partitions(3):
... print('%s %s %s' % (m, q, _partition('abc', q, m)))
1 [0, 0, 0] [['a', 'b', 'c']]
2 [0, 0, 1] [['a', 'b'], ['c']]
2 [0, 1, 0] [['a', 'c'], ['b']]
2 [0, 1, 1] [['a'], ['b', 'c']]
3 [0, 1, 2] [['a'], ['b'], ['c']]
Notes
=====
This algorithm is similar to, and solves the same problem as,
Algorithm 7.2.1.5H, from volume 4A of Knuth's The Art of Computer
Programming. Knuth uses the term "restricted growth string" where
this code refers to a "partition vector". In each case, the meaning is
the same: the value in the ith element of the vector specifies to
which part the ith set element is to be assigned.
At the lowest level, this code implements an n-digit big-endian
counter (stored in the array q) which is incremented (with carries) to
get the next partition in the sequence. A special twist is that a
digit is constrained to be at most one greater than the maximum of all
the digits to the left of it. The array p maintains this maximum, so
that the code can efficiently decide when a digit can be incremented
in place or whether it needs to be reset to 0 and trigger a carry to
the next digit. The enumeration starts with all the digits 0 (which
corresponds to all the set elements being assigned to the same 0th
part), and ends with 0123...n, which corresponds to each set element
being assigned to a different, singleton, part.
This routine was rewritten to use 0-based lists while trying to
preserve the beauty and efficiency of the original algorithm.
References
==========
.. [1] Nijenhuis, Albert and Wilf, Herbert. (1978) Combinatorial Algorithms,
2nd Ed, p 91, algorithm "nexequ". Available online from
https://www.math.upenn.edu/~wilf/website/CombAlgDownld.html (viewed
November 17, 2012).
"""
p = [0]*n
q = [0]*n
nc = 1
yield nc, q
while nc != n:
m = n
while 1:
m -= 1
i = q[m]
if p[i] != 1:
break
q[m] = 0
i += 1
q[m] = i
m += 1
nc += m - n
p[0] += n - m
if i == nc:
p[nc] = 0
nc += 1
p[i - 1] -= 1
p[i] += 1
yield nc, q
def multiset_partitions(multiset, m=None):
"""
Return unique partitions of the given multiset (in list form).
If ``m`` is None, all multisets will be returned, otherwise only
partitions with ``m`` parts will be returned.
If ``multiset`` is an integer, a range [0, 1, ..., multiset - 1]
will be supplied.
Examples
========
>>> from sympy.utilities.iterables import multiset_partitions
>>> list(multiset_partitions([1, 2, 3, 4], 2))
[[[1, 2, 3], [4]], [[1, 2, 4], [3]], [[1, 2], [3, 4]],
[[1, 3, 4], [2]], [[1, 3], [2, 4]], [[1, 4], [2, 3]],
[[1], [2, 3, 4]]]
>>> list(multiset_partitions([1, 2, 3, 4], 1))
[[[1, 2, 3, 4]]]
Only unique partitions are returned and these will be returned in a
canonical order regardless of the order of the input:
>>> a = [1, 2, 2, 1]
>>> ans = list(multiset_partitions(a, 2))
>>> a.sort()
>>> list(multiset_partitions(a, 2)) == ans
True
>>> a = range(3, 1, -1)
>>> (list(multiset_partitions(a)) ==
... list(multiset_partitions(sorted(a))))
True
If m is omitted then all partitions will be returned:
>>> list(multiset_partitions([1, 1, 2]))
[[[1, 1, 2]], [[1, 1], [2]], [[1, 2], [1]], [[1], [1], [2]]]
>>> list(multiset_partitions([1]*3))
[[[1, 1, 1]], [[1], [1, 1]], [[1], [1], [1]]]
Counting
========
The number of partitions of a set is given by the bell number:
>>> from sympy import bell
>>> len(list(multiset_partitions(5))) == bell(5) == 52
True
The number of partitions of length k from a set of size n is given by the
Stirling Number of the 2nd kind:
>>> from sympy.functions.combinatorial.numbers import stirling
>>> stirling(5, 2) == len(list(multiset_partitions(5, 2))) == 15
True
These comments on counting apply to *sets*, not multisets.
Notes
=====
When all the elements are the same in the multiset, the order
of the returned partitions is determined by the ``partitions``
routine. If one is counting partitions then it is better to use
the ``nT`` function.
See Also
========
partitions
sympy.combinatorics.partitions.Partition
sympy.combinatorics.partitions.IntegerPartition
sympy.functions.combinatorial.numbers.nT
"""
# This function looks at the supplied input and dispatches to
# several special-case routines as they apply.
if type(multiset) is int:
n = multiset
if m and m > n:
return
multiset = list(range(n))
if m == 1:
yield [multiset[:]]
return
# If m is not None, it can sometimes be faster to use
# MultisetPartitionTraverser.enum_range() even for inputs
# which are sets. Since the _set_partitions code is quite
# fast, this is only advantageous when the overall set
# partitions outnumber those with the desired number of parts
# by a large factor. (At least 60.) Such a switch is not
# currently implemented.
for nc, q in _set_partitions(n):
if m is None or nc == m:
rv = [[] for i in range(nc)]
for i in range(n):
rv[q[i]].append(multiset[i])
yield rv
return
if len(multiset) == 1 and isinstance(multiset, str):
multiset = [multiset]
if not has_variety(multiset):
# Only one component, repeated n times. The resulting
# partitions correspond to partitions of integer n.
n = len(multiset)
if m and m > n:
return
if m == 1:
yield [multiset[:]]
return
x = multiset[:1]
for size, p in partitions(n, m, size=True):
if m is None or size == m:
rv = []
for k in sorted(p):
rv.extend([x*k]*p[k])
yield rv
else:
multiset = list(ordered(multiset))
n = len(multiset)
if m and m > n:
return
if m == 1:
yield [multiset[:]]
return
# Split the information of the multiset into two lists -
# one of the elements themselves, and one (of the same length)
# giving the number of repeats for the corresponding element.
elements, multiplicities = zip(*group(multiset, False))
if len(elements) < len(multiset):
# General case - multiset with more than one distinct element
# and at least one element repeated more than once.
if m:
mpt = MultisetPartitionTraverser()
for state in mpt.enum_range(multiplicities, m-1, m):
yield list_visitor(state, elements)
else:
for state in multiset_partitions_taocp(multiplicities):
yield list_visitor(state, elements)
else:
# Set partitions case - no repeated elements. Pretty much
# same as int argument case above, with same possible, but
# currently unimplemented optimization for some cases when
# m is not None
for nc, q in _set_partitions(n):
if m is None or nc == m:
rv = [[] for i in range(nc)]
for i in range(n):
rv[q[i]].append(i)
yield [[multiset[j] for j in i] for i in rv]
def partitions(n, m=None, k=None, size=False):
"""Generate all partitions of positive integer, n.
Parameters
==========
m : integer (default gives partitions of all sizes)
limits number of parts in partition (mnemonic: m, maximum parts)
k : integer (default gives partitions number from 1 through n)
limits the numbers that are kept in the partition (mnemonic: k, keys)
size : bool (default False, only partition is returned)
when ``True`` then (M, P) is returned where M is the sum of the
multiplicities and P is the generated partition.
Each partition is represented as a dictionary, mapping an integer
to the number of copies of that integer in the partition. For example,
the first partition of 4 returned is {4: 1}, "4: one of them".
Examples
========
>>> from sympy.utilities.iterables import partitions
The numbers appearing in the partition (the key of the returned dict)
are limited with k:
>>> for p in partitions(6, k=2): # doctest: +SKIP
... print(p)
{2: 3}
{1: 2, 2: 2}
{1: 4, 2: 1}
{1: 6}
The maximum number of parts in the partition (the sum of the values in
the returned dict) are limited with m (default value, None, gives
partitions from 1 through n):
>>> for p in partitions(6, m=2): # doctest: +SKIP
... print(p)
...
{6: 1}
{1: 1, 5: 1}
{2: 1, 4: 1}
{3: 2}
References
==========
.. [1] modified from Tim Peter's version to allow for k and m values:
http://code.activestate.com/recipes/218332-generator-for-integer-partitions/
See Also
========
sympy.combinatorics.partitions.Partition
sympy.combinatorics.partitions.IntegerPartition
"""
if (n <= 0 or
m is not None and m < 1 or
k is not None and k < 1 or
m and k and m*k < n):
# the empty set is the only way to handle these inputs
# and returning {} to represent it is consistent with
# the counting convention, e.g. nT(0) == 1.
if size:
yield 0, {}
else:
yield {}
return
if m is None:
m = n
else:
m = min(m, n)
k = min(k or n, n)
n, m, k = as_int(n), as_int(m), as_int(k)
q, r = divmod(n, k)
ms = {k: q}
keys = [k] # ms.keys(), from largest to smallest
if r:
ms[r] = 1
keys.append(r)
room = m - q - bool(r)
if size:
yield sum(ms.values()), ms.copy()
else:
yield ms.copy()
while keys != [1]:
# Reuse any 1's.
if keys[-1] == 1:
del keys[-1]
reuse = ms.pop(1)
room += reuse
else:
reuse = 0
while 1:
# Let i be the smallest key larger than 1. Reuse one
# instance of i.
i = keys[-1]
newcount = ms[i] = ms[i] - 1
reuse += i
if newcount == 0:
del keys[-1], ms[i]
room += 1
# Break the remainder into pieces of size i-1.
i -= 1
q, r = divmod(reuse, i)
need = q + bool(r)
if need > room:
if not keys:
return
continue
ms[i] = q
keys.append(i)
if r:
ms[r] = 1
keys.append(r)
break
room -= need
if size:
yield sum(ms.values()), ms.copy()
else:
yield ms.copy()
def ordered_partitions(n, m=None, sort=True):
"""Generates ordered partitions of integer ``n``.
Parameters
==========
m : integer (default None)
The default value gives partitions of all sizes else only
those with size m. In addition, if ``m`` is not None then
partitions are generated *in place* (see examples).
sort : bool (default True)
Controls whether partitions are
returned in sorted order when ``m`` is not None; when False,
the partitions are returned as fast as possible with elements
sorted, but when m|n the partitions will not be in
ascending lexicographical order.
Examples
========
>>> from sympy.utilities.iterables import ordered_partitions
All partitions of 5 in ascending lexicographical:
>>> for p in ordered_partitions(5):
... print(p)
[1, 1, 1, 1, 1]
[1, 1, 1, 2]
[1, 1, 3]
[1, 2, 2]
[1, 4]
[2, 3]
[5]
Only partitions of 5 with two parts:
>>> for p in ordered_partitions(5, 2):
... print(p)
[1, 4]
[2, 3]
When ``m`` is given, a given list objects will be used more than
once for speed reasons so you will not see the correct partitions
unless you make a copy of each as it is generated:
>>> [p for p in ordered_partitions(7, 3)]
[[1, 1, 1], [1, 1, 1], [1, 1, 1], [2, 2, 2]]
>>> [list(p) for p in ordered_partitions(7, 3)]
[[1, 1, 5], [1, 2, 4], [1, 3, 3], [2, 2, 3]]
When ``n`` is a multiple of ``m``, the elements are still sorted
but the partitions themselves will be *unordered* if sort is False;
the default is to return them in ascending lexicographical order.
>>> for p in ordered_partitions(6, 2):
... print(p)
[1, 5]
[2, 4]
[3, 3]
But if speed is more important than ordering, sort can be set to
False:
>>> for p in ordered_partitions(6, 2, sort=False):
... print(p)
[1, 5]
[3, 3]
[2, 4]
References
==========
.. [1] Generating Integer Partitions, [online],
Available: https://jeromekelleher.net/generating-integer-partitions.html
.. [2] Jerome Kelleher and Barry O'Sullivan, "Generating All
Partitions: A Comparison Of Two Encodings", [online],
Available: https://arxiv.org/pdf/0909.2331v2.pdf
"""
if n < 1 or m is not None and m < 1:
# the empty set is the only way to handle these inputs
# and returning {} to represent it is consistent with
# the counting convention, e.g. nT(0) == 1.
yield []
return
if m is None:
# The list `a`'s leading elements contain the partition in which
# y is the biggest element and x is either the same as y or the
# 2nd largest element; v and w are adjacent element indices
# to which x and y are being assigned, respectively.
a = [1]*n
y = -1
v = n
while v > 0:
v -= 1
x = a[v] + 1
while y >= 2 * x:
a[v] = x
y -= x
v += 1
w = v + 1
while x <= y:
a[v] = x
a[w] = y
yield a[:w + 1]
x += 1
y -= 1
a[v] = x + y
y = a[v] - 1
yield a[:w]
elif m == 1:
yield [n]
elif n == m:
yield [1]*n
else:
# recursively generate partitions of size m
for b in range(1, n//m + 1):
a = [b]*m
x = n - b*m
if not x:
if sort:
yield a
elif not sort and x <= m:
for ax in ordered_partitions(x, sort=False):
mi = len(ax)
a[-mi:] = [i + b for i in ax]
yield a
a[-mi:] = [b]*mi
else:
for mi in range(1, m):
for ax in ordered_partitions(x, mi, sort=True):
a[-mi:] = [i + b for i in ax]
yield a
a[-mi:] = [b]*mi
def binary_partitions(n):
"""
Generates the binary partition of n.
A binary partition consists only of numbers that are
powers of two. Each step reduces a `2^{k+1}` to `2^k` and
`2^k`. Thus 16 is converted to 8 and 8.
Examples
========
>>> from sympy.utilities.iterables import binary_partitions
>>> for i in binary_partitions(5):
... print(i)
...
[4, 1]
[2, 2, 1]
[2, 1, 1, 1]
[1, 1, 1, 1, 1]
References
==========
.. [1] TAOCP 4, section 7.2.1.5, problem 64
"""
from math import ceil, log
pow = int(2**(ceil(log(n, 2))))
sum = 0
partition = []
while pow:
if sum + pow <= n:
partition.append(pow)
sum += pow
pow >>= 1
last_num = len(partition) - 1 - (n & 1)
while last_num >= 0:
yield partition
if partition[last_num] == 2:
partition[last_num] = 1
partition.append(1)
last_num -= 1
continue
partition.append(1)
partition[last_num] >>= 1
x = partition[last_num + 1] = partition[last_num]
last_num += 1
while x > 1:
if x <= len(partition) - last_num - 1:
del partition[-x + 1:]
last_num += 1
partition[last_num] = x
else:
x >>= 1
yield [1]*n
def has_dups(seq):
"""Return True if there are any duplicate elements in ``seq``.
Examples
========
>>> from sympy.utilities.iterables import has_dups
>>> from sympy import Dict, Set
>>> has_dups((1, 2, 1))
True
>>> has_dups(range(3))
False
>>> all(has_dups(c) is False for c in (set(), Set(), dict(), Dict()))
True
"""
from sympy.core.containers import Dict
from sympy.sets.sets import Set
if isinstance(seq, (dict, set, Dict, Set)):
return False
uniq = set()
return any(True for s in seq if s in uniq or uniq.add(s))
def has_variety(seq):
"""Return True if there are any different elements in ``seq``.
Examples
========
>>> from sympy.utilities.iterables import has_variety
>>> has_variety((1, 2, 1))
True
>>> has_variety((1, 1, 1))
False
"""
for i, s in enumerate(seq):
if i == 0:
sentinel = s
else:
if s != sentinel:
return True
return False
def uniq(seq, result=None):
"""
Yield unique elements from ``seq`` as an iterator. The second
parameter ``result`` is used internally; it is not necessary
to pass anything for this.
Note: changing the sequence during iteration will raise a
RuntimeError if the size of the sequence is known; if you pass
an iterator and advance the iterator you will change the
output of this routine but there will be no warning.
Examples
========
>>> from sympy.utilities.iterables import uniq
>>> dat = [1, 4, 1, 5, 4, 2, 1, 2]
>>> type(uniq(dat)) in (list, tuple)
False
>>> list(uniq(dat))
[1, 4, 5, 2]
>>> list(uniq(x for x in dat))
[1, 4, 5, 2]
>>> list(uniq([[1], [2, 1], [1]]))
[[1], [2, 1]]
"""
try:
n = len(seq)
except TypeError:
n = None
def check():
# check that size of seq did not change during iteration;
# if n == None the object won't support size changing, e.g.
# an iterator can't be changed
if n is not None and len(seq) != n:
raise RuntimeError('sequence changed size during iteration')
try:
seen = set()
result = result or []
for i, s in enumerate(seq):
if not (s in seen or seen.add(s)):
yield s
check()
except TypeError:
if s not in result:
yield s
check()
result.append(s)
if hasattr(seq, '__getitem__'):
yield from uniq(seq[i + 1:], result)
else:
yield from uniq(seq, result)
def generate_bell(n):
"""Return permutations of [0, 1, ..., n - 1] such that each permutation
differs from the last by the exchange of a single pair of neighbors.
The ``n!`` permutations are returned as an iterator. In order to obtain
the next permutation from a random starting permutation, use the
``next_trotterjohnson`` method of the Permutation class (which generates
the same sequence in a different manner).
Examples
========
>>> from itertools import permutations
>>> from sympy.utilities.iterables import generate_bell
>>> from sympy import zeros, Matrix
This is the sort of permutation used in the ringing of physical bells,
and does not produce permutations in lexicographical order. Rather, the
permutations differ from each other by exactly one inversion, and the
position at which the swapping occurs varies periodically in a simple
fashion. Consider the first few permutations of 4 elements generated
by ``permutations`` and ``generate_bell``:
>>> list(permutations(range(4)))[:5]
[(0, 1, 2, 3), (0, 1, 3, 2), (0, 2, 1, 3), (0, 2, 3, 1), (0, 3, 1, 2)]
>>> list(generate_bell(4))[:5]
[(0, 1, 2, 3), (0, 1, 3, 2), (0, 3, 1, 2), (3, 0, 1, 2), (3, 0, 2, 1)]
Notice how the 2nd and 3rd lexicographical permutations have 3 elements
out of place whereas each "bell" permutation always has only two
elements out of place relative to the previous permutation (and so the
signature (+/-1) of a permutation is opposite of the signature of the
previous permutation).
How the position of inversion varies across the elements can be seen
by tracing out where the largest number appears in the permutations:
>>> m = zeros(4, 24)
>>> for i, p in enumerate(generate_bell(4)):
... m[:, i] = Matrix([j - 3 for j in list(p)]) # make largest zero
>>> m.print_nonzero('X')
[XXX XXXXXX XXXXXX XXX]
[XX XX XXXX XX XXXX XX XX]
[X XXXX XX XXXX XX XXXX X]
[ XXXXXX XXXXXX XXXXXX ]
See Also
========
sympy.combinatorics.permutations.Permutation.next_trotterjohnson
References
==========
.. [1] https://en.wikipedia.org/wiki/Method_ringing
.. [2] https://stackoverflow.com/questions/4856615/recursive-permutation/4857018
.. [3] http://programminggeeks.com/bell-algorithm-for-permutation/
.. [4] https://en.wikipedia.org/wiki/Steinhaus%E2%80%93Johnson%E2%80%93Trotter_algorithm
.. [5] Generating involutions, derangements, and relatives by ECO
Vincent Vajnovszki, DMTCS vol 1 issue 12, 2010
"""
n = as_int(n)
if n < 1:
raise ValueError('n must be a positive integer')
if n == 1:
yield (0,)
elif n == 2:
yield (0, 1)
yield (1, 0)
elif n == 3:
yield from [(0, 1, 2), (0, 2, 1), (2, 0, 1), (2, 1, 0), (1, 2, 0), (1, 0, 2)]
else:
m = n - 1
op = [0] + [-1]*m
l = list(range(n))
while True:
yield tuple(l)
# find biggest element with op
big = None, -1 # idx, value
for i in range(n):
if op[i] and l[i] > big[1]:
big = i, l[i]
i, _ = big
if i is None:
break # there are no ops left
# swap it with neighbor in the indicated direction
j = i + op[i]
l[i], l[j] = l[j], l[i]
op[i], op[j] = op[j], op[i]
# if it landed at the end or if the neighbor in the same
# direction is bigger then turn off op
if j == 0 or j == m or l[j + op[j]] > l[j]:
op[j] = 0
# any element bigger to the left gets +1 op
for i in range(j):
if l[i] > l[j]:
op[i] = 1
# any element bigger to the right gets -1 op
for i in range(j + 1, n):
if l[i] > l[j]:
op[i] = -1
def generate_involutions(n):
"""
Generates involutions.
An involution is a permutation that when multiplied
by itself equals the identity permutation. In this
implementation the involutions are generated using
Fixed Points.
Alternatively, an involution can be considered as
a permutation that does not contain any cycles with
a length that is greater than two.
Examples
========
>>> from sympy.utilities.iterables import generate_involutions
>>> list(generate_involutions(3))
[(0, 1, 2), (0, 2, 1), (1, 0, 2), (2, 1, 0)]
>>> len(list(generate_involutions(4)))
10
References
==========
.. [1] http://mathworld.wolfram.com/PermutationInvolution.html
"""
idx = list(range(n))
for p in permutations(idx):
for i in idx:
if p[p[i]] != i:
break
else:
yield p
def generate_derangements(perm):
"""
Routine to generate unique derangements.
TODO: This will be rewritten to use the
ECO operator approach once the permutations
branch is in master.
Examples
========
>>> from sympy.utilities.iterables import generate_derangements
>>> list(generate_derangements([0, 1, 2]))
[[1, 2, 0], [2, 0, 1]]
>>> list(generate_derangements([0, 1, 2, 3]))
[[1, 0, 3, 2], [1, 2, 3, 0], [1, 3, 0, 2], [2, 0, 3, 1], \
[2, 3, 0, 1], [2, 3, 1, 0], [3, 0, 1, 2], [3, 2, 0, 1], \
[3, 2, 1, 0]]
>>> list(generate_derangements([0, 1, 1]))
[]
See Also
========
sympy.functions.combinatorial.factorials.subfactorial
"""
for p in multiset_permutations(perm):
if not any(i == j for i, j in zip(perm, p)):
yield p
def necklaces(n, k, free=False):
"""
A routine to generate necklaces that may (free=True) or may not
(free=False) be turned over to be viewed. The "necklaces" returned
are comprised of ``n`` integers (beads) with ``k`` different
values (colors). Only unique necklaces are returned.
Examples
========
>>> from sympy.utilities.iterables import necklaces, bracelets
>>> def show(s, i):
... return ''.join(s[j] for j in i)
The "unrestricted necklace" is sometimes also referred to as a
"bracelet" (an object that can be turned over, a sequence that can
be reversed) and the term "necklace" is used to imply a sequence
that cannot be reversed. So ACB == ABC for a bracelet (rotate and
reverse) while the two are different for a necklace since rotation
alone cannot make the two sequences the same.
(mnemonic: Bracelets can be viewed Backwards, but Not Necklaces.)
>>> B = [show('ABC', i) for i in bracelets(3, 3)]
>>> N = [show('ABC', i) for i in necklaces(3, 3)]
>>> set(N) - set(B)
{'ACB'}
>>> list(necklaces(4, 2))
[(0, 0, 0, 0), (0, 0, 0, 1), (0, 0, 1, 1),
(0, 1, 0, 1), (0, 1, 1, 1), (1, 1, 1, 1)]
>>> [show('.o', i) for i in bracelets(4, 2)]
['....', '...o', '..oo', '.o.o', '.ooo', 'oooo']
References
==========
.. [1] http://mathworld.wolfram.com/Necklace.html
"""
return uniq(minlex(i, directed=not free) for i in
variations(list(range(k)), n, repetition=True))
def bracelets(n, k):
"""Wrapper to necklaces to return a free (unrestricted) necklace."""
return necklaces(n, k, free=True)
def generate_oriented_forest(n):
"""
This algorithm generates oriented forests.
An oriented graph is a directed graph having no symmetric pair of directed
edges. A forest is an acyclic graph, i.e., it has no cycles. A forest can
also be described as a disjoint union of trees, which are graphs in which
any two vertices are connected by exactly one simple path.
Examples
========
>>> from sympy.utilities.iterables import generate_oriented_forest
>>> list(generate_oriented_forest(4))
[[0, 1, 2, 3], [0, 1, 2, 2], [0, 1, 2, 1], [0, 1, 2, 0], \
[0, 1, 1, 1], [0, 1, 1, 0], [0, 1, 0, 1], [0, 1, 0, 0], [0, 0, 0, 0]]
References
==========
.. [1] T. Beyer and S.M. Hedetniemi: constant time generation of
rooted trees, SIAM J. Computing Vol. 9, No. 4, November 1980
.. [2] https://stackoverflow.com/questions/1633833/oriented-forest-taocp-algorithm-in-python
"""
P = list(range(-1, n))
while True:
yield P[1:]
if P[n] > 0:
P[n] = P[P[n]]
else:
for p in range(n - 1, 0, -1):
if P[p] != 0:
target = P[p] - 1
for q in range(p - 1, 0, -1):
if P[q] == target:
break
offset = p - q
for i in range(p, n + 1):
P[i] = P[i - offset]
break
else:
break
def minlex(seq, directed=True, key=None):
"""
Return the rotation of the sequence in which the lexically smallest
elements appear first, e.g. `cba ->acb`.
The sequence returned is a tuple, unless the input sequence is a string
in which case a string is returned.
If ``directed`` is False then the smaller of the sequence and the
reversed sequence is returned, e.g. `cba -> abc`.
If ``key`` is not None then it is used to extract a comparison key from each element in iterable.
Examples
========
>>> from sympy.combinatorics.polyhedron import minlex
>>> minlex((1, 2, 0))
(0, 1, 2)
>>> minlex((1, 0, 2))
(0, 2, 1)
>>> minlex((1, 0, 2), directed=False)
(0, 1, 2)
>>> minlex('11010011000', directed=True)
'00011010011'
>>> minlex('11010011000', directed=False)
'00011001011'
>>> minlex(('bb', 'aaa', 'c', 'a'))
('a', 'bb', 'aaa', 'c')
>>> minlex(('bb', 'aaa', 'c', 'a'), key=len)
('c', 'a', 'bb', 'aaa')
"""
if key is None: key = sympy.Id
best = rotate_left(seq, least_rotation(seq, key=key))
if not directed:
rseq = seq[::-1]
rbest = rotate_left(rseq, least_rotation(rseq, key=key))
best = min(best, rbest, key=key)
# Convert to tuple, unless we started with a string.
return tuple(best) if not isinstance(seq, str) else best
def runs(seq, op=gt):
"""Group the sequence into lists in which successive elements
all compare the same with the comparison operator, ``op``:
op(seq[i + 1], seq[i]) is True from all elements in a run.
Examples
========
>>> from sympy.utilities.iterables import runs
>>> from operator import ge
>>> runs([0, 1, 2, 2, 1, 4, 3, 2, 2])
[[0, 1, 2], [2], [1, 4], [3], [2], [2]]
>>> runs([0, 1, 2, 2, 1, 4, 3, 2, 2], op=ge)
[[0, 1, 2, 2], [1, 4], [3], [2, 2]]
"""
cycles = []
seq = iter(seq)
try:
run = [next(seq)]
except StopIteration:
return []
while True:
try:
ei = next(seq)
except StopIteration:
break
if op(ei, run[-1]):
run.append(ei)
continue
else:
cycles.append(run)
run = [ei]
if run:
cycles.append(run)
return cycles
def kbins(l, k, ordered=None):
"""
Return sequence ``l`` partitioned into ``k`` bins.
Examples
========
>>> from __future__ import print_function
The default is to give the items in the same order, but grouped
into k partitions without any reordering:
>>> from sympy.utilities.iterables import kbins
>>> for p in kbins(list(range(5)), 2):
... print(p)
...
[[0], [1, 2, 3, 4]]
[[0, 1], [2, 3, 4]]
[[0, 1, 2], [3, 4]]
[[0, 1, 2, 3], [4]]
The ``ordered`` flag is either None (to give the simple partition
of the elements) or is a 2 digit integer indicating whether the order of
the bins and the order of the items in the bins matters. Given::
A = [[0], [1, 2]]
B = [[1, 2], [0]]
C = [[2, 1], [0]]
D = [[0], [2, 1]]
the following values for ``ordered`` have the shown meanings::
00 means A == B == C == D
01 means A == B
10 means A == D
11 means A == A
>>> for ordered_flag in [None, 0, 1, 10, 11]:
... print('ordered = %s' % ordered_flag)
... for p in kbins(list(range(3)), 2, ordered=ordered_flag):
... print(' %s' % p)
...
ordered = None
[[0], [1, 2]]
[[0, 1], [2]]
ordered = 0
[[0, 1], [2]]
[[0, 2], [1]]
[[0], [1, 2]]
ordered = 1
[[0], [1, 2]]
[[0], [2, 1]]
[[1], [0, 2]]
[[1], [2, 0]]
[[2], [0, 1]]
[[2], [1, 0]]
ordered = 10
[[0, 1], [2]]
[[2], [0, 1]]
[[0, 2], [1]]
[[1], [0, 2]]
[[0], [1, 2]]
[[1, 2], [0]]
ordered = 11
[[0], [1, 2]]
[[0, 1], [2]]
[[0], [2, 1]]
[[0, 2], [1]]
[[1], [0, 2]]
[[1, 0], [2]]
[[1], [2, 0]]
[[1, 2], [0]]
[[2], [0, 1]]
[[2, 0], [1]]
[[2], [1, 0]]
[[2, 1], [0]]
See Also
========
partitions, multiset_partitions
"""
def partition(lista, bins):
# EnricoGiampieri's partition generator from
# https://stackoverflow.com/questions/13131491/
# partition-n-items-into-k-bins-in-python-lazily
if len(lista) == 1 or bins == 1:
yield [lista]
elif len(lista) > 1 and bins > 1:
for i in range(1, len(lista)):
for part in partition(lista[i:], bins - 1):
if len([lista[:i]] + part) == bins:
yield [lista[:i]] + part
if ordered is None:
yield from partition(l, k)
elif ordered == 11:
for pl in multiset_permutations(l):
pl = list(pl)
yield from partition(pl, k)
elif ordered == 00:
yield from multiset_partitions(l, k)
elif ordered == 10:
for p in multiset_partitions(l, k):
for perm in permutations(p):
yield list(perm)
elif ordered == 1:
for kgot, p in partitions(len(l), k, size=True):
if kgot != k:
continue
for li in multiset_permutations(l):
rv = []
i = j = 0
li = list(li)
for size, multiplicity in sorted(p.items()):
for m in range(multiplicity):
j = i + size
rv.append(li[i: j])
i = j
yield rv
else:
raise ValueError(
'ordered must be one of 00, 01, 10 or 11, not %s' % ordered)
def permute_signs(t):
"""Return iterator in which the signs of non-zero elements
of t are permuted.
Examples
========
>>> from sympy.utilities.iterables import permute_signs
>>> list(permute_signs((0, 1, 2)))
[(0, 1, 2), (0, -1, 2), (0, 1, -2), (0, -1, -2)]
"""
for signs in cartes(*[(1, -1)]*(len(t) - t.count(0))):
signs = list(signs)
yield type(t)([i*signs.pop() if i else i for i in t])
def signed_permutations(t):
"""Return iterator in which the signs of non-zero elements
of t and the order of the elements are permuted.
Examples
========
>>> from sympy.utilities.iterables import signed_permutations
>>> list(signed_permutations((0, 1, 2)))
[(0, 1, 2), (0, -1, 2), (0, 1, -2), (0, -1, -2), (0, 2, 1),
(0, -2, 1), (0, 2, -1), (0, -2, -1), (1, 0, 2), (-1, 0, 2),
(1, 0, -2), (-1, 0, -2), (1, 2, 0), (-1, 2, 0), (1, -2, 0),
(-1, -2, 0), (2, 0, 1), (-2, 0, 1), (2, 0, -1), (-2, 0, -1),
(2, 1, 0), (-2, 1, 0), (2, -1, 0), (-2, -1, 0)]
"""
return (type(t)(i) for j in permutations(t)
for i in permute_signs(j))
def rotations(s, dir=1):
"""Return a generator giving the items in s as list where
each subsequent list has the items rotated to the left (default)
or right (dir=-1) relative to the previous list.
Examples
========
>>> from sympy.utilities.iterables import rotations
>>> list(rotations([1,2,3]))
[[1, 2, 3], [2, 3, 1], [3, 1, 2]]
>>> list(rotations([1,2,3], -1))
[[1, 2, 3], [3, 1, 2], [2, 3, 1]]
"""
seq = list(s)
for i in range(len(seq)):
yield seq
seq = rotate_left(seq, dir)
def roundrobin(*iterables):
"""roundrobin recipe taken from itertools documentation:
https://docs.python.org/2/library/itertools.html#recipes
roundrobin('ABC', 'D', 'EF') --> A D E B F C
Recipe credited to George Sakkis
"""
import itertools
nexts = itertools.cycle(iter(it).__next__ for it in iterables)
pending = len(iterables)
while pending:
try:
for next in nexts:
yield next()
except StopIteration:
pending -= 1
nexts = itertools.cycle(itertools.islice(nexts, pending))
|
33d29128e7fb82fbf965bb95ce76eac31174302187d88d280cddccc2b589e550 | from sympy.core import S
from .pycode import PythonCodePrinter, _known_functions_math, _print_known_const, _print_known_func, _unpack_integral_limits
from .codeprinter import CodePrinter
_not_in_numpy = 'erf erfc factorial gamma loggamma'.split()
_in_numpy = [(k, v) for k, v in _known_functions_math.items() if k not in _not_in_numpy]
_known_functions_numpy = dict(_in_numpy, **{
'acos': 'arccos',
'acosh': 'arccosh',
'asin': 'arcsin',
'asinh': 'arcsinh',
'atan': 'arctan',
'atan2': 'arctan2',
'atanh': 'arctanh',
'exp2': 'exp2',
'sign': 'sign',
'logaddexp': 'logaddexp',
'logaddexp2': 'logaddexp2',
})
_known_constants_numpy = {
'Exp1': 'e',
'Pi': 'pi',
'EulerGamma': 'euler_gamma',
'NaN': 'nan',
'Infinity': 'PINF',
'NegativeInfinity': 'NINF'
}
_numpy_known_functions = {k: 'numpy.' + v for k, v in _known_functions_numpy.items()}
_numpy_known_constants = {k: 'numpy.' + v for k, v in _known_constants_numpy.items()}
class NumPyPrinter(PythonCodePrinter):
"""
Numpy printer which handles vectorized piecewise functions,
logical operators, etc.
"""
_module = 'numpy'
_kf = _numpy_known_functions
_kc = _numpy_known_constants
def __init__(self, settings=None):
"""
`settings` is passed to CodePrinter.__init__()
`module` specifies the array module to use, currently 'NumPy' or 'CuPy'
"""
self.language = "Python with {}".format(self._module)
self.printmethod = "_{}code".format(self._module)
self._kf = {**PythonCodePrinter._kf, **self._kf}
super().__init__(settings=settings)
def _print_seq(self, seq):
"General sequence printer: converts to tuple"
# Print tuples here instead of lists because numba supports
# tuples in nopython mode.
delimiter=', '
return '({},)'.format(delimiter.join(self._print(item) for item in seq))
def _print_MatMul(self, expr):
"Matrix multiplication printer"
if expr.as_coeff_matrices()[0] is not S.One:
expr_list = expr.as_coeff_matrices()[1]+[(expr.as_coeff_matrices()[0])]
return '({})'.format(').dot('.join(self._print(i) for i in expr_list))
return '({})'.format(').dot('.join(self._print(i) for i in expr.args))
def _print_MatPow(self, expr):
"Matrix power printer"
return '{}({}, {})'.format(self._module_format(self._module + '.linalg.matrix_power'),
self._print(expr.args[0]), self._print(expr.args[1]))
def _print_Inverse(self, expr):
"Matrix inverse printer"
return '{}({})'.format(self._module_format(self._module + '.linalg.inv'),
self._print(expr.args[0]))
def _print_DotProduct(self, expr):
# DotProduct allows any shape order, but numpy.dot does matrix
# multiplication, so we have to make sure it gets 1 x n by n x 1.
arg1, arg2 = expr.args
if arg1.shape[0] != 1:
arg1 = arg1.T
if arg2.shape[1] != 1:
arg2 = arg2.T
return "%s(%s, %s)" % (self._module_format(self._module + '.dot'),
self._print(arg1),
self._print(arg2))
def _print_MatrixSolve(self, expr):
return "%s(%s, %s)" % (self._module_format(self._module + '.linalg.solve'),
self._print(expr.matrix),
self._print(expr.vector))
def _print_ZeroMatrix(self, expr):
return '{}({})'.format(self._module_format(self._module + '.zeros'),
self._print(expr.shape))
def _print_OneMatrix(self, expr):
return '{}({})'.format(self._module_format(self._module + '.ones'),
self._print(expr.shape))
def _print_FunctionMatrix(self, expr):
from sympy.core.function import Lambda
from sympy.abc import i, j
lamda = expr.lamda
if not isinstance(lamda, Lambda):
lamda = Lambda((i, j), lamda(i, j))
return '{}(lambda {}: {}, {})'.format(self._module_format(self._module + '.fromfunction'),
', '.join(self._print(arg) for arg in lamda.args[0]),
self._print(lamda.args[1]), self._print(expr.shape))
def _print_HadamardProduct(self, expr):
func = self._module_format(self._module + '.multiply')
return ''.join('{}({}, '.format(func, self._print(arg)) \
for arg in expr.args[:-1]) + "{}{}".format(self._print(expr.args[-1]),
')' * (len(expr.args) - 1))
def _print_KroneckerProduct(self, expr):
func = self._module_format(self._module + '.kron')
return ''.join('{}({}, '.format(func, self._print(arg)) \
for arg in expr.args[:-1]) + "{}{}".format(self._print(expr.args[-1]),
')' * (len(expr.args) - 1))
def _print_Adjoint(self, expr):
return '{}({}({}))'.format(
self._module_format(self._module + '.conjugate'),
self._module_format(self._module + '.transpose'),
self._print(expr.args[0]))
def _print_DiagonalOf(self, expr):
vect = '{}({})'.format(
self._module_format(self._module + '.diag'),
self._print(expr.arg))
return '{}({}, (-1, 1))'.format(
self._module_format(self._module + '.reshape'), vect)
def _print_DiagMatrix(self, expr):
return '{}({})'.format(self._module_format(self._module + '.diagflat'),
self._print(expr.args[0]))
def _print_DiagonalMatrix(self, expr):
return '{}({}, {}({}, {}))'.format(self._module_format(self._module + '.multiply'),
self._print(expr.arg), self._module_format(self._module + '.eye'),
self._print(expr.shape[0]), self._print(expr.shape[1]))
def _print_Piecewise(self, expr):
"Piecewise function printer"
exprs = '[{}]'.format(','.join(self._print(arg.expr) for arg in expr.args))
conds = '[{}]'.format(','.join(self._print(arg.cond) for arg in expr.args))
# If [default_value, True] is a (expr, cond) sequence in a Piecewise object
# it will behave the same as passing the 'default' kwarg to select()
# *as long as* it is the last element in expr.args.
# If this is not the case, it may be triggered prematurely.
return '{}({}, {}, default={})'.format(
self._module_format(self._module + '.select'), conds, exprs,
self._print(S.NaN))
def _print_Relational(self, expr):
"Relational printer for Equality and Unequality"
op = {
'==' :'equal',
'!=' :'not_equal',
'<' :'less',
'<=' :'less_equal',
'>' :'greater',
'>=' :'greater_equal',
}
if expr.rel_op in op:
lhs = self._print(expr.lhs)
rhs = self._print(expr.rhs)
return '{op}({lhs}, {rhs})'.format(op=self._module_format(self._module + '.'+op[expr.rel_op]),
lhs=lhs, rhs=rhs)
return super()._print_Relational(expr)
def _print_And(self, expr):
"Logical And printer"
# We have to override LambdaPrinter because it uses Python 'and' keyword.
# If LambdaPrinter didn't define it, we could use StrPrinter's
# version of the function and add 'logical_and' to NUMPY_TRANSLATIONS.
return '{}.reduce(({}))'.format(self._module_format(self._module + '.logical_and'), ','.join(self._print(i) for i in expr.args))
def _print_Or(self, expr):
"Logical Or printer"
# We have to override LambdaPrinter because it uses Python 'or' keyword.
# If LambdaPrinter didn't define it, we could use StrPrinter's
# version of the function and add 'logical_or' to NUMPY_TRANSLATIONS.
return '{}.reduce(({}))'.format(self._module_format(self._module + '.logical_or'), ','.join(self._print(i) for i in expr.args))
def _print_Not(self, expr):
"Logical Not printer"
# We have to override LambdaPrinter because it uses Python 'not' keyword.
# If LambdaPrinter didn't define it, we would still have to define our
# own because StrPrinter doesn't define it.
return '{}({})'.format(self._module_format(self._module + '.logical_not'), ','.join(self._print(i) for i in expr.args))
def _print_Pow(self, expr, rational=False):
# XXX Workaround for negative integer power error
from sympy.core.power import Pow
if expr.exp.is_integer and expr.exp.is_negative:
expr = Pow(expr.base, expr.exp.evalf(), evaluate=False)
return self._hprint_Pow(expr, rational=rational, sqrt=self._module + '.sqrt')
def _print_Min(self, expr):
return '{}(({}), axis=0)'.format(self._module_format(self._module + '.amin'), ','.join(self._print(i) for i in expr.args))
def _print_Max(self, expr):
return '{}(({}), axis=0)'.format(self._module_format(self._module + '.amax'), ','.join(self._print(i) for i in expr.args))
def _print_arg(self, expr):
return "%s(%s)" % (self._module_format(self._module + '.angle'), self._print(expr.args[0]))
def _print_im(self, expr):
return "%s(%s)" % (self._module_format(self._module + '.imag'), self._print(expr.args[0]))
def _print_Mod(self, expr):
return "%s(%s)" % (self._module_format(self._module + '.mod'), ', '.join(
map(lambda arg: self._print(arg), expr.args)))
def _print_re(self, expr):
return "%s(%s)" % (self._module_format(self._module + '.real'), self._print(expr.args[0]))
def _print_sinc(self, expr):
return "%s(%s)" % (self._module_format(self._module + '.sinc'), self._print(expr.args[0]/S.Pi))
def _print_MatrixBase(self, expr):
func = self.known_functions.get(expr.__class__.__name__, None)
if func is None:
func = self._module_format(self._module + '.array')
return "%s(%s)" % (func, self._print(expr.tolist()))
def _print_Identity(self, expr):
shape = expr.shape
if all([dim.is_Integer for dim in shape]):
return "%s(%s)" % (self._module_format(self._module + '.eye'), self._print(expr.shape[0]))
else:
raise NotImplementedError("Symbolic matrix dimensions are not yet supported for identity matrices")
def _print_BlockMatrix(self, expr):
return '{}({})'.format(self._module_format(self._module + '.block'),
self._print(expr.args[0].tolist()))
def _print_ArrayTensorProduct(self, expr):
array_list = [j for i, arg in enumerate(expr.args) for j in
(self._print(arg), "[%i, %i]" % (2*i, 2*i+1))]
return "%s(%s)" % (self._module_format(self._module + '.einsum'), ", ".join(array_list))
def _print_ArrayContraction(self, expr):
from ..tensor.array.expressions.array_expressions import ArrayTensorProduct
base = expr.expr
contraction_indices = expr.contraction_indices
if not contraction_indices:
return self._print(base)
if isinstance(base, ArrayTensorProduct):
counter = 0
d = {j: min(i) for i in contraction_indices for j in i}
indices = []
for rank_arg in base.subranks:
lindices = []
for i in range(rank_arg):
if counter in d:
lindices.append(d[counter])
else:
lindices.append(counter)
counter += 1
indices.append(lindices)
elems = ["%s, %s" % (self._print(arg), ind) for arg, ind in zip(base.args, indices)]
return "%s(%s)" % (
self._module_format(self._module + '.einsum'),
", ".join(elems)
)
raise NotImplementedError()
def _print_ArrayDiagonal(self, expr):
diagonal_indices = list(expr.diagonal_indices)
if len(diagonal_indices) > 1:
# TODO: this should be handled in sympy.codegen.array_utils,
# possibly by creating the possibility of unfolding the
# ArrayDiagonal object into nested ones. Same reasoning for
# the array contraction.
raise NotImplementedError
if len(diagonal_indices[0]) != 2:
raise NotImplementedError
return "%s(%s, 0, axis1=%s, axis2=%s)" % (
self._module_format("numpy.diagonal"),
self._print(expr.expr),
diagonal_indices[0][0],
diagonal_indices[0][1],
)
def _print_PermuteDims(self, expr):
return "%s(%s, %s)" % (
self._module_format("numpy.transpose"),
self._print(expr.expr),
self._print(expr.permutation.array_form),
)
def _print_ArrayAdd(self, expr):
return self._expand_fold_binary_op(self._module + '.add', expr.args)
_print_lowergamma = CodePrinter._print_not_supported
_print_uppergamma = CodePrinter._print_not_supported
_print_fresnelc = CodePrinter._print_not_supported
_print_fresnels = CodePrinter._print_not_supported
for func in _numpy_known_functions:
setattr(NumPyPrinter, f'_print_{func}', _print_known_func)
for const in _numpy_known_constants:
setattr(NumPyPrinter, f'_print_{const}', _print_known_const)
_known_functions_scipy_special = {
'erf': 'erf',
'erfc': 'erfc',
'besselj': 'jv',
'bessely': 'yv',
'besseli': 'iv',
'besselk': 'kv',
'cosm1': 'cosm1',
'factorial': 'factorial',
'gamma': 'gamma',
'loggamma': 'gammaln',
'digamma': 'psi',
'RisingFactorial': 'poch',
'jacobi': 'eval_jacobi',
'gegenbauer': 'eval_gegenbauer',
'chebyshevt': 'eval_chebyt',
'chebyshevu': 'eval_chebyu',
'legendre': 'eval_legendre',
'hermite': 'eval_hermite',
'laguerre': 'eval_laguerre',
'assoc_laguerre': 'eval_genlaguerre',
'beta': 'beta',
'LambertW' : 'lambertw',
}
_known_constants_scipy_constants = {
'GoldenRatio': 'golden_ratio',
'Pi': 'pi',
}
_scipy_known_functions = {k : "scipy.special." + v for k, v in _known_functions_scipy_special.items()}
_scipy_known_constants = {k : "scipy.constants." + v for k, v in _known_constants_scipy_constants.items()}
class SciPyPrinter(NumPyPrinter):
_kf = {**NumPyPrinter._kf, **_scipy_known_functions}
_kc = {**NumPyPrinter._kc, **_scipy_known_constants}
def __init__(self, settings=None):
super().__init__(settings=settings)
self.language = "Python with SciPy and NumPy"
def _print_SparseMatrix(self, expr):
i, j, data = [], [], []
for (r, c), v in expr.todok().items():
i.append(r)
j.append(c)
data.append(v)
return "{name}(({data}, ({i}, {j})), shape={shape})".format(
name=self._module_format('scipy.sparse.coo_matrix'),
data=data, i=i, j=j, shape=expr.shape
)
_print_ImmutableSparseMatrix = _print_SparseMatrix
# SciPy's lpmv has a different order of arguments from assoc_legendre
def _print_assoc_legendre(self, expr):
return "{0}({2}, {1}, {3})".format(
self._module_format('scipy.special.lpmv'),
self._print(expr.args[0]),
self._print(expr.args[1]),
self._print(expr.args[2]))
def _print_lowergamma(self, expr):
return "{0}({2})*{1}({2}, {3})".format(
self._module_format('scipy.special.gamma'),
self._module_format('scipy.special.gammainc'),
self._print(expr.args[0]),
self._print(expr.args[1]))
def _print_uppergamma(self, expr):
return "{0}({2})*{1}({2}, {3})".format(
self._module_format('scipy.special.gamma'),
self._module_format('scipy.special.gammaincc'),
self._print(expr.args[0]),
self._print(expr.args[1]))
def _print_betainc(self, expr):
betainc = self._module_format('scipy.special.betainc')
beta = self._module_format('scipy.special.beta')
args = [self._print(arg) for arg in expr.args]
return f"({betainc}({args[0]}, {args[1]}, {args[3]}) - {betainc}({args[0]}, {args[1]}, {args[2]})) \
* {beta}({args[0]}, {args[1]})"
def _print_betainc_regularized(self, expr):
return "{0}({1}, {2}, {4}) - {0}({1}, {2}, {3})".format(
self._module_format('scipy.special.betainc'),
self._print(expr.args[0]),
self._print(expr.args[1]),
self._print(expr.args[2]),
self._print(expr.args[3]))
def _print_fresnels(self, expr):
return "{}({})[0]".format(
self._module_format("scipy.special.fresnel"),
self._print(expr.args[0]))
def _print_fresnelc(self, expr):
return "{}({})[1]".format(
self._module_format("scipy.special.fresnel"),
self._print(expr.args[0]))
def _print_airyai(self, expr):
return "{}({})[0]".format(
self._module_format("scipy.special.airy"),
self._print(expr.args[0]))
def _print_airyaiprime(self, expr):
return "{}({})[1]".format(
self._module_format("scipy.special.airy"),
self._print(expr.args[0]))
def _print_airybi(self, expr):
return "{}({})[2]".format(
self._module_format("scipy.special.airy"),
self._print(expr.args[0]))
def _print_airybiprime(self, expr):
return "{}({})[3]".format(
self._module_format("scipy.special.airy"),
self._print(expr.args[0]))
def _print_Integral(self, e):
integration_vars, limits = _unpack_integral_limits(e)
if len(limits) == 1:
# nicer (but not necessary) to prefer quad over nquad for 1D case
module_str = self._module_format("scipy.integrate.quad")
limit_str = "%s, %s" % tuple(map(self._print, limits[0]))
else:
module_str = self._module_format("scipy.integrate.nquad")
limit_str = "({})".format(", ".join(
"(%s, %s)" % tuple(map(self._print, l)) for l in limits))
return "{}(lambda {}: {}, {})[0]".format(
module_str,
", ".join(map(self._print, integration_vars)),
self._print(e.args[0]),
limit_str)
for func in _scipy_known_functions:
setattr(SciPyPrinter, f'_print_{func}', _print_known_func)
for const in _scipy_known_constants:
setattr(SciPyPrinter, f'_print_{const}', _print_known_const)
_cupy_known_functions = {k : "cupy." + v for k, v in _known_functions_numpy.items()}
_cupy_known_constants = {k : "cupy." + v for k, v in _known_constants_numpy.items()}
class CuPyPrinter(NumPyPrinter):
"""
CuPy printer which handles vectorized piecewise functions,
logical operators, etc.
"""
_module = 'cupy'
_kf = _cupy_known_functions
_kc = _cupy_known_constants
def __init__(self, settings=None):
super().__init__(settings=settings)
for func in _cupy_known_functions:
setattr(CuPyPrinter, f'_print_{func}', _print_known_func)
for const in _cupy_known_constants:
setattr(CuPyPrinter, f'_print_{const}', _print_known_const)
|
9ab150687bf70242e695c256dd8b60cf12b619d7257ce00872eac84f7b2fabd3 | """
A Printer for generating readable representation of most sympy classes.
"""
from typing import Any, Dict
from sympy.core import S, Rational, Pow, Basic, Mul, Number
from sympy.core.mul import _keep_coeff
from sympy.core.function import _coeff_isneg
from .printer import Printer, print_function
from sympy.printing.precedence import precedence, PRECEDENCE
from mpmath.libmp import prec_to_dps, to_str as mlib_to_str
from sympy.utilities import default_sort_key, sift
class StrPrinter(Printer):
printmethod = "_sympystr"
_default_settings = {
"order": None,
"full_prec": "auto",
"sympy_integers": False,
"abbrev": False,
"perm_cyclic": True,
"min": None,
"max": None,
} # type: Dict[str, Any]
_relationals = dict() # type: Dict[str, str]
def parenthesize(self, item, level, strict=False):
if (precedence(item) < level) or ((not strict) and precedence(item) <= level):
return "(%s)" % self._print(item)
else:
return self._print(item)
def stringify(self, args, sep, level=0):
return sep.join([self.parenthesize(item, level) for item in args])
def emptyPrinter(self, expr):
if isinstance(expr, str):
return expr
elif isinstance(expr, Basic):
return repr(expr)
else:
return str(expr)
def _print_Add(self, expr, order=None):
terms = self._as_ordered_terms(expr, order=order)
PREC = precedence(expr)
l = []
for term in terms:
t = self._print(term)
if t.startswith('-'):
sign = "-"
t = t[1:]
else:
sign = "+"
if precedence(term) < PREC:
l.extend([sign, "(%s)" % t])
else:
l.extend([sign, t])
sign = l.pop(0)
if sign == '+':
sign = ""
return sign + ' '.join(l)
def _print_BooleanTrue(self, expr):
return "True"
def _print_BooleanFalse(self, expr):
return "False"
def _print_Not(self, expr):
return '~%s' %(self.parenthesize(expr.args[0],PRECEDENCE["Not"]))
def _print_And(self, expr):
return self.stringify(expr.args, " & ", PRECEDENCE["BitwiseAnd"])
def _print_Or(self, expr):
return self.stringify(expr.args, " | ", PRECEDENCE["BitwiseOr"])
def _print_Xor(self, expr):
return self.stringify(expr.args, " ^ ", PRECEDENCE["BitwiseXor"])
def _print_AppliedPredicate(self, expr):
return '%s(%s)' % (
self._print(expr.function), self.stringify(expr.arguments, ", "))
def _print_Basic(self, expr):
l = [self._print(o) for o in expr.args]
return expr.__class__.__name__ + "(%s)" % ", ".join(l)
def _print_BlockMatrix(self, B):
if B.blocks.shape == (1, 1):
self._print(B.blocks[0, 0])
return self._print(B.blocks)
def _print_Catalan(self, expr):
return 'Catalan'
def _print_ComplexInfinity(self, expr):
return 'zoo'
def _print_ConditionSet(self, s):
args = tuple([self._print(i) for i in (s.sym, s.condition)])
if s.base_set is S.UniversalSet:
return 'ConditionSet(%s, %s)' % args
args += (self._print(s.base_set),)
return 'ConditionSet(%s, %s, %s)' % 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 'Derivative(%s)' % ", ".join(map(lambda arg: self._print(arg), [dexpr] + dvars))
def _print_dict(self, d):
keys = sorted(d.keys(), key=default_sort_key)
items = []
for key in keys:
item = "%s: %s" % (self._print(key), self._print(d[key]))
items.append(item)
return "{%s}" % ", ".join(items)
def _print_Dict(self, expr):
return self._print_dict(expr)
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))
else:
return 'Domain on ' + self._print(d.symbols)
def _print_Dummy(self, expr):
return '_' + expr.name
def _print_EulerGamma(self, expr):
return 'EulerGamma'
def _print_Exp1(self, expr):
return 'E'
def _print_ExprCondPair(self, expr):
return '(%s, %s)' % (self._print(expr.expr), self._print(expr.cond))
def _print_Function(self, expr):
return expr.func.__name__ + "(%s)" % self.stringify(expr.args, ", ")
def _print_GoldenRatio(self, expr):
return 'GoldenRatio'
def _print_TribonacciConstant(self, expr):
return 'TribonacciConstant'
def _print_ImaginaryUnit(self, expr):
return 'I'
def _print_Infinity(self, expr):
return 'oo'
def _print_Integral(self, expr):
def _xab_tostr(xab):
if len(xab) == 1:
return self._print(xab[0])
else:
return self._print((xab[0],) + tuple(xab[1:]))
L = ', '.join([_xab_tostr(l) for l in expr.limits])
return 'Integral(%s, %s)' % (self._print(expr.function), L)
def _print_Interval(self, i):
fin = 'Interval{m}({a}, {b})'
a, b, l, r = i.args
if a.is_infinite and b.is_infinite:
m = ''
elif a.is_infinite and not r:
m = ''
elif b.is_infinite and not l:
m = ''
elif not l and not r:
m = ''
elif l and r:
m = '.open'
elif l:
m = '.Lopen'
else:
m = '.Ropen'
return fin.format(**{'a': a, 'b': b, 'm': m})
def _print_AccumulationBounds(self, i):
return "AccumBounds(%s, %s)" % (self._print(i.min),
self._print(i.max))
def _print_Inverse(self, I):
return "%s**(-1)" % self.parenthesize(I.arg, PRECEDENCE["Pow"])
def _print_Lambda(self, obj):
expr = obj.expr
sig = obj.signature
if len(sig) == 1 and sig[0].is_symbol:
sig = sig[0]
return "Lambda(%s, %s)" % (self._print(sig), self._print(expr))
def _print_LatticeOp(self, expr):
args = sorted(expr.args, key=default_sort_key)
return expr.func.__name__ + "(%s)" % ", ".join(self._print(arg) for arg in args)
def _print_Limit(self, expr):
e, z, z0, dir = expr.args
if str(dir) == "+":
return "Limit(%s, %s, %s)" % tuple(map(self._print, (e, z, z0)))
else:
return "Limit(%s, %s, %s, dir='%s')" % tuple(map(self._print,
(e, z, z0, dir)))
def _print_list(self, expr):
return "[%s]" % self.stringify(expr, ", ")
def _print_MatrixBase(self, expr):
return expr._format_str(self)
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 strslice(x, dim):
x = list(x)
if x[2] == 1:
del x[2]
if x[0] == 0:
x[0] = ''
if x[1] == dim:
x[1] = ''
return ':'.join(map(lambda arg: self._print(arg), x))
return (self.parenthesize(expr.parent, PRECEDENCE["Atom"], strict=True) + '[' +
strslice(expr.rowslice, expr.parent.rows) + ', ' +
strslice(expr.colslice, expr.parent.cols) + ']')
def _print_DeferredVector(self, expr):
return expr.name
def _print_Mul(self, expr):
prec = precedence(expr)
# Check for unevaluated Mul. In this case we need to make sure the
# identities are visible, multiple Rational factors are not combined
# etc so we display in a straight-forward form that fully preserves all
# args and their order.
args = expr.args
if args[0] is S.One or any(
isinstance(a, Number) or
a.is_Pow and all(ai.is_Integer for ai in a.args)
for a in args[1:]):
d, n = sift(args, lambda x:
isinstance(x, Pow) and bool(x.exp.as_coeff_Mul()[0] < 0),
binary=True)
for i, di in enumerate(d):
if di.exp.is_Number:
e = -di.exp
else:
dargs = list(di.exp.args)
dargs[0] = -dargs[0]
e = Mul._from_args(dargs)
d[i] = Pow(di.base, e, evaluate=False) if e - 1 else di.base
# don't parenthesize first factor if negative
if _coeff_isneg(n[0]):
pre = [str(n.pop(0))]
else:
pre = []
nfactors = pre + [self.parenthesize(a, prec, strict=False)
for a in n]
# don't parenthesize first of denominator unless singleton
if len(d) > 1 and _coeff_isneg(d[0]):
pre = [str(d.pop(0))]
else:
pre = []
dfactors = pre + [self.parenthesize(a, prec, strict=False)
for a in d]
n = '*'.join(nfactors)
d = '*'.join(dfactors)
if len(dfactors) > 1:
return '%s/(%s)' % (n, d)
elif dfactors:
return '%s/%s' % (n, d)
return n
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
def apow(i):
b, e = i.as_base_exp()
eargs = list(Mul.make_args(e))
if eargs[0] is S.NegativeOne:
eargs = eargs[1:]
else:
eargs[0] = -eargs[0]
e = Mul._from_args(eargs)
if isinstance(i, Pow):
return i.func(b, e, evaluate=False)
return i.func(e, evaluate=False)
for item in args:
if (item.is_commutative and
isinstance(item, Pow) and
bool(item.exp.as_coeff_Mul()[0] < 0)):
if item.exp is not S.NegativeOne:
b.append(apow(item))
else:
if (len(item.args[0].args) != 1 and
isinstance(item.base, (Mul, Pow))):
# To avoid situations like #14160
pow_paren.append(item)
b.append(item.base)
elif item.is_Rational and item is not S.Infinity:
if item.p != 1:
a.append(Rational(item.p))
if item.q != 1:
b.append(Rational(item.q))
else:
a.append(item)
a = a or [S.One]
a_str = [self.parenthesize(x, prec, strict=False) for x in a]
b_str = [self.parenthesize(x, prec, strict=False) 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 not b:
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_MatMul(self, expr):
c, m = expr.as_coeff_mmul()
sign = ""
if c.is_number:
re, im = c.as_real_imag()
if im.is_zero and re.is_negative:
expr = _keep_coeff(-c, m)
sign = "-"
elif re.is_zero and im.is_negative:
expr = _keep_coeff(-c, m)
sign = "-"
return sign + '*'.join(
[self.parenthesize(arg, precedence(expr)) for arg in expr.args]
)
def _print_ElementwiseApplyFunction(self, expr):
return "{}.({})".format(
expr.function,
self._print(expr.expr),
)
def _print_NaN(self, expr):
return 'nan'
def _print_NegativeInfinity(self, expr):
return '-oo'
def _print_Order(self, expr):
if not expr.variables or all(p is S.Zero for p in expr.point):
if len(expr.variables) <= 1:
return 'O(%s)' % self._print(expr.expr)
else:
return 'O(%s)' % self.stringify((expr.expr,) + expr.variables, ', ', 0)
else:
return 'O(%s)' % self.stringify(expr.args, ', ', 0)
def _print_Ordinal(self, expr):
return expr.__str__()
def _print_Cycle(self, expr):
return expr.__str__()
def _print_Permutation(self, expr):
from sympy.combinatorics.permutations import Permutation, Cycle
from sympy.utilities.exceptions import SymPyDeprecationWarning
perm_cyclic = Permutation.print_cyclic
if perm_cyclic is not None:
SymPyDeprecationWarning(
feature="Permutation.print_cyclic = {}".format(perm_cyclic),
useinstead="init_printing(perm_cyclic={})"
.format(perm_cyclic),
issue=15201,
deprecated_since_version="1.6").warn()
else:
perm_cyclic = self._settings.get("perm_cyclic", True)
if perm_cyclic:
if not expr.size:
return '()'
# before taking Cycle notation, see if the last element is
# a singleton and move it to the head of the string
s = Cycle(expr)(expr.size - 1).__repr__()[len('Cycle'):]
last = s.rfind('(')
if not last == 0 and ',' not in s[last:]:
s = s[last:] + s[:last]
s = s.replace(',', '')
return s
else:
s = expr.support()
if not s:
if expr.size < 5:
return 'Permutation(%s)' % self._print(expr.array_form)
return 'Permutation([], size=%s)' % self._print(expr.size)
trim = self._print(expr.array_form[:s[-1] + 1]) + ', size=%s' % self._print(expr.size)
use = full = self._print(expr.array_form)
if len(trim) < len(full):
use = trim
return 'Permutation(%s)' % use
def _print_Subs(self, obj):
expr, old, new = obj.args
if len(obj.point) == 1:
old = old[0]
new = new[0]
return "Subs(%s, %s, %s)" % (
self._print(expr), self._print(old), self._print(new))
def _print_TensorIndex(self, expr):
return expr._print()
def _print_TensorHead(self, expr):
return expr._print()
def _print_Tensor(self, expr):
return expr._print()
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):
return expr._print()
def _print_ArraySymbol(self, expr):
return self._print(expr.name)
def _print_ArrayElement(self, expr):
return "%s[%s]" % (expr.name, ", ".join([self._print(i) for i in expr.indices]))
def _print_PermutationGroup(self, expr):
p = [' %s' % self._print(a) for a in expr.args]
return 'PermutationGroup([\n%s])' % ',\n'.join(p)
def _print_Pi(self, expr):
return 'pi'
def _print_PolyRing(self, ring):
return "Polynomial ring in %s over %s with %s order" % \
(", ".join(map(lambda rs: self._print(rs), ring.symbols)),
self._print(ring.domain), self._print(ring.order))
def _print_FracField(self, field):
return "Rational function field in %s over %s with %s order" % \
(", ".join(map(lambda fs: self._print(fs), field.symbols)),
self._print(field.domain), self._print(field.order))
def _print_FreeGroupElement(self, elm):
return elm.__str__()
def _print_GaussianElement(self, poly):
return "(%s + %s*I)" % (poly.x, poly.y)
def _print_PolyElement(self, poly):
return poly.str(self, PRECEDENCE, "%s**%s", "*")
def _print_FracElement(self, frac):
if frac.denom == 1:
return self._print(frac.numer)
else:
numer = self.parenthesize(frac.numer, PRECEDENCE["Mul"], strict=True)
denom = self.parenthesize(frac.denom, PRECEDENCE["Atom"], strict=True)
return numer + "/" + denom
def _print_Poly(self, expr):
ATOM_PREC = PRECEDENCE["Atom"] - 1
terms, gens = [], [ self.parenthesize(s, ATOM_PREC) for s in expr.gens ]
for monom, coeff in expr.terms():
s_monom = []
for i, e in enumerate(monom):
if e > 0:
if e == 1:
s_monom.append(gens[i])
else:
s_monom.append(gens[i] + "**%d" % e)
s_monom = "*".join(s_monom)
if coeff.is_Add:
if s_monom:
s_coeff = "(" + 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]
format = expr.__class__.__name__ + "(%s, %s"
from sympy.polys.polyerrors import PolynomialError
try:
format += ", modulus=%s" % expr.get_modulus()
except PolynomialError:
format += ", domain='%s'" % expr.get_domain()
format += ")"
for index, item in enumerate(gens):
if len(item) > 2 and (item[:1] == "(" and item[len(item) - 1:] == ")"):
gens[index] = item[1:len(item) - 1]
return format % (' '.join(terms), ', '.join(gens))
def _print_UniversalSet(self, p):
return 'UniversalSet'
def _print_AlgebraicNumber(self, expr):
if expr.is_aliased:
return self._print(expr.as_poly().as_expr())
else:
return self._print(expr.as_expr())
def _print_Pow(self, expr, rational=False):
"""Printing helper function for ``Pow``
Parameters
==========
rational : bool, optional
If ``True``, it will not attempt printing ``sqrt(x)`` or
``x**S.Half`` as ``sqrt``, and will use ``x**(1/2)``
instead.
See examples for additional details
Examples
========
>>> from sympy.functions import sqrt
>>> from sympy.printing.str import StrPrinter
>>> from sympy.abc import x
How ``rational`` keyword works with ``sqrt``:
>>> printer = StrPrinter()
>>> printer._print_Pow(sqrt(x), rational=True)
'x**(1/2)'
>>> printer._print_Pow(sqrt(x), rational=False)
'sqrt(x)'
>>> printer._print_Pow(1/sqrt(x), rational=True)
'x**(-1/2)'
>>> printer._print_Pow(1/sqrt(x), rational=False)
'1/sqrt(x)'
Notes
=====
``sqrt(x)`` is canonicalized as ``Pow(x, S.Half)`` in SymPy,
so there is no need of defining a separate printer for ``sqrt``.
Instead, it should be handled here as well.
"""
PREC = precedence(expr)
if expr.exp is S.Half and not rational:
return "sqrt(%s)" % self._print(expr.base)
if expr.is_commutative:
if -expr.exp is S.Half and not rational:
# Note: Don't test "expr.exp == -S.Half" here, because that will
# match -0.5, which we don't want.
return "%s/sqrt(%s)" % tuple(map(lambda arg: self._print(arg), (S.One, expr.base)))
if expr.exp is -S.One:
# Similarly to the S.Half case, don't test with "==" here.
return '%s/%s' % (self._print(S.One),
self.parenthesize(expr.base, PREC, strict=False))
e = self.parenthesize(expr.exp, PREC, strict=False)
if self.printmethod == '_sympyrepr' and expr.exp.is_Rational and expr.exp.q != 1:
# the parenthesized exp should be '(Rational(a, b))' so strip parens,
# but just check to be sure.
if e.startswith('(Rational'):
return '%s**%s' % (self.parenthesize(expr.base, PREC, strict=False), e[1:-1])
return '%s**%s' % (self.parenthesize(expr.base, PREC, strict=False), e)
def _print_UnevaluatedExpr(self, expr):
return self._print(expr.args[0])
def _print_MatPow(self, expr):
PREC = precedence(expr)
return '%s**%s' % (self.parenthesize(expr.base, PREC, strict=False),
self.parenthesize(expr.exp, PREC, strict=False))
def _print_Integer(self, expr):
if self._settings.get("sympy_integers", False):
return "S(%s)" % (expr)
return str(expr.p)
def _print_Integers(self, expr):
return 'Integers'
def _print_Naturals(self, expr):
return 'Naturals'
def _print_Naturals0(self, expr):
return 'Naturals0'
def _print_Rationals(self, expr):
return 'Rationals'
def _print_Reals(self, expr):
return 'Reals'
def _print_Complexes(self, expr):
return 'Complexes'
def _print_EmptySet(self, expr):
return 'EmptySet'
def _print_EmptySequence(self, expr):
return 'EmptySequence'
def _print_int(self, expr):
return str(expr)
def _print_mpz(self, expr):
return str(expr)
def _print_Rational(self, expr):
if expr.q == 1:
return str(expr.p)
else:
if self._settings.get("sympy_integers", False):
return "S(%s)/%s" % (expr.p, expr.q)
return "%s/%s" % (expr.p, expr.q)
def _print_PythonRational(self, expr):
if expr.q == 1:
return str(expr.p)
else:
return "%d/%d" % (expr.p, expr.q)
def _print_Fraction(self, expr):
if expr.denominator == 1:
return str(expr.numerator)
else:
return "%s/%s" % (expr.numerator, expr.denominator)
def _print_mpq(self, expr):
if expr.denominator == 1:
return str(expr.numerator)
else:
return "%s/%s" % (expr.numerator, expr.denominator)
def _print_Float(self, expr):
prec = expr._prec
if prec < 5:
dps = 0
else:
dps = prec_to_dps(expr._prec)
if self._settings["full_prec"] is True:
strip = False
elif self._settings["full_prec"] is False:
strip = True
elif self._settings["full_prec"] == "auto":
strip = self._print_level > 1
low = self._settings["min"] if "min" in self._settings else None
high = self._settings["max"] if "max" in self._settings else None
rv = mlib_to_str(expr._mpf_, dps, strip_zeros=strip, min_fixed=low, max_fixed=high)
if rv.startswith('-.0'):
rv = '-0.' + rv[3:]
elif rv.startswith('.0'):
rv = '0.' + rv[2:]
if rv.startswith('+'):
# e.g., +inf -> inf
rv = rv[1:]
return rv
def _print_Relational(self, expr):
charmap = {
"==": "Eq",
"!=": "Ne",
":=": "Assignment",
'+=': "AddAugmentedAssignment",
"-=": "SubAugmentedAssignment",
"*=": "MulAugmentedAssignment",
"/=": "DivAugmentedAssignment",
"%=": "ModAugmentedAssignment",
}
if expr.rel_op in charmap:
return '%s(%s, %s)' % (charmap[expr.rel_op], self._print(expr.lhs),
self._print(expr.rhs))
return '%s %s %s' % (self.parenthesize(expr.lhs, precedence(expr)),
self._relationals.get(expr.rel_op) or expr.rel_op,
self.parenthesize(expr.rhs, precedence(expr)))
def _print_ComplexRootOf(self, expr):
return "CRootOf(%s, %d)" % (self._print_Add(expr.expr, order='lex'),
expr.index)
def _print_RootSum(self, expr):
args = [self._print_Add(expr.expr, order='lex')]
if expr.fun is not S.IdentityFunction:
args.append(self._print(expr.fun))
return "RootSum(%s)" % ", ".join(args)
def _print_GroebnerBasis(self, basis):
cls = basis.__class__.__name__
exprs = [self._print_Add(arg, order=basis.order) for arg in basis.exprs]
exprs = "[%s]" % ", ".join(exprs)
gens = [ self._print(gen) for gen in basis.gens ]
domain = "domain='%s'" % self._print(basis.domain)
order = "order='%s'" % self._print(basis.order)
args = [exprs] + gens + [domain, order]
return "%s(%s)" % (cls, ", ".join(args))
def _print_set(self, s):
items = sorted(s, key=default_sort_key)
args = ', '.join(self._print(item) for item in items)
if not args:
return "set()"
return '{%s}' % args
def _print_frozenset(self, s):
if not s:
return "frozenset()"
return "frozenset(%s)" % self._print_set(s)
def _print_Sum(self, expr):
def _xab_tostr(xab):
if len(xab) == 1:
return self._print(xab[0])
else:
return self._print((xab[0],) + tuple(xab[1:]))
L = ', '.join([_xab_tostr(l) for l in expr.limits])
return 'Sum(%s, %s)' % (self._print(expr.function), L)
def _print_Symbol(self, expr):
return expr.name
_print_MatrixSymbol = _print_Symbol
_print_RandomSymbol = _print_Symbol
def _print_Identity(self, expr):
return "I"
def _print_ZeroMatrix(self, expr):
return "0"
def _print_OneMatrix(self, expr):
return "1"
def _print_Predicate(self, expr):
return "Q.%s" % expr.name
def _print_str(self, expr):
return str(expr)
def _print_tuple(self, expr):
if len(expr) == 1:
return "(%s,)" % self._print(expr[0])
else:
return "(%s)" % self.stringify(expr, ", ")
def _print_Tuple(self, expr):
return self._print_tuple(expr)
def _print_Transpose(self, T):
return "%s.T" % self.parenthesize(T.arg, PRECEDENCE["Pow"])
def _print_Uniform(self, expr):
return "Uniform(%s, %s)" % (self._print(expr.a), self._print(expr.b))
def _print_Quantity(self, expr):
if self._settings.get("abbrev", False):
return "%s" % expr.abbrev
return "%s" % expr.name
def _print_Quaternion(self, expr):
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_Dimension(self, expr):
return str(expr)
def _print_Wild(self, expr):
return expr.name + '_'
def _print_WildFunction(self, expr):
return expr.name + '_'
def _print_WildDot(self, expr):
return expr.name
def _print_WildPlus(self, expr):
return expr.name
def _print_WildStar(self, expr):
return expr.name
def _print_Zero(self, expr):
if self._settings.get("sympy_integers", False):
return "S(0)"
return "0"
def _print_DMP(self, p):
from sympy.core.sympify import SympifyError
try:
if p.ring is not None:
# TODO incorporate order
return self._print(p.ring.to_sympy(p))
except SympifyError:
pass
cls = p.__class__.__name__
rep = self._print(p.rep)
dom = self._print(p.dom)
ring = self._print(p.ring)
return "%s(%s, %s, %s)" % (cls, rep, dom, ring)
def _print_DMF(self, expr):
return self._print_DMP(expr)
def _print_Object(self, obj):
return 'Object("%s")' % obj.name
def _print_IdentityMorphism(self, morphism):
return 'IdentityMorphism(%s)' % morphism.domain
def _print_NamedMorphism(self, morphism):
return 'NamedMorphism(%s, %s, "%s")' % \
(morphism.domain, morphism.codomain, morphism.name)
def _print_Category(self, category):
return 'Category("%s")' % category.name
def _print_Manifold(self, manifold):
return manifold.name.name
def _print_Patch(self, patch):
return patch.name.name
def _print_CoordSystem(self, coords):
return coords.name.name
def _print_BaseScalarField(self, field):
return field._coord_sys.symbols[field._index].name
def _print_BaseVectorField(self, field):
return 'e_%s' % field._coord_sys.symbols[field._index].name
def _print_Differential(self, diff):
field = diff._form_field
if hasattr(field, '_coord_sys'):
return 'd%s' % field._coord_sys.symbols[field._index].name
else:
return 'd(%s)' % self._print(field)
def _print_Tr(self, expr):
#TODO : Handle indices
return "%s(%s)" % ("Tr", self._print(expr.args[0]))
def _print_Str(self, s):
return self._print(s.name)
def _print_AppliedBinaryRelation(self, expr):
rel = expr.function
return '%s(%s, %s)' % (self._print(rel),
self._print(expr.lhs),
self._print(expr.rhs))
@print_function(StrPrinter)
def sstr(expr, **settings):
"""Returns the expression as a string.
For large expressions where speed is a concern, use the setting
order='none'. If abbrev=True setting is used then units are printed in
abbreviated form.
Examples
========
>>> from sympy import symbols, Eq, sstr
>>> a, b = symbols('a b')
>>> sstr(Eq(a + b, 0))
'Eq(a + b, 0)'
"""
p = StrPrinter(settings)
s = p.doprint(expr)
return s
class StrReprPrinter(StrPrinter):
"""(internal) -- see sstrrepr"""
def _print_str(self, s):
return repr(s)
def _print_Str(self, s):
# Str does not to be printed same as str here
return "%s(%s)" % (s.__class__.__name__, self._print(s.name))
@print_function(StrReprPrinter)
def sstrrepr(expr, **settings):
"""return expr in mixed str/repr form
i.e. strings are returned in repr form with quotes, and everything else
is returned in str form.
This function could be useful for hooking into sys.displayhook
"""
p = StrReprPrinter(settings)
s = p.doprint(expr)
return s
|
4cac41e83b8f85448d467de48634bdba6500ad21d839596b865b2b7bfdaf9e54 | """
A Printer which converts an expression into its LaTeX equivalent.
"""
from typing import Any, Dict
import itertools
from sympy.core import Add, Float, Mod, Mul, Number, S, Symbol
from sympy.core.alphabets import greeks
from sympy.core.containers import Tuple
from sympy.core.function import _coeff_isneg, AppliedUndef, Derivative
from sympy.core.operations import AssocOp
from sympy.core.sympify import SympifyError
from sympy.logic.boolalg import true
# sympy.printing imports
from sympy.printing.precedence import precedence_traditional
from sympy.printing.printer import Printer, print_function
from sympy.printing.conventions import split_super_sub, requires_partial
from sympy.printing.precedence import precedence, PRECEDENCE
import mpmath.libmp as mlib
from mpmath.libmp import prec_to_dps
from sympy.core.compatibility import default_sort_key
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 = {'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
)
def latex_escape(s):
"""
Escape a string such that latex interprets it as plaintext.
We can't use verbatim easily with mathjax, so escaping is easier.
Rules from https://tex.stackexchange.com/a/34586/41112.
"""
s = s.replace('\\', r'\textbackslash')
for c in '&%$#_{}':
s = s.replace(c, '\\' + c)
s = s.replace('~', r'\textasciitilde')
s = s.replace('^', r'\textasciicircum')
return s
class LatexPrinter(Printer):
printmethod = "_latex"
_default_settings = {
"full_prec": False,
"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": {},
"root_notation": True,
"mat_symbol_style": "plain",
"imaginary_unit": "i",
"gothic_re_im": False,
"decimal_separator": "period",
"perm_cyclic": True,
"parenthesize_super": True,
"min": None,
"max": None,
} # type: Dict[str, Any]
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 = {'(': ')', '[': ']'}
imaginary_unit_table = {
None: r"i",
"i": r"i",
"ri": r"\mathrm{i}",
"ti": r"\text{i}",
"j": r"j",
"rj": r"\mathrm{j}",
"tj": r"\text{j}",
}
try:
self._settings['imaginary_unit_latex'] = \
imaginary_unit_table[self._settings['imaginary_unit']]
except KeyError:
self._settings['imaginary_unit_latex'] = \
self._settings['imaginary_unit']
def _add_parens(self, s):
return r"\left({}\right)".format(s)
# TODO: merge this with the above, which requires a lot of test changes
def _add_parens_lspace(self, s):
return r"\left( {}\right)".format(s)
def parenthesize(self, item, level, is_neg=False, strict=False):
prec_val = precedence_traditional(item)
if is_neg and strict:
return self._add_parens(self._print(item))
if (prec_val < level) or ((not strict) and prec_val <= level):
return self._add_parens(self._print(item))
else:
return self._print(item)
def parenthesize_super(self, s):
"""
Protect superscripts in s
If the parenthesize_super option is set, protect with parentheses, else
wrap in braces.
"""
if "^" in s:
if self._settings['parenthesize_super']:
return self._add_parens(s)
else:
return "{{{}}}".format(s)
return s
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, 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):
ls = [self._print(o) for o in expr.args]
return self._deal_with_super_sub(expr.__class__.__name__) + \
r"\left(%s\right)" % ", ".join(ls)
def _print_bool(self, e):
return r"\text{%s}" % e
_print_BooleanTrue = _print_bool
_print_BooleanFalse = _print_bool
def _print_NoneType(self, e):
return r"\text{%s}" % e
def _print_Add(self, expr, order=None):
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
def _print_Permutation(self, expr):
from sympy.combinatorics.permutations import Permutation
from sympy.utilities.exceptions import SymPyDeprecationWarning
perm_cyclic = Permutation.print_cyclic
if perm_cyclic is not None:
SymPyDeprecationWarning(
feature="Permutation.print_cyclic = {}".format(perm_cyclic),
useinstead="init_printing(perm_cyclic={})"
.format(perm_cyclic),
issue=15201,
deprecated_since_version="1.6").warn()
else:
perm_cyclic = self._settings.get("perm_cyclic", True)
if perm_cyclic:
return self._print_Cycle(expr)
if expr.size == 0:
return r"\left( \right)"
lower = [self._print(arg) for arg in expr.array_form]
upper = [self._print(arg) for arg in range(len(lower))]
row1 = " & ".join(upper)
row2 = " & ".join(lower)
mat = r" \\ ".join((row1, row2))
return r"\begin{pmatrix} %s \end{pmatrix}" % mat
def _print_AppliedPermutation(self, expr):
perm, var = expr.args
return r"\sigma_{%s}(%s)" % (self._print(perm), self._print(var))
def _print_Float(self, expr):
# Based off of that in StrPrinter
dps = prec_to_dps(expr._prec)
strip = False if self._settings['full_prec'] else True
low = self._settings["min"] if "min" in self._settings else None
high = self._settings["max"] if "max" in self._settings else None
str_real = mlib.to_str(expr._mpf_, dps, strip_zeros=strip, min_fixed=low, max_fixed=high)
# 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:]
if self._settings['decimal_separator'] == 'comma':
mant = mant.replace('.','{,}')
return r"%s%s10^{%s}" % (mant, separator, exp)
elif str_real == "+inf":
return r"\infty"
elif str_real == "-inf":
return r"- \infty"
else:
if self._settings['decimal_separator'] == 'comma':
str_real = str_real.replace('.','{,}')
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 %s" % self.parenthesize(func, PRECEDENCE['Mul'])
def _print_Laplacian(self, expr):
func = expr._expr
return r"\triangle %s" % self.parenthesize(func, PRECEDENCE['Mul'])
def _print_Mul(self, expr):
from sympy.core.power import Pow
from sympy.physics.units import Quantity
from sympy.simplify import fraction
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:
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)))
return convert_args(args)
def convert_args(args):
_tex = last_term_tex = ""
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
# Check for unevaluated Mul. In this case we need to make sure the
# identities are visible, multiple Rational factors are not combined
# etc so we display in a straight-forward form that fully preserves all
# args and their order.
# XXX: _print_Pow calls this routine with instances of Pow...
if isinstance(expr, Mul):
args = expr.args
if args[0] is S.One or any(isinstance(arg, Number) for arg in args[1:]):
return convert_args(args)
include_parens = False
if _coeff_isneg(expr):
expr = -expr
tex = "- "
if expr.is_Add:
tex += "("
include_parens = True
else:
tex = ""
numer, denom = fraction(expr, exact=True)
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 \
and self._settings['root_notation']:
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 = self.parenthesize(expr.base, PRECEDENCE['Pow'])
p, q = expr.exp.p, expr.exp.q
# issue #12886: add parentheses for superscripts raised to powers
if expr.base.is_Symbol:
base = self.parenthesize_super(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}"
return self._helper_print_standard_power(expr, tex)
def _helper_print_standard_power(self, expr, template):
exp = self._print(expr.exp)
# issue #12886: add parentheses around superscripts raised
# to powers
base = self.parenthesize(expr.base, PRECEDENCE['Pow'])
if expr.base.is_Symbol:
base = self.parenthesize_super(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 template % (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 = '(' + self._print(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.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.parenthesize_super(self._print(x)),
self._print(num))
if dim == 1:
tex = r"\frac{%s}{%s}" % (diff_symbol, tex)
else:
tex = r"\frac{%s^{%s}}{%s}" % (diff_symbol, self._print(dim), tex)
if any(_coeff_isneg(i) for i in expr.args):
return r"%s %s" % (tex, self.parenthesize(expr.expr,
PRECEDENCE["Mul"],
is_neg=True,
strict=True))
return r"%s %s" % (tex, self.parenthesize(expr.expr,
PRECEDENCE["Mul"],
is_neg=False,
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"],
is_neg=any(_coeff_isneg(i) for i in expr.args),
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",
"asinh", "acosh", "atanh",
"acsch", "asech", "acoth",
]
# If the function is an inverse trig function, handle the style
if func in inv_trig_table:
if inv_trig_style == "abbreviated":
pass
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:
func_tex = self._hprint_Function(func)
func_tex = self.parenthesize_super(func_tex)
name = r'%s^{%s}' % (func_tex, 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))
def _print_ElementwiseApplyFunction(self, expr):
return r"{%s}_{\circ}\left({%s}\right)" % (
self._print(expr.function),
self._print(expr.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))
tex = r"\left( %s \mapsto %s \right)" % (symbols, self._print(expr))
return tex
def _print_IdentityFunction(self, expr):
return r"\left( x \mapsto x \right)"
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)" % (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):
if self._settings['gothic_re_im']:
tex = r"\Re{%s}" % self.parenthesize(expr.args[0], PRECEDENCE['Atom'])
else:
tex = r"\operatorname{{re}}{{{}}}".format(self.parenthesize(expr.args[0], PRECEDENCE['Atom']))
return self._do_exponent(tex, exp)
def _print_im(self, expr, exp=None):
if self._settings['gothic_re_im']:
tex = r"\Im{%s}" % self.parenthesize(expr.args[0], PRECEDENCE['Atom'])
else:
tex = r"\operatorname{{im}}{{{}}}".format(self.parenthesize(expr.args[0], PRECEDENCE['Atom']))
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 \left(%s\right)" % 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_Exp1(self, expr, exp=None):
return "e"
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_betainc(self, expr, exp=None, operator='B'):
largs = [self._print(arg) for arg in expr.args]
tex = r"\left(%s, %s\right)" % (largs[0], largs[1])
if exp is not None:
return r"\operatorname{%s}_{(%s, %s)}^{%s}%s" % (operator, largs[2], largs[3], exp, tex)
else:
return r"\operatorname{%s}_{(%s, %s)}%s" % (operator, largs[2], largs[3], tex)
def _print_betainc_regularized(self, expr, exp=None):
return self._print_betainc(expr, exp, operator='I')
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"\left(%s\right)^{%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, 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 not vec:
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, 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, 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" % (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" % (exp, tex)
return r"\zeta%s" % tex
def _print_stieltjes(self, expr, exp=None):
if len(expr.args) == 2:
tex = r"_{%s}\left(%s\right)" % tuple(map(self._print, expr.args))
else:
tex = r"_{%s}" % self._print(expr.args[0])
if exp is not None:
return r"\gamma%s^{%s}" % (tex, exp)
return r"\gamma%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" % (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, 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}" % (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}" % (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}" % (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}" % (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}" % (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}" % (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}" % (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}" % (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}" % (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}" % (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}" % (exp)
return tex
def __print_mathieu_functions(self, character, args, prime=False, exp=None):
a, q, z = map(self._print, args)
sup = r"^{\prime}" if prime else ""
exp = "" if not exp else "^{%s}" % exp
return r"%s%s\left(%s, %s, %s\right)%s" % (character, sup, a, q, z, exp)
def _print_mathieuc(self, expr, exp=None):
return self.__print_mathieu_functions("C", expr.args, exp=exp)
def _print_mathieus(self, expr, exp=None):
return self.__print_mathieu_functions("S", expr.args, exp=exp)
def _print_mathieucprime(self, expr, exp=None):
return self.__print_mathieu_functions("C", expr.args, prime=True, exp=exp)
def _print_mathieusprime(self, expr, exp=None):
return self.__print_mathieu_functions("S", expr.args, prime=True, exp=exp)
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 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, style='plain'):
if expr in self._settings['symbol_names']:
return self._settings['symbol_names'][expr]
return self._deal_with_super_sub(expr.name, style=style)
_print_RandomSymbol = _print_Symbol
def _deal_with_super_sub(self, string, style='plain'):
if '{' in string:
name, supers, subs = string, [], []
else:
name, supers, subs = split_super_sub(string)
name = translate(name)
supers = [translate(sup) for sup in supers]
subs = [translate(sub) for sub in subs]
# apply the style only to the name
if style == 'bold':
name = "\\mathbf{{{}}}".format(name)
# glue all items together:
if supers:
name += "^{%s}" % " ".join(supers)
if subs:
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)
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, dim):
x = list(x)
if x[2] == 1:
del x[2]
if x[0] == 0:
x[0] = None
if x[1] == dim:
x[1] = None
return ':'.join(self._print(xi) if xi is not None else '' for xi in x)
return (self.parenthesize(expr.parent, PRECEDENCE["Atom"], strict=True) + r'\left[' +
latexslice(expr.rowslice, expr.parent.rows) + ', ' +
latexslice(expr.colslice, expr.parent.cols) + 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.parenthesize(mat, precedence_traditional(expr), True)
def _print_Trace(self, expr):
mat = expr.arg
return r"\operatorname{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 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]),
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):
args = expr.args
prec = PRECEDENCE['Pow']
parens = self.parenthesize
return r' \circ '.join(
map(lambda arg: parens(arg, prec, strict=True), args))
def _print_HadamardPower(self, expr):
if precedence_traditional(expr.exp) < PRECEDENCE["Mul"]:
template = r"%s^{\circ \left({%s}\right)}"
else:
template = r"%s^{\circ {%s}}"
return self._helper_print_standard_power(expr, template)
def _print_KroneckerProduct(self, expr):
args = expr.args
prec = PRECEDENCE['Pow']
parens = self.parenthesize
return r' \otimes '.join(
map(lambda arg: parens(arg, prec, strict=True), args))
def _print_MatPow(self, expr):
base, exp = expr.base, expr.exp
from sympy.matrices import MatrixSymbol
if not isinstance(base, MatrixSymbol):
return "\\left(%s\\right)^{%s}" % (self._print(base),
self._print(exp))
else:
return "%s^{%s}" % (self._print(base), self._print(exp))
def _print_MatrixSymbol(self, expr):
return self._print_Symbol(expr, style=self._settings[
'mat_symbol_style'])
def _print_ZeroMatrix(self, Z):
return r"\mathbb{0}" if self._settings[
'mat_symbol_style'] == 'plain' else r"\mathbf{0}"
def _print_OneMatrix(self, O):
return r"\mathbb{1}" if self._settings[
'mat_symbol_style'] == 'plain' else r"\mathbf{1}"
def _print_Identity(self, I):
return r"\mathbb{I}" if self._settings[
'mat_symbol_style'] == 'plain' else r"\mathbf{I}"
def _print_PermutationMatrix(self, P):
perm_str = self._print(P.args[0])
return "P_{%s}" % perm_str
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
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])
)
def _print_PartialDerivative(self, expr):
if len(expr.variables) == 1:
return r"\frac{\partial}{\partial {%s}}{%s}" % (
self._print(expr.variables[0]),
self.parenthesize(expr.expr, PRECEDENCE["Mul"], False)
)
else:
return r"\frac{\partial^{%s}}{%s}{%s}" % (
len(expr.variables),
" ".join([r"\partial {%s}" % self._print(i) for i in expr.variables]),
self.parenthesize(expr.expr, PRECEDENCE["Mul"], False)
)
def _print_ArraySymbol(self, expr):
return self._print(expr.name)
def _print_ArrayElement(self, expr):
return "{{%s}_{%s}}" % (expr.name, ", ".join([f"{self._print(i)}" for i in expr.indices]))
def _print_UniversalSet(self, expr):
return r"\mathbb{U}"
def _print_frac(self, expr, exp=None):
if exp is None:
return r"\operatorname{frac}{\left(%s\right)}" % self._print(expr.args[0])
else:
return r"\operatorname{frac}{\left(%s\right)}^{%s}" % (
self._print(expr.args[0]), exp)
def _print_tuple(self, expr):
if self._settings['decimal_separator'] == 'comma':
sep = ";"
elif self._settings['decimal_separator'] == 'period':
sep = ","
else:
raise ValueError('Unknown Decimal Separator')
if len(expr) == 1:
# 1-tuple needs a trailing separator
return self._add_parens_lspace(self._print(expr[0]) + sep)
else:
return self._add_parens_lspace(
(sep + r" \ ").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):
if self._settings['decimal_separator'] == 'comma':
return r"\left[ %s\right]" % \
r"; \ ".join([self._print(i) for i in expr])
elif self._settings['decimal_separator'] == 'period':
return r"\left[ %s\right]" % \
r", \ ".join([self._print(i) for i in expr])
else:
raise ValueError('Unknown Decimal Separator')
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", \ ".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, exp=None):
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)
if exp is not None:
tex = r"{\left({\langle %s \rangle}^{%s}\right)}^{%s}" % (shift, power, exp)
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 is not None:
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_RandomDomain(self, d):
if hasattr(d, 'as_boolean'):
return '\\text{Domain: }' + self._print(d.as_boolean())
elif hasattr(d, 'set'):
return ('\\text{Domain: }' + self._print(d.symbols) + '\\text{ in }' +
self._print(d.set))
elif hasattr(d, 'symbols'):
return '\\text{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)
if self._settings['decimal_separator'] == 'comma':
items = "; ".join(map(self._print, items))
elif self._settings['decimal_separator'] == 'period':
items = ", ".join(map(self._print, items))
else:
raise ValueError('Unknown Decimal Separator')
return r"\left\{%s\right\}" % items
_print_frozenset = _print_set
def _print_Range(self, s):
dots = object()
if s.has(Symbol):
return self._print_Basic(s)
if s.start.is_infinite and s.stop.is_infinite:
if s.step.is_positive:
printset = dots, -1, 0, 1, dots
else:
printset = dots, 1, 0, -1, dots
elif s.start.is_infinite:
printset = dots, s[-1] - s.step, s[-1]
elif s.stop.is_infinite:
it = iter(s)
printset = next(it), next(it), dots
elif 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) if el is not dots else r'\ldots' for el in printset) +
r"\right\}")
def __print_number_polynomial(self, expr, letter, exp=None):
if len(expr.args) == 2:
if exp is not None:
return r"%s_{%s}^{%s}\left(%s\right)" % (letter,
self._print(expr.args[0]), exp,
self._print(expr.args[1]))
return r"%s_{%s}\left(%s\right)" % (letter,
self._print(expr.args[0]), self._print(expr.args[1]))
tex = r"%s_{%s}" % (letter, self._print(expr.args[0]))
if exp is not None:
tex = r"%s^{%s}" % (tex, exp)
return tex
def _print_bernoulli(self, expr, exp=None):
return self.__print_number_polynomial(expr, "B", exp)
def _print_bell(self, expr, exp=None):
if len(expr.args) == 3:
tex1 = r"B_{%s, %s}" % (self._print(expr.args[0]),
self._print(expr.args[1]))
tex2 = r"\left(%s\right)" % r", ".join(self._print(el) for
el in expr.args[2])
if exp is not None:
tex = r"%s^{%s}%s" % (tex1, exp, tex2)
else:
tex = tex1 + tex2
return tex
return self.__print_number_polynomial(expr, "B", exp)
def _print_fibonacci(self, expr, exp=None):
return self.__print_number_polynomial(expr, "F", exp)
def _print_lucas(self, expr, exp=None):
tex = r"L_{%s}" % self._print(expr.args[0])
if exp is not None:
tex = r"%s^{%s}" % (tex, exp)
return tex
def _print_tribonacci(self, expr, exp=None):
return self.__print_number_polynomial(expr, "T", exp)
def _print_SeqFormula(self, s):
dots = object()
if len(s.start.free_symbols) > 0 or len(s.stop.free_symbols) > 0:
return r"\left\{%s\right\}_{%s=%s}^{%s}" % (
self._print(s.formula),
self._print(s.variables[0]),
self._print(s.start),
self._print(s.stop)
)
if s.start is S.NegativeInfinity:
stop = s.stop
printset = (dots, 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(dots)
else:
printset = tuple(s)
return (r"\left[" +
r", ".join(self._print(el) if el is not dots else r'\ldots' 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):
prec = precedence_traditional(u)
args_str = [self.parenthesize(i, prec) for i in u.args]
return r" \cup ".join(args_str)
def _print_Complement(self, u):
prec = precedence_traditional(u)
args_str = [self.parenthesize(i, prec) for i in u.args]
return r" \setminus ".join(args_str)
def _print_Intersection(self, u):
prec = precedence_traditional(u)
args_str = [self.parenthesize(i, prec) for i in u.args]
return r" \cap ".join(args_str)
def _print_SymmetricDifference(self, u):
prec = precedence_traditional(u)
args_str = [self.parenthesize(i, prec) for i in u.args]
return r" \triangle ".join(args_str)
def _print_ProductSet(self, p):
prec = precedence_traditional(p)
if len(p.sets) >= 1 and not has_variety(p.sets):
return self.parenthesize(p.sets[0], prec) + "^{%d}" % len(p.sets)
return r" \times ".join(
self.parenthesize(set, prec) for set in p.sets)
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_Rationals(self, i):
return r"\mathbb{Q}"
def _print_Reals(self, i):
return r"\mathbb{R}"
def _print_Complexes(self, i):
return r"\mathbb{C}"
def _print_ImageSet(self, s):
expr = s.lamda.expr
sig = s.lamda.signature
xys = ((self._print(x), self._print(y)) for x, y in zip(sig, s.base_sets))
xinys = r" , ".join(r"%s \in %s" % xy for xy in xys)
return r"\left\{%s\; \middle|\; %s\right\}" % (self._print(expr), xinys)
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\; \middle|\; %s \right\}" % \
(vars_print, self._print(s.condition))
return r"\left\{%s\; \middle|\; %s \in %s \wedge %s \right\}" % (
vars_print,
vars_print,
self._print(s.base_set),
self._print(s.condition))
def _print_ComplexRegion(self, s):
vars_print = ', '.join([self._print(var) for var in s.variables])
return r"\left\{%s\; \middle|\; %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()) + 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, 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, exp)
return tex
def _print_UnifiedTransform(self, expr, s, inverse=False):
return r"\mathcal{{{}}}{}_{{{}}}\left[{}\right]\left({}\right)".format(s, '^{-1}' if inverse else '', self._print(expr.args[1]), self._print(expr.args[0]), self._print(expr.args[2]))
def _print_MellinTransform(self, expr):
return self._print_UnifiedTransform(expr, 'M')
def _print_InverseMellinTransform(self, expr):
return self._print_UnifiedTransform(expr, 'M', True)
def _print_LaplaceTransform(self, expr):
return self._print_UnifiedTransform(expr, 'L')
def _print_InverseLaplaceTransform(self, expr):
return self._print_UnifiedTransform(expr, 'L', True)
def _print_FourierTransform(self, expr):
return self._print_UnifiedTransform(expr, 'F')
def _print_InverseFourierTransform(self, expr):
return self._print_UnifiedTransform(expr, 'F', True)
def _print_SineTransform(self, expr):
return self._print_UnifiedTransform(expr, 'SIN')
def _print_InverseSineTransform(self, expr):
return self._print_UnifiedTransform(expr, 'SIN', True)
def _print_CosineTransform(self, expr):
return self._print_UnifiedTransform(expr, 'COS')
def _print_InverseCosineTransform(self, expr):
return self._print_UnifiedTransform(expr, 'COS', True)
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_LambertW(self, expr):
if len(expr.args) == 1:
return r"W\left(%s\right)" % self._print(expr.args[0])
return r"W_{%s}\left(%s\right)" % \
(self._print(expr.args[1]), self._print(expr.args[0]))
def _print_Morphism(self, morphism):
domain = self._print(morphism.domain)
codomain = self._print(morphism.codomain)
return "%s\\rightarrow %s" % (domain, codomain)
def _print_TransferFunction(self, expr):
num, den = self._print(expr.num), self._print(expr.den)
return r"\frac{%s}{%s}" % (num, den)
def _print_Series(self, expr):
args = list(expr.args)
parens = lambda x: self.parenthesize(x, precedence_traditional(expr),
False)
return ' '.join(map(parens, args))
def _print_MIMOSeries(self, expr):
from sympy.physics.control.lti import MIMOParallel
args = list(expr.args)[::-1]
parens = lambda x: self.parenthesize(x, precedence_traditional(expr),
False) if isinstance(x, MIMOParallel) else self._print(x)
return r"\cdot".join(map(parens, args))
def _print_Parallel(self, expr):
args = list(expr.args)
func = lambda x: self._print(x)
return ' + '.join(map(func, args))
def _print_MIMOParallel(self, expr):
args = list(expr.args)
func = lambda x: self._print(x)
return ' + '.join(map(func, args))
def _print_Feedback(self, expr):
from sympy.physics.control import TransferFunction, Parallel, Series
num, tf = expr.num, TransferFunction(1, 1, expr.num.var)
num_arg_list = list(num.args) if isinstance(num, Series) else [num]
den_arg_list = list(expr.den.args) if isinstance(expr.den, Series) else [expr.den]
if isinstance(num, Series) and isinstance(expr.den, Series):
den = Parallel(tf, Series(*num_arg_list, *den_arg_list))
elif isinstance(num, Series) and isinstance(expr.den, TransferFunction):
if expr.den == tf:
den = Parallel(tf, Series(*num_arg_list))
else:
den = Parallel(tf, Series(*num_arg_list, expr.den))
elif isinstance(num, TransferFunction) and isinstance(expr.den, Series):
if num == tf:
den = Parallel(tf, Series(*den_arg_list))
else:
den = Parallel(tf, Series(num, *den_arg_list))
else:
if num == tf:
den = Parallel(tf, *den_arg_list)
elif expr.den == tf:
den = Parallel(tf, *num_arg_list)
else:
den = Parallel(tf, Series(*num_arg_list, *den_arg_list))
numer = self._print(num)
denom = self._print(den)
return r"\frac{%s}{%s}" % (numer, denom)
def _print_TransferFunctionMatrix(self, expr):
mat = self._print(expr._expr_mat)
return r"%s_\tau" % mat
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 r"\mathbf{{{}}}".format(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 '{{{}}}^{{{}}}'.format(self._print(M.ring), self._print(M.rank))
def _print_FreeModuleElement(self, m):
# Print as row vector for convenience, for now.
return r"\left[ {} \right]".format(",".join(
'{' + self._print(x) + '}' for x in m))
def _print_SubModule(self, m):
return r"\left\langle {} \right\rangle".format(",".join(
'{' + self._print(x) + '}' for x in m.gens))
def _print_ModuleImplementedIdeal(self, m):
return r"\left\langle {} \right\rangle".format(",".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{{{}}}{{{}}}".format(self._print(R.ring),
self._print(R.base_ideal))
def _print_QuotientRingElement(self, x):
return r"{{{}}} + {{{}}}".format(self._print(x.data),
self._print(x.ring.base_ideal))
def _print_QuotientModuleElement(self, m):
return r"{{{}}} + {{{}}}".format(self._print(m.data),
self._print(m.module.killed_module))
def _print_QuotientModule(self, M):
# TODO nicer fractions for few generators...
return r"\frac{{{}}}{{{}}}".format(self._print(M.base),
self._print(M.killed_module))
def _print_MatrixHomomorphism(self, h):
return r"{{{}}} : {{{}}} \to {{{}}}".format(self._print(h._sympy_matrix()),
self._print(h.domain), self._print(h.codomain))
def _print_Manifold(self, manifold):
string = manifold.name.name
if '{' in string:
name, supers, subs = string, [], []
else:
name, supers, subs = split_super_sub(string)
name = translate(name)
supers = [translate(sup) for sup in supers]
subs = [translate(sub) for sub in subs]
name = r'\text{%s}' % name
if supers:
name += "^{%s}" % " ".join(supers)
if subs:
name += "_{%s}" % " ".join(subs)
return name
def _print_Patch(self, patch):
return r'\text{%s}_{%s}' % (self._print(patch.name), self._print(patch.manifold))
def _print_CoordSystem(self, coordsys):
return r'\text{%s}^{\text{%s}}_{%s}' % (
self._print(coordsys.name), self._print(coordsys.patch.name), self._print(coordsys.manifold)
)
def _print_CovarDerivativeOp(self, cvd):
return r'\mathbb{\nabla}_{%s}' % self._print(cvd._wrt)
def _print_BaseScalarField(self, field):
string = field._coord_sys.symbols[field._index].name
return r'\mathbf{{{}}}'.format(self._print(Symbol(string)))
def _print_BaseVectorField(self, field):
string = field._coord_sys.symbols[field._index].name
return r'\partial_{{{}}}'.format(self._print(Symbol(string)))
def _print_Differential(self, diff):
field = diff._form_field
if hasattr(field, '_coord_sys'):
string = field._coord_sys.symbols[field._index].name
return r'\operatorname{{d}}{}'.format(self._print(Symbol(string)))
else:
string = self._print(field)
return r'\operatorname{{d}}\left({}\right)'.format(string)
def _print_Tr(self, p):
# TODO: Handle indices
contents = self._print(p.args[0])
return r'\operatorname{{tr}}\left({}\right)'.format(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]), 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]), 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" % (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" % (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]), 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]), exp)
return r'\Omega\left(%s\right)' % self._print(expr.args[0])
def _print_Str(self, s):
return str(s.name)
def _print_float(self, expr):
return self._print(Float(expr))
def _print_int(self, expr):
return str(expr)
def _print_mpz(self, expr):
return str(expr)
def _print_mpq(self, expr):
return str(expr)
def _print_Predicate(self, expr):
return str(expr)
def _print_AppliedPredicate(self, expr):
pred = expr.function
args = expr.arguments
pred_latex = self._print(pred)
args_latex = ', '.join([self._print(a) for a in args])
return '%s(%s)' % (pred_latex, args_latex)
def emptyPrinter(self, expr):
# default to just printing as monospace, like would normally be shown
s = super().emptyPrinter(expr)
return r"\mathtt{\text{%s}}" % latex_escape(s)
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
@print_function(LatexPrinter)
def latex(expr, **settings):
r"""Convert the given expression to LaTeX string representation.
Parameters
==========
full_prec: boolean, optional
If set to True, a floating point number is printed with full precision.
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.
root_notation : boolean, optional
If set to ``False``, exponents of the form 1/n are printed in fractonal
form. Default is ``True``, to print exponent in root form.
mat_symbol_style : string, optional
Can be either ``plain`` (default) or ``bold``. If set to ``bold``,
a MatrixSymbol A will be printed as ``\mathbf{A}``, otherwise as ``A``.
imaginary_unit : string, optional
String to use for the imaginary unit. Defined options are "i" (default)
and "j". Adding "r" or "t" in front gives ``\mathrm`` or ``\text``, so
"ri" leads to ``\mathrm{i}`` which gives `\mathrm{i}`.
gothic_re_im : boolean, optional
If set to ``True``, `\Re` and `\Im` is used for ``re`` and ``im``, respectively.
The default is ``False`` leading to `\operatorname{re}` and `\operatorname{im}`.
decimal_separator : string, optional
Specifies what separator to use to separate the whole and fractional parts of a
floating point number as in `2.5` for the default, ``period`` or `2{,}5`
when ``comma`` is specified. Lists, sets, and tuple are printed with semicolon
separating the elements when ``comma`` is chosen. For example, [1; 2; 3] when
``comma`` is chosen and [1,2,3] for when ``period`` is chosen.
parenthesize_super : boolean, optional
If set to ``False``, superscripted expressions will not be parenthesized when
powered. Default is ``True``, which parenthesizes the expression when powered.
min: Integer or None, optional
Sets the lower bound for the exponent to print floating point numbers in
fixed-point format.
max: Integer or None, optional
Sets the upper bound for the exponent to print floating point numbers in
fixed-point format.
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 :class:`list`,
:class:`tuple`, and :class:`dict`:
>>> print(latex([2/x, y], mode='inline'))
$\left[ 2 / x, \ y\right]$
Unsupported types are rendered as monospaced plaintext:
>>> print(latex(int))
\mathtt{\text{<class 'int'>}}
>>> print(latex("plain % text"))
\mathtt{\text{plain \% text}}
See :ref:`printer_method_example` for an example of how to override
this behavior for your own types by implementing ``_latex``.
.. versionchanged:: 1.7.0
Unsupported types no longer have their ``str`` representation treated as valid latex.
"""
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))
def multiline_latex(lhs, rhs, terms_per_line=1, environment="align*", use_dots=False, **settings):
r"""
This function generates a LaTeX equation with a multiline right-hand side
in an ``align*``, ``eqnarray`` or ``IEEEeqnarray`` environment.
Parameters
==========
lhs : Expr
Left-hand side of equation
rhs : Expr
Right-hand side of equation
terms_per_line : integer, optional
Number of terms per line to print. Default is 1.
environment : "string", optional
Which LaTeX wnvironment to use for the output. Options are "align*"
(default), "eqnarray", and "IEEEeqnarray".
use_dots : boolean, optional
If ``True``, ``\\dots`` is added to the end of each line. Default is ``False``.
Examples
========
>>> from sympy import multiline_latex, symbols, sin, cos, exp, log, I
>>> x, y, alpha = symbols('x y alpha')
>>> expr = sin(alpha*y) + exp(I*alpha) - cos(log(y))
>>> print(multiline_latex(x, expr))
\begin{align*}
x = & e^{i \alpha} \\
& + \sin{\left(\alpha y \right)} \\
& - \cos{\left(\log{\left(y \right)} \right)}
\end{align*}
Using at most two terms per line:
>>> print(multiline_latex(x, expr, 2))
\begin{align*}
x = & e^{i \alpha} + \sin{\left(\alpha y \right)} \\
& - \cos{\left(\log{\left(y \right)} \right)}
\end{align*}
Using ``eqnarray`` and dots:
>>> print(multiline_latex(x, expr, terms_per_line=2, environment="eqnarray", use_dots=True))
\begin{eqnarray}
x & = & e^{i \alpha} + \sin{\left(\alpha y \right)} \dots\nonumber\\
& & - \cos{\left(\log{\left(y \right)} \right)}
\end{eqnarray}
Using ``IEEEeqnarray``:
>>> print(multiline_latex(x, expr, environment="IEEEeqnarray"))
\begin{IEEEeqnarray}{rCl}
x & = & e^{i \alpha} \nonumber\\
& & + \sin{\left(\alpha y \right)} \nonumber\\
& & - \cos{\left(\log{\left(y \right)} \right)}
\end{IEEEeqnarray}
Notes
=====
All optional parameters from ``latex`` can also be used.
"""
# Based on code from https://github.com/sympy/sympy/issues/3001
l = LatexPrinter(**settings)
if environment == "eqnarray":
result = r'\begin{eqnarray}' + '\n'
first_term = '& = &'
nonumber = r'\nonumber'
end_term = '\n\\end{eqnarray}'
doubleet = True
elif environment == "IEEEeqnarray":
result = r'\begin{IEEEeqnarray}{rCl}' + '\n'
first_term = '& = &'
nonumber = r'\nonumber'
end_term = '\n\\end{IEEEeqnarray}'
doubleet = True
elif environment == "align*":
result = r'\begin{align*}' + '\n'
first_term = '= &'
nonumber = ''
end_term = '\n\\end{align*}'
doubleet = False
else:
raise ValueError("Unknown environment: {}".format(environment))
dots = ''
if use_dots:
dots=r'\dots'
terms = rhs.as_ordered_terms()
n_terms = len(terms)
term_count = 1
for i in range(n_terms):
term = terms[i]
term_start = ''
term_end = ''
sign = '+'
if term_count > terms_per_line:
if doubleet:
term_start = '& & '
else:
term_start = '& '
term_count = 1
if term_count == terms_per_line:
# End of line
if i < n_terms-1:
# There are terms remaining
term_end = dots + nonumber + r'\\' + '\n'
else:
term_end = ''
if term.as_ordered_factors()[0] == -1:
term = -1*term
sign = r'-'
if i == 0: # beginning
if sign == '+':
sign = ''
result += r'{:s} {:s}{:s} {:s} {:s}'.format(l.doprint(lhs),
first_term, sign, l.doprint(term), term_end)
else:
result += r'{:s}{:s} {:s} {:s}'.format(term_start, sign,
l.doprint(term), term_end)
term_count += 1
result += end_term
return result
|
008c1b062f33e96230c0d532cc3386e714148cd06b13d0f9f619c794f31f7d12 | """
Mathematica code printer
"""
from typing import Any, Dict, Set, Tuple
from sympy.core import Basic, Expr, Float
from sympy.printing.codeprinter import CodePrinter
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")],
"sec": [(lambda x: True, "Sec")],
"csc": [(lambda x: True, "Csc")],
"asin": [(lambda x: True, "ArcSin")],
"acos": [(lambda x: True, "ArcCos")],
"atan": [(lambda x: True, "ArcTan")],
"acot": [(lambda x: True, "ArcCot")],
"asec": [(lambda x: True, "ArcSec")],
"acsc": [(lambda x: True, "ArcCsc")],
"atan2": [(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")],
"erf": [(lambda x: True, "Erf")],
"erf2": [(lambda *x: True, "Erf")],
"erfc": [(lambda x: True, "Erfc")],
"erfi": [(lambda x: True, "Erfi")],
"erfinv": [(lambda x: True, "InverseErf")],
"erfcinv": [(lambda x: True, "InverseErfc")],
"erf2inv": [(lambda *x: True, "InverseErf")],
"expint": [(lambda *x: True, "ExpIntegralE")],
"Ei": [(lambda x: True, "ExpIntegralEi")],
"fresnelc": [(lambda x: True, "FresnelC")],
"fresnels": [(lambda x: True, "FresnelS")],
"gamma": [(lambda x: True, "Gamma")],
"uppergamma": [(lambda *x: True, "Gamma")],
"polygamma": [(lambda *x: True, "PolyGamma")],
"loggamma": [(lambda x: True, "LogGamma")],
"beta": [(lambda *x: True, "Beta")],
"Ci": [(lambda x: True, "CosIntegral")],
"Si": [(lambda x: True, "SinIntegral")],
"Chi": [(lambda x: True, "CoshIntegral")],
"Shi": [(lambda x: True, "SinhIntegral")],
"li": [(lambda x: True, "LogIntegral")],
"factorial": [(lambda x: True, "Factorial")],
"factorial2": [(lambda x: True, "Factorial2")],
"subfactorial": [(lambda x: True, "Subfactorial")],
"catalan": [(lambda x: True, "CatalanNumber")],
"harmonic": [(lambda *x: True, "HarmonicNumber")],
"RisingFactorial": [(lambda *x: True, "Pochhammer")],
"FallingFactorial": [(lambda *x: True, "FactorialPower")],
"laguerre": [(lambda *x: True, "LaguerreL")],
"assoc_laguerre": [(lambda *x: True, "LaguerreL")],
"hermite": [(lambda *x: True, "HermiteH")],
"jacobi": [(lambda *x: True, "JacobiP")],
"gegenbauer": [(lambda *x: True, "GegenbauerC")],
"chebyshevt": [(lambda *x: True, "ChebyshevT")],
"chebyshevu": [(lambda *x: True, "ChebyshevU")],
"legendre": [(lambda *x: True, "LegendreP")],
"assoc_legendre": [(lambda *x: True, "LegendreP")],
"mathieuc": [(lambda *x: True, "MathieuC")],
"mathieus": [(lambda *x: True, "MathieuS")],
"mathieucprime": [(lambda *x: True, "MathieuCPrime")],
"mathieusprime": [(lambda *x: True, "MathieuSPrime")],
"stieltjes": [(lambda x: True, "StieltjesGamma")],
"elliptic_e": [(lambda *x: True, "EllipticE")],
"elliptic_f": [(lambda *x: True, "EllipticE")],
"elliptic_k": [(lambda x: True, "EllipticK")],
"elliptic_pi": [(lambda *x: True, "EllipticPi")],
"zeta": [(lambda *x: True, "Zeta")],
"besseli": [(lambda *x: True, "BesselI")],
"besselj": [(lambda *x: True, "BesselJ")],
"besselk": [(lambda *x: True, "BesselK")],
"bessely": [(lambda *x: True, "BesselY")],
"hankel1": [(lambda *x: True, "HankelH1")],
"hankel2": [(lambda *x: True, "HankelH2")],
"airyai": [(lambda x: True, "AiryAi")],
"airybi": [(lambda x: True, "AiryBi")],
"airyaiprime": [(lambda x: True, "AiryAiPrime")],
"airybiprime": [(lambda x: True, "AiryBiPrime")],
"polylog": [(lambda *x: True, "PolyLog")],
"lerchphi": [(lambda *x: True, "LerchPhi")],
"gcd": [(lambda *x: True, "GCD")],
"lcm": [(lambda *x: True, "LCM")],
"jn": [(lambda *x: True, "SphericalBesselJ")],
"yn": [(lambda *x: True, "SphericalBesselY")],
"hyper": [(lambda *x: True, "HypergeometricPFQ")],
"meijerg": [(lambda *x: True, "MeijerG")],
"appellf1": [(lambda *x: True, "AppellF1")],
"DiracDelta": [(lambda x: True, "DiracDelta")],
"Heaviside": [(lambda x: True, "HeavisideTheta")],
"KroneckerDelta": [(lambda *x: True, "KroneckerDelta")],
}
class MCodePrinter(CodePrinter):
"""A printer to convert python expressions to
strings of the Wolfram's Mathematica code
"""
printmethod = "_mcode"
language = "Wolfram Language"
_default_settings = {
'order': None,
'full_prec': 'auto',
'precision': 15,
'user_functions': {},
'human': True,
'allow_unknown_functions': False,
} # type: Dict[str, Any]
_number_symbols = set() # type: Set[Tuple[Expr, Float]]
_not_supported = set() # type: Set[Basic]
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', {}).copy()
for k, v in userfuncs.items():
if not isinstance(v, list):
userfuncs[k] = [(lambda *x: True, v)]
self.known_functions.update(userfuncs)
def _format_code(self, lines):
return lines
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()._print_Mul(expr.func(*c))
if nc:
res += '*'
res += '**'.join(self.parenthesize(a, PREC) for a in nc)
return res
def _print_Relational(self, expr):
lhs_code = self._print(expr.lhs)
rhs_code = self._print(expr.rhs)
op = expr.rel_op
return "{} {} {}".format(lhs_code, op, rhs_code)
# Primitive numbers
def _print_Zero(self, expr):
return '0'
def _print_One(self, expr):
return '1'
def _print_NegativeOne(self, expr):
return '-1'
def _print_Half(self, expr):
return '1/2'
def _print_ImaginaryUnit(self, expr):
return 'I'
# Infinity and invalid numbers
def _print_Infinity(self, expr):
return 'Infinity'
def _print_NegativeInfinity(self, expr):
return '-Infinity'
def _print_ComplexInfinity(self, expr):
return 'ComplexInfinity'
def _print_NaN(self, expr):
return 'Indeterminate'
# Mathematical constants
def _print_Exp1(self, expr):
return 'E'
def _print_Pi(self, expr):
return 'Pi'
def _print_GoldenRatio(self, expr):
return 'GoldenRatio'
def _print_TribonacciConstant(self, expr):
expanded = expr.expand(func=True)
PREC = precedence(expr)
return self.parenthesize(expanded, PREC)
def _print_EulerGamma(self, expr):
return 'EulerGamma'
def _print_Catalan(self, expr):
return 'Catalan'
def _print_list(self, expr):
return '{' + ', '.join(self.doprint(a) for a in expr) + '}'
_print_tuple = _print_list
_print_Tuple = _print_list
def _print_ImmutableDenseMatrix(self, expr):
return self.doprint(expr.tolist())
def _print_ImmutableSparseMatrix(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():
items = sorted(expr.todok().items(), key=default_sort_key)
return '{' + \
', '.join(print_rule(k, v) for k, v in items) + \
'}'
def print_dims():
return self.doprint(expr.shape)
return 'SparseArray[{}, {}]'.format(print_data(), print_dims())
def _print_ImmutableDenseNDimArray(self, expr):
return self.doprint(expr.tolist())
def _print_ImmutableSparseNDimArray(self, expr):
def print_string_list(string_list):
return '{' + ', '.join(a for a in string_list) + '}'
def to_mathematica_index(*args):
"""Helper function to change Python style indexing to
Pathematica indexing.
Python indexing (0, 1 ... n-1)
-> Mathematica indexing (1, 2 ... n)
"""
return tuple(i + 1 for i in args)
def print_rule(pos, val):
"""Helper function to print a rule of Mathematica"""
return '{} -> {}'.format(self.doprint(pos), self.doprint(val))
def print_data():
"""Helper function to print data part of Mathematica
sparse array.
It uses the fourth notation ``SparseArray[data,{d1,d2,...}]``
from
https://reference.wolfram.com/language/ref/SparseArray.html
``data`` must be formatted with rule.
"""
return print_string_list(
[print_rule(
to_mathematica_index(*(expr._get_tuple_index(key))),
value)
for key, value in sorted(expr._sparse_array.items())]
)
def print_dims():
"""Helper function to print dimensions part of Mathematica
sparse array.
It uses the fourth notation ``SparseArray[data,{d1,d2,...}]``
from
https://reference.wolfram.com/language/ref/SparseArray.html
"""
return self.doprint(expr.shape)
return 'SparseArray[{}, {}]'.format(print_data(), print_dims())
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, ", "))
elif (expr.func.__name__ in self._rewriteable_functions and
self._rewriteable_functions[expr.func.__name__] in self.known_functions):
# Simple rewrite to supported function possible
return self._print(expr.rewrite(self._rewriteable_functions[expr.func.__name__]))
return expr.func.__name__ + "[%s]" % self.stringify(expr.args, ", ")
_print_MinMaxBase = _print_Function
def _print_LambertW(self, expr):
if len(expr.args) == 1:
return "ProductLog[{}]".format(self._print(expr.args[0]))
return "ProductLog[{}, {}]".format(
self._print(expr.args[1]), self._print(expr.args[0]))
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 _get_comment(self, text):
return "(* {} *)".format(text)
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)
|
ac35b6c0a686e3e1ed59ed799f50b69075620e181a0f081a539769e4982f3719 | """Integration method that emulates by-hand techniques.
This module also provides functionality to get the steps used to evaluate a
particular integral, in the ``integral_steps`` function. This will return
nested namedtuples representing the integration rules used. The
``manualintegrate`` function computes the integral using those steps given
an integrand; given the steps, ``_manualintegrate`` will evaluate them.
The integrator can be extended with new heuristics and evaluation
techniques. To do so, write a function that accepts an ``IntegralInfo``
object and returns either a namedtuple representing a rule or
``None``. Then, write another function that accepts the namedtuple's fields
and returns the antiderivative, and decorate it with
``@evaluates(namedtuple_type)``. If the new technique requires a new
match, add the key and call to the antiderivative function to integral_steps.
To enable simple substitutions, add the match to find_substitutions.
"""
from typing import Dict as tDict, Optional
from collections import namedtuple, defaultdict
from collections.abc import Mapping
from functools import reduce
import sympy
from sympy.core.compatibility import iterable
from sympy.core.containers import Dict
from sympy.core.expr import Expr
from sympy.core.logic import fuzzy_not
from sympy.functions.elementary.trigonometric import TrigonometricFunction
from sympy.functions.special.polynomials import OrthogonalPolynomial
from sympy.functions.elementary.piecewise import Piecewise
from sympy.strategies.core import switch, do_one, null_safe, condition
from sympy.core.relational import Eq, Ne
from sympy.polys.polytools import degree
from sympy.ntheory.factor_ import divisors
from sympy.utilities.misc import debug
ZERO = sympy.S.Zero
def Rule(name, props=""):
# GOTCHA: namedtuple class name not considered!
def __eq__(self, other):
return self.__class__ == other.__class__ and tuple.__eq__(self, other)
__neq__ = lambda self, other: not __eq__(self, other)
cls = namedtuple(name, props + " context symbol")
cls.__eq__ = __eq__
cls.__ne__ = __neq__
return cls
ConstantRule = Rule("ConstantRule", "constant")
ConstantTimesRule = Rule("ConstantTimesRule", "constant other substep")
PowerRule = Rule("PowerRule", "base exp")
AddRule = Rule("AddRule", "substeps")
URule = Rule("URule", "u_var u_func constant substep")
PartsRule = Rule("PartsRule", "u dv v_step second_step")
CyclicPartsRule = Rule("CyclicPartsRule", "parts_rules coefficient")
TrigRule = Rule("TrigRule", "func arg")
ExpRule = Rule("ExpRule", "base exp")
ReciprocalRule = Rule("ReciprocalRule", "func")
ArcsinRule = Rule("ArcsinRule")
InverseHyperbolicRule = Rule("InverseHyperbolicRule", "func")
AlternativeRule = Rule("AlternativeRule", "alternatives")
DontKnowRule = Rule("DontKnowRule")
DerivativeRule = Rule("DerivativeRule")
RewriteRule = Rule("RewriteRule", "rewritten substep")
PiecewiseRule = Rule("PiecewiseRule", "subfunctions")
HeavisideRule = Rule("HeavisideRule", "harg ibnd substep")
TrigSubstitutionRule = Rule("TrigSubstitutionRule",
"theta func rewritten substep restriction")
ArctanRule = Rule("ArctanRule", "a b c")
ArccothRule = Rule("ArccothRule", "a b c")
ArctanhRule = Rule("ArctanhRule", "a b c")
JacobiRule = Rule("JacobiRule", "n a b")
GegenbauerRule = Rule("GegenbauerRule", "n a")
ChebyshevTRule = Rule("ChebyshevTRule", "n")
ChebyshevURule = Rule("ChebyshevURule", "n")
LegendreRule = Rule("LegendreRule", "n")
HermiteRule = Rule("HermiteRule", "n")
LaguerreRule = Rule("LaguerreRule", "n")
AssocLaguerreRule = Rule("AssocLaguerreRule", "n a")
CiRule = Rule("CiRule", "a b")
ChiRule = Rule("ChiRule", "a b")
EiRule = Rule("EiRule", "a b")
SiRule = Rule("SiRule", "a b")
ShiRule = Rule("ShiRule", "a b")
ErfRule = Rule("ErfRule", "a b c")
FresnelCRule = Rule("FresnelCRule", "a b c")
FresnelSRule = Rule("FresnelSRule", "a b c")
LiRule = Rule("LiRule", "a b")
PolylogRule = Rule("PolylogRule", "a b")
UpperGammaRule = Rule("UpperGammaRule", "a e")
EllipticFRule = Rule("EllipticFRule", "a d")
EllipticERule = Rule("EllipticERule", "a d")
IntegralInfo = namedtuple('IntegralInfo', 'integrand symbol')
evaluators = {}
def evaluates(rule):
def _evaluates(func):
func.rule = rule
evaluators[rule] = func
return func
return _evaluates
def contains_dont_know(rule):
if isinstance(rule, DontKnowRule):
return True
else:
for val in rule:
if isinstance(val, tuple):
if contains_dont_know(val):
return True
elif isinstance(val, list):
if any(contains_dont_know(i) for i in val):
return True
return False
def manual_diff(f, symbol):
"""Derivative of f in form expected by find_substitutions
SymPy's derivatives for some trig functions (like cot) aren't in a form
that works well with finding substitutions; this replaces the
derivatives for those particular forms with something that works better.
"""
if f.args:
arg = f.args[0]
if isinstance(f, sympy.tan):
return arg.diff(symbol) * sympy.sec(arg)**2
elif isinstance(f, sympy.cot):
return -arg.diff(symbol) * sympy.csc(arg)**2
elif isinstance(f, sympy.sec):
return arg.diff(symbol) * sympy.sec(arg) * sympy.tan(arg)
elif isinstance(f, sympy.csc):
return -arg.diff(symbol) * sympy.csc(arg) * sympy.cot(arg)
elif isinstance(f, sympy.Add):
return sum([manual_diff(arg, symbol) for arg in f.args])
elif isinstance(f, sympy.Mul):
if len(f.args) == 2 and isinstance(f.args[0], sympy.Number):
return f.args[0] * manual_diff(f.args[1], symbol)
return f.diff(symbol)
def manual_subs(expr, *args):
"""
A wrapper for `expr.subs(*args)` with additional logic for substitution
of invertible functions.
"""
if len(args) == 1:
sequence = args[0]
if isinstance(sequence, (Dict, Mapping)):
sequence = sequence.items()
elif not iterable(sequence):
raise ValueError("Expected an iterable of (old, new) pairs")
elif len(args) == 2:
sequence = [args]
else:
raise ValueError("subs accepts either 1 or 2 arguments")
new_subs = []
for old, new in sequence:
if isinstance(old, sympy.log):
# If log(x) = y, then exp(a*log(x)) = exp(a*y)
# that is, x**a = exp(a*y). Replace nontrivial powers of x
# before subs turns them into `exp(y)**a`, but
# do not replace x itself yet, to avoid `log(exp(y))`.
x0 = old.args[0]
expr = expr.replace(lambda x: x.is_Pow and x.base == x0,
lambda x: sympy.exp(x.exp*new))
new_subs.append((x0, sympy.exp(new)))
return expr.subs(list(sequence) + new_subs)
# Method based on that on SIN, described in "Symbolic Integration: The
# Stormy Decade"
inverse_trig_functions = (sympy.atan, sympy.asin, sympy.acos, sympy.acot, sympy.acsc, sympy.asec)
def find_substitutions(integrand, symbol, u_var):
results = []
def test_subterm(u, u_diff):
if u_diff == 0:
return False
substituted = integrand / u_diff
if symbol not in substituted.free_symbols:
# replaced everything already
return False
debug("substituted: {}, u: {}, u_var: {}".format(substituted, u, u_var))
substituted = manual_subs(substituted, u, u_var).cancel()
if symbol not in substituted.free_symbols:
# avoid increasing the degree of a rational function
if integrand.is_rational_function(symbol) and substituted.is_rational_function(u_var):
deg_before = max([degree(t, symbol) for t in integrand.as_numer_denom()])
deg_after = max([degree(t, u_var) for t in substituted.as_numer_denom()])
if deg_after > deg_before:
return False
return substituted.as_independent(u_var, as_Add=False)
# special treatment for substitutions u = (a*x+b)**(1/n)
if (isinstance(u, sympy.Pow) and (1/u.exp).is_Integer and
sympy.Abs(u.exp) < 1):
a = sympy.Wild('a', exclude=[symbol])
b = sympy.Wild('b', exclude=[symbol])
match = u.base.match(a*symbol + b)
if match:
a, b = [match.get(i, ZERO) for i in (a, b)]
if a != 0 and b != 0:
substituted = substituted.subs(symbol,
(u_var**(1/u.exp) - b)/a)
return substituted.as_independent(u_var, as_Add=False)
return False
def possible_subterms(term):
if isinstance(term, (TrigonometricFunction,
*inverse_trig_functions,
sympy.exp, sympy.log, sympy.Heaviside)):
return [term.args[0]]
elif isinstance(term, (sympy.chebyshevt, sympy.chebyshevu,
sympy.legendre, sympy.hermite, sympy.laguerre)):
return [term.args[1]]
elif isinstance(term, (sympy.gegenbauer, sympy.assoc_laguerre)):
return [term.args[2]]
elif isinstance(term, sympy.jacobi):
return [term.args[3]]
elif isinstance(term, sympy.Mul):
r = []
for u in term.args:
r.append(u)
r.extend(possible_subterms(u))
return r
elif isinstance(term, sympy.Pow):
r = []
if term.args[1].is_constant(symbol):
r.append(term.args[0])
elif term.args[0].is_constant(symbol):
r.append(term.args[1])
if term.args[1].is_Integer:
r.extend([term.args[0]**d for d in divisors(term.args[1])
if 1 < d < abs(term.args[1])])
if term.args[0].is_Add:
r.extend([t for t in possible_subterms(term.args[0])
if t.is_Pow])
return r
elif isinstance(term, sympy.Add):
r = []
for arg in term.args:
r.append(arg)
r.extend(possible_subterms(arg))
return r
return []
for u in possible_subterms(integrand):
if u == symbol:
continue
u_diff = manual_diff(u, symbol)
new_integrand = test_subterm(u, u_diff)
if new_integrand is not False:
constant, new_integrand = new_integrand
if new_integrand == integrand.subs(symbol, u_var):
continue
substitution = (u, constant, new_integrand)
if substitution not in results:
results.append(substitution)
return results
def rewriter(condition, rewrite):
"""Strategy that rewrites an integrand."""
def _rewriter(integral):
integrand, symbol = integral
debug("Integral: {} is rewritten with {} on symbol: {}".format(integrand, rewrite, symbol))
if condition(*integral):
rewritten = rewrite(*integral)
if rewritten != integrand:
substep = integral_steps(rewritten, symbol)
if not isinstance(substep, DontKnowRule) and substep:
return RewriteRule(
rewritten,
substep,
integrand, symbol)
return _rewriter
def proxy_rewriter(condition, rewrite):
"""Strategy that rewrites an integrand based on some other criteria."""
def _proxy_rewriter(criteria):
criteria, integral = criteria
integrand, symbol = integral
debug("Integral: {} is rewritten with {} on symbol: {} and criteria: {}".format(integrand, rewrite, symbol, criteria))
args = criteria + list(integral)
if condition(*args):
rewritten = rewrite(*args)
if rewritten != integrand:
return RewriteRule(
rewritten,
integral_steps(rewritten, symbol),
integrand, symbol)
return _proxy_rewriter
def multiplexer(conditions):
"""Apply the rule that matches the condition, else None"""
def multiplexer_rl(expr):
for key, rule in conditions.items():
if key(expr):
return rule(expr)
return multiplexer_rl
def alternatives(*rules):
"""Strategy that makes an AlternativeRule out of multiple possible results."""
def _alternatives(integral):
alts = []
count = 0
debug("List of Alternative Rules")
for rule in rules:
count = count + 1
debug("Rule {}: {}".format(count, rule))
result = rule(integral)
if (result and not isinstance(result, DontKnowRule) and
result != integral and result not in alts):
alts.append(result)
if len(alts) == 1:
return alts[0]
elif alts:
doable = [rule for rule in alts if not contains_dont_know(rule)]
if doable:
return AlternativeRule(doable, *integral)
else:
return AlternativeRule(alts, *integral)
return _alternatives
def constant_rule(integral):
return ConstantRule(integral.integrand, *integral)
def power_rule(integral):
integrand, symbol = integral
base, exp = integrand.as_base_exp()
if symbol not in exp.free_symbols and isinstance(base, sympy.Symbol):
if sympy.simplify(exp + 1) == 0:
return ReciprocalRule(base, integrand, symbol)
return PowerRule(base, exp, integrand, symbol)
elif symbol not in base.free_symbols and isinstance(exp, sympy.Symbol):
rule = ExpRule(base, exp, integrand, symbol)
if fuzzy_not(sympy.log(base).is_zero):
return rule
elif sympy.log(base).is_zero:
return ConstantRule(1, 1, symbol)
return PiecewiseRule([
(rule, sympy.Ne(sympy.log(base), 0)),
(ConstantRule(1, 1, symbol), True)
], integrand, symbol)
def exp_rule(integral):
integrand, symbol = integral
if isinstance(integrand.args[0], sympy.Symbol):
return ExpRule(sympy.E, integrand.args[0], integrand, symbol)
def orthogonal_poly_rule(integral):
orthogonal_poly_classes = {
sympy.jacobi: JacobiRule,
sympy.gegenbauer: GegenbauerRule,
sympy.chebyshevt: ChebyshevTRule,
sympy.chebyshevu: ChebyshevURule,
sympy.legendre: LegendreRule,
sympy.hermite: HermiteRule,
sympy.laguerre: LaguerreRule,
sympy.assoc_laguerre: AssocLaguerreRule
}
orthogonal_poly_var_index = {
sympy.jacobi: 3,
sympy.gegenbauer: 2,
sympy.assoc_laguerre: 2
}
integrand, symbol = integral
for klass in orthogonal_poly_classes:
if isinstance(integrand, klass):
var_index = orthogonal_poly_var_index.get(klass, 1)
if (integrand.args[var_index] is symbol and not
any(v.has(symbol) for v in integrand.args[:var_index])):
args = integrand.args[:var_index] + (integrand, symbol)
return orthogonal_poly_classes[klass](*args)
def special_function_rule(integral):
integrand, symbol = integral
a = sympy.Wild('a', exclude=[symbol], properties=[lambda x: not x.is_zero])
b = sympy.Wild('b', exclude=[symbol])
c = sympy.Wild('c', exclude=[symbol])
d = sympy.Wild('d', exclude=[symbol], properties=[lambda x: not x.is_zero])
e = sympy.Wild('e', exclude=[symbol], properties=[
lambda x: not (x.is_nonnegative and x.is_integer)])
wilds = (a, b, c, d, e)
# patterns consist of a SymPy class, a wildcard expr, an optional
# condition coded as a lambda (when Wild properties are not enough),
# followed by an applicable rule
patterns = (
(sympy.Mul, sympy.exp(a*symbol + b)/symbol, None, EiRule),
(sympy.Mul, sympy.cos(a*symbol + b)/symbol, None, CiRule),
(sympy.Mul, sympy.cosh(a*symbol + b)/symbol, None, ChiRule),
(sympy.Mul, sympy.sin(a*symbol + b)/symbol, None, SiRule),
(sympy.Mul, sympy.sinh(a*symbol + b)/symbol, None, ShiRule),
(sympy.Pow, 1/sympy.log(a*symbol + b), None, LiRule),
(sympy.exp, sympy.exp(a*symbol**2 + b*symbol + c), None, ErfRule),
(sympy.sin, sympy.sin(a*symbol**2 + b*symbol + c), None, FresnelSRule),
(sympy.cos, sympy.cos(a*symbol**2 + b*symbol + c), None, FresnelCRule),
(sympy.Mul, symbol**e*sympy.exp(a*symbol), None, UpperGammaRule),
(sympy.Mul, sympy.polylog(b, a*symbol)/symbol, None, PolylogRule),
(sympy.Pow, 1/sympy.sqrt(a - d*sympy.sin(symbol)**2),
lambda a, d: a != d, EllipticFRule),
(sympy.Pow, sympy.sqrt(a - d*sympy.sin(symbol)**2),
lambda a, d: a != d, EllipticERule),
)
for p in patterns:
if isinstance(integrand, p[0]):
match = integrand.match(p[1])
if match:
wild_vals = tuple(match.get(w) for w in wilds
if match.get(w) is not None)
if p[2] is None or p[2](*wild_vals):
args = wild_vals + (integrand, symbol)
return p[3](*args)
def inverse_trig_rule(integral):
integrand, symbol = integral
base, exp = integrand.as_base_exp()
a = sympy.Wild('a', exclude=[symbol])
b = sympy.Wild('b', exclude=[symbol])
match = base.match(a + b*symbol**2)
if not match:
return
def negative(x):
return x.is_negative or x.could_extract_minus_sign()
def ArcsinhRule(integrand, symbol):
return InverseHyperbolicRule(sympy.asinh, integrand, symbol)
def ArccoshRule(integrand, symbol):
return InverseHyperbolicRule(sympy.acosh, integrand, symbol)
def make_inverse_trig(RuleClass, base_exp, a, sign_a, b, sign_b):
u_var = sympy.Dummy("u")
current_base = base
current_symbol = symbol
constant = u_func = u_constant = substep = None
factored = integrand
if a != 1:
constant = a**base_exp
current_base = sign_a + sign_b * (b/a) * current_symbol**2
factored = current_base ** base_exp
if (b/a) != 1:
u_func = sympy.sqrt(b/a) * symbol
u_constant = sympy.sqrt(a/b)
current_symbol = u_var
current_base = sign_a + sign_b * current_symbol**2
substep = RuleClass(current_base ** base_exp, current_symbol)
if u_func is not None:
if u_constant != 1 and substep is not None:
substep = ConstantTimesRule(
u_constant, current_base ** base_exp, substep,
u_constant * current_base ** base_exp, symbol)
substep = URule(u_var, u_func, u_constant, substep, factored, symbol)
if constant is not None and substep is not None:
substep = ConstantTimesRule(constant, factored, substep, integrand, symbol)
return substep
a, b = [match.get(i, ZERO) for i in (a, b)]
# list of (rule, base_exp, a, sign_a, b, sign_b, condition)
possibilities = []
if sympy.simplify(2*exp + 1) == 0:
possibilities.append((ArcsinRule, exp, a, 1, -b, -1, sympy.And(a > 0, b < 0)))
possibilities.append((ArcsinhRule, exp, a, 1, b, 1, sympy.And(a > 0, b > 0)))
possibilities.append((ArccoshRule, exp, -a, -1, b, 1, sympy.And(a < 0, b > 0)))
possibilities = [p for p in possibilities if p[-1] is not sympy.false]
if a.is_number and b.is_number:
possibility = [p for p in possibilities if p[-1] is sympy.true]
if len(possibility) == 1:
return make_inverse_trig(*possibility[0][:-1])
elif possibilities:
return PiecewiseRule(
[(make_inverse_trig(*p[:-1]), p[-1]) for p in possibilities],
integrand, symbol)
def add_rule(integral):
integrand, symbol = integral
results = [integral_steps(g, symbol)
for g in integrand.as_ordered_terms()]
return None if None in results else AddRule(results, integrand, symbol)
def mul_rule(integral):
integrand, symbol = integral
# Constant times function case
coeff, f = integrand.as_independent(symbol)
next_step = integral_steps(f, symbol)
if coeff != 1 and next_step is not None:
return ConstantTimesRule(
coeff, f,
next_step,
integrand, symbol)
def _parts_rule(integrand, symbol):
# LIATE rule:
# log, inverse trig, algebraic, trigonometric, exponential
def pull_out_algebraic(integrand):
integrand = integrand.cancel().together()
# iterating over Piecewise args would not work here
algebraic = ([] if isinstance(integrand, sympy.Piecewise)
else [arg for arg in integrand.args if arg.is_algebraic_expr(symbol)])
if algebraic:
u = sympy.Mul(*algebraic)
dv = (integrand / u).cancel()
return u, dv
def pull_out_u(*functions):
def pull_out_u_rl(integrand):
if any([integrand.has(f) for f in functions]):
args = [arg for arg in integrand.args
if any(isinstance(arg, cls) for cls in functions)]
if args:
u = reduce(lambda a,b: a*b, args)
dv = integrand / u
return u, dv
return pull_out_u_rl
liate_rules = [pull_out_u(sympy.log), pull_out_u(*inverse_trig_functions),
pull_out_algebraic, pull_out_u(sympy.sin, sympy.cos),
pull_out_u(sympy.exp)]
dummy = sympy.Dummy("temporary")
# we can integrate log(x) and atan(x) by setting dv = 1
if isinstance(integrand, (sympy.log, *inverse_trig_functions)):
integrand = dummy * integrand
for index, rule in enumerate(liate_rules):
result = rule(integrand)
if result:
u, dv = result
# Don't pick u to be a constant if possible
if symbol not in u.free_symbols and not u.has(dummy):
return
u = u.subs(dummy, 1)
dv = dv.subs(dummy, 1)
# Don't pick a non-polynomial algebraic to be differentiated
if rule == pull_out_algebraic and not u.is_polynomial(symbol):
return
# Don't trade one logarithm for another
if isinstance(u, sympy.log):
rec_dv = 1/dv
if (rec_dv.is_polynomial(symbol) and
degree(rec_dv, symbol) == 1):
return
# Can integrate a polynomial times OrthogonalPolynomial
if rule == pull_out_algebraic and isinstance(dv, OrthogonalPolynomial):
v_step = integral_steps(dv, symbol)
if contains_dont_know(v_step):
return
else:
du = u.diff(symbol)
v = _manualintegrate(v_step)
return u, dv, v, du, v_step
# make sure dv is amenable to integration
accept = False
if index < 2: # log and inverse trig are usually worth trying
accept = True
elif (rule == pull_out_algebraic and dv.args and
all(isinstance(a, (sympy.sin, sympy.cos, sympy.exp))
for a in dv.args)):
accept = True
else:
for rule in liate_rules[index + 1:]:
r = rule(integrand)
if r and r[0].subs(dummy, 1).equals(dv):
accept = True
break
if accept:
du = u.diff(symbol)
v_step = integral_steps(sympy.simplify(dv), symbol)
if not contains_dont_know(v_step):
v = _manualintegrate(v_step)
return u, dv, v, du, v_step
def parts_rule(integral):
integrand, symbol = integral
constant, integrand = integrand.as_coeff_Mul()
result = _parts_rule(integrand, symbol)
steps = []
if result:
u, dv, v, du, v_step = result
debug("u : {}, dv : {}, v : {}, du : {}, v_step: {}".format(u, dv, v, du, v_step))
steps.append(result)
if isinstance(v, sympy.Integral):
return
# Set a limit on the number of times u can be used
if isinstance(u, (sympy.sin, sympy.cos, sympy.exp, sympy.sinh, sympy.cosh)):
cachekey = u.xreplace({symbol: _cache_dummy})
if _parts_u_cache[cachekey] > 2:
return
_parts_u_cache[cachekey] += 1
# Try cyclic integration by parts a few times
for _ in range(4):
debug("Cyclic integration {} with v: {}, du: {}, integrand: {}".format(_, v, du, integrand))
coefficient = ((v * du) / integrand).cancel()
if coefficient == 1:
break
if symbol not in coefficient.free_symbols:
rule = CyclicPartsRule(
[PartsRule(u, dv, v_step, None, None, None)
for (u, dv, v, du, v_step) in steps],
(-1) ** len(steps) * coefficient,
integrand, symbol
)
if (constant != 1) and rule:
rule = ConstantTimesRule(constant, integrand, rule,
constant * integrand, symbol)
return rule
# _parts_rule is sensitive to constants, factor it out
next_constant, next_integrand = (v * du).as_coeff_Mul()
result = _parts_rule(next_integrand, symbol)
if result:
u, dv, v, du, v_step = result
u *= next_constant
du *= next_constant
steps.append((u, dv, v, du, v_step))
else:
break
def make_second_step(steps, integrand):
if steps:
u, dv, v, du, v_step = steps[0]
return PartsRule(u, dv, v_step,
make_second_step(steps[1:], v * du),
integrand, symbol)
else:
steps = integral_steps(integrand, symbol)
if steps:
return steps
else:
return DontKnowRule(integrand, symbol)
if steps:
u, dv, v, du, v_step = steps[0]
rule = PartsRule(u, dv, v_step,
make_second_step(steps[1:], v * du),
integrand, symbol)
if (constant != 1) and rule:
rule = ConstantTimesRule(constant, integrand, rule,
constant * integrand, symbol)
return rule
def trig_rule(integral):
integrand, symbol = integral
if isinstance(integrand, sympy.sin) or isinstance(integrand, sympy.cos):
arg = integrand.args[0]
if not isinstance(arg, sympy.Symbol):
return # perhaps a substitution can deal with it
if isinstance(integrand, sympy.sin):
func = 'sin'
else:
func = 'cos'
return TrigRule(func, arg, integrand, symbol)
if integrand == sympy.sec(symbol)**2:
return TrigRule('sec**2', symbol, integrand, symbol)
elif integrand == sympy.csc(symbol)**2:
return TrigRule('csc**2', symbol, integrand, symbol)
if isinstance(integrand, sympy.tan):
rewritten = sympy.sin(*integrand.args) / sympy.cos(*integrand.args)
elif isinstance(integrand, sympy.cot):
rewritten = sympy.cos(*integrand.args) / sympy.sin(*integrand.args)
elif isinstance(integrand, sympy.sec):
arg = integrand.args[0]
rewritten = ((sympy.sec(arg)**2 + sympy.tan(arg) * sympy.sec(arg)) /
(sympy.sec(arg) + sympy.tan(arg)))
elif isinstance(integrand, sympy.csc):
arg = integrand.args[0]
rewritten = ((sympy.csc(arg)**2 + sympy.cot(arg) * sympy.csc(arg)) /
(sympy.csc(arg) + sympy.cot(arg)))
else:
return
return RewriteRule(
rewritten,
integral_steps(rewritten, symbol),
integrand, symbol
)
def trig_product_rule(integral):
integrand, symbol = integral
sectan = sympy.sec(symbol) * sympy.tan(symbol)
q = integrand / sectan
if symbol not in q.free_symbols:
rule = TrigRule('sec*tan', symbol, sectan, symbol)
if q != 1 and rule:
rule = ConstantTimesRule(q, sectan, rule, integrand, symbol)
return rule
csccot = -sympy.csc(symbol) * sympy.cot(symbol)
q = integrand / csccot
if symbol not in q.free_symbols:
rule = TrigRule('csc*cot', symbol, csccot, symbol)
if q != 1 and rule:
rule = ConstantTimesRule(q, csccot, rule, integrand, symbol)
return rule
def quadratic_denom_rule(integral):
integrand, symbol = integral
a = sympy.Wild('a', exclude=[symbol])
b = sympy.Wild('b', exclude=[symbol])
c = sympy.Wild('c', exclude=[symbol])
match = integrand.match(a / (b * symbol ** 2 + c))
if match:
a, b, c = match[a], match[b], match[c]
if b.is_extended_real and c.is_extended_real:
return PiecewiseRule([(ArctanRule(a, b, c, integrand, symbol), sympy.Gt(c / b, 0)),
(ArccothRule(a, b, c, integrand, symbol), sympy.And(sympy.Gt(symbol ** 2, -c / b), sympy.Lt(c / b, 0))),
(ArctanhRule(a, b, c, integrand, symbol), sympy.And(sympy.Lt(symbol ** 2, -c / b), sympy.Lt(c / b, 0))),
], integrand, symbol)
else:
return ArctanRule(a, b, c, integrand, symbol)
d = sympy.Wild('d', exclude=[symbol])
match2 = integrand.match(a / (b * symbol ** 2 + c * symbol + d))
if match2:
b, c = match2[b], match2[c]
if b.is_zero:
return
u = sympy.Dummy('u')
u_func = symbol + c/(2*b)
integrand2 = integrand.subs(symbol, u - c / (2*b))
next_step = integral_steps(integrand2, u)
if next_step:
return URule(u, u_func, None, next_step, integrand2, symbol)
else:
return
e = sympy.Wild('e', exclude=[symbol])
match3 = integrand.match((a* symbol + b) / (c * symbol ** 2 + d * symbol + e))
if match3:
a, b, c, d, e = match3[a], match3[b], match3[c], match3[d], match3[e]
if c.is_zero:
return
denominator = c * symbol**2 + d * symbol + e
const = a/(2*c)
numer1 = (2*c*symbol+d)
numer2 = - const*d + b
u = sympy.Dummy('u')
step1 = URule(u,
denominator,
const,
integral_steps(u**(-1), u),
integrand,
symbol)
if const != 1:
step1 = ConstantTimesRule(const,
numer1/denominator,
step1,
const*numer1/denominator,
symbol)
if numer2.is_zero:
return step1
step2 = integral_steps(numer2/denominator, symbol)
substeps = AddRule([step1, step2], integrand, symbol)
rewriten = const*numer1/denominator+numer2/denominator
return RewriteRule(rewriten, substeps, integrand, symbol)
return
def root_mul_rule(integral):
integrand, symbol = integral
a = sympy.Wild('a', exclude=[symbol])
b = sympy.Wild('b', exclude=[symbol])
c = sympy.Wild('c')
match = integrand.match(sympy.sqrt(a * symbol + b) * c)
if not match:
return
a, b, c = match[a], match[b], match[c]
d = sympy.Wild('d', exclude=[symbol])
e = sympy.Wild('e', exclude=[symbol])
f = sympy.Wild('f')
recursion_test = c.match(sympy.sqrt(d * symbol + e) * f)
if recursion_test:
return
u = sympy.Dummy('u')
u_func = sympy.sqrt(a * symbol + b)
integrand = integrand.subs(u_func, u)
integrand = integrand.subs(symbol, (u**2 - b) / a)
integrand = integrand * 2 * u / a
next_step = integral_steps(integrand, u)
if next_step:
return URule(u, u_func, None, next_step, integrand, symbol)
@sympy.cacheit
def make_wilds(symbol):
a = sympy.Wild('a', exclude=[symbol])
b = sympy.Wild('b', exclude=[symbol])
m = sympy.Wild('m', exclude=[symbol], properties=[lambda n: isinstance(n, sympy.Integer)])
n = sympy.Wild('n', exclude=[symbol], properties=[lambda n: isinstance(n, sympy.Integer)])
return a, b, m, n
@sympy.cacheit
def sincos_pattern(symbol):
a, b, m, n = make_wilds(symbol)
pattern = sympy.sin(a*symbol)**m * sympy.cos(b*symbol)**n
return pattern, a, b, m, n
@sympy.cacheit
def tansec_pattern(symbol):
a, b, m, n = make_wilds(symbol)
pattern = sympy.tan(a*symbol)**m * sympy.sec(b*symbol)**n
return pattern, a, b, m, n
@sympy.cacheit
def cotcsc_pattern(symbol):
a, b, m, n = make_wilds(symbol)
pattern = sympy.cot(a*symbol)**m * sympy.csc(b*symbol)**n
return pattern, a, b, m, n
@sympy.cacheit
def heaviside_pattern(symbol):
m = sympy.Wild('m', exclude=[symbol])
b = sympy.Wild('b', exclude=[symbol])
g = sympy.Wild('g')
pattern = sympy.Heaviside(m*symbol + b) * g
return pattern, m, b, g
def uncurry(func):
def uncurry_rl(args):
return func(*args)
return uncurry_rl
def trig_rewriter(rewrite):
def trig_rewriter_rl(args):
a, b, m, n, integrand, symbol = args
rewritten = rewrite(a, b, m, n, integrand, symbol)
if rewritten != integrand:
return RewriteRule(
rewritten,
integral_steps(rewritten, symbol),
integrand, symbol)
return trig_rewriter_rl
sincos_botheven_condition = uncurry(
lambda a, b, m, n, i, s: m.is_even and n.is_even and
m.is_nonnegative and n.is_nonnegative)
sincos_botheven = trig_rewriter(
lambda a, b, m, n, i, symbol: ( (((1 - sympy.cos(2*a*symbol)) / 2) ** (m / 2)) *
(((1 + sympy.cos(2*b*symbol)) / 2) ** (n / 2)) ))
sincos_sinodd_condition = uncurry(lambda a, b, m, n, i, s: m.is_odd and m >= 3)
sincos_sinodd = trig_rewriter(
lambda a, b, m, n, i, symbol: ( (1 - sympy.cos(a*symbol)**2)**((m - 1) / 2) *
sympy.sin(a*symbol) *
sympy.cos(b*symbol) ** n))
sincos_cosodd_condition = uncurry(lambda a, b, m, n, i, s: n.is_odd and n >= 3)
sincos_cosodd = trig_rewriter(
lambda a, b, m, n, i, symbol: ( (1 - sympy.sin(b*symbol)**2)**((n - 1) / 2) *
sympy.cos(b*symbol) *
sympy.sin(a*symbol) ** m))
tansec_seceven_condition = uncurry(lambda a, b, m, n, i, s: n.is_even and n >= 4)
tansec_seceven = trig_rewriter(
lambda a, b, m, n, i, symbol: ( (1 + sympy.tan(b*symbol)**2) ** (n/2 - 1) *
sympy.sec(b*symbol)**2 *
sympy.tan(a*symbol) ** m ))
tansec_tanodd_condition = uncurry(lambda a, b, m, n, i, s: m.is_odd)
tansec_tanodd = trig_rewriter(
lambda a, b, m, n, i, symbol: ( (sympy.sec(a*symbol)**2 - 1) ** ((m - 1) / 2) *
sympy.tan(a*symbol) *
sympy.sec(b*symbol) ** n ))
tan_tansquared_condition = uncurry(lambda a, b, m, n, i, s: m == 2 and n == 0)
tan_tansquared = trig_rewriter(
lambda a, b, m, n, i, symbol: ( sympy.sec(a*symbol)**2 - 1))
cotcsc_csceven_condition = uncurry(lambda a, b, m, n, i, s: n.is_even and n >= 4)
cotcsc_csceven = trig_rewriter(
lambda a, b, m, n, i, symbol: ( (1 + sympy.cot(b*symbol)**2) ** (n/2 - 1) *
sympy.csc(b*symbol)**2 *
sympy.cot(a*symbol) ** m ))
cotcsc_cotodd_condition = uncurry(lambda a, b, m, n, i, s: m.is_odd)
cotcsc_cotodd = trig_rewriter(
lambda a, b, m, n, i, symbol: ( (sympy.csc(a*symbol)**2 - 1) ** ((m - 1) / 2) *
sympy.cot(a*symbol) *
sympy.csc(b*symbol) ** n ))
def trig_sincos_rule(integral):
integrand, symbol = integral
if any(integrand.has(f) for f in (sympy.sin, sympy.cos)):
pattern, a, b, m, n = sincos_pattern(symbol)
match = integrand.match(pattern)
if not match:
return
return multiplexer({
sincos_botheven_condition: sincos_botheven,
sincos_sinodd_condition: sincos_sinodd,
sincos_cosodd_condition: sincos_cosodd
})(tuple(
[match.get(i, ZERO) for i in (a, b, m, n)] +
[integrand, symbol]))
def trig_tansec_rule(integral):
integrand, symbol = integral
integrand = integrand.subs({
1 / sympy.cos(symbol): sympy.sec(symbol)
})
if any(integrand.has(f) for f in (sympy.tan, sympy.sec)):
pattern, a, b, m, n = tansec_pattern(symbol)
match = integrand.match(pattern)
if not match:
return
return multiplexer({
tansec_tanodd_condition: tansec_tanodd,
tansec_seceven_condition: tansec_seceven,
tan_tansquared_condition: tan_tansquared
})(tuple(
[match.get(i, ZERO) for i in (a, b, m, n)] +
[integrand, symbol]))
def trig_cotcsc_rule(integral):
integrand, symbol = integral
integrand = integrand.subs({
1 / sympy.sin(symbol): sympy.csc(symbol),
1 / sympy.tan(symbol): sympy.cot(symbol),
sympy.cos(symbol) / sympy.tan(symbol): sympy.cot(symbol)
})
if any(integrand.has(f) for f in (sympy.cot, sympy.csc)):
pattern, a, b, m, n = cotcsc_pattern(symbol)
match = integrand.match(pattern)
if not match:
return
return multiplexer({
cotcsc_cotodd_condition: cotcsc_cotodd,
cotcsc_csceven_condition: cotcsc_csceven
})(tuple(
[match.get(i, ZERO) for i in (a, b, m, n)] +
[integrand, symbol]))
def trig_sindouble_rule(integral):
integrand, symbol = integral
a = sympy.Wild('a', exclude=[sympy.sin(2*symbol)])
match = integrand.match(sympy.sin(2*symbol)*a)
if match:
sin_double = 2*sympy.sin(symbol)*sympy.cos(symbol)/sympy.sin(2*symbol)
return integral_steps(integrand * sin_double, symbol)
def trig_powers_products_rule(integral):
return do_one(null_safe(trig_sincos_rule),
null_safe(trig_tansec_rule),
null_safe(trig_cotcsc_rule),
null_safe(trig_sindouble_rule))(integral)
def trig_substitution_rule(integral):
integrand, symbol = integral
A = sympy.Wild('a', exclude=[0, symbol])
B = sympy.Wild('b', exclude=[0, symbol])
theta = sympy.Dummy("theta")
target_pattern = A + B*symbol**2
matches = integrand.find(target_pattern)
for expr in matches:
match = expr.match(target_pattern)
a = match.get(A, ZERO)
b = match.get(B, ZERO)
a_positive = ((a.is_number and a > 0) or a.is_positive)
b_positive = ((b.is_number and b > 0) or b.is_positive)
a_negative = ((a.is_number and a < 0) or a.is_negative)
b_negative = ((b.is_number and b < 0) or b.is_negative)
x_func = None
if a_positive and b_positive:
# a**2 + b*x**2. Assume sec(theta) > 0, -pi/2 < theta < pi/2
x_func = (sympy.sqrt(a)/sympy.sqrt(b)) * sympy.tan(theta)
# Do not restrict the domain: tan(theta) takes on any real
# value on the interval -pi/2 < theta < pi/2 so x takes on
# any value
restriction = True
elif a_positive and b_negative:
# a**2 - b*x**2. Assume cos(theta) > 0, -pi/2 < theta < pi/2
constant = sympy.sqrt(a)/sympy.sqrt(-b)
x_func = constant * sympy.sin(theta)
restriction = sympy.And(symbol > -constant, symbol < constant)
elif a_negative and b_positive:
# b*x**2 - a**2. Assume sin(theta) > 0, 0 < theta < pi
constant = sympy.sqrt(-a)/sympy.sqrt(b)
x_func = constant * sympy.sec(theta)
restriction = sympy.And(symbol > -constant, symbol < constant)
if x_func:
# Manually simplify sqrt(trig(theta)**2) to trig(theta)
# Valid due to assumed domain restriction
substitutions = {}
for f in [sympy.sin, sympy.cos, sympy.tan,
sympy.sec, sympy.csc, sympy.cot]:
substitutions[sympy.sqrt(f(theta)**2)] = f(theta)
substitutions[sympy.sqrt(f(theta)**(-2))] = 1/f(theta)
replaced = integrand.subs(symbol, x_func).trigsimp()
replaced = manual_subs(replaced, substitutions)
if not replaced.has(symbol):
replaced *= manual_diff(x_func, theta)
replaced = replaced.trigsimp()
secants = replaced.find(1/sympy.cos(theta))
if secants:
replaced = replaced.xreplace({
1/sympy.cos(theta): sympy.sec(theta)
})
substep = integral_steps(replaced, theta)
if not contains_dont_know(substep):
return TrigSubstitutionRule(
theta, x_func, replaced, substep, restriction,
integrand, symbol)
def heaviside_rule(integral):
integrand, symbol = integral
pattern, m, b, g = heaviside_pattern(symbol)
match = integrand.match(pattern)
if match and 0 != match[g]:
# f = Heaviside(m*x + b)*g
v_step = integral_steps(match[g], symbol)
result = _manualintegrate(v_step)
m, b = match[m], match[b]
return HeavisideRule(m*symbol + b, -b/m, result, integrand, symbol)
def substitution_rule(integral):
integrand, symbol = integral
u_var = sympy.Dummy("u")
substitutions = find_substitutions(integrand, symbol, u_var)
count = 0
if substitutions:
debug("List of Substitution Rules")
ways = []
for u_func, c, substituted in substitutions:
subrule = integral_steps(substituted, u_var)
count = count + 1
debug("Rule {}: {}".format(count, subrule))
if contains_dont_know(subrule):
continue
if sympy.simplify(c - 1) != 0:
_, denom = c.as_numer_denom()
if subrule:
subrule = ConstantTimesRule(c, substituted, subrule, substituted, u_var)
if denom.free_symbols:
piecewise = []
could_be_zero = []
if isinstance(denom, sympy.Mul):
could_be_zero = denom.args
else:
could_be_zero.append(denom)
for expr in could_be_zero:
if not fuzzy_not(expr.is_zero):
substep = integral_steps(manual_subs(integrand, expr, 0), symbol)
if substep:
piecewise.append((
substep,
sympy.Eq(expr, 0)
))
piecewise.append((subrule, True))
subrule = PiecewiseRule(piecewise, substituted, symbol)
ways.append(URule(u_var, u_func, c,
subrule,
integrand, symbol))
if len(ways) > 1:
return AlternativeRule(ways, integrand, symbol)
elif ways:
return ways[0]
elif integrand.has(sympy.exp):
u_func = sympy.exp(symbol)
c = 1
substituted = integrand / u_func.diff(symbol)
substituted = substituted.subs(u_func, u_var)
if symbol not in substituted.free_symbols:
return URule(u_var, u_func, c,
integral_steps(substituted, u_var),
integrand, symbol)
partial_fractions_rule = rewriter(
lambda integrand, symbol: integrand.is_rational_function(),
lambda integrand, symbol: integrand.apart(symbol))
cancel_rule = rewriter(
# lambda integrand, symbol: integrand.is_algebraic_expr(),
# lambda integrand, symbol: isinstance(integrand, sympy.Mul),
lambda integrand, symbol: True,
lambda integrand, symbol: integrand.cancel())
distribute_expand_rule = rewriter(
lambda integrand, symbol: (
all(arg.is_Pow or arg.is_polynomial(symbol) for arg in integrand.args)
or isinstance(integrand, sympy.Pow)
or isinstance(integrand, sympy.Mul)),
lambda integrand, symbol: integrand.expand())
trig_expand_rule = rewriter(
# If there are trig functions with different arguments, expand them
lambda integrand, symbol: (
len({a.args[0] for a in integrand.atoms(TrigonometricFunction)}) > 1),
lambda integrand, symbol: integrand.expand(trig=True))
def derivative_rule(integral):
integrand = integral[0]
diff_variables = integrand.variables
undifferentiated_function = integrand.expr
integrand_variables = undifferentiated_function.free_symbols
if integral.symbol in integrand_variables:
if integral.symbol in diff_variables:
return DerivativeRule(*integral)
else:
return DontKnowRule(integrand, integral.symbol)
else:
return ConstantRule(integral.integrand, *integral)
def rewrites_rule(integral):
integrand, symbol = integral
if integrand.match(1/sympy.cos(symbol)):
rewritten = integrand.subs(1/sympy.cos(symbol), sympy.sec(symbol))
return RewriteRule(rewritten, integral_steps(rewritten, symbol), integrand, symbol)
def fallback_rule(integral):
return DontKnowRule(*integral)
# Cache is used to break cyclic integrals.
# Need to use the same dummy variable in cached expressions for them to match.
# Also record "u" of integration by parts, to avoid infinite repetition.
_integral_cache = {} # type: tDict[Expr, Optional[Expr]]
_parts_u_cache = defaultdict(int) # type: tDict[Expr, int]
_cache_dummy = sympy.Dummy("z")
def integral_steps(integrand, symbol, **options):
"""Returns the steps needed to compute an integral.
Explanation
===========
This function attempts to mirror what a student would do by hand as
closely as possible.
SymPy Gamma uses this to provide a step-by-step explanation of an
integral. The code it uses to format the results of this function can be
found at
https://github.com/sympy/sympy_gamma/blob/master/app/logic/intsteps.py.
Examples
========
>>> from sympy import exp, sin
>>> from sympy.integrals.manualintegrate import integral_steps
>>> from sympy.abc import x
>>> print(repr(integral_steps(exp(x) / (1 + exp(2 * x)), x))) \
# doctest: +NORMALIZE_WHITESPACE
URule(u_var=_u, u_func=exp(x), constant=1,
substep=PiecewiseRule(subfunctions=[(ArctanRule(a=1, b=1, c=1, context=1/(_u**2 + 1), symbol=_u), True),
(ArccothRule(a=1, b=1, c=1, context=1/(_u**2 + 1), symbol=_u), False),
(ArctanhRule(a=1, b=1, c=1, context=1/(_u**2 + 1), symbol=_u), False)],
context=1/(_u**2 + 1), symbol=_u), context=exp(x)/(exp(2*x) + 1), symbol=x)
>>> print(repr(integral_steps(sin(x), x))) \
# doctest: +NORMALIZE_WHITESPACE
TrigRule(func='sin', arg=x, context=sin(x), symbol=x)
>>> print(repr(integral_steps((x**2 + 3)**2 , x))) \
# doctest: +NORMALIZE_WHITESPACE
RewriteRule(rewritten=x**4 + 6*x**2 + 9,
substep=AddRule(substeps=[PowerRule(base=x, exp=4, context=x**4, symbol=x),
ConstantTimesRule(constant=6, other=x**2,
substep=PowerRule(base=x, exp=2, context=x**2, symbol=x),
context=6*x**2, symbol=x),
ConstantRule(constant=9, context=9, symbol=x)],
context=x**4 + 6*x**2 + 9, symbol=x), context=(x**2 + 3)**2, symbol=x)
Returns
=======
rule : namedtuple
The first step; most rules have substeps that must also be
considered. These substeps can be evaluated using ``manualintegrate``
to obtain a result.
"""
cachekey = integrand.xreplace({symbol: _cache_dummy})
if cachekey in _integral_cache:
if _integral_cache[cachekey] is None:
# Stop this attempt, because it leads around in a loop
return DontKnowRule(integrand, symbol)
else:
# TODO: This is for future development, as currently
# _integral_cache gets no values other than None
return (_integral_cache[cachekey].xreplace(_cache_dummy, symbol),
symbol)
else:
_integral_cache[cachekey] = None
integral = IntegralInfo(integrand, symbol)
def key(integral):
integrand = integral.integrand
if isinstance(integrand, TrigonometricFunction):
return TrigonometricFunction
elif isinstance(integrand, sympy.Derivative):
return sympy.Derivative
elif symbol not in integrand.free_symbols:
return sympy.Number
else:
for cls in (sympy.Pow, sympy.Symbol, sympy.exp, sympy.log,
sympy.Add, sympy.Mul, *inverse_trig_functions,
sympy.Heaviside, OrthogonalPolynomial):
if isinstance(integrand, cls):
return cls
def integral_is_subclass(*klasses):
def _integral_is_subclass(integral):
k = key(integral)
return k and issubclass(k, klasses)
return _integral_is_subclass
result = do_one(
null_safe(special_function_rule),
null_safe(switch(key, {
sympy.Pow: do_one(null_safe(power_rule), null_safe(inverse_trig_rule), \
null_safe(quadratic_denom_rule)),
sympy.Symbol: power_rule,
sympy.exp: exp_rule,
sympy.Add: add_rule,
sympy.Mul: do_one(null_safe(mul_rule), null_safe(trig_product_rule), \
null_safe(heaviside_rule), null_safe(quadratic_denom_rule), \
null_safe(root_mul_rule)),
sympy.Derivative: derivative_rule,
TrigonometricFunction: trig_rule,
sympy.Heaviside: heaviside_rule,
OrthogonalPolynomial: orthogonal_poly_rule,
sympy.Number: constant_rule
})),
do_one(
null_safe(trig_rule),
null_safe(alternatives(
rewrites_rule,
substitution_rule,
condition(
integral_is_subclass(sympy.Mul, sympy.Pow),
partial_fractions_rule),
condition(
integral_is_subclass(sympy.Mul, sympy.Pow),
cancel_rule),
condition(
integral_is_subclass(sympy.Mul, sympy.log,
*inverse_trig_functions),
parts_rule),
condition(
integral_is_subclass(sympy.Mul, sympy.Pow),
distribute_expand_rule),
trig_powers_products_rule,
trig_expand_rule
)),
null_safe(trig_substitution_rule)
),
fallback_rule)(integral)
del _integral_cache[cachekey]
return result
@evaluates(ConstantRule)
def eval_constant(constant, integrand, symbol):
return constant * symbol
@evaluates(ConstantTimesRule)
def eval_constanttimes(constant, other, substep, integrand, symbol):
return constant * _manualintegrate(substep)
@evaluates(PowerRule)
def eval_power(base, exp, integrand, symbol):
return sympy.Piecewise(
((base**(exp + 1))/(exp + 1), sympy.Ne(exp, -1)),
(sympy.log(base), True),
)
@evaluates(ExpRule)
def eval_exp(base, exp, integrand, symbol):
return integrand / sympy.ln(base)
@evaluates(AddRule)
def eval_add(substeps, integrand, symbol):
return sum(map(_manualintegrate, substeps))
@evaluates(URule)
def eval_u(u_var, u_func, constant, substep, integrand, symbol):
result = _manualintegrate(substep)
if u_func.is_Pow and u_func.exp == -1:
# avoid needless -log(1/x) from substitution
result = result.subs(sympy.log(u_var), -sympy.log(u_func.base))
return result.subs(u_var, u_func)
@evaluates(PartsRule)
def eval_parts(u, dv, v_step, second_step, integrand, symbol):
v = _manualintegrate(v_step)
return u * v - _manualintegrate(second_step)
@evaluates(CyclicPartsRule)
def eval_cyclicparts(parts_rules, coefficient, integrand, symbol):
coefficient = 1 - coefficient
result = []
sign = 1
for rule in parts_rules:
result.append(sign * rule.u * _manualintegrate(rule.v_step))
sign *= -1
return sympy.Add(*result) / coefficient
@evaluates(TrigRule)
def eval_trig(func, arg, integrand, symbol):
if func == 'sin':
return -sympy.cos(arg)
elif func == 'cos':
return sympy.sin(arg)
elif func == 'sec*tan':
return sympy.sec(arg)
elif func == 'csc*cot':
return sympy.csc(arg)
elif func == 'sec**2':
return sympy.tan(arg)
elif func == 'csc**2':
return -sympy.cot(arg)
@evaluates(ArctanRule)
def eval_arctan(a, b, c, integrand, symbol):
return a / b * 1 / sympy.sqrt(c / b) * sympy.atan(symbol / sympy.sqrt(c / b))
@evaluates(ArccothRule)
def eval_arccoth(a, b, c, integrand, symbol):
return - a / b * 1 / sympy.sqrt(-c / b) * sympy.acoth(symbol / sympy.sqrt(-c / b))
@evaluates(ArctanhRule)
def eval_arctanh(a, b, c, integrand, symbol):
return - a / b * 1 / sympy.sqrt(-c / b) * sympy.atanh(symbol / sympy.sqrt(-c / b))
@evaluates(ReciprocalRule)
def eval_reciprocal(func, integrand, symbol):
return sympy.ln(func)
@evaluates(ArcsinRule)
def eval_arcsin(integrand, symbol):
return sympy.asin(symbol)
@evaluates(InverseHyperbolicRule)
def eval_inversehyperbolic(func, integrand, symbol):
return func(symbol)
@evaluates(AlternativeRule)
def eval_alternative(alternatives, integrand, symbol):
return _manualintegrate(alternatives[0])
@evaluates(RewriteRule)
def eval_rewrite(rewritten, substep, integrand, symbol):
return _manualintegrate(substep)
@evaluates(PiecewiseRule)
def eval_piecewise(substeps, integrand, symbol):
return sympy.Piecewise(*[(_manualintegrate(substep), cond)
for substep, cond in substeps])
@evaluates(TrigSubstitutionRule)
def eval_trigsubstitution(theta, func, rewritten, substep, restriction, integrand, symbol):
func = func.subs(sympy.sec(theta), 1/sympy.cos(theta))
func = func.subs(sympy.csc(theta), 1/sympy.sin(theta))
func = func.subs(sympy.cot(theta), 1/sympy.tan(theta))
trig_function = list(func.find(TrigonometricFunction))
assert len(trig_function) == 1
trig_function = trig_function[0]
relation = sympy.solve(symbol - func, trig_function)
assert len(relation) == 1
numer, denom = sympy.fraction(relation[0])
if isinstance(trig_function, sympy.sin):
opposite = numer
hypotenuse = denom
adjacent = sympy.sqrt(denom**2 - numer**2)
inverse = sympy.asin(relation[0])
elif isinstance(trig_function, sympy.cos):
adjacent = numer
hypotenuse = denom
opposite = sympy.sqrt(denom**2 - numer**2)
inverse = sympy.acos(relation[0])
elif isinstance(trig_function, sympy.tan):
opposite = numer
adjacent = denom
hypotenuse = sympy.sqrt(denom**2 + numer**2)
inverse = sympy.atan(relation[0])
substitution = [
(sympy.sin(theta), opposite/hypotenuse),
(sympy.cos(theta), adjacent/hypotenuse),
(sympy.tan(theta), opposite/adjacent),
(theta, inverse)
]
return sympy.Piecewise(
(_manualintegrate(substep).subs(substitution).trigsimp(), restriction)
)
@evaluates(DerivativeRule)
def eval_derivativerule(integrand, symbol):
# isinstance(integrand, Derivative) should be True
variable_count = list(integrand.variable_count)
for i, (var, count) in enumerate(variable_count):
if var == symbol:
variable_count[i] = (var, count-1)
break
return sympy.Derivative(integrand.expr, *variable_count)
@evaluates(HeavisideRule)
def eval_heaviside(harg, ibnd, substep, integrand, symbol):
# If we are integrating over x and the integrand has the form
# Heaviside(m*x+b)*g(x) == Heaviside(harg)*g(symbol)
# then there needs to be continuity at -b/m == ibnd,
# so we subtract the appropriate term.
return sympy.Heaviside(harg)*(substep - substep.subs(symbol, ibnd))
@evaluates(JacobiRule)
def eval_jacobi(n, a, b, integrand, symbol):
return Piecewise(
(2*sympy.jacobi(n + 1, a - 1, b - 1, symbol)/(n + a + b), Ne(n + a + b, 0)),
(symbol, Eq(n, 0)),
((a + b + 2)*symbol**2/4 + (a - b)*symbol/2, Eq(n, 1)))
@evaluates(GegenbauerRule)
def eval_gegenbauer(n, a, integrand, symbol):
return Piecewise(
(sympy.gegenbauer(n + 1, a - 1, symbol)/(2*(a - 1)), Ne(a, 1)),
(sympy.chebyshevt(n + 1, symbol)/(n + 1), Ne(n, -1)),
(sympy.S.Zero, True))
@evaluates(ChebyshevTRule)
def eval_chebyshevt(n, integrand, symbol):
return Piecewise(((sympy.chebyshevt(n + 1, symbol)/(n + 1) -
sympy.chebyshevt(n - 1, symbol)/(n - 1))/2, Ne(sympy.Abs(n), 1)),
(symbol**2/2, True))
@evaluates(ChebyshevURule)
def eval_chebyshevu(n, integrand, symbol):
return Piecewise(
(sympy.chebyshevt(n + 1, symbol)/(n + 1), Ne(n, -1)),
(sympy.S.Zero, True))
@evaluates(LegendreRule)
def eval_legendre(n, integrand, symbol):
return (sympy.legendre(n + 1, symbol) - sympy.legendre(n - 1, symbol))/(2*n + 1)
@evaluates(HermiteRule)
def eval_hermite(n, integrand, symbol):
return sympy.hermite(n + 1, symbol)/(2*(n + 1))
@evaluates(LaguerreRule)
def eval_laguerre(n, integrand, symbol):
return sympy.laguerre(n, symbol) - sympy.laguerre(n + 1, symbol)
@evaluates(AssocLaguerreRule)
def eval_assoclaguerre(n, a, integrand, symbol):
return -sympy.assoc_laguerre(n + 1, a - 1, symbol)
@evaluates(CiRule)
def eval_ci(a, b, integrand, symbol):
return sympy.cos(b)*sympy.Ci(a*symbol) - sympy.sin(b)*sympy.Si(a*symbol)
@evaluates(ChiRule)
def eval_chi(a, b, integrand, symbol):
return sympy.cosh(b)*sympy.Chi(a*symbol) + sympy.sinh(b)*sympy.Shi(a*symbol)
@evaluates(EiRule)
def eval_ei(a, b, integrand, symbol):
return sympy.exp(b)*sympy.Ei(a*symbol)
@evaluates(SiRule)
def eval_si(a, b, integrand, symbol):
return sympy.sin(b)*sympy.Ci(a*symbol) + sympy.cos(b)*sympy.Si(a*symbol)
@evaluates(ShiRule)
def eval_shi(a, b, integrand, symbol):
return sympy.sinh(b)*sympy.Chi(a*symbol) + sympy.cosh(b)*sympy.Shi(a*symbol)
@evaluates(ErfRule)
def eval_erf(a, b, c, integrand, symbol):
if a.is_extended_real:
return Piecewise(
(sympy.sqrt(sympy.pi/(-a))/2 * sympy.exp(c - b**2/(4*a)) *
sympy.erf((-2*a*symbol - b)/(2*sympy.sqrt(-a))), a < 0),
(sympy.sqrt(sympy.pi/a)/2 * sympy.exp(c - b**2/(4*a)) *
sympy.erfi((2*a*symbol + b)/(2*sympy.sqrt(a))), True))
else:
return sympy.sqrt(sympy.pi/a)/2 * sympy.exp(c - b**2/(4*a)) * \
sympy.erfi((2*a*symbol + b)/(2*sympy.sqrt(a)))
@evaluates(FresnelCRule)
def eval_fresnelc(a, b, c, integrand, symbol):
return sympy.sqrt(sympy.pi/(2*a)) * (
sympy.cos(b**2/(4*a) - c)*sympy.fresnelc((2*a*symbol + b)/sympy.sqrt(2*a*sympy.pi)) +
sympy.sin(b**2/(4*a) - c)*sympy.fresnels((2*a*symbol + b)/sympy.sqrt(2*a*sympy.pi)))
@evaluates(FresnelSRule)
def eval_fresnels(a, b, c, integrand, symbol):
return sympy.sqrt(sympy.pi/(2*a)) * (
sympy.cos(b**2/(4*a) - c)*sympy.fresnels((2*a*symbol + b)/sympy.sqrt(2*a*sympy.pi)) -
sympy.sin(b**2/(4*a) - c)*sympy.fresnelc((2*a*symbol + b)/sympy.sqrt(2*a*sympy.pi)))
@evaluates(LiRule)
def eval_li(a, b, integrand, symbol):
return sympy.li(a*symbol + b)/a
@evaluates(PolylogRule)
def eval_polylog(a, b, integrand, symbol):
return sympy.polylog(b + 1, a*symbol)
@evaluates(UpperGammaRule)
def eval_uppergamma(a, e, integrand, symbol):
return symbol**e * (-a*symbol)**(-e) * sympy.uppergamma(e + 1, -a*symbol)/a
@evaluates(EllipticFRule)
def eval_elliptic_f(a, d, integrand, symbol):
return sympy.elliptic_f(symbol, d/a)/sympy.sqrt(a)
@evaluates(EllipticERule)
def eval_elliptic_e(a, d, integrand, symbol):
return sympy.elliptic_e(symbol, d/a)*sympy.sqrt(a)
@evaluates(DontKnowRule)
def eval_dontknowrule(integrand, symbol):
return sympy.Integral(integrand, symbol)
def _manualintegrate(rule):
evaluator = evaluators.get(rule.__class__)
if not evaluator:
raise ValueError("Cannot evaluate rule %s" % repr(rule))
return evaluator(*rule)
def manualintegrate(f, var):
"""manualintegrate(f, var)
Explanation
===========
Compute indefinite integral of a single variable using an algorithm that
resembles what a student would do by hand.
Unlike :func:`~.integrate`, var can only be a single symbol.
Examples
========
>>> from sympy import sin, cos, tan, exp, log, integrate
>>> from sympy.integrals.manualintegrate import manualintegrate
>>> from sympy.abc import x
>>> manualintegrate(1 / x, x)
log(x)
>>> integrate(1/x)
log(x)
>>> manualintegrate(log(x), x)
x*log(x) - x
>>> integrate(log(x))
x*log(x) - x
>>> manualintegrate(exp(x) / (1 + exp(2 * x)), x)
atan(exp(x))
>>> integrate(exp(x) / (1 + exp(2 * x)))
RootSum(4*_z**2 + 1, Lambda(_i, _i*log(2*_i + exp(x))))
>>> manualintegrate(cos(x)**4 * sin(x), x)
-cos(x)**5/5
>>> integrate(cos(x)**4 * sin(x), x)
-cos(x)**5/5
>>> manualintegrate(cos(x)**4 * sin(x)**3, x)
cos(x)**7/7 - cos(x)**5/5
>>> integrate(cos(x)**4 * sin(x)**3, x)
cos(x)**7/7 - cos(x)**5/5
>>> manualintegrate(tan(x), x)
-log(cos(x))
>>> integrate(tan(x), x)
-log(cos(x))
See Also
========
sympy.integrals.integrals.integrate
sympy.integrals.integrals.Integral.doit
sympy.integrals.integrals.Integral
"""
result = _manualintegrate(integral_steps(f, var))
# Clear the cache of u-parts
_parts_u_cache.clear()
# If we got Piecewise with two parts, put generic first
if isinstance(result, Piecewise) and len(result.args) == 2:
cond = result.args[0][1]
if isinstance(cond, Eq) and result.args[1][1] == True:
result = result.func(
(result.args[1][0], sympy.Ne(*cond.args)),
(result.args[0][0], True))
return result
|
5a307afaa8688439f704b36f06cd226bfbe9127525b6ffd51caf0aa043eb9b20 | from sympy.concrete.expr_with_limits import AddWithLimits
from sympy.core.add import Add
from sympy.core.basic import Basic
from sympy.core.compatibility import is_sequence
from sympy.core.containers import Tuple
from sympy.core.expr import Expr
from sympy.core.function import diff
from sympy.core.logic import fuzzy_bool
from sympy.core.mul import Mul
from sympy.core.numbers import oo, pi
from sympy.core.relational import Ne
from sympy.core.singleton import S
from sympy.core.symbol import (Dummy, Symbol, Wild)
from sympy.core.sympify import sympify
from sympy.functions import Piecewise, sqrt, piecewise_fold, tan, cot, atan
from sympy.functions.elementary.exponential import log
from sympy.functions.elementary.integers import floor
from sympy.functions.elementary.complexes import Abs, sign
from sympy.functions.elementary.miscellaneous import Min, Max
from sympy.integrals.manualintegrate import manualintegrate
from sympy.integrals.trigonometry import trigintegrate
from sympy.integrals.meijerint import meijerint_definite, meijerint_indefinite
from sympy.matrices import MatrixBase
from sympy.polys import Poly, PolynomialError
from sympy.series import limit
from sympy.series.order import Order
from sympy.series.formal import FormalPowerSeries
from sympy.simplify.fu import sincos_to_sum
from sympy.tensor.functions import shape
from sympy.utilities.misc import filldedent
from sympy.utilities.exceptions import SymPyDeprecationWarning
class Integral(AddWithLimits):
"""Represents unevaluated integral."""
__slots__ = ('is_commutative',)
def __new__(cls, function, *symbols, **assumptions):
"""Create an unevaluated integral.
Explanation
===========
Arguments are an integrand followed by one or more limits.
If no limits are given and there is only one free symbol in the
expression, that symbol will be used, otherwise an error will be
raised.
>>> from sympy import Integral
>>> from sympy.abc import x, y
>>> Integral(x)
Integral(x, x)
>>> Integral(y)
Integral(y, y)
When limits are provided, they are interpreted as follows (using
``x`` as though it were the variable of integration):
(x,) or x - indefinite integral
(x, a) - "evaluate at" integral is an abstract antiderivative
(x, a, b) - definite integral
The ``as_dummy`` method can be used to see which symbols cannot be
targeted by subs: those with a prepended underscore cannot be
changed with ``subs``. (Also, the integration variables themselves --
the first element of a limit -- can never be changed by subs.)
>>> i = Integral(x, x)
>>> at = Integral(x, (x, x))
>>> i.as_dummy()
Integral(x, x)
>>> at.as_dummy()
Integral(_0, (_0, x))
"""
#This will help other classes define their own definitions
#of behaviour with Integral.
if hasattr(function, '_eval_Integral'):
return function._eval_Integral(*symbols, **assumptions)
if isinstance(function, Poly):
SymPyDeprecationWarning(
feature="Using integrate/Integral with Poly",
issue=18613,
deprecated_since_version="1.6",
useinstead="the as_expr or integrate methods of Poly").warn()
obj = AddWithLimits.__new__(cls, function, *symbols, **assumptions)
return obj
def __getnewargs__(self):
return (self.function,) + tuple([tuple(xab) for xab in self.limits])
@property
def free_symbols(self):
"""
This method returns the symbols that will exist when the
integral is evaluated. This is useful if one is trying to
determine whether an integral depends on a certain
symbol or not.
Examples
========
>>> from sympy import Integral
>>> from sympy.abc import x, y
>>> Integral(x, (x, y, 1)).free_symbols
{y}
See Also
========
sympy.concrete.expr_with_limits.ExprWithLimits.function
sympy.concrete.expr_with_limits.ExprWithLimits.limits
sympy.concrete.expr_with_limits.ExprWithLimits.variables
"""
return AddWithLimits.free_symbols.fget(self)
def _eval_is_zero(self):
# This is a very naive and quick test, not intended to do the integral to
# answer whether it is zero or not, e.g. Integral(sin(x), (x, 0, 2*pi))
# is zero but this routine should return None for that case. But, like
# Mul, there are trivial situations for which the integral will be
# zero so we check for those.
if self.function.is_zero:
return True
got_none = False
for l in self.limits:
if len(l) == 3:
z = (l[1] == l[2]) or (l[1] - l[2]).is_zero
if z:
return True
elif z is None:
got_none = True
free = self.function.free_symbols
for xab in self.limits:
if len(xab) == 1:
free.add(xab[0])
continue
if len(xab) == 2 and xab[0] not in free:
if xab[1].is_zero:
return True
elif xab[1].is_zero is None:
got_none = True
# take integration symbol out of free since it will be replaced
# with the free symbols in the limits
free.discard(xab[0])
# add in the new symbols
for i in xab[1:]:
free.update(i.free_symbols)
if self.function.is_zero is False and got_none is False:
return False
def transform(self, x, u):
r"""
Performs a change of variables from `x` to `u` using the relationship
given by `x` and `u` which will define the transformations `f` and `F`
(which are inverses of each other) as follows:
1) If `x` is a Symbol (which is a variable of integration) then `u`
will be interpreted as some function, f(u), with inverse F(u).
This, in effect, just makes the substitution of x with f(x).
2) If `u` is a Symbol then `x` will be interpreted as some function,
F(x), with inverse f(u). This is commonly referred to as
u-substitution.
Once f and F have been identified, the transformation is made as
follows:
.. math:: \int_a^b x \mathrm{d}x \rightarrow \int_{F(a)}^{F(b)} f(x)
\frac{\mathrm{d}}{\mathrm{d}x}
where `F(x)` is the inverse of `f(x)` and the limits and integrand have
been corrected so as to retain the same value after integration.
Notes
=====
The mappings, F(x) or f(u), must lead to a unique integral. Linear
or rational linear expression, ``2*x``, ``1/x`` and ``sqrt(x)``, will
always work; quadratic expressions like ``x**2 - 1`` are acceptable
as long as the resulting integrand does not depend on the sign of
the solutions (see examples).
The integral will be returned unchanged if ``x`` is not a variable of
integration.
``x`` must be (or contain) only one of of the integration variables. If
``u`` has more than one free symbol then it should be sent as a tuple
(``u``, ``uvar``) where ``uvar`` identifies which variable is replacing
the integration variable.
XXX can it contain another integration variable?
Examples
========
>>> from sympy.abc import a, x, u
>>> from sympy import Integral, cos, sqrt
>>> i = Integral(x*cos(x**2 - 1), (x, 0, 1))
transform can change the variable of integration
>>> i.transform(x, u)
Integral(u*cos(u**2 - 1), (u, 0, 1))
transform can perform u-substitution as long as a unique
integrand is obtained:
>>> i.transform(x**2 - 1, u)
Integral(cos(u)/2, (u, -1, 0))
This attempt fails because x = +/-sqrt(u + 1) and the
sign does not cancel out of the integrand:
>>> Integral(cos(x**2 - 1), (x, 0, 1)).transform(x**2 - 1, u)
Traceback (most recent call last):
...
ValueError:
The mapping between F(x) and f(u) did not give a unique integrand.
transform can do a substitution. Here, the previous
result is transformed back into the original expression
using "u-substitution":
>>> ui = _
>>> _.transform(sqrt(u + 1), x) == i
True
We can accomplish the same with a regular substitution:
>>> ui.transform(u, x**2 - 1) == i
True
If the `x` does not contain a symbol of integration then
the integral will be returned unchanged. Integral `i` does
not have an integration variable `a` so no change is made:
>>> i.transform(a, x) == i
True
When `u` has more than one free symbol the symbol that is
replacing `x` must be identified by passing `u` as a tuple:
>>> Integral(x, (x, 0, 1)).transform(x, (u + a, u))
Integral(a + u, (u, -a, 1 - a))
>>> Integral(x, (x, 0, 1)).transform(x, (u + a, a))
Integral(a + u, (a, -u, 1 - u))
See Also
========
sympy.concrete.expr_with_limits.ExprWithLimits.variables : Lists the integration variables
as_dummy : Replace integration variables with dummy ones
"""
from sympy.solvers.solvers import solve, posify
d = Dummy('d')
xfree = x.free_symbols.intersection(self.variables)
if len(xfree) > 1:
raise ValueError(
'F(x) can only contain one of: %s' % self.variables)
xvar = xfree.pop() if xfree else d
if xvar not in self.variables:
return self
u = sympify(u)
if isinstance(u, Expr):
ufree = u.free_symbols
if len(ufree) == 0:
raise ValueError(filldedent('''
f(u) cannot be a constant'''))
if len(ufree) > 1:
raise ValueError(filldedent('''
When f(u) has more than one free symbol, the one replacing x
must be identified: pass f(u) as (f(u), u)'''))
uvar = ufree.pop()
else:
u, uvar = u
if uvar not in u.free_symbols:
raise ValueError(filldedent('''
Expecting a tuple (expr, symbol) where symbol identified
a free symbol in expr, but symbol is not in expr's free
symbols.'''))
if not isinstance(uvar, Symbol):
# This probably never evaluates to True
raise ValueError(filldedent('''
Expecting a tuple (expr, symbol) but didn't get
a symbol; got %s''' % uvar))
if x.is_Symbol and u.is_Symbol:
return self.xreplace({x: u})
if not x.is_Symbol and not u.is_Symbol:
raise ValueError('either x or u must be a symbol')
if uvar == xvar:
return self.transform(x, (u.subs(uvar, d), d)).xreplace({d: uvar})
if uvar in self.limits:
raise ValueError(filldedent('''
u must contain the same variable as in x
or a variable that is not already an integration variable'''))
if not x.is_Symbol:
F = [x.subs(xvar, d)]
soln = solve(u - x, xvar, check=False)
if not soln:
raise ValueError('no solution for solve(F(x) - f(u), x)')
f = [fi.subs(uvar, d) for fi in soln]
else:
f = [u.subs(uvar, d)]
pdiff, reps = posify(u - x)
puvar = uvar.subs([(v, k) for k, v in reps.items()])
soln = [s.subs(reps) for s in solve(pdiff, puvar)]
if not soln:
raise ValueError('no solution for solve(F(x) - f(u), u)')
F = [fi.subs(xvar, d) for fi in soln]
newfuncs = {(self.function.subs(xvar, fi)*fi.diff(d)
).subs(d, uvar) for fi in f}
if len(newfuncs) > 1:
raise ValueError(filldedent('''
The mapping between F(x) and f(u) did not give
a unique integrand.'''))
newfunc = newfuncs.pop()
def _calc_limit_1(F, a, b):
"""
replace d with a, using subs if possible, otherwise limit
where sign of b is considered
"""
wok = F.subs(d, a)
if wok is S.NaN or wok.is_finite is False and a.is_finite:
return limit(sign(b)*F, d, a)
return wok
def _calc_limit(a, b):
"""
replace d with a, using subs if possible, otherwise limit
where sign of b is considered
"""
avals = list({_calc_limit_1(Fi, a, b) for Fi in F})
if len(avals) > 1:
raise ValueError(filldedent('''
The mapping between F(x) and f(u) did not
give a unique limit.'''))
return avals[0]
newlimits = []
for xab in self.limits:
sym = xab[0]
if sym == xvar:
if len(xab) == 3:
a, b = xab[1:]
a, b = _calc_limit(a, b), _calc_limit(b, a)
if fuzzy_bool(a - b > 0):
a, b = b, a
newfunc = -newfunc
newlimits.append((uvar, a, b))
elif len(xab) == 2:
a = _calc_limit(xab[1], 1)
newlimits.append((uvar, a))
else:
newlimits.append(uvar)
else:
newlimits.append(xab)
return self.func(newfunc, *newlimits)
def doit(self, **hints):
"""
Perform the integration using any hints given.
Examples
========
>>> from sympy import Piecewise, S
>>> from sympy.abc import x, t
>>> p = x**2 + Piecewise((0, x/t < 0), (1, True))
>>> p.integrate((t, S(4)/5, 1), (x, -1, 1))
1/3
See Also
========
sympy.integrals.trigonometry.trigintegrate
sympy.integrals.heurisch.heurisch
sympy.integrals.rationaltools.ratint
as_sum : Approximate the integral using a sum
"""
from sympy.concrete.summations import Sum
if not hints.get('integrals', True):
return self
deep = hints.get('deep', True)
meijerg = hints.get('meijerg', None)
conds = hints.get('conds', 'piecewise')
risch = hints.get('risch', None)
heurisch = hints.get('heurisch', None)
manual = hints.get('manual', None)
if len(list(filter(None, (manual, meijerg, risch, heurisch)))) > 1:
raise ValueError("At most one of manual, meijerg, risch, heurisch can be True")
elif manual:
meijerg = risch = heurisch = False
elif meijerg:
manual = risch = heurisch = False
elif risch:
manual = meijerg = heurisch = False
elif heurisch:
manual = meijerg = risch = False
eval_kwargs = dict(meijerg=meijerg, risch=risch, manual=manual, heurisch=heurisch,
conds=conds)
if conds not in ['separate', 'piecewise', 'none']:
raise ValueError('conds must be one of "separate", "piecewise", '
'"none", got: %s' % conds)
if risch and any(len(xab) > 1 for xab in self.limits):
raise ValueError('risch=True is only allowed for indefinite integrals.')
# check for the trivial zero
if self.is_zero:
return S.Zero
# hacks to handle integrals of
# nested summations
if isinstance(self.function, Sum):
if any(v in self.function.limits[0] for v in self.variables):
raise ValueError('Limit of the sum cannot be an integration variable.')
if any(l.is_infinite for l in self.function.limits[0][1:]):
return self
_i = self
_sum = self.function
return _sum.func(_i.func(_sum.function, *_i.limits).doit(), *_sum.limits).doit()
# now compute and check the function
function = self.function
if deep:
function = function.doit(**hints)
if function.is_zero:
return S.Zero
# hacks to handle special cases
if isinstance(function, MatrixBase):
return function.applyfunc(
lambda f: self.func(f, self.limits).doit(**hints))
if isinstance(function, FormalPowerSeries):
if len(self.limits) > 1:
raise NotImplementedError
xab = self.limits[0]
if len(xab) > 1:
return function.integrate(xab, **eval_kwargs)
else:
return function.integrate(xab[0], **eval_kwargs)
# There is no trivial answer and special handling
# is done so continue
# first make sure any definite limits have integration
# variables with matching assumptions
reps = {}
for xab in self.limits:
if len(xab) != 3:
continue
x, a, b = xab
l = (a, b)
if all(i.is_nonnegative for i in l) and not x.is_nonnegative:
d = Dummy(positive=True)
elif all(i.is_nonpositive for i in l) and not x.is_nonpositive:
d = Dummy(negative=True)
elif all(i.is_real for i in l) and not x.is_real:
d = Dummy(real=True)
else:
d = None
if d:
reps[x] = d
if reps:
undo = {v: k for k, v in reps.items()}
did = self.xreplace(reps).doit(**hints)
if type(did) is tuple: # when separate=True
did = tuple([i.xreplace(undo) for i in did])
else:
did = did.xreplace(undo)
return did
# continue with existing assumptions
undone_limits = []
# ulj = free symbols of any undone limits' upper and lower limits
ulj = set()
for xab in self.limits:
# compute uli, the free symbols in the
# Upper and Lower limits of limit I
if len(xab) == 1:
uli = set(xab[:1])
elif len(xab) == 2:
uli = xab[1].free_symbols
elif len(xab) == 3:
uli = xab[1].free_symbols.union(xab[2].free_symbols)
# this integral can be done as long as there is no blocking
# limit that has been undone. An undone limit is blocking if
# it contains an integration variable that is in this limit's
# upper or lower free symbols or vice versa
if xab[0] in ulj or any(v[0] in uli for v in undone_limits):
undone_limits.append(xab)
ulj.update(uli)
function = self.func(*([function] + [xab]))
factored_function = function.factor()
if not isinstance(factored_function, Integral):
function = factored_function
continue
if function.has(Abs, sign) and (
(len(xab) < 3 and all(x.is_extended_real for x in xab)) or
(len(xab) == 3 and all(x.is_extended_real and not x.is_infinite for
x in xab[1:]))):
# some improper integrals are better off with Abs
xr = Dummy("xr", real=True)
function = (function.xreplace({xab[0]: xr})
.rewrite(Piecewise).xreplace({xr: xab[0]}))
elif function.has(Min, Max):
function = function.rewrite(Piecewise)
if (function.has(Piecewise) and
not isinstance(function, Piecewise)):
function = piecewise_fold(function)
if isinstance(function, Piecewise):
if len(xab) == 1:
antideriv = function._eval_integral(xab[0],
**eval_kwargs)
else:
antideriv = self._eval_integral(
function, xab[0], **eval_kwargs)
else:
# There are a number of tradeoffs in using the
# Meijer G method. It can sometimes be a lot faster
# than other methods, and sometimes slower. And
# there are certain types of integrals for which it
# is more likely to work than others. These
# heuristics are incorporated in deciding what
# integration methods to try, in what order. See the
# integrate() docstring for details.
def try_meijerg(function, xab):
ret = None
if len(xab) == 3 and meijerg is not False:
x, a, b = xab
try:
res = meijerint_definite(function, x, a, b)
except NotImplementedError:
from sympy.integrals.meijerint import _debug
_debug('NotImplementedError '
'from meijerint_definite')
res = None
if res is not None:
f, cond = res
if conds == 'piecewise':
ret = Piecewise(
(f, cond),
(self.func(
function, (x, a, b)), True))
elif conds == 'separate':
if len(self.limits) != 1:
raise ValueError(filldedent('''
conds=separate not supported in
multiple integrals'''))
ret = f, cond
else:
ret = f
return ret
meijerg1 = meijerg
if (meijerg is not False and
len(xab) == 3 and xab[1].is_extended_real and xab[2].is_extended_real
and not function.is_Poly and
(xab[1].has(oo, -oo) or xab[2].has(oo, -oo))):
ret = try_meijerg(function, xab)
if ret is not None:
function = ret
continue
meijerg1 = False
# If the special meijerg code did not succeed in
# finding a definite integral, then the code using
# meijerint_indefinite will not either (it might
# find an antiderivative, but the answer is likely
# to be nonsensical). Thus if we are requested to
# only use Meijer G-function methods, we give up at
# this stage. Otherwise we just disable G-function
# methods.
if meijerg1 is False and meijerg is True:
antideriv = None
else:
antideriv = self._eval_integral(
function, xab[0], **eval_kwargs)
if antideriv is None and meijerg is True:
ret = try_meijerg(function, xab)
if ret is not None:
function = ret
continue
final = hints.get('final', True)
# dotit may be iterated but floor terms making atan and acot
# continous should only be added in the final round
if (final and not isinstance(antideriv, Integral) and
antideriv is not None):
for atan_term in antideriv.atoms(atan):
atan_arg = atan_term.args[0]
# Checking `atan_arg` to be linear combination of `tan` or `cot`
for tan_part in atan_arg.atoms(tan):
x1 = Dummy('x1')
tan_exp1 = atan_arg.subs(tan_part, x1)
# The coefficient of `tan` should be constant
coeff = tan_exp1.diff(x1)
if x1 not in coeff.free_symbols:
a = tan_part.args[0]
antideriv = antideriv.subs(atan_term, Add(atan_term,
sign(coeff)*pi*floor((a-pi/2)/pi)))
for cot_part in atan_arg.atoms(cot):
x1 = Dummy('x1')
cot_exp1 = atan_arg.subs(cot_part, x1)
# The coefficient of `cot` should be constant
coeff = cot_exp1.diff(x1)
if x1 not in coeff.free_symbols:
a = cot_part.args[0]
antideriv = antideriv.subs(atan_term, Add(atan_term,
sign(coeff)*pi*floor((a)/pi)))
if antideriv is None:
undone_limits.append(xab)
function = self.func(*([function] + [xab])).factor()
factored_function = function.factor()
if not isinstance(factored_function, Integral):
function = factored_function
continue
else:
if len(xab) == 1:
function = antideriv
else:
if len(xab) == 3:
x, a, b = xab
elif len(xab) == 2:
x, b = xab
a = None
else:
raise NotImplementedError
if deep:
if isinstance(a, Basic):
a = a.doit(**hints)
if isinstance(b, Basic):
b = b.doit(**hints)
if antideriv.is_Poly:
gens = list(antideriv.gens)
gens.remove(x)
antideriv = antideriv.as_expr()
function = antideriv._eval_interval(x, a, b)
function = Poly(function, *gens)
else:
def is_indef_int(g, x):
return (isinstance(g, Integral) and
any(i == (x,) for i in g.limits))
def eval_factored(f, x, a, b):
# _eval_interval for integrals with
# (constant) factors
# a single indefinite integral is assumed
args = []
for g in Mul.make_args(f):
if is_indef_int(g, x):
args.append(g._eval_interval(x, a, b))
else:
args.append(g)
return Mul(*args)
integrals, others, piecewises = [], [], []
for f in Add.make_args(antideriv):
if any(is_indef_int(g, x)
for g in Mul.make_args(f)):
integrals.append(f)
elif any(isinstance(g, Piecewise)
for g in Mul.make_args(f)):
piecewises.append(piecewise_fold(f))
else:
others.append(f)
uneval = Add(*[eval_factored(f, x, a, b)
for f in integrals])
try:
evalued = Add(*others)._eval_interval(x, a, b)
evalued_pw = piecewise_fold(Add(*piecewises))._eval_interval(x, a, b)
function = uneval + evalued + evalued_pw
except NotImplementedError:
# This can happen if _eval_interval depends in a
# complicated way on limits that cannot be computed
undone_limits.append(xab)
function = self.func(*([function] + [xab]))
factored_function = function.factor()
if not isinstance(factored_function, Integral):
function = factored_function
return function
def _eval_derivative(self, sym):
"""Evaluate the derivative of the current Integral object by
differentiating under the integral sign [1], using the Fundamental
Theorem of Calculus [2] when possible.
Explanation
===========
Whenever an Integral is encountered that is equivalent to zero or
has an integrand that is independent of the variable of integration
those integrals are performed. All others are returned as Integral
instances which can be resolved with doit() (provided they are integrable).
References
==========
.. [1] https://en.wikipedia.org/wiki/Differentiation_under_the_integral_sign
.. [2] https://en.wikipedia.org/wiki/Fundamental_theorem_of_calculus
Examples
========
>>> from sympy import Integral
>>> from sympy.abc import x, y
>>> i = Integral(x + y, y, (y, 1, x))
>>> i.diff(x)
Integral(x + y, (y, x)) + Integral(1, y, (y, 1, x))
>>> i.doit().diff(x) == i.diff(x).doit()
True
>>> i.diff(y)
0
The previous must be true since there is no y in the evaluated integral:
>>> i.free_symbols
{x}
>>> i.doit()
2*x**3/3 - x/2 - 1/6
"""
# differentiate under the integral sign; we do not
# check for regularity conditions (TODO), see issue 4215
# get limits and the function
f, limits = self.function, list(self.limits)
# the order matters if variables of integration appear in the limits
# so work our way in from the outside to the inside.
limit = limits.pop(-1)
if len(limit) == 3:
x, a, b = limit
elif len(limit) == 2:
x, b = limit
a = None
else:
a = b = None
x = limit[0]
if limits: # f is the argument to an integral
f = self.func(f, *tuple(limits))
# assemble the pieces
def _do(f, ab):
dab_dsym = diff(ab, sym)
if not dab_dsym:
return S.Zero
if isinstance(f, Integral):
limits = [(x, x) if (len(l) == 1 and l[0] == x) else l
for l in f.limits]
f = self.func(f.function, *limits)
return f.subs(x, ab)*dab_dsym
rv = S.Zero
if b is not None:
rv += _do(f, b)
if a is not None:
rv -= _do(f, a)
if len(limit) == 1 and sym == x:
# the dummy variable *is* also the real-world variable
arg = f
rv += arg
else:
# the dummy variable might match sym but it's
# only a dummy and the actual variable is determined
# by the limits, so mask off the variable of integration
# while differentiating
u = Dummy('u')
arg = f.subs(x, u).diff(sym).subs(u, x)
if arg:
rv += self.func(arg, Tuple(x, a, b))
return rv
def _eval_integral(self, f, x, meijerg=None, risch=None, manual=None,
heurisch=None, conds='piecewise',final=None):
"""
Calculate the anti-derivative to the function f(x).
Explanation
===========
The following algorithms are applied (roughly in this order):
1. Simple heuristics (based on pattern matching and integral table):
- most frequently used functions (e.g. polynomials, products of
trig functions)
2. Integration of rational functions:
- A complete algorithm for integrating rational functions is
implemented (the Lazard-Rioboo-Trager algorithm). The algorithm
also uses the partial fraction decomposition algorithm
implemented in apart() as a preprocessor to make this process
faster. Note that the integral of a rational function is always
elementary, but in general, it may include a RootSum.
3. Full Risch algorithm:
- The Risch algorithm is a complete decision
procedure for integrating elementary functions, which means that
given any elementary function, it will either compute an
elementary antiderivative, or else prove that none exists.
Currently, part of transcendental case is implemented, meaning
elementary integrals containing exponentials, logarithms, and
(soon!) trigonometric functions can be computed. The algebraic
case, e.g., functions containing roots, is much more difficult
and is not implemented yet.
- If the routine fails (because the integrand is not elementary, or
because a case is not implemented yet), it continues on to the
next algorithms below. If the routine proves that the integrals
is nonelementary, it still moves on to the algorithms below,
because we might be able to find a closed-form solution in terms
of special functions. If risch=True, however, it will stop here.
4. The Meijer G-Function algorithm:
- This algorithm works by first rewriting the integrand in terms of
very general Meijer G-Function (meijerg in SymPy), integrating
it, and then rewriting the result back, if possible. This
algorithm is particularly powerful for definite integrals (which
is actually part of a different method of Integral), since it can
compute closed-form solutions of definite integrals even when no
closed-form indefinite integral exists. But it also is capable
of computing many indefinite integrals as well.
- Another advantage of this method is that it can use some results
about the Meijer G-Function to give a result in terms of a
Piecewise expression, which allows to express conditionally
convergent integrals.
- Setting meijerg=True will cause integrate() to use only this
method.
5. The "manual integration" algorithm:
- This algorithm tries to mimic how a person would find an
antiderivative by hand, for example by looking for a
substitution or applying integration by parts. This algorithm
does not handle as many integrands but can return results in a
more familiar form.
- Sometimes this algorithm can evaluate parts of an integral; in
this case integrate() will try to evaluate the rest of the
integrand using the other methods here.
- Setting manual=True will cause integrate() to use only this
method.
6. The Heuristic Risch algorithm:
- This is a heuristic version of the Risch algorithm, meaning that
it is not deterministic. This is tried as a last resort because
it can be very slow. It is still used because not enough of the
full Risch algorithm is implemented, so that there are still some
integrals that can only be computed using this method. The goal
is to implement enough of the Risch and Meijer G-function methods
so that this can be deleted.
Setting heurisch=True will cause integrate() to use only this
method. Set heurisch=False to not use it.
"""
from sympy.integrals.deltafunctions import deltaintegrate
from sympy.integrals.singularityfunctions import singularityintegrate
from sympy.integrals.heurisch import heurisch as heurisch_, heurisch_wrapper
from sympy.integrals.rationaltools import ratint
from sympy.integrals.risch import risch_integrate
if risch:
try:
return risch_integrate(f, x, conds=conds)
except NotImplementedError:
return None
if manual:
try:
result = manualintegrate(f, x)
if result is not None and result.func != Integral:
return result
except (ValueError, PolynomialError):
pass
eval_kwargs = dict(meijerg=meijerg, risch=risch, manual=manual,
heurisch=heurisch, conds=conds)
# if it is a poly(x) then let the polynomial integrate itself (fast)
#
# It is important to make this check first, otherwise the other code
# will return a sympy expression instead of a Polynomial.
#
# see Polynomial for details.
if isinstance(f, Poly) and not (manual or meijerg or risch):
SymPyDeprecationWarning(
feature="Using integrate/Integral with Poly",
issue=18613,
deprecated_since_version="1.6",
useinstead="the as_expr or integrate methods of Poly").warn()
return f.integrate(x)
# Piecewise antiderivatives need to call special integrate.
if isinstance(f, Piecewise):
return f.piecewise_integrate(x, **eval_kwargs)
# let's cut it short if `f` does not depend on `x`; if
# x is only a dummy, that will be handled below
if not f.has(x):
return f*x
# try to convert to poly(x) and then integrate if successful (fast)
poly = f.as_poly(x)
if poly is not None and not (manual or meijerg or risch):
return poly.integrate().as_expr()
if risch is not False:
try:
result, i = risch_integrate(f, x, separate_integral=True,
conds=conds)
except NotImplementedError:
pass
else:
if i:
# There was a nonelementary integral. Try integrating it.
# if no part of the NonElementaryIntegral is integrated by
# the Risch algorithm, then use the original function to
# integrate, instead of re-written one
if result == 0:
from sympy.integrals.risch import NonElementaryIntegral
return NonElementaryIntegral(f, x).doit(risch=False)
else:
return result + i.doit(risch=False)
else:
return result
# since Integral(f=g1+g2+...) == Integral(g1) + Integral(g2) + ...
# we are going to handle Add terms separately,
# if `f` is not Add -- we only have one term
# Note that in general, this is a bad idea, because Integral(g1) +
# Integral(g2) might not be computable, even if Integral(g1 + g2) is.
# For example, Integral(x**x + x**x*log(x)). But many heuristics only
# work term-wise. So we compute this step last, after trying
# risch_integrate. We also try risch_integrate again in this loop,
# because maybe the integral is a sum of an elementary part and a
# nonelementary part (like erf(x) + exp(x)). risch_integrate() is
# quite fast, so this is acceptable.
parts = []
args = Add.make_args(f)
for g in args:
coeff, g = g.as_independent(x)
# g(x) = const
if g is S.One and not meijerg:
parts.append(coeff*x)
continue
# g(x) = expr + O(x**n)
order_term = g.getO()
if order_term is not None:
h = self._eval_integral(g.removeO(), x, **eval_kwargs)
if h is not None:
h_order_expr = self._eval_integral(order_term.expr, x, **eval_kwargs)
if h_order_expr is not None:
h_order_term = order_term.func(
h_order_expr, *order_term.variables)
parts.append(coeff*(h + h_order_term))
continue
# NOTE: if there is O(x**n) and we fail to integrate then
# there is no point in trying other methods because they
# will fail, too.
return None
# c
# g(x) = (a*x+b)
if g.is_Pow and not g.exp.has(x) and not meijerg:
a = Wild('a', exclude=[x])
b = Wild('b', exclude=[x])
M = g.base.match(a*x + b)
if M is not None:
if g.exp == -1:
h = log(g.base)
elif conds != 'piecewise':
h = g.base**(g.exp + 1) / (g.exp + 1)
else:
h1 = log(g.base)
h2 = g.base**(g.exp + 1) / (g.exp + 1)
h = Piecewise((h2, Ne(g.exp, -1)), (h1, True))
parts.append(coeff * h / M[a])
continue
# poly(x)
# g(x) = -------
# poly(x)
if g.is_rational_function(x) and not (manual or meijerg or risch):
parts.append(coeff * ratint(g, x))
continue
if not (manual or meijerg or risch):
# g(x) = Mul(trig)
h = trigintegrate(g, x, conds=conds)
if h is not None:
parts.append(coeff * h)
continue
# g(x) has at least a DiracDelta term
h = deltaintegrate(g, x)
if h is not None:
parts.append(coeff * h)
continue
# g(x) has at least a Singularity Function term
h = singularityintegrate(g, x)
if h is not None:
parts.append(coeff * h)
continue
# Try risch again.
if risch is not False:
try:
h, i = risch_integrate(g, x,
separate_integral=True, conds=conds)
except NotImplementedError:
h = None
else:
if i:
h = h + i.doit(risch=False)
parts.append(coeff*h)
continue
# fall back to heurisch
if heurisch is not False:
try:
if conds == 'piecewise':
h = heurisch_wrapper(g, x, hints=[])
else:
h = heurisch_(g, x, hints=[])
except PolynomialError:
# XXX: this exception means there is a bug in the
# implementation of heuristic Risch integration
# algorithm.
h = None
else:
h = None
if meijerg is not False and h is None:
# rewrite using G functions
try:
h = meijerint_indefinite(g, x)
except NotImplementedError:
from sympy.integrals.meijerint import _debug
_debug('NotImplementedError from meijerint_definite')
if h is not None:
parts.append(coeff * h)
continue
if h is None and manual is not False:
try:
result = manualintegrate(g, x)
if result is not None and not isinstance(result, Integral):
if result.has(Integral) and not manual:
# Try to have other algorithms do the integrals
# manualintegrate can't handle,
# unless we were asked to use manual only.
# Keep the rest of eval_kwargs in case another
# method was set to False already
new_eval_kwargs = eval_kwargs
new_eval_kwargs["manual"] = False
new_eval_kwargs["final"] = False
result = result.func(*[
arg.doit(**new_eval_kwargs) if
arg.has(Integral) else arg
for arg in result.args
]).expand(multinomial=False,
log=False,
power_exp=False,
power_base=False)
if not result.has(Integral):
parts.append(coeff * result)
continue
except (ValueError, PolynomialError):
# can't handle some SymPy expressions
pass
# if we failed maybe it was because we had
# a product that could have been expanded,
# so let's try an expansion of the whole
# thing before giving up; we don't try this
# at the outset because there are things
# that cannot be solved unless they are
# NOT expanded e.g., x**x*(1+log(x)). There
# should probably be a checker somewhere in this
# routine to look for such cases and try to do
# collection on the expressions if they are already
# in an expanded form
if not h and len(args) == 1:
f = sincos_to_sum(f).expand(mul=True, deep=False)
if f.is_Add:
# Note: risch will be identical on the expanded
# expression, but maybe it will be able to pick out parts,
# like x*(exp(x) + erf(x)).
return self._eval_integral(f, x, **eval_kwargs)
if h is not None:
parts.append(coeff * h)
else:
return None
return Add(*parts)
def _eval_lseries(self, x, logx=None, cdir=0):
expr = self.as_dummy()
symb = x
for l in expr.limits:
if x in l[1:]:
symb = l[0]
break
for term in expr.function.lseries(symb, logx):
yield integrate(term, *expr.limits)
def _eval_nseries(self, x, n, logx=None, cdir=0):
expr = self.as_dummy()
symb = x
for l in expr.limits:
if x in l[1:]:
symb = l[0]
break
terms, order = expr.function.nseries(
x=symb, n=n, logx=logx).as_coeff_add(Order)
order = [o.subs(symb, x) for o in order]
return integrate(terms, *expr.limits) + Add(*order)*x
def _eval_as_leading_term(self, x, logx=None, cdir=0):
series_gen = self.args[0].lseries(x)
for leading_term in series_gen:
if leading_term != 0:
break
return integrate(leading_term, *self.args[1:])
def _eval_simplify(self, **kwargs):
from sympy.core.exprtools import factor_terms
from sympy.simplify.simplify import simplify
expr = factor_terms(self)
if isinstance(expr, Integral):
return expr.func(*[simplify(i, **kwargs) for i in expr.args])
return expr.simplify(**kwargs)
def as_sum(self, n=None, method="midpoint", evaluate=True):
"""
Approximates a definite integral by a sum.
Parameters
==========
n :
The number of subintervals to use, optional.
method :
One of: 'left', 'right', 'midpoint', 'trapezoid'.
evaluate : bool
If False, returns an unevaluated Sum expression. The default
is True, evaluate the sum.
Notes
=====
These methods of approximate integration are described in [1].
Examples
========
>>> from sympy import sin, sqrt
>>> from sympy.abc import x, n
>>> from sympy.integrals import Integral
>>> e = Integral(sin(x), (x, 3, 7))
>>> e
Integral(sin(x), (x, 3, 7))
For demonstration purposes, this interval will only be split into 2
regions, bounded by [3, 5] and [5, 7].
The left-hand rule uses function evaluations at the left of each
interval:
>>> e.as_sum(2, 'left')
2*sin(5) + 2*sin(3)
The midpoint rule uses evaluations at the center of each interval:
>>> e.as_sum(2, 'midpoint')
2*sin(4) + 2*sin(6)
The right-hand rule uses function evaluations at the right of each
interval:
>>> e.as_sum(2, 'right')
2*sin(5) + 2*sin(7)
The trapezoid rule uses function evaluations on both sides of the
intervals. This is equivalent to taking the average of the left and
right hand rule results:
>>> e.as_sum(2, 'trapezoid')
2*sin(5) + sin(3) + sin(7)
>>> (e.as_sum(2, 'left') + e.as_sum(2, 'right'))/2 == _
True
Here, the discontinuity at x = 0 can be avoided by using the
midpoint or right-hand method:
>>> e = Integral(1/sqrt(x), (x, 0, 1))
>>> e.as_sum(5).n(4)
1.730
>>> e.as_sum(10).n(4)
1.809
>>> e.doit().n(4) # the actual value is 2
2.000
The left- or trapezoid method will encounter the discontinuity and
return infinity:
>>> e.as_sum(5, 'left')
zoo
The number of intervals can be symbolic. If omitted, a dummy symbol
will be used for it.
>>> e = Integral(x**2, (x, 0, 2))
>>> e.as_sum(n, 'right').expand()
8/3 + 4/n + 4/(3*n**2)
This shows that the midpoint rule is more accurate, as its error
term decays as the square of n:
>>> e.as_sum(method='midpoint').expand()
8/3 - 2/(3*_n**2)
A symbolic sum is returned with evaluate=False:
>>> e.as_sum(n, 'midpoint', evaluate=False)
2*Sum((2*_k/n - 1/n)**2, (_k, 1, n))/n
See Also
========
Integral.doit : Perform the integration using any hints
References
==========
.. [1] https://en.wikipedia.org/wiki/Riemann_sum#Methods
"""
from sympy.concrete.summations import Sum
limits = self.limits
if len(limits) > 1:
raise NotImplementedError(
"Multidimensional midpoint rule not implemented yet")
else:
limit = limits[0]
if (len(limit) != 3 or limit[1].is_finite is False or
limit[2].is_finite is False):
raise ValueError("Expecting a definite integral over "
"a finite interval.")
if n is None:
n = Dummy('n', integer=True, positive=True)
else:
n = sympify(n)
if (n.is_positive is False or n.is_integer is False or
n.is_finite is False):
raise ValueError("n must be a positive integer, got %s" % n)
x, a, b = limit
dx = (b - a)/n
k = Dummy('k', integer=True, positive=True)
f = self.function
if method == "left":
result = dx*Sum(f.subs(x, a + (k-1)*dx), (k, 1, n))
elif method == "right":
result = dx*Sum(f.subs(x, a + k*dx), (k, 1, n))
elif method == "midpoint":
result = dx*Sum(f.subs(x, a + k*dx - dx/2), (k, 1, n))
elif method == "trapezoid":
result = dx*((f.subs(x, a) + f.subs(x, b))/2 +
Sum(f.subs(x, a + k*dx), (k, 1, n - 1)))
else:
raise ValueError("Unknown method %s" % method)
return result.doit() if evaluate else result
def _sage_(self):
import sage.all as sage
f, limits = self.function._sage_(), list(self.limits)
for limit_ in limits:
if len(limit_) == 1:
x = limit_[0]
f = sage.integral(f,
x._sage_(),
hold=True)
elif len(limit_) == 2:
x, b = limit_
f = sage.integral(f,
x._sage_(),
b._sage_(),
hold=True)
else:
x, a, b = limit_
f = sage.integral(f,
(x._sage_(),
a._sage_(),
b._sage_()),
hold=True)
return f
def principal_value(self, **kwargs):
"""
Compute the Cauchy Principal Value of the definite integral of a real function in the given interval
on the real axis.
Explanation
===========
In mathematics, the Cauchy principal value, is a method for assigning values to certain improper
integrals which would otherwise be undefined.
Examples
========
>>> from sympy import oo
>>> from sympy.integrals.integrals import Integral
>>> from sympy.abc import x
>>> Integral(x+1, (x, -oo, oo)).principal_value()
oo
>>> f = 1 / (x**3)
>>> Integral(f, (x, -oo, oo)).principal_value()
0
>>> Integral(f, (x, -10, 10)).principal_value()
0
>>> Integral(f, (x, -10, oo)).principal_value() + Integral(f, (x, -oo, 10)).principal_value()
0
References
==========
.. [1] https://en.wikipedia.org/wiki/Cauchy_principal_value
.. [2] http://mathworld.wolfram.com/CauchyPrincipalValue.html
"""
from sympy.calculus import singularities
if len(self.limits) != 1 or len(list(self.limits[0])) != 3:
raise ValueError("You need to insert a variable, lower_limit, and upper_limit correctly to calculate "
"cauchy's principal value")
x, a, b = self.limits[0]
if not (a.is_comparable and b.is_comparable and a <= b):
raise ValueError("The lower_limit must be smaller than or equal to the upper_limit to calculate "
"cauchy's principal value. Also, a and b need to be comparable.")
if a == b:
return 0
r = Dummy('r')
f = self.function
singularities_list = [s for s in singularities(f, x) if s.is_comparable and a <= s <= b]
for i in singularities_list:
if (i == b) or (i == a):
raise ValueError(
'The principal value is not defined in the given interval due to singularity at %d.' % (i))
F = integrate(f, x, **kwargs)
if F.has(Integral):
return self
if a is -oo and b is oo:
I = limit(F - F.subs(x, -x), x, oo)
else:
I = limit(F, x, b, '-') - limit(F, x, a, '+')
for s in singularities_list:
I += limit(((F.subs(x, s - r)) - F.subs(x, s + r)), r, 0, '+')
return I
def integrate(*args, meijerg=None, conds='piecewise', risch=None, heurisch=None, manual=None, **kwargs):
"""integrate(f, var, ...)
Explanation
===========
Compute definite or indefinite integral of one or more variables
using Risch-Norman algorithm and table lookup. This procedure is
able to handle elementary algebraic and transcendental functions
and also a huge class of special functions, including Airy,
Bessel, Whittaker and Lambert.
var can be:
- a symbol -- indefinite integration
- a tuple (symbol, a) -- indefinite integration with result
given with `a` replacing `symbol`
- a tuple (symbol, a, b) -- definite integration
Several variables can be specified, in which case the result is
multiple integration. (If var is omitted and the integrand is
univariate, the indefinite integral in that variable will be performed.)
Indefinite integrals are returned without terms that are independent
of the integration variables. (see examples)
Definite improper integrals often entail delicate convergence
conditions. Pass conds='piecewise', 'separate' or 'none' to have
these returned, respectively, as a Piecewise function, as a separate
result (i.e. result will be a tuple), or not at all (default is
'piecewise').
**Strategy**
SymPy uses various approaches to definite integration. One method is to
find an antiderivative for the integrand, and then use the fundamental
theorem of calculus. Various functions are implemented to integrate
polynomial, rational and trigonometric functions, and integrands
containing DiracDelta terms.
SymPy also implements the part of the Risch algorithm, which is a decision
procedure for integrating elementary functions, i.e., the algorithm can
either find an elementary antiderivative, or prove that one does not
exist. There is also a (very successful, albeit somewhat slow) general
implementation of the heuristic Risch algorithm. This algorithm will
eventually be phased out as more of the full Risch algorithm is
implemented. See the docstring of Integral._eval_integral() for more
details on computing the antiderivative using algebraic methods.
The option risch=True can be used to use only the (full) Risch algorithm.
This is useful if you want to know if an elementary function has an
elementary antiderivative. If the indefinite Integral returned by this
function is an instance of NonElementaryIntegral, that means that the
Risch algorithm has proven that integral to be non-elementary. Note that
by default, additional methods (such as the Meijer G method outlined
below) are tried on these integrals, as they may be expressible in terms
of special functions, so if you only care about elementary answers, use
risch=True. Also note that an unevaluated Integral returned by this
function is not necessarily a NonElementaryIntegral, even with risch=True,
as it may just be an indication that the particular part of the Risch
algorithm needed to integrate that function is not yet implemented.
Another family of strategies comes from re-writing the integrand in
terms of so-called Meijer G-functions. Indefinite integrals of a
single G-function can always be computed, and the definite integral
of a product of two G-functions can be computed from zero to
infinity. Various strategies are implemented to rewrite integrands
as G-functions, and use this information to compute integrals (see
the ``meijerint`` module).
The option manual=True can be used to use only an algorithm that tries
to mimic integration by hand. This algorithm does not handle as many
integrands as the other algorithms implemented but may return results in
a more familiar form. The ``manualintegrate`` module has functions that
return the steps used (see the module docstring for more information).
In general, the algebraic methods work best for computing
antiderivatives of (possibly complicated) combinations of elementary
functions. The G-function methods work best for computing definite
integrals from zero to infinity of moderately complicated
combinations of special functions, or indefinite integrals of very
simple combinations of special functions.
The strategy employed by the integration code is as follows:
- If computing a definite integral, and both limits are real,
and at least one limit is +- oo, try the G-function method of
definite integration first.
- Try to find an antiderivative, using all available methods, ordered
by performance (that is try fastest method first, slowest last; in
particular polynomial integration is tried first, Meijer
G-functions second to last, and heuristic Risch last).
- If still not successful, try G-functions irrespective of the
limits.
The option meijerg=True, False, None can be used to, respectively:
always use G-function methods and no others, never use G-function
methods, or use all available methods (in order as described above).
It defaults to None.
Examples
========
>>> from sympy import integrate, log, exp, oo
>>> from sympy.abc import a, x, y
>>> integrate(x*y, x)
x**2*y/2
>>> integrate(log(x), x)
x*log(x) - x
>>> integrate(log(x), (x, 1, a))
a*log(a) - a + 1
>>> integrate(x)
x**2/2
Terms that are independent of x are dropped by indefinite integration:
>>> from sympy import sqrt
>>> integrate(sqrt(1 + x), (x, 0, x))
2*(x + 1)**(3/2)/3 - 2/3
>>> integrate(sqrt(1 + x), x)
2*(x + 1)**(3/2)/3
>>> integrate(x*y)
Traceback (most recent call last):
...
ValueError: specify integration variables to integrate x*y
Note that ``integrate(x)`` syntax is meant only for convenience
in interactive sessions and should be avoided in library code.
>>> integrate(x**a*exp(-x), (x, 0, oo)) # same as conds='piecewise'
Piecewise((gamma(a + 1), re(a) > -1),
(Integral(x**a*exp(-x), (x, 0, oo)), True))
>>> integrate(x**a*exp(-x), (x, 0, oo), conds='none')
gamma(a + 1)
>>> integrate(x**a*exp(-x), (x, 0, oo), conds='separate')
(gamma(a + 1), -re(a) < 1)
See Also
========
Integral, Integral.doit
"""
doit_flags = {
'deep': False,
'meijerg': meijerg,
'conds': conds,
'risch': risch,
'heurisch': heurisch,
'manual': manual
}
integral = Integral(*args, **kwargs)
if isinstance(integral, Integral):
return integral.doit(**doit_flags)
else:
new_args = [a.doit(**doit_flags) if isinstance(a, Integral) else a
for a in integral.args]
return integral.func(*new_args)
def line_integrate(field, curve, vars):
"""line_integrate(field, Curve, variables)
Compute the line integral.
Examples
========
>>> from sympy import Curve, line_integrate, E, ln
>>> from sympy.abc import x, y, t
>>> C = Curve([E**t + 1, E**t - 1], (t, 0, ln(2)))
>>> line_integrate(x + y, C, [x, y])
3*sqrt(2)
See Also
========
sympy.integrals.integrals.integrate, Integral
"""
from sympy.geometry import Curve
F = sympify(field)
if not F:
raise ValueError(
"Expecting function specifying field as first argument.")
if not isinstance(curve, Curve):
raise ValueError("Expecting Curve entity as second argument.")
if not is_sequence(vars):
raise ValueError("Expecting ordered iterable for variables.")
if len(curve.functions) != len(vars):
raise ValueError("Field variable size does not match curve dimension.")
if curve.parameter in vars:
raise ValueError("Curve parameter clashes with field parameters.")
# Calculate derivatives for line parameter functions
# F(r) -> F(r(t)) and finally F(r(t)*r'(t))
Ft = F
dldt = 0
for i, var in enumerate(vars):
_f = curve.functions[i]
_dn = diff(_f, curve.parameter)
# ...arc length
dldt = dldt + (_dn * _dn)
Ft = Ft.subs(var, _f)
Ft = Ft * sqrt(dldt)
integral = Integral(Ft, curve.limits).doit(deep=False)
return integral
### Property function dispatching ###
@shape.register(Integral)
def _(expr):
return shape(expr.function)
|
b4d98cf330464ab5e5c6bd7dfd5ccc68f6c54e9664c285507bbc345941ff9fd3 | """Base class for all the objects in SymPy"""
from collections import defaultdict
from collections.abc import Mapping
from itertools import chain, zip_longest
from .assumptions import BasicMeta, ManagedProperties
from .cache import cacheit
from .sympify import _sympify, sympify, SympifyError
from .compatibility import iterable, ordered
from .kind import UndefinedKind
from ._print_helpers import Printable
from inspect import getmro
def as_Basic(expr):
"""Return expr as a Basic instance using strict sympify
or raise a TypeError; this is just a wrapper to _sympify,
raising a TypeError instead of a SympifyError."""
from sympy.utilities.misc import func_name
try:
return _sympify(expr)
except SympifyError:
raise TypeError(
'Argument must be a Basic object, not `%s`' % func_name(
expr))
class Basic(Printable, metaclass=ManagedProperties):
"""
Base class for all SymPy objects.
Notes and conventions
=====================
1) Always use ``.args``, when accessing parameters of some instance:
>>> from sympy import cot
>>> from sympy.abc import x, y
>>> cot(x).args
(x,)
>>> cot(x).args[0]
x
>>> (x*y).args
(x, y)
>>> (x*y).args[1]
y
2) Never use internal methods or variables (the ones prefixed with ``_``):
>>> cot(x)._args # do not use this, use cot(x).args instead
(x,)
3) By "SymPy object" we mean something that can be returned by
``sympify``. But not all objects one encounters using SymPy are
subclasses of Basic. For example, mutable objects are not:
>>> from sympy import Basic, Matrix, sympify
>>> A = Matrix([[1, 2], [3, 4]]).as_mutable()
>>> isinstance(A, Basic)
False
>>> B = sympify(A)
>>> isinstance(B, Basic)
True
"""
__slots__ = ('_mhash', # hash value
'_args', # arguments
'_assumptions'
)
# To be overridden with True in the appropriate subclasses
is_number = False
is_Atom = False
is_Symbol = False
is_symbol = False
is_Indexed = False
is_Dummy = False
is_Wild = False
is_Function = False
is_Add = False
is_Mul = False
is_Pow = False
is_Number = False
is_Float = False
is_Rational = False
is_Integer = False
is_NumberSymbol = False
is_Order = False
is_Derivative = False
is_Piecewise = False
is_Poly = False
is_AlgebraicNumber = False
is_Relational = False
is_Equality = False
is_Boolean = False
is_Not = False
is_Matrix = False
is_Vector = False
is_Point = False
is_MatAdd = False
is_MatMul = False
kind = UndefinedKind
def __new__(cls, *args):
obj = object.__new__(cls)
obj._assumptions = cls.default_assumptions
obj._mhash = None # will be set by __hash__ method.
obj._args = args # all items in args must be Basic objects
return obj
def copy(self):
return self.func(*self.args)
def __getnewargs__(self):
return self.args
def __getstate__(self):
return None
def __reduce_ex__(self, protocol):
if protocol < 2:
msg = "Only pickle protocol 2 or higher is supported by sympy"
raise NotImplementedError(msg)
return super().__reduce_ex__(protocol)
def __hash__(self):
# hash cannot be cached using cache_it because infinite recurrence
# occurs as hash is needed for setting cache dictionary keys
h = self._mhash
if h is None:
h = hash((type(self).__name__,) + self._hashable_content())
self._mhash = h
return h
def _hashable_content(self):
"""Return a tuple of information about self that can be used to
compute the hash. If a class defines additional attributes,
like ``name`` in Symbol, then this method should be updated
accordingly to return such relevant attributes.
Defining more than _hashable_content is necessary if __eq__ has
been defined by a class. See note about this in Basic.__eq__."""
return self._args
@property
def assumptions0(self):
"""
Return object `type` assumptions.
For example:
Symbol('x', real=True)
Symbol('x', integer=True)
are different objects. In other words, besides Python type (Symbol in
this case), the initial assumptions are also forming their typeinfo.
Examples
========
>>> from sympy import Symbol
>>> from sympy.abc import x
>>> x.assumptions0
{'commutative': True}
>>> x = Symbol("x", positive=True)
>>> x.assumptions0
{'commutative': True, 'complex': True, 'extended_negative': False,
'extended_nonnegative': True, 'extended_nonpositive': False,
'extended_nonzero': True, 'extended_positive': True, 'extended_real':
True, 'finite': True, 'hermitian': True, 'imaginary': False,
'infinite': False, 'negative': False, 'nonnegative': True,
'nonpositive': False, 'nonzero': True, 'positive': True, 'real':
True, 'zero': False}
"""
return {}
def compare(self, other):
"""
Return -1, 0, 1 if the object is smaller, equal, or greater than other.
Not in the mathematical sense. If the object is of a different type
from the "other" then their classes are ordered according to
the sorted_classes list.
Examples
========
>>> from sympy.abc import x, y
>>> x.compare(y)
-1
>>> x.compare(x)
0
>>> y.compare(x)
1
"""
# all redefinitions of __cmp__ method should start with the
# following lines:
if self is other:
return 0
n1 = self.__class__
n2 = other.__class__
c = (n1 > n2) - (n1 < n2)
if c:
return c
#
st = self._hashable_content()
ot = other._hashable_content()
c = (len(st) > len(ot)) - (len(st) < len(ot))
if c:
return c
for l, r in zip(st, ot):
l = Basic(*l) if isinstance(l, frozenset) else l
r = Basic(*r) if isinstance(r, frozenset) else r
if isinstance(l, Basic):
c = l.compare(r)
else:
c = (l > r) - (l < r)
if c:
return c
return 0
@staticmethod
def _compare_pretty(a, b):
from sympy.series.order import Order
if isinstance(a, Order) and not isinstance(b, Order):
return 1
if not isinstance(a, Order) and isinstance(b, Order):
return -1
if a.is_Rational and b.is_Rational:
l = a.p * b.q
r = b.p * a.q
return (l > r) - (l < r)
else:
from sympy.core.symbol import Wild
p1, p2, p3 = Wild("p1"), Wild("p2"), Wild("p3")
r_a = a.match(p1 * p2**p3)
if r_a and p3 in r_a:
a3 = r_a[p3]
r_b = b.match(p1 * p2**p3)
if r_b and p3 in r_b:
b3 = r_b[p3]
c = Basic.compare(a3, b3)
if c != 0:
return c
return Basic.compare(a, b)
@classmethod
def fromiter(cls, args, **assumptions):
"""
Create a new object from an iterable.
This is a convenience function that allows one to create objects from
any iterable, without having to convert to a list or tuple first.
Examples
========
>>> from sympy import Tuple
>>> Tuple.fromiter(i for i in range(5))
(0, 1, 2, 3, 4)
"""
return cls(*tuple(args), **assumptions)
@classmethod
def class_key(cls):
"""Nice order of classes. """
return 5, 0, cls.__name__
@cacheit
def sort_key(self, order=None):
"""
Return a sort key.
Examples
========
>>> from sympy.core import S, I
>>> sorted([S(1)/2, I, -I], key=lambda x: x.sort_key())
[1/2, -I, I]
>>> S("[x, 1/x, 1/x**2, x**2, x**(1/2), x**(1/4), x**(3/2)]")
[x, 1/x, x**(-2), x**2, sqrt(x), x**(1/4), x**(3/2)]
>>> sorted(_, key=lambda x: x.sort_key())
[x**(-2), 1/x, x**(1/4), sqrt(x), x, x**(3/2), x**2]
"""
# XXX: remove this when issue 5169 is fixed
def inner_key(arg):
if isinstance(arg, Basic):
return arg.sort_key(order)
else:
return arg
args = self._sorted_args
args = len(args), tuple([inner_key(arg) for arg in args])
return self.class_key(), args, S.One.sort_key(), S.One
def __eq__(self, other):
"""Return a boolean indicating whether a == b on the basis of
their symbolic trees.
This is the same as a.compare(b) == 0 but faster.
Notes
=====
If a class that overrides __eq__() needs to retain the
implementation of __hash__() from a parent class, the
interpreter must be told this explicitly by setting __hash__ =
<ParentClass>.__hash__. Otherwise the inheritance of __hash__()
will be blocked, just as if __hash__ had been explicitly set to
None.
References
==========
from http://docs.python.org/dev/reference/datamodel.html#object.__hash__
"""
if self is other:
return True
tself = type(self)
tother = type(other)
if tself is not tother:
try:
other = _sympify(other)
tother = type(other)
except SympifyError:
return NotImplemented
# As long as we have the ordering of classes (sympy.core),
# comparing types will be slow in Python 2, because it uses
# __cmp__. Until we can remove it
# (https://github.com/sympy/sympy/issues/4269), we only compare
# types in Python 2 directly if they actually have __ne__.
if type(tself).__ne__ is not type.__ne__:
if tself != tother:
return False
elif tself is not tother:
return False
return self._hashable_content() == other._hashable_content()
def __ne__(self, other):
"""``a != b`` -> Compare two symbolic trees and see whether they are different
this is the same as:
``a.compare(b) != 0``
but faster
"""
return not self == other
def dummy_eq(self, other, symbol=None):
"""
Compare two expressions and handle dummy symbols.
Examples
========
>>> from sympy import Dummy
>>> from sympy.abc import x, y
>>> u = Dummy('u')
>>> (u**2 + 1).dummy_eq(x**2 + 1)
True
>>> (u**2 + 1) == (x**2 + 1)
False
>>> (u**2 + y).dummy_eq(x**2 + y, x)
True
>>> (u**2 + y).dummy_eq(x**2 + y, y)
False
"""
s = self.as_dummy()
o = _sympify(other)
o = o.as_dummy()
dummy_symbols = [i for i in s.free_symbols if i.is_Dummy]
if len(dummy_symbols) == 1:
dummy = dummy_symbols.pop()
else:
return s == o
if symbol is None:
symbols = o.free_symbols
if len(symbols) == 1:
symbol = symbols.pop()
else:
return s == o
tmp = dummy.__class__()
return s.xreplace({dummy: tmp}) == o.xreplace({symbol: tmp})
def atoms(self, *types):
"""Returns the atoms that form the current object.
By default, only objects that are truly atomic and can't
be divided into smaller pieces are returned: symbols, numbers,
and number symbols like I and pi. It is possible to request
atoms of any type, however, as demonstrated below.
Examples
========
>>> from sympy import I, pi, sin
>>> from sympy.abc import x, y
>>> (1 + x + 2*sin(y + I*pi)).atoms()
{1, 2, I, pi, x, y}
If one or more types are given, the results will contain only
those types of atoms.
>>> from sympy import Number, NumberSymbol, Symbol
>>> (1 + x + 2*sin(y + I*pi)).atoms(Symbol)
{x, y}
>>> (1 + x + 2*sin(y + I*pi)).atoms(Number)
{1, 2}
>>> (1 + x + 2*sin(y + I*pi)).atoms(Number, NumberSymbol)
{1, 2, pi}
>>> (1 + x + 2*sin(y + I*pi)).atoms(Number, NumberSymbol, I)
{1, 2, I, pi}
Note that I (imaginary unit) and zoo (complex infinity) are special
types of number symbols and are not part of the NumberSymbol class.
The type can be given implicitly, too:
>>> (1 + x + 2*sin(y + I*pi)).atoms(x) # x is a Symbol
{x, y}
Be careful to check your assumptions when using the implicit option
since ``S(1).is_Integer = True`` but ``type(S(1))`` is ``One``, a special type
of sympy atom, while ``type(S(2))`` is type ``Integer`` and will find all
integers in an expression:
>>> from sympy import S
>>> (1 + x + 2*sin(y + I*pi)).atoms(S(1))
{1}
>>> (1 + x + 2*sin(y + I*pi)).atoms(S(2))
{1, 2}
Finally, arguments to atoms() can select more than atomic atoms: any
sympy type (loaded in core/__init__.py) can be listed as an argument
and those types of "atoms" as found in scanning the arguments of the
expression recursively:
>>> from sympy import Function, Mul
>>> from sympy.core.function import AppliedUndef
>>> f = Function('f')
>>> (1 + f(x) + 2*sin(y + I*pi)).atoms(Function)
{f(x), sin(y + I*pi)}
>>> (1 + f(x) + 2*sin(y + I*pi)).atoms(AppliedUndef)
{f(x)}
>>> (1 + x + 2*sin(y + I*pi)).atoms(Mul)
{I*pi, 2*sin(y + I*pi)}
"""
if types:
types = tuple(
[t if isinstance(t, type) else type(t) for t in types])
nodes = preorder_traversal(self)
if types:
result = {node for node in nodes if isinstance(node, types)}
else:
result = {node for node in nodes if not node.args}
return result
@property
def free_symbols(self):
"""Return from the atoms of self those which are free symbols.
For most expressions, all symbols are free symbols. For some classes
this is not true. e.g. Integrals use Symbols for the dummy variables
which are bound variables, so Integral has a method to return all
symbols except those. Derivative keeps track of symbols with respect
to which it will perform a derivative; those are
bound variables, too, so it has its own free_symbols method.
Any other method that uses bound variables should implement a
free_symbols method."""
return set().union(*[a.free_symbols for a in self.args])
@property
def expr_free_symbols(self):
from sympy.utilities.exceptions import SymPyDeprecationWarning
SymPyDeprecationWarning(feature="expr_free_symbols method",
issue=21494,
deprecated_since_version="1.9").warn()
return set()
def as_dummy(self):
"""Return the expression with any objects having structurally
bound symbols replaced with unique, canonical symbols within
the object in which they appear and having only the default
assumption for commutativity being True. When applied to a
symbol a new symbol having only the same commutativity will be
returned.
Examples
========
>>> from sympy import Integral, Symbol
>>> from sympy.abc import x
>>> r = Symbol('r', real=True)
>>> Integral(r, (r, x)).as_dummy()
Integral(_0, (_0, x))
>>> _.variables[0].is_real is None
True
>>> r.as_dummy()
_r
Notes
=====
Any object that has structurally bound variables should have
a property, `bound_symbols` that returns those symbols
appearing in the object.
"""
from sympy.core.symbol import Dummy, Symbol
def can(x):
# mask free that shadow bound
free = x.free_symbols
bound = set(x.bound_symbols)
d = {i: Dummy() for i in bound & free}
x = x.subs(d)
# replace bound with canonical names
x = x.xreplace(x.canonical_variables)
# return after undoing masking
return x.xreplace({v: k for k, v in d.items()})
if not self.has(Symbol):
return self
return self.replace(
lambda x: hasattr(x, 'bound_symbols'),
lambda x: can(x),
simultaneous=False)
@property
def canonical_variables(self):
"""Return a dictionary mapping any variable defined in
``self.bound_symbols`` to Symbols that do not clash
with any free symbols in the expression.
Examples
========
>>> from sympy import Lambda
>>> from sympy.abc import x
>>> Lambda(x, 2*x).canonical_variables
{x: _0}
"""
from sympy.utilities.iterables import numbered_symbols
if not hasattr(self, 'bound_symbols'):
return {}
dums = numbered_symbols('_')
reps = {}
# watch out for free symbol that are not in bound symbols;
# those that are in bound symbols are about to get changed
bound = self.bound_symbols
names = {i.name for i in self.free_symbols - set(bound)}
for b in bound:
d = next(dums)
if b.is_Symbol:
while d.name in names:
d = next(dums)
reps[b] = d
return reps
def rcall(self, *args):
"""Apply on the argument recursively through the expression tree.
This method is used to simulate a common abuse of notation for
operators. For instance in SymPy the the following will not work:
``(x+Lambda(y, 2*y))(z) == x+2*z``,
however you can use
>>> from sympy import Lambda
>>> from sympy.abc import x, y, z
>>> (x + Lambda(y, 2*y)).rcall(z)
x + 2*z
"""
return Basic._recursive_call(self, args)
@staticmethod
def _recursive_call(expr_to_call, on_args):
"""Helper for rcall method."""
from sympy import Symbol
def the_call_method_is_overridden(expr):
for cls in getmro(type(expr)):
if '__call__' in cls.__dict__:
return cls != Basic
if callable(expr_to_call) and the_call_method_is_overridden(expr_to_call):
if isinstance(expr_to_call, Symbol): # XXX When you call a Symbol it is
return expr_to_call # transformed into an UndefFunction
else:
return expr_to_call(*on_args)
elif expr_to_call.args:
args = [Basic._recursive_call(
sub, on_args) for sub in expr_to_call.args]
return type(expr_to_call)(*args)
else:
return expr_to_call
def is_hypergeometric(self, k):
from sympy.simplify import hypersimp
from sympy.functions import Piecewise
if self.has(Piecewise):
return None
return hypersimp(self, k) is not None
@property
def is_comparable(self):
"""Return True if self can be computed to a real number
(or already is a real number) with precision, else False.
Examples
========
>>> from sympy import exp_polar, pi, I
>>> (I*exp_polar(I*pi/2)).is_comparable
True
>>> (I*exp_polar(I*pi*2)).is_comparable
False
A False result does not mean that `self` cannot be rewritten
into a form that would be comparable. For example, the
difference computed below is zero but without simplification
it does not evaluate to a zero with precision:
>>> e = 2**pi*(1 + 2**pi)
>>> dif = e - e.expand()
>>> dif.is_comparable
False
>>> dif.n(2)._prec
1
"""
is_extended_real = self.is_extended_real
if is_extended_real is False:
return False
if not self.is_number:
return False
# don't re-eval numbers that are already evaluated since
# this will create spurious precision
n, i = [p.evalf(2) if not p.is_Number else p
for p in self.as_real_imag()]
if not (i.is_Number and n.is_Number):
return False
if i:
# if _prec = 1 we can't decide and if not,
# the answer is False because numbers with
# imaginary parts can't be compared
# so return False
return False
else:
return n._prec != 1
@property
def func(self):
"""
The top-level function in an expression.
The following should hold for all objects::
>> x == x.func(*x.args)
Examples
========
>>> from sympy.abc import x
>>> a = 2*x
>>> a.func
<class 'sympy.core.mul.Mul'>
>>> a.args
(2, x)
>>> a.func(*a.args)
2*x
>>> a == a.func(*a.args)
True
"""
return self.__class__
@property
def args(self):
"""Returns a tuple of arguments of 'self'.
Examples
========
>>> from sympy import cot
>>> from sympy.abc import x, y
>>> cot(x).args
(x,)
>>> cot(x).args[0]
x
>>> (x*y).args
(x, y)
>>> (x*y).args[1]
y
Notes
=====
Never use self._args, always use self.args.
Only use _args in __new__ when creating a new function.
Don't override .args() from Basic (so that it's easy to
change the interface in the future if needed).
"""
return self._args
@property
def _sorted_args(self):
"""
The same as ``args``. Derived classes which don't fix an
order on their arguments should override this method to
produce the sorted representation.
"""
return self.args
def as_content_primitive(self, radical=False, clear=True):
"""A stub to allow Basic args (like Tuple) to be skipped when computing
the content and primitive components of an expression.
See Also
========
sympy.core.expr.Expr.as_content_primitive
"""
return S.One, self
def subs(self, *args, **kwargs):
"""
Substitutes old for new in an expression after sympifying args.
`args` is either:
- two arguments, e.g. foo.subs(old, new)
- one iterable argument, e.g. foo.subs(iterable). The iterable may be
o an iterable container with (old, new) pairs. In this case the
replacements are processed in the order given with successive
patterns possibly affecting replacements already made.
o a dict or set whose key/value items correspond to old/new pairs.
In this case the old/new pairs will be sorted by op count and in
case of a tie, by number of args and the default_sort_key. The
resulting sorted list is then processed as an iterable container
(see previous).
If the keyword ``simultaneous`` is True, the subexpressions will not be
evaluated until all the substitutions have been made.
Examples
========
>>> from sympy import pi, exp, limit, oo
>>> from sympy.abc import x, y
>>> (1 + x*y).subs(x, pi)
pi*y + 1
>>> (1 + x*y).subs({x:pi, y:2})
1 + 2*pi
>>> (1 + x*y).subs([(x, pi), (y, 2)])
1 + 2*pi
>>> reps = [(y, x**2), (x, 2)]
>>> (x + y).subs(reps)
6
>>> (x + y).subs(reversed(reps))
x**2 + 2
>>> (x**2 + x**4).subs(x**2, y)
y**2 + y
To replace only the x**2 but not the x**4, use xreplace:
>>> (x**2 + x**4).xreplace({x**2: y})
x**4 + y
To delay evaluation until all substitutions have been made,
set the keyword ``simultaneous`` to True:
>>> (x/y).subs([(x, 0), (y, 0)])
0
>>> (x/y).subs([(x, 0), (y, 0)], simultaneous=True)
nan
This has the added feature of not allowing subsequent substitutions
to affect those already made:
>>> ((x + y)/y).subs({x + y: y, y: x + y})
1
>>> ((x + y)/y).subs({x + y: y, y: x + y}, simultaneous=True)
y/(x + y)
In order to obtain a canonical result, unordered iterables are
sorted by count_op length, number of arguments and by the
default_sort_key to break any ties. All other iterables are left
unsorted.
>>> from sympy import sqrt, sin, cos
>>> from sympy.abc import a, b, c, d, e
>>> A = (sqrt(sin(2*x)), a)
>>> B = (sin(2*x), b)
>>> C = (cos(2*x), c)
>>> D = (x, d)
>>> E = (exp(x), e)
>>> expr = sqrt(sin(2*x))*sin(exp(x)*x)*cos(2*x) + sin(2*x)
>>> expr.subs(dict([A, B, C, D, E]))
a*c*sin(d*e) + b
The resulting expression represents a literal replacement of the
old arguments with the new arguments. This may not reflect the
limiting behavior of the expression:
>>> (x**3 - 3*x).subs({x: oo})
nan
>>> limit(x**3 - 3*x, x, oo)
oo
If the substitution will be followed by numerical
evaluation, it is better to pass the substitution to
evalf as
>>> (1/x).evalf(subs={x: 3.0}, n=21)
0.333333333333333333333
rather than
>>> (1/x).subs({x: 3.0}).evalf(21)
0.333333333333333314830
as the former will ensure that the desired level of precision is
obtained.
See Also
========
replace: replacement capable of doing wildcard-like matching,
parsing of match, and conditional replacements
xreplace: exact node replacement in expr tree; also capable of
using matching rules
sympy.core.evalf.EvalfMixin.evalf: calculates the given formula to a desired level of precision
"""
from sympy.core.compatibility import _nodes, default_sort_key
from sympy.core.containers import Dict
from sympy.core.symbol import Dummy, Symbol
from sympy.utilities.misc import filldedent
unordered = False
if len(args) == 1:
sequence = args[0]
if isinstance(sequence, set):
unordered = True
elif isinstance(sequence, (Dict, Mapping)):
unordered = True
sequence = sequence.items()
elif not iterable(sequence):
raise ValueError(filldedent("""
When a single argument is passed to subs
it should be a dictionary of old: new pairs or an iterable
of (old, new) tuples."""))
elif len(args) == 2:
sequence = [args]
else:
raise ValueError("subs accepts either 1 or 2 arguments")
sequence = list(sequence)
for i, s in enumerate(sequence):
if isinstance(s[0], str):
# when old is a string we prefer Symbol
s = Symbol(s[0]), s[1]
try:
s = [sympify(_, strict=not isinstance(_, (str, type)))
for _ in s]
except SympifyError:
# if it can't be sympified, skip it
sequence[i] = None
continue
# skip if there is no change
sequence[i] = None if _aresame(*s) else tuple(s)
sequence = list(filter(None, sequence))
if unordered:
sequence = dict(sequence)
# order so more complex items are first and items
# of identical complexity are ordered so
# f(x) < f(y) < x < y
# \___ 2 __/ \_1_/ <- number of nodes
#
# For more complex ordering use an unordered sequence.
k = list(ordered(sequence, default=False, keys=(
lambda x: -_nodes(x),
lambda x: default_sort_key(x),
)))
sequence = [(k, sequence[k]) for k in k]
if kwargs.pop('simultaneous', False): # XXX should this be the default for dict subs?
reps = {}
rv = self
kwargs['hack2'] = True
m = Dummy('subs_m')
for old, new in sequence:
com = new.is_commutative
if com is None:
com = True
d = Dummy('subs_d', commutative=com)
# using d*m so Subs will be used on dummy variables
# in things like Derivative(f(x, y), x) in which x
# is both free and bound
rv = rv._subs(old, d*m, **kwargs)
if not isinstance(rv, Basic):
break
reps[d] = new
reps[m] = S.One # get rid of m
return rv.xreplace(reps)
else:
rv = self
for old, new in sequence:
rv = rv._subs(old, new, **kwargs)
if not isinstance(rv, Basic):
break
return rv
@cacheit
def _subs(self, old, new, **hints):
"""Substitutes an expression old -> new.
If self is not equal to old then _eval_subs is called.
If _eval_subs doesn't want to make any special replacement
then a None is received which indicates that the fallback
should be applied wherein a search for replacements is made
amongst the arguments of self.
>>> from sympy import Add
>>> from sympy.abc import x, y, z
Examples
========
Add's _eval_subs knows how to target x + y in the following
so it makes the change:
>>> (x + y + z).subs(x + y, 1)
z + 1
Add's _eval_subs doesn't need to know how to find x + y in
the following:
>>> Add._eval_subs(z*(x + y) + 3, x + y, 1) is None
True
The returned None will cause the fallback routine to traverse the args and
pass the z*(x + y) arg to Mul where the change will take place and the
substitution will succeed:
>>> (z*(x + y) + 3).subs(x + y, 1)
z + 3
** Developers Notes **
An _eval_subs routine for a class should be written if:
1) any arguments are not instances of Basic (e.g. bool, tuple);
2) some arguments should not be targeted (as in integration
variables);
3) if there is something other than a literal replacement
that should be attempted (as in Piecewise where the condition
may be updated without doing a replacement).
If it is overridden, here are some special cases that might arise:
1) If it turns out that no special change was made and all
the original sub-arguments should be checked for
replacements then None should be returned.
2) If it is necessary to do substitutions on a portion of
the expression then _subs should be called. _subs will
handle the case of any sub-expression being equal to old
(which usually would not be the case) while its fallback
will handle the recursion into the sub-arguments. For
example, after Add's _eval_subs removes some matching terms
it must process the remaining terms so it calls _subs
on each of the un-matched terms and then adds them
onto the terms previously obtained.
3) If the initial expression should remain unchanged then
the original expression should be returned. (Whenever an
expression is returned, modified or not, no further
substitution of old -> new is attempted.) Sum's _eval_subs
routine uses this strategy when a substitution is attempted
on any of its summation variables.
"""
def fallback(self, old, new):
"""
Try to replace old with new in any of self's arguments.
"""
hit = False
args = list(self.args)
for i, arg in enumerate(args):
if not hasattr(arg, '_eval_subs'):
continue
arg = arg._subs(old, new, **hints)
if not _aresame(arg, args[i]):
hit = True
args[i] = arg
if hit:
rv = self.func(*args)
hack2 = hints.get('hack2', False)
if hack2 and self.is_Mul and not rv.is_Mul: # 2-arg hack
coeff = S.One
nonnumber = []
for i in args:
if i.is_Number:
coeff *= i
else:
nonnumber.append(i)
nonnumber = self.func(*nonnumber)
if coeff is S.One:
return nonnumber
else:
return self.func(coeff, nonnumber, evaluate=False)
return rv
return self
if _aresame(self, old):
return new
rv = self._eval_subs(old, new)
if rv is None:
rv = fallback(self, old, new)
return rv
def _eval_subs(self, old, new):
"""Override this stub if you want to do anything more than
attempt a replacement of old with new in the arguments of self.
See also
========
_subs
"""
return None
def xreplace(self, rule):
"""
Replace occurrences of objects within the expression.
Parameters
==========
rule : dict-like
Expresses a replacement rule
Returns
=======
xreplace : the result of the replacement
Examples
========
>>> from sympy import symbols, pi, exp
>>> x, y, z = symbols('x y z')
>>> (1 + x*y).xreplace({x: pi})
pi*y + 1
>>> (1 + x*y).xreplace({x: pi, y: 2})
1 + 2*pi
Replacements occur only if an entire node in the expression tree is
matched:
>>> (x*y + z).xreplace({x*y: pi})
z + pi
>>> (x*y*z).xreplace({x*y: pi})
x*y*z
>>> (2*x).xreplace({2*x: y, x: z})
y
>>> (2*2*x).xreplace({2*x: y, x: z})
4*z
>>> (x + y + 2).xreplace({x + y: 2})
x + y + 2
>>> (x + 2 + exp(x + 2)).xreplace({x + 2: y})
x + exp(y) + 2
xreplace doesn't differentiate between free and bound symbols. In the
following, subs(x, y) would not change x since it is a bound symbol,
but xreplace does:
>>> from sympy import Integral
>>> Integral(x, (x, 1, 2*x)).xreplace({x: y})
Integral(y, (y, 1, 2*y))
Trying to replace x with an expression raises an error:
>>> Integral(x, (x, 1, 2*x)).xreplace({x: 2*y}) # doctest: +SKIP
ValueError: Invalid limits given: ((2*y, 1, 4*y),)
See Also
========
replace: replacement capable of doing wildcard-like matching,
parsing of match, and conditional replacements
subs: substitution of subexpressions as defined by the objects
themselves.
"""
value, _ = self._xreplace(rule)
return value
def _xreplace(self, rule):
"""
Helper for xreplace. Tracks whether a replacement actually occurred.
"""
if self in rule:
return rule[self], True
elif rule:
args = []
changed = False
for a in self.args:
_xreplace = getattr(a, '_xreplace', None)
if _xreplace is not None:
a_xr = _xreplace(rule)
args.append(a_xr[0])
changed |= a_xr[1]
else:
args.append(a)
args = tuple(args)
if changed:
return self.func(*args), True
return self, False
@cacheit
def has(self, *patterns):
"""
Test whether any subexpression matches any of the patterns.
Examples
========
>>> from sympy import sin
>>> from sympy.abc import x, y, z
>>> (x**2 + sin(x*y)).has(z)
False
>>> (x**2 + sin(x*y)).has(x, y, z)
True
>>> x.has(x)
True
Note ``has`` is a structural algorithm with no knowledge of
mathematics. Consider the following half-open interval:
>>> from sympy.sets import Interval
>>> i = Interval.Lopen(0, 5); i
Interval.Lopen(0, 5)
>>> i.args
(0, 5, True, False)
>>> i.has(4) # there is no "4" in the arguments
False
>>> i.has(0) # there *is* a "0" in the arguments
True
Instead, use ``contains`` to determine whether a number is in the
interval or not:
>>> i.contains(4)
True
>>> i.contains(0)
False
Note that ``expr.has(*patterns)`` is exactly equivalent to
``any(expr.has(p) for p in patterns)``. In particular, ``False`` is
returned when the list of patterns is empty.
>>> x.has()
False
"""
return any(self._has(pattern) for pattern in patterns)
def _has(self, pattern):
"""Helper for .has()"""
from sympy.core.function import UndefinedFunction, Function
if isinstance(pattern, UndefinedFunction):
return any(f.func == pattern or f == pattern
for f in self.atoms(Function, UndefinedFunction))
if isinstance(pattern, BasicMeta):
subtrees = preorder_traversal(self)
return any(isinstance(arg, pattern) for arg in subtrees)
pattern = _sympify(pattern)
_has_matcher = getattr(pattern, '_has_matcher', None)
if _has_matcher is not None:
match = _has_matcher()
return any(match(arg) for arg in preorder_traversal(self))
else:
return any(arg == pattern for arg in preorder_traversal(self))
def _has_matcher(self):
"""Helper for .has()"""
return lambda other: self == other
def replace(self, query, value, map=False, simultaneous=True, exact=None):
"""
Replace matching subexpressions of ``self`` with ``value``.
If ``map = True`` then also return the mapping {old: new} where ``old``
was a sub-expression found with query and ``new`` is the replacement
value for it. If the expression itself doesn't match the query, then
the returned value will be ``self.xreplace(map)`` otherwise it should
be ``self.subs(ordered(map.items()))``.
Traverses an expression tree and performs replacement of matching
subexpressions from the bottom to the top of the tree. The default
approach is to do the replacement in a simultaneous fashion so
changes made are targeted only once. If this is not desired or causes
problems, ``simultaneous`` can be set to False.
In addition, if an expression containing more than one Wild symbol
is being used to match subexpressions and the ``exact`` flag is None
it will be set to True so the match will only succeed if all non-zero
values are received for each Wild that appears in the match pattern.
Setting this to False accepts a match of 0; while setting it True
accepts all matches that have a 0 in them. See example below for
cautions.
The list of possible combinations of queries and replacement values
is listed below:
Examples
========
Initial setup
>>> from sympy import log, sin, cos, tan, Wild, Mul, Add
>>> from sympy.abc import x, y
>>> f = log(sin(x)) + tan(sin(x**2))
1.1. type -> type
obj.replace(type, newtype)
When object of type ``type`` is found, replace it with the
result of passing its argument(s) to ``newtype``.
>>> f.replace(sin, cos)
log(cos(x)) + tan(cos(x**2))
>>> sin(x).replace(sin, cos, map=True)
(cos(x), {sin(x): cos(x)})
>>> (x*y).replace(Mul, Add)
x + y
1.2. type -> func
obj.replace(type, func)
When object of type ``type`` is found, apply ``func`` to its
argument(s). ``func`` must be written to handle the number
of arguments of ``type``.
>>> f.replace(sin, lambda arg: sin(2*arg))
log(sin(2*x)) + tan(sin(2*x**2))
>>> (x*y).replace(Mul, lambda *args: sin(2*Mul(*args)))
sin(2*x*y)
2.1. pattern -> expr
obj.replace(pattern(wild), expr(wild))
Replace subexpressions matching ``pattern`` with the expression
written in terms of the Wild symbols in ``pattern``.
>>> a, b = map(Wild, 'ab')
>>> f.replace(sin(a), tan(a))
log(tan(x)) + tan(tan(x**2))
>>> f.replace(sin(a), tan(a/2))
log(tan(x/2)) + tan(tan(x**2/2))
>>> f.replace(sin(a), a)
log(x) + tan(x**2)
>>> (x*y).replace(a*x, a)
y
Matching is exact by default when more than one Wild symbol
is used: matching fails unless the match gives non-zero
values for all Wild symbols:
>>> (2*x + y).replace(a*x + b, b - a)
y - 2
>>> (2*x).replace(a*x + b, b - a)
2*x
When set to False, the results may be non-intuitive:
>>> (2*x).replace(a*x + b, b - a, exact=False)
2/x
2.2. pattern -> func
obj.replace(pattern(wild), lambda wild: expr(wild))
All behavior is the same as in 2.1 but now a function in terms of
pattern variables is used rather than an expression:
>>> f.replace(sin(a), lambda a: sin(2*a))
log(sin(2*x)) + tan(sin(2*x**2))
3.1. func -> func
obj.replace(filter, func)
Replace subexpression ``e`` with ``func(e)`` if ``filter(e)``
is True.
>>> g = 2*sin(x**3)
>>> g.replace(lambda expr: expr.is_Number, lambda expr: expr**2)
4*sin(x**9)
The expression itself is also targeted by the query but is done in
such a fashion that changes are not made twice.
>>> e = x*(x*y + 1)
>>> e.replace(lambda x: x.is_Mul, lambda x: 2*x)
2*x*(2*x*y + 1)
When matching a single symbol, `exact` will default to True, but
this may or may not be the behavior that is desired:
Here, we want `exact=False`:
>>> from sympy import Function
>>> f = Function('f')
>>> e = f(1) + f(0)
>>> q = f(a), lambda a: f(a + 1)
>>> e.replace(*q, exact=False)
f(1) + f(2)
>>> e.replace(*q, exact=True)
f(0) + f(2)
But here, the nature of matching makes selecting
the right setting tricky:
>>> e = x**(1 + y)
>>> (x**(1 + y)).replace(x**(1 + a), lambda a: x**-a, exact=False)
x
>>> (x**(1 + y)).replace(x**(1 + a), lambda a: x**-a, exact=True)
x**(-x - y + 1)
>>> (x**y).replace(x**(1 + a), lambda a: x**-a, exact=False)
x
>>> (x**y).replace(x**(1 + a), lambda a: x**-a, exact=True)
x**(1 - y)
It is probably better to use a different form of the query
that describes the target expression more precisely:
>>> (1 + x**(1 + y)).replace(
... lambda x: x.is_Pow and x.exp.is_Add and x.exp.args[0] == 1,
... lambda x: x.base**(1 - (x.exp - 1)))
...
x**(1 - y) + 1
See Also
========
subs: substitution of subexpressions as defined by the objects
themselves.
xreplace: exact node replacement in expr tree; also capable of
using matching rules
"""
from sympy.core.symbol import Wild
try:
query = _sympify(query)
except SympifyError:
pass
try:
value = _sympify(value)
except SympifyError:
pass
if isinstance(query, type):
_query = lambda expr: isinstance(expr, query)
if isinstance(value, type):
_value = lambda expr, result: value(*expr.args)
elif callable(value):
_value = lambda expr, result: value(*expr.args)
else:
raise TypeError(
"given a type, replace() expects another "
"type or a callable")
elif isinstance(query, Basic):
_query = lambda expr: expr.match(query)
if exact is None:
exact = (len(query.atoms(Wild)) > 1)
if isinstance(value, Basic):
if exact:
_value = lambda expr, result: (value.subs(result)
if all(result.values()) else expr)
else:
_value = lambda expr, result: value.subs(result)
elif callable(value):
# match dictionary keys get the trailing underscore stripped
# from them and are then passed as keywords to the callable;
# if ``exact`` is True, only accept match if there are no null
# values amongst those matched.
if exact:
_value = lambda expr, result: (value(**
{str(k)[:-1]: v for k, v in result.items()})
if all(val for val in result.values()) else expr)
else:
_value = lambda expr, result: value(**
{str(k)[:-1]: v for k, v in result.items()})
else:
raise TypeError(
"given an expression, replace() expects "
"another expression or a callable")
elif callable(query):
_query = query
if callable(value):
_value = lambda expr, result: value(expr)
else:
raise TypeError(
"given a callable, replace() expects "
"another callable")
else:
raise TypeError(
"first argument to replace() must be a "
"type, an expression or a callable")
def walk(rv, F):
"""Apply ``F`` to args and then to result.
"""
args = getattr(rv, 'args', None)
if args is not None:
if args:
newargs = tuple([walk(a, F) for a in args])
if args != newargs:
rv = rv.func(*newargs)
if simultaneous:
# if rv is something that was already
# matched (that was changed) then skip
# applying F again
for i, e in enumerate(args):
if rv == e and e != newargs[i]:
return rv
rv = F(rv)
return rv
mapping = {} # changes that took place
def rec_replace(expr):
result = _query(expr)
if result or result == {}:
v = _value(expr, result)
if v is not None and v != expr:
if map:
mapping[expr] = v
expr = v
return expr
rv = walk(self, rec_replace)
return (rv, mapping) if map else rv
def find(self, query, group=False):
"""Find all subexpressions matching a query. """
query = _make_find_query(query)
results = list(filter(query, preorder_traversal(self)))
if not group:
return set(results)
else:
groups = {}
for result in results:
if result in groups:
groups[result] += 1
else:
groups[result] = 1
return groups
def count(self, query):
"""Count the number of matching subexpressions. """
query = _make_find_query(query)
return sum(bool(query(sub)) for sub in preorder_traversal(self))
def matches(self, expr, repl_dict={}, old=False):
"""
Helper method for match() that looks for a match between Wild symbols
in self and expressions in expr.
Examples
========
>>> from sympy import symbols, Wild, Basic
>>> a, b, c = symbols('a b c')
>>> x = Wild('x')
>>> Basic(a + x, x).matches(Basic(a + b, c)) is None
True
>>> Basic(a + x, x).matches(Basic(a + b + c, b + c))
{x_: b + c}
"""
repl_dict = repl_dict.copy()
expr = sympify(expr)
if not isinstance(expr, self.__class__):
return None
if self == expr:
return repl_dict
if len(self.args) != len(expr.args):
return None
d = repl_dict.copy()
for arg, other_arg in zip(self.args, expr.args):
if arg == other_arg:
continue
d = arg.xreplace(d).matches(other_arg, d, old=old)
if d is None:
return None
return d
def match(self, pattern, old=False):
"""
Pattern matching.
Wild symbols match all.
Return ``None`` when expression (self) does not match
with pattern. Otherwise return a dictionary such that::
pattern.xreplace(self.match(pattern)) == self
Examples
========
>>> from sympy import Wild, Sum
>>> from sympy.abc import x, y
>>> p = Wild("p")
>>> q = Wild("q")
>>> r = Wild("r")
>>> e = (x+y)**(x+y)
>>> e.match(p**p)
{p_: x + y}
>>> e.match(p**q)
{p_: x + y, q_: x + y}
>>> e = (2*x)**2
>>> e.match(p*q**r)
{p_: 4, q_: x, r_: 2}
>>> (p*q**r).xreplace(e.match(p*q**r))
4*x**2
Structurally bound symbols are ignored during matching:
>>> Sum(x, (x, 1, 2)).match(Sum(y, (y, 1, p)))
{p_: 2}
But they can be identified if desired:
>>> Sum(x, (x, 1, 2)).match(Sum(q, (q, 1, p)))
{p_: 2, q_: x}
The ``old`` flag will give the old-style pattern matching where
expressions and patterns are essentially solved to give the
match. Both of the following give None unless ``old=True``:
>>> (x - 2).match(p - x, old=True)
{p_: 2*x - 2}
>>> (2/x).match(p*x, old=True)
{p_: 2/x**2}
"""
from sympy.core.symbol import Wild
from sympy.core.function import WildFunction
from sympy.utilities.misc import filldedent
pattern = sympify(pattern)
# match non-bound symbols
canonical = lambda x: x if x.is_Symbol else x.as_dummy()
m = canonical(pattern).matches(canonical(self), old=old)
if m is None:
return m
wild = pattern.atoms(Wild, WildFunction)
# sanity check
if set(m) - wild:
raise ValueError(filldedent('''
Some `matches` routine did not use a copy of repl_dict
and injected unexpected symbols. Report this as an
error at https://github.com/sympy/sympy/issues'''))
# now see if bound symbols were requested
bwild = wild - set(m)
if not bwild:
return m
# replace free-Wild symbols in pattern with match result
# so they will match but not be in the next match
wpat = pattern.xreplace(m)
# identify remaining bound wild
w = wpat.matches(self, old=old)
# add them to m
if w:
m.update(w)
# done
return m
def count_ops(self, visual=None):
"""wrapper for count_ops that returns the operation count."""
from sympy import count_ops
return count_ops(self, visual)
def doit(self, **hints):
"""Evaluate objects that are not evaluated by default like limits,
integrals, sums and products. All objects of this kind will be
evaluated recursively, unless some species were excluded via 'hints'
or unless the 'deep' hint was set to 'False'.
>>> from sympy import Integral
>>> from sympy.abc import x
>>> 2*Integral(x, x)
2*Integral(x, x)
>>> (2*Integral(x, x)).doit()
x**2
>>> (2*Integral(x, x)).doit(deep=False)
2*Integral(x, x)
"""
if hints.get('deep', True):
terms = [term.doit(**hints) if isinstance(term, Basic) else term
for term in self.args]
return self.func(*terms)
else:
return self
def simplify(self, **kwargs):
"""See the simplify function in sympy.simplify"""
from sympy.simplify import simplify
return simplify(self, **kwargs)
def refine(self, assumption=True):
"""See the refine function in sympy.assumptions"""
from sympy.assumptions import refine
return refine(self, assumption)
def _eval_derivative_n_times(self, s, n):
# This is the default evaluator for derivatives (as called by `diff`
# and `Derivative`), it will attempt a loop to derive the expression
# `n` times by calling the corresponding `_eval_derivative` method,
# while leaving the derivative unevaluated if `n` is symbolic. This
# method should be overridden if the object has a closed form for its
# symbolic n-th derivative.
from sympy import Integer
if isinstance(n, (int, Integer)):
obj = self
for i in range(n):
obj2 = obj._eval_derivative(s)
if obj == obj2 or obj2 is None:
break
obj = obj2
return obj2
else:
return None
def rewrite(self, *args, deep=True, **hints):
"""
Rewrite *self* using a defined rule.
Rewriting transforms an expression to another, which is mathematically
equivalent but structurally different. For example you can rewrite
trigonometric functions as complex exponentials or combinatorial
functions as gamma function.
This method takes a *pattern* and a *rule* as positional arguments.
*pattern* is optional parameter which defines the types of expressions
that will be transformed. If it is not passed, all possible expressions
will be rewritten. *rule* defines how the expression will be rewritten.
Parameters
==========
args : *rule*, or *pattern* and *rule*.
- *pattern* is a type or an iterable of types.
- *rule* can be any object.
deep : bool, optional.
If ``True``, subexpressions are recursively transformed. Default is
``True``.
Examples
========
If *pattern* is unspecified, all possible expressions are transformed.
>>> from sympy import cos, sin, exp, I
>>> from sympy.abc import x
>>> expr = cos(x) + I*sin(x)
>>> expr.rewrite(exp)
exp(I*x)
Pattern can be a type or an iterable of types.
>>> expr.rewrite(sin, exp)
exp(I*x)/2 + cos(x) - exp(-I*x)/2
>>> expr.rewrite([cos,], exp)
exp(I*x)/2 + I*sin(x) + exp(-I*x)/2
>>> expr.rewrite([cos, sin], exp)
exp(I*x)
Rewriting behavior can be implemented by defining ``_eval_rewrite()``
method.
>>> from sympy import Expr, sqrt, pi
>>> class MySin(Expr):
... def _eval_rewrite(self, rule, args, **hints):
... x, = args
... if rule == cos:
... return cos(pi/2 - x, evaluate=False)
... if rule == sqrt:
... return sqrt(1 - cos(x)**2)
>>> MySin(MySin(x)).rewrite(cos)
cos(-cos(-x + pi/2) + pi/2)
>>> MySin(x).rewrite(sqrt)
sqrt(1 - cos(x)**2)
Defining ``_eval_rewrite_as_[...]()`` method is supported for backwards
compatibility reason. This may be removed in the future and using it is
discouraged.
>>> class MySin(Expr):
... def _eval_rewrite_as_cos(self, *args, **hints):
... x, = args
... return cos(pi/2 - x, evaluate=False)
>>> MySin(x).rewrite(cos)
cos(-x + pi/2)
"""
if not args:
return self
hints.update(deep=deep)
pattern = args[:-1]
rule = args[-1]
# support old design by _eval_rewrite_as_[...] method
if isinstance(rule, str):
method = "_eval_rewrite_as_%s" % rule
elif hasattr(rule, "__name__"):
# rule is class or function
clsname = rule.__name__
method = "_eval_rewrite_as_%s" % clsname
else:
# rule is instance
clsname = rule.__class__.__name__
method = "_eval_rewrite_as_%s" % clsname
if pattern:
if iterable(pattern[0]):
pattern = pattern[0]
pattern = tuple(p for p in pattern if self.has(p))
if not pattern:
return self
# hereafter, empty pattern is interpreted as all pattern.
return self._rewrite(pattern, rule, method, **hints)
def _rewrite(self, pattern, rule, method, **hints):
deep = hints.pop('deep', True)
if deep:
args = [a._rewrite(pattern, rule, method, **hints)
for a in self.args]
else:
args = self.args
if not pattern or any(isinstance(self, p) for p in pattern):
meth = getattr(self, method, None)
if meth is not None:
rewritten = meth(*args, **hints)
else:
rewritten = self._eval_rewrite(rule, args, **hints)
if rewritten is not None:
return rewritten
if not args:
return self
return self.func(*args)
def _eval_rewrite(self, rule, args, **hints):
return None
_constructor_postprocessor_mapping = {} # type: ignore
@classmethod
def _exec_constructor_postprocessors(cls, obj):
# WARNING: This API is experimental.
# This is an experimental API that introduces constructor
# postprosessors for SymPy Core elements. If an argument of a SymPy
# expression has a `_constructor_postprocessor_mapping` attribute, it will
# be interpreted as a dictionary containing lists of postprocessing
# functions for matching expression node names.
clsname = obj.__class__.__name__
postprocessors = defaultdict(list)
for i in obj.args:
try:
postprocessor_mappings = (
Basic._constructor_postprocessor_mapping[cls].items()
for cls in type(i).mro()
if cls in Basic._constructor_postprocessor_mapping
)
for k, v in chain.from_iterable(postprocessor_mappings):
postprocessors[k].extend([j for j in v if j not in postprocessors[k]])
except TypeError:
pass
for f in postprocessors.get(clsname, []):
obj = f(obj)
return obj
class Atom(Basic):
"""
A parent class for atomic things. An atom is an expression with no subexpressions.
Examples
========
Symbol, Number, Rational, Integer, ...
But not: Add, Mul, Pow, ...
"""
is_Atom = True
__slots__ = ()
def matches(self, expr, repl_dict={}, old=False):
if self == expr:
return repl_dict.copy()
def xreplace(self, rule, hack2=False):
return rule.get(self, self)
def doit(self, **hints):
return self
@classmethod
def class_key(cls):
return 2, 0, cls.__name__
@cacheit
def sort_key(self, order=None):
return self.class_key(), (1, (str(self),)), S.One.sort_key(), S.One
def _eval_simplify(self, **kwargs):
return self
@property
def _sorted_args(self):
# this is here as a safeguard against accidentally using _sorted_args
# on Atoms -- they cannot be rebuilt as atom.func(*atom._sorted_args)
# since there are no args. So the calling routine should be checking
# to see that this property is not called for Atoms.
raise AttributeError('Atoms have no args. It might be necessary'
' to make a check for Atoms in the calling code.')
def _aresame(a, b):
"""Return True if a and b are structurally the same, else False.
Examples
========
In SymPy (as in Python) two numbers compare the same if they
have the same underlying base-2 representation even though
they may not be the same type:
>>> from sympy import S
>>> 2.0 == S(2)
True
>>> 0.5 == S.Half
True
This routine was written to provide a query for such cases that
would give false when the types do not match:
>>> from sympy.core.basic import _aresame
>>> _aresame(S(2.0), S(2))
False
"""
from .numbers import Number
from .function import AppliedUndef, UndefinedFunction as UndefFunc
if isinstance(a, Number) and isinstance(b, Number):
return a == b and a.__class__ == b.__class__
for i, j in zip_longest(preorder_traversal(a), preorder_traversal(b)):
if i != j or type(i) != type(j):
if ((isinstance(i, UndefFunc) and isinstance(j, UndefFunc)) or
(isinstance(i, AppliedUndef) and isinstance(j, AppliedUndef))):
if i.class_key() != j.class_key():
return False
else:
return False
return True
def _ne(a, b):
# use this as a second test after `a != b` if you want to make
# sure that things are truly equal, e.g.
# a, b = 0.5, S.Half
# a !=b or _ne(a, b) -> True
from .numbers import Number
# 0.5 == S.Half
if isinstance(a, Number) and isinstance(b, Number):
return a.__class__ != b.__class__
def _atomic(e, recursive=False):
"""Return atom-like quantities as far as substitution is
concerned: Derivatives, Functions and Symbols. Don't
return any 'atoms' that are inside such quantities unless
they also appear outside, too, unless `recursive` is True.
Examples
========
>>> from sympy import Derivative, Function, cos
>>> from sympy.abc import x, y
>>> from sympy.core.basic import _atomic
>>> f = Function('f')
>>> _atomic(x + y)
{x, y}
>>> _atomic(x + f(y))
{x, f(y)}
>>> _atomic(Derivative(f(x), x) + cos(x) + y)
{y, cos(x), Derivative(f(x), x)}
"""
from sympy import Derivative, Function, Symbol
pot = preorder_traversal(e)
seen = set()
if isinstance(e, Basic):
free = getattr(e, "free_symbols", None)
if free is None:
return {e}
else:
return set()
atoms = set()
for p in pot:
if p in seen:
pot.skip()
continue
seen.add(p)
if isinstance(p, Symbol) and p in free:
atoms.add(p)
elif isinstance(p, (Derivative, Function)):
if not recursive:
pot.skip()
atoms.add(p)
return atoms
class preorder_traversal:
"""
Do a pre-order traversal of a tree.
This iterator recursively yields nodes that it has visited in a pre-order
fashion. That is, it yields the current node then descends through the
tree breadth-first to yield all of a node's children's pre-order
traversal.
For an expression, the order of the traversal depends on the order of
.args, which in many cases can be arbitrary.
Parameters
==========
node : sympy expression
The expression to traverse.
keys : (default None) sort key(s)
The key(s) used to sort args of Basic objects. When None, args of Basic
objects are processed in arbitrary order. If key is defined, it will
be passed along to ordered() as the only key(s) to use to sort the
arguments; if ``key`` is simply True then the default keys of ordered
will be used.
Yields
======
subtree : sympy expression
All of the subtrees in the tree.
Examples
========
>>> from sympy import symbols
>>> from sympy.core.basic import preorder_traversal
>>> x, y, z = symbols('x y z')
The nodes are returned in the order that they are encountered unless key
is given; simply passing key=True will guarantee that the traversal is
unique.
>>> list(preorder_traversal((x + y)*z, keys=None)) # doctest: +SKIP
[z*(x + y), z, x + y, y, x]
>>> list(preorder_traversal((x + y)*z, keys=True))
[z*(x + y), z, x + y, x, y]
"""
def __init__(self, node, keys=None):
self._skip_flag = False
self._pt = self._preorder_traversal(node, keys)
def _preorder_traversal(self, node, keys):
yield node
if self._skip_flag:
self._skip_flag = False
return
if isinstance(node, Basic):
if not keys and hasattr(node, '_argset'):
# LatticeOp keeps args as a set. We should use this if we
# don't care about the order, to prevent unnecessary sorting.
args = node._argset
else:
args = node.args
if keys:
if keys != True:
args = ordered(args, keys, default=False)
else:
args = ordered(args)
for arg in args:
yield from self._preorder_traversal(arg, keys)
elif iterable(node):
for item in node:
yield from self._preorder_traversal(item, keys)
def skip(self):
"""
Skip yielding current node's (last yielded node's) subtrees.
Examples
========
>>> from sympy.core import symbols
>>> from sympy.core.basic import preorder_traversal
>>> x, y, z = symbols('x y z')
>>> pt = preorder_traversal((x+y*z)*z)
>>> for i in pt:
... print(i)
... if i == x+y*z:
... pt.skip()
z*(x + y*z)
z
x + y*z
"""
self._skip_flag = True
def __next__(self):
return next(self._pt)
def __iter__(self):
return self
def _make_find_query(query):
"""Convert the argument of Basic.find() into a callable"""
try:
query = _sympify(query)
except SympifyError:
pass
if isinstance(query, type):
return lambda expr: isinstance(expr, query)
elif isinstance(query, Basic):
return lambda expr: expr.match(query) is not None
return query
# Delayed to avoid cyclic import
from .singleton import S
|
5cd4b7ea3fbe21c63b1010f616aaad1acbbd4573fe9ce6eb4c5df38eb363c427 | from typing import Callable
from math import log as _log
from .sympify import _sympify
from .cache import cacheit
from .singleton import S
from .expr import Expr
from .evalf import PrecisionExhausted
from .function import (_coeff_isneg, expand_complex, expand_multinomial,
expand_mul, _mexpand)
from .logic import fuzzy_bool, fuzzy_not, fuzzy_and, fuzzy_or
from .compatibility import as_int, HAS_GMPY, gmpy
from .parameters import global_parameters
from sympy.utilities.iterables import sift
from sympy.utilities.exceptions import SymPyDeprecationWarning
from sympy.multipledispatch import Dispatcher
from mpmath.libmp import sqrtrem as mpmath_sqrtrem
from math import sqrt as _sqrt
def isqrt(n):
"""Return the largest integer less than or equal to sqrt(n)."""
if n < 0:
raise ValueError("n must be nonnegative")
n = int(n)
# Fast path: with IEEE 754 binary64 floats and a correctly-rounded
# math.sqrt, int(math.sqrt(n)) works for any integer n satisfying 0 <= n <
# 4503599761588224 = 2**52 + 2**27. But Python doesn't guarantee either
# IEEE 754 format floats *or* correct rounding of math.sqrt, so check the
# answer and fall back to the slow method if necessary.
if n < 4503599761588224:
s = int(_sqrt(n))
if 0 <= n - s*s <= 2*s:
return s
return integer_nthroot(n, 2)[0]
def integer_nthroot(y, n):
"""
Return a tuple containing x = floor(y**(1/n))
and a boolean indicating whether the result is exact (that is,
whether x**n == y).
Examples
========
>>> from sympy import integer_nthroot
>>> integer_nthroot(16, 2)
(4, True)
>>> integer_nthroot(26, 2)
(5, False)
To simply determine if a number is a perfect square, the is_square
function should be used:
>>> from sympy.ntheory.primetest import is_square
>>> is_square(26)
False
See Also
========
sympy.ntheory.primetest.is_square
integer_log
"""
y, n = as_int(y), as_int(n)
if y < 0:
raise ValueError("y must be nonnegative")
if n < 1:
raise ValueError("n must be positive")
if HAS_GMPY and n < 2**63:
# Currently it works only for n < 2**63, else it produces TypeError
# sympy issue: https://github.com/sympy/sympy/issues/18374
# gmpy2 issue: https://github.com/aleaxit/gmpy/issues/257
if HAS_GMPY >= 2:
x, t = gmpy.iroot(y, n)
else:
x, t = gmpy.root(y, n)
return as_int(x), bool(t)
return _integer_nthroot_python(y, n)
def _integer_nthroot_python(y, n):
if y in (0, 1):
return y, True
if n == 1:
return y, True
if n == 2:
x, rem = mpmath_sqrtrem(y)
return int(x), not rem
if n > y:
return 1, False
# Get initial estimate for Newton's method. Care must be taken to
# avoid overflow
try:
guess = int(y**(1./n) + 0.5)
except OverflowError:
exp = _log(y, 2)/n
if exp > 53:
shift = int(exp - 53)
guess = int(2.0**(exp - shift) + 1) << shift
else:
guess = int(2.0**exp)
if guess > 2**50:
# Newton iteration
xprev, x = -1, guess
while 1:
t = x**(n - 1)
xprev, x = x, ((n - 1)*x + y//t)//n
if abs(x - xprev) < 2:
break
else:
x = guess
# Compensate
t = x**n
while t < y:
x += 1
t = x**n
while t > y:
x -= 1
t = x**n
return int(x), t == y # int converts long to int if possible
def integer_log(y, x):
r"""
Returns ``(e, bool)`` where e is the largest nonnegative integer
such that :math:`|y| \geq |x^e|` and ``bool`` is True if $y = x^e$.
Examples
========
>>> from sympy import integer_log
>>> integer_log(125, 5)
(3, True)
>>> integer_log(17, 9)
(1, False)
>>> integer_log(4, -2)
(2, True)
>>> integer_log(-125,-5)
(3, True)
See Also
========
integer_nthroot
sympy.ntheory.primetest.is_square
sympy.ntheory.factor_.multiplicity
sympy.ntheory.factor_.perfect_power
"""
if x == 1:
raise ValueError('x cannot take value as 1')
if y == 0:
raise ValueError('y cannot take value as 0')
if x in (-2, 2):
x = int(x)
y = as_int(y)
e = y.bit_length() - 1
return e, x**e == y
if x < 0:
n, b = integer_log(y if y > 0 else -y, -x)
return n, b and bool(n % 2 if y < 0 else not n % 2)
x = as_int(x)
y = as_int(y)
r = e = 0
while y >= x:
d = x
m = 1
while y >= d:
y, rem = divmod(y, d)
r = r or rem
e += m
if y > d:
d *= d
m *= 2
return e, r == 0 and y == 1
class Pow(Expr):
"""
Defines the expression x**y as "x raised to a power y"
Singleton definitions involving (0, 1, -1, oo, -oo, I, -I):
+--------------+---------+-----------------------------------------------+
| expr | value | reason |
+==============+=========+===============================================+
| z**0 | 1 | Although arguments over 0**0 exist, see [2]. |
+--------------+---------+-----------------------------------------------+
| z**1 | z | |
+--------------+---------+-----------------------------------------------+
| (-oo)**(-1) | 0 | |
+--------------+---------+-----------------------------------------------+
| (-1)**-1 | -1 | |
+--------------+---------+-----------------------------------------------+
| S.Zero**-1 | zoo | This is not strictly true, as 0**-1 may be |
| | | undefined, but is convenient in some contexts |
| | | where the base is assumed to be positive. |
+--------------+---------+-----------------------------------------------+
| 1**-1 | 1 | |
+--------------+---------+-----------------------------------------------+
| oo**-1 | 0 | |
+--------------+---------+-----------------------------------------------+
| 0**oo | 0 | Because for all complex numbers z near |
| | | 0, z**oo -> 0. |
+--------------+---------+-----------------------------------------------+
| 0**-oo | zoo | This is not strictly true, as 0**oo may be |
| | | oscillating between positive and negative |
| | | values or rotating in the complex plane. |
| | | It is convenient, however, when the base |
| | | is positive. |
+--------------+---------+-----------------------------------------------+
| 1**oo | nan | Because there are various cases where |
| 1**-oo | | lim(x(t),t)=1, lim(y(t),t)=oo (or -oo), |
| | | but lim( x(t)**y(t), t) != 1. See [3]. |
+--------------+---------+-----------------------------------------------+
| b**zoo | nan | Because b**z has no limit as z -> zoo |
+--------------+---------+-----------------------------------------------+
| (-1)**oo | nan | Because of oscillations in the limit. |
| (-1)**(-oo) | | |
+--------------+---------+-----------------------------------------------+
| oo**oo | oo | |
+--------------+---------+-----------------------------------------------+
| oo**-oo | 0 | |
+--------------+---------+-----------------------------------------------+
| (-oo)**oo | nan | |
| (-oo)**-oo | | |
+--------------+---------+-----------------------------------------------+
| oo**I | nan | oo**e could probably be best thought of as |
| (-oo)**I | | the limit of x**e for real x as x tends to |
| | | oo. If e is I, then the limit does not exist |
| | | and nan is used to indicate that. |
+--------------+---------+-----------------------------------------------+
| oo**(1+I) | zoo | If the real part of e is positive, then the |
| (-oo)**(1+I) | | limit of abs(x**e) is oo. So the limit value |
| | | is zoo. |
+--------------+---------+-----------------------------------------------+
| oo**(-1+I) | 0 | If the real part of e is negative, then the |
| -oo**(-1+I) | | limit is 0. |
+--------------+---------+-----------------------------------------------+
Because symbolic computations are more flexible that floating point
calculations and we prefer to never return an incorrect answer,
we choose not to conform to all IEEE 754 conventions. This helps
us avoid extra test-case code in the calculation of limits.
See Also
========
sympy.core.numbers.Infinity
sympy.core.numbers.NegativeInfinity
sympy.core.numbers.NaN
References
==========
.. [1] https://en.wikipedia.org/wiki/Exponentiation
.. [2] https://en.wikipedia.org/wiki/Exponentiation#Zero_to_the_power_of_zero
.. [3] https://en.wikipedia.org/wiki/Indeterminate_forms
"""
is_Pow = True
__slots__ = ('is_commutative',)
@cacheit
def __new__(cls, b, e, evaluate=None):
if evaluate is None:
evaluate = global_parameters.evaluate
from sympy.functions.elementary.exponential import exp_polar
b = _sympify(b)
e = _sympify(e)
# XXX: This can be removed when non-Expr args are disallowed rather
# than deprecated.
from sympy.core.relational import Relational
if isinstance(b, Relational) or isinstance(e, Relational):
raise TypeError('Relational can not be used in Pow')
# XXX: This should raise TypeError once deprecation period is over:
if not (isinstance(b, Expr) and isinstance(e, Expr)):
SymPyDeprecationWarning(
feature="Pow with non-Expr args",
useinstead="Expr args",
issue=19445,
deprecated_since_version="1.7"
).warn()
if evaluate:
if b is S.Zero and e is S.NegativeInfinity:
return S.ComplexInfinity
if e is S.ComplexInfinity:
return S.NaN
if e is S.Zero:
return S.One
elif e is S.One:
return b
elif e == -1 and not b:
return S.ComplexInfinity
elif e.__class__.__name__ == "AccumulationBounds":
if b == S.Exp1:
from sympy import AccumBounds
return AccumBounds(Pow(b, e.min), Pow(b, e.max))
# Only perform autosimplification if exponent or base is a Symbol or number
elif (b.is_Symbol or b.is_number) and (e.is_Symbol or e.is_number) and\
e.is_integer and _coeff_isneg(b):
if e.is_even:
b = -b
elif e.is_odd:
return -Pow(-b, e)
if S.NaN in (b, e): # XXX S.NaN**x -> S.NaN under assumption that x != 0
return S.NaN
elif b is S.One:
if abs(e).is_infinite:
return S.NaN
return S.One
else:
# recognize base as E
if not e.is_Atom and b is not S.Exp1 and not isinstance(b, exp_polar):
from sympy import numer, denom, log, sign, im, factor_terms
c, ex = factor_terms(e, sign=False).as_coeff_Mul()
den = denom(ex)
if isinstance(den, log) and den.args[0] == b:
return S.Exp1**(c*numer(ex))
elif den.is_Add:
s = sign(im(b))
if s.is_Number and s and den == \
log(-factor_terms(b, sign=False)) + s*S.ImaginaryUnit*S.Pi:
return S.Exp1**(c*numer(ex))
obj = b._eval_power(e)
if obj is not None:
return obj
obj = Expr.__new__(cls, b, e)
obj = cls._exec_constructor_postprocessors(obj)
if not isinstance(obj, Pow):
return obj
obj.is_commutative = (b.is_commutative and e.is_commutative)
return obj
def inverse(self, argindex=1):
if self.base == S.Exp1:
from sympy import log
return log
return None
@property
def base(self):
return self._args[0]
@property
def exp(self):
return self._args[1]
@classmethod
def class_key(cls):
return 3, 2, cls.__name__
def _eval_refine(self, assumptions):
from sympy.assumptions.ask import ask, Q
b, e = self.as_base_exp()
if ask(Q.integer(e), assumptions) and _coeff_isneg(b):
if ask(Q.even(e), assumptions):
return Pow(-b, e)
elif ask(Q.odd(e), assumptions):
return -Pow(-b, e)
def _eval_power(self, other):
from sympy import arg, exp, floor, im, log, re, sign
b, e = self.as_base_exp()
if b is S.NaN:
return (b**e)**other # let __new__ handle it
s = None
if other.is_integer:
s = 1
elif b.is_polar: # e.g. exp_polar, besselj, var('p', polar=True)...
s = 1
elif e.is_extended_real is not None:
# helper functions ===========================
def _half(e):
"""Return True if the exponent has a literal 2 as the
denominator, else None."""
if getattr(e, 'q', None) == 2:
return True
n, d = e.as_numer_denom()
if n.is_integer and d == 2:
return True
def _n2(e):
"""Return ``e`` evaluated to a Number with 2 significant
digits, else None."""
try:
rv = e.evalf(2, strict=True)
if rv.is_Number:
return rv
except PrecisionExhausted:
pass
# ===================================================
if e.is_extended_real:
# we need _half(other) with constant floor or
# floor(S.Half - e*arg(b)/2/pi) == 0
# handle -1 as special case
if e == -1:
# floor arg. is 1/2 + arg(b)/2/pi
if _half(other):
if b.is_negative is True:
return S.NegativeOne**other*Pow(-b, e*other)
elif b.is_negative is False:
return Pow(b, -other)
elif e.is_even:
if b.is_extended_real:
b = abs(b)
if b.is_imaginary:
b = abs(im(b))*S.ImaginaryUnit
if (abs(e) < 1) == True or e == 1:
s = 1 # floor = 0
elif b.is_extended_nonnegative:
s = 1 # floor = 0
elif re(b).is_extended_nonnegative and (abs(e) < 2) == True:
s = 1 # floor = 0
elif fuzzy_not(im(b).is_zero) and abs(e) == 2:
s = 1 # floor = 0
elif _half(other):
s = exp(2*S.Pi*S.ImaginaryUnit*other*floor(
S.Half - e*arg(b)/(2*S.Pi)))
if s.is_extended_real and _n2(sign(s) - s) == 0:
s = sign(s)
else:
s = None
else:
# e.is_extended_real is False requires:
# _half(other) with constant floor or
# floor(S.Half - im(e*log(b))/2/pi) == 0
try:
s = exp(2*S.ImaginaryUnit*S.Pi*other*
floor(S.Half - im(e*log(b))/2/S.Pi))
# be careful to test that s is -1 or 1 b/c sign(I) == I:
# so check that s is real
if s.is_extended_real and _n2(sign(s) - s) == 0:
s = sign(s)
else:
s = None
except PrecisionExhausted:
s = None
if s is not None:
return s*Pow(b, e*other)
def _eval_Mod(self, q):
r"""A dispatched function to compute `b^e \bmod q`, dispatched
by ``Mod``.
Notes
=====
Algorithms:
1. For unevaluated integer power, use built-in ``pow`` function
with 3 arguments, if powers are not too large wrt base.
2. For very large powers, use totient reduction if e >= lg(m).
Bound on m, is for safe factorization memory wise ie m^(1/4).
For pollard-rho to be faster than built-in pow lg(e) > m^(1/4)
check is added.
3. For any unevaluated power found in `b` or `e`, the step 2
will be recursed down to the base and the exponent
such that the `b \bmod q` becomes the new base and
``\phi(q) + e \bmod \phi(q)`` becomes the new exponent, and then
the computation for the reduced expression can be done.
"""
from sympy.ntheory import totient
from .mod import Mod
base, exp = self.base, self.exp
if exp.is_integer and exp.is_positive:
if q.is_integer and base % q == 0:
return S.Zero
if base.is_Integer and exp.is_Integer and q.is_Integer:
b, e, m = int(base), int(exp), int(q)
mb = m.bit_length()
if mb <= 80 and e >= mb and e.bit_length()**4 >= m:
phi = totient(m)
return Integer(pow(b, phi + e%phi, m))
return Integer(pow(b, e, m))
if isinstance(base, Pow) and base.is_integer and base.is_number:
base = Mod(base, q)
return Mod(Pow(base, exp, evaluate=False), q)
if isinstance(exp, Pow) and exp.is_integer and exp.is_number:
bit_length = int(q).bit_length()
# XXX Mod-Pow actually attempts to do a hanging evaluation
# if this dispatched function returns None.
# May need some fixes in the dispatcher itself.
if bit_length <= 80:
phi = totient(q)
exp = phi + Mod(exp, phi)
return Mod(Pow(base, exp, evaluate=False), q)
def _eval_is_even(self):
if self.exp.is_integer and self.exp.is_positive:
return self.base.is_even
def _eval_is_negative(self):
ext_neg = Pow._eval_is_extended_negative(self)
if ext_neg is True:
return self.is_finite
return ext_neg
def _eval_is_positive(self):
ext_pos = Pow._eval_is_extended_positive(self)
if ext_pos is True:
return self.is_finite
return ext_pos
def _eval_is_extended_positive(self):
from sympy import log
if self.base == self.exp:
if self.base.is_extended_nonnegative:
return True
elif self.base.is_positive:
if self.exp.is_real:
return True
elif self.base.is_extended_negative:
if self.exp.is_even:
return True
if self.exp.is_odd:
return False
elif self.base.is_zero:
if self.exp.is_extended_real:
return self.exp.is_zero
elif self.base.is_extended_nonpositive:
if self.exp.is_odd:
return False
elif self.base.is_imaginary:
if self.exp.is_integer:
m = self.exp % 4
if m.is_zero:
return True
if m.is_integer and m.is_zero is False:
return False
if self.exp.is_imaginary:
return log(self.base).is_imaginary
def _eval_is_extended_negative(self):
if self.exp is S(1)/2:
if self.base.is_complex or self.base.is_extended_real:
return False
if self.base.is_extended_negative:
if self.exp.is_odd and self.base.is_finite:
return True
if self.exp.is_even:
return False
elif self.base.is_extended_positive:
if self.exp.is_extended_real:
return False
elif self.base.is_zero:
if self.exp.is_extended_real:
return False
elif self.base.is_extended_nonnegative:
if self.exp.is_extended_nonnegative:
return False
elif self.base.is_extended_nonpositive:
if self.exp.is_even:
return False
elif self.base.is_extended_real:
if self.exp.is_even:
return False
def _eval_is_zero(self):
if self.base.is_zero:
if self.exp.is_extended_positive:
return True
elif self.exp.is_extended_nonpositive:
return False
elif self.base == S.Exp1:
return self.exp is S.NegativeInfinity
elif self.base.is_zero is False:
if self.base.is_finite and self.exp.is_finite:
return False
elif self.exp.is_negative:
return self.base.is_infinite
elif self.exp.is_nonnegative:
return False
elif self.exp.is_infinite and self.exp.is_extended_real:
if (1 - abs(self.base)).is_extended_positive:
return self.exp.is_extended_positive
elif (1 - abs(self.base)).is_extended_negative:
return self.exp.is_extended_negative
elif self.base.is_finite and self.exp.is_negative:
# when self.base.is_zero is None
return False
def _eval_is_integer(self):
b, e = self.args
if b.is_rational:
if b.is_integer is False and e.is_positive:
return False # rat**nonneg
if b.is_integer and e.is_integer:
if b is S.NegativeOne:
return True
if e.is_nonnegative or e.is_positive:
return True
if b.is_integer and e.is_negative and (e.is_finite or e.is_integer):
if fuzzy_not((b - 1).is_zero) and fuzzy_not((b + 1).is_zero):
return False
if b.is_Number and e.is_Number:
check = self.func(*self.args)
return check.is_Integer
if e.is_negative and b.is_positive and (b - 1).is_positive:
return False
if e.is_negative and b.is_negative and (b + 1).is_negative:
return False
def _eval_is_extended_real(self):
from ..functions import arg, log, exp
from .mul import Mul
if self.base is S.Exp1:
if self.exp.is_extended_real:
return True
elif self.exp.is_imaginary:
return (2*S.ImaginaryUnit*self.exp/S.Pi).is_even
real_b = self.base.is_extended_real
if real_b is None:
if self.base.func == exp and self.base.exp.is_imaginary:
return self.exp.is_imaginary
if self.base.func == Pow and self.base.base is S.Exp1 and self.base.exp.is_imaginary:
return self.exp.is_imaginary
return
real_e = self.exp.is_extended_real
if real_e is None:
return
if real_b and real_e:
if self.base.is_extended_positive:
return True
elif self.base.is_extended_nonnegative and self.exp.is_extended_nonnegative:
return True
elif self.exp.is_integer and self.base.is_extended_nonzero:
return True
elif self.exp.is_integer and self.exp.is_nonnegative:
return True
elif self.base.is_extended_negative:
if self.exp.is_Rational:
return False
if real_e and self.exp.is_extended_negative and self.base.is_zero is False:
return Pow(self.base, -self.exp).is_extended_real
im_b = self.base.is_imaginary
im_e = self.exp.is_imaginary
if im_b:
if self.exp.is_integer:
if self.exp.is_even:
return True
elif self.exp.is_odd:
return False
elif im_e and log(self.base).is_imaginary:
return True
elif self.exp.is_Add:
c, a = self.exp.as_coeff_Add()
if c and c.is_Integer:
return Mul(
self.base**c, self.base**a, evaluate=False).is_extended_real
elif self.base in (-S.ImaginaryUnit, S.ImaginaryUnit):
if (self.exp/2).is_integer is False:
return False
if real_b and im_e:
if self.base is S.NegativeOne:
return True
c = self.exp.coeff(S.ImaginaryUnit)
if c:
if self.base.is_rational and c.is_rational:
if self.base.is_nonzero and (self.base - 1).is_nonzero and c.is_nonzero:
return False
ok = (c*log(self.base)/S.Pi).is_integer
if ok is not None:
return ok
if real_b is False: # we already know it's not imag
i = arg(self.base)*self.exp/S.Pi
if i.is_complex: # finite
return i.is_integer
def _eval_is_complex(self):
if self.base == S.Exp1:
return fuzzy_or([self.exp.is_complex, self.exp.is_extended_negative])
if all(a.is_complex for a in self.args) and self._eval_is_finite():
return True
def _eval_is_imaginary(self):
from sympy import arg, log
if self.base.is_imaginary:
if self.exp.is_integer:
odd = self.exp.is_odd
if odd is not None:
return odd
return
if self.base == S.Exp1:
f = 2 * self.exp / (S.Pi*S.ImaginaryUnit)
# exp(pi*integer) = 1 or -1, so not imaginary
if f.is_even:
return False
# exp(pi*integer + pi/2) = I or -I, so it is imaginary
if f.is_odd:
return True
return None
if self.exp.is_imaginary:
imlog = log(self.base).is_imaginary
if imlog is not None:
return False # I**i -> real; (2*I)**i -> complex ==> not imaginary
if self.base.is_extended_real and self.exp.is_extended_real:
if self.base.is_positive:
return False
else:
rat = self.exp.is_rational
if not rat:
return rat
if self.exp.is_integer:
return False
else:
half = (2*self.exp).is_integer
if half:
return self.base.is_negative
return half
if self.base.is_extended_real is False: # we already know it's not imag
i = arg(self.base)*self.exp/S.Pi
isodd = (2*i).is_odd
if isodd is not None:
return isodd
def _eval_is_odd(self):
if self.exp.is_integer:
if self.exp.is_positive:
return self.base.is_odd
elif self.exp.is_nonnegative and self.base.is_odd:
return True
elif self.base is S.NegativeOne:
return True
def _eval_is_finite(self):
if self.exp.is_negative:
if self.base.is_zero:
return False
if self.base.is_infinite or self.base.is_nonzero:
return True
c1 = self.base.is_finite
if c1 is None:
return
c2 = self.exp.is_finite
if c2 is None:
return
if c1 and c2:
if self.exp.is_nonnegative or fuzzy_not(self.base.is_zero):
return True
def _eval_is_prime(self):
'''
An integer raised to the n(>=2)-th power cannot be a prime.
'''
if self.base.is_integer and self.exp.is_integer and (self.exp - 1).is_positive:
return False
def _eval_is_composite(self):
"""
A power is composite if both base and exponent are greater than 1
"""
if (self.base.is_integer and self.exp.is_integer and
((self.base - 1).is_positive and (self.exp - 1).is_positive or
(self.base + 1).is_negative and self.exp.is_positive and self.exp.is_even)):
return True
def _eval_is_polar(self):
return self.base.is_polar
def _eval_subs(self, old, new):
from sympy import exp, log, Symbol, AccumBounds
if isinstance(self.exp, AccumBounds):
b = self.base.subs(old, new)
e = self.exp.subs(old, new)
if isinstance(e, AccumBounds):
return e.__rpow__(b)
return self.func(b, e)
def _check(ct1, ct2, old):
"""Return (bool, pow, remainder_pow) where, if bool is True, then the
exponent of Pow `old` will combine with `pow` so the substitution
is valid, otherwise bool will be False.
For noncommutative objects, `pow` will be an integer, and a factor
`Pow(old.base, remainder_pow)` needs to be included. If there is
no such factor, None is returned. For commutative objects,
remainder_pow is always None.
cti are the coefficient and terms of an exponent of self or old
In this _eval_subs routine a change like (b**(2*x)).subs(b**x, y)
will give y**2 since (b**x)**2 == b**(2*x); if that equality does
not hold then the substitution should not occur so `bool` will be
False.
"""
coeff1, terms1 = ct1
coeff2, terms2 = ct2
if terms1 == terms2:
if old.is_commutative:
# Allow fractional powers for commutative objects
pow = coeff1/coeff2
try:
as_int(pow, strict=False)
combines = True
except ValueError:
combines = isinstance(Pow._eval_power(
Pow(*old.as_base_exp(), evaluate=False),
pow), (Pow, exp, Symbol))
return combines, pow, None
else:
# With noncommutative symbols, substitute only integer powers
if not isinstance(terms1, tuple):
terms1 = (terms1,)
if not all(term.is_integer for term in terms1):
return False, None, None
try:
# Round pow toward zero
pow, remainder = divmod(as_int(coeff1), as_int(coeff2))
if pow < 0 and remainder != 0:
pow += 1
remainder -= as_int(coeff2)
if remainder == 0:
remainder_pow = None
else:
remainder_pow = Mul(remainder, *terms1)
return True, pow, remainder_pow
except ValueError:
# Can't substitute
pass
return False, None, None
if old == self.base or (old == exp and self.base == S.Exp1):
if new.is_Function and isinstance(new, Callable):
return new(self.exp._subs(old, new))
else:
return new**self.exp._subs(old, new)
# issue 10829: (4**x - 3*y + 2).subs(2**x, y) -> y**2 - 3*y + 2
if isinstance(old, self.func) and self.exp == old.exp:
l = log(self.base, old.base)
if l.is_Number:
return Pow(new, l)
if isinstance(old, self.func) and self.base == old.base:
if self.exp.is_Add is False:
ct1 = self.exp.as_independent(Symbol, as_Add=False)
ct2 = old.exp.as_independent(Symbol, as_Add=False)
ok, pow, remainder_pow = _check(ct1, ct2, old)
if ok:
# issue 5180: (x**(6*y)).subs(x**(3*y),z)->z**2
result = self.func(new, pow)
if remainder_pow is not None:
result = Mul(result, Pow(old.base, remainder_pow))
return result
else: # b**(6*x + a).subs(b**(3*x), y) -> y**2 * b**a
# exp(exp(x) + exp(x**2)).subs(exp(exp(x)), w) -> w * exp(exp(x**2))
oarg = old.exp
new_l = []
o_al = []
ct2 = oarg.as_coeff_mul()
for a in self.exp.args:
newa = a._subs(old, new)
ct1 = newa.as_coeff_mul()
ok, pow, remainder_pow = _check(ct1, ct2, old)
if ok:
new_l.append(new**pow)
if remainder_pow is not None:
o_al.append(remainder_pow)
continue
elif not old.is_commutative and not newa.is_integer:
# If any term in the exponent is non-integer,
# we do not do any substitutions in the noncommutative case
return
o_al.append(newa)
if new_l:
expo = Add(*o_al)
new_l.append(Pow(self.base, expo, evaluate=False) if expo != 1 else self.base)
return Mul(*new_l)
if (isinstance(old, exp) or (old.is_Pow and old.base is S.Exp1)) and self.exp.is_extended_real and self.base.is_positive:
ct1 = old.exp.as_independent(Symbol, as_Add=False)
ct2 = (self.exp*log(self.base)).as_independent(
Symbol, as_Add=False)
ok, pow, remainder_pow = _check(ct1, ct2, old)
if ok:
result = self.func(new, pow) # (2**x).subs(exp(x*log(2)), z) -> z
if remainder_pow is not None:
result = Mul(result, Pow(old.base, remainder_pow))
return result
def as_base_exp(self):
"""Return base and exp of self.
Explnation
==========
If base is 1/Integer, then return Integer, -exp. If this extra
processing is not needed, the base and exp properties will
give the raw arguments
Examples
========
>>> from sympy import Pow, S
>>> p = Pow(S.Half, 2, evaluate=False)
>>> p.as_base_exp()
(2, -2)
>>> p.args
(1/2, 2)
"""
b, e = self.args
if b.is_Rational and b.p == 1 and b.q != 1:
return Integer(b.q), -e
return b, e
def _eval_adjoint(self):
from sympy.functions.elementary.complexes import adjoint
i, p = self.exp.is_integer, self.base.is_positive
if i:
return adjoint(self.base)**self.exp
if p:
return self.base**adjoint(self.exp)
if i is False and p is False:
expanded = expand_complex(self)
if expanded != self:
return adjoint(expanded)
def _eval_conjugate(self):
from sympy.functions.elementary.complexes import conjugate as c
i, p = self.exp.is_integer, self.base.is_positive
if i:
return c(self.base)**self.exp
if p:
return self.base**c(self.exp)
if i is False and p is False:
expanded = expand_complex(self)
if expanded != self:
return c(expanded)
if self.is_extended_real:
return self
def _eval_transpose(self):
from sympy.functions.elementary.complexes import transpose
if self.base == S.Exp1:
return self.func(S.Exp1, self.exp.transpose())
i, p = self.exp.is_integer, (self.base.is_complex or self.base.is_infinite)
if p:
return self.base**self.exp
if i:
return transpose(self.base)**self.exp
if i is False and p is False:
expanded = expand_complex(self)
if expanded != self:
return transpose(expanded)
def _eval_expand_power_exp(self, **hints):
"""a**(n + m) -> a**n*a**m"""
b = self.base
e = self.exp
if b == S.Exp1:
from sympy import Sum, Product
if isinstance(e, Sum) and e.is_commutative:
return Product(self.func(b, e.function), *e.limits)
if e.is_Add and e.is_commutative:
expr = []
for x in e.args:
expr.append(self.func(b, x))
return Mul(*expr)
return self.func(b, e)
def _eval_expand_power_base(self, **hints):
"""(a*b)**n -> a**n * b**n"""
force = hints.get('force', False)
b = self.base
e = self.exp
if not b.is_Mul:
return self
cargs, nc = b.args_cnc(split_1=False)
# expand each term - this is top-level-only
# expansion but we have to watch out for things
# that don't have an _eval_expand method
if nc:
nc = [i._eval_expand_power_base(**hints)
if hasattr(i, '_eval_expand_power_base') else i
for i in nc]
if e.is_Integer:
if e.is_positive:
rv = Mul(*nc*e)
else:
rv = Mul(*[i**-1 for i in nc[::-1]]*-e)
if cargs:
rv *= Mul(*cargs)**e
return rv
if not cargs:
return self.func(Mul(*nc), e, evaluate=False)
nc = [Mul(*nc)]
# sift the commutative bases
other, maybe_real = sift(cargs, lambda x: x.is_extended_real is False,
binary=True)
def pred(x):
if x is S.ImaginaryUnit:
return S.ImaginaryUnit
polar = x.is_polar
if polar:
return True
if polar is None:
return fuzzy_bool(x.is_extended_nonnegative)
sifted = sift(maybe_real, pred)
nonneg = sifted[True]
other += sifted[None]
neg = sifted[False]
imag = sifted[S.ImaginaryUnit]
if imag:
I = S.ImaginaryUnit
i = len(imag) % 4
if i == 0:
pass
elif i == 1:
other.append(I)
elif i == 2:
if neg:
nonn = -neg.pop()
if nonn is not S.One:
nonneg.append(nonn)
else:
neg.append(S.NegativeOne)
else:
if neg:
nonn = -neg.pop()
if nonn is not S.One:
nonneg.append(nonn)
else:
neg.append(S.NegativeOne)
other.append(I)
del imag
# bring out the bases that can be separated from the base
if force or e.is_integer:
# treat all commutatives the same and put nc in other
cargs = nonneg + neg + other
other = nc
else:
# this is just like what is happening automatically, except
# that now we are doing it for an arbitrary exponent for which
# no automatic expansion is done
assert not e.is_Integer
# handle negatives by making them all positive and putting
# the residual -1 in other
if len(neg) > 1:
o = S.One
if not other and neg[0].is_Number:
o *= neg.pop(0)
if len(neg) % 2:
o = -o
for n in neg:
nonneg.append(-n)
if o is not S.One:
other.append(o)
elif neg and other:
if neg[0].is_Number and neg[0] is not S.NegativeOne:
other.append(S.NegativeOne)
nonneg.append(-neg[0])
else:
other.extend(neg)
else:
other.extend(neg)
del neg
cargs = nonneg
other += nc
rv = S.One
if cargs:
if e.is_Rational:
npow, cargs = sift(cargs, lambda x: x.is_Pow and
x.exp.is_Rational and x.base.is_number,
binary=True)
rv = Mul(*[self.func(b.func(*b.args), e) for b in npow])
rv *= Mul(*[self.func(b, e, evaluate=False) for b in cargs])
if other:
rv *= self.func(Mul(*other), e, evaluate=False)
return rv
def _eval_expand_multinomial(self, **hints):
"""(a + b + ..)**n -> a**n + n*a**(n-1)*b + .., n is nonzero integer"""
base, exp = self.args
result = self
if exp.is_Rational and exp.p > 0 and base.is_Add:
if not exp.is_Integer:
n = Integer(exp.p // exp.q)
if not n:
return result
else:
radical, result = self.func(base, exp - n), []
expanded_base_n = self.func(base, n)
if expanded_base_n.is_Pow:
expanded_base_n = \
expanded_base_n._eval_expand_multinomial()
for term in Add.make_args(expanded_base_n):
result.append(term*radical)
return Add(*result)
n = int(exp)
if base.is_commutative:
order_terms, other_terms = [], []
for b in base.args:
if b.is_Order:
order_terms.append(b)
else:
other_terms.append(b)
if order_terms:
# (f(x) + O(x^n))^m -> f(x)^m + m*f(x)^{m-1} *O(x^n)
f = Add(*other_terms)
o = Add(*order_terms)
if n == 2:
return expand_multinomial(f**n, deep=False) + n*f*o
else:
g = expand_multinomial(f**(n - 1), deep=False)
return expand_mul(f*g, deep=False) + n*g*o
if base.is_number:
# Efficiently expand expressions of the form (a + b*I)**n
# where 'a' and 'b' are real numbers and 'n' is integer.
a, b = base.as_real_imag()
if a.is_Rational and b.is_Rational:
if not a.is_Integer:
if not b.is_Integer:
k = self.func(a.q * b.q, n)
a, b = a.p*b.q, a.q*b.p
else:
k = self.func(a.q, n)
a, b = a.p, a.q*b
elif not b.is_Integer:
k = self.func(b.q, n)
a, b = a*b.q, b.p
else:
k = 1
a, b, c, d = int(a), int(b), 1, 0
while n:
if n & 1:
c, d = a*c - b*d, b*c + a*d
n -= 1
a, b = a*a - b*b, 2*a*b
n //= 2
I = S.ImaginaryUnit
if k == 1:
return c + I*d
else:
return Integer(c)/k + I*d/k
p = other_terms
# (x + y)**3 -> x**3 + 3*x**2*y + 3*x*y**2 + y**3
# in this particular example:
# p = [x,y]; n = 3
# so now it's easy to get the correct result -- we get the
# coefficients first:
from sympy import multinomial_coefficients
from sympy.polys.polyutils import basic_from_dict
expansion_dict = multinomial_coefficients(len(p), n)
# in our example: {(3, 0): 1, (1, 2): 3, (0, 3): 1, (2, 1): 3}
# and now construct the expression.
return basic_from_dict(expansion_dict, *p)
else:
if n == 2:
return Add(*[f*g for f in base.args for g in base.args])
else:
multi = (base**(n - 1))._eval_expand_multinomial()
if multi.is_Add:
return Add(*[f*g for f in base.args
for g in multi.args])
else:
# XXX can this ever happen if base was an Add?
return Add(*[f*multi for f in base.args])
elif (exp.is_Rational and exp.p < 0 and base.is_Add and
abs(exp.p) > exp.q):
return 1 / self.func(base, -exp)._eval_expand_multinomial()
elif exp.is_Add and base.is_Number:
# a + b a b
# n --> n n , where n, a, b are Numbers
coeff, tail = S.One, S.Zero
for term in exp.args:
if term.is_Number:
coeff *= self.func(base, term)
else:
tail += term
return coeff * self.func(base, tail)
else:
return result
def as_real_imag(self, deep=True, **hints):
from sympy import atan2, cos, im, re, sin
from sympy.polys.polytools import poly
if self.exp.is_Integer:
exp = self.exp
re_e, im_e = self.base.as_real_imag(deep=deep)
if not im_e:
return self, S.Zero
a, b = symbols('a b', cls=Dummy)
if exp >= 0:
if re_e.is_Number and im_e.is_Number:
# We can be more efficient in this case
expr = expand_multinomial(self.base**exp)
if expr != self:
return expr.as_real_imag()
expr = poly(
(a + b)**exp) # a = re, b = im; expr = (a + b*I)**exp
else:
mag = re_e**2 + im_e**2
re_e, im_e = re_e/mag, -im_e/mag
if re_e.is_Number and im_e.is_Number:
# We can be more efficient in this case
expr = expand_multinomial((re_e + im_e*S.ImaginaryUnit)**-exp)
if expr != self:
return expr.as_real_imag()
expr = poly((a + b)**-exp)
# Terms with even b powers will be real
r = [i for i in expr.terms() if not i[0][1] % 2]
re_part = Add(*[cc*a**aa*b**bb for (aa, bb), cc in r])
# Terms with odd b powers will be imaginary
r = [i for i in expr.terms() if i[0][1] % 4 == 1]
im_part1 = Add(*[cc*a**aa*b**bb for (aa, bb), cc in r])
r = [i for i in expr.terms() if i[0][1] % 4 == 3]
im_part3 = Add(*[cc*a**aa*b**bb for (aa, bb), cc in r])
return (re_part.subs({a: re_e, b: S.ImaginaryUnit*im_e}),
im_part1.subs({a: re_e, b: im_e}) + im_part3.subs({a: re_e, b: -im_e}))
elif self.exp.is_Rational:
re_e, im_e = self.base.as_real_imag(deep=deep)
if im_e.is_zero and self.exp is S.Half:
if re_e.is_extended_nonnegative:
return self, S.Zero
if re_e.is_extended_nonpositive:
return S.Zero, (-self.base)**self.exp
# XXX: This is not totally correct since for x**(p/q) with
# x being imaginary there are actually q roots, but
# only a single one is returned from here.
r = self.func(self.func(re_e, 2) + self.func(im_e, 2), S.Half)
t = atan2(im_e, re_e)
rp, tp = self.func(r, self.exp), t*self.exp
return rp*cos(tp), rp*sin(tp)
elif self.base is S.Exp1:
from ..functions import exp
re_e, im_e = self.exp.as_real_imag()
if deep:
re_e = re_e.expand(deep, **hints)
im_e = im_e.expand(deep, **hints)
c, s = cos(im_e), sin(im_e)
return exp(re_e)*c, exp(re_e)*s
else:
if deep:
hints['complex'] = False
expanded = self.expand(deep, **hints)
if hints.get('ignore') == expanded:
return None
else:
return (re(expanded), im(expanded))
else:
return re(self), im(self)
def _eval_derivative(self, s):
from sympy import log
dbase = self.base.diff(s)
dexp = self.exp.diff(s)
return self * (dexp * log(self.base) + dbase * self.exp/self.base)
def _eval_evalf(self, prec):
base, exp = self.as_base_exp()
if base == S.Exp1:
# Use mpmath function associated to class "exp":
from sympy import exp as exp_function
return exp_function(self.exp, evaluate=False)._eval_evalf(prec)
base = base._evalf(prec)
if not exp.is_Integer:
exp = exp._evalf(prec)
if exp.is_negative and base.is_number and base.is_extended_real is False:
base = base.conjugate() / (base * base.conjugate())._evalf(prec)
exp = -exp
return self.func(base, exp).expand()
return self.func(base, exp)
def _eval_is_polynomial(self, syms):
if self.exp.has(*syms):
return False
if self.base.has(*syms):
return bool(self.base._eval_is_polynomial(syms) and
self.exp.is_Integer and (self.exp >= 0))
else:
return True
def _eval_is_rational(self):
# The evaluation of self.func below can be very expensive in the case
# of integer**integer if the exponent is large. We should try to exit
# before that if possible:
if (self.exp.is_integer and self.base.is_rational
and fuzzy_not(fuzzy_and([self.exp.is_negative, self.base.is_zero]))):
return True
p = self.func(*self.as_base_exp()) # in case it's unevaluated
if not p.is_Pow:
return p.is_rational
b, e = p.as_base_exp()
if e.is_Rational and b.is_Rational:
# we didn't check that e is not an Integer
# because Rational**Integer autosimplifies
return False
if e.is_integer:
if b.is_rational:
if fuzzy_not(b.is_zero) or e.is_nonnegative:
return True
if b == e: # always rational, even for 0**0
return True
elif b.is_irrational:
return e.is_zero
if b is S.Exp1:
if e.is_rational and e.is_nonzero:
return False
def _eval_is_algebraic(self):
def _is_one(expr):
try:
return (expr - 1).is_zero
except ValueError:
# when the operation is not allowed
return False
if self.base.is_zero or _is_one(self.base):
return True
elif self.base is S.Exp1:
s = self.func(*self.args)
if s.func == self.func:
if self.exp.is_nonzero:
if self.exp.is_algebraic:
return False
elif (self.exp/S.Pi).is_rational:
return False
elif (self.exp/(S.ImaginaryUnit*S.Pi)).is_rational:
return True
else:
return s.is_algebraic
elif self.exp.is_rational:
if self.base.is_algebraic is False:
return self.exp.is_zero
if self.base.is_zero is False:
if self.exp.is_nonzero:
return self.base.is_algebraic
elif self.base.is_algebraic:
return True
if self.exp.is_positive:
return self.base.is_algebraic
elif self.base.is_algebraic and self.exp.is_algebraic:
if ((fuzzy_not(self.base.is_zero)
and fuzzy_not(_is_one(self.base)))
or self.base.is_integer is False
or self.base.is_irrational):
return self.exp.is_rational
def _eval_is_rational_function(self, syms):
if self.exp.has(*syms):
return False
if self.base.has(*syms):
return self.base._eval_is_rational_function(syms) and \
self.exp.is_Integer
else:
return True
def _eval_is_meromorphic(self, x, a):
# f**g is meromorphic if g is an integer and f is meromorphic.
# E**(log(f)*g) is meromorphic if log(f)*g is meromorphic
# and finite.
base_merom = self.base._eval_is_meromorphic(x, a)
exp_integer = self.exp.is_Integer
if exp_integer:
return base_merom
exp_merom = self.exp._eval_is_meromorphic(x, a)
if base_merom is False:
# f**g = E**(log(f)*g) may be meromorphic if the
# singularities of log(f) and g cancel each other,
# for example, if g = 1/log(f). Hence,
return False if exp_merom else None
elif base_merom is None:
return None
b = self.base.subs(x, a)
# b is extended complex as base is meromorphic.
# log(base) is finite and meromorphic when b != 0, zoo.
b_zero = b.is_zero
if b_zero:
log_defined = False
else:
log_defined = fuzzy_and((b.is_finite, fuzzy_not(b_zero)))
if log_defined is False: # zero or pole of base
return exp_integer # False or None
elif log_defined is None:
return None
if not exp_merom:
return exp_merom # False or None
return self.exp.subs(x, a).is_finite
def _eval_is_algebraic_expr(self, syms):
if self.exp.has(*syms):
return False
if self.base.has(*syms):
return self.base._eval_is_algebraic_expr(syms) and \
self.exp.is_Rational
else:
return True
def _eval_rewrite_as_exp(self, base, expo, **kwargs):
from sympy import exp, log, I, arg
if base.is_zero or base.has(exp) or expo.has(exp):
return base**expo
if base.has(Symbol):
# delay evaluation if expo is non symbolic
# (as exp(x*log(5)) automatically reduces to x**5)
if global_parameters.exp_is_pow:
return Pow(S.Exp1, log(base)*expo, evaluate=expo.has(Symbol))
else:
return exp(log(base)*expo, evaluate=expo.has(Symbol))
else:
return exp((log(abs(base)) + I*arg(base))*expo)
def as_numer_denom(self):
if not self.is_commutative:
return self, S.One
base, exp = self.as_base_exp()
n, d = base.as_numer_denom()
# this should be the same as ExpBase.as_numer_denom wrt
# exponent handling
neg_exp = exp.is_negative
if not neg_exp and not (-exp).is_negative:
neg_exp = _coeff_isneg(exp)
int_exp = exp.is_integer
# the denominator cannot be separated from the numerator if
# its sign is unknown unless the exponent is an integer, e.g.
# sqrt(a/b) != sqrt(a)/sqrt(b) when a=1 and b=-1. But if the
# denominator is negative the numerator and denominator can
# be negated and the denominator (now positive) separated.
if not (d.is_extended_real or int_exp):
n = base
d = S.One
dnonpos = d.is_nonpositive
if dnonpos:
n, d = -n, -d
elif dnonpos is None and not int_exp:
n = base
d = S.One
if neg_exp:
n, d = d, n
exp = -exp
if exp.is_infinite:
if n is S.One and d is not S.One:
return n, self.func(d, exp)
if n is not S.One and d is S.One:
return self.func(n, exp), d
return self.func(n, exp), self.func(d, exp)
def matches(self, expr, repl_dict={}, old=False):
expr = _sympify(expr)
repl_dict = repl_dict.copy()
# special case, pattern = 1 and expr.exp can match to 0
if expr is S.One:
d = self.exp.matches(S.Zero, repl_dict)
if d is not None:
return d
# make sure the expression to be matched is an Expr
if not isinstance(expr, Expr):
return None
b, e = expr.as_base_exp()
# special case number
sb, se = self.as_base_exp()
if sb.is_Symbol and se.is_Integer and expr:
if e.is_rational:
return sb.matches(b**(e/se), repl_dict)
return sb.matches(expr**(1/se), repl_dict)
d = repl_dict.copy()
d = self.base.matches(b, d)
if d is None:
return None
d = self.exp.xreplace(d).matches(e, d)
if d is None:
return Expr.matches(self, expr, repl_dict)
return d
def _eval_nseries(self, x, n, logx, cdir=0):
# NOTE! This function is an important part of the gruntz algorithm
# for computing limits. It has to return a generalized power
# series with coefficients in C(log, log(x)). In more detail:
# It has to return an expression
# c_0*x**e_0 + c_1*x**e_1 + ... (finitely many terms)
# where e_i are numbers (not necessarily integers) and c_i are
# expressions involving only numbers, the log function, and log(x).
# The series expansion of b**e is computed as follows:
# 1) We express b as f*(1 + g) where f is the leading term of b.
# g has order O(x**d) where d is strictly positive.
# 2) Then b**e = (f**e)*((1 + g)**e).
# (1 + g)**e is computed using binomial series.
from sympy import im, I, ceiling, polygamma, logcombine, EulerGamma, nan, zoo, factorial, ff, PoleError, O, powdenest, Wild
from itertools import product
from ..functions import exp, log
from ..series import Order, limit
from ..simplify import powsimp
if self.base is S.Exp1:
e_series = self.exp.nseries(x, n=n, logx=logx)
if e_series.is_Order:
return 1 + e_series
e0 = limit(e_series.removeO(), x, 0)
if e0 is S.NegativeInfinity:
return Order(x**n, x)
if e0 is S.Infinity:
return self
t = e_series - e0
exp_series = term = exp(e0)
# series of exp(e0 + t) in t
for i in range(1, n):
term *= t/i
term = term.nseries(x, n=n, logx=logx)
exp_series += term
exp_series += Order(t**n, x)
return powsimp(exp_series, deep=True, combine='exp')
self = powdenest(self, force=True).trigsimp()
b, e = self.as_base_exp()
if e.has(S.Infinity, S.NegativeInfinity, S.ComplexInfinity, S.NaN):
raise PoleError()
if e.has(x):
return exp(e*log(b))._eval_nseries(x, n=n, logx=logx, cdir=cdir)
if logx is not None and b.has(log):
c, ex = symbols('c, ex', cls=Wild, exclude=[x])
b = b.replace(log(c*x**ex), log(c) + ex*logx)
self = b**e
b = b.removeO()
try:
if b.has(polygamma, EulerGamma) and logx is not None:
raise ValueError()
_, m = b.leadterm(x)
except (ValueError, NotImplementedError, PoleError):
b = b._eval_nseries(x, n=max(2, n), logx=logx, cdir=cdir).removeO()
if b.has(nan, zoo):
raise NotImplementedError()
_, m = b.leadterm(x)
if e.has(log):
e = logcombine(e).cancel()
if not (m.is_zero or e.is_number and e.is_real):
return exp(e*log(b))._eval_nseries(x, n=n, logx=logx, cdir=cdir)
f = b.as_leading_term(x, logx=logx)
g = (b/f - S.One).cancel(expand=False)
if not m.is_number:
raise NotImplementedError()
maxpow = n - m*e
if maxpow.is_negative:
return O(x**(m*e), x)
if g.is_zero:
r = f**e
if r != self:
r += Order(x**n, x)
return r
def coeff_exp(term, x):
coeff, exp = S.One, S.Zero
for factor in Mul.make_args(term):
if factor.has(x):
base, exp = factor.as_base_exp()
if base != x:
try:
return term.leadterm(x)
except ValueError:
return term, S.Zero
else:
coeff *= factor
return coeff, exp
def mul(d1, d2):
res = {}
for e1, e2 in product(d1, d2):
ex = e1 + e2
if ex < maxpow:
res[ex] = res.get(ex, S.Zero) + d1[e1]*d2[e2]
return res
try:
_, d = g.leadterm(x)
except (ValueError, NotImplementedError):
if limit(g/x**maxpow, x, 0) == 0:
# g has higher order zero
return f**e + e*f**e*g # first term of binomial series
else:
raise NotImplementedError()
if not d.is_positive:
g = g.simplify()
_, d = g.leadterm(x)
if not d.is_positive:
raise NotImplementedError()
gpoly = g._eval_nseries(x, n=ceiling(maxpow), logx=logx, cdir=cdir).removeO()
gterms = {}
for term in Add.make_args(gpoly):
co1, e1 = coeff_exp(term, x)
gterms[e1] = gterms.get(e1, S.Zero) + co1
k = S.One
terms = {S.Zero: S.One}
tk = gterms
while (k*d - maxpow).is_negative:
coeff = ff(e, k)/factorial(k)
for ex in tk:
terms[ex] = terms.get(ex, S.Zero) + coeff*tk[ex]
tk = mul(tk, gterms)
k += S.One
if (not e.is_integer and m.is_zero and f.is_real
and f.is_negative and im((b - f).dir(x, cdir)).is_negative):
inco, inex = coeff_exp(f**e*exp(-2*e*S.Pi*I), x)
else:
inco, inex = coeff_exp(f**e, x)
res = S.Zero
for e1 in terms:
ex = e1 + inex
res += terms[e1]*inco*x**(ex)
if not (e.is_integer and e.is_positive and (e*d - n).is_nonpositive and
res == _mexpand(self)):
res += O(x**n, x)
return res
def _eval_as_leading_term(self, x, logx=None, cdir=0):
from sympy import exp, I, im, log, PoleError
e = self.exp
b = self.base
if self.base is S.Exp1:
arg = e.as_leading_term(x, logx=logx)
arg0 = arg.subs(x, 0)
if arg0 is S.NaN:
arg0 = arg.limit(x, 0)
if arg0.is_infinite is False:
return S.Exp1**arg0
raise PoleError("Cannot expand %s around 0" % (self))
elif e.has(x):
lt = exp(e * log(b))
try:
lt = lt.as_leading_term(x, logx=logx, cdir=cdir)
except PoleError:
pass
return lt
else:
f = b.as_leading_term(x, logx=logx, cdir=cdir)
if (not e.is_integer and f.is_constant() and f.is_real
and f.is_negative and im((b - f).dir(x, cdir)).is_negative):
return self.func(f, e) * exp(-2 * e * S.Pi * I)
return self.func(f, e)
@cacheit
def _taylor_term(self, n, x, *previous_terms): # of (1 + x)**e
from sympy import binomial
return binomial(self.exp, n) * self.func(x, n)
def taylor_term(self, n, x, *previous_terms):
if self.base is not S.Exp1:
return super().taylor_term(n, x, *previous_terms)
from sympy import sympify, factorial
if n < 0:
return S.Zero
if n == 0:
return S.One
x = sympify(x)
if previous_terms:
p = previous_terms[-1]
if p is not None:
return p * x / n
return x**n/factorial(n)
def _sage_(self):
return self.args[0]._sage_()**self.args[1]._sage_()
def _eval_rewrite_as_sin(self, base, exp):
from ..functions import sin
if self.base is S.Exp1:
return sin(S.ImaginaryUnit*self.exp + S.Pi/2) - S.ImaginaryUnit*sin(S.ImaginaryUnit*self.exp)
def _eval_rewrite_as_cos(self, base, exp):
from ..functions import cos
if self.base is S.Exp1:
return cos(S.ImaginaryUnit*self.exp) + S.ImaginaryUnit*cos(S.ImaginaryUnit*self.exp + S.Pi/2)
def _eval_rewrite_as_tanh(self, base, exp):
from ..functions import tanh
if self.base is S.Exp1:
return (1 + tanh(self.exp/2))/(1 - tanh(self.exp/2))
def _eval_rewrite_as_sqrt(self, base, exp, **kwargs):
from sympy.functions.elementary.trigonometric import sin, cos
if base is not S.Exp1:
return None
if exp.is_Mul:
coeff = exp.coeff(S.Pi * S.ImaginaryUnit)
if coeff and coeff.is_number:
cosine, sine = cos(S.Pi*coeff), sin(S.Pi*coeff)
if not isinstance(cosine, cos) and not isinstance (sine, sin):
return cosine + S.ImaginaryUnit*sine
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 sqrt
>>> sqrt(4 + 4*sqrt(2)).as_content_primitive()
(2, sqrt(1 + sqrt(2)))
>>> sqrt(3 + 3*sqrt(2)).as_content_primitive()
(1, sqrt(3)*sqrt(1 + sqrt(2)))
>>> from sympy import expand_power_base, powsimp, Mul
>>> from sympy.abc import x, y
>>> ((2*x + 2)**2).as_content_primitive()
(4, (x + 1)**2)
>>> (4**((1 + y)/2)).as_content_primitive()
(2, 4**(y/2))
>>> (3**((1 + y)/2)).as_content_primitive()
(1, 3**((y + 1)/2))
>>> (3**((5 + y)/2)).as_content_primitive()
(9, 3**((y + 1)/2))
>>> eq = 3**(2 + 2*x)
>>> powsimp(eq) == eq
True
>>> eq.as_content_primitive()
(9, 3**(2*x))
>>> powsimp(Mul(*_))
3**(2*x + 2)
>>> eq = (2 + 2*x)**y
>>> s = expand_power_base(eq); s.is_Mul, s
(False, (2*x + 2)**y)
>>> eq.as_content_primitive()
(1, (2*(x + 1))**y)
>>> s = expand_power_base(_[1]); s.is_Mul, s
(True, 2**y*(x + 1)**y)
See docstring of Expr.as_content_primitive for more examples.
"""
b, e = self.as_base_exp()
b = _keep_coeff(*b.as_content_primitive(radical=radical, clear=clear))
ce, pe = e.as_content_primitive(radical=radical, clear=clear)
if b.is_Rational:
#e
#= ce*pe
#= ce*(h + t)
#= ce*h + ce*t
#=> self
#= b**(ce*h)*b**(ce*t)
#= b**(cehp/cehq)*b**(ce*t)
#= b**(iceh + r/cehq)*b**(ce*t)
#= b**(iceh)*b**(r/cehq)*b**(ce*t)
#= b**(iceh)*b**(ce*t + r/cehq)
h, t = pe.as_coeff_Add()
if h.is_Rational:
ceh = ce*h
c = self.func(b, ceh)
r = S.Zero
if not c.is_Rational:
iceh, r = divmod(ceh.p, ceh.q)
c = self.func(b, iceh)
return c, self.func(b, _keep_coeff(ce, t + r/ce/ceh.q))
e = _keep_coeff(ce, pe)
# b**e = (h*t)**e = h**e*t**e = c*m*t**e
if e.is_Rational and b.is_Mul:
h, t = b.as_content_primitive(radical=radical, clear=clear) # h is positive
c, m = self.func(h, e).as_coeff_Mul() # so c is positive
m, me = m.as_base_exp()
if m is S.One or me == e: # probably always true
# return the following, not return c, m*Pow(t, e)
# which would change Pow into Mul; we let sympy
# decide what to do by using the unevaluated Mul, e.g
# should it stay as sqrt(2 + 2*sqrt(5)) or become
# sqrt(2)*sqrt(1 + sqrt(5))
return c, self.func(_keep_coeff(m, t), e)
return S.One, self.func(b, e)
def is_constant(self, *wrt, **flags):
expr = self
if flags.get('simplify', True):
expr = expr.simplify()
b, e = expr.as_base_exp()
bz = b.equals(0)
if bz: # recalculate with assumptions in case it's unevaluated
new = b**e
if new != expr:
return new.is_constant()
econ = e.is_constant(*wrt)
bcon = b.is_constant(*wrt)
if bcon:
if econ:
return True
bz = b.equals(0)
if bz is False:
return False
elif bcon is None:
return None
return e.equals(0)
def _eval_difference_delta(self, n, step):
b, e = self.args
if e.has(n) and not b.has(n):
new_e = e.subs(n, n + step)
return (b**(new_e - e) - 1) * self
power = Dispatcher('power')
power.add((object, object), Pow)
from .add import Add
from .numbers import Integer
from .mul import Mul, _keep_coeff
from .symbol import Symbol, Dummy, symbols
|
09db3c48395a1b5a92eb97fe97e225e11901a2bcfd80580e884a57fa07d762ba | """Tools for manipulating of large commutative expressions. """
from sympy.core.add import Add
from sympy.core.compatibility import iterable, is_sequence, SYMPY_INTS
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
>>> 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_extended_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_extended_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_extended_nonpositive or s.is_extended_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_extended_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.One
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.
Explanation
===========
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:
"""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())
# Handle all rational Coefficients
for f in list(factors.keys()):
if isinstance(f, Rational) and not isinstance(f, Integer):
p, q = Integer(f.p), Integer(f.q)
factors[p] = (factors[p] if p in factors else S.Zero) + factors[f]
factors[q] = (factors[q] if q in factors else S.Zero) - factors[f]
factors.pop(f)
if i:
factors[I] = factors.get(I, S.Zero) + 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:
factors[a.base] = factors.get(a.base, S.Zero) + 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
keys = getattr(factors, 'keys', None)
if keys is None:
raise TypeError('expecting Expr or dictionary')
self.gens = frozenset(keys())
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:
if isinstance(exp, Integer):
b, e = factor.as_base_exp()
e = _keep_coeff(exp, e)
args.append(b**e)
else:
args.append(factor**exp)
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 __truediv__(self, other): # Factors
return self.quo(other)
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:
"""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 __truediv__(self, other): # Term
if isinstance(other, Term):
return self.quo(other)
else:
return NotImplemented
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`.
Parameters
==========
isprimitive : boolean, optional
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.
fraction : boolean, optional
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.One).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.
Parameters
==========
terms : Expr
Can be an expression or a non-Basic sequence of expressions
which will be handled as though they are terms from a sum.
isprimitive : bool, optional
If ``isprimitive`` is True the _gcd_terms will not run the primitive
method on the terms.
clear : bool, optional
It 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 : bool, optional
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(*nc)
d = Dummy()
reps.append((d, nc))
c.append(d)
args[i] = Mul(*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):
if not a.args:
return a
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_sum_int(expr, **kwargs):
"""Return Sum or Integral object with factors that are not
in the wrt variables removed. In cases where there are additive
terms in the function of the object that are independent, the
object will be separated into two objects.
Examples
========
>>> from sympy import Sum, factor_terms
>>> from sympy.abc import x, y
>>> factor_terms(Sum(x + y, (x, 1, 3)))
y*Sum(1, (x, 1, 3)) + Sum(x, (x, 1, 3))
>>> factor_terms(Sum(x*y, (x, 1, 3)))
y*Sum(x, (x, 1, 3))
Notes
=====
If a function in the summand or integrand is replaced
with a symbol, then this simplification should not be
done or else an incorrect result will be obtained when
the symbol is replaced with an expression that depends
on the variables of summation/integration:
>>> eq = Sum(y, (x, 1, 3))
>>> factor_terms(eq).subs(y, x).doit()
3*x
>>> eq.subs(y, x).doit()
6
"""
result = expr.function
if result == 0:
return S.Zero
limits = expr.limits
# get the wrt variables
wrt = {i.args[0] for i in limits}
# factor out any common terms that are independent of wrt
f = factor_terms(result, **kwargs)
i, d = f.as_independent(*wrt)
if isinstance(f, Add):
return i * expr.func(1, *limits) + expr.func(d, *limits)
else:
return i * expr.func(d, *limits)
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.
Parameters
==========
radical: bool, optional
If radical=True then a radical common to all terms will be factored
out of any Add sub-expressions of the expr.
clear : bool, optional
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.
fraction : bool, optional
If fraction=True (default is False) then a common denominator will be
constructed for the expression.
sign : bool, optional
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.integrals.integrals import Integral
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, Integral)):
return _factor_sum_int(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.
Explanation
===========
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.
Parameters
==========
name : str
``name``, if given, is the name that will be used with numbered Dummy
variables that will replace the non-commutative objects and is mainly
used for doctesting purposes.
Examples
========
>>> from sympy.physics.secondquant import Commutator, NO, F, Fd
>>> from sympy import symbols
>>> 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])
"""
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 _ in args:
_[1][0] = il*_[1][0]
break
if not ok:
break
else:
hit = True
lenn = len(n)
l = Mul(*n)
for _ in args:
_[1] = _[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 _ in args:
_[1][-1] = _[1][-1]*il
break
if not ok:
break
else:
hit = True
lenn = len(n)
r = Mul(*n)
for _ in args:
_[1] = _[1][:len(_[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)
|
961b578cdd8c5e186cb898a99edf2dd757c8e575ce91a7646e1a1eee12914ff6 | """
This module contains the machinery handling assumptions.
All symbolic objects have assumption attributes that can be accessed via
.is_<assumption name> attribute.
Assumptions determine certain properties of symbolic objects and can
have 3 possible values: True, False, None. True is returned if the
object has the property and False is returned if it doesn't or can't
(i.e. doesn't make sense):
>>> from sympy import I
>>> I.is_algebraic
True
>>> I.is_real
False
>>> I.is_prime
False
When the property cannot be determined (or when a method is not
implemented) None will be returned, e.g. a generic symbol, x, may or
may not be positive so a value of None is returned for x.is_positive.
By default, all symbolic values are in the largest set in the given context
without specifying the property. For example, a symbol that has a property
being integer, is also real, complex, etc.
Here follows a list of possible assumption names:
.. glossary::
commutative
object commutes with any other object with
respect to multiplication operation.
complex
object can have only values from the set
of complex numbers.
imaginary
object value is a number that can be written as a real
number multiplied by the imaginary unit ``I``. See
[3]_. Please note that ``0`` is not considered to be an
imaginary number, see
`issue #7649 <https://github.com/sympy/sympy/issues/7649>`_.
real
object can have only values from the set
of real numbers.
integer
object can have only values from the set
of integers.
odd
even
object can have only values from the set of
odd (even) integers [2]_.
prime
object is a natural number greater than ``1`` that has
no positive divisors other than ``1`` and itself. See [6]_.
composite
object is a positive integer that has at least one positive
divisor other than ``1`` or the number itself. See [4]_.
zero
object has the value of ``0``.
nonzero
object is a real number that is not zero.
rational
object can have only values from the set
of rationals.
algebraic
object can have only values from the set
of algebraic numbers [11]_.
transcendental
object can have only values from the set
of transcendental numbers [10]_.
irrational
object value cannot be represented exactly by Rational, see [5]_.
finite
infinite
object absolute value is bounded (arbitrarily large).
See [7]_, [8]_, [9]_.
negative
nonnegative
object can have only negative (nonnegative)
values [1]_.
positive
nonpositive
object can have only positive (only
nonpositive) values.
hermitian
antihermitian
object belongs to the field of hermitian
(antihermitian) operators.
Examples
========
>>> from sympy import Symbol
>>> x = Symbol('x', real=True); x
x
>>> x.is_real
True
>>> x.is_complex
True
See Also
========
.. seealso::
:py:class:`sympy.core.numbers.ImaginaryUnit`
:py:class:`sympy.core.numbers.Zero`
:py:class:`sympy.core.numbers.One`
Notes
=====
The fully-resolved assumptions for any SymPy expression
can be obtained as follows:
>>> from sympy.core.assumptions import assumptions
>>> x = Symbol('x',positive=True)
>>> assumptions(x + I)
{'commutative': True, 'complex': True, 'composite': False, 'even':
False, 'extended_negative': False, 'extended_nonnegative': False,
'extended_nonpositive': False, 'extended_nonzero': False,
'extended_positive': False, 'extended_real': False, 'finite': True,
'imaginary': False, 'infinite': False, 'integer': False, 'irrational':
False, 'negative': False, 'noninteger': False, 'nonnegative': False,
'nonpositive': False, 'nonzero': False, 'odd': False, 'positive':
False, 'prime': False, 'rational': False, 'real': False, 'zero':
False}
Developers Notes
================
The current (and possibly incomplete) values are stored
in the ``obj._assumptions dictionary``; queries to getter methods
(with property decorators) or attributes of objects/classes
will return values and update the dictionary.
>>> eq = x**2 + I
>>> eq._assumptions
{}
>>> eq.is_finite
True
>>> eq._assumptions
{'finite': True, 'infinite': False}
For a Symbol, there are two locations for assumptions that may
be of interest. The ``assumptions0`` attribute gives the full set of
assumptions derived from a given set of initial assumptions. The
latter assumptions are stored as ``Symbol._assumptions.generator``
>>> Symbol('x', prime=True, even=True)._assumptions.generator
{'even': True, 'prime': True}
The ``generator`` is not necessarily canonical nor is it filtered
in any way: it records the assumptions used to instantiate a Symbol
and (for storage purposes) represents a more compact representation
of the assumptions needed to recreate the full set in
`Symbol.assumptions0`.
References
==========
.. [1] https://en.wikipedia.org/wiki/Negative_number
.. [2] https://en.wikipedia.org/wiki/Parity_%28mathematics%29
.. [3] https://en.wikipedia.org/wiki/Imaginary_number
.. [4] https://en.wikipedia.org/wiki/Composite_number
.. [5] https://en.wikipedia.org/wiki/Irrational_number
.. [6] https://en.wikipedia.org/wiki/Prime_number
.. [7] https://en.wikipedia.org/wiki/Finite
.. [8] https://docs.python.org/3/library/math.html#math.isfinite
.. [9] http://docs.scipy.org/doc/numpy/reference/generated/numpy.isfinite.html
.. [10] https://en.wikipedia.org/wiki/Transcendental_number
.. [11] https://en.wikipedia.org/wiki/Algebraic_number
"""
from sympy.core.facts import FactRules, FactKB
from sympy.core.core import BasicMeta
from sympy.core.sympify import sympify
from random import shuffle
_assume_rules = FactRules([
'integer -> rational',
'rational -> real',
'rational -> algebraic',
'algebraic -> complex',
'transcendental == complex & !algebraic',
'real -> hermitian',
'imaginary -> complex',
'imaginary -> antihermitian',
'extended_real -> commutative',
'complex -> commutative',
'complex -> finite',
'odd == integer & !even',
'even == integer & !odd',
'real -> complex',
'extended_real -> real | infinite',
'real == extended_real & finite',
'extended_real == extended_negative | zero | extended_positive',
'extended_negative == extended_nonpositive & extended_nonzero',
'extended_positive == extended_nonnegative & extended_nonzero',
'extended_nonpositive == extended_real & !extended_positive',
'extended_nonnegative == extended_real & !extended_negative',
'real == negative | zero | positive',
'negative == nonpositive & nonzero',
'positive == nonnegative & nonzero',
'nonpositive == real & !positive',
'nonnegative == real & !negative',
'positive == extended_positive & finite',
'negative == extended_negative & finite',
'nonpositive == extended_nonpositive & finite',
'nonnegative == extended_nonnegative & finite',
'nonzero == extended_nonzero & finite',
'zero -> even & finite',
'zero == extended_nonnegative & extended_nonpositive',
'zero == nonnegative & nonpositive',
'nonzero -> real',
'prime -> integer & positive',
'composite -> integer & positive & !prime',
'!composite -> !positive | !even | prime',
'irrational == real & !rational',
'imaginary -> !extended_real',
'infinite == !finite',
'noninteger == extended_real & !integer',
'extended_nonzero == extended_real & !zero',
])
_assume_defined = _assume_rules.defined_facts.copy()
_assume_defined.add('polar')
_assume_defined = frozenset(_assume_defined)
def assumptions(expr, _check=None):
"""return the T/F assumptions of ``expr``"""
n = sympify(expr)
if n.is_Symbol:
rv = n.assumptions0 # are any important ones missing?
if _check is not None:
rv = {k: rv[k] for k in set(rv) & set(_check)}
return rv
rv = {}
for k in _assume_defined if _check is None else _check:
v = getattr(n, 'is_{}'.format(k))
if v is not None:
rv[k] = v
return rv
def common_assumptions(exprs, check=None):
"""return those assumptions which have the same True or False
value for all the given expressions.
Examples
========
>>> from sympy.core.assumptions import common_assumptions
>>> from sympy import oo, pi, sqrt
>>> common_assumptions([-4, 0, sqrt(2), 2, pi, oo])
{'commutative': True, 'composite': False,
'extended_real': True, 'imaginary': False, 'odd': False}
By default, all assumptions are tested; pass an iterable of the
assumptions to limit those that are reported:
>>> common_assumptions([0, 1, 2], ['positive', 'integer'])
{'integer': True}
"""
check = _assume_defined if check is None else set(check)
if not check or not exprs:
return {}
# get all assumptions for each
assume = [assumptions(i, _check=check) for i in sympify(exprs)]
# focus on those of interest that are True
for i, e in enumerate(assume):
assume[i] = {k: e[k] for k in set(e) & check}
# what assumptions are in common?
common = set.intersection(*[set(i) for i in assume])
# which ones hold the same value
a = assume[0]
return {k: a[k] for k in common if all(a[k] == b[k]
for b in assume)}
def failing_assumptions(expr, **assumptions):
"""
Return a dictionary containing assumptions with values not
matching those of the passed assumptions.
Examples
========
>>> from sympy import failing_assumptions, Symbol
>>> x = Symbol('x', real=True, positive=True)
>>> y = Symbol('y')
>>> failing_assumptions(6*x + y, real=True, positive=True)
{'positive': None, 'real': None}
>>> failing_assumptions(x**2 - 1, positive=True)
{'positive': None}
If *expr* satisfies all of the assumptions, an empty dictionary is returned.
>>> failing_assumptions(x**2, positive=True)
{}
"""
expr = sympify(expr)
failed = {}
for k in assumptions:
test = getattr(expr, 'is_%s' % k, None)
if test is not assumptions[k]:
failed[k] = test
return failed # {} or {assumption: value != desired}
def check_assumptions(expr, against=None, **assume):
"""
Checks whether assumptions of ``expr`` match the T/F assumptions
given (or possessed by ``against``). True is returned if all
assumptions match; False is returned if there is a mismatch and
the assumption in ``expr`` is not None; else None is returned.
Explanation
===========
*assume* is a dict of assumptions with True or False values
Examples
========
>>> from sympy import Symbol, pi, I, exp, check_assumptions
>>> check_assumptions(-5, integer=True)
True
>>> check_assumptions(pi, real=True, integer=False)
True
>>> check_assumptions(pi, real=True, negative=True)
False
>>> check_assumptions(exp(I*pi/7), real=False)
True
>>> x = Symbol('x', real=True, positive=True)
>>> check_assumptions(2*x + 1, real=True, positive=True)
True
>>> check_assumptions(-2*x - 5, real=True, positive=True)
False
To check assumptions of *expr* against another variable or expression,
pass the expression or variable as ``against``.
>>> check_assumptions(2*x + 1, x)
True
To see if a number matches the assumptions of an expression, pass
the number as the first argument, else its specific assumptions
may not have a non-None value in the expression:
>>> check_assumptions(x, 3)
>>> check_assumptions(3, x)
True
``None`` is returned if ``check_assumptions()`` could not conclude.
>>> check_assumptions(2*x - 1, x)
>>> z = Symbol('z')
>>> check_assumptions(z, real=True)
See Also
========
failing_assumptions
"""
expr = sympify(expr)
if against is not None:
if assume:
raise ValueError(
'Expecting `against` or `assume`, not both.')
assume = assumptions(against)
known = True
for k, v in assume.items():
if v is None:
continue
e = getattr(expr, 'is_' + k, None)
if e is None:
known = None
elif v != e:
return False
return known
class StdFactKB(FactKB):
"""A FactKB specialized for the built-in rules
This is the only kind of FactKB that Basic objects should use.
"""
def __init__(self, facts=None):
super().__init__(_assume_rules)
# save a copy of the facts dict
if not facts:
self._generator = {}
elif not isinstance(facts, FactKB):
self._generator = facts.copy()
else:
self._generator = facts.generator
if facts:
self.deduce_all_facts(facts)
def copy(self):
return self.__class__(self)
@property
def generator(self):
return self._generator.copy()
def as_property(fact):
"""Convert a fact name to the name of the corresponding property"""
return 'is_%s' % fact
def make_property(fact):
"""Create the automagic property corresponding to a fact."""
def getit(self):
try:
return self._assumptions[fact]
except KeyError:
if self._assumptions is self.default_assumptions:
self._assumptions = self.default_assumptions.copy()
return _ask(fact, self)
getit.func_name = as_property(fact)
return property(getit)
def _ask(fact, obj):
"""
Find the truth value for a property of an object.
This function is called when a request is made to see what a fact
value is.
For this we use several techniques:
First, the fact-evaluation function is tried, if it exists (for
example _eval_is_integer). Then we try related facts. For example
rational --> integer
another example is joined rule:
integer & !odd --> even
so in the latter case if we are looking at what 'even' value is,
'integer' and 'odd' facts will be asked.
In all cases, when we settle on some fact value, its implications are
deduced, and the result is cached in ._assumptions.
"""
assumptions = obj._assumptions
handler_map = obj._prop_handler
# Store None into the assumptions so that recursive attempts at
# evaluating the same fact don't trigger infinite recursion.
assumptions._tell(fact, None)
# First try the assumption evaluation function if it exists
try:
evaluate = handler_map[fact]
except KeyError:
pass
else:
a = evaluate(obj)
if a is not None:
assumptions.deduce_all_facts(((fact, a),))
return a
# Try assumption's prerequisites
prereq = list(_assume_rules.prereq[fact])
shuffle(prereq)
for pk in prereq:
if pk in assumptions:
continue
if pk in handler_map:
_ask(pk, obj)
# we might have found the value of fact
ret_val = assumptions.get(fact)
if ret_val is not None:
return ret_val
# Note: the result has already been cached
return None
class ManagedProperties(BasicMeta):
"""Metaclass for classes with old-style assumptions"""
def __init__(cls, *args, **kws):
BasicMeta.__init__(cls, *args, **kws)
local_defs = {}
for k in _assume_defined:
attrname = as_property(k)
v = cls.__dict__.get(attrname, '')
if isinstance(v, (bool, int, type(None))):
if v is not None:
v = bool(v)
local_defs[k] = v
defs = {}
for base in reversed(cls.__bases__):
assumptions = getattr(base, '_explicit_class_assumptions', None)
if assumptions is not None:
defs.update(assumptions)
defs.update(local_defs)
cls._explicit_class_assumptions = defs
cls.default_assumptions = StdFactKB(defs)
cls._prop_handler = {}
for k in _assume_defined:
eval_is_meth = getattr(cls, '_eval_is_%s' % k, None)
if eval_is_meth is not None:
cls._prop_handler[k] = eval_is_meth
# Put definite results directly into the class dict, for speed
for k, v in cls.default_assumptions.items():
setattr(cls, as_property(k), v)
# protection e.g. for Integer.is_even=F <- (Rational.is_integer=F)
derived_from_bases = set()
for base in cls.__bases__:
default_assumptions = getattr(base, 'default_assumptions', None)
# is an assumption-aware class
if default_assumptions is not None:
derived_from_bases.update(default_assumptions)
for fact in derived_from_bases - set(cls.default_assumptions):
pname = as_property(fact)
if pname not in cls.__dict__:
setattr(cls, pname, make_property(fact))
# Finally, add any missing automagic property (e.g. for Basic)
for fact in _assume_defined:
pname = as_property(fact)
if not hasattr(cls, pname):
setattr(cls, pname, make_property(fact))
|
87396ece17f41643451156f1620941aa26b42c762d2eec6354308482e41e39ed | """
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 typing import Any, Dict as tDict, Optional, Set as tSet, Tuple as tTuple, Union
from .add import Add
from .assumptions import ManagedProperties
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.parameters import global_parameters
from sympy.core.logic import fuzzy_and, fuzzy_or, fuzzy_not, FuzzyBool
from sympy.utilities import default_sort_key
from sympy.utilities.exceptions import SymPyDeprecationWarning
from sympy.utilities.iterables import has_dups, sift
from sympy.utilities.misc import filldedent
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_extended_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]))
class BadSignatureError(TypeError):
'''Raised when a Lambda is created with an invalid signature'''
pass
class BadArgumentsError(TypeError):
'''Raised when a Lambda is called with an incorrect number of arguments'''
pass
# Python 2/3 version that does not raise a Deprecation warning
def arity(cls):
"""Return the arity of the function if it is known, else None.
Explanation
===========
When default values are specified for some arguments, they are
optional and the arity is reported as a tuple of possible values.
Examples
========
>>> from sympy.core.function import arity
>>> from sympy import log
>>> arity(lambda x: x)
1
>>> arity(log)
(1, 2)
>>> arity(lambda *x: sum(x)) is None
True
"""
eval_ = getattr(cls, 'eval', cls)
parameters = inspect.signature(eval_).parameters.items()
if [p for _, p in parameters if p.kind == p.VAR_POSITIONAL]:
return
p_or_k = [p for _, p in parameters if p.kind == p.POSITIONAL_OR_KEYWORD]
# how many have no default and how many have a default value
no, yes = map(len, sift(p_or_k,
lambda p:p.default == p.empty, binary=True))
return no if not yes else tuple(range(no, no + yes + 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', arity(cls)))
if nargs is None and 'nargs' not in cls.__dict__:
for supcls in cls.__mro__:
if hasattr(supcls, '_nargs'):
nargs = supcls._nargs
break
else:
continue
# 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().__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
>>> 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
FiniteSet(1)
>>> Function('f', nargs=(2, 1)).nargs
FiniteSet(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(Basic, metaclass=FunctionClass):
"""
Base class for applied functions.
Explanation
===========
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_parameters.evaluate)
# 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().__new__(cls, *args, **options)
# make nargs uniform here
sentinel = object()
objnargs = getattr(obj, "nargs", sentinel)
if objnargs is not sentinel:
# 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(objnargs):
nargs = tuple(ordered(set(objnargs)))
elif objnargs is not None:
nargs = (as_int(objnargs),)
else:
nargs = None
else:
# 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.
Explanation
===========
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_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, and if function is initialized with a
Symbol, the function inherits the name and assumptions associated with the Symbol:
>>> f_real = Function('f', real=True)
>>> f_real(x).is_real
True
>>> f_real_inherit = Function(Symbol('f', real=True))
>>> f_real_inherit(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_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_parameters.evaluate)
result = super().__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().
Explanation
===========
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
def _eval_evalf(self, prec):
def _get_mpmath_func(fname):
"""Lookup mpmath function based on name"""
if isinstance(self, AppliedUndef):
# Shouldn't lookup in mpmath but might have ._imp_
return None
if not hasattr(mpmath, fname):
from sympy.utilities.lambdify import MPMATH_TRANSLATIONS
fname = MPMATH_TRANSLATIONS.get(fname, None)
if fname is None:
return None
return getattr(mpmath, fname)
_eval_mpmath = getattr(self, '_eval_mpmath', None)
if _eval_mpmath is None:
func = _get_mpmath_func(self.func.__name__)
args = self.args
else:
func, args = _eval_mpmath()
# Fall-back evaluation
if func is None:
imp = getattr(self, '_imp_', None)
if imp is None:
return None
try:
return Float(imp(*[i.evalf(prec) for i in self.args]), prec)
except (TypeError, ValueError):
return None
# 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 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_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_meromorphic(self, x, a):
if not self.args:
return True
if any(arg.has(x) for arg in self.args[1:]):
return False
arg = self.args[0]
if not arg._eval_is_meromorphic(x, a):
return None
return fuzzy_not(type(self).is_singular(arg.subs(x, a)))
_singularities = None # type: Union[FuzzyBool, tTuple[Expr, ...]]
@classmethod
def is_singular(cls, a):
"""
Tests whether the argument is an essential singularity
or a branch point, or the functions is non-holomorphic.
"""
ss = cls._singularities
if ss in (True, None, False):
return ss
return fuzzy_or(a.is_infinite if s is S.ComplexInfinity
else (a - s).is_zero for s in ss)
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, cdir=0):
"""
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.core.symbol import uniquely_named_symbol
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 _ 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
if len(e.args) == 1:
# issue 14411
e = e.func(e.args[0].cancel())
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 = uniquely_named_symbol('xi', self)
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 = (n/cf).ceiling()
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 or not A.is_Symbol:
return _derivative_dispatch(self, A)
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_dispatch(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, logx=None, cdir=0):
"""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, logx=logx) 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))
u = [a.name for a in args if isinstance(a, UndefinedFunction)]
if u:
raise TypeError('Invalid argument: expecting an expression, not UndefinedFunction%s: %s' % (
's'*(len(u) > 1), ', '.join(u)))
obj = super().__new__(cls, *args, **options)
return obj
def _eval_as_leading_term(self, x, logx=None, cdir=0):
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 UndefSageHelper:
"""
Helper to facilitate Sage conversion.
"""
def __get__(self, ins, typ):
import sage.all as sage
if ins is None:
return lambda: sage.function(typ.__name__)
else:
args = [arg._sage_() for arg in ins.args]
return lambda : sage.function(ins.__class__.__name__)(*args)
_undef_sage_helper = UndefSageHelper()
class UndefinedFunction(FunctionClass):
"""
The (meta)class of undefined functions.
"""
def __new__(mcl, name, bases=(AppliedUndef,), __dict__=None, **kwargs):
from .symbol import _filter_assumptions
# Allow Function('f', real=True)
# and/or Function(Symbol('f', real=True))
assumptions, kwargs = _filter_assumptions(kwargs)
if isinstance(name, Symbol):
assumptions = name._merge(assumptions)
name = name.name
elif not isinstance(name, str):
raise TypeError('expecting string or Symbol for name')
else:
commutative = assumptions.get('commutative', None)
assumptions = Symbol(name, **assumptions).assumptions0
if commutative is None:
assumptions.pop('commutative')
__dict__ = __dict__ or {}
# put the `is_*` for into __dict__
__dict__.update({'is_%s' % k: v for k, v in assumptions.items()})
# 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)
# add back the sanitized assumptions without the is_ prefix
kwargs.update(assumptions)
# Save these for __eq__
__dict__.update({'_kwargs': kwargs})
# do this for pickling
__dict__['__module__'] = None
obj = super().__new__(mcl, name, bases, __dict__)
obj.name = name
obj._sage_ = _undef_sage_helper
return obj
def __instancecheck__(cls, instance):
return cls in type(instance).__mro__
_kwargs = {} # type: tDict[str, Optional[bool]]
def __hash__(self):
return hash((self.class_key(), frozenset(self._kwargs.items())))
def __eq__(self, other):
return (isinstance(other, self.__class__) and
self.class_key() == other.class_key() and
self._kwargs == other._kwargs)
def __ne__(self, other):
return not self == other
@property
def _diff_wrt(self):
return False
# XXX: The type: ignore on WildFunction is because mypy complains:
#
# sympy/core/function.py:939: error: Cannot determine type of 'sort_key' in
# base class 'Expr'
#
# Somehow this is because of the @cacheit decorator but it is not clear how to
# fix it.
class WildFunction(Function, AtomicExpr): # type: ignore
"""
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
FiniteSet(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
FiniteSet(1, 2)
>>> f(x).match(F)
{F_: f(x)}
>>> f(x, y).match(F)
{F_: f(x, y)}
>>> f(x, y, 1).match(F)
"""
# XXX: What is this class attribute used for?
include = set() # type: tSet[Any]
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 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 explicitly 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, MatrixExpr
from sympy.tensor.array import Array, NDimArray
from sympy.utilities.misc import filldedent
expr = sympify(expr)
symbols_or_none = getattr(expr, "free_symbols", None)
has_symbol_set = isinstance(symbols_or_none, set)
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 {} followed by number {}".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
elif isinstance(v, UndefinedFunction):
raise TypeError(
"cannot differentiate wrt "
"UndefinedFunction: %s" % v)
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, MatrixExpr):
zero = False
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:
return cls._get_zero_with_shape_like(expr)
# 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_dispatch(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)
obj = cls._dispatch_eval_derivative_n_times(expr, 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
expr = old_expr
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
>>> 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
rv = self.func(expr, *self.variable_count, **hints)
if rv!= self and rv.has(Derivative):
rv = rv.doit(**hints)
return rv
@_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.
"""
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):
ret = self.expr.free_symbols
# Add symbolic counts to free_symbols
for var, count in self.variable_count:
ret.update(count.free_symbols)
return ret
@property
def kind(self):
return self.args[0].kind
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:
# first handle the counts
expr = self.func(self.expr, *[(v, c.subs(old, new))
for v, c in self.variable_count])
if expr != self:
return expr._eval_subs(old, new)
# 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_dispatch(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_dispatch(*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 = {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_dispatch(*newargs)
def _eval_lseries(self, x, logx, cdir=0):
dx = self.variables
for term in self.expr.lseries(x, logx=logx, cdir=cdir):
yield self.func(term, *dx)
def _eval_nseries(self, x, n, logx, cdir=0):
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, logx=None, cdir=0):
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)/...
To approximate ``Derivative`` around ``x0`` using a non-equidistant
spacing step, the algorithm supports assignment of undefined
functions to ``points``:
>>> dx = Function('dx')
>>> f(x).diff(x).as_finite_difference(points=dx(x), x0=x-h)
-f(-h + x - dx(-h + x)/2)/dx(-h + x) + f(-h + x + dx(-h + x)/2)/dx(-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)
@classmethod
def _get_zero_with_shape_like(cls, expr):
return S.Zero
@classmethod
def _dispatch_eval_derivative_n_times(cls, expr, v, count):
# 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`:
return expr._eval_derivative_n_times(v, count)
def _derivative_dispatch(expr, *variables, **kwargs):
from sympy.matrices.common import MatrixCommon
from sympy import MatrixExpr
from sympy import NDimArray
array_types = (MatrixCommon, MatrixExpr, NDimArray, list, tuple, Tuple)
if isinstance(expr, array_types) or any(isinstance(i[0], array_types) if isinstance(i, (tuple, list, Tuple)) else isinstance(i, array_types) for i in variables):
from sympy.tensor.array.array_derivatives import ArrayDerivative
return ArrayDerivative(expr, *variables, **kwargs)
return Derivative(expr, *variables, **kwargs)
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).
Examples
========
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
It is also possible to unpack tuple arguments:
>>> f = Lambda( ((x, y), z) , x + y + z)
>>> f((1, 2), 3)
6
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, signature, expr):
if iterable(signature) and not isinstance(signature, (tuple, Tuple)):
SymPyDeprecationWarning(
feature="non tuple iterable of argument symbols to Lambda",
useinstead="tuple of argument symbols",
issue=17474,
deprecated_since_version="1.5").warn()
signature = tuple(signature)
sig = signature if iterable(signature) else (signature,)
sig = sympify(sig)
cls._check_signature(sig)
if len(sig) == 1 and sig[0] == expr:
return S.IdentityFunction
return Expr.__new__(cls, sig, sympify(expr))
@classmethod
def _check_signature(cls, sig):
syms = set()
def rcheck(args):
for a in args:
if a.is_symbol:
if a in syms:
raise BadSignatureError("Duplicate symbol %s" % a)
syms.add(a)
elif isinstance(a, Tuple):
rcheck(a)
else:
raise BadSignatureError("Lambda signature should be only tuples"
" and symbols, not %s" % a)
if not isinstance(sig, Tuple):
raise BadSignatureError("Lambda signature should be a tuple not %s" % sig)
# Recurse through the signature:
rcheck(sig)
@property
def signature(self):
"""The expected form of the arguments to be unpacked into variables"""
return self._args[0]
@property
def expr(self):
"""The return value of the function"""
return self._args[1]
@property
def variables(self):
"""The variables used in the internal representation of the function"""
def _variables(args):
if isinstance(args, Tuple):
for arg in args:
yield from _variables(arg)
else:
yield args
return tuple(_variables(self.signature))
@property
def nargs(self):
from sympy.sets.sets import FiniteSet
return FiniteSet(len(self.signature))
bound_symbols = variables
@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 BadArgumentsError(temp % {
'name': self,
'args': list(self.nargs)[0],
'plural': 's'*(list(self.nargs)[0] != 1),
'given': n})
d = self._match_signature(self.signature, args)
return self.expr.xreplace(d)
def _match_signature(self, sig, args):
symargmap = {}
def rmatch(pars, args):
for par, arg in zip(pars, args):
if par.is_symbol:
symargmap[par] = arg
elif isinstance(par, Tuple):
if not isinstance(arg, (tuple, Tuple)) or len(args) != len(pars):
raise BadArgumentsError("Can't match %s and %s" % (args, pars))
rmatch(par, arg)
rmatch(sig, args)
return symargmap
@property
def is_identity(self):
"""Return ``True`` if this ``Lambda`` is an identity function. """
return self.signature == self.expr
def _eval_evalf(self, prec):
from sympy.core.evalf import prec_to_dps
return self.func(self.args[0], self.args[1].evalf(n=prec_to_dps(prec)))
class Subs(Expr):
"""
Represents unevaluated substitutions of an expression.
``Subs(expr, x, x0)`` represents the expression resulting
from substituting x with x0 in expr.
Parameters
==========
expr : Expr
An expression.
x : tuple, variable
A variable or list of distinct variables.
x0 : tuple or list of tuples
A point or list of evaluation points
corresponding to those variables.
Notes
=====
``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 prepended _)
# 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-prepended 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()
arg = e.args[0]
for vi, pi in undone:
if D not in e.xreplace({vi: D}).free_symbols:
if arg.has(vi):
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):
from sympy.utilities.exceptions import SymPyDeprecationWarning
SymPyDeprecationWarning(feature="expr_free_symbols method",
issue=21494,
deprecated_since_version="1.9").warn()
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().__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) == {new} and not any(
i.has(new) for i in self.args):
# the substitution is neutral
return self.xreplace({old: new})
# any occurrence 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:
f = self.expr
vp = V, P = self.variables, self.point
val = Add.fromiter(p.diff(s)*Subs(f.diff(v), *vp).doit()
for v, p in zip(V, P))
# these are all the free symbols in the expr
efree = f.free_symbols
# some symbols like IndexedBase include themselves and args
# as free symbols
compound = {i for i in efree if len(i.free_symbols) > 1}
# hide them and see what independent free symbols remain
dums = {Dummy() for i in compound}
masked = f.xreplace(dict(zip(compound, dums)))
ifree = masked.free_symbols - dums
# include the compound symbols
free = ifree | compound
# remove the variables already handled
free -= set(V)
# add back any free symbols of remaining compound symbols
free |= {i for j in free & compound for i in j.free_symbols}
# if symbols of s are in free then there is more to do
if free & s.free_symbols:
val += Subs(f.diff(s), self.variables, self.point).doit()
return val
def _eval_nseries(self, x, n, logx, cdir=0):
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, logx=None, cdir=0):
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.
Explanation
===========
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
idiff: computes the derivative implicitly
"""
if hasattr(f, 'diff'):
return f.diff(*symbols, **kwargs)
kwargs.setdefault('evaluate', True)
return _derivative_dispatch(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.
Explanation
===========
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, *, force=False, **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).
... '''
... 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, sympy.simplify.hyperexpand.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, factor=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)
"""
from sympy import Mul, log
if factor is False:
def _handle(x):
x1 = expand_mul(expand_log(x, deep=deep, force=force, factor=True))
if x1.count(log) <= x.count(log):
return x1
return x
expr = expr.replace(
lambda x: x.is_Mul and all(any(isinstance(i, log) and i.args[0].is_Rational
for i in Mul.make_args(j)) for j in x.as_numer_denom()),
lambda x: _handle(x))
return sympify(expr).expand(deep=deep, log=True, mul=False,
power_exp=False, power_base=False, multinomial=False,
basic=False, force=force, factor=factor)
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
========
sympy.core.expr.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.
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
See Also
========
expand
"""
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.
Parameters
==========
expr : Expr
If expr is an iterable, the sum of the op counts of the
items will be returned.
visual : bool, optional
If ``False`` (default) then the sum of the coefficients of the
visual expression will be returned.
If ``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.
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, Sum, 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')
EXP = Symbol('EXP')
while args:
a = args.pop()
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 == S.Exp1:
ops.append(EXP)
continue
if a.is_Pow and a.base == S.Exp1:
ops.append(EXP)
args.append(a.exp)
continue
if a.is_Mul or isinstance(a, LatticeOp):
o = Symbol(a.func.__name__.upper())
# count the args
ops.append(o*(len(a.args) - 1))
elif a.args and (
a.is_Pow or
a.is_Function or
isinstance(a, Derivative) or
isinstance(a, Integral) or
isinstance(a, Sum)):
# if it's not in the list above we don't
# consider a.func something to count, e.g.
# Tuple, MatrixSymbol, etc...
o = Symbol(a.func.__name__.upper())
ops.append(o)
if not a.is_Symbol:
args.extend(a.args)
elif isinstance(expr, 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()
if a.args:
o = Symbol(type(a).__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, dkeys=False):
"""Make all Rationals in expr Floats except those in exponents
(unless the exponents flag is set to True). When processing
dictionaries, don't modify the keys unless ``dkeys=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
Container types are not modified:
>>> type(nfloat((1, 2))) is tuple
True
"""
from sympy.core.power import Pow
from sympy.polys.rootoftools import RootOf
from sympy import MatrixBase
kw = dict(n=n, exponent=exponent, dkeys=dkeys)
if isinstance(expr, MatrixBase):
return expr.applyfunc(lambda e: nfloat(e, **kw))
# handling of iterable containers
if iterable(expr, exclude=str):
if isinstance(expr, (dict, Dict)):
if dkeys:
args = [tuple(map(lambda i: nfloat(i, **kw), a))
for a in expr.items()]
else:
args = [(k, nfloat(v, **kw)) for k, v in expr.items()]
if isinstance(expr, dict):
return type(expr)(args)
else:
return expr.func(*args)
elif isinstance(expr, Basic):
return expr.func(*[nfloat(a, **kw) for a in expr.args])
return type(expr)([nfloat(a, **kw) 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
elif rv.is_Atom:
return rv
elif rv.is_Relational:
args_nfloat = (nfloat(arg, **kw) for arg in rv.args)
return rv.func(*args_nfloat)
# 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
|
e8c945886ff7f2d9d72827ef900bfdd544c19b9efdbf2358db753217822807a1 | from collections import defaultdict
from functools import cmp_to_key, reduce
from operator import attrgetter
from .basic import Basic
from .compatibility import is_sequence
from .parameters import global_parameters
from .logic import _fuzzy_group, fuzzy_or, fuzzy_not
from .singleton import S
from .operations import AssocOp, AssocOpDispatcher
from .cache import cacheit
from .numbers import ilcm, igcd
from .expr import Expr
from .kind import UndefinedKind
# 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, evaluate=False), Add(y, x, evaluate=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):
"""
Expression representing addition operation for algebraic group.
Every argument of ``Add()`` must be ``Expr``. Infix operator ``+``
on most scalar objects in SymPy calls this class.
Another use of ``Add()`` is to represent the structure of abstract
addition so that its arguments can be substituted to return different
class. Refer to examples section for this.
``Add()`` evaluates the argument unless ``evaluate=False`` is passed.
The evaluation logic includes:
1. Flattening
``Add(x, Add(y, z))`` -> ``Add(x, y, z)``
2. Identity removing
``Add(x, 0, y)`` -> ``Add(x, y)``
3. Coefficient collecting by ``.as_coeff_Mul()``
``Add(x, 2*x)`` -> ``Mul(3, x)``
4. Term sorting
``Add(y, x, 2)`` -> ``Add(2, x, y)``
If no argument is passed, identity element 0 is returned. If single
element is passed, that element is returned.
Note that ``Add(*args)`` is more efficient than ``sum(args)`` because
it flattens the arguments. ``sum(a, b, c, ...)`` recursively adds the
arguments as ``a + (b + (c + ...))``, which has quadratic complexity.
On the other hand, ``Add(a, b, c, d)`` does not assume nested
structure, making the complexity linear.
Since addition is group operation, every argument should have the
same :obj:`sympy.core.kind.Kind()`.
Examples
========
>>> from sympy import Add, I
>>> from sympy.abc import x, y
>>> Add(x, 1)
x + 1
>>> Add(x, x)
2*x
>>> 2*x**2 + 3*x + I*y + 2*y + 2*x/5 + 1.0*y + 1
2*x**2 + 17*x/5 + 3.0*y + I*y + 1
If ``evaluate=False`` is passed, result is not evaluated.
>>> Add(1, 2, evaluate=False)
1 + 2
>>> Add(x, x, evaluate=False)
x + x
``Add()`` also represents the general structure of addition operation.
>>> from sympy import MatrixSymbol
>>> A,B = MatrixSymbol('A', 2,2), MatrixSymbol('B', 2,2)
>>> expr = Add(x,y).subs({x:A, y:B})
>>> expr
A + B
>>> type(expr)
<class 'sympy.matrices.expressions.matadd.MatAdd'>
Note that the printers don't display in args order.
>>> Add(x, 1)
x + 1
>>> Add(x, 1).args
(1, x)
See Also
========
MatAdd
"""
__slots__ = ()
is_Add = True
_args_type = Expr
@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 = []
extra = []
for o in seq:
# O(x)
if o.is_Order:
if o.expr.is_zero:
continue
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) and not extra:
# we know for sure the result will be nan
return [S.NaN], [], None
if coeff.is_Number or isinstance(coeff, AccumBounds):
coeff += o
if coeff is S.NaN and not extra:
# 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
extra.append(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 and not extra:
# 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 and not extra:
# 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_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_extended_nonnegative or f.is_real)]
elif coeff is S.NegativeInfinity:
newseq = [f for f in newseq if not (f.is_extended_nonpositive or f.is_real)]
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_extended_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)
if extra:
newseq += extra
noncommutative = True
# 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__
@property
def kind(self):
k = attrgetter('kind')
kinds = map(k, self.args)
kinds = frozenset(kinds)
if len(kinds) != 1:
# Since addition is group operator, kind must be same.
# We know that this is unexpected signature, so return this.
result = UndefinedKind
else:
result, = kinds
return result
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:
from sympy.utilities.iterables import sift
l1, l2 = sift(self.args, lambda x: x.has(*deps), binary=True)
return self._new_rawargs(*l2), tuple(l1)
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, deps=None):
"""
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))
elif e.is_Number and abs(e) != 1:
# handle the Float case: (2.0 + 4*x)**e -> 4**e*(0.5 + x)**e
c, m = zip(*[i.as_coeff_Mul() for i in self.args])
if any(i.is_Float for i in c): # XXX should this always be done?
big = -1
for i in c:
if abs(i) >= big:
big = abs(i)
if big > 0 and big != 1:
from sympy.functions.elementary.complexes import sign
bigs = (big, -big)
c = [sign(i) if i in bigs else i/big for i in c]
addpow = Add(*[c*m for c, m in zip(c, m)])**e
return big**e*addpow
@cacheit
def _eval_derivative(self, s):
return self.func(*[a.diff(s) for a in self.args])
def _eval_nseries(self, x, n, logx, cdir=0):
terms = [t.nseries(x, n=n, logx=logx, cdir=cdir) 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 self._matches_commutative(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.simplify.simplify import signsimp
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 = {v: k for k, v in reps.items()}
eq = signsimp(lhs.xreplace(reps) - rhs.xreplace(reps))
if eq.has(oo):
eq = eq.replace(
lambda x: x.is_Pow and x.base is oo,
lambda x: x.base)
return eq.xreplace(ireps)
else:
return signsimp(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):
"""
Decomposes an expression to its numerator part and its
denominator part.
Examples
========
>>> from sympy.abc import x, y, z
>>> (x*y/z).as_numer_denom()
(x*y, z)
>>> (x*(y + 1)/y**7).as_numer_denom()
(x*(y + 1), y**7)
See Also
========
sympy.core.expr.Expr.as_numer_denom
"""
# 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_meromorphic(self, x, a):
return _fuzzy_group((arg.is_meromorphic(x, a) for arg in self.args),
quick_exit=True)
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_extended_real = lambda self: _fuzzy_group(
(a.is_extended_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_infinite(self):
sawinf = False
for a in self.args:
ainf = a.is_infinite
if ainf is None:
return None
elif ainf is True:
# infinite+infinite might not be infinite
if sawinf is True:
return None
sawinf = True
return sawinf
def _eval_is_imaginary(self):
nz = []
im_I = []
for a in self.args:
if a.is_extended_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_extended_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 = 0
for a in self.args:
if a.is_extended_real:
if a.is_zero:
z += 1
elif a.is_zero is False:
nz.append(a)
else:
return
elif a.is_imaginary:
im += 1
elif (S.ImaginaryUnit*a).is_extended_real:
im_or_z = True
else:
return
if z == len(self.args):
return True
if len(nz) == 0 or len(nz) == len(self.args):
return None
b = self.func(*nz)
if b.is_zero:
if not im_or_z:
if im == 0:
return True
elif im == 1:
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_extended_positive(self):
from sympy.core.exprtools import _monotonic_sign
if self.is_number:
return super()._eval_is_extended_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_extended_positive and a.is_extended_nonnegative:
return True
if len(self.free_symbols) == 1:
v = _monotonic_sign(self)
if v is not None and v != self and v.is_extended_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_extended_positive
infinite = a.is_infinite
if infinite:
saw_INF.add(fuzzy_or((ispos, a.is_extended_nonnegative)))
if True in saw_INF and False in saw_INF:
return
if ispos:
pos = True
continue
elif a.is_extended_nonnegative:
nonneg = True
continue
elif a.is_extended_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_extended_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_extended_nonnegative:
v = _monotonic_sign(a)
if v is not None:
s = v + c
if s != self and s.is_extended_nonnegative:
return True
if len(self.free_symbols) == 1:
v = _monotonic_sign(self)
if v is not None and v != self and v.is_extended_nonnegative:
return True
def _eval_is_extended_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_extended_nonpositive:
v = _monotonic_sign(a)
if v is not None:
s = v + c
if s != self and s.is_extended_nonpositive:
return True
if len(self.free_symbols) == 1:
v = _monotonic_sign(self)
if v is not None and v != self and v.is_extended_nonpositive:
return True
def _eval_is_extended_negative(self):
from sympy.core.exprtools import _monotonic_sign
if self.is_number:
return super()._eval_is_extended_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_extended_negative and a.is_extended_nonpositive:
return True
if len(self.free_symbols) == 1:
v = _monotonic_sign(self)
if v is not None and v != self and v.is_extended_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_extended_negative
infinite = a.is_infinite
if infinite:
saw_INF.add(fuzzy_or((isneg, a.is_extended_nonpositive)))
if True in saw_INF and False in saw_INF:
return
if isneg:
neg = True
continue
elif a.is_extended_nonpositive:
nonpos = True
continue
elif a.is_extended_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, logx=None, cdir=0):
from sympy import expand_mul, Order, Piecewise, piecewise_fold, log
old = self
if old.has(Piecewise):
old = piecewise_fold(old)
# This expansion is the last part of expand_log. expand_log also calls
# expand_mul with factor=True, which would be more expensive
if any(isinstance(a, log) for a in self.args):
logflags = dict(deep=True, log=True, mul=False, power_exp=False,
power_base=False, multinomial=False, basic=False, force=False,
factor=False)
old = old.expand(**logflags)
expr = expand_mul(old)
if not expr.is_Add:
return expr.as_leading_term(x, logx=logx, cdir=cdir)
infinite = [t for t in expr.args if t.is_infinite]
leading_terms = [t.as_leading_term(x, logx=logx, cdir=cdir) for t in expr.args]
min, new_expr = Order(0), 0
try:
for term in leading_terms:
order = Order(term, x)
if not min or order not in min:
min = order
new_expr = term
elif min in order:
new_expr += term
except TypeError:
return expr
is_zero = new_expr.is_zero
if is_zero is None:
new_expr = new_expr.trigsimp().cancel()
is_zero = new_expr.is_zero
if is_zero is True:
# simple leading term analysis gave us cancelled terms but we have to send
# back a term, so compute the leading term (via series)
n0 = min.getn()
res = Order(1)
incr = S.One
while res.is_Order:
res = old._eval_nseries(x, n=n0+incr, logx=None, cdir=cdir).cancel().powsimp().trigsimp()
incr *= 2
return res.as_leading_term(x, logx=logx, cdir=cdir)
elif new_expr is S.NaN:
return old.func._from_args(infinite)
else:
return new_expr
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 _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_)
def __neg__(self):
if not global_parameters.distribute:
return super().__neg__()
return Add(*[-i for i in self.args])
add = AssocOpDispatcher('add')
from .mul import Mul, _keep_coeff, prod
from sympy.core.numbers import Rational
|
cea1191300b8386fb3deab2787eecf5d0f3eb6c828df994cf34601f890efd2cf | from typing import Tuple as tTuple
from collections.abc import Iterable
from functools import reduce
from .sympify import sympify, _sympify, SympifyError
from .basic import Basic, Atom
from .singleton import S
from .evalf import EvalfMixin, pure_complex
from .decorators import call_highest_priority, sympify_method_args, sympify_return
from .cache import cacheit
from .compatibility import as_int, default_sort_key
from sympy.utilities.misc import func_name
from mpmath.libmp import mpf_log, prec_to_dps
from collections import defaultdict
@sympify_method_args
class Expr(Basic, EvalfMixin):
"""
Base class for algebraic expressions.
Explanation
===========
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).
If you want to override the comparisons of expressions:
Should use _eval_is_ge for inequality, or _eval_is_eq, with multiple dispatch.
_eval_is_ge return true if x >= y, false if x < y, and None if the two types
are not comparable or the comparison is indeterminate
See Also
========
sympy.core.basic.Basic
"""
__slots__ = () # type: tTuple[str, ...]
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.
Explanation
===========
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:
if expr.base is S.Exp1:
# If we remove this, many doctests will go crazy:
# (keeps E**x sorted like the exp(x) function,
# part of exp(x) to E**x transition)
expr, exp = Function("exp")(expr.exp), S.One
else:
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
def __hash__(self) -> int:
# hash cannot be cached using cache_it because infinite recurrence
# occurs as hash is needed for setting cache dictionary keys
h = self._mhash
if h is None:
h = hash((type(self).__name__,) + self._hashable_content())
self._mhash = h
return h
def _hashable_content(self):
"""Return a tuple of information about self that can be used to
compute the hash. If a class defines additional attributes,
like ``name`` in Symbol, then this method should be updated
accordingly to return such relevant attributes.
Defining more than _hashable_content is necessary if __eq__ has
been defined by a class. See note about this in Basic.__eq__."""
return self._args
def __eq__(self, other):
try:
other = _sympify(other)
if not isinstance(other, Expr):
return False
except (SympifyError, SyntaxError):
return False
# check for pure number expr
if not (self.is_Number and other.is_Number) and (
type(self) != type(other)):
return False
a, b = self._hashable_content(), other._hashable_content()
if a != b:
return False
# check number *in* an expression
for a, b in zip(a, b):
if not isinstance(a, Expr):
continue
if a.is_Number and type(a) != type(b):
return False
return True
# ***************
# * 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
@property
def _add_handler(self):
return Add
@property
def _mul_handler(self):
return Mul
def __pos__(self):
return self
def __neg__(self):
# Mul has its own __neg__ routine, so we just
# create a 2-args Mul with the -1 in the canonical
# slot 0.
c = self.is_commutative
return Mul._from_args((S.NegativeOne, self), c)
def __abs__(self):
from sympy import Abs
return Abs(self)
@sympify_return([('other', 'Expr')], NotImplemented)
@call_highest_priority('__radd__')
def __add__(self, other):
return Add(self, other)
@sympify_return([('other', 'Expr')], NotImplemented)
@call_highest_priority('__add__')
def __radd__(self, other):
return Add(other, self)
@sympify_return([('other', 'Expr')], NotImplemented)
@call_highest_priority('__rsub__')
def __sub__(self, other):
return Add(self, -other)
@sympify_return([('other', 'Expr')], NotImplemented)
@call_highest_priority('__sub__')
def __rsub__(self, other):
return Add(other, -self)
@sympify_return([('other', 'Expr')], NotImplemented)
@call_highest_priority('__rmul__')
def __mul__(self, other):
return Mul(self, other)
@sympify_return([('other', 'Expr')], NotImplemented)
@call_highest_priority('__mul__')
def __rmul__(self, other):
return Mul(other, self)
@sympify_return([('other', 'Expr')], 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
@sympify_return([('other', 'Expr')], NotImplemented)
@call_highest_priority('__pow__')
def __rpow__(self, other):
return Pow(other, self)
@sympify_return([('other', 'Expr')], NotImplemented)
@call_highest_priority('__rtruediv__')
def __truediv__(self, other):
denom = Pow(other, S.NegativeOne)
if self is S.One:
return denom
else:
return Mul(self, denom)
@sympify_return([('other', 'Expr')], NotImplemented)
@call_highest_priority('__truediv__')
def __rtruediv__(self, other):
denom = Pow(self, S.NegativeOne)
if other is S.One:
return denom
else:
return Mul(other, denom)
@sympify_return([('other', 'Expr')], NotImplemented)
@call_highest_priority('__rmod__')
def __mod__(self, other):
return Mod(self, other)
@sympify_return([('other', 'Expr')], NotImplemented)
@call_highest_priority('__mod__')
def __rmod__(self, other):
return Mod(other, self)
@sympify_return([('other', 'Expr')], NotImplemented)
@call_highest_priority('__rfloordiv__')
def __floordiv__(self, other):
from sympy.functions.elementary.integers import floor
return floor(self / other)
@sympify_return([('other', 'Expr')], NotImplemented)
@call_highest_priority('__floordiv__')
def __rfloordiv__(self, other):
from sympy.functions.elementary.integers import floor
return floor(other / self)
@sympify_return([('other', 'Expr')], NotImplemented)
@call_highest_priority('__rdivmod__')
def __divmod__(self, other):
from sympy.functions.elementary.integers import floor
return floor(self / other), Mod(self, other)
@sympify_return([('other', 'Expr')], 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
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))
@sympify_return([('other', 'Expr')], NotImplemented)
def __ge__(self, other):
from .relational import GreaterThan
return GreaterThan(self, other)
@sympify_return([('other', 'Expr')], NotImplemented)
def __le__(self, other):
from .relational import LessThan
return LessThan(self, other)
@sympify_return([('other', 'Expr')], NotImplemented)
def __gt__(self, other):
from .relational import StrictGreaterThan
return StrictGreaterThan(self, other)
@sympify_return([('other', 'Expr')], NotImplemented)
def __lt__(self, other):
from .relational import StrictLessThan
return StrictLessThan(self, other)
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 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.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.
Explanation
===========
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.testing.randtest.random_complex_number
"""
free = self.free_symbols
prec = 1
if free:
from sympy.testing.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.
Explanation
===========
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, a few 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.
3) finding out zeros of denominator expression with free_symbols.
It won't be constant if there are zeros. It gives more negative
answers for expression that are not constant.
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
"""
def check_denominator_zeros(expression):
from sympy.solvers.solvers import denoms
retNone = False
for den in denoms(expression):
z = den.is_zero
if z is True:
return True
if z is None:
retNone = True
if retNone:
return None
return False
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
cd = check_denominator_zeros(self)
if cd is True:
return False
elif cd is None:
return None
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.
Explanation
===========
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.solvers import solve
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 not diff.is_number:
if constant is None:
# 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:
# this gives a number whether there are free symbols or not
ndiff = diff._random()
# is_comparable will work whether the result is real
# or complex; it could be None, however.
if ndiff and ndiff.is_comparable:
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.
#
# removed
# ns = nsimplify(diff)
# if diff.is_number and (not ns or ns == diff):
#
# The thought was that if it nsimplifies to 0 that's a sure sign
# to try the following to prove it; or if it changed but wasn't
# zero that might be a sign that it's not going to be easy to
# prove. But tests seem to be working without that logic.
#
if diff.is_number:
# 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.
sol = solve(diff, s, simplify=False)
if sol:
if s in sol:
# the self-consistent result is present
return True
if all(si.is_Integer for si in sol):
# perfect powers are removed at instantiation
# so surd s cannot be an integer
return False
if all(i.is_algebraic is False for i in sol):
# a surd is algebraic
return False
if any(si in surds for si in sol):
# it wasn't equal to s but it is in surds
# and different surds are not equal
return False
if any(nsimplify(s - si) == 0 and
simplify(s - si) == 0 for si 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 (is_comparable) 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):
finite = self.is_finite
if finite is False:
return False
extended_positive = self.is_extended_positive
if finite is True:
return extended_positive
if extended_positive is False:
return False
def _eval_is_negative(self):
finite = self.is_finite
if finite is False:
return False
extended_negative = self.is_extended_negative
if finite is True:
return extended_negative
if extended_negative is False:
return False
def _eval_is_extended_positive_negative(self, positive):
from sympy.core.numbers import pure_complex
from sympy.polys.numberfields import minimal_polynomial
from sympy.polys.polyerrors import NotAlgebraic
if self.is_number:
if self.is_extended_real is False:
return False
# check to see that we can get a value
try:
n2 = self._eval_evalf(2)
# XXX: This shouldn't be caught here
# Catches ValueError: hypsum() failed to converge to the requested
# 34 bits of accuracy
except ValueError:
return None
if n2 is None:
return None
if getattr(n2, '_prec', 1) == 1: # no significance
return None
if n2 is S.NaN:
return None
f = self.evalf(2)
if f.is_Float:
match = f, S.Zero
else:
match = pure_complex(f)
if match is None:
return False
r, i = match
if not (i.is_Number and r.is_Number):
return False
if r._prec != 1 and i._prec != 1:
return bool(not i and ((r > 0) if positive else (r < 0)))
elif r._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_extended_positive(self):
return self._eval_is_extended_positive_negative(positive=True)
def _eval_is_extended_negative(self):
return self._eval_is_extended_positive_negative(positive=False)
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.')
def _eval_endpoint(left):
c = a if left else b
if c is None:
return 0
else:
C = self.subs(x, c)
if C.has(S.NaN, S.Infinity, S.NegativeInfinity,
S.ComplexInfinity, AccumBounds):
if (a < b) != False:
C = limit(self, x, c, "+" if left else "-")
else:
C = limit(self, x, c, "-" if left else "+")
if isinstance(C, Limit):
raise NotImplementedError("Could not compute limit")
return C
if a == b:
return 0
A = _eval_endpoint(left=True)
if A is S.NaN:
return A
B = _eval_endpoint(left=False)
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_extended_real:
return self
elif self.is_imaginary:
return -self
def conjugate(self):
"""Returns the complex conjugate of 'self'."""
from sympy.functions.elementary.complexes import conjugate as c
return c(self)
def dir(self, x, cdir):
from sympy import log
minexp = S.Zero
if self.is_zero:
return S.Zero
arg = self
while arg:
minexp += S.One
arg = arg.diff(x)
coeff = arg.subs(x, 0)
if coeff is S.NaN:
coeff = arg.limit(x, 0)
if coeff is S.ComplexInfinity:
try:
coeff, _ = arg.leadterm(x)
if coeff.has(log(x)):
raise ValueError()
except ValueError:
coeff = arg.limit(x, 0)
if coeff != S.Zero:
break
return coeff*cdir**minexp
def _eval_transpose(self):
from sympy.functions.elementary.complexes import conjugate
if (self.is_complex or self.is_infinite):
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
startswith = getattr(order, "startswith", None)
if startswith is None:
reverse = False
else:
reverse = startswith('rev-')
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_poly(self, *gens, **args):
"""Converts ``self`` to a polynomial or returns ``None``.
Explanation
===========
>>> from sympy import sin
>>> from sympy.abc import x, y
>>> print((x**2 + x*y).as_poly())
Poly(x**2 + x*y, x, y, domain='ZZ')
>>> print((x**2 + x*y).as_poly(x, y))
Poly(x**2 + x*y, x, y, domain='ZZ')
>>> print((x**2 + sin(y)).as_poly(x, y))
None
"""
from sympy.polys import Poly, PolynomialError
try:
poly = Poly(self, *gens, **args)
if not poly.is_Poly:
return None
else:
return poly
except PolynomialError:
return None
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]
"""
from .numbers import Number, NumberSymbol
if order is None and self.is_Add:
# Spot the special case of Add(Number, Mul(Number, expr)) with the
# first number positive and thhe second number nagative
key = lambda x:not isinstance(x, (Number, NumberSymbol))
add_args = sorted(Add.make_args(self), key=key)
if (len(add_args) == 2
and isinstance(add_args[0], (Number, NumberSymbol))
and isinstance(add_args[1], Mul)):
mul_args = sorted(Mul.make_args(add_args[1]), key=key)
if (len(mul_args) == 2
and isinstance(mul_args[0], Number)
and add_args[0].is_positive
and mul_args[0].is_negative):
return add_args
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.
Explanation
===========
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.
Explanation
===========
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.
Examples
========
>>> 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_extended_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.
Explanation
===========
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.
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
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.Poly.coeff_monomial: efficiently find the single coefficient of a monomial in Poly
sympy.polys.polytools.Poly.nth: like coeff_monomial but powers of monomial terms are used
"""
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.
Examples
========
>> 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
one_c = self_c or x_c
xargs, nx = x.args_cnc(cset=True, warn=bool(not x_c))
# find the parts that pass the commutative terms
for a in args:
margs, nc = a.args_cnc(cset=True, warn=bool(not self_c))
if nc is None:
nc = []
if len(xargs) > len(margs):
continue
resid = margs.difference(xargs)
if len(resid) + len(xargs) == len(margs):
if one_c:
co.append(Mul(*(list(resid) + nc)))
else:
co.append((resid, nc))
if one_c:
if co == []:
return S.Zero
elif co:
return Add(*co)
else: # both 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.Poly.coeff_monomial: efficiently find the single coefficient of a monomial in Poly
sympy.polys.polytools.Poly.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), sympy.core.add.Add.as_two_terms(),
sympy.core.mul.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)
>>> ((x*(1 + y) + 0.4*x*(3 + 3*y))**2).as_content_primitive()
(1, 4.84*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):
""" expression -> a/b
See Also
========
as_numer_denom: return ``(a, b)`` instead of ``a/b``
"""
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
"""
from .add import _unevaluated_Add
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)
else:
return x
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)
if cs is not S.One:
args = [cs*t for t in newargs]
# args may be in different order
return _unevaluated_Add(*args)
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_zero:
return self
elif c == self:
return S.Zero
elif self == 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.utilities.exceptions import SymPyDeprecationWarning
>>> import warnings
>>> warnings.simplefilter("ignore", SymPyDeprecationWarning)
>>> 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}
"""
from sympy.utilities.exceptions import SymPyDeprecationWarning
SymPyDeprecationWarning(feature="expr_free_symbols method",
issue=21494,
deprecated_since_version="1.9").warn()
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.Zero
res = S.One
args = Mul.make_args(self)
exps = []
for arg in args:
if isinstance(arg, exp_polar):
exps += [arg.exp]
else:
res *= arg
piimult = S.Zero
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 piimult.is_number:
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.Half)*2
n += branchfact/2
c = coeff - branchfact
if allow_half:
nc = c.extract_additively(1)
if nc is not None:
n += S.Half
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.NegativeInfinity, 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_meromorphic(self, x, a):
# Default implementation, return True for constants.
return None if self.has(x) else True
def is_meromorphic(self, x, a):
"""
This tests whether an expression is meromorphic as
a function of the given symbol ``x`` at the point ``a``.
This method is intended as a quick test that will return
None if no decision can be made without simplification or
more detailed analysis.
Examples
========
>>> from sympy import zoo, log, sin, sqrt
>>> from sympy.abc import x
>>> f = 1/x**2 + 1 - 2*x**3
>>> f.is_meromorphic(x, 0)
True
>>> f.is_meromorphic(x, 1)
True
>>> f.is_meromorphic(x, zoo)
True
>>> g = x**log(3)
>>> g.is_meromorphic(x, 0)
False
>>> g.is_meromorphic(x, 1)
True
>>> g.is_meromorphic(x, zoo)
False
>>> h = sin(1/x)*x**2
>>> h.is_meromorphic(x, 0)
False
>>> h.is_meromorphic(x, 1)
True
>>> h.is_meromorphic(x, zoo)
True
Multivalued functions are considered meromorphic when their
branches are meromorphic. Thus most functions are meromorphic
everywhere except at essential singularities and branch points.
In particular, they will be meromorphic also on branch cuts
except at their endpoints.
>>> log(x).is_meromorphic(x, -1)
True
>>> log(x).is_meromorphic(x, 0)
False
>>> sqrt(x).is_meromorphic(x, -1)
True
>>> sqrt(x).is_meromorphic(x, 0)
False
"""
if not x.is_symbol:
raise TypeError("{} should be of symbol type".format(x))
a = sympify(a)
return self._eval_is_meromorphic(x, a)
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, cdir=0):
"""
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.
Parameters
==========
expr : Expression
The expression whose series is to be expanded.
x : Symbol
It is the variable of the expression to be calculated.
x0 : Value
The value around which ``x`` is calculated. Can be any value
from ``-oo`` to ``oo``.
n : Value
The number of terms upto which the series is to be expanded.
dir : String, optional
The series-expansion can be bi-directional. If ``dir="+"``,
then (x->x0+). If ``dir="-", then (x->x0-). For infinite
``x0`` (``oo`` or ``-oo``), the ``dir`` argument is determined
from the direction of the infinity (i.e., ``dir="-"`` for
``oo``).
logx : optional
It is used to replace any log(x) in the returned series with a
symbolic value rather than evaluating the actual value.
cdir : optional
It stands for complex direction, and indicates the direction
from which the expansion needs to be evaluated.
Examples
========
>>> from sympy import cos, exp, tan
>>> 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
>>> f = tan(x)
>>> f.series(x, 2, 6, "+")
tan(2) + (1 + tan(2)**2)*(x - 2) + (x - 2)**2*(tan(2)**3 + tan(2)) +
(x - 2)**3*(1/3 + 4*tan(2)**2/3 + tan(2)**4) + (x - 2)**4*(tan(2)**5 +
5*tan(2)**3/3 + 2*tan(2)/3) + (x - 2)**5*(2/15 + 17*tan(2)**2/15 +
2*tan(2)**4 + tan(2)**6) + O((x - 2)**6, (x, 2))
>>> f.series(x, 2, 3, "-")
tan(2) + (2 - x)*(-tan(2)**2 - 1) + (2 - x)**2*(tan(2)**3 + tan(2))
+ O((x - 2)**3, (x, 2))
Returns
=======
Expr : Expression
Series expansion of the expression about x0
Raises
======
TypeError
If "n" and "x0" are infinity objects
PoleError
If "x0" is an infinity object
"""
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='+', cdir=cdir)
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, cdir=cdir)
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, cdir=cdir)
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, cdir=cdir)
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, cdir=cdir)
newn = s1.getn()
if newn != ngot:
ndo = n + ceiling((n - ngot)*more/(newn - ngot))
s1 = self._eval_nseries(x, n=ndo, logx=logx, cdir=cdir)
while s1.getn() < n:
s1 = self._eval_nseries(x, n=ndo, logx=logx, cdir=cdir)
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()
elif s1.has(Order):
# asymptotic expansion
return s1
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, cdir=cdir))
def aseries(self, x=None, n=6, bound=0, hir=False):
"""Asymptotic Series expansion of self.
This is equivalent to ``self.series(x, oo, n)``.
Parameters
==========
self : Expression
The expression whose series is to be expanded.
x : Symbol
It is the variable of the expression to be calculated.
n : Value
The number of terms upto which the series is to be expanded.
hir : Boolean
Set this parameter to be True to produce hierarchical series.
It stops the recursion at an early level and may provide nicer
and more useful results.
bound : Value, Integer
Use the ``bound`` parameter to give limit on rewriting
coefficients in its normalised form.
Examples
========
>>> from sympy import sin, exp
>>> from sympy.abc import x
>>> e = sin(1/x + exp(-x)) - sin(1/x)
>>> e.aseries(x)
(1/(24*x**4) - 1/(2*x**2) + 1 + O(x**(-6), (x, oo)))*exp(-x)
>>> e.aseries(x, n=3, hir=True)
-exp(-2*x)*sin(1/x)/2 + exp(-x)*cos(1/x) + O(exp(-3*x), (x, oo))
>>> e = exp(exp(x)/(1 - 1/x))
>>> e.aseries(x)
exp(exp(x)/(1 - 1/x))
>>> e.aseries(x, bound=3) # doctest: +SKIP
exp(exp(x)/x**2)*exp(exp(x)/x)*exp(-exp(x) + exp(x)/(1 - 1/x) - exp(x)/x - exp(x)/x**2)*exp(exp(x))
Returns
=======
Expr
Asymptotic series expansion of the expression.
Notes
=====
This algorithm is directly induced from the limit computational algorithm provided by Gruntz.
It majorly uses the mrv and rewrite sub-routines. The overall idea of this algorithm is first
to look for the most rapidly varying subexpression w of a given expression f and then expands f
in a series in w. Then same thing is recursively done on the leading coefficient
till we get constant coefficients.
If the most rapidly varying subexpression of a given expression f is f itself,
the algorithm tries to find a normalised representation of the mrv set and rewrites f
using this normalised representation.
If the expansion contains an order term, it will be either ``O(x ** (-n))`` or ``O(w ** (-n))``
where ``w`` belongs to the most rapidly varying expression of ``self``.
References
==========
.. [1] A New Algorithm for Computing Asymptotic Series - Dominik Gruntz
.. [2] Gruntz thesis - p90
.. [3] http://en.wikipedia.org/wiki/Asymptotic_expansion
See Also
========
Expr.aseries: See the docstring of this function for complete details of this wrapper.
"""
from sympy import Order, Dummy, PoleError
from sympy.functions import exp, log
from sympy.series.gruntz import mrv, rewrite
if x.is_positive is x.is_negative is None:
xpos = Dummy('x', positive=True)
return self.subs(x, xpos).aseries(xpos, n, bound, hir).subs(xpos, x)
try:
om, exps = mrv(self, x)
except PoleError:
return self
# We move one level up by replacing `x` by `exp(x)`, and then
# computing the asymptotic series for f(exp(x)). Then asymptotic series
# can be obtained by moving one-step back, by replacing x by ln(x).
if x in om:
s = self.subs(x, exp(x)).aseries(x, n, bound, hir).subs(x, log(x))
if s.getO():
return s + Order(1/x**n, (x, S.Infinity))
return s
k = Dummy('k', positive=True)
# f is rewritten in terms of omega
func, logw = rewrite(exps, om, x, k)
if self in om:
if bound <= 0:
return self
s = (self.exp).aseries(x, n, bound=bound)
s = s.func(*[t.removeO() for t in s.args])
try:
res = exp(s.subs(x, 1/x).as_leading_term(x).subs(x, 1/x))
except PoleError:
res = self
func = exp(self.args[0] - res.args[0]) / k
logw = log(1/res)
s = func.series(k, 0, n)
# Hierarchical series
if hir:
return s.subs(k, exp(logw))
o = s.getO()
terms = sorted(Add.make_args(s.removeO()), key=lambda i: int(i.as_coeff_exponent(k)[1]))
s = S.Zero
has_ord = False
# Then we recursively expand these coefficients one by one into
# their asymptotic series in terms of their most rapidly varying subexpressions.
for t in terms:
coeff, expo = t.as_coeff_exponent(k)
if coeff.has(x):
# Recursive step
snew = coeff.aseries(x, n, bound=bound-1)
if has_ord and snew.getO():
break
elif snew.getO():
has_ord = True
s += (snew * k**expo)
else:
s += t
if not o or has_ord:
return s.subs(k, exp(logw))
return (s + o).subs(k, exp(logw))
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, cdir=0):
"""
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, cdir=cdir)
def _eval_lseries(self, x, logx=None, cdir=0):
# 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, cdir=cdir)
while series.is_Order:
n += 1
series = self._eval_nseries(x, n=n, logx=logx, cdir=cdir)
e = series.removeO()
yield e
if e is S.Zero:
return
while 1:
while 1:
n += 1
series = self._eval_nseries(x, n=n, logx=logx, cdir=cdir).removeO()
if e != series:
break
if (series - self).cancel() is S.Zero:
return
yield series - e
e = series
def nseries(self, x=None, x0=0, n=6, dir='+', logx=None, cdir=0):
"""
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, cdir=cdir)
else:
return self._eval_nseries(x, n=n, logx=logx, cdir=cdir)
def _eval_nseries(self, x, n, logx, cdir):
"""
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, Piecewise, piecewise_fold
from sympy.series.gruntz import calculate_series
if self.has(Piecewise):
expr = piecewise_fold(self)
else:
expr = self
if self.removeO() == 0:
return self
if logx is None:
d = Dummy('logx')
s = calculate_series(expr, x, d).subs(d, log(x))
else:
s = calculate_series(expr, x, logx)
return s.as_leading_term(x)
@cacheit
def as_leading_term(self, *symbols, logx=None, cdir=0):
"""
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, logx=logx, cdir=cdir)
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, logx=logx, cdir=cdir)
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, logx=None, cdir=0):
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, logx=None, cdir=0):
"""
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, logx=logx, cdir=cdir)
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 %s but got %s""" % (self, x, 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_dispatch(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 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 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, n=None):
"""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, Number
>>> 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
=====
The Python ``round`` function uses the SymPy ``round`` method so it
will always return a SymPy number (not a Python float or int):
>>> isinstance(round(S(123), -2), Number)
True
"""
from sympy.core.numbers import Float
x = self
if not x.is_number:
raise TypeError("can't round symbolic expression")
if not x.is_Atom:
if not pure_complex(x.n(2), or_real=True):
raise TypeError(
'Expected a number but got %s:' % func_name(x))
elif x in (S.NaN, S.Infinity, S.NegativeInfinity, S.ComplexInfinity):
return x
if x.is_extended_real is False:
r, i = x.as_real_imag()
return r.round(n) + S.ImaginaryUnit*i.round(n)
if not x:
return S.Zero if n is None else x
p = as_int(n or 0)
if x.is_Integer:
return Integer(round(int(x), p))
digits_to_decimal = _mag(x) # _mag(12) = 2, _mag(.012) = -1
allow = digits_to_decimal + p
precs = [f._prec for f in x.atoms(Float)]
dps = prec_to_dps(max(precs)) if precs else None
if dps is None:
# assume everything is exact so use the Python
# float default or whatever was requested
dps = max(15, allow)
else:
allow = min(allow, dps)
# this will shift all digits to right of decimal
# and give us dps to work with as an int
shift = -digits_to_decimal + dps
extra = 1 # how far we look past known digits
# NOTE
# mpmath will calculate the binary representation to
# an arbitrary number of digits but we must base our
# answer on a finite number of those digits, e.g.
# .575 2589569785738035/2**52 in binary.
# mpmath shows us that the first 18 digits are
# >>> Float(.575).n(18)
# 0.574999999999999956
# The default precision is 15 digits and if we ask
# for 15 we get
# >>> Float(.575).n(15)
# 0.575000000000000
# mpmath handles rounding at the 15th digit. But we
# need to be careful since the user might be asking
# for rounding at the last digit and our semantics
# are to round toward the even final digit when there
# is a tie. So the extra digit will be used to make
# that decision. In this case, the value is the same
# to 15 digits:
# >>> Float(.575).n(16)
# 0.5750000000000000
# Now converting this to the 15 known digits gives
# 575000000000000.0
# which rounds to integer
# 5750000000000000
# And now we can round to the desired digt, e.g. at
# the second from the left and we get
# 5800000000000000
# and rescaling that gives
# 0.58
# as the final result.
# If the value is made slightly less than 0.575 we might
# still obtain the same value:
# >>> Float(.575-1e-16).n(16)*10**15
# 574999999999999.8
# What 15 digits best represents the known digits (which are
# to the left of the decimal? 5750000000000000, the same as
# before. The only way we will round down (in this case) is
# if we declared that we had more than 15 digits of precision.
# For example, if we use 16 digits of precision, the integer
# we deal with is
# >>> Float(.575-1e-16).n(17)*10**16
# 5749999999999998.4
# and this now rounds to 5749999999999998 and (if we round to
# the 2nd digit from the left) we get 5700000000000000.
#
xf = x.n(dps + extra)*Pow(10, shift)
xi = Integer(xf)
# use the last digit to select the value of xi
# nearest to x before rounding at the desired digit
sign = 1 if x > 0 else -1
dif2 = sign*(xf - xi).n(extra)
if dif2 < 0:
raise NotImplementedError(
'not expecting int(x) to round away from 0')
if dif2 > .5:
xi += sign # round away from 0
elif dif2 == .5:
xi += sign if xi%2 else -sign # round toward even
# shift p to the new position
ip = p - shift
# let Python handle the int rounding then rescale
xr = round(xi.p, ip)
# restore scale
rv = Rational(xr, Pow(10, shift))
# return Float or Integer
if rv.is_Integer:
if n is None: # the single-arg case
return rv
# use str or else it won't be a float
return Float(str(rv), dps) # keep same precision
else:
if not allow and rv > self:
allow += 1
return Float(rv, allow)
__round__ = round
def _eval_derivative_matrix_lines(self, x):
from sympy.matrices.expressions.matexpr import _LeftRightArgs
return [_LeftRightArgs([S.One, S.One], higher=self._eval_derivative(x))]
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, MatrixExpr
from sympy.matrices.common import MatrixCommon
if isinstance(s, (MatrixCommon, Tuple, Iterable, MatrixExpr)):
return super()._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_meromorphic(self, x, a):
from sympy.calculus.util import AccumBounds
return (not self.is_Number or self.is_finite) and not isinstance(self, AccumBounds)
def _eval_is_algebraic_expr(self, syms):
return True
def _eval_nseries(self, x, n, logx, cdir=0):
return self
@property
def expr_free_symbols(self):
from sympy.utilities.exceptions import SymPyDeprecationWarning
SymPyDeprecationWarning(feature="expr_free_symbols method",
issue=21494,
deprecated_since_version="1.9").warn()
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 x
>>> 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 unchanged(func, *args):
"""Return True if `func` applied to the `args` is unchanged.
Can be used instead of `assert foo == foo`.
Examples
========
>>> from sympy import Piecewise, cos, pi
>>> from sympy.core.expr import unchanged
>>> from sympy.abc import x
>>> unchanged(cos, 1) # instead of assert cos(1) == cos(1)
True
>>> unchanged(cos, pi)
False
Comparison of args uses the builtin capabilities of the object's
arguments to test for equality so args can be defined loosely. Here,
the ExprCondPair arguments of Piecewise compare as equal to the
tuples that can be used to create the Piecewise:
>>> unchanged(Piecewise, (x, x > 1), (0, True))
True
"""
f = func(*args)
return f.func == func and f.args == args
class ExprBuilder:
def __init__(self, op, args=[], validator=None, check=True):
if not hasattr(op, "__call__"):
raise TypeError("op {} needs to be callable".format(op))
self.op = op
self.args = args
self.validator = validator
if (validator is not None) and check:
self.validate()
@staticmethod
def _build_args(args):
return [i.build() if isinstance(i, ExprBuilder) else i for i in args]
def validate(self):
if self.validator is None:
return
args = self._build_args(self.args)
self.validator(*args)
def build(self, check=True):
args = self._build_args(self.args)
if self.validator and check:
self.validator(*args)
return self.op(*args)
def append_argument(self, arg, check=True):
self.args.append(arg)
if self.validator and check:
self.validate(*self.args)
def __getitem__(self, item):
if item == 0:
return self.op
else:
return self.args[item-1]
def __repr__(self):
return str(self.build())
def search_element(self, elem):
for i, arg in enumerate(self.args):
if isinstance(arg, ExprBuilder):
ret = arg.search_index(elem)
if ret is not None:
return (i,) + ret
elif id(arg) == id(elem):
return (i,)
return None
from .mul import Mul
from .add import Add
from .power import Pow
from .function import Function, _derivative_dispatch
from .mod import Mod
from .exprtools import factor_terms
from .numbers import Integer, Rational
|
7332e8357ae1e1d03ff9aea8bc36b29173008bb85ddc8e2f9642aefeb016bd14 | from typing import Dict, Union, Type
from sympy.utilities.exceptions import SymPyDeprecationWarning
from .basic import S, Atom
from .compatibility import ordered
from .basic import Basic
from .evalf import EvalfMixin
from .function import AppliedUndef
from .sympify import _sympify, SympifyError
from .parameters import global_parameters
from sympy.core.logic import fuzzy_bool, fuzzy_xor, fuzzy_and, fuzzy_not
from sympy.logic.boolalg import Boolean, BooleanAtom
__all__ = (
'Rel', 'Eq', 'Ne', 'Lt', 'Le', 'Gt', 'Ge',
'Relational', 'Equality', 'Unequality', 'StrictLessThan', 'LessThan',
'StrictGreaterThan', 'GreaterThan',
)
from .expr import Expr
from sympy.multipledispatch import dispatch
from .containers import Tuple
from .symbol import Symbol
def _nontrivBool(side):
return isinstance(side, Boolean) and \
not isinstance(side, Atom)
# Note, see issue 4986. Ideally, we wouldn't want to subclass both Boolean
# and Expr.
# from .. import Expr
def _canonical(cond):
# return a condition in which all relationals are canonical
reps = {r: r.canonical for r in cond.atoms(Relational)}
return cond.xreplace(reps)
# XXX: AttributeError was being caught here but it wasn't triggered by any of
# the tests so I've removed it...
class Relational(Boolean, EvalfMixin):
"""Base class for all relation types.
Explanation
===========
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.ValidRelationOperator.
Examples
========
>>> from sympy import Rel
>>> from sympy.abc import x, y
>>> Rel(y, x + x**2, '==')
Eq(y, x**2 + x)
"""
__slots__ = ()
ValidRelationOperator = {} # type: Dict[Union[str, None], Type[Relational]]
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 Basic.
if cls is not Relational:
return Basic.__new__(cls, lhs, rhs, **assumptions)
# XXX: Why do this? There should be a separate function to make a
# particular subclass of Relational from a string.
#
# If called directly with an operator, look up the subclass
# corresponding to that operator and delegate to it
cls = cls.ValidRelationOperator.get(rop, None)
if cls is None:
raise ValueError("Invalid relational operator symbol: %r" % rop)
if not issubclass(cls, (Eq, Ne)):
# validate that Booleans are not being used in a relational
# other than Eq/Ne;
# Note: Symbol is a subclass of Boolean but is considered
# acceptable here.
if any(map(_nontrivBool, (lhs, rhs))):
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 cls(lhs, rhs, **assumptions)
@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 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 = {Eq: Eq, Gt: Lt, Ge: Le, Lt: Gt, Le: Ge, Ne: Ne}
a, b = self.args
return Relational.__new__(ops.get(self.func, self.func), b, a)
@property
def reversedsign(self):
"""Return the relationship with signs reversed.
Examples
========
>>> from sympy import Eq
>>> from sympy.abc import x
>>> Eq(x, 1)
Eq(x, 1)
>>> _.reversedsign
Eq(-x, -1)
>>> x < 1
x < 1
>>> _.reversedsign
-x > -1
"""
a, b = self.args
if not (isinstance(a, BooleanAtom) or isinstance(b, BooleanAtom)):
ops = {Eq: Eq, Gt: Lt, Ge: Le, Lt: Gt, Le: Ge, Ne: Ne}
return Relational.__new__(ops.get(self.func, self.func), -a, -b)
else:
return self
@property
def negated(self):
"""Return the negated relationship.
Examples
========
>>> from sympy import Eq
>>> from sympy.abc import x
>>> Eq(x, 1)
Eq(x, 1)
>>> _.negated
Ne(x, 1)
>>> x < 1
x < 1
>>> _.negated
x >= 1
Notes
=====
This works more or less identical to ``~``/``Not``. The difference is
that ``negated`` returns the relationship even if ``evaluate=False``.
Hence, this is useful in code when checking for e.g. negated relations
to existing ones as it will not be affected by the `evaluate` flag.
"""
ops = {Eq: Ne, Ge: Lt, Gt: Le, Le: Gt, Lt: Ge, Ne: Eq}
# If there ever will be new Relational subclasses, the following line
# will work until it is properly sorted out
# return ops.get(self.func, lambda a, b, evaluate=False: ~(self.func(a,
# b, evaluate=evaluate)))(*self.args, evaluate=False)
return Relational.__new__(ops.get(self.func), *self.args)
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, canonically removing a sign or else
ordering the args canonically. 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
>>> (-y < -x).canonical
x < y
"""
args = self.args
r = self
if r.rhs.is_number:
if r.rhs.is_Number and 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
LHS_CEMS = getattr(r.lhs, 'could_extract_minus_sign', None)
RHS_CEMS = getattr(r.rhs, 'could_extract_minus_sign', None)
if isinstance(r.lhs, BooleanAtom) or isinstance(r.rhs, BooleanAtom):
return r
# Check if first value has negative sign
if LHS_CEMS and LHS_CEMS():
return r.reversedsign
elif not r.rhs.is_number and RHS_CEMS and RHS_CEMS():
# Right hand side has a minus, but not lhs.
# How does the expression with reversed signs behave?
# This is so that expressions of the type
# Eq(x, -y) and Eq(-x, y)
# have the same canonical representation
expr1, _ = ordered([r.lhs, -r.rhs])
if expr1 != r.lhs:
return r.reversed.reversedsign
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
left, right = [i.equals(j,
failing_expression=failing_expression)
for i, j in zip(a.args, b.args)]
if left is True:
return right
if right is True:
return left
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 = (left, right, 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
left = a.lhs.equals(b.lhs,
failing_expression=failing_expression)
if left is False:
return False
right = a.rhs.equals(b.rhs,
failing_expression=failing_expression)
if right is False:
return False
if left is True:
return right
return left
def _eval_simplify(self, **kwargs):
from .add import Add
from sympy.core.expr import Expr
r = self
r = r.func(*[i.simplify(**kwargs) for i in r.args])
if r.is_Relational:
if not isinstance(r.lhs, Expr) or not isinstance(r.rhs, Expr):
return r
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 there is only one symbol in the expression,
# try to write it on a simplified form
free = list(filter(lambda x: x.is_real is not False, r.free_symbols))
if len(free) == 1:
try:
from sympy.solvers.solveset import linear_coeffs
x = free.pop()
dif = r.lhs - r.rhs
m, b = linear_coeffs(dif, x)
if m.is_zero is False:
if m.is_negative:
# Dividing with a negative number, so change order of arguments
# canonical will put the symbol back on the lhs later
r = r.func(-b / m, x)
else:
r = r.func(x, -b / m)
else:
r = r.func(b, S.zero)
except ValueError:
# maybe not a linear function, try polynomial
from sympy.polys import Poly, poly, PolynomialError, gcd
try:
p = poly(dif, x)
c = p.all_coeffs()
constant = c[-1]
c[-1] = 0
scale = gcd(c)
c = [ctmp / scale for ctmp in c]
r = r.func(Poly.from_list(c, x).as_expr(), -constant / scale)
except PolynomialError:
pass
elif len(free) >= 2:
try:
from sympy.solvers.solveset import linear_coeffs
from sympy.polys import gcd
free = list(ordered(free))
dif = r.lhs - r.rhs
m = linear_coeffs(dif, *free)
constant = m[-1]
del m[-1]
scale = gcd(m)
m = [mtmp / scale for mtmp in m]
nzm = list(filter(lambda f: f[0] != 0, list(zip(m, free))))
if scale.is_zero is False:
if constant != 0:
# lhs: expression, rhs: constant
newexpr = Add(*[i * j for i, j in nzm])
r = r.func(newexpr, -constant / scale)
else:
# keep first term on lhs
lhsterm = nzm[0][0] * nzm[0][1]
del nzm[0]
newexpr = Add(*[i * j for i, j in nzm])
r = r.func(lhsterm, -newexpr)
else:
r = r.func(constant, S.zero)
except ValueError:
pass
# Did we get a simplified result?
r = r.canonical
measure = kwargs['measure']
if measure(r) < kwargs['ratio'] * measure(self):
return r
else:
return self
def _eval_trigsimp(self, **opts):
from sympy.simplify import trigsimp
return self.func(trigsimp(self.lhs, **opts), trigsimp(self.rhs, **opts))
def expand(self, **kwargs):
args = (arg.expand(**kwargs) for arg in self.args)
return self.func(*args)
def __bool__(self):
raise TypeError("cannot determine truth value of Relational")
def _eval_as_set(self):
# self is univariate and periodicity(self, x) in (0, None)
from sympy.solvers.inequalities import solve_univariate_inequality
from sympy.sets.conditionset import ConditionSet
syms = self.free_symbols
assert len(syms) == 1
x = syms.pop()
try:
xset = solve_univariate_inequality(self, x, relational=False)
except NotImplementedError:
# solve_univariate_inequality raises NotImplementedError for
# unsolvable equations/inequalities.
xset = ConditionSet(x, self, S.Reals)
return xset
@property
def binary_symbols(self):
# override where necessary
return set()
Rel = Relational
class Equality(Relational):
"""An equal relation between two objects.
Explanation
===========
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
=====
Python treats 1 and True (and 0 and False) as being equal; SymPy
does not. And integer will always compare as unequal to a Boolean:
>>> Eq(True, 1), True == 1
(False, True)
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=None, **options):
if rhs is None:
SymPyDeprecationWarning(
feature="Eq(expr) with rhs default to 0",
useinstead="Eq(expr, 0)",
issue=16587,
deprecated_since_version="1.5"
).warn()
rhs = 0
evaluate = options.pop('evaluate', global_parameters.evaluate)
lhs = _sympify(lhs)
rhs = _sympify(rhs)
if evaluate:
val = is_eq(lhs, rhs)
if val is None:
return cls(lhs, rhs, evaluate=False)
else:
return _sympify(val)
return Relational.__new__(cls, lhs, rhs)
@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)
"""
from .add import _unevaluated_Add, Add
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 {self.lhs}
elif self.rhs.is_Symbol:
return {self.rhs}
return set()
def _eval_simplify(self, **kwargs):
from .add import Add
from sympy.core.expr import Expr
from sympy.solvers.solveset import linear_coeffs
# standard simplify
e = super()._eval_simplify(**kwargs)
if not isinstance(e, Equality):
return e
if not isinstance(e.lhs, Expr) or not isinstance(e.rhs, Expr):
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)
measure = kwargs['measure']
if measure(enew) <= kwargs['ratio'] * measure(e):
e = enew
except ValueError:
pass
return e.canonical
def integrate(self, *args, **kwargs):
"""See the integrate function in sympy.integrals"""
from sympy.integrals import integrate
return integrate(self, *args, **kwargs)
def as_poly(self, *gens, **kwargs):
'''Returns lhs-rhs as a Poly
Examples
========
>>> from sympy import Eq
>>> from sympy.abc import x
>>> Eq(x**2, 1).as_poly(x)
Poly(x**2 - 1, x, domain='ZZ')
'''
return (self.lhs - self.rhs).as_poly(*gens, **kwargs)
Eq = Equality
class Unequality(Relational):
"""An unequal relation between two objects.
Explanation
===========
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_parameters.evaluate)
if evaluate:
val = is_neq(lhs, rhs)
if val is None:
return cls(lhs, rhs, evaluate=False)
else:
return _sympify(val)
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 {self.lhs}
elif self.rhs.is_Symbol:
return {self.rhs}
return set()
def _eval_simplify(self, **kwargs):
# simplify as an equality
eq = Equality(*self.args)._eval_simplify(**kwargs)
if isinstance(eq, Equality):
# send back Ne with the new args
return self.func(*eq.args)
return eq.negated # result of Ne is the negated 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):
try:
lhs = _sympify(lhs)
rhs = _sympify(rhs)
except SympifyError:
return NotImplemented
evaluate = options.pop('evaluate', global_parameters.evaluate)
if evaluate:
for me in (lhs, rhs):
if me.is_extended_real is False:
raise TypeError("Invalid comparison of non-real %s" % me)
if me is S.NaN:
raise TypeError("Invalid NaN comparison")
# 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.
return cls._eval_relation(lhs, rhs, **options)
# make a "non-evaluated" Expr for the inequality
return Relational.__new__(cls, lhs, rhs, **options)
@classmethod
def _eval_relation(cls, lhs, rhs, **options):
val = cls._eval_fuzzy_relation(lhs, rhs)
if val is None:
return cls(lhs, rhs, evaluate=False)
else:
return _sympify(val)
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.
Explanation
===========
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/reference/expressions.html#not-in). 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.__bool__()) 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 __bool__ 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_fuzzy_relation(cls, lhs, rhs):
return is_ge(lhs, rhs)
Ge = GreaterThan
class LessThan(_Less):
__doc__ = GreaterThan.__doc__
__slots__ = ()
rel_op = '<='
@classmethod
def _eval_fuzzy_relation(cls, lhs, rhs):
return is_le(lhs, rhs)
Le = LessThan
class StrictGreaterThan(_Greater):
__doc__ = GreaterThan.__doc__
__slots__ = ()
rel_op = '>'
@classmethod
def _eval_fuzzy_relation(cls, lhs, rhs):
return is_gt(lhs, rhs)
Gt = StrictGreaterThan
class StrictLessThan(_Less):
__doc__ = GreaterThan.__doc__
__slots__ = ()
rel_op = '<'
@classmethod
def _eval_fuzzy_relation(cls, lhs, rhs):
return is_lt(lhs, 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,
}
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
@dispatch(Expr, Expr)
def _eval_is_ge(lhs, rhs):
return None
@dispatch(Basic, Basic)
def _eval_is_eq(lhs, rhs):
return None
@dispatch(Tuple, Expr) # type: ignore
def _eval_is_eq(lhs, rhs): # noqa:F811
return False
@dispatch(Tuple, AppliedUndef) # type: ignore
def _eval_is_eq(lhs, rhs): # noqa:F811
return None
@dispatch(Tuple, Symbol) # type: ignore
def _eval_is_eq(lhs, rhs): # noqa:F811
return None
@dispatch(Tuple, Tuple) # type: ignore
def _eval_is_eq(lhs, rhs): # noqa:F811
if len(lhs) != len(rhs):
return False
return fuzzy_and(fuzzy_bool(is_eq(s, o)) for s, o in zip(lhs, rhs))
def is_lt(lhs, rhs, assumptions=None):
"""Fuzzy bool for lhs is strictly less than rhs.
See the docstring for :func:`~.is_ge` for more.
"""
return fuzzy_not(is_ge(lhs, rhs, assumptions))
def is_gt(lhs, rhs, assumptions=None):
"""Fuzzy bool for lhs is strictly greater than rhs.
See the docstring for :func:`~.is_ge` for more.
"""
return fuzzy_not(is_le(lhs, rhs, assumptions))
def is_le(lhs, rhs, assumptions=None):
"""Fuzzy bool for lhs is less than or equal to rhs.
See the docstring for :func:`~.is_ge` for more.
"""
return is_ge(rhs, lhs, assumptions)
def is_ge(lhs, rhs, assumptions=None):
"""
Fuzzy bool for *lhs* is greater than or equal to *rhs*.
Parameters
==========
lhs : Expr
The left-hand side of the expression, must be sympified,
and an instance of expression. Throws an exception if
lhs is not an instance of expression.
rhs : Expr
The right-hand side of the expression, must be sympified
and an instance of expression. Throws an exception if
lhs is not an instance of expression.
assumptions: Boolean, optional
Assumptions taken to evaluate the inequality.
Returns
=======
``True`` if *lhs* is greater than or equal to *rhs*, ``False`` if *lhs*
is less than *rhs*, and ``None`` if the comparison between *lhs* and
*rhs* is indeterminate.
Explanation
===========
This function is intended to give a relatively fast determination and
deliberately does not attempt slow calculations that might help in
obtaining a determination of True or False in more difficult cases.
The four comparison functions ``is_le``, ``is_lt``, ``is_ge``, and ``is_gt`` are
each implemented in terms of ``is_ge`` in the following way:
is_ge(x, y) := is_ge(x, y)
is_le(x, y) := is_ge(y, x)
is_lt(x, y) := fuzzy_not(is_ge(x, y))
is_gt(x, y) := fuzzy_not(is_ge(y, x))
Therefore, supporting new type with this function will ensure behavior for
other three functions as well.
To maintain these equivalences in fuzzy logic it is important that in cases where
either x or y is non-real all comparisons will give None.
Examples
========
>>> from sympy import S, Q
>>> from sympy.core.relational import is_ge, is_le, is_gt, is_lt
>>> from sympy.abc import x
>>> is_ge(S(2), S(0))
True
>>> is_ge(S(0), S(2))
False
>>> is_le(S(0), S(2))
True
>>> is_gt(S(0), S(2))
False
>>> is_lt(S(2), S(0))
False
Assumptions can be passed to evaluate the quality which is otherwise
indeterminate.
>>> print(is_ge(x, S(0)))
None
>>> is_ge(x, S(0), assumptions=Q.positive(x))
True
New types can be supported by dispatching to ``_eval_is_ge``.
>>> from sympy import Expr, sympify
>>> from sympy.multipledispatch import dispatch
>>> class MyExpr(Expr):
... def __new__(cls, arg):
... return super().__new__(cls, sympify(arg))
... @property
... def value(self):
... return self.args[0]
>>> @dispatch(MyExpr, MyExpr)
... def _eval_is_ge(a, b):
... return is_ge(a.value, b.value)
>>> a = MyExpr(1)
>>> b = MyExpr(2)
>>> is_ge(b, a)
True
>>> is_le(a, b)
True
"""
from sympy.assumptions.wrapper import AssumptionsWrapper, is_extended_nonnegative
if not (isinstance(lhs, Expr) and isinstance(rhs, Expr)):
raise TypeError("Can only compare inequalities with Expr")
retval = _eval_is_ge(lhs, rhs)
if retval is not None:
return retval
else:
n2 = _n2(lhs, rhs)
if n2 is not None:
# use float comparison for infinity.
# otherwise get stuck in infinite recursion
if n2 in (S.Infinity, S.NegativeInfinity):
n2 = float(n2)
return n2 >= 0
_lhs = AssumptionsWrapper(lhs, assumptions)
_rhs = AssumptionsWrapper(rhs, assumptions)
if _lhs.is_extended_real and _rhs.is_extended_real:
if (_lhs.is_infinite and _lhs.is_extended_positive) or (_rhs.is_infinite and _rhs.is_extended_negative):
return True
diff = lhs - rhs
if diff is not S.NaN:
rv = is_extended_nonnegative(diff, assumptions)
if rv is not None:
return rv
def is_neq(lhs, rhs, assumptions=None):
"""Fuzzy bool for lhs does not equal rhs.
See the docstring for :func:`~.is_eq` for more.
"""
return fuzzy_not(is_eq(lhs, rhs, assumptions))
def is_eq(lhs, rhs, assumptions=None):
"""
Fuzzy bool representing mathematical equality between *lhs* and *rhs*.
Parameters
==========
lhs : Expr
The left-hand side of the expression, must be sympified.
rhs : Expr
The right-hand side of the expression, must be sympified.
assumptions: Boolean, optional
Assumptions taken to evaluate the equality.
Returns
=======
``True`` if *lhs* is equal to *rhs*, ``False`` is *lhs* is not equal to *rhs*,
and ``None`` if the comparison between *lhs* and *rhs* is indeterminate.
Explanation
===========
This function is intended to give a relatively fast determination and
deliberately does not attempt slow calculations that might help in
obtaining a determination of True or False in more difficult cases.
:func:`~.is_neq` calls this function to return its value, so supporting
new type with this function will ensure correct behavior for ``is_neq``
as well.
Examples
========
>>> from sympy import Q, S
>>> from sympy.core.relational import is_eq, is_neq
>>> from sympy.abc import x
>>> is_eq(S(0), S(0))
True
>>> is_neq(S(0), S(0))
False
>>> is_eq(S(0), S(2))
False
>>> is_neq(S(0), S(2))
True
Assumptions can be passed to evaluate the equality which is otherwise
indeterminate.
>>> print(is_eq(x, S(0)))
None
>>> is_eq(x, S(0), assumptions=Q.zero(x))
True
New types can be supported by dispatching to ``_eval_is_eq``.
>>> from sympy import Basic, sympify
>>> from sympy.multipledispatch import dispatch
>>> class MyBasic(Basic):
... def __new__(cls, arg):
... return Basic.__new__(cls, sympify(arg))
... @property
... def value(self):
... return self.args[0]
...
>>> @dispatch(MyBasic, MyBasic)
... def _eval_is_eq(a, b):
... return is_eq(a.value, b.value)
...
>>> a = MyBasic(1)
>>> b = MyBasic(1)
>>> is_eq(a, b)
True
>>> is_neq(a, b)
False
"""
from sympy.assumptions.wrapper import (AssumptionsWrapper,
is_infinite, is_extended_real)
from sympy.core.add import Add
from sympy.functions.elementary.complexes import arg
from sympy.simplify.simplify import clear_coefficients
from sympy.utilities.iterables import sift
# here, _eval_Eq is only called for backwards compatibility
# new code should use is_eq with multiple dispatch as
# outlined in the docstring
for side1, side2 in (lhs, rhs), (rhs, lhs):
eval_func = getattr(side1, '_eval_Eq', None)
if eval_func is not None:
retval = eval_func(side2)
if retval is not None:
return retval
retval = _eval_is_eq(lhs, rhs)
if retval is not None:
return retval
if dispatch(type(lhs), type(rhs)) != dispatch(type(rhs), type(lhs)):
retval = _eval_is_eq(rhs, lhs)
if retval is not None:
return retval
# retval is still None, so go through the equality logic
# If expressions have the same structure, they must be equal.
if lhs == rhs:
return True # e.g. True == True
elif all(isinstance(i, BooleanAtom) for i in (rhs, lhs)):
return False # True != False
elif not (lhs.is_Symbol or rhs.is_Symbol) and (
isinstance(lhs, Boolean) !=
isinstance(rhs, Boolean)):
return False # only Booleans can equal Booleans
_lhs = AssumptionsWrapper(lhs, assumptions)
_rhs = AssumptionsWrapper(rhs, assumptions)
if _lhs.is_infinite or _rhs.is_infinite:
if fuzzy_xor([_lhs.is_infinite, _rhs.is_infinite]):
return False
if fuzzy_xor([_lhs.is_extended_real, _rhs.is_extended_real]):
return False
if fuzzy_and([_lhs.is_extended_real, _rhs.is_extended_real]):
return fuzzy_xor([_lhs.is_extended_positive, fuzzy_not(_rhs.is_extended_positive)])
# Try to split real/imaginary parts and equate them
I = S.ImaginaryUnit
def split_real_imag(expr):
real_imag = lambda t: (
'real' if is_extended_real(t, assumptions) else
'imag' if is_extended_real(I*t, assumptions) else None)
return sift(Add.make_args(expr), real_imag)
lhs_ri = split_real_imag(lhs)
if not lhs_ri[None]:
rhs_ri = split_real_imag(rhs)
if not rhs_ri[None]:
eq_real = is_eq(Add(*lhs_ri['real']), Add(*rhs_ri['real']), assumptions)
eq_imag = is_eq(I * Add(*lhs_ri['imag']), I * Add(*rhs_ri['imag']), assumptions)
return fuzzy_and(map(fuzzy_bool, [eq_real, eq_imag]))
# Compare e.g. zoo with 1+I*oo by comparing args
arglhs = arg(lhs)
argrhs = arg(rhs)
# Guard against Eq(nan, nan) -> False
if not (arglhs == S.NaN and argrhs == S.NaN):
return fuzzy_bool(is_eq(arglhs, argrhs, assumptions))
if all(isinstance(i, Expr) for i in (lhs, rhs)):
# see if the difference evaluates
dif = lhs - rhs
_dif = AssumptionsWrapper(dif, assumptions)
z = _dif.is_zero
if z is not None:
if z is False and _dif.is_commutative: # issue 10728
return False
if z:
return True
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
_n = AssumptionsWrapper(n, assumptions)
_d = AssumptionsWrapper(d, assumptions)
if _n.is_zero:
rv = _d.is_nonzero
elif _n.is_finite:
if _d.is_infinite:
rv = 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(is_eq(*args, assumptions))
if rv is True:
rv = None
elif any(is_infinite(a, assumptions) for a in Add.make_args(n)):
# (inf or nan)/x != 0
rv = False
if rv is not None:
return rv
|
7c7ce8a9f0619f226f1a78154a1e5f375fa9b1fc91648fbfcd9ae4a0bedefae3 | import numbers
import decimal
import fractions
import math
import re as regex
import sys
from .containers import Tuple
from .sympify import (SympifyError, converter, sympify, _convert_numpy_types, _sympify,
_is_numpy_instance)
from .singleton import S, Singleton
from .expr import Expr, AtomicExpr
from .evalf import pure_complex
from .decorators import _sympifyit
from .cache import cacheit, clear_cache
from .logic import fuzzy_not
from sympy.core.compatibility import (as_int, HAS_GMPY, SYMPY_INTS,
gmpy)
from sympy.core.cache import lru_cache
from .kind import NumberKind
from sympy.multipledispatch import dispatch
import mpmath
import mpmath.libmp as mlib
from mpmath.libmp import bitcount
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, _normalize as mpf_normalize,
prec_to_dps)
from sympy.utilities.misc import debug, filldedent
from .parameters import global_parameters
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.
Examples
========
If ``tol`` is None then True will be returned if
``abs(z1 - z2)*10**p <= 5`` where ``p`` is minimum value of the
decimal precision of each value.
>>> from sympy.core.numbers import comp, pi
>>> pi4 = pi.n(4); pi4
3.142
>>> comp(_, 3.142)
True
>>> comp(pi4, 3.141)
False
>>> comp(pi4, 3.143)
False
A comparison of strings will be made
if ``z1`` is a Number and ``z2`` is a string or ``tol`` is ''.
>>> comp(pi4, 3.1415)
True
>>> comp(pi4, 3.1415, '')
False
When ``tol`` is provided and ``z2`` is non-zero and
``|z1| > 1`` the error is normalized by ``|z1|``:
>>> abs(pi4 - 3.14)/pi4
0.000509791731426756
>>> comp(pi4, 3.14, .001) # difference less than 0.1%
True
>>> comp(pi4, 3.14, .0005) # difference less than 0.1%
False
When ``|z1| <= 1`` the absolute error is used:
>>> 1/pi4
0.3183
>>> abs(1/pi4 - 0.3183)/(1/pi4)
3.07371499106316e-5
>>> abs(1/pi4 - 0.3183)
9.78393554684764e-6
>>> comp(1/pi4, 0.3183, 1e-5)
True
To see if the absolute error between ``z1`` and ``z2`` is less
than or equal to ``tol``, call this as ``comp(z1 - z2, 0, tol)``
or ``comp(z1 - z2, tol=tol)``:
>>> abs(pi4 - 3.14)
0.00160156249999988
>>> comp(pi4 - 3.14, 0, .002)
True
>>> comp(pi4 - 3.14, 0, .001)
False
"""
if type(z2) is str:
if not pure_complex(z1, or_real=True):
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:
a, b = z1, z2
if tol == '':
return str(a) == str(b)
if tol is None:
a, b = sympify(a), sympify(b)
if not all(i.is_number for i in (a, b)):
raise ValueError('expecting 2 numbers')
fa = a.atoms(Float)
fb = b.atoms(Float)
if not fa and not fb:
# no floats -- compare exactly
return a == b
# get a to be pure_complex
for do in range(2):
ca = pure_complex(a, or_real=True)
if not ca:
if fa:
a = a.n(prec_to_dps(min([i._prec for i in fa])))
ca = pure_complex(a, or_real=True)
break
else:
fa, fb = fb, fa
a, b = b, a
cb = pure_complex(b)
if not cb and fb:
b = b.n(prec_to_dps(min([i._prec for i in fb])))
cb = pure_complex(b, or_real=True)
if ca and cb and (ca[1] or cb[1]):
return all(comp(i, j) for i, j in zip(ca, cb))
tol = 10**prec_to_dps(min(a._prec, getattr(b, '_prec', a._prec)))
return int(abs(a - b)*tol) <= 5
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 fzero
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
_floatpat = regex.compile(r"[-+]?((\d*\.\d+)|(\d+\.?))")
def _literal_float(f):
"""Return True if n starts like a floating point number."""
return bool(_floatpat.match(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.
Explanation
===========
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()
if HAS_GMPY: # Using gmpy if present to speed up.
for b in args_temp:
a = gmpy.gcd(a, b) if b else a
return as_int(a)
for b in args_temp:
a = math.gcd(a, b)
return a
igcd2 = math.gcd
def igcd_lehmer(a, b):
"""Computes greatest common divisor of two integers.
Explanation
===========
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*sys.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).
Examples
========
>>> 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 returned 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
==========
.. [1] https://en.wikipedia.org/wiki/Modular_multiplicative_inverse
.. [2] 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.
Explanation
===========
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
kind = NumberKind
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, str):
_obj = obj.lower() # float('INF') == float('inf')
if _obj == 'nan':
return S.NaN
elif _obj == 'inf':
return S.Infinity
elif _obj == '+inf':
return S.Infinity
elif _obj == '-inf':
return S.NegativeInfinity
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
from sympy.functions.elementary.complexes import sign
try:
other = Number(other)
if self.is_infinite or S.NaN in (self, other):
return (S.NaN, S.NaN)
except TypeError:
return NotImplemented
if not other:
raise ZeroDivisionError('modulo by zero')
if self.is_Integer and other.is_Integer:
return Tuple(*divmod(self.p, other.p))
elif isinstance(other, Float):
rat = self/Rational(other)
else:
rat = self/other
if other.is_finite:
w = int(rat) if rat >= 0 else int(rat) - 1
r = self - other*w
else:
w = 0 if not self or (sign(self) == sign(other)) else -1
r = other if w else self
return Tuple(w, r)
def __rdivmod__(self, other):
try:
other = Number(other)
except TypeError:
return NotImplemented
return divmod(other, self)
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 __floor__(self):
return self.floor()
def __ceil__(self):
return self.ceiling()
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_parameters.evaluate:
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_parameters.evaluate:
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_parameters.evaluate:
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 __truediv__(self, other):
if isinstance(other, Number) and global_parameters.evaluate:
if other is S.NaN:
return S.NaN
elif other is S.Infinity or other is S.NegativeInfinity:
return S.Zero
return AtomicExpr.__truediv__(self, other)
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().__hash__()
def is_constant(self, *wrt, **flags):
return True
def as_coeff_mul(self, *deps, rational=True, **kwargs):
# a -> c*t
if self.is_Rational or not rational:
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; spaces or underscores are also allowed. (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.
In SymPy, a Float is a number that can be computed with arbitrary
precision. Although floating point 'inf' and 'nan' are not such
numbers, Float can create these numbers:
>>> Float('-inf')
-oo
>>> _.is_Float
False
"""
__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_extended_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, str):
# Float accepts spaces as digit separators
num = num.replace(' ', '').lower()
# in Py 3.6
# underscores are allowed. In anticipation of that, we ignore
# legally placed underscores
if '_' in num:
parts = num.split('_')
if not (all(parts) and
all(parts[i][-1].isdigit()
for i in range(0, len(parts), 2)) and
all(parts[i][0].isdigit()
for i in range(1, len(parts), 2))):
# copy Py 3.6 error
raise ValueError("could not convert string to float: '%s'" % num)
num = ''.join(parts)
if num.startswith('.') and len(num) > 1:
num = '0' + num
elif num.startswith('-.') and len(num) > 2:
num = '-0.' + num[2:]
elif num in ('inf', '+inf'):
return S.Infinity
elif num == '-inf':
return S.NegativeInfinity
elif isinstance(num, float) and num == 0:
num = '0'
elif isinstance(num, float) and num == float('inf'):
return S.Infinity
elif isinstance(num, float) and num == float('-inf'):
return S.NegativeInfinity
elif isinstance(num, float) and num == float('nan'):
return S.NaN
elif isinstance(num, (SYMPY_INTS, Integer)):
num = str(num)
elif num is S.Infinity:
return num
elif num is S.NegativeInfinity:
return num
elif num is S.NaN:
return num
elif _is_numpy_instance(num): # 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, str) 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, str):
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, str):
_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():
return S.NaN
elif num.is_infinite():
if num > 0:
return S.Infinity
return S.NegativeInfinity
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:
if not all((
num[0] in (0, 1),
num[1] >= 0,
all(type(i) in (int, int) for i in num)
)):
raise ValueError('malformed mpf: %s' % (num,))
# don't compute number or else it may
# over/underflow
return Float._new(
(num[0], num[1], num[2], bitcount(num[1])),
precision)
else:
try:
_mpf_ = num._as_mpf_val(precision)
except (NotImplementedError, AttributeError):
_mpf_ = mpmath.mpf(num, prec=precision)._mpf_
return cls._new(_mpf_, precision, zero=False)
@classmethod
def _new(cls, _mpf_, _prec, zero=True):
# special cases
if zero and _mpf_ == fzero:
return S.Zero # Float(0) -> 0.0; Float._new((0,0,0,0)) -> 0
elif _mpf_ == _mpf_nan:
return S.NaN
elif _mpf_ == _mpf_inf:
return S.Infinity
elif _mpf_ == _mpf_ninf:
return S.NegativeInfinity
obj = Expr.__new__(cls)
obj._mpf_ = mpf_norm(_mpf_, _prec)
obj._prec = _prec
return obj
# mpz can't be pickled
def __getnewargs_ex__(self):
return ((mlib.to_pickable(self._mpf_),), {'precision': 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))))
def __floor__(self):
return self.floor()
def __ceil__(self):
return self.ceiling()
@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_ == fzero
def _eval_is_negative(self):
if self._mpf_ == _mpf_ninf or self._mpf_ == _mpf_inf:
return False
return self.num < 0
def _eval_is_positive(self):
if self._mpf_ == _mpf_ninf or self._mpf_ == _mpf_inf:
return False
return self.num > 0
def _eval_is_extended_negative(self):
if self._mpf_ == _mpf_ninf:
return True
if self._mpf_ == _mpf_inf:
return False
return self.num < 0
def _eval_is_extended_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_ == fzero
def __bool__(self):
return self._mpf_ != fzero
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_parameters.evaluate:
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_parameters.evaluate:
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_parameters.evaluate:
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 __truediv__(self, other):
if isinstance(other, Number) and other != 0 and global_parameters.evaluate:
rhs, prec = other._as_mpf_op(self._prec)
return Float._new(mlib.mpf_div(self._mpf_, rhs, prec, rnd), prec)
return Number.__truediv__(self, other)
@_sympifyit('other', NotImplemented)
def __mod__(self, other):
if isinstance(other, Rational) and other.q != 1 and global_parameters.evaluate:
# calculate mod with Rationals, *then* round the result
return Float(Rational.__mod__(Rational(self), other),
precision=self._prec)
if isinstance(other, Float) and global_parameters.evaluate:
r = self/other
if r == int(r):
return Float(0, precision=max(self._prec, other._prec))
if isinstance(other, Number) and global_parameters.evaluate:
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_parameters.evaluate:
return other.__mod__(self)
if isinstance(other, Number) and global_parameters.evaluate:
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 S.Infinity
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, fzero), (expt, fzero), 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_ == fzero:
return 0
return int(mlib.to_int(self._mpf_)) # uses round_fast = round_down
def __eq__(self, other):
from sympy.logic.boolalg import Boolean
try:
other = _sympify(other)
except SympifyError:
return NotImplemented
if isinstance(other, Boolean):
return False
if other.is_NumberSymbol:
if other.is_irrational:
return False
return other.__eq__(self)
if other.is_Float:
# comparison is exact
# so Float(.1, 3) != Float(.1, 33)
return self._mpf_ == other._mpf_
if other.is_Rational:
return other.__eq__(self)
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))
if not self:
return not other
return False # Float != non-Number
def __ne__(self, other):
return not self == other
def _Frel(self, other, op):
from sympy.core.numbers import prec_to_dps
try:
other = _sympify(other)
except SympifyError:
return NotImplemented
if other.is_Rational:
# test self*other.q <?> other.p without losing precision
'''
>>> f = Float(.1,2)
>>> i = 1234567890
>>> (f*i)._mpf_
(0, 471, 18, 9)
>>> mlib.mpf_mul(f._mpf_, mlib.from_int(i))
(0, 505555550955, -12, 39)
'''
smpf = mlib.mpf_mul(self._mpf_, mlib.from_int(other.q))
ompf = mlib.from_int(other.p)
return _sympify(bool(op(smpf, ompf)))
elif other.is_Float:
return _sympify(bool(
op(self._mpf_, other._mpf_)))
elif other.is_comparable and other not in (
S.Infinity, S.NegativeInfinity):
other = other.evalf(prec_to_dps(self._prec))
if other._prec > 1:
if other.is_Number:
return _sympify(bool(
op(self._mpf_, other._as_mpf_val(self._prec))))
def __gt__(self, other):
if isinstance(other, NumberSymbol):
return other.__lt__(self)
rv = self._Frel(other, mlib.mpf_gt)
if rv is None:
return Expr.__gt__(self, other)
return rv
def __ge__(self, other):
if isinstance(other, NumberSymbol):
return other.__le__(self)
rv = self._Frel(other, mlib.mpf_ge)
if rv is None:
return Expr.__ge__(self, other)
return rv
def __lt__(self, other):
if isinstance(other, NumberSymbol):
return other.__gt__(self)
rv = self._Frel(other, mlib.mpf_lt)
if rv is None:
return Expr.__lt__(self, other)
return rv
def __le__(self, other):
if isinstance(other, NumberSymbol):
return other.__ge__(self)
rv = self._Frel(other, mlib.mpf_le)
if rv is None:
return Expr.__le__(self, other)
return rv
def __hash__(self):
return super().__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
========
sympy.core.sympify.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, str):
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.
Examples
========
>>> 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_parameters.evaluate:
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_parameters.evaluate:
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_parameters.evaluate:
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_parameters.evaluate:
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 __truediv__(self, other):
if global_parameters.evaluate:
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.__truediv__(self, other)
return Number.__truediv__(self, other)
@_sympifyit('other', NotImplemented)
def __rtruediv__(self, other):
if global_parameters.evaluate:
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.__rtruediv__(self, other)
return Number.__rtruediv__(self, other)
@_sympifyit('other', NotImplemented)
def __mod__(self, other):
if global_parameters.evaluate:
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_extended_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_extended_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)
def floor(self):
return Integer(self.p // self.q)
def ceiling(self):
return -Integer(-self.p // self.q)
def __floor__(self):
return self.floor()
def __ceil__(self):
return self.ceiling()
def __eq__(self, other):
from sympy.core.power import integer_log
try:
other = _sympify(other)
except SympifyError:
return NotImplemented
if not isinstance(other, Number):
# S(0) == S.false is False
# S(0) == False is True
return False
if not self:
return not other
if other.is_NumberSymbol:
if other.is_irrational:
return False
return other.__eq__(self)
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:
# all Floats have a denominator that is a power of 2
# so if self doesn't, it can't be equal to other
if self.q & (self.q - 1):
return False
s, m, t = other._mpf_[:3]
if s:
m = -m
if not t:
# other is an odd integer
if not self.is_Integer or self.is_even:
return False
return m == self.p
if t > 0:
# other is an even integer
if not self.is_Integer:
return False
# does m*2**t == self.p
return self.p and not self.p % m and \
integer_log(self.p//m, 2) == (t, True)
# does non-integer s*m/2**-t = p/q?
if self.is_Integer:
return False
return m == self.p and integer_log(self.q, 2) == (-t, True)
return False
def __ne__(self, other):
return not self == other
def _Rrel(self, other, attr):
# if you want self < other, pass self, other, __gt__
try:
other = _sympify(other)
except SympifyError:
return NotImplemented
if other.is_Number:
op = None
s, o = self, other
if other.is_NumberSymbol:
op = getattr(o, attr)
elif other.is_Float:
op = getattr(o, attr)
elif other.is_Rational:
s, o = Integer(s.p*o.q), Integer(s.q*o.p)
op = getattr(o, attr)
if op:
return op(s)
if o.is_number and o.is_extended_real:
return Integer(s.p), s.q*o
def __gt__(self, other):
rv = self._Rrel(other, '__lt__')
if rv is None:
rv = self, other
elif not type(rv) is tuple:
return rv
return Expr.__gt__(*rv)
def __ge__(self, other):
rv = self._Rrel(other, '__le__')
if rv is None:
rv = self, other
elif not type(rv) is tuple:
return rv
return Expr.__ge__(*rv)
def __lt__(self, other):
rv = self._Rrel(other, '__gt__')
if rv is None:
rv = self, other
elif not type(rv) is tuple:
return rv
return Expr.__lt__(*rv)
def __le__(self, other):
rv = self._Rrel(other, '__ge__')
if rv is None:
rv = self, other
elif not type(rv) is tuple:
return rv
return Expr.__le__(*rv)
def __hash__(self):
return super().__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()
@property
def numerator(self):
return self.p
@property
def denominator(self):
return self.q
@_sympifyit('other', NotImplemented)
def gcd(self, other):
if isinstance(other, Rational):
if other == 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
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))
@cacheit
def __new__(cls, i):
if isinstance(i, str):
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)
# We only work with well-behaved integer types. This converts, for
# example, numpy.int32 instances.
if ival == 1:
return S.One
if ival == -1:
return S.NegativeOne
if ival == 0:
return S.Zero
obj = Expr.__new__(cls)
obj.p = ival
return obj
def __getnewargs__(self):
return (self.p,)
# Arithmetic operations are here for efficiency
def __int__(self):
return self.p
def floor(self):
return Integer(self.p)
def ceiling(self):
return Integer(self.p)
def __floor__(self):
return self.floor()
def __ceil__(self):
return self.ceiling()
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_parameters.evaluate:
return Tuple(*(divmod(self.p, other.p)))
else:
return Number.__divmod__(self, other)
def __rdivmod__(self, other):
from .containers import Tuple
if isinstance(other, int) and global_parameters.evaluate:
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_parameters.evaluate:
if isinstance(other, int):
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_parameters.evaluate:
if isinstance(other, int):
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_parameters.evaluate:
if isinstance(other, int):
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_parameters.evaluate:
if isinstance(other, int):
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_parameters.evaluate:
if isinstance(other, int):
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_parameters.evaluate:
if isinstance(other, int):
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_parameters.evaluate:
if isinstance(other, int):
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_parameters.evaluate:
if isinstance(other, int):
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, int):
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:
return NotImplemented
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:
return NotImplemented
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:
return NotImplemented
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:
return NotImplemented
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.
Explanation
===========
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.ntheory.factor_ 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()._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
@_sympifyit('other', NotImplemented)
def __floordiv__(self, other):
if not isinstance(other, Expr):
return NotImplemented
if isinstance(other, Integer):
return Integer(self.p // other)
return Integer(divmod(self, other)[0])
def __rfloordiv__(self, other):
return Integer(Integer(other).p // self.p)
# These bitwise operations (__lshift__, __rlshift__, ..., __invert__) are defined
# for Integer only and not for general sympy expressions. This is to achieve
# compatibility with the numbers.Integral ABC which only defines these operations
# among instances of numbers.Integral. Therefore, these methods check explicitly for
# integer types rather than using sympify because they should not accept arbitrary
# symbolic expressions and there is no symbolic analogue of numbers.Integral's
# bitwise operations.
def __lshift__(self, other):
if isinstance(other, (int, Integer, numbers.Integral)):
return Integer(self.p << int(other))
else:
return NotImplemented
def __rlshift__(self, other):
if isinstance(other, (int, numbers.Integral)):
return Integer(int(other) << self.p)
else:
return NotImplemented
def __rshift__(self, other):
if isinstance(other, (int, Integer, numbers.Integral)):
return Integer(self.p >> int(other))
else:
return NotImplemented
def __rrshift__(self, other):
if isinstance(other, (int, numbers.Integral)):
return Integer(int(other) >> self.p)
else:
return NotImplemented
def __and__(self, other):
if isinstance(other, (int, Integer, numbers.Integral)):
return Integer(self.p & int(other))
else:
return NotImplemented
def __rand__(self, other):
if isinstance(other, (int, numbers.Integral)):
return Integer(int(other) & self.p)
else:
return NotImplemented
def __xor__(self, other):
if isinstance(other, (int, Integer, numbers.Integral)):
return Integer(self.p ^ int(other))
else:
return NotImplemented
def __rxor__(self, other):
if isinstance(other, (int, numbers.Integral)):
return Integer(int(other) ^ self.p)
else:
return NotImplemented
def __or__(self, other):
if isinstance(other, (int, Integer, numbers.Integral)):
return Integer(self.p | int(other))
else:
return NotImplemented
def __ror__(self, other):
if isinstance(other, (int, numbers.Integral)):
return Integer(int(other) | self.p)
else:
return NotImplemented
def __invert__(self):
return Integer(~self.p)
# Add sympify converters
converter[int] = 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
kind = NumberKind
# Optional alias symbol is not free.
# Actually, alias should be a Str, but some methods
# expect that it be an instance of Expr.
free_symbols = set()
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().__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, **kwargs):
from sympy.polys import CRootOf, minpoly
measure, ratio = kwargs['measure'], kwargs['ratio']
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(IntegerConstant, metaclass=Singleton):
"""The number zero.
Zero is a singleton, and can be accessed by ``S.Zero``
Examples
========
>>> from sympy import S, Integer
>>> 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
is_comparable = True
__slots__ = ()
def __getnewargs__(self):
return ()
@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_extended_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 __bool__(self):
return False
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(IntegerConstant, metaclass=Singleton):
"""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
is_positive = True
p = 1
q = 1
__slots__ = ()
def __getnewargs__(self):
return ()
@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(IntegerConstant, metaclass=Singleton):
"""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__ = ()
def __getnewargs__(self):
return ()
@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(RationalConstant, metaclass=Singleton):
"""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__ = ()
def __getnewargs__(self):
return ()
@staticmethod
def __abs__():
return S.Half
class Infinity(Number, metaclass=Singleton):
r"""Positive infinite quantity.
Explanation
===========
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_number = True
is_complex = False
is_extended_real = True
is_infinite = True
is_comparable = True
is_extended_positive = 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
def _eval_evalf(self, prec=None):
return Float('inf')
def evalf(self, prec=None, **options):
return self._eval_evalf(prec)
@_sympifyit('other', NotImplemented)
def __add__(self, other):
if isinstance(other, Number) and global_parameters.evaluate:
if other is S.NegativeInfinity or other is S.NaN:
return S.NaN
return self
return Number.__add__(self, other)
__radd__ = __add__
@_sympifyit('other', NotImplemented)
def __sub__(self, other):
if isinstance(other, Number) and global_parameters.evaluate:
if other is S.Infinity or other is S.NaN:
return S.NaN
return self
return Number.__sub__(self, other)
@_sympifyit('other', NotImplemented)
def __rsub__(self, other):
return (-self).__add__(other)
@_sympifyit('other', NotImplemented)
def __mul__(self, other):
if isinstance(other, Number) and global_parameters.evaluate:
if other.is_zero or other is S.NaN:
return S.NaN
if other.is_extended_positive:
return self
return S.NegativeInfinity
return Number.__mul__(self, other)
__rmul__ = __mul__
@_sympifyit('other', NotImplemented)
def __truediv__(self, other):
if isinstance(other, Number) and global_parameters.evaluate:
if other is S.Infinity or \
other is S.NegativeInfinity or \
other is S.NaN:
return S.NaN
if other.is_extended_nonnegative:
return self
return S.NegativeInfinity
return Number.__truediv__(self, other)
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_extended_positive:
return S.Infinity
if expt.is_extended_negative:
return S.Zero
if expt is S.NaN:
return S.NaN
if expt is S.ComplexInfinity:
return S.NaN
if expt.is_extended_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().__hash__()
def __eq__(self, other):
return other is S.Infinity or other == float('inf')
def __ne__(self, other):
return other is not S.Infinity and other != float('inf')
__gt__ = Expr.__gt__
__ge__ = Expr.__ge__
__lt__ = Expr.__lt__
__le__ = Expr.__le__
@_sympifyit('other', NotImplemented)
def __mod__(self, other):
if not isinstance(other, Expr):
return NotImplemented
return S.NaN
__rmod__ = __mod__
def floor(self):
return self
def ceiling(self):
return self
oo = S.Infinity
class NegativeInfinity(Number, metaclass=Singleton):
"""Negative infinite quantity.
NegativeInfinity is a singleton, and can be accessed
by ``S.NegativeInfinity``.
See Also
========
Infinity
"""
is_extended_real = True
is_complex = False
is_commutative = True
is_infinite = True
is_comparable = True
is_extended_negative = 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
def _eval_evalf(self, prec=None):
return Float('-inf')
def evalf(self, prec=None, **options):
return self._eval_evalf(prec)
@_sympifyit('other', NotImplemented)
def __add__(self, other):
if isinstance(other, Number) and global_parameters.evaluate:
if other is S.Infinity or other is S.NaN:
return S.NaN
return self
return Number.__add__(self, other)
__radd__ = __add__
@_sympifyit('other', NotImplemented)
def __sub__(self, other):
if isinstance(other, Number) and global_parameters.evaluate:
if other is S.NegativeInfinity or other is S.NaN:
return S.NaN
return self
return Number.__sub__(self, other)
@_sympifyit('other', NotImplemented)
def __rsub__(self, other):
return (-self).__add__(other)
@_sympifyit('other', NotImplemented)
def __mul__(self, other):
if isinstance(other, Number) and global_parameters.evaluate:
if other.is_zero or other is S.NaN:
return S.NaN
if other.is_extended_positive:
return self
return S.Infinity
return Number.__mul__(self, other)
__rmul__ = __mul__
@_sympifyit('other', NotImplemented)
def __truediv__(self, other):
if isinstance(other, Number) and global_parameters.evaluate:
if other is S.Infinity or \
other is S.NegativeInfinity or \
other is S.NaN:
return S.NaN
if other.is_extended_nonnegative:
return self
return S.Infinity
return Number.__truediv__(self, other)
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_extended_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().__hash__()
def __eq__(self, other):
return other is S.NegativeInfinity or other == float('-inf')
def __ne__(self, other):
return other is not S.NegativeInfinity and other != float('-inf')
__gt__ = Expr.__gt__
__ge__ = Expr.__ge__
__lt__ = Expr.__lt__
__le__ = Expr.__le__
@_sympifyit('other', NotImplemented)
def __mod__(self, other):
if not isinstance(other, Expr):
return NotImplemented
return S.NaN
__rmod__ = __mod__
def floor(self):
return self
def ceiling(self):
return self
def as_powers_dict(self):
return {S.NegativeOne: 1, S.Infinity: 1}
class NaN(Number, metaclass=Singleton):
"""
Not a Number.
Explanation
===========
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
contrast 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_extended_real = None
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"\text{NaN}"
def __neg__(self):
return self
@_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 __truediv__(self, other):
return self
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().__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
# Expr will _sympify and raise TypeError
__gt__ = Expr.__gt__
__ge__ = Expr.__ge__
__lt__ = Expr.__lt__
__le__ = Expr.__le__
nan = S.NaN
@dispatch(NaN, Expr) # type:ignore
def _eval_is_eq(a, b): # noqa:F811
return False
class ComplexInfinity(AtomicExpr, metaclass=Singleton):
r"""Complex infinity.
Explanation
===========
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
>>> 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 = False
is_extended_real = False
kind = NumberKind
__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_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
kind = NumberKind
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 __hash__(self):
return super().__hash__()
class Exp1(NumberSymbol, metaclass=Singleton):
r"""The `e` constant.
Explanation
===========
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
if global_parameters.exp_is_pow:
return self._eval_power_exp_is_pow(expt)
else:
return exp(expt)
def _eval_power_exp_is_pow(self, arg):
from ..functions.elementary.exponential import log
from . import Add, Mul, Pow
if arg.is_Number:
if arg is oo:
return oo
elif arg == -oo:
return S.Zero
elif isinstance(arg, log):
return arg.args[0]
# don't autoexpand Pow or Mul (see the issue 3351):
elif not arg.is_Add:
Ioo = I*oo
if arg in [Ioo, -Ioo]:
return nan
coeff = arg.coeff(pi*I)
if coeff:
if (2*coeff).is_integer:
if coeff.is_even:
return S.One
elif coeff.is_odd:
return S.NegativeOne
elif (coeff + S.Half).is_even:
return -I
elif (coeff + S.Half).is_odd:
return I
elif coeff.is_Rational:
ncoeff = coeff % 2 # restrict to [0, 2pi)
if ncoeff > 1: # restrict to (-pi, pi]
ncoeff -= 2
if ncoeff != coeff:
return S.Exp1**(ncoeff*S.Pi*S.ImaginaryUnit)
# Warning: code in risch.py will be very sensitive to changes
# in this (see DifferentialExtension).
# look for a single log factor
coeff, terms = arg.as_coeff_Mul()
# but it can't be multiplied by oo
if coeff in (oo, -oo):
return
coeffs, log_term = [coeff], None
for term in Mul.make_args(terms):
if isinstance(term, log):
if log_term is None:
log_term = term.args[0]
else:
return
elif term.is_comparable:
coeffs.append(term)
else:
return
return log_term**Mul(*coeffs) if log_term else None
elif arg.is_Add:
out = []
add = []
argchanged = False
for a in arg.args:
if a is S.One:
add.append(a)
continue
newa = self**a
if isinstance(newa, Pow) and newa.base is self:
if newa.exp != a:
add.append(newa.exp)
argchanged = True
else:
add.append(a)
else:
out.append(newa)
if out or argchanged:
return Mul(*out)*Pow(self, Add(*add), evaluate=False)
elif arg.is_Matrix:
return arg.exp()
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(NumberSymbol, metaclass=Singleton):
r"""The `\pi` constant.
Explanation
===========
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(NumberSymbol, metaclass=Singleton):
r"""The golden ratio, `\phi`.
Explanation
===========
`\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(NumberSymbol, metaclass=Singleton):
r"""The tribonacci constant.
Explanation
===========
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 + (19 - 3*sqrt(33))**(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"\text{TribonacciConstant}"
def __int__(self):
return 1
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(NumberSymbol, metaclass=Singleton):
r"""The Euler-Mascheroni constant.
Explanation
===========
`\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(NumberSymbol, metaclass=Singleton):
r"""Catalan's constant.
Explanation
===========
`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 _eval_rewrite_as_Sum(self, k_sym=None, symbols=None):
from sympy import Sum, Dummy
if (k_sym is not None) or (symbols is not None):
return self
k = Dummy('k', integer=True, nonnegative=True)
return Sum((-1)**k / (2*k+1)**2, (k, 0, S.Infinity))
def _sage_(self):
import sage.all as sage
return sage.catalan
class ImaginaryUnit(AtomicExpr, metaclass=Singleton):
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
kind = NumberKind
__slots__ = ()
def _latex(self, printer):
return printer._settings['imaginary_unit_latex']
@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, Integer):
expt = expt % 4
if expt == 0:
return S.One
elif expt == 1:
return S.ImaginaryUnit
elif expt == 2:
return S.NegativeOne
elif expt == 3:
return -S.ImaginaryUnit
if isinstance(expt, Rational):
i, r = divmod(expt, 2)
rv = Pow(S.ImaginaryUnit, r, evaluate=False)
if i % 2:
return Mul(S.NegativeOne, rv, evaluate=False)
return rv
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
@dispatch(Tuple, Number) # type:ignore
def _eval_is_eq(self, other): # noqa: F811
return False
def sympify_fractions(f):
return Rational(f.numerator, f.denominator, 1)
converter[fractions.Fraction] = sympify_fractions
if HAS_GMPY:
def sympify_mpz(x):
return Integer(int(x))
# XXX: The sympify_mpq function here was never used because it is
# overridden by the other sympify_mpq function below. Maybe it should just
# be removed or maybe it should be used for something...
def sympify_mpq(x):
return Rational(int(x.numerator), int(x.denominator))
converter[type(gmpy.mpz(1))] = sympify_mpz
converter[type(gmpy.mpq(1, 2))] = sympify_mpq
def sympify_mpmath_mpq(x):
p, q = x._mpq_
return Rational(p, q, 1)
converter[type(mpmath.rational.mpq(1, 2))] = sympify_mpmath_mpq
def sympify_mpmath(x):
return Expr._from_mpmath(x, x.context.prec)
converter[mpnumeric] = sympify_mpmath
def sympify_complex(a):
real, imag = list(map(sympify, (a.real, a.imag)))
return real + S.ImaginaryUnit*imag
converter[complex] = sympify_complex
from .power import Pow, integer_nthroot
from .mul import Mul
Mul.identity = One()
from .add import Add
Add.identity = Zero()
def _register_classes():
numbers.Number.register(Number)
numbers.Real.register(Float)
numbers.Rational.register(Rational)
numbers.Integral.register(Integer)
_register_classes()
|
fd539de662d311540c5b084e47b7caa318a03c64bf65a82c1542d946e480e79c | """ Caching facility for SymPy """
class _cache(list):
""" List of cached functions """
def print_cache(self):
"""print cache info"""
for item in self:
name = item.__name__
myfunc = item
while hasattr(myfunc, '__wrapped__'):
if hasattr(myfunc, 'cache_info'):
info = myfunc.cache_info()
break
else:
myfunc = myfunc.__wrapped__
else:
info = None
print(name, info)
def clear_cache(self):
"""clear cache content"""
for item in self:
myfunc = item
while hasattr(myfunc, '__wrapped__'):
if hasattr(myfunc, 'cache_clear'):
myfunc.cache_clear()
break
else:
myfunc = myfunc.__wrapped__
# global cache registry:
CACHE = _cache()
# make clear and print methods available
print_cache = CACHE.print_cache
clear_cache = CACHE.clear_cache
from functools import lru_cache
def __cacheit(maxsize):
"""caching decorator.
important: the result of cached function must be *immutable*
Examples
========
>>> from sympy.core.cache import cacheit
>>> @cacheit
... def f(a, b):
... return a+b
>>> @cacheit
... def f(a, b): # noqa: F811
... return [a, b] # <-- WRONG, returns mutable object
to force cacheit to check returned results mutability and consistency,
set environment variable SYMPY_USE_CACHE to 'debug'
"""
def func_wrapper(func):
from .decorators import wraps
cfunc = lru_cache(maxsize, typed=True)(func)
@wraps(func)
def wrapper(*args, **kwargs):
try:
retval = cfunc(*args, **kwargs)
except TypeError as e:
if not e.args or not e.args[0].startswith('unhashable type:'):
raise
retval = func(*args, **kwargs)
return retval
wrapper.cache_info = cfunc.cache_info
wrapper.cache_clear = cfunc.cache_clear
CACHE.append(wrapper)
return wrapper
return func_wrapper
########################################
def __cacheit_nocache(func):
return func
def __cacheit_debug(maxsize):
"""cacheit + code to check cache consistency"""
def func_wrapper(func):
from .decorators import wraps
cfunc = __cacheit(maxsize)(func)
@wraps(func)
def wrapper(*args, **kw_args):
# always call function itself and compare it with cached version
r1 = func(*args, **kw_args)
r2 = cfunc(*args, **kw_args)
# try to see if the result is immutable
#
# this works because:
#
# hash([1,2,3]) -> raise TypeError
# hash({'a':1, 'b':2}) -> raise TypeError
# hash((1,[2,3])) -> raise TypeError
#
# hash((1,2,3)) -> just computes the hash
hash(r1), hash(r2)
# also see if returned values are the same
if r1 != r2:
raise RuntimeError("Returned values are not the same")
return r1
return wrapper
return func_wrapper
def _getenv(key, default=None):
from os import getenv
return getenv(key, default)
# SYMPY_USE_CACHE=yes/no/debug
USE_CACHE = _getenv('SYMPY_USE_CACHE', 'yes').lower()
# SYMPY_CACHE_SIZE=some_integer/None
# special cases :
# SYMPY_CACHE_SIZE=0 -> No caching
# SYMPY_CACHE_SIZE=None -> Unbounded caching
scs = _getenv('SYMPY_CACHE_SIZE', '1000')
if scs.lower() == 'none':
SYMPY_CACHE_SIZE = None
else:
try:
SYMPY_CACHE_SIZE = int(scs)
except ValueError:
raise RuntimeError(
'SYMPY_CACHE_SIZE must be a valid integer or None. ' + \
'Got: %s' % SYMPY_CACHE_SIZE)
if USE_CACHE == 'no':
cacheit = __cacheit_nocache
elif USE_CACHE == 'yes':
cacheit = __cacheit(SYMPY_CACHE_SIZE)
elif USE_CACHE == 'debug':
cacheit = __cacheit_debug(SYMPY_CACHE_SIZE) # a lot slower
else:
raise RuntimeError(
'unrecognized value for SYMPY_USE_CACHE: %s' % USE_CACHE)
|
82801f9bf2381d49fe5dfa8674f7586d38e09d3f5e5bc7f971a0cc9f75d76f73 | from collections import defaultdict
from functools import cmp_to_key, reduce
import operator
from .sympify import sympify
from .basic import Basic
from .singleton import S
from .operations import AssocOp, AssocOpDispatcher
from .cache import cacheit
from .logic import fuzzy_not, _fuzzy_group
from .expr import Expr
from .parameters import global_parameters
from .kind import KindDispatcher
# internal marker to indicate:
# "there are still non-commutative objects -- don't forget to process them"
class NC_Marker:
is_Order = False
is_Mul = False
is_Number = False
is_Poly = False
is_commutative = False
# Key for sorting commutative args in canonical order
_args_sortkey = cmp_to_key(Basic.compare)
def _mulsort(args):
# in-place sorting of args
args.sort(key=_args_sortkey)
def _unevaluated_Mul(*args):
"""Return a well-formed unevaluated Mul: Numbers are collected and
put in slot 0, any arguments that are Muls will be flattened, and args
are sorted. Use this when args have changed but you still want to return
an unevaluated Mul.
Examples
========
>>> from sympy.core.mul import _unevaluated_Mul as uMul
>>> from sympy import S, sqrt, Mul
>>> from sympy.abc import x
>>> a = uMul(*[S(3.0), x, S(2)])
>>> a.args[0]
6.00000000000000
>>> a.args[1]
x
Two unevaluated Muls with the same arguments will
always compare as equal during testing:
>>> m = uMul(sqrt(2), sqrt(3))
>>> m == uMul(sqrt(3), sqrt(2))
True
>>> u = Mul(sqrt(3), sqrt(2), evaluate=False)
>>> m == uMul(u)
True
>>> m == Mul(*m.args)
False
"""
args = list(args)
newargs = []
ncargs = []
co = S.One
while args:
a = args.pop()
if a.is_Mul:
c, nc = a.args_cnc()
args.extend(c)
if nc:
ncargs.append(Mul._from_args(nc))
elif a.is_Number:
co *= a
else:
newargs.append(a)
_mulsort(newargs)
if co is not S.One:
newargs.insert(0, co)
if ncargs:
newargs.append(Mul._from_args(ncargs))
return Mul._from_args(newargs)
class Mul(Expr, AssocOp):
"""
Expression representing multiplication operation for algebraic field.
Every argument of ``Mul()`` must be ``Expr``. Infix operator ``*``
on most scalar objects in SymPy calls this class.
Another use of ``Mul()`` is to represent the structure of abstract
multiplication so that its arguments can be substituted to return
different class. Refer to examples section for this.
``Mul()`` evaluates the argument unless ``evaluate=False`` is passed.
The evaluation logic includes:
1. Flattening
``Mul(x, Mul(y, z))`` -> ``Mul(x, y, z)``
2. Identity removing
``Mul(x, 1, y)`` -> ``Mul(x, y)``
3. Exponent collecting by ``.as_base_exp()``
``Mul(x, x**2)`` -> ``Pow(x, 3)``
4. Term sorting
``Mul(y, x, 2)`` -> ``Mul(2, x, y)``
Since multiplication can be vector space operation, arguments may
have the different :obj:`sympy.core.kind.Kind()`. Kind of the
resulting object is automatically inferred.
Examples
========
>>> from sympy import Mul
>>> from sympy.abc import x, y
>>> Mul(x, 1)
x
>>> Mul(x, x)
x**2
If ``evaluate=False`` is passed, result is not evaluated.
>>> Mul(1, 2, evaluate=False)
1*2
>>> Mul(x, x, evaluate=False)
x*x
``Mul()`` also represents the general structure of multiplication
operation.
>>> from sympy import MatrixSymbol
>>> A = MatrixSymbol('A', 2,2)
>>> expr = Mul(x,y).subs({y:A})
>>> expr
x*A
>>> type(expr)
<class 'sympy.matrices.expressions.matmul.MatMul'>
See Also
========
MatMul
"""
__slots__ = ()
is_Mul = True
_args_type = Expr
_kind_dispatcher = KindDispatcher("Mul_kind_dispatcher", commutative=True)
@property
def kind(self):
arg_kinds = (a.kind for a in self.args)
return self._kind_dispatcher(*arg_kinds)
def __neg__(self):
c, args = self.as_coeff_mul()
c = -c
if c is not S.One:
if args[0].is_Number:
args = list(args)
if c is S.NegativeOne:
args[0] = -args[0]
else:
args[0] *= c
else:
args = (c,) + args
return self._from_args(args, self.is_commutative)
@classmethod
def flatten(cls, seq):
"""Return commutative, noncommutative and order arguments by
combining related terms.
Notes
=====
* In an expression like ``a*b*c``, python process this through sympy
as ``Mul(Mul(a, b), c)``. This can have undesirable consequences.
- Sometimes terms are not combined as one would like:
{c.f. https://github.com/sympy/sympy/issues/4596}
>>> from sympy import Mul, sqrt
>>> from sympy.abc import x, y, z
>>> 2*(x + 1) # this is the 2-arg Mul behavior
2*x + 2
>>> y*(x + 1)*2
2*y*(x + 1)
>>> 2*(x + 1)*y # 2-arg result will be obtained first
y*(2*x + 2)
>>> Mul(2, x + 1, y) # all 3 args simultaneously processed
2*y*(x + 1)
>>> 2*((x + 1)*y) # parentheses can control this behavior
2*y*(x + 1)
Powers with compound bases may not find a single base to
combine with unless all arguments are processed at once.
Post-processing may be necessary in such cases.
{c.f. https://github.com/sympy/sympy/issues/5728}
>>> a = sqrt(x*sqrt(y))
>>> a**3
(x*sqrt(y))**(3/2)
>>> Mul(a,a,a)
(x*sqrt(y))**(3/2)
>>> a*a*a
x*sqrt(y)*sqrt(x*sqrt(y))
>>> _.subs(a.base, z).subs(z, a.base)
(x*sqrt(y))**(3/2)
- If more than two terms are being multiplied then all the
previous terms will be re-processed for each new argument.
So if each of ``a``, ``b`` and ``c`` were :class:`Mul`
expression, then ``a*b*c`` (or building up the product
with ``*=``) will process all the arguments of ``a`` and
``b`` twice: once when ``a*b`` is computed and again when
``c`` is multiplied.
Using ``Mul(a, b, c)`` will process all arguments once.
* The results of Mul are cached according to arguments, so flatten
will only be called once for ``Mul(a, b, c)``. If you can
structure a calculation so the arguments are most likely to be
repeats then this can save time in computing the answer. For
example, say you had a Mul, M, that you wished to divide by ``d[i]``
and multiply by ``n[i]`` and you suspect there are many repeats
in ``n``. It would be better to compute ``M*n[i]/d[i]`` rather
than ``M/d[i]*n[i]`` since every time n[i] is a repeat, the
product, ``M*n[i]`` will be returned without flattening -- the
cached value will be returned. If you divide by the ``d[i]``
first (and those are more unique than the ``n[i]``) then that will
create a new Mul, ``M/d[i]`` the args of which will be traversed
again when it is multiplied by ``n[i]``.
{c.f. https://github.com/sympy/sympy/issues/5706}
This consideration is moot if the cache is turned off.
NB
--
The validity of the above notes depends on the implementation
details of Mul and flatten which may change at any time. Therefore,
you should only consider them when your code is highly performance
sensitive.
Removal of 1 from the sequence is already handled by AssocOp.__new__.
"""
from sympy.calculus.util import AccumBounds
from sympy.matrices.expressions import MatrixExpr
rv = None
if len(seq) == 2:
a, b = seq
if b.is_Rational:
a, b = b, a
seq = [a, b]
assert not a is S.One
if not a.is_zero and a.is_Rational:
r, b = b.as_coeff_Mul()
if b.is_Add:
if r is not S.One: # 2-arg hack
# leave the Mul as a Mul?
ar = a*r
if ar is S.One:
arb = b
else:
arb = cls(a*r, b, evaluate=False)
rv = [arb], [], None
elif global_parameters.distribute and b.is_commutative:
r, b = b.as_coeff_Add()
bargs = [_keep_coeff(a, bi) for bi in Add.make_args(b)]
_addsort(bargs)
ar = a*r
if ar:
bargs.insert(0, ar)
bargs = [Add._from_args(bargs)]
rv = bargs, [], None
if rv:
return rv
# apply associativity, separate commutative part of seq
c_part = [] # out: commutative factors
nc_part = [] # out: non-commutative factors
nc_seq = []
coeff = S.One # standalone term
# e.g. 3 * ...
c_powers = [] # (base,exp) n
# e.g. (x,n) for x
num_exp = [] # (num-base, exp) y
# e.g. (3, y) for ... * 3 * ...
neg1e = S.Zero # exponent on -1 extracted from Number-based Pow and I
pnum_rat = {} # (num-base, Rat-exp) 1/2
# e.g. (3, 1/2) for ... * 3 * ...
order_symbols = None
# --- PART 1 ---
#
# "collect powers and coeff":
#
# o coeff
# o c_powers
# o num_exp
# o neg1e
# o pnum_rat
#
# NOTE: this is optimized for all-objects-are-commutative case
for o in seq:
# O(x)
if o.is_Order:
o, order_symbols = o.as_expr_variables(order_symbols)
# Mul([...])
if o.is_Mul:
if o.is_commutative:
seq.extend(o.args) # XXX zerocopy?
else:
# NCMul can have commutative parts as well
for q in o.args:
if q.is_commutative:
seq.append(q)
else:
nc_seq.append(q)
# append non-commutative marker, so we don't forget to
# process scheduled non-commutative objects
seq.append(NC_Marker)
continue
# 3
elif o.is_Number:
if o is S.NaN or coeff is S.ComplexInfinity and o.is_zero:
# we know for sure the result will be nan
return [S.NaN], [], None
elif coeff.is_Number or isinstance(coeff, AccumBounds): # it could be zoo
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.__mul__(coeff)
continue
elif o is S.ComplexInfinity:
if not coeff:
# 0 * zoo = NaN
return [S.NaN], [], None
coeff = S.ComplexInfinity
continue
elif o is S.ImaginaryUnit:
neg1e += S.Half
continue
elif o.is_commutative:
# e
# o = b
b, e = o.as_base_exp()
# y
# 3
if o.is_Pow:
if b.is_Number:
# get all the factors with numeric base so they can be
# combined below, but don't combine negatives unless
# the exponent is an integer
if e.is_Rational:
if e.is_Integer:
coeff *= Pow(b, e) # it is an unevaluated power
continue
elif e.is_negative: # also a sign of an unevaluated power
seq.append(Pow(b, e))
continue
elif b.is_negative:
neg1e += e
b = -b
if b is not S.One:
pnum_rat.setdefault(b, []).append(e)
continue
elif b.is_positive or e.is_integer:
num_exp.append((b, e))
continue
c_powers.append((b, e))
# NON-COMMUTATIVE
# TODO: Make non-commutative exponents not combine automatically
else:
if o is not NC_Marker:
nc_seq.append(o)
# process nc_seq (if any)
while nc_seq:
o = nc_seq.pop(0)
if not nc_part:
nc_part.append(o)
continue
# b c b+c
# try to combine last terms: a * a -> a
o1 = nc_part.pop()
b1, e1 = o1.as_base_exp()
b2, e2 = o.as_base_exp()
new_exp = e1 + e2
# Only allow powers to combine if the new exponent is
# not an Add. This allow things like a**2*b**3 == a**5
# if a.is_commutative == False, but prohibits
# a**x*a**y and x**a*x**b from combining (x,y commute).
if b1 == b2 and (not new_exp.is_Add):
o12 = b1 ** new_exp
# now o12 could be a commutative object
if o12.is_commutative:
seq.append(o12)
continue
else:
nc_seq.insert(0, o12)
else:
nc_part.append(o1)
nc_part.append(o)
# We do want a combined exponent if it would not be an Add, such as
# y 2y 3y
# x * x -> x
# We determine if two exponents have the same term by using
# as_coeff_Mul.
#
# Unfortunately, this isn't smart enough to consider combining into
# exponents that might already be adds, so things like:
# z - y y
# x * x will be left alone. This is because checking every possible
# combination can slow things down.
# gather exponents of common bases...
def _gather(c_powers):
common_b = {} # b:e
for b, e in c_powers:
co = e.as_coeff_Mul()
common_b.setdefault(b, {}).setdefault(
co[1], []).append(co[0])
for b, d in common_b.items():
for di, li in d.items():
d[di] = Add(*li)
new_c_powers = []
for b, e in common_b.items():
new_c_powers.extend([(b, c*t) for t, c in e.items()])
return new_c_powers
# in c_powers
c_powers = _gather(c_powers)
# and in num_exp
num_exp = _gather(num_exp)
# --- PART 2 ---
#
# o process collected powers (x**0 -> 1; x**1 -> x; otherwise Pow)
# o combine collected powers (2**x * 3**x -> 6**x)
# with numeric base
# ................................
# now we have:
# - coeff:
# - c_powers: (b, e)
# - num_exp: (2, e)
# - pnum_rat: {(1/3, [1/3, 2/3, 1/4])}
# 0 1
# x -> 1 x -> x
# this should only need to run twice; if it fails because
# it needs to be run more times, perhaps this should be
# changed to a "while True" loop -- the only reason it
# isn't such now is to allow a less-than-perfect result to
# be obtained rather than raising an error or entering an
# infinite loop
for i in range(2):
new_c_powers = []
changed = False
for b, e in c_powers:
if e.is_zero:
# canceling out infinities yields NaN
if (b.is_Add or b.is_Mul) and any(infty in b.args
for infty in (S.ComplexInfinity, S.Infinity,
S.NegativeInfinity)):
return [S.NaN], [], None
continue
if e is S.One:
if b.is_Number:
coeff *= b
continue
p = b
if e is not S.One:
p = Pow(b, e)
# check to make sure that the base doesn't change
# after exponentiation; to allow for unevaluated
# Pow, we only do so if b is not already a Pow
if p.is_Pow and not b.is_Pow:
bi = b
b, e = p.as_base_exp()
if b != bi:
changed = True
c_part.append(p)
new_c_powers.append((b, e))
# there might have been a change, but unless the base
# matches some other base, there is nothing to do
if changed and len({
b for b, e in new_c_powers}) != len(new_c_powers):
# start over again
c_part = []
c_powers = _gather(new_c_powers)
else:
break
# x x x
# 2 * 3 -> 6
inv_exp_dict = {} # exp:Mul(num-bases) x x
# e.g. x:6 for ... * 2 * 3 * ...
for b, e in num_exp:
inv_exp_dict.setdefault(e, []).append(b)
for e, b in inv_exp_dict.items():
inv_exp_dict[e] = cls(*b)
c_part.extend([Pow(b, e) for e, b in inv_exp_dict.items() if e])
# b, e -> e' = sum(e), b
# {(1/5, [1/3]), (1/2, [1/12, 1/4]} -> {(1/3, [1/5, 1/2])}
comb_e = {}
for b, e in pnum_rat.items():
comb_e.setdefault(Add(*e), []).append(b)
del pnum_rat
# process them, reducing exponents to values less than 1
# and updating coeff if necessary else adding them to
# num_rat for further processing
num_rat = []
for e, b in comb_e.items():
b = cls(*b)
if e.q == 1:
coeff *= Pow(b, e)
continue
if e.p > e.q:
e_i, ep = divmod(e.p, e.q)
coeff *= Pow(b, e_i)
e = Rational(ep, e.q)
num_rat.append((b, e))
del comb_e
# extract gcd of bases in num_rat
# 2**(1/3)*6**(1/4) -> 2**(1/3+1/4)*3**(1/4)
pnew = defaultdict(list)
i = 0 # steps through num_rat which may grow
while i < len(num_rat):
bi, ei = num_rat[i]
grow = []
for j in range(i + 1, len(num_rat)):
bj, ej = num_rat[j]
g = bi.gcd(bj)
if g is not S.One:
# 4**r1*6**r2 -> 2**(r1+r2) * 2**r1 * 3**r2
# this might have a gcd with something else
e = ei + ej
if e.q == 1:
coeff *= Pow(g, e)
else:
if e.p > e.q:
e_i, ep = divmod(e.p, e.q) # change e in place
coeff *= Pow(g, e_i)
e = Rational(ep, e.q)
grow.append((g, e))
# update the jth item
num_rat[j] = (bj/g, ej)
# update bi that we are checking with
bi = bi/g
if bi is S.One:
break
if bi is not S.One:
obj = Pow(bi, ei)
if obj.is_Number:
coeff *= obj
else:
# changes like sqrt(12) -> 2*sqrt(3)
for obj in Mul.make_args(obj):
if obj.is_Number:
coeff *= obj
else:
assert obj.is_Pow
bi, ei = obj.args
pnew[ei].append(bi)
num_rat.extend(grow)
i += 1
# combine bases of the new powers
for e, b in pnew.items():
pnew[e] = cls(*b)
# handle -1 and I
if neg1e:
# treat I as (-1)**(1/2) and compute -1's total exponent
p, q = neg1e.as_numer_denom()
# if the integer part is odd, extract -1
n, p = divmod(p, q)
if n % 2:
coeff = -coeff
# if it's a multiple of 1/2 extract I
if q == 2:
c_part.append(S.ImaginaryUnit)
elif p:
# see if there is any positive base this power of
# -1 can join
neg1e = Rational(p, q)
for e, b in pnew.items():
if e == neg1e and b.is_positive:
pnew[e] = -b
break
else:
# keep it separate; we've already evaluated it as
# much as possible so evaluate=False
c_part.append(Pow(S.NegativeOne, neg1e, evaluate=False))
# add all the pnew powers
c_part.extend([Pow(b, e) for e, b in pnew.items()])
# oo, -oo
if (coeff is S.Infinity) or (coeff is S.NegativeInfinity):
def _handle_for_oo(c_part, coeff_sign):
new_c_part = []
for t in c_part:
if t.is_extended_positive:
continue
if t.is_extended_negative:
coeff_sign *= -1
continue
new_c_part.append(t)
return new_c_part, coeff_sign
c_part, coeff_sign = _handle_for_oo(c_part, 1)
nc_part, coeff_sign = _handle_for_oo(nc_part, coeff_sign)
coeff *= coeff_sign
# zoo
if coeff is S.ComplexInfinity:
# zoo might be
# infinite_real + bounded_im
# bounded_real + infinite_im
# infinite_real + infinite_im
# and non-zero real or imaginary will not change that status.
c_part = [c for c in c_part if not (fuzzy_not(c.is_zero) and
c.is_extended_real is not None)]
nc_part = [c for c in nc_part if not (fuzzy_not(c.is_zero) and
c.is_extended_real is not None)]
# 0
elif coeff.is_zero:
# we know for sure the result will be 0 except the multiplicand
# is infinity or a matrix
if any(isinstance(c, MatrixExpr) for c in nc_part):
return [coeff], nc_part, order_symbols
if any(c.is_finite == False for c in c_part):
return [S.NaN], [], order_symbols
return [coeff], [], order_symbols
# check for straggling Numbers that were produced
_new = []
for i in c_part:
if i.is_Number:
coeff *= i
else:
_new.append(i)
c_part = _new
# order commutative part canonically
_mulsort(c_part)
# current code expects coeff to be always in slot-0
if coeff is not S.One:
c_part.insert(0, coeff)
# we are done
if (global_parameters.distribute and not nc_part and len(c_part) == 2 and
c_part[0].is_Number and c_part[0].is_finite and c_part[1].is_Add):
# 2*(1+a) -> 2 + 2 * a
coeff = c_part[0]
c_part = [Add(*[coeff*f for f in c_part[1].args])]
return c_part, nc_part, order_symbols
def _eval_power(self, e):
# don't break up NC terms: (A*B)**3 != A**3*B**3, it is A*B*A*B*A*B
cargs, nc = self.args_cnc(split_1=False)
if e.is_Integer:
return Mul(*[Pow(b, e, evaluate=False) for b in cargs]) * \
Pow(Mul._from_args(nc), e, evaluate=False)
if e.is_Rational and e.q == 2:
from sympy.core.power import integer_nthroot
from sympy.functions.elementary.complexes import sign
if self.is_imaginary:
a = self.as_real_imag()[1]
if a.is_Rational:
n, d = abs(a/2).as_numer_denom()
n, t = integer_nthroot(n, 2)
if t:
d, t = integer_nthroot(d, 2)
if t:
r = sympify(n)/d
return _unevaluated_Mul(r**e.p, (1 + sign(a)*S.ImaginaryUnit)**e.p)
p = Pow(self, e, evaluate=False)
if e.is_Rational or e.is_Float:
return p._eval_expand_power_base()
return p
@classmethod
def class_key(cls):
return 3, 0, cls.__name__
def _eval_evalf(self, prec):
c, m = self.as_coeff_Mul()
if c is S.NegativeOne:
if m.is_Mul:
rv = -AssocOp._eval_evalf(m, prec)
else:
mnew = m._eval_evalf(prec)
if mnew is not None:
m = mnew
rv = -m
else:
rv = AssocOp._eval_evalf(self, prec)
if rv.is_number:
return rv.expand()
return rv
@property
def _mpc_(self):
"""
Convert self to an mpmath mpc if possible
"""
from sympy.core.numbers import I, Float
im_part, imag_unit = self.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 Mul to mpc. Must be of the form Number*I")
return (Float(0)._mpf_, Float(im_part)._mpf_)
@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_mul() which gives the head and a tuple containing
the arguments of the tail when treated as a Mul.
- if you want the coefficient when self is treated as an Add
then use self.as_coeff_add()[0]
Examples
========
>>> from sympy.abc import x, y
>>> (3*x*y).as_two_terms()
(3, x*y)
"""
args = self.args
if len(args) == 1:
return S.One, self
elif len(args) == 2:
return args
else:
return args[0], self._new_rawargs(*args[1:])
@cacheit
def as_coefficients_dict(self):
"""Return a dictionary mapping terms to their coefficient.
Since the dictionary is a defaultdict, inquiries about terms which
were not present will return a coefficient of 0. The dictionary
is considered to have a single term.
Examples
========
>>> from sympy.abc import a, x
>>> (3*a*x).as_coefficients_dict()
{a*x: 3}
>>> _[a]
0
"""
d = defaultdict(int)
args = self.args
if len(args) == 1 or not args[0].is_Number:
d[self] = S.One
else:
d[self._new_rawargs(*args[1:])] = args[0]
return d
@cacheit
def as_coeff_mul(self, *deps, rational=True, **kwargs):
if deps:
from sympy.utilities.iterables import sift
l1, l2 = sift(self.args, lambda x: x.has(*deps), binary=True)
return self._new_rawargs(*l2), tuple(l1)
args = self.args
if args[0].is_Number:
if not rational or args[0].is_Rational:
return args[0], args[1:]
elif args[0].is_extended_negative:
return S.NegativeOne, (-args[0],) + args[1:]
return S.One, args
def as_coeff_Mul(self, rational=False):
"""
Efficiently extract the coefficient of a product.
"""
coeff, args = self.args[0], self.args[1:]
if coeff.is_Number:
if not rational or coeff.is_Rational:
if len(args) == 1:
return coeff, args[0]
else:
return coeff, self._new_rawargs(*args)
elif coeff.is_extended_negative:
return S.NegativeOne, self._new_rawargs(*((-coeff,) + args))
return S.One, self
def as_real_imag(self, deep=True, **hints):
from sympy import Abs, expand_mul, im, re
other = []
coeffr = []
coeffi = []
addterms = S.One
for a in self.args:
r, i = a.as_real_imag()
if i.is_zero:
coeffr.append(r)
elif r.is_zero:
coeffi.append(i*S.ImaginaryUnit)
elif a.is_commutative:
# search for complex conjugate pairs:
for i, x in enumerate(other):
if x == a.conjugate():
coeffr.append(Abs(x)**2)
del other[i]
break
else:
if a.is_Add:
addterms *= a
else:
other.append(a)
else:
other.append(a)
m = self.func(*other)
if hints.get('ignore') == m:
return
if len(coeffi) % 2:
imco = im(coeffi.pop(0))
# all other pairs make a real factor; they will be
# put into reco below
else:
imco = S.Zero
reco = self.func(*(coeffr + coeffi))
r, i = (reco*re(m), reco*im(m))
if addterms == 1:
if m == 1:
if imco.is_zero:
return (reco, S.Zero)
else:
return (S.Zero, reco*imco)
if imco is S.Zero:
return (r, i)
return (-imco*i, imco*r)
addre, addim = expand_mul(addterms, deep=False).as_real_imag()
if imco is S.Zero:
return (r*addre - i*addim, i*addre + r*addim)
else:
r, i = -imco*i, imco*r
return (r*addre - i*addim, r*addim + i*addre)
@staticmethod
def _expandsums(sums):
"""
Helper function for _eval_expand_mul.
sums must be a list of instances of Basic.
"""
L = len(sums)
if L == 1:
return sums[0].args
terms = []
left = Mul._expandsums(sums[:L//2])
right = Mul._expandsums(sums[L//2:])
terms = [Mul(a, b) for a in left for b in right]
added = Add(*terms)
return Add.make_args(added) # it may have collapsed down to one term
def _eval_expand_mul(self, **hints):
from sympy import fraction
# Handle things like 1/(x*(x + 1)), which are automatically converted
# to 1/x*1/(x + 1)
expr = self
n, d = fraction(expr)
if d.is_Mul:
n, d = [i._eval_expand_mul(**hints) if i.is_Mul else i
for i in (n, d)]
expr = n/d
if not expr.is_Mul:
return expr
plain, sums, rewrite = [], [], False
for factor in expr.args:
if factor.is_Add:
sums.append(factor)
rewrite = True
else:
if factor.is_commutative:
plain.append(factor)
else:
sums.append(Basic(factor)) # Wrapper
if not rewrite:
return expr
else:
plain = self.func(*plain)
if sums:
deep = hints.get("deep", False)
terms = self.func._expandsums(sums)
args = []
for term in terms:
t = self.func(plain, term)
if t.is_Mul and any(a.is_Add for a in t.args) and deep:
t = t._eval_expand_mul()
args.append(t)
return Add(*args)
else:
return plain
@cacheit
def _eval_derivative(self, s):
args = list(self.args)
terms = []
for i in range(len(args)):
d = args[i].diff(s)
if d:
# Note: reduce is used in step of Mul as Mul is unable to
# handle subtypes and operation priority:
terms.append(reduce(lambda x, y: x*y, (args[:i] + [d] + args[i + 1:]), S.One))
return Add.fromiter(terms)
@cacheit
def _eval_derivative_n_times(self, s, n):
from sympy import Integer, factorial, prod, Sum, Max
from sympy.ntheory.multinomial import multinomial_coefficients_iterator
from .function import AppliedUndef
from .symbol import Symbol, symbols, Dummy
if not isinstance(s, AppliedUndef) and not isinstance(s, Symbol):
# other types of s may not be well behaved, e.g.
# (cos(x)*sin(y)).diff([[x, y, z]])
return super()._eval_derivative_n_times(s, n)
args = self.args
m = len(args)
if isinstance(n, (int, Integer)):
# https://en.wikipedia.org/wiki/General_Leibniz_rule#More_than_two_factors
terms = []
for kvals, c in multinomial_coefficients_iterator(m, n):
p = prod([arg.diff((s, k)) for k, arg in zip(kvals, args)])
terms.append(c * p)
return Add(*terms)
kvals = symbols("k1:%i" % m, cls=Dummy)
klast = n - sum(kvals)
nfact = factorial(n)
e, l = (# better to use the multinomial?
nfact/prod(map(factorial, kvals))/factorial(klast)*\
prod([args[t].diff((s, kvals[t])) for t in range(m-1)])*\
args[-1].diff((s, Max(0, klast))),
[(k, 0, n) for k in kvals])
return Sum(e, *l)
def _eval_difference_delta(self, n, step):
from sympy.series.limitseq import difference_delta as dd
arg0 = self.args[0]
rest = Mul(*self.args[1:])
return (arg0.subs(n, n + step) * dd(rest, n, step) + dd(arg0, n, step) *
rest)
def _matches_simple(self, expr, repl_dict):
# handle (w*3).matches('x*5') -> {w: x*5/3}
coeff, terms = self.as_coeff_Mul()
terms = Mul.make_args(terms)
if len(terms) == 1:
newexpr = self.__class__._combine_inverse(expr, coeff)
return terms[0].matches(newexpr, repl_dict)
return
def matches(self, expr, repl_dict={}, old=False):
expr = sympify(expr)
repl_dict = repl_dict.copy()
if self.is_commutative and expr.is_commutative:
return self._matches_commutative(expr, repl_dict, old)
elif self.is_commutative is not expr.is_commutative:
return None
# Proceed only if both both expressions are non-commutative
c1, nc1 = self.args_cnc()
c2, nc2 = expr.args_cnc()
c1, c2 = [c or [1] for c in [c1, c2]]
# TODO: Should these be self.func?
comm_mul_self = Mul(*c1)
comm_mul_expr = Mul(*c2)
repl_dict = comm_mul_self.matches(comm_mul_expr, repl_dict, old)
# If the commutative arguments didn't match and aren't equal, then
# then the expression as a whole doesn't match
if repl_dict is None and c1 != c2:
return None
# Now match the non-commutative arguments, expanding powers to
# multiplications
nc1 = Mul._matches_expand_pows(nc1)
nc2 = Mul._matches_expand_pows(nc2)
repl_dict = Mul._matches_noncomm(nc1, nc2, repl_dict)
return repl_dict or None
@staticmethod
def _matches_expand_pows(arg_list):
new_args = []
for arg in arg_list:
if arg.is_Pow and arg.exp > 0:
new_args.extend([arg.base] * arg.exp)
else:
new_args.append(arg)
return new_args
@staticmethod
def _matches_noncomm(nodes, targets, repl_dict={}):
"""Non-commutative multiplication matcher.
`nodes` is a list of symbols within the matcher multiplication
expression, while `targets` is a list of arguments in the
multiplication expression being matched against.
"""
repl_dict = repl_dict.copy()
# List of possible future states to be considered
agenda = []
# The current matching state, storing index in nodes and targets
state = (0, 0)
node_ind, target_ind = state
# Mapping between wildcard indices and the index ranges they match
wildcard_dict = {}
repl_dict = repl_dict.copy()
while target_ind < len(targets) and node_ind < len(nodes):
node = nodes[node_ind]
if node.is_Wild:
Mul._matches_add_wildcard(wildcard_dict, state)
states_matches = Mul._matches_new_states(wildcard_dict, state,
nodes, targets)
if states_matches:
new_states, new_matches = states_matches
agenda.extend(new_states)
if new_matches:
for match in new_matches:
repl_dict[match] = new_matches[match]
if not agenda:
return None
else:
state = agenda.pop()
node_ind, target_ind = state
return repl_dict
@staticmethod
def _matches_add_wildcard(dictionary, state):
node_ind, target_ind = state
if node_ind in dictionary:
begin, end = dictionary[node_ind]
dictionary[node_ind] = (begin, target_ind)
else:
dictionary[node_ind] = (target_ind, target_ind)
@staticmethod
def _matches_new_states(dictionary, state, nodes, targets):
node_ind, target_ind = state
node = nodes[node_ind]
target = targets[target_ind]
# Don't advance at all if we've exhausted the targets but not the nodes
if target_ind >= len(targets) - 1 and node_ind < len(nodes) - 1:
return None
if node.is_Wild:
match_attempt = Mul._matches_match_wilds(dictionary, node_ind,
nodes, targets)
if match_attempt:
# If the same node has been matched before, don't return
# anything if the current match is diverging from the previous
# match
other_node_inds = Mul._matches_get_other_nodes(dictionary,
nodes, node_ind)
for ind in other_node_inds:
other_begin, other_end = dictionary[ind]
curr_begin, curr_end = dictionary[node_ind]
other_targets = targets[other_begin:other_end + 1]
current_targets = targets[curr_begin:curr_end + 1]
for curr, other in zip(current_targets, other_targets):
if curr != other:
return None
# A wildcard node can match more than one target, so only the
# target index is advanced
new_state = [(node_ind, target_ind + 1)]
# Only move on to the next node if there is one
if node_ind < len(nodes) - 1:
new_state.append((node_ind + 1, target_ind + 1))
return new_state, match_attempt
else:
# If we're not at a wildcard, then make sure we haven't exhausted
# nodes but not targets, since in this case one node can only match
# one target
if node_ind >= len(nodes) - 1 and target_ind < len(targets) - 1:
return None
match_attempt = node.matches(target)
if match_attempt:
return [(node_ind + 1, target_ind + 1)], match_attempt
elif node == target:
return [(node_ind + 1, target_ind + 1)], None
else:
return None
@staticmethod
def _matches_match_wilds(dictionary, wildcard_ind, nodes, targets):
"""Determine matches of a wildcard with sub-expression in `target`."""
wildcard = nodes[wildcard_ind]
begin, end = dictionary[wildcard_ind]
terms = targets[begin:end + 1]
# TODO: Should this be self.func?
mul = Mul(*terms) if len(terms) > 1 else terms[0]
return wildcard.matches(mul)
@staticmethod
def _matches_get_other_nodes(dictionary, nodes, node_ind):
"""Find other wildcards that may have already been matched."""
other_node_inds = []
for ind in dictionary:
if nodes[ind] == nodes[node_ind]:
other_node_inds.append(ind)
return other_node_inds
@staticmethod
def _combine_inverse(lhs, rhs):
"""
Returns lhs/rhs, but treats arguments like symbols, so things
like oo/oo return 1 (instead of a nan) and ``I`` behaves like
a symbol instead of sqrt(-1).
"""
from sympy.simplify.simplify import signsimp
from .symbol import Dummy
if lhs == rhs:
return S.One
def check(l, r):
if l.is_Float and r.is_comparable:
# if both objects are added to 0 they will share the same "normalization"
# and are more likely to compare the same. Since Add(foo, 0) will not allow
# the 0 to pass, we use __add__ directly.
return l.__add__(0) == r.evalf().__add__(0)
return False
if check(lhs, rhs) or check(rhs, lhs):
return S.One
if any(i.is_Pow or i.is_Mul for i in (lhs, rhs)):
# gruntz and limit wants a literal I to not combine
# with a power of -1
d = Dummy('I')
_i = {S.ImaginaryUnit: d}
i_ = {d: S.ImaginaryUnit}
a = lhs.xreplace(_i).as_powers_dict()
b = rhs.xreplace(_i).as_powers_dict()
blen = len(b)
for bi in tuple(b.keys()):
if bi in a:
a[bi] -= b.pop(bi)
if not a[bi]:
a.pop(bi)
if len(b) != blen:
lhs = Mul(*[k**v for k, v in a.items()]).xreplace(i_)
rhs = Mul(*[k**v for k, v in b.items()]).xreplace(i_)
return signsimp(lhs/rhs)
def as_powers_dict(self):
d = defaultdict(int)
for term in self.args:
for b, e in term.as_powers_dict().items():
d[b] += e
return d
def as_numer_denom(self):
# don't use _from_args to rebuild the numerators and denominators
# as the order is not guaranteed to be the same once they have
# been separated from each other
numers, denoms = list(zip(*[f.as_numer_denom() for f in self.args]))
return self.func(*numers), self.func(*denoms)
def as_base_exp(self):
e1 = None
bases = []
nc = 0
for m in self.args:
b, e = m.as_base_exp()
if not b.is_commutative:
nc += 1
if e1 is None:
e1 = e
elif e != e1 or nc > 1:
return self, S.One
bases.append(b)
return self.func(*bases), e1
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_meromorphic(self, x, a):
return _fuzzy_group((arg.is_meromorphic(x, a) for arg in self.args),
quick_exit=True)
def _eval_is_algebraic_expr(self, syms):
return all(term._eval_is_algebraic_expr(syms) for term in self.args)
_eval_is_commutative = lambda self: _fuzzy_group(
a.is_commutative for a in self.args)
def _eval_is_complex(self):
comp = _fuzzy_group(a.is_complex for a in self.args)
if comp is False:
if any(a.is_infinite for a in self.args):
if any(a.is_zero is not False for a in self.args):
return None
return False
return comp
def _eval_is_finite(self):
if all(a.is_finite for a in self.args):
return True
if any(a.is_infinite for a in self.args):
if all(a.is_zero is False for a in self.args):
return False
def _eval_is_infinite(self):
if any(a.is_infinite for a in self.args):
if any(a.is_zero for a in self.args):
return S.NaN.is_infinite
if any(a.is_zero is None for a in self.args):
return None
return True
def _eval_is_rational(self):
r = _fuzzy_group((a.is_rational for a in self.args), quick_exit=True)
if r:
return r
elif r is False:
return self.is_zero
def _eval_is_algebraic(self):
r = _fuzzy_group((a.is_algebraic for a in self.args), quick_exit=True)
if r:
return r
elif r is False:
return self.is_zero
def _eval_is_zero(self):
zero = infinite = False
for a in self.args:
z = a.is_zero
if z:
if infinite:
return # 0*oo is nan and nan.is_zero is None
zero = True
else:
if not a.is_finite:
if zero:
return # 0*oo is nan and nan.is_zero is None
infinite = True
if zero is False and z is None: # trap None
zero = None
return zero
# without involving odd/even checks this code would suffice:
#_eval_is_integer = lambda self: _fuzzy_group(
# (a.is_integer for a in self.args), quick_exit=True)
def _eval_is_integer(self):
is_rational = self._eval_is_rational()
if is_rational is False:
return False
numerators = []
denominators = []
for a in self.args:
if a.is_integer:
numerators.append(a)
elif a.is_Rational:
n, d = a.as_numer_denom()
numerators.append(n)
denominators.append(d)
elif a.is_Pow:
b, e = a.as_base_exp()
if not b.is_integer or not e.is_integer: return
if e.is_negative:
denominators.append(b)
else:
# for integer b and positive integer e: a = b**e would be integer
assert not e.is_positive
# for self being rational and e equal to zero: a = b**e would be 1
assert not e.is_zero
return # sign of e unknown -> self.is_integer cannot be decided
else:
return
if not denominators:
return True
odd = lambda ints: all(i.is_odd for i in ints)
even = lambda ints: any(i.is_even for i in ints)
if odd(numerators) and even(denominators):
return False
elif even(numerators) and denominators == [2]:
return True
def _eval_is_polar(self):
has_polar = any(arg.is_polar for arg in self.args)
return has_polar and \
all(arg.is_polar or arg.is_positive for arg in self.args)
def _eval_is_extended_real(self):
return self._eval_real_imag(True)
def _eval_real_imag(self, real):
zero = False
t_not_re_im = None
for t in self.args:
if (t.is_complex or t.is_infinite) is False and t.is_extended_real is False:
return False
elif t.is_imaginary: # I
real = not real
elif t.is_extended_real: # 2
if not zero:
z = t.is_zero
if not z and zero is False:
zero = z
elif z:
if all(a.is_finite for a in self.args):
return True
return
elif t.is_extended_real is False:
# symbolic or literal like `2 + I` or symbolic imaginary
if t_not_re_im:
return # complex terms might cancel
t_not_re_im = t
elif t.is_imaginary is False: # symbolic like `2` or `2 + I`
if t_not_re_im:
return # complex terms might cancel
t_not_re_im = t
else:
return
if t_not_re_im:
if t_not_re_im.is_extended_real is False:
if real: # like 3
return zero # 3*(smthng like 2 + I or i) is not real
if t_not_re_im.is_imaginary is False: # symbolic 2 or 2 + I
if not real: # like I
return zero # I*(smthng like 2 or 2 + I) is not real
elif zero is False:
return real # can't be trumped by 0
elif real:
return real # doesn't matter what zero is
def _eval_is_imaginary(self):
z = self.is_zero
if z:
return False
if self.is_finite is False:
return False
elif z is False and self.is_finite is True:
return self._eval_real_imag(False)
def _eval_is_hermitian(self):
return self._eval_herm_antiherm(True)
def _eval_herm_antiherm(self, real):
one_nc = zero = one_neither = False
for t in self.args:
if not t.is_commutative:
if one_nc:
return
one_nc = True
if t.is_antihermitian:
real = not real
elif t.is_hermitian:
if not zero:
z = t.is_zero
if not z and zero is False:
zero = z
elif z:
if all(a.is_finite for a in self.args):
return True
return
elif t.is_hermitian is False:
if one_neither:
return
one_neither = True
else:
return
if one_neither:
if real:
return zero
elif zero is False or real:
return real
def _eval_is_antihermitian(self):
z = self.is_zero
if z:
return False
elif z is False:
return self._eval_herm_antiherm(False)
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 and fuzzy_not(x.is_zero)) is True for x in others):
return True
return
if a is None:
return
if all(x.is_real for x in self.args):
return False
def _eval_is_extended_positive(self):
"""Return True if self is positive, False if not, and None if it
cannot be determined.
Explanation
===========
This algorithm is non-recursive and works by keeping track of the
sign which changes when a negative or nonpositive is encountered.
Whether a nonpositive or nonnegative is seen is also tracked since
the presence of these makes it impossible to return True, but
possible to return False if the end result is nonpositive. e.g.
pos * neg * nonpositive -> pos or zero -> None is returned
pos * neg * nonnegative -> neg or zero -> False is returned
"""
return self._eval_pos_neg(1)
def _eval_pos_neg(self, sign):
saw_NON = saw_NOT = False
for t in self.args:
if t.is_extended_positive:
continue
elif t.is_extended_negative:
sign = -sign
elif t.is_zero:
if all(a.is_finite for a in self.args):
return False
return
elif t.is_extended_nonpositive:
sign = -sign
saw_NON = True
elif t.is_extended_nonnegative:
saw_NON = True
# FIXME: is_positive/is_negative is False doesn't take account of
# Symbol('x', infinite=True, extended_real=True) which has
# e.g. is_positive is False but has uncertain sign.
elif t.is_positive is False:
sign = -sign
if saw_NOT:
return
saw_NOT = True
elif t.is_negative is False:
if saw_NOT:
return
saw_NOT = True
else:
return
if sign == 1 and saw_NON is False and saw_NOT is False:
return True
if sign < 0:
return False
def _eval_is_extended_negative(self):
return self._eval_pos_neg(-1)
def _eval_is_odd(self):
is_integer = self.is_integer
if is_integer:
r, acc = True, 1
for t in self.args:
if not t.is_integer:
return None
elif t.is_even:
r = False
elif t.is_integer:
if r is False:
pass
elif acc != 1 and (acc + t).is_odd:
r = False
elif t.is_odd is None:
r = None
acc = t
return r
# !integer -> !odd
elif is_integer is False:
return False
def _eval_is_even(self):
is_integer = self.is_integer
if is_integer:
return fuzzy_not(self.is_odd)
elif is_integer is False:
return False
def _eval_is_composite(self):
"""
Here we count the number of arguments that have a minimum value
greater than two.
If there are more than one of such a symbol then the result is composite.
Else, the result cannot be determined.
"""
number_of_args = 0 # count of symbols with minimum value greater than one
for arg in self.args:
if not (arg.is_integer and arg.is_positive):
return None
if (arg-1).is_positive:
number_of_args += 1
if number_of_args > 1:
return True
def _eval_subs(self, old, new):
from sympy.functions.elementary.complexes import sign
from sympy.ntheory.factor_ import multiplicity
from sympy.simplify.powsimp import powdenest
from sympy.simplify.radsimp import fraction
if not old.is_Mul:
return None
# try keep replacement literal so -2*x doesn't replace 4*x
if old.args[0].is_Number and old.args[0] < 0:
if self.args[0].is_Number:
if self.args[0] < 0:
return self._subs(-old, -new)
return None
def base_exp(a):
# if I and -1 are in a Mul, they get both end up with
# a -1 base (see issue 6421); all we want here are the
# true Pow or exp separated into base and exponent
from sympy import exp
if a.is_Pow or isinstance(a, exp):
return a.as_base_exp()
return a, S.One
def breakup(eq):
"""break up powers of eq when treated as a Mul:
b**(Rational*e) -> b**e, Rational
commutatives come back as a dictionary {b**e: Rational}
noncommutatives come back as a list [(b**e, Rational)]
"""
(c, nc) = (defaultdict(int), list())
for a in Mul.make_args(eq):
a = powdenest(a)
(b, e) = base_exp(a)
if e is not S.One:
(co, _) = e.as_coeff_mul()
b = Pow(b, e/co)
e = co
if a.is_commutative:
c[b] += e
else:
nc.append([b, e])
return (c, nc)
def rejoin(b, co):
"""
Put rational back with exponent; in general this is not ok, but
since we took it from the exponent for analysis, it's ok to put
it back.
"""
(b, e) = base_exp(b)
return Pow(b, e*co)
def ndiv(a, b):
"""if b divides a in an extractive way (like 1/4 divides 1/2
but not vice versa, and 2/5 does not divide 1/3) then return
the integer number of times it divides, else return 0.
"""
if not b.q % a.q or not a.q % b.q:
return int(a/b)
return 0
# give Muls in the denominator a chance to be changed (see issue 5651)
# rv will be the default return value
rv = None
n, d = fraction(self)
self2 = self
if d is not S.One:
self2 = n._subs(old, new)/d._subs(old, new)
if not self2.is_Mul:
return self2._subs(old, new)
if self2 != self:
rv = self2
# Now continue with regular substitution.
# handle the leading coefficient and use it to decide if anything
# should even be started; we always know where to find the Rational
# so it's a quick test
co_self = self2.args[0]
co_old = old.args[0]
co_xmul = None
if co_old.is_Rational and co_self.is_Rational:
# if coeffs are the same there will be no updating to do
# below after breakup() step; so skip (and keep co_xmul=None)
if co_old != co_self:
co_xmul = co_self.extract_multiplicatively(co_old)
elif co_old.is_Rational:
return rv
# break self and old into factors
(c, nc) = breakup(self2)
(old_c, old_nc) = breakup(old)
# update the coefficients if we had an extraction
# e.g. if co_self were 2*(3/35*x)**2 and co_old = 3/5
# then co_self in c is replaced by (3/5)**2 and co_residual
# is 2*(1/7)**2
if co_xmul and co_xmul.is_Rational and abs(co_old) != 1:
mult = S(multiplicity(abs(co_old), co_self))
c.pop(co_self)
if co_old in c:
c[co_old] += mult
else:
c[co_old] = mult
co_residual = co_self/co_old**mult
else:
co_residual = 1
# do quick tests to see if we can't succeed
ok = True
if len(old_nc) > len(nc):
# more non-commutative terms
ok = False
elif len(old_c) > len(c):
# more commutative terms
ok = False
elif {i[0] for i in old_nc}.difference({i[0] for i in nc}):
# unmatched non-commutative bases
ok = False
elif set(old_c).difference(set(c)):
# unmatched commutative terms
ok = False
elif any(sign(c[b]) != sign(old_c[b]) for b in old_c):
# differences in sign
ok = False
if not ok:
return rv
if not old_c:
cdid = None
else:
rat = []
for (b, old_e) in old_c.items():
c_e = c[b]
rat.append(ndiv(c_e, old_e))
if not rat[-1]:
return rv
cdid = min(rat)
if not old_nc:
ncdid = None
for i in range(len(nc)):
nc[i] = rejoin(*nc[i])
else:
ncdid = 0 # number of nc replacements we did
take = len(old_nc) # how much to look at each time
limit = cdid or S.Infinity # max number that we can take
failed = [] # failed terms will need subs if other terms pass
i = 0
while limit and i + take <= len(nc):
hit = False
# the bases must be equivalent in succession, and
# the powers must be extractively compatible on the
# first and last factor but equal in between.
rat = []
for j in range(take):
if nc[i + j][0] != old_nc[j][0]:
break
elif j == 0:
rat.append(ndiv(nc[i + j][1], old_nc[j][1]))
elif j == take - 1:
rat.append(ndiv(nc[i + j][1], old_nc[j][1]))
elif nc[i + j][1] != old_nc[j][1]:
break
else:
rat.append(1)
j += 1
else:
ndo = min(rat)
if ndo:
if take == 1:
if cdid:
ndo = min(cdid, ndo)
nc[i] = Pow(new, ndo)*rejoin(nc[i][0],
nc[i][1] - ndo*old_nc[0][1])
else:
ndo = 1
# the left residual
l = rejoin(nc[i][0], nc[i][1] - ndo*
old_nc[0][1])
# eliminate all middle terms
mid = new
# the right residual (which may be the same as the middle if take == 2)
ir = i + take - 1
r = (nc[ir][0], nc[ir][1] - ndo*
old_nc[-1][1])
if r[1]:
if i + take < len(nc):
nc[i:i + take] = [l*mid, r]
else:
r = rejoin(*r)
nc[i:i + take] = [l*mid*r]
else:
# there was nothing left on the right
nc[i:i + take] = [l*mid]
limit -= ndo
ncdid += ndo
hit = True
if not hit:
# do the subs on this failing factor
failed.append(i)
i += 1
else:
if not ncdid:
return rv
# although we didn't fail, certain nc terms may have
# failed so we rebuild them after attempting a partial
# subs on them
failed.extend(range(i, len(nc)))
for i in failed:
nc[i] = rejoin(*nc[i]).subs(old, new)
# rebuild the expression
if cdid is None:
do = ncdid
elif ncdid is None:
do = cdid
else:
do = min(ncdid, cdid)
margs = []
for b in c:
if b in old_c:
# calculate the new exponent
e = c[b] - old_c[b]*do
margs.append(rejoin(b, e))
else:
margs.append(rejoin(b.subs(old, new), c[b]))
if cdid and not ncdid:
# in case we are replacing commutative with non-commutative,
# we want the new term to come at the front just like the
# rest of this routine
margs = [Pow(new, cdid)] + margs
return co_residual*self2.func(*margs)*self2.func(*nc)
def _eval_nseries(self, x, n, logx, cdir=0):
from sympy import degree, Mul, Order, ceiling, powsimp, PolynomialError, PoleError
from itertools import product
def coeff_exp(term, x):
lt = term.as_coeff_exponent(x)
if lt[0].has(x):
try:
lt = term.leadterm(x)
except ValueError:
return term, S.Zero
return lt
ords = []
try:
for t in self.args:
coeff, exp = t.leadterm(x, logx=logx)
if not coeff.has(x):
ords.append((t, exp))
else:
raise ValueError
n0 = sum(t[1] for t in ords if t[1].is_number)
facs = []
for t, m in ords:
n1 = ceiling(n - n0 + (m if m.is_number else 0))
s = t.nseries(x, n=n1, logx=logx, cdir=cdir)
ns = s.getn()
if ns is not None:
if ns < n1: # less than expected
n -= n1 - ns # reduce n
facs.append(s)
except (ValueError, NotImplementedError, TypeError, AttributeError, PoleError):
n0 = sympify(sum(t[1] for t in ords if t[1].is_number))
if n0.is_nonnegative:
n0 = S.Zero
facs = [t.nseries(x, n=ceiling(n-n0), logx=logx, cdir=cdir) for t in self.args]
res = powsimp(self.func(*facs).expand(), combine='exp', deep=True)
if res.has(Order):
res += Order(x**n, x)
return res
res = S.Zero
ords2 = [Add.make_args(factor) for factor in facs]
for fac in product(*ords2):
ords3 = [coeff_exp(term, x) for term in fac]
coeffs, powers = zip(*ords3)
power = sum(powers)
if (power - n).is_negative:
res += Mul(*coeffs)*(x**power)
def max_degree(e, x):
if e is x:
return S.One
if e.is_Atom:
return S.Zero
if e.is_Add:
return max(max_degree(a, x) for a in e.args)
if e.is_Mul:
return Add(*[max_degree(a, x) for a in e.args])
if e.is_Pow:
return max_degree(e.base, x)*e.exp
return S.Zero
if self.is_polynomial(x):
try:
if max_degree(self, x) >= n or degree(self, x) != degree(res, x):
res += Order(x**n, x)
except PolynomialError:
pass
else:
return res
if res != self:
res += Order(x**n, x)
return res
def _eval_as_leading_term(self, x, logx=None, cdir=0):
return self.func(*[t.as_leading_term(x, logx=logx, cdir=cdir) 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[::-1]])
def _eval_adjoint(self):
return self.func(*[t.adjoint() for t in self.args[::-1]])
def _sage_(self):
s = 1
for x in self.args:
s *= x._sage_()
return s
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 sqrt
>>> (-3*sqrt(2)*(2 - 2*sqrt(2))).as_content_primitive()
(6, -sqrt(2)*(1 - sqrt(2)))
See docstring of Expr.as_content_primitive for more examples.
"""
coef = S.One
args = []
for i, a in enumerate(self.args):
c, p = a.as_content_primitive(radical=radical, clear=clear)
coef *= c
if p is not S.One:
args.append(p)
# don't use self._from_args here to reconstruct args
# since there may be identical args now that should be combined
# e.g. (2+2*x)*(3+3*x) should be (6, (1 + x)**2) not (6, (1+x)*(1+x))
return coef, self.func(*args)
def as_ordered_factors(self, order=None):
"""Transform an expression into an ordered list of factors.
Examples
========
>>> from sympy import sin, cos
>>> from sympy.abc import x, y
>>> (2*x*y*sin(x)*cos(x)).as_ordered_factors()
[2, x, y, sin(x), cos(x)]
"""
cpart, ncpart = self.args_cnc()
cpart.sort(key=lambda expr: expr.sort_key(order=order))
return cpart + ncpart
@property
def _sorted_args(self):
return tuple(self.as_ordered_factors())
mul = AssocOpDispatcher('mul')
def prod(a, start=1):
"""Return product of elements of a. Start with int 1 so if only
ints are included then an int result is returned.
Examples
========
>>> from sympy import prod, S
>>> prod(range(3))
0
>>> type(_) is int
True
>>> prod([S(2), 3])
6
>>> _.is_Integer
True
You can start the product at something other than 1:
>>> prod([1, 2], 3)
6
"""
return reduce(operator.mul, a, start)
def _keep_coeff(coeff, factors, clear=True, sign=False):
"""Return ``coeff*factors`` unevaluated if necessary.
If ``clear`` is False, do not keep the coefficient as a factor
if it can be distributed on a single factor such that one or
more terms will still have integer coefficients.
If ``sign`` is True, allow a coefficient of -1 to remain factored out.
Examples
========
>>> from sympy.core.mul import _keep_coeff
>>> from sympy.abc import x, y
>>> from sympy import S
>>> _keep_coeff(S.Half, x + 2)
(x + 2)/2
>>> _keep_coeff(S.Half, x + 2, clear=False)
x/2 + 1
>>> _keep_coeff(S.Half, (x + 2)*y, clear=False)
y*(x + 2)/2
>>> _keep_coeff(S(-1), x + y)
-x - y
>>> _keep_coeff(S(-1), x + y, sign=True)
-(x + y)
"""
if not coeff.is_Number:
if factors.is_Number:
factors, coeff = coeff, factors
else:
return coeff*factors
if factors is S.One:
return coeff
if coeff is S.One:
return factors
elif coeff is S.NegativeOne and not sign:
return -factors
elif factors.is_Add:
if not clear and coeff.is_Rational and coeff.q != 1:
args = [i.as_coeff_Mul() for i in factors.args]
args = [(_keep_coeff(c, coeff), m) for c, m in args]
if any(c == int(c) for c, _ in args):
return Add._from_args([Mul._from_args(
i[1:] if i[0] == 1 else i) for i in args])
return Mul(coeff, factors, evaluate=False)
elif factors.is_Mul:
margs = list(factors.args)
if margs[0].is_Number:
margs[0] *= coeff
if margs[0] == 1:
margs.pop(0)
else:
margs.insert(0, coeff)
return Mul._from_args(margs)
else:
m = coeff*factors
if m.is_Number and not factors.is_Number:
m = Mul._from_args((coeff, factors))
return m
def expand_2arg(e):
from sympy.simplify.simplify import bottom_up
def do(e):
if e.is_Mul:
c, r = e.as_coeff_Mul()
if c.is_Number and r.is_Add:
return _unevaluated_Add(*[c*ri for ri in r.args])
return e
return bottom_up(e, do)
from .numbers import Rational
from .power import Pow
from .add import Add, _addsort, _unevaluated_Add
|
6661d9efdba9deb57d86e5d46a973b8304e844445f6d43d957faa666669ed193 | """Tools for setting up interactive sessions. """
from distutils.version import LooseVersion as V
from sympy.interactive.printing import init_printing
preexec_source = """\
from __future__ import division
from sympy import *
x, y, z, t = symbols('x y z t')
k, m, n = symbols('k m n', integer=True)
f, g, h = symbols('f g h', cls=Function)
init_printing()
"""
verbose_message = """\
These commands were executed:
%(source)s
Documentation can be found at https://docs.sympy.org/%(version)s
"""
no_ipython = """\
Couldn't locate IPython. Having IPython installed is greatly recommended.
See http://ipython.scipy.org for more details. If you use Debian/Ubuntu,
just install the 'ipython' package and start isympy again.
"""
def _make_message(ipython=True, quiet=False, source=None):
"""Create a banner for an interactive session. """
from sympy import __version__ as sympy_version
from sympy.external.gmpy import GROUND_TYPES
from sympy.utilities.misc import ARCH
from sympy import SYMPY_DEBUG
import sys
import os
if quiet:
return ""
python_version = "%d.%d.%d" % sys.version_info[:3]
if ipython:
shell_name = "IPython"
else:
shell_name = "Python"
info = ['ground types: %s' % GROUND_TYPES]
cache = os.getenv('SYMPY_USE_CACHE')
if cache is not None and cache.lower() == 'no':
info.append('cache: off')
if SYMPY_DEBUG:
info.append('debugging: on')
args = shell_name, sympy_version, python_version, ARCH, ', '.join(info)
message = "%s console for SymPy %s (Python %s-%s) (%s)\n" % args
if source is None:
source = preexec_source
_source = ""
for line in source.split('\n')[:-1]:
if not line:
_source += '\n'
else:
_source += '>>> ' + line + '\n'
doc_version = sympy_version
if 'dev' in doc_version:
doc_version = "dev"
else:
doc_version = "%s/" % doc_version
message += '\n' + verbose_message % {'source': _source,
'version': doc_version}
return message
def int_to_Integer(s):
"""
Wrap integer literals with Integer.
This is based on the decistmt example from
http://docs.python.org/library/tokenize.html.
Only integer literals are converted. Float literals are left alone.
Examples
========
>>> from __future__ import division
>>> from sympy import Integer # noqa: F401
>>> from sympy.interactive.session import int_to_Integer
>>> s = '1.2 + 1/2 - 0x12 + a1'
>>> int_to_Integer(s)
'1.2 +Integer (1 )/Integer (2 )-Integer (0x12 )+a1 '
>>> s = 'print (1/2)'
>>> int_to_Integer(s)
'print (Integer (1 )/Integer (2 ))'
>>> exec(s)
0.5
>>> exec(int_to_Integer(s))
1/2
"""
from tokenize import generate_tokens, untokenize, NUMBER, NAME, OP
from io import StringIO
def _is_int(num):
"""
Returns true if string value num (with token NUMBER) represents an integer.
"""
# XXX: Is there something in the standard library that will do this?
if '.' in num or 'j' in num.lower() or 'e' in num.lower():
return False
return True
result = []
g = generate_tokens(StringIO(s).readline) # tokenize the string
for toknum, tokval, _, _, _ in g:
if toknum == NUMBER and _is_int(tokval): # replace NUMBER tokens
result.extend([
(NAME, 'Integer'),
(OP, '('),
(NUMBER, tokval),
(OP, ')')
])
else:
result.append((toknum, tokval))
return untokenize(result)
def enable_automatic_int_sympification(shell):
"""
Allow IPython to automatically convert integer literals to Integer.
"""
import ast
old_run_cell = shell.run_cell
def my_run_cell(cell, *args, **kwargs):
try:
# Check the cell for syntax errors. This way, the syntax error
# will show the original input, not the transformed input. The
# downside here is that IPython magic like %timeit will not work
# with transformed input (but on the other hand, IPython magic
# that doesn't expect transformed input will continue to work).
ast.parse(cell)
except SyntaxError:
pass
else:
cell = int_to_Integer(cell)
old_run_cell(cell, *args, **kwargs)
shell.run_cell = my_run_cell
def enable_automatic_symbols(shell):
"""Allow IPython to automatically create symbols (``isympy -a``). """
# XXX: This should perhaps use tokenize, like int_to_Integer() above.
# This would avoid re-executing the code, which can lead to subtle
# issues. For example:
#
# In [1]: a = 1
#
# In [2]: for i in range(10):
# ...: a += 1
# ...:
#
# In [3]: a
# Out[3]: 11
#
# In [4]: a = 1
#
# In [5]: for i in range(10):
# ...: a += 1
# ...: print b
# ...:
# b
# b
# b
# b
# b
# b
# b
# b
# b
# b
#
# In [6]: a
# Out[6]: 12
#
# Note how the for loop is executed again because `b` was not defined, but `a`
# was already incremented once, so the result is that it is incremented
# multiple times.
import re
re_nameerror = re.compile(
"name '(?P<symbol>[A-Za-z_][A-Za-z0-9_]*)' is not defined")
def _handler(self, etype, value, tb, tb_offset=None):
"""Handle :exc:`NameError` exception and allow injection of missing symbols. """
if etype is NameError and tb.tb_next and not tb.tb_next.tb_next:
match = re_nameerror.match(str(value))
if match is not None:
# XXX: Make sure Symbol is in scope. Otherwise you'll get infinite recursion.
self.run_cell("%(symbol)s = Symbol('%(symbol)s')" %
{'symbol': match.group("symbol")}, store_history=False)
try:
code = self.user_ns['In'][-1]
except (KeyError, IndexError):
pass
else:
self.run_cell(code, store_history=False)
return None
finally:
self.run_cell("del %s" % match.group("symbol"),
store_history=False)
stb = self.InteractiveTB.structured_traceback(
etype, value, tb, tb_offset=tb_offset)
self._showtraceback(etype, value, stb)
shell.set_custom_exc((NameError,), _handler)
def init_ipython_session(shell=None, argv=[], auto_symbols=False, auto_int_to_Integer=False):
"""Construct new IPython session. """
import IPython
if V(IPython.__version__) >= '0.11':
if not shell:
# use an app to parse the command line, and init config
# IPython 1.0 deprecates the frontend module, so we import directly
# from the terminal module to prevent a deprecation message from being
# shown.
if V(IPython.__version__) >= '1.0':
from IPython.terminal import ipapp
else:
from IPython.frontend.terminal import ipapp
app = ipapp.TerminalIPythonApp()
# don't draw IPython banner during initialization:
app.display_banner = False
app.initialize(argv)
shell = app.shell
if auto_symbols:
enable_automatic_symbols(shell)
if auto_int_to_Integer:
enable_automatic_int_sympification(shell)
return shell
else:
from IPython.Shell import make_IPython
return make_IPython(argv)
def init_python_session():
"""Construct new Python session. """
from code import InteractiveConsole
class SymPyConsole(InteractiveConsole):
"""An interactive console with readline support. """
def __init__(self):
ns_locals = dict()
InteractiveConsole.__init__(self, locals=ns_locals)
try:
import rlcompleter
import readline
except ImportError:
pass
else:
import os
import atexit
readline.set_completer(rlcompleter.Completer(ns_locals).complete)
readline.parse_and_bind('tab: complete')
if hasattr(readline, 'read_history_file'):
history = os.path.expanduser('~/.sympy-history')
try:
readline.read_history_file(history)
except OSError:
pass
atexit.register(readline.write_history_file, history)
return SymPyConsole()
def init_session(ipython=None, pretty_print=True, order=None,
use_unicode=None, use_latex=None, quiet=False, auto_symbols=False,
auto_int_to_Integer=False, str_printer=None, pretty_printer=None,
latex_printer=None, argv=[]):
"""
Initialize an embedded IPython or Python session. The IPython session is
initiated with the --pylab option, without the numpy imports, so that
matplotlib plotting can be interactive.
Parameters
==========
pretty_print: boolean
If True, use pretty_print to stringify;
if False, use sstrrepr to stringify.
order: string or None
There are a few different settings for this parameter:
lex (default), which is lexographic order;
grlex, which is graded lexographic order;
grevlex, which is reversed graded lexographic order;
old, which is used for compatibility reasons and for long expressions;
None, which sets it to lex.
use_unicode: boolean or None
If True, use unicode characters;
if False, do not use unicode characters.
use_latex: boolean or None
If True, use latex rendering if IPython GUI's;
if False, do not use latex rendering.
quiet: boolean
If True, init_session will not print messages regarding its status;
if False, init_session will print messages regarding its status.
auto_symbols: boolean
If True, IPython will automatically create symbols for you.
If False, it will not.
The default is False.
auto_int_to_Integer: boolean
If True, IPython will automatically wrap int literals with Integer, so
that things like 1/2 give Rational(1, 2).
If False, it will not.
The default is False.
ipython: boolean or None
If True, printing will initialize for an IPython console;
if False, printing will initialize for a normal console;
The default is None, which automatically determines whether we are in
an ipython instance or not.
str_printer: function, optional, default=None
A custom string printer function. This should mimic
sympy.printing.sstrrepr().
pretty_printer: function, optional, default=None
A custom pretty printer. This should mimic sympy.printing.pretty().
latex_printer: function, optional, default=None
A custom LaTeX printer. This should mimic sympy.printing.latex()
This should mimic sympy.printing.latex().
argv: list of arguments for IPython
See sympy.bin.isympy for options that can be used to initialize IPython.
See Also
========
sympy.interactive.printing.init_printing: for examples and the rest of the parameters.
Examples
========
>>> from sympy import init_session, Symbol, sin, sqrt
>>> sin(x) #doctest: +SKIP
NameError: name 'x' is not defined
>>> init_session() #doctest: +SKIP
>>> sin(x) #doctest: +SKIP
sin(x)
>>> sqrt(5) #doctest: +SKIP
___
\\/ 5
>>> init_session(pretty_print=False) #doctest: +SKIP
>>> sqrt(5) #doctest: +SKIP
sqrt(5)
>>> y + x + y**2 + x**2 #doctest: +SKIP
x**2 + x + y**2 + y
>>> init_session(order='grlex') #doctest: +SKIP
>>> y + x + y**2 + x**2 #doctest: +SKIP
x**2 + y**2 + x + y
>>> init_session(order='grevlex') #doctest: +SKIP
>>> y * x**2 + x * y**2 #doctest: +SKIP
x**2*y + x*y**2
>>> init_session(order='old') #doctest: +SKIP
>>> x**2 + y**2 + x + y #doctest: +SKIP
x + y + x**2 + y**2
>>> theta = Symbol('theta') #doctest: +SKIP
>>> theta #doctest: +SKIP
theta
>>> init_session(use_unicode=True) #doctest: +SKIP
>>> theta # doctest: +SKIP
\u03b8
"""
import sys
in_ipython = False
if ipython is not False:
try:
import IPython
except ImportError:
if ipython is True:
raise RuntimeError("IPython is not available on this system")
ip = None
else:
try:
from IPython import get_ipython
ip = get_ipython()
except ImportError:
ip = None
in_ipython = bool(ip)
if ipython is None:
ipython = in_ipython
if ipython is False:
ip = init_python_session()
mainloop = ip.interact
else:
ip = init_ipython_session(ip, argv=argv, auto_symbols=auto_symbols,
auto_int_to_Integer=auto_int_to_Integer)
if V(IPython.__version__) >= '0.11':
# runsource is gone, use run_cell instead, which doesn't
# take a symbol arg. The second arg is `store_history`,
# and False means don't add the line to IPython's history.
ip.runsource = lambda src, symbol='exec': ip.run_cell(src, False)
# Enable interactive plotting using pylab.
try:
ip.enable_pylab(import_all=False)
except Exception:
# Causes an import error if matplotlib is not installed.
# Causes other errors (depending on the backend) if there
# is no display, or if there is some problem in the
# backend, so we have a bare "except Exception" here
pass
if not in_ipython:
mainloop = ip.mainloop
if auto_symbols and (not ipython or V(IPython.__version__) < '0.11'):
raise RuntimeError("automatic construction of symbols is possible only in IPython 0.11 or above")
if auto_int_to_Integer and (not ipython or V(IPython.__version__) < '0.11'):
raise RuntimeError("automatic int to Integer transformation is possible only in IPython 0.11 or above")
_preexec_source = preexec_source
ip.runsource(_preexec_source, symbol='exec')
init_printing(pretty_print=pretty_print, order=order,
use_unicode=use_unicode, use_latex=use_latex, ip=ip,
str_printer=str_printer, pretty_printer=pretty_printer,
latex_printer=latex_printer)
message = _make_message(ipython, quiet, _preexec_source)
if not in_ipython:
print(message)
mainloop()
sys.exit('Exiting ...')
else:
print(message)
import atexit
atexit.register(lambda: print("Exiting ...\n"))
|
f37ffd2fae9d6f356fd147db3d1dce4cab71659eac31a78e89f3013d40c17a23 | from sympy.core.expr import Expr
from sympy.core.symbol import Dummy
from sympy.core.sympify import _sympify
from sympy.polys.polyerrors import CoercionFailed
from sympy.polys.polytools import Poly, parallel_poly_from_expr
from sympy.polys.domains import QQ
from sympy.polys.matrices import DomainMatrix
from sympy.polys.matrices.domainscalar import DomainScalar
class MutablePolyDenseMatrix:
"""
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
>>> 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]], x)
>>> pm1*v1
PolyMatrix([
[ x**2 + x, 0],
[x**3 - x + 1, 0]], ring=QQ[x])
>>> pm1.ring
ZZ[x]
>>> v1*pm1
PolyMatrix([
[ x**2, -x],
[-x**2, x]], ring=QQ[x])
>>> 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], x)
>>> v2.ring
QQ[x]
>>> pm2*v2
PolyMatrix([[x**2]], ring=QQ[x])
"""
def __new__(cls, *args, ring=None):
if not args:
# PolyMatrix(ring=QQ[x])
if ring is None:
raise TypeError("The ring needs to be specified for an empty PolyMatrix")
rows, cols, items, gens = 0, 0, [], ()
elif isinstance(args[0], list):
elements, gens = args[0], args[1:]
if not elements:
# PolyMatrix([])
rows, cols, items = 0, 0, []
elif isinstance(elements[0], (list, tuple)):
# PolyMatrix([[1, 2]], x)
rows, cols = len(elements), len(elements[0])
items = [e for row in elements for e in row]
else:
# PolyMatrix([1, 2], x)
rows, cols = len(elements), 1
items = elements
elif [type(a) for a in args[:3]] == [int, int, list]:
# PolyMatrix(2, 2, [1, 2, 3, 4], x)
rows, cols, items, gens = args[0], args[1], args[2], args[3:]
elif [type(a) for a in args[:3]] == [int, int, type(lambda: 0)]:
# PolyMatrix(2, 2, lambda i, j: i+j, x)
rows, cols, func, gens = args[0], args[1], args[2], args[3:]
items = [func(i, j) for i in range(rows) for j in range(cols)]
else:
raise TypeError("Invalid arguments")
# PolyMatrix([[1]], x, y) vs PolyMatrix([[1]], (x, y))
if len(gens) == 1 and isinstance(gens[0], tuple):
gens = gens[0]
# gens is now a tuple (x, y)
return cls.from_list(rows, cols, items, gens, ring)
@classmethod
def from_list(cls, rows, cols, items, gens, ring):
# items can be Expr, Poly, or a mix of Expr and Poly
items = [_sympify(item) for item in items]
if items and all(isinstance(item, Poly) for item in items):
polys = True
else:
polys = False
# Identify the ring for the polys
if ring is not None:
# Parse a domain string like 'QQ[x]'
if isinstance(ring, str):
ring = Poly(0, Dummy(), domain=ring).domain
elif polys:
p = items[0]
for p2 in items[1:]:
p, _ = p.unify(p2)
ring = p.domain[p.gens]
else:
items, info = parallel_poly_from_expr(items, gens, field=True)
ring = info['domain'][info['gens']]
polys = True
# Efficiently convert when all elements are Poly
if polys:
p_ring = Poly(0, ring.symbols, domain=ring.domain)
to_ring = ring.ring.from_list
convert_poly = lambda p: to_ring(p.unify(p_ring)[0].rep.rep)
elements = [convert_poly(p) for p in items]
else:
convert_expr = ring.from_sympy
elements = [convert_expr(e.as_expr()) for e in items]
# Convert to domain elements and construct DomainMatrix
elements_lol = [[elements[i*cols + j] for j in range(cols)] for i in range(rows)]
dm = DomainMatrix(elements_lol, (rows, cols), ring)
return cls.from_dm(dm)
@classmethod
def from_dm(cls, dm):
obj = super().__new__(cls)
dm = dm.to_sparse()
R = dm.domain
obj._dm = dm
obj.ring = R
obj.domain = R.domain
obj.gens = R.symbols
return obj
def to_Matrix(self):
return self._dm.to_Matrix()
@classmethod
def from_Matrix(cls, other, *gens, ring=None):
return cls(*other.shape, other.flat(), *gens, ring=ring)
def set_gens(self, gens):
return self.from_Matrix(self.to_Matrix(), gens)
def __repr__(self):
if self.rows * self.cols:
return 'Poly' + repr(self.to_Matrix())[:-1] + f', ring={self.ring})'
else:
return f'PolyMatrix({self.rows}, {self.cols}, [], ring={self.ring})'
@property
def shape(self):
return self._dm.shape
@property
def rows(self):
return self.shape[0]
@property
def cols(self):
return self.shape[1]
def __len__(self):
return self.rows * self.cols
def __getitem__(self, key):
def to_poly(v):
ground = self._dm.domain.domain
gens = self._dm.domain.symbols
return Poly(v.to_dict(), gens, domain=ground)
dm = self._dm
if isinstance(key, slice):
items = dm.flat()[key]
return [to_poly(item) for item in items]
elif isinstance(key, int):
i, j = divmod(key, self.cols)
e = dm[i,j]
return to_poly(e.element)
i, j = key
if isinstance(i, int) and isinstance(j, int):
return to_poly(dm[i, j].element)
else:
return self.from_dm(dm[i, j])
def __eq__(self, other):
if not isinstance(self, type(other)):
return NotImplemented
return self._dm == other._dm
def __add__(self, other):
if isinstance(other, type(self)):
return self.from_dm(self._dm + other._dm)
return NotImplemented
def __sub__(self, other):
if isinstance(other, type(self)):
return self.from_dm(self._dm - other._dm)
return NotImplemented
def __mul__(self, other):
if isinstance(other, type(self)):
return self.from_dm(self._dm * other._dm)
elif isinstance(other, int):
other = _sympify(other)
if isinstance(other, Expr):
Kx = self.ring
try:
other_ds = DomainScalar(Kx.from_sympy(other), Kx)
except (CoercionFailed, ValueError):
other_ds = DomainScalar.from_sympy(other)
return self.from_dm(self._dm * other_ds)
return NotImplemented
def __rmul__(self, other):
if isinstance(other, int):
other = _sympify(other)
if isinstance(other, Expr):
other_ds = DomainScalar.from_sympy(other)
return self.from_dm(other_ds * self._dm)
return NotImplemented
def __truediv__(self, other):
if isinstance(other, Poly):
other = other.as_expr()
elif isinstance(other, int):
other = _sympify(other)
if not isinstance(other, Expr):
return NotImplemented
other = self.domain.from_sympy(other)
inverse = self.ring.convert_from(1/other, self.domain)
inverse = DomainScalar(inverse, self.ring)
dm = self._dm * inverse
return self.from_dm(dm)
def __neg__(self):
return self.from_dm(-self._dm)
def transpose(self):
return self.from_dm(self._dm.transpose())
def row_join(self, other):
dm = DomainMatrix.hstack(self._dm, other._dm)
return self.from_dm(dm)
def col_join(self, other):
dm = DomainMatrix.vstack(self._dm, other._dm)
return self.from_dm(dm)
def applyfunc(self, func):
M = self.to_Matrix().applyfunc(func)
return self.from_Matrix(M, self.gens)
@classmethod
def eye(cls, n, gens):
return cls.from_dm(DomainMatrix.eye(n, QQ[gens]))
@classmethod
def zeros(cls, m, n, gens):
return cls.from_dm(DomainMatrix.zeros((m, n), QQ[gens]))
def rref(self, simplify='ignore', normalize_last='ignore'):
# If this is K[x] then computes RREF in ground field K.
if not (self.domain.is_Field and all(p.is_ground for p in self)):
raise ValueError("PolyMatrix rref is only for ground field elements")
dm = self._dm
dm_ground = dm.convert_to(dm.domain.domain)
dm_rref, pivots = dm_ground.rref()
dm_rref = dm_rref.convert_to(dm.domain)
return self.from_dm(dm_rref), pivots
def nullspace(self):
# If this is K[x] then computes nullspace in ground field K.
if not (self.domain.is_Field and all(p.is_ground for p in self)):
raise ValueError("PolyMatrix nullspace is only for ground field elements")
dm = self._dm
K, Kx = self.domain, self.ring
dm_null_rows = dm.convert_to(K).nullspace().convert_to(Kx)
dm_null = dm_null_rows.transpose()
dm_basis = [dm_null[:,i] for i in range(dm_null.shape[1])]
return [self.from_dm(dmvec) for dmvec in dm_basis]
def rank(self):
return self.cols - len(self.nullspace())
MutablePolyMatrix = PolyMatrix = MutablePolyDenseMatrix
|
f947807be86ace6ed711aac8edbeaed90e151527e389b53808f601bcd4f39c48 | """OO layer for several polynomial representations. """
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
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 __truediv__(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 __rtruediv__(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
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 __bool__(f):
return not dmp_zero_p(f.rep, f.lev)
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):
num, den = f.num, f.den
if n < 0:
num, den, n = den, num, -n
return f.per(dmp_pow(num, n, f.lev, f.dom),
dmp_pow(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 __truediv__(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 __rtruediv__(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
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 __bool__(f):
return not dmp_zero_p(f.num, f.lev)
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 __pos__(f):
return f
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 __truediv__(f, g):
if isinstance(g, ANP):
return f.quo(g)
else:
try:
return f.quo(f.per(g))
except (CoercionFailed, TypeError):
return NotImplemented
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 __bool__(f):
return bool(f.rep)
|
8e5793bb37777997bdcceb36960cb60c77baef31d9471152b565aeb6465ce992 | """Polynomial manipulation algorithms and algebraic objects. """
__all__ = [
'Poly', 'PurePoly', 'poly_from_expr', 'parallel_poly_from_expr', 'degree',
'total_degree', 'degree_list', 'LC', 'LM', 'LT', 'pdiv', 'prem', 'pquo',
'pexquo', 'div', 'rem', 'quo', 'exquo', 'half_gcdex', 'gcdex', 'invert',
'subresultants', 'resultant', 'discriminant', 'cofactors', 'gcd_list',
'gcd', 'lcm_list', 'lcm', 'terms_gcd', 'trunc', 'monic', 'content',
'primitive', 'compose', 'decompose', 'sturm', 'gff_list', 'gff',
'sqf_norm', 'sqf_part', 'sqf_list', 'sqf', 'factor_list', 'factor',
'intervals', 'refine_root', 'count_roots', 'real_roots', 'nroots',
'ground_roots', 'nth_power_roots_poly', 'cancel', 'reduced', 'groebner',
'is_zero_dimensional', 'GroebnerBasis', 'poly',
'symmetrize', 'horner', 'interpolate', 'rational_interpolate', 'viete',
'together',
'BasePolynomialError', 'ExactQuotientFailed', 'PolynomialDivisionFailed',
'OperationNotSupported', 'HeuristicGCDFailed', 'HomomorphismFailed',
'IsomorphismFailed', 'ExtraneousFactors', 'EvaluationFailed',
'RefinementFailed', 'CoercionFailed', 'NotInvertible', 'NotReversible',
'NotAlgebraic', 'DomainError', 'PolynomialError', 'UnificationFailed',
'GeneratorsError', 'GeneratorsNeeded', 'ComputationFailed',
'UnivariatePolynomialError', 'MultivariatePolynomialError',
'PolificationFailed', 'OptionError', 'FlagError',
'minpoly', 'minimal_polynomial', 'primitive_element', 'field_isomorphism',
'to_number_field', 'isolate',
'itermonomials', 'Monomial',
'lex', 'grlex', 'grevlex', 'ilex', 'igrlex', 'igrevlex',
'CRootOf', 'rootof', 'RootOf', 'ComplexRootOf', 'RootSum',
'roots',
'Domain', 'FiniteField', 'IntegerRing', 'RationalField', 'RealField',
'ComplexField', 'PythonFiniteField', 'GMPYFiniteField',
'PythonIntegerRing', 'GMPYIntegerRing', 'PythonRational',
'GMPYRationalField', 'AlgebraicField', 'PolynomialRing', 'FractionField',
'ExpressionDomain', 'FF_python', 'FF_gmpy', 'ZZ_python', 'ZZ_gmpy',
'QQ_python', 'QQ_gmpy', 'GF', 'FF', 'ZZ', 'QQ', 'ZZ_I', 'QQ_I', 'RR',
'CC', 'EX', 'EXRAW',
'construct_domain',
'swinnerton_dyer_poly', 'cyclotomic_poly', 'symmetric_poly',
'random_poly', 'interpolating_poly',
'jacobi_poly', 'chebyshevt_poly', 'chebyshevu_poly', 'hermite_poly',
'legendre_poly', 'laguerre_poly',
'apart', 'apart_list', 'assemble_partfrac_list',
'Options',
'ring', 'xring', 'vring', 'sring',
'field', 'xfield', 'vfield', 'sfield'
]
from .polytools import (Poly, PurePoly, poly_from_expr,
parallel_poly_from_expr, degree, total_degree, degree_list, LC, LM,
LT, pdiv, prem, pquo, pexquo, div, rem, quo, exquo, half_gcdex, gcdex,
invert, subresultants, resultant, discriminant, cofactors, gcd_list,
gcd, lcm_list, lcm, terms_gcd, trunc, monic, content, primitive,
compose, decompose, sturm, gff_list, gff, sqf_norm, sqf_part,
sqf_list, sqf, factor_list, factor, intervals, refine_root,
count_roots, real_roots, nroots, ground_roots, nth_power_roots_poly,
cancel, reduced, groebner, is_zero_dimensional, GroebnerBasis, poly)
from .polyfuncs import (symmetrize, horner, interpolate,
rational_interpolate, viete)
from .rationaltools import together
from .polyerrors import (BasePolynomialError, ExactQuotientFailed,
PolynomialDivisionFailed, OperationNotSupported, HeuristicGCDFailed,
HomomorphismFailed, IsomorphismFailed, ExtraneousFactors,
EvaluationFailed, RefinementFailed, CoercionFailed, NotInvertible,
NotReversible, NotAlgebraic, DomainError, PolynomialError,
UnificationFailed, GeneratorsError, GeneratorsNeeded,
ComputationFailed, UnivariatePolynomialError,
MultivariatePolynomialError, PolificationFailed, OptionError,
FlagError)
from .numberfields import (minpoly, minimal_polynomial, primitive_element,
field_isomorphism, to_number_field, isolate)
from .monomials import itermonomials, Monomial
from .orderings import lex, grlex, grevlex, ilex, igrlex, igrevlex
from .rootoftools import CRootOf, rootof, RootOf, ComplexRootOf, RootSum
from .polyroots import roots
from .domains import (Domain, FiniteField, IntegerRing, RationalField,
RealField, ComplexField, PythonFiniteField, GMPYFiniteField,
PythonIntegerRing, GMPYIntegerRing, PythonRational, GMPYRationalField,
AlgebraicField, PolynomialRing, FractionField, ExpressionDomain,
FF_python, FF_gmpy, ZZ_python, ZZ_gmpy, QQ_python, QQ_gmpy, GF, FF,
ZZ, QQ, ZZ_I, QQ_I, RR, CC, EX, EXRAW)
from .constructor import construct_domain
from .specialpolys import (swinnerton_dyer_poly, cyclotomic_poly,
symmetric_poly, random_poly, interpolating_poly)
from .orthopolys import (jacobi_poly, chebyshevt_poly, chebyshevu_poly,
hermite_poly, legendre_poly, laguerre_poly)
from .partfrac import apart, apart_list, assemble_partfrac_list
from .polyoptions import Options
from .rings import ring, xring, vring, sring
from .fields import field, xfield, vfield, sfield
|
87eb2657c43c2c02eb538267874bcd946ad263723ea35a44f4c26d328a6ca44e | """Sparse polynomial rings. """
from typing import Any, Dict
from operator import add, mul, lt, le, gt, ge
from functools import reduce
from types import GeneratorType
from sympy.core.compatibility import is_sequence
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:`~.MonomialOrder` 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:`~.MonomialOrder` 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:`~.MonomialOrder` 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 # noqa:
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
>>> 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:
coeffs = sum([ list(rep.values()) for rep in reps ], [])
opt.domain, coeffs_dom = construct_domain(coeffs, opt=opt)
coeff_map = dict(zip(coeffs, coeffs_dom))
reps = [{m: coeff_map[c] for m, c in rep.items()} for rep in reps]
_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, str):
return _symbols(symbols, seq=True) if symbols else ()
elif isinstance(symbols, Expr):
return (symbols,)
elif is_sequence(symbols):
if all(isinstance(s, str) 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 = {} # type: Dict[Any, Any]
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, str):
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, orig_domain=None):
domain_new = self.domain_new
poly = self.zero
for monom, coeff in element.items():
coeff = domain_new(coeff, orig_domain)
if coeff:
poly[monom] = coeff
return poly
def from_terms(self, element, orig_domain=None):
return self.from_dict(dict(element), orig_domain)
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)))
else:
# XXX: Use as_base_exp() to handle Pow(x, n) and also exp(n)
# XXX: E can be a generator e.g. sring([exp(2)]) -> ZZ[E]
base, exp = expr.as_base_exp()
if exp.is_Integer and exp > 1:
return _rebuild(base)**int(exp)
else:
return self.ground_new(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, str):
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, self.ring.domain)
else:
return new_ring.from_dict(self, self.ring.domain)
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
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():
negative = ring.domain.is_negative(coeff)
sign = " - " if negative else " + "
sexpvs.append(sign)
if expv == zm:
scoeff = printer._print(coeff)
if negative and scoeff.startswith("-"):
scoeff = scoeff[1:]
else:
if negative:
coeff = -coeff
if coeff != self.ring.one:
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 actual 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 = multinomial_coefficients(len(self), n).items()
monomial_mulpow = self.ring.monomial_mulpow
zero_monom = self.ring.zero_monom
terms = self.items()
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
elif monom in poly:
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__ = __truediv__
__rfloordiv__ = __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:`~.MonomialOrder` 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:`~.MonomialOrder` 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:`~.MonomialOrder` 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)
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 = p.mul_ground(cp)
q = q.mul_ground(cq)
# Make canonical with respect to sign or quadrant in the case of ZZ_I
# or QQ_I. This ensures that the LC of the denominator is canonical by
# multiplying top and bottom by a unit of the ring.
u = q.canonical_unit()
if u == domain.one:
p, q = p, q
elif u == -domain.one:
p, q = -p, -q
else:
p = p.mul_ground(u)
q = q.mul_ground(u)
return p, q
def canonical_unit(f):
domain = f.ring.domain
return domain.canonical_unit(f.LC)
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)
|
214d8947d33535e8796aca0fc0333bbcc8a1b4a02fe888e57737d9f3411a948e | """Low-level linear systems solver. """
from sympy.utilities.exceptions import SymPyDeprecationWarning
from sympy.utilities.iterables import connected_components
from sympy.core.sympify import sympify
from sympy.core.numbers import Integer, Rational
from sympy.matrices.dense import MutableDenseMatrix
from sympy.polys.domains import ZZ, QQ
from sympy.polys.domains import EX
from sympy.polys.rings import sring
from sympy.polys.polyerrors import NotInvertible
from sympy.polys.domainmatrix import DomainMatrix
class PolyNonlinearError(Exception):
"""Raised by solve_lin_sys for nonlinear equations"""
pass
class RawMatrix(MutableDenseMatrix):
"""
XXX: This class is broken by design. Use DomainMatrix if you want a matrix
over the polys domains or Matrix for a matrix with Expr elements. The
RawMatrix class will be removed/broken in future in order to reestablish
the invariant that the elements of a Matrix should be of type Expr.
"""
_sympify = staticmethod(lambda x: x)
def __init__(self, *args, **kwargs):
SymPyDeprecationWarning(
feature="RawMatrix class",
useinstead="DomainMatrix or Matrix",
issue=21405,
deprecated_since_version="1.9"
).warn()
domain = ZZ
for i in range(self.rows):
for j in range(self.cols):
val = self[i,j]
if getattr(val, 'is_Poly', False):
K = val.domain[val.gens]
val_sympy = val.as_expr()
elif hasattr(val, 'parent'):
K = val.parent()
val_sympy = K.to_sympy(val)
elif isinstance(val, (int, Integer)):
K = ZZ
val_sympy = sympify(val)
elif isinstance(val, Rational):
K = QQ
val_sympy = val
else:
for K in ZZ, QQ:
if K.of_type(val):
val_sympy = K.to_sympy(val)
break
else:
raise TypeError
domain = domain.unify(K)
self[i,j] = val_sympy
self.ring = domain
def eqs_to_matrix(eqs_coeffs, eqs_rhs, gens, domain):
"""Get matrix from linear equations in dict format.
Explanation
===========
Get the matrix representation of a system of linear equations represented
as dicts with low-level DomainElement coefficients. This is an
*internal* function that is used by solve_lin_sys.
Parameters
==========
eqs_coeffs: list[dict[Symbol, DomainElement]]
The left hand sides of the equations as dicts mapping from symbols to
coefficients where the coefficients are instances of
DomainElement.
eqs_rhs: list[DomainElements]
The right hand sides of the equations as instances of
DomainElement.
gens: list[Symbol]
The unknowns in the system of equations.
domain: Domain
The domain for coefficients of both lhs and rhs.
Returns
=======
The augmented matrix representation of the system as a DomainMatrix.
Examples
========
>>> from sympy import symbols, ZZ
>>> from sympy.polys.solvers import eqs_to_matrix
>>> x, y = symbols('x, y')
>>> eqs_coeff = [{x:ZZ(1), y:ZZ(1)}, {x:ZZ(1), y:ZZ(-1)}]
>>> eqs_rhs = [ZZ(0), ZZ(-1)]
>>> eqs_to_matrix(eqs_coeff, eqs_rhs, [x, y], ZZ)
DomainMatrix([[1, 1, 0], [1, -1, 1]], (2, 3), ZZ)
See also
========
solve_lin_sys: Uses :func:`~eqs_to_matrix` internally
"""
sym2index = {x: n for n, x in enumerate(gens)}
nrows = len(eqs_coeffs)
ncols = len(gens) + 1
rows = [[domain.zero] * ncols for _ in range(nrows)]
for row, eq_coeff, eq_rhs in zip(rows, eqs_coeffs, eqs_rhs):
for sym, coeff in eq_coeff.items():
row[sym2index[sym]] = domain.convert(coeff)
row[-1] = -domain.convert(eq_rhs)
return DomainMatrix(rows, (nrows, ncols), domain)
def sympy_eqs_to_ring(eqs, symbols):
"""Convert a system of equations from Expr to a PolyRing
Explanation
===========
High-level functions like ``solve`` expect Expr as inputs but can use
``solve_lin_sys`` internally. This function converts equations from
``Expr`` to the low-level poly types used by the ``solve_lin_sys``
function.
Parameters
==========
eqs: List of Expr
A list of equations as Expr instances
symbols: List of Symbol
A list of the symbols that are the unknowns in the system of
equations.
Returns
=======
Tuple[List[PolyElement], Ring]: The equations as PolyElement instances
and the ring of polynomials within which each equation is represented.
Examples
========
>>> from sympy import symbols
>>> from sympy.polys.solvers import sympy_eqs_to_ring
>>> a, x, y = symbols('a, x, y')
>>> eqs = [x-y, x+a*y]
>>> eqs_ring, ring = sympy_eqs_to_ring(eqs, [x, y])
>>> eqs_ring
[x - y, x + a*y]
>>> type(eqs_ring[0])
<class 'sympy.polys.rings.PolyElement'>
>>> ring
ZZ(a)[x,y]
With the equations in this form they can be passed to ``solve_lin_sys``:
>>> from sympy.polys.solvers import solve_lin_sys
>>> solve_lin_sys(eqs_ring, ring)
{y: 0, x: 0}
"""
try:
K, eqs_K = sring(eqs, symbols, field=True, extension=True)
except NotInvertible:
# https://github.com/sympy/sympy/issues/18874
K, eqs_K = sring(eqs, symbols, domain=EX)
return eqs_K, K.to_domain()
def solve_lin_sys(eqs, ring, _raw=True):
"""Solve a system of linear equations from a PolynomialRing
Explanation
===========
Solves a system of linear equations given as PolyElement instances of a
PolynomialRing. The basic arithmetic is carried out using instance of
DomainElement which is more efficient than :class:`~sympy.core.expr.Expr`
for the most common inputs.
While this is a public function it is intended primarily for internal use
so its interface is not necessarily convenient. Users are suggested to use
the :func:`sympy.solvers.solveset.linsolve` function (which uses this
function internally) instead.
Parameters
==========
eqs: list[PolyElement]
The linear equations to be solved as elements of a
PolynomialRing (assumed equal to zero).
ring: PolynomialRing
The polynomial ring from which eqs are drawn. The generators of this
ring are the unkowns to be solved for and the domain of the ring is
the domain of the coefficients of the system of equations.
_raw: bool
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.
Returns
=======
``None`` if the system has no solution.
dict[Symbol, Expr] if _raw=False
dict[Symbol, DomainElement] if _raw=True.
Examples
========
>>> from sympy import symbols
>>> from sympy.polys.solvers import solve_lin_sys, sympy_eqs_to_ring
>>> x, y = symbols('x, y')
>>> eqs = [x - y, x + y - 2]
>>> eqs_ring, ring = sympy_eqs_to_ring(eqs, [x, y])
>>> solve_lin_sys(eqs_ring, ring)
{y: 1, x: 1}
Passing ``_raw=False`` returns the same result except that the keys are
``Expr`` rather than low-level poly types.
>>> solve_lin_sys(eqs_ring, ring, _raw=False)
{x: 1, y: 1}
See also
========
sympy_eqs_to_ring: prepares the inputs to ``solve_lin_sys``.
linsolve: ``linsolve`` uses ``solve_lin_sys`` internally.
sympy.solvers.solvers.solve: ``solve`` uses ``solve_lin_sys`` internally.
"""
as_expr = not _raw
assert ring.domain.is_Field
eqs_dict = [dict(eq) for eq in eqs]
one_monom = ring.one.monoms()[0]
zero = ring.domain.zero
eqs_rhs = []
eqs_coeffs = []
for eq_dict in eqs_dict:
eq_rhs = eq_dict.pop(one_monom, zero)
eq_coeffs = {}
for monom, coeff in eq_dict.items():
if sum(monom) != 1:
msg = "Nonlinear term encountered in solve_lin_sys"
raise PolyNonlinearError(msg)
eq_coeffs[ring.gens[monom.index(1)]] = coeff
if not eq_coeffs:
if not eq_rhs:
continue
else:
return None
eqs_rhs.append(eq_rhs)
eqs_coeffs.append(eq_coeffs)
result = _solve_lin_sys(eqs_coeffs, eqs_rhs, ring)
if result is not None and as_expr:
def to_sympy(x):
as_expr = getattr(x, 'as_expr', None)
if as_expr:
return as_expr()
else:
return ring.domain.to_sympy(x)
tresult = {to_sympy(sym): to_sympy(val) for sym, val in result.items()}
# Remove 1.0x
result = {}
for k, v in tresult.items():
if k.is_Mul:
c, s = k.as_coeff_Mul()
result[s] = v/c
else:
result[k] = v
return result
def _solve_lin_sys(eqs_coeffs, eqs_rhs, ring):
"""Solve a linear system from dict of PolynomialRing coefficients
Explanation
===========
This is an **internal** function used by :func:`solve_lin_sys` after the
equations have been preprocessed. The role of this function is to split
the system into connected components and pass those to
:func:`_solve_lin_sys_component`.
Examples
========
Setup a system for $x-y=0$ and $x+y=2$ and solve:
>>> from sympy import symbols, sring
>>> from sympy.polys.solvers import _solve_lin_sys
>>> x, y = symbols('x, y')
>>> R, (xr, yr) = sring([x, y], [x, y])
>>> eqs = [{xr:R.one, yr:-R.one}, {xr:R.one, yr:R.one}]
>>> eqs_rhs = [R.zero, -2*R.one]
>>> _solve_lin_sys(eqs, eqs_rhs, R)
{y: 1, x: 1}
See also
========
solve_lin_sys: This function is used internally by :func:`solve_lin_sys`.
"""
V = ring.gens
E = []
for eq_coeffs in eqs_coeffs:
syms = list(eq_coeffs)
E.extend(zip(syms[:-1], syms[1:]))
G = V, E
components = connected_components(G)
sym2comp = {}
for n, component in enumerate(components):
for sym in component:
sym2comp[sym] = n
subsystems = [([], []) for _ in range(len(components))]
for eq_coeff, eq_rhs in zip(eqs_coeffs, eqs_rhs):
sym = next(iter(eq_coeff), None)
sub_coeff, sub_rhs = subsystems[sym2comp[sym]]
sub_coeff.append(eq_coeff)
sub_rhs.append(eq_rhs)
sol = {}
for subsystem in subsystems:
subsol = _solve_lin_sys_component(subsystem[0], subsystem[1], ring)
if subsol is None:
return None
sol.update(subsol)
return sol
def _solve_lin_sys_component(eqs_coeffs, eqs_rhs, ring):
"""Solve a linear system from dict of PolynomialRing coefficients
Explanation
===========
This is an **internal** function used by :func:`solve_lin_sys` after the
equations have been preprocessed. After :func:`_solve_lin_sys` splits the
system into connected components this function is called for each
component. The system of equations is solved using Gauss-Jordan
elimination with division followed by back-substitution.
Examples
========
Setup a system for $x-y=0$ and $x+y=2$ and solve:
>>> from sympy import symbols, sring
>>> from sympy.polys.solvers import _solve_lin_sys_component
>>> x, y = symbols('x, y')
>>> R, (xr, yr) = sring([x, y], [x, y])
>>> eqs = [{xr:R.one, yr:-R.one}, {xr:R.one, yr:R.one}]
>>> eqs_rhs = [R.zero, -2*R.one]
>>> _solve_lin_sys_component(eqs, eqs_rhs, R)
{y: 1, x: 1}
See also
========
solve_lin_sys: This function is used internally by :func:`solve_lin_sys`.
"""
# transform from equations to matrix form
matrix = eqs_to_matrix(eqs_coeffs, eqs_rhs, ring.gens, ring.domain)
# convert to a field for rref
if not matrix.domain.is_Field:
matrix = matrix.to_field()
# solve by row-reduction
echelon, pivots = matrix.rref()
# construct the returnable form of the solutions
keys = ring.gens
if pivots and pivots[-1] == len(keys):
return None
if len(pivots) == len(keys):
sol = []
for s in [row[-1] for row in echelon.rep.to_ddm()]:
a = s
sol.append(a)
sols = dict(zip(keys, sol))
else:
sols = {}
g = ring.gens
# Extract ground domain coefficients and convert to the ring:
if hasattr(ring, 'ring'):
convert = ring.ring.ground_new
else:
convert = ring.ground_new
echelon = echelon.rep.to_ddm()
vals_set = {v for row in echelon for v in row}
vals_map = {v: convert(v) for v in vals_set}
echelon = [[vals_map[eij] for eij in ei] for ei in echelon]
for i, p in enumerate(pivots):
v = echelon[i][-1] - sum(echelon[i][j]*g[j] for j in range(p+1, len(g)) if echelon[i][j])
sols[keys[p]] = v
return sols
|
3e077c83014cfc8d935eee9c8d82c8afe1e5b386d524f05ea128d4f2b4fe298d | """Useful utilities for higher level polynomial classes. """
from sympy.core import (S, Add, Mul, Pow, Eq, Expr,
expand_mul, expand_multinomial)
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*)$", re.MULTILINE)
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 len(roots) > 1 and 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)
illegal = [S.NaN, S.Infinity, S.NegativeInfinity, S.ComplexInfinity]
illegal_types = [type(obj) for obj in illegal]
finf = [float(i) for i in illegal[1:3]]
def _not_a_coeff(expr):
"""Do not treat NaN and infinities as valid polynomial coefficients. """
if type(expr) in illegal_types or expr in finf:
return True
if type(expr) is float and float(expr) != expr:
return True # nan
return # could be
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 factor is S.ImaginaryUnit
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, Eq)):
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:
"""
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::
>>> 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
|
0a3175bf0ee2096de572cbbd2deabef1ebf1727ae49bc9a14cf54e4f46665d84 | import re
import fnmatch
# XXX Python 2 unicode import test.
# May remove after deprecating python 2.7.
message_unicode_A = \
"File contains a unicode character : %s, line %s. " \
"But with no encoding header. " \
"See https://www.python.org/dev/peps/pep-0263/ " \
"and add '# coding=utf-8'"
message_unicode_B = \
"File contains a unicode character : %s, line %s. " \
"But not in the whitelist. " \
"Add the file to the whitelist in " + __file__
message_unicode_C = \
"File contains a unicode character : %s, line %s. " \
"And is in the whitelist, but without the encoding header. " \
"See https://www.python.org/dev/peps/pep-0263/ " \
"and add '# coding=utf-8'."
message_unicode_D = \
"File does not contain a unicode character : %s." \
"but is in the whitelist. " \
"Remove the file from the whitelist in " + __file__
message_unicode_E = \
"File does not contain a unicode character : %s." \
"but contains the header '# coding=utf-8' or equivalent." \
"Remove the header."
encoding_header_re = re.compile(
r'^[ \t\f]*#.*?coding[:=][ \t]*([-_.a-zA-Z0-9]+)')
# Whitelist pattern for files which can have unicode.
unicode_whitelist = [
# Author names can include non-ASCII characters
r'*/bin/authors_update.py',
# These files have functions and test functions for unicode input and
# output.
r'*/sympy/testing/tests/test_code_quality.py',
r'*/sympy/physics/vector/tests/test_printing.py',
r'*/physics/quantum/tests/test_printing.py',
r'*/sympy/vector/tests/test_printing.py',
r'*/sympy/parsing/tests/test_sympy_parser.py',
r'*/sympy/printing/pretty/tests/test_pretty.py',
r'*/sympy/printing/tests/test_conventions.py',
r'*/sympy/printing/tests/test_preview.py',
r'*/liealgebras/type_g.py',
r'*/liealgebras/weyl_group.py',
r'*/liealgebras/tests/test_type_G.py',
# wigner.py and polarization.py have unicode doctests. These probably
# don't need to be there but some of the examples that are there are
# pretty ugly without use_unicode (matrices need to be wrapped across
# multiple lines etc)
r'*/sympy/physics/wigner.py',
r'*/sympy/physics/optics/polarization.py',
# joint.py uses some unicode for variable names in the docstrings
r'*/sympy/physics/mechanics/joint.py',
]
unicode_strict_whitelist = [
r'*/sympy/parsing/latex/_antlr/__init__.py',
]
def _test_this_file_encoding(
fname, test_file,
unicode_whitelist=unicode_whitelist,
unicode_strict_whitelist=unicode_strict_whitelist):
"""Test helper function for python 2 importability test
This test checks whether the file has
# coding=utf-8
or
# -*- coding: utf-8 -*-
line if there is a unicode character in the code
The test may have to operate on filewise manner, so it had moved
to a separate process.
May remove after deprecating python 2.7.
"""
has_coding_utf8 = False
has_unicode = False
is_in_whitelist = False
is_in_strict_whitelist = False
for patt in unicode_whitelist:
if fnmatch.fnmatch(fname, patt):
is_in_whitelist = True
break
for patt in unicode_strict_whitelist:
if fnmatch.fnmatch(fname, patt):
is_in_strict_whitelist = True
is_in_whitelist = True
break
if is_in_whitelist:
for idx, line in enumerate(test_file):
if idx in (0, 1):
match = encoding_header_re.match(line)
if match and match.group(1).lower() == 'utf-8':
has_coding_utf8 = True
try:
line.encode(encoding='ascii')
except (UnicodeEncodeError, UnicodeDecodeError):
has_unicode = True
if has_coding_utf8 is False:
assert False, \
message_unicode_C % (fname, idx + 1)
if not has_unicode and not is_in_strict_whitelist:
assert False, message_unicode_D % fname
else:
for idx, line in enumerate(test_file):
if idx in (0, 1):
match = encoding_header_re.match(line)
if match and match.group(1).lower() == 'utf-8':
has_coding_utf8 = True
try:
line.encode(encoding='ascii')
except (UnicodeEncodeError, UnicodeDecodeError):
has_unicode = True
if has_coding_utf8:
assert False, \
message_unicode_B % (fname, idx + 1)
else:
assert False, \
message_unicode_A % (fname, idx + 1)
if not has_unicode and has_coding_utf8:
assert False, \
message_unicode_E % fname
|
b7ea2c2c585b5a92440738e7616abc5b0e58cf5d76cabb9fab1d45720a6ba1df | from sympy import S, Rational, gcd, sqrt, sign, symbols, Complement
from sympy.core import Basic, Tuple, diff, expand, Eq, Integer
from sympy.core.compatibility import ordered
from sympy.core.symbol import _symbol
from sympy.solvers import solveset, nonlinsolve, diophantine
from sympy.polys import total_degree
from sympy.geometry import Point
from sympy.ntheory.factor_ import core
class ImplicitRegion(Basic):
"""
Represents an implicit region in space.
Examples
========
>>> from sympy import Eq
>>> from sympy.abc import x, y, z, t
>>> from sympy.vector import ImplicitRegion
>>> ImplicitRegion((x, y), x**2 + y**2 - 4)
ImplicitRegion((x, y), x**2 + y**2 - 4)
>>> ImplicitRegion((x, y), Eq(y*x, 1))
ImplicitRegion((x, y), x*y - 1)
>>> parabola = ImplicitRegion((x, y), y**2 - 4*x)
>>> parabola.degree
2
>>> parabola.equation
-4*x + y**2
>>> parabola.rational_parametrization(t)
(4/t**2, 4/t)
>>> r = ImplicitRegion((x, y, z), Eq(z, x**2 + y**2))
>>> r.variables
(x, y, z)
>>> r.singular_points()
FiniteSet((0, 0, 0))
>>> r.regular_point()
(-10, -10, 200)
Parameters
==========
variables : tuple to map variables in implicit equation to base scalars.
equation : An expression or Eq denoting the implicit equation of the region.
"""
def __new__(cls, variables, equation):
if not isinstance(variables, Tuple):
variables = Tuple(*variables)
if isinstance(equation, Eq):
equation = equation.lhs - equation.rhs
return super().__new__(cls, variables, equation)
@property
def variables(self):
return self.args[0]
@property
def equation(self):
return self.args[1]
@property
def degree(self):
return total_degree(self.equation)
def regular_point(self):
"""
Returns a point on the implicit region.
Examples
========
>>> from sympy.abc import x, y, z
>>> from sympy.vector import ImplicitRegion
>>> circle = ImplicitRegion((x, y), (x + 2)**2 + (y - 3)**2 - 16)
>>> circle.regular_point()
(-2, -1)
>>> parabola = ImplicitRegion((x, y), x**2 - 4*y)
>>> parabola.regular_point()
(0, 0)
>>> r = ImplicitRegion((x, y, z), (x + y + z)**4)
>>> r.regular_point()
(-10, -10, 20)
References
==========
- Erik Hillgarter, "Rational Points on Conics", Diploma Thesis, RISC-Linz,
J. Kepler Universitat Linz, 1996. Availaible:
https://www3.risc.jku.at/publications/download/risc_1355/Rational%20Points%20on%20Conics.pdf
"""
equation = self.equation
if len(self.variables) == 1:
return (list(solveset(equation, self.variables[0], domain=S.Reals))[0],)
elif len(self.variables) == 2:
if self.degree == 2:
coeffs = a, b, c, d, e, f = conic_coeff(self.variables, equation)
if b**2 == 4*a*c:
x_reg, y_reg = self._regular_point_parabola(*coeffs)
else:
x_reg, y_reg = self._regular_point_ellipse(*coeffs)
return x_reg, y_reg
if len(self.variables) == 3:
x, y, z = self.variables
for x_reg in range(-10, 10):
for y_reg in range(-10, 10):
if not solveset(equation.subs({x: x_reg, y: y_reg}), self.variables[2], domain=S.Reals).is_empty:
return (x_reg, y_reg, list(solveset(equation.subs({x: x_reg, y: y_reg})))[0])
if len(self.singular_points()) != 0:
return list[self.singular_points()][0]
raise NotImplementedError()
def _regular_point_parabola(self, a, b, c, d, e, f):
ok = (a, d) != (0, 0) and (c, e) != (0, 0) and b**2 == 4*a*c and (a, c) != (0, 0)
if not ok:
raise ValueError("Rational Point on the conic does not exist")
if a != 0:
d_dash, f_dash = (4*a*e - 2*b*d, 4*a*f - d**2)
if d_dash != 0:
y_reg = -f_dash/d_dash
x_reg = -(d + b*y_reg)/(2*a)
else:
ok = False
elif c != 0:
d_dash, f_dash = (4*c*d - 2*b*e, 4*c*f - e**2)
if d_dash != 0:
x_reg = -f_dash/d_dash
y_reg = -(e + b*x_reg)/(2*c)
else:
ok = False
if ok:
return x_reg, y_reg
else:
raise ValueError("Rational Point on the conic does not exist")
def _regular_point_ellipse(self, a, b, c, d, e, f):
D = 4*a*c - b**2
ok = D
if not ok:
raise ValueError("Rational Point on the conic does not exist")
if a == 0 and c == 0:
K = -1
L = 4*(d*e - b*f)
elif c != 0:
K = D
L = 4*c**2*d**2 - 4*b*c*d*e + 4*a*c*e**2 + 4*b**2*c*f - 16*a*c**2*f
else:
K = D
L = 4*a**2*e**2 - 4*b*a*d*e + 4*b**2*a*f
ok = L != 0 and not(K > 0 and L < 0)
if not ok:
raise ValueError("Rational Point on the conic does not exist")
K = Rational(K).limit_denominator(10**12)
L = Rational(L).limit_denominator(10**12)
k1, k2 = K.p, K.q
l1, l2 = L.p, L.q
g = gcd(k2, l2)
a1 = (l2*k2)/g
b1 = (k1*l2)/g
c1 = -(l1*k2)/g
a2 = sign(a1)*core(abs(a1), 2)
r1 = sqrt(a1/a2)
b2 = sign(b1)*core(abs(b1), 2)
r2 = sqrt(b1/b2)
c2 = sign(c1)*core(abs(c1), 2)
r3 = sqrt(c1/c2)
g = gcd(gcd(a2, b2), c2)
a2 = a2/g
b2 = b2/g
c2 = c2/g
g1 = gcd(a2, b2)
a2 = a2/g1
b2 = b2/g1
c2 = c2*g1
g2 = gcd(a2,c2)
a2 = a2/g2
b2 = b2*g2
c2 = c2/g2
g3 = gcd(b2, c2)
a2 = a2*g3
b2 = b2/g3
c2 = c2/g3
x, y, z = symbols("x y z")
eq = a2*x**2 + b2*y**2 + c2*z**2
solutions = diophantine(eq)
if len(solutions) == 0:
raise ValueError("Rational Point on the conic does not exist")
flag = False
for sol in solutions:
syms = Tuple(*sol).free_symbols
rep = {s: 3 for s in syms}
sol_z = sol[2]
if sol_z == 0:
flag = True
continue
if not (isinstance(sol_z, Integer) or isinstance(sol_z, int)):
syms_z = sol_z.free_symbols
if len(syms_z) == 1:
p = next(iter(syms_z))
p_values = Complement(S.Integers, solveset(Eq(sol_z, 0), p, S.Integers))
rep[p] = next(iter(p_values))
if len(syms_z) == 2:
p, q = list(ordered(syms_z))
for i in S.Integers:
subs_sol_z = sol_z.subs(p, i)
q_values = Complement(S.Integers, solveset(Eq(subs_sol_z, 0), q, S.Integers))
if not q_values.is_empty:
rep[p] = i
rep[q] = next(iter(q_values))
break
if len(syms) != 0:
x, y, z = tuple(s.subs(rep) for s in sol)
else:
x, y, z = sol
flag = False
break
if flag:
raise ValueError("Rational Point on the conic does not exist")
x = (x*g3)/r1
y = (y*g2)/r2
z = (z*g1)/r3
x = x/z
y = y/z
if a == 0 and c == 0:
x_reg = (x + y - 2*e)/(2*b)
y_reg = (x - y - 2*d)/(2*b)
elif c != 0:
x_reg = (x - 2*d*c + b*e)/K
y_reg = (y - b*x_reg - e)/(2*c)
else:
y_reg = (x - 2*e*a + b*d)/K
x_reg = (y - b*y_reg - d)/(2*a)
return x_reg, y_reg
def singular_points(self):
"""
Returns a set of singular points of the region.
The singular points are those points on the region
where all partial derivatives vanish.
Examples
========
>>> from sympy.abc import x, y
>>> from sympy.vector import ImplicitRegion
>>> I = ImplicitRegion((x, y), (y-1)**2 -x**3 + 2*x**2 -x)
>>> I.singular_points()
FiniteSet((1, 1))
"""
eq_list = [self.equation]
for var in self.variables:
eq_list += [diff(self.equation, var)]
return nonlinsolve(eq_list, list(self.variables))
def multiplicity(self, point):
"""
Returns the multiplicity of a singular point on the region.
A singular point (x,y) of region is said to be of multiplicity m
if all the partial derivatives off to order m - 1 vanish there.
Examples
========
>>> from sympy.abc import x, y, z
>>> from sympy.vector import ImplicitRegion
>>> I = ImplicitRegion((x, y, z), x**2 + y**3 - z**4)
>>> I.singular_points()
FiniteSet((0, 0, 0))
>>> I.multiplicity((0, 0, 0))
2
"""
if isinstance(point, Point):
point = point.args
modified_eq = self.equation
for i, var in enumerate(self.variables):
modified_eq = modified_eq.subs(var, var + point[i])
modified_eq = expand(modified_eq)
if len(modified_eq.args) != 0:
terms = modified_eq.args
m = min([total_degree(term) for term in terms])
else:
terms = modified_eq
m = total_degree(terms)
return m
def rational_parametrization(self, parameters=('t', 's'), reg_point=None):
"""
Returns the rational parametrization of implict region.
Examples
========
>>> from sympy import Eq
>>> from sympy.abc import x, y, z, s, t
>>> from sympy.vector import ImplicitRegion
>>> parabola = ImplicitRegion((x, y), y**2 - 4*x)
>>> parabola.rational_parametrization()
(4/t**2, 4/t)
>>> circle = ImplicitRegion((x, y), Eq(x**2 + y**2, 4))
>>> circle.rational_parametrization()
(4*t/(t**2 + 1), 4*t**2/(t**2 + 1) - 2)
>>> I = ImplicitRegion((x, y), x**3 + x**2 - y**2)
>>> I.rational_parametrization()
(t**2 - 1, t*(t**2 - 1))
>>> cubic_curve = ImplicitRegion((x, y), x**3 + x**2 - y**2)
>>> cubic_curve.rational_parametrization(parameters=(t))
(t**2 - 1, t*(t**2 - 1))
>>> sphere = ImplicitRegion((x, y, z), x**2 + y**2 + z**2 - 4)
>>> sphere.rational_parametrization(parameters=(t, s))
(-2 + 4/(s**2 + t**2 + 1), 4*s/(s**2 + t**2 + 1), 4*t/(s**2 + t**2 + 1))
For some conics, regular_points() is unable to find a point on curve.
To calulcate the parametric representation in such cases, user need
to determine a point on the region and pass it using reg_point.
>>> c = ImplicitRegion((x, y), (x - 1/2)**2 + (y)**2 - (1/4)**2)
>>> c.rational_parametrization(reg_point=(3/4, 0))
(0.75 - 0.5/(t**2 + 1), -0.5*t/(t**2 + 1))
References
==========
- Christoph M. Hoffmann, "Conversion Methods between Parametric and
Implicit Curves and Surfaces", Purdue e-Pubs, 1990. Available:
https://docs.lib.purdue.edu/cgi/viewcontent.cgi?article=1827&context=cstech
"""
equation = self.equation
degree = self.degree
if degree == 1:
if len(self.variables) == 1:
return (equation,)
elif len(self.variables) == 2:
x, y = self.variables
y_par = list(solveset(equation, y))[0]
return x, y_par
else:
raise NotImplementedError()
point = ()
# Finding the (n - 1) fold point of the monoid of degree
if degree == 2:
# For degree 2 curves, either a regular point or a singular point can be used.
if reg_point is not None:
# Using point provided by the user as regular point
point = reg_point
else:
if len(self.singular_points()) != 0:
point = list(self.singular_points())[0]
else:
point = self.regular_point()
if len(self.singular_points()) != 0:
singular_points = self.singular_points()
for spoint in singular_points:
syms = Tuple(*spoint).free_symbols
rep = {s: 2 for s in syms}
if len(syms) != 0:
spoint = tuple(s.subs(rep) for s in spoint)
if self.multiplicity(spoint) == degree - 1:
point = spoint
break
if len(point) == 0:
# The region in not a monoid
raise NotImplementedError()
modified_eq = equation
# Shifting the region such that fold point moves to origin
for i, var in enumerate(self.variables):
modified_eq = modified_eq.subs(var, var + point[i])
modified_eq = expand(modified_eq)
hn = hn_1 = 0
for term in modified_eq.args:
if total_degree(term) == degree:
hn += term
else:
hn_1 += term
hn_1 = -1*hn_1
if not isinstance(parameters, tuple):
parameters = (parameters,)
if len(self.variables) == 2:
parameter1 = parameters[0]
if parameter1 == 's':
# To avoid name conflict between parameters
s = _symbol('s_', real=True)
else:
s = _symbol('s', real=True)
t = _symbol(parameter1, real=True)
hn = hn.subs({self.variables[0]: s, self.variables[1]: t})
hn_1 = hn_1.subs({self.variables[0]: s, self.variables[1]: t})
x_par = (s*(hn_1/hn)).subs(s, 1) + point[0]
y_par = (t*(hn_1/hn)).subs(s, 1) + point[1]
return x_par, y_par
elif len(self.variables) == 3:
parameter1, parameter2 = parameters
if parameter1 == 'r' or parameter2 == 'r':
# To avoid name conflict between parameters
r = _symbol('r_', real=True)
else:
r = _symbol('r', real=True)
s = _symbol(parameter2, real=True)
t = _symbol(parameter1, real=True)
hn = hn.subs({self.variables[0]: r, self.variables[1]: s, self.variables[2]: t})
hn_1 = hn_1.subs({self.variables[0]: r, self.variables[1]: s, self.variables[2]: t})
x_par = (r*(hn_1/hn)).subs(r, 1) + point[0]
y_par = (s*(hn_1/hn)).subs(r, 1) + point[1]
z_par = (t*(hn_1/hn)).subs(r, 1) + point[2]
return x_par, y_par, z_par
raise NotImplementedError()
def conic_coeff(variables, equation):
if total_degree(equation) != 2:
raise ValueError()
x = variables[0]
y = variables[1]
equation = expand(equation)
a = equation.coeff(x**2)
b = equation.coeff(x*y)
c = equation.coeff(y**2)
d = equation.coeff(x, 1).coeff(y, 0)
e = equation.coeff(y, 1).coeff(x, 0)
f = equation.coeff(x, 0).coeff(y, 0)
return a, b, c, d, e, f
|
714fba28efee26ba8b5f4cf9ad0284ae9274ed2256c4c992f995b4757d3147bd | """Geometrical Points.
Contains
========
Point
Point2D
Point3D
When methods of Point require 1 or more points as arguments, they
can be passed as a sequence of coordinates or Points:
>>> from sympy.geometry.point import Point
>>> Point(1, 1).is_collinear((2, 2), (3, 4))
False
>>> Point(1, 1).is_collinear(Point(2, 2), Point(3, 4))
False
"""
import warnings
from sympy.core import S, sympify, Expr
from sympy.core.compatibility import is_sequence
from sympy.core.containers import Tuple
from sympy.simplify import nsimplify, simplify
from sympy.geometry.exceptions import GeometryError
from sympy.functions.elementary.miscellaneous import sqrt
from sympy.functions.elementary.complexes import im
from sympy.matrices import Matrix
from sympy.core.numbers import Float
from sympy.core.parameters import global_parameters
from sympy.core.add import Add
from sympy.utilities.iterables import uniq
from sympy.utilities.misc import filldedent, func_name, Undecidable
from .entity import GeometryEntity
class Point(GeometryEntity):
"""A point in a n-dimensional Euclidean space.
Parameters
==========
coords : sequence of n-coordinate values. In the special
case where n=2 or 3, a Point2D or Point3D will be created
as appropriate.
evaluate : if `True` (default), all floats are turn into
exact types.
dim : number of coordinates the point should have. If coordinates
are unspecified, they are padded with zeros.
on_morph : indicates what should happen when the number of
coordinates of a point need to be changed by adding or
removing zeros. Possible values are `'warn'`, `'error'`, or
`ignore` (default). No warning or error is given when `*args`
is empty and `dim` is given. An error is always raised when
trying to remove nonzero coordinates.
Attributes
==========
length
origin: A `Point` representing the origin of the
appropriately-dimensioned space.
Raises
======
TypeError : When instantiating with anything but a Point or sequence
ValueError : when instantiating with a sequence with length < 2 or
when trying to reduce dimensions if keyword `on_morph='error'` is
set.
See Also
========
sympy.geometry.line.Segment : Connects two Points
Examples
========
>>> from sympy.geometry import Point
>>> from sympy.abc import x
>>> Point(1, 2, 3)
Point3D(1, 2, 3)
>>> Point([1, 2])
Point2D(1, 2)
>>> Point(0, x)
Point2D(0, x)
>>> Point(dim=4)
Point(0, 0, 0, 0)
Floats are automatically converted to Rational unless the
evaluate flag is False:
>>> Point(0.5, 0.25)
Point2D(1/2, 1/4)
>>> Point(0.5, 0.25, evaluate=False)
Point2D(0.5, 0.25)
"""
is_Point = True
def __new__(cls, *args, **kwargs):
evaluate = kwargs.get('evaluate', global_parameters.evaluate)
on_morph = kwargs.get('on_morph', 'ignore')
# unpack into coords
coords = args[0] if len(args) == 1 else args
# check args and handle quickly handle Point instances
if isinstance(coords, Point):
# even if we're mutating the dimension of a point, we
# don't reevaluate its coordinates
evaluate = False
if len(coords) == kwargs.get('dim', len(coords)):
return coords
if not is_sequence(coords):
raise TypeError(filldedent('''
Expecting sequence of coordinates, not `{}`'''
.format(func_name(coords))))
# A point where only `dim` is specified is initialized
# to zeros.
if len(coords) == 0 and kwargs.get('dim', None):
coords = (S.Zero,)*kwargs.get('dim')
coords = Tuple(*coords)
dim = kwargs.get('dim', len(coords))
if len(coords) < 2:
raise ValueError(filldedent('''
Point requires 2 or more coordinates or
keyword `dim` > 1.'''))
if len(coords) != dim:
message = ("Dimension of {} needs to be changed "
"from {} to {}.").format(coords, len(coords), dim)
if on_morph == 'ignore':
pass
elif on_morph == "error":
raise ValueError(message)
elif on_morph == 'warn':
warnings.warn(message)
else:
raise ValueError(filldedent('''
on_morph value should be 'error',
'warn' or 'ignore'.'''))
if any(coords[dim:]):
raise ValueError('Nonzero coordinates cannot be removed.')
if any(a.is_number and im(a) for a in coords):
raise ValueError('Imaginary coordinates are not permitted.')
if not all(isinstance(a, Expr) for a in coords):
raise TypeError('Coordinates must be valid SymPy expressions.')
# pad with zeros appropriately
coords = coords[:dim] + (S.Zero,)*(dim - len(coords))
# Turn any Floats into rationals and simplify
# any expressions before we instantiate
if evaluate:
coords = coords.xreplace({
f: simplify(nsimplify(f, rational=True))
for f in coords.atoms(Float)})
# return 2D or 3D instances
if len(coords) == 2:
kwargs['_nocheck'] = True
return Point2D(*coords, **kwargs)
elif len(coords) == 3:
kwargs['_nocheck'] = True
return Point3D(*coords, **kwargs)
# the general Point
return GeometryEntity.__new__(cls, *coords)
def __abs__(self):
"""Returns the distance between this point and the origin."""
origin = Point([0]*len(self))
return Point.distance(origin, self)
def __add__(self, other):
"""Add other to self by incrementing self's coordinates by
those of other.
Notes
=====
>>> from sympy.geometry.point import Point
When sequences of coordinates are passed to Point methods, they
are converted to a Point internally. This __add__ method does
not do that so if floating point values are used, a floating
point result (in terms of SymPy Floats) will be returned.
>>> Point(1, 2) + (.1, .2)
Point2D(1.1, 2.2)
If this is not desired, the `translate` method can be used or
another Point can be added:
>>> Point(1, 2).translate(.1, .2)
Point2D(11/10, 11/5)
>>> Point(1, 2) + Point(.1, .2)
Point2D(11/10, 11/5)
See Also
========
sympy.geometry.point.Point.translate
"""
try:
s, o = Point._normalize_dimension(self, Point(other, evaluate=False))
except TypeError:
raise GeometryError("Don't know how to add {} and a Point object".format(other))
coords = [simplify(a + b) for a, b in zip(s, o)]
return Point(coords, evaluate=False)
def __contains__(self, item):
return item in self.args
def __truediv__(self, divisor):
"""Divide point's coordinates by a factor."""
divisor = sympify(divisor)
coords = [simplify(x/divisor) for x in self.args]
return Point(coords, evaluate=False)
def __eq__(self, other):
if not isinstance(other, Point) or len(self.args) != len(other.args):
return False
return self.args == other.args
def __getitem__(self, key):
return self.args[key]
def __hash__(self):
return hash(self.args)
def __iter__(self):
return self.args.__iter__()
def __len__(self):
return len(self.args)
def __mul__(self, factor):
"""Multiply point's coordinates by a factor.
Notes
=====
>>> from sympy.geometry.point import Point
When multiplying a Point by a floating point number,
the coordinates of the Point will be changed to Floats:
>>> Point(1, 2)*0.1
Point2D(0.1, 0.2)
If this is not desired, the `scale` method can be used or
else only multiply or divide by integers:
>>> Point(1, 2).scale(1.1, 1.1)
Point2D(11/10, 11/5)
>>> Point(1, 2)*11/10
Point2D(11/10, 11/5)
See Also
========
sympy.geometry.point.Point.scale
"""
factor = sympify(factor)
coords = [simplify(x*factor) for x in self.args]
return Point(coords, evaluate=False)
def __rmul__(self, factor):
"""Multiply a factor by point's coordinates."""
return self.__mul__(factor)
def __neg__(self):
"""Negate the point."""
coords = [-x for x in self.args]
return Point(coords, evaluate=False)
def __sub__(self, other):
"""Subtract two points, or subtract a factor from this point's
coordinates."""
return self + [-x for x in other]
@classmethod
def _normalize_dimension(cls, *points, **kwargs):
"""Ensure that points have the same dimension.
By default `on_morph='warn'` is passed to the
`Point` constructor."""
# if we have a built-in ambient dimension, use it
dim = getattr(cls, '_ambient_dimension', None)
# override if we specified it
dim = kwargs.get('dim', dim)
# if no dim was given, use the highest dimensional point
if dim is None:
dim = max(i.ambient_dimension for i in points)
if all(i.ambient_dimension == dim for i in points):
return list(points)
kwargs['dim'] = dim
kwargs['on_morph'] = kwargs.get('on_morph', 'warn')
return [Point(i, **kwargs) for i in points]
@staticmethod
def affine_rank(*args):
"""The affine rank of a set of points is the dimension
of the smallest affine space containing all the points.
For example, if the points lie on a line (and are not all
the same) their affine rank is 1. If the points lie on a plane
but not a line, their affine rank is 2. By convention, the empty
set has affine rank -1."""
if len(args) == 0:
return -1
# make sure we're genuinely points
# and translate every point to the origin
points = Point._normalize_dimension(*[Point(i) for i in args])
origin = points[0]
points = [i - origin for i in points[1:]]
m = Matrix([i.args for i in points])
# XXX fragile -- what is a better way?
return m.rank(iszerofunc = lambda x:
abs(x.n(2)) < 1e-12 if x.is_number else x.is_zero)
@property
def ambient_dimension(self):
"""Number of components this point has."""
return getattr(self, '_ambient_dimension', len(self))
@classmethod
def are_coplanar(cls, *points):
"""Return True if there exists a plane in which all the points
lie. A trivial True value is returned if `len(points) < 3` or
all Points are 2-dimensional.
Parameters
==========
A set of points
Raises
======
ValueError : if less than 3 unique points are given
Returns
=======
boolean
Examples
========
>>> from sympy import Point3D
>>> p1 = Point3D(1, 2, 2)
>>> p2 = Point3D(2, 7, 2)
>>> p3 = Point3D(0, 0, 2)
>>> p4 = Point3D(1, 1, 2)
>>> Point3D.are_coplanar(p1, p2, p3, p4)
True
>>> p5 = Point3D(0, 1, 3)
>>> Point3D.are_coplanar(p1, p2, p3, p5)
False
"""
if len(points) <= 1:
return True
points = cls._normalize_dimension(*[Point(i) for i in points])
# quick exit if we are in 2D
if points[0].ambient_dimension == 2:
return True
points = list(uniq(points))
return Point.affine_rank(*points) <= 2
def distance(self, other):
"""The Euclidean distance between self and another GeometricEntity.
Returns
=======
distance : number or symbolic expression.
Raises
======
TypeError : if other is not recognized as a GeometricEntity or is a
GeometricEntity for which distance is not defined.
See Also
========
sympy.geometry.line.Segment.length
sympy.geometry.point.Point.taxicab_distance
Examples
========
>>> from sympy.geometry import Point, Line
>>> p1, p2 = Point(1, 1), Point(4, 5)
>>> l = Line((3, 1), (2, 2))
>>> p1.distance(p2)
5
>>> p1.distance(l)
sqrt(2)
The computed distance may be symbolic, too:
>>> from sympy.abc import x, y
>>> p3 = Point(x, y)
>>> p3.distance((0, 0))
sqrt(x**2 + y**2)
"""
if not isinstance(other, GeometryEntity):
try:
other = Point(other, dim=self.ambient_dimension)
except TypeError:
raise TypeError("not recognized as a GeometricEntity: %s" % type(other))
if isinstance(other, Point):
s, p = Point._normalize_dimension(self, Point(other))
return sqrt(Add(*((a - b)**2 for a, b in zip(s, p))))
distance = getattr(other, 'distance', None)
if distance is None:
raise TypeError("distance between Point and %s is not defined" % type(other))
return distance(self)
def dot(self, p):
"""Return dot product of self with another Point."""
if not is_sequence(p):
p = Point(p) # raise the error via Point
return Add(*(a*b for a, b in zip(self, p)))
def equals(self, other):
"""Returns whether the coordinates of self and other agree."""
# a point is equal to another point if all its components are equal
if not isinstance(other, Point) or len(self) != len(other):
return False
return all(a.equals(b) for a, b in zip(self, other))
def evalf(self, prec=None, **options):
"""Evaluate the coordinates of the point.
This method will, where possible, create and return a new Point
where the coordinates are evaluated as floating point numbers to
the precision indicated (default=15).
Parameters
==========
prec : int
Returns
=======
point : Point
Examples
========
>>> from sympy import Point, Rational
>>> p1 = Point(Rational(1, 2), Rational(3, 2))
>>> p1
Point2D(1/2, 3/2)
>>> p1.evalf()
Point2D(0.5, 1.5)
"""
coords = [x.evalf(prec, **options) for x in self.args]
return Point(*coords, evaluate=False)
def intersection(self, other):
"""The intersection between this point and another GeometryEntity.
Parameters
==========
other : GeometryEntity or sequence of coordinates
Returns
=======
intersection : list of Points
Notes
=====
The return value will either be an empty list if there is no
intersection, otherwise it will contain this point.
Examples
========
>>> from sympy import Point
>>> p1, p2, p3 = Point(0, 0), Point(1, 1), Point(0, 0)
>>> p1.intersection(p2)
[]
>>> p1.intersection(p3)
[Point2D(0, 0)]
"""
if not isinstance(other, GeometryEntity):
other = Point(other)
if isinstance(other, Point):
if self == other:
return [self]
p1, p2 = Point._normalize_dimension(self, other)
if p1 == self and p1 == p2:
return [self]
return []
return other.intersection(self)
def is_collinear(self, *args):
"""Returns `True` if there exists a line
that contains `self` and `points`. Returns `False` otherwise.
A trivially True value is returned if no points are given.
Parameters
==========
args : sequence of Points
Returns
=======
is_collinear : boolean
See Also
========
sympy.geometry.line.Line
Examples
========
>>> from sympy import Point
>>> from sympy.abc import x
>>> p1, p2 = Point(0, 0), Point(1, 1)
>>> p3, p4, p5 = Point(2, 2), Point(x, x), Point(1, 2)
>>> Point.is_collinear(p1, p2, p3, p4)
True
>>> Point.is_collinear(p1, p2, p3, p5)
False
"""
points = (self,) + args
points = Point._normalize_dimension(*[Point(i) for i in points])
points = list(uniq(points))
return Point.affine_rank(*points) <= 1
def is_concyclic(self, *args):
"""Do `self` and the given sequence of points lie in a circle?
Returns True if the set of points are concyclic and
False otherwise. A trivial value of True is returned
if there are fewer than 2 other points.
Parameters
==========
args : sequence of Points
Returns
=======
is_concyclic : boolean
Examples
========
>>> from sympy import Point
Define 4 points that are on the unit circle:
>>> p1, p2, p3, p4 = Point(1, 0), (0, 1), (-1, 0), (0, -1)
>>> p1.is_concyclic() == p1.is_concyclic(p2, p3, p4) == True
True
Define a point not on that circle:
>>> p = Point(1, 1)
>>> p.is_concyclic(p1, p2, p3)
False
"""
points = (self,) + args
points = Point._normalize_dimension(*[Point(i) for i in points])
points = list(uniq(points))
if not Point.affine_rank(*points) <= 2:
return False
origin = points[0]
points = [p - origin for p in points]
# points are concyclic if they are coplanar and
# there is a point c so that ||p_i-c|| == ||p_j-c|| for all
# i and j. Rearranging this equation gives us the following
# condition: the matrix `mat` must not a pivot in the last
# column.
mat = Matrix([list(i) + [i.dot(i)] for i in points])
rref, pivots = mat.rref()
if len(origin) not in pivots:
return True
return False
@property
def is_nonzero(self):
"""True if any coordinate is nonzero, False if every coordinate is zero,
and None if it cannot be determined."""
is_zero = self.is_zero
if is_zero is None:
return None
return not is_zero
def is_scalar_multiple(self, p):
"""Returns whether each coordinate of `self` is a scalar
multiple of the corresponding coordinate in point p.
"""
s, o = Point._normalize_dimension(self, Point(p))
# 2d points happen a lot, so optimize this function call
if s.ambient_dimension == 2:
(x1, y1), (x2, y2) = s.args, o.args
rv = (x1*y2 - x2*y1).equals(0)
if rv is None:
raise Undecidable(filldedent(
'''can't determine if %s is a scalar multiple of
%s''' % (s, o)))
# if the vectors p1 and p2 are linearly dependent, then they must
# be scalar multiples of each other
m = Matrix([s.args, o.args])
return m.rank() < 2
@property
def is_zero(self):
"""True if every coordinate is zero, False if any coordinate is not zero,
and None if it cannot be determined."""
nonzero = [x.is_nonzero for x in self.args]
if any(nonzero):
return False
if any(x is None for x in nonzero):
return None
return True
@property
def length(self):
"""
Treating a Point as a Line, this returns 0 for the length of a Point.
Examples
========
>>> from sympy import Point
>>> p = Point(0, 1)
>>> p.length
0
"""
return S.Zero
def midpoint(self, p):
"""The midpoint between self and point p.
Parameters
==========
p : Point
Returns
=======
midpoint : Point
See Also
========
sympy.geometry.line.Segment.midpoint
Examples
========
>>> from sympy.geometry import Point
>>> p1, p2 = Point(1, 1), Point(13, 5)
>>> p1.midpoint(p2)
Point2D(7, 3)
"""
s, p = Point._normalize_dimension(self, Point(p))
return Point([simplify((a + b)*S.Half) for a, b in zip(s, p)])
@property
def origin(self):
"""A point of all zeros of the same ambient dimension
as the current point"""
return Point([0]*len(self), evaluate=False)
@property
def orthogonal_direction(self):
"""Returns a non-zero point that is orthogonal to the
line containing `self` and the origin.
Examples
========
>>> from sympy.geometry import Line, Point
>>> a = Point(1, 2, 3)
>>> a.orthogonal_direction
Point3D(-2, 1, 0)
>>> b = _
>>> Line(b, b.origin).is_perpendicular(Line(a, a.origin))
True
"""
dim = self.ambient_dimension
# if a coordinate is zero, we can put a 1 there and zeros elsewhere
if self[0].is_zero:
return Point([1] + (dim - 1)*[0])
if self[1].is_zero:
return Point([0,1] + (dim - 2)*[0])
# if the first two coordinates aren't zero, we can create a non-zero
# orthogonal vector by swapping them, negating one, and padding with zeros
return Point([-self[1], self[0]] + (dim - 2)*[0])
@staticmethod
def project(a, b):
"""Project the point `a` onto the line between the origin
and point `b` along the normal direction.
Parameters
==========
a : Point
b : Point
Returns
=======
p : Point
See Also
========
sympy.geometry.line.LinearEntity.projection
Examples
========
>>> from sympy.geometry import Line, Point
>>> a = Point(1, 2)
>>> b = Point(2, 5)
>>> z = a.origin
>>> p = Point.project(a, b)
>>> Line(p, a).is_perpendicular(Line(p, b))
True
>>> Point.is_collinear(z, p, b)
True
"""
a, b = Point._normalize_dimension(Point(a), Point(b))
if b.is_zero:
raise ValueError("Cannot project to the zero vector.")
return b*(a.dot(b) / b.dot(b))
def taxicab_distance(self, p):
"""The Taxicab Distance from self to point p.
Returns the sum of the horizontal and vertical distances to point p.
Parameters
==========
p : Point
Returns
=======
taxicab_distance : The sum of the horizontal
and vertical distances to point p.
See Also
========
sympy.geometry.point.Point.distance
Examples
========
>>> from sympy.geometry import Point
>>> p1, p2 = Point(1, 1), Point(4, 5)
>>> p1.taxicab_distance(p2)
7
"""
s, p = Point._normalize_dimension(self, Point(p))
return Add(*(abs(a - b) for a, b in zip(s, p)))
def canberra_distance(self, p):
"""The Canberra Distance from self to point p.
Returns the weighted sum of horizontal and vertical distances to
point p.
Parameters
==========
p : Point
Returns
=======
canberra_distance : The weighted sum of horizontal and vertical
distances to point p. The weight used is the sum of absolute values
of the coordinates.
Examples
========
>>> from sympy.geometry import Point
>>> p1, p2 = Point(1, 1), Point(3, 3)
>>> p1.canberra_distance(p2)
1
>>> p1, p2 = Point(0, 0), Point(3, 3)
>>> p1.canberra_distance(p2)
2
Raises
======
ValueError when both vectors are zero.
See Also
========
sympy.geometry.point.Point.distance
"""
s, p = Point._normalize_dimension(self, Point(p))
if self.is_zero and p.is_zero:
raise ValueError("Cannot project to the zero vector.")
return Add(*((abs(a - b)/(abs(a) + abs(b))) for a, b in zip(s, p)))
@property
def unit(self):
"""Return the Point that is in the same direction as `self`
and a distance of 1 from the origin"""
return self / abs(self)
n = evalf
class Point2D(Point):
"""A point in a 2-dimensional Euclidean space.
Parameters
==========
coords : sequence of 2 coordinate values.
Attributes
==========
x
y
length
Raises
======
TypeError
When trying to add or subtract points with different dimensions.
When trying to create a point with more than two dimensions.
When `intersection` is called with object other than a Point.
See Also
========
sympy.geometry.line.Segment : Connects two Points
Examples
========
>>> from sympy.geometry import Point2D
>>> from sympy.abc import x
>>> Point2D(1, 2)
Point2D(1, 2)
>>> Point2D([1, 2])
Point2D(1, 2)
>>> Point2D(0, x)
Point2D(0, x)
Floats are automatically converted to Rational unless the
evaluate flag is False:
>>> Point2D(0.5, 0.25)
Point2D(1/2, 1/4)
>>> Point2D(0.5, 0.25, evaluate=False)
Point2D(0.5, 0.25)
"""
_ambient_dimension = 2
def __new__(cls, *args, _nocheck=False, **kwargs):
if not _nocheck:
kwargs['dim'] = 2
args = Point(*args, **kwargs)
return GeometryEntity.__new__(cls, *args)
def __contains__(self, item):
return item == self
@property
def bounds(self):
"""Return a tuple (xmin, ymin, xmax, ymax) representing the bounding
rectangle for the geometric figure.
"""
return (self.x, self.y, self.x, self.y)
def rotate(self, angle, pt=None):
"""Rotate ``angle`` radians counterclockwise about Point ``pt``.
See Also
========
translate, scale
Examples
========
>>> from sympy import Point2D, pi
>>> t = Point2D(1, 0)
>>> t.rotate(pi/2)
Point2D(0, 1)
>>> t.rotate(pi/2, (2, 0))
Point2D(2, -1)
"""
from sympy import cos, sin, Point
c = cos(angle)
s = sin(angle)
rv = self
if pt is not None:
pt = Point(pt, dim=2)
rv -= pt
x, y = rv.args
rv = Point(c*x - s*y, s*x + c*y)
if pt is not None:
rv += pt
return rv
def scale(self, x=1, y=1, pt=None):
"""Scale the coordinates of the Point by multiplying by
``x`` and ``y`` after subtracting ``pt`` -- default is (0, 0) --
and then adding ``pt`` back again (i.e. ``pt`` is the point of
reference for the scaling).
See Also
========
rotate, translate
Examples
========
>>> from sympy import Point2D
>>> t = Point2D(1, 1)
>>> t.scale(2)
Point2D(2, 1)
>>> t.scale(2, 2)
Point2D(2, 2)
"""
if pt:
pt = Point(pt, dim=2)
return self.translate(*(-pt).args).scale(x, y).translate(*pt.args)
return Point(self.x*x, self.y*y)
def transform(self, matrix):
"""Return the point after applying the transformation described
by the 3x3 Matrix, ``matrix``.
See Also
========
sympy.geometry.point.Point2D.rotate
sympy.geometry.point.Point2D.scale
sympy.geometry.point.Point2D.translate
"""
if not (matrix.is_Matrix and matrix.shape == (3, 3)):
raise ValueError("matrix must be a 3x3 matrix")
x, y = self.args
return Point(*(Matrix(1, 3, [x, y, 1])*matrix).tolist()[0][:2])
def translate(self, x=0, y=0):
"""Shift the Point by adding x and y to the coordinates of the Point.
See Also
========
sympy.geometry.point.Point2D.rotate, scale
Examples
========
>>> from sympy import Point2D
>>> t = Point2D(0, 1)
>>> t.translate(2)
Point2D(2, 1)
>>> t.translate(2, 2)
Point2D(2, 3)
>>> t + Point2D(2, 2)
Point2D(2, 3)
"""
return Point(self.x + x, self.y + y)
@property
def coordinates(self):
"""
Returns the two coordinates of the Point.
Examples
========
>>> from sympy import Point2D
>>> p = Point2D(0, 1)
>>> p.coordinates
(0, 1)
"""
return self.args
@property
def x(self):
"""
Returns the X coordinate of the Point.
Examples
========
>>> from sympy import Point2D
>>> p = Point2D(0, 1)
>>> p.x
0
"""
return self.args[0]
@property
def y(self):
"""
Returns the Y coordinate of the Point.
Examples
========
>>> from sympy import Point2D
>>> p = Point2D(0, 1)
>>> p.y
1
"""
return self.args[1]
class Point3D(Point):
"""A point in a 3-dimensional Euclidean space.
Parameters
==========
coords : sequence of 3 coordinate values.
Attributes
==========
x
y
z
length
Raises
======
TypeError
When trying to add or subtract points with different dimensions.
When `intersection` is called with object other than a Point.
Examples
========
>>> from sympy import Point3D
>>> from sympy.abc import x
>>> Point3D(1, 2, 3)
Point3D(1, 2, 3)
>>> Point3D([1, 2, 3])
Point3D(1, 2, 3)
>>> Point3D(0, x, 3)
Point3D(0, x, 3)
Floats are automatically converted to Rational unless the
evaluate flag is False:
>>> Point3D(0.5, 0.25, 2)
Point3D(1/2, 1/4, 2)
>>> Point3D(0.5, 0.25, 3, evaluate=False)
Point3D(0.5, 0.25, 3)
"""
_ambient_dimension = 3
def __new__(cls, *args, _nocheck=False, **kwargs):
if not _nocheck:
kwargs['dim'] = 3
args = Point(*args, **kwargs)
return GeometryEntity.__new__(cls, *args)
def __contains__(self, item):
return item == self
@staticmethod
def are_collinear(*points):
"""Is a sequence of points collinear?
Test whether or not a set of points are collinear. Returns True if
the set of points are collinear, or False otherwise.
Parameters
==========
points : sequence of Point
Returns
=======
are_collinear : boolean
See Also
========
sympy.geometry.line.Line3D
Examples
========
>>> from sympy import Point3D
>>> from sympy.abc import x
>>> p1, p2 = Point3D(0, 0, 0), Point3D(1, 1, 1)
>>> p3, p4, p5 = Point3D(2, 2, 2), Point3D(x, x, x), Point3D(1, 2, 6)
>>> Point3D.are_collinear(p1, p2, p3, p4)
True
>>> Point3D.are_collinear(p1, p2, p3, p5)
False
"""
return Point.is_collinear(*points)
def direction_cosine(self, point):
"""
Gives the direction cosine between 2 points
Parameters
==========
p : Point3D
Returns
=======
list
Examples
========
>>> from sympy import Point3D
>>> p1 = Point3D(1, 2, 3)
>>> p1.direction_cosine(Point3D(2, 3, 5))
[sqrt(6)/6, sqrt(6)/6, sqrt(6)/3]
"""
a = self.direction_ratio(point)
b = sqrt(Add(*(i**2 for i in a)))
return [(point.x - self.x) / b,(point.y - self.y) / b,
(point.z - self.z) / b]
def direction_ratio(self, point):
"""
Gives the direction ratio between 2 points
Parameters
==========
p : Point3D
Returns
=======
list
Examples
========
>>> from sympy import Point3D
>>> p1 = Point3D(1, 2, 3)
>>> p1.direction_ratio(Point3D(2, 3, 5))
[1, 1, 2]
"""
return [(point.x - self.x),(point.y - self.y),(point.z - self.z)]
def intersection(self, other):
"""The intersection between this point and another GeometryEntity.
Parameters
==========
other : GeometryEntity or sequence of coordinates
Returns
=======
intersection : list of Points
Notes
=====
The return value will either be an empty list if there is no
intersection, otherwise it will contain this point.
Examples
========
>>> from sympy import Point3D
>>> p1, p2, p3 = Point3D(0, 0, 0), Point3D(1, 1, 1), Point3D(0, 0, 0)
>>> p1.intersection(p2)
[]
>>> p1.intersection(p3)
[Point3D(0, 0, 0)]
"""
if not isinstance(other, GeometryEntity):
other = Point(other, dim=3)
if isinstance(other, Point3D):
if self == other:
return [self]
return []
return other.intersection(self)
def scale(self, x=1, y=1, z=1, pt=None):
"""Scale the coordinates of the Point by multiplying by
``x`` and ``y`` after subtracting ``pt`` -- default is (0, 0) --
and then adding ``pt`` back again (i.e. ``pt`` is the point of
reference for the scaling).
See Also
========
translate
Examples
========
>>> from sympy import Point3D
>>> t = Point3D(1, 1, 1)
>>> t.scale(2)
Point3D(2, 1, 1)
>>> t.scale(2, 2)
Point3D(2, 2, 1)
"""
if pt:
pt = Point3D(pt)
return self.translate(*(-pt).args).scale(x, y, z).translate(*pt.args)
return Point3D(self.x*x, self.y*y, self.z*z)
def transform(self, matrix):
"""Return the point after applying the transformation described
by the 4x4 Matrix, ``matrix``.
See Also
========
sympy.geometry.point.Point3D.scale
sympy.geometry.point.Point3D.translate
"""
if not (matrix.is_Matrix and matrix.shape == (4, 4)):
raise ValueError("matrix must be a 4x4 matrix")
from sympy.matrices.expressions import Transpose
x, y, z = self.args
m = Transpose(matrix)
return Point3D(*(Matrix(1, 4, [x, y, z, 1])*m).tolist()[0][:3])
def translate(self, x=0, y=0, z=0):
"""Shift the Point by adding x and y to the coordinates of the Point.
See Also
========
scale
Examples
========
>>> from sympy import Point3D
>>> t = Point3D(0, 1, 1)
>>> t.translate(2)
Point3D(2, 1, 1)
>>> t.translate(2, 2)
Point3D(2, 3, 1)
>>> t + Point3D(2, 2, 2)
Point3D(2, 3, 3)
"""
return Point3D(self.x + x, self.y + y, self.z + z)
@property
def coordinates(self):
"""
Returns the three coordinates of the Point.
Examples
========
>>> from sympy import Point3D
>>> p = Point3D(0, 1, 2)
>>> p.coordinates
(0, 1, 2)
"""
return self.args
@property
def x(self):
"""
Returns the X coordinate of the Point.
Examples
========
>>> from sympy import Point3D
>>> p = Point3D(0, 1, 3)
>>> p.x
0
"""
return self.args[0]
@property
def y(self):
"""
Returns the Y coordinate of the Point.
Examples
========
>>> from sympy import Point3D
>>> p = Point3D(0, 1, 2)
>>> p.y
1
"""
return self.args[1]
@property
def z(self):
"""
Returns the Z coordinate of the Point.
Examples
========
>>> from sympy import Point3D
>>> p = Point3D(0, 1, 1)
>>> p.z
1
"""
return self.args[2]
|
e179362eaf7786bf2270d76a591b2d8b624a5d5549d6bcf5fd494d2e819073b7 | """Line-like geometrical entities.
Contains
========
LinearEntity
Line
Ray
Segment
LinearEntity2D
Line2D
Ray2D
Segment2D
LinearEntity3D
Line3D
Ray3D
Segment3D
"""
from sympy import Expr
from sympy.core import S, sympify
from sympy.core.compatibility import ordered
from sympy.core.containers import Tuple
from sympy.core.decorators import deprecated
from sympy.core.numbers import Rational, oo
from sympy.core.relational import Eq
from sympy.core.symbol import _symbol, Dummy
from sympy.functions.elementary.piecewise import Piecewise
from sympy.functions.elementary.trigonometric import (_pi_coeff as pi_coeff, acos, tan, atan2)
from sympy.geometry.exceptions import GeometryError
from sympy.geometry.util import intersection
from sympy.logic.boolalg import And
from sympy.matrices import Matrix
from sympy.sets import Intersection
from sympy.simplify.simplify import simplify
from sympy.solvers.solveset import linear_coeffs
from sympy.utilities.exceptions import SymPyDeprecationWarning
from sympy.utilities.misc import Undecidable, filldedent
from .entity import GeometryEntity, GeometrySet
from .point import Point, Point3D
class LinearEntity(GeometrySet):
"""A base class for all linear entities (Line, Ray and Segment)
in n-dimensional Euclidean space.
Attributes
==========
ambient_dimension
direction
length
p1
p2
points
Notes
=====
This is an abstract class and is not meant to be instantiated.
See Also
========
sympy.geometry.entity.GeometryEntity
"""
def __new__(cls, p1, p2=None, **kwargs):
p1, p2 = Point._normalize_dimension(p1, p2)
if p1 == p2:
# sometimes we return a single point if we are not given two unique
# points. This is done in the specific subclass
raise ValueError(
"%s.__new__ requires two unique Points." % cls.__name__)
if len(p1) != len(p2):
raise ValueError(
"%s.__new__ requires two Points of equal dimension." % cls.__name__)
return GeometryEntity.__new__(cls, p1, p2, **kwargs)
def __contains__(self, other):
"""Return a definitive answer or else raise an error if it cannot
be determined that other is on the boundaries of self."""
result = self.contains(other)
if result is not None:
return result
else:
raise Undecidable(
"can't decide whether '%s' contains '%s'" % (self, other))
def _span_test(self, other):
"""Test whether the point `other` lies in the positive span of `self`.
A point x is 'in front' of a point y if x.dot(y) >= 0. Return
-1 if `other` is behind `self.p1`, 0 if `other` is `self.p1` and
and 1 if `other` is in front of `self.p1`."""
if self.p1 == other:
return 0
rel_pos = other - self.p1
d = self.direction
if d.dot(rel_pos) > 0:
return 1
return -1
@property
def ambient_dimension(self):
"""A property method that returns the dimension of LinearEntity
object.
Parameters
==========
p1 : LinearEntity
Returns
=======
dimension : integer
Examples
========
>>> from sympy import Point, Line
>>> p1, p2 = Point(0, 0), Point(1, 1)
>>> l1 = Line(p1, p2)
>>> l1.ambient_dimension
2
>>> from sympy import Point, Line
>>> p1, p2 = Point(0, 0, 0), Point(1, 1, 1)
>>> l1 = Line(p1, p2)
>>> l1.ambient_dimension
3
"""
return len(self.p1)
def angle_between(l1, l2):
"""Return the non-reflex angle formed by rays emanating from
the origin with directions the same as the direction vectors
of the linear entities.
Parameters
==========
l1 : LinearEntity
l2 : LinearEntity
Returns
=======
angle : angle in radians
Notes
=====
From the dot product of vectors v1 and v2 it is known that:
``dot(v1, v2) = |v1|*|v2|*cos(A)``
where A is the angle formed between the two vectors. We can
get the directional vectors of the two lines and readily
find the angle between the two using the above formula.
See Also
========
is_perpendicular, Ray2D.closing_angle
Examples
========
>>> from sympy import Line
>>> e = Line((0, 0), (1, 0))
>>> ne = Line((0, 0), (1, 1))
>>> sw = Line((1, 1), (0, 0))
>>> ne.angle_between(e)
pi/4
>>> sw.angle_between(e)
3*pi/4
To obtain the non-obtuse angle at the intersection of lines, use
the ``smallest_angle_between`` method:
>>> sw.smallest_angle_between(e)
pi/4
>>> from sympy import Point3D, Line3D
>>> p1, p2, p3 = Point3D(0, 0, 0), Point3D(1, 1, 1), Point3D(-1, 2, 0)
>>> l1, l2 = Line3D(p1, p2), Line3D(p2, p3)
>>> l1.angle_between(l2)
acos(-sqrt(2)/3)
>>> l1.smallest_angle_between(l2)
acos(sqrt(2)/3)
"""
if not isinstance(l1, LinearEntity) and not isinstance(l2, LinearEntity):
raise TypeError('Must pass only LinearEntity objects')
v1, v2 = l1.direction, l2.direction
return acos(v1.dot(v2)/(abs(v1)*abs(v2)))
def smallest_angle_between(l1, l2):
"""Return the smallest angle formed at the intersection of the
lines containing the linear entities.
Parameters
==========
l1 : LinearEntity
l2 : LinearEntity
Returns
=======
angle : angle in radians
See Also
========
angle_between, is_perpendicular, Ray2D.closing_angle
Examples
========
>>> from sympy import Point, Line
>>> p1, p2, p3 = Point(0, 0), Point(0, 4), Point(2, -2)
>>> l1, l2 = Line(p1, p2), Line(p1, p3)
>>> l1.smallest_angle_between(l2)
pi/4
See Also
========
angle_between, Ray2D.closing_angle
"""
if not isinstance(l1, LinearEntity) and not isinstance(l2, LinearEntity):
raise TypeError('Must pass only LinearEntity objects')
v1, v2 = l1.direction, l2.direction
return acos(abs(v1.dot(v2))/(abs(v1)*abs(v2)))
def arbitrary_point(self, parameter='t'):
"""A parameterized point on the Line.
Parameters
==========
parameter : str, optional
The name of the parameter which will be used for the parametric
point. The default value is 't'. When this parameter is 0, the
first point used to define the line will be returned, and when
it is 1 the second point will be returned.
Returns
=======
point : Point
Raises
======
ValueError
When ``parameter`` already appears in the Line's definition.
See Also
========
sympy.geometry.point.Point
Examples
========
>>> from sympy import Point, Line
>>> p1, p2 = Point(1, 0), Point(5, 3)
>>> l1 = Line(p1, p2)
>>> l1.arbitrary_point()
Point2D(4*t + 1, 3*t)
>>> from sympy import Point3D, Line3D
>>> p1, p2 = Point3D(1, 0, 0), Point3D(5, 3, 1)
>>> l1 = Line3D(p1, p2)
>>> l1.arbitrary_point()
Point3D(4*t + 1, 3*t, t)
"""
t = _symbol(parameter, real=True)
if t.name in (f.name for f in self.free_symbols):
raise ValueError(filldedent('''
Symbol %s already appears in object
and cannot be used as a parameter.
''' % t.name))
# multiply on the right so the variable gets
# combined with the coordinates of the point
return self.p1 + (self.p2 - self.p1)*t
@staticmethod
def are_concurrent(*lines):
"""Is a sequence of linear entities concurrent?
Two or more linear entities are concurrent if they all
intersect at a single point.
Parameters
==========
lines : a sequence of linear entities.
Returns
=======
True : if the set of linear entities intersect in one point
False : otherwise.
See Also
========
sympy.geometry.util.intersection
Examples
========
>>> from sympy import Point, Line
>>> p1, p2 = Point(0, 0), Point(3, 5)
>>> p3, p4 = Point(-2, -2), Point(0, 2)
>>> l1, l2, l3 = Line(p1, p2), Line(p1, p3), Line(p1, p4)
>>> Line.are_concurrent(l1, l2, l3)
True
>>> l4 = Line(p2, p3)
>>> Line.are_concurrent(l2, l3, l4)
False
>>> from sympy import Point3D, Line3D
>>> p1, p2 = Point3D(0, 0, 0), Point3D(3, 5, 2)
>>> p3, p4 = Point3D(-2, -2, -2), Point3D(0, 2, 1)
>>> l1, l2, l3 = Line3D(p1, p2), Line3D(p1, p3), Line3D(p1, p4)
>>> Line3D.are_concurrent(l1, l2, l3)
True
>>> l4 = Line3D(p2, p3)
>>> Line3D.are_concurrent(l2, l3, l4)
False
"""
common_points = Intersection(*lines)
if common_points.is_FiniteSet and len(common_points) == 1:
return True
return False
def contains(self, other):
"""Subclasses should implement this method and should return
True if other is on the boundaries of self;
False if not on the boundaries of self;
None if a determination cannot be made."""
raise NotImplementedError()
@property
def direction(self):
"""The direction vector of the LinearEntity.
Returns
=======
p : a Point; the ray from the origin to this point is the
direction of `self`
Examples
========
>>> from sympy.geometry import Line
>>> a, b = (1, 1), (1, 3)
>>> Line(a, b).direction
Point2D(0, 2)
>>> Line(b, a).direction
Point2D(0, -2)
This can be reported so the distance from the origin is 1:
>>> Line(b, a).direction.unit
Point2D(0, -1)
See Also
========
sympy.geometry.point.Point.unit
"""
return self.p2 - self.p1
def intersection(self, other):
"""The intersection with another geometrical entity.
Parameters
==========
o : Point or LinearEntity
Returns
=======
intersection : list of geometrical entities
See Also
========
sympy.geometry.point.Point
Examples
========
>>> from sympy import Point, Line, Segment
>>> p1, p2, p3 = Point(0, 0), Point(1, 1), Point(7, 7)
>>> l1 = Line(p1, p2)
>>> l1.intersection(p3)
[Point2D(7, 7)]
>>> p4, p5 = Point(5, 0), Point(0, 3)
>>> l2 = Line(p4, p5)
>>> l1.intersection(l2)
[Point2D(15/8, 15/8)]
>>> p6, p7 = Point(0, 5), Point(2, 6)
>>> s1 = Segment(p6, p7)
>>> l1.intersection(s1)
[]
>>> from sympy import Point3D, Line3D, Segment3D
>>> p1, p2, p3 = Point3D(0, 0, 0), Point3D(1, 1, 1), Point3D(7, 7, 7)
>>> l1 = Line3D(p1, p2)
>>> l1.intersection(p3)
[Point3D(7, 7, 7)]
>>> l1 = Line3D(Point3D(4,19,12), Point3D(5,25,17))
>>> l2 = Line3D(Point3D(-3, -15, -19), direction_ratio=[2,8,8])
>>> l1.intersection(l2)
[Point3D(1, 1, -3)]
>>> p6, p7 = Point3D(0, 5, 2), Point3D(2, 6, 3)
>>> s1 = Segment3D(p6, p7)
>>> l1.intersection(s1)
[]
"""
def intersect_parallel_rays(ray1, ray2):
if ray1.direction.dot(ray2.direction) > 0:
# rays point in the same direction
# so return the one that is "in front"
return [ray2] if ray1._span_test(ray2.p1) >= 0 else [ray1]
else:
# rays point in opposite directions
st = ray1._span_test(ray2.p1)
if st < 0:
return []
elif st == 0:
return [ray2.p1]
return [Segment(ray1.p1, ray2.p1)]
def intersect_parallel_ray_and_segment(ray, seg):
st1, st2 = ray._span_test(seg.p1), ray._span_test(seg.p2)
if st1 < 0 and st2 < 0:
return []
elif st1 >= 0 and st2 >= 0:
return [seg]
elif st1 >= 0: # st2 < 0:
return [Segment(ray.p1, seg.p1)]
else: # st1 < 0 and st2 >= 0:
return [Segment(ray.p1, seg.p2)]
def intersect_parallel_segments(seg1, seg2):
if seg1.contains(seg2):
return [seg2]
if seg2.contains(seg1):
return [seg1]
# direct the segments so they're oriented the same way
if seg1.direction.dot(seg2.direction) < 0:
seg2 = Segment(seg2.p2, seg2.p1)
# order the segments so seg1 is "behind" seg2
if seg1._span_test(seg2.p1) < 0:
seg1, seg2 = seg2, seg1
if seg2._span_test(seg1.p2) < 0:
return []
return [Segment(seg2.p1, seg1.p2)]
if not isinstance(other, GeometryEntity):
other = Point(other, dim=self.ambient_dimension)
if other.is_Point:
if self.contains(other):
return [other]
else:
return []
elif isinstance(other, LinearEntity):
# break into cases based on whether
# the lines are parallel, non-parallel intersecting, or skew
pts = Point._normalize_dimension(self.p1, self.p2, other.p1, other.p2)
rank = Point.affine_rank(*pts)
if rank == 1:
# we're collinear
if isinstance(self, Line):
return [other]
if isinstance(other, Line):
return [self]
if isinstance(self, Ray) and isinstance(other, Ray):
return intersect_parallel_rays(self, other)
if isinstance(self, Ray) and isinstance(other, Segment):
return intersect_parallel_ray_and_segment(self, other)
if isinstance(self, Segment) and isinstance(other, Ray):
return intersect_parallel_ray_and_segment(other, self)
if isinstance(self, Segment) and isinstance(other, Segment):
return intersect_parallel_segments(self, other)
elif rank == 2:
# we're in the same plane
l1 = Line(*pts[:2])
l2 = Line(*pts[2:])
# check to see if we're parallel. If we are, we can't
# be intersecting, since the collinear case was already
# handled
if l1.direction.is_scalar_multiple(l2.direction):
return []
# find the intersection as if everything were lines
# by solving the equation t*d + p1 == s*d' + p1'
m = Matrix([l1.direction, -l2.direction]).transpose()
v = Matrix([l2.p1 - l1.p1]).transpose()
# we cannot use m.solve(v) because that only works for square matrices
m_rref, pivots = m.col_insert(2, v).rref(simplify=True)
# rank == 2 ensures we have 2 pivots, but let's check anyway
if len(pivots) != 2:
raise GeometryError("Failed when solving Mx=b when M={} and b={}".format(m, v))
coeff = m_rref[0, 2]
line_intersection = l1.direction*coeff + self.p1
# if we're both lines, we can skip a containment check
if isinstance(self, Line) and isinstance(other, Line):
return [line_intersection]
if ((isinstance(self, Line) or
self.contains(line_intersection)) and
other.contains(line_intersection)):
return [line_intersection]
return []
else:
# we're skew
return []
return other.intersection(self)
def is_parallel(l1, l2):
"""Are two linear entities parallel?
Parameters
==========
l1 : LinearEntity
l2 : LinearEntity
Returns
=======
True : if l1 and l2 are parallel,
False : otherwise.
See Also
========
coefficients
Examples
========
>>> from sympy import Point, Line
>>> p1, p2 = Point(0, 0), Point(1, 1)
>>> p3, p4 = Point(3, 4), Point(6, 7)
>>> l1, l2 = Line(p1, p2), Line(p3, p4)
>>> Line.is_parallel(l1, l2)
True
>>> p5 = Point(6, 6)
>>> l3 = Line(p3, p5)
>>> Line.is_parallel(l1, l3)
False
>>> from sympy import Point3D, Line3D
>>> p1, p2 = Point3D(0, 0, 0), Point3D(3, 4, 5)
>>> p3, p4 = Point3D(2, 1, 1), Point3D(8, 9, 11)
>>> l1, l2 = Line3D(p1, p2), Line3D(p3, p4)
>>> Line3D.is_parallel(l1, l2)
True
>>> p5 = Point3D(6, 6, 6)
>>> l3 = Line3D(p3, p5)
>>> Line3D.is_parallel(l1, l3)
False
"""
if not isinstance(l1, LinearEntity) and not isinstance(l2, LinearEntity):
raise TypeError('Must pass only LinearEntity objects')
return l1.direction.is_scalar_multiple(l2.direction)
def is_perpendicular(l1, l2):
"""Are two linear entities perpendicular?
Parameters
==========
l1 : LinearEntity
l2 : LinearEntity
Returns
=======
True : if l1 and l2 are perpendicular,
False : otherwise.
See Also
========
coefficients
Examples
========
>>> from sympy import Point, Line
>>> p1, p2, p3 = Point(0, 0), Point(1, 1), Point(-1, 1)
>>> l1, l2 = Line(p1, p2), Line(p1, p3)
>>> l1.is_perpendicular(l2)
True
>>> p4 = Point(5, 3)
>>> l3 = Line(p1, p4)
>>> l1.is_perpendicular(l3)
False
>>> from sympy import Point3D, Line3D
>>> p1, p2, p3 = Point3D(0, 0, 0), Point3D(1, 1, 1), Point3D(-1, 2, 0)
>>> l1, l2 = Line3D(p1, p2), Line3D(p2, p3)
>>> l1.is_perpendicular(l2)
False
>>> p4 = Point3D(5, 3, 7)
>>> l3 = Line3D(p1, p4)
>>> l1.is_perpendicular(l3)
False
"""
if not isinstance(l1, LinearEntity) and not isinstance(l2, LinearEntity):
raise TypeError('Must pass only LinearEntity objects')
return S.Zero.equals(l1.direction.dot(l2.direction))
def is_similar(self, other):
"""
Return True if self and other are contained in the same line.
Examples
========
>>> from sympy import Point, Line
>>> p1, p2, p3 = Point(0, 1), Point(3, 4), Point(2, 3)
>>> l1 = Line(p1, p2)
>>> l2 = Line(p1, p3)
>>> l1.is_similar(l2)
True
"""
l = Line(self.p1, self.p2)
return l.contains(other)
@property
def length(self):
"""
The length of the line.
Examples
========
>>> from sympy import Point, Line
>>> p1, p2 = Point(0, 0), Point(3, 5)
>>> l1 = Line(p1, p2)
>>> l1.length
oo
"""
return S.Infinity
@property
def p1(self):
"""The first defining point of a linear entity.
See Also
========
sympy.geometry.point.Point
Examples
========
>>> from sympy import Point, Line
>>> p1, p2 = Point(0, 0), Point(5, 3)
>>> l = Line(p1, p2)
>>> l.p1
Point2D(0, 0)
"""
return self.args[0]
@property
def p2(self):
"""The second defining point of a linear entity.
See Also
========
sympy.geometry.point.Point
Examples
========
>>> from sympy import Point, Line
>>> p1, p2 = Point(0, 0), Point(5, 3)
>>> l = Line(p1, p2)
>>> l.p2
Point2D(5, 3)
"""
return self.args[1]
def parallel_line(self, p):
"""Create a new Line parallel to this linear entity which passes
through the point `p`.
Parameters
==========
p : Point
Returns
=======
line : Line
See Also
========
is_parallel
Examples
========
>>> from sympy import Point, Line
>>> p1, p2, p3 = Point(0, 0), Point(2, 3), Point(-2, 2)
>>> l1 = Line(p1, p2)
>>> l2 = l1.parallel_line(p3)
>>> p3 in l2
True
>>> l1.is_parallel(l2)
True
>>> from sympy import Point3D, Line3D
>>> p1, p2, p3 = Point3D(0, 0, 0), Point3D(2, 3, 4), Point3D(-2, 2, 0)
>>> l1 = Line3D(p1, p2)
>>> l2 = l1.parallel_line(p3)
>>> p3 in l2
True
>>> l1.is_parallel(l2)
True
"""
p = Point(p, dim=self.ambient_dimension)
return Line(p, p + self.direction)
def perpendicular_line(self, p):
"""Create a new Line perpendicular to this linear entity which passes
through the point `p`.
Parameters
==========
p : Point
Returns
=======
line : Line
See Also
========
sympy.geometry.line.LinearEntity.is_perpendicular, perpendicular_segment
Examples
========
>>> from sympy import Point, Line
>>> p1, p2, p3 = Point(0, 0), Point(2, 3), Point(-2, 2)
>>> l1 = Line(p1, p2)
>>> l2 = l1.perpendicular_line(p3)
>>> p3 in l2
True
>>> l1.is_perpendicular(l2)
True
>>> from sympy import Point3D, Line3D
>>> p1, p2, p3 = Point3D(0, 0, 0), Point3D(2, 3, 4), Point3D(-2, 2, 0)
>>> l1 = Line3D(p1, p2)
>>> l2 = l1.perpendicular_line(p3)
>>> p3 in l2
True
>>> l1.is_perpendicular(l2)
True
"""
p = Point(p, dim=self.ambient_dimension)
if p in self:
p = p + self.direction.orthogonal_direction
return Line(p, self.projection(p))
def perpendicular_segment(self, p):
"""Create a perpendicular line segment from `p` to this line.
The enpoints of the segment are ``p`` and the closest point in
the line containing self. (If self is not a line, the point might
not be in self.)
Parameters
==========
p : Point
Returns
=======
segment : Segment
Notes
=====
Returns `p` itself if `p` is on this linear entity.
See Also
========
perpendicular_line
Examples
========
>>> from sympy import Point, Line
>>> p1, p2, p3 = Point(0, 0), Point(1, 1), Point(0, 2)
>>> l1 = Line(p1, p2)
>>> s1 = l1.perpendicular_segment(p3)
>>> l1.is_perpendicular(s1)
True
>>> p3 in s1
True
>>> l1.perpendicular_segment(Point(4, 0))
Segment2D(Point2D(4, 0), Point2D(2, 2))
>>> from sympy import Point3D, Line3D
>>> p1, p2, p3 = Point3D(0, 0, 0), Point3D(1, 1, 1), Point3D(0, 2, 0)
>>> l1 = Line3D(p1, p2)
>>> s1 = l1.perpendicular_segment(p3)
>>> l1.is_perpendicular(s1)
True
>>> p3 in s1
True
>>> l1.perpendicular_segment(Point3D(4, 0, 0))
Segment3D(Point3D(4, 0, 0), Point3D(4/3, 4/3, 4/3))
"""
p = Point(p, dim=self.ambient_dimension)
if p in self:
return p
l = self.perpendicular_line(p)
# The intersection should be unique, so unpack the singleton
p2, = Intersection(Line(self.p1, self.p2), l)
return Segment(p, p2)
@property
def points(self):
"""The two points used to define this linear entity.
Returns
=======
points : tuple of Points
See Also
========
sympy.geometry.point.Point
Examples
========
>>> from sympy import Point, Line
>>> p1, p2 = Point(0, 0), Point(5, 11)
>>> l1 = Line(p1, p2)
>>> l1.points
(Point2D(0, 0), Point2D(5, 11))
"""
return (self.p1, self.p2)
def projection(self, other):
"""Project a point, line, ray, or segment onto this linear entity.
Parameters
==========
other : Point or LinearEntity (Line, Ray, Segment)
Returns
=======
projection : Point or LinearEntity (Line, Ray, Segment)
The return type matches the type of the parameter ``other``.
Raises
======
GeometryError
When method is unable to perform projection.
Notes
=====
A projection involves taking the two points that define
the linear entity and projecting those points onto a
Line and then reforming the linear entity using these
projections.
A point P is projected onto a line L by finding the point
on L that is closest to P. This point is the intersection
of L and the line perpendicular to L that passes through P.
See Also
========
sympy.geometry.point.Point, perpendicular_line
Examples
========
>>> from sympy import Point, Line, Segment, Rational
>>> p1, p2, p3 = Point(0, 0), Point(1, 1), Point(Rational(1, 2), 0)
>>> l1 = Line(p1, p2)
>>> l1.projection(p3)
Point2D(1/4, 1/4)
>>> p4, p5 = Point(10, 0), Point(12, 1)
>>> s1 = Segment(p4, p5)
>>> l1.projection(s1)
Segment2D(Point2D(5, 5), Point2D(13/2, 13/2))
>>> p1, p2, p3 = Point(0, 0, 1), Point(1, 1, 2), Point(2, 0, 1)
>>> l1 = Line(p1, p2)
>>> l1.projection(p3)
Point3D(2/3, 2/3, 5/3)
>>> p4, p5 = Point(10, 0, 1), Point(12, 1, 3)
>>> s1 = Segment(p4, p5)
>>> l1.projection(s1)
Segment3D(Point3D(10/3, 10/3, 13/3), Point3D(5, 5, 6))
"""
if not isinstance(other, GeometryEntity):
other = Point(other, dim=self.ambient_dimension)
def proj_point(p):
return Point.project(p - self.p1, self.direction) + self.p1
if isinstance(other, Point):
return proj_point(other)
elif isinstance(other, LinearEntity):
p1, p2 = proj_point(other.p1), proj_point(other.p2)
# test to see if we're degenerate
if p1 == p2:
return p1
projected = other.__class__(p1, p2)
projected = Intersection(self, projected)
# if we happen to have intersected in only a point, return that
if projected.is_FiniteSet and len(projected) == 1:
# projected is a set of size 1, so unpack it in `a`
a, = projected
return a
# order args so projection is in the same direction as self
if self.direction.dot(projected.direction) < 0:
p1, p2 = projected.args
projected = projected.func(p2, p1)
return projected
raise GeometryError(
"Do not know how to project %s onto %s" % (other, self))
def random_point(self, seed=None):
"""A random point on a LinearEntity.
Returns
=======
point : Point
See Also
========
sympy.geometry.point.Point
Examples
========
>>> from sympy import Point, Line, Ray, Segment
>>> p1, p2 = Point(0, 0), Point(5, 3)
>>> line = Line(p1, p2)
>>> r = line.random_point(seed=42) # seed value is optional
>>> r.n(3)
Point2D(-0.72, -0.432)
>>> r in line
True
>>> Ray(p1, p2).random_point(seed=42).n(3)
Point2D(0.72, 0.432)
>>> Segment(p1, p2).random_point(seed=42).n(3)
Point2D(3.2, 1.92)
"""
import random
if seed is not None:
rng = random.Random(seed)
else:
rng = random
t = Dummy()
pt = self.arbitrary_point(t)
if isinstance(self, Ray):
v = abs(rng.gauss(0, 1))
elif isinstance(self, Segment):
v = rng.random()
elif isinstance(self, Line):
v = rng.gauss(0, 1)
else:
raise NotImplementedError('unhandled line type')
return pt.subs(t, Rational(v))
def bisectors(self, other):
"""Returns the perpendicular lines which pass through the intersections
of self and other that are in the same plane.
Parameters
==========
line : Line3D
Returns
=======
list: two Line instances
Examples
========
>>> from sympy.geometry import Point3D, Line3D
>>> r1 = Line3D(Point3D(0, 0, 0), Point3D(1, 0, 0))
>>> r2 = Line3D(Point3D(0, 0, 0), Point3D(0, 1, 0))
>>> r1.bisectors(r2)
[Line3D(Point3D(0, 0, 0), Point3D(1, 1, 0)), Line3D(Point3D(0, 0, 0), Point3D(1, -1, 0))]
"""
if not isinstance(other, LinearEntity):
raise GeometryError("Expecting LinearEntity, not %s" % other)
l1, l2 = self, other
# make sure dimensions match or else a warning will rise from
# intersection calculation
if l1.p1.ambient_dimension != l2.p1.ambient_dimension:
if isinstance(l1, Line2D):
l1, l2 = l2, l1
_, p1 = Point._normalize_dimension(l1.p1, l2.p1, on_morph='ignore')
_, p2 = Point._normalize_dimension(l1.p2, l2.p2, on_morph='ignore')
l2 = Line(p1, p2)
point = intersection(l1, l2)
# Three cases: Lines may intersect in a point, may be equal or may not intersect.
if not point:
raise GeometryError("The lines do not intersect")
else:
pt = point[0]
if isinstance(pt, Line):
# Intersection is a line because both lines are coincident
return [self]
d1 = l1.direction.unit
d2 = l2.direction.unit
bis1 = Line(pt, pt + d1 + d2)
bis2 = Line(pt, pt + d1 - d2)
return [bis1, bis2]
class Line(LinearEntity):
"""An infinite line in space.
A 2D line is declared with two distinct points, point and slope, or
an equation. A 3D line may be defined with a point and a direction ratio.
Parameters
==========
p1 : Point
p2 : Point
slope : sympy expression
direction_ratio : list
equation : equation of a line
Notes
=====
`Line` will automatically subclass to `Line2D` or `Line3D` based
on the dimension of `p1`. The `slope` argument is only relevant
for `Line2D` and the `direction_ratio` argument is only relevant
for `Line3D`.
See Also
========
sympy.geometry.point.Point
sympy.geometry.line.Line2D
sympy.geometry.line.Line3D
Examples
========
>>> from sympy import Point, Eq
>>> from sympy.geometry import Line, Segment
>>> from sympy.abc import x, y, a, b
>>> L = Line(Point(2,3), Point(3,5))
>>> L
Line2D(Point2D(2, 3), Point2D(3, 5))
>>> L.points
(Point2D(2, 3), Point2D(3, 5))
>>> L.equation()
-2*x + y + 1
>>> L.coefficients
(-2, 1, 1)
Instantiate with keyword ``slope``:
>>> Line(Point(0, 0), slope=0)
Line2D(Point2D(0, 0), Point2D(1, 0))
Instantiate with another linear object
>>> s = Segment((0, 0), (0, 1))
>>> Line(s).equation()
x
The line corresponding to an equation in the for `ax + by + c = 0`,
can be entered:
>>> Line(3*x + y + 18)
Line2D(Point2D(0, -18), Point2D(1, -21))
If `x` or `y` has a different name, then they can be specified, too,
as a string (to match the name) or symbol:
>>> Line(Eq(3*a + b, -18), x='a', y=b)
Line2D(Point2D(0, -18), Point2D(1, -21))
"""
def __new__(cls, *args, **kwargs):
from sympy.geometry.util import find
if len(args) == 1 and isinstance(args[0], (Expr, Eq)):
x = kwargs.get('x', 'x')
y = kwargs.get('y', 'y')
equation = args[0]
if isinstance(equation, Eq):
equation = equation.lhs - equation.rhs
xin, yin = x, y
x = find(x, equation) or Dummy()
y = find(y, equation) or Dummy()
a, b, c = linear_coeffs(equation, x, y)
if b:
return Line((0, -c/b), slope=-a/b)
if a:
return Line((-c/a, 0), slope=oo)
raise ValueError('neither %s nor %s were found in the equation' % (xin, yin))
else:
if len(args) > 0:
p1 = args[0]
if len(args) > 1:
p2 = args[1]
else:
p2 = None
if isinstance(p1, LinearEntity):
if p2:
raise ValueError('If p1 is a LinearEntity, p2 must be None.')
dim = len(p1.p1)
else:
p1 = Point(p1)
dim = len(p1)
if p2 is not None or isinstance(p2, Point) and p2.ambient_dimension != dim:
p2 = Point(p2)
if dim == 2:
return Line2D(p1, p2, **kwargs)
elif dim == 3:
return Line3D(p1, p2, **kwargs)
return LinearEntity.__new__(cls, p1, p2, **kwargs)
def contains(self, other):
"""
Return True if `other` is on this Line, or False otherwise.
Examples
========
>>> from sympy import Line,Point
>>> p1, p2 = Point(0, 1), Point(3, 4)
>>> l = Line(p1, p2)
>>> l.contains(p1)
True
>>> l.contains((0, 1))
True
>>> l.contains((0, 0))
False
>>> a = (0, 0, 0)
>>> b = (1, 1, 1)
>>> c = (2, 2, 2)
>>> l1 = Line(a, b)
>>> l2 = Line(b, a)
>>> l1 == l2
False
>>> l1 in l2
True
"""
if not isinstance(other, GeometryEntity):
other = Point(other, dim=self.ambient_dimension)
if isinstance(other, Point):
return Point.is_collinear(other, self.p1, self.p2)
if isinstance(other, LinearEntity):
return Point.is_collinear(self.p1, self.p2, other.p1, other.p2)
return False
def distance(self, other):
"""
Finds the shortest distance between a line and a point.
Raises
======
NotImplementedError is raised if `other` is not a Point
Examples
========
>>> from sympy import Point, Line
>>> p1, p2 = Point(0, 0), Point(1, 1)
>>> s = Line(p1, p2)
>>> s.distance(Point(-1, 1))
sqrt(2)
>>> s.distance((-1, 2))
3*sqrt(2)/2
>>> p1, p2 = Point(0, 0, 0), Point(1, 1, 1)
>>> s = Line(p1, p2)
>>> s.distance(Point(-1, 1, 1))
2*sqrt(6)/3
>>> s.distance((-1, 1, 1))
2*sqrt(6)/3
"""
if not isinstance(other, GeometryEntity):
other = Point(other, dim=self.ambient_dimension)
if self.contains(other):
return S.Zero
return self.perpendicular_segment(other).length
@deprecated(useinstead="equals", issue=12860, deprecated_since_version="1.0")
def equal(self, other):
return self.equals(other)
def equals(self, other):
"""Returns True if self and other are the same mathematical entities"""
if not isinstance(other, Line):
return False
return Point.is_collinear(self.p1, other.p1, self.p2, other.p2)
def plot_interval(self, parameter='t'):
"""The plot interval for the default geometric plot of line. Gives
values that will produce a line that is +/- 5 units long (where a
unit is the distance between the two points that define the line).
Parameters
==========
parameter : str, optional
Default value is 't'.
Returns
=======
plot_interval : list (plot interval)
[parameter, lower_bound, upper_bound]
Examples
========
>>> from sympy import Point, Line
>>> p1, p2 = Point(0, 0), Point(5, 3)
>>> l1 = Line(p1, p2)
>>> l1.plot_interval()
[t, -5, 5]
"""
t = _symbol(parameter, real=True)
return [t, -5, 5]
class Ray(LinearEntity):
"""A Ray is a semi-line in the space with a source point and a direction.
Parameters
==========
p1 : Point
The source of the Ray
p2 : Point or radian value
This point determines the direction in which the Ray propagates.
If given as an angle it is interpreted in radians with the positive
direction being ccw.
Attributes
==========
source
See Also
========
sympy.geometry.line.Ray2D
sympy.geometry.line.Ray3D
sympy.geometry.point.Point
sympy.geometry.line.Line
Notes
=====
`Ray` will automatically subclass to `Ray2D` or `Ray3D` based on the
dimension of `p1`.
Examples
========
>>> from sympy import Point, pi
>>> from sympy.geometry import Ray
>>> r = Ray(Point(2, 3), Point(3, 5))
>>> r
Ray2D(Point2D(2, 3), Point2D(3, 5))
>>> r.points
(Point2D(2, 3), Point2D(3, 5))
>>> r.source
Point2D(2, 3)
>>> r.xdirection
oo
>>> r.ydirection
oo
>>> r.slope
2
>>> Ray(Point(0, 0), angle=pi/4).slope
1
"""
def __new__(cls, p1, p2=None, **kwargs):
p1 = Point(p1)
if p2 is not None:
p1, p2 = Point._normalize_dimension(p1, Point(p2))
dim = len(p1)
if dim == 2:
return Ray2D(p1, p2, **kwargs)
elif dim == 3:
return Ray3D(p1, p2, **kwargs)
return LinearEntity.__new__(cls, p1, p2, **kwargs)
def _svg(self, scale_factor=1., fill_color="#66cc99"):
"""Returns SVG path element for the LinearEntity.
Parameters
==========
scale_factor : float
Multiplication factor for the SVG stroke-width. Default is 1.
fill_color : str, optional
Hex string for fill color. Default is "#66cc99".
"""
from sympy.core.evalf import N
verts = (N(self.p1), N(self.p2))
coords = ["{},{}".format(p.x, p.y) for p in verts]
path = "M {} L {}".format(coords[0], " L ".join(coords[1:]))
return (
'<path fill-rule="evenodd" fill="{2}" stroke="#555555" '
'stroke-width="{0}" opacity="0.6" d="{1}" '
'marker-start="url(#markerCircle)" marker-end="url(#markerArrow)"/>'
).format(2.*scale_factor, path, fill_color)
def contains(self, other):
"""
Is other GeometryEntity contained in this Ray?
Examples
========
>>> from sympy import Ray,Point,Segment
>>> p1, p2 = Point(0, 0), Point(4, 4)
>>> r = Ray(p1, p2)
>>> r.contains(p1)
True
>>> r.contains((1, 1))
True
>>> r.contains((1, 3))
False
>>> s = Segment((1, 1), (2, 2))
>>> r.contains(s)
True
>>> s = Segment((1, 2), (2, 5))
>>> r.contains(s)
False
>>> r1 = Ray((2, 2), (3, 3))
>>> r.contains(r1)
True
>>> r1 = Ray((2, 2), (3, 5))
>>> r.contains(r1)
False
"""
if not isinstance(other, GeometryEntity):
other = Point(other, dim=self.ambient_dimension)
if isinstance(other, Point):
if Point.is_collinear(self.p1, self.p2, other):
# if we're in the direction of the ray, our
# direction vector dot the ray's direction vector
# should be non-negative
return bool((self.p2 - self.p1).dot(other - self.p1) >= S.Zero)
return False
elif isinstance(other, Ray):
if Point.is_collinear(self.p1, self.p2, other.p1, other.p2):
return bool((self.p2 - self.p1).dot(other.p2 - other.p1) > S.Zero)
return False
elif isinstance(other, Segment):
return other.p1 in self and other.p2 in self
# No other known entity can be contained in a Ray
return False
def distance(self, other):
"""
Finds the shortest distance between the ray and a point.
Raises
======
NotImplementedError is raised if `other` is not a Point
Examples
========
>>> from sympy import Point, Ray
>>> p1, p2 = Point(0, 0), Point(1, 1)
>>> s = Ray(p1, p2)
>>> s.distance(Point(-1, -1))
sqrt(2)
>>> s.distance((-1, 2))
3*sqrt(2)/2
>>> p1, p2 = Point(0, 0, 0), Point(1, 1, 2)
>>> s = Ray(p1, p2)
>>> s
Ray3D(Point3D(0, 0, 0), Point3D(1, 1, 2))
>>> s.distance(Point(-1, -1, 2))
4*sqrt(3)/3
>>> s.distance((-1, -1, 2))
4*sqrt(3)/3
"""
if not isinstance(other, GeometryEntity):
other = Point(other, dim=self.ambient_dimension)
if self.contains(other):
return S.Zero
proj = Line(self.p1, self.p2).projection(other)
if self.contains(proj):
return abs(other - proj)
else:
return abs(other - self.source)
def equals(self, other):
"""Returns True if self and other are the same mathematical entities"""
if not isinstance(other, Ray):
return False
return self.source == other.source and other.p2 in self
def plot_interval(self, parameter='t'):
"""The plot interval for the default geometric plot of the Ray. Gives
values that will produce a ray that is 10 units long (where a unit is
the distance between the two points that define the ray).
Parameters
==========
parameter : str, optional
Default value is 't'.
Returns
=======
plot_interval : list
[parameter, lower_bound, upper_bound]
Examples
========
>>> from sympy import Ray, pi
>>> r = Ray((0, 0), angle=pi/4)
>>> r.plot_interval()
[t, 0, 10]
"""
t = _symbol(parameter, real=True)
return [t, 0, 10]
@property
def source(self):
"""The point from which the ray emanates.
See Also
========
sympy.geometry.point.Point
Examples
========
>>> from sympy import Point, Ray
>>> p1, p2 = Point(0, 0), Point(4, 1)
>>> r1 = Ray(p1, p2)
>>> r1.source
Point2D(0, 0)
>>> p1, p2 = Point(0, 0, 0), Point(4, 1, 5)
>>> r1 = Ray(p2, p1)
>>> r1.source
Point3D(4, 1, 5)
"""
return self.p1
class Segment(LinearEntity):
"""A line segment in space.
Parameters
==========
p1 : Point
p2 : Point
Attributes
==========
length : number or sympy expression
midpoint : Point
See Also
========
sympy.geometry.line.Segment2D
sympy.geometry.line.Segment3D
sympy.geometry.point.Point
sympy.geometry.line.Line
Notes
=====
If 2D or 3D points are used to define `Segment`, it will
be automatically subclassed to `Segment2D` or `Segment3D`.
Examples
========
>>> from sympy import Point
>>> from sympy.geometry import Segment
>>> Segment((1, 0), (1, 1)) # tuples are interpreted as pts
Segment2D(Point2D(1, 0), Point2D(1, 1))
>>> s = Segment(Point(4, 3), Point(1, 1))
>>> s.points
(Point2D(4, 3), Point2D(1, 1))
>>> s.slope
2/3
>>> s.length
sqrt(13)
>>> s.midpoint
Point2D(5/2, 2)
>>> Segment((1, 0, 0), (1, 1, 1)) # tuples are interpreted as pts
Segment3D(Point3D(1, 0, 0), Point3D(1, 1, 1))
>>> s = Segment(Point(4, 3, 9), Point(1, 1, 7)); s
Segment3D(Point3D(4, 3, 9), Point3D(1, 1, 7))
>>> s.points
(Point3D(4, 3, 9), Point3D(1, 1, 7))
>>> s.length
sqrt(17)
>>> s.midpoint
Point3D(5/2, 2, 8)
"""
def __new__(cls, p1, p2, **kwargs):
p1, p2 = Point._normalize_dimension(Point(p1), Point(p2))
dim = len(p1)
if dim == 2:
return Segment2D(p1, p2, **kwargs)
elif dim == 3:
return Segment3D(p1, p2, **kwargs)
return LinearEntity.__new__(cls, p1, p2, **kwargs)
def contains(self, other):
"""
Is the other GeometryEntity contained within this Segment?
Examples
========
>>> from sympy import Point, Segment
>>> p1, p2 = Point(0, 1), Point(3, 4)
>>> s = Segment(p1, p2)
>>> s2 = Segment(p2, p1)
>>> s.contains(s2)
True
>>> from sympy import Point3D, Segment3D
>>> p1, p2 = Point3D(0, 1, 1), Point3D(3, 4, 5)
>>> s = Segment3D(p1, p2)
>>> s2 = Segment3D(p2, p1)
>>> s.contains(s2)
True
>>> s.contains((p1 + p2)/2)
True
"""
if not isinstance(other, GeometryEntity):
other = Point(other, dim=self.ambient_dimension)
if isinstance(other, Point):
if Point.is_collinear(other, self.p1, self.p2):
if isinstance(self, Segment2D):
# if it is collinear and is in the bounding box of the
# segment then it must be on the segment
vert = (1/self.slope).equals(0)
if vert is False:
isin = (self.p1.x - other.x)*(self.p2.x - other.x) <= 0
if isin in (True, False):
return isin
if vert is True:
isin = (self.p1.y - other.y)*(self.p2.y - other.y) <= 0
if isin in (True, False):
return isin
# use the triangle inequality
d1, d2 = other - self.p1, other - self.p2
d = self.p2 - self.p1
# without the call to simplify, sympy cannot tell that an expression
# like (a+b)*(a/2+b/2) is always non-negative. If it cannot be
# determined, raise an Undecidable error
try:
# the triangle inequality says that |d1|+|d2| >= |d| and is strict
# only if other lies in the line segment
return bool(simplify(Eq(abs(d1) + abs(d2) - abs(d), 0)))
except TypeError:
raise Undecidable("Cannot determine if {} is in {}".format(other, self))
if isinstance(other, Segment):
return other.p1 in self and other.p2 in self
return False
def equals(self, other):
"""Returns True if self and other are the same mathematical entities"""
return isinstance(other, self.func) and list(
ordered(self.args)) == list(ordered(other.args))
def distance(self, other):
"""
Finds the shortest distance between a line segment and a point.
Raises
======
NotImplementedError is raised if `other` is not a Point
Examples
========
>>> from sympy import Point, Segment
>>> p1, p2 = Point(0, 1), Point(3, 4)
>>> s = Segment(p1, p2)
>>> s.distance(Point(10, 15))
sqrt(170)
>>> s.distance((0, 12))
sqrt(73)
>>> from sympy import Point3D, Segment3D
>>> p1, p2 = Point3D(0, 0, 3), Point3D(1, 1, 4)
>>> s = Segment3D(p1, p2)
>>> s.distance(Point3D(10, 15, 12))
sqrt(341)
>>> s.distance((10, 15, 12))
sqrt(341)
"""
if not isinstance(other, GeometryEntity):
other = Point(other, dim=self.ambient_dimension)
if isinstance(other, Point):
vp1 = other - self.p1
vp2 = other - self.p2
dot_prod_sign_1 = self.direction.dot(vp1) >= 0
dot_prod_sign_2 = self.direction.dot(vp2) <= 0
if dot_prod_sign_1 and dot_prod_sign_2:
return Line(self.p1, self.p2).distance(other)
if dot_prod_sign_1 and not dot_prod_sign_2:
return abs(vp2)
if not dot_prod_sign_1 and dot_prod_sign_2:
return abs(vp1)
raise NotImplementedError()
@property
def length(self):
"""The length of the line segment.
See Also
========
sympy.geometry.point.Point.distance
Examples
========
>>> from sympy import Point, Segment
>>> p1, p2 = Point(0, 0), Point(4, 3)
>>> s1 = Segment(p1, p2)
>>> s1.length
5
>>> from sympy import Point3D, Segment3D
>>> p1, p2 = Point3D(0, 0, 0), Point3D(4, 3, 3)
>>> s1 = Segment3D(p1, p2)
>>> s1.length
sqrt(34)
"""
return Point.distance(self.p1, self.p2)
@property
def midpoint(self):
"""The midpoint of the line segment.
See Also
========
sympy.geometry.point.Point.midpoint
Examples
========
>>> from sympy import Point, Segment
>>> p1, p2 = Point(0, 0), Point(4, 3)
>>> s1 = Segment(p1, p2)
>>> s1.midpoint
Point2D(2, 3/2)
>>> from sympy import Point3D, Segment3D
>>> p1, p2 = Point3D(0, 0, 0), Point3D(4, 3, 3)
>>> s1 = Segment3D(p1, p2)
>>> s1.midpoint
Point3D(2, 3/2, 3/2)
"""
return Point.midpoint(self.p1, self.p2)
def perpendicular_bisector(self, p=None):
"""The perpendicular bisector of this segment.
If no point is specified or the point specified is not on the
bisector then the bisector is returned as a Line. Otherwise a
Segment is returned that joins the point specified and the
intersection of the bisector and the segment.
Parameters
==========
p : Point
Returns
=======
bisector : Line or Segment
See Also
========
LinearEntity.perpendicular_segment
Examples
========
>>> from sympy import Point, Segment
>>> p1, p2, p3 = Point(0, 0), Point(6, 6), Point(5, 1)
>>> s1 = Segment(p1, p2)
>>> s1.perpendicular_bisector()
Line2D(Point2D(3, 3), Point2D(-3, 9))
>>> s1.perpendicular_bisector(p3)
Segment2D(Point2D(5, 1), Point2D(3, 3))
"""
l = self.perpendicular_line(self.midpoint)
if p is not None:
p2 = Point(p, dim=self.ambient_dimension)
if p2 in l:
return Segment(p2, self.midpoint)
return l
def plot_interval(self, parameter='t'):
"""The plot interval for the default geometric plot of the Segment gives
values that will produce the full segment in a plot.
Parameters
==========
parameter : str, optional
Default value is 't'.
Returns
=======
plot_interval : list
[parameter, lower_bound, upper_bound]
Examples
========
>>> from sympy import Point, Segment
>>> p1, p2 = Point(0, 0), Point(5, 3)
>>> s1 = Segment(p1, p2)
>>> s1.plot_interval()
[t, 0, 1]
"""
t = _symbol(parameter, real=True)
return [t, 0, 1]
class LinearEntity2D(LinearEntity):
"""A base class for all linear entities (line, ray and segment)
in a 2-dimensional Euclidean space.
Attributes
==========
p1
p2
coefficients
slope
points
Notes
=====
This is an abstract class and is not meant to be instantiated.
See Also
========
sympy.geometry.entity.GeometryEntity
"""
@property
def bounds(self):
"""Return a tuple (xmin, ymin, xmax, ymax) representing the bounding
rectangle for the geometric figure.
"""
verts = self.points
xs = [p.x for p in verts]
ys = [p.y for p in verts]
return (min(xs), min(ys), max(xs), max(ys))
def perpendicular_line(self, p):
"""Create a new Line perpendicular to this linear entity which passes
through the point `p`.
Parameters
==========
p : Point
Returns
=======
line : Line
See Also
========
sympy.geometry.line.LinearEntity.is_perpendicular, perpendicular_segment
Examples
========
>>> from sympy import Point, Line
>>> p1, p2, p3 = Point(0, 0), Point(2, 3), Point(-2, 2)
>>> l1 = Line(p1, p2)
>>> l2 = l1.perpendicular_line(p3)
>>> p3 in l2
True
>>> l1.is_perpendicular(l2)
True
"""
p = Point(p, dim=self.ambient_dimension)
# any two lines in R^2 intersect, so blindly making
# a line through p in an orthogonal direction will work
return Line(p, p + self.direction.orthogonal_direction)
@property
def slope(self):
"""The slope of this linear entity, or infinity if vertical.
Returns
=======
slope : number or sympy expression
See Also
========
coefficients
Examples
========
>>> from sympy import Point, Line
>>> p1, p2 = Point(0, 0), Point(3, 5)
>>> l1 = Line(p1, p2)
>>> l1.slope
5/3
>>> p3 = Point(0, 4)
>>> l2 = Line(p1, p3)
>>> l2.slope
oo
"""
d1, d2 = (self.p1 - self.p2).args
if d1 == 0:
return S.Infinity
return simplify(d2/d1)
class Line2D(LinearEntity2D, Line):
"""An infinite line in space 2D.
A line is declared with two distinct points or a point and slope
as defined using keyword `slope`.
Parameters
==========
p1 : Point
pt : Point
slope : sympy expression
See Also
========
sympy.geometry.point.Point
Examples
========
>>> from sympy import Point
>>> from sympy.geometry import Line, Segment
>>> L = Line(Point(2,3), Point(3,5))
>>> L
Line2D(Point2D(2, 3), Point2D(3, 5))
>>> L.points
(Point2D(2, 3), Point2D(3, 5))
>>> L.equation()
-2*x + y + 1
>>> L.coefficients
(-2, 1, 1)
Instantiate with keyword ``slope``:
>>> Line(Point(0, 0), slope=0)
Line2D(Point2D(0, 0), Point2D(1, 0))
Instantiate with another linear object
>>> s = Segment((0, 0), (0, 1))
>>> Line(s).equation()
x
"""
def __new__(cls, p1, pt=None, slope=None, **kwargs):
if isinstance(p1, LinearEntity):
if pt is not None:
raise ValueError('When p1 is a LinearEntity, pt should be None')
p1, pt = Point._normalize_dimension(*p1.args, dim=2)
else:
p1 = Point(p1, dim=2)
if pt is not None and slope is None:
try:
p2 = Point(pt, dim=2)
except (NotImplementedError, TypeError, ValueError):
raise ValueError(filldedent('''
The 2nd argument was not a valid Point.
If it was a slope, enter it with keyword "slope".
'''))
elif slope is not None and pt is None:
slope = sympify(slope)
if slope.is_finite is False:
# when infinite slope, don't change x
dx = 0
dy = 1
else:
# go over 1 up slope
dx = 1
dy = slope
# XXX avoiding simplification by adding to coords directly
p2 = Point(p1.x + dx, p1.y + dy, evaluate=False)
else:
raise ValueError('A 2nd Point or keyword "slope" must be used.')
return LinearEntity2D.__new__(cls, p1, p2, **kwargs)
def _svg(self, scale_factor=1., fill_color="#66cc99"):
"""Returns SVG path element for the LinearEntity.
Parameters
==========
scale_factor : float
Multiplication factor for the SVG stroke-width. Default is 1.
fill_color : str, optional
Hex string for fill color. Default is "#66cc99".
"""
from sympy.core.evalf import N
verts = (N(self.p1), N(self.p2))
coords = ["{},{}".format(p.x, p.y) for p in verts]
path = "M {} L {}".format(coords[0], " L ".join(coords[1:]))
return (
'<path fill-rule="evenodd" fill="{2}" stroke="#555555" '
'stroke-width="{0}" opacity="0.6" d="{1}" '
'marker-start="url(#markerReverseArrow)" marker-end="url(#markerArrow)"/>'
).format(2.*scale_factor, path, fill_color)
@property
def coefficients(self):
"""The coefficients (`a`, `b`, `c`) for `ax + by + c = 0`.
See Also
========
sympy.geometry.line.Line2D.equation
Examples
========
>>> from sympy import Point, Line
>>> from sympy.abc import x, y
>>> p1, p2 = Point(0, 0), Point(5, 3)
>>> l = Line(p1, p2)
>>> l.coefficients
(-3, 5, 0)
>>> p3 = Point(x, y)
>>> l2 = Line(p1, p3)
>>> l2.coefficients
(-y, x, 0)
"""
p1, p2 = self.points
if p1.x == p2.x:
return (S.One, S.Zero, -p1.x)
elif p1.y == p2.y:
return (S.Zero, S.One, -p1.y)
return tuple([simplify(i) for i in
(self.p1.y - self.p2.y,
self.p2.x - self.p1.x,
self.p1.x*self.p2.y - self.p1.y*self.p2.x)])
def equation(self, x='x', y='y'):
"""The equation of the line: ax + by + c.
Parameters
==========
x : str, optional
The name to use for the x-axis, default value is 'x'.
y : str, optional
The name to use for the y-axis, default value is 'y'.
Returns
=======
equation : sympy expression
See Also
========
sympy.geometry.line.Line2D.coefficients
Examples
========
>>> from sympy import Point, Line
>>> p1, p2 = Point(1, 0), Point(5, 3)
>>> l1 = Line(p1, p2)
>>> l1.equation()
-3*x + 4*y + 3
"""
x = _symbol(x, real=True)
y = _symbol(y, real=True)
p1, p2 = self.points
if p1.x == p2.x:
return x - p1.x
elif p1.y == p2.y:
return y - p1.y
a, b, c = self.coefficients
return a*x + b*y + c
class Ray2D(LinearEntity2D, Ray):
"""
A Ray is a semi-line in the space with a source point and a direction.
Parameters
==========
p1 : Point
The source of the Ray
p2 : Point or radian value
This point determines the direction in which the Ray propagates.
If given as an angle it is interpreted in radians with the positive
direction being ccw.
Attributes
==========
source
xdirection
ydirection
See Also
========
sympy.geometry.point.Point, Line
Examples
========
>>> from sympy import Point, pi
>>> from sympy.geometry import Ray
>>> r = Ray(Point(2, 3), Point(3, 5))
>>> r
Ray2D(Point2D(2, 3), Point2D(3, 5))
>>> r.points
(Point2D(2, 3), Point2D(3, 5))
>>> r.source
Point2D(2, 3)
>>> r.xdirection
oo
>>> r.ydirection
oo
>>> r.slope
2
>>> Ray(Point(0, 0), angle=pi/4).slope
1
"""
def __new__(cls, p1, pt=None, angle=None, **kwargs):
p1 = Point(p1, dim=2)
if pt is not None and angle is None:
try:
p2 = Point(pt, dim=2)
except (NotImplementedError, TypeError, ValueError):
from sympy.utilities.misc import filldedent
raise ValueError(filldedent('''
The 2nd argument was not a valid Point; if
it was meant to be an angle it should be
given with keyword "angle".'''))
if p1 == p2:
raise ValueError('A Ray requires two distinct points.')
elif angle is not None and pt is None:
# we need to know if the angle is an odd multiple of pi/2
c = pi_coeff(sympify(angle))
p2 = None
if c is not None:
if c.is_Rational:
if c.q == 2:
if c.p == 1:
p2 = p1 + Point(0, 1)
elif c.p == 3:
p2 = p1 + Point(0, -1)
elif c.q == 1:
if c.p == 0:
p2 = p1 + Point(1, 0)
elif c.p == 1:
p2 = p1 + Point(-1, 0)
if p2 is None:
c *= S.Pi
else:
c = angle % (2*S.Pi)
if not p2:
m = 2*c/S.Pi
left = And(1 < m, m < 3) # is it in quadrant 2 or 3?
x = Piecewise((-1, left), (Piecewise((0, Eq(m % 1, 0)), (1, True)), True))
y = Piecewise((-tan(c), left), (Piecewise((1, Eq(m, 1)), (-1, Eq(m, 3)), (tan(c), True)), True))
p2 = p1 + Point(x, y)
else:
raise ValueError('A 2nd point or keyword "angle" must be used.')
return LinearEntity2D.__new__(cls, p1, p2, **kwargs)
@property
def xdirection(self):
"""The x direction of the ray.
Positive infinity if the ray points in the positive x direction,
negative infinity if the ray points in the negative x direction,
or 0 if the ray is vertical.
See Also
========
ydirection
Examples
========
>>> from sympy import Point, Ray
>>> p1, p2, p3 = Point(0, 0), Point(1, 1), Point(0, -1)
>>> r1, r2 = Ray(p1, p2), Ray(p1, p3)
>>> r1.xdirection
oo
>>> r2.xdirection
0
"""
if self.p1.x < self.p2.x:
return S.Infinity
elif self.p1.x == self.p2.x:
return S.Zero
else:
return S.NegativeInfinity
@property
def ydirection(self):
"""The y direction of the ray.
Positive infinity if the ray points in the positive y direction,
negative infinity if the ray points in the negative y direction,
or 0 if the ray is horizontal.
See Also
========
xdirection
Examples
========
>>> from sympy import Point, Ray
>>> p1, p2, p3 = Point(0, 0), Point(-1, -1), Point(-1, 0)
>>> r1, r2 = Ray(p1, p2), Ray(p1, p3)
>>> r1.ydirection
-oo
>>> r2.ydirection
0
"""
if self.p1.y < self.p2.y:
return S.Infinity
elif self.p1.y == self.p2.y:
return S.Zero
else:
return S.NegativeInfinity
def closing_angle(r1, r2):
"""Return the angle by which r2 must be rotated so it faces the same
direction as r1.
Parameters
==========
r1 : Ray2D
r2 : Ray2D
Returns
=======
angle : angle in radians (ccw angle is positive)
See Also
========
LinearEntity.angle_between
Examples
========
>>> from sympy import Ray, pi
>>> r1 = Ray((0, 0), (1, 0))
>>> r2 = r1.rotate(-pi/2)
>>> angle = r1.closing_angle(r2); angle
pi/2
>>> r2.rotate(angle).direction.unit == r1.direction.unit
True
>>> r2.closing_angle(r1)
-pi/2
"""
if not all(isinstance(r, Ray2D) for r in (r1, r2)):
# although the direction property is defined for
# all linear entities, only the Ray is truly a
# directed object
raise TypeError('Both arguments must be Ray2D objects.')
a1 = atan2(*list(reversed(r1.direction.args)))
a2 = atan2(*list(reversed(r2.direction.args)))
if a1*a2 < 0:
a1 = 2*S.Pi + a1 if a1 < 0 else a1
a2 = 2*S.Pi + a2 if a2 < 0 else a2
return a1 - a2
class Segment2D(LinearEntity2D, Segment):
"""A line segment in 2D space.
Parameters
==========
p1 : Point
p2 : Point
Attributes
==========
length : number or sympy expression
midpoint : Point
See Also
========
sympy.geometry.point.Point, Line
Examples
========
>>> from sympy import Point
>>> from sympy.geometry import Segment
>>> Segment((1, 0), (1, 1)) # tuples are interpreted as pts
Segment2D(Point2D(1, 0), Point2D(1, 1))
>>> s = Segment(Point(4, 3), Point(1, 1)); s
Segment2D(Point2D(4, 3), Point2D(1, 1))
>>> s.points
(Point2D(4, 3), Point2D(1, 1))
>>> s.slope
2/3
>>> s.length
sqrt(13)
>>> s.midpoint
Point2D(5/2, 2)
"""
def __new__(cls, p1, p2, **kwargs):
p1 = Point(p1, dim=2)
p2 = Point(p2, dim=2)
if p1 == p2:
return p1
return LinearEntity2D.__new__(cls, p1, p2, **kwargs)
def _svg(self, scale_factor=1., fill_color="#66cc99"):
"""Returns SVG path element for the LinearEntity.
Parameters
==========
scale_factor : float
Multiplication factor for the SVG stroke-width. Default is 1.
fill_color : str, optional
Hex string for fill color. Default is "#66cc99".
"""
from sympy.core.evalf import N
verts = (N(self.p1), N(self.p2))
coords = ["{},{}".format(p.x, p.y) for p in verts]
path = "M {} L {}".format(coords[0], " L ".join(coords[1:]))
return (
'<path fill-rule="evenodd" fill="{2}" stroke="#555555" '
'stroke-width="{0}" opacity="0.6" d="{1}" />'
).format(2.*scale_factor, path, fill_color)
class LinearEntity3D(LinearEntity):
"""An base class for all linear entities (line, ray and segment)
in a 3-dimensional Euclidean space.
Attributes
==========
p1
p2
direction_ratio
direction_cosine
points
Notes
=====
This is a base class and is not meant to be instantiated.
"""
def __new__(cls, p1, p2, **kwargs):
p1 = Point3D(p1, dim=3)
p2 = Point3D(p2, dim=3)
if p1 == p2:
# if it makes sense to return a Point, handle in subclass
raise ValueError(
"%s.__new__ requires two unique Points." % cls.__name__)
return GeometryEntity.__new__(cls, p1, p2, **kwargs)
ambient_dimension = 3
@property
def direction_ratio(self):
"""The direction ratio of a given line in 3D.
See Also
========
sympy.geometry.line.Line3D.equation
Examples
========
>>> from sympy import Point3D, Line3D
>>> p1, p2 = Point3D(0, 0, 0), Point3D(5, 3, 1)
>>> l = Line3D(p1, p2)
>>> l.direction_ratio
[5, 3, 1]
"""
p1, p2 = self.points
return p1.direction_ratio(p2)
@property
def direction_cosine(self):
"""The normalized direction ratio of a given line in 3D.
See Also
========
sympy.geometry.line.Line3D.equation
Examples
========
>>> from sympy import Point3D, Line3D
>>> p1, p2 = Point3D(0, 0, 0), Point3D(5, 3, 1)
>>> l = Line3D(p1, p2)
>>> l.direction_cosine
[sqrt(35)/7, 3*sqrt(35)/35, sqrt(35)/35]
>>> sum(i**2 for i in _)
1
"""
p1, p2 = self.points
return p1.direction_cosine(p2)
class Line3D(LinearEntity3D, Line):
"""An infinite 3D line in space.
A line is declared with two distinct points or a point and direction_ratio
as defined using keyword `direction_ratio`.
Parameters
==========
p1 : Point3D
pt : Point3D
direction_ratio : list
See Also
========
sympy.geometry.point.Point3D
sympy.geometry.line.Line
sympy.geometry.line.Line2D
Examples
========
>>> from sympy import Point3D
>>> from sympy.geometry import Line3D
>>> L = Line3D(Point3D(2, 3, 4), Point3D(3, 5, 1))
>>> L
Line3D(Point3D(2, 3, 4), Point3D(3, 5, 1))
>>> L.points
(Point3D(2, 3, 4), Point3D(3, 5, 1))
"""
def __new__(cls, p1, pt=None, direction_ratio=[], **kwargs):
if isinstance(p1, LinearEntity3D):
if pt is not None:
raise ValueError('if p1 is a LinearEntity, pt must be None.')
p1, pt = p1.args
else:
p1 = Point(p1, dim=3)
if pt is not None and len(direction_ratio) == 0:
pt = Point(pt, dim=3)
elif len(direction_ratio) == 3 and pt is None:
pt = Point3D(p1.x + direction_ratio[0], p1.y + direction_ratio[1],
p1.z + direction_ratio[2])
else:
raise ValueError('A 2nd Point or keyword "direction_ratio" must '
'be used.')
return LinearEntity3D.__new__(cls, p1, pt, **kwargs)
def equation(self, x='x', y='y', z='z', k=None):
"""Return the equations that define the line in 3D.
Parameters
==========
x : str, optional
The name to use for the x-axis, default value is 'x'.
y : str, optional
The name to use for the y-axis, default value is 'y'.
z : str, optional
The name to use for the z-axis, default value is 'z'.
Returns
=======
equation : Tuple of simultaneous equations
Examples
========
>>> from sympy import Point3D, Line3D, solve
>>> from sympy.abc import x, y, z
>>> p1, p2 = Point3D(1, 0, 0), Point3D(5, 3, 0)
>>> l1 = Line3D(p1, p2)
>>> eq = l1.equation(x, y, z); eq
(-3*x + 4*y + 3, z)
>>> solve(eq.subs(z, 0), (x, y, z))
{x: 4*y/3 + 1}
"""
if k is not None:
SymPyDeprecationWarning(
feature="equation() no longer needs 'k'",
issue=13742,
deprecated_since_version="1.2").warn()
from sympy import solve
x, y, z, k = [_symbol(i, real=True) for i in (x, y, z, 'k')]
p1, p2 = self.points
d1, d2, d3 = p1.direction_ratio(p2)
x1, y1, z1 = p1
eqs = [-d1*k + x - x1, -d2*k + y - y1, -d3*k + z - z1]
# eliminate k from equations by solving first eq with k for k
for i, e in enumerate(eqs):
if e.has(k):
kk = solve(eqs[i], k)[0]
eqs.pop(i)
break
return Tuple(*[i.subs(k, kk).as_numer_denom()[0] for i in eqs])
class Ray3D(LinearEntity3D, Ray):
"""
A Ray is a semi-line in the space with a source point and a direction.
Parameters
==========
p1 : Point3D
The source of the Ray
p2 : Point or a direction vector
direction_ratio: Determines the direction in which the Ray propagates.
Attributes
==========
source
xdirection
ydirection
zdirection
See Also
========
sympy.geometry.point.Point3D, Line3D
Examples
========
>>> from sympy import Point3D
>>> from sympy.geometry import Ray3D
>>> r = Ray3D(Point3D(2, 3, 4), Point3D(3, 5, 0))
>>> r
Ray3D(Point3D(2, 3, 4), Point3D(3, 5, 0))
>>> r.points
(Point3D(2, 3, 4), Point3D(3, 5, 0))
>>> r.source
Point3D(2, 3, 4)
>>> r.xdirection
oo
>>> r.ydirection
oo
>>> r.direction_ratio
[1, 2, -4]
"""
def __new__(cls, p1, pt=None, direction_ratio=[], **kwargs):
from sympy.utilities.misc import filldedent
if isinstance(p1, LinearEntity3D):
if pt is not None:
raise ValueError('If p1 is a LinearEntity, pt must be None')
p1, pt = p1.args
else:
p1 = Point(p1, dim=3)
if pt is not None and len(direction_ratio) == 0:
pt = Point(pt, dim=3)
elif len(direction_ratio) == 3 and pt is None:
pt = Point3D(p1.x + direction_ratio[0], p1.y + direction_ratio[1],
p1.z + direction_ratio[2])
else:
raise ValueError(filldedent('''
A 2nd Point or keyword "direction_ratio" must be used.
'''))
return LinearEntity3D.__new__(cls, p1, pt, **kwargs)
@property
def xdirection(self):
"""The x direction of the ray.
Positive infinity if the ray points in the positive x direction,
negative infinity if the ray points in the negative x direction,
or 0 if the ray is vertical.
See Also
========
ydirection
Examples
========
>>> from sympy import Point3D, Ray3D
>>> p1, p2, p3 = Point3D(0, 0, 0), Point3D(1, 1, 1), Point3D(0, -1, 0)
>>> r1, r2 = Ray3D(p1, p2), Ray3D(p1, p3)
>>> r1.xdirection
oo
>>> r2.xdirection
0
"""
if self.p1.x < self.p2.x:
return S.Infinity
elif self.p1.x == self.p2.x:
return S.Zero
else:
return S.NegativeInfinity
@property
def ydirection(self):
"""The y direction of the ray.
Positive infinity if the ray points in the positive y direction,
negative infinity if the ray points in the negative y direction,
or 0 if the ray is horizontal.
See Also
========
xdirection
Examples
========
>>> from sympy import Point3D, Ray3D
>>> p1, p2, p3 = Point3D(0, 0, 0), Point3D(-1, -1, -1), Point3D(-1, 0, 0)
>>> r1, r2 = Ray3D(p1, p2), Ray3D(p1, p3)
>>> r1.ydirection
-oo
>>> r2.ydirection
0
"""
if self.p1.y < self.p2.y:
return S.Infinity
elif self.p1.y == self.p2.y:
return S.Zero
else:
return S.NegativeInfinity
@property
def zdirection(self):
"""The z direction of the ray.
Positive infinity if the ray points in the positive z direction,
negative infinity if the ray points in the negative z direction,
or 0 if the ray is horizontal.
See Also
========
xdirection
Examples
========
>>> from sympy import Point3D, Ray3D
>>> p1, p2, p3 = Point3D(0, 0, 0), Point3D(-1, -1, -1), Point3D(-1, 0, 0)
>>> r1, r2 = Ray3D(p1, p2), Ray3D(p1, p3)
>>> r1.ydirection
-oo
>>> r2.ydirection
0
>>> r2.zdirection
0
"""
if self.p1.z < self.p2.z:
return S.Infinity
elif self.p1.z == self.p2.z:
return S.Zero
else:
return S.NegativeInfinity
class Segment3D(LinearEntity3D, Segment):
"""A line segment in a 3D space.
Parameters
==========
p1 : Point3D
p2 : Point3D
Attributes
==========
length : number or sympy expression
midpoint : Point3D
See Also
========
sympy.geometry.point.Point3D, Line3D
Examples
========
>>> from sympy import Point3D
>>> from sympy.geometry import Segment3D
>>> Segment3D((1, 0, 0), (1, 1, 1)) # tuples are interpreted as pts
Segment3D(Point3D(1, 0, 0), Point3D(1, 1, 1))
>>> s = Segment3D(Point3D(4, 3, 9), Point3D(1, 1, 7)); s
Segment3D(Point3D(4, 3, 9), Point3D(1, 1, 7))
>>> s.points
(Point3D(4, 3, 9), Point3D(1, 1, 7))
>>> s.length
sqrt(17)
>>> s.midpoint
Point3D(5/2, 2, 8)
"""
def __new__(cls, p1, p2, **kwargs):
p1 = Point(p1, dim=3)
p2 = Point(p2, dim=3)
if p1 == p2:
return p1
return LinearEntity3D.__new__(cls, p1, p2, **kwargs)
|
21942f66403d84e7304f9c18fe8fe80bfbcb3e1b76b6a6ac3be28c4bc91c8100 | from sympy.core import Expr, S, Symbol, oo, pi, sympify
from sympy.core.compatibility import as_int, ordered
from sympy.core.symbol import _symbol, Dummy, symbols
from sympy.functions.elementary.complexes import sign
from sympy.functions.elementary.piecewise import Piecewise
from sympy.functions.elementary.trigonometric import cos, sin, tan
from sympy.geometry.exceptions import GeometryError
from sympy.logic import And
from sympy.matrices import Matrix
from sympy.simplify import simplify
from sympy.utilities import default_sort_key
from sympy.utilities.iterables import has_dups, has_variety, uniq, rotate_left, least_rotation
from sympy.utilities.misc import func_name
from .entity import GeometryEntity, GeometrySet
from .point import Point
from .ellipse import Circle
from .line import Line, Segment, Ray
import warnings
class Polygon(GeometrySet):
"""A two-dimensional polygon.
A simple polygon in space. Can be constructed from a sequence of points
or from a center, radius, number of sides and rotation angle.
Parameters
==========
vertices : sequence of Points
Optional parameters
==========
n : If > 0, an n-sided RegularPolygon is created. See below.
Default value is 0.
Attributes
==========
area
angles
perimeter
vertices
centroid
sides
Raises
======
GeometryError
If all parameters are not Points.
See Also
========
sympy.geometry.point.Point, sympy.geometry.line.Segment, Triangle
Notes
=====
Polygons are treated as closed paths rather than 2D areas so
some calculations can be be negative or positive (e.g., area)
based on the orientation of the points.
Any consecutive identical points are reduced to a single point
and any points collinear and between two points will be removed
unless they are needed to define an explicit intersection (see examples).
A Triangle, Segment or Point will be returned when there are 3 or
fewer points provided.
Examples
========
>>> from sympy import Polygon, pi
>>> p1, p2, p3, p4, p5 = [(0, 0), (1, 0), (5, 1), (0, 1), (3, 0)]
>>> Polygon(p1, p2, p3, p4)
Polygon(Point2D(0, 0), Point2D(1, 0), Point2D(5, 1), Point2D(0, 1))
>>> Polygon(p1, p2)
Segment2D(Point2D(0, 0), Point2D(1, 0))
>>> Polygon(p1, p2, p5)
Segment2D(Point2D(0, 0), Point2D(3, 0))
The area of a polygon is calculated as positive when vertices are
traversed in a ccw direction. When the sides of a polygon cross the
area will have positive and negative contributions. The following
defines a Z shape where the bottom right connects back to the top
left.
>>> Polygon((0, 2), (2, 2), (0, 0), (2, 0)).area
0
When the the keyword `n` is used to define the number of sides of the
Polygon then a RegularPolygon is created and the other arguments are
interpreted as center, radius and rotation. The unrotated RegularPolygon
will always have a vertex at Point(r, 0) where `r` is the radius of the
circle that circumscribes the RegularPolygon. Its method `spin` can be
used to increment that angle.
>>> p = Polygon((0,0), 1, n=3)
>>> p
RegularPolygon(Point2D(0, 0), 1, 3, 0)
>>> p.vertices[0]
Point2D(1, 0)
>>> p.args[0]
Point2D(0, 0)
>>> p.spin(pi/2)
>>> p.vertices[0]
Point2D(0, 1)
"""
def __new__(cls, *args, n = 0, **kwargs):
if n:
args = list(args)
# return a virtual polygon with n sides
if len(args) == 2: # center, radius
args.append(n)
elif len(args) == 3: # center, radius, rotation
args.insert(2, n)
return RegularPolygon(*args, **kwargs)
vertices = [Point(a, dim=2, **kwargs) for a in args]
# remove consecutive duplicates
nodup = []
for p in vertices:
if nodup and p == nodup[-1]:
continue
nodup.append(p)
if len(nodup) > 1 and nodup[-1] == nodup[0]:
nodup.pop() # last point was same as first
# remove collinear points
i = -3
while i < len(nodup) - 3 and len(nodup) > 2:
a, b, c = nodup[i], nodup[i + 1], nodup[i + 2]
if Point.is_collinear(a, b, c):
nodup.pop(i + 1)
if a == c:
nodup.pop(i)
else:
i += 1
vertices = list(nodup)
if len(vertices) > 3:
return GeometryEntity.__new__(cls, *vertices, **kwargs)
elif len(vertices) == 3:
return Triangle(*vertices, **kwargs)
elif len(vertices) == 2:
return Segment(*vertices, **kwargs)
else:
return Point(*vertices, **kwargs)
@property
def area(self):
"""
The area of the polygon.
Notes
=====
The area calculation can be positive or negative based on the
orientation of the points. If any side of the polygon crosses
any other side, there will be areas having opposite signs.
See Also
========
sympy.geometry.ellipse.Ellipse.area
Examples
========
>>> from sympy import Point, Polygon
>>> p1, p2, p3, p4 = map(Point, [(0, 0), (1, 0), (5, 1), (0, 1)])
>>> poly = Polygon(p1, p2, p3, p4)
>>> poly.area
3
In the Z shaped polygon (with the lower right connecting back
to the upper left) the areas cancel out:
>>> Z = Polygon((0, 1), (1, 1), (0, 0), (1, 0))
>>> Z.area
0
In the M shaped polygon, areas do not cancel because no side
crosses any other (though there is a point of contact).
>>> M = Polygon((0, 0), (0, 1), (2, 0), (3, 1), (3, 0))
>>> M.area
-3/2
"""
area = 0
args = self.args
for i in range(len(args)):
x1, y1 = args[i - 1].args
x2, y2 = args[i].args
area += x1*y2 - x2*y1
return simplify(area) / 2
@staticmethod
def _isright(a, b, c):
"""Return True/False for cw/ccw orientation.
Examples
========
>>> from sympy import Point, Polygon
>>> a, b, c = [Point(i) for i in [(0, 0), (1, 1), (1, 0)]]
>>> Polygon._isright(a, b, c)
True
>>> Polygon._isright(a, c, b)
False
"""
ba = b - a
ca = c - a
t_area = simplify(ba.x*ca.y - ca.x*ba.y)
res = t_area.is_nonpositive
if res is None:
raise ValueError("Can't determine orientation")
return res
@property
def angles(self):
"""The internal angle at each vertex.
Returns
=======
angles : dict
A dictionary where each key is a vertex and each value is the
internal angle at that vertex. The vertices are represented as
Points.
See Also
========
sympy.geometry.point.Point, sympy.geometry.line.LinearEntity.angle_between
Examples
========
>>> from sympy import Point, Polygon
>>> p1, p2, p3, p4 = map(Point, [(0, 0), (1, 0), (5, 1), (0, 1)])
>>> poly = Polygon(p1, p2, p3, p4)
>>> poly.angles[p1]
pi/2
>>> poly.angles[p2]
acos(-4*sqrt(17)/17)
"""
# Determine orientation of points
args = self.vertices
cw = self._isright(args[-1], args[0], args[1])
ret = {}
for i in range(len(args)):
a, b, c = args[i - 2], args[i - 1], args[i]
ang = Ray(b, a).angle_between(Ray(b, c))
if cw ^ self._isright(a, b, c):
ret[b] = 2*S.Pi - ang
else:
ret[b] = ang
return ret
@property
def ambient_dimension(self):
return self.vertices[0].ambient_dimension
@property
def perimeter(self):
"""The perimeter of the polygon.
Returns
=======
perimeter : number or Basic instance
See Also
========
sympy.geometry.line.Segment.length
Examples
========
>>> from sympy import Point, Polygon
>>> p1, p2, p3, p4 = map(Point, [(0, 0), (1, 0), (5, 1), (0, 1)])
>>> poly = Polygon(p1, p2, p3, p4)
>>> poly.perimeter
sqrt(17) + 7
"""
p = 0
args = self.vertices
for i in range(len(args)):
p += args[i - 1].distance(args[i])
return simplify(p)
@property
def vertices(self):
"""The vertices of the polygon.
Returns
=======
vertices : list of Points
Notes
=====
When iterating over the vertices, it is more efficient to index self
rather than to request the vertices and index them. Only use the
vertices when you want to process all of them at once. This is even
more important with RegularPolygons that calculate each vertex.
See Also
========
sympy.geometry.point.Point
Examples
========
>>> from sympy import Point, Polygon
>>> p1, p2, p3, p4 = map(Point, [(0, 0), (1, 0), (5, 1), (0, 1)])
>>> poly = Polygon(p1, p2, p3, p4)
>>> poly.vertices
[Point2D(0, 0), Point2D(1, 0), Point2D(5, 1), Point2D(0, 1)]
>>> poly.vertices[0]
Point2D(0, 0)
"""
return list(self.args)
@property
def centroid(self):
"""The centroid of the polygon.
Returns
=======
centroid : Point
See Also
========
sympy.geometry.point.Point, sympy.geometry.util.centroid
Examples
========
>>> from sympy import Point, Polygon
>>> p1, p2, p3, p4 = map(Point, [(0, 0), (1, 0), (5, 1), (0, 1)])
>>> poly = Polygon(p1, p2, p3, p4)
>>> poly.centroid
Point2D(31/18, 11/18)
"""
A = 1/(6*self.area)
cx, cy = 0, 0
args = self.args
for i in range(len(args)):
x1, y1 = args[i - 1].args
x2, y2 = args[i].args
v = x1*y2 - x2*y1
cx += v*(x1 + x2)
cy += v*(y1 + y2)
return Point(simplify(A*cx), simplify(A*cy))
def second_moment_of_area(self, point=None):
"""Returns the second moment and product moment of area of a two dimensional polygon.
Parameters
==========
point : Point, two-tuple of sympifyable objects, or None(default=None)
point is the point about which second moment of area is to be found.
If "point=None" it will be calculated about the axis passing through the
centroid of the polygon.
Returns
=======
I_xx, I_yy, I_xy : number or sympy expression
I_xx, I_yy are second moment of area of a two dimensional polygon.
I_xy is product moment of area of a two dimensional polygon.
Examples
========
>>> from sympy import Polygon, symbols
>>> a, b = symbols('a, b')
>>> p1, p2, p3, p4, p5 = [(0, 0), (a, 0), (a, b), (0, b), (a/3, b/3)]
>>> rectangle = Polygon(p1, p2, p3, p4)
>>> rectangle.second_moment_of_area()
(a*b**3/12, a**3*b/12, 0)
>>> rectangle.second_moment_of_area(p5)
(a*b**3/9, a**3*b/9, a**2*b**2/36)
References
==========
https://en.wikipedia.org/wiki/Second_moment_of_area
"""
I_xx, I_yy, I_xy = 0, 0, 0
args = self.vertices
for i in range(len(args)):
x1, y1 = args[i-1].args
x2, y2 = args[i].args
v = x1*y2 - x2*y1
I_xx += (y1**2 + y1*y2 + y2**2)*v
I_yy += (x1**2 + x1*x2 + x2**2)*v
I_xy += (x1*y2 + 2*x1*y1 + 2*x2*y2 + x2*y1)*v
A = self.area
c_x = self.centroid[0]
c_y = self.centroid[1]
# parallel axis theorem
I_xx_c = (I_xx/12) - (A*(c_y**2))
I_yy_c = (I_yy/12) - (A*(c_x**2))
I_xy_c = (I_xy/24) - (A*(c_x*c_y))
if point is None:
return I_xx_c, I_yy_c, I_xy_c
I_xx = (I_xx_c + A*((point[1]-c_y)**2))
I_yy = (I_yy_c + A*((point[0]-c_x)**2))
I_xy = (I_xy_c + A*((point[0]-c_x)*(point[1]-c_y)))
return I_xx, I_yy, I_xy
def first_moment_of_area(self, point=None):
"""
Returns the first moment of area of a two-dimensional polygon with
respect to a certain point of interest.
First moment of area is a measure of the distribution of the area
of a polygon in relation to an axis. The first moment of area of
the entire polygon about its own centroid is always zero. Therefore,
here it is calculated for an area, above or below a certain point
of interest, that makes up a smaller portion of the polygon. This
area is bounded by the point of interest and the extreme end
(top or bottom) of the polygon. The first moment for this area is
is then determined about the centroidal axis of the initial polygon.
References
==========
https://skyciv.com/docs/tutorials/section-tutorials/calculating-the-statical-or-first-moment-of-area-of-beam-sections/?cc=BMD
https://mechanicalc.com/reference/cross-sections
Parameters
==========
point: Point, two-tuple of sympifyable objects, or None (default=None)
point is the point above or below which the area of interest lies
If ``point=None`` then the centroid acts as the point of interest.
Returns
=======
Q_x, Q_y: number or sympy expressions
Q_x is the first moment of area about the x-axis
Q_y is the first moment of area about the y-axis
A negative sign indicates that the section modulus is
determined for a section below (or left of) the centroidal axis
Examples
========
>>> from sympy import Point, Polygon
>>> a, b = 50, 10
>>> p1, p2, p3, p4 = [(0, b), (0, 0), (a, 0), (a, b)]
>>> p = Polygon(p1, p2, p3, p4)
>>> p.first_moment_of_area()
(625, 3125)
>>> p.first_moment_of_area(point=Point(30, 7))
(525, 3000)
"""
if point:
xc, yc = self.centroid
else:
point = self.centroid
xc, yc = point
h_line = Line(point, slope=0)
v_line = Line(point, slope=S.Infinity)
h_poly = self.cut_section(h_line)
v_poly = self.cut_section(v_line)
poly_1 = h_poly[0] if h_poly[0].area <= h_poly[1].area else h_poly[1]
poly_2 = v_poly[0] if v_poly[0].area <= v_poly[1].area else v_poly[1]
Q_x = (poly_1.centroid.y - yc)*poly_1.area
Q_y = (poly_2.centroid.x - xc)*poly_2.area
return Q_x, Q_y
def polar_second_moment_of_area(self):
"""Returns the polar modulus of a two-dimensional polygon
It is a constituent of the second moment of area, linked through
the perpendicular axis theorem. While the planar second moment of
area describes an object's resistance to deflection (bending) when
subjected to a force applied to a plane parallel to the central
axis, the polar second moment of area describes an object's
resistance to deflection when subjected to a moment applied in a
plane perpendicular to the object's central axis (i.e. parallel to
the cross-section)
References
==========
https://en.wikipedia.org/wiki/Polar_moment_of_inertia
Examples
========
>>> from sympy import Polygon, symbols
>>> a, b = symbols('a, b')
>>> rectangle = Polygon((0, 0), (a, 0), (a, b), (0, b))
>>> rectangle.polar_second_moment_of_area()
a**3*b/12 + a*b**3/12
"""
second_moment = self.second_moment_of_area()
return second_moment[0] + second_moment[1]
def section_modulus(self, point=None):
"""Returns a tuple with the section modulus of a two-dimensional
polygon.
Section modulus is a geometric property of a polygon defined as the
ratio of second moment of area to the distance of the extreme end of
the polygon from the centroidal axis.
References
==========
https://en.wikipedia.org/wiki/Section_modulus
Parameters
==========
point : Point, two-tuple of sympifyable objects, or None(default=None)
point is the point at which section modulus is to be found.
If "point=None" it will be calculated for the point farthest from the
centroidal axis of the polygon.
Returns
=======
S_x, S_y: numbers or SymPy expressions
S_x is the section modulus with respect to the x-axis
S_y is the section modulus with respect to the y-axis
A negative sign indicates that the section modulus is
determined for a point below the centroidal axis
Examples
========
>>> from sympy import symbols, Polygon, Point
>>> a, b = symbols('a, b', positive=True)
>>> rectangle = Polygon((0, 0), (a, 0), (a, b), (0, b))
>>> rectangle.section_modulus()
(a*b**2/6, a**2*b/6)
>>> rectangle.section_modulus(Point(a/4, b/4))
(-a*b**2/3, -a**2*b/3)
"""
x_c, y_c = self.centroid
if point is None:
# taking x and y as maximum distances from centroid
x_min, y_min, x_max, y_max = self.bounds
y = max(y_c - y_min, y_max - y_c)
x = max(x_c - x_min, x_max - x_c)
else:
# taking x and y as distances of the given point from the centroid
y = point.y - y_c
x = point.x - x_c
second_moment= self.second_moment_of_area()
S_x = second_moment[0]/y
S_y = second_moment[1]/x
return S_x, S_y
@property
def sides(self):
"""The directed line segments that form the sides of the polygon.
Returns
=======
sides : list of sides
Each side is a directed Segment.
See Also
========
sympy.geometry.point.Point, sympy.geometry.line.Segment
Examples
========
>>> from sympy import Point, Polygon
>>> p1, p2, p3, p4 = map(Point, [(0, 0), (1, 0), (5, 1), (0, 1)])
>>> poly = Polygon(p1, p2, p3, p4)
>>> poly.sides
[Segment2D(Point2D(0, 0), Point2D(1, 0)),
Segment2D(Point2D(1, 0), Point2D(5, 1)),
Segment2D(Point2D(5, 1), Point2D(0, 1)), Segment2D(Point2D(0, 1), Point2D(0, 0))]
"""
res = []
args = self.vertices
for i in range(-len(args), 0):
res.append(Segment(args[i], args[i + 1]))
return res
@property
def bounds(self):
"""Return a tuple (xmin, ymin, xmax, ymax) representing the bounding
rectangle for the geometric figure.
"""
verts = self.vertices
xs = [p.x for p in verts]
ys = [p.y for p in verts]
return (min(xs), min(ys), max(xs), max(ys))
def is_convex(self):
"""Is the polygon convex?
A polygon is convex if all its interior angles are less than 180
degrees and there are no intersections between sides.
Returns
=======
is_convex : boolean
True if this polygon is convex, False otherwise.
See Also
========
sympy.geometry.util.convex_hull
Examples
========
>>> from sympy import Point, Polygon
>>> p1, p2, p3, p4 = map(Point, [(0, 0), (1, 0), (5, 1), (0, 1)])
>>> poly = Polygon(p1, p2, p3, p4)
>>> poly.is_convex()
True
"""
# Determine orientation of points
args = self.vertices
cw = self._isright(args[-2], args[-1], args[0])
for i in range(1, len(args)):
if cw ^ self._isright(args[i - 2], args[i - 1], args[i]):
return False
# check for intersecting sides
sides = self.sides
for i, si in enumerate(sides):
pts = si.args
# exclude the sides connected to si
for j in range(1 if i == len(sides) - 1 else 0, i - 1):
sj = sides[j]
if sj.p1 not in pts and sj.p2 not in pts:
hit = si.intersection(sj)
if hit:
return False
return True
def encloses_point(self, p):
"""
Return True if p is enclosed by (is inside of) self.
Notes
=====
Being on the border of self is considered False.
Parameters
==========
p : Point
Returns
=======
encloses_point : True, False or None
See Also
========
sympy.geometry.point.Point, sympy.geometry.ellipse.Ellipse.encloses_point
Examples
========
>>> from sympy import Polygon, Point
>>> p = Polygon((0, 0), (4, 0), (4, 4))
>>> p.encloses_point(Point(2, 1))
True
>>> p.encloses_point(Point(2, 2))
False
>>> p.encloses_point(Point(5, 5))
False
References
==========
[1] http://paulbourke.net/geometry/polygonmesh/#insidepoly
"""
p = Point(p, dim=2)
if p in self.vertices or any(p in s for s in self.sides):
return False
# move to p, checking that the result is numeric
lit = []
for v in self.vertices:
lit.append(v - p) # the difference is simplified
if lit[-1].free_symbols:
return None
poly = Polygon(*lit)
# polygon closure is assumed in the following test but Polygon removes duplicate pts so
# the last point has to be added so all sides are computed. Using Polygon.sides is
# not good since Segments are unordered.
args = poly.args
indices = list(range(-len(args), 1))
if poly.is_convex():
orientation = None
for i in indices:
a = args[i]
b = args[i + 1]
test = ((-a.y)*(b.x - a.x) - (-a.x)*(b.y - a.y)).is_negative
if orientation is None:
orientation = test
elif test is not orientation:
return False
return True
hit_odd = False
p1x, p1y = args[0].args
for i in indices[1:]:
p2x, p2y = args[i].args
if 0 > min(p1y, p2y):
if 0 <= max(p1y, p2y):
if 0 <= max(p1x, p2x):
if p1y != p2y:
xinters = (-p1y)*(p2x - p1x)/(p2y - p1y) + p1x
if p1x == p2x or 0 <= xinters:
hit_odd = not hit_odd
p1x, p1y = p2x, p2y
return hit_odd
def arbitrary_point(self, parameter='t'):
"""A parameterized point on the polygon.
The parameter, varying from 0 to 1, assigns points to the position on
the perimeter that is that fraction of the total perimeter. So the
point evaluated at t=1/2 would return the point from the first vertex
that is 1/2 way around the polygon.
Parameters
==========
parameter : str, optional
Default value is 't'.
Returns
=======
arbitrary_point : Point
Raises
======
ValueError
When `parameter` already appears in the Polygon's definition.
See Also
========
sympy.geometry.point.Point
Examples
========
>>> from sympy import Polygon, Symbol
>>> t = Symbol('t', real=True)
>>> tri = Polygon((0, 0), (1, 0), (1, 1))
>>> p = tri.arbitrary_point('t')
>>> perimeter = tri.perimeter
>>> s1, s2 = [s.length for s in tri.sides[:2]]
>>> p.subs(t, (s1 + s2/2)/perimeter)
Point2D(1, 1/2)
"""
t = _symbol(parameter, real=True)
if t.name in (f.name for f in self.free_symbols):
raise ValueError('Symbol %s already appears in object and cannot be used as a parameter.' % t.name)
sides = []
perimeter = self.perimeter
perim_fraction_start = 0
for s in self.sides:
side_perim_fraction = s.length/perimeter
perim_fraction_end = perim_fraction_start + side_perim_fraction
pt = s.arbitrary_point(parameter).subs(
t, (t - perim_fraction_start)/side_perim_fraction)
sides.append(
(pt, (And(perim_fraction_start <= t, t < perim_fraction_end))))
perim_fraction_start = perim_fraction_end
return Piecewise(*sides)
def parameter_value(self, other, t):
from sympy.solvers.solvers import solve
if not isinstance(other,GeometryEntity):
other = Point(other, dim=self.ambient_dimension)
if not isinstance(other,Point):
raise ValueError("other must be a point")
if other.free_symbols:
raise NotImplementedError('non-numeric coordinates')
unknown = False
T = Dummy('t', real=True)
p = self.arbitrary_point(T)
for pt, cond in p.args:
sol = solve(pt - other, T, dict=True)
if not sol:
continue
value = sol[0][T]
if simplify(cond.subs(T, value)) == True:
return {t: value}
unknown = True
if unknown:
raise ValueError("Given point may not be on %s" % func_name(self))
raise ValueError("Given point is not on %s" % func_name(self))
def plot_interval(self, parameter='t'):
"""The plot interval for the default geometric plot of the polygon.
Parameters
==========
parameter : str, optional
Default value is 't'.
Returns
=======
plot_interval : list (plot interval)
[parameter, lower_bound, upper_bound]
Examples
========
>>> from sympy import Polygon
>>> p = Polygon((0, 0), (1, 0), (1, 1))
>>> p.plot_interval()
[t, 0, 1]
"""
t = Symbol(parameter, real=True)
return [t, 0, 1]
def intersection(self, o):
"""The intersection of polygon and geometry entity.
The intersection may be empty and can contain individual Points and
complete Line Segments.
Parameters
==========
other: GeometryEntity
Returns
=======
intersection : list
The list of Segments and Points
See Also
========
sympy.geometry.point.Point, sympy.geometry.line.Segment
Examples
========
>>> from sympy import Point, Polygon, Line
>>> p1, p2, p3, p4 = map(Point, [(0, 0), (1, 0), (5, 1), (0, 1)])
>>> poly1 = Polygon(p1, p2, p3, p4)
>>> p5, p6, p7 = map(Point, [(3, 2), (1, -1), (0, 2)])
>>> poly2 = Polygon(p5, p6, p7)
>>> poly1.intersection(poly2)
[Point2D(1/3, 1), Point2D(2/3, 0), Point2D(9/5, 1/5), Point2D(7/3, 1)]
>>> poly1.intersection(Line(p1, p2))
[Segment2D(Point2D(0, 0), Point2D(1, 0))]
>>> poly1.intersection(p1)
[Point2D(0, 0)]
"""
intersection_result = []
k = o.sides if isinstance(o, Polygon) else [o]
for side in self.sides:
for side1 in k:
intersection_result.extend(side.intersection(side1))
intersection_result = list(uniq(intersection_result))
points = [entity for entity in intersection_result if isinstance(entity, Point)]
segments = [entity for entity in intersection_result if isinstance(entity, Segment)]
if points and segments:
points_in_segments = list(uniq([point for point in points for segment in segments if point in segment]))
if points_in_segments:
for i in points_in_segments:
points.remove(i)
return list(ordered(segments + points))
else:
return list(ordered(intersection_result))
def cut_section(self, line):
"""
Returns a tuple of two polygon segments that lie above and below
the intersecting line respectively.
Parameters
==========
line: Line object of geometry module
line which cuts the Polygon. The part of the Polygon that lies
above and below this line is returned.
Returns
=======
upper_polygon, lower_polygon: Polygon objects or None
upper_polygon is the polygon that lies above the given line.
lower_polygon is the polygon that lies below the given line.
upper_polygon and lower polygon are ``None`` when no polygon
exists above the line or below the line.
Raises
======
ValueError: When the line does not intersect the polygon
References
==========
https://github.com/sympy/sympy/wiki/A-method-to-return-a-cut-section-of-any-polygon-geometry
Examples
========
>>> from sympy import Polygon, Line
>>> a, b = 20, 10
>>> p1, p2, p3, p4 = [(0, b), (0, 0), (a, 0), (a, b)]
>>> rectangle = Polygon(p1, p2, p3, p4)
>>> t = rectangle.cut_section(Line((0, 5), slope=0))
>>> t
(Polygon(Point2D(0, 10), Point2D(0, 5), Point2D(20, 5), Point2D(20, 10)),
Polygon(Point2D(0, 5), Point2D(0, 0), Point2D(20, 0), Point2D(20, 5)))
>>> upper_segment, lower_segment = t
>>> upper_segment.area
100
>>> upper_segment.centroid
Point2D(10, 15/2)
>>> lower_segment.centroid
Point2D(10, 5/2)
"""
intersection_points = self.intersection(line)
if not intersection_points:
raise ValueError("This line does not intersect the polygon")
points = list(self.vertices)
points.append(points[0])
x, y = symbols('x, y', real=True, cls=Dummy)
eq = line.equation(x, y)
# considering equation of line to be `ax +by + c`
a = eq.coeff(x)
b = eq.coeff(y)
upper_vertices = []
lower_vertices = []
# prev is true when previous point is above the line
prev = True
prev_point = None
for point in points:
# when coefficient of y is 0, right side of the line is
# considered
compare = eq.subs({x: point.x, y: point.y})/b if b \
else eq.subs(x, point.x)/a
# if point lies above line
if compare > 0:
if not prev:
# if previous point lies below the line, the intersection
# point of the polygon egde and the line has to be included
edge = Line(point, prev_point)
new_point = edge.intersection(line)
upper_vertices.append(new_point[0])
lower_vertices.append(new_point[0])
upper_vertices.append(point)
prev = True
else:
if prev and prev_point:
edge = Line(point, prev_point)
new_point = edge.intersection(line)
upper_vertices.append(new_point[0])
lower_vertices.append(new_point[0])
lower_vertices.append(point)
prev = False
prev_point = point
upper_polygon, lower_polygon = None, None
if upper_vertices and isinstance(Polygon(*upper_vertices), Polygon):
upper_polygon = Polygon(*upper_vertices)
if lower_vertices and isinstance(Polygon(*lower_vertices), Polygon):
lower_polygon = Polygon(*lower_vertices)
return upper_polygon, lower_polygon
def distance(self, o):
"""
Returns the shortest distance between self and o.
If o is a point, then self does not need to be convex.
If o is another polygon self and o must be convex.
Examples
========
>>> from sympy import Point, Polygon, RegularPolygon
>>> p1, p2 = map(Point, [(0, 0), (7, 5)])
>>> poly = Polygon(*RegularPolygon(p1, 1, 3).vertices)
>>> poly.distance(p2)
sqrt(61)
"""
if isinstance(o, Point):
dist = oo
for side in self.sides:
current = side.distance(o)
if current == 0:
return S.Zero
elif current < dist:
dist = current
return dist
elif isinstance(o, Polygon) and self.is_convex() and o.is_convex():
return self._do_poly_distance(o)
raise NotImplementedError()
def _do_poly_distance(self, e2):
"""
Calculates the least distance between the exteriors of two
convex polygons e1 and e2. Does not check for the convexity
of the polygons as this is checked by Polygon.distance.
Notes
=====
- Prints a warning if the two polygons possibly intersect as the return
value will not be valid in such a case. For a more through test of
intersection use intersection().
See Also
========
sympy.geometry.point.Point.distance
Examples
========
>>> from sympy.geometry import Point, Polygon
>>> square = Polygon(Point(0, 0), Point(0, 1), Point(1, 1), Point(1, 0))
>>> triangle = Polygon(Point(1, 2), Point(2, 2), Point(2, 1))
>>> square._do_poly_distance(triangle)
sqrt(2)/2
Description of method used
==========================
Method:
[1] http://cgm.cs.mcgill.ca/~orm/mind2p.html
Uses rotating calipers:
[2] https://en.wikipedia.org/wiki/Rotating_calipers
and antipodal points:
[3] https://en.wikipedia.org/wiki/Antipodal_point
"""
e1 = self
'''Tests for a possible intersection between the polygons and outputs a warning'''
e1_center = e1.centroid
e2_center = e2.centroid
e1_max_radius = S.Zero
e2_max_radius = S.Zero
for vertex in e1.vertices:
r = Point.distance(e1_center, vertex)
if e1_max_radius < r:
e1_max_radius = r
for vertex in e2.vertices:
r = Point.distance(e2_center, vertex)
if e2_max_radius < r:
e2_max_radius = r
center_dist = Point.distance(e1_center, e2_center)
if center_dist <= e1_max_radius + e2_max_radius:
warnings.warn("Polygons may intersect producing erroneous output")
'''
Find the upper rightmost vertex of e1 and the lowest leftmost vertex of e2
'''
e1_ymax = Point(0, -oo)
e2_ymin = Point(0, oo)
for vertex in e1.vertices:
if vertex.y > e1_ymax.y or (vertex.y == e1_ymax.y and vertex.x > e1_ymax.x):
e1_ymax = vertex
for vertex in e2.vertices:
if vertex.y < e2_ymin.y or (vertex.y == e2_ymin.y and vertex.x < e2_ymin.x):
e2_ymin = vertex
min_dist = Point.distance(e1_ymax, e2_ymin)
'''
Produce a dictionary with vertices of e1 as the keys and, for each vertex, the points
to which the vertex is connected as its value. The same is then done for e2.
'''
e1_connections = {}
e2_connections = {}
for side in e1.sides:
if side.p1 in e1_connections:
e1_connections[side.p1].append(side.p2)
else:
e1_connections[side.p1] = [side.p2]
if side.p2 in e1_connections:
e1_connections[side.p2].append(side.p1)
else:
e1_connections[side.p2] = [side.p1]
for side in e2.sides:
if side.p1 in e2_connections:
e2_connections[side.p1].append(side.p2)
else:
e2_connections[side.p1] = [side.p2]
if side.p2 in e2_connections:
e2_connections[side.p2].append(side.p1)
else:
e2_connections[side.p2] = [side.p1]
e1_current = e1_ymax
e2_current = e2_ymin
support_line = Line(Point(S.Zero, S.Zero), Point(S.One, S.Zero))
'''
Determine which point in e1 and e2 will be selected after e2_ymin and e1_ymax,
this information combined with the above produced dictionaries determines the
path that will be taken around the polygons
'''
point1 = e1_connections[e1_ymax][0]
point2 = e1_connections[e1_ymax][1]
angle1 = support_line.angle_between(Line(e1_ymax, point1))
angle2 = support_line.angle_between(Line(e1_ymax, point2))
if angle1 < angle2:
e1_next = point1
elif angle2 < angle1:
e1_next = point2
elif Point.distance(e1_ymax, point1) > Point.distance(e1_ymax, point2):
e1_next = point2
else:
e1_next = point1
point1 = e2_connections[e2_ymin][0]
point2 = e2_connections[e2_ymin][1]
angle1 = support_line.angle_between(Line(e2_ymin, point1))
angle2 = support_line.angle_between(Line(e2_ymin, point2))
if angle1 > angle2:
e2_next = point1
elif angle2 > angle1:
e2_next = point2
elif Point.distance(e2_ymin, point1) > Point.distance(e2_ymin, point2):
e2_next = point2
else:
e2_next = point1
'''
Loop which determines the distance between anti-podal pairs and updates the
minimum distance accordingly. It repeats until it reaches the starting position.
'''
while True:
e1_angle = support_line.angle_between(Line(e1_current, e1_next))
e2_angle = pi - support_line.angle_between(Line(
e2_current, e2_next))
if (e1_angle < e2_angle) is True:
support_line = Line(e1_current, e1_next)
e1_segment = Segment(e1_current, e1_next)
min_dist_current = e1_segment.distance(e2_current)
if min_dist_current.evalf() < min_dist.evalf():
min_dist = min_dist_current
if e1_connections[e1_next][0] != e1_current:
e1_current = e1_next
e1_next = e1_connections[e1_next][0]
else:
e1_current = e1_next
e1_next = e1_connections[e1_next][1]
elif (e1_angle > e2_angle) is True:
support_line = Line(e2_next, e2_current)
e2_segment = Segment(e2_current, e2_next)
min_dist_current = e2_segment.distance(e1_current)
if min_dist_current.evalf() < min_dist.evalf():
min_dist = min_dist_current
if e2_connections[e2_next][0] != e2_current:
e2_current = e2_next
e2_next = e2_connections[e2_next][0]
else:
e2_current = e2_next
e2_next = e2_connections[e2_next][1]
else:
support_line = Line(e1_current, e1_next)
e1_segment = Segment(e1_current, e1_next)
e2_segment = Segment(e2_current, e2_next)
min1 = e1_segment.distance(e2_next)
min2 = e2_segment.distance(e1_next)
min_dist_current = min(min1, min2)
if min_dist_current.evalf() < min_dist.evalf():
min_dist = min_dist_current
if e1_connections[e1_next][0] != e1_current:
e1_current = e1_next
e1_next = e1_connections[e1_next][0]
else:
e1_current = e1_next
e1_next = e1_connections[e1_next][1]
if e2_connections[e2_next][0] != e2_current:
e2_current = e2_next
e2_next = e2_connections[e2_next][0]
else:
e2_current = e2_next
e2_next = e2_connections[e2_next][1]
if e1_current == e1_ymax and e2_current == e2_ymin:
break
return min_dist
def _svg(self, scale_factor=1., fill_color="#66cc99"):
"""Returns SVG path element for the Polygon.
Parameters
==========
scale_factor : float
Multiplication factor for the SVG stroke-width. Default is 1.
fill_color : str, optional
Hex string for fill color. Default is "#66cc99".
"""
from sympy.core.evalf import N
verts = map(N, self.vertices)
coords = ["{},{}".format(p.x, p.y) for p in verts]
path = "M {} L {} z".format(coords[0], " L ".join(coords[1:]))
return (
'<path fill-rule="evenodd" fill="{2}" stroke="#555555" '
'stroke-width="{0}" opacity="0.6" d="{1}" />'
).format(2. * scale_factor, path, fill_color)
def _hashable_content(self):
D = {}
def ref_list(point_list):
kee = {}
for i, p in enumerate(ordered(set(point_list))):
kee[p] = i
D[i] = p
return [kee[p] for p in point_list]
S1 = ref_list(self.args)
r_nor = rotate_left(S1, least_rotation(S1))
S2 = ref_list(list(reversed(self.args)))
r_rev = rotate_left(S2, least_rotation(S2))
if r_nor < r_rev:
r = r_nor
else:
r = r_rev
canonical_args = [ D[order] for order in r ]
return tuple(canonical_args)
def __contains__(self, o):
"""
Return True if o is contained within the boundary lines of self.altitudes
Parameters
==========
other : GeometryEntity
Returns
=======
contained in : bool
The points (and sides, if applicable) are contained in self.
See Also
========
sympy.geometry.entity.GeometryEntity.encloses
Examples
========
>>> from sympy import Line, Segment, Point
>>> p = Point(0, 0)
>>> q = Point(1, 1)
>>> s = Segment(p, q*2)
>>> l = Line(p, q)
>>> p in q
False
>>> p in s
True
>>> q*3 in s
False
>>> s in l
True
"""
if isinstance(o, Polygon):
return self == o
elif isinstance(o, Segment):
return any(o in s for s in self.sides)
elif isinstance(o, Point):
if o in self.vertices:
return True
for side in self.sides:
if o in side:
return True
return False
def bisectors(p, prec=None):
"""Returns angle bisectors of a polygon. If prec is given
then approximate the point defining the ray to that precision.
The distance between the points defining the bisector ray is 1.
Examples
========
>>> from sympy import Polygon, Point
>>> p = Polygon(Point(0, 0), Point(2, 0), Point(1, 1), Point(0, 3))
>>> p.bisectors(2)
{Point2D(0, 0): Ray2D(Point2D(0, 0), Point2D(0.71, 0.71)),
Point2D(0, 3): Ray2D(Point2D(0, 3), Point2D(0.23, 2.0)),
Point2D(1, 1): Ray2D(Point2D(1, 1), Point2D(0.19, 0.42)),
Point2D(2, 0): Ray2D(Point2D(2, 0), Point2D(1.1, 0.38))}
"""
b = {}
pts = list(p.args)
pts.append(pts[0]) # close it
cw = Polygon._isright(*pts[:3])
if cw:
pts = list(reversed(pts))
for v, a in p.angles.items():
i = pts.index(v)
p1, p2 = Point._normalize_dimension(pts[i], pts[i + 1])
ray = Ray(p1, p2).rotate(a/2, v)
dir = ray.direction
ray = Ray(ray.p1, ray.p1 + dir/dir.distance((0, 0)))
if prec is not None:
ray = Ray(ray.p1, ray.p2.n(prec))
b[v] = ray
return b
class RegularPolygon(Polygon):
"""
A regular polygon.
Such a polygon has all internal angles equal and all sides the same length.
Parameters
==========
center : Point
radius : number or Basic instance
The distance from the center to a vertex
n : int
The number of sides
Attributes
==========
vertices
center
radius
rotation
apothem
interior_angle
exterior_angle
circumcircle
incircle
angles
Raises
======
GeometryError
If the `center` is not a Point, or the `radius` is not a number or Basic
instance, or the number of sides, `n`, is less than three.
Notes
=====
A RegularPolygon can be instantiated with Polygon with the kwarg n.
Regular polygons are instantiated with a center, radius, number of sides
and a rotation angle. Whereas the arguments of a Polygon are vertices, the
vertices of the RegularPolygon must be obtained with the vertices method.
See Also
========
sympy.geometry.point.Point, Polygon
Examples
========
>>> from sympy.geometry import RegularPolygon, Point
>>> r = RegularPolygon(Point(0, 0), 5, 3)
>>> r
RegularPolygon(Point2D(0, 0), 5, 3, 0)
>>> r.vertices[0]
Point2D(5, 0)
"""
__slots__ = ('_n', '_center', '_radius', '_rot')
def __new__(self, c, r, n, rot=0, **kwargs):
r, n, rot = map(sympify, (r, n, rot))
c = Point(c, dim=2, **kwargs)
if not isinstance(r, Expr):
raise GeometryError("r must be an Expr object, not %s" % r)
if n.is_Number:
as_int(n) # let an error raise if necessary
if n < 3:
raise GeometryError("n must be a >= 3, not %s" % n)
obj = GeometryEntity.__new__(self, c, r, n, **kwargs)
obj._n = n
obj._center = c
obj._radius = r
obj._rot = rot % (2*S.Pi/n) if rot.is_number else rot
return obj
@property
def args(self):
"""
Returns the center point, the radius,
the number of sides, and the orientation angle.
Examples
========
>>> from sympy import RegularPolygon, Point
>>> r = RegularPolygon(Point(0, 0), 5, 3)
>>> r.args
(Point2D(0, 0), 5, 3, 0)
"""
return self._center, self._radius, self._n, self._rot
def __str__(self):
return 'RegularPolygon(%s, %s, %s, %s)' % tuple(self.args)
def __repr__(self):
return 'RegularPolygon(%s, %s, %s, %s)' % tuple(self.args)
@property
def area(self):
"""Returns the area.
Examples
========
>>> from sympy.geometry import RegularPolygon
>>> square = RegularPolygon((0, 0), 1, 4)
>>> square.area
2
>>> _ == square.length**2
True
"""
c, r, n, rot = self.args
return sign(r)*n*self.length**2/(4*tan(pi/n))
@property
def length(self):
"""Returns the length of the sides.
The half-length of the side and the apothem form two legs
of a right triangle whose hypotenuse is the radius of the
regular polygon.
Examples
========
>>> from sympy.geometry import RegularPolygon
>>> from sympy import sqrt
>>> s = square_in_unit_circle = RegularPolygon((0, 0), 1, 4)
>>> s.length
sqrt(2)
>>> sqrt((_/2)**2 + s.apothem**2) == s.radius
True
"""
return self.radius*2*sin(pi/self._n)
@property
def center(self):
"""The center of the RegularPolygon
This is also the center of the circumscribing circle.
Returns
=======
center : Point
See Also
========
sympy.geometry.point.Point, sympy.geometry.ellipse.Ellipse.center
Examples
========
>>> from sympy.geometry import RegularPolygon, Point
>>> rp = RegularPolygon(Point(0, 0), 5, 4)
>>> rp.center
Point2D(0, 0)
"""
return self._center
centroid = center
@property
def circumcenter(self):
"""
Alias for center.
Examples
========
>>> from sympy.geometry import RegularPolygon, Point
>>> rp = RegularPolygon(Point(0, 0), 5, 4)
>>> rp.circumcenter
Point2D(0, 0)
"""
return self.center
@property
def radius(self):
"""Radius of the RegularPolygon
This is also the radius of the circumscribing circle.
Returns
=======
radius : number or instance of Basic
See Also
========
sympy.geometry.line.Segment.length, sympy.geometry.ellipse.Circle.radius
Examples
========
>>> from sympy import Symbol
>>> from sympy.geometry import RegularPolygon, Point
>>> radius = Symbol('r')
>>> rp = RegularPolygon(Point(0, 0), radius, 4)
>>> rp.radius
r
"""
return self._radius
@property
def circumradius(self):
"""
Alias for radius.
Examples
========
>>> from sympy import Symbol
>>> from sympy.geometry import RegularPolygon, Point
>>> radius = Symbol('r')
>>> rp = RegularPolygon(Point(0, 0), radius, 4)
>>> rp.circumradius
r
"""
return self.radius
@property
def rotation(self):
"""CCW angle by which the RegularPolygon is rotated
Returns
=======
rotation : number or instance of Basic
Examples
========
>>> from sympy import pi
>>> from sympy.abc import a
>>> from sympy.geometry import RegularPolygon, Point
>>> RegularPolygon(Point(0, 0), 3, 4, pi/4).rotation
pi/4
Numerical rotation angles are made canonical:
>>> RegularPolygon(Point(0, 0), 3, 4, a).rotation
a
>>> RegularPolygon(Point(0, 0), 3, 4, pi).rotation
0
"""
return self._rot
@property
def apothem(self):
"""The inradius of the RegularPolygon.
The apothem/inradius is the radius of the inscribed circle.
Returns
=======
apothem : number or instance of Basic
See Also
========
sympy.geometry.line.Segment.length, sympy.geometry.ellipse.Circle.radius
Examples
========
>>> from sympy import Symbol
>>> from sympy.geometry import RegularPolygon, Point
>>> radius = Symbol('r')
>>> rp = RegularPolygon(Point(0, 0), radius, 4)
>>> rp.apothem
sqrt(2)*r/2
"""
return self.radius * cos(S.Pi/self._n)
@property
def inradius(self):
"""
Alias for apothem.
Examples
========
>>> from sympy import Symbol
>>> from sympy.geometry import RegularPolygon, Point
>>> radius = Symbol('r')
>>> rp = RegularPolygon(Point(0, 0), radius, 4)
>>> rp.inradius
sqrt(2)*r/2
"""
return self.apothem
@property
def interior_angle(self):
"""Measure of the interior angles.
Returns
=======
interior_angle : number
See Also
========
sympy.geometry.line.LinearEntity.angle_between
Examples
========
>>> from sympy.geometry import RegularPolygon, Point
>>> rp = RegularPolygon(Point(0, 0), 4, 8)
>>> rp.interior_angle
3*pi/4
"""
return (self._n - 2)*S.Pi/self._n
@property
def exterior_angle(self):
"""Measure of the exterior angles.
Returns
=======
exterior_angle : number
See Also
========
sympy.geometry.line.LinearEntity.angle_between
Examples
========
>>> from sympy.geometry import RegularPolygon, Point
>>> rp = RegularPolygon(Point(0, 0), 4, 8)
>>> rp.exterior_angle
pi/4
"""
return 2*S.Pi/self._n
@property
def circumcircle(self):
"""The circumcircle of the RegularPolygon.
Returns
=======
circumcircle : Circle
See Also
========
circumcenter, sympy.geometry.ellipse.Circle
Examples
========
>>> from sympy.geometry import RegularPolygon, Point
>>> rp = RegularPolygon(Point(0, 0), 4, 8)
>>> rp.circumcircle
Circle(Point2D(0, 0), 4)
"""
return Circle(self.center, self.radius)
@property
def incircle(self):
"""The incircle of the RegularPolygon.
Returns
=======
incircle : Circle
See Also
========
inradius, sympy.geometry.ellipse.Circle
Examples
========
>>> from sympy.geometry import RegularPolygon, Point
>>> rp = RegularPolygon(Point(0, 0), 4, 7)
>>> rp.incircle
Circle(Point2D(0, 0), 4*cos(pi/7))
"""
return Circle(self.center, self.apothem)
@property
def angles(self):
"""
Returns a dictionary with keys, the vertices of the Polygon,
and values, the interior angle at each vertex.
Examples
========
>>> from sympy import RegularPolygon, Point
>>> r = RegularPolygon(Point(0, 0), 5, 3)
>>> r.angles
{Point2D(-5/2, -5*sqrt(3)/2): pi/3,
Point2D(-5/2, 5*sqrt(3)/2): pi/3,
Point2D(5, 0): pi/3}
"""
ret = {}
ang = self.interior_angle
for v in self.vertices:
ret[v] = ang
return ret
def encloses_point(self, p):
"""
Return True if p is enclosed by (is inside of) self.
Notes
=====
Being on the border of self is considered False.
The general Polygon.encloses_point method is called only if
a point is not within or beyond the incircle or circumcircle,
respectively.
Parameters
==========
p : Point
Returns
=======
encloses_point : True, False or None
See Also
========
sympy.geometry.ellipse.Ellipse.encloses_point
Examples
========
>>> from sympy import RegularPolygon, S, Point, Symbol
>>> p = RegularPolygon((0, 0), 3, 4)
>>> p.encloses_point(Point(0, 0))
True
>>> r, R = p.inradius, p.circumradius
>>> p.encloses_point(Point((r + R)/2, 0))
True
>>> p.encloses_point(Point(R/2, R/2 + (R - r)/10))
False
>>> t = Symbol('t', real=True)
>>> p.encloses_point(p.arbitrary_point().subs(t, S.Half))
False
>>> p.encloses_point(Point(5, 5))
False
"""
c = self.center
d = Segment(c, p).length
if d >= self.radius:
return False
elif d < self.inradius:
return True
else:
# now enumerate the RegularPolygon like a general polygon.
return Polygon.encloses_point(self, p)
def spin(self, angle):
"""Increment *in place* the virtual Polygon's rotation by ccw angle.
See also: rotate method which moves the center.
>>> from sympy import Polygon, Point, pi
>>> r = Polygon(Point(0,0), 1, n=3)
>>> r.vertices[0]
Point2D(1, 0)
>>> r.spin(pi/6)
>>> r.vertices[0]
Point2D(sqrt(3)/2, 1/2)
See Also
========
rotation
rotate : Creates a copy of the RegularPolygon rotated about a Point
"""
self._rot += angle
def rotate(self, angle, pt=None):
"""Override GeometryEntity.rotate to first rotate the RegularPolygon
about its center.
>>> from sympy import Point, RegularPolygon, pi
>>> t = RegularPolygon(Point(1, 0), 1, 3)
>>> t.vertices[0] # vertex on x-axis
Point2D(2, 0)
>>> t.rotate(pi/2).vertices[0] # vertex on y axis now
Point2D(0, 2)
See Also
========
rotation
spin : Rotates a RegularPolygon in place
"""
r = type(self)(*self.args) # need a copy or else changes are in-place
r._rot += angle
return GeometryEntity.rotate(r, angle, pt)
def scale(self, x=1, y=1, pt=None):
"""Override GeometryEntity.scale since it is the radius that must be
scaled (if x == y) or else a new Polygon must be returned.
>>> from sympy import RegularPolygon
Symmetric scaling returns a RegularPolygon:
>>> RegularPolygon((0, 0), 1, 4).scale(2, 2)
RegularPolygon(Point2D(0, 0), 2, 4, 0)
Asymmetric scaling returns a kite as a Polygon:
>>> RegularPolygon((0, 0), 1, 4).scale(2, 1)
Polygon(Point2D(2, 0), Point2D(0, 1), Point2D(-2, 0), Point2D(0, -1))
"""
if pt:
pt = Point(pt, dim=2)
return self.translate(*(-pt).args).scale(x, y).translate(*pt.args)
if x != y:
return Polygon(*self.vertices).scale(x, y)
c, r, n, rot = self.args
r *= x
return self.func(c, r, n, rot)
def reflect(self, line):
"""Override GeometryEntity.reflect since this is not made of only
points.
Examples
========
>>> from sympy import RegularPolygon, Line
>>> RegularPolygon((0, 0), 1, 4).reflect(Line((0, 1), slope=-2))
RegularPolygon(Point2D(4/5, 2/5), -1, 4, atan(4/3))
"""
c, r, n, rot = self.args
v = self.vertices[0]
d = v - c
cc = c.reflect(line)
vv = v.reflect(line)
dd = vv - cc
# calculate rotation about the new center
# which will align the vertices
l1 = Ray((0, 0), dd)
l2 = Ray((0, 0), d)
ang = l1.closing_angle(l2)
rot += ang
# change sign of radius as point traversal is reversed
return self.func(cc, -r, n, rot)
@property
def vertices(self):
"""The vertices of the RegularPolygon.
Returns
=======
vertices : list
Each vertex is a Point.
See Also
========
sympy.geometry.point.Point
Examples
========
>>> from sympy.geometry import RegularPolygon, Point
>>> rp = RegularPolygon(Point(0, 0), 5, 4)
>>> rp.vertices
[Point2D(5, 0), Point2D(0, 5), Point2D(-5, 0), Point2D(0, -5)]
"""
c = self._center
r = abs(self._radius)
rot = self._rot
v = 2*S.Pi/self._n
return [Point(c.x + r*cos(k*v + rot), c.y + r*sin(k*v + rot))
for k in range(self._n)]
def __eq__(self, o):
if not isinstance(o, Polygon):
return False
elif not isinstance(o, RegularPolygon):
return Polygon.__eq__(o, self)
return self.args == o.args
def __hash__(self):
return super().__hash__()
class Triangle(Polygon):
"""
A polygon with three vertices and three sides.
Parameters
==========
points : sequence of Points
keyword: asa, sas, or sss to specify sides/angles of the triangle
Attributes
==========
vertices
altitudes
orthocenter
circumcenter
circumradius
circumcircle
inradius
incircle
exradii
medians
medial
nine_point_circle
Raises
======
GeometryError
If the number of vertices is not equal to three, or one of the vertices
is not a Point, or a valid keyword is not given.
See Also
========
sympy.geometry.point.Point, Polygon
Examples
========
>>> from sympy.geometry import Triangle, Point
>>> Triangle(Point(0, 0), Point(4, 0), Point(4, 3))
Triangle(Point2D(0, 0), Point2D(4, 0), Point2D(4, 3))
Keywords sss, sas, or asa can be used to give the desired
side lengths (in order) and interior angles (in degrees) that
define the triangle:
>>> Triangle(sss=(3, 4, 5))
Triangle(Point2D(0, 0), Point2D(3, 0), Point2D(3, 4))
>>> Triangle(asa=(30, 1, 30))
Triangle(Point2D(0, 0), Point2D(1, 0), Point2D(1/2, sqrt(3)/6))
>>> Triangle(sas=(1, 45, 2))
Triangle(Point2D(0, 0), Point2D(2, 0), Point2D(sqrt(2)/2, sqrt(2)/2))
"""
def __new__(cls, *args, **kwargs):
if len(args) != 3:
if 'sss' in kwargs:
return _sss(*[simplify(a) for a in kwargs['sss']])
if 'asa' in kwargs:
return _asa(*[simplify(a) for a in kwargs['asa']])
if 'sas' in kwargs:
return _sas(*[simplify(a) for a in kwargs['sas']])
msg = "Triangle instantiates with three points or a valid keyword."
raise GeometryError(msg)
vertices = [Point(a, dim=2, **kwargs) for a in args]
# remove consecutive duplicates
nodup = []
for p in vertices:
if nodup and p == nodup[-1]:
continue
nodup.append(p)
if len(nodup) > 1 and nodup[-1] == nodup[0]:
nodup.pop() # last point was same as first
# remove collinear points
i = -3
while i < len(nodup) - 3 and len(nodup) > 2:
a, b, c = sorted(
[nodup[i], nodup[i + 1], nodup[i + 2]], key=default_sort_key)
if Point.is_collinear(a, b, c):
nodup[i] = a
nodup[i + 1] = None
nodup.pop(i + 1)
i += 1
vertices = list(filter(lambda x: x is not None, nodup))
if len(vertices) == 3:
return GeometryEntity.__new__(cls, *vertices, **kwargs)
elif len(vertices) == 2:
return Segment(*vertices, **kwargs)
else:
return Point(*vertices, **kwargs)
@property
def vertices(self):
"""The triangle's vertices
Returns
=======
vertices : tuple
Each element in the tuple is a Point
See Also
========
sympy.geometry.point.Point
Examples
========
>>> from sympy.geometry import Triangle, Point
>>> t = Triangle(Point(0, 0), Point(4, 0), Point(4, 3))
>>> t.vertices
(Point2D(0, 0), Point2D(4, 0), Point2D(4, 3))
"""
return self.args
def is_similar(t1, t2):
"""Is another triangle similar to this one.
Two triangles are similar if one can be uniformly scaled to the other.
Parameters
==========
other: Triangle
Returns
=======
is_similar : boolean
See Also
========
sympy.geometry.entity.GeometryEntity.is_similar
Examples
========
>>> from sympy.geometry import Triangle, Point
>>> t1 = Triangle(Point(0, 0), Point(4, 0), Point(4, 3))
>>> t2 = Triangle(Point(0, 0), Point(-4, 0), Point(-4, -3))
>>> t1.is_similar(t2)
True
>>> t2 = Triangle(Point(0, 0), Point(-4, 0), Point(-4, -4))
>>> t1.is_similar(t2)
False
"""
if not isinstance(t2, Polygon):
return False
s1_1, s1_2, s1_3 = [side.length for side in t1.sides]
s2 = [side.length for side in t2.sides]
def _are_similar(u1, u2, u3, v1, v2, v3):
e1 = simplify(u1/v1)
e2 = simplify(u2/v2)
e3 = simplify(u3/v3)
return bool(e1 == e2) and bool(e2 == e3)
# There's only 6 permutations, so write them out
return _are_similar(s1_1, s1_2, s1_3, *s2) or \
_are_similar(s1_1, s1_3, s1_2, *s2) or \
_are_similar(s1_2, s1_1, s1_3, *s2) or \
_are_similar(s1_2, s1_3, s1_1, *s2) or \
_are_similar(s1_3, s1_1, s1_2, *s2) or \
_are_similar(s1_3, s1_2, s1_1, *s2)
def is_equilateral(self):
"""Are all the sides the same length?
Returns
=======
is_equilateral : boolean
See Also
========
sympy.geometry.entity.GeometryEntity.is_similar, RegularPolygon
is_isosceles, is_right, is_scalene
Examples
========
>>> from sympy.geometry import Triangle, Point
>>> t1 = Triangle(Point(0, 0), Point(4, 0), Point(4, 3))
>>> t1.is_equilateral()
False
>>> from sympy import sqrt
>>> t2 = Triangle(Point(0, 0), Point(10, 0), Point(5, 5*sqrt(3)))
>>> t2.is_equilateral()
True
"""
return not has_variety(s.length for s in self.sides)
def is_isosceles(self):
"""Are two or more of the sides the same length?
Returns
=======
is_isosceles : boolean
See Also
========
is_equilateral, is_right, is_scalene
Examples
========
>>> from sympy.geometry import Triangle, Point
>>> t1 = Triangle(Point(0, 0), Point(4, 0), Point(2, 4))
>>> t1.is_isosceles()
True
"""
return has_dups(s.length for s in self.sides)
def is_scalene(self):
"""Are all the sides of the triangle of different lengths?
Returns
=======
is_scalene : boolean
See Also
========
is_equilateral, is_isosceles, is_right
Examples
========
>>> from sympy.geometry import Triangle, Point
>>> t1 = Triangle(Point(0, 0), Point(4, 0), Point(1, 4))
>>> t1.is_scalene()
True
"""
return not has_dups(s.length for s in self.sides)
def is_right(self):
"""Is the triangle right-angled.
Returns
=======
is_right : boolean
See Also
========
sympy.geometry.line.LinearEntity.is_perpendicular
is_equilateral, is_isosceles, is_scalene
Examples
========
>>> from sympy.geometry import Triangle, Point
>>> t1 = Triangle(Point(0, 0), Point(4, 0), Point(4, 3))
>>> t1.is_right()
True
"""
s = self.sides
return Segment.is_perpendicular(s[0], s[1]) or \
Segment.is_perpendicular(s[1], s[2]) or \
Segment.is_perpendicular(s[0], s[2])
@property
def altitudes(self):
"""The altitudes of the triangle.
An altitude of a triangle is a segment through a vertex,
perpendicular to the opposite side, with length being the
height of the vertex measured from the line containing the side.
Returns
=======
altitudes : dict
The dictionary consists of keys which are vertices and values
which are Segments.
See Also
========
sympy.geometry.point.Point, sympy.geometry.line.Segment.length
Examples
========
>>> from sympy.geometry import Point, Triangle
>>> p1, p2, p3 = Point(0, 0), Point(1, 0), Point(0, 1)
>>> t = Triangle(p1, p2, p3)
>>> t.altitudes[p1]
Segment2D(Point2D(0, 0), Point2D(1/2, 1/2))
"""
s = self.sides
v = self.vertices
return {v[0]: s[1].perpendicular_segment(v[0]),
v[1]: s[2].perpendicular_segment(v[1]),
v[2]: s[0].perpendicular_segment(v[2])}
@property
def orthocenter(self):
"""The orthocenter of the triangle.
The orthocenter is the intersection of the altitudes of a triangle.
It may lie inside, outside or on the triangle.
Returns
=======
orthocenter : Point
See Also
========
sympy.geometry.point.Point
Examples
========
>>> from sympy.geometry import Point, Triangle
>>> p1, p2, p3 = Point(0, 0), Point(1, 0), Point(0, 1)
>>> t = Triangle(p1, p2, p3)
>>> t.orthocenter
Point2D(0, 0)
"""
a = self.altitudes
v = self.vertices
return Line(a[v[0]]).intersection(Line(a[v[1]]))[0]
@property
def circumcenter(self):
"""The circumcenter of the triangle
The circumcenter is the center of the circumcircle.
Returns
=======
circumcenter : Point
See Also
========
sympy.geometry.point.Point
Examples
========
>>> from sympy.geometry import Point, Triangle
>>> p1, p2, p3 = Point(0, 0), Point(1, 0), Point(0, 1)
>>> t = Triangle(p1, p2, p3)
>>> t.circumcenter
Point2D(1/2, 1/2)
"""
a, b, c = [x.perpendicular_bisector() for x in self.sides]
if not a.intersection(b):
print(a,b,a.intersection(b))
return a.intersection(b)[0]
@property
def circumradius(self):
"""The radius of the circumcircle of the triangle.
Returns
=======
circumradius : number of Basic instance
See Also
========
sympy.geometry.ellipse.Circle.radius
Examples
========
>>> from sympy import Symbol
>>> from sympy.geometry import Point, Triangle
>>> a = Symbol('a')
>>> p1, p2, p3 = Point(0, 0), Point(1, 0), Point(0, a)
>>> t = Triangle(p1, p2, p3)
>>> t.circumradius
sqrt(a**2/4 + 1/4)
"""
return Point.distance(self.circumcenter, self.vertices[0])
@property
def circumcircle(self):
"""The circle which passes through the three vertices of the triangle.
Returns
=======
circumcircle : Circle
See Also
========
sympy.geometry.ellipse.Circle
Examples
========
>>> from sympy.geometry import Point, Triangle
>>> p1, p2, p3 = Point(0, 0), Point(1, 0), Point(0, 1)
>>> t = Triangle(p1, p2, p3)
>>> t.circumcircle
Circle(Point2D(1/2, 1/2), sqrt(2)/2)
"""
return Circle(self.circumcenter, self.circumradius)
def bisectors(self):
"""The angle bisectors of the triangle.
An angle bisector of a triangle is a straight line through a vertex
which cuts the corresponding angle in half.
Returns
=======
bisectors : dict
Each key is a vertex (Point) and each value is the corresponding
bisector (Segment).
See Also
========
sympy.geometry.point.Point, sympy.geometry.line.Segment
Examples
========
>>> from sympy.geometry import Point, Triangle, Segment
>>> p1, p2, p3 = Point(0, 0), Point(1, 0), Point(0, 1)
>>> t = Triangle(p1, p2, p3)
>>> from sympy import sqrt
>>> t.bisectors()[p2] == Segment(Point(1, 0), Point(0, sqrt(2) - 1))
True
"""
# use lines containing sides so containment check during
# intersection calculation can be avoided, thus reducing
# the processing time for calculating the bisectors
s = [Line(l) for l in self.sides]
v = self.vertices
c = self.incenter
l1 = Segment(v[0], Line(v[0], c).intersection(s[1])[0])
l2 = Segment(v[1], Line(v[1], c).intersection(s[2])[0])
l3 = Segment(v[2], Line(v[2], c).intersection(s[0])[0])
return {v[0]: l1, v[1]: l2, v[2]: l3}
@property
def incenter(self):
"""The center of the incircle.
The incircle is the circle which lies inside the triangle and touches
all three sides.
Returns
=======
incenter : Point
See Also
========
incircle, sympy.geometry.point.Point
Examples
========
>>> from sympy.geometry import Point, Triangle
>>> p1, p2, p3 = Point(0, 0), Point(1, 0), Point(0, 1)
>>> t = Triangle(p1, p2, p3)
>>> t.incenter
Point2D(1 - sqrt(2)/2, 1 - sqrt(2)/2)
"""
s = self.sides
l = Matrix([s[i].length for i in [1, 2, 0]])
p = sum(l)
v = self.vertices
x = simplify(l.dot(Matrix([vi.x for vi in v]))/p)
y = simplify(l.dot(Matrix([vi.y for vi in v]))/p)
return Point(x, y)
@property
def inradius(self):
"""The radius of the incircle.
Returns
=======
inradius : number of Basic instance
See Also
========
incircle, sympy.geometry.ellipse.Circle.radius
Examples
========
>>> from sympy.geometry import Point, Triangle
>>> p1, p2, p3 = Point(0, 0), Point(4, 0), Point(0, 3)
>>> t = Triangle(p1, p2, p3)
>>> t.inradius
1
"""
return simplify(2 * self.area / self.perimeter)
@property
def incircle(self):
"""The incircle of the triangle.
The incircle is the circle which lies inside the triangle and touches
all three sides.
Returns
=======
incircle : Circle
See Also
========
sympy.geometry.ellipse.Circle
Examples
========
>>> from sympy.geometry import Point, Triangle
>>> p1, p2, p3 = Point(0, 0), Point(2, 0), Point(0, 2)
>>> t = Triangle(p1, p2, p3)
>>> t.incircle
Circle(Point2D(2 - sqrt(2), 2 - sqrt(2)), 2 - sqrt(2))
"""
return Circle(self.incenter, self.inradius)
@property
def exradii(self):
"""The radius of excircles of a triangle.
An excircle of the triangle is a circle lying outside the triangle,
tangent to one of its sides and tangent to the extensions of the
other two.
Returns
=======
exradii : dict
See Also
========
sympy.geometry.polygon.Triangle.inradius
Examples
========
The exradius touches the side of the triangle to which it is keyed, e.g.
the exradius touching side 2 is:
>>> from sympy.geometry import Point, Triangle
>>> p1, p2, p3 = Point(0, 0), Point(6, 0), Point(0, 2)
>>> t = Triangle(p1, p2, p3)
>>> t.exradii[t.sides[2]]
-2 + sqrt(10)
References
==========
[1] http://mathworld.wolfram.com/Exradius.html
[2] http://mathworld.wolfram.com/Excircles.html
"""
side = self.sides
a = side[0].length
b = side[1].length
c = side[2].length
s = (a+b+c)/2
area = self.area
exradii = {self.sides[0]: simplify(area/(s-a)),
self.sides[1]: simplify(area/(s-b)),
self.sides[2]: simplify(area/(s-c))}
return exradii
@property
def excenters(self):
"""Excenters of the triangle.
An excenter is the center of a circle that is tangent to a side of the
triangle and the extensions of the other two sides.
Returns
=======
excenters : dict
Examples
========
The excenters are keyed to the side of the triangle to which their corresponding
excircle is tangent: The center is keyed, e.g. the excenter of a circle touching
side 0 is:
>>> from sympy.geometry import Point, Triangle
>>> p1, p2, p3 = Point(0, 0), Point(6, 0), Point(0, 2)
>>> t = Triangle(p1, p2, p3)
>>> t.excenters[t.sides[0]]
Point2D(12*sqrt(10), 2/3 + sqrt(10)/3)
See Also
========
sympy.geometry.polygon.Triangle.exradii
References
==========
.. [1] http://mathworld.wolfram.com/Excircles.html
"""
s = self.sides
v = self.vertices
a = s[0].length
b = s[1].length
c = s[2].length
x = [v[0].x, v[1].x, v[2].x]
y = [v[0].y, v[1].y, v[2].y]
exc_coords = {
"x1": simplify(-a*x[0]+b*x[1]+c*x[2]/(-a+b+c)),
"x2": simplify(a*x[0]-b*x[1]+c*x[2]/(a-b+c)),
"x3": simplify(a*x[0]+b*x[1]-c*x[2]/(a+b-c)),
"y1": simplify(-a*y[0]+b*y[1]+c*y[2]/(-a+b+c)),
"y2": simplify(a*y[0]-b*y[1]+c*y[2]/(a-b+c)),
"y3": simplify(a*y[0]+b*y[1]-c*y[2]/(a+b-c))
}
excenters = {
s[0]: Point(exc_coords["x1"], exc_coords["y1"]),
s[1]: Point(exc_coords["x2"], exc_coords["y2"]),
s[2]: Point(exc_coords["x3"], exc_coords["y3"])
}
return excenters
@property
def medians(self):
"""The medians of the triangle.
A median of a triangle is a straight line through a vertex and the
midpoint of the opposite side, and divides the triangle into two
equal areas.
Returns
=======
medians : dict
Each key is a vertex (Point) and each value is the median (Segment)
at that point.
See Also
========
sympy.geometry.point.Point.midpoint, sympy.geometry.line.Segment.midpoint
Examples
========
>>> from sympy.geometry import Point, Triangle
>>> p1, p2, p3 = Point(0, 0), Point(1, 0), Point(0, 1)
>>> t = Triangle(p1, p2, p3)
>>> t.medians[p1]
Segment2D(Point2D(0, 0), Point2D(1/2, 1/2))
"""
s = self.sides
v = self.vertices
return {v[0]: Segment(v[0], s[1].midpoint),
v[1]: Segment(v[1], s[2].midpoint),
v[2]: Segment(v[2], s[0].midpoint)}
@property
def medial(self):
"""The medial triangle of the triangle.
The triangle which is formed from the midpoints of the three sides.
Returns
=======
medial : Triangle
See Also
========
sympy.geometry.line.Segment.midpoint
Examples
========
>>> from sympy.geometry import Point, Triangle
>>> p1, p2, p3 = Point(0, 0), Point(1, 0), Point(0, 1)
>>> t = Triangle(p1, p2, p3)
>>> t.medial
Triangle(Point2D(1/2, 0), Point2D(1/2, 1/2), Point2D(0, 1/2))
"""
s = self.sides
return Triangle(s[0].midpoint, s[1].midpoint, s[2].midpoint)
@property
def nine_point_circle(self):
"""The nine-point circle of the triangle.
Nine-point circle is the circumcircle of the medial triangle, which
passes through the feet of altitudes and the middle points of segments
connecting the vertices and the orthocenter.
Returns
=======
nine_point_circle : Circle
See also
========
sympy.geometry.line.Segment.midpoint
sympy.geometry.polygon.Triangle.medial
sympy.geometry.polygon.Triangle.orthocenter
Examples
========
>>> from sympy.geometry import Point, Triangle
>>> p1, p2, p3 = Point(0, 0), Point(1, 0), Point(0, 1)
>>> t = Triangle(p1, p2, p3)
>>> t.nine_point_circle
Circle(Point2D(1/4, 1/4), sqrt(2)/4)
"""
return Circle(*self.medial.vertices)
@property
def eulerline(self):
"""The Euler line of the triangle.
The line which passes through circumcenter, centroid and orthocenter.
Returns
=======
eulerline : Line (or Point for equilateral triangles in which case all
centers coincide)
Examples
========
>>> from sympy.geometry import Point, Triangle
>>> p1, p2, p3 = Point(0, 0), Point(1, 0), Point(0, 1)
>>> t = Triangle(p1, p2, p3)
>>> t.eulerline
Line2D(Point2D(0, 0), Point2D(1/2, 1/2))
"""
if self.is_equilateral():
return self.orthocenter
return Line(self.orthocenter, self.circumcenter)
def rad(d):
"""Return the radian value for the given degrees (pi = 180 degrees)."""
return d*pi/180
def deg(r):
"""Return the degree value for the given radians (pi = 180 degrees)."""
return r/pi*180
def _slope(d):
rv = tan(rad(d))
return rv
def _asa(d1, l, d2):
"""Return triangle having side with length l on the x-axis."""
xy = Line((0, 0), slope=_slope(d1)).intersection(
Line((l, 0), slope=_slope(180 - d2)))[0]
return Triangle((0, 0), (l, 0), xy)
def _sss(l1, l2, l3):
"""Return triangle having side of length l1 on the x-axis."""
c1 = Circle((0, 0), l3)
c2 = Circle((l1, 0), l2)
inter = [a for a in c1.intersection(c2) if a.y.is_nonnegative]
if not inter:
return None
pt = inter[0]
return Triangle((0, 0), (l1, 0), pt)
def _sas(l1, d, l2):
"""Return triangle having side with length l2 on the x-axis."""
p1 = Point(0, 0)
p2 = Point(l2, 0)
p3 = Point(cos(rad(d))*l1, sin(rad(d))*l1)
return Triangle(p1, p2, p3)
|
43a1773e85c272bdd38edf54acf77fb78f2824309ec34fde78d4e200696d6426 | """
This module implements Holonomic Functions and
various operations on them.
"""
from sympy import (Symbol, S, Dummy, Order, rf, I,
solve, limit, Float, nsimplify, gamma)
from sympy.core.compatibility import ordered
from sympy.core.numbers import NaN, Infinity, NegativeInfinity
from sympy.core.sympify import sympify
from sympy.functions.combinatorial.factorials import binomial, factorial
from sympy.functions.elementary.exponential import exp_polar, exp
from sympy.functions.special.hyper import hyper, meijerg
from sympy.integrals import meijerint
from sympy.matrices import Matrix
from sympy.polys.rings import PolyElement
from sympy.polys.fields import FracElement
from sympy.polys.domains import QQ, RR
from sympy.polys.polyclasses import DMF
from sympy.polys.polyroots import roots
from sympy.polys.polytools import Poly
from sympy.polys.matrices import DomainMatrix
from sympy.printing import sstr
from sympy.simplify.hyperexpand import hyperexpand
from .recurrence import HolonomicSequence, RecurrenceOperator, RecurrenceOperators
from .holonomicerrors import (NotPowerSeriesError, NotHyperSeriesError,
SingularityError, NotHolonomicError)
def _find_nonzero_solution(r, homosys):
ones = lambda shape: DomainMatrix.ones(shape, r.domain)
particular, nullspace = r._solve(homosys)
nullity = nullspace.shape[0]
nullpart = ones((1, nullity)) * nullspace
sol = (particular + nullpart).transpose()
return sol
def DifferentialOperators(base, generator):
r"""
This function is used to create annihilators using ``Dx``.
Explanation
===========
Returns an Algebra of Differential Operators also called Weyl Algebra
and the operator for differentiation i.e. the ``Dx`` operator.
Parameters
==========
base:
Base polynomial ring for the algebra.
The base polynomial ring is the ring of polynomials in :math:`x` that
will appear as coefficients in the operators.
generator:
Generator of the algebra which can
be either a noncommutative ``Symbol`` or a string. e.g. "Dx" or "D".
Examples
========
>>> from sympy.polys.domains import ZZ
>>> from sympy.abc import x
>>> from sympy.holonomic.holonomic import DifferentialOperators
>>> R, Dx = DifferentialOperators(ZZ.old_poly_ring(x), 'Dx')
>>> R
Univariate Differential Operator Algebra in intermediate Dx over the base ring ZZ[x]
>>> Dx*x
(1) + (x)*Dx
"""
ring = DifferentialOperatorAlgebra(base, generator)
return (ring, ring.derivative_operator)
class DifferentialOperatorAlgebra:
r"""
An Ore Algebra is a set of noncommutative polynomials in the
intermediate ``Dx`` and coefficients in a base polynomial ring :math:`A`.
It follows the commutation rule:
.. math ::
Dxa = \sigma(a)Dx + \delta(a)
for :math:`a \subset A`.
Where :math:`\sigma: A \Rightarrow A` is an endomorphism and :math:`\delta: A \rightarrow A`
is a skew-derivation i.e. :math:`\delta(ab) = \delta(a) b + \sigma(a) \delta(b)`.
If one takes the sigma as identity map and delta as the standard derivation
then it becomes the algebra of Differential Operators also called
a Weyl Algebra i.e. an algebra whose elements are Differential Operators.
This class represents a Weyl Algebra and serves as the parent ring for
Differential Operators.
Examples
========
>>> from sympy.polys.domains import ZZ
>>> from sympy import symbols
>>> from sympy.holonomic.holonomic import DifferentialOperators
>>> x = symbols('x')
>>> R, Dx = DifferentialOperators(ZZ.old_poly_ring(x), 'Dx')
>>> R
Univariate Differential Operator Algebra in intermediate Dx over the base ring
ZZ[x]
See Also
========
DifferentialOperator
"""
def __init__(self, base, generator):
# the base polynomial ring for the algebra
self.base = base
# the operator representing differentiation i.e. `Dx`
self.derivative_operator = DifferentialOperator(
[base.zero, base.one], self)
if generator is None:
self.gen_symbol = Symbol('Dx', commutative=False)
else:
if isinstance(generator, str):
self.gen_symbol = Symbol(generator, commutative=False)
elif isinstance(generator, Symbol):
self.gen_symbol = generator
def __str__(self):
string = 'Univariate Differential Operator Algebra in intermediate '\
+ sstr(self.gen_symbol) + ' over the base ring ' + \
(self.base).__str__()
return string
__repr__ = __str__
def __eq__(self, other):
if self.base == other.base and self.gen_symbol == other.gen_symbol:
return True
else:
return False
class DifferentialOperator:
"""
Differential Operators are elements of Weyl Algebra. The Operators
are defined by a list of polynomials in the base ring and the
parent ring of the Operator i.e. the algebra it belongs to.
Explanation
===========
Takes a list of polynomials for each power of ``Dx`` and the
parent ring which must be an instance of DifferentialOperatorAlgebra.
A Differential Operator can be created easily using
the operator ``Dx``. See examples below.
Examples
========
>>> from sympy.holonomic.holonomic import DifferentialOperator, DifferentialOperators
>>> from sympy.polys.domains import ZZ
>>> from sympy import symbols
>>> x = symbols('x')
>>> R, Dx = DifferentialOperators(ZZ.old_poly_ring(x),'Dx')
>>> DifferentialOperator([0, 1, x**2], R)
(1)*Dx + (x**2)*Dx**2
>>> (x*Dx*x + 1 - Dx**2)**2
(2*x**2 + 2*x + 1) + (4*x**3 + 2*x**2 - 4)*Dx + (x**4 - 6*x - 2)*Dx**2 + (-2*x**2)*Dx**3 + (1)*Dx**4
See Also
========
DifferentialOperatorAlgebra
"""
_op_priority = 20
def __init__(self, list_of_poly, parent):
"""
Parameters
==========
list_of_poly:
List of polynomials belonging to the base ring of the algebra.
parent:
Parent algebra of the operator.
"""
# the parent ring for this operator
# must be an DifferentialOperatorAlgebra object
self.parent = parent
base = self.parent.base
self.x = base.gens[0] if isinstance(base.gens[0], Symbol) else base.gens[0][0]
# sequence of polynomials in x for each power of Dx
# the list should not have trailing zeroes
# represents the operator
# convert the expressions into ring elements using from_sympy
for i, j in enumerate(list_of_poly):
if not isinstance(j, base.dtype):
list_of_poly[i] = base.from_sympy(sympify(j))
else:
list_of_poly[i] = base.from_sympy(base.to_sympy(j))
self.listofpoly = list_of_poly
# highest power of `Dx`
self.order = len(self.listofpoly) - 1
def __mul__(self, other):
"""
Multiplies two DifferentialOperator and returns another
DifferentialOperator instance using the commutation rule
Dx*a = a*Dx + a'
"""
listofself = self.listofpoly
if not isinstance(other, DifferentialOperator):
if not isinstance(other, self.parent.base.dtype):
listofother = [self.parent.base.from_sympy(sympify(other))]
else:
listofother = [other]
else:
listofother = other.listofpoly
# multiplies a polynomial `b` with a list of polynomials
def _mul_dmp_diffop(b, listofother):
if isinstance(listofother, list):
sol = []
for i in listofother:
sol.append(i * b)
return sol
else:
return [b * listofother]
sol = _mul_dmp_diffop(listofself[0], listofother)
# compute Dx^i * b
def _mul_Dxi_b(b):
sol1 = [self.parent.base.zero]
sol2 = []
if isinstance(b, list):
for i in b:
sol1.append(i)
sol2.append(i.diff())
else:
sol1.append(self.parent.base.from_sympy(b))
sol2.append(self.parent.base.from_sympy(b).diff())
return _add_lists(sol1, sol2)
for i in range(1, len(listofself)):
# find Dx^i * b in ith iteration
listofother = _mul_Dxi_b(listofother)
# solution = solution + listofself[i] * (Dx^i * b)
sol = _add_lists(sol, _mul_dmp_diffop(listofself[i], listofother))
return DifferentialOperator(sol, self.parent)
def __rmul__(self, other):
if not isinstance(other, DifferentialOperator):
if not isinstance(other, self.parent.base.dtype):
other = (self.parent.base).from_sympy(sympify(other))
sol = []
for j in self.listofpoly:
sol.append(other * j)
return DifferentialOperator(sol, self.parent)
def __add__(self, other):
if isinstance(other, DifferentialOperator):
sol = _add_lists(self.listofpoly, other.listofpoly)
return DifferentialOperator(sol, self.parent)
else:
list_self = self.listofpoly
if not isinstance(other, self.parent.base.dtype):
list_other = [((self.parent).base).from_sympy(sympify(other))]
else:
list_other = [other]
sol = []
sol.append(list_self[0] + list_other[0])
sol += list_self[1:]
return DifferentialOperator(sol, self.parent)
__radd__ = __add__
def __sub__(self, other):
return self + (-1) * other
def __rsub__(self, other):
return (-1) * self + other
def __neg__(self):
return -1 * self
def __truediv__(self, other):
return self * (S.One / other)
def __pow__(self, n):
if n == 1:
return self
if n == 0:
return DifferentialOperator([self.parent.base.one], self.parent)
# if self is `Dx`
if self.listofpoly == self.parent.derivative_operator.listofpoly:
sol = []
for i in range(0, n):
sol.append(self.parent.base.zero)
sol.append(self.parent.base.one)
return DifferentialOperator(sol, self.parent)
# the general case
else:
if n % 2 == 1:
powreduce = self**(n - 1)
return powreduce * self
elif n % 2 == 0:
powreduce = self**(n / 2)
return powreduce * powreduce
def __str__(self):
listofpoly = self.listofpoly
print_str = ''
for i, j in enumerate(listofpoly):
if j == self.parent.base.zero:
continue
if i == 0:
print_str += '(' + sstr(j) + ')'
continue
if print_str:
print_str += ' + '
if i == 1:
print_str += '(' + sstr(j) + ')*%s' %(self.parent.gen_symbol)
continue
print_str += '(' + sstr(j) + ')' + '*%s**' %(self.parent.gen_symbol) + sstr(i)
return print_str
__repr__ = __str__
def __eq__(self, other):
if isinstance(other, DifferentialOperator):
if self.listofpoly == other.listofpoly and self.parent == other.parent:
return True
else:
return False
else:
if self.listofpoly[0] == other:
for i in self.listofpoly[1:]:
if i is not self.parent.base.zero:
return False
return True
else:
return False
def is_singular(self, x0):
"""
Checks if the differential equation is singular at x0.
"""
base = self.parent.base
return x0 in roots(base.to_sympy(self.listofpoly[-1]), self.x)
class HolonomicFunction:
r"""
A Holonomic Function is a solution to a linear homogeneous ordinary
differential equation with polynomial coefficients. This differential
equation can also be represented by an annihilator i.e. a Differential
Operator ``L`` such that :math:`L.f = 0`. For uniqueness of these functions,
initial conditions can also be provided along with the annihilator.
Explanation
===========
Holonomic functions have closure properties and thus forms a ring.
Given two Holonomic Functions f and g, their sum, product,
integral and derivative is also a Holonomic Function.
For ordinary points initial condition should be a vector of values of
the derivatives i.e. :math:`[y(x_0), y'(x_0), y''(x_0) ... ]`.
For regular singular points initial conditions can also be provided in this
format:
:math:`{s0: [C_0, C_1, ...], s1: [C^1_0, C^1_1, ...], ...}`
where s0, s1, ... are the roots of indicial equation and vectors
:math:`[C_0, C_1, ...], [C^0_0, C^0_1, ...], ...` are the corresponding initial
terms of the associated power series. See Examples below.
Examples
========
>>> from sympy.holonomic.holonomic import HolonomicFunction, DifferentialOperators
>>> from sympy.polys.domains import QQ
>>> from sympy import symbols, S
>>> x = symbols('x')
>>> R, Dx = DifferentialOperators(QQ.old_poly_ring(x),'Dx')
>>> p = HolonomicFunction(Dx - 1, x, 0, [1]) # e^x
>>> q = HolonomicFunction(Dx**2 + 1, x, 0, [0, 1]) # sin(x)
>>> p + q # annihilator of e^x + sin(x)
HolonomicFunction((-1) + (1)*Dx + (-1)*Dx**2 + (1)*Dx**3, x, 0, [1, 2, 1])
>>> p * q # annihilator of e^x * sin(x)
HolonomicFunction((2) + (-2)*Dx + (1)*Dx**2, x, 0, [0, 1])
An example of initial conditions for regular singular points,
the indicial equation has only one root `1/2`.
>>> HolonomicFunction(-S(1)/2 + x*Dx, x, 0, {S(1)/2: [1]})
HolonomicFunction((-1/2) + (x)*Dx, x, 0, {1/2: [1]})
>>> HolonomicFunction(-S(1)/2 + x*Dx, x, 0, {S(1)/2: [1]}).to_expr()
sqrt(x)
To plot a Holonomic Function, one can use `.evalf()` for numerical
computation. Here's an example on `sin(x)**2/x` using numpy and matplotlib.
>>> import sympy.holonomic # doctest: +SKIP
>>> from sympy import var, sin # doctest: +SKIP
>>> import matplotlib.pyplot as plt # doctest: +SKIP
>>> import numpy as np # doctest: +SKIP
>>> var("x") # doctest: +SKIP
>>> r = np.linspace(1, 5, 100) # doctest: +SKIP
>>> y = sympy.holonomic.expr_to_holonomic(sin(x)**2/x, x0=1).evalf(r) # doctest: +SKIP
>>> plt.plot(r, y, label="holonomic function") # doctest: +SKIP
>>> plt.show() # doctest: +SKIP
"""
_op_priority = 20
def __init__(self, annihilator, x, x0=0, y0=None):
"""
Parameters
==========
annihilator:
Annihilator of the Holonomic Function, represented by a
`DifferentialOperator` object.
x:
Variable of the function.
x0:
The point at which initial conditions are stored.
Generally an integer.
y0:
The initial condition. The proper format for the initial condition
is described in class docstring. To make the function unique,
length of the vector `y0` should be equal to or greater than the
order of differential equation.
"""
# initial condition
self.y0 = y0
# the point for initial conditions, default is zero.
self.x0 = x0
# differential operator L such that L.f = 0
self.annihilator = annihilator
self.x = x
def __str__(self):
if self._have_init_cond():
str_sol = 'HolonomicFunction(%s, %s, %s, %s)' % (str(self.annihilator),\
sstr(self.x), sstr(self.x0), sstr(self.y0))
else:
str_sol = 'HolonomicFunction(%s, %s)' % (str(self.annihilator),\
sstr(self.x))
return str_sol
__repr__ = __str__
def unify(self, other):
"""
Unifies the base polynomial ring of a given two Holonomic
Functions.
"""
R1 = self.annihilator.parent.base
R2 = other.annihilator.parent.base
dom1 = R1.dom
dom2 = R2.dom
if R1 == R2:
return (self, other)
R = (dom1.unify(dom2)).old_poly_ring(self.x)
newparent, _ = DifferentialOperators(R, str(self.annihilator.parent.gen_symbol))
sol1 = [R1.to_sympy(i) for i in self.annihilator.listofpoly]
sol2 = [R2.to_sympy(i) for i in other.annihilator.listofpoly]
sol1 = DifferentialOperator(sol1, newparent)
sol2 = DifferentialOperator(sol2, newparent)
sol1 = HolonomicFunction(sol1, self.x, self.x0, self.y0)
sol2 = HolonomicFunction(sol2, other.x, other.x0, other.y0)
return (sol1, sol2)
def is_singularics(self):
"""
Returns True if the function have singular initial condition
in the dictionary format.
Returns False if the function have ordinary initial condition
in the list format.
Returns None for all other cases.
"""
if isinstance(self.y0, dict):
return True
elif isinstance(self.y0, list):
return False
def _have_init_cond(self):
"""
Checks if the function have initial condition.
"""
return bool(self.y0)
def _singularics_to_ord(self):
"""
Converts a singular initial condition to ordinary if possible.
"""
a = list(self.y0)[0]
b = self.y0[a]
if len(self.y0) == 1 and a == int(a) and a > 0:
y0 = []
a = int(a)
for i in range(a):
y0.append(S.Zero)
y0 += [j * factorial(a + i) for i, j in enumerate(b)]
return HolonomicFunction(self.annihilator, self.x, self.x0, y0)
def __add__(self, other):
# if the ground domains are different
if self.annihilator.parent.base != other.annihilator.parent.base:
a, b = self.unify(other)
return a + b
deg1 = self.annihilator.order
deg2 = other.annihilator.order
dim = max(deg1, deg2)
R = self.annihilator.parent.base
K = R.get_field()
rowsself = [self.annihilator]
rowsother = [other.annihilator]
gen = self.annihilator.parent.derivative_operator
# constructing annihilators up to order dim
for i in range(dim - deg1):
diff1 = (gen * rowsself[-1])
rowsself.append(diff1)
for i in range(dim - deg2):
diff2 = (gen * rowsother[-1])
rowsother.append(diff2)
row = rowsself + rowsother
# constructing the matrix of the ansatz
r = []
for expr in row:
p = []
for i in range(dim + 1):
if i >= len(expr.listofpoly):
p.append(K.zero)
else:
p.append(K.new(expr.listofpoly[i].rep))
r.append(p)
# solving the linear system using gauss jordan solver
r = DomainMatrix(r, (len(row), dim+1), K).transpose()
homosys = DomainMatrix.zeros((dim+1, 1), K)
sol = _find_nonzero_solution(r, homosys)
# if a solution is not obtained then increasing the order by 1 in each
# iteration
while sol.is_zero_matrix:
dim += 1
diff1 = (gen * rowsself[-1])
rowsself.append(diff1)
diff2 = (gen * rowsother[-1])
rowsother.append(diff2)
row = rowsself + rowsother
r = []
for expr in row:
p = []
for i in range(dim + 1):
if i >= len(expr.listofpoly):
p.append(K.zero)
else:
p.append(K.new(expr.listofpoly[i].rep))
r.append(p)
# solving the linear system using gauss jordan solver
r = DomainMatrix(r, (len(row), dim+1), K).transpose()
homosys = DomainMatrix.zeros((dim+1, 1), K)
sol = _find_nonzero_solution(r, homosys)
# taking only the coefficients needed to multiply with `self`
# can be also be done the other way by taking R.H.S and multiplying with
# `other`
sol = sol.flat()[:dim + 1 - deg1]
sol1 = _normalize(sol, self.annihilator.parent)
# annihilator of the solution
sol = sol1 * (self.annihilator)
sol = _normalize(sol.listofpoly, self.annihilator.parent, negative=False)
if not (self._have_init_cond() and other._have_init_cond()):
return HolonomicFunction(sol, self.x)
# both the functions have ordinary initial conditions
if self.is_singularics() == False and other.is_singularics() == False:
# directly add the corresponding value
if self.x0 == other.x0:
# try to extended the initial conditions
# using the annihilator
y1 = _extend_y0(self, sol.order)
y2 = _extend_y0(other, sol.order)
y0 = [a + b for a, b in zip(y1, y2)]
return HolonomicFunction(sol, self.x, self.x0, y0)
else:
# change the intiial conditions to a same point
selfat0 = self.annihilator.is_singular(0)
otherat0 = other.annihilator.is_singular(0)
if self.x0 == 0 and not selfat0 and not otherat0:
return self + other.change_ics(0)
elif other.x0 == 0 and not selfat0 and not otherat0:
return self.change_ics(0) + other
else:
selfatx0 = self.annihilator.is_singular(self.x0)
otheratx0 = other.annihilator.is_singular(self.x0)
if not selfatx0 and not otheratx0:
return self + other.change_ics(self.x0)
else:
return self.change_ics(other.x0) + other
if self.x0 != other.x0:
return HolonomicFunction(sol, self.x)
# if the functions have singular_ics
y1 = None
y2 = None
if self.is_singularics() == False and other.is_singularics() == True:
# convert the ordinary initial condition to singular.
_y0 = [j / factorial(i) for i, j in enumerate(self.y0)]
y1 = {S.Zero: _y0}
y2 = other.y0
elif self.is_singularics() == True and other.is_singularics() == False:
_y0 = [j / factorial(i) for i, j in enumerate(other.y0)]
y1 = self.y0
y2 = {S.Zero: _y0}
elif self.is_singularics() == True and other.is_singularics() == True:
y1 = self.y0
y2 = other.y0
# computing singular initial condition for the result
# taking union of the series terms of both functions
y0 = {}
for i in y1:
# add corresponding initial terms if the power
# on `x` is same
if i in y2:
y0[i] = [a + b for a, b in zip(y1[i], y2[i])]
else:
y0[i] = y1[i]
for i in y2:
if not i in y1:
y0[i] = y2[i]
return HolonomicFunction(sol, self.x, self.x0, y0)
def integrate(self, limits, initcond=False):
"""
Integrates the given holonomic function.
Examples
========
>>> from sympy.holonomic.holonomic import HolonomicFunction, DifferentialOperators
>>> from sympy.polys.domains import QQ
>>> from sympy import symbols
>>> x = symbols('x')
>>> R, Dx = DifferentialOperators(QQ.old_poly_ring(x),'Dx')
>>> HolonomicFunction(Dx - 1, x, 0, [1]).integrate((x, 0, x)) # e^x - 1
HolonomicFunction((-1)*Dx + (1)*Dx**2, x, 0, [0, 1])
>>> HolonomicFunction(Dx**2 + 1, x, 0, [1, 0]).integrate((x, 0, x))
HolonomicFunction((1)*Dx + (1)*Dx**3, x, 0, [0, 1, 0])
"""
# to get the annihilator, just multiply by Dx from right
D = self.annihilator.parent.derivative_operator
# if the function have initial conditions of the series format
if self.is_singularics() == True:
r = self._singularics_to_ord()
if r:
return r.integrate(limits, initcond=initcond)
# computing singular initial condition for the function
# produced after integration.
y0 = {}
for i in self.y0:
c = self.y0[i]
c2 = []
for j in range(len(c)):
if c[j] == 0:
c2.append(S.Zero)
# if power on `x` is -1, the integration becomes log(x)
# TODO: Implement this case
elif i + j + 1 == 0:
raise NotImplementedError("logarithmic terms in the series are not supported")
else:
c2.append(c[j] / S(i + j + 1))
y0[i + 1] = c2
if hasattr(limits, "__iter__"):
raise NotImplementedError("Definite integration for singular initial conditions")
return HolonomicFunction(self.annihilator * D, self.x, self.x0, y0)
# if no initial conditions are available for the function
if not self._have_init_cond():
if initcond:
return HolonomicFunction(self.annihilator * D, self.x, self.x0, [S.Zero])
return HolonomicFunction(self.annihilator * D, self.x)
# definite integral
# initial conditions for the answer will be stored at point `a`,
# where `a` is the lower limit of the integrand
if hasattr(limits, "__iter__"):
if len(limits) == 3 and limits[0] == self.x:
x0 = self.x0
a = limits[1]
b = limits[2]
definite = True
else:
definite = False
y0 = [S.Zero]
y0 += self.y0
indefinite_integral = HolonomicFunction(self.annihilator * D, self.x, self.x0, y0)
if not definite:
return indefinite_integral
# use evalf to get the values at `a`
if x0 != a:
try:
indefinite_expr = indefinite_integral.to_expr()
except (NotHyperSeriesError, NotPowerSeriesError):
indefinite_expr = None
if indefinite_expr:
lower = indefinite_expr.subs(self.x, a)
if isinstance(lower, NaN):
lower = indefinite_expr.limit(self.x, a)
else:
lower = indefinite_integral.evalf(a)
if b == self.x:
y0[0] = y0[0] - lower
return HolonomicFunction(self.annihilator * D, self.x, x0, y0)
elif S(b).is_Number:
if indefinite_expr:
upper = indefinite_expr.subs(self.x, b)
if isinstance(upper, NaN):
upper = indefinite_expr.limit(self.x, b)
else:
upper = indefinite_integral.evalf(b)
return upper - lower
# if the upper limit is `x`, the answer will be a function
if b == self.x:
return HolonomicFunction(self.annihilator * D, self.x, a, y0)
# if the upper limits is a Number, a numerical value will be returned
elif S(b).is_Number:
try:
s = HolonomicFunction(self.annihilator * D, self.x, a,\
y0).to_expr()
indefinite = s.subs(self.x, b)
if not isinstance(indefinite, NaN):
return indefinite
else:
return s.limit(self.x, b)
except (NotHyperSeriesError, NotPowerSeriesError):
return HolonomicFunction(self.annihilator * D, self.x, a, y0).evalf(b)
return HolonomicFunction(self.annihilator * D, self.x)
def diff(self, *args, **kwargs):
r"""
Differentiation of the given Holonomic function.
Examples
========
>>> from sympy.holonomic.holonomic import HolonomicFunction, DifferentialOperators
>>> from sympy.polys.domains import ZZ
>>> from sympy import symbols
>>> x = symbols('x')
>>> R, Dx = DifferentialOperators(ZZ.old_poly_ring(x),'Dx')
>>> HolonomicFunction(Dx**2 + 1, x, 0, [0, 1]).diff().to_expr()
cos(x)
>>> HolonomicFunction(Dx - 2, x, 0, [1]).diff().to_expr()
2*exp(2*x)
See Also
========
.integrate()
"""
kwargs.setdefault('evaluate', True)
if args:
if args[0] != self.x:
return S.Zero
elif len(args) == 2:
sol = self
for i in range(args[1]):
sol = sol.diff(args[0])
return sol
ann = self.annihilator
# if the function is constant.
if ann.listofpoly[0] == ann.parent.base.zero and ann.order == 1:
return S.Zero
# if the coefficient of y in the differential equation is zero.
# a shifting is done to compute the answer in this case.
elif ann.listofpoly[0] == ann.parent.base.zero:
sol = DifferentialOperator(ann.listofpoly[1:], ann.parent)
if self._have_init_cond():
# if ordinary initial condition
if self.is_singularics() == False:
return HolonomicFunction(sol, self.x, self.x0, self.y0[1:])
# TODO: support for singular initial condition
return HolonomicFunction(sol, self.x)
else:
return HolonomicFunction(sol, self.x)
# the general algorithm
R = ann.parent.base
K = R.get_field()
seq_dmf = [K.new(i.rep) for i in ann.listofpoly]
# -y = a1*y'/a0 + a2*y''/a0 ... + an*y^n/a0
rhs = [i / seq_dmf[0] for i in seq_dmf[1:]]
rhs.insert(0, K.zero)
# differentiate both lhs and rhs
sol = _derivate_diff_eq(rhs)
# add the term y' in lhs to rhs
sol = _add_lists(sol, [K.zero, K.one])
sol = _normalize(sol[1:], self.annihilator.parent, negative=False)
if not self._have_init_cond() or self.is_singularics() == True:
return HolonomicFunction(sol, self.x)
y0 = _extend_y0(self, sol.order + 1)[1:]
return HolonomicFunction(sol, self.x, self.x0, y0)
def __eq__(self, other):
if self.annihilator == other.annihilator:
if self.x == other.x:
if self._have_init_cond() and other._have_init_cond():
if self.x0 == other.x0 and self.y0 == other.y0:
return True
else:
return False
else:
return True
else:
return False
else:
return False
def __mul__(self, other):
ann_self = self.annihilator
if not isinstance(other, HolonomicFunction):
other = sympify(other)
if other.has(self.x):
raise NotImplementedError(" Can't multiply a HolonomicFunction and expressions/functions.")
if not self._have_init_cond():
return self
else:
y0 = _extend_y0(self, ann_self.order)
y1 = []
for j in y0:
y1.append((Poly.new(j, self.x) * other).rep)
return HolonomicFunction(ann_self, self.x, self.x0, y1)
if self.annihilator.parent.base != other.annihilator.parent.base:
a, b = self.unify(other)
return a * b
ann_other = other.annihilator
list_self = []
list_other = []
a = ann_self.order
b = ann_other.order
R = ann_self.parent.base
K = R.get_field()
for j in ann_self.listofpoly:
list_self.append(K.new(j.rep))
for j in ann_other.listofpoly:
list_other.append(K.new(j.rep))
# will be used to reduce the degree
self_red = [-list_self[i] / list_self[a] for i in range(a)]
other_red = [-list_other[i] / list_other[b] for i in range(b)]
# coeff_mull[i][j] is the coefficient of Dx^i(f).Dx^j(g)
coeff_mul = [[K.zero for i in range(b + 1)] for j in range(a + 1)]
coeff_mul[0][0] = K.one
# making the ansatz
lin_sys_elements = [[coeff_mul[i][j] for i in range(a) for j in range(b)]]
lin_sys = DomainMatrix(lin_sys_elements, (1, a*b), K).transpose()
homo_sys = DomainMatrix.zeros((a*b, 1), K)
sol = _find_nonzero_solution(lin_sys, homo_sys)
# until a non trivial solution is found
while sol.is_zero_matrix:
# updating the coefficients Dx^i(f).Dx^j(g) for next degree
for i in range(a - 1, -1, -1):
for j in range(b - 1, -1, -1):
coeff_mul[i][j + 1] += coeff_mul[i][j]
coeff_mul[i + 1][j] += coeff_mul[i][j]
if isinstance(coeff_mul[i][j], K.dtype):
coeff_mul[i][j] = DMFdiff(coeff_mul[i][j])
else:
coeff_mul[i][j] = coeff_mul[i][j].diff(self.x)
# reduce the terms to lower power using annihilators of f, g
for i in range(a + 1):
if not coeff_mul[i][b].is_zero:
for j in range(b):
coeff_mul[i][j] += other_red[j] * \
coeff_mul[i][b]
coeff_mul[i][b] = K.zero
# not d2 + 1, as that is already covered in previous loop
for j in range(b):
if not coeff_mul[a][j] == 0:
for i in range(a):
coeff_mul[i][j] += self_red[i] * \
coeff_mul[a][j]
coeff_mul[a][j] = K.zero
lin_sys_elements.append([coeff_mul[i][j] for i in range(a) for j in range(b)])
lin_sys = DomainMatrix(lin_sys_elements, (len(lin_sys_elements), a*b), K).transpose()
sol = _find_nonzero_solution(lin_sys, homo_sys)
sol_ann = _normalize(sol.flat(), self.annihilator.parent, negative=False)
if not (self._have_init_cond() and other._have_init_cond()):
return HolonomicFunction(sol_ann, self.x)
if self.is_singularics() == False and other.is_singularics() == False:
# if both the conditions are at same point
if self.x0 == other.x0:
# try to find more initial conditions
y0_self = _extend_y0(self, sol_ann.order)
y0_other = _extend_y0(other, sol_ann.order)
# h(x0) = f(x0) * g(x0)
y0 = [y0_self[0] * y0_other[0]]
# coefficient of Dx^j(f)*Dx^i(g) in Dx^i(fg)
for i in range(1, min(len(y0_self), len(y0_other))):
coeff = [[0 for i in range(i + 1)] for j in range(i + 1)]
for j in range(i + 1):
for k in range(i + 1):
if j + k == i:
coeff[j][k] = binomial(i, j)
sol = 0
for j in range(i + 1):
for k in range(i + 1):
sol += coeff[j][k]* y0_self[j] * y0_other[k]
y0.append(sol)
return HolonomicFunction(sol_ann, self.x, self.x0, y0)
# if the points are different, consider one
else:
selfat0 = self.annihilator.is_singular(0)
otherat0 = other.annihilator.is_singular(0)
if self.x0 == 0 and not selfat0 and not otherat0:
return self * other.change_ics(0)
elif other.x0 == 0 and not selfat0 and not otherat0:
return self.change_ics(0) * other
else:
selfatx0 = self.annihilator.is_singular(self.x0)
otheratx0 = other.annihilator.is_singular(self.x0)
if not selfatx0 and not otheratx0:
return self * other.change_ics(self.x0)
else:
return self.change_ics(other.x0) * other
if self.x0 != other.x0:
return HolonomicFunction(sol_ann, self.x)
# if the functions have singular_ics
y1 = None
y2 = None
if self.is_singularics() == False and other.is_singularics() == True:
_y0 = [j / factorial(i) for i, j in enumerate(self.y0)]
y1 = {S.Zero: _y0}
y2 = other.y0
elif self.is_singularics() == True and other.is_singularics() == False:
_y0 = [j / factorial(i) for i, j in enumerate(other.y0)]
y1 = self.y0
y2 = {S.Zero: _y0}
elif self.is_singularics() == True and other.is_singularics() == True:
y1 = self.y0
y2 = other.y0
y0 = {}
# multiply every possible pair of the series terms
for i in y1:
for j in y2:
k = min(len(y1[i]), len(y2[j]))
c = []
for a in range(k):
s = S.Zero
for b in range(a + 1):
s += y1[i][b] * y2[j][a - b]
c.append(s)
if not i + j in y0:
y0[i + j] = c
else:
y0[i + j] = [a + b for a, b in zip(c, y0[i + j])]
return HolonomicFunction(sol_ann, self.x, self.x0, y0)
__rmul__ = __mul__
def __sub__(self, other):
return self + other * -1
def __rsub__(self, other):
return self * -1 + other
def __neg__(self):
return -1 * self
def __truediv__(self, other):
return self * (S.One / other)
def __pow__(self, n):
if self.annihilator.order <= 1:
ann = self.annihilator
parent = ann.parent
if self.y0 is None:
y0 = None
else:
y0 = [list(self.y0)[0] ** n]
p0 = ann.listofpoly[0]
p1 = ann.listofpoly[1]
p0 = (Poly.new(p0, self.x) * n).rep
sol = [parent.base.to_sympy(i) for i in [p0, p1]]
dd = DifferentialOperator(sol, parent)
return HolonomicFunction(dd, self.x, self.x0, y0)
if n < 0:
raise NotHolonomicError("Negative Power on a Holonomic Function")
if n == 0:
Dx = self.annihilator.parent.derivative_operator
return HolonomicFunction(Dx, self.x, S.Zero, [S.One])
if n == 1:
return self
else:
if n % 2 == 1:
powreduce = self**(n - 1)
return powreduce * self
elif n % 2 == 0:
powreduce = self**(n / 2)
return powreduce * powreduce
def degree(self):
"""
Returns the highest power of `x` in the annihilator.
"""
sol = [i.degree() for i in self.annihilator.listofpoly]
return max(sol)
def composition(self, expr, *args, **kwargs):
"""
Returns function after composition of a holonomic
function with an algebraic function. The method can't compute
initial conditions for the result by itself, so they can be also be
provided.
Examples
========
>>> from sympy.holonomic.holonomic import HolonomicFunction, DifferentialOperators
>>> from sympy.polys.domains import QQ
>>> from sympy import symbols
>>> x = symbols('x')
>>> R, Dx = DifferentialOperators(QQ.old_poly_ring(x),'Dx')
>>> HolonomicFunction(Dx - 1, x).composition(x**2, 0, [1]) # e^(x**2)
HolonomicFunction((-2*x) + (1)*Dx, x, 0, [1])
>>> HolonomicFunction(Dx**2 + 1, x).composition(x**2 - 1, 1, [1, 0])
HolonomicFunction((4*x**3) + (-1)*Dx + (x)*Dx**2, x, 1, [1, 0])
See Also
========
from_hyper()
"""
R = self.annihilator.parent
a = self.annihilator.order
diff = expr.diff(self.x)
listofpoly = self.annihilator.listofpoly
for i, j in enumerate(listofpoly):
if isinstance(j, self.annihilator.parent.base.dtype):
listofpoly[i] = self.annihilator.parent.base.to_sympy(j)
r = listofpoly[a].subs({self.x:expr})
subs = [-listofpoly[i].subs({self.x:expr}) / r for i in range (a)]
coeffs = [S.Zero for i in range(a)] # coeffs[i] == coeff of (D^i f)(a) in D^k (f(a))
coeffs[0] = S.One
system = [coeffs]
homogeneous = Matrix([[S.Zero for i in range(a)]]).transpose()
while True:
coeffs_next = [p.diff(self.x) for p in coeffs]
for i in range(a - 1):
coeffs_next[i + 1] += (coeffs[i] * diff)
for i in range(a):
coeffs_next[i] += (coeffs[-1] * subs[i] * diff)
coeffs = coeffs_next
# check for linear relations
system.append(coeffs)
sol, taus = (Matrix(system).transpose()
).gauss_jordan_solve(homogeneous)
if sol.is_zero_matrix is not True:
break
tau = list(taus)[0]
sol = sol.subs(tau, 1)
sol = _normalize(sol[0:], R, negative=False)
# if initial conditions are given for the resulting function
if args:
return HolonomicFunction(sol, self.x, args[0], args[1])
return HolonomicFunction(sol, self.x)
def to_sequence(self, lb=True):
r"""
Finds recurrence relation for the coefficients in the series expansion
of the function about :math:`x_0`, where :math:`x_0` is the point at
which the initial condition is stored.
Explanation
===========
If the point :math:`x_0` is ordinary, solution of the form :math:`[(R, n_0)]`
is returned. Where :math:`R` is the recurrence relation and :math:`n_0` is the
smallest ``n`` for which the recurrence holds true.
If the point :math:`x_0` is regular singular, a list of solutions in
the format :math:`(R, p, n_0)` is returned, i.e. `[(R, p, n_0), ... ]`.
Each tuple in this vector represents a recurrence relation :math:`R`
associated with a root of the indicial equation ``p``. Conditions of
a different format can also be provided in this case, see the
docstring of HolonomicFunction class.
If it's not possible to numerically compute a initial condition,
it is returned as a symbol :math:`C_j`, denoting the coefficient of
:math:`(x - x_0)^j` in the power series about :math:`x_0`.
Examples
========
>>> from sympy.holonomic.holonomic import HolonomicFunction, DifferentialOperators
>>> from sympy.polys.domains import QQ
>>> from sympy import symbols, S
>>> x = symbols('x')
>>> R, Dx = DifferentialOperators(QQ.old_poly_ring(x),'Dx')
>>> HolonomicFunction(Dx - 1, x, 0, [1]).to_sequence()
[(HolonomicSequence((-1) + (n + 1)Sn, n), u(0) = 1, 0)]
>>> HolonomicFunction((1 + x)*Dx**2 + Dx, x, 0, [0, 1]).to_sequence()
[(HolonomicSequence((n**2) + (n**2 + n)Sn, n), u(0) = 0, u(1) = 1, u(2) = -1/2, 2)]
>>> HolonomicFunction(-S(1)/2 + x*Dx, x, 0, {S(1)/2: [1]}).to_sequence()
[(HolonomicSequence((n), n), u(0) = 1, 1/2, 1)]
See Also
========
HolonomicFunction.series()
References
==========
.. [1] https://hal.inria.fr/inria-00070025/document
.. [2] http://www.risc.jku.at/publications/download/risc_2244/DIPLFORM.pdf
"""
if self.x0 != 0:
return self.shift_x(self.x0).to_sequence()
# check whether a power series exists if the point is singular
if self.annihilator.is_singular(self.x0):
return self._frobenius(lb=lb)
dict1 = {}
n = Symbol('n', integer=True)
dom = self.annihilator.parent.base.dom
R, _ = RecurrenceOperators(dom.old_poly_ring(n), 'Sn')
# substituting each term of the form `x^k Dx^j` in the
# annihilator, according to the formula below:
# x^k Dx^j = Sum(rf(n + 1 - k, j) * a(n + j - k) * x^n, (n, k, oo))
# for explanation see [2].
for i, j in enumerate(self.annihilator.listofpoly):
listofdmp = j.all_coeffs()
degree = len(listofdmp) - 1
for k in range(degree + 1):
coeff = listofdmp[degree - k]
if coeff == 0:
continue
if (i - k, k) in dict1:
dict1[(i - k, k)] += (dom.to_sympy(coeff) * rf(n - k + 1, i))
else:
dict1[(i - k, k)] = (dom.to_sympy(coeff) * rf(n - k + 1, i))
sol = []
keylist = [i[0] for i in dict1]
lower = min(keylist)
upper = max(keylist)
degree = self.degree()
# the recurrence relation holds for all values of
# n greater than smallest_n, i.e. n >= smallest_n
smallest_n = lower + degree
dummys = {}
eqs = []
unknowns = []
# an appropriate shift of the recurrence
for j in range(lower, upper + 1):
if j in keylist:
temp = S.Zero
for k in dict1.keys():
if k[0] == j:
temp += dict1[k].subs(n, n - lower)
sol.append(temp)
else:
sol.append(S.Zero)
# the recurrence relation
sol = RecurrenceOperator(sol, R)
# computing the initial conditions for recurrence
order = sol.order
all_roots = roots(R.base.to_sympy(sol.listofpoly[-1]), n, filter='Z')
all_roots = all_roots.keys()
if all_roots:
max_root = max(all_roots) + 1
smallest_n = max(max_root, smallest_n)
order += smallest_n
y0 = _extend_y0(self, order)
u0 = []
# u(n) = y^n(0)/factorial(n)
for i, j in enumerate(y0):
u0.append(j / factorial(i))
# if sufficient conditions can't be computed then
# try to use the series method i.e.
# equate the coefficients of x^k in the equation formed by
# substituting the series in differential equation, to zero.
if len(u0) < order:
for i in range(degree):
eq = S.Zero
for j in dict1:
if i + j[0] < 0:
dummys[i + j[0]] = S.Zero
elif i + j[0] < len(u0):
dummys[i + j[0]] = u0[i + j[0]]
elif not i + j[0] in dummys:
dummys[i + j[0]] = Symbol('C_%s' %(i + j[0]))
unknowns.append(dummys[i + j[0]])
if j[1] <= i:
eq += dict1[j].subs(n, i) * dummys[i + j[0]]
eqs.append(eq)
# solve the system of equations formed
soleqs = solve(eqs, *unknowns)
if isinstance(soleqs, dict):
for i in range(len(u0), order):
if i not in dummys:
dummys[i] = Symbol('C_%s' %i)
if dummys[i] in soleqs:
u0.append(soleqs[dummys[i]])
else:
u0.append(dummys[i])
if lb:
return [(HolonomicSequence(sol, u0), smallest_n)]
return [HolonomicSequence(sol, u0)]
for i in range(len(u0), order):
if i not in dummys:
dummys[i] = Symbol('C_%s' %i)
s = False
for j in soleqs:
if dummys[i] in j:
u0.append(j[dummys[i]])
s = True
if not s:
u0.append(dummys[i])
if lb:
return [(HolonomicSequence(sol, u0), smallest_n)]
return [HolonomicSequence(sol, u0)]
def _frobenius(self, lb=True):
# compute the roots of indicial equation
indicialroots = self._indicial()
reals = []
compl = []
for i in ordered(indicialroots.keys()):
if i.is_real:
reals.extend([i] * indicialroots[i])
else:
a, b = i.as_real_imag()
compl.extend([(i, a, b)] * indicialroots[i])
# sort the roots for a fixed ordering of solution
compl.sort(key=lambda x : x[1])
compl.sort(key=lambda x : x[2])
reals.sort()
# grouping the roots, roots differ by an integer are put in the same group.
grp = []
for i in reals:
intdiff = False
if len(grp) == 0:
grp.append([i])
continue
for j in grp:
if int(j[0] - i) == j[0] - i:
j.append(i)
intdiff = True
break
if not intdiff:
grp.append([i])
# True if none of the roots differ by an integer i.e.
# each element in group have only one member
independent = True if all(len(i) == 1 for i in grp) else False
allpos = all(i >= 0 for i in reals)
allint = all(int(i) == i for i in reals)
# if initial conditions are provided
# then use them.
if self.is_singularics() == True:
rootstoconsider = []
for i in ordered(self.y0.keys()):
for j in ordered(indicialroots.keys()):
if j == i:
rootstoconsider.append(i)
elif allpos and allint:
rootstoconsider = [min(reals)]
elif independent:
rootstoconsider = [i[0] for i in grp] + [j[0] for j in compl]
elif not allint:
rootstoconsider = []
for i in reals:
if not int(i) == i:
rootstoconsider.append(i)
elif not allpos:
if not self._have_init_cond() or S(self.y0[0]).is_finite == False:
rootstoconsider = [min(reals)]
else:
posroots = []
for i in reals:
if i >= 0:
posroots.append(i)
rootstoconsider = [min(posroots)]
n = Symbol('n', integer=True)
dom = self.annihilator.parent.base.dom
R, _ = RecurrenceOperators(dom.old_poly_ring(n), 'Sn')
finalsol = []
char = ord('C')
for p in rootstoconsider:
dict1 = {}
for i, j in enumerate(self.annihilator.listofpoly):
listofdmp = j.all_coeffs()
degree = len(listofdmp) - 1
for k in range(degree + 1):
coeff = listofdmp[degree - k]
if coeff == 0:
continue
if (i - k, k - i) in dict1:
dict1[(i - k, k - i)] += (dom.to_sympy(coeff) * rf(n - k + 1 + p, i))
else:
dict1[(i - k, k - i)] = (dom.to_sympy(coeff) * rf(n - k + 1 + p, i))
sol = []
keylist = [i[0] for i in dict1]
lower = min(keylist)
upper = max(keylist)
degree = max([i[1] for i in dict1])
degree2 = min([i[1] for i in dict1])
smallest_n = lower + degree
dummys = {}
eqs = []
unknowns = []
for j in range(lower, upper + 1):
if j in keylist:
temp = S.Zero
for k in dict1.keys():
if k[0] == j:
temp += dict1[k].subs(n, n - lower)
sol.append(temp)
else:
sol.append(S.Zero)
# the recurrence relation
sol = RecurrenceOperator(sol, R)
# computing the initial conditions for recurrence
order = sol.order
all_roots = roots(R.base.to_sympy(sol.listofpoly[-1]), n, filter='Z')
all_roots = all_roots.keys()
if all_roots:
max_root = max(all_roots) + 1
smallest_n = max(max_root, smallest_n)
order += smallest_n
u0 = []
if self.is_singularics() == True:
u0 = self.y0[p]
elif self.is_singularics() == False and p >= 0 and int(p) == p and len(rootstoconsider) == 1:
y0 = _extend_y0(self, order + int(p))
# u(n) = y^n(0)/factorial(n)
if len(y0) > int(p):
for i in range(int(p), len(y0)):
u0.append(y0[i] / factorial(i))
if len(u0) < order:
for i in range(degree2, degree):
eq = S.Zero
for j in dict1:
if i + j[0] < 0:
dummys[i + j[0]] = S.Zero
elif i + j[0] < len(u0):
dummys[i + j[0]] = u0[i + j[0]]
elif not i + j[0] in dummys:
letter = chr(char) + '_%s' %(i + j[0])
dummys[i + j[0]] = Symbol(letter)
unknowns.append(dummys[i + j[0]])
if j[1] <= i:
eq += dict1[j].subs(n, i) * dummys[i + j[0]]
eqs.append(eq)
# solve the system of equations formed
soleqs = solve(eqs, *unknowns)
if isinstance(soleqs, dict):
for i in range(len(u0), order):
if i not in dummys:
letter = chr(char) + '_%s' %i
dummys[i] = Symbol(letter)
if dummys[i] in soleqs:
u0.append(soleqs[dummys[i]])
else:
u0.append(dummys[i])
if lb:
finalsol.append((HolonomicSequence(sol, u0), p, smallest_n))
continue
else:
finalsol.append((HolonomicSequence(sol, u0), p))
continue
for i in range(len(u0), order):
if i not in dummys:
letter = chr(char) + '_%s' %i
dummys[i] = Symbol(letter)
s = False
for j in soleqs:
if dummys[i] in j:
u0.append(j[dummys[i]])
s = True
if not s:
u0.append(dummys[i])
if lb:
finalsol.append((HolonomicSequence(sol, u0), p, smallest_n))
else:
finalsol.append((HolonomicSequence(sol, u0), p))
char += 1
return finalsol
def series(self, n=6, coefficient=False, order=True, _recur=None):
r"""
Finds the power series expansion of given holonomic function about :math:`x_0`.
Explanation
===========
A list of series might be returned if :math:`x_0` is a regular point with
multiple roots of the indicial equation.
Examples
========
>>> from sympy.holonomic.holonomic import HolonomicFunction, DifferentialOperators
>>> from sympy.polys.domains import QQ
>>> from sympy import symbols
>>> x = symbols('x')
>>> R, Dx = DifferentialOperators(QQ.old_poly_ring(x),'Dx')
>>> HolonomicFunction(Dx - 1, x, 0, [1]).series() # e^x
1 + x + x**2/2 + x**3/6 + x**4/24 + x**5/120 + O(x**6)
>>> HolonomicFunction(Dx**2 + 1, x, 0, [0, 1]).series(n=8) # sin(x)
x - x**3/6 + x**5/120 - x**7/5040 + O(x**8)
See Also
========
HolonomicFunction.to_sequence()
"""
if _recur is None:
recurrence = self.to_sequence()
else:
recurrence = _recur
if isinstance(recurrence, tuple) and len(recurrence) == 2:
recurrence = recurrence[0]
constantpower = 0
elif isinstance(recurrence, tuple) and len(recurrence) == 3:
constantpower = recurrence[1]
recurrence = recurrence[0]
elif len(recurrence) == 1 and len(recurrence[0]) == 2:
recurrence = recurrence[0][0]
constantpower = 0
elif len(recurrence) == 1 and len(recurrence[0]) == 3:
constantpower = recurrence[0][1]
recurrence = recurrence[0][0]
else:
sol = []
for i in recurrence:
sol.append(self.series(_recur=i))
return sol
n = n - int(constantpower)
l = len(recurrence.u0) - 1
k = recurrence.recurrence.order
x = self.x
x0 = self.x0
seq_dmp = recurrence.recurrence.listofpoly
R = recurrence.recurrence.parent.base
K = R.get_field()
seq = []
for i, j in enumerate(seq_dmp):
seq.append(K.new(j.rep))
sub = [-seq[i] / seq[k] for i in range(k)]
sol = [i for i in recurrence.u0]
if l + 1 >= n:
pass
else:
# use the initial conditions to find the next term
for i in range(l + 1 - k, n - k):
coeff = S.Zero
for j in range(k):
if i + j >= 0:
coeff += DMFsubs(sub[j], i) * sol[i + j]
sol.append(coeff)
if coefficient:
return sol
ser = S.Zero
for i, j in enumerate(sol):
ser += x**(i + constantpower) * j
if order:
ser += Order(x**(n + int(constantpower)), x)
if x0 != 0:
return ser.subs(x, x - x0)
return ser
def _indicial(self):
"""
Computes roots of the Indicial equation.
"""
if self.x0 != 0:
return self.shift_x(self.x0)._indicial()
list_coeff = self.annihilator.listofpoly
R = self.annihilator.parent.base
x = self.x
s = R.zero
y = R.one
def _pole_degree(poly):
root_all = roots(R.to_sympy(poly), x, filter='Z')
if 0 in root_all.keys():
return root_all[0]
else:
return 0
degree = [j.degree() for j in list_coeff]
degree = max(degree)
inf = 10 * (max(1, degree) + max(1, self.annihilator.order))
deg = lambda q: inf if q.is_zero else _pole_degree(q)
b = deg(list_coeff[0])
for j in range(1, len(list_coeff)):
b = min(b, deg(list_coeff[j]) - j)
for i, j in enumerate(list_coeff):
listofdmp = j.all_coeffs()
degree = len(listofdmp) - 1
if - i - b <= 0 and degree - i - b >= 0:
s = s + listofdmp[degree - i - b] * y
y *= x - i
return roots(R.to_sympy(s), x)
def evalf(self, points, method='RK4', h=0.05, derivatives=False):
r"""
Finds numerical value of a holonomic function using numerical methods.
(RK4 by default). A set of points (real or complex) must be provided
which will be the path for the numerical integration.
Explanation
===========
The path should be given as a list :math:`[x_1, x_2, ... x_n]`. The numerical
values will be computed at each point in this order
:math:`x_1 --> x_2 --> x_3 ... --> x_n`.
Returns values of the function at :math:`x_1, x_2, ... x_n` in a list.
Examples
========
>>> from sympy.holonomic.holonomic import HolonomicFunction, DifferentialOperators
>>> from sympy.polys.domains import QQ
>>> from sympy import symbols
>>> x = symbols('x')
>>> R, Dx = DifferentialOperators(QQ.old_poly_ring(x),'Dx')
A straight line on the real axis from (0 to 1)
>>> r = [0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1]
Runge-Kutta 4th order on e^x from 0.1 to 1.
Exact solution at 1 is 2.71828182845905
>>> HolonomicFunction(Dx - 1, x, 0, [1]).evalf(r)
[1.10517083333333, 1.22140257085069, 1.34985849706254, 1.49182424008069,
1.64872063859684, 1.82211796209193, 2.01375162659678, 2.22553956329232,
2.45960141378007, 2.71827974413517]
Euler's method for the same
>>> HolonomicFunction(Dx - 1, x, 0, [1]).evalf(r, method='Euler')
[1.1, 1.21, 1.331, 1.4641, 1.61051, 1.771561, 1.9487171, 2.14358881,
2.357947691, 2.5937424601]
One can also observe that the value obtained using Runge-Kutta 4th order
is much more accurate than Euler's method.
"""
from sympy.holonomic.numerical import _evalf
lp = False
# if a point `b` is given instead of a mesh
if not hasattr(points, "__iter__"):
lp = True
b = S(points)
if self.x0 == b:
return _evalf(self, [b], method=method, derivatives=derivatives)[-1]
if not b.is_Number:
raise NotImplementedError
a = self.x0
if a > b:
h = -h
n = int((b - a) / h)
points = [a + h]
for i in range(n - 1):
points.append(points[-1] + h)
for i in roots(self.annihilator.parent.base.to_sympy(self.annihilator.listofpoly[-1]), self.x):
if i == self.x0 or i in points:
raise SingularityError(self, i)
if lp:
return _evalf(self, points, method=method, derivatives=derivatives)[-1]
return _evalf(self, points, method=method, derivatives=derivatives)
def change_x(self, z):
"""
Changes only the variable of Holonomic Function, for internal
purposes. For composition use HolonomicFunction.composition()
"""
dom = self.annihilator.parent.base.dom
R = dom.old_poly_ring(z)
parent, _ = DifferentialOperators(R, 'Dx')
sol = []
for j in self.annihilator.listofpoly:
sol.append(R(j.rep))
sol = DifferentialOperator(sol, parent)
return HolonomicFunction(sol, z, self.x0, self.y0)
def shift_x(self, a):
"""
Substitute `x + a` for `x`.
"""
x = self.x
listaftershift = self.annihilator.listofpoly
base = self.annihilator.parent.base
sol = [base.from_sympy(base.to_sympy(i).subs(x, x + a)) for i in listaftershift]
sol = DifferentialOperator(sol, self.annihilator.parent)
x0 = self.x0 - a
if not self._have_init_cond():
return HolonomicFunction(sol, x)
return HolonomicFunction(sol, x, x0, self.y0)
def to_hyper(self, as_list=False, _recur=None):
r"""
Returns a hypergeometric function (or linear combination of them)
representing the given holonomic function.
Explanation
===========
Returns an answer of the form:
`a_1 \cdot x^{b_1} \cdot{hyper()} + a_2 \cdot x^{b_2} \cdot{hyper()} ...`
This is very useful as one can now use ``hyperexpand`` to find the
symbolic expressions/functions.
Examples
========
>>> from sympy.holonomic.holonomic import HolonomicFunction, DifferentialOperators
>>> from sympy.polys.domains import ZZ
>>> from sympy import symbols
>>> x = symbols('x')
>>> R, Dx = DifferentialOperators(ZZ.old_poly_ring(x),'Dx')
>>> # sin(x)
>>> HolonomicFunction(Dx**2 + 1, x, 0, [0, 1]).to_hyper()
x*hyper((), (3/2,), -x**2/4)
>>> # exp(x)
>>> HolonomicFunction(Dx - 1, x, 0, [1]).to_hyper()
hyper((), (), x)
See Also
========
from_hyper, from_meijerg
"""
if _recur is None:
recurrence = self.to_sequence()
else:
recurrence = _recur
if isinstance(recurrence, tuple) and len(recurrence) == 2:
smallest_n = recurrence[1]
recurrence = recurrence[0]
constantpower = 0
elif isinstance(recurrence, tuple) and len(recurrence) == 3:
smallest_n = recurrence[2]
constantpower = recurrence[1]
recurrence = recurrence[0]
elif len(recurrence) == 1 and len(recurrence[0]) == 2:
smallest_n = recurrence[0][1]
recurrence = recurrence[0][0]
constantpower = 0
elif len(recurrence) == 1 and len(recurrence[0]) == 3:
smallest_n = recurrence[0][2]
constantpower = recurrence[0][1]
recurrence = recurrence[0][0]
else:
sol = self.to_hyper(as_list=as_list, _recur=recurrence[0])
for i in recurrence[1:]:
sol += self.to_hyper(as_list=as_list, _recur=i)
return sol
u0 = recurrence.u0
r = recurrence.recurrence
x = self.x
x0 = self.x0
# order of the recurrence relation
m = r.order
# when no recurrence exists, and the power series have finite terms
if m == 0:
nonzeroterms = roots(r.parent.base.to_sympy(r.listofpoly[0]), recurrence.n, filter='R')
sol = S.Zero
for j, i in enumerate(nonzeroterms):
if i < 0 or int(i) != i:
continue
i = int(i)
if i < len(u0):
if isinstance(u0[i], (PolyElement, FracElement)):
u0[i] = u0[i].as_expr()
sol += u0[i] * x**i
else:
sol += Symbol('C_%s' %j) * x**i
if isinstance(sol, (PolyElement, FracElement)):
sol = sol.as_expr() * x**constantpower
else:
sol = sol * x**constantpower
if as_list:
if x0 != 0:
return [(sol.subs(x, x - x0), )]
return [(sol, )]
if x0 != 0:
return sol.subs(x, x - x0)
return sol
if smallest_n + m > len(u0):
raise NotImplementedError("Can't compute sufficient Initial Conditions")
# check if the recurrence represents a hypergeometric series
is_hyper = True
for i in range(1, len(r.listofpoly)-1):
if r.listofpoly[i] != r.parent.base.zero:
is_hyper = False
break
if not is_hyper:
raise NotHyperSeriesError(self, self.x0)
a = r.listofpoly[0]
b = r.listofpoly[-1]
# the constant multiple of argument of hypergeometric function
if isinstance(a.rep[0], (PolyElement, FracElement)):
c = - (S(a.rep[0].as_expr()) * m**(a.degree())) / (S(b.rep[0].as_expr()) * m**(b.degree()))
else:
c = - (S(a.rep[0]) * m**(a.degree())) / (S(b.rep[0]) * m**(b.degree()))
sol = 0
arg1 = roots(r.parent.base.to_sympy(a), recurrence.n)
arg2 = roots(r.parent.base.to_sympy(b), recurrence.n)
# iterate through the initial conditions to find
# the hypergeometric representation of the given
# function.
# The answer will be a linear combination
# of different hypergeometric series which satisfies
# the recurrence.
if as_list:
listofsol = []
for i in range(smallest_n + m):
# if the recurrence relation doesn't hold for `n = i`,
# then a Hypergeometric representation doesn't exist.
# add the algebraic term a * x**i to the solution,
# where a is u0[i]
if i < smallest_n:
if as_list:
listofsol.append(((S(u0[i]) * x**(i+constantpower)).subs(x, x-x0), ))
else:
sol += S(u0[i]) * x**i
continue
# if the coefficient u0[i] is zero, then the
# independent hypergeomtric series starting with
# x**i is not a part of the answer.
if S(u0[i]) == 0:
continue
ap = []
bq = []
# substitute m * n + i for n
for k in ordered(arg1.keys()):
ap.extend([nsimplify((i - k) / m)] * arg1[k])
for k in ordered(arg2.keys()):
bq.extend([nsimplify((i - k) / m)] * arg2[k])
# convention of (k + 1) in the denominator
if 1 in bq:
bq.remove(1)
else:
ap.append(1)
if as_list:
listofsol.append(((S(u0[i])*x**(i+constantpower)).subs(x, x-x0), (hyper(ap, bq, c*x**m)).subs(x, x-x0)))
else:
sol += S(u0[i]) * hyper(ap, bq, c * x**m) * x**i
if as_list:
return listofsol
sol = sol * x**constantpower
if x0 != 0:
return sol.subs(x, x - x0)
return sol
def to_expr(self):
"""
Converts a Holonomic Function back to elementary functions.
Examples
========
>>> from sympy.holonomic.holonomic import HolonomicFunction, DifferentialOperators
>>> from sympy.polys.domains import ZZ
>>> from sympy import symbols, S
>>> x = symbols('x')
>>> R, Dx = DifferentialOperators(ZZ.old_poly_ring(x),'Dx')
>>> HolonomicFunction(x**2*Dx**2 + x*Dx + (x**2 - 1), x, 0, [0, S(1)/2]).to_expr()
besselj(1, x)
>>> HolonomicFunction((1 + x)*Dx**3 + Dx**2, x, 0, [1, 1, 1]).to_expr()
x*log(x + 1) + log(x + 1) + 1
"""
return hyperexpand(self.to_hyper()).simplify()
def change_ics(self, b, lenics=None):
"""
Changes the point `x0` to ``b`` for initial conditions.
Examples
========
>>> from sympy.holonomic import expr_to_holonomic
>>> from sympy import symbols, sin, exp
>>> x = symbols('x')
>>> expr_to_holonomic(sin(x)).change_ics(1)
HolonomicFunction((1) + (1)*Dx**2, x, 1, [sin(1), cos(1)])
>>> expr_to_holonomic(exp(x)).change_ics(2)
HolonomicFunction((-1) + (1)*Dx, x, 2, [exp(2)])
"""
symbolic = True
if lenics is None and len(self.y0) > self.annihilator.order:
lenics = len(self.y0)
dom = self.annihilator.parent.base.domain
try:
sol = expr_to_holonomic(self.to_expr(), x=self.x, x0=b, lenics=lenics, domain=dom)
except (NotPowerSeriesError, NotHyperSeriesError):
symbolic = False
if symbolic and sol.x0 == b:
return sol
y0 = self.evalf(b, derivatives=True)
return HolonomicFunction(self.annihilator, self.x, b, y0)
def to_meijerg(self):
"""
Returns a linear combination of Meijer G-functions.
Examples
========
>>> from sympy.holonomic import expr_to_holonomic
>>> from sympy import sin, cos, hyperexpand, log, symbols
>>> x = symbols('x')
>>> hyperexpand(expr_to_holonomic(cos(x) + sin(x)).to_meijerg())
sin(x) + cos(x)
>>> hyperexpand(expr_to_holonomic(log(x)).to_meijerg()).simplify()
log(x)
See Also
========
to_hyper()
"""
# convert to hypergeometric first
rep = self.to_hyper(as_list=True)
sol = S.Zero
for i in rep:
if len(i) == 1:
sol += i[0]
elif len(i) == 2:
sol += i[0] * _hyper_to_meijerg(i[1])
return sol
def from_hyper(func, x0=0, evalf=False):
r"""
Converts a hypergeometric function to holonomic.
``func`` is the Hypergeometric Function and ``x0`` is the point at
which initial conditions are required.
Examples
========
>>> from sympy.holonomic.holonomic import from_hyper
>>> from sympy import symbols, hyper, S
>>> x = symbols('x')
>>> from_hyper(hyper([], [S(3)/2], x**2/4))
HolonomicFunction((-x) + (2)*Dx + (x)*Dx**2, x, 1, [sinh(1), -sinh(1) + cosh(1)])
"""
a = func.ap
b = func.bq
z = func.args[2]
x = z.atoms(Symbol).pop()
R, Dx = DifferentialOperators(QQ.old_poly_ring(x), 'Dx')
# generalized hypergeometric differential equation
r1 = 1
for i in range(len(a)):
r1 = r1 * (x * Dx + a[i])
r2 = Dx
for i in range(len(b)):
r2 = r2 * (x * Dx + b[i] - 1)
sol = r1 - r2
simp = hyperexpand(func)
if isinstance(simp, Infinity) or isinstance(simp, NegativeInfinity):
return HolonomicFunction(sol, x).composition(z)
def _find_conditions(simp, x, x0, order, evalf=False):
y0 = []
for i in range(order):
if evalf:
val = simp.subs(x, x0).evalf()
else:
val = simp.subs(x, x0)
# return None if it is Infinite or NaN
if val.is_finite is False or isinstance(val, NaN):
return None
y0.append(val)
simp = simp.diff(x)
return y0
# if the function is known symbolically
if not isinstance(simp, hyper):
y0 = _find_conditions(simp, x, x0, sol.order)
while not y0:
# if values don't exist at 0, then try to find initial
# conditions at 1. If it doesn't exist at 1 too then
# try 2 and so on.
x0 += 1
y0 = _find_conditions(simp, x, x0, sol.order)
return HolonomicFunction(sol, x).composition(z, x0, y0)
if isinstance(simp, hyper):
x0 = 1
# use evalf if the function can't be simplified
y0 = _find_conditions(simp, x, x0, sol.order, evalf)
while not y0:
x0 += 1
y0 = _find_conditions(simp, x, x0, sol.order, evalf)
return HolonomicFunction(sol, x).composition(z, x0, y0)
return HolonomicFunction(sol, x).composition(z)
def from_meijerg(func, x0=0, evalf=False, initcond=True, domain=QQ):
"""
Converts a Meijer G-function to Holonomic.
``func`` is the G-Function and ``x0`` is the point at
which initial conditions are required.
Examples
========
>>> from sympy.holonomic.holonomic import from_meijerg
>>> from sympy import symbols, meijerg, S
>>> x = symbols('x')
>>> from_meijerg(meijerg(([], []), ([S(1)/2], [0]), x**2/4))
HolonomicFunction((1) + (1)*Dx**2, x, 0, [0, 1/sqrt(pi)])
"""
a = func.ap
b = func.bq
n = len(func.an)
m = len(func.bm)
p = len(a)
z = func.args[2]
x = z.atoms(Symbol).pop()
R, Dx = DifferentialOperators(domain.old_poly_ring(x), 'Dx')
# compute the differential equation satisfied by the
# Meijer G-function.
mnp = (-1)**(m + n - p)
r1 = x * mnp
for i in range(len(a)):
r1 *= x * Dx + 1 - a[i]
r2 = 1
for i in range(len(b)):
r2 *= x * Dx - b[i]
sol = r1 - r2
if not initcond:
return HolonomicFunction(sol, x).composition(z)
simp = hyperexpand(func)
if isinstance(simp, Infinity) or isinstance(simp, NegativeInfinity):
return HolonomicFunction(sol, x).composition(z)
def _find_conditions(simp, x, x0, order, evalf=False):
y0 = []
for i in range(order):
if evalf:
val = simp.subs(x, x0).evalf()
else:
val = simp.subs(x, x0)
if val.is_finite is False or isinstance(val, NaN):
return None
y0.append(val)
simp = simp.diff(x)
return y0
# computing initial conditions
if not isinstance(simp, meijerg):
y0 = _find_conditions(simp, x, x0, sol.order)
while not y0:
x0 += 1
y0 = _find_conditions(simp, x, x0, sol.order)
return HolonomicFunction(sol, x).composition(z, x0, y0)
if isinstance(simp, meijerg):
x0 = 1
y0 = _find_conditions(simp, x, x0, sol.order, evalf)
while not y0:
x0 += 1
y0 = _find_conditions(simp, x, x0, sol.order, evalf)
return HolonomicFunction(sol, x).composition(z, x0, y0)
return HolonomicFunction(sol, x).composition(z)
x_1 = Dummy('x_1')
_lookup_table = None
domain_for_table = None
from sympy.integrals.meijerint import _mytype
def expr_to_holonomic(func, x=None, x0=0, y0=None, lenics=None, domain=None, initcond=True):
"""
Converts a function or an expression to a holonomic function.
Parameters
==========
func:
The expression to be converted.
x:
variable for the function.
x0:
point at which initial condition must be computed.
y0:
One can optionally provide initial condition if the method
isn't able to do it automatically.
lenics:
Number of terms in the initial condition. By default it is
equal to the order of the annihilator.
domain:
Ground domain for the polynomials in ``x`` appearing as coefficients
in the annihilator.
initcond:
Set it false if you don't want the initial conditions to be computed.
Examples
========
>>> from sympy.holonomic.holonomic import expr_to_holonomic
>>> from sympy import sin, exp, symbols
>>> x = symbols('x')
>>> expr_to_holonomic(sin(x))
HolonomicFunction((1) + (1)*Dx**2, x, 0, [0, 1])
>>> expr_to_holonomic(exp(x))
HolonomicFunction((-1) + (1)*Dx, x, 0, [1])
See Also
========
sympy.integrals.meijerint._rewrite1, _convert_poly_rat_alg, _create_table
"""
func = sympify(func)
syms = func.free_symbols
if not x:
if len(syms) == 1:
x= syms.pop()
else:
raise ValueError("Specify the variable for the function")
elif x in syms:
syms.remove(x)
extra_syms = list(syms)
if domain is None:
if func.has(Float):
domain = RR
else:
domain = QQ
if len(extra_syms) != 0:
domain = domain[extra_syms].get_field()
# try to convert if the function is polynomial or rational
solpoly = _convert_poly_rat_alg(func, x, x0=x0, y0=y0, lenics=lenics, domain=domain, initcond=initcond)
if solpoly:
return solpoly
# create the lookup table
global _lookup_table, domain_for_table
if not _lookup_table:
domain_for_table = domain
_lookup_table = {}
_create_table(_lookup_table, domain=domain)
elif domain != domain_for_table:
domain_for_table = domain
_lookup_table = {}
_create_table(_lookup_table, domain=domain)
# use the table directly to convert to Holonomic
if func.is_Function:
f = func.subs(x, x_1)
t = _mytype(f, x_1)
if t in _lookup_table:
l = _lookup_table[t]
sol = l[0][1].change_x(x)
else:
sol = _convert_meijerint(func, x, initcond=False, domain=domain)
if not sol:
raise NotImplementedError
if y0:
sol.y0 = y0
if y0 or not initcond:
sol.x0 = x0
return sol
if not lenics:
lenics = sol.annihilator.order
_y0 = _find_conditions(func, x, x0, lenics)
while not _y0:
x0 += 1
_y0 = _find_conditions(func, x, x0, lenics)
return HolonomicFunction(sol.annihilator, x, x0, _y0)
if y0 or not initcond:
sol = sol.composition(func.args[0])
if y0:
sol.y0 = y0
sol.x0 = x0
return sol
if not lenics:
lenics = sol.annihilator.order
_y0 = _find_conditions(func, x, x0, lenics)
while not _y0:
x0 += 1
_y0 = _find_conditions(func, x, x0, lenics)
return sol.composition(func.args[0], x0, _y0)
# iterate through the expression recursively
args = func.args
f = func.func
from sympy.core import Add, Mul, Pow
sol = expr_to_holonomic(args[0], x=x, initcond=False, domain=domain)
if f is Add:
for i in range(1, len(args)):
sol += expr_to_holonomic(args[i], x=x, initcond=False, domain=domain)
elif f is Mul:
for i in range(1, len(args)):
sol *= expr_to_holonomic(args[i], x=x, initcond=False, domain=domain)
elif f is Pow:
sol = sol**args[1]
sol.x0 = x0
if not sol:
raise NotImplementedError
if y0:
sol.y0 = y0
if y0 or not initcond:
return sol
if sol.y0:
return sol
if not lenics:
lenics = sol.annihilator.order
if sol.annihilator.is_singular(x0):
r = sol._indicial()
l = list(r)
if len(r) == 1 and r[l[0]] == S.One:
r = l[0]
g = func / (x - x0)**r
singular_ics = _find_conditions(g, x, x0, lenics)
singular_ics = [j / factorial(i) for i, j in enumerate(singular_ics)]
y0 = {r:singular_ics}
return HolonomicFunction(sol.annihilator, x, x0, y0)
_y0 = _find_conditions(func, x, x0, lenics)
while not _y0:
x0 += 1
_y0 = _find_conditions(func, x, x0, lenics)
return HolonomicFunction(sol.annihilator, x, x0, _y0)
## Some helper functions ##
def _normalize(list_of, parent, negative=True):
"""
Normalize a given annihilator
"""
num = []
denom = []
base = parent.base
K = base.get_field()
lcm_denom = base.from_sympy(S.One)
list_of_coeff = []
# convert polynomials to the elements of associated
# fraction field
for i, j in enumerate(list_of):
if isinstance(j, base.dtype):
list_of_coeff.append(K.new(j.rep))
elif not isinstance(j, K.dtype):
list_of_coeff.append(K.from_sympy(sympify(j)))
else:
list_of_coeff.append(j)
# corresponding numerators of the sequence of polynomials
num.append(list_of_coeff[i].numer())
# corresponding denominators
denom.append(list_of_coeff[i].denom())
# lcm of denominators in the coefficients
for i in denom:
lcm_denom = i.lcm(lcm_denom)
if negative:
lcm_denom = -lcm_denom
lcm_denom = K.new(lcm_denom.rep)
# multiply the coefficients with lcm
for i, j in enumerate(list_of_coeff):
list_of_coeff[i] = j * lcm_denom
gcd_numer = base((list_of_coeff[-1].numer() / list_of_coeff[-1].denom()).rep)
# gcd of numerators in the coefficients
for i in num:
gcd_numer = i.gcd(gcd_numer)
gcd_numer = K.new(gcd_numer.rep)
# divide all the coefficients by the gcd
for i, j in enumerate(list_of_coeff):
frac_ans = j / gcd_numer
list_of_coeff[i] = base((frac_ans.numer() / frac_ans.denom()).rep)
return DifferentialOperator(list_of_coeff, parent)
def _derivate_diff_eq(listofpoly):
"""
Let a differential equation a0(x)y(x) + a1(x)y'(x) + ... = 0
where a0, a1,... are polynomials or rational functions. The function
returns b0, b1, b2... such that the differential equation
b0(x)y(x) + b1(x)y'(x) +... = 0 is formed after differentiating the
former equation.
"""
sol = []
a = len(listofpoly) - 1
sol.append(DMFdiff(listofpoly[0]))
for i, j in enumerate(listofpoly[1:]):
sol.append(DMFdiff(j) + listofpoly[i])
sol.append(listofpoly[a])
return sol
def _hyper_to_meijerg(func):
"""
Converts a `hyper` to meijerg.
"""
ap = func.ap
bq = func.bq
ispoly = any(i <= 0 and int(i) == i for i in ap)
if ispoly:
return hyperexpand(func)
z = func.args[2]
# parameters of the `meijerg` function.
an = (1 - i for i in ap)
anp = ()
bm = (S.Zero, )
bmq = (1 - i for i in bq)
k = S.One
for i in bq:
k = k * gamma(i)
for i in ap:
k = k / gamma(i)
return k * meijerg(an, anp, bm, bmq, -z)
def _add_lists(list1, list2):
"""Takes polynomial sequences of two annihilators a and b and returns
the list of polynomials of sum of a and b.
"""
if len(list1) <= len(list2):
sol = [a + b for a, b in zip(list1, list2)] + list2[len(list1):]
else:
sol = [a + b for a, b in zip(list1, list2)] + list1[len(list2):]
return sol
def _extend_y0(Holonomic, n):
"""
Tries to find more initial conditions by substituting the initial
value point in the differential equation.
"""
if Holonomic.annihilator.is_singular(Holonomic.x0) or Holonomic.is_singularics() == True:
return Holonomic.y0
annihilator = Holonomic.annihilator
a = annihilator.order
listofpoly = []
y0 = Holonomic.y0
R = annihilator.parent.base
K = R.get_field()
for i, j in enumerate(annihilator.listofpoly):
if isinstance(j, annihilator.parent.base.dtype):
listofpoly.append(K.new(j.rep))
if len(y0) < a or n <= len(y0):
return y0
else:
list_red = [-listofpoly[i] / listofpoly[a]
for i in range(a)]
if len(y0) > a:
y1 = [y0[i] for i in range(a)]
else:
y1 = [i for i in y0]
for i in range(n - a):
sol = 0
for a, b in zip(y1, list_red):
r = DMFsubs(b, Holonomic.x0)
if not getattr(r, 'is_finite', True):
return y0
if isinstance(r, (PolyElement, FracElement)):
r = r.as_expr()
sol += a * r
y1.append(sol)
list_red = _derivate_diff_eq(list_red)
return y0 + y1[len(y0):]
def DMFdiff(frac):
# differentiate a DMF object represented as p/q
if not isinstance(frac, DMF):
return frac.diff()
K = frac.ring
p = K.numer(frac)
q = K.denom(frac)
sol_num = - p * q.diff() + q * p.diff()
sol_denom = q**2
return K((sol_num.rep, sol_denom.rep))
def DMFsubs(frac, x0, mpm=False):
# substitute the point x0 in DMF object of the form p/q
if not isinstance(frac, DMF):
return frac
p = frac.num
q = frac.den
sol_p = S.Zero
sol_q = S.Zero
if mpm:
from mpmath import mp
for i, j in enumerate(reversed(p)):
if mpm:
j = sympify(j)._to_mpmath(mp.prec)
sol_p += j * x0**i
for i, j in enumerate(reversed(q)):
if mpm:
j = sympify(j)._to_mpmath(mp.prec)
sol_q += j * x0**i
if isinstance(sol_p, (PolyElement, FracElement)):
sol_p = sol_p.as_expr()
if isinstance(sol_q, (PolyElement, FracElement)):
sol_q = sol_q.as_expr()
return sol_p / sol_q
def _convert_poly_rat_alg(func, x, x0=0, y0=None, lenics=None, domain=QQ, initcond=True):
"""
Converts polynomials, rationals and algebraic functions to holonomic.
"""
ispoly = func.is_polynomial()
if not ispoly:
israt = func.is_rational_function()
else:
israt = True
if not (ispoly or israt):
basepoly, ratexp = func.as_base_exp()
if basepoly.is_polynomial() and ratexp.is_Number:
if isinstance(ratexp, Float):
ratexp = nsimplify(ratexp)
m, n = ratexp.p, ratexp.q
is_alg = True
else:
is_alg = False
else:
is_alg = True
if not (ispoly or israt or is_alg):
return None
R = domain.old_poly_ring(x)
_, Dx = DifferentialOperators(R, 'Dx')
# if the function is constant
if not func.has(x):
return HolonomicFunction(Dx, x, 0, [func])
if ispoly:
# differential equation satisfied by polynomial
sol = func * Dx - func.diff(x)
sol = _normalize(sol.listofpoly, sol.parent, negative=False)
is_singular = sol.is_singular(x0)
# try to compute the conditions for singular points
if y0 is None and x0 == 0 and is_singular:
rep = R.from_sympy(func).rep
for i, j in enumerate(reversed(rep)):
if j == 0:
continue
else:
coeff = list(reversed(rep))[i:]
indicial = i
break
for i, j in enumerate(coeff):
if isinstance(j, (PolyElement, FracElement)):
coeff[i] = j.as_expr()
y0 = {indicial: S(coeff)}
elif israt:
p, q = func.as_numer_denom()
# differential equation satisfied by rational
sol = p * q * Dx + p * q.diff(x) - q * p.diff(x)
sol = _normalize(sol.listofpoly, sol.parent, negative=False)
elif is_alg:
sol = n * (x / m) * Dx - 1
sol = HolonomicFunction(sol, x).composition(basepoly).annihilator
is_singular = sol.is_singular(x0)
# try to compute the conditions for singular points
if y0 is None and x0 == 0 and is_singular and \
(lenics is None or lenics <= 1):
rep = R.from_sympy(basepoly).rep
for i, j in enumerate(reversed(rep)):
if j == 0:
continue
if isinstance(j, (PolyElement, FracElement)):
j = j.as_expr()
coeff = S(j)**ratexp
indicial = S(i) * ratexp
break
if isinstance(coeff, (PolyElement, FracElement)):
coeff = coeff.as_expr()
y0 = {indicial: S([coeff])}
if y0 or not initcond:
return HolonomicFunction(sol, x, x0, y0)
if not lenics:
lenics = sol.order
if sol.is_singular(x0):
r = HolonomicFunction(sol, x, x0)._indicial()
l = list(r)
if len(r) == 1 and r[l[0]] == S.One:
r = l[0]
g = func / (x - x0)**r
singular_ics = _find_conditions(g, x, x0, lenics)
singular_ics = [j / factorial(i) for i, j in enumerate(singular_ics)]
y0 = {r:singular_ics}
return HolonomicFunction(sol, x, x0, y0)
y0 = _find_conditions(func, x, x0, lenics)
while not y0:
x0 += 1
y0 = _find_conditions(func, x, x0, lenics)
return HolonomicFunction(sol, x, x0, y0)
def _convert_meijerint(func, x, initcond=True, domain=QQ):
args = meijerint._rewrite1(func, x)
if args:
fac, po, g, _ = args
else:
return None
# lists for sum of meijerg functions
fac_list = [fac * i[0] for i in g]
t = po.as_base_exp()
s = t[1] if t[0] == x else S.Zero
po_list = [s + i[1] for i in g]
G_list = [i[2] for i in g]
# finds meijerg representation of x**s * meijerg(a1 ... ap, b1 ... bq, z)
def _shift(func, s):
z = func.args[-1]
if z.has(I):
z = z.subs(exp_polar, exp)
d = z.collect(x, evaluate=False)
b = list(d)[0]
a = d[b]
t = b.as_base_exp()
b = t[1] if t[0] == x else S.Zero
r = s / b
an = (i + r for i in func.args[0][0])
ap = (i + r for i in func.args[0][1])
bm = (i + r for i in func.args[1][0])
bq = (i + r for i in func.args[1][1])
return a**-r, meijerg((an, ap), (bm, bq), z)
coeff, m = _shift(G_list[0], po_list[0])
sol = fac_list[0] * coeff * from_meijerg(m, initcond=initcond, domain=domain)
# add all the meijerg functions after converting to holonomic
for i in range(1, len(G_list)):
coeff, m = _shift(G_list[i], po_list[i])
sol += fac_list[i] * coeff * from_meijerg(m, initcond=initcond, domain=domain)
return sol
def _create_table(table, domain=QQ):
"""
Creates the look-up table. For a similar implementation
see meijerint._create_lookup_table.
"""
def add(formula, annihilator, arg, x0=0, y0=[]):
"""
Adds a formula in the dictionary
"""
table.setdefault(_mytype(formula, x_1), []).append((formula,
HolonomicFunction(annihilator, arg, x0, y0)))
R = domain.old_poly_ring(x_1)
_, Dx = DifferentialOperators(R, 'Dx')
from sympy import (sin, cos, exp, log, erf, sqrt, pi,
sinh, cosh, sinc, erfc, Si, Ci, Shi, erfi)
# add some basic functions
add(sin(x_1), Dx**2 + 1, x_1, 0, [0, 1])
add(cos(x_1), Dx**2 + 1, x_1, 0, [1, 0])
add(exp(x_1), Dx - 1, x_1, 0, 1)
add(log(x_1), Dx + x_1*Dx**2, x_1, 1, [0, 1])
add(erf(x_1), 2*x_1*Dx + Dx**2, x_1, 0, [0, 2/sqrt(pi)])
add(erfc(x_1), 2*x_1*Dx + Dx**2, x_1, 0, [1, -2/sqrt(pi)])
add(erfi(x_1), -2*x_1*Dx + Dx**2, x_1, 0, [0, 2/sqrt(pi)])
add(sinh(x_1), Dx**2 - 1, x_1, 0, [0, 1])
add(cosh(x_1), Dx**2 - 1, x_1, 0, [1, 0])
add(sinc(x_1), x_1 + 2*Dx + x_1*Dx**2, x_1)
add(Si(x_1), x_1*Dx + 2*Dx**2 + x_1*Dx**3, x_1)
add(Ci(x_1), x_1*Dx + 2*Dx**2 + x_1*Dx**3, x_1)
add(Shi(x_1), -x_1*Dx + 2*Dx**2 + x_1*Dx**3, x_1)
def _find_conditions(func, x, x0, order):
y0 = []
for i in range(order):
val = func.subs(x, x0)
if isinstance(val, NaN):
val = limit(func, x, x0)
if val.is_finite is False or isinstance(val, NaN):
return None
y0.append(val)
func = func.diff(x)
return y0
|
9e010bca1186d6d4aa2c5c945edac1b5bd5b5982bf4cc764f5af216889e4a126 | from mpmath.matrices.matrices import _matrix
from sympy.core import Basic, Dict, Tuple
from sympy.core.numbers import Integer
from sympy.core.cache import cacheit
from sympy.core.sympify import converter as sympify_converter, _sympify
from sympy.matrices.dense import DenseMatrix
from sympy.matrices.expressions import MatrixExpr
from sympy.matrices.matrices import MatrixBase
from sympy.matrices.repmatrix import RepMatrix
from sympy.matrices.sparse import SparseMatrix
from sympy.multipledispatch import dispatch
def sympify_matrix(arg):
return arg.as_immutable()
sympify_converter[MatrixBase] = sympify_matrix
def sympify_mpmath_matrix(arg):
mat = [_sympify(x) for x in arg]
return ImmutableDenseMatrix(arg.rows, arg.cols, mat)
sympify_converter[_matrix] = sympify_mpmath_matrix
class ImmutableRepMatrix(RepMatrix, MatrixExpr):
"""Immutable matrix based on RepMatrix
Uses DomainMAtrix as the internal representation.
"""
#
# This is a subclass of RepMatrix that adds/overrides some methods to make
# the instances Basic and immutable. ImmutableRepMatrix is a superclass for
# both ImmutableDenseMatrix and ImmutableSparseMatrix.
#
def __new__(cls, *args, **kwargs):
return cls._new(*args, **kwargs)
__hash__ = MatrixExpr.__hash__
def copy(self):
return self
@property
def cols(self):
return self._cols
@property
def rows(self):
return self._rows
@property
def shape(self):
return self._rows, self._cols
def as_immutable(self):
return self
def _entry(self, i, j, **kwargs):
return self[i, j]
def __setitem__(self, *args):
raise TypeError("Cannot set values of {}".format(self.__class__))
def is_diagonalizable(self, reals_only=False, **kwargs):
return super().is_diagonalizable(
reals_only=reals_only, **kwargs)
is_diagonalizable.__doc__ = SparseMatrix.is_diagonalizable.__doc__
is_diagonalizable = cacheit(is_diagonalizable)
class ImmutableDenseMatrix(DenseMatrix, ImmutableRepMatrix): # type: ignore
"""Create an immutable version of a matrix.
Examples
========
>>> from sympy import eye
>>> from sympy.matrices import ImmutableMatrix
>>> ImmutableMatrix(eye(3))
Matrix([
[1, 0, 0],
[0, 1, 0],
[0, 0, 1]])
>>> _[0, 0] = 42
Traceback (most recent call last):
...
TypeError: Cannot set values of ImmutableDenseMatrix
"""
# MatrixExpr is set as NotIterable, but we want explicit matrices to be
# iterable
_iterable = True
_class_priority = 8
_op_priority = 10.001
@classmethod
def _new(cls, *args, **kwargs):
if len(args) == 1 and isinstance(args[0], ImmutableDenseMatrix):
return args[0]
if kwargs.get('copy', True) is False:
if len(args) != 3:
raise TypeError("'copy=False' requires a matrix be initialized as rows,cols,[list]")
rows, cols, flat_list = args
else:
rows, cols, flat_list = cls._handle_creation_inputs(*args, **kwargs)
flat_list = list(flat_list) # create a shallow copy
rep = cls._flat_list_to_DomainMatrix(rows, cols, flat_list)
return cls._fromrep(rep)
@classmethod
def _fromrep(cls, rep):
rows, cols = rep.shape
flat_list = rep.to_sympy().to_list_flat()
obj = Basic.__new__(cls,
Integer(rows),
Integer(cols),
Tuple(*flat_list, sympify=False))
obj._rows = rows
obj._cols = cols
obj._rep = rep
return obj
# make sure ImmutableDenseMatrix is aliased as ImmutableMatrix
ImmutableMatrix = ImmutableDenseMatrix
class ImmutableSparseMatrix(SparseMatrix, ImmutableRepMatrix): # type:ignore
"""Create an immutable version of a sparse matrix.
Examples
========
>>> from sympy import eye
>>> from sympy.matrices.immutable import ImmutableSparseMatrix
>>> ImmutableSparseMatrix(1, 1, {})
Matrix([[0]])
>>> ImmutableSparseMatrix(eye(3))
Matrix([
[1, 0, 0],
[0, 1, 0],
[0, 0, 1]])
>>> _[0, 0] = 42
Traceback (most recent call last):
...
TypeError: Cannot set values of ImmutableSparseMatrix
>>> _.shape
(3, 3)
"""
is_Matrix = True
_class_priority = 9
@classmethod
def _new(cls, *args, **kwargs):
rows, cols, smat = cls._handle_creation_inputs(*args, **kwargs)
rep = cls._smat_to_DomainMatrix(rows, cols, smat)
return cls._fromrep(rep)
@classmethod
def _fromrep(cls, rep):
rows, cols = rep.shape
smat = rep.to_sympy().to_dok()
obj = Basic.__new__(cls, Integer(rows), Integer(cols), Dict(smat))
obj._rows = rows
obj._cols = cols
obj._rep = rep
return obj
@dispatch(ImmutableDenseMatrix, ImmutableDenseMatrix)
def _eval_is_eq(lhs, rhs): # noqa:F811
"""Helper method for Equality with matrices.sympy.
Relational automatically converts matrices to ImmutableDenseMatrix
instances, so this method only applies here. Returns True if the
matrices are definitively the same, False if they are definitively
different, and None if undetermined (e.g. if they contain Symbols).
Returning None triggers default handling of Equalities.
"""
if lhs.shape != rhs.shape:
return False
return (lhs - rhs).is_zero_matrix
|
3bbdc834a01b4e99f335d67bcb4f28c3d5360a6029767ed2f4d12c03d2d1f974 | from sympy.utilities.iterables import \
flatten, connected_components, strongly_connected_components
from .common import NonSquareMatrixError
def _connected_components(M):
"""Returns the list of connected vertices of the graph when
a square matrix is viewed as a weighted graph.
Examples
========
>>> from sympy import Matrix
>>> A = Matrix([
... [66, 0, 0, 68, 0, 0, 0, 0, 67],
... [0, 55, 0, 0, 0, 0, 54, 53, 0],
... [0, 0, 0, 0, 1, 2, 0, 0, 0],
... [86, 0, 0, 88, 0, 0, 0, 0, 87],
... [0, 0, 10, 0, 11, 12, 0, 0, 0],
... [0, 0, 20, 0, 21, 22, 0, 0, 0],
... [0, 45, 0, 0, 0, 0, 44, 43, 0],
... [0, 35, 0, 0, 0, 0, 34, 33, 0],
... [76, 0, 0, 78, 0, 0, 0, 0, 77]])
>>> A.connected_components()
[[0, 3, 8], [1, 6, 7], [2, 4, 5]]
Notes
=====
Even if any symbolic elements of the matrix can be indeterminate
to be zero mathematically, this only takes the account of the
structural aspect of the matrix, so they will considered to be
nonzero.
"""
if not M.is_square:
raise NonSquareMatrixError
V = range(M.rows)
E = sorted(M.todok().keys())
return connected_components((V, E))
def _strongly_connected_components(M):
"""Returns the list of strongly connected vertices of the graph when
a square matrix is viewed as a weighted graph.
Examples
========
>>> from sympy import Matrix
>>> A = Matrix([
... [44, 0, 0, 0, 43, 0, 45, 0, 0],
... [0, 66, 62, 61, 0, 68, 0, 60, 67],
... [0, 0, 22, 21, 0, 0, 0, 20, 0],
... [0, 0, 12, 11, 0, 0, 0, 10, 0],
... [34, 0, 0, 0, 33, 0, 35, 0, 0],
... [0, 86, 82, 81, 0, 88, 0, 80, 87],
... [54, 0, 0, 0, 53, 0, 55, 0, 0],
... [0, 0, 2, 1, 0, 0, 0, 0, 0],
... [0, 76, 72, 71, 0, 78, 0, 70, 77]])
>>> A.strongly_connected_components()
[[0, 4, 6], [2, 3, 7], [1, 5, 8]]
"""
if not M.is_square:
raise NonSquareMatrixError
# RepMatrix uses the more efficient DomainMatrix.scc() method
rep = getattr(M, '_rep', None)
if rep is not None:
return rep.scc()
V = range(M.rows)
E = sorted(M.todok().keys())
return strongly_connected_components((V, E))
def _connected_components_decomposition(M):
"""Decomposes a square matrix into block diagonal form only
using the permutations.
Explanation
===========
The decomposition is in a form of $A = P^{-1} B P$ where $P$ is a
permutation matrix and $B$ is a block diagonal matrix.
Returns
=======
P, B : PermutationMatrix, BlockDiagMatrix
*P* is a permutation matrix for the similarity transform
as in the explanation. And *B* is the block diagonal matrix of
the result of the permutation.
If you would like to get the diagonal blocks from the
BlockDiagMatrix, see
:meth:`~sympy.matrices.expressions.blockmatrix.BlockDiagMatrix.get_diag_blocks`.
Examples
========
>>> from sympy import Matrix, pprint
>>> A = Matrix([
... [66, 0, 0, 68, 0, 0, 0, 0, 67],
... [0, 55, 0, 0, 0, 0, 54, 53, 0],
... [0, 0, 0, 0, 1, 2, 0, 0, 0],
... [86, 0, 0, 88, 0, 0, 0, 0, 87],
... [0, 0, 10, 0, 11, 12, 0, 0, 0],
... [0, 0, 20, 0, 21, 22, 0, 0, 0],
... [0, 45, 0, 0, 0, 0, 44, 43, 0],
... [0, 35, 0, 0, 0, 0, 34, 33, 0],
... [76, 0, 0, 78, 0, 0, 0, 0, 77]])
>>> P, B = A.connected_components_decomposition()
>>> pprint(P)
PermutationMatrix((1 3)(2 8 5 7 4 6))
>>> pprint(B)
[[66 68 67] ]
[[ ] ]
[[86 88 87] 0 0 ]
[[ ] ]
[[76 78 77] ]
[ ]
[ [55 54 53] ]
[ [ ] ]
[ 0 [45 44 43] 0 ]
[ [ ] ]
[ [35 34 33] ]
[ ]
[ [0 1 2 ]]
[ [ ]]
[ 0 0 [10 11 12]]
[ [ ]]
[ [20 21 22]]
>>> P = P.as_explicit()
>>> B = B.as_explicit()
>>> P.T*B*P == A
True
Notes
=====
This problem corresponds to the finding of the connected components
of a graph, when a matrix is viewed as a weighted graph.
"""
from sympy.combinatorics.permutations import Permutation
from sympy.matrices.expressions.blockmatrix import BlockDiagMatrix
from sympy.matrices.expressions.permutation import PermutationMatrix
iblocks = M.connected_components()
p = Permutation(flatten(iblocks))
P = PermutationMatrix(p)
blocks = []
for b in iblocks:
blocks.append(M[b, b])
B = BlockDiagMatrix(*blocks)
return P, B
def _strongly_connected_components_decomposition(M, lower=True):
"""Decomposes a square matrix into block triangular form only
using the permutations.
Explanation
===========
The decomposition is in a form of $A = P^{-1} B P$ where $P$ is a
permutation matrix and $B$ is a block diagonal matrix.
Parameters
==========
lower : bool
Makes $B$ lower block triangular when ``True``.
Otherwise, makes $B$ upper block triangular.
Returns
=======
P, B : PermutationMatrix, BlockMatrix
*P* is a permutation matrix for the similarity transform
as in the explanation. And *B* is the block triangular matrix of
the result of the permutation.
Examples
========
>>> from sympy import Matrix, pprint
>>> A = Matrix([
... [44, 0, 0, 0, 43, 0, 45, 0, 0],
... [0, 66, 62, 61, 0, 68, 0, 60, 67],
... [0, 0, 22, 21, 0, 0, 0, 20, 0],
... [0, 0, 12, 11, 0, 0, 0, 10, 0],
... [34, 0, 0, 0, 33, 0, 35, 0, 0],
... [0, 86, 82, 81, 0, 88, 0, 80, 87],
... [54, 0, 0, 0, 53, 0, 55, 0, 0],
... [0, 0, 2, 1, 0, 0, 0, 0, 0],
... [0, 76, 72, 71, 0, 78, 0, 70, 77]])
A lower block triangular decomposition:
>>> P, B = A.strongly_connected_components_decomposition()
>>> pprint(P)
PermutationMatrix((8)(1 4 3 2 6)(5 7))
>>> pprint(B)
[[44 43 45] [0 0 0] [0 0 0] ]
[[ ] [ ] [ ] ]
[[34 33 35] [0 0 0] [0 0 0] ]
[[ ] [ ] [ ] ]
[[54 53 55] [0 0 0] [0 0 0] ]
[ ]
[ [0 0 0] [22 21 20] [0 0 0] ]
[ [ ] [ ] [ ] ]
[ [0 0 0] [12 11 10] [0 0 0] ]
[ [ ] [ ] [ ] ]
[ [0 0 0] [2 1 0 ] [0 0 0] ]
[ ]
[ [0 0 0] [62 61 60] [66 68 67]]
[ [ ] [ ] [ ]]
[ [0 0 0] [82 81 80] [86 88 87]]
[ [ ] [ ] [ ]]
[ [0 0 0] [72 71 70] [76 78 77]]
>>> P = P.as_explicit()
>>> B = B.as_explicit()
>>> P.T * B * P == A
True
An upper block triangular decomposition:
>>> P, B = A.strongly_connected_components_decomposition(lower=False)
>>> pprint(P)
PermutationMatrix((0 1 5 7 4 3 2 8 6))
>>> pprint(B)
[[66 68 67] [62 61 60] [0 0 0] ]
[[ ] [ ] [ ] ]
[[86 88 87] [82 81 80] [0 0 0] ]
[[ ] [ ] [ ] ]
[[76 78 77] [72 71 70] [0 0 0] ]
[ ]
[ [0 0 0] [22 21 20] [0 0 0] ]
[ [ ] [ ] [ ] ]
[ [0 0 0] [12 11 10] [0 0 0] ]
[ [ ] [ ] [ ] ]
[ [0 0 0] [2 1 0 ] [0 0 0] ]
[ ]
[ [0 0 0] [0 0 0] [44 43 45]]
[ [ ] [ ] [ ]]
[ [0 0 0] [0 0 0] [34 33 35]]
[ [ ] [ ] [ ]]
[ [0 0 0] [0 0 0] [54 53 55]]
>>> P = P.as_explicit()
>>> B = B.as_explicit()
>>> P.T * B * P == A
True
"""
from sympy.combinatorics.permutations import Permutation
from sympy.matrices.expressions.blockmatrix import BlockMatrix
from sympy.matrices.expressions.permutation import PermutationMatrix
iblocks = M.strongly_connected_components()
if not lower:
iblocks = list(reversed(iblocks))
p = Permutation(flatten(iblocks))
P = PermutationMatrix(p)
rows = []
for a in iblocks:
cols = []
for b in iblocks:
cols.append(M[a, b])
rows.append(cols)
B = BlockMatrix(rows)
return P, B
|
1c3837c96feaf7fd4b2756855e57060f8f01097b25c171d3034717abf0fca005 | """
Basic methods common to all matrices to be used
when creating more advanced matrices (e.g., matrices over rings,
etc.).
"""
from collections import defaultdict
from collections.abc import Iterable
from inspect import isfunction
from functools import reduce
from sympy.core.logic import FuzzyBool
from sympy.assumptions.refine import refine
from sympy.core import SympifyError, Add
from sympy.core.basic import Atom
from sympy.core.compatibility import as_int, is_sequence
from sympy.core.decorators import call_highest_priority
from sympy.core.kind import Kind, NumberKind
from sympy.core.logic import fuzzy_and
from sympy.core.singleton import S
from sympy.core.symbol import Symbol
from sympy.core.sympify import sympify
from sympy.functions import Abs
from sympy.polys.polytools import Poly
from sympy.simplify import simplify as _simplify
from sympy.simplify.simplify import dotprodsimp as _dotprodsimp
from sympy.utilities.exceptions import SymPyDeprecationWarning
from sympy.utilities.iterables import flatten
from sympy.utilities.misc import filldedent
from sympy.tensor.array import NDimArray
from .utilities import _get_intermediate_simp_bool
class MatrixError(Exception):
pass
class ShapeError(ValueError, MatrixError):
"""Wrong matrix shape"""
pass
class NonSquareMatrixError(ShapeError):
pass
class NonInvertibleMatrixError(ValueError, MatrixError):
"""The matrix in not invertible (division by multidimensional zero error)."""
pass
class NonPositiveDefiniteMatrixError(ValueError, MatrixError):
"""The matrix is not a positive-definite matrix."""
pass
class MatrixRequired:
"""All subclasses of matrix objects must implement the
required matrix properties listed here."""
rows = None # type: int
cols = None # type: int
_simplify = None
@classmethod
def _new(cls, *args, **kwargs):
"""`_new` must, at minimum, be callable as
`_new(rows, cols, mat) where mat is a flat list of the
elements of the matrix."""
raise NotImplementedError("Subclasses must implement this.")
def __eq__(self, other):
raise NotImplementedError("Subclasses must implement this.")
def __getitem__(self, key):
"""Implementations of __getitem__ should accept ints, in which
case the matrix is indexed as a flat list, tuples (i,j) in which
case the (i,j) entry is returned, slices, or mixed tuples (a,b)
where a and b are any combintion of slices and integers."""
raise NotImplementedError("Subclasses must implement this.")
def __len__(self):
"""The total number of entries in the matrix."""
raise NotImplementedError("Subclasses must implement this.")
@property
def shape(self):
raise NotImplementedError("Subclasses must implement this.")
class MatrixShaping(MatrixRequired):
"""Provides basic matrix shaping and extracting of submatrices"""
def _eval_col_del(self, col):
def entry(i, j):
return self[i, j] if j < col else self[i, j + 1]
return self._new(self.rows, self.cols - 1, entry)
def _eval_col_insert(self, pos, other):
def entry(i, j):
if j < pos:
return self[i, j]
elif pos <= j < pos + other.cols:
return other[i, j - pos]
return self[i, j - other.cols]
return self._new(self.rows, self.cols + other.cols,
lambda i, j: entry(i, j))
def _eval_col_join(self, other):
rows = self.rows
def entry(i, j):
if i < rows:
return self[i, j]
return other[i - rows, j]
return classof(self, other)._new(self.rows + other.rows, self.cols,
lambda i, j: entry(i, j))
def _eval_extract(self, rowsList, colsList):
mat = list(self)
cols = self.cols
indices = (i * cols + j for i in rowsList for j in colsList)
return self._new(len(rowsList), len(colsList),
list(mat[i] for i in indices))
def _eval_get_diag_blocks(self):
sub_blocks = []
def recurse_sub_blocks(M):
i = 1
while i <= M.shape[0]:
if i == 1:
to_the_right = M[0, i:]
to_the_bottom = M[i:, 0]
else:
to_the_right = M[:i, i:]
to_the_bottom = M[i:, :i]
if any(to_the_right) or any(to_the_bottom):
i += 1
continue
else:
sub_blocks.append(M[:i, :i])
if M.shape == M[:i, :i].shape:
return
else:
recurse_sub_blocks(M[i:, i:])
return
recurse_sub_blocks(self)
return sub_blocks
def _eval_row_del(self, row):
def entry(i, j):
return self[i, j] if i < row else self[i + 1, j]
return self._new(self.rows - 1, self.cols, entry)
def _eval_row_insert(self, pos, other):
entries = list(self)
insert_pos = pos * self.cols
entries[insert_pos:insert_pos] = list(other)
return self._new(self.rows + other.rows, self.cols, entries)
def _eval_row_join(self, other):
cols = self.cols
def entry(i, j):
if j < cols:
return self[i, j]
return other[i, j - cols]
return classof(self, other)._new(self.rows, self.cols + other.cols,
lambda i, j: entry(i, j))
def _eval_tolist(self):
return [list(self[i,:]) for i in range(self.rows)]
def _eval_todok(self):
dok = {}
rows, cols = self.shape
for i in range(rows):
for j in range(cols):
val = self[i, j]
if val != self.zero:
dok[i, j] = val
return dok
def _eval_vec(self):
rows = self.rows
def entry(n, _):
# we want to read off the columns first
j = n // rows
i = n - j * rows
return self[i, j]
return self._new(len(self), 1, entry)
def _eval_vech(self, diagonal):
c = self.cols
v = []
if diagonal:
for j in range(c):
for i in range(j, c):
v.append(self[i, j])
else:
for j in range(c):
for i in range(j + 1, c):
v.append(self[i, j])
return self._new(len(v), 1, v)
def col_del(self, col):
"""Delete the specified column."""
if col < 0:
col += self.cols
if not 0 <= col < self.cols:
raise IndexError("Column {} is out of range.".format(col))
return self._eval_col_del(col)
def col_insert(self, pos, other):
"""Insert one or more columns at the given column position.
Examples
========
>>> from sympy import zeros, ones
>>> M = zeros(3)
>>> V = ones(3, 1)
>>> M.col_insert(1, V)
Matrix([
[0, 1, 0, 0],
[0, 1, 0, 0],
[0, 1, 0, 0]])
See Also
========
col
row_insert
"""
# Allows you to build a matrix even if it is null matrix
if not self:
return type(self)(other)
pos = as_int(pos)
if pos < 0:
pos = self.cols + pos
if pos < 0:
pos = 0
elif pos > self.cols:
pos = self.cols
if self.rows != other.rows:
raise ShapeError(
"`self` and `other` must have the same number of rows.")
return self._eval_col_insert(pos, other)
def col_join(self, other):
"""Concatenates two matrices along self's last and other's first row.
Examples
========
>>> from sympy import zeros, ones
>>> M = zeros(3)
>>> V = ones(1, 3)
>>> M.col_join(V)
Matrix([
[0, 0, 0],
[0, 0, 0],
[0, 0, 0],
[1, 1, 1]])
See Also
========
col
row_join
"""
# A null matrix can always be stacked (see #10770)
if self.rows == 0 and self.cols != other.cols:
return self._new(0, other.cols, []).col_join(other)
if self.cols != other.cols:
raise ShapeError(
"`self` and `other` must have the same number of columns.")
return self._eval_col_join(other)
def col(self, j):
"""Elementary column selector.
Examples
========
>>> from sympy import eye
>>> eye(2).col(0)
Matrix([
[1],
[0]])
See Also
========
row
col_del
col_join
col_insert
"""
return self[:, j]
def extract(self, rowsList, colsList):
"""Return a submatrix by specifying a list of rows and columns.
Negative indices can be given. All indices must be in the range
-n <= i < n where n is the number of rows or columns.
Examples
========
>>> from sympy import Matrix
>>> m = Matrix(4, 3, range(12))
>>> m
Matrix([
[0, 1, 2],
[3, 4, 5],
[6, 7, 8],
[9, 10, 11]])
>>> m.extract([0, 1, 3], [0, 1])
Matrix([
[0, 1],
[3, 4],
[9, 10]])
Rows or columns can be repeated:
>>> m.extract([0, 0, 1], [-1])
Matrix([
[2],
[2],
[5]])
Every other row can be taken by using range to provide the indices:
>>> m.extract(range(0, m.rows, 2), [-1])
Matrix([
[2],
[8]])
RowsList or colsList can also be a list of booleans, in which case
the rows or columns corresponding to the True values will be selected:
>>> m.extract([0, 1, 2, 3], [True, False, True])
Matrix([
[0, 2],
[3, 5],
[6, 8],
[9, 11]])
"""
if not is_sequence(rowsList) or not is_sequence(colsList):
raise TypeError("rowsList and colsList must be iterable")
# ensure rowsList and colsList are lists of integers
if rowsList and all(isinstance(i, bool) for i in rowsList):
rowsList = [index for index, item in enumerate(rowsList) if item]
if colsList and all(isinstance(i, bool) for i in colsList):
colsList = [index for index, item in enumerate(colsList) if item]
# ensure everything is in range
rowsList = [a2idx(k, self.rows) for k in rowsList]
colsList = [a2idx(k, self.cols) for k in colsList]
return self._eval_extract(rowsList, colsList)
def get_diag_blocks(self):
"""Obtains the square sub-matrices on the main diagonal of a square matrix.
Useful for inverting symbolic matrices or solving systems of
linear equations which may be decoupled by having a block diagonal
structure.
Examples
========
>>> from sympy import Matrix
>>> from sympy.abc import x, y, z
>>> A = Matrix([[1, 3, 0, 0], [y, z*z, 0, 0], [0, 0, x, 0], [0, 0, 0, 0]])
>>> a1, a2, a3 = A.get_diag_blocks()
>>> a1
Matrix([
[1, 3],
[y, z**2]])
>>> a2
Matrix([[x]])
>>> a3
Matrix([[0]])
"""
return self._eval_get_diag_blocks()
@classmethod
def hstack(cls, *args):
"""Return a matrix formed by joining args horizontally (i.e.
by repeated application of row_join).
Examples
========
>>> from sympy.matrices import Matrix, eye
>>> Matrix.hstack(eye(2), 2*eye(2))
Matrix([
[1, 0, 2, 0],
[0, 1, 0, 2]])
"""
if len(args) == 0:
return cls._new()
kls = type(args[0])
return reduce(kls.row_join, args)
def reshape(self, rows, cols):
"""Reshape the matrix. Total number of elements must remain the same.
Examples
========
>>> from sympy import Matrix
>>> m = Matrix(2, 3, lambda i, j: 1)
>>> m
Matrix([
[1, 1, 1],
[1, 1, 1]])
>>> m.reshape(1, 6)
Matrix([[1, 1, 1, 1, 1, 1]])
>>> m.reshape(3, 2)
Matrix([
[1, 1],
[1, 1],
[1, 1]])
"""
if self.rows * self.cols != rows * cols:
raise ValueError("Invalid reshape parameters %d %d" % (rows, cols))
return self._new(rows, cols, lambda i, j: self[i * cols + j])
def row_del(self, row):
"""Delete the specified row."""
if row < 0:
row += self.rows
if not 0 <= row < self.rows:
raise IndexError("Row {} is out of range.".format(row))
return self._eval_row_del(row)
def row_insert(self, pos, other):
"""Insert one or more rows at the given row position.
Examples
========
>>> from sympy import zeros, ones
>>> M = zeros(3)
>>> V = ones(1, 3)
>>> M.row_insert(1, V)
Matrix([
[0, 0, 0],
[1, 1, 1],
[0, 0, 0],
[0, 0, 0]])
See Also
========
row
col_insert
"""
# Allows you to build a matrix even if it is null matrix
if not self:
return self._new(other)
pos = as_int(pos)
if pos < 0:
pos = self.rows + pos
if pos < 0:
pos = 0
elif pos > self.rows:
pos = self.rows
if self.cols != other.cols:
raise ShapeError(
"`self` and `other` must have the same number of columns.")
return self._eval_row_insert(pos, other)
def row_join(self, other):
"""Concatenates two matrices along self's last and rhs's first column
Examples
========
>>> from sympy import zeros, ones
>>> M = zeros(3)
>>> V = ones(3, 1)
>>> M.row_join(V)
Matrix([
[0, 0, 0, 1],
[0, 0, 0, 1],
[0, 0, 0, 1]])
See Also
========
row
col_join
"""
# A null matrix can always be stacked (see #10770)
if self.cols == 0 and self.rows != other.rows:
return self._new(other.rows, 0, []).row_join(other)
if self.rows != other.rows:
raise ShapeError(
"`self` and `rhs` must have the same number of rows.")
return self._eval_row_join(other)
def diagonal(self, k=0):
"""Returns the kth diagonal of self. The main diagonal
corresponds to `k=0`; diagonals above and below correspond to
`k > 0` and `k < 0`, respectively. The values of `self[i, j]`
for which `j - i = k`, are returned in order of increasing
`i + j`, starting with `i + j = |k|`.
Examples
========
>>> from sympy import Matrix
>>> m = Matrix(3, 3, lambda i, j: j - i); m
Matrix([
[ 0, 1, 2],
[-1, 0, 1],
[-2, -1, 0]])
>>> _.diagonal()
Matrix([[0, 0, 0]])
>>> m.diagonal(1)
Matrix([[1, 1]])
>>> m.diagonal(-2)
Matrix([[-2]])
Even though the diagonal is returned as a Matrix, the element
retrieval can be done with a single index:
>>> Matrix.diag(1, 2, 3).diagonal()[1] # instead of [0, 1]
2
See Also
========
diag - to create a diagonal matrix
"""
rv = []
k = as_int(k)
r = 0 if k > 0 else -k
c = 0 if r else k
while True:
if r == self.rows or c == self.cols:
break
rv.append(self[r, c])
r += 1
c += 1
if not rv:
raise ValueError(filldedent('''
The %s diagonal is out of range [%s, %s]''' % (
k, 1 - self.rows, self.cols - 1)))
return self._new(1, len(rv), rv)
def row(self, i):
"""Elementary row selector.
Examples
========
>>> from sympy import eye
>>> eye(2).row(0)
Matrix([[1, 0]])
See Also
========
col
row_del
row_join
row_insert
"""
return self[i, :]
@property
def shape(self):
"""The shape (dimensions) of the matrix as the 2-tuple (rows, cols).
Examples
========
>>> from sympy.matrices import zeros
>>> M = zeros(2, 3)
>>> M.shape
(2, 3)
>>> M.rows
2
>>> M.cols
3
"""
return (self.rows, self.cols)
def todok(self):
"""Return the matrix as dictionary of keys.
Examples
========
>>> from sympy import Matrix
>>> M = Matrix.eye(3)
>>> M.todok()
{(0, 0): 1, (1, 1): 1, (2, 2): 1}
"""
return self._eval_todok()
def tolist(self):
"""Return the Matrix as a nested Python list.
Examples
========
>>> from sympy import Matrix, ones
>>> m = Matrix(3, 3, range(9))
>>> m
Matrix([
[0, 1, 2],
[3, 4, 5],
[6, 7, 8]])
>>> m.tolist()
[[0, 1, 2], [3, 4, 5], [6, 7, 8]]
>>> ones(3, 0).tolist()
[[], [], []]
When there are no rows then it will not be possible to tell how
many columns were in the original matrix:
>>> ones(0, 3).tolist()
[]
"""
if not self.rows:
return []
if not self.cols:
return [[] for i in range(self.rows)]
return self._eval_tolist()
def todod(M):
"""Returns matrix as dict of dicts containing non-zero elements of the Matrix
Examples
========
>>> from sympy import Matrix
>>> A = Matrix([[0, 1],[0, 3]])
>>> A
Matrix([
[0, 1],
[0, 3]])
>>> A.todod()
{0: {1: 1}, 1: {1: 3}}
"""
rowsdict = {}
Mlol = M.tolist()
for i, Mi in enumerate(Mlol):
row = {j: Mij for j, Mij in enumerate(Mi) if Mij}
if row:
rowsdict[i] = row
return rowsdict
def vec(self):
"""Return the Matrix converted into a one column matrix by stacking columns
Examples
========
>>> from sympy import Matrix
>>> m=Matrix([[1, 3], [2, 4]])
>>> m
Matrix([
[1, 3],
[2, 4]])
>>> m.vec()
Matrix([
[1],
[2],
[3],
[4]])
See Also
========
vech
"""
return self._eval_vec()
def vech(self, diagonal=True, check_symmetry=True):
"""Reshapes the matrix into a column vector by stacking the
elements in the lower triangle.
Parameters
==========
diagonal : bool, optional
If ``True``, it includes the diagonal elements.
check_symmetry : bool, optional
If ``True``, it checks whether the matrix is symmetric.
Examples
========
>>> from sympy import Matrix
>>> m=Matrix([[1, 2], [2, 3]])
>>> m
Matrix([
[1, 2],
[2, 3]])
>>> m.vech()
Matrix([
[1],
[2],
[3]])
>>> m.vech(diagonal=False)
Matrix([[2]])
Notes
=====
This should work for symmetric matrices and ``vech`` can
represent symmetric matrices in vector form with less size than
``vec``.
See Also
========
vec
"""
if not self.is_square:
raise NonSquareMatrixError
if check_symmetry and not self.is_symmetric():
raise ValueError("The matrix is not symmetric.")
return self._eval_vech(diagonal)
@classmethod
def vstack(cls, *args):
"""Return a matrix formed by joining args vertically (i.e.
by repeated application of col_join).
Examples
========
>>> from sympy.matrices import Matrix, eye
>>> Matrix.vstack(eye(2), 2*eye(2))
Matrix([
[1, 0],
[0, 1],
[2, 0],
[0, 2]])
"""
if len(args) == 0:
return cls._new()
kls = type(args[0])
return reduce(kls.col_join, args)
class MatrixSpecial(MatrixRequired):
"""Construction of special matrices"""
@classmethod
def _eval_diag(cls, rows, cols, diag_dict):
"""diag_dict is a defaultdict containing
all the entries of the diagonal matrix."""
def entry(i, j):
return diag_dict[(i, j)]
return cls._new(rows, cols, entry)
@classmethod
def _eval_eye(cls, rows, cols):
vals = [cls.zero]*(rows*cols)
vals[::cols+1] = [cls.one]*min(rows, cols)
return cls._new(rows, cols, vals, copy=False)
@classmethod
def _eval_jordan_block(cls, rows, cols, eigenvalue, band='upper'):
if band == 'lower':
def entry(i, j):
if i == j:
return eigenvalue
elif j + 1 == i:
return cls.one
return cls.zero
else:
def entry(i, j):
if i == j:
return eigenvalue
elif i + 1 == j:
return cls.one
return cls.zero
return cls._new(rows, cols, entry)
@classmethod
def _eval_ones(cls, rows, cols):
def entry(i, j):
return cls.one
return cls._new(rows, cols, entry)
@classmethod
def _eval_zeros(cls, rows, cols):
return cls._new(rows, cols, [cls.zero]*(rows*cols), copy=False)
@classmethod
def _eval_wilkinson(cls, n):
def entry(i, j):
return cls.one if i + 1 == j else cls.zero
D = cls._new(2*n + 1, 2*n + 1, entry)
wminus = cls.diag([i for i in range(-n, n + 1)], unpack=True) + D + D.T
wplus = abs(cls.diag([i for i in range(-n, n + 1)], unpack=True)) + D + D.T
return wminus, wplus
@classmethod
def diag(kls, *args, strict=False, unpack=True, rows=None, cols=None, **kwargs):
"""Returns a matrix with the specified diagonal.
If matrices are passed, a block-diagonal matrix
is created (i.e. the "direct sum" of the matrices).
kwargs
======
rows : rows of the resulting matrix; computed if
not given.
cols : columns of the resulting matrix; computed if
not given.
cls : class for the resulting matrix
unpack : bool which, when True (default), unpacks a single
sequence rather than interpreting it as a Matrix.
strict : bool which, when False (default), allows Matrices to
have variable-length rows.
Examples
========
>>> from sympy.matrices import Matrix
>>> Matrix.diag(1, 2, 3)
Matrix([
[1, 0, 0],
[0, 2, 0],
[0, 0, 3]])
The current default is to unpack a single sequence. If this is
not desired, set `unpack=False` and it will be interpreted as
a matrix.
>>> Matrix.diag([1, 2, 3]) == Matrix.diag(1, 2, 3)
True
When more than one element is passed, each is interpreted as
something to put on the diagonal. Lists are converted to
matrices. Filling of the diagonal always continues from
the bottom right hand corner of the previous item: this
will create a block-diagonal matrix whether the matrices
are square or not.
>>> col = [1, 2, 3]
>>> row = [[4, 5]]
>>> Matrix.diag(col, row)
Matrix([
[1, 0, 0],
[2, 0, 0],
[3, 0, 0],
[0, 4, 5]])
When `unpack` is False, elements within a list need not all be
of the same length. Setting `strict` to True would raise a
ValueError for the following:
>>> Matrix.diag([[1, 2, 3], [4, 5], [6]], unpack=False)
Matrix([
[1, 2, 3],
[4, 5, 0],
[6, 0, 0]])
The type of the returned matrix can be set with the ``cls``
keyword.
>>> from sympy.matrices import ImmutableMatrix
>>> from sympy.utilities.misc import func_name
>>> func_name(Matrix.diag(1, cls=ImmutableMatrix))
'ImmutableDenseMatrix'
A zero dimension matrix can be used to position the start of
the filling at the start of an arbitrary row or column:
>>> from sympy import ones
>>> r2 = ones(0, 2)
>>> Matrix.diag(r2, 1, 2)
Matrix([
[0, 0, 1, 0],
[0, 0, 0, 2]])
See Also
========
eye
diagonal - to extract a diagonal
.dense.diag
.expressions.blockmatrix.BlockMatrix
.sparsetools.banded - to create multi-diagonal matrices
"""
from sympy.matrices.matrices import MatrixBase
from sympy.matrices.dense import Matrix
from sympy.matrices.sparse import SparseMatrix
klass = kwargs.get('cls', kls)
if unpack and len(args) == 1 and is_sequence(args[0]) and \
not isinstance(args[0], MatrixBase):
args = args[0]
# fill a default dict with the diagonal entries
diag_entries = defaultdict(int)
rmax = cmax = 0 # keep track of the biggest index seen
for m in args:
if isinstance(m, list):
if strict:
# if malformed, Matrix will raise an error
_ = Matrix(m)
r, c = _.shape
m = _.tolist()
else:
r, c, smat = SparseMatrix._handle_creation_inputs(m)
for (i, j), _ in smat.items():
diag_entries[(i + rmax, j + cmax)] = _
m = [] # to skip process below
elif hasattr(m, 'shape'): # a Matrix
# convert to list of lists
r, c = m.shape
m = m.tolist()
else: # in this case, we're a single value
diag_entries[(rmax, cmax)] = m
rmax += 1
cmax += 1
continue
# process list of lists
for i in range(len(m)):
for j, _ in enumerate(m[i]):
diag_entries[(i + rmax, j + cmax)] = _
rmax += r
cmax += c
if rows is None:
rows, cols = cols, rows
if rows is None:
rows, cols = rmax, cmax
else:
cols = rows if cols is None else cols
if rows < rmax or cols < cmax:
raise ValueError(filldedent('''
The constructed matrix is {} x {} but a size of {} x {}
was specified.'''.format(rmax, cmax, rows, cols)))
return klass._eval_diag(rows, cols, diag_entries)
@classmethod
def eye(kls, rows, cols=None, **kwargs):
"""Returns an identity matrix.
Args
====
rows : rows of the matrix
cols : cols of the matrix (if None, cols=rows)
kwargs
======
cls : class of the returned matrix
"""
if cols is None:
cols = rows
if rows < 0 or cols < 0:
raise ValueError("Cannot create a {} x {} matrix. "
"Both dimensions must be positive".format(rows, cols))
klass = kwargs.get('cls', kls)
rows, cols = as_int(rows), as_int(cols)
return klass._eval_eye(rows, cols)
@classmethod
def jordan_block(kls, size=None, eigenvalue=None, *, band='upper', **kwargs):
"""Returns a Jordan block
Parameters
==========
size : Integer, optional
Specifies the shape of the Jordan block matrix.
eigenvalue : Number or Symbol
Specifies the value for the main diagonal of the matrix.
.. note::
The keyword ``eigenval`` is also specified as an alias
of this keyword, but it is not recommended to use.
We may deprecate the alias in later release.
band : 'upper' or 'lower', optional
Specifies the position of the off-diagonal to put `1` s on.
cls : Matrix, optional
Specifies the matrix class of the output form.
If it is not specified, the class type where the method is
being executed on will be returned.
rows, cols : Integer, optional
Specifies the shape of the Jordan block matrix. See Notes
section for the details of how these key works.
.. note::
This feature will be deprecated in the future.
Returns
=======
Matrix
A Jordan block matrix.
Raises
======
ValueError
If insufficient arguments are given for matrix size
specification, or no eigenvalue is given.
Examples
========
Creating a default Jordan block:
>>> from sympy import Matrix
>>> from sympy.abc import x
>>> Matrix.jordan_block(4, x)
Matrix([
[x, 1, 0, 0],
[0, x, 1, 0],
[0, 0, x, 1],
[0, 0, 0, x]])
Creating an alternative Jordan block matrix where `1` is on
lower off-diagonal:
>>> Matrix.jordan_block(4, x, band='lower')
Matrix([
[x, 0, 0, 0],
[1, x, 0, 0],
[0, 1, x, 0],
[0, 0, 1, x]])
Creating a Jordan block with keyword arguments
>>> Matrix.jordan_block(size=4, eigenvalue=x)
Matrix([
[x, 1, 0, 0],
[0, x, 1, 0],
[0, 0, x, 1],
[0, 0, 0, x]])
Notes
=====
.. note::
This feature will be deprecated in the future.
The keyword arguments ``size``, ``rows``, ``cols`` relates to
the Jordan block size specifications.
If you want to create a square Jordan block, specify either
one of the three arguments.
If you want to create a rectangular Jordan block, specify
``rows`` and ``cols`` individually.
+--------------------------------+---------------------+
| Arguments Given | Matrix Shape |
+----------+----------+----------+----------+----------+
| size | rows | cols | rows | cols |
+==========+==========+==========+==========+==========+
| size | Any | size | size |
+----------+----------+----------+----------+----------+
| | None | ValueError |
| +----------+----------+----------+----------+
| None | rows | None | rows | rows |
| +----------+----------+----------+----------+
| | None | cols | cols | cols |
+ +----------+----------+----------+----------+
| | rows | cols | rows | cols |
+----------+----------+----------+----------+----------+
References
==========
.. [1] https://en.wikipedia.org/wiki/Jordan_matrix
"""
if 'rows' in kwargs or 'cols' in kwargs:
SymPyDeprecationWarning(
feature="Keyword arguments 'rows' or 'cols'",
issue=16102,
useinstead="a more generic banded matrix constructor",
deprecated_since_version="1.4"
).warn()
klass = kwargs.pop('cls', kls)
rows = kwargs.pop('rows', None)
cols = kwargs.pop('cols', None)
eigenval = kwargs.get('eigenval', None)
if eigenvalue is None and eigenval is None:
raise ValueError("Must supply an eigenvalue")
elif eigenvalue != eigenval and None not in (eigenval, eigenvalue):
raise ValueError(
"Inconsistent values are given: 'eigenval'={}, "
"'eigenvalue'={}".format(eigenval, eigenvalue))
else:
if eigenval is not None:
eigenvalue = eigenval
if (size, rows, cols) == (None, None, None):
raise ValueError("Must supply a matrix size")
if size is not None:
rows, cols = size, size
elif rows is not None and cols is None:
cols = rows
elif cols is not None and rows is None:
rows = cols
rows, cols = as_int(rows), as_int(cols)
return klass._eval_jordan_block(rows, cols, eigenvalue, band)
@classmethod
def ones(kls, rows, cols=None, **kwargs):
"""Returns a matrix of ones.
Args
====
rows : rows of the matrix
cols : cols of the matrix (if None, cols=rows)
kwargs
======
cls : class of the returned matrix
"""
if cols is None:
cols = rows
klass = kwargs.get('cls', kls)
rows, cols = as_int(rows), as_int(cols)
return klass._eval_ones(rows, cols)
@classmethod
def zeros(kls, rows, cols=None, **kwargs):
"""Returns a matrix of zeros.
Args
====
rows : rows of the matrix
cols : cols of the matrix (if None, cols=rows)
kwargs
======
cls : class of the returned matrix
"""
if cols is None:
cols = rows
if rows < 0 or cols < 0:
raise ValueError("Cannot create a {} x {} matrix. "
"Both dimensions must be positive".format(rows, cols))
klass = kwargs.get('cls', kls)
rows, cols = as_int(rows), as_int(cols)
return klass._eval_zeros(rows, cols)
@classmethod
def companion(kls, poly):
"""Returns a companion matrix of a polynomial.
Examples
========
>>> from sympy import Matrix, Poly, Symbol, symbols
>>> x = Symbol('x')
>>> c0, c1, c2, c3, c4 = symbols('c0:5')
>>> p = Poly(c0 + c1*x + c2*x**2 + c3*x**3 + c4*x**4 + x**5, x)
>>> Matrix.companion(p)
Matrix([
[0, 0, 0, 0, -c0],
[1, 0, 0, 0, -c1],
[0, 1, 0, 0, -c2],
[0, 0, 1, 0, -c3],
[0, 0, 0, 1, -c4]])
"""
poly = kls._sympify(poly)
if not isinstance(poly, Poly):
raise ValueError("{} must be a Poly instance.".format(poly))
if not poly.is_monic:
raise ValueError("{} must be a monic polynomial.".format(poly))
if not poly.is_univariate:
raise ValueError(
"{} must be a univariate polynomial.".format(poly))
size = poly.degree()
if not size >= 1:
raise ValueError(
"{} must have degree not less than 1.".format(poly))
coeffs = poly.all_coeffs()
def entry(i, j):
if j == size - 1:
return -coeffs[-1 - i]
elif i == j + 1:
return kls.one
return kls.zero
return kls._new(size, size, entry)
@classmethod
def wilkinson(kls, n, **kwargs):
"""Returns two square Wilkinson Matrix of size 2*n + 1
$W_{2n + 1}^-, W_{2n + 1}^+ =$ Wilkinson(n)
Examples
========
>>> from sympy.matrices import Matrix
>>> wminus, wplus = Matrix.wilkinson(3)
>>> wminus
Matrix([
[-3, 1, 0, 0, 0, 0, 0],
[ 1, -2, 1, 0, 0, 0, 0],
[ 0, 1, -1, 1, 0, 0, 0],
[ 0, 0, 1, 0, 1, 0, 0],
[ 0, 0, 0, 1, 1, 1, 0],
[ 0, 0, 0, 0, 1, 2, 1],
[ 0, 0, 0, 0, 0, 1, 3]])
>>> wplus
Matrix([
[3, 1, 0, 0, 0, 0, 0],
[1, 2, 1, 0, 0, 0, 0],
[0, 1, 1, 1, 0, 0, 0],
[0, 0, 1, 0, 1, 0, 0],
[0, 0, 0, 1, 1, 1, 0],
[0, 0, 0, 0, 1, 2, 1],
[0, 0, 0, 0, 0, 1, 3]])
References
==========
.. [1] https://blogs.mathworks.com/cleve/2013/04/15/wilkinsons-matrices-2/
.. [2] J. H. Wilkinson, The Algebraic Eigenvalue Problem, Claredon Press, Oxford, 1965, 662 pp.
"""
klass = kwargs.get('cls', kls)
n = as_int(n)
return klass._eval_wilkinson(n)
class MatrixProperties(MatrixRequired):
"""Provides basic properties of a matrix."""
def _eval_atoms(self, *types):
result = set()
for i in self:
result.update(i.atoms(*types))
return result
def _eval_free_symbols(self):
return set().union(*(i.free_symbols for i in self if i))
def _eval_has(self, *patterns):
return any(a.has(*patterns) for a in self)
def _eval_is_anti_symmetric(self, simpfunc):
if not all(simpfunc(self[i, j] + self[j, i]).is_zero for i in range(self.rows) for j in range(self.cols)):
return False
return True
def _eval_is_diagonal(self):
for i in range(self.rows):
for j in range(self.cols):
if i != j and self[i, j]:
return False
return True
# _eval_is_hermitian is called by some general sympy
# routines and has a different *args signature. Make
# sure the names don't clash by adding `_matrix_` in name.
def _eval_is_matrix_hermitian(self, simpfunc):
mat = self._new(self.rows, self.cols, lambda i, j: simpfunc(self[i, j] - self[j, i].conjugate()))
return mat.is_zero_matrix
def _eval_is_Identity(self) -> FuzzyBool:
def dirac(i, j):
if i == j:
return 1
return 0
return all(self[i, j] == dirac(i, j)
for i in range(self.rows)
for j in range(self.cols))
def _eval_is_lower_hessenberg(self):
return all(self[i, j].is_zero
for i in range(self.rows)
for j in range(i + 2, self.cols))
def _eval_is_lower(self):
return all(self[i, j].is_zero
for i in range(self.rows)
for j in range(i + 1, self.cols))
def _eval_is_symbolic(self):
return self.has(Symbol)
def _eval_is_symmetric(self, simpfunc):
mat = self._new(self.rows, self.cols, lambda i, j: simpfunc(self[i, j] - self[j, i]))
return mat.is_zero_matrix
def _eval_is_zero_matrix(self):
if any(i.is_zero == False for i in self):
return False
if any(i.is_zero is None for i in self):
return None
return True
def _eval_is_upper_hessenberg(self):
return all(self[i, j].is_zero
for i in range(2, self.rows)
for j in range(min(self.cols, (i - 1))))
def _eval_values(self):
return [i for i in self if not i.is_zero]
def _has_positive_diagonals(self):
diagonal_entries = (self[i, i] for i in range(self.rows))
return fuzzy_and(x.is_positive for x in diagonal_entries)
def _has_nonnegative_diagonals(self):
diagonal_entries = (self[i, i] for i in range(self.rows))
return fuzzy_and(x.is_nonnegative for x in diagonal_entries)
def atoms(self, *types):
"""Returns the atoms that form the current object.
Examples
========
>>> from sympy.abc import x, y
>>> from sympy.matrices import Matrix
>>> Matrix([[x]])
Matrix([[x]])
>>> _.atoms()
{x}
>>> Matrix([[x, y], [y, x]])
Matrix([
[x, y],
[y, x]])
>>> _.atoms()
{x, y}
"""
types = tuple(t if isinstance(t, type) else type(t) for t in types)
if not types:
types = (Atom,)
return self._eval_atoms(*types)
@property
def free_symbols(self):
"""Returns the free symbols within the matrix.
Examples
========
>>> from sympy.abc import x
>>> from sympy.matrices import Matrix
>>> Matrix([[x], [1]]).free_symbols
{x}
"""
return self._eval_free_symbols()
def has(self, *patterns):
"""Test whether any subexpression matches any of the patterns.
Examples
========
>>> from sympy import Matrix, SparseMatrix, Float
>>> from sympy.abc import x, y
>>> A = Matrix(((1, x), (0.2, 3)))
>>> B = SparseMatrix(((1, x), (0.2, 3)))
>>> A.has(x)
True
>>> A.has(y)
False
>>> A.has(Float)
True
>>> B.has(x)
True
>>> B.has(y)
False
>>> B.has(Float)
True
"""
return self._eval_has(*patterns)
def is_anti_symmetric(self, simplify=True):
"""Check if matrix M is an antisymmetric matrix,
that is, M is a square matrix with all M[i, j] == -M[j, i].
When ``simplify=True`` (default), the sum M[i, j] + M[j, i] is
simplified before testing to see if it is zero. By default,
the SymPy simplify function is used. To use a custom function
set simplify to a function that accepts a single argument which
returns a simplified expression. To skip simplification, set
simplify to False but note that although this will be faster,
it may induce false negatives.
Examples
========
>>> from sympy import Matrix, symbols
>>> m = Matrix(2, 2, [0, 1, -1, 0])
>>> m
Matrix([
[ 0, 1],
[-1, 0]])
>>> m.is_anti_symmetric()
True
>>> x, y = symbols('x y')
>>> m = Matrix(2, 3, [0, 0, x, -y, 0, 0])
>>> m
Matrix([
[ 0, 0, x],
[-y, 0, 0]])
>>> m.is_anti_symmetric()
False
>>> from sympy.abc import x, y
>>> m = Matrix(3, 3, [0, x**2 + 2*x + 1, y,
... -(x + 1)**2 , 0, x*y,
... -y, -x*y, 0])
Simplification of matrix elements is done by default so even
though two elements which should be equal and opposite wouldn't
pass an equality test, the matrix is still reported as
anti-symmetric:
>>> m[0, 1] == -m[1, 0]
False
>>> m.is_anti_symmetric()
True
If 'simplify=False' is used for the case when a Matrix is already
simplified, this will speed things up. Here, we see that without
simplification the matrix does not appear anti-symmetric:
>>> m.is_anti_symmetric(simplify=False)
False
But if the matrix were already expanded, then it would appear
anti-symmetric and simplification in the is_anti_symmetric routine
is not needed:
>>> m = m.expand()
>>> m.is_anti_symmetric(simplify=False)
True
"""
# accept custom simplification
simpfunc = simplify
if not isfunction(simplify):
simpfunc = _simplify if simplify else lambda x: x
if not self.is_square:
return False
return self._eval_is_anti_symmetric(simpfunc)
def is_diagonal(self):
"""Check if matrix is diagonal,
that is matrix in which the entries outside the main diagonal are all zero.
Examples
========
>>> from sympy import Matrix, diag
>>> m = Matrix(2, 2, [1, 0, 0, 2])
>>> m
Matrix([
[1, 0],
[0, 2]])
>>> m.is_diagonal()
True
>>> m = Matrix(2, 2, [1, 1, 0, 2])
>>> m
Matrix([
[1, 1],
[0, 2]])
>>> m.is_diagonal()
False
>>> m = diag(1, 2, 3)
>>> m
Matrix([
[1, 0, 0],
[0, 2, 0],
[0, 0, 3]])
>>> m.is_diagonal()
True
See Also
========
is_lower
is_upper
sympy.matrices.matrices.MatrixEigen.is_diagonalizable
diagonalize
"""
return self._eval_is_diagonal()
@property
def is_weakly_diagonally_dominant(self):
r"""Tests if the matrix is row weakly diagonally dominant.
Explanation
===========
A $n, n$ matrix $A$ is row weakly diagonally dominant if
.. math::
\left|A_{i, i}\right| \ge \sum_{j = 0, j \neq i}^{n-1}
\left|A_{i, j}\right| \quad {\text{for all }}
i \in \{ 0, ..., n-1 \}
Examples
========
>>> from sympy.matrices import Matrix
>>> A = Matrix([[3, -2, 1], [1, -3, 2], [-1, 2, 4]])
>>> A.is_weakly_diagonally_dominant
True
>>> A = Matrix([[-2, 2, 1], [1, 3, 2], [1, -2, 0]])
>>> A.is_weakly_diagonally_dominant
False
>>> A = Matrix([[-4, 2, 1], [1, 6, 2], [1, -2, 5]])
>>> A.is_weakly_diagonally_dominant
True
Notes
=====
If you want to test whether a matrix is column diagonally
dominant, you can apply the test after transposing the matrix.
"""
if not self.is_square:
return False
rows, cols = self.shape
def test_row(i):
summation = self.zero
for j in range(cols):
if i != j:
summation += Abs(self[i, j])
return (Abs(self[i, i]) - summation).is_nonnegative
return fuzzy_and(test_row(i) for i in range(rows))
@property
def is_strongly_diagonally_dominant(self):
r"""Tests if the matrix is row strongly diagonally dominant.
Explanation
===========
A $n, n$ matrix $A$ is row strongly diagonally dominant if
.. math::
\left|A_{i, i}\right| > \sum_{j = 0, j \neq i}^{n-1}
\left|A_{i, j}\right| \quad {\text{for all }}
i \in \{ 0, ..., n-1 \}
Examples
========
>>> from sympy.matrices import Matrix
>>> A = Matrix([[3, -2, 1], [1, -3, 2], [-1, 2, 4]])
>>> A.is_strongly_diagonally_dominant
False
>>> A = Matrix([[-2, 2, 1], [1, 3, 2], [1, -2, 0]])
>>> A.is_strongly_diagonally_dominant
False
>>> A = Matrix([[-4, 2, 1], [1, 6, 2], [1, -2, 5]])
>>> A.is_strongly_diagonally_dominant
True
Notes
=====
If you want to test whether a matrix is column diagonally
dominant, you can apply the test after transposing the matrix.
"""
if not self.is_square:
return False
rows, cols = self.shape
def test_row(i):
summation = self.zero
for j in range(cols):
if i != j:
summation += Abs(self[i, j])
return (Abs(self[i, i]) - summation).is_positive
return fuzzy_and(test_row(i) for i in range(rows))
@property
def is_hermitian(self):
"""Checks if the matrix is Hermitian.
In a Hermitian matrix element i,j is the complex conjugate of
element j,i.
Examples
========
>>> from sympy.matrices import Matrix
>>> from sympy import I
>>> from sympy.abc import x
>>> a = Matrix([[1, I], [-I, 1]])
>>> a
Matrix([
[ 1, I],
[-I, 1]])
>>> a.is_hermitian
True
>>> a[0, 0] = 2*I
>>> a.is_hermitian
False
>>> a[0, 0] = x
>>> a.is_hermitian
>>> a[0, 1] = a[1, 0]*I
>>> a.is_hermitian
False
"""
if not self.is_square:
return False
return self._eval_is_matrix_hermitian(_simplify)
@property
def is_Identity(self) -> FuzzyBool:
if not self.is_square:
return False
return self._eval_is_Identity()
@property
def is_lower_hessenberg(self):
r"""Checks if the matrix is in the lower-Hessenberg form.
The lower hessenberg matrix has zero entries
above the first superdiagonal.
Examples
========
>>> from sympy.matrices import Matrix
>>> a = Matrix([[1, 2, 0, 0], [5, 2, 3, 0], [3, 4, 3, 7], [5, 6, 1, 1]])
>>> a
Matrix([
[1, 2, 0, 0],
[5, 2, 3, 0],
[3, 4, 3, 7],
[5, 6, 1, 1]])
>>> a.is_lower_hessenberg
True
See Also
========
is_upper_hessenberg
is_lower
"""
return self._eval_is_lower_hessenberg()
@property
def is_lower(self):
"""Check if matrix is a lower triangular matrix. True can be returned
even if the matrix is not square.
Examples
========
>>> from sympy import Matrix
>>> m = Matrix(2, 2, [1, 0, 0, 1])
>>> m
Matrix([
[1, 0],
[0, 1]])
>>> m.is_lower
True
>>> m = Matrix(4, 3, [0, 0, 0, 2, 0, 0, 1, 4 , 0, 6, 6, 5])
>>> m
Matrix([
[0, 0, 0],
[2, 0, 0],
[1, 4, 0],
[6, 6, 5]])
>>> m.is_lower
True
>>> from sympy.abc import x, y
>>> m = Matrix(2, 2, [x**2 + y, y**2 + x, 0, x + y])
>>> m
Matrix([
[x**2 + y, x + y**2],
[ 0, x + y]])
>>> m.is_lower
False
See Also
========
is_upper
is_diagonal
is_lower_hessenberg
"""
return self._eval_is_lower()
@property
def is_square(self):
"""Checks if a matrix is square.
A matrix is square if the number of rows equals the number of columns.
The empty matrix is square by definition, since the number of rows and
the number of columns are both zero.
Examples
========
>>> from sympy import Matrix
>>> a = Matrix([[1, 2, 3], [4, 5, 6]])
>>> b = Matrix([[1, 2, 3], [4, 5, 6], [7, 8, 9]])
>>> c = Matrix([])
>>> a.is_square
False
>>> b.is_square
True
>>> c.is_square
True
"""
return self.rows == self.cols
def is_symbolic(self):
"""Checks if any elements contain Symbols.
Examples
========
>>> from sympy.matrices import Matrix
>>> from sympy.abc import x, y
>>> M = Matrix([[x, y], [1, 0]])
>>> M.is_symbolic()
True
"""
return self._eval_is_symbolic()
def is_symmetric(self, simplify=True):
"""Check if matrix is symmetric matrix,
that is square matrix and is equal to its transpose.
By default, simplifications occur before testing symmetry.
They can be skipped using 'simplify=False'; while speeding things a bit,
this may however induce false negatives.
Examples
========
>>> from sympy import Matrix
>>> m = Matrix(2, 2, [0, 1, 1, 2])
>>> m
Matrix([
[0, 1],
[1, 2]])
>>> m.is_symmetric()
True
>>> m = Matrix(2, 2, [0, 1, 2, 0])
>>> m
Matrix([
[0, 1],
[2, 0]])
>>> m.is_symmetric()
False
>>> m = Matrix(2, 3, [0, 0, 0, 0, 0, 0])
>>> m
Matrix([
[0, 0, 0],
[0, 0, 0]])
>>> m.is_symmetric()
False
>>> from sympy.abc import x, y
>>> m = Matrix(3, 3, [1, x**2 + 2*x + 1, y, (x + 1)**2 , 2, 0, y, 0, 3])
>>> m
Matrix([
[ 1, x**2 + 2*x + 1, y],
[(x + 1)**2, 2, 0],
[ y, 0, 3]])
>>> m.is_symmetric()
True
If the matrix is already simplified, you may speed-up is_symmetric()
test by using 'simplify=False'.
>>> bool(m.is_symmetric(simplify=False))
False
>>> m1 = m.expand()
>>> m1.is_symmetric(simplify=False)
True
"""
simpfunc = simplify
if not isfunction(simplify):
simpfunc = _simplify if simplify else lambda x: x
if not self.is_square:
return False
return self._eval_is_symmetric(simpfunc)
@property
def is_upper_hessenberg(self):
"""Checks if the matrix is the upper-Hessenberg form.
The upper hessenberg matrix has zero entries
below the first subdiagonal.
Examples
========
>>> from sympy.matrices import Matrix
>>> a = Matrix([[1, 4, 2, 3], [3, 4, 1, 7], [0, 2, 3, 4], [0, 0, 1, 3]])
>>> a
Matrix([
[1, 4, 2, 3],
[3, 4, 1, 7],
[0, 2, 3, 4],
[0, 0, 1, 3]])
>>> a.is_upper_hessenberg
True
See Also
========
is_lower_hessenberg
is_upper
"""
return self._eval_is_upper_hessenberg()
@property
def is_upper(self):
"""Check if matrix is an upper triangular matrix. True can be returned
even if the matrix is not square.
Examples
========
>>> from sympy import Matrix
>>> m = Matrix(2, 2, [1, 0, 0, 1])
>>> m
Matrix([
[1, 0],
[0, 1]])
>>> m.is_upper
True
>>> m = Matrix(4, 3, [5, 1, 9, 0, 4 , 6, 0, 0, 5, 0, 0, 0])
>>> m
Matrix([
[5, 1, 9],
[0, 4, 6],
[0, 0, 5],
[0, 0, 0]])
>>> m.is_upper
True
>>> m = Matrix(2, 3, [4, 2, 5, 6, 1, 1])
>>> m
Matrix([
[4, 2, 5],
[6, 1, 1]])
>>> m.is_upper
False
See Also
========
is_lower
is_diagonal
is_upper_hessenberg
"""
return all(self[i, j].is_zero
for i in range(1, self.rows)
for j in range(min(i, self.cols)))
@property
def is_zero_matrix(self):
"""Checks if a matrix is a zero matrix.
A matrix is zero if every element is zero. A matrix need not be square
to be considered zero. The empty matrix is zero by the principle of
vacuous truth. For a matrix that may or may not be zero (e.g.
contains a symbol), this will be None
Examples
========
>>> from sympy import Matrix, zeros
>>> from sympy.abc import x
>>> a = Matrix([[0, 0], [0, 0]])
>>> b = zeros(3, 4)
>>> c = Matrix([[0, 1], [0, 0]])
>>> d = Matrix([])
>>> e = Matrix([[x, 0], [0, 0]])
>>> a.is_zero_matrix
True
>>> b.is_zero_matrix
True
>>> c.is_zero_matrix
False
>>> d.is_zero_matrix
True
>>> e.is_zero_matrix
"""
return self._eval_is_zero_matrix()
def values(self):
"""Return non-zero values of self."""
return self._eval_values()
class MatrixOperations(MatrixRequired):
"""Provides basic matrix shape and elementwise
operations. Should not be instantiated directly."""
def _eval_adjoint(self):
return self.transpose().conjugate()
def _eval_applyfunc(self, f):
out = self._new(self.rows, self.cols, [f(x) for x in self])
return out
def _eval_as_real_imag(self): # type: ignore
from sympy.functions.elementary.complexes import re, im
return (self.applyfunc(re), self.applyfunc(im))
def _eval_conjugate(self):
return self.applyfunc(lambda x: x.conjugate())
def _eval_permute_cols(self, perm):
# apply the permutation to a list
mapping = list(perm)
def entry(i, j):
return self[i, mapping[j]]
return self._new(self.rows, self.cols, entry)
def _eval_permute_rows(self, perm):
# apply the permutation to a list
mapping = list(perm)
def entry(i, j):
return self[mapping[i], j]
return self._new(self.rows, self.cols, entry)
def _eval_trace(self):
return sum(self[i, i] for i in range(self.rows))
def _eval_transpose(self):
return self._new(self.cols, self.rows, lambda i, j: self[j, i])
def adjoint(self):
"""Conjugate transpose or Hermitian conjugation."""
return self._eval_adjoint()
def applyfunc(self, f):
"""Apply a function to each element of the matrix.
Examples
========
>>> from sympy import Matrix
>>> m = Matrix(2, 2, lambda i, j: i*2+j)
>>> m
Matrix([
[0, 1],
[2, 3]])
>>> m.applyfunc(lambda i: 2*i)
Matrix([
[0, 2],
[4, 6]])
"""
if not callable(f):
raise TypeError("`f` must be callable.")
return self._eval_applyfunc(f)
def as_real_imag(self, deep=True, **hints):
"""Returns a tuple containing the (real, imaginary) part of matrix."""
# XXX: Ignoring deep and hints...
return self._eval_as_real_imag()
def conjugate(self):
"""Return the by-element conjugation.
Examples
========
>>> from sympy.matrices import SparseMatrix
>>> from sympy import I
>>> a = SparseMatrix(((1, 2 + I), (3, 4), (I, -I)))
>>> a
Matrix([
[1, 2 + I],
[3, 4],
[I, -I]])
>>> a.C
Matrix([
[ 1, 2 - I],
[ 3, 4],
[-I, I]])
See Also
========
transpose: Matrix transposition
H: Hermite conjugation
sympy.matrices.matrices.MatrixBase.D: Dirac conjugation
"""
return self._eval_conjugate()
def doit(self, **kwargs):
return self.applyfunc(lambda x: x.doit())
def evalf(self, n=15, subs=None, maxn=100, chop=False, strict=False, quad=None, verbose=False):
"""Apply evalf() to each element of self."""
options = {'subs':subs, 'maxn':maxn, 'chop':chop, 'strict':strict,
'quad':quad, 'verbose':verbose}
return self.applyfunc(lambda i: i.evalf(n, **options))
def expand(self, deep=True, modulus=None, power_base=True, power_exp=True,
mul=True, log=True, multinomial=True, basic=True, **hints):
"""Apply core.function.expand to each entry of the matrix.
Examples
========
>>> from sympy.abc import x
>>> from sympy.matrices import Matrix
>>> Matrix(1, 1, [x*(x+1)])
Matrix([[x*(x + 1)]])
>>> _.expand()
Matrix([[x**2 + x]])
"""
return self.applyfunc(lambda x: x.expand(
deep, modulus, power_base, power_exp, mul, log, multinomial, basic,
**hints))
@property
def H(self):
"""Return Hermite conjugate.
Examples
========
>>> from sympy import Matrix, I
>>> m = Matrix((0, 1 + I, 2, 3))
>>> m
Matrix([
[ 0],
[1 + I],
[ 2],
[ 3]])
>>> m.H
Matrix([[0, 1 - I, 2, 3]])
See Also
========
conjugate: By-element conjugation
sympy.matrices.matrices.MatrixBase.D: Dirac conjugation
"""
return self.T.C
def permute(self, perm, orientation='rows', direction='forward'):
r"""Permute the rows or columns of a matrix by the given list of
swaps.
Parameters
==========
perm : Permutation, list, or list of lists
A representation for the permutation.
If it is ``Permutation``, it is used directly with some
resizing with respect to the matrix size.
If it is specified as list of lists,
(e.g., ``[[0, 1], [0, 2]]``), then the permutation is formed
from applying the product of cycles. The direction how the
cyclic product is applied is described in below.
If it is specified as a list, the list should represent
an array form of a permutation. (e.g., ``[1, 2, 0]``) which
would would form the swapping function
`0 \mapsto 1, 1 \mapsto 2, 2\mapsto 0`.
orientation : 'rows', 'cols'
A flag to control whether to permute the rows or the columns
direction : 'forward', 'backward'
A flag to control whether to apply the permutations from
the start of the list first, or from the back of the list
first.
For example, if the permutation specification is
``[[0, 1], [0, 2]]``,
If the flag is set to ``'forward'``, the cycle would be
formed as `0 \mapsto 2, 2 \mapsto 1, 1 \mapsto 0`.
If the flag is set to ``'backward'``, the cycle would be
formed as `0 \mapsto 1, 1 \mapsto 2, 2 \mapsto 0`.
If the argument ``perm`` is not in a form of list of lists,
this flag takes no effect.
Examples
========
>>> from sympy.matrices import eye
>>> M = eye(3)
>>> M.permute([[0, 1], [0, 2]], orientation='rows', direction='forward')
Matrix([
[0, 0, 1],
[1, 0, 0],
[0, 1, 0]])
>>> from sympy.matrices import eye
>>> M = eye(3)
>>> M.permute([[0, 1], [0, 2]], orientation='rows', direction='backward')
Matrix([
[0, 1, 0],
[0, 0, 1],
[1, 0, 0]])
Notes
=====
If a bijective function
`\sigma : \mathbb{N}_0 \rightarrow \mathbb{N}_0` denotes the
permutation.
If the matrix `A` is the matrix to permute, represented as
a horizontal or a vertical stack of vectors:
.. math::
A =
\begin{bmatrix}
a_0 \\ a_1 \\ \vdots \\ a_{n-1}
\end{bmatrix} =
\begin{bmatrix}
\alpha_0 & \alpha_1 & \cdots & \alpha_{n-1}
\end{bmatrix}
If the matrix `B` is the result, the permutation of matrix rows
is defined as:
.. math::
B := \begin{bmatrix}
a_{\sigma(0)} \\ a_{\sigma(1)} \\ \vdots \\ a_{\sigma(n-1)}
\end{bmatrix}
And the permutation of matrix columns is defined as:
.. math::
B := \begin{bmatrix}
\alpha_{\sigma(0)} & \alpha_{\sigma(1)} &
\cdots & \alpha_{\sigma(n-1)}
\end{bmatrix}
"""
from sympy.combinatorics import Permutation
# allow british variants and `columns`
if direction == 'forwards':
direction = 'forward'
if direction == 'backwards':
direction = 'backward'
if orientation == 'columns':
orientation = 'cols'
if direction not in ('forward', 'backward'):
raise TypeError("direction='{}' is an invalid kwarg. "
"Try 'forward' or 'backward'".format(direction))
if orientation not in ('rows', 'cols'):
raise TypeError("orientation='{}' is an invalid kwarg. "
"Try 'rows' or 'cols'".format(orientation))
if not isinstance(perm, (Permutation, Iterable)):
raise ValueError(
"{} must be a list, a list of lists, "
"or a SymPy permutation object.".format(perm))
# ensure all swaps are in range
max_index = self.rows if orientation == 'rows' else self.cols
if not all(0 <= t <= max_index for t in flatten(list(perm))):
raise IndexError("`swap` indices out of range.")
if perm and not isinstance(perm, Permutation) and \
isinstance(perm[0], Iterable):
if direction == 'forward':
perm = list(reversed(perm))
perm = Permutation(perm, size=max_index+1)
else:
perm = Permutation(perm, size=max_index+1)
if orientation == 'rows':
return self._eval_permute_rows(perm)
if orientation == 'cols':
return self._eval_permute_cols(perm)
def permute_cols(self, swaps, direction='forward'):
"""Alias for
``self.permute(swaps, orientation='cols', direction=direction)``
See Also
========
permute
"""
return self.permute(swaps, orientation='cols', direction=direction)
def permute_rows(self, swaps, direction='forward'):
"""Alias for
``self.permute(swaps, orientation='rows', direction=direction)``
See Also
========
permute
"""
return self.permute(swaps, orientation='rows', direction=direction)
def refine(self, assumptions=True):
"""Apply refine to each element of the matrix.
Examples
========
>>> from sympy import Symbol, Matrix, Abs, sqrt, Q
>>> x = Symbol('x')
>>> Matrix([[Abs(x)**2, sqrt(x**2)],[sqrt(x**2), Abs(x)**2]])
Matrix([
[ Abs(x)**2, sqrt(x**2)],
[sqrt(x**2), Abs(x)**2]])
>>> _.refine(Q.real(x))
Matrix([
[ x**2, Abs(x)],
[Abs(x), x**2]])
"""
return self.applyfunc(lambda x: refine(x, assumptions))
def replace(self, F, G, map=False, simultaneous=True, exact=None):
"""Replaces Function F in Matrix entries with Function G.
Examples
========
>>> from sympy import symbols, Function, Matrix
>>> F, G = symbols('F, G', cls=Function)
>>> M = Matrix(2, 2, lambda i, j: F(i+j)) ; M
Matrix([
[F(0), F(1)],
[F(1), F(2)]])
>>> N = M.replace(F,G)
>>> N
Matrix([
[G(0), G(1)],
[G(1), G(2)]])
"""
return self.applyfunc(
lambda x: x.replace(F, G, map=map, simultaneous=simultaneous, exact=exact))
def rot90(self, k=1):
"""Rotates Matrix by 90 degrees
Parameters
==========
k : int
Specifies how many times the matrix is rotated by 90 degrees
(clockwise when positive, counter-clockwise when negative).
Examples
========
>>> from sympy import Matrix, symbols
>>> A = Matrix(2, 2, symbols('a:d'))
>>> A
Matrix([
[a, b],
[c, d]])
Rotating the matrix clockwise one time:
>>> A.rot90(1)
Matrix([
[c, a],
[d, b]])
Rotating the matrix anticlockwise two times:
>>> A.rot90(-2)
Matrix([
[d, c],
[b, a]])
"""
mod = k%4
if mod == 0:
return self
if mod == 1:
return self[::-1, ::].T
if mod == 2:
return self[::-1, ::-1]
if mod == 3:
return self[::, ::-1].T
def simplify(self, **kwargs):
"""Apply simplify to each element of the matrix.
Examples
========
>>> from sympy.abc import x, y
>>> from sympy import sin, cos
>>> from sympy.matrices import SparseMatrix
>>> SparseMatrix(1, 1, [x*sin(y)**2 + x*cos(y)**2])
Matrix([[x*sin(y)**2 + x*cos(y)**2]])
>>> _.simplify()
Matrix([[x]])
"""
return self.applyfunc(lambda x: x.simplify(**kwargs))
def subs(self, *args, **kwargs): # should mirror core.basic.subs
"""Return a new matrix with subs applied to each entry.
Examples
========
>>> from sympy.abc import x, y
>>> from sympy.matrices import SparseMatrix, Matrix
>>> SparseMatrix(1, 1, [x])
Matrix([[x]])
>>> _.subs(x, y)
Matrix([[y]])
>>> Matrix(_).subs(y, x)
Matrix([[x]])
"""
if len(args) == 1 and not isinstance(args[0], (dict, set)) and iter(args[0]) and not is_sequence(args[0]):
args = (list(args[0]),)
return self.applyfunc(lambda x: x.subs(*args, **kwargs))
def trace(self):
"""
Returns the trace of a square matrix i.e. the sum of the
diagonal elements.
Examples
========
>>> from sympy import Matrix
>>> A = Matrix(2, 2, [1, 2, 3, 4])
>>> A.trace()
5
"""
if self.rows != self.cols:
raise NonSquareMatrixError()
return self._eval_trace()
def transpose(self):
"""
Returns the transpose of the matrix.
Examples
========
>>> from sympy import Matrix
>>> A = Matrix(2, 2, [1, 2, 3, 4])
>>> A.transpose()
Matrix([
[1, 3],
[2, 4]])
>>> from sympy import Matrix, I
>>> m=Matrix(((1, 2+I), (3, 4)))
>>> m
Matrix([
[1, 2 + I],
[3, 4]])
>>> m.transpose()
Matrix([
[ 1, 3],
[2 + I, 4]])
>>> m.T == m.transpose()
True
See Also
========
conjugate: By-element conjugation
"""
return self._eval_transpose()
@property
def T(self):
'''Matrix transposition'''
return self.transpose()
@property
def C(self):
'''By-element conjugation'''
return self.conjugate()
def n(self, *args, **kwargs):
"""Apply evalf() to each element of self."""
return self.evalf(*args, **kwargs)
def xreplace(self, rule): # should mirror core.basic.xreplace
"""Return a new matrix with xreplace applied to each entry.
Examples
========
>>> from sympy.abc import x, y
>>> from sympy.matrices import SparseMatrix, Matrix
>>> SparseMatrix(1, 1, [x])
Matrix([[x]])
>>> _.xreplace({x: y})
Matrix([[y]])
>>> Matrix(_).xreplace({y: x})
Matrix([[x]])
"""
return self.applyfunc(lambda x: x.xreplace(rule))
def _eval_simplify(self, **kwargs):
# XXX: We can't use self.simplify here as mutable subclasses will
# override simplify and have it return None
return MatrixOperations.simplify(self, **kwargs)
def _eval_trigsimp(self, **opts):
from sympy.simplify import trigsimp
return self.applyfunc(lambda x: trigsimp(x, **opts))
def upper_triangular(self, k=0):
"""returns the elements on and above the kth diagonal of a matrix.
If k is not specified then simply returns upper-triangular portion
of a matrix
Examples
========
>>> from sympy import ones
>>> A = ones(4)
>>> A.upper_triangular()
Matrix([
[1, 1, 1, 1],
[0, 1, 1, 1],
[0, 0, 1, 1],
[0, 0, 0, 1]])
>>> A.upper_triangular(2)
Matrix([
[0, 0, 1, 1],
[0, 0, 0, 1],
[0, 0, 0, 0],
[0, 0, 0, 0]])
>>> A.upper_triangular(-1)
Matrix([
[1, 1, 1, 1],
[1, 1, 1, 1],
[0, 1, 1, 1],
[0, 0, 1, 1]])
"""
def entry(i, j):
return self[i, j] if i + k <= j else self.zero
return self._new(self.rows, self.cols, entry)
def lower_triangular(self, k=0):
"""returns the elements on and below the kth diagonal of a matrix.
If k is not specified then simply returns lower-triangular portion
of a matrix
Examples
========
>>> from sympy import ones
>>> A = ones(4)
>>> A.lower_triangular()
Matrix([
[1, 0, 0, 0],
[1, 1, 0, 0],
[1, 1, 1, 0],
[1, 1, 1, 1]])
>>> A.lower_triangular(-2)
Matrix([
[0, 0, 0, 0],
[0, 0, 0, 0],
[1, 0, 0, 0],
[1, 1, 0, 0]])
>>> A.lower_triangular(1)
Matrix([
[1, 1, 0, 0],
[1, 1, 1, 0],
[1, 1, 1, 1],
[1, 1, 1, 1]])
"""
def entry(i, j):
return self[i, j] if i + k >= j else self.zero
return self._new(self.rows, self.cols, entry)
class MatrixArithmetic(MatrixRequired):
"""Provides basic matrix arithmetic operations.
Should not be instantiated directly."""
_op_priority = 10.01
def _eval_Abs(self):
return self._new(self.rows, self.cols, lambda i, j: Abs(self[i, j]))
def _eval_add(self, other):
return self._new(self.rows, self.cols,
lambda i, j: self[i, j] + other[i, j])
def _eval_matrix_mul(self, other):
def entry(i, j):
vec = [self[i,k]*other[k,j] for k in range(self.cols)]
try:
return Add(*vec)
except (TypeError, SympifyError):
# Some matrices don't work with `sum` or `Add`
# They don't work with `sum` because `sum` tries to add `0`
# Fall back to a safe way to multiply if the `Add` fails.
return reduce(lambda a, b: a + b, vec)
return self._new(self.rows, other.cols, entry)
def _eval_matrix_mul_elementwise(self, other):
return self._new(self.rows, self.cols, lambda i, j: self[i,j]*other[i,j])
def _eval_matrix_rmul(self, other):
def entry(i, j):
return sum(other[i,k]*self[k,j] for k in range(other.cols))
return self._new(other.rows, self.cols, entry)
def _eval_pow_by_recursion(self, num):
if num == 1:
return self
if num % 2 == 1:
a, b = self, self._eval_pow_by_recursion(num - 1)
else:
a = b = self._eval_pow_by_recursion(num // 2)
return a.multiply(b)
def _eval_pow_by_cayley(self, exp):
from sympy.discrete.recurrences import linrec_coeffs
row = self.shape[0]
p = self.charpoly()
coeffs = (-p).all_coeffs()[1:]
coeffs = linrec_coeffs(coeffs, exp)
new_mat = self.eye(row)
ans = self.zeros(row)
for i in range(row):
ans += coeffs[i]*new_mat
new_mat *= self
return ans
def _eval_pow_by_recursion_dotprodsimp(self, num, prevsimp=None):
if prevsimp is None:
prevsimp = [True]*len(self)
if num == 1:
return self
if num % 2 == 1:
a, b = self, self._eval_pow_by_recursion_dotprodsimp(num - 1,
prevsimp=prevsimp)
else:
a = b = self._eval_pow_by_recursion_dotprodsimp(num // 2,
prevsimp=prevsimp)
m = a.multiply(b, dotprodsimp=False)
lenm = len(m)
elems = [None]*lenm
for i in range(lenm):
if prevsimp[i]:
elems[i], prevsimp[i] = _dotprodsimp(m[i], withsimp=True)
else:
elems[i] = m[i]
return m._new(m.rows, m.cols, elems)
def _eval_scalar_mul(self, other):
return self._new(self.rows, self.cols, lambda i, j: self[i,j]*other)
def _eval_scalar_rmul(self, other):
return self._new(self.rows, self.cols, lambda i, j: other*self[i,j])
def _eval_Mod(self, other):
from sympy import Mod
return self._new(self.rows, self.cols, lambda i, j: Mod(self[i, j], other))
# python arithmetic functions
def __abs__(self):
"""Returns a new matrix with entry-wise absolute values."""
return self._eval_Abs()
@call_highest_priority('__radd__')
def __add__(self, other):
"""Return self + other, raising ShapeError if shapes don't match."""
if isinstance(other, NDimArray): # Matrix and array addition is currently not implemented
return NotImplemented
other = _matrixify(other)
# matrix-like objects can have shapes. This is
# our first sanity check.
if hasattr(other, 'shape'):
if self.shape != other.shape:
raise ShapeError("Matrix size mismatch: %s + %s" % (
self.shape, other.shape))
# honest sympy matrices defer to their class's routine
if getattr(other, 'is_Matrix', False):
# call the highest-priority class's _eval_add
a, b = self, other
if a.__class__ != classof(a, b):
b, a = a, b
return a._eval_add(b)
# Matrix-like objects can be passed to CommonMatrix routines directly.
if getattr(other, 'is_MatrixLike', False):
return MatrixArithmetic._eval_add(self, other)
raise TypeError('cannot add %s and %s' % (type(self), type(other)))
@call_highest_priority('__rtruediv__')
def __truediv__(self, other):
return self * (self.one / other)
@call_highest_priority('__rmatmul__')
def __matmul__(self, other):
other = _matrixify(other)
if not getattr(other, 'is_Matrix', False) and not getattr(other, 'is_MatrixLike', False):
return NotImplemented
return self.__mul__(other)
def __mod__(self, other):
return self.applyfunc(lambda x: x % other)
@call_highest_priority('__rmul__')
def __mul__(self, other):
"""Return self*other where other is either a scalar or a matrix
of compatible dimensions.
Examples
========
>>> from sympy.matrices import Matrix
>>> A = Matrix([[1, 2, 3], [4, 5, 6]])
>>> 2*A == A*2 == Matrix([[2, 4, 6], [8, 10, 12]])
True
>>> B = Matrix([[1, 2, 3], [4, 5, 6], [7, 8, 9]])
>>> A*B
Matrix([
[30, 36, 42],
[66, 81, 96]])
>>> B*A
Traceback (most recent call last):
...
ShapeError: Matrices size mismatch.
>>>
See Also
========
matrix_multiply_elementwise
"""
return self.multiply(other)
def multiply(self, other, dotprodsimp=None):
"""Same as __mul__() but with optional simplification.
Parameters
==========
dotprodsimp : bool, optional
Specifies whether intermediate term algebraic simplification is used
during matrix multiplications to control expression blowup and thus
speed up calculation. Default is off.
"""
isimpbool = _get_intermediate_simp_bool(False, dotprodsimp)
other = _matrixify(other)
# matrix-like objects can have shapes. This is
# our first sanity check. Double check other is not explicitly not a Matrix.
if (hasattr(other, 'shape') and len(other.shape) == 2 and
(getattr(other, 'is_Matrix', True) or
getattr(other, 'is_MatrixLike', True))):
if self.shape[1] != other.shape[0]:
raise ShapeError("Matrix size mismatch: %s * %s." % (
self.shape, other.shape))
# honest sympy matrices defer to their class's routine
if getattr(other, 'is_Matrix', False):
m = self._eval_matrix_mul(other)
if isimpbool:
return m._new(m.rows, m.cols, [_dotprodsimp(e) for e in m])
return m
# Matrix-like objects can be passed to CommonMatrix routines directly.
if getattr(other, 'is_MatrixLike', False):
return MatrixArithmetic._eval_matrix_mul(self, other)
# if 'other' is not iterable then scalar multiplication.
if not isinstance(other, Iterable):
try:
return self._eval_scalar_mul(other)
except TypeError:
pass
return NotImplemented
def multiply_elementwise(self, other):
"""Return the Hadamard product (elementwise product) of A and B
Examples
========
>>> from sympy.matrices import Matrix
>>> A = Matrix([[0, 1, 2], [3, 4, 5]])
>>> B = Matrix([[1, 10, 100], [100, 10, 1]])
>>> A.multiply_elementwise(B)
Matrix([
[ 0, 10, 200],
[300, 40, 5]])
See Also
========
sympy.matrices.matrices.MatrixBase.cross
sympy.matrices.matrices.MatrixBase.dot
multiply
"""
if self.shape != other.shape:
raise ShapeError("Matrix shapes must agree {} != {}".format(self.shape, other.shape))
return self._eval_matrix_mul_elementwise(other)
def __neg__(self):
return self._eval_scalar_mul(-1)
@call_highest_priority('__rpow__')
def __pow__(self, exp):
"""Return self**exp a scalar or symbol."""
return self.pow(exp)
def pow(self, exp, method=None):
r"""Return self**exp a scalar or symbol.
Parameters
==========
method : multiply, mulsimp, jordan, cayley
If multiply then it returns exponentiation using recursion.
If jordan then Jordan form exponentiation will be used.
If cayley then the exponentiation is done using Cayley-Hamilton
theorem.
If mulsimp then the exponentiation is done using recursion
with dotprodsimp. This specifies whether intermediate term
algebraic simplification is used during naive matrix power to
control expression blowup and thus speed up calculation.
If None, then it heuristically decides which method to use.
"""
if method is not None and method not in ['multiply', 'mulsimp', 'jordan', 'cayley']:
raise TypeError('No such method')
if self.rows != self.cols:
raise NonSquareMatrixError()
a = self
jordan_pow = getattr(a, '_matrix_pow_by_jordan_blocks', None)
exp = sympify(exp)
if exp.is_zero:
return a._new(a.rows, a.cols, lambda i, j: int(i == j))
if exp == 1:
return a
diagonal = getattr(a, 'is_diagonal', None)
if diagonal is not None and diagonal():
return a._new(a.rows, a.cols, lambda i, j: a[i,j]**exp if i == j else 0)
if exp.is_Number and exp % 1 == 0:
if a.rows == 1:
return a._new([[a[0]**exp]])
if exp < 0:
exp = -exp
a = a.inv()
# When certain conditions are met,
# Jordan block algorithm is faster than
# computation by recursion.
if method == 'jordan':
try:
return jordan_pow(exp)
except MatrixError:
if method == 'jordan':
raise
elif method == 'cayley':
if not exp.is_Number or exp % 1 != 0:
raise ValueError("cayley method is only valid for integer powers")
return a._eval_pow_by_cayley(exp)
elif method == "mulsimp":
if not exp.is_Number or exp % 1 != 0:
raise ValueError("mulsimp method is only valid for integer powers")
return a._eval_pow_by_recursion_dotprodsimp(exp)
elif method == "multiply":
if not exp.is_Number or exp % 1 != 0:
raise ValueError("multiply method is only valid for integer powers")
return a._eval_pow_by_recursion(exp)
elif method is None and exp.is_Number and exp % 1 == 0:
# Decide heuristically which method to apply
if a.rows == 2 and exp > 100000:
return jordan_pow(exp)
elif _get_intermediate_simp_bool(True, None):
return a._eval_pow_by_recursion_dotprodsimp(exp)
elif exp > 10000:
return a._eval_pow_by_cayley(exp)
else:
return a._eval_pow_by_recursion(exp)
if jordan_pow:
try:
return jordan_pow(exp)
except NonInvertibleMatrixError:
# Raised by jordan_pow on zero determinant matrix unless exp is
# definitely known to be a non-negative integer.
# Here we raise if n is definitely not a non-negative integer
# but otherwise we can leave this as an unevaluated MatPow.
if exp.is_integer is False or exp.is_nonnegative is False:
raise
from sympy.matrices.expressions import MatPow
return MatPow(a, exp)
@call_highest_priority('__add__')
def __radd__(self, other):
return self + other
@call_highest_priority('__matmul__')
def __rmatmul__(self, other):
other = _matrixify(other)
if not getattr(other, 'is_Matrix', False) and not getattr(other, 'is_MatrixLike', False):
return NotImplemented
return self.__rmul__(other)
@call_highest_priority('__mul__')
def __rmul__(self, other):
return self.rmultiply(other)
def rmultiply(self, other, dotprodsimp=None):
"""Same as __rmul__() but with optional simplification.
Parameters
==========
dotprodsimp : bool, optional
Specifies whether intermediate term algebraic simplification is used
during matrix multiplications to control expression blowup and thus
speed up calculation. Default is off.
"""
isimpbool = _get_intermediate_simp_bool(False, dotprodsimp)
other = _matrixify(other)
# matrix-like objects can have shapes. This is
# our first sanity check. Double check other is not explicitly not a Matrix.
if (hasattr(other, 'shape') and len(other.shape) == 2 and
(getattr(other, 'is_Matrix', True) or
getattr(other, 'is_MatrixLike', True))):
if self.shape[0] != other.shape[1]:
raise ShapeError("Matrix size mismatch.")
# honest sympy matrices defer to their class's routine
if getattr(other, 'is_Matrix', False):
m = self._eval_matrix_rmul(other)
if isimpbool:
return m._new(m.rows, m.cols, [_dotprodsimp(e) for e in m])
return m
# Matrix-like objects can be passed to CommonMatrix routines directly.
if getattr(other, 'is_MatrixLike', False):
return MatrixArithmetic._eval_matrix_rmul(self, other)
# if 'other' is not iterable then scalar multiplication.
if not isinstance(other, Iterable):
try:
return self._eval_scalar_rmul(other)
except TypeError:
pass
return NotImplemented
@call_highest_priority('__sub__')
def __rsub__(self, a):
return (-self) + a
@call_highest_priority('__rsub__')
def __sub__(self, a):
return self + (-a)
class MatrixCommon(MatrixArithmetic, MatrixOperations, MatrixProperties,
MatrixSpecial, MatrixShaping):
"""All common matrix operations including basic arithmetic, shaping,
and special matrices like `zeros`, and `eye`."""
_diff_wrt = True # type: bool
class _MinimalMatrix:
"""Class providing the minimum functionality
for a matrix-like object and implementing every method
required for a `MatrixRequired`. This class does not have everything
needed to become a full-fledged SymPy object, but it will satisfy the
requirements of anything inheriting from `MatrixRequired`. If you wish
to make a specialized matrix type, make sure to implement these
methods and properties with the exception of `__init__` and `__repr__`
which are included for convenience."""
is_MatrixLike = True
_sympify = staticmethod(sympify)
_class_priority = 3
zero = S.Zero
one = S.One
is_Matrix = True
is_MatrixExpr = False
@classmethod
def _new(cls, *args, **kwargs):
return cls(*args, **kwargs)
def __init__(self, rows, cols=None, mat=None, copy=False):
if isfunction(mat):
# if we passed in a function, use that to populate the indices
mat = list(mat(i, j) for i in range(rows) for j in range(cols))
if cols is None and mat is None:
mat = rows
rows, cols = getattr(mat, 'shape', (rows, cols))
try:
# if we passed in a list of lists, flatten it and set the size
if cols is None and mat is None:
mat = rows
cols = len(mat[0])
rows = len(mat)
mat = [x for l in mat for x in l]
except (IndexError, TypeError):
pass
self.mat = tuple(self._sympify(x) for x in mat)
self.rows, self.cols = rows, cols
if self.rows is None or self.cols is None:
raise NotImplementedError("Cannot initialize matrix with given parameters")
def __getitem__(self, key):
def _normalize_slices(row_slice, col_slice):
"""Ensure that row_slice and col_slice don't have
`None` in their arguments. Any integers are converted
to slices of length 1"""
if not isinstance(row_slice, slice):
row_slice = slice(row_slice, row_slice + 1, None)
row_slice = slice(*row_slice.indices(self.rows))
if not isinstance(col_slice, slice):
col_slice = slice(col_slice, col_slice + 1, None)
col_slice = slice(*col_slice.indices(self.cols))
return (row_slice, col_slice)
def _coord_to_index(i, j):
"""Return the index in _mat corresponding
to the (i,j) position in the matrix. """
return i * self.cols + j
if isinstance(key, tuple):
i, j = key
if isinstance(i, slice) or isinstance(j, slice):
# if the coordinates are not slices, make them so
# and expand the slices so they don't contain `None`
i, j = _normalize_slices(i, j)
rowsList, colsList = list(range(self.rows))[i], \
list(range(self.cols))[j]
indices = (i * self.cols + j for i in rowsList for j in
colsList)
return self._new(len(rowsList), len(colsList),
list(self.mat[i] for i in indices))
# if the key is a tuple of ints, change
# it to an array index
key = _coord_to_index(i, j)
return self.mat[key]
def __eq__(self, other):
try:
classof(self, other)
except TypeError:
return False
return (
self.shape == other.shape and list(self) == list(other))
def __len__(self):
return self.rows*self.cols
def __repr__(self):
return "_MinimalMatrix({}, {}, {})".format(self.rows, self.cols,
self.mat)
@property
def shape(self):
return (self.rows, self.cols)
class _CastableMatrix: # this is needed here ONLY FOR TESTS.
def as_mutable(self):
return self
def as_immutable(self):
return self
class _MatrixWrapper:
"""Wrapper class providing the minimum functionality for a matrix-like
object: .rows, .cols, .shape, indexability, and iterability. CommonMatrix
math operations should work on matrix-like objects. This one is intended for
matrix-like objects which use the same indexing format as SymPy with respect
to returning matrix elements instead of rows for non-tuple indexes.
"""
is_Matrix = False # needs to be here because of __getattr__
is_MatrixLike = True
def __init__(self, mat, shape):
self.mat = mat
self.shape = shape
self.rows, self.cols = shape
def __getitem__(self, key):
if isinstance(key, tuple):
return sympify(self.mat.__getitem__(key))
return sympify(self.mat.__getitem__((key // self.rows, key % self.cols)))
def __iter__(self): # supports numpy.matrix and numpy.array
mat = self.mat
cols = self.cols
return iter(sympify(mat[r, c]) for r in range(self.rows) for c in range(cols))
class MatrixKind(Kind):
"""
Kind for all matrices in SymPy.
Basic class for this kind is ``MatrixBase`` and ``MatrixExpr``,
but any expression representing the matrix can have this.
Parameters
==========
element_kind : Kind
Kind of the element. Default is :obj:NumberKind `<sympy.core.kind.NumberKind>`,
which means that the matrix contains only numbers.
Examples
========
Any instance of matrix class has ``MatrixKind``.
>>> from sympy import MatrixSymbol
>>> A = MatrixSymbol('A', 2,2)
>>> A.kind
MatrixKind(NumberKind)
Although expression representing a matrix may be not instance of
matrix class, it will have ``MatrixKind`` as well.
>>> from sympy import Integral
>>> from sympy.matrices.expressions import MatrixExpr
>>> from sympy.abc import x
>>> intM = Integral(A, x)
>>> isinstance(intM, MatrixExpr)
False
>>> intM.kind
MatrixKind(NumberKind)
Use ``isinstance()`` to check for ``MatrixKind` without specifying
the element kind. Use ``is`` with specifying the element kind.
>>> from sympy import Matrix
>>> from sympy.matrices import MatrixKind
>>> from sympy.core.kind import NumberKind
>>> M = Matrix([1, 2])
>>> isinstance(M.kind, MatrixKind)
True
>>> M.kind is MatrixKind(NumberKind)
True
See Also
========
shape : Function to return the shape of objects with ``MatrixKind``.
"""
def __new__(cls, element_kind=NumberKind):
obj = super().__new__(cls, element_kind)
obj.element_kind = element_kind
return obj
def __repr__(self):
return "MatrixKind(%s)" % self.element_kind
def _matrixify(mat):
"""If `mat` is a Matrix or is matrix-like,
return a Matrix or MatrixWrapper object. Otherwise
`mat` is passed through without modification."""
if getattr(mat, 'is_Matrix', False) or getattr(mat, 'is_MatrixLike', False):
return mat
if not(getattr(mat, 'is_Matrix', True) or getattr(mat, 'is_MatrixLike', True)):
return mat
shape = None
if hasattr(mat, 'shape'): # numpy, scipy.sparse
if len(mat.shape) == 2:
shape = mat.shape
elif hasattr(mat, 'rows') and hasattr(mat, 'cols'): # mpmath
shape = (mat.rows, mat.cols)
if shape:
return _MatrixWrapper(mat, shape)
return mat
def a2idx(j, n=None):
"""Return integer after making positive and validating against n."""
if type(j) is not int:
jindex = getattr(j, '__index__', None)
if jindex is not None:
j = jindex()
else:
raise IndexError("Invalid index a[%r]" % (j,))
if n is not None:
if j < 0:
j += n
if not (j >= 0 and j < n):
raise IndexError("Index out of range: a[%s]" % (j,))
return int(j)
def classof(A, B):
"""
Get the type of the result when combining matrices of different types.
Currently the strategy is that immutability is contagious.
Examples
========
>>> from sympy import Matrix, ImmutableMatrix
>>> from sympy.matrices.common import classof
>>> M = Matrix([[1, 2], [3, 4]]) # a Mutable Matrix
>>> IM = ImmutableMatrix([[1, 2], [3, 4]])
>>> classof(M, IM)
<class 'sympy.matrices.immutable.ImmutableDenseMatrix'>
"""
priority_A = getattr(A, '_class_priority', None)
priority_B = getattr(B, '_class_priority', None)
if None not in (priority_A, priority_B):
if A._class_priority > B._class_priority:
return A.__class__
else:
return B.__class__
try:
import numpy
except ImportError:
pass
else:
if isinstance(A, numpy.ndarray):
return B.__class__
if isinstance(B, numpy.ndarray):
return A.__class__
raise TypeError("Incompatible classes %s, %s" % (A.__class__, B.__class__))
|
52cf20c156db4bfae718fcc8038b73a177c72ca1a93d37c82e52604fe5471755 | import random
from sympy.core.basic import Basic
from sympy.core.compatibility import is_sequence
from sympy.core.symbol import Symbol
from sympy.core.sympify import sympify
from sympy.functions.elementary.trigonometric import cos, sin
from sympy.simplify.simplify import simplify as _simplify
from sympy.utilities.decorator import doctest_depends_on
from sympy.utilities.exceptions import SymPyDeprecationWarning
from .common import ShapeError
from .decompositions import _cholesky, _LDLdecomposition
from .matrices import MatrixBase
from .repmatrix import MutableRepMatrix, RepMatrix
from .solvers import _lower_triangular_solve, _upper_triangular_solve
def _iszero(x):
"""Returns True if x is zero."""
return x.is_zero
class DenseMatrix(RepMatrix):
"""Matrix implementation based on DomainMatrix as the internal representation"""
#
# DenseMatrix is a superclass for both MutableDenseMatrix and
# ImmutableDenseMatrix. Methods shared by both classes but not for the
# Sparse classes should be implemented here.
#
is_MatrixExpr = False # type: bool
_op_priority = 10.01
_class_priority = 4
@property
def _mat(self):
SymPyDeprecationWarning(
feature="The private _mat attribute of Matrix",
useinstead="the .flat() method",
issue=21715,
deprecated_since_version="1.9").warn()
return self.flat()
def _eval_inverse(self, **kwargs):
return self.inv(method=kwargs.get('method', 'GE'),
iszerofunc=kwargs.get('iszerofunc', _iszero),
try_block_diag=kwargs.get('try_block_diag', False))
def as_immutable(self):
"""Returns an Immutable version of this Matrix
"""
from .immutable import ImmutableDenseMatrix as cls
return cls._fromrep(self._rep.copy())
def as_mutable(self):
"""Returns a mutable version of this matrix
Examples
========
>>> from sympy import ImmutableMatrix
>>> X = ImmutableMatrix([[1, 2], [3, 4]])
>>> Y = X.as_mutable()
>>> Y[1, 1] = 5 # Can set values in Y
>>> Y
Matrix([
[1, 2],
[3, 5]])
"""
return Matrix(self)
def cholesky(self, hermitian=True):
return _cholesky(self, hermitian=hermitian)
def LDLdecomposition(self, hermitian=True):
return _LDLdecomposition(self, hermitian=hermitian)
def lower_triangular_solve(self, rhs):
return _lower_triangular_solve(self, rhs)
def upper_triangular_solve(self, rhs):
return _upper_triangular_solve(self, rhs)
cholesky.__doc__ = _cholesky.__doc__
LDLdecomposition.__doc__ = _LDLdecomposition.__doc__
lower_triangular_solve.__doc__ = _lower_triangular_solve.__doc__
upper_triangular_solve.__doc__ = _upper_triangular_solve.__doc__
def _force_mutable(x):
"""Return a matrix as a Matrix, otherwise return x."""
if getattr(x, 'is_Matrix', False):
return x.as_mutable()
elif isinstance(x, Basic):
return x
elif hasattr(x, '__array__'):
a = x.__array__()
if len(a.shape) == 0:
return sympify(a)
return Matrix(x)
return x
class MutableDenseMatrix(DenseMatrix, MutableRepMatrix):
def simplify(self, **kwargs):
"""Applies simplify to the elements of a matrix in place.
This is a shortcut for M.applyfunc(lambda x: simplify(x, ratio, measure))
See Also
========
sympy.simplify.simplify.simplify
"""
for (i, j), element in self.todok().items():
self[i, j] = _simplify(element, **kwargs)
MutableMatrix = Matrix = MutableDenseMatrix
###########
# Numpy Utility Functions:
# list2numpy, matrix2numpy, symmarray, rot_axis[123]
###########
def list2numpy(l, dtype=object): # pragma: no cover
"""Converts python list of SymPy expressions to a NumPy array.
See Also
========
matrix2numpy
"""
from numpy import empty
a = empty(len(l), dtype)
for i, s in enumerate(l):
a[i] = s
return a
def matrix2numpy(m, dtype=object): # pragma: no cover
"""Converts SymPy's matrix to a NumPy array.
See Also
========
list2numpy
"""
from numpy import empty
a = empty(m.shape, dtype)
for i in range(m.rows):
for j in range(m.cols):
a[i, j] = m[i, j]
return a
def rot_axis3(theta):
"""Returns a rotation matrix for a rotation of theta (in radians) about
the 3-axis.
Examples
========
>>> from sympy import pi
>>> from sympy.matrices import rot_axis3
A rotation of pi/3 (60 degrees):
>>> theta = pi/3
>>> rot_axis3(theta)
Matrix([
[ 1/2, sqrt(3)/2, 0],
[-sqrt(3)/2, 1/2, 0],
[ 0, 0, 1]])
If we rotate by pi/2 (90 degrees):
>>> rot_axis3(pi/2)
Matrix([
[ 0, 1, 0],
[-1, 0, 0],
[ 0, 0, 1]])
See Also
========
rot_axis1: Returns a rotation matrix for a rotation of theta (in radians)
about the 1-axis
rot_axis2: Returns a rotation matrix for a rotation of theta (in radians)
about the 2-axis
"""
ct = cos(theta)
st = sin(theta)
lil = ((ct, st, 0),
(-st, ct, 0),
(0, 0, 1))
return Matrix(lil)
def rot_axis2(theta):
"""Returns a rotation matrix for a rotation of theta (in radians) about
the 2-axis.
Examples
========
>>> from sympy import pi
>>> from sympy.matrices import rot_axis2
A rotation of pi/3 (60 degrees):
>>> theta = pi/3
>>> rot_axis2(theta)
Matrix([
[ 1/2, 0, -sqrt(3)/2],
[ 0, 1, 0],
[sqrt(3)/2, 0, 1/2]])
If we rotate by pi/2 (90 degrees):
>>> rot_axis2(pi/2)
Matrix([
[0, 0, -1],
[0, 1, 0],
[1, 0, 0]])
See Also
========
rot_axis1: Returns a rotation matrix for a rotation of theta (in radians)
about the 1-axis
rot_axis3: Returns a rotation matrix for a rotation of theta (in radians)
about the 3-axis
"""
ct = cos(theta)
st = sin(theta)
lil = ((ct, 0, -st),
(0, 1, 0),
(st, 0, ct))
return Matrix(lil)
def rot_axis1(theta):
"""Returns a rotation matrix for a rotation of theta (in radians) about
the 1-axis.
Examples
========
>>> from sympy import pi
>>> from sympy.matrices import rot_axis1
A rotation of pi/3 (60 degrees):
>>> theta = pi/3
>>> rot_axis1(theta)
Matrix([
[1, 0, 0],
[0, 1/2, sqrt(3)/2],
[0, -sqrt(3)/2, 1/2]])
If we rotate by pi/2 (90 degrees):
>>> rot_axis1(pi/2)
Matrix([
[1, 0, 0],
[0, 0, 1],
[0, -1, 0]])
See Also
========
rot_axis2: Returns a rotation matrix for a rotation of theta (in radians)
about the 2-axis
rot_axis3: Returns a rotation matrix for a rotation of theta (in radians)
about the 3-axis
"""
ct = cos(theta)
st = sin(theta)
lil = ((1, 0, 0),
(0, ct, st),
(0, -st, ct))
return Matrix(lil)
@doctest_depends_on(modules=('numpy',))
def symarray(prefix, shape, **kwargs): # pragma: no cover
r"""Create a numpy ndarray of symbols (as an object array).
The created symbols are named ``prefix_i1_i2_``... You should thus provide a
non-empty prefix if you want your symbols to be unique for different output
arrays, as SymPy symbols with identical names are the same object.
Parameters
----------
prefix : string
A prefix prepended to the name of every symbol.
shape : int or tuple
Shape of the created array. If an int, the array is one-dimensional; for
more than one dimension the shape must be a tuple.
\*\*kwargs : dict
keyword arguments passed on to Symbol
Examples
========
These doctests require numpy.
>>> from sympy import symarray
>>> symarray('', 3)
[_0 _1 _2]
If you want multiple symarrays to contain distinct symbols, you *must*
provide unique prefixes:
>>> a = symarray('', 3)
>>> b = symarray('', 3)
>>> a[0] == b[0]
True
>>> a = symarray('a', 3)
>>> b = symarray('b', 3)
>>> a[0] == b[0]
False
Creating symarrays with a prefix:
>>> symarray('a', 3)
[a_0 a_1 a_2]
For more than one dimension, the shape must be given as a tuple:
>>> symarray('a', (2, 3))
[[a_0_0 a_0_1 a_0_2]
[a_1_0 a_1_1 a_1_2]]
>>> symarray('a', (2, 3, 2))
[[[a_0_0_0 a_0_0_1]
[a_0_1_0 a_0_1_1]
[a_0_2_0 a_0_2_1]]
<BLANKLINE>
[[a_1_0_0 a_1_0_1]
[a_1_1_0 a_1_1_1]
[a_1_2_0 a_1_2_1]]]
For setting assumptions of the underlying Symbols:
>>> [s.is_real for s in symarray('a', 2, real=True)]
[True, True]
"""
from numpy import empty, ndindex
arr = empty(shape, dtype=object)
for index in ndindex(shape):
arr[index] = Symbol('%s_%s' % (prefix, '_'.join(map(str, index))),
**kwargs)
return arr
###############
# Functions
###############
def casoratian(seqs, n, zero=True):
"""Given linear difference operator L of order 'k' and homogeneous
equation Ly = 0 we want to compute kernel of L, which is a set
of 'k' sequences: a(n), b(n), ... z(n).
Solutions of L are linearly independent iff their Casoratian,
denoted as C(a, b, ..., z), do not vanish for n = 0.
Casoratian is defined by k x k determinant::
+ a(n) b(n) . . . z(n) +
| a(n+1) b(n+1) . . . z(n+1) |
| . . . . |
| . . . . |
| . . . . |
+ a(n+k-1) b(n+k-1) . . . z(n+k-1) +
It proves very useful in rsolve_hyper() where it is applied
to a generating set of a recurrence to factor out linearly
dependent solutions and return a basis:
>>> from sympy import Symbol, casoratian, factorial
>>> n = Symbol('n', integer=True)
Exponential and factorial are linearly independent:
>>> casoratian([2**n, factorial(n)], n) != 0
True
"""
seqs = list(map(sympify, seqs))
if not zero:
f = lambda i, j: seqs[j].subs(n, n + i)
else:
f = lambda i, j: seqs[j].subs(n, i)
k = len(seqs)
return Matrix(k, k, f).det()
def eye(*args, **kwargs):
"""Create square identity matrix n x n
See Also
========
diag
zeros
ones
"""
return Matrix.eye(*args, **kwargs)
def diag(*values, strict=True, unpack=False, **kwargs):
"""Returns a matrix with the provided values placed on the
diagonal. If non-square matrices are included, they will
produce a block-diagonal matrix.
Examples
========
This version of diag is a thin wrapper to Matrix.diag that differs
in that it treats all lists like matrices -- even when a single list
is given. If this is not desired, either put a `*` before the list or
set `unpack=True`.
>>> from sympy import diag
>>> diag([1, 2, 3], unpack=True) # = diag(1,2,3) or diag(*[1,2,3])
Matrix([
[1, 0, 0],
[0, 2, 0],
[0, 0, 3]])
>>> diag([1, 2, 3]) # a column vector
Matrix([
[1],
[2],
[3]])
See Also
========
.common.MatrixCommon.eye
.common.MatrixCommon.diagonal - to extract a diagonal
.common.MatrixCommon.diag
.expressions.blockmatrix.BlockMatrix
"""
return Matrix.diag(*values, strict=strict, unpack=unpack, **kwargs)
def GramSchmidt(vlist, orthonormal=False):
"""Apply the Gram-Schmidt process to a set of vectors.
Parameters
==========
vlist : List of Matrix
Vectors to be orthogonalized for.
orthonormal : Bool, optional
If true, return an orthonormal basis.
Returns
=======
vlist : List of Matrix
Orthogonalized vectors
Notes
=====
This routine is mostly duplicate from ``Matrix.orthogonalize``,
except for some difference that this always raises error when
linearly dependent vectors are found, and the keyword ``normalize``
has been named as ``orthonormal`` in this function.
See Also
========
.matrices.MatrixSubspaces.orthogonalize
References
==========
.. [1] https://en.wikipedia.org/wiki/Gram%E2%80%93Schmidt_process
"""
return MutableDenseMatrix.orthogonalize(
*vlist, normalize=orthonormal, rankcheck=True
)
def hessian(f, varlist, constraints=[]):
"""Compute Hessian matrix for a function f wrt parameters in varlist
which may be given as a sequence or a row/column vector. A list of
constraints may optionally be given.
Examples
========
>>> from sympy import Function, hessian, pprint
>>> from sympy.abc import x, y
>>> f = Function('f')(x, y)
>>> g1 = Function('g')(x, y)
>>> g2 = x**2 + 3*y
>>> pprint(hessian(f, (x, y), [g1, g2]))
[ d d ]
[ 0 0 --(g(x, y)) --(g(x, y)) ]
[ dx dy ]
[ ]
[ 0 0 2*x 3 ]
[ ]
[ 2 2 ]
[d d d ]
[--(g(x, y)) 2*x ---(f(x, y)) -----(f(x, y))]
[dx 2 dy dx ]
[ dx ]
[ ]
[ 2 2 ]
[d d d ]
[--(g(x, y)) 3 -----(f(x, y)) ---(f(x, y)) ]
[dy dy dx 2 ]
[ dy ]
References
==========
https://en.wikipedia.org/wiki/Hessian_matrix
See Also
========
sympy.matrices.matrices.MatrixCalculus.jacobian
wronskian
"""
# f is the expression representing a function f, return regular matrix
if isinstance(varlist, MatrixBase):
if 1 not in varlist.shape:
raise ShapeError("`varlist` must be a column or row vector.")
if varlist.cols == 1:
varlist = varlist.T
varlist = varlist.tolist()[0]
if is_sequence(varlist):
n = len(varlist)
if not n:
raise ShapeError("`len(varlist)` must not be zero.")
else:
raise ValueError("Improper variable list in hessian function")
if not getattr(f, 'diff'):
# check differentiability
raise ValueError("Function `f` (%s) is not differentiable" % f)
m = len(constraints)
N = m + n
out = zeros(N)
for k, g in enumerate(constraints):
if not getattr(g, 'diff'):
# check differentiability
raise ValueError("Function `f` (%s) is not differentiable" % f)
for i in range(n):
out[k, i + m] = g.diff(varlist[i])
for i in range(n):
for j in range(i, n):
out[i + m, j + m] = f.diff(varlist[i]).diff(varlist[j])
for i in range(N):
for j in range(i + 1, N):
out[j, i] = out[i, j]
return out
def jordan_cell(eigenval, n):
"""
Create a Jordan block:
Examples
========
>>> from sympy.matrices import jordan_cell
>>> from sympy.abc import x
>>> jordan_cell(x, 4)
Matrix([
[x, 1, 0, 0],
[0, x, 1, 0],
[0, 0, x, 1],
[0, 0, 0, x]])
"""
return Matrix.jordan_block(size=n, eigenvalue=eigenval)
def matrix_multiply_elementwise(A, B):
"""Return the Hadamard product (elementwise product) of A and B
>>> from sympy.matrices import matrix_multiply_elementwise
>>> from sympy.matrices import Matrix
>>> A = Matrix([[0, 1, 2], [3, 4, 5]])
>>> B = Matrix([[1, 10, 100], [100, 10, 1]])
>>> matrix_multiply_elementwise(A, B)
Matrix([
[ 0, 10, 200],
[300, 40, 5]])
See Also
========
sympy.matrices.common.MatrixCommon.__mul__
"""
return A.multiply_elementwise(B)
def ones(*args, **kwargs):
"""Returns a matrix of ones with ``rows`` rows and ``cols`` columns;
if ``cols`` is omitted a square matrix will be returned.
See Also
========
zeros
eye
diag
"""
if 'c' in kwargs:
kwargs['cols'] = kwargs.pop('c')
return Matrix.ones(*args, **kwargs)
def randMatrix(r, c=None, min=0, max=99, seed=None, symmetric=False,
percent=100, prng=None):
"""Create random matrix with dimensions ``r`` x ``c``. If ``c`` is omitted
the matrix will be square. If ``symmetric`` is True the matrix must be
square. If ``percent`` is less than 100 then only approximately the given
percentage of elements will be non-zero.
The pseudo-random number generator used to generate matrix is chosen in the
following way.
* If ``prng`` is supplied, it will be used as random number generator.
It should be an instance of ``random.Random``, or at least have
``randint`` and ``shuffle`` methods with same signatures.
* if ``prng`` is not supplied but ``seed`` is supplied, then new
``random.Random`` with given ``seed`` will be created;
* otherwise, a new ``random.Random`` with default seed will be used.
Examples
========
>>> from sympy.matrices import randMatrix
>>> randMatrix(3) # doctest:+SKIP
[25, 45, 27]
[44, 54, 9]
[23, 96, 46]
>>> randMatrix(3, 2) # doctest:+SKIP
[87, 29]
[23, 37]
[90, 26]
>>> randMatrix(3, 3, 0, 2) # doctest:+SKIP
[0, 2, 0]
[2, 0, 1]
[0, 0, 1]
>>> randMatrix(3, symmetric=True) # doctest:+SKIP
[85, 26, 29]
[26, 71, 43]
[29, 43, 57]
>>> A = randMatrix(3, seed=1)
>>> B = randMatrix(3, seed=2)
>>> A == B
False
>>> A == randMatrix(3, seed=1)
True
>>> randMatrix(3, symmetric=True, percent=50) # doctest:+SKIP
[77, 70, 0],
[70, 0, 0],
[ 0, 0, 88]
"""
# Note that ``Random()`` is equivalent to ``Random(None)``
prng = prng or random.Random(seed)
if c is None:
c = r
if symmetric and r != c:
raise ValueError('For symmetric matrices, r must equal c, but %i != %i' % (r, c))
ij = range(r * c)
if percent != 100:
ij = prng.sample(ij, int(len(ij)*percent // 100))
m = zeros(r, c)
if not symmetric:
for ijk in ij:
i, j = divmod(ijk, c)
m[i, j] = prng.randint(min, max)
else:
for ijk in ij:
i, j = divmod(ijk, c)
if i <= j:
m[i, j] = m[j, i] = prng.randint(min, max)
return m
def wronskian(functions, var, method='bareiss'):
"""
Compute Wronskian for [] of functions
::
| f1 f2 ... fn |
| f1' f2' ... fn' |
| . . . . |
W(f1, ..., fn) = | . . . . |
| . . . . |
| (n) (n) (n) |
| D (f1) D (f2) ... D (fn) |
see: https://en.wikipedia.org/wiki/Wronskian
See Also
========
sympy.matrices.matrices.MatrixCalculus.jacobian
hessian
"""
for index in range(0, len(functions)):
functions[index] = sympify(functions[index])
n = len(functions)
if n == 0:
return 1
W = Matrix(n, n, lambda i, j: functions[i].diff(var, j))
return W.det(method)
def zeros(*args, **kwargs):
"""Returns a matrix of zeros with ``rows`` rows and ``cols`` columns;
if ``cols`` is omitted a square matrix will be returned.
See Also
========
ones
eye
diag
"""
if 'c' in kwargs:
kwargs['cols'] = kwargs.pop('c')
return Matrix.zeros(*args, **kwargs)
|
85d7fafef44d03522389fdbc7d57d1124ec5e1ac4b58e1566886aaa9d92dbfb4 | from sympy.core.function import expand_mul
from sympy.core.symbol import Dummy, uniquely_named_symbol, symbols
from sympy.utilities.iterables import numbered_symbols
from .common import ShapeError, NonSquareMatrixError, NonInvertibleMatrixError
from .eigen import _fuzzy_positive_definite
from .utilities import _get_intermediate_simp, _iszero
def _diagonal_solve(M, rhs):
"""Solves ``Ax = B`` efficiently, where A is a diagonal Matrix,
with non-zero diagonal entries.
Examples
========
>>> from sympy.matrices import Matrix, eye
>>> A = eye(2)*2
>>> B = Matrix([[1, 2], [3, 4]])
>>> A.diagonal_solve(B) == B/2
True
See Also
========
sympy.matrices.dense.DenseMatrix.lower_triangular_solve
sympy.matrices.dense.DenseMatrix.upper_triangular_solve
gauss_jordan_solve
cholesky_solve
LDLsolve
LUsolve
QRsolve
pinv_solve
"""
if not M.is_diagonal():
raise TypeError("Matrix should be diagonal")
if rhs.rows != M.rows:
raise TypeError("Size mis-match")
return M._new(
rhs.rows, rhs.cols, lambda i, j: rhs[i, j] / M[i, i])
def _lower_triangular_solve(M, rhs):
"""Solves ``Ax = B``, where A is a lower triangular matrix.
See Also
========
upper_triangular_solve
gauss_jordan_solve
cholesky_solve
diagonal_solve
LDLsolve
LUsolve
QRsolve
pinv_solve
"""
from .dense import MutableDenseMatrix
if not M.is_square:
raise NonSquareMatrixError("Matrix must be square.")
if rhs.rows != M.rows:
raise ShapeError("Matrices size mismatch.")
if not M.is_lower:
raise ValueError("Matrix must be lower triangular.")
dps = _get_intermediate_simp()
X = MutableDenseMatrix.zeros(M.rows, rhs.cols)
for j in range(rhs.cols):
for i in range(M.rows):
if M[i, i] == 0:
raise TypeError("Matrix must be non-singular.")
X[i, j] = dps((rhs[i, j] - sum(M[i, k]*X[k, j]
for k in range(i))) / M[i, i])
return M._new(X)
def _lower_triangular_solve_sparse(M, rhs):
"""Solves ``Ax = B``, where A is a lower triangular matrix.
See Also
========
upper_triangular_solve
gauss_jordan_solve
cholesky_solve
diagonal_solve
LDLsolve
LUsolve
QRsolve
pinv_solve
"""
if not M.is_square:
raise NonSquareMatrixError("Matrix must be square.")
if rhs.rows != M.rows:
raise ShapeError("Matrices size mismatch.")
if not M.is_lower:
raise ValueError("Matrix must be lower triangular.")
dps = _get_intermediate_simp()
rows = [[] for i in range(M.rows)]
for i, j, v in M.row_list():
if i > j:
rows[i].append((j, v))
X = rhs.as_mutable()
for j in range(rhs.cols):
for i in range(rhs.rows):
for u, v in rows[i]:
X[i, j] -= v*X[u, j]
X[i, j] = dps(X[i, j] / M[i, i])
return M._new(X)
def _upper_triangular_solve(M, rhs):
"""Solves ``Ax = B``, where A is an upper triangular matrix.
See Also
========
lower_triangular_solve
gauss_jordan_solve
cholesky_solve
diagonal_solve
LDLsolve
LUsolve
QRsolve
pinv_solve
"""
from .dense import MutableDenseMatrix
if not M.is_square:
raise NonSquareMatrixError("Matrix must be square.")
if rhs.rows != M.rows:
raise ShapeError("Matrix size mismatch.")
if not M.is_upper:
raise TypeError("Matrix is not upper triangular.")
dps = _get_intermediate_simp()
X = MutableDenseMatrix.zeros(M.rows, rhs.cols)
for j in range(rhs.cols):
for i in reversed(range(M.rows)):
if M[i, i] == 0:
raise ValueError("Matrix must be non-singular.")
X[i, j] = dps((rhs[i, j] - sum(M[i, k]*X[k, j]
for k in range(i + 1, M.rows))) / M[i, i])
return M._new(X)
def _upper_triangular_solve_sparse(M, rhs):
"""Solves ``Ax = B``, where A is an upper triangular matrix.
See Also
========
lower_triangular_solve
gauss_jordan_solve
cholesky_solve
diagonal_solve
LDLsolve
LUsolve
QRsolve
pinv_solve
"""
if not M.is_square:
raise NonSquareMatrixError("Matrix must be square.")
if rhs.rows != M.rows:
raise ShapeError("Matrix size mismatch.")
if not M.is_upper:
raise TypeError("Matrix is not upper triangular.")
dps = _get_intermediate_simp()
rows = [[] for i in range(M.rows)]
for i, j, v in M.row_list():
if i < j:
rows[i].append((j, v))
X = rhs.as_mutable()
for j in range(rhs.cols):
for i in reversed(range(rhs.rows)):
for u, v in reversed(rows[i]):
X[i, j] -= v*X[u, j]
X[i, j] = dps(X[i, j] / M[i, i])
return M._new(X)
def _cholesky_solve(M, rhs):
"""Solves ``Ax = B`` using Cholesky decomposition,
for a general square non-singular matrix.
For a non-square matrix with rows > cols,
the least squares solution is returned.
See Also
========
sympy.matrices.dense.DenseMatrix.lower_triangular_solve
sympy.matrices.dense.DenseMatrix.upper_triangular_solve
gauss_jordan_solve
diagonal_solve
LDLsolve
LUsolve
QRsolve
pinv_solve
"""
if M.rows < M.cols:
raise NotImplementedError(
'Under-determined System. Try M.gauss_jordan_solve(rhs)')
hermitian = True
reform = False
if M.is_symmetric():
hermitian = False
elif not M.is_hermitian:
reform = True
if reform or _fuzzy_positive_definite(M) is False:
H = M.H
M = H.multiply(M)
rhs = H.multiply(rhs)
hermitian = not M.is_symmetric()
L = M.cholesky(hermitian=hermitian)
Y = L.lower_triangular_solve(rhs)
if hermitian:
return (L.H).upper_triangular_solve(Y)
else:
return (L.T).upper_triangular_solve(Y)
def _LDLsolve(M, rhs):
"""Solves ``Ax = B`` using LDL decomposition,
for a general square and non-singular matrix.
For a non-square matrix with rows > cols,
the least squares solution is returned.
Examples
========
>>> from sympy.matrices import Matrix, eye
>>> A = eye(2)*2
>>> B = Matrix([[1, 2], [3, 4]])
>>> A.LDLsolve(B) == B/2
True
See Also
========
sympy.matrices.dense.DenseMatrix.LDLdecomposition
sympy.matrices.dense.DenseMatrix.lower_triangular_solve
sympy.matrices.dense.DenseMatrix.upper_triangular_solve
gauss_jordan_solve
cholesky_solve
diagonal_solve
LUsolve
QRsolve
pinv_solve
"""
if M.rows < M.cols:
raise NotImplementedError(
'Under-determined System. Try M.gauss_jordan_solve(rhs)')
hermitian = True
reform = False
if M.is_symmetric():
hermitian = False
elif not M.is_hermitian:
reform = True
if reform or _fuzzy_positive_definite(M) is False:
H = M.H
M = H.multiply(M)
rhs = H.multiply(rhs)
hermitian = not M.is_symmetric()
L, D = M.LDLdecomposition(hermitian=hermitian)
Y = L.lower_triangular_solve(rhs)
Z = D.diagonal_solve(Y)
if hermitian:
return (L.H).upper_triangular_solve(Z)
else:
return (L.T).upper_triangular_solve(Z)
def _LUsolve(M, rhs, iszerofunc=_iszero):
"""Solve the linear system ``Ax = rhs`` for ``x`` where ``A = M``.
This is for symbolic matrices, for real or complex ones use
mpmath.lu_solve or mpmath.qr_solve.
See Also
========
sympy.matrices.dense.DenseMatrix.lower_triangular_solve
sympy.matrices.dense.DenseMatrix.upper_triangular_solve
gauss_jordan_solve
cholesky_solve
diagonal_solve
LDLsolve
QRsolve
pinv_solve
LUdecomposition
"""
if rhs.rows != M.rows:
raise ShapeError(
"``M`` and ``rhs`` must have the same number of rows.")
m = M.rows
n = M.cols
if m < n:
raise NotImplementedError("Underdetermined systems not supported.")
try:
A, perm = M.LUdecomposition_Simple(
iszerofunc=_iszero, rankcheck=True)
except ValueError:
raise NonInvertibleMatrixError("Matrix det == 0; not invertible.")
dps = _get_intermediate_simp()
b = rhs.permute_rows(perm).as_mutable()
# forward substitution, all diag entries are scaled to 1
for i in range(m):
for j in range(min(i, n)):
scale = A[i, j]
b.zip_row_op(i, j, lambda x, y: dps(x - y * scale))
# consistency check for overdetermined systems
if m > n:
for i in range(n, m):
for j in range(b.cols):
if not iszerofunc(b[i, j]):
raise ValueError("The system is inconsistent.")
b = b[0:n, :] # truncate zero rows if consistent
# backward substitution
for i in range(n - 1, -1, -1):
for j in range(i + 1, n):
scale = A[i, j]
b.zip_row_op(i, j, lambda x, y: dps(x - y * scale))
scale = A[i, i]
b.row_op(i, lambda x, _: dps(x / scale))
return rhs.__class__(b)
def _QRsolve(M, b):
"""Solve the linear system ``Ax = b``.
``M`` is the matrix ``A``, the method argument is the vector
``b``. The method returns the solution vector ``x``. If ``b`` is a
matrix, the system is solved for each column of ``b`` and the
return value is a matrix of the same shape as ``b``.
This method is slower (approximately by a factor of 2) but
more stable for floating-point arithmetic than the LUsolve method.
However, LUsolve usually uses an exact arithmetic, so you don't need
to use QRsolve.
This is mainly for educational purposes and symbolic matrices, for real
(or complex) matrices use mpmath.qr_solve.
See Also
========
sympy.matrices.dense.DenseMatrix.lower_triangular_solve
sympy.matrices.dense.DenseMatrix.upper_triangular_solve
gauss_jordan_solve
cholesky_solve
diagonal_solve
LDLsolve
LUsolve
pinv_solve
QRdecomposition
"""
dps = _get_intermediate_simp(expand_mul, expand_mul)
Q, R = M.QRdecomposition()
y = Q.T * b
# back substitution to solve R*x = y:
# We build up the result "backwards" in the vector 'x' and reverse it
# only in the end.
x = []
n = R.rows
for j in range(n - 1, -1, -1):
tmp = y[j, :]
for k in range(j + 1, n):
tmp -= R[j, k] * x[n - 1 - k]
tmp = dps(tmp)
x.append(tmp / R[j, j])
return M.vstack(*x[::-1])
def _gauss_jordan_solve(M, B, freevar=False):
"""
Solves ``Ax = B`` using Gauss Jordan elimination.
There may be zero, one, or infinite solutions. If one solution
exists, it will be returned. If infinite solutions exist, it will
be returned parametrically. If no solutions exist, It will throw
ValueError.
Parameters
==========
B : Matrix
The right hand side of the equation to be solved for. Must have
the same number of rows as matrix A.
freevar : boolean, optional
Flag, when set to `True` will return the indices of the free
variables in the solutions (column Matrix), for a system that is
undetermined (e.g. A has more columns than rows), for which
infinite solutions are possible, in terms of arbitrary
values of free variables. Default `False`.
Returns
=======
x : Matrix
The matrix that will satisfy ``Ax = B``. Will have as many rows as
matrix A has columns, and as many columns as matrix B.
params : Matrix
If the system is underdetermined (e.g. A has more columns than
rows), infinite solutions are possible, in terms of arbitrary
parameters. These arbitrary parameters are returned as params
Matrix.
free_var_index : List, optional
If the system is underdetermined (e.g. A has more columns than
rows), infinite solutions are possible, in terms of arbitrary
values of free variables. Then the indices of the free variables
in the solutions (column Matrix) are returned by free_var_index,
if the flag `freevar` is set to `True`.
Examples
========
>>> from sympy import Matrix
>>> A = Matrix([[1, 2, 1, 1], [1, 2, 2, -1], [2, 4, 0, 6]])
>>> B = Matrix([7, 12, 4])
>>> sol, params = A.gauss_jordan_solve(B)
>>> sol
Matrix([
[-2*tau0 - 3*tau1 + 2],
[ tau0],
[ 2*tau1 + 5],
[ tau1]])
>>> params
Matrix([
[tau0],
[tau1]])
>>> taus_zeroes = { tau:0 for tau in params }
>>> sol_unique = sol.xreplace(taus_zeroes)
>>> sol_unique
Matrix([
[2],
[0],
[5],
[0]])
>>> A = Matrix([[1, 2, 3], [4, 5, 6], [7, 8, 10]])
>>> B = Matrix([3, 6, 9])
>>> sol, params = A.gauss_jordan_solve(B)
>>> sol
Matrix([
[-1],
[ 2],
[ 0]])
>>> params
Matrix(0, 1, [])
>>> A = Matrix([[2, -7], [-1, 4]])
>>> B = Matrix([[-21, 3], [12, -2]])
>>> sol, params = A.gauss_jordan_solve(B)
>>> sol
Matrix([
[0, -2],
[3, -1]])
>>> params
Matrix(0, 2, [])
>>> from sympy import Matrix
>>> A = Matrix([[1, 2, 1, 1], [1, 2, 2, -1], [2, 4, 0, 6]])
>>> B = Matrix([7, 12, 4])
>>> sol, params, freevars = A.gauss_jordan_solve(B, freevar=True)
>>> sol
Matrix([
[-2*tau0 - 3*tau1 + 2],
[ tau0],
[ 2*tau1 + 5],
[ tau1]])
>>> params
Matrix([
[tau0],
[tau1]])
>>> freevars
[1, 3]
See Also
========
sympy.matrices.dense.DenseMatrix.lower_triangular_solve
sympy.matrices.dense.DenseMatrix.upper_triangular_solve
cholesky_solve
diagonal_solve
LDLsolve
LUsolve
QRsolve
pinv
References
==========
.. [1] https://en.wikipedia.org/wiki/Gaussian_elimination
"""
from sympy.matrices import Matrix, zeros
cls = M.__class__
aug = M.hstack(M.copy(), B.copy())
B_cols = B.cols
row, col = aug[:, :-B_cols].shape
# solve by reduced row echelon form
A, pivots = aug.rref(simplify=True)
A, v = A[:, :-B_cols], A[:, -B_cols:]
pivots = list(filter(lambda p: p < col, pivots))
rank = len(pivots)
# Get index of free symbols (free parameters)
# non-pivots columns are free variables
free_var_index = [c for c in range(A.cols) if c not in pivots]
# Bring to block form
permutation = Matrix(pivots + free_var_index).T
# check for existence of solutions
# rank of aug Matrix should be equal to rank of coefficient matrix
if not v[rank:, :].is_zero_matrix:
raise ValueError("Linear system has no solution")
# Free parameters
# what are current unnumbered free symbol names?
name = uniquely_named_symbol('tau', aug,
compare=lambda i: str(i).rstrip('1234567890'),
modify=lambda s: '_' + s).name
gen = numbered_symbols(name)
tau = Matrix([next(gen) for k in range((col - rank)*B_cols)]).reshape(
col - rank, B_cols)
# Full parametric solution
V = A[:rank, free_var_index]
vt = v[:rank, :]
free_sol = tau.vstack(vt - V * tau, tau)
# Undo permutation
sol = zeros(col, B_cols)
for k in range(col):
sol[permutation[k], :] = free_sol[k,:]
sol, tau = cls(sol), cls(tau)
if freevar:
return sol, tau, free_var_index
else:
return sol, tau
def _pinv_solve(M, B, arbitrary_matrix=None):
"""Solve ``Ax = B`` using the Moore-Penrose pseudoinverse.
There may be zero, one, or infinite solutions. If one solution
exists, it will be returned. If infinite solutions exist, one will
be returned based on the value of arbitrary_matrix. If no solutions
exist, the least-squares solution is returned.
Parameters
==========
B : Matrix
The right hand side of the equation to be solved for. Must have
the same number of rows as matrix A.
arbitrary_matrix : Matrix
If the system is underdetermined (e.g. A has more columns than
rows), infinite solutions are possible, in terms of an arbitrary
matrix. This parameter may be set to a specific matrix to use
for that purpose; if so, it must be the same shape as x, with as
many rows as matrix A has columns, and as many columns as matrix
B. If left as None, an appropriate matrix containing dummy
symbols in the form of ``wn_m`` will be used, with n and m being
row and column position of each symbol.
Returns
=======
x : Matrix
The matrix that will satisfy ``Ax = B``. Will have as many rows as
matrix A has columns, and as many columns as matrix B.
Examples
========
>>> from sympy import Matrix
>>> A = Matrix([[1, 2, 3], [4, 5, 6]])
>>> B = Matrix([7, 8])
>>> A.pinv_solve(B)
Matrix([
[ _w0_0/6 - _w1_0/3 + _w2_0/6 - 55/18],
[-_w0_0/3 + 2*_w1_0/3 - _w2_0/3 + 1/9],
[ _w0_0/6 - _w1_0/3 + _w2_0/6 + 59/18]])
>>> A.pinv_solve(B, arbitrary_matrix=Matrix([0, 0, 0]))
Matrix([
[-55/18],
[ 1/9],
[ 59/18]])
See Also
========
sympy.matrices.dense.DenseMatrix.lower_triangular_solve
sympy.matrices.dense.DenseMatrix.upper_triangular_solve
gauss_jordan_solve
cholesky_solve
diagonal_solve
LDLsolve
LUsolve
QRsolve
pinv
Notes
=====
This may return either exact solutions or least squares solutions.
To determine which, check ``A * A.pinv() * B == B``. It will be
True if exact solutions exist, and False if only a least-squares
solution exists. Be aware that the left hand side of that equation
may need to be simplified to correctly compare to the right hand
side.
References
==========
.. [1] https://en.wikipedia.org/wiki/Moore-Penrose_pseudoinverse#Obtaining_all_solutions_of_a_linear_system
"""
from sympy.matrices import eye
A = M
A_pinv = M.pinv()
if arbitrary_matrix is None:
rows, cols = A.cols, B.cols
w = symbols('w:{}_:{}'.format(rows, cols), cls=Dummy)
arbitrary_matrix = M.__class__(cols, rows, w).T
return A_pinv.multiply(B) + (eye(A.cols) -
A_pinv.multiply(A)).multiply(arbitrary_matrix)
def _solve(M, rhs, method='GJ'):
"""Solves linear equation where the unique solution exists.
Parameters
==========
rhs : Matrix
Vector representing the right hand side of the linear equation.
method : string, optional
If set to ``'GJ'`` or ``'GE'``, the Gauss-Jordan elimination will be
used, which is implemented in the routine ``gauss_jordan_solve``.
If set to ``'LU'``, ``LUsolve`` routine will be used.
If set to ``'QR'``, ``QRsolve`` routine will be used.
If set to ``'PINV'``, ``pinv_solve`` routine will be used.
It also supports the methods available for special linear systems
For positive definite systems:
If set to ``'CH'``, ``cholesky_solve`` routine will be used.
If set to ``'LDL'``, ``LDLsolve`` routine will be used.
To use a different method and to compute the solution via the
inverse, use a method defined in the .inv() docstring.
Returns
=======
solutions : Matrix
Vector representing the solution.
Raises
======
ValueError
If there is not a unique solution then a ``ValueError`` will be
raised.
If ``M`` is not square, a ``ValueError`` and a different routine
for solving the system will be suggested.
"""
if method == 'GJ' or method == 'GE':
try:
soln, param = M.gauss_jordan_solve(rhs)
if param:
raise NonInvertibleMatrixError("Matrix det == 0; not invertible. "
"Try ``M.gauss_jordan_solve(rhs)`` to obtain a parametric solution.")
except ValueError:
raise NonInvertibleMatrixError("Matrix det == 0; not invertible.")
return soln
elif method == 'LU':
return M.LUsolve(rhs)
elif method == 'CH':
return M.cholesky_solve(rhs)
elif method == 'QR':
return M.QRsolve(rhs)
elif method == 'LDL':
return M.LDLsolve(rhs)
elif method == 'PINV':
return M.pinv_solve(rhs)
else:
return M.inv(method=method).multiply(rhs)
def _solve_least_squares(M, rhs, method='CH'):
"""Return the least-square fit to the data.
Parameters
==========
rhs : Matrix
Vector representing the right hand side of the linear equation.
method : string or boolean, optional
If set to ``'CH'``, ``cholesky_solve`` routine will be used.
If set to ``'LDL'``, ``LDLsolve`` routine will be used.
If set to ``'QR'``, ``QRsolve`` routine will be used.
If set to ``'PINV'``, ``pinv_solve`` routine will be used.
Otherwise, the conjugate of ``M`` will be used to create a system
of equations that is passed to ``solve`` along with the hint
defined by ``method``.
Returns
=======
solutions : Matrix
Vector representing the solution.
Examples
========
>>> from sympy.matrices import Matrix, ones
>>> A = Matrix([1, 2, 3])
>>> B = Matrix([2, 3, 4])
>>> S = Matrix(A.row_join(B))
>>> S
Matrix([
[1, 2],
[2, 3],
[3, 4]])
If each line of S represent coefficients of Ax + By
and x and y are [2, 3] then S*xy is:
>>> r = S*Matrix([2, 3]); r
Matrix([
[ 8],
[13],
[18]])
But let's add 1 to the middle value and then solve for the
least-squares value of xy:
>>> xy = S.solve_least_squares(Matrix([8, 14, 18])); xy
Matrix([
[ 5/3],
[10/3]])
The error is given by S*xy - r:
>>> S*xy - r
Matrix([
[1/3],
[1/3],
[1/3]])
>>> _.norm().n(2)
0.58
If a different xy is used, the norm will be higher:
>>> xy += ones(2, 1)/10
>>> (S*xy - r).norm().n(2)
1.5
"""
if method == 'CH':
return M.cholesky_solve(rhs)
elif method == 'QR':
return M.QRsolve(rhs)
elif method == 'LDL':
return M.LDLsolve(rhs)
elif method == 'PINV':
return M.pinv_solve(rhs)
else:
t = M.H
return (t * M).solve(t * rhs, method=method)
|
6ee86772338c74c2f2a0c86e23b4b0d9f46f8c4706be494821da8c6fd6c3d56d | from collections.abc import Callable
from sympy.core.compatibility import as_int, is_sequence
from sympy.core.containers import Dict
from sympy.utilities.exceptions import SymPyDeprecationWarning
from .matrices import MatrixBase
from .repmatrix import MutableRepMatrix, RepMatrix
from .utilities import _iszero
from .decompositions import (
_liupc, _row_structure_symbolic_cholesky, _cholesky_sparse,
_LDLdecomposition_sparse)
from .solvers import (
_lower_triangular_solve_sparse, _upper_triangular_solve_sparse)
class SparseMatrix(RepMatrix):
"""
A sparse matrix (a matrix with a large number of zero elements).
Examples
========
>>> from sympy.matrices import SparseMatrix, ones
>>> SparseMatrix(2, 2, range(4))
Matrix([
[0, 1],
[2, 3]])
>>> SparseMatrix(2, 2, {(1, 1): 2})
Matrix([
[0, 0],
[0, 2]])
A SparseMatrix can be instantiated from a ragged list of lists:
>>> SparseMatrix([[1, 2, 3], [1, 2], [1]])
Matrix([
[1, 2, 3],
[1, 2, 0],
[1, 0, 0]])
For safety, one may include the expected size and then an error
will be raised if the indices of any element are out of range or
(for a flat list) if the total number of elements does not match
the expected shape:
>>> SparseMatrix(2, 2, [1, 2])
Traceback (most recent call last):
...
ValueError: List length (2) != rows*columns (4)
Here, an error is not raised because the list is not flat and no
element is out of range:
>>> SparseMatrix(2, 2, [[1, 2]])
Matrix([
[1, 2],
[0, 0]])
But adding another element to the first (and only) row will cause
an error to be raised:
>>> SparseMatrix(2, 2, [[1, 2, 3]])
Traceback (most recent call last):
...
ValueError: The location (0, 2) is out of designated range: (1, 1)
To autosize the matrix, pass None for rows:
>>> SparseMatrix(None, [[1, 2, 3]])
Matrix([[1, 2, 3]])
>>> SparseMatrix(None, {(1, 1): 1, (3, 3): 3})
Matrix([
[0, 0, 0, 0],
[0, 1, 0, 0],
[0, 0, 0, 0],
[0, 0, 0, 3]])
Values that are themselves a Matrix are automatically expanded:
>>> SparseMatrix(4, 4, {(1, 1): ones(2)})
Matrix([
[0, 0, 0, 0],
[0, 1, 1, 0],
[0, 1, 1, 0],
[0, 0, 0, 0]])
A ValueError is raised if the expanding matrix tries to overwrite
a different element already present:
>>> SparseMatrix(3, 3, {(0, 0): ones(2), (1, 1): 2})
Traceback (most recent call last):
...
ValueError: collision at (1, 1)
See Also
========
DenseMatrix
MutableSparseMatrix
ImmutableSparseMatrix
"""
@classmethod
def _handle_creation_inputs(cls, *args, **kwargs):
if len(args) == 1 and isinstance(args[0], MatrixBase):
rows = args[0].rows
cols = args[0].cols
smat = args[0].todok()
return rows, cols, smat
smat = {}
# autosizing
if len(args) == 2 and args[0] is None:
args = [None, None, args[1]]
if len(args) == 3:
r, c = args[:2]
if r is c is None:
rows = cols = None
elif None in (r, c):
raise ValueError(
'Pass rows=None and no cols for autosizing.')
else:
rows, cols = as_int(args[0]), as_int(args[1])
if isinstance(args[2], Callable):
op = args[2]
if None in (rows, cols):
raise ValueError(
"{} and {} must be integers for this "
"specification.".format(rows, cols))
row_indices = [cls._sympify(i) for i in range(rows)]
col_indices = [cls._sympify(j) for j in range(cols)]
for i in row_indices:
for j in col_indices:
value = cls._sympify(op(i, j))
if value != cls.zero:
smat[i, j] = value
return rows, cols, smat
elif isinstance(args[2], (dict, Dict)):
def update(i, j, v):
# update smat and make sure there are no collisions
if v:
if (i, j) in smat and v != smat[i, j]:
raise ValueError(
"There is a collision at {} for {} and {}."
.format((i, j), v, smat[i, j])
)
smat[i, j] = v
# manual copy, copy.deepcopy() doesn't work
for (r, c), v in args[2].items():
if isinstance(v, MatrixBase):
for (i, j), vv in v.todok().items():
update(r + i, c + j, vv)
elif isinstance(v, (list, tuple)):
_, _, smat = cls._handle_creation_inputs(v, **kwargs)
for i, j in smat:
update(r + i, c + j, smat[i, j])
else:
v = cls._sympify(v)
update(r, c, cls._sympify(v))
elif is_sequence(args[2]):
flat = not any(is_sequence(i) for i in args[2])
if not flat:
_, _, smat = \
cls._handle_creation_inputs(args[2], **kwargs)
else:
flat_list = args[2]
if len(flat_list) != rows * cols:
raise ValueError(
"The length of the flat list ({}) does not "
"match the specified size ({} * {})."
.format(len(flat_list), rows, cols)
)
for i in range(rows):
for j in range(cols):
value = flat_list[i*cols + j]
value = cls._sympify(value)
if value != cls.zero:
smat[i, j] = value
if rows is None: # autosizing
keys = smat.keys()
rows = max([r for r, _ in keys]) + 1 if keys else 0
cols = max([c for _, c in keys]) + 1 if keys else 0
else:
for i, j in smat.keys():
if i and i >= rows or j and j >= cols:
raise ValueError(
"The location {} is out of the designated range"
"[{}, {}]x[{}, {}]"
.format((i, j), 0, rows - 1, 0, cols - 1)
)
return rows, cols, smat
elif len(args) == 1 and isinstance(args[0], (list, tuple)):
# list of values or lists
v = args[0]
c = 0
for i, row in enumerate(v):
if not isinstance(row, (list, tuple)):
row = [row]
for j, vv in enumerate(row):
if vv != cls.zero:
smat[i, j] = cls._sympify(vv)
c = max(c, len(row))
rows = len(v) if c else 0
cols = c
return rows, cols, smat
else:
# handle full matrix forms with _handle_creation_inputs
rows, cols, mat = super()._handle_creation_inputs(*args)
for i in range(rows):
for j in range(cols):
value = mat[cols*i + j]
if value != cls.zero:
smat[i, j] = value
return rows, cols, smat
@property
def _smat(self):
SymPyDeprecationWarning(
feature="The private _smat attribute of SparseMatrix",
useinstead="the .todok() method",
issue=21715,
deprecated_since_version="1.9").warn()
return self.todok()
def _eval_inverse(self, **kwargs):
return self.inv(method=kwargs.get('method', 'LDL'),
iszerofunc=kwargs.get('iszerofunc', _iszero),
try_block_diag=kwargs.get('try_block_diag', False))
def applyfunc(self, f):
"""Apply a function to each element of the matrix.
Examples
========
>>> from sympy.matrices import SparseMatrix
>>> m = SparseMatrix(2, 2, lambda i, j: i*2+j)
>>> m
Matrix([
[0, 1],
[2, 3]])
>>> m.applyfunc(lambda i: 2*i)
Matrix([
[0, 2],
[4, 6]])
"""
if not callable(f):
raise TypeError("`f` must be callable.")
# XXX: This only applies the function to the nonzero elements of the
# matrix so is inconsistent with DenseMatrix.applyfunc e.g.
# zeros(2, 2).applyfunc(lambda x: x + 1)
dok = {}
for k, v in self.todok().items():
fv = f(v)
if fv != 0:
dok[k] = fv
return self._new(self.rows, self.cols, dok)
def as_immutable(self):
"""Returns an Immutable version of this Matrix."""
from .immutable import ImmutableSparseMatrix
return ImmutableSparseMatrix(self)
def as_mutable(self):
"""Returns a mutable version of this matrix.
Examples
========
>>> from sympy import ImmutableMatrix
>>> X = ImmutableMatrix([[1, 2], [3, 4]])
>>> Y = X.as_mutable()
>>> Y[1, 1] = 5 # Can set values in Y
>>> Y
Matrix([
[1, 2],
[3, 5]])
"""
return MutableSparseMatrix(self)
def col_list(self):
"""Returns a column-sorted list of non-zero elements of the matrix.
Examples
========
>>> from sympy.matrices import SparseMatrix
>>> a=SparseMatrix(((1, 2), (3, 4)))
>>> a
Matrix([
[1, 2],
[3, 4]])
>>> a.CL
[(0, 0, 1), (1, 0, 3), (0, 1, 2), (1, 1, 4)]
See Also
========
sympy.matrices.sparse.SparseMatrix.row_list
"""
return [tuple(k + (self[k],)) for k in sorted(list(self.todok().keys()), key=lambda k: list(reversed(k)))]
def nnz(self):
"""Returns the number of non-zero elements in Matrix."""
return len(self.todok())
def row_list(self):
"""Returns a row-sorted list of non-zero elements of the matrix.
Examples
========
>>> from sympy.matrices import SparseMatrix
>>> a = SparseMatrix(((1, 2), (3, 4)))
>>> a
Matrix([
[1, 2],
[3, 4]])
>>> a.RL
[(0, 0, 1), (0, 1, 2), (1, 0, 3), (1, 1, 4)]
See Also
========
sympy.matrices.sparse.SparseMatrix.col_list
"""
return [tuple(k + (self[k],)) for k in
sorted(self.todok().keys(), key=lambda k: list(k))]
def scalar_multiply(self, scalar):
"Scalar element-wise multiplication"
return scalar * self
def solve_least_squares(self, rhs, method='LDL'):
"""Return the least-square fit to the data.
By default the cholesky_solve routine is used (method='CH'); other
methods of matrix inversion can be used. To find out which are
available, see the docstring of the .inv() method.
Examples
========
>>> from sympy.matrices import SparseMatrix, Matrix, ones
>>> A = Matrix([1, 2, 3])
>>> B = Matrix([2, 3, 4])
>>> S = SparseMatrix(A.row_join(B))
>>> S
Matrix([
[1, 2],
[2, 3],
[3, 4]])
If each line of S represent coefficients of Ax + By
and x and y are [2, 3] then S*xy is:
>>> r = S*Matrix([2, 3]); r
Matrix([
[ 8],
[13],
[18]])
But let's add 1 to the middle value and then solve for the
least-squares value of xy:
>>> xy = S.solve_least_squares(Matrix([8, 14, 18])); xy
Matrix([
[ 5/3],
[10/3]])
The error is given by S*xy - r:
>>> S*xy - r
Matrix([
[1/3],
[1/3],
[1/3]])
>>> _.norm().n(2)
0.58
If a different xy is used, the norm will be higher:
>>> xy += ones(2, 1)/10
>>> (S*xy - r).norm().n(2)
1.5
"""
t = self.T
return (t*self).inv(method=method)*t*rhs
def solve(self, rhs, method='LDL'):
"""Return solution to self*soln = rhs using given inversion method.
For a list of possible inversion methods, see the .inv() docstring.
"""
if not self.is_square:
if self.rows < self.cols:
raise ValueError('Under-determined system.')
elif self.rows > self.cols:
raise ValueError('For over-determined system, M, having '
'more rows than columns, try M.solve_least_squares(rhs).')
else:
return self.inv(method=method).multiply(rhs)
RL = property(row_list, None, None, "Alternate faster representation")
CL = property(col_list, None, None, "Alternate faster representation")
def liupc(self):
return _liupc(self)
def row_structure_symbolic_cholesky(self):
return _row_structure_symbolic_cholesky(self)
def cholesky(self, hermitian=True):
return _cholesky_sparse(self, hermitian=hermitian)
def LDLdecomposition(self, hermitian=True):
return _LDLdecomposition_sparse(self, hermitian=hermitian)
def lower_triangular_solve(self, rhs):
return _lower_triangular_solve_sparse(self, rhs)
def upper_triangular_solve(self, rhs):
return _upper_triangular_solve_sparse(self, rhs)
liupc.__doc__ = _liupc.__doc__
row_structure_symbolic_cholesky.__doc__ = _row_structure_symbolic_cholesky.__doc__
cholesky.__doc__ = _cholesky_sparse.__doc__
LDLdecomposition.__doc__ = _LDLdecomposition_sparse.__doc__
lower_triangular_solve.__doc__ = lower_triangular_solve.__doc__
upper_triangular_solve.__doc__ = upper_triangular_solve.__doc__
class MutableSparseMatrix(SparseMatrix, MutableRepMatrix):
@classmethod
def _new(cls, *args, **kwargs):
rows, cols, smat = cls._handle_creation_inputs(*args, **kwargs)
rep = cls._smat_to_DomainMatrix(rows, cols, smat)
return cls._fromrep(rep)
|
4ac8b5c356c35efdbd14a6ea03e4917bc9f7658ea7fec1554fa29b6af28fc08d | import mpmath as mp
from sympy.core.add import Add
from sympy.core.basic import Basic
from sympy.core.compatibility import (
Callable, NotIterable, as_int, is_sequence)
from sympy.core.decorators import deprecated
from sympy.core.expr import Expr
from sympy.core.kind import _NumberKind, NumberKind, UndefinedKind
from sympy.core.mul import Mul
from sympy.core.power import Pow
from sympy.core.singleton import S
from sympy.core.symbol import Dummy, Symbol, uniquely_named_symbol
from sympy.core.sympify import sympify
from sympy.core.sympify import _sympify
from sympy.functions import exp, factorial, log
from sympy.functions.elementary.miscellaneous import Max, Min, sqrt
from sympy.functions.special.tensor_functions import KroneckerDelta
from sympy.polys import cancel
from sympy.printing import sstr
from sympy.printing.defaults import Printable
from sympy.simplify import simplify as _simplify
from sympy.utilities.exceptions import SymPyDeprecationWarning
from sympy.utilities.iterables import flatten
from sympy.utilities.misc import filldedent
from .common import (
MatrixCommon, MatrixError, NonSquareMatrixError, NonInvertibleMatrixError,
ShapeError, MatrixKind)
from .utilities import _iszero, _is_zero_after_expand_mul
from .determinant import (
_find_reasonable_pivot, _find_reasonable_pivot_naive,
_adjugate, _charpoly, _cofactor, _cofactor_matrix, _per,
_det, _det_bareiss, _det_berkowitz, _det_LU, _minor, _minor_submatrix)
from .reductions import _is_echelon, _echelon_form, _rank, _rref
from .subspaces import _columnspace, _nullspace, _rowspace, _orthogonalize
from .eigen import (
_eigenvals, _eigenvects,
_bidiagonalize, _bidiagonal_decomposition,
_is_diagonalizable, _diagonalize,
_is_positive_definite, _is_positive_semidefinite,
_is_negative_definite, _is_negative_semidefinite, _is_indefinite,
_jordan_form, _left_eigenvects, _singular_values)
from .decompositions import (
_rank_decomposition, _cholesky, _LDLdecomposition,
_LUdecomposition, _LUdecomposition_Simple, _LUdecompositionFF,
_singular_value_decomposition, _QRdecomposition, _upper_hessenberg_decomposition)
from .graph import (
_connected_components, _connected_components_decomposition,
_strongly_connected_components, _strongly_connected_components_decomposition)
from .solvers import (
_diagonal_solve, _lower_triangular_solve, _upper_triangular_solve,
_cholesky_solve, _LDLsolve, _LUsolve, _QRsolve, _gauss_jordan_solve,
_pinv_solve, _solve, _solve_least_squares)
from .inverse import (
_pinv, _inv_mod, _inv_ADJ, _inv_GE, _inv_LU, _inv_CH, _inv_LDL, _inv_QR,
_inv, _inv_block)
class DeferredVector(Symbol, NotIterable):
"""A vector whose components are deferred (e.g. for use with lambdify)
Examples
========
>>> from sympy import DeferredVector, lambdify
>>> X = DeferredVector( 'X' )
>>> X
X
>>> expr = (X[0] + 2, X[2] + 3)
>>> func = lambdify( X, expr)
>>> func( [1, 2, 3] )
(3, 6)
"""
def __getitem__(self, i):
if i == -0:
i = 0
if i < 0:
raise IndexError('DeferredVector index out of range')
component_name = '%s[%d]' % (self.name, i)
return Symbol(component_name)
def __str__(self):
return sstr(self)
def __repr__(self):
return "DeferredVector('%s')" % self.name
class MatrixDeterminant(MatrixCommon):
"""Provides basic matrix determinant operations. Should not be instantiated
directly. See ``determinant.py`` for their implementations."""
def _eval_det_bareiss(self, iszerofunc=_is_zero_after_expand_mul):
return _det_bareiss(self, iszerofunc=iszerofunc)
def _eval_det_berkowitz(self):
return _det_berkowitz(self)
def _eval_det_lu(self, iszerofunc=_iszero, simpfunc=None):
return _det_LU(self, iszerofunc=iszerofunc, simpfunc=simpfunc)
def _eval_determinant(self): # for expressions.determinant.Determinant
return _det(self)
def adjugate(self, method="berkowitz"):
return _adjugate(self, method=method)
def charpoly(self, x='lambda', simplify=_simplify):
return _charpoly(self, x=x, simplify=simplify)
def cofactor(self, i, j, method="berkowitz"):
return _cofactor(self, i, j, method=method)
def cofactor_matrix(self, method="berkowitz"):
return _cofactor_matrix(self, method=method)
def det(self, method="bareiss", iszerofunc=None):
return _det(self, method=method, iszerofunc=iszerofunc)
def per(self):
return _per(self)
def minor(self, i, j, method="berkowitz"):
return _minor(self, i, j, method=method)
def minor_submatrix(self, i, j):
return _minor_submatrix(self, i, j)
_find_reasonable_pivot.__doc__ = _find_reasonable_pivot.__doc__
_find_reasonable_pivot_naive.__doc__ = _find_reasonable_pivot_naive.__doc__
_eval_det_bareiss.__doc__ = _det_bareiss.__doc__
_eval_det_berkowitz.__doc__ = _det_berkowitz.__doc__
_eval_det_lu.__doc__ = _det_LU.__doc__
_eval_determinant.__doc__ = _det.__doc__
adjugate.__doc__ = _adjugate.__doc__
charpoly.__doc__ = _charpoly.__doc__
cofactor.__doc__ = _cofactor.__doc__
cofactor_matrix.__doc__ = _cofactor_matrix.__doc__
det.__doc__ = _det.__doc__
per.__doc__ = _per.__doc__
minor.__doc__ = _minor.__doc__
minor_submatrix.__doc__ = _minor_submatrix.__doc__
class MatrixReductions(MatrixDeterminant):
"""Provides basic matrix row/column operations. Should not be instantiated
directly. See ``reductions.py`` for some of their implementations."""
def echelon_form(self, iszerofunc=_iszero, simplify=False, with_pivots=False):
return _echelon_form(self, iszerofunc=iszerofunc, simplify=simplify,
with_pivots=with_pivots)
@property
def is_echelon(self):
return _is_echelon(self)
def rank(self, iszerofunc=_iszero, simplify=False):
return _rank(self, iszerofunc=iszerofunc, simplify=simplify)
def rref(self, iszerofunc=_iszero, simplify=False, pivots=True,
normalize_last=True):
return _rref(self, iszerofunc=iszerofunc, simplify=simplify,
pivots=pivots, normalize_last=normalize_last)
echelon_form.__doc__ = _echelon_form.__doc__
is_echelon.__doc__ = _is_echelon.__doc__
rank.__doc__ = _rank.__doc__
rref.__doc__ = _rref.__doc__
def _normalize_op_args(self, op, col, k, col1, col2, error_str="col"):
"""Validate the arguments for a row/column operation. ``error_str``
can be one of "row" or "col" depending on the arguments being parsed."""
if op not in ["n->kn", "n<->m", "n->n+km"]:
raise ValueError("Unknown {} operation '{}'. Valid col operations "
"are 'n->kn', 'n<->m', 'n->n+km'".format(error_str, op))
# define self_col according to error_str
self_cols = self.cols if error_str == 'col' else self.rows
# normalize and validate the arguments
if op == "n->kn":
col = col if col is not None else col1
if col is None or k is None:
raise ValueError("For a {0} operation 'n->kn' you must provide the "
"kwargs `{0}` and `k`".format(error_str))
if not 0 <= col < self_cols:
raise ValueError("This matrix doesn't have a {} '{}'".format(error_str, col))
elif op == "n<->m":
# we need two cols to swap. It doesn't matter
# how they were specified, so gather them together and
# remove `None`
cols = {col, k, col1, col2}.difference([None])
if len(cols) > 2:
# maybe the user left `k` by mistake?
cols = {col, col1, col2}.difference([None])
if len(cols) != 2:
raise ValueError("For a {0} operation 'n<->m' you must provide the "
"kwargs `{0}1` and `{0}2`".format(error_str))
col1, col2 = cols
if not 0 <= col1 < self_cols:
raise ValueError("This matrix doesn't have a {} '{}'".format(error_str, col1))
if not 0 <= col2 < self_cols:
raise ValueError("This matrix doesn't have a {} '{}'".format(error_str, col2))
elif op == "n->n+km":
col = col1 if col is None else col
col2 = col1 if col2 is None else col2
if col is None or col2 is None or k is None:
raise ValueError("For a {0} operation 'n->n+km' you must provide the "
"kwargs `{0}`, `k`, and `{0}2`".format(error_str))
if col == col2:
raise ValueError("For a {0} operation 'n->n+km' `{0}` and `{0}2` must "
"be different.".format(error_str))
if not 0 <= col < self_cols:
raise ValueError("This matrix doesn't have a {} '{}'".format(error_str, col))
if not 0 <= col2 < self_cols:
raise ValueError("This matrix doesn't have a {} '{}'".format(error_str, col2))
else:
raise ValueError('invalid operation %s' % repr(op))
return op, col, k, col1, col2
def _eval_col_op_multiply_col_by_const(self, col, k):
def entry(i, j):
if j == col:
return k * self[i, j]
return self[i, j]
return self._new(self.rows, self.cols, entry)
def _eval_col_op_swap(self, col1, col2):
def entry(i, j):
if j == col1:
return self[i, col2]
elif j == col2:
return self[i, col1]
return self[i, j]
return self._new(self.rows, self.cols, entry)
def _eval_col_op_add_multiple_to_other_col(self, col, k, col2):
def entry(i, j):
if j == col:
return self[i, j] + k * self[i, col2]
return self[i, j]
return self._new(self.rows, self.cols, entry)
def _eval_row_op_swap(self, row1, row2):
def entry(i, j):
if i == row1:
return self[row2, j]
elif i == row2:
return self[row1, j]
return self[i, j]
return self._new(self.rows, self.cols, entry)
def _eval_row_op_multiply_row_by_const(self, row, k):
def entry(i, j):
if i == row:
return k * self[i, j]
return self[i, j]
return self._new(self.rows, self.cols, entry)
def _eval_row_op_add_multiple_to_other_row(self, row, k, row2):
def entry(i, j):
if i == row:
return self[i, j] + k * self[row2, j]
return self[i, j]
return self._new(self.rows, self.cols, entry)
def elementary_col_op(self, op="n->kn", col=None, k=None, col1=None, col2=None):
"""Performs the elementary column operation `op`.
`op` may be one of
* "n->kn" (column n goes to k*n)
* "n<->m" (swap column n and column m)
* "n->n+km" (column n goes to column n + k*column m)
Parameters
==========
op : string; the elementary row operation
col : the column to apply the column operation
k : the multiple to apply in the column operation
col1 : one column of a column swap
col2 : second column of a column swap or column "m" in the column operation
"n->n+km"
"""
op, col, k, col1, col2 = self._normalize_op_args(op, col, k, col1, col2, "col")
# now that we've validated, we're all good to dispatch
if op == "n->kn":
return self._eval_col_op_multiply_col_by_const(col, k)
if op == "n<->m":
return self._eval_col_op_swap(col1, col2)
if op == "n->n+km":
return self._eval_col_op_add_multiple_to_other_col(col, k, col2)
def elementary_row_op(self, op="n->kn", row=None, k=None, row1=None, row2=None):
"""Performs the elementary row operation `op`.
`op` may be one of
* "n->kn" (row n goes to k*n)
* "n<->m" (swap row n and row m)
* "n->n+km" (row n goes to row n + k*row m)
Parameters
==========
op : string; the elementary row operation
row : the row to apply the row operation
k : the multiple to apply in the row operation
row1 : one row of a row swap
row2 : second row of a row swap or row "m" in the row operation
"n->n+km"
"""
op, row, k, row1, row2 = self._normalize_op_args(op, row, k, row1, row2, "row")
# now that we've validated, we're all good to dispatch
if op == "n->kn":
return self._eval_row_op_multiply_row_by_const(row, k)
if op == "n<->m":
return self._eval_row_op_swap(row1, row2)
if op == "n->n+km":
return self._eval_row_op_add_multiple_to_other_row(row, k, row2)
class MatrixSubspaces(MatrixReductions):
"""Provides methods relating to the fundamental subspaces of a matrix.
Should not be instantiated directly. See ``subspaces.py`` for their
implementations."""
def columnspace(self, simplify=False):
return _columnspace(self, simplify=simplify)
def nullspace(self, simplify=False, iszerofunc=_iszero):
return _nullspace(self, simplify=simplify, iszerofunc=iszerofunc)
def rowspace(self, simplify=False):
return _rowspace(self, simplify=simplify)
# This is a classmethod but is converted to such later in order to allow
# assignment of __doc__ since that does not work for already wrapped
# classmethods in Python 3.6.
def orthogonalize(cls, *vecs, **kwargs):
return _orthogonalize(cls, *vecs, **kwargs)
columnspace.__doc__ = _columnspace.__doc__
nullspace.__doc__ = _nullspace.__doc__
rowspace.__doc__ = _rowspace.__doc__
orthogonalize.__doc__ = _orthogonalize.__doc__
orthogonalize = classmethod(orthogonalize) # type:ignore
class MatrixEigen(MatrixSubspaces):
"""Provides basic matrix eigenvalue/vector operations.
Should not be instantiated directly. See ``eigen.py`` for their
implementations."""
def eigenvals(self, error_when_incomplete=True, **flags):
return _eigenvals(self, error_when_incomplete=error_when_incomplete, **flags)
def eigenvects(self, error_when_incomplete=True, iszerofunc=_iszero, **flags):
return _eigenvects(self, error_when_incomplete=error_when_incomplete,
iszerofunc=iszerofunc, **flags)
def is_diagonalizable(self, reals_only=False, **kwargs):
return _is_diagonalizable(self, reals_only=reals_only, **kwargs)
def diagonalize(self, reals_only=False, sort=False, normalize=False):
return _diagonalize(self, reals_only=reals_only, sort=sort,
normalize=normalize)
def bidiagonalize(self, upper=True):
return _bidiagonalize(self, upper=upper)
def bidiagonal_decomposition(self, upper=True):
return _bidiagonal_decomposition(self, upper=upper)
@property
def is_positive_definite(self):
return _is_positive_definite(self)
@property
def is_positive_semidefinite(self):
return _is_positive_semidefinite(self)
@property
def is_negative_definite(self):
return _is_negative_definite(self)
@property
def is_negative_semidefinite(self):
return _is_negative_semidefinite(self)
@property
def is_indefinite(self):
return _is_indefinite(self)
def jordan_form(self, calc_transform=True, **kwargs):
return _jordan_form(self, calc_transform=calc_transform, **kwargs)
def left_eigenvects(self, **flags):
return _left_eigenvects(self, **flags)
def singular_values(self):
return _singular_values(self)
eigenvals.__doc__ = _eigenvals.__doc__
eigenvects.__doc__ = _eigenvects.__doc__
is_diagonalizable.__doc__ = _is_diagonalizable.__doc__
diagonalize.__doc__ = _diagonalize.__doc__
is_positive_definite.__doc__ = _is_positive_definite.__doc__
is_positive_semidefinite.__doc__ = _is_positive_semidefinite.__doc__
is_negative_definite.__doc__ = _is_negative_definite.__doc__
is_negative_semidefinite.__doc__ = _is_negative_semidefinite.__doc__
is_indefinite.__doc__ = _is_indefinite.__doc__
jordan_form.__doc__ = _jordan_form.__doc__
left_eigenvects.__doc__ = _left_eigenvects.__doc__
singular_values.__doc__ = _singular_values.__doc__
bidiagonalize.__doc__ = _bidiagonalize.__doc__
bidiagonal_decomposition.__doc__ = _bidiagonal_decomposition.__doc__
class MatrixCalculus(MatrixCommon):
"""Provides calculus-related matrix operations."""
def diff(self, *args, **kwargs):
"""Calculate the derivative of each element in the matrix.
``args`` will be passed to the ``integrate`` function.
Examples
========
>>> from sympy.matrices import Matrix
>>> from sympy.abc import x, y
>>> M = Matrix([[x, y], [1, 0]])
>>> M.diff(x)
Matrix([
[1, 0],
[0, 0]])
See Also
========
integrate
limit
"""
# XXX this should be handled here rather than in Derivative
from sympy.tensor.array.array_derivatives import ArrayDerivative
kwargs.setdefault('evaluate', True)
deriv = ArrayDerivative(self, *args, evaluate=True)
if not isinstance(self, Basic):
return deriv.as_mutable()
else:
return deriv
def _eval_derivative(self, arg):
return self.applyfunc(lambda x: x.diff(arg))
def integrate(self, *args, **kwargs):
"""Integrate each element of the matrix. ``args`` will
be passed to the ``integrate`` function.
Examples
========
>>> from sympy.matrices import Matrix
>>> from sympy.abc import x, y
>>> M = Matrix([[x, y], [1, 0]])
>>> M.integrate((x, ))
Matrix([
[x**2/2, x*y],
[ x, 0]])
>>> M.integrate((x, 0, 2))
Matrix([
[2, 2*y],
[2, 0]])
See Also
========
limit
diff
"""
return self.applyfunc(lambda x: x.integrate(*args, **kwargs))
def jacobian(self, X):
"""Calculates the Jacobian matrix (derivative of a vector-valued function).
Parameters
==========
``self`` : vector of expressions representing functions f_i(x_1, ..., x_n).
X : set of x_i's in order, it can be a list or a Matrix
Both ``self`` and X can be a row or a column matrix in any order
(i.e., jacobian() should always work).
Examples
========
>>> from sympy import sin, cos, Matrix
>>> from sympy.abc import rho, phi
>>> X = Matrix([rho*cos(phi), rho*sin(phi), rho**2])
>>> Y = Matrix([rho, phi])
>>> X.jacobian(Y)
Matrix([
[cos(phi), -rho*sin(phi)],
[sin(phi), rho*cos(phi)],
[ 2*rho, 0]])
>>> X = Matrix([rho*cos(phi), rho*sin(phi)])
>>> X.jacobian(Y)
Matrix([
[cos(phi), -rho*sin(phi)],
[sin(phi), rho*cos(phi)]])
See Also
========
hessian
wronskian
"""
if not isinstance(X, MatrixBase):
X = self._new(X)
# Both X and ``self`` can be a row or a column matrix, so we need to make
# sure all valid combinations work, but everything else fails:
if self.shape[0] == 1:
m = self.shape[1]
elif self.shape[1] == 1:
m = self.shape[0]
else:
raise TypeError("``self`` must be a row or a column matrix")
if X.shape[0] == 1:
n = X.shape[1]
elif X.shape[1] == 1:
n = X.shape[0]
else:
raise TypeError("X must be a row or a column matrix")
# m is the number of functions and n is the number of variables
# computing the Jacobian is now easy:
return self._new(m, n, lambda j, i: self[j].diff(X[i]))
def limit(self, *args):
"""Calculate the limit of each element in the matrix.
``args`` will be passed to the ``limit`` function.
Examples
========
>>> from sympy.matrices import Matrix
>>> from sympy.abc import x, y
>>> M = Matrix([[x, y], [1, 0]])
>>> M.limit(x, 2)
Matrix([
[2, y],
[1, 0]])
See Also
========
integrate
diff
"""
return self.applyfunc(lambda x: x.limit(*args))
# https://github.com/sympy/sympy/pull/12854
class MatrixDeprecated(MatrixCommon):
"""A class to house deprecated matrix methods."""
def _legacy_array_dot(self, b):
"""Compatibility function for deprecated behavior of ``matrix.dot(vector)``
"""
from .dense import Matrix
if not isinstance(b, MatrixBase):
if is_sequence(b):
if len(b) != self.cols and len(b) != self.rows:
raise ShapeError(
"Dimensions incorrect for dot product: %s, %s" % (
self.shape, len(b)))
return self.dot(Matrix(b))
else:
raise TypeError(
"`b` must be an ordered iterable or Matrix, not %s." %
type(b))
mat = self
if mat.cols == b.rows:
if b.cols != 1:
mat = mat.T
b = b.T
prod = flatten((mat * b).tolist())
return prod
if mat.cols == b.cols:
return mat.dot(b.T)
elif mat.rows == b.rows:
return mat.T.dot(b)
else:
raise ShapeError("Dimensions incorrect for dot product: %s, %s" % (
self.shape, b.shape))
def berkowitz_charpoly(self, x=Dummy('lambda'), simplify=_simplify):
return self.charpoly(x=x)
def berkowitz_det(self):
"""Computes determinant using Berkowitz method.
See Also
========
det
berkowitz
"""
return self.det(method='berkowitz')
def berkowitz_eigenvals(self, **flags):
"""Computes eigenvalues of a Matrix using Berkowitz method.
See Also
========
berkowitz
"""
return self.eigenvals(**flags)
def berkowitz_minors(self):
"""Computes principal minors using Berkowitz method.
See Also
========
berkowitz
"""
sign, minors = self.one, []
for poly in self.berkowitz():
minors.append(sign * poly[-1])
sign = -sign
return tuple(minors)
def berkowitz(self):
from sympy.matrices import zeros
berk = ((1,),)
if not self:
return berk
if not self.is_square:
raise NonSquareMatrixError()
A, N = self, self.rows
transforms = [0] * (N - 1)
for n in range(N, 1, -1):
T, k = zeros(n + 1, n), n - 1
R, C = -A[k, :k], A[:k, k]
A, a = A[:k, :k], -A[k, k]
items = [C]
for i in range(0, n - 2):
items.append(A * items[i])
for i, B in enumerate(items):
items[i] = (R * B)[0, 0]
items = [self.one, a] + items
for i in range(n):
T[i:, i] = items[:n - i + 1]
transforms[k - 1] = T
polys = [self._new([self.one, -A[0, 0]])]
for i, T in enumerate(transforms):
polys.append(T * polys[i])
return berk + tuple(map(tuple, polys))
def cofactorMatrix(self, method="berkowitz"):
return self.cofactor_matrix(method=method)
def det_bareis(self):
return _det_bareiss(self)
def det_LU_decomposition(self):
"""Compute matrix determinant using LU decomposition
Note that this method fails if the LU decomposition itself
fails. In particular, if the matrix has no inverse this method
will fail.
TODO: Implement algorithm for sparse matrices (SFF),
http://www.eecis.udel.edu/~saunders/papers/sffge/it5.ps.
See Also
========
det
det_bareiss
berkowitz_det
"""
return self.det(method='lu')
def jordan_cell(self, eigenval, n):
return self.jordan_block(size=n, eigenvalue=eigenval)
def jordan_cells(self, calc_transformation=True):
P, J = self.jordan_form()
return P, J.get_diag_blocks()
def minorEntry(self, i, j, method="berkowitz"):
return self.minor(i, j, method=method)
def minorMatrix(self, i, j):
return self.minor_submatrix(i, j)
def permuteBkwd(self, perm):
"""Permute the rows of the matrix with the given permutation in reverse."""
return self.permute_rows(perm, direction='backward')
def permuteFwd(self, perm):
"""Permute the rows of the matrix with the given permutation."""
return self.permute_rows(perm, direction='forward')
@Mul._kind_dispatcher.register(_NumberKind, MatrixKind)
def num_mat_mul(k1, k2):
"""
Return MatrixKind. The element kind is selected by recursive dispatching.
Do not need to dispatch in reversed order because KindDispatcher
searches for this automatically.
"""
# Deal with Mul._kind_dispatcher's commutativity
elemk = Mul._kind_dispatcher(NumberKind, k2.element_kind)
return MatrixKind(elemk)
@Mul._kind_dispatcher.register(MatrixKind, MatrixKind)
def mat_mat_mul(k1, k2):
"""
Return MatrixKind. The element kind is selected by recursive dispatching.
"""
elemk = Mul._kind_dispatcher(k1.element_kind, k2.element_kind)
return MatrixKind(elemk)
class MatrixBase(MatrixDeprecated,
MatrixCalculus,
MatrixEigen,
MatrixCommon,
Printable):
"""Base class for matrix objects."""
# Added just for numpy compatibility
__array_priority__ = 11
is_Matrix = True
_class_priority = 3
_sympify = staticmethod(sympify)
zero = S.Zero
one = S.One
@property
def kind(self):
elem_kinds = set(e.kind for e in self.flat())
if len(elem_kinds) == 1:
elemkind, = elem_kinds
else:
elemkind = UndefinedKind
return MatrixKind(elemkind)
def flat(self):
return [self[i, j] for i in range(self.rows) for j in range(self.cols)]
def __array__(self, dtype=object):
from .dense import matrix2numpy
return matrix2numpy(self, dtype=dtype)
def __len__(self):
"""Return the number of elements of ``self``.
Implemented mainly so bool(Matrix()) == False.
"""
return self.rows * self.cols
def _matrix_pow_by_jordan_blocks(self, num):
from sympy.matrices import diag, MutableMatrix
from sympy import binomial
def jordan_cell_power(jc, n):
N = jc.shape[0]
l = jc[0,0]
if l.is_zero:
if N == 1 and n.is_nonnegative:
jc[0,0] = l**n
elif not (n.is_integer and n.is_nonnegative):
raise NonInvertibleMatrixError("Non-invertible matrix can only be raised to a nonnegative integer")
else:
for i in range(N):
jc[0,i] = KroneckerDelta(i, n)
else:
for i in range(N):
bn = binomial(n, i)
if isinstance(bn, binomial):
bn = bn._eval_expand_func()
jc[0,i] = l**(n-i)*bn
for i in range(N):
for j in range(1, N-i):
jc[j,i+j] = jc [j-1,i+j-1]
P, J = self.jordan_form()
jordan_cells = J.get_diag_blocks()
# Make sure jordan_cells matrices are mutable:
jordan_cells = [MutableMatrix(j) for j in jordan_cells]
for j in jordan_cells:
jordan_cell_power(j, num)
return self._new(P.multiply(diag(*jordan_cells))
.multiply(P.inv()))
def __str__(self):
if self.rows == 0 or self.cols == 0:
return 'Matrix(%s, %s, [])' % (self.rows, self.cols)
return "Matrix(%s)" % str(self.tolist())
def _format_str(self, printer=None):
if not printer:
from sympy.printing.str import StrPrinter
printer = StrPrinter()
# Handle zero dimensions:
if self.rows == 0 or self.cols == 0:
return 'Matrix(%s, %s, [])' % (self.rows, self.cols)
if self.rows == 1:
return "Matrix([%s])" % self.table(printer, rowsep=',\n')
return "Matrix([\n%s])" % self.table(printer, rowsep=',\n')
@classmethod
def irregular(cls, ntop, *matrices, **kwargs):
"""Return a matrix filled by the given matrices which
are listed in order of appearance from left to right, top to
bottom as they first appear in the matrix. They must fill the
matrix completely.
Examples
========
>>> from sympy import ones, Matrix
>>> Matrix.irregular(3, ones(2,1), ones(3,3)*2, ones(2,2)*3,
... ones(1,1)*4, ones(2,2)*5, ones(1,2)*6, ones(1,2)*7)
Matrix([
[1, 2, 2, 2, 3, 3],
[1, 2, 2, 2, 3, 3],
[4, 2, 2, 2, 5, 5],
[6, 6, 7, 7, 5, 5]])
"""
from sympy.core.compatibility import as_int
ntop = as_int(ntop)
# make sure we are working with explicit matrices
b = [i.as_explicit() if hasattr(i, 'as_explicit') else i
for i in matrices]
q = list(range(len(b)))
dat = [i.rows for i in b]
active = [q.pop(0) for _ in range(ntop)]
cols = sum([b[i].cols for i in active])
rows = []
while any(dat):
r = []
for a, j in enumerate(active):
r.extend(b[j][-dat[j], :])
dat[j] -= 1
if dat[j] == 0 and q:
active[a] = q.pop(0)
if len(r) != cols:
raise ValueError(filldedent('''
Matrices provided do not appear to fill
the space completely.'''))
rows.append(r)
return cls._new(rows)
@classmethod
def _handle_ndarray(cls, arg):
# NumPy array or matrix or some other object that implements
# __array__. So let's first use this method to get a
# numpy.array() and then make a python list out of it.
arr = arg.__array__()
if len(arr.shape) == 2:
rows, cols = arr.shape[0], arr.shape[1]
flat_list = [cls._sympify(i) for i in arr.ravel()]
return rows, cols, flat_list
elif len(arr.shape) == 1:
flat_list = [cls._sympify(i) for i in arr]
return arr.shape[0], 1, flat_list
else:
raise NotImplementedError(
"SymPy supports just 1D and 2D matrices")
@classmethod
def _handle_creation_inputs(cls, *args, **kwargs):
"""Return the number of rows, cols and flat matrix elements.
Examples
========
>>> from sympy import Matrix, I
Matrix can be constructed as follows:
* from a nested list of iterables
>>> Matrix( ((1, 2+I), (3, 4)) )
Matrix([
[1, 2 + I],
[3, 4]])
* from un-nested iterable (interpreted as a column)
>>> Matrix( [1, 2] )
Matrix([
[1],
[2]])
* from un-nested iterable with dimensions
>>> Matrix(1, 2, [1, 2] )
Matrix([[1, 2]])
* from no arguments (a 0 x 0 matrix)
>>> Matrix()
Matrix(0, 0, [])
* from a rule
>>> Matrix(2, 2, lambda i, j: i/(j + 1) )
Matrix([
[0, 0],
[1, 1/2]])
See Also
========
irregular - filling a matrix with irregular blocks
"""
from sympy.matrices.sparse import SparseMatrix
from sympy.matrices.expressions.matexpr import MatrixSymbol
from sympy.matrices.expressions.blockmatrix import BlockMatrix
from sympy.utilities.iterables import reshape
flat_list = None
if len(args) == 1:
# Matrix(SparseMatrix(...))
if isinstance(args[0], SparseMatrix):
return args[0].rows, args[0].cols, flatten(args[0].tolist())
# Matrix(Matrix(...))
elif isinstance(args[0], MatrixBase):
return args[0].rows, args[0].cols, args[0].flat()
# Matrix(MatrixSymbol('X', 2, 2))
elif isinstance(args[0], Basic) and args[0].is_Matrix:
return args[0].rows, args[0].cols, args[0].as_explicit().flat()
elif isinstance(args[0], mp.matrix):
M = args[0]
flat_list = [cls._sympify(x) for x in M]
return M.rows, M.cols, flat_list
# Matrix(numpy.ones((2, 2)))
elif hasattr(args[0], "__array__"):
return cls._handle_ndarray(args[0])
# Matrix([1, 2, 3]) or Matrix([[1, 2], [3, 4]])
elif is_sequence(args[0]) \
and not isinstance(args[0], DeferredVector):
dat = list(args[0])
ismat = lambda i: isinstance(i, MatrixBase) and (
evaluate or
isinstance(i, BlockMatrix) or
isinstance(i, MatrixSymbol))
raw = lambda i: is_sequence(i) and not ismat(i)
evaluate = kwargs.get('evaluate', True)
if evaluate:
def do(x):
# make Block and Symbol explicit
if isinstance(x, (list, tuple)):
return type(x)([do(i) for i in x])
if isinstance(x, BlockMatrix) or \
isinstance(x, MatrixSymbol) and \
all(_.is_Integer for _ in x.shape):
return x.as_explicit()
return cls._sympify(x)
dat = do(dat)
if dat == [] or dat == [[]]:
rows = cols = 0
flat_list = []
elif not any(raw(i) or ismat(i) for i in dat):
# a column as a list of values
flat_list = [cls._sympify(i) for i in dat]
rows = len(flat_list)
cols = 1 if rows else 0
elif evaluate and all(ismat(i) for i in dat):
# a column as a list of matrices
ncol = {i.cols for i in dat if any(i.shape)}
if ncol:
if len(ncol) != 1:
raise ValueError('mismatched dimensions')
flat_list = [_ for i in dat for r in i.tolist() for _ in r]
cols = ncol.pop()
rows = len(flat_list)//cols
else:
rows = cols = 0
flat_list = []
elif evaluate and any(ismat(i) for i in dat):
ncol = set()
flat_list = []
for i in dat:
if ismat(i):
flat_list.extend(
[k for j in i.tolist() for k in j])
if any(i.shape):
ncol.add(i.cols)
elif raw(i):
if i:
ncol.add(len(i))
flat_list.extend(i)
else:
ncol.add(1)
flat_list.append(i)
if len(ncol) > 1:
raise ValueError('mismatched dimensions')
cols = ncol.pop()
rows = len(flat_list)//cols
else:
# list of lists; each sublist is a logical row
# which might consist of many rows if the values in
# the row are matrices
flat_list = []
ncol = set()
rows = cols = 0
for row in dat:
if not is_sequence(row) and \
not getattr(row, 'is_Matrix', False):
raise ValueError('expecting list of lists')
if hasattr(row, '__array__'):
if 0 in row.shape:
continue
elif not row:
continue
if evaluate and all(ismat(i) for i in row):
r, c, flatT = cls._handle_creation_inputs(
[i.T for i in row])
T = reshape(flatT, [c])
flat = \
[T[i][j] for j in range(c) for i in range(r)]
r, c = c, r
else:
r = 1
if getattr(row, 'is_Matrix', False):
c = 1
flat = [row]
else:
c = len(row)
flat = [cls._sympify(i) for i in row]
ncol.add(c)
if len(ncol) > 1:
raise ValueError('mismatched dimensions')
flat_list.extend(flat)
rows += r
cols = ncol.pop() if ncol else 0
elif len(args) == 3:
rows = as_int(args[0])
cols = as_int(args[1])
if rows < 0 or cols < 0:
raise ValueError("Cannot create a {} x {} matrix. "
"Both dimensions must be positive".format(rows, cols))
# Matrix(2, 2, lambda i, j: i+j)
if len(args) == 3 and isinstance(args[2], Callable):
op = args[2]
flat_list = []
for i in range(rows):
flat_list.extend(
[cls._sympify(op(cls._sympify(i), cls._sympify(j)))
for j in range(cols)])
# Matrix(2, 2, [1, 2, 3, 4])
elif len(args) == 3 and is_sequence(args[2]):
flat_list = args[2]
if len(flat_list) != rows * cols:
raise ValueError(
'List length should be equal to rows*columns')
flat_list = [cls._sympify(i) for i in flat_list]
# Matrix()
elif len(args) == 0:
# Empty Matrix
rows = cols = 0
flat_list = []
if flat_list is None:
raise TypeError(filldedent('''
Data type not understood; expecting list of lists
or lists of values.'''))
return rows, cols, flat_list
def _setitem(self, key, value):
"""Helper to set value at location given by key.
Examples
========
>>> from sympy import Matrix, I, zeros, ones
>>> m = Matrix(((1, 2+I), (3, 4)))
>>> m
Matrix([
[1, 2 + I],
[3, 4]])
>>> m[1, 0] = 9
>>> m
Matrix([
[1, 2 + I],
[9, 4]])
>>> m[1, 0] = [[0, 1]]
To replace row r you assign to position r*m where m
is the number of columns:
>>> M = zeros(4)
>>> m = M.cols
>>> M[3*m] = ones(1, m)*2; M
Matrix([
[0, 0, 0, 0],
[0, 0, 0, 0],
[0, 0, 0, 0],
[2, 2, 2, 2]])
And to replace column c you can assign to position c:
>>> M[2] = ones(m, 1)*4; M
Matrix([
[0, 0, 4, 0],
[0, 0, 4, 0],
[0, 0, 4, 0],
[2, 2, 4, 2]])
"""
from .dense import Matrix
is_slice = isinstance(key, slice)
i, j = key = self.key2ij(key)
is_mat = isinstance(value, MatrixBase)
if type(i) is slice or type(j) is slice:
if is_mat:
self.copyin_matrix(key, value)
return
if not isinstance(value, Expr) and is_sequence(value):
self.copyin_list(key, value)
return
raise ValueError('unexpected value: %s' % value)
else:
if (not is_mat and
not isinstance(value, Basic) and is_sequence(value)):
value = Matrix(value)
is_mat = True
if is_mat:
if is_slice:
key = (slice(*divmod(i, self.cols)),
slice(*divmod(j, self.cols)))
else:
key = (slice(i, i + value.rows),
slice(j, j + value.cols))
self.copyin_matrix(key, value)
else:
return i, j, self._sympify(value)
return
def add(self, b):
"""Return self + b """
return self + b
def condition_number(self):
"""Returns the condition number of a matrix.
This is the maximum singular value divided by the minimum singular value
Examples
========
>>> from sympy import Matrix, S
>>> A = Matrix([[1, 0, 0], [0, 10, 0], [0, 0, S.One/10]])
>>> A.condition_number()
100
See Also
========
singular_values
"""
if not self:
return self.zero
singularvalues = self.singular_values()
return Max(*singularvalues) / Min(*singularvalues)
def copy(self):
"""
Returns the copy of a matrix.
Examples
========
>>> from sympy import Matrix
>>> A = Matrix(2, 2, [1, 2, 3, 4])
>>> A.copy()
Matrix([
[1, 2],
[3, 4]])
"""
return self._new(self.rows, self.cols, self.flat())
def cross(self, b):
r"""
Return the cross product of ``self`` and ``b`` relaxing the condition
of compatible dimensions: if each has 3 elements, a matrix of the
same type and shape as ``self`` will be returned. If ``b`` has the same
shape as ``self`` then common identities for the cross product (like
`a \times b = - b \times a`) will hold.
Parameters
==========
b : 3x1 or 1x3 Matrix
See Also
========
dot
multiply
multiply_elementwise
"""
from sympy.matrices.expressions.matexpr import MatrixExpr
if not isinstance(b, MatrixBase) and not isinstance(b, MatrixExpr):
raise TypeError(
"{} must be a Matrix, not {}.".format(b, type(b)))
if not (self.rows * self.cols == b.rows * b.cols == 3):
raise ShapeError("Dimensions incorrect for cross product: %s x %s" %
((self.rows, self.cols), (b.rows, b.cols)))
else:
return self._new(self.rows, self.cols, (
(self[1] * b[2] - self[2] * b[1]),
(self[2] * b[0] - self[0] * b[2]),
(self[0] * b[1] - self[1] * b[0])))
@property
def D(self):
"""Return Dirac conjugate (if ``self.rows == 4``).
Examples
========
>>> from sympy import Matrix, I, eye
>>> m = Matrix((0, 1 + I, 2, 3))
>>> m.D
Matrix([[0, 1 - I, -2, -3]])
>>> m = (eye(4) + I*eye(4))
>>> m[0, 3] = 2
>>> m.D
Matrix([
[1 - I, 0, 0, 0],
[ 0, 1 - I, 0, 0],
[ 0, 0, -1 + I, 0],
[ 2, 0, 0, -1 + I]])
If the matrix does not have 4 rows an AttributeError will be raised
because this property is only defined for matrices with 4 rows.
>>> Matrix(eye(2)).D
Traceback (most recent call last):
...
AttributeError: Matrix has no attribute D.
See Also
========
sympy.matrices.common.MatrixCommon.conjugate: By-element conjugation
sympy.matrices.common.MatrixCommon.H: Hermite conjugation
"""
from sympy.physics.matrices import mgamma
if self.rows != 4:
# In Python 3.2, properties can only return an AttributeError
# so we can't raise a ShapeError -- see commit which added the
# first line of this inline comment. Also, there is no need
# for a message since MatrixBase will raise the AttributeError
raise AttributeError
return self.H * mgamma(0)
def dot(self, b, hermitian=None, conjugate_convention=None):
"""Return the dot or inner product of two vectors of equal length.
Here ``self`` must be a ``Matrix`` of size 1 x n or n x 1, and ``b``
must be either a matrix of size 1 x n, n x 1, or a list/tuple of length n.
A scalar is returned.
By default, ``dot`` does not conjugate ``self`` or ``b``, even if there are
complex entries. Set ``hermitian=True`` (and optionally a ``conjugate_convention``)
to compute the hermitian inner product.
Possible kwargs are ``hermitian`` and ``conjugate_convention``.
If ``conjugate_convention`` is ``"left"``, ``"math"`` or ``"maths"``,
the conjugate of the first vector (``self``) is used. If ``"right"``
or ``"physics"`` is specified, the conjugate of the second vector ``b`` is used.
Examples
========
>>> from sympy import Matrix
>>> M = Matrix([[1, 2, 3], [4, 5, 6], [7, 8, 9]])
>>> v = Matrix([1, 1, 1])
>>> M.row(0).dot(v)
6
>>> M.col(0).dot(v)
12
>>> v = [3, 2, 1]
>>> M.row(0).dot(v)
10
>>> from sympy import I
>>> q = Matrix([1*I, 1*I, 1*I])
>>> q.dot(q, hermitian=False)
-3
>>> q.dot(q, hermitian=True)
3
>>> q1 = Matrix([1, 1, 1*I])
>>> q.dot(q1, hermitian=True, conjugate_convention="maths")
1 - 2*I
>>> q.dot(q1, hermitian=True, conjugate_convention="physics")
1 + 2*I
See Also
========
cross
multiply
multiply_elementwise
"""
from .dense import Matrix
if not isinstance(b, MatrixBase):
if is_sequence(b):
if len(b) != self.cols and len(b) != self.rows:
raise ShapeError(
"Dimensions incorrect for dot product: %s, %s" % (
self.shape, len(b)))
return self.dot(Matrix(b))
else:
raise TypeError(
"`b` must be an ordered iterable or Matrix, not %s." %
type(b))
mat = self
if (1 not in mat.shape) or (1 not in b.shape) :
SymPyDeprecationWarning(
feature="Dot product of non row/column vectors",
issue=13815,
deprecated_since_version="1.2",
useinstead="* to take matrix products").warn()
return mat._legacy_array_dot(b)
if len(mat) != len(b):
raise ShapeError("Dimensions incorrect for dot product: %s, %s" % (self.shape, b.shape))
n = len(mat)
if mat.shape != (1, n):
mat = mat.reshape(1, n)
if b.shape != (n, 1):
b = b.reshape(n, 1)
# Now ``mat`` is a row vector and ``b`` is a column vector.
# If it so happens that only conjugate_convention is passed
# then automatically set hermitian to True. If only hermitian
# is true but no conjugate_convention is not passed then
# automatically set it to ``"maths"``
if conjugate_convention is not None and hermitian is None:
hermitian = True
if hermitian and conjugate_convention is None:
conjugate_convention = "maths"
if hermitian == True:
if conjugate_convention in ("maths", "left", "math"):
mat = mat.conjugate()
elif conjugate_convention in ("physics", "right"):
b = b.conjugate()
else:
raise ValueError("Unknown conjugate_convention was entered."
" conjugate_convention must be one of the"
" following: math, maths, left, physics or right.")
return (mat * b)[0]
def dual(self):
"""Returns the dual of a matrix, which is:
``(1/2)*levicivita(i, j, k, l)*M(k, l)`` summed over indices `k` and `l`
Since the levicivita method is anti_symmetric for any pairwise
exchange of indices, the dual of a symmetric matrix is the zero
matrix. Strictly speaking the dual defined here assumes that the
'matrix' `M` is a contravariant anti_symmetric second rank tensor,
so that the dual is a covariant second rank tensor.
"""
from sympy import LeviCivita
from sympy.matrices import zeros
M, n = self[:, :], self.rows
work = zeros(n)
if self.is_symmetric():
return work
for i in range(1, n):
for j in range(1, n):
acum = 0
for k in range(1, n):
acum += LeviCivita(i, j, 0, k) * M[0, k]
work[i, j] = acum
work[j, i] = -acum
for l in range(1, n):
acum = 0
for a in range(1, n):
for b in range(1, n):
acum += LeviCivita(0, l, a, b) * M[a, b]
acum /= 2
work[0, l] = -acum
work[l, 0] = acum
return work
def _eval_matrix_exp_jblock(self):
"""A helper function to compute an exponential of a Jordan block
matrix
Examples
========
>>> from sympy import Symbol, Matrix
>>> l = Symbol('lamda')
A trivial example of 1*1 Jordan block:
>>> m = Matrix.jordan_block(1, l)
>>> m._eval_matrix_exp_jblock()
Matrix([[exp(lamda)]])
An example of 3*3 Jordan block:
>>> m = Matrix.jordan_block(3, l)
>>> m._eval_matrix_exp_jblock()
Matrix([
[exp(lamda), exp(lamda), exp(lamda)/2],
[ 0, exp(lamda), exp(lamda)],
[ 0, 0, exp(lamda)]])
References
==========
.. [1] https://en.wikipedia.org/wiki/Matrix_function#Jordan_decomposition
"""
size = self.rows
l = self[0, 0]
exp_l = exp(l)
bands = {i: exp_l / factorial(i) for i in range(size)}
from .sparsetools import banded
return self.__class__(banded(size, bands))
def analytic_func(self, f, x):
"""
Computes f(A) where A is a Square Matrix
and f is an analytic function.
Examples
========
>>> from sympy import Symbol, Matrix, S, log
>>> x = Symbol('x')
>>> m = Matrix([[S(5)/4, S(3)/4], [S(3)/4, S(5)/4]])
>>> f = log(x)
>>> m.analytic_func(f, x)
Matrix([
[ 0, log(2)],
[log(2), 0]])
Parameters
==========
f : Expr
Analytic Function
x : Symbol
parameter of f
"""
from sympy import diff
f, x = _sympify(f), _sympify(x)
if not self.is_square:
raise NonSquareMatrixError
if not x.is_symbol:
raise ValueError("{} must be a symbol.".format(x))
if x not in f.free_symbols:
raise ValueError(
"{} must be a parameter of {}.".format(x, f))
if x in self.free_symbols:
raise ValueError(
"{} must not be a parameter of {}.".format(x, self))
eigen = self.eigenvals()
max_mul = max(eigen.values())
derivative = {}
dd = f
for i in range(max_mul - 1):
dd = diff(dd, x)
derivative[i + 1] = dd
n = self.shape[0]
r = self.zeros(n)
f_val = self.zeros(n, 1)
row = 0
for i in eigen:
mul = eigen[i]
f_val[row] = f.subs(x, i)
if f_val[row].is_number and not f_val[row].is_complex:
raise ValueError(
"Cannot evaluate the function because the "
"function {} is not analytic at the given "
"eigenvalue {}".format(f, f_val[row]))
val = 1
for a in range(n):
r[row, a] = val
val *= i
if mul > 1:
coe = [1 for ii in range(n)]
deri = 1
while mul > 1:
row = row + 1
mul -= 1
d_i = derivative[deri].subs(x, i)
if d_i.is_number and not d_i.is_complex:
raise ValueError(
"Cannot evaluate the function because the "
"derivative {} is not analytic at the given "
"eigenvalue {}".format(derivative[deri], d_i))
f_val[row] = d_i
for a in range(n):
if a - deri + 1 <= 0:
r[row, a] = 0
coe[a] = 0
continue
coe[a] = coe[a]*(a - deri + 1)
r[row, a] = coe[a]*pow(i, a - deri)
deri += 1
row += 1
c = r.solve(f_val)
ans = self.zeros(n)
pre = self.eye(n)
for i in range(n):
ans = ans + c[i]*pre
pre *= self
return ans
def exp(self):
"""Return the exponential of a square matrix
Examples
========
>>> from sympy import Symbol, Matrix
>>> t = Symbol('t')
>>> m = Matrix([[0, 1], [-1, 0]]) * t
>>> m.exp()
Matrix([
[ exp(I*t)/2 + exp(-I*t)/2, -I*exp(I*t)/2 + I*exp(-I*t)/2],
[I*exp(I*t)/2 - I*exp(-I*t)/2, exp(I*t)/2 + exp(-I*t)/2]])
"""
if not self.is_square:
raise NonSquareMatrixError(
"Exponentiation is valid only for square matrices")
try:
P, J = self.jordan_form()
cells = J.get_diag_blocks()
except MatrixError:
raise NotImplementedError(
"Exponentiation is implemented only for matrices for which the Jordan normal form can be computed")
blocks = [cell._eval_matrix_exp_jblock() for cell in cells]
from sympy.matrices import diag
from sympy import re
eJ = diag(*blocks)
# n = self.rows
ret = P.multiply(eJ, dotprodsimp=None).multiply(P.inv(), dotprodsimp=None)
if all(value.is_real for value in self.values()):
return type(self)(re(ret))
else:
return type(self)(ret)
def _eval_matrix_log_jblock(self):
"""Helper function to compute logarithm of a jordan block.
Examples
========
>>> from sympy import Symbol, Matrix
>>> l = Symbol('lamda')
A trivial example of 1*1 Jordan block:
>>> m = Matrix.jordan_block(1, l)
>>> m._eval_matrix_log_jblock()
Matrix([[log(lamda)]])
An example of 3*3 Jordan block:
>>> m = Matrix.jordan_block(3, l)
>>> m._eval_matrix_log_jblock()
Matrix([
[log(lamda), 1/lamda, -1/(2*lamda**2)],
[ 0, log(lamda), 1/lamda],
[ 0, 0, log(lamda)]])
"""
size = self.rows
l = self[0, 0]
if l.is_zero:
raise MatrixError(
'Could not take logarithm or reciprocal for the given '
'eigenvalue {}'.format(l))
bands = {0: log(l)}
for i in range(1, size):
bands[i] = -((-l) ** -i) / i
from .sparsetools import banded
return self.__class__(banded(size, bands))
def log(self, simplify=cancel):
"""Return the logarithm of a square matrix
Parameters
==========
simplify : function, bool
The function to simplify the result with.
Default is ``cancel``, which is effective to reduce the
expression growing for taking reciprocals and inverses for
symbolic matrices.
Examples
========
>>> from sympy import S, Matrix
Examples for positive-definite matrices:
>>> m = Matrix([[1, 1], [0, 1]])
>>> m.log()
Matrix([
[0, 1],
[0, 0]])
>>> m = Matrix([[S(5)/4, S(3)/4], [S(3)/4, S(5)/4]])
>>> m.log()
Matrix([
[ 0, log(2)],
[log(2), 0]])
Examples for non positive-definite matrices:
>>> m = Matrix([[S(3)/4, S(5)/4], [S(5)/4, S(3)/4]])
>>> m.log()
Matrix([
[ I*pi/2, log(2) - I*pi/2],
[log(2) - I*pi/2, I*pi/2]])
>>> m = Matrix(
... [[0, 0, 0, 1],
... [0, 0, 1, 0],
... [0, 1, 0, 0],
... [1, 0, 0, 0]])
>>> m.log()
Matrix([
[ I*pi/2, 0, 0, -I*pi/2],
[ 0, I*pi/2, -I*pi/2, 0],
[ 0, -I*pi/2, I*pi/2, 0],
[-I*pi/2, 0, 0, I*pi/2]])
"""
if not self.is_square:
raise NonSquareMatrixError(
"Logarithm is valid only for square matrices")
try:
if simplify:
P, J = simplify(self).jordan_form()
else:
P, J = self.jordan_form()
cells = J.get_diag_blocks()
except MatrixError:
raise NotImplementedError(
"Logarithm is implemented only for matrices for which "
"the Jordan normal form can be computed")
blocks = [
cell._eval_matrix_log_jblock()
for cell in cells]
from sympy.matrices import diag
eJ = diag(*blocks)
if simplify:
ret = simplify(P * eJ * simplify(P.inv()))
ret = self.__class__(ret)
else:
ret = P * eJ * P.inv()
return ret
def is_nilpotent(self):
"""Checks if a matrix is nilpotent.
A matrix B is nilpotent if for some integer k, B**k is
a zero matrix.
Examples
========
>>> from sympy import Matrix
>>> a = Matrix([[0, 0, 0], [1, 0, 0], [1, 1, 0]])
>>> a.is_nilpotent()
True
>>> a = Matrix([[1, 0, 1], [1, 0, 0], [1, 1, 0]])
>>> a.is_nilpotent()
False
"""
if not self:
return True
if not self.is_square:
raise NonSquareMatrixError(
"Nilpotency is valid only for square matrices")
x = uniquely_named_symbol('x', self, modify=lambda s: '_' + s)
p = self.charpoly(x)
if p.args[0] == x ** self.rows:
return True
return False
def key2bounds(self, keys):
"""Converts a key with potentially mixed types of keys (integer and slice)
into a tuple of ranges and raises an error if any index is out of ``self``'s
range.
See Also
========
key2ij
"""
from sympy.matrices.common import a2idx as a2idx_ # Remove this line after deprecation of a2idx from matrices.py
islice, jslice = [isinstance(k, slice) for k in keys]
if islice:
if not self.rows:
rlo = rhi = 0
else:
rlo, rhi = keys[0].indices(self.rows)[:2]
else:
rlo = a2idx_(keys[0], self.rows)
rhi = rlo + 1
if jslice:
if not self.cols:
clo = chi = 0
else:
clo, chi = keys[1].indices(self.cols)[:2]
else:
clo = a2idx_(keys[1], self.cols)
chi = clo + 1
return rlo, rhi, clo, chi
def key2ij(self, key):
"""Converts key into canonical form, converting integers or indexable
items into valid integers for ``self``'s range or returning slices
unchanged.
See Also
========
key2bounds
"""
from sympy.matrices.common import a2idx as a2idx_ # Remove this line after deprecation of a2idx from matrices.py
if is_sequence(key):
if not len(key) == 2:
raise TypeError('key must be a sequence of length 2')
return [a2idx_(i, n) if not isinstance(i, slice) else i
for i, n in zip(key, self.shape)]
elif isinstance(key, slice):
return key.indices(len(self))[:2]
else:
return divmod(a2idx_(key, len(self)), self.cols)
def normalized(self, iszerofunc=_iszero):
"""Return the normalized version of ``self``.
Parameters
==========
iszerofunc : Function, optional
A function to determine whether ``self`` is a zero vector.
The default ``_iszero`` tests to see if each element is
exactly zero.
Returns
=======
Matrix
Normalized vector form of ``self``.
It has the same length as a unit vector. However, a zero vector
will be returned for a vector with norm 0.
Raises
======
ShapeError
If the matrix is not in a vector form.
See Also
========
norm
"""
if self.rows != 1 and self.cols != 1:
raise ShapeError("A Matrix must be a vector to normalize.")
norm = self.norm()
if iszerofunc(norm):
out = self.zeros(self.rows, self.cols)
else:
out = self.applyfunc(lambda i: i / norm)
return out
def norm(self, ord=None):
"""Return the Norm of a Matrix or Vector.
In the simplest case this is the geometric size of the vector
Other norms can be specified by the ord parameter
===== ============================ ==========================
ord norm for matrices norm for vectors
===== ============================ ==========================
None Frobenius norm 2-norm
'fro' Frobenius norm - does not exist
inf maximum row sum max(abs(x))
-inf -- min(abs(x))
1 maximum column sum as below
-1 -- as below
2 2-norm (largest sing. value) as below
-2 smallest singular value as below
other - does not exist sum(abs(x)**ord)**(1./ord)
===== ============================ ==========================
Examples
========
>>> from sympy import Matrix, Symbol, trigsimp, cos, sin, oo
>>> x = Symbol('x', real=True)
>>> v = Matrix([cos(x), sin(x)])
>>> trigsimp( v.norm() )
1
>>> v.norm(10)
(sin(x)**10 + cos(x)**10)**(1/10)
>>> A = Matrix([[1, 1], [1, 1]])
>>> A.norm(1) # maximum sum of absolute values of A is 2
2
>>> A.norm(2) # Spectral norm (max of |Ax|/|x| under 2-vector-norm)
2
>>> A.norm(-2) # Inverse spectral norm (smallest singular value)
0
>>> A.norm() # Frobenius Norm
2
>>> A.norm(oo) # Infinity Norm
2
>>> Matrix([1, -2]).norm(oo)
2
>>> Matrix([-1, 2]).norm(-oo)
1
See Also
========
normalized
"""
# Row or Column Vector Norms
vals = list(self.values()) or [0]
if self.rows == 1 or self.cols == 1:
if ord == 2 or ord is None: # Common case sqrt(<x, x>)
return sqrt(Add(*(abs(i) ** 2 for i in vals)))
elif ord == 1: # sum(abs(x))
return Add(*(abs(i) for i in vals))
elif ord is S.Infinity: # max(abs(x))
return Max(*[abs(i) for i in vals])
elif ord is S.NegativeInfinity: # min(abs(x))
return Min(*[abs(i) for i in vals])
# Otherwise generalize the 2-norm, Sum(x_i**ord)**(1/ord)
# Note that while useful this is not mathematically a norm
try:
return Pow(Add(*(abs(i) ** ord for i in vals)), S.One / ord)
except (NotImplementedError, TypeError):
raise ValueError("Expected order to be Number, Symbol, oo")
# Matrix Norms
else:
if ord == 1: # Maximum column sum
m = self.applyfunc(abs)
return Max(*[sum(m.col(i)) for i in range(m.cols)])
elif ord == 2: # Spectral Norm
# Maximum singular value
return Max(*self.singular_values())
elif ord == -2:
# Minimum singular value
return Min(*self.singular_values())
elif ord is S.Infinity: # Infinity Norm - Maximum row sum
m = self.applyfunc(abs)
return Max(*[sum(m.row(i)) for i in range(m.rows)])
elif (ord is None or isinstance(ord,
str) and ord.lower() in
['f', 'fro', 'frobenius', 'vector']):
# Reshape as vector and send back to norm function
return self.vec().norm(ord=2)
else:
raise NotImplementedError("Matrix Norms under development")
def print_nonzero(self, symb="X"):
"""Shows location of non-zero entries for fast shape lookup.
Examples
========
>>> from sympy.matrices import Matrix, eye
>>> m = Matrix(2, 3, lambda i, j: i*3+j)
>>> m
Matrix([
[0, 1, 2],
[3, 4, 5]])
>>> m.print_nonzero()
[ XX]
[XXX]
>>> m = eye(4)
>>> m.print_nonzero("x")
[x ]
[ x ]
[ x ]
[ x]
"""
s = []
for i in range(self.rows):
line = []
for j in range(self.cols):
if self[i, j] == 0:
line.append(" ")
else:
line.append(str(symb))
s.append("[%s]" % ''.join(line))
print('\n'.join(s))
def project(self, v):
"""Return the projection of ``self`` onto the line containing ``v``.
Examples
========
>>> from sympy import Matrix, S, sqrt
>>> V = Matrix([sqrt(3)/2, S.Half])
>>> x = Matrix([[1, 0]])
>>> V.project(x)
Matrix([[sqrt(3)/2, 0]])
>>> V.project(-x)
Matrix([[sqrt(3)/2, 0]])
"""
return v * (self.dot(v) / v.dot(v))
def table(self, printer, rowstart='[', rowend=']', rowsep='\n',
colsep=', ', align='right'):
r"""
String form of Matrix as a table.
``printer`` is the printer to use for on the elements (generally
something like StrPrinter())
``rowstart`` is the string used to start each row (by default '[').
``rowend`` is the string used to end each row (by default ']').
``rowsep`` is the string used to separate rows (by default a newline).
``colsep`` is the string used to separate columns (by default ', ').
``align`` defines how the elements are aligned. Must be one of 'left',
'right', or 'center'. You can also use '<', '>', and '^' to mean the
same thing, respectively.
This is used by the string printer for Matrix.
Examples
========
>>> from sympy import Matrix
>>> from sympy.printing.str import StrPrinter
>>> M = Matrix([[1, 2], [-33, 4]])
>>> printer = StrPrinter()
>>> M.table(printer)
'[ 1, 2]\n[-33, 4]'
>>> print(M.table(printer))
[ 1, 2]
[-33, 4]
>>> print(M.table(printer, rowsep=',\n'))
[ 1, 2],
[-33, 4]
>>> print('[%s]' % M.table(printer, rowsep=',\n'))
[[ 1, 2],
[-33, 4]]
>>> print(M.table(printer, colsep=' '))
[ 1 2]
[-33 4]
>>> print(M.table(printer, align='center'))
[ 1 , 2]
[-33, 4]
>>> print(M.table(printer, rowstart='{', rowend='}'))
{ 1, 2}
{-33, 4}
"""
# Handle zero dimensions:
if self.rows == 0 or self.cols == 0:
return '[]'
# Build table of string representations of the elements
res = []
# Track per-column max lengths for pretty alignment
maxlen = [0] * self.cols
for i in range(self.rows):
res.append([])
for j in range(self.cols):
s = printer._print(self[i, j])
res[-1].append(s)
maxlen[j] = max(len(s), maxlen[j])
# Patch strings together
align = {
'left': 'ljust',
'right': 'rjust',
'center': 'center',
'<': 'ljust',
'>': 'rjust',
'^': 'center',
}[align]
for i, row in enumerate(res):
for j, elem in enumerate(row):
row[j] = getattr(elem, align)(maxlen[j])
res[i] = rowstart + colsep.join(row) + rowend
return rowsep.join(res)
def rank_decomposition(self, iszerofunc=_iszero, simplify=False):
return _rank_decomposition(self, iszerofunc=iszerofunc,
simplify=simplify)
def cholesky(self, hermitian=True):
raise NotImplementedError('This function is implemented in DenseMatrix or SparseMatrix')
def LDLdecomposition(self, hermitian=True):
raise NotImplementedError('This function is implemented in DenseMatrix or SparseMatrix')
def LUdecomposition(self, iszerofunc=_iszero, simpfunc=None,
rankcheck=False):
return _LUdecomposition(self, iszerofunc=iszerofunc, simpfunc=simpfunc,
rankcheck=rankcheck)
def LUdecomposition_Simple(self, iszerofunc=_iszero, simpfunc=None,
rankcheck=False):
return _LUdecomposition_Simple(self, iszerofunc=iszerofunc,
simpfunc=simpfunc, rankcheck=rankcheck)
def LUdecompositionFF(self):
return _LUdecompositionFF(self)
def singular_value_decomposition(self):
return _singular_value_decomposition(self)
def QRdecomposition(self):
return _QRdecomposition(self)
def upper_hessenberg_decomposition(self):
return _upper_hessenberg_decomposition(self)
def diagonal_solve(self, rhs):
return _diagonal_solve(self, rhs)
def lower_triangular_solve(self, rhs):
raise NotImplementedError('This function is implemented in DenseMatrix or SparseMatrix')
def upper_triangular_solve(self, rhs):
raise NotImplementedError('This function is implemented in DenseMatrix or SparseMatrix')
def cholesky_solve(self, rhs):
return _cholesky_solve(self, rhs)
def LDLsolve(self, rhs):
return _LDLsolve(self, rhs)
def LUsolve(self, rhs, iszerofunc=_iszero):
return _LUsolve(self, rhs, iszerofunc=iszerofunc)
def QRsolve(self, b):
return _QRsolve(self, b)
def gauss_jordan_solve(self, B, freevar=False):
return _gauss_jordan_solve(self, B, freevar=freevar)
def pinv_solve(self, B, arbitrary_matrix=None):
return _pinv_solve(self, B, arbitrary_matrix=arbitrary_matrix)
def solve(self, rhs, method='GJ'):
return _solve(self, rhs, method=method)
def solve_least_squares(self, rhs, method='CH'):
return _solve_least_squares(self, rhs, method=method)
def pinv(self, method='RD'):
return _pinv(self, method=method)
def inv_mod(self, m):
return _inv_mod(self, m)
def inverse_ADJ(self, iszerofunc=_iszero):
return _inv_ADJ(self, iszerofunc=iszerofunc)
def inverse_BLOCK(self, iszerofunc=_iszero):
return _inv_block(self, iszerofunc=iszerofunc)
def inverse_GE(self, iszerofunc=_iszero):
return _inv_GE(self, iszerofunc=iszerofunc)
def inverse_LU(self, iszerofunc=_iszero):
return _inv_LU(self, iszerofunc=iszerofunc)
def inverse_CH(self, iszerofunc=_iszero):
return _inv_CH(self, iszerofunc=iszerofunc)
def inverse_LDL(self, iszerofunc=_iszero):
return _inv_LDL(self, iszerofunc=iszerofunc)
def inverse_QR(self, iszerofunc=_iszero):
return _inv_QR(self, iszerofunc=iszerofunc)
def inv(self, method=None, iszerofunc=_iszero, try_block_diag=False):
return _inv(self, method=method, iszerofunc=iszerofunc,
try_block_diag=try_block_diag)
def connected_components(self):
return _connected_components(self)
def connected_components_decomposition(self):
return _connected_components_decomposition(self)
def strongly_connected_components(self):
return _strongly_connected_components(self)
def strongly_connected_components_decomposition(self, lower=True):
return _strongly_connected_components_decomposition(self, lower=lower)
rank_decomposition.__doc__ = _rank_decomposition.__doc__
cholesky.__doc__ = _cholesky.__doc__
LDLdecomposition.__doc__ = _LDLdecomposition.__doc__
LUdecomposition.__doc__ = _LUdecomposition.__doc__
LUdecomposition_Simple.__doc__ = _LUdecomposition_Simple.__doc__
LUdecompositionFF.__doc__ = _LUdecompositionFF.__doc__
singular_value_decomposition.__doc__ = _singular_value_decomposition.__doc__
QRdecomposition.__doc__ = _QRdecomposition.__doc__
upper_hessenberg_decomposition.__doc__ = _upper_hessenberg_decomposition.__doc__
diagonal_solve.__doc__ = _diagonal_solve.__doc__
lower_triangular_solve.__doc__ = _lower_triangular_solve.__doc__
upper_triangular_solve.__doc__ = _upper_triangular_solve.__doc__
cholesky_solve.__doc__ = _cholesky_solve.__doc__
LDLsolve.__doc__ = _LDLsolve.__doc__
LUsolve.__doc__ = _LUsolve.__doc__
QRsolve.__doc__ = _QRsolve.__doc__
gauss_jordan_solve.__doc__ = _gauss_jordan_solve.__doc__
pinv_solve.__doc__ = _pinv_solve.__doc__
solve.__doc__ = _solve.__doc__
solve_least_squares.__doc__ = _solve_least_squares.__doc__
pinv.__doc__ = _pinv.__doc__
inv_mod.__doc__ = _inv_mod.__doc__
inverse_ADJ.__doc__ = _inv_ADJ.__doc__
inverse_GE.__doc__ = _inv_GE.__doc__
inverse_LU.__doc__ = _inv_LU.__doc__
inverse_CH.__doc__ = _inv_CH.__doc__
inverse_LDL.__doc__ = _inv_LDL.__doc__
inverse_QR.__doc__ = _inv_QR.__doc__
inverse_BLOCK.__doc__ = _inv_block.__doc__
inv.__doc__ = _inv.__doc__
connected_components.__doc__ = _connected_components.__doc__
connected_components_decomposition.__doc__ = \
_connected_components_decomposition.__doc__
strongly_connected_components.__doc__ = \
_strongly_connected_components.__doc__
strongly_connected_components_decomposition.__doc__ = \
_strongly_connected_components_decomposition.__doc__
@deprecated(
issue=15109,
useinstead="from sympy.matrices.common import classof",
deprecated_since_version="1.3")
def classof(A, B):
from sympy.matrices.common import classof as classof_
return classof_(A, B)
@deprecated(
issue=15109,
deprecated_since_version="1.3",
useinstead="from sympy.matrices.common import a2idx")
def a2idx(j, n=None):
from sympy.matrices.common import a2idx as a2idx_
return a2idx_(j, n)
|
4f773884656702f34d8d22dc9fb7dd4b867fe6424b600ef6247ef5e3cc5387de | from types import FunctionType
from collections import Counter
from mpmath import mp, workprec
from mpmath.libmp.libmpf import prec_to_dps
from sympy.core.compatibility import default_sort_key
from sympy.core.evalf import DEFAULT_MAXPREC, PrecisionExhausted
from sympy.core.logic import fuzzy_and, fuzzy_or
from sympy.core.numbers import Float
from sympy.core.sympify import _sympify
from sympy.functions.elementary.miscellaneous import sqrt
from sympy.polys import roots, CRootOf, ZZ, QQ, EX
from sympy.polys.matrices import DomainMatrix
from sympy.polys.matrices.eigen import dom_eigenvects, dom_eigenvects_to_sympy
from sympy.simplify import nsimplify, simplify as _simplify
from sympy.utilities.exceptions import SymPyDeprecationWarning
from .common import MatrixError, NonSquareMatrixError
from .determinant import _find_reasonable_pivot
from .utilities import _iszero
def _eigenvals_eigenvects_mpmath(M):
norm2 = lambda v: mp.sqrt(sum(i**2 for i in v))
v1 = None
prec = max([x._prec for x in M.atoms(Float)])
eps = 2**-prec
while prec < DEFAULT_MAXPREC:
with workprec(prec):
A = mp.matrix(M.evalf(n=prec_to_dps(prec)))
E, ER = mp.eig(A)
v2 = norm2([i for e in E for i in (mp.re(e), mp.im(e))])
if v1 is not None and mp.fabs(v1 - v2) < eps:
return E, ER
v1 = v2
prec *= 2
# we get here because the next step would have taken us
# past MAXPREC or because we never took a step; in case
# of the latter, we refuse to send back a solution since
# it would not have been verified; we also resist taking
# a small step to arrive exactly at MAXPREC since then
# the two calculations might be artificially close.
raise PrecisionExhausted
def _eigenvals_mpmath(M, multiple=False):
"""Compute eigenvalues using mpmath"""
E, _ = _eigenvals_eigenvects_mpmath(M)
result = [_sympify(x) for x in E]
if multiple:
return result
return dict(Counter(result))
def _eigenvects_mpmath(M):
E, ER = _eigenvals_eigenvects_mpmath(M)
result = []
for i in range(M.rows):
eigenval = _sympify(E[i])
eigenvect = _sympify(ER[:, i])
result.append((eigenval, 1, [eigenvect]))
return result
# This function is a candidate for caching if it gets implemented for matrices.
def _eigenvals(
M, error_when_incomplete=True, *, simplify=False, multiple=False,
rational=False, **flags):
r"""Compute eigenvalues of the matrix.
Parameters
==========
error_when_incomplete : bool, optional
If it is set to ``True``, it will raise an error if not all
eigenvalues are computed. This is caused by ``roots`` not returning
a full list of eigenvalues.
simplify : bool or function, optional
If it is set to ``True``, it attempts to return the most
simplified form of expressions returned by applying default
simplification method in every routine.
If it is set to ``False``, it will skip simplification in this
particular routine to save computation resources.
If a function is passed to, it will attempt to apply
the particular function as simplification method.
rational : bool, optional
If it is set to ``True``, every floating point numbers would be
replaced with rationals before computation. It can solve some
issues of ``roots`` routine not working well with floats.
multiple : bool, optional
If it is set to ``True``, the result will be in the form of a
list.
If it is set to ``False``, the result will be in the form of a
dictionary.
Returns
=======
eigs : list or dict
Eigenvalues of a matrix. The return format would be specified by
the key ``multiple``.
Raises
======
MatrixError
If not enough roots had got computed.
NonSquareMatrixError
If attempted to compute eigenvalues from a non-square matrix.
Examples
========
>>> from sympy.matrices import Matrix
>>> M = Matrix(3, 3, [0, 1, 1, 1, 0, 0, 1, 1, 1])
>>> M.eigenvals()
{-1: 1, 0: 1, 2: 1}
See Also
========
MatrixDeterminant.charpoly
eigenvects
Notes
=====
Eigenvalues of a matrix $A$ can be computed by solving a matrix
equation $\det(A - \lambda I) = 0$
It's not always possible to return radical solutions for
eigenvalues for matrices larger than $4, 4$ shape due to
Abel-Ruffini theorem.
If there is no radical solution is found for the eigenvalue,
it may return eigenvalues in the form of
:class:`sympy.polys.rootoftools.ComplexRootOf`.
"""
if not M:
if multiple:
return []
return {}
if not M.is_square:
raise NonSquareMatrixError("{} must be a square matrix.".format(M))
if M._rep.domain not in (ZZ, QQ):
# Skip this check for ZZ/QQ because it can be slow
if all(x.is_number for x in M) and M.has(Float):
return _eigenvals_mpmath(M, multiple=multiple)
if rational:
M = M.applyfunc(
lambda x: nsimplify(x, rational=True) if x.has(Float) else x)
if multiple:
return _eigenvals_list(
M, error_when_incomplete=error_when_incomplete, simplify=simplify,
**flags)
return _eigenvals_dict(
M, error_when_incomplete=error_when_incomplete, simplify=simplify,
**flags)
eigenvals_error_message = \
"It is not always possible to express the eigenvalues of a matrix " + \
"of size 5x5 or higher in radicals. " + \
"We have CRootOf, but domains other than the rationals are not " + \
"currently supported. " + \
"If there are no symbols in the matrix, " + \
"it should still be possible to compute numeric approximations " + \
"of the eigenvalues using " + \
"M.evalf().eigenvals() or M.charpoly().nroots()."
def _eigenvals_list(
M, error_when_incomplete=True, simplify=False, **flags):
iblocks = M.strongly_connected_components()
all_eigs = []
is_dom = M._rep.domain in (ZZ, QQ)
for b in iblocks:
# Fast path for a 1x1 block:
if is_dom and len(b) == 1:
index = b[0]
val = M[index, index]
all_eigs.append(val)
continue
block = M[b, b]
if isinstance(simplify, FunctionType):
charpoly = block.charpoly(simplify=simplify)
else:
charpoly = block.charpoly()
eigs = roots(charpoly, multiple=True, **flags)
if len(eigs) != block.rows:
degree = int(charpoly.degree())
f = charpoly.as_expr()
x = charpoly.gen
try:
eigs = [CRootOf(f, x, idx) for idx in range(degree)]
except NotImplementedError:
if error_when_incomplete:
raise MatrixError(eigenvals_error_message)
else:
eigs = []
all_eigs += eigs
if not simplify:
return all_eigs
if not isinstance(simplify, FunctionType):
simplify = _simplify
return [simplify(value) for value in all_eigs]
def _eigenvals_dict(
M, error_when_incomplete=True, simplify=False, **flags):
iblocks = M.strongly_connected_components()
all_eigs = {}
is_dom = M._rep.domain in (ZZ, QQ)
for b in iblocks:
# Fast path for a 1x1 block:
if is_dom and len(b) == 1:
index = b[0]
val = M[index, index]
all_eigs[val] = all_eigs.get(val, 0) + 1
continue
block = M[b, b]
if isinstance(simplify, FunctionType):
charpoly = block.charpoly(simplify=simplify)
else:
charpoly = block.charpoly()
eigs = roots(charpoly, multiple=False, **flags)
if sum(eigs.values()) != block.rows:
degree = int(charpoly.degree())
f = charpoly.as_expr()
x = charpoly.gen
try:
eigs = {CRootOf(f, x, idx): 1 for idx in range(degree)}
except NotImplementedError:
if error_when_incomplete:
raise MatrixError(eigenvals_error_message)
else:
eigs = {}
for k, v in eigs.items():
if k in all_eigs:
all_eigs[k] += v
else:
all_eigs[k] = v
if not simplify:
return all_eigs
if not isinstance(simplify, FunctionType):
simplify = _simplify
return {simplify(key): value for key, value in all_eigs.items()}
def _eigenspace(M, eigenval, iszerofunc=_iszero, simplify=False):
"""Get a basis for the eigenspace for a particular eigenvalue"""
m = M - M.eye(M.rows) * eigenval
ret = m.nullspace(iszerofunc=iszerofunc)
# The nullspace for a real eigenvalue should be non-trivial.
# If we didn't find an eigenvector, try once more a little harder
if len(ret) == 0 and simplify:
ret = m.nullspace(iszerofunc=iszerofunc, simplify=True)
if len(ret) == 0:
raise NotImplementedError(
"Can't evaluate eigenvector for eigenvalue {}".format(eigenval))
return ret
def _eigenvects_DOM(M, **kwargs):
DOM = DomainMatrix.from_Matrix(M, field=True, extension=True)
DOM = DOM.to_dense()
if DOM.domain != EX:
rational, algebraic = dom_eigenvects(DOM)
eigenvects = dom_eigenvects_to_sympy(
rational, algebraic, M.__class__, **kwargs)
eigenvects = sorted(eigenvects, key=lambda x: default_sort_key(x[0]))
return eigenvects
return None
def _eigenvects_sympy(M, iszerofunc, simplify=True, **flags):
eigenvals = M.eigenvals(rational=False, **flags)
# Make sure that we have all roots in radical form
for x in eigenvals:
if x.has(CRootOf):
raise MatrixError(
"Eigenvector computation is not implemented if the matrix have "
"eigenvalues in CRootOf form")
eigenvals = sorted(eigenvals.items(), key=default_sort_key)
ret = []
for val, mult in eigenvals:
vects = _eigenspace(M, val, iszerofunc=iszerofunc, simplify=simplify)
ret.append((val, mult, vects))
return ret
# This functions is a candidate for caching if it gets implemented for matrices.
def _eigenvects(M, error_when_incomplete=True, iszerofunc=_iszero, *, chop=False, **flags):
"""Compute eigenvectors of the matrix.
Parameters
==========
error_when_incomplete : bool, optional
Raise an error when not all eigenvalues are computed. This is
caused by ``roots`` not returning a full list of eigenvalues.
iszerofunc : function, optional
Specifies a zero testing function to be used in ``rref``.
Default value is ``_iszero``, which uses SymPy's naive and fast
default assumption handler.
It can also accept any user-specified zero testing function, if it
is formatted as a function which accepts a single symbolic argument
and returns ``True`` if it is tested as zero and ``False`` if it
is tested as non-zero, and ``None`` if it is undecidable.
simplify : bool or function, optional
If ``True``, ``as_content_primitive()`` will be used to tidy up
normalization artifacts.
It will also be used by the ``nullspace`` routine.
chop : bool or positive number, optional
If the matrix contains any Floats, they will be changed to Rationals
for computation purposes, but the answers will be returned after
being evaluated with evalf. The ``chop`` flag is passed to ``evalf``.
When ``chop=True`` a default precision will be used; a number will
be interpreted as the desired level of precision.
Returns
=======
ret : [(eigenval, multiplicity, eigenspace), ...]
A ragged list containing tuples of data obtained by ``eigenvals``
and ``nullspace``.
``eigenspace`` is a list containing the ``eigenvector`` for each
eigenvalue.
``eigenvector`` is a vector in the form of a ``Matrix``. e.g.
a vector of length 3 is returned as ``Matrix([a_1, a_2, a_3])``.
Raises
======
NotImplementedError
If failed to compute nullspace.
Examples
========
>>> from sympy.matrices import Matrix
>>> M = Matrix(3, 3, [0, 1, 1, 1, 0, 0, 1, 1, 1])
>>> M.eigenvects()
[(-1, 1, [Matrix([
[-1],
[ 1],
[ 0]])]), (0, 1, [Matrix([
[ 0],
[-1],
[ 1]])]), (2, 1, [Matrix([
[2/3],
[1/3],
[ 1]])])]
See Also
========
eigenvals
MatrixSubspaces.nullspace
"""
simplify = flags.get('simplify', True)
primitive = flags.get('simplify', False)
flags.pop('simplify', None) # remove this if it's there
flags.pop('multiple', None) # remove this if it's there
if not isinstance(simplify, FunctionType):
simpfunc = _simplify if simplify else lambda x: x
has_floats = M.has(Float)
if has_floats:
if all(x.is_number for x in M):
return _eigenvects_mpmath(M)
M = M.applyfunc(lambda x: nsimplify(x, rational=True))
ret = _eigenvects_DOM(M)
if ret is None:
ret = _eigenvects_sympy(M, iszerofunc, simplify=simplify, **flags)
if primitive:
# if the primitive flag is set, get rid of any common
# integer denominators
def denom_clean(l):
from sympy import gcd
return [(v / gcd(list(v))).applyfunc(simpfunc) for v in l]
ret = [(val, mult, denom_clean(es)) for val, mult, es in ret]
if has_floats:
# if we had floats to start with, turn the eigenvectors to floats
ret = [(val.evalf(chop=chop), mult, [v.evalf(chop=chop) for v in es])
for val, mult, es in ret]
return ret
def _is_diagonalizable_with_eigen(M, reals_only=False):
"""See _is_diagonalizable. This function returns the bool along with the
eigenvectors to avoid calculating them again in functions like
``diagonalize``."""
if not M.is_square:
return False, []
eigenvecs = M.eigenvects(simplify=True)
for val, mult, basis in eigenvecs:
if reals_only and not val.is_real: # if we have a complex eigenvalue
return False, eigenvecs
if mult != len(basis): # if the geometric multiplicity doesn't equal the algebraic
return False, eigenvecs
return True, eigenvecs
def _is_diagonalizable(M, reals_only=False, **kwargs):
"""Returns ``True`` if a matrix is diagonalizable.
Parameters
==========
reals_only : bool, optional
If ``True``, it tests whether the matrix can be diagonalized
to contain only real numbers on the diagonal.
If ``False``, it tests whether the matrix can be diagonalized
at all, even with numbers that may not be real.
Examples
========
Example of a diagonalizable matrix:
>>> from sympy import Matrix
>>> M = Matrix([[1, 2, 0], [0, 3, 0], [2, -4, 2]])
>>> M.is_diagonalizable()
True
Example of a non-diagonalizable matrix:
>>> M = Matrix([[0, 1], [0, 0]])
>>> M.is_diagonalizable()
False
Example of a matrix that is diagonalized in terms of non-real entries:
>>> M = Matrix([[0, 1], [-1, 0]])
>>> M.is_diagonalizable(reals_only=False)
True
>>> M.is_diagonalizable(reals_only=True)
False
See Also
========
is_diagonal
diagonalize
"""
if 'clear_cache' in kwargs:
SymPyDeprecationWarning(
feature='clear_cache',
deprecated_since_version=1.4,
issue=15887
).warn()
if 'clear_subproducts' in kwargs:
SymPyDeprecationWarning(
feature='clear_subproducts',
deprecated_since_version=1.4,
issue=15887
).warn()
if not M.is_square:
return False
if all(e.is_real for e in M) and M.is_symmetric():
return True
if all(e.is_complex for e in M) and M.is_hermitian:
return True
return _is_diagonalizable_with_eigen(M, reals_only=reals_only)[0]
#G&VL, Matrix Computations, Algo 5.4.2
def _householder_vector(x):
if not x.cols == 1:
raise ValueError("Input must be a column matrix")
v = x.copy()
v_plus = x.copy()
v_minus = x.copy()
q = x[0, 0] / abs(x[0, 0])
norm_x = x.norm()
v_plus[0, 0] = x[0, 0] + q * norm_x
v_minus[0, 0] = x[0, 0] - q * norm_x
if x[1:, 0].norm() == 0:
bet = 0
v[0, 0] = 1
else:
if v_plus.norm() <= v_minus.norm():
v = v_plus
else:
v = v_minus
v = v / v[0]
bet = 2 / (v.norm() ** 2)
return v, bet
def _bidiagonal_decmp_hholder(M):
m = M.rows
n = M.cols
A = M.as_mutable()
U, V = A.eye(m), A.eye(n)
for i in range(min(m, n)):
v, bet = _householder_vector(A[i:, i])
hh_mat = A.eye(m - i) - bet * v * v.H
A[i:, i:] = hh_mat * A[i:, i:]
temp = A.eye(m)
temp[i:, i:] = hh_mat
U = U * temp
if i + 1 <= n - 2:
v, bet = _householder_vector(A[i, i+1:].T)
hh_mat = A.eye(n - i - 1) - bet * v * v.H
A[i:, i+1:] = A[i:, i+1:] * hh_mat
temp = A.eye(n)
temp[i+1:, i+1:] = hh_mat
V = temp * V
return U, A, V
def _eval_bidiag_hholder(M):
m = M.rows
n = M.cols
A = M.as_mutable()
for i in range(min(m, n)):
v, bet = _householder_vector(A[i:, i])
hh_mat = A.eye(m-i) - bet * v * v.H
A[i:, i:] = hh_mat * A[i:, i:]
if i + 1 <= n - 2:
v, bet = _householder_vector(A[i, i+1:].T)
hh_mat = A.eye(n - i - 1) - bet * v * v.H
A[i:, i+1:] = A[i:, i+1:] * hh_mat
return A
def _bidiagonal_decomposition(M, upper=True):
"""
Returns (U,B,V.H)
$A = UBV^{H}$
where A is the input matrix, and B is its Bidiagonalized form
Note: Bidiagonal Computation can hang for symbolic matrices.
Parameters
==========
upper : bool. Whether to do upper bidiagnalization or lower.
True for upper and False for lower.
References
==========
1. Algorith 5.4.2, Matrix computations by Golub and Van Loan, 4th edition
2. Complex Matrix Bidiagonalization : https://github.com/vslobody/Householder-Bidiagonalization
"""
if type(upper) is not bool:
raise ValueError("upper must be a boolean")
if not upper:
X = _bidiagonal_decmp_hholder(M.H)
return X[2].H, X[1].H, X[0].H
return _bidiagonal_decmp_hholder(M)
def _bidiagonalize(M, upper=True):
"""
Returns $B$, the Bidiagonalized form of the input matrix.
Note: Bidiagonal Computation can hang for symbolic matrices.
Parameters
==========
upper : bool. Whether to do upper bidiagnalization or lower.
True for upper and False for lower.
References
==========
1. Algorith 5.4.2, Matrix computations by Golub and Van Loan, 4th edition
2. Complex Matrix Bidiagonalization : https://github.com/vslobody/Householder-Bidiagonalization
"""
if type(upper) is not bool:
raise ValueError("upper must be a boolean")
if not upper:
return _eval_bidiag_hholder(M.H).H
return _eval_bidiag_hholder(M)
def _diagonalize(M, reals_only=False, sort=False, normalize=False):
"""
Return (P, D), where D is diagonal and
D = P^-1 * M * P
where M is current matrix.
Parameters
==========
reals_only : bool. Whether to throw an error if complex numbers are need
to diagonalize. (Default: False)
sort : bool. Sort the eigenvalues along the diagonal. (Default: False)
normalize : bool. If True, normalize the columns of P. (Default: False)
Examples
========
>>> from sympy.matrices import Matrix
>>> M = Matrix(3, 3, [1, 2, 0, 0, 3, 0, 2, -4, 2])
>>> M
Matrix([
[1, 2, 0],
[0, 3, 0],
[2, -4, 2]])
>>> (P, D) = M.diagonalize()
>>> D
Matrix([
[1, 0, 0],
[0, 2, 0],
[0, 0, 3]])
>>> P
Matrix([
[-1, 0, -1],
[ 0, 0, -1],
[ 2, 1, 2]])
>>> P.inv() * M * P
Matrix([
[1, 0, 0],
[0, 2, 0],
[0, 0, 3]])
See Also
========
is_diagonal
is_diagonalizable
"""
if not M.is_square:
raise NonSquareMatrixError()
is_diagonalizable, eigenvecs = _is_diagonalizable_with_eigen(M,
reals_only=reals_only)
if not is_diagonalizable:
raise MatrixError("Matrix is not diagonalizable")
if sort:
eigenvecs = sorted(eigenvecs, key=default_sort_key)
p_cols, diag = [], []
for val, mult, basis in eigenvecs:
diag += [val] * mult
p_cols += basis
if normalize:
p_cols = [v / v.norm() for v in p_cols]
return M.hstack(*p_cols), M.diag(*diag)
def _fuzzy_positive_definite(M):
positive_diagonals = M._has_positive_diagonals()
if positive_diagonals is False:
return False
if positive_diagonals and M.is_strongly_diagonally_dominant:
return True
return None
def _fuzzy_positive_semidefinite(M):
nonnegative_diagonals = M._has_nonnegative_diagonals()
if nonnegative_diagonals is False:
return False
if nonnegative_diagonals and M.is_weakly_diagonally_dominant:
return True
return None
def _is_positive_definite(M):
if not M.is_hermitian:
if not M.is_square:
return False
M = M + M.H
fuzzy = _fuzzy_positive_definite(M)
if fuzzy is not None:
return fuzzy
return _is_positive_definite_GE(M)
def _is_positive_semidefinite(M):
if not M.is_hermitian:
if not M.is_square:
return False
M = M + M.H
fuzzy = _fuzzy_positive_semidefinite(M)
if fuzzy is not None:
return fuzzy
return _is_positive_semidefinite_cholesky(M)
def _is_negative_definite(M):
return _is_positive_definite(-M)
def _is_negative_semidefinite(M):
return _is_positive_semidefinite(-M)
def _is_indefinite(M):
if M.is_hermitian:
eigen = M.eigenvals()
args1 = [x.is_positive for x in eigen.keys()]
any_positive = fuzzy_or(args1)
args2 = [x.is_negative for x in eigen.keys()]
any_negative = fuzzy_or(args2)
return fuzzy_and([any_positive, any_negative])
elif M.is_square:
return (M + M.H).is_indefinite
return False
def _is_positive_definite_GE(M):
"""A division-free gaussian elimination method for testing
positive-definiteness."""
M = M.as_mutable()
size = M.rows
for i in range(size):
is_positive = M[i, i].is_positive
if is_positive is not True:
return is_positive
for j in range(i+1, size):
M[j, i+1:] = M[i, i] * M[j, i+1:] - M[j, i] * M[i, i+1:]
return True
def _is_positive_semidefinite_cholesky(M):
"""Uses Cholesky factorization with complete pivoting
References
==========
.. [1] http://eprints.ma.man.ac.uk/1199/1/covered/MIMS_ep2008_116.pdf
.. [2] https://www.value-at-risk.net/cholesky-factorization/
"""
M = M.as_mutable()
for k in range(M.rows):
diags = [M[i, i] for i in range(k, M.rows)]
pivot, pivot_val, nonzero, _ = _find_reasonable_pivot(diags)
if nonzero:
return None
if pivot is None:
for i in range(k+1, M.rows):
for j in range(k, M.cols):
iszero = M[i, j].is_zero
if iszero is None:
return None
elif iszero is False:
return False
return True
if M[k, k].is_negative or pivot_val.is_negative:
return False
if pivot > 0:
M.col_swap(k, k+pivot)
M.row_swap(k, k+pivot)
M[k, k] = sqrt(M[k, k])
M[k, k+1:] /= M[k, k]
M[k+1:, k+1:] -= M[k, k+1:].H * M[k, k+1:]
return M[-1, -1].is_nonnegative
_doc_positive_definite = \
r"""Finds out the definiteness of a matrix.
Explanation
===========
A square real matrix $A$ is:
- A positive definite matrix if $x^T A x > 0$
for all non-zero real vectors $x$.
- A positive semidefinite matrix if $x^T A x \geq 0$
for all non-zero real vectors $x$.
- A negative definite matrix if $x^T A x < 0$
for all non-zero real vectors $x$.
- A negative semidefinite matrix if $x^T A x \leq 0$
for all non-zero real vectors $x$.
- An indefinite matrix if there exists non-zero real vectors
$x, y$ with $x^T A x > 0 > y^T A y$.
A square complex matrix $A$ is:
- A positive definite matrix if $\text{re}(x^H A x) > 0$
for all non-zero complex vectors $x$.
- A positive semidefinite matrix if $\text{re}(x^H A x) \geq 0$
for all non-zero complex vectors $x$.
- A negative definite matrix if $\text{re}(x^H A x) < 0$
for all non-zero complex vectors $x$.
- A negative semidefinite matrix if $\text{re}(x^H A x) \leq 0$
for all non-zero complex vectors $x$.
- An indefinite matrix if there exists non-zero complex vectors
$x, y$ with $\text{re}(x^H A x) > 0 > \text{re}(y^H A y)$.
A matrix need not be symmetric or hermitian to be positive definite.
- A real non-symmetric matrix is positive definite if and only if
$\frac{A + A^T}{2}$ is positive definite.
- A complex non-hermitian matrix is positive definite if and only if
$\frac{A + A^H}{2}$ is positive definite.
And this extension can apply for all the definitions above.
However, for complex cases, you can restrict the definition of
$\text{re}(x^H A x) > 0$ to $x^H A x > 0$ and require the matrix
to be hermitian.
But we do not present this restriction for computation because you
can check ``M.is_hermitian`` independently with this and use
the same procedure.
Examples
========
An example of symmetric positive definite matrix:
.. plot::
:context: reset
:format: doctest
:include-source: True
>>> from sympy import Matrix, symbols
>>> from sympy.plotting import plot3d
>>> a, b = symbols('a b')
>>> x = Matrix([a, b])
>>> A = Matrix([[1, 0], [0, 1]])
>>> A.is_positive_definite
True
>>> A.is_positive_semidefinite
True
>>> p = plot3d((x.T*A*x)[0, 0], (a, -1, 1), (b, -1, 1))
An example of symmetric positive semidefinite matrix:
.. plot::
:context: close-figs
:format: doctest
:include-source: True
>>> A = Matrix([[1, -1], [-1, 1]])
>>> A.is_positive_definite
False
>>> A.is_positive_semidefinite
True
>>> p = plot3d((x.T*A*x)[0, 0], (a, -1, 1), (b, -1, 1))
An example of symmetric negative definite matrix:
.. plot::
:context: close-figs
:format: doctest
:include-source: True
>>> A = Matrix([[-1, 0], [0, -1]])
>>> A.is_negative_definite
True
>>> A.is_negative_semidefinite
True
>>> A.is_indefinite
False
>>> p = plot3d((x.T*A*x)[0, 0], (a, -1, 1), (b, -1, 1))
An example of symmetric indefinite matrix:
.. plot::
:context: close-figs
:format: doctest
:include-source: True
>>> A = Matrix([[1, 2], [2, -1]])
>>> A.is_indefinite
True
>>> p = plot3d((x.T*A*x)[0, 0], (a, -1, 1), (b, -1, 1))
An example of non-symmetric positive definite matrix.
.. plot::
:context: close-figs
:format: doctest
:include-source: True
>>> A = Matrix([[1, 2], [-2, 1]])
>>> A.is_positive_definite
True
>>> A.is_positive_semidefinite
True
>>> p = plot3d((x.T*A*x)[0, 0], (a, -1, 1), (b, -1, 1))
Notes
=====
Although some people trivialize the definition of positive definite
matrices only for symmetric or hermitian matrices, this restriction
is not correct because it does not classify all instances of
positive definite matrices from the definition $x^T A x > 0$ or
$\text{re}(x^H A x) > 0$.
For instance, ``Matrix([[1, 2], [-2, 1]])`` presented in
the example above is an example of real positive definite matrix
that is not symmetric.
However, since the following formula holds true;
.. math::
\text{re}(x^H A x) > 0 \iff
\text{re}(x^H \frac{A + A^H}{2} x) > 0
We can classify all positive definite matrices that may or may not
be symmetric or hermitian by transforming the matrix to
$\frac{A + A^T}{2}$ or $\frac{A + A^H}{2}$
(which is guaranteed to be always real symmetric or complex
hermitian) and we can defer most of the studies to symmetric or
hermitian positive definite matrices.
But it is a different problem for the existance of Cholesky
decomposition. Because even though a non symmetric or a non
hermitian matrix can be positive definite, Cholesky or LDL
decomposition does not exist because the decompositions require the
matrix to be symmetric or hermitian.
References
==========
.. [1] https://en.wikipedia.org/wiki/Definiteness_of_a_matrix#Eigenvalues
.. [2] http://mathworld.wolfram.com/PositiveDefiniteMatrix.html
.. [3] Johnson, C. R. "Positive Definite Matrices." Amer.
Math. Monthly 77, 259-264 1970.
"""
_is_positive_definite.__doc__ = _doc_positive_definite
_is_positive_semidefinite.__doc__ = _doc_positive_definite
_is_negative_definite.__doc__ = _doc_positive_definite
_is_negative_semidefinite.__doc__ = _doc_positive_definite
_is_indefinite.__doc__ = _doc_positive_definite
def _jordan_form(M, calc_transform=True, *, chop=False):
"""Return $(P, J)$ where $J$ is a Jordan block
matrix and $P$ is a matrix such that $M = P J P^{-1}$
Parameters
==========
calc_transform : bool
If ``False``, then only $J$ is returned.
chop : bool
All matrices are converted to exact types when computing
eigenvalues and eigenvectors. As a result, there may be
approximation errors. If ``chop==True``, these errors
will be truncated.
Examples
========
>>> from sympy.matrices import Matrix
>>> M = Matrix([[ 6, 5, -2, -3], [-3, -1, 3, 3], [ 2, 1, -2, -3], [-1, 1, 5, 5]])
>>> P, J = M.jordan_form()
>>> J
Matrix([
[2, 1, 0, 0],
[0, 2, 0, 0],
[0, 0, 2, 1],
[0, 0, 0, 2]])
See Also
========
jordan_block
"""
if not M.is_square:
raise NonSquareMatrixError("Only square matrices have Jordan forms")
mat = M
has_floats = M.has(Float)
if has_floats:
try:
max_prec = max(term._prec for term in M.values() if isinstance(term, Float))
except ValueError:
# if no term in the matrix is explicitly a Float calling max()
# will throw a error so setting max_prec to default value of 53
max_prec = 53
# setting minimum max_dps to 15 to prevent loss of precision in
# matrix containing non evaluated expressions
max_dps = max(prec_to_dps(max_prec), 15)
def restore_floats(*args):
"""If ``has_floats`` is `True`, cast all ``args`` as
matrices of floats."""
if has_floats:
args = [m.evalf(n=max_dps, chop=chop) for m in args]
if len(args) == 1:
return args[0]
return args
# cache calculations for some speedup
mat_cache = {}
def eig_mat(val, pow):
"""Cache computations of ``(M - val*I)**pow`` for quick
retrieval"""
if (val, pow) in mat_cache:
return mat_cache[(val, pow)]
if (val, pow - 1) in mat_cache:
mat_cache[(val, pow)] = mat_cache[(val, pow - 1)].multiply(
mat_cache[(val, 1)], dotprodsimp=None)
else:
mat_cache[(val, pow)] = (mat - val*M.eye(M.rows)).pow(pow)
return mat_cache[(val, pow)]
# helper functions
def nullity_chain(val, algebraic_multiplicity):
"""Calculate the sequence [0, nullity(E), nullity(E**2), ...]
until it is constant where ``E = M - val*I``"""
# mat.rank() is faster than computing the null space,
# so use the rank-nullity theorem
cols = M.cols
ret = [0]
nullity = cols - eig_mat(val, 1).rank()
i = 2
while nullity != ret[-1]:
ret.append(nullity)
if nullity == algebraic_multiplicity:
break
nullity = cols - eig_mat(val, i).rank()
i += 1
# Due to issues like #7146 and #15872, SymPy sometimes
# gives the wrong rank. In this case, raise an error
# instead of returning an incorrect matrix
if nullity < ret[-1] or nullity > algebraic_multiplicity:
raise MatrixError(
"SymPy had encountered an inconsistent "
"result while computing Jordan block: "
"{}".format(M))
return ret
def blocks_from_nullity_chain(d):
"""Return a list of the size of each Jordan block.
If d_n is the nullity of E**n, then the number
of Jordan blocks of size n is
2*d_n - d_(n-1) - d_(n+1)"""
# d[0] is always the number of columns, so skip past it
mid = [2*d[n] - d[n - 1] - d[n + 1] for n in range(1, len(d) - 1)]
# d is assumed to plateau with "d[ len(d) ] == d[-1]", so
# 2*d_n - d_(n-1) - d_(n+1) == d_n - d_(n-1)
end = [d[-1] - d[-2]] if len(d) > 1 else [d[0]]
return mid + end
def pick_vec(small_basis, big_basis):
"""Picks a vector from big_basis that isn't in
the subspace spanned by small_basis"""
if len(small_basis) == 0:
return big_basis[0]
for v in big_basis:
_, pivots = M.hstack(*(small_basis + [v])).echelon_form(
with_pivots=True)
if pivots[-1] == len(small_basis):
return v
# roots doesn't like Floats, so replace them with Rationals
if has_floats:
mat = mat.applyfunc(lambda x: nsimplify(x, rational=True))
# first calculate the jordan block structure
eigs = mat.eigenvals()
# Make sure that we have all roots in radical form
for x in eigs:
if x.has(CRootOf):
raise MatrixError(
"Jordan normal form is not implemented if the matrix have "
"eigenvalues in CRootOf form")
# most matrices have distinct eigenvalues
# and so are diagonalizable. In this case, don't
# do extra work!
if len(eigs.keys()) == mat.cols:
blocks = list(sorted(eigs.keys(), key=default_sort_key))
jordan_mat = mat.diag(*blocks)
if not calc_transform:
return restore_floats(jordan_mat)
jordan_basis = [eig_mat(eig, 1).nullspace()[0]
for eig in blocks]
basis_mat = mat.hstack(*jordan_basis)
return restore_floats(basis_mat, jordan_mat)
block_structure = []
for eig in sorted(eigs.keys(), key=default_sort_key):
algebraic_multiplicity = eigs[eig]
chain = nullity_chain(eig, algebraic_multiplicity)
block_sizes = blocks_from_nullity_chain(chain)
# if block_sizes = = [a, b, c, ...], then the number of
# Jordan blocks of size 1 is a, of size 2 is b, etc.
# create an array that has (eig, block_size) with one
# entry for each block
size_nums = [(i+1, num) for i, num in enumerate(block_sizes)]
# we expect larger Jordan blocks to come earlier
size_nums.reverse()
block_structure.extend(
(eig, size) for size, num in size_nums for _ in range(num))
jordan_form_size = sum(size for eig, size in block_structure)
if jordan_form_size != M.rows:
raise MatrixError(
"SymPy had encountered an inconsistent result while "
"computing Jordan block. : {}".format(M))
blocks = (mat.jordan_block(size=size, eigenvalue=eig) for eig, size in block_structure)
jordan_mat = mat.diag(*blocks)
if not calc_transform:
return restore_floats(jordan_mat)
# For each generalized eigenspace, calculate a basis.
# We start by looking for a vector in null( (A - eig*I)**n )
# which isn't in null( (A - eig*I)**(n-1) ) where n is
# the size of the Jordan block
#
# Ideally we'd just loop through block_structure and
# compute each generalized eigenspace. However, this
# causes a lot of unneeded computation. Instead, we
# go through the eigenvalues separately, since we know
# their generalized eigenspaces must have bases that
# are linearly independent.
jordan_basis = []
for eig in sorted(eigs.keys(), key=default_sort_key):
eig_basis = []
for block_eig, size in block_structure:
if block_eig != eig:
continue
null_big = (eig_mat(eig, size)).nullspace()
null_small = (eig_mat(eig, size - 1)).nullspace()
# we want to pick something that is in the big basis
# and not the small, but also something that is independent
# of any other generalized eigenvectors from a different
# generalized eigenspace sharing the same eigenvalue.
vec = pick_vec(null_small + eig_basis, null_big)
new_vecs = [eig_mat(eig, i).multiply(vec, dotprodsimp=None)
for i in range(size)]
eig_basis.extend(new_vecs)
jordan_basis.extend(reversed(new_vecs))
basis_mat = mat.hstack(*jordan_basis)
return restore_floats(basis_mat, jordan_mat)
def _left_eigenvects(M, **flags):
"""Returns left eigenvectors and eigenvalues.
This function returns the list of triples (eigenval, multiplicity,
basis) for the left eigenvectors. Options are the same as for
eigenvects(), i.e. the ``**flags`` arguments gets passed directly to
eigenvects().
Examples
========
>>> from sympy.matrices import Matrix
>>> M = Matrix([[0, 1, 1], [1, 0, 0], [1, 1, 1]])
>>> M.eigenvects()
[(-1, 1, [Matrix([
[-1],
[ 1],
[ 0]])]), (0, 1, [Matrix([
[ 0],
[-1],
[ 1]])]), (2, 1, [Matrix([
[2/3],
[1/3],
[ 1]])])]
>>> M.left_eigenvects()
[(-1, 1, [Matrix([[-2, 1, 1]])]), (0, 1, [Matrix([[-1, -1, 1]])]), (2,
1, [Matrix([[1, 1, 1]])])]
"""
eigs = M.transpose().eigenvects(**flags)
return [(val, mult, [l.transpose() for l in basis]) for val, mult, basis in eigs]
def _singular_values(M):
"""Compute the singular values of a Matrix
Examples
========
>>> from sympy import Matrix, Symbol
>>> x = Symbol('x', real=True)
>>> M = Matrix([[0, 1, 0], [0, x, 0], [-1, 0, 0]])
>>> M.singular_values()
[sqrt(x**2 + 1), 1, 0]
See Also
========
condition_number
"""
if M.rows >= M.cols:
valmultpairs = M.H.multiply(M).eigenvals()
else:
valmultpairs = M.multiply(M.H).eigenvals()
# Expands result from eigenvals into a simple list
vals = []
for k, v in valmultpairs.items():
vals += [sqrt(k)] * v # dangerous! same k in several spots!
# Pad with zeros if singular values are computed in reverse way,
# to give consistent format.
if len(vals) < M.cols:
vals += [M.zero] * (M.cols - len(vals))
# sort them in descending order
vals.sort(reverse=True, key=default_sort_key)
return vals
|
dd6c4113ef4540ca3a106ec658f7d96953218191a891ae185f77faf31563912b | from collections import defaultdict
from operator import index as index_
from sympy.core.compatibility import is_sequence
from sympy.core.expr import Expr
from sympy.core.kind import NumberKind, UndefinedKind
from sympy.core.numbers import Integer, Rational
from sympy.core.sympify import _sympify, SympifyError
from sympy.core.singleton import S
from sympy.polys.domains import ZZ, QQ, EXRAW
from sympy.polys.matrices import DomainMatrix
from sympy.utilities.misc import filldedent
from sympy.utilities.exceptions import SymPyDeprecationWarning
from .common import classof
from .matrices import MatrixBase, MatrixKind, ShapeError
class RepMatrix(MatrixBase):
"""Matrix implementation based on DomainMatrix as an internal representation.
The RepMatrix class is a superclass for Matrix, ImmutableMatrix,
SparseMatrix and ImmutableSparseMatrix which are the main usable matrix
classes in SymPy. Most methods on this class are simply forwarded to
DomainMatrix.
"""
#
# MatrixBase is the common superclass for all of the usable explicit matrix
# classes in SymPy. The idea is that MatrixBase is an abstract class though
# and that subclasses will implement the lower-level methods.
#
# RepMatrix is a subclass of MatrixBase that uses DomainMatrix as an
# internal representation and delegates lower-level methods to
# DomainMatrix. All of SymPy's standard explicit matrix classes subclass
# RepMatrix and so use DomainMatrix internally.
#
# A RepMatrix uses an internal DomainMatrix with the domain set to ZZ, QQ
# or EXRAW. The EXRAW domain is equivalent to the previous implementation
# of Matrix that used Expr for the elements. The ZZ and QQ domains are used
# when applicable just because they are compatible with the previous
# implementation but are much more efficient. Other domains such as QQ[x]
# are not used because they differ from Expr in some way (e.g. automatic
# expansion of powers and products).
#
def __eq__(self, other):
# Skip sympify for mutable matrices...
if not isinstance(other, RepMatrix):
try:
other = _sympify(other)
except SympifyError:
return NotImplemented
if not isinstance(other, RepMatrix):
return NotImplemented
return self._rep.unify_eq(other._rep)
@classmethod
def _unify_element_sympy(cls, rep, element):
domain = rep.domain
element = _sympify(element)
if domain != EXRAW:
# The domain can only be ZZ, QQ or EXRAW
if element.is_Integer:
new_domain = domain
elif element.is_Rational:
new_domain = QQ
else:
new_domain = EXRAW
# XXX: This converts the domain for all elements in the matrix
# which can be slow. This happens e.g. if __setitem__ changes one
# element to something that does not fit in the domain
if new_domain != domain:
rep = rep.convert_to(new_domain)
domain = new_domain
if domain != EXRAW:
element = new_domain.from_sympy(element)
if domain == EXRAW and not isinstance(element, Expr):
SymPyDeprecationWarning(
feature="non-Expr objects in a Matrix",
useinstead="list of lists, TableForm or some other data structure",
issue=21497,
deprecated_since_version="1.9"
).warn()
return rep, element
@classmethod
def _dod_to_DomainMatrix(cls, rows, cols, dod, types):
if not all(issubclass(typ, Expr) for typ in types):
SymPyDeprecationWarning(
feature="non-Expr objects in a Matrix",
useinstead="list of lists, TableForm or some other data structure",
issue=21497,
deprecated_since_version="1.9"
).warn()
rep = DomainMatrix(dod, (rows, cols), EXRAW)
if all(issubclass(typ, Rational) for typ in types):
if all(issubclass(typ, Integer) for typ in types):
rep = rep.convert_to(ZZ)
else:
rep = rep.convert_to(QQ)
return rep
@classmethod
def _flat_list_to_DomainMatrix(cls, rows, cols, flat_list):
elements_dod = defaultdict(dict)
for n, element in enumerate(flat_list):
if element != 0:
i, j = divmod(n, cols)
elements_dod[i][j] = element
types = set(map(type, flat_list))
rep = cls._dod_to_DomainMatrix(rows, cols, elements_dod, types)
return rep
@classmethod
def _smat_to_DomainMatrix(cls, rows, cols, smat):
elements_dod = defaultdict(dict)
for (i, j), element in smat.items():
if element != 0:
elements_dod[i][j] = element
types = set(map(type, smat.values()))
rep = cls._dod_to_DomainMatrix(rows, cols, elements_dod, types)
return rep
def flat(self):
return self._rep.to_sympy().to_list_flat()
def _eval_tolist(self):
return self._rep.to_sympy().to_list()
def _eval_todok(self):
return self._rep.to_sympy().to_dok()
def _eval_values(self):
return list(self.todok().values())
def copy(self):
return self._fromrep(self._rep.copy())
@property
def kind(self):
domain = self._rep.domain
if domain in (ZZ, QQ):
element_kind = NumberKind
elif domain == EXRAW:
kinds = set(e.kind for e in self.values())
if len(kinds) == 1:
[element_kind] = kinds
else:
element_kind = UndefinedKind
else: # pragma: no cover
raise RuntimeError("Domain should only be ZZ, QQ or EXRAW")
return MatrixKind(element_kind)
def _eval_has(self, *patterns):
# if the matrix has any zeros, see if S.Zero
# has the pattern. If _smat is full length,
# the matrix has no zeros.
zhas = False
dok = self.todok()
if len(dok) != self.rows*self.cols:
zhas = S.Zero.has(*patterns)
return zhas or any(value.has(*patterns) for value in dok.values())
def _eval_is_Identity(self):
if not all(self[i, i] == 1 for i in range(self.rows)):
return False
return len(self.todok()) == self.rows
def _eval_is_symmetric(self, simpfunc):
diff = (self - self.T).applyfunc(simpfunc)
return len(diff.values()) == 0
def _eval_transpose(self):
"""Returns the transposed SparseMatrix of this SparseMatrix.
Examples
========
>>> from sympy.matrices import SparseMatrix
>>> a = SparseMatrix(((1, 2), (3, 4)))
>>> a
Matrix([
[1, 2],
[3, 4]])
>>> a.T
Matrix([
[1, 3],
[2, 4]])
"""
return self._fromrep(self._rep.transpose())
def _eval_col_join(self, other):
return self._fromrep(self._rep.vstack(other._rep))
def _eval_row_join(self, other):
return self._fromrep(self._rep.hstack(other._rep))
def _eval_extract(self, rowsList, colsList):
return self._fromrep(self._rep.extract(rowsList, colsList))
def __getitem__(self, key):
return _getitem_RepMatrix(self, key)
@classmethod
def _eval_zeros(cls, rows, cols):
rep = DomainMatrix.zeros((rows, cols), ZZ)
return cls._fromrep(rep)
@classmethod
def _eval_eye(cls, rows, cols):
rep = DomainMatrix.eye((rows, cols), ZZ)
return cls._fromrep(rep)
def _eval_add(self, other):
return classof(self, other)._fromrep(self._rep + other._rep)
def _eval_matrix_mul(self, other):
return classof(self, other)._fromrep(self._rep * other._rep)
def _eval_matrix_mul_elementwise(self, other):
rep = self._rep.mul_elementwise(other._rep)
return classof(self, other)._fromrep(rep)
def _eval_scalar_mul(self, other):
rep, other = self._unify_element_sympy(self._rep, other)
return self._fromrep(rep.scalarmul(other))
def _eval_scalar_rmul(self, other):
rep, other = self._unify_element_sympy(self._rep, other)
return self._fromrep(rep.rscalarmul(other))
def _eval_Abs(self):
return self._fromrep(self._rep.applyfunc(abs))
def _eval_conjugate(self):
rep = self._rep
domain = rep.domain
if domain in (ZZ, QQ):
return self.copy()
else:
return self._fromrep(rep.applyfunc(lambda e: e.conjugate()))
def equals(self, other, failing_expression=False):
"""Applies ``equals`` to corresponding elements of the matrices,
trying to prove that the elements are equivalent, returning True
if they are, False if any pair is not, and None (or the first
failing expression if failing_expression is True) if it cannot
be decided if the expressions are equivalent or not. This is, in
general, an expensive operation.
Examples
========
>>> from sympy.matrices import Matrix
>>> from sympy.abc import x
>>> A = Matrix([x*(x - 1), 0])
>>> B = Matrix([x**2 - x, 0])
>>> A == B
False
>>> A.simplify() == B.simplify()
True
>>> A.equals(B)
True
>>> A.equals(2)
False
See Also
========
sympy.core.expr.Expr.equals
"""
if self.shape != getattr(other, 'shape', None):
return False
rv = True
for i in range(self.rows):
for j in range(self.cols):
ans = self[i, j].equals(other[i, j], failing_expression)
if ans is False:
return False
elif ans is not True and rv is True:
rv = ans
return rv
class MutableRepMatrix(RepMatrix):
"""Mutable matrix based on DomainMatrix as the internal representation"""
#
# MutableRepMatrix is a subclass of RepMatrix that adds/overrides methods
# to make the instances mutable. MutableRepMatrix is a superclass for both
# MutableDenseMatrix and MutableSparseMatrix.
#
__hash__ = None
is_zero = False
def __new__(cls, *args, **kwargs):
return cls._new(*args, **kwargs)
@classmethod
def _new(cls, *args, copy=True, **kwargs):
if copy is False:
# The input was rows, cols, [list].
# It should be used directly without creating a copy.
if len(args) != 3:
raise TypeError("'copy=False' requires a matrix be initialized as rows,cols,[list]")
rows, cols, flat_list = args
else:
rows, cols, flat_list = cls._handle_creation_inputs(*args, **kwargs)
flat_list = list(flat_list) # create a shallow copy
rep = cls._flat_list_to_DomainMatrix(rows, cols, flat_list)
return cls._fromrep(rep)
@classmethod
def _fromrep(cls, rep):
obj = super().__new__(cls)
obj.rows, obj.cols = rep.shape
obj._rep = rep
return obj
def copy(self):
return self._fromrep(self._rep.copy())
def as_mutable(self):
return self.copy()
def __setitem__(self, key, value):
"""
Examples
========
>>> from sympy import Matrix, I, zeros, ones
>>> m = Matrix(((1, 2+I), (3, 4)))
>>> m
Matrix([
[1, 2 + I],
[3, 4]])
>>> m[1, 0] = 9
>>> m
Matrix([
[1, 2 + I],
[9, 4]])
>>> m[1, 0] = [[0, 1]]
To replace row r you assign to position r*m where m
is the number of columns:
>>> M = zeros(4)
>>> m = M.cols
>>> M[3*m] = ones(1, m)*2; M
Matrix([
[0, 0, 0, 0],
[0, 0, 0, 0],
[0, 0, 0, 0],
[2, 2, 2, 2]])
And to replace column c you can assign to position c:
>>> M[2] = ones(m, 1)*4; M
Matrix([
[0, 0, 4, 0],
[0, 0, 4, 0],
[0, 0, 4, 0],
[2, 2, 4, 2]])
"""
rv = self._setitem(key, value)
if rv is not None:
i, j, value = rv
self._rep, value = self._unify_element_sympy(self._rep, value)
self._rep.rep.setitem(i, j, value)
def _eval_col_del(self, col):
self._rep = DomainMatrix.hstack(self._rep[:,:col], self._rep[:,col+1:])
self.cols -= 1
def _eval_row_del(self, row):
self._rep = DomainMatrix.vstack(self._rep[:row,:], self._rep[row+1:, :])
self.rows -= 1
def _eval_col_insert(self, col, other):
other = self._new(other)
return self.hstack(self[:,:col], other, self[:,col:])
def _eval_row_insert(self, row, other):
other = self._new(other)
return self.vstack(self[:row,:], other, self[row:,:])
def col_op(self, j, f):
"""In-place operation on col j using two-arg functor whose args are
interpreted as (self[i, j], i).
Examples
========
>>> from sympy.matrices import eye
>>> M = eye(3)
>>> M.col_op(1, lambda v, i: v + 2*M[i, 0]); M
Matrix([
[1, 2, 0],
[0, 1, 0],
[0, 0, 1]])
See Also
========
col
row_op
"""
for i in range(self.rows):
self[i, j] = f(self[i, j], i)
def col_swap(self, i, j):
"""Swap the two given columns of the matrix in-place.
Examples
========
>>> from sympy.matrices import Matrix
>>> M = Matrix([[1, 0], [1, 0]])
>>> M
Matrix([
[1, 0],
[1, 0]])
>>> M.col_swap(0, 1)
>>> M
Matrix([
[0, 1],
[0, 1]])
See Also
========
col
row_swap
"""
for k in range(0, self.rows):
self[k, i], self[k, j] = self[k, j], self[k, i]
def row_op(self, i, f):
"""In-place operation on row ``i`` using two-arg functor whose args are
interpreted as ``(self[i, j], j)``.
Examples
========
>>> from sympy.matrices import eye
>>> M = eye(3)
>>> M.row_op(1, lambda v, j: v + 2*M[0, j]); M
Matrix([
[1, 0, 0],
[2, 1, 0],
[0, 0, 1]])
See Also
========
row
zip_row_op
col_op
"""
for j in range(self.cols):
self[i, j] = f(self[i, j], j)
def row_swap(self, i, j):
"""Swap the two given rows of the matrix in-place.
Examples
========
>>> from sympy.matrices import Matrix
>>> M = Matrix([[0, 1], [1, 0]])
>>> M
Matrix([
[0, 1],
[1, 0]])
>>> M.row_swap(0, 1)
>>> M
Matrix([
[1, 0],
[0, 1]])
See Also
========
row
col_swap
"""
for k in range(0, self.cols):
self[i, k], self[j, k] = self[j, k], self[i, k]
def zip_row_op(self, i, k, f):
"""In-place operation on row ``i`` using two-arg functor whose args are
interpreted as ``(self[i, j], self[k, j])``.
Examples
========
>>> from sympy.matrices import eye
>>> M = eye(3)
>>> M.zip_row_op(1, 0, lambda v, u: v + 2*u); M
Matrix([
[1, 0, 0],
[2, 1, 0],
[0, 0, 1]])
See Also
========
row
row_op
col_op
"""
for j in range(self.cols):
self[i, j] = f(self[i, j], self[k, j])
def copyin_list(self, key, value):
"""Copy in elements from a list.
Parameters
==========
key : slice
The section of this matrix to replace.
value : iterable
The iterable to copy values from.
Examples
========
>>> from sympy.matrices import eye
>>> I = eye(3)
>>> I[:2, 0] = [1, 2] # col
>>> I
Matrix([
[1, 0, 0],
[2, 1, 0],
[0, 0, 1]])
>>> I[1, :2] = [[3, 4]]
>>> I
Matrix([
[1, 0, 0],
[3, 4, 0],
[0, 0, 1]])
See Also
========
copyin_matrix
"""
if not is_sequence(value):
raise TypeError("`value` must be an ordered iterable, not %s." % type(value))
return self.copyin_matrix(key, type(self)(value))
def copyin_matrix(self, key, value):
"""Copy in values from a matrix into the given bounds.
Parameters
==========
key : slice
The section of this matrix to replace.
value : Matrix
The matrix to copy values from.
Examples
========
>>> from sympy.matrices import Matrix, eye
>>> M = Matrix([[0, 1], [2, 3], [4, 5]])
>>> I = eye(3)
>>> I[:3, :2] = M
>>> I
Matrix([
[0, 1, 0],
[2, 3, 0],
[4, 5, 1]])
>>> I[0, 1] = M
>>> I
Matrix([
[0, 0, 1],
[2, 2, 3],
[4, 4, 5]])
See Also
========
copyin_list
"""
rlo, rhi, clo, chi = self.key2bounds(key)
shape = value.shape
dr, dc = rhi - rlo, chi - clo
if shape != (dr, dc):
raise ShapeError(filldedent("The Matrix `value` doesn't have the "
"same dimensions "
"as the in sub-Matrix given by `key`."))
for i in range(value.rows):
for j in range(value.cols):
self[i + rlo, j + clo] = value[i, j]
def fill(self, value):
"""Fill self with the given value.
Notes
=====
Unless many values are going to be deleted (i.e. set to zero)
this will create a matrix that is slower than a dense matrix in
operations.
Examples
========
>>> from sympy.matrices import SparseMatrix
>>> M = SparseMatrix.zeros(3); M
Matrix([
[0, 0, 0],
[0, 0, 0],
[0, 0, 0]])
>>> M.fill(1); M
Matrix([
[1, 1, 1],
[1, 1, 1],
[1, 1, 1]])
See Also
========
zeros
ones
"""
value = _sympify(value)
if not value:
self._rep = DomainMatrix.zeros(self.shape, EXRAW)
else:
elements_dod = {i: {j: value for j in range(self.cols)} for i in range(self.rows)}
self._rep = DomainMatrix(elements_dod, self.shape, EXRAW)
def _getitem_RepMatrix(self, key):
"""Return portion of self defined by key. If the key involves a slice
then a list will be returned (if key is a single slice) or a matrix
(if key was a tuple involving a slice).
Examples
========
>>> from sympy import Matrix, I
>>> m = Matrix([
... [1, 2 + I],
... [3, 4 ]])
If the key is a tuple that doesn't involve a slice then that element
is returned:
>>> m[1, 0]
3
When a tuple key involves a slice, a matrix is returned. Here, the
first column is selected (all rows, column 0):
>>> m[:, 0]
Matrix([
[1],
[3]])
If the slice is not a tuple then it selects from the underlying
list of elements that are arranged in row order and a list is
returned if a slice is involved:
>>> m[0]
1
>>> m[::2]
[1, 3]
"""
if isinstance(key, tuple):
i, j = key
try:
return self._rep.getitem_sympy(index_(i), index_(j))
except (TypeError, IndexError):
if (isinstance(i, Expr) and not i.is_number) or (isinstance(j, Expr) and not j.is_number):
if ((j < 0) is True) or ((j >= self.shape[1]) is True) or\
((i < 0) is True) or ((i >= self.shape[0]) is True):
raise ValueError("index out of boundary")
from sympy.matrices.expressions.matexpr import MatrixElement
return MatrixElement(self, i, j)
if isinstance(i, slice):
i = range(self.rows)[i]
elif is_sequence(i):
pass
else:
i = [i]
if isinstance(j, slice):
j = range(self.cols)[j]
elif is_sequence(j):
pass
else:
j = [j]
return self.extract(i, j)
else:
# Index/slice like a flattened list
rows, cols = self.shape
# Raise the appropriate exception:
if not rows * cols:
return [][key]
rep = self._rep.rep
domain = rep.domain
is_slice = isinstance(key, slice)
if is_slice:
values = [rep.getitem(*divmod(n, cols)) for n in range(rows * cols)[key]]
else:
values = [rep.getitem(*divmod(index_(key), cols))]
if domain != EXRAW:
to_sympy = domain.to_sympy
values = [to_sympy(val) for val in values]
if is_slice:
return values
else:
return values[0]
|
38d51964819b41492871953c73e831b581d62aa322f25abb01be854c23b4de94 | from sympy.core.compatibility import as_int
from sympy.utilities.iterables import is_sequence
from sympy.utilities.misc import filldedent
from .sparse import MutableSparseMatrix
def _doktocsr(dok):
"""Converts a sparse matrix to Compressed Sparse Row (CSR) format.
Parameters
==========
A : contains non-zero elements sorted by key (row, column)
JA : JA[i] is the column corresponding to A[i]
IA : IA[i] contains the index in A for the first non-zero element
of row[i]. Thus IA[i+1] - IA[i] gives number of non-zero
elements row[i]. The length of IA is always 1 more than the
number of rows in the matrix.
Examples
========
>>> from sympy.matrices.sparsetools import _doktocsr
>>> from sympy import SparseMatrix, diag
>>> m = SparseMatrix(diag(1, 2, 3))
>>> m[2, 0] = -1
>>> _doktocsr(m)
[[1, 2, -1, 3], [0, 1, 0, 2], [0, 1, 2, 4], [3, 3]]
"""
row, JA, A = [list(i) for i in zip(*dok.row_list())]
IA = [0]*((row[0] if row else 0) + 1)
for i, r in enumerate(row):
IA.extend([i]*(r - row[i - 1])) # if i = 0 nothing is extended
IA.extend([len(A)]*(dok.rows - len(IA) + 1))
shape = [dok.rows, dok.cols]
return [A, JA, IA, shape]
def _csrtodok(csr):
"""Converts a CSR representation to DOK representation.
Examples
========
>>> from sympy.matrices.sparsetools import _csrtodok
>>> _csrtodok([[5, 8, 3, 6], [0, 1, 2, 1], [0, 0, 2, 3, 4], [4, 3]])
Matrix([
[0, 0, 0],
[5, 8, 0],
[0, 0, 3],
[0, 6, 0]])
"""
smat = {}
A, JA, IA, shape = csr
for i in range(len(IA) - 1):
indices = slice(IA[i], IA[i + 1])
for l, m in zip(A[indices], JA[indices]):
smat[i, m] = l
return MutableSparseMatrix(*shape, smat)
def banded(*args, **kwargs):
"""Returns a SparseMatrix from the given dictionary describing
the diagonals of the matrix. The keys are positive for upper
diagonals and negative for those below the main diagonal. The
values may be:
* expressions or single-argument functions,
* lists or tuples of values,
* matrices
Unless dimensions are given, the size of the returned matrix will
be large enough to contain the largest non-zero value provided.
kwargs
======
rows : rows of the resulting matrix; computed if
not given.
cols : columns of the resulting matrix; computed if
not given.
Examples
========
>>> from sympy import banded, ones, Matrix
>>> from sympy.abc import x
If explicit values are given in tuples,
the matrix will autosize to contain all values, otherwise
a single value is filled onto the entire diagonal:
>>> banded({1: (1, 2, 3), -1: (4, 5, 6), 0: x})
Matrix([
[x, 1, 0, 0],
[4, x, 2, 0],
[0, 5, x, 3],
[0, 0, 6, x]])
A function accepting a single argument can be used to fill the
diagonal as a function of diagonal index (which starts at 0).
The size (or shape) of the matrix must be given to obtain more
than a 1x1 matrix:
>>> s = lambda d: (1 + d)**2
>>> banded(5, {0: s, 2: s, -2: 2})
Matrix([
[1, 0, 1, 0, 0],
[0, 4, 0, 4, 0],
[2, 0, 9, 0, 9],
[0, 2, 0, 16, 0],
[0, 0, 2, 0, 25]])
The diagonal of matrices placed on a diagonal will coincide
with the indicated diagonal:
>>> vert = Matrix([1, 2, 3])
>>> banded({0: vert}, cols=3)
Matrix([
[1, 0, 0],
[2, 1, 0],
[3, 2, 1],
[0, 3, 2],
[0, 0, 3]])
>>> banded(4, {0: ones(2)})
Matrix([
[1, 1, 0, 0],
[1, 1, 0, 0],
[0, 0, 1, 1],
[0, 0, 1, 1]])
Errors are raised if the designated size will not hold
all values an integral number of times. Here, the rows
are designated as odd (but an even number is required to
hold the off-diagonal 2x2 ones):
>>> banded({0: 2, 1: ones(2)}, rows=5)
Traceback (most recent call last):
...
ValueError:
sequence does not fit an integral number of times in the matrix
And here, an even number of rows is given...but the square
matrix has an even number of columns, too. As we saw
in the previous example, an odd number is required:
>>> banded(4, {0: 2, 1: ones(2)}) # trying to make 4x4 and cols must be odd
Traceback (most recent call last):
...
ValueError:
sequence does not fit an integral number of times in the matrix
A way around having to count rows is to enclosing matrix elements
in a tuple and indicate the desired number of them to the right:
>>> banded({0: 2, 2: (ones(2),)*3})
Matrix([
[2, 0, 1, 1, 0, 0, 0, 0],
[0, 2, 1, 1, 0, 0, 0, 0],
[0, 0, 2, 0, 1, 1, 0, 0],
[0, 0, 0, 2, 1, 1, 0, 0],
[0, 0, 0, 0, 2, 0, 1, 1],
[0, 0, 0, 0, 0, 2, 1, 1]])
An error will be raised if more than one value
is written to a given entry. Here, the ones overlap
with the main diagonal if they are placed on the
first diagonal:
>>> banded({0: (2,)*5, 1: (ones(2),)*3})
Traceback (most recent call last):
...
ValueError: collision at (1, 1)
By placing a 0 at the bottom left of the 2x2 matrix of
ones, the collision is avoided:
>>> u2 = Matrix([
... [1, 1],
... [0, 1]])
>>> banded({0: [2]*5, 1: [u2]*3})
Matrix([
[2, 1, 1, 0, 0, 0, 0],
[0, 2, 1, 0, 0, 0, 0],
[0, 0, 2, 1, 1, 0, 0],
[0, 0, 0, 2, 1, 0, 0],
[0, 0, 0, 0, 2, 1, 1],
[0, 0, 0, 0, 0, 0, 1]])
"""
from sympy import Dict, Dummy, SparseMatrix
try:
if len(args) not in (1, 2, 3):
raise TypeError
if not isinstance(args[-1], (dict, Dict)):
raise TypeError
if len(args) == 1:
rows = kwargs.get('rows', None)
cols = kwargs.get('cols', None)
if rows is not None:
rows = as_int(rows)
if cols is not None:
cols = as_int(cols)
elif len(args) == 2:
rows = cols = as_int(args[0])
else:
rows, cols = map(as_int, args[:2])
# fails with ValueError if any keys are not ints
_ = all(as_int(k) for k in args[-1])
except (ValueError, TypeError):
raise TypeError(filldedent(
'''unrecognized input to banded:
expecting [[row,] col,] {int: value}'''))
def rc(d):
# return row,col coord of diagonal start
r = -d if d < 0 else 0
c = 0 if r else d
return r, c
smat = {}
undone = []
tba = Dummy()
# first handle objects with size
for d, v in args[-1].items():
r, c = rc(d)
# note: only list and tuple are recognized since this
# will allow other Basic objects like Tuple
# into the matrix if so desired
if isinstance(v, (list, tuple)):
extra = 0
for i, vi in enumerate(v):
i += extra
if is_sequence(vi):
vi = SparseMatrix(vi)
smat[r + i, c + i] = vi
extra += min(vi.shape) - 1
else:
smat[r + i, c + i] = vi
elif is_sequence(v):
v = SparseMatrix(v)
rv, cv = v.shape
if rows and cols:
nr, xr = divmod(rows - r, rv)
nc, xc = divmod(cols - c, cv)
x = xr or xc
do = min(nr, nc)
elif rows:
do, x = divmod(rows - r, rv)
elif cols:
do, x = divmod(cols - c, cv)
else:
do = 1
x = 0
if x:
raise ValueError(filldedent('''
sequence does not fit an integral number of times
in the matrix'''))
j = min(v.shape)
for i in range(do):
smat[r, c] = v
r += j
c += j
elif v:
smat[r, c] = tba
undone.append((d, v))
s = SparseMatrix(None, smat) # to expand matrices
smat = s.todok()
# check for dim errors here
if rows is not None and rows < s.rows:
raise ValueError('Designated rows %s < needed %s' % (rows, s.rows))
if cols is not None and cols < s.cols:
raise ValueError('Designated cols %s < needed %s' % (cols, s.cols))
if rows is cols is None:
rows = s.rows
cols = s.cols
elif rows is not None and cols is None:
cols = max(rows, s.cols)
elif cols is not None and rows is None:
rows = max(cols, s.rows)
def update(i, j, v):
# update smat and make sure there are
# no collisions
if v:
if (i, j) in smat and smat[i, j] not in (tba, v):
raise ValueError('collision at %s' % ((i, j),))
smat[i, j] = v
if undone:
for d, vi in undone:
r, c = rc(d)
v = vi if callable(vi) else lambda _: vi
i = 0
while r + i < rows and c + i < cols:
update(r + i, c + i, v(i))
i += 1
return SparseMatrix(rows, cols, smat)
|
dc64c2e1829b62e57f5216c9378eb089e2c43460f2462e855115919ddfaef97c | from sympy import (S, Symbol, Interval, binomial, nan, exp, Or,
symbols, Eq, cos, And, Tuple, integrate, oo, sin, Sum, Basic, Indexed,
DiracDelta, Lambda, log, pi, FallingFactorial, Rational, Matrix)
from sympy.stats import (Die, Normal, Exponential, FiniteRV, P, E, H, variance,
density, given, independent, dependent, where, pspace, GaussianUnitaryEnsemble,
random_symbols, sample, Geometric, factorial_moment, Binomial, Hypergeometric,
DiscreteUniform, Poisson, characteristic_function, moment_generating_function,
BernoulliProcess, Variance, Expectation, Probability, Covariance, covariance)
from sympy.stats.rv import (IndependentProductPSpace, rs_swap, Density, NamedArgsMixin,
RandomSymbol, sample_iter, PSpace, is_random, RandomIndexedSymbol, RandomMatrixSymbol)
from sympy.testing.pytest import raises, skip, XFAIL
from sympy.external import import_module
from sympy.core.numbers import comp
from sympy.stats.frv_types import BernoulliDistribution
from sympy.core.symbol import Dummy
from sympy.functions.elementary.piecewise import Piecewise
def test_where():
X, Y = Die('X'), Die('Y')
Z = Normal('Z', 0, 1)
assert where(Z**2 <= 1).set == Interval(-1, 1)
assert where(Z**2 <= 1).as_boolean() == Interval(-1, 1).as_relational(Z.symbol)
assert where(And(X > Y, Y > 4)).as_boolean() == And(
Eq(X.symbol, 6), Eq(Y.symbol, 5))
assert len(where(X < 3).set) == 2
assert 1 in where(X < 3).set
X, Y = Normal('X', 0, 1), Normal('Y', 0, 1)
assert where(And(X**2 <= 1, X >= 0)).set == Interval(0, 1)
XX = given(X, And(X**2 <= 1, X >= 0))
assert XX.pspace.domain.set == Interval(0, 1)
assert XX.pspace.domain.as_boolean() == \
And(0 <= X.symbol, X.symbol**2 <= 1, -oo < X.symbol, X.symbol < oo)
with raises(TypeError):
XX = given(X, X + 3)
def test_random_symbols():
X, Y = Normal('X', 0, 1), Normal('Y', 0, 1)
assert set(random_symbols(2*X + 1)) == {X}
assert set(random_symbols(2*X + Y)) == {X, Y}
assert set(random_symbols(2*X + Y.symbol)) == {X}
assert set(random_symbols(2)) == set()
def test_characteristic_function():
# Imports I from sympy
from sympy import I
X = Normal('X',0,1)
Y = DiscreteUniform('Y', [1,2,7])
Z = Poisson('Z', 2)
t = symbols('_t')
P = Lambda(t, exp(-t**2/2))
Q = Lambda(t, exp(7*t*I)/3 + exp(2*t*I)/3 + exp(t*I)/3)
R = Lambda(t, exp(2 * exp(t*I) - 2))
assert characteristic_function(X).dummy_eq(P)
assert characteristic_function(Y).dummy_eq(Q)
assert characteristic_function(Z).dummy_eq(R)
def test_moment_generating_function():
X = Normal('X',0,1)
Y = DiscreteUniform('Y', [1,2,7])
Z = Poisson('Z', 2)
t = symbols('_t')
P = Lambda(t, exp(t**2/2))
Q = Lambda(t, (exp(7*t)/3 + exp(2*t)/3 + exp(t)/3))
R = Lambda(t, exp(2 * exp(t) - 2))
assert moment_generating_function(X).dummy_eq(P)
assert moment_generating_function(Y).dummy_eq(Q)
assert moment_generating_function(Z).dummy_eq(R)
def test_sample_iter():
X = Normal('X',0,1)
Y = DiscreteUniform('Y', [1, 2, 7])
Z = Poisson('Z', 2)
scipy = import_module('scipy')
if not scipy:
skip('Scipy is not installed. Abort tests')
expr = X**2 + 3
iterator = sample_iter(expr)
expr2 = Y**2 + 5*Y + 4
iterator2 = sample_iter(expr2)
expr3 = Z**3 + 4
iterator3 = sample_iter(expr3)
def is_iterator(obj):
if (
hasattr(obj, '__iter__') and
(hasattr(obj, 'next') or
hasattr(obj, '__next__')) and
callable(obj.__iter__) and
obj.__iter__() is obj
):
return True
else:
return False
assert is_iterator(iterator)
assert is_iterator(iterator2)
assert is_iterator(iterator3)
def test_pspace():
X, Y = Normal('X', 0, 1), Normal('Y', 0, 1)
x = Symbol('x')
raises(ValueError, lambda: pspace(5 + 3))
raises(ValueError, lambda: pspace(x < 1))
assert pspace(X) == X.pspace
assert pspace(2*X + 1) == X.pspace
assert pspace(2*X + Y) == IndependentProductPSpace(Y.pspace, X.pspace)
def test_rs_swap():
X = Normal('x', 0, 1)
Y = Exponential('y', 1)
XX = Normal('x', 0, 2)
YY = Normal('y', 0, 3)
expr = 2*X + Y
assert expr.subs(rs_swap((X, Y), (YY, XX))) == 2*XX + YY
def test_RandomSymbol():
X = Normal('x', 0, 1)
Y = Normal('x', 0, 2)
assert X.symbol == Y.symbol
assert X != Y
assert X.name == X.symbol.name
X = Normal('lambda', 0, 1) # make sure we can use protected terms
X = Normal('Lambda', 0, 1) # make sure we can use SymPy terms
def test_RandomSymbol_diff():
X = Normal('x', 0, 1)
assert (2*X).diff(X)
def test_random_symbol_no_pspace():
x = RandomSymbol(Symbol('x'))
assert x.pspace == PSpace()
def test_overlap():
X = Normal('x', 0, 1)
Y = Normal('x', 0, 2)
raises(ValueError, lambda: P(X > Y))
def test_IndependentProductPSpace():
X = Normal('X', 0, 1)
Y = Normal('Y', 0, 1)
px = X.pspace
py = Y.pspace
assert pspace(X + Y) == IndependentProductPSpace(px, py)
assert pspace(X + Y) == IndependentProductPSpace(py, px)
def test_E():
assert E(5) == 5
def test_H():
X = Normal('X', 0, 1)
D = Die('D', sides = 4)
G = Geometric('G', 0.5)
assert H(X, X > 0) == -log(2)/2 + S.Half + log(pi)/2
assert H(D, D > 2) == log(2)
assert comp(H(G).evalf().round(2), 1.39)
def test_Sample():
X = Die('X', 6)
Y = Normal('Y', 0, 1)
z = Symbol('z', integer=True)
scipy = import_module('scipy')
if not scipy:
skip('Scipy is not installed. Abort tests')
assert sample(X) in [1, 2, 3, 4, 5, 6]
assert isinstance(sample(X + Y), float)
assert P(X + Y > 0, Y < 0, numsamples=10).is_number
assert E(X + Y, numsamples=10).is_number
assert E(X**2 + Y, numsamples=10).is_number
assert E((X + Y)**2, numsamples=10).is_number
assert variance(X + Y, numsamples=10).is_number
raises(TypeError, lambda: P(Y > z, numsamples=5))
assert P(sin(Y) <= 1, numsamples=10) == 1
assert P(sin(Y) <= 1, cos(Y) < 1, numsamples=10) == 1
assert all(i in range(1, 7) for i in density(X, numsamples=10))
assert all(i in range(4, 7) for i in density(X, X>3, numsamples=10))
numpy = import_module('numpy')
if not numpy:
skip('Numpy is not installed. Abort tests')
#Test Issue #21563: Output of sample must be a float or array
assert isinstance(sample(X), numpy.int64)
assert isinstance(sample(Y), numpy.float64)
assert isinstance(sample(X, size=2), numpy.ndarray)
@XFAIL
def test_samplingE():
scipy = import_module('scipy')
if not scipy:
skip('Scipy is not installed. Abort tests')
Y = Normal('Y', 0, 1)
z = Symbol('z', integer=True)
assert E(Sum(1/z**Y, (z, 1, oo)), Y > 2, numsamples=3).is_number
def test_given():
X = Normal('X', 0, 1)
Y = Normal('Y', 0, 1)
A = given(X, True)
B = given(X, Y > 2)
assert X == A == B
def test_factorial_moment():
X = Poisson('X', 2)
Y = Binomial('Y', 2, S.Half)
Z = Hypergeometric('Z', 4, 2, 2)
assert factorial_moment(X, 2) == 4
assert factorial_moment(Y, 2) == S.Half
assert factorial_moment(Z, 2) == Rational(1, 3)
x, y, z, l = symbols('x y z l')
Y = Binomial('Y', 2, y)
Z = Hypergeometric('Z', 10, 2, 3)
assert factorial_moment(Y, l) == y**2*FallingFactorial(
2, l) + 2*y*(1 - y)*FallingFactorial(1, l) + (1 - y)**2*\
FallingFactorial(0, l)
assert factorial_moment(Z, l) == 7*FallingFactorial(0, l)/\
15 + 7*FallingFactorial(1, l)/15 + FallingFactorial(2, l)/15
def test_dependence():
X, Y = Die('X'), Die('Y')
assert independent(X, 2*Y)
assert not dependent(X, 2*Y)
X, Y = Normal('X', 0, 1), Normal('Y', 0, 1)
assert independent(X, Y)
assert dependent(X, 2*X)
# Create a dependency
XX, YY = given(Tuple(X, Y), Eq(X + Y, 3))
assert dependent(XX, YY)
def test_dependent_finite():
X, Y = Die('X'), Die('Y')
# Dependence testing requires symbolic conditions which currently break
# finite random variables
assert dependent(X, Y + X)
XX, YY = given(Tuple(X, Y), X + Y > 5) # Create a dependency
assert dependent(XX, YY)
def test_normality():
X, Y = Normal('X', 0, 1), Normal('Y', 0, 1)
x = Symbol('x', real=True, finite=True)
z = Symbol('z', real=True, finite=True)
dens = density(X - Y, Eq(X + Y, z))
assert integrate(dens(x), (x, -oo, oo)) == 1
def test_Density():
X = Die('X', 6)
d = Density(X)
assert d.doit() == density(X)
def test_NamedArgsMixin():
class Foo(Basic, NamedArgsMixin):
_argnames = 'foo', 'bar'
a = Foo(1, 2)
assert a.foo == 1
assert a.bar == 2
raises(AttributeError, lambda: a.baz)
class Bar(Basic, NamedArgsMixin):
pass
raises(AttributeError, lambda: Bar(1, 2).foo)
def test_density_constant():
assert density(3)(2) == 0
assert density(3)(3) == DiracDelta(0)
def test_real():
x = Normal('x', 0, 1)
assert x.is_real
def test_issue_10052():
X = Exponential('X', 3)
assert P(X < oo) == 1
assert P(X > oo) == 0
assert P(X < 2, X > oo) == 0
assert P(X < oo, X > oo) == 0
assert P(X < oo, X > 2) == 1
assert P(X < 3, X == 2) == 0
raises(ValueError, lambda: P(1))
raises(ValueError, lambda: P(X < 1, 2))
def test_issue_11934():
density = {0: .5, 1: .5}
X = FiniteRV('X', density)
assert E(X) == 0.5
assert P( X>= 2) == 0
def test_issue_8129():
X = Exponential('X', 4)
assert P(X >= X) == 1
assert P(X > X) == 0
assert P(X > X+1) == 0
def test_issue_12237():
X = Normal('X', 0, 1)
Y = Normal('Y', 0, 1)
U = P(X > 0, X)
V = P(Y < 0, X)
W = P(X + Y > 0, X)
assert W == P(X + Y > 0, X)
assert U == BernoulliDistribution(S.Half, S.Zero, S.One)
assert V == S.Half
def test_is_random():
X = Normal('X', 0, 1)
Y = Normal('Y', 0, 1)
a, b = symbols('a, b')
G = GaussianUnitaryEnsemble('U', 2)
B = BernoulliProcess('B', 0.9)
assert not is_random(a)
assert not is_random(a + b)
assert not is_random(a * b)
assert not is_random(Matrix([a**2, b**2]))
assert is_random(X)
assert is_random(X**2 + Y)
assert is_random(Y + b**2)
assert is_random(Y > 5)
assert is_random(B[3] < 1)
assert is_random(G)
assert is_random(X * Y * B[1])
assert is_random(Matrix([[X, B[2]], [G, Y]]))
assert is_random(Eq(X, 4))
def test_issue_12283():
x = symbols('x')
X = RandomSymbol(x)
Y = RandomSymbol('Y')
Z = RandomMatrixSymbol('Z', 2, 1)
W = RandomMatrixSymbol('W', 2, 1)
RI = RandomIndexedSymbol(Indexed('RI', 3))
assert pspace(Z) == PSpace()
assert pspace(RI) == PSpace()
assert pspace(X) == PSpace()
assert E(X) == Expectation(X)
assert P(Y > 3) == Probability(Y > 3)
assert variance(X) == Variance(X)
assert variance(RI) == Variance(RI)
assert covariance(X, Y) == Covariance(X, Y)
assert covariance(W, Z) == Covariance(W, Z)
def test_issue_6810():
X = Die('X', 6)
Y = Normal('Y', 0, 1)
assert P(Eq(X, 2)) == S(1)/6
assert P(Eq(Y, 0)) == 0
assert P(Or(X > 2, X < 3)) == 1
assert P(And(X > 3, X > 2)) == S(1)/2
def test_issue_20286():
n, p = symbols('n p')
B = Binomial('B', n, p)
k = Dummy('k', integer = True)
eq = Sum(Piecewise((-p**k*(1 - p)**(-k + n)*log(p**k*(1 - p)**(-k + n)*binomial(n, k))*binomial(n, k), (k >= 0) & (k <= n)), (nan, True)), (k, 0, n))
assert eq.dummy_eq(H(B))
|
1490a1b81c8583f6711f524a4094b2dc679c610dfab3484f14e35ccea86ca64b | from sympy import (symbols, pi, oo, S, exp, sqrt, besselk, Indexed, Sum, simplify,
Rational, factorial, gamma, Piecewise, Eq, Product, Interval,
IndexedBase, RisingFactorial, polar_lift, ProductSet, Range, eye,
Determinant)
from sympy.core.numbers import comp
from sympy.integrals.integrals import integrate
from sympy.matrices import Matrix, MatrixSymbol
from sympy.matrices.expressions.matexpr import MatrixElement
from sympy.stats import density, median, marginal_distribution, Normal, Laplace, E, sample
from sympy.stats.joint_rv_types import (JointRV, MultivariateNormalDistribution,
JointDistributionHandmade, MultivariateT, NormalGamma,
GeneralizedMultivariateLogGammaOmega as GMVLGO, MultivariateBeta,
GeneralizedMultivariateLogGamma as GMVLG, MultivariateEwens,
Multinomial, NegativeMultinomial, MultivariateNormal,
MultivariateLaplace)
from sympy.testing.pytest import raises, XFAIL, skip
from sympy.external import import_module
x, y, z, a, b = symbols('x y z a b')
def test_Normal():
m = Normal('A', [1, 2], [[1, 0], [0, 1]])
A = MultivariateNormal('A', [1, 2], [[1, 0], [0, 1]])
assert m == A
assert density(m)(1, 2) == 1/(2*pi)
assert m.pspace.distribution.set == ProductSet(S.Reals, S.Reals)
raises (ValueError, lambda:m[2])
raises (ValueError,\
lambda: Normal('M',[1, 2], [[0, 0], [0, 1]]))
n = Normal('B', [1, 2, 3], [[1, 0, 0], [0, 1, 0], [0, 0, 1]])
p = Normal('C', Matrix([1, 2]), Matrix([[1, 0], [0, 1]]))
assert density(m)(x, y) == density(p)(x, y)
assert marginal_distribution(n, 0, 1)(1, 2) == 1/(2*pi)
raises(ValueError, lambda: marginal_distribution(m))
assert integrate(density(m)(x, y), (x, -oo, oo), (y, -oo, oo)).evalf() == 1
N = Normal('N', [1, 2], [[x, 0], [0, y]])
assert density(N)(0, 0) == exp(-((4*x + y)/(2*x*y)))/(2*pi*sqrt(x*y))
raises (ValueError, lambda: Normal('M', [1, 2], [[1, 1], [1, -1]]))
# symbolic
n = symbols('n', natural=True)
mu = MatrixSymbol('mu', n, 1)
sigma = MatrixSymbol('sigma', n, n)
X = Normal('X', mu, sigma)
assert density(X) == MultivariateNormalDistribution(mu, sigma)
raises (NotImplementedError, lambda: median(m))
# Below tests should work after issue #17267 is resolved
# assert E(X) == mu
# assert variance(X) == sigma
# test symbolic multivariate normal densities
n = 3
Sg = MatrixSymbol('Sg', n, n)
mu = MatrixSymbol('mu', n, 1)
obs = MatrixSymbol('obs', n, 1)
X = MultivariateNormal('X', mu, Sg)
density_X = density(X)
eval_a = density_X(obs).subs({Sg: eye(3),
mu: Matrix([0, 0, 0]), obs: Matrix([0, 0, 0])}).doit()
eval_b = density_X(0, 0, 0).subs({Sg: eye(3), mu: Matrix([0, 0, 0])}).doit()
assert eval_a == sqrt(2)/(4*pi**Rational(3/2))
assert eval_b == sqrt(2)/(4*pi**Rational(3/2))
n = symbols('n', natural=True)
Sg = MatrixSymbol('Sg', n, n)
mu = MatrixSymbol('mu', n, 1)
obs = MatrixSymbol('obs', n, 1)
X = MultivariateNormal('X', mu, Sg)
density_X_at_obs = density(X)(obs)
expected_density = MatrixElement(
exp((S(1)/2) * (mu.T - obs.T) * Sg**(-1) * (-mu + obs)) / \
sqrt((2*pi)**n * Determinant(Sg)), 0, 0)
assert density_X_at_obs == expected_density
def test_MultivariateTDist():
t1 = MultivariateT('T', [0, 0], [[1, 0], [0, 1]], 2)
assert(density(t1))(1, 1) == 1/(8*pi)
assert t1.pspace.distribution.set == ProductSet(S.Reals, S.Reals)
assert integrate(density(t1)(x, y), (x, -oo, oo), \
(y, -oo, oo)).evalf() == 1
raises(ValueError, lambda: MultivariateT('T', [1, 2], [[1, 1], [1, -1]], 1))
t2 = MultivariateT('t2', [1, 2], [[x, 0], [0, y]], 1)
assert density(t2)(1, 2) == 1/(2*pi*sqrt(x*y))
def test_multivariate_laplace():
raises(ValueError, lambda: Laplace('T', [1, 2], [[1, 2], [2, 1]]))
L = Laplace('L', [1, 0], [[1, 0], [0, 1]])
L2 = MultivariateLaplace('L2', [1, 0], [[1, 0], [0, 1]])
assert density(L)(2, 3) == exp(2)*besselk(0, sqrt(39))/pi
L1 = Laplace('L1', [1, 2], [[x, 0], [0, y]])
assert density(L1)(0, 1) == \
exp(2/y)*besselk(0, sqrt((2 + 4/y + 1/x)/y))/(pi*sqrt(x*y))
assert L.pspace.distribution.set == ProductSet(S.Reals, S.Reals)
assert L.pspace.distribution == L2.pspace.distribution
def test_NormalGamma():
ng = NormalGamma('G', 1, 2, 3, 4)
assert density(ng)(1, 1) == 32*exp(-4)/sqrt(pi)
assert ng.pspace.distribution.set == ProductSet(S.Reals, Interval(0, oo))
raises(ValueError, lambda:NormalGamma('G', 1, 2, 3, -1))
assert marginal_distribution(ng, 0)(1) == \
3*sqrt(10)*gamma(Rational(7, 4))/(10*sqrt(pi)*gamma(Rational(5, 4)))
assert marginal_distribution(ng, y)(1) == exp(Rational(-1, 4))/128
assert marginal_distribution(ng,[0,1])(x) == x**2*exp(-x/4)/128
def test_GeneralizedMultivariateLogGammaDistribution():
h = S.Half
omega = Matrix([[1, h, h, h],
[h, 1, h, h],
[h, h, 1, h],
[h, h, h, 1]])
v, l, mu = (4, [1, 2, 3, 4], [1, 2, 3, 4])
y_1, y_2, y_3, y_4 = symbols('y_1:5', real=True)
delta = symbols('d', positive=True)
G = GMVLGO('G', omega, v, l, mu)
Gd = GMVLG('Gd', delta, v, l, mu)
dend = ("d**4*Sum(4*24**(-n - 4)*(1 - d)**n*exp((n + 4)*(y_1 + 2*y_2 + 3*y_3 "
"+ 4*y_4) - exp(y_1) - exp(2*y_2)/2 - exp(3*y_3)/3 - exp(4*y_4)/4)/"
"(gamma(n + 1)*gamma(n + 4)**3), (n, 0, oo))")
assert str(density(Gd)(y_1, y_2, y_3, y_4)) == dend
den = ("5*2**(2/3)*5**(1/3)*Sum(4*24**(-n - 4)*(-2**(2/3)*5**(1/3)/4 + 1)**n*"
"exp((n + 4)*(y_1 + 2*y_2 + 3*y_3 + 4*y_4) - exp(y_1) - exp(2*y_2)/2 - "
"exp(3*y_3)/3 - exp(4*y_4)/4)/(gamma(n + 1)*gamma(n + 4)**3), (n, 0, oo))/64")
assert str(density(G)(y_1, y_2, y_3, y_4)) == den
marg = ("5*2**(2/3)*5**(1/3)*exp(4*y_1)*exp(-exp(y_1))*Integral(exp(-exp(4*G[3])"
"/4)*exp(16*G[3])*Integral(exp(-exp(3*G[2])/3)*exp(12*G[2])*Integral(exp("
"-exp(2*G[1])/2)*exp(8*G[1])*Sum((-1/4)**n*(-4 + 2**(2/3)*5**(1/3"
"))**n*exp(n*y_1)*exp(2*n*G[1])*exp(3*n*G[2])*exp(4*n*G[3])/(24**n*gamma(n + 1)"
"*gamma(n + 4)**3), (n, 0, oo)), (G[1], -oo, oo)), (G[2], -oo, oo)), (G[3]"
", -oo, oo))/5308416")
assert str(marginal_distribution(G, G[0])(y_1)) == marg
omega_f1 = Matrix([[1, h, h]])
omega_f2 = Matrix([[1, h, h, h],
[h, 1, 2, h],
[h, h, 1, h],
[h, h, h, 1]])
omega_f3 = Matrix([[6, h, h, h],
[h, 1, 2, h],
[h, h, 1, h],
[h, h, h, 1]])
v_f = symbols("v_f", positive=False, real=True)
l_f = [1, 2, v_f, 4]
m_f = [v_f, 2, 3, 4]
omega_f4 = Matrix([[1, h, h, h, h],
[h, 1, h, h, h],
[h, h, 1, h, h],
[h, h, h, 1, h],
[h, h, h, h, 1]])
l_f1 = [1, 2, 3, 4, 5]
omega_f5 = Matrix([[1]])
mu_f5 = l_f5 = [1]
raises(ValueError, lambda: GMVLGO('G', omega_f1, v, l, mu))
raises(ValueError, lambda: GMVLGO('G', omega_f2, v, l, mu))
raises(ValueError, lambda: GMVLGO('G', omega_f3, v, l, mu))
raises(ValueError, lambda: GMVLGO('G', omega, v_f, l, mu))
raises(ValueError, lambda: GMVLGO('G', omega, v, l_f, mu))
raises(ValueError, lambda: GMVLGO('G', omega, v, l, m_f))
raises(ValueError, lambda: GMVLGO('G', omega_f4, v, l, mu))
raises(ValueError, lambda: GMVLGO('G', omega, v, l_f1, mu))
raises(ValueError, lambda: GMVLGO('G', omega_f5, v, l_f5, mu_f5))
raises(ValueError, lambda: GMVLG('G', Rational(3, 2), v, l, mu))
def test_MultivariateBeta():
a1, a2 = symbols('a1, a2', positive=True)
a1_f, a2_f = symbols('a1, a2', positive=False, real=True)
mb = MultivariateBeta('B', [a1, a2])
mb_c = MultivariateBeta('C', a1, a2)
assert density(mb)(1, 2) == S(2)**(a2 - 1)*gamma(a1 + a2)/\
(gamma(a1)*gamma(a2))
assert marginal_distribution(mb_c, 0)(3) == S(3)**(a1 - 1)*gamma(a1 + a2)/\
(a2*gamma(a1)*gamma(a2))
raises(ValueError, lambda: MultivariateBeta('b1', [a1_f, a2]))
raises(ValueError, lambda: MultivariateBeta('b2', [a1, a2_f]))
raises(ValueError, lambda: MultivariateBeta('b3', [0, 0]))
raises(ValueError, lambda: MultivariateBeta('b4', [a1_f, a2_f]))
assert mb.pspace.distribution.set == ProductSet(Interval(0, 1), Interval(0, 1))
def test_MultivariateEwens():
n, theta, i = symbols('n theta i', positive=True)
# tests for integer dimensions
theta_f = symbols('t_f', negative=True)
a = symbols('a_1:4', positive = True, integer = True)
ed = MultivariateEwens('E', 3, theta)
assert density(ed)(a[0], a[1], a[2]) == Piecewise((6*2**(-a[1])*3**(-a[2])*
theta**a[0]*theta**a[1]*theta**a[2]/
(theta*(theta + 1)*(theta + 2)*
factorial(a[0])*factorial(a[1])*
factorial(a[2])), Eq(a[0] + 2*a[1] +
3*a[2], 3)), (0, True))
assert marginal_distribution(ed, ed[1])(a[1]) == Piecewise((6*2**(-a[1])*
theta**a[1]/((theta + 1)*
(theta + 2)*factorial(a[1])),
Eq(2*a[1] + 1, 3)), (0, True))
raises(ValueError, lambda: MultivariateEwens('e1', 5, theta_f))
assert ed.pspace.distribution.set == ProductSet(Range(0, 4, 1),
Range(0, 2, 1), Range(0, 2, 1))
# tests for symbolic dimensions
eds = MultivariateEwens('E', n, theta)
a = IndexedBase('a')
j, k = symbols('j, k')
den = Piecewise((factorial(n)*Product(theta**a[j]*(j + 1)**(-a[j])/
factorial(a[j]), (j, 0, n - 1))/RisingFactorial(theta, n),
Eq(n, Sum((k + 1)*a[k], (k, 0, n - 1)))), (0, True))
assert density(eds)(a).dummy_eq(den)
def test_Multinomial():
n, x1, x2, x3, x4 = symbols('n, x1, x2, x3, x4', nonnegative=True, integer=True)
p1, p2, p3, p4 = symbols('p1, p2, p3, p4', positive=True)
p1_f, n_f = symbols('p1_f, n_f', negative=True)
M = Multinomial('M', n, [p1, p2, p3, p4])
C = Multinomial('C', 3, p1, p2, p3)
f = factorial
assert density(M)(x1, x2, x3, x4) == Piecewise((p1**x1*p2**x2*p3**x3*p4**x4*
f(n)/(f(x1)*f(x2)*f(x3)*f(x4)),
Eq(n, x1 + x2 + x3 + x4)), (0, True))
assert marginal_distribution(C, C[0])(x1).subs(x1, 1) ==\
3*p1*p2**2 +\
6*p1*p2*p3 +\
3*p1*p3**2
raises(ValueError, lambda: Multinomial('b1', 5, [p1, p2, p3, p1_f]))
raises(ValueError, lambda: Multinomial('b2', n_f, [p1, p2, p3, p4]))
raises(ValueError, lambda: Multinomial('b3', n, 0.5, 0.4, 0.3, 0.1))
def test_NegativeMultinomial():
k0, x1, x2, x3, x4 = symbols('k0, x1, x2, x3, x4', nonnegative=True, integer=True)
p1, p2, p3, p4 = symbols('p1, p2, p3, p4', positive=True)
p1_f = symbols('p1_f', negative=True)
N = NegativeMultinomial('N', 4, [p1, p2, p3, p4])
C = NegativeMultinomial('C', 4, 0.1, 0.2, 0.3)
g = gamma
f = factorial
assert simplify(density(N)(x1, x2, x3, x4) -
p1**x1*p2**x2*p3**x3*p4**x4*(-p1 - p2 - p3 - p4 + 1)**4*g(x1 + x2 +
x3 + x4 + 4)/(6*f(x1)*f(x2)*f(x3)*f(x4))) is S.Zero
assert comp(marginal_distribution(C, C[0])(1).evalf(), 0.33, .01)
raises(ValueError, lambda: NegativeMultinomial('b1', 5, [p1, p2, p3, p1_f]))
raises(ValueError, lambda: NegativeMultinomial('b2', k0, 0.5, 0.4, 0.3, 0.4))
assert N.pspace.distribution.set == ProductSet(Range(0, oo, 1),
Range(0, oo, 1), Range(0, oo, 1), Range(0, oo, 1))
def test_JointPSpace_marginal_distribution():
T = MultivariateT('T', [0, 0], [[1, 0], [0, 1]], 2)
assert marginal_distribution(T, T[1])(x) == sqrt(2)*(x**2 + 2)/(
8*polar_lift(x**2/2 + 1)**Rational(5, 2))
assert integrate(marginal_distribution(T, 1)(x), (x, -oo, oo)) == 1
t = MultivariateT('T', [0, 0, 0], [[1, 0, 0], [0, 1, 0], [0, 0, 1]], 3)
assert comp(marginal_distribution(t, 0)(1).evalf(), 0.2, .01)
def test_JointRV():
x1, x2 = (Indexed('x', i) for i in (1, 2))
pdf = exp(-x1**2/2 + x1 - x2**2/2 - S.Half)/(2*pi)
X = JointRV('x', pdf)
assert density(X)(1, 2) == exp(-2)/(2*pi)
assert isinstance(X.pspace.distribution, JointDistributionHandmade)
assert marginal_distribution(X, 0)(2) == sqrt(2)*exp(Rational(-1, 2))/(2*sqrt(pi))
def test_expectation():
m = Normal('A', [x, y], [[1, 0], [0, 1]])
assert simplify(E(m[1])) == y
@XFAIL
def test_joint_vector_expectation():
m = Normal('A', [x, y], [[1, 0], [0, 1]])
assert E(m) == (x, y)
def test_sample_numpy():
distribs_numpy = [
MultivariateNormal("M", [3, 4], [[2, 1], [1, 2]]),
MultivariateBeta("B", [0.4, 5, 15, 50, 203]),
Multinomial("N", 50, [0.3, 0.2, 0.1, 0.25, 0.15])
]
size = 3
numpy = import_module('numpy')
if not numpy:
skip('Numpy is not installed. Abort tests for _sample_numpy.')
else:
for X in distribs_numpy:
samps = sample(X, size=size, library='numpy')
for sam in samps:
assert tuple(sam) in X.pspace.distribution.set
N_c = NegativeMultinomial('N', 3, 0.1, 0.1, 0.1)
raises(NotImplementedError, lambda: sample(N_c, library='numpy'))
def test_sample_scipy():
distribs_scipy = [
MultivariateNormal("M", [0, 0], [[0.1, 0.025], [0.025, 0.1]]),
MultivariateBeta("B", [0.4, 5, 15]),
Multinomial("N", 8, [0.3, 0.2, 0.1, 0.4])
]
size = 3
scipy = import_module('scipy')
if not scipy:
skip('Scipy not installed. Abort tests for _sample_scipy.')
else:
for X in distribs_scipy:
samps = sample(X, size=size)
samps2 = sample(X, size=(2, 2))
for sam in samps:
assert tuple(sam) in X.pspace.distribution.set
for i in range(2):
for j in range(2):
assert tuple(samps2[i][j]) in X.pspace.distribution.set
N_c = NegativeMultinomial('N', 3, 0.1, 0.1, 0.1)
raises(NotImplementedError, lambda: sample(N_c))
def test_sample_pymc3():
distribs_pymc3 = [
MultivariateNormal("M", [5, 2], [[1, 0], [0, 1]]),
MultivariateBeta("B", [0.4, 5, 15]),
Multinomial("N", 4, [0.3, 0.2, 0.1, 0.4])
]
size = 3
pymc3 = import_module('pymc3')
if not pymc3:
skip('PyMC3 is not installed. Abort tests for _sample_pymc3.')
else:
for X in distribs_pymc3:
samps = sample(X, size=size, library='pymc3')
for sam in samps:
assert tuple(sam.flatten()) in X.pspace.distribution.set
N_c = NegativeMultinomial('N', 3, 0.1, 0.1, 0.1)
raises(NotImplementedError, lambda: sample(N_c, library='pymc3'))
def test_sample_seed():
x1, x2 = (Indexed('x', i) for i in (1, 2))
pdf = exp(-x1**2/2 + x1 - x2**2/2 - S.Half)/(2*pi)
X = JointRV('x', pdf)
libraries = ['scipy', 'numpy', 'pymc3']
for lib in libraries:
try:
imported_lib = import_module(lib)
if imported_lib:
s0, s1, s2 = [], [], []
s0 = sample(X, size=10, library=lib, seed=0)
s1 = sample(X, size=10, library=lib, seed=0)
s2 = sample(X, size=10, library=lib, seed=1)
assert all(s0 == s1)
assert all(s1 != s2)
except NotImplementedError:
continue
|
d2fe1b200a00968706ff1dba64ad79fbe6e9aabf79f8faebdbaa3a6f523a03fc | from sympy import exp, S, sqrt, pi, symbols, Product, gamma, Dummy
from sympy.matrices import Determinant, Matrix, Trace, MatrixSymbol, MatrixSet
from sympy.stats import density, sample
from sympy.stats.matrix_distributions import (MatrixGammaDistribution,
MatrixGamma, MatrixPSpace, Wishart, MatrixNormal, MatrixStudentT)
from sympy.testing.pytest import raises, skip
from sympy.external import import_module
def test_MatrixPSpace():
M = MatrixGammaDistribution(1, 2, [[2, 1], [1, 2]])
MP = MatrixPSpace('M', M, 2, 2)
assert MP.distribution == M
raises(ValueError, lambda: MatrixPSpace('M', M, 1.2, 2))
def test_MatrixGamma():
M = MatrixGamma('M', 1, 2, [[1, 0], [0, 1]])
assert M.pspace.distribution.set == MatrixSet(2, 2, S.Reals)
assert isinstance(density(M), MatrixGammaDistribution)
X = MatrixSymbol('X', 2, 2)
num = exp(Trace(Matrix([[-S(1)/2, 0], [0, -S(1)/2]])*X))
assert density(M)(X).doit() == num/(4*pi*sqrt(Determinant(X)))
assert density(M)([[2, 1], [1, 2]]).doit() == sqrt(3)*exp(-2)/(12*pi)
X = MatrixSymbol('X', 1, 2)
Y = MatrixSymbol('Y', 1, 2)
assert density(M)([X, Y]).doit() == exp(-X[0, 0]/2 - Y[0, 1]/2)/(4*pi*sqrt(
X[0, 0]*Y[0, 1] - X[0, 1]*Y[0, 0]))
# symbolic
a, b = symbols('a b', positive=True)
d = symbols('d', positive=True, integer=True)
Y = MatrixSymbol('Y', d, d)
Z = MatrixSymbol('Z', 2, 2)
SM = MatrixSymbol('SM', d, d)
M2 = MatrixGamma('M2', a, b, SM)
M3 = MatrixGamma('M3', 2, 3, [[2, 1], [1, 2]])
k = Dummy('k')
exprd = pi**(-d*(d - 1)/4)*b**(-a*d)*exp(Trace((-1/b)*SM**(-1)*Y)
)*Determinant(SM)**(-a)*Determinant(Y)**(a - d/2 - S(1)/2)/Product(
gamma(-k/2 + a + S(1)/2), (k, 1, d))
assert density(M2)(Y).dummy_eq(exprd)
raises(NotImplementedError, lambda: density(M3 + M)(Z))
raises(ValueError, lambda: density(M)(1))
raises(ValueError, lambda: MatrixGamma('M', -1, 2, [[1, 0], [0, 1]]))
raises(ValueError, lambda: MatrixGamma('M', -1, -2, [[1, 0], [0, 1]]))
raises(ValueError, lambda: MatrixGamma('M', -1, 2, [[1, 0], [2, 1]]))
raises(ValueError, lambda: MatrixGamma('M', -1, 2, [[1, 0], [0]]))
def test_Wishart():
W = Wishart('W', 5, [[1, 0], [0, 1]])
assert W.pspace.distribution.set == MatrixSet(2, 2, S.Reals)
X = MatrixSymbol('X', 2, 2)
term1 = exp(Trace(Matrix([[-S(1)/2, 0], [0, -S(1)/2]])*X))
assert density(W)(X).doit() == term1 * Determinant(X)/(24*pi)
assert density(W)([[2, 1], [1, 2]]).doit() == exp(-2)/(8*pi)
n = symbols('n', positive=True)
d = symbols('d', positive=True, integer=True)
Y = MatrixSymbol('Y', d, d)
SM = MatrixSymbol('SM', d, d)
W = Wishart('W', n, SM)
k = Dummy('k')
exprd = 2**(-d*n/2)*pi**(-d*(d - 1)/4)*exp(Trace(-(S(1)/2)*SM**(-1)*Y)
)*Determinant(SM)**(-n/2)*Determinant(Y)**(
-d/2 + n/2 - S(1)/2)/Product(gamma(-k/2 + n/2 + S(1)/2), (k, 1, d))
assert density(W)(Y).dummy_eq(exprd)
raises(ValueError, lambda: density(W)(1))
raises(ValueError, lambda: Wishart('W', -1, [[1, 0], [0, 1]]))
raises(ValueError, lambda: Wishart('W', -1, [[1, 0], [2, 1]]))
raises(ValueError, lambda: Wishart('W', 2, [[1, 0], [0]]))
def test_MatrixNormal():
M = MatrixNormal('M', [[5, 6]], [4], [[2, 1], [1, 2]])
assert M.pspace.distribution.set == MatrixSet(1, 2, S.Reals)
X = MatrixSymbol('X', 1, 2)
term1 = exp(-Trace(Matrix([[ S(2)/3, -S(1)/3], [-S(1)/3, S(2)/3]])*(
Matrix([[-5], [-6]]) + X.T)*Matrix([[1/4]])*(Matrix([[-5, -6]]) + X))/2)
assert density(M)(X).doit() == term1/(24*pi)
assert density(M)([[7, 8]]).doit() == exp(-S(1)/3)/(24*pi)
d, n = symbols('d n', positive=True, integer=True)
SM2 = MatrixSymbol('SM2', d, d)
SM1 = MatrixSymbol('SM1', n, n)
LM = MatrixSymbol('LM', n, d)
Y = MatrixSymbol('Y', n, d)
M = MatrixNormal('M', LM, SM1, SM2)
exprd = 4*(2*pi)**(-d*n/2)*exp(-Trace(SM2**(-1)*(-LM.T + Y.T)*SM1**(-1)*(-LM + Y)
)/2)*Determinant(SM1)**(-d)*Determinant(SM2)**(-n)
assert density(M)(Y).doit() == exprd
raises(ValueError, lambda: density(M)(1))
raises(ValueError, lambda: MatrixNormal('M', [1, 2], [[1, 0], [0, 1]], [[1, 0], [2, 1]]))
raises(ValueError, lambda: MatrixNormal('M', [1, 2], [[1, 0], [2, 1]], [[1, 0], [0, 1]]))
raises(ValueError, lambda: MatrixNormal('M', [1, 2], [[1, 0], [0, 1]], [[1, 0], [0, 1]]))
raises(ValueError, lambda: MatrixNormal('M', [1, 2], [[1, 0], [2]], [[1, 0], [0, 1]]))
raises(ValueError, lambda: MatrixNormal('M', [1, 2], [[1, 0], [2, 1]], [[1, 0], [0]]))
raises(ValueError, lambda: MatrixNormal('M', [[1, 2]], [[1, 0], [0, 1]], [[1, 0]]))
raises(ValueError, lambda: MatrixNormal('M', [[1, 2]], [1], [[1, 0]]))
def test_MatrixStudentT():
M = MatrixStudentT('M', 2, [[5, 6]], [[2, 1], [1, 2]], [4])
assert M.pspace.distribution.set == MatrixSet(1, 2, S.Reals)
X = MatrixSymbol('X', 1, 2)
D = pi ** (-1.0) * Determinant(Matrix([[4]])) ** (-1.0) * Determinant(Matrix([[2, 1], [1, 2]])) \
** (-0.5) / Determinant(Matrix([[S(1) / 4]]) * (Matrix([[-5, -6]]) + X)
* Matrix([[S(2) / 3, -S(1) / 3], [-S(1) / 3, S(2) / 3]]) * (
Matrix([[-5], [-6]]) + X.T) + Matrix([[1]])) ** 2
assert density(M)(X) == D
v = symbols('v', positive=True)
n, p = 1, 2
Omega = MatrixSymbol('Omega', p, p)
Sigma = MatrixSymbol('Sigma', n, n)
Location = MatrixSymbol('Location', n, p)
Y = MatrixSymbol('Y', n, p)
M = MatrixStudentT('M', v, Location, Omega, Sigma)
exprd = gamma(v/2 + 1)*Determinant(Matrix([[1]]) + Sigma**(-1)*(-Location + Y)*Omega**(-1)*(-Location.T + Y.T))**(-v/2 - 1) / \
(pi*gamma(v/2)*sqrt(Determinant(Omega))*Determinant(Sigma))
assert density(M)(Y) == exprd
raises(ValueError, lambda: density(M)(1))
raises(ValueError, lambda: MatrixStudentT('M', 1, [1, 2], [[1, 0], [0, 1]], [[1, 0], [2, 1]]))
raises(ValueError, lambda: MatrixStudentT('M', 1, [1, 2], [[1, 0], [2, 1]], [[1, 0], [0, 1]]))
raises(ValueError, lambda: MatrixStudentT('M', 1, [1, 2], [[1, 0], [0, 1]], [[1, 0], [0, 1]]))
raises(ValueError, lambda: MatrixStudentT('M', 1, [1, 2], [[1, 0], [2]], [[1, 0], [0, 1]]))
raises(ValueError, lambda: MatrixStudentT('M', 1, [1, 2], [[1, 0], [2, 1]], [[1], [2]]))
raises(ValueError, lambda: MatrixStudentT('M', 1, [[1, 2]], [[1, 0], [0, 1]], [[1, 0]]))
raises(ValueError, lambda: MatrixStudentT('M', 1, [[1, 2]], [1], [[1, 0]]))
raises(ValueError, lambda: MatrixStudentT('M', -1, [1, 2], [[1, 0], [0, 1]], [4]))
def test_sample_scipy():
distribs_scipy = [
MatrixNormal('M', [[5, 6]], [4], [[2, 1], [1, 2]]),
Wishart('W', 5, [[1, 0], [0, 1]])
]
size = 5
scipy = import_module('scipy')
if not scipy:
skip('Scipy not installed. Abort tests for _sample_scipy.')
else:
for X in distribs_scipy:
samps = sample(X, size=size)
for sam in samps:
assert Matrix(sam) in X.pspace.distribution.set
M = MatrixGamma('M', 1, 2, [[1, 0], [0, 1]])
raises(NotImplementedError, lambda: sample(M, size=3))
def test_sample_pymc3():
distribs_pymc3 = [
MatrixNormal('M', [[5, 6], [3, 4]], [[1, 0], [0, 1]], [[2, 1], [1, 2]]),
Wishart('W', 7, [[2, 1], [1, 2]])
]
size = 3
pymc3 = import_module('pymc3')
if not pymc3:
skip('PyMC3 is not installed. Abort tests for _sample_pymc3.')
else:
for X in distribs_pymc3:
samps = sample(X, size=size, library='pymc3')
for sam in samps:
assert Matrix(sam) in X.pspace.distribution.set
M = MatrixGamma('M', 1, 2, [[1, 0], [0, 1]])
raises(NotImplementedError, lambda: sample(M, size=3))
def test_sample_seed():
X = MatrixNormal('M', [[5, 6], [3, 4]], [[1, 0], [0, 1]], [[2, 1], [1, 2]])
libraries = ['scipy', 'numpy', 'pymc3']
for lib in libraries:
try:
imported_lib = import_module(lib)
if imported_lib:
s0, s1, s2 = [], [], []
s0 = sample(X, size=10, library=lib, seed=0)
s1 = sample(X, size=10, library=lib, seed=0)
s2 = sample(X, size=10, library=lib, seed=1)
for i in range(10):
assert (s0[i] == s1[i]).all()
assert (s1[i] != s2[i]).all()
except NotImplementedError:
continue
|
b71d33dea47d8ef3d85b17643f8595fd780cbaf515ca196b0ebea872748a3db1 | from sympy import S, Rational
from sympy.external import import_module
from sympy.stats import Binomial, sample, Die, FiniteRV, DiscreteUniform, Bernoulli, BetaBinomial, Hypergeometric, \
Rademacher
from sympy.testing.pytest import skip, raises
def test_given_sample():
X = Die('X', 6)
scipy = import_module('scipy')
if not scipy:
skip('Scipy is not installed. Abort tests')
assert sample(X, X > 5) == 6
def test_sample_numpy():
distribs_numpy = [
Binomial("B", 5, 0.4),
]
size = 3
numpy = import_module('numpy')
if not numpy:
skip('Numpy is not installed. Abort tests for _sample_numpy.')
else:
for X in distribs_numpy:
samps = sample(X, size=size, library='numpy')
for sam in samps:
assert sam in X.pspace.domain.set
raises(NotImplementedError,
lambda: sample(Die("D"), library='numpy'))
raises(NotImplementedError,
lambda: Die("D").pspace.sample(library='tensorflow'))
def test_sample_scipy():
distribs_scipy = [
FiniteRV('F', {1: S.Half, 2: Rational(1, 4), 3: Rational(1, 4)}),
DiscreteUniform("Y", list(range(5))),
Die("D"),
Bernoulli("Be", 0.3),
Binomial("Bi", 5, 0.4),
BetaBinomial("Bb", 2, 1, 1),
Hypergeometric("H", 1, 1, 1),
Rademacher("R")
]
size = 3
scipy = import_module('scipy')
if not scipy:
skip('Scipy not installed. Abort tests for _sample_scipy.')
else:
for X in distribs_scipy:
samps = sample(X, size=size)
samps2 = sample(X, size=(2, 2))
for sam in samps:
assert sam in X.pspace.domain.set
for i in range(2):
for j in range(2):
assert samps2[i][j] in X.pspace.domain.set
def test_sample_pymc3():
distribs_pymc3 = [
Bernoulli('B', 0.2),
Binomial('N', 5, 0.4)
]
size = 3
pymc3 = import_module('pymc3')
if not pymc3:
skip('PyMC3 is not installed. Abort tests for _sample_pymc3.')
else:
for X in distribs_pymc3:
samps = sample(X, size=size, library='pymc3')
for sam in samps:
assert sam in X.pspace.domain.set
raises(NotImplementedError,
lambda: (sample(Die("D"), library='pymc3')))
def test_sample_seed():
F = FiniteRV('F', {1: S.Half, 2: Rational(1, 4), 3: Rational(1, 4)})
size = 10
libraries = ['scipy', 'numpy', 'pymc3']
for lib in libraries:
try:
imported_lib = import_module(lib)
if imported_lib:
s0 = sample(F, size=size, library=lib, seed=0)
s1 = sample(F, size=size, library=lib, seed=0)
s2 = sample(F, size=size, library=lib, seed=1)
assert all(s0 == s1)
assert not all(s1 == s2)
except NotImplementedError:
continue
|
517b8196f16457474a74405013a69bf1ca668c49a19df34b23d1a8e33b3bba88 | from sympy import exp, Interval, oo, Symbol
from sympy.external import import_module
from sympy.stats import Beta, Chi, Normal, Gamma, Exponential, LogNormal, Pareto, ChiSquared, Uniform, sample, \
BetaPrime, Cauchy, GammaInverse, GaussianInverse, StudentT, Weibull, density, ContinuousRV
from sympy.testing.pytest import skip, raises
def test_sample_numpy():
distribs_numpy = [
Beta("B", 1, 1),
Normal("N", 0, 1),
Gamma("G", 2, 7),
Exponential("E", 2),
LogNormal("LN", 0, 1),
Pareto("P", 1, 1),
ChiSquared("CS", 2),
Uniform("U", 0, 1)
]
size = 3
numpy = import_module('numpy')
if not numpy:
skip('Numpy is not installed. Abort tests for _sample_numpy.')
else:
for X in distribs_numpy:
samps = sample(X, size=size, library='numpy')
for sam in samps:
assert sam in X.pspace.domain.set
raises(NotImplementedError,
lambda: sample(Chi("C", 1), library='numpy'))
raises(NotImplementedError,
lambda: Chi("C", 1).pspace.distribution.sample(library='tensorflow'))
def test_sample_scipy():
distribs_scipy = [
Beta("B", 1, 1),
BetaPrime("BP", 1, 1),
Cauchy("C", 1, 1),
Chi("C", 1),
Normal("N", 0, 1),
Gamma("G", 2, 7),
GammaInverse("GI", 1, 1),
GaussianInverse("GUI", 1, 1),
Exponential("E", 2),
LogNormal("LN", 0, 1),
Pareto("P", 1, 1),
StudentT("S", 2),
ChiSquared("CS", 2),
Uniform("U", 0, 1)
]
size = 3
scipy = import_module('scipy')
if not scipy:
skip('Scipy is not installed. Abort tests for _sample_scipy.')
else:
for X in distribs_scipy:
samps = sample(X, size=size, library='scipy')
samps2 = sample(X, size=(2, 2), library='scipy')
for sam in samps:
assert sam in X.pspace.domain.set
for i in range(2):
for j in range(2):
assert samps2[i][j] in X.pspace.domain.set
def test_sample_pymc3():
distribs_pymc3 = [
Beta("B", 1, 1),
Cauchy("C", 1, 1),
Normal("N", 0, 1),
Gamma("G", 2, 7),
GaussianInverse("GI", 1, 1),
Exponential("E", 2),
LogNormal("LN", 0, 1),
Pareto("P", 1, 1),
ChiSquared("CS", 2),
Uniform("U", 0, 1)
]
size = 3
pymc3 = import_module('pymc3')
if not pymc3:
skip('PyMC3 is not installed. Abort tests for _sample_pymc3.')
else:
for X in distribs_pymc3:
samps = sample(X, size=size, library='pymc3')
for sam in samps:
assert sam in X.pspace.domain.set
raises(NotImplementedError,
lambda: sample(Chi("C", 1), library='pymc3'))
def test_sampling_gamma_inverse():
scipy = import_module('scipy')
if not scipy:
skip('Scipy not installed. Abort tests for sampling of gamma inverse.')
X = GammaInverse("x", 1, 1)
assert sample(X) in X.pspace.domain.set
def test_lognormal_sampling():
# Right now, only density function and sampling works
scipy = import_module('scipy')
if not scipy:
skip('Scipy is not installed. Abort tests')
for i in range(3):
X = LogNormal('x', i, 1)
assert sample(X) in X.pspace.domain.set
size = 5
samps = sample(X, size=size)
for samp in samps:
assert samp in X.pspace.domain.set
def test_sampling_gaussian_inverse():
scipy = import_module('scipy')
if not scipy:
skip('Scipy not installed. Abort tests for sampling of Gaussian inverse.')
X = GaussianInverse("x", 1, 1)
assert sample(X, library='scipy') in X.pspace.domain.set
def test_prefab_sampling():
scipy = import_module('scipy')
if not scipy:
skip('Scipy is not installed. Abort tests')
N = Normal('X', 0, 1)
L = LogNormal('L', 0, 1)
E = Exponential('Ex', 1)
P = Pareto('P', 1, 3)
W = Weibull('W', 1, 1)
U = Uniform('U', 0, 1)
B = Beta('B', 2, 5)
G = Gamma('G', 1, 3)
variables = [N, L, E, P, W, U, B, G]
niter = 10
size = 5
for var in variables:
for _ in range(niter):
assert sample(var) in var.pspace.domain.set
samps = sample(var, size=size)
for samp in samps:
assert samp in var.pspace.domain.set
def test_sample_continuous():
z = Symbol('z')
Z = ContinuousRV(z, exp(-z), set=Interval(0, oo))
assert density(Z)(-1) == 0
scipy = import_module('scipy')
if not scipy:
skip('Scipy is not installed. Abort tests')
assert sample(Z) in Z.pspace.domain.set
sym, val = list(Z.pspace.sample().items())[0]
assert sym == Z and val in Interval(0, oo)
libraries = ['scipy', 'numpy', 'pymc3']
for lib in libraries:
try:
imported_lib = import_module(lib)
if imported_lib:
s0, s1, s2 = [], [], []
s0 = sample(Z, size=10, library=lib, seed=0)
s1 = sample(Z, size=10, library=lib, seed=0)
s2 = sample(Z, size=10, library=lib, seed=1)
assert all(s0 == s1)
assert all(s1 != s2)
except NotImplementedError:
continue
|
a482f6f887d3cfcca1c3c10c713cdde109edc1c9984125863ce164b3c5d13f13 | from sympy import S, Symbol
from sympy.external import import_module
from sympy.stats import Geometric, Poisson, Zeta, sample, Skellam, DiscreteRV, Logarithmic, NegativeBinomial, YuleSimon
from sympy.testing.pytest import skip, raises, slow
def test_sample_numpy():
distribs_numpy = [
Geometric('G', 0.5),
Poisson('P', 1),
Zeta('Z', 2)
]
size = 3
numpy = import_module('numpy')
if not numpy:
skip('Numpy is not installed. Abort tests for _sample_numpy.')
else:
for X in distribs_numpy:
samps = sample(X, size=size, library='numpy')
for sam in samps:
assert sam in X.pspace.domain.set
raises(NotImplementedError,
lambda: sample(Skellam('S', 1, 1), library='numpy'))
raises(NotImplementedError,
lambda: Skellam('S', 1, 1).pspace.distribution.sample(library='tensorflow'))
def test_sample_scipy():
p = S(2)/3
x = Symbol('x', integer=True, positive=True)
pdf = p*(1 - p)**(x - 1) # pdf of Geometric Distribution
distribs_scipy = [
DiscreteRV(x, pdf, set=S.Naturals),
Geometric('G', 0.5),
Logarithmic('L', 0.5),
NegativeBinomial('N', 5, 0.4),
Poisson('P', 1),
Skellam('S', 1, 1),
YuleSimon('Y', 1),
Zeta('Z', 2)
]
size = 3
scipy = import_module('scipy')
if not scipy:
skip('Scipy is not installed. Abort tests for _sample_scipy.')
else:
for X in distribs_scipy:
samps = sample(X, size=size, library='scipy')
samps2 = sample(X, size=(2, 2), library='scipy')
for sam in samps:
assert sam in X.pspace.domain.set
for i in range(2):
for j in range(2):
assert samps2[i][j] in X.pspace.domain.set
def test_sample_pymc3():
distribs_pymc3 = [
Geometric('G', 0.5),
Poisson('P', 1),
NegativeBinomial('N', 5, 0.4)
]
size = 3
pymc3 = import_module('pymc3')
if not pymc3:
skip('PyMC3 is not installed. Abort tests for _sample_pymc3.')
else:
for X in distribs_pymc3:
samps = sample(X, size=size, library='pymc3')
for sam in samps:
assert sam in X.pspace.domain.set
raises(NotImplementedError,
lambda: sample(Skellam('S', 1, 1), library='pymc3'))
@slow
def test_sample_discrete():
X = Geometric('X', S.Half)
scipy = import_module('scipy')
if not scipy:
skip('Scipy not installed. Abort tests')
assert sample(X) in X.pspace.domain.set
samps = sample(X, size=2) # This takes long time if ran without scipy
for samp in samps:
assert samp in X.pspace.domain.set
libraries = ['scipy', 'numpy', 'pymc3']
for lib in libraries:
try:
imported_lib = import_module(lib)
if imported_lib:
s0, s1, s2 = [], [], []
s0 = sample(X, size=10, library=lib, seed=0)
s1 = sample(X, size=10, library=lib, seed=0)
s2 = sample(X, size=10, library=lib, seed=1)
assert all(s0 == s1)
assert not all(s1 == s2)
except NotImplementedError:
continue
|
e20f640fd5873a5f3c585da0ca77898dd5a95672e38627fa59d6b2db2ae5108e | from sympy.core.numbers import Rational
from sympy.ntheory.egyptian_fraction import egyptian_fraction
from sympy.core.add import Add
from sympy.testing.pytest import raises
from sympy.testing.randtest import random_complex_number
def test_egyptian_fraction():
def test_equality(r, alg="Greedy"):
return r == Add(*[Rational(1, i) for i in egyptian_fraction(r, alg)])
r = random_complex_number(a=0, c=1, b=0, d=0, rational=True)
assert test_equality(r)
assert egyptian_fraction(Rational(4, 17)) == [5, 29, 1233, 3039345]
assert egyptian_fraction(Rational(7, 13), "Greedy") == [2, 26]
assert egyptian_fraction(Rational(23, 101), "Greedy") == \
[5, 37, 1438, 2985448, 40108045937720]
assert egyptian_fraction(Rational(18, 23), "Takenouchi") == \
[2, 6, 12, 35, 276, 2415]
assert egyptian_fraction(Rational(5, 6), "Graham Jewett") == \
[6, 7, 8, 9, 10, 42, 43, 44, 45, 56, 57, 58, 72, 73, 90, 1806, 1807,
1808, 1892, 1893, 1980, 3192, 3193, 3306, 5256, 3263442, 3263443,
3267056, 3581556, 10192056, 10650056950806]
assert egyptian_fraction(Rational(5, 6), "Golomb") == [2, 6, 12, 20, 30]
assert egyptian_fraction(Rational(5, 121), "Golomb") == [25, 1225, 3577, 7081, 11737]
raises(ValueError, lambda: egyptian_fraction(Rational(-4, 9)))
assert egyptian_fraction(Rational(8, 3), "Golomb") == [1, 2, 3, 4, 5, 6, 7,
14, 574, 2788, 6460,
11590, 33062, 113820]
assert egyptian_fraction(Rational(355, 113)) == [1, 2, 3, 4, 5, 6, 7, 8, 9,
10, 11, 12, 27, 744, 893588,
1251493536607,
20361068938197002344405230]
def test_input():
r = (2,3), Rational(2, 3), (Rational(2), Rational(3))
for m in ["Greedy", "Graham Jewett", "Takenouchi", "Golomb"]:
for i in r:
d = egyptian_fraction(i, m)
assert all(i.is_Integer for i in d)
if m == "Graham Jewett":
assert d == [3, 4, 12]
else:
assert d == [2, 6]
# check prefix
d = egyptian_fraction(Rational(5, 3))
assert d == [1, 2, 6] and all(i.is_Integer for i in d)
|
ed7237817fce14065c2b2c05682dc5eab7400e2b14658ee94653fbfcec55b10d | from sympy import (
Abs, And, binomial, Catalan, combsimp, cos, Derivative, E, Eq, exp, EulerGamma,
factorial, Function, harmonic, I, Integral, KroneckerDelta, log,
nan, oo, pi, Piecewise, Product, product, Rational, S, simplify, Identity,
sin, sqrt, Sum, summation, Symbol, symbols, sympify, zeta, gamma,
Indexed, Idx, IndexedBase, prod, Dummy, lowergamma, Range, floor,
rf, MatrixSymbol, tanh, sinh)
from sympy.abc import a, b, c, d, k, m, x, y, z
from sympy.concrete.summations import (
telescopic, _dummy_with_inherited_properties_concrete, eval_sum_residue)
from sympy.concrete.expr_with_intlimits import ReorderError
from sympy.core.facts import InconsistentAssumptions
from sympy.testing.pytest import XFAIL, raises, slow
from sympy.matrices import \
Matrix, SparseMatrix, ImmutableDenseMatrix, ImmutableSparseMatrix
from sympy.core.mod import Mod
n = Symbol('n', integer=True)
def test_karr_convention():
# Test the Karr summation convention that we want to hold.
# See his paper "Summation in Finite Terms" for a detailed
# reasoning why we really want exactly this definition.
# The convention is described on page 309 and essentially
# in section 1.4, definition 3:
#
# \sum_{m <= i < n} f(i) 'has the obvious meaning' for m < n
# \sum_{m <= i < n} f(i) = 0 for m = n
# \sum_{m <= i < n} f(i) = - \sum_{n <= i < m} f(i) for m > n
#
# It is important to note that he defines all sums with
# the upper limit being *exclusive*.
# In contrast, sympy and the usual mathematical notation has:
#
# sum_{i = a}^b f(i) = f(a) + f(a+1) + ... + f(b-1) + f(b)
#
# with the upper limit *inclusive*. So translating between
# the two we find that:
#
# \sum_{m <= i < n} f(i) = \sum_{i = m}^{n-1} f(i)
#
# where we intentionally used two different ways to typeset the
# sum and its limits.
i = Symbol("i", integer=True)
k = Symbol("k", integer=True)
j = Symbol("j", integer=True)
# A simple example with a concrete summand and symbolic limits.
# The normal sum: m = k and n = k + j and therefore m < n:
m = k
n = k + j
a = m
b = n - 1
S1 = Sum(i**2, (i, a, b)).doit()
# The reversed sum: m = k + j and n = k and therefore m > n:
m = k + j
n = k
a = m
b = n - 1
S2 = Sum(i**2, (i, a, b)).doit()
assert simplify(S1 + S2) == 0
# Test the empty sum: m = k and n = k and therefore m = n:
m = k
n = k
a = m
b = n - 1
Sz = Sum(i**2, (i, a, b)).doit()
assert Sz == 0
# Another example this time with an unspecified summand and
# numeric limits. (We can not do both tests in the same example.)
f = Function("f")
# The normal sum with m < n:
m = 2
n = 11
a = m
b = n - 1
S1 = Sum(f(i), (i, a, b)).doit()
# The reversed sum with m > n:
m = 11
n = 2
a = m
b = n - 1
S2 = Sum(f(i), (i, a, b)).doit()
assert simplify(S1 + S2) == 0
# Test the empty sum with m = n:
m = 5
n = 5
a = m
b = n - 1
Sz = Sum(f(i), (i, a, b)).doit()
assert Sz == 0
e = Piecewise((exp(-i), Mod(i, 2) > 0), (0, True))
s = Sum(e, (i, 0, 11))
assert s.n(3) == s.doit().n(3)
def test_karr_proposition_2a():
# Test Karr, page 309, proposition 2, part a
i = Symbol("i", integer=True)
u = Symbol("u", integer=True)
v = Symbol("v", integer=True)
def test_the_sum(m, n):
# g
g = i**3 + 2*i**2 - 3*i
# f = Delta g
f = simplify(g.subs(i, i+1) - g)
# The sum
a = m
b = n - 1
S = Sum(f, (i, a, b)).doit()
# Test if Sum_{m <= i < n} f(i) = g(n) - g(m)
assert simplify(S - (g.subs(i, n) - g.subs(i, m))) == 0
# m < n
test_the_sum(u, u+v)
# m = n
test_the_sum(u, u )
# m > n
test_the_sum(u+v, u )
def test_karr_proposition_2b():
# Test Karr, page 309, proposition 2, part b
i = Symbol("i", integer=True)
u = Symbol("u", integer=True)
v = Symbol("v", integer=True)
w = Symbol("w", integer=True)
def test_the_sum(l, n, m):
# Summand
s = i**3
# First sum
a = l
b = n - 1
S1 = Sum(s, (i, a, b)).doit()
# Second sum
a = l
b = m - 1
S2 = Sum(s, (i, a, b)).doit()
# Third sum
a = m
b = n - 1
S3 = Sum(s, (i, a, b)).doit()
# Test if S1 = S2 + S3 as required
assert S1 - (S2 + S3) == 0
# l < m < n
test_the_sum(u, u+v, u+v+w)
# l < m = n
test_the_sum(u, u+v, u+v )
# l < m > n
test_the_sum(u, u+v+w, v )
# l = m < n
test_the_sum(u, u, u+v )
# l = m = n
test_the_sum(u, u, u )
# l = m > n
test_the_sum(u+v, u+v, u )
# l > m < n
test_the_sum(u+v, u, u+w )
# l > m = n
test_the_sum(u+v, u, u )
# l > m > n
test_the_sum(u+v+w, u+v, u )
def test_arithmetic_sums():
assert summation(1, (n, a, b)) == b - a + 1
assert Sum(S.NaN, (n, a, b)) is S.NaN
assert Sum(x, (n, a, a)).doit() == x
assert Sum(x, (x, a, a)).doit() == a
assert Sum(x, (n, 1, a)).doit() == a*x
assert Sum(x, (x, Range(1, 11))).doit() == 55
assert Sum(x, (x, Range(1, 11, 2))).doit() == 25
assert Sum(x, (x, Range(1, 10, 2))) == Sum(x, (x, Range(9, 0, -2)))
lo, hi = 1, 2
s1 = Sum(n, (n, lo, hi))
s2 = Sum(n, (n, hi, lo))
assert s1 != s2
assert s1.doit() == 3 and s2.doit() == 0
lo, hi = x, x + 1
s1 = Sum(n, (n, lo, hi))
s2 = Sum(n, (n, hi, lo))
assert s1 != s2
assert s1.doit() == 2*x + 1 and s2.doit() == 0
assert Sum(Integral(x, (x, 1, y)) + x, (x, 1, 2)).doit() == \
y**2 + 2
assert summation(1, (n, 1, 10)) == 10
assert summation(2*n, (n, 0, 10**10)) == 100000000010000000000
assert summation(4*n*m, (n, a, 1), (m, 1, d)).expand() == \
2*d + 2*d**2 + a*d + a*d**2 - d*a**2 - a**2*d**2
assert summation(cos(n), (n, -2, 1)) == cos(-2) + cos(-1) + cos(0) + cos(1)
assert summation(cos(n), (n, x, x + 2)) == cos(x) + cos(x + 1) + cos(x + 2)
assert isinstance(summation(cos(n), (n, x, x + S.Half)), Sum)
assert summation(k, (k, 0, oo)) is oo
assert summation(k, (k, Range(1, 11))) == 55
def test_polynomial_sums():
assert summation(n**2, (n, 3, 8)) == 199
assert summation(n, (n, a, b)) == \
((a + b)*(b - a + 1)/2).expand()
assert summation(n**2, (n, 1, b)) == \
((2*b**3 + 3*b**2 + b)/6).expand()
assert summation(n**3, (n, 1, b)) == \
((b**4 + 2*b**3 + b**2)/4).expand()
assert summation(n**6, (n, 1, b)) == \
((6*b**7 + 21*b**6 + 21*b**5 - 7*b**3 + b)/42).expand()
def test_geometric_sums():
assert summation(pi**n, (n, 0, b)) == (1 - pi**(b + 1)) / (1 - pi)
assert summation(2 * 3**n, (n, 0, b)) == 3**(b + 1) - 1
assert summation(S.Half**n, (n, 1, oo)) == 1
assert summation(2**n, (n, 0, b)) == 2**(b + 1) - 1
assert summation(2**n, (n, 1, oo)) is oo
assert summation(2**(-n), (n, 1, oo)) == 1
assert summation(3**(-n), (n, 4, oo)) == Rational(1, 54)
assert summation(2**(-4*n + 3), (n, 1, oo)) == Rational(8, 15)
assert summation(2**(n + 1), (n, 1, b)).expand() == 4*(2**b - 1)
# issue 6664:
assert summation(x**n, (n, 0, oo)) == \
Piecewise((1/(-x + 1), Abs(x) < 1), (Sum(x**n, (n, 0, oo)), True))
assert summation(-2**n, (n, 0, oo)) is -oo
assert summation(I**n, (n, 0, oo)) == Sum(I**n, (n, 0, oo))
# issue 6802:
assert summation((-1)**(2*x + 2), (x, 0, n)) == n + 1
assert summation((-2)**(2*x + 2), (x, 0, n)) == 4*4**(n + 1)/S(3) - Rational(4, 3)
assert summation((-1)**x, (x, 0, n)) == -(-1)**(n + 1)/S(2) + S.Half
assert summation(y**x, (x, a, b)) == \
Piecewise((-a + b + 1, Eq(y, 1)), ((y**a - y**(b + 1))/(-y + 1), True))
assert summation((-2)**(y*x + 2), (x, 0, n)) == \
4*Piecewise((n + 1, Eq((-2)**y, 1)),
((-(-2)**(y*(n + 1)) + 1)/(-(-2)**y + 1), True))
# issue 8251:
assert summation((1/(n + 1)**2)*n**2, (n, 0, oo)) is oo
#issue 9908:
assert Sum(1/(n**3 - 1), (n, -oo, -2)).doit() == summation(1/(n**3 - 1), (n, -oo, -2))
#issue 11642:
result = Sum(0.5**n, (n, 1, oo)).doit()
assert result == 1
assert result.is_Float
result = Sum(0.25**n, (n, 1, oo)).doit()
assert result == 1/3.
assert result.is_Float
result = Sum(0.99999**n, (n, 1, oo)).doit()
assert result == 99999
assert result.is_Float
result = Sum(S.Half**n, (n, 1, oo)).doit()
assert result == 1
assert not result.is_Float
result = Sum(Rational(3, 5)**n, (n, 1, oo)).doit()
assert result == Rational(3, 2)
assert not result.is_Float
assert Sum(1.0**n, (n, 1, oo)).doit() is oo
assert Sum(2.43**n, (n, 1, oo)).doit() is oo
# Issue 13979
i, k, q = symbols('i k q', integer=True)
result = summation(
exp(-2*I*pi*k*i/n) * exp(2*I*pi*q*i/n) / n, (i, 0, n - 1)
)
assert result.simplify() == Piecewise(
(1, Eq(exp(-2*I*pi*(k - q)/n), 1)), (0, True)
)
def test_harmonic_sums():
assert summation(1/k, (k, 0, n)) == Sum(1/k, (k, 0, n))
assert summation(1/k, (k, 1, n)) == harmonic(n)
assert summation(n/k, (k, 1, n)) == n*harmonic(n)
assert summation(1/k, (k, 5, n)) == harmonic(n) - harmonic(4)
def test_composite_sums():
f = S.Half*(7 - 6*n + Rational(1, 7)*n**3)
s = summation(f, (n, a, b))
assert not isinstance(s, Sum)
A = 0
for i in range(-3, 5):
A += f.subs(n, i)
B = s.subs(a, -3).subs(b, 4)
assert A == B
def test_hypergeometric_sums():
assert summation(
binomial(2*k, k)/4**k, (k, 0, n)) == (1 + 2*n)*binomial(2*n, n)/4**n
assert summation(binomial(2*k, k)/5**k, (k, -oo, oo)) == sqrt(5)
def test_other_sums():
f = m**2 + m*exp(m)
g = 3*exp(Rational(3, 2))/2 + exp(S.Half)/2 - exp(Rational(-1, 2))/2 - 3*exp(Rational(-3, 2))/2 + 5
assert summation(f, (m, Rational(-3, 2), Rational(3, 2))) == g
assert summation(f, (m, -1.5, 1.5)).evalf().epsilon_eq(g.evalf(), 1e-10)
fac = factorial
def NS(e, n=15, **options):
return str(sympify(e).evalf(n, **options))
def test_evalf_fast_series():
# Euler transformed series for sqrt(1+x)
assert NS(Sum(
fac(2*n + 1)/fac(n)**2/2**(3*n + 1), (n, 0, oo)), 100) == NS(sqrt(2), 100)
# Some series for exp(1)
estr = NS(E, 100)
assert NS(Sum(1/fac(n), (n, 0, oo)), 100) == estr
assert NS(1/Sum((1 - 2*n)/fac(2*n), (n, 0, oo)), 100) == estr
assert NS(Sum((2*n + 1)/fac(2*n), (n, 0, oo)), 100) == estr
assert NS(Sum((4*n + 3)/2**(2*n + 1)/fac(2*n + 1), (n, 0, oo))**2, 100) == estr
pistr = NS(pi, 100)
# Ramanujan series for pi
assert NS(9801/sqrt(8)/Sum(fac(
4*n)*(1103 + 26390*n)/fac(n)**4/396**(4*n), (n, 0, oo)), 100) == pistr
assert NS(1/Sum(
binomial(2*n, n)**3 * (42*n + 5)/2**(12*n + 4), (n, 0, oo)), 100) == pistr
# Machin's formula for pi
assert NS(16*Sum((-1)**n/(2*n + 1)/5**(2*n + 1), (n, 0, oo)) -
4*Sum((-1)**n/(2*n + 1)/239**(2*n + 1), (n, 0, oo)), 100) == pistr
# Apery's constant
astr = NS(zeta(3), 100)
P = 126392*n**5 + 412708*n**4 + 531578*n**3 + 336367*n**2 + 104000* \
n + 12463
assert NS(Sum((-1)**n * P / 24 * (fac(2*n + 1)*fac(2*n)*fac(
n))**3 / fac(3*n + 2) / fac(4*n + 3)**3, (n, 0, oo)), 100) == astr
assert NS(Sum((-1)**n * (205*n**2 + 250*n + 77)/64 * fac(n)**10 /
fac(2*n + 1)**5, (n, 0, oo)), 100) == astr
def test_evalf_fast_series_issue_4021():
# Catalan's constant
assert NS(Sum((-1)**(n - 1)*2**(8*n)*(40*n**2 - 24*n + 3)*fac(2*n)**3*
fac(n)**2/n**3/(2*n - 1)/fac(4*n)**2, (n, 1, oo))/64, 100) == \
NS(Catalan, 100)
astr = NS(zeta(3), 100)
assert NS(5*Sum(
(-1)**(n - 1)*fac(n)**2 / n**3 / fac(2*n), (n, 1, oo))/2, 100) == astr
assert NS(Sum((-1)**(n - 1)*(56*n**2 - 32*n + 5) / (2*n - 1)**2 * fac(n - 1)
**3 / fac(3*n), (n, 1, oo))/4, 100) == astr
def test_evalf_slow_series():
assert NS(Sum((-1)**n / n, (n, 1, oo)), 15) == NS(-log(2), 15)
assert NS(Sum((-1)**n / n, (n, 1, oo)), 50) == NS(-log(2), 50)
assert NS(Sum(1/n**2, (n, 1, oo)), 15) == NS(pi**2/6, 15)
assert NS(Sum(1/n**2, (n, 1, oo)), 100) == NS(pi**2/6, 100)
assert NS(Sum(1/n**2, (n, 1, oo)), 500) == NS(pi**2/6, 500)
assert NS(Sum((-1)**n / (2*n + 1)**3, (n, 0, oo)), 15) == NS(pi**3/32, 15)
assert NS(Sum((-1)**n / (2*n + 1)**3, (n, 0, oo)), 50) == NS(pi**3/32, 50)
def test_euler_maclaurin():
# Exact polynomial sums with E-M
def check_exact(f, a, b, m, n):
A = Sum(f, (k, a, b))
s, e = A.euler_maclaurin(m, n)
assert (e == 0) and (s.expand() == A.doit())
check_exact(k**4, a, b, 0, 2)
check_exact(k**4 + 2*k, a, b, 1, 2)
check_exact(k**4 + k**2, a, b, 1, 5)
check_exact(k**5, 2, 6, 1, 2)
check_exact(k**5, 2, 6, 1, 3)
assert Sum(x-1, (x, 0, 2)).euler_maclaurin(m=30, n=30, eps=2**-15) == (0, 0)
# Not exact
assert Sum(k**6, (k, a, b)).euler_maclaurin(0, 2)[1] != 0
# Numerical test
for mi, ni in [(2, 4), (2, 20), (10, 20), (18, 20)]:
A = Sum(1/k**3, (k, 1, oo))
s, e = A.euler_maclaurin(mi, ni)
assert abs((s - zeta(3)).evalf()) < e.evalf()
raises(ValueError, lambda: Sum(1, (x, 0, 1), (k, 0, 1)).euler_maclaurin())
@slow
def test_evalf_euler_maclaurin():
assert NS(Sum(1/k**k, (k, 1, oo)), 15) == '1.29128599706266'
assert NS(Sum(1/k**k, (k, 1, oo)),
50) == '1.2912859970626635404072825905956005414986193682745'
assert NS(Sum(1/k - log(1 + 1/k), (k, 1, oo)), 15) == NS(EulerGamma, 15)
assert NS(Sum(1/k - log(1 + 1/k), (k, 1, oo)), 50) == NS(EulerGamma, 50)
assert NS(Sum(log(k)/k**2, (k, 1, oo)), 15) == '0.937548254315844'
assert NS(Sum(log(k)/k**2, (k, 1, oo)),
50) == '0.93754825431584375370257409456786497789786028861483'
assert NS(Sum(1/k, (k, 1000000, 2000000)), 15) == '0.693147930560008'
assert NS(Sum(1/k, (k, 1000000, 2000000)),
50) == '0.69314793056000780941723211364567656807940638436025'
def test_evalf_symbolic():
f, g = symbols('f g', cls=Function)
# issue 6328
expr = Sum(f(x), (x, 1, 3)) + Sum(g(x), (x, 1, 3))
assert expr.evalf() == expr
def test_evalf_issue_3273():
assert Sum(0, (k, 1, oo)).evalf() == 0
def test_simple_products():
assert Product(S.NaN, (x, 1, 3)) is S.NaN
assert product(S.NaN, (x, 1, 3)) is S.NaN
assert Product(x, (n, a, a)).doit() == x
assert Product(x, (x, a, a)).doit() == a
assert Product(x, (y, 1, a)).doit() == x**a
lo, hi = 1, 2
s1 = Product(n, (n, lo, hi))
s2 = Product(n, (n, hi, lo))
assert s1 != s2
# This IS correct according to Karr product convention
assert s1.doit() == 2
assert s2.doit() == 1
lo, hi = x, x + 1
s1 = Product(n, (n, lo, hi))
s2 = Product(n, (n, hi, lo))
s3 = 1 / Product(n, (n, hi + 1, lo - 1))
assert s1 != s2
# This IS correct according to Karr product convention
assert s1.doit() == x*(x + 1)
assert s2.doit() == 1
assert s3.doit() == x*(x + 1)
assert Product(Integral(2*x, (x, 1, y)) + 2*x, (x, 1, 2)).doit() == \
(y**2 + 1)*(y**2 + 3)
assert product(2, (n, a, b)) == 2**(b - a + 1)
assert product(n, (n, 1, b)) == factorial(b)
assert product(n**3, (n, 1, b)) == factorial(b)**3
assert product(3**(2 + n), (n, a, b)) \
== 3**(2*(1 - a + b) + b/2 + (b**2)/2 + a/2 - (a**2)/2)
assert product(cos(n), (n, 3, 5)) == cos(3)*cos(4)*cos(5)
assert product(cos(n), (n, x, x + 2)) == cos(x)*cos(x + 1)*cos(x + 2)
assert isinstance(product(cos(n), (n, x, x + S.Half)), Product)
# If Product managed to evaluate this one, it most likely got it wrong!
assert isinstance(Product(n**n, (n, 1, b)), Product)
def test_rational_products():
assert combsimp(product(1 + 1/n, (n, a, b))) == (1 + b)/a
assert combsimp(product(n + 1, (n, a, b))) == gamma(2 + b)/gamma(1 + a)
assert combsimp(product((n + 1)/(n - 1), (n, a, b))) == b*(1 + b)/(a*(a - 1))
assert combsimp(product(n/(n + 1)/(n + 2), (n, a, b))) == \
a*gamma(a + 2)/(b + 1)/gamma(b + 3)
assert combsimp(product(n*(n + 1)/(n - 1)/(n - 2), (n, a, b))) == \
b**2*(b - 1)*(1 + b)/(a - 1)**2/(a*(a - 2))
def test_wallis_product():
# Wallis product, given in two different forms to ensure that Product
# can factor simple rational expressions
A = Product(4*n**2 / (4*n**2 - 1), (n, 1, b))
B = Product((2*n)*(2*n)/(2*n - 1)/(2*n + 1), (n, 1, b))
R = pi*gamma(b + 1)**2/(2*gamma(b + S.Half)*gamma(b + Rational(3, 2)))
assert simplify(A.doit()) == R
assert simplify(B.doit()) == R
# This one should eventually also be doable (Euler's product formula for sin)
# assert Product(1+x/n**2, (n, 1, b)) == ...
def test_telescopic_sums():
#checks also input 2 of comment 1 issue 4127
assert Sum(1/k - 1/(k + 1), (k, 1, n)).doit() == 1 - 1/(1 + n)
f = Function("f")
assert Sum(
f(k) - f(k + 2), (k, m, n)).doit() == -f(1 + n) - f(2 + n) + f(m) + f(1 + m)
assert Sum(cos(k) - cos(k + 3), (k, 1, n)).doit() == -cos(1 + n) - \
cos(2 + n) - cos(3 + n) + cos(1) + cos(2) + cos(3)
# dummy variable shouldn't matter
assert telescopic(1/m, -m/(1 + m), (m, n - 1, n)) == \
telescopic(1/k, -k/(1 + k), (k, n - 1, n))
assert Sum(1/x/(x - 1), (x, a, b)).doit() == -((a - b - 1)/(b*(a - 1)))
def test_sum_reconstruct():
s = Sum(n**2, (n, -1, 1))
assert s == Sum(*s.args)
raises(ValueError, lambda: Sum(x, x))
raises(ValueError, lambda: Sum(x, (x, 1)))
def test_limit_subs():
for F in (Sum, Product, Integral):
assert F(a*exp(a), (a, -2, 2)) == F(a*exp(a), (a, -b, b)).subs(b, 2)
assert F(a, (a, F(b, (b, 1, 2)), 4)).subs(F(b, (b, 1, 2)), c) == \
F(a, (a, c, 4))
assert F(x, (x, 1, x + y)).subs(x, 1) == F(x, (x, 1, y + 1))
def test_function_subs():
f = Function("f")
S = Sum(x*f(y),(x,0,oo),(y,0,oo))
assert S.subs(f(y),y) == Sum(x*y,(x,0,oo),(y,0,oo))
assert S.subs(f(x),x) == S
raises(ValueError, lambda: S.subs(f(y),x+y) )
S = Sum(x*log(y),(x,0,oo),(y,0,oo))
assert S.subs(log(y),y) == S
S = Sum(x*f(y),(x,0,oo),(y,0,oo))
assert S.subs(f(y),y) == Sum(x*y,(x,0,oo),(y,0,oo))
def test_equality():
# if this fails remove special handling below
raises(ValueError, lambda: Sum(x, x))
r = symbols('x', real=True)
for F in (Sum, Product, Integral):
try:
assert F(x, x) != F(y, y)
assert F(x, (x, 1, 2)) != F(x, x)
assert F(x, (x, x)) != F(x, x) # or else they print the same
assert F(1, x) != F(1, y)
except ValueError:
pass
assert F(a, (x, 1, 2)) != F(a, (x, 1, 3)) # diff limit
assert F(a, (x, 1, x)) != F(a, (y, 1, y))
assert F(a, (x, 1, 2)) != F(b, (x, 1, 2)) # diff expression
assert F(x, (x, 1, 2)) != F(r, (r, 1, 2)) # diff assumptions
assert F(1, (x, 1, x)) != F(1, (y, 1, x)) # only dummy is diff
assert F(1, (x, 1, x)).dummy_eq(F(1, (y, 1, x)))
# issue 5265
assert Sum(x, (x, 1, x)).subs(x, a) == Sum(x, (x, 1, a))
def test_Sum_doit():
f = Function('f')
assert Sum(n*Integral(a**2), (n, 0, 2)).doit() == a**3
assert Sum(n*Integral(a**2), (n, 0, 2)).doit(deep=False) == \
3*Integral(a**2)
assert summation(n*Integral(a**2), (n, 0, 2)) == 3*Integral(a**2)
# test nested sum evaluation
s = Sum( Sum( Sum(2,(z,1,n+1)), (y,x+1,n)), (x,1,n))
assert 0 == (s.doit() - n*(n+1)*(n-1)).factor()
# Integer assumes finite
assert Sum(KroneckerDelta(x, y), (x, -oo, oo)).doit() == Piecewise((1, And(-oo <= y, y < oo)), (0, True))
assert Sum(KroneckerDelta(m, n), (m, -oo, oo)).doit() == 1
assert Sum(m*KroneckerDelta(x, y), (x, -oo, oo)).doit() == Piecewise((m, And(-oo <= y, y < oo)), (0, True))
assert Sum(x*KroneckerDelta(m, n), (m, -oo, oo)).doit() == x
assert Sum(Sum(KroneckerDelta(m, n), (m, 1, 3)), (n, 1, 3)).doit() == 3
assert Sum(Sum(KroneckerDelta(k, m), (m, 1, 3)), (n, 1, 3)).doit() == \
3 * Piecewise((1, And(1 <= k, k <= 3)), (0, True))
assert Sum(f(n) * Sum(KroneckerDelta(m, n), (m, 0, oo)), (n, 1, 3)).doit() == \
f(1) + f(2) + f(3)
assert Sum(f(n) * Sum(KroneckerDelta(m, n), (m, 0, oo)), (n, 1, oo)).doit() == \
Sum(f(n), (n, 1, oo))
# issue 2597
nmax = symbols('N', integer=True, positive=True)
pw = Piecewise((1, And(1 <= n, n <= nmax)), (0, True))
assert Sum(pw, (n, 1, nmax)).doit() == Sum(Piecewise((1, nmax >= n),
(0, True)), (n, 1, nmax))
q, s = symbols('q, s')
assert summation(1/n**(2*s), (n, 1, oo)) == Piecewise((zeta(2*s), 2*s > 1),
(Sum(n**(-2*s), (n, 1, oo)), True))
assert summation(1/(n+1)**s, (n, 0, oo)) == Piecewise((zeta(s), s > 1),
(Sum((n + 1)**(-s), (n, 0, oo)), True))
assert summation(1/(n+q)**s, (n, 0, oo)) == Piecewise(
(zeta(s, q), And(q > 0, s > 1)),
(Sum((n + q)**(-s), (n, 0, oo)), True))
assert summation(1/(n+q)**s, (n, q, oo)) == Piecewise(
(zeta(s, 2*q), And(2*q > 0, s > 1)),
(Sum((n + q)**(-s), (n, q, oo)), True))
assert summation(1/n**2, (n, 1, oo)) == zeta(2)
assert summation(1/n**s, (n, 0, oo)) == Sum(n**(-s), (n, 0, oo))
def test_Product_doit():
assert Product(n*Integral(a**2), (n, 1, 3)).doit() == 2 * a**9 / 9
assert Product(n*Integral(a**2), (n, 1, 3)).doit(deep=False) == \
6*Integral(a**2)**3
assert product(n*Integral(a**2), (n, 1, 3)) == 6*Integral(a**2)**3
def test_Sum_interface():
assert isinstance(Sum(0, (n, 0, 2)), Sum)
assert Sum(nan, (n, 0, 2)) is nan
assert Sum(nan, (n, 0, oo)) is nan
assert Sum(0, (n, 0, 2)).doit() == 0
assert isinstance(Sum(0, (n, 0, oo)), Sum)
assert Sum(0, (n, 0, oo)).doit() == 0
raises(ValueError, lambda: Sum(1))
raises(ValueError, lambda: summation(1))
def test_diff():
assert Sum(x, (x, 1, 2)).diff(x) == 0
assert Sum(x*y, (x, 1, 2)).diff(x) == 0
assert Sum(x*y, (y, 1, 2)).diff(x) == Sum(y, (y, 1, 2))
e = Sum(x*y, (x, 1, a))
assert e.diff(a) == Derivative(e, a)
assert Sum(x*y, (x, 1, 3), (a, 2, 5)).diff(y).doit() == \
Sum(x*y, (x, 1, 3), (a, 2, 5)).doit().diff(y) == 24
assert Sum(x, (x, 1, 2)).diff(y) == 0
def test_hypersum():
from sympy import sin
assert simplify(summation(x**n/fac(n), (n, 1, oo))) == -1 + exp(x)
assert summation((-1)**n * x**(2*n) / fac(2*n), (n, 0, oo)) == cos(x)
assert simplify(summation((-1)**n*x**(2*n + 1) /
factorial(2*n + 1), (n, 3, oo))) == -x + sin(x) + x**3/6 - x**5/120
assert summation(1/(n + 2)**3, (n, 1, oo)) == Rational(-9, 8) + zeta(3)
assert summation(1/n**4, (n, 1, oo)) == pi**4/90
s = summation(x**n*n, (n, -oo, 0))
assert s.is_Piecewise
assert s.args[0].args[0] == -1/(x*(1 - 1/x)**2)
assert s.args[0].args[1] == (abs(1/x) < 1)
m = Symbol('n', integer=True, positive=True)
assert summation(binomial(m, k), (k, 0, m)) == 2**m
def test_issue_4170():
assert summation(1/factorial(k), (k, 0, oo)) == E
def test_is_commutative():
from sympy.physics.secondquant import NO, F, Fd
m = Symbol('m', commutative=False)
for f in (Sum, Product, Integral):
assert f(z, (z, 1, 1)).is_commutative is True
assert f(z*y, (z, 1, 6)).is_commutative is True
assert f(m*x, (x, 1, 2)).is_commutative is False
assert f(NO(Fd(x)*F(y))*z, (z, 1, 2)).is_commutative is False
def test_is_zero():
for func in [Sum, Product]:
assert func(0, (x, 1, 1)).is_zero is True
assert func(x, (x, 1, 1)).is_zero is None
assert Sum(0, (x, 1, 0)).is_zero is True
assert Product(0, (x, 1, 0)).is_zero is False
def test_is_number():
# is number should not rely on evaluation or assumptions,
# it should be equivalent to `not foo.free_symbols`
assert Sum(1, (x, 1, 1)).is_number is True
assert Sum(1, (x, 1, x)).is_number is False
assert Sum(0, (x, y, z)).is_number is False
assert Sum(x, (y, 1, 2)).is_number is False
assert Sum(x, (y, 1, 1)).is_number is False
assert Sum(x, (x, 1, 2)).is_number is True
assert Sum(x*y, (x, 1, 2), (y, 1, 3)).is_number is True
assert Product(2, (x, 1, 1)).is_number is True
assert Product(2, (x, 1, y)).is_number is False
assert Product(0, (x, y, z)).is_number is False
assert Product(1, (x, y, z)).is_number is False
assert Product(x, (y, 1, x)).is_number is False
assert Product(x, (y, 1, 2)).is_number is False
assert Product(x, (y, 1, 1)).is_number is False
assert Product(x, (x, 1, 2)).is_number is True
def test_free_symbols():
for func in [Sum, Product]:
assert func(1, (x, 1, 2)).free_symbols == set()
assert func(0, (x, 1, y)).free_symbols == {y}
assert func(2, (x, 1, y)).free_symbols == {y}
assert func(x, (x, 1, 2)).free_symbols == set()
assert func(x, (x, 1, y)).free_symbols == {y}
assert func(x, (y, 1, y)).free_symbols == {x, y}
assert func(x, (y, 1, 2)).free_symbols == {x}
assert func(x, (y, 1, 1)).free_symbols == {x}
assert func(x, (y, 1, z)).free_symbols == {x, z}
assert func(x, (x, 1, y), (y, 1, 2)).free_symbols == set()
assert func(x, (x, 1, y), (y, 1, z)).free_symbols == {z}
assert func(x, (x, 1, y), (y, 1, y)).free_symbols == {y}
assert func(x, (y, 1, y), (y, 1, z)).free_symbols == {x, z}
assert Sum(1, (x, 1, y)).free_symbols == {y}
# free_symbols answers whether the object *as written* has free symbols,
# not whether the evaluated expression has free symbols
assert Product(1, (x, 1, y)).free_symbols == {y}
def test_conjugate_transpose():
A, B = symbols("A B", commutative=False)
p = Sum(A*B**n, (n, 1, 3))
assert p.adjoint().doit() == p.doit().adjoint()
assert p.conjugate().doit() == p.doit().conjugate()
assert p.transpose().doit() == p.doit().transpose()
p = Sum(B**n*A, (n, 1, 3))
assert p.adjoint().doit() == p.doit().adjoint()
assert p.conjugate().doit() == p.doit().conjugate()
assert p.transpose().doit() == p.doit().transpose()
def test_noncommutativity_honoured():
A, B = symbols("A B", commutative=False)
M = symbols('M', integer=True, positive=True)
p = Sum(A*B**n, (n, 1, M))
assert p.doit() == A*Piecewise((M, Eq(B, 1)),
((B - B**(M + 1))*(1 - B)**(-1), True))
p = Sum(B**n*A, (n, 1, M))
assert p.doit() == Piecewise((M, Eq(B, 1)),
((B - B**(M + 1))*(1 - B)**(-1), True))*A
p = Sum(B**n*A*B**n, (n, 1, M))
assert p.doit() == p
def test_issue_4171():
assert summation(factorial(2*k + 1)/factorial(2*k), (k, 0, oo)) is oo
assert summation(2*k + 1, (k, 0, oo)) is oo
def test_issue_6273():
assert Sum(x, (x, 1, n)).n(2, subs={n: 1}) == 1
def test_issue_6274():
assert Sum(x, (x, 1, 0)).doit() == 0
assert NS(Sum(x, (x, 1, 0))) == '0'
assert Sum(n, (n, 10, 5)).doit() == -30
assert NS(Sum(n, (n, 10, 5))) == '-30.0000000000000'
def test_simplify_sum():
y, t, v = symbols('y, t, v')
_simplify = lambda e: simplify(e, doit=False)
assert _simplify(Sum(x*y, (x, n, m), (y, a, k)) + \
Sum(y, (x, n, m), (y, a, k))) == Sum(y * (x + 1), (x, n, m), (y, a, k))
assert _simplify(Sum(x, (x, n, m)) + Sum(x, (x, m + 1, a))) == \
Sum(x, (x, n, a))
assert _simplify(Sum(x, (x, k + 1, a)) + Sum(x, (x, n, k))) == \
Sum(x, (x, n, a))
assert _simplify(Sum(x, (x, k + 1, a)) + Sum(x + 1, (x, n, k))) == \
Sum(x, (x, n, a)) + Sum(1, (x, n, k))
assert _simplify(Sum(x, (x, 0, 3)) * 3 + 3 * Sum(x, (x, 4, 6)) + \
4 * Sum(z, (z, 0, 1))) == 4*Sum(z, (z, 0, 1)) + 3*Sum(x, (x, 0, 6))
assert _simplify(3*Sum(x**2, (x, a, b)) + Sum(x, (x, a, b))) == \
Sum(x*(3*x + 1), (x, a, b))
assert _simplify(Sum(x**3, (x, n, k)) * 3 + 3 * Sum(x, (x, n, k)) + \
4 * y * Sum(z, (z, n, k))) + 1 == \
4*y*Sum(z, (z, n, k)) + 3*Sum(x**3 + x, (x, n, k)) + 1
assert _simplify(Sum(x, (x, a, b)) + 1 + Sum(x, (x, b + 1, c))) == \
1 + Sum(x, (x, a, c))
assert _simplify(Sum(x, (t, a, b)) + Sum(y, (t, a, b)) + \
Sum(x, (t, b+1, c))) == x * Sum(1, (t, a, c)) + y * Sum(1, (t, a, b))
assert _simplify(Sum(x, (t, a, b)) + Sum(x, (t, b+1, c)) + \
Sum(y, (t, a, b))) == x * Sum(1, (t, a, c)) + y * Sum(1, (t, a, b))
assert _simplify(Sum(x, (t, a, b)) + 2 * Sum(x, (t, b+1, c))) == \
_simplify(Sum(x, (t, a, b)) + Sum(x, (t, b+1, c)) + Sum(x, (t, b+1, c)))
assert _simplify(Sum(x, (x, a, b))*Sum(x**2, (x, a, b))) == \
Sum(x, (x, a, b)) * Sum(x**2, (x, a, b))
assert _simplify(Sum(x, (t, a, b)) + Sum(y, (t, a, b)) + Sum(z, (t, a, b))) \
== (x + y + z) * Sum(1, (t, a, b)) # issue 8596
assert _simplify(Sum(x, (t, a, b)) + Sum(y, (t, a, b)) + Sum(z, (t, a, b)) + \
Sum(v, (t, a, b))) == (x + y + z + v) * Sum(1, (t, a, b)) # issue 8596
assert _simplify(Sum(x * y, (x, a, b)) / (3 * y)) == \
(Sum(x, (x, a, b)) / 3)
assert _simplify(Sum(Function('f')(x) * y * z, (x, a, b)) / (y * z)) \
== Sum(Function('f')(x), (x, a, b))
assert _simplify(Sum(c * x, (x, a, b)) - c * Sum(x, (x, a, b))) == 0
assert _simplify(c * (Sum(x, (x, a, b)) + y)) == c * (y + Sum(x, (x, a, b)))
assert _simplify(c * (Sum(x, (x, a, b)) + y * Sum(x, (x, a, b)))) == \
c * (y + 1) * Sum(x, (x, a, b))
assert _simplify(Sum(Sum(c * x, (x, a, b)), (y, a, b))) == \
c * Sum(x, (x, a, b), (y, a, b))
assert _simplify(Sum((3 + y) * Sum(c * x, (x, a, b)), (y, a, b))) == \
c * Sum((3 + y), (y, a, b)) * Sum(x, (x, a, b))
assert _simplify(Sum((3 + t) * Sum(c * t, (x, a, b)), (y, a, b))) == \
c*t*(t + 3)*Sum(1, (x, a, b))*Sum(1, (y, a, b))
assert _simplify(Sum(Sum(d * t, (x, a, b - 1)) + \
Sum(d * t, (x, b, c)), (t, a, b))) == \
d * Sum(1, (x, a, c)) * Sum(t, (t, a, b))
def test_change_index():
b, v, w = symbols('b, v, w', integer = True)
assert Sum(x, (x, a, b)).change_index(x, x + 1, y) == \
Sum(y - 1, (y, a + 1, b + 1))
assert Sum(x**2, (x, a, b)).change_index( x, x - 1) == \
Sum((x+1)**2, (x, a - 1, b - 1))
assert Sum(x**2, (x, a, b)).change_index( x, -x, y) == \
Sum((-y)**2, (y, -b, -a))
assert Sum(x, (x, a, b)).change_index( x, -x - 1) == \
Sum(-x - 1, (x, -b - 1, -a - 1))
assert Sum(x*y, (x, a, b), (y, c, d)).change_index( x, x - 1, z) == \
Sum((z + 1)*y, (z, a - 1, b - 1), (y, c, d))
assert Sum(x, (x, a, b)).change_index( x, x + v) == \
Sum(-v + x, (x, a + v, b + v))
assert Sum(x, (x, a, b)).change_index( x, -x - v) == \
Sum(-v - x, (x, -b - v, -a - v))
assert Sum(x, (x, a, b)).change_index(x, w*x, v) == \
Sum(v/w, (v, b*w, a*w))
raises(ValueError, lambda: Sum(x, (x, a, b)).change_index(x, 2*x))
def test_reorder():
b, y, c, d, z = symbols('b, y, c, d, z', integer = True)
assert Sum(x*y, (x, a, b), (y, c, d)).reorder((0, 1)) == \
Sum(x*y, (y, c, d), (x, a, b))
assert Sum(x, (x, a, b), (x, c, d)).reorder((0, 1)) == \
Sum(x, (x, c, d), (x, a, b))
assert Sum(x*y + z, (x, a, b), (z, m, n), (y, c, d)).reorder(\
(2, 0), (0, 1)) == Sum(x*y + z, (z, m, n), (y, c, d), (x, a, b))
assert Sum(x*y*z, (x, a, b), (y, c, d), (z, m, n)).reorder(\
(0, 1), (1, 2), (0, 2)) == Sum(x*y*z, (x, a, b), (z, m, n), (y, c, d))
assert Sum(x*y*z, (x, a, b), (y, c, d), (z, m, n)).reorder(\
(x, y), (y, z), (x, z)) == Sum(x*y*z, (x, a, b), (z, m, n), (y, c, d))
assert Sum(x*y, (x, a, b), (y, c, d)).reorder((x, 1)) == \
Sum(x*y, (y, c, d), (x, a, b))
assert Sum(x*y, (x, a, b), (y, c, d)).reorder((y, x)) == \
Sum(x*y, (y, c, d), (x, a, b))
def test_reverse_order():
assert Sum(x, (x, 0, 3)).reverse_order(0) == Sum(-x, (x, 4, -1))
assert Sum(x*y, (x, 1, 5), (y, 0, 6)).reverse_order(0, 1) == \
Sum(x*y, (x, 6, 0), (y, 7, -1))
assert Sum(x, (x, 1, 2)).reverse_order(0) == Sum(-x, (x, 3, 0))
assert Sum(x, (x, 1, 3)).reverse_order(0) == Sum(-x, (x, 4, 0))
assert Sum(x, (x, 1, a)).reverse_order(0) == Sum(-x, (x, a + 1, 0))
assert Sum(x, (x, a, 5)).reverse_order(0) == Sum(-x, (x, 6, a - 1))
assert Sum(x, (x, a + 1, a + 5)).reverse_order(0) == \
Sum(-x, (x, a + 6, a))
assert Sum(x, (x, a + 1, a + 2)).reverse_order(0) == \
Sum(-x, (x, a + 3, a))
assert Sum(x, (x, a + 1, a + 1)).reverse_order(0) == \
Sum(-x, (x, a + 2, a))
assert Sum(x, (x, a, b)).reverse_order(0) == Sum(-x, (x, b + 1, a - 1))
assert Sum(x, (x, a, b)).reverse_order(x) == Sum(-x, (x, b + 1, a - 1))
assert Sum(x*y, (x, a, b), (y, 2, 5)).reverse_order(x, 1) == \
Sum(x*y, (x, b + 1, a - 1), (y, 6, 1))
assert Sum(x*y, (x, a, b), (y, 2, 5)).reverse_order(y, x) == \
Sum(x*y, (x, b + 1, a - 1), (y, 6, 1))
def test_issue_7097():
assert sum(x**n/n for n in range(1, 401)) == summation(x**n/n, (n, 1, 400))
def test_factor_expand_subs():
# test factoring
assert Sum(4 * x, (x, 1, y)).factor() == 4 * Sum(x, (x, 1, y))
assert Sum(x * a, (x, 1, y)).factor() == a * Sum(x, (x, 1, y))
assert Sum(4 * x * a, (x, 1, y)).factor() == 4 * a * Sum(x, (x, 1, y))
assert Sum(4 * x * y, (x, 1, y)).factor() == 4 * y * Sum(x, (x, 1, y))
# test expand
assert Sum(x+1,(x,1,y)).expand() == Sum(x,(x,1,y)) + Sum(1,(x,1,y))
assert Sum(x+a*x**2,(x,1,y)).expand() == Sum(x,(x,1,y)) + Sum(a*x**2,(x,1,y))
assert Sum(x**(n + 1)*(n + 1), (n, -1, oo)).expand() \
== Sum(x*x**n, (n, -1, oo)) + Sum(n*x*x**n, (n, -1, oo))
assert Sum(x**(n + 1)*(n + 1), (n, -1, oo)).expand(power_exp=False) \
== Sum(n*x**(n+1), (n, -1, oo)) + Sum(x**(n+1), (n, -1, oo))
assert Sum(a*n+a*n**2,(n,0,4)).expand() \
== Sum(a*n,(n,0,4)) + Sum(a*n**2,(n,0,4))
assert Sum(x**a*x**n,(x,0,3)) \
== Sum(x**(a+n),(x,0,3)).expand(power_exp=True)
assert Sum(x**(a+n),(x,0,3)) \
== Sum(x**(a+n),(x,0,3)).expand(power_exp=False)
# test subs
assert Sum(1/(1+a*x**2),(x,0,3)).subs([(a,3)]) == Sum(1/(1+3*x**2),(x,0,3))
assert Sum(x*y,(x,0,y),(y,0,x)).subs([(x,3)]) == Sum(x*y,(x,0,y),(y,0,3))
assert Sum(x,(x,1,10)).subs([(x,y-2)]) == Sum(x,(x,1,10))
assert Sum(1/x,(x,1,10)).subs([(x,(3+n)**3)]) == Sum(1/x,(x,1,10))
assert Sum(1/x,(x,1,10)).subs([(x,3*x-2)]) == Sum(1/x,(x,1,10))
def test_distribution_over_equality():
f = Function('f')
assert Product(Eq(x*2, f(x)), (x, 1, 3)).doit() == Eq(48, f(1)*f(2)*f(3))
assert Sum(Eq(f(x), x**2), (x, 0, y)) == \
Eq(Sum(f(x), (x, 0, y)), Sum(x**2, (x, 0, y)))
def test_issue_2787():
n, k = symbols('n k', positive=True, integer=True)
p = symbols('p', positive=True)
binomial_dist = binomial(n, k)*p**k*(1 - p)**(n - k)
s = Sum(binomial_dist*k, (k, 0, n))
res = s.doit().simplify()
assert res == Piecewise(
(n*p, p/Abs(p - 1) <= 1),
((-p + 1)**n*Sum(k*p**k*(-p + 1)**(-k)*binomial(n, k), (k, 0, n)),
True))
# Issue #17165: make sure that another simplify does not change/increase
# the result
assert res == res.simplify()
def test_issue_4668():
assert summation(1/n, (n, 2, oo)) is oo
def test_matrix_sum():
A = Matrix([[0, 1], [n, 0]])
result = Sum(A, (n, 0, 3)).doit()
assert result == Matrix([[0, 4], [6, 0]])
assert result.__class__ == ImmutableDenseMatrix
A = SparseMatrix([[0, 1], [n, 0]])
result = Sum(A, (n, 0, 3)).doit()
assert result.__class__ == ImmutableSparseMatrix
def test_failing_matrix_sum():
n = Symbol('n')
# TODO Implement matrix geometric series summation.
A = Matrix([[0, 1, 0], [-1, 0, 0], [0, 0, 0]])
assert Sum(A ** n, (n, 1, 4)).doit() == \
Matrix([[0, 0, 0], [0, 0, 0], [0, 0, 0]])
# issue sympy/sympy#16989
assert summation(A**n, (n, 1, 1)) == A
def test_indexed_idx_sum():
i = symbols('i', cls=Idx)
r = Indexed('r', i)
assert Sum(r, (i, 0, 3)).doit() == sum([r.xreplace({i: j}) for j in range(4)])
assert Product(r, (i, 0, 3)).doit() == prod([r.xreplace({i: j}) for j in range(4)])
j = symbols('j', integer=True)
assert Sum(r, (i, j, j+2)).doit() == sum([r.xreplace({i: j+k}) for k in range(3)])
assert Product(r, (i, j, j+2)).doit() == prod([r.xreplace({i: j+k}) for k in range(3)])
k = Idx('k', range=(1, 3))
A = IndexedBase('A')
assert Sum(A[k], k).doit() == sum([A[Idx(j, (1, 3))] for j in range(1, 4)])
assert Product(A[k], k).doit() == prod([A[Idx(j, (1, 3))] for j in range(1, 4)])
raises(ValueError, lambda: Sum(A[k], (k, 1, 4)))
raises(ValueError, lambda: Sum(A[k], (k, 0, 3)))
raises(ValueError, lambda: Sum(A[k], (k, 2, oo)))
raises(ValueError, lambda: Product(A[k], (k, 1, 4)))
raises(ValueError, lambda: Product(A[k], (k, 0, 3)))
raises(ValueError, lambda: Product(A[k], (k, 2, oo)))
def test_is_convergent():
# divergence tests --
assert Sum(n/(2*n + 1), (n, 1, oo)).is_convergent() is S.false
assert Sum(factorial(n)/5**n, (n, 1, oo)).is_convergent() is S.false
assert Sum(3**(-2*n - 1)*n**n, (n, 1, oo)).is_convergent() is S.false
assert Sum((-1)**n*n, (n, 3, oo)).is_convergent() is S.false
assert Sum((-1)**n, (n, 1, oo)).is_convergent() is S.false
assert Sum(log(1/n), (n, 2, oo)).is_convergent() is S.false
# Raabe's test --
assert Sum(Product((3*m),(m,1,n))/Product((3*m+4),(m,1,n)),(n,1,oo)).is_convergent() is S.true
# root test --
assert Sum((-12)**n/n, (n, 1, oo)).is_convergent() is S.false
# integral test --
# p-series test --
assert Sum(1/(n**2 + 1), (n, 1, oo)).is_convergent() is S.true
assert Sum(1/n**Rational(6, 5), (n, 1, oo)).is_convergent() is S.true
assert Sum(2/(n*sqrt(n - 1)), (n, 2, oo)).is_convergent() is S.true
assert Sum(1/(sqrt(n)*sqrt(n)), (n, 2, oo)).is_convergent() is S.false
assert Sum(factorial(n) / factorial(n+2), (n, 1, oo)).is_convergent() is S.true
assert Sum(rf(5,n)/rf(7,n),(n,1,oo)).is_convergent() is S.true
assert Sum((rf(1, n)*rf(2, n))/(rf(3, n)*factorial(n)),(n,1,oo)).is_convergent() is S.false
# comparison test --
assert Sum(1/(n + log(n)), (n, 1, oo)).is_convergent() is S.false
assert Sum(1/(n**2*log(n)), (n, 2, oo)).is_convergent() is S.true
assert Sum(1/(n*log(n)), (n, 2, oo)).is_convergent() is S.false
assert Sum(2/(n*log(n)*log(log(n))**2), (n, 5, oo)).is_convergent() is S.true
assert Sum(2/(n*log(n)**2), (n, 2, oo)).is_convergent() is S.true
assert Sum((n - 1)/(n**2*log(n)**3), (n, 2, oo)).is_convergent() is S.true
assert Sum(1/(n*log(n)*log(log(n))), (n, 5, oo)).is_convergent() is S.false
assert Sum((n - 1)/(n*log(n)**3), (n, 3, oo)).is_convergent() is S.false
assert Sum(2/(n**2*log(n)), (n, 2, oo)).is_convergent() is S.true
assert Sum(1/(n*sqrt(log(n))*log(log(n))), (n, 100, oo)).is_convergent() is S.false
assert Sum(log(log(n))/(n*log(n)**2), (n, 100, oo)).is_convergent() is S.true
assert Sum(log(n)/n**2, (n, 5, oo)).is_convergent() is S.true
# alternating series tests --
assert Sum((-1)**(n - 1)/(n**2 - 1), (n, 3, oo)).is_convergent() is S.true
# with -negativeInfinite Limits
assert Sum(1/(n**2 + 1), (n, -oo, 1)).is_convergent() is S.true
assert Sum(1/(n - 1), (n, -oo, -1)).is_convergent() is S.false
assert Sum(1/(n**2 - 1), (n, -oo, -5)).is_convergent() is S.true
assert Sum(1/(n**2 - 1), (n, -oo, 2)).is_convergent() is S.true
assert Sum(1/(n**2 - 1), (n, -oo, oo)).is_convergent() is S.true
# piecewise functions
f = Piecewise((n**(-2), n <= 1), (n**2, n > 1))
assert Sum(f, (n, 1, oo)).is_convergent() is S.false
assert Sum(f, (n, -oo, oo)).is_convergent() is S.false
assert Sum(f, (n, 1, 100)).is_convergent() is S.true
#assert Sum(f, (n, -oo, 1)).is_convergent() is S.true
# integral test
assert Sum(log(n)/n**3, (n, 1, oo)).is_convergent() is S.true
assert Sum(-log(n)/n**3, (n, 1, oo)).is_convergent() is S.true
# the following function has maxima located at (x, y) =
# (1.2, 0.43), (3.0, -0.25) and (6.8, 0.050)
eq = (x - 2)*(x**2 - 6*x + 4)*exp(-x)
assert Sum(eq, (x, 1, oo)).is_convergent() is S.true
assert Sum(eq, (x, 1, 2)).is_convergent() is S.true
assert Sum(1/(x**3), (x, 1, oo)).is_convergent() is S.true
assert Sum(1/(x**S.Half), (x, 1, oo)).is_convergent() is S.false
# issue 19545
assert Sum(1/n - 3/(3*n +2), (n, 1, oo)).is_convergent() is S.true
# issue 19836
assert Sum(4/(n + 2) - 5/(n + 1) + 1/n,(n, 7, oo)).is_convergent() is S.true
def test_is_absolutely_convergent():
assert Sum((-1)**n, (n, 1, oo)).is_absolutely_convergent() is S.false
assert Sum((-1)**n/n**2, (n, 1, oo)).is_absolutely_convergent() is S.true
@XFAIL
def test_convergent_failing():
# dirichlet tests
assert Sum(sin(n)/n, (n, 1, oo)).is_convergent() is S.true
assert Sum(sin(2*n)/n, (n, 1, oo)).is_convergent() is S.true
def test_issue_6966():
i, k, m = symbols('i k m', integer=True)
z_i, q_i = symbols('z_i q_i')
a_k = Sum(-q_i*z_i/k,(i,1,m))
b_k = a_k.diff(z_i)
assert isinstance(b_k, Sum)
assert b_k == Sum(-q_i/k,(i,1,m))
def test_issue_10156():
cx = Sum(2*y**2*x, (x, 1,3))
e = 2*y*Sum(2*cx*x**2, (x, 1, 9))
assert e.factor() == \
8*y**3*Sum(x, (x, 1, 3))*Sum(x**2, (x, 1, 9))
def test_issue_10973():
assert Sum((-n + (n**3 + 1)**(S(1)/3))/log(n), (n, 1, oo)).is_convergent() is S.true
def test_issue_14129():
assert Sum( k*x**k, (k, 0, n-1)).doit() == \
Piecewise((n**2/2 - n/2, Eq(x, 1)), ((n*x*x**n -
n*x**n - x*x**n + x)/(x - 1)**2, True))
assert Sum( x**k, (k, 0, n-1)).doit() == \
Piecewise((n, Eq(x, 1)), ((-x**n + 1)/(-x + 1), True))
assert Sum( k*(x/y+x)**k, (k, 0, n-1)).doit() == \
Piecewise((n*(n - 1)/2, Eq(x, y/(y + 1))),
(x*(y + 1)*(n*x*y*(x + x/y)**n/(x + x/y)
+ n*x*(x + x/y)**n/(x + x/y) - n*y*(x
+ x/y)**n/(x + x/y) - x*y*(x + x/y)**n/(x
+ x/y) - x*(x + x/y)**n/(x + x/y) + y)/(x*y
+ x - y)**2, True))
def test_issue_14112():
assert Sum((-1)**n/sqrt(n), (n, 1, oo)).is_absolutely_convergent() is S.false
assert Sum((-1)**(2*n)/n, (n, 1, oo)).is_convergent() is S.false
assert Sum((-2)**n + (-3)**n, (n, 1, oo)).is_convergent() is S.false
def test_sin_times_absolutely_convergent():
assert Sum(sin(n) / n**3, (n, 1, oo)).is_convergent() is S.true
assert Sum(sin(n) * log(n) / n**3, (n, 1, oo)).is_convergent() is S.true
def test_issue_14111():
assert Sum(1/log(log(n)), (n, 22, oo)).is_convergent() is S.false
def test_issue_14484():
assert Sum(sin(n)/log(log(n)), (n, 22, oo)).is_convergent() is S.false
def test_issue_14640():
i, n = symbols("i n", integer=True)
a, b, c = symbols("a b c")
assert Sum(a**-i/(a - b), (i, 0, n)).doit() == Sum(
1/(a*a**i - a**i*b), (i, 0, n)).doit() == Piecewise(
(n + 1, Eq(1/a, 1)),
((-a**(-n - 1) + 1)/(1 - 1/a), True))/(a - b)
assert Sum((b*a**i - c*a**i)**-2, (i, 0, n)).doit() == Piecewise(
(n + 1, Eq(a**(-2), 1)),
((-a**(-2*n - 2) + 1)/(1 - 1/a**2), True))/(b - c)**2
s = Sum(i*(a**(n - i) - b**(n - i))/(a - b), (i, 0, n)).doit()
assert not s.has(Sum)
assert s.subs({a: 2, b: 3, n: 5}) == 122
def test_issue_15943():
s = Sum(binomial(n, k)*factorial(n - k), (k, 0, n)).doit().rewrite(gamma)
assert s == -E*(n + 1)*gamma(n + 1)*lowergamma(n + 1, 1)/gamma(n + 2
) + E*gamma(n + 1)
assert s.simplify() == E*(factorial(n) - lowergamma(n + 1, 1))
def test_Sum_dummy_eq():
assert not Sum(x, (x, a, b)).dummy_eq(1)
assert not Sum(x, (x, a, b)).dummy_eq(Sum(x, (x, a, b), (a, 1, 2)))
assert not Sum(x, (x, a, b)).dummy_eq(Sum(x, (x, a, c)))
assert Sum(x, (x, a, b)).dummy_eq(Sum(x, (x, a, b)))
d = Dummy()
assert Sum(x, (x, a, d)).dummy_eq(Sum(x, (x, a, c)), c)
assert not Sum(x, (x, a, d)).dummy_eq(Sum(x, (x, a, c)))
assert Sum(x, (x, a, c)).dummy_eq(Sum(y, (y, a, c)))
assert Sum(x, (x, a, d)).dummy_eq(Sum(y, (y, a, c)), c)
assert not Sum(x, (x, a, d)).dummy_eq(Sum(y, (y, a, c)))
def test_issue_15852():
assert summation(x**y*y, (y, -oo, oo)).doit() == Sum(x**y*y, (y, -oo, oo))
def test_exceptions():
S = Sum(x, (x, a, b))
raises(ValueError, lambda: S.change_index(x, x**2, y))
S = Sum(x, (x, a, b), (x, 1, 4))
raises(ValueError, lambda: S.index(x))
S = Sum(x, (x, a, b), (y, 1, 4))
raises(ValueError, lambda: S.reorder([x]))
S = Sum(x, (x, y, b), (y, 1, 4))
raises(ReorderError, lambda: S.reorder_limit(0, 1))
S = Sum(x*y, (x, a, b), (y, 1, 4))
raises(NotImplementedError, lambda: S.is_convergent())
def test_sumproducts_assumptions():
M = Symbol('M', integer=True, positive=True)
m = Symbol('m', integer=True)
for func in [Sum, Product]:
assert func(m, (m, -M, M)).is_positive is None
assert func(m, (m, -M, M)).is_nonpositive is None
assert func(m, (m, -M, M)).is_negative is None
assert func(m, (m, -M, M)).is_nonnegative is None
assert func(m, (m, -M, M)).is_finite is True
m = Symbol('m', integer=True, nonnegative=True)
for func in [Sum, Product]:
assert func(m, (m, 0, M)).is_positive is None
assert func(m, (m, 0, M)).is_nonpositive is None
assert func(m, (m, 0, M)).is_negative is False
assert func(m, (m, 0, M)).is_nonnegative is True
assert func(m, (m, 0, M)).is_finite is True
m = Symbol('m', integer=True, positive=True)
for func in [Sum, Product]:
assert func(m, (m, 1, M)).is_positive is True
assert func(m, (m, 1, M)).is_nonpositive is False
assert func(m, (m, 1, M)).is_negative is False
assert func(m, (m, 1, M)).is_nonnegative is True
assert func(m, (m, 1, M)).is_finite is True
m = Symbol('m', integer=True, negative=True)
assert Sum(m, (m, -M, -1)).is_positive is False
assert Sum(m, (m, -M, -1)).is_nonpositive is True
assert Sum(m, (m, -M, -1)).is_negative is True
assert Sum(m, (m, -M, -1)).is_nonnegative is False
assert Sum(m, (m, -M, -1)).is_finite is True
assert Product(m, (m, -M, -1)).is_positive is None
assert Product(m, (m, -M, -1)).is_nonpositive is None
assert Product(m, (m, -M, -1)).is_negative is None
assert Product(m, (m, -M, -1)).is_nonnegative is None
assert Product(m, (m, -M, -1)).is_finite is True
m = Symbol('m', integer=True, nonpositive=True)
assert Sum(m, (m, -M, 0)).is_positive is False
assert Sum(m, (m, -M, 0)).is_nonpositive is True
assert Sum(m, (m, -M, 0)).is_negative is None
assert Sum(m, (m, -M, 0)).is_nonnegative is None
assert Sum(m, (m, -M, 0)).is_finite is True
assert Product(m, (m, -M, 0)).is_positive is None
assert Product(m, (m, -M, 0)).is_nonpositive is None
assert Product(m, (m, -M, 0)).is_negative is None
assert Product(m, (m, -M, 0)).is_nonnegative is None
assert Product(m, (m, -M, 0)).is_finite is True
m = Symbol('m', integer=True)
assert Sum(2, (m, 0, oo)).is_positive is None
assert Sum(2, (m, 0, oo)).is_nonpositive is None
assert Sum(2, (m, 0, oo)).is_negative is None
assert Sum(2, (m, 0, oo)).is_nonnegative is None
assert Sum(2, (m, 0, oo)).is_finite is None
assert Product(2, (m, 0, oo)).is_positive is None
assert Product(2, (m, 0, oo)).is_nonpositive is None
assert Product(2, (m, 0, oo)).is_negative is False
assert Product(2, (m, 0, oo)).is_nonnegative is None
assert Product(2, (m, 0, oo)).is_finite is None
assert Product(0, (x, M, M-1)).is_positive is True
assert Product(0, (x, M, M-1)).is_finite is True
def test_expand_with_assumptions():
M = Symbol('M', integer=True, positive=True)
x = Symbol('x', positive=True)
m = Symbol('m', nonnegative=True)
assert log(Product(x**m, (m, 0, M))).expand() == Sum(m*log(x), (m, 0, M))
assert log(Product(exp(x**m), (m, 0, M))).expand() == Sum(x**m, (m, 0, M))
assert log(Product(x**m, (m, 0, M))).rewrite(Sum).expand() == Sum(m*log(x), (m, 0, M))
assert log(Product(exp(x**m), (m, 0, M))).rewrite(Sum).expand() == Sum(x**m, (m, 0, M))
n = Symbol('n', nonnegative=True)
i, j = symbols('i,j', positive=True, integer=True)
x, y = symbols('x,y', positive=True)
assert log(Product(x**i*y**j, (i, 1, n), (j, 1, m))).expand() \
== Sum(i*log(x) + j*log(y), (i, 1, n), (j, 1, m))
def test_has_finite_limits():
x = Symbol('x')
assert Sum(1, (x, 1, 9)).has_finite_limits is True
assert Sum(1, (x, 1, oo)).has_finite_limits is False
M = Symbol('M')
assert Sum(1, (x, 1, M)).has_finite_limits is None
M = Symbol('M', positive=True)
assert Sum(1, (x, 1, M)).has_finite_limits is True
x = Symbol('x', positive=True)
M = Symbol('M')
assert Sum(1, (x, 1, M)).has_finite_limits is True
assert Sum(1, (x, 1, M), (y, -oo, oo)).has_finite_limits is False
def test_has_reversed_limits():
assert Sum(1, (x, 1, 1)).has_reversed_limits is False
assert Sum(1, (x, 1, 9)).has_reversed_limits is False
assert Sum(1, (x, 1, -9)).has_reversed_limits is True
assert Sum(1, (x, 1, 0)).has_reversed_limits is True
assert Sum(1, (x, 1, oo)).has_reversed_limits is False
M = Symbol('M')
assert Sum(1, (x, 1, M)).has_reversed_limits is None
M = Symbol('M', positive=True, integer=True)
assert Sum(1, (x, 1, M)).has_reversed_limits is False
assert Sum(1, (x, 1, M), (y, -oo, oo)).has_reversed_limits is False
M = Symbol('M', negative=True)
assert Sum(1, (x, 1, M)).has_reversed_limits is True
assert Sum(1, (x, 1, M), (y, -oo, oo)).has_reversed_limits is True
assert Sum(1, (x, oo, oo)).has_reversed_limits is None
def test_has_empty_sequence():
assert Sum(1, (x, 1, 1)).has_empty_sequence is False
assert Sum(1, (x, 1, 9)).has_empty_sequence is False
assert Sum(1, (x, 1, -9)).has_empty_sequence is False
assert Sum(1, (x, 1, 0)).has_empty_sequence is True
assert Sum(1, (x, y, y - 1)).has_empty_sequence is True
assert Sum(1, (x, 3, 2), (y, -oo, oo)).has_empty_sequence is True
assert Sum(1, (y, -oo, oo), (x, 3, 2)).has_empty_sequence is True
assert Sum(1, (x, oo, oo)).has_empty_sequence is False
def test_empty_sequence():
assert Product(x*y, (x, -oo, oo), (y, 1, 0)).doit() == 1
assert Product(x*y, (y, 1, 0), (x, -oo, oo)).doit() == 1
assert Sum(x, (x, -oo, oo), (y, 1, 0)).doit() == 0
assert Sum(x, (y, 1, 0), (x, -oo, oo)).doit() == 0
def test_issue_8016():
k = Symbol('k', integer=True)
n, m = symbols('n, m', integer=True, positive=True)
s = Sum(binomial(m, k)*binomial(m, n - k)*(-1)**k, (k, 0, n))
assert s.doit().simplify() == \
cos(pi*n/2)*gamma(m + 1)/gamma(n/2 + 1)/gamma(m - n/2 + 1)
def test_issue_14313():
assert Sum(S.Half**floor(n/2), (n, 1, oo)).is_convergent()
def test_issue_14563():
# The assertion was failing due to no assumptions methods in Sums and Product
assert 1 % Sum(1, (x, 0, 1)) == 1
def test_issue_16735():
assert Sum(5**n/gamma(n+1), (n, 1, oo)).is_convergent() is S.true
def test_issue_14871():
assert Sum((Rational(1, 10))**n*rf(0, n)/factorial(n), (n, 0, oo)).rewrite(factorial).doit() == 1
def test_issue_17165():
n = symbols("n", integer=True)
x = symbols('x')
s = (x*Sum(x**n, (n, -1, oo)))
ssimp = s.doit().simplify()
assert ssimp == Piecewise((-1/(x - 1), Abs(x) < 1),
(x*Sum(x**n, (n, -1, oo)), True))
assert ssimp == ssimp.simplify()
def test_issue_19379():
assert Sum(factorial(n)/factorial(n + 2), (n, 1, oo)).is_convergent() is S.true
def test_issue_20777():
assert Sum(exp(x*sin(n/m)), (n, 1, m)).doit() == Sum(exp(x*sin(n/m)), (n, 1, m))
def test__dummy_with_inherited_properties_concrete():
x = Symbol('x')
from sympy import Tuple
d = _dummy_with_inherited_properties_concrete(Tuple(x, 0, 5))
assert d.is_real
assert d.is_integer
assert d.is_nonnegative
assert d.is_extended_nonnegative
d = _dummy_with_inherited_properties_concrete(Tuple(x, 1, 9))
assert d.is_real
assert d.is_integer
assert d.is_positive
assert d.is_odd is None
d = _dummy_with_inherited_properties_concrete(Tuple(x, -5, 5))
assert d.is_real
assert d.is_integer
assert d.is_positive is None
assert d.is_extended_nonnegative is None
assert d.is_odd is None
d = _dummy_with_inherited_properties_concrete(Tuple(x, -1.5, 1.5))
assert d.is_real
assert d.is_integer is None
assert d.is_positive is None
assert d.is_extended_nonnegative is None
N = Symbol('N', integer=True, positive=True)
d = _dummy_with_inherited_properties_concrete(Tuple(x, 2, N))
assert d.is_real
assert d.is_positive
assert d.is_integer
# Return None if no assumptions are added
N = Symbol('N', integer=True, positive=True)
d = _dummy_with_inherited_properties_concrete(Tuple(N, 2, 4))
assert d is None
x = Symbol('x', negative=True)
raises(InconsistentAssumptions,
lambda: _dummy_with_inherited_properties_concrete(Tuple(x, 1, 5)))
def test_matrixsymbol_summation_numerical_limits():
A = MatrixSymbol('A', 3, 3)
n = Symbol('n', integer=True)
assert Sum(A**n, (n, 0, 2)).doit() == Identity(3) + A + A**2
assert Sum(A, (n, 0, 2)).doit() == 3*A
assert Sum(n*A, (n, 0, 2)).doit() == 3*A
B = Matrix([[0, n, 0], [-1, 0, 0], [0, 0, 2]])
ans = Matrix([[0, 6, 0], [-4, 0, 0], [0, 0, 8]]) + 4*A
assert Sum(A+B, (n, 0, 3)).doit() == ans
ans = A*Matrix([[0, 6, 0], [-4, 0, 0], [0, 0, 8]])
assert Sum(A*B, (n, 0, 3)).doit() == ans
ans = (A**2*Matrix([[-2, 0, 0], [0,-2, 0], [0, 0, 4]]) +
A**3*Matrix([[0, -9, 0], [3, 0, 0], [0, 0, 8]]) +
A*Matrix([[0, 1, 0], [-1, 0, 0], [0, 0, 2]]))
assert Sum(A**n*B**n, (n, 1, 3)).doit() == ans
@XFAIL
def test_matrixsymbol_summation_symbolic_limits():
N = Symbol('N', integer=True, positive=True)
A = MatrixSymbol('A', 3, 3)
n = Symbol('n', integer=True)
assert Sum(A, (n, 0, N)).doit() == (N+1)*A
assert Sum(n*A, (n, 0, N)).doit() == (N**2/2+N/2)*A
def test_summation_by_residues():
x = Symbol('x')
# Examples from Nakhle H. Asmar, Loukas Grafakos,
# Complex Analysis with Applications
assert eval_sum_residue(1 / (x**2 + 1), (x, -oo, oo)) == pi/tanh(pi)
assert eval_sum_residue(1 / x**6, (x, S(1), oo)) == pi**6/945
assert eval_sum_residue(1 / (x**2 + 9), (x, -oo, oo)) == pi/(3*tanh(3*pi))
assert eval_sum_residue(1 / (x**2 + 1)**2, (x, -oo, oo)).cancel() == \
(-pi**2*tanh(pi)**2 + pi*tanh(pi) + pi**2)/(2*tanh(pi)**2)
assert eval_sum_residue(x**2 / (x**2 + 1)**2, (x, -oo, oo)).cancel() == \
(-pi**2 + pi*tanh(pi) + pi**2*tanh(pi)**2)/(2*tanh(pi)**2)
assert eval_sum_residue(1 / (4*x**2 - 1), (x, -oo, oo)) == 0
assert eval_sum_residue(x**2 / (x**2 - S(1)/4)**2, (x, -oo, oo)) == pi**2/2
assert eval_sum_residue(1 / (4*x**2 - 1)**2, (x, -oo, oo)) == pi**2/8
assert eval_sum_residue(1 / ((x - S(1)/2)**2 + 1), (x, -oo, oo)) == pi*tanh(pi)
assert eval_sum_residue(1 / x**2, (x, S(1), oo)) == pi**2/6
assert eval_sum_residue(1 / x**4, (x, S(1), oo)) == pi**4/90
assert eval_sum_residue(1 / x**2 / (x**2 + 4), (x, S(1), oo)) == \
-pi*(-pi/12 - 1/(16*pi) + 1/(8*tanh(2*pi)))/2
# Some examples made from 1 / (x**2 + 1)
assert eval_sum_residue(1 / (x**2 + 1), (x, S(0), oo)) == \
S(1)/2 + pi/(2*tanh(pi))
assert eval_sum_residue(1 / (x**2 + 1), (x, S(1), oo)) == \
-S(1)/2 + pi/(2*tanh(pi))
assert eval_sum_residue(1 / (x**2 + 1), (x, S(-1), oo)) == \
1 + pi/(2*tanh(pi))
assert eval_sum_residue((-1)**x / (x**2 + 1), (x, -oo, oo)) == \
pi/sinh(pi)
assert eval_sum_residue((-1)**x / (x**2 + 1), (x, S(0), oo)) == \
pi/(2*sinh(pi)) + S(1)/2
assert eval_sum_residue((-1)**x / (x**2 + 1), (x, S(1), oo)) == \
-S(1)/2 + pi/(2*sinh(pi))
assert eval_sum_residue((-1)**x / (x**2 + 1), (x, S(-1), oo)) == \
pi/(2*sinh(pi))
# Some examples made from shifting of 1 / (x**2 + 1)
assert eval_sum_residue(1 / (x**2 + 2*x + 2), (x, S(-1), oo)) == S(1)/2 + pi/(2*tanh(pi))
assert eval_sum_residue(1 / (x**2 + 4*x + 5), (x, S(-2), oo)) == S(1)/2 + pi/(2*tanh(pi))
assert eval_sum_residue(1 / (x**2 - 2*x + 2), (x, S(1), oo)) == S(1)/2 + pi/(2*tanh(pi))
assert eval_sum_residue(1 / (x**2 - 4*x + 5), (x, S(2), oo)) == S(1)/2 + pi/(2*tanh(pi))
assert eval_sum_residue((-1)**x * -1 / (x**2 + 2*x + 2), (x, S(-1), oo)) == S(1)/2 + pi/(2*sinh(pi))
assert eval_sum_residue((-1)**x * -1 / (x**2 -2*x + 2), (x, S(1), oo)) == S(1)/2 + pi/(2*sinh(pi))
# Some examples made from 1 / x**2
assert eval_sum_residue(1 / x**2, (x, S(2), oo)) == -1 + pi**2/6
assert eval_sum_residue(1 / x**2, (x, S(3), oo)) == -S(5)/4 + pi**2/6
assert eval_sum_residue((-1)**x / x**2, (x, S(1), oo)) == -pi**2/12
assert eval_sum_residue((-1)**x / x**2, (x, S(2), oo)) == 1 - pi**2/12
def test_summation_by_residues_failing():
x = Symbol('x')
# Failing because of the bug in residue computation
assert eval_sum_residue(x**2 / (x**4 + 1), (x, S(1), oo))
assert eval_sum_residue(1 / ((x - 1)*(x - 2) + 1), (x, -oo, oo)) != 0
|
a134c65c0316af4e988be559f531a988a85b35be5d54957547e2810ddb413a05 | from sympy import Symbol, exp, log, oo, Rational, I, sin, gamma, loggamma, S, \
atan, acot, pi, cancel, E, erf, sqrt, zeta, cos, digamma, Integer, Ei, EulerGamma
from sympy.functions.elementary.hyperbolic import cosh, coth, sinh, tanh
from sympy.series.gruntz import compare, mrv, rewrite, mrv_leadterm, gruntz, \
sign
from sympy.testing.pytest import XFAIL, skip, slow
"""
This test suite is testing the limit algorithm using the bottom up approach.
See the documentation in limits2.py. The algorithm itself is highly recursive
by nature, so "compare" is logically the lowest part of the algorithm, yet in
some sense it's the most complex part, because it needs to calculate a limit
to return the result.
Nevertheless, the rest of the algorithm depends on compare working correctly.
"""
x = Symbol('x', real=True)
m = Symbol('m', real=True)
runslow = False
def _sskip():
if not runslow:
skip("slow")
@slow
def test_gruntz_evaluation():
# Gruntz' thesis pp. 122 to 123
# 8.1
assert gruntz(exp(x)*(exp(1/x - exp(-x)) - exp(1/x)), x, oo) == -1
# 8.2
assert gruntz(exp(x)*(exp(1/x + exp(-x) + exp(-x**2))
- exp(1/x - exp(-exp(x)))), x, oo) == 1
# 8.3
assert gruntz(exp(exp(x - exp(-x))/(1 - 1/x)) - exp(exp(x)), x, oo) is oo
# 8.5
assert gruntz(exp(exp(exp(x + exp(-x)))) / exp(exp(exp(x))), x, oo) is oo
# 8.6
assert gruntz(exp(exp(exp(x))) / exp(exp(exp(x - exp(-exp(x))))),
x, oo) is oo
# 8.7
assert gruntz(exp(exp(exp(x))) / exp(exp(exp(x - exp(-exp(exp(x)))))),
x, oo) == 1
# 8.8
assert gruntz(exp(exp(x)) / exp(exp(x - exp(-exp(exp(x))))), x, oo) == 1
# 8.9
assert gruntz(log(x)**2 * exp(sqrt(log(x))*(log(log(x)))**2
* exp(sqrt(log(log(x))) * (log(log(log(x))))**3)) / sqrt(x),
x, oo) == 0
# 8.10
assert gruntz((x*log(x)*(log(x*exp(x) - x**2))**2)
/ (log(log(x**2 + 2*exp(exp(3*x**3*log(x)))))), x, oo) == Rational(1, 3)
# 8.11
assert gruntz((exp(x*exp(-x)/(exp(-x) + exp(-2*x**2/(x + 1)))) - exp(x))/x,
x, oo) == -exp(2)
# 8.12
assert gruntz((3**x + 5**x)**(1/x), x, oo) == 5
# 8.13
assert gruntz(x/log(x**(log(x**(log(2)/log(x))))), x, oo) is oo
# 8.14
assert gruntz(exp(exp(2*log(x**5 + x)*log(log(x))))
/ exp(exp(10*log(x)*log(log(x)))), x, oo) is oo
# 8.15
assert gruntz(exp(exp(Rational(5, 2)*x**Rational(-5, 7) + Rational(21, 8)*x**Rational(6, 11)
+ 2*x**(-8) + Rational(54, 17)*x**Rational(49, 45)))**8
/ log(log(-log(Rational(4, 3)*x**Rational(-5, 14))))**Rational(7, 6), x, oo) is oo
# 8.16
assert gruntz((exp(4*x*exp(-x)/(1/exp(x) + 1/exp(2*x**2/(x + 1)))) - exp(x))
/ exp(x)**4, x, oo) == 1
# 8.17
assert gruntz(exp(x*exp(-x)/(exp(-x) + exp(-2*x**2/(x + 1))))/exp(x), x, oo) \
== 1
# 8.19
assert gruntz(log(x)*(log(log(x) + log(log(x))) - log(log(x)))
/ (log(log(x) + log(log(log(x))))), x, oo) == 1
# 8.20
assert gruntz(exp((log(log(x + exp(log(x)*log(log(x))))))
/ (log(log(log(exp(x) + x + log(x)))))), x, oo) == E
# Another
assert gruntz(exp(exp(exp(x + exp(-x)))) / exp(exp(x)), x, oo) is oo
def test_gruntz_evaluation_slow():
_sskip()
# 8.4
assert gruntz(exp(exp(exp(x)/(1 - 1/x)))
- exp(exp(exp(x)/(1 - 1/x - log(x)**(-log(x))))), x, oo) is -oo
# 8.18
assert gruntz((exp(exp(-x/(1 + exp(-x))))*exp(-x/(1 + exp(-x/(1 + exp(-x)))))
*exp(exp(-x + exp(-x/(1 + exp(-x))))))
/ (exp(-x/(1 + exp(-x))))**2 - exp(x) + x, x, oo) == 2
@slow
def test_gruntz_eval_special():
# Gruntz, p. 126
assert gruntz(exp(x)*(sin(1/x + exp(-x)) - sin(1/x + exp(-x**2))), x, oo) == 1
assert gruntz((erf(x - exp(-exp(x))) - erf(x)) * exp(exp(x)) * exp(x**2),
x, oo) == -2/sqrt(pi)
assert gruntz(exp(exp(x)) * (exp(sin(1/x + exp(-exp(x)))) - exp(sin(1/x))),
x, oo) == 1
assert gruntz(exp(x)*(gamma(x + exp(-x)) - gamma(x)), x, oo) is oo
assert gruntz(exp(exp(digamma(digamma(x))))/x, x, oo) == exp(Rational(-1, 2))
assert gruntz(exp(exp(digamma(log(x))))/x, x, oo) == exp(Rational(-1, 2))
assert gruntz(digamma(digamma(digamma(x))), x, oo) is oo
assert gruntz(loggamma(loggamma(x)), x, oo) is oo
assert gruntz(((gamma(x + 1/gamma(x)) - gamma(x))/log(x) - cos(1/x))
* x*log(x), x, oo) == Rational(-1, 2)
assert gruntz(x * (gamma(x - 1/gamma(x)) - gamma(x) + log(x)), x, oo) \
== S.Half
assert gruntz((gamma(x + 1/gamma(x)) - gamma(x)) / log(x), x, oo) == 1
def test_gruntz_eval_special_slow():
_sskip()
assert gruntz(gamma(x + 1)/sqrt(2*pi)
- exp(-x)*(x**(x + S.Half) + x**(x - S.Half)/12), x, oo) is oo
assert gruntz(exp(exp(exp(digamma(digamma(digamma(x))))))/x, x, oo) == 0
@XFAIL
def test_grunts_eval_special_slow_sometimes_fail():
_sskip()
# XXX This sometimes fails!!!
assert gruntz(exp(gamma(x - exp(-x))*exp(1/x)) - exp(gamma(x)), x, oo) is oo
@XFAIL
def test_gruntz_eval_special_fail():
# TODO exponential integral Ei
assert gruntz(
(Ei(x - exp(-exp(x))) - Ei(x)) *exp(-x)*exp(exp(x))*x, x, oo) == -1
# TODO zeta function series
assert gruntz(
exp((log(2) + 1)*x) * (zeta(x + exp(-x)) - zeta(x)), x, oo) == -log(2)
# TODO 8.35 - 8.37 (bessel, max-min)
def test_gruntz_hyperbolic():
assert gruntz(cosh(x), x, oo) is oo
assert gruntz(cosh(x), x, -oo) is oo
assert gruntz(sinh(x), x, oo) is oo
assert gruntz(sinh(x), x, -oo) is -oo
assert gruntz(2*cosh(x)*exp(x), x, oo) is oo
assert gruntz(2*cosh(x)*exp(x), x, -oo) == 1
assert gruntz(2*sinh(x)*exp(x), x, oo) is oo
assert gruntz(2*sinh(x)*exp(x), x, -oo) == -1
assert gruntz(tanh(x), x, oo) == 1
assert gruntz(tanh(x), x, -oo) == -1
assert gruntz(coth(x), x, oo) == 1
assert gruntz(coth(x), x, -oo) == -1
def test_compare1():
assert compare(2, x, x) == "<"
assert compare(x, exp(x), x) == "<"
assert compare(exp(x), exp(x**2), x) == "<"
assert compare(exp(x**2), exp(exp(x)), x) == "<"
assert compare(1, exp(exp(x)), x) == "<"
assert compare(x, 2, x) == ">"
assert compare(exp(x), x, x) == ">"
assert compare(exp(x**2), exp(x), x) == ">"
assert compare(exp(exp(x)), exp(x**2), x) == ">"
assert compare(exp(exp(x)), 1, x) == ">"
assert compare(2, 3, x) == "="
assert compare(3, -5, x) == "="
assert compare(2, -5, x) == "="
assert compare(x, x**2, x) == "="
assert compare(x**2, x**3, x) == "="
assert compare(x**3, 1/x, x) == "="
assert compare(1/x, x**m, x) == "="
assert compare(x**m, -x, x) == "="
assert compare(exp(x), exp(-x), x) == "="
assert compare(exp(-x), exp(2*x), x) == "="
assert compare(exp(2*x), exp(x)**2, x) == "="
assert compare(exp(x)**2, exp(x + exp(-x)), x) == "="
assert compare(exp(x), exp(x + exp(-x)), x) == "="
assert compare(exp(x**2), 1/exp(x**2), x) == "="
def test_compare2():
assert compare(exp(x), x**5, x) == ">"
assert compare(exp(x**2), exp(x)**2, x) == ">"
assert compare(exp(x), exp(x + exp(-x)), x) == "="
assert compare(exp(x + exp(-x)), exp(x), x) == "="
assert compare(exp(x + exp(-x)), exp(-x), x) == "="
assert compare(exp(-x), x, x) == ">"
assert compare(x, exp(-x), x) == "<"
assert compare(exp(x + 1/x), x, x) == ">"
assert compare(exp(-exp(x)), exp(x), x) == ">"
assert compare(exp(exp(-exp(x)) + x), exp(-exp(x)), x) == "<"
def test_compare3():
assert compare(exp(exp(x)), exp(x + exp(-exp(x))), x) == ">"
def test_sign1():
assert sign(Rational(0), x) == 0
assert sign(Rational(3), x) == 1
assert sign(Rational(-5), x) == -1
assert sign(log(x), x) == 1
assert sign(exp(-x), x) == 1
assert sign(exp(x), x) == 1
assert sign(-exp(x), x) == -1
assert sign(3 - 1/x, x) == 1
assert sign(-3 - 1/x, x) == -1
assert sign(sin(1/x), x) == 1
assert sign((x**Integer(2)), x) == 1
assert sign(x**2, x) == 1
assert sign(x**5, x) == 1
def test_sign2():
assert sign(x, x) == 1
assert sign(-x, x) == -1
y = Symbol("y", positive=True)
assert sign(y, x) == 1
assert sign(-y, x) == -1
assert sign(y*x, x) == 1
assert sign(-y*x, x) == -1
def mmrv(a, b):
return set(mrv(a, b)[0].keys())
def test_mrv1():
assert mmrv(x, x) == {x}
assert mmrv(x + 1/x, x) == {x}
assert mmrv(x**2, x) == {x}
assert mmrv(log(x), x) == {x}
assert mmrv(exp(x), x) == {exp(x)}
assert mmrv(exp(-x), x) == {exp(-x)}
assert mmrv(exp(x**2), x) == {exp(x**2)}
assert mmrv(-exp(1/x), x) == {x}
assert mmrv(exp(x + 1/x), x) == {exp(x + 1/x)}
def test_mrv2a():
assert mmrv(exp(x + exp(-exp(x))), x) == {exp(-exp(x))}
assert mmrv(exp(x + exp(-x)), x) == {exp(x + exp(-x)), exp(-x)}
assert mmrv(exp(1/x + exp(-x)), x) == {exp(-x)}
#sometimes infinite recursion due to log(exp(x**2)) not simplifying
def test_mrv2b():
assert mmrv(exp(x + exp(-x**2)), x) == {exp(-x**2)}
#sometimes infinite recursion due to log(exp(x**2)) not simplifying
def test_mrv2c():
assert mmrv(
exp(-x + 1/x**2) - exp(x + 1/x), x) == {exp(x + 1/x), exp(1/x**2 - x)}
#sometimes infinite recursion due to log(exp(x**2)) not simplifying
def test_mrv3():
assert mmrv(exp(x**2) + x*exp(x) + log(x)**x/x, x) == {exp(x**2)}
assert mmrv(
exp(x)*(exp(1/x + exp(-x)) - exp(1/x)), x) == {exp(x), exp(-x)}
assert mmrv(log(
x**2 + 2*exp(exp(3*x**3*log(x)))), x) == {exp(exp(3*x**3*log(x)))}
assert mmrv(log(x - log(x))/log(x), x) == {x}
assert mmrv(
(exp(1/x - exp(-x)) - exp(1/x))*exp(x), x) == {exp(x), exp(-x)}
assert mmrv(
1/exp(-x + exp(-x)) - exp(x), x) == {exp(x), exp(-x), exp(x - exp(-x))}
assert mmrv(log(log(x*exp(x*exp(x)) + 1)), x) == {exp(x*exp(x))}
assert mmrv(exp(exp(log(log(x) + 1/x))), x) == {x}
def test_mrv4():
ln = log
assert mmrv((ln(ln(x) + ln(ln(x))) - ln(ln(x)))/ln(ln(x) + ln(ln(ln(x))))*ln(x),
x) == {x}
assert mmrv(log(log(x*exp(x*exp(x)) + 1)) - exp(exp(log(log(x) + 1/x))), x) == \
{exp(x*exp(x))}
def mrewrite(a, b, c):
return rewrite(a[1], a[0], b, c)
def test_rewrite1():
e = exp(x)
assert mrewrite(mrv(e, x), x, m) == (1/m, -x)
e = exp(x**2)
assert mrewrite(mrv(e, x), x, m) == (1/m, -x**2)
e = exp(x + 1/x)
assert mrewrite(mrv(e, x), x, m) == (1/m, -x - 1/x)
e = 1/exp(-x + exp(-x)) - exp(x)
assert mrewrite(mrv(e, x), x, m) == (1/(m*exp(m)) - 1/m, -x)
def test_rewrite2():
e = exp(x)*log(log(exp(x)))
assert mmrv(e, x) == {exp(x)}
assert mrewrite(mrv(e, x), x, m) == (1/m*log(x), -x)
#sometimes infinite recursion due to log(exp(x**2)) not simplifying
def test_rewrite3():
e = exp(-x + 1/x**2) - exp(x + 1/x)
#both of these are correct and should be equivalent:
assert mrewrite(mrv(e, x), x, m) in [(-1/m + m*exp(
1/x + 1/x**2), -x - 1/x), (m - 1/m*exp(1/x + x**(-2)), x**(-2) - x)]
def test_mrv_leadterm1():
assert mrv_leadterm(-exp(1/x), x) == (-1, 0)
assert mrv_leadterm(1/exp(-x + exp(-x)) - exp(x), x) == (-1, 0)
assert mrv_leadterm(
(exp(1/x - exp(-x)) - exp(1/x))*exp(x), x) == (-exp(1/x), 0)
def test_mrv_leadterm2():
#Gruntz: p51, 3.25
assert mrv_leadterm((log(exp(x) + x) - x)/log(exp(x) + log(x))*exp(x), x) == \
(1, 0)
def test_mrv_leadterm3():
#Gruntz: p56, 3.27
assert mmrv(exp(-x + exp(-x)*exp(-x*log(x))), x) == {exp(-x - x*log(x))}
assert mrv_leadterm(exp(-x + exp(-x)*exp(-x*log(x))), x) == (exp(-x), 0)
def test_limit1():
assert gruntz(x, x, oo) is oo
assert gruntz(x, x, -oo) is -oo
assert gruntz(-x, x, oo) is -oo
assert gruntz(x**2, x, -oo) is oo
assert gruntz(-x**2, x, oo) is -oo
assert gruntz(x*log(x), x, 0, dir="+") == 0
assert gruntz(1/x, x, oo) == 0
assert gruntz(exp(x), x, oo) is oo
assert gruntz(-exp(x), x, oo) is -oo
assert gruntz(exp(x)/x, x, oo) is oo
assert gruntz(1/x - exp(-x), x, oo) == 0
assert gruntz(x + 1/x, x, oo) is oo
def test_limit2():
assert gruntz(x**x, x, 0, dir="+") == 1
assert gruntz((exp(x) - 1)/x, x, 0) == 1
assert gruntz(1 + 1/x, x, oo) == 1
assert gruntz(-exp(1/x), x, oo) == -1
assert gruntz(x + exp(-x), x, oo) is oo
assert gruntz(x + exp(-x**2), x, oo) is oo
assert gruntz(x + exp(-exp(x)), x, oo) is oo
assert gruntz(13 + 1/x - exp(-x), x, oo) == 13
def test_limit3():
a = Symbol('a')
assert gruntz(x - log(1 + exp(x)), x, oo) == 0
assert gruntz(x - log(a + exp(x)), x, oo) == 0
assert gruntz(exp(x)/(1 + exp(x)), x, oo) == 1
assert gruntz(exp(x)/(a + exp(x)), x, oo) == 1
def test_limit4():
#issue 3463
assert gruntz((3**x + 5**x)**(1/x), x, oo) == 5
#issue 3463
assert gruntz((3**(1/x) + 5**(1/x))**x, x, 0) == 5
@XFAIL
def test_MrvTestCase_page47_ex3_21():
h = exp(-x/(1 + exp(-x)))
expr = exp(h)*exp(-x/(1 + h))*exp(exp(-x + h))/h**2 - exp(x) + x
assert mmrv(expr, x) == {1/h, exp(-x), exp(x), exp(x - h), exp(x/(1 + h))}
def test_I():
from sympy import sign
y = Symbol("y")
assert gruntz(I*x, x, oo) == I*oo
assert gruntz(y*I*x, x, oo) == y*I*oo
assert gruntz(y*3*I*x, x, oo) == y*I*oo
assert gruntz(y*3*sin(I)*x, x, oo).simplify().rewrite(sign) == y*I*oo
def test_issue_4814():
assert gruntz((x + 1)**(1/log(x + 1)), x, oo) == E
def test_intractable():
assert gruntz(1/gamma(x), x, oo) == 0
assert gruntz(1/loggamma(x), x, oo) == 0
assert gruntz(gamma(x)/loggamma(x), x, oo) is oo
assert gruntz(exp(gamma(x))/gamma(x), x, oo) is oo
assert gruntz(gamma(x), x, 3) == 2
assert gruntz(gamma(Rational(1, 7) + 1/x), x, oo) == gamma(Rational(1, 7))
assert gruntz(log(x**x)/log(gamma(x)), x, oo) == 1
assert gruntz(log(gamma(gamma(x)))/exp(x), x, oo) is oo
def test_aseries_trig():
assert cancel(gruntz(1/log(atan(x)), x, oo)
- 1/(log(pi) + log(S.Half))) == 0
assert gruntz(1/acot(x), x, -oo) is -oo
def test_exp_log_series():
assert gruntz(x/log(log(x*exp(x))), x, oo) is oo
def test_issue_3644():
assert gruntz(((x**7 + x + 1)/(2**x + x**2))**(-1/x), x, oo) == 2
def test_issue_6843():
n = Symbol('n', integer=True, positive=True)
r = (n + 1)*x**(n + 1)/(x**(n + 1) - 1) - x/(x - 1)
assert gruntz(r, x, 1).simplify() == n/2
def test_issue_4190():
assert gruntz(x - gamma(1/x), x, oo) == S.EulerGamma
@XFAIL
def test_issue_5172():
n = Symbol('n')
r = Symbol('r', positive=True)
c = Symbol('c')
p = Symbol('p', positive=True)
m = Symbol('m', negative=True)
expr = ((2*n*(n - r + 1)/(n + r*(n - r + 1)))**c + \
(r - 1)*(n*(n - r + 2)/(n + r*(n - r + 1)))**c - n)/(n**c - n)
expr = expr.subs(c, c + 1)
assert gruntz(expr.subs(c, m), n, oo) == 1
# fail:
assert gruntz(expr.subs(c, p), n, oo).simplify() == \
(2**(p + 1) + r - 1)/(r + 1)**(p + 1)
def test_issue_4109():
assert gruntz(1/gamma(x), x, 0) == 0
assert gruntz(x*gamma(x), x, 0) == 1
def test_issue_6682():
assert gruntz(exp(2*Ei(-x))/x**2, x, 0) == exp(2*EulerGamma)
def test_issue_7096():
from sympy.functions import sign
assert gruntz(x**-pi, x, 0, dir='-') == oo*sign((-1)**(-pi))
|
a175718a55c7b2780f9e6e87e63c7db19641c6a654f47afd9e9edeea68dcb69a | from sympy import sin, cos, exp, E, series, oo, S, Derivative, O, Integral, \
Function, PoleError, log, sqrt, N, Symbol, Subs, pi, symbols, atan, LambertW, Rational
from sympy.abc import x, y, n, k
from sympy.testing.pytest import raises
from sympy.series.gruntz import calculate_series
def test_sin():
e1 = sin(x).series(x, 0)
e2 = series(sin(x), x, 0)
assert e1 == e2
def test_cos():
e1 = cos(x).series(x, 0)
e2 = series(cos(x), x, 0)
assert e1 == e2
def test_exp():
e1 = exp(x).series(x, 0)
e2 = series(exp(x), x, 0)
assert e1 == e2
def test_exp2():
e1 = exp(cos(x)).series(x, 0)
e2 = series(exp(cos(x)), x, 0)
assert e1 == e2
def test_issue_5223():
assert series(1, x) == 1
assert next(S.Zero.lseries(x)) == 0
assert cos(x).series() == cos(x).series(x)
raises(ValueError, lambda: cos(x + y).series())
raises(ValueError, lambda: x.series(dir=""))
assert (cos(x).series(x, 1) -
cos(x + 1).series(x).subs(x, x - 1)).removeO() == 0
e = cos(x).series(x, 1, n=None)
assert [next(e) for i in range(2)] == [cos(1), -((x - 1)*sin(1))]
e = cos(x).series(x, 1, n=None, dir='-')
assert [next(e) for i in range(2)] == [cos(1), (1 - x)*sin(1)]
# the following test is exact so no need for x -> x - 1 replacement
assert abs(x).series(x, 1, dir='-') == x
assert exp(x).series(x, 1, dir='-', n=3).removeO() == \
E - E*(-x + 1) + E*(-x + 1)**2/2
D = Derivative
assert D(x**2 + x**3*y**2, x, 2, y, 1).series(x).doit() == 12*x*y
assert next(D(cos(x), x).lseries()) == D(1, x)
assert D(
exp(x), x).series(n=3) == D(1, x) + D(x, x) + D(x**2/2, x) + D(x**3/6, x) + O(x**3)
assert Integral(x, (x, 1, 3), (y, 1, x)).series(x) == -4 + 4*x
assert (1 + x + O(x**2)).getn() == 2
assert (1 + x).getn() is None
raises(PoleError, lambda: ((1/sin(x))**oo).series())
logx = Symbol('logx')
assert ((sin(x))**y).nseries(x, n=1, logx=logx) == \
exp(y*logx) + O(x*exp(y*logx), x)
assert sin(1/x).series(x, oo, n=5) == 1/x - 1/(6*x**3) + O(x**(-5), (x, oo))
assert abs(x).series(x, oo, n=5, dir='+') == x
assert abs(x).series(x, -oo, n=5, dir='-') == -x
assert abs(-x).series(x, oo, n=5, dir='+') == x
assert abs(-x).series(x, -oo, n=5, dir='-') == -x
assert exp(x*log(x)).series(n=3) == \
1 + x*log(x) + x**2*log(x)**2/2 + O(x**3*log(x)**3)
# XXX is this right? If not, fix "ngot > n" handling in expr.
p = Symbol('p', positive=True)
assert exp(sqrt(p)**3*log(p)).series(n=3) == \
1 + p**S('3/2')*log(p) + O(p**3*log(p)**3)
assert exp(sin(x)*log(x)).series(n=2) == 1 + x*log(x) + O(x**2*log(x)**2)
def test_issue_11313():
assert Integral(cos(x), x).series(x) == sin(x).series(x)
assert Derivative(sin(x), x).series(x, n=3).doit() == cos(x).series(x, n=3)
assert Derivative(x**3, x).as_leading_term(x) == 3*x**2
assert Derivative(x**3, y).as_leading_term(x) == 0
assert Derivative(sin(x), x).as_leading_term(x) == 1
assert Derivative(cos(x), x).as_leading_term(x) == -x
# This result is equivalent to zero, zero is not return because
# `Expr.series` doesn't currently detect an `x` in its `free_symbol`s.
assert Derivative(1, x).as_leading_term(x) == Derivative(1, x)
assert Derivative(exp(x), x).series(x).doit() == exp(x).series(x)
assert 1 + Integral(exp(x), x).series(x) == exp(x).series(x)
assert Derivative(log(x), x).series(x).doit() == (1/x).series(x)
assert Integral(log(x), x).series(x) == Integral(log(x), x).doit().series(x).removeO()
def test_series_of_Subs():
from sympy.abc import x, y, z
subs1 = Subs(sin(x), x, y)
subs2 = Subs(sin(x) * cos(z), x, y)
subs3 = Subs(sin(x * z), (x, z), (y, x))
assert subs1.series(x) == subs1
subs1_series = (Subs(x, x, y) + Subs(-x**3/6, x, y) +
Subs(x**5/120, x, y) + O(y**6))
assert subs1.series() == subs1_series
assert subs1.series(y) == subs1_series
assert subs1.series(z) == subs1
assert subs2.series(z) == (Subs(z**4*sin(x)/24, x, y) +
Subs(-z**2*sin(x)/2, x, y) + Subs(sin(x), x, y) + O(z**6))
assert subs3.series(x).doit() == subs3.doit().series(x)
assert subs3.series(z).doit() == sin(x*y)
raises(ValueError, lambda: Subs(x + 2*y, y, z).series())
assert Subs(x + y, y, z).series(x).doit() == x + z
def test_issue_3978():
f = Function('f')
assert f(x).series(x, 0, 3, dir='-') == \
f(0) + x*Subs(Derivative(f(x), x), x, 0) + \
x**2*Subs(Derivative(f(x), x, x), x, 0)/2 + O(x**3)
assert f(x).series(x, 0, 3) == \
f(0) + x*Subs(Derivative(f(x), x), x, 0) + \
x**2*Subs(Derivative(f(x), x, x), x, 0)/2 + O(x**3)
assert f(x**2).series(x, 0, 3) == \
f(0) + x**2*Subs(Derivative(f(x), x), x, 0) + O(x**3)
assert f(x**2+1).series(x, 0, 3) == \
f(1) + x**2*Subs(Derivative(f(x), x), x, 1) + O(x**3)
class TestF(Function):
pass
assert TestF(x).series(x, 0, 3) == TestF(0) + \
x*Subs(Derivative(TestF(x), x), x, 0) + \
x**2*Subs(Derivative(TestF(x), x, x), x, 0)/2 + O(x**3)
from sympy.series.acceleration import richardson, shanks
from sympy import Sum, Integer
def test_acceleration():
e = (1 + 1/n)**n
assert round(richardson(e, n, 10, 20).evalf(), 10) == round(E.evalf(), 10)
A = Sum(Integer(-1)**(k + 1) / k, (k, 1, n))
assert round(shanks(A, n, 25).evalf(), 4) == round(log(2).evalf(), 4)
assert round(shanks(A, n, 25, 5).evalf(), 10) == round(log(2).evalf(), 10)
def test_issue_5852():
assert series(1/cos(x/log(x)), x, 0) == 1 + x**2/(2*log(x)**2) + \
5*x**4/(24*log(x)**4) + O(x**6)
def test_issue_4583():
assert cos(1 + x + x**2).series(x, 0, 5) == cos(1) - x*sin(1) + \
x**2*(-sin(1) - cos(1)/2) + x**3*(-cos(1) + sin(1)/6) + \
x**4*(-11*cos(1)/24 + sin(1)/2) + O(x**5)
def test_issue_6318():
eq = (1/x)**Rational(2, 3)
assert (eq + 1).as_leading_term(x) == eq
def test_x_is_base_detection():
eq = (x**2)**Rational(2, 3)
assert eq.series() == x**Rational(4, 3)
def test_sin_power():
e = sin(x)**1.2
assert calculate_series(e, x) == x**1.2
def test_issue_7203():
assert series(cos(x), x, pi, 3) == \
-1 + (x - pi)**2/2 + O((x - pi)**3, (x, pi))
def test_exp_product_positive_factors():
a, b = symbols('a, b', positive=True)
x = a * b
assert series(exp(x), x, n=8) == 1 + a*b + a**2*b**2/2 + \
a**3*b**3/6 + a**4*b**4/24 + a**5*b**5/120 + a**6*b**6/720 + \
a**7*b**7/5040 + O(a**8*b**8, a, b)
def test_issue_8805():
assert series(1, n=8) == 1
def test_issue_9549():
y = (x**2 + x + 1) / (x**3 + x**2)
assert series(y, x, oo) == x**(-5) - 1/x**4 + x**(-3) + 1/x + O(x**(-6), (x, oo))
def test_issue_10761():
assert series(1/(x**-2 + x**-3), x, 0) == x**3 - x**4 + x**5 + O(x**6)
def test_issue_12578():
y = (1 - 1/(x/2 - 1/(2*x))**4)**(S(1)/8)
assert y.series(x, 0, n=17) == 1 - 2*x**4 - 8*x**6 - 34*x**8 - 152*x**10 - 714*x**12 - \
3472*x**14 - 17318*x**16 + O(x**17)
def test_issue_12791():
beta = symbols('beta', real=True, positive=True)
theta, varphi = symbols('theta varphi', real=True)
expr = (-beta**2*varphi*sin(theta) + beta**2*cos(theta) + \
beta*varphi*sin(theta) - beta*cos(theta) - beta + 1)/(beta*cos(theta) - 1)**2
sol = 0.5/(0.5*cos(theta) - 1.0)**2 - 0.25*cos(theta)/(0.5*cos(theta)\
- 1.0)**2 + (beta - 0.5)*(-0.25*varphi*sin(2*theta) - 1.5*cos(theta)\
+ 0.25*cos(2*theta) + 1.25)/(0.5*cos(theta) - 1.0)**3\
+ 0.25*varphi*sin(theta)/(0.5*cos(theta) - 1.0)**2 + O((beta - 0.5)**2, (beta, 0.5))
assert expr.series(beta, 0.5, 2).trigsimp() == sol
def test_issue_14885():
assert series(x**Rational(-3, 2)*exp(x), x, 0) == (x**Rational(-3, 2) + 1/sqrt(x) +
sqrt(x)/2 + x**Rational(3, 2)/6 + x**Rational(5, 2)/24 + x**Rational(7, 2)/120 +
x**Rational(9, 2)/720 + x**Rational(11, 2)/5040 + O(x**6))
def test_issue_15539():
assert series(atan(x), x, -oo) == (-1/(5*x**5) + 1/(3*x**3) - 1/x - pi/2
+ O(x**(-6), (x, -oo)))
assert series(atan(x), x, oo) == (-1/(5*x**5) + 1/(3*x**3) - 1/x + pi/2
+ O(x**(-6), (x, oo)))
def test_issue_7259():
assert series(LambertW(x), x) == x - x**2 + 3*x**3/2 - 8*x**4/3 + 125*x**5/24 + O(x**6)
assert series(LambertW(x**2), x, n=8) == x**2 - x**4 + 3*x**6/2 + O(x**8)
assert series(LambertW(sin(x)), x, n=4) == x - x**2 + 4*x**3/3 + O(x**4)
def test_issue_11884():
assert cos(x).series(x, 1, n=1) == cos(1) + O(x - 1, (x, 1))
def test_issue_18008():
y = x*(1 + x*(1 - x))/((1 + x*(1 - x)) - (1 - x)*(1 - x))
assert y.series(x, oo, n=4) == -9/(32*x**3) - 3/(16*x**2) - 1/(8*x) + S(1)/4 + x/2 + \
O(x**(-4), (x, oo))
def test_issue_18842():
f = log(x/(1 - x))
assert f.series(x, 0.491, n=1).removeO().nsimplify() == \
-S(180019443780011)/5000000000000000
def test_issue_19534():
dt = symbols('dt', real=True)
expr = 16*dt*(0.125*dt*(2.0*dt + 1.0) + 0.875*dt + 1.0)/45 + \
49*dt*(-0.049335189898860408029*dt*(2.0*dt + 1.0) + \
0.29601113939316244817*dt*(0.125*dt*(2.0*dt + 1.0) + 0.875*dt + 1.0) - \
0.12564355335492979587*dt*(0.074074074074074074074*dt*(2.0*dt + 1.0) + \
0.2962962962962962963*dt*(0.125*dt*(2.0*dt + 1.0) + 0.875*dt + 1.0) + \
0.96296296296296296296*dt + 1.0) + 0.051640768506639183825*dt + \
dt*(1/2 - sqrt(21)/14) + 1.0)/180 + 49*dt*(-0.23637909581542530626*dt*(2.0*dt + 1.0) - \
0.74817562366625959291*dt*(0.125*dt*(2.0*dt + 1.0) + 0.875*dt + 1.0) + \
0.88085458023927036857*dt*(0.074074074074074074074*dt*(2.0*dt + 1.0) + \
0.2962962962962962963*dt*(0.125*dt*(2.0*dt + 1.0) + 0.875*dt + 1.0) + \
0.96296296296296296296*dt + 1.0) + \
2.1165151389911680013*dt*(-0.049335189898860408029*dt*(2.0*dt + 1.0) + \
0.29601113939316244817*dt*(0.125*dt*(2.0*dt + 1.0) + 0.875*dt + 1.0) - \
0.12564355335492979587*dt*(0.074074074074074074074*dt*(2.0*dt + 1.0) + \
0.2962962962962962963*dt*(0.125*dt*(2.0*dt + 1.0) + 0.875*dt + 1.0) + \
0.96296296296296296296*dt + 1.0) + 0.22431393315265061193*dt + 1.0) - \
1.1854881643947648988*dt + dt*(sqrt(21)/14 + 1/2) + 1.0)/180 + \
dt*(0.66666666666666666667*dt*(2.0*dt + 1.0) + \
6.0173399699313066769*dt*(0.125*dt*(2.0*dt + 1.0) + 0.875*dt + 1.0) - \
4.1117044797036320069*dt*(0.074074074074074074074*dt*(2.0*dt + 1.0) + \
0.2962962962962962963*dt*(0.125*dt*(2.0*dt + 1.0) + 0.875*dt + 1.0) + \
0.96296296296296296296*dt + 1.0) - \
7.0189140975801991157*dt*(-0.049335189898860408029*dt*(2.0*dt + 1.0) + \
0.29601113939316244817*dt*(0.125*dt*(2.0*dt + 1.0) + 0.875*dt + 1.0) - \
0.12564355335492979587*dt*(0.074074074074074074074*dt*(2.0*dt + 1.0) + \
0.2962962962962962963*dt*(0.125*dt*(2.0*dt + 1.0) + 0.875*dt + 1.0) + \
0.96296296296296296296*dt + 1.0) + 0.22431393315265061193*dt + 1.0) + \
0.94010945196161777522*dt*(-0.23637909581542530626*dt*(2.0*dt + 1.0) - \
0.74817562366625959291*dt*(0.125*dt*(2.0*dt + 1.0) + 0.875*dt + 1.0) + \
0.88085458023927036857*dt*(0.074074074074074074074*dt*(2.0*dt + 1.0) + \
0.2962962962962962963*dt*(0.125*dt*(2.0*dt + 1.0) + 0.875*dt + 1.0) + \
0.96296296296296296296*dt + 1.0) + \
2.1165151389911680013*dt*(-0.049335189898860408029*dt*(2.0*dt + 1.0) + \
0.29601113939316244817*dt*(0.125*dt*(2.0*dt + 1.0) + 0.875*dt + 1.0) - \
0.12564355335492979587*dt*(0.074074074074074074074*dt*(2.0*dt + 1.0) + \
0.2962962962962962963*dt*(0.125*dt*(2.0*dt + 1.0) + 0.875*dt + 1.0) + \
0.96296296296296296296*dt + 1.0) + 0.22431393315265061193*dt + 1.0) - \
0.35816132904077632692*dt + 1.0) + 5.5065024887242400038*dt + 1.0)/20 + dt/20 + 1
assert N(expr.series(dt, 0, 8), 20) == -0.00092592592592592596126*dt**7 + 0.0027777777777777783175*dt**6 + \
0.016666666666666656027*dt**5 + 0.083333333333333300952*dt**4 + 0.33333333333333337034*dt**3 + \
1.0*dt**2 + 1.0*dt + 1.0
def test_issue_11407():
a, b, c, x = symbols('a b c x')
assert series(sqrt(a + b + c*x), x, 0, 1) == sqrt(a + b) + O(x)
assert series(sqrt(a + b + c + c*x), x, 0, 1) == sqrt(a + b + c) + O(x)
def test_issue_14037():
assert (sin(x**50)/x**51).series(x, n=0) == 1/x + O(1, x)
def test_issue_20551():
expr = (exp(x)/x).series(x, n=None)
terms = [ next(expr) for i in range(3) ]
assert terms == [1/x, 1, x/2]
def test_issue_20697():
p_0, p_1, p_2, p_3, b_0, b_1, b_2 = symbols('p_0 p_1 p_2 p_3 b_0 b_1 b_2')
Q = (p_0 + (p_1 + (p_2 + p_3/y)/y)/y)/(1 + ((p_3/(b_0*y) + (b_0*p_2\
- b_1*p_3)/b_0**2)/y + (b_0**2*p_1 - b_0*b_1*p_2 - p_3*(b_0*b_2\
- b_1**2))/b_0**3)/y)
assert Q.series(y, n=3).ratsimp() == b_2*y**2 + b_1*y + b_0 + O(y**3)
def test_issue_21245():
fi = (1 + sqrt(5))/2
assert (1/(1 - x - x**2)).series(x, 1/fi, 1).factor() == \
(-6964*sqrt(5) - 15572 + 2440*sqrt(5)*x + 5456*x\
+ O((x - 2/(1 + sqrt(5)))**2, (x, 2/(1 + sqrt(5)))))/((1 + sqrt(5))**2\
*(20 + 9*sqrt(5))**2*(x + sqrt(5)*x - 2))
|
5dcb46c441142145120df22d892fe981a137f1e1e8ad36d04371c96298cfded4 | from sympy import (Symbol, Rational, Order, exp, ln, log, nan, oo, O, pi, I,
S, Integral, sin, cos, sqrt, conjugate, expand, transpose, symbols,
Function, Add)
from sympy.core.expr import unchanged
from sympy.testing.pytest import raises
from sympy.abc import w, x, y, z
def test_caching_bug():
#needs to be a first test, so that all caches are clean
#cache it
O(w)
#and test that this won't raise an exception
O(w**(-1/x/log(3)*log(5)), w)
def test_free_symbols():
assert Order(1).free_symbols == set()
assert Order(x).free_symbols == {x}
assert Order(1, x).free_symbols == {x}
assert Order(x*y).free_symbols == {x, y}
assert Order(x, x, y).free_symbols == {x, y}
def test_simple_1():
o = Rational(0)
assert Order(2*x) == Order(x)
assert Order(x)*3 == Order(x)
assert -28*Order(x) == Order(x)
assert Order(Order(x)) == Order(x)
assert Order(Order(x), y) == Order(Order(x), x, y)
assert Order(-23) == Order(1)
assert Order(exp(x)) == Order(1, x)
assert Order(exp(1/x)).expr == exp(1/x)
assert Order(x*exp(1/x)).expr == x*exp(1/x)
assert Order(x**(o/3)).expr == x**(o/3)
assert Order(x**(o*Rational(5, 3))).expr == x**(o*Rational(5, 3))
assert Order(x**2 + x + y, x) == O(1, x)
assert Order(x**2 + x + y, y) == O(1, y)
raises(ValueError, lambda: Order(exp(x), x, x))
raises(TypeError, lambda: Order(x, 2 - x))
def test_simple_2():
assert Order(2*x)*x == Order(x**2)
assert Order(2*x)/x == Order(1, x)
assert Order(2*x)*x*exp(1/x) == Order(x**2*exp(1/x))
assert (Order(2*x)*x*exp(1/x)/ln(x)**3).expr == x**2*exp(1/x)*ln(x)**-3
def test_simple_3():
assert Order(x) + x == Order(x)
assert Order(x) + 2 == 2 + Order(x)
assert Order(x) + x**2 == Order(x)
assert Order(x) + 1/x == 1/x + Order(x)
assert Order(1/x) + 1/x**2 == 1/x**2 + Order(1/x)
assert Order(x) + exp(1/x) == Order(x) + exp(1/x)
def test_simple_4():
assert Order(x)**2 == Order(x**2)
def test_simple_5():
assert Order(x) + Order(x**2) == Order(x)
assert Order(x) + Order(x**-2) == Order(x**-2)
assert Order(x) + Order(1/x) == Order(1/x)
def test_simple_6():
assert Order(x) - Order(x) == Order(x)
assert Order(x) + Order(1) == Order(1)
assert Order(x) + Order(x**2) == Order(x)
assert Order(1/x) + Order(1) == Order(1/x)
assert Order(x) + Order(exp(1/x)) == Order(exp(1/x))
assert Order(x**3) + Order(exp(2/x)) == Order(exp(2/x))
assert Order(x**-3) + Order(exp(2/x)) == Order(exp(2/x))
def test_simple_7():
assert 1 + O(1) == O(1)
assert 2 + O(1) == O(1)
assert x + O(1) == O(1)
assert 1/x + O(1) == 1/x + O(1)
def test_simple_8():
assert O(sqrt(-x)) == O(sqrt(x))
assert O(x**2*sqrt(x)) == O(x**Rational(5, 2))
assert O(x**3*sqrt(-(-x)**3)) == O(x**Rational(9, 2))
assert O(x**Rational(3, 2)*sqrt((-x)**3)) == O(x**3)
assert O(x*(-2*x)**(I/2)) == O(x*(-x)**(I/2))
def test_as_expr_variables():
assert Order(x).as_expr_variables(None) == (x, ((x, 0),))
assert Order(x).as_expr_variables(((x, 0),)) == (x, ((x, 0),))
assert Order(y).as_expr_variables(((x, 0),)) == (y, ((x, 0), (y, 0)))
assert Order(y).as_expr_variables(((x, 0), (y, 0))) == (y, ((x, 0), (y, 0)))
def test_contains_0():
assert Order(1, x).contains(Order(1, x))
assert Order(1, x).contains(Order(1))
assert Order(1).contains(Order(1, x)) is False
def test_contains_1():
assert Order(x).contains(Order(x))
assert Order(x).contains(Order(x**2))
assert not Order(x**2).contains(Order(x))
assert not Order(x).contains(Order(1/x))
assert not Order(1/x).contains(Order(exp(1/x)))
assert not Order(x).contains(Order(exp(1/x)))
assert Order(1/x).contains(Order(x))
assert Order(exp(1/x)).contains(Order(x))
assert Order(exp(1/x)).contains(Order(1/x))
assert Order(exp(1/x)).contains(Order(exp(1/x)))
assert Order(exp(2/x)).contains(Order(exp(1/x)))
assert not Order(exp(1/x)).contains(Order(exp(2/x)))
def test_contains_2():
assert Order(x).contains(Order(y)) is None
assert Order(x).contains(Order(y*x))
assert Order(y*x).contains(Order(x))
assert Order(y).contains(Order(x*y))
assert Order(x).contains(Order(y**2*x))
def test_contains_3():
assert Order(x*y**2).contains(Order(x**2*y)) is None
assert Order(x**2*y).contains(Order(x*y**2)) is None
def test_contains_4():
assert Order(sin(1/x**2)).contains(Order(cos(1/x**2))) is True
assert Order(cos(1/x**2)).contains(Order(sin(1/x**2))) is True
def test_contains():
assert Order(1, x) not in Order(1)
assert Order(1) in Order(1, x)
raises(TypeError, lambda: Order(x*y**2) in Order(x**2*y))
def test_add_1():
assert Order(x + x) == Order(x)
assert Order(3*x - 2*x**2) == Order(x)
assert Order(1 + x) == Order(1, x)
assert Order(1 + 1/x) == Order(1/x)
assert Order(ln(x) + 1/ln(x)) == Order(ln(x))
assert Order(exp(1/x) + x) == Order(exp(1/x))
assert Order(exp(1/x) + 1/x**20) == Order(exp(1/x))
def test_ln_args():
assert O(log(x)) + O(log(2*x)) == O(log(x))
assert O(log(x)) + O(log(x**3)) == O(log(x))
assert O(log(x*y)) + O(log(x) + log(y)) == O(log(x*y))
def test_multivar_0():
assert Order(x*y).expr == x*y
assert Order(x*y**2).expr == x*y**2
assert Order(x*y, x).expr == x
assert Order(x*y**2, y).expr == y**2
assert Order(x*y*z).expr == x*y*z
assert Order(x/y).expr == x/y
assert Order(x*exp(1/y)).expr == x*exp(1/y)
assert Order(exp(x)*exp(1/y)).expr == exp(x)*exp(1/y)
def test_multivar_0a():
assert Order(exp(1/x)*exp(1/y)).expr == exp(1/x)*exp(1/y)
def test_multivar_1():
assert Order(x + y).expr == x + y
assert Order(x + 2*y).expr == x + y
assert (Order(x + y) + x).expr == (x + y)
assert (Order(x + y) + x**2) == Order(x + y)
assert (Order(x + y) + 1/x) == 1/x + Order(x + y)
assert Order(x**2 + y*x).expr == x**2 + y*x
def test_multivar_2():
assert Order(x**2*y + y**2*x, x, y).expr == x**2*y + y**2*x
def test_multivar_mul_1():
assert Order(x + y)*x == Order(x**2 + y*x, x, y)
def test_multivar_3():
assert (Order(x) + Order(y)).args in [
(Order(x), Order(y)),
(Order(y), Order(x))]
assert Order(x) + Order(y) + Order(x + y) == Order(x + y)
assert (Order(x**2*y) + Order(y**2*x)).args in [
(Order(x*y**2), Order(y*x**2)),
(Order(y*x**2), Order(x*y**2))]
assert (Order(x**2*y) + Order(y*x)) == Order(x*y)
def test_issue_3468():
y = Symbol('y', negative=True)
z = Symbol('z', complex=True)
# check that Order does not modify assumptions about symbols
Order(x)
Order(y)
Order(z)
assert x.is_positive is None
assert y.is_positive is False
assert z.is_positive is None
def test_leading_order():
assert (x + 1 + 1/x**5).extract_leading_order(x) == ((1/x**5, O(1/x**5)),)
assert (1 + 1/x).extract_leading_order(x) == ((1/x, O(1/x)),)
assert (1 + x).extract_leading_order(x) == ((1, O(1, x)),)
assert (1 + x**2).extract_leading_order(x) == ((1, O(1, x)),)
assert (2 + x**2).extract_leading_order(x) == ((2, O(1, x)),)
assert (x + x**2).extract_leading_order(x) == ((x, O(x)),)
def test_leading_order2():
assert set((2 + pi + x**2).extract_leading_order(x)) == {(pi, O(1, x)),
(S(2), O(1, x))}
assert set((2*x + pi*x + x**2).extract_leading_order(x)) == {(2*x, O(x)),
(x*pi, O(x))}
def test_order_leadterm():
assert O(x**2)._eval_as_leading_term(x) == O(x**2)
def test_order_symbols():
e = x*y*sin(x)*Integral(x, (x, 1, 2))
assert O(e) == O(x**2*y, x, y)
assert O(e, x) == O(x**2)
def test_nan():
assert O(nan) is nan
assert not O(x).contains(nan)
def test_O1():
assert O(1, x) * x == O(x)
assert O(1, y) * x == O(1, y)
def test_getn():
# other lines are tested incidentally by the suite
assert O(x).getn() == 1
assert O(x/log(x)).getn() == 1
assert O(x**2/log(x)**2).getn() == 2
assert O(x*log(x)).getn() == 1
raises(NotImplementedError, lambda: (O(x) + O(y)).getn())
def test_diff():
assert O(x**2).diff(x) == O(x)
def test_getO():
assert (x).getO() is None
assert (x).removeO() == x
assert (O(x)).getO() == O(x)
assert (O(x)).removeO() == 0
assert (z + O(x) + O(y)).getO() == O(x) + O(y)
assert (z + O(x) + O(y)).removeO() == z
raises(NotImplementedError, lambda: (O(x) + O(y)).getn())
def test_leading_term():
from sympy import digamma
assert O(1/digamma(1/x)) == O(1/log(x))
def test_eval():
assert Order(x).subs(Order(x), 1) == 1
assert Order(x).subs(x, y) == Order(y)
assert Order(x).subs(y, x) == Order(x)
assert Order(x).subs(x, x + y) == Order(x + y, (x, -y))
assert (O(1)**x).is_Pow
def test_issue_4279():
a, b = symbols('a b')
assert O(a, a, b) + O(1, a, b) == O(1, a, b)
assert O(b, a, b) + O(1, a, b) == O(1, a, b)
assert O(a + b, a, b) + O(1, a, b) == O(1, a, b)
assert O(1, a, b) + O(a, a, b) == O(1, a, b)
assert O(1, a, b) + O(b, a, b) == O(1, a, b)
assert O(1, a, b) + O(a + b, a, b) == O(1, a, b)
def test_issue_4855():
assert 1/O(1) != O(1)
assert 1/O(x) != O(1/x)
assert 1/O(x, (x, oo)) != O(1/x, (x, oo))
f = Function('f')
assert 1/O(f(x)) != O(1/x)
def test_order_conjugate_transpose():
x = Symbol('x', real=True)
y = Symbol('y', imaginary=True)
assert conjugate(Order(x)) == Order(conjugate(x))
assert conjugate(Order(y)) == Order(conjugate(y))
assert conjugate(Order(x**2)) == Order(conjugate(x)**2)
assert conjugate(Order(y**2)) == Order(conjugate(y)**2)
assert transpose(Order(x)) == Order(transpose(x))
assert transpose(Order(y)) == Order(transpose(y))
assert transpose(Order(x**2)) == Order(transpose(x)**2)
assert transpose(Order(y**2)) == Order(transpose(y)**2)
def test_order_noncommutative():
A = Symbol('A', commutative=False)
assert Order(A + A*x, x) == Order(1, x)
assert (A + A*x)*Order(x) == Order(x)
assert (A*x)*Order(x) == Order(x**2, x)
assert expand((1 + Order(x))*A*A*x) == A*A*x + Order(x**2, x)
assert expand((A*A + Order(x))*x) == A*A*x + Order(x**2, x)
assert expand((A + Order(x))*A*x) == A*A*x + Order(x**2, x)
def test_issue_6753():
assert (1 + x**2)**10000*O(x) == O(x)
def test_order_at_infinity():
assert Order(1 + x, (x, oo)) == Order(x, (x, oo))
assert Order(3*x, (x, oo)) == Order(x, (x, oo))
assert Order(x, (x, oo))*3 == Order(x, (x, oo))
assert -28*Order(x, (x, oo)) == Order(x, (x, oo))
assert Order(Order(x, (x, oo)), (x, oo)) == Order(x, (x, oo))
assert Order(Order(x, (x, oo)), (y, oo)) == Order(x, (x, oo), (y, oo))
assert Order(3, (x, oo)) == Order(1, (x, oo))
assert Order(x**2 + x + y, (x, oo)) == O(x**2, (x, oo))
assert Order(x**2 + x + y, (y, oo)) == O(y, (y, oo))
assert Order(2*x, (x, oo))*x == Order(x**2, (x, oo))
assert Order(2*x, (x, oo))/x == Order(1, (x, oo))
assert Order(2*x, (x, oo))*x*exp(1/x) == Order(x**2*exp(1/x), (x, oo))
assert Order(2*x, (x, oo))*x*exp(1/x)/ln(x)**3 == Order(x**2*exp(1/x)*ln(x)**-3, (x, oo))
assert Order(x, (x, oo)) + 1/x == 1/x + Order(x, (x, oo)) == Order(x, (x, oo))
assert Order(x, (x, oo)) + 1 == 1 + Order(x, (x, oo)) == Order(x, (x, oo))
assert Order(x, (x, oo)) + x == x + Order(x, (x, oo)) == Order(x, (x, oo))
assert Order(x, (x, oo)) + x**2 == x**2 + Order(x, (x, oo))
assert Order(1/x, (x, oo)) + 1/x**2 == 1/x**2 + Order(1/x, (x, oo)) == Order(1/x, (x, oo))
assert Order(x, (x, oo)) + exp(1/x) == exp(1/x) + Order(x, (x, oo))
assert Order(x, (x, oo))**2 == Order(x**2, (x, oo))
assert Order(x, (x, oo)) + Order(x**2, (x, oo)) == Order(x**2, (x, oo))
assert Order(x, (x, oo)) + Order(x**-2, (x, oo)) == Order(x, (x, oo))
assert Order(x, (x, oo)) + Order(1/x, (x, oo)) == Order(x, (x, oo))
assert Order(x, (x, oo)) - Order(x, (x, oo)) == Order(x, (x, oo))
assert Order(x, (x, oo)) + Order(1, (x, oo)) == Order(x, (x, oo))
assert Order(x, (x, oo)) + Order(x**2, (x, oo)) == Order(x**2, (x, oo))
assert Order(1/x, (x, oo)) + Order(1, (x, oo)) == Order(1, (x, oo))
assert Order(x, (x, oo)) + Order(exp(1/x), (x, oo)) == Order(x, (x, oo))
assert Order(x**3, (x, oo)) + Order(exp(2/x), (x, oo)) == Order(x**3, (x, oo))
assert Order(x**-3, (x, oo)) + Order(exp(2/x), (x, oo)) == Order(exp(2/x), (x, oo))
# issue 7207
assert Order(exp(x), (x, oo)).expr == Order(2*exp(x), (x, oo)).expr == exp(x)
assert Order(y**x, (x, oo)).expr == Order(2*y**x, (x, oo)).expr == exp(log(y)*x)
# issue 19545
assert Order(1/x - 3/(3*x + 2), (x, oo)).expr == x**(-2)
def test_mixing_order_at_zero_and_infinity():
assert (Order(x, (x, 0)) + Order(x, (x, oo))).is_Add
assert Order(x, (x, 0)) + Order(x, (x, oo)) == Order(x, (x, oo)) + Order(x, (x, 0))
assert Order(Order(x, (x, oo))) == Order(x, (x, oo))
# not supported (yet)
raises(NotImplementedError, lambda: Order(x, (x, 0))*Order(x, (x, oo)))
raises(NotImplementedError, lambda: Order(x, (x, oo))*Order(x, (x, 0)))
raises(NotImplementedError, lambda: Order(Order(x, (x, oo)), y))
raises(NotImplementedError, lambda: Order(Order(x), (x, oo)))
def test_order_at_some_point():
assert Order(x, (x, 1)) == Order(1, (x, 1))
assert Order(2*x - 2, (x, 1)) == Order(x - 1, (x, 1))
assert Order(-x + 1, (x, 1)) == Order(x - 1, (x, 1))
assert Order(x - 1, (x, 1))**2 == Order((x - 1)**2, (x, 1))
assert Order(x - 2, (x, 2)) - O(x - 2, (x, 2)) == Order(x - 2, (x, 2))
def test_order_subs_limits():
# issue 3333
assert (1 + Order(x)).subs(x, 1/x) == 1 + Order(1/x, (x, oo))
assert (1 + Order(x)).limit(x, 0) == 1
# issue 5769
assert ((x + Order(x**2))/x).limit(x, 0) == 1
assert Order(x**2).subs(x, y - 1) == Order((y - 1)**2, (y, 1))
assert Order(10*x**2, (x, 2)).subs(x, y - 1) == Order(1, (y, 3))
def test_issue_9351():
assert exp(x).series(x, 10, 1) == exp(10) + Order(x - 10, (x, 10))
def test_issue_9192():
assert O(1)*O(1) == O(1)
assert O(1)**O(1) == O(1)
def test_issue_9910():
assert O(x*log(x) + sin(x), (x, oo)) == O(x*log(x), (x, oo))
def test_performance_of_adding_order():
l = list(x**i for i in range(1000))
l.append(O(x**1001))
assert Add(*l).subs(x,1) == O(1)
def test_issue_14622():
assert (x**(-4) + x**(-3) + x**(-1) + O(x**(-6), (x, oo))).as_numer_denom() == (
x**4 + x**5 + x**7 + O(x**2, (x, oo)), x**8)
assert (x**3 + O(x**2, (x, oo))).is_Add
assert O(x**2, (x, oo)).contains(x**3) is False
assert O(x, (x, oo)).contains(O(x, (x, 0))) is None
assert O(x, (x, 0)).contains(O(x, (x, oo))) is None
raises(NotImplementedError, lambda: O(x**3).contains(x**w))
def test_issue_15539():
assert O(1/x**2 + 1/x**4, (x, -oo)) == O(1/x**2, (x, -oo))
assert O(1/x**4 + exp(x), (x, -oo)) == O(1/x**4, (x, -oo))
assert O(1/x**4 + exp(-x), (x, -oo)) == O(exp(-x), (x, -oo))
assert O(1/x, (x, oo)).subs(x, -x) == O(-1/x, (x, -oo))
def test_issue_18606():
assert unchanged(Order, 0)
|
e9f5a05e87227681bd5fb886eafde2cc72ce7a086fc90af9f264583c6d428aab | from itertools import product as cartes
from sympy import (
limit, exp, oo, log, sqrt, Limit, sin, floor, cos, ceiling, sinh,
atan, Abs, gamma, Symbol, S, pi, Integral, Rational, I, E, besselj,
tan, cot, integrate, Sum, sign, Function, subfactorial, symbols,
binomial, simplify, frac, Float, sec, zoo, fresnelc, fresnels, real_root,
acos, erf, erfc, erfi, LambertW, factorial, digamma, uppergamma, re,
Ei, EulerGamma, asin, atanh, acot, acoth, asec, acsc, cbrt, besselk)
from sympy.calculus.util import AccumBounds
from sympy.core.mul import Mul
from sympy.series.limits import heuristics
from sympy.series.order import Order
from sympy.testing.pytest import XFAIL, raises
from sympy.abc import x, y, z, k
n = Symbol('n', integer=True, positive=True)
def test_basic1():
assert limit(x, x, oo) is oo
assert limit(x, x, -oo) is -oo
assert limit(-x, x, oo) is -oo
assert limit(x**2, x, -oo) is oo
assert limit(-x**2, x, oo) is -oo
assert limit(x*log(x), x, 0, dir="+") == 0
assert limit(1/x, x, oo) == 0
assert limit(exp(x), x, oo) is oo
assert limit(-exp(x), x, oo) is -oo
assert limit(exp(x)/x, x, oo) is oo
assert limit(1/x - exp(-x), x, oo) == 0
assert limit(x + 1/x, x, oo) is oo
assert limit(x - x**2, x, oo) is -oo
assert limit((1 + x)**(1 + sqrt(2)), x, 0) == 1
assert limit((1 + x)**oo, x, 0) == Limit((x + 1)**oo, x, 0)
assert limit((1 + x)**oo, x, 0, dir='-') == Limit((x + 1)**oo, x, 0, dir='-')
assert limit((1 + x + y)**oo, x, 0, dir='-') == Limit((1 + x + y)**oo, x, 0, dir='-')
assert limit(y/x/log(x), x, 0) == -oo*sign(y)
assert limit(cos(x + y)/x, x, 0) == sign(cos(y))*oo
assert limit(gamma(1/x + 3), x, oo) == 2
assert limit(S.NaN, x, -oo) is S.NaN
assert limit(Order(2)*x, x, S.NaN) is S.NaN
assert limit(1/(x - 1), x, 1, dir="+") is oo
assert limit(1/(x - 1), x, 1, dir="-") is -oo
assert limit(1/(5 - x)**3, x, 5, dir="+") is -oo
assert limit(1/(5 - x)**3, x, 5, dir="-") is oo
assert limit(1/sin(x), x, pi, dir="+") is -oo
assert limit(1/sin(x), x, pi, dir="-") is oo
assert limit(1/cos(x), x, pi/2, dir="+") is -oo
assert limit(1/cos(x), x, pi/2, dir="-") is oo
assert limit(1/tan(x**3), x, (2*pi)**Rational(1, 3), dir="+") is oo
assert limit(1/tan(x**3), x, (2*pi)**Rational(1, 3), dir="-") is -oo
assert limit(1/cot(x)**3, x, (pi*Rational(3, 2)), dir="+") is -oo
assert limit(1/cot(x)**3, x, (pi*Rational(3, 2)), dir="-") is oo
# test bi-directional limits
assert limit(sin(x)/x, x, 0, dir="+-") == 1
assert limit(x**2, x, 0, dir="+-") == 0
assert limit(1/x**2, x, 0, dir="+-") is oo
# test failing bi-directional limits
assert limit(1/x, x, 0, dir="+-") is zoo
# approaching 0
# from dir="+"
assert limit(1 + 1/x, x, 0) is oo
# from dir='-'
# Add
assert limit(1 + 1/x, x, 0, dir='-') is -oo
# Pow
assert limit(x**(-2), x, 0, dir='-') is oo
assert limit(x**(-3), x, 0, dir='-') is -oo
assert limit(1/sqrt(x), x, 0, dir='-') == (-oo)*I
assert limit(x**2, x, 0, dir='-') == 0
assert limit(sqrt(x), x, 0, dir='-') == 0
assert limit(x**-pi, x, 0, dir='-') == -oo*(-1)**(1 - pi)
assert limit((1 + cos(x))**oo, x, 0) == Limit((cos(x) + 1)**oo, x, 0)
def test_basic2():
assert limit(x**x, x, 0, dir="+") == 1
assert limit((exp(x) - 1)/x, x, 0) == 1
assert limit(1 + 1/x, x, oo) == 1
assert limit(-exp(1/x), x, oo) == -1
assert limit(x + exp(-x), x, oo) is oo
assert limit(x + exp(-x**2), x, oo) is oo
assert limit(x + exp(-exp(x)), x, oo) is oo
assert limit(13 + 1/x - exp(-x), x, oo) == 13
def test_basic3():
assert limit(1/x, x, 0, dir="+") is oo
assert limit(1/x, x, 0, dir="-") is -oo
def test_basic4():
assert limit(2*x + y*x, x, 0) == 0
assert limit(2*x + y*x, x, 1) == 2 + y
assert limit(2*x**8 + y*x**(-3), x, -2) == 512 - y/8
assert limit(sqrt(x + 1) - sqrt(x), x, oo) == 0
assert integrate(1/(x**3 + 1), (x, 0, oo)) == 2*pi*sqrt(3)/9
def test_log():
# https://github.com/sympy/sympy/issues/21598
a, b, c = symbols('a b c', positive=True)
A = log(a/b) - (log(a) - log(b))
assert A.limit(a, oo) == 0
assert (A * c).limit(a, oo) == 0
tau, x = symbols('tau x', positive=True)
# The value of manualintegrate in the issue
expr = tau**2*((tau - 1)*(tau + 1)*log(x + 1)/(tau**2 + 1)**2 + 1/((tau**2\
+ 1)*(x + 1)) - (-2*tau*atan(x/tau) + (tau**2/2 - 1/2)*log(tau**2\
+ x**2))/(tau**2 + 1)**2)
assert limit(expr, x, oo) == pi*tau**3/(tau**2 + 1)**2
def test_piecewise():
# https://github.com/sympy/sympy/issues/18363
assert limit((real_root(x - 6, 3) + 2)/(x + 2), x, -2, '+') == Rational(1, 12)
def test_basic5():
class my(Function):
@classmethod
def eval(cls, arg):
if arg is S.Infinity:
return S.NaN
assert limit(my(x), x, oo) == Limit(my(x), x, oo)
def test_issue_3885():
assert limit(x*y + x*z, z, 2) == x*y + 2*x
def test_Limit():
assert Limit(sin(x)/x, x, 0) != 1
assert Limit(sin(x)/x, x, 0).doit() == 1
assert Limit(x, x, 0, dir='+-').args == (x, x, 0, Symbol('+-'))
def test_floor():
assert limit(floor(x), x, -2, "+") == -2
assert limit(floor(x), x, -2, "-") == -3
assert limit(floor(x), x, -1, "+") == -1
assert limit(floor(x), x, -1, "-") == -2
assert limit(floor(x), x, 0, "+") == 0
assert limit(floor(x), x, 0, "-") == -1
assert limit(floor(x), x, 1, "+") == 1
assert limit(floor(x), x, 1, "-") == 0
assert limit(floor(x), x, 2, "+") == 2
assert limit(floor(x), x, 2, "-") == 1
assert limit(floor(x), x, 248, "+") == 248
assert limit(floor(x), x, 248, "-") == 247
# https://github.com/sympy/sympy/issues/14478
assert limit(x*floor(3/x)/2, x, 0, '+') == Rational(3, 2)
assert limit(floor(x + 1/2) - floor(x), x, oo) == AccumBounds(-0.5, 1.5)
def test_floor_requires_robust_assumptions():
assert limit(floor(sin(x)), x, 0, "+") == 0
assert limit(floor(sin(x)), x, 0, "-") == -1
assert limit(floor(cos(x)), x, 0, "+") == 0
assert limit(floor(cos(x)), x, 0, "-") == 0
assert limit(floor(5 + sin(x)), x, 0, "+") == 5
assert limit(floor(5 + sin(x)), x, 0, "-") == 4
assert limit(floor(5 + cos(x)), x, 0, "+") == 5
assert limit(floor(5 + cos(x)), x, 0, "-") == 5
def test_ceiling():
assert limit(ceiling(x), x, -2, "+") == -1
assert limit(ceiling(x), x, -2, "-") == -2
assert limit(ceiling(x), x, -1, "+") == 0
assert limit(ceiling(x), x, -1, "-") == -1
assert limit(ceiling(x), x, 0, "+") == 1
assert limit(ceiling(x), x, 0, "-") == 0
assert limit(ceiling(x), x, 1, "+") == 2
assert limit(ceiling(x), x, 1, "-") == 1
assert limit(ceiling(x), x, 2, "+") == 3
assert limit(ceiling(x), x, 2, "-") == 2
assert limit(ceiling(x), x, 248, "+") == 249
assert limit(ceiling(x), x, 248, "-") == 248
# https://github.com/sympy/sympy/issues/14478
assert limit(x*ceiling(3/x)/2, x, 0, '+') == Rational(3, 2)
assert limit(ceiling(x + 1/2) - ceiling(x), x, oo) == AccumBounds(-0.5, 1.5)
def test_ceiling_requires_robust_assumptions():
assert limit(ceiling(sin(x)), x, 0, "+") == 1
assert limit(ceiling(sin(x)), x, 0, "-") == 0
assert limit(ceiling(cos(x)), x, 0, "+") == 1
assert limit(ceiling(cos(x)), x, 0, "-") == 1
assert limit(ceiling(5 + sin(x)), x, 0, "+") == 6
assert limit(ceiling(5 + sin(x)), x, 0, "-") == 5
assert limit(ceiling(5 + cos(x)), x, 0, "+") == 6
assert limit(ceiling(5 + cos(x)), x, 0, "-") == 6
def test_atan():
x = Symbol("x", real=True)
assert limit(atan(x)*sin(1/x), x, 0) == 0
assert limit(atan(x) + sqrt(x + 1) - sqrt(x), x, oo) == pi/2
def test_set_signs():
assert limit(abs(x), x, 0) == 0
assert limit(abs(sin(x)), x, 0) == 0
assert limit(abs(cos(x)), x, 0) == 1
assert limit(abs(sin(x + 1)), x, 0) == sin(1)
# https://github.com/sympy/sympy/issues/9449
assert limit((Abs(x + y) - Abs(x - y))/(2*x), x, 0) == sign(y)
# https://github.com/sympy/sympy/issues/12398
assert limit(Abs(log(x)/x**3), x, oo) == 0
assert limit(x*(Abs(log(x)/x**3)/Abs(log(x + 1)/(x + 1)**3) - 1), x, oo) == 3
# https://github.com/sympy/sympy/issues/18501
assert limit(Abs(log(x - 1)**3 - 1), x, 1, '+') == oo
# https://github.com/sympy/sympy/issues/18997
assert limit(Abs(log(x)), x, 0) == oo
assert limit(Abs(log(Abs(x))), x, 0) == oo
# https://github.com/sympy/sympy/issues/19026
z = Symbol('z', positive=True)
assert limit(Abs(log(z) + 1)/log(z), z, oo) == 1
# https://github.com/sympy/sympy/issues/20704
assert limit(z*(Abs(1/z + y) - Abs(y - 1/z))/2, z, 0) == 0
# https://github.com/sympy/sympy/issues/21606
assert limit(cos(z)/sign(z), z, pi, '-') == -1
def test_heuristic():
x = Symbol("x", real=True)
assert heuristics(sin(1/x) + atan(x), x, 0, '+') == AccumBounds(-1, 1)
assert limit(log(2 + sqrt(atan(x))*sqrt(sin(1/x))), x, 0) == log(2)
def test_issue_3871():
z = Symbol("z", positive=True)
f = -1/z*exp(-z*x)
assert limit(f, x, oo) == 0
assert f.limit(x, oo) == 0
def test_exponential():
n = Symbol('n')
x = Symbol('x', real=True)
assert limit((1 + x/n)**n, n, oo) == exp(x)
assert limit((1 + x/(2*n))**n, n, oo) == exp(x/2)
assert limit((1 + x/(2*n + 1))**n, n, oo) == exp(x/2)
assert limit(((x - 1)/(x + 1))**x, x, oo) == exp(-2)
assert limit(1 + (1 + 1/x)**x, x, oo) == 1 + S.Exp1
assert limit((2 + 6*x)**x/(6*x)**x, x, oo) == exp(S('1/3'))
def test_exponential2():
n = Symbol('n')
assert limit((1 + x/(n + sin(n)))**n, n, oo) == exp(x)
def test_doit():
f = Integral(2 * x, x)
l = Limit(f, x, oo)
assert l.doit() is oo
def test_series_AccumBounds():
assert limit(sin(k) - sin(k + 1), k, oo) == AccumBounds(-2, 2)
assert limit(cos(k) - cos(k + 1) + 1, k, oo) == AccumBounds(-1, 3)
# not the exact bound
assert limit(sin(k) - sin(k)*cos(k), k, oo) == AccumBounds(-2, 2)
# test for issue #9934
t1 = Mul(AccumBounds(-S(3)/2 + cos(1)/2, cos(1)/2 + S.Half), 1/(-1 + cos(1)))
assert limit(simplify(Sum(cos(n).rewrite(exp), (n, 0, k)).doit().rewrite(sin)), k, oo) == t1
t2 = Mul(AccumBounds(-1 + sin(1)/2, sin(1)/2 + 1), 1/(1 - cos(1)))
assert limit(simplify(Sum(sin(n).rewrite(exp), (n, 0, k)).doit().rewrite(sin)), k, oo) == t2
assert limit(frac(x)**x, x, oo) == AccumBounds(0, oo) # wolfram gives (0, 1)
assert limit(((sin(x) + 1)/2)**x, x, oo) == AccumBounds(0, oo) # wolfram says 0
@XFAIL
def test_doit2():
f = Integral(2 * x, x)
l = Limit(f, x, oo)
# limit() breaks on the contained Integral.
assert l.doit(deep=False) == l
def test_issue_2929():
assert limit((x * exp(x))/(exp(x) - 1), x, -oo) == 0
def test_issue_3792():
assert limit((1 - cos(x))/x**2, x, S.Half) == 4 - 4*cos(S.Half)
assert limit(sin(sin(x + 1) + 1), x, 0) == sin(1 + sin(1))
assert limit(abs(sin(x + 1) + 1), x, 0) == 1 + sin(1)
def test_issue_4090():
assert limit(1/(x + 3), x, 2) == Rational(1, 5)
assert limit(1/(x + pi), x, 2) == S.One/(2 + pi)
assert limit(log(x)/(x**2 + 3), x, 2) == log(2)/7
assert limit(log(x)/(x**2 + pi), x, 2) == log(2)/(4 + pi)
def test_issue_4547():
assert limit(cot(x), x, 0, dir='+') is oo
assert limit(cot(x), x, pi/2, dir='+') == 0
def test_issue_5164():
assert limit(x**0.5, x, oo) == oo**0.5 is oo
assert limit(x**0.5, x, 16) == S(16)**0.5
assert limit(x**0.5, x, 0) == 0
assert limit(x**(-0.5), x, oo) == 0
assert limit(x**(-0.5), x, 4) == S(4)**(-0.5)
def test_issue_5383():
func = (1.0 * 1 + 1.0 * x)**(1.0 * 1 / x)
assert limit(func, x, 0) == E.n()
def test_issue_14793():
expr = ((x + S(1)/2) * log(x) - x + log(2*pi)/2 - \
log(factorial(x)) + S(1)/(12*x))*x**3
assert limit(expr, x, oo) == S(1)/360
def test_issue_5183():
# using list(...) so py.test can recalculate values
tests = list(cartes([x, -x],
[-1, 1],
[2, 3, S.Half, Rational(2, 3)],
['-', '+']))
results = (oo, oo, -oo, oo, -oo*I, oo, -oo*(-1)**Rational(1, 3), oo,
0, 0, 0, 0, 0, 0, 0, 0,
oo, oo, oo, -oo, oo, -oo*I, oo, -oo*(-1)**Rational(1, 3),
0, 0, 0, 0, 0, 0, 0, 0)
assert len(tests) == len(results)
for i, (args, res) in enumerate(zip(tests, results)):
y, s, e, d = args
eq = y**(s*e)
try:
assert limit(eq, x, 0, dir=d) == res
except AssertionError:
if 0: # change to 1 if you want to see the failing tests
print()
print(i, res, eq, d, limit(eq, x, 0, dir=d))
else:
assert None
def test_issue_5184():
assert limit(sin(x)/x, x, oo) == 0
assert limit(atan(x), x, oo) == pi/2
assert limit(gamma(x), x, oo) is oo
assert limit(cos(x)/x, x, oo) == 0
assert limit(gamma(x), x, S.Half) == sqrt(pi)
r = Symbol('r', real=True)
assert limit(r*sin(1/r), r, 0) == 0
def test_issue_5229():
assert limit((1 + y)**(1/y) - S.Exp1, y, 0) == 0
def test_issue_4546():
# using list(...) so py.test can recalculate values
tests = list(cartes([cot, tan],
[-pi/2, 0, pi/2, pi, pi*Rational(3, 2)],
['-', '+']))
results = (0, 0, -oo, oo, 0, 0, -oo, oo, 0, 0,
oo, -oo, 0, 0, oo, -oo, 0, 0, oo, -oo)
assert len(tests) == len(results)
for i, (args, res) in enumerate(zip(tests, results)):
f, l, d = args
eq = f(x)
try:
assert limit(eq, x, l, dir=d) == res
except AssertionError:
if 0: # change to 1 if you want to see the failing tests
print()
print(i, res, eq, l, d, limit(eq, x, l, dir=d))
else:
assert None
def test_issue_3934():
assert limit((1 + x**log(3))**(1/x), x, 0) == 1
assert limit((5**(1/x) + 3**(1/x))**x, x, 0) == 5
def test_calculate_series():
# needs gruntz calculate_series to go to n = 32
assert limit(x**Rational(77, 3)/(1 + x**Rational(77, 3)), x, oo) == 1
# needs gruntz calculate_series to go to n = 128
assert limit(x**101.1/(1 + x**101.1), x, oo) == 1
def test_issue_5955():
assert limit((x**16)/(1 + x**16), x, oo) == 1
assert limit((x**100)/(1 + x**100), x, oo) == 1
assert limit((x**1885)/(1 + x**1885), x, oo) == 1
assert limit((x**1000/((x + 1)**1000 + exp(-x))), x, oo) == 1
def test_newissue():
assert limit(exp(1/sin(x))/exp(cot(x)), x, 0) == 1
def test_extended_real_line():
assert limit(x - oo, x, oo) == Limit(x - oo, x, oo)
assert limit(1/(x + sin(x)) - oo, x, 0) == Limit(1/(x + sin(x)) - oo, x, 0)
assert limit(oo/x, x, oo) == Limit(oo/x, x, oo)
assert limit(x - oo + 1/x, x, oo) == Limit(x - oo + 1/x, x, oo)
@XFAIL
def test_order_oo():
x = Symbol('x', positive=True)
assert Order(x)*oo != Order(1, x)
assert limit(oo/(x**2 - 4), x, oo) is oo
def test_issue_5436():
raises(NotImplementedError, lambda: limit(exp(x*y), x, oo))
raises(NotImplementedError, lambda: limit(exp(-x*y), x, oo))
def test_Limit_dir():
raises(TypeError, lambda: Limit(x, x, 0, dir=0))
raises(ValueError, lambda: Limit(x, x, 0, dir='0'))
def test_polynomial():
assert limit((x + 1)**1000/((x + 1)**1000 + 1), x, oo) == 1
assert limit((x + 1)**1000/((x + 1)**1000 + 1), x, -oo) == 1
def test_rational():
assert limit(1/y - (1/(y + x) + x/(y + x)/y)/z, x, oo) == (z - 1)/(y*z)
assert limit(1/y - (1/(y + x) + x/(y + x)/y)/z, x, -oo) == (z - 1)/(y*z)
def test_issue_5740():
assert limit(log(x)*z - log(2*x)*y, x, 0) == oo*sign(y - z)
def test_issue_6366():
n = Symbol('n', integer=True, positive=True)
r = (n + 1)*x**(n + 1)/(x**(n + 1) - 1) - x/(x - 1)
assert limit(r, x, 1).cancel() == n/2
def test_factorial():
from sympy import factorial, E
f = factorial(x)
assert limit(f, x, oo) is oo
assert limit(x/f, x, oo) == 0
# see Stirling's approximation:
# https://en.wikipedia.org/wiki/Stirling's_approximation
assert limit(f/(sqrt(2*pi*x)*(x/E)**x), x, oo) == 1
assert limit(f, x, -oo) == factorial(-oo)
def test_issue_6560():
e = (5*x**3/4 - x*Rational(3, 4) + (y*(3*x**2/2 - S.Half) +
35*x**4/8 - 15*x**2/4 + Rational(3, 8))/(2*(y + 1)))
assert limit(e, y, oo) == 5*x**3/4 + 3*x**2/4 - 3*x/4 - Rational(1, 4)
@XFAIL
def test_issue_5172():
n = Symbol('n')
r = Symbol('r', positive=True)
c = Symbol('c')
p = Symbol('p', positive=True)
m = Symbol('m', negative=True)
expr = ((2*n*(n - r + 1)/(n + r*(n - r + 1)))**c +
(r - 1)*(n*(n - r + 2)/(n + r*(n - r + 1)))**c - n)/(n**c - n)
expr = expr.subs(c, c + 1)
raises(NotImplementedError, lambda: limit(expr, n, oo))
assert limit(expr.subs(c, m), n, oo) == 1
assert limit(expr.subs(c, p), n, oo).simplify() == \
(2**(p + 1) + r - 1)/(r + 1)**(p + 1)
def test_issue_7088():
a = Symbol('a')
assert limit(sqrt(x/(x + a)), x, oo) == 1
def test_branch_cuts():
assert limit(asin(I*x + 2), x, 0) == pi - asin(2)
assert limit(asin(I*x + 2), x, 0, '-') == asin(2)
assert limit(asin(I*x - 2), x, 0) == -asin(2)
assert limit(asin(I*x - 2), x, 0, '-') == -pi + asin(2)
assert limit(acos(I*x + 2), x, 0) == -acos(2)
assert limit(acos(I*x + 2), x, 0, '-') == acos(2)
assert limit(acos(I*x - 2), x, 0) == acos(-2)
assert limit(acos(I*x - 2), x, 0, '-') == 2*pi - acos(-2)
assert limit(atan(x + 2*I), x, 0) == I*atanh(2)
assert limit(atan(x + 2*I), x, 0, '-') == -pi + I*atanh(2)
assert limit(atan(x - 2*I), x, 0) == pi - I*atanh(2)
assert limit(atan(x - 2*I), x, 0, '-') == -I*atanh(2)
assert limit(atan(1/x), x, 0) == pi/2
assert limit(atan(1/x), x, 0, '-') == -pi/2
assert limit(atan(x), x, oo) == pi/2
assert limit(atan(x), x, -oo) == -pi/2
assert limit(acot(x + S(1)/2*I), x, 0) == pi - I*acoth(S(1)/2)
assert limit(acot(x + S(1)/2*I), x, 0, '-') == -I*acoth(S(1)/2)
assert limit(acot(x - S(1)/2*I), x, 0) == I*acoth(S(1)/2)
assert limit(acot(x - S(1)/2*I), x, 0, '-') == -pi + I*acoth(S(1)/2)
assert limit(acot(x), x, 0) == pi/2
assert limit(acot(x), x, 0, '-') == -pi/2
assert limit(asec(I*x + S(1)/2), x, 0) == asec(S(1)/2)
assert limit(asec(I*x + S(1)/2), x, 0, '-') == -asec(S(1)/2)
assert limit(asec(I*x - S(1)/2), x, 0) == 2*pi - asec(-S(1)/2)
assert limit(asec(I*x - S(1)/2), x, 0, '-') == asec(-S(1)/2)
assert limit(acsc(I*x + S(1)/2), x, 0) == acsc(S(1)/2)
assert limit(acsc(I*x + S(1)/2), x, 0, '-') == pi - acsc(S(1)/2)
assert limit(acsc(I*x - S(1)/2), x, 0) == -pi + acsc(S(1)/2)
assert limit(acsc(I*x - S(1)/2), x, 0, '-') == -acsc(S(1)/2)
assert limit(log(I*x - 1), x, 0) == I*pi
assert limit(log(I*x - 1), x, 0, '-') == -I*pi
assert limit(log(-I*x - 1), x, 0) == -I*pi
assert limit(log(-I*x - 1), x, 0, '-') == I*pi
assert limit(sqrt(I*x - 1), x, 0) == I
assert limit(sqrt(I*x - 1), x, 0, '-') == -I
assert limit(sqrt(-I*x - 1), x, 0) == -I
assert limit(sqrt(-I*x - 1), x, 0, '-') == I
assert limit(cbrt(I*x - 1), x, 0) == (-1)**(S(1)/3)
assert limit(cbrt(I*x - 1), x, 0, '-') == -(-1)**(S(2)/3)
assert limit(cbrt(-I*x - 1), x, 0) == -(-1)**(S(2)/3)
assert limit(cbrt(-I*x - 1), x, 0, '-') == (-1)**(S(1)/3)
def test_issue_6364():
a = Symbol('a')
e = z/(1 - sqrt(1 + z)*sin(a)**2 - sqrt(1 - z)*cos(a)**2)
assert limit(e, z, 0) == 1/(cos(a)**2 - S.Half)
def test_issue_4099():
a = Symbol('a')
assert limit(a/x, x, 0) == oo*sign(a)
assert limit(-a/x, x, 0) == -oo*sign(a)
assert limit(-a*x, x, oo) == -oo*sign(a)
assert limit(a*x, x, oo) == oo*sign(a)
def test_issue_4503():
dx = Symbol('dx')
assert limit((sqrt(1 + exp(x + dx)) - sqrt(1 + exp(x)))/dx, dx, 0) == \
exp(x)/(2*sqrt(exp(x) + 1))
def test_issue_8208():
assert limit(n**(Rational(1, 1e9) - 1), n, oo) == 0
def test_issue_8229():
assert limit((x**Rational(1, 4) - 2)/(sqrt(x) - 4)**Rational(2, 3), x, 16) == 0
def test_issue_8433():
d, t = symbols('d t', positive=True)
assert limit(erf(1 - t/d), t, oo) == -1
def test_issue_8481():
k = Symbol('k', integer=True, nonnegative=True)
lamda = Symbol('lamda', real=True, positive=True)
limit(lamda**k * exp(-lamda) / factorial(k), k, oo) == 0
def test_issue_8730():
assert limit(subfactorial(x), x, oo) is oo
def test_issue_9252():
n = Symbol('n', integer=True)
c = Symbol('c', positive=True)
assert limit((log(n))**(n/log(n)) / (1 + c)**n, n, oo) == 0
# limit should depend on the value of c
raises(NotImplementedError, lambda: limit((log(n))**(n/log(n)) / c**n, n, oo))
def test_issue_9558():
assert limit(sin(x)**15, x, 0, '-') == 0
def test_issue_10801():
# make sure limits work with binomial
assert limit(16**k / (k * binomial(2*k, k)**2), k, oo) == pi
def test_issue_10976():
s, x = symbols('s x', real=True)
assert limit(erf(s*x)/erf(s), s, 0) == x
def test_issue_9041():
assert limit(factorial(n) / ((n/exp(1))**n * sqrt(2*pi*n)), n, oo) == 1
def test_issue_9205():
x, y, a = symbols('x, y, a')
assert Limit(x, x, a).free_symbols == {a}
assert Limit(x, x, a, '-').free_symbols == {a}
assert Limit(x + y, x + y, a).free_symbols == {a}
assert Limit(-x**2 + y, x**2, a).free_symbols == {y, a}
def test_issue_9471():
assert limit(((27**(log(n,3)))/n**3),n,oo) == 1
assert limit(((27**(log(n,3)+1))/n**3),n,oo) == 27
def test_issue_11496():
assert limit(erfc(log(1/x)), x, oo) == 2
def test_issue_11879():
assert simplify(limit(((x+y)**n-x**n)/y, y, 0)) == n*x**(n-1)
def test_limit_with_Float():
k = symbols("k")
assert limit(1.0 ** k, k, oo) == 1
assert limit(0.3*1.0**k, k, oo) == Float(0.3)
def test_issue_10610():
assert limit(3**x*3**(-x - 1)*(x + 1)**2/x**2, x, oo) == Rational(1, 3)
def test_issue_6599():
assert limit((n + cos(n))/n, n, oo) == 1
def test_issue_12555():
assert limit((3**x + 2* x**10) / (x**10 + exp(x)), x, -oo) == 2
assert limit((3**x + 2* x**10) / (x**10 + exp(x)), x, oo) is oo
def test_issue_12769():
r, z, x = symbols('r z x', real=True)
a, b, s0, K, F0, s, T = symbols('a b s0 K F0 s T', positive=True, real=True)
fx = (F0**b*K**b*r*s0 - sqrt((F0**2*K**(2*b)*a**2*(b - 1) + \
F0**(2*b)*K**2*a**2*(b - 1) + F0**(2*b)*K**(2*b)*s0**2*(b - 1)*(b**2 - 2*b + 1) - \
2*F0**(2*b)*K**(b + 1)*a*r*s0*(b**2 - 2*b + 1) + \
2*F0**(b + 1)*K**(2*b)*a*r*s0*(b**2 - 2*b + 1) - \
2*F0**(b + 1)*K**(b + 1)*a**2*(b - 1))/((b - 1)*(b**2 - 2*b + 1))))*(b*r - b - r + 1)
assert fx.subs(K, F0).factor(deep=True) == limit(fx, K, F0).factor(deep=True)
def test_issue_13332():
assert limit(sqrt(30)*5**(-5*x - 1)*(46656*x)**x*(5*x + 2)**(5*x + 5*S.Half) *
(6*x + 2)**(-6*x - 5*S.Half), x, oo) == Rational(25, 36)
def test_issue_12564():
assert limit(x**2 + x*sin(x) + cos(x), x, -oo) is oo
assert limit(x**2 + x*sin(x) + cos(x), x, oo) is oo
assert limit(((x + cos(x))**2).expand(), x, oo) is oo
assert limit(((x + sin(x))**2).expand(), x, oo) is oo
assert limit(((x + cos(x))**2).expand(), x, -oo) is oo
assert limit(((x + sin(x))**2).expand(), x, -oo) is oo
def test_issue_14456():
raises(NotImplementedError, lambda: Limit(exp(x), x, zoo).doit())
raises(NotImplementedError, lambda: Limit(x**2/(x+1), x, zoo).doit())
def test_issue_14411():
assert limit(3*sec(4*pi*x - x/3), x, 3*pi/(24*pi - 2)) is -oo
def test_issue_13382():
assert limit(x*(((x + 1)**2 + 1)/(x**2 + 1) - 1), x, oo) == 2
def test_issue_13403():
assert limit(x*(-1 + (x + log(x + 1) + 1)/(x + log(x))), x ,oo) == 1
def test_issue_13416():
assert limit((-x**3*log(x)**3 + (x - 1)*(x + 1)**2*log(x + 1)**3)/(x**2*log(x)**3), x ,oo) == 1
def test_issue_13462():
assert limit(n**2*(2*n*(-(1 - 1/(2*n))**x + 1) - x - (-x**2/4 + x/4)/n), n, oo) == x**3/24 - x**2/8 + x/12
def test_issue_13750():
a = Symbol('a')
assert limit(erf(a - x), x, oo) == -1
assert limit(erf(sqrt(x) - x), x, oo) == -1
def test_issue_14514():
assert limit((1/(log(x)**log(x)))**(1/x), x, oo) == 1
def test_issue_14574():
assert limit(sqrt(x)*cos(x - x**2) / (x + 1), x, oo) == 0
def test_issue_10102():
assert limit(fresnels(x), x, oo) == S.Half
assert limit(3 + fresnels(x), x, oo) == 3 + S.Half
assert limit(5*fresnels(x), x, oo) == Rational(5, 2)
assert limit(fresnelc(x), x, oo) == S.Half
assert limit(fresnels(x), x, -oo) == Rational(-1, 2)
assert limit(4*fresnelc(x), x, -oo) == -2
def test_issue_14377():
raises(NotImplementedError, lambda: limit(exp(I*x)*sin(pi*x), x, oo))
def test_issue_15146():
e = (x/2) * (-2*x**3 - 2*(x**3 - 1) * x**2 * digamma(x**3 + 1) + \
2*(x**3 - 1) * x**2 * digamma(x**3 + x + 1) + x + 3)
assert limit(e, x, oo) == S(1)/3
def test_issue_15202():
e = (2**x*(2 + 2**(-x)*(-2*2**x + x + 2))/(x + 1))**(x + 1)
assert limit(e, x, oo) == exp(1)
e = (log(x, 2)**7 + 10*x*factorial(x) + 5**x) / (factorial(x + 1) + 3*factorial(x) + 10**x)
assert limit(e, x, oo) == 10
def test_issue_15282():
assert limit((x**2000 - (x + 1)**2000) / x**1999, x, oo) == -2000
def test_issue_15984():
assert limit((-x + log(exp(x) + 1))/x, x, oo, dir='-') == 0
def test_issue_13571():
assert limit(uppergamma(x, 1) / gamma(x), x, oo) == 1
def test_issue_13575():
assert limit(acos(erfi(x)), x, 1) == acos(erfi(S.One))
def test_issue_17325():
assert Limit(sin(x)/x, x, 0, dir="+-").doit() == 1
assert Limit(x**2, x, 0, dir="+-").doit() == 0
assert Limit(1/x**2, x, 0, dir="+-").doit() is oo
assert Limit(1/x, x, 0, dir="+-").doit() is zoo
def test_issue_10978():
assert LambertW(x).limit(x, 0) == 0
def test_issue_14313_comment():
assert limit(floor(n/2), n, oo) is oo
@XFAIL
def test_issue_15323():
d = ((1 - 1/x)**x).diff(x)
assert limit(d, x, 1, dir='+') == 1
def test_issue_12571():
assert limit(-LambertW(-log(x))/log(x), x, 1) == 1
def test_issue_14590():
assert limit((x**3*((x + 1)/x)**x)/((x + 1)*(x + 2)*(x + 3)), x, oo) == exp(1)
def test_issue_14393():
a, b = symbols('a b')
assert limit((x**b - y**b)/(x**a - y**a), x, y) == b*y**(-a + b)/a
def test_issue_14556():
assert limit(factorial(n + 1)**(1/(n + 1)) - factorial(n)**(1/n), n, oo) == exp(-1)
def test_issue_14811():
assert limit(((1 + ((S(2)/3)**(x + 1)))**(2**x))/(2**((S(4)/3)**(x - 1))), x, oo) == oo
def test_issue_14874():
assert limit(besselk(0, x), x, oo) == 0
def test_issue_16222():
assert limit(exp(x), x, 1000000000) == exp(1000000000)
def test_issue_16714():
assert limit(((x**(x + 1) + (x + 1)**x) / x**(x + 1))**x, x, oo) == exp(exp(1))
def test_issue_16722():
z = symbols('z', positive=True)
assert limit(binomial(n + z, n)*n**-z, n, oo) == 1/gamma(z + 1)
z = symbols('z', positive=True, integer=True)
assert limit(binomial(n + z, n)*n**-z, n, oo) == 1/gamma(z + 1)
def test_issue_17431():
assert limit(((n + 1) + 1) / (((n + 1) + 2) * factorial(n + 1)) *
(n + 2) * factorial(n) / (n + 1), n, oo) == 0
assert limit((n + 2)**2*factorial(n)/((n + 1)*(n + 3)*factorial(n + 1))
, n, oo) == 0
assert limit((n + 1) * factorial(n) / (n * factorial(n + 1)), n, oo) == 0
def test_issue_17671():
assert limit(Ei(-log(x)) - log(log(x))/x, x, 1) == EulerGamma
def test_issue_17751():
a, b, c, x = symbols('a b c x', positive=True)
assert limit((a + 1)*x - sqrt((a + 1)**2*x**2 + b*x + c), x, oo) == -b/(2*a + 2)
def test_issue_17792():
assert limit(factorial(n)/sqrt(n)*(exp(1)/n)**n, n, oo) == sqrt(2)*sqrt(pi)
def test_issue_18118():
assert limit(sign(sin(x)), x, 0, "-") == -1
assert limit(sign(sin(x)), x, 0, "+") == 1
def test_issue_18306():
assert limit(sin(sqrt(x))/sqrt(sin(x)), x, 0, '+') == 1
def test_issue_18378():
assert limit(log(exp(3*x) + x)/log(exp(x) + x**100), x, oo) == 3
def test_issue_18399():
assert limit((1 - S(1)/2*x)**(3*x), x, oo) is zoo
assert limit((-x)**x, x, oo) is zoo
def test_issue_18442():
assert limit(tan(x)**(2**(sqrt(pi))), x, oo, dir='-') == Limit(tan(x)**(2**(sqrt(pi))), x, oo, dir='-')
def test_issue_18452():
assert limit(abs(log(x))**x, x, 0) == 1
assert limit(abs(log(x))**x, x, 0, "-") == 1
def test_issue_18482():
assert limit((2*exp(3*x)/(exp(2*x) + 1))**(1/x), x, oo) == exp(1)
def test_issue_18508():
assert limit(sin(x)/sqrt(1-cos(x)), x, 0) == sqrt(2)
assert limit(sin(x)/sqrt(1-cos(x)), x, 0, dir='+') == sqrt(2)
assert limit(sin(x)/sqrt(1-cos(x)), x, 0, dir='-') == -sqrt(2)
def test_issue_18969():
a, b = symbols('a b', positive=True)
assert limit(LambertW(a), a, b) == LambertW(b)
assert limit(exp(LambertW(a)), a, b) == exp(LambertW(b))
def test_issue_18992():
assert limit(n/(factorial(n)**(1/n)), n, oo) == exp(1)
def test_issue_19067():
x = Symbol('x')
assert limit(gamma(x)/(gamma(x - 1)*gamma(x + 2)), x, 0) == -1
def test_issue_19586():
assert limit(x**(2**x*3**(-x)), x, oo) == 1
def test_issue_13715():
n = Symbol('n')
p = Symbol('p', zero=True)
assert limit(n + p, n, 0) == 0
def test_issue_15055():
assert limit(n**3*((-n - 1)*sin(1/n) + (n + 2)*sin(1/(n + 1)))/(-n + 1), n, oo) == 1
def test_issue_16708():
m, vi = symbols('m vi', positive=True)
B, ti, d = symbols('B ti d')
assert limit((B*ti*vi - sqrt(m)*sqrt(-2*B*d*vi + m*(vi)**2) + m*vi)/(B*vi), B, 0) == (d + ti*vi)/vi
def test_issue_19739():
assert limit((-S(1)/4)**x, x, oo) == 0
def test_issue_19766():
assert limit(2**(-x)*sqrt(4**(x + 1) + 1), x, oo) == 2
def test_issue_19770():
m = Symbol('m')
# the result is not 0 for non-real m
assert limit(cos(m*x)/x, x, oo) == Limit(cos(m*x)/x, x, oo, dir='-')
m = Symbol('m', real=True)
# can be improved to give the correct result 0
assert limit(cos(m*x)/x, x, oo) == Limit(cos(m*x)/x, x, oo, dir='-')
m = Symbol('m', nonzero=True)
assert limit(cos(m*x), x, oo) == AccumBounds(-1, 1)
assert limit(cos(m*x)/x, x, oo) == 0
def test_issue_7535():
assert limit(tan(x)/sin(tan(x)), x, pi/2) == Limit(tan(x)/sin(tan(x)), x, pi/2, dir='+')
assert limit(tan(x)/sin(tan(x)), x, pi/2, dir='-') == Limit(tan(x)/sin(tan(x)), x, pi/2, dir='-')
assert limit(tan(x)/sin(tan(x)), x, pi/2, dir='+-') == Limit(tan(x)/sin(tan(x)), x, pi/2, dir='+-')
assert limit(sin(tan(x)),x,pi/2) == AccumBounds(-1, 1)
assert -oo*(1/sin(-oo)) == AccumBounds(-oo, oo)
assert oo*(1/sin(oo)) == AccumBounds(-oo, oo)
assert oo*(1/sin(-oo)) == AccumBounds(-oo, oo)
assert -oo*(1/sin(oo)) == AccumBounds(-oo, oo)
def test_issue_20365():
assert limit(((x + 1)**(1/x) - E)/x, x, 0) == -E/2
def test_issue_21031():
assert limit(((1 + x)**(1/x) - (1 + 2*x)**(1/(2*x)))/asin(x), x, 0) == E/2
def test_issue_21038():
assert limit(sin(pi*x)/(3*x - 12), x, 4) == pi/3
def test_issue_20578():
expr = abs(x) * sin(1/x)
assert limit(expr,x,0,'+') == 0
assert limit(expr,x,0,'-') == 0
assert limit(expr,x,0,'+-') == 0
def test_issue_21415():
exp = (x-1)*cos(1/(x-1))
assert exp.limit(x,1) == 0
assert exp.expand().limit(x,1) == 0
def test_issue_21530():
assert limit(sinh(n + 1)/sinh(n), n, oo) == E
def test_issue_21550():
r = (sqrt(5) - 1)/2
assert limit((x - r)/(x**2 + x - 1), x, r) == sqrt(5)/5
def test_issue_21661():
out = limit((x**(x + 1) * (log(x) + 1) + 1) / x, x, 11)
assert out == S(3138428376722)/11 + 285311670611*log(11)
def test_issue_21701():
assert limit((besselj(z, x)/x**z).subs(z, 7), x, 0) == S(1)/645120
def test_issue_21721():
a = Symbol('a', real=True)
I = integrate(1/(pi*(1 + (x - a)**2)), x)
assert I.limit(x, oo) == S.Half
def test_issue_21756():
term = (1 - exp(-2*I*pi*z))/(1 - exp(-2*I*pi*z/5))
assert term.limit(z, 0) == 5
assert re(term).limit(z, 0) == 5
def test_issue_21785():
a = Symbol('a')
assert sqrt((-a**2 + x**2)/(1 - x**2)).limit(a, 1, '-') == I
|
7d422a533d81c9f6aa8d251513290104e9c620b92f07ed6dcb0c106859325ee0 | from sympy import (Symbol, exp, log, sqrt, O, oo, sin, cos, PoleError)
from sympy.abc import x
from sympy.testing.pytest import raises
def test_simple():
# Gruntz' theses pp. 91 to 96
# 6.6
e = sin(1/x + exp(-x)) - sin(1/x)
assert e.aseries(x) == (1/(24*x**4) - 1/(2*x**2) + 1 + O(x**(-6), (x, oo)))*exp(-x)
e = exp(x) * (exp(1/x + exp(-x)) - exp(1/x))
assert e.aseries(x, n=4) == 1/(6*x**3) + 1/(2*x**2) + 1/x + 1 + O(x**(-4), (x, oo))
e = exp(exp(x) / (1 - 1/x))
assert e.aseries(x) == exp(exp(x) / (1 - 1/x))
# The implementation of bound in aseries is incorrect currently. This test
# should be commented out when that is fixed.
# assert e.aseries(x, bound=3) == exp(exp(x) / x**2)*exp(exp(x) / x)*exp(-exp(x) + exp(x)/(1 - 1/x) - \
# exp(x) / x - exp(x) / x**2) * exp(exp(x))
e = exp(sin(1/x + exp(-exp(x)))) - exp(sin(1/x))
assert e.aseries(x, n=4) == (-1/(2*x**3) + 1/x + 1 + O(x**(-4), (x, oo)))*exp(-exp(x))
e = exp(exp(x)) * (exp(sin(1/x + 1/exp(exp(x)))) - exp(sin(1/x)))
assert e.aseries(x, n=4) == -1/(2*x**3) + 1/x + 1 + O(x**(-4), (x, oo))
n = Symbol('n', integer=True)
e = (sqrt(n)*log(n)**2*exp(sqrt(log(n))*log(log(n))**2*exp(sqrt(log(log(n)))*log(log(log(n)))**3)))/n
assert e.aseries(n) == \
exp(exp(sqrt(log(log(n)))*log(log(log(n)))**3)*sqrt(log(n))*log(log(n))**2)*log(n)**2/sqrt(n)
def test_hierarchical():
e = sin(1/x + exp(-x))
assert e.aseries(x, n=3, hir=True) == -exp(-2*x)*sin(1/x)/2 + \
exp(-x)*cos(1/x) + sin(1/x) + O(exp(-3*x), (x, oo))
e = sin(x) * cos(exp(-x))
assert e.aseries(x, hir=True) == exp(-4*x)*sin(x)/24 - \
exp(-2*x)*sin(x)/2 + sin(x) + O(exp(-6*x), (x, oo))
raises(PoleError, lambda: e.aseries(x))
|
294fec718d150473e0d570a471357181a67c5dcc236d76f14e1b31b70e4f8003 | from sympy import (residue, Symbol, Function, sin, I, exp, log, pi, S,
factorial, sqrt, Rational, tan, cot, tanh)
from sympy.testing.pytest import XFAIL, raises
from sympy.abc import x, z, a, s
def test_basic1():
assert residue(1/x, x, 0) == 1
assert residue(-2/x, x, 0) == -2
assert residue(81/x, x, 0) == 81
assert residue(1/x**2, x, 0) == 0
assert residue(0, x, 0) == 0
assert residue(5, x, 0) == 0
assert residue(x, x, 0) == 0
assert residue(x**2, x, 0) == 0
def test_basic2():
assert residue(1/x, x, 1) == 0
assert residue(-2/x, x, 1) == 0
assert residue(81/x, x, -1) == 0
assert residue(1/x**2, x, 1) == 0
assert residue(0, x, 1) == 0
assert residue(5, x, 1) == 0
assert residue(x, x, 1) == 0
assert residue(x**2, x, 5) == 0
def test_f():
f = Function("f")
assert residue(f(x)/x**5, x, 0) == f(x).diff(x, 4).subs(x, 0)/24
def test_functions():
assert residue(1/sin(x), x, 0) == 1
assert residue(2/sin(x), x, 0) == 2
assert residue(1/sin(x)**2, x, 0) == 0
assert residue(1/sin(x)**5, x, 0) == Rational(3, 8)
def test_expressions():
assert residue(1/(x + 1), x, 0) == 0
assert residue(1/(x + 1), x, -1) == 1
assert residue(1/(x**2 + 1), x, -1) == 0
assert residue(1/(x**2 + 1), x, I) == -I/2
assert residue(1/(x**2 + 1), x, -I) == I/2
assert residue(1/(x**4 + 1), x, 0) == 0
assert residue(1/(x**4 + 1), x, exp(I*pi/4)).equals(-(Rational(1, 4) + I/4)/sqrt(2))
assert residue(1/(x**2 + a**2)**2, x, a*I) == -I/4/a**3
@XFAIL
def test_expressions_failing():
n = Symbol('n', integer=True, positive=True)
assert residue(exp(z)/(z - pi*I/4*a)**n, z, I*pi*a) == \
exp(I*pi*a/4)/factorial(n - 1)
def test_NotImplemented():
raises(NotImplementedError, lambda: residue(exp(1/z), z, 0))
def test_bug():
assert residue(2**(z)*(s + z)*(1 - s - z)/z**2, z, 0) == \
1 + s*log(2) - s**2*log(2) - 2*s
def test_issue_5654():
assert residue(1/(x**2 + a**2)**2, x, a*I) == -I/(4*a**3)
def test_issue_6499():
assert residue(1/(exp(z) - 1), z, 0) == 1
def test_issue_14037():
assert residue(sin(x**50)/x**51, x, 0) == 1
def test_issue_21176():
f = x**2*cot(pi*x)/(x**4 + 1)
assert residue(f, x, -sqrt(2)/2 - sqrt(2)*I/2).cancel().together(deep=True)\
== sqrt(2)*(1 - I)/(8*tan(sqrt(2)*pi*(1 + I)/2))
def test_issue_21177():
r = -sqrt(3)*tanh(sqrt(3)*pi/2)/3
a = residue(cot(pi*x)/((x - 1)*(x - 2) + 1), x, S(3)/2 - sqrt(3)*I/2)
b = residue(cot(pi*x)/(x**2 - 3*x + 3), x, S(3)/2 - sqrt(3)*I/2)
assert a == r
assert (b - a).cancel() == 0
|
ea84b5bada5e9bacb3b978b47cad149dc8f10bed325e9ba3cb5efba0ea164a6f | from sympy import (Symbol, Rational, ln, exp, log, sqrt, E, O, pi, I, sinh,
sin, cosh, cos, tanh, coth, asinh, acosh, atanh, acoth, tan, cot, Integer,
PoleError, floor, ceiling, asin, symbols, limit, sign, cbrt,
Derivative, S)
from sympy.abc import x, y, z
from sympy.testing.pytest import raises, XFAIL
def test_simple_1():
assert x.nseries(x, n=5) == x
assert y.nseries(x, n=5) == y
assert (1/(x*y)).nseries(y, n=5) == 1/(x*y)
assert Rational(3, 4).nseries(x, n=5) == Rational(3, 4)
assert x.nseries() == x
def test_mul_0():
assert (x*ln(x)).nseries(x, n=5) == x*ln(x)
def test_mul_1():
assert (x*ln(2 + x)).nseries(x, n=5) == x*log(2) + x**2/2 - x**3/8 + \
x**4/24 + O(x**5)
assert (x*ln(1 + x)).nseries(
x, n=5) == x**2 - x**3/2 + x**4/3 + O(x**5)
def test_pow_0():
assert (x**2).nseries(x, n=5) == x**2
assert (1/x).nseries(x, n=5) == 1/x
assert (1/x**2).nseries(x, n=5) == 1/x**2
assert (x**Rational(2, 3)).nseries(x, n=5) == (x**Rational(2, 3))
assert (sqrt(x)**3).nseries(x, n=5) == (sqrt(x)**3)
def test_pow_1():
assert ((1 + x)**2).nseries(x, n=5) == x**2 + 2*x + 1
# https://github.com/sympy/sympy/issues/21075
assert ((sqrt(x) + 1)**2).nseries(x) == 2*sqrt(x) + x + 1
assert ((sqrt(x) + cbrt(x))**2).nseries(x) == 2*x**Rational(5, 6)\
+ x**Rational(2, 3) + x
def test_geometric_1():
assert (1/(1 - x)).nseries(x, n=5) == 1 + x + x**2 + x**3 + x**4 + O(x**5)
assert (x/(1 - x)).nseries(x, n=6) == x + x**2 + x**3 + x**4 + x**5 + O(x**6)
assert (x**3/(1 - x)).nseries(x, n=8) == x**3 + x**4 + x**5 + x**6 + \
x**7 + O(x**8)
def test_sqrt_1():
assert sqrt(1 + x).nseries(x, n=5) == 1 + x/2 - x**2/8 + x**3/16 - 5*x**4/128 + O(x**5)
def test_exp_1():
assert exp(x).nseries(x, n=5) == 1 + x + x**2/2 + x**3/6 + x**4/24 + O(x**5)
assert exp(x).nseries(x, n=12) == 1 + x + x**2/2 + x**3/6 + x**4/24 + x**5/120 + \
x**6/720 + x**7/5040 + x**8/40320 + x**9/362880 + x**10/3628800 + \
x**11/39916800 + O(x**12)
assert exp(1/x).nseries(x, n=5) == exp(1/x)
assert exp(1/(1 + x)).nseries(x, n=4) == \
(E*(1 - x - 13*x**3/6 + 3*x**2/2)).expand() + O(x**4)
assert exp(2 + x).nseries(x, n=5) == \
(exp(2)*(1 + x + x**2/2 + x**3/6 + x**4/24)).expand() + O(x**5)
def test_exp_sqrt_1():
assert exp(1 + sqrt(x)).nseries(x, n=3) == \
(exp(1)*(1 + sqrt(x) + x/2 + sqrt(x)*x/6)).expand() + O(sqrt(x)**3)
def test_power_x_x1():
assert (exp(x*ln(x))).nseries(x, n=4) == \
1 + x*log(x) + x**2*log(x)**2/2 + x**3*log(x)**3/6 + O(x**4*log(x)**4)
def test_power_x_x2():
assert (x**x).nseries(x, n=4) == \
1 + x*log(x) + x**2*log(x)**2/2 + x**3*log(x)**3/6 + O(x**4*log(x)**4)
def test_log_singular1():
assert log(1 + 1/x).nseries(x, n=5) == x - log(x) - x**2/2 + x**3/3 - \
x**4/4 + O(x**5)
def test_log_power1():
e = 1 / (1/x + x ** (log(3)/log(2)))
assert e.nseries(x, n=5) == -x**(log(3)/log(2) + 2) + x + O(x**5)
def test_log_series():
l = Symbol('l')
e = 1/(1 - log(x))
assert e.nseries(x, n=5, logx=l) == 1/(1 - l)
def test_log2():
e = log(-1/x)
assert e.nseries(x, n=5) == -log(x) + log(-1)
def test_log3():
l = Symbol('l')
e = 1/log(-1/x)
assert e.nseries(x, n=4, logx=l) == 1/(-l + log(-1))
def test_series1():
e = sin(x)
assert e.nseries(x, 0, 0) != 0
assert e.nseries(x, 0, 0) == O(1, x)
assert e.nseries(x, 0, 1) == O(x, x)
assert e.nseries(x, 0, 2) == x + O(x**2, x)
assert e.nseries(x, 0, 3) == x + O(x**3, x)
assert e.nseries(x, 0, 4) == x - x**3/6 + O(x**4, x)
e = (exp(x) - 1)/x
assert e.nseries(x, 0, 3) == 1 + x/2 + x**2/6 + O(x**3)
assert x.nseries(x, 0, 2) == x
@XFAIL
def test_series1_failing():
assert x.nseries(x, 0, 0) == O(1, x)
assert x.nseries(x, 0, 1) == O(x, x)
def test_seriesbug1():
assert (1/x).nseries(x, 0, 3) == 1/x
assert (x + 1/x).nseries(x, 0, 3) == x + 1/x
def test_series2x():
assert ((x + 1)**(-2)).nseries(x, 0, 4) == 1 - 2*x + 3*x**2 - 4*x**3 + O(x**4, x)
assert ((x + 1)**(-1)).nseries(x, 0, 4) == 1 - x + x**2 - x**3 + O(x**4, x)
assert ((x + 1)**0).nseries(x, 0, 3) == 1
assert ((x + 1)**1).nseries(x, 0, 3) == 1 + x
assert ((x + 1)**2).nseries(x, 0, 3) == x**2 + 2*x + 1
assert ((x + 1)**3).nseries(x, 0, 3) == 1 + 3*x + 3*x**2 + O(x**3)
assert (1/(1 + x)).nseries(x, 0, 4) == 1 - x + x**2 - x**3 + O(x**4, x)
assert (x + 3/(1 + 2*x)).nseries(x, 0, 4) == 3 - 5*x + 12*x**2 - 24*x**3 + O(x**4, x)
assert ((1/x + 1)**3).nseries(x, 0, 3) == 1 + 3/x + 3/x**2 + x**(-3)
assert (1/(1 + 1/x)).nseries(x, 0, 4) == x - x**2 + x**3 - O(x**4, x)
assert (1/(1 + 1/x**2)).nseries(x, 0, 6) == x**2 - x**4 + O(x**6, x)
def test_bug2(): # 1/log(0)*log(0) problem
w = Symbol("w")
e = (w**(-1) + w**(
-log(3)*log(2)**(-1)))**(-1)*(3*w**(-log(3)*log(2)**(-1)) + 2*w**(-1))
e = e.expand()
assert e.nseries(w, 0, 4).subs(w, 0) == 3
def test_exp():
e = (1 + x)**(1/x)
assert e.nseries(x, n=3) == exp(1) - x*exp(1)/2 + 11*exp(1)*x**2/24 + O(x**3)
def test_exp2():
w = Symbol("w")
e = w**(1 - log(x)/(log(2) + log(x)))
logw = Symbol("logw")
assert e.nseries(
w, 0, 1, logx=logw) == exp(logw*log(2)/(log(x) + log(2)))
def test_bug3():
e = (2/x + 3/x**2)/(1/x + 1/x**2)
assert e.nseries(x, n=3) == 3 - x + x**2 + O(x**3)
def test_generalexponent():
p = 2
e = (2/x + 3/x**p)/(1/x + 1/x**p)
assert e.nseries(x, 0, 3) == 3 - x + x**2 + O(x**3)
p = S.Half
e = (2/x + 3/x**p)/(1/x + 1/x**p)
assert e.nseries(x, 0, 2) == 2 - x + sqrt(x) + x**(S(3)/2) + O(x**2)
e = 1 + sqrt(x)
assert e.nseries(x, 0, 4) == 1 + sqrt(x)
# more complicated example
def test_genexp_x():
e = 1/(1 + sqrt(x))
assert e.nseries(x, 0, 2) == \
1 + x - sqrt(x) - sqrt(x)**3 + O(x**2, x)
# more complicated example
def test_genexp_x2():
p = Rational(3, 2)
e = (2/x + 3/x**p)/(1/x + 1/x**p)
assert e.nseries(x, 0, 3) == 3 + x + x**2 - sqrt(x) - x**(S(3)/2) - x**(S(5)/2) + O(x**3)
def test_seriesbug2():
w = Symbol("w")
#simple case (1):
e = ((2*w)/w)**(1 + w)
assert e.nseries(w, 0, 1) == 2 + O(w, w)
assert e.nseries(w, 0, 1).subs(w, 0) == 2
def test_seriesbug2b():
w = Symbol("w")
#test sin
e = sin(2*w)/w
assert e.nseries(w, 0, 3) == 2 - 4*w**2/3 + O(w**3)
def test_seriesbug2d():
w = Symbol("w", real=True)
e = log(sin(2*w)/w)
assert e.series(w, n=5) == log(2) - 2*w**2/3 - 4*w**4/45 + O(w**5)
def test_seriesbug2c():
w = Symbol("w", real=True)
#more complicated case, but sin(x)~x, so the result is the same as in (1)
e = (sin(2*w)/w)**(1 + w)
assert e.series(w, 0, 1) == 2 + O(w)
assert e.series(w, 0, 3) == 2 + 2*w*log(2) + \
w**2*(Rational(-4, 3) + log(2)**2) + O(w**3)
assert e.series(w, 0, 2).subs(w, 0) == 2
def test_expbug4():
x = Symbol("x", real=True)
assert (log(
sin(2*x)/x)*(1 + x)).series(x, 0, 2) == log(2) + x*log(2) + O(x**2, x)
assert exp(
log(sin(2*x)/x)*(1 + x)).series(x, 0, 2) == 2 + 2*x*log(2) + O(x**2)
assert exp(log(2) + O(x)).nseries(x, 0, 2) == 2 + O(x)
assert ((2 + O(x))**(1 + x)).nseries(x, 0, 2) == 2 + O(x)
def test_logbug4():
assert log(2 + O(x)).nseries(x, 0, 2) == log(2) + O(x, x)
def test_expbug5():
assert exp(log(1 + x)/x).nseries(x, n=3) == exp(1) + -exp(1)*x/2 + 11*exp(1)*x**2/24 + O(x**3)
assert exp(O(x)).nseries(x, 0, 2) == 1 + O(x)
def test_sinsinbug():
assert sin(sin(x)).nseries(x, 0, 8) == x - x**3/3 + x**5/10 - 8*x**7/315 + O(x**8)
def test_issue_3258():
a = x/(exp(x) - 1)
assert a.nseries(x, 0, 5) == 1 - x/2 - x**4/720 + x**2/12 + O(x**5)
def test_issue_3204():
x = Symbol("x", nonnegative=True)
f = sin(x**3)**Rational(1, 3)
assert f.nseries(x, 0, 17) == x - x**7/18 - x**13/3240 + O(x**17)
def test_issue_3224():
f = sqrt(1 - sqrt(y))
assert f.nseries(y, 0, 2) == 1 - sqrt(y)/2 - y/8 - sqrt(y)**3/16 + O(y**2)
def test_issue_3463():
from sympy import symbols
w, i = symbols('w,i')
r = log(5)/log(3)
p = w**(-1 + r)
e = 1/x*(-log(w**(1 + r)) + log(w + w**r))
e_ser = -r*log(w)/x + p/x - p**2/(2*x) + O(w)
assert e.nseries(w, n=1) == e_ser
def test_sin():
assert sin(8*x).nseries(x, n=4) == 8*x - 256*x**3/3 + O(x**4)
assert sin(x + y).nseries(x, n=1) == sin(y) + O(x)
assert sin(x + y).nseries(x, n=2) == sin(y) + cos(y)*x + O(x**2)
assert sin(x + y).nseries(x, n=5) == sin(y) + cos(y)*x - sin(y)*x**2/2 - \
cos(y)*x**3/6 + sin(y)*x**4/24 + O(x**5)
def test_issue_3515():
e = sin(8*x)/x
assert e.nseries(x, n=6) == 8 - 256*x**2/3 + 4096*x**4/15 + O(x**6)
def test_issue_3505():
e = sin(x)**(-4)*(sqrt(cos(x))*sin(x)**2 -
cos(x)**Rational(1, 3)*sin(x)**2)
assert e.nseries(x, n=9) == Rational(-1, 12) - 7*x**2/288 - \
43*x**4/10368 - 1123*x**6/2488320 + 377*x**8/29859840 + O(x**9)
def test_issue_3501():
a = Symbol("a")
e = x**(-2)*(x*sin(a + x) - x*sin(a))
assert e.nseries(x, n=6) == cos(a) - sin(a)*x/2 - cos(a)*x**2/6 + \
x**3*sin(a)/24 + x**4*cos(a)/120 - x**5*sin(a)/720 + O(x**6)
e = x**(-2)*(x*cos(a + x) - x*cos(a))
assert e.nseries(x, n=6) == -sin(a) - cos(a)*x/2 + sin(a)*x**2/6 + \
cos(a)*x**3/24 - x**4*sin(a)/120 - x**5*cos(a)/720 + O(x**6)
def test_issue_3502():
e = sin(5*x)/sin(2*x)
assert e.nseries(x, n=2) == Rational(5, 2) + O(x**2)
assert e.nseries(x, n=6) == \
Rational(5, 2) - 35*x**2/4 + 329*x**4/48 + O(x**6)
def test_issue_3503():
e = sin(2 + x)/(2 + x)
assert e.nseries(x, n=2) == sin(2)/2 + x*cos(2)/2 - x*sin(2)/4 + O(x**2)
def test_issue_3506():
e = (x + sin(3*x))**(-2)*(x*(x + sin(3*x)) - (x + sin(3*x))*sin(2*x))
assert e.nseries(x, n=7) == \
Rational(-1, 4) + 5*x**2/96 + 91*x**4/768 + 11117*x**6/129024 + O(x**7)
def test_issue_3508():
x = Symbol("x", real=True)
assert log(sin(x)).series(x, n=5) == log(x) - x**2/6 - x**4/180 + O(x**5)
e = -log(x) + x*(-log(x) + log(sin(2*x))) + log(sin(2*x))
assert e.series(x, n=5) == \
log(2) + log(2)*x - 2*x**2/3 - 2*x**3/3 - 4*x**4/45 + O(x**5)
def test_issue_3507():
e = x**(-4)*(x**2 - x**2*sqrt(cos(x)))
assert e.nseries(x, n=9) == \
Rational(1, 4) + x**2/96 + 19*x**4/5760 + 559*x**6/645120 + 29161*x**8/116121600 + O(x**9)
def test_issue_3639():
assert sin(cos(x)).nseries(x, n=5) == \
sin(1) - x**2*cos(1)/2 - x**4*sin(1)/8 + x**4*cos(1)/24 + O(x**5)
def test_hyperbolic():
assert sinh(x).nseries(x, n=6) == x + x**3/6 + x**5/120 + O(x**6)
assert cosh(x).nseries(x, n=5) == 1 + x**2/2 + x**4/24 + O(x**5)
assert tanh(x).nseries(x, n=6) == x - x**3/3 + 2*x**5/15 + O(x**6)
assert coth(x).nseries(x, n=6) == \
1/x - x**3/45 + x/3 + 2*x**5/945 + O(x**6)
assert asinh(x).nseries(x, n=6) == x - x**3/6 + 3*x**5/40 + O(x**6)
assert acosh(x).nseries(x, n=6) == \
pi*I/2 - I*x - 3*I*x**5/40 - I*x**3/6 + O(x**6)
assert atanh(x).nseries(x, n=6) == x + x**3/3 + x**5/5 + O(x**6)
assert acoth(x).nseries(x, n=6) == x + x**3/3 + x**5/5 + pi*I/2 + O(x**6)
def test_series2():
w = Symbol("w", real=True)
x = Symbol("x", real=True)
e = w**(-2)*(w*exp(1/x - w) - w*exp(1/x))
assert e.nseries(w, n=4) == -exp(1/x) + w*exp(1/x)/2 - w**2*exp(1/x)/6 + w**3*exp(1/x)/24 + O(w**4)
def test_series3():
w = Symbol("w", real=True)
e = w**(-6)*(w**3*tan(w) - w**3*sin(w))
assert e.nseries(w, n=8) == Integer(1)/2 + w**2/8 + 13*w**4/240 + 529*w**6/24192 + O(w**8)
def test_bug4():
w = Symbol("w")
e = x/(w**4 + x**2*w**4 + 2*x*w**4)*w**4
assert e.nseries(w, n=2).removeO().expand() in [x/(1 + 2*x + x**2),
1/(1 + x/2 + 1/x/2)/2, 1/x/(1 + 2/x + x**(-2))]
def test_bug5():
w = Symbol("w")
l = Symbol('l')
e = (-log(w) + log(1 + w*log(x)))**(-2)*w**(-2)*((-log(w) +
log(1 + x*w))*(-log(w) + log(1 + w*log(x)))*w - x*(-log(w) +
log(1 + w*log(x)))*w)
assert e.nseries(w, n=0, logx=l) == x/w/l + 1/w + O(1, w)
assert e.nseries(w, n=1, logx=l) == x/w/l + 1/w - x/l + 1/l*log(x) \
+ x*log(x)/l**2 + O(w)
def test_issue_4115():
assert (sin(x)/(1 - cos(x))).nseries(x, n=1) == 2/x + O(x)
assert (sin(x)**2/(1 - cos(x))).nseries(x, n=1) == 2 + O(x)
def test_pole():
raises(PoleError, lambda: sin(1/x).series(x, 0, 5))
raises(PoleError, lambda: sin(1 + 1/x).series(x, 0, 5))
raises(PoleError, lambda: (x*sin(1/x)).series(x, 0, 5))
def test_expsinbug():
assert exp(sin(x)).series(x, 0, 0) == O(1, x)
assert exp(sin(x)).series(x, 0, 1) == 1 + O(x)
assert exp(sin(x)).series(x, 0, 2) == 1 + x + O(x**2)
assert exp(sin(x)).series(x, 0, 3) == 1 + x + x**2/2 + O(x**3)
assert exp(sin(x)).series(x, 0, 4) == 1 + x + x**2/2 + O(x**4)
assert exp(sin(x)).series(x, 0, 5) == 1 + x + x**2/2 - x**4/8 + O(x**5)
def test_floor():
x = Symbol('x')
assert floor(x).series(x) == 0
assert floor(-x).series(x) == -1
assert floor(sin(x)).series(x) == 0
assert floor(sin(-x)).series(x) == -1
assert floor(x**3).series(x) == 0
assert floor(-x**3).series(x) == -1
assert floor(cos(x)).series(x) == 0
assert floor(cos(-x)).series(x) == 0
assert floor(5 + sin(x)).series(x) == 5
assert floor(5 + sin(-x)).series(x) == 4
assert floor(x).series(x, 2) == 2
assert floor(-x).series(x, 2) == -3
x = Symbol('x', negative=True)
assert floor(x + 1.5).series(x) == 1
def test_ceiling():
assert ceiling(x).series(x) == 1
assert ceiling(-x).series(x) == 0
assert ceiling(sin(x)).series(x) == 1
assert ceiling(sin(-x)).series(x) == 0
assert ceiling(1 - cos(x)).series(x) == 1
assert ceiling(1 - cos(-x)).series(x) == 1
assert ceiling(x).series(x, 2) == 3
assert ceiling(-x).series(x, 2) == -2
def test_abs():
a = Symbol('a')
assert abs(x).nseries(x, n=4) == x
assert abs(-x).nseries(x, n=4) == x
assert abs(x + 1).nseries(x, n=4) == x + 1
assert abs(sin(x)).nseries(x, n=4) == x - Rational(1, 6)*x**3 + O(x**4)
assert abs(sin(-x)).nseries(x, n=4) == x - Rational(1, 6)*x**3 + O(x**4)
assert abs(x - a).nseries(x, 1) == -a*sign(1 - a) + (x - 1)*sign(1 - a) + sign(1 - a)
def test_dir():
assert abs(x).series(x, 0, dir="+") == x
assert abs(x).series(x, 0, dir="-") == -x
assert floor(x + 2).series(x, 0, dir='+') == 2
assert floor(x + 2).series(x, 0, dir='-') == 1
assert floor(x + 2.2).series(x, 0, dir='-') == 2
assert ceiling(x + 2.2).series(x, 0, dir='-') == 3
assert sin(x + y).series(x, 0, dir='-') == sin(x + y).series(x, 0, dir='+')
def test_issue_3504():
a = Symbol("a")
e = asin(a*x)/x
assert e.series(x, 4, n=2).removeO() == \
(x - 4)*(a/(4*sqrt(-16*a**2 + 1)) - asin(4*a)/16) + asin(4*a)/4
def test_issue_4441():
a, b = symbols('a,b')
f = 1/(1 + a*x)
assert f.series(x, 0, 5) == 1 - a*x + a**2*x**2 - a**3*x**3 + \
a**4*x**4 + O(x**5)
f = 1/(1 + (a + b)*x)
assert f.series(x, 0, 3) == 1 + x*(-a - b)\
+ x**2*(a + b)**2 + O(x**3)
def test_issue_4329():
assert tan(x).series(x, pi/2, n=3).removeO() == \
-pi/6 + x/3 - 1/(x - pi/2)
assert cot(x).series(x, pi, n=3).removeO() == \
-x/3 + pi/3 + 1/(x - pi)
assert limit(tan(x)**tan(2*x), x, pi/4) == exp(-1)
def test_issue_5183():
assert abs(x + x**2).series(n=1) == O(x)
assert abs(x + x**2).series(n=2) == x + O(x**2)
assert ((1 + x)**2).series(x, n=6) == x**2 + 2*x + 1
assert (1 + 1/x).series() == 1 + 1/x
assert Derivative(exp(x).series(), x).doit() == \
1 + x + x**2/2 + x**3/6 + x**4/24 + O(x**5)
def test_issue_5654():
a = Symbol('a')
assert (1/(x**2+a**2)**2).nseries(x, x0=I*a, n=0) == \
-I/(4*a**3*(-I*a + x)) - 1/(4*a**2*(-I*a + x)**2) + O(1, (x, I*a))
assert (1/(x**2+a**2)**2).nseries(x, x0=I*a, n=1) == 3/(16*a**4) \
-I/(4*a**3*(-I*a + x)) - 1/(4*a**2*(-I*a + x)**2) + O(-I*a + x, (x, I*a))
def test_issue_5925():
sx = sqrt(x + z).series(z, 0, 1)
sxy = sqrt(x + y + z).series(z, 0, 1)
s1, s2 = sx.subs(x, x + y), sxy
assert (s1 - s2).expand().removeO().simplify() == 0
sx = sqrt(x + z).series(z, 0, 1)
sxy = sqrt(x + y + z).series(z, 0, 1)
assert sxy.subs({x:1, y:2}) == sx.subs(x, 3)
def test_exp_2():
assert exp(x**3).nseries(x, 0, 14) == 1 + x**3 + x**6/2 + x**9/6 + x**12/24 + O(x**14)
|
3507cec30c921d7f6769e5541011537106e61623ad99947d64a89fde650419ba | from functools import reduce
import itertools
from operator import add
from sympy import (
Add, Mul, Pow, Symbol, exp, sqrt, symbols, sympify, cse,
Matrix, S, cos, sin, Eq, Function, Tuple, CRootOf,
IndexedBase, Idx, Piecewise, O, signsimp
)
from sympy.core.function import count_ops
from sympy.simplify.cse_opts import sub_pre, sub_post
from sympy.functions.special.hyper import meijerg
from sympy.simplify import cse_main, cse_opts
from sympy.utilities.iterables import subsets
from sympy.testing.pytest import XFAIL, raises
from sympy.matrices import (MutableDenseMatrix, MutableSparseMatrix,
ImmutableDenseMatrix, ImmutableSparseMatrix)
from sympy.matrices.expressions import MatrixSymbol
w, x, y, z = symbols('w,x,y,z')
x0, x1, x2, x3, x4, x5, x6, x7, x8, x9, x10, x11, x12 = symbols('x:13')
def test_numbered_symbols():
ns = cse_main.numbered_symbols(prefix='y')
assert list(itertools.islice(
ns, 0, 10)) == [Symbol('y%s' % i) for i in range(0, 10)]
ns = cse_main.numbered_symbols(prefix='y')
assert list(itertools.islice(
ns, 10, 20)) == [Symbol('y%s' % i) for i in range(10, 20)]
ns = cse_main.numbered_symbols()
assert list(itertools.islice(
ns, 0, 10)) == [Symbol('x%s' % i) for i in range(0, 10)]
# Dummy "optimization" functions for testing.
def opt1(expr):
return expr + y
def opt2(expr):
return expr*z
def test_preprocess_for_cse():
assert cse_main.preprocess_for_cse(x, [(opt1, None)]) == x + y
assert cse_main.preprocess_for_cse(x, [(None, opt1)]) == x
assert cse_main.preprocess_for_cse(x, [(None, None)]) == x
assert cse_main.preprocess_for_cse(x, [(opt1, opt2)]) == x + y
assert cse_main.preprocess_for_cse(
x, [(opt1, None), (opt2, None)]) == (x + y)*z
def test_postprocess_for_cse():
assert cse_main.postprocess_for_cse(x, [(opt1, None)]) == x
assert cse_main.postprocess_for_cse(x, [(None, opt1)]) == x + y
assert cse_main.postprocess_for_cse(x, [(None, None)]) == x
assert cse_main.postprocess_for_cse(x, [(opt1, opt2)]) == x*z
# Note the reverse order of application.
assert cse_main.postprocess_for_cse(
x, [(None, opt1), (None, opt2)]) == x*z + y
def test_cse_single():
# Simple substitution.
e = Add(Pow(x + y, 2), sqrt(x + y))
substs, reduced = cse([e])
assert substs == [(x0, x + y)]
assert reduced == [sqrt(x0) + x0**2]
subst42, (red42,) = cse([42]) # issue_15082
assert len(subst42) == 0 and red42 == 42
subst_half, (red_half,) = cse([0.5])
assert len(subst_half) == 0 and red_half == 0.5
def test_cse_single2():
# Simple substitution, test for being able to pass the expression directly
e = Add(Pow(x + y, 2), sqrt(x + y))
substs, reduced = cse(e)
assert substs == [(x0, x + y)]
assert reduced == [sqrt(x0) + x0**2]
substs, reduced = cse(Matrix([[1]]))
assert isinstance(reduced[0], Matrix)
subst42, (red42,) = cse(42) # issue 15082
assert len(subst42) == 0 and red42 == 42
subst_half, (red_half,) = cse(0.5) # issue 15082
assert len(subst_half) == 0 and red_half == 0.5
def test_cse_not_possible():
# No substitution possible.
e = Add(x, y)
substs, reduced = cse([e])
assert substs == []
assert reduced == [x + y]
# issue 6329
eq = (meijerg((1, 2), (y, 4), (5,), [], x) +
meijerg((1, 3), (y, 4), (5,), [], x))
assert cse(eq) == ([], [eq])
def test_nested_substitution():
# Substitution within a substitution.
e = Add(Pow(w*x + y, 2), sqrt(w*x + y))
substs, reduced = cse([e])
assert substs == [(x0, w*x + y)]
assert reduced == [sqrt(x0) + x0**2]
def test_subtraction_opt():
# Make sure subtraction is optimized.
e = (x - y)*(z - y) + exp((x - y)*(z - y))
substs, reduced = cse(
[e], optimizations=[(cse_opts.sub_pre, cse_opts.sub_post)])
assert substs == [(x0, (x - y)*(y - z))]
assert reduced == [-x0 + exp(-x0)]
e = -(x - y)*(z - y) + exp(-(x - y)*(z - y))
substs, reduced = cse(
[e], optimizations=[(cse_opts.sub_pre, cse_opts.sub_post)])
assert substs == [(x0, (x - y)*(y - z))]
assert reduced == [x0 + exp(x0)]
# issue 4077
n = -1 + 1/x
e = n/x/(-n)**2 - 1/n/x
assert cse(e, optimizations=[(cse_opts.sub_pre, cse_opts.sub_post)]) == \
([], [0])
def test_multiple_expressions():
e1 = (x + y)*z
e2 = (x + y)*w
substs, reduced = cse([e1, e2])
assert substs == [(x0, x + y)]
assert reduced == [x0*z, x0*w]
l = [w*x*y + z, w*y]
substs, reduced = cse(l)
rsubsts, _ = cse(reversed(l))
assert substs == rsubsts
assert reduced == [z + x*x0, x0]
l = [w*x*y, w*x*y + z, w*y]
substs, reduced = cse(l)
rsubsts, _ = cse(reversed(l))
assert substs == rsubsts
assert reduced == [x1, x1 + z, x0]
l = [(x - z)*(y - z), x - z, y - z]
substs, reduced = cse(l)
rsubsts, _ = cse(reversed(l))
assert substs == [(x0, -z), (x1, x + x0), (x2, x0 + y)]
assert rsubsts == [(x0, -z), (x1, x0 + y), (x2, x + x0)]
assert reduced == [x1*x2, x1, x2]
l = [w*y + w + x + y + z, w*x*y]
assert cse(l) == ([(x0, w*y)], [w + x + x0 + y + z, x*x0])
assert cse([x + y, x + y + z]) == ([(x0, x + y)], [x0, z + x0])
assert cse([x + y, x + z]) == ([], [x + y, x + z])
assert cse([x*y, z + x*y, x*y*z + 3]) == \
([(x0, x*y)], [x0, z + x0, 3 + x0*z])
@XFAIL # CSE of non-commutative Mul terms is disabled
def test_non_commutative_cse():
A, B, C = symbols('A B C', commutative=False)
l = [A*B*C, A*C]
assert cse(l) == ([], l)
l = [A*B*C, A*B]
assert cse(l) == ([(x0, A*B)], [x0*C, x0])
# Test if CSE of non-commutative Mul terms is disabled
def test_bypass_non_commutatives():
A, B, C = symbols('A B C', commutative=False)
l = [A*B*C, A*C]
assert cse(l) == ([], l)
l = [A*B*C, A*B]
assert cse(l) == ([], l)
l = [B*C, A*B*C]
assert cse(l) == ([], l)
@XFAIL # CSE fails when replacing non-commutative sub-expressions
def test_non_commutative_order():
A, B, C = symbols('A B C', commutative=False)
x0 = symbols('x0', commutative=False)
l = [B+C, A*(B+C)]
assert cse(l) == ([(x0, B+C)], [x0, A*x0])
@XFAIL # Worked in gh-11232, but was reverted due to performance considerations
def test_issue_10228():
assert cse([x*y**2 + x*y]) == ([(x0, x*y)], [x0*y + x0])
assert cse([x + y, 2*x + y]) == ([(x0, x + y)], [x0, x + x0])
assert cse((w + 2*x + y + z, w + x + 1)) == (
[(x0, w + x)], [x0 + x + y + z, x0 + 1])
assert cse(((w + x + y + z)*(w - x))/(w + x)) == (
[(x0, w + x)], [(x0 + y + z)*(w - x)/x0])
a, b, c, d, f, g, j, m = symbols('a, b, c, d, f, g, j, m')
exprs = (d*g**2*j*m, 4*a*f*g*m, a*b*c*f**2)
assert cse(exprs) == (
[(x0, g*m), (x1, a*f)], [d*g*j*x0, 4*x0*x1, b*c*f*x1]
)
@XFAIL
def test_powers():
assert cse(x*y**2 + x*y) == ([(x0, x*y)], [x0*y + x0])
def test_issue_4498():
assert cse(w/(x - y) + z/(y - x), optimizations='basic') == \
([], [(w - z)/(x - y)])
def test_issue_4020():
assert cse(x**5 + x**4 + x**3 + x**2, optimizations='basic') \
== ([(x0, x**2)], [x0*(x**3 + x + x0 + 1)])
def test_issue_4203():
assert cse(sin(x**x)/x**x) == ([(x0, x**x)], [sin(x0)/x0])
def test_issue_6263():
e = Eq(x*(-x + 1) + x*(x - 1), 0)
assert cse(e, optimizations='basic') == ([], [True])
def test_dont_cse_tuples():
from sympy import Subs
f = Function("f")
g = Function("g")
name_val, (expr,) = cse(
Subs(f(x, y), (x, y), (0, 1))
+ Subs(g(x, y), (x, y), (0, 1)))
assert name_val == []
assert expr == (Subs(f(x, y), (x, y), (0, 1))
+ Subs(g(x, y), (x, y), (0, 1)))
name_val, (expr,) = cse(
Subs(f(x, y), (x, y), (0, x + y))
+ Subs(g(x, y), (x, y), (0, x + y)))
assert name_val == [(x0, x + y)]
assert expr == Subs(f(x, y), (x, y), (0, x0)) + \
Subs(g(x, y), (x, y), (0, x0))
def test_pow_invpow():
assert cse(1/x**2 + x**2) == \
([(x0, x**2)], [x0 + 1/x0])
assert cse(x**2 + (1 + 1/x**2)/x**2) == \
([(x0, x**2), (x1, 1/x0)], [x0 + x1*(x1 + 1)])
assert cse(1/x**2 + (1 + 1/x**2)*x**2) == \
([(x0, x**2), (x1, 1/x0)], [x0*(x1 + 1) + x1])
assert cse(cos(1/x**2) + sin(1/x**2)) == \
([(x0, x**(-2))], [sin(x0) + cos(x0)])
assert cse(cos(x**2) + sin(x**2)) == \
([(x0, x**2)], [sin(x0) + cos(x0)])
assert cse(y/(2 + x**2) + z/x**2/y) == \
([(x0, x**2)], [y/(x0 + 2) + z/(x0*y)])
assert cse(exp(x**2) + x**2*cos(1/x**2)) == \
([(x0, x**2)], [x0*cos(1/x0) + exp(x0)])
assert cse((1 + 1/x**2)/x**2) == \
([(x0, x**(-2))], [x0*(x0 + 1)])
assert cse(x**(2*y) + x**(-2*y)) == \
([(x0, x**(2*y))], [x0 + 1/x0])
def test_postprocess():
eq = (x + 1 + exp((x + 1)/(y + 1)) + cos(y + 1))
assert cse([eq, Eq(x, z + 1), z - 2, (z + 1)*(x + 1)],
postprocess=cse_main.cse_separate) == \
[[(x0, y + 1), (x2, z + 1), (x, x2), (x1, x + 1)],
[x1 + exp(x1/x0) + cos(x0), z - 2, x1*x2]]
def test_issue_4499():
# previously, this gave 16 constants
from sympy.abc import a, b
B = Function('B')
G = Function('G')
t = Tuple(*
(a, a + S.Half, 2*a, b, 2*a - b + 1, (sqrt(z)/2)**(-2*a + 1)*B(2*a -
b, sqrt(z))*B(b - 1, sqrt(z))*G(b)*G(2*a - b + 1),
sqrt(z)*(sqrt(z)/2)**(-2*a + 1)*B(b, sqrt(z))*B(2*a - b,
sqrt(z))*G(b)*G(2*a - b + 1), sqrt(z)*(sqrt(z)/2)**(-2*a + 1)*B(b - 1,
sqrt(z))*B(2*a - b + 1, sqrt(z))*G(b)*G(2*a - b + 1),
(sqrt(z)/2)**(-2*a + 1)*B(b, sqrt(z))*B(2*a - b + 1,
sqrt(z))*G(b)*G(2*a - b + 1), 1, 0, S.Half, z/2, -b + 1, -2*a + b,
-2*a))
c = cse(t)
ans = (
[(x0, 2*a), (x1, -b), (x2, x0 + x1), (x3, x2 + 1), (x4, sqrt(z)), (x5,
B(b - 1, x4)), (x6, -x0), (x7, (x4/2)**(x6 + 1)*G(b)*G(x3)), (x8,
x7*B(x2, x4)), (x9, B(b, x4)), (x10, x7*B(x3, x4))],
[(a, a + S.Half, x0, b, x3, x5*x8, x4*x8*x9, x10*x4*x5, x10*x9,
1, 0, S.Half, z/2, x1 + 1, b + x6, x6)])
assert ans == c
def test_issue_6169():
r = CRootOf(x**6 - 4*x**5 - 2, 1)
assert cse(r) == ([], [r])
# and a check that the right thing is done with the new
# mechanism
assert sub_post(sub_pre((-x - y)*z - x - y)) == -z*(x + y) - x - y
def test_cse_Indexed():
len_y = 5
y = IndexedBase('y', shape=(len_y,))
x = IndexedBase('x', shape=(len_y,))
i = Idx('i', len_y-1)
expr1 = (y[i+1]-y[i])/(x[i+1]-x[i])
expr2 = 1/(x[i+1]-x[i])
replacements, reduced_exprs = cse([expr1, expr2])
assert len(replacements) > 0
def test_cse_MatrixSymbol():
# MatrixSymbols have non-Basic args, so make sure that works
A = MatrixSymbol("A", 3, 3)
assert cse(A) == ([], [A])
n = symbols('n', integer=True)
B = MatrixSymbol("B", n, n)
assert cse(B) == ([], [B])
def test_cse_MatrixExpr():
from sympy import MatrixSymbol
A = MatrixSymbol('A', 3, 3)
y = MatrixSymbol('y', 3, 1)
expr1 = (A.T*A).I * A * y
expr2 = (A.T*A) * A * y
replacements, reduced_exprs = cse([expr1, expr2])
assert len(replacements) > 0
replacements, reduced_exprs = cse([expr1 + expr2, expr1])
assert replacements
replacements, reduced_exprs = cse([A**2, A + A**2])
assert replacements
def test_Piecewise():
f = Piecewise((-z + x*y, Eq(y, 0)), (-z - x*y, True))
ans = cse(f)
actual_ans = ([(x0, -z), (x1, x*y)],
[Piecewise((x0 + x1, Eq(y, 0)), (x0 - x1, True))])
assert ans == actual_ans
def test_ignore_order_terms():
eq = exp(x).series(x,0,3) + sin(y+x**3) - 1
assert cse(eq) == ([], [sin(x**3 + y) + x + x**2/2 + O(x**3)])
def test_name_conflict():
z1 = x0 + y
z2 = x2 + x3
l = [cos(z1) + z1, cos(z2) + z2, x0 + x2]
substs, reduced = cse(l)
assert [e.subs(reversed(substs)) for e in reduced] == l
def test_name_conflict_cust_symbols():
z1 = x0 + y
z2 = x2 + x3
l = [cos(z1) + z1, cos(z2) + z2, x0 + x2]
substs, reduced = cse(l, symbols("x:10"))
assert [e.subs(reversed(substs)) for e in reduced] == l
def test_symbols_exhausted_error():
l = cos(x+y)+x+y+cos(w+y)+sin(w+y)
sym = [x, y, z]
with raises(ValueError):
cse(l, symbols=sym)
def test_issue_7840():
# daveknippers' example
C393 = sympify( \
'Piecewise((C391 - 1.65, C390 < 0.5), (Piecewise((C391 - 1.65, \
C391 > 2.35), (C392, True)), True))'
)
C391 = sympify( \
'Piecewise((2.05*C390**(-1.03), C390 < 0.5), (2.5*C390**(-0.625), True))'
)
C393 = C393.subs('C391',C391)
# simple substitution
sub = {}
sub['C390'] = 0.703451854
sub['C392'] = 1.01417794
ss_answer = C393.subs(sub)
# cse
substitutions,new_eqn = cse(C393)
for pair in substitutions:
sub[pair[0].name] = pair[1].subs(sub)
cse_answer = new_eqn[0].subs(sub)
# both methods should be the same
assert ss_answer == cse_answer
# GitRay's example
expr = sympify(
"Piecewise((Symbol('ON'), Equality(Symbol('mode'), Symbol('ON'))), \
(Piecewise((Piecewise((Symbol('OFF'), StrictLessThan(Symbol('x'), \
Symbol('threshold'))), (Symbol('ON'), true)), Equality(Symbol('mode'), \
Symbol('AUTO'))), (Symbol('OFF'), true)), true))"
)
substitutions, new_eqn = cse(expr)
# this Piecewise should be exactly the same
assert new_eqn[0] == expr
# there should not be any replacements
assert len(substitutions) < 1
def test_issue_8891():
for cls in (MutableDenseMatrix, MutableSparseMatrix,
ImmutableDenseMatrix, ImmutableSparseMatrix):
m = cls(2, 2, [x + y, 0, 0, 0])
res = cse([x + y, m])
ans = ([(x0, x + y)], [x0, cls([[x0, 0], [0, 0]])])
assert res == ans
assert isinstance(res[1][-1], cls)
def test_issue_11230():
# a specific test that always failed
a, b, f, k, l, i = symbols('a b f k l i')
p = [a*b*f*k*l, a*i*k**2*l, f*i*k**2*l]
R, C = cse(p)
assert not any(i.is_Mul for a in C for i in a.args)
# random tests for the issue
from random import choice
from sympy.core.function import expand_mul
s = symbols('a:m')
# 35 Mul tests, none of which should ever fail
ex = [Mul(*[choice(s) for i in range(5)]) for i in range(7)]
for p in subsets(ex, 3):
p = list(p)
R, C = cse(p)
assert not any(i.is_Mul for a in C for i in a.args)
for ri in reversed(R):
for i in range(len(C)):
C[i] = C[i].subs(*ri)
assert p == C
# 35 Add tests, none of which should ever fail
ex = [Add(*[choice(s[:7]) for i in range(5)]) for i in range(7)]
for p in subsets(ex, 3):
p = list(p)
R, C = cse(p)
assert not any(i.is_Add for a in C for i in a.args)
for ri in reversed(R):
for i in range(len(C)):
C[i] = C[i].subs(*ri)
# use expand_mul to handle cases like this:
# p = [a + 2*b + 2*e, 2*b + c + 2*e, b + 2*c + 2*g]
# x0 = 2*(b + e) is identified giving a rebuilt p that
# is now `[a + 2*(b + e), c + 2*(b + e), b + 2*c + 2*g]`
assert p == [expand_mul(i) for i in C]
@XFAIL
def test_issue_11577():
def check(eq):
r, c = cse(eq)
assert eq.count_ops() >= \
len(r) + sum([i[1].count_ops() for i in r]) + \
count_ops(c)
eq = x**5*y**2 + x**5*y + x**5
assert cse(eq) == (
[(x0, x**4), (x1, x*y)], [x**5 + x0*x1*y + x0*x1])
# ([(x0, x**5*y)], [x0*y + x0 + x**5]) or
# ([(x0, x**5)], [x0*y**2 + x0*y + x0])
check(eq)
eq = x**2/(y + 1)**2 + x/(y + 1)
assert cse(eq) == (
[(x0, y + 1)], [x**2/x0**2 + x/x0])
# ([(x0, x/(y + 1))], [x0**2 + x0])
check(eq)
def test_hollow_rejection():
eq = [x + 3, x + 4]
assert cse(eq) == ([], eq)
def test_cse_ignore():
exprs = [exp(y)*(3*y + 3*sqrt(x+1)), exp(y)*(5*y + 5*sqrt(x+1))]
subst1, red1 = cse(exprs)
assert any(y in sub.free_symbols for _, sub in subst1), "cse failed to identify any term with y"
subst2, red2 = cse(exprs, ignore=(y,)) # y is not allowed in substitutions
assert not any(y in sub.free_symbols for _, sub in subst2), "Sub-expressions containing y must be ignored"
assert any(sub - sqrt(x + 1) == 0 for _, sub in subst2), "cse failed to identify sqrt(x + 1) as sub-expression"
def test_cse_ignore_issue_15002():
l = [
w*exp(x)*exp(-z),
exp(y)*exp(x)*exp(-z)
]
substs, reduced = cse(l, ignore=(x,))
rl = [e.subs(reversed(substs)) for e in reduced]
assert rl == l
def test_cse__performance():
nexprs, nterms = 3, 20
x = symbols('x:%d' % nterms)
exprs = [
reduce(add, [x[j]*(-1)**(i+j) for j in range(nterms)])
for i in range(nexprs)
]
assert (exprs[0] + exprs[1]).simplify() == 0
subst, red = cse(exprs)
assert len(subst) > 0, "exprs[0] == -exprs[2], i.e. a CSE"
for i, e in enumerate(red):
assert (e.subs(reversed(subst)) - exprs[i]).simplify() == 0
def test_issue_12070():
exprs = [x + y, 2 + x + y, x + y + z, 3 + x + y + z]
subst, red = cse(exprs)
assert 6 >= (len(subst) + sum([v.count_ops() for k, v in subst]) +
count_ops(red))
def test_issue_13000():
eq = x/(-4*x**2 + y**2)
cse_eq = cse(eq)[1][0]
assert cse_eq == eq
def test_issue_18203():
eq = CRootOf(x**5 + 11*x - 2, 0) + CRootOf(x**5 + 11*x - 2, 1)
assert cse(eq) == ([], [eq])
def test_unevaluated_mul():
eq = Mul(x + y, x + y, evaluate=False)
assert cse(eq) == ([(x0, x + y)], [x0**2])
def test_cse_release_variables():
from sympy.simplify.cse_main import cse_release_variables
_0, _1, _2, _3, _4 = symbols('_:5')
eqs = [(x + y - 1)**2, x,
x + y, (x + y)/(2*x + 1) + (x + y - 1)**2,
(2*x + 1)**(x + y)]
r, e = cse(eqs, postprocess=cse_release_variables)
# this can change in keeping with the intention of the function
assert r, e == ([
(x0, x + y), (x1, (x0 - 1)**2), (x2, 2*x + 1),
(_3, x0/x2 + x1), (_4, x2**x0), (x2, None), (_0, x1),
(x1, None), (_2, x0), (x0, None), (_1, x)], (_0, _1, _2, _3, _4))
r.reverse()
assert eqs == [i.subs(r) for i in e]
def test_cse_list():
_cse = lambda x: cse(x, list=False)
assert _cse(x) == ([], x)
assert _cse('x') == ([], 'x')
it = [x]
for c in (list, tuple, set, Tuple):
assert _cse(c(it)) == ([], c(it))
d = {x: 1}
assert _cse(d) == ([], d)
def test_issue_18991():
A = MatrixSymbol('A', 2, 2)
assert signsimp(-A * A - A) == -A * A - A
def test_unevaluated_Mul():
m = [Mul(1, 2, evaluate=False)]
assert cse(m) == ([], m)
|
b7328d0478b15d94e2988f7dab381971f849eb929e8ef0d5b5ce96d1fdf75bd8 | from sympy import symbols, re, im, sign, I, Abs, Symbol, \
cos, sin, sqrt, conjugate, log, acos, E, pi, \
Matrix, diff, integrate, trigsimp, S, Rational
from sympy.algebras.quaternion import Quaternion
from sympy.testing.pytest import raises
w, x, y, z = symbols('w:z')
phi = symbols('phi')
def test_quaternion_construction():
q = Quaternion(w, x, y, z)
assert q + q == Quaternion(2*w, 2*x, 2*y, 2*z)
q2 = Quaternion.from_axis_angle((sqrt(3)/3, sqrt(3)/3, sqrt(3)/3),
pi*Rational(2, 3))
assert q2 == Quaternion(S.Half, S.Half,
S.Half, S.Half)
M = Matrix([[cos(phi), -sin(phi), 0], [sin(phi), cos(phi), 0], [0, 0, 1]])
q3 = trigsimp(Quaternion.from_rotation_matrix(M))
assert q3 == Quaternion(sqrt(2)*sqrt(cos(phi) + 1)/2, 0, 0, sqrt(2 - 2*cos(phi))*sign(sin(phi))/2)
nc = Symbol('nc', commutative=False)
raises(ValueError, lambda: Quaternion(w, x, nc, z))
def test_quaternion_complex_real_addition():
a = symbols("a", complex=True)
b = symbols("b", real=True)
# This symbol is not complex:
c = symbols("c", commutative=False)
q = Quaternion(w, x, y, z)
assert a + q == Quaternion(w + re(a), x + im(a), y, z)
assert 1 + q == Quaternion(1 + w, x, y, z)
assert I + q == Quaternion(w, 1 + x, y, z)
assert b + q == Quaternion(w + b, x, y, z)
raises(ValueError, lambda: c + q)
raises(ValueError, lambda: q * c)
raises(ValueError, lambda: c * q)
assert -q == Quaternion(-w, -x, -y, -z)
q1 = Quaternion(3 + 4*I, 2 + 5*I, 0, 7 + 8*I, real_field = False)
q2 = Quaternion(1, 4, 7, 8)
assert q1 + (2 + 3*I) == Quaternion(5 + 7*I, 2 + 5*I, 0, 7 + 8*I)
assert q2 + (2 + 3*I) == Quaternion(3, 7, 7, 8)
assert q1 * (2 + 3*I) == \
Quaternion((2 + 3*I)*(3 + 4*I), (2 + 3*I)*(2 + 5*I), 0, (2 + 3*I)*(7 + 8*I))
assert q2 * (2 + 3*I) == Quaternion(-10, 11, 38, -5)
q1 = Quaternion(1, 2, 3, 4)
q0 = Quaternion(0, 0, 0, 0)
assert q1 + q0 == q1
assert q1 - q0 == q1
assert q1 - q1 == q0
def test_quaternion_evalf():
assert Quaternion(sqrt(2), 0, 0, sqrt(3)).evalf() == Quaternion(sqrt(2).evalf(), 0, 0, sqrt(3).evalf())
assert Quaternion(1/sqrt(2), 0, 0, 1/sqrt(2)).evalf() == Quaternion((1/sqrt(2)).evalf(), 0, 0, (1/sqrt(2)).evalf())
def test_quaternion_functions():
q = Quaternion(w, x, y, z)
q1 = Quaternion(1, 2, 3, 4)
q0 = Quaternion(0, 0, 0, 0)
assert conjugate(q) == Quaternion(w, -x, -y, -z)
assert q.norm() == sqrt(w**2 + x**2 + y**2 + z**2)
assert q.normalize() == Quaternion(w, x, y, z) / sqrt(w**2 + x**2 + y**2 + z**2)
assert q.inverse() == Quaternion(w, -x, -y, -z) / (w**2 + x**2 + y**2 + z**2)
assert q.inverse() == q.pow(-1)
raises(ValueError, lambda: q0.inverse())
assert q.pow(2) == Quaternion(w**2 - x**2 - y**2 - z**2, 2*w*x, 2*w*y, 2*w*z)
assert q**(2) == Quaternion(w**2 - x**2 - y**2 - z**2, 2*w*x, 2*w*y, 2*w*z)
assert q1.pow(-2) == Quaternion(Rational(-7, 225), Rational(-1, 225), Rational(-1, 150), Rational(-2, 225))
assert q1**(-2) == Quaternion(Rational(-7, 225), Rational(-1, 225), Rational(-1, 150), Rational(-2, 225))
assert q1.pow(-0.5) == NotImplemented
raises(TypeError, lambda: q1**(-0.5))
assert q1.exp() == \
Quaternion(E * cos(sqrt(29)),
2 * sqrt(29) * E * sin(sqrt(29)) / 29,
3 * sqrt(29) * E * sin(sqrt(29)) / 29,
4 * sqrt(29) * E * sin(sqrt(29)) / 29)
assert q1._ln() == \
Quaternion(log(sqrt(30)),
2 * sqrt(29) * acos(sqrt(30)/30) / 29,
3 * sqrt(29) * acos(sqrt(30)/30) / 29,
4 * sqrt(29) * acos(sqrt(30)/30) / 29)
assert q1.pow_cos_sin(2) == \
Quaternion(30 * cos(2 * acos(sqrt(30)/30)),
60 * sqrt(29) * sin(2 * acos(sqrt(30)/30)) / 29,
90 * sqrt(29) * sin(2 * acos(sqrt(30)/30)) / 29,
120 * sqrt(29) * sin(2 * acos(sqrt(30)/30)) / 29)
assert diff(Quaternion(x, x, x, x), x) == Quaternion(1, 1, 1, 1)
assert integrate(Quaternion(x, x, x, x), x) == \
Quaternion(x**2 / 2, x**2 / 2, x**2 / 2, x**2 / 2)
assert Quaternion.rotate_point((1, 1, 1), q1) == (S.One / 5, 1, S(7) / 5)
n = Symbol('n')
raises(TypeError, lambda: q1**n)
n = Symbol('n', integer=True)
raises(TypeError, lambda: q1**n)
def test_quaternion_conversions():
q1 = Quaternion(1, 2, 3, 4)
assert q1.to_axis_angle() == ((2 * sqrt(29)/29,
3 * sqrt(29)/29,
4 * sqrt(29)/29),
2 * acos(sqrt(30)/30))
assert q1.to_rotation_matrix() == Matrix([[Rational(-2, 3), Rational(2, 15), Rational(11, 15)],
[Rational(2, 3), Rational(-1, 3), Rational(2, 3)],
[Rational(1, 3), Rational(14, 15), Rational(2, 15)]])
assert q1.to_rotation_matrix((1, 1, 1)) == Matrix([[Rational(-2, 3), Rational(2, 15), Rational(11, 15), Rational(4, 5)],
[Rational(2, 3), Rational(-1, 3), Rational(2, 3), S.Zero],
[Rational(1, 3), Rational(14, 15), Rational(2, 15), Rational(-2, 5)],
[S.Zero, S.Zero, S.Zero, S.One]])
theta = symbols("theta", real=True)
q2 = Quaternion(cos(theta/2), 0, 0, sin(theta/2))
assert trigsimp(q2.to_rotation_matrix()) == Matrix([
[cos(theta), -sin(theta), 0],
[sin(theta), cos(theta), 0],
[0, 0, 1]])
assert q2.to_axis_angle() == ((0, 0, sin(theta/2)/Abs(sin(theta/2))),
2*acos(cos(theta/2)))
assert trigsimp(q2.to_rotation_matrix((1, 1, 1))) == Matrix([
[cos(theta), -sin(theta), 0, sin(theta) - cos(theta) + 1],
[sin(theta), cos(theta), 0, -sin(theta) - cos(theta) + 1],
[0, 0, 1, 0],
[0, 0, 0, 1]])
def test_quaternion_rotation_iss1593():
"""
There was a sign mistake in the definition,
of the rotation matrix. This tests that particular sign mistake.
See issue 1593 for reference.
See wikipedia
https://en.wikipedia.org/wiki/Quaternions_and_spatial_rotation#Quaternion-derived_rotation_matrix
for the correct definition
"""
q = Quaternion(cos(phi/2), sin(phi/2), 0, 0)
assert(trigsimp(q.to_rotation_matrix()) == Matrix([
[1, 0, 0],
[0, cos(phi), -sin(phi)],
[0, sin(phi), cos(phi)]]))
def test_quaternion_multiplication():
q1 = Quaternion(3 + 4*I, 2 + 5*I, 0, 7 + 8*I, real_field = False)
q2 = Quaternion(1, 2, 3, 5)
q3 = Quaternion(1, 1, 1, y)
assert Quaternion._generic_mul(4, 1) == 4
assert Quaternion._generic_mul(4, q1) == Quaternion(12 + 16*I, 8 + 20*I, 0, 28 + 32*I)
assert q2.mul(2) == Quaternion(2, 4, 6, 10)
assert q2.mul(q3) == Quaternion(-5*y - 4, 3*y - 2, 9 - 2*y, y + 4)
assert q2.mul(q3) == q2*q3
z = symbols('z', complex=True)
z_quat = Quaternion(re(z), im(z), 0, 0)
q = Quaternion(*symbols('q:4', real=True))
assert z * q == z_quat * q
assert q * z == q * z_quat
def test_issue_16318():
#for rtruediv
q0 = Quaternion(0, 0, 0, 0)
raises(ValueError, lambda: 1/q0)
#for rotate_point
q = Quaternion(1, 2, 3, 4)
(axis, angle) = q.to_axis_angle()
assert Quaternion.rotate_point((1, 1, 1), (axis, angle)) == (S.One / 5, 1, S(7) / 5)
#test for to_axis_angle
q = Quaternion(-1, 1, 1, 1)
axis = (-sqrt(3)/3, -sqrt(3)/3, -sqrt(3)/3)
angle = 2*pi/3
assert (axis, angle) == q.to_axis_angle()
|
04365117512e928900be82fda574506f649a92b8dfdfb9188b0303c761d4c771 | from sympy.core import Lambda, Symbol, symbols
from sympy.diffgeom.rn import R2, R2_p, R2_r, R3_r, R3_c, R3_s, R2_origin
from sympy.diffgeom import (CoordSystem, Commutator, Differential, TensorProduct,
WedgeProduct, BaseCovarDerivativeOp, CovarDerivativeOp, LieDerivative,
covariant_order, contravariant_order, twoform_to_matrix, metric_to_Christoffel_1st,
metric_to_Christoffel_2nd, metric_to_Riemann_components,
metric_to_Ricci_components, intcurve_diffequ, intcurve_series)
from sympy.simplify import trigsimp, simplify
from sympy.functions import sqrt, atan2, sin
from sympy.matrices import Matrix
from sympy.testing.pytest import raises, nocache_fail
from sympy.testing.pytest import warns_deprecated_sympy
TP = TensorProduct
def test_coordsys_transform():
# test inverse transforms
p, q, r, s = symbols('p q r s')
rel = {('first', 'second'): [(p, q), (q, -p)]}
R2_pq = CoordSystem('first', R2_origin, [p, q], rel)
R2_rs = CoordSystem('second', R2_origin, [r, s], rel)
r, s = R2_rs.symbols
assert R2_rs.transform(R2_pq) == Matrix([[-s], [r]])
# inverse transform impossible case
a, b = symbols('a b', positive=True)
rel = {('first', 'second'): [(a,), (-a,)]}
R2_a = CoordSystem('first', R2_origin, [a], rel)
R2_b = CoordSystem('second', R2_origin, [b], rel)
# This transformation is uninvertible because there is no positive a, b satisfying a = -b
with raises(NotImplementedError):
R2_b.transform(R2_a)
# inverse transform ambiguous case
c, d = symbols('c d')
rel = {('first', 'second'): [(c,), (c**2,)]}
R2_c = CoordSystem('first', R2_origin, [c], rel)
R2_d = CoordSystem('second', R2_origin, [d], rel)
# The transform method should throw if it finds multiple inverses for a coordinate transformation.
with raises(ValueError):
R2_d.transform(R2_c)
# test indirect transformation
a, b, c, d, e, f = symbols('a, b, c, d, e, f')
rel = {('C1', 'C2'): [(a, b), (2*a, 3*b)],
('C2', 'C3'): [(c, d), (3*c, 2*d)]}
C1 = CoordSystem('C1', R2_origin, (a, b), rel)
C2 = CoordSystem('C2', R2_origin, (c, d), rel)
C3 = CoordSystem('C3', R2_origin, (e, f), rel)
a, b = C1.symbols
c, d = C2.symbols
e, f = C3.symbols
assert C2.transform(C1) == Matrix([c/2, d/3])
assert C1.transform(C3) == Matrix([6*a, 6*b])
assert C3.transform(C1) == Matrix([e/6, f/6])
assert C3.transform(C2) == Matrix([e/3, f/2])
a, b, c, d, e, f = symbols('a, b, c, d, e, f')
rel = {('C1', 'C2'): [(a, b), (2*a, 3*b + 1)],
('C3', 'C2'): [(e, f), (-e - 2, 2*f)]}
C1 = CoordSystem('C1', R2_origin, (a, b), rel)
C2 = CoordSystem('C2', R2_origin, (c, d), rel)
C3 = CoordSystem('C3', R2_origin, (e, f), rel)
a, b = C1.symbols
c, d = C2.symbols
e, f = C3.symbols
assert C2.transform(C1) == Matrix([c/2, (d - 1)/3])
assert C1.transform(C3) == Matrix([-2*a - 2, (3*b + 1)/2])
assert C3.transform(C1) == Matrix([-e/2 - 1, (2*f - 1)/3])
assert C3.transform(C2) == Matrix([-e - 2, 2*f])
# old signature uses Lambda
a, b, c, d, e, f = symbols('a, b, c, d, e, f')
rel = {('C1', 'C2'): Lambda((a, b), (2*a, 3*b + 1)),
('C3', 'C2'): Lambda((e, f), (-e - 2, 2*f))}
C1 = CoordSystem('C1', R2_origin, (a, b), rel)
C2 = CoordSystem('C2', R2_origin, (c, d), rel)
C3 = CoordSystem('C3', R2_origin, (e, f), rel)
a, b = C1.symbols
c, d = C2.symbols
e, f = C3.symbols
assert C2.transform(C1) == Matrix([c/2, (d - 1)/3])
assert C1.transform(C3) == Matrix([-2*a - 2, (3*b + 1)/2])
assert C3.transform(C1) == Matrix([-e/2 - 1, (2*f - 1)/3])
assert C3.transform(C2) == Matrix([-e - 2, 2*f])
def test_R2():
x0, y0, r0, theta0 = symbols('x0, y0, r0, theta0', real=True)
point_r = R2_r.point([x0, y0])
point_p = R2_p.point([r0, theta0])
# r**2 = x**2 + y**2
assert (R2.r**2 - R2.x**2 - R2.y**2).rcall(point_r) == 0
assert trigsimp( (R2.r**2 - R2.x**2 - R2.y**2).rcall(point_p) ) == 0
assert trigsimp(R2.e_r(R2.x**2 + R2.y**2).rcall(point_p).doit()) == 2*r0
# polar->rect->polar == Id
a, b = symbols('a b', positive=True)
m = Matrix([[a], [b]])
#TODO assert m == R2_r.transform(R2_p, R2_p.transform(R2_r, [a, b])).applyfunc(simplify)
assert m == R2_p.transform(R2_r, R2_r.transform(R2_p, m)).applyfunc(simplify)
# deprecated method
with warns_deprecated_sympy():
assert m == R2_p.coord_tuple_transform_to(
R2_r, R2_r.coord_tuple_transform_to(R2_p, m)).applyfunc(simplify)
def test_R3():
a, b, c = symbols('a b c', positive=True)
m = Matrix([[a], [b], [c]])
assert m == R3_c.transform(R3_r, R3_r.transform(R3_c, m)).applyfunc(simplify)
#TODO assert m == R3_r.transform(R3_c, R3_c.transform(R3_r, m)).applyfunc(simplify)
assert m == R3_s.transform(
R3_r, R3_r.transform(R3_s, m)).applyfunc(simplify)
#TODO assert m == R3_r.transform(R3_s, R3_s.transform(R3_r, m)).applyfunc(simplify)
assert m == R3_s.transform(
R3_c, R3_c.transform(R3_s, m)).applyfunc(simplify)
#TODO assert m == R3_c.transform(R3_s, R3_s.transform(R3_c, m)).applyfunc(simplify)
with warns_deprecated_sympy():
assert m == R3_c.coord_tuple_transform_to(
R3_r, R3_r.coord_tuple_transform_to(R3_c, m)).applyfunc(simplify)
#TODO assert m == R3_r.coord_tuple_transform_to(R3_c, R3_c.coord_tuple_transform_to(R3_r, m)).applyfunc(simplify)
assert m == R3_s.coord_tuple_transform_to(
R3_r, R3_r.coord_tuple_transform_to(R3_s, m)).applyfunc(simplify)
#TODO assert m == R3_r.coord_tuple_transform_to(R3_s, R3_s.coord_tuple_transform_to(R3_r, m)).applyfunc(simplify)
assert m == R3_s.coord_tuple_transform_to(
R3_c, R3_c.coord_tuple_transform_to(R3_s, m)).applyfunc(simplify)
#TODO assert m == R3_c.coord_tuple_transform_to(R3_s, R3_s.coord_tuple_transform_to(R3_c, m)).applyfunc(simplify)
def test_CoordinateSymbol():
x, y = R2_r.symbols
r, theta = R2_p.symbols
assert y.rewrite(R2_p) == r*sin(theta)
def test_point():
x, y = symbols('x, y')
p = R2_r.point([x, y])
assert p.free_symbols == {x, y}
assert p.coords(R2_r) == p.coords() == Matrix([x, y])
assert p.coords(R2_p) == Matrix([sqrt(x**2 + y**2), atan2(y, x)])
def test_commutator():
assert Commutator(R2.e_x, R2.e_y) == 0
assert Commutator(R2.x*R2.e_x, R2.x*R2.e_x) == 0
assert Commutator(R2.x*R2.e_x, R2.x*R2.e_y) == R2.x*R2.e_y
c = Commutator(R2.e_x, R2.e_r)
assert c(R2.x) == R2.y*(R2.x**2 + R2.y**2)**(-1)*sin(R2.theta)
def test_differential():
xdy = R2.x*R2.dy
dxdy = Differential(xdy)
assert xdy.rcall(None) == xdy
assert dxdy(R2.e_x, R2.e_y) == 1
assert dxdy(R2.e_x, R2.x*R2.e_y) == R2.x
assert Differential(dxdy) == 0
def test_products():
assert TensorProduct(
R2.dx, R2.dy)(R2.e_x, R2.e_y) == R2.dx(R2.e_x)*R2.dy(R2.e_y) == 1
assert TensorProduct(R2.dx, R2.dy)(None, R2.e_y) == R2.dx
assert TensorProduct(R2.dx, R2.dy)(R2.e_x, None) == R2.dy
assert TensorProduct(R2.dx, R2.dy)(R2.e_x) == R2.dy
assert TensorProduct(R2.x, R2.dx) == R2.x*R2.dx
assert TensorProduct(
R2.e_x, R2.e_y)(R2.x, R2.y) == R2.e_x(R2.x) * R2.e_y(R2.y) == 1
assert TensorProduct(R2.e_x, R2.e_y)(None, R2.y) == R2.e_x
assert TensorProduct(R2.e_x, R2.e_y)(R2.x, None) == R2.e_y
assert TensorProduct(R2.e_x, R2.e_y)(R2.x) == R2.e_y
assert TensorProduct(R2.x, R2.e_x) == R2.x * R2.e_x
assert TensorProduct(
R2.dx, R2.e_y)(R2.e_x, R2.y) == R2.dx(R2.e_x) * R2.e_y(R2.y) == 1
assert TensorProduct(R2.dx, R2.e_y)(None, R2.y) == R2.dx
assert TensorProduct(R2.dx, R2.e_y)(R2.e_x, None) == R2.e_y
assert TensorProduct(R2.dx, R2.e_y)(R2.e_x) == R2.e_y
assert TensorProduct(R2.x, R2.e_x) == R2.x * R2.e_x
assert TensorProduct(
R2.e_x, R2.dy)(R2.x, R2.e_y) == R2.e_x(R2.x) * R2.dy(R2.e_y) == 1
assert TensorProduct(R2.e_x, R2.dy)(None, R2.e_y) == R2.e_x
assert TensorProduct(R2.e_x, R2.dy)(R2.x, None) == R2.dy
assert TensorProduct(R2.e_x, R2.dy)(R2.x) == R2.dy
assert TensorProduct(R2.e_y,R2.e_x)(R2.x**2 + R2.y**2,R2.x**2 + R2.y**2) == 4*R2.x*R2.y
assert WedgeProduct(R2.dx, R2.dy)(R2.e_x, R2.e_y) == 1
assert WedgeProduct(R2.e_x, R2.e_y)(R2.x, R2.y) == 1
def test_lie_derivative():
assert LieDerivative(R2.e_x, R2.y) == R2.e_x(R2.y) == 0
assert LieDerivative(R2.e_x, R2.x) == R2.e_x(R2.x) == 1
assert LieDerivative(R2.e_x, R2.e_x) == Commutator(R2.e_x, R2.e_x) == 0
assert LieDerivative(R2.e_x, R2.e_r) == Commutator(R2.e_x, R2.e_r)
assert LieDerivative(R2.e_x + R2.e_y, R2.x) == 1
assert LieDerivative(
R2.e_x, TensorProduct(R2.dx, R2.dy))(R2.e_x, R2.e_y) == 0
@nocache_fail
def test_covar_deriv():
ch = metric_to_Christoffel_2nd(TP(R2.dx, R2.dx) + TP(R2.dy, R2.dy))
cvd = BaseCovarDerivativeOp(R2_r, 0, ch)
assert cvd(R2.x) == 1
# This line fails if the cache is disabled:
assert cvd(R2.x*R2.e_x) == R2.e_x
cvd = CovarDerivativeOp(R2.x*R2.e_x, ch)
assert cvd(R2.x) == R2.x
assert cvd(R2.x*R2.e_x) == R2.x*R2.e_x
def test_intcurve_diffequ():
t = symbols('t')
start_point = R2_r.point([1, 0])
vector_field = -R2.y*R2.e_x + R2.x*R2.e_y
equations, init_cond = intcurve_diffequ(vector_field, t, start_point)
assert str(equations) == '[f_1(t) + Derivative(f_0(t), t), -f_0(t) + Derivative(f_1(t), t)]'
assert str(init_cond) == '[f_0(0) - 1, f_1(0)]'
equations, init_cond = intcurve_diffequ(vector_field, t, start_point, R2_p)
assert str(
equations) == '[Derivative(f_0(t), t), Derivative(f_1(t), t) - 1]'
assert str(init_cond) == '[f_0(0) - 1, f_1(0)]'
def test_helpers_and_coordinate_dependent():
one_form = R2.dr + R2.dx
two_form = Differential(R2.x*R2.dr + R2.r*R2.dx)
three_form = Differential(
R2.y*two_form) + Differential(R2.x*Differential(R2.r*R2.dr))
metric = TensorProduct(R2.dx, R2.dx) + TensorProduct(R2.dy, R2.dy)
metric_ambig = TensorProduct(R2.dx, R2.dx) + TensorProduct(R2.dr, R2.dr)
misform_a = TensorProduct(R2.dr, R2.dr) + R2.dr
misform_b = R2.dr**4
misform_c = R2.dx*R2.dy
twoform_not_sym = TensorProduct(R2.dx, R2.dx) + TensorProduct(R2.dx, R2.dy)
twoform_not_TP = WedgeProduct(R2.dx, R2.dy)
one_vector = R2.e_x + R2.e_y
two_vector = TensorProduct(R2.e_x, R2.e_y)
three_vector = TensorProduct(R2.e_x, R2.e_y, R2.e_x)
two_wp = WedgeProduct(R2.e_x,R2.e_y)
assert covariant_order(one_form) == 1
assert covariant_order(two_form) == 2
assert covariant_order(three_form) == 3
assert covariant_order(two_form + metric) == 2
assert covariant_order(two_form + metric_ambig) == 2
assert covariant_order(two_form + twoform_not_sym) == 2
assert covariant_order(two_form + twoform_not_TP) == 2
assert contravariant_order(one_vector) == 1
assert contravariant_order(two_vector) == 2
assert contravariant_order(three_vector) == 3
assert contravariant_order(two_vector + two_wp) == 2
raises(ValueError, lambda: covariant_order(misform_a))
raises(ValueError, lambda: covariant_order(misform_b))
raises(ValueError, lambda: covariant_order(misform_c))
assert twoform_to_matrix(metric) == Matrix([[1, 0], [0, 1]])
assert twoform_to_matrix(twoform_not_sym) == Matrix([[1, 0], [1, 0]])
assert twoform_to_matrix(twoform_not_TP) == Matrix([[0, -1], [1, 0]])
raises(ValueError, lambda: twoform_to_matrix(one_form))
raises(ValueError, lambda: twoform_to_matrix(three_form))
raises(ValueError, lambda: twoform_to_matrix(metric_ambig))
raises(ValueError, lambda: metric_to_Christoffel_1st(twoform_not_sym))
raises(ValueError, lambda: metric_to_Christoffel_2nd(twoform_not_sym))
raises(ValueError, lambda: metric_to_Riemann_components(twoform_not_sym))
raises(ValueError, lambda: metric_to_Ricci_components(twoform_not_sym))
def test_correct_arguments():
raises(ValueError, lambda: R2.e_x(R2.e_x))
raises(ValueError, lambda: R2.e_x(R2.dx))
raises(ValueError, lambda: Commutator(R2.e_x, R2.x))
raises(ValueError, lambda: Commutator(R2.dx, R2.e_x))
raises(ValueError, lambda: Differential(Differential(R2.e_x)))
raises(ValueError, lambda: R2.dx(R2.x))
raises(ValueError, lambda: LieDerivative(R2.dx, R2.dx))
raises(ValueError, lambda: LieDerivative(R2.x, R2.dx))
raises(ValueError, lambda: CovarDerivativeOp(R2.dx, []))
raises(ValueError, lambda: CovarDerivativeOp(R2.x, []))
a = Symbol('a')
raises(ValueError, lambda: intcurve_series(R2.dx, a, R2_r.point([1, 2])))
raises(ValueError, lambda: intcurve_series(R2.x, a, R2_r.point([1, 2])))
raises(ValueError, lambda: intcurve_diffequ(R2.dx, a, R2_r.point([1, 2])))
raises(ValueError, lambda: intcurve_diffequ(R2.x, a, R2_r.point([1, 2])))
raises(ValueError, lambda: contravariant_order(R2.e_x + R2.dx))
raises(ValueError, lambda: covariant_order(R2.e_x + R2.dx))
raises(ValueError, lambda: contravariant_order(R2.e_x*R2.e_y))
raises(ValueError, lambda: covariant_order(R2.dx*R2.dy))
def test_simplify():
x, y = R2_r.coord_functions()
dx, dy = R2_r.base_oneforms()
ex, ey = R2_r.base_vectors()
assert simplify(x) == x
assert simplify(x*y) == x*y
assert simplify(dx*dy) == dx*dy
assert simplify(ex*ey) == ex*ey
assert ((1-x)*dx)/(1-x)**2 == dx/(1-x)
|
1652395cfdfd2b7902d5058a43e40a933350c3c4d13a38f998a5c984ad545367 | from sympy.core.symbol import symbols
from sympy.printing.codeprinter import ccode
from sympy.codegen.ast import Declaration, Variable, float64, int64, String, CodeBlock
from sympy.codegen.cnodes import (
alignof, CommaOperator, goto, Label, PreDecrement, PostDecrement, PreIncrement, PostIncrement,
sizeof, union, struct
)
x, y = symbols('x y')
def test_alignof():
ax = alignof(x)
assert ccode(ax) == 'alignof(x)'
assert ax.func(*ax.args) == ax
def test_CommaOperator():
expr = CommaOperator(PreIncrement(x), 2*x)
assert ccode(expr) == '(++(x), 2*x)'
assert expr.func(*expr.args) == expr
def test_goto_Label():
s = 'early_exit'
g = goto(s)
assert g.func(*g.args) == g
assert g != goto('foobar')
assert ccode(g) == 'goto early_exit'
l1 = Label(s)
assert ccode(l1) == 'early_exit:'
assert l1 == Label('early_exit')
assert l1 != Label('foobar')
body = [PreIncrement(x)]
l2 = Label(s, body)
assert l2.name == String("early_exit")
assert l2.body == CodeBlock(PreIncrement(x))
assert ccode(l2) == ("early_exit:\n"
"++(x);")
body = [PreIncrement(x), PreDecrement(y)]
l2 = Label(s, body)
assert l2.name == String("early_exit")
assert l2.body == CodeBlock(PreIncrement(x), PreDecrement(y))
assert ccode(l2) == ("early_exit:\n"
"{\n ++(x);\n --(y);\n}")
def test_PreDecrement():
p = PreDecrement(x)
assert p.func(*p.args) == p
assert ccode(p) == '--(x)'
def test_PostDecrement():
p = PostDecrement(x)
assert p.func(*p.args) == p
assert ccode(p) == '(x)--'
def test_PreIncrement():
p = PreIncrement(x)
assert p.func(*p.args) == p
assert ccode(p) == '++(x)'
def test_PostIncrement():
p = PostIncrement(x)
assert p.func(*p.args) == p
assert ccode(p) == '(x)++'
def test_sizeof():
typename = 'unsigned int'
sz = sizeof(typename)
assert ccode(sz) == 'sizeof(%s)' % typename
assert sz.func(*sz.args) == sz
assert not sz.is_Atom
assert sz.atoms() == {String('unsigned int'), String('sizeof')}
def test_struct():
vx, vy = Variable(x, type=float64), Variable(y, type=float64)
s = struct('vec2', [vx, vy])
assert s.func(*s.args) == s
assert s == struct('vec2', (vx, vy))
assert s != struct('vec2', (vy, vx))
assert str(s.name) == 'vec2'
assert len(s.declarations) == 2
assert all(isinstance(arg, Declaration) for arg in s.declarations)
assert ccode(s) == (
"struct vec2 {\n"
" double x;\n"
" double y;\n"
"}")
def test_union():
vx, vy = Variable(x, type=float64), Variable(y, type=int64)
u = union('dualuse', [vx, vy])
assert u.func(*u.args) == u
assert u == union('dualuse', (vx, vy))
assert str(u.name) == 'dualuse'
assert len(u.declarations) == 2
assert all(isinstance(arg, Declaration) for arg in u.declarations)
assert ccode(u) == (
"union dualuse {\n"
" double x;\n"
" int64_t y;\n"
"}")
|
b8d5aaf1762f0cc0d618348a7c58d4b79dd4b1760ef5714018cb916b58052831 | import os
import tempfile
from sympy import Symbol, symbols
from sympy.codegen.ast import (
Assignment, Print, Declaration, FunctionDefinition, Return, real,
FunctionCall, Variable, Element, integer
)
from sympy.codegen.fnodes import (
allocatable, ArrayConstructor, isign, dsign, cmplx, kind, literal_dp,
Program, Module, use, Subroutine, dimension, assumed_extent, ImpliedDoLoop,
intent_out, size, Do, SubroutineCall, sum_, array, bind_C
)
from sympy.codegen.futils import render_as_module
from sympy.core.expr import unchanged
from sympy.external import import_module
from sympy.printing.codeprinter import fcode
from sympy.utilities._compilation import has_fortran, compile_run_strings, compile_link_import_strings
from sympy.utilities._compilation.util import may_xfail
from sympy.testing.pytest import skip, XFAIL
cython = import_module('cython')
np = import_module('numpy')
def test_size():
x = Symbol('x', real=True)
sx = size(x)
assert fcode(sx, source_format='free') == 'size(x)'
@may_xfail
def test_size_assumed_shape():
if not has_fortran():
skip("No fortran compiler found.")
a = Symbol('a', real=True)
body = [Return((sum_(a**2)/size(a))**.5)]
arr = array(a, dim=[':'], intent='in')
fd = FunctionDefinition(real, 'rms', [arr], body)
render_as_module([fd], 'mod_rms')
(stdout, stderr), info = compile_run_strings([
('rms.f90', render_as_module([fd], 'mod_rms')),
('main.f90', (
'program myprog\n'
'use mod_rms, only: rms\n'
'real*8, dimension(4), parameter :: x = [4, 2, 2, 2]\n'
'print *, dsqrt(7d0) - rms(x)\n'
'end program\n'
))
], clean=True)
assert '0.00000' in stdout
assert stderr == ''
assert info['exit_status'] == os.EX_OK
@XFAIL # https://github.com/sympy/sympy/issues/20265
@may_xfail
def test_ImpliedDoLoop():
if not has_fortran():
skip("No fortran compiler found.")
a, i = symbols('a i', integer=True)
idl = ImpliedDoLoop(i**3, i, -3, 3, 2)
ac = ArrayConstructor([-28, idl, 28])
a = array(a, dim=[':'], attrs=[allocatable])
prog = Program('idlprog', [
a.as_Declaration(),
Assignment(a, ac),
Print([a])
])
fsrc = fcode(prog, standard=2003, source_format='free')
(stdout, stderr), info = compile_run_strings([('main.f90', fsrc)], clean=True)
for numstr in '-28 -27 -1 1 27 28'.split():
assert numstr in stdout
assert stderr == ''
assert info['exit_status'] == os.EX_OK
@may_xfail
def test_Program():
x = Symbol('x', real=True)
vx = Variable.deduced(x, 42)
decl = Declaration(vx)
prnt = Print([x, x+1])
prog = Program('foo', [decl, prnt])
if not has_fortran():
skip("No fortran compiler found.")
(stdout, stderr), info = compile_run_strings([('main.f90', fcode(prog, standard=90))], clean=True)
assert '42' in stdout
assert '43' in stdout
assert stderr == ''
assert info['exit_status'] == os.EX_OK
@may_xfail
def test_Module():
x = Symbol('x', real=True)
v_x = Variable.deduced(x)
sq = FunctionDefinition(real, 'sqr', [v_x], [Return(x**2)])
mod_sq = Module('mod_sq', [], [sq])
sq_call = FunctionCall('sqr', [42.])
prg_sq = Program('foobar', [
use('mod_sq', only=['sqr']),
Print(['"Square of 42 = "', sq_call])
])
if not has_fortran():
skip("No fortran compiler found.")
(stdout, stderr), info = compile_run_strings([
('mod_sq.f90', fcode(mod_sq, standard=90)),
('main.f90', fcode(prg_sq, standard=90))
], clean=True)
assert '42' in stdout
assert str(42**2) in stdout
assert stderr == ''
@XFAIL # https://github.com/sympy/sympy/issues/20265
@may_xfail
def test_Subroutine():
# Code to generate the subroutine in the example from
# http://www.fortran90.org/src/best-practices.html#arrays
r = Symbol('r', real=True)
i = Symbol('i', integer=True)
v_r = Variable.deduced(r, attrs=(dimension(assumed_extent), intent_out))
v_i = Variable.deduced(i)
v_n = Variable('n', integer)
do_loop = Do([
Assignment(Element(r, [i]), literal_dp(1)/i**2)
], i, 1, v_n)
sub = Subroutine("f", [v_r], [
Declaration(v_n),
Declaration(v_i),
Assignment(v_n, size(r)),
do_loop
])
x = Symbol('x', real=True)
v_x3 = Variable.deduced(x, attrs=[dimension(3)])
mod = Module('mymod', definitions=[sub])
prog = Program('foo', [
use(mod, only=[sub]),
Declaration(v_x3),
SubroutineCall(sub, [v_x3]),
Print([sum_(v_x3), v_x3])
])
if not has_fortran():
skip("No fortran compiler found.")
(stdout, stderr), info = compile_run_strings([
('a.f90', fcode(mod, standard=90)),
('b.f90', fcode(prog, standard=90))
], clean=True)
ref = [1.0/i**2 for i in range(1, 4)]
assert str(sum(ref))[:-3] in stdout
for _ in ref:
assert str(_)[:-3] in stdout
assert stderr == ''
def test_isign():
x = Symbol('x', integer=True)
assert unchanged(isign, 1, x)
assert fcode(isign(1, x), standard=95, source_format='free') == 'isign(1, x)'
def test_dsign():
x = Symbol('x')
assert unchanged(dsign, 1, x)
assert fcode(dsign(literal_dp(1), x), standard=95, source_format='free') == 'dsign(1d0, x)'
def test_cmplx():
x = Symbol('x')
assert unchanged(cmplx, 1, x)
def test_kind():
x = Symbol('x')
assert unchanged(kind, x)
def test_literal_dp():
assert fcode(literal_dp(0), source_format='free') == '0d0'
@may_xfail
def test_bind_C():
if not has_fortran():
skip("No fortran compiler found.")
if not cython:
skip("Cython not found.")
if not np:
skip("NumPy not found.")
a = Symbol('a', real=True)
s = Symbol('s', integer=True)
body = [Return((sum_(a**2)/s)**.5)]
arr = array(a, dim=[s], intent='in')
fd = FunctionDefinition(real, 'rms', [arr, s], body, attrs=[bind_C('rms')])
f_mod = render_as_module([fd], 'mod_rms')
with tempfile.TemporaryDirectory() as folder:
mod, info = compile_link_import_strings([
('rms.f90', f_mod),
('_rms.pyx', (
"#cython: language_level={}\n".format("3") +
"cdef extern double rms(double*, int*)\n"
"def py_rms(double[::1] x):\n"
" cdef int s = x.size\n"
" return rms(&x[0], &s)\n"))
], build_dir=folder)
assert abs(mod.py_rms(np.array([2., 4., 2., 2.])) - 7**0.5) < 1e-14
|
e4ec0df03fd9b4a37dcf9b8d794c1b524c801b334bad380829495c45698e4a91 | from sympy.core.symbol import Symbol
from sympy.codegen.ast import Type
from sympy.codegen.cxxnodes import using
from sympy.printing.codeprinter import cxxcode
x = Symbol('x')
def test_using():
v = Type('std::vector')
u1 = using(v)
assert cxxcode(u1) == 'using std::vector'
u2 = using(v, 'vec')
assert cxxcode(u2) == 'using vec = std::vector'
|
60277c87ed4f4b27efd9fb24d60b80de935e2fd9664f4c69aaa75590c6620a3c | import tempfile
from sympy import log, exp, cos, S, Symbol, Pow, sin, MatrixSymbol, sinc, pi
from sympy.assumptions import assuming, Q
from sympy.external import import_module
from sympy.printing.codeprinter import ccode
from sympy.codegen.matrix_nodes import MatrixSolve
from sympy.codegen.cfunctions import log2, exp2, expm1, log1p
from sympy.codegen.numpy_nodes import logaddexp, logaddexp2
from sympy.codegen.scipy_nodes import cosm1
from sympy.codegen.rewriting import (
optimize, cosm1_opt, log2_opt, exp2_opt, expm1_opt, log1p_opt, optims_c99,
create_expand_pow_optimization, matinv_opt, logaddexp_opt, logaddexp2_opt,
optims_numpy, sinc_opts, FuncMinusOneOptim
)
from sympy.testing.pytest import XFAIL, skip
from sympy.utilities._compilation import compile_link_import_strings, has_c
from sympy.utilities._compilation.util import may_xfail
cython = import_module('cython')
def test_log2_opt():
x = Symbol('x')
expr1 = 7*log(3*x + 5)/(log(2))
opt1 = optimize(expr1, [log2_opt])
assert opt1 == 7*log2(3*x + 5)
assert opt1.rewrite(log) == expr1
expr2 = 3*log(5*x + 7)/(13*log(2))
opt2 = optimize(expr2, [log2_opt])
assert opt2 == 3*log2(5*x + 7)/13
assert opt2.rewrite(log) == expr2
expr3 = log(x)/log(2)
opt3 = optimize(expr3, [log2_opt])
assert opt3 == log2(x)
assert opt3.rewrite(log) == expr3
expr4 = log(x)/log(2) + log(x+1)
opt4 = optimize(expr4, [log2_opt])
assert opt4 == log2(x) + log(2)*log2(x+1)
assert opt4.rewrite(log) == expr4
expr5 = log(17)
opt5 = optimize(expr5, [log2_opt])
assert opt5 == expr5
expr6 = log(x + 3)/log(2)
opt6 = optimize(expr6, [log2_opt])
assert str(opt6) == 'log2(x + 3)'
assert opt6.rewrite(log) == expr6
def test_exp2_opt():
x = Symbol('x')
expr1 = 1 + 2**x
opt1 = optimize(expr1, [exp2_opt])
assert opt1 == 1 + exp2(x)
assert opt1.rewrite(Pow) == expr1
expr2 = 1 + 3**x
assert expr2 == optimize(expr2, [exp2_opt])
def test_expm1_opt():
x = Symbol('x')
expr1 = exp(x) - 1
opt1 = optimize(expr1, [expm1_opt])
assert expm1(x) - opt1 == 0
assert opt1.rewrite(exp) == expr1
expr2 = 3*exp(x) - 3
opt2 = optimize(expr2, [expm1_opt])
assert 3*expm1(x) == opt2
assert opt2.rewrite(exp) == expr2
expr3 = 3*exp(x) - 5
opt3 = optimize(expr3, [expm1_opt])
assert 3*expm1(x) - 2 == opt3
assert opt3.rewrite(exp) == expr3
expm1_opt_non_opportunistic = FuncMinusOneOptim(exp, expm1, opportunistic=False)
assert expr3 == optimize(expr3, [expm1_opt_non_opportunistic])
assert opt1 == optimize(expr1, [expm1_opt_non_opportunistic])
assert opt2 == optimize(expr2, [expm1_opt_non_opportunistic])
expr4 = 3*exp(x) + log(x) - 3
opt4 = optimize(expr4, [expm1_opt])
assert 3*expm1(x) + log(x) == opt4
assert opt4.rewrite(exp) == expr4
expr5 = 3*exp(2*x) - 3
opt5 = optimize(expr5, [expm1_opt])
assert 3*expm1(2*x) == opt5
assert opt5.rewrite(exp) == expr5
expr6 = (2*exp(x) + 1)/(exp(x) + 1) + 1
opt6 = optimize(expr6, [expm1_opt])
assert opt6.count_ops() <= expr6.count_ops()
def ev(e):
return e.subs(x, 3).evalf()
assert abs(ev(expr6) - ev(opt6)) < 1e-15
y = Symbol('y')
expr7 = (2*exp(x) - 1)/(1 - exp(y)) - 1/(1-exp(y))
opt7 = optimize(expr7, [expm1_opt])
assert -2*expm1(x)/expm1(y) == opt7
assert (opt7.rewrite(exp) - expr7).factor() == 0
expr8 = (1+exp(x))**2 - 4
opt8 = optimize(expr8, [expm1_opt])
tgt8a = (exp(x) + 3)*expm1(x)
tgt8b = 2*expm1(x) + expm1(2*x)
# Both tgt8a & tgt8b seem to give full precision (~16 digits for double)
# for x=1e-7 (compare with expr8 which only achieves ~8 significant digits).
# If we can show that either tgt8a or tgt8b is preferable, we can
# change this test to ensure the preferable version is returned.
assert (tgt8a - tgt8b).rewrite(exp).factor() == 0
assert opt8 in (tgt8a, tgt8b)
assert (opt8.rewrite(exp) - expr8).factor() == 0
expr9 = sin(expr8)
opt9 = optimize(expr9, [expm1_opt])
tgt9a = sin(tgt8a)
tgt9b = sin(tgt8b)
assert opt9 in (tgt9a, tgt9b)
assert (opt9.rewrite(exp) - expr9.rewrite(exp)).factor().is_zero
def test_expm1_two_exp_terms():
x, y = map(Symbol, 'x y'.split())
expr1 = exp(x) + exp(y) - 2
opt1 = optimize(expr1, [expm1_opt])
assert opt1 == expm1(x) + expm1(y)
def test_cosm1_opt():
x = Symbol('x')
expr1 = cos(x) - 1
opt1 = optimize(expr1, [cosm1_opt])
assert cosm1(x) - opt1 == 0
assert opt1.rewrite(cos) == expr1
expr2 = 3*cos(x) - 3
opt2 = optimize(expr2, [cosm1_opt])
assert 3*cosm1(x) == opt2
assert opt2.rewrite(cos) == expr2
expr3 = 3*cos(x) - 5
opt3 = optimize(expr3, [cosm1_opt])
assert 3*cosm1(x) - 2 == opt3
assert opt3.rewrite(cos) == expr3
cosm1_opt_non_opportunistic = FuncMinusOneOptim(cos, cosm1, opportunistic=False)
assert expr3 == optimize(expr3, [cosm1_opt_non_opportunistic])
assert opt1 == optimize(expr1, [cosm1_opt_non_opportunistic])
assert opt2 == optimize(expr2, [cosm1_opt_non_opportunistic])
expr4 = 3*cos(x) + log(x) - 3
opt4 = optimize(expr4, [cosm1_opt])
assert 3*cosm1(x) + log(x) == opt4
assert opt4.rewrite(cos) == expr4
expr5 = 3*cos(2*x) - 3
opt5 = optimize(expr5, [cosm1_opt])
assert 3*cosm1(2*x) == opt5
assert opt5.rewrite(cos) == expr5
expr6 = 2 - 2*cos(x)
opt6 = optimize(expr6, [cosm1_opt])
assert -2*cosm1(x) == opt6
assert opt6.rewrite(cos) == expr6
def test_cosm1_two_cos_terms():
x, y = map(Symbol, 'x y'.split())
expr1 = cos(x) + cos(y) - 2
opt1 = optimize(expr1, [cosm1_opt])
assert opt1 == cosm1(x) + cosm1(y)
def test_expm1_cosm1_mixed():
x = Symbol('x')
expr1 = exp(x) + cos(x) - 2
opt1 = optimize(expr1, [expm1_opt, cosm1_opt])
assert opt1 == cosm1(x) + expm1(x)
def test_log1p_opt():
x = Symbol('x')
expr1 = log(x + 1)
opt1 = optimize(expr1, [log1p_opt])
assert log1p(x) - opt1 == 0
assert opt1.rewrite(log) == expr1
expr2 = log(3*x + 3)
opt2 = optimize(expr2, [log1p_opt])
assert log1p(x) + log(3) == opt2
assert (opt2.rewrite(log) - expr2).simplify() == 0
expr3 = log(2*x + 1)
opt3 = optimize(expr3, [log1p_opt])
assert log1p(2*x) - opt3 == 0
assert opt3.rewrite(log) == expr3
expr4 = log(x+3)
opt4 = optimize(expr4, [log1p_opt])
assert str(opt4) == 'log(x + 3)'
def test_optims_c99():
x = Symbol('x')
expr1 = 2**x + log(x)/log(2) + log(x + 1) + exp(x) - 1
opt1 = optimize(expr1, optims_c99).simplify()
assert opt1 == exp2(x) + log2(x) + log1p(x) + expm1(x)
assert opt1.rewrite(exp).rewrite(log).rewrite(Pow) == expr1
expr2 = log(x)/log(2) + log(x + 1)
opt2 = optimize(expr2, optims_c99)
assert opt2 == log2(x) + log1p(x)
assert opt2.rewrite(log) == expr2
expr3 = log(x)/log(2) + log(17*x + 17)
opt3 = optimize(expr3, optims_c99)
delta3 = opt3 - (log2(x) + log(17) + log1p(x))
assert delta3 == 0
assert (opt3.rewrite(log) - expr3).simplify() == 0
expr4 = 2**x + 3*log(5*x + 7)/(13*log(2)) + 11*exp(x) - 11 + log(17*x + 17)
opt4 = optimize(expr4, optims_c99).simplify()
delta4 = opt4 - (exp2(x) + 3*log2(5*x + 7)/13 + 11*expm1(x) + log(17) + log1p(x))
assert delta4 == 0
assert (opt4.rewrite(exp).rewrite(log).rewrite(Pow) - expr4).simplify() == 0
expr5 = 3*exp(2*x) - 3
opt5 = optimize(expr5, optims_c99)
delta5 = opt5 - 3*expm1(2*x)
assert delta5 == 0
assert opt5.rewrite(exp) == expr5
expr6 = exp(2*x) - 3
opt6 = optimize(expr6, optims_c99)
assert opt6 in (expm1(2*x) - 2, expr6) # expm1(2*x) - 2 is not better or worse
expr7 = log(3*x + 3)
opt7 = optimize(expr7, optims_c99)
delta7 = opt7 - (log(3) + log1p(x))
assert delta7 == 0
assert (opt7.rewrite(log) - expr7).simplify() == 0
expr8 = log(2*x + 3)
opt8 = optimize(expr8, optims_c99)
assert opt8 == expr8
def test_create_expand_pow_optimization():
cc = lambda x: ccode(
optimize(x, [create_expand_pow_optimization(4)]))
x = Symbol('x')
assert cc(x**4) == 'x*x*x*x'
assert cc(x**4 + x**2) == 'x*x + x*x*x*x'
assert cc(x**5 + x**4) == 'pow(x, 5) + x*x*x*x'
assert cc(sin(x)**4) == 'pow(sin(x), 4)'
# gh issue 15335
assert cc(x**(-4)) == '1.0/(x*x*x*x)'
assert cc(x**(-5)) == 'pow(x, -5)'
assert cc(-x**4) == '-x*x*x*x'
assert cc(x**4 - x**2) == '-x*x + x*x*x*x'
i = Symbol('i', integer=True)
assert cc(x**i - x**2) == 'pow(x, i) - x*x'
# gh issue 20753
cc2 = lambda x: ccode(optimize(x, [create_expand_pow_optimization(
4, base_req=lambda b: b.is_Function)]))
assert cc2(x**3 + sin(x)**3) == "pow(x, 3) + sin(x)*sin(x)*sin(x)"
def test_matsolve():
n = Symbol('n', integer=True)
A = MatrixSymbol('A', n, n)
x = MatrixSymbol('x', n, 1)
with assuming(Q.fullrank(A)):
assert optimize(A**(-1) * x, [matinv_opt]) == MatrixSolve(A, x)
assert optimize(A**(-1) * x + x, [matinv_opt]) == MatrixSolve(A, x) + x
def test_logaddexp_opt():
x, y = map(Symbol, 'x y'.split())
expr1 = log(exp(x) + exp(y))
opt1 = optimize(expr1, [logaddexp_opt])
assert logaddexp(x, y) - opt1 == 0
assert logaddexp(y, x) - opt1 == 0
assert opt1.rewrite(log) == expr1
def test_logaddexp2_opt():
x, y = map(Symbol, 'x y'.split())
expr1 = log(2**x + 2**y)/log(2)
opt1 = optimize(expr1, [logaddexp2_opt])
assert logaddexp2(x, y) - opt1 == 0
assert logaddexp2(y, x) - opt1 == 0
assert opt1.rewrite(log) == expr1
def test_sinc_opts():
def check(d):
for k, v in d.items():
assert optimize(k, sinc_opts) == v
x = Symbol('x')
check({
sin(x)/x : sinc(x),
sin(2*x)/(2*x) : sinc(2*x),
sin(3*x)/x : 3*sinc(3*x),
x*sin(x) : x*sin(x)
})
y = Symbol('y')
check({
sin(x*y)/(x*y) : sinc(x*y),
y*sin(x/y)/x : sinc(x/y),
sin(sin(x))/sin(x) : sinc(sin(x)),
sin(3*sin(x))/sin(x) : 3*sinc(3*sin(x)),
sin(x)/y : sin(x)/y
})
def test_optims_numpy():
def check(d):
for k, v in d.items():
assert optimize(k, optims_numpy) == v
x = Symbol('x')
check({
sin(2*x)/(2*x) + exp(2*x) - 1: sinc(2*x) + expm1(2*x),
log(x+3)/log(2) + log(x**2 + 1): log1p(x**2) + log2(x+3)
})
@XFAIL # room for improvement, ideally this test case should pass.
def test_optims_numpy_TODO():
def check(d):
for k, v in d.items():
assert optimize(k, optims_numpy) == v
x, y = map(Symbol, 'x y'.split())
check({
log(x*y)*sin(x*y)*log(x*y+1)/(log(2)*x*y): log2(x*y)*sinc(x*y)*log1p(x*y),
exp(x*sin(y)/y) - 1: expm1(x*sinc(y))
})
@may_xfail
def test_compiled_ccode_with_rewriting():
if not cython:
skip("cython not installed.")
if not has_c():
skip("No C compiler found.")
x = Symbol('x')
about_two = 2**(58/S(117))*3**(97/S(117))*5**(4/S(39))*7**(92/S(117))/S(30)*pi
# about_two: 1.999999999999581826
unchanged = 2*exp(x) - about_two
xval = S(10)**-11
ref = unchanged.subs(x, xval).n(19) # 2.0418173913673213e-11
rewritten = optimize(2*exp(x) - about_two, [expm1_opt])
# Unfortunately, we need to call ``.n()`` on our expressions before we hand them
# to ``ccode``, and we need to request a large number of significant digits.
# In this test, results converged for double precision when the following number
# of significant digits were chosen:
NUMBER_OF_DIGITS = 25 # TODO: this should ideally be automatically handled.
func_c = '''
#include <math.h>
double func_unchanged(double x) {
return %(unchanged)s;
}
double func_rewritten(double x) {
return %(rewritten)s;
}
''' % dict(unchanged=ccode(unchanged.n(NUMBER_OF_DIGITS)),
rewritten=ccode(rewritten.n(NUMBER_OF_DIGITS)))
func_pyx = '''
#cython: language_level=3
cdef extern double func_unchanged(double)
cdef extern double func_rewritten(double)
def py_unchanged(x):
return func_unchanged(x)
def py_rewritten(x):
return func_rewritten(x)
'''
with tempfile.TemporaryDirectory() as folder:
mod, info = compile_link_import_strings(
[('func.c', func_c), ('_func.pyx', func_pyx)],
build_dir=folder, compile_kwargs=dict(std='c99')
)
err_rewritten = abs(mod.py_rewritten(1e-11) - ref)
err_unchanged = abs(mod.py_unchanged(1e-11) - ref)
assert 1e-27 < err_rewritten < 1e-25 # highly accurate.
assert 1e-19 < err_unchanged < 1e-16 # quite poor.
# Tolerances used above were determined as follows:
# >>> no_opt = unchanged.subs(x, xval.evalf()).evalf()
# >>> with_opt = rewritten.n(25).subs(x, 1e-11).evalf()
# >>> with_opt - ref, no_opt - ref
# (1.1536301877952077e-26, 1.6547074214222335e-18)
|
baf9502df18075d93a2deeee9df1434c0668a74acfe2b95ac45b401e86630e59 | import tempfile
import sympy as sp
from sympy.codegen.ast import Assignment
from sympy.codegen.algorithms import newtons_method, newtons_method_function
from sympy.codegen.fnodes import bind_C
from sympy.codegen.futils import render_as_module as f_module
from sympy.codegen.pyutils import render_as_module as py_module
from sympy.external import import_module
from sympy.printing.codeprinter import ccode
from sympy.utilities._compilation import compile_link_import_strings, has_c, has_fortran
from sympy.utilities._compilation.util import may_xfail
from sympy.testing.pytest import skip, raises
cython = import_module('cython')
wurlitzer = import_module('wurlitzer')
def test_newtons_method():
x, dx, atol = sp.symbols('x dx atol')
expr = sp.cos(x) - x**3
algo = newtons_method(expr, x, atol, dx)
assert algo.has(Assignment(dx, -expr/expr.diff(x)))
@may_xfail
def test_newtons_method_function__ccode():
x = sp.Symbol('x', real=True)
expr = sp.cos(x) - x**3
func = newtons_method_function(expr, x)
if not cython:
skip("cython not installed.")
if not has_c():
skip("No C compiler found.")
compile_kw = dict(std='c99')
with tempfile.TemporaryDirectory() as folder:
mod, info = compile_link_import_strings([
('newton.c', ('#include <math.h>\n'
'#include <stdio.h>\n') + ccode(func)),
('_newton.pyx', ("#cython: language_level={}\n".format("3") +
"cdef extern double newton(double)\n"
"def py_newton(x):\n"
" return newton(x)\n"))
], build_dir=folder, compile_kwargs=compile_kw)
assert abs(mod.py_newton(0.5) - 0.865474033102) < 1e-12
@may_xfail
def test_newtons_method_function__fcode():
x = sp.Symbol('x', real=True)
expr = sp.cos(x) - x**3
func = newtons_method_function(expr, x, attrs=[bind_C(name='newton')])
if not cython:
skip("cython not installed.")
if not has_fortran():
skip("No Fortran compiler found.")
f_mod = f_module([func], 'mod_newton')
with tempfile.TemporaryDirectory() as folder:
mod, info = compile_link_import_strings([
('newton.f90', f_mod),
('_newton.pyx', ("#cython: language_level={}\n".format("3") +
"cdef extern double newton(double*)\n"
"def py_newton(double x):\n"
" return newton(&x)\n"))
], build_dir=folder)
assert abs(mod.py_newton(0.5) - 0.865474033102) < 1e-12
def test_newtons_method_function__pycode():
x = sp.Symbol('x', real=True)
expr = sp.cos(x) - x**3
func = newtons_method_function(expr, x)
py_mod = py_module(func)
namespace = {}
exec(py_mod, namespace, namespace)
res = eval('newton(0.5)', namespace)
assert abs(res - 0.865474033102) < 1e-12
@may_xfail
def test_newtons_method_function__ccode_parameters():
args = x, A, k, p = sp.symbols('x A k p')
expr = A*sp.cos(k*x) - p*x**3
raises(ValueError, lambda: newtons_method_function(expr, x))
use_wurlitzer = wurlitzer
func = newtons_method_function(expr, x, args, debug=use_wurlitzer)
if not has_c():
skip("No C compiler found.")
if not cython:
skip("cython not installed.")
compile_kw = dict(std='c99')
with tempfile.TemporaryDirectory() as folder:
mod, info = compile_link_import_strings([
('newton_par.c', ('#include <math.h>\n'
'#include <stdio.h>\n') + ccode(func)),
('_newton_par.pyx', ("#cython: language_level={}\n".format("3") +
"cdef extern double newton(double, double, double, double)\n"
"def py_newton(x, A=1, k=1, p=1):\n"
" return newton(x, A, k, p)\n"))
], compile_kwargs=compile_kw, build_dir=folder)
if use_wurlitzer:
with wurlitzer.pipes() as (out, err):
result = mod.py_newton(0.5)
else:
result = mod.py_newton(0.5)
assert abs(result - 0.865474033102) < 1e-12
if not use_wurlitzer:
skip("C-level output only tested when package 'wurlitzer' is available.")
out, err = out.read(), err.read()
assert err == ''
assert out == """\
x= 0.5 d_x= 0.61214
x= 1.1121 d_x= -0.20247
x= 0.90967 d_x= -0.042409
x= 0.86726 d_x= -0.0017867
x= 0.86548 d_x= -3.1022e-06
x= 0.86547 d_x= -9.3421e-12
x= 0.86547 d_x= 3.6902e-17
""" # try to run tests with LC_ALL=C if this assertion fails
|
40fcdf83c3bc4cc1d5c1e541a45064179555f6d000fe28dc6a07ffdc24a5eeb9 | # This file contains tests that exercise multiple AST nodes
import tempfile
from sympy.external import import_module
from sympy.printing.codeprinter import ccode
from sympy.utilities._compilation import compile_link_import_strings, has_c
from sympy.utilities._compilation.util import may_xfail
from sympy.testing.pytest import skip
from sympy.codegen.ast import (
FunctionDefinition, FunctionPrototype, Variable, Pointer, real, Assignment,
integer, CodeBlock, While
)
from sympy.codegen.cnodes import void, PreIncrement
from sympy.codegen.cutils import render_as_source_file
cython = import_module('cython')
np = import_module('numpy')
def _mk_func1():
declars = n, inp, out = Variable('n', integer), Pointer('inp', real), Pointer('out', real)
i = Variable('i', integer)
whl = While(i<n, [Assignment(out[i], inp[i]), PreIncrement(i)])
body = CodeBlock(i.as_Declaration(value=0), whl)
return FunctionDefinition(void, 'our_test_function', declars, body)
def _render_compile_import(funcdef, build_dir):
code_str = render_as_source_file(funcdef, settings=dict(contract=False))
declar = ccode(FunctionPrototype.from_FunctionDefinition(funcdef))
return compile_link_import_strings([
('our_test_func.c', code_str),
('_our_test_func.pyx', ("#cython: language_level={}\n".format("3") +
"cdef extern {declar}\n"
"def _{fname}({typ}[:] inp, {typ}[:] out):\n"
" {fname}(inp.size, &inp[0], &out[0])").format(
declar=declar, fname=funcdef.name, typ='double'
))
], build_dir=build_dir)
@may_xfail
def test_copying_function():
if not np:
skip("numpy not installed.")
if not has_c():
skip("No C compiler found.")
if not cython:
skip("Cython not found.")
info = None
with tempfile.TemporaryDirectory() as folder:
mod, info = _render_compile_import(_mk_func1(), build_dir=folder)
inp = np.arange(10.0)
out = np.empty_like(inp)
mod._our_test_function(inp, out)
assert np.allclose(inp, out)
|
dd24108cec6391c218126792def1d5ef2e89145349a2cf5d4ecde1a42d556f86 | """
Handlers for predicates related to set membership: integer, rational, etc.
"""
from sympy.assumptions import Q, ask
from sympy.core import Add, Basic, Expr, Mul, Pow
from sympy.core.numbers import (AlgebraicNumber, ComplexInfinity, Exp1, Float,
GoldenRatio, ImaginaryUnit, Infinity, Integer, NaN, NegativeInfinity,
Number, NumberSymbol, Pi, pi, Rational, TribonacciConstant, E)
from sympy.core.logic import fuzzy_bool
from sympy.functions import (Abs, acos, acot, asin, atan, cos, cot, exp, im,
log, re, sin, tan)
from sympy import I, Eq, conjugate
from sympy.matrices import Determinant, MatrixBase, Trace
from sympy.matrices.expressions.matexpr import MatrixElement
from sympy.multipledispatch import MDNotImplementedError
from .common import test_closed_group
from ..predicates.sets import (IntegerPredicate, RationalPredicate,
IrrationalPredicate, RealPredicate, ExtendedRealPredicate,
HermitianPredicate, ComplexPredicate, ImaginaryPredicate,
AntihermitianPredicate, AlgebraicPredicate)
# IntegerPredicate
def _IntegerPredicate_number(expr, assumptions):
# helper function
try:
i = int(expr.round())
if not (expr - i).equals(0):
raise TypeError
return True
except TypeError:
return False
@IntegerPredicate.register_many(int, Integer)
def _(expr, assumptions):
return True
@IntegerPredicate.register_many(Exp1, GoldenRatio, ImaginaryUnit, Infinity,
NegativeInfinity, Pi, Rational, TribonacciConstant)
def _(expr, assumptions):
return False
@IntegerPredicate.register(Expr)
def _(expr, assumptions):
ret = expr.is_integer
if ret is None:
raise MDNotImplementedError
return ret
@IntegerPredicate.register_many(Add, Pow)
def _(expr, assumptions):
"""
* Integer + Integer -> Integer
* Integer + !Integer -> !Integer
* !Integer + !Integer -> ?
"""
if expr.is_number:
return _IntegerPredicate_number(expr, assumptions)
return test_closed_group(expr, assumptions, Q.integer)
@IntegerPredicate.register(Mul)
def _(expr, assumptions):
"""
* Integer*Integer -> Integer
* Integer*Irrational -> !Integer
* Odd/Even -> !Integer
* Integer*Rational -> ?
"""
if expr.is_number:
return _IntegerPredicate_number(expr, assumptions)
_output = True
for arg in expr.args:
if not ask(Q.integer(arg), assumptions):
if arg.is_Rational:
if arg.q == 2:
return ask(Q.even(2*expr), assumptions)
if ~(arg.q & 1):
return None
elif ask(Q.irrational(arg), assumptions):
if _output:
_output = False
else:
return
else:
return
return _output
@IntegerPredicate.register(Abs)
def _(expr, assumptions):
return ask(Q.integer(expr.args[0]), assumptions)
@IntegerPredicate.register_many(Determinant, MatrixElement, Trace)
def _(expr, assumptions):
return ask(Q.integer_elements(expr.args[0]), assumptions)
# RationalPredicate
@RationalPredicate.register(Rational)
def _(expr, assumptions):
return True
@RationalPredicate.register(Float)
def _(expr, assumptions):
return None
@RationalPredicate.register_many(Exp1, GoldenRatio, ImaginaryUnit, Infinity,
NegativeInfinity, Pi, TribonacciConstant)
def _(expr, assumptions):
return False
@RationalPredicate.register(Expr)
def _(expr, assumptions):
ret = expr.is_rational
if ret is None:
raise MDNotImplementedError
return ret
@RationalPredicate.register_many(Add, Mul)
def _(expr, assumptions):
"""
* Rational + Rational -> Rational
* Rational + !Rational -> !Rational
* !Rational + !Rational -> ?
"""
if expr.is_number:
if expr.as_real_imag()[1]:
return False
return test_closed_group(expr, assumptions, Q.rational)
@RationalPredicate.register(Pow)
def _(expr, assumptions):
"""
* Rational ** Integer -> Rational
* Irrational ** Rational -> Irrational
* Rational ** Irrational -> ?
"""
if expr.base == E:
x = expr.exp
if ask(Q.rational(x), assumptions):
return ask(~Q.nonzero(x), assumptions)
return
if ask(Q.integer(expr.exp), assumptions):
return ask(Q.rational(expr.base), assumptions)
elif ask(Q.rational(expr.exp), assumptions):
if ask(Q.prime(expr.base), assumptions):
return False
@RationalPredicate.register_many(asin, atan, cos, sin, tan)
def _(expr, assumptions):
x = expr.args[0]
if ask(Q.rational(x), assumptions):
return ask(~Q.nonzero(x), assumptions)
@RationalPredicate.register(exp)
def _(expr, assumptions):
x = expr.exp
if ask(Q.rational(x), assumptions):
return ask(~Q.nonzero(x), assumptions)
@RationalPredicate.register_many(acot, cot)
def _(expr, assumptions):
x = expr.args[0]
if ask(Q.rational(x), assumptions):
return False
@RationalPredicate.register_many(acos, log)
def _(expr, assumptions):
x = expr.args[0]
if ask(Q.rational(x), assumptions):
return ask(~Q.nonzero(x - 1), assumptions)
# IrrationalPredicate
@IrrationalPredicate.register(Expr)
def _(expr, assumptions):
ret = expr.is_irrational
if ret is None:
raise MDNotImplementedError
return ret
@IrrationalPredicate.register(Basic)
def _(expr, assumptions):
_real = ask(Q.real(expr), assumptions)
if _real:
_rational = ask(Q.rational(expr), assumptions)
if _rational is None:
return None
return not _rational
else:
return _real
# RealPredicate
def _RealPredicate_number(expr, assumptions):
# let as_real_imag() work first since the expression may
# be simpler to evaluate
i = expr.as_real_imag()[1].evalf(2)
if i._prec != 1:
return not i
# allow None to be returned if we couldn't show for sure
# that i was 0
@RealPredicate.register_many(Abs, Exp1, Float, GoldenRatio, im, Pi, Rational,
re, TribonacciConstant)
def _(expr, assumptions):
return True
@RealPredicate.register_many(ImaginaryUnit, Infinity, NegativeInfinity)
def _(expr, assumptions):
return False
@RealPredicate.register(Expr)
def _(expr, assumptions):
ret = expr.is_real
if ret is None:
raise MDNotImplementedError
return ret
@RealPredicate.register(Add)
def _(expr, assumptions):
"""
* Real + Real -> Real
* Real + (Complex & !Real) -> !Real
"""
if expr.is_number:
return _RealPredicate_number(expr, assumptions)
return test_closed_group(expr, assumptions, Q.real)
@RealPredicate.register(Mul)
def _(expr, assumptions):
"""
* Real*Real -> Real
* Real*Imaginary -> !Real
* Imaginary*Imaginary -> Real
"""
if expr.is_number:
return _RealPredicate_number(expr, assumptions)
result = True
for arg in expr.args:
if ask(Q.real(arg), assumptions):
pass
elif ask(Q.imaginary(arg), assumptions):
result = result ^ True
else:
break
else:
return result
@RealPredicate.register(Pow)
def _(expr, assumptions):
"""
* Real**Integer -> Real
* Positive**Real -> Real
* Real**(Integer/Even) -> Real if base is nonnegative
* Real**(Integer/Odd) -> Real
* Imaginary**(Integer/Even) -> Real
* Imaginary**(Integer/Odd) -> not Real
* Imaginary**Real -> ? since Real could be 0 (giving real)
or 1 (giving imaginary)
* b**Imaginary -> Real if log(b) is imaginary and b != 0
and exponent != integer multiple of
I*pi/log(b)
* Real**Real -> ? e.g. sqrt(-1) is imaginary and
sqrt(2) is not
"""
if expr.is_number:
return _RealPredicate_number(expr, assumptions)
if expr.base == E:
return ask(
Q.integer(expr.exp/I/pi) | Q.real(expr.exp), assumptions
)
if expr.base.func == exp or (expr.base.is_Pow and expr.base.base == E):
if ask(Q.imaginary(expr.base.exp), assumptions):
if ask(Q.imaginary(expr.exp), assumptions):
return True
# If the i = (exp's arg)/(I*pi) is an integer or half-integer
# multiple of I*pi then 2*i will be an integer. In addition,
# exp(i*I*pi) = (-1)**i so the overall realness of the expr
# can be determined by replacing exp(i*I*pi) with (-1)**i.
i = expr.base.exp/I/pi
if ask(Q.integer(2*i), assumptions):
return ask(Q.real(((-1)**i)**expr.exp), assumptions)
return
if ask(Q.imaginary(expr.base), assumptions):
if ask(Q.integer(expr.exp), assumptions):
odd = ask(Q.odd(expr.exp), assumptions)
if odd is not None:
return not odd
return
if ask(Q.imaginary(expr.exp), assumptions):
imlog = ask(Q.imaginary(log(expr.base)), assumptions)
if imlog is not None:
# I**i -> real, log(I) is imag;
# (2*I)**i -> complex, log(2*I) is not imag
return imlog
if ask(Q.real(expr.base), assumptions):
if ask(Q.real(expr.exp), assumptions):
if expr.exp.is_Rational and \
ask(Q.even(expr.exp.q), assumptions):
return ask(Q.positive(expr.base), assumptions)
elif ask(Q.integer(expr.exp), assumptions):
return True
elif ask(Q.positive(expr.base), assumptions):
return True
elif ask(Q.negative(expr.base), assumptions):
return False
@RealPredicate.register_many(cos, sin)
def _(expr, assumptions):
if ask(Q.real(expr.args[0]), assumptions):
return True
@RealPredicate.register(exp)
def _(expr, assumptions):
return ask(
Q.integer(expr.exp/I/pi) | Q.real(expr.exp), assumptions
)
@RealPredicate.register(log)
def _(expr, assumptions):
return ask(Q.positive(expr.args[0]), assumptions)
@RealPredicate.register_many(Determinant, MatrixElement, Trace)
def _(expr, assumptions):
return ask(Q.real_elements(expr.args[0]), assumptions)
# ExtendedRealPredicate
@ExtendedRealPredicate.register(object)
def _(expr, assumptions):
return ask(Q.negative_infinite(expr)
| Q.negative(expr)
| Q.zero(expr)
| Q.positive(expr)
| Q.positive_infinite(expr),
assumptions)
@ExtendedRealPredicate.register_many(Infinity, NegativeInfinity)
def _(expr, assumptions):
return True
@ExtendedRealPredicate.register_many(Add, Mul, Pow)
def _(expr, assumptions):
return test_closed_group(expr, assumptions, Q.extended_real)
# HermitianPredicate
@HermitianPredicate.register(object)
def _(expr, assumptions):
if isinstance(expr, MatrixBase):
return None
return ask(Q.real(expr), assumptions)
@HermitianPredicate.register(Add)
def _(expr, assumptions):
"""
* Hermitian + Hermitian -> Hermitian
* Hermitian + !Hermitian -> !Hermitian
"""
if expr.is_number:
raise MDNotImplementedError
return test_closed_group(expr, assumptions, Q.hermitian)
@HermitianPredicate.register(Mul)
def _(expr, assumptions):
"""
As long as there is at most only one noncommutative term:
* Hermitian*Hermitian -> Hermitian
* Hermitian*Antihermitian -> !Hermitian
* Antihermitian*Antihermitian -> Hermitian
"""
if expr.is_number:
raise MDNotImplementedError
nccount = 0
result = True
for arg in expr.args:
if ask(Q.antihermitian(arg), assumptions):
result = result ^ True
elif not ask(Q.hermitian(arg), assumptions):
break
if ask(~Q.commutative(arg), assumptions):
nccount += 1
if nccount > 1:
break
else:
return result
@HermitianPredicate.register(Pow)
def _(expr, assumptions):
"""
* Hermitian**Integer -> Hermitian
"""
if expr.is_number:
raise MDNotImplementedError
if expr.base == E:
if ask(Q.hermitian(expr.exp), assumptions):
return True
raise MDNotImplementedError
if ask(Q.hermitian(expr.base), assumptions):
if ask(Q.integer(expr.exp), assumptions):
return True
raise MDNotImplementedError
@HermitianPredicate.register_many(cos, sin)
def _(expr, assumptions):
if ask(Q.hermitian(expr.args[0]), assumptions):
return True
raise MDNotImplementedError
@HermitianPredicate.register(exp)
def _(expr, assumptions):
if ask(Q.hermitian(expr.exp), assumptions):
return True
raise MDNotImplementedError
@HermitianPredicate.register(MatrixBase)
def _(mat, assumptions):
rows, cols = mat.shape
ret_val = True
for i in range(rows):
for j in range(i, cols):
cond = fuzzy_bool(Eq(mat[i, j], conjugate(mat[j, i])))
if cond is None:
ret_val = None
if cond == False:
return False
if ret_val is None:
raise MDNotImplementedError
return ret_val
# ComplexPredicate
@ComplexPredicate.register_many(Abs, cos, exp, im, ImaginaryUnit, log, Number,
NumberSymbol, re, sin)
def _(expr, assumptions):
return True
@ComplexPredicate.register_many(Infinity, NegativeInfinity)
def _(expr, assumptions):
return False
@ComplexPredicate.register(Expr)
def _(expr, assumptions):
ret = expr.is_complex
if ret is None:
raise MDNotImplementedError
return ret
@ComplexPredicate.register_many(Add, Mul)
def _(expr, assumptions):
return test_closed_group(expr, assumptions, Q.complex)
@ComplexPredicate.register(Pow)
def _(expr, assumptions):
if expr.base == E:
return True
return test_closed_group(expr, assumptions, Q.complex)
@ComplexPredicate.register_many(Determinant, MatrixElement, Trace)
def _(expr, assumptions):
return ask(Q.complex_elements(expr.args[0]), assumptions)
@ComplexPredicate.register(NaN)
def _(expr, assumptions):
return None
# ImaginaryPredicate
def _Imaginary_number(expr, assumptions):
# let as_real_imag() work first since the expression may
# be simpler to evaluate
r = expr.as_real_imag()[0].evalf(2)
if r._prec != 1:
return not r
# allow None to be returned if we couldn't show for sure
# that r was 0
@ImaginaryPredicate.register(ImaginaryUnit)
def _(expr, assumptions):
return True
@ImaginaryPredicate.register(Expr)
def _(expr, assumptions):
ret = expr.is_imaginary
if ret is None:
raise MDNotImplementedError
return ret
@ImaginaryPredicate.register(Add)
def _(expr, assumptions):
"""
* Imaginary + Imaginary -> Imaginary
* Imaginary + Complex -> ?
* Imaginary + Real -> !Imaginary
"""
if expr.is_number:
return _Imaginary_number(expr, assumptions)
reals = 0
for arg in expr.args:
if ask(Q.imaginary(arg), assumptions):
pass
elif ask(Q.real(arg), assumptions):
reals += 1
else:
break
else:
if reals == 0:
return True
if reals == 1 or (len(expr.args) == reals):
# two reals could sum 0 thus giving an imaginary
return False
@ImaginaryPredicate.register(Mul)
def _(expr, assumptions):
"""
* Real*Imaginary -> Imaginary
* Imaginary*Imaginary -> Real
"""
if expr.is_number:
return _Imaginary_number(expr, assumptions)
result = False
reals = 0
for arg in expr.args:
if ask(Q.imaginary(arg), assumptions):
result = result ^ True
elif not ask(Q.real(arg), assumptions):
break
else:
if reals == len(expr.args):
return False
return result
@ImaginaryPredicate.register(Pow)
def _(expr, assumptions):
"""
* Imaginary**Odd -> Imaginary
* Imaginary**Even -> Real
* b**Imaginary -> !Imaginary if exponent is an integer
multiple of I*pi/log(b)
* Imaginary**Real -> ?
* Positive**Real -> Real
* Negative**Integer -> Real
* Negative**(Integer/2) -> Imaginary
* Negative**Real -> not Imaginary if exponent is not Rational
"""
if expr.is_number:
return _Imaginary_number(expr, assumptions)
if expr.base == E:
a = expr.exp/I/pi
return ask(Q.integer(2*a) & ~Q.integer(a), assumptions)
if expr.base.func == exp or (expr.base.is_Pow and expr.base.base == E):
if ask(Q.imaginary(expr.base.exp), assumptions):
if ask(Q.imaginary(expr.exp), assumptions):
return False
i = expr.base.exp/I/pi
if ask(Q.integer(2*i), assumptions):
return ask(Q.imaginary(((-1)**i)**expr.exp), assumptions)
if ask(Q.imaginary(expr.base), assumptions):
if ask(Q.integer(expr.exp), assumptions):
odd = ask(Q.odd(expr.exp), assumptions)
if odd is not None:
return odd
return
if ask(Q.imaginary(expr.exp), assumptions):
imlog = ask(Q.imaginary(log(expr.base)), assumptions)
if imlog is not None:
# I**i -> real; (2*I)**i -> complex ==> not imaginary
return False
if ask(Q.real(expr.base) & Q.real(expr.exp), assumptions):
if ask(Q.positive(expr.base), assumptions):
return False
else:
rat = ask(Q.rational(expr.exp), assumptions)
if not rat:
return rat
if ask(Q.integer(expr.exp), assumptions):
return False
else:
half = ask(Q.integer(2*expr.exp), assumptions)
if half:
return ask(Q.negative(expr.base), assumptions)
return half
@ImaginaryPredicate.register(log)
def _(expr, assumptions):
if ask(Q.real(expr.args[0]), assumptions):
if ask(Q.positive(expr.args[0]), assumptions):
return False
return
# XXX it should be enough to do
# return ask(Q.nonpositive(expr.args[0]), assumptions)
# but ask(Q.nonpositive(exp(x)), Q.imaginary(x)) -> None;
# it should return True since exp(x) will be either 0 or complex
if expr.args[0].func == exp or (expr.args[0].is_Pow and expr.args[0].base == E):
if expr.args[0].exp in [I, -I]:
return True
im = ask(Q.imaginary(expr.args[0]), assumptions)
if im is False:
return False
@ImaginaryPredicate.register(exp)
def _(expr, assumptions):
a = expr.exp/I/pi
return ask(Q.integer(2*a) & ~Q.integer(a), assumptions)
@ImaginaryPredicate.register_many(Number, NumberSymbol)
def _(expr, assumptions):
return not (expr.as_real_imag()[1] == 0)
@ImaginaryPredicate.register(NaN)
def _(expr, assumptions):
return None
# AntihermitianPredicate
@AntihermitianPredicate.register(object)
def _(expr, assumptions):
if isinstance(expr, MatrixBase):
return None
if ask(Q.zero(expr), assumptions):
return True
return ask(Q.imaginary(expr), assumptions)
@AntihermitianPredicate.register(Add)
def _(expr, assumptions):
"""
* Antihermitian + Antihermitian -> Antihermitian
* Antihermitian + !Antihermitian -> !Antihermitian
"""
if expr.is_number:
raise MDNotImplementedError
return test_closed_group(expr, assumptions, Q.antihermitian)
@AntihermitianPredicate.register(Mul)
def _(expr, assumptions):
"""
As long as there is at most only one noncommutative term:
* Hermitian*Hermitian -> !Antihermitian
* Hermitian*Antihermitian -> Antihermitian
* Antihermitian*Antihermitian -> !Antihermitian
"""
if expr.is_number:
raise MDNotImplementedError
nccount = 0
result = False
for arg in expr.args:
if ask(Q.antihermitian(arg), assumptions):
result = result ^ True
elif not ask(Q.hermitian(arg), assumptions):
break
if ask(~Q.commutative(arg), assumptions):
nccount += 1
if nccount > 1:
break
else:
return result
@AntihermitianPredicate.register(Pow)
def _(expr, assumptions):
"""
* Hermitian**Integer -> !Antihermitian
* Antihermitian**Even -> !Antihermitian
* Antihermitian**Odd -> Antihermitian
"""
if expr.is_number:
raise MDNotImplementedError
if ask(Q.hermitian(expr.base), assumptions):
if ask(Q.integer(expr.exp), assumptions):
return False
elif ask(Q.antihermitian(expr.base), assumptions):
if ask(Q.even(expr.exp), assumptions):
return False
elif ask(Q.odd(expr.exp), assumptions):
return True
raise MDNotImplementedError
@AntihermitianPredicate.register(MatrixBase)
def _(mat, assumptions):
rows, cols = mat.shape
ret_val = True
for i in range(rows):
for j in range(i, cols):
cond = fuzzy_bool(Eq(mat[i, j], -conjugate(mat[j, i])))
if cond is None:
ret_val = None
if cond == False:
return False
if ret_val is None:
raise MDNotImplementedError
return ret_val
# AlgebraicPredicate
@AlgebraicPredicate.register_many(AlgebraicNumber, Float, GoldenRatio,
ImaginaryUnit, TribonacciConstant)
def _(expr, assumptions):
return True
@AlgebraicPredicate.register_many(ComplexInfinity, Exp1, Infinity,
NegativeInfinity, Pi)
def _(expr, assumptions):
return False
@AlgebraicPredicate.register_many(Add, Mul)
def _(expr, assumptions):
return test_closed_group(expr, assumptions, Q.algebraic)
@AlgebraicPredicate.register(Pow)
def _(expr, assumptions):
if expr.base == E:
if ask(Q.algebraic(expr.exp), assumptions):
return ask(~Q.nonzero(expr.exp), assumptions)
return
return expr.exp.is_Rational and ask(Q.algebraic(expr.base), assumptions)
@AlgebraicPredicate.register(Rational)
def _(expr, assumptions):
return expr.q != 0
@AlgebraicPredicate.register_many(asin, atan, cos, sin, tan)
def _(expr, assumptions):
x = expr.args[0]
if ask(Q.algebraic(x), assumptions):
return ask(~Q.nonzero(x), assumptions)
@AlgebraicPredicate.register(exp)
def _(expr, assumptions):
x = expr.exp
if ask(Q.algebraic(x), assumptions):
return ask(~Q.nonzero(x), assumptions)
@AlgebraicPredicate.register_many(acot, cot)
def _(expr, assumptions):
x = expr.args[0]
if ask(Q.algebraic(x), assumptions):
return False
@AlgebraicPredicate.register_many(acos, log)
def _(expr, assumptions):
x = expr.args[0]
if ask(Q.algebraic(x), assumptions):
return ask(~Q.nonzero(x - 1), assumptions)
|
3f84234b8ae31e7d45cb498186d3d30b54537bce9bdeb56d1fd957a2e9486dc1 | """
This module implements some special functions that commonly appear in
combinatorial contexts (e.g. in power series); in particular,
sequences of rational numbers such as Bernoulli and Fibonacci numbers.
Factorials, binomial coefficients and related functions are located in
the separate 'factorials' module.
"""
from typing import Callable, Dict
from sympy.core import S, Symbol, Rational, Integer, Add, Dummy
from sympy.core.cache import cacheit
from sympy.core.compatibility import as_int, SYMPY_INTS
from sympy.core.function import Function, expand_mul
from sympy.core.logic import fuzzy_not
from sympy.core.numbers import E, pi
from sympy.core.relational import LessThan, StrictGreaterThan
from sympy.functions.combinatorial.factorials import binomial, factorial
from sympy.functions.elementary.exponential import log
from sympy.functions.elementary.integers import floor
from sympy.functions.elementary.miscellaneous import sqrt, cbrt
from sympy.functions.elementary.trigonometric import sin, cos, cot
from sympy.ntheory import isprime
from sympy.ntheory.primetest import is_square
from sympy.utilities.memoization import recurrence_memo
from mpmath import bernfrac, workprec
from mpmath.libmp import ifib as _ifib
def _product(a, b):
p = 1
for k in range(a, b + 1):
p *= k
return p
# Dummy symbol used for computing polynomial sequences
_sym = Symbol('x')
#----------------------------------------------------------------------------#
# #
# Carmichael numbers #
# #
#----------------------------------------------------------------------------#
class carmichael(Function):
"""
Carmichael Numbers:
Certain cryptographic algorithms make use of big prime numbers.
However, checking whether a big number is prime is not so easy.
Randomized prime number checking tests exist that offer a high degree of confidence of
accurate determination at low cost, such as the Fermat test.
Let 'a' be a random number between 2 and n - 1, where n is the number whose primality we are testing.
Then, n is probably prime if it satisfies the modular arithmetic congruence relation :
a^(n-1) = 1(mod n).
(where mod refers to the modulo operation)
If a number passes the Fermat test several times, then it is prime with a
high probability.
Unfortunately, certain composite numbers (non-primes) still pass the Fermat test
with every number smaller than themselves.
These numbers are called Carmichael numbers.
A Carmichael number will pass a Fermat primality test to every base b relatively prime to the number,
even though it is not actually prime. This makes tests based on Fermat's Little Theorem less effective than
strong probable prime tests such as the Baillie-PSW primality test and the Miller-Rabin primality test.
mr functions given in sympy/sympy/ntheory/primetest.py will produce wrong results for each and every
carmichael number.
Examples
========
>>> from sympy import carmichael
>>> carmichael.find_first_n_carmichaels(5)
[561, 1105, 1729, 2465, 2821]
>>> carmichael.is_prime(2465)
False
>>> carmichael.is_prime(1729)
False
>>> carmichael.find_carmichael_numbers_in_range(0, 562)
[561]
>>> carmichael.find_carmichael_numbers_in_range(0,1000)
[561]
>>> carmichael.find_carmichael_numbers_in_range(0,2000)
[561, 1105, 1729]
References
==========
.. [1] https://en.wikipedia.org/wiki/Carmichael_number
.. [2] https://en.wikipedia.org/wiki/Fermat_primality_test
.. [3] https://www.jstor.org/stable/23248683?seq=1#metadata_info_tab_contents
"""
@staticmethod
def is_perfect_square(n):
return is_square(n)
@staticmethod
def divides(p, n):
return n % p == 0
@staticmethod
def is_prime(n):
return isprime(n)
@staticmethod
def is_carmichael(n):
if n >= 0:
if (n == 1) or (carmichael.is_prime(n)) or (n % 2 == 0):
return False
divisors = list([1, n])
# get divisors
for i in range(3, n // 2 + 1, 2):
if n % i == 0:
divisors.append(i)
for i in divisors:
if carmichael.is_perfect_square(i) and i != 1:
return False
if carmichael.is_prime(i):
if not carmichael.divides(i - 1, n - 1):
return False
return True
else:
raise ValueError('The provided number must be greater than or equal to 0')
@staticmethod
def find_carmichael_numbers_in_range(x, y):
if 0 <= x <= y:
if x % 2 == 0:
return list([i for i in range(x + 1, y, 2) if carmichael.is_carmichael(i)])
else:
return list([i for i in range(x, y, 2) if carmichael.is_carmichael(i)])
else:
raise ValueError('The provided range is not valid. x and y must be non-negative integers and x <= y')
@staticmethod
def find_first_n_carmichaels(n):
i = 1
carmichaels = list()
while len(carmichaels) < n:
if carmichael.is_carmichael(i):
carmichaels.append(i)
i += 2
return carmichaels
#----------------------------------------------------------------------------#
# #
# Fibonacci numbers #
# #
#----------------------------------------------------------------------------#
class fibonacci(Function):
r"""
Fibonacci numbers / Fibonacci polynomials
The Fibonacci numbers are the integer sequence defined by the
initial terms `F_0 = 0`, `F_1 = 1` and the two-term recurrence
relation `F_n = F_{n-1} + F_{n-2}`. This definition
extended to arbitrary real and complex arguments using
the formula
.. math :: F_z = \frac{\phi^z - \cos(\pi z) \phi^{-z}}{\sqrt 5}
The Fibonacci polynomials are defined by `F_1(x) = 1`,
`F_2(x) = x`, and `F_n(x) = x*F_{n-1}(x) + F_{n-2}(x)` for `n > 2`.
For all positive integers `n`, `F_n(1) = F_n`.
* ``fibonacci(n)`` gives the `n^{th}` Fibonacci number, `F_n`
* ``fibonacci(n, x)`` gives the `n^{th}` Fibonacci polynomial in `x`, `F_n(x)`
Examples
========
>>> from sympy import fibonacci, Symbol
>>> [fibonacci(x) for x in range(11)]
[0, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55]
>>> fibonacci(5, Symbol('t'))
t**4 + 3*t**2 + 1
See Also
========
bell, bernoulli, catalan, euler, harmonic, lucas, genocchi, partition, tribonacci
References
==========
.. [1] https://en.wikipedia.org/wiki/Fibonacci_number
.. [2] http://mathworld.wolfram.com/FibonacciNumber.html
"""
@staticmethod
def _fib(n):
return _ifib(n)
@staticmethod
@recurrence_memo([None, S.One, _sym])
def _fibpoly(n, prev):
return (prev[-2] + _sym*prev[-1]).expand()
@classmethod
def eval(cls, n, sym=None):
if n is S.Infinity:
return S.Infinity
if n.is_Integer:
if sym is None:
n = int(n)
if n < 0:
return S.NegativeOne**(n + 1) * fibonacci(-n)
else:
return Integer(cls._fib(n))
else:
if n < 1:
raise ValueError("Fibonacci polynomials are defined "
"only for positive integer indices.")
return cls._fibpoly(n).subs(_sym, sym)
def _eval_rewrite_as_sqrt(self, n, **kwargs):
return 2**(-n)*sqrt(5)*((1 + sqrt(5))**n - (-sqrt(5) + 1)**n) / 5
def _eval_rewrite_as_GoldenRatio(self,n, **kwargs):
return (S.GoldenRatio**n - 1/(-S.GoldenRatio)**n)/(2*S.GoldenRatio-1)
#----------------------------------------------------------------------------#
# #
# Lucas numbers #
# #
#----------------------------------------------------------------------------#
class lucas(Function):
"""
Lucas numbers
Lucas numbers satisfy a recurrence relation similar to that of
the Fibonacci sequence, in which each term is the sum of the
preceding two. They are generated by choosing the initial
values `L_0 = 2` and `L_1 = 1`.
* ``lucas(n)`` gives the `n^{th}` Lucas number
Examples
========
>>> from sympy import lucas
>>> [lucas(x) for x in range(11)]
[2, 1, 3, 4, 7, 11, 18, 29, 47, 76, 123]
See Also
========
bell, bernoulli, catalan, euler, fibonacci, harmonic, genocchi, partition, tribonacci
References
==========
.. [1] https://en.wikipedia.org/wiki/Lucas_number
.. [2] http://mathworld.wolfram.com/LucasNumber.html
"""
@classmethod
def eval(cls, n):
if n is S.Infinity:
return S.Infinity
if n.is_Integer:
return fibonacci(n + 1) + fibonacci(n - 1)
def _eval_rewrite_as_sqrt(self, n, **kwargs):
return 2**(-n)*((1 + sqrt(5))**n + (-sqrt(5) + 1)**n)
#----------------------------------------------------------------------------#
# #
# Tribonacci numbers #
# #
#----------------------------------------------------------------------------#
class tribonacci(Function):
r"""
Tribonacci numbers / Tribonacci polynomials
The Tribonacci numbers are the integer sequence defined by the
initial terms `T_0 = 0`, `T_1 = 1`, `T_2 = 1` and the three-term
recurrence relation `T_n = T_{n-1} + T_{n-2} + T_{n-3}`.
The Tribonacci polynomials are defined by `T_0(x) = 0`, `T_1(x) = 1`,
`T_2(x) = x^2`, and `T_n(x) = x^2 T_{n-1}(x) + x T_{n-2}(x) + T_{n-3}(x)`
for `n > 2`. For all positive integers `n`, `T_n(1) = T_n`.
* ``tribonacci(n)`` gives the `n^{th}` Tribonacci number, `T_n`
* ``tribonacci(n, x)`` gives the `n^{th}` Tribonacci polynomial in `x`, `T_n(x)`
Examples
========
>>> from sympy import tribonacci, Symbol
>>> [tribonacci(x) for x in range(11)]
[0, 1, 1, 2, 4, 7, 13, 24, 44, 81, 149]
>>> tribonacci(5, Symbol('t'))
t**8 + 3*t**5 + 3*t**2
See Also
========
bell, bernoulli, catalan, euler, fibonacci, harmonic, lucas, genocchi, partition
References
==========
.. [1] https://en.wikipedia.org/wiki/Generalizations_of_Fibonacci_numbers#Tribonacci_numbers
.. [2] http://mathworld.wolfram.com/TribonacciNumber.html
.. [3] https://oeis.org/A000073
"""
@staticmethod
@recurrence_memo([S.Zero, S.One, S.One])
def _trib(n, prev):
return (prev[-3] + prev[-2] + prev[-1])
@staticmethod
@recurrence_memo([S.Zero, S.One, _sym**2])
def _tribpoly(n, prev):
return (prev[-3] + _sym*prev[-2] + _sym**2*prev[-1]).expand()
@classmethod
def eval(cls, n, sym=None):
if n is S.Infinity:
return S.Infinity
if n.is_Integer:
n = int(n)
if n < 0:
raise ValueError("Tribonacci polynomials are defined "
"only for non-negative integer indices.")
if sym is None:
return Integer(cls._trib(n))
else:
return cls._tribpoly(n).subs(_sym, sym)
def _eval_rewrite_as_sqrt(self, n, **kwargs):
w = (-1 + S.ImaginaryUnit * sqrt(3)) / 2
a = (1 + cbrt(19 + 3*sqrt(33)) + cbrt(19 - 3*sqrt(33))) / 3
b = (1 + w*cbrt(19 + 3*sqrt(33)) + w**2*cbrt(19 - 3*sqrt(33))) / 3
c = (1 + w**2*cbrt(19 + 3*sqrt(33)) + w*cbrt(19 - 3*sqrt(33))) / 3
Tn = (a**(n + 1)/((a - b)*(a - c))
+ b**(n + 1)/((b - a)*(b - c))
+ c**(n + 1)/((c - a)*(c - b)))
return Tn
def _eval_rewrite_as_TribonacciConstant(self, n, **kwargs):
b = cbrt(586 + 102*sqrt(33))
Tn = 3 * b * S.TribonacciConstant**n / (b**2 - 2*b + 4)
return floor(Tn + S.Half)
#----------------------------------------------------------------------------#
# #
# Bernoulli numbers #
# #
#----------------------------------------------------------------------------#
class bernoulli(Function):
r"""
Bernoulli numbers / Bernoulli polynomials
The Bernoulli numbers are a sequence of rational numbers
defined by `B_0 = 1` and the recursive relation (`n > 0`):
.. math :: 0 = \sum_{k=0}^n \binom{n+1}{k} B_k
They are also commonly defined by their exponential generating
function, which is `\frac{x}{e^x - 1}`. For odd indices > 1, the
Bernoulli numbers are zero.
The Bernoulli polynomials satisfy the analogous formula:
.. math :: B_n(x) = \sum_{k=0}^n \binom{n}{k} B_k x^{n-k}
Bernoulli numbers and Bernoulli polynomials are related as
`B_n(0) = B_n`.
We compute Bernoulli numbers using Ramanujan's formula:
.. math :: B_n = \frac{A(n) - S(n)}{\binom{n+3}{n}}
where:
.. math :: A(n) = \begin{cases} \frac{n+3}{3} &
n \equiv 0\ \text{or}\ 2 \pmod{6} \\
-\frac{n+3}{6} & n \equiv 4 \pmod{6} \end{cases}
and:
.. math :: S(n) = \sum_{k=1}^{[n/6]} \binom{n+3}{n-6k} B_{n-6k}
This formula is similar to the sum given in the definition, but
cuts 2/3 of the terms. For Bernoulli polynomials, we use the
formula in the definition.
* ``bernoulli(n)`` gives the nth Bernoulli number, `B_n`
* ``bernoulli(n, x)`` gives the nth Bernoulli polynomial in `x`, `B_n(x)`
Examples
========
>>> from sympy import bernoulli
>>> [bernoulli(n) for n in range(11)]
[1, -1/2, 1/6, 0, -1/30, 0, 1/42, 0, -1/30, 0, 5/66]
>>> bernoulli(1000001)
0
See Also
========
bell, catalan, euler, fibonacci, harmonic, lucas, genocchi, partition, tribonacci
References
==========
.. [1] https://en.wikipedia.org/wiki/Bernoulli_number
.. [2] https://en.wikipedia.org/wiki/Bernoulli_polynomial
.. [3] http://mathworld.wolfram.com/BernoulliNumber.html
.. [4] http://mathworld.wolfram.com/BernoulliPolynomial.html
"""
# Calculates B_n for positive even n
@staticmethod
def _calc_bernoulli(n):
s = 0
a = int(binomial(n + 3, n - 6))
for j in range(1, n//6 + 1):
s += a * bernoulli(n - 6*j)
# Avoid computing each binomial coefficient from scratch
a *= _product(n - 6 - 6*j + 1, n - 6*j)
a //= _product(6*j + 4, 6*j + 9)
if n % 6 == 4:
s = -Rational(n + 3, 6) - s
else:
s = Rational(n + 3, 3) - s
return s / binomial(n + 3, n)
# We implement a specialized memoization scheme to handle each
# case modulo 6 separately
_cache = {0: S.One, 2: Rational(1, 6), 4: Rational(-1, 30)}
_highest = {0: 0, 2: 2, 4: 4}
@classmethod
def eval(cls, n, sym=None):
if n.is_Number:
if n.is_Integer and n.is_nonnegative:
if n.is_zero:
return S.One
elif n is S.One:
if sym is None:
return Rational(-1, 2)
else:
return sym - S.Half
# Bernoulli numbers
elif sym is None:
if n.is_odd:
return S.Zero
n = int(n)
# Use mpmath for enormous Bernoulli numbers
if n > 500:
p, q = bernfrac(n)
return Rational(int(p), int(q))
case = n % 6
highest_cached = cls._highest[case]
if n <= highest_cached:
return cls._cache[n]
# To avoid excessive recursion when, say, bernoulli(1000) is
# requested, calculate and cache the entire sequence ... B_988,
# B_994, B_1000 in increasing order
for i in range(highest_cached + 6, n + 6, 6):
b = cls._calc_bernoulli(i)
cls._cache[i] = b
cls._highest[case] = i
return b
# Bernoulli polynomials
else:
n, result = int(n), []
for k in range(n + 1):
result.append(binomial(n, k)*cls(k)*sym**(n - k))
return Add(*result)
else:
raise ValueError("Bernoulli numbers are defined only"
" for nonnegative integer indices.")
if sym is None:
if n.is_odd and (n - 1).is_positive:
return S.Zero
#----------------------------------------------------------------------------#
# #
# Bell numbers #
# #
#----------------------------------------------------------------------------#
class bell(Function):
r"""
Bell numbers / Bell polynomials
The Bell numbers satisfy `B_0 = 1` and
.. math:: B_n = \sum_{k=0}^{n-1} \binom{n-1}{k} B_k.
They are also given by:
.. math:: B_n = \frac{1}{e} \sum_{k=0}^{\infty} \frac{k^n}{k!}.
The Bell polynomials are given by `B_0(x) = 1` and
.. math:: B_n(x) = x \sum_{k=1}^{n-1} \binom{n-1}{k-1} B_{k-1}(x).
The second kind of Bell polynomials (are sometimes called "partial" Bell
polynomials or incomplete Bell polynomials) are defined as
.. math:: B_{n,k}(x_1, x_2,\dotsc x_{n-k+1}) =
\sum_{j_1+j_2+j_2+\dotsb=k \atop j_1+2j_2+3j_2+\dotsb=n}
\frac{n!}{j_1!j_2!\dotsb j_{n-k+1}!}
\left(\frac{x_1}{1!} \right)^{j_1}
\left(\frac{x_2}{2!} \right)^{j_2} \dotsb
\left(\frac{x_{n-k+1}}{(n-k+1)!} \right) ^{j_{n-k+1}}.
* ``bell(n)`` gives the `n^{th}` Bell number, `B_n`.
* ``bell(n, x)`` gives the `n^{th}` Bell polynomial, `B_n(x)`.
* ``bell(n, k, (x1, x2, ...))`` gives Bell polynomials of the second kind,
`B_{n,k}(x_1, x_2, \dotsc, x_{n-k+1})`.
Notes
=====
Not to be confused with Bernoulli numbers and Bernoulli polynomials,
which use the same notation.
Examples
========
>>> from sympy import bell, Symbol, symbols
>>> [bell(n) for n in range(11)]
[1, 1, 2, 5, 15, 52, 203, 877, 4140, 21147, 115975]
>>> bell(30)
846749014511809332450147
>>> bell(4, Symbol('t'))
t**4 + 6*t**3 + 7*t**2 + t
>>> bell(6, 2, symbols('x:6')[1:])
6*x1*x5 + 15*x2*x4 + 10*x3**2
See Also
========
bernoulli, catalan, euler, fibonacci, harmonic, lucas, genocchi, partition, tribonacci
References
==========
.. [1] https://en.wikipedia.org/wiki/Bell_number
.. [2] http://mathworld.wolfram.com/BellNumber.html
.. [3] http://mathworld.wolfram.com/BellPolynomial.html
"""
@staticmethod
@recurrence_memo([1, 1])
def _bell(n, prev):
s = 1
a = 1
for k in range(1, n):
a = a * (n - k) // k
s += a * prev[k]
return s
@staticmethod
@recurrence_memo([S.One, _sym])
def _bell_poly(n, prev):
s = 1
a = 1
for k in range(2, n + 1):
a = a * (n - k + 1) // (k - 1)
s += a * prev[k - 1]
return expand_mul(_sym * s)
@staticmethod
def _bell_incomplete_poly(n, k, symbols):
r"""
The second kind of Bell polynomials (incomplete Bell polynomials).
Calculated by recurrence formula:
.. math:: B_{n,k}(x_1, x_2, \dotsc, x_{n-k+1}) =
\sum_{m=1}^{n-k+1}
\x_m \binom{n-1}{m-1} B_{n-m,k-1}(x_1, x_2, \dotsc, x_{n-m-k})
where
`B_{0,0} = 1;`
`B_{n,0} = 0; for n \ge 1`
`B_{0,k} = 0; for k \ge 1`
"""
if (n == 0) and (k == 0):
return S.One
elif (n == 0) or (k == 0):
return S.Zero
s = S.Zero
a = S.One
for m in range(1, n - k + 2):
s += a * bell._bell_incomplete_poly(
n - m, k - 1, symbols) * symbols[m - 1]
a = a * (n - m) / m
return expand_mul(s)
@classmethod
def eval(cls, n, k_sym=None, symbols=None):
if n is S.Infinity:
if k_sym is None:
return S.Infinity
else:
raise ValueError("Bell polynomial is not defined")
if n.is_negative or n.is_integer is False:
raise ValueError("a non-negative integer expected")
if n.is_Integer and n.is_nonnegative:
if k_sym is None:
return Integer(cls._bell(int(n)))
elif symbols is None:
return cls._bell_poly(int(n)).subs(_sym, k_sym)
else:
r = cls._bell_incomplete_poly(int(n), int(k_sym), symbols)
return r
def _eval_rewrite_as_Sum(self, n, k_sym=None, symbols=None, **kwargs):
from sympy import Sum
if (k_sym is not None) or (symbols is not None):
return self
# Dobinski's formula
if not n.is_nonnegative:
return self
k = Dummy('k', integer=True, nonnegative=True)
return 1 / E * Sum(k**n / factorial(k), (k, 0, S.Infinity))
#----------------------------------------------------------------------------#
# #
# Harmonic numbers #
# #
#----------------------------------------------------------------------------#
class harmonic(Function):
r"""
Harmonic numbers
The nth harmonic number is given by `\operatorname{H}_{n} =
1 + \frac{1}{2} + \frac{1}{3} + \ldots + \frac{1}{n}`.
More generally:
.. math:: \operatorname{H}_{n,m} = \sum_{k=1}^{n} \frac{1}{k^m}
As `n \rightarrow \infty`, `\operatorname{H}_{n,m} \rightarrow \zeta(m)`,
the Riemann zeta function.
* ``harmonic(n)`` gives the nth harmonic number, `\operatorname{H}_n`
* ``harmonic(n, m)`` gives the nth generalized harmonic number
of order `m`, `\operatorname{H}_{n,m}`, where
``harmonic(n) == harmonic(n, 1)``
Examples
========
>>> from sympy import harmonic, oo
>>> [harmonic(n) for n in range(6)]
[0, 1, 3/2, 11/6, 25/12, 137/60]
>>> [harmonic(n, 2) for n in range(6)]
[0, 1, 5/4, 49/36, 205/144, 5269/3600]
>>> harmonic(oo, 2)
pi**2/6
>>> from sympy import Symbol, Sum
>>> n = Symbol("n")
>>> harmonic(n).rewrite(Sum)
Sum(1/_k, (_k, 1, n))
We can evaluate harmonic numbers for all integral and positive
rational arguments:
>>> from sympy import S, expand_func, simplify
>>> harmonic(8)
761/280
>>> harmonic(11)
83711/27720
>>> H = harmonic(1/S(3))
>>> H
harmonic(1/3)
>>> He = expand_func(H)
>>> He
-log(6) - sqrt(3)*pi/6 + 2*Sum(log(sin(_k*pi/3))*cos(2*_k*pi/3), (_k, 1, 1))
+ 3*Sum(1/(3*_k + 1), (_k, 0, 0))
>>> He.doit()
-log(6) - sqrt(3)*pi/6 - log(sqrt(3)/2) + 3
>>> H = harmonic(25/S(7))
>>> He = simplify(expand_func(H).doit())
>>> He
log(sin(2*pi/7)**(2*cos(16*pi/7))/(14*sin(pi/7)**(2*cos(pi/7))*cos(pi/14)**(2*sin(pi/14)))) + pi*tan(pi/14)/2 + 30247/9900
>>> He.n(40)
1.983697455232980674869851942390639915940
>>> harmonic(25/S(7)).n(40)
1.983697455232980674869851942390639915940
We can rewrite harmonic numbers in terms of polygamma functions:
>>> from sympy import digamma, polygamma
>>> m = Symbol("m")
>>> harmonic(n).rewrite(digamma)
polygamma(0, n + 1) + EulerGamma
>>> harmonic(n).rewrite(polygamma)
polygamma(0, n + 1) + EulerGamma
>>> harmonic(n,3).rewrite(polygamma)
polygamma(2, n + 1)/2 - polygamma(2, 1)/2
>>> harmonic(n,m).rewrite(polygamma)
(-1)**m*(polygamma(m - 1, 1) - polygamma(m - 1, n + 1))/factorial(m - 1)
Integer offsets in the argument can be pulled out:
>>> from sympy import expand_func
>>> expand_func(harmonic(n+4))
harmonic(n) + 1/(n + 4) + 1/(n + 3) + 1/(n + 2) + 1/(n + 1)
>>> expand_func(harmonic(n-4))
harmonic(n) - 1/(n - 1) - 1/(n - 2) - 1/(n - 3) - 1/n
Some limits can be computed as well:
>>> from sympy import limit, oo
>>> limit(harmonic(n), n, oo)
oo
>>> limit(harmonic(n, 2), n, oo)
pi**2/6
>>> limit(harmonic(n, 3), n, oo)
-polygamma(2, 1)/2
However we can not compute the general relation yet:
>>> limit(harmonic(n, m), n, oo)
harmonic(oo, m)
which equals ``zeta(m)`` for ``m > 1``.
See Also
========
bell, bernoulli, catalan, euler, fibonacci, lucas, genocchi, partition, tribonacci
References
==========
.. [1] https://en.wikipedia.org/wiki/Harmonic_number
.. [2] http://functions.wolfram.com/GammaBetaErf/HarmonicNumber/
.. [3] http://functions.wolfram.com/GammaBetaErf/HarmonicNumber2/
"""
# Generate one memoized Harmonic number-generating function for each
# order and store it in a dictionary
_functions = {} # type: Dict[Integer, Callable[[int], Rational]]
@classmethod
def eval(cls, n, m=None):
from sympy import zeta
if m is S.One:
return cls(n)
if m is None:
m = S.One
if m.is_zero:
return n
if n is S.Infinity and m.is_Number:
# TODO: Fix for symbolic values of m
if m.is_negative:
return S.NaN
elif LessThan(m, S.One):
return S.Infinity
elif StrictGreaterThan(m, S.One):
return zeta(m)
else:
return cls
if n == 0:
return S.Zero
if n.is_Integer and n.is_nonnegative and m.is_Integer:
if not m in cls._functions:
@recurrence_memo([0])
def f(n, prev):
return prev[-1] + S.One / n**m
cls._functions[m] = f
return cls._functions[m](int(n))
def _eval_rewrite_as_polygamma(self, n, m=1, **kwargs):
from sympy.functions.special.gamma_functions import polygamma
return S.NegativeOne**m/factorial(m - 1) * (polygamma(m - 1, 1) - polygamma(m - 1, n + 1))
def _eval_rewrite_as_digamma(self, n, m=1, **kwargs):
from sympy.functions.special.gamma_functions import polygamma
return self.rewrite(polygamma)
def _eval_rewrite_as_trigamma(self, n, m=1, **kwargs):
from sympy.functions.special.gamma_functions import polygamma
return self.rewrite(polygamma)
def _eval_rewrite_as_Sum(self, n, m=None, **kwargs):
from sympy import Sum
k = Dummy("k", integer=True)
if m is None:
m = S.One
return Sum(k**(-m), (k, 1, n))
def _eval_expand_func(self, **hints):
from sympy import Sum
n = self.args[0]
m = self.args[1] if len(self.args) == 2 else 1
if m == S.One:
if n.is_Add:
off = n.args[0]
nnew = n - off
if off.is_Integer and off.is_positive:
result = [S.One/(nnew + i) for i in range(off, 0, -1)] + [harmonic(nnew)]
return Add(*result)
elif off.is_Integer and off.is_negative:
result = [-S.One/(nnew + i) for i in range(0, off, -1)] + [harmonic(nnew)]
return Add(*result)
if n.is_Rational:
# Expansions for harmonic numbers at general rational arguments (u + p/q)
# Split n as u + p/q with p < q
p, q = n.as_numer_denom()
u = p // q
p = p - u * q
if u.is_nonnegative and p.is_positive and q.is_positive and p < q:
k = Dummy("k")
t1 = q * Sum(1 / (q * k + p), (k, 0, u))
t2 = 2 * Sum(cos((2 * pi * p * k) / S(q)) *
log(sin((pi * k) / S(q))),
(k, 1, floor((q - 1) / S(2))))
t3 = (pi / 2) * cot((pi * p) / q) + log(2 * q)
return t1 + t2 - t3
return self
def _eval_rewrite_as_tractable(self, n, m=1, limitvar=None, **kwargs):
from sympy import polygamma
return self.rewrite(polygamma).rewrite("tractable", deep=True)
def _eval_evalf(self, prec):
from sympy import polygamma
if all(i.is_number for i in self.args):
return self.rewrite(polygamma)._eval_evalf(prec)
#----------------------------------------------------------------------------#
# #
# Euler numbers #
# #
#----------------------------------------------------------------------------#
class euler(Function):
r"""
Euler numbers / Euler polynomials
The Euler numbers are given by:
.. math:: E_{2n} = I \sum_{k=1}^{2n+1} \sum_{j=0}^k \binom{k}{j}
\frac{(-1)^j (k-2j)^{2n+1}}{2^k I^k k}
.. math:: E_{2n+1} = 0
Euler numbers and Euler polynomials are related by
.. math:: E_n = 2^n E_n\left(\frac{1}{2}\right).
We compute symbolic Euler polynomials using [5]_
.. math:: E_n(x) = \sum_{k=0}^n \binom{n}{k} \frac{E_k}{2^k}
\left(x - \frac{1}{2}\right)^{n-k}.
However, numerical evaluation of the Euler polynomial is computed
more efficiently (and more accurately) using the mpmath library.
* ``euler(n)`` gives the `n^{th}` Euler number, `E_n`.
* ``euler(n, x)`` gives the `n^{th}` Euler polynomial, `E_n(x)`.
Examples
========
>>> from sympy import Symbol, S
>>> from sympy.functions import euler
>>> [euler(n) for n in range(10)]
[1, 0, -1, 0, 5, 0, -61, 0, 1385, 0]
>>> n = Symbol("n")
>>> euler(n + 2*n)
euler(3*n)
>>> x = Symbol("x")
>>> euler(n, x)
euler(n, x)
>>> euler(0, x)
1
>>> euler(1, x)
x - 1/2
>>> euler(2, x)
x**2 - x
>>> euler(3, x)
x**3 - 3*x**2/2 + 1/4
>>> euler(4, x)
x**4 - 2*x**3 + x
>>> euler(12, S.Half)
2702765/4096
>>> euler(12)
2702765
See Also
========
bell, bernoulli, catalan, fibonacci, harmonic, lucas, genocchi, partition, tribonacci
References
==========
.. [1] https://en.wikipedia.org/wiki/Euler_numbers
.. [2] http://mathworld.wolfram.com/EulerNumber.html
.. [3] https://en.wikipedia.org/wiki/Alternating_permutation
.. [4] http://mathworld.wolfram.com/AlternatingPermutation.html
.. [5] http://dlmf.nist.gov/24.2#ii
"""
@classmethod
def eval(cls, m, sym=None):
if m.is_Number:
if m.is_Integer and m.is_nonnegative:
# Euler numbers
if sym is None:
if m.is_odd:
return S.Zero
from mpmath import mp
m = m._to_mpmath(mp.prec)
res = mp.eulernum(m, exact=True)
return Integer(res)
# Euler polynomial
else:
from sympy.core.evalf import pure_complex
reim = pure_complex(sym, or_real=True)
# Evaluate polynomial numerically using mpmath
if reim and all(a.is_Float or a.is_Integer for a in reim) \
and any(a.is_Float for a in reim):
from mpmath import mp
from sympy import Expr
m = int(m)
# XXX ComplexFloat (#12192) would be nice here, above
prec = min([a._prec for a in reim if a.is_Float])
with workprec(prec):
res = mp.eulerpoly(m, sym)
return Expr._from_mpmath(res, prec)
# Construct polynomial symbolically from definition
m, result = int(m), []
for k in range(m + 1):
result.append(binomial(m, k)*cls(k)/(2**k)*(sym - S.Half)**(m - k))
return Add(*result).expand()
else:
raise ValueError("Euler numbers are defined only"
" for nonnegative integer indices.")
if sym is None:
if m.is_odd and m.is_positive:
return S.Zero
def _eval_rewrite_as_Sum(self, n, x=None, **kwargs):
from sympy import Sum
if x is None and n.is_even:
k = Dummy("k", integer=True)
j = Dummy("j", integer=True)
n = n / 2
Em = (S.ImaginaryUnit * Sum(Sum(binomial(k, j) * ((-1)**j * (k - 2*j)**(2*n + 1)) /
(2**k*S.ImaginaryUnit**k * k), (j, 0, k)), (k, 1, 2*n + 1)))
return Em
if x:
k = Dummy("k", integer=True)
return Sum(binomial(n, k)*euler(k)/2**k*(x - S.Half)**(n - k), (k, 0, n))
def _eval_evalf(self, prec):
m, x = (self.args[0], None) if len(self.args) == 1 else self.args
if x is None and m.is_Integer and m.is_nonnegative:
from mpmath import mp
from sympy import Expr
m = m._to_mpmath(prec)
with workprec(prec):
res = mp.eulernum(m)
return Expr._from_mpmath(res, prec)
if x and x.is_number and m.is_Integer and m.is_nonnegative:
from mpmath import mp
from sympy import Expr
m = int(m)
x = x._to_mpmath(prec)
with workprec(prec):
res = mp.eulerpoly(m, x)
return Expr._from_mpmath(res, prec)
#----------------------------------------------------------------------------#
# #
# Catalan numbers #
# #
#----------------------------------------------------------------------------#
class catalan(Function):
r"""
Catalan numbers
The `n^{th}` catalan number is given by:
.. math :: C_n = \frac{1}{n+1} \binom{2n}{n}
* ``catalan(n)`` gives the `n^{th}` Catalan number, `C_n`
Examples
========
>>> from sympy import (Symbol, binomial, gamma, hyper, catalan,
... diff, combsimp, Rational, I)
>>> [catalan(i) for i in range(1,10)]
[1, 2, 5, 14, 42, 132, 429, 1430, 4862]
>>> n = Symbol("n", integer=True)
>>> catalan(n)
catalan(n)
Catalan numbers can be transformed into several other, identical
expressions involving other mathematical functions
>>> catalan(n).rewrite(binomial)
binomial(2*n, n)/(n + 1)
>>> catalan(n).rewrite(gamma)
4**n*gamma(n + 1/2)/(sqrt(pi)*gamma(n + 2))
>>> catalan(n).rewrite(hyper)
hyper((1 - n, -n), (2,), 1)
For some non-integer values of n we can get closed form
expressions by rewriting in terms of gamma functions:
>>> catalan(Rational(1, 2)).rewrite(gamma)
8/(3*pi)
We can differentiate the Catalan numbers C(n) interpreted as a
continuous real function in n:
>>> diff(catalan(n), n)
(polygamma(0, n + 1/2) - polygamma(0, n + 2) + log(4))*catalan(n)
As a more advanced example consider the following ratio
between consecutive numbers:
>>> combsimp((catalan(n + 1)/catalan(n)).rewrite(binomial))
2*(2*n + 1)/(n + 2)
The Catalan numbers can be generalized to complex numbers:
>>> catalan(I).rewrite(gamma)
4**I*gamma(1/2 + I)/(sqrt(pi)*gamma(2 + I))
and evaluated with arbitrary precision:
>>> catalan(I).evalf(20)
0.39764993382373624267 - 0.020884341620842555705*I
See Also
========
bell, bernoulli, euler, fibonacci, harmonic, lucas, genocchi, partition, tribonacci
sympy.functions.combinatorial.factorials.binomial
References
==========
.. [1] https://en.wikipedia.org/wiki/Catalan_number
.. [2] http://mathworld.wolfram.com/CatalanNumber.html
.. [3] http://functions.wolfram.com/GammaBetaErf/CatalanNumber/
.. [4] http://geometer.org/mathcircles/catalan.pdf
"""
@classmethod
def eval(cls, n):
from sympy import gamma
if (n.is_Integer and n.is_nonnegative) or \
(n.is_noninteger and n.is_negative):
return 4**n*gamma(n + S.Half)/(gamma(S.Half)*gamma(n + 2))
if (n.is_integer and n.is_negative):
if (n + 1).is_negative:
return S.Zero
if (n + 1).is_zero:
return Rational(-1, 2)
def fdiff(self, argindex=1):
from sympy import polygamma, log
n = self.args[0]
return catalan(n)*(polygamma(0, n + S.Half) - polygamma(0, n + 2) + log(4))
def _eval_rewrite_as_binomial(self, n, **kwargs):
return binomial(2*n, n)/(n + 1)
def _eval_rewrite_as_factorial(self, n, **kwargs):
return factorial(2*n) / (factorial(n+1) * factorial(n))
def _eval_rewrite_as_gamma(self, n, piecewise=True, **kwargs):
from sympy import gamma
# The gamma function allows to generalize Catalan numbers to complex n
return 4**n*gamma(n + S.Half)/(gamma(S.Half)*gamma(n + 2))
def _eval_rewrite_as_hyper(self, n, **kwargs):
from sympy import hyper
return hyper([1 - n, -n], [2], 1)
def _eval_rewrite_as_Product(self, n, **kwargs):
from sympy import Product
if not (n.is_integer and n.is_nonnegative):
return self
k = Dummy('k', integer=True, positive=True)
return Product((n + k) / k, (k, 2, n))
def _eval_is_integer(self):
if self.args[0].is_integer and self.args[0].is_nonnegative:
return True
def _eval_is_positive(self):
if self.args[0].is_nonnegative:
return True
def _eval_is_composite(self):
if self.args[0].is_integer and (self.args[0] - 3).is_positive:
return True
def _eval_evalf(self, prec):
from sympy import gamma
if self.args[0].is_number:
return self.rewrite(gamma)._eval_evalf(prec)
#----------------------------------------------------------------------------#
# #
# Genocchi numbers #
# #
#----------------------------------------------------------------------------#
class genocchi(Function):
r"""
Genocchi numbers
The Genocchi numbers are a sequence of integers `G_n` that satisfy the
relation:
.. math:: \frac{2t}{e^t + 1} = \sum_{n=1}^\infty \frac{G_n t^n}{n!}
Examples
========
>>> from sympy import Symbol
>>> from sympy.functions import genocchi
>>> [genocchi(n) for n in range(1, 9)]
[1, -1, 0, 1, 0, -3, 0, 17]
>>> n = Symbol('n', integer=True, positive=True)
>>> genocchi(2*n + 1)
0
See Also
========
bell, bernoulli, catalan, euler, fibonacci, harmonic, lucas, partition, tribonacci
References
==========
.. [1] https://en.wikipedia.org/wiki/Genocchi_number
.. [2] http://mathworld.wolfram.com/GenocchiNumber.html
"""
@classmethod
def eval(cls, n):
if n.is_Number:
if (not n.is_Integer) or n.is_nonpositive:
raise ValueError("Genocchi numbers are defined only for " +
"positive integers")
return 2 * (1 - S(2) ** n) * bernoulli(n)
if n.is_odd and (n - 1).is_positive:
return S.Zero
if (n - 1).is_zero:
return S.One
def _eval_rewrite_as_bernoulli(self, n, **kwargs):
if n.is_integer and n.is_nonnegative:
return (1 - S(2) ** n) * bernoulli(n) * 2
def _eval_is_integer(self):
if self.args[0].is_integer and self.args[0].is_positive:
return True
def _eval_is_negative(self):
n = self.args[0]
if n.is_integer and n.is_positive:
if n.is_odd:
return False
return (n / 2).is_odd
def _eval_is_positive(self):
n = self.args[0]
if n.is_integer and n.is_positive:
if n.is_odd:
return fuzzy_not((n - 1).is_positive)
return (n / 2).is_even
def _eval_is_even(self):
n = self.args[0]
if n.is_integer and n.is_positive:
if n.is_even:
return False
return (n - 1).is_positive
def _eval_is_odd(self):
n = self.args[0]
if n.is_integer and n.is_positive:
if n.is_even:
return True
return fuzzy_not((n - 1).is_positive)
def _eval_is_prime(self):
n = self.args[0]
# only G_6 = -3 and G_8 = 17 are prime,
# but SymPy does not consider negatives as prime
# so only n=8 is tested
return (n - 8).is_zero
#----------------------------------------------------------------------------#
# #
# Partition numbers #
# #
#----------------------------------------------------------------------------#
_npartition = [1, 1]
class partition(Function):
r"""
Partition numbers
The Partition numbers are a sequence of integers `p_n` that represent the
number of distinct ways of representing `n` as a sum of natural numbers
(with order irrelevant). The generating function for `p_n` is given by:
.. math:: \sum_{n=0}^\infty p_n x^n = \prod_{k=1}^\infty (1 - x^k)^{-1}
Examples
========
>>> from sympy import Symbol
>>> from sympy.functions import partition
>>> [partition(n) for n in range(9)]
[1, 1, 2, 3, 5, 7, 11, 15, 22]
>>> n = Symbol('n', integer=True, negative=True)
>>> partition(n)
0
See Also
========
bell, bernoulli, catalan, euler, fibonacci, harmonic, lucas, genocchi, tribonacci
References
==========
.. [1] https://en.wikipedia.org/wiki/Partition_(number_theory%29
.. [2] https://en.wikipedia.org/wiki/Pentagonal_number_theorem
"""
@staticmethod
def _partition(n):
L = len(_npartition)
if n < L:
return _npartition[n]
# lengthen cache
for _n in range(L, n + 1):
v, p, i = 0, 0, 0
while 1:
s = 0
p += 3*i + 1 # p = pentagonal number: 1, 5, 12, ...
if _n >= p:
s += _npartition[_n - p]
i += 1
gp = p + i # gp = generalized pentagonal: 2, 7, 15, ...
if _n >= gp:
s += _npartition[_n - gp]
if s == 0:
break
else:
v += s if i%2 == 1 else -s
_npartition.append(v)
return v
@classmethod
def eval(cls, n):
is_int = n.is_integer
if is_int == False:
raise ValueError("Partition numbers are defined only for "
"integers")
elif is_int:
if n.is_negative:
return S.Zero
if n.is_zero or (n - 1).is_zero:
return S.One
if n.is_Integer:
return Integer(cls._partition(n))
def _eval_is_integer(self):
if self.args[0].is_integer:
return True
def _eval_is_negative(self):
if self.args[0].is_integer:
return False
def _eval_is_positive(self):
n = self.args[0]
if n.is_nonnegative and n.is_integer:
return True
#######################################################################
###
### Functions for enumerating partitions, permutations and combinations
###
#######################################################################
class _MultisetHistogram(tuple):
pass
_N = -1
_ITEMS = -2
_M = slice(None, _ITEMS)
def _multiset_histogram(n):
"""Return tuple used in permutation and combination counting. Input
is a dictionary giving items with counts as values or a sequence of
items (which need not be sorted).
The data is stored in a class deriving from tuple so it is easily
recognized and so it can be converted easily to a list.
"""
if isinstance(n, dict): # item: count
if not all(isinstance(v, int) and v >= 0 for v in n.values()):
raise ValueError
tot = sum(n.values())
items = sum(1 for k in n if n[k] > 0)
return _MultisetHistogram([n[k] for k in n if n[k] > 0] + [items, tot])
else:
n = list(n)
s = set(n)
if len(s) == len(n):
n = [1]*len(n)
n.extend([len(n), len(n)])
return _MultisetHistogram(n)
m = dict(zip(s, range(len(s))))
d = dict(zip(range(len(s)), [0]*len(s)))
for i in n:
d[m[i]] += 1
return _multiset_histogram(d)
def nP(n, k=None, replacement=False):
"""Return the number of permutations of ``n`` items taken ``k`` at a time.
Possible values for ``n``:
integer - set of length ``n``
sequence - converted to a multiset internally
multiset - {element: multiplicity}
If ``k`` is None then the total of all permutations of length 0
through the number of items represented by ``n`` will be returned.
If ``replacement`` is True then a given item can appear more than once
in the ``k`` items. (For example, for 'ab' permutations of 2 would
include 'aa', 'ab', 'ba' and 'bb'.) The multiplicity of elements in
``n`` is ignored when ``replacement`` is True but the total number
of elements is considered since no element can appear more times than
the number of elements in ``n``.
Examples
========
>>> from sympy.functions.combinatorial.numbers import nP
>>> from sympy.utilities.iterables import multiset_permutations, multiset
>>> nP(3, 2)
6
>>> nP('abc', 2) == nP(multiset('abc'), 2) == 6
True
>>> nP('aab', 2)
3
>>> nP([1, 2, 2], 2)
3
>>> [nP(3, i) for i in range(4)]
[1, 3, 6, 6]
>>> nP(3) == sum(_)
True
When ``replacement`` is True, each item can have multiplicity
equal to the length represented by ``n``:
>>> nP('aabc', replacement=True)
121
>>> [len(list(multiset_permutations('aaaabbbbcccc', i))) for i in range(5)]
[1, 3, 9, 27, 81]
>>> sum(_)
121
See Also
========
sympy.utilities.iterables.multiset_permutations
References
==========
.. [1] https://en.wikipedia.org/wiki/Permutation
"""
try:
n = as_int(n)
except ValueError:
return Integer(_nP(_multiset_histogram(n), k, replacement))
return Integer(_nP(n, k, replacement))
@cacheit
def _nP(n, k=None, replacement=False):
from sympy.functions.combinatorial.factorials import factorial
from sympy.core.mul import prod
if k == 0:
return 1
if isinstance(n, SYMPY_INTS): # n different items
# assert n >= 0
if k is None:
return sum(_nP(n, i, replacement) for i in range(n + 1))
elif replacement:
return n**k
elif k > n:
return 0
elif k == n:
return factorial(k)
elif k == 1:
return n
else:
# assert k >= 0
return _product(n - k + 1, n)
elif isinstance(n, _MultisetHistogram):
if k is None:
return sum(_nP(n, i, replacement) for i in range(n[_N] + 1))
elif replacement:
return n[_ITEMS]**k
elif k == n[_N]:
return factorial(k)/prod([factorial(i) for i in n[_M] if i > 1])
elif k > n[_N]:
return 0
elif k == 1:
return n[_ITEMS]
else:
# assert k >= 0
tot = 0
n = list(n)
for i in range(len(n[_M])):
if not n[i]:
continue
n[_N] -= 1
if n[i] == 1:
n[i] = 0
n[_ITEMS] -= 1
tot += _nP(_MultisetHistogram(n), k - 1)
n[_ITEMS] += 1
n[i] = 1
else:
n[i] -= 1
tot += _nP(_MultisetHistogram(n), k - 1)
n[i] += 1
n[_N] += 1
return tot
@cacheit
def _AOP_product(n):
"""for n = (m1, m2, .., mk) return the coefficients of the polynomial,
prod(sum(x**i for i in range(nj + 1)) for nj in n); i.e. the coefficients
of the product of AOPs (all-one polynomials) or order given in n. The
resulting coefficient corresponding to x**r is the number of r-length
combinations of sum(n) elements with multiplicities given in n.
The coefficients are given as a default dictionary (so if a query is made
for a key that is not present, 0 will be returned).
Examples
========
>>> from sympy.functions.combinatorial.numbers import _AOP_product
>>> from sympy.abc import x
>>> n = (2, 2, 3) # e.g. aabbccc
>>> prod = ((x**2 + x + 1)*(x**2 + x + 1)*(x**3 + x**2 + x + 1)).expand()
>>> c = _AOP_product(n); dict(c)
{0: 1, 1: 3, 2: 6, 3: 8, 4: 8, 5: 6, 6: 3, 7: 1}
>>> [c[i] for i in range(8)] == [prod.coeff(x, i) for i in range(8)]
True
The generating poly used here is the same as that listed in
http://tinyurl.com/cep849r, but in a refactored form.
"""
from collections import defaultdict
n = list(n)
ord = sum(n)
need = (ord + 2)//2
rv = [1]*(n.pop() + 1)
rv.extend([0]*(need - len(rv)))
rv = rv[:need]
while n:
ni = n.pop()
N = ni + 1
was = rv[:]
for i in range(1, min(N, len(rv))):
rv[i] += rv[i - 1]
for i in range(N, need):
rv[i] += rv[i - 1] - was[i - N]
rev = list(reversed(rv))
if ord % 2:
rv = rv + rev
else:
rv[-1:] = rev
d = defaultdict(int)
for i in range(len(rv)):
d[i] = rv[i]
return d
def nC(n, k=None, replacement=False):
"""Return the number of combinations of ``n`` items taken ``k`` at a time.
Possible values for ``n``:
integer - set of length ``n``
sequence - converted to a multiset internally
multiset - {element: multiplicity}
If ``k`` is None then the total of all combinations of length 0
through the number of items represented in ``n`` will be returned.
If ``replacement`` is True then a given item can appear more than once
in the ``k`` items. (For example, for 'ab' sets of 2 would include 'aa',
'ab', and 'bb'.) The multiplicity of elements in ``n`` is ignored when
``replacement`` is True but the total number of elements is considered
since no element can appear more times than the number of elements in
``n``.
Examples
========
>>> from sympy.functions.combinatorial.numbers import nC
>>> from sympy.utilities.iterables import multiset_combinations
>>> nC(3, 2)
3
>>> nC('abc', 2)
3
>>> nC('aab', 2)
2
When ``replacement`` is True, each item can have multiplicity
equal to the length represented by ``n``:
>>> nC('aabc', replacement=True)
35
>>> [len(list(multiset_combinations('aaaabbbbcccc', i))) for i in range(5)]
[1, 3, 6, 10, 15]
>>> sum(_)
35
If there are ``k`` items with multiplicities ``m_1, m_2, ..., m_k``
then the total of all combinations of length 0 through ``k`` is the
product, ``(m_1 + 1)*(m_2 + 1)*...*(m_k + 1)``. When the multiplicity
of each item is 1 (i.e., k unique items) then there are 2**k
combinations. For example, if there are 4 unique items, the total number
of combinations is 16:
>>> sum(nC(4, i) for i in range(5))
16
See Also
========
sympy.utilities.iterables.multiset_combinations
References
==========
.. [1] https://en.wikipedia.org/wiki/Combination
.. [2] http://tinyurl.com/cep849r
"""
from sympy.functions.combinatorial.factorials import binomial
from sympy.core.mul import prod
if isinstance(n, SYMPY_INTS):
if k is None:
if not replacement:
return 2**n
return sum(nC(n, i, replacement) for i in range(n + 1))
if k < 0:
raise ValueError("k cannot be negative")
if replacement:
return binomial(n + k - 1, k)
return binomial(n, k)
if isinstance(n, _MultisetHistogram):
N = n[_N]
if k is None:
if not replacement:
return prod(m + 1 for m in n[_M])
return sum(nC(n, i, replacement) for i in range(N + 1))
elif replacement:
return nC(n[_ITEMS], k, replacement)
# assert k >= 0
elif k in (1, N - 1):
return n[_ITEMS]
elif k in (0, N):
return 1
return _AOP_product(tuple(n[_M]))[k]
else:
return nC(_multiset_histogram(n), k, replacement)
def _eval_stirling1(n, k):
if n == k == 0:
return S.One
if 0 in (n, k):
return S.Zero
# some special values
if n == k:
return S.One
elif k == n - 1:
return binomial(n, 2)
elif k == n - 2:
return (3*n - 1)*binomial(n, 3)/4
elif k == n - 3:
return binomial(n, 2)*binomial(n, 4)
return _stirling1(n, k)
@cacheit
def _stirling1(n, k):
row = [0, 1]+[0]*(k-1) # for n = 1
for i in range(2, n+1):
for j in range(min(k,i), 0, -1):
row[j] = (i-1) * row[j] + row[j-1]
return Integer(row[k])
def _eval_stirling2(n, k):
if n == k == 0:
return S.One
if 0 in (n, k):
return S.Zero
# some special values
if n == k:
return S.One
elif k == n - 1:
return binomial(n, 2)
elif k == 1:
return S.One
elif k == 2:
return Integer(2**(n - 1) - 1)
return _stirling2(n, k)
@cacheit
def _stirling2(n, k):
row = [0, 1]+[0]*(k-1) # for n = 1
for i in range(2, n+1):
for j in range(min(k,i), 0, -1):
row[j] = j * row[j] + row[j-1]
return Integer(row[k])
def stirling(n, k, d=None, kind=2, signed=False):
r"""Return Stirling number $S(n, k)$ of the first or second (default) kind.
The sum of all Stirling numbers of the second kind for $k = 1$
through $n$ is ``bell(n)``. The recurrence relationship for these numbers
is:
.. math :: {0 \brace 0} = 1; {n \brace 0} = {0 \brace k} = 0;
.. math :: {{n+1} \brace k} = j {n \brace k} + {n \brace {k-1}}
where $j$ is:
$n$ for Stirling numbers of the first kind,
$-n$ for signed Stirling numbers of the first kind,
$k$ for Stirling numbers of the second kind.
The first kind of Stirling number counts the number of permutations of
``n`` distinct items that have ``k`` cycles; the second kind counts the
ways in which ``n`` distinct items can be partitioned into ``k`` parts.
If ``d`` is given, the "reduced Stirling number of the second kind" is
returned: $S^{d}(n, k) = S(n - d + 1, k - d + 1)$ with $n \ge k \ge d$.
(This counts the ways to partition $n$ consecutive integers into $k$
groups with no pairwise difference less than $d$. See example below.)
To obtain the signed Stirling numbers of the first kind, use keyword
``signed=True``. Using this keyword automatically sets ``kind`` to 1.
Examples
========
>>> from sympy.functions.combinatorial.numbers import stirling, bell
>>> from sympy.combinatorics import Permutation
>>> from sympy.utilities.iterables import multiset_partitions, permutations
First kind (unsigned by default):
>>> [stirling(6, i, kind=1) for i in range(7)]
[0, 120, 274, 225, 85, 15, 1]
>>> perms = list(permutations(range(4)))
>>> [sum(Permutation(p).cycles == i for p in perms) for i in range(5)]
[0, 6, 11, 6, 1]
>>> [stirling(4, i, kind=1) for i in range(5)]
[0, 6, 11, 6, 1]
First kind (signed):
>>> [stirling(4, i, signed=True) for i in range(5)]
[0, -6, 11, -6, 1]
Second kind:
>>> [stirling(10, i) for i in range(12)]
[0, 1, 511, 9330, 34105, 42525, 22827, 5880, 750, 45, 1, 0]
>>> sum(_) == bell(10)
True
>>> len(list(multiset_partitions(range(4), 2))) == stirling(4, 2)
True
Reduced second kind:
>>> from sympy import subsets, oo
>>> def delta(p):
... if len(p) == 1:
... return oo
... return min(abs(i[0] - i[1]) for i in subsets(p, 2))
>>> parts = multiset_partitions(range(5), 3)
>>> d = 2
>>> sum(1 for p in parts if all(delta(i) >= d for i in p))
7
>>> stirling(5, 3, 2)
7
See Also
========
sympy.utilities.iterables.multiset_partitions
References
==========
.. [1] https://en.wikipedia.org/wiki/Stirling_numbers_of_the_first_kind
.. [2] https://en.wikipedia.org/wiki/Stirling_numbers_of_the_second_kind
"""
# TODO: make this a class like bell()
n = as_int(n)
k = as_int(k)
if n < 0:
raise ValueError('n must be nonnegative')
if k > n:
return S.Zero
if d:
# assert k >= d
# kind is ignored -- only kind=2 is supported
return _eval_stirling2(n - d + 1, k - d + 1)
elif signed:
# kind is ignored -- only kind=1 is supported
return (-1)**(n - k)*_eval_stirling1(n, k)
if kind == 1:
return _eval_stirling1(n, k)
elif kind == 2:
return _eval_stirling2(n, k)
else:
raise ValueError('kind must be 1 or 2, not %s' % k)
@cacheit
def _nT(n, k):
"""Return the partitions of ``n`` items into ``k`` parts. This
is used by ``nT`` for the case when ``n`` is an integer."""
# really quick exits
if k > n or k < 0:
return 0
if k == n or k == 1:
return 1
if k == 0:
return 0
# exits that could be done below but this is quicker
if k == 2:
return n//2
d = n - k
if d <= 3:
return d
# quick exit
if 3*k >= n: # or, equivalently, 2*k >= d
# all the information needed in this case
# will be in the cache needed to calculate
# partition(d), so...
# update cache
tot = partition._partition(d)
# and correct for values not needed
if d - k > 0:
tot -= sum(_npartition[:d - k])
return tot
# regular exit
# nT(n, k) = Sum(nT(n - k, m), (m, 1, k));
# calculate needed nT(i, j) values
p = [1]*d
for i in range(2, k + 1):
for m in range(i + 1, d):
p[m] += p[m - i]
d -= 1
# if p[0] were appended to the end of p then the last
# k values of p are the nT(n, j) values for 0 < j < k in reverse
# order p[-1] = nT(n, 1), p[-2] = nT(n, 2), etc.... Instead of
# putting the 1 from p[0] there, however, it is simply added to
# the sum below which is valid for 1 < k <= n//2
return (1 + sum(p[1 - k:]))
def nT(n, k=None):
"""Return the number of ``k``-sized partitions of ``n`` items.
Possible values for ``n``:
integer - ``n`` identical items
sequence - converted to a multiset internally
multiset - {element: multiplicity}
Note: the convention for ``nT`` is different than that of ``nC`` and
``nP`` in that
here an integer indicates ``n`` *identical* items instead of a set of
length ``n``; this is in keeping with the ``partitions`` function which
treats its integer-``n`` input like a list of ``n`` 1s. One can use
``range(n)`` for ``n`` to indicate ``n`` distinct items.
If ``k`` is None then the total number of ways to partition the elements
represented in ``n`` will be returned.
Examples
========
>>> from sympy.functions.combinatorial.numbers import nT
Partitions of the given multiset:
>>> [nT('aabbc', i) for i in range(1, 7)]
[1, 8, 11, 5, 1, 0]
>>> nT('aabbc') == sum(_)
True
>>> [nT("mississippi", i) for i in range(1, 12)]
[1, 74, 609, 1521, 1768, 1224, 579, 197, 50, 9, 1]
Partitions when all items are identical:
>>> [nT(5, i) for i in range(1, 6)]
[1, 2, 2, 1, 1]
>>> nT('1'*5) == sum(_)
True
When all items are different:
>>> [nT(range(5), i) for i in range(1, 6)]
[1, 15, 25, 10, 1]
>>> nT(range(5)) == sum(_)
True
Partitions of an integer expressed as a sum of positive integers:
>>> from sympy.functions.combinatorial.numbers import partition
>>> partition(4)
5
>>> nT(4, 1) + nT(4, 2) + nT(4, 3) + nT(4, 4)
5
>>> nT('1'*4)
5
See Also
========
sympy.utilities.iterables.partitions
sympy.utilities.iterables.multiset_partitions
sympy.functions.combinatorial.numbers.partition
References
==========
.. [1] http://undergraduate.csse.uwa.edu.au/units/CITS7209/partition.pdf
"""
from sympy.utilities.enumerative import MultisetPartitionTraverser
if isinstance(n, SYMPY_INTS):
# n identical items
if k is None:
return partition(n)
if isinstance(k, SYMPY_INTS):
n = as_int(n)
k = as_int(k)
return Integer(_nT(n, k))
if not isinstance(n, _MultisetHistogram):
try:
# if n contains hashable items there is some
# quick handling that can be done
u = len(set(n))
if u <= 1:
return nT(len(n), k)
elif u == len(n):
n = range(u)
raise TypeError
except TypeError:
n = _multiset_histogram(n)
N = n[_N]
if k is None and N == 1:
return 1
if k in (1, N):
return 1
if k == 2 or N == 2 and k is None:
m, r = divmod(N, 2)
rv = sum(nC(n, i) for i in range(1, m + 1))
if not r:
rv -= nC(n, m)//2
if k is None:
rv += 1 # for k == 1
return rv
if N == n[_ITEMS]:
# all distinct
if k is None:
return bell(N)
return stirling(N, k)
m = MultisetPartitionTraverser()
if k is None:
return m.count_partitions(n[_M])
# MultisetPartitionTraverser does not have a range-limited count
# method, so need to enumerate and count
tot = 0
for discard in m.enum_range(n[_M], k-1, k):
tot += 1
return tot
#-----------------------------------------------------------------------------#
# #
# Motzkin numbers #
# #
#-----------------------------------------------------------------------------#
class motzkin(Function):
"""
The nth Motzkin number is the number
of ways of drawing non-intersecting chords
between n points on a circle (not necessarily touching
every point by a chord). The Motzkin numbers are named
after Theodore Motzkin and have diverse applications
in geometry, combinatorics and number theory.
Motzkin numbers are the integer sequence defined by the
initial terms `M_0 = 1`, `M_1 = 1` and the two-term recurrence relation
`M_n = \frac{2*n + 1}{n + 2} * M_{n-1} + \frac{3n - 3}{n + 2} * M_{n-2}`.
Examples
========
>>> from sympy import motzkin
>>> motzkin.is_motzkin(5)
False
>>> motzkin.find_motzkin_numbers_in_range(2,300)
[2, 4, 9, 21, 51, 127]
>>> motzkin.find_motzkin_numbers_in_range(2,900)
[2, 4, 9, 21, 51, 127, 323, 835]
>>> motzkin.find_first_n_motzkins(10)
[1, 1, 2, 4, 9, 21, 51, 127, 323, 835]
References
==========
.. [1] https://en.wikipedia.org/wiki/Motzkin_number
.. [2] https://mathworld.wolfram.com/MotzkinNumber.html
"""
@staticmethod
def is_motzkin(n):
try:
n = as_int(n)
except ValueError:
return False
if n > 0:
if n == 1 or n == 2:
return True
tn1 = 1
tn = 2
i = 3
while tn < n:
a = ((2*i + 1)*tn + (3*i - 3)*tn1)/(i + 2)
i += 1
tn1 = tn
tn = a
if tn == n:
return True
else:
return False
else:
return False
@staticmethod
def find_motzkin_numbers_in_range(x, y):
if 0 <= x <= y:
motzkins = list()
if x <= 1 <= y:
motzkins.append(1)
tn1 = 1
tn = 2
i = 3
while tn <= y:
if tn >= x:
motzkins.append(tn)
a = ((2*i + 1)*tn + (3*i - 3)*tn1)/(i + 2)
i += 1
tn1 = tn
tn = int(a)
return motzkins
else:
raise ValueError('The provided range is not valid. This condition should satisfy x <= y')
@staticmethod
def find_first_n_motzkins(n):
try:
n = as_int(n)
except ValueError:
raise ValueError('The provided number must be a positive integer')
if n < 0:
raise ValueError('The provided number must be a positive integer')
motzkins = [1]
if n >= 1:
motzkins.append(1)
tn1 = 1
tn = 2
i = 3
while i <= n:
motzkins.append(tn)
a = ((2*i + 1)*tn + (3*i - 3)*tn1)/(i + 2)
i += 1
tn1 = tn
tn = int(a)
return motzkins
@staticmethod
@recurrence_memo([S.One, S.One])
def _motzkin(n, prev):
return ((2*n + 1)*prev[-1] + (3*n - 3)*prev[-2]) // (n + 2)
@classmethod
def eval(cls, n):
try:
n = as_int(n)
except ValueError:
raise ValueError('The provided number must be a positive integer')
if n < 0:
raise ValueError('The provided number must be a positive integer')
return Integer(cls._motzkin(n - 1))
|
04f4330e29314f798e714c1cec37bdd07be3297c4cfa40661347963e3a5916f2 | from typing import List
from functools import reduce
from sympy.core import S, sympify, Dummy, Mod
from sympy.core.cache import cacheit
from sympy.core.compatibility import HAS_GMPY
from sympy.core.function import Function, ArgumentIndexError, PoleError
from sympy.core.logic import fuzzy_and
from sympy.core.numbers import Integer, pi
from sympy.core.relational import Eq
from sympy.ntheory import sieve
from sympy.polys.polytools import Poly
from math import sqrt as _sqrt
class CombinatorialFunction(Function):
"""Base class for combinatorial functions. """
def _eval_simplify(self, **kwargs):
from sympy.simplify.combsimp import combsimp
# combinatorial function with non-integer arguments is
# automatically passed to gammasimp
expr = combsimp(self)
measure = kwargs['measure']
if measure(expr) <= kwargs['ratio']*measure(self):
return expr
return self
###############################################################################
######################## FACTORIAL and MULTI-FACTORIAL ########################
###############################################################################
class factorial(CombinatorialFunction):
r"""Implementation of factorial function over nonnegative integers.
By convention (consistent with the gamma function and the binomial
coefficients), factorial of a negative integer is complex infinity.
The factorial is very important in combinatorics where it gives
the number of ways in which `n` objects can be permuted. It also
arises in calculus, probability, number theory, etc.
There is strict relation of factorial with gamma function. In
fact `n! = gamma(n+1)` for nonnegative integers. Rewrite of this
kind is very useful in case of combinatorial simplification.
Computation of the factorial is done using two algorithms. For
small arguments a precomputed look up table is used. However for bigger
input algorithm Prime-Swing is used. It is the fastest algorithm
known and computes `n!` via prime factorization of special class
of numbers, called here the 'Swing Numbers'.
Examples
========
>>> from sympy import Symbol, factorial, S
>>> n = Symbol('n', integer=True)
>>> factorial(0)
1
>>> factorial(7)
5040
>>> factorial(-2)
zoo
>>> factorial(n)
factorial(n)
>>> factorial(2*n)
factorial(2*n)
>>> factorial(S(1)/2)
factorial(1/2)
See Also
========
factorial2, RisingFactorial, FallingFactorial
"""
def fdiff(self, argindex=1):
from sympy import gamma, polygamma
if argindex == 1:
return gamma(self.args[0] + 1)*polygamma(0, self.args[0] + 1)
else:
raise ArgumentIndexError(self, argindex)
_small_swing = [
1, 1, 1, 3, 3, 15, 5, 35, 35, 315, 63, 693, 231, 3003, 429, 6435, 6435, 109395,
12155, 230945, 46189, 969969, 88179, 2028117, 676039, 16900975, 1300075,
35102025, 5014575, 145422675, 9694845, 300540195, 300540195
]
_small_factorials = [] # type: List[int]
@classmethod
def _swing(cls, n):
if n < 33:
return cls._small_swing[n]
else:
N, primes = int(_sqrt(n)), []
for prime in sieve.primerange(3, N + 1):
p, q = 1, n
while True:
q //= prime
if q > 0:
if q & 1 == 1:
p *= prime
else:
break
if p > 1:
primes.append(p)
for prime in sieve.primerange(N + 1, n//3 + 1):
if (n // prime) & 1 == 1:
primes.append(prime)
L_product = R_product = 1
for prime in sieve.primerange(n//2 + 1, n + 1):
L_product *= prime
for prime in primes:
R_product *= prime
return L_product*R_product
@classmethod
def _recursive(cls, n):
if n < 2:
return 1
else:
return (cls._recursive(n//2)**2)*cls._swing(n)
@classmethod
def eval(cls, n):
n = sympify(n)
if n.is_Number:
if n.is_zero:
return S.One
elif n is S.Infinity:
return S.Infinity
elif n.is_Integer:
if n.is_negative:
return S.ComplexInfinity
else:
n = n.p
if n < 20:
if not cls._small_factorials:
result = 1
for i in range(1, 20):
result *= i
cls._small_factorials.append(result)
result = cls._small_factorials[n-1]
# GMPY factorial is faster, use it when available
elif HAS_GMPY:
from sympy.core.compatibility import gmpy
result = gmpy.fac(n)
else:
bits = bin(n).count('1')
result = cls._recursive(n)*2**(n - bits)
return Integer(result)
def _facmod(self, n, q):
res, N = 1, int(_sqrt(n))
# Exponent of prime p in n! is e_p(n) = [n/p] + [n/p**2] + ...
# for p > sqrt(n), e_p(n) < sqrt(n), the primes with [n/p] = m,
# occur consecutively and are grouped together in pw[m] for
# simultaneous exponentiation at a later stage
pw = [1]*N
m = 2 # to initialize the if condition below
for prime in sieve.primerange(2, n + 1):
if m > 1:
m, y = 0, n // prime
while y:
m += y
y //= prime
if m < N:
pw[m] = pw[m]*prime % q
else:
res = res*pow(prime, m, q) % q
for ex, bs in enumerate(pw):
if ex == 0 or bs == 1:
continue
if bs == 0:
return 0
res = res*pow(bs, ex, q) % q
return res
def _eval_Mod(self, q):
n = self.args[0]
if n.is_integer and n.is_nonnegative and q.is_integer:
aq = abs(q)
d = aq - n
if d.is_nonpositive:
return S.Zero
else:
isprime = aq.is_prime
if d == 1:
# Apply Wilson's theorem (if a natural number n > 1
# is a prime number, then (n-1)! = -1 mod n) and
# its inverse (if n > 4 is a composite number, then
# (n-1)! = 0 mod n)
if isprime:
return S(-1 % q)
elif isprime is False and (aq - 6).is_nonnegative:
return S.Zero
elif n.is_Integer and q.is_Integer:
n, d, aq = map(int, (n, d, aq))
if isprime and (d - 1 < n):
fc = self._facmod(d - 1, aq)
fc = pow(fc, aq - 2, aq)
if d%2:
fc = -fc
else:
fc = self._facmod(n, aq)
return S(fc % q)
def _eval_rewrite_as_gamma(self, n, piecewise=True, **kwargs):
from sympy import gamma
return gamma(n + 1)
def _eval_rewrite_as_Product(self, n, **kwargs):
from sympy import Product
if n.is_nonnegative and n.is_integer:
i = Dummy('i', integer=True)
return Product(i, (i, 1, n))
def _eval_is_integer(self):
if self.args[0].is_integer and self.args[0].is_nonnegative:
return True
def _eval_is_positive(self):
if self.args[0].is_integer and self.args[0].is_nonnegative:
return True
def _eval_is_even(self):
x = self.args[0]
if x.is_integer and x.is_nonnegative:
return (x - 2).is_nonnegative
def _eval_is_composite(self):
x = self.args[0]
if x.is_integer and x.is_nonnegative:
return (x - 3).is_nonnegative
def _eval_is_real(self):
x = self.args[0]
if x.is_nonnegative or x.is_noninteger:
return True
def _eval_as_leading_term(self, x, logx=None, cdir=0):
arg = self.args[0].as_leading_term(x)
arg0 = arg.subs(x, 0)
if arg0.is_zero:
return S.One
elif not arg0.is_infinite:
return self.func(arg)
raise PoleError("Cannot expand %s around 0" % (self))
class MultiFactorial(CombinatorialFunction):
pass
class subfactorial(CombinatorialFunction):
r"""The subfactorial counts the derangements of n items and is
defined for non-negative integers as:
.. math:: !n = \begin{cases} 1 & n = 0 \\ 0 & n = 1 \\
(n-1)(!(n-1) + !(n-2)) & n > 1 \end{cases}
It can also be written as ``int(round(n!/exp(1)))`` but the
recursive definition with caching is implemented for this function.
An interesting analytic expression is the following [2]_
.. math:: !x = \Gamma(x + 1, -1)/e
which is valid for non-negative integers `x`. The above formula
is not very useful incase of non-integers. :math:`\Gamma(x + 1, -1)` is
single-valued only for integral arguments `x`, elsewhere on the positive
real axis it has an infinite number of branches none of which are real.
References
==========
.. [1] https://en.wikipedia.org/wiki/Subfactorial
.. [2] http://mathworld.wolfram.com/Subfactorial.html
Examples
========
>>> from sympy import subfactorial
>>> from sympy.abc import n
>>> subfactorial(n + 1)
subfactorial(n + 1)
>>> subfactorial(5)
44
See Also
========
sympy.functions.combinatorial.factorials.factorial,
sympy.utilities.iterables.generate_derangements,
sympy.functions.special.gamma_functions.uppergamma
"""
@classmethod
@cacheit
def _eval(self, n):
if not n:
return S.One
elif n == 1:
return S.Zero
else:
z1, z2 = 1, 0
for i in range(2, n + 1):
z1, z2 = z2, (i - 1)*(z2 + z1)
return z2
@classmethod
def eval(cls, arg):
if arg.is_Number:
if arg.is_Integer and arg.is_nonnegative:
return cls._eval(arg)
elif arg is S.NaN:
return S.NaN
elif arg is S.Infinity:
return S.Infinity
def _eval_is_even(self):
if self.args[0].is_odd and self.args[0].is_nonnegative:
return True
def _eval_is_integer(self):
if self.args[0].is_integer and self.args[0].is_nonnegative:
return True
def _eval_rewrite_as_factorial(self, arg, **kwargs):
from sympy import summation
i = Dummy('i')
f = S.NegativeOne**i / factorial(i)
return factorial(arg) * summation(f, (i, 0, arg))
def _eval_rewrite_as_gamma(self, arg, piecewise=True, **kwargs):
from sympy import exp, gamma, I, lowergamma
return ((-1)**(arg + 1)*exp(-I*pi*arg)*lowergamma(arg + 1, -1) + gamma(arg + 1))*exp(-1)
def _eval_rewrite_as_uppergamma(self, arg, **kwargs):
from sympy import uppergamma
return uppergamma(arg + 1, -1)/S.Exp1
def _eval_is_nonnegative(self):
if self.args[0].is_integer and self.args[0].is_nonnegative:
return True
def _eval_is_odd(self):
if self.args[0].is_even and self.args[0].is_nonnegative:
return True
class factorial2(CombinatorialFunction):
r"""The double factorial `n!!`, not to be confused with `(n!)!`
The double factorial is defined for nonnegative integers and for odd
negative integers as:
.. math:: n!! = \begin{cases} 1 & n = 0 \\
n(n-2)(n-4) \cdots 1 & n\ \text{positive odd} \\
n(n-2)(n-4) \cdots 2 & n\ \text{positive even} \\
(n+2)!!/(n+2) & n\ \text{negative odd} \end{cases}
References
==========
.. [1] https://en.wikipedia.org/wiki/Double_factorial
Examples
========
>>> from sympy import factorial2, var
>>> n = var('n')
>>> n
n
>>> factorial2(n + 1)
factorial2(n + 1)
>>> factorial2(5)
15
>>> factorial2(-1)
1
>>> factorial2(-5)
1/3
See Also
========
factorial, RisingFactorial, FallingFactorial
"""
@classmethod
def eval(cls, arg):
# TODO: extend this to complex numbers?
if arg.is_Number:
if not arg.is_Integer:
raise ValueError("argument must be nonnegative integer "
"or negative odd integer")
# This implementation is faster than the recursive one
# It also avoids "maximum recursion depth exceeded" runtime error
if arg.is_nonnegative:
if arg.is_even:
k = arg / 2
return 2**k * factorial(k)
return factorial(arg) / factorial2(arg - 1)
if arg.is_odd:
return arg*(S.NegativeOne)**((1 - arg)/2) / factorial2(-arg)
raise ValueError("argument must be nonnegative integer "
"or negative odd integer")
def _eval_is_even(self):
# Double factorial is even for every positive even input
n = self.args[0]
if n.is_integer:
if n.is_odd:
return False
if n.is_even:
if n.is_positive:
return True
if n.is_zero:
return False
def _eval_is_integer(self):
# Double factorial is an integer for every nonnegative input, and for
# -1 and -3
n = self.args[0]
if n.is_integer:
if (n + 1).is_nonnegative:
return True
if n.is_odd:
return (n + 3).is_nonnegative
def _eval_is_odd(self):
# Double factorial is odd for every odd input not smaller than -3, and
# for 0
n = self.args[0]
if n.is_odd:
return (n + 3).is_nonnegative
if n.is_even:
if n.is_positive:
return False
if n.is_zero:
return True
def _eval_is_positive(self):
# Double factorial is positive for every nonnegative input, and for
# every odd negative input which is of the form -1-4k for an
# nonnegative integer k
n = self.args[0]
if n.is_integer:
if (n + 1).is_nonnegative:
return True
if n.is_odd:
return ((n + 1) / 2).is_even
def _eval_rewrite_as_gamma(self, n, piecewise=True, **kwargs):
from sympy import gamma, Piecewise, sqrt
return 2**(n/2)*gamma(n/2 + 1) * Piecewise((1, Eq(Mod(n, 2), 0)),
(sqrt(2/pi), Eq(Mod(n, 2), 1)))
###############################################################################
######################## RISING and FALLING FACTORIALS ########################
###############################################################################
class RisingFactorial(CombinatorialFunction):
r"""
Rising factorial (also called Pochhammer symbol) is a double valued
function arising in concrete mathematics, hypergeometric functions
and series expansions. It is defined by:
.. math:: rf(x,k) = x \cdot (x+1) \cdots (x+k-1)
where `x` can be arbitrary expression and `k` is an integer. For
more information check "Concrete mathematics" by Graham, pp. 66
or visit http://mathworld.wolfram.com/RisingFactorial.html page.
When `x` is a Poly instance of degree >= 1 with a single variable,
`rf(x,k) = x(y) \cdot x(y+1) \cdots x(y+k-1)`, where `y` is the
variable of `x`. This is as described in Peter Paule, "Greatest
Factorial Factorization and Symbolic Summation", Journal of
Symbolic Computation, vol. 20, pp. 235-268, 1995.
Examples
========
>>> from sympy import rf, Poly
>>> from sympy.abc import x
>>> rf(x, 0)
1
>>> rf(1, 5)
120
>>> rf(x, 5) == x*(1 + x)*(2 + x)*(3 + x)*(4 + x)
True
>>> rf(Poly(x**3, x), 2)
Poly(x**6 + 3*x**5 + 3*x**4 + x**3, x, domain='ZZ')
Rewriting is complicated unless the relationship between
the arguments is known, but rising factorial can
be rewritten in terms of gamma, factorial and binomial
and falling factorial.
>>> from sympy import Symbol, factorial, ff, binomial, gamma
>>> n = Symbol('n', integer=True, positive=True)
>>> R = rf(n, n + 2)
>>> for i in (rf, ff, factorial, binomial, gamma):
... R.rewrite(i)
...
RisingFactorial(n, n + 2)
FallingFactorial(2*n + 1, n + 2)
factorial(2*n + 1)/factorial(n - 1)
binomial(2*n + 1, n + 2)*factorial(n + 2)
gamma(2*n + 2)/gamma(n)
See Also
========
factorial, factorial2, FallingFactorial
References
==========
.. [1] https://en.wikipedia.org/wiki/Pochhammer_symbol
"""
@classmethod
def eval(cls, x, k):
x = sympify(x)
k = sympify(k)
if x is S.NaN or k is S.NaN:
return S.NaN
elif x is S.One:
return factorial(k)
elif k.is_Integer:
if k.is_zero:
return S.One
else:
if k.is_positive:
if x is S.Infinity:
return S.Infinity
elif x is S.NegativeInfinity:
if k.is_odd:
return S.NegativeInfinity
else:
return S.Infinity
else:
if isinstance(x, Poly):
gens = x.gens
if len(gens)!= 1:
raise ValueError("rf only defined for "
"polynomials on one generator")
else:
return reduce(lambda r, i:
r*(x.shift(i)),
range(0, int(k)), 1)
else:
return reduce(lambda r, i: r*(x + i),
range(0, int(k)), 1)
else:
if x is S.Infinity:
return S.Infinity
elif x is S.NegativeInfinity:
return S.Infinity
else:
if isinstance(x, Poly):
gens = x.gens
if len(gens)!= 1:
raise ValueError("rf only defined for "
"polynomials on one generator")
else:
return 1/reduce(lambda r, i:
r*(x.shift(-i)),
range(1, abs(int(k)) + 1), 1)
else:
return 1/reduce(lambda r, i:
r*(x - i),
range(1, abs(int(k)) + 1), 1)
if k.is_integer == False:
if x.is_integer and x.is_negative:
return S.Zero
def _eval_rewrite_as_gamma(self, x, k, piecewise=True, **kwargs):
from sympy import gamma, Piecewise
if not piecewise:
if (x <= 0) == True:
return (-1)**k*gamma(1 - x) / gamma(-k - x + 1)
return gamma(x + k) / gamma(x)
return Piecewise(
(gamma(x + k) / gamma(x), x > 0),
((-1)**k*gamma(1 - x) / gamma(-k - x + 1), True))
def _eval_rewrite_as_FallingFactorial(self, x, k, **kwargs):
return FallingFactorial(x + k - 1, k)
def _eval_rewrite_as_factorial(self, x, k, **kwargs):
from sympy import Piecewise
if x.is_integer and k.is_integer:
return Piecewise(
(factorial(k + x - 1)/factorial(x - 1), x > 0),
((-1)**k*factorial(-x)/factorial(-k - x), True))
def _eval_rewrite_as_binomial(self, x, k, **kwargs):
if k.is_integer:
return factorial(k) * binomial(x + k - 1, k)
def _eval_rewrite_as_tractable(self, x, k, limitvar=None, **kwargs):
from sympy import gamma
if limitvar:
k_lim = k.subs(limitvar, S.Infinity)
if k_lim is S.Infinity:
return (gamma(x + k).rewrite('tractable', deep=True) / gamma(x))
elif k_lim is S.NegativeInfinity:
return ((-1)**k*gamma(1 - x) / gamma(-k - x + 1).rewrite('tractable', deep=True))
return self.rewrite(gamma).rewrite('tractable', deep=True)
def _eval_is_integer(self):
return fuzzy_and((self.args[0].is_integer, self.args[1].is_integer,
self.args[1].is_nonnegative))
def _sage_(self):
import sage.all as sage
return sage.rising_factorial(self.args[0]._sage_(),
self.args[1]._sage_())
class FallingFactorial(CombinatorialFunction):
r"""
Falling factorial (related to rising factorial) is a double valued
function arising in concrete mathematics, hypergeometric functions
and series expansions. It is defined by
.. math:: ff(x,k) = x \cdot (x-1) \cdots (x-k+1)
where `x` can be arbitrary expression and `k` is an integer. For
more information check "Concrete mathematics" by Graham, pp. 66
or visit http://mathworld.wolfram.com/FallingFactorial.html page.
When `x` is a Poly instance of degree >= 1 with single variable,
`ff(x,k) = x(y) \cdot x(y-1) \cdots x(y-k+1)`, where `y` is the
variable of `x`. This is as described in Peter Paule, "Greatest
Factorial Factorization and Symbolic Summation", Journal of
Symbolic Computation, vol. 20, pp. 235-268, 1995.
>>> from sympy import ff, Poly, Symbol
>>> from sympy.abc import x
>>> n = Symbol('n', integer=True)
>>> ff(x, 0)
1
>>> ff(5, 5)
120
>>> ff(x, 5) == x*(x - 1)*(x - 2)*(x - 3)*(x - 4)
True
>>> ff(Poly(x**2, x), 2)
Poly(x**4 - 2*x**3 + x**2, x, domain='ZZ')
>>> ff(n, n)
factorial(n)
Rewriting is complicated unless the relationship between
the arguments is known, but falling factorial can
be rewritten in terms of gamma, factorial and binomial
and rising factorial.
>>> from sympy import factorial, rf, gamma, binomial, Symbol
>>> n = Symbol('n', integer=True, positive=True)
>>> F = ff(n, n - 2)
>>> for i in (rf, ff, factorial, binomial, gamma):
... F.rewrite(i)
...
RisingFactorial(3, n - 2)
FallingFactorial(n, n - 2)
factorial(n)/2
binomial(n, n - 2)*factorial(n - 2)
gamma(n + 1)/2
See Also
========
factorial, factorial2, RisingFactorial
References
==========
.. [1] http://mathworld.wolfram.com/FallingFactorial.html
"""
@classmethod
def eval(cls, x, k):
x = sympify(x)
k = sympify(k)
if x is S.NaN or k is S.NaN:
return S.NaN
elif k.is_integer and x == k:
return factorial(x)
elif k.is_Integer:
if k.is_zero:
return S.One
else:
if k.is_positive:
if x is S.Infinity:
return S.Infinity
elif x is S.NegativeInfinity:
if k.is_odd:
return S.NegativeInfinity
else:
return S.Infinity
else:
if isinstance(x, Poly):
gens = x.gens
if len(gens)!= 1:
raise ValueError("ff only defined for "
"polynomials on one generator")
else:
return reduce(lambda r, i:
r*(x.shift(-i)),
range(0, int(k)), 1)
else:
return reduce(lambda r, i: r*(x - i),
range(0, int(k)), 1)
else:
if x is S.Infinity:
return S.Infinity
elif x is S.NegativeInfinity:
return S.Infinity
else:
if isinstance(x, Poly):
gens = x.gens
if len(gens)!= 1:
raise ValueError("rf only defined for "
"polynomials on one generator")
else:
return 1/reduce(lambda r, i:
r*(x.shift(i)),
range(1, abs(int(k)) + 1), 1)
else:
return 1/reduce(lambda r, i: r*(x + i),
range(1, abs(int(k)) + 1), 1)
def _eval_rewrite_as_gamma(self, x, k, piecewise=True, **kwargs):
from sympy import gamma, Piecewise
if not piecewise:
if (x < 0) == True:
return (-1)**k*gamma(k - x) / gamma(-x)
return gamma(x + 1) / gamma(x - k + 1)
return Piecewise(
(gamma(x + 1) / gamma(x - k + 1), x >= 0),
((-1)**k*gamma(k - x) / gamma(-x), True))
def _eval_rewrite_as_RisingFactorial(self, x, k, **kwargs):
return rf(x - k + 1, k)
def _eval_rewrite_as_binomial(self, x, k, **kwargs):
if k.is_integer:
return factorial(k) * binomial(x, k)
def _eval_rewrite_as_factorial(self, x, k, **kwargs):
from sympy import Piecewise
if x.is_integer and k.is_integer:
return Piecewise(
(factorial(x)/factorial(-k + x), x >= 0),
((-1)**k*factorial(k - x - 1)/factorial(-x - 1), True))
def _eval_rewrite_as_tractable(self, x, k, limitvar=None, **kwargs):
from sympy import gamma
if limitvar:
k_lim = k.subs(limitvar, S.Infinity)
if k_lim is S.Infinity:
return ((-1)**k*gamma(k - x).rewrite('tractable', deep=True) / gamma(-x))
elif k_lim is S.NegativeInfinity:
return (gamma(x + 1) / gamma(x - k + 1).rewrite('tractable', deep=True))
return self.rewrite(gamma).rewrite('tractable', deep=True)
def _eval_is_integer(self):
return fuzzy_and((self.args[0].is_integer, self.args[1].is_integer,
self.args[1].is_nonnegative))
def _sage_(self):
import sage.all as sage
return sage.falling_factorial(self.args[0]._sage_(),
self.args[1]._sage_())
rf = RisingFactorial
ff = FallingFactorial
###############################################################################
########################### BINOMIAL COEFFICIENTS #############################
###############################################################################
class binomial(CombinatorialFunction):
r"""Implementation of the binomial coefficient. It can be defined
in two ways depending on its desired interpretation:
.. math:: \binom{n}{k} = \frac{n!}{k!(n-k)!}\ \text{or}\
\binom{n}{k} = \frac{ff(n, k)}{k!}
First, in a strict combinatorial sense it defines the
number of ways we can choose `k` elements from a set of
`n` elements. In this case both arguments are nonnegative
integers and binomial is computed using an efficient
algorithm based on prime factorization.
The other definition is generalization for arbitrary `n`,
however `k` must also be nonnegative. This case is very
useful when evaluating summations.
For the sake of convenience for negative integer `k` this function
will return zero no matter what valued is the other argument.
To expand the binomial when `n` is a symbol, use either
``expand_func()`` or ``expand(func=True)``. The former will keep
the polynomial in factored form while the latter will expand the
polynomial itself. See examples for details.
Examples
========
>>> from sympy import Symbol, Rational, binomial, expand_func
>>> n = Symbol('n', integer=True, positive=True)
>>> binomial(15, 8)
6435
>>> binomial(n, -1)
0
Rows of Pascal's triangle can be generated with the binomial function:
>>> for N in range(8):
... print([binomial(N, i) for i in range(N + 1)])
...
[1]
[1, 1]
[1, 2, 1]
[1, 3, 3, 1]
[1, 4, 6, 4, 1]
[1, 5, 10, 10, 5, 1]
[1, 6, 15, 20, 15, 6, 1]
[1, 7, 21, 35, 35, 21, 7, 1]
As can a given diagonal, e.g. the 4th diagonal:
>>> N = -4
>>> [binomial(N, i) for i in range(1 - N)]
[1, -4, 10, -20, 35]
>>> binomial(Rational(5, 4), 3)
-5/128
>>> binomial(Rational(-5, 4), 3)
-195/128
>>> binomial(n, 3)
binomial(n, 3)
>>> binomial(n, 3).expand(func=True)
n**3/6 - n**2/2 + n/3
>>> expand_func(binomial(n, 3))
n*(n - 2)*(n - 1)/6
References
==========
.. [1] https://www.johndcook.com/blog/binomial_coefficients/
"""
def fdiff(self, argindex=1):
from sympy import polygamma
if argindex == 1:
# http://functions.wolfram.com/GammaBetaErf/Binomial/20/01/01/
n, k = self.args
return binomial(n, k)*(polygamma(0, n + 1) - \
polygamma(0, n - k + 1))
elif argindex == 2:
# http://functions.wolfram.com/GammaBetaErf/Binomial/20/01/02/
n, k = self.args
return binomial(n, k)*(polygamma(0, n - k + 1) - \
polygamma(0, k + 1))
else:
raise ArgumentIndexError(self, argindex)
@classmethod
def _eval(self, n, k):
# n.is_Number and k.is_Integer and k != 1 and n != k
if k.is_Integer:
if n.is_Integer and n >= 0:
n, k = int(n), int(k)
if k > n:
return S.Zero
elif k > n // 2:
k = n - k
if HAS_GMPY:
from sympy.core.compatibility import gmpy
return Integer(gmpy.bincoef(n, k))
d, result = n - k, 1
for i in range(1, k + 1):
d += 1
result = result * d // i
return Integer(result)
else:
d, result = n - k, 1
for i in range(1, k + 1):
d += 1
result *= d
result /= i
return result
@classmethod
def eval(cls, n, k):
n, k = map(sympify, (n, k))
d = n - k
n_nonneg, n_isint = n.is_nonnegative, n.is_integer
if k.is_zero or ((n_nonneg or n_isint is False)
and d.is_zero):
return S.One
if (k - 1).is_zero or ((n_nonneg or n_isint is False)
and (d - 1).is_zero):
return n
if k.is_integer:
if k.is_negative or (n_nonneg and n_isint and d.is_negative):
return S.Zero
elif n.is_number:
res = cls._eval(n, k)
return res.expand(basic=True) if res else res
elif n_nonneg is False and n_isint:
# a special case when binomial evaluates to complex infinity
return S.ComplexInfinity
elif k.is_number:
from sympy import gamma
return gamma(n + 1)/(gamma(k + 1)*gamma(n - k + 1))
def _eval_Mod(self, q):
n, k = self.args
if any(x.is_integer is False for x in (n, k, q)):
raise ValueError("Integers expected for binomial Mod")
if all(x.is_Integer for x in (n, k, q)):
n, k = map(int, (n, k))
aq, res = abs(q), 1
# handle negative integers k or n
if k < 0:
return S.Zero
if n < 0:
n = -n + k - 1
res = -1 if k%2 else 1
# non negative integers k and n
if k > n:
return S.Zero
isprime = aq.is_prime
aq = int(aq)
if isprime:
if aq < n:
# use Lucas Theorem
N, K = n, k
while N or K:
res = res*binomial(N % aq, K % aq) % aq
N, K = N // aq, K // aq
else:
# use Factorial Modulo
d = n - k
if k > d:
k, d = d, k
kf = 1
for i in range(2, k + 1):
kf = kf*i % aq
df = kf
for i in range(k + 1, d + 1):
df = df*i % aq
res *= df
for i in range(d + 1, n + 1):
res = res*i % aq
res *= pow(kf*df % aq, aq - 2, aq)
res %= aq
else:
# Binomial Factorization is performed by calculating the
# exponents of primes <= n in `n! /(k! (n - k)!)`,
# for non-negative integers n and k. As the exponent of
# prime in n! is e_p(n) = [n/p] + [n/p**2] + ...
# the exponent of prime in binomial(n, k) would be
# e_p(n) - e_p(k) - e_p(n - k)
M = int(_sqrt(n))
for prime in sieve.primerange(2, n + 1):
if prime > n - k:
res = res*prime % aq
elif prime > n // 2:
continue
elif prime > M:
if n % prime < k % prime:
res = res*prime % aq
else:
N, K = n, k
exp = a = 0
while N > 0:
a = int((N % prime) < (K % prime + a))
N, K = N // prime, K // prime
exp += a
if exp > 0:
res *= pow(prime, exp, aq)
res %= aq
return S(res % q)
def _eval_expand_func(self, **hints):
"""
Function to expand binomial(n, k) when m is positive integer
Also,
n is self.args[0] and k is self.args[1] while using binomial(n, k)
"""
n = self.args[0]
if n.is_Number:
return binomial(*self.args)
k = self.args[1]
if (n-k).is_Integer:
k = n - k
if k.is_Integer:
if k.is_zero:
return S.One
elif k.is_negative:
return S.Zero
else:
n, result = self.args[0], 1
for i in range(1, k + 1):
result *= n - k + i
result /= i
return result
else:
return binomial(*self.args)
def _eval_rewrite_as_factorial(self, n, k, **kwargs):
return factorial(n)/(factorial(k)*factorial(n - k))
def _eval_rewrite_as_gamma(self, n, k, piecewise=True, **kwargs):
from sympy import gamma
return gamma(n + 1)/(gamma(k + 1)*gamma(n - k + 1))
def _eval_rewrite_as_tractable(self, n, k, limitvar=None, **kwargs):
return self._eval_rewrite_as_gamma(n, k).rewrite('tractable')
def _eval_rewrite_as_FallingFactorial(self, n, k, **kwargs):
if k.is_integer:
return ff(n, k) / factorial(k)
def _eval_is_integer(self):
n, k = self.args
if n.is_integer and k.is_integer:
return True
elif k.is_integer is False:
return False
def _eval_is_nonnegative(self):
n, k = self.args
if n.is_integer and k.is_integer:
if n.is_nonnegative or k.is_negative or k.is_even:
return True
elif k.is_even is False:
return False
def _eval_as_leading_term(self, x, logx=None, cdir=0):
from sympy import gamma
return self.rewrite(gamma)._eval_as_leading_term(x, logx=logx, cdir=cdir)
|
fca6cbef8ba0f26ed04d38c7eecfd70819920fc4f40d4bc0d69f6837bfd25970 | from typing import Tuple
from sympy.core.add import Add
from sympy.core.basic import sympify, cacheit
from sympy.core.expr import Expr
from sympy.core.function import Function, ArgumentIndexError, PoleError, expand_mul
from sympy.core.logic import fuzzy_not, fuzzy_or, FuzzyBool
from sympy.core.numbers import igcdex, Rational, pi
from sympy.core.relational import Ne
from sympy.core.singleton import S
from sympy.core.symbol import Symbol
from sympy.functions.combinatorial.factorials import factorial, RisingFactorial
from sympy.functions.elementary.exponential import log, exp
from sympy.functions.elementary.integers import floor
from sympy.functions.elementary.hyperbolic import (acoth, asinh, atanh, cosh,
coth, HyperbolicFunction, sinh, tanh)
from sympy.functions.elementary.miscellaneous import sqrt, Min, Max
from sympy.functions.elementary.piecewise import Piecewise
from sympy.sets.sets import FiniteSet
from sympy.utilities.iterables import numbered_symbols
###############################################################################
########################## TRIGONOMETRIC FUNCTIONS ############################
###############################################################################
class TrigonometricFunction(Function):
"""Base class for trigonometric functions. """
unbranched = True
_singularities = (S.ComplexInfinity,)
def _eval_is_rational(self):
s = self.func(*self.args)
if s.func == self.func:
if s.args[0].is_rational and fuzzy_not(s.args[0].is_zero):
return False
else:
return s.is_rational
def _eval_is_algebraic(self):
s = self.func(*self.args)
if s.func == self.func:
if fuzzy_not(self.args[0].is_zero) and self.args[0].is_algebraic:
return False
pi_coeff = _pi_coeff(self.args[0])
if pi_coeff is not None and pi_coeff.is_rational:
return True
else:
return s.is_algebraic
def _eval_expand_complex(self, deep=True, **hints):
re_part, im_part = self.as_real_imag(deep=deep, **hints)
return re_part + im_part*S.ImaginaryUnit
def _as_real_imag(self, deep=True, **hints):
if self.args[0].is_extended_real:
if deep:
hints['complex'] = False
return (self.args[0].expand(deep, **hints), S.Zero)
else:
return (self.args[0], S.Zero)
if deep:
re, im = self.args[0].expand(deep, **hints).as_real_imag()
else:
re, im = self.args[0].as_real_imag()
return (re, im)
def _period(self, general_period, symbol=None):
f = expand_mul(self.args[0])
if symbol is None:
symbol = tuple(f.free_symbols)[0]
if not f.has(symbol):
return S.Zero
if f == symbol:
return general_period
if symbol in f.free_symbols:
if f.is_Mul:
g, h = f.as_independent(symbol)
if h == symbol:
return general_period/abs(g)
if f.is_Add:
a, h = f.as_independent(symbol)
g, h = h.as_independent(symbol, as_Add=False)
if h == symbol:
return general_period/abs(g)
raise NotImplementedError("Use the periodicity function instead.")
def _peeloff_pi(arg):
"""
Split ARG into two parts, a "rest" and a multiple of pi/2.
This assumes ARG to be an Add.
The multiple of pi returned in the second position is always a Rational.
Examples
========
>>> from sympy.functions.elementary.trigonometric import _peeloff_pi as peel
>>> from sympy import pi
>>> from sympy.abc import x, y
>>> peel(x + pi/2)
(x, pi/2)
>>> peel(x + 2*pi/3 + pi*y)
(x + pi*y + pi/6, pi/2)
"""
pi_coeff = S.Zero
rest_terms = []
for a in Add.make_args(arg):
K = a.coeff(S.Pi)
if K and K.is_rational:
pi_coeff += K
else:
rest_terms.append(a)
if pi_coeff is S.Zero:
return arg, S.Zero
m1 = (pi_coeff % S.Half)*S.Pi
m2 = pi_coeff*S.Pi - m1
final_coeff = m2 / S.Pi
if final_coeff.is_integer or ((2*final_coeff).is_integer
and final_coeff.is_even is False):
return Add(*(rest_terms + [m1])), m2
return arg, S.Zero
def _pi_coeff(arg, cycles=1):
"""
When arg is a Number times pi (e.g. 3*pi/2) then return the Number
normalized to be in the range [0, 2], else None.
When an even multiple of pi is encountered, if it is multiplying
something with known parity then the multiple is returned as 0 otherwise
as 2.
Examples
========
>>> from sympy.functions.elementary.trigonometric import _pi_coeff as coeff
>>> from sympy import pi, Dummy
>>> from sympy.abc import x
>>> coeff(3*x*pi)
3*x
>>> coeff(11*pi/7)
11/7
>>> coeff(-11*pi/7)
3/7
>>> coeff(4*pi)
0
>>> coeff(5*pi)
1
>>> coeff(5.0*pi)
1
>>> coeff(5.5*pi)
3/2
>>> coeff(2 + pi)
>>> coeff(2*Dummy(integer=True)*pi)
2
>>> coeff(2*Dummy(even=True)*pi)
0
"""
arg = sympify(arg)
if arg is S.Pi:
return S.One
elif not arg:
return S.Zero
elif arg.is_Mul:
cx = arg.coeff(S.Pi)
if cx:
c, x = cx.as_coeff_Mul() # pi is not included as coeff
if c.is_Float:
# recast exact binary fractions to Rationals
f = abs(c) % 1
if f != 0:
p = -int(round(log(f, 2).evalf()))
m = 2**p
cm = c*m
i = int(cm)
if i == cm:
c = Rational(i, m)
cx = c*x
else:
c = Rational(int(c))
cx = c*x
if x.is_integer:
c2 = c % 2
if c2 == 1:
return x
elif not c2:
if x.is_even is not None: # known parity
return S.Zero
return S(2)
else:
return c2*x
return cx
elif arg.is_zero:
return S.Zero
class sin(TrigonometricFunction):
"""
The sine function.
Returns the sine of x (measured in radians).
Explanation
===========
This function will evaluate automatically in the
case x/pi is some rational number [4]_. For example,
if x is a multiple of pi, pi/2, pi/3, pi/4 and pi/6.
Examples
========
>>> from sympy import sin, pi
>>> from sympy.abc import x
>>> sin(x**2).diff(x)
2*x*cos(x**2)
>>> sin(1).diff(x)
0
>>> sin(pi)
0
>>> sin(pi/2)
1
>>> sin(pi/6)
1/2
>>> sin(pi/12)
-sqrt(2)/4 + sqrt(6)/4
See Also
========
csc, cos, sec, tan, cot
asin, acsc, acos, asec, atan, acot, atan2
References
==========
.. [1] https://en.wikipedia.org/wiki/Trigonometric_functions
.. [2] http://dlmf.nist.gov/4.14
.. [3] http://functions.wolfram.com/ElementaryFunctions/Sin
.. [4] http://mathworld.wolfram.com/TrigonometryAngles.html
"""
def period(self, symbol=None):
return self._period(2*pi, symbol)
def fdiff(self, argindex=1):
if argindex == 1:
return cos(self.args[0])
else:
raise ArgumentIndexError(self, argindex)
@classmethod
def eval(cls, arg):
from sympy.calculus import AccumBounds
from sympy.sets.setexpr import SetExpr
if arg.is_Number:
if arg is S.NaN:
return S.NaN
elif arg.is_zero:
return S.Zero
elif arg is S.Infinity or arg is S.NegativeInfinity:
return AccumBounds(-1, 1)
if arg is S.ComplexInfinity:
return S.NaN
if isinstance(arg, AccumBounds):
min, max = arg.min, arg.max
d = floor(min/(2*S.Pi))
if min is not S.NegativeInfinity:
min = min - d*2*S.Pi
if max is not S.Infinity:
max = max - d*2*S.Pi
if AccumBounds(min, max).intersection(FiniteSet(S.Pi/2, S.Pi*Rational(5, 2))) \
is not S.EmptySet and \
AccumBounds(min, max).intersection(FiniteSet(S.Pi*Rational(3, 2),
S.Pi*Rational(7, 2))) is not S.EmptySet:
return AccumBounds(-1, 1)
elif AccumBounds(min, max).intersection(FiniteSet(S.Pi/2, S.Pi*Rational(5, 2))) \
is not S.EmptySet:
return AccumBounds(Min(sin(min), sin(max)), 1)
elif AccumBounds(min, max).intersection(FiniteSet(S.Pi*Rational(3, 2), S.Pi*Rational(8, 2))) \
is not S.EmptySet:
return AccumBounds(-1, Max(sin(min), sin(max)))
else:
return AccumBounds(Min(sin(min), sin(max)),
Max(sin(min), sin(max)))
elif isinstance(arg, SetExpr):
return arg._eval_func(cls)
if arg.could_extract_minus_sign():
return -cls(-arg)
i_coeff = arg.as_coefficient(S.ImaginaryUnit)
if i_coeff is not None:
return S.ImaginaryUnit*sinh(i_coeff)
pi_coeff = _pi_coeff(arg)
if pi_coeff is not None:
if pi_coeff.is_integer:
return S.Zero
if (2*pi_coeff).is_integer:
# is_even-case handled above as then pi_coeff.is_integer,
# so check if known to be not even
if pi_coeff.is_even is False:
return S.NegativeOne**(pi_coeff - S.Half)
if not pi_coeff.is_Rational:
narg = pi_coeff*S.Pi
if narg != arg:
return cls(narg)
return None
# https://github.com/sympy/sympy/issues/6048
# transform a sine to a cosine, to avoid redundant code
if pi_coeff.is_Rational:
x = pi_coeff % 2
if x > 1:
return -cls((x % 1)*S.Pi)
if 2*x > 1:
return cls((1 - x)*S.Pi)
narg = ((pi_coeff + Rational(3, 2)) % 2)*S.Pi
result = cos(narg)
if not isinstance(result, cos):
return result
if pi_coeff*S.Pi != arg:
return cls(pi_coeff*S.Pi)
return None
if arg.is_Add:
x, m = _peeloff_pi(arg)
if m:
return sin(m)*cos(x) + cos(m)*sin(x)
if arg.is_zero:
return S.Zero
if isinstance(arg, asin):
return arg.args[0]
if isinstance(arg, atan):
x = arg.args[0]
return x/sqrt(1 + x**2)
if isinstance(arg, atan2):
y, x = arg.args
return y/sqrt(x**2 + y**2)
if isinstance(arg, acos):
x = arg.args[0]
return sqrt(1 - x**2)
if isinstance(arg, acot):
x = arg.args[0]
return 1/(sqrt(1 + 1/x**2)*x)
if isinstance(arg, acsc):
x = arg.args[0]
return 1/x
if isinstance(arg, asec):
x = arg.args[0]
return sqrt(1 - 1/x**2)
@staticmethod
@cacheit
def taylor_term(n, x, *previous_terms):
if n < 0 or n % 2 == 0:
return S.Zero
else:
x = sympify(x)
if len(previous_terms) > 2:
p = previous_terms[-2]
return -p*x**2/(n*(n - 1))
else:
return (-1)**(n//2)*x**(n)/factorial(n)
def _eval_nseries(self, x, n, logx, cdir=0):
arg = self.args[0]
if logx is not None:
arg = arg.subs(log(x), logx)
if arg.subs(x, 0).has(S.NaN, S.ComplexInfinity):
raise PoleError("Cannot expand %s around 0" % (self))
return Function._eval_nseries(self, x, n=n, logx=logx, cdir=cdir)
def _eval_rewrite_as_exp(self, arg, **kwargs):
I = S.ImaginaryUnit
if isinstance(arg, TrigonometricFunction) or isinstance(arg, HyperbolicFunction):
arg = arg.func(arg.args[0]).rewrite(exp)
return (exp(arg*I) - exp(-arg*I))/(2*I)
def _eval_rewrite_as_Pow(self, arg, **kwargs):
if isinstance(arg, log):
I = S.ImaginaryUnit
x = arg.args[0]
return I*x**-I/2 - I*x**I /2
def _eval_rewrite_as_cos(self, arg, **kwargs):
return cos(arg - S.Pi/2, evaluate=False)
def _eval_rewrite_as_tan(self, arg, **kwargs):
tan_half = tan(S.Half*arg)
return 2*tan_half/(1 + tan_half**2)
def _eval_rewrite_as_sincos(self, arg, **kwargs):
return sin(arg)*cos(arg)/cos(arg)
def _eval_rewrite_as_cot(self, arg, **kwargs):
cot_half = cot(S.Half*arg)
return 2*cot_half/(1 + cot_half**2)
def _eval_rewrite_as_pow(self, arg, **kwargs):
return self.rewrite(cos).rewrite(pow)
def _eval_rewrite_as_sqrt(self, arg, **kwargs):
return self.rewrite(cos).rewrite(sqrt)
def _eval_rewrite_as_csc(self, arg, **kwargs):
return 1/csc(arg)
def _eval_rewrite_as_sec(self, arg, **kwargs):
return 1/sec(arg - S.Pi/2, evaluate=False)
def _eval_rewrite_as_sinc(self, arg, **kwargs):
return arg*sinc(arg)
def _eval_conjugate(self):
return self.func(self.args[0].conjugate())
def as_real_imag(self, deep=True, **hints):
re, im = self._as_real_imag(deep=deep, **hints)
return (sin(re)*cosh(im), cos(re)*sinh(im))
def _eval_expand_trig(self, **hints):
from sympy import expand_mul
from sympy.functions.special.polynomials import chebyshevt, chebyshevu
arg = self.args[0]
x = None
if arg.is_Add: # TODO, implement more if deep stuff here
# TODO: Do this more efficiently for more than two terms
x, y = arg.as_two_terms()
sx = sin(x, evaluate=False)._eval_expand_trig()
sy = sin(y, evaluate=False)._eval_expand_trig()
cx = cos(x, evaluate=False)._eval_expand_trig()
cy = cos(y, evaluate=False)._eval_expand_trig()
return sx*cy + sy*cx
elif arg.is_Mul:
n, x = arg.as_coeff_Mul(rational=True)
if n.is_Integer: # n will be positive because of .eval
# canonicalization
# See http://mathworld.wolfram.com/Multiple-AngleFormulas.html
if n.is_odd:
return (-1)**((n - 1)/2)*chebyshevt(n, sin(x))
else:
return expand_mul((-1)**(n/2 - 1)*cos(x)*chebyshevu(n -
1, sin(x)), deep=False)
pi_coeff = _pi_coeff(arg)
if pi_coeff is not None:
if pi_coeff.is_Rational:
return self.rewrite(sqrt)
return sin(arg)
def _eval_as_leading_term(self, x, logx=None, cdir=0):
from sympy import re
from sympy.calculus.util import AccumBounds
arg = self.args[0]
x0 = arg.subs(x, 0).cancel()
n = x0/S.Pi
if n.is_integer:
lt = (arg - n*S.Pi).as_leading_term(x)
return ((-1)**n)*lt
if x0 is S.ComplexInfinity:
x0 = arg.limit(x, 0, dir='-' if re(cdir).is_negative else '+')
if x0 in [S.Infinity, S.NegativeInfinity]:
return AccumBounds(-1, 1)
return self.func(x0) if x0.is_finite else self
def _eval_is_extended_real(self):
if self.args[0].is_extended_real:
return True
def _eval_is_finite(self):
arg = self.args[0]
if arg.is_extended_real:
return True
def _eval_is_zero(self):
arg = self.args[0]
if arg.is_zero:
return True
def _eval_is_complex(self):
if self.args[0].is_extended_real \
or self.args[0].is_complex:
return True
class cos(TrigonometricFunction):
"""
The cosine function.
Returns the cosine of x (measured in radians).
Explanation
===========
See :func:`sin` for notes about automatic evaluation.
Examples
========
>>> from sympy import cos, pi
>>> from sympy.abc import x
>>> cos(x**2).diff(x)
-2*x*sin(x**2)
>>> cos(1).diff(x)
0
>>> cos(pi)
-1
>>> cos(pi/2)
0
>>> cos(2*pi/3)
-1/2
>>> cos(pi/12)
sqrt(2)/4 + sqrt(6)/4
See Also
========
sin, csc, sec, tan, cot
asin, acsc, acos, asec, atan, acot, atan2
References
==========
.. [1] https://en.wikipedia.org/wiki/Trigonometric_functions
.. [2] http://dlmf.nist.gov/4.14
.. [3] http://functions.wolfram.com/ElementaryFunctions/Cos
"""
def period(self, symbol=None):
return self._period(2*pi, symbol)
def fdiff(self, argindex=1):
if argindex == 1:
return -sin(self.args[0])
else:
raise ArgumentIndexError(self, argindex)
@classmethod
def eval(cls, arg):
from sympy.functions.special.polynomials import chebyshevt
from sympy.calculus.util import AccumBounds
from sympy.sets.setexpr import SetExpr
if arg.is_Number:
if arg is S.NaN:
return S.NaN
elif arg.is_zero:
return S.One
elif arg is S.Infinity or arg is S.NegativeInfinity:
# In this case it is better to return AccumBounds(-1, 1)
# rather than returning S.NaN, since AccumBounds(-1, 1)
# preserves the information that sin(oo) is between
# -1 and 1, where S.NaN does not do that.
return AccumBounds(-1, 1)
if arg is S.ComplexInfinity:
return S.NaN
if isinstance(arg, AccumBounds):
return sin(arg + S.Pi/2)
elif isinstance(arg, SetExpr):
return arg._eval_func(cls)
if arg.is_extended_real and arg.is_finite is False:
return AccumBounds(-1, 1)
if arg.could_extract_minus_sign():
return cls(-arg)
i_coeff = arg.as_coefficient(S.ImaginaryUnit)
if i_coeff is not None:
return cosh(i_coeff)
pi_coeff = _pi_coeff(arg)
if pi_coeff is not None:
if pi_coeff.is_integer:
return (S.NegativeOne)**pi_coeff
if (2*pi_coeff).is_integer:
# is_even-case handled above as then pi_coeff.is_integer,
# so check if known to be not even
if pi_coeff.is_even is False:
return S.Zero
if not pi_coeff.is_Rational:
narg = pi_coeff*S.Pi
if narg != arg:
return cls(narg)
return None
# cosine formula #####################
# https://github.com/sympy/sympy/issues/6048
# explicit calculations are performed for
# cos(k pi/n) for n = 8,10,12,15,20,24,30,40,60,120
# Some other exact values like cos(k pi/240) can be
# calculated using a partial-fraction decomposition
# by calling cos( X ).rewrite(sqrt)
cst_table_some = {
3: S.Half,
5: (sqrt(5) + 1)/4,
}
if pi_coeff.is_Rational:
q = pi_coeff.q
p = pi_coeff.p % (2*q)
if p > q:
narg = (pi_coeff - 1)*S.Pi
return -cls(narg)
if 2*p > q:
narg = (1 - pi_coeff)*S.Pi
return -cls(narg)
# If nested sqrt's are worse than un-evaluation
# you can require q to be in (1, 2, 3, 4, 6, 12)
# q <= 12, q=15, q=20, q=24, q=30, q=40, q=60, q=120 return
# expressions with 2 or fewer sqrt nestings.
table2 = {
12: (3, 4),
20: (4, 5),
30: (5, 6),
15: (6, 10),
24: (6, 8),
40: (8, 10),
60: (20, 30),
120: (40, 60)
}
if q in table2:
a, b = p*S.Pi/table2[q][0], p*S.Pi/table2[q][1]
nvala, nvalb = cls(a), cls(b)
if None == nvala or None == nvalb:
return None
return nvala*nvalb + cls(S.Pi/2 - a)*cls(S.Pi/2 - b)
if q > 12:
return None
if q in cst_table_some:
cts = cst_table_some[pi_coeff.q]
return chebyshevt(pi_coeff.p, cts).expand()
if 0 == q % 2:
narg = (pi_coeff*2)*S.Pi
nval = cls(narg)
if None == nval:
return None
x = (2*pi_coeff + 1)/2
sign_cos = (-1)**((-1 if x < 0 else 1)*int(abs(x)))
return sign_cos*sqrt( (1 + nval)/2 )
return None
if arg.is_Add:
x, m = _peeloff_pi(arg)
if m:
return cos(m)*cos(x) - sin(m)*sin(x)
if arg.is_zero:
return S.One
if isinstance(arg, acos):
return arg.args[0]
if isinstance(arg, atan):
x = arg.args[0]
return 1/sqrt(1 + x**2)
if isinstance(arg, atan2):
y, x = arg.args
return x/sqrt(x**2 + y**2)
if isinstance(arg, asin):
x = arg.args[0]
return sqrt(1 - x ** 2)
if isinstance(arg, acot):
x = arg.args[0]
return 1/sqrt(1 + 1/x**2)
if isinstance(arg, acsc):
x = arg.args[0]
return sqrt(1 - 1/x**2)
if isinstance(arg, asec):
x = arg.args[0]
return 1/x
@staticmethod
@cacheit
def taylor_term(n, x, *previous_terms):
if n < 0 or n % 2 == 1:
return S.Zero
else:
x = sympify(x)
if len(previous_terms) > 2:
p = previous_terms[-2]
return -p*x**2/(n*(n - 1))
else:
return (-1)**(n//2)*x**(n)/factorial(n)
def _eval_nseries(self, x, n, logx, cdir=0):
arg = self.args[0]
if logx is not None:
arg = arg.subs(log(x), logx)
if arg.subs(x, 0).has(S.NaN, S.ComplexInfinity):
raise PoleError("Cannot expand %s around 0" % (self))
return Function._eval_nseries(self, x, n=n, logx=logx, cdir=cdir)
def _eval_rewrite_as_exp(self, arg, **kwargs):
I = S.ImaginaryUnit
if isinstance(arg, TrigonometricFunction) or isinstance(arg, HyperbolicFunction):
arg = arg.func(arg.args[0]).rewrite(exp)
return (exp(arg*I) + exp(-arg*I))/2
def _eval_rewrite_as_Pow(self, arg, **kwargs):
if isinstance(arg, log):
I = S.ImaginaryUnit
x = arg.args[0]
return x**I/2 + x**-I/2
def _eval_rewrite_as_sin(self, arg, **kwargs):
return sin(arg + S.Pi/2, evaluate=False)
def _eval_rewrite_as_tan(self, arg, **kwargs):
tan_half = tan(S.Half*arg)**2
return (1 - tan_half)/(1 + tan_half)
def _eval_rewrite_as_sincos(self, arg, **kwargs):
return sin(arg)*cos(arg)/sin(arg)
def _eval_rewrite_as_cot(self, arg, **kwargs):
cot_half = cot(S.Half*arg)**2
return (cot_half - 1)/(cot_half + 1)
def _eval_rewrite_as_pow(self, arg, **kwargs):
return self._eval_rewrite_as_sqrt(arg)
def _eval_rewrite_as_sqrt(self, arg, **kwargs):
from sympy.functions.special.polynomials import chebyshevt
def migcdex(x):
# recursive calcuation of gcd and linear combination
# for a sequence of integers.
# Given (x1, x2, x3)
# Returns (y1, y1, y3, g)
# such that g is the gcd and x1*y1+x2*y2+x3*y3 - g = 0
# Note, that this is only one such linear combination.
if len(x) == 1:
return (1, x[0])
if len(x) == 2:
return igcdex(x[0], x[-1])
g = migcdex(x[1:])
u, v, h = igcdex(x[0], g[-1])
return tuple([u] + [v*i for i in g[0:-1] ] + [h])
def ipartfrac(r, factors=None):
from sympy.ntheory import factorint
if isinstance(r, int):
return r
if not isinstance(r, Rational):
raise TypeError("r is not rational")
n = r.q
if 2 > r.q*r.q:
return r.q
if None == factors:
a = [n//x**y for x, y in factorint(r.q).items()]
else:
a = [n//x for x in factors]
if len(a) == 1:
return [ r ]
h = migcdex(a)
ans = [ r.p*Rational(i*j, r.q) for i, j in zip(h[:-1], a) ]
assert r == sum(ans)
return ans
pi_coeff = _pi_coeff(arg)
if pi_coeff is None:
return None
if pi_coeff.is_integer:
# it was unevaluated
return self.func(pi_coeff*S.Pi)
if not pi_coeff.is_Rational:
return None
def _cospi257():
""" Express cos(pi/257) explicitly as a function of radicals
Based upon the equations in
http://math.stackexchange.com/questions/516142/how-does-cos2-pi-257-look-like-in-real-radicals
See also http://www.susqu.edu/brakke/constructions/257-gon.m.txt
"""
def f1(a, b):
return (a + sqrt(a**2 + b))/2, (a - sqrt(a**2 + b))/2
def f2(a, b):
return (a - sqrt(a**2 + b))/2
t1, t2 = f1(-1, 256)
z1, z3 = f1(t1, 64)
z2, z4 = f1(t2, 64)
y1, y5 = f1(z1, 4*(5 + t1 + 2*z1))
y6, y2 = f1(z2, 4*(5 + t2 + 2*z2))
y3, y7 = f1(z3, 4*(5 + t1 + 2*z3))
y8, y4 = f1(z4, 4*(5 + t2 + 2*z4))
x1, x9 = f1(y1, -4*(t1 + y1 + y3 + 2*y6))
x2, x10 = f1(y2, -4*(t2 + y2 + y4 + 2*y7))
x3, x11 = f1(y3, -4*(t1 + y3 + y5 + 2*y8))
x4, x12 = f1(y4, -4*(t2 + y4 + y6 + 2*y1))
x5, x13 = f1(y5, -4*(t1 + y5 + y7 + 2*y2))
x6, x14 = f1(y6, -4*(t2 + y6 + y8 + 2*y3))
x15, x7 = f1(y7, -4*(t1 + y7 + y1 + 2*y4))
x8, x16 = f1(y8, -4*(t2 + y8 + y2 + 2*y5))
v1 = f2(x1, -4*(x1 + x2 + x3 + x6))
v2 = f2(x2, -4*(x2 + x3 + x4 + x7))
v3 = f2(x8, -4*(x8 + x9 + x10 + x13))
v4 = f2(x9, -4*(x9 + x10 + x11 + x14))
v5 = f2(x10, -4*(x10 + x11 + x12 + x15))
v6 = f2(x16, -4*(x16 + x1 + x2 + x5))
u1 = -f2(-v1, -4*(v2 + v3))
u2 = -f2(-v4, -4*(v5 + v6))
w1 = -2*f2(-u1, -4*u2)
return sqrt(sqrt(2)*sqrt(w1 + 4)/8 + S.Half)
cst_table_some = {
3: S.Half,
5: (sqrt(5) + 1)/4,
17: sqrt((15 + sqrt(17))/32 + sqrt(2)*(sqrt(17 - sqrt(17)) +
sqrt(sqrt(2)*(-8*sqrt(17 + sqrt(17)) - (1 - sqrt(17))
*sqrt(17 - sqrt(17))) + 6*sqrt(17) + 34))/32),
257: _cospi257()
# 65537 is the only other known Fermat prime and the very
# large expression is intentionally omitted from SymPy; see
# http://www.susqu.edu/brakke/constructions/65537-gon.m.txt
}
def _fermatCoords(n):
# if n can be factored in terms of Fermat primes with
# multiplicity of each being 1, return those primes, else
# False
primes = []
for p_i in cst_table_some:
quotient, remainder = divmod(n, p_i)
if remainder == 0:
n = quotient
primes.append(p_i)
if n == 1:
return tuple(primes)
return False
if pi_coeff.q in cst_table_some:
rv = chebyshevt(pi_coeff.p, cst_table_some[pi_coeff.q])
if pi_coeff.q < 257:
rv = rv.expand()
return rv
if not pi_coeff.q % 2: # recursively remove factors of 2
pico2 = pi_coeff*2
nval = cos(pico2*S.Pi).rewrite(sqrt)
x = (pico2 + 1)/2
sign_cos = -1 if int(x) % 2 else 1
return sign_cos*sqrt( (1 + nval)/2 )
FC = _fermatCoords(pi_coeff.q)
if FC:
decomp = ipartfrac(pi_coeff, FC)
X = [(x[1], x[0]*S.Pi) for x in zip(decomp, numbered_symbols('z'))]
pcls = cos(sum([x[0] for x in X]))._eval_expand_trig().subs(X)
return pcls.rewrite(sqrt)
else:
decomp = ipartfrac(pi_coeff)
X = [(x[1], x[0]*S.Pi) for x in zip(decomp, numbered_symbols('z'))]
pcls = cos(sum([x[0] for x in X]))._eval_expand_trig().subs(X)
return pcls
def _eval_rewrite_as_sec(self, arg, **kwargs):
return 1/sec(arg)
def _eval_rewrite_as_csc(self, arg, **kwargs):
return 1/sec(arg).rewrite(csc)
def _eval_conjugate(self):
return self.func(self.args[0].conjugate())
def as_real_imag(self, deep=True, **hints):
re, im = self._as_real_imag(deep=deep, **hints)
return (cos(re)*cosh(im), -sin(re)*sinh(im))
def _eval_expand_trig(self, **hints):
from sympy.functions.special.polynomials import chebyshevt
arg = self.args[0]
x = None
if arg.is_Add: # TODO: Do this more efficiently for more than two terms
x, y = arg.as_two_terms()
sx = sin(x, evaluate=False)._eval_expand_trig()
sy = sin(y, evaluate=False)._eval_expand_trig()
cx = cos(x, evaluate=False)._eval_expand_trig()
cy = cos(y, evaluate=False)._eval_expand_trig()
return cx*cy - sx*sy
elif arg.is_Mul:
coeff, terms = arg.as_coeff_Mul(rational=True)
if coeff.is_Integer:
return chebyshevt(coeff, cos(terms))
pi_coeff = _pi_coeff(arg)
if pi_coeff is not None:
if pi_coeff.is_Rational:
return self.rewrite(sqrt)
return cos(arg)
def _eval_as_leading_term(self, x, logx=None, cdir=0):
from sympy import re
from sympy.calculus.util import AccumBounds
arg = self.args[0]
x0 = arg.subs(x, 0).cancel()
n = (x0 + S.Pi/2)/S.Pi
if n.is_integer:
lt = (arg - n*S.Pi + S.Pi/2).as_leading_term(x)
return ((-1)**n)*lt
if x0 is S.ComplexInfinity:
x0 = arg.limit(x, 0, dir='-' if re(cdir).is_negative else '+')
if x0 in [S.Infinity, S.NegativeInfinity]:
return AccumBounds(-1, 1)
return self.func(x0) if x0.is_finite else self
def _eval_is_extended_real(self):
if self.args[0].is_extended_real:
return True
def _eval_is_finite(self):
arg = self.args[0]
if arg.is_extended_real:
return True
def _eval_is_complex(self):
if self.args[0].is_extended_real \
or self.args[0].is_complex:
return True
class tan(TrigonometricFunction):
"""
The tangent function.
Returns the tangent of x (measured in radians).
Explanation
===========
See :func:`sin` for notes about automatic evaluation.
Examples
========
>>> from sympy import tan, pi
>>> from sympy.abc import x
>>> tan(x**2).diff(x)
2*x*(tan(x**2)**2 + 1)
>>> tan(1).diff(x)
0
>>> tan(pi/8).expand()
-1 + sqrt(2)
See Also
========
sin, csc, cos, sec, cot
asin, acsc, acos, asec, atan, acot, atan2
References
==========
.. [1] https://en.wikipedia.org/wiki/Trigonometric_functions
.. [2] http://dlmf.nist.gov/4.14
.. [3] http://functions.wolfram.com/ElementaryFunctions/Tan
"""
def period(self, symbol=None):
return self._period(pi, symbol)
def fdiff(self, argindex=1):
if argindex == 1:
return S.One + self**2
else:
raise ArgumentIndexError(self, argindex)
def inverse(self, argindex=1):
"""
Returns the inverse of this function.
"""
return atan
@classmethod
def eval(cls, arg):
from sympy.calculus.util import AccumBounds
if arg.is_Number:
if arg is S.NaN:
return S.NaN
elif arg.is_zero:
return S.Zero
elif arg is S.Infinity or arg is S.NegativeInfinity:
return AccumBounds(S.NegativeInfinity, S.Infinity)
if arg is S.ComplexInfinity:
return S.NaN
if isinstance(arg, AccumBounds):
min, max = arg.min, arg.max
d = floor(min/S.Pi)
if min is not S.NegativeInfinity:
min = min - d*S.Pi
if max is not S.Infinity:
max = max - d*S.Pi
if AccumBounds(min, max).intersection(FiniteSet(S.Pi/2, S.Pi*Rational(3, 2))):
return AccumBounds(S.NegativeInfinity, S.Infinity)
else:
return AccumBounds(tan(min), tan(max))
if arg.could_extract_minus_sign():
return -cls(-arg)
i_coeff = arg.as_coefficient(S.ImaginaryUnit)
if i_coeff is not None:
return S.ImaginaryUnit*tanh(i_coeff)
pi_coeff = _pi_coeff(arg, 2)
if pi_coeff is not None:
if pi_coeff.is_integer:
return S.Zero
if not pi_coeff.is_Rational:
narg = pi_coeff*S.Pi
if narg != arg:
return cls(narg)
return None
if pi_coeff.is_Rational:
q = pi_coeff.q
p = pi_coeff.p % q
# ensure simplified results are returned for n*pi/5, n*pi/10
table10 = {
1: sqrt(1 - 2*sqrt(5)/5),
2: sqrt(5 - 2*sqrt(5)),
3: sqrt(1 + 2*sqrt(5)/5),
4: sqrt(5 + 2*sqrt(5))
}
if q == 5 or q == 10:
n = 10*p/q
if n > 5:
n = 10 - n
return -table10[n]
else:
return table10[n]
if not pi_coeff.q % 2:
narg = pi_coeff*S.Pi*2
cresult, sresult = cos(narg), cos(narg - S.Pi/2)
if not isinstance(cresult, cos) \
and not isinstance(sresult, cos):
if sresult == 0:
return S.ComplexInfinity
return 1/sresult - cresult/sresult
table2 = {
12: (3, 4),
20: (4, 5),
30: (5, 6),
15: (6, 10),
24: (6, 8),
40: (8, 10),
60: (20, 30),
120: (40, 60)
}
if q in table2:
nvala, nvalb = cls(p*S.Pi/table2[q][0]), cls(p*S.Pi/table2[q][1])
if None == nvala or None == nvalb:
return None
return (nvala - nvalb)/(1 + nvala*nvalb)
narg = ((pi_coeff + S.Half) % 1 - S.Half)*S.Pi
# see cos() to specify which expressions should be
# expanded automatically in terms of radicals
cresult, sresult = cos(narg), cos(narg - S.Pi/2)
if not isinstance(cresult, cos) \
and not isinstance(sresult, cos):
if cresult == 0:
return S.ComplexInfinity
return (sresult/cresult)
if narg != arg:
return cls(narg)
if arg.is_Add:
x, m = _peeloff_pi(arg)
if m:
tanm = tan(m)
if tanm is S.ComplexInfinity:
return -cot(x)
else: # tanm == 0
return tan(x)
if arg.is_zero:
return S.Zero
if isinstance(arg, atan):
return arg.args[0]
if isinstance(arg, atan2):
y, x = arg.args
return y/x
if isinstance(arg, asin):
x = arg.args[0]
return x/sqrt(1 - x**2)
if isinstance(arg, acos):
x = arg.args[0]
return sqrt(1 - x**2)/x
if isinstance(arg, acot):
x = arg.args[0]
return 1/x
if isinstance(arg, acsc):
x = arg.args[0]
return 1/(sqrt(1 - 1/x**2)*x)
if isinstance(arg, asec):
x = arg.args[0]
return sqrt(1 - 1/x**2)*x
@staticmethod
@cacheit
def taylor_term(n, x, *previous_terms):
from sympy import bernoulli
if n < 0 or n % 2 == 0:
return S.Zero
else:
x = sympify(x)
a, b = ((n - 1)//2), 2**(n + 1)
B = bernoulli(n + 1)
F = factorial(n + 1)
return (-1)**a*b*(b - 1)*B/F*x**n
def _eval_nseries(self, x, n, logx, cdir=0):
i = self.args[0].limit(x, 0)*2/S.Pi
if i and i.is_Integer:
return self.rewrite(cos)._eval_nseries(x, n=n, logx=logx)
return Function._eval_nseries(self, x, n=n, logx=logx)
def _eval_rewrite_as_Pow(self, arg, **kwargs):
if isinstance(arg, log):
I = S.ImaginaryUnit
x = arg.args[0]
return I*(x**-I - x**I)/(x**-I + x**I)
def _eval_conjugate(self):
return self.func(self.args[0].conjugate())
def as_real_imag(self, deep=True, **hints):
re, im = self._as_real_imag(deep=deep, **hints)
if im:
denom = cos(2*re) + cosh(2*im)
return (sin(2*re)/denom, sinh(2*im)/denom)
else:
return (self.func(re), S.Zero)
def _eval_expand_trig(self, **hints):
from sympy import im, re
arg = self.args[0]
x = None
if arg.is_Add:
from sympy import symmetric_poly
n = len(arg.args)
TX = []
for x in arg.args:
tx = tan(x, evaluate=False)._eval_expand_trig()
TX.append(tx)
Yg = numbered_symbols('Y')
Y = [ next(Yg) for i in range(n) ]
p = [0, 0]
for i in range(n + 1):
p[1 - i % 2] += symmetric_poly(i, Y)*(-1)**((i % 4)//2)
return (p[0]/p[1]).subs(list(zip(Y, TX)))
elif arg.is_Mul:
coeff, terms = arg.as_coeff_Mul(rational=True)
if coeff.is_Integer and coeff > 1:
I = S.ImaginaryUnit
z = Symbol('dummy', real=True)
P = ((1 + I*z)**coeff).expand()
return (im(P)/re(P)).subs([(z, tan(terms))])
return tan(arg)
def _eval_rewrite_as_exp(self, arg, **kwargs):
I = S.ImaginaryUnit
if isinstance(arg, TrigonometricFunction) or isinstance(arg, HyperbolicFunction):
arg = arg.func(arg.args[0]).rewrite(exp)
neg_exp, pos_exp = exp(-arg*I), exp(arg*I)
return I*(neg_exp - pos_exp)/(neg_exp + pos_exp)
def _eval_rewrite_as_sin(self, x, **kwargs):
return 2*sin(x)**2/sin(2*x)
def _eval_rewrite_as_cos(self, x, **kwargs):
return cos(x - S.Pi/2, evaluate=False)/cos(x)
def _eval_rewrite_as_sincos(self, arg, **kwargs):
return sin(arg)/cos(arg)
def _eval_rewrite_as_cot(self, arg, **kwargs):
return 1/cot(arg)
def _eval_rewrite_as_sec(self, arg, **kwargs):
sin_in_sec_form = sin(arg).rewrite(sec)
cos_in_sec_form = cos(arg).rewrite(sec)
return sin_in_sec_form/cos_in_sec_form
def _eval_rewrite_as_csc(self, arg, **kwargs):
sin_in_csc_form = sin(arg).rewrite(csc)
cos_in_csc_form = cos(arg).rewrite(csc)
return sin_in_csc_form/cos_in_csc_form
def _eval_rewrite_as_pow(self, arg, **kwargs):
y = self.rewrite(cos).rewrite(pow)
if y.has(cos):
return None
return y
def _eval_rewrite_as_sqrt(self, arg, **kwargs):
y = self.rewrite(cos).rewrite(sqrt)
if y.has(cos):
return None
return y
def _eval_as_leading_term(self, x, logx=None, cdir=0):
arg = self.args[0]
x0 = arg.subs(x, 0).cancel()
n = 2*x0/S.Pi
if n.is_integer:
lt = (arg - n*S.Pi/2).as_leading_term(x)
return lt if n.is_even else -1/lt
return self.func(x0) if x0.is_finite else self
def _eval_is_extended_real(self):
# FIXME: currently tan(pi/2) return zoo
return self.args[0].is_extended_real
def _eval_is_real(self):
arg = self.args[0]
if arg.is_real and (arg/pi - S.Half).is_integer is False:
return True
def _eval_is_finite(self):
arg = self.args[0]
if arg.is_real and (arg/pi - S.Half).is_integer is False:
return True
if arg.is_imaginary:
return True
def _eval_is_zero(self):
arg = self.args[0]
if arg.is_zero:
return True
def _eval_is_complex(self):
arg = self.args[0]
if arg.is_real and (arg/pi - S.Half).is_integer is False:
return True
class cot(TrigonometricFunction):
"""
The cotangent function.
Returns the cotangent of x (measured in radians).
Explanation
===========
See :func:`sin` for notes about automatic evaluation.
Examples
========
>>> from sympy import cot, pi
>>> from sympy.abc import x
>>> cot(x**2).diff(x)
2*x*(-cot(x**2)**2 - 1)
>>> cot(1).diff(x)
0
>>> cot(pi/12)
sqrt(3) + 2
See Also
========
sin, csc, cos, sec, tan
asin, acsc, acos, asec, atan, acot, atan2
References
==========
.. [1] https://en.wikipedia.org/wiki/Trigonometric_functions
.. [2] http://dlmf.nist.gov/4.14
.. [3] http://functions.wolfram.com/ElementaryFunctions/Cot
"""
def period(self, symbol=None):
return self._period(pi, symbol)
def fdiff(self, argindex=1):
if argindex == 1:
return S.NegativeOne - self**2
else:
raise ArgumentIndexError(self, argindex)
def inverse(self, argindex=1):
"""
Returns the inverse of this function.
"""
return acot
@classmethod
def eval(cls, arg):
from sympy.calculus.util import AccumBounds
if arg.is_Number:
if arg is S.NaN:
return S.NaN
if arg.is_zero:
return S.ComplexInfinity
if arg is S.ComplexInfinity:
return S.NaN
if isinstance(arg, AccumBounds):
return -tan(arg + S.Pi/2)
if arg.could_extract_minus_sign():
return -cls(-arg)
i_coeff = arg.as_coefficient(S.ImaginaryUnit)
if i_coeff is not None:
return -S.ImaginaryUnit*coth(i_coeff)
pi_coeff = _pi_coeff(arg, 2)
if pi_coeff is not None:
if pi_coeff.is_integer:
return S.ComplexInfinity
if not pi_coeff.is_Rational:
narg = pi_coeff*S.Pi
if narg != arg:
return cls(narg)
return None
if pi_coeff.is_Rational:
if pi_coeff.q == 5 or pi_coeff.q == 10:
return tan(S.Pi/2 - arg)
if pi_coeff.q > 2 and not pi_coeff.q % 2:
narg = pi_coeff*S.Pi*2
cresult, sresult = cos(narg), cos(narg - S.Pi/2)
if not isinstance(cresult, cos) \
and not isinstance(sresult, cos):
return 1/sresult + cresult/sresult
table2 = {
12: (3, 4),
20: (4, 5),
30: (5, 6),
15: (6, 10),
24: (6, 8),
40: (8, 10),
60: (20, 30),
120: (40, 60)
}
q = pi_coeff.q
p = pi_coeff.p % q
if q in table2:
nvala, nvalb = cls(p*S.Pi/table2[q][0]), cls(p*S.Pi/table2[q][1])
if None == nvala or None == nvalb:
return None
return (1 + nvala*nvalb)/(nvalb - nvala)
narg = (((pi_coeff + S.Half) % 1) - S.Half)*S.Pi
# see cos() to specify which expressions should be
# expanded automatically in terms of radicals
cresult, sresult = cos(narg), cos(narg - S.Pi/2)
if not isinstance(cresult, cos) \
and not isinstance(sresult, cos):
if sresult == 0:
return S.ComplexInfinity
return cresult/sresult
if narg != arg:
return cls(narg)
if arg.is_Add:
x, m = _peeloff_pi(arg)
if m:
cotm = cot(m)
if cotm is S.ComplexInfinity:
return cot(x)
else: # cotm == 0
return -tan(x)
if arg.is_zero:
return S.ComplexInfinity
if isinstance(arg, acot):
return arg.args[0]
if isinstance(arg, atan):
x = arg.args[0]
return 1/x
if isinstance(arg, atan2):
y, x = arg.args
return x/y
if isinstance(arg, asin):
x = arg.args[0]
return sqrt(1 - x**2)/x
if isinstance(arg, acos):
x = arg.args[0]
return x/sqrt(1 - x**2)
if isinstance(arg, acsc):
x = arg.args[0]
return sqrt(1 - 1/x**2)*x
if isinstance(arg, asec):
x = arg.args[0]
return 1/(sqrt(1 - 1/x**2)*x)
@staticmethod
@cacheit
def taylor_term(n, x, *previous_terms):
from sympy import bernoulli
if n == 0:
return 1/sympify(x)
elif n < 0 or n % 2 == 0:
return S.Zero
else:
x = sympify(x)
B = bernoulli(n + 1)
F = factorial(n + 1)
return (-1)**((n + 1)//2)*2**(n + 1)*B/F*x**n
def _eval_nseries(self, x, n, logx, cdir=0):
i = self.args[0].limit(x, 0)/S.Pi
if i and i.is_Integer:
return self.rewrite(cos)._eval_nseries(x, n=n, logx=logx)
return self.rewrite(tan)._eval_nseries(x, n=n, logx=logx)
def _eval_conjugate(self):
return self.func(self.args[0].conjugate())
def as_real_imag(self, deep=True, **hints):
re, im = self._as_real_imag(deep=deep, **hints)
if im:
denom = cos(2*re) - cosh(2*im)
return (-sin(2*re)/denom, sinh(2*im)/denom)
else:
return (self.func(re), S.Zero)
def _eval_rewrite_as_exp(self, arg, **kwargs):
I = S.ImaginaryUnit
if isinstance(arg, TrigonometricFunction) or isinstance(arg, HyperbolicFunction):
arg = arg.func(arg.args[0]).rewrite(exp)
neg_exp, pos_exp = exp(-arg*I), exp(arg*I)
return I*(pos_exp + neg_exp)/(pos_exp - neg_exp)
def _eval_rewrite_as_Pow(self, arg, **kwargs):
if isinstance(arg, log):
I = S.ImaginaryUnit
x = arg.args[0]
return -I*(x**-I + x**I)/(x**-I - x**I)
def _eval_rewrite_as_sin(self, x, **kwargs):
return sin(2*x)/(2*(sin(x)**2))
def _eval_rewrite_as_cos(self, x, **kwargs):
return cos(x)/cos(x - S.Pi/2, evaluate=False)
def _eval_rewrite_as_sincos(self, arg, **kwargs):
return cos(arg)/sin(arg)
def _eval_rewrite_as_tan(self, arg, **kwargs):
return 1/tan(arg)
def _eval_rewrite_as_sec(self, arg, **kwargs):
cos_in_sec_form = cos(arg).rewrite(sec)
sin_in_sec_form = sin(arg).rewrite(sec)
return cos_in_sec_form/sin_in_sec_form
def _eval_rewrite_as_csc(self, arg, **kwargs):
cos_in_csc_form = cos(arg).rewrite(csc)
sin_in_csc_form = sin(arg).rewrite(csc)
return cos_in_csc_form/sin_in_csc_form
def _eval_rewrite_as_pow(self, arg, **kwargs):
y = self.rewrite(cos).rewrite(pow)
if y.has(cos):
return None
return y
def _eval_rewrite_as_sqrt(self, arg, **kwargs):
y = self.rewrite(cos).rewrite(sqrt)
if y.has(cos):
return None
return y
def _eval_as_leading_term(self, x, logx=None, cdir=0):
arg = self.args[0]
x0 = arg.subs(x, 0).cancel()
n = 2*x0/S.Pi
if n.is_integer:
lt = (arg - n*S.Pi/2).as_leading_term(x)
return 1/lt if n.is_even else -lt
return self.func(x0) if x0.is_finite else self
def _eval_is_extended_real(self):
return self.args[0].is_extended_real
def _eval_expand_trig(self, **hints):
from sympy import im, re
arg = self.args[0]
x = None
if arg.is_Add:
from sympy import symmetric_poly
n = len(arg.args)
CX = []
for x in arg.args:
cx = cot(x, evaluate=False)._eval_expand_trig()
CX.append(cx)
Yg = numbered_symbols('Y')
Y = [ next(Yg) for i in range(n) ]
p = [0, 0]
for i in range(n, -1, -1):
p[(n - i) % 2] += symmetric_poly(i, Y)*(-1)**(((n - i) % 4)//2)
return (p[0]/p[1]).subs(list(zip(Y, CX)))
elif arg.is_Mul:
coeff, terms = arg.as_coeff_Mul(rational=True)
if coeff.is_Integer and coeff > 1:
I = S.ImaginaryUnit
z = Symbol('dummy', real=True)
P = ((z + I)**coeff).expand()
return (re(P)/im(P)).subs([(z, cot(terms))])
return cot(arg) # XXX sec and csc return 1/cos and 1/sin
def _eval_is_finite(self):
arg = self.args[0]
if arg.is_real and (arg/pi).is_integer is False:
return True
if arg.is_imaginary:
return True
def _eval_is_real(self):
arg = self.args[0]
if arg.is_real and (arg/pi).is_integer is False:
return True
def _eval_is_complex(self):
arg = self.args[0]
if arg.is_real and (arg/pi).is_integer is False:
return True
def _eval_subs(self, old, new):
arg = self.args[0]
argnew = arg.subs(old, new)
if arg != argnew and (argnew/S.Pi).is_integer:
return S.ComplexInfinity
return cot(argnew)
class ReciprocalTrigonometricFunction(TrigonometricFunction):
"""Base class for reciprocal functions of trigonometric functions. """
_reciprocal_of = None # mandatory, to be defined in subclass
_singularities = (S.ComplexInfinity,)
# _is_even and _is_odd are used for correct evaluation of csc(-x), sec(-x)
# TODO refactor into TrigonometricFunction common parts of
# trigonometric functions eval() like even/odd, func(x+2*k*pi), etc.
# optional, to be defined in subclasses:
_is_even = None # type: FuzzyBool
_is_odd = None # type: FuzzyBool
@classmethod
def eval(cls, arg):
if arg.could_extract_minus_sign():
if cls._is_even:
return cls(-arg)
if cls._is_odd:
return -cls(-arg)
pi_coeff = _pi_coeff(arg)
if (pi_coeff is not None
and not (2*pi_coeff).is_integer
and pi_coeff.is_Rational):
q = pi_coeff.q
p = pi_coeff.p % (2*q)
if p > q:
narg = (pi_coeff - 1)*S.Pi
return -cls(narg)
if 2*p > q:
narg = (1 - pi_coeff)*S.Pi
if cls._is_odd:
return cls(narg)
elif cls._is_even:
return -cls(narg)
if hasattr(arg, 'inverse') and arg.inverse() == cls:
return arg.args[0]
t = cls._reciprocal_of.eval(arg)
if t is None:
return t
elif any(isinstance(i, cos) for i in (t, -t)):
return (1/t).rewrite(sec)
elif any(isinstance(i, sin) for i in (t, -t)):
return (1/t).rewrite(csc)
else:
return 1/t
def _call_reciprocal(self, method_name, *args, **kwargs):
# Calls method_name on _reciprocal_of
o = self._reciprocal_of(self.args[0])
return getattr(o, method_name)(*args, **kwargs)
def _calculate_reciprocal(self, method_name, *args, **kwargs):
# If calling method_name on _reciprocal_of returns a value != None
# then return the reciprocal of that value
t = self._call_reciprocal(method_name, *args, **kwargs)
return 1/t if t is not None else t
def _rewrite_reciprocal(self, method_name, arg):
# Special handling for rewrite functions. If reciprocal rewrite returns
# unmodified expression, then return None
t = self._call_reciprocal(method_name, arg)
if t is not None and t != self._reciprocal_of(arg):
return 1/t
def _period(self, symbol):
f = expand_mul(self.args[0])
return self._reciprocal_of(f).period(symbol)
def fdiff(self, argindex=1):
return -self._calculate_reciprocal("fdiff", argindex)/self**2
def _eval_rewrite_as_exp(self, arg, **kwargs):
return self._rewrite_reciprocal("_eval_rewrite_as_exp", arg)
def _eval_rewrite_as_Pow(self, arg, **kwargs):
return self._rewrite_reciprocal("_eval_rewrite_as_Pow", arg)
def _eval_rewrite_as_sin(self, arg, **kwargs):
return self._rewrite_reciprocal("_eval_rewrite_as_sin", arg)
def _eval_rewrite_as_cos(self, arg, **kwargs):
return self._rewrite_reciprocal("_eval_rewrite_as_cos", arg)
def _eval_rewrite_as_tan(self, arg, **kwargs):
return self._rewrite_reciprocal("_eval_rewrite_as_tan", arg)
def _eval_rewrite_as_pow(self, arg, **kwargs):
return self._rewrite_reciprocal("_eval_rewrite_as_pow", arg)
def _eval_rewrite_as_sqrt(self, arg, **kwargs):
return self._rewrite_reciprocal("_eval_rewrite_as_sqrt", arg)
def _eval_conjugate(self):
return self.func(self.args[0].conjugate())
def as_real_imag(self, deep=True, **hints):
return (1/self._reciprocal_of(self.args[0])).as_real_imag(deep,
**hints)
def _eval_expand_trig(self, **hints):
return self._calculate_reciprocal("_eval_expand_trig", **hints)
def _eval_is_extended_real(self):
return self._reciprocal_of(self.args[0])._eval_is_extended_real()
def _eval_as_leading_term(self, x, logx=None, cdir=0):
return (1/self._reciprocal_of(self.args[0]))._eval_as_leading_term(x)
def _eval_is_finite(self):
return (1/self._reciprocal_of(self.args[0])).is_finite
def _eval_nseries(self, x, n, logx, cdir=0):
return (1/self._reciprocal_of(self.args[0]))._eval_nseries(x, n, logx)
class sec(ReciprocalTrigonometricFunction):
"""
The secant function.
Returns the secant of x (measured in radians).
Explanation
===========
See :func:`sin` for notes about automatic evaluation.
Examples
========
>>> from sympy import sec
>>> from sympy.abc import x
>>> sec(x**2).diff(x)
2*x*tan(x**2)*sec(x**2)
>>> sec(1).diff(x)
0
See Also
========
sin, csc, cos, tan, cot
asin, acsc, acos, asec, atan, acot, atan2
References
==========
.. [1] https://en.wikipedia.org/wiki/Trigonometric_functions
.. [2] http://dlmf.nist.gov/4.14
.. [3] http://functions.wolfram.com/ElementaryFunctions/Sec
"""
_reciprocal_of = cos
_is_even = True
def period(self, symbol=None):
return self._period(symbol)
def _eval_rewrite_as_cot(self, arg, **kwargs):
cot_half_sq = cot(arg/2)**2
return (cot_half_sq + 1)/(cot_half_sq - 1)
def _eval_rewrite_as_cos(self, arg, **kwargs):
return (1/cos(arg))
def _eval_rewrite_as_sincos(self, arg, **kwargs):
return sin(arg)/(cos(arg)*sin(arg))
def _eval_rewrite_as_sin(self, arg, **kwargs):
return (1/cos(arg).rewrite(sin))
def _eval_rewrite_as_tan(self, arg, **kwargs):
return (1/cos(arg).rewrite(tan))
def _eval_rewrite_as_csc(self, arg, **kwargs):
return csc(pi/2 - arg, evaluate=False)
def fdiff(self, argindex=1):
if argindex == 1:
return tan(self.args[0])*sec(self.args[0])
else:
raise ArgumentIndexError(self, argindex)
def _eval_is_complex(self):
arg = self.args[0]
if arg.is_complex and (arg/pi - S.Half).is_integer is False:
return True
@staticmethod
@cacheit
def taylor_term(n, x, *previous_terms):
# Reference Formula:
# http://functions.wolfram.com/ElementaryFunctions/Sec/06/01/02/01/
from sympy.functions.combinatorial.numbers import euler
if n < 0 or n % 2 == 1:
return S.Zero
else:
x = sympify(x)
k = n//2
return (-1)**k*euler(2*k)/factorial(2*k)*x**(2*k)
def _eval_as_leading_term(self, x, logx=None, cdir=0):
arg = self.args[0]
x0 = arg.subs(x, 0).cancel()
n = (x0 + S.Pi/2)/S.Pi
if n.is_integer:
lt = (arg - n*S.Pi + S.Pi/2).as_leading_term(x)
return ((-1)**n)/lt
return self.func(x0)
class csc(ReciprocalTrigonometricFunction):
"""
The cosecant function.
Returns the cosecant of x (measured in radians).
Explanation
===========
See :func:`sin` for notes about automatic evaluation.
Examples
========
>>> from sympy import csc
>>> from sympy.abc import x
>>> csc(x**2).diff(x)
-2*x*cot(x**2)*csc(x**2)
>>> csc(1).diff(x)
0
See Also
========
sin, cos, sec, tan, cot
asin, acsc, acos, asec, atan, acot, atan2
References
==========
.. [1] https://en.wikipedia.org/wiki/Trigonometric_functions
.. [2] http://dlmf.nist.gov/4.14
.. [3] http://functions.wolfram.com/ElementaryFunctions/Csc
"""
_reciprocal_of = sin
_is_odd = True
def period(self, symbol=None):
return self._period(symbol)
def _eval_rewrite_as_sin(self, arg, **kwargs):
return (1/sin(arg))
def _eval_rewrite_as_sincos(self, arg, **kwargs):
return cos(arg)/(sin(arg)*cos(arg))
def _eval_rewrite_as_cot(self, arg, **kwargs):
cot_half = cot(arg/2)
return (1 + cot_half**2)/(2*cot_half)
def _eval_rewrite_as_cos(self, arg, **kwargs):
return 1/sin(arg).rewrite(cos)
def _eval_rewrite_as_sec(self, arg, **kwargs):
return sec(pi/2 - arg, evaluate=False)
def _eval_rewrite_as_tan(self, arg, **kwargs):
return (1/sin(arg).rewrite(tan))
def fdiff(self, argindex=1):
if argindex == 1:
return -cot(self.args[0])*csc(self.args[0])
else:
raise ArgumentIndexError(self, argindex)
def _eval_is_complex(self):
arg = self.args[0]
if arg.is_real and (arg/pi).is_integer is False:
return True
@staticmethod
@cacheit
def taylor_term(n, x, *previous_terms):
from sympy import bernoulli
if n == 0:
return 1/sympify(x)
elif n < 0 or n % 2 == 0:
return S.Zero
else:
x = sympify(x)
k = n//2 + 1
return ((-1)**(k - 1)*2*(2**(2*k - 1) - 1)*
bernoulli(2*k)*x**(2*k - 1)/factorial(2*k))
class sinc(Function):
r"""
Represents an unnormalized sinc function:
.. math::
\operatorname{sinc}(x) =
\begin{cases}
\frac{\sin x}{x} & \qquad x \neq 0 \\
1 & \qquad x = 0
\end{cases}
Examples
========
>>> from sympy import sinc, oo, jn
>>> from sympy.abc import x
>>> sinc(x)
sinc(x)
* Automated Evaluation
>>> sinc(0)
1
>>> sinc(oo)
0
* Differentiation
>>> sinc(x).diff()
cos(x)/x - sin(x)/x**2
* Series Expansion
>>> sinc(x).series()
1 - x**2/6 + x**4/120 + O(x**6)
* As zero'th order spherical Bessel Function
>>> sinc(x).rewrite(jn)
jn(0, x)
See also
========
sin
References
==========
.. [1] https://en.wikipedia.org/wiki/Sinc_function
"""
_singularities = (S.ComplexInfinity,)
def fdiff(self, argindex=1):
x = self.args[0]
if argindex == 1:
# We would like to return the Piecewise here, but Piecewise.diff
# currently can't handle removable singularities, meaning things
# like sinc(x).diff(x, 2) give the wrong answer at x = 0. See
# https://github.com/sympy/sympy/issues/11402.
#
# return Piecewise(((x*cos(x) - sin(x))/x**2, Ne(x, S.Zero)), (S.Zero, S.true))
return cos(x)/x - sin(x)/x**2
else:
raise ArgumentIndexError(self, argindex)
@classmethod
def eval(cls, arg):
if arg.is_zero:
return S.One
if arg.is_Number:
if arg in [S.Infinity, S.NegativeInfinity]:
return S.Zero
elif arg is S.NaN:
return S.NaN
if arg is S.ComplexInfinity:
return S.NaN
if arg.could_extract_minus_sign():
return cls(-arg)
pi_coeff = _pi_coeff(arg)
if pi_coeff is not None:
if pi_coeff.is_integer:
if fuzzy_not(arg.is_zero):
return S.Zero
elif (2*pi_coeff).is_integer:
return S.NegativeOne**(pi_coeff - S.Half)/arg
def _eval_nseries(self, x, n, logx, cdir=0):
x = self.args[0]
return (sin(x)/x)._eval_nseries(x, n, logx)
def _eval_rewrite_as_jn(self, arg, **kwargs):
from sympy.functions.special.bessel import jn
return jn(0, arg)
def _eval_rewrite_as_sin(self, arg, **kwargs):
return Piecewise((sin(arg)/arg, Ne(arg, S.Zero)), (S.One, S.true))
###############################################################################
########################### TRIGONOMETRIC INVERSES ############################
###############################################################################
class InverseTrigonometricFunction(Function):
"""Base class for inverse trigonometric functions."""
_singularities = (S.One, S.NegativeOne, S.Zero, S.ComplexInfinity) # type: Tuple[Expr, ...]
@staticmethod
def _asin_table():
# Only keys with could_extract_minus_sign() == False
# are actually needed.
return {
sqrt(3)/2: S.Pi/3,
sqrt(2)/2: S.Pi/4,
1/sqrt(2): S.Pi/4,
sqrt((5 - sqrt(5))/8): S.Pi/5,
sqrt(2)*sqrt(5 - sqrt(5))/4: S.Pi/5,
sqrt((5 + sqrt(5))/8): S.Pi*Rational(2, 5),
sqrt(2)*sqrt(5 + sqrt(5))/4: S.Pi*Rational(2, 5),
S.Half: S.Pi/6,
sqrt(2 - sqrt(2))/2: S.Pi/8,
sqrt(S.Half - sqrt(2)/4): S.Pi/8,
sqrt(2 + sqrt(2))/2: S.Pi*Rational(3, 8),
sqrt(S.Half + sqrt(2)/4): S.Pi*Rational(3, 8),
(sqrt(5) - 1)/4: S.Pi/10,
(1 - sqrt(5))/4: -S.Pi/10,
(sqrt(5) + 1)/4: S.Pi*Rational(3, 10),
sqrt(6)/4 - sqrt(2)/4: S.Pi/12,
-sqrt(6)/4 + sqrt(2)/4: -S.Pi/12,
(sqrt(3) - 1)/sqrt(8): S.Pi/12,
(1 - sqrt(3))/sqrt(8): -S.Pi/12,
sqrt(6)/4 + sqrt(2)/4: S.Pi*Rational(5, 12),
(1 + sqrt(3))/sqrt(8): S.Pi*Rational(5, 12)
}
@staticmethod
def _atan_table():
# Only keys with could_extract_minus_sign() == False
# are actually needed.
return {
sqrt(3)/3: S.Pi/6,
1/sqrt(3): S.Pi/6,
sqrt(3): S.Pi/3,
sqrt(2) - 1: S.Pi/8,
1 - sqrt(2): -S.Pi/8,
1 + sqrt(2): S.Pi*Rational(3, 8),
sqrt(5 - 2*sqrt(5)): S.Pi/5,
sqrt(5 + 2*sqrt(5)): S.Pi*Rational(2, 5),
sqrt(1 - 2*sqrt(5)/5): S.Pi/10,
sqrt(1 + 2*sqrt(5)/5): S.Pi*Rational(3, 10),
2 - sqrt(3): S.Pi/12,
-2 + sqrt(3): -S.Pi/12,
2 + sqrt(3): S.Pi*Rational(5, 12)
}
@staticmethod
def _acsc_table():
# Keys for which could_extract_minus_sign()
# will obviously return True are omitted.
return {
2*sqrt(3)/3: S.Pi/3,
sqrt(2): S.Pi/4,
sqrt(2 + 2*sqrt(5)/5): S.Pi/5,
1/sqrt(Rational(5, 8) - sqrt(5)/8): S.Pi/5,
sqrt(2 - 2*sqrt(5)/5): S.Pi*Rational(2, 5),
1/sqrt(Rational(5, 8) + sqrt(5)/8): S.Pi*Rational(2, 5),
2: S.Pi/6,
sqrt(4 + 2*sqrt(2)): S.Pi/8,
2/sqrt(2 - sqrt(2)): S.Pi/8,
sqrt(4 - 2*sqrt(2)): S.Pi*Rational(3, 8),
2/sqrt(2 + sqrt(2)): S.Pi*Rational(3, 8),
1 + sqrt(5): S.Pi/10,
sqrt(5) - 1: S.Pi*Rational(3, 10),
-(sqrt(5) - 1): S.Pi*Rational(-3, 10),
sqrt(6) + sqrt(2): S.Pi/12,
sqrt(6) - sqrt(2): S.Pi*Rational(5, 12),
-(sqrt(6) - sqrt(2)): S.Pi*Rational(-5, 12)
}
class asin(InverseTrigonometricFunction):
"""
The inverse sine function.
Returns the arcsine of x in radians.
Explanation
===========
``asin(x)`` will evaluate automatically in the cases ``oo``, ``-oo``,
``0``, ``1``, ``-1`` and for some instances when the result is a rational
multiple of pi (see the eval class method).
A purely imaginary argument will lead to an asinh expression.
Examples
========
>>> from sympy import asin, oo
>>> asin(1)
pi/2
>>> asin(-1)
-pi/2
>>> asin(-oo)
oo*I
>>> asin(oo)
-oo*I
See Also
========
sin, csc, cos, sec, tan, cot
acsc, acos, asec, atan, acot, atan2
References
==========
.. [1] https://en.wikipedia.org/wiki/Inverse_trigonometric_functions
.. [2] http://dlmf.nist.gov/4.23
.. [3] http://functions.wolfram.com/ElementaryFunctions/ArcSin
"""
def fdiff(self, argindex=1):
if argindex == 1:
return 1/sqrt(1 - self.args[0]**2)
else:
raise ArgumentIndexError(self, argindex)
def _eval_is_rational(self):
s = self.func(*self.args)
if s.func == self.func:
if s.args[0].is_rational:
return False
else:
return s.is_rational
def _eval_is_positive(self):
return self._eval_is_extended_real() and self.args[0].is_positive
def _eval_is_negative(self):
return self._eval_is_extended_real() and self.args[0].is_negative
@classmethod
def eval(cls, arg):
if arg.is_Number:
if arg is S.NaN:
return S.NaN
elif arg is S.Infinity:
return S.NegativeInfinity*S.ImaginaryUnit
elif arg is S.NegativeInfinity:
return S.Infinity*S.ImaginaryUnit
elif arg.is_zero:
return S.Zero
elif arg is S.One:
return S.Pi/2
elif arg is S.NegativeOne:
return -S.Pi/2
if arg is S.ComplexInfinity:
return S.ComplexInfinity
if arg.could_extract_minus_sign():
return -cls(-arg)
if arg.is_number:
asin_table = cls._asin_table()
if arg in asin_table:
return asin_table[arg]
i_coeff = arg.as_coefficient(S.ImaginaryUnit)
if i_coeff is not None:
return S.ImaginaryUnit*asinh(i_coeff)
if arg.is_zero:
return S.Zero
if isinstance(arg, sin):
ang = arg.args[0]
if ang.is_comparable:
ang %= 2*pi # restrict to [0,2*pi)
if ang > pi: # restrict to (-pi,pi]
ang = pi - ang
# restrict to [-pi/2,pi/2]
if ang > pi/2:
ang = pi - ang
if ang < -pi/2:
ang = -pi - ang
return ang
if isinstance(arg, cos): # acos(x) + asin(x) = pi/2
ang = arg.args[0]
if ang.is_comparable:
return pi/2 - acos(arg)
@staticmethod
@cacheit
def taylor_term(n, x, *previous_terms):
if n < 0 or n % 2 == 0:
return S.Zero
else:
x = sympify(x)
if len(previous_terms) >= 2 and n > 2:
p = previous_terms[-2]
return p*(n - 2)**2/(n*(n - 1))*x**2
else:
k = (n - 1) // 2
R = RisingFactorial(S.Half, k)
F = factorial(k)
return R/F*x**n/n
def _eval_as_leading_term(self, x, logx=None, cdir=0):
from sympy import I, im, log
arg = self.args[0]
x0 = arg.subs(x, 0).cancel()
if x0.is_zero:
return arg.as_leading_term(x)
if x0 is S.ComplexInfinity:
return I*log(arg.as_leading_term(x))
if cdir != 0:
cdir = arg.dir(x, cdir)
if im(cdir) < 0 and x0.is_real and x0 < S.NegativeOne:
return -S.Pi - self.func(x0)
elif im(cdir) > 0 and x0.is_real and x0 > S.One:
return S.Pi - self.func(x0)
return self.func(x0)
def _eval_nseries(self, x, n, logx, cdir=0): #asin
from sympy import Dummy, im, O
arg0 = self.args[0].subs(x, 0)
if arg0 is S.One:
t = Dummy('t', positive=True)
ser = asin(S.One - t**2).rewrite(log).nseries(t, 0, 2*n)
arg1 = S.One - self.args[0]
f = arg1.as_leading_term(x)
g = (arg1 - f)/ f
if not g.is_meromorphic(x, 0): # cannot be expanded
return O(1) if n == 0 else S.Pi/2 + O(sqrt(x))
res1 = sqrt(S.One + g)._eval_nseries(x, n=n, logx=logx)
res = (res1.removeO()*sqrt(f)).expand()
return ser.removeO().subs(t, res).expand().powsimp() + O(x**n, x)
if arg0 is S.NegativeOne:
t = Dummy('t', positive=True)
ser = asin(S.NegativeOne + t**2).rewrite(log).nseries(t, 0, 2*n)
arg1 = S.One + self.args[0]
f = arg1.as_leading_term(x)
g = (arg1 - f)/ f
if not g.is_meromorphic(x, 0): # cannot be expanded
return O(1) if n == 0 else -S.Pi/2 + O(sqrt(x))
res1 = sqrt(S.One + g)._eval_nseries(x, n=n, logx=logx)
res = (res1.removeO()*sqrt(f)).expand()
return ser.removeO().subs(t, res).expand().powsimp() + O(x**n, x)
res = Function._eval_nseries(self, x, n=n, logx=logx)
if arg0 is S.ComplexInfinity:
return res
if cdir != 0:
cdir = self.args[0].dir(x, cdir)
if im(cdir) < 0 and arg0.is_real and arg0 < S.NegativeOne:
return -S.Pi - res
elif im(cdir) > 0 and arg0.is_real and arg0 > S.One:
return S.Pi - res
return res
def _eval_rewrite_as_acos(self, x, **kwargs):
return S.Pi/2 - acos(x)
def _eval_rewrite_as_atan(self, x, **kwargs):
return 2*atan(x/(1 + sqrt(1 - x**2)))
def _eval_rewrite_as_log(self, x, **kwargs):
return -S.ImaginaryUnit*log(S.ImaginaryUnit*x + sqrt(1 - x**2))
def _eval_rewrite_as_acot(self, arg, **kwargs):
return 2*acot((1 + sqrt(1 - arg**2))/arg)
def _eval_rewrite_as_asec(self, arg, **kwargs):
return S.Pi/2 - asec(1/arg)
def _eval_rewrite_as_acsc(self, arg, **kwargs):
return acsc(1/arg)
def _eval_is_extended_real(self):
x = self.args[0]
return x.is_extended_real and (1 - abs(x)).is_nonnegative
def inverse(self, argindex=1):
"""
Returns the inverse of this function.
"""
return sin
class acos(InverseTrigonometricFunction):
"""
The inverse cosine function.
Returns the arc cosine of x (measured in radians).
Examples
========
``acos(x)`` will evaluate automatically in the cases
``oo``, ``-oo``, ``0``, ``1``, ``-1`` and for some instances when
the result is a rational multiple of pi (see the eval class method).
``acos(zoo)`` evaluates to ``zoo``
(see note in :class:`sympy.functions.elementary.trigonometric.asec`)
A purely imaginary argument will be rewritten to asinh.
Examples
========
>>> from sympy import acos, oo
>>> acos(1)
0
>>> acos(0)
pi/2
>>> acos(oo)
oo*I
See Also
========
sin, csc, cos, sec, tan, cot
asin, acsc, asec, atan, acot, atan2
References
==========
.. [1] https://en.wikipedia.org/wiki/Inverse_trigonometric_functions
.. [2] http://dlmf.nist.gov/4.23
.. [3] http://functions.wolfram.com/ElementaryFunctions/ArcCos
"""
def fdiff(self, argindex=1):
if argindex == 1:
return -1/sqrt(1 - self.args[0]**2)
else:
raise ArgumentIndexError(self, argindex)
def _eval_is_rational(self):
s = self.func(*self.args)
if s.func == self.func:
if s.args[0].is_rational:
return False
else:
return s.is_rational
@classmethod
def eval(cls, arg):
if arg.is_Number:
if arg is S.NaN:
return S.NaN
elif arg is S.Infinity:
return S.Infinity*S.ImaginaryUnit
elif arg is S.NegativeInfinity:
return S.NegativeInfinity*S.ImaginaryUnit
elif arg.is_zero:
return S.Pi/2
elif arg is S.One:
return S.Zero
elif arg is S.NegativeOne:
return S.Pi
if arg is S.ComplexInfinity:
return S.ComplexInfinity
if arg.is_number:
asin_table = cls._asin_table()
if arg in asin_table:
return pi/2 - asin_table[arg]
elif -arg in asin_table:
return pi/2 + asin_table[-arg]
i_coeff = arg.as_coefficient(S.ImaginaryUnit)
if i_coeff is not None:
return pi/2 - asin(arg)
if isinstance(arg, cos):
ang = arg.args[0]
if ang.is_comparable:
ang %= 2*pi # restrict to [0,2*pi)
if ang > pi: # restrict to [0,pi]
ang = 2*pi - ang
return ang
if isinstance(arg, sin): # acos(x) + asin(x) = pi/2
ang = arg.args[0]
if ang.is_comparable:
return pi/2 - asin(arg)
@staticmethod
@cacheit
def taylor_term(n, x, *previous_terms):
if n == 0:
return S.Pi/2
elif n < 0 or n % 2 == 0:
return S.Zero
else:
x = sympify(x)
if len(previous_terms) >= 2 and n > 2:
p = previous_terms[-2]
return p*(n - 2)**2/(n*(n - 1))*x**2
else:
k = (n - 1) // 2
R = RisingFactorial(S.Half, k)
F = factorial(k)
return -R/F*x**n/n
def _eval_as_leading_term(self, x, logx=None, cdir=0):
from sympy import I, im, log
arg = self.args[0]
x0 = arg.subs(x, 0).cancel()
if x0 == 1:
return sqrt(2)*sqrt((S.One - arg).as_leading_term(x))
if x0 is S.ComplexInfinity:
return I*log(arg.as_leading_term(x))
if cdir != 0:
cdir = arg.dir(x, cdir)
if im(cdir) < 0 and x0.is_real and x0 < S.NegativeOne:
return 2*S.Pi - self.func(x0)
elif im(cdir) > 0 and x0.is_real and x0 > S.One:
return -self.func(x0)
return self.func(x0)
def _eval_is_extended_real(self):
x = self.args[0]
return x.is_extended_real and (1 - abs(x)).is_nonnegative
def _eval_is_nonnegative(self):
return self._eval_is_extended_real()
def _eval_nseries(self, x, n, logx, cdir=0): #acos
from sympy import Dummy, im, O
arg0 = self.args[0].subs(x, 0)
if arg0 is S.One:
t = Dummy('t', positive=True)
ser = acos(S.One - t**2).rewrite(log).nseries(t, 0, 2*n)
arg1 = S.One - self.args[0]
f = arg1.as_leading_term(x)
g = (arg1 - f)/ f
if not g.is_meromorphic(x, 0): # cannot be expanded
return O(1) if n == 0 else O(sqrt(x))
res1 = sqrt(S.One + g)._eval_nseries(x, n=n, logx=logx)
res = (res1.removeO()*sqrt(f)).expand()
return ser.removeO().subs(t, res).expand().powsimp() + O(x**n, x)
if arg0 is S.NegativeOne:
t = Dummy('t', positive=True)
ser = acos(S.NegativeOne + t**2).rewrite(log).nseries(t, 0, 2*n)
arg1 = S.One + self.args[0]
f = arg1.as_leading_term(x)
g = (arg1 - f)/ f
if not g.is_meromorphic(x, 0): # cannot be expanded
return O(1) if n == 0 else S.Pi + O(sqrt(x))
res1 = sqrt(S.One + g)._eval_nseries(x, n=n, logx=logx)
res = (res1.removeO()*sqrt(f)).expand()
return ser.removeO().subs(t, res).expand().powsimp() + O(x**n, x)
res = Function._eval_nseries(self, x, n=n, logx=logx)
if arg0 is S.ComplexInfinity:
return res
if cdir != 0:
cdir = self.args[0].dir(x, cdir)
if im(cdir) < 0 and arg0.is_real and arg0 < S.NegativeOne:
return 2*S.Pi - res
elif im(cdir) > 0 and arg0.is_real and arg0 > S.One:
return -res
return res
def _eval_rewrite_as_log(self, x, **kwargs):
return S.Pi/2 + S.ImaginaryUnit*\
log(S.ImaginaryUnit*x + sqrt(1 - x**2))
def _eval_rewrite_as_asin(self, x, **kwargs):
return S.Pi/2 - asin(x)
def _eval_rewrite_as_atan(self, x, **kwargs):
return atan(sqrt(1 - x**2)/x) + (S.Pi/2)*(1 - x*sqrt(1/x**2))
def inverse(self, argindex=1):
"""
Returns the inverse of this function.
"""
return cos
def _eval_rewrite_as_acot(self, arg, **kwargs):
return S.Pi/2 - 2*acot((1 + sqrt(1 - arg**2))/arg)
def _eval_rewrite_as_asec(self, arg, **kwargs):
return asec(1/arg)
def _eval_rewrite_as_acsc(self, arg, **kwargs):
return S.Pi/2 - acsc(1/arg)
def _eval_conjugate(self):
z = self.args[0]
r = self.func(self.args[0].conjugate())
if z.is_extended_real is False:
return r
elif z.is_extended_real and (z + 1).is_nonnegative and (z - 1).is_nonpositive:
return r
class atan(InverseTrigonometricFunction):
"""
The inverse tangent function.
Returns the arc tangent of x (measured in radians).
Explanation
===========
``atan(x)`` will evaluate automatically in the cases
``oo``, ``-oo``, ``0``, ``1``, ``-1`` and for some instances when the
result is a rational multiple of pi (see the eval class method).
Examples
========
>>> from sympy import atan, oo
>>> atan(0)
0
>>> atan(1)
pi/4
>>> atan(oo)
pi/2
See Also
========
sin, csc, cos, sec, tan, cot
asin, acsc, acos, asec, acot, atan2
References
==========
.. [1] https://en.wikipedia.org/wiki/Inverse_trigonometric_functions
.. [2] http://dlmf.nist.gov/4.23
.. [3] http://functions.wolfram.com/ElementaryFunctions/ArcTan
"""
_singularities = (S.ImaginaryUnit, -S.ImaginaryUnit)
def fdiff(self, argindex=1):
if argindex == 1:
return 1/(1 + self.args[0]**2)
else:
raise ArgumentIndexError(self, argindex)
def _eval_is_rational(self):
s = self.func(*self.args)
if s.func == self.func:
if s.args[0].is_rational:
return False
else:
return s.is_rational
def _eval_is_positive(self):
return self.args[0].is_extended_positive
def _eval_is_nonnegative(self):
return self.args[0].is_extended_nonnegative
def _eval_is_zero(self):
return self.args[0].is_zero
def _eval_is_real(self):
return self.args[0].is_extended_real
@classmethod
def eval(cls, arg):
if arg.is_Number:
if arg is S.NaN:
return S.NaN
elif arg is S.Infinity:
return S.Pi/2
elif arg is S.NegativeInfinity:
return -S.Pi/2
elif arg.is_zero:
return S.Zero
elif arg is S.One:
return S.Pi/4
elif arg is S.NegativeOne:
return -S.Pi/4
if arg is S.ComplexInfinity:
from sympy.calculus.util import AccumBounds
return AccumBounds(-S.Pi/2, S.Pi/2)
if arg.could_extract_minus_sign():
return -cls(-arg)
if arg.is_number:
atan_table = cls._atan_table()
if arg in atan_table:
return atan_table[arg]
i_coeff = arg.as_coefficient(S.ImaginaryUnit)
if i_coeff is not None:
return S.ImaginaryUnit*atanh(i_coeff)
if arg.is_zero:
return S.Zero
if isinstance(arg, tan):
ang = arg.args[0]
if ang.is_comparable:
ang %= pi # restrict to [0,pi)
if ang > pi/2: # restrict to [-pi/2,pi/2]
ang -= pi
return ang
if isinstance(arg, cot): # atan(x) + acot(x) = pi/2
ang = arg.args[0]
if ang.is_comparable:
ang = pi/2 - acot(arg)
if ang > pi/2: # restrict to [-pi/2,pi/2]
ang -= pi
return ang
@staticmethod
@cacheit
def taylor_term(n, x, *previous_terms):
if n < 0 or n % 2 == 0:
return S.Zero
else:
x = sympify(x)
return (-1)**((n - 1)//2)*x**n/n
def _eval_as_leading_term(self, x, logx=None, cdir=0):
from sympy import im, re
arg = self.args[0]
x0 = arg.subs(x, 0).cancel()
if x0.is_zero:
return arg.as_leading_term(x)
if x0 is S.ComplexInfinity:
return acot(1/arg)._eval_as_leading_term(x, cdir=cdir)
if cdir != 0:
cdir = arg.dir(x, cdir)
if re(cdir) < 0 and re(x0).is_zero and im(x0) > S.One:
return self.func(x0) - S.Pi
elif re(cdir) > 0 and re(x0).is_zero and im(x0) < S.NegativeOne:
return self.func(x0) + S.Pi
return self.func(x0)
def _eval_nseries(self, x, n, logx, cdir=0): #atan
from sympy import im, re
arg0 = self.args[0].subs(x, 0)
res = Function._eval_nseries(self, x, n=n, logx=logx)
if cdir != 0:
cdir = self.args[0].dir(x, cdir)
if arg0 is S.ComplexInfinity:
if re(cdir) > 0:
return res - S.Pi
return res
if re(cdir) < 0 and re(arg0).is_zero and im(arg0) > S.One:
return res - S.Pi
elif re(cdir) > 0 and re(arg0).is_zero and im(arg0) < S.NegativeOne:
return res + S.Pi
return res
def _eval_rewrite_as_log(self, x, **kwargs):
return S.ImaginaryUnit/2*(log(S.One - S.ImaginaryUnit*x)
- log(S.One + S.ImaginaryUnit*x))
def _eval_aseries(self, n, args0, x, logx):
if args0[0] is S.Infinity:
return (S.Pi/2 - atan(1/self.args[0]))._eval_nseries(x, n, logx)
elif args0[0] is S.NegativeInfinity:
return (-S.Pi/2 - atan(1/self.args[0]))._eval_nseries(x, n, logx)
else:
return super()._eval_aseries(n, args0, x, logx)
def inverse(self, argindex=1):
"""
Returns the inverse of this function.
"""
return tan
def _eval_rewrite_as_asin(self, arg, **kwargs):
return sqrt(arg**2)/arg*(S.Pi/2 - asin(1/sqrt(1 + arg**2)))
def _eval_rewrite_as_acos(self, arg, **kwargs):
return sqrt(arg**2)/arg*acos(1/sqrt(1 + arg**2))
def _eval_rewrite_as_acot(self, arg, **kwargs):
return acot(1/arg)
def _eval_rewrite_as_asec(self, arg, **kwargs):
return sqrt(arg**2)/arg*asec(sqrt(1 + arg**2))
def _eval_rewrite_as_acsc(self, arg, **kwargs):
return sqrt(arg**2)/arg*(S.Pi/2 - acsc(sqrt(1 + arg**2)))
class acot(InverseTrigonometricFunction):
r"""
The inverse cotangent function.
Returns the arc cotangent of x (measured in radians).
Explanation
===========
``acot(x)`` will evaluate automatically in the cases ``oo``, ``-oo``,
``zoo``, ``0``, ``1``, ``-1`` and for some instances when the result is a
rational multiple of pi (see the eval class method).
A purely imaginary argument will lead to an ``acoth`` expression.
``acot(x)`` has a branch cut along `(-i, i)`, hence it is discontinuous
at 0. Its range for real ``x`` is `(-\frac{\pi}{2}, \frac{\pi}{2}]`.
Examples
========
>>> from sympy import acot, sqrt
>>> acot(0)
pi/2
>>> acot(1)
pi/4
>>> acot(sqrt(3) - 2)
-5*pi/12
See Also
========
sin, csc, cos, sec, tan, cot
asin, acsc, acos, asec, atan, atan2
References
==========
.. [1] http://dlmf.nist.gov/4.23
.. [2] http://functions.wolfram.com/ElementaryFunctions/ArcCot
"""
_singularities = (S.ImaginaryUnit, -S.ImaginaryUnit)
def fdiff(self, argindex=1):
if argindex == 1:
return -1/(1 + self.args[0]**2)
else:
raise ArgumentIndexError(self, argindex)
def _eval_is_rational(self):
s = self.func(*self.args)
if s.func == self.func:
if s.args[0].is_rational:
return False
else:
return s.is_rational
def _eval_is_positive(self):
return self.args[0].is_nonnegative
def _eval_is_negative(self):
return self.args[0].is_negative
def _eval_is_extended_real(self):
return self.args[0].is_extended_real
@classmethod
def eval(cls, arg):
if arg.is_Number:
if arg is S.NaN:
return S.NaN
elif arg is S.Infinity:
return S.Zero
elif arg is S.NegativeInfinity:
return S.Zero
elif arg.is_zero:
return S.Pi/ 2
elif arg is S.One:
return S.Pi/4
elif arg is S.NegativeOne:
return -S.Pi/4
if arg is S.ComplexInfinity:
return S.Zero
if arg.could_extract_minus_sign():
return -cls(-arg)
if arg.is_number:
atan_table = cls._atan_table()
if arg in atan_table:
ang = pi/2 - atan_table[arg]
if ang > pi/2: # restrict to (-pi/2,pi/2]
ang -= pi
return ang
i_coeff = arg.as_coefficient(S.ImaginaryUnit)
if i_coeff is not None:
return -S.ImaginaryUnit*acoth(i_coeff)
if arg.is_zero:
return S.Pi*S.Half
if isinstance(arg, cot):
ang = arg.args[0]
if ang.is_comparable:
ang %= pi # restrict to [0,pi)
if ang > pi/2: # restrict to (-pi/2,pi/2]
ang -= pi;
return ang
if isinstance(arg, tan): # atan(x) + acot(x) = pi/2
ang = arg.args[0]
if ang.is_comparable:
ang = pi/2 - atan(arg)
if ang > pi/2: # restrict to (-pi/2,pi/2]
ang -= pi
return ang
@staticmethod
@cacheit
def taylor_term(n, x, *previous_terms):
if n == 0:
return S.Pi/2 # FIX THIS
elif n < 0 or n % 2 == 0:
return S.Zero
else:
x = sympify(x)
return (-1)**((n + 1)//2)*x**n/n
def _eval_as_leading_term(self, x, logx=None, cdir=0):
from sympy import im, re
arg = self.args[0]
x0 = arg.subs(x, 0).cancel()
if x0 is S.ComplexInfinity:
return (1/arg).as_leading_term(x)
if cdir != 0:
cdir = arg.dir(x, cdir)
if x0.is_zero:
if re(cdir) < 0:
return self.func(x0) - S.Pi
return self.func(x0)
if re(cdir) > 0 and re(x0).is_zero and im(x0) > S.Zero and im(x0) < S.One:
return self.func(x0) + S.Pi
if re(cdir) < 0 and re(x0).is_zero and im(x0) < S.Zero and im(x0) > S.NegativeOne:
return self.func(x0) - S.Pi
return self.func(x0)
def _eval_nseries(self, x, n, logx, cdir=0): #acot
from sympy import im, re
arg0 = self.args[0].subs(x, 0)
res = Function._eval_nseries(self, x, n=n, logx=logx)
if arg0 is S.ComplexInfinity:
return res
if cdir != 0:
cdir = self.args[0].dir(x, cdir)
if arg0.is_zero:
if re(cdir) < 0:
return res - S.Pi
return res
if re(cdir) > 0 and re(arg0).is_zero and im(arg0) > S.Zero and im(arg0) < S.One:
return res + S.Pi
if re(cdir) < 0 and re(arg0).is_zero and im(arg0) < S.Zero and im(arg0) > S.NegativeOne:
return res - S.Pi
return res
def _eval_aseries(self, n, args0, x, logx):
if args0[0] is S.Infinity:
return (S.Pi/2 - acot(1/self.args[0]))._eval_nseries(x, n, logx)
elif args0[0] is S.NegativeInfinity:
return (S.Pi*Rational(3, 2) - acot(1/self.args[0]))._eval_nseries(x, n, logx)
else:
return super(atan, self)._eval_aseries(n, args0, x, logx)
def _eval_rewrite_as_log(self, x, **kwargs):
return S.ImaginaryUnit/2*(log(1 - S.ImaginaryUnit/x)
- log(1 + S.ImaginaryUnit/x))
def inverse(self, argindex=1):
"""
Returns the inverse of this function.
"""
return cot
def _eval_rewrite_as_asin(self, arg, **kwargs):
return (arg*sqrt(1/arg**2)*
(S.Pi/2 - asin(sqrt(-arg**2)/sqrt(-arg**2 - 1))))
def _eval_rewrite_as_acos(self, arg, **kwargs):
return arg*sqrt(1/arg**2)*acos(sqrt(-arg**2)/sqrt(-arg**2 - 1))
def _eval_rewrite_as_atan(self, arg, **kwargs):
return atan(1/arg)
def _eval_rewrite_as_asec(self, arg, **kwargs):
return arg*sqrt(1/arg**2)*asec(sqrt((1 + arg**2)/arg**2))
def _eval_rewrite_as_acsc(self, arg, **kwargs):
return arg*sqrt(1/arg**2)*(S.Pi/2 - acsc(sqrt((1 + arg**2)/arg**2)))
class asec(InverseTrigonometricFunction):
r"""
The inverse secant function.
Returns the arc secant of x (measured in radians).
Explanation
===========
``asec(x)`` will evaluate automatically in the cases ``oo``, ``-oo``,
``0``, ``1``, ``-1`` and for some instances when the result is a rational
multiple of pi (see the eval class method).
``asec(x)`` has branch cut in the interval [-1, 1]. For complex arguments,
it can be defined [4]_ as
.. math::
\operatorname{sec^{-1}}(z) = -i\frac{\log\left(\sqrt{1 - z^2} + 1\right)}{z}
At ``x = 0``, for positive branch cut, the limit evaluates to ``zoo``. For
negative branch cut, the limit
.. math::
\lim_{z \to 0}-i\frac{\log\left(-\sqrt{1 - z^2} + 1\right)}{z}
simplifies to :math:`-i\log\left(z/2 + O\left(z^3\right)\right)` which
ultimately evaluates to ``zoo``.
As ``acos(x)`` = ``asec(1/x)``, a similar argument can be given for
``acos(x)``.
Examples
========
>>> from sympy import asec, oo
>>> asec(1)
0
>>> asec(-1)
pi
>>> asec(0)
zoo
>>> asec(-oo)
pi/2
See Also
========
sin, csc, cos, sec, tan, cot
asin, acsc, acos, atan, acot, atan2
References
==========
.. [1] https://en.wikipedia.org/wiki/Inverse_trigonometric_functions
.. [2] http://dlmf.nist.gov/4.23
.. [3] http://functions.wolfram.com/ElementaryFunctions/ArcSec
.. [4] http://reference.wolfram.com/language/ref/ArcSec.html
"""
@classmethod
def eval(cls, arg):
if arg.is_zero:
return S.ComplexInfinity
if arg.is_Number:
if arg is S.NaN:
return S.NaN
elif arg is S.One:
return S.Zero
elif arg is S.NegativeOne:
return S.Pi
if arg in [S.Infinity, S.NegativeInfinity, S.ComplexInfinity]:
return S.Pi/2
if arg.is_number:
acsc_table = cls._acsc_table()
if arg in acsc_table:
return pi/2 - acsc_table[arg]
elif -arg in acsc_table:
return pi/2 + acsc_table[-arg]
if isinstance(arg, sec):
ang = arg.args[0]
if ang.is_comparable:
ang %= 2*pi # restrict to [0,2*pi)
if ang > pi: # restrict to [0,pi]
ang = 2*pi - ang
return ang
if isinstance(arg, csc): # asec(x) + acsc(x) = pi/2
ang = arg.args[0]
if ang.is_comparable:
return pi/2 - acsc(arg)
def fdiff(self, argindex=1):
if argindex == 1:
return 1/(self.args[0]**2*sqrt(1 - 1/self.args[0]**2))
else:
raise ArgumentIndexError(self, argindex)
def inverse(self, argindex=1):
"""
Returns the inverse of this function.
"""
return sec
def _eval_as_leading_term(self, x, logx=None, cdir=0):
from sympy import I, im, log
arg = self.args[0]
x0 = arg.subs(x, 0).cancel()
if x0 == 1:
return sqrt(2)*sqrt((arg - S.One).as_leading_term(x))
if x0.is_zero:
return I*log(arg.as_leading_term(x))
if cdir != 0:
cdir = arg.dir(x, cdir)
if im(cdir) < 0 and x0.is_real and x0 > S.Zero and x0 < S.One:
return -self.func(x0)
elif im(cdir) > 0 and x0.is_real and x0 < S.Zero and x0 > S.NegativeOne:
return 2*S.Pi - self.func(x0)
return self.func(x0)
def _eval_nseries(self, x, n, logx, cdir=0): #asec
from sympy import Dummy, im, O
arg0 = self.args[0].subs(x, 0)
if arg0 is S.One:
t = Dummy('t', positive=True)
ser = asec(S.One + t**2).rewrite(log).nseries(t, 0, 2*n)
arg1 = S.NegativeOne + self.args[0]
f = arg1.as_leading_term(x)
g = (arg1 - f)/ f
res1 = sqrt(S.One + g)._eval_nseries(x, n=n, logx=logx)
res = (res1.removeO()*sqrt(f)).expand()
return ser.removeO().subs(t, res).expand().powsimp() + O(x**n, x)
if arg0 is S.NegativeOne:
t = Dummy('t', positive=True)
ser = asec(S.NegativeOne - t**2).rewrite(log).nseries(t, 0, 2*n)
arg1 = S.NegativeOne - self.args[0]
f = arg1.as_leading_term(x)
g = (arg1 - f)/ f
res1 = sqrt(S.One + g)._eval_nseries(x, n=n, logx=logx)
res = (res1.removeO()*sqrt(f)).expand()
return ser.removeO().subs(t, res).expand().powsimp() + O(x**n, x)
res = Function._eval_nseries(self, x, n=n, logx=logx)
if arg0 is S.ComplexInfinity:
return res
if cdir != 0:
cdir = self.args[0].dir(x, cdir)
if im(cdir) < 0 and arg0.is_real and arg0 > S.Zero and arg0 < S.One:
return -res
elif im(cdir) > 0 and arg0.is_real and arg0 < S.Zero and arg0 > S.NegativeOne:
return 2*S.Pi - res
return res
def _eval_is_extended_real(self):
x = self.args[0]
if x.is_extended_real is False:
return False
return fuzzy_or(((x - 1).is_nonnegative, (-x - 1).is_nonnegative))
def _eval_rewrite_as_log(self, arg, **kwargs):
return S.Pi/2 + S.ImaginaryUnit*log(S.ImaginaryUnit/arg + sqrt(1 - 1/arg**2))
def _eval_rewrite_as_asin(self, arg, **kwargs):
return S.Pi/2 - asin(1/arg)
def _eval_rewrite_as_acos(self, arg, **kwargs):
return acos(1/arg)
def _eval_rewrite_as_atan(self, arg, **kwargs):
return sqrt(arg**2)/arg*(-S.Pi/2 + 2*atan(arg + sqrt(arg**2 - 1)))
def _eval_rewrite_as_acot(self, arg, **kwargs):
return sqrt(arg**2)/arg*(-S.Pi/2 + 2*acot(arg - sqrt(arg**2 - 1)))
def _eval_rewrite_as_acsc(self, arg, **kwargs):
return S.Pi/2 - acsc(arg)
class acsc(InverseTrigonometricFunction):
"""
The inverse cosecant function.
Returns the arc cosecant of x (measured in radians).
Explanation
===========
``acsc(x)`` will evaluate automatically in the cases ``oo``, ``-oo``,
``0``, ``1``, ``-1`` and for some instances when the result is a rational
multiple of pi (see the eval class method).
Examples
========
>>> from sympy import acsc, oo
>>> acsc(1)
pi/2
>>> acsc(-1)
-pi/2
>>> acsc(oo)
0
>>> acsc(-oo) == acsc(oo)
True
>>> acsc(0)
zoo
See Also
========
sin, csc, cos, sec, tan, cot
asin, acos, asec, atan, acot, atan2
References
==========
.. [1] https://en.wikipedia.org/wiki/Inverse_trigonometric_functions
.. [2] http://dlmf.nist.gov/4.23
.. [3] http://functions.wolfram.com/ElementaryFunctions/ArcCsc
"""
@classmethod
def eval(cls, arg):
if arg.is_zero:
return S.ComplexInfinity
if arg.is_Number:
if arg is S.NaN:
return S.NaN
elif arg is S.One:
return S.Pi/2
elif arg is S.NegativeOne:
return -S.Pi/2
if arg in [S.Infinity, S.NegativeInfinity, S.ComplexInfinity]:
return S.Zero
if arg.could_extract_minus_sign():
return -cls(-arg)
if arg.is_number:
acsc_table = cls._acsc_table()
if arg in acsc_table:
return acsc_table[arg]
if isinstance(arg, csc):
ang = arg.args[0]
if ang.is_comparable:
ang %= 2*pi # restrict to [0,2*pi)
if ang > pi: # restrict to (-pi,pi]
ang = pi - ang
# restrict to [-pi/2,pi/2]
if ang > pi/2:
ang = pi - ang
if ang < -pi/2:
ang = -pi - ang
return ang
if isinstance(arg, sec): # asec(x) + acsc(x) = pi/2
ang = arg.args[0]
if ang.is_comparable:
return pi/2 - asec(arg)
def fdiff(self, argindex=1):
if argindex == 1:
return -1/(self.args[0]**2*sqrt(1 - 1/self.args[0]**2))
else:
raise ArgumentIndexError(self, argindex)
def inverse(self, argindex=1):
"""
Returns the inverse of this function.
"""
return csc
def _eval_as_leading_term(self, x, logx=None, cdir=0):
from sympy import I, im, log
arg = self.args[0]
x0 = arg.subs(x, 0).cancel()
if x0.is_zero:
return I*log(arg.as_leading_term(x))
if x0 is S.ComplexInfinity:
return arg.as_leading_term(x)
if cdir != 0:
cdir = arg.dir(x, cdir)
if im(cdir) < 0 and x0.is_real and x0 > S.Zero and x0 < S.One:
return S.Pi - self.func(x0)
elif im(cdir) > 0 and x0.is_real and x0 < S.Zero and x0 > S.NegativeOne:
return -S.Pi - self.func(x0)
return self.func(x0)
def _eval_nseries(self, x, n, logx, cdir=0): #acsc
from sympy import Dummy, im, O
arg0 = self.args[0].subs(x, 0)
if arg0 is S.One:
t = Dummy('t', positive=True)
ser = acsc(S.One + t**2).rewrite(log).nseries(t, 0, 2*n)
arg1 = S.NegativeOne + self.args[0]
f = arg1.as_leading_term(x)
g = (arg1 - f)/ f
res1 = sqrt(S.One + g)._eval_nseries(x, n=n, logx=logx)
res = (res1.removeO()*sqrt(f)).expand()
return ser.removeO().subs(t, res).expand().powsimp() + O(x**n, x)
if arg0 is S.NegativeOne:
t = Dummy('t', positive=True)
ser = acsc(S.NegativeOne - t**2).rewrite(log).nseries(t, 0, 2*n)
arg1 = S.NegativeOne - self.args[0]
f = arg1.as_leading_term(x)
g = (arg1 - f)/ f
res1 = sqrt(S.One + g)._eval_nseries(x, n=n, logx=logx)
res = (res1.removeO()*sqrt(f)).expand()
return ser.removeO().subs(t, res).expand().powsimp() + O(x**n, x)
res = Function._eval_nseries(self, x, n=n, logx=logx)
if arg0 is S.ComplexInfinity:
return res
if cdir != 0:
cdir = self.args[0].dir(x, cdir)
if im(cdir) < 0 and arg0.is_real and arg0 > S.Zero and arg0 < S.One:
return S.Pi - res
elif im(cdir) > 0 and arg0.is_real and arg0 < S.Zero and arg0 > S.NegativeOne:
return -S.Pi - res
return res
def _eval_rewrite_as_log(self, arg, **kwargs):
return -S.ImaginaryUnit*log(S.ImaginaryUnit/arg + sqrt(1 - 1/arg**2))
def _eval_rewrite_as_asin(self, arg, **kwargs):
return asin(1/arg)
def _eval_rewrite_as_acos(self, arg, **kwargs):
return S.Pi/2 - acos(1/arg)
def _eval_rewrite_as_atan(self, arg, **kwargs):
return sqrt(arg**2)/arg*(S.Pi/2 - atan(sqrt(arg**2 - 1)))
def _eval_rewrite_as_acot(self, arg, **kwargs):
return sqrt(arg**2)/arg*(S.Pi/2 - acot(1/sqrt(arg**2 - 1)))
def _eval_rewrite_as_asec(self, arg, **kwargs):
return S.Pi/2 - asec(arg)
class atan2(InverseTrigonometricFunction):
r"""
The function ``atan2(y, x)`` computes `\operatorname{atan}(y/x)` taking
two arguments `y` and `x`. Signs of both `y` and `x` are considered to
determine the appropriate quadrant of `\operatorname{atan}(y/x)`.
The range is `(-\pi, \pi]`. The complete definition reads as follows:
.. math::
\operatorname{atan2}(y, x) =
\begin{cases}
\arctan\left(\frac y x\right) & \qquad x > 0 \\
\arctan\left(\frac y x\right) + \pi& \qquad y \ge 0 , x < 0 \\
\arctan\left(\frac y x\right) - \pi& \qquad y < 0 , x < 0 \\
+\frac{\pi}{2} & \qquad y > 0 , x = 0 \\
-\frac{\pi}{2} & \qquad y < 0 , x = 0 \\
\text{undefined} & \qquad y = 0, x = 0
\end{cases}
Attention: Note the role reversal of both arguments. The `y`-coordinate
is the first argument and the `x`-coordinate the second.
If either `x` or `y` is complex:
.. math::
\operatorname{atan2}(y, x) =
-i\log\left(\frac{x + iy}{\sqrt{x**2 + y**2}}\right)
Examples
========
Going counter-clock wise around the origin we find the
following angles:
>>> from sympy import atan2
>>> atan2(0, 1)
0
>>> atan2(1, 1)
pi/4
>>> atan2(1, 0)
pi/2
>>> atan2(1, -1)
3*pi/4
>>> atan2(0, -1)
pi
>>> atan2(-1, -1)
-3*pi/4
>>> atan2(-1, 0)
-pi/2
>>> atan2(-1, 1)
-pi/4
which are all correct. Compare this to the results of the ordinary
`\operatorname{atan}` function for the point `(x, y) = (-1, 1)`
>>> from sympy import atan, S
>>> atan(S(1)/-1)
-pi/4
>>> atan2(1, -1)
3*pi/4
where only the `\operatorname{atan2}` function reurns what we expect.
We can differentiate the function with respect to both arguments:
>>> from sympy import diff
>>> from sympy.abc import x, y
>>> diff(atan2(y, x), x)
-y/(x**2 + y**2)
>>> diff(atan2(y, x), y)
x/(x**2 + y**2)
We can express the `\operatorname{atan2}` function in terms of
complex logarithms:
>>> from sympy import log
>>> atan2(y, x).rewrite(log)
-I*log((x + I*y)/sqrt(x**2 + y**2))
and in terms of `\operatorname(atan)`:
>>> from sympy import atan
>>> atan2(y, x).rewrite(atan)
Piecewise((2*atan(y/(x + sqrt(x**2 + y**2))), Ne(y, 0)), (pi, re(x) < 0), (0, Ne(x, 0)), (nan, True))
but note that this form is undefined on the negative real axis.
See Also
========
sin, csc, cos, sec, tan, cot
asin, acsc, acos, asec, atan, acot
References
==========
.. [1] https://en.wikipedia.org/wiki/Inverse_trigonometric_functions
.. [2] https://en.wikipedia.org/wiki/Atan2
.. [3] http://functions.wolfram.com/ElementaryFunctions/ArcTan2
"""
@classmethod
def eval(cls, y, x):
from sympy import Heaviside, im, re
if x is S.NegativeInfinity:
if y.is_zero:
# Special case y = 0 because we define Heaviside(0) = 1/2
return S.Pi
return 2*S.Pi*(Heaviside(re(y))) - S.Pi
elif x is S.Infinity:
return S.Zero
elif x.is_imaginary and y.is_imaginary and x.is_number and y.is_number:
x = im(x)
y = im(y)
if x.is_extended_real and y.is_extended_real:
if x.is_positive:
return atan(y/x)
elif x.is_negative:
if y.is_negative:
return atan(y/x) - S.Pi
elif y.is_nonnegative:
return atan(y/x) + S.Pi
elif x.is_zero:
if y.is_positive:
return S.Pi/2
elif y.is_negative:
return -S.Pi/2
elif y.is_zero:
return S.NaN
if y.is_zero:
if x.is_extended_nonzero:
return S.Pi*(S.One - Heaviside(x))
if x.is_number:
return Piecewise((S.Pi, re(x) < 0),
(0, Ne(x, 0)),
(S.NaN, True))
if x.is_number and y.is_number:
return -S.ImaginaryUnit*log(
(x + S.ImaginaryUnit*y)/sqrt(x**2 + y**2))
def _eval_rewrite_as_log(self, y, x, **kwargs):
return -S.ImaginaryUnit*log((x + S.ImaginaryUnit*y)/sqrt(x**2 + y**2))
def _eval_rewrite_as_atan(self, y, x, **kwargs):
from sympy import re
return Piecewise((2*atan(y/(x + sqrt(x**2 + y**2))), Ne(y, 0)),
(pi, re(x) < 0),
(0, Ne(x, 0)),
(S.NaN, True))
def _eval_rewrite_as_arg(self, y, x, **kwargs):
from sympy import arg
if x.is_extended_real and y.is_extended_real:
return arg(x + y*S.ImaginaryUnit)
n = x + S.ImaginaryUnit*y
d = x**2 + y**2
return arg(n/sqrt(d)) - S.ImaginaryUnit*log(abs(n)/sqrt(abs(d)))
def _eval_is_extended_real(self):
return self.args[0].is_extended_real and self.args[1].is_extended_real
def _eval_conjugate(self):
return self.func(self.args[0].conjugate(), self.args[1].conjugate())
def fdiff(self, argindex):
y, x = self.args
if argindex == 1:
# Diff wrt y
return x/(x**2 + y**2)
elif argindex == 2:
# Diff wrt x
return -y/(x**2 + y**2)
else:
raise ArgumentIndexError(self, argindex)
def _eval_evalf(self, prec):
y, x = self.args
if x.is_extended_real and y.is_extended_real:
return super()._eval_evalf(prec)
|
39722a05c3fd07cca64560754e2ec2007b8b34c7641303a501520d170cded44f | from sympy.core import Basic, S, Function, diff, Tuple, Dummy
from sympy.core.basic import as_Basic
from sympy.core.numbers import Rational, NumberSymbol
from sympy.core.relational import (Equality, Unequality, Relational,
_canonical)
from sympy.functions.elementary.miscellaneous import Max, Min
from sympy.logic.boolalg import (And, Boolean, distribute_and_over_or,
true, false, Or, ITE, simplify_logic)
from sympy.utilities.iterables import uniq, ordered, product, sift
from sympy.utilities.misc import filldedent, func_name
Undefined = S.NaN # Piecewise()
class ExprCondPair(Tuple):
"""Represents an expression, condition pair."""
def __new__(cls, expr, cond):
expr = as_Basic(expr)
if cond == True:
return Tuple.__new__(cls, expr, true)
elif cond == False:
return Tuple.__new__(cls, expr, false)
elif isinstance(cond, Basic) and cond.has(Piecewise):
cond = piecewise_fold(cond)
if isinstance(cond, Piecewise):
cond = cond.rewrite(ITE)
if not isinstance(cond, Boolean):
raise TypeError(filldedent('''
Second argument must be a Boolean,
not `%s`''' % func_name(cond)))
return Tuple.__new__(cls, expr, cond)
@property
def expr(self):
"""
Returns the expression of this pair.
"""
return self.args[0]
@property
def cond(self):
"""
Returns the condition of this pair.
"""
return self.args[1]
@property
def is_commutative(self):
return self.expr.is_commutative
def __iter__(self):
yield self.expr
yield self.cond
def _eval_simplify(self, **kwargs):
return self.func(*[a.simplify(**kwargs) for a in self.args])
class Piecewise(Function):
"""
Represents a piecewise function.
Usage:
Piecewise( (expr,cond), (expr,cond), ... )
- Each argument is a 2-tuple defining an expression and condition
- The conds are evaluated in turn returning the first that is True.
If any of the evaluated conds are not determined explicitly False,
e.g. x < 1, the function is returned in symbolic form.
- If the function is evaluated at a place where all conditions are False,
nan will be returned.
- Pairs where the cond is explicitly False, will be removed.
Examples
========
>>> from sympy import Piecewise, log, piecewise_fold
>>> from sympy.abc import x, y
>>> f = x**2
>>> g = log(x)
>>> p = Piecewise((0, x < -1), (f, x <= 1), (g, True))
>>> p.subs(x,1)
1
>>> p.subs(x,5)
log(5)
Booleans can contain Piecewise elements:
>>> cond = (x < y).subs(x, Piecewise((2, x < 0), (3, True))); cond
Piecewise((2, x < 0), (3, True)) < y
The folded version of this results in a Piecewise whose
expressions are Booleans:
>>> folded_cond = piecewise_fold(cond); folded_cond
Piecewise((2 < y, x < 0), (3 < y, True))
When a Boolean containing Piecewise (like cond) or a Piecewise
with Boolean expressions (like folded_cond) is used as a condition,
it is converted to an equivalent ITE object:
>>> Piecewise((1, folded_cond))
Piecewise((1, ITE(x < 0, y > 2, y > 3)))
When a condition is an ITE, it will be converted to a simplified
Boolean expression:
>>> piecewise_fold(_)
Piecewise((1, ((x >= 0) | (y > 2)) & ((y > 3) | (x < 0))))
See Also
========
piecewise_fold, ITE
"""
nargs = None
is_Piecewise = True
def __new__(cls, *args, **options):
if len(args) == 0:
raise TypeError("At least one (expr, cond) pair expected.")
# (Try to) sympify args first
newargs = []
for ec in args:
# ec could be a ExprCondPair or a tuple
pair = ExprCondPair(*getattr(ec, 'args', ec))
cond = pair.cond
if cond is false:
continue
newargs.append(pair)
if cond is true:
break
if options.pop('evaluate', True):
r = cls.eval(*newargs)
else:
r = None
if r is None:
return Basic.__new__(cls, *newargs, **options)
else:
return r
@classmethod
def eval(cls, *_args):
"""Either return a modified version of the args or, if no
modifications were made, return None.
Modifications that are made here:
1) relationals are made canonical
2) any False conditions are dropped
3) any repeat of a previous condition is ignored
3) any args past one with a true condition are dropped
If there are no args left, nan will be returned.
If there is a single arg with a True condition, its
corresponding expression will be returned.
"""
from sympy.functions.elementary.complexes import im, re
if not _args:
return Undefined
if len(_args) == 1 and _args[0][-1] == True:
return _args[0][0]
newargs = [] # the unevaluated conditions
current_cond = set() # the conditions up to a given e, c pair
# make conditions canonical
args = []
for e, c in _args:
if (not c.is_Atom and not isinstance(c, Relational) and
not c.has(im, re)):
free = c.free_symbols
if len(free) == 1:
funcs = [i for i in c.atoms(Function)
if not isinstance(i, Boolean)]
if len(funcs) == 1 and len(
c.xreplace({list(funcs)[0]: Dummy()}
).free_symbols) == 1:
# we can treat function like a symbol
free = funcs
_c = c
x = free.pop()
try:
c = c.as_set().as_relational(x)
except NotImplementedError:
pass
else:
reps = {}
for i in c.atoms(Relational):
ic = i.canonical
if ic.rhs in (S.Infinity, S.NegativeInfinity):
if not _c.has(ic.rhs):
# don't accept introduction of
# new Relationals with +/-oo
reps[i] = S.true
elif ('=' not in ic.rel_op and
c.xreplace({x: i.rhs}) !=
_c.xreplace({x: i.rhs})):
reps[i] = Relational(
i.lhs, i.rhs, i.rel_op + '=')
c = c.xreplace(reps)
args.append((e, _canonical(c)))
for expr, cond in args:
# Check here if expr is a Piecewise and collapse if one of
# the conds in expr matches cond. This allows the collapsing
# of Piecewise((Piecewise((x,x<0)),x<0)) to Piecewise((x,x<0)).
# This is important when using piecewise_fold to simplify
# multiple Piecewise instances having the same conds.
# Eventually, this code should be able to collapse Piecewise's
# having different intervals, but this will probably require
# using the new assumptions.
if isinstance(expr, Piecewise):
unmatching = []
for i, (e, c) in enumerate(expr.args):
if c in current_cond:
# this would already have triggered
continue
if c == cond:
if c != True:
# nothing past this condition will ever
# trigger and only those args before this
# that didn't match a previous condition
# could possibly trigger
if unmatching:
expr = Piecewise(*(
unmatching + [(e, c)]))
else:
expr = e
break
else:
unmatching.append((e, c))
# check for condition repeats
got = False
# -- if an And contains a condition that was
# already encountered, then the And will be
# False: if the previous condition was False
# then the And will be False and if the previous
# condition is True then then we wouldn't get to
# this point. In either case, we can skip this condition.
for i in ([cond] +
(list(cond.args) if isinstance(cond, And) else
[])):
if i in current_cond:
got = True
break
if got:
continue
# -- if not(c) is already in current_cond then c is
# a redundant condition in an And. This does not
# apply to Or, however: (e1, c), (e2, Or(~c, d))
# is not (e1, c), (e2, d) because if c and d are
# both False this would give no results when the
# true answer should be (e2, True)
if isinstance(cond, And):
nonredundant = []
for c in cond.args:
if (isinstance(c, Relational) and
c.negated.canonical in current_cond):
continue
nonredundant.append(c)
cond = cond.func(*nonredundant)
elif isinstance(cond, Relational):
if cond.negated.canonical in current_cond:
cond = S.true
current_cond.add(cond)
# collect successive e,c pairs when exprs or cond match
if newargs:
if newargs[-1].expr == expr:
orcond = Or(cond, newargs[-1].cond)
if isinstance(orcond, (And, Or)):
orcond = distribute_and_over_or(orcond)
newargs[-1] = ExprCondPair(expr, orcond)
continue
elif newargs[-1].cond == cond:
newargs[-1] = ExprCondPair(expr, cond)
continue
newargs.append(ExprCondPair(expr, cond))
# some conditions may have been redundant
missing = len(newargs) != len(_args)
# some conditions may have changed
same = all(a == b for a, b in zip(newargs, _args))
# if either change happened we return the expr with the
# updated args
if not newargs:
raise ValueError(filldedent('''
There are no conditions (or none that
are not trivially false) to define an
expression.'''))
if missing or not same:
return cls(*newargs)
def doit(self, **hints):
"""
Evaluate this piecewise function.
"""
newargs = []
for e, c in self.args:
if hints.get('deep', True):
if isinstance(e, Basic):
newe = e.doit(**hints)
if newe != self:
e = newe
if isinstance(c, Basic):
c = c.doit(**hints)
newargs.append((e, c))
return self.func(*newargs)
def _eval_simplify(self, **kwargs):
return piecewise_simplify(self, **kwargs)
def _eval_as_leading_term(self, x, logx=None, cdir=0):
for e, c in self.args:
if c == True or c.subs(x, 0) == True:
return e.as_leading_term(x)
def _eval_adjoint(self):
return self.func(*[(e.adjoint(), c) for e, c in self.args])
def _eval_conjugate(self):
return self.func(*[(e.conjugate(), c) for e, c in self.args])
def _eval_derivative(self, x):
return self.func(*[(diff(e, x), c) for e, c in self.args])
def _eval_evalf(self, prec):
return self.func(*[(e._evalf(prec), c) for e, c in self.args])
def piecewise_integrate(self, x, **kwargs):
"""Return the Piecewise with each expression being
replaced with its antiderivative. To obtain a continuous
antiderivative, use the `integrate` function or method.
Examples
========
>>> from sympy import Piecewise
>>> from sympy.abc import x
>>> p = Piecewise((0, x < 0), (1, x < 1), (2, True))
>>> p.piecewise_integrate(x)
Piecewise((0, x < 0), (x, x < 1), (2*x, True))
Note that this does not give a continuous function, e.g.
at x = 1 the 3rd condition applies and the antiderivative
there is 2*x so the value of the antiderivative is 2:
>>> anti = _
>>> anti.subs(x, 1)
2
The continuous derivative accounts for the integral *up to*
the point of interest, however:
>>> p.integrate(x)
Piecewise((0, x < 0), (x, x < 1), (2*x - 1, True))
>>> _.subs(x, 1)
1
See Also
========
Piecewise._eval_integral
"""
from sympy.integrals import integrate
return self.func(*[(integrate(e, x, **kwargs), c) for e, c in self.args])
def _handle_irel(self, x, handler):
"""Return either None (if the conditions of self depend only on x) else
a Piecewise expression whose expressions (handled by the handler that
was passed) are paired with the governing x-independent relationals,
e.g. Piecewise((A, a(x) & b(y)), (B, c(x) | c(y)) ->
Piecewise(
(handler(Piecewise((A, a(x) & True), (B, c(x) | True)), b(y) & c(y)),
(handler(Piecewise((A, a(x) & True), (B, c(x) | False)), b(y)),
(handler(Piecewise((A, a(x) & False), (B, c(x) | True)), c(y)),
(handler(Piecewise((A, a(x) & False), (B, c(x) | False)), True))
"""
# identify governing relationals
rel = self.atoms(Relational)
irel = list(ordered([r for r in rel if x not in r.free_symbols
and r not in (S.true, S.false)]))
if irel:
args = {}
exprinorder = []
for truth in product((1, 0), repeat=len(irel)):
reps = dict(zip(irel, truth))
# only store the true conditions since the false are implied
# when they appear lower in the Piecewise args
if 1 not in truth:
cond = None # flag this one so it doesn't get combined
else:
andargs = Tuple(*[i for i in reps if reps[i]])
free = list(andargs.free_symbols)
if len(free) == 1:
from sympy.solvers.inequalities import (
reduce_inequalities, _solve_inequality)
try:
t = reduce_inequalities(andargs, free[0])
# ValueError when there are potentially
# nonvanishing imaginary parts
except (ValueError, NotImplementedError):
# at least isolate free symbol on left
t = And(*[_solve_inequality(
a, free[0], linear=True)
for a in andargs])
else:
t = And(*andargs)
if t is S.false:
continue # an impossible combination
cond = t
expr = handler(self.xreplace(reps))
if isinstance(expr, self.func) and len(expr.args) == 1:
expr, econd = expr.args[0]
cond = And(econd, True if cond is None else cond)
# the ec pairs are being collected since all possibilities
# are being enumerated, but don't put the last one in since
# its expr might match a previous expression and it
# must appear last in the args
if cond is not None:
args.setdefault(expr, []).append(cond)
# but since we only store the true conditions we must maintain
# the order so that the expression with the most true values
# comes first
exprinorder.append(expr)
# convert collected conditions as args of Or
for k in args:
args[k] = Or(*args[k])
# take them in the order obtained
args = [(e, args[e]) for e in uniq(exprinorder)]
# add in the last arg
args.append((expr, True))
return Piecewise(*args)
def _eval_integral(self, x, _first=True, **kwargs):
"""Return the indefinite integral of the
Piecewise such that subsequent substitution of x with a
value will give the value of the integral (not including
the constant of integration) up to that point. To only
integrate the individual parts of Piecewise, use the
`piecewise_integrate` method.
Examples
========
>>> from sympy import Piecewise
>>> from sympy.abc import x
>>> p = Piecewise((0, x < 0), (1, x < 1), (2, True))
>>> p.integrate(x)
Piecewise((0, x < 0), (x, x < 1), (2*x - 1, True))
>>> p.piecewise_integrate(x)
Piecewise((0, x < 0), (x, x < 1), (2*x, True))
See Also
========
Piecewise.piecewise_integrate
"""
from sympy.integrals.integrals import integrate
if _first:
def handler(ipw):
if isinstance(ipw, self.func):
return ipw._eval_integral(x, _first=False, **kwargs)
else:
return ipw.integrate(x, **kwargs)
irv = self._handle_irel(x, handler)
if irv is not None:
return irv
# handle a Piecewise from -oo to oo with and no x-independent relationals
# -----------------------------------------------------------------------
try:
abei = self._intervals(x)
except NotImplementedError:
from sympy import Integral
return Integral(self, x) # unevaluated
pieces = [(a, b) for a, b, _, _ in abei]
oo = S.Infinity
done = [(-oo, oo, -1)]
for k, p in enumerate(pieces):
if p == (-oo, oo):
# all undone intervals will get this key
for j, (a, b, i) in enumerate(done):
if i == -1:
done[j] = a, b, k
break # nothing else to consider
N = len(done) - 1
for j, (a, b, i) in enumerate(reversed(done)):
if i == -1:
j = N - j
done[j: j + 1] = _clip(p, (a, b), k)
done = [(a, b, i) for a, b, i in done if a != b]
# append an arg if there is a hole so a reference to
# argument -1 will give Undefined
if any(i == -1 for (a, b, i) in done):
abei.append((-oo, oo, Undefined, -1))
# return the sum of the intervals
args = []
sum = None
for a, b, i in done:
anti = integrate(abei[i][-2], x, **kwargs)
if sum is None:
sum = anti
else:
sum = sum.subs(x, a)
if sum == Undefined:
sum = 0
sum += anti._eval_interval(x, a, x)
# see if we know whether b is contained in original
# condition
if b is S.Infinity:
cond = True
elif self.args[abei[i][-1]].cond.subs(x, b) == False:
cond = (x < b)
else:
cond = (x <= b)
args.append((sum, cond))
return Piecewise(*args)
def _eval_interval(self, sym, a, b, _first=True):
"""Evaluates the function along the sym in a given interval [a, b]"""
# FIXME: Currently complex intervals are not supported. A possible
# replacement algorithm, discussed in issue 5227, can be found in the
# following papers;
# http://portal.acm.org/citation.cfm?id=281649
# http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.70.4127&rep=rep1&type=pdf
from sympy.core.symbol import Dummy
if a is None or b is None:
# In this case, it is just simple substitution
return super()._eval_interval(sym, a, b)
else:
x, lo, hi = map(as_Basic, (sym, a, b))
if _first: # get only x-dependent relationals
def handler(ipw):
if isinstance(ipw, self.func):
return ipw._eval_interval(x, lo, hi, _first=None)
else:
return ipw._eval_interval(x, lo, hi)
irv = self._handle_irel(x, handler)
if irv is not None:
return irv
if (lo < hi) is S.false or (
lo is S.Infinity or hi is S.NegativeInfinity):
rv = self._eval_interval(x, hi, lo, _first=False)
if isinstance(rv, Piecewise):
rv = Piecewise(*[(-e, c) for e, c in rv.args])
else:
rv = -rv
return rv
if (lo < hi) is S.true or (
hi is S.Infinity or lo is S.NegativeInfinity):
pass
else:
_a = Dummy('lo')
_b = Dummy('hi')
a = lo if lo.is_comparable else _a
b = hi if hi.is_comparable else _b
pos = self._eval_interval(x, a, b, _first=False)
if a == _a and b == _b:
# it's purely symbolic so just swap lo and hi and
# change the sign to get the value for when lo > hi
neg, pos = (-pos.xreplace({_a: hi, _b: lo}),
pos.xreplace({_a: lo, _b: hi}))
else:
# at least one of the bounds was comparable, so allow
# _eval_interval to use that information when computing
# the interval with lo and hi reversed
neg, pos = (-self._eval_interval(x, hi, lo, _first=False),
pos.xreplace({_a: lo, _b: hi}))
# allow simplification based on ordering of lo and hi
p = Dummy('', positive=True)
if lo.is_Symbol:
pos = pos.xreplace({lo: hi - p}).xreplace({p: hi - lo})
neg = neg.xreplace({lo: hi + p}).xreplace({p: lo - hi})
elif hi.is_Symbol:
pos = pos.xreplace({hi: lo + p}).xreplace({p: hi - lo})
neg = neg.xreplace({hi: lo - p}).xreplace({p: lo - hi})
# evaluate limits that may have unevaluate Min/Max
touch = lambda _: _.replace(
lambda x: isinstance(x, (Min, Max)),
lambda x: x.func(*x.args))
neg = touch(neg)
pos = touch(pos)
# assemble return expression; make the first condition be Lt
# b/c then the first expression will look the same whether
# the lo or hi limit is symbolic
if a == _a: # the lower limit was symbolic
rv = Piecewise(
(pos,
lo < hi),
(neg,
True))
else:
rv = Piecewise(
(neg,
hi < lo),
(pos,
True))
if rv == Undefined:
raise ValueError("Can't integrate across undefined region.")
if any(isinstance(i, Piecewise) for i in (pos, neg)):
rv = piecewise_fold(rv)
return rv
# handle a Piecewise with lo <= hi and no x-independent relationals
# -----------------------------------------------------------------
try:
abei = self._intervals(x)
except NotImplementedError:
from sympy import Integral
# not being able to do the interval of f(x) can
# be stated as not being able to do the integral
# of f'(x) over the same range
return Integral(self.diff(x), (x, lo, hi)) # unevaluated
pieces = [(a, b) for a, b, _, _ in abei]
done = [(lo, hi, -1)]
oo = S.Infinity
for k, p in enumerate(pieces):
if p[:2] == (-oo, oo):
# all undone intervals will get this key
for j, (a, b, i) in enumerate(done):
if i == -1:
done[j] = a, b, k
break # nothing else to consider
N = len(done) - 1
for j, (a, b, i) in enumerate(reversed(done)):
if i == -1:
j = N - j
done[j: j + 1] = _clip(p, (a, b), k)
done = [(a, b, i) for a, b, i in done if a != b]
# return the sum of the intervals
sum = S.Zero
upto = None
for a, b, i in done:
if i == -1:
if upto is None:
return Undefined
# TODO simplify hi <= upto
return Piecewise((sum, hi <= upto), (Undefined, True))
sum += abei[i][-2]._eval_interval(x, a, b)
upto = b
return sum
def _intervals(self, sym):
"""Return a list of unique tuples, (a, b, e, i), where a and b
are the lower and upper bounds in which the expression e of
argument i in self is defined and a < b (when involving
numbers) or a <= b when involving symbols.
If there are any relationals not involving sym, or any
relational cannot be solved for sym, NotImplementedError is
raised. The calling routine should have removed such
relationals before calling this routine.
The evaluated conditions will be returned as ranges.
Discontinuous ranges will be returned separately with
identical expressions. The first condition that evaluates to
True will be returned as the last tuple with a, b = -oo, oo.
"""
from sympy.solvers.inequalities import _solve_inequality
from sympy.logic.boolalg import to_cnf, distribute_or_over_and
assert isinstance(self, Piecewise)
def _solve_relational(r):
if sym not in r.free_symbols:
nonsymfail(r)
rv = _solve_inequality(r, sym)
if isinstance(rv, Relational):
free = rv.args[1].free_symbols
if rv.args[0] != sym or sym in free:
raise NotImplementedError(filldedent('''
Unable to solve relational
%s for %s.''' % (r, sym)))
if rv.rel_op == '==':
# this equality has been affirmed to have the form
# Eq(sym, rhs) where rhs is sym-free; it represents
# a zero-width interval which will be ignored
# whether it is an isolated condition or contained
# within an And or an Or
rv = S.false
elif rv.rel_op == '!=':
try:
rv = Or(sym < rv.rhs, sym > rv.rhs)
except TypeError:
# e.g. x != I ==> all real x satisfy
rv = S.true
elif rv == (S.NegativeInfinity < sym) & (sym < S.Infinity):
rv = S.true
return rv
def nonsymfail(cond):
raise NotImplementedError(filldedent('''
A condition not involving
%s appeared: %s''' % (sym, cond)))
# make self canonical wrt Relationals
reps = {
r: _solve_relational(r) for r in self.atoms(Relational)}
# process args individually so if any evaluate, their position
# in the original Piecewise will be known
args = [i.xreplace(reps) for i in self.args]
# precondition args
expr_cond = []
default = idefault = None
for i, (expr, cond) in enumerate(args):
if cond is S.false:
continue
elif cond is S.true:
default = expr
idefault = i
break
cond = to_cnf(cond)
if isinstance(cond, And):
cond = distribute_or_over_and(cond)
if isinstance(cond, Or):
expr_cond.extend(
[(i, expr, o) for o in cond.args
if not isinstance(o, Equality)])
elif cond is not S.false:
expr_cond.append((i, expr, cond))
# determine intervals represented by conditions
int_expr = []
for iarg, expr, cond in expr_cond:
if isinstance(cond, And):
lower = S.NegativeInfinity
upper = S.Infinity
exclude = []
for cond2 in cond.args:
if isinstance(cond2, Equality):
lower = upper # ignore
break
elif isinstance(cond2, Unequality):
l, r = cond2.args
if l == sym:
exclude.append(r)
elif r == sym:
exclude.append(l)
else:
nonsymfail(cond2)
continue
elif cond2.lts == sym:
upper = Min(cond2.gts, upper)
elif cond2.gts == sym:
lower = Max(cond2.lts, lower)
else:
nonsymfail(cond2) # should never get here
if exclude:
exclude = list(ordered(exclude))
newcond = []
for i, e in enumerate(exclude):
if e < lower == True or e > upper == True:
continue
if not newcond:
newcond.append((None, lower)) # add a primer
newcond.append((newcond[-1][1], e))
newcond.append((newcond[-1][1], upper))
newcond.pop(0) # remove the primer
expr_cond.extend([(iarg, expr, And(i[0] < sym, sym < i[1])) for i in newcond])
continue
elif isinstance(cond, Relational):
lower, upper = cond.lts, cond.gts # part 1: initialize with givens
if cond.lts == sym: # part 1a: expand the side ...
lower = S.NegativeInfinity # e.g. x <= 0 ---> -oo <= 0
elif cond.gts == sym: # part 1a: ... that can be expanded
upper = S.Infinity # e.g. x >= 0 ---> oo >= 0
else:
nonsymfail(cond)
else:
raise NotImplementedError(
'unrecognized condition: %s' % cond)
lower, upper = lower, Max(lower, upper)
if (lower >= upper) is not S.true:
int_expr.append((lower, upper, expr, iarg))
if default is not None:
int_expr.append(
(S.NegativeInfinity, S.Infinity, default, idefault))
return list(uniq(int_expr))
def _eval_nseries(self, x, n, logx, cdir=0):
args = [(ec.expr._eval_nseries(x, n, logx), ec.cond) for ec in self.args]
return self.func(*args)
def _eval_power(self, s):
return self.func(*[(e**s, c) for e, c in self.args])
def _eval_subs(self, old, new):
# this is strictly not necessary, but we can keep track
# of whether True or False conditions arise and be
# somewhat more efficient by avoiding other substitutions
# and avoiding invalid conditions that appear after a
# True condition
args = list(self.args)
args_exist = False
for i, (e, c) in enumerate(args):
c = c._subs(old, new)
if c != False:
args_exist = True
e = e._subs(old, new)
args[i] = (e, c)
if c == True:
break
if not args_exist:
args = ((Undefined, True),)
return self.func(*args)
def _eval_transpose(self):
return self.func(*[(e.transpose(), c) for e, c in self.args])
def _eval_template_is_attr(self, is_attr):
b = None
for expr, _ in self.args:
a = getattr(expr, is_attr)
if a is None:
return
if b is None:
b = a
elif b is not a:
return
return b
_eval_is_finite = lambda self: self._eval_template_is_attr(
'is_finite')
_eval_is_complex = lambda self: self._eval_template_is_attr('is_complex')
_eval_is_even = lambda self: self._eval_template_is_attr('is_even')
_eval_is_imaginary = lambda self: self._eval_template_is_attr(
'is_imaginary')
_eval_is_integer = lambda self: self._eval_template_is_attr('is_integer')
_eval_is_irrational = lambda self: self._eval_template_is_attr(
'is_irrational')
_eval_is_negative = lambda self: self._eval_template_is_attr('is_negative')
_eval_is_nonnegative = lambda self: self._eval_template_is_attr(
'is_nonnegative')
_eval_is_nonpositive = lambda self: self._eval_template_is_attr(
'is_nonpositive')
_eval_is_nonzero = lambda self: self._eval_template_is_attr(
'is_nonzero')
_eval_is_odd = lambda self: self._eval_template_is_attr('is_odd')
_eval_is_polar = lambda self: self._eval_template_is_attr('is_polar')
_eval_is_positive = lambda self: self._eval_template_is_attr('is_positive')
_eval_is_extended_real = lambda self: self._eval_template_is_attr(
'is_extended_real')
_eval_is_extended_positive = lambda self: self._eval_template_is_attr(
'is_extended_positive')
_eval_is_extended_negative = lambda self: self._eval_template_is_attr(
'is_extended_negative')
_eval_is_extended_nonzero = lambda self: self._eval_template_is_attr(
'is_extended_nonzero')
_eval_is_extended_nonpositive = lambda self: self._eval_template_is_attr(
'is_extended_nonpositive')
_eval_is_extended_nonnegative = lambda self: self._eval_template_is_attr(
'is_extended_nonnegative')
_eval_is_real = lambda self: self._eval_template_is_attr('is_real')
_eval_is_zero = lambda self: self._eval_template_is_attr(
'is_zero')
@classmethod
def __eval_cond(cls, cond):
"""Return the truth value of the condition."""
if cond == True:
return True
if isinstance(cond, Equality):
try:
diff = cond.lhs - cond.rhs
if diff.is_commutative:
return diff.is_zero
except TypeError:
pass
def as_expr_set_pairs(self, domain=None):
"""Return tuples for each argument of self that give
the expression and the interval in which it is valid
which is contained within the given domain.
If a condition cannot be converted to a set, an error
will be raised. The variable of the conditions is
assumed to be real; sets of real values are returned.
Examples
========
>>> from sympy import Piecewise, Interval
>>> from sympy.abc import x
>>> p = Piecewise(
... (1, x < 2),
... (2,(x > 0) & (x < 4)),
... (3, True))
>>> p.as_expr_set_pairs()
[(1, Interval.open(-oo, 2)),
(2, Interval.Ropen(2, 4)),
(3, Interval(4, oo))]
>>> p.as_expr_set_pairs(Interval(0, 3))
[(1, Interval.Ropen(0, 2)),
(2, Interval(2, 3))]
"""
if domain is None:
domain = S.Reals
exp_sets = []
U = domain
complex = not domain.is_subset(S.Reals)
cond_free = set()
for expr, cond in self.args:
cond_free |= cond.free_symbols
if len(cond_free) > 1:
raise NotImplementedError(filldedent('''
multivariate conditions are not handled.'''))
if complex:
for i in cond.atoms(Relational):
if not isinstance(i, (Equality, Unequality)):
raise ValueError(filldedent('''
Inequalities in the complex domain are
not supported. Try the real domain by
setting domain=S.Reals'''))
cond_int = U.intersect(cond.as_set())
U = U - cond_int
if cond_int != S.EmptySet:
exp_sets.append((expr, cond_int))
return exp_sets
def _eval_rewrite_as_ITE(self, *args, **kwargs):
byfree = {}
args = list(args)
default = any(c == True for b, c in args)
for i, (b, c) in enumerate(args):
if not isinstance(b, Boolean) and b != True:
raise TypeError(filldedent('''
Expecting Boolean or bool but got `%s`
''' % func_name(b)))
if c == True:
break
# loop over independent conditions for this b
for c in c.args if isinstance(c, Or) else [c]:
free = c.free_symbols
x = free.pop()
try:
byfree[x] = byfree.setdefault(
x, S.EmptySet).union(c.as_set())
except NotImplementedError:
if not default:
raise NotImplementedError(filldedent('''
A method to determine whether a multivariate
conditional is consistent with a complete coverage
of all variables has not been implemented so the
rewrite is being stopped after encountering `%s`.
This error would not occur if a default expression
like `(foo, True)` were given.
''' % c))
if byfree[x] in (S.UniversalSet, S.Reals):
# collapse the ith condition to True and break
args[i] = list(args[i])
c = args[i][1] = True
break
if c == True:
break
if c != True:
raise ValueError(filldedent('''
Conditions must cover all reals or a final default
condition `(foo, True)` must be given.
'''))
last, _ = args[i] # ignore all past ith arg
for a, c in reversed(args[:i]):
last = ITE(c, a, last)
return _canonical(last)
def _eval_rewrite_as_KroneckerDelta(self, *args):
from sympy import Ne, Eq, Not, KroneckerDelta
rules = {
And: [False, False],
Or: [True, True],
Not: [True, False],
Eq: [None, None],
Ne: [None, None]
}
class UnrecognizedCondition(Exception):
pass
def rewrite(cond):
if isinstance(cond, Eq):
return KroneckerDelta(*cond.args)
if isinstance(cond, Ne):
return 1 - KroneckerDelta(*cond.args)
cls, args = type(cond), cond.args
if cls not in rules:
raise UnrecognizedCondition(cls)
b1, b2 = rules[cls]
k = 1
for c in args:
if b1:
k *= 1 - rewrite(c)
else:
k *= rewrite(c)
if b2:
return 1 - k
return k
conditions = []
true_value = None
for value, cond in args:
if type(cond) in rules:
conditions.append((value, cond))
elif cond is S.true:
if true_value is None:
true_value = value
else:
return
if true_value is not None:
result = true_value
for value, cond in conditions[::-1]:
try:
k = rewrite(cond)
result = k * value + (1 - k) * result
except UnrecognizedCondition:
return
return result
def piecewise_fold(expr):
"""
Takes an expression containing a piecewise function and returns the
expression in piecewise form. In addition, any ITE conditions are
rewritten in negation normal form and simplified.
Examples
========
>>> from sympy import Piecewise, piecewise_fold, sympify as S
>>> from sympy.abc import x
>>> p = Piecewise((x, x < 1), (1, S(1) <= x))
>>> piecewise_fold(x*p)
Piecewise((x**2, x < 1), (x, True))
See Also
========
Piecewise
"""
if not isinstance(expr, Basic) or not expr.has(Piecewise):
return expr
new_args = []
if isinstance(expr, (ExprCondPair, Piecewise)):
for e, c in expr.args:
if not isinstance(e, Piecewise):
e = piecewise_fold(e)
# we don't keep Piecewise in condition because
# it has to be checked to see that it's complete
# and we convert it to ITE at that time
assert not c.has(Piecewise) # pragma: no cover
if isinstance(c, ITE):
c = c.to_nnf()
c = simplify_logic(c, form='cnf')
if isinstance(e, Piecewise):
new_args.extend([(piecewise_fold(ei), And(ci, c))
for ei, ci in e.args])
else:
new_args.append((e, c))
else:
from sympy.utilities.iterables import cartes, sift, common_prefix
# Given
# P1 = Piecewise((e11, c1), (e12, c2), A)
# P2 = Piecewise((e21, c1), (e22, c2), B)
# ...
# the folding of f(P1, P2) is trivially
# Piecewise(
# (f(e11, e21), c1),
# (f(e12, e22), c2),
# (f(Piecewise(A), Piecewise(B)), True))
# Certain objects end up rewriting themselves as thus, so
# we do that grouping before the more generic folding.
# The following applies this idea when f = Add or f = Mul
# (and the expression is commutative).
if expr.is_Add or expr.is_Mul and expr.is_commutative:
p, args = sift(expr.args, lambda x: x.is_Piecewise, binary=True)
pc = sift(p, lambda x: tuple([c for e,c in x.args]))
for c in list(ordered(pc)):
if len(pc[c]) > 1:
pargs = [list(i.args) for i in pc[c]]
# the first one is the same; there may be more
com = common_prefix(*[
[i.cond for i in j] for j in pargs])
n = len(com)
collected = []
for i in range(n):
collected.append((
expr.func(*[ai[i].expr for ai in pargs]),
com[i]))
remains = []
for a in pargs:
if n == len(a): # no more args
continue
if a[n].cond == True: # no longer Piecewise
remains.append(a[n].expr)
else: # restore the remaining Piecewise
remains.append(
Piecewise(*a[n:], evaluate=False))
if remains:
collected.append((expr.func(*remains), True))
args.append(Piecewise(*collected, evaluate=False))
continue
args.extend(pc[c])
else:
args = expr.args
# fold
folded = list(map(piecewise_fold, args))
for ec in cartes(*[
(i.args if isinstance(i, Piecewise) else
[(i, true)]) for i in folded]):
e, c = zip(*ec)
new_args.append((expr.func(*e), And(*c)))
return Piecewise(*new_args)
def _clip(A, B, k):
"""Return interval B as intervals that are covered by A (keyed
to k) and all other intervals of B not covered by A keyed to -1.
The reference point of each interval is the rhs; if the lhs is
greater than the rhs then an interval of zero width interval will
result, e.g. (4, 1) is treated like (1, 1).
Examples
========
>>> from sympy.functions.elementary.piecewise import _clip
>>> from sympy import Tuple
>>> A = Tuple(1, 3)
>>> B = Tuple(2, 4)
>>> _clip(A, B, 0)
[(2, 3, 0), (3, 4, -1)]
Interpretation: interval portion (2, 3) of interval (2, 4) is
covered by interval (1, 3) and is keyed to 0 as requested;
interval (3, 4) was not covered by (1, 3) and is keyed to -1.
"""
a, b = B
c, d = A
c, d = Min(Max(c, a), b), Min(Max(d, a), b)
a, b = Min(a, b), b
p = []
if a != c:
p.append((a, c, -1))
else:
pass
if c != d:
p.append((c, d, k))
else:
pass
if b != d:
if d == c and p and p[-1][-1] == -1:
p[-1] = p[-1][0], b, -1
else:
p.append((d, b, -1))
else:
pass
return p
def piecewise_simplify_arguments(expr, **kwargs):
from sympy import simplify
args = []
for e, c in expr.args:
if isinstance(e, Basic):
doit = kwargs.pop('doit', None)
# Skip doit to avoid growth at every call for some integrals
# and sums, see sympy/sympy#17165
newe = simplify(e, doit=False, **kwargs)
if newe != expr:
e = newe
if isinstance(c, Basic):
c = simplify(c, doit=doit, **kwargs)
args.append((e, c))
return Piecewise(*args)
def piecewise_simplify(expr, **kwargs):
expr = piecewise_simplify_arguments(expr, **kwargs)
if not isinstance(expr, Piecewise):
return expr
args = list(expr.args)
_blessed = lambda e: getattr(e.lhs, '_diff_wrt', False) and (
getattr(e.rhs, '_diff_wrt', None) or
isinstance(e.rhs, (Rational, NumberSymbol)))
for i, (expr, cond) in enumerate(args):
# try to simplify conditions and the expression for
# equalities that are part of the condition, e.g.
# Piecewise((n, And(Eq(n,0), Eq(n + m, 0))), (1, True))
# -> Piecewise((0, And(Eq(n, 0), Eq(m, 0))), (1, True))
if isinstance(cond, And):
eqs, other = sift(cond.args,
lambda i: isinstance(i, Equality), binary=True)
elif isinstance(cond, Equality):
eqs, other = [cond], []
else:
eqs = other = []
if eqs:
eqs = list(ordered(eqs))
for j, e in enumerate(eqs):
# these blessed lhs objects behave like Symbols
# and the rhs are simple replacements for the "symbols"
if _blessed(e):
expr = expr.subs(*e.args)
eqs[j + 1:] = [ei.subs(*e.args) for ei in eqs[j + 1:]]
other = [ei.subs(*e.args) for ei in other]
cond = And(*(eqs + other))
args[i] = args[i].func(expr, cond)
# See if expressions valid for an Equal expression happens to evaluate
# to the same function as in the next piecewise segment, see:
# https://github.com/sympy/sympy/issues/8458
prevexpr = None
for i, (expr, cond) in reversed(list(enumerate(args))):
if prevexpr is not None:
if isinstance(cond, And):
eqs, other = sift(cond.args,
lambda i: isinstance(i, Equality), binary=True)
elif isinstance(cond, Equality):
eqs, other = [cond], []
else:
eqs = other = []
_prevexpr = prevexpr
_expr = expr
if eqs and not other:
eqs = list(ordered(eqs))
for e in eqs:
# allow 2 args to collapse into 1 for any e
# otherwise limit simplification to only simple-arg
# Eq instances
if len(args) == 2 or _blessed(e):
_prevexpr = _prevexpr.subs(*e.args)
_expr = _expr.subs(*e.args)
# Did it evaluate to the same?
if _prevexpr == _expr:
# Set the expression for the Not equal section to the same
# as the next. These will be merged when creating the new
# Piecewise
args[i] = args[i].func(args[i+1][0], cond)
else:
# Update the expression that we compare against
prevexpr = expr
else:
prevexpr = expr
return Piecewise(*args)
|
e5bdb3cebacf7e622b70c3c0688ba29eb44136d90cf1443a4c6fa141b08e415c | from sympy import Basic, Expr
from sympy.core import Add, S
from sympy.core.evalf import get_integer_part, PrecisionExhausted
from sympy.core.function import Function
from sympy.core.logic import fuzzy_or
from sympy.core.numbers import Integer
from sympy.core.relational import Gt, Lt, Ge, Le, Relational, is_eq
from sympy.core.symbol import Symbol
from sympy.core.sympify import _sympify
from sympy.multipledispatch import dispatch
###############################################################################
######################### FLOOR and CEILING FUNCTIONS #########################
###############################################################################
class RoundFunction(Function):
"""The base class for rounding functions."""
@classmethod
def eval(cls, arg):
from sympy import im
v = cls._eval_number(arg)
if v is not None:
return v
if arg.is_integer or arg.is_finite is False:
return arg
if arg.is_imaginary or (S.ImaginaryUnit*arg).is_real:
i = im(arg)
if not i.has(S.ImaginaryUnit):
return cls(i)*S.ImaginaryUnit
return cls(arg, evaluate=False)
# Integral, numerical, symbolic part
ipart = npart = spart = S.Zero
# Extract integral (or complex integral) terms
terms = Add.make_args(arg)
for t in terms:
if t.is_integer or (t.is_imaginary and im(t).is_integer):
ipart += t
elif t.has(Symbol):
spart += t
else:
npart += t
if not (npart or spart):
return ipart
# Evaluate npart numerically if independent of spart
if npart and (
not spart or
npart.is_real and (spart.is_imaginary or (S.ImaginaryUnit*spart).is_real) or
npart.is_imaginary and spart.is_real):
try:
r, i = get_integer_part(
npart, cls._dir, {}, return_ints=True)
ipart += Integer(r) + Integer(i)*S.ImaginaryUnit
npart = S.Zero
except (PrecisionExhausted, NotImplementedError):
pass
spart += npart
if not spart:
return ipart
elif spart.is_imaginary or (S.ImaginaryUnit*spart).is_real:
return ipart + cls(im(spart), evaluate=False)*S.ImaginaryUnit
elif isinstance(spart, (floor, ceiling)):
return ipart + spart
else:
return ipart + cls(spart, evaluate=False)
def _eval_is_finite(self):
return self.args[0].is_finite
def _eval_is_real(self):
return self.args[0].is_real
def _eval_is_integer(self):
return self.args[0].is_real
class floor(RoundFunction):
"""
Floor is a univariate function which returns the largest integer
value not greater than its argument. This implementation
generalizes floor to complex numbers by taking the floor of the
real and imaginary parts separately.
Examples
========
>>> from sympy import floor, E, I, S, Float, Rational
>>> floor(17)
17
>>> floor(Rational(23, 10))
2
>>> floor(2*E)
5
>>> floor(-Float(0.567))
-1
>>> floor(-I/2)
-I
>>> floor(S(5)/2 + 5*I/2)
2 + 2*I
See Also
========
sympy.functions.elementary.integers.ceiling
References
==========
.. [1] "Concrete mathematics" by Graham, pp. 87
.. [2] http://mathworld.wolfram.com/FloorFunction.html
"""
_dir = -1
@classmethod
def _eval_number(cls, arg):
if arg.is_Number:
return arg.floor()
elif any(isinstance(i, j)
for i in (arg, -arg) for j in (floor, ceiling)):
return arg
if arg.is_NumberSymbol:
return arg.approximation_interval(Integer)[0]
def _eval_as_leading_term(self, x, logx=None, cdir=0):
arg = self.args[0]
arg0 = arg.subs(x, 0)
r = self.subs(x, 0)
if arg0.is_finite:
if arg0 == r:
if cdir == 0:
ndirl = arg.dir(x, cdir=-1)
ndir = arg.dir(x, cdir=1)
if ndir != ndirl:
raise ValueError("Two sided limit of %s around 0"
"does not exist" % self)
else:
ndir = arg.dir(x, cdir=cdir)
return r - 1 if ndir.is_negative else r
else:
return r
return arg.as_leading_term(x, logx=logx, cdir=cdir)
def _eval_nseries(self, x, n, logx, cdir=0):
arg = self.args[0]
arg0 = arg.subs(x, 0)
if arg0.is_infinite:
from sympy.calculus.util import AccumBounds
from sympy.series.order import Order
s = arg._eval_nseries(x, n, logx, cdir)
o = Order(1, (x, 0)) if n <= 0 else AccumBounds(-1, 0)
return s + o
r = self.subs(x, 0)
if arg0 == r:
ndir = arg.dir(x, cdir=cdir if cdir != 0 else 1)
return r - 1 if ndir.is_negative else r
else:
return r
def _eval_is_negative(self):
return self.args[0].is_negative
def _eval_is_nonnegative(self):
return self.args[0].is_nonnegative
def _eval_rewrite_as_ceiling(self, arg, **kwargs):
return -ceiling(-arg)
def _eval_rewrite_as_frac(self, arg, **kwargs):
return arg - frac(arg)
def __le__(self, other):
other = S(other)
if self.args[0].is_real:
if other.is_integer:
return self.args[0] < other + 1
if other.is_number and other.is_real:
return self.args[0] < ceiling(other)
if self.args[0] == other and other.is_real:
return S.true
if other is S.Infinity and self.is_finite:
return S.true
return Le(self, other, evaluate=False)
def __ge__(self, other):
other = S(other)
if self.args[0].is_real:
if other.is_integer:
return self.args[0] >= other
if other.is_number and other.is_real:
return self.args[0] >= ceiling(other)
if self.args[0] == other and other.is_real:
return S.false
if other is S.NegativeInfinity and self.is_finite:
return S.true
return Ge(self, other, evaluate=False)
def __gt__(self, other):
other = S(other)
if self.args[0].is_real:
if other.is_integer:
return self.args[0] >= other + 1
if other.is_number and other.is_real:
return self.args[0] >= ceiling(other)
if self.args[0] == other and other.is_real:
return S.false
if other is S.NegativeInfinity and self.is_finite:
return S.true
return Gt(self, other, evaluate=False)
def __lt__(self, other):
other = S(other)
if self.args[0].is_real:
if other.is_integer:
return self.args[0] < other
if other.is_number and other.is_real:
return self.args[0] < ceiling(other)
if self.args[0] == other and other.is_real:
return S.false
if other is S.Infinity and self.is_finite:
return S.true
return Lt(self, other, evaluate=False)
@dispatch(floor, Expr)
def _eval_is_eq(lhs, rhs): # noqa:F811
return is_eq(lhs.rewrite(ceiling), rhs) or \
is_eq(lhs.rewrite(frac),rhs)
class ceiling(RoundFunction):
"""
Ceiling is a univariate function which returns the smallest integer
value not less than its argument. This implementation
generalizes ceiling to complex numbers by taking the ceiling of the
real and imaginary parts separately.
Examples
========
>>> from sympy import ceiling, E, I, S, Float, Rational
>>> ceiling(17)
17
>>> ceiling(Rational(23, 10))
3
>>> ceiling(2*E)
6
>>> ceiling(-Float(0.567))
0
>>> ceiling(I/2)
I
>>> ceiling(S(5)/2 + 5*I/2)
3 + 3*I
See Also
========
sympy.functions.elementary.integers.floor
References
==========
.. [1] "Concrete mathematics" by Graham, pp. 87
.. [2] http://mathworld.wolfram.com/CeilingFunction.html
"""
_dir = 1
@classmethod
def _eval_number(cls, arg):
if arg.is_Number:
return arg.ceiling()
elif any(isinstance(i, j)
for i in (arg, -arg) for j in (floor, ceiling)):
return arg
if arg.is_NumberSymbol:
return arg.approximation_interval(Integer)[1]
def _eval_as_leading_term(self, x, logx=None, cdir=0):
arg = self.args[0]
arg0 = arg.subs(x, 0)
r = self.subs(x, 0)
if arg0.is_finite:
if arg0 == r:
if cdir == 0:
ndirl = arg.dir(x, cdir=-1)
ndir = arg.dir(x, cdir=1)
if ndir != ndirl:
raise ValueError("Two sided limit of %s around 0"
"does not exist" % self)
else:
ndir = arg.dir(x, cdir=cdir)
return r if ndir.is_negative else r + 1
else:
return r
return arg.as_leading_term(x, logx=logx, cdir=cdir)
def _eval_nseries(self, x, n, logx, cdir=0):
arg = self.args[0]
arg0 = arg.subs(x, 0)
if arg0.is_infinite:
from sympy.calculus.util import AccumBounds
from sympy.series.order import Order
s = arg._eval_nseries(x, n, logx, cdir)
o = Order(1, (x, 0)) if n <= 0 else AccumBounds(0, 1)
return s + o
r = self.subs(x, 0)
if arg0 == r:
ndir = arg.dir(x, cdir=cdir if cdir != 0 else 1)
return r if ndir.is_negative else r + 1
else:
return r
def _eval_rewrite_as_floor(self, arg, **kwargs):
return -floor(-arg)
def _eval_rewrite_as_frac(self, arg, **kwargs):
return arg + frac(-arg)
def _eval_is_positive(self):
return self.args[0].is_positive
def _eval_is_nonpositive(self):
return self.args[0].is_nonpositive
def __lt__(self, other):
other = S(other)
if self.args[0].is_real:
if other.is_integer:
return self.args[0] <= other - 1
if other.is_number and other.is_real:
return self.args[0] <= floor(other)
if self.args[0] == other and other.is_real:
return S.false
if other is S.Infinity and self.is_finite:
return S.true
return Lt(self, other, evaluate=False)
def __gt__(self, other):
other = S(other)
if self.args[0].is_real:
if other.is_integer:
return self.args[0] > other
if other.is_number and other.is_real:
return self.args[0] > floor(other)
if self.args[0] == other and other.is_real:
return S.false
if other is S.NegativeInfinity and self.is_finite:
return S.true
return Gt(self, other, evaluate=False)
def __ge__(self, other):
other = S(other)
if self.args[0].is_real:
if other.is_integer:
return self.args[0] > other - 1
if other.is_number and other.is_real:
return self.args[0] > floor(other)
if self.args[0] == other and other.is_real:
return S.true
if other is S.NegativeInfinity and self.is_finite:
return S.true
return Ge(self, other, evaluate=False)
def __le__(self, other):
other = S(other)
if self.args[0].is_real:
if other.is_integer:
return self.args[0] <= other
if other.is_number and other.is_real:
return self.args[0] <= floor(other)
if self.args[0] == other and other.is_real:
return S.false
if other is S.Infinity and self.is_finite:
return S.true
return Le(self, other, evaluate=False)
@dispatch(ceiling, Basic) # type:ignore
def _eval_is_eq(lhs, rhs): # noqa:F811
return is_eq(lhs.rewrite(floor), rhs) or is_eq(lhs.rewrite(frac),rhs)
class frac(Function):
r"""Represents the fractional part of x
For real numbers it is defined [1]_ as
.. math::
x - \left\lfloor{x}\right\rfloor
Examples
========
>>> from sympy import Symbol, frac, Rational, floor, I
>>> frac(Rational(4, 3))
1/3
>>> frac(-Rational(4, 3))
2/3
returns zero for integer arguments
>>> n = Symbol('n', integer=True)
>>> frac(n)
0
rewrite as floor
>>> x = Symbol('x')
>>> frac(x).rewrite(floor)
x - floor(x)
for complex arguments
>>> r = Symbol('r', real=True)
>>> t = Symbol('t', real=True)
>>> frac(t + I*r)
I*frac(r) + frac(t)
See Also
========
sympy.functions.elementary.integers.floor
sympy.functions.elementary.integers.ceiling
References
===========
.. [1] https://en.wikipedia.org/wiki/Fractional_part
.. [2] http://mathworld.wolfram.com/FractionalPart.html
"""
@classmethod
def eval(cls, arg):
from sympy import AccumBounds, im
def _eval(arg):
if arg is S.Infinity or arg is S.NegativeInfinity:
return AccumBounds(0, 1)
if arg.is_integer:
return S.Zero
if arg.is_number:
if arg is S.NaN:
return S.NaN
elif arg is S.ComplexInfinity:
return S.NaN
else:
return arg - floor(arg)
return cls(arg, evaluate=False)
terms = Add.make_args(arg)
real, imag = S.Zero, S.Zero
for t in terms:
# Two checks are needed for complex arguments
# see issue-7649 for details
if t.is_imaginary or (S.ImaginaryUnit*t).is_real:
i = im(t)
if not i.has(S.ImaginaryUnit):
imag += i
else:
real += t
else:
real += t
real = _eval(real)
imag = _eval(imag)
return real + S.ImaginaryUnit*imag
def _eval_rewrite_as_floor(self, arg, **kwargs):
return arg - floor(arg)
def _eval_rewrite_as_ceiling(self, arg, **kwargs):
return arg + ceiling(-arg)
def _eval_is_finite(self):
return True
def _eval_is_real(self):
return self.args[0].is_extended_real
def _eval_is_imaginary(self):
return self.args[0].is_imaginary
def _eval_is_integer(self):
return self.args[0].is_integer
def _eval_is_zero(self):
return fuzzy_or([self.args[0].is_zero, self.args[0].is_integer])
def _eval_is_negative(self):
return False
def __ge__(self, other):
if self.is_extended_real:
other = _sympify(other)
# Check if other <= 0
if other.is_extended_nonpositive:
return S.true
# Check if other >= 1
res = self._value_one_or_more(other)
if res is not None:
return not(res)
return Ge(self, other, evaluate=False)
def __gt__(self, other):
if self.is_extended_real:
other = _sympify(other)
# Check if other < 0
res = self._value_one_or_more(other)
if res is not None:
return not(res)
# Check if other >= 1
if other.is_extended_negative:
return S.true
return Gt(self, other, evaluate=False)
def __le__(self, other):
if self.is_extended_real:
other = _sympify(other)
# Check if other < 0
if other.is_extended_negative:
return S.false
# Check if other >= 1
res = self._value_one_or_more(other)
if res is not None:
return res
return Le(self, other, evaluate=False)
def __lt__(self, other):
if self.is_extended_real:
other = _sympify(other)
# Check if other <= 0
if other.is_extended_nonpositive:
return S.false
# Check if other >= 1
res = self._value_one_or_more(other)
if res is not None:
return res
return Lt(self, other, evaluate=False)
def _value_one_or_more(self, other):
if other.is_extended_real:
if other.is_number:
res = other >= 1
if res and not isinstance(res, Relational):
return S.true
if other.is_integer and other.is_positive:
return S.true
@dispatch(frac, Basic) # type:ignore
def _eval_is_eq(lhs, rhs): # noqa:F811
if (lhs.rewrite(floor) == rhs) or \
(lhs.rewrite(ceiling) == rhs):
return True
# Check if other < 0
if rhs.is_extended_negative:
return False
# Check if other >= 1
res = lhs._value_one_or_more(rhs)
if res is not None:
return False
|
77859f8ac6781a244b996494caccb5079199bfc555a697f050cf70a0a9713986 | from sympy.core import sympify
from sympy.core.add import Add
from sympy.core.cache import cacheit
from sympy.core.function import (
Function, ArgumentIndexError, _coeff_isneg,
expand_mul, FunctionClass, PoleError)
from sympy.core.logic import fuzzy_and, fuzzy_not, fuzzy_or
from sympy.core.mul import Mul
from sympy.core.numbers import Integer, Rational
from sympy.core.parameters import global_parameters
from sympy.core.power import Pow
from sympy.core.singleton import S
from sympy.core.symbol import Wild, Dummy
from sympy.functions.combinatorial.factorials import factorial
from sympy.functions.elementary.miscellaneous import sqrt
from sympy.ntheory import multiplicity, perfect_power
# NOTE IMPORTANT
# The series expansion code in this file is an important part of the gruntz
# algorithm for determining limits. _eval_nseries has to return a generalized
# power series with coefficients in C(log(x), log).
# In more detail, the result of _eval_nseries(self, x, n) must be
# c_0*x**e_0 + ... (finitely many terms)
# where e_i are numbers (not necessarily integers) and c_i involve only
# numbers, the function log, and log(x). [This also means it must not contain
# log(x(1+p)), this *has* to be expanded to log(x)+log(1+p) if x.is_positive and
# p.is_positive.]
class ExpBase(Function):
unbranched = True
_singularities = (S.ComplexInfinity,)
def inverse(self, argindex=1):
"""
Returns the inverse function of ``exp(x)``.
"""
return log
def as_numer_denom(self):
"""
Returns this with a positive exponent as a 2-tuple (a fraction).
Examples
========
>>> from sympy.functions import exp
>>> from sympy.abc import x
>>> exp(-x).as_numer_denom()
(1, exp(x))
>>> exp(x).as_numer_denom()
(exp(x), 1)
"""
# this should be the same as Pow.as_numer_denom wrt
# exponent handling
exp = self.exp
neg_exp = exp.is_negative
if not neg_exp and not (-exp).is_negative:
neg_exp = _coeff_isneg(exp)
if neg_exp:
return S.One, self.func(-exp)
return self, S.One
@property
def exp(self):
"""
Returns the exponent of the function.
"""
return self.args[0]
def as_base_exp(self):
"""
Returns the 2-tuple (base, exponent).
"""
return self.func(1), Mul(*self.args)
def _eval_adjoint(self):
return self.func(self.exp.adjoint())
def _eval_conjugate(self):
return self.func(self.exp.conjugate())
def _eval_transpose(self):
return self.func(self.exp.transpose())
def _eval_is_finite(self):
arg = self.exp
if arg.is_infinite:
if arg.is_extended_negative:
return True
if arg.is_extended_positive:
return False
if arg.is_finite:
return True
def _eval_is_rational(self):
s = self.func(*self.args)
if s.func == self.func:
z = s.exp.is_zero
if z:
return True
elif s.exp.is_rational and fuzzy_not(z):
return False
else:
return s.is_rational
def _eval_is_zero(self):
return self.exp is S.NegativeInfinity
def _eval_power(self, other):
"""exp(arg)**e -> exp(arg*e) if assumptions allow it.
"""
b, e = self.as_base_exp()
return Pow._eval_power(Pow(b, e, evaluate=False), other)
def _eval_expand_power_exp(self, **hints):
from sympy import Sum, Product
arg = self.args[0]
if arg.is_Add and arg.is_commutative:
return Mul.fromiter(self.func(x) for x in arg.args)
elif isinstance(arg, Sum) and arg.is_commutative:
return Product(self.func(arg.function), *arg.limits)
return self.func(arg)
class exp_polar(ExpBase):
r"""
Represent a 'polar number' (see g-function Sphinx documentation).
Explanation
===========
``exp_polar`` represents the function
`Exp: \mathbb{C} \rightarrow \mathcal{S}`, sending the complex number
`z = a + bi` to the polar number `r = exp(a), \theta = b`. It is one of
the main functions to construct polar numbers.
Examples
========
>>> from sympy import exp_polar, pi, I, exp
The main difference is that polar numbers don't "wrap around" at `2 \pi`:
>>> exp(2*pi*I)
1
>>> exp_polar(2*pi*I)
exp_polar(2*I*pi)
apart from that they behave mostly like classical complex numbers:
>>> exp_polar(2)*exp_polar(3)
exp_polar(5)
See Also
========
sympy.simplify.powsimp.powsimp
polar_lift
periodic_argument
principal_branch
"""
is_polar = True
is_comparable = False # cannot be evalf'd
def _eval_Abs(self): # Abs is never a polar number
from sympy.functions.elementary.complexes import re
return exp(re(self.args[0]))
def _eval_evalf(self, prec):
""" Careful! any evalf of polar numbers is flaky """
from sympy import im, pi, re
i = im(self.args[0])
try:
bad = (i <= -pi or i > pi)
except TypeError:
bad = True
if bad:
return self # cannot evalf for this argument
res = exp(self.args[0])._eval_evalf(prec)
if i > 0 and im(res) < 0:
# i ~ pi, but exp(I*i) evaluated to argument slightly bigger than pi
return re(res)
return res
def _eval_power(self, other):
return self.func(self.args[0]*other)
def _eval_is_extended_real(self):
if self.args[0].is_extended_real:
return True
def as_base_exp(self):
# XXX exp_polar(0) is special!
if self.args[0] == 0:
return self, S.One
return ExpBase.as_base_exp(self)
class ExpMeta(FunctionClass):
def __instancecheck__(cls, instance):
if exp in instance.__class__.__mro__:
return True
return isinstance(instance, Pow) and instance.base is S.Exp1
class exp(ExpBase, metaclass=ExpMeta):
"""
The exponential function, :math:`e^x`.
Examples
========
>>> from sympy.functions import exp
>>> from sympy.abc import x
>>> from sympy import I, pi
>>> exp(x)
exp(x)
>>> exp(x).diff(x)
exp(x)
>>> exp(I*pi)
-1
Parameters
==========
arg : Expr
See Also
========
log
"""
def fdiff(self, argindex=1):
"""
Returns the first derivative of this function.
"""
if argindex == 1:
return self
else:
raise ArgumentIndexError(self, argindex)
def _eval_refine(self, assumptions):
from sympy.assumptions import ask, Q
arg = self.args[0]
if arg.is_Mul:
Ioo = S.ImaginaryUnit*S.Infinity
if arg in [Ioo, -Ioo]:
return S.NaN
coeff = arg.as_coefficient(S.Pi*S.ImaginaryUnit)
if coeff:
if ask(Q.integer(2*coeff)):
if ask(Q.even(coeff)):
return S.One
elif ask(Q.odd(coeff)):
return S.NegativeOne
elif ask(Q.even(coeff + S.Half)):
return -S.ImaginaryUnit
elif ask(Q.odd(coeff + S.Half)):
return S.ImaginaryUnit
@classmethod
def eval(cls, arg):
from sympy.calculus import AccumBounds
from sympy.sets.setexpr import SetExpr
from sympy.matrices.matrices import MatrixBase
from sympy import im, logcombine, re
if isinstance(arg, MatrixBase):
return arg.exp()
elif global_parameters.exp_is_pow:
return Pow(S.Exp1, arg)
elif arg.is_Number:
if arg is S.NaN:
return S.NaN
elif arg.is_zero:
return S.One
elif arg is S.One:
return S.Exp1
elif arg is S.Infinity:
return S.Infinity
elif arg is S.NegativeInfinity:
return S.Zero
elif arg is S.ComplexInfinity:
return S.NaN
elif isinstance(arg, log):
return arg.args[0]
elif isinstance(arg, AccumBounds):
return AccumBounds(exp(arg.min), exp(arg.max))
elif isinstance(arg, SetExpr):
return arg._eval_func(cls)
elif arg.is_Mul:
coeff = arg.as_coefficient(S.Pi*S.ImaginaryUnit)
if coeff:
if (2*coeff).is_integer:
if coeff.is_even:
return S.One
elif coeff.is_odd:
return S.NegativeOne
elif (coeff + S.Half).is_even:
return -S.ImaginaryUnit
elif (coeff + S.Half).is_odd:
return S.ImaginaryUnit
elif coeff.is_Rational:
ncoeff = coeff % 2 # restrict to [0, 2pi)
if ncoeff > 1: # restrict to (-pi, pi]
ncoeff -= 2
if ncoeff != coeff:
return cls(ncoeff*S.Pi*S.ImaginaryUnit)
# Warning: code in risch.py will be very sensitive to changes
# in this (see DifferentialExtension).
# look for a single log factor
coeff, terms = arg.as_coeff_Mul()
# but it can't be multiplied by oo
if coeff in [S.NegativeInfinity, S.Infinity]:
if terms.is_number:
if coeff is S.NegativeInfinity:
terms = -terms
if re(terms).is_zero and terms is not S.Zero:
return S.NaN
if re(terms).is_positive and im(terms) is not S.Zero:
return S.ComplexInfinity
if re(terms).is_negative:
return S.Zero
return None
coeffs, log_term = [coeff], None
for term in Mul.make_args(terms):
term_ = logcombine(term)
if isinstance(term_, log):
if log_term is None:
log_term = term_.args[0]
else:
return None
elif term.is_comparable:
coeffs.append(term)
else:
return None
return log_term**Mul(*coeffs) if log_term else None
elif arg.is_Add:
out = []
add = []
argchanged = False
for a in arg.args:
if a is S.One:
add.append(a)
continue
newa = cls(a)
if isinstance(newa, cls):
if newa.args[0] != a:
add.append(newa.args[0])
argchanged = True
else:
add.append(a)
else:
out.append(newa)
if out or argchanged:
return Mul(*out)*cls(Add(*add), evaluate=False)
if arg.is_zero:
return S.One
@property
def base(self):
"""
Returns the base of the exponential function.
"""
return S.Exp1
@staticmethod
@cacheit
def taylor_term(n, x, *previous_terms):
"""
Calculates the next term in the Taylor series expansion.
"""
if n < 0:
return S.Zero
if n == 0:
return S.One
x = sympify(x)
if previous_terms:
p = previous_terms[-1]
if p is not None:
return p * x / n
return x**n/factorial(n)
def as_real_imag(self, deep=True, **hints):
"""
Returns this function as a 2-tuple representing a complex number.
Examples
========
>>> from sympy import I
>>> from sympy.abc import x
>>> from sympy.functions import exp
>>> exp(x).as_real_imag()
(exp(re(x))*cos(im(x)), exp(re(x))*sin(im(x)))
>>> exp(1).as_real_imag()
(E, 0)
>>> exp(I).as_real_imag()
(cos(1), sin(1))
>>> exp(1+I).as_real_imag()
(E*cos(1), E*sin(1))
See Also
========
sympy.functions.elementary.complexes.re
sympy.functions.elementary.complexes.im
"""
from sympy.functions.elementary.trigonometric import cos, sin
re, im = self.args[0].as_real_imag()
if deep:
re = re.expand(deep, **hints)
im = im.expand(deep, **hints)
cos, sin = cos(im), sin(im)
return (exp(re)*cos, exp(re)*sin)
def _eval_subs(self, old, new):
# keep processing of power-like args centralized in Pow
if old.is_Pow: # handle (exp(3*log(x))).subs(x**2, z) -> z**(3/2)
old = exp(old.exp*log(old.base))
elif old is S.Exp1 and new.is_Function:
old = exp
if isinstance(old, exp) or old is S.Exp1:
f = lambda a: Pow(*a.as_base_exp(), evaluate=False) if (
a.is_Pow or isinstance(a, exp)) else a
return Pow._eval_subs(f(self), f(old), new)
if old is exp and not new.is_Function:
return new**self.exp._subs(old, new)
return Function._eval_subs(self, old, new)
def _eval_is_extended_real(self):
if self.args[0].is_extended_real:
return True
elif self.args[0].is_imaginary:
arg2 = -S(2) * S.ImaginaryUnit * self.args[0] / S.Pi
return arg2.is_even
def _eval_is_complex(self):
def complex_extended_negative(arg):
yield arg.is_complex
yield arg.is_extended_negative
return fuzzy_or(complex_extended_negative(self.args[0]))
def _eval_is_algebraic(self):
if (self.exp / S.Pi / S.ImaginaryUnit).is_rational:
return True
if fuzzy_not(self.exp.is_zero):
if self.exp.is_algebraic:
return False
elif (self.exp / S.Pi).is_rational:
return False
def _eval_is_extended_positive(self):
if self.exp.is_extended_real:
return not self.args[0] is S.NegativeInfinity
elif self.exp.is_imaginary:
arg2 = -S.ImaginaryUnit * self.args[0] / S.Pi
return arg2.is_even
def _eval_nseries(self, x, n, logx, cdir=0):
# NOTE Please see the comment at the beginning of this file, labelled
# IMPORTANT.
from sympy import ceiling, limit, Order, powsimp, Wild, expand_complex
arg = self.exp
arg_series = arg._eval_nseries(x, n=n, logx=logx)
if arg_series.is_Order:
return 1 + arg_series
arg0 = limit(arg_series.removeO(), x, 0)
if arg0 is S.NegativeInfinity:
return Order(x**n, x)
if arg0 is S.Infinity:
return self
t = Dummy("t")
nterms = n
try:
cf = Order(arg.as_leading_term(x, logx=logx), x).getn()
except (NotImplementedError, PoleError):
cf = 0
if cf and cf > 0:
nterms = ceiling(n/cf)
exp_series = exp(t)._taylor(t, nterms)
r = exp(arg0)*exp_series.subs(t, arg_series - arg0)
if cf and cf > 1:
r += Order((arg_series - arg0)**n, x)/x**((cf-1)*n)
else:
r += Order((arg_series - arg0)**n, x)
r = r.expand()
r = powsimp(r, deep=True, combine='exp')
# powsimp may introduce unexpanded (-1)**Rational; see PR #17201
simplerat = lambda x: x.is_Rational and x.q in [3, 4, 6]
w = Wild('w', properties=[simplerat])
r = r.replace((-1)**w, expand_complex((-1)**w))
return r
def _taylor(self, x, n):
l = []
g = None
for i in range(n):
g = self.taylor_term(i, self.args[0], g)
g = g.nseries(x, n=n)
l.append(g.removeO())
return Add(*l)
def _eval_as_leading_term(self, x, logx=None, cdir=0):
arg = self.args[0].cancel().as_leading_term(x, logx=logx)
arg0 = arg.subs(x, 0)
if arg0 is S.NaN:
arg0 = arg.limit(x, 0)
if arg0.is_infinite is False:
return exp(arg0)
raise PoleError("Cannot expand %s around 0" % (self))
def _eval_rewrite_as_sin(self, arg, **kwargs):
from sympy import sin
I = S.ImaginaryUnit
return sin(I*arg + S.Pi/2) - I*sin(I*arg)
def _eval_rewrite_as_cos(self, arg, **kwargs):
from sympy import cos
I = S.ImaginaryUnit
return cos(I*arg) + I*cos(I*arg + S.Pi/2)
def _eval_rewrite_as_tanh(self, arg, **kwargs):
from sympy import tanh
return (1 + tanh(arg/2))/(1 - tanh(arg/2))
def _eval_rewrite_as_sqrt(self, arg, **kwargs):
from sympy.functions.elementary.trigonometric import sin, cos
if arg.is_Mul:
coeff = arg.coeff(S.Pi*S.ImaginaryUnit)
if coeff and coeff.is_number:
cosine, sine = cos(S.Pi*coeff), sin(S.Pi*coeff)
if not isinstance(cosine, cos) and not isinstance (sine, sin):
return cosine + S.ImaginaryUnit*sine
def _eval_rewrite_as_Pow(self, arg, **kwargs):
if arg.is_Mul:
logs = [a for a in arg.args if isinstance(a, log) and len(a.args) == 1]
if logs:
return Pow(logs[0].args[0], arg.coeff(logs[0]))
def match_real_imag(expr):
"""
Try to match expr with a + b*I for real a and b.
``match_real_imag`` returns a tuple containing the real and imaginary
parts of expr or (None, None) if direct matching is not possible. Contrary
to ``re()``, ``im()``, ``as_real_imag()``, this helper won't force things
by returning expressions themselves containing ``re()`` or ``im()`` and it
doesn't expand its argument either.
"""
r_, i_ = expr.as_independent(S.ImaginaryUnit, as_Add=True)
if i_ == 0 and r_.is_real:
return (r_, i_)
i_ = i_.as_coefficient(S.ImaginaryUnit)
if i_ and i_.is_real and r_.is_real:
return (r_, i_)
else:
return (None, None) # simpler to check for than None
class log(Function):
r"""
The natural logarithm function `\ln(x)` or `\log(x)`.
Explanation
===========
Logarithms are taken with the natural base, `e`. To get
a logarithm of a different base ``b``, use ``log(x, b)``,
which is essentially short-hand for ``log(x)/log(b)``.
``log`` represents the principal branch of the natural
logarithm. As such it has a branch cut along the negative
real axis and returns values having a complex argument in
`(-\pi, \pi]`.
Examples
========
>>> from sympy import log, sqrt, S, I
>>> log(8, 2)
3
>>> log(S(8)/3, 2)
-log(3)/log(2) + 3
>>> log(-1 + I*sqrt(3))
log(2) + 2*I*pi/3
See Also
========
exp
"""
_singularities = (S.Zero, S.ComplexInfinity)
def fdiff(self, argindex=1):
"""
Returns the first derivative of the function.
"""
if argindex == 1:
return 1/self.args[0]
else:
raise ArgumentIndexError(self, argindex)
def inverse(self, argindex=1):
r"""
Returns `e^x`, the inverse function of `\log(x)`.
"""
return exp
@classmethod
def eval(cls, arg, base=None):
from sympy import unpolarify
from sympy.calculus import AccumBounds
from sympy.sets.setexpr import SetExpr
from sympy.functions.elementary.complexes import Abs
arg = sympify(arg)
if base is not None:
base = sympify(base)
if base == 1:
if arg == 1:
return S.NaN
else:
return S.ComplexInfinity
try:
# handle extraction of powers of the base now
# or else expand_log in Mul would have to handle this
n = multiplicity(base, arg)
if n:
return n + log(arg / base**n) / log(base)
else:
return log(arg)/log(base)
except ValueError:
pass
if base is not S.Exp1:
return cls(arg)/cls(base)
else:
return cls(arg)
if arg.is_Number:
if arg.is_zero:
return S.ComplexInfinity
elif arg is S.One:
return S.Zero
elif arg is S.Infinity:
return S.Infinity
elif arg is S.NegativeInfinity:
return S.Infinity
elif arg is S.NaN:
return S.NaN
elif arg.is_Rational and arg.p == 1:
return -cls(arg.q)
if arg.is_Pow and arg.base is S.Exp1 and arg.exp.is_extended_real:
return arg.exp
I = S.ImaginaryUnit
if isinstance(arg, exp) and arg.exp.is_extended_real:
return arg.exp
elif isinstance(arg, exp) and arg.exp.is_number:
r_, i_ = match_real_imag(arg.exp)
if i_ and i_.is_comparable:
i_ %= 2*S.Pi
if i_ > S.Pi:
i_ -= 2*S.Pi
return r_ + expand_mul(i_ * I, deep=False)
elif isinstance(arg, exp_polar):
return unpolarify(arg.exp)
elif isinstance(arg, AccumBounds):
if arg.min.is_positive:
return AccumBounds(log(arg.min), log(arg.max))
else:
return
elif isinstance(arg, SetExpr):
return arg._eval_func(cls)
if arg.is_number:
if arg.is_negative:
return S.Pi * I + cls(-arg)
elif arg is S.ComplexInfinity:
return S.ComplexInfinity
elif arg is S.Exp1:
return S.One
if arg.is_zero:
return S.ComplexInfinity
# don't autoexpand Pow or Mul (see the issue 3351):
if not arg.is_Add:
coeff = arg.as_coefficient(I)
if coeff is not None:
if coeff is S.Infinity:
return S.Infinity
elif coeff is S.NegativeInfinity:
return S.Infinity
elif coeff.is_Rational:
if coeff.is_nonnegative:
return S.Pi * I * S.Half + cls(coeff)
else:
return -S.Pi * I * S.Half + cls(-coeff)
if arg.is_number and arg.is_algebraic:
# Match arg = coeff*(r_ + i_*I) with coeff>0, r_ and i_ real.
coeff, arg_ = arg.as_independent(I, as_Add=False)
if coeff.is_negative:
coeff *= -1
arg_ *= -1
arg_ = expand_mul(arg_, deep=False)
r_, i_ = arg_.as_independent(I, as_Add=True)
i_ = i_.as_coefficient(I)
if coeff.is_real and i_ and i_.is_real and r_.is_real:
if r_.is_zero:
if i_.is_positive:
return S.Pi * I * S.Half + cls(coeff * i_)
elif i_.is_negative:
return -S.Pi * I * S.Half + cls(coeff * -i_)
else:
from sympy.simplify import ratsimp
# Check for arguments involving rational multiples of pi
t = (i_/r_).cancel()
t1 = (-t).cancel()
atan_table = {
# first quadrant only
sqrt(3): S.Pi/3,
1: S.Pi/4,
sqrt(5 - 2*sqrt(5)): S.Pi/5,
sqrt(2)*sqrt(5 - sqrt(5))/(1 + sqrt(5)): S.Pi/5,
sqrt(5 + 2*sqrt(5)): S.Pi*Rational(2, 5),
sqrt(2)*sqrt(sqrt(5) + 5)/(-1 + sqrt(5)): S.Pi*Rational(2, 5),
sqrt(3)/3: S.Pi/6,
sqrt(2) - 1: S.Pi/8,
sqrt(2 - sqrt(2))/sqrt(sqrt(2) + 2): S.Pi/8,
sqrt(2) + 1: S.Pi*Rational(3, 8),
sqrt(sqrt(2) + 2)/sqrt(2 - sqrt(2)): S.Pi*Rational(3, 8),
sqrt(1 - 2*sqrt(5)/5): S.Pi/10,
(-sqrt(2) + sqrt(10))/(2*sqrt(sqrt(5) + 5)): S.Pi/10,
sqrt(1 + 2*sqrt(5)/5): S.Pi*Rational(3, 10),
(sqrt(2) + sqrt(10))/(2*sqrt(5 - sqrt(5))): S.Pi*Rational(3, 10),
2 - sqrt(3): S.Pi/12,
(-1 + sqrt(3))/(1 + sqrt(3)): S.Pi/12,
2 + sqrt(3): S.Pi*Rational(5, 12),
(1 + sqrt(3))/(-1 + sqrt(3)): S.Pi*Rational(5, 12)
}
if t in atan_table:
modulus = ratsimp(coeff * Abs(arg_))
if r_.is_positive:
return cls(modulus) + I * atan_table[t]
else:
return cls(modulus) + I * (atan_table[t] - S.Pi)
elif t1 in atan_table:
modulus = ratsimp(coeff * Abs(arg_))
if r_.is_positive:
return cls(modulus) + I * (-atan_table[t1])
else:
return cls(modulus) + I * (S.Pi - atan_table[t1])
def as_base_exp(self):
"""
Returns this function in the form (base, exponent).
"""
return self, S.One
@staticmethod
@cacheit
def taylor_term(n, x, *previous_terms): # of log(1+x)
r"""
Returns the next term in the Taylor series expansion of `\log(1+x)`.
"""
from sympy import powsimp
if n < 0:
return S.Zero
x = sympify(x)
if n == 0:
return x
if previous_terms:
p = previous_terms[-1]
if p is not None:
return powsimp((-n) * p * x / (n + 1), deep=True, combine='exp')
return (1 - 2*(n % 2)) * x**(n + 1)/(n + 1)
def _eval_expand_log(self, deep=True, **hints):
from sympy import unpolarify, expand_log, factorint
from sympy.concrete import Sum, Product
force = hints.get('force', False)
factor = hints.get('factor', False)
if (len(self.args) == 2):
return expand_log(self.func(*self.args), deep=deep, force=force)
arg = self.args[0]
if arg.is_Integer:
# remove perfect powers
p = perfect_power(arg)
logarg = None
coeff = 1
if p is not False:
arg, coeff = p
logarg = self.func(arg)
# expand as product of its prime factors if factor=True
if factor:
p = factorint(arg)
if arg not in p.keys():
logarg = sum(n*log(val) for val, n in p.items())
if logarg is not None:
return coeff*logarg
elif arg.is_Rational:
return log(arg.p) - log(arg.q)
elif arg.is_Mul:
expr = []
nonpos = []
for x in arg.args:
if force or x.is_positive or x.is_polar:
a = self.func(x)
if isinstance(a, log):
expr.append(self.func(x)._eval_expand_log(**hints))
else:
expr.append(a)
elif x.is_negative:
a = self.func(-x)
expr.append(a)
nonpos.append(S.NegativeOne)
else:
nonpos.append(x)
return Add(*expr) + log(Mul(*nonpos))
elif arg.is_Pow or isinstance(arg, exp):
if force or (arg.exp.is_extended_real and (arg.base.is_positive or ((arg.exp+1)
.is_positive and (arg.exp-1).is_nonpositive))) or arg.base.is_polar:
b = arg.base
e = arg.exp
a = self.func(b)
if isinstance(a, log):
return unpolarify(e) * a._eval_expand_log(**hints)
else:
return unpolarify(e) * a
elif isinstance(arg, Product):
if force or arg.function.is_positive:
return Sum(log(arg.function), *arg.limits)
return self.func(arg)
def _eval_simplify(self, **kwargs):
from sympy.simplify.simplify import expand_log, simplify, inversecombine
if len(self.args) == 2: # it's unevaluated
return simplify(self.func(*self.args), **kwargs)
expr = self.func(simplify(self.args[0], **kwargs))
if kwargs['inverse']:
expr = inversecombine(expr)
expr = expand_log(expr, deep=True)
return min([expr, self], key=kwargs['measure'])
def as_real_imag(self, deep=True, **hints):
"""
Returns this function as a complex coordinate.
Examples
========
>>> from sympy import I
>>> from sympy.abc import x
>>> from sympy.functions import log
>>> log(x).as_real_imag()
(log(Abs(x)), arg(x))
>>> log(I).as_real_imag()
(0, pi/2)
>>> log(1 + I).as_real_imag()
(log(sqrt(2)), pi/4)
>>> log(I*x).as_real_imag()
(log(Abs(x)), arg(I*x))
"""
from sympy import Abs, arg
sarg = self.args[0]
if deep:
sarg = self.args[0].expand(deep, **hints)
abs = Abs(sarg)
if abs == sarg:
return self, S.Zero
arg = arg(sarg)
if hints.get('log', False): # Expand the log
hints['complex'] = False
return (log(abs).expand(deep, **hints), arg)
else:
return log(abs), arg
def _eval_is_rational(self):
s = self.func(*self.args)
if s.func == self.func:
if (self.args[0] - 1).is_zero:
return True
if s.args[0].is_rational and fuzzy_not((self.args[0] - 1).is_zero):
return False
else:
return s.is_rational
def _eval_is_algebraic(self):
s = self.func(*self.args)
if s.func == self.func:
if (self.args[0] - 1).is_zero:
return True
elif fuzzy_not((self.args[0] - 1).is_zero):
if self.args[0].is_algebraic:
return False
else:
return s.is_algebraic
def _eval_is_extended_real(self):
return self.args[0].is_extended_positive
def _eval_is_complex(self):
z = self.args[0]
return fuzzy_and([z.is_complex, fuzzy_not(z.is_zero)])
def _eval_is_finite(self):
arg = self.args[0]
if arg.is_zero:
return False
return arg.is_finite
def _eval_is_extended_positive(self):
return (self.args[0] - 1).is_extended_positive
def _eval_is_zero(self):
return (self.args[0] - 1).is_zero
def _eval_is_extended_nonnegative(self):
return (self.args[0] - 1).is_extended_nonnegative
def _eval_nseries(self, x, n, logx, cdir=0):
# NOTE Please see the comment at the beginning of this file, labelled
# IMPORTANT.
from sympy import im, cancel, I, Order, logcombine
from itertools import product
if not logx:
logx = log(x)
if self.args[0] == x:
return logx
arg = self.args[0]
k, l = Wild("k"), Wild("l")
r = arg.match(k*x**l)
if r is not None:
k, l = r[k], r[l]
if l != 0 and not l.has(x) and not k.has(x):
r = log(k) + l*logx # XXX true regardless of assumptions?
return r
def coeff_exp(term, x):
coeff, exp = S.One, S.Zero
for factor in Mul.make_args(term):
if factor.has(x):
base, exp = factor.as_base_exp()
if base != x:
try:
return term.leadterm(x)
except ValueError:
return term, S.Zero
else:
coeff *= factor
return coeff, exp
# TODO new and probably slow
try:
a, b = arg.leadterm(x)
s = arg.nseries(x, n=n+b, logx=logx)
except (ValueError, NotImplementedError, PoleError):
s = arg.nseries(x, n=n, logx=logx)
while s.is_Order:
n += 1
s = arg.nseries(x, n=n, logx=logx)
a, b = s.removeO().leadterm(x)
p = cancel(s/(a*x**b) - 1).expand().powsimp()
if p.has(exp):
p = logcombine(p)
if isinstance(p, Order):
n = p.getn()
_, d = coeff_exp(p, x)
if not d.is_positive:
return log(a) + b*logx + Order(x**n, x)
def mul(d1, d2):
res = {}
for e1, e2 in product(d1, d2):
ex = e1 + e2
if ex < n:
res[ex] = res.get(ex, S.Zero) + d1[e1]*d2[e2]
return res
pterms = {}
for term in Add.make_args(p):
co1, e1 = coeff_exp(term, x)
pterms[e1] = pterms.get(e1, S.Zero) + co1.removeO()
k = S.One
terms = {}
pk = pterms
while k*d < n:
coeff = -(-1)**k/k
for ex in pk:
terms[ex] = terms.get(ex, S.Zero) + coeff*pk[ex]
pk = mul(pk, pterms)
k += S.One
res = log(a) + b*logx
for ex in terms:
res += terms[ex]*x**(ex)
if cdir != 0:
cdir = self.args[0].dir(x, cdir)
if a.is_real and a.is_negative and im(cdir) < 0:
res -= 2*I*S.Pi
return res + Order(x**n, x)
def _eval_as_leading_term(self, x, logx=None, cdir=0):
from sympy import I, im, re
arg0 = self.args[0].together()
arg = arg0.as_leading_term(x, cdir=cdir)
x0 = arg0.subs(x, 0)
if (x0 is S.NaN and logx is None):
x0 = arg.limit(x, 0, dir='-' if re(cdir).is_negative else '+')
if x0 in (S.NegativeInfinity, S.Infinity):
raise PoleError("Cannot expand %s around 0" % (self))
if x0 == 1:
return (arg0 - S.One).as_leading_term(x)
if cdir != 0:
cdir = arg0.dir(x, cdir)
if x0.is_real and x0.is_negative and im(cdir).is_negative:
return self.func(x0) - 2*I*S.Pi
return self.func(arg)
class LambertW(Function):
r"""
The Lambert W function `W(z)` is defined as the inverse
function of `w \exp(w)` [1]_.
Explanation
===========
In other words, the value of `W(z)` is such that `z = W(z) \exp(W(z))`
for any complex number `z`. The Lambert W function is a multivalued
function with infinitely many branches `W_k(z)`, indexed by
`k \in \mathbb{Z}`. Each branch gives a different solution `w`
of the equation `z = w \exp(w)`.
The Lambert W function has two partially real branches: the
principal branch (`k = 0`) is real for real `z > -1/e`, and the
`k = -1` branch is real for `-1/e < z < 0`. All branches except
`k = 0` have a logarithmic singularity at `z = 0`.
Examples
========
>>> from sympy import LambertW
>>> LambertW(1.2)
0.635564016364870
>>> LambertW(1.2, -1).n()
-1.34747534407696 - 4.41624341514535*I
>>> LambertW(-1).is_real
False
References
==========
.. [1] https://en.wikipedia.org/wiki/Lambert_W_function
"""
_singularities = (-Pow(S.Exp1, -1, evaluate=False), S.ComplexInfinity)
@classmethod
def eval(cls, x, k=None):
if k == S.Zero:
return cls(x)
elif k is None:
k = S.Zero
if k.is_zero:
if x.is_zero:
return S.Zero
if x is S.Exp1:
return S.One
if x == -1/S.Exp1:
return S.NegativeOne
if x == -log(2)/2:
return -log(2)
if x == 2*log(2):
return log(2)
if x == -S.Pi/2:
return S.ImaginaryUnit*S.Pi/2
if x == exp(1 + S.Exp1):
return S.Exp1
if x is S.Infinity:
return S.Infinity
if x.is_zero:
return S.Zero
if fuzzy_not(k.is_zero):
if x.is_zero:
return S.NegativeInfinity
if k is S.NegativeOne:
if x == -S.Pi/2:
return -S.ImaginaryUnit*S.Pi/2
elif x == -1/S.Exp1:
return S.NegativeOne
elif x == -2*exp(-2):
return -Integer(2)
def fdiff(self, argindex=1):
"""
Return the first derivative of this function.
"""
x = self.args[0]
if len(self.args) == 1:
if argindex == 1:
return LambertW(x)/(x*(1 + LambertW(x)))
else:
k = self.args[1]
if argindex == 1:
return LambertW(x, k)/(x*(1 + LambertW(x, k)))
raise ArgumentIndexError(self, argindex)
def _eval_is_extended_real(self):
x = self.args[0]
if len(self.args) == 1:
k = S.Zero
else:
k = self.args[1]
if k.is_zero:
if (x + 1/S.Exp1).is_positive:
return True
elif (x + 1/S.Exp1).is_nonpositive:
return False
elif (k + 1).is_zero:
if x.is_negative and (x + 1/S.Exp1).is_positive:
return True
elif x.is_nonpositive or (x + 1/S.Exp1).is_nonnegative:
return False
elif fuzzy_not(k.is_zero) and fuzzy_not((k + 1).is_zero):
if x.is_extended_real:
return False
def _eval_is_finite(self):
return self.args[0].is_finite
def _eval_is_algebraic(self):
s = self.func(*self.args)
if s.func == self.func:
if fuzzy_not(self.args[0].is_zero) and self.args[0].is_algebraic:
return False
else:
return s.is_algebraic
def _eval_as_leading_term(self, x, logx=None, cdir=0):
if len(self.args) == 1:
arg = self.args[0]
arg0 = arg.subs(x, 0).cancel()
if not arg0.is_zero:
return self.func(arg0)
return arg.as_leading_term(x)
def _eval_nseries(self, x, n, logx, cdir=0):
if len(self.args) == 1:
from sympy import Order, ceiling, expand_multinomial
arg = self.args[0].nseries(x, n=n, logx=logx)
lt = arg.compute_leading_term(x, logx=logx)
lte = 1
if lt.is_Pow:
lte = lt.exp
if ceiling(n/lte) >= 1:
s = Add(*[(-S.One)**(k - 1)*Integer(k)**(k - 2)/
factorial(k - 1)*arg**k for k in range(1, ceiling(n/lte))])
s = expand_multinomial(s)
else:
s = S.Zero
return s + Order(x**n, x)
return super()._eval_nseries(x, n, logx)
def _eval_is_zero(self):
x = self.args[0]
if len(self.args) == 1:
k = S.Zero
else:
k = self.args[1]
if x.is_zero and k.is_zero:
return True
|
ab42b70c32db6fcb790b2f9c990aa303b62965311cc6d321235bcbdfddf40595 | from sympy.core.logic import FuzzyBool
from sympy.core import S, sympify, cacheit, pi, I, Rational
from sympy.core.add import Add
from sympy.core.function import Function, ArgumentIndexError, _coeff_isneg
from sympy.functions.combinatorial.factorials import factorial, RisingFactorial
from sympy.functions.elementary.exponential import exp, log, match_real_imag
from sympy.functions.elementary.miscellaneous import sqrt
from sympy.functions.elementary.integers import floor
from sympy.core.logic import fuzzy_or, fuzzy_and
def _rewrite_hyperbolics_as_exp(expr):
expr = sympify(expr)
return expr.xreplace({h: h.rewrite(exp)
for h in expr.atoms(HyperbolicFunction)})
###############################################################################
########################### HYPERBOLIC FUNCTIONS ##############################
###############################################################################
class HyperbolicFunction(Function):
"""
Base class for hyperbolic functions.
See Also
========
sinh, cosh, tanh, coth
"""
unbranched = True
def _peeloff_ipi(arg):
"""
Split ARG into two parts, a "rest" and a multiple of I*pi/2.
This assumes ARG to be an Add.
The multiple of I*pi returned in the second position is always a Rational.
Examples
========
>>> from sympy.functions.elementary.hyperbolic import _peeloff_ipi as peel
>>> from sympy import pi, I
>>> from sympy.abc import x, y
>>> peel(x + I*pi/2)
(x, I*pi/2)
>>> peel(x + I*2*pi/3 + I*pi*y)
(x + I*pi*y + I*pi/6, I*pi/2)
"""
for a in Add.make_args(arg):
if a == S.Pi*S.ImaginaryUnit:
K = S.One
break
elif a.is_Mul:
K, p = a.as_two_terms()
if p == S.Pi*S.ImaginaryUnit and K.is_Rational:
break
else:
return arg, S.Zero
m1 = (K % S.Half)*S.Pi*S.ImaginaryUnit
m2 = K*S.Pi*S.ImaginaryUnit - m1
return arg - m2, m2
class sinh(HyperbolicFunction):
r"""
sinh(x) is the hyperbolic sine of x.
The hyperbolic sine function is $\frac{e^x - e^{-x}}{2}$.
Examples
========
>>> from sympy import sinh
>>> from sympy.abc import x
>>> sinh(x)
sinh(x)
See Also
========
cosh, tanh, asinh
"""
def fdiff(self, argindex=1):
"""
Returns the first derivative of this function.
"""
if argindex == 1:
return cosh(self.args[0])
else:
raise ArgumentIndexError(self, argindex)
def inverse(self, argindex=1):
"""
Returns the inverse of this function.
"""
return asinh
@classmethod
def eval(cls, arg):
from sympy import sin
arg = sympify(arg)
if arg.is_Number:
if arg is S.NaN:
return S.NaN
elif arg is S.Infinity:
return S.Infinity
elif arg is S.NegativeInfinity:
return S.NegativeInfinity
elif arg.is_zero:
return S.Zero
elif arg.is_negative:
return -cls(-arg)
else:
if arg is S.ComplexInfinity:
return S.NaN
i_coeff = arg.as_coefficient(S.ImaginaryUnit)
if i_coeff is not None:
return S.ImaginaryUnit * sin(i_coeff)
else:
if _coeff_isneg(arg):
return -cls(-arg)
if arg.is_Add:
x, m = _peeloff_ipi(arg)
if m:
return sinh(m)*cosh(x) + cosh(m)*sinh(x)
if arg.is_zero:
return S.Zero
if arg.func == asinh:
return arg.args[0]
if arg.func == acosh:
x = arg.args[0]
return sqrt(x - 1) * sqrt(x + 1)
if arg.func == atanh:
x = arg.args[0]
return x/sqrt(1 - x**2)
if arg.func == acoth:
x = arg.args[0]
return 1/(sqrt(x - 1) * sqrt(x + 1))
@staticmethod
@cacheit
def taylor_term(n, x, *previous_terms):
"""
Returns the next term in the Taylor series expansion.
"""
if n < 0 or n % 2 == 0:
return S.Zero
else:
x = sympify(x)
if len(previous_terms) > 2:
p = previous_terms[-2]
return p * x**2 / (n*(n - 1))
else:
return x**(n) / factorial(n)
def _eval_conjugate(self):
return self.func(self.args[0].conjugate())
def as_real_imag(self, deep=True, **hints):
"""
Returns this function as a complex coordinate.
"""
from sympy import cos, sin
if self.args[0].is_extended_real:
if deep:
hints['complex'] = False
return (self.expand(deep, **hints), S.Zero)
else:
return (self, S.Zero)
if deep:
re, im = self.args[0].expand(deep, **hints).as_real_imag()
else:
re, im = self.args[0].as_real_imag()
return (sinh(re)*cos(im), cosh(re)*sin(im))
def _eval_expand_complex(self, deep=True, **hints):
re_part, im_part = self.as_real_imag(deep=deep, **hints)
return re_part + im_part*S.ImaginaryUnit
def _eval_expand_trig(self, deep=True, **hints):
if deep:
arg = self.args[0].expand(deep, **hints)
else:
arg = self.args[0]
x = None
if arg.is_Add: # TODO, implement more if deep stuff here
x, y = arg.as_two_terms()
else:
coeff, terms = arg.as_coeff_Mul(rational=True)
if coeff is not S.One and coeff.is_Integer and terms is not S.One:
x = terms
y = (coeff - 1)*x
if x is not None:
return (sinh(x)*cosh(y) + sinh(y)*cosh(x)).expand(trig=True)
return sinh(arg)
def _eval_rewrite_as_tractable(self, arg, limitvar=None, **kwargs):
return (exp(arg) - exp(-arg)) / 2
def _eval_rewrite_as_exp(self, arg, **kwargs):
return (exp(arg) - exp(-arg)) / 2
def _eval_rewrite_as_cosh(self, arg, **kwargs):
return -S.ImaginaryUnit*cosh(arg + S.Pi*S.ImaginaryUnit/2)
def _eval_rewrite_as_tanh(self, arg, **kwargs):
tanh_half = tanh(S.Half*arg)
return 2*tanh_half/(1 - tanh_half**2)
def _eval_rewrite_as_coth(self, arg, **kwargs):
coth_half = coth(S.Half*arg)
return 2*coth_half/(coth_half**2 - 1)
def _eval_as_leading_term(self, x, logx=None, cdir=0):
arg = self.args[0].as_leading_term(x, logx=logx, cdir=cdir)
arg0 = arg.subs(x, 0)
if arg0 is S.NaN:
arg0 = arg.limit(x, 0, dir='-' if cdir.is_negative else '+')
if arg0.is_zero:
return arg
elif arg0.is_finite:
return self.func(arg0)
else:
return self
def _eval_is_real(self):
arg = self.args[0]
if arg.is_real:
return True
# if `im` is of the form n*pi
# else, check if it is a number
re, im = arg.as_real_imag()
return (im%pi).is_zero
def _eval_is_extended_real(self):
if self.args[0].is_extended_real:
return True
def _eval_is_positive(self):
if self.args[0].is_extended_real:
return self.args[0].is_positive
def _eval_is_negative(self):
if self.args[0].is_extended_real:
return self.args[0].is_negative
def _eval_is_finite(self):
arg = self.args[0]
return arg.is_finite
def _eval_is_zero(self):
arg = self.args[0]
if arg.is_zero:
return True
class cosh(HyperbolicFunction):
r"""
cosh(x) is the hyperbolic cosine of x.
The hyperbolic cosine function is $\frac{e^x + e^{-x}}{2}$.
Examples
========
>>> from sympy import cosh
>>> from sympy.abc import x
>>> cosh(x)
cosh(x)
See Also
========
sinh, tanh, acosh
"""
def fdiff(self, argindex=1):
if argindex == 1:
return sinh(self.args[0])
else:
raise ArgumentIndexError(self, argindex)
@classmethod
def eval(cls, arg):
from sympy import cos
arg = sympify(arg)
if arg.is_Number:
if arg is S.NaN:
return S.NaN
elif arg is S.Infinity:
return S.Infinity
elif arg is S.NegativeInfinity:
return S.Infinity
elif arg.is_zero:
return S.One
elif arg.is_negative:
return cls(-arg)
else:
if arg is S.ComplexInfinity:
return S.NaN
i_coeff = arg.as_coefficient(S.ImaginaryUnit)
if i_coeff is not None:
return cos(i_coeff)
else:
if _coeff_isneg(arg):
return cls(-arg)
if arg.is_Add:
x, m = _peeloff_ipi(arg)
if m:
return cosh(m)*cosh(x) + sinh(m)*sinh(x)
if arg.is_zero:
return S.One
if arg.func == asinh:
return sqrt(1 + arg.args[0]**2)
if arg.func == acosh:
return arg.args[0]
if arg.func == atanh:
return 1/sqrt(1 - arg.args[0]**2)
if arg.func == acoth:
x = arg.args[0]
return x/(sqrt(x - 1) * sqrt(x + 1))
@staticmethod
@cacheit
def taylor_term(n, x, *previous_terms):
if n < 0 or n % 2 == 1:
return S.Zero
else:
x = sympify(x)
if len(previous_terms) > 2:
p = previous_terms[-2]
return p * x**2 / (n*(n - 1))
else:
return x**(n)/factorial(n)
def _eval_conjugate(self):
return self.func(self.args[0].conjugate())
def as_real_imag(self, deep=True, **hints):
from sympy import cos, sin
if self.args[0].is_extended_real:
if deep:
hints['complex'] = False
return (self.expand(deep, **hints), S.Zero)
else:
return (self, S.Zero)
if deep:
re, im = self.args[0].expand(deep, **hints).as_real_imag()
else:
re, im = self.args[0].as_real_imag()
return (cosh(re)*cos(im), sinh(re)*sin(im))
def _eval_expand_complex(self, deep=True, **hints):
re_part, im_part = self.as_real_imag(deep=deep, **hints)
return re_part + im_part*S.ImaginaryUnit
def _eval_expand_trig(self, deep=True, **hints):
if deep:
arg = self.args[0].expand(deep, **hints)
else:
arg = self.args[0]
x = None
if arg.is_Add: # TODO, implement more if deep stuff here
x, y = arg.as_two_terms()
else:
coeff, terms = arg.as_coeff_Mul(rational=True)
if coeff is not S.One and coeff.is_Integer and terms is not S.One:
x = terms
y = (coeff - 1)*x
if x is not None:
return (cosh(x)*cosh(y) + sinh(x)*sinh(y)).expand(trig=True)
return cosh(arg)
def _eval_rewrite_as_tractable(self, arg, limitvar=None, **kwargs):
return (exp(arg) + exp(-arg)) / 2
def _eval_rewrite_as_exp(self, arg, **kwargs):
return (exp(arg) + exp(-arg)) / 2
def _eval_rewrite_as_sinh(self, arg, **kwargs):
return -S.ImaginaryUnit*sinh(arg + S.Pi*S.ImaginaryUnit/2)
def _eval_rewrite_as_tanh(self, arg, **kwargs):
tanh_half = tanh(S.Half*arg)**2
return (1 + tanh_half)/(1 - tanh_half)
def _eval_rewrite_as_coth(self, arg, **kwargs):
coth_half = coth(S.Half*arg)**2
return (coth_half + 1)/(coth_half - 1)
def _eval_as_leading_term(self, x, logx=None, cdir=0):
arg = self.args[0].as_leading_term(x, logx=logx, cdir=cdir)
arg0 = arg.subs(x, 0)
if arg0 is S.NaN:
arg0 = arg.limit(x, 0, dir='-' if cdir.is_negative else '+')
if arg0.is_zero:
return S.One
elif arg0.is_finite:
return self.func(arg0)
else:
return self
def _eval_is_real(self):
arg = self.args[0]
# `cosh(x)` is real for real OR purely imaginary `x`
if arg.is_real or arg.is_imaginary:
return True
# cosh(a+ib) = cos(b)*cosh(a) + i*sin(b)*sinh(a)
# the imaginary part can be an expression like n*pi
# if not, check if the imaginary part is a number
re, im = arg.as_real_imag()
return (im%pi).is_zero
def _eval_is_positive(self):
# cosh(x+I*y) = cos(y)*cosh(x) + I*sin(y)*sinh(x)
# cosh(z) is positive iff it is real and the real part is positive.
# So we need sin(y)*sinh(x) = 0 which gives x=0 or y=n*pi
# Case 1 (y=n*pi): cosh(z) = (-1)**n * cosh(x) -> positive for n even
# Case 2 (x=0): cosh(z) = cos(y) -> positive when cos(y) is positive
z = self.args[0]
x, y = z.as_real_imag()
ymod = y % (2*pi)
yzero = ymod.is_zero
# shortcut if ymod is zero
if yzero:
return True
xzero = x.is_zero
# shortcut x is not zero
if xzero is False:
return yzero
return fuzzy_or([
# Case 1:
yzero,
# Case 2:
fuzzy_and([
xzero,
fuzzy_or([ymod < pi/2, ymod > 3*pi/2])
])
])
def _eval_is_nonnegative(self):
z = self.args[0]
x, y = z.as_real_imag()
ymod = y % (2*pi)
yzero = ymod.is_zero
# shortcut if ymod is zero
if yzero:
return True
xzero = x.is_zero
# shortcut x is not zero
if xzero is False:
return yzero
return fuzzy_or([
# Case 1:
yzero,
# Case 2:
fuzzy_and([
xzero,
fuzzy_or([ymod <= pi/2, ymod >= 3*pi/2])
])
])
def _eval_is_finite(self):
arg = self.args[0]
return arg.is_finite
class tanh(HyperbolicFunction):
r"""
tanh(x) is the hyperbolic tangent of x.
The hyperbolic tangent function is $\frac{\sinh(x)}{\cosh(x)}$.
Examples
========
>>> from sympy import tanh
>>> from sympy.abc import x
>>> tanh(x)
tanh(x)
See Also
========
sinh, cosh, atanh
"""
def fdiff(self, argindex=1):
if argindex == 1:
return S.One - tanh(self.args[0])**2
else:
raise ArgumentIndexError(self, argindex)
def inverse(self, argindex=1):
"""
Returns the inverse of this function.
"""
return atanh
@classmethod
def eval(cls, arg):
from sympy import tan
arg = sympify(arg)
if arg.is_Number:
if arg is S.NaN:
return S.NaN
elif arg is S.Infinity:
return S.One
elif arg is S.NegativeInfinity:
return S.NegativeOne
elif arg.is_zero:
return S.Zero
elif arg.is_negative:
return -cls(-arg)
else:
if arg is S.ComplexInfinity:
return S.NaN
i_coeff = arg.as_coefficient(S.ImaginaryUnit)
if i_coeff is not None:
if _coeff_isneg(i_coeff):
return -S.ImaginaryUnit * tan(-i_coeff)
return S.ImaginaryUnit * tan(i_coeff)
else:
if _coeff_isneg(arg):
return -cls(-arg)
if arg.is_Add:
x, m = _peeloff_ipi(arg)
if m:
tanhm = tanh(m)
if tanhm is S.ComplexInfinity:
return coth(x)
else: # tanhm == 0
return tanh(x)
if arg.is_zero:
return S.Zero
if arg.func == asinh:
x = arg.args[0]
return x/sqrt(1 + x**2)
if arg.func == acosh:
x = arg.args[0]
return sqrt(x - 1) * sqrt(x + 1) / x
if arg.func == atanh:
return arg.args[0]
if arg.func == acoth:
return 1/arg.args[0]
@staticmethod
@cacheit
def taylor_term(n, x, *previous_terms):
from sympy import bernoulli
if n < 0 or n % 2 == 0:
return S.Zero
else:
x = sympify(x)
a = 2**(n + 1)
B = bernoulli(n + 1)
F = factorial(n + 1)
return a*(a - 1) * B/F * x**n
def _eval_conjugate(self):
return self.func(self.args[0].conjugate())
def as_real_imag(self, deep=True, **hints):
from sympy import cos, sin
if self.args[0].is_extended_real:
if deep:
hints['complex'] = False
return (self.expand(deep, **hints), S.Zero)
else:
return (self, S.Zero)
if deep:
re, im = self.args[0].expand(deep, **hints).as_real_imag()
else:
re, im = self.args[0].as_real_imag()
denom = sinh(re)**2 + cos(im)**2
return (sinh(re)*cosh(re)/denom, sin(im)*cos(im)/denom)
def _eval_expand_trig(self, **hints):
arg = self.args[0]
if arg.is_Add:
from sympy import symmetric_poly
n = len(arg.args)
TX = [tanh(x, evaluate=False)._eval_expand_trig()
for x in arg.args]
p = [0, 0] # [den, num]
for i in range(n + 1):
p[i % 2] += symmetric_poly(i, TX)
return p[1]/p[0]
elif arg.is_Mul:
from sympy.functions.combinatorial.numbers import nC
coeff, terms = arg.as_coeff_Mul()
if coeff.is_Integer and coeff > 1:
n = []
d = []
T = tanh(terms)
for k in range(1, coeff + 1, 2):
n.append(nC(range(coeff), k)*T**k)
for k in range(0, coeff + 1, 2):
d.append(nC(range(coeff), k)*T**k)
return Add(*n)/Add(*d)
return tanh(arg)
def _eval_rewrite_as_tractable(self, arg, limitvar=None, **kwargs):
neg_exp, pos_exp = exp(-arg), exp(arg)
return (pos_exp - neg_exp)/(pos_exp + neg_exp)
def _eval_rewrite_as_exp(self, arg, **kwargs):
neg_exp, pos_exp = exp(-arg), exp(arg)
return (pos_exp - neg_exp)/(pos_exp + neg_exp)
def _eval_rewrite_as_sinh(self, arg, **kwargs):
return S.ImaginaryUnit*sinh(arg)/sinh(S.Pi*S.ImaginaryUnit/2 - arg)
def _eval_rewrite_as_cosh(self, arg, **kwargs):
return S.ImaginaryUnit*cosh(S.Pi*S.ImaginaryUnit/2 - arg)/cosh(arg)
def _eval_rewrite_as_coth(self, arg, **kwargs):
return 1/coth(arg)
def _eval_as_leading_term(self, x, logx=None, cdir=0):
from sympy import Order
arg = self.args[0].as_leading_term(x)
if x in arg.free_symbols and Order(1, x).contains(arg):
return arg
else:
return self.func(arg)
def _eval_is_real(self):
arg = self.args[0]
if arg.is_real:
return True
re, im = arg.as_real_imag()
# if denom = 0, tanh(arg) = zoo
if re == 0 and im % pi == pi/2:
return None
# check if im is of the form n*pi/2 to make sin(2*im) = 0
# if not, im could be a number, return False in that case
return (im % (pi/2)).is_zero
def _eval_is_extended_real(self):
if self.args[0].is_extended_real:
return True
def _eval_is_positive(self):
if self.args[0].is_extended_real:
return self.args[0].is_positive
def _eval_is_negative(self):
if self.args[0].is_extended_real:
return self.args[0].is_negative
def _eval_is_finite(self):
from sympy import sinh, cos
arg = self.args[0]
re, im = arg.as_real_imag()
denom = cos(im)**2 + sinh(re)**2
if denom == 0:
return False
elif denom.is_number:
return True
if arg.is_extended_real:
return True
def _eval_is_zero(self):
arg = self.args[0]
if arg.is_zero:
return True
class coth(HyperbolicFunction):
r"""
coth(x) is the hyperbolic cotangent of x.
The hyperbolic cotangent function is $\frac{\cosh(x)}{\sinh(x)}$.
Examples
========
>>> from sympy import coth
>>> from sympy.abc import x
>>> coth(x)
coth(x)
See Also
========
sinh, cosh, acoth
"""
def fdiff(self, argindex=1):
if argindex == 1:
return -1/sinh(self.args[0])**2
else:
raise ArgumentIndexError(self, argindex)
def inverse(self, argindex=1):
"""
Returns the inverse of this function.
"""
return acoth
@classmethod
def eval(cls, arg):
from sympy import cot
arg = sympify(arg)
if arg.is_Number:
if arg is S.NaN:
return S.NaN
elif arg is S.Infinity:
return S.One
elif arg is S.NegativeInfinity:
return S.NegativeOne
elif arg.is_zero:
return S.ComplexInfinity
elif arg.is_negative:
return -cls(-arg)
else:
if arg is S.ComplexInfinity:
return S.NaN
i_coeff = arg.as_coefficient(S.ImaginaryUnit)
if i_coeff is not None:
if _coeff_isneg(i_coeff):
return S.ImaginaryUnit * cot(-i_coeff)
return -S.ImaginaryUnit * cot(i_coeff)
else:
if _coeff_isneg(arg):
return -cls(-arg)
if arg.is_Add:
x, m = _peeloff_ipi(arg)
if m:
cothm = coth(m)
if cothm is S.ComplexInfinity:
return coth(x)
else: # cothm == 0
return tanh(x)
if arg.is_zero:
return S.ComplexInfinity
if arg.func == asinh:
x = arg.args[0]
return sqrt(1 + x**2)/x
if arg.func == acosh:
x = arg.args[0]
return x/(sqrt(x - 1) * sqrt(x + 1))
if arg.func == atanh:
return 1/arg.args[0]
if arg.func == acoth:
return arg.args[0]
@staticmethod
@cacheit
def taylor_term(n, x, *previous_terms):
from sympy import bernoulli
if n == 0:
return 1 / sympify(x)
elif n < 0 or n % 2 == 0:
return S.Zero
else:
x = sympify(x)
B = bernoulli(n + 1)
F = factorial(n + 1)
return 2**(n + 1) * B/F * x**n
def _eval_conjugate(self):
return self.func(self.args[0].conjugate())
def as_real_imag(self, deep=True, **hints):
from sympy import cos, sin
if self.args[0].is_extended_real:
if deep:
hints['complex'] = False
return (self.expand(deep, **hints), S.Zero)
else:
return (self, S.Zero)
if deep:
re, im = self.args[0].expand(deep, **hints).as_real_imag()
else:
re, im = self.args[0].as_real_imag()
denom = sinh(re)**2 + sin(im)**2
return (sinh(re)*cosh(re)/denom, -sin(im)*cos(im)/denom)
def _eval_rewrite_as_tractable(self, arg, limitvar=None, **kwargs):
neg_exp, pos_exp = exp(-arg), exp(arg)
return (pos_exp + neg_exp)/(pos_exp - neg_exp)
def _eval_rewrite_as_exp(self, arg, **kwargs):
neg_exp, pos_exp = exp(-arg), exp(arg)
return (pos_exp + neg_exp)/(pos_exp - neg_exp)
def _eval_rewrite_as_sinh(self, arg, **kwargs):
return -S.ImaginaryUnit*sinh(S.Pi*S.ImaginaryUnit/2 - arg)/sinh(arg)
def _eval_rewrite_as_cosh(self, arg, **kwargs):
return -S.ImaginaryUnit*cosh(arg)/cosh(S.Pi*S.ImaginaryUnit/2 - arg)
def _eval_rewrite_as_tanh(self, arg, **kwargs):
return 1/tanh(arg)
def _eval_is_positive(self):
if self.args[0].is_extended_real:
return self.args[0].is_positive
def _eval_is_negative(self):
if self.args[0].is_extended_real:
return self.args[0].is_negative
def _eval_as_leading_term(self, x, logx=None, cdir=0):
from sympy import Order
arg = self.args[0].as_leading_term(x)
if x in arg.free_symbols and Order(1, x).contains(arg):
return 1/arg
else:
return self.func(arg)
def _eval_expand_trig(self, **hints):
arg = self.args[0]
if arg.is_Add:
from sympy import symmetric_poly
CX = [coth(x, evaluate=False)._eval_expand_trig() for x in arg.args]
p = [[], []]
n = len(arg.args)
for i in range(n, -1, -1):
p[(n - i) % 2].append(symmetric_poly(i, CX))
return Add(*p[0])/Add(*p[1])
elif arg.is_Mul:
from sympy import binomial
coeff, x = arg.as_coeff_Mul(rational=True)
if coeff.is_Integer and coeff > 1:
c = coth(x, evaluate=False)
p = [[], []]
for i in range(coeff, -1, -1):
p[(coeff - i) % 2].append(binomial(coeff, i)*c**i)
return Add(*p[0])/Add(*p[1])
return coth(arg)
class ReciprocalHyperbolicFunction(HyperbolicFunction):
"""Base class for reciprocal functions of hyperbolic functions. """
#To be defined in class
_reciprocal_of = None
_is_even = None # type: FuzzyBool
_is_odd = None # type: FuzzyBool
@classmethod
def eval(cls, arg):
if arg.could_extract_minus_sign():
if cls._is_even:
return cls(-arg)
if cls._is_odd:
return -cls(-arg)
t = cls._reciprocal_of.eval(arg)
if hasattr(arg, 'inverse') and arg.inverse() == cls:
return arg.args[0]
return 1/t if t is not None else t
def _call_reciprocal(self, method_name, *args, **kwargs):
# Calls method_name on _reciprocal_of
o = self._reciprocal_of(self.args[0])
return getattr(o, method_name)(*args, **kwargs)
def _calculate_reciprocal(self, method_name, *args, **kwargs):
# If calling method_name on _reciprocal_of returns a value != None
# then return the reciprocal of that value
t = self._call_reciprocal(method_name, *args, **kwargs)
return 1/t if t is not None else t
def _rewrite_reciprocal(self, method_name, arg):
# Special handling for rewrite functions. If reciprocal rewrite returns
# unmodified expression, then return None
t = self._call_reciprocal(method_name, arg)
if t is not None and t != self._reciprocal_of(arg):
return 1/t
def _eval_rewrite_as_exp(self, arg, **kwargs):
return self._rewrite_reciprocal("_eval_rewrite_as_exp", arg)
def _eval_rewrite_as_tractable(self, arg, limitvar=None, **kwargs):
return self._rewrite_reciprocal("_eval_rewrite_as_tractable", arg)
def _eval_rewrite_as_tanh(self, arg, **kwargs):
return self._rewrite_reciprocal("_eval_rewrite_as_tanh", arg)
def _eval_rewrite_as_coth(self, arg, **kwargs):
return self._rewrite_reciprocal("_eval_rewrite_as_coth", arg)
def as_real_imag(self, deep = True, **hints):
return (1 / self._reciprocal_of(self.args[0])).as_real_imag(deep, **hints)
def _eval_conjugate(self):
return self.func(self.args[0].conjugate())
def _eval_expand_complex(self, deep=True, **hints):
re_part, im_part = self.as_real_imag(deep=True, **hints)
return re_part + S.ImaginaryUnit*im_part
def _eval_expand_trig(self, **hints):
return self._calculate_reciprocal("_eval_expand_trig", **hints)
def _eval_as_leading_term(self, x, logx=None, cdir=0):
return (1/self._reciprocal_of(self.args[0]))._eval_as_leading_term(x)
def _eval_is_extended_real(self):
return self._reciprocal_of(self.args[0]).is_extended_real
def _eval_is_finite(self):
return (1/self._reciprocal_of(self.args[0])).is_finite
class csch(ReciprocalHyperbolicFunction):
r"""
csch(x) is the hyperbolic cosecant of x.
The hyperbolic cosecant function is $\frac{2}{e^x - e^{-x}}$
Examples
========
>>> from sympy import csch
>>> from sympy.abc import x
>>> csch(x)
csch(x)
See Also
========
sinh, cosh, tanh, sech, asinh, acosh
"""
_reciprocal_of = sinh
_is_odd = True
def fdiff(self, argindex=1):
"""
Returns the first derivative of this function
"""
if argindex == 1:
return -coth(self.args[0]) * csch(self.args[0])
else:
raise ArgumentIndexError(self, argindex)
@staticmethod
@cacheit
def taylor_term(n, x, *previous_terms):
"""
Returns the next term in the Taylor series expansion
"""
from sympy import bernoulli
if n == 0:
return 1/sympify(x)
elif n < 0 or n % 2 == 0:
return S.Zero
else:
x = sympify(x)
B = bernoulli(n + 1)
F = factorial(n + 1)
return 2 * (1 - 2**n) * B/F * x**n
def _eval_rewrite_as_cosh(self, arg, **kwargs):
return S.ImaginaryUnit / cosh(arg + S.ImaginaryUnit * S.Pi / 2)
def _eval_is_positive(self):
if self.args[0].is_extended_real:
return self.args[0].is_positive
def _eval_is_negative(self):
if self.args[0].is_extended_real:
return self.args[0].is_negative
def _sage_(self):
import sage.all as sage
return sage.csch(self.args[0]._sage_())
class sech(ReciprocalHyperbolicFunction):
r"""
sech(x) is the hyperbolic secant of x.
The hyperbolic secant function is $\frac{2}{e^x + e^{-x}}$
Examples
========
>>> from sympy import sech
>>> from sympy.abc import x
>>> sech(x)
sech(x)
See Also
========
sinh, cosh, tanh, coth, csch, asinh, acosh
"""
_reciprocal_of = cosh
_is_even = True
def fdiff(self, argindex=1):
if argindex == 1:
return - tanh(self.args[0])*sech(self.args[0])
else:
raise ArgumentIndexError(self, argindex)
@staticmethod
@cacheit
def taylor_term(n, x, *previous_terms):
from sympy.functions.combinatorial.numbers import euler
if n < 0 or n % 2 == 1:
return S.Zero
else:
x = sympify(x)
return euler(n) / factorial(n) * x**(n)
def _eval_rewrite_as_sinh(self, arg, **kwargs):
return S.ImaginaryUnit / sinh(arg + S.ImaginaryUnit * S.Pi /2)
def _eval_is_positive(self):
if self.args[0].is_extended_real:
return True
def _sage_(self):
import sage.all as sage
return sage.sech(self.args[0]._sage_())
###############################################################################
############################# HYPERBOLIC INVERSES #############################
###############################################################################
class InverseHyperbolicFunction(Function):
"""Base class for inverse hyperbolic functions."""
pass
class asinh(InverseHyperbolicFunction):
"""
asinh(x) is the inverse hyperbolic sine of x.
The inverse hyperbolic sine function.
Examples
========
>>> from sympy import asinh
>>> from sympy.abc import x
>>> asinh(x).diff(x)
1/sqrt(x**2 + 1)
>>> asinh(1)
log(1 + sqrt(2))
See Also
========
acosh, atanh, sinh
"""
def fdiff(self, argindex=1):
if argindex == 1:
return 1/sqrt(self.args[0]**2 + 1)
else:
raise ArgumentIndexError(self, argindex)
@classmethod
def eval(cls, arg):
from sympy import asin
arg = sympify(arg)
if arg.is_Number:
if arg is S.NaN:
return S.NaN
elif arg is S.Infinity:
return S.Infinity
elif arg is S.NegativeInfinity:
return S.NegativeInfinity
elif arg.is_zero:
return S.Zero
elif arg is S.One:
return log(sqrt(2) + 1)
elif arg is S.NegativeOne:
return log(sqrt(2) - 1)
elif arg.is_negative:
return -cls(-arg)
else:
if arg is S.ComplexInfinity:
return S.ComplexInfinity
if arg.is_zero:
return S.Zero
i_coeff = arg.as_coefficient(S.ImaginaryUnit)
if i_coeff is not None:
return S.ImaginaryUnit * asin(i_coeff)
else:
if _coeff_isneg(arg):
return -cls(-arg)
if isinstance(arg, sinh) and arg.args[0].is_number:
z = arg.args[0]
if z.is_real:
return z
r, i = match_real_imag(z)
if r is not None and i is not None:
f = floor((i + pi/2)/pi)
m = z - I*pi*f
even = f.is_even
if even is True:
return m
elif even is False:
return -m
@staticmethod
@cacheit
def taylor_term(n, x, *previous_terms):
if n < 0 or n % 2 == 0:
return S.Zero
else:
x = sympify(x)
if len(previous_terms) >= 2 and n > 2:
p = previous_terms[-2]
return -p * (n - 2)**2/(n*(n - 1)) * x**2
else:
k = (n - 1) // 2
R = RisingFactorial(S.Half, k)
F = factorial(k)
return (-1)**k * R / F * x**n / n
def _eval_as_leading_term(self, x, logx=None, cdir=0):
from sympy import Order
arg = self.args[0].as_leading_term(x)
if x in arg.free_symbols and Order(1, x).contains(arg):
return arg
else:
return self.func(arg)
def _eval_rewrite_as_log(self, x, **kwargs):
return log(x + sqrt(x**2 + 1))
def inverse(self, argindex=1):
"""
Returns the inverse of this function.
"""
return sinh
def _eval_is_zero(self):
arg = self.args[0]
if arg.is_zero:
return True
class acosh(InverseHyperbolicFunction):
"""
acosh(x) is the inverse hyperbolic cosine of x.
The inverse hyperbolic cosine function.
Examples
========
>>> from sympy import acosh
>>> from sympy.abc import x
>>> acosh(x).diff(x)
1/sqrt(x**2 - 1)
>>> acosh(1)
0
See Also
========
asinh, atanh, cosh
"""
def fdiff(self, argindex=1):
if argindex == 1:
return 1/sqrt(self.args[0]**2 - 1)
else:
raise ArgumentIndexError(self, argindex)
@classmethod
def eval(cls, arg):
arg = sympify(arg)
if arg.is_Number:
if arg is S.NaN:
return S.NaN
elif arg is S.Infinity:
return S.Infinity
elif arg is S.NegativeInfinity:
return S.Infinity
elif arg.is_zero:
return S.Pi*S.ImaginaryUnit / 2
elif arg is S.One:
return S.Zero
elif arg is S.NegativeOne:
return S.Pi*S.ImaginaryUnit
if arg.is_number:
cst_table = {
S.ImaginaryUnit: log(S.ImaginaryUnit*(1 + sqrt(2))),
-S.ImaginaryUnit: log(-S.ImaginaryUnit*(1 + sqrt(2))),
S.Half: S.Pi/3,
Rational(-1, 2): S.Pi*Rational(2, 3),
sqrt(2)/2: S.Pi/4,
-sqrt(2)/2: S.Pi*Rational(3, 4),
1/sqrt(2): S.Pi/4,
-1/sqrt(2): S.Pi*Rational(3, 4),
sqrt(3)/2: S.Pi/6,
-sqrt(3)/2: S.Pi*Rational(5, 6),
(sqrt(3) - 1)/sqrt(2**3): S.Pi*Rational(5, 12),
-(sqrt(3) - 1)/sqrt(2**3): S.Pi*Rational(7, 12),
sqrt(2 + sqrt(2))/2: S.Pi/8,
-sqrt(2 + sqrt(2))/2: S.Pi*Rational(7, 8),
sqrt(2 - sqrt(2))/2: S.Pi*Rational(3, 8),
-sqrt(2 - sqrt(2))/2: S.Pi*Rational(5, 8),
(1 + sqrt(3))/(2*sqrt(2)): S.Pi/12,
-(1 + sqrt(3))/(2*sqrt(2)): S.Pi*Rational(11, 12),
(sqrt(5) + 1)/4: S.Pi/5,
-(sqrt(5) + 1)/4: S.Pi*Rational(4, 5)
}
if arg in cst_table:
if arg.is_extended_real:
return cst_table[arg]*S.ImaginaryUnit
return cst_table[arg]
if arg is S.ComplexInfinity:
return S.ComplexInfinity
if arg == S.ImaginaryUnit*S.Infinity:
return S.Infinity + S.ImaginaryUnit*S.Pi/2
if arg == -S.ImaginaryUnit*S.Infinity:
return S.Infinity - S.ImaginaryUnit*S.Pi/2
if arg.is_zero:
return S.Pi*S.ImaginaryUnit*S.Half
if isinstance(arg, cosh) and arg.args[0].is_number:
z = arg.args[0]
if z.is_real:
from sympy.functions.elementary.complexes import Abs
return Abs(z)
r, i = match_real_imag(z)
if r is not None and i is not None:
f = floor(i/pi)
m = z - I*pi*f
even = f.is_even
if even is True:
if r.is_nonnegative:
return m
elif r.is_negative:
return -m
elif even is False:
m -= I*pi
if r.is_nonpositive:
return -m
elif r.is_positive:
return m
@staticmethod
@cacheit
def taylor_term(n, x, *previous_terms):
if n == 0:
return S.Pi*S.ImaginaryUnit / 2
elif n < 0 or n % 2 == 0:
return S.Zero
else:
x = sympify(x)
if len(previous_terms) >= 2 and n > 2:
p = previous_terms[-2]
return p * (n - 2)**2/(n*(n - 1)) * x**2
else:
k = (n - 1) // 2
R = RisingFactorial(S.Half, k)
F = factorial(k)
return -R / F * S.ImaginaryUnit * x**n / n
def _eval_as_leading_term(self, x, logx=None, cdir=0):
from sympy import Order
arg = self.args[0].as_leading_term(x)
if x in arg.free_symbols and Order(1, x).contains(arg):
return S.ImaginaryUnit*S.Pi/2
else:
return self.func(arg)
def _eval_rewrite_as_log(self, x, **kwargs):
return log(x + sqrt(x + 1) * sqrt(x - 1))
def inverse(self, argindex=1):
"""
Returns the inverse of this function.
"""
return cosh
class atanh(InverseHyperbolicFunction):
"""
atanh(x) is the inverse hyperbolic tangent of x.
The inverse hyperbolic tangent function.
Examples
========
>>> from sympy import atanh
>>> from sympy.abc import x
>>> atanh(x).diff(x)
1/(1 - x**2)
See Also
========
asinh, acosh, tanh
"""
def fdiff(self, argindex=1):
if argindex == 1:
return 1/(1 - self.args[0]**2)
else:
raise ArgumentIndexError(self, argindex)
@classmethod
def eval(cls, arg):
from sympy import atan
arg = sympify(arg)
if arg.is_Number:
if arg is S.NaN:
return S.NaN
elif arg.is_zero:
return S.Zero
elif arg is S.One:
return S.Infinity
elif arg is S.NegativeOne:
return S.NegativeInfinity
elif arg is S.Infinity:
return -S.ImaginaryUnit * atan(arg)
elif arg is S.NegativeInfinity:
return S.ImaginaryUnit * atan(-arg)
elif arg.is_negative:
return -cls(-arg)
else:
if arg is S.ComplexInfinity:
from sympy.calculus.util import AccumBounds
return S.ImaginaryUnit*AccumBounds(-S.Pi/2, S.Pi/2)
i_coeff = arg.as_coefficient(S.ImaginaryUnit)
if i_coeff is not None:
return S.ImaginaryUnit * atan(i_coeff)
else:
if _coeff_isneg(arg):
return -cls(-arg)
if arg.is_zero:
return S.Zero
if isinstance(arg, tanh) and arg.args[0].is_number:
z = arg.args[0]
if z.is_real:
return z
r, i = match_real_imag(z)
if r is not None and i is not None:
f = floor(2*i/pi)
even = f.is_even
m = z - I*f*pi/2
if even is True:
return m
elif even is False:
return m - I*pi/2
@staticmethod
@cacheit
def taylor_term(n, x, *previous_terms):
if n < 0 or n % 2 == 0:
return S.Zero
else:
x = sympify(x)
return x**n / n
def _eval_as_leading_term(self, x, logx=None, cdir=0):
from sympy import Order
arg = self.args[0].as_leading_term(x)
if x in arg.free_symbols and Order(1, x).contains(arg):
return arg
else:
return self.func(arg)
def _eval_rewrite_as_log(self, x, **kwargs):
return (log(1 + x) - log(1 - x)) / 2
def _eval_is_zero(self):
arg = self.args[0]
if arg.is_zero:
return True
def inverse(self, argindex=1):
"""
Returns the inverse of this function.
"""
return tanh
class acoth(InverseHyperbolicFunction):
"""
acoth(x) is the inverse hyperbolic cotangent of x.
The inverse hyperbolic cotangent function.
Examples
========
>>> from sympy import acoth
>>> from sympy.abc import x
>>> acoth(x).diff(x)
1/(1 - x**2)
See Also
========
asinh, acosh, coth
"""
def fdiff(self, argindex=1):
if argindex == 1:
return 1/(1 - self.args[0]**2)
else:
raise ArgumentIndexError(self, argindex)
@classmethod
def eval(cls, arg):
from sympy import acot
arg = sympify(arg)
if arg.is_Number:
if arg is S.NaN:
return S.NaN
elif arg is S.Infinity:
return S.Zero
elif arg is S.NegativeInfinity:
return S.Zero
elif arg.is_zero:
return S.Pi*S.ImaginaryUnit / 2
elif arg is S.One:
return S.Infinity
elif arg is S.NegativeOne:
return S.NegativeInfinity
elif arg.is_negative:
return -cls(-arg)
else:
if arg is S.ComplexInfinity:
return S.Zero
i_coeff = arg.as_coefficient(S.ImaginaryUnit)
if i_coeff is not None:
return -S.ImaginaryUnit * acot(i_coeff)
else:
if _coeff_isneg(arg):
return -cls(-arg)
if arg.is_zero:
return S.Pi*S.ImaginaryUnit*S.Half
@staticmethod
@cacheit
def taylor_term(n, x, *previous_terms):
if n == 0:
return S.Pi*S.ImaginaryUnit / 2
elif n < 0 or n % 2 == 0:
return S.Zero
else:
x = sympify(x)
return x**n / n
def _eval_as_leading_term(self, x, logx=None, cdir=0):
from sympy import Order
arg = self.args[0].as_leading_term(x)
if x in arg.free_symbols and Order(1, x).contains(arg):
return S.ImaginaryUnit*S.Pi/2
else:
return self.func(arg)
def _eval_rewrite_as_log(self, x, **kwargs):
return (log(1 + 1/x) - log(1 - 1/x)) / 2
def inverse(self, argindex=1):
"""
Returns the inverse of this function.
"""
return coth
class asech(InverseHyperbolicFunction):
"""
asech(x) is the inverse hyperbolic secant of x.
The inverse hyperbolic secant function.
Examples
========
>>> from sympy import asech, sqrt, S
>>> from sympy.abc import x
>>> asech(x).diff(x)
-1/(x*sqrt(1 - x**2))
>>> asech(1).diff(x)
0
>>> asech(1)
0
>>> asech(S(2))
I*pi/3
>>> asech(-sqrt(2))
3*I*pi/4
>>> asech((sqrt(6) - sqrt(2)))
I*pi/12
See Also
========
asinh, atanh, cosh, acoth
References
==========
.. [1] https://en.wikipedia.org/wiki/Hyperbolic_function
.. [2] http://dlmf.nist.gov/4.37
.. [3] http://functions.wolfram.com/ElementaryFunctions/ArcSech/
"""
def fdiff(self, argindex=1):
if argindex == 1:
z = self.args[0]
return -1/(z*sqrt(1 - z**2))
else:
raise ArgumentIndexError(self, argindex)
@classmethod
def eval(cls, arg):
arg = sympify(arg)
if arg.is_Number:
if arg is S.NaN:
return S.NaN
elif arg is S.Infinity:
return S.Pi*S.ImaginaryUnit / 2
elif arg is S.NegativeInfinity:
return S.Pi*S.ImaginaryUnit / 2
elif arg.is_zero:
return S.Infinity
elif arg is S.One:
return S.Zero
elif arg is S.NegativeOne:
return S.Pi*S.ImaginaryUnit
if arg.is_number:
cst_table = {
S.ImaginaryUnit: - (S.Pi*S.ImaginaryUnit / 2) + log(1 + sqrt(2)),
-S.ImaginaryUnit: (S.Pi*S.ImaginaryUnit / 2) + log(1 + sqrt(2)),
(sqrt(6) - sqrt(2)): S.Pi / 12,
(sqrt(2) - sqrt(6)): 11*S.Pi / 12,
sqrt(2 - 2/sqrt(5)): S.Pi / 10,
-sqrt(2 - 2/sqrt(5)): 9*S.Pi / 10,
2 / sqrt(2 + sqrt(2)): S.Pi / 8,
-2 / sqrt(2 + sqrt(2)): 7*S.Pi / 8,
2 / sqrt(3): S.Pi / 6,
-2 / sqrt(3): 5*S.Pi / 6,
(sqrt(5) - 1): S.Pi / 5,
(1 - sqrt(5)): 4*S.Pi / 5,
sqrt(2): S.Pi / 4,
-sqrt(2): 3*S.Pi / 4,
sqrt(2 + 2/sqrt(5)): 3*S.Pi / 10,
-sqrt(2 + 2/sqrt(5)): 7*S.Pi / 10,
S(2): S.Pi / 3,
-S(2): 2*S.Pi / 3,
sqrt(2*(2 + sqrt(2))): 3*S.Pi / 8,
-sqrt(2*(2 + sqrt(2))): 5*S.Pi / 8,
(1 + sqrt(5)): 2*S.Pi / 5,
(-1 - sqrt(5)): 3*S.Pi / 5,
(sqrt(6) + sqrt(2)): 5*S.Pi / 12,
(-sqrt(6) - sqrt(2)): 7*S.Pi / 12,
}
if arg in cst_table:
if arg.is_extended_real:
return cst_table[arg]*S.ImaginaryUnit
return cst_table[arg]
if arg is S.ComplexInfinity:
from sympy.calculus.util import AccumBounds
return S.ImaginaryUnit*AccumBounds(-S.Pi/2, S.Pi/2)
if arg.is_zero:
return S.Infinity
@staticmethod
@cacheit
def expansion_term(n, x, *previous_terms):
if n == 0:
return log(2 / x)
elif n < 0 or n % 2 == 1:
return S.Zero
else:
x = sympify(x)
if len(previous_terms) > 2 and n > 2:
p = previous_terms[-2]
return p * (n - 1)**2 // (n // 2)**2 * x**2 / 4
else:
k = n // 2
R = RisingFactorial(S.Half , k) * n
F = factorial(k) * n // 2 * n // 2
return -1 * R / F * x**n / 4
def inverse(self, argindex=1):
"""
Returns the inverse of this function.
"""
return sech
def _eval_rewrite_as_log(self, arg, **kwargs):
return log(1/arg + sqrt(1/arg - 1) * sqrt(1/arg + 1))
class acsch(InverseHyperbolicFunction):
"""
acsch(x) is the inverse hyperbolic cosecant of x.
The inverse hyperbolic cosecant function.
Examples
========
>>> from sympy import acsch, sqrt, S
>>> from sympy.abc import x
>>> acsch(x).diff(x)
-1/(x**2*sqrt(1 + x**(-2)))
>>> acsch(1).diff(x)
0
>>> acsch(1)
log(1 + sqrt(2))
>>> acsch(S.ImaginaryUnit)
-I*pi/2
>>> acsch(-2*S.ImaginaryUnit)
I*pi/6
>>> acsch(S.ImaginaryUnit*(sqrt(6) - sqrt(2)))
-5*I*pi/12
See Also
========
asinh
References
==========
.. [1] https://en.wikipedia.org/wiki/Hyperbolic_function
.. [2] http://dlmf.nist.gov/4.37
.. [3] http://functions.wolfram.com/ElementaryFunctions/ArcCsch/
"""
def fdiff(self, argindex=1):
if argindex == 1:
z = self.args[0]
return -1/(z**2*sqrt(1 + 1/z**2))
else:
raise ArgumentIndexError(self, argindex)
@classmethod
def eval(cls, arg):
arg = sympify(arg)
if arg.is_Number:
if arg is S.NaN:
return S.NaN
elif arg is S.Infinity:
return S.Zero
elif arg is S.NegativeInfinity:
return S.Zero
elif arg.is_zero:
return S.ComplexInfinity
elif arg is S.One:
return log(1 + sqrt(2))
elif arg is S.NegativeOne:
return - log(1 + sqrt(2))
if arg.is_number:
cst_table = {
S.ImaginaryUnit: -S.Pi / 2,
S.ImaginaryUnit*(sqrt(2) + sqrt(6)): -S.Pi / 12,
S.ImaginaryUnit*(1 + sqrt(5)): -S.Pi / 10,
S.ImaginaryUnit*2 / sqrt(2 - sqrt(2)): -S.Pi / 8,
S.ImaginaryUnit*2: -S.Pi / 6,
S.ImaginaryUnit*sqrt(2 + 2/sqrt(5)): -S.Pi / 5,
S.ImaginaryUnit*sqrt(2): -S.Pi / 4,
S.ImaginaryUnit*(sqrt(5)-1): -3*S.Pi / 10,
S.ImaginaryUnit*2 / sqrt(3): -S.Pi / 3,
S.ImaginaryUnit*2 / sqrt(2 + sqrt(2)): -3*S.Pi / 8,
S.ImaginaryUnit*sqrt(2 - 2/sqrt(5)): -2*S.Pi / 5,
S.ImaginaryUnit*(sqrt(6) - sqrt(2)): -5*S.Pi / 12,
S(2): -S.ImaginaryUnit*log((1+sqrt(5))/2),
}
if arg in cst_table:
return cst_table[arg]*S.ImaginaryUnit
if arg is S.ComplexInfinity:
return S.Zero
if arg.is_zero:
return S.ComplexInfinity
if _coeff_isneg(arg):
return -cls(-arg)
def inverse(self, argindex=1):
"""
Returns the inverse of this function.
"""
return csch
def _eval_rewrite_as_log(self, arg, **kwargs):
return log(1/arg + sqrt(1/arg**2 + 1))
|
979432ea666e3616bc1ab07c20abd26b53f035584791be9f5f2153abf36835a4 | from sympy.core import S, Add, Mul, sympify, Symbol, Dummy, Basic
from sympy.core.expr import Expr
from sympy.core.exprtools import factor_terms
from sympy.core.function import (Function, Derivative, ArgumentIndexError,
AppliedUndef)
from sympy.core.logic import fuzzy_not, fuzzy_or
from sympy.core.numbers import pi, I, oo
from sympy.core.relational import Eq
from sympy.functions.elementary.exponential import exp, exp_polar, log
from sympy.functions.elementary.integers import ceiling
from sympy.functions.elementary.miscellaneous import sqrt
from sympy.functions.elementary.piecewise import Piecewise
from sympy.functions.elementary.trigonometric import atan, atan2
###############################################################################
######################### REAL and IMAGINARY PARTS ############################
###############################################################################
class re(Function):
"""
Returns real part of expression. This function performs only
elementary analysis and so it will fail to decompose properly
more complicated expressions. If completely simplified result
is needed then use Basic.as_real_imag() or perform complex
expansion on instance of this function.
Examples
========
>>> from sympy import re, im, I, E, symbols
>>> x, y = symbols('x y', real=True)
>>> re(2*E)
2*E
>>> re(2*I + 17)
17
>>> re(2*I)
0
>>> re(im(x) + x*I + 2)
2
>>> re(5 + I + 2)
7
Parameters
==========
arg : Expr
Real or complex expression.
Returns
=======
expr : Expr
Real part of expression.
See Also
========
im
"""
is_extended_real = True
unbranched = True # implicitly works on the projection to C
_singularities = True # non-holomorphic
@classmethod
def eval(cls, arg):
if arg is S.NaN:
return S.NaN
elif arg is S.ComplexInfinity:
return S.NaN
elif arg.is_extended_real:
return arg
elif arg.is_imaginary or (S.ImaginaryUnit*arg).is_extended_real:
return S.Zero
elif arg.is_Matrix:
return arg.as_real_imag()[0]
elif arg.is_Function and isinstance(arg, conjugate):
return re(arg.args[0])
else:
included, reverted, excluded = [], [], []
args = Add.make_args(arg)
for term in args:
coeff = term.as_coefficient(S.ImaginaryUnit)
if coeff is not None:
if not coeff.is_extended_real:
reverted.append(coeff)
elif not term.has(S.ImaginaryUnit) and term.is_extended_real:
excluded.append(term)
else:
# Try to do some advanced expansion. If
# impossible, don't try to do re(arg) again
# (because this is what we are trying to do now).
real_imag = term.as_real_imag(ignore=arg)
if real_imag:
excluded.append(real_imag[0])
else:
included.append(term)
if len(args) != len(included):
a, b, c = (Add(*xs) for xs in [included, reverted, excluded])
return cls(a) - im(b) + c
def as_real_imag(self, deep=True, **hints):
"""
Returns the real number with a zero imaginary part.
"""
return (self, S.Zero)
def _eval_derivative(self, x):
if x.is_extended_real or self.args[0].is_extended_real:
return re(Derivative(self.args[0], x, evaluate=True))
if x.is_imaginary or self.args[0].is_imaginary:
return -S.ImaginaryUnit \
* im(Derivative(self.args[0], x, evaluate=True))
def _eval_rewrite_as_im(self, arg, **kwargs):
return self.args[0] - S.ImaginaryUnit*im(self.args[0])
def _eval_is_algebraic(self):
return self.args[0].is_algebraic
def _eval_is_zero(self):
# is_imaginary implies nonzero
return fuzzy_or([self.args[0].is_imaginary, self.args[0].is_zero])
def _eval_is_finite(self):
if self.args[0].is_finite:
return True
def _eval_is_complex(self):
if self.args[0].is_finite:
return True
def _sage_(self):
import sage.all as sage
return sage.real_part(self.args[0]._sage_())
class im(Function):
"""
Returns imaginary part of expression. This function performs only
elementary analysis and so it will fail to decompose properly more
complicated expressions. If completely simplified result is needed then
use Basic.as_real_imag() or perform complex expansion on instance of
this function.
Examples
========
>>> from sympy import re, im, E, I
>>> from sympy.abc import x, y
>>> im(2*E)
0
>>> im(2*I + 17)
2
>>> im(x*I)
re(x)
>>> im(re(x) + y)
im(y)
>>> im(2 + 3*I)
3
Parameters
==========
arg : Expr
Real or complex expression.
Returns
=======
expr : Expr
Imaginary part of expression.
See Also
========
re
"""
is_extended_real = True
unbranched = True # implicitly works on the projection to C
_singularities = True # non-holomorphic
@classmethod
def eval(cls, arg):
if arg is S.NaN:
return S.NaN
elif arg is S.ComplexInfinity:
return S.NaN
elif arg.is_extended_real:
return S.Zero
elif arg.is_imaginary or (S.ImaginaryUnit*arg).is_extended_real:
return -S.ImaginaryUnit * arg
elif arg.is_Matrix:
return arg.as_real_imag()[1]
elif arg.is_Function and isinstance(arg, conjugate):
return -im(arg.args[0])
else:
included, reverted, excluded = [], [], []
args = Add.make_args(arg)
for term in args:
coeff = term.as_coefficient(S.ImaginaryUnit)
if coeff is not None:
if not coeff.is_extended_real:
reverted.append(coeff)
else:
excluded.append(coeff)
elif term.has(S.ImaginaryUnit) or not term.is_extended_real:
# Try to do some advanced expansion. If
# impossible, don't try to do im(arg) again
# (because this is what we are trying to do now).
real_imag = term.as_real_imag(ignore=arg)
if real_imag:
excluded.append(real_imag[1])
else:
included.append(term)
if len(args) != len(included):
a, b, c = (Add(*xs) for xs in [included, reverted, excluded])
return cls(a) + re(b) + c
def as_real_imag(self, deep=True, **hints):
"""
Return the imaginary part with a zero real part.
"""
return (self, S.Zero)
def _eval_derivative(self, x):
if x.is_extended_real or self.args[0].is_extended_real:
return im(Derivative(self.args[0], x, evaluate=True))
if x.is_imaginary or self.args[0].is_imaginary:
return -S.ImaginaryUnit \
* re(Derivative(self.args[0], x, evaluate=True))
def _sage_(self):
import sage.all as sage
return sage.imag_part(self.args[0]._sage_())
def _eval_rewrite_as_re(self, arg, **kwargs):
return -S.ImaginaryUnit*(self.args[0] - re(self.args[0]))
def _eval_is_algebraic(self):
return self.args[0].is_algebraic
def _eval_is_zero(self):
return self.args[0].is_extended_real
def _eval_is_finite(self):
if self.args[0].is_finite:
return True
def _eval_is_complex(self):
if self.args[0].is_finite:
return True
###############################################################################
############### SIGN, ABSOLUTE VALUE, ARGUMENT and CONJUGATION ################
###############################################################################
class sign(Function):
"""
Returns the complex sign of an expression:
Explanation
===========
If the expression is real the sign will be:
* 1 if expression is positive
* 0 if expression is equal to zero
* -1 if expression is negative
If the expression is imaginary the sign will be:
* I if im(expression) is positive
* -I if im(expression) is negative
Otherwise an unevaluated expression will be returned. When evaluated, the
result (in general) will be ``cos(arg(expr)) + I*sin(arg(expr))``.
Examples
========
>>> from sympy.functions import sign
>>> from sympy.core.numbers import I
>>> sign(-1)
-1
>>> sign(0)
0
>>> sign(-3*I)
-I
>>> sign(1 + I)
sign(1 + I)
>>> _.evalf()
0.707106781186548 + 0.707106781186548*I
Parameters
==========
arg : Expr
Real or imaginary expression.
Returns
=======
expr : Expr
Complex sign of expression.
See Also
========
Abs, conjugate
"""
is_complex = True
_singularities = True
def doit(self, **hints):
if self.args[0].is_zero is False:
return self.args[0] / Abs(self.args[0])
return self
@classmethod
def eval(cls, arg):
# handle what we can
if arg.is_Mul:
c, args = arg.as_coeff_mul()
unk = []
s = sign(c)
for a in args:
if a.is_extended_negative:
s = -s
elif a.is_extended_positive:
pass
else:
if a.is_imaginary:
ai = im(a)
if ai.is_comparable: # i.e. a = I*real
s *= S.ImaginaryUnit
if ai.is_extended_negative:
# can't use sign(ai) here since ai might not be
# a Number
s = -s
else:
unk.append(a)
else:
unk.append(a)
if c is S.One and len(unk) == len(args):
return None
return s * cls(arg._new_rawargs(*unk))
if arg is S.NaN:
return S.NaN
if arg.is_zero: # it may be an Expr that is zero
return S.Zero
if arg.is_extended_positive:
return S.One
if arg.is_extended_negative:
return S.NegativeOne
if arg.is_Function:
if isinstance(arg, sign):
return arg
if arg.is_imaginary:
if arg.is_Pow and arg.exp is S.Half:
# we catch this because non-trivial sqrt args are not expanded
# e.g. sqrt(1-sqrt(2)) --x--> to I*sqrt(sqrt(2) - 1)
return S.ImaginaryUnit
arg2 = -S.ImaginaryUnit * arg
if arg2.is_extended_positive:
return S.ImaginaryUnit
if arg2.is_extended_negative:
return -S.ImaginaryUnit
def _eval_Abs(self):
if fuzzy_not(self.args[0].is_zero):
return S.One
def _eval_conjugate(self):
return sign(conjugate(self.args[0]))
def _eval_derivative(self, x):
if self.args[0].is_extended_real:
from sympy.functions.special.delta_functions import DiracDelta
return 2 * Derivative(self.args[0], x, evaluate=True) \
* DiracDelta(self.args[0])
elif self.args[0].is_imaginary:
from sympy.functions.special.delta_functions import DiracDelta
return 2 * Derivative(self.args[0], x, evaluate=True) \
* DiracDelta(-S.ImaginaryUnit * self.args[0])
def _eval_is_nonnegative(self):
if self.args[0].is_nonnegative:
return True
def _eval_is_nonpositive(self):
if self.args[0].is_nonpositive:
return True
def _eval_is_imaginary(self):
return self.args[0].is_imaginary
def _eval_is_integer(self):
return self.args[0].is_extended_real
def _eval_is_zero(self):
return self.args[0].is_zero
def _eval_power(self, other):
if (
fuzzy_not(self.args[0].is_zero) and
other.is_integer and
other.is_even
):
return S.One
def _eval_nseries(self, x, n, logx, cdir=0):
arg0 = self.args[0]
x0 = arg0.subs(x, 0)
if x0 != 0:
return self.func(x0)
if cdir != 0:
cdir = arg0.dir(x, cdir)
return -S.One if re(cdir) < 0 else S.One
def _sage_(self):
import sage.all as sage
return sage.sgn(self.args[0]._sage_())
def _eval_rewrite_as_Piecewise(self, arg, **kwargs):
if arg.is_extended_real:
return Piecewise((1, arg > 0), (-1, arg < 0), (0, True))
def _eval_rewrite_as_Heaviside(self, arg, **kwargs):
from sympy.functions.special.delta_functions import Heaviside
if arg.is_extended_real:
return Heaviside(arg) * 2 - 1
def _eval_rewrite_as_Abs(self, arg, **kwargs):
return Piecewise((0, Eq(arg, 0)), (arg / Abs(arg), True))
def _eval_simplify(self, **kwargs):
return self.func(factor_terms(self.args[0])) # XXX include doit?
class Abs(Function):
"""
Return the absolute value of the argument.
Explanation
===========
This is an extension of the built-in function abs() to accept symbolic
values. If you pass a SymPy expression to the built-in abs(), it will
pass it automatically to Abs().
Examples
========
>>> from sympy import Abs, Symbol, S, I
>>> Abs(-1)
1
>>> x = Symbol('x', real=True)
>>> Abs(-x)
Abs(x)
>>> Abs(x**2)
x**2
>>> abs(-x) # The Python built-in
Abs(x)
>>> Abs(3*x + 2*I)
sqrt(9*x**2 + 4)
>>> Abs(8*I)
8
Note that the Python built-in will return either an Expr or int depending on
the argument::
>>> type(abs(-1))
<... 'int'>
>>> type(abs(S.NegativeOne))
<class 'sympy.core.numbers.One'>
Abs will always return a sympy object.
Parameters
==========
arg : Expr
Real or complex expression.
Returns
=======
expr : Expr
Absolute value returned can be an expression or integer depending on
input arg.
See Also
========
sign, conjugate
"""
is_extended_real = True
is_extended_negative = False
is_extended_nonnegative = True
unbranched = True
_singularities = True # non-holomorphic
def fdiff(self, argindex=1):
"""
Get the first derivative of the argument to Abs().
"""
if argindex == 1:
return sign(self.args[0])
else:
raise ArgumentIndexError(self, argindex)
@classmethod
def eval(cls, arg):
from sympy.simplify.simplify import signsimp
from sympy.core.function import expand_mul
from sympy.core.power import Pow
if hasattr(arg, '_eval_Abs'):
obj = arg._eval_Abs()
if obj is not None:
return obj
if not isinstance(arg, Expr):
raise TypeError("Bad argument type for Abs(): %s" % type(arg))
# handle what we can
arg = signsimp(arg, evaluate=False)
n, d = arg.as_numer_denom()
if d.free_symbols and not n.free_symbols:
return cls(n)/cls(d)
if arg.is_Mul:
known = []
unk = []
for t in arg.args:
if t.is_Pow and t.exp.is_integer and t.exp.is_negative:
bnew = cls(t.base)
if isinstance(bnew, cls):
unk.append(t)
else:
known.append(Pow(bnew, t.exp))
else:
tnew = cls(t)
if isinstance(tnew, cls):
unk.append(t)
else:
known.append(tnew)
known = Mul(*known)
unk = cls(Mul(*unk), evaluate=False) if unk else S.One
return known*unk
if arg is S.NaN:
return S.NaN
if arg is S.ComplexInfinity:
return S.Infinity
if arg.is_Pow:
base, exponent = arg.as_base_exp()
if base.is_extended_real:
if exponent.is_integer:
if exponent.is_even:
return arg
if base is S.NegativeOne:
return S.One
return Abs(base)**exponent
if base.is_extended_nonnegative:
return base**re(exponent)
if base.is_extended_negative:
return (-base)**re(exponent)*exp(-S.Pi*im(exponent))
return
elif not base.has(Symbol): # complex base
# express base**exponent as exp(exponent*log(base))
a, b = log(base).as_real_imag()
z = a + I*b
return exp(re(exponent*z))
if isinstance(arg, exp):
return exp(re(arg.args[0]))
if isinstance(arg, AppliedUndef):
if arg.is_positive:
return arg
elif arg.is_negative:
return -arg
return
if arg.is_Add and arg.has(S.Infinity, S.NegativeInfinity):
if any(a.is_infinite for a in arg.as_real_imag()):
return S.Infinity
if arg.is_zero:
return S.Zero
if arg.is_extended_nonnegative:
return arg
if arg.is_extended_nonpositive:
return -arg
if arg.is_imaginary:
arg2 = -S.ImaginaryUnit * arg
if arg2.is_extended_nonnegative:
return arg2
if arg.is_extended_real:
return
# reject result if all new conjugates are just wrappers around
# an expression that was already in the arg
conj = signsimp(arg.conjugate(), evaluate=False)
new_conj = conj.atoms(conjugate) - arg.atoms(conjugate)
if new_conj and all(arg.has(i.args[0]) for i in new_conj):
return
if arg != conj and arg != -conj:
ignore = arg.atoms(Abs)
abs_free_arg = arg.xreplace({i: Dummy(real=True) for i in ignore})
unk = [a for a in abs_free_arg.free_symbols if a.is_extended_real is None]
if not unk or not all(conj.has(conjugate(u)) for u in unk):
return sqrt(expand_mul(arg*conj))
def _eval_is_real(self):
if self.args[0].is_finite:
return True
def _eval_is_integer(self):
if self.args[0].is_extended_real:
return self.args[0].is_integer
def _eval_is_extended_nonzero(self):
return fuzzy_not(self._args[0].is_zero)
def _eval_is_zero(self):
return self._args[0].is_zero
def _eval_is_extended_positive(self):
is_z = self.is_zero
if is_z is not None:
return not is_z
def _eval_is_rational(self):
if self.args[0].is_extended_real:
return self.args[0].is_rational
def _eval_is_even(self):
if self.args[0].is_extended_real:
return self.args[0].is_even
def _eval_is_odd(self):
if self.args[0].is_extended_real:
return self.args[0].is_odd
def _eval_is_algebraic(self):
return self.args[0].is_algebraic
def _eval_power(self, exponent):
if self.args[0].is_extended_real and exponent.is_integer:
if exponent.is_even:
return self.args[0]**exponent
elif exponent is not S.NegativeOne and exponent.is_Integer:
return self.args[0]**(exponent - 1)*self
return
def _eval_nseries(self, x, n, logx, cdir=0):
direction = self.args[0].leadterm(x)[0]
if direction.has(log(x)):
direction = direction.subs(log(x), logx)
s = self.args[0]._eval_nseries(x, n=n, logx=logx)
return (sign(direction)*s).expand()
def _sage_(self):
import sage.all as sage
return sage.abs_symbolic(self.args[0]._sage_())
def _eval_derivative(self, x):
if self.args[0].is_extended_real or self.args[0].is_imaginary:
return Derivative(self.args[0], x, evaluate=True) \
* sign(conjugate(self.args[0]))
rv = (re(self.args[0]) * Derivative(re(self.args[0]), x,
evaluate=True) + im(self.args[0]) * Derivative(im(self.args[0]),
x, evaluate=True)) / Abs(self.args[0])
return rv.rewrite(sign)
def _eval_rewrite_as_Heaviside(self, arg, **kwargs):
# Note this only holds for real arg (since Heaviside is not defined
# for complex arguments).
from sympy.functions.special.delta_functions import Heaviside
if arg.is_extended_real:
return arg*(Heaviside(arg) - Heaviside(-arg))
def _eval_rewrite_as_Piecewise(self, arg, **kwargs):
if arg.is_extended_real:
return Piecewise((arg, arg >= 0), (-arg, True))
elif arg.is_imaginary:
return Piecewise((I*arg, I*arg >= 0), (-I*arg, True))
def _eval_rewrite_as_sign(self, arg, **kwargs):
return arg/sign(arg)
def _eval_rewrite_as_conjugate(self, arg, **kwargs):
return (arg*conjugate(arg))**S.Half
class arg(Function):
"""
returns the argument (in radians) of a complex number. The argument is
evaluated in consistent convention with atan2 where the branch-cut is
taken along the negative real axis and arg(z) is in the interval
(-pi,pi]. For a positive number, the argument is always 0.
Examples
========
>>> from sympy.functions import arg
>>> from sympy import I, sqrt
>>> arg(2.0)
0
>>> arg(I)
pi/2
>>> arg(sqrt(2) + I*sqrt(2))
pi/4
>>> arg(sqrt(3)/2 + I/2)
pi/6
>>> arg(4 + 3*I)
atan(3/4)
>>> arg(0.8 + 0.6*I)
0.643501108793284
Parameters
==========
arg : Expr
Real or complex expression.
Returns
=======
value : Expr
Returns arc tangent of arg measured in radians.
"""
is_extended_real = True
is_real = True
is_finite = True
_singularities = True # non-holomorphic
@classmethod
def eval(cls, arg):
if isinstance(arg, exp_polar):
return periodic_argument(arg, oo)
if not arg.is_Atom:
c, arg_ = factor_terms(arg).as_coeff_Mul()
if arg_.is_Mul:
arg_ = Mul(*[a if (sign(a) not in (-1, 1)) else
sign(a) for a in arg_.args])
arg_ = sign(c)*arg_
else:
arg_ = arg
if any(i.is_extended_positive is None for i in arg_.atoms(AppliedUndef)):
return
x, y = arg_.as_real_imag()
rv = atan2(y, x)
if rv.is_number:
return rv
if arg_ != arg:
return cls(arg_, evaluate=False)
def _eval_derivative(self, t):
x, y = self.args[0].as_real_imag()
return (x * Derivative(y, t, evaluate=True) - y *
Derivative(x, t, evaluate=True)) / (x**2 + y**2)
def _eval_rewrite_as_atan2(self, arg, **kwargs):
x, y = self.args[0].as_real_imag()
return atan2(y, x)
class conjugate(Function):
"""
Returns the `complex conjugate` Ref[1] of an argument.
In mathematics, the complex conjugate of a complex number
is given by changing the sign of the imaginary part.
Thus, the conjugate of the complex number
:math:`a + ib` (where a and b are real numbers) is :math:`a - ib`
Examples
========
>>> from sympy import conjugate, I
>>> conjugate(2)
2
>>> conjugate(I)
-I
>>> conjugate(3 + 2*I)
3 - 2*I
>>> conjugate(5 - I)
5 + I
Parameters
==========
arg : Expr
Real or complex expression.
Returns
=======
arg : Expr
Complex conjugate of arg as real, imaginary or mixed expression.
See Also
========
sign, Abs
References
==========
.. [1] https://en.wikipedia.org/wiki/Complex_conjugation
"""
_singularities = True # non-holomorphic
@classmethod
def eval(cls, arg):
obj = arg._eval_conjugate()
if obj is not None:
return obj
def _eval_Abs(self):
return Abs(self.args[0], evaluate=True)
def _eval_adjoint(self):
return transpose(self.args[0])
def _eval_conjugate(self):
return self.args[0]
def _eval_derivative(self, x):
if x.is_real:
return conjugate(Derivative(self.args[0], x, evaluate=True))
elif x.is_imaginary:
return -conjugate(Derivative(self.args[0], x, evaluate=True))
def _eval_transpose(self):
return adjoint(self.args[0])
def _eval_is_algebraic(self):
return self.args[0].is_algebraic
class transpose(Function):
"""
Linear map transposition.
Examples
========
>>> from sympy.functions import transpose
>>> from sympy.matrices import MatrixSymbol
>>> from sympy import Matrix
>>> A = MatrixSymbol('A', 25, 9)
>>> transpose(A)
A.T
>>> B = MatrixSymbol('B', 9, 22)
>>> transpose(B)
B.T
>>> transpose(A*B)
B.T*A.T
>>> M = Matrix([[4, 5], [2, 1], [90, 12]])
>>> M
Matrix([
[ 4, 5],
[ 2, 1],
[90, 12]])
>>> transpose(M)
Matrix([
[4, 2, 90],
[5, 1, 12]])
Parameters
==========
arg : Matrix
Matrix or matrix expression to take the transpose of.
Returns
=======
value : Matrix
Transpose of arg.
"""
@classmethod
def eval(cls, arg):
obj = arg._eval_transpose()
if obj is not None:
return obj
def _eval_adjoint(self):
return conjugate(self.args[0])
def _eval_conjugate(self):
return adjoint(self.args[0])
def _eval_transpose(self):
return self.args[0]
class adjoint(Function):
"""
Conjugate transpose or Hermite conjugation.
Examples
========
>>> from sympy import adjoint
>>> from sympy.matrices import MatrixSymbol
>>> A = MatrixSymbol('A', 10, 5)
>>> adjoint(A)
Adjoint(A)
Parameters
==========
arg : Matrix
Matrix or matrix expression to take the adjoint of.
Returns
=======
value : Matrix
Represents the conjugate transpose or Hermite
conjugation of arg.
"""
@classmethod
def eval(cls, arg):
obj = arg._eval_adjoint()
if obj is not None:
return obj
obj = arg._eval_transpose()
if obj is not None:
return conjugate(obj)
def _eval_adjoint(self):
return self.args[0]
def _eval_conjugate(self):
return transpose(self.args[0])
def _eval_transpose(self):
return conjugate(self.args[0])
def _latex(self, printer, exp=None, *args):
arg = printer._print(self.args[0])
tex = r'%s^{\dagger}' % arg
if exp:
tex = r'\left(%s\right)^{%s}' % (tex, exp)
return tex
def _pretty(self, printer, *args):
from sympy.printing.pretty.stringpict import prettyForm
pform = printer._print(self.args[0], *args)
if printer._use_unicode:
pform = pform**prettyForm('\N{DAGGER}')
else:
pform = pform**prettyForm('+')
return pform
###############################################################################
############### HANDLING OF POLAR NUMBERS #####################################
###############################################################################
class polar_lift(Function):
"""
Lift argument to the Riemann surface of the logarithm, using the
standard branch.
Examples
========
>>> from sympy import Symbol, polar_lift, I
>>> p = Symbol('p', polar=True)
>>> x = Symbol('x')
>>> polar_lift(4)
4*exp_polar(0)
>>> polar_lift(-4)
4*exp_polar(I*pi)
>>> polar_lift(-I)
exp_polar(-I*pi/2)
>>> polar_lift(I + 2)
polar_lift(2 + I)
>>> polar_lift(4*x)
4*polar_lift(x)
>>> polar_lift(4*p)
4*p
Parameters
==========
arg : Expr
Real or complex expression.
See Also
========
sympy.functions.elementary.exponential.exp_polar
periodic_argument
"""
is_polar = True
is_comparable = False # Cannot be evalf'd.
@classmethod
def eval(cls, arg):
from sympy.functions.elementary.complexes import arg as argument
if arg.is_number:
ar = argument(arg)
# In general we want to affirm that something is known,
# e.g. `not ar.has(argument) and not ar.has(atan)`
# but for now we will just be more restrictive and
# see that it has evaluated to one of the known values.
if ar in (0, pi/2, -pi/2, pi):
return exp_polar(I*ar)*abs(arg)
if arg.is_Mul:
args = arg.args
else:
args = [arg]
included = []
excluded = []
positive = []
for arg in args:
if arg.is_polar:
included += [arg]
elif arg.is_positive:
positive += [arg]
else:
excluded += [arg]
if len(excluded) < len(args):
if excluded:
return Mul(*(included + positive))*polar_lift(Mul(*excluded))
elif included:
return Mul(*(included + positive))
else:
return Mul(*positive)*exp_polar(0)
def _eval_evalf(self, prec):
""" Careful! any evalf of polar numbers is flaky """
return self.args[0]._eval_evalf(prec)
def _eval_Abs(self):
return Abs(self.args[0], evaluate=True)
class periodic_argument(Function):
"""
Represent the argument on a quotient of the Riemann surface of the
logarithm. That is, given a period $P$, always return a value in
(-P/2, P/2], by using exp(P*I) == 1.
Examples
========
>>> from sympy import exp_polar, periodic_argument
>>> from sympy import I, pi
>>> periodic_argument(exp_polar(10*I*pi), 2*pi)
0
>>> periodic_argument(exp_polar(5*I*pi), 4*pi)
pi
>>> from sympy import exp_polar, periodic_argument
>>> from sympy import I, pi
>>> periodic_argument(exp_polar(5*I*pi), 2*pi)
pi
>>> periodic_argument(exp_polar(5*I*pi), 3*pi)
-pi
>>> periodic_argument(exp_polar(5*I*pi), pi)
0
Parameters
==========
ar : Expr
A polar number.
period : ExprT
The period $P$.
See Also
========
sympy.functions.elementary.exponential.exp_polar
polar_lift : Lift argument to the Riemann surface of the logarithm
principal_branch
"""
@classmethod
def _getunbranched(cls, ar):
if ar.is_Mul:
args = ar.args
else:
args = [ar]
unbranched = 0
for a in args:
if not a.is_polar:
unbranched += arg(a)
elif isinstance(a, exp_polar):
unbranched += a.exp.as_real_imag()[1]
elif a.is_Pow:
re, im = a.exp.as_real_imag()
unbranched += re*unbranched_argument(
a.base) + im*log(abs(a.base))
elif isinstance(a, polar_lift):
unbranched += arg(a.args[0])
else:
return None
return unbranched
@classmethod
def eval(cls, ar, period):
# Our strategy is to evaluate the argument on the Riemann surface of the
# logarithm, and then reduce.
# NOTE evidently this means it is a rather bad idea to use this with
# period != 2*pi and non-polar numbers.
if not period.is_extended_positive:
return None
if period == oo and isinstance(ar, principal_branch):
return periodic_argument(*ar.args)
if isinstance(ar, polar_lift) and period >= 2*pi:
return periodic_argument(ar.args[0], period)
if ar.is_Mul:
newargs = [x for x in ar.args if not x.is_positive]
if len(newargs) != len(ar.args):
return periodic_argument(Mul(*newargs), period)
unbranched = cls._getunbranched(ar)
if unbranched is None:
return None
if unbranched.has(periodic_argument, atan2, atan):
return None
if period == oo:
return unbranched
if period != oo:
n = ceiling(unbranched/period - S.Half)*period
if not n.has(ceiling):
return unbranched - n
def _eval_evalf(self, prec):
z, period = self.args
if period == oo:
unbranched = periodic_argument._getunbranched(z)
if unbranched is None:
return self
return unbranched._eval_evalf(prec)
ub = periodic_argument(z, oo)._eval_evalf(prec)
return (ub - ceiling(ub/period - S.Half)*period)._eval_evalf(prec)
def unbranched_argument(arg):
'''
Returns periodic argument of arg with period as infinity.
Examples
========
>>> from sympy import exp_polar, unbranched_argument
>>> from sympy import I, pi
>>> unbranched_argument(exp_polar(15*I*pi))
15*pi
>>> unbranched_argument(exp_polar(7*I*pi))
7*pi
See also
========
periodic_argument
'''
return periodic_argument(arg, oo)
class principal_branch(Function):
"""
Represent a polar number reduced to its principal branch on a quotient
of the Riemann surface of the logarithm.
Explanation
===========
This is a function of two arguments. The first argument is a polar
number `z`, and the second one a positive real number or infinity, `p`.
The result is "z mod exp_polar(I*p)".
Examples
========
>>> from sympy import exp_polar, principal_branch, oo, I, pi
>>> from sympy.abc import z
>>> principal_branch(z, oo)
z
>>> principal_branch(exp_polar(2*pi*I)*3, 2*pi)
3*exp_polar(0)
>>> principal_branch(exp_polar(2*pi*I)*3*z, 2*pi)
3*principal_branch(z, 2*pi)
Parameters
==========
x : Expr
A polar number.
period : Expr
Positive real number or infinity.
See Also
========
sympy.functions.elementary.exponential.exp_polar
polar_lift : Lift argument to the Riemann surface of the logarithm
periodic_argument
"""
is_polar = True
is_comparable = False # cannot always be evalf'd
@classmethod
def eval(self, x, period):
from sympy import oo, exp_polar, I, Mul, polar_lift, Symbol
if isinstance(x, polar_lift):
return principal_branch(x.args[0], period)
if period == oo:
return x
ub = periodic_argument(x, oo)
barg = periodic_argument(x, period)
if ub != barg and not ub.has(periodic_argument) \
and not barg.has(periodic_argument):
pl = polar_lift(x)
def mr(expr):
if not isinstance(expr, Symbol):
return polar_lift(expr)
return expr
pl = pl.replace(polar_lift, mr)
# Recompute unbranched argument
ub = periodic_argument(pl, oo)
if not pl.has(polar_lift):
if ub != barg:
res = exp_polar(I*(barg - ub))*pl
else:
res = pl
if not res.is_polar and not res.has(exp_polar):
res *= exp_polar(0)
return res
if not x.free_symbols:
c, m = x, ()
else:
c, m = x.as_coeff_mul(*x.free_symbols)
others = []
for y in m:
if y.is_positive:
c *= y
else:
others += [y]
m = tuple(others)
arg = periodic_argument(c, period)
if arg.has(periodic_argument):
return None
if arg.is_number and (unbranched_argument(c) != arg or
(arg == 0 and m != () and c != 1)):
if arg == 0:
return abs(c)*principal_branch(Mul(*m), period)
return principal_branch(exp_polar(I*arg)*Mul(*m), period)*abs(c)
if arg.is_number and ((abs(arg) < period/2) == True or arg == period/2) \
and m == ():
return exp_polar(arg*I)*abs(c)
def _eval_evalf(self, prec):
from sympy import exp, pi, I
z, period = self.args
p = periodic_argument(z, period)._eval_evalf(prec)
if abs(p) > pi or p == -pi:
return self # Cannot evalf for this argument.
return (abs(z)*exp(I*p))._eval_evalf(prec)
def _polarify(eq, lift, pause=False):
from sympy import Integral
if eq.is_polar:
return eq
if eq.is_number and not pause:
return polar_lift(eq)
if isinstance(eq, Symbol) and not pause and lift:
return polar_lift(eq)
elif eq.is_Atom:
return eq
elif eq.is_Add:
r = eq.func(*[_polarify(arg, lift, pause=True) for arg in eq.args])
if lift:
return polar_lift(r)
return r
elif eq.is_Pow and eq.base == S.Exp1:
return eq.func(S.Exp1, _polarify(eq.exp, lift, pause=False))
elif eq.is_Function:
return eq.func(*[_polarify(arg, lift, pause=False) for arg in eq.args])
elif isinstance(eq, Integral):
# Don't lift the integration variable
func = _polarify(eq.function, lift, pause=pause)
limits = []
for limit in eq.args[1:]:
var = _polarify(limit[0], lift=False, pause=pause)
rest = _polarify(limit[1:], lift=lift, pause=pause)
limits.append((var,) + rest)
return Integral(*((func,) + tuple(limits)))
else:
return eq.func(*[_polarify(arg, lift, pause=pause)
if isinstance(arg, Expr) else arg for arg in eq.args])
def polarify(eq, subs=True, lift=False):
"""
Turn all numbers in eq into their polar equivalents (under the standard
choice of argument).
Note that no attempt is made to guess a formal convention of adding
polar numbers, expressions like 1 + x will generally not be altered.
Note also that this function does not promote exp(x) to exp_polar(x).
If ``subs`` is True, all symbols which are not already polar will be
substituted for polar dummies; in this case the function behaves much
like posify.
If ``lift`` is True, both addition statements and non-polar symbols are
changed to their polar_lift()ed versions.
Note that lift=True implies subs=False.
Examples
========
>>> from sympy import polarify, sin, I
>>> from sympy.abc import x, y
>>> expr = (-x)**y
>>> expr.expand()
(-x)**y
>>> polarify(expr)
((_x*exp_polar(I*pi))**_y, {_x: x, _y: y})
>>> polarify(expr)[0].expand()
_x**_y*exp_polar(_y*I*pi)
>>> polarify(x, lift=True)
polar_lift(x)
>>> polarify(x*(1+y), lift=True)
polar_lift(x)*polar_lift(y + 1)
Adds are treated carefully:
>>> polarify(1 + sin((1 + I)*x))
(sin(_x*polar_lift(1 + I)) + 1, {_x: x})
"""
if lift:
subs = False
eq = _polarify(sympify(eq), lift)
if not subs:
return eq
reps = {s: Dummy(s.name, polar=True) for s in eq.free_symbols}
eq = eq.subs(reps)
return eq, {r: s for s, r in reps.items()}
def _unpolarify(eq, exponents_only, pause=False):
if not isinstance(eq, Basic) or eq.is_Atom:
return eq
if not pause:
if isinstance(eq, exp_polar):
return exp(_unpolarify(eq.exp, exponents_only))
if isinstance(eq, principal_branch) and eq.args[1] == 2*pi:
return _unpolarify(eq.args[0], exponents_only)
if (
eq.is_Add or eq.is_Mul or eq.is_Boolean or
eq.is_Relational and (
eq.rel_op in ('==', '!=') and 0 in eq.args or
eq.rel_op not in ('==', '!='))
):
return eq.func(*[_unpolarify(x, exponents_only) for x in eq.args])
if isinstance(eq, polar_lift):
return _unpolarify(eq.args[0], exponents_only)
if eq.is_Pow:
expo = _unpolarify(eq.exp, exponents_only)
base = _unpolarify(eq.base, exponents_only,
not (expo.is_integer and not pause))
return base**expo
if eq.is_Function and getattr(eq.func, 'unbranched', False):
return eq.func(*[_unpolarify(x, exponents_only, exponents_only)
for x in eq.args])
return eq.func(*[_unpolarify(x, exponents_only, True) for x in eq.args])
def unpolarify(eq, subs={}, exponents_only=False):
"""
If p denotes the projection from the Riemann surface of the logarithm to
the complex line, return a simplified version eq' of `eq` such that
p(eq') == p(eq).
Also apply the substitution subs in the end. (This is a convenience, since
``unpolarify``, in a certain sense, undoes polarify.)
Examples
========
>>> from sympy import unpolarify, polar_lift, sin, I
>>> unpolarify(polar_lift(I + 2))
2 + I
>>> unpolarify(sin(polar_lift(I + 7)))
sin(7 + I)
"""
if isinstance(eq, bool):
return eq
eq = sympify(eq)
if subs != {}:
return unpolarify(eq.subs(subs))
changed = True
pause = False
if exponents_only:
pause = True
while changed:
changed = False
res = _unpolarify(eq, exponents_only, pause)
if res != eq:
changed = True
eq = res
if isinstance(res, bool):
return res
# Finally, replacing Exp(0) by 1 is always correct.
# So is polar_lift(0) -> 0.
return res.subs({exp_polar(0): 1, polar_lift(0): 0})
|
6eb224a03dbc666c3ac999c8fdc7d7d50c72f5aacdbe09e77f45bc7ba8665931 | """Hypergeometric and Meijer G-functions"""
from functools import reduce
from sympy.core import S, I, pi, oo, zoo, ilcm, Mod
from sympy.core.function import Function, Derivative, ArgumentIndexError
from sympy.core.containers import Tuple
from sympy.core.mul import Mul
from sympy.core.symbol import Dummy
from sympy.functions import (sqrt, exp, log, sin, cos, asin, atan,
sinh, cosh, asinh, acosh, atanh, acoth, Abs, re)
from sympy.utilities.iterables import default_sort_key
class TupleArg(Tuple):
def limit(self, x, xlim, dir='+'):
""" Compute limit x->xlim.
"""
from sympy.series.limits import limit
return TupleArg(*[limit(f, x, xlim, dir) for f in self.args])
# TODO should __new__ accept **options?
# TODO should constructors should check if parameters are sensible?
def _prep_tuple(v):
"""
Turn an iterable argument *v* into a tuple and unpolarify, since both
hypergeometric and meijer g-functions are unbranched in their parameters.
Examples
========
>>> from sympy.functions.special.hyper import _prep_tuple
>>> _prep_tuple([1, 2, 3])
(1, 2, 3)
>>> _prep_tuple((4, 5))
(4, 5)
>>> _prep_tuple((7, 8, 9))
(7, 8, 9)
"""
from sympy import unpolarify
return TupleArg(*[unpolarify(x) for x in v])
class TupleParametersBase(Function):
""" Base class that takes care of differentiation, when some of
the arguments are actually tuples. """
# This is not deduced automatically since there are Tuples as arguments.
is_commutative = True
def _eval_derivative(self, s):
try:
res = 0
if self.args[0].has(s) or self.args[1].has(s):
for i, p in enumerate(self._diffargs):
m = self._diffargs[i].diff(s)
if m != 0:
res += self.fdiff((1, i))*m
return res + self.fdiff(3)*self.args[2].diff(s)
except (ArgumentIndexError, NotImplementedError):
return Derivative(self, s)
class hyper(TupleParametersBase):
r"""
The generalized hypergeometric function is defined by a series where
the ratios of successive terms are a rational function of the summation
index. When convergent, it is continued analytically to the largest
possible domain.
Explanation
===========
The hypergeometric function depends on two vectors of parameters, called
the numerator parameters $a_p$, and the denominator parameters
$b_q$. It also has an argument $z$. The series definition is
.. math ::
{}_pF_q\left(\begin{matrix} a_1, \cdots, a_p \\ b_1, \cdots, b_q \end{matrix}
\middle| z \right)
= \sum_{n=0}^\infty \frac{(a_1)_n \cdots (a_p)_n}{(b_1)_n \cdots (b_q)_n}
\frac{z^n}{n!},
where $(a)_n = (a)(a+1)\cdots(a+n-1)$ denotes the rising factorial.
If one of the $b_q$ is a non-positive integer then the series is
undefined unless one of the $a_p$ is a larger (i.e., smaller in
magnitude) non-positive integer. If none of the $b_q$ is a
non-positive integer and one of the $a_p$ is a non-positive
integer, then the series reduces to a polynomial. To simplify the
following discussion, we assume that none of the $a_p$ or
$b_q$ is a non-positive integer. For more details, see the
references.
The series converges for all $z$ if $p \le q$, and thus
defines an entire single-valued function in this case. If $p =
q+1$ the series converges for $|z| < 1$, and can be continued
analytically into a half-plane. If $p > q+1$ the series is
divergent for all $z$.
Please note the hypergeometric function constructor currently does *not*
check if the parameters actually yield a well-defined function.
Examples
========
The parameters $a_p$ and $b_q$ can be passed as arbitrary
iterables, for example:
>>> from sympy.functions import hyper
>>> from sympy.abc import x, n, a
>>> hyper((1, 2, 3), [3, 4], x)
hyper((1, 2, 3), (3, 4), x)
There is also pretty printing (it looks better using Unicode):
>>> from sympy import pprint
>>> pprint(hyper((1, 2, 3), [3, 4], x), use_unicode=False)
_
|_ /1, 2, 3 | \
| | | x|
3 2 \ 3, 4 | /
The parameters must always be iterables, even if they are vectors of
length one or zero:
>>> hyper((1, ), [], x)
hyper((1,), (), x)
But of course they may be variables (but if they depend on $x$ then you
should not expect much implemented functionality):
>>> hyper((n, a), (n**2,), x)
hyper((n, a), (n**2,), x)
The hypergeometric function generalizes many named special functions.
The function ``hyperexpand()`` tries to express a hypergeometric function
using named special functions. For example:
>>> from sympy import hyperexpand
>>> hyperexpand(hyper([], [], x))
exp(x)
You can also use ``expand_func()``:
>>> from sympy import expand_func
>>> expand_func(x*hyper([1, 1], [2], -x))
log(x + 1)
More examples:
>>> from sympy import S
>>> hyperexpand(hyper([], [S(1)/2], -x**2/4))
cos(x)
>>> hyperexpand(x*hyper([S(1)/2, S(1)/2], [S(3)/2], x**2))
asin(x)
We can also sometimes ``hyperexpand()`` parametric functions:
>>> from sympy.abc import a
>>> hyperexpand(hyper([-a], [], x))
(1 - x)**a
See Also
========
sympy.simplify.hyperexpand
gamma
meijerg
References
==========
.. [1] Luke, Y. L. (1969), The Special Functions and Their Approximations,
Volume 1
.. [2] https://en.wikipedia.org/wiki/Generalized_hypergeometric_function
"""
def __new__(cls, ap, bq, z, **kwargs):
# TODO should we check convergence conditions?
return Function.__new__(cls, _prep_tuple(ap), _prep_tuple(bq), z, **kwargs)
@classmethod
def eval(cls, ap, bq, z):
from sympy import unpolarify
if len(ap) <= len(bq) or (len(ap) == len(bq) + 1 and (Abs(z) <= 1) == True):
nz = unpolarify(z)
if z != nz:
return hyper(ap, bq, nz)
def fdiff(self, argindex=3):
if argindex != 3:
raise ArgumentIndexError(self, argindex)
nap = Tuple(*[a + 1 for a in self.ap])
nbq = Tuple(*[b + 1 for b in self.bq])
fac = Mul(*self.ap)/Mul(*self.bq)
return fac*hyper(nap, nbq, self.argument)
def _eval_expand_func(self, **hints):
from sympy import gamma, hyperexpand
if len(self.ap) == 2 and len(self.bq) == 1 and self.argument == 1:
a, b = self.ap
c = self.bq[0]
return gamma(c)*gamma(c - a - b)/gamma(c - a)/gamma(c - b)
return hyperexpand(self)
def _eval_rewrite_as_Sum(self, ap, bq, z, **kwargs):
from sympy.functions import factorial, RisingFactorial, Piecewise
from sympy import Sum
n = Dummy("n", integer=True)
rfap = Tuple(*[RisingFactorial(a, n) for a in ap])
rfbq = Tuple(*[RisingFactorial(b, n) for b in bq])
coeff = Mul(*rfap) / Mul(*rfbq)
return Piecewise((Sum(coeff * z**n / factorial(n), (n, 0, oo)),
self.convergence_statement), (self, True))
def _eval_as_leading_term(self, x, logx=None, cdir=0):
arg = self.args[2]
x0 = arg.subs(x, 0)
if x0 is S.NaN:
x0 = arg.limit(x, 0, dir='-' if re(cdir).is_negative else '+')
if x0 is S.Zero:
return S.One
return super()._eval_as_leading_term(x, logx=logx, cdir=cdir)
def _eval_nseries(self, x, n, logx, cdir=0):
from sympy.functions import factorial, RisingFactorial
from sympy import Order, Add
arg = self.args[2]
x0 = arg.limit(x, 0)
ap = self.args[0]
bq = self.args[1]
if x0 != 0:
return super()._eval_nseries(x, n, logx)
terms = []
for i in range(n):
num = 1
den = 1
for a in ap:
num *= RisingFactorial(a, i)
for b in bq:
den *= RisingFactorial(b, i)
terms.append(((num/den) * (arg**i)) / factorial(i))
return (Add(*terms) + Order(x**n,x))
@property
def argument(self):
""" Argument of the hypergeometric function. """
return self.args[2]
@property
def ap(self):
""" Numerator parameters of the hypergeometric function. """
return Tuple(*self.args[0])
@property
def bq(self):
""" Denominator parameters of the hypergeometric function. """
return Tuple(*self.args[1])
@property
def _diffargs(self):
return self.ap + self.bq
@property
def eta(self):
""" A quantity related to the convergence of the series. """
return sum(self.ap) - sum(self.bq)
@property
def radius_of_convergence(self):
"""
Compute the radius of convergence of the defining series.
Explanation
===========
Note that even if this is not ``oo``, the function may still be
evaluated outside of the radius of convergence by analytic
continuation. But if this is zero, then the function is not actually
defined anywhere else.
Examples
========
>>> from sympy.functions import hyper
>>> from sympy.abc import z
>>> hyper((1, 2), [3], z).radius_of_convergence
1
>>> hyper((1, 2, 3), [4], z).radius_of_convergence
0
>>> hyper((1, 2), (3, 4), z).radius_of_convergence
oo
"""
if any(a.is_integer and (a <= 0) == True for a in self.ap + self.bq):
aints = [a for a in self.ap if a.is_Integer and (a <= 0) == True]
bints = [a for a in self.bq if a.is_Integer and (a <= 0) == True]
if len(aints) < len(bints):
return S.Zero
popped = False
for b in bints:
cancelled = False
while aints:
a = aints.pop()
if a >= b:
cancelled = True
break
popped = True
if not cancelled:
return S.Zero
if aints or popped:
# There are still non-positive numerator parameters.
# This is a polynomial.
return oo
if len(self.ap) == len(self.bq) + 1:
return S.One
elif len(self.ap) <= len(self.bq):
return oo
else:
return S.Zero
@property
def convergence_statement(self):
""" Return a condition on z under which the series converges. """
from sympy import And, Or, re, Ne, oo
R = self.radius_of_convergence
if R == 0:
return False
if R == oo:
return True
# The special functions and their approximations, page 44
e = self.eta
z = self.argument
c1 = And(re(e) < 0, abs(z) <= 1)
c2 = And(0 <= re(e), re(e) < 1, abs(z) <= 1, Ne(z, 1))
c3 = And(re(e) >= 1, abs(z) < 1)
return Or(c1, c2, c3)
def _eval_simplify(self, **kwargs):
from sympy.simplify.hyperexpand import hyperexpand
return hyperexpand(self)
def _sage_(self):
import sage.all as sage
ap = [arg._sage_() for arg in self.args[0]]
bq = [arg._sage_() for arg in self.args[1]]
return sage.hypergeometric(ap, bq, self.argument._sage_())
class meijerg(TupleParametersBase):
r"""
The Meijer G-function is defined by a Mellin-Barnes type integral that
resembles an inverse Mellin transform. It generalizes the hypergeometric
functions.
Explanation
===========
The Meijer G-function depends on four sets of parameters. There are
"*numerator parameters*"
$a_1, \ldots, a_n$ and $a_{n+1}, \ldots, a_p$, and there are
"*denominator parameters*"
$b_1, \ldots, b_m$ and $b_{m+1}, \ldots, b_q$.
Confusingly, it is traditionally denoted as follows (note the position
of $m$, $n$, $p$, $q$, and how they relate to the lengths of the four
parameter vectors):
.. math ::
G_{p,q}^{m,n} \left(\begin{matrix}a_1, \cdots, a_n & a_{n+1}, \cdots, a_p \\
b_1, \cdots, b_m & b_{m+1}, \cdots, b_q
\end{matrix} \middle| z \right).
However, in SymPy the four parameter vectors are always available
separately (see examples), so that there is no need to keep track of the
decorating sub- and super-scripts on the G symbol.
The G function is defined as the following integral:
.. math ::
\frac{1}{2 \pi i} \int_L \frac{\prod_{j=1}^m \Gamma(b_j - s)
\prod_{j=1}^n \Gamma(1 - a_j + s)}{\prod_{j=m+1}^q \Gamma(1- b_j +s)
\prod_{j=n+1}^p \Gamma(a_j - s)} z^s \mathrm{d}s,
where $\Gamma(z)$ is the gamma function. There are three possible
contours which we will not describe in detail here (see the references).
If the integral converges along more than one of them, the definitions
agree. The contours all separate the poles of $\Gamma(1-a_j+s)$
from the poles of $\Gamma(b_k-s)$, so in particular the G function
is undefined if $a_j - b_k \in \mathbb{Z}_{>0}$ for some
$j \le n$ and $k \le m$.
The conditions under which one of the contours yields a convergent integral
are complicated and we do not state them here, see the references.
Please note currently the Meijer G-function constructor does *not* check any
convergence conditions.
Examples
========
You can pass the parameters either as four separate vectors:
>>> from sympy.functions import meijerg
>>> from sympy.abc import x, a
>>> from sympy.core.containers import Tuple
>>> from sympy import pprint
>>> pprint(meijerg((1, 2), (a, 4), (5,), [], x), use_unicode=False)
__1, 2 /1, 2 a, 4 | \
/__ | | x|
\_|4, 1 \ 5 | /
Or as two nested vectors:
>>> pprint(meijerg([(1, 2), (3, 4)], ([5], Tuple()), x), use_unicode=False)
__1, 2 /1, 2 3, 4 | \
/__ | | x|
\_|4, 1 \ 5 | /
As with the hypergeometric function, the parameters may be passed as
arbitrary iterables. Vectors of length zero and one also have to be
passed as iterables. The parameters need not be constants, but if they
depend on the argument then not much implemented functionality should be
expected.
All the subvectors of parameters are available:
>>> from sympy import pprint
>>> g = meijerg([1], [2], [3], [4], x)
>>> pprint(g, use_unicode=False)
__1, 1 /1 2 | \
/__ | | x|
\_|2, 2 \3 4 | /
>>> g.an
(1,)
>>> g.ap
(1, 2)
>>> g.aother
(2,)
>>> g.bm
(3,)
>>> g.bq
(3, 4)
>>> g.bother
(4,)
The Meijer G-function generalizes the hypergeometric functions.
In some cases it can be expressed in terms of hypergeometric functions,
using Slater's theorem. For example:
>>> from sympy import hyperexpand
>>> from sympy.abc import a, b, c
>>> hyperexpand(meijerg([a], [], [c], [b], x), allow_hyper=True)
x**c*gamma(-a + c + 1)*hyper((-a + c + 1,),
(-b + c + 1,), -x)/gamma(-b + c + 1)
Thus the Meijer G-function also subsumes many named functions as special
cases. You can use ``expand_func()`` or ``hyperexpand()`` to (try to)
rewrite a Meijer G-function in terms of named special functions. For
example:
>>> from sympy import expand_func, S
>>> expand_func(meijerg([[],[]], [[0],[]], -x))
exp(x)
>>> hyperexpand(meijerg([[],[]], [[S(1)/2],[0]], (x/2)**2))
sin(x)/sqrt(pi)
See Also
========
hyper
sympy.simplify.hyperexpand
References
==========
.. [1] Luke, Y. L. (1969), The Special Functions and Their Approximations,
Volume 1
.. [2] https://en.wikipedia.org/wiki/Meijer_G-function
"""
def __new__(cls, *args, **kwargs):
if len(args) == 5:
args = [(args[0], args[1]), (args[2], args[3]), args[4]]
if len(args) != 3:
raise TypeError("args must be either as, as', bs, bs', z or "
"as, bs, z")
def tr(p):
if len(p) != 2:
raise TypeError("wrong argument")
return TupleArg(_prep_tuple(p[0]), _prep_tuple(p[1]))
arg0, arg1 = tr(args[0]), tr(args[1])
if Tuple(arg0, arg1).has(oo, zoo, -oo):
raise ValueError("G-function parameters must be finite")
if any((a - b).is_Integer and a - b > 0
for a in arg0[0] for b in arg1[0]):
raise ValueError("no parameter a1, ..., an may differ from "
"any b1, ..., bm by a positive integer")
# TODO should we check convergence conditions?
return Function.__new__(cls, arg0, arg1, args[2], **kwargs)
def fdiff(self, argindex=3):
if argindex != 3:
return self._diff_wrt_parameter(argindex[1])
if len(self.an) >= 1:
a = list(self.an)
a[0] -= 1
G = meijerg(a, self.aother, self.bm, self.bother, self.argument)
return 1/self.argument * ((self.an[0] - 1)*self + G)
elif len(self.bm) >= 1:
b = list(self.bm)
b[0] += 1
G = meijerg(self.an, self.aother, b, self.bother, self.argument)
return 1/self.argument * (self.bm[0]*self - G)
else:
return S.Zero
def _diff_wrt_parameter(self, idx):
# Differentiation wrt a parameter can only be done in very special
# cases. In particular, if we want to differentiate with respect to
# `a`, all other gamma factors have to reduce to rational functions.
#
# Let MT denote mellin transform. Suppose T(-s) is the gamma factor
# appearing in the definition of G. Then
#
# MT(log(z)G(z)) = d/ds T(s) = d/da T(s) + ...
#
# Thus d/da G(z) = log(z)G(z) - ...
# The ... can be evaluated as a G function under the above conditions,
# the formula being most easily derived by using
#
# d Gamma(s + n) Gamma(s + n) / 1 1 1 \
# -- ------------ = ------------ | - + ---- + ... + --------- |
# ds Gamma(s) Gamma(s) \ s s + 1 s + n - 1 /
#
# which follows from the difference equation of the digamma function.
# (There is a similar equation for -n instead of +n).
# We first figure out how to pair the parameters.
an = list(self.an)
ap = list(self.aother)
bm = list(self.bm)
bq = list(self.bother)
if idx < len(an):
an.pop(idx)
else:
idx -= len(an)
if idx < len(ap):
ap.pop(idx)
else:
idx -= len(ap)
if idx < len(bm):
bm.pop(idx)
else:
bq.pop(idx - len(bm))
pairs1 = []
pairs2 = []
for l1, l2, pairs in [(an, bq, pairs1), (ap, bm, pairs2)]:
while l1:
x = l1.pop()
found = None
for i, y in enumerate(l2):
if not Mod((x - y).simplify(), 1):
found = i
break
if found is None:
raise NotImplementedError('Derivative not expressible '
'as G-function?')
y = l2[i]
l2.pop(i)
pairs.append((x, y))
# Now build the result.
res = log(self.argument)*self
for a, b in pairs1:
sign = 1
n = a - b
base = b
if n < 0:
sign = -1
n = b - a
base = a
for k in range(n):
res -= sign*meijerg(self.an + (base + k + 1,), self.aother,
self.bm, self.bother + (base + k + 0,),
self.argument)
for a, b in pairs2:
sign = 1
n = b - a
base = a
if n < 0:
sign = -1
n = a - b
base = b
for k in range(n):
res -= sign*meijerg(self.an, self.aother + (base + k + 1,),
self.bm + (base + k + 0,), self.bother,
self.argument)
return res
def get_period(self):
"""
Return a number $P$ such that $G(x*exp(I*P)) == G(x)$.
Examples
========
>>> from sympy.functions.special.hyper import meijerg
>>> from sympy.abc import z
>>> from sympy import pi, S
>>> meijerg([1], [], [], [], z).get_period()
2*pi
>>> meijerg([pi], [], [], [], z).get_period()
oo
>>> meijerg([1, 2], [], [], [], z).get_period()
oo
>>> meijerg([1,1], [2], [1, S(1)/2, S(1)/3], [1], z).get_period()
12*pi
"""
# This follows from slater's theorem.
def compute(l):
# first check that no two differ by an integer
for i, b in enumerate(l):
if not b.is_Rational:
return oo
for j in range(i + 1, len(l)):
if not Mod((b - l[j]).simplify(), 1):
return oo
return reduce(ilcm, (x.q for x in l), 1)
beta = compute(self.bm)
alpha = compute(self.an)
p, q = len(self.ap), len(self.bq)
if p == q:
if beta == oo or alpha == oo:
return oo
return 2*pi*ilcm(alpha, beta)
elif p < q:
return 2*pi*beta
else:
return 2*pi*alpha
def _eval_expand_func(self, **hints):
from sympy import hyperexpand
return hyperexpand(self)
def _eval_evalf(self, prec):
# The default code is insufficient for polar arguments.
# mpmath provides an optional argument "r", which evaluates
# G(z**(1/r)). I am not sure what its intended use is, but we hijack it
# here in the following way: to evaluate at a number z of |argument|
# less than (say) n*pi, we put r=1/n, compute z' = root(z, n)
# (carefully so as not to loose the branch information), and evaluate
# G(z'**(1/r)) = G(z'**n) = G(z).
from sympy.functions import exp_polar, ceiling
from sympy import Expr
import mpmath
znum = self.argument._eval_evalf(prec)
if znum.has(exp_polar):
znum, branch = znum.as_coeff_mul(exp_polar)
if len(branch) != 1:
return
branch = branch[0].args[0]/I
else:
branch = S.Zero
n = ceiling(abs(branch/S.Pi)) + 1
znum = znum**(S.One/n)*exp(I*branch / n)
# Convert all args to mpf or mpc
try:
[z, r, ap, bq] = [arg._to_mpmath(prec)
for arg in [znum, 1/n, self.args[0], self.args[1]]]
except ValueError:
return
with mpmath.workprec(prec):
v = mpmath.meijerg(ap, bq, z, r)
return Expr._from_mpmath(v, prec)
def _eval_as_leading_term(self, x, logx=None, cdir=0):
from sympy import hyperexpand
return hyperexpand(self).as_leading_term(x, logx=logx, cdir=cdir)
def integrand(self, s):
""" Get the defining integrand D(s). """
from sympy import gamma
return self.argument**s \
* Mul(*(gamma(b - s) for b in self.bm)) \
* Mul(*(gamma(1 - a + s) for a in self.an)) \
/ Mul(*(gamma(1 - b + s) for b in self.bother)) \
/ Mul(*(gamma(a - s) for a in self.aother))
@property
def argument(self):
""" Argument of the Meijer G-function. """
return self.args[2]
@property
def an(self):
""" First set of numerator parameters. """
return Tuple(*self.args[0][0])
@property
def ap(self):
""" Combined numerator parameters. """
return Tuple(*(self.args[0][0] + self.args[0][1]))
@property
def aother(self):
""" Second set of numerator parameters. """
return Tuple(*self.args[0][1])
@property
def bm(self):
""" First set of denominator parameters. """
return Tuple(*self.args[1][0])
@property
def bq(self):
""" Combined denominator parameters. """
return Tuple(*(self.args[1][0] + self.args[1][1]))
@property
def bother(self):
""" Second set of denominator parameters. """
return Tuple(*self.args[1][1])
@property
def _diffargs(self):
return self.ap + self.bq
@property
def nu(self):
""" A quantity related to the convergence region of the integral,
c.f. references. """
return sum(self.bq) - sum(self.ap)
@property
def delta(self):
""" A quantity related to the convergence region of the integral,
c.f. references. """
return len(self.bm) + len(self.an) - S(len(self.ap) + len(self.bq))/2
@property
def is_number(self):
""" Returns true if expression has numeric data only. """
return not self.free_symbols
class HyperRep(Function):
"""
A base class for "hyper representation functions".
This is used exclusively in ``hyperexpand()``, but fits more logically here.
pFq is branched at 1 if p == q+1. For use with slater-expansion, we want
define an "analytic continuation" to all polar numbers, which is
continuous on circles and on the ray t*exp_polar(I*pi). Moreover, we want
a "nice" expression for the various cases.
This base class contains the core logic, concrete derived classes only
supply the actual functions.
"""
@classmethod
def eval(cls, *args):
from sympy import unpolarify
newargs = tuple(map(unpolarify, args[:-1])) + args[-1:]
if args != newargs:
return cls(*newargs)
@classmethod
def _expr_small(cls, x):
""" An expression for F(x) which holds for |x| < 1. """
raise NotImplementedError
@classmethod
def _expr_small_minus(cls, x):
""" An expression for F(-x) which holds for |x| < 1. """
raise NotImplementedError
@classmethod
def _expr_big(cls, x, n):
""" An expression for F(exp_polar(2*I*pi*n)*x), |x| > 1. """
raise NotImplementedError
@classmethod
def _expr_big_minus(cls, x, n):
""" An expression for F(exp_polar(2*I*pi*n + pi*I)*x), |x| > 1. """
raise NotImplementedError
def _eval_rewrite_as_nonrep(self, *args, **kwargs):
from sympy import Piecewise
x, n = self.args[-1].extract_branch_factor(allow_half=True)
minus = False
newargs = self.args[:-1] + (x,)
if not n.is_Integer:
minus = True
n -= S.Half
newerargs = newargs + (n,)
if minus:
small = self._expr_small_minus(*newargs)
big = self._expr_big_minus(*newerargs)
else:
small = self._expr_small(*newargs)
big = self._expr_big(*newerargs)
if big == small:
return small
return Piecewise((big, abs(x) > 1), (small, True))
def _eval_rewrite_as_nonrepsmall(self, *args, **kwargs):
x, n = self.args[-1].extract_branch_factor(allow_half=True)
args = self.args[:-1] + (x,)
if not n.is_Integer:
return self._expr_small_minus(*args)
return self._expr_small(*args)
class HyperRep_power1(HyperRep):
""" Return a representative for hyper([-a], [], z) == (1 - z)**a. """
@classmethod
def _expr_small(cls, a, x):
return (1 - x)**a
@classmethod
def _expr_small_minus(cls, a, x):
return (1 + x)**a
@classmethod
def _expr_big(cls, a, x, n):
if a.is_integer:
return cls._expr_small(a, x)
return (x - 1)**a*exp((2*n - 1)*pi*I*a)
@classmethod
def _expr_big_minus(cls, a, x, n):
if a.is_integer:
return cls._expr_small_minus(a, x)
return (1 + x)**a*exp(2*n*pi*I*a)
class HyperRep_power2(HyperRep):
""" Return a representative for hyper([a, a - 1/2], [2*a], z). """
@classmethod
def _expr_small(cls, a, x):
return 2**(2*a - 1)*(1 + sqrt(1 - x))**(1 - 2*a)
@classmethod
def _expr_small_minus(cls, a, x):
return 2**(2*a - 1)*(1 + sqrt(1 + x))**(1 - 2*a)
@classmethod
def _expr_big(cls, a, x, n):
sgn = -1
if n.is_odd:
sgn = 1
n -= 1
return 2**(2*a - 1)*(1 + sgn*I*sqrt(x - 1))**(1 - 2*a) \
*exp(-2*n*pi*I*a)
@classmethod
def _expr_big_minus(cls, a, x, n):
sgn = 1
if n.is_odd:
sgn = -1
return sgn*2**(2*a - 1)*(sqrt(1 + x) + sgn)**(1 - 2*a)*exp(-2*pi*I*a*n)
class HyperRep_log1(HyperRep):
""" Represent -z*hyper([1, 1], [2], z) == log(1 - z). """
@classmethod
def _expr_small(cls, x):
return log(1 - x)
@classmethod
def _expr_small_minus(cls, x):
return log(1 + x)
@classmethod
def _expr_big(cls, x, n):
return log(x - 1) + (2*n - 1)*pi*I
@classmethod
def _expr_big_minus(cls, x, n):
return log(1 + x) + 2*n*pi*I
class HyperRep_atanh(HyperRep):
""" Represent hyper([1/2, 1], [3/2], z) == atanh(sqrt(z))/sqrt(z). """
@classmethod
def _expr_small(cls, x):
return atanh(sqrt(x))/sqrt(x)
def _expr_small_minus(cls, x):
return atan(sqrt(x))/sqrt(x)
def _expr_big(cls, x, n):
if n.is_even:
return (acoth(sqrt(x)) + I*pi/2)/sqrt(x)
else:
return (acoth(sqrt(x)) - I*pi/2)/sqrt(x)
def _expr_big_minus(cls, x, n):
if n.is_even:
return atan(sqrt(x))/sqrt(x)
else:
return (atan(sqrt(x)) - pi)/sqrt(x)
class HyperRep_asin1(HyperRep):
""" Represent hyper([1/2, 1/2], [3/2], z) == asin(sqrt(z))/sqrt(z). """
@classmethod
def _expr_small(cls, z):
return asin(sqrt(z))/sqrt(z)
@classmethod
def _expr_small_minus(cls, z):
return asinh(sqrt(z))/sqrt(z)
@classmethod
def _expr_big(cls, z, n):
return S.NegativeOne**n*((S.Half - n)*pi/sqrt(z) + I*acosh(sqrt(z))/sqrt(z))
@classmethod
def _expr_big_minus(cls, z, n):
return S.NegativeOne**n*(asinh(sqrt(z))/sqrt(z) + n*pi*I/sqrt(z))
class HyperRep_asin2(HyperRep):
""" Represent hyper([1, 1], [3/2], z) == asin(sqrt(z))/sqrt(z)/sqrt(1-z). """
# TODO this can be nicer
@classmethod
def _expr_small(cls, z):
return HyperRep_asin1._expr_small(z) \
/HyperRep_power1._expr_small(S.Half, z)
@classmethod
def _expr_small_minus(cls, z):
return HyperRep_asin1._expr_small_minus(z) \
/HyperRep_power1._expr_small_minus(S.Half, z)
@classmethod
def _expr_big(cls, z, n):
return HyperRep_asin1._expr_big(z, n) \
/HyperRep_power1._expr_big(S.Half, z, n)
@classmethod
def _expr_big_minus(cls, z, n):
return HyperRep_asin1._expr_big_minus(z, n) \
/HyperRep_power1._expr_big_minus(S.Half, z, n)
class HyperRep_sqrts1(HyperRep):
""" Return a representative for hyper([-a, 1/2 - a], [1/2], z). """
@classmethod
def _expr_small(cls, a, z):
return ((1 - sqrt(z))**(2*a) + (1 + sqrt(z))**(2*a))/2
@classmethod
def _expr_small_minus(cls, a, z):
return (1 + z)**a*cos(2*a*atan(sqrt(z)))
@classmethod
def _expr_big(cls, a, z, n):
if n.is_even:
return ((sqrt(z) + 1)**(2*a)*exp(2*pi*I*n*a) +
(sqrt(z) - 1)**(2*a)*exp(2*pi*I*(n - 1)*a))/2
else:
n -= 1
return ((sqrt(z) - 1)**(2*a)*exp(2*pi*I*a*(n + 1)) +
(sqrt(z) + 1)**(2*a)*exp(2*pi*I*a*n))/2
@classmethod
def _expr_big_minus(cls, a, z, n):
if n.is_even:
return (1 + z)**a*exp(2*pi*I*n*a)*cos(2*a*atan(sqrt(z)))
else:
return (1 + z)**a*exp(2*pi*I*n*a)*cos(2*a*atan(sqrt(z)) - 2*pi*a)
class HyperRep_sqrts2(HyperRep):
""" Return a representative for
sqrt(z)/2*[(1-sqrt(z))**2a - (1 + sqrt(z))**2a]
== -2*z/(2*a+1) d/dz hyper([-a - 1/2, -a], [1/2], z)"""
@classmethod
def _expr_small(cls, a, z):
return sqrt(z)*((1 - sqrt(z))**(2*a) - (1 + sqrt(z))**(2*a))/2
@classmethod
def _expr_small_minus(cls, a, z):
return sqrt(z)*(1 + z)**a*sin(2*a*atan(sqrt(z)))
@classmethod
def _expr_big(cls, a, z, n):
if n.is_even:
return sqrt(z)/2*((sqrt(z) - 1)**(2*a)*exp(2*pi*I*a*(n - 1)) -
(sqrt(z) + 1)**(2*a)*exp(2*pi*I*a*n))
else:
n -= 1
return sqrt(z)/2*((sqrt(z) - 1)**(2*a)*exp(2*pi*I*a*(n + 1)) -
(sqrt(z) + 1)**(2*a)*exp(2*pi*I*a*n))
def _expr_big_minus(cls, a, z, n):
if n.is_even:
return (1 + z)**a*exp(2*pi*I*n*a)*sqrt(z)*sin(2*a*atan(sqrt(z)))
else:
return (1 + z)**a*exp(2*pi*I*n*a)*sqrt(z) \
*sin(2*a*atan(sqrt(z)) - 2*pi*a)
class HyperRep_log2(HyperRep):
""" Represent log(1/2 + sqrt(1 - z)/2) == -z/4*hyper([3/2, 1, 1], [2, 2], z) """
@classmethod
def _expr_small(cls, z):
return log(S.Half + sqrt(1 - z)/2)
@classmethod
def _expr_small_minus(cls, z):
return log(S.Half + sqrt(1 + z)/2)
@classmethod
def _expr_big(cls, z, n):
if n.is_even:
return (n - S.Half)*pi*I + log(sqrt(z)/2) + I*asin(1/sqrt(z))
else:
return (n - S.Half)*pi*I + log(sqrt(z)/2) - I*asin(1/sqrt(z))
def _expr_big_minus(cls, z, n):
if n.is_even:
return pi*I*n + log(S.Half + sqrt(1 + z)/2)
else:
return pi*I*n + log(sqrt(1 + z)/2 - S.Half)
class HyperRep_cosasin(HyperRep):
""" Represent hyper([a, -a], [1/2], z) == cos(2*a*asin(sqrt(z))). """
# Note there are many alternative expressions, e.g. as powers of a sum of
# square roots.
@classmethod
def _expr_small(cls, a, z):
return cos(2*a*asin(sqrt(z)))
@classmethod
def _expr_small_minus(cls, a, z):
return cosh(2*a*asinh(sqrt(z)))
@classmethod
def _expr_big(cls, a, z, n):
return cosh(2*a*acosh(sqrt(z)) + a*pi*I*(2*n - 1))
@classmethod
def _expr_big_minus(cls, a, z, n):
return cosh(2*a*asinh(sqrt(z)) + 2*a*pi*I*n)
class HyperRep_sinasin(HyperRep):
""" Represent 2*a*z*hyper([1 - a, 1 + a], [3/2], z)
== sqrt(z)/sqrt(1-z)*sin(2*a*asin(sqrt(z))) """
@classmethod
def _expr_small(cls, a, z):
return sqrt(z)/sqrt(1 - z)*sin(2*a*asin(sqrt(z)))
@classmethod
def _expr_small_minus(cls, a, z):
return -sqrt(z)/sqrt(1 + z)*sinh(2*a*asinh(sqrt(z)))
@classmethod
def _expr_big(cls, a, z, n):
return -1/sqrt(1 - 1/z)*sinh(2*a*acosh(sqrt(z)) + a*pi*I*(2*n - 1))
@classmethod
def _expr_big_minus(cls, a, z, n):
return -1/sqrt(1 + 1/z)*sinh(2*a*asinh(sqrt(z)) + 2*a*pi*I*n)
class appellf1(Function):
r"""
This is the Appell hypergeometric function of two variables as:
.. math ::
F_1(a,b_1,b_2,c,x,y) = \sum_{m=0}^{\infty} \sum_{n=0}^{\infty}
\frac{(a)_{m+n} (b_1)_m (b_2)_n}{(c)_{m+n}}
\frac{x^m y^n}{m! n!}.
Examples
========
>>> from sympy.functions.special.hyper import appellf1
>>> from sympy import symbols
>>> x, y, a, b1, b2, c = symbols('x y a b1 b2 c')
>>> appellf1(2., 1., 6., 4., 5., 6.)
0.0063339426292673
>>> appellf1(12., 12., 6., 4., 0.5, 0.12)
172870711.659936
>>> appellf1(40, 2, 6, 4, 15, 60)
appellf1(40, 2, 6, 4, 15, 60)
>>> appellf1(20., 12., 10., 3., 0.5, 0.12)
15605338197184.4
>>> appellf1(40, 2, 6, 4, x, y)
appellf1(40, 2, 6, 4, x, y)
>>> appellf1(a, b1, b2, c, x, y)
appellf1(a, b1, b2, c, x, y)
References
==========
.. [1] https://en.wikipedia.org/wiki/Appell_series
.. [2] http://functions.wolfram.com/HypergeometricFunctions/AppellF1/
"""
@classmethod
def eval(cls, a, b1, b2, c, x, y):
if default_sort_key(b1) > default_sort_key(b2):
b1, b2 = b2, b1
x, y = y, x
return cls(a, b1, b2, c, x, y)
elif b1 == b2 and default_sort_key(x) > default_sort_key(y):
x, y = y, x
return cls(a, b1, b2, c, x, y)
if x == 0 and y == 0:
return S.One
def fdiff(self, argindex=5):
a, b1, b2, c, x, y = self.args
if argindex == 5:
return (a*b1/c)*appellf1(a + 1, b1 + 1, b2, c + 1, x, y)
elif argindex == 6:
return (a*b2/c)*appellf1(a + 1, b1, b2 + 1, c + 1, x, y)
elif argindex in (1, 2, 3, 4):
return Derivative(self, self.args[argindex-1])
else:
raise ArgumentIndexError(self, argindex)
|
8c4a0d355a03810925ed61873ac6ebce14e0d4b536f310a670d1c5a94120ca40 | from sympy.core import Add, S, sympify, oo, pi, Dummy, expand_func
from sympy.core.compatibility import as_int
from sympy.core.function import Function, ArgumentIndexError
from sympy.core.logic import fuzzy_and, fuzzy_not
from sympy.core.numbers import Rational
from sympy.core.power import Pow
from sympy.functions.special.zeta_functions import zeta
from sympy.functions.special.error_functions import erf, erfc, Ei
from sympy.functions.elementary.complexes import re
from sympy.functions.elementary.exponential import exp, log
from sympy.functions.elementary.integers import ceiling, floor
from sympy.functions.elementary.miscellaneous import sqrt
from sympy.functions.elementary.trigonometric import sin, cos, cot
from sympy.functions.combinatorial.numbers import bernoulli, harmonic
from sympy.functions.combinatorial.factorials import factorial, rf, RisingFactorial
def intlike(n):
try:
as_int(n, strict=False)
return True
except ValueError:
return False
###############################################################################
############################ COMPLETE GAMMA FUNCTION ##########################
###############################################################################
class gamma(Function):
r"""
The gamma function
.. math::
\Gamma(x) := \int^{\infty}_{0} t^{x-1} e^{-t} \mathrm{d}t.
Explanation
===========
The ``gamma`` function implements the function which passes through the
values of the factorial function (i.e., $\Gamma(n) = (n - 1)!$ when n is
an integer). More generally, $\Gamma(z)$ is defined in the whole complex
plane except at the negative integers where there are simple poles.
Examples
========
>>> from sympy import S, I, pi, gamma
>>> from sympy.abc import x
Several special values are known:
>>> gamma(1)
1
>>> gamma(4)
6
>>> gamma(S(3)/2)
sqrt(pi)/2
The ``gamma`` function obeys the mirror symmetry:
>>> from sympy import conjugate
>>> conjugate(gamma(x))
gamma(conjugate(x))
Differentiation with respect to $x$ is supported:
>>> from sympy import diff
>>> diff(gamma(x), x)
gamma(x)*polygamma(0, x)
Series expansion is also supported:
>>> from sympy import series
>>> series(gamma(x), x, 0, 3)
1/x - EulerGamma + x*(EulerGamma**2/2 + pi**2/12) + x**2*(-EulerGamma*pi**2/12 + polygamma(2, 1)/6 - EulerGamma**3/6) + O(x**3)
We can numerically evaluate the ``gamma`` function to arbitrary precision
on the whole complex plane:
>>> gamma(pi).evalf(40)
2.288037795340032417959588909060233922890
>>> gamma(1+I).evalf(20)
0.49801566811835604271 - 0.15494982830181068512*I
See Also
========
lowergamma: Lower incomplete gamma function.
uppergamma: Upper incomplete gamma function.
polygamma: Polygamma function.
loggamma: Log Gamma function.
digamma: Digamma function.
trigamma: Trigamma function.
beta: Euler Beta function.
References
==========
.. [1] https://en.wikipedia.org/wiki/Gamma_function
.. [2] http://dlmf.nist.gov/5
.. [3] http://mathworld.wolfram.com/GammaFunction.html
.. [4] http://functions.wolfram.com/GammaBetaErf/Gamma/
"""
unbranched = True
_singularities = (S.ComplexInfinity,)
def fdiff(self, argindex=1):
if argindex == 1:
return self.func(self.args[0])*polygamma(0, self.args[0])
else:
raise ArgumentIndexError(self, argindex)
@classmethod
def eval(cls, arg):
if arg.is_Number:
if arg is S.NaN:
return S.NaN
elif arg is S.Infinity:
return S.Infinity
elif intlike(arg):
if arg.is_positive:
return factorial(arg - 1)
else:
return S.ComplexInfinity
elif arg.is_Rational:
if arg.q == 2:
n = abs(arg.p) // arg.q
if arg.is_positive:
k, coeff = n, S.One
else:
n = k = n + 1
if n & 1 == 0:
coeff = S.One
else:
coeff = S.NegativeOne
for i in range(3, 2*k, 2):
coeff *= i
if arg.is_positive:
return coeff*sqrt(S.Pi) / 2**n
else:
return 2**n*sqrt(S.Pi) / coeff
def _eval_expand_func(self, **hints):
arg = self.args[0]
if arg.is_Rational:
if abs(arg.p) > arg.q:
x = Dummy('x')
n = arg.p // arg.q
p = arg.p - n*arg.q
return self.func(x + n)._eval_expand_func().subs(x, Rational(p, arg.q))
if arg.is_Add:
coeff, tail = arg.as_coeff_add()
if coeff and coeff.q != 1:
intpart = floor(coeff)
tail = (coeff - intpart,) + tail
coeff = intpart
tail = arg._new_rawargs(*tail, reeval=False)
return self.func(tail)*RisingFactorial(tail, coeff)
return self.func(*self.args)
def _eval_conjugate(self):
return self.func(self.args[0].conjugate())
def _eval_is_real(self):
x = self.args[0]
if x.is_nonpositive and x.is_integer:
return False
if intlike(x) and x <= 0:
return False
if x.is_positive or x.is_noninteger:
return True
def _eval_is_positive(self):
x = self.args[0]
if x.is_positive:
return True
elif x.is_noninteger:
return floor(x).is_even
def _eval_rewrite_as_tractable(self, z, limitvar=None, **kwargs):
return exp(loggamma(z))
def _eval_rewrite_as_factorial(self, z, **kwargs):
return factorial(z - 1)
def _eval_nseries(self, x, n, logx, cdir=0):
x0 = self.args[0].limit(x, 0)
if not (x0.is_Integer and x0 <= 0):
return super()._eval_nseries(x, n, logx)
t = self.args[0] - x0
return (self.func(t + 1)/rf(self.args[0], -x0 + 1))._eval_nseries(x, n, logx)
def _sage_(self):
import sage.all as sage
return sage.gamma(self.args[0]._sage_())
def _eval_as_leading_term(self, x, logx=None, cdir=0):
from sympy import PoleError
arg = self.args[0]
x0 = arg.subs(x, 0)
if x0.is_integer and x0.is_nonpositive:
n = -x0
res = (-1)**n/self.func(n + 1)
return res/(arg + n).as_leading_term(x)
elif not x0.is_infinite:
return self.func(x0)
raise PoleError()
###############################################################################
################## LOWER and UPPER INCOMPLETE GAMMA FUNCTIONS #################
###############################################################################
class lowergamma(Function):
r"""
The lower incomplete gamma function.
Explanation
===========
It can be defined as the meromorphic continuation of
.. math::
\gamma(s, x) := \int_0^x t^{s-1} e^{-t} \mathrm{d}t = \Gamma(s) - \Gamma(s, x).
This can be shown to be the same as
.. math::
\gamma(s, x) = \frac{x^s}{s} {}_1F_1\left({s \atop s+1} \middle| -x\right),
where ${}_1F_1$ is the (confluent) hypergeometric function.
Examples
========
>>> from sympy import lowergamma, S
>>> from sympy.abc import s, x
>>> lowergamma(s, x)
lowergamma(s, x)
>>> lowergamma(3, x)
-2*(x**2/2 + x + 1)*exp(-x) + 2
>>> lowergamma(-S(1)/2, x)
-2*sqrt(pi)*erf(sqrt(x)) - 2*exp(-x)/sqrt(x)
See Also
========
gamma: Gamma function.
uppergamma: Upper incomplete gamma function.
polygamma: Polygamma function.
loggamma: Log Gamma function.
digamma: Digamma function.
trigamma: Trigamma function.
beta: Euler Beta function.
References
==========
.. [1] https://en.wikipedia.org/wiki/Incomplete_gamma_function#Lower_incomplete_Gamma_function
.. [2] Abramowitz, Milton; Stegun, Irene A., eds. (1965), Chapter 6,
Section 5, Handbook of Mathematical Functions with Formulas, Graphs,
and Mathematical Tables
.. [3] http://dlmf.nist.gov/8
.. [4] http://functions.wolfram.com/GammaBetaErf/Gamma2/
.. [5] http://functions.wolfram.com/GammaBetaErf/Gamma3/
"""
def fdiff(self, argindex=2):
from sympy import meijerg, unpolarify
if argindex == 2:
a, z = self.args
return exp(-unpolarify(z))*z**(a - 1)
elif argindex == 1:
a, z = self.args
return gamma(a)*digamma(a) - log(z)*uppergamma(a, z) \
- meijerg([], [1, 1], [0, 0, a], [], z)
else:
raise ArgumentIndexError(self, argindex)
@classmethod
def eval(cls, a, x):
# For lack of a better place, we use this one to extract branching
# information. The following can be
# found in the literature (c/f references given above), albeit scattered:
# 1) For fixed x != 0, lowergamma(s, x) is an entire function of s
# 2) For fixed positive integers s, lowergamma(s, x) is an entire
# function of x.
# 3) For fixed non-positive integers s,
# lowergamma(s, exp(I*2*pi*n)*x) =
# 2*pi*I*n*(-1)**(-s)/factorial(-s) + lowergamma(s, x)
# (this follows from lowergamma(s, x).diff(x) = x**(s-1)*exp(-x)).
# 4) For fixed non-integral s,
# lowergamma(s, x) = x**s*gamma(s)*lowergamma_unbranched(s, x),
# where lowergamma_unbranched(s, x) is an entire function (in fact
# of both s and x), i.e.
# lowergamma(s, exp(2*I*pi*n)*x) = exp(2*pi*I*n*a)*lowergamma(a, x)
from sympy import unpolarify, I
if x is S.Zero:
return S.Zero
nx, n = x.extract_branch_factor()
if a.is_integer and a.is_positive:
nx = unpolarify(x)
if nx != x:
return lowergamma(a, nx)
elif a.is_integer and a.is_nonpositive:
if n != 0:
return 2*pi*I*n*(-1)**(-a)/factorial(-a) + lowergamma(a, nx)
elif n != 0:
return exp(2*pi*I*n*a)*lowergamma(a, nx)
# Special values.
if a.is_Number:
if a is S.One:
return S.One - exp(-x)
elif a is S.Half:
return sqrt(pi)*erf(sqrt(x))
elif a.is_Integer or (2*a).is_Integer:
b = a - 1
if b.is_positive:
if a.is_integer:
return factorial(b) - exp(-x) * factorial(b) * Add(*[x ** k / factorial(k) for k in range(a)])
else:
return gamma(a)*(lowergamma(S.Half, x)/sqrt(pi) - exp(-x)*Add(*[x**(k - S.Half)/gamma(S.Half + k) for k in range(1, a + S.Half)]))
if not a.is_Integer:
return (-1)**(S.Half - a)*pi*erf(sqrt(x))/gamma(1 - a) + exp(-x)*Add(*[x**(k + a - 1)*gamma(a)/gamma(a + k) for k in range(1, Rational(3, 2) - a)])
if x.is_zero:
return S.Zero
def _eval_evalf(self, prec):
from mpmath import mp, workprec
from sympy import Expr
if all(x.is_number for x in self.args):
a = self.args[0]._to_mpmath(prec)
z = self.args[1]._to_mpmath(prec)
with workprec(prec):
res = mp.gammainc(a, 0, z)
return Expr._from_mpmath(res, prec)
else:
return self
def _eval_conjugate(self):
x = self.args[1]
if x not in (S.Zero, S.NegativeInfinity):
return self.func(self.args[0].conjugate(), x.conjugate())
def _eval_is_meromorphic(self, x, a):
# By https://en.wikipedia.org/wiki/Incomplete_gamma_function#Holomorphic_extension,
# lowergamma(s, z) = z**s*gamma(s)*gammastar(s, z),
# where gammastar(s, z) is holomorphic for all s and z.
# Hence the singularities of lowergamma are z = 0 (branch
# point) and nonpositive integer values of s (poles of gamma(s)).
s, z = self.args
args_merom = fuzzy_and([z._eval_is_meromorphic(x, a),
s._eval_is_meromorphic(x, a)])
if not args_merom:
return args_merom
z0 = z.subs(x, a)
if s.is_integer:
return fuzzy_and([s.is_positive, z0.is_finite])
s0 = s.subs(x, a)
return fuzzy_and([s0.is_finite, z0.is_finite, fuzzy_not(z0.is_zero)])
def _eval_aseries(self, n, args0, x, logx):
from sympy import O
s, z = self.args
if args0[0] is S.Infinity and not z.has(x):
coeff = z**s*exp(-z)
sum_expr = sum(z**k/rf(s, k + 1) for k in range(n - 1))
o = O(z**s*s**(-n))
return coeff*sum_expr + o
return super()._eval_aseries(n, args0, x, logx)
def _eval_rewrite_as_uppergamma(self, s, x, **kwargs):
return gamma(s) - uppergamma(s, x)
def _eval_rewrite_as_expint(self, s, x, **kwargs):
from sympy import expint
if s.is_integer and s.is_nonpositive:
return self
return self.rewrite(uppergamma).rewrite(expint)
def _eval_is_zero(self):
x = self.args[1]
if x.is_zero:
return True
class uppergamma(Function):
r"""
The upper incomplete gamma function.
Explanation
===========
It can be defined as the meromorphic continuation of
.. math::
\Gamma(s, x) := \int_x^\infty t^{s-1} e^{-t} \mathrm{d}t = \Gamma(s) - \gamma(s, x).
where $\gamma(s, x)$ is the lower incomplete gamma function,
:class:`lowergamma`. This can be shown to be the same as
.. math::
\Gamma(s, x) = \Gamma(s) - \frac{x^s}{s} {}_1F_1\left({s \atop s+1} \middle| -x\right),
where ${}_1F_1$ is the (confluent) hypergeometric function.
The upper incomplete gamma function is also essentially equivalent to the
generalized exponential integral:
.. math::
\operatorname{E}_{n}(x) = \int_{1}^{\infty}{\frac{e^{-xt}}{t^n} \, dt} = x^{n-1}\Gamma(1-n,x).
Examples
========
>>> from sympy import uppergamma, S
>>> from sympy.abc import s, x
>>> uppergamma(s, x)
uppergamma(s, x)
>>> uppergamma(3, x)
2*(x**2/2 + x + 1)*exp(-x)
>>> uppergamma(-S(1)/2, x)
-2*sqrt(pi)*erfc(sqrt(x)) + 2*exp(-x)/sqrt(x)
>>> uppergamma(-2, x)
expint(3, x)/x**2
See Also
========
gamma: Gamma function.
lowergamma: Lower incomplete gamma function.
polygamma: Polygamma function.
loggamma: Log Gamma function.
digamma: Digamma function.
trigamma: Trigamma function.
beta: Euler Beta function.
References
==========
.. [1] https://en.wikipedia.org/wiki/Incomplete_gamma_function#Upper_incomplete_Gamma_function
.. [2] Abramowitz, Milton; Stegun, Irene A., eds. (1965), Chapter 6,
Section 5, Handbook of Mathematical Functions with Formulas, Graphs,
and Mathematical Tables
.. [3] http://dlmf.nist.gov/8
.. [4] http://functions.wolfram.com/GammaBetaErf/Gamma2/
.. [5] http://functions.wolfram.com/GammaBetaErf/Gamma3/
.. [6] https://en.wikipedia.org/wiki/Exponential_integral#Relation_with_other_functions
"""
def fdiff(self, argindex=2):
from sympy import meijerg, unpolarify
if argindex == 2:
a, z = self.args
return -exp(-unpolarify(z))*z**(a - 1)
elif argindex == 1:
a, z = self.args
return uppergamma(a, z)*log(z) + meijerg([], [1, 1], [0, 0, a], [], z)
else:
raise ArgumentIndexError(self, argindex)
def _eval_evalf(self, prec):
from mpmath import mp, workprec
from sympy import Expr
if all(x.is_number for x in self.args):
a = self.args[0]._to_mpmath(prec)
z = self.args[1]._to_mpmath(prec)
with workprec(prec):
res = mp.gammainc(a, z, mp.inf)
return Expr._from_mpmath(res, prec)
return self
@classmethod
def eval(cls, a, z):
from sympy import unpolarify, I, expint
if z.is_Number:
if z is S.NaN:
return S.NaN
elif z is S.Infinity:
return S.Zero
elif z.is_zero:
if re(a).is_positive:
return gamma(a)
# We extract branching information here. C/f lowergamma.
nx, n = z.extract_branch_factor()
if a.is_integer and a.is_positive:
nx = unpolarify(z)
if z != nx:
return uppergamma(a, nx)
elif a.is_integer and a.is_nonpositive:
if n != 0:
return -2*pi*I*n*(-1)**(-a)/factorial(-a) + uppergamma(a, nx)
elif n != 0:
return gamma(a)*(1 - exp(2*pi*I*n*a)) + exp(2*pi*I*n*a)*uppergamma(a, nx)
# Special values.
if a.is_Number:
if a is S.Zero and z.is_positive:
return -Ei(-z)
elif a is S.One:
return exp(-z)
elif a is S.Half:
return sqrt(pi)*erfc(sqrt(z))
elif a.is_Integer or (2*a).is_Integer:
b = a - 1
if b.is_positive:
if a.is_integer:
return exp(-z) * factorial(b) * Add(*[z**k / factorial(k) for k in range(a)])
else:
return gamma(a) * erfc(sqrt(z)) + (-1)**(a - S(3)/2) * exp(-z) * sqrt(z) * Add(*[gamma(-S.Half - k) * (-z)**k / gamma(1-a) for k in range(a - S.Half)])
elif b.is_Integer:
return expint(-b, z)*unpolarify(z)**(b + 1)
if not a.is_Integer:
return (-1)**(S.Half - a) * pi*erfc(sqrt(z))/gamma(1-a) - z**a * exp(-z) * Add(*[z**k * gamma(a) / gamma(a+k+1) for k in range(S.Half - a)])
if a.is_zero and z.is_positive:
return -Ei(-z)
if z.is_zero and re(a).is_positive:
return gamma(a)
def _eval_conjugate(self):
z = self.args[1]
if not z in (S.Zero, S.NegativeInfinity):
return self.func(self.args[0].conjugate(), z.conjugate())
def _eval_is_meromorphic(self, x, a):
return lowergamma._eval_is_meromorphic(self, x, a)
def _eval_rewrite_as_lowergamma(self, s, x, **kwargs):
return gamma(s) - lowergamma(s, x)
def _eval_rewrite_as_tractable(self, s, x, **kwargs):
return exp(loggamma(s)) - lowergamma(s, x)
def _eval_rewrite_as_expint(self, s, x, **kwargs):
from sympy import expint
return expint(1 - s, x)*x**s
def _sage_(self):
import sage.all as sage
return sage.gamma(self.args[0]._sage_(), self.args[1]._sage_())
###############################################################################
###################### POLYGAMMA and LOGGAMMA FUNCTIONS #######################
###############################################################################
class polygamma(Function):
r"""
The function ``polygamma(n, z)`` returns ``log(gamma(z)).diff(n + 1)``.
Explanation
===========
It is a meromorphic function on $\mathbb{C}$ and defined as the $(n+1)$-th
derivative of the logarithm of the gamma function:
.. math::
\psi^{(n)} (z) := \frac{\mathrm{d}^{n+1}}{\mathrm{d} z^{n+1}} \log\Gamma(z).
Examples
========
Several special values are known:
>>> from sympy import S, polygamma
>>> polygamma(0, 1)
-EulerGamma
>>> polygamma(0, 1/S(2))
-2*log(2) - EulerGamma
>>> polygamma(0, 1/S(3))
-log(3) - sqrt(3)*pi/6 - EulerGamma - log(sqrt(3))
>>> polygamma(0, 1/S(4))
-pi/2 - log(4) - log(2) - EulerGamma
>>> polygamma(0, 2)
1 - EulerGamma
>>> polygamma(0, 23)
19093197/5173168 - EulerGamma
>>> from sympy import oo, I
>>> polygamma(0, oo)
oo
>>> polygamma(0, -oo)
oo
>>> polygamma(0, I*oo)
oo
>>> polygamma(0, -I*oo)
oo
Differentiation with respect to $x$ is supported:
>>> from sympy import Symbol, diff
>>> x = Symbol("x")
>>> diff(polygamma(0, x), x)
polygamma(1, x)
>>> diff(polygamma(0, x), x, 2)
polygamma(2, x)
>>> diff(polygamma(0, x), x, 3)
polygamma(3, x)
>>> diff(polygamma(1, x), x)
polygamma(2, x)
>>> diff(polygamma(1, x), x, 2)
polygamma(3, x)
>>> diff(polygamma(2, x), x)
polygamma(3, x)
>>> diff(polygamma(2, x), x, 2)
polygamma(4, x)
>>> n = Symbol("n")
>>> diff(polygamma(n, x), x)
polygamma(n + 1, x)
>>> diff(polygamma(n, x), x, 2)
polygamma(n + 2, x)
We can rewrite ``polygamma`` functions in terms of harmonic numbers:
>>> from sympy import harmonic
>>> polygamma(0, x).rewrite(harmonic)
harmonic(x - 1) - EulerGamma
>>> polygamma(2, x).rewrite(harmonic)
2*harmonic(x - 1, 3) - 2*zeta(3)
>>> ni = Symbol("n", integer=True)
>>> polygamma(ni, x).rewrite(harmonic)
(-1)**(n + 1)*(-harmonic(x - 1, n + 1) + zeta(n + 1))*factorial(n)
See Also
========
gamma: Gamma function.
lowergamma: Lower incomplete gamma function.
uppergamma: Upper incomplete gamma function.
loggamma: Log Gamma function.
digamma: Digamma function.
trigamma: Trigamma function.
beta: Euler Beta function.
References
==========
.. [1] https://en.wikipedia.org/wiki/Polygamma_function
.. [2] http://mathworld.wolfram.com/PolygammaFunction.html
.. [3] http://functions.wolfram.com/GammaBetaErf/PolyGamma/
.. [4] http://functions.wolfram.com/GammaBetaErf/PolyGamma2/
"""
def _eval_evalf(self, prec):
n = self.args[0]
# the mpmath polygamma implementation valid only for nonnegative integers
if n.is_number and n.is_real:
if (n.is_integer or n == int(n)) and n.is_nonnegative:
return super()._eval_evalf(prec)
def fdiff(self, argindex=2):
if argindex == 2:
n, z = self.args[:2]
return polygamma(n + 1, z)
else:
raise ArgumentIndexError(self, argindex)
def _eval_is_real(self):
if self.args[0].is_positive and self.args[1].is_positive:
return True
def _eval_is_complex(self):
z = self.args[1]
is_negative_integer = fuzzy_and([z.is_negative, z.is_integer])
return fuzzy_and([z.is_complex, fuzzy_not(is_negative_integer)])
def _eval_is_positive(self):
if self.args[0].is_positive and self.args[1].is_positive:
return self.args[0].is_odd
def _eval_is_negative(self):
if self.args[0].is_positive and self.args[1].is_positive:
return self.args[0].is_even
def _eval_aseries(self, n, args0, x, logx):
from sympy import Order
if args0[1] != oo or not \
(self.args[0].is_Integer and self.args[0].is_nonnegative):
return super()._eval_aseries(n, args0, x, logx)
z = self.args[1]
N = self.args[0]
if N == 0:
# digamma function series
# Abramowitz & Stegun, p. 259, 6.3.18
r = log(z) - 1/(2*z)
o = None
if n < 2:
o = Order(1/z, x)
else:
m = ceiling((n + 1)//2)
l = [bernoulli(2*k) / (2*k*z**(2*k)) for k in range(1, m)]
r -= Add(*l)
o = Order(1/z**n, x)
return r._eval_nseries(x, n, logx) + o
else:
# proper polygamma function
# Abramowitz & Stegun, p. 260, 6.4.10
# We return terms to order higher than O(x**n) on purpose
# -- otherwise we would not be able to return any terms for
# quite a long time!
fac = gamma(N)
e0 = fac + N*fac/(2*z)
m = ceiling((n + 1)//2)
for k in range(1, m):
fac = fac*(2*k + N - 1)*(2*k + N - 2) / ((2*k)*(2*k - 1))
e0 += bernoulli(2*k)*fac/z**(2*k)
o = Order(1/z**(2*m), x)
if n == 0:
o = Order(1/z, x)
elif n == 1:
o = Order(1/z**2, x)
r = e0._eval_nseries(z, n, logx) + o
return (-1 * (-1/z)**N * r)._eval_nseries(x, n, logx)
@classmethod
def eval(cls, n, z):
n, z = map(sympify, (n, z))
from sympy import unpolarify
if n.is_integer:
if n.is_nonnegative:
nz = unpolarify(z)
if z != nz:
return polygamma(n, nz)
if n.is_positive:
if z is S.Half:
return (-1)**(n + 1)*factorial(n)*(2**(n + 1) - 1)*zeta(n + 1)
if n is S.NegativeOne:
return loggamma(z)
else:
if z.is_Number:
if z is S.NaN:
return S.NaN
elif z is S.Infinity:
if n.is_Number:
if n.is_zero:
return S.Infinity
else:
return S.Zero
if n.is_zero:
return S.Infinity
elif z.is_Integer:
if z.is_nonpositive:
return S.ComplexInfinity
else:
if n.is_zero:
return -S.EulerGamma + harmonic(z - 1, 1)
elif n.is_odd:
return (-1)**(n + 1)*factorial(n)*zeta(n + 1, z)
if n.is_zero:
if z is S.NaN:
return S.NaN
elif z.is_Rational:
p, q = z.as_numer_denom()
# only expand for small denominators to avoid creating long expressions
if q <= 5:
return expand_func(polygamma(S.Zero, z, evaluate=False))
elif z in (S.Infinity, S.NegativeInfinity):
return S.Infinity
else:
t = z.extract_multiplicatively(S.ImaginaryUnit)
if t in (S.Infinity, S.NegativeInfinity):
return S.Infinity
# TODO n == 1 also can do some rational z
def _eval_expand_func(self, **hints):
n, z = self.args
if n.is_Integer and n.is_nonnegative:
if z.is_Add:
coeff = z.args[0]
if coeff.is_Integer:
e = -(n + 1)
if coeff > 0:
tail = Add(*[Pow(
z - i, e) for i in range(1, int(coeff) + 1)])
else:
tail = -Add(*[Pow(
z + i, e) for i in range(0, int(-coeff))])
return polygamma(n, z - coeff) + (-1)**n*factorial(n)*tail
elif z.is_Mul:
coeff, z = z.as_two_terms()
if coeff.is_Integer and coeff.is_positive:
tail = [ polygamma(n, z + Rational(
i, coeff)) for i in range(0, int(coeff)) ]
if n == 0:
return Add(*tail)/coeff + log(coeff)
else:
return Add(*tail)/coeff**(n + 1)
z *= coeff
if n == 0 and z.is_Rational:
p, q = z.as_numer_denom()
# Reference:
# Values of the polygamma functions at rational arguments, J. Choi, 2007
part_1 = -S.EulerGamma - pi * cot(p * pi / q) / 2 - log(q) + Add(
*[cos(2 * k * pi * p / q) * log(2 * sin(k * pi / q)) for k in range(1, q)])
if z > 0:
n = floor(z)
z0 = z - n
return part_1 + Add(*[1 / (z0 + k) for k in range(n)])
elif z < 0:
n = floor(1 - z)
z0 = z + n
return part_1 - Add(*[1 / (z0 - 1 - k) for k in range(n)])
return polygamma(n, z)
def _eval_rewrite_as_zeta(self, n, z, **kwargs):
if n.is_integer:
if (n - S.One).is_nonnegative:
return (-1)**(n + 1)*factorial(n)*zeta(n + 1, z)
def _eval_rewrite_as_harmonic(self, n, z, **kwargs):
if n.is_integer:
if n.is_zero:
return harmonic(z - 1) - S.EulerGamma
else:
return S.NegativeOne**(n+1) * factorial(n) * (zeta(n+1) - harmonic(z-1, n+1))
def _eval_as_leading_term(self, x, logx=None, cdir=0):
from sympy import Order
n, z = [a.as_leading_term(x) for a in self.args]
o = Order(z, x)
if n == 0 and o.contains(1/x):
return o.getn() * log(x)
else:
return self.func(n, z)
class loggamma(Function):
r"""
The ``loggamma`` function implements the logarithm of the
gamma function (i.e., $\log\Gamma(x)$).
Examples
========
Several special values are known. For numerical integral
arguments we have:
>>> from sympy import loggamma
>>> loggamma(-2)
oo
>>> loggamma(0)
oo
>>> loggamma(1)
0
>>> loggamma(2)
0
>>> loggamma(3)
log(2)
And for symbolic values:
>>> from sympy import Symbol
>>> n = Symbol("n", integer=True, positive=True)
>>> loggamma(n)
log(gamma(n))
>>> loggamma(-n)
oo
For half-integral values:
>>> from sympy import S
>>> loggamma(S(5)/2)
log(3*sqrt(pi)/4)
>>> loggamma(n/2)
log(2**(1 - n)*sqrt(pi)*gamma(n)/gamma(n/2 + 1/2))
And general rational arguments:
>>> from sympy import expand_func
>>> L = loggamma(S(16)/3)
>>> expand_func(L).doit()
-5*log(3) + loggamma(1/3) + log(4) + log(7) + log(10) + log(13)
>>> L = loggamma(S(19)/4)
>>> expand_func(L).doit()
-4*log(4) + loggamma(3/4) + log(3) + log(7) + log(11) + log(15)
>>> L = loggamma(S(23)/7)
>>> expand_func(L).doit()
-3*log(7) + log(2) + loggamma(2/7) + log(9) + log(16)
The ``loggamma`` function has the following limits towards infinity:
>>> from sympy import oo
>>> loggamma(oo)
oo
>>> loggamma(-oo)
zoo
The ``loggamma`` function obeys the mirror symmetry
if $x \in \mathbb{C} \setminus \{-\infty, 0\}$:
>>> from sympy.abc import x
>>> from sympy import conjugate
>>> conjugate(loggamma(x))
loggamma(conjugate(x))
Differentiation with respect to $x$ is supported:
>>> from sympy import diff
>>> diff(loggamma(x), x)
polygamma(0, x)
Series expansion is also supported:
>>> from sympy import series
>>> series(loggamma(x), x, 0, 4).cancel()
-log(x) - EulerGamma*x + pi**2*x**2/12 + x**3*polygamma(2, 1)/6 + O(x**4)
We can numerically evaluate the ``gamma`` function to arbitrary precision
on the whole complex plane:
>>> from sympy import I
>>> loggamma(5).evalf(30)
3.17805383034794561964694160130
>>> loggamma(I).evalf(20)
-0.65092319930185633889 - 1.8724366472624298171*I
See Also
========
gamma: Gamma function.
lowergamma: Lower incomplete gamma function.
uppergamma: Upper incomplete gamma function.
polygamma: Polygamma function.
digamma: Digamma function.
trigamma: Trigamma function.
beta: Euler Beta function.
References
==========
.. [1] https://en.wikipedia.org/wiki/Gamma_function
.. [2] http://dlmf.nist.gov/5
.. [3] http://mathworld.wolfram.com/LogGammaFunction.html
.. [4] http://functions.wolfram.com/GammaBetaErf/LogGamma/
"""
@classmethod
def eval(cls, z):
z = sympify(z)
if z.is_integer:
if z.is_nonpositive:
return S.Infinity
elif z.is_positive:
return log(gamma(z))
elif z.is_rational:
p, q = z.as_numer_denom()
# Half-integral values:
if p.is_positive and q == 2:
return log(sqrt(S.Pi) * 2**(1 - p) * gamma(p) / gamma((p + 1)*S.Half))
if z is S.Infinity:
return S.Infinity
elif abs(z) is S.Infinity:
return S.ComplexInfinity
if z is S.NaN:
return S.NaN
def _eval_expand_func(self, **hints):
from sympy import Sum
z = self.args[0]
if z.is_Rational:
p, q = z.as_numer_denom()
# General rational arguments (u + p/q)
# Split z as n + p/q with p < q
n = p // q
p = p - n*q
if p.is_positive and q.is_positive and p < q:
k = Dummy("k")
if n.is_positive:
return loggamma(p / q) - n*log(q) + Sum(log((k - 1)*q + p), (k, 1, n))
elif n.is_negative:
return loggamma(p / q) - n*log(q) + S.Pi*S.ImaginaryUnit*n - Sum(log(k*q - p), (k, 1, -n))
elif n.is_zero:
return loggamma(p / q)
return self
def _eval_nseries(self, x, n, logx=None, cdir=0):
x0 = self.args[0].limit(x, 0)
if x0.is_zero:
f = self._eval_rewrite_as_intractable(*self.args)
return f._eval_nseries(x, n, logx)
return super()._eval_nseries(x, n, logx)
def _eval_aseries(self, n, args0, x, logx):
from sympy import Order
if args0[0] != oo:
return super()._eval_aseries(n, args0, x, logx)
z = self.args[0]
r = log(z)*(z - S.Half) - z + log(2*pi)/2
l = [bernoulli(2*k) / (2*k*(2*k - 1)*z**(2*k - 1)) for k in range(1, n)]
o = None
if n == 0:
o = Order(1, x)
else:
o = Order(1/z**n, x)
# It is very inefficient to first add the order and then do the nseries
return (r + Add(*l))._eval_nseries(x, n, logx) + o
def _eval_rewrite_as_intractable(self, z, **kwargs):
return log(gamma(z))
def _eval_is_real(self):
z = self.args[0]
if z.is_positive:
return True
elif z.is_nonpositive:
return False
def _eval_conjugate(self):
z = self.args[0]
if not z in (S.Zero, S.NegativeInfinity):
return self.func(z.conjugate())
def fdiff(self, argindex=1):
if argindex == 1:
return polygamma(0, self.args[0])
else:
raise ArgumentIndexError(self, argindex)
def _sage_(self):
import sage.all as sage
return sage.log_gamma(self.args[0]._sage_())
class digamma(Function):
r"""
The ``digamma`` function is the first derivative of the ``loggamma``
function
.. math::
\psi(x) := \frac{\mathrm{d}}{\mathrm{d} z} \log\Gamma(z)
= \frac{\Gamma'(z)}{\Gamma(z) }.
In this case, ``digamma(z) = polygamma(0, z)``.
Examples
========
>>> from sympy import digamma
>>> digamma(0)
zoo
>>> from sympy import Symbol
>>> z = Symbol('z')
>>> digamma(z)
polygamma(0, z)
To retain ``digamma`` as it is:
>>> digamma(0, evaluate=False)
digamma(0)
>>> digamma(z, evaluate=False)
digamma(z)
See Also
========
gamma: Gamma function.
lowergamma: Lower incomplete gamma function.
uppergamma: Upper incomplete gamma function.
polygamma: Polygamma function.
loggamma: Log Gamma function.
trigamma: Trigamma function.
beta: Euler Beta function.
References
==========
.. [1] https://en.wikipedia.org/wiki/Digamma_function
.. [2] http://mathworld.wolfram.com/DigammaFunction.html
.. [3] http://functions.wolfram.com/GammaBetaErf/PolyGamma2/
"""
def _eval_evalf(self, prec):
z = self.args[0]
return polygamma(0, z).evalf(prec)
def fdiff(self, argindex=1):
z = self.args[0]
return polygamma(0, z).fdiff()
def _eval_is_real(self):
z = self.args[0]
return polygamma(0, z).is_real
def _eval_is_positive(self):
z = self.args[0]
return polygamma(0, z).is_positive
def _eval_is_negative(self):
z = self.args[0]
return polygamma(0, z).is_negative
def _eval_aseries(self, n, args0, x, logx):
as_polygamma = self.rewrite(polygamma)
args0 = [S.Zero,] + args0
return as_polygamma._eval_aseries(n, args0, x, logx)
@classmethod
def eval(cls, z):
return polygamma(0, z)
def _eval_expand_func(self, **hints):
z = self.args[0]
return polygamma(0, z).expand(func=True)
def _eval_rewrite_as_harmonic(self, z, **kwargs):
return harmonic(z - 1) - S.EulerGamma
def _eval_rewrite_as_polygamma(self, z, **kwargs):
return polygamma(0, z)
def _eval_as_leading_term(self, x, logx=None, cdir=0):
z = self.args[0]
return polygamma(0, z).as_leading_term(x)
class trigamma(Function):
r"""
The ``trigamma`` function is the second derivative of the ``loggamma``
function
.. math::
\psi^{(1)}(z) := \frac{\mathrm{d}^{2}}{\mathrm{d} z^{2}} \log\Gamma(z).
In this case, ``trigamma(z) = polygamma(1, z)``.
Examples
========
>>> from sympy import trigamma
>>> trigamma(0)
zoo
>>> from sympy import Symbol
>>> z = Symbol('z')
>>> trigamma(z)
polygamma(1, z)
To retain ``trigamma`` as it is:
>>> trigamma(0, evaluate=False)
trigamma(0)
>>> trigamma(z, evaluate=False)
trigamma(z)
See Also
========
gamma: Gamma function.
lowergamma: Lower incomplete gamma function.
uppergamma: Upper incomplete gamma function.
polygamma: Polygamma function.
loggamma: Log Gamma function.
digamma: Digamma function.
beta: Euler Beta function.
References
==========
.. [1] https://en.wikipedia.org/wiki/Trigamma_function
.. [2] http://mathworld.wolfram.com/TrigammaFunction.html
.. [3] http://functions.wolfram.com/GammaBetaErf/PolyGamma2/
"""
def _eval_evalf(self, prec):
z = self.args[0]
return polygamma(1, z).evalf(prec)
def fdiff(self, argindex=1):
z = self.args[0]
return polygamma(1, z).fdiff()
def _eval_is_real(self):
z = self.args[0]
return polygamma(1, z).is_real
def _eval_is_positive(self):
z = self.args[0]
return polygamma(1, z).is_positive
def _eval_is_negative(self):
z = self.args[0]
return polygamma(1, z).is_negative
def _eval_aseries(self, n, args0, x, logx):
as_polygamma = self.rewrite(polygamma)
args0 = [S.One,] + args0
return as_polygamma._eval_aseries(n, args0, x, logx)
@classmethod
def eval(cls, z):
return polygamma(1, z)
def _eval_expand_func(self, **hints):
z = self.args[0]
return polygamma(1, z).expand(func=True)
def _eval_rewrite_as_zeta(self, z, **kwargs):
return zeta(2, z)
def _eval_rewrite_as_polygamma(self, z, **kwargs):
return polygamma(1, z)
def _eval_rewrite_as_harmonic(self, z, **kwargs):
return -harmonic(z - 1, 2) + S.Pi**2 / 6
def _eval_as_leading_term(self, x, logx=None, cdir=0):
z = self.args[0]
return polygamma(1, z).as_leading_term(x)
###############################################################################
##################### COMPLETE MULTIVARIATE GAMMA FUNCTION ####################
###############################################################################
class multigamma(Function):
r"""
The multivariate gamma function is a generalization of the gamma function
.. math::
\Gamma_p(z) = \pi^{p(p-1)/4}\prod_{k=1}^p \Gamma[z + (1 - k)/2].
In a special case, ``multigamma(x, 1) = gamma(x)``.
Examples
========
>>> from sympy import S, multigamma
>>> from sympy import Symbol
>>> x = Symbol('x')
>>> p = Symbol('p', positive=True, integer=True)
>>> multigamma(x, p)
pi**(p*(p - 1)/4)*Product(gamma(-_k/2 + x + 1/2), (_k, 1, p))
Several special values are known:
>>> multigamma(1, 1)
1
>>> multigamma(4, 1)
6
>>> multigamma(S(3)/2, 1)
sqrt(pi)/2
Writing ``multigamma`` in terms of the ``gamma`` function:
>>> multigamma(x, 1)
gamma(x)
>>> multigamma(x, 2)
sqrt(pi)*gamma(x)*gamma(x - 1/2)
>>> multigamma(x, 3)
pi**(3/2)*gamma(x)*gamma(x - 1)*gamma(x - 1/2)
Parameters
==========
p : order or dimension of the multivariate gamma function
See Also
========
gamma, lowergamma, uppergamma, polygamma, loggamma, digamma, trigamma,
beta
References
==========
.. [1] https://en.wikipedia.org/wiki/Multivariate_gamma_function
"""
unbranched = True
def fdiff(self, argindex=2):
from sympy import Sum
if argindex == 2:
x, p = self.args
k = Dummy("k")
return self.func(x, p)*Sum(polygamma(0, x + (1 - k)/2), (k, 1, p))
else:
raise ArgumentIndexError(self, argindex)
@classmethod
def eval(cls, x, p):
from sympy import Product
x, p = map(sympify, (x, p))
if p.is_positive is False or p.is_integer is False:
raise ValueError('Order parameter p must be positive integer.')
k = Dummy("k")
return (pi**(p*(p - 1)/4)*Product(gamma(x + (1 - k)/2),
(k, 1, p))).doit()
def _eval_conjugate(self):
x, p = self.args
return self.func(x.conjugate(), p)
def _eval_is_real(self):
x, p = self.args
y = 2*x
if y.is_integer and (y <= (p - 1)) is True:
return False
if intlike(y) and (y <= (p - 1)):
return False
if y > (p - 1) or y.is_noninteger:
return True
|
0bb159b2daa2e4bb4f3020830a036fd6f4639d6e2a0f702f7e70abcd5f46e37c | """ Riemann zeta and related function. """
from sympy import Add
from sympy.core import Function, S, sympify, pi, I
from sympy.core.function import ArgumentIndexError
from sympy.functions.combinatorial.numbers import bernoulli, factorial, harmonic
from sympy.functions.elementary.complexes import re
from sympy.functions.elementary.exponential import log, exp_polar
from sympy.functions.elementary.miscellaneous import sqrt
###############################################################################
###################### LERCH TRANSCENDENT #####################################
###############################################################################
class lerchphi(Function):
r"""
Lerch transcendent (Lerch phi function).
Explanation
===========
For $\operatorname{Re}(a) > 0$, $|z| < 1$ and $s \in \mathbb{C}$, the
Lerch transcendent is defined as
.. math :: \Phi(z, s, a) = \sum_{n=0}^\infty \frac{z^n}{(n + a)^s},
where the standard branch of the argument is used for $n + a$,
and by analytic continuation for other values of the parameters.
A commonly used related function is the Lerch zeta function, defined by
.. math:: L(q, s, a) = \Phi(e^{2\pi i q}, s, a).
**Analytic Continuation and Branching Behavior**
It can be shown that
.. math:: \Phi(z, s, a) = z\Phi(z, s, a+1) + a^{-s}.
This provides the analytic continuation to $\operatorname{Re}(a) \le 0$.
Assume now $\operatorname{Re}(a) > 0$. The integral representation
.. math:: \Phi_0(z, s, a) = \int_0^\infty \frac{t^{s-1} e^{-at}}{1 - ze^{-t}}
\frac{\mathrm{d}t}{\Gamma(s)}
provides an analytic continuation to $\mathbb{C} - [1, \infty)$.
Finally, for $x \in (1, \infty)$ we find
.. math:: \lim_{\epsilon \to 0^+} \Phi_0(x + i\epsilon, s, a)
-\lim_{\epsilon \to 0^+} \Phi_0(x - i\epsilon, s, a)
= \frac{2\pi i \log^{s-1}{x}}{x^a \Gamma(s)},
using the standard branch for both $\log{x}$ and
$\log{\log{x}}$ (a branch of $\log{\log{x}}$ is needed to
evaluate $\log{x}^{s-1}$).
This concludes the analytic continuation. The Lerch transcendent is thus
branched at $z \in \{0, 1, \infty\}$ and
$a \in \mathbb{Z}_{\le 0}$. For fixed $z, a$ outside these
branch points, it is an entire function of $s$.
Examples
========
The Lerch transcendent is a fairly general function, for this reason it does
not automatically evaluate to simpler functions. Use ``expand_func()`` to
achieve this.
If $z=1$, the Lerch transcendent reduces to the Hurwitz zeta function:
>>> from sympy import lerchphi, expand_func
>>> from sympy.abc import z, s, a
>>> expand_func(lerchphi(1, s, a))
zeta(s, a)
More generally, if $z$ is a root of unity, the Lerch transcendent
reduces to a sum of Hurwitz zeta functions:
>>> expand_func(lerchphi(-1, s, a))
zeta(s, a/2)/2**s - zeta(s, a/2 + 1/2)/2**s
If $a=1$, the Lerch transcendent reduces to the polylogarithm:
>>> expand_func(lerchphi(z, s, 1))
polylog(s, z)/z
More generally, if $a$ is rational, the Lerch transcendent reduces
to a sum of polylogarithms:
>>> from sympy import S
>>> expand_func(lerchphi(z, s, S(1)/2))
2**(s - 1)*(polylog(s, sqrt(z))/sqrt(z) -
polylog(s, sqrt(z)*exp_polar(I*pi))/sqrt(z))
>>> expand_func(lerchphi(z, s, S(3)/2))
-2**s/z + 2**(s - 1)*(polylog(s, sqrt(z))/sqrt(z) -
polylog(s, sqrt(z)*exp_polar(I*pi))/sqrt(z))/z
The derivatives with respect to $z$ and $a$ can be computed in
closed form:
>>> lerchphi(z, s, a).diff(z)
(-a*lerchphi(z, s, a) + lerchphi(z, s - 1, a))/z
>>> lerchphi(z, s, a).diff(a)
-s*lerchphi(z, s + 1, a)
See Also
========
polylog, zeta
References
==========
.. [1] Bateman, H.; Erdelyi, A. (1953), Higher Transcendental Functions,
Vol. I, New York: McGraw-Hill. Section 1.11.
.. [2] http://dlmf.nist.gov/25.14
.. [3] https://en.wikipedia.org/wiki/Lerch_transcendent
"""
def _eval_expand_func(self, **hints):
from sympy import exp, I, floor, Add, Poly, Dummy, exp_polar, unpolarify
z, s, a = self.args
if z == 1:
return zeta(s, a)
if s.is_Integer and s <= 0:
t = Dummy('t')
p = Poly((t + a)**(-s), t)
start = 1/(1 - t)
res = S.Zero
for c in reversed(p.all_coeffs()):
res += c*start
start = t*start.diff(t)
return res.subs(t, z)
if a.is_Rational:
# See section 18 of
# Kelly B. Roach. Hypergeometric Function Representations.
# In: Proceedings of the 1997 International Symposium on Symbolic and
# Algebraic Computation, pages 205-211, New York, 1997. ACM.
# TODO should something be polarified here?
add = S.Zero
mul = S.One
# First reduce a to the interaval (0, 1]
if a > 1:
n = floor(a)
if n == a:
n -= 1
a -= n
mul = z**(-n)
add = Add(*[-z**(k - n)/(a + k)**s for k in range(n)])
elif a <= 0:
n = floor(-a) + 1
a += n
mul = z**n
add = Add(*[z**(n - 1 - k)/(a - k - 1)**s for k in range(n)])
m, n = S([a.p, a.q])
zet = exp_polar(2*pi*I/n)
root = z**(1/n)
return add + mul*n**(s - 1)*Add(
*[polylog(s, zet**k*root)._eval_expand_func(**hints)
/ (unpolarify(zet)**k*root)**m for k in range(n)])
# TODO use minpoly instead of ad-hoc methods when issue 5888 is fixed
if isinstance(z, exp) and (z.args[0]/(pi*I)).is_Rational or z in [-1, I, -I]:
# TODO reference?
if z == -1:
p, q = S([1, 2])
elif z == I:
p, q = S([1, 4])
elif z == -I:
p, q = S([-1, 4])
else:
arg = z.args[0]/(2*pi*I)
p, q = S([arg.p, arg.q])
return Add(*[exp(2*pi*I*k*p/q)/q**s*zeta(s, (k + a)/q)
for k in range(q)])
return lerchphi(z, s, a)
def fdiff(self, argindex=1):
z, s, a = self.args
if argindex == 3:
return -s*lerchphi(z, s + 1, a)
elif argindex == 1:
return (lerchphi(z, s - 1, a) - a*lerchphi(z, s, a))/z
else:
raise ArgumentIndexError
def _eval_rewrite_helper(self, z, s, a, target):
res = self._eval_expand_func()
if res.has(target):
return res
else:
return self
def _eval_rewrite_as_zeta(self, z, s, a, **kwargs):
return self._eval_rewrite_helper(z, s, a, zeta)
def _eval_rewrite_as_polylog(self, z, s, a, **kwargs):
return self._eval_rewrite_helper(z, s, a, polylog)
###############################################################################
###################### POLYLOGARITHM ##########################################
###############################################################################
class polylog(Function):
r"""
Polylogarithm function.
Explanation
===========
For $|z| < 1$ and $s \in \mathbb{C}$, the polylogarithm is
defined by
.. math:: \operatorname{Li}_s(z) = \sum_{n=1}^\infty \frac{z^n}{n^s},
where the standard branch of the argument is used for $n$. It admits
an analytic continuation which is branched at $z=1$ (notably not on the
sheet of initial definition), $z=0$ and $z=\infty$.
The name polylogarithm comes from the fact that for $s=1$, the
polylogarithm is related to the ordinary logarithm (see examples), and that
.. math:: \operatorname{Li}_{s+1}(z) =
\int_0^z \frac{\operatorname{Li}_s(t)}{t} \mathrm{d}t.
The polylogarithm is a special case of the Lerch transcendent:
.. math:: \operatorname{Li}_{s}(z) = z \Phi(z, s, 1).
Examples
========
For $z \in \{0, 1, -1\}$, the polylogarithm is automatically expressed
using other functions:
>>> from sympy import polylog
>>> from sympy.abc import s
>>> polylog(s, 0)
0
>>> polylog(s, 1)
zeta(s)
>>> polylog(s, -1)
-dirichlet_eta(s)
If $s$ is a negative integer, $0$ or $1$, the polylogarithm can be
expressed using elementary functions. This can be done using
``expand_func()``:
>>> from sympy import expand_func
>>> from sympy.abc import z
>>> expand_func(polylog(1, z))
-log(1 - z)
>>> expand_func(polylog(0, z))
z/(1 - z)
The derivative with respect to $z$ can be computed in closed form:
>>> polylog(s, z).diff(z)
polylog(s - 1, z)/z
The polylogarithm can be expressed in terms of the lerch transcendent:
>>> from sympy import lerchphi
>>> polylog(s, z).rewrite(lerchphi)
z*lerchphi(z, s, 1)
See Also
========
zeta, lerchphi
"""
@classmethod
def eval(cls, s, z):
s, z = sympify((s, z))
if z is S.One:
return zeta(s)
elif z is S.NegativeOne:
return -dirichlet_eta(s)
elif z is S.Zero:
return S.Zero
elif s == 2:
if z == S.Half:
return pi**2/12 - log(2)**2/2
elif z == 2:
return pi**2/4 - I*pi*log(2)
elif z == -(sqrt(5) - 1)/2:
return -pi**2/15 + log((sqrt(5)-1)/2)**2/2
elif z == -(sqrt(5) + 1)/2:
return -pi**2/10 - log((sqrt(5)+1)/2)**2
elif z == (3 - sqrt(5))/2:
return pi**2/15 - log((sqrt(5)-1)/2)**2
elif z == (sqrt(5) - 1)/2:
return pi**2/10 - log((sqrt(5)-1)/2)**2
if z.is_zero:
return S.Zero
# Make an effort to determine if z is 1 to avoid replacing into
# expression with singularity
zone = z.equals(S.One)
if zone:
return zeta(s)
elif zone is False:
# For s = 0 or -1 use explicit formulas to evaluate, but
# automatically expanding polylog(1, z) to -log(1-z) seems
# undesirable for summation methods based on hypergeometric
# functions
if s is S.Zero:
return z/(1 - z)
elif s is S.NegativeOne:
return z/(1 - z)**2
if s.is_zero:
return z/(1 - z)
# polylog is branched, but not over the unit disk
from sympy.functions.elementary.complexes import (Abs, unpolarify,
polar_lift)
if z.has(exp_polar, polar_lift) and (zone or (Abs(z) <= S.One) == True):
return cls(s, unpolarify(z))
def fdiff(self, argindex=1):
s, z = self.args
if argindex == 2:
return polylog(s - 1, z)/z
raise ArgumentIndexError
def _eval_rewrite_as_lerchphi(self, s, z, **kwargs):
return z*lerchphi(z, s, 1)
def _eval_expand_func(self, **hints):
from sympy import log, expand_mul, Dummy
s, z = self.args
if s == 1:
return -log(1 - z)
if s.is_Integer and s <= 0:
u = Dummy('u')
start = u/(1 - u)
for _ in range(-s):
start = u*start.diff(u)
return expand_mul(start).subs(u, z)
return polylog(s, z)
def _eval_is_zero(self):
z = self.args[1]
if z.is_zero:
return True
def _eval_nseries(self, x, n, logx, cdir=0):
from sympy import ceiling, Order
nu, z = self.args
z0 = z.subs(x, 0)
if z0 is S.NaN:
z0 = z.limit(x, 0, dir='-' if re(cdir).is_negative else '+')
if z0.is_zero:
# In case of powers less than 1, number of terms need to be computed
# separately to avoid repeated callings of _eval_nseries with wrong n
try:
_, exp = z.leadterm(x)
except (ValueError, NotImplementedError):
return self
if exp.is_positive:
newn = ceiling(n/exp)
o = Order(x**n, x)
r = z._eval_nseries(x, n, logx, cdir).removeO()
if r is S.Zero:
return o
term = r
s = [term]
for k in range(2, newn):
term *= r
s.append(term/k**nu)
return Add(*s) + o
return super(polylog, self)._eval_nseries(x, n, logx, cdir)
###############################################################################
###################### HURWITZ GENERALIZED ZETA FUNCTION ######################
###############################################################################
class zeta(Function):
r"""
Hurwitz zeta function (or Riemann zeta function).
Explanation
===========
For $\operatorname{Re}(a) > 0$ and $\operatorname{Re}(s) > 1$, this
function is defined as
.. math:: \zeta(s, a) = \sum_{n=0}^\infty \frac{1}{(n + a)^s},
where the standard choice of argument for $n + a$ is used. For fixed
$a$ with $\operatorname{Re}(a) > 0$ the Hurwitz zeta function admits a
meromorphic continuation to all of $\mathbb{C}$, it is an unbranched
function with a simple pole at $s = 1$.
Analytic continuation to other $a$ is possible under some circumstances,
but this is not typically done.
The Hurwitz zeta function is a special case of the Lerch transcendent:
.. math:: \zeta(s, a) = \Phi(1, s, a).
This formula defines an analytic continuation for all possible values of
$s$ and $a$ (also $\operatorname{Re}(a) < 0$), see the documentation of
:class:`lerchphi` for a description of the branching behavior.
If no value is passed for $a$, by this function assumes a default value
of $a = 1$, yielding the Riemann zeta function.
Examples
========
For $a = 1$ the Hurwitz zeta function reduces to the famous Riemann
zeta function:
.. math:: \zeta(s, 1) = \zeta(s) = \sum_{n=1}^\infty \frac{1}{n^s}.
>>> from sympy import zeta
>>> from sympy.abc import s
>>> zeta(s, 1)
zeta(s)
>>> zeta(s)
zeta(s)
The Riemann zeta function can also be expressed using the Dirichlet eta
function:
>>> from sympy import dirichlet_eta
>>> zeta(s).rewrite(dirichlet_eta)
dirichlet_eta(s)/(1 - 2**(1 - s))
The Riemann zeta function at positive even integer and negative odd integer
values is related to the Bernoulli numbers:
>>> zeta(2)
pi**2/6
>>> zeta(4)
pi**4/90
>>> zeta(-1)
-1/12
The specific formulae are:
.. math:: \zeta(2n) = (-1)^{n+1} \frac{B_{2n} (2\pi)^{2n}}{2(2n)!}
.. math:: \zeta(-n) = -\frac{B_{n+1}}{n+1}
At negative even integers the Riemann zeta function is zero:
>>> zeta(-4)
0
No closed-form expressions are known at positive odd integers, but
numerical evaluation is possible:
>>> zeta(3).n()
1.20205690315959
The derivative of $\zeta(s, a)$ with respect to $a$ can be computed:
>>> from sympy.abc import a
>>> zeta(s, a).diff(a)
-s*zeta(s + 1, a)
However the derivative with respect to $s$ has no useful closed form
expression:
>>> zeta(s, a).diff(s)
Derivative(zeta(s, a), s)
The Hurwitz zeta function can be expressed in terms of the Lerch
transcendent, :class:`~.lerchphi`:
>>> from sympy import lerchphi
>>> zeta(s, a).rewrite(lerchphi)
lerchphi(1, s, a)
See Also
========
dirichlet_eta, lerchphi, polylog
References
==========
.. [1] http://dlmf.nist.gov/25.11
.. [2] https://en.wikipedia.org/wiki/Hurwitz_zeta_function
"""
@classmethod
def eval(cls, z, a_=None):
if a_ is None:
z, a = list(map(sympify, (z, 1)))
else:
z, a = list(map(sympify, (z, a_)))
if a.is_Number:
if a is S.NaN:
return S.NaN
elif a is S.One and a_ is not None:
return cls(z)
# TODO Should a == 0 return S.NaN as well?
if z.is_Number:
if z is S.NaN:
return S.NaN
elif z is S.Infinity:
return S.One
elif z.is_zero:
return S.Half - a
elif z is S.One:
return S.ComplexInfinity
if z.is_integer:
if a.is_Integer:
if z.is_negative:
zeta = (-1)**z * bernoulli(-z + 1)/(-z + 1)
elif z.is_even and z.is_positive:
B, F = bernoulli(z), factorial(z)
zeta = ((-1)**(z/2+1) * 2**(z - 1) * B * pi**z) / F
else:
return
if a.is_negative:
return zeta + harmonic(abs(a), z)
else:
return zeta - harmonic(a - 1, z)
if z.is_zero:
return S.Half - a
def _eval_rewrite_as_dirichlet_eta(self, s, a=1, **kwargs):
if a != 1:
return self
s = self.args[0]
return dirichlet_eta(s)/(1 - 2**(1 - s))
def _eval_rewrite_as_lerchphi(self, s, a=1, **kwargs):
return lerchphi(1, s, a)
def _eval_is_finite(self):
arg_is_one = (self.args[0] - 1).is_zero
if arg_is_one is not None:
return not arg_is_one
def fdiff(self, argindex=1):
if len(self.args) == 2:
s, a = self.args
else:
s, a = self.args + (1,)
if argindex == 2:
return -s*zeta(s + 1, a)
else:
raise ArgumentIndexError
class dirichlet_eta(Function):
r"""
Dirichlet eta function.
Explanation
===========
For $\operatorname{Re}(s) > 0$, this function is defined as
.. math:: \eta(s) = \sum_{n=1}^\infty \frac{(-1)^{n-1}}{n^s}.
It admits a unique analytic continuation to all of $\mathbb{C}$.
It is an entire, unbranched function.
Examples
========
The Dirichlet eta function is closely related to the Riemann zeta function:
>>> from sympy import dirichlet_eta, zeta
>>> from sympy.abc import s
>>> dirichlet_eta(s).rewrite(zeta)
(1 - 2**(1 - s))*zeta(s)
See Also
========
zeta
References
==========
.. [1] https://en.wikipedia.org/wiki/Dirichlet_eta_function
"""
@classmethod
def eval(cls, s):
if s == 1:
return log(2)
z = zeta(s)
if not z.has(zeta):
return (1 - 2**(1 - s))*z
def _eval_rewrite_as_zeta(self, s, **kwargs):
return (1 - 2**(1 - s)) * zeta(s)
class riemann_xi(Function):
r"""
Riemann Xi function.
Examples
========
The Riemann Xi function is closely related to the Riemann zeta function.
The zeros of Riemann Xi function are precisely the non-trivial zeros
of the zeta function.
>>> from sympy import riemann_xi, zeta
>>> from sympy.abc import s
>>> riemann_xi(s).rewrite(zeta)
s*(s - 1)*gamma(s/2)*zeta(s)/(2*pi**(s/2))
References
==========
.. [1] https://en.wikipedia.org/wiki/Riemann_Xi_function
"""
@classmethod
def eval(cls, s):
from sympy import gamma
z = zeta(s)
if s is S.Zero or s is S.One:
return S.Half
if not isinstance(z, zeta):
return s*(s - 1)*gamma(s/2)*z/(2*pi**(s/2))
def _eval_rewrite_as_zeta(self, s, **kwargs):
from sympy import gamma
return s*(s - 1)*gamma(s/2)*zeta(s)/(2*pi**(s/2))
class stieltjes(Function):
r"""
Represents Stieltjes constants, $\gamma_{k}$ that occur in
Laurent Series expansion of the Riemann zeta function.
Examples
========
>>> from sympy import stieltjes
>>> from sympy.abc import n, m
>>> stieltjes(n)
stieltjes(n)
The zero'th stieltjes constant:
>>> stieltjes(0)
EulerGamma
>>> stieltjes(0, 1)
EulerGamma
For generalized stieltjes constants:
>>> stieltjes(n, m)
stieltjes(n, m)
Constants are only defined for integers >= 0:
>>> stieltjes(-1)
zoo
References
==========
.. [1] https://en.wikipedia.org/wiki/Stieltjes_constants
"""
@classmethod
def eval(cls, n, a=None):
n = sympify(n)
if a is not None:
a = sympify(a)
if a is S.NaN:
return S.NaN
if a.is_Integer and a.is_nonpositive:
return S.ComplexInfinity
if n.is_Number:
if n is S.NaN:
return S.NaN
elif n < 0:
return S.ComplexInfinity
elif not n.is_Integer:
return S.ComplexInfinity
elif n is S.Zero and a in [None, 1]:
return S.EulerGamma
if n.is_extended_negative:
return S.ComplexInfinity
if n.is_zero and a in [None, 1]:
return S.EulerGamma
if n.is_integer == False:
return S.ComplexInfinity
|
393644829563be1abf0b0466b5c9445d8460500eaaac7ebaf73c8566f11fcb1a | from sympy.core import S, sympify, oo, diff
from sympy.core.function import Function, ArgumentIndexError
from sympy.core.logic import fuzzy_not
from sympy.core.relational import Eq
from sympy.functions.elementary.complexes import im
from sympy.functions.elementary.piecewise import Piecewise
from sympy.functions.special.delta_functions import Heaviside
###############################################################################
############################# SINGULARITY FUNCTION ############################
###############################################################################
class SingularityFunction(Function):
r"""
Singularity functions are a class of discontinuous functions.
Explanation
===========
Singularity functions take a variable, an offset, and an exponent as
arguments. These functions are represented using Macaulay brackets as:
SingularityFunction(x, a, n) := <x - a>^n
The singularity function will automatically evaluate to
``Derivative(DiracDelta(x - a), x, -n - 1)`` if ``n < 0``
and ``(x - a)**n*Heaviside(x - a)`` if ``n >= 0``.
Examples
========
>>> from sympy import SingularityFunction, diff, Piecewise, DiracDelta, Heaviside, Symbol
>>> from sympy.abc import x, a, n
>>> SingularityFunction(x, a, n)
SingularityFunction(x, a, n)
>>> y = Symbol('y', positive=True)
>>> n = Symbol('n', nonnegative=True)
>>> SingularityFunction(y, -10, n)
(y + 10)**n
>>> y = Symbol('y', negative=True)
>>> SingularityFunction(y, 10, n)
0
>>> SingularityFunction(x, 4, -1).subs(x, 4)
oo
>>> SingularityFunction(x, 10, -2).subs(x, 10)
oo
>>> SingularityFunction(4, 1, 5)
243
>>> diff(SingularityFunction(x, 1, 5) + SingularityFunction(x, 1, 4), x)
4*SingularityFunction(x, 1, 3) + 5*SingularityFunction(x, 1, 4)
>>> diff(SingularityFunction(x, 4, 0), x, 2)
SingularityFunction(x, 4, -2)
>>> SingularityFunction(x, 4, 5).rewrite(Piecewise)
Piecewise(((x - 4)**5, x - 4 > 0), (0, True))
>>> expr = SingularityFunction(x, a, n)
>>> y = Symbol('y', positive=True)
>>> n = Symbol('n', nonnegative=True)
>>> expr.subs({x: y, a: -10, n: n})
(y + 10)**n
The methods ``rewrite(DiracDelta)``, ``rewrite(Heaviside)``, and
``rewrite('HeavisideDiracDelta')`` returns the same output. One can use any
of these methods according to their choice.
>>> expr = SingularityFunction(x, 4, 5) + SingularityFunction(x, -3, -1) - SingularityFunction(x, 0, -2)
>>> expr.rewrite(Heaviside)
(x - 4)**5*Heaviside(x - 4, 1/2) + DiracDelta(x + 3) - DiracDelta(x, 1)
>>> expr.rewrite(DiracDelta)
(x - 4)**5*Heaviside(x - 4, 1/2) + DiracDelta(x + 3) - DiracDelta(x, 1)
>>> expr.rewrite('HeavisideDiracDelta')
(x - 4)**5*Heaviside(x - 4, 1/2) + DiracDelta(x + 3) - DiracDelta(x, 1)
See Also
========
DiracDelta, Heaviside
References
==========
.. [1] https://en.wikipedia.org/wiki/Singularity_function
"""
is_real = True
def fdiff(self, argindex=1):
"""
Returns the first derivative of a DiracDelta Function.
Explanation
===========
The difference between ``diff()`` and ``fdiff()`` is: ``diff()`` is the
user-level function and ``fdiff()`` is an object method. ``fdiff()`` is
a convenience method available in the ``Function`` class. It returns
the derivative of the function without considering the chain rule.
``diff(function, x)`` calls ``Function._eval_derivative`` which in turn
calls ``fdiff()`` internally to compute the derivative of the function.
"""
if argindex == 1:
x = sympify(self.args[0])
a = sympify(self.args[1])
n = sympify(self.args[2])
if n == 0 or n == -1:
return self.func(x, a, n-1)
elif n.is_positive:
return n*self.func(x, a, n-1)
else:
raise ArgumentIndexError(self, argindex)
@classmethod
def eval(cls, variable, offset, exponent):
"""
Returns a simplified form or a value of Singularity Function depending
on the argument passed by the object.
Explanation
===========
The ``eval()`` method is automatically called when the
``SingularityFunction`` class is about to be instantiated and it
returns either some simplified instance or the unevaluated instance
depending on the argument passed. In other words, ``eval()`` method is
not needed to be called explicitly, it is being called and evaluated
once the object is called.
Examples
========
>>> from sympy import SingularityFunction, Symbol, nan
>>> from sympy.abc import x, a, n
>>> SingularityFunction(x, a, n)
SingularityFunction(x, a, n)
>>> SingularityFunction(5, 3, 2)
4
>>> SingularityFunction(x, a, nan)
nan
>>> SingularityFunction(x, 3, 0).subs(x, 3)
1
>>> SingularityFunction(x, a, n).eval(3, 5, 1)
0
>>> SingularityFunction(x, a, n).eval(4, 1, 5)
243
>>> x = Symbol('x', positive = True)
>>> a = Symbol('a', negative = True)
>>> n = Symbol('n', nonnegative = True)
>>> SingularityFunction(x, a, n)
(-a + x)**n
>>> x = Symbol('x', negative = True)
>>> a = Symbol('a', positive = True)
>>> SingularityFunction(x, a, n)
0
"""
x = sympify(variable)
a = sympify(offset)
n = sympify(exponent)
shift = (x - a)
if fuzzy_not(im(shift).is_zero):
raise ValueError("Singularity Functions are defined only for Real Numbers.")
if fuzzy_not(im(n).is_zero):
raise ValueError("Singularity Functions are not defined for imaginary exponents.")
if shift is S.NaN or n is S.NaN:
return S.NaN
if (n + 2).is_negative:
raise ValueError("Singularity Functions are not defined for exponents less than -2.")
if shift.is_extended_negative:
return S.Zero
if n.is_nonnegative and shift.is_extended_nonnegative:
return (x - a)**n
if n == -1 or n == -2:
if shift.is_negative or shift.is_extended_positive:
return S.Zero
if shift.is_zero:
return S.Infinity
def _eval_rewrite_as_Piecewise(self, *args, **kwargs):
'''
Converts a Singularity Function expression into its Piecewise form.
'''
x = self.args[0]
a = self.args[1]
n = sympify(self.args[2])
if n == -1 or n == -2:
return Piecewise((oo, Eq((x - a), 0)), (0, True))
elif n.is_nonnegative:
return Piecewise(((x - a)**n, (x - a) > 0), (0, True))
def _eval_rewrite_as_Heaviside(self, *args, **kwargs):
'''
Rewrites a Singularity Function expression using Heavisides and DiracDeltas.
'''
x = self.args[0]
a = self.args[1]
n = sympify(self.args[2])
if n == -2:
return diff(Heaviside(x - a), x.free_symbols.pop(), 2)
if n == -1:
return diff(Heaviside(x - a), x.free_symbols.pop(), 1)
if n.is_nonnegative:
return (x - a)**n*Heaviside(x - a)
def _eval_as_leading_term(self, x, logx=None, cdir=0):
z, a, n = self.args
shift = (z - a).subs(x, 0)
if n < 0:
return S.Zero
elif n.is_zero and shift.is_zero:
return S.Zero if cdir == -1 else S.One
elif shift.is_positive:
return shift**n
return S.Zero
def _eval_nseries(self, x, n, logx=None, cdir=0):
z, a, n = self.args
shift = (z - a).subs(x, 0)
if n < 0:
return S.Zero
elif n.is_zero and shift.is_zero:
return S.Zero if cdir == -1 else S.One
elif shift.is_positive:
return ((z - a)**n)._eval_nseries(x, n, logx=logx, cdir=cdir)
return S.Zero
_eval_rewrite_as_DiracDelta = _eval_rewrite_as_Heaviside
_eval_rewrite_as_HeavisideDiracDelta = _eval_rewrite_as_Heaviside
|
136d105dd8e2699139c3b0cbc731e1acf76bc9d3bb2a90859d12fcb47b3692f0 | from functools import wraps
from sympy import Add, S, pi, I, Rational, Wild, cacheit, sympify
from sympy.core.function import Function, ArgumentIndexError, _mexpand
from sympy.core.logic import fuzzy_or, fuzzy_not
from sympy.core.power import Pow
from sympy.functions.combinatorial.factorials import factorial
from sympy.functions.elementary.trigonometric import sin, cos, csc, cot
from sympy.functions.elementary.integers import ceiling
from sympy.functions.elementary.complexes import Abs
from sympy.functions.elementary.exponential import exp, log
from sympy.functions.elementary.miscellaneous import sqrt, root
from sympy.functions.elementary.complexes import re, im
from sympy.functions.special.gamma_functions import gamma, digamma
from sympy.functions.special.hyper import hyper
from sympy.polys.orthopolys import spherical_bessel_fn as fn
# TODO
# o Scorer functions G1 and G2
# o Asymptotic expansions
# These are possible, e.g. for fixed order, but since the bessel type
# functions are oscillatory they are not actually tractable at
# infinity, so this is not particularly useful right now.
# o Nicer series expansions.
# o More rewriting.
# o Add solvers to ode.py (or rather add solvers for the hypergeometric equation).
class BesselBase(Function):
"""
Abstract base class for Bessel-type functions.
This class is meant to reduce code duplication.
All Bessel-type functions can 1) be differentiated, with the derivatives
expressed in terms of similar functions, and 2) be rewritten in terms
of other Bessel-type functions.
Here, Bessel-type functions are assumed to have one complex parameter.
To use this base class, define class attributes ``_a`` and ``_b`` such that
``2*F_n' = -_a*F_{n+1} + b*F_{n-1}``.
"""
@property
def order(self):
""" The order of the Bessel-type function. """
return self.args[0]
@property
def argument(self):
""" The argument of the Bessel-type function. """
return self.args[1]
@classmethod
def eval(cls, nu, z):
return
def fdiff(self, argindex=2):
if argindex != 2:
raise ArgumentIndexError(self, argindex)
return (self._b/2 * self.__class__(self.order - 1, self.argument) -
self._a/2 * self.__class__(self.order + 1, self.argument))
def _eval_conjugate(self):
z = self.argument
if z.is_extended_negative is False:
return self.__class__(self.order.conjugate(), z.conjugate())
def _eval_is_meromorphic(self, x, a):
nu, z = self.order, self.argument
if nu.has(x):
return False
if not z._eval_is_meromorphic(x, a):
return None
z0 = z.subs(x, a)
if nu.is_integer:
if isinstance(self, (besselj, besseli, hn1, hn2, jn, yn)) or not nu.is_zero:
return fuzzy_not(z0.is_infinite)
return fuzzy_not(fuzzy_or([z0.is_zero, z0.is_infinite]))
def _eval_expand_func(self, **hints):
nu, z, f = self.order, self.argument, self.__class__
if nu.is_real:
if (nu - 1).is_positive:
return (-self._a*self._b*f(nu - 2, z)._eval_expand_func() +
2*self._a*(nu - 1)*f(nu - 1, z)._eval_expand_func()/z)
elif (nu + 1).is_negative:
return (2*self._b*(nu + 1)*f(nu + 1, z)._eval_expand_func()/z -
self._a*self._b*f(nu + 2, z)._eval_expand_func())
return self
def _eval_simplify(self, **kwargs):
from sympy.simplify.simplify import besselsimp
return besselsimp(self)
class besselj(BesselBase):
r"""
Bessel function of the first kind.
Explanation
===========
The Bessel $J$ function of order $\nu$ is defined to be the function
satisfying Bessel's differential equation
.. math ::
z^2 \frac{\mathrm{d}^2 w}{\mathrm{d}z^2}
+ z \frac{\mathrm{d}w}{\mathrm{d}z} + (z^2 - \nu^2) w = 0,
with Laurent expansion
.. math ::
J_\nu(z) = z^\nu \left(\frac{1}{\Gamma(\nu + 1) 2^\nu} + O(z^2) \right),
if $\nu$ is not a negative integer. If $\nu=-n \in \mathbb{Z}_{<0}$
*is* a negative integer, then the definition is
.. math ::
J_{-n}(z) = (-1)^n J_n(z).
Examples
========
Create a Bessel function object:
>>> from sympy import besselj, jn
>>> from sympy.abc import z, n
>>> b = besselj(n, z)
Differentiate it:
>>> b.diff(z)
besselj(n - 1, z)/2 - besselj(n + 1, z)/2
Rewrite in terms of spherical Bessel functions:
>>> b.rewrite(jn)
sqrt(2)*sqrt(z)*jn(n - 1/2, z)/sqrt(pi)
Access the parameter and argument:
>>> b.order
n
>>> b.argument
z
See Also
========
bessely, besseli, besselk
References
==========
.. [1] Abramowitz, Milton; Stegun, Irene A., eds. (1965), "Chapter 9",
Handbook of Mathematical Functions with Formulas, Graphs, and
Mathematical Tables
.. [2] Luke, Y. L. (1969), The Special Functions and Their
Approximations, Volume 1
.. [3] https://en.wikipedia.org/wiki/Bessel_function
.. [4] http://functions.wolfram.com/Bessel-TypeFunctions/BesselJ/
"""
_a = S.One
_b = S.One
@classmethod
def eval(cls, nu, z):
if z.is_zero:
if nu.is_zero:
return S.One
elif (nu.is_integer and nu.is_zero is False) or re(nu).is_positive:
return S.Zero
elif re(nu).is_negative and not (nu.is_integer is True):
return S.ComplexInfinity
elif nu.is_imaginary:
return S.NaN
if z is S.Infinity or (z is S.NegativeInfinity):
return S.Zero
if z.could_extract_minus_sign():
return (z)**nu*(-z)**(-nu)*besselj(nu, -z)
if nu.is_integer:
if nu.could_extract_minus_sign():
return S.NegativeOne**(-nu)*besselj(-nu, z)
newz = z.extract_multiplicatively(I)
if newz: # NOTE we don't want to change the function if z==0
return I**(nu)*besseli(nu, newz)
# branch handling:
from sympy import unpolarify
if nu.is_integer:
newz = unpolarify(z)
if newz != z:
return besselj(nu, newz)
else:
newz, n = z.extract_branch_factor()
if n != 0:
return exp(2*n*pi*nu*I)*besselj(nu, newz)
nnu = unpolarify(nu)
if nu != nnu:
return besselj(nnu, z)
def _eval_rewrite_as_besseli(self, nu, z, **kwargs):
from sympy import polar_lift
return exp(I*pi*nu/2)*besseli(nu, polar_lift(-I)*z)
def _eval_rewrite_as_bessely(self, nu, z, **kwargs):
if nu.is_integer is False:
return csc(pi*nu)*bessely(-nu, z) - cot(pi*nu)*bessely(nu, z)
def _eval_rewrite_as_jn(self, nu, z, **kwargs):
return sqrt(2*z/pi)*jn(nu - S.Half, self.argument)
def _eval_as_leading_term(self, x, logx=None, cdir=0):
nu, z = self.args
arg = z.as_leading_term(x)
if x in arg.free_symbols:
return arg**nu/(2**nu*gamma(nu + 1))
else:
return self.func(nu, z.subs(x, 0))
def _eval_is_extended_real(self):
nu, z = self.args
if nu.is_integer and z.is_extended_real:
return True
def _eval_nseries(self, x, n, logx, cdir=0):
from sympy.series.order import Order
nu, z = self.args
# In case of powers less than 1, number of terms need to be computed
# separately to avoid repeated callings of _eval_nseries with wrong n
try:
_, exp = z.leadterm(x)
except (ValueError, NotImplementedError):
return self
if exp.is_positive:
newn = ceiling(n/exp)
o = Order(x**n, x)
r = (z/2)._eval_nseries(x, n, logx, cdir).removeO()
if r is S.Zero:
return o
t = (_mexpand(r**2) + o).removeO()
term = r**nu/gamma(nu + 1)
s = [term]
for k in range(1, (newn + 1)//2):
term *= -t/(k*(nu + k))
term = (_mexpand(term) + o).removeO()
s.append(term)
return Add(*s) + o
return super(besselj, self)._eval_nseries(x, n, logx, cdir)
def _sage_(self):
import sage.all as sage
return sage.bessel_J(self.args[0]._sage_(), self.args[1]._sage_())
class bessely(BesselBase):
r"""
Bessel function of the second kind.
Explanation
===========
The Bessel $Y$ function of order $\nu$ is defined as
.. math ::
Y_\nu(z) = \lim_{\mu \to \nu} \frac{J_\mu(z) \cos(\pi \mu)
- J_{-\mu}(z)}{\sin(\pi \mu)},
where $J_\mu(z)$ is the Bessel function of the first kind.
It is a solution to Bessel's equation, and linearly independent from
$J_\nu$.
Examples
========
>>> from sympy import bessely, yn
>>> from sympy.abc import z, n
>>> b = bessely(n, z)
>>> b.diff(z)
bessely(n - 1, z)/2 - bessely(n + 1, z)/2
>>> b.rewrite(yn)
sqrt(2)*sqrt(z)*yn(n - 1/2, z)/sqrt(pi)
See Also
========
besselj, besseli, besselk
References
==========
.. [1] http://functions.wolfram.com/Bessel-TypeFunctions/BesselY/
"""
_a = S.One
_b = S.One
@classmethod
def eval(cls, nu, z):
if z.is_zero:
if nu.is_zero:
return S.NegativeInfinity
elif re(nu).is_zero is False:
return S.ComplexInfinity
elif re(nu).is_zero:
return S.NaN
if z is S.Infinity or z is S.NegativeInfinity:
return S.Zero
if nu.is_integer:
if nu.could_extract_minus_sign():
return S.NegativeOne**(-nu)*bessely(-nu, z)
def _eval_rewrite_as_besselj(self, nu, z, **kwargs):
if nu.is_integer is False:
return csc(pi*nu)*(cos(pi*nu)*besselj(nu, z) - besselj(-nu, z))
def _eval_rewrite_as_besseli(self, nu, z, **kwargs):
aj = self._eval_rewrite_as_besselj(*self.args)
if aj:
return aj.rewrite(besseli)
def _eval_rewrite_as_yn(self, nu, z, **kwargs):
return sqrt(2*z/pi) * yn(nu - S.Half, self.argument)
def _eval_as_leading_term(self, x, logx=None, cdir=0):
nu, z = self.args
term_one = ((2/pi)*log(z/2)*besselj(nu, z))
term_two = (z/2)**(-nu)*factorial(nu - 1)/pi if (nu - 1).is_positive else S.Zero
term_three = (z/2)**nu/(pi*factorial(nu))*(digamma(nu + 1) - S.EulerGamma)
arg = Add(*[term_one, term_two, term_three]).as_leading_term(x)
if x in arg.free_symbols:
return arg
else:
return self.func(nu, z.subs(x, 0).cancel())
def _eval_is_extended_real(self):
nu, z = self.args
if nu.is_integer and z.is_positive:
return True
def _eval_nseries(self, x, n, logx, cdir=0):
from sympy.series.order import Order
nu, z = self.args
# In case of powers less than 1, number of terms need to be computed
# separately to avoid repeated callings of _eval_nseries with wrong n
try:
_, exp = z.leadterm(x)
except (ValueError, NotImplementedError):
return self
if exp.is_positive and nu.is_integer:
newn = ceiling(n/exp)
bn = besselj(nu, z)
a = ((2/pi)*log(z/2)*bn)._eval_nseries(x, n, logx, cdir)
b, c = [], []
o = Order(x**n, x)
r = (z/2)._eval_nseries(x, n, logx, cdir).removeO()
if r is S.Zero:
return o
t = (_mexpand(r**2) + o).removeO()
if nu > S.One:
term = r**(-nu)*factorial(nu - 1)/pi
b.append(term)
for k in range(1, nu - 1):
term *= t*(nu - k - 1)/k
term = (_mexpand(term) + o).removeO()
b.append(term)
p = r**nu/(pi*factorial(nu))
term = p*(digamma(nu + 1) - S.EulerGamma)
c.append(term)
for k in range(1, (newn + 1)//2):
p *= -t/(k*(k + nu))
p = (_mexpand(p) + o).removeO()
term = p*(digamma(k + nu + 1) + digamma(k + 1))
c.append(term)
return a - Add(*b) - Add(*c) # Order term comes from a
return super(bessely, self)._eval_nseries(x, n, logx, cdir)
def _sage_(self):
import sage.all as sage
return sage.bessel_Y(self.args[0]._sage_(), self.args[1]._sage_())
class besseli(BesselBase):
r"""
Modified Bessel function of the first kind.
Explanation
===========
The Bessel $I$ function is a solution to the modified Bessel equation
.. math ::
z^2 \frac{\mathrm{d}^2 w}{\mathrm{d}z^2}
+ z \frac{\mathrm{d}w}{\mathrm{d}z} + (z^2 + \nu^2)^2 w = 0.
It can be defined as
.. math ::
I_\nu(z) = i^{-\nu} J_\nu(iz),
where $J_\nu(z)$ is the Bessel function of the first kind.
Examples
========
>>> from sympy import besseli
>>> from sympy.abc import z, n
>>> besseli(n, z).diff(z)
besseli(n - 1, z)/2 + besseli(n + 1, z)/2
See Also
========
besselj, bessely, besselk
References
==========
.. [1] http://functions.wolfram.com/Bessel-TypeFunctions/BesselI/
"""
_a = -S.One
_b = S.One
@classmethod
def eval(cls, nu, z):
if z.is_zero:
if nu.is_zero:
return S.One
elif (nu.is_integer and nu.is_zero is False) or re(nu).is_positive:
return S.Zero
elif re(nu).is_negative and not (nu.is_integer is True):
return S.ComplexInfinity
elif nu.is_imaginary:
return S.NaN
if im(z) is S.Infinity or im(z) is S.NegativeInfinity:
return S.Zero
if z.could_extract_minus_sign():
return (z)**nu*(-z)**(-nu)*besseli(nu, -z)
if nu.is_integer:
if nu.could_extract_minus_sign():
return besseli(-nu, z)
newz = z.extract_multiplicatively(I)
if newz: # NOTE we don't want to change the function if z==0
return I**(-nu)*besselj(nu, -newz)
# branch handling:
from sympy import unpolarify
if nu.is_integer:
newz = unpolarify(z)
if newz != z:
return besseli(nu, newz)
else:
newz, n = z.extract_branch_factor()
if n != 0:
return exp(2*n*pi*nu*I)*besseli(nu, newz)
nnu = unpolarify(nu)
if nu != nnu:
return besseli(nnu, z)
def _eval_rewrite_as_besselj(self, nu, z, **kwargs):
from sympy import polar_lift
return exp(-I*pi*nu/2)*besselj(nu, polar_lift(I)*z)
def _eval_rewrite_as_bessely(self, nu, z, **kwargs):
aj = self._eval_rewrite_as_besselj(*self.args)
if aj:
return aj.rewrite(bessely)
def _eval_rewrite_as_jn(self, nu, z, **kwargs):
return self._eval_rewrite_as_besselj(*self.args).rewrite(jn)
def _eval_is_extended_real(self):
nu, z = self.args
if nu.is_integer and z.is_extended_real:
return True
def _sage_(self):
import sage.all as sage
return sage.bessel_I(self.args[0]._sage_(), self.args[1]._sage_())
class besselk(BesselBase):
r"""
Modified Bessel function of the second kind.
Explanation
===========
The Bessel $K$ function of order $\nu$ is defined as
.. math ::
K_\nu(z) = \lim_{\mu \to \nu} \frac{\pi}{2}
\frac{I_{-\mu}(z) -I_\mu(z)}{\sin(\pi \mu)},
where $I_\mu(z)$ is the modified Bessel function of the first kind.
It is a solution of the modified Bessel equation, and linearly independent
from $Y_\nu$.
Examples
========
>>> from sympy import besselk
>>> from sympy.abc import z, n
>>> besselk(n, z).diff(z)
-besselk(n - 1, z)/2 - besselk(n + 1, z)/2
See Also
========
besselj, besseli, bessely
References
==========
.. [1] http://functions.wolfram.com/Bessel-TypeFunctions/BesselK/
"""
_a = S.One
_b = -S.One
@classmethod
def eval(cls, nu, z):
if z.is_zero:
if nu.is_zero:
return S.Infinity
elif re(nu).is_zero is False:
return S.ComplexInfinity
elif re(nu).is_zero:
return S.NaN
if z in (S.Infinity, I*S.Infinity, I*S.NegativeInfinity):
return S.Zero
if nu.is_integer:
if nu.could_extract_minus_sign():
return besselk(-nu, z)
def _eval_rewrite_as_besseli(self, nu, z, **kwargs):
if nu.is_integer is False:
return pi*csc(pi*nu)*(besseli(-nu, z) - besseli(nu, z))/2
def _eval_rewrite_as_besselj(self, nu, z, **kwargs):
ai = self._eval_rewrite_as_besseli(*self.args)
if ai:
return ai.rewrite(besselj)
def _eval_rewrite_as_bessely(self, nu, z, **kwargs):
aj = self._eval_rewrite_as_besselj(*self.args)
if aj:
return aj.rewrite(bessely)
def _eval_rewrite_as_yn(self, nu, z, **kwargs):
ay = self._eval_rewrite_as_bessely(*self.args)
if ay:
return ay.rewrite(yn)
def _eval_is_extended_real(self):
nu, z = self.args
if nu.is_integer and z.is_positive:
return True
def _sage_(self):
import sage.all as sage
return sage.bessel_K(self.args[0]._sage_(), self.args[1]._sage_())
class hankel1(BesselBase):
r"""
Hankel function of the first kind.
Explanation
===========
This function is defined as
.. math ::
H_\nu^{(1)} = J_\nu(z) + iY_\nu(z),
where $J_\nu(z)$ is the Bessel function of the first kind, and
$Y_\nu(z)$ is the Bessel function of the second kind.
It is a solution to Bessel's equation.
Examples
========
>>> from sympy import hankel1
>>> from sympy.abc import z, n
>>> hankel1(n, z).diff(z)
hankel1(n - 1, z)/2 - hankel1(n + 1, z)/2
See Also
========
hankel2, besselj, bessely
References
==========
.. [1] http://functions.wolfram.com/Bessel-TypeFunctions/HankelH1/
"""
_a = S.One
_b = S.One
def _eval_conjugate(self):
z = self.argument
if z.is_extended_negative is False:
return hankel2(self.order.conjugate(), z.conjugate())
class hankel2(BesselBase):
r"""
Hankel function of the second kind.
Explanation
===========
This function is defined as
.. math ::
H_\nu^{(2)} = J_\nu(z) - iY_\nu(z),
where $J_\nu(z)$ is the Bessel function of the first kind, and
$Y_\nu(z)$ is the Bessel function of the second kind.
It is a solution to Bessel's equation, and linearly independent from
$H_\nu^{(1)}$.
Examples
========
>>> from sympy import hankel2
>>> from sympy.abc import z, n
>>> hankel2(n, z).diff(z)
hankel2(n - 1, z)/2 - hankel2(n + 1, z)/2
See Also
========
hankel1, besselj, bessely
References
==========
.. [1] http://functions.wolfram.com/Bessel-TypeFunctions/HankelH2/
"""
_a = S.One
_b = S.One
def _eval_conjugate(self):
z = self.argument
if z.is_extended_negative is False:
return hankel1(self.order.conjugate(), z.conjugate())
def assume_integer_order(fn):
@wraps(fn)
def g(self, nu, z):
if nu.is_integer:
return fn(self, nu, z)
return g
class SphericalBesselBase(BesselBase):
"""
Base class for spherical Bessel functions.
These are thin wrappers around ordinary Bessel functions,
since spherical Bessel functions differ from the ordinary
ones just by a slight change in order.
To use this class, define the ``_eval_evalf()`` and ``_expand()`` methods.
"""
def _expand(self, **hints):
""" Expand self into a polynomial. Nu is guaranteed to be Integer. """
raise NotImplementedError('expansion')
def _eval_expand_func(self, **hints):
if self.order.is_Integer:
return self._expand(**hints)
return self
def fdiff(self, argindex=2):
if argindex != 2:
raise ArgumentIndexError(self, argindex)
return self.__class__(self.order - 1, self.argument) - \
self * (self.order + 1)/self.argument
def _jn(n, z):
return fn(n, z)*sin(z) + (-1)**(n + 1)*fn(-n - 1, z)*cos(z)
def _yn(n, z):
# (-1)**(n + 1) * _jn(-n - 1, z)
return (-1)**(n + 1) * fn(-n - 1, z)*sin(z) - fn(n, z)*cos(z)
class jn(SphericalBesselBase):
r"""
Spherical Bessel function of the first kind.
Explanation
===========
This function is a solution to the spherical Bessel equation
.. math ::
z^2 \frac{\mathrm{d}^2 w}{\mathrm{d}z^2}
+ 2z \frac{\mathrm{d}w}{\mathrm{d}z} + (z^2 - \nu(\nu + 1)) w = 0.
It can be defined as
.. math ::
j_\nu(z) = \sqrt{\frac{\pi}{2z}} J_{\nu + \frac{1}{2}}(z),
where $J_\nu(z)$ is the Bessel function of the first kind.
The spherical Bessel functions of integral order are
calculated using the formula:
.. math:: j_n(z) = f_n(z) \sin{z} + (-1)^{n+1} f_{-n-1}(z) \cos{z},
where the coefficients $f_n(z)$ are available as
:func:`sympy.polys.orthopolys.spherical_bessel_fn`.
Examples
========
>>> from sympy import Symbol, jn, sin, cos, expand_func, besselj, bessely
>>> z = Symbol("z")
>>> nu = Symbol("nu", integer=True)
>>> print(expand_func(jn(0, z)))
sin(z)/z
>>> expand_func(jn(1, z)) == sin(z)/z**2 - cos(z)/z
True
>>> expand_func(jn(3, z))
(-6/z**2 + 15/z**4)*sin(z) + (1/z - 15/z**3)*cos(z)
>>> jn(nu, z).rewrite(besselj)
sqrt(2)*sqrt(pi)*sqrt(1/z)*besselj(nu + 1/2, z)/2
>>> jn(nu, z).rewrite(bessely)
(-1)**nu*sqrt(2)*sqrt(pi)*sqrt(1/z)*bessely(-nu - 1/2, z)/2
>>> jn(2, 5.2+0.3j).evalf(20)
0.099419756723640344491 - 0.054525080242173562897*I
See Also
========
besselj, bessely, besselk, yn
References
==========
.. [1] http://dlmf.nist.gov/10.47
"""
@classmethod
def eval(cls, nu, z):
if z.is_zero:
if nu.is_zero:
return S.One
elif nu.is_integer:
if nu.is_positive:
return S.Zero
else:
return S.ComplexInfinity
if z in (S.NegativeInfinity, S.Infinity):
return S.Zero
def _eval_rewrite_as_besselj(self, nu, z, **kwargs):
return sqrt(pi/(2*z)) * besselj(nu + S.Half, z)
def _eval_rewrite_as_bessely(self, nu, z, **kwargs):
return (-1)**nu * sqrt(pi/(2*z)) * bessely(-nu - S.Half, z)
def _eval_rewrite_as_yn(self, nu, z, **kwargs):
return (-1)**(nu) * yn(-nu - 1, z)
def _expand(self, **hints):
return _jn(self.order, self.argument)
def _eval_evalf(self, prec):
if self.order.is_Integer:
return self.rewrite(besselj)._eval_evalf(prec)
class yn(SphericalBesselBase):
r"""
Spherical Bessel function of the second kind.
Explanation
===========
This function is another solution to the spherical Bessel equation, and
linearly independent from $j_n$. It can be defined as
.. math ::
y_\nu(z) = \sqrt{\frac{\pi}{2z}} Y_{\nu + \frac{1}{2}}(z),
where $Y_\nu(z)$ is the Bessel function of the second kind.
For integral orders $n$, $y_n$ is calculated using the formula:
.. math:: y_n(z) = (-1)^{n+1} j_{-n-1}(z)
Examples
========
>>> from sympy import Symbol, yn, sin, cos, expand_func, besselj, bessely
>>> z = Symbol("z")
>>> nu = Symbol("nu", integer=True)
>>> print(expand_func(yn(0, z)))
-cos(z)/z
>>> expand_func(yn(1, z)) == -cos(z)/z**2-sin(z)/z
True
>>> yn(nu, z).rewrite(besselj)
(-1)**(nu + 1)*sqrt(2)*sqrt(pi)*sqrt(1/z)*besselj(-nu - 1/2, z)/2
>>> yn(nu, z).rewrite(bessely)
sqrt(2)*sqrt(pi)*sqrt(1/z)*bessely(nu + 1/2, z)/2
>>> yn(2, 5.2+0.3j).evalf(20)
0.18525034196069722536 + 0.014895573969924817587*I
See Also
========
besselj, bessely, besselk, jn
References
==========
.. [1] http://dlmf.nist.gov/10.47
"""
@assume_integer_order
def _eval_rewrite_as_besselj(self, nu, z, **kwargs):
return (-1)**(nu+1) * sqrt(pi/(2*z)) * besselj(-nu - S.Half, z)
@assume_integer_order
def _eval_rewrite_as_bessely(self, nu, z, **kwargs):
return sqrt(pi/(2*z)) * bessely(nu + S.Half, z)
def _eval_rewrite_as_jn(self, nu, z, **kwargs):
return (-1)**(nu + 1) * jn(-nu - 1, z)
def _expand(self, **hints):
return _yn(self.order, self.argument)
def _eval_evalf(self, prec):
if self.order.is_Integer:
return self.rewrite(bessely)._eval_evalf(prec)
class SphericalHankelBase(SphericalBesselBase):
@assume_integer_order
def _eval_rewrite_as_besselj(self, nu, z, **kwargs):
# jn +- I*yn
# jn as beeselj: sqrt(pi/(2*z)) * besselj(nu + S.Half, z)
# yn as besselj: (-1)**(nu+1) * sqrt(pi/(2*z)) * besselj(-nu - S.Half, z)
hks = self._hankel_kind_sign
return sqrt(pi/(2*z))*(besselj(nu + S.Half, z) +
hks*I*(-1)**(nu+1)*besselj(-nu - S.Half, z))
@assume_integer_order
def _eval_rewrite_as_bessely(self, nu, z, **kwargs):
# jn +- I*yn
# jn as bessely: (-1)**nu * sqrt(pi/(2*z)) * bessely(-nu - S.Half, z)
# yn as bessely: sqrt(pi/(2*z)) * bessely(nu + S.Half, z)
hks = self._hankel_kind_sign
return sqrt(pi/(2*z))*((-1)**nu*bessely(-nu - S.Half, z) +
hks*I*bessely(nu + S.Half, z))
def _eval_rewrite_as_yn(self, nu, z, **kwargs):
hks = self._hankel_kind_sign
return jn(nu, z).rewrite(yn) + hks*I*yn(nu, z)
def _eval_rewrite_as_jn(self, nu, z, **kwargs):
hks = self._hankel_kind_sign
return jn(nu, z) + hks*I*yn(nu, z).rewrite(jn)
def _eval_expand_func(self, **hints):
if self.order.is_Integer:
return self._expand(**hints)
else:
nu = self.order
z = self.argument
hks = self._hankel_kind_sign
return jn(nu, z) + hks*I*yn(nu, z)
def _expand(self, **hints):
n = self.order
z = self.argument
hks = self._hankel_kind_sign
# fully expanded version
# return ((fn(n, z) * sin(z) +
# (-1)**(n + 1) * fn(-n - 1, z) * cos(z)) + # jn
# (hks * I * (-1)**(n + 1) *
# (fn(-n - 1, z) * hk * I * sin(z) +
# (-1)**(-n) * fn(n, z) * I * cos(z))) # +-I*yn
# )
return (_jn(n, z) + hks*I*_yn(n, z)).expand()
def _eval_evalf(self, prec):
if self.order.is_Integer:
return self.rewrite(besselj)._eval_evalf(prec)
class hn1(SphericalHankelBase):
r"""
Spherical Hankel function of the first kind.
Explanation
===========
This function is defined as
.. math:: h_\nu^(1)(z) = j_\nu(z) + i y_\nu(z),
where $j_\nu(z)$ and $y_\nu(z)$ are the spherical
Bessel function of the first and second kinds.
For integral orders $n$, $h_n^(1)$ is calculated using the formula:
.. math:: h_n^(1)(z) = j_{n}(z) + i (-1)^{n+1} j_{-n-1}(z)
Examples
========
>>> from sympy import Symbol, hn1, hankel1, expand_func, yn, jn
>>> z = Symbol("z")
>>> nu = Symbol("nu", integer=True)
>>> print(expand_func(hn1(nu, z)))
jn(nu, z) + I*yn(nu, z)
>>> print(expand_func(hn1(0, z)))
sin(z)/z - I*cos(z)/z
>>> print(expand_func(hn1(1, z)))
-I*sin(z)/z - cos(z)/z + sin(z)/z**2 - I*cos(z)/z**2
>>> hn1(nu, z).rewrite(jn)
(-1)**(nu + 1)*I*jn(-nu - 1, z) + jn(nu, z)
>>> hn1(nu, z).rewrite(yn)
(-1)**nu*yn(-nu - 1, z) + I*yn(nu, z)
>>> hn1(nu, z).rewrite(hankel1)
sqrt(2)*sqrt(pi)*sqrt(1/z)*hankel1(nu, z)/2
See Also
========
hn2, jn, yn, hankel1, hankel2
References
==========
.. [1] http://dlmf.nist.gov/10.47
"""
_hankel_kind_sign = S.One
@assume_integer_order
def _eval_rewrite_as_hankel1(self, nu, z, **kwargs):
return sqrt(pi/(2*z))*hankel1(nu, z)
class hn2(SphericalHankelBase):
r"""
Spherical Hankel function of the second kind.
Explanation
===========
This function is defined as
.. math:: h_\nu^(2)(z) = j_\nu(z) - i y_\nu(z),
where $j_\nu(z)$ and $y_\nu(z)$ are the spherical
Bessel function of the first and second kinds.
For integral orders $n$, $h_n^(2)$ is calculated using the formula:
.. math:: h_n^(2)(z) = j_{n} - i (-1)^{n+1} j_{-n-1}(z)
Examples
========
>>> from sympy import Symbol, hn2, hankel2, expand_func, jn, yn
>>> z = Symbol("z")
>>> nu = Symbol("nu", integer=True)
>>> print(expand_func(hn2(nu, z)))
jn(nu, z) - I*yn(nu, z)
>>> print(expand_func(hn2(0, z)))
sin(z)/z + I*cos(z)/z
>>> print(expand_func(hn2(1, z)))
I*sin(z)/z - cos(z)/z + sin(z)/z**2 + I*cos(z)/z**2
>>> hn2(nu, z).rewrite(hankel2)
sqrt(2)*sqrt(pi)*sqrt(1/z)*hankel2(nu, z)/2
>>> hn2(nu, z).rewrite(jn)
-(-1)**(nu + 1)*I*jn(-nu - 1, z) + jn(nu, z)
>>> hn2(nu, z).rewrite(yn)
(-1)**nu*yn(-nu - 1, z) - I*yn(nu, z)
See Also
========
hn1, jn, yn, hankel1, hankel2
References
==========
.. [1] http://dlmf.nist.gov/10.47
"""
_hankel_kind_sign = -S.One
@assume_integer_order
def _eval_rewrite_as_hankel2(self, nu, z, **kwargs):
return sqrt(pi/(2*z))*hankel2(nu, z)
def jn_zeros(n, k, method="sympy", dps=15):
"""
Zeros of the spherical Bessel function of the first kind.
Explanation
===========
This returns an array of zeros of $jn$ up to the $k$-th zero.
* method = "sympy": uses `mpmath.besseljzero
<http://mpmath.org/doc/current/functions/bessel.html#mpmath.besseljzero>`_
* method = "scipy": uses the
`SciPy's sph_jn <http://docs.scipy.org/doc/scipy/reference/generated/scipy.special.jn_zeros.html>`_
and
`newton <http://docs.scipy.org/doc/scipy/reference/generated/scipy.optimize.newton.html>`_
to find all
roots, which is faster than computing the zeros using a general
numerical solver, but it requires SciPy and only works with low
precision floating point numbers. (The function used with
method="sympy" is a recent addition to mpmath; before that a general
solver was used.)
Examples
========
>>> from sympy import jn_zeros
>>> jn_zeros(2, 4, dps=5)
[5.7635, 9.095, 12.323, 15.515]
See Also
========
jn, yn, besselj, besselk, bessely
Parameters
==========
n : integer
order of Bessel function
k : integer
number of zeros to return
"""
from math import pi
if method == "sympy":
from mpmath import besseljzero
from mpmath.libmp.libmpf import dps_to_prec
from sympy import Expr
prec = dps_to_prec(dps)
return [Expr._from_mpmath(besseljzero(S(n + 0.5)._to_mpmath(prec),
int(l)), prec)
for l in range(1, k + 1)]
elif method == "scipy":
from scipy.optimize import newton
try:
from scipy.special import spherical_jn
f = lambda x: spherical_jn(n, x)
except ImportError:
from scipy.special import sph_jn
f = lambda x: sph_jn(n, x)[0][-1]
else:
raise NotImplementedError("Unknown method.")
def solver(f, x):
if method == "scipy":
root = newton(f, x)
else:
raise NotImplementedError("Unknown method.")
return root
# we need to approximate the position of the first root:
root = n + pi
# determine the first root exactly:
root = solver(f, root)
roots = [root]
for i in range(k - 1):
# estimate the position of the next root using the last root + pi:
root = solver(f, root + pi)
roots.append(root)
return roots
class AiryBase(Function):
"""
Abstract base class for Airy functions.
This class is meant to reduce code duplication.
"""
def _eval_conjugate(self):
return self.func(self.args[0].conjugate())
def _eval_is_extended_real(self):
return self.args[0].is_extended_real
def as_real_imag(self, deep=True, **hints):
z = self.args[0]
zc = z.conjugate()
f = self.func
u = (f(z)+f(zc))/2
v = I*(f(zc)-f(z))/2
return u, v
def _eval_expand_complex(self, deep=True, **hints):
re_part, im_part = self.as_real_imag(deep=deep, **hints)
return re_part + im_part*S.ImaginaryUnit
class airyai(AiryBase):
r"""
The Airy function $\operatorname{Ai}$ of the first kind.
Explanation
===========
The Airy function $\operatorname{Ai}(z)$ is defined to be the function
satisfying Airy's differential equation
.. math::
\frac{\mathrm{d}^2 w(z)}{\mathrm{d}z^2} - z w(z) = 0.
Equivalently, for real $z$
.. math::
\operatorname{Ai}(z) := \frac{1}{\pi}
\int_0^\infty \cos\left(\frac{t^3}{3} + z t\right) \mathrm{d}t.
Examples
========
Create an Airy function object:
>>> from sympy import airyai
>>> from sympy.abc import z
>>> airyai(z)
airyai(z)
Several special values are known:
>>> airyai(0)
3**(1/3)/(3*gamma(2/3))
>>> from sympy import oo
>>> airyai(oo)
0
>>> airyai(-oo)
0
The Airy function obeys the mirror symmetry:
>>> from sympy import conjugate
>>> conjugate(airyai(z))
airyai(conjugate(z))
Differentiation with respect to $z$ is supported:
>>> from sympy import diff
>>> diff(airyai(z), z)
airyaiprime(z)
>>> diff(airyai(z), z, 2)
z*airyai(z)
Series expansion is also supported:
>>> from sympy import series
>>> series(airyai(z), z, 0, 3)
3**(5/6)*gamma(1/3)/(6*pi) - 3**(1/6)*z*gamma(2/3)/(2*pi) + O(z**3)
We can numerically evaluate the Airy function to arbitrary precision
on the whole complex plane:
>>> airyai(-2).evalf(50)
0.22740742820168557599192443603787379946077222541710
Rewrite $\operatorname{Ai}(z)$ in terms of hypergeometric functions:
>>> from sympy import hyper
>>> airyai(z).rewrite(hyper)
-3**(2/3)*z*hyper((), (4/3,), z**3/9)/(3*gamma(1/3)) + 3**(1/3)*hyper((), (2/3,), z**3/9)/(3*gamma(2/3))
See Also
========
airybi: Airy function of the second kind.
airyaiprime: Derivative of the Airy function of the first kind.
airybiprime: Derivative of the Airy function of the second kind.
References
==========
.. [1] https://en.wikipedia.org/wiki/Airy_function
.. [2] http://dlmf.nist.gov/9
.. [3] http://www.encyclopediaofmath.org/index.php/Airy_functions
.. [4] http://mathworld.wolfram.com/AiryFunctions.html
"""
nargs = 1
unbranched = True
@classmethod
def eval(cls, arg):
if arg.is_Number:
if arg is S.NaN:
return S.NaN
elif arg is S.Infinity:
return S.Zero
elif arg is S.NegativeInfinity:
return S.Zero
elif arg.is_zero:
return S.One / (3**Rational(2, 3) * gamma(Rational(2, 3)))
if arg.is_zero:
return S.One / (3**Rational(2, 3) * gamma(Rational(2, 3)))
def fdiff(self, argindex=1):
if argindex == 1:
return airyaiprime(self.args[0])
else:
raise ArgumentIndexError(self, argindex)
@staticmethod
@cacheit
def taylor_term(n, x, *previous_terms):
if n < 0:
return S.Zero
else:
x = sympify(x)
if len(previous_terms) > 1:
p = previous_terms[-1]
return ((3**Rational(1, 3)*x)**(-n)*(3**Rational(1, 3)*x)**(n + 1)*sin(pi*(n*Rational(2, 3) + Rational(4, 3)))*factorial(n) *
gamma(n/3 + Rational(2, 3))/(sin(pi*(n*Rational(2, 3) + Rational(2, 3)))*factorial(n + 1)*gamma(n/3 + Rational(1, 3))) * p)
else:
return (S.One/(3**Rational(2, 3)*pi) * gamma((n+S.One)/S(3)) * sin(2*pi*(n+S.One)/S(3)) /
factorial(n) * (root(3, 3)*x)**n)
def _eval_rewrite_as_besselj(self, z, **kwargs):
ot = Rational(1, 3)
tt = Rational(2, 3)
a = Pow(-z, Rational(3, 2))
if re(z).is_negative:
return ot*sqrt(-z) * (besselj(-ot, tt*a) + besselj(ot, tt*a))
def _eval_rewrite_as_besseli(self, z, **kwargs):
ot = Rational(1, 3)
tt = Rational(2, 3)
a = Pow(z, Rational(3, 2))
if re(z).is_positive:
return ot*sqrt(z) * (besseli(-ot, tt*a) - besseli(ot, tt*a))
else:
return ot*(Pow(a, ot)*besseli(-ot, tt*a) - z*Pow(a, -ot)*besseli(ot, tt*a))
def _eval_rewrite_as_hyper(self, z, **kwargs):
pf1 = S.One / (3**Rational(2, 3)*gamma(Rational(2, 3)))
pf2 = z / (root(3, 3)*gamma(Rational(1, 3)))
return pf1 * hyper([], [Rational(2, 3)], z**3/9) - pf2 * hyper([], [Rational(4, 3)], z**3/9)
def _eval_expand_func(self, **hints):
arg = self.args[0]
symbs = arg.free_symbols
if len(symbs) == 1:
z = symbs.pop()
c = Wild("c", exclude=[z])
d = Wild("d", exclude=[z])
m = Wild("m", exclude=[z])
n = Wild("n", exclude=[z])
M = arg.match(c*(d*z**n)**m)
if M is not None:
m = M[m]
# The transformation is given by 03.05.16.0001.01
# http://functions.wolfram.com/Bessel-TypeFunctions/AiryAi/16/01/01/0001/
if (3*m).is_integer:
c = M[c]
d = M[d]
n = M[n]
pf = (d * z**n)**m / (d**m * z**(m*n))
newarg = c * d**m * z**(m*n)
return S.Half * ((pf + S.One)*airyai(newarg) - (pf - S.One)/sqrt(3)*airybi(newarg))
class airybi(AiryBase):
r"""
The Airy function $\operatorname{Bi}$ of the second kind.
Explanation
===========
The Airy function $\operatorname{Bi}(z)$ is defined to be the function
satisfying Airy's differential equation
.. math::
\frac{\mathrm{d}^2 w(z)}{\mathrm{d}z^2} - z w(z) = 0.
Equivalently, for real $z$
.. math::
\operatorname{Bi}(z) := \frac{1}{\pi}
\int_0^\infty
\exp\left(-\frac{t^3}{3} + z t\right)
+ \sin\left(\frac{t^3}{3} + z t\right) \mathrm{d}t.
Examples
========
Create an Airy function object:
>>> from sympy import airybi
>>> from sympy.abc import z
>>> airybi(z)
airybi(z)
Several special values are known:
>>> airybi(0)
3**(5/6)/(3*gamma(2/3))
>>> from sympy import oo
>>> airybi(oo)
oo
>>> airybi(-oo)
0
The Airy function obeys the mirror symmetry:
>>> from sympy import conjugate
>>> conjugate(airybi(z))
airybi(conjugate(z))
Differentiation with respect to $z$ is supported:
>>> from sympy import diff
>>> diff(airybi(z), z)
airybiprime(z)
>>> diff(airybi(z), z, 2)
z*airybi(z)
Series expansion is also supported:
>>> from sympy import series
>>> series(airybi(z), z, 0, 3)
3**(1/3)*gamma(1/3)/(2*pi) + 3**(2/3)*z*gamma(2/3)/(2*pi) + O(z**3)
We can numerically evaluate the Airy function to arbitrary precision
on the whole complex plane:
>>> airybi(-2).evalf(50)
-0.41230258795639848808323405461146104203453483447240
Rewrite $\operatorname{Bi}(z)$ in terms of hypergeometric functions:
>>> from sympy import hyper
>>> airybi(z).rewrite(hyper)
3**(1/6)*z*hyper((), (4/3,), z**3/9)/gamma(1/3) + 3**(5/6)*hyper((), (2/3,), z**3/9)/(3*gamma(2/3))
See Also
========
airyai: Airy function of the first kind.
airyaiprime: Derivative of the Airy function of the first kind.
airybiprime: Derivative of the Airy function of the second kind.
References
==========
.. [1] https://en.wikipedia.org/wiki/Airy_function
.. [2] http://dlmf.nist.gov/9
.. [3] http://www.encyclopediaofmath.org/index.php/Airy_functions
.. [4] http://mathworld.wolfram.com/AiryFunctions.html
"""
nargs = 1
unbranched = True
@classmethod
def eval(cls, arg):
if arg.is_Number:
if arg is S.NaN:
return S.NaN
elif arg is S.Infinity:
return S.Infinity
elif arg is S.NegativeInfinity:
return S.Zero
elif arg.is_zero:
return S.One / (3**Rational(1, 6) * gamma(Rational(2, 3)))
if arg.is_zero:
return S.One / (3**Rational(1, 6) * gamma(Rational(2, 3)))
def fdiff(self, argindex=1):
if argindex == 1:
return airybiprime(self.args[0])
else:
raise ArgumentIndexError(self, argindex)
@staticmethod
@cacheit
def taylor_term(n, x, *previous_terms):
if n < 0:
return S.Zero
else:
x = sympify(x)
if len(previous_terms) > 1:
p = previous_terms[-1]
return (3**Rational(1, 3)*x * Abs(sin(2*pi*(n + S.One)/S(3))) * factorial((n - S.One)/S(3)) /
((n + S.One) * Abs(cos(2*pi*(n + S.Half)/S(3))) * factorial((n - 2)/S(3))) * p)
else:
return (S.One/(root(3, 6)*pi) * gamma((n + S.One)/S(3)) * Abs(sin(2*pi*(n + S.One)/S(3))) /
factorial(n) * (root(3, 3)*x)**n)
def _eval_rewrite_as_besselj(self, z, **kwargs):
ot = Rational(1, 3)
tt = Rational(2, 3)
a = Pow(-z, Rational(3, 2))
if re(z).is_negative:
return sqrt(-z/3) * (besselj(-ot, tt*a) - besselj(ot, tt*a))
def _eval_rewrite_as_besseli(self, z, **kwargs):
ot = Rational(1, 3)
tt = Rational(2, 3)
a = Pow(z, Rational(3, 2))
if re(z).is_positive:
return sqrt(z)/sqrt(3) * (besseli(-ot, tt*a) + besseli(ot, tt*a))
else:
b = Pow(a, ot)
c = Pow(a, -ot)
return sqrt(ot)*(b*besseli(-ot, tt*a) + z*c*besseli(ot, tt*a))
def _eval_rewrite_as_hyper(self, z, **kwargs):
pf1 = S.One / (root(3, 6)*gamma(Rational(2, 3)))
pf2 = z*root(3, 6) / gamma(Rational(1, 3))
return pf1 * hyper([], [Rational(2, 3)], z**3/9) + pf2 * hyper([], [Rational(4, 3)], z**3/9)
def _eval_expand_func(self, **hints):
arg = self.args[0]
symbs = arg.free_symbols
if len(symbs) == 1:
z = symbs.pop()
c = Wild("c", exclude=[z])
d = Wild("d", exclude=[z])
m = Wild("m", exclude=[z])
n = Wild("n", exclude=[z])
M = arg.match(c*(d*z**n)**m)
if M is not None:
m = M[m]
# The transformation is given by 03.06.16.0001.01
# http://functions.wolfram.com/Bessel-TypeFunctions/AiryBi/16/01/01/0001/
if (3*m).is_integer:
c = M[c]
d = M[d]
n = M[n]
pf = (d * z**n)**m / (d**m * z**(m*n))
newarg = c * d**m * z**(m*n)
return S.Half * (sqrt(3)*(S.One - pf)*airyai(newarg) + (S.One + pf)*airybi(newarg))
class airyaiprime(AiryBase):
r"""
The derivative $\operatorname{Ai}^\prime$ of the Airy function of the first
kind.
Explanation
===========
The Airy function $\operatorname{Ai}^\prime(z)$ is defined to be the
function
.. math::
\operatorname{Ai}^\prime(z) := \frac{\mathrm{d} \operatorname{Ai}(z)}{\mathrm{d} z}.
Examples
========
Create an Airy function object:
>>> from sympy import airyaiprime
>>> from sympy.abc import z
>>> airyaiprime(z)
airyaiprime(z)
Several special values are known:
>>> airyaiprime(0)
-3**(2/3)/(3*gamma(1/3))
>>> from sympy import oo
>>> airyaiprime(oo)
0
The Airy function obeys the mirror symmetry:
>>> from sympy import conjugate
>>> conjugate(airyaiprime(z))
airyaiprime(conjugate(z))
Differentiation with respect to $z$ is supported:
>>> from sympy import diff
>>> diff(airyaiprime(z), z)
z*airyai(z)
>>> diff(airyaiprime(z), z, 2)
z*airyaiprime(z) + airyai(z)
Series expansion is also supported:
>>> from sympy import series
>>> series(airyaiprime(z), z, 0, 3)
-3**(2/3)/(3*gamma(1/3)) + 3**(1/3)*z**2/(6*gamma(2/3)) + O(z**3)
We can numerically evaluate the Airy function to arbitrary precision
on the whole complex plane:
>>> airyaiprime(-2).evalf(50)
0.61825902074169104140626429133247528291577794512415
Rewrite $\operatorname{Ai}^\prime(z)$ in terms of hypergeometric functions:
>>> from sympy import hyper
>>> airyaiprime(z).rewrite(hyper)
3**(1/3)*z**2*hyper((), (5/3,), z**3/9)/(6*gamma(2/3)) - 3**(2/3)*hyper((), (1/3,), z**3/9)/(3*gamma(1/3))
See Also
========
airyai: Airy function of the first kind.
airybi: Airy function of the second kind.
airybiprime: Derivative of the Airy function of the second kind.
References
==========
.. [1] https://en.wikipedia.org/wiki/Airy_function
.. [2] http://dlmf.nist.gov/9
.. [3] http://www.encyclopediaofmath.org/index.php/Airy_functions
.. [4] http://mathworld.wolfram.com/AiryFunctions.html
"""
nargs = 1
unbranched = True
@classmethod
def eval(cls, arg):
if arg.is_Number:
if arg is S.NaN:
return S.NaN
elif arg is S.Infinity:
return S.Zero
if arg.is_zero:
return S.NegativeOne / (3**Rational(1, 3) * gamma(Rational(1, 3)))
def fdiff(self, argindex=1):
if argindex == 1:
return self.args[0]*airyai(self.args[0])
else:
raise ArgumentIndexError(self, argindex)
def _eval_evalf(self, prec):
from mpmath import mp, workprec
from sympy import Expr
z = self.args[0]._to_mpmath(prec)
with workprec(prec):
res = mp.airyai(z, derivative=1)
return Expr._from_mpmath(res, prec)
def _eval_rewrite_as_besselj(self, z, **kwargs):
tt = Rational(2, 3)
a = Pow(-z, Rational(3, 2))
if re(z).is_negative:
return z/3 * (besselj(-tt, tt*a) - besselj(tt, tt*a))
def _eval_rewrite_as_besseli(self, z, **kwargs):
ot = Rational(1, 3)
tt = Rational(2, 3)
a = tt * Pow(z, Rational(3, 2))
if re(z).is_positive:
return z/3 * (besseli(tt, a) - besseli(-tt, a))
else:
a = Pow(z, Rational(3, 2))
b = Pow(a, tt)
c = Pow(a, -tt)
return ot * (z**2*c*besseli(tt, tt*a) - b*besseli(-ot, tt*a))
def _eval_rewrite_as_hyper(self, z, **kwargs):
pf1 = z**2 / (2*3**Rational(2, 3)*gamma(Rational(2, 3)))
pf2 = 1 / (root(3, 3)*gamma(Rational(1, 3)))
return pf1 * hyper([], [Rational(5, 3)], z**3/9) - pf2 * hyper([], [Rational(1, 3)], z**3/9)
def _eval_expand_func(self, **hints):
arg = self.args[0]
symbs = arg.free_symbols
if len(symbs) == 1:
z = symbs.pop()
c = Wild("c", exclude=[z])
d = Wild("d", exclude=[z])
m = Wild("m", exclude=[z])
n = Wild("n", exclude=[z])
M = arg.match(c*(d*z**n)**m)
if M is not None:
m = M[m]
# The transformation is in principle
# given by 03.07.16.0001.01 but note
# that there is an error in this formula.
# http://functions.wolfram.com/Bessel-TypeFunctions/AiryAiPrime/16/01/01/0001/
if (3*m).is_integer:
c = M[c]
d = M[d]
n = M[n]
pf = (d**m * z**(n*m)) / (d * z**n)**m
newarg = c * d**m * z**(n*m)
return S.Half * ((pf + S.One)*airyaiprime(newarg) + (pf - S.One)/sqrt(3)*airybiprime(newarg))
class airybiprime(AiryBase):
r"""
The derivative $\operatorname{Bi}^\prime$ of the Airy function of the first
kind.
Explanation
===========
The Airy function $\operatorname{Bi}^\prime(z)$ is defined to be the
function
.. math::
\operatorname{Bi}^\prime(z) := \frac{\mathrm{d} \operatorname{Bi}(z)}{\mathrm{d} z}.
Examples
========
Create an Airy function object:
>>> from sympy import airybiprime
>>> from sympy.abc import z
>>> airybiprime(z)
airybiprime(z)
Several special values are known:
>>> airybiprime(0)
3**(1/6)/gamma(1/3)
>>> from sympy import oo
>>> airybiprime(oo)
oo
>>> airybiprime(-oo)
0
The Airy function obeys the mirror symmetry:
>>> from sympy import conjugate
>>> conjugate(airybiprime(z))
airybiprime(conjugate(z))
Differentiation with respect to $z$ is supported:
>>> from sympy import diff
>>> diff(airybiprime(z), z)
z*airybi(z)
>>> diff(airybiprime(z), z, 2)
z*airybiprime(z) + airybi(z)
Series expansion is also supported:
>>> from sympy import series
>>> series(airybiprime(z), z, 0, 3)
3**(1/6)/gamma(1/3) + 3**(5/6)*z**2/(6*gamma(2/3)) + O(z**3)
We can numerically evaluate the Airy function to arbitrary precision
on the whole complex plane:
>>> airybiprime(-2).evalf(50)
0.27879516692116952268509756941098324140300059345163
Rewrite $\operatorname{Bi}^\prime(z)$ in terms of hypergeometric functions:
>>> from sympy import hyper
>>> airybiprime(z).rewrite(hyper)
3**(5/6)*z**2*hyper((), (5/3,), z**3/9)/(6*gamma(2/3)) + 3**(1/6)*hyper((), (1/3,), z**3/9)/gamma(1/3)
See Also
========
airyai: Airy function of the first kind.
airybi: Airy function of the second kind.
airyaiprime: Derivative of the Airy function of the first kind.
References
==========
.. [1] https://en.wikipedia.org/wiki/Airy_function
.. [2] http://dlmf.nist.gov/9
.. [3] http://www.encyclopediaofmath.org/index.php/Airy_functions
.. [4] http://mathworld.wolfram.com/AiryFunctions.html
"""
nargs = 1
unbranched = True
@classmethod
def eval(cls, arg):
if arg.is_Number:
if arg is S.NaN:
return S.NaN
elif arg is S.Infinity:
return S.Infinity
elif arg is S.NegativeInfinity:
return S.Zero
elif arg.is_zero:
return 3**Rational(1, 6) / gamma(Rational(1, 3))
if arg.is_zero:
return 3**Rational(1, 6) / gamma(Rational(1, 3))
def fdiff(self, argindex=1):
if argindex == 1:
return self.args[0]*airybi(self.args[0])
else:
raise ArgumentIndexError(self, argindex)
def _eval_evalf(self, prec):
from mpmath import mp, workprec
from sympy import Expr
z = self.args[0]._to_mpmath(prec)
with workprec(prec):
res = mp.airybi(z, derivative=1)
return Expr._from_mpmath(res, prec)
def _eval_rewrite_as_besselj(self, z, **kwargs):
tt = Rational(2, 3)
a = tt * Pow(-z, Rational(3, 2))
if re(z).is_negative:
return -z/sqrt(3) * (besselj(-tt, a) + besselj(tt, a))
def _eval_rewrite_as_besseli(self, z, **kwargs):
ot = Rational(1, 3)
tt = Rational(2, 3)
a = tt * Pow(z, Rational(3, 2))
if re(z).is_positive:
return z/sqrt(3) * (besseli(-tt, a) + besseli(tt, a))
else:
a = Pow(z, Rational(3, 2))
b = Pow(a, tt)
c = Pow(a, -tt)
return sqrt(ot) * (b*besseli(-tt, tt*a) + z**2*c*besseli(tt, tt*a))
def _eval_rewrite_as_hyper(self, z, **kwargs):
pf1 = z**2 / (2*root(3, 6)*gamma(Rational(2, 3)))
pf2 = root(3, 6) / gamma(Rational(1, 3))
return pf1 * hyper([], [Rational(5, 3)], z**3/9) + pf2 * hyper([], [Rational(1, 3)], z**3/9)
def _eval_expand_func(self, **hints):
arg = self.args[0]
symbs = arg.free_symbols
if len(symbs) == 1:
z = symbs.pop()
c = Wild("c", exclude=[z])
d = Wild("d", exclude=[z])
m = Wild("m", exclude=[z])
n = Wild("n", exclude=[z])
M = arg.match(c*(d*z**n)**m)
if M is not None:
m = M[m]
# The transformation is in principle
# given by 03.08.16.0001.01 but note
# that there is an error in this formula.
# http://functions.wolfram.com/Bessel-TypeFunctions/AiryBiPrime/16/01/01/0001/
if (3*m).is_integer:
c = M[c]
d = M[d]
n = M[n]
pf = (d**m * z**(n*m)) / (d * z**n)**m
newarg = c * d**m * z**(n*m)
return S.Half * (sqrt(3)*(pf - S.One)*airyaiprime(newarg) + (pf + S.One)*airybiprime(newarg))
class marcumq(Function):
r"""
The Marcum Q-function.
Explanation
===========
The Marcum Q-function is defined by the meromorphic continuation of
.. math::
Q_m(a, b) = a^{- m + 1} \int_{b}^{\infty} x^{m} e^{- \frac{a^{2}}{2} - \frac{x^{2}}{2}} I_{m - 1}\left(a x\right)\, dx
Examples
========
>>> from sympy import marcumq
>>> from sympy.abc import m, a, b
>>> marcumq(m, a, b)
marcumq(m, a, b)
Special values:
>>> marcumq(m, 0, b)
uppergamma(m, b**2/2)/gamma(m)
>>> marcumq(0, 0, 0)
0
>>> marcumq(0, a, 0)
1 - exp(-a**2/2)
>>> marcumq(1, a, a)
1/2 + exp(-a**2)*besseli(0, a**2)/2
>>> marcumq(2, a, a)
1/2 + exp(-a**2)*besseli(0, a**2)/2 + exp(-a**2)*besseli(1, a**2)
Differentiation with respect to $a$ and $b$ is supported:
>>> from sympy import diff
>>> diff(marcumq(m, a, b), a)
a*(-marcumq(m, a, b) + marcumq(m + 1, a, b))
>>> diff(marcumq(m, a, b), b)
-a**(1 - m)*b**m*exp(-a**2/2 - b**2/2)*besseli(m - 1, a*b)
References
==========
.. [1] https://en.wikipedia.org/wiki/Marcum_Q-function
.. [2] http://mathworld.wolfram.com/MarcumQ-Function.html
"""
@classmethod
def eval(cls, m, a, b):
from sympy import exp, uppergamma
if a is S.Zero:
if m is S.Zero and b is S.Zero:
return S.Zero
return uppergamma(m, b**2 * S.Half) / gamma(m)
if m is S.Zero and b is S.Zero:
return 1 - 1 / exp(a**2 * S.Half)
if a == b:
if m is S.One:
return (1 + exp(-a**2) * besseli(0, a**2))*S.Half
if m == 2:
return S.Half + S.Half * exp(-a**2) * besseli(0, a**2) + exp(-a**2) * besseli(1, a**2)
if a.is_zero:
if m.is_zero and b.is_zero:
return S.Zero
return uppergamma(m, b**2*S.Half) / gamma(m)
if m.is_zero and b.is_zero:
return 1 - 1 / exp(a**2*S.Half)
def fdiff(self, argindex=2):
from sympy import exp
m, a, b = self.args
if argindex == 2:
return a * (-marcumq(m, a, b) + marcumq(1+m, a, b))
elif argindex == 3:
return (-b**m / a**(m-1)) * exp(-(a**2 + b**2)/2) * besseli(m-1, a*b)
else:
raise ArgumentIndexError(self, argindex)
def _eval_rewrite_as_Integral(self, m, a, b, **kwargs):
from sympy import Integral, exp, Dummy, oo
x = kwargs.get('x', Dummy('x'))
return a ** (1 - m) * \
Integral(x**m * exp(-(x**2 + a**2)/2) * besseli(m-1, a*x), [x, b, oo])
def _eval_rewrite_as_Sum(self, m, a, b, **kwargs):
from sympy import Sum, exp, Dummy, oo
k = kwargs.get('k', Dummy('k'))
return exp(-(a**2 + b**2) / 2) * Sum((a/b)**k * besseli(k, a*b), [k, 1-m, oo])
def _eval_rewrite_as_besseli(self, m, a, b, **kwargs):
if a == b:
from sympy import exp
if m == 1:
return (1 + exp(-a**2) * besseli(0, a**2)) / 2
if m.is_Integer and m >= 2:
s = sum([besseli(i, a**2) for i in range(1, m)])
return S.Half + exp(-a**2) * besseli(0, a**2) / 2 + exp(-a**2) * s
def _eval_is_zero(self):
if all(arg.is_zero for arg in self.args):
return True
|
81d184c9e3ce861b65d1069bdba9afd985a908c9a529265222f46920db2d3cc6 | """ This module contains various functions that are special cases
of incomplete gamma functions. It should probably be renamed. """
from sympy.core import Add, S, sympify, cacheit, pi, I, Rational
from sympy.core.function import Function, ArgumentIndexError
from sympy.core.symbol import Symbol
from sympy.functions.combinatorial.factorials import factorial, factorial2, RisingFactorial
from sympy.functions.elementary.complexes import re
from sympy.functions.elementary.integers import floor
from sympy.functions.elementary.miscellaneous import sqrt, root
from sympy.functions.elementary.exponential import exp, log
from sympy.functions.elementary.complexes import polar_lift
from sympy.functions.elementary.hyperbolic import cosh, sinh
from sympy.functions.elementary.trigonometric import cos, sin, sinc
from sympy.functions.special.hyper import hyper, meijerg
# TODO series expansions
# TODO see the "Note:" in Ei
# Helper function
def real_to_real_as_real_imag(self, deep=True, **hints):
if self.args[0].is_extended_real:
if deep:
hints['complex'] = False
return (self.expand(deep, **hints), S.Zero)
else:
return (self, S.Zero)
if deep:
x, y = self.args[0].expand(deep, **hints).as_real_imag()
else:
x, y = self.args[0].as_real_imag()
re = (self.func(x + I*y) + self.func(x - I*y))/2
im = (self.func(x + I*y) - self.func(x - I*y))/(2*I)
return (re, im)
###############################################################################
################################ ERROR FUNCTION ###############################
###############################################################################
class erf(Function):
r"""
The Gauss error function.
Explanation
===========
This function is defined as:
.. math ::
\mathrm{erf}(x) = \frac{2}{\sqrt{\pi}} \int_0^x e^{-t^2} \mathrm{d}t.
Examples
========
>>> from sympy import I, oo, erf
>>> from sympy.abc import z
Several special values are known:
>>> erf(0)
0
>>> erf(oo)
1
>>> erf(-oo)
-1
>>> erf(I*oo)
oo*I
>>> erf(-I*oo)
-oo*I
In general one can pull out factors of -1 and $I$ from the argument:
>>> erf(-z)
-erf(z)
The error function obeys the mirror symmetry:
>>> from sympy import conjugate
>>> conjugate(erf(z))
erf(conjugate(z))
Differentiation with respect to $z$ is supported:
>>> from sympy import diff
>>> diff(erf(z), z)
2*exp(-z**2)/sqrt(pi)
We can numerically evaluate the error function to arbitrary precision
on the whole complex plane:
>>> erf(4).evalf(30)
0.999999984582742099719981147840
>>> erf(-4*I).evalf(30)
-1296959.73071763923152794095062*I
See Also
========
erfc: Complementary error function.
erfi: Imaginary error function.
erf2: Two-argument error function.
erfinv: Inverse error function.
erfcinv: Inverse Complementary error function.
erf2inv: Inverse two-argument error function.
References
==========
.. [1] https://en.wikipedia.org/wiki/Error_function
.. [2] http://dlmf.nist.gov/7
.. [3] http://mathworld.wolfram.com/Erf.html
.. [4] http://functions.wolfram.com/GammaBetaErf/Erf
"""
unbranched = True
def fdiff(self, argindex=1):
if argindex == 1:
return 2*exp(-self.args[0]**2)/sqrt(S.Pi)
else:
raise ArgumentIndexError(self, argindex)
def inverse(self, argindex=1):
"""
Returns the inverse of this function.
"""
return erfinv
@classmethod
def eval(cls, arg):
if arg.is_Number:
if arg is S.NaN:
return S.NaN
elif arg is S.Infinity:
return S.One
elif arg is S.NegativeInfinity:
return S.NegativeOne
elif arg.is_zero:
return S.Zero
if isinstance(arg, erfinv):
return arg.args[0]
if isinstance(arg, erfcinv):
return S.One - arg.args[0]
if arg.is_zero:
return S.Zero
# Only happens with unevaluated erf2inv
if isinstance(arg, erf2inv) and arg.args[0].is_zero:
return arg.args[1]
# Try to pull out factors of I
t = arg.extract_multiplicatively(S.ImaginaryUnit)
if t is S.Infinity or t is S.NegativeInfinity:
return arg
# Try to pull out factors of -1
if arg.could_extract_minus_sign():
return -cls(-arg)
@staticmethod
@cacheit
def taylor_term(n, x, *previous_terms):
if n < 0 or n % 2 == 0:
return S.Zero
else:
x = sympify(x)
k = floor((n - 1)/S(2))
if len(previous_terms) > 2:
return -previous_terms[-2] * x**2 * (n - 2)/(n*k)
else:
return 2*(-1)**k * x**n/(n*factorial(k)*sqrt(S.Pi))
def _eval_conjugate(self):
return self.func(self.args[0].conjugate())
def _eval_is_real(self):
return self.args[0].is_extended_real
def _eval_is_finite(self):
if self.args[0].is_finite:
return True
else:
return self.args[0].is_extended_real
def _eval_is_zero(self):
if self.args[0].is_zero:
return True
def _eval_rewrite_as_uppergamma(self, z, **kwargs):
from sympy import uppergamma
return sqrt(z**2)/z*(S.One - uppergamma(S.Half, z**2)/sqrt(S.Pi))
def _eval_rewrite_as_fresnels(self, z, **kwargs):
arg = (S.One - S.ImaginaryUnit)*z/sqrt(pi)
return (S.One + S.ImaginaryUnit)*(fresnelc(arg) - I*fresnels(arg))
def _eval_rewrite_as_fresnelc(self, z, **kwargs):
arg = (S.One - S.ImaginaryUnit)*z/sqrt(pi)
return (S.One + S.ImaginaryUnit)*(fresnelc(arg) - I*fresnels(arg))
def _eval_rewrite_as_meijerg(self, z, **kwargs):
return z/sqrt(pi)*meijerg([S.Half], [], [0], [Rational(-1, 2)], z**2)
def _eval_rewrite_as_hyper(self, z, **kwargs):
return 2*z/sqrt(pi)*hyper([S.Half], [3*S.Half], -z**2)
def _eval_rewrite_as_expint(self, z, **kwargs):
return sqrt(z**2)/z - z*expint(S.Half, z**2)/sqrt(S.Pi)
def _eval_rewrite_as_tractable(self, z, limitvar=None, **kwargs):
from sympy.series.limits import limit
if limitvar:
lim = limit(z, limitvar, S.Infinity)
if lim is S.NegativeInfinity:
return S.NegativeOne + _erfs(-z)*exp(-z**2)
return S.One - _erfs(z)*exp(-z**2)
def _eval_rewrite_as_erfc(self, z, **kwargs):
return S.One - erfc(z)
def _eval_rewrite_as_erfi(self, z, **kwargs):
return -I*erfi(I*z)
def _eval_as_leading_term(self, x, logx=None, cdir=0):
arg = self.args[0].as_leading_term(x, logx=logx, cdir=cdir)
arg0 = arg.subs(x, 0)
if arg0 is S.ComplexInfinity:
arg0 = arg.limit(x, 0, dir='-' if cdir == -1 else '+')
if x in arg.free_symbols and arg0.is_zero:
return 2*arg/sqrt(pi)
else:
return self.func(arg0)
def _eval_aseries(self, n, args0, x, logx):
from sympy.series.order import Order
from sympy import ceiling
point = args0[0]
if point in [S.Infinity, S.NegativeInfinity]:
z = self.args[0]
try:
_, ex = z.leadterm(x)
except (ValueError, NotImplementedError):
return self
ex = -ex # as x->1/x for aseries
if ex.is_positive:
newn = ceiling(n/ex)
s = [(-1)**k * factorial2(2*k - 1) / (z**(2*k + 1) * 2**k)
for k in range(0, newn)] + [Order(1/z**newn, x)]
return S.One - (exp(-z**2)/sqrt(pi)) * Add(*s)
return super(erf, self)._eval_aseries(n, args0, x, logx)
as_real_imag = real_to_real_as_real_imag
class erfc(Function):
r"""
Complementary Error Function.
Explanation
===========
The function is defined as:
.. math ::
\mathrm{erfc}(x) = \frac{2}{\sqrt{\pi}} \int_x^\infty e^{-t^2} \mathrm{d}t
Examples
========
>>> from sympy import I, oo, erfc
>>> from sympy.abc import z
Several special values are known:
>>> erfc(0)
1
>>> erfc(oo)
0
>>> erfc(-oo)
2
>>> erfc(I*oo)
-oo*I
>>> erfc(-I*oo)
oo*I
The error function obeys the mirror symmetry:
>>> from sympy import conjugate
>>> conjugate(erfc(z))
erfc(conjugate(z))
Differentiation with respect to $z$ is supported:
>>> from sympy import diff
>>> diff(erfc(z), z)
-2*exp(-z**2)/sqrt(pi)
It also follows
>>> erfc(-z)
2 - erfc(z)
We can numerically evaluate the complementary error function to arbitrary
precision on the whole complex plane:
>>> erfc(4).evalf(30)
0.0000000154172579002800188521596734869
>>> erfc(4*I).evalf(30)
1.0 - 1296959.73071763923152794095062*I
See Also
========
erf: Gaussian error function.
erfi: Imaginary error function.
erf2: Two-argument error function.
erfinv: Inverse error function.
erfcinv: Inverse Complementary error function.
erf2inv: Inverse two-argument error function.
References
==========
.. [1] https://en.wikipedia.org/wiki/Error_function
.. [2] http://dlmf.nist.gov/7
.. [3] http://mathworld.wolfram.com/Erfc.html
.. [4] http://functions.wolfram.com/GammaBetaErf/Erfc
"""
unbranched = True
def fdiff(self, argindex=1):
if argindex == 1:
return -2*exp(-self.args[0]**2)/sqrt(S.Pi)
else:
raise ArgumentIndexError(self, argindex)
def inverse(self, argindex=1):
"""
Returns the inverse of this function.
"""
return erfcinv
@classmethod
def eval(cls, arg):
if arg.is_Number:
if arg is S.NaN:
return S.NaN
elif arg is S.Infinity:
return S.Zero
elif arg.is_zero:
return S.One
if isinstance(arg, erfinv):
return S.One - arg.args[0]
if isinstance(arg, erfcinv):
return arg.args[0]
if arg.is_zero:
return S.One
# Try to pull out factors of I
t = arg.extract_multiplicatively(S.ImaginaryUnit)
if t is S.Infinity or t is S.NegativeInfinity:
return -arg
# Try to pull out factors of -1
if arg.could_extract_minus_sign():
return S(2) - cls(-arg)
@staticmethod
@cacheit
def taylor_term(n, x, *previous_terms):
if n == 0:
return S.One
elif n < 0 or n % 2 == 0:
return S.Zero
else:
x = sympify(x)
k = floor((n - 1)/S(2))
if len(previous_terms) > 2:
return -previous_terms[-2] * x**2 * (n - 2)/(n*k)
else:
return -2*(-1)**k * x**n/(n*factorial(k)*sqrt(S.Pi))
def _eval_conjugate(self):
return self.func(self.args[0].conjugate())
def _eval_is_real(self):
return self.args[0].is_extended_real
def _eval_rewrite_as_tractable(self, z, limitvar=None, **kwargs):
return self.rewrite(erf).rewrite("tractable", deep=True, limitvar=limitvar)
def _eval_rewrite_as_erf(self, z, **kwargs):
return S.One - erf(z)
def _eval_rewrite_as_erfi(self, z, **kwargs):
return S.One + I*erfi(I*z)
def _eval_rewrite_as_fresnels(self, z, **kwargs):
arg = (S.One - S.ImaginaryUnit)*z/sqrt(pi)
return S.One - (S.One + S.ImaginaryUnit)*(fresnelc(arg) - I*fresnels(arg))
def _eval_rewrite_as_fresnelc(self, z, **kwargs):
arg = (S.One-S.ImaginaryUnit)*z/sqrt(pi)
return S.One - (S.One + S.ImaginaryUnit)*(fresnelc(arg) - I*fresnels(arg))
def _eval_rewrite_as_meijerg(self, z, **kwargs):
return S.One - z/sqrt(pi)*meijerg([S.Half], [], [0], [Rational(-1, 2)], z**2)
def _eval_rewrite_as_hyper(self, z, **kwargs):
return S.One - 2*z/sqrt(pi)*hyper([S.Half], [3*S.Half], -z**2)
def _eval_rewrite_as_uppergamma(self, z, **kwargs):
from sympy import uppergamma
return S.One - sqrt(z**2)/z*(S.One - uppergamma(S.Half, z**2)/sqrt(S.Pi))
def _eval_rewrite_as_expint(self, z, **kwargs):
return S.One - sqrt(z**2)/z + z*expint(S.Half, z**2)/sqrt(S.Pi)
def _eval_expand_func(self, **hints):
return self.rewrite(erf)
def _eval_as_leading_term(self, x, logx=None, cdir=0):
arg = self.args[0].as_leading_term(x, logx=logx, cdir=cdir)
arg0 = arg.subs(x, 0)
if arg0 is S.ComplexInfinity:
arg0 = arg.limit(x, 0, dir='-' if cdir == -1 else '+')
if arg0.is_zero:
return S.One
else:
return self.func(arg0)
as_real_imag = real_to_real_as_real_imag
def _eval_aseries(self, n, args0, x, logx):
return S.One - erf(*self.args)._eval_aseries(n, args0, x, logx)
class erfi(Function):
r"""
Imaginary error function.
Explanation
===========
The function erfi is defined as:
.. math ::
\mathrm{erfi}(x) = \frac{2}{\sqrt{\pi}} \int_0^x e^{t^2} \mathrm{d}t
Examples
========
>>> from sympy import I, oo, erfi
>>> from sympy.abc import z
Several special values are known:
>>> erfi(0)
0
>>> erfi(oo)
oo
>>> erfi(-oo)
-oo
>>> erfi(I*oo)
I
>>> erfi(-I*oo)
-I
In general one can pull out factors of -1 and $I$ from the argument:
>>> erfi(-z)
-erfi(z)
>>> from sympy import conjugate
>>> conjugate(erfi(z))
erfi(conjugate(z))
Differentiation with respect to $z$ is supported:
>>> from sympy import diff
>>> diff(erfi(z), z)
2*exp(z**2)/sqrt(pi)
We can numerically evaluate the imaginary error function to arbitrary
precision on the whole complex plane:
>>> erfi(2).evalf(30)
18.5648024145755525987042919132
>>> erfi(-2*I).evalf(30)
-0.995322265018952734162069256367*I
See Also
========
erf: Gaussian error function.
erfc: Complementary error function.
erf2: Two-argument error function.
erfinv: Inverse error function.
erfcinv: Inverse Complementary error function.
erf2inv: Inverse two-argument error function.
References
==========
.. [1] https://en.wikipedia.org/wiki/Error_function
.. [2] http://mathworld.wolfram.com/Erfi.html
.. [3] http://functions.wolfram.com/GammaBetaErf/Erfi
"""
unbranched = True
def fdiff(self, argindex=1):
if argindex == 1:
return 2*exp(self.args[0]**2)/sqrt(S.Pi)
else:
raise ArgumentIndexError(self, argindex)
@classmethod
def eval(cls, z):
if z.is_Number:
if z is S.NaN:
return S.NaN
elif z.is_zero:
return S.Zero
elif z is S.Infinity:
return S.Infinity
if z.is_zero:
return S.Zero
# Try to pull out factors of -1
if z.could_extract_minus_sign():
return -cls(-z)
# Try to pull out factors of I
nz = z.extract_multiplicatively(I)
if nz is not None:
if nz is S.Infinity:
return I
if isinstance(nz, erfinv):
return I*nz.args[0]
if isinstance(nz, erfcinv):
return I*(S.One - nz.args[0])
# Only happens with unevaluated erf2inv
if isinstance(nz, erf2inv) and nz.args[0].is_zero:
return I*nz.args[1]
@staticmethod
@cacheit
def taylor_term(n, x, *previous_terms):
if n < 0 or n % 2 == 0:
return S.Zero
else:
x = sympify(x)
k = floor((n - 1)/S(2))
if len(previous_terms) > 2:
return previous_terms[-2] * x**2 * (n - 2)/(n*k)
else:
return 2 * x**n/(n*factorial(k)*sqrt(S.Pi))
def _eval_conjugate(self):
return self.func(self.args[0].conjugate())
def _eval_is_extended_real(self):
return self.args[0].is_extended_real
def _eval_is_zero(self):
if self.args[0].is_zero:
return True
def _eval_rewrite_as_tractable(self, z, limitvar=None, **kwargs):
return self.rewrite(erf).rewrite("tractable", deep=True, limitvar=limitvar)
def _eval_rewrite_as_erf(self, z, **kwargs):
return -I*erf(I*z)
def _eval_rewrite_as_erfc(self, z, **kwargs):
return I*erfc(I*z) - I
def _eval_rewrite_as_fresnels(self, z, **kwargs):
arg = (S.One + S.ImaginaryUnit)*z/sqrt(pi)
return (S.One - S.ImaginaryUnit)*(fresnelc(arg) - I*fresnels(arg))
def _eval_rewrite_as_fresnelc(self, z, **kwargs):
arg = (S.One + S.ImaginaryUnit)*z/sqrt(pi)
return (S.One - S.ImaginaryUnit)*(fresnelc(arg) - I*fresnels(arg))
def _eval_rewrite_as_meijerg(self, z, **kwargs):
return z/sqrt(pi)*meijerg([S.Half], [], [0], [Rational(-1, 2)], -z**2)
def _eval_rewrite_as_hyper(self, z, **kwargs):
return 2*z/sqrt(pi)*hyper([S.Half], [3*S.Half], z**2)
def _eval_rewrite_as_uppergamma(self, z, **kwargs):
from sympy import uppergamma
return sqrt(-z**2)/z*(uppergamma(S.Half, -z**2)/sqrt(S.Pi) - S.One)
def _eval_rewrite_as_expint(self, z, **kwargs):
return sqrt(-z**2)/z - z*expint(S.Half, -z**2)/sqrt(S.Pi)
def _eval_expand_func(self, **hints):
return self.rewrite(erf)
as_real_imag = real_to_real_as_real_imag
def _eval_as_leading_term(self, x, logx=None, cdir=0):
arg = self.args[0].as_leading_term(x, logx=logx, cdir=cdir)
arg0 = arg.subs(x, 0)
if x in arg.free_symbols and arg0.is_zero:
return 2*arg/sqrt(pi)
elif arg0.is_finite:
return self.func(arg0)
return self.func(arg)
def _eval_aseries(self, n, args0, x, logx):
from sympy.series.order import Order
point = args0[0]
if point is S.Infinity:
z = self.args[0]
s = [factorial2(2*k - 1) / (2**k * z**(2*k + 1))
for k in range(0, n)] + [Order(1/z**n, x)]
return -S.ImaginaryUnit + (exp(z**2)/sqrt(pi)) * Add(*s)
return super(erfi, self)._eval_aseries(n, args0, x, logx)
class erf2(Function):
r"""
Two-argument error function.
Explanation
===========
This function is defined as:
.. math ::
\mathrm{erf2}(x, y) = \frac{2}{\sqrt{\pi}} \int_x^y e^{-t^2} \mathrm{d}t
Examples
========
>>> from sympy import oo, erf2
>>> from sympy.abc import x, y
Several special values are known:
>>> erf2(0, 0)
0
>>> erf2(x, x)
0
>>> erf2(x, oo)
1 - erf(x)
>>> erf2(x, -oo)
-erf(x) - 1
>>> erf2(oo, y)
erf(y) - 1
>>> erf2(-oo, y)
erf(y) + 1
In general one can pull out factors of -1:
>>> erf2(-x, -y)
-erf2(x, y)
The error function obeys the mirror symmetry:
>>> from sympy import conjugate
>>> conjugate(erf2(x, y))
erf2(conjugate(x), conjugate(y))
Differentiation with respect to $x$, $y$ is supported:
>>> from sympy import diff
>>> diff(erf2(x, y), x)
-2*exp(-x**2)/sqrt(pi)
>>> diff(erf2(x, y), y)
2*exp(-y**2)/sqrt(pi)
See Also
========
erf: Gaussian error function.
erfc: Complementary error function.
erfi: Imaginary error function.
erfinv: Inverse error function.
erfcinv: Inverse Complementary error function.
erf2inv: Inverse two-argument error function.
References
==========
.. [1] http://functions.wolfram.com/GammaBetaErf/Erf2/
"""
def fdiff(self, argindex):
x, y = self.args
if argindex == 1:
return -2*exp(-x**2)/sqrt(S.Pi)
elif argindex == 2:
return 2*exp(-y**2)/sqrt(S.Pi)
else:
raise ArgumentIndexError(self, argindex)
@classmethod
def eval(cls, x, y):
I = S.Infinity
N = S.NegativeInfinity
O = S.Zero
if x is S.NaN or y is S.NaN:
return S.NaN
elif x == y:
return S.Zero
elif (x is I or x is N or x is O) or (y is I or y is N or y is O):
return erf(y) - erf(x)
if isinstance(y, erf2inv) and y.args[0] == x:
return y.args[1]
if x.is_zero or y.is_zero or x.is_extended_real and x.is_infinite or \
y.is_extended_real and y.is_infinite:
return erf(y) - erf(x)
#Try to pull out -1 factor
sign_x = x.could_extract_minus_sign()
sign_y = y.could_extract_minus_sign()
if (sign_x and sign_y):
return -cls(-x, -y)
elif (sign_x or sign_y):
return erf(y)-erf(x)
def _eval_conjugate(self):
return self.func(self.args[0].conjugate(), self.args[1].conjugate())
def _eval_is_extended_real(self):
return self.args[0].is_extended_real and self.args[1].is_extended_real
def _eval_rewrite_as_erf(self, x, y, **kwargs):
return erf(y) - erf(x)
def _eval_rewrite_as_erfc(self, x, y, **kwargs):
return erfc(x) - erfc(y)
def _eval_rewrite_as_erfi(self, x, y, **kwargs):
return I*(erfi(I*x)-erfi(I*y))
def _eval_rewrite_as_fresnels(self, x, y, **kwargs):
return erf(y).rewrite(fresnels) - erf(x).rewrite(fresnels)
def _eval_rewrite_as_fresnelc(self, x, y, **kwargs):
return erf(y).rewrite(fresnelc) - erf(x).rewrite(fresnelc)
def _eval_rewrite_as_meijerg(self, x, y, **kwargs):
return erf(y).rewrite(meijerg) - erf(x).rewrite(meijerg)
def _eval_rewrite_as_hyper(self, x, y, **kwargs):
return erf(y).rewrite(hyper) - erf(x).rewrite(hyper)
def _eval_rewrite_as_uppergamma(self, x, y, **kwargs):
from sympy import uppergamma
return (sqrt(y**2)/y*(S.One - uppergamma(S.Half, y**2)/sqrt(S.Pi)) -
sqrt(x**2)/x*(S.One - uppergamma(S.Half, x**2)/sqrt(S.Pi)))
def _eval_rewrite_as_expint(self, x, y, **kwargs):
return erf(y).rewrite(expint) - erf(x).rewrite(expint)
def _eval_expand_func(self, **hints):
return self.rewrite(erf)
class erfinv(Function):
r"""
Inverse Error Function. The erfinv function is defined as:
.. math ::
\mathrm{erf}(x) = y \quad \Rightarrow \quad \mathrm{erfinv}(y) = x
Examples
========
>>> from sympy import erfinv
>>> from sympy.abc import x
Several special values are known:
>>> erfinv(0)
0
>>> erfinv(1)
oo
Differentiation with respect to $x$ is supported:
>>> from sympy import diff
>>> diff(erfinv(x), x)
sqrt(pi)*exp(erfinv(x)**2)/2
We can numerically evaluate the inverse error function to arbitrary
precision on [-1, 1]:
>>> erfinv(0.2).evalf(30)
0.179143454621291692285822705344
See Also
========
erf: Gaussian error function.
erfc: Complementary error function.
erfi: Imaginary error function.
erf2: Two-argument error function.
erfcinv: Inverse Complementary error function.
erf2inv: Inverse two-argument error function.
References
==========
.. [1] https://en.wikipedia.org/wiki/Error_function#Inverse_functions
.. [2] http://functions.wolfram.com/GammaBetaErf/InverseErf/
"""
def fdiff(self, argindex =1):
if argindex == 1:
return sqrt(S.Pi)*exp(self.func(self.args[0])**2)*S.Half
else :
raise ArgumentIndexError(self, argindex)
def inverse(self, argindex=1):
"""
Returns the inverse of this function.
"""
return erf
@classmethod
def eval(cls, z):
if z is S.NaN:
return S.NaN
elif z is S.NegativeOne:
return S.NegativeInfinity
elif z.is_zero:
return S.Zero
elif z is S.One:
return S.Infinity
if isinstance(z, erf) and z.args[0].is_extended_real:
return z.args[0]
if z.is_zero:
return S.Zero
# Try to pull out factors of -1
nz = z.extract_multiplicatively(-1)
if nz is not None and (isinstance(nz, erf) and (nz.args[0]).is_extended_real):
return -nz.args[0]
def _eval_rewrite_as_erfcinv(self, z, **kwargs):
return erfcinv(1-z)
def _eval_is_zero(self):
if self.args[0].is_zero:
return True
class erfcinv (Function):
r"""
Inverse Complementary Error Function. The erfcinv function is defined as:
.. math ::
\mathrm{erfc}(x) = y \quad \Rightarrow \quad \mathrm{erfcinv}(y) = x
Examples
========
>>> from sympy import erfcinv
>>> from sympy.abc import x
Several special values are known:
>>> erfcinv(1)
0
>>> erfcinv(0)
oo
Differentiation with respect to $x$ is supported:
>>> from sympy import diff
>>> diff(erfcinv(x), x)
-sqrt(pi)*exp(erfcinv(x)**2)/2
See Also
========
erf: Gaussian error function.
erfc: Complementary error function.
erfi: Imaginary error function.
erf2: Two-argument error function.
erfinv: Inverse error function.
erf2inv: Inverse two-argument error function.
References
==========
.. [1] https://en.wikipedia.org/wiki/Error_function#Inverse_functions
.. [2] http://functions.wolfram.com/GammaBetaErf/InverseErfc/
"""
def fdiff(self, argindex =1):
if argindex == 1:
return -sqrt(S.Pi)*exp(self.func(self.args[0])**2)*S.Half
else:
raise ArgumentIndexError(self, argindex)
def inverse(self, argindex=1):
"""
Returns the inverse of this function.
"""
return erfc
@classmethod
def eval(cls, z):
if z is S.NaN:
return S.NaN
elif z.is_zero:
return S.Infinity
elif z is S.One:
return S.Zero
elif z == 2:
return S.NegativeInfinity
if z.is_zero:
return S.Infinity
def _eval_rewrite_as_erfinv(self, z, **kwargs):
return erfinv(1-z)
class erf2inv(Function):
r"""
Two-argument Inverse error function. The erf2inv function is defined as:
.. math ::
\mathrm{erf2}(x, w) = y \quad \Rightarrow \quad \mathrm{erf2inv}(x, y) = w
Examples
========
>>> from sympy import erf2inv, oo
>>> from sympy.abc import x, y
Several special values are known:
>>> erf2inv(0, 0)
0
>>> erf2inv(1, 0)
1
>>> erf2inv(0, 1)
oo
>>> erf2inv(0, y)
erfinv(y)
>>> erf2inv(oo, y)
erfcinv(-y)
Differentiation with respect to $x$ and $y$ is supported:
>>> from sympy import diff
>>> diff(erf2inv(x, y), x)
exp(-x**2 + erf2inv(x, y)**2)
>>> diff(erf2inv(x, y), y)
sqrt(pi)*exp(erf2inv(x, y)**2)/2
See Also
========
erf: Gaussian error function.
erfc: Complementary error function.
erfi: Imaginary error function.
erf2: Two-argument error function.
erfinv: Inverse error function.
erfcinv: Inverse complementary error function.
References
==========
.. [1] http://functions.wolfram.com/GammaBetaErf/InverseErf2/
"""
def fdiff(self, argindex):
x, y = self.args
if argindex == 1:
return exp(self.func(x,y)**2-x**2)
elif argindex == 2:
return sqrt(S.Pi)*S.Half*exp(self.func(x,y)**2)
else:
raise ArgumentIndexError(self, argindex)
@classmethod
def eval(cls, x, y):
if x is S.NaN or y is S.NaN:
return S.NaN
elif x.is_zero and y.is_zero:
return S.Zero
elif x.is_zero and y is S.One:
return S.Infinity
elif x is S.One and y.is_zero:
return S.One
elif x.is_zero:
return erfinv(y)
elif x is S.Infinity:
return erfcinv(-y)
elif y.is_zero:
return x
elif y is S.Infinity:
return erfinv(x)
if x.is_zero:
if y.is_zero:
return S.Zero
else:
return erfinv(y)
if y.is_zero:
return x
def _eval_is_zero(self):
x, y = self.args
if x.is_zero and y.is_zero:
return True
###############################################################################
#################### EXPONENTIAL INTEGRALS ####################################
###############################################################################
class Ei(Function):
r"""
The classical exponential integral.
Explanation
===========
For use in SymPy, this function is defined as
.. math:: \operatorname{Ei}(x) = \sum_{n=1}^\infty \frac{x^n}{n\, n!}
+ \log(x) + \gamma,
where $\gamma$ is the Euler-Mascheroni constant.
If $x$ is a polar number, this defines an analytic function on the
Riemann surface of the logarithm. Otherwise this defines an analytic
function in the cut plane $\mathbb{C} \setminus (-\infty, 0]$.
**Background**
The name exponential integral comes from the following statement:
.. math:: \operatorname{Ei}(x) = \int_{-\infty}^x \frac{e^t}{t} \mathrm{d}t
If the integral is interpreted as a Cauchy principal value, this statement
holds for $x > 0$ and $\operatorname{Ei}(x)$ as defined above.
Examples
========
>>> from sympy import Ei, polar_lift, exp_polar, I, pi
>>> from sympy.abc import x
>>> Ei(-1)
Ei(-1)
This yields a real value:
>>> Ei(-1).n(chop=True)
-0.219383934395520
On the other hand the analytic continuation is not real:
>>> Ei(polar_lift(-1)).n(chop=True)
-0.21938393439552 + 3.14159265358979*I
The exponential integral has a logarithmic branch point at the origin:
>>> Ei(x*exp_polar(2*I*pi))
Ei(x) + 2*I*pi
Differentiation is supported:
>>> Ei(x).diff(x)
exp(x)/x
The exponential integral is related to many other special functions.
For example:
>>> from sympy import expint, Shi
>>> Ei(x).rewrite(expint)
-expint(1, x*exp_polar(I*pi)) - I*pi
>>> Ei(x).rewrite(Shi)
Chi(x) + Shi(x)
See Also
========
expint: Generalised exponential integral.
E1: Special case of the generalised exponential integral.
li: Logarithmic integral.
Li: Offset logarithmic integral.
Si: Sine integral.
Ci: Cosine integral.
Shi: Hyperbolic sine integral.
Chi: Hyperbolic cosine integral.
uppergamma: Upper incomplete gamma function.
References
==========
.. [1] http://dlmf.nist.gov/6.6
.. [2] https://en.wikipedia.org/wiki/Exponential_integral
.. [3] Abramowitz & Stegun, section 5: http://people.math.sfu.ca/~cbm/aands/page_228.htm
"""
@classmethod
def eval(cls, z):
if z.is_zero:
return S.NegativeInfinity
elif z is S.Infinity:
return S.Infinity
elif z is S.NegativeInfinity:
return S.Zero
if z.is_zero:
return S.NegativeInfinity
nz, n = z.extract_branch_factor()
if n:
return Ei(nz) + 2*I*pi*n
def fdiff(self, argindex=1):
from sympy import unpolarify
arg = unpolarify(self.args[0])
if argindex == 1:
return exp(arg)/arg
else:
raise ArgumentIndexError(self, argindex)
def _eval_evalf(self, prec):
if (self.args[0]/polar_lift(-1)).is_positive:
return Function._eval_evalf(self, prec) + (I*pi)._eval_evalf(prec)
return Function._eval_evalf(self, prec)
def _eval_rewrite_as_uppergamma(self, z, **kwargs):
from sympy import uppergamma
# XXX this does not currently work usefully because uppergamma
# immediately turns into expint
return -uppergamma(0, polar_lift(-1)*z) - I*pi
def _eval_rewrite_as_expint(self, z, **kwargs):
return -expint(1, polar_lift(-1)*z) - I*pi
def _eval_rewrite_as_li(self, z, **kwargs):
if isinstance(z, log):
return li(z.args[0])
# TODO:
# Actually it only holds that:
# Ei(z) = li(exp(z))
# for -pi < imag(z) <= pi
return li(exp(z))
def _eval_rewrite_as_Si(self, z, **kwargs):
if z.is_negative:
return Shi(z) + Chi(z) - I*pi
else:
return Shi(z) + Chi(z)
_eval_rewrite_as_Ci = _eval_rewrite_as_Si
_eval_rewrite_as_Chi = _eval_rewrite_as_Si
_eval_rewrite_as_Shi = _eval_rewrite_as_Si
def _eval_rewrite_as_tractable(self, z, limitvar=None, **kwargs):
return exp(z) * _eis(z)
def _eval_as_leading_term(self, x, logx=None, cdir=0):
x0 = self.args[0].limit(x, 0)
if x0.is_zero:
f = self._eval_rewrite_as_Si(*self.args)
return f._eval_as_leading_term(x, logx=logx, cdir=cdir)
return super()._eval_as_leading_term(x, logx=logx, cdir=cdir)
def _eval_nseries(self, x, n, logx, cdir=0):
x0 = self.args[0].limit(x, 0)
if x0.is_zero:
f = self._eval_rewrite_as_Si(*self.args)
return f._eval_nseries(x, n, logx)
return super()._eval_nseries(x, n, logx)
def _eval_aseries(self, n, args0, x, logx):
from sympy.series.order import Order
point = args0[0]
if point is S.Infinity:
z = self.args[0]
s = [factorial(k) / (z)**k for k in range(0, n)] + \
[Order(1/z**n, x)]
return (exp(z)/z) * Add(*s)
return super(Ei, self)._eval_aseries(n, args0, x, logx)
class expint(Function):
r"""
Generalized exponential integral.
Explanation
===========
This function is defined as
.. math:: \operatorname{E}_\nu(z) = z^{\nu - 1} \Gamma(1 - \nu, z),
where $\Gamma(1 - \nu, z)$ is the upper incomplete gamma function
(``uppergamma``).
Hence for $z$ with positive real part we have
.. math:: \operatorname{E}_\nu(z)
= \int_1^\infty \frac{e^{-zt}}{t^\nu} \mathrm{d}t,
which explains the name.
The representation as an incomplete gamma function provides an analytic
continuation for $\operatorname{E}_\nu(z)$. If $\nu$ is a
non-positive integer, the exponential integral is thus an unbranched
function of $z$, otherwise there is a branch point at the origin.
Refer to the incomplete gamma function documentation for details of the
branching behavior.
Examples
========
>>> from sympy import expint, S
>>> from sympy.abc import nu, z
Differentiation is supported. Differentiation with respect to $z$ further
explains the name: for integral orders, the exponential integral is an
iterated integral of the exponential function.
>>> expint(nu, z).diff(z)
-expint(nu - 1, z)
Differentiation with respect to $\nu$ has no classical expression:
>>> expint(nu, z).diff(nu)
-z**(nu - 1)*meijerg(((), (1, 1)), ((0, 0, 1 - nu), ()), z)
At non-postive integer orders, the exponential integral reduces to the
exponential function:
>>> expint(0, z)
exp(-z)/z
>>> expint(-1, z)
exp(-z)/z + exp(-z)/z**2
At half-integers it reduces to error functions:
>>> expint(S(1)/2, z)
sqrt(pi)*erfc(sqrt(z))/sqrt(z)
At positive integer orders it can be rewritten in terms of exponentials
and ``expint(1, z)``. Use ``expand_func()`` to do this:
>>> from sympy import expand_func
>>> expand_func(expint(5, z))
z**4*expint(1, z)/24 + (-z**3 + z**2 - 2*z + 6)*exp(-z)/24
The generalised exponential integral is essentially equivalent to the
incomplete gamma function:
>>> from sympy import uppergamma
>>> expint(nu, z).rewrite(uppergamma)
z**(nu - 1)*uppergamma(1 - nu, z)
As such it is branched at the origin:
>>> from sympy import exp_polar, pi, I
>>> expint(4, z*exp_polar(2*pi*I))
I*pi*z**3/3 + expint(4, z)
>>> expint(nu, z*exp_polar(2*pi*I))
z**(nu - 1)*(exp(2*I*pi*nu) - 1)*gamma(1 - nu) + expint(nu, z)
See Also
========
Ei: Another related function called exponential integral.
E1: The classical case, returns expint(1, z).
li: Logarithmic integral.
Li: Offset logarithmic integral.
Si: Sine integral.
Ci: Cosine integral.
Shi: Hyperbolic sine integral.
Chi: Hyperbolic cosine integral.
uppergamma
References
==========
.. [1] http://dlmf.nist.gov/8.19
.. [2] http://functions.wolfram.com/GammaBetaErf/ExpIntegralE/
.. [3] https://en.wikipedia.org/wiki/Exponential_integral
"""
@classmethod
def eval(cls, nu, z):
from sympy import (unpolarify, expand_mul, uppergamma, exp, gamma,
factorial)
nu2 = unpolarify(nu)
if nu != nu2:
return expint(nu2, z)
if nu.is_Integer and nu <= 0 or (not nu.is_Integer and (2*nu).is_Integer):
return unpolarify(expand_mul(z**(nu - 1)*uppergamma(1 - nu, z)))
# Extract branching information. This can be deduced from what is
# explained in lowergamma.eval().
z, n = z.extract_branch_factor()
if n is S.Zero:
return
if nu.is_integer:
if not nu > 0:
return
return expint(nu, z) \
- 2*pi*I*n*(-1)**(nu - 1)/factorial(nu - 1)*unpolarify(z)**(nu - 1)
else:
return (exp(2*I*pi*nu*n) - 1)*z**(nu - 1)*gamma(1 - nu) + expint(nu, z)
def fdiff(self, argindex):
from sympy import meijerg
nu, z = self.args
if argindex == 1:
return -z**(nu - 1)*meijerg([], [1, 1], [0, 0, 1 - nu], [], z)
elif argindex == 2:
return -expint(nu - 1, z)
else:
raise ArgumentIndexError(self, argindex)
def _eval_rewrite_as_uppergamma(self, nu, z, **kwargs):
from sympy import uppergamma
return z**(nu - 1)*uppergamma(1 - nu, z)
def _eval_rewrite_as_Ei(self, nu, z, **kwargs):
from sympy import exp_polar, unpolarify, exp, factorial
if nu == 1:
return -Ei(z*exp_polar(-I*pi)) - I*pi
elif nu.is_Integer and nu > 1:
# DLMF, 8.19.7
x = -unpolarify(z)
return x**(nu - 1)/factorial(nu - 1)*E1(z).rewrite(Ei) + \
exp(x)/factorial(nu - 1) * \
Add(*[factorial(nu - k - 2)*x**k for k in range(nu - 1)])
else:
return self
def _eval_expand_func(self, **hints):
return self.rewrite(Ei).rewrite(expint, **hints)
def _eval_rewrite_as_Si(self, nu, z, **kwargs):
if nu != 1:
return self
return Shi(z) - Chi(z)
_eval_rewrite_as_Ci = _eval_rewrite_as_Si
_eval_rewrite_as_Chi = _eval_rewrite_as_Si
_eval_rewrite_as_Shi = _eval_rewrite_as_Si
def _eval_nseries(self, x, n, logx, cdir=0):
if not self.args[0].has(x):
nu = self.args[0]
if nu == 1:
f = self._eval_rewrite_as_Si(*self.args)
return f._eval_nseries(x, n, logx)
elif nu.is_Integer and nu > 1:
f = self._eval_rewrite_as_Ei(*self.args)
return f._eval_nseries(x, n, logx)
return super()._eval_nseries(x, n, logx)
def _eval_aseries(self, n, args0, x, logx):
from sympy.series.order import Order
point = args0[1]
nu = self.args[0]
if point is S.Infinity:
z = self.args[1]
s = [(-1)**k * RisingFactorial(nu, k) / z**k for k in range(0, n)] + [Order(1/z**n, x)]
return (exp(-z)/z) * Add(*s)
return super(expint, self)._eval_aseries(n, args0, x, logx)
def _sage_(self):
import sage.all as sage
return sage.exp_integral_e(self.args[0]._sage_(), self.args[1]._sage_())
def E1(z):
"""
Classical case of the generalized exponential integral.
Explanation
===========
This is equivalent to ``expint(1, z)``.
Examples
========
>>> from sympy import E1
>>> E1(0)
expint(1, 0)
>>> E1(5)
expint(1, 5)
See Also
========
Ei: Exponential integral.
expint: Generalised exponential integral.
li: Logarithmic integral.
Li: Offset logarithmic integral.
Si: Sine integral.
Ci: Cosine integral.
Shi: Hyperbolic sine integral.
Chi: Hyperbolic cosine integral.
"""
return expint(1, z)
class li(Function):
r"""
The classical logarithmic integral.
Explanation
===========
For use in SymPy, this function is defined as
.. math:: \operatorname{li}(x) = \int_0^x \frac{1}{\log(t)} \mathrm{d}t \,.
Examples
========
>>> from sympy import I, oo, li
>>> from sympy.abc import z
Several special values are known:
>>> li(0)
0
>>> li(1)
-oo
>>> li(oo)
oo
Differentiation with respect to $z$ is supported:
>>> from sympy import diff
>>> diff(li(z), z)
1/log(z)
Defining the ``li`` function via an integral:
>>> from sympy import integrate
>>> integrate(li(z))
z*li(z) - Ei(2*log(z))
>>> integrate(li(z),z)
z*li(z) - Ei(2*log(z))
The logarithmic integral can also be defined in terms of ``Ei``:
>>> from sympy import Ei
>>> li(z).rewrite(Ei)
Ei(log(z))
>>> diff(li(z).rewrite(Ei), z)
1/log(z)
We can numerically evaluate the logarithmic integral to arbitrary precision
on the whole complex plane (except the singular points):
>>> li(2).evalf(30)
1.04516378011749278484458888919
>>> li(2*I).evalf(30)
1.0652795784357498247001125598 + 3.08346052231061726610939702133*I
We can even compute Soldner's constant by the help of mpmath:
>>> from mpmath import findroot
>>> findroot(li, 2)
1.45136923488338
Further transformations include rewriting ``li`` in terms of
the trigonometric integrals ``Si``, ``Ci``, ``Shi`` and ``Chi``:
>>> from sympy import Si, Ci, Shi, Chi
>>> li(z).rewrite(Si)
-log(I*log(z)) - log(1/log(z))/2 + log(log(z))/2 + Ci(I*log(z)) + Shi(log(z))
>>> li(z).rewrite(Ci)
-log(I*log(z)) - log(1/log(z))/2 + log(log(z))/2 + Ci(I*log(z)) + Shi(log(z))
>>> li(z).rewrite(Shi)
-log(1/log(z))/2 + log(log(z))/2 + Chi(log(z)) - Shi(log(z))
>>> li(z).rewrite(Chi)
-log(1/log(z))/2 + log(log(z))/2 + Chi(log(z)) - Shi(log(z))
See Also
========
Li: Offset logarithmic integral.
Ei: Exponential integral.
expint: Generalised exponential integral.
E1: Special case of the generalised exponential integral.
Si: Sine integral.
Ci: Cosine integral.
Shi: Hyperbolic sine integral.
Chi: Hyperbolic cosine integral.
References
==========
.. [1] https://en.wikipedia.org/wiki/Logarithmic_integral
.. [2] http://mathworld.wolfram.com/LogarithmicIntegral.html
.. [3] http://dlmf.nist.gov/6
.. [4] http://mathworld.wolfram.com/SoldnersConstant.html
"""
@classmethod
def eval(cls, z):
if z.is_zero:
return S.Zero
elif z is S.One:
return S.NegativeInfinity
elif z is S.Infinity:
return S.Infinity
if z.is_zero:
return S.Zero
def fdiff(self, argindex=1):
arg = self.args[0]
if argindex == 1:
return S.One / log(arg)
else:
raise ArgumentIndexError(self, argindex)
def _eval_conjugate(self):
z = self.args[0]
# Exclude values on the branch cut (-oo, 0)
if not z.is_extended_negative:
return self.func(z.conjugate())
def _eval_rewrite_as_Li(self, z, **kwargs):
return Li(z) + li(2)
def _eval_rewrite_as_Ei(self, z, **kwargs):
return Ei(log(z))
def _eval_rewrite_as_uppergamma(self, z, **kwargs):
from sympy import uppergamma
return (-uppergamma(0, -log(z)) +
S.Half*(log(log(z)) - log(S.One/log(z))) - log(-log(z)))
def _eval_rewrite_as_Si(self, z, **kwargs):
return (Ci(I*log(z)) - I*Si(I*log(z)) -
S.Half*(log(S.One/log(z)) - log(log(z))) - log(I*log(z)))
_eval_rewrite_as_Ci = _eval_rewrite_as_Si
def _eval_rewrite_as_Shi(self, z, **kwargs):
return (Chi(log(z)) - Shi(log(z)) - S.Half*(log(S.One/log(z)) - log(log(z))))
_eval_rewrite_as_Chi = _eval_rewrite_as_Shi
def _eval_rewrite_as_hyper(self, z, **kwargs):
return (log(z)*hyper((1, 1), (2, 2), log(z)) +
S.Half*(log(log(z)) - log(S.One/log(z))) + S.EulerGamma)
def _eval_rewrite_as_meijerg(self, z, **kwargs):
return (-log(-log(z)) - S.Half*(log(S.One/log(z)) - log(log(z)))
- meijerg(((), (1,)), ((0, 0), ()), -log(z)))
def _eval_rewrite_as_tractable(self, z, limitvar=None, **kwargs):
return z * _eis(log(z))
def _eval_nseries(self, x, n, logx, cdir=0):
z = self.args[0]
s = [(log(z))**k / (factorial(k) * k) for k in range(1, n)]
return S.EulerGamma + log(log(z)) + Add(*s)
def _eval_is_zero(self):
z = self.args[0]
if z.is_zero:
return True
class Li(Function):
r"""
The offset logarithmic integral.
Explanation
===========
For use in SymPy, this function is defined as
.. math:: \operatorname{Li}(x) = \operatorname{li}(x) - \operatorname{li}(2)
Examples
========
>>> from sympy import Li
>>> from sympy.abc import z
The following special value is known:
>>> Li(2)
0
Differentiation with respect to $z$ is supported:
>>> from sympy import diff
>>> diff(Li(z), z)
1/log(z)
The shifted logarithmic integral can be written in terms of $li(z)$:
>>> from sympy import li
>>> Li(z).rewrite(li)
li(z) - li(2)
We can numerically evaluate the logarithmic integral to arbitrary precision
on the whole complex plane (except the singular points):
>>> Li(2).evalf(30)
0
>>> Li(4).evalf(30)
1.92242131492155809316615998938
See Also
========
li: Logarithmic integral.
Ei: Exponential integral.
expint: Generalised exponential integral.
E1: Special case of the generalised exponential integral.
Si: Sine integral.
Ci: Cosine integral.
Shi: Hyperbolic sine integral.
Chi: Hyperbolic cosine integral.
References
==========
.. [1] https://en.wikipedia.org/wiki/Logarithmic_integral
.. [2] http://mathworld.wolfram.com/LogarithmicIntegral.html
.. [3] http://dlmf.nist.gov/6
"""
@classmethod
def eval(cls, z):
if z is S.Infinity:
return S.Infinity
elif z == S(2):
return S.Zero
def fdiff(self, argindex=1):
arg = self.args[0]
if argindex == 1:
return S.One / log(arg)
else:
raise ArgumentIndexError(self, argindex)
def _eval_evalf(self, prec):
return self.rewrite(li).evalf(prec)
def _eval_rewrite_as_li(self, z, **kwargs):
return li(z) - li(2)
def _eval_rewrite_as_tractable(self, z, limitvar=None, **kwargs):
return self.rewrite(li).rewrite("tractable", deep=True)
def _eval_nseries(self, x, n, logx, cdir=0):
f = self._eval_rewrite_as_li(*self.args)
return f._eval_nseries(x, n, logx)
###############################################################################
#################### TRIGONOMETRIC INTEGRALS ##################################
###############################################################################
class TrigonometricIntegral(Function):
""" Base class for trigonometric integrals. """
@classmethod
def eval(cls, z):
if z is S.Zero:
return cls._atzero
elif z is S.Infinity:
return cls._atinf()
elif z is S.NegativeInfinity:
return cls._atneginf()
if z.is_zero:
return cls._atzero
nz = z.extract_multiplicatively(polar_lift(I))
if nz is None and cls._trigfunc(0) == 0:
nz = z.extract_multiplicatively(I)
if nz is not None:
return cls._Ifactor(nz, 1)
nz = z.extract_multiplicatively(polar_lift(-I))
if nz is not None:
return cls._Ifactor(nz, -1)
nz = z.extract_multiplicatively(polar_lift(-1))
if nz is None and cls._trigfunc(0) == 0:
nz = z.extract_multiplicatively(-1)
if nz is not None:
return cls._minusfactor(nz)
nz, n = z.extract_branch_factor()
if n == 0 and nz == z:
return
return 2*pi*I*n*cls._trigfunc(0) + cls(nz)
def fdiff(self, argindex=1):
from sympy import unpolarify
arg = unpolarify(self.args[0])
if argindex == 1:
return self._trigfunc(arg)/arg
else:
raise ArgumentIndexError(self, argindex)
def _eval_rewrite_as_Ei(self, z, **kwargs):
return self._eval_rewrite_as_expint(z).rewrite(Ei)
def _eval_rewrite_as_uppergamma(self, z, **kwargs):
from sympy import uppergamma
return self._eval_rewrite_as_expint(z).rewrite(uppergamma)
def _eval_nseries(self, x, n, logx, cdir=0):
# NOTE this is fairly inefficient
from sympy import log, EulerGamma, Pow
n += 1
if self.args[0].subs(x, 0) != 0:
return super()._eval_nseries(x, n, logx)
baseseries = self._trigfunc(x)._eval_nseries(x, n, logx)
if self._trigfunc(0) != 0:
baseseries -= 1
baseseries = baseseries.replace(Pow, lambda t, n: t**n/n, simultaneous=False)
if self._trigfunc(0) != 0:
baseseries += EulerGamma + log(x)
return baseseries.subs(x, self.args[0])._eval_nseries(x, n, logx)
class Si(TrigonometricIntegral):
r"""
Sine integral.
Explanation
===========
This function is defined by
.. math:: \operatorname{Si}(z) = \int_0^z \frac{\sin{t}}{t} \mathrm{d}t.
It is an entire function.
Examples
========
>>> from sympy import Si
>>> from sympy.abc import z
The sine integral is an antiderivative of $sin(z)/z$:
>>> Si(z).diff(z)
sin(z)/z
It is unbranched:
>>> from sympy import exp_polar, I, pi
>>> Si(z*exp_polar(2*I*pi))
Si(z)
Sine integral behaves much like ordinary sine under multiplication by ``I``:
>>> Si(I*z)
I*Shi(z)
>>> Si(-z)
-Si(z)
It can also be expressed in terms of exponential integrals, but beware
that the latter is branched:
>>> from sympy import expint
>>> Si(z).rewrite(expint)
-I*(-expint(1, z*exp_polar(-I*pi/2))/2 +
expint(1, z*exp_polar(I*pi/2))/2) + pi/2
It can be rewritten in the form of sinc function (by definition):
>>> from sympy import sinc
>>> Si(z).rewrite(sinc)
Integral(sinc(t), (t, 0, z))
See Also
========
Ci: Cosine integral.
Shi: Hyperbolic sine integral.
Chi: Hyperbolic cosine integral.
Ei: Exponential integral.
expint: Generalised exponential integral.
sinc: unnormalized sinc function
E1: Special case of the generalised exponential integral.
li: Logarithmic integral.
Li: Offset logarithmic integral.
References
==========
.. [1] https://en.wikipedia.org/wiki/Trigonometric_integral
"""
_trigfunc = sin
_atzero = S.Zero
@classmethod
def _atinf(cls):
return pi*S.Half
@classmethod
def _atneginf(cls):
return -pi*S.Half
@classmethod
def _minusfactor(cls, z):
return -Si(z)
@classmethod
def _Ifactor(cls, z, sign):
return I*Shi(z)*sign
def _eval_rewrite_as_expint(self, z, **kwargs):
# XXX should we polarify z?
return pi/2 + (E1(polar_lift(I)*z) - E1(polar_lift(-I)*z))/2/I
def _eval_rewrite_as_sinc(self, z, **kwargs):
from sympy import Integral
t = Symbol('t', Dummy=True)
return Integral(sinc(t), (t, 0, z))
def _eval_aseries(self, n, args0, x, logx):
from sympy.series.order import Order
point = args0[0]
# Expansion at oo
if point is S.Infinity:
z = self.args[0]
p = [(-1)**k * factorial(2*k) / z**(2*k)
for k in range(0, int((n - 1)/2))] + [Order(1/z**n, x)]
q = [(-1)**k * factorial(2*k + 1) / z**(2*k + 1)
for k in range(0, int(n/2) - 1)] + [Order(1/z**n, x)]
return pi/2 - (cos(z)/z)*Add(*p) - (sin(z)/z)*Add(*q)
# All other points are not handled
return super(Si, self)._eval_aseries(n, args0, x, logx)
def _eval_is_zero(self):
z = self.args[0]
if z.is_zero:
return True
def _sage_(self):
import sage.all as sage
return sage.sin_integral(self.args[0]._sage_())
class Ci(TrigonometricIntegral):
r"""
Cosine integral.
Explanation
===========
This function is defined for positive $x$ by
.. math:: \operatorname{Ci}(x) = \gamma + \log{x}
+ \int_0^x \frac{\cos{t} - 1}{t} \mathrm{d}t
= -\int_x^\infty \frac{\cos{t}}{t} \mathrm{d}t,
where $\gamma$ is the Euler-Mascheroni constant.
We have
.. math:: \operatorname{Ci}(z) =
-\frac{\operatorname{E}_1\left(e^{i\pi/2} z\right)
+ \operatorname{E}_1\left(e^{-i \pi/2} z\right)}{2}
which holds for all polar $z$ and thus provides an analytic
continuation to the Riemann surface of the logarithm.
The formula also holds as stated
for $z \in \mathbb{C}$ with $\Re(z) > 0$.
By lifting to the principal branch, we obtain an analytic function on the
cut complex plane.
Examples
========
>>> from sympy import Ci
>>> from sympy.abc import z
The cosine integral is a primitive of $\cos(z)/z$:
>>> Ci(z).diff(z)
cos(z)/z
It has a logarithmic branch point at the origin:
>>> from sympy import exp_polar, I, pi
>>> Ci(z*exp_polar(2*I*pi))
Ci(z) + 2*I*pi
The cosine integral behaves somewhat like ordinary $\cos$ under
multiplication by $i$:
>>> from sympy import polar_lift
>>> Ci(polar_lift(I)*z)
Chi(z) + I*pi/2
>>> Ci(polar_lift(-1)*z)
Ci(z) + I*pi
It can also be expressed in terms of exponential integrals:
>>> from sympy import expint
>>> Ci(z).rewrite(expint)
-expint(1, z*exp_polar(-I*pi/2))/2 - expint(1, z*exp_polar(I*pi/2))/2
See Also
========
Si: Sine integral.
Shi: Hyperbolic sine integral.
Chi: Hyperbolic cosine integral.
Ei: Exponential integral.
expint: Generalised exponential integral.
E1: Special case of the generalised exponential integral.
li: Logarithmic integral.
Li: Offset logarithmic integral.
References
==========
.. [1] https://en.wikipedia.org/wiki/Trigonometric_integral
"""
_trigfunc = cos
_atzero = S.ComplexInfinity
@classmethod
def _atinf(cls):
return S.Zero
@classmethod
def _atneginf(cls):
return I*pi
@classmethod
def _minusfactor(cls, z):
return Ci(z) + I*pi
@classmethod
def _Ifactor(cls, z, sign):
return Chi(z) + I*pi/2*sign
def _eval_rewrite_as_expint(self, z, **kwargs):
return -(E1(polar_lift(I)*z) + E1(polar_lift(-I)*z))/2
def _eval_as_leading_term(self, x, logx=None, cdir=0):
arg = self.args[0].as_leading_term(x, logx=logx, cdir=cdir)
arg0 = arg.subs(x, 0)
if arg0 is S.NaN:
arg0 = arg.limit(x, 0, dir='-' if re(cdir).is_negative else '+')
if arg0.is_zero:
return S.EulerGamma
elif arg0.is_finite:
return self.func(arg0)
else:
return self
def _eval_aseries(self, n, args0, x, logx):
from sympy.series.order import Order
point = args0[0]
# Expansion at oo
if point is S.Infinity:
z = self.args[0]
p = [(-1)**k * factorial(2*k) / z**(2*k)
for k in range(0, int((n - 1)/2))] + [Order(1/z**n, x)]
q = [(-1)**k * factorial(2*k + 1) / z**(2*k + 1)
for k in range(0, int(n/2) - 1)] + [Order(1/z**n, x)]
return (sin(z)/z)*Add(*p) - (cos(z)/z)*Add(*q)
# All other points are not handled
return super(Ci, self)._eval_aseries(n, args0, x, logx)
def _sage_(self):
import sage.all as sage
return sage.cos_integral(self.args[0]._sage_())
class Shi(TrigonometricIntegral):
r"""
Sinh integral.
Explanation
===========
This function is defined by
.. math:: \operatorname{Shi}(z) = \int_0^z \frac{\sinh{t}}{t} \mathrm{d}t.
It is an entire function.
Examples
========
>>> from sympy import Shi
>>> from sympy.abc import z
The Sinh integral is a primitive of $\sinh(z)/z$:
>>> Shi(z).diff(z)
sinh(z)/z
It is unbranched:
>>> from sympy import exp_polar, I, pi
>>> Shi(z*exp_polar(2*I*pi))
Shi(z)
The $\sinh$ integral behaves much like ordinary $\sinh$ under
multiplication by $i$:
>>> Shi(I*z)
I*Si(z)
>>> Shi(-z)
-Shi(z)
It can also be expressed in terms of exponential integrals, but beware
that the latter is branched:
>>> from sympy import expint
>>> Shi(z).rewrite(expint)
expint(1, z)/2 - expint(1, z*exp_polar(I*pi))/2 - I*pi/2
See Also
========
Si: Sine integral.
Ci: Cosine integral.
Chi: Hyperbolic cosine integral.
Ei: Exponential integral.
expint: Generalised exponential integral.
E1: Special case of the generalised exponential integral.
li: Logarithmic integral.
Li: Offset logarithmic integral.
References
==========
.. [1] https://en.wikipedia.org/wiki/Trigonometric_integral
"""
_trigfunc = sinh
_atzero = S.Zero
@classmethod
def _atinf(cls):
return S.Infinity
@classmethod
def _atneginf(cls):
return S.NegativeInfinity
@classmethod
def _minusfactor(cls, z):
return -Shi(z)
@classmethod
def _Ifactor(cls, z, sign):
return I*Si(z)*sign
def _eval_rewrite_as_expint(self, z, **kwargs):
from sympy import exp_polar
# XXX should we polarify z?
return (E1(z) - E1(exp_polar(I*pi)*z))/2 - I*pi/2
def _eval_is_zero(self):
z = self.args[0]
if z.is_zero:
return True
def _eval_as_leading_term(self, x, logx=None, cdir=0):
arg = self.args[0].as_leading_term(x)
arg0 = arg.subs(x, 0)
if arg0 is S.NaN:
arg0 = arg.limit(x, 0, dir='-' if re(cdir).is_negative else '+')
if arg0.is_zero:
return arg
elif not arg0.is_infinite:
return self.func(arg0)
elif arg0.is_infinite:
return -pi*S.ImaginiryUnit/2
else:
return self
def _sage_(self):
import sage.all as sage
return sage.sinh_integral(self.args[0]._sage_())
class Chi(TrigonometricIntegral):
r"""
Cosh integral.
Explanation
===========
This function is defined for positive $x$ by
.. math:: \operatorname{Chi}(x) = \gamma + \log{x}
+ \int_0^x \frac{\cosh{t} - 1}{t} \mathrm{d}t,
where $\gamma$ is the Euler-Mascheroni constant.
We have
.. math:: \operatorname{Chi}(z) = \operatorname{Ci}\left(e^{i \pi/2}z\right)
- i\frac{\pi}{2},
which holds for all polar $z$ and thus provides an analytic
continuation to the Riemann surface of the logarithm.
By lifting to the principal branch we obtain an analytic function on the
cut complex plane.
Examples
========
>>> from sympy import Chi
>>> from sympy.abc import z
The $\cosh$ integral is a primitive of $\cosh(z)/z$:
>>> Chi(z).diff(z)
cosh(z)/z
It has a logarithmic branch point at the origin:
>>> from sympy import exp_polar, I, pi
>>> Chi(z*exp_polar(2*I*pi))
Chi(z) + 2*I*pi
The $\cosh$ integral behaves somewhat like ordinary $\cosh$ under
multiplication by $i$:
>>> from sympy import polar_lift
>>> Chi(polar_lift(I)*z)
Ci(z) + I*pi/2
>>> Chi(polar_lift(-1)*z)
Chi(z) + I*pi
It can also be expressed in terms of exponential integrals:
>>> from sympy import expint
>>> Chi(z).rewrite(expint)
-expint(1, z)/2 - expint(1, z*exp_polar(I*pi))/2 - I*pi/2
See Also
========
Si: Sine integral.
Ci: Cosine integral.
Shi: Hyperbolic sine integral.
Ei: Exponential integral.
expint: Generalised exponential integral.
E1: Special case of the generalised exponential integral.
li: Logarithmic integral.
Li: Offset logarithmic integral.
References
==========
.. [1] https://en.wikipedia.org/wiki/Trigonometric_integral
"""
_trigfunc = cosh
_atzero = S.ComplexInfinity
@classmethod
def _atinf(cls):
return S.Infinity
@classmethod
def _atneginf(cls):
return S.Infinity
@classmethod
def _minusfactor(cls, z):
return Chi(z) + I*pi
@classmethod
def _Ifactor(cls, z, sign):
return Ci(z) + I*pi/2*sign
def _eval_rewrite_as_expint(self, z, **kwargs):
from sympy import exp_polar
return -I*pi/2 - (E1(z) + E1(exp_polar(I*pi)*z))/2
def _eval_as_leading_term(self, x, logx=None, cdir=0):
arg = self.args[0].as_leading_term(x, logx=logx, cdir=cdir)
arg0 = arg.subs(x, 0)
if arg0 is S.NaN:
arg0 = arg.limit(x, 0, dir='-' if re(cdir).is_negative else '+')
if arg0.is_zero:
return S.EulerGamma
elif arg0.is_finite:
return self.func(arg0)
else:
return self
def _sage_(self):
import sage.all as sage
return sage.cosh_integral(self.args[0]._sage_())
###############################################################################
#################### FRESNEL INTEGRALS ########################################
###############################################################################
class FresnelIntegral(Function):
""" Base class for the Fresnel integrals."""
unbranched = True
@classmethod
def eval(cls, z):
# Values at positive infinities signs
# if any were extracted automatically
if z is S.Infinity:
return S.Half
# Value at zero
if z.is_zero:
return S.Zero
# Try to pull out factors of -1 and I
prefact = S.One
newarg = z
changed = False
nz = newarg.extract_multiplicatively(-1)
if nz is not None:
prefact = -prefact
newarg = nz
changed = True
nz = newarg.extract_multiplicatively(I)
if nz is not None:
prefact = cls._sign*I*prefact
newarg = nz
changed = True
if changed:
return prefact*cls(newarg)
def fdiff(self, argindex=1):
if argindex == 1:
return self._trigfunc(S.Half*pi*self.args[0]**2)
else:
raise ArgumentIndexError(self, argindex)
def _eval_is_extended_real(self):
return self.args[0].is_extended_real
_eval_is_finite = _eval_is_extended_real
def _eval_is_zero(self):
z = self.args[0]
if z.is_zero:
return True
def _eval_conjugate(self):
return self.func(self.args[0].conjugate())
as_real_imag = real_to_real_as_real_imag
class fresnels(FresnelIntegral):
r"""
Fresnel integral S.
Explanation
===========
This function is defined by
.. math:: \operatorname{S}(z) = \int_0^z \sin{\frac{\pi}{2} t^2} \mathrm{d}t.
It is an entire function.
Examples
========
>>> from sympy import I, oo, fresnels
>>> from sympy.abc import z
Several special values are known:
>>> fresnels(0)
0
>>> fresnels(oo)
1/2
>>> fresnels(-oo)
-1/2
>>> fresnels(I*oo)
-I/2
>>> fresnels(-I*oo)
I/2
In general one can pull out factors of -1 and $i$ from the argument:
>>> fresnels(-z)
-fresnels(z)
>>> fresnels(I*z)
-I*fresnels(z)
The Fresnel S integral obeys the mirror symmetry
$\overline{S(z)} = S(\bar{z})$:
>>> from sympy import conjugate
>>> conjugate(fresnels(z))
fresnels(conjugate(z))
Differentiation with respect to $z$ is supported:
>>> from sympy import diff
>>> diff(fresnels(z), z)
sin(pi*z**2/2)
Defining the Fresnel functions via an integral:
>>> from sympy import integrate, pi, sin, expand_func
>>> integrate(sin(pi*z**2/2), z)
3*fresnels(z)*gamma(3/4)/(4*gamma(7/4))
>>> expand_func(integrate(sin(pi*z**2/2), z))
fresnels(z)
We can numerically evaluate the Fresnel integral to arbitrary precision
on the whole complex plane:
>>> fresnels(2).evalf(30)
0.343415678363698242195300815958
>>> fresnels(-2*I).evalf(30)
0.343415678363698242195300815958*I
See Also
========
fresnelc: Fresnel cosine integral.
References
==========
.. [1] https://en.wikipedia.org/wiki/Fresnel_integral
.. [2] http://dlmf.nist.gov/7
.. [3] http://mathworld.wolfram.com/FresnelIntegrals.html
.. [4] http://functions.wolfram.com/GammaBetaErf/FresnelS
.. [5] The converging factors for the fresnel integrals
by John W. Wrench Jr. and Vicki Alley
"""
_trigfunc = sin
_sign = -S.One
@staticmethod
@cacheit
def taylor_term(n, x, *previous_terms):
if n < 0:
return S.Zero
else:
x = sympify(x)
if len(previous_terms) > 1:
p = previous_terms[-1]
return (-pi**2*x**4*(4*n - 1)/(8*n*(2*n + 1)*(4*n + 3))) * p
else:
return x**3 * (-x**4)**n * (S(2)**(-2*n - 1)*pi**(2*n + 1)) / ((4*n + 3)*factorial(2*n + 1))
def _eval_rewrite_as_erf(self, z, **kwargs):
return (S.One + I)/4 * (erf((S.One + I)/2*sqrt(pi)*z) - I*erf((S.One - I)/2*sqrt(pi)*z))
def _eval_rewrite_as_hyper(self, z, **kwargs):
return pi*z**3/6 * hyper([Rational(3, 4)], [Rational(3, 2), Rational(7, 4)], -pi**2*z**4/16)
def _eval_rewrite_as_meijerg(self, z, **kwargs):
return (pi*z**Rational(9, 4) / (sqrt(2)*(z**2)**Rational(3, 4)*(-z)**Rational(3, 4))
* meijerg([], [1], [Rational(3, 4)], [Rational(1, 4), 0], -pi**2*z**4/16))
def _eval_as_leading_term(self, x, logx=None, cdir=0):
from sympy.series.order import Order
arg = self.args[0].as_leading_term(x, logx=logx, cdir=cdir)
arg0 = arg.subs(x, 0)
if arg0 is S.ComplexInfinity:
arg0 = arg.limit(x, 0, dir='-' if re(cdir).is_negative else '+')
if arg0.is_zero:
return pi*arg**3/6
elif arg0 in [S.Infinity, S.NegativeInfinity]:
s = 1 if arg0 is S.Infinity else -1
return s*S.Half + Order(x, x)
else:
return self.func(arg0)
def _eval_aseries(self, n, args0, x, logx):
from sympy import Order
point = args0[0]
# Expansion at oo and -oo
if point in [S.Infinity, -S.Infinity]:
z = self.args[0]
# expansion of S(x) = S1(x*sqrt(pi/2)), see reference[5] page 1-8
# as only real infinities are dealt with, sin and cos are O(1)
p = [(-1)**k * factorial(4*k + 1) /
(2**(2*k + 2) * z**(4*k + 3) * 2**(2*k)*factorial(2*k))
for k in range(0, n) if 4*k + 3 < n]
q = [1/(2*z)] + [(-1)**k * factorial(4*k - 1) /
(2**(2*k + 1) * z**(4*k + 1) * 2**(2*k - 1)*factorial(2*k - 1))
for k in range(1, n) if 4*k + 1 < n]
p = [-sqrt(2/pi)*t for t in p]
q = [-sqrt(2/pi)*t for t in q]
s = 1 if point is S.Infinity else -1
# The expansion at oo is 1/2 + some odd powers of z
# To get the expansion at -oo, replace z by -z and flip the sign
# The result -1/2 + the same odd powers of z as before.
return s*S.Half + (sin(z**2)*Add(*p) + cos(z**2)*Add(*q)
).subs(x, sqrt(2/pi)*x) + Order(1/z**n, x)
# All other points are not handled
return super()._eval_aseries(n, args0, x, logx)
class fresnelc(FresnelIntegral):
r"""
Fresnel integral C.
Explanation
===========
This function is defined by
.. math:: \operatorname{C}(z) = \int_0^z \cos{\frac{\pi}{2} t^2} \mathrm{d}t.
It is an entire function.
Examples
========
>>> from sympy import I, oo, fresnelc
>>> from sympy.abc import z
Several special values are known:
>>> fresnelc(0)
0
>>> fresnelc(oo)
1/2
>>> fresnelc(-oo)
-1/2
>>> fresnelc(I*oo)
I/2
>>> fresnelc(-I*oo)
-I/2
In general one can pull out factors of -1 and $i$ from the argument:
>>> fresnelc(-z)
-fresnelc(z)
>>> fresnelc(I*z)
I*fresnelc(z)
The Fresnel C integral obeys the mirror symmetry
$\overline{C(z)} = C(\bar{z})$:
>>> from sympy import conjugate
>>> conjugate(fresnelc(z))
fresnelc(conjugate(z))
Differentiation with respect to $z$ is supported:
>>> from sympy import diff
>>> diff(fresnelc(z), z)
cos(pi*z**2/2)
Defining the Fresnel functions via an integral:
>>> from sympy import integrate, pi, cos, expand_func
>>> integrate(cos(pi*z**2/2), z)
fresnelc(z)*gamma(1/4)/(4*gamma(5/4))
>>> expand_func(integrate(cos(pi*z**2/2), z))
fresnelc(z)
We can numerically evaluate the Fresnel integral to arbitrary precision
on the whole complex plane:
>>> fresnelc(2).evalf(30)
0.488253406075340754500223503357
>>> fresnelc(-2*I).evalf(30)
-0.488253406075340754500223503357*I
See Also
========
fresnels: Fresnel sine integral.
References
==========
.. [1] https://en.wikipedia.org/wiki/Fresnel_integral
.. [2] http://dlmf.nist.gov/7
.. [3] http://mathworld.wolfram.com/FresnelIntegrals.html
.. [4] http://functions.wolfram.com/GammaBetaErf/FresnelC
.. [5] The converging factors for the fresnel integrals
by John W. Wrench Jr. and Vicki Alley
"""
_trigfunc = cos
_sign = S.One
@staticmethod
@cacheit
def taylor_term(n, x, *previous_terms):
if n < 0:
return S.Zero
else:
x = sympify(x)
if len(previous_terms) > 1:
p = previous_terms[-1]
return (-pi**2*x**4*(4*n - 3)/(8*n*(2*n - 1)*(4*n + 1))) * p
else:
return x * (-x**4)**n * (S(2)**(-2*n)*pi**(2*n)) / ((4*n + 1)*factorial(2*n))
def _eval_rewrite_as_erf(self, z, **kwargs):
return (S.One - I)/4 * (erf((S.One + I)/2*sqrt(pi)*z) + I*erf((S.One - I)/2*sqrt(pi)*z))
def _eval_rewrite_as_hyper(self, z, **kwargs):
return z * hyper([Rational(1, 4)], [S.Half, Rational(5, 4)], -pi**2*z**4/16)
def _eval_rewrite_as_meijerg(self, z, **kwargs):
return (pi*z**Rational(3, 4) / (sqrt(2)*root(z**2, 4)*root(-z, 4))
* meijerg([], [1], [Rational(1, 4)], [Rational(3, 4), 0], -pi**2*z**4/16))
def _eval_as_leading_term(self, x, logx=None, cdir=0):
from sympy import Order
arg = self.args[0].as_leading_term(x, logx=logx, cdir=cdir)
arg0 = arg.subs(x, 0)
if arg0 is S.ComplexInfinity:
arg0 = arg.limit(x, 0, dir='-' if re(cdir).is_negative else '+')
if arg0.is_zero:
return arg
elif arg0 in [S.Infinity, S.NegativeInfinity]:
s = 1 if arg0 is S.Infinity else -1
return s*S.Half + Order(x, x)
else:
return self.func(arg0)
def _eval_aseries(self, n, args0, x, logx):
from sympy import Order
point = args0[0]
# Expansion at oo
if point in [S.Infinity, -S.Infinity]:
z = self.args[0]
# expansion of C(x) = C1(x*sqrt(pi/2)), see reference[5] page 1-8
# as only real infinities are dealt with, sin and cos are O(1)
p = [(-1)**k * factorial(4*k + 1) /
(2**(2*k + 2) * z**(4*k + 3) * 2**(2*k)*factorial(2*k))
for k in range(0, n) if 4*k + 3 < n]
q = [1/(2*z)] + [(-1)**k * factorial(4*k - 1) /
(2**(2*k + 1) * z**(4*k + 1) * 2**(2*k - 1)*factorial(2*k - 1))
for k in range(1, n) if 4*k + 1 < n]
p = [-sqrt(2/pi)*t for t in p]
q = [ sqrt(2/pi)*t for t in q]
s = 1 if point is S.Infinity else -1
# The expansion at oo is 1/2 + some odd powers of z
# To get the expansion at -oo, replace z by -z and flip the sign
# The result -1/2 + the same odd powers of z as before.
return s*S.Half + (cos(z**2)*Add(*p) + sin(z**2)*Add(*q)
).subs(x, sqrt(2/pi)*x) + Order(1/z**n, x)
# All other points are not handled
return super()._eval_aseries(n, args0, x, logx)
###############################################################################
#################### HELPER FUNCTIONS #########################################
###############################################################################
class _erfs(Function):
"""
Helper function to make the $\\mathrm{erf}(z)$ function
tractable for the Gruntz algorithm.
"""
@classmethod
def eval(cls, arg):
if arg.is_zero:
return S.One
def _eval_aseries(self, n, args0, x, logx):
from sympy import Order
point = args0[0]
# Expansion at oo
if point is S.Infinity:
z = self.args[0]
l = [ 1/sqrt(S.Pi) * factorial(2*k)*(-S(
4))**(-k)/factorial(k) * (1/z)**(2*k + 1) for k in range(0, n) ]
o = Order(1/z**(2*n + 1), x)
# It is very inefficient to first add the order and then do the nseries
return (Add(*l))._eval_nseries(x, n, logx) + o
# Expansion at I*oo
t = point.extract_multiplicatively(S.ImaginaryUnit)
if t is S.Infinity:
z = self.args[0]
# TODO: is the series really correct?
l = [ 1/sqrt(S.Pi) * factorial(2*k)*(-S(
4))**(-k)/factorial(k) * (1/z)**(2*k + 1) for k in range(0, n) ]
o = Order(1/z**(2*n + 1), x)
# It is very inefficient to first add the order and then do the nseries
return (Add(*l))._eval_nseries(x, n, logx) + o
# All other points are not handled
return super()._eval_aseries(n, args0, x, logx)
def fdiff(self, argindex=1):
if argindex == 1:
z = self.args[0]
return -2/sqrt(S.Pi) + 2*z*_erfs(z)
else:
raise ArgumentIndexError(self, argindex)
def _eval_rewrite_as_intractable(self, z, **kwargs):
return (S.One - erf(z))*exp(z**2)
class _eis(Function):
"""
Helper function to make the $\\mathrm{Ei}(z)$ and $\\mathrm{li}(z)$
functions tractable for the Gruntz algorithm.
"""
def _eval_aseries(self, n, args0, x, logx):
from sympy import Order
if args0[0] != S.Infinity:
return super(_erfs, self)._eval_aseries(n, args0, x, logx)
z = self.args[0]
l = [ factorial(k) * (1/z)**(k + 1) for k in range(0, n) ]
o = Order(1/z**(n + 1), x)
# It is very inefficient to first add the order and then do the nseries
return (Add(*l))._eval_nseries(x, n, logx) + o
def fdiff(self, argindex=1):
if argindex == 1:
z = self.args[0]
return S.One / z - _eis(z)
else:
raise ArgumentIndexError(self, argindex)
def _eval_rewrite_as_intractable(self, z, **kwargs):
return exp(-z)*Ei(z)
def _eval_as_leading_term(self, x, logx=None, cdir=0):
x0 = self.args[0].limit(x, 0)
if x0.is_zero:
f = self._eval_rewrite_as_intractable(*self.args)
return f._eval_as_leading_term(x, logx=logx, cdir=cdir)
return super()._eval_as_leading_term(x, logx=logx, cdir=cdir)
def _eval_nseries(self, x, n, logx, cdir=0):
x0 = self.args[0].limit(x, 0)
if x0.is_zero:
f = self._eval_rewrite_as_intractable(*self.args)
return f._eval_nseries(x, n, logx)
return super()._eval_nseries(x, n, logx)
|
c2a289f5064642da771230c78cbb3d6c747c96248b8f2eef46db50a6af5c036b | from sympy import (symbols, Symbol, nan, oo, zoo, I, sinh, sin, pi, atan,
acos, Rational, sqrt, asin, acot, coth, E, S, tan, tanh, cos,
cosh, atan2, exp, log, asinh, acoth, atanh, O, cancel, Matrix, re, im,
Float, Pow, gcd, sec, csc, cot, diff, simplify, Heaviside, arg,
conjugate, series, FiniteSet, asec, acsc, Mul, sinc, jn,
AccumBounds, Interval, ImageSet, Lambda, besselj, Add, limit)
from sympy.core.expr import unchanged
from sympy.core.function import ArgumentIndexError
from sympy.core.relational import Ne, Eq
from sympy.functions.elementary.piecewise import Piecewise
from sympy.sets.setexpr import SetExpr
from sympy.testing.pytest import XFAIL, slow, raises
x, y, z = symbols('x y z')
r = Symbol('r', real=True)
k, m = symbols('k m', integer=True)
p = Symbol('p', positive=True)
n = Symbol('n', negative=True)
np = Symbol('p', nonpositive=True)
nn = Symbol('n', nonnegative=True)
nz = Symbol('nz', nonzero=True)
ep = Symbol('ep', extended_positive=True)
en = Symbol('en', extended_negative=True)
enp = Symbol('ep', extended_nonpositive=True)
enn = Symbol('en', extended_nonnegative=True)
enz = Symbol('enz', extended_nonzero=True)
a = Symbol('a', algebraic=True)
na = Symbol('na', nonzero=True, algebraic=True)
def test_sin():
x, y = symbols('x y')
assert sin.nargs == FiniteSet(1)
assert sin(nan) is nan
assert sin(zoo) is nan
assert sin(oo) == AccumBounds(-1, 1)
assert sin(oo) - sin(oo) == AccumBounds(-2, 2)
assert sin(oo*I) == oo*I
assert sin(-oo*I) == -oo*I
assert 0*sin(oo) is S.Zero
assert 0/sin(oo) is S.Zero
assert 0 + sin(oo) == AccumBounds(-1, 1)
assert 5 + sin(oo) == AccumBounds(4, 6)
assert sin(0) == 0
assert sin(asin(x)) == x
assert sin(atan(x)) == x / sqrt(1 + x**2)
assert sin(acos(x)) == sqrt(1 - x**2)
assert sin(acot(x)) == 1 / (sqrt(1 + 1 / x**2) * x)
assert sin(acsc(x)) == 1 / x
assert sin(asec(x)) == sqrt(1 - 1 / x**2)
assert sin(atan2(y, x)) == y / sqrt(x**2 + y**2)
assert sin(pi*I) == sinh(pi)*I
assert sin(-pi*I) == -sinh(pi)*I
assert sin(-2*I) == -sinh(2)*I
assert sin(pi) == 0
assert sin(-pi) == 0
assert sin(2*pi) == 0
assert sin(-2*pi) == 0
assert sin(-3*10**73*pi) == 0
assert sin(7*10**103*pi) == 0
assert sin(pi/2) == 1
assert sin(-pi/2) == -1
assert sin(pi*Rational(5, 2)) == 1
assert sin(pi*Rational(7, 2)) == -1
ne = symbols('ne', integer=True, even=False)
e = symbols('e', even=True)
assert sin(pi*ne/2) == (-1)**(ne/2 - S.Half)
assert sin(pi*k/2).func == sin
assert sin(pi*e/2) == 0
assert sin(pi*k) == 0
assert sin(pi*k).subs(k, 3) == sin(pi*k/2).subs(k, 6) # issue 8298
assert sin(pi/3) == S.Half*sqrt(3)
assert sin(pi*Rational(-2, 3)) == Rational(-1, 2)*sqrt(3)
assert sin(pi/4) == S.Half*sqrt(2)
assert sin(-pi/4) == Rational(-1, 2)*sqrt(2)
assert sin(pi*Rational(17, 4)) == S.Half*sqrt(2)
assert sin(pi*Rational(-3, 4)) == Rational(-1, 2)*sqrt(2)
assert sin(pi/6) == S.Half
assert sin(-pi/6) == Rational(-1, 2)
assert sin(pi*Rational(7, 6)) == Rational(-1, 2)
assert sin(pi*Rational(-5, 6)) == Rational(-1, 2)
assert sin(pi*Rational(1, 5)) == sqrt((5 - sqrt(5)) / 8)
assert sin(pi*Rational(2, 5)) == sqrt((5 + sqrt(5)) / 8)
assert sin(pi*Rational(3, 5)) == sin(pi*Rational(2, 5))
assert sin(pi*Rational(4, 5)) == sin(pi*Rational(1, 5))
assert sin(pi*Rational(6, 5)) == -sin(pi*Rational(1, 5))
assert sin(pi*Rational(8, 5)) == -sin(pi*Rational(2, 5))
assert sin(pi*Rational(-1273, 5)) == -sin(pi*Rational(2, 5))
assert sin(pi/8) == sqrt((2 - sqrt(2))/4)
assert sin(pi/10) == Rational(-1, 4) + sqrt(5)/4
assert sin(pi/12) == -sqrt(2)/4 + sqrt(6)/4
assert sin(pi*Rational(5, 12)) == sqrt(2)/4 + sqrt(6)/4
assert sin(pi*Rational(-7, 12)) == -sqrt(2)/4 - sqrt(6)/4
assert sin(pi*Rational(-11, 12)) == sqrt(2)/4 - sqrt(6)/4
assert sin(pi*Rational(104, 105)) == sin(pi/105)
assert sin(pi*Rational(106, 105)) == -sin(pi/105)
assert sin(pi*Rational(-104, 105)) == -sin(pi/105)
assert sin(pi*Rational(-106, 105)) == sin(pi/105)
assert sin(x*I) == sinh(x)*I
assert sin(k*pi) == 0
assert sin(17*k*pi) == 0
assert sin(2*k*pi + 4) == sin(4)
assert sin(2*k*pi + m*pi + 1) == (-1)**(m + 2*k)*sin(1)
assert sin(k*pi*I) == sinh(k*pi)*I
assert sin(r).is_real is True
assert sin(0, evaluate=False).is_algebraic
assert sin(a).is_algebraic is None
assert sin(na).is_algebraic is False
q = Symbol('q', rational=True)
assert sin(pi*q).is_algebraic
qn = Symbol('qn', rational=True, nonzero=True)
assert sin(qn).is_rational is False
assert sin(q).is_rational is None # issue 8653
assert isinstance(sin( re(x) - im(y)), sin) is True
assert isinstance(sin(-re(x) + im(y)), sin) is False
assert sin(SetExpr(Interval(0, 1))) == SetExpr(ImageSet(Lambda(x, sin(x)),
Interval(0, 1)))
for d in list(range(1, 22)) + [60, 85]:
for n in range(0, d*2 + 1):
x = n*pi/d
e = abs( float(sin(x)) - sin(float(x)) )
assert e < 1e-12
assert sin(0, evaluate=False).is_zero is True
assert sin(k*pi, evaluate=False).is_zero is None
assert sin(Add(1, -1, evaluate=False), evaluate=False).is_zero is True
def test_sin_cos():
for d in [1, 2, 3, 4, 5, 6, 10, 12, 15, 20, 24, 30, 40, 60, 120]: # list is not exhaustive...
for n in range(-2*d, d*2):
x = n*pi/d
assert sin(x + pi/2) == cos(x), "fails for %d*pi/%d" % (n, d)
assert sin(x - pi/2) == -cos(x), "fails for %d*pi/%d" % (n, d)
assert sin(x) == cos(x - pi/2), "fails for %d*pi/%d" % (n, d)
assert -sin(x) == cos(x + pi/2), "fails for %d*pi/%d" % (n, d)
def test_sin_series():
assert sin(x).series(x, 0, 9) == \
x - x**3/6 + x**5/120 - x**7/5040 + O(x**9)
def test_sin_rewrite():
assert sin(x).rewrite(exp) == -I*(exp(I*x) - exp(-I*x))/2
assert sin(x).rewrite(tan) == 2*tan(x/2)/(1 + tan(x/2)**2)
assert sin(x).rewrite(cot) == 2*cot(x/2)/(1 + cot(x/2)**2)
assert sin(sinh(x)).rewrite(
exp).subs(x, 3).n() == sin(x).rewrite(exp).subs(x, sinh(3)).n()
assert sin(cosh(x)).rewrite(
exp).subs(x, 3).n() == sin(x).rewrite(exp).subs(x, cosh(3)).n()
assert sin(tanh(x)).rewrite(
exp).subs(x, 3).n() == sin(x).rewrite(exp).subs(x, tanh(3)).n()
assert sin(coth(x)).rewrite(
exp).subs(x, 3).n() == sin(x).rewrite(exp).subs(x, coth(3)).n()
assert sin(sin(x)).rewrite(
exp).subs(x, 3).n() == sin(x).rewrite(exp).subs(x, sin(3)).n()
assert sin(cos(x)).rewrite(
exp).subs(x, 3).n() == sin(x).rewrite(exp).subs(x, cos(3)).n()
assert sin(tan(x)).rewrite(
exp).subs(x, 3).n() == sin(x).rewrite(exp).subs(x, tan(3)).n()
assert sin(cot(x)).rewrite(
exp).subs(x, 3).n() == sin(x).rewrite(exp).subs(x, cot(3)).n()
assert sin(log(x)).rewrite(Pow) == I*x**-I / 2 - I*x**I /2
assert sin(x).rewrite(csc) == 1/csc(x)
assert sin(x).rewrite(cos) == cos(x - pi / 2, evaluate=False)
assert sin(x).rewrite(sec) == 1 / sec(x - pi / 2, evaluate=False)
assert sin(cos(x)).rewrite(Pow) == sin(cos(x))
def _test_extrig(f, i, e):
from sympy.core.expr import unchanged
from sympy.core.function import expand_trig
assert unchanged(f, i)
assert expand_trig(f(i)) == f(i)
# testing directly instead of with .expand(trig=True)
# because the other expansions undo the unevaluated Mul
assert expand_trig(f(Mul(i, 1, evaluate=False))) == e
assert abs(f(i) - e).n() < 1e-10
def test_sin_expansion():
# Note: these formulas are not unique. The ones here come from the
# Chebyshev formulas.
assert sin(x + y).expand(trig=True) == sin(x)*cos(y) + cos(x)*sin(y)
assert sin(x - y).expand(trig=True) == sin(x)*cos(y) - cos(x)*sin(y)
assert sin(y - x).expand(trig=True) == cos(x)*sin(y) - sin(x)*cos(y)
assert sin(2*x).expand(trig=True) == 2*sin(x)*cos(x)
assert sin(3*x).expand(trig=True) == -4*sin(x)**3 + 3*sin(x)
assert sin(4*x).expand(trig=True) == -8*sin(x)**3*cos(x) + 4*sin(x)*cos(x)
_test_extrig(sin, 2, 2*sin(1)*cos(1))
_test_extrig(sin, 3, -4*sin(1)**3 + 3*sin(1))
def test_sin_AccumBounds():
assert sin(AccumBounds(-oo, oo)) == AccumBounds(-1, 1)
assert sin(AccumBounds(0, oo)) == AccumBounds(-1, 1)
assert sin(AccumBounds(-oo, 0)) == AccumBounds(-1, 1)
assert sin(AccumBounds(0, 2*S.Pi)) == AccumBounds(-1, 1)
assert sin(AccumBounds(0, S.Pi*Rational(3, 4))) == AccumBounds(0, 1)
assert sin(AccumBounds(S.Pi*Rational(3, 4), S.Pi*Rational(7, 4))) == AccumBounds(-1, sin(S.Pi*Rational(3, 4)))
assert sin(AccumBounds(S.Pi/4, S.Pi/3)) == AccumBounds(sin(S.Pi/4), sin(S.Pi/3))
assert sin(AccumBounds(S.Pi*Rational(3, 4), S.Pi*Rational(5, 6))) == AccumBounds(sin(S.Pi*Rational(5, 6)), sin(S.Pi*Rational(3, 4)))
def test_sin_fdiff():
assert sin(x).fdiff() == cos(x)
raises(ArgumentIndexError, lambda: sin(x).fdiff(2))
def test_trig_symmetry():
assert sin(-x) == -sin(x)
assert cos(-x) == cos(x)
assert tan(-x) == -tan(x)
assert cot(-x) == -cot(x)
assert sin(x + pi) == -sin(x)
assert sin(x + 2*pi) == sin(x)
assert sin(x + 3*pi) == -sin(x)
assert sin(x + 4*pi) == sin(x)
assert sin(x - 5*pi) == -sin(x)
assert cos(x + pi) == -cos(x)
assert cos(x + 2*pi) == cos(x)
assert cos(x + 3*pi) == -cos(x)
assert cos(x + 4*pi) == cos(x)
assert cos(x - 5*pi) == -cos(x)
assert tan(x + pi) == tan(x)
assert tan(x - 3*pi) == tan(x)
assert cot(x + pi) == cot(x)
assert cot(x - 3*pi) == cot(x)
assert sin(pi/2 - x) == cos(x)
assert sin(pi*Rational(3, 2) - x) == -cos(x)
assert sin(pi*Rational(5, 2) - x) == cos(x)
assert cos(pi/2 - x) == sin(x)
assert cos(pi*Rational(3, 2) - x) == -sin(x)
assert cos(pi*Rational(5, 2) - x) == sin(x)
assert tan(pi/2 - x) == cot(x)
assert tan(pi*Rational(3, 2) - x) == cot(x)
assert tan(pi*Rational(5, 2) - x) == cot(x)
assert cot(pi/2 - x) == tan(x)
assert cot(pi*Rational(3, 2) - x) == tan(x)
assert cot(pi*Rational(5, 2) - x) == tan(x)
assert sin(pi/2 + x) == cos(x)
assert cos(pi/2 + x) == -sin(x)
assert tan(pi/2 + x) == -cot(x)
assert cot(pi/2 + x) == -tan(x)
def test_cos():
x, y = symbols('x y')
assert cos.nargs == FiniteSet(1)
assert cos(nan) is nan
assert cos(oo) == AccumBounds(-1, 1)
assert cos(oo) - cos(oo) == AccumBounds(-2, 2)
assert cos(oo*I) is oo
assert cos(-oo*I) is oo
assert cos(zoo) is nan
assert cos(0) == 1
assert cos(acos(x)) == x
assert cos(atan(x)) == 1 / sqrt(1 + x**2)
assert cos(asin(x)) == sqrt(1 - x**2)
assert cos(acot(x)) == 1 / sqrt(1 + 1 / x**2)
assert cos(acsc(x)) == sqrt(1 - 1 / x**2)
assert cos(asec(x)) == 1 / x
assert cos(atan2(y, x)) == x / sqrt(x**2 + y**2)
assert cos(pi*I) == cosh(pi)
assert cos(-pi*I) == cosh(pi)
assert cos(-2*I) == cosh(2)
assert cos(pi/2) == 0
assert cos(-pi/2) == 0
assert cos(pi/2) == 0
assert cos(-pi/2) == 0
assert cos((-3*10**73 + 1)*pi/2) == 0
assert cos((7*10**103 + 1)*pi/2) == 0
n = symbols('n', integer=True, even=False)
e = symbols('e', even=True)
assert cos(pi*n/2) == 0
assert cos(pi*e/2) == (-1)**(e/2)
assert cos(pi) == -1
assert cos(-pi) == -1
assert cos(2*pi) == 1
assert cos(5*pi) == -1
assert cos(8*pi) == 1
assert cos(pi/3) == S.Half
assert cos(pi*Rational(-2, 3)) == Rational(-1, 2)
assert cos(pi/4) == S.Half*sqrt(2)
assert cos(-pi/4) == S.Half*sqrt(2)
assert cos(pi*Rational(11, 4)) == Rational(-1, 2)*sqrt(2)
assert cos(pi*Rational(-3, 4)) == Rational(-1, 2)*sqrt(2)
assert cos(pi/6) == S.Half*sqrt(3)
assert cos(-pi/6) == S.Half*sqrt(3)
assert cos(pi*Rational(7, 6)) == Rational(-1, 2)*sqrt(3)
assert cos(pi*Rational(-5, 6)) == Rational(-1, 2)*sqrt(3)
assert cos(pi*Rational(1, 5)) == (sqrt(5) + 1)/4
assert cos(pi*Rational(2, 5)) == (sqrt(5) - 1)/4
assert cos(pi*Rational(3, 5)) == -cos(pi*Rational(2, 5))
assert cos(pi*Rational(4, 5)) == -cos(pi*Rational(1, 5))
assert cos(pi*Rational(6, 5)) == -cos(pi*Rational(1, 5))
assert cos(pi*Rational(8, 5)) == cos(pi*Rational(2, 5))
assert cos(pi*Rational(-1273, 5)) == -cos(pi*Rational(2, 5))
assert cos(pi/8) == sqrt((2 + sqrt(2))/4)
assert cos(pi/12) == sqrt(2)/4 + sqrt(6)/4
assert cos(pi*Rational(5, 12)) == -sqrt(2)/4 + sqrt(6)/4
assert cos(pi*Rational(7, 12)) == sqrt(2)/4 - sqrt(6)/4
assert cos(pi*Rational(11, 12)) == -sqrt(2)/4 - sqrt(6)/4
assert cos(pi*Rational(104, 105)) == -cos(pi/105)
assert cos(pi*Rational(106, 105)) == -cos(pi/105)
assert cos(pi*Rational(-104, 105)) == -cos(pi/105)
assert cos(pi*Rational(-106, 105)) == -cos(pi/105)
assert cos(x*I) == cosh(x)
assert cos(k*pi*I) == cosh(k*pi)
assert cos(r).is_real is True
assert cos(0, evaluate=False).is_algebraic
assert cos(a).is_algebraic is None
assert cos(na).is_algebraic is False
q = Symbol('q', rational=True)
assert cos(pi*q).is_algebraic
assert cos(pi*Rational(2, 7)).is_algebraic
assert cos(k*pi) == (-1)**k
assert cos(2*k*pi) == 1
for d in list(range(1, 22)) + [60, 85]:
for n in range(0, 2*d + 1):
x = n*pi/d
e = abs( float(cos(x)) - cos(float(x)) )
assert e < 1e-12
def test_issue_6190():
c = Float('123456789012345678901234567890.25', '')
for cls in [sin, cos, tan, cot]:
assert cls(c*pi) == cls(pi/4)
assert cls(4.125*pi) == cls(pi/8)
assert cls(4.7*pi) == cls((4.7 % 2)*pi)
def test_cos_series():
assert cos(x).series(x, 0, 9) == \
1 - x**2/2 + x**4/24 - x**6/720 + x**8/40320 + O(x**9)
def test_cos_rewrite():
assert cos(x).rewrite(exp) == exp(I*x)/2 + exp(-I*x)/2
assert cos(x).rewrite(tan) == (1 - tan(x/2)**2)/(1 + tan(x/2)**2)
assert cos(x).rewrite(cot) == -(1 - cot(x/2)**2)/(1 + cot(x/2)**2)
assert cos(sinh(x)).rewrite(
exp).subs(x, 3).n() == cos(x).rewrite(exp).subs(x, sinh(3)).n()
assert cos(cosh(x)).rewrite(
exp).subs(x, 3).n() == cos(x).rewrite(exp).subs(x, cosh(3)).n()
assert cos(tanh(x)).rewrite(
exp).subs(x, 3).n() == cos(x).rewrite(exp).subs(x, tanh(3)).n()
assert cos(coth(x)).rewrite(
exp).subs(x, 3).n() == cos(x).rewrite(exp).subs(x, coth(3)).n()
assert cos(sin(x)).rewrite(
exp).subs(x, 3).n() == cos(x).rewrite(exp).subs(x, sin(3)).n()
assert cos(cos(x)).rewrite(
exp).subs(x, 3).n() == cos(x).rewrite(exp).subs(x, cos(3)).n()
assert cos(tan(x)).rewrite(
exp).subs(x, 3).n() == cos(x).rewrite(exp).subs(x, tan(3)).n()
assert cos(cot(x)).rewrite(
exp).subs(x, 3).n() == cos(x).rewrite(exp).subs(x, cot(3)).n()
assert cos(log(x)).rewrite(Pow) == x**I/2 + x**-I/2
assert cos(x).rewrite(sec) == 1/sec(x)
assert cos(x).rewrite(sin) == sin(x + pi/2, evaluate=False)
assert cos(x).rewrite(csc) == 1/csc(-x + pi/2, evaluate=False)
assert cos(sin(x)).rewrite(Pow) == cos(sin(x))
def test_cos_expansion():
assert cos(x + y).expand(trig=True) == cos(x)*cos(y) - sin(x)*sin(y)
assert cos(x - y).expand(trig=True) == cos(x)*cos(y) + sin(x)*sin(y)
assert cos(y - x).expand(trig=True) == cos(x)*cos(y) + sin(x)*sin(y)
assert cos(2*x).expand(trig=True) == 2*cos(x)**2 - 1
assert cos(3*x).expand(trig=True) == 4*cos(x)**3 - 3*cos(x)
assert cos(4*x).expand(trig=True) == 8*cos(x)**4 - 8*cos(x)**2 + 1
_test_extrig(cos, 2, 2*cos(1)**2 - 1)
_test_extrig(cos, 3, 4*cos(1)**3 - 3*cos(1))
def test_cos_AccumBounds():
assert cos(AccumBounds(-oo, oo)) == AccumBounds(-1, 1)
assert cos(AccumBounds(0, oo)) == AccumBounds(-1, 1)
assert cos(AccumBounds(-oo, 0)) == AccumBounds(-1, 1)
assert cos(AccumBounds(0, 2*S.Pi)) == AccumBounds(-1, 1)
assert cos(AccumBounds(-S.Pi/3, S.Pi/4)) == AccumBounds(cos(-S.Pi/3), 1)
assert cos(AccumBounds(S.Pi*Rational(3, 4), S.Pi*Rational(5, 4))) == AccumBounds(-1, cos(S.Pi*Rational(3, 4)))
assert cos(AccumBounds(S.Pi*Rational(5, 4), S.Pi*Rational(4, 3))) == AccumBounds(cos(S.Pi*Rational(5, 4)), cos(S.Pi*Rational(4, 3)))
assert cos(AccumBounds(S.Pi/4, S.Pi/3)) == AccumBounds(cos(S.Pi/3), cos(S.Pi/4))
def test_cos_fdiff():
assert cos(x).fdiff() == -sin(x)
raises(ArgumentIndexError, lambda: cos(x).fdiff(2))
def test_tan():
assert tan(nan) is nan
assert tan(zoo) is nan
assert tan(oo) == AccumBounds(-oo, oo)
assert tan(oo) - tan(oo) == AccumBounds(-oo, oo)
assert tan.nargs == FiniteSet(1)
assert tan(oo*I) == I
assert tan(-oo*I) == -I
assert tan(0) == 0
assert tan(atan(x)) == x
assert tan(asin(x)) == x / sqrt(1 - x**2)
assert tan(acos(x)) == sqrt(1 - x**2) / x
assert tan(acot(x)) == 1 / x
assert tan(acsc(x)) == 1 / (sqrt(1 - 1 / x**2) * x)
assert tan(asec(x)) == sqrt(1 - 1 / x**2) * x
assert tan(atan2(y, x)) == y/x
assert tan(pi*I) == tanh(pi)*I
assert tan(-pi*I) == -tanh(pi)*I
assert tan(-2*I) == -tanh(2)*I
assert tan(pi) == 0
assert tan(-pi) == 0
assert tan(2*pi) == 0
assert tan(-2*pi) == 0
assert tan(-3*10**73*pi) == 0
assert tan(pi/2) is zoo
assert tan(pi*Rational(3, 2)) is zoo
assert tan(pi/3) == sqrt(3)
assert tan(pi*Rational(-2, 3)) == sqrt(3)
assert tan(pi/4) is S.One
assert tan(-pi/4) is S.NegativeOne
assert tan(pi*Rational(17, 4)) is S.One
assert tan(pi*Rational(-3, 4)) is S.One
assert tan(pi/5) == sqrt(5 - 2*sqrt(5))
assert tan(pi*Rational(2, 5)) == sqrt(5 + 2*sqrt(5))
assert tan(pi*Rational(18, 5)) == -sqrt(5 + 2*sqrt(5))
assert tan(pi*Rational(-16, 5)) == -sqrt(5 - 2*sqrt(5))
assert tan(pi/6) == 1/sqrt(3)
assert tan(-pi/6) == -1/sqrt(3)
assert tan(pi*Rational(7, 6)) == 1/sqrt(3)
assert tan(pi*Rational(-5, 6)) == 1/sqrt(3)
assert tan(pi/8) == -1 + sqrt(2)
assert tan(pi*Rational(3, 8)) == 1 + sqrt(2) # issue 15959
assert tan(pi*Rational(5, 8)) == -1 - sqrt(2)
assert tan(pi*Rational(7, 8)) == 1 - sqrt(2)
assert tan(pi/10) == sqrt(1 - 2*sqrt(5)/5)
assert tan(pi*Rational(3, 10)) == sqrt(1 + 2*sqrt(5)/5)
assert tan(pi*Rational(17, 10)) == -sqrt(1 + 2*sqrt(5)/5)
assert tan(pi*Rational(-31, 10)) == -sqrt(1 - 2*sqrt(5)/5)
assert tan(pi/12) == -sqrt(3) + 2
assert tan(pi*Rational(5, 12)) == sqrt(3) + 2
assert tan(pi*Rational(7, 12)) == -sqrt(3) - 2
assert tan(pi*Rational(11, 12)) == sqrt(3) - 2
assert tan(pi/24).radsimp() == -2 - sqrt(3) + sqrt(2) + sqrt(6)
assert tan(pi*Rational(5, 24)).radsimp() == -2 + sqrt(3) - sqrt(2) + sqrt(6)
assert tan(pi*Rational(7, 24)).radsimp() == 2 - sqrt(3) - sqrt(2) + sqrt(6)
assert tan(pi*Rational(11, 24)).radsimp() == 2 + sqrt(3) + sqrt(2) + sqrt(6)
assert tan(pi*Rational(13, 24)).radsimp() == -2 - sqrt(3) - sqrt(2) - sqrt(6)
assert tan(pi*Rational(17, 24)).radsimp() == -2 + sqrt(3) + sqrt(2) - sqrt(6)
assert tan(pi*Rational(19, 24)).radsimp() == 2 - sqrt(3) + sqrt(2) - sqrt(6)
assert tan(pi*Rational(23, 24)).radsimp() == 2 + sqrt(3) - sqrt(2) - sqrt(6)
assert tan(x*I) == tanh(x)*I
assert tan(k*pi) == 0
assert tan(17*k*pi) == 0
assert tan(k*pi*I) == tanh(k*pi)*I
assert tan(r).is_real is None
assert tan(r).is_extended_real is True
assert tan(0, evaluate=False).is_algebraic
assert tan(a).is_algebraic is None
assert tan(na).is_algebraic is False
assert tan(pi*Rational(10, 7)) == tan(pi*Rational(3, 7))
assert tan(pi*Rational(11, 7)) == -tan(pi*Rational(3, 7))
assert tan(pi*Rational(-11, 7)) == tan(pi*Rational(3, 7))
assert tan(pi*Rational(15, 14)) == tan(pi/14)
assert tan(pi*Rational(-15, 14)) == -tan(pi/14)
assert tan(r).is_finite is None
assert tan(I*r).is_finite is True
# https://github.com/sympy/sympy/issues/21177
f = tan(pi*(x + S(3)/2))/(3*x)
assert f.as_leading_term(x) == -1/(3*pi*x**2)
def test_tan_series():
assert tan(x).series(x, 0, 9) == \
x + x**3/3 + 2*x**5/15 + 17*x**7/315 + O(x**9)
def test_tan_rewrite():
neg_exp, pos_exp = exp(-x*I), exp(x*I)
assert tan(x).rewrite(exp) == I*(neg_exp - pos_exp)/(neg_exp + pos_exp)
assert tan(x).rewrite(sin) == 2*sin(x)**2/sin(2*x)
assert tan(x).rewrite(cos) == cos(x - S.Pi/2, evaluate=False)/cos(x)
assert tan(x).rewrite(cot) == 1/cot(x)
assert tan(sinh(x)).rewrite(
exp).subs(x, 3).n() == tan(x).rewrite(exp).subs(x, sinh(3)).n()
assert tan(cosh(x)).rewrite(
exp).subs(x, 3).n() == tan(x).rewrite(exp).subs(x, cosh(3)).n()
assert tan(tanh(x)).rewrite(
exp).subs(x, 3).n() == tan(x).rewrite(exp).subs(x, tanh(3)).n()
assert tan(coth(x)).rewrite(
exp).subs(x, 3).n() == tan(x).rewrite(exp).subs(x, coth(3)).n()
assert tan(sin(x)).rewrite(
exp).subs(x, 3).n() == tan(x).rewrite(exp).subs(x, sin(3)).n()
assert tan(cos(x)).rewrite(
exp).subs(x, 3).n() == tan(x).rewrite(exp).subs(x, cos(3)).n()
assert tan(tan(x)).rewrite(
exp).subs(x, 3).n() == tan(x).rewrite(exp).subs(x, tan(3)).n()
assert tan(cot(x)).rewrite(
exp).subs(x, 3).n() == tan(x).rewrite(exp).subs(x, cot(3)).n()
assert tan(log(x)).rewrite(Pow) == I*(x**-I - x**I)/(x**-I + x**I)
assert 0 == (cos(pi/34)*tan(pi/34) - sin(pi/34)).rewrite(pow)
assert 0 == (cos(pi/17)*tan(pi/17) - sin(pi/17)).rewrite(pow)
assert tan(pi/19).rewrite(pow) == tan(pi/19)
assert tan(pi*Rational(8, 19)).rewrite(sqrt) == tan(pi*Rational(8, 19))
assert tan(x).rewrite(sec) == sec(x)/sec(x - pi/2, evaluate=False)
assert tan(x).rewrite(csc) == csc(-x + pi/2, evaluate=False)/csc(x)
assert tan(sin(x)).rewrite(Pow) == tan(sin(x))
assert tan(pi*Rational(2, 5), evaluate=False).rewrite(sqrt) == sqrt(sqrt(5)/8 +
Rational(5, 8))/(Rational(-1, 4) + sqrt(5)/4)
def test_tan_subs():
assert tan(x).subs(tan(x), y) == y
assert tan(x).subs(x, y) == tan(y)
assert tan(x).subs(x, S.Pi/2) is zoo
assert tan(x).subs(x, S.Pi*Rational(3, 2)) is zoo
def test_tan_expansion():
assert tan(x + y).expand(trig=True) == ((tan(x) + tan(y))/(1 - tan(x)*tan(y))).expand()
assert tan(x - y).expand(trig=True) == ((tan(x) - tan(y))/(1 + tan(x)*tan(y))).expand()
assert tan(x + y + z).expand(trig=True) == (
(tan(x) + tan(y) + tan(z) - tan(x)*tan(y)*tan(z))/
(1 - tan(x)*tan(y) - tan(x)*tan(z) - tan(y)*tan(z))).expand()
assert 0 == tan(2*x).expand(trig=True).rewrite(tan).subs([(tan(x), Rational(1, 7))])*24 - 7
assert 0 == tan(3*x).expand(trig=True).rewrite(tan).subs([(tan(x), Rational(1, 5))])*55 - 37
assert 0 == tan(4*x - pi/4).expand(trig=True).rewrite(tan).subs([(tan(x), Rational(1, 5))])*239 - 1
_test_extrig(tan, 2, 2*tan(1)/(1 - tan(1)**2))
_test_extrig(tan, 3, (-tan(1)**3 + 3*tan(1))/(1 - 3*tan(1)**2))
def test_tan_AccumBounds():
assert tan(AccumBounds(-oo, oo)) == AccumBounds(-oo, oo)
assert tan(AccumBounds(S.Pi/3, S.Pi*Rational(2, 3))) == AccumBounds(-oo, oo)
assert tan(AccumBounds(S.Pi/6, S.Pi/3)) == AccumBounds(tan(S.Pi/6), tan(S.Pi/3))
def test_tan_fdiff():
assert tan(x).fdiff() == tan(x)**2 + 1
raises(ArgumentIndexError, lambda: tan(x).fdiff(2))
def test_cot():
assert cot(nan) is nan
assert cot.nargs == FiniteSet(1)
assert cot(oo*I) == -I
assert cot(-oo*I) == I
assert cot(zoo) is nan
assert cot(0) is zoo
assert cot(2*pi) is zoo
assert cot(acot(x)) == x
assert cot(atan(x)) == 1 / x
assert cot(asin(x)) == sqrt(1 - x**2) / x
assert cot(acos(x)) == x / sqrt(1 - x**2)
assert cot(acsc(x)) == sqrt(1 - 1 / x**2) * x
assert cot(asec(x)) == 1 / (sqrt(1 - 1 / x**2) * x)
assert cot(atan2(y, x)) == x/y
assert cot(pi*I) == -coth(pi)*I
assert cot(-pi*I) == coth(pi)*I
assert cot(-2*I) == coth(2)*I
assert cot(pi) == cot(2*pi) == cot(3*pi)
assert cot(-pi) == cot(-2*pi) == cot(-3*pi)
assert cot(pi/2) == 0
assert cot(-pi/2) == 0
assert cot(pi*Rational(5, 2)) == 0
assert cot(pi*Rational(7, 2)) == 0
assert cot(pi/3) == 1/sqrt(3)
assert cot(pi*Rational(-2, 3)) == 1/sqrt(3)
assert cot(pi/4) is S.One
assert cot(-pi/4) is S.NegativeOne
assert cot(pi*Rational(17, 4)) is S.One
assert cot(pi*Rational(-3, 4)) is S.One
assert cot(pi/6) == sqrt(3)
assert cot(-pi/6) == -sqrt(3)
assert cot(pi*Rational(7, 6)) == sqrt(3)
assert cot(pi*Rational(-5, 6)) == sqrt(3)
assert cot(pi/8) == 1 + sqrt(2)
assert cot(pi*Rational(3, 8)) == -1 + sqrt(2)
assert cot(pi*Rational(5, 8)) == 1 - sqrt(2)
assert cot(pi*Rational(7, 8)) == -1 - sqrt(2)
assert cot(pi/12) == sqrt(3) + 2
assert cot(pi*Rational(5, 12)) == -sqrt(3) + 2
assert cot(pi*Rational(7, 12)) == sqrt(3) - 2
assert cot(pi*Rational(11, 12)) == -sqrt(3) - 2
assert cot(pi/24).radsimp() == sqrt(2) + sqrt(3) + 2 + sqrt(6)
assert cot(pi*Rational(5, 24)).radsimp() == -sqrt(2) - sqrt(3) + 2 + sqrt(6)
assert cot(pi*Rational(7, 24)).radsimp() == -sqrt(2) + sqrt(3) - 2 + sqrt(6)
assert cot(pi*Rational(11, 24)).radsimp() == sqrt(2) - sqrt(3) - 2 + sqrt(6)
assert cot(pi*Rational(13, 24)).radsimp() == -sqrt(2) + sqrt(3) + 2 - sqrt(6)
assert cot(pi*Rational(17, 24)).radsimp() == sqrt(2) - sqrt(3) + 2 - sqrt(6)
assert cot(pi*Rational(19, 24)).radsimp() == sqrt(2) + sqrt(3) - 2 - sqrt(6)
assert cot(pi*Rational(23, 24)).radsimp() == -sqrt(2) - sqrt(3) - 2 - sqrt(6)
assert cot(x*I) == -coth(x)*I
assert cot(k*pi*I) == -coth(k*pi)*I
assert cot(r).is_real is None
assert cot(r).is_extended_real is True
assert cot(a).is_algebraic is None
assert cot(na).is_algebraic is False
assert cot(pi*Rational(10, 7)) == cot(pi*Rational(3, 7))
assert cot(pi*Rational(11, 7)) == -cot(pi*Rational(3, 7))
assert cot(pi*Rational(-11, 7)) == cot(pi*Rational(3, 7))
assert cot(pi*Rational(39, 34)) == cot(pi*Rational(5, 34))
assert cot(pi*Rational(-41, 34)) == -cot(pi*Rational(7, 34))
assert cot(x).is_finite is None
assert cot(r).is_finite is None
i = Symbol('i', imaginary=True)
assert cot(i).is_finite is True
assert cot(x).subs(x, 3*pi) is zoo
# https://github.com/sympy/sympy/issues/21177
f = cot(pi*(x + 4))/(3*x)
assert f.as_leading_term(x) == 1/(3*pi*x**2)
def test_tan_cot_sin_cos_evalf():
assert abs((tan(pi*Rational(8, 15))*cos(pi*Rational(8, 15))/sin(pi*Rational(8, 15)) - 1).evalf()) < 1e-14
assert abs((cot(pi*Rational(4, 15))*sin(pi*Rational(4, 15))/cos(pi*Rational(4, 15)) - 1).evalf()) < 1e-14
@XFAIL
def test_tan_cot_sin_cos_ratsimp():
assert 1 == (tan(pi*Rational(8, 15))*cos(pi*Rational(8, 15))/sin(pi*Rational(8, 15))).ratsimp()
assert 1 == (cot(pi*Rational(4, 15))*sin(pi*Rational(4, 15))/cos(pi*Rational(4, 15))).ratsimp()
def test_cot_series():
assert cot(x).series(x, 0, 9) == \
1/x - x/3 - x**3/45 - 2*x**5/945 - x**7/4725 + O(x**9)
# issue 6210
assert cot(x**4 + x**5).series(x, 0, 1) == \
x**(-4) - 1/x**3 + x**(-2) - 1/x + 1 + O(x)
assert cot(pi*(1-x)).series(x, 0, 3) == -1/(pi*x) + pi*x/3 + O(x**3)
assert cot(x).taylor_term(0, x) == 1/x
assert cot(x).taylor_term(2, x) is S.Zero
assert cot(x).taylor_term(3, x) == -x**3/45
def test_cot_rewrite():
neg_exp, pos_exp = exp(-x*I), exp(x*I)
assert cot(x).rewrite(exp) == I*(pos_exp + neg_exp)/(pos_exp - neg_exp)
assert cot(x).rewrite(sin) == sin(2*x)/(2*(sin(x)**2))
assert cot(x).rewrite(cos) == cos(x)/cos(x - pi/2, evaluate=False)
assert cot(x).rewrite(tan) == 1/tan(x)
assert cot(sinh(x)).rewrite(
exp).subs(x, 3).n() == cot(x).rewrite(exp).subs(x, sinh(3)).n()
assert cot(cosh(x)).rewrite(
exp).subs(x, 3).n() == cot(x).rewrite(exp).subs(x, cosh(3)).n()
assert cot(tanh(x)).rewrite(
exp).subs(x, 3).n() == cot(x).rewrite(exp).subs(x, tanh(3)).n()
assert cot(coth(x)).rewrite(
exp).subs(x, 3).n() == cot(x).rewrite(exp).subs(x, coth(3)).n()
assert cot(sin(x)).rewrite(
exp).subs(x, 3).n() == cot(x).rewrite(exp).subs(x, sin(3)).n()
assert cot(tan(x)).rewrite(
exp).subs(x, 3).n() == cot(x).rewrite(exp).subs(x, tan(3)).n()
assert cot(log(x)).rewrite(Pow) == -I*(x**-I + x**I)/(x**-I - x**I)
assert cot(pi*Rational(4, 34)).rewrite(pow).ratsimp() == (cos(pi*Rational(4, 34))/sin(pi*Rational(4, 34))).rewrite(pow).ratsimp()
assert cot(pi*Rational(4, 17)).rewrite(pow) == (cos(pi*Rational(4, 17))/sin(pi*Rational(4, 17))).rewrite(pow)
assert cot(pi/19).rewrite(pow) == cot(pi/19)
assert cot(pi/19).rewrite(sqrt) == cot(pi/19)
assert cot(x).rewrite(sec) == sec(x - pi / 2, evaluate=False) / sec(x)
assert cot(x).rewrite(csc) == csc(x) / csc(- x + pi / 2, evaluate=False)
assert cot(sin(x)).rewrite(Pow) == cot(sin(x))
assert cot(pi*Rational(2, 5), evaluate=False).rewrite(sqrt) == (Rational(-1, 4) + sqrt(5)/4)/\
sqrt(sqrt(5)/8 + Rational(5, 8))
def test_cot_subs():
assert cot(x).subs(cot(x), y) == y
assert cot(x).subs(x, y) == cot(y)
assert cot(x).subs(x, 0) is zoo
assert cot(x).subs(x, S.Pi) is zoo
def test_cot_expansion():
assert cot(x + y).expand(trig=True).together() == (
(cot(x)*cot(y) - 1)/(cot(x) + cot(y)))
assert cot(x - y).expand(trig=True).together() == (
cot(x)*cot(-y) - 1)/(cot(x) + cot(-y))
assert cot(x + y + z).expand(trig=True).together() == (
(cot(x)*cot(y)*cot(z) - cot(x) - cot(y) - cot(z))/
(-1 + cot(x)*cot(y) + cot(x)*cot(z) + cot(y)*cot(z)))
assert cot(3*x).expand(trig=True).together() == (
(cot(x)**2 - 3)*cot(x)/(3*cot(x)**2 - 1))
assert cot(2*x).expand(trig=True) == cot(x)/2 - 1/(2*cot(x))
assert cot(3*x).expand(trig=True).together() == (
cot(x)**2 - 3)*cot(x)/(3*cot(x)**2 - 1)
assert cot(4*x - pi/4).expand(trig=True).cancel() == (
-tan(x)**4 + 4*tan(x)**3 + 6*tan(x)**2 - 4*tan(x) - 1
)/(tan(x)**4 + 4*tan(x)**3 - 6*tan(x)**2 - 4*tan(x) + 1)
_test_extrig(cot, 2, (-1 + cot(1)**2)/(2*cot(1)))
_test_extrig(cot, 3, (-3*cot(1) + cot(1)**3)/(-1 + 3*cot(1)**2))
def test_cot_AccumBounds():
assert cot(AccumBounds(-oo, oo)) == AccumBounds(-oo, oo)
assert cot(AccumBounds(-S.Pi/3, S.Pi/3)) == AccumBounds(-oo, oo)
assert cot(AccumBounds(S.Pi/6, S.Pi/3)) == AccumBounds(cot(S.Pi/3), cot(S.Pi/6))
def test_cot_fdiff():
assert cot(x).fdiff() == -cot(x)**2 - 1
raises(ArgumentIndexError, lambda: cot(x).fdiff(2))
def test_sinc():
assert isinstance(sinc(x), sinc)
s = Symbol('s', zero=True)
assert sinc(s) is S.One
assert sinc(S.Infinity) is S.Zero
assert sinc(S.NegativeInfinity) is S.Zero
assert sinc(S.NaN) is S.NaN
assert sinc(S.ComplexInfinity) is S.NaN
n = Symbol('n', integer=True, nonzero=True)
assert sinc(n*pi) is S.Zero
assert sinc(-n*pi) is S.Zero
assert sinc(pi/2) == 2 / pi
assert sinc(-pi/2) == 2 / pi
assert sinc(pi*Rational(5, 2)) == 2 / (5*pi)
assert sinc(pi*Rational(7, 2)) == -2 / (7*pi)
assert sinc(-x) == sinc(x)
assert sinc(x).diff(x) == cos(x)/x - sin(x)/x**2
assert sinc(x).diff(x) == (sin(x)/x).diff(x)
assert sinc(x).diff(x, x) == (-sin(x) - 2*cos(x)/x + 2*sin(x)/x**2)/x
assert sinc(x).diff(x, x) == (sin(x)/x).diff(x, x)
assert limit(sinc(x).diff(x), x, 0) == 0
assert limit(sinc(x).diff(x, x), x, 0) == -S(1)/3
# https://github.com/sympy/sympy/issues/11402
#
# assert sinc(x).diff(x) == Piecewise(((x*cos(x) - sin(x)) / x**2, Ne(x, 0)), (0, True))
#
# assert sinc(x).diff(x).equals(sinc(x).rewrite(sin).diff(x))
#
# assert sinc(x).diff(x).subs(x, 0) is S.Zero
assert sinc(x).series() == 1 - x**2/6 + x**4/120 + O(x**6)
assert sinc(x).rewrite(jn) == jn(0, x)
assert sinc(x).rewrite(sin) == Piecewise((sin(x)/x, Ne(x, 0)), (1, True))
def test_asin():
assert asin(nan) is nan
assert asin.nargs == FiniteSet(1)
assert asin(oo) == -I*oo
assert asin(-oo) == I*oo
assert asin(zoo) is zoo
# Note: asin(-x) = - asin(x)
assert asin(0) == 0
assert asin(1) == pi/2
assert asin(-1) == -pi/2
assert asin(sqrt(3)/2) == pi/3
assert asin(-sqrt(3)/2) == -pi/3
assert asin(sqrt(2)/2) == pi/4
assert asin(-sqrt(2)/2) == -pi/4
assert asin(sqrt((5 - sqrt(5))/8)) == pi/5
assert asin(-sqrt((5 - sqrt(5))/8)) == -pi/5
assert asin(S.Half) == pi/6
assert asin(Rational(-1, 2)) == -pi/6
assert asin((sqrt(2 - sqrt(2)))/2) == pi/8
assert asin(-(sqrt(2 - sqrt(2)))/2) == -pi/8
assert asin((sqrt(5) - 1)/4) == pi/10
assert asin(-(sqrt(5) - 1)/4) == -pi/10
assert asin((sqrt(3) - 1)/sqrt(2**3)) == pi/12
assert asin(-(sqrt(3) - 1)/sqrt(2**3)) == -pi/12
# check round-trip for exact values:
for d in [5, 6, 8, 10, 12]:
for n in range(-(d//2), d//2 + 1):
if gcd(n, d) == 1:
assert asin(sin(n*pi/d)) == n*pi/d
assert asin(x).diff(x) == 1/sqrt(1 - x**2)
assert asin(1/x).as_leading_term(x) == I*log(1/x)
assert asin(0.2).is_real is True
assert asin(-2).is_real is False
assert asin(r).is_real is None
assert asin(-2*I) == -I*asinh(2)
assert asin(Rational(1, 7), evaluate=False).is_positive is True
assert asin(Rational(-1, 7), evaluate=False).is_positive is False
assert asin(p).is_positive is None
assert asin(sin(Rational(7, 2))) == Rational(-7, 2) + pi
assert asin(sin(Rational(-7, 4))) == Rational(7, 4) - pi
assert unchanged(asin, cos(x))
def test_asin_series():
assert asin(x).series(x, 0, 9) == \
x + x**3/6 + 3*x**5/40 + 5*x**7/112 + O(x**9)
t5 = asin(x).taylor_term(5, x)
assert t5 == 3*x**5/40
assert asin(x).taylor_term(7, x, t5, 0) == 5*x**7/112
def test_asin_rewrite():
assert asin(x).rewrite(log) == -I*log(I*x + sqrt(1 - x**2))
assert asin(x).rewrite(atan) == 2*atan(x/(1 + sqrt(1 - x**2)))
assert asin(x).rewrite(acos) == S.Pi/2 - acos(x)
assert asin(x).rewrite(acot) == 2*acot((sqrt(-x**2 + 1) + 1)/x)
assert asin(x).rewrite(asec) == -asec(1/x) + pi/2
assert asin(x).rewrite(acsc) == acsc(1/x)
def test_asin_fdiff():
assert asin(x).fdiff() == 1/sqrt(1 - x**2)
raises(ArgumentIndexError, lambda: asin(x).fdiff(2))
def test_acos():
assert acos(nan) is nan
assert acos(zoo) is zoo
assert acos.nargs == FiniteSet(1)
assert acos(oo) == I*oo
assert acos(-oo) == -I*oo
# Note: acos(-x) = pi - acos(x)
assert acos(0) == pi/2
assert acos(S.Half) == pi/3
assert acos(Rational(-1, 2)) == pi*Rational(2, 3)
assert acos(1) == 0
assert acos(-1) == pi
assert acos(sqrt(2)/2) == pi/4
assert acos(-sqrt(2)/2) == pi*Rational(3, 4)
# check round-trip for exact values:
for d in [5, 6, 8, 10, 12]:
for num in range(d):
if gcd(num, d) == 1:
assert acos(cos(num*pi/d)) == num*pi/d
assert acos(2*I) == pi/2 - asin(2*I)
assert acos(x).diff(x) == -1/sqrt(1 - x**2)
assert acos(1/x).as_leading_term(x) == I*log(1/x)
assert acos(0.2).is_real is True
assert acos(-2).is_real is False
assert acos(r).is_real is None
assert acos(Rational(1, 7), evaluate=False).is_positive is True
assert acos(Rational(-1, 7), evaluate=False).is_positive is True
assert acos(Rational(3, 2), evaluate=False).is_positive is False
assert acos(p).is_positive is None
assert acos(2 + p).conjugate() != acos(10 + p)
assert acos(-3 + n).conjugate() != acos(-3 + n)
assert acos(Rational(1, 3)).conjugate() == acos(Rational(1, 3))
assert acos(Rational(-1, 3)).conjugate() == acos(Rational(-1, 3))
assert acos(p + n*I).conjugate() == acos(p - n*I)
assert acos(z).conjugate() != acos(conjugate(z))
def test_acos_series():
assert acos(x).series(x, 0, 8) == \
pi/2 - x - x**3/6 - 3*x**5/40 - 5*x**7/112 + O(x**8)
assert acos(x).series(x, 0, 8) == pi/2 - asin(x).series(x, 0, 8)
t5 = acos(x).taylor_term(5, x)
assert t5 == -3*x**5/40
assert acos(x).taylor_term(7, x, t5, 0) == -5*x**7/112
assert acos(x).taylor_term(0, x) == pi/2
assert acos(x).taylor_term(2, x) is S.Zero
def test_acos_rewrite():
assert acos(x).rewrite(log) == pi/2 + I*log(I*x + sqrt(1 - x**2))
assert acos(x).rewrite(atan) == \
atan(sqrt(1 - x**2)/x) + (pi/2)*(1 - x*sqrt(1/x**2))
assert acos(0).rewrite(atan) == S.Pi/2
assert acos(0.5).rewrite(atan) == acos(0.5).rewrite(log)
assert acos(x).rewrite(asin) == S.Pi/2 - asin(x)
assert acos(x).rewrite(acot) == -2*acot((sqrt(-x**2 + 1) + 1)/x) + pi/2
assert acos(x).rewrite(asec) == asec(1/x)
assert acos(x).rewrite(acsc) == -acsc(1/x) + pi/2
def test_acos_fdiff():
assert acos(x).fdiff() == -1/sqrt(1 - x**2)
raises(ArgumentIndexError, lambda: acos(x).fdiff(2))
def test_atan():
assert atan(nan) is nan
assert atan.nargs == FiniteSet(1)
assert atan(oo) == pi/2
assert atan(-oo) == -pi/2
assert atan(zoo) == AccumBounds(-pi/2, pi/2)
assert atan(0) == 0
assert atan(1) == pi/4
assert atan(sqrt(3)) == pi/3
assert atan(-(1 + sqrt(2))) == pi*Rational(-3, 8)
assert atan(sqrt(5 - 2 * sqrt(5))) == pi/5
assert atan(-sqrt(1 - 2 * sqrt(5)/ 5)) == -pi/10
assert atan(sqrt(1 + 2 * sqrt(5) / 5)) == pi*Rational(3, 10)
assert atan(-2 + sqrt(3)) == -pi/12
assert atan(2 + sqrt(3)) == pi*Rational(5, 12)
assert atan(-2 - sqrt(3)) == pi*Rational(-5, 12)
# check round-trip for exact values:
for d in [5, 6, 8, 10, 12]:
for num in range(-(d//2), d//2 + 1):
if gcd(num, d) == 1:
assert atan(tan(num*pi/d)) == num*pi/d
assert atan(oo) == pi/2
assert atan(x).diff(x) == 1/(1 + x**2)
assert atan(1/x).as_leading_term(x) == pi/2
assert atan(r).is_real is True
assert atan(-2*I) == -I*atanh(2)
assert unchanged(atan, cot(x))
assert atan(cot(Rational(1, 4))) == Rational(-1, 4) + pi/2
assert acot(Rational(1, 4)).is_rational is False
for s in (x, p, n, np, nn, nz, ep, en, enp, enn, enz):
if s.is_real or s.is_extended_real is None:
assert s.is_nonzero is atan(s).is_nonzero
assert s.is_positive is atan(s).is_positive
assert s.is_negative is atan(s).is_negative
assert s.is_nonpositive is atan(s).is_nonpositive
assert s.is_nonnegative is atan(s).is_nonnegative
else:
assert s.is_extended_nonzero is atan(s).is_nonzero
assert s.is_extended_positive is atan(s).is_positive
assert s.is_extended_negative is atan(s).is_negative
assert s.is_extended_nonpositive is atan(s).is_nonpositive
assert s.is_extended_nonnegative is atan(s).is_nonnegative
assert s.is_extended_nonzero is atan(s).is_extended_nonzero
assert s.is_extended_positive is atan(s).is_extended_positive
assert s.is_extended_negative is atan(s).is_extended_negative
assert s.is_extended_nonpositive is atan(s).is_extended_nonpositive
assert s.is_extended_nonnegative is atan(s).is_extended_nonnegative
def test_atan_rewrite():
assert atan(x).rewrite(log) == I*(log(1 - I*x)-log(1 + I*x))/2
assert atan(x).rewrite(asin) == (-asin(1/sqrt(x**2 + 1)) + pi/2)*sqrt(x**2)/x
assert atan(x).rewrite(acos) == sqrt(x**2)*acos(1/sqrt(x**2 + 1))/x
assert atan(x).rewrite(acot) == acot(1/x)
assert atan(x).rewrite(asec) == sqrt(x**2)*asec(sqrt(x**2 + 1))/x
assert atan(x).rewrite(acsc) == (-acsc(sqrt(x**2 + 1)) + pi/2)*sqrt(x**2)/x
assert atan(-5*I).evalf() == atan(x).rewrite(log).evalf(subs={x:-5*I})
assert atan(5*I).evalf() == atan(x).rewrite(log).evalf(subs={x:5*I})
def test_atan_fdiff():
assert atan(x).fdiff() == 1/(x**2 + 1)
raises(ArgumentIndexError, lambda: atan(x).fdiff(2))
def test_atan2():
assert atan2.nargs == FiniteSet(2)
assert atan2(0, 0) is S.NaN
assert atan2(0, 1) == 0
assert atan2(1, 1) == pi/4
assert atan2(1, 0) == pi/2
assert atan2(1, -1) == pi*Rational(3, 4)
assert atan2(0, -1) == pi
assert atan2(-1, -1) == pi*Rational(-3, 4)
assert atan2(-1, 0) == -pi/2
assert atan2(-1, 1) == -pi/4
i = symbols('i', imaginary=True)
r = symbols('r', real=True)
eq = atan2(r, i)
ans = -I*log((i + I*r)/sqrt(i**2 + r**2))
reps = ((r, 2), (i, I))
assert eq.subs(reps) == ans.subs(reps)
x = Symbol('x', negative=True)
y = Symbol('y', negative=True)
assert atan2(y, x) == atan(y/x) - pi
y = Symbol('y', nonnegative=True)
assert atan2(y, x) == atan(y/x) + pi
y = Symbol('y')
assert atan2(y, x) == atan2(y, x, evaluate=False)
u = Symbol("u", positive=True)
assert atan2(0, u) == 0
u = Symbol("u", negative=True)
assert atan2(0, u) == pi
assert atan2(y, oo) == 0
assert atan2(y, -oo)== 2*pi*Heaviside(re(y), S.Half) - pi
assert atan2(y, x).rewrite(log) == -I*log((x + I*y)/sqrt(x**2 + y**2))
assert atan2(0, 0) is S.NaN
ex = atan2(y, x) - arg(x + I*y)
assert ex.subs({x:2, y:3}).rewrite(arg) == 0
assert ex.subs({x:2, y:3*I}).rewrite(arg) == -pi - I*log(sqrt(5)*I/5)
assert ex.subs({x:2*I, y:3}).rewrite(arg) == -pi/2 - I*log(sqrt(5)*I)
assert ex.subs({x:2*I, y:3*I}).rewrite(arg) == -pi + atan(Rational(2, 3)) + atan(Rational(3, 2))
i = symbols('i', imaginary=True)
r = symbols('r', real=True)
e = atan2(i, r)
rewrite = e.rewrite(arg)
reps = {i: I, r: -2}
assert rewrite == -I*log(abs(I*i + r)/sqrt(abs(i**2 + r**2))) + arg((I*i + r)/sqrt(i**2 + r**2))
assert (e - rewrite).subs(reps).equals(0)
assert atan2(0, x).rewrite(atan) == Piecewise((pi, re(x) < 0),
(0, Ne(x, 0)),
(nan, True))
assert atan2(0, r).rewrite(atan) == Piecewise((pi, r < 0), (0, Ne(r, 0)), (S.NaN, True))
assert atan2(0, i),rewrite(atan) == 0
assert atan2(0, r + i).rewrite(atan) == Piecewise((pi, r < 0), (0, True))
assert atan2(y, x).rewrite(atan) == Piecewise(
(2*atan(y/(x + sqrt(x**2 + y**2))), Ne(y, 0)),
(pi, re(x) < 0),
(0, (re(x) > 0) | Ne(im(x), 0)),
(nan, True))
assert conjugate(atan2(x, y)) == atan2(conjugate(x), conjugate(y))
assert diff(atan2(y, x), x) == -y/(x**2 + y**2)
assert diff(atan2(y, x), y) == x/(x**2 + y**2)
assert simplify(diff(atan2(y, x).rewrite(log), x)) == -y/(x**2 + y**2)
assert simplify(diff(atan2(y, x).rewrite(log), y)) == x/(x**2 + y**2)
assert str(atan2(1, 2).evalf(5)) == '0.46365'
raises(ArgumentIndexError, lambda: atan2(x, y).fdiff(3))
def test_issue_17461():
class A(Symbol):
is_extended_real = True
def _eval_evalf(self, prec):
return Float(5.0)
x = A('X')
y = A('Y')
assert abs(atan2(x, y).evalf() - 0.785398163397448) <= 1e-10
def test_acot():
assert acot(nan) is nan
assert acot.nargs == FiniteSet(1)
assert acot(-oo) == 0
assert acot(oo) == 0
assert acot(zoo) == 0
assert acot(1) == pi/4
assert acot(0) == pi/2
assert acot(sqrt(3)/3) == pi/3
assert acot(1/sqrt(3)) == pi/3
assert acot(-1/sqrt(3)) == -pi/3
assert acot(x).diff(x) == -1/(1 + x**2)
assert acot(1/x).as_leading_term(x) == x
assert acot(r).is_extended_real is True
assert acot(I*pi) == -I*acoth(pi)
assert acot(-2*I) == I*acoth(2)
assert acot(x).is_positive is None
assert acot(n).is_positive is False
assert acot(p).is_positive is True
assert acot(I).is_positive is False
assert acot(Rational(1, 4)).is_rational is False
assert unchanged(acot, cot(x))
assert unchanged(acot, tan(x))
assert acot(cot(Rational(1, 4))) == Rational(1, 4)
assert acot(tan(Rational(-1, 4))) == Rational(1, 4) - pi/2
def test_acot_rewrite():
assert acot(x).rewrite(log) == I*(log(1 - I/x)-log(1 + I/x))/2
assert acot(x).rewrite(asin) == x*(-asin(sqrt(-x**2)/sqrt(-x**2 - 1)) + pi/2)*sqrt(x**(-2))
assert acot(x).rewrite(acos) == x*sqrt(x**(-2))*acos(sqrt(-x**2)/sqrt(-x**2 - 1))
assert acot(x).rewrite(atan) == atan(1/x)
assert acot(x).rewrite(asec) == x*sqrt(x**(-2))*asec(sqrt((x**2 + 1)/x**2))
assert acot(x).rewrite(acsc) == x*(-acsc(sqrt((x**2 + 1)/x**2)) + pi/2)*sqrt(x**(-2))
assert acot(-I/5).evalf() == acot(x).rewrite(log).evalf(subs={x:-I/5})
assert acot(I/5).evalf() == acot(x).rewrite(log).evalf(subs={x:I/5})
def test_acot_fdiff():
assert acot(x).fdiff() == -1/(x**2 + 1)
raises(ArgumentIndexError, lambda: acot(x).fdiff(2))
def test_attributes():
assert sin(x).args == (x,)
def test_sincos_rewrite():
assert sin(pi/2 - x) == cos(x)
assert sin(pi - x) == sin(x)
assert cos(pi/2 - x) == sin(x)
assert cos(pi - x) == -cos(x)
def _check_even_rewrite(func, arg):
"""Checks that the expr has been rewritten using f(-x) -> f(x)
arg : -x
"""
return func(arg).args[0] == -arg
def _check_odd_rewrite(func, arg):
"""Checks that the expr has been rewritten using f(-x) -> -f(x)
arg : -x
"""
return func(arg).func.is_Mul
def _check_no_rewrite(func, arg):
"""Checks that the expr is not rewritten"""
return func(arg).args[0] == arg
def test_evenodd_rewrite():
a = cos(2) # negative
b = sin(1) # positive
even = [cos]
odd = [sin, tan, cot, asin, atan, acot]
with_minus = [-1, -2**1024 * E, -pi/105, -x*y, -x - y]
for func in even:
for expr in with_minus:
assert _check_even_rewrite(func, expr)
assert _check_no_rewrite(func, a*b)
assert func(
x - y) == func(y - x) # it doesn't matter which form is canonical
for func in odd:
for expr in with_minus:
assert _check_odd_rewrite(func, expr)
assert _check_no_rewrite(func, a*b)
assert func(
x - y) == -func(y - x) # it doesn't matter which form is canonical
def test_issue_4547():
assert sin(x).rewrite(cot) == 2*cot(x/2)/(1 + cot(x/2)**2)
assert cos(x).rewrite(cot) == -(1 - cot(x/2)**2)/(1 + cot(x/2)**2)
assert tan(x).rewrite(cot) == 1/cot(x)
assert cot(x).fdiff() == -1 - cot(x)**2
def test_as_leading_term_issue_5272():
assert sin(x).as_leading_term(x) == x
assert cos(x).as_leading_term(x) == 1
assert tan(x).as_leading_term(x) == x
assert cot(x).as_leading_term(x) == 1/x
assert asin(x).as_leading_term(x) == x
assert acos(x).as_leading_term(x) == pi/2
assert atan(x).as_leading_term(x) == x
assert acot(x).as_leading_term(x) == pi/2
def test_leading_terms():
assert sin(1/x).as_leading_term(x) == AccumBounds(-1 , 1)
assert sin(S.Half).as_leading_term(x) == sin(S.Half)
assert cos(1/x).as_leading_term(x) == AccumBounds(-1 , 1)
assert cos(S.Half).as_leading_term(x) == cos(S.Half)
for func in [tan, cot]:
for a in (1/x, S.Half):
eq = func(a)
assert eq.as_leading_term(x) == eq
# https://github.com/sympy/sympy/issues/21038
f = sin(pi*(x + 4))/(3*x)
assert f.as_leading_term(x) == pi/3
def test_atan2_expansion():
assert cancel(atan2(x**2, x + 1).diff(x) - atan(x**2/(x + 1)).diff(x)) == 0
assert cancel(atan(y/x).series(y, 0, 5) - atan2(y, x).series(y, 0, 5)
+ atan2(0, x) - atan(0)) == O(y**5)
assert cancel(atan(y/x).series(x, 1, 4) - atan2(y, x).series(x, 1, 4)
+ atan2(y, 1) - atan(y)) == O((x - 1)**4, (x, 1))
assert cancel(atan((y + x)/x).series(x, 1, 3) - atan2(y + x, x).series(x, 1, 3)
+ atan2(1 + y, 1) - atan(1 + y)) == O((x - 1)**3, (x, 1))
assert Matrix([atan2(y, x)]).jacobian([y, x]) == \
Matrix([[x/(y**2 + x**2), -y/(y**2 + x**2)]])
def test_aseries():
def t(n, v, d, e):
assert abs(
n(1/v).evalf() - n(1/x).series(x, dir=d).removeO().subs(x, v)) < e
t(atan, 0.1, '+', 1e-5)
t(atan, -0.1, '-', 1e-5)
t(acot, 0.1, '+', 1e-5)
t(acot, -0.1, '-', 1e-5)
def test_issue_4420():
i = Symbol('i', integer=True)
e = Symbol('e', even=True)
o = Symbol('o', odd=True)
# unknown parity for variable
assert cos(4*i*pi) == 1
assert sin(4*i*pi) == 0
assert tan(4*i*pi) == 0
assert cot(4*i*pi) is zoo
assert cos(3*i*pi) == cos(pi*i) # +/-1
assert sin(3*i*pi) == 0
assert tan(3*i*pi) == 0
assert cot(3*i*pi) is zoo
assert cos(4.0*i*pi) == 1
assert sin(4.0*i*pi) == 0
assert tan(4.0*i*pi) == 0
assert cot(4.0*i*pi) is zoo
assert cos(3.0*i*pi) == cos(pi*i) # +/-1
assert sin(3.0*i*pi) == 0
assert tan(3.0*i*pi) == 0
assert cot(3.0*i*pi) is zoo
assert cos(4.5*i*pi) == cos(0.5*pi*i)
assert sin(4.5*i*pi) == sin(0.5*pi*i)
assert tan(4.5*i*pi) == tan(0.5*pi*i)
assert cot(4.5*i*pi) == cot(0.5*pi*i)
# parity of variable is known
assert cos(4*e*pi) == 1
assert sin(4*e*pi) == 0
assert tan(4*e*pi) == 0
assert cot(4*e*pi) is zoo
assert cos(3*e*pi) == 1
assert sin(3*e*pi) == 0
assert tan(3*e*pi) == 0
assert cot(3*e*pi) is zoo
assert cos(4.0*e*pi) == 1
assert sin(4.0*e*pi) == 0
assert tan(4.0*e*pi) == 0
assert cot(4.0*e*pi) is zoo
assert cos(3.0*e*pi) == 1
assert sin(3.0*e*pi) == 0
assert tan(3.0*e*pi) == 0
assert cot(3.0*e*pi) is zoo
assert cos(4.5*e*pi) == cos(0.5*pi*e)
assert sin(4.5*e*pi) == sin(0.5*pi*e)
assert tan(4.5*e*pi) == tan(0.5*pi*e)
assert cot(4.5*e*pi) == cot(0.5*pi*e)
assert cos(4*o*pi) == 1
assert sin(4*o*pi) == 0
assert tan(4*o*pi) == 0
assert cot(4*o*pi) is zoo
assert cos(3*o*pi) == -1
assert sin(3*o*pi) == 0
assert tan(3*o*pi) == 0
assert cot(3*o*pi) is zoo
assert cos(4.0*o*pi) == 1
assert sin(4.0*o*pi) == 0
assert tan(4.0*o*pi) == 0
assert cot(4.0*o*pi) is zoo
assert cos(3.0*o*pi) == -1
assert sin(3.0*o*pi) == 0
assert tan(3.0*o*pi) == 0
assert cot(3.0*o*pi) is zoo
assert cos(4.5*o*pi) == cos(0.5*pi*o)
assert sin(4.5*o*pi) == sin(0.5*pi*o)
assert tan(4.5*o*pi) == tan(0.5*pi*o)
assert cot(4.5*o*pi) == cot(0.5*pi*o)
# x could be imaginary
assert cos(4*x*pi) == cos(4*pi*x)
assert sin(4*x*pi) == sin(4*pi*x)
assert tan(4*x*pi) == tan(4*pi*x)
assert cot(4*x*pi) == cot(4*pi*x)
assert cos(3*x*pi) == cos(3*pi*x)
assert sin(3*x*pi) == sin(3*pi*x)
assert tan(3*x*pi) == tan(3*pi*x)
assert cot(3*x*pi) == cot(3*pi*x)
assert cos(4.0*x*pi) == cos(4.0*pi*x)
assert sin(4.0*x*pi) == sin(4.0*pi*x)
assert tan(4.0*x*pi) == tan(4.0*pi*x)
assert cot(4.0*x*pi) == cot(4.0*pi*x)
assert cos(3.0*x*pi) == cos(3.0*pi*x)
assert sin(3.0*x*pi) == sin(3.0*pi*x)
assert tan(3.0*x*pi) == tan(3.0*pi*x)
assert cot(3.0*x*pi) == cot(3.0*pi*x)
assert cos(4.5*x*pi) == cos(4.5*pi*x)
assert sin(4.5*x*pi) == sin(4.5*pi*x)
assert tan(4.5*x*pi) == tan(4.5*pi*x)
assert cot(4.5*x*pi) == cot(4.5*pi*x)
def test_inverses():
raises(AttributeError, lambda: sin(x).inverse())
raises(AttributeError, lambda: cos(x).inverse())
assert tan(x).inverse() == atan
assert cot(x).inverse() == acot
raises(AttributeError, lambda: csc(x).inverse())
raises(AttributeError, lambda: sec(x).inverse())
assert asin(x).inverse() == sin
assert acos(x).inverse() == cos
assert atan(x).inverse() == tan
assert acot(x).inverse() == cot
def test_real_imag():
a, b = symbols('a b', real=True)
z = a + b*I
for deep in [True, False]:
assert sin(
z).as_real_imag(deep=deep) == (sin(a)*cosh(b), cos(a)*sinh(b))
assert cos(
z).as_real_imag(deep=deep) == (cos(a)*cosh(b), -sin(a)*sinh(b))
assert tan(z).as_real_imag(deep=deep) == (sin(2*a)/(cos(2*a) +
cosh(2*b)), sinh(2*b)/(cos(2*a) + cosh(2*b)))
assert cot(z).as_real_imag(deep=deep) == (-sin(2*a)/(cos(2*a) -
cosh(2*b)), sinh(2*b)/(cos(2*a) - cosh(2*b)))
assert sin(a).as_real_imag(deep=deep) == (sin(a), 0)
assert cos(a).as_real_imag(deep=deep) == (cos(a), 0)
assert tan(a).as_real_imag(deep=deep) == (tan(a), 0)
assert cot(a).as_real_imag(deep=deep) == (cot(a), 0)
@XFAIL
def test_sin_cos_with_infinity():
# Test for issue 5196
# https://github.com/sympy/sympy/issues/5196
assert sin(oo) is S.NaN
assert cos(oo) is S.NaN
@slow
def test_sincos_rewrite_sqrt():
# equivalent to testing rewrite(pow)
for p in [1, 3, 5, 17]:
for t in [1, 8]:
n = t*p
# The vertices `exp(i*pi/n)` of a regular `n`-gon can
# be expressed by means of nested square roots if and
# only if `n` is a product of Fermat primes, `p`, and
# powers of 2, `t'. The code aims to check all vertices
# not belonging to an `m`-gon for `m < n`(`gcd(i, n) == 1`).
# For large `n` this makes the test too slow, therefore
# the vertices are limited to those of index `i < 10`.
for i in range(1, min((n + 1)//2 + 1, 10)):
if 1 == gcd(i, n):
x = i*pi/n
s1 = sin(x).rewrite(sqrt)
c1 = cos(x).rewrite(sqrt)
assert not s1.has(cos, sin), "fails for %d*pi/%d" % (i, n)
assert not c1.has(cos, sin), "fails for %d*pi/%d" % (i, n)
assert 1e-3 > abs(sin(x.evalf(5)) - s1.evalf(2)), "fails for %d*pi/%d" % (i, n)
assert 1e-3 > abs(cos(x.evalf(5)) - c1.evalf(2)), "fails for %d*pi/%d" % (i, n)
assert cos(pi/14).rewrite(sqrt) == sqrt(cos(pi/7)/2 + S.Half)
assert cos(pi/257).rewrite(sqrt).evalf(64) == cos(pi/257).evalf(64)
assert cos(pi*Rational(-15, 2)/11, evaluate=False).rewrite(
sqrt) == -sqrt(-cos(pi*Rational(4, 11))/2 + S.Half)
assert cos(Mul(2, pi, S.Half, evaluate=False), evaluate=False).rewrite(
sqrt) == -1
e = cos(pi/3/17) # don't use pi/15 since that is caught at instantiation
a = (
-3*sqrt(-sqrt(17) + 17)*sqrt(sqrt(17) + 17)/64 -
3*sqrt(34)*sqrt(sqrt(17) + 17)/128 - sqrt(sqrt(17) +
17)*sqrt(-8*sqrt(2)*sqrt(sqrt(17) + 17) - sqrt(2)*sqrt(-sqrt(17) + 17)
+ sqrt(34)*sqrt(-sqrt(17) + 17) + 6*sqrt(17) + 34)/64 - sqrt(-sqrt(17)
+ 17)*sqrt(-8*sqrt(2)*sqrt(sqrt(17) + 17) - sqrt(2)*sqrt(-sqrt(17) +
17) + sqrt(34)*sqrt(-sqrt(17) + 17) + 6*sqrt(17) + 34)/128 - Rational(1, 32) +
sqrt(2)*sqrt(-8*sqrt(2)*sqrt(sqrt(17) + 17) - sqrt(2)*sqrt(-sqrt(17) +
17) + sqrt(34)*sqrt(-sqrt(17) + 17) + 6*sqrt(17) + 34)/64 +
3*sqrt(2)*sqrt(sqrt(17) + 17)/128 + sqrt(34)*sqrt(-sqrt(17) + 17)/128
+ 13*sqrt(2)*sqrt(-sqrt(17) + 17)/128 + sqrt(17)*sqrt(-sqrt(17) +
17)*sqrt(-8*sqrt(2)*sqrt(sqrt(17) + 17) - sqrt(2)*sqrt(-sqrt(17) + 17)
+ sqrt(34)*sqrt(-sqrt(17) + 17) + 6*sqrt(17) + 34)/128 + 5*sqrt(17)/32
+ sqrt(3)*sqrt(-sqrt(2)*sqrt(sqrt(17) + 17)*sqrt(sqrt(17)/32 +
sqrt(2)*sqrt(-sqrt(17) + 17)/32 +
sqrt(2)*sqrt(-8*sqrt(2)*sqrt(sqrt(17) + 17) - sqrt(2)*sqrt(-sqrt(17) +
17) + sqrt(34)*sqrt(-sqrt(17) + 17) + 6*sqrt(17) + 34)/32 + Rational(15, 32))/8 -
5*sqrt(2)*sqrt(sqrt(17)/32 + sqrt(2)*sqrt(-sqrt(17) + 17)/32 +
sqrt(2)*sqrt(-8*sqrt(2)*sqrt(sqrt(17) + 17) - sqrt(2)*sqrt(-sqrt(17) +
17) + sqrt(34)*sqrt(-sqrt(17) + 17) + 6*sqrt(17) + 34)/32 +
Rational(15, 32))*sqrt(-8*sqrt(2)*sqrt(sqrt(17) + 17) - sqrt(2)*sqrt(-sqrt(17) +
17) + sqrt(34)*sqrt(-sqrt(17) + 17) + 6*sqrt(17) + 34)/64 -
3*sqrt(2)*sqrt(-sqrt(17) + 17)*sqrt(sqrt(17)/32 +
sqrt(2)*sqrt(-sqrt(17) + 17)/32 +
sqrt(2)*sqrt(-8*sqrt(2)*sqrt(sqrt(17) + 17) - sqrt(2)*sqrt(-sqrt(17) +
17) + sqrt(34)*sqrt(-sqrt(17) + 17) + 6*sqrt(17) + 34)/32 + Rational(15, 32))/32
+ sqrt(34)*sqrt(sqrt(17)/32 + sqrt(2)*sqrt(-sqrt(17) + 17)/32 +
sqrt(2)*sqrt(-8*sqrt(2)*sqrt(sqrt(17) + 17) - sqrt(2)*sqrt(-sqrt(17) +
17) + sqrt(34)*sqrt(-sqrt(17) + 17) + 6*sqrt(17) + 34)/32 +
Rational(15, 32))*sqrt(-8*sqrt(2)*sqrt(sqrt(17) + 17) - sqrt(2)*sqrt(-sqrt(17) +
17) + sqrt(34)*sqrt(-sqrt(17) + 17) + 6*sqrt(17) + 34)/64 +
sqrt(sqrt(17)/32 + sqrt(2)*sqrt(-sqrt(17) + 17)/32 +
sqrt(2)*sqrt(-8*sqrt(2)*sqrt(sqrt(17) + 17) - sqrt(2)*sqrt(-sqrt(17) +
17) + sqrt(34)*sqrt(-sqrt(17) + 17) + 6*sqrt(17) + 34)/32 + Rational(15, 32))/2 +
S.Half + sqrt(-sqrt(17) + 17)*sqrt(sqrt(17)/32 + sqrt(2)*sqrt(-sqrt(17) +
17)/32 + sqrt(2)*sqrt(-8*sqrt(2)*sqrt(sqrt(17) + 17) -
sqrt(2)*sqrt(-sqrt(17) + 17) + sqrt(34)*sqrt(-sqrt(17) + 17) +
6*sqrt(17) + 34)/32 + Rational(15, 32))*sqrt(-8*sqrt(2)*sqrt(sqrt(17) + 17) -
sqrt(2)*sqrt(-sqrt(17) + 17) + sqrt(34)*sqrt(-sqrt(17) + 17) +
6*sqrt(17) + 34)/32 + sqrt(34)*sqrt(-sqrt(17) + 17)*sqrt(sqrt(17)/32 +
sqrt(2)*sqrt(-sqrt(17) + 17)/32 +
sqrt(2)*sqrt(-8*sqrt(2)*sqrt(sqrt(17) + 17) - sqrt(2)*sqrt(-sqrt(17) +
17) + sqrt(34)*sqrt(-sqrt(17) + 17) + 6*sqrt(17) + 34)/32 +
Rational(15, 32))/32)/2)
assert e.rewrite(sqrt) == a
assert e.n() == a.n()
# coverage of fermatCoords: multiplicity > 1; the following could be
# different but that portion of the code should be tested in some way
assert cos(pi/9/17).rewrite(sqrt) == \
sin(pi/9)*sin(pi*Rational(2, 17)) + cos(pi/9)*cos(pi*Rational(2, 17))
@slow
def test_tancot_rewrite_sqrt():
# equivalent to testing rewrite(pow)
for p in [1, 3, 5, 17]:
for t in [1, 8]:
n = t*p
for i in range(1, min((n + 1)//2 + 1, 10)):
if 1 == gcd(i, n):
x = i*pi/n
if 2*i != n and 3*i != 2*n:
t1 = tan(x).rewrite(sqrt)
assert not t1.has(cot, tan), "fails for %d*pi/%d" % (i, n)
assert 1e-3 > abs( tan(x.evalf(7)) - t1.evalf(4) ), "fails for %d*pi/%d" % (i, n)
if i != 0 and i != n:
c1 = cot(x).rewrite(sqrt)
assert not c1.has(cot, tan), "fails for %d*pi/%d" % (i, n)
assert 1e-3 > abs( cot(x.evalf(7)) - c1.evalf(4) ), "fails for %d*pi/%d" % (i, n)
def test_sec():
x = symbols('x', real=True)
z = symbols('z')
assert sec.nargs == FiniteSet(1)
assert sec(zoo) is nan
assert sec(0) == 1
assert sec(pi) == -1
assert sec(pi/2) is zoo
assert sec(-pi/2) is zoo
assert sec(pi/6) == 2*sqrt(3)/3
assert sec(pi/3) == 2
assert sec(pi*Rational(5, 2)) is zoo
assert sec(pi*Rational(9, 7)) == -sec(pi*Rational(2, 7))
assert sec(pi*Rational(3, 4)) == -sqrt(2) # issue 8421
assert sec(I) == 1/cosh(1)
assert sec(x*I) == 1/cosh(x)
assert sec(-x) == sec(x)
assert sec(asec(x)) == x
assert sec(z).conjugate() == sec(conjugate(z))
assert (sec(z).as_real_imag() ==
(cos(re(z))*cosh(im(z))/(sin(re(z))**2*sinh(im(z))**2 +
cos(re(z))**2*cosh(im(z))**2),
sin(re(z))*sinh(im(z))/(sin(re(z))**2*sinh(im(z))**2 +
cos(re(z))**2*cosh(im(z))**2)))
assert sec(x).expand(trig=True) == 1/cos(x)
assert sec(2*x).expand(trig=True) == 1/(2*cos(x)**2 - 1)
assert sec(x).is_extended_real == True
assert sec(z).is_real == None
assert sec(a).is_algebraic is None
assert sec(na).is_algebraic is False
assert sec(x).as_leading_term() == sec(x)
assert sec(0).is_finite == True
assert sec(x).is_finite == None
assert sec(pi/2).is_finite == False
assert series(sec(x), x, x0=0, n=6) == 1 + x**2/2 + 5*x**4/24 + O(x**6)
# https://github.com/sympy/sympy/issues/7166
assert series(sqrt(sec(x))) == 1 + x**2/4 + 7*x**4/96 + O(x**6)
# https://github.com/sympy/sympy/issues/7167
assert (series(sqrt(sec(x)), x, x0=pi*3/2, n=4) ==
1/sqrt(x - pi*Rational(3, 2)) + (x - pi*Rational(3, 2))**Rational(3, 2)/12 +
(x - pi*Rational(3, 2))**Rational(7, 2)/160 + O((x - pi*Rational(3, 2))**4, (x, pi*Rational(3, 2))))
assert sec(x).diff(x) == tan(x)*sec(x)
# Taylor Term checks
assert sec(z).taylor_term(4, z) == 5*z**4/24
assert sec(z).taylor_term(6, z) == 61*z**6/720
assert sec(z).taylor_term(5, z) == 0
def test_sec_rewrite():
assert sec(x).rewrite(exp) == 1/(exp(I*x)/2 + exp(-I*x)/2)
assert sec(x).rewrite(cos) == 1/cos(x)
assert sec(x).rewrite(tan) == (tan(x/2)**2 + 1)/(-tan(x/2)**2 + 1)
assert sec(x).rewrite(pow) == sec(x)
assert sec(x).rewrite(sqrt) == sec(x)
assert sec(z).rewrite(cot) == (cot(z/2)**2 + 1)/(cot(z/2)**2 - 1)
assert sec(x).rewrite(sin) == 1 / sin(x + pi / 2, evaluate=False)
assert sec(x).rewrite(tan) == (tan(x / 2)**2 + 1) / (-tan(x / 2)**2 + 1)
assert sec(x).rewrite(csc) == csc(-x + pi/2, evaluate=False)
def test_sec_fdiff():
assert sec(x).fdiff() == tan(x)*sec(x)
raises(ArgumentIndexError, lambda: sec(x).fdiff(2))
def test_csc():
x = symbols('x', real=True)
z = symbols('z')
# https://github.com/sympy/sympy/issues/6707
cosecant = csc('x')
alternate = 1/sin('x')
assert cosecant.equals(alternate) == True
assert alternate.equals(cosecant) == True
assert csc.nargs == FiniteSet(1)
assert csc(0) is zoo
assert csc(pi) is zoo
assert csc(zoo) is nan
assert csc(pi/2) == 1
assert csc(-pi/2) == -1
assert csc(pi/6) == 2
assert csc(pi/3) == 2*sqrt(3)/3
assert csc(pi*Rational(5, 2)) == 1
assert csc(pi*Rational(9, 7)) == -csc(pi*Rational(2, 7))
assert csc(pi*Rational(3, 4)) == sqrt(2) # issue 8421
assert csc(I) == -I/sinh(1)
assert csc(x*I) == -I/sinh(x)
assert csc(-x) == -csc(x)
assert csc(acsc(x)) == x
assert csc(z).conjugate() == csc(conjugate(z))
assert (csc(z).as_real_imag() ==
(sin(re(z))*cosh(im(z))/(sin(re(z))**2*cosh(im(z))**2 +
cos(re(z))**2*sinh(im(z))**2),
-cos(re(z))*sinh(im(z))/(sin(re(z))**2*cosh(im(z))**2 +
cos(re(z))**2*sinh(im(z))**2)))
assert csc(x).expand(trig=True) == 1/sin(x)
assert csc(2*x).expand(trig=True) == 1/(2*sin(x)*cos(x))
assert csc(x).is_extended_real == True
assert csc(z).is_real == None
assert csc(a).is_algebraic is None
assert csc(na).is_algebraic is False
assert csc(x).as_leading_term() == csc(x)
assert csc(0).is_finite == False
assert csc(x).is_finite == None
assert csc(pi/2).is_finite == True
assert series(csc(x), x, x0=pi/2, n=6) == \
1 + (x - pi/2)**2/2 + 5*(x - pi/2)**4/24 + O((x - pi/2)**6, (x, pi/2))
assert series(csc(x), x, x0=0, n=6) == \
1/x + x/6 + 7*x**3/360 + 31*x**5/15120 + O(x**6)
assert csc(x).diff(x) == -cot(x)*csc(x)
assert csc(x).taylor_term(2, x) == 0
assert csc(x).taylor_term(3, x) == 7*x**3/360
assert csc(x).taylor_term(5, x) == 31*x**5/15120
raises(ArgumentIndexError, lambda: csc(x).fdiff(2))
def test_asec():
z = Symbol('z', zero=True)
assert asec(z) is zoo
assert asec(nan) is nan
assert asec(1) == 0
assert asec(-1) == pi
assert asec(oo) == pi/2
assert asec(-oo) == pi/2
assert asec(zoo) == pi/2
assert asec(sec(pi*Rational(13, 4))) == pi*Rational(3, 4)
assert asec(1 + sqrt(5)) == pi*Rational(2, 5)
assert asec(2/sqrt(3)) == pi/6
assert asec(sqrt(4 - 2*sqrt(2))) == pi/8
assert asec(-sqrt(4 + 2*sqrt(2))) == pi*Rational(5, 8)
assert asec(sqrt(2 + 2*sqrt(5)/5)) == pi*Rational(3, 10)
assert asec(-sqrt(2 + 2*sqrt(5)/5)) == pi*Rational(7, 10)
assert asec(sqrt(2) - sqrt(6)) == pi*Rational(11, 12)
assert asec(x).diff(x) == 1/(x**2*sqrt(1 - 1/x**2))
assert asec(x).as_leading_term(x) == I*log(x)
assert asec(x).rewrite(log) == I*log(sqrt(1 - 1/x**2) + I/x) + pi/2
assert asec(x).rewrite(asin) == -asin(1/x) + pi/2
assert asec(x).rewrite(acos) == acos(1/x)
assert asec(x).rewrite(atan) == (2*atan(x + sqrt(x**2 - 1)) - pi/2)*sqrt(x**2)/x
assert asec(x).rewrite(acot) == (2*acot(x - sqrt(x**2 - 1)) - pi/2)*sqrt(x**2)/x
assert asec(x).rewrite(acsc) == -acsc(x) + pi/2
raises(ArgumentIndexError, lambda: asec(x).fdiff(2))
def test_asec_is_real():
assert asec(S.Half).is_real is False
n = Symbol('n', positive=True, integer=True)
assert asec(n).is_extended_real is True
assert asec(x).is_real is None
assert asec(r).is_real is None
t = Symbol('t', real=False, finite=True)
assert asec(t).is_real is False
def test_acsc():
assert acsc(nan) is nan
assert acsc(1) == pi/2
assert acsc(-1) == -pi/2
assert acsc(oo) == 0
assert acsc(-oo) == 0
assert acsc(zoo) == 0
assert acsc(0) is zoo
assert acsc(csc(3)) == -3 + pi
assert acsc(csc(4)) == -4 + pi
assert acsc(csc(6)) == 6 - 2*pi
assert unchanged(acsc, csc(x))
assert unchanged(acsc, sec(x))
assert acsc(2/sqrt(3)) == pi/3
assert acsc(csc(pi*Rational(13, 4))) == -pi/4
assert acsc(sqrt(2 + 2*sqrt(5)/5)) == pi/5
assert acsc(-sqrt(2 + 2*sqrt(5)/5)) == -pi/5
assert acsc(-2) == -pi/6
assert acsc(-sqrt(4 + 2*sqrt(2))) == -pi/8
assert acsc(sqrt(4 - 2*sqrt(2))) == pi*Rational(3, 8)
assert acsc(1 + sqrt(5)) == pi/10
assert acsc(sqrt(2) - sqrt(6)) == pi*Rational(-5, 12)
assert acsc(x).diff(x) == -1/(x**2*sqrt(1 - 1/x**2))
assert acsc(x).as_leading_term(x) == I*log(x)
assert acsc(x).rewrite(log) == -I*log(sqrt(1 - 1/x**2) + I/x)
assert acsc(x).rewrite(asin) == asin(1/x)
assert acsc(x).rewrite(acos) == -acos(1/x) + pi/2
assert acsc(x).rewrite(atan) == (-atan(sqrt(x**2 - 1)) + pi/2)*sqrt(x**2)/x
assert acsc(x).rewrite(acot) == (-acot(1/sqrt(x**2 - 1)) + pi/2)*sqrt(x**2)/x
assert acsc(x).rewrite(asec) == -asec(x) + pi/2
raises(ArgumentIndexError, lambda: acsc(x).fdiff(2))
def test_csc_rewrite():
assert csc(x).rewrite(pow) == csc(x)
assert csc(x).rewrite(sqrt) == csc(x)
assert csc(x).rewrite(exp) == 2*I/(exp(I*x) - exp(-I*x))
assert csc(x).rewrite(sin) == 1/sin(x)
assert csc(x).rewrite(tan) == (tan(x/2)**2 + 1)/(2*tan(x/2))
assert csc(x).rewrite(cot) == (cot(x/2)**2 + 1)/(2*cot(x/2))
assert csc(x).rewrite(cos) == 1/cos(x - pi/2, evaluate=False)
assert csc(x).rewrite(sec) == sec(-x + pi/2, evaluate=False)
# issue 17349
assert csc(1 - exp(-besselj(I, I))).rewrite(cos) == \
-1/cos(-pi/2 - 1 + cos(I*besselj(I, I)) +
I*cos(-pi/2 + I*besselj(I, I), evaluate=False), evaluate=False)
def test_inverses_nseries():
assert asin(x + 2)._eval_nseries(x, 4, None, I) == -asin(2) + pi + sqrt(3)*I*x/3 - sqrt(3)*I*x**2/9 + \
sqrt(3)*I*x**3/18 + O(x**4)
assert asin(x + 2)._eval_nseries(x, 4, None, -I) == asin(2) - sqrt(3)*I*x/3 + sqrt(3)*I*x**2/9 - sqrt(3)*I*x**3/18 + O(x**4)
assert asin(x - 2)._eval_nseries(x, 4, None, I) == -asin(2) - sqrt(3)*I*x/3 - sqrt(3)*I*x**2/9 - sqrt(3)*I*x**3/18 + O(x**4)
assert asin(x - 2)._eval_nseries(x, 4, None, -I) == asin(2) - pi + sqrt(3)*I*x/3 + sqrt(3)*I*x**2/9 + \
sqrt(3)*I*x**3/18 + O(x**4)
assert asin(I*x + I*x**3 + 2)._eval_nseries(x, 3, None, 1) == -asin(2) + pi - sqrt(3)*x/3 + sqrt(3)*I*x**2/9 + O(x**3)
assert asin(I*x + I*x**3 + 2)._eval_nseries(x, 3, None, -1) == asin(2) + sqrt(3)*x/3 - sqrt(3)*I*x**2/9 + O(x**3)
assert asin(I*x + I*x**3 - 2)._eval_nseries(x, 3, None, 1) == -asin(2) + sqrt(3)*x/3 + sqrt(3)*I*x**2/9 + O(x**3)
assert asin(I*x + I*x**3 - 2)._eval_nseries(x, 3, None, -1) == asin(2) - pi - sqrt(3)*x/3 - sqrt(3)*I*x**2/9 + O(x**3)
assert asin(I*x**2 + I*x**3 + 2)._eval_nseries(x, 3, None, 1) == -asin(2) + pi - sqrt(3)*x**2/3 + O(x**3)
assert asin(I*x**2 + I*x**3 + 2)._eval_nseries(x, 3, None, -1) == -asin(2) + pi - sqrt(3)*x**2/3 + O(x**3)
assert asin(I*x**2 + I*x**3 - 2)._eval_nseries(x, 3, None, 1) == -asin(2) + sqrt(3)*x**2/3 + O(x**3)
assert asin(I*x**2 + I*x**3 - 2)._eval_nseries(x, 3, None, -1) == -asin(2) + sqrt(3)*x**2/3 + O(x**3)
assert asin(1 + x)._eval_nseries(x, 3, None) == pi/2 - sqrt(2)*sqrt(-x) - \
sqrt(2)*(-x)**(S(3)/2)/12 - 3*sqrt(2)*(-x)**(S(5)/2)/160 + O(x**3)
assert asin(-1 + x)._eval_nseries(x, 3, None) == -pi/2 + sqrt(2)*sqrt(x) + \
sqrt(2)*x**(S(3)/2)/12 + 3*sqrt(2)*x**(S(5)/2)/160 + O(x**3)
assert asin(exp(x))._eval_nseries(x, 3, None) == pi/2 - sqrt(2)*sqrt(-x) + \
sqrt(2)*(-x)**(S(3)/2)/6 - sqrt(2)*(-x)**(S(5)/2)/120 + O(x**3)
assert asin(-exp(x))._eval_nseries(x, 3, None) == -pi/2 + sqrt(2)*sqrt(-x) - \
sqrt(2)*(-x)**(S(3)/2)/6 + sqrt(2)*(-x)**(S(5)/2)/120 + O(x**3)
assert acos(x + 2)._eval_nseries(x, 4, None, I) == -acos(2) - sqrt(3)*I*x/3 + sqrt(3)*I*x**2/9 - sqrt(3)*I*x**3/18 + O(x**4)
assert acos(x + 2)._eval_nseries(x, 4, None, -I) == acos(2) + sqrt(3)*I*x/3 - sqrt(3)*I*x**2/9 + sqrt(3)*I*x**3/18 + O(x**4)
assert acos(x - 2)._eval_nseries(x, 4, None, I) == acos(-2) + sqrt(3)*I*x/3 + sqrt(3)*I*x**2/9 + sqrt(3)*I*x**3/18 + O(x**4)
assert acos(x - 2)._eval_nseries(x, 4, None, -I) == -acos(-2) + 2*pi - sqrt(3)*I*x/3 - \
sqrt(3)*I*x**2/9 - sqrt(3)*I*x**3/18 + O(x**4)
# assert acos(I*x + I*x**3 + 2)._eval_nseries(x, 3, None, 1) == -acos(2) + sqrt(3)*x/3 - sqrt(3)*I*x**2/9 + O(x**3)
# assert acos(I*x + I*x**3 + 2)._eval_nseries(x, 3, None, -1) == acos(2) - sqrt(3)*x/3 + sqrt(3)*I*x**2/9 + O(x**3)
# assert acos(I*x + I*x**3 - 2)._eval_nseries(x, 3, None, 1) == acos(-2) - sqrt(3)*x/3 - sqrt(3)*I*x**2/9 + O(x**3)
# assert acos(I*x + I*x**3 - 2)._eval_nseries(x, 3, None, -1) == -acos(-2) + 2*pi + sqrt(3)*x/3 + sqrt(3)*I*x**2/9 + O(x**3)
# assert acos(I*x**2 + I*x**3 + 2)._eval_nseries(x, 3, None, 1) == -acos(2) + sqrt(3)*x**2/3 + O(x**3)
# assert acos(I*x**2 + I*x**3 + 2)._eval_nseries(x, 3, None, -1) == -acos(2) + sqrt(3)*x**2/3 + O(x**3)
# assert acos(I*x**2 + I*x**3 - 2)._eval_nseries(x, 3, None, 1) == acos(-2) - sqrt(3)*x**2/3 + O(x**3)
# assert acos(I*x**2 + I*x**3 - 2)._eval_nseries(x, 3, None, -1) == acos(-2) - sqrt(3)*x**2/3 + O(x**3)
# assert acos(1 + x)._eval_nseries(x, 3, None) == sqrt(2)*sqrt(-x) + sqrt(2)*(-x)**(S(3)/2)/12 + 3*sqrt(2)*(-x)**(S(5)/2)/160 + O(x**3)
# assert acos(-1 + x)._eval_nseries(x, 3, None) == pi - sqrt(2)*sqrt(x) - sqrt(2)*x**(S(3)/2)/12 - 3*sqrt(2)*x**(S(5)/2)/160 + O(x**3)
# assert acos(exp(x))._eval_nseries(x, 3, None) == sqrt(2)*sqrt(-x) - sqrt(2)*(-x)**(S(3)/2)/6 + sqrt(2)*(-x)**(S(5)/2)/120 + O(x**3)
# assert acos(-exp(x))._eval_nseries(x, 3, None) == pi - sqrt(2)*sqrt(-x) + sqrt(2)*(-x)**(S(3)/2)/6 - sqrt(2)*(-x)**(S(5)/2)/120 + O(x**3)
assert atan(x + 2*I)._eval_nseries(x, 4, None, 1) == I*atanh(2) - x/3 - 2*I*x**2/9 + 13*x**3/81 + O(x**4)
assert atan(x + 2*I)._eval_nseries(x, 4, None, -1) == I*atanh(2) - pi - x/3 - 2*I*x**2/9 + 13*x**3/81 + O(x**4)
assert atan(x - 2*I)._eval_nseries(x, 4, None, 1) == -I*atanh(2) + pi - x/3 + 2*I*x**2/9 + 13*x**3/81 + O(x**4)
assert atan(x - 2*I)._eval_nseries(x, 4, None, -1) == -I*atanh(2) - x/3 + 2*I*x**2/9 + 13*x**3/81 + O(x**4)
# assert atan(x**2 + 2*I)._eval_nseries(x, 3, None, 1) == I*atanh(2) - x**2/3 + O(x**3)
# assert atan(x**2 + 2*I)._eval_nseries(x, 3, None, -1) == I*atanh(2) - x**2/3 + O(x**3)
# assert atan(x**2 - 2*I)._eval_nseries(x, 3, None, 1) == -I*atanh(2) + pi - x**2/3 + O(x**3)
# assert atan(x**2 - 2*I)._eval_nseries(x, 3, None, -1) == -I*atanh(2) + pi - x**2/3 + O(x**3)
assert atan(1/x)._eval_nseries(x, 2, None, 1) == pi/2 - x + O(x**2)
assert atan(1/x)._eval_nseries(x, 2, None, -1) == -pi/2 - x + O(x**2)
assert acot(x + S(1)/2*I)._eval_nseries(x, 4, None, 1) == -I*acoth(S(1)/2) + pi - 4*x/3 + 8*I*x**2/9 + 112*x**3/81 + O(x**4)
assert acot(x + S(1)/2*I)._eval_nseries(x, 4, None, -1) == -I*acoth(S(1)/2) - 4*x/3 + 8*I*x**2/9 + 112*x**3/81 + O(x**4)
assert acot(x - S(1)/2*I)._eval_nseries(x, 4, None, 1) == I*acoth(S(1)/2) - 4*x/3 - 8*I*x**2/9 + 112*x**3/81 + O(x**4)
assert acot(x - S(1)/2*I)._eval_nseries(x, 4, None, -1) == I*acoth(S(1)/2) - pi - 4*x/3 - 8*I*x**2/9 + 112*x**3/81 + O(x**4)
# assert acot(x**2 + S(1)/2*I)._eval_nseries(x, 3, None, 1) == -I*acoth(S(1)/2) + pi - 4*x**2/3 + O(x**3)
# assert acot(x**2 + S(1)/2*I)._eval_nseries(x, 3, None, -1) == -I*acoth(S(1)/2) + pi - 4*x**2/3 + O(x**3)
# assert acot(x**2 - S(1)/2*I)._eval_nseries(x, 3, None, 1) == I*acoth(S(1)/2) - 4*x**2/3 + O(x**3)
# assert acot(x**2 - S(1)/2*I)._eval_nseries(x, 3, None, -1) == I*acoth(S(1)/2) - 4*x**2/3 + O(x**3)
# assert acot(x)._eval_nseries(x, 2, None, 1) == pi/2 - x + O(x**2)
# assert acot(x)._eval_nseries(x, 2, None, -1) == -pi/2 - x + O(x**2)
assert asec(x + S(1)/2)._eval_nseries(x, 4, None, I) == asec(S(1)/2) - 4*sqrt(3)*I*x/3 + \
8*sqrt(3)*I*x**2/9 - 16*sqrt(3)*I*x**3/9 + O(x**4)
assert asec(x + S(1)/2)._eval_nseries(x, 4, None, -I) == -asec(S(1)/2) + 4*sqrt(3)*I*x/3 - \
8*sqrt(3)*I*x**2/9 + 16*sqrt(3)*I*x**3/9 + O(x**4)
assert asec(x - S(1)/2)._eval_nseries(x, 4, None, I) == -asec(-S(1)/2) + 2*pi + 4*sqrt(3)*I*x/3 + \
8*sqrt(3)*I*x**2/9 + 16*sqrt(3)*I*x**3/9 + O(x**4)
assert asec(x - S(1)/2)._eval_nseries(x, 4, None, -I) == asec(-S(1)/2) - 4*sqrt(3)*I*x/3 - \
8*sqrt(3)*I*x**2/9 - 16*sqrt(3)*I*x**3/9 + O(x**4)
# assert asec(I*x + I*x**3 + S(1)/2)._eval_nseries(x, 3, None, 1) == asec(S(1)/2) + 4*sqrt(3)*x/3 - 8*sqrt(3)*I*x**2/9 + O(x**3)
# assert asec(I*x + I*x**3 + S(1)/2)._eval_nseries(x, 3, None, -1) == -asec(S(1)/2) - 4*sqrt(3)*x/3 + 8*sqrt(3)*I*x**2/9 + O(x**3)
# assert asec(I*x + I*x**3 - S(1)/2)._eval_nseries(x, 3, None, 1) == -asec(-S(1)/2) + 2*pi - 4*sqrt(3)*x/3 - 8*sqrt(3)*I*x**2/9 + O(x**3)
# assert asec(I*x + I*x**3 - S(1)/2)._eval_nseries(x, 3, None, -1) == asec(-S(1)/2) + 4*sqrt(3)*x/3 + 8*sqrt(3)*I*x**2/9 + O(x**3)
# assert asec(I*x**2 + I*x**3 + S(1)/2)._eval_nseries(x, 3, None, 1) == asec(S(1)/2) + 4*sqrt(3)*x**2/3 + O(x**3)
# assert asec(I*x**2 + I*x**3 + S(1)/2)._eval_nseries(x, 3, None, -1) == asec(S(1)/2) + 4*sqrt(3)*x**2/3 + O(x**3)
# assert asec(I*x**2 + I*x**3 - S(1)/2)._eval_nseries(x, 3, None, 1) == -asec(-S(1)/2) + 2*pi - 4*sqrt(3)*x**2/3 + O(x**3)
# assert asec(I*x**2 + I*x**3 - S(1)/2)._eval_nseries(x, 3, None, -1) == -asec(-S(1)/2) + 2*pi - 4*sqrt(3)*x**2/3 + O(x**3)
# assert asec(1 + x)._eval_nseries(x, 3, None) == sqrt(2)*sqrt(x) - 5*sqrt(2)*x**(S(3)/2)/12 + 43*sqrt(2)*x**(S(5)/2)/160 + O(x**3)
# assert asec(-1 + x)._eval_nseries(x, 3, None) == pi - sqrt(2)*sqrt(-x) + 5*sqrt(2)*(-x)**(S(3)/2)/12 - 43*sqrt(2)*(-x)**(S(5)/2)/160 + O(x**3)
# assert asec(exp(x))._eval_nseries(x, 3, None) == sqrt(2)*sqrt(x) - sqrt(2)*x**(S(3)/2)/6 + sqrt(2)*x**(S(5)/2)/120 + O(x**3)
# assert asec(-exp(x))._eval_nseries(x, 3, None) == pi - sqrt(2)*sqrt(x) + sqrt(2)*x**(S(3)/2)/6 - sqrt(2)*x**(S(5)/2)/120 + O(x**3)
assert acsc(x + S(1)/2)._eval_nseries(x, 4, None, I) == acsc(S(1)/2) + 4*sqrt(3)*I*x/3 - \
8*sqrt(3)*I*x**2/9 + 16*sqrt(3)*I*x**3/9 + O(x**4)
assert acsc(x + S(1)/2)._eval_nseries(x, 4, None, -I) == -acsc(S(1)/2) + pi - 4*sqrt(3)*I*x/3 + \
8*sqrt(3)*I*x**2/9 - 16*sqrt(3)*I*x**3/9 + O(x**4)
assert acsc(x - S(1)/2)._eval_nseries(x, 4, None, I) == acsc(S(1)/2) - pi - 4*sqrt(3)*I*x/3 - \
8*sqrt(3)*I*x**2/9 - 16*sqrt(3)*I*x**3/9 + O(x**4)
assert acsc(x - S(1)/2)._eval_nseries(x, 4, None, -I) == -acsc(S(1)/2) + 4*sqrt(3)*I*x/3 + \
8*sqrt(3)*I*x**2/9 + 16*sqrt(3)*I*x**3/9 + O(x**4)
# assert acsc(I*x + I*x**3 + S(1)/2)._eval_nseries(x, 3, None, 1) == acsc(S(1)/2) - 4*sqrt(3)*x/3 + 8*sqrt(3)*I*x**2/9 + O(x**3)
# assert acsc(I*x + I*x**3 + S(1)/2)._eval_nseries(x, 3, None, -1) == -acsc(S(1)/2) + pi + 4*sqrt(3)*x/3 - 8*sqrt(3)*I*x**2/9 + O(x**3)
# assert acsc(I*x + I*x**3 - S(1)/2)._eval_nseries(x, 3, None, 1) == acsc(S(1)/2) - pi + 4*sqrt(3)*x/3 + 8*sqrt(3)*I*x**2/9 + O(x**3)
# assert acsc(I*x + I*x**3 - S(1)/2)._eval_nseries(x, 3, None, -1) == -acsc(S(1)/2) - 4*sqrt(3)*x/3 - 8*sqrt(3)*I*x**2/9 + O(x**3)
# assert acsc(I*x**2 + I*x**3 + S(1)/2)._eval_nseries(x, 3, None, 1) == acsc(S(1)/2) - 4*sqrt(3)*x**2/3 + O(x**3)
# assert acsc(I*x**2 + I*x**3 + S(1)/2)._eval_nseries(x, 3, None, -1) == acsc(S(1)/2) - 4*sqrt(3)*x**2/3 + O(x**3)
# assert acsc(I*x**2 + I*x**3 - S(1)/2)._eval_nseries(x, 3, None, 1) == acsc(S(1)/2) - pi + 4*sqrt(3)*x**2/3 + O(x**3)
# assert acsc(I*x**2 + I*x**3 - S(1)/2)._eval_nseries(x, 3, None, -1) == acsc(S(1)/2) - pi + 4*sqrt(3)*x**2/3 + O(x**3)
# assert acsc(1 + x)._eval_nseries(x, 3, None) == pi/2 - sqrt(2)*sqrt(x) + 5*sqrt(2)*x**(S(3)/2)/12 - 43*sqrt(2)*x**(S(5)/2)/160 + O(x**3)
# assert acsc(-1 + x)._eval_nseries(x, 3, None) == -pi/2 + sqrt(2)*sqrt(-x) - 5*sqrt(2)*(-x)**(S(3)/2)/12 + 43*sqrt(2)*(-x)**(S(5)/2)/160 + O(x**3)
# assert acsc(exp(x))._eval_nseries(x, 3, None) == pi/2 - sqrt(2)*sqrt(x) + sqrt(2)*x**(S(3)/2)/6 - sqrt(2)*x**(S(5)/2)/120 + O(x**3)
# assert acsc(-exp(x))._eval_nseries(x, 3, None) == -pi/2 + sqrt(2)*sqrt(x) - sqrt(2)*x**(S(3)/2)/6 + sqrt(2)*x**(S(5)/2)/120 + O(x**3)
def test_issue_8653():
n = Symbol('n', integer=True)
assert sin(n).is_irrational is None
assert cos(n).is_irrational is None
assert tan(n).is_irrational is None
def test_issue_9157():
n = Symbol('n', integer=True, positive=True)
assert atan(n - 1).is_nonnegative is True
def test_trig_period():
x, y = symbols('x, y')
assert sin(x).period() == 2*pi
assert cos(x).period() == 2*pi
assert tan(x).period() == pi
assert cot(x).period() == pi
assert sec(x).period() == 2*pi
assert csc(x).period() == 2*pi
assert sin(2*x).period() == pi
assert cot(4*x - 6).period() == pi/4
assert cos((-3)*x).period() == pi*Rational(2, 3)
assert cos(x*y).period(x) == 2*pi/abs(y)
assert sin(3*x*y + 2*pi).period(y) == 2*pi/abs(3*x)
assert tan(3*x).period(y) is S.Zero
raises(NotImplementedError, lambda: sin(x**2).period(x))
def test_issue_7171():
assert sin(x).rewrite(sqrt) == sin(x)
assert sin(x).rewrite(pow) == sin(x)
def test_issue_11864():
w, k = symbols('w, k', real=True)
F = Piecewise((1, Eq(2*pi*k, 0)), (sin(pi*k)/(pi*k), True))
soln = Piecewise((1, Eq(2*pi*k, 0)), (sinc(pi*k), True))
assert F.rewrite(sinc) == soln
def test_real_assumptions():
z = Symbol('z', real=False, finite=True)
assert sin(z).is_real is None
assert cos(z).is_real is None
assert tan(z).is_real is False
assert sec(z).is_real is None
assert csc(z).is_real is None
assert cot(z).is_real is False
assert asin(p).is_real is None
assert asin(n).is_real is None
assert asec(p).is_real is None
assert asec(n).is_real is None
assert acos(p).is_real is None
assert acos(n).is_real is None
assert acsc(p).is_real is None
assert acsc(n).is_real is None
assert atan(p).is_positive is True
assert atan(n).is_negative is True
assert acot(p).is_positive is True
assert acot(n).is_negative is True
def test_issue_14320():
assert asin(sin(2)) == -2 + pi and (-pi/2 <= -2 + pi <= pi/2) and sin(2) == sin(-2 + pi)
assert asin(cos(2)) == -2 + pi/2 and (-pi/2 <= -2 + pi/2 <= pi/2) and cos(2) == sin(-2 + pi/2)
assert acos(sin(2)) == -pi/2 + 2 and (0 <= -pi/2 + 2 <= pi) and sin(2) == cos(-pi/2 + 2)
assert acos(cos(20)) == -6*pi + 20 and (0 <= -6*pi + 20 <= pi) and cos(20) == cos(-6*pi + 20)
assert acos(cos(30)) == -30 + 10*pi and (0 <= -30 + 10*pi <= pi) and cos(30) == cos(-30 + 10*pi)
assert atan(tan(17)) == -5*pi + 17 and (-pi/2 < -5*pi + 17 < pi/2) and tan(17) == tan(-5*pi + 17)
assert atan(tan(15)) == -5*pi + 15 and (-pi/2 < -5*pi + 15 < pi/2) and tan(15) == tan(-5*pi + 15)
assert atan(cot(12)) == -12 + pi*Rational(7, 2) and (-pi/2 < -12 + pi*Rational(7, 2) < pi/2) and cot(12) == tan(-12 + pi*Rational(7, 2))
assert acot(cot(15)) == -5*pi + 15 and (-pi/2 < -5*pi + 15 <= pi/2) and cot(15) == cot(-5*pi + 15)
assert acot(tan(19)) == -19 + pi*Rational(13, 2) and (-pi/2 < -19 + pi*Rational(13, 2) <= pi/2) and tan(19) == cot(-19 + pi*Rational(13, 2))
assert asec(sec(11)) == -11 + 4*pi and (0 <= -11 + 4*pi <= pi) and cos(11) == cos(-11 + 4*pi)
assert asec(csc(13)) == -13 + pi*Rational(9, 2) and (0 <= -13 + pi*Rational(9, 2) <= pi) and sin(13) == cos(-13 + pi*Rational(9, 2))
assert acsc(csc(14)) == -4*pi + 14 and (-pi/2 <= -4*pi + 14 <= pi/2) and sin(14) == sin(-4*pi + 14)
assert acsc(sec(10)) == pi*Rational(-7, 2) + 10 and (-pi/2 <= pi*Rational(-7, 2) + 10 <= pi/2) and cos(10) == sin(pi*Rational(-7, 2) + 10)
def test_issue_14543():
assert sec(2*pi + 11) == sec(11)
assert sec(2*pi - 11) == sec(11)
assert sec(pi + 11) == -sec(11)
assert sec(pi - 11) == -sec(11)
assert csc(2*pi + 17) == csc(17)
assert csc(2*pi - 17) == -csc(17)
assert csc(pi + 17) == -csc(17)
assert csc(pi - 17) == csc(17)
x = Symbol('x')
assert csc(pi/2 + x) == sec(x)
assert csc(pi/2 - x) == sec(x)
assert csc(pi*Rational(3, 2) + x) == -sec(x)
assert csc(pi*Rational(3, 2) - x) == -sec(x)
assert sec(pi/2 - x) == csc(x)
assert sec(pi/2 + x) == -csc(x)
assert sec(pi*Rational(3, 2) + x) == csc(x)
assert sec(pi*Rational(3, 2) - x) == -csc(x)
def test_as_real_imag():
# This is for https://github.com/sympy/sympy/issues/17142
# If it start failing again in irrelevant builds or in the master
# please open up the issue again.
expr = atan(I/(I + I*tan(1)))
assert expr.as_real_imag() == (expr, 0)
def test_issue_18746():
e3 = cos(S.Pi*(x/4 + 1/4))
assert e3.period() == 8
|
dc20e092188165e2198691b46152c8b63d63a0da672b31e388ec877ba89030d0 | from sympy import (
Abs, acos, adjoint, arg, atan, atan2, conjugate, cos, DiracDelta,
E, exp, expand, Expr, Function, Heaviside, I, im, log, nan, oo,
pi, Rational, re, S, sign, sin, sqrt, Symbol, symbols, transpose,
zoo, exp_polar, Piecewise, Interval, comp, Integral, Matrix,
ImmutableMatrix, SparseMatrix, ImmutableSparseMatrix, MatrixSymbol,
FunctionMatrix, Lambda, Derivative, Eq)
from sympy.core.expr import unchanged
from sympy.core.function import ArgumentIndexError
from sympy.testing.pytest import XFAIL, raises, _both_exp_pow
def N_equals(a, b):
"""Check whether two complex numbers are numerically close"""
return comp(a.n(), b.n(), 1.e-6)
def test_re():
x, y = symbols('x,y')
a, b = symbols('a,b', real=True)
r = Symbol('r', real=True)
i = Symbol('i', imaginary=True)
assert re(nan) is nan
assert re(oo) is oo
assert re(-oo) is -oo
assert re(0) == 0
assert re(1) == 1
assert re(-1) == -1
assert re(E) == E
assert re(-E) == -E
assert unchanged(re, x)
assert re(x*I) == -im(x)
assert re(r*I) == 0
assert re(r) == r
assert re(i*I) == I * i
assert re(i) == 0
assert re(x + y) == re(x) + re(y)
assert re(x + r) == re(x) + r
assert re(re(x)) == re(x)
assert re(2 + I) == 2
assert re(x + I) == re(x)
assert re(x + y*I) == re(x) - im(y)
assert re(x + r*I) == re(x)
assert re(log(2*I)) == log(2)
assert re((2 + I)**2).expand(complex=True) == 3
assert re(conjugate(x)) == re(x)
assert conjugate(re(x)) == re(x)
assert re(x).as_real_imag() == (re(x), 0)
assert re(i*r*x).diff(r) == re(i*x)
assert re(i*r*x).diff(i) == I*r*im(x)
assert re(
sqrt(a + b*I)) == (a**2 + b**2)**Rational(1, 4)*cos(atan2(b, a)/2)
assert re(a * (2 + b*I)) == 2*a
assert re((1 + sqrt(a + b*I))/2) == \
(a**2 + b**2)**Rational(1, 4)*cos(atan2(b, a)/2)/2 + S.Half
assert re(x).rewrite(im) == x - S.ImaginaryUnit*im(x)
assert (x + re(y)).rewrite(re, im) == x + y - S.ImaginaryUnit*im(y)
a = Symbol('a', algebraic=True)
t = Symbol('t', transcendental=True)
x = Symbol('x')
assert re(a).is_algebraic
assert re(x).is_algebraic is None
assert re(t).is_algebraic is False
assert re(S.ComplexInfinity) is S.NaN
n, m, l = symbols('n m l')
A = MatrixSymbol('A',n,m)
assert re(A) == (S.Half) * (A + conjugate(A))
A = Matrix([[1 + 4*I,2],[0, -3*I]])
assert re(A) == Matrix([[1, 2],[0, 0]])
A = ImmutableMatrix([[1 + 3*I, 3-2*I],[0, 2*I]])
assert re(A) == ImmutableMatrix([[1, 3],[0, 0]])
X = SparseMatrix([[2*j + i*I for i in range(5)] for j in range(5)])
assert re(X) - Matrix([[0, 0, 0, 0, 0],
[2, 2, 2, 2, 2],
[4, 4, 4, 4, 4],
[6, 6, 6, 6, 6],
[8, 8, 8, 8, 8]]) == Matrix.zeros(5)
assert im(X) - Matrix([[0, 1, 2, 3, 4],
[0, 1, 2, 3, 4],
[0, 1, 2, 3, 4],
[0, 1, 2, 3, 4],
[0, 1, 2, 3, 4]]) == Matrix.zeros(5)
X = FunctionMatrix(3, 3, Lambda((n, m), n + m*I))
assert re(X) == Matrix([[0, 0, 0], [1, 1, 1], [2, 2, 2]])
def test_im():
x, y = symbols('x,y')
a, b = symbols('a,b', real=True)
r = Symbol('r', real=True)
i = Symbol('i', imaginary=True)
assert im(nan) is nan
assert im(oo*I) is oo
assert im(-oo*I) is -oo
assert im(0) == 0
assert im(1) == 0
assert im(-1) == 0
assert im(E*I) == E
assert im(-E*I) == -E
assert unchanged(im, x)
assert im(x*I) == re(x)
assert im(r*I) == r
assert im(r) == 0
assert im(i*I) == 0
assert im(i) == -I * i
assert im(x + y) == im(x) + im(y)
assert im(x + r) == im(x)
assert im(x + r*I) == im(x) + r
assert im(im(x)*I) == im(x)
assert im(2 + I) == 1
assert im(x + I) == im(x) + 1
assert im(x + y*I) == im(x) + re(y)
assert im(x + r*I) == im(x) + r
assert im(log(2*I)) == pi/2
assert im((2 + I)**2).expand(complex=True) == 4
assert im(conjugate(x)) == -im(x)
assert conjugate(im(x)) == im(x)
assert im(x).as_real_imag() == (im(x), 0)
assert im(i*r*x).diff(r) == im(i*x)
assert im(i*r*x).diff(i) == -I * re(r*x)
assert im(
sqrt(a + b*I)) == (a**2 + b**2)**Rational(1, 4)*sin(atan2(b, a)/2)
assert im(a * (2 + b*I)) == a*b
assert im((1 + sqrt(a + b*I))/2) == \
(a**2 + b**2)**Rational(1, 4)*sin(atan2(b, a)/2)/2
assert im(x).rewrite(re) == -S.ImaginaryUnit * (x - re(x))
assert (x + im(y)).rewrite(im, re) == x - S.ImaginaryUnit * (y - re(y))
a = Symbol('a', algebraic=True)
t = Symbol('t', transcendental=True)
x = Symbol('x')
assert re(a).is_algebraic
assert re(x).is_algebraic is None
assert re(t).is_algebraic is False
assert im(S.ComplexInfinity) is S.NaN
n, m, l = symbols('n m l')
A = MatrixSymbol('A',n,m)
assert im(A) == (S.One/(2*I)) * (A - conjugate(A))
A = Matrix([[1 + 4*I, 2],[0, -3*I]])
assert im(A) == Matrix([[4, 0],[0, -3]])
A = ImmutableMatrix([[1 + 3*I, 3-2*I],[0, 2*I]])
assert im(A) == ImmutableMatrix([[3, -2],[0, 2]])
X = ImmutableSparseMatrix(
[[i*I + i for i in range(5)] for i in range(5)])
Y = SparseMatrix([[i for i in range(5)] for i in range(5)])
assert im(X).as_immutable() == Y
X = FunctionMatrix(3, 3, Lambda((n, m), n + m*I))
assert im(X) == Matrix([[0, 1, 2], [0, 1, 2], [0, 1, 2]])
def test_sign():
assert sign(1.2) == 1
assert sign(-1.2) == -1
assert sign(3*I) == I
assert sign(-3*I) == -I
assert sign(0) == 0
assert sign(nan) is nan
assert sign(2 + 2*I).doit() == sqrt(2)*(2 + 2*I)/4
assert sign(2 + 3*I).simplify() == sign(2 + 3*I)
assert sign(2 + 2*I).simplify() == sign(1 + I)
assert sign(im(sqrt(1 - sqrt(3)))) == 1
assert sign(sqrt(1 - sqrt(3))) == I
x = Symbol('x')
assert sign(x).is_finite is True
assert sign(x).is_complex is True
assert sign(x).is_imaginary is None
assert sign(x).is_integer is None
assert sign(x).is_real is None
assert sign(x).is_zero is None
assert sign(x).doit() == sign(x)
assert sign(1.2*x) == sign(x)
assert sign(2*x) == sign(x)
assert sign(I*x) == I*sign(x)
assert sign(-2*I*x) == -I*sign(x)
assert sign(conjugate(x)) == conjugate(sign(x))
p = Symbol('p', positive=True)
n = Symbol('n', negative=True)
m = Symbol('m', negative=True)
assert sign(2*p*x) == sign(x)
assert sign(n*x) == -sign(x)
assert sign(n*m*x) == sign(x)
x = Symbol('x', imaginary=True)
assert sign(x).is_imaginary is True
assert sign(x).is_integer is False
assert sign(x).is_real is False
assert sign(x).is_zero is False
assert sign(x).diff(x) == 2*DiracDelta(-I*x)
assert sign(x).doit() == x / Abs(x)
assert conjugate(sign(x)) == -sign(x)
x = Symbol('x', real=True)
assert sign(x).is_imaginary is False
assert sign(x).is_integer is True
assert sign(x).is_real is True
assert sign(x).is_zero is None
assert sign(x).diff(x) == 2*DiracDelta(x)
assert sign(x).doit() == sign(x)
assert conjugate(sign(x)) == sign(x)
x = Symbol('x', nonzero=True)
assert sign(x).is_imaginary is False
assert sign(x).is_integer is True
assert sign(x).is_real is True
assert sign(x).is_zero is False
assert sign(x).doit() == x / Abs(x)
assert sign(Abs(x)) == 1
assert Abs(sign(x)) == 1
x = Symbol('x', positive=True)
assert sign(x).is_imaginary is False
assert sign(x).is_integer is True
assert sign(x).is_real is True
assert sign(x).is_zero is False
assert sign(x).doit() == x / Abs(x)
assert sign(Abs(x)) == 1
assert Abs(sign(x)) == 1
x = 0
assert sign(x).is_imaginary is False
assert sign(x).is_integer is True
assert sign(x).is_real is True
assert sign(x).is_zero is True
assert sign(x).doit() == 0
assert sign(Abs(x)) == 0
assert Abs(sign(x)) == 0
nz = Symbol('nz', nonzero=True, integer=True)
assert sign(nz).is_imaginary is False
assert sign(nz).is_integer is True
assert sign(nz).is_real is True
assert sign(nz).is_zero is False
assert sign(nz)**2 == 1
assert (sign(nz)**3).args == (sign(nz), 3)
assert sign(Symbol('x', nonnegative=True)).is_nonnegative
assert sign(Symbol('x', nonnegative=True)).is_nonpositive is None
assert sign(Symbol('x', nonpositive=True)).is_nonnegative is None
assert sign(Symbol('x', nonpositive=True)).is_nonpositive
assert sign(Symbol('x', real=True)).is_nonnegative is None
assert sign(Symbol('x', real=True)).is_nonpositive is None
assert sign(Symbol('x', real=True, zero=False)).is_nonpositive is None
x, y = Symbol('x', real=True), Symbol('y')
f = Function('f')
assert sign(x).rewrite(Piecewise) == \
Piecewise((1, x > 0), (-1, x < 0), (0, True))
assert sign(y).rewrite(Piecewise) == sign(y)
assert sign(x).rewrite(Heaviside) == 2*Heaviside(x, H0=S(1)/2) - 1
assert sign(y).rewrite(Heaviside) == sign(y)
assert sign(y).rewrite(Abs) == Piecewise((0, Eq(y, 0)), (y/Abs(y), True))
assert sign(f(y)).rewrite(Abs) == Piecewise((0, Eq(f(y), 0)), (f(y)/Abs(f(y)), True))
# evaluate what can be evaluated
assert sign(exp_polar(I*pi)*pi) is S.NegativeOne
eq = -sqrt(10 + 6*sqrt(3)) + sqrt(1 + sqrt(3)) + sqrt(3 + 3*sqrt(3))
# if there is a fast way to know when and when you cannot prove an
# expression like this is zero then the equality to zero is ok
assert sign(eq).func is sign or sign(eq) == 0
# but sometimes it's hard to do this so it's better not to load
# abs down with tests that will be very slow
q = 1 + sqrt(2) - 2*sqrt(3) + 1331*sqrt(6)
p = expand(q**3)**Rational(1, 3)
d = p - q
assert sign(d).func is sign or sign(d) == 0
def test_as_real_imag():
n = pi**1000
# the special code for working out the real
# and complex parts of a power with Integer exponent
# should not run if there is no imaginary part, hence
# this should not hang
assert n.as_real_imag() == (n, 0)
# issue 6261
x = Symbol('x')
assert sqrt(x).as_real_imag() == \
((re(x)**2 + im(x)**2)**Rational(1, 4)*cos(atan2(im(x), re(x))/2),
(re(x)**2 + im(x)**2)**Rational(1, 4)*sin(atan2(im(x), re(x))/2))
# issue 3853
a, b = symbols('a,b', real=True)
assert ((1 + sqrt(a + b*I))/2).as_real_imag() == \
(
(a**2 + b**2)**Rational(
1, 4)*cos(atan2(b, a)/2)/2 + S.Half,
(a**2 + b**2)**Rational(1, 4)*sin(atan2(b, a)/2)/2)
assert sqrt(a**2).as_real_imag() == (sqrt(a**2), 0)
i = symbols('i', imaginary=True)
assert sqrt(i**2).as_real_imag() == (0, abs(i))
assert ((1 + I)/(1 - I)).as_real_imag() == (0, 1)
assert ((1 + I)**3/(1 - I)).as_real_imag() == (-2, 0)
@XFAIL
def test_sign_issue_3068():
n = pi**1000
i = int(n)
x = Symbol('x')
assert (n - i).round() == 1 # doesn't hang
assert sign(n - i) == 1
# perhaps it's not possible to get the sign right when
# only 1 digit is being requested for this situation;
# 2 digits works
assert (n - x).n(1, subs={x: i}) > 0
assert (n - x).n(2, subs={x: i}) > 0
def test_Abs():
raises(TypeError, lambda: Abs(Interval(2, 3))) # issue 8717
x, y = symbols('x,y')
assert sign(sign(x)) == sign(x)
assert sign(x*y).func is sign
assert Abs(0) == 0
assert Abs(1) == 1
assert Abs(-1) == 1
assert Abs(I) == 1
assert Abs(-I) == 1
assert Abs(nan) is nan
assert Abs(zoo) is oo
assert Abs(I * pi) == pi
assert Abs(-I * pi) == pi
assert Abs(I * x) == Abs(x)
assert Abs(-I * x) == Abs(x)
assert Abs(-2*x) == 2*Abs(x)
assert Abs(-2.0*x) == 2.0*Abs(x)
assert Abs(2*pi*x*y) == 2*pi*Abs(x*y)
assert Abs(conjugate(x)) == Abs(x)
assert conjugate(Abs(x)) == Abs(x)
assert Abs(x).expand(complex=True) == sqrt(re(x)**2 + im(x)**2)
a = Symbol('a', positive=True)
assert Abs(2*pi*x*a) == 2*pi*a*Abs(x)
assert Abs(2*pi*I*x*a) == 2*pi*a*Abs(x)
x = Symbol('x', real=True)
n = Symbol('n', integer=True)
assert Abs((-1)**n) == 1
assert x**(2*n) == Abs(x)**(2*n)
assert Abs(x).diff(x) == sign(x)
assert abs(x) == Abs(x) # Python built-in
assert Abs(x)**3 == x**2*Abs(x)
assert Abs(x)**4 == x**4
assert (
Abs(x)**(3*n)).args == (Abs(x), 3*n) # leave symbolic odd unchanged
assert (1/Abs(x)).args == (Abs(x), -1)
assert 1/Abs(x)**3 == 1/(x**2*Abs(x))
assert Abs(x)**-3 == Abs(x)/(x**4)
assert Abs(x**3) == x**2*Abs(x)
assert Abs(I**I) == exp(-pi/2)
assert Abs((4 + 5*I)**(6 + 7*I)) == 68921*exp(-7*atan(Rational(5, 4)))
y = Symbol('y', real=True)
assert Abs(I**y) == 1
y = Symbol('y')
assert Abs(I**y) == exp(-pi*im(y)/2)
x = Symbol('x', imaginary=True)
assert Abs(x).diff(x) == -sign(x)
eq = -sqrt(10 + 6*sqrt(3)) + sqrt(1 + sqrt(3)) + sqrt(3 + 3*sqrt(3))
# if there is a fast way to know when you can and when you cannot prove an
# expression like this is zero then the equality to zero is ok
assert abs(eq).func is Abs or abs(eq) == 0
# but sometimes it's hard to do this so it's better not to load
# abs down with tests that will be very slow
q = 1 + sqrt(2) - 2*sqrt(3) + 1331*sqrt(6)
p = expand(q**3)**Rational(1, 3)
d = p - q
assert abs(d).func is Abs or abs(d) == 0
assert Abs(4*exp(pi*I/4)) == 4
assert Abs(3**(2 + I)) == 9
assert Abs((-3)**(1 - I)) == 3*exp(pi)
assert Abs(oo) is oo
assert Abs(-oo) is oo
assert Abs(oo + I) is oo
assert Abs(oo + I*oo) is oo
a = Symbol('a', algebraic=True)
t = Symbol('t', transcendental=True)
x = Symbol('x')
assert re(a).is_algebraic
assert re(x).is_algebraic is None
assert re(t).is_algebraic is False
assert Abs(x).fdiff() == sign(x)
raises(ArgumentIndexError, lambda: Abs(x).fdiff(2))
# doesn't have recursion error
arg = sqrt(acos(1 - I)*acos(1 + I))
assert abs(arg) == arg
# special handling to put Abs in denom
assert abs(1/x) == 1/Abs(x)
e = abs(2/x**2)
assert e.is_Mul and e == 2/Abs(x**2)
assert unchanged(Abs, y/x)
assert unchanged(Abs, x/(x + 1))
assert unchanged(Abs, x*y)
p = Symbol('p', positive=True)
assert abs(x/p) == abs(x)/p
# coverage
assert unchanged(Abs, Symbol('x', real=True)**y)
# issue 19627
f = Function('f', positive=True)
assert sqrt(f(x)**2) == f(x)
# issue 21625
assert unchanged(Abs, S("im(acos(-i + acosh(-g + i)))"))
def test_Abs_rewrite():
x = Symbol('x', real=True)
a = Abs(x).rewrite(Heaviside).expand()
assert a == x*Heaviside(x) - x*Heaviside(-x)
for i in [-2, -1, 0, 1, 2]:
assert a.subs(x, i) == abs(i)
y = Symbol('y')
assert Abs(y).rewrite(Heaviside) == Abs(y)
x, y = Symbol('x', real=True), Symbol('y')
assert Abs(x).rewrite(Piecewise) == Piecewise((x, x >= 0), (-x, True))
assert Abs(y).rewrite(Piecewise) == Abs(y)
assert Abs(y).rewrite(sign) == y/sign(y)
i = Symbol('i', imaginary=True)
assert abs(i).rewrite(Piecewise) == Piecewise((I*i, I*i >= 0), (-I*i, True))
assert Abs(y).rewrite(conjugate) == sqrt(y*conjugate(y))
assert Abs(i).rewrite(conjugate) == sqrt(-i**2) # == -I*i
y = Symbol('y', extended_real=True)
assert (Abs(exp(-I*x)-exp(-I*y))**2).rewrite(conjugate) == \
-exp(I*x)*exp(-I*y) + 2 - exp(-I*x)*exp(I*y)
def test_Abs_real():
# test some properties of abs that only apply
# to real numbers
x = Symbol('x', complex=True)
assert sqrt(x**2) != Abs(x)
assert Abs(x**2) != x**2
x = Symbol('x', real=True)
assert sqrt(x**2) == Abs(x)
assert Abs(x**2) == x**2
# if the symbol is zero, the following will still apply
nn = Symbol('nn', nonnegative=True, real=True)
np = Symbol('np', nonpositive=True, real=True)
assert Abs(nn) == nn
assert Abs(np) == -np
def test_Abs_properties():
x = Symbol('x')
assert Abs(x).is_real is None
assert Abs(x).is_extended_real is True
assert Abs(x).is_rational is None
assert Abs(x).is_positive is None
assert Abs(x).is_nonnegative is None
assert Abs(x).is_extended_positive is None
assert Abs(x).is_extended_nonnegative is True
f = Symbol('x', finite=True)
assert Abs(f).is_real is True
assert Abs(f).is_extended_real is True
assert Abs(f).is_rational is None
assert Abs(f).is_positive is None
assert Abs(f).is_nonnegative is True
assert Abs(f).is_extended_positive is None
assert Abs(f).is_extended_nonnegative is True
z = Symbol('z', complex=True, zero=False)
assert Abs(z).is_real is True # since complex implies finite
assert Abs(z).is_extended_real is True
assert Abs(z).is_rational is None
assert Abs(z).is_positive is True
assert Abs(z).is_extended_positive is True
assert Abs(z).is_zero is False
p = Symbol('p', positive=True)
assert Abs(p).is_real is True
assert Abs(p).is_extended_real is True
assert Abs(p).is_rational is None
assert Abs(p).is_positive is True
assert Abs(p).is_zero is False
q = Symbol('q', rational=True)
assert Abs(q).is_real is True
assert Abs(q).is_rational is True
assert Abs(q).is_integer is None
assert Abs(q).is_positive is None
assert Abs(q).is_nonnegative is True
i = Symbol('i', integer=True)
assert Abs(i).is_real is True
assert Abs(i).is_integer is True
assert Abs(i).is_positive is None
assert Abs(i).is_nonnegative is True
e = Symbol('n', even=True)
ne = Symbol('ne', real=True, even=False)
assert Abs(e).is_even is True
assert Abs(ne).is_even is False
assert Abs(i).is_even is None
o = Symbol('n', odd=True)
no = Symbol('no', real=True, odd=False)
assert Abs(o).is_odd is True
assert Abs(no).is_odd is False
assert Abs(i).is_odd is None
def test_abs():
# this tests that abs calls Abs; don't rename to
# test_Abs since that test is already above
a = Symbol('a', positive=True)
assert abs(I*(1 + a)**2) == (1 + a)**2
def test_arg():
assert arg(0) is nan
assert arg(1) == 0
assert arg(-1) == pi
assert arg(I) == pi/2
assert arg(-I) == -pi/2
assert arg(1 + I) == pi/4
assert arg(-1 + I) == pi*Rational(3, 4)
assert arg(1 - I) == -pi/4
assert arg(exp_polar(4*pi*I)) == 4*pi
assert arg(exp_polar(-7*pi*I)) == -7*pi
assert arg(exp_polar(5 - 3*pi*I/4)) == pi*Rational(-3, 4)
f = Function('f')
assert not arg(f(0) + I*f(1)).atoms(re)
x = Symbol('x')
p = Function('p', extended_positive=True)
assert arg(p(x)) == 0
assert arg((3 + I)*p(x)) == arg(3 + I)
p = Symbol('p', positive=True)
assert arg(p) == 0
n = Symbol('n', negative=True)
assert arg(n) == pi
x = Symbol('x')
assert conjugate(arg(x)) == arg(x)
e = p + I*p**2
assert arg(e) == arg(1 + p*I)
# make sure sign doesn't swap
e = -2*p + 4*I*p**2
assert arg(e) == arg(-1 + 2*p*I)
# make sure sign isn't lost
x = symbols('x', real=True) # could be zero
e = x + I*x
assert arg(e) == arg(x*(1 + I))
assert arg(e/p) == arg(x*(1 + I))
e = p*cos(p) + I*log(p)*exp(p)
assert arg(e).args[0] == e
# keep it simple -- let the user do more advanced cancellation
e = (p + 1) + I*(p**2 - 1)
assert arg(e).args[0] == e
f = Function('f')
e = 2*x*(f(0) - 1) - 2*x*f(0)
assert arg(e) == arg(-2*x)
assert arg(f(0)).func == arg and arg(f(0)).args == (f(0),)
def test_arg_rewrite():
assert arg(1 + I) == atan2(1, 1)
x = Symbol('x', real=True)
y = Symbol('y', real=True)
assert arg(x + I*y).rewrite(atan2) == atan2(y, x)
def test_adjoint():
a = Symbol('a', antihermitian=True)
b = Symbol('b', hermitian=True)
assert adjoint(a) == -a
assert adjoint(I*a) == I*a
assert adjoint(b) == b
assert adjoint(I*b) == -I*b
assert adjoint(a*b) == -b*a
assert adjoint(I*a*b) == I*b*a
x, y = symbols('x y')
assert adjoint(adjoint(x)) == x
assert adjoint(x + y) == adjoint(x) + adjoint(y)
assert adjoint(x - y) == adjoint(x) - adjoint(y)
assert adjoint(x * y) == adjoint(x) * adjoint(y)
assert adjoint(x / y) == adjoint(x) / adjoint(y)
assert adjoint(-x) == -adjoint(x)
x, y = symbols('x y', commutative=False)
assert adjoint(adjoint(x)) == x
assert adjoint(x + y) == adjoint(x) + adjoint(y)
assert adjoint(x - y) == adjoint(x) - adjoint(y)
assert adjoint(x * y) == adjoint(y) * adjoint(x)
assert adjoint(x / y) == 1 / adjoint(y) * adjoint(x)
assert adjoint(-x) == -adjoint(x)
def test_conjugate():
a = Symbol('a', real=True)
b = Symbol('b', imaginary=True)
assert conjugate(a) == a
assert conjugate(I*a) == -I*a
assert conjugate(b) == -b
assert conjugate(I*b) == I*b
assert conjugate(a*b) == -a*b
assert conjugate(I*a*b) == I*a*b
x, y = symbols('x y')
assert conjugate(conjugate(x)) == x
assert conjugate(x + y) == conjugate(x) + conjugate(y)
assert conjugate(x - y) == conjugate(x) - conjugate(y)
assert conjugate(x * y) == conjugate(x) * conjugate(y)
assert conjugate(x / y) == conjugate(x) / conjugate(y)
assert conjugate(-x) == -conjugate(x)
a = Symbol('a', algebraic=True)
t = Symbol('t', transcendental=True)
assert re(a).is_algebraic
assert re(x).is_algebraic is None
assert re(t).is_algebraic is False
def test_conjugate_transpose():
x = Symbol('x')
assert conjugate(transpose(x)) == adjoint(x)
assert transpose(conjugate(x)) == adjoint(x)
assert adjoint(transpose(x)) == conjugate(x)
assert transpose(adjoint(x)) == conjugate(x)
assert adjoint(conjugate(x)) == transpose(x)
assert conjugate(adjoint(x)) == transpose(x)
class Symmetric(Expr):
def _eval_adjoint(self):
return None
def _eval_conjugate(self):
return None
def _eval_transpose(self):
return self
x = Symmetric()
assert conjugate(x) == adjoint(x)
assert transpose(x) == x
def test_transpose():
a = Symbol('a', complex=True)
assert transpose(a) == a
assert transpose(I*a) == I*a
x, y = symbols('x y')
assert transpose(transpose(x)) == x
assert transpose(x + y) == transpose(x) + transpose(y)
assert transpose(x - y) == transpose(x) - transpose(y)
assert transpose(x * y) == transpose(x) * transpose(y)
assert transpose(x / y) == transpose(x) / transpose(y)
assert transpose(-x) == -transpose(x)
x, y = symbols('x y', commutative=False)
assert transpose(transpose(x)) == x
assert transpose(x + y) == transpose(x) + transpose(y)
assert transpose(x - y) == transpose(x) - transpose(y)
assert transpose(x * y) == transpose(y) * transpose(x)
assert transpose(x / y) == 1 / transpose(y) * transpose(x)
assert transpose(-x) == -transpose(x)
@_both_exp_pow
def test_polarify():
from sympy import polar_lift, polarify
x = Symbol('x')
z = Symbol('z', polar=True)
f = Function('f')
ES = {}
assert polarify(-1) == (polar_lift(-1), ES)
assert polarify(1 + I) == (polar_lift(1 + I), ES)
assert polarify(exp(x), subs=False) == exp(x)
assert polarify(1 + x, subs=False) == 1 + x
assert polarify(f(I) + x, subs=False) == f(polar_lift(I)) + x
assert polarify(x, lift=True) == polar_lift(x)
assert polarify(z, lift=True) == z
assert polarify(f(x), lift=True) == f(polar_lift(x))
assert polarify(1 + x, lift=True) == polar_lift(1 + x)
assert polarify(1 + f(x), lift=True) == polar_lift(1 + f(polar_lift(x)))
newex, subs = polarify(f(x) + z)
assert newex.subs(subs) == f(x) + z
mu = Symbol("mu")
sigma = Symbol("sigma", positive=True)
# Make sure polarify(lift=True) doesn't try to lift the integration
# variable
assert polarify(
Integral(sqrt(2)*x*exp(-(-mu + x)**2/(2*sigma**2))/(2*sqrt(pi)*sigma),
(x, -oo, oo)), lift=True) == Integral(sqrt(2)*(sigma*exp_polar(0))**exp_polar(I*pi)*
exp((sigma*exp_polar(0))**(2*exp_polar(I*pi))*exp_polar(I*pi)*polar_lift(-mu + x)**
(2*exp_polar(0))/2)*exp_polar(0)*polar_lift(x)/(2*sqrt(pi)), (x, -oo, oo))
def test_unpolarify():
from sympy import (exp_polar, polar_lift, exp, unpolarify,
principal_branch)
from sympy import gamma, erf, sin, tanh, uppergamma, Eq, Ne
from sympy.abc import x
p = exp_polar(7*I) + 1
u = exp(7*I) + 1
assert unpolarify(1) == 1
assert unpolarify(p) == u
assert unpolarify(p**2) == u**2
assert unpolarify(p**x) == p**x
assert unpolarify(p*x) == u*x
assert unpolarify(p + x) == u + x
assert unpolarify(sqrt(sin(p))) == sqrt(sin(u))
# Test reduction to principal branch 2*pi.
t = principal_branch(x, 2*pi)
assert unpolarify(t) == x
assert unpolarify(sqrt(t)) == sqrt(t)
# Test exponents_only.
assert unpolarify(p**p, exponents_only=True) == p**u
assert unpolarify(uppergamma(x, p**p)) == uppergamma(x, p**u)
# Test functions.
assert unpolarify(sin(p)) == sin(u)
assert unpolarify(tanh(p)) == tanh(u)
assert unpolarify(gamma(p)) == gamma(u)
assert unpolarify(erf(p)) == erf(u)
assert unpolarify(uppergamma(x, p)) == uppergamma(x, p)
assert unpolarify(uppergamma(sin(p), sin(p + exp_polar(0)))) == \
uppergamma(sin(u), sin(u + 1))
assert unpolarify(uppergamma(polar_lift(0), 2*exp_polar(0))) == \
uppergamma(0, 2)
assert unpolarify(Eq(p, 0)) == Eq(u, 0)
assert unpolarify(Ne(p, 0)) == Ne(u, 0)
assert unpolarify(polar_lift(x) > 0) == (x > 0)
# Test bools
assert unpolarify(True) is True
def test_issue_4035():
x = Symbol('x')
assert Abs(x).expand(trig=True) == Abs(x)
assert sign(x).expand(trig=True) == sign(x)
assert arg(x).expand(trig=True) == arg(x)
def test_issue_3206():
x = Symbol('x')
assert Abs(Abs(x)) == Abs(x)
def test_issue_4754_derivative_conjugate():
x = Symbol('x', real=True)
y = Symbol('y', imaginary=True)
f = Function('f')
assert (f(x).conjugate()).diff(x) == (f(x).diff(x)).conjugate()
assert (f(y).conjugate()).diff(y) == -(f(y).diff(y)).conjugate()
def test_derivatives_issue_4757():
x = Symbol('x', real=True)
y = Symbol('y', imaginary=True)
f = Function('f')
assert re(f(x)).diff(x) == re(f(x).diff(x))
assert im(f(x)).diff(x) == im(f(x).diff(x))
assert re(f(y)).diff(y) == -I*im(f(y).diff(y))
assert im(f(y)).diff(y) == -I*re(f(y).diff(y))
assert Abs(f(x)).diff(x).subs(f(x), 1 + I*x).doit() == x/sqrt(1 + x**2)
assert arg(f(x)).diff(x).subs(f(x), 1 + I*x**2).doit() == 2*x/(1 + x**4)
assert Abs(f(y)).diff(y).subs(f(y), 1 + y).doit() == -y/sqrt(1 - y**2)
assert arg(f(y)).diff(y).subs(f(y), I + y**2).doit() == 2*y/(1 + y**4)
def test_issue_11413():
from sympy import Matrix, simplify
v0 = Symbol('v0')
v1 = Symbol('v1')
v2 = Symbol('v2')
V = Matrix([[v0],[v1],[v2]])
U = V.normalized()
assert U == Matrix([
[v0/sqrt(Abs(v0)**2 + Abs(v1)**2 + Abs(v2)**2)],
[v1/sqrt(Abs(v0)**2 + Abs(v1)**2 + Abs(v2)**2)],
[v2/sqrt(Abs(v0)**2 + Abs(v1)**2 + Abs(v2)**2)]])
U.norm = sqrt(v0**2/(v0**2 + v1**2 + v2**2) + v1**2/(v0**2 + v1**2 + v2**2) + v2**2/(v0**2 + v1**2 + v2**2))
assert simplify(U.norm) == 1
def test_periodic_argument():
from sympy import (periodic_argument, unbranched_argument, oo,
principal_branch, polar_lift, pi)
x = Symbol('x')
p = Symbol('p', positive=True)
assert unbranched_argument(2 + I) == periodic_argument(2 + I, oo)
assert unbranched_argument(1 + x) == periodic_argument(1 + x, oo)
assert N_equals(unbranched_argument((1 + I)**2), pi/2)
assert N_equals(unbranched_argument((1 - I)**2), -pi/2)
assert N_equals(periodic_argument((1 + I)**2, 3*pi), pi/2)
assert N_equals(periodic_argument((1 - I)**2, 3*pi), -pi/2)
assert unbranched_argument(principal_branch(x, pi)) == \
periodic_argument(x, pi)
assert unbranched_argument(polar_lift(2 + I)) == unbranched_argument(2 + I)
assert periodic_argument(polar_lift(2 + I), 2*pi) == \
periodic_argument(2 + I, 2*pi)
assert periodic_argument(polar_lift(2 + I), 3*pi) == \
periodic_argument(2 + I, 3*pi)
assert periodic_argument(polar_lift(2 + I), pi) == \
periodic_argument(polar_lift(2 + I), pi)
assert unbranched_argument(polar_lift(1 + I)) == pi/4
assert periodic_argument(2*p, p) == periodic_argument(p, p)
assert periodic_argument(pi*p, p) == periodic_argument(p, p)
assert Abs(polar_lift(1 + I)) == Abs(1 + I)
@XFAIL
def test_principal_branch_fail():
# TODO XXX why does abs(x)._eval_evalf() not fall back to global evalf?
from sympy import principal_branch
assert N_equals(principal_branch((1 + I)**2, pi/2), 0)
def test_principal_branch():
from sympy import principal_branch, polar_lift, exp_polar
p = Symbol('p', positive=True)
x = Symbol('x')
neg = Symbol('x', negative=True)
assert principal_branch(polar_lift(x), p) == principal_branch(x, p)
assert principal_branch(polar_lift(2 + I), p) == principal_branch(2 + I, p)
assert principal_branch(2*x, p) == 2*principal_branch(x, p)
assert principal_branch(1, pi) == exp_polar(0)
assert principal_branch(-1, 2*pi) == exp_polar(I*pi)
assert principal_branch(-1, pi) == exp_polar(0)
assert principal_branch(exp_polar(3*pi*I)*x, 2*pi) == \
principal_branch(exp_polar(I*pi)*x, 2*pi)
assert principal_branch(neg*exp_polar(pi*I), 2*pi) == neg*exp_polar(-I*pi)
# related to issue #14692
assert principal_branch(exp_polar(-I*pi/2)/polar_lift(neg), 2*pi) == \
exp_polar(-I*pi/2)/neg
assert N_equals(principal_branch((1 + I)**2, 2*pi), 2*I)
assert N_equals(principal_branch((1 + I)**2, 3*pi), 2*I)
assert N_equals(principal_branch((1 + I)**2, 1*pi), 2*I)
# test argument sanitization
assert principal_branch(x, I).func is principal_branch
assert principal_branch(x, -4).func is principal_branch
assert principal_branch(x, -oo).func is principal_branch
assert principal_branch(x, zoo).func is principal_branch
@XFAIL
def test_issue_6167_6151():
n = pi**1000
i = int(n)
assert sign(n - i) == 1
assert abs(n - i) == n - i
x = Symbol('x')
eps = pi**-1500
big = pi**1000
one = cos(x)**2 + sin(x)**2
e = big*one - big + eps
from sympy import simplify
assert sign(simplify(e)) == 1
for xi in (111, 11, 1, Rational(1, 10)):
assert sign(e.subs(x, xi)) == 1
def test_issue_14216():
from sympy.functions.elementary.complexes import unpolarify
A = MatrixSymbol("A", 2, 2)
assert unpolarify(A[0, 0]) == A[0, 0]
assert unpolarify(A[0, 0]*A[1, 0]) == A[0, 0]*A[1, 0]
def test_issue_14238():
# doesn't cause recursion error
r = Symbol('r', real=True)
assert Abs(r + Piecewise((0, r > 0), (1 - r, True)))
def test_zero_assumptions():
nr = Symbol('nonreal', real=False, finite=True)
ni = Symbol('nonimaginary', imaginary=False)
# imaginary implies not zero
nzni = Symbol('nonzerononimaginary', zero=False, imaginary=False)
assert re(nr).is_zero is None
assert im(nr).is_zero is False
assert re(ni).is_zero is None
assert im(ni).is_zero is None
assert re(nzni).is_zero is False
assert im(nzni).is_zero is None
@_both_exp_pow
def test_issue_15893():
f = Function('f', real=True)
x = Symbol('x', real=True)
eq = Derivative(Abs(f(x)), f(x))
assert eq.doit() == sign(f(x))
|
dbedcedb5060eb7c26af5ad1507fae3a7b86255fc7a7eb66497526bc1d2b20af | import itertools as it
from sympy.core.expr import unchanged
from sympy.core.function import Function
from sympy.core.numbers import I, oo, Rational
from sympy.core.power import Pow
from sympy.core.singleton import S
from sympy.core.symbol import Symbol
from sympy.external import import_module
from sympy.functions.elementary.exponential import log
from sympy.functions.elementary.integers import floor, ceiling
from sympy.functions.elementary.miscellaneous import (sqrt, cbrt, root, Min,
Max, real_root)
from sympy.functions.elementary.trigonometric import cos, sin
from sympy.functions.special.delta_functions import Heaviside
from sympy.utilities.lambdify import lambdify
from sympy.testing.pytest import raises, skip, ignore_warnings
def test_Min():
from sympy.abc import x, y, z
n = Symbol('n', negative=True)
n_ = Symbol('n_', negative=True)
nn = Symbol('nn', nonnegative=True)
nn_ = Symbol('nn_', nonnegative=True)
p = Symbol('p', positive=True)
p_ = Symbol('p_', positive=True)
np = Symbol('np', nonpositive=True)
np_ = Symbol('np_', nonpositive=True)
r = Symbol('r', real=True)
assert Min(5, 4) == 4
assert Min(-oo, -oo) is -oo
assert Min(-oo, n) is -oo
assert Min(n, -oo) is -oo
assert Min(-oo, np) is -oo
assert Min(np, -oo) is -oo
assert Min(-oo, 0) is -oo
assert Min(0, -oo) is -oo
assert Min(-oo, nn) is -oo
assert Min(nn, -oo) is -oo
assert Min(-oo, p) is -oo
assert Min(p, -oo) is -oo
assert Min(-oo, oo) is -oo
assert Min(oo, -oo) is -oo
assert Min(n, n) == n
assert unchanged(Min, n, np)
assert Min(np, n) == Min(n, np)
assert Min(n, 0) == n
assert Min(0, n) == n
assert Min(n, nn) == n
assert Min(nn, n) == n
assert Min(n, p) == n
assert Min(p, n) == n
assert Min(n, oo) == n
assert Min(oo, n) == n
assert Min(np, np) == np
assert Min(np, 0) == np
assert Min(0, np) == np
assert Min(np, nn) == np
assert Min(nn, np) == np
assert Min(np, p) == np
assert Min(p, np) == np
assert Min(np, oo) == np
assert Min(oo, np) == np
assert Min(0, 0) == 0
assert Min(0, nn) == 0
assert Min(nn, 0) == 0
assert Min(0, p) == 0
assert Min(p, 0) == 0
assert Min(0, oo) == 0
assert Min(oo, 0) == 0
assert Min(nn, nn) == nn
assert unchanged(Min, nn, p)
assert Min(p, nn) == Min(nn, p)
assert Min(nn, oo) == nn
assert Min(oo, nn) == nn
assert Min(p, p) == p
assert Min(p, oo) == p
assert Min(oo, p) == p
assert Min(oo, oo) is oo
assert Min(n, n_).func is Min
assert Min(nn, nn_).func is Min
assert Min(np, np_).func is Min
assert Min(p, p_).func is Min
# lists
assert Min() is S.Infinity
assert Min(x) == x
assert Min(x, y) == Min(y, x)
assert Min(x, y, z) == Min(z, y, x)
assert Min(x, Min(y, z)) == Min(z, y, x)
assert Min(x, Max(y, -oo)) == Min(x, y)
assert Min(p, oo, n, p, p, p_) == n
assert Min(p_, n_, p) == n_
assert Min(n, oo, -7, p, p, 2) == Min(n, -7)
assert Min(2, x, p, n, oo, n_, p, 2, -2, -2) == Min(-2, x, n, n_)
assert Min(0, x, 1, y) == Min(0, x, y)
assert Min(1000, 100, -100, x, p, n) == Min(n, x, -100)
assert unchanged(Min, sin(x), cos(x))
assert Min(sin(x), cos(x)) == Min(cos(x), sin(x))
assert Min(cos(x), sin(x)).subs(x, 1) == cos(1)
assert Min(cos(x), sin(x)).subs(x, S.Half) == sin(S.Half)
raises(ValueError, lambda: Min(cos(x), sin(x)).subs(x, I))
raises(ValueError, lambda: Min(I))
raises(ValueError, lambda: Min(I, x))
raises(ValueError, lambda: Min(S.ComplexInfinity, x))
assert Min(1, x).diff(x) == Heaviside(1 - x)
assert Min(x, 1).diff(x) == Heaviside(1 - x)
assert Min(0, -x, 1 - 2*x).diff(x) == -Heaviside(x + Min(0, -2*x + 1)) \
- 2*Heaviside(2*x + Min(0, -x) - 1)
# issue 7619
f = Function('f')
assert Min(1, 2*Min(f(1), 2)) # doesn't fail
# issue 7233
e = Min(0, x)
assert e.n().args == (0, x)
# issue 8643
m = Min(n, p_, n_, r)
assert m.is_positive is False
assert m.is_nonnegative is False
assert m.is_negative is True
m = Min(p, p_)
assert m.is_positive is True
assert m.is_nonnegative is True
assert m.is_negative is False
m = Min(p, nn_, p_)
assert m.is_positive is None
assert m.is_nonnegative is True
assert m.is_negative is False
m = Min(nn, p, r)
assert m.is_positive is None
assert m.is_nonnegative is None
assert m.is_negative is None
def test_Max():
from sympy.abc import x, y, z
n = Symbol('n', negative=True)
n_ = Symbol('n_', negative=True)
nn = Symbol('nn', nonnegative=True)
p = Symbol('p', positive=True)
p_ = Symbol('p_', positive=True)
r = Symbol('r', real=True)
assert Max(5, 4) == 5
# lists
assert Max() is S.NegativeInfinity
assert Max(x) == x
assert Max(x, y) == Max(y, x)
assert Max(x, y, z) == Max(z, y, x)
assert Max(x, Max(y, z)) == Max(z, y, x)
assert Max(x, Min(y, oo)) == Max(x, y)
assert Max(n, -oo, n_, p, 2) == Max(p, 2)
assert Max(n, -oo, n_, p) == p
assert Max(2, x, p, n, -oo, S.NegativeInfinity, n_, p, 2) == Max(2, x, p)
assert Max(0, x, 1, y) == Max(1, x, y)
assert Max(r, r + 1, r - 1) == 1 + r
assert Max(1000, 100, -100, x, p, n) == Max(p, x, 1000)
assert Max(cos(x), sin(x)) == Max(sin(x), cos(x))
assert Max(cos(x), sin(x)).subs(x, 1) == sin(1)
assert Max(cos(x), sin(x)).subs(x, S.Half) == cos(S.Half)
raises(ValueError, lambda: Max(cos(x), sin(x)).subs(x, I))
raises(ValueError, lambda: Max(I))
raises(ValueError, lambda: Max(I, x))
raises(ValueError, lambda: Max(S.ComplexInfinity, 1))
assert Max(n, -oo, n_, p, 2) == Max(p, 2)
assert Max(n, -oo, n_, p, 1000) == Max(p, 1000)
assert Max(1, x).diff(x) == Heaviside(x - 1)
assert Max(x, 1).diff(x) == Heaviside(x - 1)
assert Max(x**2, 1 + x, 1).diff(x) == \
2*x*Heaviside(x**2 - Max(1, x + 1)) \
+ Heaviside(x - Max(1, x**2) + 1)
e = Max(0, x)
assert e.n().args == (0, x)
# issue 8643
m = Max(p, p_, n, r)
assert m.is_positive is True
assert m.is_nonnegative is True
assert m.is_negative is False
m = Max(n, n_)
assert m.is_positive is False
assert m.is_nonnegative is False
assert m.is_negative is True
m = Max(n, n_, r)
assert m.is_positive is None
assert m.is_nonnegative is None
assert m.is_negative is None
m = Max(n, nn, r)
assert m.is_positive is None
assert m.is_nonnegative is True
assert m.is_negative is False
def test_minmax_assumptions():
r = Symbol('r', real=True)
a = Symbol('a', real=True, algebraic=True)
t = Symbol('t', real=True, transcendental=True)
q = Symbol('q', rational=True)
p = Symbol('p', irrational=True)
n = Symbol('n', rational=True, integer=False)
i = Symbol('i', integer=True)
o = Symbol('o', odd=True)
e = Symbol('e', even=True)
k = Symbol('k', prime=True)
reals = [r, a, t, q, p, n, i, o, e, k]
for ext in (Max, Min):
for x, y in it.product(reals, repeat=2):
# Must be real
assert ext(x, y).is_real
# Algebraic?
if x.is_algebraic and y.is_algebraic:
assert ext(x, y).is_algebraic
elif x.is_transcendental and y.is_transcendental:
assert ext(x, y).is_transcendental
else:
assert ext(x, y).is_algebraic is None
# Rational?
if x.is_rational and y.is_rational:
assert ext(x, y).is_rational
elif x.is_irrational and y.is_irrational:
assert ext(x, y).is_irrational
else:
assert ext(x, y).is_rational is None
# Integer?
if x.is_integer and y.is_integer:
assert ext(x, y).is_integer
elif x.is_noninteger and y.is_noninteger:
assert ext(x, y).is_noninteger
else:
assert ext(x, y).is_integer is None
# Odd?
if x.is_odd and y.is_odd:
assert ext(x, y).is_odd
elif x.is_odd is False and y.is_odd is False:
assert ext(x, y).is_odd is False
else:
assert ext(x, y).is_odd is None
# Even?
if x.is_even and y.is_even:
assert ext(x, y).is_even
elif x.is_even is False and y.is_even is False:
assert ext(x, y).is_even is False
else:
assert ext(x, y).is_even is None
# Prime?
if x.is_prime and y.is_prime:
assert ext(x, y).is_prime
elif x.is_prime is False and y.is_prime is False:
assert ext(x, y).is_prime is False
else:
assert ext(x, y).is_prime is None
def test_issue_8413():
x = Symbol('x', real=True)
# we can't evaluate in general because non-reals are not
# comparable: Min(floor(3.2 + I), 3.2 + I) -> ValueError
assert Min(floor(x), x) == floor(x)
assert Min(ceiling(x), x) == x
assert Max(floor(x), x) == x
assert Max(ceiling(x), x) == ceiling(x)
def test_root():
from sympy.abc import x
n = Symbol('n', integer=True)
k = Symbol('k', integer=True)
assert root(2, 2) == sqrt(2)
assert root(2, 1) == 2
assert root(2, 3) == 2**Rational(1, 3)
assert root(2, 3) == cbrt(2)
assert root(2, -5) == 2**Rational(4, 5)/2
assert root(-2, 1) == -2
assert root(-2, 2) == sqrt(2)*I
assert root(-2, 1) == -2
assert root(x, 2) == sqrt(x)
assert root(x, 1) == x
assert root(x, 3) == x**Rational(1, 3)
assert root(x, 3) == cbrt(x)
assert root(x, -5) == x**Rational(-1, 5)
assert root(x, n) == x**(1/n)
assert root(x, -n) == x**(-1/n)
assert root(x, n, k) == (-1)**(2*k/n)*x**(1/n)
def test_real_root():
assert real_root(-8, 3) == -2
assert real_root(-16, 4) == root(-16, 4)
r = root(-7, 4)
assert real_root(r) == r
r1 = root(-1, 3)
r2 = r1**2
r3 = root(-1, 4)
assert real_root(r1 + r2 + r3) == -1 + r2 + r3
assert real_root(root(-2, 3)) == -root(2, 3)
assert real_root(-8., 3) == -2
x = Symbol('x')
n = Symbol('n')
g = real_root(x, n)
assert g.subs(dict(x=-8, n=3)) == -2
assert g.subs(dict(x=8, n=3)) == 2
# give principle root if there is no real root -- if this is not desired
# then maybe a Root class is needed to raise an error instead
assert g.subs(dict(x=I, n=3)) == cbrt(I)
assert g.subs(dict(x=-8, n=2)) == sqrt(-8)
assert g.subs(dict(x=I, n=2)) == sqrt(I)
def test_issue_11463():
numpy = import_module('numpy')
if not numpy:
skip("numpy not installed.")
x = Symbol('x')
f = lambdify(x, real_root((log(x/(x-2))), 3), 'numpy')
# numpy.select evaluates all options before considering conditions,
# so it raises a warning about root of negative number which does
# not affect the outcome. This warning is suppressed here
with ignore_warnings(RuntimeWarning):
assert f(numpy.array(-1)) < -1
def test_rewrite_MaxMin_as_Heaviside():
from sympy.abc import x
assert Max(0, x).rewrite(Heaviside) == x*Heaviside(x)
assert Max(3, x).rewrite(Heaviside) == x*Heaviside(x - 3) + \
3*Heaviside(-x + 3)
assert Max(0, x+2, 2*x).rewrite(Heaviside) == \
2*x*Heaviside(2*x)*Heaviside(x - 2) + \
(x + 2)*Heaviside(-x + 2)*Heaviside(x + 2)
assert Min(0, x).rewrite(Heaviside) == x*Heaviside(-x)
assert Min(3, x).rewrite(Heaviside) == x*Heaviside(-x + 3) + \
3*Heaviside(x - 3)
assert Min(x, -x, -2).rewrite(Heaviside) == \
x*Heaviside(-2*x)*Heaviside(-x - 2) - \
x*Heaviside(2*x)*Heaviside(x - 2) \
- 2*Heaviside(-x + 2)*Heaviside(x + 2)
def test_rewrite_MaxMin_as_Piecewise():
from sympy import symbols, Piecewise
x, y, z, a, b = symbols('x y z a b', real=True)
vx, vy, va = symbols('vx vy va')
assert Max(a, b).rewrite(Piecewise) == Piecewise((a, a >= b), (b, True))
assert Max(x, y, z).rewrite(Piecewise) == Piecewise((x, (x >= y) & (x >= z)), (y, y >= z), (z, True))
assert Max(x, y, a, b).rewrite(Piecewise) == Piecewise((a, (a >= b) & (a >= x) & (a >= y)),
(b, (b >= x) & (b >= y)), (x, x >= y), (y, True))
assert Min(a, b).rewrite(Piecewise) == Piecewise((a, a <= b), (b, True))
assert Min(x, y, z).rewrite(Piecewise) == Piecewise((x, (x <= y) & (x <= z)), (y, y <= z), (z, True))
assert Min(x, y, a, b).rewrite(Piecewise) == Piecewise((a, (a <= b) & (a <= x) & (a <= y)),
(b, (b <= x) & (b <= y)), (x, x <= y), (y, True))
# Piecewise rewriting of Min/Max does also takes place for not explicitly real arguments
assert Max(vx, vy).rewrite(Piecewise) == Piecewise((vx, vx >= vy), (vy, True))
assert Min(va, vx, vy).rewrite(Piecewise) == Piecewise((va, (va <= vx) & (va <= vy)), (vx, vx <= vy), (vy, True))
def test_issue_11099():
from sympy.abc import x, y
# some fixed value tests
fixed_test_data = {x: -2, y: 3}
assert Min(x, y).evalf(subs=fixed_test_data) == \
Min(x, y).subs(fixed_test_data).evalf()
assert Max(x, y).evalf(subs=fixed_test_data) == \
Max(x, y).subs(fixed_test_data).evalf()
# randomly generate some test data
from random import randint
for i in range(20):
random_test_data = {x: randint(-100, 100), y: randint(-100, 100)}
assert Min(x, y).evalf(subs=random_test_data) == \
Min(x, y).subs(random_test_data).evalf()
assert Max(x, y).evalf(subs=random_test_data) == \
Max(x, y).subs(random_test_data).evalf()
def test_issue_12638():
from sympy.abc import a, b, c
assert Min(a, b, c, Max(a, b)) == Min(a, b, c)
assert Min(a, b, Max(a, b, c)) == Min(a, b)
assert Min(a, b, Max(a, c)) == Min(a, b)
def test_issue_21399():
from sympy.abc import a, b, c
assert Max(Min(a, b), Min(a, b, c)) == Min(a, b)
def test_instantiation_evaluation():
from sympy.abc import v, w, x, y, z
assert Min(1, Max(2, x)) == 1
assert Max(3, Min(2, x)) == 3
assert Min(Max(x, y), Max(x, z)) == Max(x, Min(y, z))
assert set(Min(Max(w, x), Max(y, z)).args) == {
Max(w, x), Max(y, z)}
assert Min(Max(x, y), Max(x, z), w) == Min(
w, Max(x, Min(y, z)))
A, B = Min, Max
for i in range(2):
assert A(x, B(x, y)) == x
assert A(x, B(y, A(x, w, z))) == A(x, B(y, A(w, z)))
A, B = B, A
assert Min(w, Max(x, y), Max(v, x, z)) == Min(
w, Max(x, Min(y, Max(v, z))))
def test_rewrite_as_Abs():
from itertools import permutations
from sympy.functions.elementary.complexes import Abs
from sympy.abc import x, y, z, w
def test(e):
free = e.free_symbols
a = e.rewrite(Abs)
assert not a.has(Min, Max)
for i in permutations(range(len(free))):
reps = dict(zip(free, i))
assert a.xreplace(reps) == e.xreplace(reps)
test(Min(x, y))
test(Max(x, y))
test(Min(x, y, z))
test(Min(Max(w, x), Max(y, z)))
def test_issue_14000():
assert isinstance(sqrt(4, evaluate=False), Pow) == True
assert isinstance(cbrt(3.5, evaluate=False), Pow) == True
assert isinstance(root(16, 4, evaluate=False), Pow) == True
assert sqrt(4, evaluate=False) == Pow(4, S.Half, evaluate=False)
assert cbrt(3.5, evaluate=False) == Pow(3.5, Rational(1, 3), evaluate=False)
assert root(4, 2, evaluate=False) == Pow(4, S.Half, evaluate=False)
assert root(16, 4, 2, evaluate=False).has(Pow) == True
assert real_root(-8, 3, evaluate=False).has(Pow) == True
def test_issue_6899():
from sympy import Lambda
x = Symbol('x')
eqn = Lambda(x, x)
assert eqn.func(*eqn.args) == eqn
|
ec7926ac99c28c07cee2b603d438add1da5f59a784ab143d1e4877e28bfaf2c8 | from sympy import (Symbol, zeta, nan, Rational, Float, pi, dirichlet_eta, log,
zoo, expand_func, polylog, lerchphi, S, exp, sqrt, I,
exp_polar, polar_lift, O, stieltjes, Abs, Sum, oo, riemann_xi)
from sympy.core.function import ArgumentIndexError
from sympy.functions.combinatorial.numbers import bernoulli, factorial
from sympy.testing.pytest import raises
from sympy.testing.randtest import (test_derivative_numerically as td,
random_complex_number as randcplx, verify_numerically as tn)
x = Symbol('x')
a = Symbol('a')
b = Symbol('b', negative=True)
z = Symbol('z')
s = Symbol('s')
def test_zeta_eval():
assert zeta(nan) is nan
assert zeta(x, nan) is nan
assert zeta(0) == Rational(-1, 2)
assert zeta(0, x) == S.Half - x
assert zeta(0, b) == S.Half - b
assert zeta(1) is zoo
assert zeta(1, 2) is zoo
assert zeta(1, -7) is zoo
assert zeta(1, x) is zoo
assert zeta(2, 1) == pi**2/6
assert zeta(2) == pi**2/6
assert zeta(4) == pi**4/90
assert zeta(6) == pi**6/945
assert zeta(2, 2) == pi**2/6 - 1
assert zeta(4, 3) == pi**4/90 - Rational(17, 16)
assert zeta(6, 4) == pi**6/945 - Rational(47449, 46656)
assert zeta(2, -2) == pi**2/6 + Rational(5, 4)
assert zeta(4, -3) == pi**4/90 + Rational(1393, 1296)
assert zeta(6, -4) == pi**6/945 + Rational(3037465, 2985984)
assert zeta(oo) == 1
assert zeta(-1) == Rational(-1, 12)
assert zeta(-2) == 0
assert zeta(-3) == Rational(1, 120)
assert zeta(-4) == 0
assert zeta(-5) == Rational(-1, 252)
assert zeta(-1, 3) == Rational(-37, 12)
assert zeta(-1, 7) == Rational(-253, 12)
assert zeta(-1, -4) == Rational(119, 12)
assert zeta(-1, -9) == Rational(539, 12)
assert zeta(-4, 3) == -17
assert zeta(-4, -8) == 8772
assert zeta(0, 1) == Rational(-1, 2)
assert zeta(0, -1) == Rational(3, 2)
assert zeta(0, 2) == Rational(-3, 2)
assert zeta(0, -2) == Rational(5, 2)
assert zeta(
3).evalf(20).epsilon_eq(Float("1.2020569031595942854", 20), 1e-19)
def test_zeta_series():
assert zeta(x, a).series(a, 0, 2) == \
zeta(x, 0) - x*a*zeta(x + 1, 0) + O(a**2)
def test_dirichlet_eta_eval():
assert dirichlet_eta(0) == S.Half
assert dirichlet_eta(-1) == Rational(1, 4)
assert dirichlet_eta(1) == log(2)
assert dirichlet_eta(2) == pi**2/12
assert dirichlet_eta(4) == pi**4*Rational(7, 720)
def test_riemann_xi_eval():
assert riemann_xi(2) == pi/6
assert riemann_xi(0) == Rational(1, 2)
assert riemann_xi(1) == Rational(1, 2)
assert riemann_xi(3).rewrite(zeta) == 3*zeta(3)/(2*pi)
assert riemann_xi(4) == pi**2/15
def test_rewriting():
assert dirichlet_eta(x).rewrite(zeta) == (1 - 2**(1 - x))*zeta(x)
assert zeta(x).rewrite(dirichlet_eta) == dirichlet_eta(x)/(1 - 2**(1 - x))
assert zeta(x).rewrite(dirichlet_eta, a=2) == zeta(x)
assert tn(dirichlet_eta(x), dirichlet_eta(x).rewrite(zeta), x)
assert tn(zeta(x), zeta(x).rewrite(dirichlet_eta), x)
assert zeta(x, a).rewrite(lerchphi) == lerchphi(1, x, a)
assert polylog(s, z).rewrite(lerchphi) == lerchphi(z, s, 1)*z
assert lerchphi(1, x, a).rewrite(zeta) == zeta(x, a)
assert z*lerchphi(z, s, 1).rewrite(polylog) == polylog(s, z)
def test_derivatives():
from sympy import Derivative
assert zeta(x, a).diff(x) == Derivative(zeta(x, a), x)
assert zeta(x, a).diff(a) == -x*zeta(x + 1, a)
assert lerchphi(
z, s, a).diff(z) == (lerchphi(z, s - 1, a) - a*lerchphi(z, s, a))/z
assert lerchphi(z, s, a).diff(a) == -s*lerchphi(z, s + 1, a)
assert polylog(s, z).diff(z) == polylog(s - 1, z)/z
b = randcplx()
c = randcplx()
assert td(zeta(b, x), x)
assert td(polylog(b, z), z)
assert td(lerchphi(c, b, x), x)
assert td(lerchphi(x, b, c), x)
raises(ArgumentIndexError, lambda: lerchphi(c, b, x).fdiff(2))
raises(ArgumentIndexError, lambda: lerchphi(c, b, x).fdiff(4))
raises(ArgumentIndexError, lambda: polylog(b, z).fdiff(1))
raises(ArgumentIndexError, lambda: polylog(b, z).fdiff(3))
def myexpand(func, target):
expanded = expand_func(func)
if target is not None:
return expanded == target
if expanded == func: # it didn't expand
return False
# check to see that the expanded and original evaluate to the same value
subs = {}
for a in func.free_symbols:
subs[a] = randcplx()
return abs(func.subs(subs).n()
- expanded.replace(exp_polar, exp).subs(subs).n()) < 1e-10
def test_polylog_expansion():
from sympy import log
assert polylog(s, 0) == 0
assert polylog(s, 1) == zeta(s)
assert polylog(s, -1) == -dirichlet_eta(s)
assert polylog(s, exp_polar(I*pi*Rational(4, 3))) == polylog(s, exp(I*pi*Rational(4, 3)))
assert polylog(s, exp_polar(I*pi)/3) == polylog(s, exp(I*pi)/3)
assert myexpand(polylog(1, z), -log(1 - z))
assert myexpand(polylog(0, z), z/(1 - z))
assert myexpand(polylog(-1, z), z/(1 - z)**2)
assert ((1-z)**3 * expand_func(polylog(-2, z))).simplify() == z*(1 + z)
assert myexpand(polylog(-5, z), None)
def test_polylog_series():
assert polylog(1, z).series(z, n=5) == z + z**2/2 + z**3/3 + z**4/4 + O(z**5)
assert polylog(1, sqrt(z)).series(z, n=3) == z/2 + z**2/4 + sqrt(z)\
+ z**(S(3)/2)/3 + z**(S(5)/2)/5 + O(z**3)
# https://github.com/sympy/sympy/issues/9497
assert polylog(S(3)/2, -z).series(z, 0, 5) == -z + sqrt(2)*z**2/4\
- sqrt(3)*z**3/9 + z**4/8 + O(z**5)
def test_issue_8404():
i = Symbol('i', integer=True)
assert Abs(Sum(1/(3*i + 1)**2, (i, 0, S.Infinity)).doit().n(4)
- 1.122) < 0.001
def test_polylog_values():
from sympy.testing.randtest import verify_numerically as tn
assert polylog(2, 2) == pi**2/4 - I*pi*log(2)
assert polylog(2, S.Half) == pi**2/12 - log(2)**2/2
for z in [S.Half, 2, (sqrt(5)-1)/2, -(sqrt(5)-1)/2, -(sqrt(5)+1)/2, (3-sqrt(5))/2]:
assert Abs(polylog(2, z).evalf() - polylog(2, z, evaluate=False).evalf()) < 1e-15
z = Symbol("z")
for s in [-1, 0]:
for _ in range(10):
assert tn(polylog(s, z), polylog(s, z, evaluate=False), z,
a=-3, b=-2, c=S.Half, d=2)
assert tn(polylog(s, z), polylog(s, z, evaluate=False), z,
a=2, b=-2, c=5, d=2)
from sympy import Integral
assert polylog(0, Integral(1, (x, 0, 1))) == -S.Half
def test_lerchphi_expansion():
assert myexpand(lerchphi(1, s, a), zeta(s, a))
assert myexpand(lerchphi(z, s, 1), polylog(s, z)/z)
# direct summation
assert myexpand(lerchphi(z, -1, a), a/(1 - z) + z/(1 - z)**2)
assert myexpand(lerchphi(z, -3, a), None)
# polylog reduction
assert myexpand(lerchphi(z, s, S.Half),
2**(s - 1)*(polylog(s, sqrt(z))/sqrt(z)
- polylog(s, polar_lift(-1)*sqrt(z))/sqrt(z)))
assert myexpand(lerchphi(z, s, 2), -1/z + polylog(s, z)/z**2)
assert myexpand(lerchphi(z, s, Rational(3, 2)), None)
assert myexpand(lerchphi(z, s, Rational(7, 3)), None)
assert myexpand(lerchphi(z, s, Rational(-1, 3)), None)
assert myexpand(lerchphi(z, s, Rational(-5, 2)), None)
# hurwitz zeta reduction
assert myexpand(lerchphi(-1, s, a),
2**(-s)*zeta(s, a/2) - 2**(-s)*zeta(s, (a + 1)/2))
assert myexpand(lerchphi(I, s, a), None)
assert myexpand(lerchphi(-I, s, a), None)
assert myexpand(lerchphi(exp(I*pi*Rational(2, 5)), s, a), None)
def test_stieltjes():
assert isinstance(stieltjes(x), stieltjes)
assert isinstance(stieltjes(x, a), stieltjes)
# Zero'th constant EulerGamma
assert stieltjes(0) == S.EulerGamma
assert stieltjes(0, 1) == S.EulerGamma
# Not defined
assert stieltjes(nan) is nan
assert stieltjes(0, nan) is nan
assert stieltjes(-1) is S.ComplexInfinity
assert stieltjes(1.5) is S.ComplexInfinity
assert stieltjes(z, 0) is S.ComplexInfinity
assert stieltjes(z, -1) is S.ComplexInfinity
def test_stieltjes_evalf():
assert abs(stieltjes(0).evalf() - 0.577215664) < 1E-9
assert abs(stieltjes(0, 0.5).evalf() - 1.963510026) < 1E-9
assert abs(stieltjes(1, 2).evalf() + 0.072815845 ) < 1E-9
def test_issue_10475():
a = Symbol('a', extended_real=True)
b = Symbol('b', extended_positive=True)
s = Symbol('s', zero=False)
assert zeta(2 + I).is_finite
assert zeta(1).is_finite is False
assert zeta(x).is_finite is None
assert zeta(x + I).is_finite is None
assert zeta(a).is_finite is None
assert zeta(b).is_finite is None
assert zeta(-b).is_finite is True
assert zeta(b**2 - 2*b + 1).is_finite is None
assert zeta(a + I).is_finite is True
assert zeta(b + 1).is_finite is True
assert zeta(s + 1).is_finite is True
def test_issue_14177():
n = Symbol('n', positive=True, integer=True)
assert zeta(2*n) == (-1)**(n + 1)*2**(2*n - 1)*pi**(2*n)*bernoulli(2*n)/factorial(2*n)
assert zeta(-n) == (-1)**(-n)*bernoulli(n + 1)/(n + 1)
n = Symbol('n')
assert zeta(2*n) == zeta(2*n) # As sign of z (= 2*n) is not determined
|
66ff6d6af774d3eaf58d82e5609adce39500a1e3db48f774c3df25b504f4ad0a | from itertools import product
from sympy import (jn, yn, symbols, Symbol, sin, cos, pi, S, jn_zeros, besselj,
bessely, besseli, besselk, hankel1, hankel2, hn1, hn2,
expand_func, sqrt, sinh, cosh, diff, series, gamma, hyper,
I, O, oo, conjugate, uppergamma, exp, Integral, Sum,
Rational, log, polar_lift, exp_polar)
from sympy.functions.special.bessel import fn
from sympy.functions.special.bessel import (airyai, airybi,
airyaiprime, airybiprime, marcumq)
from sympy.testing.randtest import (random_complex_number as randcplx,
verify_numerically as tn,
test_derivative_numerically as td,
_randint)
from sympy.simplify import besselsimp
from sympy.testing.pytest import raises, slow
from sympy.abc import z, n, k, x
randint = _randint()
def test_bessel_rand():
for f in [besselj, bessely, besseli, besselk, hankel1, hankel2]:
assert td(f(randcplx(), z), z)
for f in [jn, yn, hn1, hn2]:
assert td(f(randint(-10, 10), z), z)
def test_bessel_twoinputs():
for f in [besselj, bessely, besseli, besselk, hankel1, hankel2, jn, yn]:
raises(TypeError, lambda: f(1))
raises(TypeError, lambda: f(1, 2, 3))
def test_besselj_leading_term():
assert besselj(0, x).as_leading_term(x) == 1
assert besselj(1, sin(x)).as_leading_term(x) == x/2
assert besselj(1, 2*sqrt(x)).as_leading_term(x) == sqrt(x)
# https://github.com/sympy/sympy/issues/21701
assert (besselj(z, x)/x**z).as_leading_term(x) == 1/(2**z*gamma(z + 1))
def test_bessely_leading_term():
assert bessely(0, x).as_leading_term(x) == (2*log(x) - 2*log(2))/pi
assert bessely(1, sin(x)).as_leading_term(x) == (x*log(x) - x*log(2))/pi
assert bessely(1, 2*sqrt(x)).as_leading_term(x) == sqrt(x)*log(x)/pi
def test_besselj_series():
assert besselj(0, x).series(x) == 1 - x**2/4 + x**4/64 + O(x**6)
assert besselj(0, x**(1.1)).series(x) == 1 + x**4.4/64 - x**2.2/4 + O(x**6)
assert besselj(0, x**2 + x).series(x) == 1 - x**2/4 - x**3/2\
- 15*x**4/64 + x**5/16 + O(x**6)
assert besselj(0, sqrt(x) + x).series(x, n=4) == 1 - x/4 - 15*x**2/64\
+ 215*x**3/2304 - x**Rational(3, 2)/2 + x**Rational(5, 2)/16\
+ 23*x**Rational(7, 2)/384 + O(x**4)
assert besselj(0, x/(1 - x)).series(x) == 1 - x**2/4 - x**3/2 - 47*x**4/64\
- 15*x**5/16 + O(x**6)
assert besselj(0, log(1 + x)).series(x) == 1 - x**2/4 + x**3/4\
- 41*x**4/192 + 17*x**5/96 + O(x**6)
assert besselj(1, sin(x)).series(x) == x/2 - 7*x**3/48 + 73*x**5/1920 + O(x**6)
assert besselj(1, 2*sqrt(x)).series(x) == sqrt(x) - x**Rational(3, 2)/2\
+ x**Rational(5, 2)/12 - x**Rational(7, 2)/144 + x**Rational(9, 2)/2880\
- x**Rational(11, 2)/86400 + O(x**6)
assert besselj(-2, sin(x)).series(x, n=4) == besselj(2, sin(x)).series(x, n=4)
def test_bessely_series():
const = 2*S.EulerGamma/pi - 2*log(2)/pi + 2*log(x)/pi
assert bessely(0, x).series(x, n=4) == const + x**2*(-log(x)/(2*pi)\
+ (2 - 2*S.EulerGamma)/(4*pi) + log(2)/(2*pi)) + O(x**4*log(x))
assert bessely(0, x**(1.1)).series(x, n=4) == 2*S.EulerGamma/pi\
- 2*log(2)/pi + 2.2*log(x)/pi + x**2.2*(-0.55*log(x)/pi\
+ (2 - 2*S.EulerGamma)/(4*pi) + log(2)/(2*pi)) + O(x**4*log(x))
assert bessely(0, x**2 + x).series(x, n=4) == \
const - (2 - 2*S.EulerGamma)*(-x**3/(2*pi) - x**2/(4*pi)) + 2*x/pi\
+ x**2*(-log(x)/(2*pi) - 1/pi + log(2)/(2*pi))\
+ x**3*(-log(x)/pi + 1/(6*pi) + log(2)/pi) + O(x**4*log(x))
assert bessely(0, x/(1 - x)).series(x, n=3) == const\
+ 2*x/pi + x**2*(-log(x)/(2*pi) + (2 - 2*S.EulerGamma)/(4*pi)\
+ log(2)/(2*pi) + 1/pi) + O(x**3*log(x))
assert bessely(0, log(1 + x)).series(x, n=3) == const\
- x/pi + x**2*(-log(x)/(2*pi) + (2 - 2*S.EulerGamma)/(4*pi)\
+ log(2)/(2*pi) + 5/(12*pi)) + O(x**3*log(x))
assert bessely(1, sin(x)).series(x, n=4) == -(1/pi)*(1 - 2*S.EulerGamma)\
* (-x**3/12 + x/2) + x*(log(x)/pi - log(2)/pi) + x**3*(-7*log(x)\
/ (24*pi) - 1/(6*pi) + (Rational(5, 2) - 2*S.EulerGamma)/(16*pi)\
+ 7*log(2)/(24*pi)) + O(x**4*log(x))
assert bessely(1, 2*sqrt(x)).series(x, n=3) == sqrt(x)*(log(x)/pi \
- (1 - 2*S.EulerGamma)/pi) + x**Rational(3, 2)*(-log(x)/(2*pi)\
+ (Rational(5, 2) - 2*S.EulerGamma)/(2*pi))\
+ x**Rational(5, 2)*(log(x)/(12*pi)\
- (Rational(10, 3) - 2*S.EulerGamma)/(12*pi)) + O(x**3*log(x))
assert bessely(-2, sin(x)).series(x, n=4) == bessely(2, sin(x)).series(x, n=4)
def test_diff():
assert besselj(n, z).diff(z) == besselj(n - 1, z)/2 - besselj(n + 1, z)/2
assert bessely(n, z).diff(z) == bessely(n - 1, z)/2 - bessely(n + 1, z)/2
assert besseli(n, z).diff(z) == besseli(n - 1, z)/2 + besseli(n + 1, z)/2
assert besselk(n, z).diff(z) == -besselk(n - 1, z)/2 - besselk(n + 1, z)/2
assert hankel1(n, z).diff(z) == hankel1(n - 1, z)/2 - hankel1(n + 1, z)/2
assert hankel2(n, z).diff(z) == hankel2(n - 1, z)/2 - hankel2(n + 1, z)/2
def test_rewrite():
assert besselj(n, z).rewrite(jn) == sqrt(2*z/pi)*jn(n - S.Half, z)
assert bessely(n, z).rewrite(yn) == sqrt(2*z/pi)*yn(n - S.Half, z)
assert besseli(n, z).rewrite(besselj) == \
exp(-I*n*pi/2)*besselj(n, polar_lift(I)*z)
assert besselj(n, z).rewrite(besseli) == \
exp(I*n*pi/2)*besseli(n, polar_lift(-I)*z)
nu = randcplx()
assert tn(besselj(nu, z), besselj(nu, z).rewrite(besseli), z)
assert tn(besselj(nu, z), besselj(nu, z).rewrite(bessely), z)
assert tn(besseli(nu, z), besseli(nu, z).rewrite(besselj), z)
assert tn(besseli(nu, z), besseli(nu, z).rewrite(bessely), z)
assert tn(bessely(nu, z), bessely(nu, z).rewrite(besselj), z)
assert tn(bessely(nu, z), bessely(nu, z).rewrite(besseli), z)
assert tn(besselk(nu, z), besselk(nu, z).rewrite(besselj), z)
assert tn(besselk(nu, z), besselk(nu, z).rewrite(besseli), z)
assert tn(besselk(nu, z), besselk(nu, z).rewrite(bessely), z)
# check that a rewrite was triggered, when the order is set to a generic
# symbol 'nu'
assert yn(nu, z) != yn(nu, z).rewrite(jn)
assert hn1(nu, z) != hn1(nu, z).rewrite(jn)
assert hn2(nu, z) != hn2(nu, z).rewrite(jn)
assert jn(nu, z) != jn(nu, z).rewrite(yn)
assert hn1(nu, z) != hn1(nu, z).rewrite(yn)
assert hn2(nu, z) != hn2(nu, z).rewrite(yn)
# rewriting spherical bessel functions (SBFs) w.r.t. besselj, bessely is
# not allowed if a generic symbol 'nu' is used as the order of the SBFs
# to avoid inconsistencies (the order of bessel[jy] is allowed to be
# complex-valued, whereas SBFs are defined only for integer orders)
order = nu
for f in (besselj, bessely):
assert hn1(order, z) == hn1(order, z).rewrite(f)
assert hn2(order, z) == hn2(order, z).rewrite(f)
assert jn(order, z).rewrite(besselj) == sqrt(2)*sqrt(pi)*sqrt(1/z)*besselj(order + S.Half, z)/2
assert jn(order, z).rewrite(bessely) == (-1)**nu*sqrt(2)*sqrt(pi)*sqrt(1/z)*bessely(-order - S.Half, z)/2
# for integral orders rewriting SBFs w.r.t bessel[jy] is allowed
N = Symbol('n', integer=True)
ri = randint(-11, 10)
for order in (ri, N):
for f in (besselj, bessely):
assert yn(order, z) != yn(order, z).rewrite(f)
assert jn(order, z) != jn(order, z).rewrite(f)
assert hn1(order, z) != hn1(order, z).rewrite(f)
assert hn2(order, z) != hn2(order, z).rewrite(f)
for func, refunc in product((yn, jn, hn1, hn2),
(jn, yn, besselj, bessely)):
assert tn(func(ri, z), func(ri, z).rewrite(refunc), z)
def test_expand():
assert expand_func(besselj(S.Half, z).rewrite(jn)) == \
sqrt(2)*sin(z)/(sqrt(pi)*sqrt(z))
assert expand_func(bessely(S.Half, z).rewrite(yn)) == \
-sqrt(2)*cos(z)/(sqrt(pi)*sqrt(z))
# XXX: teach sin/cos to work around arguments like
# x*exp_polar(I*pi*n/2). Then change besselsimp -> expand_func
assert besselsimp(besselj(S.Half, z)) == sqrt(2)*sin(z)/(sqrt(pi)*sqrt(z))
assert besselsimp(besselj(Rational(-1, 2), z)) == sqrt(2)*cos(z)/(sqrt(pi)*sqrt(z))
assert besselsimp(besselj(Rational(5, 2), z)) == \
-sqrt(2)*(z**2*sin(z) + 3*z*cos(z) - 3*sin(z))/(sqrt(pi)*z**Rational(5, 2))
assert besselsimp(besselj(Rational(-5, 2), z)) == \
-sqrt(2)*(z**2*cos(z) - 3*z*sin(z) - 3*cos(z))/(sqrt(pi)*z**Rational(5, 2))
assert besselsimp(bessely(S.Half, z)) == \
-(sqrt(2)*cos(z))/(sqrt(pi)*sqrt(z))
assert besselsimp(bessely(Rational(-1, 2), z)) == sqrt(2)*sin(z)/(sqrt(pi)*sqrt(z))
assert besselsimp(bessely(Rational(5, 2), z)) == \
sqrt(2)*(z**2*cos(z) - 3*z*sin(z) - 3*cos(z))/(sqrt(pi)*z**Rational(5, 2))
assert besselsimp(bessely(Rational(-5, 2), z)) == \
-sqrt(2)*(z**2*sin(z) + 3*z*cos(z) - 3*sin(z))/(sqrt(pi)*z**Rational(5, 2))
assert besselsimp(besseli(S.Half, z)) == sqrt(2)*sinh(z)/(sqrt(pi)*sqrt(z))
assert besselsimp(besseli(Rational(-1, 2), z)) == \
sqrt(2)*cosh(z)/(sqrt(pi)*sqrt(z))
assert besselsimp(besseli(Rational(5, 2), z)) == \
sqrt(2)*(z**2*sinh(z) - 3*z*cosh(z) + 3*sinh(z))/(sqrt(pi)*z**Rational(5, 2))
assert besselsimp(besseli(Rational(-5, 2), z)) == \
sqrt(2)*(z**2*cosh(z) - 3*z*sinh(z) + 3*cosh(z))/(sqrt(pi)*z**Rational(5, 2))
assert besselsimp(besselk(S.Half, z)) == \
besselsimp(besselk(Rational(-1, 2), z)) == sqrt(pi)*exp(-z)/(sqrt(2)*sqrt(z))
assert besselsimp(besselk(Rational(5, 2), z)) == \
besselsimp(besselk(Rational(-5, 2), z)) == \
sqrt(2)*sqrt(pi)*(z**2 + 3*z + 3)*exp(-z)/(2*z**Rational(5, 2))
n = Symbol('n', integer=True, positive=True)
assert expand_func(besseli(n + 2, z)) == \
besseli(n, z) + (-2*n - 2)*(-2*n*besseli(n, z)/z + besseli(n - 1, z))/z
assert expand_func(besselj(n + 2, z)) == \
-besselj(n, z) + (2*n + 2)*(2*n*besselj(n, z)/z - besselj(n - 1, z))/z
assert expand_func(besselk(n + 2, z)) == \
besselk(n, z) + (2*n + 2)*(2*n*besselk(n, z)/z + besselk(n - 1, z))/z
assert expand_func(bessely(n + 2, z)) == \
-bessely(n, z) + (2*n + 2)*(2*n*bessely(n, z)/z - bessely(n - 1, z))/z
assert expand_func(besseli(n + S.Half, z).rewrite(jn)) == \
(sqrt(2)*sqrt(z)*exp(-I*pi*(n + S.Half)/2) *
exp_polar(I*pi/4)*jn(n, z*exp_polar(I*pi/2))/sqrt(pi))
assert expand_func(besselj(n + S.Half, z).rewrite(jn)) == \
sqrt(2)*sqrt(z)*jn(n, z)/sqrt(pi)
r = Symbol('r', real=True)
p = Symbol('p', positive=True)
i = Symbol('i', integer=True)
for besselx in [besselj, bessely, besseli, besselk]:
assert besselx(i, p).is_extended_real is True
assert besselx(i, x).is_extended_real is None
assert besselx(x, z).is_extended_real is None
for besselx in [besselj, besseli]:
assert besselx(i, r).is_extended_real is True
for besselx in [bessely, besselk]:
assert besselx(i, r).is_extended_real is None
for besselx in [besselj, bessely, besseli, besselk]:
assert expand_func(besselx(oo, x)) == besselx(oo, x, evaluate=False)
assert expand_func(besselx(-oo, x)) == besselx(-oo, x, evaluate=False)
@slow
def test_slow_expand():
def check(eq, ans):
return tn(eq, ans) and eq == ans
rn = randcplx(a=1, b=0, d=0, c=2)
for besselx in [besselj, bessely, besseli, besselk]:
ri = S(2*randint(-11, 10) + 1) / 2 # half integer in [-21/2, 21/2]
assert tn(besselsimp(besselx(ri, z)), besselx(ri, z))
assert check(expand_func(besseli(rn, x)),
besseli(rn - 2, x) - 2*(rn - 1)*besseli(rn - 1, x)/x)
assert check(expand_func(besseli(-rn, x)),
besseli(-rn + 2, x) + 2*(-rn + 1)*besseli(-rn + 1, x)/x)
assert check(expand_func(besselj(rn, x)),
-besselj(rn - 2, x) + 2*(rn - 1)*besselj(rn - 1, x)/x)
assert check(expand_func(besselj(-rn, x)),
-besselj(-rn + 2, x) + 2*(-rn + 1)*besselj(-rn + 1, x)/x)
assert check(expand_func(besselk(rn, x)),
besselk(rn - 2, x) + 2*(rn - 1)*besselk(rn - 1, x)/x)
assert check(expand_func(besselk(-rn, x)),
besselk(-rn + 2, x) - 2*(-rn + 1)*besselk(-rn + 1, x)/x)
assert check(expand_func(bessely(rn, x)),
-bessely(rn - 2, x) + 2*(rn - 1)*bessely(rn - 1, x)/x)
assert check(expand_func(bessely(-rn, x)),
-bessely(-rn + 2, x) + 2*(-rn + 1)*bessely(-rn + 1, x)/x)
def test_fn():
x, z = symbols("x z")
assert fn(1, z) == 1/z**2
assert fn(2, z) == -1/z + 3/z**3
assert fn(3, z) == -6/z**2 + 15/z**4
assert fn(4, z) == 1/z - 45/z**3 + 105/z**5
def mjn(n, z):
return expand_func(jn(n, z))
def myn(n, z):
return expand_func(yn(n, z))
def test_jn():
z = symbols("z")
assert jn(0, 0) == 1
assert jn(1, 0) == 0
assert jn(-1, 0) == S.ComplexInfinity
assert jn(z, 0) == jn(z, 0, evaluate=False)
assert jn(0, oo) == 0
assert jn(0, -oo) == 0
assert mjn(0, z) == sin(z)/z
assert mjn(1, z) == sin(z)/z**2 - cos(z)/z
assert mjn(2, z) == (3/z**3 - 1/z)*sin(z) - (3/z**2) * cos(z)
assert mjn(3, z) == (15/z**4 - 6/z**2)*sin(z) + (1/z - 15/z**3)*cos(z)
assert mjn(4, z) == (1/z + 105/z**5 - 45/z**3)*sin(z) + \
(-105/z**4 + 10/z**2)*cos(z)
assert mjn(5, z) == (945/z**6 - 420/z**4 + 15/z**2)*sin(z) + \
(-1/z - 945/z**5 + 105/z**3)*cos(z)
assert mjn(6, z) == (-1/z + 10395/z**7 - 4725/z**5 + 210/z**3)*sin(z) + \
(-10395/z**6 + 1260/z**4 - 21/z**2)*cos(z)
assert expand_func(jn(n, z)) == jn(n, z)
# SBFs not defined for complex-valued orders
assert jn(2+3j, 5.2+0.3j).evalf() == jn(2+3j, 5.2+0.3j)
assert eq([jn(2, 5.2+0.3j).evalf(10)],
[0.09941975672 - 0.05452508024*I])
def test_yn():
z = symbols("z")
assert myn(0, z) == -cos(z)/z
assert myn(1, z) == -cos(z)/z**2 - sin(z)/z
assert myn(2, z) == -((3/z**3 - 1/z)*cos(z) + (3/z**2)*sin(z))
assert expand_func(yn(n, z)) == yn(n, z)
# SBFs not defined for complex-valued orders
assert yn(2+3j, 5.2+0.3j).evalf() == yn(2+3j, 5.2+0.3j)
assert eq([yn(2, 5.2+0.3j).evalf(10)],
[0.185250342 + 0.01489557397*I])
def test_sympify_yn():
assert S(15) in myn(3, pi).atoms()
assert myn(3, pi) == 15/pi**4 - 6/pi**2
def eq(a, b, tol=1e-6):
for u, v in zip(a, b):
if not (abs(u - v) < tol):
return False
return True
def test_jn_zeros():
assert eq(jn_zeros(0, 4), [3.141592, 6.283185, 9.424777, 12.566370])
assert eq(jn_zeros(1, 4), [4.493409, 7.725251, 10.904121, 14.066193])
assert eq(jn_zeros(2, 4), [5.763459, 9.095011, 12.322940, 15.514603])
assert eq(jn_zeros(3, 4), [6.987932, 10.417118, 13.698023, 16.923621])
assert eq(jn_zeros(4, 4), [8.182561, 11.704907, 15.039664, 18.301255])
def test_bessel_eval():
n, m, k = Symbol('n', integer=True), Symbol('m'), Symbol('k', integer=True, zero=False)
for f in [besselj, besseli]:
assert f(0, 0) is S.One
assert f(2.1, 0) is S.Zero
assert f(-3, 0) is S.Zero
assert f(-10.2, 0) is S.ComplexInfinity
assert f(1 + 3*I, 0) is S.Zero
assert f(-3 + I, 0) is S.ComplexInfinity
assert f(-2*I, 0) is S.NaN
assert f(n, 0) != S.One and f(n, 0) != S.Zero
assert f(m, 0) != S.One and f(m, 0) != S.Zero
assert f(k, 0) is S.Zero
assert bessely(0, 0) is S.NegativeInfinity
assert besselk(0, 0) is S.Infinity
for f in [bessely, besselk]:
assert f(1 + I, 0) is S.ComplexInfinity
assert f(I, 0) is S.NaN
for f in [besselj, bessely]:
assert f(m, S.Infinity) is S.Zero
assert f(m, S.NegativeInfinity) is S.Zero
for f in [besseli, besselk]:
assert f(m, I*S.Infinity) is S.Zero
assert f(m, I*S.NegativeInfinity) is S.Zero
for f in [besseli, besselk]:
assert f(-4, z) == f(4, z)
assert f(-3, z) == f(3, z)
assert f(-n, z) == f(n, z)
assert f(-m, z) != f(m, z)
for f in [besselj, bessely]:
assert f(-4, z) == f(4, z)
assert f(-3, z) == -f(3, z)
assert f(-n, z) == (-1)**n*f(n, z)
assert f(-m, z) != (-1)**m*f(m, z)
for f in [besselj, besseli]:
assert f(m, -z) == (-z)**m*z**(-m)*f(m, z)
assert besseli(2, -z) == besseli(2, z)
assert besseli(3, -z) == -besseli(3, z)
assert besselj(0, -z) == besselj(0, z)
assert besselj(1, -z) == -besselj(1, z)
assert besseli(0, I*z) == besselj(0, z)
assert besseli(1, I*z) == I*besselj(1, z)
assert besselj(3, I*z) == -I*besseli(3, z)
def test_bessel_nan():
# FIXME: could have these return NaN; for now just fix infinite recursion
for f in [besselj, bessely, besseli, besselk, hankel1, hankel2, yn, jn]:
assert f(1, S.NaN) == f(1, S.NaN, evaluate=False)
def test_meromorphic():
assert besselj(2, x).is_meromorphic(x, 1) == True
assert besselj(2, x).is_meromorphic(x, 0) == True
assert besselj(2, x).is_meromorphic(x, oo) == False
assert besselj(S(2)/3, x).is_meromorphic(x, 1) == True
assert besselj(S(2)/3, x).is_meromorphic(x, 0) == False
assert besselj(S(2)/3, x).is_meromorphic(x, oo) == False
assert besselj(x, 2*x).is_meromorphic(x, 2) == False
assert besselk(0, x).is_meromorphic(x, 1) == True
assert besselk(2, x).is_meromorphic(x, 0) == True
assert besseli(0, x).is_meromorphic(x, 1) == True
assert besseli(2, x).is_meromorphic(x, 0) == True
assert bessely(0, x).is_meromorphic(x, 1) == True
assert bessely(0, x).is_meromorphic(x, 0) == False
assert bessely(2, x).is_meromorphic(x, 0) == True
assert hankel1(3, x**2 + 2*x).is_meromorphic(x, 1) == True
assert hankel1(0, x).is_meromorphic(x, 0) == False
assert hankel2(11, 4).is_meromorphic(x, 5) == True
assert hn1(6, 7*x**3 + 4).is_meromorphic(x, 7) == True
assert hn2(3, 2*x).is_meromorphic(x, 9) == True
assert jn(5, 2*x + 7).is_meromorphic(x, 4) == True
assert yn(8, x**2 + 11).is_meromorphic(x, 6) == True
def test_conjugate():
n = Symbol('n')
z = Symbol('z', extended_real=False)
x = Symbol('x', extended_real=True)
y = Symbol('y', real=True, positive=True)
t = Symbol('t', negative=True)
for f in [besseli, besselj, besselk, bessely, hankel1, hankel2]:
assert f(n, -1).conjugate() != f(conjugate(n), -1)
assert f(n, x).conjugate() != f(conjugate(n), x)
assert f(n, t).conjugate() != f(conjugate(n), t)
rz = randcplx(b=0.5)
for f in [besseli, besselj, besselk, bessely]:
assert f(n, 1 + I).conjugate() == f(conjugate(n), 1 - I)
assert f(n, 0).conjugate() == f(conjugate(n), 0)
assert f(n, 1).conjugate() == f(conjugate(n), 1)
assert f(n, z).conjugate() == f(conjugate(n), conjugate(z))
assert f(n, y).conjugate() == f(conjugate(n), y)
assert tn(f(n, rz).conjugate(), f(conjugate(n), conjugate(rz)))
assert hankel1(n, 1 + I).conjugate() == hankel2(conjugate(n), 1 - I)
assert hankel1(n, 0).conjugate() == hankel2(conjugate(n), 0)
assert hankel1(n, 1).conjugate() == hankel2(conjugate(n), 1)
assert hankel1(n, y).conjugate() == hankel2(conjugate(n), y)
assert hankel1(n, z).conjugate() == hankel2(conjugate(n), conjugate(z))
assert tn(hankel1(n, rz).conjugate(), hankel2(conjugate(n), conjugate(rz)))
assert hankel2(n, 1 + I).conjugate() == hankel1(conjugate(n), 1 - I)
assert hankel2(n, 0).conjugate() == hankel1(conjugate(n), 0)
assert hankel2(n, 1).conjugate() == hankel1(conjugate(n), 1)
assert hankel2(n, y).conjugate() == hankel1(conjugate(n), y)
assert hankel2(n, z).conjugate() == hankel1(conjugate(n), conjugate(z))
assert tn(hankel2(n, rz).conjugate(), hankel1(conjugate(n), conjugate(rz)))
def test_branching():
assert besselj(polar_lift(k), x) == besselj(k, x)
assert besseli(polar_lift(k), x) == besseli(k, x)
n = Symbol('n', integer=True)
assert besselj(n, exp_polar(2*pi*I)*x) == besselj(n, x)
assert besselj(n, polar_lift(x)) == besselj(n, x)
assert besseli(n, exp_polar(2*pi*I)*x) == besseli(n, x)
assert besseli(n, polar_lift(x)) == besseli(n, x)
def tn(func, s):
from random import uniform
c = uniform(1, 5)
expr = func(s, c*exp_polar(I*pi)) - func(s, c*exp_polar(-I*pi))
eps = 1e-15
expr2 = func(s + eps, -c + eps*I) - func(s + eps, -c - eps*I)
return abs(expr.n() - expr2.n()).n() < 1e-10
nu = Symbol('nu')
assert besselj(nu, exp_polar(2*pi*I)*x) == exp(2*pi*I*nu)*besselj(nu, x)
assert besseli(nu, exp_polar(2*pi*I)*x) == exp(2*pi*I*nu)*besseli(nu, x)
assert tn(besselj, 2)
assert tn(besselj, pi)
assert tn(besselj, I)
assert tn(besseli, 2)
assert tn(besseli, pi)
assert tn(besseli, I)
def test_airy_base():
z = Symbol('z')
x = Symbol('x', real=True)
y = Symbol('y', real=True)
assert conjugate(airyai(z)) == airyai(conjugate(z))
assert airyai(x).is_extended_real
assert airyai(x+I*y).as_real_imag() == (
airyai(x - I*y)/2 + airyai(x + I*y)/2,
I*(airyai(x - I*y) - airyai(x + I*y))/2)
def test_airyai():
z = Symbol('z', real=False)
t = Symbol('t', negative=True)
p = Symbol('p', positive=True)
assert isinstance(airyai(z), airyai)
assert airyai(0) == 3**Rational(1, 3)/(3*gamma(Rational(2, 3)))
assert airyai(oo) == 0
assert airyai(-oo) == 0
assert diff(airyai(z), z) == airyaiprime(z)
assert series(airyai(z), z, 0, 3) == (
3**Rational(5, 6)*gamma(Rational(1, 3))/(6*pi) - 3**Rational(1, 6)*z*gamma(Rational(2, 3))/(2*pi) + O(z**3))
assert airyai(z).rewrite(hyper) == (
-3**Rational(2, 3)*z*hyper((), (Rational(4, 3),), z**3/9)/(3*gamma(Rational(1, 3))) +
3**Rational(1, 3)*hyper((), (Rational(2, 3),), z**3/9)/(3*gamma(Rational(2, 3))))
assert isinstance(airyai(z).rewrite(besselj), airyai)
assert airyai(t).rewrite(besselj) == (
sqrt(-t)*(besselj(Rational(-1, 3), 2*(-t)**Rational(3, 2)/3) +
besselj(Rational(1, 3), 2*(-t)**Rational(3, 2)/3))/3)
assert airyai(z).rewrite(besseli) == (
-z*besseli(Rational(1, 3), 2*z**Rational(3, 2)/3)/(3*(z**Rational(3, 2))**Rational(1, 3)) +
(z**Rational(3, 2))**Rational(1, 3)*besseli(Rational(-1, 3), 2*z**Rational(3, 2)/3)/3)
assert airyai(p).rewrite(besseli) == (
sqrt(p)*(besseli(Rational(-1, 3), 2*p**Rational(3, 2)/3) -
besseli(Rational(1, 3), 2*p**Rational(3, 2)/3))/3)
assert expand_func(airyai(2*(3*z**5)**Rational(1, 3))) == (
-sqrt(3)*(-1 + (z**5)**Rational(1, 3)/z**Rational(5, 3))*airybi(2*3**Rational(1, 3)*z**Rational(5, 3))/6 +
(1 + (z**5)**Rational(1, 3)/z**Rational(5, 3))*airyai(2*3**Rational(1, 3)*z**Rational(5, 3))/2)
def test_airybi():
z = Symbol('z', real=False)
t = Symbol('t', negative=True)
p = Symbol('p', positive=True)
assert isinstance(airybi(z), airybi)
assert airybi(0) == 3**Rational(5, 6)/(3*gamma(Rational(2, 3)))
assert airybi(oo) is oo
assert airybi(-oo) == 0
assert diff(airybi(z), z) == airybiprime(z)
assert series(airybi(z), z, 0, 3) == (
3**Rational(1, 3)*gamma(Rational(1, 3))/(2*pi) + 3**Rational(2, 3)*z*gamma(Rational(2, 3))/(2*pi) + O(z**3))
assert airybi(z).rewrite(hyper) == (
3**Rational(1, 6)*z*hyper((), (Rational(4, 3),), z**3/9)/gamma(Rational(1, 3)) +
3**Rational(5, 6)*hyper((), (Rational(2, 3),), z**3/9)/(3*gamma(Rational(2, 3))))
assert isinstance(airybi(z).rewrite(besselj), airybi)
assert airyai(t).rewrite(besselj) == (
sqrt(-t)*(besselj(Rational(-1, 3), 2*(-t)**Rational(3, 2)/3) +
besselj(Rational(1, 3), 2*(-t)**Rational(3, 2)/3))/3)
assert airybi(z).rewrite(besseli) == (
sqrt(3)*(z*besseli(Rational(1, 3), 2*z**Rational(3, 2)/3)/(z**Rational(3, 2))**Rational(1, 3) +
(z**Rational(3, 2))**Rational(1, 3)*besseli(Rational(-1, 3), 2*z**Rational(3, 2)/3))/3)
assert airybi(p).rewrite(besseli) == (
sqrt(3)*sqrt(p)*(besseli(Rational(-1, 3), 2*p**Rational(3, 2)/3) +
besseli(Rational(1, 3), 2*p**Rational(3, 2)/3))/3)
assert expand_func(airybi(2*(3*z**5)**Rational(1, 3))) == (
sqrt(3)*(1 - (z**5)**Rational(1, 3)/z**Rational(5, 3))*airyai(2*3**Rational(1, 3)*z**Rational(5, 3))/2 +
(1 + (z**5)**Rational(1, 3)/z**Rational(5, 3))*airybi(2*3**Rational(1, 3)*z**Rational(5, 3))/2)
def test_airyaiprime():
z = Symbol('z', real=False)
t = Symbol('t', negative=True)
p = Symbol('p', positive=True)
assert isinstance(airyaiprime(z), airyaiprime)
assert airyaiprime(0) == -3**Rational(2, 3)/(3*gamma(Rational(1, 3)))
assert airyaiprime(oo) == 0
assert diff(airyaiprime(z), z) == z*airyai(z)
assert series(airyaiprime(z), z, 0, 3) == (
-3**Rational(2, 3)/(3*gamma(Rational(1, 3))) + 3**Rational(1, 3)*z**2/(6*gamma(Rational(2, 3))) + O(z**3))
assert airyaiprime(z).rewrite(hyper) == (
3**Rational(1, 3)*z**2*hyper((), (Rational(5, 3),), z**3/9)/(6*gamma(Rational(2, 3))) -
3**Rational(2, 3)*hyper((), (Rational(1, 3),), z**3/9)/(3*gamma(Rational(1, 3))))
assert isinstance(airyaiprime(z).rewrite(besselj), airyaiprime)
assert airyai(t).rewrite(besselj) == (
sqrt(-t)*(besselj(Rational(-1, 3), 2*(-t)**Rational(3, 2)/3) +
besselj(Rational(1, 3), 2*(-t)**Rational(3, 2)/3))/3)
assert airyaiprime(z).rewrite(besseli) == (
z**2*besseli(Rational(2, 3), 2*z**Rational(3, 2)/3)/(3*(z**Rational(3, 2))**Rational(2, 3)) -
(z**Rational(3, 2))**Rational(2, 3)*besseli(Rational(-1, 3), 2*z**Rational(3, 2)/3)/3)
assert airyaiprime(p).rewrite(besseli) == (
p*(-besseli(Rational(-2, 3), 2*p**Rational(3, 2)/3) + besseli(Rational(2, 3), 2*p**Rational(3, 2)/3))/3)
assert expand_func(airyaiprime(2*(3*z**5)**Rational(1, 3))) == (
sqrt(3)*(z**Rational(5, 3)/(z**5)**Rational(1, 3) - 1)*airybiprime(2*3**Rational(1, 3)*z**Rational(5, 3))/6 +
(z**Rational(5, 3)/(z**5)**Rational(1, 3) + 1)*airyaiprime(2*3**Rational(1, 3)*z**Rational(5, 3))/2)
def test_airybiprime():
z = Symbol('z', real=False)
t = Symbol('t', negative=True)
p = Symbol('p', positive=True)
assert isinstance(airybiprime(z), airybiprime)
assert airybiprime(0) == 3**Rational(1, 6)/gamma(Rational(1, 3))
assert airybiprime(oo) is oo
assert airybiprime(-oo) == 0
assert diff(airybiprime(z), z) == z*airybi(z)
assert series(airybiprime(z), z, 0, 3) == (
3**Rational(1, 6)/gamma(Rational(1, 3)) + 3**Rational(5, 6)*z**2/(6*gamma(Rational(2, 3))) + O(z**3))
assert airybiprime(z).rewrite(hyper) == (
3**Rational(5, 6)*z**2*hyper((), (Rational(5, 3),), z**3/9)/(6*gamma(Rational(2, 3))) +
3**Rational(1, 6)*hyper((), (Rational(1, 3),), z**3/9)/gamma(Rational(1, 3)))
assert isinstance(airybiprime(z).rewrite(besselj), airybiprime)
assert airyai(t).rewrite(besselj) == (
sqrt(-t)*(besselj(Rational(-1, 3), 2*(-t)**Rational(3, 2)/3) +
besselj(Rational(1, 3), 2*(-t)**Rational(3, 2)/3))/3)
assert airybiprime(z).rewrite(besseli) == (
sqrt(3)*(z**2*besseli(Rational(2, 3), 2*z**Rational(3, 2)/3)/(z**Rational(3, 2))**Rational(2, 3) +
(z**Rational(3, 2))**Rational(2, 3)*besseli(Rational(-2, 3), 2*z**Rational(3, 2)/3))/3)
assert airybiprime(p).rewrite(besseli) == (
sqrt(3)*p*(besseli(Rational(-2, 3), 2*p**Rational(3, 2)/3) + besseli(Rational(2, 3), 2*p**Rational(3, 2)/3))/3)
assert expand_func(airybiprime(2*(3*z**5)**Rational(1, 3))) == (
sqrt(3)*(z**Rational(5, 3)/(z**5)**Rational(1, 3) - 1)*airyaiprime(2*3**Rational(1, 3)*z**Rational(5, 3))/2 +
(z**Rational(5, 3)/(z**5)**Rational(1, 3) + 1)*airybiprime(2*3**Rational(1, 3)*z**Rational(5, 3))/2)
def test_marcumq():
m = Symbol('m')
a = Symbol('a')
b = Symbol('b')
assert marcumq(0, 0, 0) == 0
assert marcumq(m, 0, b) == uppergamma(m, b**2/2)/gamma(m)
assert marcumq(2, 0, 5) == 27*exp(Rational(-25, 2))/2
assert marcumq(0, a, 0) == 1 - exp(-a**2/2)
assert marcumq(0, pi, 0) == 1 - exp(-pi**2/2)
assert marcumq(1, a, a) == S.Half + exp(-a**2)*besseli(0, a**2)/2
assert marcumq(2, a, a) == S.Half + exp(-a**2)*besseli(0, a**2)/2 + exp(-a**2)*besseli(1, a**2)
assert diff(marcumq(1, a, 3), a) == a*(-marcumq(1, a, 3) + marcumq(2, a, 3))
assert diff(marcumq(2, 3, b), b) == -b**2*exp(-b**2/2 - Rational(9, 2))*besseli(1, 3*b)/3
x = Symbol('x')
assert marcumq(2, 3, 4).rewrite(Integral, x=x) == \
Integral(x**2*exp(-x**2/2 - Rational(9, 2))*besseli(1, 3*x), (x, 4, oo))/3
assert eq([marcumq(5, -2, 3).rewrite(Integral).evalf(10)],
[0.7905769565])
k = Symbol('k')
assert marcumq(-3, -5, -7).rewrite(Sum, k=k) == \
exp(-37)*Sum((Rational(5, 7))**k*besseli(k, 35), (k, 4, oo))
assert eq([marcumq(1, 3, 1).rewrite(Sum).evalf(10)],
[0.9891705502])
assert marcumq(1, a, a, evaluate=False).rewrite(besseli) == S.Half + exp(-a**2)*besseli(0, a**2)/2
assert marcumq(2, a, a, evaluate=False).rewrite(besseli) == S.Half + exp(-a**2)*besseli(0, a**2)/2 + \
exp(-a**2)*besseli(1, a**2)
assert marcumq(3, a, a).rewrite(besseli) == (besseli(1, a**2) + besseli(2, a**2))*exp(-a**2) + \
S.Half + exp(-a**2)*besseli(0, a**2)/2
assert marcumq(5, 8, 8).rewrite(besseli) == exp(-64)*besseli(0, 64)/2 + \
(besseli(4, 64) + besseli(3, 64) + besseli(2, 64) + besseli(1, 64))*exp(-64) + S.Half
assert marcumq(m, a, a).rewrite(besseli) == marcumq(m, a, a)
x = Symbol('x', integer=True)
assert marcumq(x, a, a).rewrite(besseli) == marcumq(x, a, a)
|
d92e04465d1234b2ade0c31f9412487fc440beb7991dcf3cc2f2108d3e323d4d | from sympy import (
nan, pi, symbols, DiracDelta, Symbol, diff,
Piecewise, I, Eq, Derivative, oo, SingularityFunction, Heaviside,
Float, O
)
from sympy.core.expr import unchanged
from sympy.core.function import ArgumentIndexError
from sympy.testing.pytest import raises
x, y, a, n = symbols('x y a n')
def test_fdiff():
assert SingularityFunction(x, 4, 5).fdiff() == 5*SingularityFunction(x, 4, 4)
assert SingularityFunction(x, 4, -1).fdiff() == SingularityFunction(x, 4, -2)
assert SingularityFunction(x, 4, 0).fdiff() == SingularityFunction(x, 4, -1)
assert SingularityFunction(y, 6, 2).diff(y) == 2*SingularityFunction(y, 6, 1)
assert SingularityFunction(y, -4, -1).diff(y) == SingularityFunction(y, -4, -2)
assert SingularityFunction(y, 4, 0).diff(y) == SingularityFunction(y, 4, -1)
assert SingularityFunction(y, 4, 0).diff(y, 2) == SingularityFunction(y, 4, -2)
n = Symbol('n', positive=True)
assert SingularityFunction(x, a, n).fdiff() == n*SingularityFunction(x, a, n - 1)
assert SingularityFunction(y, a, n).diff(y) == n*SingularityFunction(y, a, n - 1)
expr_in = 4*SingularityFunction(x, a, n) + 3*SingularityFunction(x, a, -1) + -10*SingularityFunction(x, a, 0)
expr_out = n*4*SingularityFunction(x, a, n - 1) + 3*SingularityFunction(x, a, -2) - 10*SingularityFunction(x, a, -1)
assert diff(expr_in, x) == expr_out
assert SingularityFunction(x, -10, 5).diff(evaluate=False) == (
Derivative(SingularityFunction(x, -10, 5), x))
raises(ArgumentIndexError, lambda: SingularityFunction(x, 4, 5).fdiff(2))
def test_eval():
assert SingularityFunction(x, a, n).func == SingularityFunction
assert unchanged(SingularityFunction, x, 5, n)
assert SingularityFunction(5, 3, 2) == 4
assert SingularityFunction(3, 5, 1) == 0
assert SingularityFunction(3, 3, 0) == 1
assert SingularityFunction(4, 4, -1) is oo
assert SingularityFunction(4, 2, -1) == 0
assert SingularityFunction(4, 7, -1) == 0
assert SingularityFunction(5, 6, -2) == 0
assert SingularityFunction(4, 2, -2) == 0
assert SingularityFunction(4, 4, -2) is oo
assert (SingularityFunction(6.1, 4, 5)).evalf(5) == Float('40.841', '5')
assert SingularityFunction(6.1, pi, 2) == (-pi + 6.1)**2
assert SingularityFunction(x, a, nan) is nan
assert SingularityFunction(x, nan, 1) is nan
assert SingularityFunction(nan, a, n) is nan
raises(ValueError, lambda: SingularityFunction(x, a, I))
raises(ValueError, lambda: SingularityFunction(2*I, I, n))
raises(ValueError, lambda: SingularityFunction(x, a, -3))
def test_leading_term():
l = Symbol('l', positive=True)
assert SingularityFunction(x, 3, 2).as_leading_term(x) == 0
assert SingularityFunction(x, -2, 1).as_leading_term(x) == 2
assert SingularityFunction(x, 0, 0).as_leading_term(x) == 1
assert SingularityFunction(x, 0, 0).as_leading_term(x, cdir=-1) == 0
assert SingularityFunction(x, 0, -1).as_leading_term(x) == 0
assert SingularityFunction(x, 0, -2).as_leading_term(x) == 0
assert (SingularityFunction(x + l, 0, 1)/2\
- SingularityFunction(x + l, l/2, 1)\
+ SingularityFunction(x + l, l, 1)/2).as_leading_term(x) == -x/2
def test_series():
l = Symbol('l', positive=True)
assert SingularityFunction(x, -3, 2).series(x) == x**2 + 6*x + 9
assert SingularityFunction(x, -2, 1).series(x) == x + 2
assert SingularityFunction(x, 0, 0).series(x) == 1
assert SingularityFunction(x, 0, 0).series(x, dir='-') == 0
assert SingularityFunction(x, 0, -1).series(x) == 0
assert SingularityFunction(x, 0, -2).series(x) == 0
assert (SingularityFunction(x + l, 0, 1)/2\
- SingularityFunction(x + l, l/2, 1)\
+ SingularityFunction(x + l, l, 1)/2).nseries(x) == -x/2 + O(x**6)
def test_rewrite():
assert SingularityFunction(x, 4, 5).rewrite(Piecewise) == (
Piecewise(((x - 4)**5, x - 4 > 0), (0, True)))
assert SingularityFunction(x, -10, 0).rewrite(Piecewise) == (
Piecewise((1, x + 10 > 0), (0, True)))
assert SingularityFunction(x, 2, -1).rewrite(Piecewise) == (
Piecewise((oo, Eq(x - 2, 0)), (0, True)))
assert SingularityFunction(x, 0, -2).rewrite(Piecewise) == (
Piecewise((oo, Eq(x, 0)), (0, True)))
n = Symbol('n', nonnegative=True)
assert SingularityFunction(x, a, n).rewrite(Piecewise) == (
Piecewise(((x - a)**n, x - a > 0), (0, True)))
expr_in = SingularityFunction(x, 4, 5) + SingularityFunction(x, -3, -1) - SingularityFunction(x, 0, -2)
expr_out = (x - 4)**5*Heaviside(x - 4) + DiracDelta(x + 3) - DiracDelta(x, 1)
assert expr_in.rewrite(Heaviside) == expr_out
assert expr_in.rewrite(DiracDelta) == expr_out
assert expr_in.rewrite('HeavisideDiracDelta') == expr_out
expr_in = SingularityFunction(x, a, n) + SingularityFunction(x, a, -1) - SingularityFunction(x, a, -2)
expr_out = (x - a)**n*Heaviside(x - a) + DiracDelta(x - a) + DiracDelta(a - x, 1)
assert expr_in.rewrite(Heaviside) == expr_out
assert expr_in.rewrite(DiracDelta) == expr_out
assert expr_in.rewrite('HeavisideDiracDelta') == expr_out
|
20c02e77cecc3b3d8e4e21682c62f200ffa86f334ccdaa3a608adb909b3ad386 | from sympy import (
symbols, expand, expand_func, nan, oo, Float, conjugate, diff,
re, im, O, exp_polar, polar_lift, gruntz, limit,
Symbol, I, integrate, Integral, S,
sqrt, sin, cos, sinc, sinh, cosh, exp, log, pi, EulerGamma,
erf, erfc, erfi, erf2, erfinv, erfcinv, erf2inv,
gamma, uppergamma,
Ei, expint, E1, li, Li, Si, Ci, Shi, Chi,
fresnels, fresnelc,
hyper, meijerg, E, Rational)
from sympy.core.expr import unchanged
from sympy.core.function import ArgumentIndexError
from sympy.functions.special.error_functions import _erfs, _eis
from sympy.testing.pytest import raises, slow
x, y, z = symbols('x,y,z')
w = Symbol("w", real=True)
n = Symbol("n", integer=True)
def test_erf():
assert erf(nan) is nan
assert erf(oo) == 1
assert erf(-oo) == -1
assert erf(0) == 0
assert erf(I*oo) == oo*I
assert erf(-I*oo) == -oo*I
assert erf(-2) == -erf(2)
assert erf(-x*y) == -erf(x*y)
assert erf(-x - y) == -erf(x + y)
assert erf(erfinv(x)) == x
assert erf(erfcinv(x)) == 1 - x
assert erf(erf2inv(0, x)) == x
assert erf(erf2inv(0, x, evaluate=False)) == x # To cover code in erf
assert erf(erf2inv(0, erf(erfcinv(1 - erf(erfinv(x)))))) == x
assert erf(I).is_real is False
assert erf(0).is_real is True
assert conjugate(erf(z)) == erf(conjugate(z))
assert erf(x).as_leading_term(x) == 2*x/sqrt(pi)
assert erf(x*y).as_leading_term(y) == 2*x*y/sqrt(pi)
assert (erf(x*y)/erf(y)).as_leading_term(y) == x
assert erf(1/x).as_leading_term(x) == S.One
assert erf(z).rewrite('uppergamma') == sqrt(z**2)*(1 - erfc(sqrt(z**2)))/z
assert erf(z).rewrite('erfc') == S.One - erfc(z)
assert erf(z).rewrite('erfi') == -I*erfi(I*z)
assert erf(z).rewrite('fresnels') == (1 + I)*(fresnelc(z*(1 - I)/sqrt(pi)) -
I*fresnels(z*(1 - I)/sqrt(pi)))
assert erf(z).rewrite('fresnelc') == (1 + I)*(fresnelc(z*(1 - I)/sqrt(pi)) -
I*fresnels(z*(1 - I)/sqrt(pi)))
assert erf(z).rewrite('hyper') == 2*z*hyper([S.Half], [3*S.Half], -z**2)/sqrt(pi)
assert erf(z).rewrite('meijerg') == z*meijerg([S.Half], [], [0], [Rational(-1, 2)], z**2)/sqrt(pi)
assert erf(z).rewrite('expint') == sqrt(z**2)/z - z*expint(S.Half, z**2)/sqrt(S.Pi)
assert limit(exp(x)*exp(x**2)*(erf(x + 1/exp(x)) - erf(x)), x, oo) == \
2/sqrt(pi)
assert limit((1 - erf(z))*exp(z**2)*z, z, oo) == 1/sqrt(pi)
assert limit((1 - erf(x))*exp(x**2)*sqrt(pi)*x, x, oo) == 1
assert limit(((1 - erf(x))*exp(x**2)*sqrt(pi)*x - 1)*2*x**2, x, oo) == -1
assert limit(erf(x)/x, x, 0) == 2/sqrt(pi)
assert limit(x**(-4) - sqrt(pi)*erf(x**2) / (2*x**6), x, 0) == S(1)/3
assert erf(x).as_real_imag() == \
(erf(re(x) - I*im(x))/2 + erf(re(x) + I*im(x))/2,
-I*(-erf(re(x) - I*im(x)) + erf(re(x) + I*im(x)))/2)
assert erf(x).as_real_imag(deep=False) == \
(erf(re(x) - I*im(x))/2 + erf(re(x) + I*im(x))/2,
-I*(-erf(re(x) - I*im(x)) + erf(re(x) + I*im(x)))/2)
assert erf(w).as_real_imag() == (erf(w), 0)
assert erf(w).as_real_imag(deep=False) == (erf(w), 0)
# issue 13575
assert erf(I).as_real_imag() == (0, -I*erf(I))
raises(ArgumentIndexError, lambda: erf(x).fdiff(2))
assert erf(x).inverse() == erfinv
def test_erf_series():
assert erf(x).series(x, 0, 7) == 2*x/sqrt(pi) - \
2*x**3/3/sqrt(pi) + x**5/5/sqrt(pi) + O(x**7)
assert erf(x).series(x, oo) == \
-exp(-x**2)*(3/(4*x**5) - 1/(2*x**3) + 1/x + O(x**(-6), (x, oo)))/sqrt(pi) + 1
assert erf(x**2).series(x, oo, n=8) == \
(-1/(2*x**6) + x**(-2) + O(x**(-8), (x, oo)))*exp(-x**4)/sqrt(pi)*-1 + 1
assert erf(sqrt(x)).series(x, oo, n=3) == (sqrt(1/x) - (1/x)**(S(3)/2)/2\
+ 3*(1/x)**(S(5)/2)/4 + O(x**(-3), (x, oo)))*exp(-x)/sqrt(pi)*-1 + 1
def test_erf_evalf():
assert abs( erf(Float(2.0)) - 0.995322265 ) < 1E-8 # XXX
def test__erfs():
assert _erfs(z).diff(z) == -2/sqrt(S.Pi) + 2*z*_erfs(z)
assert _erfs(1/z).series(z) == \
z/sqrt(pi) - z**3/(2*sqrt(pi)) + 3*z**5/(4*sqrt(pi)) + O(z**6)
assert expand(erf(z).rewrite('tractable').diff(z).rewrite('intractable')) \
== erf(z).diff(z)
assert _erfs(z).rewrite("intractable") == (-erf(z) + 1)*exp(z**2)
raises(ArgumentIndexError, lambda: _erfs(z).fdiff(2))
def test_erfc():
assert erfc(nan) is nan
assert erfc(oo) == 0
assert erfc(-oo) == 2
assert erfc(0) == 1
assert erfc(I*oo) == -oo*I
assert erfc(-I*oo) == oo*I
assert erfc(-x) == S(2) - erfc(x)
assert erfc(erfcinv(x)) == x
assert erfc(I).is_real is False
assert erfc(0).is_real is True
assert erfc(erfinv(x)) == 1 - x
assert conjugate(erfc(z)) == erfc(conjugate(z))
assert erfc(x).as_leading_term(x) is S.One
assert erfc(1/x).as_leading_term(x) == S.Zero
assert erfc(z).rewrite('erf') == 1 - erf(z)
assert erfc(z).rewrite('erfi') == 1 + I*erfi(I*z)
assert erfc(z).rewrite('fresnels') == 1 - (1 + I)*(fresnelc(z*(1 - I)/sqrt(pi)) -
I*fresnels(z*(1 - I)/sqrt(pi)))
assert erfc(z).rewrite('fresnelc') == 1 - (1 + I)*(fresnelc(z*(1 - I)/sqrt(pi)) -
I*fresnels(z*(1 - I)/sqrt(pi)))
assert erfc(z).rewrite('hyper') == 1 - 2*z*hyper([S.Half], [3*S.Half], -z**2)/sqrt(pi)
assert erfc(z).rewrite('meijerg') == 1 - z*meijerg([S.Half], [], [0], [Rational(-1, 2)], z**2)/sqrt(pi)
assert erfc(z).rewrite('uppergamma') == 1 - sqrt(z**2)*(1 - erfc(sqrt(z**2)))/z
assert erfc(z).rewrite('expint') == S.One - sqrt(z**2)/z + z*expint(S.Half, z**2)/sqrt(S.Pi)
assert erfc(z).rewrite('tractable') == _erfs(z)*exp(-z**2)
assert expand_func(erf(x) + erfc(x)) is S.One
assert erfc(x).as_real_imag() == \
(erfc(re(x) - I*im(x))/2 + erfc(re(x) + I*im(x))/2,
-I*(-erfc(re(x) - I*im(x)) + erfc(re(x) + I*im(x)))/2)
assert erfc(x).as_real_imag(deep=False) == \
(erfc(re(x) - I*im(x))/2 + erfc(re(x) + I*im(x))/2,
-I*(-erfc(re(x) - I*im(x)) + erfc(re(x) + I*im(x)))/2)
assert erfc(w).as_real_imag() == (erfc(w), 0)
assert erfc(w).as_real_imag(deep=False) == (erfc(w), 0)
raises(ArgumentIndexError, lambda: erfc(x).fdiff(2))
assert erfc(x).inverse() == erfcinv
def test_erfc_series():
assert erfc(x).series(x, 0, 7) == 1 - 2*x/sqrt(pi) + \
2*x**3/3/sqrt(pi) - x**5/5/sqrt(pi) + O(x**7)
assert erfc(x).series(x, oo) == \
(3/(4*x**5) - 1/(2*x**3) + 1/x + O(x**(-6), (x, oo)))*exp(-x**2)/sqrt(pi)
def test_erfc_evalf():
assert abs( erfc(Float(2.0)) - 0.00467773 ) < 1E-8 # XXX
def test_erfi():
assert erfi(nan) is nan
assert erfi(oo) is S.Infinity
assert erfi(-oo) is S.NegativeInfinity
assert erfi(0) is S.Zero
assert erfi(I*oo) == I
assert erfi(-I*oo) == -I
assert erfi(-x) == -erfi(x)
assert erfi(I*erfinv(x)) == I*x
assert erfi(I*erfcinv(x)) == I*(1 - x)
assert erfi(I*erf2inv(0, x)) == I*x
assert erfi(I*erf2inv(0, x, evaluate=False)) == I*x # To cover code in erfi
assert erfi(I).is_real is False
assert erfi(0).is_real is True
assert conjugate(erfi(z)) == erfi(conjugate(z))
assert erfi(x).as_leading_term(x) == 2*x/sqrt(pi)
assert erfi(x*y).as_leading_term(y) == 2*x*y/sqrt(pi)
assert (erfi(x*y)/erfi(y)).as_leading_term(y) == x
assert erfi(1/x).as_leading_term(x) == erfi(1/x)
assert erfi(z).rewrite('erf') == -I*erf(I*z)
assert erfi(z).rewrite('erfc') == I*erfc(I*z) - I
assert erfi(z).rewrite('fresnels') == (1 - I)*(fresnelc(z*(1 + I)/sqrt(pi)) -
I*fresnels(z*(1 + I)/sqrt(pi)))
assert erfi(z).rewrite('fresnelc') == (1 - I)*(fresnelc(z*(1 + I)/sqrt(pi)) -
I*fresnels(z*(1 + I)/sqrt(pi)))
assert erfi(z).rewrite('hyper') == 2*z*hyper([S.Half], [3*S.Half], z**2)/sqrt(pi)
assert erfi(z).rewrite('meijerg') == z*meijerg([S.Half], [], [0], [Rational(-1, 2)], -z**2)/sqrt(pi)
assert erfi(z).rewrite('uppergamma') == (sqrt(-z**2)/z*(uppergamma(S.Half,
-z**2)/sqrt(S.Pi) - S.One))
assert erfi(z).rewrite('expint') == sqrt(-z**2)/z - z*expint(S.Half, -z**2)/sqrt(S.Pi)
assert erfi(z).rewrite('tractable') == -I*(-_erfs(I*z)*exp(z**2) + 1)
assert expand_func(erfi(I*z)) == I*erf(z)
assert erfi(x).as_real_imag() == \
(erfi(re(x) - I*im(x))/2 + erfi(re(x) + I*im(x))/2,
-I*(-erfi(re(x) - I*im(x)) + erfi(re(x) + I*im(x)))/2)
assert erfi(x).as_real_imag(deep=False) == \
(erfi(re(x) - I*im(x))/2 + erfi(re(x) + I*im(x))/2,
-I*(-erfi(re(x) - I*im(x)) + erfi(re(x) + I*im(x)))/2)
assert erfi(w).as_real_imag() == (erfi(w), 0)
assert erfi(w).as_real_imag(deep=False) == (erfi(w), 0)
raises(ArgumentIndexError, lambda: erfi(x).fdiff(2))
def test_erfi_series():
assert erfi(x).series(x, 0, 7) == 2*x/sqrt(pi) + \
2*x**3/3/sqrt(pi) + x**5/5/sqrt(pi) + O(x**7)
assert erfi(x).series(x, oo) == \
(3/(4*x**5) + 1/(2*x**3) + 1/x + O(x**(-6), (x, oo)))*exp(x**2)/sqrt(pi) - I
def test_erfi_evalf():
assert abs( erfi(Float(2.0)) - 18.5648024145756 ) < 1E-13 # XXX
def test_erf2():
assert erf2(0, 0) is S.Zero
assert erf2(x, x) is S.Zero
assert erf2(nan, 0) is nan
assert erf2(-oo, y) == erf(y) + 1
assert erf2( oo, y) == erf(y) - 1
assert erf2( x, oo) == 1 - erf(x)
assert erf2( x,-oo) == -1 - erf(x)
assert erf2(x, erf2inv(x, y)) == y
assert erf2(-x, -y) == -erf2(x,y)
assert erf2(-x, y) == erf(y) + erf(x)
assert erf2( x, -y) == -erf(y) - erf(x)
assert erf2(x, y).rewrite('fresnels') == erf(y).rewrite(fresnels)-erf(x).rewrite(fresnels)
assert erf2(x, y).rewrite('fresnelc') == erf(y).rewrite(fresnelc)-erf(x).rewrite(fresnelc)
assert erf2(x, y).rewrite('hyper') == erf(y).rewrite(hyper)-erf(x).rewrite(hyper)
assert erf2(x, y).rewrite('meijerg') == erf(y).rewrite(meijerg)-erf(x).rewrite(meijerg)
assert erf2(x, y).rewrite('uppergamma') == erf(y).rewrite(uppergamma) - erf(x).rewrite(uppergamma)
assert erf2(x, y).rewrite('expint') == erf(y).rewrite(expint)-erf(x).rewrite(expint)
assert erf2(I, 0).is_real is False
assert erf2(0, 0).is_real is True
assert expand_func(erf(x) + erf2(x, y)) == erf(y)
assert conjugate(erf2(x, y)) == erf2(conjugate(x), conjugate(y))
assert erf2(x, y).rewrite('erf') == erf(y) - erf(x)
assert erf2(x, y).rewrite('erfc') == erfc(x) - erfc(y)
assert erf2(x, y).rewrite('erfi') == I*(erfi(I*x) - erfi(I*y))
assert erf2(x, y).diff(x) == erf2(x, y).fdiff(1)
assert erf2(x, y).diff(y) == erf2(x, y).fdiff(2)
assert erf2(x, y).diff(x) == -2*exp(-x**2)/sqrt(pi)
assert erf2(x, y).diff(y) == 2*exp(-y**2)/sqrt(pi)
raises(ArgumentIndexError, lambda: erf2(x, y).fdiff(3))
assert erf2(x, y).is_extended_real is None
xr, yr = symbols('xr yr', extended_real=True)
assert erf2(xr, yr).is_extended_real is True
def test_erfinv():
assert erfinv(0) == 0
assert erfinv(1) is S.Infinity
assert erfinv(nan) is S.NaN
assert erfinv(-1) is S.NegativeInfinity
assert erfinv(erf(w)) == w
assert erfinv(erf(-w)) == -w
assert erfinv(x).diff() == sqrt(pi)*exp(erfinv(x)**2)/2
raises(ArgumentIndexError, lambda: erfinv(x).fdiff(2))
assert erfinv(z).rewrite('erfcinv') == erfcinv(1-z)
assert erfinv(z).inverse() == erf
def test_erfinv_evalf():
assert abs( erfinv(Float(0.2)) - 0.179143454621292 ) < 1E-13
def test_erfcinv():
assert erfcinv(1) == 0
assert erfcinv(0) is S.Infinity
assert erfcinv(nan) is S.NaN
assert erfcinv(x).diff() == -sqrt(pi)*exp(erfcinv(x)**2)/2
raises(ArgumentIndexError, lambda: erfcinv(x).fdiff(2))
assert erfcinv(z).rewrite('erfinv') == erfinv(1-z)
assert erfcinv(z).inverse() == erfc
def test_erf2inv():
assert erf2inv(0, 0) is S.Zero
assert erf2inv(0, 1) is S.Infinity
assert erf2inv(1, 0) is S.One
assert erf2inv(0, y) == erfinv(y)
assert erf2inv(oo, y) == erfcinv(-y)
assert erf2inv(x, 0) == x
assert erf2inv(x, oo) == erfinv(x)
assert erf2inv(nan, 0) is nan
assert erf2inv(0, nan) is nan
assert erf2inv(x, y).diff(x) == exp(-x**2 + erf2inv(x, y)**2)
assert erf2inv(x, y).diff(y) == sqrt(pi)*exp(erf2inv(x, y)**2)/2
raises(ArgumentIndexError, lambda: erf2inv(x, y).fdiff(3))
# NOTE we multiply by exp_polar(I*pi) and need this to be on the principal
# branch, hence take x in the lower half plane (d=0).
def mytn(expr1, expr2, expr3, x, d=0):
from sympy.testing.randtest import verify_numerically, random_complex_number
subs = {}
for a in expr1.free_symbols:
if a != x:
subs[a] = random_complex_number()
return expr2 == expr3 and verify_numerically(expr1.subs(subs),
expr2.subs(subs), x, d=d)
def mytd(expr1, expr2, x):
from sympy.testing.randtest import test_derivative_numerically, \
random_complex_number
subs = {}
for a in expr1.free_symbols:
if a != x:
subs[a] = random_complex_number()
return expr1.diff(x) == expr2 and test_derivative_numerically(expr1.subs(subs), x)
def tn_branch(func, s=None):
from random import uniform
def fn(x):
if s is None:
return func(x)
return func(s, x)
c = uniform(1, 5)
expr = fn(c*exp_polar(I*pi)) - fn(c*exp_polar(-I*pi))
eps = 1e-15
expr2 = fn(-c + eps*I) - fn(-c - eps*I)
return abs(expr.n() - expr2.n()).n() < 1e-10
def test_ei():
assert Ei(0) is S.NegativeInfinity
assert Ei(oo) is S.Infinity
assert Ei(-oo) is S.Zero
assert tn_branch(Ei)
assert mytd(Ei(x), exp(x)/x, x)
assert mytn(Ei(x), Ei(x).rewrite(uppergamma),
-uppergamma(0, x*polar_lift(-1)) - I*pi, x)
assert mytn(Ei(x), Ei(x).rewrite(expint),
-expint(1, x*polar_lift(-1)) - I*pi, x)
assert Ei(x).rewrite(expint).rewrite(Ei) == Ei(x)
assert Ei(x*exp_polar(2*I*pi)) == Ei(x) + 2*I*pi
assert Ei(x*exp_polar(-2*I*pi)) == Ei(x) - 2*I*pi
assert mytn(Ei(x), Ei(x).rewrite(Shi), Chi(x) + Shi(x), x)
assert mytn(Ei(x*polar_lift(I)), Ei(x*polar_lift(I)).rewrite(Si),
Ci(x) + I*Si(x) + I*pi/2, x)
assert Ei(log(x)).rewrite(li) == li(x)
assert Ei(2*log(x)).rewrite(li) == li(x**2)
assert gruntz(Ei(x+exp(-x))*exp(-x)*x, x, oo) == 1
assert Ei(x).series(x) == EulerGamma + log(x) + x + x**2/4 + \
x**3/18 + x**4/96 + x**5/600 + O(x**6)
assert Ei(x).series(x, 1, 3) == Ei(1) + E*(x - 1) + O((x - 1)**3, (x, 1))
assert Ei(x).series(x, oo) == \
(120/x**5 + 24/x**4 + 6/x**3 + 2/x**2 + 1/x + 1 + O(x**(-6), (x, oo)))*exp(x)/x
assert str(Ei(cos(2)).evalf(n=10)) == '-0.6760647401'
raises(ArgumentIndexError, lambda: Ei(x).fdiff(2))
def test_expint():
assert mytn(expint(x, y), expint(x, y).rewrite(uppergamma),
y**(x - 1)*uppergamma(1 - x, y), x)
assert mytd(
expint(x, y), -y**(x - 1)*meijerg([], [1, 1], [0, 0, 1 - x], [], y), x)
assert mytd(expint(x, y), -expint(x - 1, y), y)
assert mytn(expint(1, x), expint(1, x).rewrite(Ei),
-Ei(x*polar_lift(-1)) + I*pi, x)
assert expint(-4, x) == exp(-x)/x + 4*exp(-x)/x**2 + 12*exp(-x)/x**3 \
+ 24*exp(-x)/x**4 + 24*exp(-x)/x**5
assert expint(Rational(-3, 2), x) == \
exp(-x)/x + 3*exp(-x)/(2*x**2) + 3*sqrt(pi)*erfc(sqrt(x))/(4*x**S('5/2'))
assert tn_branch(expint, 1)
assert tn_branch(expint, 2)
assert tn_branch(expint, 3)
assert tn_branch(expint, 1.7)
assert tn_branch(expint, pi)
assert expint(y, x*exp_polar(2*I*pi)) == \
x**(y - 1)*(exp(2*I*pi*y) - 1)*gamma(-y + 1) + expint(y, x)
assert expint(y, x*exp_polar(-2*I*pi)) == \
x**(y - 1)*(exp(-2*I*pi*y) - 1)*gamma(-y + 1) + expint(y, x)
assert expint(2, x*exp_polar(2*I*pi)) == 2*I*pi*x + expint(2, x)
assert expint(2, x*exp_polar(-2*I*pi)) == -2*I*pi*x + expint(2, x)
assert expint(1, x).rewrite(Ei).rewrite(expint) == expint(1, x)
assert expint(x, y).rewrite(Ei) == expint(x, y)
assert expint(x, y).rewrite(Ci) == expint(x, y)
assert mytn(E1(x), E1(x).rewrite(Shi), Shi(x) - Chi(x), x)
assert mytn(E1(polar_lift(I)*x), E1(polar_lift(I)*x).rewrite(Si),
-Ci(x) + I*Si(x) - I*pi/2, x)
assert mytn(expint(2, x), expint(2, x).rewrite(Ei).rewrite(expint),
-x*E1(x) + exp(-x), x)
assert mytn(expint(3, x), expint(3, x).rewrite(Ei).rewrite(expint),
x**2*E1(x)/2 + (1 - x)*exp(-x)/2, x)
assert expint(Rational(3, 2), z).nseries(z) == \
2 + 2*z - z**2/3 + z**3/15 - z**4/84 + z**5/540 - \
2*sqrt(pi)*sqrt(z) + O(z**6)
assert E1(z).series(z) == -EulerGamma - log(z) + z - \
z**2/4 + z**3/18 - z**4/96 + z**5/600 + O(z**6)
assert expint(4, z).series(z) == Rational(1, 3) - z/2 + z**2/2 + \
z**3*(log(z)/6 - Rational(11, 36) + EulerGamma/6 - I*pi/6) - z**4/24 + \
z**5/240 + O(z**6)
assert expint(n, x).series(x, oo, n=3) == \
(n*(n + 1)/x**2 - n/x + 1 + O(x**(-3), (x, oo)))*exp(-x)/x
assert expint(z, y).series(z, 0, 2) == exp(-y)/y - z*meijerg(((), (1, 1)),
((0, 0, 1), ()), y)/y + O(z**2)
raises(ArgumentIndexError, lambda: expint(x, y).fdiff(3))
neg = Symbol('neg', negative=True)
assert Ei(neg).rewrite(Si) == Shi(neg) + Chi(neg) - I*pi
def test__eis():
assert _eis(z).diff(z) == -_eis(z) + 1/z
assert _eis(1/z).series(z) == \
z + z**2 + 2*z**3 + 6*z**4 + 24*z**5 + O(z**6)
assert Ei(z).rewrite('tractable') == exp(z)*_eis(z)
assert li(z).rewrite('tractable') == z*_eis(log(z))
assert _eis(z).rewrite('intractable') == exp(-z)*Ei(z)
assert expand(li(z).rewrite('tractable').diff(z).rewrite('intractable')) \
== li(z).diff(z)
assert expand(Ei(z).rewrite('tractable').diff(z).rewrite('intractable')) \
== Ei(z).diff(z)
assert _eis(z).series(z, n=3) == EulerGamma + log(z) + z*(-log(z) - \
EulerGamma + 1) + z**2*(log(z)/2 - Rational(3, 4) + EulerGamma/2)\
+ O(z**3*log(z))
raises(ArgumentIndexError, lambda: _eis(z).fdiff(2))
def tn_arg(func):
def test(arg, e1, e2):
from random import uniform
v = uniform(1, 5)
v1 = func(arg*x).subs(x, v).n()
v2 = func(e1*v + e2*1e-15).n()
return abs(v1 - v2).n() < 1e-10
return test(exp_polar(I*pi/2), I, 1) and \
test(exp_polar(-I*pi/2), -I, 1) and \
test(exp_polar(I*pi), -1, I) and \
test(exp_polar(-I*pi), -1, -I)
def test_li():
z = Symbol("z")
zr = Symbol("z", real=True)
zp = Symbol("z", positive=True)
zn = Symbol("z", negative=True)
assert li(0) == 0
assert li(1) is -oo
assert li(oo) is oo
assert isinstance(li(z), li)
assert unchanged(li, -zp)
assert unchanged(li, zn)
assert diff(li(z), z) == 1/log(z)
assert conjugate(li(z)) == li(conjugate(z))
assert conjugate(li(-zr)) == li(-zr)
assert unchanged(conjugate, li(-zp))
assert unchanged(conjugate, li(zn))
assert li(z).rewrite(Li) == Li(z) + li(2)
assert li(z).rewrite(Ei) == Ei(log(z))
assert li(z).rewrite(uppergamma) == (-log(1/log(z))/2 - log(-log(z)) +
log(log(z))/2 - expint(1, -log(z)))
assert li(z).rewrite(Si) == (-log(I*log(z)) - log(1/log(z))/2 +
log(log(z))/2 + Ci(I*log(z)) + Shi(log(z)))
assert li(z).rewrite(Ci) == (-log(I*log(z)) - log(1/log(z))/2 +
log(log(z))/2 + Ci(I*log(z)) + Shi(log(z)))
assert li(z).rewrite(Shi) == (-log(1/log(z))/2 + log(log(z))/2 +
Chi(log(z)) - Shi(log(z)))
assert li(z).rewrite(Chi) == (-log(1/log(z))/2 + log(log(z))/2 +
Chi(log(z)) - Shi(log(z)))
assert li(z).rewrite(hyper) ==(log(z)*hyper((1, 1), (2, 2), log(z)) -
log(1/log(z))/2 + log(log(z))/2 + EulerGamma)
assert li(z).rewrite(meijerg) == (-log(1/log(z))/2 - log(-log(z)) + log(log(z))/2 -
meijerg(((), (1,)), ((0, 0), ()), -log(z)))
assert gruntz(1/li(z), z, oo) == 0
assert li(z).series(z) == log(z)**5/600 + log(z)**4/96 + log(z)**3/18 + log(z)**2/4 + \
log(z) + log(log(z)) + EulerGamma
raises(ArgumentIndexError, lambda: li(z).fdiff(2))
def test_Li():
assert Li(2) == 0
assert Li(oo) is oo
assert isinstance(Li(z), Li)
assert diff(Li(z), z) == 1/log(z)
assert gruntz(1/Li(z), z, oo) == 0
assert Li(z).rewrite(li) == li(z) - li(2)
assert Li(z).series(z) == \
log(z)**5/600 + log(z)**4/96 + log(z)**3/18 + log(z)**2/4 + log(z) + log(log(z)) - li(2) + EulerGamma
raises(ArgumentIndexError, lambda: Li(z).fdiff(2))
def test_si():
assert Si(I*x) == I*Shi(x)
assert Shi(I*x) == I*Si(x)
assert Si(-I*x) == -I*Shi(x)
assert Shi(-I*x) == -I*Si(x)
assert Si(-x) == -Si(x)
assert Shi(-x) == -Shi(x)
assert Si(exp_polar(2*pi*I)*x) == Si(x)
assert Si(exp_polar(-2*pi*I)*x) == Si(x)
assert Shi(exp_polar(2*pi*I)*x) == Shi(x)
assert Shi(exp_polar(-2*pi*I)*x) == Shi(x)
assert Si(oo) == pi/2
assert Si(-oo) == -pi/2
assert Shi(oo) is oo
assert Shi(-oo) is -oo
assert mytd(Si(x), sin(x)/x, x)
assert mytd(Shi(x), sinh(x)/x, x)
assert mytn(Si(x), Si(x).rewrite(Ei),
-I*(-Ei(x*exp_polar(-I*pi/2))/2
+ Ei(x*exp_polar(I*pi/2))/2 - I*pi) + pi/2, x)
assert mytn(Si(x), Si(x).rewrite(expint),
-I*(-expint(1, x*exp_polar(-I*pi/2))/2 +
expint(1, x*exp_polar(I*pi/2))/2) + pi/2, x)
assert mytn(Shi(x), Shi(x).rewrite(Ei),
Ei(x)/2 - Ei(x*exp_polar(I*pi))/2 + I*pi/2, x)
assert mytn(Shi(x), Shi(x).rewrite(expint),
expint(1, x)/2 - expint(1, x*exp_polar(I*pi))/2 - I*pi/2, x)
assert tn_arg(Si)
assert tn_arg(Shi)
assert Si(x).nseries(x, n=8) == \
x - x**3/18 + x**5/600 - x**7/35280 + O(x**9)
assert Shi(x).nseries(x, n=8) == \
x + x**3/18 + x**5/600 + x**7/35280 + O(x**9)
assert Si(sin(x)).nseries(x, n=5) == x - 2*x**3/9 + 17*x**5/450 + O(x**6)
assert Si(x).nseries(x, 1, n=3) == \
Si(1) + (x - 1)*sin(1) + (x - 1)**2*(-sin(1)/2 + cos(1)/2) + O((x - 1)**3, (x, 1))
assert Si(x).series(x, oo) == pi/2 - (- 6/x**3 + 1/x \
+ O(x**(-7), (x, oo)))*sin(x)/x - (24/x**4 - 2/x**2 + 1 \
+ O(x**(-7), (x, oo)))*cos(x)/x
t = Symbol('t', Dummy=True)
assert Si(x).rewrite(sinc) == Integral(sinc(t), (t, 0, x))
def test_ci():
m1 = exp_polar(I*pi)
m1_ = exp_polar(-I*pi)
pI = exp_polar(I*pi/2)
mI = exp_polar(-I*pi/2)
assert Ci(m1*x) == Ci(x) + I*pi
assert Ci(m1_*x) == Ci(x) - I*pi
assert Ci(pI*x) == Chi(x) + I*pi/2
assert Ci(mI*x) == Chi(x) - I*pi/2
assert Chi(m1*x) == Chi(x) + I*pi
assert Chi(m1_*x) == Chi(x) - I*pi
assert Chi(pI*x) == Ci(x) + I*pi/2
assert Chi(mI*x) == Ci(x) - I*pi/2
assert Ci(exp_polar(2*I*pi)*x) == Ci(x) + 2*I*pi
assert Chi(exp_polar(-2*I*pi)*x) == Chi(x) - 2*I*pi
assert Chi(exp_polar(2*I*pi)*x) == Chi(x) + 2*I*pi
assert Ci(exp_polar(-2*I*pi)*x) == Ci(x) - 2*I*pi
assert Ci(oo) == 0
assert Ci(-oo) == I*pi
assert Chi(oo) is oo
assert Chi(-oo) is oo
assert mytd(Ci(x), cos(x)/x, x)
assert mytd(Chi(x), cosh(x)/x, x)
assert mytn(Ci(x), Ci(x).rewrite(Ei),
Ei(x*exp_polar(-I*pi/2))/2 + Ei(x*exp_polar(I*pi/2))/2, x)
assert mytn(Chi(x), Chi(x).rewrite(Ei),
Ei(x)/2 + Ei(x*exp_polar(I*pi))/2 - I*pi/2, x)
assert tn_arg(Ci)
assert tn_arg(Chi)
assert Ci(x).nseries(x, n=4) == \
EulerGamma + log(x) - x**2/4 + x**4/96 + O(x**5)
assert Chi(x).nseries(x, n=4) == \
EulerGamma + log(x) + x**2/4 + x**4/96 + O(x**5)
assert Ci(x).series(x, oo) == -cos(x)*(-6/x**3 + 1/x \
+ O(x**(-7), (x, oo)))/x + (24/x**4 - 2/x**2 + 1 \
+ O(x**(-7), (x, oo)))*sin(x)/x
assert limit(log(x) - Ci(2*x), x, 0) == -log(2) - EulerGamma
assert Ci(x).rewrite(uppergamma) == -expint(1, x*exp_polar(-I*pi/2))/2 -\
expint(1, x*exp_polar(I*pi/2))/2
assert Ci(x).rewrite(expint) == -expint(1, x*exp_polar(-I*pi/2))/2 -\
expint(1, x*exp_polar(I*pi/2))/2
raises(ArgumentIndexError, lambda: Ci(x).fdiff(2))
def test_fresnel():
assert fresnels(0) == 0
assert fresnels(oo) == S.Half
assert fresnels(-oo) == Rational(-1, 2)
assert fresnels(I*oo) == -I*S.Half
assert unchanged(fresnels, z)
assert fresnels(-z) == -fresnels(z)
assert fresnels(I*z) == -I*fresnels(z)
assert fresnels(-I*z) == I*fresnels(z)
assert conjugate(fresnels(z)) == fresnels(conjugate(z))
assert fresnels(z).diff(z) == sin(pi*z**2/2)
assert fresnels(z).rewrite(erf) == (S.One + I)/4 * (
erf((S.One + I)/2*sqrt(pi)*z) - I*erf((S.One - I)/2*sqrt(pi)*z))
assert fresnels(z).rewrite(hyper) == \
pi*z**3/6 * hyper([Rational(3, 4)], [Rational(3, 2), Rational(7, 4)], -pi**2*z**4/16)
assert fresnels(z).series(z, n=15) == \
pi*z**3/6 - pi**3*z**7/336 + pi**5*z**11/42240 + O(z**15)
assert fresnels(w).is_extended_real is True
assert fresnels(w).is_finite is True
assert fresnels(z).is_extended_real is None
assert fresnels(z).is_finite is None
assert fresnels(z).as_real_imag() == (fresnels(re(z) - I*im(z))/2 +
fresnels(re(z) + I*im(z))/2,
-I*(-fresnels(re(z) - I*im(z)) + fresnels(re(z) + I*im(z)))/2)
assert fresnels(z).as_real_imag(deep=False) == (fresnels(re(z) - I*im(z))/2 +
fresnels(re(z) + I*im(z))/2,
-I*(-fresnels(re(z) - I*im(z)) + fresnels(re(z) + I*im(z)))/2)
assert fresnels(w).as_real_imag() == (fresnels(w), 0)
assert fresnels(w).as_real_imag(deep=True) == (fresnels(w), 0)
assert fresnels(2 + 3*I).as_real_imag() == (
fresnels(2 + 3*I)/2 + fresnels(2 - 3*I)/2,
-I*(fresnels(2 + 3*I) - fresnels(2 - 3*I))/2
)
assert expand_func(integrate(fresnels(z), z)) == \
z*fresnels(z) + cos(pi*z**2/2)/pi
assert fresnels(z).rewrite(meijerg) == sqrt(2)*pi*z**Rational(9, 4) * \
meijerg(((), (1,)), ((Rational(3, 4),),
(Rational(1, 4), 0)), -pi**2*z**4/16)/(2*(-z)**Rational(3, 4)*(z**2)**Rational(3, 4))
assert fresnelc(0) == 0
assert fresnelc(oo) == S.Half
assert fresnelc(-oo) == Rational(-1, 2)
assert fresnelc(I*oo) == I*S.Half
assert unchanged(fresnelc, z)
assert fresnelc(-z) == -fresnelc(z)
assert fresnelc(I*z) == I*fresnelc(z)
assert fresnelc(-I*z) == -I*fresnelc(z)
assert conjugate(fresnelc(z)) == fresnelc(conjugate(z))
assert fresnelc(z).diff(z) == cos(pi*z**2/2)
assert fresnelc(z).rewrite(erf) == (S.One - I)/4 * (
erf((S.One + I)/2*sqrt(pi)*z) + I*erf((S.One - I)/2*sqrt(pi)*z))
assert fresnelc(z).rewrite(hyper) == \
z * hyper([Rational(1, 4)], [S.Half, Rational(5, 4)], -pi**2*z**4/16)
assert fresnelc(w).is_extended_real is True
assert fresnelc(z).as_real_imag() == \
(fresnelc(re(z) - I*im(z))/2 + fresnelc(re(z) + I*im(z))/2,
-I*(-fresnelc(re(z) - I*im(z)) + fresnelc(re(z) + I*im(z)))/2)
assert fresnelc(z).as_real_imag(deep=False) == \
(fresnelc(re(z) - I*im(z))/2 + fresnelc(re(z) + I*im(z))/2,
-I*(-fresnelc(re(z) - I*im(z)) + fresnelc(re(z) + I*im(z)))/2)
assert fresnelc(2 + 3*I).as_real_imag() == (
fresnelc(2 - 3*I)/2 + fresnelc(2 + 3*I)/2,
-I*(fresnelc(2 + 3*I) - fresnelc(2 - 3*I))/2
)
assert expand_func(integrate(fresnelc(z), z)) == \
z*fresnelc(z) - sin(pi*z**2/2)/pi
assert fresnelc(z).rewrite(meijerg) == sqrt(2)*pi*z**Rational(3, 4) * \
meijerg(((), (1,)), ((Rational(1, 4),),
(Rational(3, 4), 0)), -pi**2*z**4/16)/(2*(-z)**Rational(1, 4)*(z**2)**Rational(1, 4))
from sympy.testing.randtest import verify_numerically
verify_numerically(re(fresnels(z)), fresnels(z).as_real_imag()[0], z)
verify_numerically(im(fresnels(z)), fresnels(z).as_real_imag()[1], z)
verify_numerically(fresnels(z), fresnels(z).rewrite(hyper), z)
verify_numerically(fresnels(z), fresnels(z).rewrite(meijerg), z)
verify_numerically(re(fresnelc(z)), fresnelc(z).as_real_imag()[0], z)
verify_numerically(im(fresnelc(z)), fresnelc(z).as_real_imag()[1], z)
verify_numerically(fresnelc(z), fresnelc(z).rewrite(hyper), z)
verify_numerically(fresnelc(z), fresnelc(z).rewrite(meijerg), z)
raises(ArgumentIndexError, lambda: fresnels(z).fdiff(2))
raises(ArgumentIndexError, lambda: fresnelc(z).fdiff(2))
assert fresnels(x).taylor_term(-1, x) is S.Zero
assert fresnelc(x).taylor_term(-1, x) is S.Zero
assert fresnelc(x).taylor_term(1, x) == -pi**2*x**5/40
@slow
def test_fresnel_series():
assert fresnelc(z).series(z, n=15) == \
z - pi**2*z**5/40 + pi**4*z**9/3456 - pi**6*z**13/599040 + O(z**15)
# issues 6510, 10102
fs = (S.Half - sin(pi*z**2/2)/(pi**2*z**3)
+ (-1/(pi*z) + 3/(pi**3*z**5))*cos(pi*z**2/2))
fc = (S.Half - cos(pi*z**2/2)/(pi**2*z**3)
+ (1/(pi*z) - 3/(pi**3*z**5))*sin(pi*z**2/2))
assert fresnels(z).series(z, oo) == fs + O(z**(-6), (z, oo))
assert fresnelc(z).series(z, oo) == fc + O(z**(-6), (z, oo))
assert (fresnels(z).series(z, -oo) + fs.subs(z, -z)).expand().is_Order
assert (fresnelc(z).series(z, -oo) + fc.subs(z, -z)).expand().is_Order
assert (fresnels(1/z).series(z) - fs.subs(z, 1/z)).expand().is_Order
assert (fresnelc(1/z).series(z) - fc.subs(z, 1/z)).expand().is_Order
assert ((2*fresnels(3*z)).series(z, oo) - 2*fs.subs(z, 3*z)).expand().is_Order
assert ((3*fresnelc(2*z)).series(z, oo) - 3*fc.subs(z, 2*z)).expand().is_Order
|
3c85f0c2f465c84e13a0dc255e9810cb4ac7b1aea289bb66e8450fb5c9518d65 | 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.ode.odesimp` - Does all forms of ODE
simplification.
- :py:meth:`~sympy.solvers.ode.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.ode.constant_renumber` - Renumber arbitrary
constants.
- :py:meth:`~sympy.solvers.ode.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.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.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
:obj:`~sympy.solvers.ode.single.HomogeneousCoeffBest`, 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. 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:obj:`~.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.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.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.ode.odesimp` for it. For
example, solutions returned from the ``1st_homogeneous_coeff`` hints often
have many :obj:`~sympy.functions.elementary.exponential.log` terms, so
:py:meth:`~sympy.solvers.ode.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.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 sympy.core import Add, S, Mul, Pow, oo
from sympy.core.compatibility import ordered, iterable
from sympy.core.containers import Tuple
from sympy.core.expr import AtomicExpr, Expr
from sympy.core.function import (Function, Derivative, AppliedUndef, diff,
expand, expand_mul, Subs)
from sympy.core.multidimensional import vectorize
from sympy.core.numbers import NaN, zoo, 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, BooleanTrue,
BooleanFalse)
from sympy.functions import exp, log, sqrt
from sympy.functions.combinatorial.factorials import factorial
from sympy.integrals.integrals import Integral
from sympy.polys import (Poly, terms_gcd, PolynomialError, lcm)
from sympy.polys.polytools import cancel
from sympy.series import Order
from sympy.series.series import series
from sympy.simplify import (collect, logcombine, powsimp, # type: ignore
separatevars, simplify, cse)
from sympy.simplify.radsimp import collect_const
from sympy.solvers import checksol, solve
from sympy.utilities import numbered_symbols, default_sort_key, sift
from sympy.utilities.iterables import uniq
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 = (
"factorable",
"nth_algebraic",
"separable",
"1st_exact",
"1st_linear",
"Bernoulli",
"1st_rational_riccati",
"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_linear_airy",
"2nd_linear_bessel",
"2nd_hypergeometric",
"2nd_hypergeometric_Integral",
"nth_order_reducible",
"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",
"2nd_nonlinear_autonomous_conserved",
"2nd_nonlinear_autonomous_conserved_Integral",
)
def get_numbered_constants(eq, num=1, start=1, prefix='C'):
"""
Returns a list of constants that do not occur
in eq already.
"""
ncs = iter_numbered_constants(eq, start, prefix)
Cs = [next(ncs) for i in range(num)]
return (Cs[0] if num == 1 else tuple(Cs))
def iter_numbered_constants(eq, start=1, prefix='C'):
"""
Returns an iterator of constants that do not occur
in eq already.
"""
if isinstance(eq, (Expr, Eq)):
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}
return numbered_symbols(start=start, prefix=prefix, exclude=atom_set)
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.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):
from sympy.solvers.ode.systems import dsolve_system
# This may have to be changed in future
# when we have weakly and strongly
# connected components. This have to
# changed to show the systems that haven't
# been solved.
try:
sol = dsolve_system(eq, funcs=func, ics=ics, doit=True)
return sol[0] if len(sol) == 1 else sol
except NotImplementedError:
pass
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:
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, hint='all')
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
func = r['func']
order = r['order']
match = r[hint]
if isinstance(match, SingleODESolver):
solvefunc = match
elif hint.endswith('_Integral'):
solvefunc = globals()['ode_' + hint[:-len('_Integral')]]
else:
solvefunc = globals()['ode_' + 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
if isinstance(solvefunc, SingleODESolver):
sols = solvefunc.get_general_solution()
else:
sols = solvefunc(eq, func, order, match)
if iterable(sols):
rv = [odesimp(eq, s, func, hint) for s in sols]
else:
rv = odesimp(eq, sols, func, hint)
else:
# We still want to integrate (you can disable it separately with the hint)
if isinstance(solvefunc, SingleODESolver):
exprs = solvefunc.get_general_solution(simplify=False)
else:
match['simplify'] = False # Some hints can take advantage of this option
exprs = solvefunc(eq, func, order, match)
if isinstance(exprs, list):
rv = [_handle_Integral(expr, func, hint) for expr in exprs]
else:
rv = _handle_Integral(exprs, func, hint)
if isinstance(rv, list):
if simplify:
rv = _remove_redundant_solutions(eq, rv, order, func.args[0])
if len(rv) == 1:
rv = rv[0]
if ics and not 'power_series' in hint:
if isinstance(rv, (Expr, Eq)):
solved_constants = solve_ics([rv], [r['func']], cons(rv), ics)
rv = rv.subs(solved_constants)
else:
rv1 = []
for s in rv:
try:
solved_constants = solve_ics([s], [r['func']], cons(s), ics)
except ValueError:
continue
rv1.append(s.subs(solved_constants))
if len(rv1) == 1:
return rv1[0]
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.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)
# This check is necessary because of issue #15724
if not isinstance(sol2, BooleanAtom) or not subs_sols:
subs_sols = [s for s in subs_sols if not isinstance(s, BooleanAtom)]
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 ValueError("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")
return solved_constants[0]
def classify_ode(eq, func=None, dict=False, ics=None, *, prep=True, xi=None, eta=None, n=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:`~.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:func:`~sympy.integrals.integrals.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.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_exact',
'1st_linear',
'Bernoulli',
'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_exact_Integral',
'1st_linear_Integral', 'Bernoulli_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)
if func and len(func.args) != 1:
raise ValueError("dsolve() and classify_ode() only "
"work with functions of one variable, not %s" % func)
if isinstance(eq, Equality):
eq = eq.lhs - eq.rhs
# Some methods want the unprocessed equation
eq_orig = eq
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')
terms = n
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}
df = f(x).diff(x)
a = Wild('a', exclude=[f(x)])
d = Wild('d', exclude=[df, f(x).diff(x, 2)])
e = Wild('e', exclude=[df])
n = Wild('n', exclude=[x, f(x), df])
c1 = Wild('c1', exclude=[x])
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)])
boundary = {} # Used to extract initial conditions
C1 = Symbol("C1")
# 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}")
ode = SingleODEProblem(eq_orig, func, x, prep=prep, xi=xi, eta=eta)
user_hint = kwargs.get('hint', 'default')
# Used when dsolve is called without an explicit hint.
# We exit early to return the first valid match
early_exit = (user_hint=='default')
if user_hint.endswith('_Integral'):
user_hint = user_hint[:-len('_Integral')]
user_map = solver_map
# An explicit hint has been given to dsolve
# Skip matching code for other hints
if user_hint not in ['default', 'all', 'all_Integral', 'best'] and user_hint in solver_map:
user_map = {user_hint: solver_map[user_hint]}
for hint in user_map:
solver = user_map[hint](ode)
if solver.matches():
matching_hints[hint] = solver
if user_map[hint].has_integral:
matching_hints[hint + "_Integral"] = solver
if dict and early_exit:
matching_hints["default"] = hint
return matching_hints
eq = expand(eq)
# 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:
# 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
elif order == 2:
# Homogeneous second order differential equation of the form
# a3*f(x).diff(x, 2) + b3*f(x).diff(x) + c3
# 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:
if not all([r[key].is_polynomial() for key in r]):
n, d = reduced_eq.as_numer_denom()
reduced_eq = expand(n)
r = collect(reduced_eq,
[f(x).diff(x, 2), f(x).diff(x), f(x)]).match(deq)
if r and r[a3] != 0:
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, NaN, zoo, -oo):
check = q.subs(x, point)
if not check.has(oo, NaN, zoo, -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, NaN, zoo, -oo):
q = cancel(((x - point)**2)*q)
check = q.subs(x, point)
if not check.has(oo, NaN, zoo, -oo):
coeff_dict = {'p': p, 'q': q, 'x0': point, 'terms': terms}
matching_hints["2nd_power_series_regular"] = coeff_dict
# 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.
Some 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 or Matrix) 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. The value of this parameter can also be a Matrix if the system of ODEs are
linear first order of the form X' = AX where X is the vector of dependent variables.
Here, this function returns the coefficient matrix A.
'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.
'is_constant' (boolean), which tells if the system of ODEs is constant coefficient
or not. This key is temporary addition for now and is in the match dict only when
the system of ODEs is linear first order constant coefficient homogeneous. So, this
key's value is True for now if it is available else it doesn't exist.
'is_homogeneous' (boolean), which tells if the system of ODEs is homogeneous. Like the
key 'is_constant', this key is a temporary addition and it is True since this key value
is available only when the system is linear first order constant coefficient homogeneous.
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.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(x1, 12*x(t) - 6*y(t)), Eq(y1, 11*x(t) + 3*y(t)))
>>> classify_sysode(eq)
{'eq': [-12*x(t) + 6*y(t) + Derivative(x(t), t), -11*x(t) - 3*y(t) + Derivative(y(t), t)], 'func': [x(t), y(t)],
'func_coeff': {(0, x(t), 0): -12, (0, x(t), 1): 1, (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): 1}, 'is_linear': True, 'no_of_equation': 2, 'order': {x(t): 1, y(t): 1}, 'type_of_equation': None}
>>> eq = (Eq(diff(x(t),t), 5*t*x(t) + t**2*y(t) + 2), 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) - 2, 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': None}
"""
# 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
t = list(list(eq[0].atoms(Derivative))[0].atoms(Symbol))[0]
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")
# find all the functions if not given
order = dict()
if funcs==[None]:
funcs = _extract_funcs(eq)
funcs = list(set(funcs))
if len(funcs) != len(eq):
raise ValueError("Number of functions given is not equal to the number of equations %s" % funcs)
# This logic of list of lists in funcs to
# be replaced later.
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:
func_dict[eq_no] = [func_dict[eq_no], 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)
else:
type_of_equation = None
# If the equation doesn't match up with any of the
# general case solvers in systems.py and the number
# of equations is greater than 2, then NotImplementedError
# should be raised.
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.Zero,S.Zero]
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:
return None
else:
if all(not r[k].has(t) for k in 'a1 a2 b1 b2 c1 c2'.split()):
return None
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 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_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
@vectorize(0)
def odesimp(ode, eq, func, hint):
r"""
Simplifies solutions of 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.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.ode.odesimp`, but the individual hint functions
do not call :py:meth:`~sympy.solvers.ode.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.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 \
| -|u1 + -------|
| | /1 \|
| | sin|--||
| \ \u1//
log(f(x)) = log(C1) + | ---------------- d(u1)
| 2
| u1
|
/
>>> 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)
constants = eq.free_symbols - ode.free_symbols
# First, integrate if the hint allows it.
eq = _handle_Integral(eq, func, 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]
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], ode.free_symbols)
# If there is only 1 solution, return it;
# otherwise return the list of solutions.
if len(eq) == 1:
eq = eq[0]
return eq
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.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`` |
| :obj:`~sympy.integrals.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, Integral
>>> from sympy.solvers.ode.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 _extract_funcs(eqs):
from sympy.core.basic import preorder_traversal
funcs = []
for eq in eqs:
derivs = [node for node in preorder_traversal(eq) if isinstance(node, Derivative)]
func = []
for d in derivs:
func += list(d.atoms(AppliedUndef))
for func_ in func:
funcs.append(func_)
funcs = list(uniq(funcs))
return funcs
def _get_constant_subexpressions(expr, Cs):
Cs = set(Cs)
Ces = []
def _recursive_walk(expr):
expr_syms = expr.free_symbols
if expr_syms 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.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.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 IndexError:
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, variables=None, newconstants=None):
r"""
Renumber arbitrary constants in ``expr`` to use the symbol names as given
in ``newconstants``. In the process, this reorders expression terms in a
standard way.
If ``newconstants`` is not provided then the new constant names will be
``C1``, ``C2`` etc. Otherwise ``newconstants`` should be an iterable
giving the new symbols to use for the constants in order.
The ``variables`` argument is a list of non-constant symbols. All other
free symbols found in ``expr`` are assumed to be constants and will be
renumbered. If ``variables`` is not given then any numbered symbol
beginning with ``C`` (e.g. ``C1``) is assumed to be a constant.
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
>>> from sympy.solvers.ode.ode import constant_renumber
>>> x, C1, C2, C3 = symbols('x,C1:4')
>>> expr = C3 + C2*x + C1*x**2
>>> expr
C1*x**2 + C2*x + C3
>>> constant_renumber(expr)
C1 + C2*x + C3*x**2
The ``variables`` argument specifies which are constants so that the
other symbols will not be renumbered:
>>> constant_renumber(expr, [C1, x])
C1*x**2 + C2 + C3*x
The ``newconstants`` argument is used to specify what symbols to use when
replacing the constants:
>>> constant_renumber(expr, [x], newconstants=symbols('E1:4'))
E1 + E2*x + E3*x**2
"""
# System of expressions
if isinstance(expr, (set, list, tuple)):
return type(expr)(constant_renumber(Tuple(*expr),
variables=variables, newconstants=newconstants))
# Symbols in solution but not ODE are constants
if variables is not None:
variables = set(variables)
free_symbols = expr.free_symbols
constantsymbols = list(free_symbols - variables)
# Any Cn is a constant...
else:
variables = set()
isconstant = lambda s: s.startswith('C') and s[1:].isdigit()
constantsymbols = [sym for sym in expr.free_symbols if isconstant(sym.name)]
# Find new constants checking that they aren't already in the ODE
if newconstants is None:
iter_constants = numbered_symbols(start=1, prefix='C', exclude=variables)
else:
iter_constants = (sym for sym in newconstants if sym not in variables)
constants_found = []
# 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
"""
# For system of expressions
if isinstance(expr, Tuple):
renumbered = [_constant_renumber(e) for e in expr]
return Tuple(*renumbered)
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.append(expr)
return expr
elif expr.is_Function or expr.is_Pow:
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)
# Don't renumber symbols present in the ODE.
constants_found = [c for c in constants_found if c not in variables]
# Renumbering happens here
subs_dict = {var: cons for var, cons in zip(constants_found, iter_constants)}
expr = expr.subs(subs_dict, simultaneous=True)
return expr
def _handle_Integral(expr, func, hint):
r"""
Converts a solution with Integrals in it into an actual solution.
For most hints, this simply runs ``expr.doit()``.
"""
if hint == "nth_linear_constant_coeff_homogeneous":
sol = expr
elif not hint.endswith("_Integral"):
sol = expr.doit()
else:
sol = expr
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
:obj:`~sympy.solvers.ode.single.HomogeneousCoeffSubsDepDivIndep` and
:obj:`~sympy.solvers.ode.single.HomogeneousCoeffSubsIndepDivDep`).
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_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 homogeneous
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
>>> 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.Zero
# Stripping of terms so that the sum starts with the same number.
teq = S.Zero
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
homogeneous 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
>>> f = Function("f")
>>> eq = x*(f(x).diff(x, 2)) + 2*(f(x).diff(x)) + x*f(x)
>>> pprint(dsolve(eq, hint='2nd_power_series_regular'))
/ 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)
m = Dummy("m") # for solving the indicial equation
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, x=x, n=1, x0=x0)
if isinstance(term, Order):
indicial.append(S.Zero)
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.Zero
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)]
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.Zero
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.Zero
else:
frobdict[numsyms[i]] = -num/(indicial.subs(d, m+i))
return frobdict
def _remove_redundant_solutions(eq, solns, order, var):
r"""
Remove redundant solutions from the set of solutions.
This function is needed because otherwise dsolve can return
redundant solutions. As an example consider:
eq = Eq((f(x).diff(x, 2))*f(x).diff(x), 0)
There are two ways to find solutions to eq. The first is to solve f(x).diff(x, 2) = 0
leading to solution f(x)=C1 + C2*x. 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 second solution is a special case of the first and we don't
want to return it.
This does not always happen. If we have
eq = Eq((f(x)**2-4)*(f(x).diff(x)-4), 0)
then we get the algebraic solution f(x) = [-2, 2] 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 _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 _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 dsolve may be given explicitly or implicitly.
# We will equate the sol1=(soln1.rhs - soln1.lhs), sol2=(soln2.rhs - soln2.lhs)
# of the two solutions.
#
# Since this is supposed to hold for all x it also holds for derivatives.
# 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 sol2. If we can find a solution that doesn't depend on x then it
# means that some value of the constants in sol1 is a special case of
# sol2 corresponding to a particular choice of the integration constants.
# In case the solution is in implicit form we subtract the sides
soln1 = soln1.rhs - soln1.lhs
soln2 = soln2.rhs - soln2.lhs
# Work for the series solution
if soln1.has(Order) and soln2.has(Order):
if soln1.getO() == soln2.getO():
soln1 = soln1.removeO()
soln2 = soln2.removeO()
else:
return False
elif soln1.has(Order) or soln2.has(Order):
return False
constants1 = soln1.free_symbols.difference(eq.free_symbols)
constants2 = soln2.free_symbols.difference(eq.free_symbols)
constants1_new = get_numbered_constants(Tuple(soln1, soln2), 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 sol1 = sol2, sol1'=sol2', ...
lhs = soln1
rhs = soln2
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)]
try:
constant_solns = solve(eqns, constants2)
except NotImplementedError:
return False
# Sometimes returns a dict and sometimes a list of dicts
if isinstance(constant_solns, dict):
constant_solns = [constant_solns]
# after solving the issue 17418, maybe we don't need the following checksol code.
for constant_soln in constant_solns:
for eq in eqns:
eq=eq.rhs-eq.lhs
if checksol(eq, constant_soln) is not True:
return False
# 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
return False
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, pprint, exp
>>> from sympy.solvers.ode.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 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 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']
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.Zero,S.Zero]
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'] == '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_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_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))
if isinstance(sol2r, Equality):
sol2r = [sol2r]
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']
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')
fu, fv, fw = symbols('u, v, w', cls=Function)
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(fv(u),u) - ((a*F3-c*F1)/(c*F2-b*F3)).subs(w,z_xy).subs(v,fv(u))).rhs
z_x = dsolve(diff(fw(u),u) - ((b*F1-a*F2)/(c*F2-b*F3)).subs(v,y_zx).subs(w,fw(u))).rhs
z_y = dsolve(diff(fw(v),v) - ((b*F1-a*F2)/(a*F3-c*F1)).subs(u,x_yz).subs(w,fw(v))).rhs
x_y = dsolve(diff(fu(v),v) - ((c*F2-b*F3)/(a*F3-c*F1)).subs(w,z_xy).subs(u,fu(v))).rhs
y_z = dsolve(diff(fv(w),w) - ((a*F3-c*F1)/(b*F1-a*F2)).subs(u,x_yz).subs(v,fv(w))).rhs
x_z = dsolve(diff(fu(w),w) - ((c*F2-b*F3)/(b*F1-a*F2)).subs(v,y_zx).subs(u,fu(w))).rhs
sol1 = dsolve(diff(fu(t),t) - (c*F2 - b*F3).subs(v,y_x).subs(w,z_x).subs(u,fu(t))).rhs
sol2 = dsolve(diff(fv(t),t) - (a*F3 - c*F1).subs(u,x_y).subs(w,z_y).subs(v,fv(t))).rhs
sol3 = dsolve(diff(fw(t),t) - (b*F1 - a*F2).subs(u,x_z).subs(v,y_z).subs(w,fw(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, z, 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')
fu, fv, fw = symbols('u, v, w', cls=Function)
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 + x(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(y(t)*(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)
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(fv(u), u) - ((v*(a*F3 - c*F1))/(u*(c*F2 - b*F3))).subs(w, z_xy).subs(v, fv(u))).rhs
z_x = dsolve(diff(fw(u), u) - ((w*(b*F1 - a*F2))/(u*(c*F2 - b*F3))).subs(v, y_zx).subs(w, fw(u))).rhs
z_y = dsolve(diff(fw(v), v) - ((w*(b*F1 - a*F2))/(v*(a*F3 - c*F1))).subs(u, x_yz).subs(w, fw(v))).rhs
x_y = dsolve(diff(fu(v), v) - ((u*(c*F2 - b*F3))/(v*(a*F3 - c*F1))).subs(w, z_xy).subs(u, fu(v))).rhs
y_z = dsolve(diff(fv(w), w) - ((v*(a*F3 - c*F1))/(w*(b*F1 - a*F2))).subs(u, x_yz).subs(v, fv(w))).rhs
x_z = dsolve(diff(fu(w), w) - ((u*(c*F2 - b*F3))/(w*(b*F1 - a*F2))).subs(v, y_zx).subs(u, fu(w))).rhs
sol1 = dsolve(diff(fu(t), t) - (u*(c*F2 - b*F3)).subs(v, y_x).subs(w, z_x).subs(u, fu(t))).rhs
sol2 = dsolve(diff(fv(t), t) - (v*(a*F3 - c*F1)).subs(u, x_y).subs(w, z_y).subs(v, fv(t))).rhs
sol3 = dsolve(diff(fw(t), t) - (w*(b*F1 - a*F2)).subs(u, x_z).subs(v, y_z).subs(w, fw(t))).rhs
return [sol1, sol2, sol3]
#This import is written at the bottom to avoid circular imports.
from .single import SingleODEProblem, SingleODESolver, solver_map
|
9d5c19ff92ae8a0a734c016d4325a0ba15b69ad6fe80b597a7ef1f6a480eb876 | #
# This is the module for ODE solver classes for single ODEs.
#
import typing
if typing.TYPE_CHECKING:
from typing import ClassVar
from typing import Dict, Type, Iterator, List, Optional
from .riccati import match_riccati, solve_riccati
from sympy.core import Add, S, Pow, Rational
from sympy.core.exprtools import factor_terms
from sympy.core.expr import Expr
from sympy.core.function import AppliedUndef, Derivative, diff, Function, expand, Subs, _mexpand
from sympy.core.numbers import Float, zoo
from sympy.core.relational import Equality, Eq
from sympy.core.symbol import Symbol, Dummy, Wild
from sympy.core.mul import Mul
from sympy.functions import exp, tan, log, sqrt, besselj, bessely, cbrt, airyai, airybi
from sympy.integrals import Integral
from sympy.polys import Poly
from sympy.polys.polytools import cancel, factor, degree
from sympy.simplify import collect, simplify, separatevars, logcombine, posify
from sympy.simplify.radsimp import fraction
from sympy.utilities import numbered_symbols
from sympy.solvers.solvers import solve
from sympy.solvers.deutils import ode_order, _preprocess
from sympy.polys.matrices.linsolve import _lin_eq2dict
from sympy.polys.solvers import PolyNonlinearError
from .hypergeometric import equivalence_hypergeometric, match_2nd_2F1_hypergeometric, \
get_sol_2F1_hypergeometric, match_2nd_hypergeometric
from .nonhomogeneous import _get_euler_characteristic_eq_sols, _get_const_characteristic_eq_sols, \
_solve_undetermined_coefficients, _solve_variation_of_parameters, _test_term, _undetermined_coefficients_match, \
_get_simplified_sol
from .lie_group import _ode_lie_group
class ODEMatchError(NotImplementedError):
"""Raised if a SingleODESolver is asked to solve an ODE it does not match"""
pass
def cached_property(func):
'''Decorator to cache property method'''
attrname = '_' + func.__name__
def propfunc(self):
val = getattr(self, attrname, None)
if val is None:
val = func(self)
setattr(self, attrname, val)
return val
return property(propfunc)
class SingleODEProblem:
"""Represents an ordinary differential equation (ODE)
This class is used internally in the by dsolve and related
functions/classes so that properties of an ODE can be computed
efficiently.
Examples
========
This class is used internally by dsolve. To instantiate an instance
directly first define an ODE problem:
>>> from sympy import Function, Symbol
>>> x = Symbol('x')
>>> f = Function('f')
>>> eq = f(x).diff(x, 2)
Now you can create a SingleODEProblem instance and query its properties:
>>> from sympy.solvers.ode.single import SingleODEProblem
>>> problem = SingleODEProblem(f(x).diff(x), f(x), x)
>>> problem.eq
Derivative(f(x), x)
>>> problem.func
f(x)
>>> problem.sym
x
"""
# Instance attributes:
eq = None # type: Expr
func = None # type: AppliedUndef
sym = None # type: Symbol
_order = None # type: int
_eq_expanded = None # type: Expr
_eq_preprocessed = None # type: Expr
_eq_high_order_free = None
def __init__(self, eq, func, sym, prep=True, **kwargs):
assert isinstance(eq, Expr)
assert isinstance(func, AppliedUndef)
assert isinstance(sym, Symbol)
assert isinstance(prep, bool)
self.eq = eq
self.func = func
self.sym = sym
self.prep = prep
self.params = kwargs
@cached_property
def order(self) -> int:
return ode_order(self.eq, self.func)
@cached_property
def eq_preprocessed(self) -> Expr:
return self._get_eq_preprocessed()
@cached_property
def eq_high_order_free(self) -> Expr:
a = Wild('a', exclude=[self.func])
c1 = Wild('c1', exclude=[self.sym])
# Precondition to try remove f(x) from highest order derivative
reduced_eq = None
if self.eq.is_Add:
deriv_coef = self.eq.coeff(self.func.diff(self.sym, self.order))
if deriv_coef not in (1, 0):
r = deriv_coef.match(a*self.func**c1)
if r and r[c1]:
den = self.func**r[c1]
reduced_eq = Add(*[arg/den for arg in self.eq.args])
if not reduced_eq:
reduced_eq = expand(self.eq)
return reduced_eq
@cached_property
def eq_expanded(self) -> Expr:
return expand(self.eq_preprocessed)
def _get_eq_preprocessed(self) -> Expr:
if self.prep:
process_eq, process_func = _preprocess(self.eq, self.func)
if process_func != self.func:
raise ValueError
else:
process_eq = self.eq
return process_eq
def get_numbered_constants(self, num=1, start=1, prefix='C') -> List[Symbol]:
"""
Returns a list of constants that do not occur
in eq already.
"""
ncs = self.iter_numbered_constants(start, prefix)
Cs = [next(ncs) for i in range(num)]
return Cs
def iter_numbered_constants(self, start=1, prefix='C') -> Iterator[Symbol]:
"""
Returns an iterator of constants that do not occur
in eq already.
"""
atom_set = self.eq.free_symbols
func_set = self.eq.atoms(Function)
if func_set:
atom_set |= {Symbol(str(f.func)) for f in func_set}
return numbered_symbols(start=start, prefix=prefix, exclude=atom_set)
@cached_property
def is_autonomous(self):
u = Dummy('u')
x = self.sym
syms = self.eq.subs(self.func, u).free_symbols
return x not in syms
def get_linear_coefficients(self, 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.single import SingleODEProblem
>>> f = Function('f')
>>> eq = 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)
>>> obj = SingleODEProblem(eq, f(x), x)
>>> obj.get_linear_coefficients(eq, f(x), 3)
{-1: x - sin(x), 0: -1, 1: cos(x) + 2, 2: x, 3: 1}
>>> eq = 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))
>>> obj = SingleODEProblem(eq, f(x), x)
>>> obj.get_linear_coefficients(eq, f(x), 3) == None
True
"""
f = func.func
x = func.args[0]
symset = {Derivative(f(x), x, i) for i in range(order+1)}
try:
rhs, lhs_terms = _lin_eq2dict(eq, symset)
except PolyNonlinearError:
return None
if rhs.has(func) or any(c.has(func) for c in lhs_terms.values()):
return None
terms = {i: lhs_terms.get(f(x).diff(x, i), S.Zero) for i in range(order+1)}
terms[-1] = rhs
return terms
# TODO: Add methods that can be used by many ODE solvers:
# order
# is_linear()
# get_linear_coefficients()
# eq_prepared (the ODE in prepared form)
class SingleODESolver:
"""
Base class for Single ODE solvers.
Subclasses should implement the _matches and _get_general_solution
methods. This class is not intended to be instantiated directly but its
subclasses are as part of dsolve.
Examples
========
You can use a subclass of SingleODEProblem to solve a particular type of
ODE. We first define a particular ODE problem:
>>> from sympy import Function, Symbol
>>> x = Symbol('x')
>>> f = Function('f')
>>> eq = f(x).diff(x, 2)
Now we solve this problem using the NthAlgebraic solver which is a
subclass of SingleODESolver:
>>> from sympy.solvers.ode.single import NthAlgebraic, SingleODEProblem
>>> problem = SingleODEProblem(eq, f(x), x)
>>> solver = NthAlgebraic(problem)
>>> solver.get_general_solution()
[Eq(f(x), _C*x + _C)]
The normal way to solve an ODE is to use dsolve (which would use
NthAlgebraic and other solvers internally). When using dsolve a number of
other things are done such as evaluating integrals, simplifying the
solution and renumbering the constants:
>>> from sympy import dsolve
>>> dsolve(eq, hint='nth_algebraic')
Eq(f(x), C1 + C2*x)
"""
# Subclasses should store the hint name (the argument to dsolve) in this
# attribute
hint = None # type: ClassVar[str]
# Subclasses should define this to indicate if they support an _Integral
# hint.
has_integral = None # type: ClassVar[bool]
# The ODE to be solved
ode_problem = None # type: SingleODEProblem
# Cache whether or not the equation has matched the method
_matched = None # type: Optional[bool]
# Subclasses should store in this attribute the list of order(s) of ODE
# that subclass can solve or leave it to None if not specific to any order
order = None # type: Optional[list]
def __init__(self, ode_problem):
self.ode_problem = ode_problem
def matches(self) -> bool:
if self.order is not None and self.ode_problem.order not in self.order:
self._matched = False
return self._matched
if self._matched is None:
self._matched = self._matches()
return self._matched
def get_general_solution(self, *, simplify: bool = True) -> List[Equality]:
if not self.matches():
msg = "%s solver can not solve:\n%s"
raise ODEMatchError(msg % (self.hint, self.ode_problem.eq))
return self._get_general_solution(simplify_flag=simplify)
def _matches(self) -> bool:
msg = "Subclasses of SingleODESolver should implement matches."
raise NotImplementedError(msg)
def _get_general_solution(self, *, simplify_flag: bool = True) -> List[Equality]:
msg = "Subclasses of SingleODESolver should implement get_general_solution."
raise NotImplementedError(msg)
class SinglePatternODESolver(SingleODESolver):
'''Superclass for ODE solvers based on pattern matching'''
def wilds(self):
prob = self.ode_problem
f = prob.func.func
x = prob.sym
order = prob.order
return self._wilds(f, x, order)
def wilds_match(self):
match = self._wilds_match
return [match.get(w, S.Zero) for w in self.wilds()]
def _matches(self):
eq = self.ode_problem.eq_expanded
f = self.ode_problem.func.func
x = self.ode_problem.sym
order = self.ode_problem.order
df = f(x).diff(x, order)
if order not in [1, 2]:
return False
pattern = self._equation(f(x), x, order)
if not pattern.coeff(df).has(Wild):
eq = expand(eq / eq.coeff(df))
eq = eq.collect([f(x).diff(x), f(x)], func = cancel)
self._wilds_match = match = eq.match(pattern)
if match is not None:
return self._verify(f(x))
return False
def _verify(self, fx) -> bool:
return True
def _wilds(self, f, x, order):
msg = "Subclasses of SingleODESolver should implement _wilds"
raise NotImplementedError(msg)
def _equation(self, fx, x, order):
msg = "Subclasses of SingleODESolver should implement _equation"
raise NotImplementedError(msg)
class NthAlgebraic(SingleODESolver):
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')
[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).
"""
hint = 'nth_algebraic'
has_integral = True # nth_algebraic_Integral hint
def _matches(self):
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).
"""
eq = self.ode_problem.eq
func = self.ode_problem.func
var = self.ode_problem.sym
# Derivative that solve can handle:
diffx = self._get_diffx(var)
# 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))
subs_eqn = replace(eq, var)
try:
# turn off simplification to protect Integrals that have
# _t instead of fx in them and would otherwise factor
# as t_*Integral(1, x)
solns = solve(subs_eqn, func, simplify=False)
except NotImplementedError:
solns = []
solns = [simplify(unreplace(soln, var)) for soln in solns]
solns = [Equality(func, soln) for soln in solns]
self.solutions = solns
return len(solns) != 0
def _get_general_solution(self, *, simplify_flag: bool = True):
return self.solutions
# This needs to produce an invertible function but the inverse depends
# which variable we are integrating with respect to. Since the class can
# be stored in cached results we need to ensure that we always get the
# same class back for each particular integration variable so we store these
# classes in a global dict:
_diffx_stored = {} # type: Dict[Symbol, Type[Function]]
@staticmethod
def _get_diffx(var):
diffcls = NthAlgebraic._diffx_stored.get(var, None)
if diffcls is None:
# A class that behaves like Derivative wrt var but is "invertible".
class diffx(Function):
def inverse(self):
# don't use integrate here because fx has been replaced by _t
# in the equation; integrals will not be correct while solve
# is at work.
return lambda expr: Integral(expr, var) + Dummy('C')
diffcls = NthAlgebraic._diffx_stored.setdefault(var, diffx)
return diffcls
class FirstExact(SinglePatternODESolver):
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
"""
hint = "1st_exact"
has_integral = True
order = [1]
def _wilds(self, f, x, order):
P = Wild('P', exclude=[f(x).diff(x)])
Q = Wild('Q', exclude=[f(x).diff(x)])
return P, Q
def _equation(self, fx, x, order):
P, Q = self.wilds()
return P + Q*fx.diff(x)
def _verify(self, fx) -> bool:
P, Q = self.wilds()
x = self.ode_problem.sym
y = Dummy('y')
m, n = self.wilds_match()
m = m.subs(fx, y)
n = n.subs(fx, y)
numerator = cancel(m.diff(y) - n.diff(x))
if numerator.is_zero:
# Is exact
return True
else:
# The following few conditions try to convert a non-exact
# differential equation into an exact one.
# References:
# 1. Differential equations with applications
# and historical notes - George E. Simmons
# 2. https://math.okstate.edu/people/binegar/2233-S99/2233-l12.pdf
factor_n = cancel(numerator/n)
factor_m = cancel(-numerator/m)
if y not in factor_n.free_symbols:
# If (dP/dy - dQ/dx) / Q = f(x)
# then exp(integral(f(x))*equation becomes exact
factor = factor_n
integration_variable = x
elif x not in factor_m.free_symbols:
# If (dP/dy - dQ/dx) / -P = f(y)
# then exp(integral(f(y))*equation becomes exact
factor = factor_m
integration_variable = y
else:
# Couldn't convert to exact
return False
factor = exp(Integral(factor, integration_variable))
m *= factor
n *= factor
self._wilds_match[P] = m.subs(y, fx)
self._wilds_match[Q] = n.subs(y, fx)
return True
def _get_general_solution(self, *, simplify_flag: bool = True):
m, n = self.wilds_match()
fx = self.ode_problem.func
x = self.ode_problem.sym
(C1,) = self.ode_problem.get_numbered_constants(num=1)
y = Dummy('y')
m = m.subs(fx, y)
n = n.subs(fx, y)
gen_sol = Eq(Subs(Integral(m, x)
+ Integral(n - Integral(m, x).diff(y), y), y, fx), C1)
return [gen_sol]
class FirstLinear(SinglePatternODESolver):
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
"""
hint = '1st_linear'
has_integral = True
order = [1]
def _wilds(self, f, x, order):
P = Wild('P', exclude=[f(x)])
Q = Wild('Q', exclude=[f(x), f(x).diff(x)])
return P, Q
def _equation(self, fx, x, order):
P, Q = self.wilds()
return fx.diff(x) + P*fx - Q
def _get_general_solution(self, *, simplify_flag: bool = True):
P, Q = self.wilds_match()
fx = self.ode_problem.func
x = self.ode_problem.sym
(C1,) = self.ode_problem.get_numbered_constants(num=1)
gensol = Eq(fx, ((C1 + Integral(Q*exp(Integral(P, x)), x))
* exp(-Integral(P, x))))
return [gensol]
class AlmostLinear(SinglePatternODESolver):
r"""
Solves an almost-linear differential equation.
The general form of an almost linear differential equation is
.. math:: a(x) g'(f(x)) f'(x) + b(x) g(f(x)) + c(x)
Here `f(x)` is the function to be solved for (the dependent variable).
The substitution `g(f(x)) = u(x)` leads to a linear differential equation
for `u(x)` of the form `a(x) u' + b(x) u + c(x) = 0`. This can be solved
for `u(x)` by the `first_linear` hint and then `f(x)` is found by solving
`g(f(x)) = u(x)`.
See Also
========
:obj:`sympy.solvers.ode.single.FirstLinear`
Examples
========
>>> from sympy import Function, pprint, sin, cos
>>> from sympy.solvers.ode import dsolve
>>> 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
>>> example = cos(f(x))*f(x).diff(x) + sin(f(x)) + 1
>>> pprint(example)
d
sin(f(x)) + cos(f(x))*--(f(x)) + 1
dx
>>> pprint(dsolve(example, f(x), hint='almost_linear'))
/ -x \ / -x \
[f(x) = pi - asin\C1*e - 1/, f(x) = asin\C1*e - 1/]
References
==========
- Joel Moses, "Symbolic Integration - The Stormy Decade", Communications
of the ACM, Volume 14, Number 8, August 1971, pp. 558
"""
hint = "almost_linear"
has_integral = True
order = [1]
def _wilds(self, f, x, order):
P = Wild('P', exclude=[f(x).diff(x)])
Q = Wild('Q', exclude=[f(x).diff(x)])
return P, Q
def _equation(self, fx, x, order):
P, Q = self.wilds()
return P*fx.diff(x) + Q
def _verify(self, fx):
a, b = self.wilds_match()
c, b = b.as_independent(fx) if b.is_Add else (S.Zero, b)
# a, b and c are the function a(x), b(x) and c(x) respectively.
# c(x) is obtained by separating out b as terms with and without fx i.e, l(y)
# The following conditions checks if the given equation is an almost-linear differential equation using the fact that
# a(x)*(l(y))' / l(y)' is independent of l(y)
if b.diff(fx) != 0 and not simplify(b.diff(fx)/a).has(fx):
self.ly = factor_terms(b).as_independent(fx, as_Add=False)[1] # Gives the term containing fx i.e., l(y)
self.ax = a / self.ly.diff(fx)
self.cx = -c # cx is taken as -c(x) to simplify expression in the solution integral
self.bx = factor_terms(b) / self.ly
return True
return False
def _get_general_solution(self, *, simplify_flag: bool = True):
x = self.ode_problem.sym
(C1,) = self.ode_problem.get_numbered_constants(num=1)
gensol = Eq(self.ly, ((C1 + Integral((self.cx/self.ax)*exp(Integral(self.bx/self.ax, x)), x))
* exp(-Integral(self.bx/self.ax, x))))
return [gensol]
class Bernoulli(SinglePatternODESolver):
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
:obj:`~sympy.solvers.ode.single.FirstLinear`). 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'), num_columns=110)
-1
-----
n - 1
// / / \ \
|| | | | |
|| | / | / | / |
|| | | | | | | |
|| | (1 - n)* | P(x) dx | (1 - n)* | P(x) dx | (n - 1)* | P(x) dx|
|| | | | | | | |
|| | / | / | / |
f(x) = ||C1 - n* | Q(x)*e dx + | Q(x)*e dx|*e |
|| | | | |
\\ / / / /
Note that the equation is separable when `n = 1` (see the docstring of
:obj:`~sympy.solvers.ode.single.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) = -----------------
C1*x + log(x) + 1
References
==========
- https://en.wikipedia.org/wiki/Bernoulli_differential_equation
- M. Tenenbaum & H. Pollard, "Ordinary Differential Equations",
Dover 1963, pp. 95
# indirect doctest
"""
hint = "Bernoulli"
has_integral = True
order = [1]
def _wilds(self, f, x, order):
P = Wild('P', exclude=[f(x)])
Q = Wild('Q', exclude=[f(x)])
n = Wild('n', exclude=[x, f(x), f(x).diff(x)])
return P, Q, n
def _equation(self, fx, x, order):
P, Q, n = self.wilds()
return fx.diff(x) + P*fx - Q*fx**n
def _get_general_solution(self, *, simplify_flag: bool = True):
P, Q, n = self.wilds_match()
fx = self.ode_problem.func
x = self.ode_problem.sym
(C1,) = self.ode_problem.get_numbered_constants(num=1)
if n==1:
gensol = Eq(log(fx), (
C1 + Integral((-P + Q), x)
))
else:
gensol = Eq(fx**(1-n), (
(C1 - (n - 1) * Integral(Q*exp(-n*Integral(P, x))
* exp(Integral(P, x)), x)
) * exp(-(1 - n)*Integral(P, x)))
)
return [gensol]
class Factorable(SingleODESolver):
r"""
Solves equations having a solvable factor.
This function is used to solve the equation having factors. Factors may be of type algebraic or ode. It
will try to solve each factor independently. Factors will be solved by calling dsolve. We will return the
list of solutions.
Examples
========
>>> from sympy import Function, dsolve, pprint
>>> from sympy.abc import x
>>> f = Function('f')
>>> eq = (f(x)**2-4)*(f(x).diff(x)+f(x))
>>> pprint(dsolve(eq, f(x)))
-x
[f(x) = 2, f(x) = -2, f(x) = C1*e ]
"""
hint = "factorable"
has_integral = False
def _matches(self):
eq = self.ode_problem.eq
f = self.ode_problem.func.func
x = self.ode_problem.sym
order =self.ode_problem.order
df = f(x).diff(x)
self.eqs = []
eq = eq.collect(f(x), func = cancel)
eq = fraction(factor(eq))[0]
factors = Mul.make_args(factor(eq))
roots = [fac.as_base_exp() for fac in factors if len(fac.args)!=0]
if len(roots)>1 or roots[0][1]>1:
for base, expo in roots:
if base.has(f(x)):
self.eqs.append(base)
if len(self.eqs)>0:
return True
roots = solve(eq, df)
if len(roots)>0:
self.eqs = [(df - root) for root in roots]
if len(self.eqs)==1:
if order>1:
return False
if self.eqs[0].has(Float):
return False
return fraction(factor(self.eqs[0]))[0]-eq!=0
return True
for i in factors:
if i.has(f(x)):
self.eqs.append(i)
return len(self.eqs)>0 and len(factors)>1
def _get_general_solution(self, *, simplify_flag: bool = True):
func = self.ode_problem.func.func
x = self.ode_problem.sym
eqns = self.eqs
sols = []
for eq in eqns:
try:
sol = dsolve(eq, func(x))
except NotImplementedError:
continue
else:
if isinstance(sol, list):
sols.extend(sol)
else:
sols.append(sol)
if sols == []:
raise NotImplementedError("The given ODE " + str(eq) + " cannot be solved by"
+ " the factorable group method")
return sols
class RiccatiSpecial(SinglePatternODESolver):
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, 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, hint="Riccati_special_minus2")
>>> 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
==========
- http://www.maplesoft.com/support/help/Maple/view.aspx?path=odeadvisor/Riccati
- http://eqworld.ipmnet.ru/en/solutions/ode/ode0106.pdf -
http://eqworld.ipmnet.ru/en/solutions/ode/ode0123.pdf
"""
hint = "Riccati_special_minus2"
has_integral = False
order = [1]
def _wilds(self, f, x, order):
a = Wild('a', exclude=[x, f(x), f(x).diff(x), 0])
b = Wild('b', exclude=[x, f(x), f(x).diff(x), 0])
c = Wild('c', exclude=[x, f(x), f(x).diff(x)])
d = Wild('d', exclude=[x, f(x), f(x).diff(x)])
return a, b, c, d
def _equation(self, fx, x, order):
a, b, c, d = self.wilds()
return a*fx.diff(x) + b*fx**2 + c*fx/x + d/x**2
def _get_general_solution(self, *, simplify_flag: bool = True):
a, b, c, d = self.wilds_match()
fx = self.ode_problem.func
x = self.ode_problem.sym
(C1,) = self.ode_problem.get_numbered_constants(num=1)
mu = sqrt(4*d*b - (a - c)**2)
gensol = Eq(fx, (a - c - mu*tan(mu/(2*a)*log(x) + C1))/(2*b*x))
return [gensol]
class RationalRiccati(SinglePatternODESolver):
r"""
Gives general solutions to the first order Riccati differential
equations that have atleast one rational particular solution.
.. math :: y' = b_0(x) + b_1(x) y + b_2(x) y^2
where `b_0`, `b_1` and `b_2` are rational functions of `x`
with `b_2 \ne 0` (`b_2 = 0` would make it a Bernoulli equation).
Examples
========
>>> from sympy import Symbol, Function, dsolve, checkodesol
>>> f = Function('f')
>>> x = Symbol('x')
>>> eq = -x**4*f(x)**2 + x**3*f(x).diff(x) + x**2*f(x) + 20
>>> sol = dsolve(eq, hint="1st_rational_riccati")
>>> sol
Eq(f(x), (4*C1 - 5*x**9 - 4)/(x**2*(C1 + x**9 - 1)))
>>> checkodesol(eq, sol)
(True, 0)
References
==========
- Riccati ODE: https://en.wikipedia.org/wiki/Riccati_equation
- N. Thieu Vo - Rational and Algebraic Solutions of First-Order Algebraic ODEs:
Algorithm 11, pp. 78 - https://www3.risc.jku.at/publications/download/risc_5387/PhDThesisThieu.pdf
"""
has_integral = False
hint = "1st_rational_riccati"
order = [1]
def _wilds(self, f, x, order):
b0 = Wild('b0', exclude=[f(x), f(x).diff(x)])
b1 = Wild('b1', exclude=[f(x), f(x).diff(x)])
b2 = Wild('b2', exclude=[f(x), f(x).diff(x)])
return (b0, b1, b2)
def _equation(self, fx, x, order):
b0, b1, b2 = self.wilds()
return fx.diff(x) - b0 - b1*fx - b2*fx**2
def _matches(self):
eq = self.ode_problem.eq_expanded
f = self.ode_problem.func.func
x = self.ode_problem.sym
order = self.ode_problem.order
if order != 1:
return False
match, funcs = match_riccati(eq, f, x)
if not match:
return False
_b0, _b1, _b2 = funcs
b0, b1, b2 = self.wilds()
self._wilds_match = match = {b0: _b0, b1: _b1, b2: _b2}
return True
def _get_general_solution(self, *, simplify_flag: bool = True):
# Match the equation
b0, b1, b2 = self.wilds_match()
fx = self.ode_problem.func
x = self.ode_problem.sym
return solve_riccati(fx, x, b0, b1, b2, gensol=True)
class SecondNonlinearAutonomousConserved(SinglePatternODESolver):
r"""
Gives solution for the autonomous second order nonlinear
differential equation of the form
.. math :: f''(x) = g(f(x))
The solution for this differential equation can be computed
by multiplying by `f'(x)` and integrating on both sides,
converting it into a first order differential equation.
Examples
========
>>> from sympy import Function, symbols, dsolve
>>> f, g = symbols('f g', cls=Function)
>>> x = symbols('x')
>>> eq = f(x).diff(x, 2) - g(f(x))
>>> dsolve(eq, simplify=False)
[Eq(Integral(1/sqrt(C1 + 2*Integral(g(_u), _u)), (_u, f(x))), C2 + x),
Eq(Integral(1/sqrt(C1 + 2*Integral(g(_u), _u)), (_u, f(x))), C2 - x)]
>>> from sympy import exp, log
>>> eq = f(x).diff(x, 2) - exp(f(x)) + log(f(x))
>>> dsolve(eq, simplify=False)
[Eq(Integral(1/sqrt(-2*_u*log(_u) + 2*_u + C1 + 2*exp(_u)), (_u, f(x))), C2 + x),
Eq(Integral(1/sqrt(-2*_u*log(_u) + 2*_u + C1 + 2*exp(_u)), (_u, f(x))), C2 - x)]
References
==========
- http://eqworld.ipmnet.ru/en/solutions/ode/ode0301.pdf
"""
hint = "2nd_nonlinear_autonomous_conserved"
has_integral = True
order = [2]
def _wilds(self, f, x, order):
fy = Wild('fy', exclude=[0, f(x).diff(x), f(x).diff(x, 2)])
return (fy, )
def _equation(self, fx, x, order):
fy = self.wilds()[0]
return fx.diff(x, 2) + fy
def _verify(self, fx):
return self.ode_problem.is_autonomous
def _get_general_solution(self, *, simplify_flag: bool = True):
g = self.wilds_match()[0]
fx = self.ode_problem.func
x = self.ode_problem.sym
u = Dummy('u')
g = g.subs(fx, u)
C1, C2 = self.ode_problem.get_numbered_constants(num=2)
inside = -2*Integral(g, u) + C1
lhs = Integral(1/sqrt(inside), (u, fx))
return [Eq(lhs, C2 + x), Eq(lhs, C2 - x)]
class Liouville(SinglePatternODESolver):
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
"""
hint = "Liouville"
has_integral = True
order = [2]
def _wilds(self, f, x, order):
d = Wild('d', exclude=[f(x).diff(x), f(x).diff(x, 2)])
e = Wild('e', exclude=[f(x).diff(x)])
k = Wild('k', exclude=[f(x).diff(x)])
return d, e, k
def _equation(self, fx, x, order):
# 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
d, e, k = self.wilds()
return d*fx.diff(x, 2) + e*fx.diff(x)**2 + k*fx.diff(x)
def _verify(self, fx):
d, e, k = self.wilds_match()
self.y = Dummy('y')
x = self.ode_problem.sym
self.g = simplify(e/d).subs(fx, self.y)
self.h = simplify(k/d).subs(fx, self.y)
if self.y in self.h.free_symbols or x in self.g.free_symbols:
return False
return True
def _get_general_solution(self, *, simplify_flag: bool = True):
d, e, k = self.wilds_match()
fx = self.ode_problem.func
x = self.ode_problem.sym
C1, C2 = self.ode_problem.get_numbered_constants(num=2)
int = Integral(exp(Integral(self.g, self.y)), (self.y, None, fx))
gen_sol = Eq(int + C1*Integral(exp(-Integral(self.h, x)), x) + C2, 0)
return [gen_sol]
class Separable(SinglePatternODESolver):
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
"""
hint = "separable"
has_integral = True
order = [1]
def _wilds(self, f, x, order):
d = Wild('d', exclude=[f(x).diff(x), f(x).diff(x, 2)])
e = Wild('e', exclude=[f(x).diff(x)])
return d, e
def _equation(self, fx, x, order):
d, e = self.wilds()
return d + e*fx.diff(x)
def _verify(self, fx):
d, e = self.wilds_match()
self.y = Dummy('y')
x = self.ode_problem.sym
d = separatevars(d.subs(fx, self.y))
e = separatevars(e.subs(fx, self.y))
# m1[coeff]*m1[x]*m1[y] + m2[coeff]*m2[x]*m2[y]*y'
self.m1 = separatevars(d, dict=True, symbols=(x, self.y))
self.m2 = separatevars(e, dict=True, symbols=(x, self.y))
if self.m1 and self.m2:
return True
return False
def _get_match_object(self):
fx = self.ode_problem.func
x = self.ode_problem.sym
return self.m1, self.m2, x, fx
def _get_general_solution(self, *, simplify_flag: bool = True):
m1, m2, x, fx = self._get_match_object()
(C1,) = self.ode_problem.get_numbered_constants(num=1)
int = Integral(m2['coeff']*m2[self.y]/m1[self.y],
(self.y, None, fx))
gen_sol = Eq(int, Integral(-m1['coeff']*m1[x]/
m2[x], x) + C1)
return [gen_sol]
class SeparableReduced(Separable):
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, 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
========
:obj:`sympy.solvers.ode.single.Separable`
Examples
========
>>> from sympy import Function, pprint
>>> from sympy.solvers.ode.ode import dsolve
>>> 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), (1 - sqrt(C1*x**2 + 1))/x), Eq(f(x), (sqrt(C1*x**2 + 1) + 1)/x)]
>>> pprint(dsolve(eq, hint='separable_reduced'))
___________ ___________
/ 2 / 2
1 - \/ C1*x + 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
"""
hint = "separable_reduced"
has_integral = True
order = [1]
def _degree(self, expr, x):
# Made this function to calculate the degree of
# x in an expression. If expr will be of form
# x**p*y, (wheare p can be variables/rationals) then it
# will return p.
for val in expr:
if val.has(x):
if isinstance(val, Pow) and val.as_base_exp()[0] == x:
return (val.as_base_exp()[1])
elif val == x:
return (val.as_base_exp()[1])
else:
return self._degree(val.args, x)
return 0
def _powers(self, expr):
# this function will return all the different relative power of x w.r.t f(x).
# expr = x**p * f(x)**q then it will return {p/q}.
pows = set()
fx = self.ode_problem.func
x = self.ode_problem.sym
self.y = Dummy('y')
if isinstance(expr, Add):
exprs = expr.atoms(Add)
elif isinstance(expr, Mul):
exprs = expr.atoms(Mul)
elif isinstance(expr, Pow):
exprs = expr.atoms(Pow)
else:
exprs = {expr}
for arg in exprs:
if arg.has(x):
_, u = arg.as_independent(x, fx)
pow = self._degree((u.subs(fx, self.y), ), x)/self._degree((u.subs(fx, self.y), ), self.y)
pows.add(pow)
return pows
def _verify(self, fx):
num, den = self.wilds_match()
x = self.ode_problem.sym
factor = simplify(x/fx*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)
num, dem = factor.as_numer_denom()
num = expand(num)
dem = expand(dem)
pows = self._powers(num)
pows.update(self._powers(dem))
pows = list(pows)
if(len(pows)==1) and pows[0]!=zoo:
self.t = Dummy('t')
self.r2 = {'t': self.t}
num = num.subs(x**pows[0]*fx, self.t)
dem = dem.subs(x**pows[0]*fx, self.t)
test = num/dem
free = test.free_symbols
if len(free) == 1 and free.pop() == self.t:
self.r2.update({'power' : pows[0], 'u' : test})
return True
return False
return False
def _get_match_object(self):
fx = self.ode_problem.func
x = self.ode_problem.sym
u = self.r2['u'].subs(self.r2['t'], self.y)
ycoeff = 1/(self.y*(self.r2['power'] - u))
m1 = {self.y: 1, x: -1/x, 'coeff': 1}
m2 = {self.y: ycoeff, x: 1, 'coeff': 1}
return m1, m2, x, x**self.r2['power']*fx
class HomogeneousCoeffSubsDepDivIndep(SinglePatternODESolver):
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
:obj:`~sympy.solvers.ode.single.HomogeneousCoeffBest` and
:obj:`~sympy.solvers.ode.single.HomogeneousCoeffSubsIndepDivDep`.
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
"""
hint = "1st_homogeneous_coeff_subs_dep_div_indep"
has_integral = True
order = [1]
def _wilds(self, f, x, order):
d = Wild('d', exclude=[f(x).diff(x), f(x).diff(x, 2)])
e = Wild('e', exclude=[f(x).diff(x)])
return d, e
def _equation(self, fx, x, order):
d, e = self.wilds()
return d + e*fx.diff(x)
def _verify(self, fx):
self.d, self.e = self.wilds_match()
self.y = Dummy('y')
x = self.ode_problem.sym
self.d = separatevars(self.d.subs(fx, self.y))
self.e = separatevars(self.e.subs(fx, self.y))
ordera = homogeneous_order(self.d, x, self.y)
orderb = homogeneous_order(self.e, x, self.y)
if ordera == orderb and ordera is not None:
self.u = Dummy('u')
if simplify((self.d + self.u*self.e).subs({x: 1, self.y: self.u})) != 0:
return True
return False
return False
def _get_match_object(self):
fx = self.ode_problem.func
x = self.ode_problem.sym
self.u1 = Dummy('u1')
xarg = 0
yarg = 0
return [self.d, self.e, fx, x, self.u, self.u1, self.y, xarg, yarg]
def _get_general_solution(self, *, simplify_flag: bool = True):
d, e, fx, x, u, u1, y, xarg, yarg = self._get_match_object()
(C1,) = self.ode_problem.get_numbered_constants(num=1)
int = Integral(
(-e/(d + u1*e)).subs({x: 1, y: u1}),
(u1, None, fx/x))
sol = logcombine(Eq(log(x), int + log(C1)), force=True)
gen_sol = sol.subs(fx, u).subs(((u, u - yarg), (x, x - xarg), (u, fx)))
return [gen_sol]
class HomogeneousCoeffSubsIndepDivDep(SinglePatternODESolver):
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(u1)
| ---------------- d(u1)
| u1*g(u1) + h(u1)
|
/
<BLANKLINE>
f(x) = C1*e
Where `u_1 g(u_1) + h(u_1) \ne 0` and `f(x) \ne 0`.
See also the docstrings of
:obj:`~sympy.solvers.ode.single.HomogeneousCoeffBest` and
:obj:`~sympy.solvers.ode.single.HomogeneousCoeffSubsDepDivIndep`.
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
"""
hint = "1st_homogeneous_coeff_subs_indep_div_dep"
has_integral = True
order = [1]
def _wilds(self, f, x, order):
d = Wild('d', exclude=[f(x).diff(x), f(x).diff(x, 2)])
e = Wild('e', exclude=[f(x).diff(x)])
return d, e
def _equation(self, fx, x, order):
d, e = self.wilds()
return d + e*fx.diff(x)
def _verify(self, fx):
self.d, self.e = self.wilds_match()
self.y = Dummy('y')
x = self.ode_problem.sym
self.d = separatevars(self.d.subs(fx, self.y))
self.e = separatevars(self.e.subs(fx, self.y))
ordera = homogeneous_order(self.d, x, self.y)
orderb = homogeneous_order(self.e, x, self.y)
if ordera == orderb and ordera is not None:
self.u = Dummy('u')
if simplify((self.e + self.u*self.d).subs({x: self.u, self.y: 1})) != 0:
return True
return False
return False
def _get_match_object(self):
fx = self.ode_problem.func
x = self.ode_problem.sym
self.u1 = Dummy('u1')
xarg = 0
yarg = 0
return [self.d, self.e, fx, x, self.u, self.u1, self.y, xarg, yarg]
def _get_general_solution(self, *, simplify_flag: bool = True):
d, e, fx, x, u, u1, y, xarg, yarg = self._get_match_object()
(C1,) = self.ode_problem.get_numbered_constants(num=1)
int = Integral(simplify((-d/(e + u1*d)).subs({x: u1, y: 1})), (u1, None, x/fx))
sol = logcombine(Eq(log(fx), int + log(C1)), force=True)
gen_sol = sol.subs(fx, u).subs(((u, u - yarg), (x, x - xarg), (u, fx)))
return [gen_sol]
class HomogeneousCoeffBest(HomogeneousCoeffSubsIndepDivDep, HomogeneousCoeffSubsDepDivIndep):
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.ode_sol_simplicity`.
See the
:obj:`~sympy.solvers.ode.single.HomogeneousCoeffSubsIndepDivDep`
and
:obj:`~sympy.solvers.ode.single.HomogeneousCoeffSubsDepDivIndep`
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
"""
hint = "1st_homogeneous_coeff_best"
has_integral = False
order = [1]
def _verify(self, fx):
if HomogeneousCoeffSubsIndepDivDep._verify(self, fx) and HomogeneousCoeffSubsDepDivIndep._verify(self, fx):
return True
return False
def _get_general_solution(self, *, simplify_flag: bool = True):
# 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 = HomogeneousCoeffSubsIndepDivDep._get_general_solution(self)
sol2 = HomogeneousCoeffSubsDepDivIndep._get_general_solution(self)
fx = self.ode_problem.func
if simplify_flag:
sol1 = odesimp(self.ode_problem.eq, *sol1, fx, "1st_homogeneous_coeff_subs_indep_div_dep")
sol2 = odesimp(self.ode_problem.eq, *sol2, fx, "1st_homogeneous_coeff_subs_dep_div_indep")
return min([sol1, sol2], key=lambda x: ode_sol_simplicity(x, fx, trysolving=not simplify))
class LinearCoefficients(HomogeneousCoeffBest):
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
========
:obj:`sympy.solvers.ode.single.HomogeneousCoeffBest`
:obj:`sympy.solvers.ode.single.HomogeneousCoeffSubsIndepDivDep`
:obj:`sympy.solvers.ode.single.HomogeneousCoeffSubsDepDivIndep`
Examples
========
>>> from sympy import Function, pprint
>>> from sympy.solvers.ode.ode import dsolve
>>> 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
"""
hint = "linear_coefficients"
has_integral = True
order = [1]
def _wilds(self, f, x, order):
d = Wild('d', exclude=[f(x).diff(x), f(x).diff(x, 2)])
e = Wild('e', exclude=[f(x).diff(x)])
return d, e
def _equation(self, fx, x, order):
d, e = self.wilds()
return d + e*fx.diff(x)
def _verify(self, fx):
self.d, self.e = self.wilds_match()
a, b = self.wilds()
F = self.d/self.e
x = self.ode_problem.sym
params = self._linear_coeff_match(F, fx)
if params:
self.xarg, self.yarg = params
u = Dummy('u')
t = Dummy('t')
self.y = Dummy('y')
# Dummy substitution for df and f(x).
dummy_eq = self.ode_problem.eq.subs(((fx.diff(x), t), (fx, u)))
reps = ((x, x + self.xarg), (u, u + self.yarg), (t, fx.diff(x)), (u, fx))
dummy_eq = simplify(dummy_eq.subs(reps))
# get the re-cast values for e and d
r2 = collect(expand(dummy_eq), [fx.diff(x), fx]).match(a*fx.diff(x) + b)
if r2:
self.d, self.e = r2[b], r2[a]
orderd = homogeneous_order(self.d, x, fx)
ordere = homogeneous_order(self.e, x, fx)
if orderd == ordere and orderd is not None:
self.d = self.d.subs(fx, self.y)
self.e = self.e.subs(fx, self.y)
return True
return False
return False
def _linear_coeff_match(self, 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.single import LinearCoefficients
>>> from sympy.functions.elementary.trigonometric import sin
>>> f = Function('f')
>>> eq = (-25*f(x) - 8*x + 62)/(4*f(x) + 11*x - 11)
>>> obj = LinearCoefficients(eq)
>>> obj._linear_coeff_match(eq, f(x))
(1/9, 22/9)
>>> eq = sin((-5*f(x) - 8*x + 6)/(4*f(x) + x - 1))
>>> obj = LinearCoefficients(eq)
>>> obj._linear_coeff_match(eq, f(x))
(19/27, 2/27)
>>> eq = sin(f(x)/x)
>>> obj = LinearCoefficients(eq)
>>> obj._linear_coeff_match(eq, 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 _get_match_object(self):
fx = self.ode_problem.func
x = self.ode_problem.sym
self.u1 = Dummy('u1')
u = Dummy('u')
return [self.d, self.e, fx, x, u, self.u1, self.y, self.xarg, self.yarg]
class NthOrderReducible(SingleODESolver):
r"""
Solves ODEs that only involve derivatives of the dependent variable using
a substitution of the form `f^n(x) = g(x)`.
For example any second order ODE of the form `f''(x) = h(f'(x), x)` can be
transformed into a pair of 1st order ODEs `g'(x) = h(g(x), x)` and
`f'(x) = g(x)`. Usually the 1st order ODE for `g` is easier to solve. If
that gives an explicit solution for `g` then `f` is found simply by
integration.
Examples
========
>>> from sympy import Function, dsolve, Eq
>>> from sympy.abc import x
>>> f = Function('f')
>>> eq = Eq(x*f(x).diff(x)**2 + f(x).diff(x, 2), 0)
>>> dsolve(eq, f(x), hint='nth_order_reducible')
... # doctest: +NORMALIZE_WHITESPACE
Eq(f(x), C1 - sqrt(-1/C2)*log(-C2*sqrt(-1/C2) + x) + sqrt(-1/C2)*log(C2*sqrt(-1/C2) + x))
"""
hint = "nth_order_reducible"
has_integral = False
def _matches(self):
# Any ODE that can be solved with a substitution and
# repeated integration e.g.:
# `d^2/dx^2(y) + x*d/dx(y) = constant
#f'(x) must be finite for this to work
eq = self.ode_problem.eq_preprocessed
func = self.ode_problem.func
x = self.ode_problem.sym
r"""
Matches any differential equation that can be rewritten with a smaller
order. Only derivatives of ``func`` alone, wrt a single variable,
are considered, and only in them should ``func`` appear.
"""
# ODE only handles functions of 1 variable so this affirms that state
assert len(func.args) == 1
vc = [d.variable_count[0] for d in eq.atoms(Derivative)
if d.expr == func and len(d.variable_count) == 1]
ords = [c for v, c in vc if v == x]
if len(ords) < 2:
return False
self.smallest = min(ords)
# make sure func does not appear outside of derivatives
D = Dummy()
if eq.subs(func.diff(x, self.smallest), D).has(func):
return False
return True
def _get_general_solution(self, *, simplify_flag: bool = True):
eq = self.ode_problem.eq
f = self.ode_problem.func.func
x = self.ode_problem.sym
n = self.smallest
# get a unique function name for g
names = [a.name for a in eq.atoms(AppliedUndef)]
while True:
name = Dummy().name
if name not in names:
g = Function(name)
break
w = f(x).diff(x, n)
geq = eq.subs(w, g(x))
gsol = dsolve(geq, g(x))
if not isinstance(gsol, list):
gsol = [gsol]
# Might be multiple solutions to the reduced ODE:
fsol = []
for gsoli in gsol:
fsoli = dsolve(gsoli.subs(g(x), w), f(x)) # or do integration n times
fsol.append(fsoli)
return fsol
class SecondHypergeometric(SingleODESolver):
r"""
Solves 2nd order linear differential equations.
It computes special function solutions which can be expressed using the
2F1, 1F1 or 0F1 hypergeometric functions.
.. math:: y'' + A(x) y' + B(x) y = 0\text{,}
where `A` and `B` are rational functions.
These kinds of differential equations have solution of non-Liouvillian form.
Given linear ODE can be obtained from 2F1 given by
.. math:: (x^2 - x) y'' + ((a + b + 1) x - c) y' + b a y = 0\text{,}
where {a, b, c} are arbitrary constants.
Notes
=====
The algorithm should find any solution of the form
.. math:: y = P(x) _pF_q(..; ..;\frac{\alpha x^k + \beta}{\gamma x^k + \delta})\text{,}
where pFq is any of 2F1, 1F1 or 0F1 and `P` is an "arbitrary function".
Currently only the 2F1 case is implemented in SymPy but the other cases are
described in the paper and could be implemented in future (contributions
welcome!).
Examples
========
>>> from sympy import Function, dsolve, pprint
>>> from sympy.abc import x
>>> f = Function('f')
>>> eq = (x*x - x)*f(x).diff(x,2) + (5*x - 1)*f(x).diff(x) + 4*f(x)
>>> pprint(dsolve(eq, f(x), '2nd_hypergeometric'))
_
/ / 4 \\ |_ /-1, -1 | \
|C1 + C2*|log(x) + -----||* | | | x|
\ \ x + 1// 2 1 \ 1 | /
f(x) = --------------------------------------------
3
(x - 1)
References
==========
- "Non-Liouvillian solutions for second order linear ODEs" by L. Chan, E.S. Cheb-Terrab
"""
hint = "2nd_hypergeometric"
has_integral = True
def _matches(self):
eq = self.ode_problem.eq_preprocessed
func = self.ode_problem.func
r = match_2nd_hypergeometric(eq, func)
self.match_object = None
if r:
A, B = r
d = equivalence_hypergeometric(A, B, func)
if d:
if d['type'] == "2F1":
self.match_object = match_2nd_2F1_hypergeometric(d['I0'], d['k'], d['sing_point'], func)
if self.match_object is not None:
self.match_object.update({'A':A, 'B':B})
# We can extend it for 1F1 and 0F1 type also.
return self.match_object is not None
def _get_general_solution(self, *, simplify_flag: bool = True):
eq = self.ode_problem.eq
func = self.ode_problem.func
if self.match_object['type'] == "2F1":
sol = get_sol_2F1_hypergeometric(eq, func, self.match_object)
if sol is None:
raise NotImplementedError("The given ODE " + str(eq) + " cannot be solved by"
+ " the hypergeometric method")
return [sol]
class NthLinearConstantCoeffHomogeneous(SingleODESolver):
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.ComplexRootOf` instance will be return
instead.
>>> from sympy import Function, dsolve
>>> 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.
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
"""
hint = "nth_linear_constant_coeff_homogeneous"
has_integral = False
def _matches(self):
eq = self.ode_problem.eq_high_order_free
func = self.ode_problem.func
order = self.ode_problem.order
x = self.ode_problem.sym
self.r = self.ode_problem.get_linear_coefficients(eq, func, order)
if order and self.r and not any(self.r[i].has(x) for i in self.r if i >= 0):
if not self.r[-1]:
return True
else:
return False
return False
def _get_general_solution(self, *, simplify_flag: bool = True):
fx = self.ode_problem.func
order = self.ode_problem.order
roots, collectterms = _get_const_characteristic_eq_sols(self.r, fx, order)
# A generator of constants
constants = self.ode_problem.get_numbered_constants(num=len(roots))
gsol = Add(*[i*j for (i, j) in zip(constants, roots)])
gsol = Eq(fx, gsol)
if simplify_flag:
gsol = _get_simplified_sol([gsol], fx, collectterms)
return [gsol]
class NthLinearConstantCoeffVariationOfParameters(SingleODESolver):
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'))
/ / / x*log(x) 11*x\\\ x
f(x) = |C1 + x*|C2 + x*|C3 + -------- - ----|||*e
\ \ \ 6 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
"""
hint = "nth_linear_constant_coeff_variation_of_parameters"
has_integral = True
def _matches(self):
eq = self.ode_problem.eq_high_order_free
func = self.ode_problem.func
order = self.ode_problem.order
x = self.ode_problem.sym
self.r = self.ode_problem.get_linear_coefficients(eq, func, order)
if order and self.r and not any(self.r[i].has(x) for i in self.r if i >= 0):
if self.r[-1]:
return True
else:
return False
return False
def _get_general_solution(self, *, simplify_flag: bool = True):
eq = self.ode_problem.eq_high_order_free
f = self.ode_problem.func.func
x = self.ode_problem.sym
order = self.ode_problem.order
roots, collectterms = _get_const_characteristic_eq_sols(self.r, f(x), order)
# A generator of constants
constants = self.ode_problem.get_numbered_constants(num=len(roots))
homogen_sol = Add(*[i*j for (i, j) in zip(constants, roots)])
homogen_sol = Eq(f(x), homogen_sol)
homogen_sol = _solve_variation_of_parameters(eq, f(x), roots, homogen_sol, order, self.r, simplify_flag)
if simplify_flag:
homogen_sol = _get_simplified_sol([homogen_sol], f(x), collectterms)
return [homogen_sol]
class NthLinearConstantCoeffUndeterminedCoefficients(SingleODESolver):
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'))
/ / 3\\
| | x || -x 4*sin(2*x) 3*cos(2*x)
f(x) = |C1 + x*|C2 + --||*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
"""
hint = "nth_linear_constant_coeff_undetermined_coefficients"
has_integral = False
def _matches(self):
eq = self.ode_problem.eq_high_order_free
func = self.ode_problem.func
order = self.ode_problem.order
x = self.ode_problem.sym
self.r = self.ode_problem.get_linear_coefficients(eq, func, order)
does_match = False
if order and self.r and not any(self.r[i].has(x) for i in self.r if i >= 0):
if self.r[-1]:
eq_homogeneous = Add(eq, -self.r[-1])
undetcoeff = _undetermined_coefficients_match(self.r[-1], x, func, eq_homogeneous)
if undetcoeff['test']:
self.trialset = undetcoeff['trialset']
does_match = True
return does_match
def _get_general_solution(self, *, simplify_flag: bool = True):
eq = self.ode_problem.eq
f = self.ode_problem.func.func
x = self.ode_problem.sym
order = self.ode_problem.order
roots, collectterms = _get_const_characteristic_eq_sols(self.r, f(x), order)
# A generator of constants
constants = self.ode_problem.get_numbered_constants(num=len(roots))
homogen_sol = Add(*[i*j for (i, j) in zip(constants, roots)])
homogen_sol = Eq(f(x), homogen_sol)
self.r.update({'list': roots, 'sol': homogen_sol, 'simpliy_flag': simplify_flag})
gsol = _solve_undetermined_coefficients(eq, f(x), order, self.r, self.trialset)
if simplify_flag:
gsol = _get_simplified_sol([gsol], f(x), collectterms)
return [gsol]
class NthLinearEulerEqHomogeneous(SingleODESolver):
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:obj:`~.ComplexRootOf` instance will be returned
instead.
>>> from sympy import Function, dsolve
>>> 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
"""
hint = "nth_linear_euler_eq_homogeneous"
has_integral = False
def _matches(self):
eq = self.ode_problem.eq_preprocessed
f = self.ode_problem.func.func
order = self.ode_problem.order
x = self.ode_problem.sym
match = self.ode_problem.get_linear_coefficients(eq, f(x), order)
self.r = None
does_match = False
if order and match:
coeff = match[order]
factor = x**order / coeff
self.r = {i: factor*match[i] for i in match}
if self.r and not any(not _test_term(self.r[i], f(x), i) for i in
self.r if i >= 0):
if not self.r[-1]:
does_match = True
return does_match
def _get_general_solution(self, *, simplify_flag: bool = True):
fx = self.ode_problem.func
eq = self.ode_problem.eq
homogen_sol = _get_euler_characteristic_eq_sols(eq, fx, self.r)[0]
return [homogen_sol]
class NthLinearEulerEqNonhomogeneousVariationOfParameters(SingleODESolver):
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)
"""
hint = "nth_linear_euler_eq_nonhomogeneous_variation_of_parameters"
has_integral = True
def _matches(self):
eq = self.ode_problem.eq_preprocessed
f = self.ode_problem.func.func
order = self.ode_problem.order
x = self.ode_problem.sym
match = self.ode_problem.get_linear_coefficients(eq, f(x), order)
self.r = None
does_match = False
if order and match:
coeff = match[order]
factor = x**order / coeff
self.r = {i: factor*match[i] for i in match}
if self.r and not any(not _test_term(self.r[i], f(x), i) for i in
self.r if i >= 0):
if self.r[-1]:
does_match = True
return does_match
def _get_general_solution(self, *, simplify_flag: bool = True):
eq = self.ode_problem.eq
f = self.ode_problem.func.func
x = self.ode_problem.sym
order = self.ode_problem.order
homogen_sol, roots = _get_euler_characteristic_eq_sols(eq, f(x), self.r)
self.r[-1] = self.r[-1]/self.r[order]
sol = _solve_variation_of_parameters(eq, f(x), roots, homogen_sol, order, self.r, simplify_flag)
return [Eq(f(x), homogen_sol.rhs + (sol.rhs - homogen_sol.rhs)*self.r[order])]
class NthLinearEulerEqNonhomogeneousUndeterminedCoefficients(SingleODESolver):
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)
"""
hint = "nth_linear_euler_eq_nonhomogeneous_undetermined_coefficients"
has_integral = False
def _matches(self):
eq = self.ode_problem.eq_high_order_free
f = self.ode_problem.func.func
order = self.ode_problem.order
x = self.ode_problem.sym
match = self.ode_problem.get_linear_coefficients(eq, f(x), order)
self.r = None
does_match = False
if order and match:
coeff = match[order]
factor = x**order / coeff
self.r = {i: factor*match[i] for i in match}
if self.r and not any(not _test_term(self.r[i], f(x), i) for i in
self.r if i >= 0):
if self.r[-1]:
e, re = posify(self.r[-1].subs(x, exp(x)))
undetcoeff = _undetermined_coefficients_match(e.subs(re), x)
if undetcoeff['test']:
does_match = True
return does_match
def _get_general_solution(self, *, simplify_flag: bool = True):
f = self.ode_problem.func.func
x = self.ode_problem.sym
chareq, eq, symbol = S.Zero, S.Zero, Dummy('x')
for i in self.r.keys():
if i >= 0:
chareq += (self.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(self.r[-1].subs(x, exp(x)))
eq += e.subs(re)
self.const_undet_instance = NthLinearConstantCoeffUndeterminedCoefficients(SingleODEProblem(eq, f(x), x))
sol = self.const_undet_instance.get_general_solution(simplify = simplify_flag)[0]
sol = sol.subs(x, log(x))
sol = sol.subs(f(log(x)), f(x)).expand()
return [sol]
class SecondLinearBessel(SingleODESolver):
r"""
Gives solution of the Bessel differential equation
.. math :: x^2 \frac{d^2y}{dx^2} + x \frac{dy}{dx} y(x) + (x^2-n^2) y(x)
if `n` is integer then the solution is of the form ``Eq(f(x), C0 besselj(n,x)
+ C1 bessely(n,x))`` as both the solutions are linearly independent else if
`n` is a fraction then the solution is of the form ``Eq(f(x), C0 besselj(n,x)
+ C1 besselj(-n,x))`` which can also transform into ``Eq(f(x), C0 besselj(n,x)
+ C1 bessely(n,x))``.
Examples
========
>>> from sympy.abc import x
>>> from sympy import Symbol
>>> v = Symbol('v', positive=True)
>>> from sympy.solvers.ode import dsolve
>>> from sympy import Function
>>> f = Function('f')
>>> y = f(x)
>>> genform = x**2*y.diff(x, 2) + x*y.diff(x) + (x**2 - v**2)*y
>>> dsolve(genform)
Eq(f(x), C1*besselj(v, x) + C2*bessely(v, x))
References
==========
https://www.math24.net/bessel-differential-equation/
"""
hint = "2nd_linear_bessel"
has_integral = False
def _matches(self):
eq = self.ode_problem.eq_high_order_free
f = self.ode_problem.func
order = self.ode_problem.order
x = self.ode_problem.sym
df = f.diff(x)
a = Wild('a', exclude=[f,df])
b = Wild('b', exclude=[x, f,df])
a4 = Wild('a4', exclude=[x,f,df])
b4 = Wild('b4', exclude=[x,f,df])
c4 = Wild('c4', exclude=[x,f,df])
d4 = Wild('d4', exclude=[x,f,df])
a3 = Wild('a3', exclude=[f, df, f.diff(x, 2)])
b3 = Wild('b3', exclude=[f, df, f.diff(x, 2)])
c3 = Wild('c3', exclude=[f, df, f.diff(x, 2)])
deq = a3*(f.diff(x, 2)) + b3*df + c3*f
r = collect(eq,
[f.diff(x, 2), df, f]).match(deq)
if order == 2 and r:
if not all([r[key].is_polynomial() for key in r]):
n, d = eq.as_numer_denom()
eq = expand(n)
r = collect(eq,
[f.diff(x, 2), df, f]).match(deq)
if r and r[a3] != 0:
# leading coeff of f(x).diff(x, 2)
coeff = factor(r[a3]).match(a4*(x-b)**b4)
if coeff:
# if coeff[b4] = 0 means constant coefficient
if coeff[b4] == 0:
return False
point = coeff[b]
else:
return False
if point:
r[a3] = simplify(r[a3].subs(x, x+point))
r[b3] = simplify(r[b3].subs(x, x+point))
r[c3] = simplify(r[c3].subs(x, x+point))
# making a3 in the form of x**2
r[a3] = cancel(r[a3]/(coeff[a4]*(x)**(-2+coeff[b4])))
r[b3] = cancel(r[b3]/(coeff[a4]*(x)**(-2+coeff[b4])))
r[c3] = cancel(r[c3]/(coeff[a4]*(x)**(-2+coeff[b4])))
# checking if b3 is of form c*(x-b)
coeff1 = factor(r[b3]).match(a4*(x))
if coeff1 is None:
return False
# c3 maybe of very complex form so I am simply checking (a - b) form
# if yes later I will match with the standerd form of bessel in a and b
# a, b are wild variable defined above.
_coeff2 = r[c3].match(a - b)
if _coeff2 is None:
return False
# matching with standerd form for c3
coeff2 = factor(_coeff2[a]).match(c4**2*(x)**(2*a4))
if coeff2 is None:
return False
if _coeff2[b] == 0:
coeff2[d4] = 0
else:
coeff2[d4] = factor(_coeff2[b]).match(d4**2)[d4]
self.rn = {'n':coeff2[d4], 'a4':coeff2[c4], 'd4':coeff2[a4]}
self.rn['c4'] = coeff1[a4]
self.rn['b4'] = point
return True
return False
def _get_general_solution(self, *, simplify_flag: bool = True):
f = self.ode_problem.func.func
x = self.ode_problem.sym
n = self.rn['n']
a4 = self.rn['a4']
c4 = self.rn['c4']
d4 = self.rn['d4']
b4 = self.rn['b4']
n = sqrt(n**2 + Rational(1, 4)*(c4 - 1)**2)
(C1, C2) = self.ode_problem.get_numbered_constants(num=2)
return [Eq(f(x), ((x**(Rational(1-c4,2)))*(C1*besselj(n/d4,a4*x**d4/d4)
+ C2*bessely(n/d4,a4*x**d4/d4))).subs(x, x-b4))]
class SecondLinearAiry(SingleODESolver):
r"""
Gives solution of the Airy differential equation
.. math :: \frac{d^2y}{dx^2} + (a + b x) y(x) = 0
in terms of Airy special functions airyai and airybi.
Examples
========
>>> from sympy import dsolve, Function
>>> from sympy.abc import x
>>> f = Function("f")
>>> eq = f(x).diff(x, 2) - x*f(x)
>>> dsolve(eq)
Eq(f(x), C1*airyai(x) + C2*airybi(x))
"""
hint = "2nd_linear_airy"
has_integral = False
def _matches(self):
eq = self.ode_problem.eq_high_order_free
f = self.ode_problem.func
order = self.ode_problem.order
x = self.ode_problem.sym
df = f.diff(x)
a4 = Wild('a4', exclude=[x,f,df])
b4 = Wild('b4', exclude=[x,f,df])
match = self.ode_problem.get_linear_coefficients(eq, f, order)
does_match = False
if order == 2 and match and match[2] != 0:
if match[1].is_zero:
self.rn = cancel(match[0]/match[2]).match(a4+b4*x)
if self.rn and self.rn[b4] != 0:
self.rn = {'b':self.rn[a4],'m':self.rn[b4]}
does_match = True
return does_match
def _get_general_solution(self, *, simplify_flag: bool = True):
f = self.ode_problem.func.func
x = self.ode_problem.sym
(C1, C2) = self.ode_problem.get_numbered_constants(num=2)
b = self.rn['b']
m = self.rn['m']
if m.is_positive:
arg = - b/cbrt(m)**2 - cbrt(m)*x
elif m.is_negative:
arg = - b/cbrt(-m)**2 + cbrt(-m)*x
else:
arg = - b/cbrt(-m)**2 + cbrt(-m)*x
return [Eq(f(x), C1*airyai(arg) + C2*airybi(arg))]
class LieGroup(SingleODESolver):
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 system into another coordinate system where it becomes
invariant under the one-parameter Lie group of translations. The converted
ODE can be easily solved by quadrature. 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, 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
"""
hint = "lie_group"
has_integral = False
def _has_additional_params(self):
return 'xi' in self.ode_problem.params and 'eta' in self.ode_problem.params
def _matches(self):
eq = self.ode_problem.eq
f = self.ode_problem.func.func
order = self.ode_problem.order
x = self.ode_problem.sym
df = f(x).diff(x)
y = Dummy('y')
d = Wild('d', exclude=[df, f(x).diff(x, 2)])
e = Wild('e', exclude=[df])
does_match = False
if self._has_additional_params() and order == 1:
xi = self.ode_problem.params['xi']
eta = self.ode_problem.params['eta']
self.r3 = {'xi': xi, 'eta': eta}
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)
self.r3.update(r)
does_match = True
return does_match
def _get_general_solution(self, *, simplify_flag: bool = True):
eq = self.ode_problem.eq
x = self.ode_problem.sym
func = self.ode_problem.func
order = self.ode_problem.order
df = func.diff(x)
try:
eqsol = solve(eq, df)
except NotImplementedError:
eqsol = []
desols = []
for s in eqsol:
sol = _ode_lie_group(s, func, order, match=self.r3)
if sol:
desols.extend(sol)
if desols == []:
raise NotImplementedError("The given ODE " + str(eq) + " cannot be solved by"
+ " the lie group method")
return desols
solver_map = {
'factorable': Factorable,
'nth_linear_constant_coeff_homogeneous': NthLinearConstantCoeffHomogeneous,
'nth_linear_euler_eq_homogeneous': NthLinearEulerEqHomogeneous,
'nth_linear_constant_coeff_undetermined_coefficients': NthLinearConstantCoeffUndeterminedCoefficients,
'nth_linear_euler_eq_nonhomogeneous_undetermined_coefficients': NthLinearEulerEqNonhomogeneousUndeterminedCoefficients,
'separable': Separable,
'1st_exact': FirstExact,
'1st_linear': FirstLinear,
'Bernoulli': Bernoulli,
'Riccati_special_minus2': RiccatiSpecial,
'1st_rational_riccati': RationalRiccati,
'1st_homogeneous_coeff_best': HomogeneousCoeffBest,
'1st_homogeneous_coeff_subs_indep_div_dep': HomogeneousCoeffSubsIndepDivDep,
'1st_homogeneous_coeff_subs_dep_div_indep': HomogeneousCoeffSubsDepDivIndep,
'almost_linear': AlmostLinear,
'linear_coefficients': LinearCoefficients,
'separable_reduced': SeparableReduced,
'nth_linear_constant_coeff_variation_of_parameters': NthLinearConstantCoeffVariationOfParameters,
'nth_linear_euler_eq_nonhomogeneous_variation_of_parameters': NthLinearEulerEqNonhomogeneousVariationOfParameters,
'Liouville': Liouville,
'2nd_linear_airy': SecondLinearAiry,
'2nd_linear_bessel': SecondLinearBessel,
'2nd_hypergeometric': SecondHypergeometric,
'nth_order_reducible': NthOrderReducible,
'2nd_nonlinear_autonomous_conserved': SecondNonlinearAutonomousConserved,
'nth_algebraic': NthAlgebraic,
'lie_group': LieGroup,
}
# Avoid circular import:
from .ode import dsolve, ode_sol_simplicity, odesimp, homogeneous_order
|
8f9c617e9f319d733fb1455221466398c26f2dc583a5f9a697a6abedd007930d | r"""
This module contains :py:meth:`~sympy.solvers.ode.riccati.solve_riccati`,
a function which gives all rational particular solutions to first order
Riccati ODEs. A general first order Riccati ODE is given by -
.. math:: y' = b_0(x) + b_1(x)w + b_2(x)w^2
where `b_0, b_1` and `b_2` can be arbitrary rational functions of `x`
with `b_2 \ne 0`. When `b_2 = 0`, the equation is not a Riccati ODE
anymore and becomes a Linear ODE. Similarly, when `b_0 = 0`, the equation
is a Bernoulli ODE. The algorithm presented below can find rational
solution(s) to all ODEs with `b_2 \ne 0` that have a rational solution,
or prove that no rational solution exists for the equation.
Background
==========
A Riccati equation can be transformed to its normal form
.. math:: y' + y^2 = a(x)
using the transformation
.. math:: y = -b_2(x) - \frac{b'_2(x)}{2 b_2(x)} - \frac{b_1(x)}{2}
where `a(x)` is given by
.. math:: a(x) = \frac{1}{4}\left(\frac{b_2'}{b_2} + b_1\right)^2 - \frac{1}{2}\left(\frac{b_2'}{b_2} + b_1\right)' - b_0 b_2
Thus, we can develop an algorithm to solve for the Riccati equation
in its normal form, which would in turn give us the solution for
the original Riccati equation.
Algorithm
=========
The algorithm implemented here is presented in the Ph.D thesis
"Rational and Algebraic Solutions of First-Order Algebraic ODEs"
by N. Thieu Vo. The entire thesis can be found here -
https://www3.risc.jku.at/publications/download/risc_5387/PhDThesisThieu.pdf
We have only implemented the Rational Riccati solver (Algorithm 11,
Pg 78-82 in Thesis). Before we proceed towards the implementation
of the algorithm, a few definitions to understand are -
1. Valuation of a Rational Function at `\infty`:
The valuation of a rational function `p(x)` at `\infty` is equal
to the difference between the degree of the denominator and the
numerator of `p(x)`.
NOTE: A general definition of valuation of a rational function
at any value of `x` can be found in Pg 63 of the thesis, but
is not of any interest for this algorithm.
2. Zeros and Poles of a Rational Function:
Let `a(x) = \frac{S(x)}{T(x)}, T \ne 0` be a rational function
of `x`. Then -
a. The Zeros of `a(x)` are the roots of `S(x)`.
b. The Poles of `a(x)` are the roots of `T(x)`. However, `\infty`
can also be a pole of a(x). We say that `a(x)` has a pole at
`\infty` if `a(\frac{1}{x})` has a pole at 0.
Every pole is associated with an order that is equal to the multiplicity
of its appearence as a root of `T(x)`. A pole is called a simple pole if
it has an order 1. Similarly, a pole is called a multiple pole if it has
an order `\ge` 2.
Necessary Conditions
====================
For a Riccati equation in its normal form,
.. math:: y' + y^2 = a(x)
we can define
a. A pole is called a movable pole if it is a pole of `y(x)` and is not
a pole of `a(x)`.
b. Similarly, a pole is called a non-movable pole if it is a pole of both
`y(x)` and `a(x)`.
Then, the algorithm states that a rational solution exists only if -
a. Every pole of `a(x)` must be either a simple pole or a multiple pole
of even order.
b. The valuation of `a(x)` at `\infty` must be even or be `\ge` 2.
This algorithm finds all possible rational solutions for the Riccati ODE.
If no rational solutions are found, it means that no rational solutions
exist.
The algorithm works for Riccati ODEs where the coefficients are rational
functions in the independent variable `x` with rational number coefficients
i.e. in `Q(x)`. The coefficients in the rational function cannot be floats,
irrational numbers, symbols or any other kind of expression. The reasons
for this are -
1. When using symbols, different symbols could take the same value and this
would affect the multiplicity of poles if symbols are present here.
2. An integer degree bound is required to calculate a polynomial solution
to an auxiliary differential equation, which in turn gives the particular
solution for the original ODE. If symbols/floats/irrational numbers are
present, we cannot determine if the expression for the degree bound is an
integer or not.
Solution
========
With these definitions, we can state a general form for the solution of
the equation. `y(x)` must have the form -
.. math:: y(x) = \sum_{i=1}^{n} \sum_{j=1}^{r_i} \frac{c_{ij}}{(x - x_i)^j} + \sum_{i=1}^{m} \frac{1}{x - \chi_i} + \sum_{i=0}^{N} d_i x^i
where `x_1, x_2, ..., x_n` are non-movable poles of `a(x)`,
`\chi_1, \chi_2, ..., \chi_m` are movable poles of `a(x)`, and the values
of `N, n, r_1, r_2, ..., r_n` can be determined from `a(x)`. The
coefficient vectors `(d_0, d_1, ..., d_N)` and `(c_{i1}, c_{i2}, ..., c_{i r_i})`
can be determined from `a(x)`. We will have 2 choices each of these vectors
and part of the procedure is figuring out which of the 2 should be used
to get the solution correctly.
Implementation
==============
In this implementatin, we use ``Poly`` to represent a rational function
rather than using ``Expr`` since ``Poly`` is much faster. Since we cannot
represent rational functions directly using ``Poly``, we instead represent
a rational function with 2 ``Poly`` objects - one for its numerator and
the other for its denominator.
The code is written to match the steps given in the thesis (Pg 82)
Step 0 : Match the equation -
Find `b_0, b_1` and `b_2`. If `b_2 = 0` or no such functions exist, raise
an error
Step 1 : Transform the equation to its normal form as explained in the
theory section.
Step 2 : Initialize an empty set of solutions, ``sol``.
Step 3 : If `a(x) = 0`, append `\frac{1}/{(x - C1)}` to ``sol``.
Step 4 : If `a(x)` is a rational non-zero number, append `\pm \sqrt{a}`
to ``sol``.
Step 5 : Find the poles and their multiplicities of `a(x)`. Let
the number of poles be `n`. Also find the valuation of `a(x)` at
`\infty` using ``val_at_inf``.
NOTE: Although the algorithm considers `\infty` as a pole, it is
not mentioned if it a part of the set of finite poles. `\infty`
is NOT a part of the set of finite poles. If a pole exists at
`\infty`, we use its multiplicty to find the laurent series of
`a(x)` about `\infty`.
Step 6 : Find `n` c-vectors (one for each pole) and 1 d-vector using
``construct_c`` and ``construct_d``. Now, determine all the ``2**(n + 1)``
combinations of choosing between 2 choices for each of the `n` c-vectors
and 1 d-vector.
NOTE: The equation for `d_{-1}` in Case 4 (Pg 80) has a printinig
mistake. The term `- d_N` must be replaced with `-N d_N`. The same
has been explained in the code as well.
For each of these above combinations, do
Step 8 : Compute `m` in ``compute_m_ybar``. `m` is the degree bound of
the polynomial solution we must find for the auxiliary equation.
Step 9 : In ``compute_m_ybar``, compute ybar as well where ``ybar`` is
one part of y(x) -
.. math:: \overline{y}(x) = \sum_{i=1}^{n} \sum_{j=1}^{r_i} \frac{c_{ij}}{(x - x_i)^j} + \sum_{i=0}^{N} d_i x^i
Step 10 : If `m` is a non-negative integer -
Step 11: Find a polynomial solution of degree `m` for the auxiliary equation.
There are 2 cases possible -
a. `m` is a non-negative integer: We can solve for the coefficients
in `p(x)` using Undetermined Coefficients.
b. `m` is not a non-negative integer: In this case, we cannot find
a polynomial solution to the auxiliary equation, and hence, we ignore
this value of `m`.
Step 12 : For each `p(x)` that exists, append `ybar + \frac{p'(x)}{p(x)}`
to ``sol``.
Step 13 : For each solution in ``sol``, apply an inverse transformation,
so that the solutions of the original equation are found using the
solutions of the equation in its normal form.
"""
from itertools import product
from sympy.core import S
from sympy.core.add import Add
from sympy.core.numbers import oo, Float
from sympy.core.function import count_ops
from sympy.core.relational import Eq
from sympy.core.symbol import symbols, Symbol, Dummy
from sympy.functions import sqrt, exp
from sympy.functions.elementary.complexes import sign
from sympy.integrals.integrals import Integral
from sympy.polys.domains import ZZ
from sympy.polys.polytools import Poly
from sympy.polys.polyroots import roots
from sympy.solvers.solveset import linsolve
def riccati_normal(w, x, b1, b2):
"""
Given a solution `w(x)` to the equation
.. math:: w'(x) = b_0(x) + b_1(x)*w(x) + b_2(x)*w(x)^2
and rational function coefficients `b_1(x)` and
`b_2(x)`, this function transforms the solution to
give a solution `y(x)` for its corresponding normal
Riccati ODE
.. math:: y'(x) + y(x)^2 = a(x)
using the transformation
.. math:: y(x) = -b_2(x)*w(x) - b'_2(x)/(2*b_2(x)) - b_1(x)/2
"""
return -b2*w - b2.diff(x)/(2*b2) - b1/2
def riccati_inverse_normal(y, x, b1, b2, bp=None):
"""
Inverse transforming the solution to the normal
Riccati ODE to get the solution to the Riccati ODE.
"""
# bp is the expression which is independent of the solution
# and hence, it need not be computed again
if bp is None:
bp = -b2.diff(x)/(2*b2**2) - b1/(2*b2)
# w(x) = -y(x)/b2(x) - b2'(x)/(2*b2(x)^2) - b1(x)/(2*b2(x))
return -y/b2 + bp
def riccati_reduced(eq, f, x):
"""
Convert a Riccati ODE into its corresponding
normal Riccati ODE.
"""
match, funcs = match_riccati(eq, f, x)
# If equation is not a Riccati ODE, exit
if not match:
return False
# Using the rational functions, find the expression for a(x)
b0, b1, b2 = funcs
a = -b0*b2 + b1**2/4 - b1.diff(x)/2 + 3*b2.diff(x)**2/(4*b2**2) + b1*b2.diff(x)/(2*b2) - \
b2.diff(x, 2)/(2*b2)
# Normal form of Riccati ODE is f'(x) + f(x)^2 = a(x)
return f(x).diff(x) + f(x)**2 - a
def linsolve_dict(eq, syms):
"""
Get the output of linsolve as a dict
"""
# Convert tuple type return value of linsolve
# to a dictionary for ease of use
sol = linsolve(eq, syms)
if not sol:
return {}
return {k:v for k, v in zip(syms, list(sol)[0])}
def match_riccati(eq, f, x):
"""
A function that matches and returns the coefficients
if an equation is a Riccati ODE
Parameters
==========
eq: Equation to be matched
f: Dependent variable
x: Independent variable
Returns
=======
match: True if equation is a Riccati ODE, False otherwise
funcs: [b0, b1, b2] if match is True, [] otherwise. Here,
b0, b1 and b2 are rational functions which match the equation.
"""
# Group terms based on f(x)
if isinstance(eq, Eq):
eq = eq.lhs - eq.rhs
eq = eq.expand().collect(f(x))
cf = eq.coeff(f(x).diff(x))
# There must be an f(x).diff(x) term.
# eq must be an Add object since we are using the expanded
# equation and it must have atleast 2 terms (b2 != 0)
if cf != 0 and isinstance(eq, Add):
# Divide all coefficients by the coefficient of f(x).diff(x)
# and add the terms again to get the same equation
eq = Add(*((x/cf).cancel() for x in eq.args)).collect(f(x))
# Match the equation with the pattern
b1 = -eq.coeff(f(x))
b2 = -eq.coeff(f(x)**2)
b0 = (f(x).diff(x) - b1*f(x) - b2*f(x)**2 - eq).expand()
funcs = [b0, b1, b2]
# Check if coefficients are not symbols and floats
if any([len(x.atoms(Symbol)) > 1 or len(x.atoms(Float)) for x in [b0, b1, b2]]):
return False, []
# If b_0(x) contains f(x), it is not a Riccati ODE
if len(b0.atoms(f)) or not all([b2 != 0, b0.is_rational_function(x), \
b1.is_rational_function(x), b2.is_rational_function(x)]):
return False, []
return True, funcs
return False, []
def val_at_inf(num, den, x):
# Valuation of a rational function at oo = deg(denom) - deg(numer)
return den.degree(x) - num.degree(x)
def check_necessary_conds(val_inf, muls):
"""
The necessary conditions for a rational solution
to exist are as follows -
i) Every pole of a(x) must be either a simple pole
or a multiple pole of even order.
ii) The valuation of a(x) at infinity must be even
or be greater than or equal to 2.
Here, a simple pole is a pole with multiplicity 1
and a multiple pole is a pole with multiplicity
greater than 1.
"""
return (val_inf >= 2 or (val_inf <= 0 and val_inf%2 == 0)) and \
all([mul == 1 or (mul%2 == 0 and mul >= 2) for mul in muls])
def inverse_transform_poly(num, den, x):
"""
A function to make the substitution
x -> 1/x in a rational function that
is represented using Poly objects for
numerator and denominator.
"""
# Declare for reuse
one = Poly(1, x)
xpoly = Poly(x, x)
# Check if degree of numerator is same as denominator
pwr = val_at_inf(num, den, x)
if pwr >= 0:
# Denominator has greater degree. Substituting x with
# 1/x would make the extra power go to the numerator
if num.expr != 0:
num = num.transform(one, xpoly) * x**pwr
den = den.transform(one, xpoly)
else:
# Numerator has greater degree. Substituting x with
# 1/x would make the extra power go to the denominator
num = num.transform(one, xpoly)
den = den.transform(one, xpoly) * x**(-pwr)
return num.cancel(den, include=True)
def limit_at_inf(num, den, x):
"""
Find the limit of a rational function
at oo
"""
# pwr = degree(num) - degree(den)
pwr = -val_at_inf(num, den, x)
# Numerator has a greater degree than denominator
# Limit at infinity would depend on the sign of the
# leading coefficients of numerator and denominator
if pwr > 0:
return oo*sign(num.LC()/den.LC())
# Degree of numerator is equal to that of denominator
# Limit at infinity is just the ratio of leading coeffs
elif pwr == 0:
return num.LC()/den.LC()
# Degree of numerator is less than that of denominator
# Limit at infinity is just 0
else:
return 0
def construct_c_case_1(num, den, x, pole):
# Find the coefficient of 1/(x - pole)**2 in the
# Laurent series expansion of a(x) about pole.
num1, den1 = (num*Poly((x - pole)**2, x, extension=True)).cancel(den, include=True)
r = (num1.subs(x, pole))/(den1.subs(x, pole))
# If multiplicity is 2, the coefficient to be added
# in the c-vector is c = (1 +- sqrt(1 + 4*r))/2
if r != -S(1)/4:
return [[(1 + sqrt(1 + 4*r))/2], [(1 - sqrt(1 + 4*r))/2]]
return [[S(1)/2]]
def construct_c_case_2(num, den, x, pole, mul):
# Generate the coefficients using the recurrence
# relation mentioned in (5.14) in the thesis (Pg 80)
# r_i = mul/2
ri = mul//2
# Find the Laurent series coefficients about the pole
ser = rational_laurent_series(num, den, x, pole, mul, 6)
# Start with an empty memo to store the coefficients
# This is for the plus case
cplus = [0 for i in range(ri)]
# Base Case
cplus[ri-1] = sqrt(ser[2*ri])
# Iterate backwards to find all coefficients
s = ri - 1
sm = 0
for s in range(ri-1, 0, -1):
sm = 0
for j in range(s+1, ri):
sm += cplus[j-1]*cplus[ri+s-j-1]
if s!= 1:
cplus[s-1] = (ser[ri+s] - sm)/(2*cplus[ri-1])
# Memo for the minus case
cminus = [-x for x in cplus]
# Find the 0th coefficient in the recurrence
cplus[0] = (ser[ri+s] - sm - ri*cplus[ri-1])/(2*cplus[ri-1])
cminus[0] = (ser[ri+s] - sm - ri*cminus[ri-1])/(2*cminus[ri-1])
# Add both the plus and minus cases' coefficients
if cplus != cminus:
return [cplus, cminus]
return cplus
def construct_c_case_3():
# If multiplicity is 1, the coefficient to be added
# in the c-vector is 1 (no choice)
return [[1]]
def construct_c(num, den, x, poles, muls):
"""
Helper function to calculate the coefficients
in the c-vector for each pole.
"""
c = []
for pole, mul in zip(poles, muls):
c.append([])
# Case 3
if mul == 1:
# Add the coefficients from Case 3
c[-1].extend(construct_c_case_3())
# Case 1
elif mul == 2:
# Add the coefficients from Case 1
c[-1].extend(construct_c_case_1(num, den, x, pole))
# Case 2
else:
# Add the coefficients from Case 2
c[-1].extend(construct_c_case_2(num, den, x, pole, mul))
return c
def construct_d_case_4(ser, N):
# Initialize an empty vector
dplus = [0 for i in range(N+2)]
# d_N = sqrt(a_{2*N})
dplus[N] = sqrt(ser[2*N])
# Use the recurrence relations to find
# the value of d_s
for s in range(N-1, -2, -1):
sm = 0
for j in range(s+1, N):
sm += dplus[j]*dplus[N+s-j]
if s != -1:
dplus[s] = (ser[N+s] - sm)/(2*dplus[N])
# Coefficients for the case of d_N = -sqrt(a_{2*N})
dminus = [-x for x in dplus]
# The third equation in Eq 5.15 of the thesis is WRONG!
# d_N must be replaced with N*d_N in that equation.
dplus[-1] = (ser[N+s] - N*dplus[N] - sm)/(2*dplus[N])
dminus[-1] = (ser[N+s] - N*dminus[N] - sm)/(2*dminus[N])
if dplus != dminus:
return [dplus, dminus]
return dplus
def construct_d_case_5(ser):
# List to store coefficients for plus case
dplus = [0, 0]
# d_0 = sqrt(a_0)
dplus[0] = sqrt(ser[0])
# d_(-1) = a_(-1)/(2*d_0)
dplus[-1] = ser[-1]/(2*dplus[0])
# Coefficients for the minus case are just the negative
# of the coefficients for the positive case.
dminus = [-x for x in dplus]
if dplus != dminus:
return [dplus, dminus]
return dplus
def construct_d_case_6(num, den, x):
# s_oo = lim x->0 1/x**2 * a(1/x) which is equivalent to
# s_oo = lim x->oo x**2 * a(x)
s_inf = limit_at_inf(Poly(x**2, x)*num, den, x)
# d_(-1) = (1 +- sqrt(1 + 4*s_oo))/2
if s_inf != -S(1)/4:
return [[(1 + sqrt(1 + 4*s_inf))/2], [(1 - sqrt(1 + 4*s_inf))/2]]
return [[S(1)/2]]
def construct_d(num, den, x, val_inf):
"""
Helper function to calculate the coefficients
in the d-vector based on the valuation of the
function at oo.
"""
N = -val_inf//2
# Multiplicity of oo as a pole
mul = -val_inf if val_inf < 0 else 0
ser = rational_laurent_series(num, den, x, oo, mul, 1)
# Case 4
if val_inf < 0:
d = construct_d_case_4(ser, N)
# Case 5
elif val_inf == 0:
d = construct_d_case_5(ser)
# Case 6
else:
d = construct_d_case_6(num, den, x)
return d
def rational_laurent_series(num, den, x, r, m, n):
r"""
The function computes the Laurent series coefficients
of a rational function.
Parameters
==========
num: A Poly object that is the numerator of `f(x)`.
den: A Poly object that is the denominator of `f(x)`.
x: The variable of expansion of the series.
r: The point of expansion of the series.
m: Multiplicity of r if r is a pole of `f(x)`. Should
be zero otherwise.
n: Order of the term upto which the series is expanded.
Returns
=======
series: A dictionary that has power of the term as key
and coefficient of that term as value.
Below is a basic outline of how the Laurent series of a
rational function `f(x)` about `x_0` is being calculated -
1. Substitute `x + x_0` in place of `x`. If `x_0`
is a pole of `f(x)`, multiply the expression by `x^m`
where `m` is the multiplicity of `x_0`. Denote the
the resulting expression as g(x). We do this substitution
so that we can now find the Laurent series of g(x) about
`x = 0`.
2. We can then assume that the Laurent series of `g(x)`
takes the following form -
.. math:: g(x) = \frac{num(x)}{den(x)} = \sum_{m = 0}^{\infty} a_m x^m
where `a_m` denotes the Laurent series coefficients.
3. Multiply the denominator to the RHS of the equation
and form a recurrence relation for the coefficients `a_m`.
"""
one = Poly(1, x, extension=True)
if r == oo:
# Series at x = oo is equal to first transforming
# the function from x -> 1/x and finding the
# series at x = 0
num, den = inverse_transform_poly(num, den, x)
r = S(0)
if r:
# For an expansion about a non-zero point, a
# transformation from x -> x + r must be made
num = num.transform(Poly(x + r, x, extension=True), one)
den = den.transform(Poly(x + r, x, extension=True), one)
# Remove the pole from the denominator if the series
# expansion is about one of the poles
num, den = (num*x**m).cancel(den, include=True)
# Equate coefficients for the first terms (base case)
maxdegree = 1 + max(num.degree(), den.degree())
syms = symbols(f'a:{maxdegree}', cls=Dummy)
diff = num - den * Poly(syms[::-1], x)
coeff_diffs = diff.all_coeffs()[::-1][:maxdegree]
(coeffs, ) = linsolve(coeff_diffs, syms)
# Use the recursion relation for the rest
recursion = den.all_coeffs()[::-1]
div, rec_rhs = recursion[0], recursion[1:]
series = list(coeffs)
while len(series) < n:
next_coeff = Add(*(c*series[-1-n] for n, c in enumerate(rec_rhs))) / div
series.append(-next_coeff)
series = {m - i: val for i, val in enumerate(series)}
return series
def compute_m_ybar(x, poles, choice, N):
"""
Helper function to calculate -
1. m - The degree bound for the polynomial
solution that must be found for the auxiliary
differential equation.
2. ybar - Part of the solution which can be
computed using the poles, c and d vectors.
"""
ybar = 0
m = Poly(choice[-1][-1], x, extension=True)
# Calculate the first (nested) summation for ybar
# as given in Step 9 of the Thesis (Pg 82)
for i in range(len(poles)):
for j in range(len(choice[i])):
ybar += choice[i][j]/(x - poles[i])**(j+1)
m -= Poly(choice[i][0], x, extension=True)
# Calculate the second summation for ybar
for i in range(N+1):
ybar += choice[-1][i]*x**i
return (m.expr, ybar)
def solve_aux_eq(numa, dena, numy, deny, x, m):
"""
Helper function to find a polynomial solution
of degree m for the auxiliary differential
equation.
"""
# Assume that the solution is of the type
# p(x) = C_0 + C_1*x + ... + C_{m-1}*x**(m-1) + x**m
psyms = symbols(f'C0:{m}', cls=Dummy)
K = ZZ[psyms]
psol = Poly(K.gens, x, domain=K) + Poly(x**m, x, domain=K)
# Eq (5.16) in Thesis - Pg 81
auxeq = (dena*(numy.diff(x)*deny - numy*deny.diff(x) + numy**2) - numa*deny**2)*psol
if m >= 1:
px = psol.diff(x)
auxeq += px*(2*numy*deny*dena)
if m >= 2:
auxeq += px.diff(x)*(deny**2*dena)
if m != 0:
# m is a non-zero integer. Find the constant terms using undetermined coefficients
return psol, linsolve_dict(auxeq.all_coeffs(), psyms), True
else:
# m == 0 . Check if 1 (x**0) is a solution to the auxiliary equation
return S(1), auxeq, auxeq == 0
def remove_redundant_sols(sol1, sol2, x):
"""
Helper function to remove redundant
solutions to the differential equation.
"""
# If y1 and y2 are redundant solutions, there is
# some value of the arbitrary constant for which
# they will be equal
syms1 = sol1.atoms(Symbol, Dummy)
syms2 = sol2.atoms(Symbol, Dummy)
num1, den1 = [Poly(e, x, extension=True) for e in sol1.together().as_numer_denom()]
num2, den2 = [Poly(e, x, extension=True) for e in sol2.together().as_numer_denom()]
# Cross multiply
e = num1*den2 - den1*num2
# Check if there are any constants
syms = list(e.atoms(Symbol, Dummy))
if len(syms):
# Find values of constants for which solutions are equal
redn = linsolve(e.all_coeffs(), syms)
if len(redn):
# Return the general solution over a particular solution
if len(syms1) > len(syms2):
return sol2
# If both have constants, return the lesser complex solution
elif len(syms1) == len(syms2):
return sol1 if count_ops(syms1) >= count_ops(syms2) else sol2
else:
return sol1
def get_gen_sol_from_part_sol(part_sols, a, x):
""""
Helper function which computes the general
solution for a Riccati ODE from its particular
solutions.
There are 3 cases to find the general solution
from the particular solutions for a Riccati ODE
depending on the number of particular solution(s)
we have - 1, 2 or 3.
For more information, see Section 6 of
"Methods of Solution of the Riccati Differential Equation"
by D. R. Haaheim and F. M. Stein
"""
# If no particular solutions are found, a general
# solution cannot be found
if len(part_sols) == 0:
return []
# In case of a single particular solution, the general
# solution can be found by using the substitution
# y = y1 + 1/z and solving a Bernoulli ODE to find z.
elif len(part_sols) == 1:
y1 = part_sols[0]
i = exp(Integral(2*y1, x))
z = i * Integral(a/i, x)
z = z.doit()
if a == 0 or z == 0:
return y1
return y1 + 1/z
# In case of 2 particular solutions, the general solution
# can be found by solving a separable equation. This is
# the most common case, i.e. most Riccati ODEs have 2
# rational particular solutions.
elif len(part_sols) == 2:
y1, y2 = part_sols
# One of them already has a constant
if len(y1.atoms(Dummy)) + len(y2.atoms(Dummy)) > 0:
u = exp(Integral(y2 - y1, x)).doit()
# Introduce a constant
else:
C1 = Dummy('C1')
u = C1*exp(Integral(y2 - y1, x)).doit()
if u == 1:
return y2
return (y2*u - y1)/(u - 1)
# In case of 3 particular solutions, a closed form
# of the general solution can be obtained directly
else:
y1, y2, y3 = part_sols[:3]
C1 = Dummy('C1')
return (C1 + 1)*y2*(y1 - y3)/(C1*y1 + y2 - (C1 + 1)*y3)
def solve_riccati(fx, x, b0, b1, b2, gensol=False):
"""
The main function that gives particular/general
solutions to Riccati ODEs that have atleast 1
rational particular solution.
"""
# Step 1 : Convert to Normal Form
a = -b0*b2 + b1**2/4 - b1.diff(x)/2 + 3*b2.diff(x)**2/(4*b2**2) + b1*b2.diff(x)/(2*b2) - \
b2.diff(x, 2)/(2*b2)
a_t = a.together()
num, den = [Poly(e, x, extension=True) for e in a_t.as_numer_denom()]
num, den = num.cancel(den, include=True)
# Step 2
presol = []
# Step 3 : a(x) is 0
if num == 0:
presol.append(1/(x + Dummy('C1')))
# Step 4 : a(x) is a non-zero constant
elif x not in num.free_symbols.union(den.free_symbols):
presol.extend([sqrt(a), -sqrt(a)])
# Step 5 : Find poles and valuation at infinity
poles = roots(den, x)
poles, muls = list(poles.keys()), list(poles.values())
val_inf = val_at_inf(num, den, x)
if len(poles):
# Check necessary conditions (outlined in the module docstring)
if not check_necessary_conds(val_inf, muls):
raise ValueError("Rational Solution doesn't exist")
# Step 6
# Construct c-vectors for each singular point
c = construct_c(num, den, x, poles, muls)
# Construct d vectors for each singular point
d = construct_d(num, den, x, val_inf)
# Step 7 : Iterate over all possible combinations and return solutions
# For each possible combination, generate an array of 0's and 1's
# where 0 means pick 1st choice and 1 means pick the second choice.
# NOTE: We could exit from the loop if we find 3 particular solutions,
# but it is not implemented here as -
# a. Finding 3 particular solutions is very rare. Most of the time,
# only 2 particular solutions are found.
# b. In case we exit after finding 3 particular solutions, it might
# happen that 1 or 2 of them are redundant solutions. So, instead of
# spending some more time in computing the particular solutions,
# we will end up computing the general solution from a single
# particular solution which is usually slower than computing the
# general solution from 2 or 3 particular solutions.
c.append(d)
choices = product(*c)
for choice in choices:
m, ybar = compute_m_ybar(x, poles, choice, -val_inf//2)
numy, deny = [Poly(e, x, extension=True) for e in ybar.together().as_numer_denom()]
# Step 10 : Check if a valid solution exists. If yes, also check
# if m is a non-negative integer
if m.is_nonnegative == True and m.is_integer == True:
# Step 11 : Find polynomial solutions of degree m for the auxiliary equation
psol, coeffs, exists = solve_aux_eq(num, den, numy, deny, x, m)
# Step 12 : If valid polynomial solution exists, append solution.
if exists:
# m == 0 case
if psol == 1 and coeffs == 0:
# p(x) = 1, so p'(x)/p(x) term need not be added
presol.append(ybar)
# m is a positive integer and there are valid coefficients
elif len(coeffs):
# Substitute the valid coefficients to get p(x)
psol = psol.xreplace(coeffs)
# y(x) = ybar(x) + p'(x)/p(x)
presol.append(ybar + psol.diff(x)/psol)
# Remove redundant solutions from the list of existing solutions
remove = set()
for i in range(len(presol)):
for j in range(i+1, len(presol)):
rem = remove_redundant_sols(presol[i], presol[j], x)
if rem is not None:
remove.add(rem)
sols = [x for x in presol if x not in remove]
# Step 15 : Inverse transform the solutions of the equation in normal form
bp = -b2.diff(x)/(2*b2**2) - b1/(2*b2)
# If general solution is required, compute it from the particular solutions
if gensol:
sols = [get_gen_sol_from_part_sol(sols, a, x)]
# Inverse transform the particular solutions
presol = [Eq(fx, riccati_inverse_normal(y, x, b1, b2, bp).cancel(extension=True)) for y in sols]
return presol
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