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""" Functions to support rewriting of SymPy expressions """
from __future__ import print_function, division
from sympy import Expr
from sympy.assumptions import ask
from sympy.strategies.tools import subs
from sympy.unify.usympy import rebuild, unify
def rewriterule(source, target, variables=(), condition=None, assume=None):
""" Rewrite rule
Transform expressions that match source into expressions that match target
treating all `variables` as wilds.
Examples
========
>>> from sympy.abc import w, x, y, z
>>> from sympy.unify.rewrite import rewriterule
>>> from sympy.utilities import default_sort_key
>>> rl = rewriterule(x + y, x**y, [x, y])
>>> sorted(rl(z + 3), key=default_sort_key)
[3**z, z**3]
Use ``condition`` to specify additional requirements. Inputs are taken in
the same order as is found in variables.
>>> rl = rewriterule(x + y, x**y, [x, y], lambda x, y: x.is_integer)
>>> list(rl(z + 3))
[3**z]
Use ``assume`` to specify additional requirements using new assumptions.
>>> from sympy.assumptions import Q
>>> rl = rewriterule(x + y, x**y, [x, y], assume=Q.integer(x))
>>> list(rl(z + 3))
[3**z]
Assumptions for the local context are provided at rule runtime
>>> list(rl(w + z, Q.integer(z)))
[z**w]
"""
def rewrite_rl(expr, assumptions=True):
for match in unify(source, expr, {}, variables=variables):
if (condition and
not condition(*[match.get(var, var) for var in variables])):
continue
if (assume and not ask(assume.xreplace(match), assumptions)):
continue
expr2 = subs(match)(target)
if isinstance(expr2, Expr):
expr2 = rebuild(expr2)
yield expr2
return rewrite_rl
|
ead25053ad668c74b22921f86a324250c8ff7691e31ad0a51998706d18aa0132
|
r"""
Wigner, Clebsch-Gordan, Racah, and Gaunt coefficients
Collection of functions for calculating Wigner 3j, 6j, 9j,
Clebsch-Gordan, Racah as well as Gaunt coefficients exactly, all
evaluating to a rational number times the square root of a rational
number [Rasch03]_.
Please see the description of the individual functions for further
details and examples.
References
~~~~~~~~~~
.. [Rasch03] J. Rasch and A. C. H. Yu, 'Efficient Storage Scheme for
Pre-calculated Wigner 3j, 6j and Gaunt Coefficients', SIAM
J. Sci. Comput. Volume 25, Issue 4, pp. 1416-1428 (2003)
Credits and Copyright
~~~~~~~~~~~~~~~~~~~~~
This code was taken from Sage with the permission of all authors:
https://groups.google.com/forum/#!topic/sage-devel/M4NZdu-7O38
AUTHORS:
- Jens Rasch (2009-03-24): initial version for Sage
- Jens Rasch (2009-05-31): updated to sage-4.0
Copyright (C) 2008 Jens Rasch <[email protected]>
"""
from __future__ import print_function, division
from sympy import (Integer, pi, sqrt, sympify, Dummy, S, Sum, Ynm,
Function)
from sympy.core.compatibility import range
# This list of precomputed factorials is needed to massively
# accelerate future calculations of the various coefficients
_Factlist = [1]
def _calc_factlist(nn):
r"""
Function calculates a list of precomputed factorials in order to
massively accelerate future calculations of the various
coefficients.
INPUT:
- ``nn`` - integer, highest factorial to be computed
OUTPUT:
list of integers -- the list of precomputed factorials
EXAMPLES:
Calculate list of factorials::
sage: from sage.functions.wigner import _calc_factlist
sage: _calc_factlist(10)
[1, 1, 2, 6, 24, 120, 720, 5040, 40320, 362880, 3628800]
"""
if nn >= len(_Factlist):
for ii in range(len(_Factlist), int(nn + 1)):
_Factlist.append(_Factlist[ii - 1] * ii)
return _Factlist[:int(nn) + 1]
def wigner_3j(j_1, j_2, j_3, m_1, m_2, m_3):
r"""
Calculate the Wigner 3j symbol `\operatorname{Wigner3j}(j_1,j_2,j_3,m_1,m_2,m_3)`.
INPUT:
- ``j_1``, ``j_2``, ``j_3``, ``m_1``, ``m_2``, ``m_3`` - integer or half integer
OUTPUT:
Rational number times the square root of a rational number.
Examples
========
>>> from sympy.physics.wigner import wigner_3j
>>> wigner_3j(2, 6, 4, 0, 0, 0)
sqrt(715)/143
>>> wigner_3j(2, 6, 4, 0, 0, 1)
0
It is an error to have arguments that are not integer or half
integer values::
sage: wigner_3j(2.1, 6, 4, 0, 0, 0)
Traceback (most recent call last):
...
ValueError: j values must be integer or half integer
sage: wigner_3j(2, 6, 4, 1, 0, -1.1)
Traceback (most recent call last):
...
ValueError: m values must be integer or half integer
NOTES:
The Wigner 3j symbol obeys the following symmetry rules:
- invariant under any permutation of the columns (with the
exception of a sign change where `J:=j_1+j_2+j_3`):
.. math::
\begin{aligned}
\operatorname{Wigner3j}(j_1,j_2,j_3,m_1,m_2,m_3)
&=\operatorname{Wigner3j}(j_3,j_1,j_2,m_3,m_1,m_2) \\
&=\operatorname{Wigner3j}(j_2,j_3,j_1,m_2,m_3,m_1) \\
&=(-1)^J \operatorname{Wigner3j}(j_3,j_2,j_1,m_3,m_2,m_1) \\
&=(-1)^J \operatorname{Wigner3j}(j_1,j_3,j_2,m_1,m_3,m_2) \\
&=(-1)^J \operatorname{Wigner3j}(j_2,j_1,j_3,m_2,m_1,m_3)
\end{aligned}
- invariant under space inflection, i.e.
.. math::
\operatorname{Wigner3j}(j_1,j_2,j_3,m_1,m_2,m_3)
=(-1)^J \operatorname{Wigner3j}(j_1,j_2,j_3,-m_1,-m_2,-m_3)
- symmetric with respect to the 72 additional symmetries based on
the work by [Regge58]_
- zero for `j_1`, `j_2`, `j_3` not fulfilling triangle relation
- zero for `m_1 + m_2 + m_3 \neq 0`
- zero for violating any one of the conditions
`j_1 \ge |m_1|`, `j_2 \ge |m_2|`, `j_3 \ge |m_3|`
ALGORITHM:
This function uses the algorithm of [Edmonds74]_ to calculate the
value of the 3j symbol exactly. Note that the formula contains
alternating sums over large factorials and is therefore unsuitable
for finite precision arithmetic and only useful for a computer
algebra system [Rasch03]_.
REFERENCES:
.. [Regge58] 'Symmetry Properties of Clebsch-Gordan Coefficients',
T. Regge, Nuovo Cimento, Volume 10, pp. 544 (1958)
.. [Edmonds74] 'Angular Momentum in Quantum Mechanics',
A. R. Edmonds, Princeton University Press (1974)
AUTHORS:
- Jens Rasch (2009-03-24): initial version
"""
if int(j_1 * 2) != j_1 * 2 or int(j_2 * 2) != j_2 * 2 or \
int(j_3 * 2) != j_3 * 2:
raise ValueError("j values must be integer or half integer")
if int(m_1 * 2) != m_1 * 2 or int(m_2 * 2) != m_2 * 2 or \
int(m_3 * 2) != m_3 * 2:
raise ValueError("m values must be integer or half integer")
if m_1 + m_2 + m_3 != 0:
return 0
prefid = Integer((-1) ** int(j_1 - j_2 - m_3))
m_3 = -m_3
a1 = j_1 + j_2 - j_3
if a1 < 0:
return 0
a2 = j_1 - j_2 + j_3
if a2 < 0:
return 0
a3 = -j_1 + j_2 + j_3
if a3 < 0:
return 0
if (abs(m_1) > j_1) or (abs(m_2) > j_2) or (abs(m_3) > j_3):
return 0
maxfact = max(j_1 + j_2 + j_3 + 1, j_1 + abs(m_1), j_2 + abs(m_2),
j_3 + abs(m_3))
_calc_factlist(int(maxfact))
argsqrt = Integer(_Factlist[int(j_1 + j_2 - j_3)] *
_Factlist[int(j_1 - j_2 + j_3)] *
_Factlist[int(-j_1 + j_2 + j_3)] *
_Factlist[int(j_1 - m_1)] *
_Factlist[int(j_1 + m_1)] *
_Factlist[int(j_2 - m_2)] *
_Factlist[int(j_2 + m_2)] *
_Factlist[int(j_3 - m_3)] *
_Factlist[int(j_3 + m_3)]) / \
_Factlist[int(j_1 + j_2 + j_3 + 1)]
ressqrt = sqrt(argsqrt)
if ressqrt.is_complex:
ressqrt = ressqrt.as_real_imag()[0]
imin = max(-j_3 + j_1 + m_2, -j_3 + j_2 - m_1, 0)
imax = min(j_2 + m_2, j_1 - m_1, j_1 + j_2 - j_3)
sumres = 0
for ii in range(int(imin), int(imax) + 1):
den = _Factlist[ii] * \
_Factlist[int(ii + j_3 - j_1 - m_2)] * \
_Factlist[int(j_2 + m_2 - ii)] * \
_Factlist[int(j_1 - ii - m_1)] * \
_Factlist[int(ii + j_3 - j_2 + m_1)] * \
_Factlist[int(j_1 + j_2 - j_3 - ii)]
sumres = sumres + Integer((-1) ** ii) / den
res = ressqrt * sumres * prefid
return res
def clebsch_gordan(j_1, j_2, j_3, m_1, m_2, m_3):
r"""
Calculates the Clebsch-Gordan coefficient
`\left\langle j_1 m_1 \; j_2 m_2 | j_3 m_3 \right\rangle`.
The reference for this function is [Edmonds74]_.
INPUT:
- ``j_1``, ``j_2``, ``j_3``, ``m_1``, ``m_2``, ``m_3`` - integer or half integer
OUTPUT:
Rational number times the square root of a rational number.
EXAMPLES::
>>> from sympy import S
>>> from sympy.physics.wigner import clebsch_gordan
>>> clebsch_gordan(S(3)/2, S(1)/2, 2, S(3)/2, S(1)/2, 2)
1
>>> clebsch_gordan(S(3)/2, S(1)/2, 1, S(3)/2, -S(1)/2, 1)
sqrt(3)/2
>>> clebsch_gordan(S(3)/2, S(1)/2, 1, -S(1)/2, S(1)/2, 0)
-sqrt(2)/2
NOTES:
The Clebsch-Gordan coefficient will be evaluated via its relation
to Wigner 3j symbols:
.. math::
\left\langle j_1 m_1 \; j_2 m_2 | j_3 m_3 \right\rangle
=(-1)^{j_1-j_2+m_3} \sqrt{2j_3+1}
\operatorname{Wigner3j}(j_1,j_2,j_3,m_1,m_2,-m_3)
See also the documentation on Wigner 3j symbols which exhibit much
higher symmetry relations than the Clebsch-Gordan coefficient.
AUTHORS:
- Jens Rasch (2009-03-24): initial version
"""
res = (-1) ** sympify(j_1 - j_2 + m_3) * sqrt(2 * j_3 + 1) * \
wigner_3j(j_1, j_2, j_3, m_1, m_2, -m_3)
return res
def _big_delta_coeff(aa, bb, cc, prec=None):
r"""
Calculates the Delta coefficient of the 3 angular momenta for
Racah symbols. Also checks that the differences are of integer
value.
INPUT:
- ``aa`` - first angular momentum, integer or half integer
- ``bb`` - second angular momentum, integer or half integer
- ``cc`` - third angular momentum, integer or half integer
- ``prec`` - precision of the ``sqrt()`` calculation
OUTPUT:
double - Value of the Delta coefficient
EXAMPLES::
sage: from sage.functions.wigner import _big_delta_coeff
sage: _big_delta_coeff(1,1,1)
1/2*sqrt(1/6)
"""
if int(aa + bb - cc) != (aa + bb - cc):
raise ValueError("j values must be integer or half integer and fulfill the triangle relation")
if int(aa + cc - bb) != (aa + cc - bb):
raise ValueError("j values must be integer or half integer and fulfill the triangle relation")
if int(bb + cc - aa) != (bb + cc - aa):
raise ValueError("j values must be integer or half integer and fulfill the triangle relation")
if (aa + bb - cc) < 0:
return 0
if (aa + cc - bb) < 0:
return 0
if (bb + cc - aa) < 0:
return 0
maxfact = max(aa + bb - cc, aa + cc - bb, bb + cc - aa, aa + bb + cc + 1)
_calc_factlist(maxfact)
argsqrt = Integer(_Factlist[int(aa + bb - cc)] *
_Factlist[int(aa + cc - bb)] *
_Factlist[int(bb + cc - aa)]) / \
Integer(_Factlist[int(aa + bb + cc + 1)])
ressqrt = sqrt(argsqrt)
if prec:
ressqrt = ressqrt.evalf(prec).as_real_imag()[0]
return ressqrt
def racah(aa, bb, cc, dd, ee, ff, prec=None):
r"""
Calculate the Racah symbol `W(a,b,c,d;e,f)`.
INPUT:
- ``a``, ..., ``f`` - integer or half integer
- ``prec`` - precision, default: ``None``. Providing a precision can
drastically speed up the calculation.
OUTPUT:
Rational number times the square root of a rational number
(if ``prec=None``), or real number if a precision is given.
Examples
========
>>> from sympy.physics.wigner import racah
>>> racah(3,3,3,3,3,3)
-1/14
NOTES:
The Racah symbol is related to the Wigner 6j symbol:
.. math::
\operatorname{Wigner6j}(j_1,j_2,j_3,j_4,j_5,j_6)
=(-1)^{j_1+j_2+j_4+j_5} W(j_1,j_2,j_5,j_4,j_3,j_6)
Please see the 6j symbol for its much richer symmetries and for
additional properties.
ALGORITHM:
This function uses the algorithm of [Edmonds74]_ to calculate the
value of the 6j symbol exactly. Note that the formula contains
alternating sums over large factorials and is therefore unsuitable
for finite precision arithmetic and only useful for a computer
algebra system [Rasch03]_.
AUTHORS:
- Jens Rasch (2009-03-24): initial version
"""
prefac = _big_delta_coeff(aa, bb, ee, prec) * \
_big_delta_coeff(cc, dd, ee, prec) * \
_big_delta_coeff(aa, cc, ff, prec) * \
_big_delta_coeff(bb, dd, ff, prec)
if prefac == 0:
return 0
imin = max(aa + bb + ee, cc + dd + ee, aa + cc + ff, bb + dd + ff)
imax = min(aa + bb + cc + dd, aa + dd + ee + ff, bb + cc + ee + ff)
maxfact = max(imax + 1, aa + bb + cc + dd, aa + dd + ee + ff,
bb + cc + ee + ff)
_calc_factlist(maxfact)
sumres = 0
for kk in range(int(imin), int(imax) + 1):
den = _Factlist[int(kk - aa - bb - ee)] * \
_Factlist[int(kk - cc - dd - ee)] * \
_Factlist[int(kk - aa - cc - ff)] * \
_Factlist[int(kk - bb - dd - ff)] * \
_Factlist[int(aa + bb + cc + dd - kk)] * \
_Factlist[int(aa + dd + ee + ff - kk)] * \
_Factlist[int(bb + cc + ee + ff - kk)]
sumres = sumres + Integer((-1) ** kk * _Factlist[kk + 1]) / den
res = prefac * sumres * (-1) ** int(aa + bb + cc + dd)
return res
def wigner_6j(j_1, j_2, j_3, j_4, j_5, j_6, prec=None):
r"""
Calculate the Wigner 6j symbol `\operatorname{Wigner6j}(j_1,j_2,j_3,j_4,j_5,j_6)`.
INPUT:
- ``j_1``, ..., ``j_6`` - integer or half integer
- ``prec`` - precision, default: ``None``. Providing a precision can
drastically speed up the calculation.
OUTPUT:
Rational number times the square root of a rational number
(if ``prec=None``), or real number if a precision is given.
Examples
========
>>> from sympy.physics.wigner import wigner_6j
>>> wigner_6j(3,3,3,3,3,3)
-1/14
>>> wigner_6j(5,5,5,5,5,5)
1/52
It is an error to have arguments that are not integer or half
integer values or do not fulfill the triangle relation::
sage: wigner_6j(2.5,2.5,2.5,2.5,2.5,2.5)
Traceback (most recent call last):
...
ValueError: j values must be integer or half integer and fulfill the triangle relation
sage: wigner_6j(0.5,0.5,1.1,0.5,0.5,1.1)
Traceback (most recent call last):
...
ValueError: j values must be integer or half integer and fulfill the triangle relation
NOTES:
The Wigner 6j symbol is related to the Racah symbol but exhibits
more symmetries as detailed below.
.. math::
\operatorname{Wigner6j}(j_1,j_2,j_3,j_4,j_5,j_6)
=(-1)^{j_1+j_2+j_4+j_5} W(j_1,j_2,j_5,j_4,j_3,j_6)
The Wigner 6j symbol obeys the following symmetry rules:
- Wigner 6j symbols are left invariant under any permutation of
the columns:
.. math::
\begin{aligned}
\operatorname{Wigner6j}(j_1,j_2,j_3,j_4,j_5,j_6)
&=\operatorname{Wigner6j}(j_3,j_1,j_2,j_6,j_4,j_5) \\
&=\operatorname{Wigner6j}(j_2,j_3,j_1,j_5,j_6,j_4) \\
&=\operatorname{Wigner6j}(j_3,j_2,j_1,j_6,j_5,j_4) \\
&=\operatorname{Wigner6j}(j_1,j_3,j_2,j_4,j_6,j_5) \\
&=\operatorname{Wigner6j}(j_2,j_1,j_3,j_5,j_4,j_6)
\end{aligned}
- They are invariant under the exchange of the upper and lower
arguments in each of any two columns, i.e.
.. math::
\operatorname{Wigner6j}(j_1,j_2,j_3,j_4,j_5,j_6)
=\operatorname{Wigner6j}(j_1,j_5,j_6,j_4,j_2,j_3)
=\operatorname{Wigner6j}(j_4,j_2,j_6,j_1,j_5,j_3)
=\operatorname{Wigner6j}(j_4,j_5,j_3,j_1,j_2,j_6)
- additional 6 symmetries [Regge59]_ giving rise to 144 symmetries
in total
- only non-zero if any triple of `j`'s fulfill a triangle relation
ALGORITHM:
This function uses the algorithm of [Edmonds74]_ to calculate the
value of the 6j symbol exactly. Note that the formula contains
alternating sums over large factorials and is therefore unsuitable
for finite precision arithmetic and only useful for a computer
algebra system [Rasch03]_.
REFERENCES:
.. [Regge59] 'Symmetry Properties of Racah Coefficients',
T. Regge, Nuovo Cimento, Volume 11, pp. 116 (1959)
"""
res = (-1) ** int(j_1 + j_2 + j_4 + j_5) * \
racah(j_1, j_2, j_5, j_4, j_3, j_6, prec)
return res
def wigner_9j(j_1, j_2, j_3, j_4, j_5, j_6, j_7, j_8, j_9, prec=None):
r"""
Calculate the Wigner 9j symbol
`\operatorname{Wigner9j}(j_1,j_2,j_3,j_4,j_5,j_6,j_7,j_8,j_9)`.
INPUT:
- ``j_1``, ..., ``j_9`` - integer or half integer
- ``prec`` - precision, default: ``None``. Providing a precision can
drastically speed up the calculation.
OUTPUT:
Rational number times the square root of a rational number
(if ``prec=None``), or real number if a precision is given.
Examples
========
>>> from sympy.physics.wigner import wigner_9j
>>> wigner_9j(1,1,1, 1,1,1, 1,1,0 ,prec=64) # ==1/18
0.05555555...
>>> wigner_9j(1/2,1/2,0, 1/2,3/2,1, 0,1,1 ,prec=64) # ==1/6
0.1666666...
It is an error to have arguments that are not integer or half
integer values or do not fulfill the triangle relation::
sage: wigner_9j(0.5,0.5,0.5, 0.5,0.5,0.5, 0.5,0.5,0.5,prec=64)
Traceback (most recent call last):
...
ValueError: j values must be integer or half integer and fulfill the triangle relation
sage: wigner_9j(1,1,1, 0.5,1,1.5, 0.5,1,2.5,prec=64)
Traceback (most recent call last):
...
ValueError: j values must be integer or half integer and fulfill the triangle relation
ALGORITHM:
This function uses the algorithm of [Edmonds74]_ to calculate the
value of the 3j symbol exactly. Note that the formula contains
alternating sums over large factorials and is therefore unsuitable
for finite precision arithmetic and only useful for a computer
algebra system [Rasch03]_.
"""
imax = int(min(j_1 + j_9, j_2 + j_6, j_4 + j_8) * 2)
imin = imax % 2
sumres = 0
for kk in range(imin, int(imax) + 1, 2):
sumres = sumres + (kk + 1) * \
racah(j_1, j_2, j_9, j_6, j_3, kk / 2, prec) * \
racah(j_4, j_6, j_8, j_2, j_5, kk / 2, prec) * \
racah(j_1, j_4, j_9, j_8, j_7, kk / 2, prec)
return sumres
def gaunt(l_1, l_2, l_3, m_1, m_2, m_3, prec=None):
r"""
Calculate the Gaunt coefficient.
The Gaunt coefficient is defined as the integral over three
spherical harmonics:
.. math::
\begin{aligned}
\operatorname{Gaunt}(l_1,l_2,l_3,m_1,m_2,m_3)
&=\int Y_{l_1,m_1}(\Omega)
Y_{l_2,m_2}(\Omega) Y_{l_3,m_3}(\Omega) \,d\Omega \\
&=\sqrt{\frac{(2l_1+1)(2l_2+1)(2l_3+1)}{4\pi}}
\operatorname{Wigner3j}(l_1,l_2,l_3,0,0,0)
\operatorname{Wigner3j}(l_1,l_2,l_3,m_1,m_2,m_3)
\end{aligned}
INPUT:
- ``l_1``, ``l_2``, ``l_3``, ``m_1``, ``m_2``, ``m_3`` - integer
- ``prec`` - precision, default: ``None``. Providing a precision can
drastically speed up the calculation.
OUTPUT:
Rational number times the square root of a rational number
(if ``prec=None``), or real number if a precision is given.
Examples
========
>>> from sympy.physics.wigner import gaunt
>>> gaunt(1,0,1,1,0,-1)
-1/(2*sqrt(pi))
>>> gaunt(1000,1000,1200,9,3,-12).n(64)
0.00689500421922113448...
It is an error to use non-integer values for `l` and `m`::
sage: gaunt(1.2,0,1.2,0,0,0)
Traceback (most recent call last):
...
ValueError: l values must be integer
sage: gaunt(1,0,1,1.1,0,-1.1)
Traceback (most recent call last):
...
ValueError: m values must be integer
NOTES:
The Gaunt coefficient obeys the following symmetry rules:
- invariant under any permutation of the columns
.. math::
\begin{aligned}
Y(l_1,l_2,l_3,m_1,m_2,m_3)
&=Y(l_3,l_1,l_2,m_3,m_1,m_2) \\
&=Y(l_2,l_3,l_1,m_2,m_3,m_1) \\
&=Y(l_3,l_2,l_1,m_3,m_2,m_1) \\
&=Y(l_1,l_3,l_2,m_1,m_3,m_2) \\
&=Y(l_2,l_1,l_3,m_2,m_1,m_3)
\end{aligned}
- invariant under space inflection, i.e.
.. math::
Y(l_1,l_2,l_3,m_1,m_2,m_3)
=Y(l_1,l_2,l_3,-m_1,-m_2,-m_3)
- symmetric with respect to the 72 Regge symmetries as inherited
for the `3j` symbols [Regge58]_
- zero for `l_1`, `l_2`, `l_3` not fulfilling triangle relation
- zero for violating any one of the conditions: `l_1 \ge |m_1|`,
`l_2 \ge |m_2|`, `l_3 \ge |m_3|`
- non-zero only for an even sum of the `l_i`, i.e.
`L = l_1 + l_2 + l_3 = 2n` for `n` in `\mathbb{N}`
ALGORITHM:
This function uses the algorithm of [Liberatodebrito82]_ to
calculate the value of the Gaunt coefficient exactly. Note that
the formula contains alternating sums over large factorials and is
therefore unsuitable for finite precision arithmetic and only
useful for a computer algebra system [Rasch03]_.
REFERENCES:
.. [Liberatodebrito82] 'FORTRAN program for the integral of three
spherical harmonics', A. Liberato de Brito,
Comput. Phys. Commun., Volume 25, pp. 81-85 (1982)
AUTHORS:
- Jens Rasch (2009-03-24): initial version for Sage
"""
if int(l_1) != l_1 or int(l_2) != l_2 or int(l_3) != l_3:
raise ValueError("l values must be integer")
if int(m_1) != m_1 or int(m_2) != m_2 or int(m_3) != m_3:
raise ValueError("m values must be integer")
sumL = l_1 + l_2 + l_3
bigL = sumL // 2
a1 = l_1 + l_2 - l_3
if a1 < 0:
return 0
a2 = l_1 - l_2 + l_3
if a2 < 0:
return 0
a3 = -l_1 + l_2 + l_3
if a3 < 0:
return 0
if sumL % 2:
return 0
if (m_1 + m_2 + m_3) != 0:
return 0
if (abs(m_1) > l_1) or (abs(m_2) > l_2) or (abs(m_3) > l_3):
return 0
imin = max(-l_3 + l_1 + m_2, -l_3 + l_2 - m_1, 0)
imax = min(l_2 + m_2, l_1 - m_1, l_1 + l_2 - l_3)
maxfact = max(l_1 + l_2 + l_3 + 1, imax + 1)
_calc_factlist(maxfact)
argsqrt = (2 * l_1 + 1) * (2 * l_2 + 1) * (2 * l_3 + 1) * \
_Factlist[l_1 - m_1] * _Factlist[l_1 + m_1] * _Factlist[l_2 - m_2] * \
_Factlist[l_2 + m_2] * _Factlist[l_3 - m_3] * _Factlist[l_3 + m_3] / \
(4*pi)
ressqrt = sqrt(argsqrt)
prefac = Integer(_Factlist[bigL] * _Factlist[l_2 - l_1 + l_3] *
_Factlist[l_1 - l_2 + l_3] * _Factlist[l_1 + l_2 - l_3])/ \
_Factlist[2 * bigL + 1]/ \
(_Factlist[bigL - l_1] *
_Factlist[bigL - l_2] * _Factlist[bigL - l_3])
sumres = 0
for ii in range(int(imin), int(imax) + 1):
den = _Factlist[ii] * _Factlist[ii + l_3 - l_1 - m_2] * \
_Factlist[l_2 + m_2 - ii] * _Factlist[l_1 - ii - m_1] * \
_Factlist[ii + l_3 - l_2 + m_1] * _Factlist[l_1 + l_2 - l_3 - ii]
sumres = sumres + Integer((-1) ** ii) / den
res = ressqrt * prefac * sumres * Integer((-1) ** (bigL + l_3 + m_1 - m_2))
if prec is not None:
res = res.n(prec)
return res
class Wigner3j(Function):
def doit(self, **hints):
if all(obj.is_number for obj in self.args):
return wigner_3j(*self.args)
else:
return self
def dot_rot_grad_Ynm(j, p, l, m, theta, phi):
r"""
Returns dot product of rotational gradients of spherical harmonics.
This function returns the right hand side of the following expression:
.. math ::
\vec{R}Y{_j^{p}} \cdot \vec{R}Y{_l^{m}} = (-1)^{m+p}
\sum\limits_{k=|l-j|}^{l+j}Y{_k^{m+p}} * \alpha_{l,m,j,p,k} *
\frac{1}{2} (k^2-j^2-l^2+k-j-l)
Arguments
=========
j, p, l, m .... indices in spherical harmonics (expressions or integers)
theta, phi .... angle arguments in spherical harmonics
Example
=======
>>> from sympy import symbols
>>> from sympy.physics.wigner import dot_rot_grad_Ynm
>>> theta, phi = symbols("theta phi")
>>> dot_rot_grad_Ynm(3, 2, 2, 0, theta, phi).doit()
3*sqrt(55)*Ynm(5, 2, theta, phi)/(11*sqrt(pi))
"""
j = sympify(j)
p = sympify(p)
l = sympify(l)
m = sympify(m)
theta = sympify(theta)
phi = sympify(phi)
k = Dummy("k")
def alpha(l,m,j,p,k):
return sqrt((2*l+1)*(2*j+1)*(2*k+1)/(4*pi)) * \
Wigner3j(j, l, k, S(0), S(0), S(0)) * Wigner3j(j, l, k, p, m, -m-p)
return (-S(1))**(m+p) * Sum(Ynm(k, m+p, theta, phi) * alpha(l,m,j,p,k) / 2 \
*(k**2-j**2-l**2+k-j-l), (k, abs(l-j), l+j))
|
78e28750f51137ee91ab6d5732d5ca225f9516eded438556f340e99ab714d03a
|
from sympy.tensor.tensor import (TensExpr, TensMul)
class PartialDerivative(TensExpr):
"""
Partial derivative for tensor expressions.
Examples
========
>>> from sympy.tensor.tensor import TensorIndexType, tensorhead
>>> from sympy.tensor.toperators import PartialDerivative
>>> from sympy import symbols
>>> L = TensorIndexType("L")
>>> A = tensorhead("A", [L], [[1]])
>>> i, j = symbols("i j")
>>> expr = PartialDerivative(A(i), A(j))
>>> expr
PartialDerivative(A(i), A(j))
The ``PartialDerivative`` object behaves like a tensorial expression:
>>> expr.get_indices()
[i, j]
Indices can be contracted:
>>> PartialDerivative(A(i), A(-i))
PartialDerivative(A(L_0), A(-L_0))
"""
def __new__(cls, expr, *variables):
# Flatten:
if isinstance(expr, PartialDerivative):
variables = expr.variables + variables
expr = expr.expr
# TODO: check that all variables have rank 1.
args, indices, free, dum = TensMul._tensMul_contract_indices([expr] +
list(variables), replace_indices=True)
obj = TensExpr.__new__(cls, *args)
obj._indices = indices
obj._free = free
obj._dum = dum
return obj
def doit(self):
args, indices, free, dum = TensMul._tensMul_contract_indices(self.args)
obj = self.func(*args)
obj._indices = indices
obj._free = free
obj._dum = dum
return obj
def get_indices(self):
return self._indices
@property
def expr(self):
return self.args[0]
@property
def variables(self):
return self.args[1:]
def _extract_data(self, replacement_dict):
from .array import derive_by_array, tensorcontraction
indices, array = self.expr._extract_data(replacement_dict)
for variable in self.variables:
var_indices, var_array = variable._extract_data(replacement_dict)
coeff_array, var_array = zip(*[i.as_coeff_Mul() for i in var_array])
array = derive_by_array(array, var_array)
array = array.as_mutable()
varindex = var_indices[0]
# Remove coefficients of base vector:
coeff_index = [0] + [slice(None) for i in range(len(indices))]
for i, coeff in enumerate(coeff_array):
coeff_index[0] = i
array[tuple(coeff_index)] /= coeff
if -varindex in indices:
pos = indices.index(-varindex)
array = tensorcontraction(array, (0, pos+1))
indices.pop(pos)
else:
indices.append(varindex)
return indices, array
|
1667ef8eb8a4e3b879f5f606a0ddfc91481e538a54c8cacb9361dc94324a97bf
|
"""
This module defines tensors with abstract index notation.
The abstract index notation has been first formalized by Penrose.
Tensor indices are formal objects, with a tensor type; there is no
notion of index range, it is only possible to assign the dimension,
used to trace the Kronecker delta; the dimension can be a Symbol.
The Einstein summation convention is used.
The covariant indices are indicated with a minus sign in front of the index.
For instance the tensor ``t = p(a)*A(b,c)*q(-c)`` has the index ``c``
contracted.
A tensor expression ``t`` can be called; called with its
indices in sorted order it is equal to itself:
in the above example ``t(a, b) == t``;
one can call ``t`` with different indices; ``t(c, d) == p(c)*A(d,a)*q(-a)``.
The contracted indices are dummy indices, internally they have no name,
the indices being represented by a graph-like structure.
Tensors are put in canonical form using ``canon_bp``, which uses
the Butler-Portugal algorithm for canonicalization using the monoterm
symmetries of the tensors.
If there is a (anti)symmetric metric, the indices can be raised and
lowered when the tensor is put in canonical form.
"""
from __future__ import print_function, division
from collections import defaultdict
import operator
import itertools
from sympy import Rational, prod, Integer
from sympy.combinatorics.tensor_can import get_symmetric_group_sgs, \
bsgs_direct_product, canonicalize, riemann_bsgs
from sympy.core import Basic, Expr, sympify, Add, Mul, S
from sympy.core.compatibility import string_types, reduce, range, SYMPY_INTS
from sympy.core.containers import Tuple, Dict
from sympy.core.decorators import deprecated
from sympy.core.symbol import Symbol, symbols
from sympy.core.sympify import CantSympify, _sympify
from sympy.core.operations import AssocOp
from sympy.matrices import eye
from sympy.utilities.exceptions import SymPyDeprecationWarning
import warnings
@deprecated(useinstead=".replace_with_arrays", issue=15276, deprecated_since_version="1.4")
def deprecate_data():
pass
class _IndexStructure(CantSympify):
"""
This class handles the indices (free and dummy ones). It contains the
algorithms to manage the dummy indices replacements and contractions of
free indices under multiplications of tensor expressions, as well as stuff
related to canonicalization sorting, getting the permutation of the
expression and so on. It also includes tools to get the ``TensorIndex``
objects corresponding to the given index structure.
"""
def __init__(self, free, dum, index_types, indices, canon_bp=False):
self.free = free
self.dum = dum
self.index_types = index_types
self.indices = indices
self._ext_rank = len(self.free) + 2*len(self.dum)
self.dum.sort(key=lambda x: x[0])
@staticmethod
def from_indices(*indices):
"""
Create a new ``_IndexStructure`` object from a list of ``indices``
``indices`` ``TensorIndex`` objects, the indices. Contractions are
detected upon construction.
Examples
========
>>> from sympy.tensor.tensor import TensorIndexType, tensor_indices, _IndexStructure
>>> Lorentz = TensorIndexType('Lorentz', dummy_fmt='L')
>>> m0, m1, m2, m3 = tensor_indices('m0,m1,m2,m3', Lorentz)
>>> _IndexStructure.from_indices(m0, m1, -m1, m3)
_IndexStructure([(m0, 0), (m3, 3)], [(1, 2)], [Lorentz, Lorentz, Lorentz, Lorentz])
In case of many components the same indices have slightly different
indexes:
>>> _IndexStructure.from_indices(m0, m1, -m1, m3)
_IndexStructure([(m0, 0), (m3, 3)], [(1, 2)], [Lorentz, Lorentz, Lorentz, Lorentz])
"""
free, dum = _IndexStructure._free_dum_from_indices(*indices)
index_types = [i.tensor_index_type for i in indices]
indices = _IndexStructure._replace_dummy_names(indices, free, dum)
return _IndexStructure(free, dum, index_types, indices)
@staticmethod
def from_components_free_dum(components, free, dum):
index_types = []
for component in components:
index_types.extend(component.index_types)
indices = _IndexStructure.generate_indices_from_free_dum_index_types(free, dum, index_types)
return _IndexStructure(free, dum, index_types, indices)
@staticmethod
def _free_dum_from_indices(*indices):
"""
Convert ``indices`` into ``free``, ``dum`` for single component tensor
``free`` list of tuples ``(index, pos, 0)``,
where ``pos`` is the position of index in
the list of indices formed by the component tensors
``dum`` list of tuples ``(pos_contr, pos_cov, 0, 0)``
Examples
========
>>> from sympy.tensor.tensor import TensorIndexType, tensor_indices, \
_IndexStructure
>>> Lorentz = TensorIndexType('Lorentz', dummy_fmt='L')
>>> m0, m1, m2, m3 = tensor_indices('m0,m1,m2,m3', Lorentz)
>>> _IndexStructure._free_dum_from_indices(m0, m1, -m1, m3)
([(m0, 0), (m3, 3)], [(1, 2)])
"""
n = len(indices)
if n == 1:
return [(indices[0], 0)], []
# find the positions of the free indices and of the dummy indices
free = [True]*len(indices)
index_dict = {}
dum = []
for i, index in enumerate(indices):
name = index._name
typ = index.tensor_index_type
contr = index._is_up
if (name, typ) in index_dict:
# found a pair of dummy indices
is_contr, pos = index_dict[(name, typ)]
# check consistency and update free
if is_contr:
if contr:
raise ValueError('two equal contravariant indices in slots %d and %d' %(pos, i))
else:
free[pos] = False
free[i] = False
else:
if contr:
free[pos] = False
free[i] = False
else:
raise ValueError('two equal covariant indices in slots %d and %d' %(pos, i))
if contr:
dum.append((i, pos))
else:
dum.append((pos, i))
else:
index_dict[(name, typ)] = index._is_up, i
free = [(index, i) for i, index in enumerate(indices) if free[i]]
free.sort()
return free, dum
def get_indices(self):
"""
Get a list of indices, creating new tensor indices to complete dummy indices.
"""
return self.indices[:]
@staticmethod
def generate_indices_from_free_dum_index_types(free, dum, index_types):
indices = [None]*(len(free)+2*len(dum))
for idx, pos in free:
indices[pos] = idx
generate_dummy_name = _IndexStructure._get_generator_for_dummy_indices(free)
for pos1, pos2 in dum:
typ1 = index_types[pos1]
indname = generate_dummy_name(typ1)
indices[pos1] = TensorIndex(indname, typ1, True)
indices[pos2] = TensorIndex(indname, typ1, False)
return _IndexStructure._replace_dummy_names(indices, free, dum)
@staticmethod
def _get_generator_for_dummy_indices(free):
cdt = defaultdict(int)
# if the free indices have names with dummy_fmt, start with an
# index higher than those for the dummy indices
# to avoid name collisions
for indx, ipos in free:
if indx._name.split('_')[0] == indx.tensor_index_type.dummy_fmt[:-3]:
cdt[indx.tensor_index_type] = max(cdt[indx.tensor_index_type], int(indx._name.split('_')[1]) + 1)
def dummy_fmt_gen(tensor_index_type):
fmt = tensor_index_type.dummy_fmt
nd = cdt[tensor_index_type]
cdt[tensor_index_type] += 1
return fmt % nd
return dummy_fmt_gen
@staticmethod
def _replace_dummy_names(indices, free, dum):
dum.sort(key=lambda x: x[0])
new_indices = [ind for ind in indices]
assert len(indices) == len(free) + 2*len(dum)
generate_dummy_name = _IndexStructure._get_generator_for_dummy_indices(free)
for ipos1, ipos2 in dum:
typ1 = new_indices[ipos1].tensor_index_type
indname = generate_dummy_name(typ1)
new_indices[ipos1] = TensorIndex(indname, typ1, True)
new_indices[ipos2] = TensorIndex(indname, typ1, False)
return new_indices
def get_free_indices(self):
"""
Get a list of free indices.
"""
# get sorted indices according to their position:
free = sorted(self.free, key=lambda x: x[1])
return [i[0] for i in free]
def __str__(self):
return "_IndexStructure({0}, {1}, {2})".format(self.free, self.dum, self.index_types)
def __repr__(self):
return self.__str__()
def _get_sorted_free_indices_for_canon(self):
sorted_free = self.free[:]
sorted_free.sort(key=lambda x: x[0])
return sorted_free
def _get_sorted_dum_indices_for_canon(self):
return sorted(self.dum, key=lambda x: x[0])
def _get_lexicographically_sorted_index_types(self):
permutation = self.indices_canon_args()[0]
index_types = [None]*self._ext_rank
for i, it in enumerate(self.index_types):
index_types[permutation(i)] = it
return index_types
def _get_lexicographically_sorted_indices(self):
permutation = self.indices_canon_args()[0]
indices = [None]*self._ext_rank
for i, it in enumerate(self.indices):
indices[permutation(i)] = it
return indices
def perm2tensor(self, g, is_canon_bp=False):
"""
Returns a ``_IndexStructure`` instance corresponding to the permutation ``g``
``g`` permutation corresponding to the tensor in the representation
used in canonicalization
``is_canon_bp`` if True, then ``g`` is the permutation
corresponding to the canonical form of the tensor
"""
sorted_free = [i[0] for i in self._get_sorted_free_indices_for_canon()]
lex_index_types = self._get_lexicographically_sorted_index_types()
lex_indices = self._get_lexicographically_sorted_indices()
nfree = len(sorted_free)
rank = self._ext_rank
dum = [[None]*2 for i in range((rank - nfree)//2)]
free = []
index_types = [None]*rank
indices = [None]*rank
for i in range(rank):
gi = g[i]
index_types[i] = lex_index_types[gi]
indices[i] = lex_indices[gi]
if gi < nfree:
ind = sorted_free[gi]
assert index_types[i] == sorted_free[gi].tensor_index_type
free.append((ind, i))
else:
j = gi - nfree
idum, cov = divmod(j, 2)
if cov:
dum[idum][1] = i
else:
dum[idum][0] = i
dum = [tuple(x) for x in dum]
return _IndexStructure(free, dum, index_types, indices)
def indices_canon_args(self):
"""
Returns ``(g, dummies, msym, v)``, the entries of ``canonicalize``
see ``canonicalize`` in ``tensor_can.py``
"""
# to be called after sorted_components
from sympy.combinatorics.permutations import _af_new
n = self._ext_rank
g = [None]*n + [n, n+1]
# ordered indices: first the free indices, ordered by types
# then the dummy indices, ordered by types and contravariant before
# covariant
# g[position in tensor] = position in ordered indices
for i, (indx, ipos) in enumerate(self._get_sorted_free_indices_for_canon()):
g[ipos] = i
pos = len(self.free)
j = len(self.free)
dummies = []
prev = None
a = []
msym = []
for ipos1, ipos2 in self._get_sorted_dum_indices_for_canon():
g[ipos1] = j
g[ipos2] = j + 1
j += 2
typ = self.index_types[ipos1]
if typ != prev:
if a:
dummies.append(a)
a = [pos, pos + 1]
prev = typ
msym.append(typ.metric_antisym)
else:
a.extend([pos, pos + 1])
pos += 2
if a:
dummies.append(a)
return _af_new(g), dummies, msym
def components_canon_args(components):
numtyp = []
prev = None
for t in components:
if t == prev:
numtyp[-1][1] += 1
else:
prev = t
numtyp.append([prev, 1])
v = []
for h, n in numtyp:
if h._comm == 0 or h._comm == 1:
comm = h._comm
else:
comm = TensorManager.get_comm(h._comm, h._comm)
v.append((h._symmetry.base, h._symmetry.generators, n, comm))
return v
class _TensorDataLazyEvaluator(CantSympify):
"""
EXPERIMENTAL: do not rely on this class, it may change without deprecation
warnings in future versions of SymPy.
This object contains the logic to associate components data to a tensor
expression. Components data are set via the ``.data`` property of tensor
expressions, is stored inside this class as a mapping between the tensor
expression and the ``ndarray``.
Computations are executed lazily: whereas the tensor expressions can have
contractions, tensor products, and additions, components data are not
computed until they are accessed by reading the ``.data`` property
associated to the tensor expression.
"""
_substitutions_dict = dict()
_substitutions_dict_tensmul = dict()
def __getitem__(self, key):
dat = self._get(key)
if dat is None:
return None
from .array import NDimArray
if not isinstance(dat, NDimArray):
return dat
if dat.rank() == 0:
return dat[()]
elif dat.rank() == 1 and len(dat) == 1:
return dat[0]
return dat
def _get(self, key):
"""
Retrieve ``data`` associated with ``key``.
This algorithm looks into ``self._substitutions_dict`` for all
``TensorHead`` in the ``TensExpr`` (or just ``TensorHead`` if key is a
TensorHead instance). It reconstructs the components data that the
tensor expression should have by performing on components data the
operations that correspond to the abstract tensor operations applied.
Metric tensor is handled in a different manner: it is pre-computed in
``self._substitutions_dict_tensmul``.
"""
if key in self._substitutions_dict:
return self._substitutions_dict[key]
if isinstance(key, TensorHead):
return None
if isinstance(key, Tensor):
# special case to handle metrics. Metric tensors cannot be
# constructed through contraction by the metric, their
# components show if they are a matrix or its inverse.
signature = tuple([i.is_up for i in key.get_indices()])
srch = (key.component,) + signature
if srch in self._substitutions_dict_tensmul:
return self._substitutions_dict_tensmul[srch]
array_list = [self.data_from_tensor(key)]
return self.data_contract_dum(array_list, key.dum, key.ext_rank)
if isinstance(key, TensMul):
tensmul_args = key.args
if len(tensmul_args) == 1 and len(tensmul_args[0].components) == 1:
# special case to handle metrics. Metric tensors cannot be
# constructed through contraction by the metric, their
# components show if they are a matrix or its inverse.
signature = tuple([i.is_up for i in tensmul_args[0].get_indices()])
srch = (tensmul_args[0].components[0],) + signature
if srch in self._substitutions_dict_tensmul:
return self._substitutions_dict_tensmul[srch]
#data_list = [self.data_from_tensor(i) for i in tensmul_args if isinstance(i, TensExpr)]
data_list = [self.data_from_tensor(i) if isinstance(i, Tensor) else i.data for i in tensmul_args if isinstance(i, TensExpr)]
coeff = prod([i for i in tensmul_args if not isinstance(i, TensExpr)])
if all([i is None for i in data_list]):
return None
if any([i is None for i in data_list]):
raise ValueError("Mixing tensors with associated components "\
"data with tensors without components data")
data_result = self.data_contract_dum(data_list, key.dum, key.ext_rank)
return coeff*data_result
if isinstance(key, TensAdd):
data_list = []
free_args_list = []
for arg in key.args:
if isinstance(arg, TensExpr):
data_list.append(arg.data)
free_args_list.append([x[0] for x in arg.free])
else:
data_list.append(arg)
free_args_list.append([])
if all([i is None for i in data_list]):
return None
if any([i is None for i in data_list]):
raise ValueError("Mixing tensors with associated components "\
"data with tensors without components data")
sum_list = []
from .array import permutedims
for data, free_args in zip(data_list, free_args_list):
if len(free_args) < 2:
sum_list.append(data)
else:
free_args_pos = {y: x for x, y in enumerate(free_args)}
axes = [free_args_pos[arg] for arg in key.free_args]
sum_list.append(permutedims(data, axes))
return reduce(lambda x, y: x+y, sum_list)
return None
@staticmethod
def data_contract_dum(ndarray_list, dum, ext_rank):
from .array import tensorproduct, tensorcontraction, MutableDenseNDimArray
arrays = list(map(MutableDenseNDimArray, ndarray_list))
prodarr = tensorproduct(*arrays)
return tensorcontraction(prodarr, *dum)
def data_tensorhead_from_tensmul(self, data, tensmul, tensorhead):
"""
This method is used when assigning components data to a ``TensMul``
object, it converts components data to a fully contravariant ndarray,
which is then stored according to the ``TensorHead`` key.
"""
if data is None:
return None
return self._correct_signature_from_indices(
data,
tensmul.get_indices(),
tensmul.free,
tensmul.dum,
True)
def data_from_tensor(self, tensor):
"""
This method corrects the components data to the right signature
(covariant/contravariant) using the metric associated with each
``TensorIndexType``.
"""
tensorhead = tensor.component
if tensorhead.data is None:
return None
return self._correct_signature_from_indices(
tensorhead.data,
tensor.get_indices(),
tensor.free,
tensor.dum)
def _assign_data_to_tensor_expr(self, key, data):
if isinstance(key, TensAdd):
raise ValueError('cannot assign data to TensAdd')
# here it is assumed that `key` is a `TensMul` instance.
if len(key.components) != 1:
raise ValueError('cannot assign data to TensMul with multiple components')
tensorhead = key.components[0]
newdata = self.data_tensorhead_from_tensmul(data, key, tensorhead)
return tensorhead, newdata
def _check_permutations_on_data(self, tens, data):
from .array import permutedims
if isinstance(tens, TensorHead):
rank = tens.rank
generators = tens.symmetry.generators
elif isinstance(tens, Tensor):
rank = tens.rank
generators = tens.components[0].symmetry.generators
elif isinstance(tens, TensorIndexType):
rank = tens.metric.rank
generators = tens.metric.symmetry.generators
# Every generator is a permutation, check that by permuting the array
# by that permutation, the array will be the same, except for a
# possible sign change if the permutation admits it.
for gener in generators:
sign_change = +1 if (gener(rank) == rank) else -1
data_swapped = data
last_data = data
permute_axes = list(map(gener, list(range(rank))))
# the order of a permutation is the number of times to get the
# identity by applying that permutation.
for i in range(gener.order()-1):
data_swapped = permutedims(data_swapped, permute_axes)
# if any value in the difference array is non-zero, raise an error:
if any(last_data - sign_change*data_swapped):
raise ValueError("Component data symmetry structure error")
last_data = data_swapped
def __setitem__(self, key, value):
"""
Set the components data of a tensor object/expression.
Components data are transformed to the all-contravariant form and stored
with the corresponding ``TensorHead`` object. If a ``TensorHead`` object
cannot be uniquely identified, it will raise an error.
"""
data = _TensorDataLazyEvaluator.parse_data(value)
self._check_permutations_on_data(key, data)
# TensorHead and TensorIndexType can be assigned data directly, while
# TensMul must first convert data to a fully contravariant form, and
# assign it to its corresponding TensorHead single component.
if not isinstance(key, (TensorHead, TensorIndexType)):
key, data = self._assign_data_to_tensor_expr(key, data)
if isinstance(key, TensorHead):
for dim, indextype in zip(data.shape, key.index_types):
if indextype.data is None:
raise ValueError("index type {} has no components data"\
" associated (needed to raise/lower index)".format(indextype))
if indextype.dim is None:
continue
if dim != indextype.dim:
raise ValueError("wrong dimension of ndarray")
self._substitutions_dict[key] = data
def __delitem__(self, key):
del self._substitutions_dict[key]
def __contains__(self, key):
return key in self._substitutions_dict
def add_metric_data(self, metric, data):
"""
Assign data to the ``metric`` tensor. The metric tensor behaves in an
anomalous way when raising and lowering indices.
A fully covariant metric is the inverse transpose of the fully
contravariant metric (it is meant matrix inverse). If the metric is
symmetric, the transpose is not necessary and mixed
covariant/contravariant metrics are Kronecker deltas.
"""
# hard assignment, data should not be added to `TensorHead` for metric:
# the problem with `TensorHead` is that the metric is anomalous, i.e.
# raising and lowering the index means considering the metric or its
# inverse, this is not the case for other tensors.
self._substitutions_dict_tensmul[metric, True, True] = data
inverse_transpose = self.inverse_transpose_matrix(data)
# in symmetric spaces, the traspose is the same as the original matrix,
# the full covariant metric tensor is the inverse transpose, so this
# code will be able to handle non-symmetric metrics.
self._substitutions_dict_tensmul[metric, False, False] = inverse_transpose
# now mixed cases, these are identical to the unit matrix if the metric
# is symmetric.
m = data.tomatrix()
invt = inverse_transpose.tomatrix()
self._substitutions_dict_tensmul[metric, True, False] = m * invt
self._substitutions_dict_tensmul[metric, False, True] = invt * m
@staticmethod
def _flip_index_by_metric(data, metric, pos):
from .array import tensorproduct, tensorcontraction
mdim = metric.rank()
ddim = data.rank()
if pos == 0:
data = tensorcontraction(
tensorproduct(
metric,
data
),
(1, mdim+pos)
)
else:
data = tensorcontraction(
tensorproduct(
data,
metric
),
(pos, ddim)
)
return data
@staticmethod
def inverse_matrix(ndarray):
m = ndarray.tomatrix().inv()
return _TensorDataLazyEvaluator.parse_data(m)
@staticmethod
def inverse_transpose_matrix(ndarray):
m = ndarray.tomatrix().inv().T
return _TensorDataLazyEvaluator.parse_data(m)
@staticmethod
def _correct_signature_from_indices(data, indices, free, dum, inverse=False):
"""
Utility function to correct the values inside the components data
ndarray according to whether indices are covariant or contravariant.
It uses the metric matrix to lower values of covariant indices.
"""
# change the ndarray values according covariantness/contravariantness of the indices
# use the metric
for i, indx in enumerate(indices):
if not indx.is_up and not inverse:
data = _TensorDataLazyEvaluator._flip_index_by_metric(data, indx.tensor_index_type.data, i)
elif not indx.is_up and inverse:
data = _TensorDataLazyEvaluator._flip_index_by_metric(
data,
_TensorDataLazyEvaluator.inverse_matrix(indx.tensor_index_type.data),
i
)
return data
@staticmethod
def _sort_data_axes(old, new):
from .array import permutedims
new_data = old.data.copy()
old_free = [i[0] for i in old.free]
new_free = [i[0] for i in new.free]
for i in range(len(new_free)):
for j in range(i, len(old_free)):
if old_free[j] == new_free[i]:
old_free[i], old_free[j] = old_free[j], old_free[i]
new_data = permutedims(new_data, (i, j))
break
return new_data
@staticmethod
def add_rearrange_tensmul_parts(new_tensmul, old_tensmul):
def sorted_compo():
return _TensorDataLazyEvaluator._sort_data_axes(old_tensmul, new_tensmul)
_TensorDataLazyEvaluator._substitutions_dict[new_tensmul] = sorted_compo()
@staticmethod
def parse_data(data):
"""
Transform ``data`` to array. The parameter ``data`` may
contain data in various formats, e.g. nested lists, sympy ``Matrix``,
and so on.
Examples
========
>>> from sympy.tensor.tensor import _TensorDataLazyEvaluator
>>> _TensorDataLazyEvaluator.parse_data([1, 3, -6, 12])
[1, 3, -6, 12]
>>> _TensorDataLazyEvaluator.parse_data([[1, 2], [4, 7]])
[[1, 2], [4, 7]]
"""
from .array import MutableDenseNDimArray
if not isinstance(data, MutableDenseNDimArray):
if len(data) == 2 and hasattr(data[0], '__call__'):
data = MutableDenseNDimArray(data[0], data[1])
else:
data = MutableDenseNDimArray(data)
return data
_tensor_data_substitution_dict = _TensorDataLazyEvaluator()
class _TensorManager(object):
"""
Class to manage tensor properties.
Notes
=====
Tensors belong to tensor commutation groups; each group has a label
``comm``; there are predefined labels:
``0`` tensors commuting with any other tensor
``1`` tensors anticommuting among themselves
``2`` tensors not commuting, apart with those with ``comm=0``
Other groups can be defined using ``set_comm``; tensors in those
groups commute with those with ``comm=0``; by default they
do not commute with any other group.
"""
def __init__(self):
self._comm_init()
def _comm_init(self):
self._comm = [{} for i in range(3)]
for i in range(3):
self._comm[0][i] = 0
self._comm[i][0] = 0
self._comm[1][1] = 1
self._comm[2][1] = None
self._comm[1][2] = None
self._comm_symbols2i = {0:0, 1:1, 2:2}
self._comm_i2symbol = {0:0, 1:1, 2:2}
@property
def comm(self):
return self._comm
def comm_symbols2i(self, i):
"""
get the commutation group number corresponding to ``i``
``i`` can be a symbol or a number or a string
If ``i`` is not already defined its commutation group number
is set.
"""
if i not in self._comm_symbols2i:
n = len(self._comm)
self._comm.append({})
self._comm[n][0] = 0
self._comm[0][n] = 0
self._comm_symbols2i[i] = n
self._comm_i2symbol[n] = i
return n
return self._comm_symbols2i[i]
def comm_i2symbol(self, i):
"""
Returns the symbol corresponding to the commutation group number.
"""
return self._comm_i2symbol[i]
def set_comm(self, i, j, c):
"""
set the commutation parameter ``c`` for commutation groups ``i, j``
Parameters
==========
i, j : symbols representing commutation groups
c : group commutation number
Notes
=====
``i, j`` can be symbols, strings or numbers,
apart from ``0, 1`` and ``2`` which are reserved respectively
for commuting, anticommuting tensors and tensors not commuting
with any other group apart with the commuting tensors.
For the remaining cases, use this method to set the commutation rules;
by default ``c=None``.
The group commutation number ``c`` is assigned in correspondence
to the group commutation symbols; it can be
0 commuting
1 anticommuting
None no commutation property
Examples
========
``G`` and ``GH`` do not commute with themselves and commute with
each other; A is commuting.
>>> from sympy.tensor.tensor import TensorIndexType, tensor_indices, tensorhead, TensorManager
>>> Lorentz = TensorIndexType('Lorentz')
>>> i0,i1,i2,i3,i4 = tensor_indices('i0:5', Lorentz)
>>> A = tensorhead('A', [Lorentz], [[1]])
>>> G = tensorhead('G', [Lorentz], [[1]], 'Gcomm')
>>> GH = tensorhead('GH', [Lorentz], [[1]], 'GHcomm')
>>> TensorManager.set_comm('Gcomm', 'GHcomm', 0)
>>> (GH(i1)*G(i0)).canon_bp()
G(i0)*GH(i1)
>>> (G(i1)*G(i0)).canon_bp()
G(i1)*G(i0)
>>> (G(i1)*A(i0)).canon_bp()
A(i0)*G(i1)
"""
if c not in (0, 1, None):
raise ValueError('`c` can assume only the values 0, 1 or None')
if i not in self._comm_symbols2i:
n = len(self._comm)
self._comm.append({})
self._comm[n][0] = 0
self._comm[0][n] = 0
self._comm_symbols2i[i] = n
self._comm_i2symbol[n] = i
if j not in self._comm_symbols2i:
n = len(self._comm)
self._comm.append({})
self._comm[0][n] = 0
self._comm[n][0] = 0
self._comm_symbols2i[j] = n
self._comm_i2symbol[n] = j
ni = self._comm_symbols2i[i]
nj = self._comm_symbols2i[j]
self._comm[ni][nj] = c
self._comm[nj][ni] = c
def set_comms(self, *args):
"""
set the commutation group numbers ``c`` for symbols ``i, j``
Parameters
==========
args : sequence of ``(i, j, c)``
"""
for i, j, c in args:
self.set_comm(i, j, c)
def get_comm(self, i, j):
"""
Return the commutation parameter for commutation group numbers ``i, j``
see ``_TensorManager.set_comm``
"""
return self._comm[i].get(j, 0 if i == 0 or j == 0 else None)
def clear(self):
"""
Clear the TensorManager.
"""
self._comm_init()
TensorManager = _TensorManager()
class TensorIndexType(Basic):
"""
A TensorIndexType is characterized by its name and its metric.
Parameters
==========
name : name of the tensor type
metric : metric symmetry or metric object or ``None``
dim : dimension, it can be a symbol or an integer or ``None``
eps_dim : dimension of the epsilon tensor
dummy_fmt : name of the head of dummy indices
Attributes
==========
``name``
``metric_name`` : it is 'metric' or metric.name
``metric_antisym``
``metric`` : the metric tensor
``delta`` : ``Kronecker delta``
``epsilon`` : the ``Levi-Civita epsilon`` tensor
``dim``
``eps_dim``
``dummy_fmt``
``data`` : a property to add ``ndarray`` values, to work in a specified basis.
Notes
=====
The ``metric`` parameter can be:
``metric = False`` symmetric metric (in Riemannian geometry)
``metric = True`` antisymmetric metric (for spinor calculus)
``metric = None`` there is no metric
``metric`` can be an object having ``name`` and ``antisym`` attributes.
If there is a metric the metric is used to raise and lower indices.
In the case of antisymmetric metric, the following raising and
lowering conventions will be adopted:
``psi(a) = g(a, b)*psi(-b); chi(-a) = chi(b)*g(-b, -a)``
``g(-a, b) = delta(-a, b); g(b, -a) = -delta(a, -b)``
where ``delta(-a, b) = delta(b, -a)`` is the ``Kronecker delta``
(see ``TensorIndex`` for the conventions on indices).
If there is no metric it is not possible to raise or lower indices;
e.g. the index of the defining representation of ``SU(N)``
is 'covariant' and the conjugate representation is
'contravariant'; for ``N > 2`` they are linearly independent.
``eps_dim`` is by default equal to ``dim``, if the latter is an integer;
else it can be assigned (for use in naive dimensional regularization);
if ``eps_dim`` is not an integer ``epsilon`` is ``None``.
Examples
========
>>> from sympy.tensor.tensor import TensorIndexType
>>> Lorentz = TensorIndexType('Lorentz', dummy_fmt='L')
>>> Lorentz.metric
metric(Lorentz,Lorentz)
"""
def __new__(cls, name, metric=False, dim=None, eps_dim=None,
dummy_fmt=None):
if isinstance(name, string_types):
name = Symbol(name)
obj = Basic.__new__(cls, name, S.One if metric else S.Zero)
obj._name = str(name)
if not dummy_fmt:
obj._dummy_fmt = '%s_%%d' % obj.name
else:
obj._dummy_fmt = '%s_%%d' % dummy_fmt
if metric is None:
obj.metric_antisym = None
obj.metric = None
else:
if metric in (True, False, 0, 1):
metric_name = 'metric'
obj.metric_antisym = metric
else:
metric_name = metric.name
obj.metric_antisym = metric.antisym
sym2 = TensorSymmetry(get_symmetric_group_sgs(2, obj.metric_antisym))
S2 = TensorType([obj]*2, sym2)
obj.metric = S2(metric_name)
obj._dim = dim
obj._delta = obj.get_kronecker_delta()
obj._eps_dim = eps_dim if eps_dim else dim
obj._epsilon = obj.get_epsilon()
obj._autogenerated = []
return obj
@property
@deprecated(useinstead="TensorIndex", issue=12857, deprecated_since_version="1.1")
def auto_right(self):
if not hasattr(self, '_auto_right'):
self._auto_right = TensorIndex("auto_right", self)
return self._auto_right
@property
@deprecated(useinstead="TensorIndex", issue=12857, deprecated_since_version="1.1")
def auto_left(self):
if not hasattr(self, '_auto_left'):
self._auto_left = TensorIndex("auto_left", self)
return self._auto_left
@property
@deprecated(useinstead="TensorIndex", issue=12857, deprecated_since_version="1.1")
def auto_index(self):
if not hasattr(self, '_auto_index'):
self._auto_index = TensorIndex("auto_index", self)
return self._auto_index
@property
def data(self):
deprecate_data()
return _tensor_data_substitution_dict[self]
@data.setter
def data(self, data):
deprecate_data()
# This assignment is a bit controversial, should metric components be assigned
# to the metric only or also to the TensorIndexType object? The advantage here
# is the ability to assign a 1D array and transform it to a 2D diagonal array.
from .array import MutableDenseNDimArray
data = _TensorDataLazyEvaluator.parse_data(data)
if data.rank() > 2:
raise ValueError("data have to be of rank 1 (diagonal metric) or 2.")
if data.rank() == 1:
if self.dim is not None:
nda_dim = data.shape[0]
if nda_dim != self.dim:
raise ValueError("Dimension mismatch")
dim = data.shape[0]
newndarray = MutableDenseNDimArray.zeros(dim, dim)
for i, val in enumerate(data):
newndarray[i, i] = val
data = newndarray
dim1, dim2 = data.shape
if dim1 != dim2:
raise ValueError("Non-square matrix tensor.")
if self.dim is not None:
if self.dim != dim1:
raise ValueError("Dimension mismatch")
_tensor_data_substitution_dict[self] = data
_tensor_data_substitution_dict.add_metric_data(self.metric, data)
delta = self.get_kronecker_delta()
i1 = TensorIndex('i1', self)
i2 = TensorIndex('i2', self)
delta(i1, -i2).data = _TensorDataLazyEvaluator.parse_data(eye(dim1))
@data.deleter
def data(self):
deprecate_data()
if self in _tensor_data_substitution_dict:
del _tensor_data_substitution_dict[self]
if self.metric in _tensor_data_substitution_dict:
del _tensor_data_substitution_dict[self.metric]
def _get_matrix_fmt(self, number):
return ("m" + self.dummy_fmt) % (number)
@property
def name(self):
return self._name
@property
def dim(self):
return self._dim
@property
def delta(self):
return self._delta
@property
def eps_dim(self):
return self._eps_dim
@property
def epsilon(self):
return self._epsilon
@property
def dummy_fmt(self):
return self._dummy_fmt
def get_kronecker_delta(self):
sym2 = TensorSymmetry(get_symmetric_group_sgs(2))
S2 = TensorType([self]*2, sym2)
delta = S2('KD')
return delta
def get_epsilon(self):
if not isinstance(self._eps_dim, (SYMPY_INTS, Integer)):
return None
sym = TensorSymmetry(get_symmetric_group_sgs(self._eps_dim, 1))
Sdim = TensorType([self]*self._eps_dim, sym)
epsilon = Sdim('Eps')
return epsilon
def __lt__(self, other):
return self.name < other.name
def __str__(self):
return self.name
__repr__ = __str__
def _components_data_full_destroy(self):
"""
EXPERIMENTAL: do not rely on this API method.
This destroys components data associated to the ``TensorIndexType``, if
any, specifically:
* metric tensor data
* Kronecker tensor data
"""
if self in _tensor_data_substitution_dict:
del _tensor_data_substitution_dict[self]
def delete_tensmul_data(key):
if key in _tensor_data_substitution_dict._substitutions_dict_tensmul:
del _tensor_data_substitution_dict._substitutions_dict_tensmul[key]
# delete metric data:
delete_tensmul_data((self.metric, True, True))
delete_tensmul_data((self.metric, True, False))
delete_tensmul_data((self.metric, False, True))
delete_tensmul_data((self.metric, False, False))
# delete delta tensor data:
delta = self.get_kronecker_delta()
if delta in _tensor_data_substitution_dict:
del _tensor_data_substitution_dict[delta]
class TensorIndex(Basic):
"""
Represents an abstract tensor index.
Parameters
==========
name : name of the index, or ``True`` if you want it to be automatically assigned
tensortype : ``TensorIndexType`` of the index
is_up : flag for contravariant index
Attributes
==========
``name``
``tensortype``
``is_up``
Notes
=====
Tensor indices are contracted with the Einstein summation convention.
An index can be in contravariant or in covariant form; in the latter
case it is represented prepending a ``-`` to the index name.
Dummy indices have a name with head given by ``tensortype._dummy_fmt``
Examples
========
>>> from sympy.tensor.tensor import TensorIndexType, TensorIndex, TensorSymmetry, TensorType, get_symmetric_group_sgs
>>> Lorentz = TensorIndexType('Lorentz', dummy_fmt='L')
>>> i = TensorIndex('i', Lorentz); i
i
>>> sym1 = TensorSymmetry(*get_symmetric_group_sgs(1))
>>> S1 = TensorType([Lorentz], sym1)
>>> A, B = S1('A,B')
>>> A(i)*B(-i)
A(L_0)*B(-L_0)
If you want the index name to be automatically assigned, just put ``True``
in the ``name`` field, it will be generated using the reserved character
``_`` in front of its name, in order to avoid conflicts with possible
existing indices:
>>> i0 = TensorIndex(True, Lorentz)
>>> i0
_i0
>>> i1 = TensorIndex(True, Lorentz)
>>> i1
_i1
>>> A(i0)*B(-i1)
A(_i0)*B(-_i1)
>>> A(i0)*B(-i0)
A(L_0)*B(-L_0)
"""
def __new__(cls, name, tensortype, is_up=True):
if isinstance(name, string_types):
name_symbol = Symbol(name)
elif isinstance(name, Symbol):
name_symbol = name
elif name is True:
name = "_i{0}".format(len(tensortype._autogenerated))
name_symbol = Symbol(name)
tensortype._autogenerated.append(name_symbol)
else:
raise ValueError("invalid name")
is_up = sympify(is_up)
obj = Basic.__new__(cls, name_symbol, tensortype, is_up)
obj._name = str(name)
obj._tensor_index_type = tensortype
obj._is_up = is_up
return obj
@property
def name(self):
return self._name
@property
@deprecated(useinstead="tensor_index_type", issue=12857, deprecated_since_version="1.1")
def tensortype(self):
return self.tensor_index_type
@property
def tensor_index_type(self):
return self._tensor_index_type
@property
def is_up(self):
return self._is_up
def _print(self):
s = self._name
if not self._is_up:
s = '-%s' % s
return s
def __lt__(self, other):
return (self.tensor_index_type, self._name) < (other.tensor_index_type, other._name)
def __neg__(self):
t1 = TensorIndex(self.name, self.tensor_index_type,
(not self.is_up))
return t1
def tensor_indices(s, typ):
"""
Returns list of tensor indices given their names and their types
Parameters
==========
s : string of comma separated names of indices
typ : ``TensorIndexType`` of the indices
Examples
========
>>> from sympy.tensor.tensor import TensorIndexType, tensor_indices
>>> Lorentz = TensorIndexType('Lorentz', dummy_fmt='L')
>>> a, b, c, d = tensor_indices('a,b,c,d', Lorentz)
"""
if isinstance(s, str):
a = [x.name for x in symbols(s, seq=True)]
else:
raise ValueError('expecting a string')
tilist = [TensorIndex(i, typ) for i in a]
if len(tilist) == 1:
return tilist[0]
return tilist
class TensorSymmetry(Basic):
"""
Monoterm symmetry of a tensor
Parameters
==========
bsgs : tuple ``(base, sgs)`` BSGS of the symmetry of the tensor
Attributes
==========
``base`` : base of the BSGS
``generators`` : generators of the BSGS
``rank`` : rank of the tensor
Notes
=====
A tensor can have an arbitrary monoterm symmetry provided by its BSGS.
Multiterm symmetries, like the cyclic symmetry of the Riemann tensor,
are not covered.
See Also
========
sympy.combinatorics.tensor_can.get_symmetric_group_sgs
Examples
========
Define a symmetric tensor
>>> from sympy.tensor.tensor import TensorIndexType, TensorSymmetry, TensorType, get_symmetric_group_sgs
>>> Lorentz = TensorIndexType('Lorentz', dummy_fmt='L')
>>> sym2 = TensorSymmetry(get_symmetric_group_sgs(2))
>>> S2 = TensorType([Lorentz]*2, sym2)
>>> V = S2('V')
"""
def __new__(cls, *args, **kw_args):
if len(args) == 1:
base, generators = args[0]
elif len(args) == 2:
base, generators = args
else:
raise TypeError("bsgs required, either two separate parameters or one tuple")
if not isinstance(base, Tuple):
base = Tuple(*base)
if not isinstance(generators, Tuple):
generators = Tuple(*generators)
obj = Basic.__new__(cls, base, generators, **kw_args)
return obj
@property
def base(self):
return self.args[0]
@property
def generators(self):
return self.args[1]
@property
def rank(self):
return self.args[1][0].size - 2
def tensorsymmetry(*args):
"""
Return a ``TensorSymmetry`` object.
One can represent a tensor with any monoterm slot symmetry group
using a BSGS.
``args`` can be a BSGS
``args[0]`` base
``args[1]`` sgs
Usually tensors are in (direct products of) representations
of the symmetric group;
``args`` can be a list of lists representing the shapes of Young tableaux
Notes
=====
For instance:
``[[1]]`` vector
``[[1]*n]`` symmetric tensor of rank ``n``
``[[n]]`` antisymmetric tensor of rank ``n``
``[[2, 2]]`` monoterm slot symmetry of the Riemann tensor
``[[1],[1]]`` vector*vector
``[[2],[1],[1]`` (antisymmetric tensor)*vector*vector
Notice that with the shape ``[2, 2]`` we associate only the monoterm
symmetries of the Riemann tensor; this is an abuse of notation,
since the shape ``[2, 2]`` corresponds usually to the irreducible
representation characterized by the monoterm symmetries and by the
cyclic symmetry.
Examples
========
Symmetric tensor using a Young tableau
>>> from sympy.tensor.tensor import TensorIndexType, TensorType, tensorsymmetry
>>> Lorentz = TensorIndexType('Lorentz', dummy_fmt='L')
>>> sym2 = tensorsymmetry([1, 1])
>>> S2 = TensorType([Lorentz]*2, sym2)
>>> V = S2('V')
Symmetric tensor using a ``BSGS`` (base, strong generator set)
>>> from sympy.tensor.tensor import get_symmetric_group_sgs
>>> sym2 = tensorsymmetry(*get_symmetric_group_sgs(2))
>>> S2 = TensorType([Lorentz]*2, sym2)
>>> V = S2('V')
"""
from sympy.combinatorics import Permutation
def tableau2bsgs(a):
if len(a) == 1:
# antisymmetric vector
n = a[0]
bsgs = get_symmetric_group_sgs(n, 1)
else:
if all(x == 1 for x in a):
# symmetric vector
n = len(a)
bsgs = get_symmetric_group_sgs(n)
elif a == [2, 2]:
bsgs = riemann_bsgs
else:
raise NotImplementedError
return bsgs
if not args:
return TensorSymmetry(Tuple(), Tuple(Permutation(1)))
if len(args) == 2 and isinstance(args[1][0], Permutation):
return TensorSymmetry(args)
base, sgs = tableau2bsgs(args[0])
for a in args[1:]:
basex, sgsx = tableau2bsgs(a)
base, sgs = bsgs_direct_product(base, sgs, basex, sgsx)
return TensorSymmetry(Tuple(base, sgs))
class TensorType(Basic):
"""
Class of tensor types.
Parameters
==========
index_types : list of ``TensorIndexType`` of the tensor indices
symmetry : ``TensorSymmetry`` of the tensor
Attributes
==========
``index_types``
``symmetry``
``types`` : list of ``TensorIndexType`` without repetitions
Examples
========
Define a symmetric tensor
>>> from sympy.tensor.tensor import TensorIndexType, tensorsymmetry, TensorType
>>> Lorentz = TensorIndexType('Lorentz', dummy_fmt='L')
>>> sym2 = tensorsymmetry([1, 1])
>>> S2 = TensorType([Lorentz]*2, sym2)
>>> V = S2('V')
"""
is_commutative = False
def __new__(cls, index_types, symmetry, **kw_args):
assert symmetry.rank == len(index_types)
obj = Basic.__new__(cls, Tuple(*index_types), symmetry, **kw_args)
return obj
@property
def index_types(self):
return self.args[0]
@property
def symmetry(self):
return self.args[1]
@property
def types(self):
return sorted(set(self.index_types), key=lambda x: x.name)
def __str__(self):
return 'TensorType(%s)' % ([str(x) for x in self.index_types])
def __call__(self, s, comm=0):
"""
Return a TensorHead object or a list of TensorHead objects.
``s`` name or string of names
``comm``: commutation group number
see ``_TensorManager.set_comm``
Examples
========
Define symmetric tensors ``V``, ``W`` and ``G``, respectively
commuting, anticommuting and with no commutation symmetry
>>> from sympy.tensor.tensor import TensorIndexType, tensor_indices, tensorsymmetry, TensorType, canon_bp
>>> Lorentz = TensorIndexType('Lorentz', dummy_fmt='L')
>>> a, b = tensor_indices('a,b', Lorentz)
>>> sym2 = tensorsymmetry([1]*2)
>>> S2 = TensorType([Lorentz]*2, sym2)
>>> V = S2('V')
>>> W = S2('W', 1)
>>> G = S2('G', 2)
>>> canon_bp(V(a, b)*V(-b, -a))
V(L_0, L_1)*V(-L_0, -L_1)
>>> canon_bp(W(a, b)*W(-b, -a))
0
"""
if isinstance(s, str):
names = [x.name for x in symbols(s, seq=True)]
else:
raise ValueError('expecting a string')
if len(names) == 1:
return TensorHead(names[0], self, comm)
else:
return [TensorHead(name, self, comm) for name in names]
def tensorhead(name, typ, sym=None, comm=0):
"""
Function generating tensorhead(s).
Parameters
==========
name : name or sequence of names (as in ``symbol``)
typ : index types
sym : same as ``*args`` in ``tensorsymmetry``
comm : commutation group number
see ``_TensorManager.set_comm``
Examples
========
>>> from sympy.tensor.tensor import TensorIndexType, tensor_indices, tensorhead
>>> Lorentz = TensorIndexType('Lorentz', dummy_fmt='L')
>>> a, b = tensor_indices('a,b', Lorentz)
>>> A = tensorhead('A', [Lorentz]*2, [[1]*2])
>>> A(a, -b)
A(a, -b)
If no symmetry parameter is provided, assume there are not index
symmetries:
>>> B = tensorhead('B', [Lorentz, Lorentz])
>>> B(a, -b)
B(a, -b)
"""
if sym is None:
sym = [[1] for i in range(len(typ))]
sym = tensorsymmetry(*sym)
S = TensorType(typ, sym)
th = S(name, comm)
return th
class TensorHead(Basic):
r"""
Tensor head of the tensor
Parameters
==========
name : name of the tensor
typ : list of TensorIndexType
comm : commutation group number
Attributes
==========
``name``
``index_types``
``rank``
``types`` : equal to ``typ.types``
``symmetry`` : equal to ``typ.symmetry``
``comm`` : commutation group
Notes
=====
A ``TensorHead`` belongs to a commutation group, defined by a
symbol on number ``comm`` (see ``_TensorManager.set_comm``);
tensors in a commutation group have the same commutation properties;
by default ``comm`` is ``0``, the group of the commuting tensors.
Examples
========
>>> from sympy.tensor.tensor import TensorIndexType, tensorhead, TensorType
>>> Lorentz = TensorIndexType('Lorentz', dummy_fmt='L')
>>> A = tensorhead('A', [Lorentz, Lorentz], [[1],[1]])
Examples with ndarray values, the components data assigned to the
``TensorHead`` object are assumed to be in a fully-contravariant
representation. In case it is necessary to assign components data which
represents the values of a non-fully covariant tensor, see the other
examples.
>>> from sympy.tensor.tensor import tensor_indices, tensorhead
>>> from sympy import diag
>>> i0, i1 = tensor_indices('i0:2', Lorentz)
Specify a replacement dictionary to keep track of the arrays to use for
replacements in the tensorial expression. The ``TensorIndexType`` is
associated to the metric used for contractions (in fully covariant form):
>>> repl = {Lorentz: diag(1, -1, -1, -1)}
Let's see some examples of working with components with the electromagnetic
tensor:
>>> from sympy import symbols
>>> Ex, Ey, Ez, Bx, By, Bz = symbols('E_x E_y E_z B_x B_y B_z')
>>> c = symbols('c', positive=True)
Let's define `F`, an antisymmetric tensor, we have to assign an
antisymmetric matrix to it, because `[[2]]` stands for the Young tableau
representation of an antisymmetric set of two elements:
>>> F = tensorhead('F', [Lorentz, Lorentz], [[2]])
Let's update the dictionary to contain the matrix to use in the
replacements:
>>> repl.update({F(-i0, -i1): [
... [0, Ex/c, Ey/c, Ez/c],
... [-Ex/c, 0, -Bz, By],
... [-Ey/c, Bz, 0, -Bx],
... [-Ez/c, -By, Bx, 0]]})
Now it is possible to retrieve the contravariant form of the Electromagnetic
tensor:
>>> F(i0, i1).replace_with_arrays(repl, [i0, i1])
[[0, -E_x/c, -E_y/c, -E_z/c], [E_x/c, 0, -B_z, B_y], [E_y/c, B_z, 0, -B_x], [E_z/c, -B_y, B_x, 0]]
and the mixed contravariant-covariant form:
>>> F(i0, -i1).replace_with_arrays(repl, [i0, -i1])
[[0, E_x/c, E_y/c, E_z/c], [E_x/c, 0, B_z, -B_y], [E_y/c, -B_z, 0, B_x], [E_z/c, B_y, -B_x, 0]]
Energy-momentum of a particle may be represented as:
>>> from sympy import symbols
>>> P = tensorhead('P', [Lorentz], [[1]])
>>> E, px, py, pz = symbols('E p_x p_y p_z', positive=True)
>>> repl.update({P(i0): [E, px, py, pz]})
The contravariant and covariant components are, respectively:
>>> P(i0).replace_with_arrays(repl, [i0])
[E, p_x, p_y, p_z]
>>> P(-i0).replace_with_arrays(repl, [-i0])
[E, -p_x, -p_y, -p_z]
The contraction of a 1-index tensor by itself:
>>> expr = P(i0)*P(-i0)
>>> expr.replace_with_arrays(repl, [])
E**2 - p_x**2 - p_y**2 - p_z**2
"""
is_commutative = False
def __new__(cls, name, typ, comm=0, **kw_args):
if isinstance(name, string_types):
name_symbol = Symbol(name)
elif isinstance(name, Symbol):
name_symbol = name
else:
raise ValueError("invalid name")
comm2i = TensorManager.comm_symbols2i(comm)
obj = Basic.__new__(cls, name_symbol, typ, **kw_args)
obj._name = obj.args[0].name
obj._rank = len(obj.index_types)
obj._symmetry = typ.symmetry
obj._comm = comm2i
return obj
@property
def name(self):
return self._name
@property
def rank(self):
return self._rank
@property
def symmetry(self):
return self._symmetry
@property
def typ(self):
return self.args[1]
@property
def comm(self):
return self._comm
@property
def types(self):
return self.args[1].types[:]
@property
def index_types(self):
return self.args[1].index_types[:]
def __lt__(self, other):
return (self.name, self.index_types) < (other.name, other.index_types)
def commutes_with(self, other):
"""
Returns ``0`` if ``self`` and ``other`` commute, ``1`` if they anticommute.
Returns ``None`` if ``self`` and ``other`` neither commute nor anticommute.
"""
r = TensorManager.get_comm(self._comm, other._comm)
return r
def _print(self):
return '%s(%s)' %(self.name, ','.join([str(x) for x in self.index_types]))
def __call__(self, *indices, **kw_args):
"""
Returns a tensor with indices.
There is a special behavior in case of indices denoted by ``True``,
they are considered auto-matrix indices, their slots are automatically
filled, and confer to the tensor the behavior of a matrix or vector
upon multiplication with another tensor containing auto-matrix indices
of the same ``TensorIndexType``. This means indices get summed over the
same way as in matrix multiplication. For matrix behavior, define two
auto-matrix indices, for vector behavior define just one.
Examples
========
>>> from sympy.tensor.tensor import TensorIndexType, tensor_indices, tensorhead
>>> Lorentz = TensorIndexType('Lorentz', dummy_fmt='L')
>>> a, b = tensor_indices('a,b', Lorentz)
>>> A = tensorhead('A', [Lorentz]*2, [[1]*2])
>>> t = A(a, -b)
>>> t
A(a, -b)
"""
tensor = Tensor(self, indices, **kw_args)
return tensor.doit()
def __pow__(self, other):
with warnings.catch_warnings():
warnings.filterwarnings("ignore", category=SymPyDeprecationWarning)
if self.data is None:
raise ValueError("No power on abstract tensors.")
deprecate_data()
from .array import tensorproduct, tensorcontraction
metrics = [_.data for _ in self.args[1].args[0]]
marray = self.data
marraydim = marray.rank()
for metric in metrics:
marray = tensorproduct(marray, metric, marray)
marray = tensorcontraction(marray, (0, marraydim), (marraydim+1, marraydim+2))
return marray ** (Rational(1, 2) * other)
@property
def data(self):
deprecate_data()
return _tensor_data_substitution_dict[self]
@data.setter
def data(self, data):
deprecate_data()
_tensor_data_substitution_dict[self] = data
@data.deleter
def data(self):
deprecate_data()
if self in _tensor_data_substitution_dict:
del _tensor_data_substitution_dict[self]
def __iter__(self):
deprecate_data()
return self.data.__iter__()
def _components_data_full_destroy(self):
"""
EXPERIMENTAL: do not rely on this API method.
Destroy components data associated to the ``TensorHead`` object, this
checks for attached components data, and destroys components data too.
"""
# do not garbage collect Kronecker tensor (it should be done by
# ``TensorIndexType`` garbage collection)
if self.name == "KD":
return
# the data attached to a tensor must be deleted only by the TensorHead
# destructor. If the TensorHead is deleted, it means that there are no
# more instances of that tensor anywhere.
if self in _tensor_data_substitution_dict:
del _tensor_data_substitution_dict[self]
def _get_argtree_pos(expr, pos):
for p in pos:
expr = expr.args[p]
return expr
class TensExpr(Expr):
"""
Abstract base class for tensor expressions
Notes
=====
A tensor expression is an expression formed by tensors;
currently the sums of tensors are distributed.
A ``TensExpr`` can be a ``TensAdd`` or a ``TensMul``.
``TensAdd`` objects are put in canonical form using the Butler-Portugal
algorithm for canonicalization under monoterm symmetries.
``TensMul`` objects are formed by products of component tensors,
and include a coefficient, which is a SymPy expression.
In the internal representation contracted indices are represented
by ``(ipos1, ipos2, icomp1, icomp2)``, where ``icomp1`` is the position
of the component tensor with contravariant index, ``ipos1`` is the
slot which the index occupies in that component tensor.
Contracted indices are therefore nameless in the internal representation.
"""
_op_priority = 12.0
is_commutative = False
def __neg__(self):
return self*S.NegativeOne
def __abs__(self):
raise NotImplementedError
def __add__(self, other):
return TensAdd(self, other).doit()
def __radd__(self, other):
return TensAdd(other, self).doit()
def __sub__(self, other):
return TensAdd(self, -other).doit()
def __rsub__(self, other):
return TensAdd(other, -self).doit()
def __mul__(self, other):
"""
Multiply two tensors using Einstein summation convention.
If the two tensors have an index in common, one contravariant
and the other covariant, in their product the indices are summed
Examples
========
>>> from sympy.tensor.tensor import TensorIndexType, tensor_indices, tensorhead
>>> Lorentz = TensorIndexType('Lorentz', dummy_fmt='L')
>>> m0, m1, m2 = tensor_indices('m0,m1,m2', Lorentz)
>>> g = Lorentz.metric
>>> p, q = tensorhead('p,q', [Lorentz], [[1]])
>>> t1 = p(m0)
>>> t2 = q(-m0)
>>> t1*t2
p(L_0)*q(-L_0)
"""
return TensMul(self, other).doit()
def __rmul__(self, other):
return TensMul(other, self).doit()
def __div__(self, other):
other = _sympify(other)
if isinstance(other, TensExpr):
raise ValueError('cannot divide by a tensor')
return TensMul(self, S.One/other).doit()
def __rdiv__(self, other):
raise ValueError('cannot divide by a tensor')
def __pow__(self, other):
with warnings.catch_warnings():
warnings.filterwarnings("ignore", category=SymPyDeprecationWarning)
if self.data is None:
raise ValueError("No power without ndarray data.")
deprecate_data()
from .array import tensorproduct, tensorcontraction
free = self.free
marray = self.data
mdim = marray.rank()
for metric in free:
marray = tensorcontraction(
tensorproduct(
marray,
metric[0].tensor_index_type.data,
marray),
(0, mdim), (mdim+1, mdim+2)
)
return marray ** (Rational(1, 2) * other)
def __rpow__(self, other):
raise NotImplementedError
__truediv__ = __div__
__rtruediv__ = __rdiv__
def fun_eval(self, *index_tuples):
"""
Return a tensor with free indices substituted according to ``index_tuples``
``index_types`` list of tuples ``(old_index, new_index)``
Examples
========
>>> from sympy.tensor.tensor import TensorIndexType, tensor_indices, tensorhead
>>> Lorentz = TensorIndexType('Lorentz', dummy_fmt='L')
>>> i, j, k, l = tensor_indices('i,j,k,l', Lorentz)
>>> A, B = tensorhead('A,B', [Lorentz]*2, [[1]*2])
>>> t = A(i, k)*B(-k, -j); t
A(i, L_0)*B(-L_0, -j)
>>> t.fun_eval((i, k),(-j, l))
A(k, L_0)*B(-L_0, l)
"""
expr = self.xreplace(dict(index_tuples))
expr = expr.replace(lambda x: isinstance(x, Tensor), lambda x: x.args[0](*x.args[1]))
# For some reason, `TensMul` gets replaced by `Mul`, correct it:
expr = expr.replace(lambda x: isinstance(x, (Mul, TensMul)), lambda x: TensMul(*x.args).doit())
return expr
def get_matrix(self):
"""
DEPRECATED: do not use.
Returns ndarray components data as a matrix, if components data are
available and ndarray dimension does not exceed 2.
"""
from sympy import Matrix
deprecate_data()
if 0 < self.rank <= 2:
rows = self.data.shape[0]
columns = self.data.shape[1] if self.rank == 2 else 1
if self.rank == 2:
mat_list = [] * rows
for i in range(rows):
mat_list.append([])
for j in range(columns):
mat_list[i].append(self[i, j])
else:
mat_list = [None] * rows
for i in range(rows):
mat_list[i] = self[i]
return Matrix(mat_list)
else:
raise NotImplementedError(
"missing multidimensional reduction to matrix.")
@staticmethod
def _get_indices_permutation(indices1, indices2):
return [indices1.index(i) for i in indices2]
def expand(self, **hints):
return _expand(self, **hints).doit()
def _expand(self, **kwargs):
return self
def _get_free_indices_set(self):
indset = set([])
for arg in self.args:
if isinstance(arg, TensExpr):
indset.update(arg._get_free_indices_set())
return indset
def _get_dummy_indices_set(self):
indset = set([])
for arg in self.args:
if isinstance(arg, TensExpr):
indset.update(arg._get_dummy_indices_set())
return indset
def _get_indices_set(self):
indset = set([])
for arg in self.args:
if isinstance(arg, TensExpr):
indset.update(arg._get_indices_set())
return indset
@property
def _iterate_dummy_indices(self):
dummy_set = self._get_dummy_indices_set()
def recursor(expr, pos):
if isinstance(expr, TensorIndex):
if expr in dummy_set:
yield (expr, pos)
elif isinstance(expr, (Tuple, TensExpr)):
for p, arg in enumerate(expr.args):
for i in recursor(arg, pos+(p,)):
yield i
return recursor(self, ())
@property
def _iterate_free_indices(self):
free_set = self._get_free_indices_set()
def recursor(expr, pos):
if isinstance(expr, TensorIndex):
if expr in free_set:
yield (expr, pos)
elif isinstance(expr, (Tuple, TensExpr)):
for p, arg in enumerate(expr.args):
for i in recursor(arg, pos+(p,)):
yield i
return recursor(self, ())
@property
def _iterate_indices(self):
def recursor(expr, pos):
if isinstance(expr, TensorIndex):
yield (expr, pos)
elif isinstance(expr, (Tuple, TensExpr)):
for p, arg in enumerate(expr.args):
for i in recursor(arg, pos+(p,)):
yield i
return recursor(self, ())
@staticmethod
def _match_indices_with_other_tensor(array, free_ind1, free_ind2, replacement_dict):
from .array import tensorcontraction, tensorproduct, permutedims
index_types1 = [i.tensor_index_type for i in free_ind1]
# Check if variance of indices needs to be fixed:
pos2up = []
pos2down = []
free2remaining = free_ind2[:]
for pos1, index1 in enumerate(free_ind1):
if index1 in free2remaining:
pos2 = free2remaining.index(index1)
free2remaining[pos2] = None
continue
if -index1 in free2remaining:
pos2 = free2remaining.index(-index1)
free2remaining[pos2] = None
free_ind2[pos2] = index1
if index1.is_up:
pos2up.append(pos2)
else:
pos2down.append(pos2)
else:
index2 = free2remaining[pos1]
if index2 is None:
raise ValueError("incompatible indices: %s and %s" % (free_ind1, free_ind2))
free2remaining[pos1] = None
free_ind2[pos1] = index1
if index1.is_up ^ index2.is_up:
if index1.is_up:
pos2up.append(pos1)
else:
pos2down.append(pos1)
if len(set(free_ind1) & set(free_ind2)) < len(free_ind1):
raise ValueError("incompatible indices: %s and %s" % (free_ind1, free_ind2))
# TODO: add possibility of metric after (spinors)
def contract_and_permute(metric, array, pos):
array = tensorcontraction(tensorproduct(metric, array), (1, 2+pos))
permu = list(range(len(free_ind1)))
permu[0], permu[pos] = permu[pos], permu[0]
return permutedims(array, permu)
# Raise indices:
for pos in pos2up:
metric = replacement_dict[index_types1[pos]]
metric_inverse = _TensorDataLazyEvaluator.inverse_matrix(metric)
array = contract_and_permute(metric_inverse, array, pos)
# Lower indices:
for pos in pos2down:
metric = replacement_dict[index_types1[pos]]
array = contract_and_permute(metric, array, pos)
if free_ind1:
permutation = TensExpr._get_indices_permutation(free_ind2, free_ind1)
array = permutedims(array, permutation)
if hasattr(array, "rank") and array.rank() == 0:
array = array[()]
return free_ind2, array
def replace_with_arrays(self, replacement_dict, indices):
"""
Replace the tensorial expressions with arrays. The final array will
correspond to the N-dimensional array with indices arranged according
to ``indices``.
Parameters
==========
replacement_dict
dictionary containing the replacement rules for tensors.
indices
the index order with respect to which the array is read.
Examples
========
>>> from sympy.tensor.tensor import TensorIndexType, tensor_indices
>>> from sympy.tensor.tensor import tensorhead
>>> from sympy import symbols, diag
>>> L = TensorIndexType("L")
>>> i, j = tensor_indices("i j", L)
>>> A = tensorhead("A", [L], [[1]])
>>> A(i).replace_with_arrays({A(i): [1, 2]}, [i])
[1, 2]
>>> expr = A(i)*A(j)
>>> expr.replace_with_arrays({A(i): [1, 2]}, [i, j])
[[1, 2], [2, 4]]
For contractions, specify the metric of the ``TensorIndexType``, which
in this case is ``L``, in its covariant form:
>>> expr = A(i)*A(-i)
>>> expr.replace_with_arrays({A(i): [1, 2], L: diag(1, -1)}, [])
-3
Symmetrization of an array:
>>> H = tensorhead("H", [L, L], [[1], [1]])
>>> a, b, c, d = symbols("a b c d")
>>> expr = H(i, j)/2 + H(j, i)/2
>>> expr.replace_with_arrays({H(i, j): [[a, b], [c, d]]}, [i, j])
[[a, b/2 + c/2], [b/2 + c/2, d]]
Anti-symmetrization of an array:
>>> expr = H(i, j)/2 - H(j, i)/2
>>> repl = {H(i, j): [[a, b], [c, d]]}
>>> expr.replace_with_arrays(repl, [i, j])
[[0, b/2 - c/2], [-b/2 + c/2, 0]]
The same expression can be read as the transpose by inverting ``i`` and
``j``:
>>> expr.replace_with_arrays(repl, [j, i])
[[0, -b/2 + c/2], [b/2 - c/2, 0]]
"""
from .array import Array
replacement_dict = {tensor: Array(array) for tensor, array in replacement_dict.items()}
# Check dimensions of replaced arrays:
for tensor, array in replacement_dict.items():
if isinstance(tensor, TensorIndexType):
expected_shape = [tensor.dim for i in range(2)]
else:
expected_shape = [index_type.dim for index_type in tensor.index_types]
if len(expected_shape) != array.rank() or (not all([dim1 == dim2 if
dim1 is not None else True for dim1, dim2 in zip(expected_shape,
array.shape)])):
raise ValueError("shapes for tensor %s expected to be %s, "\
"replacement array shape is %s" % (tensor, expected_shape,
array.shape))
ret_indices, array = self._extract_data(replacement_dict)
last_indices, array = self._match_indices_with_other_tensor(array, indices, ret_indices, replacement_dict)
#permutation = self._get_indices_permutation(indices, ret_indices)
#if not hasattr(array, "rank"):
#return array
#if array.rank() == 0:
#array = array[()]
#return array
#array = permutedims(array, permutation)
return array
def _check_add_Sum(self, expr, index_symbols):
from sympy import Sum
indices = self.get_indices()
dum = self.dum
sum_indices = [ (index_symbols[i], 0,
indices[i].tensor_index_type.dim-1) for i, j in dum]
if sum_indices:
expr = Sum(expr, *sum_indices)
return expr
class TensAdd(TensExpr, AssocOp):
"""
Sum of tensors
Parameters
==========
free_args : list of the free indices
Attributes
==========
``args`` : tuple of addends
``rank`` : rank of the tensor
``free_args`` : list of the free indices in sorted order
Notes
=====
Sum of more than one tensor are put automatically in canonical form.
Examples
========
>>> from sympy.tensor.tensor import TensorIndexType, tensorhead, tensor_indices
>>> Lorentz = TensorIndexType('Lorentz', dummy_fmt='L')
>>> a, b = tensor_indices('a,b', Lorentz)
>>> p, q = tensorhead('p,q', [Lorentz], [[1]])
>>> t = p(a) + q(a); t
p(a) + q(a)
>>> t(b)
p(b) + q(b)
Examples with components data added to the tensor expression:
>>> from sympy import symbols, diag
>>> x, y, z, t = symbols("x y z t")
>>> repl = {}
>>> repl[Lorentz] = diag(1, -1, -1, -1)
>>> repl[p(a)] = [1, 2, 3, 4]
>>> repl[q(a)] = [x, y, z, t]
The following are: 2**2 - 3**2 - 2**2 - 7**2 ==> -58
>>> expr = p(a) + q(a)
>>> expr.replace_with_arrays(repl, [a])
[x + 1, y + 2, z + 3, t + 4]
"""
def __new__(cls, *args, **kw_args):
args = [_sympify(x) for x in args if x]
args = TensAdd._tensAdd_flatten(args)
obj = Basic.__new__(cls, *args, **kw_args)
return obj
def doit(self, **kwargs):
deep = kwargs.get('deep', True)
if deep:
args = [arg.doit(**kwargs) for arg in self.args]
else:
args = self.args
if not args:
return S.Zero
if len(args) == 1 and not isinstance(args[0], TensExpr):
return args[0]
# now check that all addends have the same indices:
TensAdd._tensAdd_check(args)
# if TensAdd has only 1 element in its `args`:
if len(args) == 1: # and isinstance(args[0], TensMul):
return args[0]
# Remove zeros:
args = [x for x in args if x]
# if there are no more args (i.e. have cancelled out),
# just return zero:
if not args:
return S.Zero
if len(args) == 1:
return args[0]
# Collect terms appearing more than once, differing by their coefficients:
args = TensAdd._tensAdd_collect_terms(args)
# collect canonicalized terms
def sort_key(t):
x = get_index_structure(t)
if not isinstance(t, TensExpr):
return ([], [], [])
return (t.components, x.free, x.dum)
args.sort(key=sort_key)
if not args:
return S.Zero
# it there is only a component tensor return it
if len(args) == 1:
return args[0]
obj = self.func(*args)
return obj
@staticmethod
def _tensAdd_flatten(args):
# flatten TensAdd, coerce terms which are not tensors to tensors
a = []
for x in args:
if isinstance(x, (Add, TensAdd)):
a.extend(list(x.args))
else:
a.append(x)
args = [x for x in a if x.coeff]
return args
@staticmethod
def _tensAdd_check(args):
# check that all addends have the same free indices
indices0 = set([x[0] for x in get_index_structure(args[0]).free])
list_indices = [set([y[0] for y in get_index_structure(x).free]) for x in args[1:]]
if not all(x == indices0 for x in list_indices):
raise ValueError('all tensors must have the same indices')
@staticmethod
def _tensAdd_collect_terms(args):
# collect TensMul terms differing at most by their coefficient
terms_dict = defaultdict(list)
scalars = S.Zero
if isinstance(args[0], TensExpr):
free_indices = set(args[0].get_free_indices())
else:
free_indices = set([])
for arg in args:
if not isinstance(arg, TensExpr):
if free_indices != set([]):
raise ValueError("wrong valence")
scalars += arg
continue
if free_indices != set(arg.get_free_indices()):
raise ValueError("wrong valence")
# TODO: what is the part which is not a coeff?
# needs an implementation similar to .as_coeff_Mul()
terms_dict[arg.nocoeff].append(arg.coeff)
new_args = [TensMul(Add(*coeff), t).doit() for t, coeff in terms_dict.items() if Add(*coeff) != 0]
if isinstance(scalars, Add):
new_args = list(scalars.args) + new_args
elif scalars != 0:
new_args = [scalars] + new_args
return new_args
def get_indices(self):
indices = []
for arg in self.args:
indices.extend([i for i in get_indices(arg) if i not in indices])
return indices
@property
def rank(self):
return self.args[0].rank
@property
def free_args(self):
return self.args[0].free_args
def _expand(self, **hints):
return TensAdd(*[_expand(i, **hints) for i in self.args])
def __call__(self, *indices):
"""Returns tensor with ordered free indices replaced by ``indices``
Parameters
==========
indices
Examples
========
>>> from sympy import Symbol
>>> from sympy.tensor.tensor import TensorIndexType, tensor_indices, tensorhead
>>> D = Symbol('D')
>>> Lorentz = TensorIndexType('Lorentz', dim=D, dummy_fmt='L')
>>> i0,i1,i2,i3,i4 = tensor_indices('i0:5', Lorentz)
>>> p, q = tensorhead('p,q', [Lorentz], [[1]])
>>> g = Lorentz.metric
>>> t = p(i0)*p(i1) + g(i0,i1)*q(i2)*q(-i2)
>>> t(i0,i2)
metric(i0, i2)*q(L_0)*q(-L_0) + p(i0)*p(i2)
>>> from sympy.tensor.tensor import canon_bp
>>> canon_bp(t(i0,i1) - t(i1,i0))
0
"""
free_args = self.free_args
indices = list(indices)
if [x.tensor_index_type for x in indices] != [x.tensor_index_type for x in free_args]:
raise ValueError('incompatible types')
if indices == free_args:
return self
index_tuples = list(zip(free_args, indices))
a = [x.func(*x.fun_eval(*index_tuples).args) for x in self.args]
res = TensAdd(*a).doit()
return res
def canon_bp(self):
"""
canonicalize using the Butler-Portugal algorithm for canonicalization
under monoterm symmetries.
"""
expr = self.expand()
args = [canon_bp(x) for x in expr.args]
res = TensAdd(*args).doit()
return res
def equals(self, other):
other = _sympify(other)
if isinstance(other, TensMul) and other._coeff == 0:
return all(x._coeff == 0 for x in self.args)
if isinstance(other, TensExpr):
if self.rank != other.rank:
return False
if isinstance(other, TensAdd):
if set(self.args) != set(other.args):
return False
else:
return True
t = self - other
if not isinstance(t, TensExpr):
return t == 0
else:
if isinstance(t, TensMul):
return t._coeff == 0
else:
return all(x._coeff == 0 for x in t.args)
def __getitem__(self, item):
deprecate_data()
return self.data[item]
def contract_delta(self, delta):
args = [x.contract_delta(delta) for x in self.args]
t = TensAdd(*args).doit()
return canon_bp(t)
def contract_metric(self, g):
"""
Raise or lower indices with the metric ``g``
Parameters
==========
g : metric
contract_all : if True, eliminate all ``g`` which are contracted
Notes
=====
see the ``TensorIndexType`` docstring for the contraction conventions
"""
args = [contract_metric(x, g) for x in self.args]
t = TensAdd(*args).doit()
return canon_bp(t)
def fun_eval(self, *index_tuples):
"""
Return a tensor with free indices substituted according to ``index_tuples``
Parameters
==========
index_types : list of tuples ``(old_index, new_index)``
Examples
========
>>> from sympy.tensor.tensor import TensorIndexType, tensor_indices, tensorhead
>>> Lorentz = TensorIndexType('Lorentz', dummy_fmt='L')
>>> i, j, k, l = tensor_indices('i,j,k,l', Lorentz)
>>> A, B = tensorhead('A,B', [Lorentz]*2, [[1]*2])
>>> t = A(i, k)*B(-k, -j) + A(i, -j)
>>> t.fun_eval((i, k),(-j, l))
A(k, L_0)*B(-L_0, l) + A(k, l)
"""
args = self.args
args1 = []
for x in args:
y = x.fun_eval(*index_tuples)
args1.append(y)
return TensAdd(*args1).doit()
def substitute_indices(self, *index_tuples):
"""
Return a tensor with free indices substituted according to ``index_tuples``
Parameters
==========
index_types : list of tuples ``(old_index, new_index)``
Examples
========
>>> from sympy.tensor.tensor import TensorIndexType, tensor_indices, tensorhead
>>> Lorentz = TensorIndexType('Lorentz', dummy_fmt='L')
>>> i, j, k, l = tensor_indices('i,j,k,l', Lorentz)
>>> A, B = tensorhead('A,B', [Lorentz]*2, [[1]*2])
>>> t = A(i, k)*B(-k, -j); t
A(i, L_0)*B(-L_0, -j)
>>> t.substitute_indices((i,j), (j, k))
A(j, L_0)*B(-L_0, -k)
"""
args = self.args
args1 = []
for x in args:
y = x.substitute_indices(*index_tuples)
args1.append(y)
return TensAdd(*args1).doit()
def _print(self):
a = []
args = self.args
for x in args:
a.append(str(x))
a.sort()
s = ' + '.join(a)
s = s.replace('+ -', '- ')
return s
def _extract_data(self, replacement_dict):
from sympy.tensor.array import Array, permutedims
args_indices, arrays = zip(*[
arg._extract_data(replacement_dict) if
isinstance(arg, TensExpr) else ([], arg) for arg in self.args
])
arrays = [Array(i) for i in arrays]
ref_indices = args_indices[0]
for i in range(1, len(args_indices)):
indices = args_indices[i]
array = arrays[i]
permutation = TensMul._get_indices_permutation(indices, ref_indices)
arrays[i] = permutedims(array, permutation)
return ref_indices, sum(arrays, Array.zeros(*array.shape))
@property
def data(self):
deprecate_data()
return _tensor_data_substitution_dict[self.expand()]
@data.setter
def data(self, data):
deprecate_data()
_tensor_data_substitution_dict[self] = data
@data.deleter
def data(self):
deprecate_data()
if self in _tensor_data_substitution_dict:
del _tensor_data_substitution_dict[self]
def __iter__(self):
deprecate_data()
if not self.data:
raise ValueError("No iteration on abstract tensors")
return self.data.flatten().__iter__()
def _eval_rewrite_as_Indexed(self, *args):
return Add.fromiter(args)
class Tensor(TensExpr):
"""
Base tensor class, i.e. this represents a tensor, the single unit to be
put into an expression.
This object is usually created from a ``TensorHead``, by attaching indices
to it. Indices preceded by a minus sign are considered contravariant,
otherwise covariant.
Examples
========
>>> from sympy.tensor.tensor import TensorIndexType, tensor_indices, tensorhead
>>> Lorentz = TensorIndexType("Lorentz", dummy_fmt="L")
>>> mu, nu = tensor_indices('mu nu', Lorentz)
>>> A = tensorhead("A", [Lorentz, Lorentz], [[1], [1]])
>>> A(mu, -nu)
A(mu, -nu)
>>> A(mu, -mu)
A(L_0, -L_0)
"""
is_commutative = False
def __new__(cls, tensor_head, indices, **kw_args):
is_canon_bp = kw_args.pop('is_canon_bp', False)
indices = cls._parse_indices(tensor_head, indices)
obj = Basic.__new__(cls, tensor_head, Tuple(*indices), **kw_args)
obj._index_structure = _IndexStructure.from_indices(*indices)
obj._free_indices_set = set(obj._index_structure.get_free_indices())
if tensor_head.rank != len(indices):
raise ValueError("wrong number of indices")
obj._indices = indices
obj._is_canon_bp = is_canon_bp
obj._index_map = Tensor._build_index_map(indices, obj._index_structure)
return obj
@staticmethod
def _build_index_map(indices, index_structure):
index_map = {}
for idx in indices:
index_map[idx] = (indices.index(idx),)
return index_map
def doit(self, **kwargs):
args, indices, free, dum = TensMul._tensMul_contract_indices([self])
return args[0]
@staticmethod
def _parse_indices(tensor_head, indices):
if not isinstance(indices, (tuple, list, Tuple)):
raise TypeError("indices should be an array, got %s" % type(indices))
indices = list(indices)
for i, index in enumerate(indices):
if isinstance(index, Symbol):
indices[i] = TensorIndex(index, tensor_head.index_types[i], True)
elif isinstance(index, Mul):
c, e = index.as_coeff_Mul()
if c == -1 and isinstance(e, Symbol):
indices[i] = TensorIndex(e, tensor_head.index_types[i], False)
else:
raise ValueError("index not understood: %s" % index)
elif not isinstance(index, TensorIndex):
raise TypeError("wrong type for index: %s is %s" % (index, type(index)))
return indices
def _set_new_index_structure(self, im, is_canon_bp=False):
indices = im.get_indices()
return self._set_indices(*indices, is_canon_bp=is_canon_bp)
def _set_indices(self, *indices, **kw_args):
if len(indices) != self.ext_rank:
raise ValueError("indices length mismatch")
return self.func(self.args[0], indices, is_canon_bp=kw_args.pop('is_canon_bp', False)).doit()
def _get_free_indices_set(self):
return set([i[0] for i in self._index_structure.free])
def _get_dummy_indices_set(self):
dummy_pos = set(itertools.chain(*self._index_structure.dum))
return set(idx for i, idx in enumerate(self.args[1]) if i in dummy_pos)
def _get_indices_set(self):
return set(self.args[1].args)
@property
def is_canon_bp(self):
return self._is_canon_bp
@property
def indices(self):
return self._indices
@property
def free(self):
return self._index_structure.free[:]
@property
def free_in_args(self):
return [(ind, pos, 0) for ind, pos in self.free]
@property
def dum(self):
return self._index_structure.dum[:]
@property
def dum_in_args(self):
return [(p1, p2, 0, 0) for p1, p2 in self.dum]
@property
def rank(self):
return len(self.free)
@property
def ext_rank(self):
return self._index_structure._ext_rank
@property
def free_args(self):
return sorted([x[0] for x in self.free])
def commutes_with(self, other):
"""
:param other:
:return:
0 commute
1 anticommute
None neither commute nor anticommute
"""
if not isinstance(other, TensExpr):
return 0
elif isinstance(other, Tensor):
return self.component.commutes_with(other.component)
return NotImplementedError
def perm2tensor(self, g, is_canon_bp=False):
"""
Returns the tensor corresponding to the permutation ``g``
For further details, see the method in ``TIDS`` with the same name.
"""
return perm2tensor(self, g, is_canon_bp)
def canon_bp(self):
if self._is_canon_bp:
return self
expr = self.expand()
g, dummies, msym = expr._index_structure.indices_canon_args()
v = components_canon_args([expr.component])
can = canonicalize(g, dummies, msym, *v)
if can == 0:
return S.Zero
tensor = self.perm2tensor(can, True)
return tensor
@property
def index_types(self):
return list(self.component.index_types)
@property
def coeff(self):
return S.One
@property
def nocoeff(self):
return self
@property
def component(self):
return self.args[0]
@property
def components(self):
return [self.args[0]]
def split(self):
return [self]
def _expand(self, **kwargs):
return self
def sorted_components(self):
return self
def get_indices(self):
"""
Get a list of indices, corresponding to those of the tensor.
"""
return list(self.args[1])
def get_free_indices(self):
"""
Get a list of free indices, corresponding to those of the tensor.
"""
return self._index_structure.get_free_indices()
def as_base_exp(self):
return self, S.One
def substitute_indices(self, *index_tuples):
return substitute_indices(self, *index_tuples)
def __call__(self, *indices):
"""Returns tensor with ordered free indices replaced by ``indices``
Examples
========
>>> from sympy.tensor.tensor import TensorIndexType, tensor_indices, tensorhead
>>> Lorentz = TensorIndexType('Lorentz', dummy_fmt='L')
>>> i0,i1,i2,i3,i4 = tensor_indices('i0:5', Lorentz)
>>> A = tensorhead('A', [Lorentz]*5, [[1]*5])
>>> t = A(i2, i1, -i2, -i3, i4)
>>> t
A(L_0, i1, -L_0, -i3, i4)
>>> t(i1, i2, i3)
A(L_0, i1, -L_0, i2, i3)
"""
free_args = self.free_args
indices = list(indices)
if [x.tensor_index_type for x in indices] != [x.tensor_index_type for x in free_args]:
raise ValueError('incompatible types')
if indices == free_args:
return self
t = self.fun_eval(*list(zip(free_args, indices)))
# object is rebuilt in order to make sure that all contracted indices
# get recognized as dummies, but only if there are contracted indices.
if len(set(i if i.is_up else -i for i in indices)) != len(indices):
return t.func(*t.args)
return t
# TODO: put this into TensExpr?
def __iter__(self):
deprecate_data()
return self.data.__iter__()
# TODO: put this into TensExpr?
def __getitem__(self, item):
deprecate_data()
return self.data[item]
def _extract_data(self, replacement_dict):
from .array import Array
for k, v in replacement_dict.items():
if isinstance(k, Tensor) and k.args[0] == self.args[0]:
other = k
array = v
break
else:
raise ValueError("%s not found in %s" % (self, replacement_dict))
# TODO: inefficient, this should be done at root level only:
replacement_dict = {k: Array(v) for k, v in replacement_dict.items()}
array = Array(array)
dum1 = self.dum
dum2 = other.dum
if len(dum2) > 0:
for pair in dum2:
# allow `dum2` if the contained values are also in `dum1`.
if pair not in dum1:
raise NotImplementedError("%s with contractions is not implemented" % other)
# Remove elements in `dum2` from `dum1`:
dum1 = [pair for pair in dum1 if pair not in dum2]
if len(dum1) > 0:
indices2 = other.get_indices()
repl = {}
for p1, p2 in dum1:
repl[indices2[p2]] = -indices2[p1]
other = other.xreplace(repl).doit()
array = _TensorDataLazyEvaluator.data_contract_dum([array], dum1, len(indices2))
free_ind1 = self.get_free_indices()
free_ind2 = other.get_free_indices()
return self._match_indices_with_other_tensor(array, free_ind1, free_ind2, replacement_dict)
@property
def data(self):
deprecate_data()
return _tensor_data_substitution_dict[self]
@data.setter
def data(self, data):
deprecate_data()
# TODO: check data compatibility with properties of tensor.
_tensor_data_substitution_dict[self] = data
@data.deleter
def data(self):
deprecate_data()
if self in _tensor_data_substitution_dict:
del _tensor_data_substitution_dict[self]
if self.metric in _tensor_data_substitution_dict:
del _tensor_data_substitution_dict[self.metric]
def _print(self):
indices = [str(ind) for ind in self.indices]
component = self.component
if component.rank > 0:
return ('%s(%s)' % (component.name, ', '.join(indices)))
else:
return ('%s' % component.name)
def equals(self, other):
if other == 0:
return self.coeff == 0
other = _sympify(other)
if not isinstance(other, TensExpr):
assert not self.components
return S.One == other
def _get_compar_comp(self):
t = self.canon_bp()
r = (t.coeff, tuple(t.components), \
tuple(sorted(t.free)), tuple(sorted(t.dum)))
return r
return _get_compar_comp(self) == _get_compar_comp(other)
def contract_metric(self, g):
# if metric is not the same, ignore this step:
if self.component != g:
return self
# in case there are free components, do not perform anything:
if len(self.free) != 0:
return self
antisym = g.index_types[0].metric_antisym
sign = S.One
typ = g.index_types[0]
if not antisym:
# g(i, -i)
if typ._dim is None:
raise ValueError('dimension not assigned')
sign = sign*typ._dim
else:
# g(i, -i)
if typ._dim is None:
raise ValueError('dimension not assigned')
sign = sign*typ._dim
dp0, dp1 = self.dum[0]
if dp0 < dp1:
# g(i, -i) = -D with antisymmetric metric
sign = -sign
return sign
def contract_delta(self, metric):
return self.contract_metric(metric)
def _eval_rewrite_as_Indexed(self, tens, indices):
from sympy import Indexed
# TODO: replace .args[0] with .name:
index_symbols = [i.args[0] for i in self.get_indices()]
expr = Indexed(tens.args[0], *index_symbols)
return self._check_add_Sum(expr, index_symbols)
class TensMul(TensExpr, AssocOp):
"""
Product of tensors
Parameters
==========
coeff : SymPy coefficient of the tensor
args
Attributes
==========
``components`` : list of ``TensorHead`` of the component tensors
``types`` : list of nonrepeated ``TensorIndexType``
``free`` : list of ``(ind, ipos, icomp)``, see Notes
``dum`` : list of ``(ipos1, ipos2, icomp1, icomp2)``, see Notes
``ext_rank`` : rank of the tensor counting the dummy indices
``rank`` : rank of the tensor
``coeff`` : SymPy coefficient of the tensor
``free_args`` : list of the free indices in sorted order
``is_canon_bp`` : ``True`` if the tensor in in canonical form
Notes
=====
``args[0]`` list of ``TensorHead`` of the component tensors.
``args[1]`` list of ``(ind, ipos, icomp)``
where ``ind`` is a free index, ``ipos`` is the slot position
of ``ind`` in the ``icomp``-th component tensor.
``args[2]`` list of tuples representing dummy indices.
``(ipos1, ipos2, icomp1, icomp2)`` indicates that the contravariant
dummy index is the ``ipos1``-th slot position in the ``icomp1``-th
component tensor; the corresponding covariant index is
in the ``ipos2`` slot position in the ``icomp2``-th component tensor.
"""
identity = S.One
def __new__(cls, *args, **kw_args):
is_canon_bp = kw_args.get('is_canon_bp', False)
args = list(map(_sympify, args))
# Flatten:
args = [i for arg in args for i in (arg.args if isinstance(arg, (TensMul, Mul)) else [arg])]
args, indices, free, dum = TensMul._tensMul_contract_indices(args, replace_indices=False)
# Data for indices:
index_types = [i.tensor_index_type for i in indices]
index_structure = _IndexStructure(free, dum, index_types, indices, canon_bp=is_canon_bp)
obj = TensExpr.__new__(cls, *args)
obj._indices = indices
obj._index_types = index_types
obj._index_structure = index_structure
obj._ext_rank = len(obj._index_structure.free) + 2*len(obj._index_structure.dum)
obj._coeff = S.One
obj._is_canon_bp = is_canon_bp
return obj
@staticmethod
def _indices_to_free_dum(args_indices):
free2pos1 = {}
free2pos2 = {}
dummy_data = []
indices = []
# Notation for positions (to better understand the code):
# `pos1`: position in the `args`.
# `pos2`: position in the indices.
# Example:
# A(i, j)*B(k, m, n)*C(p)
# `pos1` of `n` is 1 because it's in `B` (second `args` of TensMul).
# `pos2` of `n` is 4 because it's the fifth overall index.
# Counter for the index position wrt the whole expression:
pos2 = 0
for pos1, arg_indices in enumerate(args_indices):
for index_pos, index in enumerate(arg_indices):
if not isinstance(index, TensorIndex):
raise TypeError("expected TensorIndex")
if -index in free2pos1:
# Dummy index detected:
other_pos1 = free2pos1.pop(-index)
other_pos2 = free2pos2.pop(-index)
if index.is_up:
dummy_data.append((index, pos1, other_pos1, pos2, other_pos2))
else:
dummy_data.append((-index, other_pos1, pos1, other_pos2, pos2))
indices.append(index)
elif index in free2pos1:
raise ValueError("Repeated index: %s" % index)
else:
free2pos1[index] = pos1
free2pos2[index] = pos2
indices.append(index)
pos2 += 1
free = [(i, p) for (i, p) in free2pos2.items()]
free_names = [i.name for i in free2pos2.keys()]
dummy_data.sort(key=lambda x: x[3])
return indices, free, free_names, dummy_data
@staticmethod
def _dummy_data_to_dum(dummy_data):
return [(p2a, p2b) for (i, p1a, p1b, p2a, p2b) in dummy_data]
@staticmethod
def _tensMul_contract_indices(args, replace_indices=True):
replacements = [{} for arg in args]
#_index_order = all([_has_index_order(arg) for arg in args])
args_indices = [get_indices(arg) for arg in args]
indices, free, free_names, dummy_data = TensMul._indices_to_free_dum(args_indices)
cdt = defaultdict(int)
def dummy_fmt_gen(tensor_index_type):
fmt = tensor_index_type.dummy_fmt
nd = cdt[tensor_index_type]
cdt[tensor_index_type] += 1
return fmt % nd
if replace_indices:
for old_index, pos1cov, pos1contra, pos2cov, pos2contra in dummy_data:
index_type = old_index.tensor_index_type
while True:
dummy_name = dummy_fmt_gen(index_type)
if dummy_name not in free_names:
break
dummy = TensorIndex(dummy_name, index_type, True)
replacements[pos1cov][old_index] = dummy
replacements[pos1contra][-old_index] = -dummy
indices[pos2cov] = dummy
indices[pos2contra] = -dummy
args = [arg.xreplace(repl) for arg, repl in zip(args, replacements)]
dum = TensMul._dummy_data_to_dum(dummy_data)
return args, indices, free, dum
@staticmethod
def _get_components_from_args(args):
"""
Get a list of ``Tensor`` objects having the same ``TIDS`` if multiplied
by one another.
"""
components = []
for arg in args:
if not isinstance(arg, TensExpr):
continue
if isinstance(arg, TensAdd):
continue
components.extend(arg.components)
return components
@staticmethod
def _rebuild_tensors_list(args, index_structure):
indices = index_structure.get_indices()
#tensors = [None for i in components] # pre-allocate list
ind_pos = 0
for i, arg in enumerate(args):
if not isinstance(arg, TensExpr):
continue
prev_pos = ind_pos
ind_pos += arg.ext_rank
args[i] = Tensor(arg.component, indices[prev_pos:ind_pos])
def doit(self, **kwargs):
is_canon_bp = self._is_canon_bp
deep = kwargs.get('deep', True)
if deep:
args = [arg.doit(**kwargs) for arg in self.args]
else:
args = self.args
args = [arg for arg in args if arg != self.identity]
# Extract non-tensor coefficients:
coeff = reduce(lambda a, b: a*b, [arg for arg in args if not isinstance(arg, TensExpr)], S.One)
args = [arg for arg in args if isinstance(arg, TensExpr)]
if len(args) == 0:
return coeff
if coeff != self.identity:
args = [coeff] + args
if coeff == 0:
return S.Zero
if len(args) == 1:
return args[0]
args, indices, free, dum = TensMul._tensMul_contract_indices(args)
# Data for indices:
index_types = [i.tensor_index_type for i in indices]
index_structure = _IndexStructure(free, dum, index_types, indices, canon_bp=is_canon_bp)
obj = self.func(*args)
obj._index_types = index_types
obj._index_structure = index_structure
obj._ext_rank = len(obj._index_structure.free) + 2*len(obj._index_structure.dum)
obj._coeff = coeff
obj._is_canon_bp = is_canon_bp
return obj
# TODO: this method should be private
# TODO: should this method be renamed _from_components_free_dum ?
@staticmethod
def from_data(coeff, components, free, dum, **kw_args):
return TensMul(coeff, *TensMul._get_tensors_from_components_free_dum(components, free, dum), **kw_args).doit()
@staticmethod
def _get_tensors_from_components_free_dum(components, free, dum):
"""
Get a list of ``Tensor`` objects by distributing ``free`` and ``dum`` indices on the ``components``.
"""
index_structure = _IndexStructure.from_components_free_dum(components, free, dum)
indices = index_structure.get_indices()
tensors = [None for i in components] # pre-allocate list
# distribute indices on components to build a list of tensors:
ind_pos = 0
for i, component in enumerate(components):
prev_pos = ind_pos
ind_pos += component.rank
tensors[i] = Tensor(component, indices[prev_pos:ind_pos])
return tensors
def _get_free_indices_set(self):
return set([i[0] for i in self.free])
def _get_dummy_indices_set(self):
dummy_pos = set(itertools.chain(*self.dum))
return set(idx for i, idx in enumerate(self._index_structure.get_indices()) if i in dummy_pos)
def _get_position_offset_for_indices(self):
arg_offset = [None for i in range(self.ext_rank)]
counter = 0
for i, arg in enumerate(self.args):
if not isinstance(arg, TensExpr):
continue
for j in range(arg.ext_rank):
arg_offset[j + counter] = counter
counter += arg.ext_rank
return arg_offset
@property
def free_args(self):
return sorted([x[0] for x in self.free])
@property
def components(self):
return self._get_components_from_args(self.args)
@property
def free(self):
return self._index_structure.free[:]
@property
def free_in_args(self):
arg_offset = self._get_position_offset_for_indices()
argpos = self._get_indices_to_args_pos()
return [(ind, pos-arg_offset[pos], argpos[pos]) for (ind, pos) in self.free]
@property
def coeff(self):
return self._coeff
@property
def nocoeff(self):
return self.func(*[t for t in self.args if isinstance(t, TensExpr)]).doit()
@property
def dum(self):
return self._index_structure.dum[:]
@property
def dum_in_args(self):
arg_offset = self._get_position_offset_for_indices()
argpos = self._get_indices_to_args_pos()
return [(p1-arg_offset[p1], p2-arg_offset[p2], argpos[p1], argpos[p2]) for p1, p2 in self.dum]
@property
def rank(self):
return len(self.free)
@property
def ext_rank(self):
return self._ext_rank
@property
def index_types(self):
return self._index_types[:]
def equals(self, other):
if other == 0:
return self.coeff == 0
other = _sympify(other)
if not isinstance(other, TensExpr):
assert not self.components
return self._coeff == other
return self.canon_bp() == other.canon_bp()
def get_indices(self):
"""
Returns the list of indices of the tensor
The indices are listed in the order in which they appear in the
component tensors.
The dummy indices are given a name which does not collide with
the names of the free indices.
Examples
========
>>> from sympy.tensor.tensor import TensorIndexType, tensor_indices, tensorhead
>>> Lorentz = TensorIndexType('Lorentz', dummy_fmt='L')
>>> m0, m1, m2 = tensor_indices('m0,m1,m2', Lorentz)
>>> g = Lorentz.metric
>>> p, q = tensorhead('p,q', [Lorentz], [[1]])
>>> t = p(m1)*g(m0,m2)
>>> t.get_indices()
[m1, m0, m2]
>>> t2 = p(m1)*g(-m1, m2)
>>> t2.get_indices()
[L_0, -L_0, m2]
"""
return self._indices
def get_free_indices(self):
"""
Returns the list of free indices of the tensor
The indices are listed in the order in which they appear in the
component tensors.
Examples
========
>>> from sympy.tensor.tensor import TensorIndexType, tensor_indices, tensorhead
>>> Lorentz = TensorIndexType('Lorentz', dummy_fmt='L')
>>> m0, m1, m2 = tensor_indices('m0,m1,m2', Lorentz)
>>> g = Lorentz.metric
>>> p, q = tensorhead('p,q', [Lorentz], [[1]])
>>> t = p(m1)*g(m0,m2)
>>> t.get_free_indices()
[m1, m0, m2]
>>> t2 = p(m1)*g(-m1, m2)
>>> t2.get_free_indices()
[m2]
"""
return self._index_structure.get_free_indices()
def split(self):
"""
Returns a list of tensors, whose product is ``self``
Dummy indices contracted among different tensor components
become free indices with the same name as the one used to
represent the dummy indices.
Examples
========
>>> from sympy.tensor.tensor import TensorIndexType, tensor_indices, tensorhead
>>> Lorentz = TensorIndexType('Lorentz', dummy_fmt='L')
>>> a, b, c, d = tensor_indices('a,b,c,d', Lorentz)
>>> A, B = tensorhead('A,B', [Lorentz]*2, [[1]*2])
>>> t = A(a,b)*B(-b,c)
>>> t
A(a, L_0)*B(-L_0, c)
>>> t.split()
[A(a, L_0), B(-L_0, c)]
"""
if self.args == ():
return [self]
splitp = []
res = 1
for arg in self.args:
if isinstance(arg, Tensor):
splitp.append(res*arg)
res = 1
else:
res *= arg
return splitp
def _expand(self, **hints):
# TODO: temporary solution, in the future this should be linked to
# `Expr.expand`.
args = [_expand(arg, **hints) for arg in self.args]
args1 = [arg.args if isinstance(arg, (Add, TensAdd)) else (arg,) for arg in args]
return TensAdd(*[
TensMul(*i) for i in itertools.product(*args1)]
)
def __neg__(self):
return TensMul(S.NegativeOne, self, is_canon_bp=self._is_canon_bp).doit()
def __getitem__(self, item):
deprecate_data()
return self.data[item]
def _get_args_for_traditional_printer(self):
args = list(self.args)
if (self.coeff < 0) == True:
# expressions like "-A(a)"
sign = "-"
if self.coeff == S.NegativeOne:
args = args[1:]
else:
args[0] = -args[0]
else:
sign = ""
return sign, args
def _sort_args_for_sorted_components(self):
"""
Returns the ``args`` sorted according to the components commutation
properties.
The sorting is done taking into account the commutation group
of the component tensors.
"""
cv = [arg for arg in self.args if isinstance(arg, TensExpr)]
sign = 1
n = len(cv) - 1
for i in range(n):
for j in range(n, i, -1):
c = cv[j-1].commutes_with(cv[j])
# if `c` is `None`, it does neither commute nor anticommute, skip:
if c not in [0, 1]:
continue
if (cv[j-1].component.types, cv[j-1].component.name) > \
(cv[j].component.types, cv[j].component.name):
cv[j-1], cv[j] = cv[j], cv[j-1]
# if `c` is 1, the anticommute, so change sign:
if c:
sign = -sign
coeff = sign * self.coeff
if coeff != 1:
return [coeff] + cv
return cv
def sorted_components(self):
"""
Returns a tensor product with sorted components.
"""
return TensMul(*self._sort_args_for_sorted_components()).doit()
def perm2tensor(self, g, is_canon_bp=False):
"""
Returns the tensor corresponding to the permutation ``g``
For further details, see the method in ``TIDS`` with the same name.
"""
return perm2tensor(self, g, is_canon_bp=is_canon_bp)
def canon_bp(self):
"""
Canonicalize using the Butler-Portugal algorithm for canonicalization
under monoterm symmetries.
Examples
========
>>> from sympy.tensor.tensor import TensorIndexType, tensor_indices, tensorhead
>>> Lorentz = TensorIndexType('Lorentz', dummy_fmt='L')
>>> m0, m1, m2 = tensor_indices('m0,m1,m2', Lorentz)
>>> A = tensorhead('A', [Lorentz]*2, [[2]])
>>> t = A(m0,-m1)*A(m1,-m0)
>>> t.canon_bp()
-A(L_0, L_1)*A(-L_0, -L_1)
>>> t = A(m0,-m1)*A(m1,-m2)*A(m2,-m0)
>>> t.canon_bp()
0
"""
if self._is_canon_bp:
return self
expr = self.expand()
if isinstance(expr, TensAdd):
return expr.canon_bp()
if not expr.components:
return expr
t = expr.sorted_components()
g, dummies, msym = t._index_structure.indices_canon_args()
v = components_canon_args(t.components)
can = canonicalize(g, dummies, msym, *v)
if can == 0:
return S.Zero
tmul = t.perm2tensor(can, True)
return tmul
def contract_delta(self, delta):
t = self.contract_metric(delta)
return t
def _get_indices_to_args_pos(self):
"""
Get a dict mapping the index position to TensMul's argument number.
"""
pos_map = dict()
pos_counter = 0
for arg_i, arg in enumerate(self.args):
if not isinstance(arg, TensExpr):
continue
assert isinstance(arg, Tensor)
for i in range(arg.ext_rank):
pos_map[pos_counter] = arg_i
pos_counter += 1
return pos_map
def contract_metric(self, g):
"""
Raise or lower indices with the metric ``g``
Parameters
==========
g : metric
Notes
=====
see the ``TensorIndexType`` docstring for the contraction conventions
Examples
========
>>> from sympy.tensor.tensor import TensorIndexType, tensor_indices, tensorhead
>>> Lorentz = TensorIndexType('Lorentz', dummy_fmt='L')
>>> m0, m1, m2 = tensor_indices('m0,m1,m2', Lorentz)
>>> g = Lorentz.metric
>>> p, q = tensorhead('p,q', [Lorentz], [[1]])
>>> t = p(m0)*q(m1)*g(-m0, -m1)
>>> t.canon_bp()
metric(L_0, L_1)*p(-L_0)*q(-L_1)
>>> t.contract_metric(g).canon_bp()
p(L_0)*q(-L_0)
"""
expr = self.expand()
if self != expr:
expr = expr.canon_bp()
return expr.contract_metric(g)
pos_map = self._get_indices_to_args_pos()
args = list(self.args)
antisym = g.index_types[0].metric_antisym
# list of positions of the metric ``g`` inside ``args``
gpos = [i for i, x in enumerate(self.args) if isinstance(x, Tensor) and x.component == g]
if not gpos:
return self
# Sign is either 1 or -1, to correct the sign after metric contraction
# (for spinor indices).
sign = 1
dum = self.dum[:]
free = self.free[:]
elim = set()
for gposx in gpos:
if gposx in elim:
continue
free1 = [x for x in free if pos_map[x[1]] == gposx]
dum1 = [x for x in dum if pos_map[x[0]] == gposx or pos_map[x[1]] == gposx]
if not dum1:
continue
elim.add(gposx)
# subs with the multiplication neutral element, that is, remove it:
args[gposx] = 1
if len(dum1) == 2:
if not antisym:
dum10, dum11 = dum1
if pos_map[dum10[1]] == gposx:
# the index with pos p0 contravariant
p0 = dum10[0]
else:
# the index with pos p0 is covariant
p0 = dum10[1]
if pos_map[dum11[1]] == gposx:
# the index with pos p1 is contravariant
p1 = dum11[0]
else:
# the index with pos p1 is covariant
p1 = dum11[1]
dum.append((p0, p1))
else:
dum10, dum11 = dum1
# change the sign to bring the indices of the metric to contravariant
# form; change the sign if dum10 has the metric index in position 0
if pos_map[dum10[1]] == gposx:
# the index with pos p0 is contravariant
p0 = dum10[0]
if dum10[1] == 1:
sign = -sign
else:
# the index with pos p0 is covariant
p0 = dum10[1]
if dum10[0] == 0:
sign = -sign
if pos_map[dum11[1]] == gposx:
# the index with pos p1 is contravariant
p1 = dum11[0]
sign = -sign
else:
# the index with pos p1 is covariant
p1 = dum11[1]
dum.append((p0, p1))
elif len(dum1) == 1:
if not antisym:
dp0, dp1 = dum1[0]
if pos_map[dp0] == pos_map[dp1]:
# g(i, -i)
typ = g.index_types[0]
if typ._dim is None:
raise ValueError('dimension not assigned')
sign = sign*typ._dim
else:
# g(i0, i1)*p(-i1)
if pos_map[dp0] == gposx:
p1 = dp1
else:
p1 = dp0
ind, p = free1[0]
free.append((ind, p1))
else:
dp0, dp1 = dum1[0]
if pos_map[dp0] == pos_map[dp1]:
# g(i, -i)
typ = g.index_types[0]
if typ._dim is None:
raise ValueError('dimension not assigned')
sign = sign*typ._dim
if dp0 < dp1:
# g(i, -i) = -D with antisymmetric metric
sign = -sign
else:
# g(i0, i1)*p(-i1)
if pos_map[dp0] == gposx:
p1 = dp1
if dp0 == 0:
sign = -sign
else:
p1 = dp0
ind, p = free1[0]
free.append((ind, p1))
dum = [x for x in dum if x not in dum1]
free = [x for x in free if x not in free1]
# shift positions:
shift = 0
shifts = [0]*len(args)
for i in range(len(args)):
if i in elim:
shift += 2
continue
shifts[i] = shift
free = [(ind, p - shifts[pos_map[p]]) for (ind, p) in free if pos_map[p] not in elim]
dum = [(p0 - shifts[pos_map[p0]], p1 - shifts[pos_map[p1]]) for i, (p0, p1) in enumerate(dum) if pos_map[p0] not in elim and pos_map[p1] not in elim]
res = sign*TensMul(*args).doit()
if not isinstance(res, TensExpr):
return res
im = _IndexStructure.from_components_free_dum(res.components, free, dum)
return res._set_new_index_structure(im)
def _set_new_index_structure(self, im, is_canon_bp=False):
indices = im.get_indices()
return self._set_indices(*indices, is_canon_bp=is_canon_bp)
def _set_indices(self, *indices, **kw_args):
if len(indices) != self.ext_rank:
raise ValueError("indices length mismatch")
args = list(self.args)[:]
pos = 0
is_canon_bp = kw_args.pop('is_canon_bp', False)
for i, arg in enumerate(args):
if not isinstance(arg, TensExpr):
continue
assert isinstance(arg, Tensor)
ext_rank = arg.ext_rank
args[i] = arg._set_indices(*indices[pos:pos+ext_rank])
pos += ext_rank
return TensMul(*args, is_canon_bp=is_canon_bp).doit()
@staticmethod
def _index_replacement_for_contract_metric(args, free, dum):
for arg in args:
if not isinstance(arg, TensExpr):
continue
assert isinstance(arg, Tensor)
def substitute_indices(self, *index_tuples):
return substitute_indices(self, *index_tuples)
def __call__(self, *indices):
"""Returns tensor product with ordered free indices replaced by ``indices``
Examples
========
>>> from sympy import Symbol
>>> from sympy.tensor.tensor import TensorIndexType, tensor_indices, tensorhead
>>> D = Symbol('D')
>>> Lorentz = TensorIndexType('Lorentz', dim=D, dummy_fmt='L')
>>> i0,i1,i2,i3,i4 = tensor_indices('i0:5', Lorentz)
>>> g = Lorentz.metric
>>> p, q = tensorhead('p,q', [Lorentz], [[1]])
>>> t = p(i0)*q(i1)*q(-i1)
>>> t(i1)
p(i1)*q(L_0)*q(-L_0)
"""
free_args = self.free_args
indices = list(indices)
if [x.tensor_index_type for x in indices] != [x.tensor_index_type for x in free_args]:
raise ValueError('incompatible types')
if indices == free_args:
return self
t = self.fun_eval(*list(zip(free_args, indices)))
# object is rebuilt in order to make sure that all contracted indices
# get recognized as dummies, but only if there are contracted indices.
if len(set(i if i.is_up else -i for i in indices)) != len(indices):
return t.func(*t.args)
return t
def _extract_data(self, replacement_dict):
args_indices, arrays = zip(*[arg._extract_data(replacement_dict) for arg in self.args if isinstance(arg, TensExpr)])
coeff = reduce(operator.mul, [a for a in self.args if not isinstance(a, TensExpr)], S.One)
indices, free, free_names, dummy_data = TensMul._indices_to_free_dum(args_indices)
dum = TensMul._dummy_data_to_dum(dummy_data)
ext_rank = self.ext_rank
free.sort(key=lambda x: x[1])
free_indices = [i[0] for i in free]
return free_indices, coeff*_TensorDataLazyEvaluator.data_contract_dum(arrays, dum, ext_rank)
@property
def data(self):
deprecate_data()
dat = _tensor_data_substitution_dict[self.expand()]
return dat
@data.setter
def data(self, data):
deprecate_data()
raise ValueError("Not possible to set component data to a tensor expression")
@data.deleter
def data(self):
deprecate_data()
raise ValueError("Not possible to delete component data to a tensor expression")
def __iter__(self):
deprecate_data()
if self.data is None:
raise ValueError("No iteration on abstract tensors")
return self.data.__iter__()
def _eval_rewrite_as_Indexed(self, *args):
from sympy import Sum
index_symbols = [i.args[0] for i in self.get_indices()]
args = [arg.args[0] if isinstance(arg, Sum) else arg for arg in args]
expr = Mul.fromiter(args)
return self._check_add_Sum(expr, index_symbols)
class TensorElement(TensExpr):
"""
Tensor with evaluated components.
Examples
========
>>> from sympy.tensor.tensor import TensorIndexType, tensorhead
>>> from sympy import symbols
>>> L = TensorIndexType("L")
>>> i, j, k = symbols("i j k")
>>> A = tensorhead("A", [L, L], [[1], [1]])
>>> A(i, j).get_free_indices()
[i, j]
If we want to set component ``i`` to a specific value, use the
``TensorElement`` class:
>>> from sympy.tensor.tensor import TensorElement
>>> te = TensorElement(A(i, j), {i: 2})
As index ``i`` has been accessed (``{i: 2}`` is the evaluation of its 3rd
element), the free indices will only contain ``j``:
>>> te.get_free_indices()
[j]
"""
def __new__(cls, expr, index_map):
if not isinstance(expr, Tensor):
# remap
if not isinstance(expr, TensExpr):
raise TypeError("%s is not a tensor expression" % expr)
return expr.func(*[TensorElement(arg, index_map) for arg in expr.args])
expr_free_indices = expr.get_free_indices()
name_translation = {i.args[0]: i for i in expr_free_indices}
index_map = {name_translation.get(index, index): value for index, value in index_map.items()}
index_map = {index: value for index, value in index_map.items() if index in expr_free_indices}
if len(index_map) == 0:
return expr
free_indices = [i for i in expr_free_indices if i not in index_map.keys()]
index_map = Dict(index_map)
obj = TensExpr.__new__(cls, expr, index_map)
obj._free_indices = free_indices
return obj
@property
def free(self):
return [(index, i) for i, index in enumerate(self.get_free_indices())]
@property
def dum(self):
# TODO: inherit dummies from expr
return []
@property
def expr(self):
return self._args[0]
@property
def index_map(self):
return self._args[1]
def get_free_indices(self):
return self._free_indices
def get_indices(self):
return self.get_free_indices()
def _extract_data(self, replacement_dict):
ret_indices, array = self.expr._extract_data(replacement_dict)
index_map = self.index_map
slice_tuple = tuple(index_map.get(i, slice(None)) for i in ret_indices)
ret_indices = [i for i in ret_indices if i not in index_map]
array = array.__getitem__(slice_tuple)
return ret_indices, array
def canon_bp(p):
"""
Butler-Portugal canonicalization
"""
if isinstance(p, TensExpr):
return p.canon_bp()
return p
def tensor_mul(*a):
"""
product of tensors
"""
if not a:
return TensMul.from_data(S.One, [], [], [])
t = a[0]
for tx in a[1:]:
t = t*tx
return t
def riemann_cyclic_replace(t_r):
"""
replace Riemann tensor with an equivalent expression
``R(m,n,p,q) -> 2/3*R(m,n,p,q) - 1/3*R(m,q,n,p) + 1/3*R(m,p,n,q)``
"""
free = sorted(t_r.free, key=lambda x: x[1])
m, n, p, q = [x[0] for x in free]
t0 = S(2)/3*t_r
t1 = - S(1)/3*t_r.substitute_indices((m,m),(n,q),(p,n),(q,p))
t2 = S(1)/3*t_r.substitute_indices((m,m),(n,p),(p,n),(q,q))
t3 = t0 + t1 + t2
return t3
def riemann_cyclic(t2):
"""
replace each Riemann tensor with an equivalent expression
satisfying the cyclic identity.
This trick is discussed in the reference guide to Cadabra.
Examples
========
>>> from sympy.tensor.tensor import TensorIndexType, tensor_indices, tensorhead, riemann_cyclic
>>> Lorentz = TensorIndexType('Lorentz', dummy_fmt='L')
>>> i, j, k, l = tensor_indices('i,j,k,l', Lorentz)
>>> R = tensorhead('R', [Lorentz]*4, [[2, 2]])
>>> t = R(i,j,k,l)*(R(-i,-j,-k,-l) - 2*R(-i,-k,-j,-l))
>>> riemann_cyclic(t)
0
"""
t2 = t2.expand()
if isinstance(t2, (TensMul, Tensor)):
args = [t2]
else:
args = t2.args
a1 = [x.split() for x in args]
a2 = [[riemann_cyclic_replace(tx) for tx in y] for y in a1]
a3 = [tensor_mul(*v) for v in a2]
t3 = TensAdd(*a3).doit()
if not t3:
return t3
else:
return canon_bp(t3)
def get_lines(ex, index_type):
"""
returns ``(lines, traces, rest)`` for an index type,
where ``lines`` is the list of list of positions of a matrix line,
``traces`` is the list of list of traced matrix lines,
``rest`` is the rest of the elements ot the tensor.
"""
def _join_lines(a):
i = 0
while i < len(a):
x = a[i]
xend = x[-1]
xstart = x[0]
hit = True
while hit:
hit = False
for j in range(i + 1, len(a)):
if j >= len(a):
break
if a[j][0] == xend:
hit = True
x.extend(a[j][1:])
xend = x[-1]
a.pop(j)
continue
if a[j][0] == xstart:
hit = True
a[i] = reversed(a[j][1:]) + x
x = a[i]
xstart = a[i][0]
a.pop(j)
continue
if a[j][-1] == xend:
hit = True
x.extend(reversed(a[j][:-1]))
xend = x[-1]
a.pop(j)
continue
if a[j][-1] == xstart:
hit = True
a[i] = a[j][:-1] + x
x = a[i]
xstart = x[0]
a.pop(j)
continue
i += 1
return a
arguments = ex.args
dt = {}
for c in ex.args:
if not isinstance(c, TensExpr):
continue
if c in dt:
continue
index_types = c.index_types
a = []
for i in range(len(index_types)):
if index_types[i] is index_type:
a.append(i)
if len(a) > 2:
raise ValueError('at most two indices of type %s allowed' % index_type)
if len(a) == 2:
dt[c] = a
#dum = ex.dum
lines = []
traces = []
traces1 = []
#indices_to_args_pos = ex._get_indices_to_args_pos()
# TODO: add a dum_to_components_map ?
for p0, p1, c0, c1 in ex.dum_in_args:
if arguments[c0] not in dt:
continue
if c0 == c1:
traces.append([c0])
continue
ta0 = dt[arguments[c0]]
ta1 = dt[arguments[c1]]
if p0 not in ta0:
continue
if ta0.index(p0) == ta1.index(p1):
# case gamma(i,s0,-s1) in c0, gamma(j,-s0,s2) in c1;
# to deal with this case one could add to the position
# a flag for transposition;
# one could write [(c0, False), (c1, True)]
raise NotImplementedError
# if p0 == ta0[1] then G in pos c0 is mult on the right by G in c1
# if p0 == ta0[0] then G in pos c1 is mult on the right by G in c0
ta0 = dt[arguments[c0]]
b0, b1 = (c0, c1) if p0 == ta0[1] else (c1, c0)
lines1 = lines[:]
for line in lines:
if line[-1] == b0:
if line[0] == b1:
n = line.index(min(line))
traces1.append(line)
traces.append(line[n:] + line[:n])
else:
line.append(b1)
break
elif line[0] == b1:
line.insert(0, b0)
break
else:
lines1.append([b0, b1])
lines = [x for x in lines1 if x not in traces1]
lines = _join_lines(lines)
rest = []
for line in lines:
for y in line:
rest.append(y)
for line in traces:
for y in line:
rest.append(y)
rest = [x for x in range(len(arguments)) if x not in rest]
return lines, traces, rest
def get_free_indices(t):
if not isinstance(t, TensExpr):
return ()
return t.get_free_indices()
def get_indices(t):
if not isinstance(t, TensExpr):
return ()
return t.get_indices()
def get_index_structure(t):
if isinstance(t, TensExpr):
return t._index_structure
return _IndexStructure([], [], [], [])
def get_coeff(t):
if isinstance(t, Tensor):
return S.One
if isinstance(t, TensMul):
return t.coeff
if isinstance(t, TensExpr):
raise ValueError("no coefficient associated to this tensor expression")
return t
def contract_metric(t, g):
if isinstance(t, TensExpr):
return t.contract_metric(g)
return t
def perm2tensor(t, g, is_canon_bp=False):
"""
Returns the tensor corresponding to the permutation ``g``
For further details, see the method in ``TIDS`` with the same name.
"""
if not isinstance(t, TensExpr):
return t
elif isinstance(t, (Tensor, TensMul)):
nim = get_index_structure(t).perm2tensor(g, is_canon_bp=is_canon_bp)
res = t._set_new_index_structure(nim, is_canon_bp=is_canon_bp)
if g[-1] != len(g) - 1:
return -res
return res
raise NotImplementedError()
def substitute_indices(t, *index_tuples):
"""
Return a tensor with free indices substituted according to ``index_tuples``
``index_types`` list of tuples ``(old_index, new_index)``
Note: this method will neither raise or lower the indices, it will just replace their symbol.
Examples
========
>>> from sympy.tensor.tensor import TensorIndexType, tensor_indices, tensorhead
>>> Lorentz = TensorIndexType('Lorentz', dummy_fmt='L')
>>> i, j, k, l = tensor_indices('i,j,k,l', Lorentz)
>>> A, B = tensorhead('A,B', [Lorentz]*2, [[1]*2])
>>> t = A(i, k)*B(-k, -j); t
A(i, L_0)*B(-L_0, -j)
>>> t.substitute_indices((i,j), (j, k))
A(j, L_0)*B(-L_0, -k)
"""
if not isinstance(t, TensExpr):
return t
free = t.free
free1 = []
for j, ipos in free:
for i, v in index_tuples:
if i._name == j._name and i.tensor_index_type == j.tensor_index_type:
if i._is_up == j._is_up:
free1.append((v, ipos))
else:
free1.append((-v, ipos))
break
else:
free1.append((j, ipos))
t = TensMul.from_data(t.coeff, t.components, free1, t.dum)
return t
def _expand(expr, **kwargs):
if isinstance(expr, TensExpr):
return expr._expand(**kwargs)
else:
return expr.expand(**kwargs)
|
1946fae399f91149f78b3a318e2517dd14036a4870c2dac50befd5afbf6ed952
|
"""Module with functions operating on IndexedBase, Indexed and Idx objects
- Check shape conformance
- Determine indices in resulting expression
etc.
Methods in this module could be implemented by calling methods on Expr
objects instead. When things stabilize this could be a useful
refactoring.
"""
from __future__ import print_function, division
from sympy.core.compatibility import reduce
from sympy.core.function import Function
from sympy.functions import exp, Piecewise
from sympy.tensor.indexed import Idx, Indexed
from sympy.utilities import sift
from collections import OrderedDict
class IndexConformanceException(Exception):
pass
def _unique_and_repeated(inds):
"""
Returns the unique and repeated indices. Also note, from the examples given below
that the order of indices is maintained as given in the input.
Examples
========
>>> from sympy.tensor.index_methods import _unique_and_repeated
>>> _unique_and_repeated([2, 3, 1, 3, 0, 4, 0])
([2, 1, 4], [3, 0])
"""
uniq = OrderedDict()
for i in inds:
if i in uniq:
uniq[i] = 0
else:
uniq[i] = 1
return sift(uniq, lambda x: uniq[x], binary=True)
def _remove_repeated(inds):
"""
Removes repeated objects from sequences
Returns a set of the unique objects and a tuple of all that have been
removed.
Examples
========
>>> from sympy.tensor.index_methods import _remove_repeated
>>> l1 = [1, 2, 3, 2]
>>> _remove_repeated(l1)
({1, 3}, (2,))
"""
u, r = _unique_and_repeated(inds)
return set(u), tuple(r)
def _get_indices_Mul(expr, return_dummies=False):
"""Determine the outer indices of a Mul object.
Examples
========
>>> from sympy.tensor.index_methods import _get_indices_Mul
>>> from sympy.tensor.indexed import IndexedBase, Idx
>>> i, j, k = map(Idx, ['i', 'j', 'k'])
>>> x = IndexedBase('x')
>>> y = IndexedBase('y')
>>> _get_indices_Mul(x[i, k]*y[j, k])
({i, j}, {})
>>> _get_indices_Mul(x[i, k]*y[j, k], return_dummies=True)
({i, j}, {}, (k,))
"""
inds = list(map(get_indices, expr.args))
inds, syms = list(zip(*inds))
inds = list(map(list, inds))
inds = list(reduce(lambda x, y: x + y, inds))
inds, dummies = _remove_repeated(inds)
symmetry = {}
for s in syms:
for pair in s:
if pair in symmetry:
symmetry[pair] *= s[pair]
else:
symmetry[pair] = s[pair]
if return_dummies:
return inds, symmetry, dummies
else:
return inds, symmetry
def _get_indices_Pow(expr):
"""Determine outer indices of a power or an exponential.
A power is considered a universal function, so that the indices of a Pow is
just the collection of indices present in the expression. This may be
viewed as a bit inconsistent in the special case:
x[i]**2 = x[i]*x[i] (1)
The above expression could have been interpreted as the contraction of x[i]
with itself, but we choose instead to interpret it as a function
lambda y: y**2
applied to each element of x (a universal function in numpy terms). In
order to allow an interpretation of (1) as a contraction, we need
contravariant and covariant Idx subclasses. (FIXME: this is not yet
implemented)
Expressions in the base or exponent are subject to contraction as usual,
but an index that is present in the exponent, will not be considered
contractable with its own base. Note however, that indices in the same
exponent can be contracted with each other.
Examples
========
>>> from sympy.tensor.index_methods import _get_indices_Pow
>>> from sympy import Pow, exp, IndexedBase, Idx
>>> A = IndexedBase('A')
>>> x = IndexedBase('x')
>>> i, j, k = map(Idx, ['i', 'j', 'k'])
>>> _get_indices_Pow(exp(A[i, j]*x[j]))
({i}, {})
>>> _get_indices_Pow(Pow(x[i], x[i]))
({i}, {})
>>> _get_indices_Pow(Pow(A[i, j]*x[j], x[i]))
({i}, {})
"""
base, exp = expr.as_base_exp()
binds, bsyms = get_indices(base)
einds, esyms = get_indices(exp)
inds = binds | einds
# FIXME: symmetries from power needs to check special cases, else nothing
symmetries = {}
return inds, symmetries
def _get_indices_Add(expr):
"""Determine outer indices of an Add object.
In a sum, each term must have the same set of outer indices. A valid
expression could be
x(i)*y(j) - x(j)*y(i)
But we do not allow expressions like:
x(i)*y(j) - z(j)*z(j)
FIXME: Add support for Numpy broadcasting
Examples
========
>>> from sympy.tensor.index_methods import _get_indices_Add
>>> from sympy.tensor.indexed import IndexedBase, Idx
>>> i, j, k = map(Idx, ['i', 'j', 'k'])
>>> x = IndexedBase('x')
>>> y = IndexedBase('y')
>>> _get_indices_Add(x[i] + x[k]*y[i, k])
({i}, {})
"""
inds = list(map(get_indices, expr.args))
inds, syms = list(zip(*inds))
# allow broadcast of scalars
non_scalars = [x for x in inds if x != set()]
if not non_scalars:
return set(), {}
if not all([x == non_scalars[0] for x in non_scalars[1:]]):
raise IndexConformanceException("Indices are not consistent: %s" % expr)
if not reduce(lambda x, y: x != y or y, syms):
symmetries = syms[0]
else:
# FIXME: search for symmetries
symmetries = {}
return non_scalars[0], symmetries
def get_indices(expr):
"""Determine the outer indices of expression ``expr``
By *outer* we mean indices that are not summation indices. Returns a set
and a dict. The set contains outer indices and the dict contains
information about index symmetries.
Examples
========
>>> from sympy.tensor.index_methods import get_indices
>>> from sympy import symbols
>>> from sympy.tensor import IndexedBase, Idx
>>> x, y, A = map(IndexedBase, ['x', 'y', 'A'])
>>> i, j, a, z = symbols('i j a z', integer=True)
The indices of the total expression is determined, Repeated indices imply a
summation, for instance the trace of a matrix A:
>>> get_indices(A[i, i])
(set(), {})
In the case of many terms, the terms are required to have identical
outer indices. Else an IndexConformanceException is raised.
>>> get_indices(x[i] + A[i, j]*y[j])
({i}, {})
:Exceptions:
An IndexConformanceException means that the terms ar not compatible, e.g.
>>> get_indices(x[i] + y[j]) #doctest: +SKIP
(...)
IndexConformanceException: Indices are not consistent: x(i) + y(j)
.. warning::
The concept of *outer* indices applies recursively, starting on the deepest
level. This implies that dummies inside parenthesis are assumed to be
summed first, so that the following expression is handled gracefully:
>>> get_indices((x[i] + A[i, j]*y[j])*x[j])
({i, j}, {})
This is correct and may appear convenient, but you need to be careful
with this as SymPy will happily .expand() the product, if requested. The
resulting expression would mix the outer ``j`` with the dummies inside
the parenthesis, which makes it a different expression. To be on the
safe side, it is best to avoid such ambiguities by using unique indices
for all contractions that should be held separate.
"""
# We call ourself recursively to determine indices of sub expressions.
# break recursion
if isinstance(expr, Indexed):
c = expr.indices
inds, dummies = _remove_repeated(c)
return inds, {}
elif expr is None:
return set(), {}
elif isinstance(expr, Idx):
return {expr}, {}
elif expr.is_Atom:
return set(), {}
# recurse via specialized functions
else:
if expr.is_Mul:
return _get_indices_Mul(expr)
elif expr.is_Add:
return _get_indices_Add(expr)
elif expr.is_Pow or isinstance(expr, exp):
return _get_indices_Pow(expr)
elif isinstance(expr, Piecewise):
# FIXME: No support for Piecewise yet
return set(), {}
elif isinstance(expr, Function):
# Support ufunc like behaviour by returning indices from arguments.
# Functions do not interpret repeated indices across argumnts
# as summation
ind0 = set()
for arg in expr.args:
ind, sym = get_indices(arg)
ind0 |= ind
return ind0, sym
# this test is expensive, so it should be at the end
elif not expr.has(Indexed):
return set(), {}
raise NotImplementedError(
"FIXME: No specialized handling of type %s" % type(expr))
def get_contraction_structure(expr):
"""Determine dummy indices of ``expr`` and describe its structure
By *dummy* we mean indices that are summation indices.
The structure of the expression is determined and described as follows:
1) A conforming summation of Indexed objects is described with a dict where
the keys are summation indices and the corresponding values are sets
containing all terms for which the summation applies. All Add objects
in the SymPy expression tree are described like this.
2) For all nodes in the SymPy expression tree that are *not* of type Add, the
following applies:
If a node discovers contractions in one of its arguments, the node
itself will be stored as a key in the dict. For that key, the
corresponding value is a list of dicts, each of which is the result of a
recursive call to get_contraction_structure(). The list contains only
dicts for the non-trivial deeper contractions, omitting dicts with None
as the one and only key.
.. Note:: The presence of expressions among the dictinary keys indicates
multiple levels of index contractions. A nested dict displays nested
contractions and may itself contain dicts from a deeper level. In
practical calculations the summation in the deepest nested level must be
calculated first so that the outer expression can access the resulting
indexed object.
Examples
========
>>> from sympy.tensor.index_methods import get_contraction_structure
>>> from sympy import symbols, default_sort_key
>>> from sympy.tensor import IndexedBase, Idx
>>> x, y, A = map(IndexedBase, ['x', 'y', 'A'])
>>> i, j, k, l = map(Idx, ['i', 'j', 'k', 'l'])
>>> get_contraction_structure(x[i]*y[i] + A[j, j])
{(i,): {x[i]*y[i]}, (j,): {A[j, j]}}
>>> get_contraction_structure(x[i]*y[j])
{None: {x[i]*y[j]}}
A multiplication of contracted factors results in nested dicts representing
the internal contractions.
>>> d = get_contraction_structure(x[i, i]*y[j, j])
>>> sorted(d.keys(), key=default_sort_key)
[None, x[i, i]*y[j, j]]
In this case, the product has no contractions:
>>> d[None]
{x[i, i]*y[j, j]}
Factors are contracted "first":
>>> sorted(d[x[i, i]*y[j, j]], key=default_sort_key)
[{(i,): {x[i, i]}}, {(j,): {y[j, j]}}]
A parenthesized Add object is also returned as a nested dictionary. The
term containing the parenthesis is a Mul with a contraction among the
arguments, so it will be found as a key in the result. It stores the
dictionary resulting from a recursive call on the Add expression.
>>> d = get_contraction_structure(x[i]*(y[i] + A[i, j]*x[j]))
>>> sorted(d.keys(), key=default_sort_key)
[(A[i, j]*x[j] + y[i])*x[i], (i,)]
>>> d[(i,)]
{(A[i, j]*x[j] + y[i])*x[i]}
>>> d[x[i]*(A[i, j]*x[j] + y[i])]
[{None: {y[i]}, (j,): {A[i, j]*x[j]}}]
Powers with contractions in either base or exponent will also be found as
keys in the dictionary, mapping to a list of results from recursive calls:
>>> d = get_contraction_structure(A[j, j]**A[i, i])
>>> d[None]
{A[j, j]**A[i, i]}
>>> nested_contractions = d[A[j, j]**A[i, i]]
>>> nested_contractions[0]
{(j,): {A[j, j]}}
>>> nested_contractions[1]
{(i,): {A[i, i]}}
The description of the contraction structure may appear complicated when
represented with a string in the above examples, but it is easy to iterate
over:
>>> from sympy import Expr
>>> for key in d:
... if isinstance(key, Expr):
... continue
... for term in d[key]:
... if term in d:
... # treat deepest contraction first
... pass
... # treat outermost contactions here
"""
# We call ourself recursively to inspect sub expressions.
if isinstance(expr, Indexed):
junk, key = _remove_repeated(expr.indices)
return {key or None: {expr}}
elif expr.is_Atom:
return {None: {expr}}
elif expr.is_Mul:
junk, junk, key = _get_indices_Mul(expr, return_dummies=True)
result = {key or None: {expr}}
# recurse on every factor
nested = []
for fac in expr.args:
facd = get_contraction_structure(fac)
if not (None in facd and len(facd) == 1):
nested.append(facd)
if nested:
result[expr] = nested
return result
elif expr.is_Pow or isinstance(expr, exp):
# recurse in base and exp separately. If either has internal
# contractions we must include ourselves as a key in the returned dict
b, e = expr.as_base_exp()
dbase = get_contraction_structure(b)
dexp = get_contraction_structure(e)
dicts = []
for d in dbase, dexp:
if not (None in d and len(d) == 1):
dicts.append(d)
result = {None: {expr}}
if dicts:
result[expr] = dicts
return result
elif expr.is_Add:
# Note: we just collect all terms with identical summation indices, We
# do nothing to identify equivalent terms here, as this would require
# substitutions or pattern matching in expressions of unknown
# complexity.
result = {}
for term in expr.args:
# recurse on every term
d = get_contraction_structure(term)
for key in d:
if key in result:
result[key] |= d[key]
else:
result[key] = d[key]
return result
elif isinstance(expr, Piecewise):
# FIXME: No support for Piecewise yet
return {None: expr}
elif isinstance(expr, Function):
# Collect non-trivial contraction structures in each argument
# We do not report repeated indices in separate arguments as a
# contraction
deeplist = []
for arg in expr.args:
deep = get_contraction_structure(arg)
if not (None in deep and len(deep) == 1):
deeplist.append(deep)
d = {None: {expr}}
if deeplist:
d[expr] = deeplist
return d
# this test is expensive, so it should be at the end
elif not expr.has(Indexed):
return {None: {expr}}
raise NotImplementedError(
"FIXME: No specialized handling of type %s" % type(expr))
|
15dcf9c231ae804cec4ca73cb3e5dea19b27ac8a367534c540edcde94f2c89eb
|
from sympy import Expr, S, Mul, sympify
from sympy.core.compatibility import Iterable
from sympy.core.evaluate import global_evaluate
class TensorProduct(Expr):
"""
Generic class for tensor products.
"""
is_number = False
def __new__(cls, *args, **kwargs):
from sympy.tensor.array import NDimArray, tensorproduct, Array
from sympy import MatrixBase, MatrixExpr
from sympy.strategies import flatten
args = [sympify(arg) for arg in args]
evaluate = kwargs.get("evaluate", global_evaluate[0])
if not evaluate:
obj = Expr.__new__(cls, *args)
return obj
arrays = []
other = []
scalar = S.One
for arg in args:
if isinstance(arg, (Iterable, MatrixBase, NDimArray)):
arrays.append(Array(arg))
elif isinstance(arg, (MatrixExpr,)):
other.append(arg)
else:
scalar *= arg
coeff = scalar*tensorproduct(*arrays)
if len(other) == 0:
return coeff
if coeff != 1:
newargs = [coeff] + other
else:
newargs = other
obj = Expr.__new__(cls, *newargs, **kwargs)
return flatten(obj)
def rank(self):
return len(self.shape)
def _get_args_shapes(self):
from sympy import Array
return [i.shape if hasattr(i, "shape") else Array(i).shape for i in self.args]
@property
def shape(self):
shape_list = self._get_args_shapes()
return sum(shape_list, ())
def __getitem__(self, index):
index = iter(index)
return Mul.fromiter(
arg.__getitem__(tuple(next(index) for i in shp))
for arg, shp in zip(self.args, self._get_args_shapes())
)
|
2ba3eb364f1786e66114a1cbf67fc73c5606ece633ad62d32e3a574a82b929d3
|
r"""Module that defines indexed objects
The classes ``IndexedBase``, ``Indexed``, and ``Idx`` represent a
matrix element ``M[i, j]`` as in the following diagram::
1) The Indexed class represents the entire indexed object.
|
___|___
' '
M[i, j]
/ \__\______
| |
| |
| 2) The Idx class represents indices; each Idx can
| optionally contain information about its range.
|
3) IndexedBase represents the 'stem' of an indexed object, here `M`.
The stem used by itself is usually taken to represent the entire
array.
There can be any number of indices on an Indexed object. No
transformation properties are implemented in these Base objects, but
implicit contraction of repeated indices is supported.
Note that the support for complicated (i.e. non-atomic) integer
expressions as indices is limited. (This should be improved in
future releases.)
Examples
========
To express the above matrix element example you would write:
>>> from sympy import symbols, IndexedBase, Idx
>>> M = IndexedBase('M')
>>> i, j = symbols('i j', cls=Idx)
>>> M[i, j]
M[i, j]
Repeated indices in a product implies a summation, so to express a
matrix-vector product in terms of Indexed objects:
>>> x = IndexedBase('x')
>>> M[i, j]*x[j]
M[i, j]*x[j]
If the indexed objects will be converted to component based arrays, e.g.
with the code printers or the autowrap framework, you also need to provide
(symbolic or numerical) dimensions. This can be done by passing an
optional shape parameter to IndexedBase upon construction:
>>> dim1, dim2 = symbols('dim1 dim2', integer=True)
>>> A = IndexedBase('A', shape=(dim1, 2*dim1, dim2))
>>> A.shape
(dim1, 2*dim1, dim2)
>>> A[i, j, 3].shape
(dim1, 2*dim1, dim2)
If an IndexedBase object has no shape information, it is assumed that the
array is as large as the ranges of its indices:
>>> n, m = symbols('n m', integer=True)
>>> i = Idx('i', m)
>>> j = Idx('j', n)
>>> M[i, j].shape
(m, n)
>>> M[i, j].ranges
[(0, m - 1), (0, n - 1)]
The above can be compared with the following:
>>> A[i, 2, j].shape
(dim1, 2*dim1, dim2)
>>> A[i, 2, j].ranges
[(0, m - 1), None, (0, n - 1)]
To analyze the structure of indexed expressions, you can use the methods
get_indices() and get_contraction_structure():
>>> from sympy.tensor import get_indices, get_contraction_structure
>>> get_indices(A[i, j, j])
({i}, {})
>>> get_contraction_structure(A[i, j, j])
{(j,): {A[i, j, j]}}
See the appropriate docstrings for a detailed explanation of the output.
"""
# TODO: (some ideas for improvement)
#
# o test and guarantee numpy compatibility
# - implement full support for broadcasting
# - strided arrays
#
# o more functions to analyze indexed expressions
# - identify standard constructs, e.g matrix-vector product in a subexpression
#
# o functions to generate component based arrays (numpy and sympy.Matrix)
# - generate a single array directly from Indexed
# - convert simple sub-expressions
#
# o sophisticated indexing (possibly in subclasses to preserve simplicity)
# - Idx with range smaller than dimension of Indexed
# - Idx with stepsize != 1
# - Idx with step determined by function call
from __future__ import print_function, division
from sympy.core import Expr, Tuple, Symbol, sympify, S
from sympy.core.compatibility import (is_sequence, string_types, NotIterable,
Iterable)
from sympy.core.sympify import _sympify
from sympy.functions.special.tensor_functions import KroneckerDelta
class IndexException(Exception):
pass
class Indexed(Expr):
"""Represents a mathematical object with indices.
>>> from sympy import Indexed, IndexedBase, Idx, symbols
>>> i, j = symbols('i j', cls=Idx)
>>> Indexed('A', i, j)
A[i, j]
It is recommended that ``Indexed`` objects be created via ``IndexedBase``:
>>> A = IndexedBase('A')
>>> Indexed('A', i, j) == A[i, j]
True
"""
is_commutative = True
is_Indexed = True
is_symbol = True
is_Atom = True
def __new__(cls, base, *args, **kw_args):
from sympy.utilities.misc import filldedent
from sympy.tensor.array.ndim_array import NDimArray
from sympy.matrices.matrices import MatrixBase
if not args:
raise IndexException("Indexed needs at least one index.")
if isinstance(base, (string_types, Symbol)):
base = IndexedBase(base)
elif not hasattr(base, '__getitem__') and not isinstance(base, IndexedBase):
raise TypeError(filldedent("""
Indexed expects string, Symbol, or IndexedBase as base."""))
args = list(map(sympify, args))
if isinstance(base, (NDimArray, Iterable, Tuple, MatrixBase)) and all([i.is_number for i in args]):
if len(args) == 1:
return base[args[0]]
else:
return base[args]
return Expr.__new__(cls, base, *args, **kw_args)
@property
def name(self):
return str(self)
@property
def _diff_wrt(self):
"""Allow derivatives with respect to an ``Indexed`` object."""
return True
def _eval_derivative(self, wrt):
from sympy.tensor.array.ndim_array import NDimArray
if isinstance(wrt, Indexed) and wrt.base == self.base:
if len(self.indices) != len(wrt.indices):
msg = "Different # of indices: d({!s})/d({!s})".format(self,
wrt)
raise IndexException(msg)
result = S.One
for index1, index2 in zip(self.indices, wrt.indices):
result *= KroneckerDelta(index1, index2)
return result
elif isinstance(self.base, NDimArray):
from sympy.tensor.array import derive_by_array
return Indexed(derive_by_array(self.base, wrt), *self.args[1:])
else:
if Tuple(self.indices).has(wrt):
return S.NaN
return S.Zero
@property
def base(self):
"""Returns the ``IndexedBase`` of the ``Indexed`` object.
Examples
========
>>> from sympy import Indexed, IndexedBase, Idx, symbols
>>> i, j = symbols('i j', cls=Idx)
>>> Indexed('A', i, j).base
A
>>> B = IndexedBase('B')
>>> B == B[i, j].base
True
"""
return self.args[0]
@property
def indices(self):
"""
Returns the indices of the ``Indexed`` object.
Examples
========
>>> from sympy import Indexed, Idx, symbols
>>> i, j = symbols('i j', cls=Idx)
>>> Indexed('A', i, j).indices
(i, j)
"""
return self.args[1:]
@property
def rank(self):
"""
Returns the rank of the ``Indexed`` object.
Examples
========
>>> from sympy import Indexed, Idx, symbols
>>> i, j, k, l, m = symbols('i:m', cls=Idx)
>>> Indexed('A', i, j).rank
2
>>> q = Indexed('A', i, j, k, l, m)
>>> q.rank
5
>>> q.rank == len(q.indices)
True
"""
return len(self.args) - 1
@property
def shape(self):
"""Returns a list with dimensions of each index.
Dimensions is a property of the array, not of the indices. Still, if
the ``IndexedBase`` does not define a shape attribute, it is assumed
that the ranges of the indices correspond to the shape of the array.
>>> from sympy import IndexedBase, Idx, symbols
>>> n, m = symbols('n m', integer=True)
>>> i = Idx('i', m)
>>> j = Idx('j', m)
>>> A = IndexedBase('A', shape=(n, n))
>>> B = IndexedBase('B')
>>> A[i, j].shape
(n, n)
>>> B[i, j].shape
(m, m)
"""
from sympy.utilities.misc import filldedent
if self.base.shape:
return self.base.shape
try:
return Tuple(*[i.upper - i.lower + 1 for i in self.indices])
except AttributeError:
raise IndexException(filldedent("""
Range is not defined for all indices in: %s""" % self))
except TypeError:
raise IndexException(filldedent("""
Shape cannot be inferred from Idx with
undefined range: %s""" % self))
@property
def ranges(self):
"""Returns a list of tuples with lower and upper range of each index.
If an index does not define the data members upper and lower, the
corresponding slot in the list contains ``None`` instead of a tuple.
Examples
========
>>> from sympy import Indexed,Idx, symbols
>>> Indexed('A', Idx('i', 2), Idx('j', 4), Idx('k', 8)).ranges
[(0, 1), (0, 3), (0, 7)]
>>> Indexed('A', Idx('i', 3), Idx('j', 3), Idx('k', 3)).ranges
[(0, 2), (0, 2), (0, 2)]
>>> x, y, z = symbols('x y z', integer=True)
>>> Indexed('A', x, y, z).ranges
[None, None, None]
"""
ranges = []
for i in self.indices:
try:
ranges.append(Tuple(i.lower, i.upper))
except AttributeError:
ranges.append(None)
return ranges
def _sympystr(self, p):
indices = list(map(p.doprint, self.indices))
return "%s[%s]" % (p.doprint(self.base), ", ".join(indices))
@property
def free_symbols(self):
base_free_symbols = self.base.free_symbols
indices_free_symbols = {
fs for i in self.indices for fs in i.free_symbols}
if base_free_symbols:
return {self} | base_free_symbols | indices_free_symbols
else:
return indices_free_symbols
@property
def expr_free_symbols(self):
return {self}
class IndexedBase(Expr, NotIterable):
"""Represent the base or stem of an indexed object
The IndexedBase class represent an array that contains elements. The main purpose
of this class is to allow the convenient creation of objects of the Indexed
class. The __getitem__ method of IndexedBase returns an instance of
Indexed. Alone, without indices, the IndexedBase class can be used as a
notation for e.g. matrix equations, resembling what you could do with the
Symbol class. But, the IndexedBase class adds functionality that is not
available for Symbol instances:
- An IndexedBase object can optionally store shape information. This can
be used in to check array conformance and conditions for numpy
broadcasting. (TODO)
- An IndexedBase object implements syntactic sugar that allows easy symbolic
representation of array operations, using implicit summation of
repeated indices.
- The IndexedBase object symbolizes a mathematical structure equivalent
to arrays, and is recognized as such for code generation and automatic
compilation and wrapping.
>>> from sympy.tensor import IndexedBase, Idx
>>> from sympy import symbols
>>> A = IndexedBase('A'); A
A
>>> type(A)
<class 'sympy.tensor.indexed.IndexedBase'>
When an IndexedBase object receives indices, it returns an array with named
axes, represented by an Indexed object:
>>> i, j = symbols('i j', integer=True)
>>> A[i, j, 2]
A[i, j, 2]
>>> type(A[i, j, 2])
<class 'sympy.tensor.indexed.Indexed'>
The IndexedBase constructor takes an optional shape argument. If given,
it overrides any shape information in the indices. (But not the index
ranges!)
>>> m, n, o, p = symbols('m n o p', integer=True)
>>> i = Idx('i', m)
>>> j = Idx('j', n)
>>> A[i, j].shape
(m, n)
>>> B = IndexedBase('B', shape=(o, p))
>>> B[i, j].shape
(o, p)
"""
is_commutative = True
is_symbol = True
is_Atom = True
def __new__(cls, label, shape=None, **kw_args):
from sympy import MatrixBase, NDimArray
if isinstance(label, string_types):
label = Symbol(label)
elif isinstance(label, Symbol):
pass
elif isinstance(label, (MatrixBase, NDimArray)):
return label
elif isinstance(label, Iterable):
return _sympify(label)
else:
label = _sympify(label)
if is_sequence(shape):
shape = Tuple(*shape)
elif shape is not None:
shape = Tuple(shape)
offset = kw_args.pop('offset', S.Zero)
strides = kw_args.pop('strides', None)
if shape is not None:
obj = Expr.__new__(cls, label, shape)
else:
obj = Expr.__new__(cls, label)
obj._shape = shape
obj._offset = offset
obj._strides = strides
obj._name = str(label)
return obj
@property
def name(self):
return self._name
def __getitem__(self, indices, **kw_args):
if is_sequence(indices):
# Special case needed because M[*my_tuple] is a syntax error.
if self.shape and len(self.shape) != len(indices):
raise IndexException("Rank mismatch.")
return Indexed(self, *indices, **kw_args)
else:
if self.shape and len(self.shape) != 1:
raise IndexException("Rank mismatch.")
return Indexed(self, indices, **kw_args)
@property
def shape(self):
"""Returns the shape of the ``IndexedBase`` object.
Examples
========
>>> from sympy import IndexedBase, Idx, Symbol
>>> from sympy.abc import x, y
>>> IndexedBase('A', shape=(x, y)).shape
(x, y)
Note: If the shape of the ``IndexedBase`` is specified, it will override
any shape information given by the indices.
>>> A = IndexedBase('A', shape=(x, y))
>>> B = IndexedBase('B')
>>> i = Idx('i', 2)
>>> j = Idx('j', 1)
>>> A[i, j].shape
(x, y)
>>> B[i, j].shape
(2, 1)
"""
return self._shape
@property
def strides(self):
"""Returns the strided scheme for the ``IndexedBase`` object.
Normally this is a tuple denoting the number of
steps to take in the respective dimension when traversing
an array. For code generation purposes strides='C' and
strides='F' can also be used.
strides='C' would mean that code printer would unroll
in row-major order and 'F' means unroll in column major
order.
"""
return self._strides
@property
def offset(self):
"""Returns the offset for the ``IndexedBase`` object.
This is the value added to the resulting index when the
2D Indexed object is unrolled to a 1D form. Used in code
generation.
Examples
==========
>>> from sympy.printing import ccode
>>> from sympy.tensor import IndexedBase, Idx
>>> from sympy import symbols
>>> l, m, n, o = symbols('l m n o', integer=True)
>>> A = IndexedBase('A', strides=(l, m, n), offset=o)
>>> i, j, k = map(Idx, 'ijk')
>>> ccode(A[i, j, k])
'A[l*i + m*j + n*k + o]'
"""
return self._offset
@property
def label(self):
"""Returns the label of the ``IndexedBase`` object.
Examples
========
>>> from sympy import IndexedBase
>>> from sympy.abc import x, y
>>> IndexedBase('A', shape=(x, y)).label
A
"""
return self.args[0]
def _sympystr(self, p):
return p.doprint(self.label)
class Idx(Expr):
"""Represents an integer index as an ``Integer`` or integer expression.
There are a number of ways to create an ``Idx`` object. The constructor
takes two arguments:
``label``
An integer or a symbol that labels the index.
``range``
Optionally you can specify a range as either
* ``Symbol`` or integer: This is interpreted as a dimension. Lower and
upper bounds are set to ``0`` and ``range - 1``, respectively.
* ``tuple``: The two elements are interpreted as the lower and upper
bounds of the range, respectively.
Note: bounds of the range are assumed to be either integer or infinite (oo
and -oo are allowed to specify an unbounded range). If ``n`` is given as a
bound, then ``n.is_integer`` must not return false.
For convenience, if the label is given as a string it is automatically
converted to an integer symbol. (Note: this conversion is not done for
range or dimension arguments.)
Examples
========
>>> from sympy import IndexedBase, Idx, symbols, oo
>>> n, i, L, U = symbols('n i L U', integer=True)
If a string is given for the label an integer ``Symbol`` is created and the
bounds are both ``None``:
>>> idx = Idx('qwerty'); idx
qwerty
>>> idx.lower, idx.upper
(None, None)
Both upper and lower bounds can be specified:
>>> idx = Idx(i, (L, U)); idx
i
>>> idx.lower, idx.upper
(L, U)
When only a single bound is given it is interpreted as the dimension
and the lower bound defaults to 0:
>>> idx = Idx(i, n); idx.lower, idx.upper
(0, n - 1)
>>> idx = Idx(i, 4); idx.lower, idx.upper
(0, 3)
>>> idx = Idx(i, oo); idx.lower, idx.upper
(0, oo)
"""
is_integer = True
is_finite = True
is_real = True
is_symbol = True
is_Atom = True
_diff_wrt = True
def __new__(cls, label, range=None, **kw_args):
from sympy.utilities.misc import filldedent
if isinstance(label, string_types):
label = Symbol(label, integer=True)
label, range = list(map(sympify, (label, range)))
if label.is_Number:
if not label.is_integer:
raise TypeError("Index is not an integer number.")
return label
if not label.is_integer:
raise TypeError("Idx object requires an integer label.")
elif is_sequence(range):
if len(range) != 2:
raise ValueError(filldedent("""
Idx range tuple must have length 2, but got %s""" % len(range)))
for bound in range:
if bound.is_integer is False:
raise TypeError("Idx object requires integer bounds.")
args = label, Tuple(*range)
elif isinstance(range, Expr):
if not (range.is_integer or range is S.Infinity):
raise TypeError("Idx object requires an integer dimension.")
args = label, Tuple(0, range - 1)
elif range:
raise TypeError(filldedent("""
The range must be an ordered iterable or
integer SymPy expression."""))
else:
args = label,
obj = Expr.__new__(cls, *args, **kw_args)
obj._assumptions["finite"] = True
obj._assumptions["real"] = True
return obj
@property
def label(self):
"""Returns the label (Integer or integer expression) of the Idx object.
Examples
========
>>> from sympy import Idx, Symbol
>>> x = Symbol('x', integer=True)
>>> Idx(x).label
x
>>> j = Symbol('j', integer=True)
>>> Idx(j).label
j
>>> Idx(j + 1).label
j + 1
"""
return self.args[0]
@property
def lower(self):
"""Returns the lower bound of the ``Idx``.
Examples
========
>>> from sympy import Idx
>>> Idx('j', 2).lower
0
>>> Idx('j', 5).lower
0
>>> Idx('j').lower is None
True
"""
try:
return self.args[1][0]
except IndexError:
return
@property
def upper(self):
"""Returns the upper bound of the ``Idx``.
Examples
========
>>> from sympy import Idx
>>> Idx('j', 2).upper
1
>>> Idx('j', 5).upper
4
>>> Idx('j').upper is None
True
"""
try:
return self.args[1][1]
except IndexError:
return
def _sympystr(self, p):
return p.doprint(self.label)
@property
def name(self):
return self.label.name if self.label.is_Symbol else str(self.label)
@property
def free_symbols(self):
return {self}
def __le__(self, other):
if isinstance(other, Idx):
other_upper = other if other.upper is None else other.upper
other_lower = other if other.lower is None else other.lower
else:
other_upper = other
other_lower = other
if self.upper is not None and (self.upper <= other_lower) == True:
return True
if self.lower is not None and (self.lower > other_upper) == True:
return False
return super(Idx, self).__le__(other)
def __ge__(self, other):
if isinstance(other, Idx):
other_upper = other if other.upper is None else other.upper
other_lower = other if other.lower is None else other.lower
else:
other_upper = other
other_lower = other
if self.lower is not None and (self.lower >= other_upper) == True:
return True
if self.upper is not None and (self.upper < other_lower) == True:
return False
return super(Idx, self).__ge__(other)
def __lt__(self, other):
if isinstance(other, Idx):
other_upper = other if other.upper is None else other.upper
other_lower = other if other.lower is None else other.lower
else:
other_upper = other
other_lower = other
if self.upper is not None and (self.upper < other_lower) == True:
return True
if self.lower is not None and (self.lower >= other_upper) == True:
return False
return super(Idx, self).__lt__(other)
def __gt__(self, other):
if isinstance(other, Idx):
other_upper = other if other.upper is None else other.upper
other_lower = other if other.lower is None else other.lower
else:
other_upper = other
other_lower = other
if self.lower is not None and (self.lower > other_upper) == True:
return True
if self.upper is not None and (self.upper <= other_lower) == True:
return False
return super(Idx, self).__gt__(other)
|
a84fecf20c0741a70f03311dc76e2c2d9215daa2731de42d3542a8e0914d6468
|
"""
Basic methods common to all matrices to be used
when creating more advanced matrices (e.g., matrices over rings,
etc.).
"""
from __future__ import print_function, division
from sympy.core.add import Add
from sympy.core.basic import Basic, Atom
from sympy.core.expr import Expr
from sympy.core.symbol import Symbol
from sympy.core.function import count_ops
from sympy.core.singleton import S
from sympy.core.sympify import sympify
from sympy.core.compatibility import is_sequence, default_sort_key, range, \
NotIterable, Iterable
from sympy.simplify import simplify as _simplify, signsimp, nsimplify
from sympy.utilities.iterables import flatten
from sympy.functions import Abs
from sympy.core.compatibility import reduce, as_int, string_types
from sympy.assumptions.refine import refine
from sympy.core.decorators import call_highest_priority
from types import FunctionType
from collections import defaultdict
class MatrixError(Exception):
pass
class ShapeError(ValueError, MatrixError):
"""Wrong matrix shape"""
pass
class NonSquareMatrixError(ShapeError):
pass
class MatrixRequired(object):
"""All subclasses of matrix objects must implement the
required matrix properties listed here."""
rows = None
cols = None
shape = None
_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.")
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):
cols = self.cols
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_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 col_del(self, col):
"""Delete the specified column."""
if col < 0:
col += self.cols
if not 0 <= col < self.cols:
raise ValueError("Column {} 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_op
col_swap
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 ValueError("Row {} 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 row(self, i):
"""Elementary row selector.
Examples
========
>>> from sympy import eye
>>> eye(2).row(0)
Matrix([[1, 0]])
See Also
========
col
row_op
row_swap
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 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 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()
@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):
def entry(i, j):
return S.One if i == j else S.Zero
return cls._new(rows, cols, entry)
@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 S.One
return S.Zero
else:
def entry(i, j):
if i == j:
return eigenvalue
elif i + 1 == j:
return S.One
return S.Zero
return cls._new(rows, cols, entry)
@classmethod
def _eval_ones(cls, rows, cols):
def entry(i, j):
return S.One
return cls._new(rows, cols, entry)
@classmethod
def _eval_zeros(cls, rows, cols):
def entry(i, j):
return S.Zero
return cls._new(rows, cols, entry)
@classmethod
def diag(kls, *args, **kwargs):
"""Returns a matrix with the specified diagonal.
If matrices are passed, a block-diagonal matrix
is created.
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
Examples
========
>>> from sympy.matrices import Matrix
>>> Matrix.diag(1, 2, 3)
Matrix([
[1, 0, 0],
[0, 2, 0],
[0, 0, 3]])
>>> Matrix.diag([1, 2, 3])
Matrix([
[1, 0, 0],
[0, 2, 0],
[0, 0, 3]])
The diagonal elements can be matrices; diagonal filling will
continue on the diagonal from the last element of the matrix:
>>> from sympy.abc import x, y, z
>>> a = Matrix([x, y, z])
>>> b = Matrix([[1, 2], [3, 4]])
>>> c = Matrix([[5, 6]])
>>> Matrix.diag(a, 7, b, c)
Matrix([
[x, 0, 0, 0, 0, 0],
[y, 0, 0, 0, 0, 0],
[z, 0, 0, 0, 0, 0],
[0, 7, 0, 0, 0, 0],
[0, 0, 1, 2, 0, 0],
[0, 0, 3, 4, 0, 0],
[0, 0, 0, 0, 5, 6]])
A given band off the diagonal can be made by padding with a
vertical or horizontal "kerning" vector:
>>> hpad = Matrix(0, 2, [])
>>> vpad = Matrix(2, 0, [])
>>> Matrix.diag(vpad, 1, 2, 3, hpad) + Matrix.diag(hpad, 4, 5, 6, vpad)
Matrix([
[0, 0, 4, 0, 0],
[0, 0, 0, 5, 0],
[1, 0, 0, 0, 6],
[0, 2, 0, 0, 0],
[0, 0, 3, 0, 0]])
The type of the resulting matrix can be affected with the ``cls``
keyword.
>>> type(Matrix.diag(1))
<class 'sympy.matrices.dense.MutableDenseMatrix'>
>>> from sympy.matrices import ImmutableMatrix
>>> type(Matrix.diag(1, cls=ImmutableMatrix))
<class 'sympy.matrices.immutable.ImmutableDenseMatrix'>
"""
klass = kwargs.get('cls', kls)
# allow a sequence to be passed in as the only argument
if len(args) == 1 and is_sequence(args[0]) and not getattr(args[0], 'is_Matrix', False):
args = args[0]
def size(m):
"""Compute the size of the diagonal block"""
if hasattr(m, 'rows'):
return m.rows, m.cols
return 1, 1
diag_rows = sum(size(m)[0] for m in args)
diag_cols = sum(size(m)[1] for m in args)
rows = kwargs.get('rows', diag_rows)
cols = kwargs.get('cols', diag_cols)
if rows < diag_rows or cols < diag_cols:
raise ValueError("A {} x {} diagnal matrix cannot accommodate a"
"diagonal of size at least {} x {}.".format(rows, cols,
diag_rows, diag_cols))
# fill a default dict with the diagonal entries
diag_entries = defaultdict(lambda: S.Zero)
row_pos, col_pos = 0, 0
for m in args:
if hasattr(m, 'rows'):
# in this case, we're a matrix
for i in range(m.rows):
for j in range(m.cols):
diag_entries[(i + row_pos, j + col_pos)] = m[i, j]
row_pos += m.rows
col_pos += m.cols
else:
# in this case, we're a single value
diag_entries[(row_pos, col_pos)] = m
row_pos += 1
col_pos += 1
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
klass = kwargs.get('cls', kls)
rows, cols = as_int(rows), as_int(cols)
return klass._eval_eye(rows, cols)
@classmethod
def jordan_block(kls, *args, **kwargs):
"""Returns a Jordan block with the specified size
and eigenvalue. You may call `jordan_block` with
two args (size, eigenvalue) or with keyword arguments.
kwargs
======
size : rows and columns of the matrix
rows : rows of the matrix (if None, rows=size)
cols : cols of the matrix (if None, cols=size)
eigenvalue : value on the diagonal of the matrix
band : position of off-diagonal 1s. May be 'upper' or
'lower'. (Default: 'upper')
cls : class of the returned matrix
Examples
========
>>> 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]])
>>> Matrix.jordan_block(4, x, band='lower')
Matrix([
[x, 0, 0, 0],
[1, x, 0, 0],
[0, 1, x, 0],
[0, 0, 1, x]])
>>> Matrix.jordan_block(size=4, eigenvalue=x)
Matrix([
[x, 1, 0, 0],
[0, x, 1, 0],
[0, 0, x, 1],
[0, 0, 0, x]])
"""
klass = kwargs.get('cls', kls)
size, eigenvalue = None, None
if len(args) == 2:
size, eigenvalue = args
elif len(args) == 1:
size = args[0]
elif len(args) != 0:
raise ValueError("'jordan_block' accepts 0, 1, or 2 arguments, not {}".format(len(args)))
rows, cols = kwargs.get('rows', None), kwargs.get('cols', None)
size = kwargs.get('size', size)
band = kwargs.get('band', 'upper')
# allow for a shortened form of `eigenvalue`
eigenvalue = kwargs.get('eigenval', eigenvalue)
eigenvalue = kwargs.get('eigenvalue', eigenvalue)
if eigenvalue is None:
raise ValueError("Must supply an eigenvalue")
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
klass = kwargs.get('cls', kls)
rows, cols = as_int(rows), as_int(cols)
return klass._eval_zeros(rows, cols)
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))
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
def _eval_is_Identity(self):
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
def _eval_is_zero(self):
if any(i.is_zero == False for i in self):
return False
if any(i.is_zero == 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 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}
"""
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 isinstance(simplify, FunctionType):
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
is_diagonalizable
diagonalize
"""
return self._eval_is_diagonal()
@property
def is_hermitian(self, simplify=True):
"""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
simpfunc = simplify
if not isinstance(simplify, FunctionType):
simpfunc = _simplify if simplify else lambda x: x
return self._eval_is_matrix_hermitian(simpfunc)
@property
def is_Identity(self):
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 isinstance(simplify, FunctionType):
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(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
True
>>> b.is_zero
True
>>> c.is_zero
False
>>> d.is_zero
True
>>> e.is_zero
"""
return self._eval_is_zero()
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):
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):
"""Returns a tuple containing the (real, imaginary) part of matrix."""
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
D: Dirac conjugation
"""
return self._eval_conjugate()
def doit(self, **kwargs):
return self.applyfunc(lambda x: x.doit())
def evalf(self, prec=None, **options):
"""Apply evalf() to each element of self."""
return self.applyfunc(lambda i: i.evalf(prec, **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
D: Dirac conjugation
"""
return self.T.C
def permute(self, perm, orientation='rows', direction='forward'):
"""Permute the rows or columns of a matrix by the given list of swaps.
Parameters
==========
perm : a permutation. This may be a list swaps (e.g., `[[1, 2], [0, 3]]`),
or any valid input to the `Permutation` constructor, including a `Permutation()`
itself. If `perm` is given explicitly as a list of indices or a `Permutation`,
`direction` has no effect.
orientation : ('rows' or 'cols') whether to permute the rows or the columns
direction : ('forward', 'backward') whether to apply the permutations from
the start of the list first, or from the back of the list first
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]])
"""
# 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))
# 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.")
# see if we are a list of pairs
try:
assert len(perm[0]) == 2
# we are a list of swaps, so `direction` matters
if direction == 'backward':
perm = reversed(perm)
# since Permutation doesn't let us have non-disjoint cycles,
# we'll construct the explicit mapping ourselves XXX Bug #12479
mapping = list(range(max_index))
for (i, j) in perm:
mapping[i], mapping[j] = mapping[j], mapping[i]
perm = mapping
except (TypeError, AssertionError, IndexError):
pass
from sympy.combinatorics import Permutation
perm = Permutation(perm, size=max_index)
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):
"""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))
def simplify(self, ratio=1.7, measure=count_ops, rational=False, inverse=False):
"""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(ratio=ratio, measure=measure,
rational=rational, inverse=inverse))
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]])
"""
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 not 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()
T = property(transpose, None, None, "Matrix transposition.")
C = property(conjugate, None, None, "By-element conjugation.")
n = evalf
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))
_eval_simplify = simplify
def _eval_trigsimp(self, **opts):
from sympy.simplify import trigsimp
return self.applyfunc(lambda x: trigsimp(x, **opts))
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):
try:
return sum(self[i,k]*other[k,j] for k in range(self.cols))
except TypeError:
# Block matrices don't work with `sum` or `Add` (ISSUE #11599)
# They don't work with `sum` because `sum` tries to add `0`
# initially, and for a matrix, that is a mix of a scalar and
# a matrix, which raises a TypeError. Fall back to a
# block-matrix-safe way to multiply if the `sum` fails.
ret = self[i, 0]*other[0, j]
for k in range(1, self.cols):
ret += self[i, k]*other[k, j]
return ret
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:
return self * self._eval_pow_by_recursion(num - 1)
ret = self._eval_pow_by_recursion(num // 2)
return ret * ret
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."""
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('__rdiv__')
def __div__(self, other):
return self * (S.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)
@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
"""
other = _matrixify(other)
# matrix-like objects can have shapes. This is
# our first sanity check.
if hasattr(other, 'shape') and len(other.shape) == 2:
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):
return self._eval_matrix_mul(other)
# 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 __neg__(self):
return self._eval_scalar_mul(-1)
@call_highest_priority('__rpow__')
def __pow__(self, num):
if not self.rows == self.cols:
raise NonSquareMatrixError()
try:
a = self
num = sympify(num)
if num.is_Number and num % 1 == 0:
if a.rows == 1:
return a._new([[a[0]**num]])
if num == 0:
return self._new(self.rows, self.cols, lambda i, j: int(i == j))
if num < 0:
num = -num
a = a.inv()
# When certain conditions are met,
# Jordan block algorithm is faster than
# computation by recursion.
elif a.rows == 2 and num > 100000:
try:
return a._matrix_pow_by_jordan_blocks(num)
except (AttributeError, MatrixError):
pass
return a._eval_pow_by_recursion(num)
elif num.is_Number != True and num.is_negative == None and a.det() == 0:
from sympy.matrices.expressions import MatPow
return MatPow(a, num)
elif isinstance(num, (Expr, float)):
return a._matrix_pow_by_jordan_blocks(num)
else:
raise TypeError(
"Only SymPy expressions or integers are supported as exponent for matrices")
except AttributeError:
raise TypeError("Don't know how to raise {} to {}".format(self.__class__, num))
@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):
other = _matrixify(other)
# matrix-like objects can have shapes. This is
# our first sanity check.
if hasattr(other, 'shape') and len(other.shape) == 2:
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):
return other._new(other.as_mutable() * self)
# 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)
@call_highest_priority('__rtruediv__')
def __truediv__(self, other):
return self.__div__(other)
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
========
cross
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)
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
class _MinimalMatrix(object):
"""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
is_Matrix = True
is_MatrixExpr = False
@classmethod
def _new(cls, *args, **kwargs):
return cls(*args, **kwargs)
def __init__(self, rows, cols=None, mat=None):
if isinstance(mat, FunctionType):
# 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))
try:
if cols is None and mat is None:
mat = rows
rows, cols = mat.shape
except AttributeError:
pass
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):
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 _MatrixWrapper(object):
"""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. For example, wrapping a numpy
matrix in a MatrixWrapper allows it to be passed to CommonMatrix.
"""
is_MatrixLike = True
def __init__(self, mat, shape=None):
self.mat = mat
self.rows, self.cols = mat.shape if shape is None else shape
def __getattr__(self, attr):
"""Most attribute access is passed straight through
to the stored matrix"""
return getattr(self.mat, attr)
def __getitem__(self, key):
return self.mat.__getitem__(key)
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):
return mat
if hasattr(mat, 'shape'):
if len(mat.shape) == 2:
return _MatrixWrapper(mat)
return mat
def a2idx(j, n=None):
"""Return integer after making positive and validating against n."""
if type(j) is not int:
try:
j = j.__index__()
except AttributeError:
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'>
"""
try:
if A._class_priority > B._class_priority:
return A.__class__
else:
return B.__class__
except AttributeError:
pass
try:
import numpy
if isinstance(A, numpy.ndarray):
return B.__class__
if isinstance(B, numpy.ndarray):
return A.__class__
except (AttributeError, ImportError):
pass
raise TypeError("Incompatible classes %s, %s" % (A.__class__, B.__class__))
|
2fc5c0585d8efdc1fb09f4b325b2b0c6737c2b330f407735515fb766e8ef5b87
|
from __future__ import print_function, division
from mpmath.libmp.libmpf import prec_to_dps
from sympy.core.add import Add
from sympy.core.basic import Basic
from sympy.core.expr import Expr
from sympy.core.function import expand_mul
from sympy.core.power import Pow
from sympy.core.symbol import (Symbol, Dummy, symbols,
_uniquely_named_symbol)
from sympy.core.numbers import Integer, mod_inverse, Float
from sympy.core.singleton import S
from sympy.core.sympify import sympify
from sympy.functions.elementary.miscellaneous import sqrt, Max, Min
from sympy.functions import exp, factorial
from sympy.polys import PurePoly, roots, cancel
from sympy.printing import sstr
from sympy.simplify import simplify as _simplify, nsimplify
from sympy.core.compatibility import reduce, as_int, string_types, Callable
from sympy.utilities.iterables import flatten, numbered_symbols
from sympy.core.compatibility import (is_sequence, default_sort_key, range,
NotIterable)
from sympy.utilities.exceptions import SymPyDeprecationWarning
from types import FunctionType
from .common import (a2idx, MatrixError, ShapeError,
NonSquareMatrixError, MatrixCommon)
from sympy.core.decorators import deprecated
def _iszero(x):
"""Returns True if x is zero."""
try:
return x.is_zero
except AttributeError:
return None
def _is_zero_after_expand_mul(x):
"""Tests by expand_mul only, suitable for polynomials and rational
functions."""
return expand_mul(x) == 0
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."""
def _eval_berkowitz_toeplitz_matrix(self):
"""Return (A,T) where T the Toeplitz matrix used in the Berkowitz algorithm
corresponding to `self` and A is the first principal submatrix."""
# the 0 x 0 case is trivial
if self.rows == 0 and self.cols == 0:
return self._new(1,1, [S.One])
#
# Partition self = [ a_11 R ]
# [ C A ]
#
a, R = self[0,0], self[0, 1:]
C, A = self[1:, 0], self[1:,1:]
#
# The Toeplitz matrix looks like
#
# [ 1 ]
# [ -a 1 ]
# [ -RC -a 1 ]
# [ -RAC -RC -a 1 ]
# [ -RA**2C -RAC -RC -a 1 ]
# etc.
# Compute the diagonal entries.
# Because multiplying matrix times vector is so much
# more efficient than matrix times matrix, recursively
# compute -R * A**n * C.
diags = [C]
for i in range(self.rows - 2):
diags.append(A * diags[i])
diags = [(-R*d)[0, 0] for d in diags]
diags = [S.One, -a] + diags
def entry(i,j):
if j > i:
return S.Zero
return diags[i - j]
toeplitz = self._new(self.cols + 1, self.rows, entry)
return (A, toeplitz)
def _eval_berkowitz_vector(self):
""" Run the Berkowitz algorithm and return a vector whose entries
are the coefficients of the characteristic polynomial of `self`.
Given N x N matrix, efficiently compute
coefficients of characteristic polynomials of 'self'
without division in the ground domain.
This method is particularly useful for computing determinant,
principal minors and characteristic polynomial when 'self'
has complicated coefficients e.g. polynomials. Semi-direct
usage of this algorithm is also important in computing
efficiently sub-resultant PRS.
Assuming that M is a square matrix of dimension N x N and
I is N x N identity matrix, then the Berkowitz vector is
an N x 1 vector whose entries are coefficients of the
polynomial
charpoly(M) = det(t*I - M)
As a consequence, all polynomials generated by Berkowitz
algorithm are monic.
For more information on the implemented algorithm refer to:
[1] S.J. Berkowitz, On computing the determinant in small
parallel time using a small number of processors, ACM,
Information Processing Letters 18, 1984, pp. 147-150
[2] M. Keber, Division-Free computation of sub-resultants
using Bezout matrices, Tech. Report MPI-I-2006-1-006,
Saarbrucken, 2006
"""
# handle the trivial cases
if self.rows == 0 and self.cols == 0:
return self._new(1, 1, [S.One])
elif self.rows == 1 and self.cols == 1:
return self._new(2, 1, [S.One, -self[0,0]])
submat, toeplitz = self._eval_berkowitz_toeplitz_matrix()
return toeplitz * submat._eval_berkowitz_vector()
def _eval_det_bareiss(self, iszerofunc=_is_zero_after_expand_mul):
"""Compute matrix determinant using Bareiss' fraction-free
algorithm which is an extension of the well known Gaussian
elimination method. This approach is best suited for dense
symbolic matrices and will result in a determinant with
minimal number of fractions. It means that less term
rewriting is needed on resulting formulae.
TODO: Implement algorithm for sparse matrices (SFF),
http://www.eecis.udel.edu/~saunders/papers/sffge/it5.ps.
"""
# Recursively implemented Bareiss' algorithm as per Deanna Richelle Leggett's
# thesis http://www.math.usm.edu/perry/Research/Thesis_DRL.pdf
def bareiss(mat, cumm=1):
if mat.rows == 0:
return S.One
elif mat.rows == 1:
return mat[0, 0]
# find a pivot and extract the remaining matrix
# With the default iszerofunc, _find_reasonable_pivot slows down
# the computation by the factor of 2.5 in one test.
# Relevant issues: #10279 and #13877.
pivot_pos, pivot_val, _, _ = _find_reasonable_pivot(mat[:, 0],
iszerofunc=iszerofunc)
if pivot_pos == None:
return S.Zero
# if we have a valid pivot, we'll do a "row swap", so keep the
# sign of the det
sign = (-1) ** (pivot_pos % 2)
# we want every row but the pivot row and every column
rows = list(i for i in range(mat.rows) if i != pivot_pos)
cols = list(range(mat.cols))
tmp_mat = mat.extract(rows, cols)
def entry(i, j):
ret = (pivot_val*tmp_mat[i, j + 1] - mat[pivot_pos, j + 1]*tmp_mat[i, 0]) / cumm
if not ret.is_Atom:
return cancel(ret)
return ret
return sign*bareiss(self._new(mat.rows - 1, mat.cols - 1, entry), pivot_val)
return cancel(bareiss(self))
def _eval_det_berkowitz(self):
""" Use the Berkowitz algorithm to compute the determinant."""
berk_vector = self._eval_berkowitz_vector()
return (-1)**(len(berk_vector) - 1) * berk_vector[-1]
def _eval_det_lu(self, iszerofunc=_iszero, simpfunc=None):
""" Computes the determinant of a matrix from its LU decomposition.
This function uses the LU decomposition computed by
LUDecomposition_Simple().
The keyword arguments iszerofunc and simpfunc are passed to
LUDecomposition_Simple().
iszerofunc is a callable that returns a boolean indicating if its
input is zero, or None if it cannot make the determination.
simpfunc is a callable that simplifies its input.
The default is simpfunc=None, which indicate that the pivot search
algorithm should not attempt to simplify any candidate pivots.
If simpfunc fails to simplify its input, then it must return its input
instead of a copy."""
if self.rows == 0:
return S.One
# sympy/matrices/tests/test_matrices.py contains a test that
# suggests that the determinant of a 0 x 0 matrix is one, by
# convention.
lu, row_swaps = self.LUdecomposition_Simple(iszerofunc=iszerofunc, simpfunc=None)
# P*A = L*U => det(A) = det(L)*det(U)/det(P) = det(P)*det(U).
# Lower triangular factor L encoded in lu has unit diagonal => det(L) = 1.
# P is a permutation matrix => det(P) in {-1, 1} => 1/det(P) = det(P).
# LUdecomposition_Simple() returns a list of row exchange index pairs, rather
# than a permutation matrix, but det(P) = (-1)**len(row_swaps).
# Avoid forming the potentially time consuming product of U's diagonal entries
# if the product is zero.
# Bottom right entry of U is 0 => det(A) = 0.
# It may be impossible to determine if this entry of U is zero when it is symbolic.
if iszerofunc(lu[lu.rows-1, lu.rows-1]):
return S.Zero
# Compute det(P)
det = -S.One if len(row_swaps)%2 else S.One
# Compute det(U) by calculating the product of U's diagonal entries.
# The upper triangular portion of lu is the upper triangular portion of the
# U factor in the LU decomposition.
for k in range(lu.rows):
det *= lu[k, k]
# return det(P)*det(U)
return det
def _eval_determinant(self):
"""Assumed to exist by matrix expressions; If we subclass
MatrixDeterminant, we can fully evaluate determinants."""
return self.det()
def adjugate(self, method="berkowitz"):
"""Returns the adjugate, or classical adjoint, of
a matrix. That is, the transpose of the matrix of cofactors.
https://en.wikipedia.org/wiki/Adjugate
See Also
========
cofactor_matrix
transpose
"""
return self.cofactor_matrix(method).transpose()
def charpoly(self, x='lambda', simplify=_simplify):
"""Computes characteristic polynomial det(x*I - self) where I is
the identity matrix.
A PurePoly is returned, so using different variables for ``x`` does
not affect the comparison or the polynomials:
Examples
========
>>> from sympy import Matrix
>>> from sympy.abc import x, y
>>> A = Matrix([[1, 3], [2, 0]])
>>> A.charpoly(x) == A.charpoly(y)
True
Specifying ``x`` is optional; a symbol named ``lambda`` is used by
default (which looks good when pretty-printed in unicode):
>>> A.charpoly().as_expr()
lambda**2 - lambda - 6
And if ``x`` clashes with an existing symbol, underscores will
be preppended to the name to make it unique:
>>> A = Matrix([[1, 2], [x, 0]])
>>> A.charpoly(x).as_expr()
_x**2 - _x - 2*x
Whether you pass a symbol or not, the generator can be obtained
with the gen attribute since it may not be the same as the symbol
that was passed:
>>> A.charpoly(x).gen
_x
>>> A.charpoly(x).gen == x
False
Notes
=====
The Samuelson-Berkowitz algorithm is used to compute
the characteristic polynomial efficiently and without any
division operations. Thus the characteristic polynomial over any
commutative ring without zero divisors can be computed.
See Also
========
det
"""
if self.rows != self.cols:
raise NonSquareMatrixError()
berk_vector = self._eval_berkowitz_vector()
x = _uniquely_named_symbol(x, berk_vector)
return PurePoly([simplify(a) for a in berk_vector], x)
def cofactor(self, i, j, method="berkowitz"):
"""Calculate the cofactor of an element.
See Also
========
cofactor_matrix
minor
minor_submatrix
"""
if self.rows != self.cols or self.rows < 1:
raise NonSquareMatrixError()
return (-1)**((i + j) % 2) * self.minor(i, j, method)
def cofactor_matrix(self, method="berkowitz"):
"""Return a matrix containing the cofactor of each element.
See Also
========
cofactor
minor
minor_submatrix
adjugate
"""
if self.rows != self.cols or self.rows < 1:
raise NonSquareMatrixError()
return self._new(self.rows, self.cols,
lambda i, j: self.cofactor(i, j, method))
def det(self, method="bareiss", iszerofunc=None):
"""Computes the determinant of a matrix.
Parameters
==========
method : string, optional
Specifies the algorithm used for computing the matrix determinant.
If the matrix is at most 3x3, a hard-coded formula is used and the
specified method is ignored. Otherwise, it defaults to
``'bareiss'``.
If it is set to ``'bareiss'``, Bareiss' fraction-free algorithm will
be used.
If it is set to ``'berkowitz'``, Berkowitz' algorithm will be used.
Otherwise, if it is set to ``'lu'``, LU decomposition will be used.
.. note::
For backward compatibility, legacy keys like "bareis" and
"det_lu" can still be used to indicate the corresponding
methods.
And the keys are also case-insensitive for now. However, it is
suggested to use the precise keys for specifying the method.
iszerofunc : FunctionType or None, optional
If it is set to ``None``, it will be defaulted to ``_iszero`` if the
method is set to ``'bareiss'``, and ``_is_zero_after_expand_mul`` if
the method is set to ``'lu'``.
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
tested as non-zero, and also ``None`` if it is undecidable.
Returns
=======
det : Basic
Result of determinant.
Raises
======
ValueError
If unrecognized keys are given for ``method`` or ``iszerofunc``.
NonSquareMatrixError
If attempted to calculate determinant from a non-square matrix.
"""
# sanitize `method`
method = method.lower()
if method == "bareis":
method = "bareiss"
if method == "det_lu":
method = "lu"
if method not in ("bareiss", "berkowitz", "lu"):
raise ValueError("Determinant method '%s' unrecognized" % method)
if iszerofunc is None:
if method == "bareiss":
iszerofunc = _is_zero_after_expand_mul
elif method == "lu":
iszerofunc = _iszero
elif not isinstance(iszerofunc, FunctionType):
raise ValueError("Zero testing method '%s' unrecognized" % iszerofunc)
# if methods were made internal and all determinant calculations
# passed through here, then these lines could be factored out of
# the method routines
if self.rows != self.cols:
raise NonSquareMatrixError()
n = self.rows
if n == 0:
return S.One
elif n == 1:
return self[0,0]
elif n == 2:
return self[0, 0] * self[1, 1] - self[0, 1] * self[1, 0]
elif n == 3:
return (self[0, 0] * self[1, 1] * self[2, 2]
+ self[0, 1] * self[1, 2] * self[2, 0]
+ self[0, 2] * self[1, 0] * self[2, 1]
- self[0, 2] * self[1, 1] * self[2, 0]
- self[0, 0] * self[1, 2] * self[2, 1]
- self[0, 1] * self[1, 0] * self[2, 2])
if method == "bareiss":
return self._eval_det_bareiss(iszerofunc=iszerofunc)
elif method == "berkowitz":
return self._eval_det_berkowitz()
elif method == "lu":
return self._eval_det_lu(iszerofunc=iszerofunc)
def minor(self, i, j, method="berkowitz"):
"""Return the (i,j) minor of `self`. That is,
return the determinant of the matrix obtained by deleting
the `i`th row and `j`th column from `self`.
See Also
========
minor_submatrix
cofactor
det
"""
if self.rows != self.cols or self.rows < 1:
raise NonSquareMatrixError()
return self.minor_submatrix(i, j).det(method=method)
def minor_submatrix(self, i, j):
"""Return the submatrix obtained by removing the `i`th row
and `j`th column from `self`.
See Also
========
minor
cofactor
"""
if i < 0:
i += self.rows
if j < 0:
j += self.cols
if not 0 <= i < self.rows or not 0 <= j < self.cols:
raise ValueError("`i` and `j` must satisfy 0 <= i < `self.rows` "
"(%d)" % self.rows + "and 0 <= j < `self.cols` (%d)." % self.cols)
rows = [a for a in range(self.rows) if a != i]
cols = [a for a in range(self.cols) if a != j]
return self.extract(rows, cols)
class MatrixReductions(MatrixDeterminant):
"""Provides basic matrix row/column operations.
Should not be instantiated directly."""
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_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_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 _eval_echelon_form(self, iszerofunc, simpfunc):
"""Returns (mat, swaps) where `mat` is a row-equivalent matrix
in echelon form and `swaps` is a list of row-swaps performed."""
reduced, pivot_cols, swaps = self._row_reduce(iszerofunc, simpfunc,
normalize_last=True,
normalize=False,
zero_above=False)
return reduced, pivot_cols, swaps
def _eval_is_echelon(self, iszerofunc):
if self.rows <= 0 or self.cols <= 0:
return True
zeros_below = all(iszerofunc(t) for t in self[1:, 0])
if iszerofunc(self[0, 0]):
return zeros_below and self[:, 1:]._eval_is_echelon(iszerofunc)
return zeros_below and self[1:, 1:]._eval_is_echelon(iszerofunc)
def _eval_rref(self, iszerofunc, simpfunc, normalize_last=True):
reduced, pivot_cols, swaps = self._row_reduce(iszerofunc, simpfunc,
normalize_last, normalize=True,
zero_above=True)
return reduced, pivot_cols
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))
# 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))
if 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 = set((col, k, col1, col2)).difference([None])
if len(cols) > 2:
# maybe the user left `k` by mistake?
cols = set((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))
if 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))
return op, col, k, col1, col2
def _permute_complexity_right(self, iszerofunc):
"""Permute columns with complicated elements as
far right as they can go. Since the `sympy` row reduction
algorithms start on the left, having complexity right-shifted
speeds things up.
Returns a tuple (mat, perm) where perm is a permutation
of the columns to perform to shift the complex columns right, and mat
is the permuted matrix."""
def complexity(i):
# the complexity of a column will be judged by how many
# element's zero-ness cannot be determined
return sum(1 if iszerofunc(e) is None else 0 for e in self[:, i])
complex = [(complexity(i), i) for i in range(self.cols)]
perm = [j for (i, j) in sorted(complex)]
return (self.permute(perm, orientation='cols'), perm)
def _row_reduce(self, iszerofunc, simpfunc, normalize_last=True,
normalize=True, zero_above=True):
"""Row reduce `self` and return a tuple (rref_matrix,
pivot_cols, swaps) where pivot_cols are the pivot columns
and swaps are any row swaps that were used in the process
of row reduction.
Parameters
==========
iszerofunc : determines if an entry can be used as a pivot
simpfunc : used to simplify elements and test if they are
zero if `iszerofunc` returns `None`
normalize_last : indicates where all row reduction should
happen in a fraction-free manner and then the rows are
normalized (so that the pivots are 1), or whether
rows should be normalized along the way (like the naive
row reduction algorithm)
normalize : whether pivot rows should be normalized so that
the pivot value is 1
zero_above : whether entries above the pivot should be zeroed.
If `zero_above=False`, an echelon matrix will be returned.
"""
rows, cols = self.rows, self.cols
mat = list(self)
def get_col(i):
return mat[i::cols]
def row_swap(i, j):
mat[i*cols:(i + 1)*cols], mat[j*cols:(j + 1)*cols] = \
mat[j*cols:(j + 1)*cols], mat[i*cols:(i + 1)*cols]
def cross_cancel(a, i, b, j):
"""Does the row op row[i] = a*row[i] - b*row[j]"""
q = (j - i)*cols
for p in range(i*cols, (i + 1)*cols):
mat[p] = a*mat[p] - b*mat[p + q]
piv_row, piv_col = 0, 0
pivot_cols = []
swaps = []
# use a fraction free method to zero above and below each pivot
while piv_col < cols and piv_row < rows:
pivot_offset, pivot_val, \
assumed_nonzero, newly_determined = _find_reasonable_pivot(
get_col(piv_col)[piv_row:], iszerofunc, simpfunc)
# _find_reasonable_pivot may have simplified some things
# in the process. Let's not let them go to waste
for (offset, val) in newly_determined:
offset += piv_row
mat[offset*cols + piv_col] = val
if pivot_offset is None:
piv_col += 1
continue
pivot_cols.append(piv_col)
if pivot_offset != 0:
row_swap(piv_row, pivot_offset + piv_row)
swaps.append((piv_row, pivot_offset + piv_row))
# if we aren't normalizing last, we normalize
# before we zero the other rows
if normalize_last is False:
i, j = piv_row, piv_col
mat[i*cols + j] = S.One
for p in range(i*cols + j + 1, (i + 1)*cols):
mat[p] = mat[p] / pivot_val
# after normalizing, the pivot value is 1
pivot_val = S.One
# zero above and below the pivot
for row in range(rows):
# don't zero our current row
if row == piv_row:
continue
# don't zero above the pivot unless we're told.
if zero_above is False and row < piv_row:
continue
# if we're already a zero, don't do anything
val = mat[row*cols + piv_col]
if iszerofunc(val):
continue
cross_cancel(pivot_val, row, val, piv_row)
piv_row += 1
# normalize each row
if normalize_last is True and normalize is True:
for piv_i, piv_j in enumerate(pivot_cols):
pivot_val = mat[piv_i*cols + piv_j]
mat[piv_i*cols + piv_j] = S.One
for p in range(piv_i*cols + piv_j + 1, (piv_i + 1)*cols):
mat[p] = mat[p] / pivot_val
return self._new(self.rows, self.cols, mat), tuple(pivot_cols), tuple(swaps)
def echelon_form(self, iszerofunc=_iszero, simplify=False, with_pivots=False):
"""Returns a matrix row-equivalent to `self` that is
in echelon form. Note that echelon form of a matrix
is *not* unique, however, properties like the row
space and the null space are preserved."""
simpfunc = simplify if isinstance(
simplify, FunctionType) else _simplify
mat, pivots, swaps = self._eval_echelon_form(iszerofunc, simpfunc)
if with_pivots:
return mat, pivots
return mat
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)
@property
def is_echelon(self, iszerofunc=_iszero):
"""Returns `True` if the matrix is in echelon form.
That is, all rows of zeros are at the bottom, and below
each leading non-zero in a row are exclusively zeros."""
return self._eval_is_echelon(iszerofunc)
def rank(self, iszerofunc=_iszero, simplify=False):
"""
Returns the rank of a matrix
>>> from sympy import Matrix
>>> from sympy.abc import x
>>> m = Matrix([[1, 2], [x, 1 - 1/x]])
>>> m.rank()
2
>>> n = Matrix(3, 3, range(1, 10))
>>> n.rank()
2
"""
simpfunc = simplify if isinstance(
simplify, FunctionType) else _simplify
# for small matrices, we compute the rank explicitly
# if is_zero on elements doesn't answer the question
# for small matrices, we fall back to the full routine.
if self.rows <= 0 or self.cols <= 0:
return 0
if self.rows <= 1 or self.cols <= 1:
zeros = [iszerofunc(x) for x in self]
if False in zeros:
return 1
if self.rows == 2 and self.cols == 2:
zeros = [iszerofunc(x) for x in self]
if not False in zeros and not None in zeros:
return 0
det = self.det()
if iszerofunc(det) and False in zeros:
return 1
if iszerofunc(det) is False:
return 2
mat, _ = self._permute_complexity_right(iszerofunc=iszerofunc)
echelon_form, pivots, swaps = mat._eval_echelon_form(iszerofunc=iszerofunc, simpfunc=simpfunc)
return len(pivots)
def rref(self, iszerofunc=_iszero, simplify=False, pivots=True, normalize_last=True):
"""Return reduced row-echelon form of matrix and indices of pivot vars.
Parameters
==========
iszerofunc : Function
A function used for detecting whether an element can
act as a pivot. ``lambda x: x.is_zero`` is used by default.
simplify : Function
A function used to simplify elements when looking for a pivot.
By default SymPy's ``simplify`` is used.
pivots : True or False
If ``True``, a tuple containing the row-reduced matrix and a tuple
of pivot columns is returned. If ``False`` just the row-reduced
matrix is returned.
normalize_last : True or False
If ``True``, no pivots are normalized to `1` until after all
entries above and below each pivot are zeroed. This means the row
reduction algorithm is fraction free until the very last step.
If ``False``, the naive row reduction procedure is used where
each pivot is normalized to be `1` before row operations are
used to zero above and below the pivot.
Notes
=====
The default value of ``normalize_last=True`` can provide significant
speedup to row reduction, especially on matrices with symbols. However,
if you depend on the form row reduction algorithm leaves entries
of the matrix, set ``noramlize_last=False``
Examples
========
>>> from sympy import Matrix
>>> from sympy.abc import x
>>> m = Matrix([[1, 2], [x, 1 - 1/x]])
>>> m.rref()
(Matrix([
[1, 0],
[0, 1]]), (0, 1))
>>> rref_matrix, rref_pivots = m.rref()
>>> rref_matrix
Matrix([
[1, 0],
[0, 1]])
>>> rref_pivots
(0, 1)
"""
simpfunc = simplify if isinstance(
simplify, FunctionType) else _simplify
ret, pivot_cols = self._eval_rref(iszerofunc=iszerofunc,
simpfunc=simpfunc,
normalize_last=normalize_last)
if pivots:
ret = (ret, pivot_cols)
return ret
class MatrixSubspaces(MatrixReductions):
"""Provides methods relating to the fundamental subspaces
of a matrix. Should not be instantiated directly."""
def columnspace(self, simplify=False):
"""Returns a list of vectors (Matrix objects) that span columnspace of self
Examples
========
>>> from sympy.matrices import Matrix
>>> m = Matrix(3, 3, [1, 3, 0, -2, -6, 0, 3, 9, 6])
>>> m
Matrix([
[ 1, 3, 0],
[-2, -6, 0],
[ 3, 9, 6]])
>>> m.columnspace()
[Matrix([
[ 1],
[-2],
[ 3]]), Matrix([
[0],
[0],
[6]])]
See Also
========
nullspace
rowspace
"""
reduced, pivots = self.echelon_form(simplify=simplify, with_pivots=True)
return [self.col(i) for i in pivots]
def nullspace(self, simplify=False, iszerofunc=_iszero):
"""Returns list of vectors (Matrix objects) that span nullspace of self
Examples
========
>>> from sympy.matrices import Matrix
>>> m = Matrix(3, 3, [1, 3, 0, -2, -6, 0, 3, 9, 6])
>>> m
Matrix([
[ 1, 3, 0],
[-2, -6, 0],
[ 3, 9, 6]])
>>> m.nullspace()
[Matrix([
[-3],
[ 1],
[ 0]])]
See Also
========
columnspace
rowspace
"""
reduced, pivots = self.rref(iszerofunc=iszerofunc, simplify=simplify)
free_vars = [i for i in range(self.cols) if i not in pivots]
basis = []
for free_var in free_vars:
# for each free variable, we will set it to 1 and all others
# to 0. Then, we will use back substitution to solve the system
vec = [S.Zero]*self.cols
vec[free_var] = S.One
for piv_row, piv_col in enumerate(pivots):
vec[piv_col] -= reduced[piv_row, free_var]
basis.append(vec)
return [self._new(self.cols, 1, b) for b in basis]
def rowspace(self, simplify=False):
"""Returns a list of vectors that span the row space of self."""
reduced, pivots = self.echelon_form(simplify=simplify, with_pivots=True)
return [reduced.row(i) for i in range(len(pivots))]
@classmethod
def orthogonalize(cls, *vecs, **kwargs):
"""Apply the Gram-Schmidt orthogonalization procedure
to vectors supplied in `vecs`.
Parameters
==========
vecs
vectors to be made orthogonal
normalize : bool
If true, return an orthonormal basis.
"""
normalize = kwargs.get('normalize', False)
def project(a, b):
return b * (a.dot(b) / b.dot(b))
def perp_to_subspace(vec, basis):
"""projects vec onto the subspace given
by the orthogonal basis `basis`"""
components = [project(vec, b) for b in basis]
if len(basis) == 0:
return vec
return vec - reduce(lambda a, b: a + b, components)
ret = []
# make sure we start with a non-zero vector
while len(vecs) > 0 and vecs[0].is_zero:
del vecs[0]
for vec in vecs:
perp = perp_to_subspace(vec, ret)
if not perp.is_zero:
ret.append(perp)
if normalize:
ret = [vec / vec.norm() for vec in ret]
return ret
class MatrixEigen(MatrixSubspaces):
"""Provides basic matrix eigenvalue/vector operations.
Should not be instantiated directly."""
_cache_is_diagonalizable = None
_cache_eigenvects = None
def diagonalize(self, 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 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 self.is_square:
raise NonSquareMatrixError()
if not self.is_diagonalizable(reals_only=reals_only, clear_cache=False):
raise MatrixError("Matrix is not diagonalizable")
eigenvecs = self._cache_eigenvects
if eigenvecs is None:
eigenvecs = self.eigenvects(simplify=True)
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 self.hstack(*p_cols), self.diag(*diag)
def eigenvals(self, error_when_incomplete=True, **flags):
r"""Return eigenvalues using the Berkowitz agorithm to compute
the characteristic polynomial.
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.
See Also
========
MatrixDeterminant.charpoly
eigenvects
Notes
=====
Eigenvalues of a matrix `A` can be computed by solving a matrix
equation `\det(A - \lambda I) = 0`
"""
simplify = flags.get('simplify', False) # Collect simplify flag before popped up, to reuse later in the routine.
multiple = flags.get('multiple', False) # Collect multiple flag to decide whether return as a dict or list.
mat = self
if not mat:
return {}
if flags.pop('rational', True):
if any(v.has(Float) for v in mat):
mat = mat.applyfunc(lambda x: nsimplify(x, rational=True))
if mat.is_upper or mat.is_lower:
if not self.is_square:
raise NonSquareMatrixError()
diagonal_entries = [mat[i, i] for i in range(mat.rows)]
if multiple:
eigs = diagonal_entries
else:
eigs = {}
for diagonal_entry in diagonal_entries:
if diagonal_entry not in eigs:
eigs[diagonal_entry] = 0
eigs[diagonal_entry] += 1
else:
flags.pop('simplify', None) # pop unsupported flag
if isinstance(simplify, FunctionType):
eigs = roots(mat.charpoly(x=Dummy('x'), simplify=simplify), **flags)
else:
eigs = roots(mat.charpoly(x=Dummy('x')), **flags)
# make sure the algebraic multiplicty sums to the
# size of the matrix
if error_when_incomplete and (sum(eigs.values()) if
isinstance(eigs, dict) else len(eigs)) != self.cols:
raise MatrixError("Could not compute eigenvalues for {}".format(self))
# Since 'simplify' flag is unsupported in roots()
# simplify() function will be applied once at the end of the routine.
if not simplify:
return eigs
if not isinstance(simplify, FunctionType):
simplify = _simplify
# With 'multiple' flag set true, simplify() will be mapped for the list
# Otherwise, simplify() will be mapped for the keys of the dictionary
if not multiple:
return {simplify(key): value for key, value in eigs.items()}
else:
return [simplify(value) for value in eigs]
def eigenvects(self, error_when_incomplete=True, iszerofunc=_iszero, **flags):
"""Return list of triples (eigenval, multiplicity, eigenspace).
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.
See Also
========
eigenvals
MatrixSubspaces.nullspace
"""
from sympy.matrices import eye
simplify = flags.get('simplify', True)
if not isinstance(simplify, FunctionType):
simpfunc = _simplify if simplify else lambda x: x
primitive = flags.get('simplify', False)
chop = flags.pop('chop', False)
flags.pop('multiple', None) # remove this if it's there
mat = self
# roots doesn't like Floats, so replace them with Rationals
has_floats = any(v.has(Float) for v in self)
if has_floats:
mat = mat.applyfunc(lambda x: nsimplify(x, rational=True))
def eigenspace(eigenval):
"""Get a basis for the eigenspace for a particular eigenvalue"""
m = mat - self.eye(mat.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 %s" % eigenval)
return ret
eigenvals = mat.eigenvals(rational=False,
error_when_incomplete=error_when_incomplete,
**flags)
ret = [(val, mult, eigenspace(val)) for val, mult in
sorted(eigenvals.items(), key=default_sort_key)]
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(self, reals_only=False, **kwargs):
"""Returns true if a matrix is diagonalizable.
Parameters
==========
reals_only : bool. If reals_only=True, determine whether the matrix can be
diagonalized without complex numbers. (Default: False)
kwargs
======
clear_cache : bool. If True, clear the result of any computations when finished.
(Default: True)
Examples
========
>>> from sympy 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]])
>>> m.is_diagonalizable()
True
>>> m = Matrix(2, 2, [0, 1, 0, 0])
>>> m
Matrix([
[0, 1],
[0, 0]])
>>> m.is_diagonalizable()
False
>>> m = Matrix(2, 2, [0, 1, -1, 0])
>>> m
Matrix([
[ 0, 1],
[-1, 0]])
>>> m.is_diagonalizable()
True
>>> m.is_diagonalizable(reals_only=True)
False
See Also
========
is_diagonal
diagonalize
"""
clear_cache = kwargs.get('clear_cache', True)
if 'clear_subproducts' in kwargs:
clear_cache = kwargs.get('clear_subproducts')
def cleanup():
"""Clears any cached values if requested"""
if clear_cache:
self._cache_eigenvects = None
self._cache_is_diagonalizable = None
if not self.is_square:
cleanup()
return False
# use the cached value if we have it
if self._cache_is_diagonalizable is not None:
ret = self._cache_is_diagonalizable
cleanup()
return ret
if all(e.is_real for e in self) and self.is_symmetric():
# every real symmetric matrix is real diagonalizable
self._cache_is_diagonalizable = True
cleanup()
return True
self._cache_eigenvects = self.eigenvects(simplify=True)
ret = True
for val, mult, basis in self._cache_eigenvects:
# if we have a complex eigenvalue
if reals_only and not val.is_real:
ret = False
# if the geometric multiplicity doesn't equal the algebraic
if mult != len(basis):
ret = False
cleanup()
return ret
def jordan_form(self, calc_transform=True, **kwargs):
"""Return `(P, J)` where `J` is a Jordan block
matrix and `P` is a matrix such that
`self == P*J*P**-1`
Parameters
==========
calc_transform : bool
If ``False``, then only `J` is returned.
chop : bool
All matrices are convered 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 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 self.is_square:
raise NonSquareMatrixError("Only square matrices have Jordan forms")
chop = kwargs.pop('chop', False)
mat = self
has_floats = any(v.has(Float) for v in self)
if has_floats:
try:
max_prec = max(term._prec for term in self._mat 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(prec=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 (self - 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)] * mat_cache[(val, 1)]
else:
mat_cache[(val, pow)] = (mat - val*self.eye(self.rows))**pow
return mat_cache[(val, pow)]
# helper functions
def nullity_chain(val):
"""Calculate the sequence [0, nullity(E), nullity(E**2), ...]
until it is constant where `E = self - val*I`"""
# mat.rank() is faster than computing the null space,
# so use the rank-nullity theorem
cols = self.cols
ret = [0]
nullity = cols - eig_mat(val, 1).rank()
i = 2
while nullity != ret[-1]:
ret.append(nullity)
nullity = cols - eig_mat(val, i).rank()
i += 1
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 = self.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 found all the roots by counting
# the algebraic multiplicity
if sum(m for m in eigs.values()) != mat.cols:
raise MatrixError("Could not compute eigenvalues for {}".format(mat))
# 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):
chain = nullity_chain(eig)
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))
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))*vec 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(self, **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 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 = self.transpose().eigenvects(**flags)
return [(val, mult, [l.transpose() for l in basis]) for val, mult, basis in eigs]
def singular_values(self):
"""Compute the singular values of a Matrix
Examples
========
>>> from sympy import Matrix, Symbol
>>> x = Symbol('x', real=True)
>>> A = Matrix([[0, 1, 0], [0, x, 0], [-1, 0, 0]])
>>> A.singular_values()
[sqrt(x**2 + 1), 1, 0]
See Also
========
condition_number
"""
mat = self
# Compute eigenvalues of A.H A
valmultpairs = (mat.H * mat).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!
# sort them in descending order
vals.sort(reverse=True, key=default_sort_key)
return vals
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 import Derivative
kwargs.setdefault('evaluate', True)
deriv = Derivative(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 _accept_eval_derivative(self, s):
return s._visit_eval_derivative_array(self)
def _visit_eval_derivative_scalar(self, base):
# Types are (base: scalar, self: matrix)
return self.applyfunc(lambda x: base.diff(x))
def _visit_eval_derivative_array(self, base):
# Types are (base: array/matrix, self: matrix)
from sympy import derive_by_array
return derive_by_array(base, self)
def integrate(self, *args):
"""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))
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 = S.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 = [S.One, a] + items
for i in range(n):
T[i:, i] = items[:n - i + 1]
transforms[k - 1] = T
polys = [self._new([S.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 self.det(method='bareiss')
def det_bareiss(self):
"""Compute matrix determinant using Bareiss' fraction-free
algorithm which is an extension of the well known Gaussian
elimination method. This approach is best suited for dense
symbolic matrices and will result in a determinant with
minimal number of fractions. It means that less term
rewriting is needed on resulting formulae.
TODO: Implement algorithm for sparse matrices (SFF),
http://www.eecis.udel.edu/~saunders/papers/sffge/it5.ps.
See Also
========
det
berkowitz_det
"""
return self.det(method='bareiss')
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')
class MatrixBase(MatrixDeprecated,
MatrixCalculus,
MatrixEigen,
MatrixCommon):
"""Base class for matrix objects."""
# Added just for numpy compatibility
__array_priority__ = 11
is_Matrix = True
_class_priority = 3
_sympify = staticmethod(sympify)
__hash__ = None # Mutable
# Defined here the same as on Basic.
# We don't define _repr_png_ here because it would add a large amount of
# data to any notebook containing SymPy expressions, without adding
# anything useful to the notebook. It can still enabled manually, e.g.,
# for the qtconsole, with init_printing().
def _repr_latex_(self):
"""
IPython/Jupyter LaTeX printing
To change the behavior of this (e.g., pass in some settings to LaTeX),
use init_printing(). init_printing() will also enable LaTeX printing
for built in numeric types like ints and container types that contain
SymPy objects, like lists and dictionaries of expressions.
"""
from sympy.printing.latex import latex
s = latex(self, mode='plain')
return "$\\displaystyle %s$" % s
_repr_latex_orig = _repr_latex_
def __array__(self, dtype=object):
from .dense import matrix2numpy
return matrix2numpy(self, dtype=dtype)
def __getattr__(self, attr):
if attr in ('diff', 'integrate', 'limit'):
def doit(*args):
item_doit = lambda item: getattr(item, attr)(*args)
return self.applyfunc(item_doit)
return doit
else:
raise AttributeError(
"%s has no attribute %s." % (self.__class__.__name__, attr))
def __len__(self):
"""Return the number of elements of self.
Implemented mainly so bool(Matrix()) == False.
"""
return self.rows * self.cols
def __mathml__(self):
mml = ""
for i in range(self.rows):
mml += "<matrixrow>"
for j in range(self.cols):
mml += self[i, j].__mathml__()
mml += "</matrixrow>"
return "<matrix>" + mml + "</matrix>"
# needed for python 2 compatibility
def __ne__(self, other):
return not self == other
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 == 0 and (n < N - 1) != False:
raise ValueError("Matrix det == 0; not invertible")
elif l == 0 and N > 1 and n % 1 != 0:
raise ValueError("Non-integer power cannot be evaluated")
for i in range(N):
for j in range(N-i):
bn = binomial(n, i)
if isinstance(bn, binomial):
bn = bn._eval_expand_func()
jc[j, i+j] = l**(n-i)*bn
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*diag(*jordan_cells)*P.inv())
def __repr__(self):
return sstr(self)
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 _diagonalize_clear_subproducts(self):
del self._is_symbolic
del self._is_symmetric
del self._eigenvects
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 _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]])
"""
from sympy.matrices.sparse import SparseMatrix
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]._mat
# 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()._mat
# Matrix(numpy.ones((2, 2)))
elif hasattr(args[0], "__array__"):
# 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 = args[0].__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:
rows, cols = arr.shape[0], 1
flat_list = [S.Zero] * rows
for i in range(len(arr)):
flat_list[i] = cls._sympify(arr[i])
return rows, cols, flat_list
else:
raise NotImplementedError(
"SymPy supports just 1D and 2D matrices")
# Matrix([1, 2, 3]) or Matrix([[1, 2], [3, 4]])
elif is_sequence(args[0]) \
and not isinstance(args[0], DeferredVector):
in_mat = []
ncol = set()
for row in args[0]:
if isinstance(row, MatrixBase):
in_mat.extend(row.tolist())
if row.cols or row.rows: # only pay attention if it's not 0x0
ncol.add(row.cols)
else:
in_mat.append(row)
try:
ncol.add(len(row))
except TypeError:
ncol.add(1)
if len(ncol) > 1:
raise ValueError("Got rows of variable lengths: %s" %
sorted(list(ncol)))
cols = ncol.pop() if ncol else 0
rows = len(in_mat) if cols else 0
if rows:
if not is_sequence(in_mat[0]):
cols = 1
flat_list = [cls._sympify(i) for i in in_mat]
return rows, cols, flat_list
flat_list = []
for j in range(rows):
for i in range(cols):
flat_list.append(cls._sympify(in_mat[j][i]))
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("Data type not understood")
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 cholesky_solve(self, 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
========
lower_triangular_solve
upper_triangular_solve
gauss_jordan_solve
diagonal_solve
LDLsolve
LUsolve
QRsolve
pinv_solve
"""
hermitian = True
if self.is_symmetric():
hermitian = False
L = self._cholesky(hermitian=hermitian)
elif self.is_hermitian:
L = self._cholesky(hermitian=hermitian)
elif self.rows >= self.cols:
L = (self.H * self)._cholesky(hermitian=hermitian)
rhs = self.H * rhs
else:
raise NotImplementedError('Under-determined System. '
'Try M.gauss_jordan_solve(rhs)')
Y = L._lower_triangular_solve(rhs)
if hermitian:
return (L.H)._upper_triangular_solve(Y)
else:
return (L.T)._upper_triangular_solve(Y)
def cholesky(self, hermitian=True):
"""Returns the Cholesky-type decomposition L of a matrix A
such that L * L.H == A if hermitian flag is True,
or L * L.T == A if hermitian is False.
A must be a Hermitian positive-definite matrix if hermitian is True,
or a symmetric matrix if it is False.
Examples
========
>>> from sympy.matrices import Matrix
>>> A = Matrix(((25, 15, -5), (15, 18, 0), (-5, 0, 11)))
>>> A.cholesky()
Matrix([
[ 5, 0, 0],
[ 3, 3, 0],
[-1, 1, 3]])
>>> A.cholesky() * A.cholesky().T
Matrix([
[25, 15, -5],
[15, 18, 0],
[-5, 0, 11]])
The matrix can have complex entries:
>>> from sympy import I
>>> A = Matrix(((9, 3*I), (-3*I, 5)))
>>> A.cholesky()
Matrix([
[ 3, 0],
[-I, 2]])
>>> A.cholesky() * A.cholesky().H
Matrix([
[ 9, 3*I],
[-3*I, 5]])
Non-hermitian Cholesky-type decomposition may be useful when the
matrix is not positive-definite.
>>> A = Matrix([[1, 2], [2, 1]])
>>> L = A.cholesky(hermitian=False)
>>> L
Matrix([
[1, 0],
[2, sqrt(3)*I]])
>>> L*L.T == A
True
See Also
========
LDLdecomposition
LUdecomposition
QRdecomposition
"""
if not self.is_square:
raise NonSquareMatrixError("Matrix must be square.")
if hermitian and not self.is_hermitian:
raise ValueError("Matrix must be Hermitian.")
if not hermitian and not self.is_symmetric():
raise ValueError("Matrix must be symmetric.")
return self._cholesky(hermitian=hermitian)
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 S.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._mat)
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
"""
if not is_sequence(b):
raise TypeError(
"`b` must be an ordered iterable or Matrix, not %s." %
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
========
conjugate: By-element conjugation
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 diagonal_solve(self, 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
========
lower_triangular_solve
upper_triangular_solve
gauss_jordan_solve
cholesky_solve
LDLsolve
LUsolve
QRsolve
pinv_solve
"""
if not self.is_diagonal:
raise TypeError("Matrix should be diagonal")
if rhs.rows != self.rows:
raise TypeError("Size mis-match")
return self._diagonal_solve(rhs)
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 exp(self):
"""Return the exponentiation of a square matrix."""
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")
def _jblock_exponential(b):
# This function computes the matrix exponential for one single Jordan block
nr = b.rows
l = b[0, 0]
if nr == 1:
res = exp(l)
else:
from sympy import eye
# extract the diagonal part
d = b[0, 0] * eye(nr)
# and the nilpotent part
n = b - d
# compute its exponential
nex = eye(nr)
for i in range(1, nr):
nex = nex + n ** i / factorial(i)
# combine the two parts
res = exp(b[0, 0]) * nex
return (res)
blocks = list(map(_jblock_exponential, cells))
from sympy.matrices import diag
from sympy import re
eJ = diag(*blocks)
# n = self.rows
ret = P * eJ * P.inv()
if all(value.is_real for value in self.values()):
return type(self)(re(ret))
else:
return type(self)(ret)
def gauss_jordan_solve(self, 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 : List
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 index of the free variables
in the solutions (column Matrix) will be returned by freevar, if
the flag `freevar` is set to `True`.
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.
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]])
>>> 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, [])
See Also
========
lower_triangular_solve
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
aug = self.hstack(self.copy(), b.copy())
row, col = aug[:, :-1].shape
# solve by reduced row echelon form
A, pivots = aug.rref(simplify=True)
A, v = A[:, :-1], A[:, -1]
pivots = list(filter(lambda p: p < col, pivots))
rank = len(pivots)
# Bring to block form
permutation = Matrix(range(col)).T
A = A.vstack(A, permutation)
for i, c in enumerate(pivots):
A.col_swap(i, c)
A, permutation = A[:-1, :], A[-1, :]
# check for existence of solutions
# rank of aug Matrix should be equal to rank of coefficient matrix
if not v[rank:, 0].is_zero:
raise ValueError("Linear system has no solution")
# Get index of free symbols (free parameters)
free_var_index = permutation[
len(pivots):] # non-pivots columns are free variables
# Free parameters
# what are current unnumbered free symbol names?
name = _uniquely_named_symbol('tau', aug,
compare=lambda i: str(i).rstrip('1234567890')).name
gen = numbered_symbols(name)
tau = Matrix([next(gen) for k in range(col - rank)]).reshape(col - rank, 1)
# Full parametric solution
V = A[:rank, rank:]
vt = v[:rank, 0]
free_sol = tau.vstack(vt - V * tau, tau)
# Undo permutation
sol = zeros(col, 1)
for k, v in enumerate(free_sol):
sol[permutation[k], 0] = v
if freevar:
return sol, tau, free_var_index
else:
return sol, tau
def inv_mod(self, m):
r"""
Returns the inverse of the matrix `K` (mod `m`), if it exists.
Method to find the matrix inverse of `K` (mod `m`) implemented in this function:
* Compute `\mathrm{adj}(K) = \mathrm{cof}(K)^t`, the adjoint matrix of `K`.
* Compute `r = 1/\mathrm{det}(K) \pmod m`.
* `K^{-1} = r\cdot \mathrm{adj}(K) \pmod m`.
Examples
========
>>> from sympy import Matrix
>>> A = Matrix(2, 2, [1, 2, 3, 4])
>>> A.inv_mod(5)
Matrix([
[3, 1],
[4, 2]])
>>> A.inv_mod(3)
Matrix([
[1, 1],
[0, 1]])
"""
if not self.is_square:
raise NonSquareMatrixError()
N = self.cols
det_K = self.det()
det_inv = None
try:
det_inv = mod_inverse(det_K, m)
except ValueError:
raise ValueError('Matrix is not invertible (mod %d)' % m)
K_adj = self.adjugate()
K_inv = self.__class__(N, N,
[det_inv * K_adj[i, j] % m for i in range(N) for
j in range(N)])
return K_inv
def inverse_ADJ(self, iszerofunc=_iszero):
"""Calculates the inverse using the adjugate matrix and a determinant.
See Also
========
inv
inverse_LU
inverse_GE
"""
if not self.is_square:
raise NonSquareMatrixError("A Matrix must be square to invert.")
d = self.det(method='berkowitz')
zero = d.equals(0)
if zero is None:
# if equals() can't decide, will rref be able to?
ok = self.rref(simplify=True)[0]
zero = any(iszerofunc(ok[j, j]) for j in range(ok.rows))
if zero:
raise ValueError("Matrix det == 0; not invertible.")
return self.adjugate() / d
def inverse_GE(self, iszerofunc=_iszero):
"""Calculates the inverse using Gaussian elimination.
See Also
========
inv
inverse_LU
inverse_ADJ
"""
from .dense import Matrix
if not self.is_square:
raise NonSquareMatrixError("A Matrix must be square to invert.")
big = Matrix.hstack(self.as_mutable(), Matrix.eye(self.rows))
red = big.rref(iszerofunc=iszerofunc, simplify=True)[0]
if any(iszerofunc(red[j, j]) for j in range(red.rows)):
raise ValueError("Matrix det == 0; not invertible.")
return self._new(red[:, big.rows:])
def inverse_LU(self, iszerofunc=_iszero):
"""Calculates the inverse using LU decomposition.
See Also
========
inv
inverse_GE
inverse_ADJ
"""
if not self.is_square:
raise NonSquareMatrixError()
ok = self.rref(simplify=True)[0]
if any(iszerofunc(ok[j, j]) for j in range(ok.rows)):
raise ValueError("Matrix det == 0; not invertible.")
return self.LUsolve(self.eye(self.rows), iszerofunc=_iszero)
def inv(self, method=None, **kwargs):
"""
Return the inverse of a matrix.
CASE 1: If the matrix is a dense matrix.
Return the matrix inverse using the method indicated (default
is Gauss elimination).
Parameters
==========
method : ('GE', 'LU', or 'ADJ')
Notes
=====
According to the ``method`` keyword, it calls the appropriate method:
GE .... inverse_GE(); default
LU .... inverse_LU()
ADJ ... inverse_ADJ()
See Also
========
inverse_LU
inverse_GE
inverse_ADJ
Raises
------
ValueError
If the determinant of the matrix is zero.
CASE 2: If the matrix is a sparse matrix.
Return the matrix inverse using Cholesky or LDL (default).
kwargs
======
method : ('CH', 'LDL')
Notes
=====
According to the ``method`` keyword, it calls the appropriate method:
LDL ... inverse_LDL(); default
CH .... inverse_CH()
Raises
------
ValueError
If the determinant of the matrix is zero.
"""
if not self.is_square:
raise NonSquareMatrixError()
if method is not None:
kwargs['method'] = method
return self._eval_inverse(**kwargs)
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)
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 LDLdecomposition(self, hermitian=True):
"""Returns the LDL Decomposition (L, D) of matrix A,
such that L * D * L.H == A if hermitian flag is True, or
L * D * L.T == A if hermitian is False.
This method eliminates the use of square root.
Further this ensures that all the diagonal entries of L are 1.
A must be a Hermitian positive-definite matrix if hermitian is True,
or a symmetric matrix otherwise.
Examples
========
>>> from sympy.matrices import Matrix, eye
>>> A = Matrix(((25, 15, -5), (15, 18, 0), (-5, 0, 11)))
>>> L, D = A.LDLdecomposition()
>>> L
Matrix([
[ 1, 0, 0],
[ 3/5, 1, 0],
[-1/5, 1/3, 1]])
>>> D
Matrix([
[25, 0, 0],
[ 0, 9, 0],
[ 0, 0, 9]])
>>> L * D * L.T * A.inv() == eye(A.rows)
True
The matrix can have complex entries:
>>> from sympy import I
>>> A = Matrix(((9, 3*I), (-3*I, 5)))
>>> L, D = A.LDLdecomposition()
>>> L
Matrix([
[ 1, 0],
[-I/3, 1]])
>>> D
Matrix([
[9, 0],
[0, 4]])
>>> L*D*L.H == A
True
See Also
========
cholesky
LUdecomposition
QRdecomposition
"""
if not self.is_square:
raise NonSquareMatrixError("Matrix must be square.")
if hermitian and not self.is_hermitian:
raise ValueError("Matrix must be Hermitian.")
if not hermitian and not self.is_symmetric():
raise ValueError("Matrix must be symmetric.")
return self._LDLdecomposition(hermitian=hermitian)
def LDLsolve(self, 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
========
LDLdecomposition
lower_triangular_solve
upper_triangular_solve
gauss_jordan_solve
cholesky_solve
diagonal_solve
LUsolve
QRsolve
pinv_solve
"""
hermitian = True
if self.is_symmetric():
hermitian = False
L, D = self.LDLdecomposition(hermitian=hermitian)
elif self.is_hermitian:
L, D = self.LDLdecomposition(hermitian=hermitian)
elif self.rows >= self.cols:
L, D = (self.H * self).LDLdecomposition(hermitian=hermitian)
rhs = self.H * rhs
else:
raise NotImplementedError('Under-determined System. '
'Try M.gauss_jordan_solve(rhs)')
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 lower_triangular_solve(self, 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 self.is_square:
raise NonSquareMatrixError("Matrix must be square.")
if rhs.rows != self.rows:
raise ShapeError("Matrices size mismatch.")
if not self.is_lower:
raise ValueError("Matrix must be lower triangular.")
return self._lower_triangular_solve(rhs)
def LUdecomposition(self,
iszerofunc=_iszero,
simpfunc=None,
rankcheck=False):
"""Returns (L, U, perm) where L is a lower triangular matrix with unit
diagonal, U is an upper triangular matrix, and perm is a list of row
swap index pairs. If A is the original matrix, then
A = (L*U).permuteBkwd(perm), and the row permutation matrix P such
that P*A = L*U can be computed by P=eye(A.row).permuteFwd(perm).
See documentation for LUCombined for details about the keyword argument
rankcheck, iszerofunc, and simpfunc.
Examples
========
>>> from sympy import Matrix
>>> a = Matrix([[4, 3], [6, 3]])
>>> L, U, _ = a.LUdecomposition()
>>> L
Matrix([
[ 1, 0],
[3/2, 1]])
>>> U
Matrix([
[4, 3],
[0, -3/2]])
See Also
========
cholesky
LDLdecomposition
QRdecomposition
LUdecomposition_Simple
LUdecompositionFF
LUsolve
"""
combined, p = self.LUdecomposition_Simple(iszerofunc=iszerofunc,
simpfunc=simpfunc,
rankcheck=rankcheck)
# L is lower triangular self.rows x self.rows
# U is upper triangular self.rows x self.cols
# L has unit diagonal. For each column in combined, the subcolumn
# below the diagonal of combined is shared by L.
# If L has more columns than combined, then the remaining subcolumns
# below the diagonal of L are zero.
# The upper triangular portion of L and combined are equal.
def entry_L(i, j):
if i < j:
# Super diagonal entry
return S.Zero
elif i == j:
return S.One
elif j < combined.cols:
return combined[i, j]
# Subdiagonal entry of L with no corresponding
# entry in combined
return S.Zero
def entry_U(i, j):
return S.Zero if i > j else combined[i, j]
L = self._new(combined.rows, combined.rows, entry_L)
U = self._new(combined.rows, combined.cols, entry_U)
return L, U, p
def LUdecomposition_Simple(self,
iszerofunc=_iszero,
simpfunc=None,
rankcheck=False):
"""Compute an lu decomposition of m x n matrix A, where P*A = L*U
* L is m x m lower triangular with unit diagonal
* U is m x n upper triangular
* P is an m x m permutation matrix
Returns an m x n matrix lu, and an m element list perm where each
element of perm is a pair of row exchange indices.
The factors L and U are stored in lu as follows:
The subdiagonal elements of L are stored in the subdiagonal elements
of lu, that is lu[i, j] = L[i, j] whenever i > j.
The elements on the diagonal of L are all 1, and are not explicitly
stored.
U is stored in the upper triangular portion of lu, that is
lu[i ,j] = U[i, j] whenever i <= j.
The output matrix can be visualized as:
Matrix([
[u, u, u, u],
[l, u, u, u],
[l, l, u, u],
[l, l, l, u]])
where l represents a subdiagonal entry of the L factor, and u
represents an entry from the upper triangular entry of the U
factor.
perm is a list row swap index pairs such that if A is the original
matrix, then A = (L*U).permuteBkwd(perm), and the row permutation
matrix P such that ``P*A = L*U`` can be computed by
``P=eye(A.row).permuteFwd(perm)``.
The keyword argument rankcheck determines if this function raises a
ValueError when passed a matrix whose rank is strictly less than
min(num rows, num cols). The default behavior is to decompose a rank
deficient matrix. Pass rankcheck=True to raise a
ValueError instead. (This mimics the previous behavior of this function).
The keyword arguments iszerofunc and simpfunc are used by the pivot
search algorithm.
iszerofunc is a callable that returns a boolean indicating if its
input is zero, or None if it cannot make the determination.
simpfunc is a callable that simplifies its input.
The default is simpfunc=None, which indicate that the pivot search
algorithm should not attempt to simplify any candidate pivots.
If simpfunc fails to simplify its input, then it must return its input
instead of a copy.
When a matrix contains symbolic entries, the pivot search algorithm
differs from the case where every entry can be categorized as zero or
nonzero.
The algorithm searches column by column through the submatrix whose
top left entry coincides with the pivot position.
If it exists, the pivot is the first entry in the current search
column that iszerofunc guarantees is nonzero.
If no such candidate exists, then each candidate pivot is simplified
if simpfunc is not None.
The search is repeated, with the difference that a candidate may be
the pivot if ``iszerofunc()`` cannot guarantee that it is nonzero.
In the second search the pivot is the first candidate that
iszerofunc can guarantee is nonzero.
If no such candidate exists, then the pivot is the first candidate
for which iszerofunc returns None.
If no such candidate exists, then the search is repeated in the next
column to the right.
The pivot search algorithm differs from the one in `rref()`, which
relies on ``_find_reasonable_pivot()``.
Future versions of ``LUdecomposition_simple()`` may use
``_find_reasonable_pivot()``.
See Also
========
LUdecomposition
LUdecompositionFF
LUsolve
"""
if rankcheck:
# https://github.com/sympy/sympy/issues/9796
pass
if self.rows == 0 or self.cols == 0:
# Define LU decomposition of a matrix with no entries as a matrix
# of the same dimensions with all zero entries.
return self.zeros(self.rows, self.cols), []
lu = self.as_mutable()
row_swaps = []
pivot_col = 0
for pivot_row in range(0, lu.rows - 1):
# Search for pivot. Prefer entry that iszeropivot determines
# is nonzero, over entry that iszeropivot cannot guarantee
# is zero.
# XXX `_find_reasonable_pivot` uses slow zero testing. Blocked by bug #10279
# Future versions of LUdecomposition_simple can pass iszerofunc and simpfunc
# to _find_reasonable_pivot().
# In pass 3 of _find_reasonable_pivot(), the predicate in `if x.equals(S.Zero):`
# calls sympy.simplify(), and not the simplification function passed in via
# the keyword argument simpfunc.
iszeropivot = True
while pivot_col != self.cols and iszeropivot:
sub_col = (lu[r, pivot_col] for r in range(pivot_row, self.rows))
pivot_row_offset, pivot_value, is_assumed_non_zero, ind_simplified_pairs =\
_find_reasonable_pivot_naive(sub_col, iszerofunc, simpfunc)
iszeropivot = pivot_value is None
if iszeropivot:
# All candidate pivots in this column are zero.
# Proceed to next column.
pivot_col += 1
if rankcheck and pivot_col != pivot_row:
# All entries including and below the pivot position are
# zero, which indicates that the rank of the matrix is
# strictly less than min(num rows, num cols)
# Mimic behavior of previous implementation, by throwing a
# ValueError.
raise ValueError("Rank of matrix is strictly less than"
" number of rows or columns."
" Pass keyword argument"
" rankcheck=False to compute"
" the LU decomposition of this matrix.")
candidate_pivot_row = None if pivot_row_offset is None else pivot_row + pivot_row_offset
if candidate_pivot_row is None and iszeropivot:
# If candidate_pivot_row is None and iszeropivot is True
# after pivot search has completed, then the submatrix
# below and to the right of (pivot_row, pivot_col) is
# all zeros, indicating that Gaussian elimination is
# complete.
return lu, row_swaps
# Update entries simplified during pivot search.
for offset, val in ind_simplified_pairs:
lu[pivot_row + offset, pivot_col] = val
if pivot_row != candidate_pivot_row:
# Row swap book keeping:
# Record which rows were swapped.
# Update stored portion of L factor by multiplying L on the
# left and right with the current permutation.
# Swap rows of U.
row_swaps.append([pivot_row, candidate_pivot_row])
# Update L.
lu[pivot_row, 0:pivot_row], lu[candidate_pivot_row, 0:pivot_row] = \
lu[candidate_pivot_row, 0:pivot_row], lu[pivot_row, 0:pivot_row]
# Swap pivot row of U with candidate pivot row.
lu[pivot_row, pivot_col:lu.cols], lu[candidate_pivot_row, pivot_col:lu.cols] = \
lu[candidate_pivot_row, pivot_col:lu.cols], lu[pivot_row, pivot_col:lu.cols]
# Introduce zeros below the pivot by adding a multiple of the
# pivot row to a row under it, and store the result in the
# row under it.
# Only entries in the target row whose index is greater than
# start_col may be nonzero.
start_col = pivot_col + 1
for row in range(pivot_row + 1, lu.rows):
# Store factors of L in the subcolumn below
# (pivot_row, pivot_row).
lu[row, pivot_row] =\
lu[row, pivot_col]/lu[pivot_row, pivot_col]
# Form the linear combination of the pivot row and the current
# row below the pivot row that zeros the entries below the pivot.
# Employing slicing instead of a loop here raises
# NotImplementedError: Cannot add Zero to MutableSparseMatrix
# in sympy/matrices/tests/test_sparse.py.
# c = pivot_row + 1 if pivot_row == pivot_col else pivot_col
for c in range(start_col, lu.cols):
lu[row, c] = lu[row, c] - lu[row, pivot_row]*lu[pivot_row, c]
if pivot_row != pivot_col:
# matrix rank < min(num rows, num cols),
# so factors of L are not stored directly below the pivot.
# These entries are zero by construction, so don't bother
# computing them.
for row in range(pivot_row + 1, lu.rows):
lu[row, pivot_col] = S.Zero
pivot_col += 1
if pivot_col == lu.cols:
# All candidate pivots are zero implies that Gaussian
# elimination is complete.
return lu, row_swaps
if rankcheck:
if iszerofunc(
lu[Min(lu.rows, lu.cols) - 1, Min(lu.rows, lu.cols) - 1]):
raise ValueError("Rank of matrix is strictly less than"
" number of rows or columns."
" Pass keyword argument"
" rankcheck=False to compute"
" the LU decomposition of this matrix.")
return lu, row_swaps
def LUdecompositionFF(self):
"""Compute a fraction-free LU decomposition.
Returns 4 matrices P, L, D, U such that PA = L D**-1 U.
If the elements of the matrix belong to some integral domain I, then all
elements of L, D and U are guaranteed to belong to I.
**Reference**
- W. Zhou & D.J. Jeffrey, "Fraction-free matrix factors: new forms
for LU and QR factors". Frontiers in Computer Science in China,
Vol 2, no. 1, pp. 67-80, 2008.
See Also
========
LUdecomposition
LUdecomposition_Simple
LUsolve
"""
from sympy.matrices import SparseMatrix
zeros = SparseMatrix.zeros
eye = SparseMatrix.eye
n, m = self.rows, self.cols
U, L, P = self.as_mutable(), eye(n), eye(n)
DD = zeros(n, n)
oldpivot = 1
for k in range(n - 1):
if U[k, k] == 0:
for kpivot in range(k + 1, n):
if U[kpivot, k]:
break
else:
raise ValueError("Matrix is not full rank")
U[k, k:], U[kpivot, k:] = U[kpivot, k:], U[k, k:]
L[k, :k], L[kpivot, :k] = L[kpivot, :k], L[k, :k]
P[k, :], P[kpivot, :] = P[kpivot, :], P[k, :]
L[k, k] = Ukk = U[k, k]
DD[k, k] = oldpivot * Ukk
for i in range(k + 1, n):
L[i, k] = Uik = U[i, k]
for j in range(k + 1, m):
U[i, j] = (Ukk * U[i, j] - U[k, j] * Uik) / oldpivot
U[i, k] = 0
oldpivot = Ukk
DD[n - 1, n - 1] = oldpivot
return P, L, DD, U
def LUsolve(self, rhs, iszerofunc=_iszero):
"""Solve the linear system Ax = rhs for x where A = self.
This is for symbolic matrices, for real or complex ones use
mpmath.lu_solve or mpmath.qr_solve.
See Also
========
lower_triangular_solve
upper_triangular_solve
gauss_jordan_solve
cholesky_solve
diagonal_solve
LDLsolve
QRsolve
pinv_solve
LUdecomposition
"""
if rhs.rows != self.rows:
raise ShapeError(
"`self` and `rhs` must have the same number of rows.")
m = self.rows
n = self.cols
if m < n:
raise NotImplementedError("Underdetermined systems not supported.")
A, perm = self.LUdecomposition_Simple(iszerofunc=_iszero)
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: 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: x - y * scale)
scale = A[i, i]
b.row_op(i, lambda x, _: x / scale)
return rhs.__class__(b)
def multiply(self, b):
"""Returns self*b
See Also
========
dot
cross
multiply_elementwise
"""
return self * b
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 == S.Infinity: # max(abs(x))
return Max(*[abs(i) for i in vals])
elif ord == 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(1) / 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 == 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,
string_types) 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 pinv_solve(self, 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
========
lower_triangular_solve
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 = self
A_pinv = self.pinv()
if arbitrary_matrix is None:
rows, cols = A.cols, B.cols
w = symbols('w:{0}_:{1}'.format(rows, cols), cls=Dummy)
arbitrary_matrix = self.__class__(cols, rows, w).T
return A_pinv * B + (eye(A.cols) - A_pinv * A) * arbitrary_matrix
def pinv(self):
"""Calculate the Moore-Penrose pseudoinverse of the matrix.
The Moore-Penrose pseudoinverse exists and is unique for any matrix.
If the matrix is invertible, the pseudoinverse is the same as the
inverse.
Examples
========
>>> from sympy import Matrix
>>> Matrix([[1, 2, 3], [4, 5, 6]]).pinv()
Matrix([
[-17/18, 4/9],
[ -1/9, 1/9],
[ 13/18, -2/9]])
See Also
========
inv
pinv_solve
References
==========
.. [1] https://en.wikipedia.org/wiki/Moore-Penrose_pseudoinverse
"""
A = self
AH = self.H
# Trivial case: pseudoinverse of all-zero matrix is its transpose.
if A.is_zero:
return AH
try:
if self.rows >= self.cols:
return (AH * A).inv() * AH
else:
return AH * (A * AH).inv()
except ValueError:
# Matrix is not full rank, so A*AH cannot be inverted.
pass
try:
# However, A*AH is Hermitian, so we can diagonalize it.
if self.rows >= self.cols:
P, D = (AH * A).diagonalize(normalize=True)
D_pinv = D.applyfunc(lambda x: 0 if _iszero(x) else 1 / x)
return P * D_pinv * P.H * AH
else:
P, D = (A * AH).diagonalize(normalize=True)
D_pinv = D.applyfunc(lambda x: 0 if _iszero(x) else 1 / x)
return AH * P * D_pinv * P.H
except MatrixError:
raise NotImplementedError('pinv for rank-deficient matrices where diagonalization '
'of A.H*A fails is not supported yet.')
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 QRdecomposition(self):
"""Return Q, R where A = Q*R, Q is orthogonal and R is upper triangular.
Examples
========
This is the example from wikipedia:
>>> from sympy import Matrix
>>> A = Matrix([[12, -51, 4], [6, 167, -68], [-4, 24, -41]])
>>> Q, R = A.QRdecomposition()
>>> Q
Matrix([
[ 6/7, -69/175, -58/175],
[ 3/7, 158/175, 6/175],
[-2/7, 6/35, -33/35]])
>>> R
Matrix([
[14, 21, -14],
[ 0, 175, -70],
[ 0, 0, 35]])
>>> A == Q*R
True
QR factorization of an identity matrix:
>>> A = Matrix([[1, 0, 0], [0, 1, 0], [0, 0, 1]])
>>> Q, R = A.QRdecomposition()
>>> Q
Matrix([
[1, 0, 0],
[0, 1, 0],
[0, 0, 1]])
>>> R
Matrix([
[1, 0, 0],
[0, 1, 0],
[0, 0, 1]])
See Also
========
cholesky
LDLdecomposition
LUdecomposition
QRsolve
"""
cls = self.__class__
mat = self.as_mutable()
n = mat.rows
m = mat.cols
ranked = list()
# Pad with additional rows to make wide matrices square
# nOrig keeps track of original size so zeros can be trimmed from Q
if n < m:
nOrig = n
n = m
mat = mat.col_join(mat.zeros(n - nOrig, m))
else:
nOrig = n
Q, R = mat.zeros(n, m), mat.zeros(m)
for j in range(m): # for each column vector
tmp = mat[:, j] # take original v
for i in range(j):
# subtract the project of mat on new vector
R[i, j] = Q[:, i].dot(mat[:, j])
tmp -= Q[:, i] * R[i, j]
tmp.expand()
# normalize it
R[j, j] = tmp.norm()
if not R[j, j].is_zero:
ranked.append(j)
Q[:, j] = tmp / R[j, j]
if len(ranked) != 0:
return (
cls(Q.extract(range(nOrig), ranked)),
cls(R.extract(ranked, range(R.cols)))
)
else:
# Trivial case handling for zero-rank matrix
# Force Q as matrix containing standard basis vectors
for i in range(Min(nOrig, m)):
Q[i, i] = 1
return (
cls(Q.extract(range(nOrig), range(Min(nOrig, m)))),
cls(R.extract(range(Min(nOrig, m)), range(R.cols)))
)
def QRsolve(self, b):
"""Solve the linear system 'Ax = b'.
'self' 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
========
lower_triangular_solve
upper_triangular_solve
gauss_jordan_solve
cholesky_solve
diagonal_solve
LDLsolve
LUsolve
pinv_solve
QRdecomposition
"""
Q, R = self.as_mutable().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]
x.append(tmp / R[j, j])
return self._new([row._mat for row in reversed(x)])
def solve_least_squares(self, 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 self 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 self.cholesky_solve(rhs)
elif method == 'QR':
return self.QRsolve(rhs)
elif method == 'LDL':
return self.LDLsolve(rhs)
elif method == 'PINV':
return self.pinv_solve(rhs)
else:
t = self.H
return (t * self).solve(t * rhs, method=method)
def solve(self, 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'``, 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 ``self`` is not square, a ``ValueError`` and a different routine
for solving the system will be suggested.
"""
if method == 'GJ':
try:
soln, param = self.gauss_jordan_solve(rhs)
if param:
raise ValueError("Matrix det == 0; not invertible. "
"Try `self.gauss_jordan_solve(rhs)` to obtain a parametric solution.")
except ValueError:
# raise same error as in inv:
self.zeros(1).inv()
return soln
elif method == 'LU':
return self.LUsolve(rhs)
elif method == 'CH':
return self.cholesky_solve(rhs)
elif method == 'QR':
return self.QRsolve(rhs)
elif method == 'LDL':
return self.LDLsolve(rhs)
elif method == 'PINV':
return self.pinv_solve(rhs)
else:
return self.inv(method=method)*rhs
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 upper_triangular_solve(self, 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 self.is_square:
raise NonSquareMatrixError("Matrix must be square.")
if rhs.rows != self.rows:
raise TypeError("Matrix size mismatch.")
if not self.is_upper:
raise TypeError("Matrix is not upper triangular.")
return self._upper_triangular_solve(rhs)
def vech(self, diagonal=True, check_symmetry=True):
"""Return the unique elements of a symmetric Matrix as a one column matrix
by stacking the elements in the lower triangle.
Arguments:
diagonal -- include the diagonal cells of self or not
check_symmetry -- checks symmetry of self but not completely reliably
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]])
See Also
========
vec
"""
from sympy.matrices import zeros
c = self.cols
if c != self.rows:
raise ShapeError("Matrix must be square")
if check_symmetry:
self.simplify()
if self != self.transpose():
raise ValueError(
"Matrix appears to be asymmetric; consider check_symmetry=False")
count = 0
if diagonal:
v = zeros(c * (c + 1) // 2, 1)
for j in range(c):
for i in range(j, c):
v[count] = self[i, j]
count += 1
else:
v = zeros(c * (c - 1) // 2, 1)
for j in range(c):
for i in range(j + 1, c):
v[count] = self[i, j]
count += 1
return v
@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)
def _find_reasonable_pivot(col, iszerofunc=_iszero, simpfunc=_simplify):
""" Find the lowest index of an item in `col` that is
suitable for a pivot. If `col` consists only of
Floats, the pivot with the largest norm is returned.
Otherwise, the first element where `iszerofunc` returns
False is used. If `iszerofunc` doesn't return false,
items are simplified and retested until a suitable
pivot is found.
Returns a 4-tuple
(pivot_offset, pivot_val, assumed_nonzero, newly_determined)
where pivot_offset is the index of the pivot, pivot_val is
the (possibly simplified) value of the pivot, assumed_nonzero
is True if an assumption that the pivot was non-zero
was made without being proved, and newly_determined are
elements that were simplified during the process of pivot
finding."""
newly_determined = []
col = list(col)
# a column that contains a mix of floats and integers
# but at least one float is considered a numerical
# column, and so we do partial pivoting
if all(isinstance(x, (Float, Integer)) for x in col) and any(
isinstance(x, Float) for x in col):
col_abs = [abs(x) for x in col]
max_value = max(col_abs)
if iszerofunc(max_value):
# just because iszerofunc returned True, doesn't
# mean the value is numerically zero. Make sure
# to replace all entries with numerical zeros
if max_value != 0:
newly_determined = [(i, 0) for i, x in enumerate(col) if x != 0]
return (None, None, False, newly_determined)
index = col_abs.index(max_value)
return (index, col[index], False, newly_determined)
# PASS 1 (iszerofunc directly)
possible_zeros = []
for i, x in enumerate(col):
is_zero = iszerofunc(x)
# is someone wrote a custom iszerofunc, it may return
# BooleanFalse or BooleanTrue instead of True or False,
# so use == for comparison instead of `is`
if is_zero == False:
# we found something that is definitely not zero
return (i, x, False, newly_determined)
possible_zeros.append(is_zero)
# by this point, we've found no certain non-zeros
if all(possible_zeros):
# if everything is definitely zero, we have
# no pivot
return (None, None, False, newly_determined)
# PASS 2 (iszerofunc after simplify)
# we haven't found any for-sure non-zeros, so
# go through the elements iszerofunc couldn't
# make a determination about and opportunistically
# simplify to see if we find something
for i, x in enumerate(col):
if possible_zeros[i] is not None:
continue
simped = simpfunc(x)
is_zero = iszerofunc(simped)
if is_zero == True or is_zero == False:
newly_determined.append((i, simped))
if is_zero == False:
return (i, simped, False, newly_determined)
possible_zeros[i] = is_zero
# after simplifying, some things that were recognized
# as zeros might be zeros
if all(possible_zeros):
# if everything is definitely zero, we have
# no pivot
return (None, None, False, newly_determined)
# PASS 3 (.equals(0))
# some expressions fail to simplify to zero, but
# `.equals(0)` evaluates to True. As a last-ditch
# attempt, apply `.equals` to these expressions
for i, x in enumerate(col):
if possible_zeros[i] is not None:
continue
if x.equals(S.Zero):
# `.iszero` may return False with
# an implicit assumption (e.g., `x.equals(0)`
# when `x` is a symbol), so only treat it
# as proved when `.equals(0)` returns True
possible_zeros[i] = True
newly_determined.append((i, S.Zero))
if all(possible_zeros):
return (None, None, False, newly_determined)
# at this point there is nothing that could definitely
# be a pivot. To maintain compatibility with existing
# behavior, we'll assume that an illdetermined thing is
# non-zero. We should probably raise a warning in this case
i = possible_zeros.index(None)
return (i, col[i], True, newly_determined)
def _find_reasonable_pivot_naive(col, iszerofunc=_iszero, simpfunc=None):
"""
Helper that computes the pivot value and location from a
sequence of contiguous matrix column elements. As a side effect
of the pivot search, this function may simplify some of the elements
of the input column. A list of these simplified entries and their
indices are also returned.
This function mimics the behavior of _find_reasonable_pivot(),
but does less work trying to determine if an indeterminate candidate
pivot simplifies to zero. This more naive approach can be much faster,
with the trade-off that it may erroneously return a pivot that is zero.
`col` is a sequence of contiguous column entries to be searched for
a suitable pivot.
`iszerofunc` is a callable that returns a Boolean that indicates
if its input is zero, or None if no such determination can be made.
`simpfunc` is a callable that simplifies its input. It must return
its input if it does not simplify its input. Passing in
`simpfunc=None` indicates that the pivot search should not attempt
to simplify any candidate pivots.
Returns a 4-tuple:
(pivot_offset, pivot_val, assumed_nonzero, newly_determined)
`pivot_offset` is the sequence index of the pivot.
`pivot_val` is the value of the pivot.
pivot_val and col[pivot_index] are equivalent, but will be different
when col[pivot_index] was simplified during the pivot search.
`assumed_nonzero` is a boolean indicating if the pivot cannot be
guaranteed to be zero. If assumed_nonzero is true, then the pivot
may or may not be non-zero. If assumed_nonzero is false, then
the pivot is non-zero.
`newly_determined` is a list of index-value pairs of pivot candidates
that were simplified during the pivot search.
"""
# indeterminates holds the index-value pairs of each pivot candidate
# that is neither zero or non-zero, as determined by iszerofunc().
# If iszerofunc() indicates that a candidate pivot is guaranteed
# non-zero, or that every candidate pivot is zero then the contents
# of indeterminates are unused.
# Otherwise, the only viable candidate pivots are symbolic.
# In this case, indeterminates will have at least one entry,
# and all but the first entry are ignored when simpfunc is None.
indeterminates = []
for i, col_val in enumerate(col):
col_val_is_zero = iszerofunc(col_val)
if col_val_is_zero == False:
# This pivot candidate is non-zero.
return i, col_val, False, []
elif col_val_is_zero is None:
# The candidate pivot's comparison with zero
# is indeterminate.
indeterminates.append((i, col_val))
if len(indeterminates) == 0:
# All candidate pivots are guaranteed to be zero, i.e. there is
# no pivot.
return None, None, False, []
if simpfunc is None:
# Caller did not pass in a simplification function that might
# determine if an indeterminate pivot candidate is guaranteed
# to be nonzero, so assume the first indeterminate candidate
# is non-zero.
return indeterminates[0][0], indeterminates[0][1], True, []
# newly_determined holds index-value pairs of candidate pivots
# that were simplified during the search for a non-zero pivot.
newly_determined = []
for i, col_val in indeterminates:
tmp_col_val = simpfunc(col_val)
if id(col_val) != id(tmp_col_val):
# simpfunc() simplified this candidate pivot.
newly_determined.append((i, tmp_col_val))
if iszerofunc(tmp_col_val) == False:
# Candidate pivot simplified to a guaranteed non-zero value.
return i, tmp_col_val, False, newly_determined
return indeterminates[0][0], indeterminates[0][1], True, newly_determined
|
736f4959c72a81129ccf40fcacf35cc867894fce6bca6edbc3b452ee659c942c
|
""" rewrite of lambdify - This stuff is not stable at all.
It is for internal use in the new plotting module.
It may (will! see the Q'n'A in the source) be rewritten.
It's completely self contained. Especially it does not use lambdarepr.
It does not aim to replace the current lambdify. Most importantly it will never
ever support anything else than sympy expressions (no Matrices, dictionaries
and so on).
"""
from __future__ import print_function, division
import re
from sympy import Symbol, NumberSymbol, I, zoo, oo
from sympy.core.compatibility import exec_
from sympy.utilities.iterables import numbered_symbols
# We parse the expression string into a tree that identifies functions. Then
# we translate the names of the functions and we translate also some strings
# that are not names of functions (all this according to translation
# dictionaries).
# If the translation goes to another module (like numpy) the
# module is imported and 'func' is translated to 'module.func'.
# If a function can not be translated, the inner nodes of that part of the
# tree are not translated. So if we have Integral(sqrt(x)), sqrt is not
# translated to np.sqrt and the Integral does not crash.
# A namespace for all this is generated by crawling the (func, args) tree of
# the expression. The creation of this namespace involves many ugly
# workarounds.
# The namespace consists of all the names needed for the sympy expression and
# all the name of modules used for translation. Those modules are imported only
# as a name (import numpy as np) in order to keep the namespace small and
# manageable.
# Please, if there is a bug, do not try to fix it here! Rewrite this by using
# the method proposed in the last Q'n'A below. That way the new function will
# work just as well, be just as simple, but it wont need any new workarounds.
# If you insist on fixing it here, look at the workarounds in the function
# sympy_expression_namespace and in lambdify.
# Q: Why are you not using python abstract syntax tree?
# A: Because it is more complicated and not much more powerful in this case.
# Q: What if I have Symbol('sin') or g=Function('f')?
# A: You will break the algorithm. We should use srepr to defend against this?
# The problem with Symbol('sin') is that it will be printed as 'sin'. The
# parser will distinguish it from the function 'sin' because functions are
# detected thanks to the opening parenthesis, but the lambda expression won't
# understand the difference if we have also the sin function.
# The solution (complicated) is to use srepr and maybe ast.
# The problem with the g=Function('f') is that it will be printed as 'f' but in
# the global namespace we have only 'g'. But as the same printer is used in the
# constructor of the namespace there will be no problem.
# Q: What if some of the printers are not printing as expected?
# A: The algorithm wont work. You must use srepr for those cases. But even
# srepr may not print well. All problems with printers should be considered
# bugs.
# Q: What about _imp_ functions?
# A: Those are taken care for by evalf. A special case treatment will work
# faster but it's not worth the code complexity.
# Q: Will ast fix all possible problems?
# A: No. You will always have to use some printer. Even srepr may not work in
# some cases. But if the printer does not work, that should be considered a
# bug.
# Q: Is there same way to fix all possible problems?
# A: Probably by constructing our strings ourself by traversing the (func,
# args) tree and creating the namespace at the same time. That actually sounds
# good.
from sympy.external import import_module
import warnings
#TODO debugging output
class vectorized_lambdify(object):
""" Return a sufficiently smart, vectorized and lambdified function.
Returns only reals.
This function uses experimental_lambdify to created a lambdified
expression ready to be used with numpy. Many of the functions in sympy
are not implemented in numpy so in some cases we resort to python cmath or
even to evalf.
The following translations are tried:
only numpy complex
- on errors raised by sympy trying to work with ndarray:
only python cmath and then vectorize complex128
When using python cmath there is no need for evalf or float/complex
because python cmath calls those.
This function never tries to mix numpy directly with evalf because numpy
does not understand sympy Float. If this is needed one can use the
float_wrap_evalf/complex_wrap_evalf options of experimental_lambdify or
better one can be explicit about the dtypes that numpy works with.
Check numpy bug http://projects.scipy.org/numpy/ticket/1013 to know what
types of errors to expect.
"""
def __init__(self, args, expr):
self.args = args
self.expr = expr
self.lambda_func = experimental_lambdify(args, expr, use_np=True)
self.vector_func = self.lambda_func
self.failure = False
def __call__(self, *args):
np = import_module('numpy')
np_old_err = np.seterr(invalid='raise')
try:
temp_args = (np.array(a, dtype=np.complex) for a in args)
results = self.vector_func(*temp_args)
results = np.ma.masked_where(
np.abs(results.imag) > 1e-7 * np.abs(results),
results.real, copy=False)
except Exception as e:
#DEBUG: print 'Error', type(e), e
if ((isinstance(e, TypeError)
and 'unhashable type: \'numpy.ndarray\'' in str(e))
or
(isinstance(e, ValueError)
and ('Invalid limits given:' in str(e)
or 'negative dimensions are not allowed' in str(e) # XXX
or 'sequence too large; must be smaller than 32' in str(e)))): # XXX
# Almost all functions were translated to numpy, but some were
# left as sympy functions. They received an ndarray as an
# argument and failed.
# sin(ndarray(...)) raises "unhashable type"
# Integral(x, (x, 0, ndarray(...))) raises "Invalid limits"
# other ugly exceptions that are not well understood (marked with XXX)
# TODO: Cleanup the ugly special cases marked with xxx above.
# Solution: use cmath and vectorize the final lambda.
self.lambda_func = experimental_lambdify(
self.args, self.expr, use_python_cmath=True)
self.vector_func = np.vectorize(
self.lambda_func, otypes=[np.complex])
results = self.vector_func(*args)
results = np.ma.masked_where(
np.abs(results.imag) > 1e-7 * np.abs(results),
results.real, copy=False)
else:
# Complete failure. One last try with no translations, only
# wrapping in complex((...).evalf()) and returning the real
# part.
if self.failure:
raise e
else:
self.failure = True
self.lambda_func = experimental_lambdify(
self.args, self.expr, use_evalf=True,
complex_wrap_evalf=True)
self.vector_func = np.vectorize(
self.lambda_func, otypes=[np.complex])
results = self.vector_func(*args)
results = np.ma.masked_where(
np.abs(results.imag) > 1e-7 * np.abs(results),
results.real, copy=False)
warnings.warn('The evaluation of the expression is'
' problematic. We are trying a failback method'
' that may still work. Please report this as a bug.')
finally:
np.seterr(**np_old_err)
return results
class lambdify(object):
"""Returns the lambdified function.
This function uses experimental_lambdify to create a lambdified
expression. It uses cmath to lambdify the expression. If the function
is not implemented in python cmath, python cmath calls evalf on those
functions.
"""
def __init__(self, args, expr):
self.args = args
self.expr = expr
self.lambda_func = experimental_lambdify(args, expr, use_evalf=True,
use_python_cmath=True)
self.failure = False
def __call__(self, args, kwargs = {}):
if not self.lambda_func.use_python_math:
args = complex(args)
try:
#The result can be sympy.Float. Hence wrap it with complex type.
result = complex(self.lambda_func(args))
if abs(result.imag) > 1e-7 * abs(result):
return None
else:
return result.real
except Exception as e:
# The exceptions raised by sympy, cmath are not consistent and
# hence it is not possible to specify all the exceptions that
# are to be caught. Presently there are no cases for which the code
# reaches this block other than ZeroDivisionError and complex
# comparison. Also the exception is caught only once. If the
# exception repeats itself,
# then it is not caught and the corresponding error is raised.
# XXX: Remove catching all exceptions once the plotting module
# is heavily tested.
if isinstance(e, ZeroDivisionError):
return None
elif isinstance(e, TypeError) and ('no ordering relation is'
' defined for complex numbers'
in str(e) or 'unorderable '
'types' in str(e) or "not "
"supported between instances of"
in str(e)):
self.lambda_func = experimental_lambdify(self.args, self.expr,
use_evalf=True,
use_python_math=True)
result = self.lambda_func(args.real)
return result
else:
if self.failure:
raise e
#Failure
#Try wrapping it with complex(..).evalf()
self.failure = True
self.lambda_func = experimental_lambdify(self.args, self.expr,
use_evalf=True,
complex_wrap_evalf=True)
result = self.lambda_func(args)
warnings.warn('The evaluation of the expression is'
' problematic. We are trying a failback method'
' that may still work. Please report this as a bug.')
if abs(result.imag) > 1e-7 * abs(result):
return None
else:
return result.real
def experimental_lambdify(*args, **kwargs):
l = Lambdifier(*args, **kwargs)
return l
class Lambdifier(object):
def __init__(self, args, expr, print_lambda=False, use_evalf=False,
float_wrap_evalf=False, complex_wrap_evalf=False,
use_np=False, use_python_math=False, use_python_cmath=False,
use_interval=False):
self.print_lambda = print_lambda
self.use_evalf = use_evalf
self.float_wrap_evalf = float_wrap_evalf
self.complex_wrap_evalf = complex_wrap_evalf
self.use_np = use_np
self.use_python_math = use_python_math
self.use_python_cmath = use_python_cmath
self.use_interval = use_interval
# Constructing the argument string
# - check
if not all([isinstance(a, Symbol) for a in args]):
raise ValueError('The arguments must be Symbols.')
# - use numbered symbols
syms = numbered_symbols(exclude=expr.free_symbols)
newargs = [next(syms) for i in args]
expr = expr.xreplace(dict(zip(args, newargs)))
argstr = ', '.join([str(a) for a in newargs])
del syms, newargs, args
# Constructing the translation dictionaries and making the translation
self.dict_str = self.get_dict_str()
self.dict_fun = self.get_dict_fun()
exprstr = str(expr)
# the & and | operators don't work on tuples, see discussion #12108
exprstr = exprstr.replace(" & "," and ").replace(" | "," or ")
newexpr = self.tree2str_translate(self.str2tree(exprstr))
# Constructing the namespaces
namespace = {}
namespace.update(self.sympy_atoms_namespace(expr))
namespace.update(self.sympy_expression_namespace(expr))
# XXX Workaround
# Ugly workaround because Pow(a,Half) prints as sqrt(a)
# and sympy_expression_namespace can not catch it.
from sympy import sqrt
namespace.update({'sqrt': sqrt})
namespace.update({'Eq': lambda x, y: x == y})
# End workaround.
if use_python_math:
namespace.update({'math': __import__('math')})
if use_python_cmath:
namespace.update({'cmath': __import__('cmath')})
if use_np:
try:
namespace.update({'np': __import__('numpy')})
except ImportError:
raise ImportError(
'experimental_lambdify failed to import numpy.')
if use_interval:
namespace.update({'imath': __import__(
'sympy.plotting.intervalmath', fromlist=['intervalmath'])})
namespace.update({'math': __import__('math')})
# Construct the lambda
if self.print_lambda:
print(newexpr)
eval_str = 'lambda %s : ( %s )' % (argstr, newexpr)
self.eval_str = eval_str
exec_("from __future__ import division; MYNEWLAMBDA = %s" % eval_str, namespace)
self.lambda_func = namespace['MYNEWLAMBDA']
def __call__(self, *args, **kwargs):
return self.lambda_func(*args, **kwargs)
##############################################################################
# Dicts for translating from sympy to other modules
##############################################################################
###
# builtins
###
# Functions with different names in builtins
builtin_functions_different = {
'Min': 'min',
'Max': 'max',
'Abs': 'abs',
}
# Strings that should be translated
builtin_not_functions = {
'I': '1j',
# 'oo': '1e400',
}
###
# numpy
###
# Functions that are the same in numpy
numpy_functions_same = [
'sin', 'cos', 'tan', 'sinh', 'cosh', 'tanh', 'exp', 'log',
'sqrt', 'floor', 'conjugate',
]
# Functions with different names in numpy
numpy_functions_different = {
"acos": "arccos",
"acosh": "arccosh",
"arg": "angle",
"asin": "arcsin",
"asinh": "arcsinh",
"atan": "arctan",
"atan2": "arctan2",
"atanh": "arctanh",
"ceiling": "ceil",
"im": "imag",
"ln": "log",
"Max": "amax",
"Min": "amin",
"re": "real",
"Abs": "abs",
}
# Strings that should be translated
numpy_not_functions = {
'pi': 'np.pi',
'oo': 'np.inf',
'E': 'np.e',
}
###
# python math
###
# Functions that are the same in math
math_functions_same = [
'sin', 'cos', 'tan', 'asin', 'acos', 'atan', 'atan2',
'sinh', 'cosh', 'tanh', 'asinh', 'acosh', 'atanh',
'exp', 'log', 'erf', 'sqrt', 'floor', 'factorial', 'gamma',
]
# Functions with different names in math
math_functions_different = {
'ceiling': 'ceil',
'ln': 'log',
'loggamma': 'lgamma'
}
# Strings that should be translated
math_not_functions = {
'pi': 'math.pi',
'E': 'math.e',
}
###
# python cmath
###
# Functions that are the same in cmath
cmath_functions_same = [
'sin', 'cos', 'tan', 'asin', 'acos', 'atan',
'sinh', 'cosh', 'tanh', 'asinh', 'acosh', 'atanh',
'exp', 'log', 'sqrt',
]
# Functions with different names in cmath
cmath_functions_different = {
'ln': 'log',
'arg': 'phase',
}
# Strings that should be translated
cmath_not_functions = {
'pi': 'cmath.pi',
'E': 'cmath.e',
}
###
# intervalmath
###
interval_not_functions = {
'pi': 'math.pi',
'E': 'math.e'
}
interval_functions_same = [
'sin', 'cos', 'exp', 'tan', 'atan', 'log',
'sqrt', 'cosh', 'sinh', 'tanh', 'floor',
'acos', 'asin', 'acosh', 'asinh', 'atanh',
'Abs', 'And', 'Or'
]
interval_functions_different = {
'Min': 'imin',
'Max': 'imax',
'ceiling': 'ceil',
}
###
# mpmath, etc
###
#TODO
###
# Create the final ordered tuples of dictionaries
###
# For strings
def get_dict_str(self):
dict_str = dict(self.builtin_not_functions)
if self.use_np:
dict_str.update(self.numpy_not_functions)
if self.use_python_math:
dict_str.update(self.math_not_functions)
if self.use_python_cmath:
dict_str.update(self.cmath_not_functions)
if self.use_interval:
dict_str.update(self.interval_not_functions)
return dict_str
# For functions
def get_dict_fun(self):
dict_fun = dict(self.builtin_functions_different)
if self.use_np:
for s in self.numpy_functions_same:
dict_fun[s] = 'np.' + s
for k, v in self.numpy_functions_different.items():
dict_fun[k] = 'np.' + v
if self.use_python_math:
for s in self.math_functions_same:
dict_fun[s] = 'math.' + s
for k, v in self.math_functions_different.items():
dict_fun[k] = 'math.' + v
if self.use_python_cmath:
for s in self.cmath_functions_same:
dict_fun[s] = 'cmath.' + s
for k, v in self.cmath_functions_different.items():
dict_fun[k] = 'cmath.' + v
if self.use_interval:
for s in self.interval_functions_same:
dict_fun[s] = 'imath.' + s
for k, v in self.interval_functions_different.items():
dict_fun[k] = 'imath.' + v
return dict_fun
##############################################################################
# The translator functions, tree parsers, etc.
##############################################################################
def str2tree(self, exprstr):
"""Converts an expression string to a tree.
Functions are represented by ('func_name(', tree_of_arguments).
Other expressions are (head_string, mid_tree, tail_str).
Expressions that do not contain functions are directly returned.
Examples
========
>>> from sympy.abc import x, y, z
>>> from sympy import Integral, sin
>>> from sympy.plotting.experimental_lambdify import Lambdifier
>>> str2tree = Lambdifier([x], x).str2tree
>>> str2tree(str(Integral(x, (x, 1, y))))
('', ('Integral(', 'x, (x, 1, y)'), ')')
>>> str2tree(str(x+y))
'x + y'
>>> str2tree(str(x+y*sin(z)+1))
('x + y*', ('sin(', 'z'), ') + 1')
>>> str2tree('sin(y*(y + 1.1) + (sin(y)))')
('', ('sin(', ('y*(y + 1.1) + (', ('sin(', 'y'), '))')), ')')
"""
#matches the first 'function_name('
first_par = re.search(r'(\w+\()', exprstr)
if first_par is None:
return exprstr
else:
start = first_par.start()
end = first_par.end()
head = exprstr[:start]
func = exprstr[start:end]
tail = exprstr[end:]
count = 0
for i, c in enumerate(tail):
if c == '(':
count += 1
elif c == ')':
count -= 1
if count == -1:
break
func_tail = self.str2tree(tail[:i])
tail = self.str2tree(tail[i:])
return (head, (func, func_tail), tail)
@classmethod
def tree2str(cls, tree):
"""Converts a tree to string without translations.
Examples
========
>>> from sympy.abc import x, y, z
>>> from sympy import Integral, sin
>>> from sympy.plotting.experimental_lambdify import Lambdifier
>>> str2tree = Lambdifier([x], x).str2tree
>>> tree2str = Lambdifier([x], x).tree2str
>>> tree2str(str2tree(str(x+y*sin(z)+1)))
'x + y*sin(z) + 1'
"""
if isinstance(tree, str):
return tree
else:
return ''.join(map(cls.tree2str, tree))
def tree2str_translate(self, tree):
"""Converts a tree to string with translations.
Function names are translated by translate_func.
Other strings are translated by translate_str.
"""
if isinstance(tree, str):
return self.translate_str(tree)
elif isinstance(tree, tuple) and len(tree) == 2:
return self.translate_func(tree[0][:-1], tree[1])
else:
return ''.join([self.tree2str_translate(t) for t in tree])
def translate_str(self, estr):
"""Translate substrings of estr using in order the dictionaries in
dict_tuple_str."""
for pattern, repl in self.dict_str.items():
estr = re.sub(pattern, repl, estr)
return estr
def translate_func(self, func_name, argtree):
"""Translate function names and the tree of arguments.
If the function name is not in the dictionaries of dict_tuple_fun then the
function is surrounded by a float((...).evalf()).
The use of float is necessary as np.<function>(sympy.Float(..)) raises an
error."""
if func_name in self.dict_fun:
new_name = self.dict_fun[func_name]
argstr = self.tree2str_translate(argtree)
return new_name + '(' + argstr
else:
template = '(%s(%s)).evalf(' if self.use_evalf else '%s(%s'
if self.float_wrap_evalf:
template = 'float(%s)' % template
elif self.complex_wrap_evalf:
template = 'complex(%s)' % template
# Wrapping should only happen on the outermost expression, which
# is the only thing we know will be a number.
float_wrap_evalf = self.float_wrap_evalf
complex_wrap_evalf = self.complex_wrap_evalf
self.float_wrap_evalf = False
self.complex_wrap_evalf = False
ret = template % (func_name, self.tree2str_translate(argtree))
self.float_wrap_evalf = float_wrap_evalf
self.complex_wrap_evalf = complex_wrap_evalf
return ret
##############################################################################
# The namespace constructors
##############################################################################
@classmethod
def sympy_expression_namespace(cls, expr):
"""Traverses the (func, args) tree of an expression and creates a sympy
namespace. All other modules are imported only as a module name. That way
the namespace is not polluted and rests quite small. It probably causes much
more variable lookups and so it takes more time, but there are no tests on
that for the moment."""
if expr is None:
return {}
else:
funcname = str(expr.func)
# XXX Workaround
# Here we add an ugly workaround because str(func(x))
# is not always the same as str(func). Eg
# >>> str(Integral(x))
# "Integral(x)"
# >>> str(Integral)
# "<class 'sympy.integrals.integrals.Integral'>"
# >>> str(sqrt(x))
# "sqrt(x)"
# >>> str(sqrt)
# "<function sqrt at 0x3d92de8>"
# >>> str(sin(x))
# "sin(x)"
# >>> str(sin)
# "sin"
# Either one of those can be used but not all at the same time.
# The code considers the sin example as the right one.
regexlist = [
r'<class \'sympy[\w.]*?.([\w]*)\'>$',
# the example Integral
r'<function ([\w]*) at 0x[\w]*>$', # the example sqrt
]
for r in regexlist:
m = re.match(r, funcname)
if m is not None:
funcname = m.groups()[0]
# End of the workaround
# XXX debug: print funcname
args_dict = {}
for a in expr.args:
if (isinstance(a, Symbol) or
isinstance(a, NumberSymbol) or
a in [I, zoo, oo]):
continue
else:
args_dict.update(cls.sympy_expression_namespace(a))
args_dict.update({funcname: expr.func})
return args_dict
@staticmethod
def sympy_atoms_namespace(expr):
"""For no real reason this function is separated from
sympy_expression_namespace. It can be moved to it."""
atoms = expr.atoms(Symbol, NumberSymbol, I, zoo, oo)
d = {}
for a in atoms:
# XXX debug: print 'atom:' + str(a)
d[str(a)] = a
return d
|
091aa624654f5af6347e1d941f8c418423424abbed2b1b274d1ba5678c4d5f92
|
from sympy import (
Abs, And, binomial, Catalan, cos, Derivative, E, Eq, exp, EulerGamma,
factorial, Function, harmonic, I, Integral, KroneckerDelta, log,
nan, Ne, Or, oo, pi, Piecewise, Product, product, Rational, S, simplify,
sin, sqrt, Sum, summation, Symbol, symbols, sympify, zeta, gamma, Le,
Indexed, Idx, IndexedBase, prod, Dummy)
from sympy.abc import a, b, c, d, f, k, m, x, y, z
from sympy.concrete.summations import telescopic
from sympy.utilities.pytest import XFAIL, raises
from sympy import simplify
from sympy.matrices import Matrix
from sympy.core.mod import Mod
from sympy.core.compatibility import range
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
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)) == oo
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(Rational(1, 2)**n, (n, 1, oo)) == 1
assert summation(2**n, (n, 0, b)) == 2**(b + 1) - 1
assert summation(2**n, (n, 1, oo)) == 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)) == -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) - S(4)/3
assert summation((-1)**x, (x, 0, n)) == -(-1)**(n + 1)/S(2) + S(1)/2
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)) == 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 == S(1)/3
assert result.is_Float
result = Sum(0.99999**n, (n, 1, oo)).doit()
assert result == 99999
assert result.is_Float
result = Sum(Rational(1, 2)**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 == S(3)/2
assert not result.is_Float
assert Sum(1.0**n, (n, 1, oo)).doit() == oo
assert Sum(2.43**n, (n, 1, oo)).doit() == 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 = Rational(1, 2)*(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
def test_other_sums():
f = m**2 + m*exp(m)
g = 3*exp(S(3)/2)/2 + exp(S(1)/2)/2 - exp(-S(1)/2)/2 - 3*exp(-S(3)/2)/2 + 5
assert summation(f, (m, -S(3)/2, S(3)/2)).expand() == 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 m, n in [(2, 4), (2, 20), (10, 20), (18, 20)]:
A = Sum(1/k**3, (k, 1, oo))
s, e = A.euler_maclaurin(m, n)
assert abs((s - zeta(3)).evalf()) < e.evalf()
raises(ValueError, lambda: Sum(1, (x, 0, 1), (k, 0, 1)).euler_maclaurin())
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 simplify(product(1 + 1/n, (n, a, b))) == (1 + b)/a
assert simplify(product(n + 1, (n, a, b))) == gamma(2 + b)/gamma(1 + a)
assert simplify(product((n + 1)/(n - 1), (n, a, b))) == b*(1 + b)/(a*(a - 1))
assert simplify(product(n/(n + 1)/(n + 2), (n, a, b))) == \
a*gamma(a + 2)/(b + 1)/gamma(b + 3)
assert simplify(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(1)/2)*gamma(b + S(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()
assert Sum(KroneckerDelta(m, n), (m, -oo, oo)).doit() == Piecewise((1, And(-oo < n, n < oo)), (0, True))
assert Sum(x*KroneckerDelta(m, n), (m, -oo, oo)).doit() == Piecewise((x, And(-oo < n, n < oo)), (0, True))
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(S(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(Piecewise((f(n), And(Le(0, n), n < oo)), (0, True)), (n, 1, oo))
l = Symbol('l', integer=True, positive=True)
assert Sum(f(l) * Sum(KroneckerDelta(m, l), (m, 0, oo)), (l, 1, oo)).doit() == \
Sum(f(l), (l, 1, oo))
# issue 2597
nmax = symbols('N', integer=True, positive=True)
pw = Piecewise((1, And(S(1) <= n, n <= nmax)), (0, True))
assert Sum(pw, (n, 1, nmax)).doit() == Sum(pw, (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
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)) == -S(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
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()
def test_issue_4171():
assert summation(factorial(2*k + 1)/factorial(2*k), (k, 0, oo)) == oo
assert summation(2*k + 1, (k, 0, oo)) == 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():
y, t, v = symbols('y, t, v')
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 = symbols('b, v', 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))
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))
def test_issue_4668():
assert summation(1/n, (n, 2, oo)) == oo
def test_matrix_sum():
A = Matrix([[0,1],[n,0]])
assert Sum(A,(n,0,3)).doit() == Matrix([[0, 4], [6, 0]])
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
# 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**(S(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
# 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, -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
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_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():
raises(NotImplementedError, lambda: Sum(sin(n)/log(log(n)), (n, 22, oo)).is_convergent())
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_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)))
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21beda6f39fa68d512c15804aec4f8d37880ca4e8d6693742a8671d0348b09b7
|
from sympy import (symbols, pi, Piecewise, sin, cos, sinc, Rational,
oo, fourier_series, Add)
from sympy.series.fourier import FourierSeries
from sympy.utilities.pytest import raises
from sympy.core.cache import lru_cache
x, y, z = symbols('x y z')
# Don't declare these during import because they are slow
@lru_cache()
def _get_examples():
fo = fourier_series(x, (x, -pi, pi))
fe = fourier_series(x**2, (-pi, pi))
fp = fourier_series(Piecewise((0, x < 0), (pi, True)), (x, -pi, pi))
return fo, fe, fp
def test_FourierSeries():
fo, fe, fp = _get_examples()
assert fourier_series(1, (-pi, pi)) == 1
assert (Piecewise((0, x < 0), (pi, True)).
fourier_series((x, -pi, pi)).truncate()) == fp.truncate()
assert isinstance(fo, FourierSeries)
assert fo.function == x
assert fo.x == x
assert fo.period == (-pi, pi)
assert fo.term(3) == 2*sin(3*x) / 3
assert fe.term(3) == -4*cos(3*x) / 9
assert fp.term(3) == 2*sin(3*x) / 3
assert fo.as_leading_term(x) == 2*sin(x)
assert fe.as_leading_term(x) == pi**2 / 3
assert fp.as_leading_term(x) == pi / 2
assert fo.truncate() == 2*sin(x) - sin(2*x) + (2*sin(3*x) / 3)
assert fe.truncate() == -4*cos(x) + cos(2*x) + pi**2 / 3
assert fp.truncate() == 2*sin(x) + (2*sin(3*x) / 3) + pi / 2
fot = fo.truncate(n=None)
s = [0, 2*sin(x), -sin(2*x)]
for i, t in enumerate(fot):
if i == 3:
break
assert s[i] == t
def _check_iter(f, i):
for ind, t in enumerate(f):
assert t == f[ind]
if ind == i:
break
_check_iter(fo, 3)
_check_iter(fe, 3)
_check_iter(fp, 3)
assert fo.subs(x, x**2) == fo
raises(ValueError, lambda: fourier_series(x, (0, 1, 2)))
raises(ValueError, lambda: fourier_series(x, (x, 0, oo)))
raises(ValueError, lambda: fourier_series(x*y, (0, oo)))
def test_FourierSeries_2():
p = Piecewise((0, x < 0), (x, True))
f = fourier_series(p, (x, -2, 2))
assert f.term(3) == (2*sin(3*pi*x / 2) / (3*pi) -
4*cos(3*pi*x / 2) / (9*pi**2))
assert f.truncate() == (2*sin(pi*x / 2) / pi - sin(pi*x) / pi -
4*cos(pi*x / 2) / pi**2 + Rational(1, 2))
def test_fourier_series_square_wave():
"""Test if fourier_series approximates discontinuous function correctly."""
square_wave = Piecewise((1, x < pi), (-1, True))
s = fourier_series(square_wave, (x, 0, 2*pi))
assert s.truncate(3) == 4 / pi * sin(x) + 4 / (3 * pi) * sin(3 * x) + \
4 / (5 * pi) * sin(5 * x)
assert s.sigma_approximation(4) == 4 / pi * sin(x) * sinc(pi / 4) + \
4 / (3 * pi) * sin(3 * x) * sinc(3 * pi / 4)
def test_FourierSeries__operations():
fo, fe, fp = _get_examples()
fes = fe.scale(-1).shift(pi**2)
assert fes.truncate() == 4*cos(x) - cos(2*x) + 2*pi**2 / 3
assert fp.shift(-pi/2).truncate() == (2*sin(x) + (2*sin(3*x) / 3) +
(2*sin(5*x) / 5))
fos = fo.scale(3)
assert fos.truncate() == 6*sin(x) - 3*sin(2*x) + 2*sin(3*x)
fx = fe.scalex(2).shiftx(1)
assert fx.truncate() == -4*cos(2*x + 2) + cos(4*x + 4) + pi**2 / 3
fl = fe.scalex(3).shift(-pi).scalex(2).shiftx(1).scale(4)
assert fl.truncate() == (-16*cos(6*x + 6) + 4*cos(12*x + 12) -
4*pi + 4*pi**2 / 3)
raises(ValueError, lambda: fo.shift(x))
raises(ValueError, lambda: fo.shiftx(sin(x)))
raises(ValueError, lambda: fo.scale(x*y))
raises(ValueError, lambda: fo.scalex(x**2))
def test_FourierSeries__neg():
fo, fe, fp = _get_examples()
assert (-fo).truncate() == -2*sin(x) + sin(2*x) - (2*sin(3*x) / 3)
assert (-fe).truncate() == +4*cos(x) - cos(2*x) - pi**2 / 3
def test_FourierSeries__add__sub():
fo, fe, fp = _get_examples()
assert fo + fo == fo.scale(2)
assert fo - fo == 0
assert -fe - fe == fe.scale(-2)
assert (fo + fe).truncate() == 2*sin(x) - sin(2*x) - 4*cos(x) + cos(2*x) \
+ pi**2 / 3
assert (fo - fe).truncate() == 2*sin(x) - sin(2*x) + 4*cos(x) - cos(2*x) \
- pi**2 / 3
assert isinstance(fo + 1, Add)
raises(ValueError, lambda: fo + fourier_series(x, (x, 0, 2)))
|
20826831ccb9612f36c00519104f9ded1380c0d12773d7036b822b2121f35238
|
from sympy import (
symbols, sin, simplify, cos, trigsimp, rad, tan, exptrigsimp,sinh,
cosh, diff, cot, Subs, exp, tanh, exp, S, integrate, I,Matrix,
Symbol, coth, pi, log, count_ops, sqrt, E, expand, Piecewise , Rational
)
from sympy.core.compatibility import long
from sympy.utilities.pytest import XFAIL
from sympy.abc import x, y
def test_trigsimp1():
x, y = symbols('x,y')
assert trigsimp(1 - sin(x)**2) == cos(x)**2
assert trigsimp(1 - cos(x)**2) == sin(x)**2
assert trigsimp(sin(x)**2 + cos(x)**2) == 1
assert trigsimp(1 + tan(x)**2) == 1/cos(x)**2
assert trigsimp(1/cos(x)**2 - 1) == tan(x)**2
assert trigsimp(1/cos(x)**2 - tan(x)**2) == 1
assert trigsimp(1 + cot(x)**2) == 1/sin(x)**2
assert trigsimp(1/sin(x)**2 - 1) == 1/tan(x)**2
assert trigsimp(1/sin(x)**2 - cot(x)**2) == 1
assert trigsimp(5*cos(x)**2 + 5*sin(x)**2) == 5
assert trigsimp(5*cos(x/2)**2 + 2*sin(x/2)**2) == 3*cos(x)/2 + S(7)/2
assert trigsimp(sin(x)/cos(x)) == tan(x)
assert trigsimp(2*tan(x)*cos(x)) == 2*sin(x)
assert trigsimp(cot(x)**3*sin(x)**3) == cos(x)**3
assert trigsimp(y*tan(x)**2/sin(x)**2) == y/cos(x)**2
assert trigsimp(cot(x)/cos(x)) == 1/sin(x)
assert trigsimp(sin(x + y) + sin(x - y)) == 2*sin(x)*cos(y)
assert trigsimp(sin(x + y) - sin(x - y)) == 2*sin(y)*cos(x)
assert trigsimp(cos(x + y) + cos(x - y)) == 2*cos(x)*cos(y)
assert trigsimp(cos(x + y) - cos(x - y)) == -2*sin(x)*sin(y)
assert trigsimp(tan(x + y) - tan(x)/(1 - tan(x)*tan(y))) == \
sin(y)/(-sin(y)*tan(x) + cos(y)) # -tan(y)/(tan(x)*tan(y) - 1)
assert trigsimp(sinh(x + y) + sinh(x - y)) == 2*sinh(x)*cosh(y)
assert trigsimp(sinh(x + y) - sinh(x - y)) == 2*sinh(y)*cosh(x)
assert trigsimp(cosh(x + y) + cosh(x - y)) == 2*cosh(x)*cosh(y)
assert trigsimp(cosh(x + y) - cosh(x - y)) == 2*sinh(x)*sinh(y)
assert trigsimp(tanh(x + y) - tanh(x)/(1 + tanh(x)*tanh(y))) == \
sinh(y)/(sinh(y)*tanh(x) + cosh(y))
assert trigsimp(cos(0.12345)**2 + sin(0.12345)**2) == 1
e = 2*sin(x)**2 + 2*cos(x)**2
assert trigsimp(log(e)) == log(2)
def test_trigsimp1a():
assert trigsimp(sin(2)**2*cos(3)*exp(2)/cos(2)**2) == tan(2)**2*cos(3)*exp(2)
assert trigsimp(tan(2)**2*cos(3)*exp(2)*cos(2)**2) == sin(2)**2*cos(3)*exp(2)
assert trigsimp(cot(2)*cos(3)*exp(2)*sin(2)) == cos(3)*exp(2)*cos(2)
assert trigsimp(tan(2)*cos(3)*exp(2)/sin(2)) == cos(3)*exp(2)/cos(2)
assert trigsimp(cot(2)*cos(3)*exp(2)/cos(2)) == cos(3)*exp(2)/sin(2)
assert trigsimp(cot(2)*cos(3)*exp(2)*tan(2)) == cos(3)*exp(2)
assert trigsimp(sinh(2)*cos(3)*exp(2)/cosh(2)) == tanh(2)*cos(3)*exp(2)
assert trigsimp(tanh(2)*cos(3)*exp(2)*cosh(2)) == sinh(2)*cos(3)*exp(2)
assert trigsimp(coth(2)*cos(3)*exp(2)*sinh(2)) == cosh(2)*cos(3)*exp(2)
assert trigsimp(tanh(2)*cos(3)*exp(2)/sinh(2)) == cos(3)*exp(2)/cosh(2)
assert trigsimp(coth(2)*cos(3)*exp(2)/cosh(2)) == cos(3)*exp(2)/sinh(2)
assert trigsimp(coth(2)*cos(3)*exp(2)*tanh(2)) == cos(3)*exp(2)
def test_trigsimp2():
x, y = symbols('x,y')
assert trigsimp(cos(x)**2*sin(y)**2 + cos(x)**2*cos(y)**2 + sin(x)**2,
recursive=True) == 1
assert trigsimp(sin(x)**2*sin(y)**2 + sin(x)**2*cos(y)**2 + cos(x)**2,
recursive=True) == 1
assert trigsimp(
Subs(x, x, sin(y)**2 + cos(y)**2)) == Subs(x, x, 1)
def test_issue_4373():
x = Symbol("x")
assert abs(trigsimp(2.0*sin(x)**2 + 2.0*cos(x)**2) - 2.0) < 1e-10
def test_trigsimp3():
x, y = symbols('x,y')
assert trigsimp(sin(x)/cos(x)) == tan(x)
assert trigsimp(sin(x)**2/cos(x)**2) == tan(x)**2
assert trigsimp(sin(x)**3/cos(x)**3) == tan(x)**3
assert trigsimp(sin(x)**10/cos(x)**10) == tan(x)**10
assert trigsimp(cos(x)/sin(x)) == 1/tan(x)
assert trigsimp(cos(x)**2/sin(x)**2) == 1/tan(x)**2
assert trigsimp(cos(x)**10/sin(x)**10) == 1/tan(x)**10
assert trigsimp(tan(x)) == trigsimp(sin(x)/cos(x))
def test_issue_4661():
a, x, y = symbols('a x y')
eq = -4*sin(x)**4 + 4*cos(x)**4 - 8*cos(x)**2
assert trigsimp(eq) == -4
n = sin(x)**6 + 4*sin(x)**4*cos(x)**2 + 5*sin(x)**2*cos(x)**4 + 2*cos(x)**6
d = -sin(x)**2 - 2*cos(x)**2
assert simplify(n/d) == -1
assert trigsimp(-2*cos(x)**2 + cos(x)**4 - sin(x)**4) == -1
eq = (- sin(x)**3/4)*cos(x) + (cos(x)**3/4)*sin(x) - sin(2*x)*cos(2*x)/8
assert trigsimp(eq) == 0
def test_issue_4494():
a, b = symbols('a b')
eq = sin(a)**2*sin(b)**2 + cos(a)**2*cos(b)**2*tan(a)**2 + cos(a)**2
assert trigsimp(eq) == 1
def test_issue_5948():
a, x, y = symbols('a x y')
assert trigsimp(diff(integrate(cos(x)/sin(x)**7, x), x)) == \
cos(x)/sin(x)**7
def test_issue_4775():
a, x, y = symbols('a x y')
assert trigsimp(sin(x)*cos(y)+cos(x)*sin(y)) == sin(x + y)
assert trigsimp(sin(x)*cos(y)+cos(x)*sin(y)+3) == sin(x + y) + 3
def test_issue_4280():
a, x, y = symbols('a x y')
assert trigsimp(cos(x)**2 + cos(y)**2*sin(x)**2 + sin(y)**2*sin(x)**2) == 1
assert trigsimp(a**2*sin(x)**2 + a**2*cos(y)**2*cos(x)**2 + a**2*cos(x)**2*sin(y)**2) == a**2
assert trigsimp(a**2*cos(y)**2*sin(x)**2 + a**2*sin(y)**2*sin(x)**2) == a**2*sin(x)**2
def test_issue_3210():
eqs = (sin(2)*cos(3) + sin(3)*cos(2),
-sin(2)*sin(3) + cos(2)*cos(3),
sin(2)*cos(3) - sin(3)*cos(2),
sin(2)*sin(3) + cos(2)*cos(3),
sin(2)*sin(3) + cos(2)*cos(3) + cos(2),
sinh(2)*cosh(3) + sinh(3)*cosh(2),
sinh(2)*sinh(3) + cosh(2)*cosh(3),
)
assert [trigsimp(e) for e in eqs] == [
sin(5),
cos(5),
-sin(1),
cos(1),
cos(1) + cos(2),
sinh(5),
cosh(5),
]
def test_trigsimp_issues():
a, x, y = symbols('a x y')
# issue 4625 - factor_terms works, too
assert trigsimp(sin(x)**3 + cos(x)**2*sin(x)) == sin(x)
# issue 5948
assert trigsimp(diff(integrate(cos(x)/sin(x)**3, x), x)) == \
cos(x)/sin(x)**3
assert trigsimp(diff(integrate(sin(x)/cos(x)**3, x), x)) == \
sin(x)/cos(x)**3
# check integer exponents
e = sin(x)**y/cos(x)**y
assert trigsimp(e) == e
assert trigsimp(e.subs(y, 2)) == tan(x)**2
assert trigsimp(e.subs(x, 1)) == tan(1)**y
# check for multiple patterns
assert (cos(x)**2/sin(x)**2*cos(y)**2/sin(y)**2).trigsimp() == \
1/tan(x)**2/tan(y)**2
assert trigsimp(cos(x)/sin(x)*cos(x+y)/sin(x+y)) == \
1/(tan(x)*tan(x + y))
eq = cos(2)*(cos(3) + 1)**2/(cos(3) - 1)**2
assert trigsimp(eq) == eq.factor() # factor makes denom (-1 + cos(3))**2
assert trigsimp(cos(2)*(cos(3) + 1)**2*(cos(3) - 1)**2) == \
cos(2)*sin(3)**4
# issue 6789; this generates an expression that formerly caused
# trigsimp to hang
assert cot(x).equals(tan(x)) is False
# nan or the unchanged expression is ok, but not sin(1)
z = cos(x)**2 + sin(x)**2 - 1
z1 = tan(x)**2 - 1/cot(x)**2
n = (1 + z1/z)
assert trigsimp(sin(n)) != sin(1)
eq = x*(n - 1) - x*n
assert trigsimp(eq) is S.NaN
assert trigsimp(eq, recursive=True) is S.NaN
assert trigsimp(1).is_Integer
assert trigsimp(-sin(x)**4 - 2*sin(x)**2*cos(x)**2 - cos(x)**4) == -1
def test_trigsimp_issue_2515():
x = Symbol('x')
assert trigsimp(x*cos(x)*tan(x)) == x*sin(x)
assert trigsimp(-sin(x) + cos(x)*tan(x)) == 0
def test_trigsimp_issue_3826():
assert trigsimp(tan(2*x).expand(trig=True)) == tan(2*x)
def test_trigsimp_issue_4032():
n = Symbol('n', integer=True, positive=True)
assert trigsimp(2**(n/2)*cos(pi*n/4)/2 + 2**(n - 1)/2) == \
2**(n/2)*cos(pi*n/4)/2 + 2**n/4
def test_trigsimp_issue_7761():
assert trigsimp(cosh(pi/4)) == cosh(pi/4)
def test_trigsimp_noncommutative():
x, y = symbols('x,y')
A, B = symbols('A,B', commutative=False)
assert trigsimp(A - A*sin(x)**2) == A*cos(x)**2
assert trigsimp(A - A*cos(x)**2) == A*sin(x)**2
assert trigsimp(A*sin(x)**2 + A*cos(x)**2) == A
assert trigsimp(A + A*tan(x)**2) == A/cos(x)**2
assert trigsimp(A/cos(x)**2 - A) == A*tan(x)**2
assert trigsimp(A/cos(x)**2 - A*tan(x)**2) == A
assert trigsimp(A + A*cot(x)**2) == A/sin(x)**2
assert trigsimp(A/sin(x)**2 - A) == A/tan(x)**2
assert trigsimp(A/sin(x)**2 - A*cot(x)**2) == A
assert trigsimp(y*A*cos(x)**2 + y*A*sin(x)**2) == y*A
assert trigsimp(A*sin(x)/cos(x)) == A*tan(x)
assert trigsimp(A*tan(x)*cos(x)) == A*sin(x)
assert trigsimp(A*cot(x)**3*sin(x)**3) == A*cos(x)**3
assert trigsimp(y*A*tan(x)**2/sin(x)**2) == y*A/cos(x)**2
assert trigsimp(A*cot(x)/cos(x)) == A/sin(x)
assert trigsimp(A*sin(x + y) + A*sin(x - y)) == 2*A*sin(x)*cos(y)
assert trigsimp(A*sin(x + y) - A*sin(x - y)) == 2*A*sin(y)*cos(x)
assert trigsimp(A*cos(x + y) + A*cos(x - y)) == 2*A*cos(x)*cos(y)
assert trigsimp(A*cos(x + y) - A*cos(x - y)) == -2*A*sin(x)*sin(y)
assert trigsimp(A*sinh(x + y) + A*sinh(x - y)) == 2*A*sinh(x)*cosh(y)
assert trigsimp(A*sinh(x + y) - A*sinh(x - y)) == 2*A*sinh(y)*cosh(x)
assert trigsimp(A*cosh(x + y) + A*cosh(x - y)) == 2*A*cosh(x)*cosh(y)
assert trigsimp(A*cosh(x + y) - A*cosh(x - y)) == 2*A*sinh(x)*sinh(y)
assert trigsimp(A*cos(0.12345)**2 + A*sin(0.12345)**2) == 1.0*A
def test_hyperbolic_simp():
x, y = symbols('x,y')
assert trigsimp(sinh(x)**2 + 1) == cosh(x)**2
assert trigsimp(cosh(x)**2 - 1) == sinh(x)**2
assert trigsimp(cosh(x)**2 - sinh(x)**2) == 1
assert trigsimp(1 - tanh(x)**2) == 1/cosh(x)**2
assert trigsimp(1 - 1/cosh(x)**2) == tanh(x)**2
assert trigsimp(tanh(x)**2 + 1/cosh(x)**2) == 1
assert trigsimp(coth(x)**2 - 1) == 1/sinh(x)**2
assert trigsimp(1/sinh(x)**2 + 1) == 1/tanh(x)**2
assert trigsimp(coth(x)**2 - 1/sinh(x)**2) == 1
assert trigsimp(5*cosh(x)**2 - 5*sinh(x)**2) == 5
assert trigsimp(5*cosh(x/2)**2 - 2*sinh(x/2)**2) == 3*cosh(x)/2 + S(7)/2
assert trigsimp(sinh(x)/cosh(x)) == tanh(x)
assert trigsimp(tanh(x)) == trigsimp(sinh(x)/cosh(x))
assert trigsimp(cosh(x)/sinh(x)) == 1/tanh(x)
assert trigsimp(2*tanh(x)*cosh(x)) == 2*sinh(x)
assert trigsimp(coth(x)**3*sinh(x)**3) == cosh(x)**3
assert trigsimp(y*tanh(x)**2/sinh(x)**2) == y/cosh(x)**2
assert trigsimp(coth(x)/cosh(x)) == 1/sinh(x)
for a in (pi/6*I, pi/4*I, pi/3*I):
assert trigsimp(sinh(a)*cosh(x) + cosh(a)*sinh(x)) == sinh(x + a)
assert trigsimp(-sinh(a)*cosh(x) + cosh(a)*sinh(x)) == sinh(x - a)
e = 2*cosh(x)**2 - 2*sinh(x)**2
assert trigsimp(log(e)) == log(2)
assert trigsimp(cosh(x)**2*cosh(y)**2 - cosh(x)**2*sinh(y)**2 - sinh(x)**2,
recursive=True) == 1
assert trigsimp(sinh(x)**2*sinh(y)**2 - sinh(x)**2*cosh(y)**2 + cosh(x)**2,
recursive=True) == 1
assert abs(trigsimp(2.0*cosh(x)**2 - 2.0*sinh(x)**2) - 2.0) < 1e-10
assert trigsimp(sinh(x)**2/cosh(x)**2) == tanh(x)**2
assert trigsimp(sinh(x)**3/cosh(x)**3) == tanh(x)**3
assert trigsimp(sinh(x)**10/cosh(x)**10) == tanh(x)**10
assert trigsimp(cosh(x)**3/sinh(x)**3) == 1/tanh(x)**3
assert trigsimp(cosh(x)/sinh(x)) == 1/tanh(x)
assert trigsimp(cosh(x)**2/sinh(x)**2) == 1/tanh(x)**2
assert trigsimp(cosh(x)**10/sinh(x)**10) == 1/tanh(x)**10
assert trigsimp(x*cosh(x)*tanh(x)) == x*sinh(x)
assert trigsimp(-sinh(x) + cosh(x)*tanh(x)) == 0
assert tan(x) != 1/cot(x) # cot doesn't auto-simplify
assert trigsimp(tan(x) - 1/cot(x)) == 0
assert trigsimp(3*tanh(x)**7 - 2/coth(x)**7) == tanh(x)**7
def test_trigsimp_groebner():
from sympy.simplify.trigsimp import trigsimp_groebner
c = cos(x)
s = sin(x)
ex = (4*s*c + 12*s + 5*c**3 + 21*c**2 + 23*c + 15)/(
-s*c**2 + 2*s*c + 15*s + 7*c**3 + 31*c**2 + 37*c + 21)
resnum = (5*s - 5*c + 1)
resdenom = (8*s - 6*c)
results = [resnum/resdenom, (-resnum)/(-resdenom)]
assert trigsimp_groebner(ex) in results
assert trigsimp_groebner(s/c, hints=[tan]) == tan(x)
assert trigsimp_groebner(c*s) == c*s
assert trigsimp((-s + 1)/c + c/(-s + 1),
method='groebner') == 2/c
assert trigsimp((-s + 1)/c + c/(-s + 1),
method='groebner', polynomial=True) == 2/c
# Test quick=False works
assert trigsimp_groebner(ex, hints=[2]) in results
assert trigsimp_groebner(ex, hints=[long(2)]) in results
# test "I"
assert trigsimp_groebner(sin(I*x)/cos(I*x), hints=[tanh]) == I*tanh(x)
# test hyperbolic / sums
assert trigsimp_groebner((tanh(x)+tanh(y))/(1+tanh(x)*tanh(y)),
hints=[(tanh, x, y)]) == tanh(x + y)
def test_issue_2827_trigsimp_methods():
measure1 = lambda expr: len(str(expr))
measure2 = lambda expr: -count_ops(expr)
# Return the most complicated result
expr = (x + 1)/(x + sin(x)**2 + cos(x)**2)
ans = Matrix([1])
M = Matrix([expr])
assert trigsimp(M, method='fu', measure=measure1) == ans
assert trigsimp(M, method='fu', measure=measure2) != ans
# all methods should work with Basic expressions even if they
# aren't Expr
M = Matrix.eye(1)
assert all(trigsimp(M, method=m) == M for m in
'fu matching groebner old'.split())
# watch for E in exptrigsimp, not only exp()
eq = 1/sqrt(E) + E
assert exptrigsimp(eq) == eq
def test_issue_15129_trigsimp_methods():
t1 = Matrix([sin(Rational(1, 50)), cos(Rational(1, 50)), 0])
t2 = Matrix([sin(Rational(1, 25)), cos(Rational(1, 25)), 0])
t3 = Matrix([cos(Rational(1, 25)), sin(Rational(1, 25)), 0])
r1 = t1.dot(t2)
r2 = t1.dot(t3)
assert trigsimp(r1) == cos(S(1)/50)
assert trigsimp(r2) == sin(S(3)/50)
def test_exptrigsimp():
def valid(a, b):
from sympy.utilities.randtest import verify_numerically as tn
if not (tn(a, b) and a == b):
return False
return True
assert exptrigsimp(exp(x) + exp(-x)) == 2*cosh(x)
assert exptrigsimp(exp(x) - exp(-x)) == 2*sinh(x)
assert exptrigsimp((2*exp(x)-2*exp(-x))/(exp(x)+exp(-x))) == 2*tanh(x)
assert exptrigsimp((2*exp(2*x)-2)/(exp(2*x)+1)) == 2*tanh(x)
e = [cos(x) + I*sin(x), cos(x) - I*sin(x),
cosh(x) - sinh(x), cosh(x) + sinh(x)]
ok = [exp(I*x), exp(-I*x), exp(-x), exp(x)]
assert all(valid(i, j) for i, j in zip(
[exptrigsimp(ei) for ei in e], ok))
ue = [cos(x) + sin(x), cos(x) - sin(x),
cosh(x) + I*sinh(x), cosh(x) - I*sinh(x)]
assert [exptrigsimp(ei) == ei for ei in ue]
res = []
ok = [y*tanh(1), 1/(y*tanh(1)), I*y*tan(1), -I/(y*tan(1)),
y*tanh(x), 1/(y*tanh(x)), I*y*tan(x), -I/(y*tan(x)),
y*tanh(1 + I), 1/(y*tanh(1 + I))]
for a in (1, I, x, I*x, 1 + I):
w = exp(a)
eq = y*(w - 1/w)/(w + 1/w)
res.append(simplify(eq))
res.append(simplify(1/eq))
assert all(valid(i, j) for i, j in zip(res, ok))
for a in range(1, 3):
w = exp(a)
e = w + 1/w
s = simplify(e)
assert s == exptrigsimp(e)
assert valid(s, 2*cosh(a))
e = w - 1/w
s = simplify(e)
assert s == exptrigsimp(e)
assert valid(s, 2*sinh(a))
def test_exptrigsimp_noncommutative():
a,b = symbols('a b', commutative=False)
x = Symbol('x', commutative=True)
assert exp(a + x) == exptrigsimp(exp(a)*exp(x))
p = exp(a)*exp(b) - exp(b)*exp(a)
assert p == exptrigsimp(p) != 0
def test_powsimp_on_numbers():
assert 2**(S(1)/3 - 2) == 2**(S(1)/3)/4
@XFAIL
def test_issue_6811_fail():
# from doc/src/modules/physics/mechanics/examples.rst, the current `eq`
# at Line 576 (in different variables) was formerly the equivalent and
# shorter expression given below...it would be nice to get the short one
# back again
xp, y, x, z = symbols('xp, y, x, z')
eq = 4*(-19*sin(x)*y + 5*sin(3*x)*y + 15*cos(2*x)*z - 21*z)*xp/(9*cos(x) - 5*cos(3*x))
assert trigsimp(eq) == -2*(2*cos(x)*tan(x)*y + 3*z)*xp/cos(x)
def test_Piecewise():
e1 = x*(x + y) - y*(x + y)
e2 = sin(x)**2 + cos(x)**2
e3 = expand((x + y)*y/x)
s1 = simplify(e1)
s2 = simplify(e2)
s3 = simplify(e3)
# trigsimp tries not to touch non-trig containing args
assert trigsimp(Piecewise((e1, e3 < e2), (e3, True))) == \
Piecewise((e1, e3 < s2), (e3, True))
def test_trigsimp_old():
x, y = symbols('x,y')
assert trigsimp(1 - sin(x)**2, old=True) == cos(x)**2
assert trigsimp(1 - cos(x)**2, old=True) == sin(x)**2
assert trigsimp(sin(x)**2 + cos(x)**2, old=True) == 1
assert trigsimp(1 + tan(x)**2, old=True) == 1/cos(x)**2
assert trigsimp(1/cos(x)**2 - 1, old=True) == tan(x)**2
assert trigsimp(1/cos(x)**2 - tan(x)**2, old=True) == 1
assert trigsimp(1 + cot(x)**2, old=True) == 1/sin(x)**2
assert trigsimp(1/sin(x)**2 - cot(x)**2, old=True) == 1
assert trigsimp(5*cos(x)**2 + 5*sin(x)**2, old=True) == 5
assert trigsimp(sin(x)/cos(x), old=True) == tan(x)
assert trigsimp(2*tan(x)*cos(x), old=True) == 2*sin(x)
assert trigsimp(cot(x)**3*sin(x)**3, old=True) == cos(x)**3
assert trigsimp(y*tan(x)**2/sin(x)**2, old=True) == y/cos(x)**2
assert trigsimp(cot(x)/cos(x), old=True) == 1/sin(x)
assert trigsimp(sin(x + y) + sin(x - y), old=True) == 2*sin(x)*cos(y)
assert trigsimp(sin(x + y) - sin(x - y), old=True) == 2*sin(y)*cos(x)
assert trigsimp(cos(x + y) + cos(x - y), old=True) == 2*cos(x)*cos(y)
assert trigsimp(cos(x + y) - cos(x - y), old=True) == -2*sin(x)*sin(y)
assert trigsimp(sinh(x + y) + sinh(x - y), old=True) == 2*sinh(x)*cosh(y)
assert trigsimp(sinh(x + y) - sinh(x - y), old=True) == 2*sinh(y)*cosh(x)
assert trigsimp(cosh(x + y) + cosh(x - y), old=True) == 2*cosh(x)*cosh(y)
assert trigsimp(cosh(x + y) - cosh(x - y), old=True) == 2*sinh(x)*sinh(y)
assert trigsimp(cos(0.12345)**2 + sin(0.12345)**2, old=True) == 1
assert trigsimp(sin(x)/cos(x), old=True, method='combined') == tan(x)
assert trigsimp(sin(x)/cos(x), old=True, method='groebner') == sin(x)/cos(x)
assert trigsimp(sin(x)/cos(x), old=True, method='groebner', hints=[tan]) == tan(x)
assert trigsimp(1-sin(sin(x)**2+cos(x)**2)**2, old=True, deep=True) == cos(1)**2
|
b6f3823e6dd5b50a6dd5af871ae07e68d6a634625963eb2574fa19aeab718369
|
from sympy import Q, ask, Symbol
from sympy.matrices.expressions import (MatrixSymbol, Identity, ZeroMatrix,
Trace, MatrixSlice, Determinant)
from sympy.matrices.expressions.factorizations import LofLU
from sympy.utilities.pytest import XFAIL
X = MatrixSymbol('X', 2, 2)
Y = MatrixSymbol('Y', 2, 3)
Z = MatrixSymbol('Z', 2, 2)
A1x1 = MatrixSymbol('A1x1', 1, 1)
B1x1 = MatrixSymbol('B1x1', 1, 1)
C0x0 = MatrixSymbol('C0x0', 0, 0)
V1 = MatrixSymbol('V1', 2, 1)
V2 = MatrixSymbol('V2', 2, 1)
def test_square():
assert ask(Q.square(X))
assert not ask(Q.square(Y))
assert ask(Q.square(Y*Y.T))
def test_invertible():
assert ask(Q.invertible(X), Q.invertible(X))
assert ask(Q.invertible(Y)) is False
assert ask(Q.invertible(X*Y), Q.invertible(X)) is False
assert ask(Q.invertible(X*Z), Q.invertible(X)) is None
assert ask(Q.invertible(X*Z), Q.invertible(X) & Q.invertible(Z)) is True
assert ask(Q.invertible(X.T)) is None
assert ask(Q.invertible(X.T), Q.invertible(X)) is True
assert ask(Q.invertible(X.I)) is True
assert ask(Q.invertible(Identity(3))) is True
assert ask(Q.invertible(ZeroMatrix(3, 3))) is False
assert ask(Q.invertible(X), Q.fullrank(X) & Q.square(X))
def test_singular():
assert ask(Q.singular(X)) is None
assert ask(Q.singular(X), Q.invertible(X)) is False
assert ask(Q.singular(X), ~Q.invertible(X)) is True
@XFAIL
def test_invertible_fullrank():
assert ask(Q.invertible(X), Q.fullrank(X)) is True
def test_symmetric():
assert ask(Q.symmetric(X), Q.symmetric(X))
assert ask(Q.symmetric(X*Z), Q.symmetric(X)) is None
assert ask(Q.symmetric(X*Z), Q.symmetric(X) & Q.symmetric(Z)) is True
assert ask(Q.symmetric(X + Z), Q.symmetric(X) & Q.symmetric(Z)) is True
assert ask(Q.symmetric(Y)) is False
assert ask(Q.symmetric(Y*Y.T)) is True
assert ask(Q.symmetric(Y.T*X*Y)) is None
assert ask(Q.symmetric(Y.T*X*Y), Q.symmetric(X)) is True
assert ask(Q.symmetric(X**10), Q.symmetric(X)) is True
assert ask(Q.symmetric(A1x1)) is True
assert ask(Q.symmetric(A1x1 + B1x1)) is True
assert ask(Q.symmetric(A1x1 * B1x1)) is True
assert ask(Q.symmetric(V1.T*V1)) is True
assert ask(Q.symmetric(V1.T*(V1 + V2))) is True
assert ask(Q.symmetric(V1.T*(V1 + V2) + A1x1)) is True
assert ask(Q.symmetric(MatrixSlice(Y, (0, 1), (1, 2)))) is True
def _test_orthogonal_unitary(predicate):
assert ask(predicate(X), predicate(X))
assert ask(predicate(X.T), predicate(X)) is True
assert ask(predicate(X.I), predicate(X)) is True
assert ask(predicate(X**2), predicate(X))
assert ask(predicate(Y)) is False
assert ask(predicate(X)) is None
assert ask(predicate(X), ~Q.invertible(X)) is False
assert ask(predicate(X*Z*X), predicate(X) & predicate(Z)) is True
assert ask(predicate(Identity(3))) is True
assert ask(predicate(ZeroMatrix(3, 3))) is False
assert ask(Q.invertible(X), predicate(X))
assert not ask(predicate(X + Z), predicate(X) & predicate(Z))
def test_orthogonal():
_test_orthogonal_unitary(Q.orthogonal)
def test_unitary():
_test_orthogonal_unitary(Q.unitary)
assert ask(Q.unitary(X), Q.orthogonal(X))
def test_fullrank():
assert ask(Q.fullrank(X), Q.fullrank(X))
assert ask(Q.fullrank(X**2), Q.fullrank(X))
assert ask(Q.fullrank(X.T), Q.fullrank(X)) is True
assert ask(Q.fullrank(X)) is None
assert ask(Q.fullrank(Y)) is None
assert ask(Q.fullrank(X*Z), Q.fullrank(X) & Q.fullrank(Z)) is True
assert ask(Q.fullrank(Identity(3))) is True
assert ask(Q.fullrank(ZeroMatrix(3, 3))) is False
assert ask(Q.invertible(X), ~Q.fullrank(X)) == False
def test_positive_definite():
assert ask(Q.positive_definite(X), Q.positive_definite(X))
assert ask(Q.positive_definite(X.T), Q.positive_definite(X)) is True
assert ask(Q.positive_definite(X.I), Q.positive_definite(X)) is True
assert ask(Q.positive_definite(Y)) is False
assert ask(Q.positive_definite(X)) is None
assert ask(Q.positive_definite(X**3), Q.positive_definite(X))
assert ask(Q.positive_definite(X*Z*X),
Q.positive_definite(X) & Q.positive_definite(Z)) is True
assert ask(Q.positive_definite(X), Q.orthogonal(X))
assert ask(Q.positive_definite(Y.T*X*Y),
Q.positive_definite(X) & Q.fullrank(Y)) is True
assert not ask(Q.positive_definite(Y.T*X*Y), Q.positive_definite(X))
assert ask(Q.positive_definite(Identity(3))) is True
assert ask(Q.positive_definite(ZeroMatrix(3, 3))) is False
assert ask(Q.positive_definite(X + Z), Q.positive_definite(X) &
Q.positive_definite(Z)) is True
assert not ask(Q.positive_definite(-X), Q.positive_definite(X))
assert ask(Q.positive(X[1, 1]), Q.positive_definite(X))
def test_triangular():
assert ask(Q.upper_triangular(X + Z.T + Identity(2)), Q.upper_triangular(X) &
Q.lower_triangular(Z)) is True
assert ask(Q.upper_triangular(X*Z.T), Q.upper_triangular(X) &
Q.lower_triangular(Z)) is True
assert ask(Q.lower_triangular(Identity(3))) is True
assert ask(Q.lower_triangular(ZeroMatrix(3, 3))) is True
assert ask(Q.triangular(X), Q.unit_triangular(X))
assert ask(Q.upper_triangular(X**3), Q.upper_triangular(X))
assert ask(Q.lower_triangular(X**3), Q.lower_triangular(X))
def test_diagonal():
assert ask(Q.diagonal(X + Z.T + Identity(2)), Q.diagonal(X) &
Q.diagonal(Z)) is True
assert ask(Q.diagonal(ZeroMatrix(3, 3)))
assert ask(Q.lower_triangular(X) & Q.upper_triangular(X), Q.diagonal(X))
assert ask(Q.diagonal(X), Q.lower_triangular(X) & Q.upper_triangular(X))
assert ask(Q.symmetric(X), Q.diagonal(X))
assert ask(Q.triangular(X), Q.diagonal(X))
assert ask(Q.diagonal(C0x0))
assert ask(Q.diagonal(A1x1))
assert ask(Q.diagonal(A1x1 + B1x1))
assert ask(Q.diagonal(A1x1*B1x1))
assert ask(Q.diagonal(V1.T*V2))
assert ask(Q.diagonal(V1.T*(X + Z)*V1))
assert ask(Q.diagonal(MatrixSlice(Y, (0, 1), (1, 2)))) is True
assert ask(Q.diagonal(V1.T*(V1 + V2))) is True
assert ask(Q.diagonal(X**3), Q.diagonal(X))
def test_non_atoms():
assert ask(Q.real(Trace(X)), Q.positive(Trace(X)))
@XFAIL
def test_non_trivial_implies():
X = MatrixSymbol('X', 3, 3)
Y = MatrixSymbol('Y', 3, 3)
assert ask(Q.lower_triangular(X+Y), Q.lower_triangular(X) &
Q.lower_triangular(Y)) is True
assert ask(Q.triangular(X), Q.lower_triangular(X)) is True
assert ask(Q.triangular(X+Y), Q.lower_triangular(X) &
Q.lower_triangular(Y)) is True
def test_MatrixSlice():
X = MatrixSymbol('X', 4, 4)
B = MatrixSlice(X, (1, 3), (1, 3))
C = MatrixSlice(X, (0, 3), (1, 3))
assert ask(Q.symmetric(B), Q.symmetric(X))
assert ask(Q.invertible(B), Q.invertible(X))
assert ask(Q.diagonal(B), Q.diagonal(X))
assert ask(Q.orthogonal(B), Q.orthogonal(X))
assert ask(Q.upper_triangular(B), Q.upper_triangular(X))
assert not ask(Q.symmetric(C), Q.symmetric(X))
assert not ask(Q.invertible(C), Q.invertible(X))
assert not ask(Q.diagonal(C), Q.diagonal(X))
assert not ask(Q.orthogonal(C), Q.orthogonal(X))
assert not ask(Q.upper_triangular(C), Q.upper_triangular(X))
def test_det_trace_positive():
X = MatrixSymbol('X', 4, 4)
assert ask(Q.positive(Trace(X)), Q.positive_definite(X))
assert ask(Q.positive(Determinant(X)), Q.positive_definite(X))
def test_field_assumptions():
X = MatrixSymbol('X', 4, 4)
Y = MatrixSymbol('Y', 4, 4)
assert ask(Q.real_elements(X), Q.real_elements(X))
assert not ask(Q.integer_elements(X), Q.real_elements(X))
assert ask(Q.complex_elements(X), Q.real_elements(X))
assert ask(Q.complex_elements(X**2), Q.real_elements(X))
assert ask(Q.real_elements(X**2), Q.integer_elements(X))
assert ask(Q.real_elements(X+Y), Q.real_elements(X)) is None
assert ask(Q.real_elements(X+Y), Q.real_elements(X) & Q.real_elements(Y))
from sympy.matrices.expressions.hadamard import HadamardProduct
assert ask(Q.real_elements(HadamardProduct(X, Y)),
Q.real_elements(X) & Q.real_elements(Y))
assert ask(Q.complex_elements(X+Y), Q.real_elements(X) & Q.complex_elements(Y))
assert ask(Q.real_elements(X.T), Q.real_elements(X))
assert ask(Q.real_elements(X.I), Q.real_elements(X) & Q.invertible(X))
assert ask(Q.real_elements(Trace(X)), Q.real_elements(X))
assert ask(Q.integer_elements(Determinant(X)), Q.integer_elements(X))
assert not ask(Q.integer_elements(X.I), Q.integer_elements(X))
alpha = Symbol('alpha')
assert ask(Q.real_elements(alpha*X), Q.real_elements(X) & Q.real(alpha))
assert ask(Q.real_elements(LofLU(X)), Q.real_elements(X))
e = Symbol('e', integer=True, negative=True)
assert ask(Q.real_elements(X**e), Q.real_elements(X) & Q.invertible(X))
assert ask(Q.real_elements(X**e), Q.real_elements(X)) is None
def test_matrix_element_sets():
X = MatrixSymbol('X', 4, 4)
assert ask(Q.real(X[1, 2]), Q.real_elements(X))
assert ask(Q.integer(X[1, 2]), Q.integer_elements(X))
assert ask(Q.complex(X[1, 2]), Q.complex_elements(X))
assert ask(Q.integer_elements(Identity(3)))
assert ask(Q.integer_elements(ZeroMatrix(3, 3)))
from sympy.matrices.expressions.fourier import DFT
assert ask(Q.complex_elements(DFT(3)))
def test_matrix_element_sets_slices_blocks():
from sympy.matrices.expressions import BlockMatrix
X = MatrixSymbol('X', 4, 4)
assert ask(Q.integer_elements(X[:, 3]), Q.integer_elements(X))
assert ask(Q.integer_elements(BlockMatrix([[X], [X]])),
Q.integer_elements(X))
def test_matrix_element_sets_determinant_trace():
assert ask(Q.integer(Determinant(X)), Q.integer_elements(X))
assert ask(Q.integer(Trace(X)), Q.integer_elements(X))
|
6b1a50e826aee9592ec4ee2f6931632da08184a429db500a1d2082c9b2029fa8
|
from __future__ import print_function, division
from sympy.core import S, sympify
from sympy.core.add import Add
from sympy.core.containers import Tuple
from sympy.core.operations import LatticeOp, ShortCircuit
from sympy.core.function import (Application, Lambda,
ArgumentIndexError)
from sympy.core.expr import Expr
from sympy.core.mod import Mod
from sympy.core.mul import Mul
from sympy.core.numbers import Rational
from sympy.core.power import Pow
from sympy.core.relational import Eq, Relational
from sympy.core.singleton import Singleton
from sympy.core.symbol import Dummy
from sympy.core.rules import Transform
from sympy.core.compatibility import as_int, with_metaclass, range
from sympy.core.logic import fuzzy_and, fuzzy_or, _torf
from sympy.functions.elementary.integers import floor
from sympy.logic.boolalg import And, Or
def _minmax_as_Piecewise(op, *args):
# helper for Min/Max rewrite as Piecewise
from sympy.functions.elementary.piecewise import Piecewise
ec = []
for i, a in enumerate(args):
c = []
for j in range(i + 1, len(args)):
c.append(Relational(a, args[j], op))
ec.append((a, And(*c)))
return Piecewise(*ec)
class IdentityFunction(with_metaclass(Singleton, Lambda)):
"""
The identity function
Examples
========
>>> from sympy import Id, Symbol
>>> x = Symbol('x')
>>> Id(x)
x
"""
def __new__(cls):
from sympy.sets.sets import FiniteSet
x = Dummy('x')
#construct "by hand" to avoid infinite loop
obj = Expr.__new__(cls, Tuple(x), x)
obj.nargs = FiniteSet(1)
return obj
Id = S.IdentityFunction
###############################################################################
############################# ROOT and SQUARE ROOT FUNCTION ###################
###############################################################################
def sqrt(arg, evaluate=None):
"""The square root function
sqrt(x) -> Returns the principal square root of x.
The parameter evaluate determines if the expression should be evaluated.
If None, its value is taken from global_evaluate
Examples
========
>>> from sympy import sqrt, Symbol
>>> x = Symbol('x')
>>> sqrt(x)
sqrt(x)
>>> sqrt(x)**2
x
Note that sqrt(x**2) does not simplify to x.
>>> sqrt(x**2)
sqrt(x**2)
This is because the two are not equal to each other in general.
For example, consider x == -1:
>>> from sympy import Eq
>>> Eq(sqrt(x**2), x).subs(x, -1)
False
This is because sqrt computes the principal square root, so the square may
put the argument in a different branch. This identity does hold if x is
positive:
>>> y = Symbol('y', positive=True)
>>> sqrt(y**2)
y
You can force this simplification by using the powdenest() function with
the force option set to True:
>>> from sympy import powdenest
>>> sqrt(x**2)
sqrt(x**2)
>>> powdenest(sqrt(x**2), force=True)
x
To get both branches of the square root you can use the rootof function:
>>> from sympy import rootof
>>> [rootof(x**2-3,i) for i in (0,1)]
[-sqrt(3), sqrt(3)]
See Also
========
sympy.polys.rootoftools.rootof, root, real_root
References
==========
.. [1] https://en.wikipedia.org/wiki/Square_root
.. [2] https://en.wikipedia.org/wiki/Principal_value
"""
# arg = sympify(arg) is handled by Pow
return Pow(arg, S.Half, evaluate=evaluate)
def cbrt(arg, evaluate=None):
"""This function computes the principal cube root of `arg`, so
it's just a shortcut for `arg**Rational(1, 3)`.
The parameter evaluate determines if the expression should be evaluated.
If None, its value is taken from global_evaluate.
Examples
========
>>> from sympy import cbrt, Symbol
>>> x = Symbol('x')
>>> cbrt(x)
x**(1/3)
>>> cbrt(x)**3
x
Note that cbrt(x**3) does not simplify to x.
>>> cbrt(x**3)
(x**3)**(1/3)
This is because the two are not equal to each other in general.
For example, consider `x == -1`:
>>> from sympy import Eq
>>> Eq(cbrt(x**3), x).subs(x, -1)
False
This is because cbrt computes the principal cube root, this
identity does hold if `x` is positive:
>>> y = Symbol('y', positive=True)
>>> cbrt(y**3)
y
See Also
========
sympy.polys.rootoftools.rootof, root, real_root
References
==========
* https://en.wikipedia.org/wiki/Cube_root
* https://en.wikipedia.org/wiki/Principal_value
"""
return Pow(arg, Rational(1, 3), evaluate=evaluate)
def root(arg, n, k=0, evaluate=None):
"""root(x, n, k) -> Returns the k-th n-th root of x, defaulting to the
principal root (k=0).
The parameter evaluate determines if the expression should be evaluated.
If None, its value is taken from global_evaluate.
Examples
========
>>> from sympy import root, Rational
>>> from sympy.abc import x, n
>>> root(x, 2)
sqrt(x)
>>> root(x, 3)
x**(1/3)
>>> root(x, n)
x**(1/n)
>>> root(x, -Rational(2, 3))
x**(-3/2)
To get the k-th n-th root, specify k:
>>> root(-2, 3, 2)
-(-1)**(2/3)*2**(1/3)
To get all n n-th roots you can use the rootof function.
The following examples show the roots of unity for n
equal 2, 3 and 4:
>>> from sympy import rootof, I
>>> [rootof(x**2 - 1, i) for i in range(2)]
[-1, 1]
>>> [rootof(x**3 - 1,i) for i in range(3)]
[1, -1/2 - sqrt(3)*I/2, -1/2 + sqrt(3)*I/2]
>>> [rootof(x**4 - 1,i) for i in range(4)]
[-1, 1, -I, I]
SymPy, like other symbolic algebra systems, returns the
complex root of negative numbers. This is the principal
root and differs from the text-book result that one might
be expecting. For example, the cube root of -8 does not
come back as -2:
>>> root(-8, 3)
2*(-1)**(1/3)
The real_root function can be used to either make the principal
result real (or simply to return the real root directly):
>>> from sympy import real_root
>>> real_root(_)
-2
>>> real_root(-32, 5)
-2
Alternatively, the n//2-th n-th root of a negative number can be
computed with root:
>>> root(-32, 5, 5//2)
-2
See Also
========
sympy.polys.rootoftools.rootof
sympy.core.power.integer_nthroot
sqrt, real_root
References
==========
* https://en.wikipedia.org/wiki/Square_root
* https://en.wikipedia.org/wiki/Real_root
* https://en.wikipedia.org/wiki/Root_of_unity
* https://en.wikipedia.org/wiki/Principal_value
* http://mathworld.wolfram.com/CubeRoot.html
"""
n = sympify(n)
if k:
return Mul(Pow(arg, S.One/n, evaluate=evaluate), S.NegativeOne**(2*k/n), evaluate=evaluate)
return Pow(arg, 1/n, evaluate=evaluate)
def real_root(arg, n=None, evaluate=None):
"""Return the real nth-root of arg if possible. If n is omitted then
all instances of (-n)**(1/odd) will be changed to -n**(1/odd); this
will only create a real root of a principal root -- the presence of
other factors may cause the result to not be real.
The parameter evaluate determines if the expression should be evaluated.
If None, its value is taken from global_evaluate.
Examples
========
>>> from sympy import root, real_root, Rational
>>> from sympy.abc import x, n
>>> real_root(-8, 3)
-2
>>> root(-8, 3)
2*(-1)**(1/3)
>>> real_root(_)
-2
If one creates a non-principal root and applies real_root, the
result will not be real (so use with caution):
>>> root(-8, 3, 2)
-2*(-1)**(2/3)
>>> real_root(_)
-2*(-1)**(2/3)
See Also
========
sympy.polys.rootoftools.rootof
sympy.core.power.integer_nthroot
root, sqrt
"""
from sympy.functions.elementary.complexes import Abs, im, sign
from sympy.functions.elementary.piecewise import Piecewise
if n is not None:
return Piecewise(
(root(arg, n, evaluate=evaluate), Or(Eq(n, S.One), Eq(n, S.NegativeOne))),
(Mul(sign(arg), root(Abs(arg), n, evaluate=evaluate), evaluate=evaluate),
And(Eq(im(arg), S.Zero), Eq(Mod(n, 2), S.One))),
(root(arg, n, evaluate=evaluate), True))
rv = sympify(arg)
n1pow = Transform(lambda x: -(-x.base)**x.exp,
lambda x:
x.is_Pow and
x.base.is_negative and
x.exp.is_Rational and
x.exp.p == 1 and x.exp.q % 2)
return rv.xreplace(n1pow)
###############################################################################
############################# MINIMUM and MAXIMUM #############################
###############################################################################
class MinMaxBase(Expr, LatticeOp):
def __new__(cls, *args, **assumptions):
args = (sympify(arg) for arg in args)
# first standard filter, for cls.zero and cls.identity
# also reshape Max(a, Max(b, c)) to Max(a, b, c)
try:
args = frozenset(cls._new_args_filter(args))
except ShortCircuit:
return cls.zero
if assumptions.pop('evaluate', True):
# remove redundant args that are easily identified
args = cls._collapse_arguments(args, **assumptions)
# find local zeros
args = cls._find_localzeros(args, **assumptions)
if not args:
return cls.identity
if len(args) == 1:
return list(args).pop()
# base creation
_args = frozenset(args)
obj = Expr.__new__(cls, _args, **assumptions)
obj._argset = _args
return obj
@classmethod
def _collapse_arguments(cls, args, **assumptions):
"""Remove redundant args.
Examples
========
>>> from sympy import Min, Max
>>> from sympy.abc import a, b, c, d, e
Any arg in parent that appears in any
parent-like function in any of the flat args
of parent can be removed from that sub-arg:
>>> Min(a, Max(b, Min(a, c, d)))
Min(a, Max(b, Min(c, d)))
If the arg of parent appears in an opposite-than parent
function in any of the flat args of parent that function
can be replaced with the arg:
>>> Min(a, Max(b, Min(c, d, Max(a, e))))
Min(a, Max(b, Min(a, c, d)))
"""
from sympy.utilities.iterables import ordered
from sympy.utilities.iterables import sift
from sympy.simplify.simplify import walk
if not args:
return args
args = list(ordered(args))
if cls == Min:
other = Max
else:
other = Min
# find global comparable max of Max and min of Min if a new
# value is being introduced in these args at position 0 of
# the ordered args
if args[0].is_number:
sifted = mins, maxs = [], []
for i in args:
for v in walk(i, Min, Max):
if v.args[0].is_comparable:
sifted[isinstance(v, Max)].append(v)
small = Min.identity
for i in mins:
v = i.args[0]
if v.is_number and (v < small) == True:
small = v
big = Max.identity
for i in maxs:
v = i.args[0]
if v.is_number and (v > big) == True:
big = v
# at the point when this function is called from __new__,
# there may be more than one numeric arg present since
# local zeros have not been handled yet, so look through
# more than the first arg
if cls == Min:
for i in range(len(args)):
if not args[i].is_number:
break
if (args[i] < small) == True:
small = args[i]
elif cls == Max:
for i in range(len(args)):
if not args[i].is_number:
break
if (args[i] > big) == True:
big = args[i]
T = None
if cls == Min:
if small != Min.identity:
other = Max
T = small
elif big != Max.identity:
other = Min
T = big
if T is not None:
# remove numerical redundancy
for i in range(len(args)):
a = args[i]
if isinstance(a, other):
a0 = a.args[0]
if ((a0 > T) if other == Max else (a0 < T)) == True:
args[i] = cls.identity
# remove redundant symbolic args
def do(ai, a):
if not isinstance(ai, (Min, Max)):
return ai
cond = a in ai.args
if not cond:
return ai.func(*[do(i, a) for i in ai.args],
evaluate=False)
if isinstance(ai, cls):
return ai.func(*[do(i, a) for i in ai.args if i != a],
evaluate=False)
return a
for i, a in enumerate(args):
args[i + 1:] = [do(ai, a) for ai in args[i + 1:]]
# factor out common elements as for
# Min(Max(x, y), Max(x, z)) -> Max(x, Min(y, z))
# and vice versa when swapping Min/Max -- do this only for the
# easy case where all functions contain something in common;
# trying to find some optimal subset of args to modify takes
# too long
if len(args) > 1:
common = None
remove = []
sets = []
for i in range(len(args)):
a = args[i]
if not isinstance(a, other):
continue
s = set(a.args)
common = s if common is None else (common & s)
if not common:
break
sets.append(s)
remove.append(i)
if common:
sets = filter(None, [s - common for s in sets])
sets = [other(*s, evaluate=False) for s in sets]
for i in reversed(remove):
args.pop(i)
oargs = [cls(*sets)] if sets else []
oargs.extend(common)
args.append(other(*oargs, evaluate=False))
return args
@classmethod
def _new_args_filter(cls, arg_sequence):
"""
Generator filtering args.
first standard filter, for cls.zero and cls.identity.
Also reshape Max(a, Max(b, c)) to Max(a, b, c),
and check arguments for comparability
"""
for arg in arg_sequence:
# pre-filter, checking comparability of arguments
if not isinstance(arg, Expr) or arg.is_real is False or (
arg.is_number and
not arg.is_comparable):
raise ValueError("The argument '%s' is not comparable." % arg)
if arg == cls.zero:
raise ShortCircuit(arg)
elif arg == cls.identity:
continue
elif arg.func == cls:
for x in arg.args:
yield x
else:
yield arg
@classmethod
def _find_localzeros(cls, values, **options):
"""
Sequentially allocate values to localzeros.
When a value is identified as being more extreme than another member it
replaces that member; if this is never true, then the value is simply
appended to the localzeros.
"""
localzeros = set()
for v in values:
is_newzero = True
localzeros_ = list(localzeros)
for z in localzeros_:
if id(v) == id(z):
is_newzero = False
else:
con = cls._is_connected(v, z)
if con:
is_newzero = False
if con is True or con == cls:
localzeros.remove(z)
localzeros.update([v])
if is_newzero:
localzeros.update([v])
return localzeros
@classmethod
def _is_connected(cls, x, y):
"""
Check if x and y are connected somehow.
"""
from sympy.core.exprtools import factor_terms
def hit(v, t, f):
if not v.is_Relational:
return t if v else f
for i in range(2):
if x == y:
return True
r = hit(x >= y, Max, Min)
if r is not None:
return r
r = hit(y <= x, Max, Min)
if r is not None:
return r
r = hit(x <= y, Min, Max)
if r is not None:
return r
r = hit(y >= x, Min, Max)
if r is not None:
return r
# simplification can be expensive, so be conservative
# in what is attempted
x = factor_terms(x - y)
y = S.Zero
return False
def _eval_derivative(self, s):
# f(x).diff(s) -> x.diff(s) * f.fdiff(1)(s)
i = 0
l = []
for a in self.args:
i += 1
da = a.diff(s)
if da is S.Zero:
continue
try:
df = self.fdiff(i)
except ArgumentIndexError:
df = Function.fdiff(self, i)
l.append(df * da)
return Add(*l)
def _eval_rewrite_as_Abs(self, *args, **kwargs):
from sympy.functions.elementary.complexes import Abs
s = (args[0] + self.func(*args[1:]))/2
d = abs(args[0] - self.func(*args[1:]))/2
return (s + d if isinstance(self, Max) else s - d).rewrite(Abs)
def evalf(self, prec=None, **options):
return self.func(*[a.evalf(prec, **options) for a in self.args])
n = evalf
_eval_is_algebraic = lambda s: _torf(i.is_algebraic for i in s.args)
_eval_is_antihermitian = lambda s: _torf(i.is_antihermitian for i in s.args)
_eval_is_commutative = lambda s: _torf(i.is_commutative for i in s.args)
_eval_is_complex = lambda s: _torf(i.is_complex for i in s.args)
_eval_is_composite = lambda s: _torf(i.is_composite for i in s.args)
_eval_is_even = lambda s: _torf(i.is_even for i in s.args)
_eval_is_finite = lambda s: _torf(i.is_finite for i in s.args)
_eval_is_hermitian = lambda s: _torf(i.is_hermitian for i in s.args)
_eval_is_imaginary = lambda s: _torf(i.is_imaginary for i in s.args)
_eval_is_infinite = lambda s: _torf(i.is_infinite for i in s.args)
_eval_is_integer = lambda s: _torf(i.is_integer for i in s.args)
_eval_is_irrational = lambda s: _torf(i.is_irrational for i in s.args)
_eval_is_negative = lambda s: _torf(i.is_negative for i in s.args)
_eval_is_noninteger = lambda s: _torf(i.is_noninteger for i in s.args)
_eval_is_nonnegative = lambda s: _torf(i.is_nonnegative for i in s.args)
_eval_is_nonpositive = lambda s: _torf(i.is_nonpositive for i in s.args)
_eval_is_nonzero = lambda s: _torf(i.is_nonzero for i in s.args)
_eval_is_odd = lambda s: _torf(i.is_odd for i in s.args)
_eval_is_polar = lambda s: _torf(i.is_polar for i in s.args)
_eval_is_positive = lambda s: _torf(i.is_positive for i in s.args)
_eval_is_prime = lambda s: _torf(i.is_prime for i in s.args)
_eval_is_rational = lambda s: _torf(i.is_rational for i in s.args)
_eval_is_real = lambda s: _torf(i.is_real for i in s.args)
_eval_is_transcendental = lambda s: _torf(i.is_transcendental for i in s.args)
_eval_is_zero = lambda s: _torf(i.is_zero for i in s.args)
class Max(MinMaxBase, Application):
"""
Return, if possible, the maximum value of the list.
When number of arguments is equal one, then
return this argument.
When number of arguments is equal two, then
return, if possible, the value from (a, b) that is >= the other.
In common case, when the length of list greater than 2, the task
is more complicated. Return only the arguments, which are greater
than others, if it is possible to determine directional relation.
If is not possible to determine such a relation, return a partially
evaluated result.
Assumptions are used to make the decision too.
Also, only comparable arguments are permitted.
It is named ``Max`` and not ``max`` to avoid conflicts
with the built-in function ``max``.
Examples
========
>>> from sympy import Max, Symbol, oo
>>> from sympy.abc import x, y
>>> p = Symbol('p', positive=True)
>>> n = Symbol('n', negative=True)
>>> Max(x, -2) #doctest: +SKIP
Max(x, -2)
>>> Max(x, -2).subs(x, 3)
3
>>> Max(p, -2)
p
>>> Max(x, y)
Max(x, y)
>>> Max(x, y) == Max(y, x)
True
>>> Max(x, Max(y, z)) #doctest: +SKIP
Max(x, y, z)
>>> Max(n, 8, p, 7, -oo) #doctest: +SKIP
Max(8, p)
>>> Max (1, x, oo)
oo
* Algorithm
The task can be considered as searching of supremums in the
directed complete partial orders [1]_.
The source values are sequentially allocated by the isolated subsets
in which supremums are searched and result as Max arguments.
If the resulted supremum is single, then it is returned.
The isolated subsets are the sets of values which are only the comparable
with each other in the current set. E.g. natural numbers are comparable with
each other, but not comparable with the `x` symbol. Another example: the
symbol `x` with negative assumption is comparable with a natural number.
Also there are "least" elements, which are comparable with all others,
and have a zero property (maximum or minimum for all elements). E.g. `oo`.
In case of it the allocation operation is terminated and only this value is
returned.
Assumption:
- if A > B > C then A > C
- if A == B then B can be removed
References
==========
.. [1] https://en.wikipedia.org/wiki/Directed_complete_partial_order
.. [2] https://en.wikipedia.org/wiki/Lattice_%28order%29
See Also
========
Min : find minimum values
"""
zero = S.Infinity
identity = S.NegativeInfinity
def fdiff( self, argindex ):
from sympy import Heaviside
n = len(self.args)
if 0 < argindex and argindex <= n:
argindex -= 1
if n == 2:
return Heaviside(self.args[argindex] - self.args[1 - argindex])
newargs = tuple([self.args[i] for i in range(n) if i != argindex])
return Heaviside(self.args[argindex] - Max(*newargs))
else:
raise ArgumentIndexError(self, argindex)
def _eval_rewrite_as_Heaviside(self, *args, **kwargs):
from sympy import Heaviside
return Add(*[j*Mul(*[Heaviside(j - i) for i in args if i!=j]) \
for j in args])
def _eval_rewrite_as_Piecewise(self, *args, **kwargs):
is_real = all(i.is_real for i in args)
if is_real:
return _minmax_as_Piecewise('>=', *args)
def _eval_is_positive(self):
return fuzzy_or(a.is_positive for a in self.args)
def _eval_is_nonnegative(self):
return fuzzy_or(a.is_nonnegative for a in self.args)
def _eval_is_negative(self):
return fuzzy_and(a.is_negative for a in self.args)
class Min(MinMaxBase, Application):
"""
Return, if possible, the minimum value of the list.
It is named ``Min`` and not ``min`` to avoid conflicts
with the built-in function ``min``.
Examples
========
>>> from sympy import Min, Symbol, oo
>>> from sympy.abc import x, y
>>> p = Symbol('p', positive=True)
>>> n = Symbol('n', negative=True)
>>> Min(x, -2) #doctest: +SKIP
Min(x, -2)
>>> Min(x, -2).subs(x, 3)
-2
>>> Min(p, -3)
-3
>>> Min(x, y) #doctest: +SKIP
Min(x, y)
>>> Min(n, 8, p, -7, p, oo) #doctest: +SKIP
Min(n, -7)
See Also
========
Max : find maximum values
"""
zero = S.NegativeInfinity
identity = S.Infinity
def fdiff( self, argindex ):
from sympy import Heaviside
n = len(self.args)
if 0 < argindex and argindex <= n:
argindex -= 1
if n == 2:
return Heaviside( self.args[1-argindex] - self.args[argindex] )
newargs = tuple([ self.args[i] for i in range(n) if i != argindex])
return Heaviside( Min(*newargs) - self.args[argindex] )
else:
raise ArgumentIndexError(self, argindex)
def _eval_rewrite_as_Heaviside(self, *args, **kwargs):
from sympy import Heaviside
return Add(*[j*Mul(*[Heaviside(i-j) for i in args if i!=j]) \
for j in args])
def _eval_rewrite_as_Piecewise(self, *args, **kwargs):
is_real = all(i.is_real for i in args)
if is_real:
return _minmax_as_Piecewise('<=', *args)
def _eval_is_positive(self):
return fuzzy_and(a.is_positive for a in self.args)
def _eval_is_nonnegative(self):
return fuzzy_and(a.is_nonnegative for a in self.args)
def _eval_is_negative(self):
return fuzzy_or(a.is_negative for a in self.args)
|
05943f6f70ae8a5d1fb5952dbd4b6aa7da285cf1d9956b532e4be23bcaaaf7e2
|
from __future__ import print_function, division
from sympy.core.singleton import S
from sympy.core.function import Function
from sympy.core import Add
from sympy.core.evalf import get_integer_part, PrecisionExhausted
from sympy.core.numbers import Integer
from sympy.core.relational import Gt, Lt, Ge, Le
from sympy.core.symbol import Symbol
###############################################################################
######################### FLOOR and CEILING FUNCTIONS #########################
###############################################################################
class RoundFunction(Function):
"""The base class for rounding functions."""
@classmethod
def eval(cls, arg):
from sympy import im
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)
v = cls._eval_number(arg)
if v is not None:
return v
# 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
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_nseries(self, x, n, logx):
r = self.subs(x, 0)
args = self.args[0]
args0 = args.subs(x, 0)
if args0 == r:
direction = (args - args0).leadterm(x)[0]
if direction.is_positive:
return r
else:
return r - 1
else:
return r
def _eval_rewrite_as_ceiling(self, arg, **kwargs):
return -ceiling(-arg)
def _eval_rewrite_as_frac(self, arg, **kwargs):
return arg - frac(arg)
def _eval_Eq(self, other):
if isinstance(self, floor):
if (self.rewrite(ceiling) == other) or \
(self.rewrite(frac) == other):
return S.true
def __le__(self, other):
if self.args[0] == other and other.is_real:
return S.true
return Le(self, other, evaluate=False)
def __gt__(self, other):
if self.args[0] == other and other.is_real:
return S.false
return Gt(self, other, evaluate=False)
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_nseries(self, x, n, logx):
r = self.subs(x, 0)
args = self.args[0]
args0 = args.subs(x, 0)
if args0 == r:
direction = (args - args0).leadterm(x)[0]
if direction.is_positive:
return r + 1
else:
return r
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_Eq(self, other):
if isinstance(self, ceiling):
if (self.rewrite(floor) == other) or \
(self.rewrite(frac) == other):
return S.true
def __lt__(self, other):
if self.args[0] == other and other.is_real:
return S.false
return Lt(self, other, evaluate=False)
def __ge__(self, other):
if self.args[0] == other and other.is_real:
return S.true
return Ge(self, other, evaluate=False)
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, ceiling, 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 None
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_Eq(self, other):
if isinstance(self, frac):
if (self.rewrite(floor) == other) or \
(self.rewrite(ceiling) == other):
return S.true
|
48667b47bf5578d516951e5a50b4db51bdfbbb13a00a4125c54f529c43206ba2
|
import itertools as it
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.functions.elementary.miscellaneous import (sqrt, cbrt, root, Min,
Max, real_root)
from sympy.functions.elementary.trigonometric import cos, sin
from sympy.functions.elementary.exponential import log
from sympy.functions.elementary.integers import floor, ceiling
from sympy.functions.special.delta_functions import Heaviside
from sympy.utilities.lambdify import lambdify
from sympy.utilities.pytest import raises, skip, warns
from sympy.external import import_module
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) == -oo
assert Min(-oo, n) == -oo
assert Min(n, -oo) == -oo
assert Min(-oo, np) == -oo
assert Min(np, -oo) == -oo
assert Min(-oo, 0) == -oo
assert Min(0, -oo) == -oo
assert Min(-oo, nn) == -oo
assert Min(nn, -oo) == -oo
assert Min(-oo, p) == -oo
assert Min(p, -oo) == -oo
assert Min(-oo, oo) == -oo
assert Min(oo, -oo) == -oo
assert Min(n, n) == n
assert Min(n, np) == Min(n, np)
assert Min(np, n) == Min(np, n)
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 Min(nn, p) == Min(nn, p)
assert Min(p, nn) == Min(p, nn)
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) == 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() == 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 Min(cos(x), sin(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(1)/2) == sin(S(1)/2)
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.evalf == e.n
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)
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 Max(5, 4) == 5
# lists
assert Max() == 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(1)/2) == cos(S(1)/2)
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.evalf == e.n
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', real=True, rational=False)
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 warns(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 not takes place for non-real arguments
assert Max(vx, vy).rewrite(Piecewise) == Max(vx, vy)
assert Min(va, vx, vy).rewrite(Piecewise) == Min(va, vx, vy)
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, d
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_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) == set(
[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, Rational(1, 2), evaluate=False)
assert root(16, 4, 2, evaluate=False).has(Pow) == True
assert real_root(-8, 3, evaluate=False).has(Pow) == True
|
4e7334044effb5e5c43855c54008e90ca1710c7b6cf3aeb969039556f3ddffd7
|
# Tests that require installed backends go into
# sympy/test_external/test_autowrap
import os
import tempfile
import shutil
from sympy.core import symbols, Eq
from sympy.core.compatibility import StringIO
from sympy.utilities.autowrap import (autowrap, binary_function,
CythonCodeWrapper, UfuncifyCodeWrapper, CodeWrapper)
from sympy.utilities.codegen import (
CCodeGen, C99CodeGen, CodeGenArgumentListError, make_routine
)
from sympy.utilities.pytest import raises
from sympy.utilities.tmpfiles import TmpFileManager
def get_string(dump_fn, routines, prefix="file", **kwargs):
"""Wrapper for dump_fn. dump_fn writes its results to a stream object and
this wrapper returns the contents of that stream as a string. This
auxiliary function is used by many tests below.
The header and the empty lines are not generator to facilitate the
testing of the output.
"""
output = StringIO()
dump_fn(routines, output, prefix, **kwargs)
source = output.getvalue()
output.close()
return source
def test_cython_wrapper_scalar_function():
x, y, z = symbols('x,y,z')
expr = (x + y)*z
routine = make_routine("test", expr)
code_gen = CythonCodeWrapper(CCodeGen())
source = get_string(code_gen.dump_pyx, [routine])
expected = (
"cdef extern from 'file.h':\n"
" double test(double x, double y, double z)\n"
"\n"
"def test_c(double x, double y, double z):\n"
"\n"
" return test(x, y, z)")
assert source == expected
def test_cython_wrapper_outarg():
from sympy import Equality
x, y, z = symbols('x,y,z')
code_gen = CythonCodeWrapper(C99CodeGen())
routine = make_routine("test", Equality(z, x + y))
source = get_string(code_gen.dump_pyx, [routine])
expected = (
"cdef extern from 'file.h':\n"
" void test(double x, double y, double *z)\n"
"\n"
"def test_c(double x, double y):\n"
"\n"
" cdef double z = 0\n"
" test(x, y, &z)\n"
" return z")
assert source == expected
def test_cython_wrapper_inoutarg():
from sympy import Equality
x, y, z = symbols('x,y,z')
code_gen = CythonCodeWrapper(C99CodeGen())
routine = make_routine("test", Equality(z, x + y + z))
source = get_string(code_gen.dump_pyx, [routine])
expected = (
"cdef extern from 'file.h':\n"
" void test(double x, double y, double *z)\n"
"\n"
"def test_c(double x, double y, double z):\n"
"\n"
" test(x, y, &z)\n"
" return z")
assert source == expected
def test_cython_wrapper_compile_flags():
from sympy import Equality
x, y, z = symbols('x,y,z')
routine = make_routine("test", Equality(z, x + y))
code_gen = CythonCodeWrapper(CCodeGen())
expected = """\
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 = {}
ext_mods = [Extension(
'wrapper_module_%(num)s', ['wrapper_module_%(num)s.pyx', 'wrapped_code_%(num)s.c'],
include_dirs=[],
library_dirs=[],
libraries=[],
extra_compile_args=['-std=c99'],
extra_link_args=[]
)]
setup(ext_modules=cythonize(ext_mods, **cy_opts))
""" % {'num': CodeWrapper._module_counter}
temp_dir = tempfile.mkdtemp()
TmpFileManager.tmp_folder(temp_dir)
setup_file_path = os.path.join(temp_dir, 'setup.py')
code_gen._prepare_files(routine, build_dir=temp_dir)
with open(setup_file_path) as f:
setup_text = f.read()
assert setup_text == expected
code_gen = CythonCodeWrapper(CCodeGen(),
include_dirs=['/usr/local/include', '/opt/booger/include'],
library_dirs=['/user/local/lib'],
libraries=['thelib', 'nilib'],
extra_compile_args=['-slow-math'],
extra_link_args=['-lswamp', '-ltrident'],
cythonize_options={'compiler_directives': {'boundscheck': False}}
)
expected = """\
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 = {'compiler_directives': {'boundscheck': False}}
ext_mods = [Extension(
'wrapper_module_%(num)s', ['wrapper_module_%(num)s.pyx', 'wrapped_code_%(num)s.c'],
include_dirs=['/usr/local/include', '/opt/booger/include'],
library_dirs=['/user/local/lib'],
libraries=['thelib', 'nilib'],
extra_compile_args=['-slow-math', '-std=c99'],
extra_link_args=['-lswamp', '-ltrident']
)]
setup(ext_modules=cythonize(ext_mods, **cy_opts))
""" % {'num': CodeWrapper._module_counter}
code_gen._prepare_files(routine, build_dir=temp_dir)
with open(setup_file_path) as f:
setup_text = f.read()
assert setup_text == expected
expected = """\
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 = {'compiler_directives': {'boundscheck': False}}
import numpy as np
ext_mods = [Extension(
'wrapper_module_%(num)s', ['wrapper_module_%(num)s.pyx', 'wrapped_code_%(num)s.c'],
include_dirs=['/usr/local/include', '/opt/booger/include', np.get_include()],
library_dirs=['/user/local/lib'],
libraries=['thelib', 'nilib'],
extra_compile_args=['-slow-math', '-std=c99'],
extra_link_args=['-lswamp', '-ltrident']
)]
setup(ext_modules=cythonize(ext_mods, **cy_opts))
""" % {'num': CodeWrapper._module_counter}
code_gen._need_numpy = True
code_gen._prepare_files(routine, build_dir=temp_dir)
with open(setup_file_path) as f:
setup_text = f.read()
assert setup_text == expected
TmpFileManager.cleanup()
def test_autowrap_dummy():
x, y, z = symbols('x y z')
# Uses DummyWrapper to test that codegen works as expected
f = autowrap(x + y, backend='dummy')
assert f() == str(x + y)
assert f.args == "x, y"
assert f.returns == "nameless"
f = autowrap(Eq(z, x + y), backend='dummy')
assert f() == str(x + y)
assert f.args == "x, y"
assert f.returns == "z"
f = autowrap(Eq(z, x + y + z), backend='dummy')
assert f() == str(x + y + z)
assert f.args == "x, y, z"
assert f.returns == "z"
def test_autowrap_args():
x, y, z = symbols('x y z')
raises(CodeGenArgumentListError, lambda: autowrap(Eq(z, x + y),
backend='dummy', args=[x]))
f = autowrap(Eq(z, x + y), backend='dummy', args=[y, x])
assert f() == str(x + y)
assert f.args == "y, x"
assert f.returns == "z"
raises(CodeGenArgumentListError, lambda: autowrap(Eq(z, x + y + z),
backend='dummy', args=[x, y]))
f = autowrap(Eq(z, x + y + z), backend='dummy', args=[y, x, z])
assert f() == str(x + y + z)
assert f.args == "y, x, z"
assert f.returns == "z"
f = autowrap(Eq(z, x + y + z), backend='dummy', args=(y, x, z))
assert f() == str(x + y + z)
assert f.args == "y, x, z"
assert f.returns == "z"
def test_autowrap_store_files():
x, y = symbols('x y')
tmp = tempfile.mkdtemp()
TmpFileManager.tmp_folder(tmp)
f = autowrap(x + y, backend='dummy', tempdir=tmp)
assert f() == str(x + y)
assert os.access(tmp, os.F_OK)
TmpFileManager.cleanup()
def test_autowrap_store_files_issue_gh12939():
x, y = symbols('x y')
tmp = './tmp'
try:
f = autowrap(x + y, backend='dummy', tempdir=tmp)
assert f() == str(x + y)
assert os.access(tmp, os.F_OK)
finally:
shutil.rmtree(tmp)
def test_binary_function():
x, y = symbols('x y')
f = binary_function('f', x + y, backend='dummy')
assert f._imp_() == str(x + y)
def test_ufuncify_source():
x, y, z = symbols('x,y,z')
code_wrapper = UfuncifyCodeWrapper(C99CodeGen("ufuncify"))
routine = make_routine("test", x + y + z)
source = get_string(code_wrapper.dump_c, [routine])
expected = """\
#include "Python.h"
#include "math.h"
#include "numpy/ndarraytypes.h"
#include "numpy/ufuncobject.h"
#include "numpy/halffloat.h"
#include "file.h"
static PyMethodDef wrapper_module_%(num)sMethods[] = {
{NULL, NULL, 0, NULL}
};
static void test_ufunc(char **args, npy_intp *dimensions, npy_intp* steps, void* data)
{
npy_intp i;
npy_intp n = dimensions[0];
char *in0 = args[0];
char *in1 = args[1];
char *in2 = args[2];
char *out0 = args[3];
npy_intp in0_step = steps[0];
npy_intp in1_step = steps[1];
npy_intp in2_step = steps[2];
npy_intp out0_step = steps[3];
for (i = 0; i < n; i++) {
*((double *)out0) = test(*(double *)in0, *(double *)in1, *(double *)in2);
in0 += in0_step;
in1 += in1_step;
in2 += in2_step;
out0 += out0_step;
}
}
PyUFuncGenericFunction test_funcs[1] = {&test_ufunc};
static char test_types[4] = {NPY_DOUBLE, NPY_DOUBLE, NPY_DOUBLE, NPY_DOUBLE};
static void *test_data[1] = {NULL};
#if PY_VERSION_HEX >= 0x03000000
static struct PyModuleDef moduledef = {
PyModuleDef_HEAD_INIT,
"wrapper_module_%(num)s",
NULL,
-1,
wrapper_module_%(num)sMethods,
NULL,
NULL,
NULL,
NULL
};
PyMODINIT_FUNC PyInit_wrapper_module_%(num)s(void)
{
PyObject *m, *d;
PyObject *ufunc0;
m = PyModule_Create(&moduledef);
if (!m) {
return NULL;
}
import_array();
import_umath();
d = PyModule_GetDict(m);
ufunc0 = PyUFunc_FromFuncAndData(test_funcs, test_data, test_types, 1, 3, 1,
PyUFunc_None, "wrapper_module_%(num)s", "Created in SymPy with Ufuncify", 0);
PyDict_SetItemString(d, "test", ufunc0);
Py_DECREF(ufunc0);
return m;
}
#else
PyMODINIT_FUNC initwrapper_module_%(num)s(void)
{
PyObject *m, *d;
PyObject *ufunc0;
m = Py_InitModule("wrapper_module_%(num)s", wrapper_module_%(num)sMethods);
if (m == NULL) {
return;
}
import_array();
import_umath();
d = PyModule_GetDict(m);
ufunc0 = PyUFunc_FromFuncAndData(test_funcs, test_data, test_types, 1, 3, 1,
PyUFunc_None, "wrapper_module_%(num)s", "Created in SymPy with Ufuncify", 0);
PyDict_SetItemString(d, "test", ufunc0);
Py_DECREF(ufunc0);
}
#endif""" % {'num': CodeWrapper._module_counter}
assert source == expected
def test_ufuncify_source_multioutput():
x, y, z = symbols('x,y,z')
var_symbols = (x, y, z)
expr = x + y**3 + 10*z**2
code_wrapper = UfuncifyCodeWrapper(C99CodeGen("ufuncify"))
routines = [make_routine("func{}".format(i), expr.diff(var_symbols[i]), var_symbols) for i in range(len(var_symbols))]
source = get_string(code_wrapper.dump_c, routines, funcname='multitest')
expected = """\
#include "Python.h"
#include "math.h"
#include "numpy/ndarraytypes.h"
#include "numpy/ufuncobject.h"
#include "numpy/halffloat.h"
#include "file.h"
static PyMethodDef wrapper_module_%(num)sMethods[] = {
{NULL, NULL, 0, NULL}
};
static void multitest_ufunc(char **args, npy_intp *dimensions, npy_intp* steps, void* data)
{
npy_intp i;
npy_intp n = dimensions[0];
char *in0 = args[0];
char *in1 = args[1];
char *in2 = args[2];
char *out0 = args[3];
char *out1 = args[4];
char *out2 = args[5];
npy_intp in0_step = steps[0];
npy_intp in1_step = steps[1];
npy_intp in2_step = steps[2];
npy_intp out0_step = steps[3];
npy_intp out1_step = steps[4];
npy_intp out2_step = steps[5];
for (i = 0; i < n; i++) {
*((double *)out0) = func0(*(double *)in0, *(double *)in1, *(double *)in2);
*((double *)out1) = func1(*(double *)in0, *(double *)in1, *(double *)in2);
*((double *)out2) = func2(*(double *)in0, *(double *)in1, *(double *)in2);
in0 += in0_step;
in1 += in1_step;
in2 += in2_step;
out0 += out0_step;
out1 += out1_step;
out2 += out2_step;
}
}
PyUFuncGenericFunction multitest_funcs[1] = {&multitest_ufunc};
static char multitest_types[6] = {NPY_DOUBLE, NPY_DOUBLE, NPY_DOUBLE, NPY_DOUBLE, NPY_DOUBLE, NPY_DOUBLE};
static void *multitest_data[1] = {NULL};
#if PY_VERSION_HEX >= 0x03000000
static struct PyModuleDef moduledef = {
PyModuleDef_HEAD_INIT,
"wrapper_module_%(num)s",
NULL,
-1,
wrapper_module_%(num)sMethods,
NULL,
NULL,
NULL,
NULL
};
PyMODINIT_FUNC PyInit_wrapper_module_%(num)s(void)
{
PyObject *m, *d;
PyObject *ufunc0;
m = PyModule_Create(&moduledef);
if (!m) {
return NULL;
}
import_array();
import_umath();
d = PyModule_GetDict(m);
ufunc0 = PyUFunc_FromFuncAndData(multitest_funcs, multitest_data, multitest_types, 1, 3, 3,
PyUFunc_None, "wrapper_module_%(num)s", "Created in SymPy with Ufuncify", 0);
PyDict_SetItemString(d, "multitest", ufunc0);
Py_DECREF(ufunc0);
return m;
}
#else
PyMODINIT_FUNC initwrapper_module_%(num)s(void)
{
PyObject *m, *d;
PyObject *ufunc0;
m = Py_InitModule("wrapper_module_%(num)s", wrapper_module_%(num)sMethods);
if (m == NULL) {
return;
}
import_array();
import_umath();
d = PyModule_GetDict(m);
ufunc0 = PyUFunc_FromFuncAndData(multitest_funcs, multitest_data, multitest_types, 1, 3, 3,
PyUFunc_None, "wrapper_module_%(num)s", "Created in SymPy with Ufuncify", 0);
PyDict_SetItemString(d, "multitest", ufunc0);
Py_DECREF(ufunc0);
}
#endif""" % {'num': CodeWrapper._module_counter}
assert source == expected
|
ce0485f3dc69b2dd5e7fb05f324b80f27d3704f814f5fdee0dc6283a9ed9938a
|
""" Tests from Michael Wester's 1999 paper "Review of CAS mathematical
capabilities".
http://www.math.unm.edu/~wester/cas/book/Wester.pdf
See also http://math.unm.edu/~wester/cas_review.html for detailed output of
each tested system.
"""
from sympy import (Rational, symbols, Dummy, factorial, sqrt, log, exp, oo, zoo,
product, binomial, rf, pi, gamma, igcd, factorint, radsimp, combsimp,
npartitions, totient, primerange, factor, simplify, gcd, resultant, expand,
I, trigsimp, tan, sin, cos, cot, diff, nan, limit, EulerGamma, polygamma,
bernoulli, hyper, hyperexpand, besselj, asin, assoc_legendre, Function, re,
im, DiracDelta, chebyshevt, legendre_poly, polylog, series, O,
atan, sinh, cosh, tanh, floor, ceiling, solve, asinh, acot, csc, sec,
LambertW, N, apart, sqrtdenest, factorial2, powdenest, Mul, S, ZZ,
Poly, expand_func, E, Q, And, Or, Ne, Eq, Le, Lt, Min,
ask, refine, AlgebraicNumber, continued_fraction_iterator as cf_i,
continued_fraction_periodic as cf_p, continued_fraction_convergents as cf_c,
continued_fraction_reduce as cf_r, FiniteSet, elliptic_e, elliptic_f,
powsimp, hessian, wronskian, fibonacci, sign, Lambda, Piecewise, Subs,
residue, Derivative, logcombine, Symbol, Intersection, Union,
EmptySet, Interval, Integral, idiff)
import mpmath
from sympy.functions.combinatorial.numbers import stirling
from sympy.functions.special.zeta_functions import zeta
from sympy.integrals.deltafunctions import deltaintegrate
from sympy.utilities.pytest import XFAIL, slow, SKIP, skip, ON_TRAVIS
from sympy.utilities.iterables import partitions
from mpmath import mpi, mpc
from sympy.matrices import Matrix, GramSchmidt, eye
from sympy.matrices.expressions.blockmatrix import BlockMatrix, block_collapse
from sympy.matrices.expressions import MatrixSymbol, ZeroMatrix
from sympy.physics.quantum import Commutator
from sympy.assumptions import assuming
from sympy.polys.rings import vring
from sympy.polys.fields import vfield
from sympy.polys.solvers import solve_lin_sys
from sympy.concrete import Sum
from sympy.concrete.products import Product
from sympy.integrals import integrate
from sympy.integrals.transforms import laplace_transform,\
inverse_laplace_transform, LaplaceTransform, fourier_transform,\
mellin_transform
from sympy.functions.special.error_functions import erf
from sympy.functions.special.delta_functions import Heaviside
from sympy.solvers.recurr import rsolve
from sympy.solvers.solveset import solveset, solveset_real, linsolve
from sympy.solvers.ode import dsolve
from sympy.core.relational import Equality
from sympy.core.compatibility import range
from itertools import islice, takewhile
from sympy.series.fourier import fourier_series
R = Rational
x, y, z = symbols('x y z')
i, j, k, l, m, n = symbols('i j k l m n', integer=True)
f = Function('f')
g = Function('g')
# A. Boolean Logic and Quantifier Elimination
# Not implemented.
# B. Set Theory
def test_B1():
assert (FiniteSet(i, j, j, k, k, k) | FiniteSet(l, k, j) |
FiniteSet(j, m, j)) == FiniteSet(i, j, k, l, m)
def test_B2():
a, b, c = FiniteSet(j), FiniteSet(m), FiniteSet(j, k)
d, e = FiniteSet(i), FiniteSet(j, k, l)
assert (FiniteSet(i, j, j, k, k, k) & FiniteSet(l, k, j) &
FiniteSet(j, m, j)) == Union(a, Intersection(b, Union(c, Intersection(d, FiniteSet(l)))))
# {j} U Intersection({m}, {j, k} U Intersection({i}, {l}))
def test_B3():
assert (FiniteSet(i, j, k, l, m) - FiniteSet(j) ==
FiniteSet(i, k, l, m))
def test_B4():
assert (FiniteSet(*(FiniteSet(i, j)*FiniteSet(k, l))) ==
FiniteSet((i, k), (i, l), (j, k), (j, l)))
# C. Numbers
def test_C1():
assert (factorial(50) ==
30414093201713378043612608166064768844377641568960512000000000000)
def test_C2():
assert (factorint(factorial(50)) == {2: 47, 3: 22, 5: 12, 7: 8,
11: 4, 13: 3, 17: 2, 19: 2, 23: 2, 29: 1, 31: 1, 37: 1,
41: 1, 43: 1, 47: 1})
def test_C3():
assert (factorial2(10), factorial2(9)) == (3840, 945)
# Base conversions; not really implemented by sympy
# Whatever. Take credit!
def test_C4():
assert 0xABC == 2748
def test_C5():
assert 123 == int('234', 7)
def test_C6():
assert int('677', 8) == int('1BF', 16) == 447
def test_C7():
assert log(32768, 8) == 5
def test_C8():
# Modular multiplicative inverse. Would be nice if divmod could do this.
assert ZZ.invert(5, 7) == 3
assert ZZ.invert(5, 6) == 5
def test_C9():
assert igcd(igcd(1776, 1554), 5698) == 74
def test_C10():
x = 0
for n in range(2, 11):
x += R(1, n)
assert x == R(4861, 2520)
def test_C11():
assert R(1, 7) == S('0.[142857]')
def test_C12():
assert R(7, 11) * R(22, 7) == 2
def test_C13():
test = R(10, 7) * (1 + R(29, 1000)) ** R(1, 3)
good = 3 ** R(1, 3)
assert test == good
def test_C14():
assert sqrtdenest(sqrt(2*sqrt(3) + 4)) == 1 + sqrt(3)
def test_C15():
test = sqrtdenest(sqrt(14 + 3*sqrt(3 + 2*sqrt(5 - 12*sqrt(3 - 2*sqrt(2))))))
good = sqrt(2) + 3
assert test == good
def test_C16():
test = sqrtdenest(sqrt(10 + 2*sqrt(6) + 2*sqrt(10) + 2*sqrt(15)))
good = sqrt(2) + sqrt(3) + sqrt(5)
assert test == good
def test_C17():
test = radsimp((sqrt(3) + sqrt(2)) / (sqrt(3) - sqrt(2)))
good = 5 + 2*sqrt(6)
assert test == good
def test_C18():
assert simplify((sqrt(-2 + sqrt(-5)) * sqrt(-2 - sqrt(-5))).expand(complex=True)) == 3
@XFAIL
def test_C19():
assert radsimp(simplify((90 + 34*sqrt(7)) ** R(1, 3))) == 3 + sqrt(7)
def test_C20():
inside = (135 + 78*sqrt(3))
test = AlgebraicNumber((inside**R(2, 3) + 3) * sqrt(3) / inside**R(1, 3))
assert simplify(test) == AlgebraicNumber(12)
def test_C21():
assert simplify(AlgebraicNumber((41 + 29*sqrt(2)) ** R(1, 5))) == \
AlgebraicNumber(1 + sqrt(2))
@XFAIL
def test_C22():
test = simplify(((6 - 4*sqrt(2))*log(3 - 2*sqrt(2)) + (3 - 2*sqrt(2))*log(17
- 12*sqrt(2)) + 32 - 24*sqrt(2)) / (48*sqrt(2) - 72))
good = sqrt(2)/3 - log(sqrt(2) - 1)/3
assert test == good
def test_C23():
assert 2 * oo - 3 == oo
@XFAIL
def test_C24():
raise NotImplementedError("2**aleph_null == aleph_1")
# D. Numerical Analysis
def test_D1():
assert 0.0 / sqrt(2) == 0.0
def test_D2():
assert str(exp(-1000000).evalf()) == '3.29683147808856e-434295'
def test_D3():
assert exp(pi*sqrt(163)).evalf(50).num.ae(262537412640768744)
def test_D4():
assert floor(R(-5, 3)) == -2
assert ceiling(R(-5, 3)) == -1
@XFAIL
def test_D5():
raise NotImplementedError("cubic_spline([1, 2, 4, 5], [1, 4, 2, 3], x)(3) == 27/8")
@XFAIL
def test_D6():
raise NotImplementedError("translate sum(a[i]*x**i, (i,1,n)) to FORTRAN")
@XFAIL
def test_D7():
raise NotImplementedError("translate sum(a[i]*x**i, (i,1,n)) to C")
@XFAIL
def test_D8():
# One way is to cheat by converting the sum to a string,
# and replacing the '[' and ']' with ''.
# E.g., horner(S(str(_).replace('[','').replace(']','')))
raise NotImplementedError("apply Horner's rule to sum(a[i]*x**i, (i,1,5))")
@XFAIL
def test_D9():
raise NotImplementedError("translate D8 to FORTRAN")
@XFAIL
def test_D10():
raise NotImplementedError("translate D8 to C")
@XFAIL
def test_D11():
#Is there a way to use count_ops?
raise NotImplementedError("flops(sum(product(f[i][k], (i,1,k)), (k,1,n)))")
@XFAIL
def test_D12():
assert (mpi(-4, 2) * x + mpi(1, 3)) ** 2 == mpi(-8, 16)*x**2 + mpi(-24, 12)*x + mpi(1, 9)
@XFAIL
def test_D13():
raise NotImplementedError("discretize a PDE: diff(f(x,t),t) == diff(diff(f(x,t),x),x)")
# E. Statistics
# See scipy; all of this is numerical.
# F. Combinatorial Theory.
def test_F1():
assert rf(x, 3) == x*(1 + x)*(2 + x)
def test_F2():
assert expand_func(binomial(n, 3)) == n*(n - 1)*(n - 2)/6
@XFAIL
def test_F3():
assert combsimp(2**n * factorial(n) * factorial2(2*n - 1)) == factorial(2*n)
@XFAIL
def test_F4():
assert combsimp((2**n * factorial(n) * product(2*k - 1, (k, 1, n)))) == factorial(2*n)
@XFAIL
def test_F5():
assert gamma(n + R(1, 2)) / sqrt(pi) / factorial(n) == factorial(2*n)/2**(2*n)/factorial(n)**2
def test_F6():
partTest = [p.copy() for p in partitions(4)]
partDesired = [{4: 1}, {1: 1, 3: 1}, {2: 2}, {1: 2, 2:1}, {1: 4}]
assert partTest == partDesired
def test_F7():
assert npartitions(4) == 5
def test_F8():
assert stirling(5, 2, signed=True) == -50 # if signed, then kind=1
def test_F9():
assert totient(1776) == 576
# G. Number Theory
def test_G1():
assert list(primerange(999983, 1000004)) == [999983, 1000003]
@XFAIL
def test_G2():
raise NotImplementedError("find the primitive root of 191 == 19")
@XFAIL
def test_G3():
raise NotImplementedError("(a+b)**p mod p == a**p + b**p mod p; p prime")
# ... G14 Modular equations are not implemented.
def test_G15():
assert Rational(sqrt(3).evalf()).limit_denominator(15) == Rational(26, 15)
assert list(takewhile(lambda x: x.q <= 15, cf_c(cf_i(sqrt(3)))))[-1] == \
Rational(26, 15)
def test_G16():
assert list(islice(cf_i(pi),10)) == [3, 7, 15, 1, 292, 1, 1, 1, 2, 1]
def test_G17():
assert cf_p(0, 1, 23) == [4, [1, 3, 1, 8]]
def test_G18():
assert cf_p(1, 2, 5) == [[1]]
assert cf_r([[1]]) == S.Half + sqrt(5)/2
@XFAIL
def test_G19():
s = symbols('s', integer=True, positive=True)
it = cf_i((exp(1/s) - 1)/(exp(1/s) + 1))
assert list(islice(it, 5)) == [0, 2*s, 6*s, 10*s, 14*s]
def test_G20():
s = symbols('s', integer=True, positive=True)
# Wester erroneously has this as -s + sqrt(s**2 + 1)
assert cf_r([[2*s]]) == s + sqrt(s**2 + 1)
@XFAIL
def test_G20b():
s = symbols('s', integer=True, positive=True)
assert cf_p(s, 1, s**2 + 1) == [[2*s]]
# H. Algebra
def test_H1():
assert simplify(2*2**n) == simplify(2**(n + 1))
assert powdenest(2*2**n) == simplify(2**(n + 1))
def test_H2():
assert powsimp(4 * 2**n) == 2**(n + 2)
def test_H3():
assert (-1)**(n*(n + 1)) == 1
def test_H4():
expr = factor(6*x - 10)
assert type(expr) is Mul
assert expr.args[0] == 2
assert expr.args[1] == 3*x - 5
p1 = 64*x**34 - 21*x**47 - 126*x**8 - 46*x**5 - 16*x**60 - 81
p2 = 72*x**60 - 25*x**25 - 19*x**23 - 22*x**39 - 83*x**52 + 54*x**10 + 81
q = 34*x**19 - 25*x**16 + 70*x**7 + 20*x**3 - 91*x - 86
def test_H5():
assert gcd(p1, p2, x) == 1
def test_H6():
assert gcd(expand(p1 * q), expand(p2 * q)) == q
def test_H7():
p1 = 24*x*y**19*z**8 - 47*x**17*y**5*z**8 + 6*x**15*y**9*z**2 - 3*x**22 + 5
p2 = 34*x**5*y**8*z**13 + 20*x**7*y**7*z**7 + 12*x**9*y**16*z**4 + 80*y**14*z
assert gcd(p1, p2, x, y, z) == 1
def test_H8():
p1 = 24*x*y**19*z**8 - 47*x**17*y**5*z**8 + 6*x**15*y**9*z**2 - 3*x**22 + 5
p2 = 34*x**5*y**8*z**13 + 20*x**7*y**7*z**7 + 12*x**9*y**16*z**4 + 80*y**14*z
q = 11*x**12*y**7*z**13 - 23*x**2*y**8*z**10 + 47*x**17*y**5*z**8
assert gcd(p1 * q, p2 * q, x, y, z) == q
def test_H9():
p1 = 2*x**(n + 4) - x**(n + 2)
p2 = 4*x**(n + 1) + 3*x**n
assert gcd(p1, p2) == x**n
def test_H10():
p1 = 3*x**4 + 3*x**3 + x**2 - x - 2
p2 = x**3 - 3*x**2 + x + 5
assert resultant(p1, p2, x) == 0
def test_H11():
assert resultant(p1 * q, p2 * q, x) == 0
def test_H12():
num = x**2 - 4
den = x**2 + 4*x + 4
assert simplify(num/den) == (x - 2)/(x + 2)
@XFAIL
def test_H13():
assert simplify((exp(x) - 1) / (exp(x/2) + 1)) == exp(x/2) - 1
def test_H14():
p = (x + 1) ** 20
ep = expand(p)
assert ep == (1 + 20*x + 190*x**2 + 1140*x**3 + 4845*x**4 + 15504*x**5
+ 38760*x**6 + 77520*x**7 + 125970*x**8 + 167960*x**9 + 184756*x**10
+ 167960*x**11 + 125970*x**12 + 77520*x**13 + 38760*x**14 + 15504*x**15
+ 4845*x**16 + 1140*x**17 + 190*x**18 + 20*x**19 + x**20)
dep = diff(ep, x)
assert dep == (20 + 380*x + 3420*x**2 + 19380*x**3 + 77520*x**4
+ 232560*x**5 + 542640*x**6 + 1007760*x**7 + 1511640*x**8 + 1847560*x**9
+ 1847560*x**10 + 1511640*x**11 + 1007760*x**12 + 542640*x**13
+ 232560*x**14 + 77520*x**15 + 19380*x**16 + 3420*x**17 + 380*x**18
+ 20*x**19)
assert factor(dep) == 20*(1 + x)**19
def test_H15():
assert simplify((Mul(*[x - r for r in solveset(x**3 + x**2 - 7)]))) == x**3 + x**2 - 7
def test_H16():
assert factor(x**100 - 1) == ((x - 1)*(x + 1)*(x**2 + 1)*(x**4 - x**3
+ x**2 - x + 1)*(x**4 + x**3 + x**2 + x + 1)*(x**8 - x**6 + x**4
- x**2 + 1)*(x**20 - x**15 + x**10 - x**5 + 1)*(x**20 + x**15 + x**10
+ x**5 + 1)*(x**40 - x**30 + x**20 - x**10 + 1))
def test_H17():
assert simplify(factor(expand(p1 * p2)) - p1*p2) == 0
@XFAIL
def test_H18():
# Factor over complex rationals.
test = factor(4*x**4 + 8*x**3 + 77*x**2 + 18*x + 153)
good = (2*x + 3*I)*(2*x - 3*I)*(x + 1 - 4*I)*(x + 1 + 4*I)
assert test == good
def test_H19():
a = symbols('a')
# The idea is to let a**2 == 2, then solve 1/(a-1). Answer is a+1")
assert Poly(a - 1).invert(Poly(a**2 - 2)) == a + 1
@XFAIL
def test_H20():
raise NotImplementedError("let a**2==2; (x**3 + (a-2)*x**2 - "
+ "(2*a+3)*x - 3*a) / (x**2-2) = (x**2 - 2*x - 3) / (x-a)")
@XFAIL
def test_H21():
raise NotImplementedError("evaluate (b+c)**4 assuming b**3==2, c**2==3. \
Answer is 2*b + 8*c + 18*b**2 + 12*b*c + 9")
def test_H22():
assert factor(x**4 - 3*x**2 + 1, modulus=5) == (x - 2)**2 * (x + 2)**2
def test_H23():
f = x**11 + x + 1
g = (x**2 + x + 1) * (x**9 - x**8 + x**6 - x**5 + x**3 - x**2 + 1)
assert factor(f, modulus=65537) == g
def test_H24():
phi = AlgebraicNumber(S.GoldenRatio.expand(func=True), alias='phi')
assert factor(x**4 - 3*x**2 + 1, extension=phi) == \
(x - phi)*(x + 1 - phi)*(x - 1 + phi)*(x + phi)
def test_H25():
e = (x - 2*y**2 + 3*z**3) ** 20
assert factor(expand(e)) == e
@slow
def test_H26():
g = expand((sin(x) - 2*cos(y)**2 + 3*tan(z)**3)**20)
assert factor(g, expand=False) == (-sin(x) + 2*cos(y)**2 - 3*tan(z)**3)**20
@slow
def test_H27():
f = 24*x*y**19*z**8 - 47*x**17*y**5*z**8 + 6*x**15*y**9*z**2 - 3*x**22 + 5
g = 34*x**5*y**8*z**13 + 20*x**7*y**7*z**7 + 12*x**9*y**16*z**4 + 80*y**14*z
h = -2*z*y**7 \
*(6*x**9*y**9*z**3 + 10*x**7*z**6 + 17*y*x**5*z**12 + 40*y**7) \
*(3*x**22 + 47*x**17*y**5*z**8 - 6*x**15*y**9*z**2 - 24*x*y**19*z**8 - 5)
assert factor(expand(f*g)) == h
@XFAIL
def test_H28():
raise NotImplementedError("expand ((1 - c**2)**5 * (1 - s**2)**5 * "
+ "(c**2 + s**2)**10) with c**2 + s**2 = 1. Answer is c**10*s**10.")
@XFAIL
def test_H29():
assert factor(4*x**2 - 21*x*y + 20*y**2, modulus=3) == (x + y)*(x - y)
def test_H30():
test = factor(x**3 + y**3, extension=sqrt(-3))
answer = (x + y)*(x + y*(-R(1, 2) - sqrt(3)/2*I))*(x + y*(-R(1, 2) + sqrt(3)/2*I))
assert answer == test
def test_H31():
f = (x**2 + 2*x + 3)/(x**3 + 4*x**2 + 5*x + 2)
g = 2 / (x + 1)**2 - 2 / (x + 1) + 3 / (x + 2)
assert apart(f) == g
@XFAIL
def test_H32(): # issue 6558
raise NotImplementedError("[A*B*C - (A*B*C)**(-1)]*A*C*B (product \
of a non-commuting product and its inverse)")
def test_H33():
A, B, C = symbols('A, B, C', commutative=False)
assert (Commutator(A, Commutator(B, C))
+ Commutator(B, Commutator(C, A))
+ Commutator(C, Commutator(A, B))).doit().expand() == 0
# I. Trigonometry
@XFAIL
def test_I1():
assert tan(7*pi/10) == -sqrt(1 + 2/sqrt(5))
@XFAIL
def test_I2():
assert sqrt((1 + cos(6))/2) == -cos(3)
def test_I3():
assert cos(n*pi) + sin((4*n - 1)*pi/2) == (-1)**n - 1
def test_I4():
assert refine(cos(pi*cos(n*pi)) + sin(pi/2*cos(n*pi)), Q.integer(n)) == (-1)**n - 1
@XFAIL
def test_I5():
assert sin((n**5/5 + n**4/2 + n**3/3 - n/30) * pi) == 0
@XFAIL
def test_I6():
raise NotImplementedError("assuming -3*pi<x<-5*pi/2, abs(cos(x)) == -cos(x), abs(sin(x)) == -sin(x)")
@XFAIL
def test_I7():
assert cos(3*x)/cos(x) == cos(x)**2 - 3*sin(x)**2
@XFAIL
def test_I8():
assert cos(3*x)/cos(x) == 2*cos(2*x) - 1
@XFAIL
def test_I9():
# Supposed to do this with rewrite rules.
assert cos(3*x)/cos(x) == cos(x)**2 - 3*sin(x)**2
def test_I10():
assert trigsimp((tan(x)**2 + 1 - cos(x)**-2) / (sin(x)**2 + cos(x)**2 - 1)) == nan
@SKIP("hangs")
@XFAIL
def test_I11():
assert limit((tan(x)**2 + 1 - cos(x)**-2) / (sin(x)**2 + cos(x)**2 - 1), x, 0) != 0
@XFAIL
def test_I12():
try:
# This should fail or return nan or something.
diff((tan(x)**2 + 1 - cos(x)**-2) / (sin(x)**2 + cos(x)**2 - 1), x)
except:
assert True
else:
assert False, "taking the derivative with a fraction equivalent to 0/0 should fail"
# J. Special functions.
def test_J1():
assert bernoulli(16) == R(-3617, 510)
def test_J2():
assert diff(elliptic_e(x, y**2), y) == (elliptic_e(x, y**2) - elliptic_f(x, y**2))/y
@XFAIL
def test_J3():
raise NotImplementedError("Jacobi elliptic functions: diff(dn(u,k), u) == -k**2*sn(u,k)*cn(u,k)")
def test_J4():
assert gamma(R(-1, 2)) == -2*sqrt(pi)
def test_J5():
assert polygamma(0, R(1, 3)) == -log(3) - sqrt(3)*pi/6 - EulerGamma - log(sqrt(3))
def test_J6():
assert mpmath.besselj(2, 1 + 1j).ae(mpc('0.04157988694396212', '0.24739764151330632'))
def test_J7():
assert simplify(besselj(R(-5,2), pi/2)) == 12/(pi**2)
def test_J8():
p = besselj(R(3,2), z)
q = (sin(z)/z - cos(z))/sqrt(pi*z/2)
assert simplify(expand_func(p) -q) == 0
def test_J9():
assert besselj(0, z).diff(z) == - besselj(1, z)
def test_J10():
mu, nu = symbols('mu, nu', integer=True)
assert assoc_legendre(nu, mu, 0) == 2**mu*sqrt(pi)/gamma((nu - mu)/2 + 1)/gamma((-nu - mu + 1)/2)
def test_J11():
assert simplify(assoc_legendre(3, 1, x)) == simplify(-R(3, 2)*sqrt(1 - x**2)*(5*x**2 - 1))
@slow
def test_J12():
assert simplify(chebyshevt(1008, x) - 2*x*chebyshevt(1007, x) + chebyshevt(1006, x)) == 0
def test_J13():
a = symbols('a', integer=True, negative=False)
assert chebyshevt(a, -1) == (-1)**a
def test_J14():
p = hyper([S(1)/2, S(1)/2], [S(3)/2], z**2)
assert hyperexpand(p) == asin(z)/z
@XFAIL
def test_J15():
raise NotImplementedError("F((n+2)/2,-(n-2)/2,R(3,2),sin(z)**2) == sin(n*z)/(n*sin(z)*cos(z)); F(.) is hypergeometric function")
@XFAIL
def test_J16():
raise NotImplementedError("diff(zeta(x), x) @ x=0 == -log(2*pi)/2")
def test_J17():
assert integrate(f((x + 2)/5)*DiracDelta((x - 2)/3) - g(x)*diff(DiracDelta(x - 1), x), (x, 0, 3)) == 3*f(S(4)/5) + Subs(Derivative(g(x), x), x, 1)
@XFAIL
def test_J18():
raise NotImplementedError("define an antisymmetric function")
# K. The Complex Domain
def test_K1():
z1, z2 = symbols('z1, z2', complex=True)
assert re(z1 + I*z2) == -im(z2) + re(z1)
assert im(z1 + I*z2) == im(z1) + re(z2)
def test_K2():
assert abs(3 - sqrt(7) + I*sqrt(6*sqrt(7) - 15)) == 1
@XFAIL
def test_K3():
a, b = symbols('a, b', real=True)
assert simplify(abs(1/(a + I/a + I*b))) == 1/sqrt(a**2 + (I/a + b)**2)
def test_K4():
assert log(3 + 4*I).expand(complex=True) == log(5) + I*atan(R(4, 3))
def test_K5():
x, y = symbols('x, y', real=True)
assert tan(x + I*y).expand(complex=True) == (sin(2*x)/(cos(2*x) +
cosh(2*y)) + I*sinh(2*y)/(cos(2*x) + cosh(2*y)))
def test_K6():
assert sqrt(x*y*abs(z)**2)/(sqrt(x)*abs(z)) == sqrt(x*y)/sqrt(x)
assert sqrt(x*y*abs(z)**2)/(sqrt(x)*abs(z)) != sqrt(y)
def test_K7():
y = symbols('y', real=True, negative=False)
expr = sqrt(x*y*abs(z)**2)/(sqrt(x)*abs(z))
sexpr = simplify(expr)
assert sexpr == sqrt(y)
@XFAIL
def test_K8():
z = symbols('z', complex=True)
assert simplify(sqrt(1/z) - 1/sqrt(z)) != 0 # Passes
z = symbols('z', complex=True, negative=False)
assert simplify(sqrt(1/z) - 1/sqrt(z)) == 0 # Fails
def test_K9():
z = symbols('z', real=True, positive=True)
assert simplify(sqrt(1/z) - 1/sqrt(z)) == 0
def test_K10():
z = symbols('z', real=True, negative=True)
assert simplify(sqrt(1/z) + 1/sqrt(z)) == 0
# This goes up to K25
# L. Determining Zero Equivalence
def test_L1():
assert sqrt(997) - (997**3)**R(1, 6) == 0
def test_L2():
assert sqrt(999983) - (999983**3)**R(1, 6) == 0
def test_L3():
assert simplify((2**R(1, 3) + 4**R(1, 3))**3 - 6*(2**R(1, 3) + 4**R(1, 3)) - 6) == 0
def test_L4():
assert trigsimp(cos(x)**3 + cos(x)*sin(x)**2 - cos(x)) == 0
@XFAIL
def test_L5():
assert log(tan(R(1, 2)*x + pi/4)) - asinh(tan(x)) == 0
def test_L6():
assert (log(tan(x/2 + pi/4)) - asinh(tan(x))).diff(x).subs({x: 0}) == 0
@XFAIL
def test_L7():
assert simplify(log((2*sqrt(x) + 1)/(sqrt(4*x + 4*sqrt(x) + 1)))) == 0
@XFAIL
def test_L8():
assert simplify((4*x + 4*sqrt(x) + 1)**(sqrt(x)/(2*sqrt(x) + 1)) \
*(2*sqrt(x) + 1)**(1/(2*sqrt(x) + 1)) - 2*sqrt(x) - 1) == 0
@XFAIL
def test_L9():
z = symbols('z', complex=True)
assert simplify(2**(1 - z)*gamma(z)*zeta(z)*cos(z*pi/2) - pi**2*zeta(1 - z)) == 0
# M. Equations
@XFAIL
def test_M1():
assert Equality(x, 2)/2 + Equality(1, 1) == Equality(x/2 + 1, 2)
def test_M2():
# The roots of this equation should all be real. Note that this
# doesn't test that they are correct.
sol = solveset(3*x**3 - 18*x**2 + 33*x - 19, x)
assert all(s.expand(complex=True).is_real for s in sol)
@XFAIL
def test_M5():
assert solveset(x**6 - 9*x**4 - 4*x**3 + 27*x**2 - 36*x - 23, x) == FiniteSet(2**(1/3) + sqrt(3), 2**(1/3) - sqrt(3), +sqrt(3) - 1/2**(2/3) + I*sqrt(3)/2**(2/3), +sqrt(3) - 1/2**(2/3) - I*sqrt(3)/2**(2/3), -sqrt(3) - 1/2**(2/3) + I*sqrt(3)/2**(2/3), -sqrt(3) - 1/2**(2/3) - I*sqrt(3)/2**(2/3))
def test_M6():
assert set(solveset(x**7 - 1, x)) == \
{cos(n*2*pi/7) + I*sin(n*2*pi/7) for n in range(0, 7)}
# The paper asks for exp terms, but sin's and cos's may be acceptable;
# if the results are simplified, exp terms appear for all but
# -sin(pi/14) - I*cos(pi/14) and -sin(pi/14) + I*cos(pi/14) which
# will simplify if you apply the transformation foo.rewrite(exp).expand()
def test_M7():
# TODO: Replace solve with solveset, as of now test fails for solveset
sol = solve(x**8 - 8*x**7 + 34*x**6 - 92*x**5 + 175*x**4 - 236*x**3 +
226*x**2 - 140*x + 46, x)
assert [s.simplify() for s in sol] == [
1 - sqrt(-6 - 2*I*sqrt(3 + 4*sqrt(3)))/2,
1 + sqrt(-6 - 2*I*sqrt(3 + 4*sqrt(3)))/2,
1 - sqrt(-6 + 2*I*sqrt(3 + 4*sqrt(3)))/2,
1 + sqrt(-6 + 2*I*sqrt(3 + 4*sqrt (3)))/2,
1 - sqrt(-6 + 2*sqrt(-3 + 4*sqrt(3)))/2,
1 + sqrt(-6 + 2*sqrt(-3 + 4*sqrt(3)))/2,
1 - sqrt(-6 - 2*sqrt(-3 + 4*sqrt(3)))/2,
1 + sqrt(-6 - 2*sqrt(-3 + 4*sqrt(3)))/2]
@XFAIL # There are an infinite number of solutions.
def test_M8():
x = Symbol('x')
z = symbols('z', complex=True)
assert solveset(exp(2*x) + 2*exp(x) + 1 - z, x, S.Reals) == \
FiniteSet(log(1 + z - 2*sqrt(z))/2, log(1 + z + 2*sqrt(z))/2)
# This one could be simplified better (the 1/2 could be pulled into the log
# as a sqrt, and the function inside the log can be factored as a square,
# giving [log(sqrt(z) - 1), log(sqrt(z) + 1)]). Also, there should be an
# infinite number of solutions.
# x = {log(sqrt(z) - 1), log(sqrt(z) + 1) + i pi} [+ n 2 pi i, + n 2 pi i]
# where n is an arbitrary integer. See url of detailed output above.
@XFAIL
def test_M9():
x = symbols('x')
raise NotImplementedError("solveset(exp(2-x**2)-exp(-x),x) has complex solutions.")
def test_M10():
# TODO: Replace solve with solveset, as of now test fails for solveset
assert solve(exp(x) - x, x) == [-LambertW(-1)]
@XFAIL
def test_M11():
assert solveset(x**x - x, x) == FiniteSet(-1, 1)
def test_M12():
# TODO: x = [-1, 2*(+/-asinh(1)*I + n*pi}, 3*(pi/6 + n*pi/3)]
# TODO: Replace solve with solveset, as of now test fails for solveset
assert solve((x + 1)*(sin(x)**2 + 1)**2*cos(3*x)**3, x) == [
-1, pi/6, pi/2,
- I*log(1 + sqrt(2)), I*log(1 + sqrt(2)),
pi - I*log(1 + sqrt(2)), pi + I*log(1 + sqrt(2)),
]
@XFAIL
def test_M13():
n = Dummy('n')
assert solveset_real(sin(x) - cos(x), x) == ImageSet(Lambda(n, n*pi - 7*pi/4), S.Integers)
@XFAIL
def test_M14():
n = Dummy('n')
assert solveset_real(tan(x) - 1, x) == ImageSet(Lambda(n, n*pi + pi/4), S.Integers)
@XFAIL
def test_M15():
n = Dummy('n')
assert solveset(sin(x) - S.Half) == Union(ImageSet(Lambda(n, 2*n*pi + pi/6), S.Integers),
ImageSet(Lambda(n, 2*n*pi + 5*pi/6), S.Integers))
@XFAIL
def test_M16():
n = Dummy('n')
assert solveset(sin(x) - tan(x), x) == ImageSet(Lambda(n, n*pi), Integers())
@XFAIL
def test_M17():
assert solveset_real(asin(x) - atan(x), x) == FiniteSet(0)
@XFAIL
def test_M18():
assert solveset_real(acos(x) - atan(x), x) == FiniteSet(sqrt((sqrt(5) - 1)/2))
def test_M19():
# TODO: Replace solve with solveset, as of now test fails for solveset
assert solve((x - 2)/x**R(1, 3), x) == [2]
def test_M20():
assert solveset(sqrt(x**2 + 1) - x + 2, x) == EmptySet()
def test_M21():
assert solveset(x + sqrt(x) - 2) == FiniteSet(1)
def test_M22():
assert solveset(2*sqrt(x) + 3*x**R(1, 4) - 2) == FiniteSet(R(1, 16))
def test_M23():
x = symbols('x', complex=True)
# TODO: Replace solve with solveset, as of now test fails for solveset
assert solve(x - 1/sqrt(1 + x**2)) == [
-I*sqrt(S.Half + sqrt(5)/2), sqrt(-S.Half + sqrt(5)/2)]
def test_M24():
# TODO: Replace solve with solveset, as of now test fails for solveset
solution = solve(1 - binomial(m, 2)*2**k, k)
answer = log(2/(m*(m - 1)), 2)
assert solution[0].expand() == answer.expand()
def test_M25():
a, b, c, d = symbols(':d', positive=True)
x = symbols('x')
# TODO: Replace solve with solveset, as of now test fails for solveset
assert solve(a*b**x - c*d**x, x)[0].expand() == (log(c/a)/log(b/d)).expand()
def test_M26():
# TODO: Replace solve with solveset, as of now test fails for solveset
assert solve(sqrt(log(x)) - log(sqrt(x))) == [1, exp(4)]
@XFAIL
def test_M27():
x = symbols('x', real=True)
b = symbols('b', real=True)
with assuming(Q.is_true(sin(cos(1/E**2) + 1) + b > 0)):
# TODO: Replace solve with solveset
solve(log(acos(asin(x**R(2, 3) - b) - 1)) + 2, x) == [-b - sin(1 + cos(1/e**2))**R(3/2), b + sin(1 + cos(1/e**2))**R(3/2)]
@XFAIL
def test_M28():
# TODO: Replace solve with solveset, as of now
# solveset doesn't supports assumptions
assert solve(5*x + exp((x - 5)/2) - 8*x**3, x, assume=Q.real(x)) == [-0.784966, -0.016291, 0.802557]
def test_M29():
x = symbols('x')
assert solveset(abs(x - 1) - 2, domain=S.Reals) == FiniteSet(-1, 3)
@XFAIL
def test_M30():
# TODO: Replace solve with solveset, as of now
# solveset doesn't supports assumptions
assert solve(abs(2*x + 5) - abs(x - 2),x, assume=Q.real(x)) == [-1, -7]
@XFAIL
def test_M31():
# TODO: Replace solve with solveset, as of now
# solveset doesn't supports assumptions
assert solve(1 - abs(x) - max(-x - 2, x - 2),x, assume=Q.real(x)) == [-3/2, 3/2]
@XFAIL
def test_M32():
# TODO: Replace solve with solveset, as of now
# solveset doesn't supports assumptions
assert solve(max(2 - x**2, x)- max(-x, (x**3)/9), assume=Q.real(x)) == [-1, 3]
@XFAIL
def test_M33():
# TODO: Replace solve with solveset, as of now
# solveset doesn't supports assumptions
# Second answer can be written in another form. The second answer is the root of x**3 + 9*x**2 - 18 = 0 in the interval (-2, -1).
assert solve(max(2 - x**2, x) - x**3/9, assume=Q.real(x)) == [-3, -1.554894, 3]
@XFAIL
def test_M34():
z = symbols('z', complex=True)
assert solveset((1 + I) * z + (2 - I) * conjugate(z) + 3*I, z) == FiniteSet(2 + 3*I)
def test_M35():
x, y = symbols('x y', real=True)
assert linsolve((3*x - 2*y - I*y + 3*I).as_real_imag(), y, x) == FiniteSet((3, 2))
@XFAIL
def test_M36():
# TODO: Replace solve with solveset, as of now
# solveset doesn't supports solving for function
assert solve(f**2 + f - 2, x) == [Eq(f(x), 1), Eq(f(x), -2)]
def test_M37():
assert linsolve([x + y + z - 6, 2*x + y + 2*z - 10, x + 3*y + z - 10 ], x, y, z) == \
FiniteSet((-z + 4, 2, z))
def test_M38():
variables = vring("k1:50", vfield("a,b,c", ZZ).to_domain())
system = [
-b*k8/a + c*k8/a, -b*k11/a + c*k11/a, -b*k10/a + c*k10/a + k2, -k3 - b*k9/a + c*k9/a,
-b*k14/a + c*k14/a, -b*k15/a + c*k15/a, -b*k18/a + c*k18/a - k2, -b*k17/a + c*k17/a,
-b*k16/a + c*k16/a + k4, -b*k13/a + c*k13/a - b*k21/a + c*k21/a + b*k5/a - c*k5/a,
b*k44/a - c*k44/a, -b*k45/a + c*k45/a, -b*k20/a + c*k20/a, -b*k44/a + c*k44/a,
b*k46/a - c*k46/a, b**2*k47/a**2 - 2*b*c*k47/a**2 + c**2*k47/a**2, k3, -k4,
-b*k12/a + c*k12/a - a*k6/b + c*k6/b, -b*k19/a + c*k19/a + a*k7/c - b*k7/c,
b*k45/a - c*k45/a, -b*k46/a + c*k46/a, -k48 + c*k48/a + c*k48/b - c**2*k48/(a*b),
-k49 + b*k49/a + b*k49/c - b**2*k49/(a*c), a*k1/b - c*k1/b, a*k4/b - c*k4/b,
a*k3/b - c*k3/b + k9, -k10 + a*k2/b - c*k2/b, a*k7/b - c*k7/b, -k9, k11,
b*k12/a - c*k12/a + a*k6/b - c*k6/b, a*k15/b - c*k15/b, k10 + a*k18/b - c*k18/b,
-k11 + a*k17/b - c*k17/b, a*k16/b - c*k16/b, -a*k13/b + c*k13/b + a*k21/b - c*k21/b + a*k5/b - c*k5/b,
-a*k44/b + c*k44/b, a*k45/b - c*k45/b, a*k14/c - b*k14/c + a*k20/b - c*k20/b,
a*k44/b - c*k44/b, -a*k46/b + c*k46/b, -k47 + c*k47/a + c*k47/b - c**2*k47/(a*b),
a*k19/b - c*k19/b, -a*k45/b + c*k45/b, a*k46/b - c*k46/b, a**2*k48/b**2 - 2*a*c*k48/b**2 + c**2*k48/b**2,
-k49 + a*k49/b + a*k49/c - a**2*k49/(b*c), k16, -k17, -a*k1/c + b*k1/c,
-k16 - a*k4/c + b*k4/c, -a*k3/c + b*k3/c, k18 - a*k2/c + b*k2/c, b*k19/a - c*k19/a - a*k7/c + b*k7/c,
-a*k6/c + b*k6/c, -a*k8/c + b*k8/c, -a*k11/c + b*k11/c + k17, -a*k10/c + b*k10/c - k18,
-a*k9/c + b*k9/c, -a*k14/c + b*k14/c - a*k20/b + c*k20/b, -a*k13/c + b*k13/c + a*k21/c - b*k21/c - a*k5/c + b*k5/c,
a*k44/c - b*k44/c, -a*k45/c + b*k45/c, -a*k44/c + b*k44/c, a*k46/c - b*k46/c,
-k47 + b*k47/a + b*k47/c - b**2*k47/(a*c), -a*k12/c + b*k12/c, a*k45/c - b*k45/c,
-a*k46/c + b*k46/c, -k48 + a*k48/b + a*k48/c - a**2*k48/(b*c),
a**2*k49/c**2 - 2*a*b*k49/c**2 + b**2*k49/c**2, k8, k11, -k15, k10 - k18,
-k17, k9, -k16, -k29, k14 - k32, -k21 + k23 - k31, -k24 - k30, -k35, k44,
-k45, k36, k13 - k23 + k39, -k20 + k38, k25 + k37, b*k26/a - c*k26/a - k34 + k42,
-2*k44, k45, k46, b*k47/a - c*k47/a, k41, k44, -k46, -b*k47/a + c*k47/a,
k12 + k24, -k19 - k25, -a*k27/b + c*k27/b - k33, k45, -k46, -a*k48/b + c*k48/b,
a*k28/c - b*k28/c + k40, -k45, k46, a*k48/b - c*k48/b, a*k49/c - b*k49/c,
-a*k49/c + b*k49/c, -k1, -k4, -k3, k15, k18 - k2, k17, k16, k22, k25 - k7,
k24 + k30, k21 + k23 - k31, k28, -k44, k45, -k30 - k6, k20 + k32, k27 + b*k33/a - c*k33/a,
k44, -k46, -b*k47/a + c*k47/a, -k36, k31 - k39 - k5, -k32 - k38, k19 - k37,
k26 - a*k34/b + c*k34/b - k42, k44, -2*k45, k46, a*k48/b - c*k48/b,
a*k35/c - b*k35/c - k41, -k44, k46, b*k47/a - c*k47/a, -a*k49/c + b*k49/c,
-k40, k45, -k46, -a*k48/b + c*k48/b, a*k49/c - b*k49/c, k1, k4, k3, -k8,
-k11, -k10 + k2, -k9, k37 + k7, -k14 - k38, -k22, -k25 - k37, -k24 + k6,
-k13 - k23 + k39, -k28 + b*k40/a - c*k40/a, k44, -k45, -k27, -k44, k46,
b*k47/a - c*k47/a, k29, k32 + k38, k31 - k39 + k5, -k12 + k30, k35 - a*k41/b + c*k41/b,
-k44, k45, -k26 + k34 + a*k42/c - b*k42/c, k44, k45, -2*k46, -b*k47/a + c*k47/a,
-a*k48/b + c*k48/b, a*k49/c - b*k49/c, k33, -k45, k46, a*k48/b - c*k48/b,
-a*k49/c + b*k49/c
]
solution = {
k49: 0, k48: 0, k47: 0, k46: 0, k45: 0, k44: 0, k41: 0, k40: 0,
k38: 0, k37: 0, k36: 0, k35: 0, k33: 0, k32: 0, k30: 0, k29: 0,
k28: 0, k27: 0, k25: 0, k24: 0, k22: 0, k21: 0, k20: 0, k19: 0,
k18: 0, k17: 0, k16: 0, k15: 0, k14: 0, k13: 0, k12: 0, k11: 0,
k10: 0, k9: 0, k8: 0, k7: 0, k6: 0, k5: 0, k4: 0, k3: 0,
k2: 0, k1: 0,
k34: b/c*k42, k31: k39, k26: a/c*k42, k23: k39
}
assert solve_lin_sys(system, variables) == solution
def test_M39():
x, y, z = symbols('x y z', complex=True)
# TODO: Replace solve with solveset, as of now
# solveset doesn't supports non-linear multivariate
assert solve([x**2*y + 3*y*z - 4, -3*x**2*z + 2*y**2 + 1, 2*y*z**2 - z**2 - 1 ]) ==\
[{y: 1, z: 1, x: -1}, {y: 1, z: 1, x: 1},\
{y: sqrt(2)*I, z: R(1,3) - sqrt(2)*I/3, x: -sqrt(-1 - sqrt(2)*I)},\
{y: sqrt(2)*I, z: R(1,3) - sqrt(2)*I/3, x: sqrt(-1 - sqrt(2)*I)},\
{y: -sqrt(2)*I, z: R(1,3) + sqrt(2)*I/3, x: -sqrt(-1 + sqrt(2)*I)},\
{y: -sqrt(2)*I, z: R(1,3) + sqrt(2)*I/3, x: sqrt(-1 + sqrt(2)*I)}]
# N. Inequalities
def test_N1():
assert ask(Q.is_true(E**pi > pi**E))
@XFAIL
def test_N2():
x = symbols('x', real=True)
assert ask(Q.is_true(x**4 - x + 1 > 0)) is True
assert ask(Q.is_true(x**4 - x + 1 > 1)) is False
@XFAIL
def test_N3():
x = symbols('x', real=True)
assert ask(Q.is_true(And(Lt(-1, x), Lt(x, 1))), Q.is_true(abs(x) < 1 ))
@XFAIL
def test_N4():
x, y = symbols('x y', real=True)
assert ask(Q.is_true(2*x**2 > 2*y**2), Q.is_true((x > y) & (y > 0))) is True
@XFAIL
def test_N5():
x, y, k = symbols('x y k', real=True)
assert ask(Q.is_true(k*x**2 > k*y**2), Q.is_true((x > y) & (y > 0) & (k > 0))) is True
@XFAIL
def test_N6():
x, y, k, n = symbols('x y k n', real=True)
assert ask(Q.is_true(k*x**n > k*y**n), Q.is_true((x > y) & (y > 0) & (k > 0) & (n > 0))) is True
@XFAIL
def test_N7():
x, y = symbols('x y', real=True)
assert ask(Q.is_true(y > 0), Q.is_true((x > 1) & (y >= x - 1))) is True
@XFAIL
def test_N8():
x, y, z = symbols('x y z', real=True)
assert ask(Q.is_true((x == y) & (y == z)),
Q.is_true((x >= y) & (y >= z) & (z >= x)))
def test_N9():
x = Symbol('x')
assert solveset(abs(x - 1) > 2, domain=S.Reals) == Union(Interval(-oo, -1, False, True),
Interval(3, oo, True))
def test_N10():
x = Symbol('x')
p = (x - 1)*(x - 2)*(x - 3)*(x - 4)*(x - 5)
assert solveset(expand(p) < 0, domain=S.Reals) == Union(Interval(-oo, 1, True, True),
Interval(2, 3, True, True),
Interval(4, 5, True, True))
def test_N11():
x = Symbol('x')
assert solveset(6/(x - 3) <= 3, domain=S.Reals) == Union(Interval(-oo, 3, True, True), Interval(5, oo))
def test_N12():
x = Symbol('x')
assert solveset(sqrt(x) < 2, domain=S.Reals) == Interval(0, 4, False, True)
def test_N13():
x = Symbol('x')
assert solveset(sin(x) < 2, domain=S.Reals) == S.Reals
@XFAIL
def test_N14():
# raises NotImplementedError: can't reduce [sin(x) < 1]
x = Symbol('x')
assert solveset(sin(x) < 1, domain=S.Reals) == Union(Interval(-oo, pi/2, True, True),
Interval(pi/2, oo, True, True))
def test_N15():
r, t = symbols('r t')
# raises NotImplementedError: only univariate inequalities are supported
solveset(abs(2*r*(cos(t) - 1) + 1) <= 1, r, S.Reals)
def test_N16():
r, t = symbols('r t')
solveset((r**2)*((cos(t) - 4)**2)*sin(t)**2 < 9, r, S.Reals)
@XFAIL
def test_N17():
# currently only univariate inequalities are supported
assert solveset((x + y > 0, x - y < 0), (x, y)) == (abs(x) < y)
def test_O1():
M = Matrix((1 + I, -2, 3*I))
assert sqrt(expand(M.dot(M.H))) == sqrt(15)
def test_O2():
assert Matrix((2, 2, -3)).cross(Matrix((1, 3, 1))) == Matrix([[11],
[-5],
[4]])
# The vector module has no way of representing vectors symbolically (without
# respect to a basis)
@XFAIL
def test_O3():
assert (va ^ vb) | (vc ^ vd) == -(va | vc)*(vb | vd) + (va | vd)*(vb | vc)
def test_O4():
from sympy.vector import CoordSys3D, Del
N = CoordSys3D("N")
delop = Del()
i, j, k = N.base_vectors()
x, y, z = N.base_scalars()
F = i*(x*y*z) + j*((x*y*z)**2) + k*((y**2)*(z**3))
assert delop.cross(F).doit() == (-2*x**2*y**2*z + 2*y*z**3)*i + x*y*j + (2*x*y**2*z**2 - x*z)*k
# The vector module has no way of representing vectors symbolically (without
# respect to a basis)
@XFAIL
def test_O5():
assert grad|(f^g)-g|(grad^f)+f|(grad^g) == 0
#testO8-O9 MISSING!!
def test_O10():
L = [Matrix([2, 3, 5]), Matrix([3, 6, 2]), Matrix([8, 3, 6])]
assert GramSchmidt(L) == [Matrix([
[2],
[3],
[5]]),
Matrix([
[S(23)/19],
[S(63)/19],
[S(-47)/19]]),
Matrix([
[S(1692)/353],
[S(-1551)/706],
[S(-423)/706]])]
@XFAIL
def test_P1():
raise NotImplementedError("Matrix property/function to extract Nth \
diagonal not implemented. See Matlab diag(A,k) \
http://www.mathworks.de/de/help/symbolic/diag.html")
def test_P2():
M = Matrix([[1, 2, 3], [4, 5, 6], [7, 8, 9]])
M.row_del(1)
M.col_del(2)
assert M == Matrix([[1, 2],
[7, 8]])
@XFAIL
def test_P3():
A = Matrix([
[11, 12, 13, 14],
[21, 22, 23, 24],
[31, 32, 33, 34],
[41, 42, 43, 44]])
A11 = A[0:3, 1:4]
A12 = A[(0, 1, 3), (2, 0, 3)] # unsupported raises exception
A21 = A
A221 = A[0:2, 2:4]
A222 = A[(3, 0), (2, 1)] # unsupported raises exception
A22 = BlockMatrix([A221, A222])
B = BlockMatrix([[A11, A12],
[A21, A22]])
assert B == Matrix([[12, 13, 14, 13, 11, 14],
[22, 22, 24, 23, 21, 24],
[32, 33, 34, 43, 41, 44],
[11, 12, 13, 14, 13, 14],
[21, 22, 23, 24, 23, 24],
[31, 32, 33, 34, 43, 42],
[41, 42, 43, 44, 13, 12]])
@XFAIL
def test_P4():
raise NotImplementedError("Block matrix diagonalization not supported")
@XFAIL
def test_P5():
M = Matrix([[7, 11],
[3, 8]])
# Raises exception % not supported for matrices
assert M % 2 == Matrix([[1, 1],
[1, 0]])
def test_P5_workaround():
M = Matrix([[7, 11],
[3, 8]])
assert M.applyfunc(lambda i: i % 2) == Matrix([[1, 1],
[1, 0]])
def test_P6():
M = Matrix([[cos(x), sin(x)],
[-sin(x), cos(x)]])
assert M.diff(x, 2) == Matrix([[-cos(x), -sin(x)],
[sin(x), -cos(x)]])
def test_P7():
M = Matrix([[x, y]])*(
z*Matrix([[1, 3, 5],
[2, 4, 6]]) + Matrix([[7, -9, 11],
[-8, 10, -12]]))
assert M == Matrix([[x*(z + 7) + y*(2*z - 8), x*(3*z - 9) + y*(4*z + 10),
x*(5*z + 11) + y*(6*z - 12)]])
def test_P8():
M = Matrix([[1, -2*I],
[-3*I, 4]])
assert M.norm(ord=S.Infinity) == 7
def test_P9():
a, b, c = symbols('a b c', real=True)
M = Matrix([[a/(b*c), 1/c, 1/b],
[1/c, b/(a*c), 1/a],
[1/b, 1/a, c/(a*b)]])
assert factor(M.norm('fro')) == (a**2 + b**2 + c**2)/(abs(a)*abs(b)*abs(c))
@XFAIL
def test_P10():
M = Matrix([[1, 2 + 3*I],
[f(4 - 5*i), 6]])
# conjugate(f(4 - 5*i)) is not simplified to f(4+5*I)
assert M.H == Matrix([[1, f(4 + 5*I)],
[2 + 3*I, 6]])
@XFAIL
def test_P11():
# raises NotImplementedError("Matrix([[x,y],[1,x*y]]).inv()
# not simplifying to extract common factor")
assert Matrix([[x, y],
[1, x*y]]).inv() == (1/(x**2 - 1))*Matrix([[x, -1],
[-1/y, x/y]])
def test_P12():
A11 = MatrixSymbol('A11', n, n)
A12 = MatrixSymbol('A12', n, n)
A22 = MatrixSymbol('A22', n, n)
B = BlockMatrix([[A11, A12],
[ZeroMatrix(n, n), A22]])
assert block_collapse(B.I) == BlockMatrix([[A11.I, (-1)*A11.I*A12*A22.I],
[ZeroMatrix(n, n), A22.I]])
def test_P13():
M = Matrix([[1, x - 2, x - 3],
[x - 1, x**2 - 3*x + 6, x**2 - 3*x - 2],
[x - 2, x**2 - 8, 2*(x**2) - 12*x + 14]])
L, U, _ = M.LUdecomposition()
assert simplify(L) == Matrix([[1, 0, 0],
[x - 1, 1, 0],
[x - 2, x - 3, 1]])
assert simplify(U) == Matrix([[1, x - 2, x - 3],
[0, 4, x - 5],
[0, 0, x - 7]])
def test_P14():
M = Matrix([[1, 2, 3, 1, 3],
[3, 2, 1, 1, 7],
[0, 2, 4, 1, 1],
[1, 1, 1, 1, 4]])
R, _ = M.rref()
assert R == Matrix([[1, 0, -1, 0, 2],
[0, 1, 2, 0, -1],
[0, 0, 0, 1, 3],
[0, 0, 0, 0, 0]])
def test_P15():
M = Matrix([[-1, 3, 7, -5],
[4, -2, 1, 3],
[2, 4, 15, -7]])
assert M.rank() == 2
def test_P16():
M = Matrix([[2*sqrt(2), 8],
[6*sqrt(6), 24*sqrt(3)]])
assert M.rank() == 1
def test_P17():
t = symbols('t', real=True)
M=Matrix([
[sin(2*t), cos(2*t)],
[2*(1 - (cos(t)**2))*cos(t), (1 - 2*(sin(t)**2))*sin(t)]])
assert M.rank() == 1
def test_P18():
M = Matrix([[1, 0, -2, 0],
[-2, 1, 0, 3],
[-1, 2, -6, 6]])
assert M.nullspace() == [Matrix([[2],
[4],
[1],
[0]]),
Matrix([[0],
[-3],
[0],
[1]])]
def test_P19():
w = symbols('w')
M = Matrix([[1, 1, 1, 1],
[w, x, y, z],
[w**2, x**2, y**2, z**2],
[w**3, x**3, y**3, z**3]])
assert M.det() == (w**3*x**2*y - w**3*x**2*z - w**3*x*y**2 + w**3*x*z**2
+ w**3*y**2*z - w**3*y*z**2 - w**2*x**3*y + w**2*x**3*z
+ w**2*x*y**3 - w**2*x*z**3 - w**2*y**3*z + w**2*y*z**3
+ w*x**3*y**2 - w*x**3*z**2 - w*x**2*y**3 + w*x**2*z**3
+ w*y**3*z**2 - w*y**2*z**3 - x**3*y**2*z + x**3*y*z**2
+ x**2*y**3*z - x**2*y*z**3 - x*y**3*z**2 + x*y**2*z**3
)
@XFAIL
def test_P20():
raise NotImplementedError("Matrix minimal polynomial not supported")
def test_P21():
M = Matrix([[5, -3, -7],
[-2, 1, 2],
[2, -3, -4]])
assert M.charpoly(x).as_expr() == x**3 - 2*x**2 - 5*x + 6
@slow
def test_P22():
# Wester test calculates eigenvalues for a diagonal matrix of dimension 100
# This currently takes forever with sympy:
# M = (2 - x)*eye(100);
# assert M.eigenvals() == {-x + 2: 100}
# So we will speed-up the test checking only for dimension=12
d = 12
M = (2 - x)*eye(d)
assert M.eigenvals() == {-x + 2: d}
def test_P23():
M = Matrix([
[2, 1, 0, 0, 0],
[1, 2, 1, 0, 0],
[0, 1, 2, 1, 0],
[0, 0, 1, 2, 1],
[0, 0, 0, 1, 2]])
assert M.eigenvals() == {
S('1'): 1,
S('2'): 1,
S('3'): 1,
S('sqrt(3) + 2'): 1,
S('-sqrt(3) + 2'): 1}
def test_P24():
M = Matrix([[611, 196, -192, 407, -8, -52, -49, 29],
[196, 899, 113, -192, -71, -43, -8, -44],
[-192, 113, 899, 196, 61, 49, 8, 52],
[ 407, -192, 196, 611, 8, 44, 59, -23],
[ -8, -71, 61, 8, 411, -599, 208, 208],
[ -52, -43, 49, 44, -599, 411, 208, 208],
[ -49, -8, 8, 59, 208, 208, 99, -911],
[ 29, -44, 52, -23, 208, 208, -911, 99]])
assert M.eigenvals() == {
S('0'): 1,
S('10*sqrt(10405)'): 1,
S('100*sqrt(26) + 510'): 1,
S('1000'): 2,
S('-100*sqrt(26) + 510'): 1,
S('-10*sqrt(10405)'): 1,
S('1020'): 1}
def test_P25():
MF = N(Matrix([[ 611, 196, -192, 407, -8, -52, -49, 29],
[ 196, 899, 113, -192, -71, -43, -8, -44],
[-192, 113, 899, 196, 61, 49, 8, 52],
[ 407, -192, 196, 611, 8, 44, 59, -23],
[ -8, -71, 61, 8, 411, -599, 208, 208],
[ -52, -43, 49, 44, -599, 411, 208, 208],
[ -49, -8, 8, 59, 208, 208, 99, -911],
[ 29, -44, 52, -23, 208, 208, -911, 99]]))
assert (Matrix(sorted(MF.eigenvals())) - Matrix(
[-1020.0490184299969, 0.0, 0.09804864072151699, 1000.0,
1019.9019513592784, 1020.0, 1020.0490184299969])).norm() < 1e-13
def test_P26():
a0, a1, a2, a3, a4 = symbols('a0 a1 a2 a3 a4')
M = Matrix([[-a4, -a3, -a2, -a1, -a0, 0, 0, 0, 0],
[ 1, 0, 0, 0, 0, 0, 0, 0, 0],
[ 0, 1, 0, 0, 0, 0, 0, 0, 0],
[ 0, 0, 1, 0, 0, 0, 0, 0, 0],
[ 0, 0, 0, 1, 0, 0, 0, 0, 0],
[ 0, 0, 0, 0, 0, -1, -1, 0, 0],
[ 0, 0, 0, 0, 0, 1, 0, 0, 0],
[ 0, 0, 0, 0, 0, 0, 1, -1, -1],
[ 0, 0, 0, 0, 0, 0, 0, 1, 0]])
assert M.eigenvals(error_when_incomplete=False) == {
S('-1/2 - sqrt(3)*I/2'): 2,
S('-1/2 + sqrt(3)*I/2'): 2}
def test_P27():
a = symbols('a')
M = Matrix([[a, 0, 0, 0, 0],
[0, 0, 0, 0, 1],
[0, 0, a, 0, 0],
[0, 0, 0, a, 0],
[0, -2, 0, 0, 2]])
assert M.eigenvects() == [(a, 3, [Matrix([[1],
[0],
[0],
[0],
[0]]),
Matrix([[0],
[0],
[1],
[0],
[0]]),
Matrix([[0],
[0],
[0],
[1],
[0]])]),
(1 - I, 1, [Matrix([[ 0],
[-1/(-1 + I)],
[ 0],
[ 0],
[ 1]])]),
(1 + I, 1, [Matrix([[ 0],
[-1/(-1 - I)],
[ 0],
[ 0],
[ 1]])])]
@XFAIL
def test_P28():
raise NotImplementedError("Generalized eigenvectors not supported \
https://github.com/sympy/sympy/issues/5293")
@XFAIL
def test_P29():
raise NotImplementedError("Generalized eigenvectors not supported \
https://github.com/sympy/sympy/issues/5293")
def test_P30():
M = Matrix([[1, 0, 0, 1, -1],
[0, 1, -2, 3, -3],
[0, 0, -1, 2, -2],
[1, -1, 1, 0, 1],
[1, -1, 1, -1, 2]])
_, J = M.jordan_form()
assert J == Matrix([[-1, 0, 0, 0, 0],
[0, 1, 1, 0, 0],
[0, 0, 1, 0, 0],
[0, 0, 0, 1, 1],
[0, 0, 0, 0, 1]])
@XFAIL
def test_P31():
raise NotImplementedError("Smith normal form not implemented")
def test_P32():
M = Matrix([[1, -2],
[2, 1]])
assert exp(M).rewrite(cos).simplify() == Matrix([[E*cos(2), -E*sin(2)],
[E*sin(2), E*cos(2)]])
def test_P33():
w, t = symbols('w t')
M = Matrix([[0, 1, 0, 0],
[0, 0, 0, 2*w],
[0, 0, 0, 1],
[0, -2*w, 3*w**2, 0]])
assert exp(M*t).rewrite(cos).expand() == Matrix([
[1, -3*t + 4*sin(t*w)/w, 6*t*w - 6*sin(t*w), -2*cos(t*w)/w + 2/w],
[0, 4*cos(t*w) - 3, -6*w*cos(t*w) + 6*w, 2*sin(t*w)],
[0, 2*cos(t*w)/w - 2/w, -3*cos(t*w) + 4, sin(t*w)/w],
[0, -2*sin(t*w), 3*w*sin(t*w), cos(t*w)]])
@XFAIL
def test_P34():
a, b, c = symbols('a b c', real=True)
M = Matrix([[a, 1, 0, 0, 0, 0],
[0, a, 0, 0, 0, 0],
[0, 0, b, 0, 0, 0],
[0, 0, 0, c, 1, 0],
[0, 0, 0, 0, c, 1],
[0, 0, 0, 0, 0, c]])
# raises exception, sin(M) not supported. exp(M*I) also not supported
# https://github.com/sympy/sympy/issues/6218
assert sin(M) == Matrix([[sin(a), cos(a), 0, 0, 0, 0],
[0, sin(a), 0, 0, 0, 0],
[0, 0, sin(b), 0, 0, 0],
[0, 0, 0, sin(c), cos(c), -sin(c)/2],
[0, 0, 0, 0, sin(c), cos(c)],
[0, 0, 0, 0, 0, sin(c)]])
@XFAIL
def test_P35():
M = pi/2*Matrix([[2, 1, 1],
[2, 3, 2],
[1, 1, 2]])
# raises exception, sin(M) not supported. exp(M*I) also not supported
# https://github.com/sympy/sympy/issues/6218
assert sin(M) == eye(3)
@XFAIL
def test_P36():
M = Matrix([[10, 7],
[7, 17]])
assert sqrt(M) == Matrix([[3, 1],
[1, 4]])
@XFAIL
def test_P37():
M = Matrix([[1, 1, 0],
[0, 1, 0],
[0, 0, 1]])
#raises NotImplementedError: Implemented only for diagonalizable matrices
M**Rational(1, 2)
@XFAIL
def test_P38():
M=Matrix([[0, 1, 0],
[0, 0, 0],
[0, 0, 0]])
#raises NotImplementedError: Implemented only for diagonalizable matrices
M**Rational(1,2)
@XFAIL
def test_P39():
'''
M=Matrix([
[1, 1],
[2, 2],
[3, 3]])
M.SVD()
'''
raise NotImplementedError("Singular value decomposition not implemented")
def test_P40():
r, t = symbols('r t', real=True)
M = Matrix([r*cos(t), r*sin(t)])
assert M.jacobian(Matrix([r, t])) == Matrix([[cos(t), -r*sin(t)],
[sin(t), r*cos(t)]])
def test_P41():
r, t = symbols('r t', real=True)
assert hessian(r**2*sin(t),(r,t)) == Matrix([[ 2*sin(t), 2*r*cos(t)],
[2*r*cos(t), -r**2*sin(t)]])
def test_P42():
assert wronskian([cos(x), sin(x)], x).simplify() == 1
def test_P43():
def __my_jacobian(M, Y):
return Matrix([M.diff(v).T for v in Y]).T
r, t = symbols('r t', real=True)
M = Matrix([r*cos(t), r*sin(t)])
assert __my_jacobian(M,[r,t]) == Matrix([[cos(t), -r*sin(t)],
[sin(t), r*cos(t)]])
def test_P44():
def __my_hessian(f, Y):
V = Matrix([diff(f, v) for v in Y])
return Matrix([V.T.diff(v) for v in Y])
r, t = symbols('r t', real=True)
assert __my_hessian(r**2*sin(t), (r, t)) == Matrix([
[ 2*sin(t), 2*r*cos(t)],
[2*r*cos(t), -r**2*sin(t)]])
def test_P45():
def __my_wronskian(Y, v):
M = Matrix([Matrix(Y).T.diff(x, n) for n in range(0, len(Y))])
return M.det()
assert __my_wronskian([cos(x), sin(x)], x).simplify() == 1
# Q1-Q6 Tensor tests missing
@XFAIL
def test_R1():
i, n = symbols('i n', integer=True, positive=True)
xn = MatrixSymbol('xn', n, 1)
Sm = Sum((xn[i, 0] - Sum(xn[j, 0], (j, 0, n - 1))/n)**2, (i, 0, n - 1))
# raises AttributeError: 'str' object has no attribute 'is_Piecewise'
Sm.doit()
@XFAIL
def test_R2():
m, b = symbols('m b')
i, n = symbols('i n', integer=True, positive=True)
xn = MatrixSymbol('xn', n, 1)
yn = MatrixSymbol('yn', n, 1)
f = Sum((yn[i, 0] - m*xn[i, 0] - b)**2, (i, 0, n - 1))
f1 = diff(f, m)
f2 = diff(f, b)
# raises TypeError: solveset() takes at most 2 arguments (3 given)
solveset((f1, f2), m, b, domain=S.Reals)
@XFAIL
def test_R3():
n, k = symbols('n k', integer=True, positive=True)
sk = ((-1)**k) * (binomial(2*n, k))**2
Sm = Sum(sk, (k, 1, oo))
T = Sm.doit()
T2 = T.combsimp()
# returns -((-1)**n*factorial(2*n)
# - (factorial(n))**2)*exp_polar(-I*pi)/(factorial(n))**2
assert T2 == (-1)**n*binomial(2*n, n)
@XFAIL
def test_R4():
# Macsyma indefinite sum test case:
#(c15) /* Check whether the full Gosper algorithm is implemented
# => 1/2^(n + 1) binomial(n, k - 1) */
#closedform(indefsum(binomial(n, k)/2^n - binomial(n + 1, k)/2^(n + 1), k));
#Time= 2690 msecs
# (- n + k - 1) binomial(n + 1, k)
#(d15) - --------------------------------
# n
# 2 2 (n + 1)
#
#(c16) factcomb(makefact(%));
#Time= 220 msecs
# n!
#(d16) ----------------
# n
# 2 k! 2 (n - k)!
# Might be possible after fixing https://github.com/sympy/sympy/pull/1879
raise NotImplementedError("Indefinite sum not supported")
@XFAIL
def test_R5():
a, b, c, n, k = symbols('a b c n k', integer=True, positive=True)
sk = ((-1)**k)*(binomial(a + b, a + k)
*binomial(b + c, b + k)*binomial(c + a, c + k))
Sm = Sum(sk, (k, 1, oo))
T = Sm.doit() # hypergeometric series not calculated
assert T == factorial(a+b+c)/(factorial(a)*factorial(b)*factorial(c))
@XFAIL
def test_R6():
n, k = symbols('n k', integer=True, positive=True)
gn = MatrixSymbol('gn', n + 1, 1)
Sm = Sum(gn[k, 0] - gn[k - 1, 0], (k, 1, n + 1))
# raises AttributeError: 'str' object has no attribute 'is_Piecewise'
assert Sm.doit() == -gn[0, 0] + gn[n + 1, 0]
def test_R7():
n, k = symbols('n k', integer=True, positive=True)
T = Sum(k**3,(k,1,n)).doit()
assert T.factor() == n**2*(n + 1)**2/4
@XFAIL
def test_R8():
n, k = symbols('n k', integer=True, positive=True)
Sm = Sum(k**2*binomial(n, k), (k, 1, n))
T = Sm.doit() #returns Piecewise function
# T.simplify() raisesAttributeError
assert T.combsimp() == n*(n + 1)*2**(n - 2)
def test_R9():
n, k = symbols('n k', integer=True, positive=True)
Sm = Sum(binomial(n, k - 1)/k, (k, 1, n + 1))
assert Sm.doit().simplify() == (2**(n + 1) - 1)/(n + 1)
@XFAIL
def test_R10():
n, m, r, k = symbols('n m r k', integer=True, positive=True)
Sm = Sum(binomial(n, k)*binomial(m, r - k), (k, 0, r))
T = Sm.doit()
T2 = T.combsimp().rewrite(factorial)
assert T2 == factorial(m + n)/(factorial(r)*factorial(m + n - r))
assert T2 == binomial(m + n, r).rewrite(factorial)
# rewrite(binomial) is not working.
# https://github.com/sympy/sympy/issues/7135
T3 = T2.rewrite(binomial)
assert T3 == binomial(m + n, r)
@XFAIL
def test_R11():
n, k = symbols('n k', integer=True, positive=True)
sk = binomial(n, k)*fibonacci(k)
Sm = Sum(sk, (k, 0, n))
T = Sm.doit()
# Fibonacci simplification not implemented
# https://github.com/sympy/sympy/issues/7134
assert T == fibonacci(2*n)
@XFAIL
def test_R12():
n, k = symbols('n k', integer=True, positive=True)
Sm = Sum(fibonacci(k)**2, (k, 0, n))
T = Sm.doit()
assert T == fibonacci(n)*fibonacci(n + 1)
@XFAIL
def test_R13():
n, k = symbols('n k', integer=True, positive=True)
Sm = Sum(sin(k*x), (k, 1, n))
T = Sm.doit() # Sum is not calculated
assert T.simplify() == cot(x/2)/2 - cos(x*(2*n + 1)/2)/(2*sin(x/2))
@XFAIL
def test_R14():
n, k = symbols('n k', integer=True, positive=True)
Sm = Sum(sin((2*k - 1)*x), (k, 1, n))
T = Sm.doit() # Sum is not calculated
assert T.simplify() == sin(n*x)**2/sin(x)
@XFAIL
def test_R15():
n, k = symbols('n k', integer=True, positive=True)
Sm = Sum(binomial(n - k, k), (k, 0, floor(n/2)))
T = Sm.doit() # Sum is not calculated
assert T.simplify() == fibonacci(n + 1)
def test_R16():
k = symbols('k', integer=True, positive=True)
Sm = Sum(1/k**2 + 1/k**3, (k, 1, oo))
assert Sm.doit() == zeta(3) + pi**2/6
def test_R17():
k = symbols('k', integer=True, positive=True)
assert abs(float(Sum(1/k**2 + 1/k**3, (k, 1, oo)))
- 2.8469909700078206) < 1e-15
def test_R18():
k = symbols('k', integer=True, positive=True)
Sm = Sum(1/(2**k*k**2), (k, 1, oo))
T = Sm.doit()
assert T.simplify() == -log(2)**2/2 + pi**2/12
@slow
@XFAIL
def test_R19():
k = symbols('k', integer=True, positive=True)
Sm = Sum(1/((3*k + 1)*(3*k + 2)*(3*k + 3)), (k, 0, oo))
T = Sm.doit()
# assert fails, T not simplified
assert T.simplify() == -log(3)/4 + sqrt(3)*pi/12
@XFAIL
def test_R20():
n, k = symbols('n k', integer=True, positive=True)
Sm = Sum(binomial(n, 4*k), (k, 0, oo))
T = Sm.doit()
# assert fails, T not simplified
assert T.simplify() == 2**(n/2)*cos(pi*n/4)/2 + 2**(n - 1)/2
@XFAIL
def test_R21():
k = symbols('k', integer=True, positive=True)
Sm = Sum(1/(sqrt(k*(k + 1)) * (sqrt(k) + sqrt(k + 1))), (k, 1, oo))
T = Sm.doit() # Sum not calculated
assert T.simplify() == 1
# test_R22 answer not available in Wester samples
# Sum(Sum(binomial(n, k)*binomial(n - k, n - 2*k)*x**n*y**(n - 2*k),
# (k, 0, floor(n/2))), (n, 0, oo)) with abs(x*y)<1?
@XFAIL
def test_R23():
n, k = symbols('n k', integer=True, positive=True)
Sm = Sum(Sum((factorial(n)/(factorial(k)**2*factorial(n - 2*k)))*
(x/y)**k*(x*y)**(n - k), (n, 2*k, oo)), (k, 0, oo))
# Missing how to express constraint abs(x*y)<1?
T = Sm.doit() # Sum not calculated
assert T == -1/sqrt(x**2*y**2 - 4*x**2 - 2*x*y + 1)
def test_R24():
m, k = symbols('m k', integer=True, positive=True)
Sm = Sum(Product(k/(2*k - 1), (k, 1, m)), (m, 2, oo))
assert Sm.doit() == pi/2
def test_S1():
k = symbols('k', integer=True, positive=True)
Pr = Product(gamma(k/3), (k, 1, 8))
assert Pr.doit().simplify() == 640*sqrt(3)*pi**3/6561
def test_S2():
n, k = symbols('n k', integer=True, positive=True)
assert Product(k, (k, 1, n)).doit() == factorial(n)
def test_S3():
n, k = symbols('n k', integer=True, positive=True)
assert Product(x**k, (k, 1, n)).doit().simplify() == x**(n*(n + 1)/2)
def test_S4():
n, k = symbols('n k', integer=True, positive=True)
assert Product(1 + 1/k, (k, 1, n -1)).doit().simplify() == n
def test_S5():
n, k = symbols('n k', integer=True, positive=True)
assert (Product((2*k - 1)/(2*k), (k, 1, n)).doit().gammasimp() ==
gamma(n + Rational(1, 2))/(sqrt(pi)*gamma(n + 1)))
@SKIP("https://github.com/sympy/sympy/issues/7133")
def test_S6():
n, k = symbols('n k', integer=True, positive=True)
# Product raises Infinite recursion error.
# https://github.com/sympy/sympy/issues/7133
assert (Product(x**2 -2*x*cos(k*pi/n) + 1, (k, 1, n - 1)).doit().simplify()
== (x**(2*n) - 1)/(x**2 - 1))
@XFAIL
def test_S7():
k = symbols('k', integer=True, positive=True)
Pr = Product((k**3 - 1)/(k**3 + 1), (k, 2, oo))
T = Pr.doit()
assert T.simplify() == Rational(2, 3) # T simplifies incorrectly to 0
@XFAIL
def test_S8():
k = symbols('k', integer=True, positive=True)
Pr = Product(1 - 1/(2*k)**2, (k, 1, oo))
T = Pr.doit()
# T = nan https://github.com/sympy/sympy/issues/7136
assert T.simplify() == 2/pi
@SKIP("https://github.com/sympy/sympy/issues/7133")
def test_S9():
k = symbols('k', integer=True, positive=True)
Pr = Product(1 + (-1)**(k + 1)/(2*k - 1), (k, 1, oo))
# Product.doit() raises Infinite recursion error.
# https://github.com/sympy/sympy/issues/7133
T = Pr.doit()
assert T.simplify() == sqrt(2)
@SKIP("https://github.com/sympy/sympy/issues/7137")
def test_S10():
k = symbols('k', integer=True, positive=True)
Pr = Product((k*(k + 1) + 1 + I)/(k*(k + 1) + 1 - I), (k, 0, oo))
T = Pr.doit()
# raises OverflowError
# https://github.com/sympy/sympy/issues/7137
assert T.simplify() == -1
def test_T1():
assert limit((1 + 1/n)**n, n, oo) == E
assert limit((1 - cos(x))/x**2, x, 0) == Rational(1, 2)
def test_T2():
assert limit((3**x + 5**x)**(1/x), x, oo) == 5
def test_T3():
assert limit(log(x)/(log(x) + sin(x)), x, oo) == 1
def test_T4():
assert limit((exp(x*exp(-x)/(exp(-x) + exp(-2*x**2/(x + 1))))
- exp(x))/x, x, oo) == -exp(2)
@slow
def test_T5():
assert limit(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)
def test_T6():
assert limit(1/n * factorial(n)**(1/n), n, oo) == exp(-1)
def test_T7():
limit(1/n * gamma(n + 1)**(1/n), n, oo)
def test_T8():
a, z = symbols('a z', real=True, positive=True)
assert limit(gamma(z + a)/gamma(z)*exp(-a*log(z)), z, oo) == 1
@XFAIL
def test_T9():
z, k = symbols('z k', real=True, positive=True)
# raises NotImplementedError:
# Don't know how to calculate the mrv of '(1, k)'
assert limit(hyper((1, k), (1,), z/k), k, oo) == exp(z)
@XFAIL
def test_T10():
# raises PoleError should return euler-mascheroni constant
limit(zeta(x) - 1/(x - 1), x, 1)
@XFAIL
def test_T11():
n, k = symbols('n k', integer=True, positive=True)
# raises NotImplementedError
assert limit(n**x/(x*product((1 + x/k), (k, 1, n))), n, oo) == gamma(x)
@XFAIL
def test_T12():
x, t = symbols('x t', real=True)
# raises PoleError: Don't know how to calculate the
# limit(sqrt(pi)*x*erf(x)/(2*(1 - exp(-x**2))), x, 0, dir=+)
assert limit(x * integrate(exp(-t**2), (t, 0, x))/(1 - exp(-x**2)),
x, 0) == 1
def test_T13():
x = symbols('x', real=True)
assert [limit(x/abs(x), x, 0, dir='-'),
limit(x/abs(x), x, 0, dir='+')] == [-1, 1]
def test_T14():
x = symbols('x', real=True)
assert limit(atan(-log(x)), x, 0, dir='+') == pi/2
def test_U1():
x = symbols('x', real=True)
assert diff(abs(x), x) == sign(x)
def test_U2():
f = Lambda(x, Piecewise((-x, x < 0), (x, x >= 0)))
assert diff(f(x), x) == Piecewise((-1, x < 0), (1, x >= 0))
def test_U3():
f = Lambda(x, Piecewise((x**2 - 1, x == 1), (x**3, x != 1)))
f1 = Lambda(x, diff(f(x), x))
assert f1(x) == 3*x**2
assert f1(1) == 3
@XFAIL
def test_U4():
n = symbols('n', integer=True, positive=True)
x = symbols('x', real=True)
diff(x**n, x, n)
assert diff(x**n, x, n).rewrite(factorial) == factorial(n)
def test_U5():
# issue 6681
t = symbols('t')
ans = (
Derivative(f(g(t)), g(t))*Derivative(g(t), (t, 2)) +
Derivative(f(g(t)), (g(t), 2))*Derivative(g(t), t)**2)
assert f(g(t)).diff(t, 2) == ans
assert ans.doit() == ans
def test_U6():
h = Function('h')
T = integrate(f(y), (y, h(x), g(x)))
assert T.diff(x) == (
f(g(x))*Derivative(g(x), x) - f(h(x))*Derivative(h(x), x))
@XFAIL
def test_U7():
p, t = symbols('p t', real=True)
# Exact differential => d(V(P, T)) => dV/dP DP + dV/dT DT
# raises ValueError: Since there is more than one variable in the
# expression, the variable(s) of differentiation must be supplied to
# differentiate f(p,t)
diff(f(p, t))
def test_U8():
x, y = symbols('x y', real=True)
eq = cos(x*y) + x
# If SymPy had implicit_diff() function this hack could be avoided
# TODO: Replace solve with solveset, current test fails for solveset
assert idiff(y - eq, y, x) == (-y*sin(x*y) + 1)/(x*sin(x*y) + 1)
def test_U9():
# Wester sample case for Maple:
# O29 := diff(f(x, y), x) + diff(f(x, y), y);
# /d \ /d \
# |-- f(x, y)| + |-- f(x, y)|
# \dx / \dy /
#
# O30 := factor(subs(f(x, y) = g(x^2 + y^2), %));
# 2 2
# 2 D(g)(x + y ) (x + y)
x, y = symbols('x y', real=True)
su = diff(f(x, y), x) + diff(f(x, y), y)
s2 = su.subs(f(x, y), g(x**2 + y**2))
s3 = s2.doit().factor()
# Subs not performed, s3 = 2*(x + y)*Subs(Derivative(
# g(_xi_1), _xi_1), _xi_1, x**2 + y**2)
# Derivative(g(x*2 + y**2), x**2 + y**2) is not valid in SymPy,
# and probably will remain that way. You can take derivatives with respect
# to other expressions only if they are atomic, like a symbol or a
# function.
# D operator should be added to SymPy
# See https://github.com/sympy/sympy/issues/4719.
assert s3 == (x + y)*Subs(Derivative(g(x), x), x, x**2 + y**2)*2
def test_U10():
# see issue 2519:
assert residue((z**3 + 5)/((z**4 - 1)*(z + 1)), z, -1) == Rational(-9, 4)
@XFAIL
def test_U11():
assert (2*dx + dz) ^ (3*dx + dy + dz) ^ (dx + dy + 4*dz) == 8*dx ^ dy ^dz
@XFAIL
def test_U12():
# Wester sample case:
# (c41) /* d(3 x^5 dy /\ dz + 5 x y^2 dz /\ dx + 8 z dx /\ dy)
# => (15 x^4 + 10 x y + 8) dx /\ dy /\ dz */
# factor(ext_diff(3*x^5 * dy ~ dz + 5*x*y^2 * dz ~ dx + 8*z * dx ~ dy));
# 4
# (d41) (10 x y + 15 x + 8) dx dy dz
raise NotImplementedError(
"External diff of differential form not supported")
@XFAIL
def test_U13():
#assert minimize(x**4 - x + 1, x)== -3*2**Rational(1,3)/8 + 1
raise NotImplementedError("minimize() not supported")
@XFAIL
def test_U14():
#f = 1/(x**2 + y**2 + 1)
#assert [minimize(f), maximize(f)] == [0,1]
raise NotImplementedError("minimize(), maximize() not supported")
@XFAIL
def test_U15():
raise NotImplementedError("minimize() not supported and also solve does \
not support multivariate inequalities")
@XFAIL
def test_U16():
raise NotImplementedError("minimize() not supported in SymPy and also \
solve does not support multivariate inequalities")
@XFAIL
def test_U17():
raise NotImplementedError("Linear programming, symbolic simplex not \
supported in SymPy")
def test_V1():
x = symbols('x', real=True)
assert integrate(abs(x), x) == Piecewise((-x**2/2, x <= 0), (x**2/2, True))
def test_V2():
assert integrate(Piecewise((-x, x < 0), (x, x >= 0)), x
) == Piecewise((-x**2/2, x < 0), (x**2/2, True))
def test_V3():
assert integrate(1/(x**3 + 2),x).diff().simplify() == 1/(x**3 + 2)
def test_V4():
assert integrate(2**x/sqrt(1 + 4**x), x) == asinh(2**x)/log(2)
@XFAIL
@slow
def test_V5():
# Takes extremely long time
# https://github.com/sympy/sympy/issues/7149
assert (integrate((3*x - 5)**2/(2*x - 1)**(Rational(7, 2)), x) ==
(-41 + 80*x - 45*x**2)/(5*(2*x - 1)**Rational(5, 2)))
@XFAIL
def test_V6():
# returns RootSum(40*_z**2 - 1, Lambda(_i, _i*log(-4*_i + exp(-m*x))))/m
assert (integrate(1/(2*exp(m*x) - 5*exp(-m*x)), x) == sqrt(10)*(
log(2*exp(m*x) - sqrt(10)) - log(2*exp(m*x) + sqrt(10)))/(20*m))
def test_V7():
r1 = integrate(sinh(x)**4/cosh(x)**2)
assert r1.simplify() == -3*x/2 + sinh(x)**3/(2*cosh(x)) + 3*tanh(x)/2
@XFAIL
def test_V8_V9():
#Macsyma test case:
#(c27) /* This example involves several symbolic parameters
# => 1/sqrt(b^2 - a^2) log([sqrt(b^2 - a^2) tan(x/2) + a + b]/
# [sqrt(b^2 - a^2) tan(x/2) - a - b]) (a^2 < b^2)
# [Gradshteyn and Ryzhik 2.553(3)] */
#assume(b^2 > a^2)$
#(c28) integrate(1/(a + b*cos(x)), x);
#(c29) trigsimp(ratsimp(diff(%, x)));
# 1
#(d29) ------------
# b cos(x) + a
raise NotImplementedError(
"Integrate with assumption not supported")
def test_V10():
assert integrate(1/(3 + 3*cos(x) + 4*sin(x)), x) == log(tan(x/2) + Rational(3, 4))/4
def test_V11():
r1 = integrate(1/(4 + 3*cos(x) + 4*sin(x)), x)
r2 = factor(r1)
assert (logcombine(r2, force=True) ==
log(((tan(x/2) + 1)/(tan(x/2) + 7))**Rational(1, 3)))
@XFAIL
def test_V12():
r1 = integrate(1/(5 + 3*cos(x) + 4*sin(x)), x)
# Correct result in python2.7.4 wrong result in python3.3.1
# https://github.com/sympy/sympy/issues/7157
assert r1 == -1/(tan(x/2) + 2)
@slow
@XFAIL
def test_V13():
r1 = integrate(1/(6 + 3*cos(x) + 4*sin(x)), x)
# expression not simplified, returns: -sqrt(11)*I*log(tan(x/2) + 4/3
# - sqrt(11)*I/3)/11 + sqrt(11)*I*log(tan(x/2) + 4/3 + sqrt(11)*I/3)/11
assert r1.simplify() == 2*sqrt(11)*atan(sqrt(11)*(3*tan(x/2) + 4)/11)/11
@slow
@XFAIL
def test_V14():
r1 = integrate(log(abs(x**2 - y**2)), x)
# Piecewise result does not simplify to the desired result.
assert (r1.simplify() == x*log(abs(x**2 - y**2))
+ y*log(x + y) - y*log(x - y) - 2*x)
def test_V15():
r1 = integrate(x*acot(x/y), x)
assert simplify(r1 - (x*y + (x**2 + y**2)*acot(x/y))/2) == 0
@XFAIL
def test_V16():
# test case in Mathematica syntax:
# In[53]:= Integrate[Cos[5*x]*CosIntegral[2*x], x]
# CosIntegral[2 x] Sin[5 x] -SinIntegral[3 x] - SinIntegral[7 x]
# Out[53]= ------------------------- + ------------------------------------
# 5 10
# cosine Integral function not supported
# http://reference.wolfram.com/mathematica/ref/CosIntegral.html
raise NotImplementedError("cosine integral function not supported")
@slow
@XFAIL
def test_V17():
r1 = integrate((diff(f(x), x)*g(x)
- f(x)*diff(g(x), x))/(f(x)**2 - g(x)**2), x)
# integral not calculated
assert simplify(r1 - (f(x) - g(x))/(f(x) + g(x))/2) == 0
@XFAIL
def test_W1():
# The function has a pole at y.
# The integral has a Cauchy principal value of zero but SymPy returns -I*pi
# https://github.com/sympy/sympy/issues/7159
assert integrate(1/(x - y), (x, y - 1, y + 1)) == 0
@XFAIL
def test_W2():
# The function has a pole at y.
# The integral is divergent but SymPy returns -2
# https://github.com/sympy/sympy/issues/7160
# Test case in Macsyma:
# (c6) errcatch(integrate(1/(x - a)^2, x, a - 1, a + 1));
# Integral is divergent
assert integrate(1/(x - y)**2, (x, y - 1, y + 1)) == zoo
@XFAIL
def test_W3():
# integral is not calculated
# https://github.com/sympy/sympy/issues/7161
assert integrate(sqrt(x + 1/x - 2), (x, 0, 1)) == S(4)/3
@XFAIL
def test_W4():
# integral is not calculated
assert integrate(sqrt(x + 1/x - 2), (x, 1, 2)) == -2*sqrt(2)/3 + S(4)/3
@XFAIL
def test_W5():
# integral is not calculated
assert integrate(sqrt(x + 1/x - 2), (x, 0, 2)) == -2*sqrt(2)/3 + S(8)/3
@XFAIL
@slow
def test_W6():
# integral is not calculated
assert integrate(sqrt(2 - 2*cos(2*x))/2, (x, -3*pi/4, -pi/4)) == sqrt(2)
def test_W7():
a = symbols('a', real=True, positive=True)
r1 = integrate(cos(x)/(x**2 + a**2), (x, -oo, oo))
assert r1.simplify() == pi*exp(-a)/a
@XFAIL
def test_W8():
# Test case in Mathematica:
# In[19]:= Integrate[t^(a - 1)/(1 + t), {t, 0, Infinity},
# Assumptions -> 0 < a < 1]
# Out[19]= Pi Csc[a Pi]
raise NotImplementedError(
"Integrate with assumption 0 < a < 1 not supported")
@XFAIL
def test_W9():
# Integrand with a residue at infinity => -2 pi [sin(pi/5) + sin(2pi/5)]
# (principal value) [Levinson and Redheffer, p. 234] *)
r1 = integrate(5*x**3/(1 + x + x**2 + x**3 + x**4), (x, -oo, oo))
r2 = r1.doit()
assert r2 == -2*pi*(sqrt(-sqrt(5)/8 + 5/8) + sqrt(sqrt(5)/8 + 5/8))
@XFAIL
def test_W10():
# integrate(1/[1 + x + x^2 + ... + x^(2 n)], x = -infinity..infinity) =
# 2 pi/(2 n + 1) [1 + cos(pi/[2 n + 1])] csc(2 pi/[2 n + 1])
# [Levinson and Redheffer, p. 255] => 2 pi/5 [1 + cos(pi/5)] csc(2 pi/5) */
r1 = integrate(x/(1 + x + x**2 + x**4), (x, -oo, oo))
r2 = r1.doit()
assert r2 == 2*pi*(sqrt(5)/4 + 5/4)*csc(2*pi/5)/5
@XFAIL
def test_W11():
# integral not calculated
assert (integrate(sqrt(1 - x**2)/(1 + x**2), (x, -1, 1)) ==
pi*(-1 + sqrt(2)))
def test_W12():
p = symbols('p', real=True, positive=True)
q = symbols('q', real=True)
r1 = integrate(x*exp(-p*x**2 + 2*q*x), (x, -oo, oo))
assert r1.simplify() == sqrt(pi)*q*exp(q**2/p)/p**Rational(3, 2)
@XFAIL
def test_W13():
# Integral not calculated. Expected result is 2*(Euler_mascheroni_constant)
r1 = integrate(1/log(x) + 1/(1 - x) - log(log(1/x)), (x, 0, 1))
assert r1 == 2*EulerGamma
def test_W14():
assert integrate(sin(x)/x*exp(2*I*x), (x, -oo, oo)) == 0
@XFAIL
def test_W15():
# integral not calculated
assert integrate(log(gamma(x))*cos(6*pi*x), (x, 0, 1)) == S(1)/12
def test_W16():
assert integrate((1 + x)**3*legendre_poly(1, x)*legendre_poly(2, x),
(x, -1, 1)) == S(36)/35
def test_W17():
a, b = symbols('a b', real=True, positive=True)
assert integrate(exp(-a*x)*besselj(0, b*x),
(x, 0, oo)) == 1/(b*sqrt(a**2/b**2 + 1))
def test_W18():
assert integrate((besselj(1, x)/x)**2, (x, 0, oo)) == 4/(3*pi)
@XFAIL
def test_W19():
# integrate(cos_int(x)*bessel_j[0](2*sqrt(7*x)), x, 0, inf);
# Expected result is cos 7 - 1)/7 [Gradshteyn and Ryzhik 6.782(3)]
raise NotImplementedError("cosine integral function not supported")
@XFAIL
def test_W20():
# integral not calculated
assert (integrate(x**2*polylog(3, 1/(x + 1)), (x, 0, 1)) ==
-pi**2/36 - S(17)/108 + zeta(3)/4 +
(-pi**2/2 - 4*log(2) + log(2)**2 + 35/3)*log(2)/9)
def test_W21():
assert abs(N(integrate(x**2*polylog(3, 1/(x + 1)), (x, 0, 1)))
- 0.210882859565594) < 1e-15
def test_W22():
t, u = symbols('t u', real=True)
s = Lambda(x, Piecewise((1, And(x >= 1, x <= 2)), (0, True)))
assert integrate(s(t)*cos(t), (t, 0, u)) == Piecewise(
(0, u < 0),
(-sin(Min(1, u)) + sin(Min(2, u)), True))
@XFAIL
@slow
def test_W23():
a, b = symbols('a b', real=True, positive=True)
r1 = integrate(integrate(x/(x**2 + y**2), (x, a, b)), (y, -oo, oo))
assert r1.simplify() == pi*(-a + b)
@SKIP("integrate raises RuntimeError: maximum recursion depth exceeded")
@slow
def test_W23b():
# like W23 but limits are reversed
a, b = symbols('a b', real=True, positive=True)
r2 = integrate(integrate(x/(x**2 + y**2), (y, -oo, oo)), (x, a, b))
assert r2 == pi*(-a + b)
@XFAIL
@slow
def test_W24():
if ON_TRAVIS:
skip("Too slow for travis.")
x, y = symbols('x y', real=True)
r1 = integrate(integrate(sqrt(x**2 + y**2), (x, 0, 1)), (y, 0, 1))
assert (r1 - (sqrt(2) + asinh(1))/3).simplify() == 0
@XFAIL
@slow
def test_W25():
if ON_TRAVIS:
skip("Too slow for travis.")
a, x, y = symbols('a x y', real=True)
i1 = integrate(
sin(a)*sin(y)/sqrt(1 - sin(a)**2*sin(x)**2*sin(y)**2),
(x, 0, pi/2))
i2 = integrate(i1, (y, 0, pi/2))
assert (i2 - pi*a/2).simplify() == 0
def test_W26():
x, y = symbols('x y', real=True)
assert integrate(integrate(abs(y - x**2), (y, 0, 2)),
(x, -1, 1)) == S(46)/15
def test_W27():
a, b, c = symbols('a b c')
assert integrate(integrate(integrate(1, (z, 0, c*(1 - x/a - y/b))),
(y, 0, b*(1 - x/a))),
(x, 0, a)) == a*b*c/6
def test_X1():
v, c = symbols('v c', real=True)
assert (series(1/sqrt(1 - (v/c)**2), v, x0=0, n=8) ==
5*v**6/(16*c**6) + 3*v**4/(8*c**4) + v**2/(2*c**2) + 1 + O(v**8))
def test_X2():
v, c = symbols('v c', real=True)
s1 = series(1/sqrt(1 - (v/c)**2), v, x0=0, n=8)
assert (1/s1**2).series(v, x0=0, n=8) == -v**2/c**2 + 1 + O(v**8)
def test_X3():
s1 = (sin(x).series()/cos(x).series()).series()
s2 = tan(x).series()
assert s2 == x + x**3/3 + 2*x**5/15 + O(x**6)
assert s1 == s2
def test_X4():
s1 = log(sin(x)/x).series()
assert s1 == -x**2/6 - x**4/180 + O(x**6)
assert log(series(sin(x)/x)).series() == s1
@XFAIL
def test_X5():
# test case in Mathematica syntax:
# In[21]:= (* => [a f'(a d) + g(b d) + integrate(h(c y), y = 0..d)]
# + [a^2 f''(a d) + b g'(b d) + h(c d)] (x - d) *)
# In[22]:= D[f[a*x], x] + g[b*x] + Integrate[h[c*y], {y, 0, x}]
# Out[22]= g[b x] + Integrate[h[c y], {y, 0, x}] + a f'[a x]
# In[23]:= Series[%, {x, d, 1}]
# Out[23]= (g[b d] + Integrate[h[c y], {y, 0, d}] + a f'[a d]) +
# 2 2
# (h[c d] + b g'[b d] + a f''[a d]) (-d + x) + O[-d + x]
h = Function('h')
a, b, c, d = symbols('a b c d', real=True)
# series() raises NotImplementedError:
# The _eval_nseries method should be added to <class
# 'sympy.core.function.Subs'> to give terms up to O(x**n) at x=0
series(diff(f(a*x), x) + g(b*x) + integrate(h(c*y), (y, 0, x)),
x, x0=d, n=2)
# assert missing, until exception is removed
def test_X6():
# Taylor series of nonscalar objects (noncommutative multiplication)
# expected result => (B A - A B) t^2/2 + O(t^3) [Stanly Steinberg]
a, b = symbols('a b', commutative=False, scalar=False)
assert (series(exp((a + b)*x) - exp(a*x) * exp(b*x), x, x0=0, n=3) ==
x**2*(-a*b/2 + b*a/2) + O(x**3))
def test_X7():
# => sum( Bernoulli[k]/k! x^(k - 2), k = 1..infinity )
# = 1/x^2 - 1/(2 x) + 1/12 - x^2/720 + x^4/30240 + O(x^6)
# [Levinson and Redheffer, p. 173]
assert (series(1/(x*(exp(x) - 1)), x, 0, 7) == x**(-2) - 1/(2*x) +
S(1)/12 - x**2/720 + x**4/30240 - x**6/1209600 + O(x**7))
def test_X8():
# Puiseux series (terms with fractional degree):
# => 1/sqrt(x - 3/2 pi) + (x - 3/2 pi)^(3/2) / 12 + O([x - 3/2 pi]^(7/2))
# see issue 7167:
x = symbols('x', real=True)
assert (series(sqrt(sec(x)), x, x0=pi*3/2, n=4) ==
1/sqrt(x - 3*pi/2) + (x - 3*pi/2)**(S(3)/2)/12 +
(x - 3*pi/2)**(S(7)/2)/160 + O((x - 3*pi/2)**4, (x, 3*pi/2)))
def test_X9():
assert (series(x**x, x, x0=0, 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_X10():
z, w = symbols('z w')
assert (series(log(sinh(z)) + log(cosh(z + w)), z, x0=0, n=2) ==
log(cosh(w)) + log(z) + z*sinh(w)/cosh(w) + O(z**2))
def test_X11():
z, w = symbols('z w')
assert (series(log(sinh(z) * cosh(z + w)), z, x0=0, n=2) ==
log(cosh(w)) + log(z) + z*sinh(w)/cosh(w) + O(z**2))
@XFAIL
def test_X12():
# Look at the generalized Taylor series around x = 1
# Result => (x - 1)^a/e^b [1 - (a + 2 b) (x - 1) / 2 + O((x - 1)^2)]
a, b, x = symbols('a b x', real=True)
# series returns O(log(x)**2)
# https://github.com/sympy/sympy/issues/7168
assert (series(log(x)**a*exp(-b*x), x, x0=1, n=2) ==
(x - 1)**a/exp(b)*(1 - (a + 2*b)*(x - 1)/2 + O((x - 1)**2)))
def test_X13():
assert series(sqrt(2*x**2 + 1), x, x0=oo, n=1) == sqrt(2)*x + O(1/x, (x, oo))
@XFAIL
def test_X14():
# Wallis' product => 1/sqrt(pi n) + ... [Knopp, p. 385]
assert series(1/2**(2*n)*binomial(2*n, n),
n, x==oo, n=1) == 1/(sqrt(pi)*sqrt(n)) + O(1/x, (x, oo))
@SKIP("https://github.com/sympy/sympy/issues/7164")
def test_X15():
# => 0!/x - 1!/x^2 + 2!/x^3 - 3!/x^4 + O(1/x^5) [Knopp, p. 544]
x, t = symbols('x t', real=True)
# raises RuntimeError: maximum recursion depth exceeded
# https://github.com/sympy/sympy/issues/7164
e1 = integrate(exp(-t)/t, (t, x, oo))
assert (series(e1, x, x0=oo, n=5) ==
6/x**4 + 2/x**3 - 1/x**2 + 1/x + O(x**(-5), (x, oo)))
def test_X16():
# Multivariate Taylor series expansion => 1 - (x^2 + 2 x y + y^2)/2 + O(x^4)
assert (series(cos(x + y), x + y, x0=0, n=4) == 1 - (x + y)**2/2 +
O(x**4 + x**3*y + x**2*y**2 + x*y**3 + y**4, x, y))
@XFAIL
def test_X17():
# Power series (compute the general formula)
# (c41) powerseries(log(sin(x)/x), x, 0);
# /aquarius/data2/opt/local/macsyma_422/library1/trgred.so being loaded.
# inf
# ==== i1 2 i1 2 i1
# \ (- 1) 2 bern(2 i1) x
# (d41) > ------------------------------
# / 2 i1 (2 i1)!
# ====
# i1 = 1
raise NotImplementedError("Formal power series not supported")
@XFAIL
def test_X18():
# Power series (compute the general formula). Maple FPS:
# > FormalPowerSeries(exp(-x)*sin(x), x = 0);
# infinity
# ----- (1/2 k) k
# \ 2 sin(3/4 k Pi) x
# ) -------------------------
# / k!
# -----
raise NotImplementedError("Formal power series not supported")
@XFAIL
def test_X19():
# (c45) /* Derive an explicit Taylor series solution of y as a function of
# x from the following implicit relation:
# y = x - 1 + (x - 1)^2/2 + 2/3 (x - 1)^3 + (x - 1)^4 +
# 17/10 (x - 1)^5 + ...
# */
# x = sin(y) + cos(y);
# Time= 0 msecs
# (d45) x = sin(y) + cos(y)
#
# (c46) taylor_revert(%, y, 7);
raise NotImplementedError("Solve using series not supported. \
Inverse Taylor series expansion also not supported")
@XFAIL
def test_X20():
# Pade (rational function) approximation => (2 - x)/(2 + x)
# > numapprox[pade](exp(-x), x = 0, [1, 1]);
# bytes used=9019816, alloc=3669344, time=13.12
# 1 - 1/2 x
# ---------
# 1 + 1/2 x
# mpmath support numeric Pade approximant but there is
# no symbolic implementation in SymPy
# https://en.wikipedia.org/wiki/Pad%C3%A9_approximant
raise NotImplementedError("Symbolic Pade approximant not supported")
def test_X21():
"""
Test whether `fourier_series` of x periodical on the [-p, p] interval equals
`- (2 p / pi) sum( (-1)^n / n sin(n pi x / p), n = 1..infinity )`.
"""
p = symbols('p', positive=True)
n = symbols('n', positive=True, integer=True)
s = fourier_series(x, (x, -p, p))
# All cosine coefficients are equal to 0
assert s.an.formula == 0
# Check for sine coefficients
assert s.bn.formula.subs(s.bn.variables[0], 0) == 0
assert s.bn.formula.subs(s.bn.variables[0], n) == \
-2*p/pi * (-1)**n / n * sin(n*pi*x/p)
@XFAIL
def test_X22():
# (c52) /* => p / 2
# - (2 p / pi^2) sum( [1 - (-1)^n] cos(n pi x / p) / n^2,
# n = 1..infinity ) */
# fourier_series(abs(x), x, p);
# p
# (e52) a = -
# 0 2
#
# %nn
# (2 (- 1) - 2) p
# (e53) a = ------------------
# %nn 2 2
# %pi %nn
#
# (e54) b = 0
# %nn
#
# Time= 5290 msecs
# inf %nn %pi %nn x
# ==== (2 (- 1) - 2) cos(---------)
# \ p
# p > -------------------------------
# / 2
# ==== %nn
# %nn = 1 p
# (d54) ----------------------------------------- + -
# 2 2
# %pi
raise NotImplementedError("Fourier series not supported")
def test_Y1():
t = symbols('t', real=True, positive=True)
w = symbols('w', real=True)
s = symbols('s')
F, _, _ = laplace_transform(cos((w - 1)*t), t, s)
assert F == s/(s**2 + (w - 1)**2)
def test_Y2():
t = symbols('t', real=True, positive=True)
w = symbols('w', real=True)
s = symbols('s')
f = inverse_laplace_transform(s/(s**2 + (w - 1)**2), s, t)
assert f == cos(t*w - t)
@slow
@XFAIL
def test_Y3():
t = symbols('t', real=True, positive=True)
w = symbols('w', real=True)
s = symbols('s')
F, _, _ = laplace_transform(sinh(w*t)*cosh(w*t), t, s)
assert F == w/(s**2 - 4*w**2)
def test_Y4():
t = symbols('t', real=True, positive=True)
s = symbols('s')
F, _, _ = laplace_transform(erf(3/sqrt(t)), t, s)
assert F == (1 - exp(-6*sqrt(s)))/s
@XFAIL
def test_Y5_Y6():
# Solve y'' + y = 4 [H(t - 1) - H(t - 2)], y(0) = 1, y'(0) = 0 where H is the
# Heaviside (unit step) function (the RHS describes a pulse of magnitude 4 and
# duration 1). See David A. Sanchez, Richard C. Allen, Jr. and Walter T.
# Kyner, _Differential Equations: An Introduction_, Addison-Wesley Publishing
# Company, 1983, p. 211. First, take the Laplace transform of the ODE
# => s^2 Y(s) - s + Y(s) = 4/s [e^(-s) - e^(-2 s)]
# where Y(s) is the Laplace transform of y(t)
t = symbols('t', real=True, positive=True)
s = symbols('s')
y = Function('y')
F, _, _ = laplace_transform(diff(y(t), t, 2)
+ y(t)
- 4*(Heaviside(t - 1)
- Heaviside(t - 2)), t, s)
# Laplace transform for diff() not calculated
# https://github.com/sympy/sympy/issues/7176
assert (F == s**2*LaplaceTransform(y(t), t, s) - s
+ LaplaceTransform(y(t), t, s) - 4*exp(-s)/s + 4*exp(-2*s)/s)
# TODO implement second part of test case
# Now, solve for Y(s) and then take the inverse Laplace transform
# => Y(s) = s/(s^2 + 1) + 4 [1/s - s/(s^2 + 1)] [e^(-s) - e^(-2 s)]
# => y(t) = cos t + 4 {[1 - cos(t - 1)] H(t - 1) - [1 - cos(t - 2)] H(t - 2)}
@XFAIL
def test_Y7():
# What is the Laplace transform of an infinite square wave?
# => 1/s + 2 sum( (-1)^n e^(- s n a)/s, n = 1..infinity )
# [Sanchez, Allen and Kyner, p. 213]
t = symbols('t', real=True, positive=True)
a = symbols('a', real=True)
s = symbols('s')
F, _, _ = laplace_transform(1 + 2*Sum((-1)**n*Heaviside(t - n*a),
(n, 1, oo)), t, s)
# returns 2*LaplaceTransform(Sum((-1)**n*Heaviside(-a*n + t),
# (n, 1, oo)), t, s) + 1/s
# https://github.com/sympy/sympy/issues/7177
assert F == 2*Sum((-1)**n*exp(-a*n*s)/s, (n, 1, oo)) + 1/s
@XFAIL
def test_Y8():
assert fourier_transform(1, x, z) == DiracDelta(z)
def test_Y9():
assert (fourier_transform(exp(-9*x**2), x, z) ==
sqrt(pi)*exp(-pi**2*z**2/9)/3)
def test_Y10():
assert (fourier_transform(abs(x)*exp(-3*abs(x)), x, z) ==
(-8*pi**2*z**2 + 18)/(16*pi**4*z**4 + 72*pi**2*z**2 + 81))
@SKIP("https://github.com/sympy/sympy/issues/7181")
@slow
def test_Y11():
# => pi cot(pi s) (0 < Re s < 1) [Gradshteyn and Ryzhik 17.43(5)]
x, s = symbols('x s')
# raises RuntimeError: maximum recursion depth exceeded
# https://github.com/sympy/sympy/issues/7181
F, _, _ = mellin_transform(1/(1 - x), x, s)
assert F == pi*cot(pi*s)
@XFAIL
def test_Y12():
# => 2^(s - 4) gamma(s/2)/gamma(4 - s/2) (0 < Re s < 1)
# [Gradshteyn and Ryzhik 17.43(16)]
x, s = symbols('x s')
# returns Wrong value -2**(s - 4)*gamma(s/2 - 3)/gamma(-s/2 + 1)
# https://github.com/sympy/sympy/issues/7182
F, _, _ = mellin_transform(besselj(3, x)/x**3, x, s)
assert F == -2**(s - 4)*gamma(s/2)/gamma(-s/2 + 4)
@XFAIL
def test_Y13():
# Z[H(t - m T)] => z/[z^m (z - 1)] (H is the Heaviside (unit step) function) z
raise NotImplementedError("z-transform not supported")
@XFAIL
def test_Y14():
# Z[H(t - m T)] => z/[z^m (z - 1)] (H is the Heaviside (unit step) function)
raise NotImplementedError("z-transform not supported")
def test_Z1():
r = Function('r')
assert (rsolve(r(n + 2) - 2*r(n + 1) + r(n) - 2, r(n),
{r(0): 1, r(1): m}).simplify() == n**2 + n*(m - 2) + 1)
def test_Z2():
r = Function('r')
assert (rsolve(r(n) - (5*r(n - 1) - 6*r(n - 2)), r(n), {r(0): 0, r(1): 1})
== -2**n + 3**n)
def test_Z3():
# => r(n) = Fibonacci[n + 1] [Cohen, p. 83]
r = Function('r')
# recurrence solution is correct, Wester expects it to be simplified to
# fibonacci(n+1), but that is quite hard
assert (rsolve(r(n) - (r(n - 1) + r(n - 2)), r(n),
{r(1): 1, r(2): 2}).simplify()
== 2**(-n)*((1 + sqrt(5))**n*(sqrt(5) + 5) +
(-sqrt(5) + 1)**n*(-sqrt(5) + 5))/10)
@XFAIL
def test_Z4():
# => [c^(n+1) [c^(n+1) - 2 c - 2] + (n+1) c^2 + 2 c - n] / [(c-1)^3 (c+1)]
# [Joan Z. Yu and Robert Israel in sci.math.symbolic]
r = Function('r')
c = symbols('c')
# raises ValueError: Polynomial or rational function expected,
# got '(c**2 - c**n)/(c - c**n)
s = rsolve(r(n) - ((1 + c - c**(n-1) - c**(n+1))/(1 - c**n)*r(n - 1)
- c*(1 - c**(n-2))/(1 - c**(n-1))*r(n - 2) + 1),
r(n), {r(1): 1, r(2): (2 + 2*c + c**2)/(1 + c)})
assert (s - (c*(n + 1)*(c*(n + 1) - 2*c - 2) +
(n + 1)*c**2 + 2*c - n)/((c-1)**3*(c+1)) == 0)
@XFAIL
def test_Z5():
# Second order ODE with initial conditions---solve directly
# transform: f(t) = sin(2 t)/8 - t cos(2 t)/4
C1, C2 = symbols('C1 C2')
# initial conditions not supported, this is a manual workaround
# https://github.com/sympy/sympy/issues/4720
eq = Derivative(f(x), x, 2) + 4*f(x) - sin(2*x)
sol = dsolve(eq, f(x))
f0 = Lambda(x, sol.rhs)
assert f0(x) == C2*sin(2*x) + (C1 - x/4)*cos(2*x)
f1 = Lambda(x, diff(f0(x), x))
# TODO: Replace solve with solveset, when it works for solveset
const_dict = solve((f0(0), f1(0)))
result = f0(x).subs(C1, const_dict[C1]).subs(C2, const_dict[C2])
assert result == -x*cos(2*x)/4 + sin(2*x)/8
# Result is OK, but ODE solving with initial conditions should be
# supported without all this manual work
raise NotImplementedError('ODE solving with initial conditions \
not supported')
@XFAIL
def test_Z6():
# Second order ODE with initial conditions---solve using Laplace
# transform: f(t) = sin(2 t)/8 - t cos(2 t)/4
t = symbols('t', real=True, positive=True)
s = symbols('s')
eq = Derivative(f(t), t, 2) + 4*f(t) - sin(2*t)
F, _, _ = laplace_transform(eq, t, s)
# Laplace transform for diff() not calculated
# https://github.com/sympy/sympy/issues/7176
assert (F == s**2*LaplaceTransform(f(t), t, s) +
4*LaplaceTransform(f(t), t, s) - 2/(s**2 + 4))
# rest of test case not implemented
|
0fccf6d9207def3f31bff57829d2286a9e13f0151b326cd6b2110d13b8262636
|
from sympy import (
Add, Abs, Chi, Ci, CosineTransform, Dict, Ei, Eq, FallingFactorial,
FiniteSet, Float, FourierTransform, Function, Indexed, IndexedBase, Integral,
Interval, InverseCosineTransform, InverseFourierTransform,
InverseLaplaceTransform, InverseMellinTransform, InverseSineTransform,
Lambda, LaplaceTransform, Limit, Matrix, Max, MellinTransform, Min, Mul,
Order, Piecewise, Poly, ring, field, ZZ, Pow, Product, Range, Rational,
RisingFactorial, rootof, RootSum, S, Shi, Si, SineTransform, Subs,
Sum, Symbol, ImageSet, Tuple, Union, Ynm, Znm, arg, asin, acsc, Mod,
assoc_laguerre, assoc_legendre, beta, binomial, catalan, ceiling, Complement,
chebyshevt, chebyshevu, conjugate, cot, coth, diff, dirichlet_eta, euler,
exp, expint, factorial, factorial2, floor, gamma, gegenbauer, hermite,
hyper, im, jacobi, laguerre, legendre, lerchphi, log,
meijerg, oo, polar_lift, polylog, re, root, sin, sqrt, symbols,
uppergamma, zeta, subfactorial, totient, elliptic_k, elliptic_f,
elliptic_e, elliptic_pi, cos, tan, Wild, true, false, Equivalent, Not,
Contains, divisor_sigma, SymmetricDifference, SeqPer, SeqFormula,
SeqAdd, SeqMul, fourier_series, pi, ConditionSet, ComplexRegion, fps,
AccumBounds, reduced_totient, primenu, primeomega, SingularityFunction,
UnevaluatedExpr, Quaternion)
from sympy.ntheory.factor_ import udivisor_sigma
from sympy.abc import mu, tau
from sympy.printing.latex import (latex, translate, greek_letters_set,
tex_greek_dictionary)
from sympy.tensor.array import (ImmutableDenseNDimArray, ImmutableSparseNDimArray,
MutableSparseNDimArray, MutableDenseNDimArray)
from sympy.tensor.array import tensorproduct
from sympy.utilities.pytest import XFAIL, raises
from sympy.functions import DiracDelta, Heaviside, KroneckerDelta, LeviCivita
from sympy.logic import Implies
from sympy.logic.boolalg import And, Or, Xor
from sympy.physics.quantum import Commutator, Operator
from sympy.physics.units import degree, radian, kg, meter, R
from sympy.core.trace import Tr
from sympy.core.compatibility import range
from sympy.combinatorics.permutations import Cycle, Permutation
from sympy import MatrixSymbol, ln
from sympy.vector import CoordSys3D, Cross, Curl, Dot, Divergence, Gradient
from sympy.sets.setexpr import SetExpr
import sympy as sym
class lowergamma(sym.lowergamma):
pass # testing notation inheritance by a subclass with same name
x, y, z, t, a, b, c = symbols('x y z t a b c')
k, m, n = symbols('k m n', integer=True)
def test_printmethod():
class R(Abs):
def _latex(self, printer):
return "foo(%s)" % printer._print(self.args[0])
assert latex(R(x)) == "foo(x)"
class R(Abs):
def _latex(self, printer):
return "foo"
assert latex(R(x)) == "foo"
def test_latex_basic():
assert latex(1 + x) == "x + 1"
assert latex(x**2) == "x^{2}"
assert latex(x**(1 + x)) == "x^{x + 1}"
assert latex(x**3 + x + 1 + x**2) == "x^{3} + x^{2} + x + 1"
assert latex(2*x*y) == "2 x y"
assert latex(2*x*y, mul_symbol='dot') == r"2 \cdot x \cdot y"
assert latex(3*x**2*y, mul_symbol='\\,') == r"3\,x^{2}\,y"
assert latex(1.5*3**x, mul_symbol='\\,') == r"1.5 \cdot 3^{x}"
assert latex(1/x) == r"\frac{1}{x}"
assert latex(1/x, fold_short_frac=True) == "1 / x"
assert latex(-S(3)/2) == r"- \frac{3}{2}"
assert latex(-S(3)/2, fold_short_frac=True) == r"- 3 / 2"
assert latex(1/x**2) == r"\frac{1}{x^{2}}"
assert latex(1/(x + y)/2) == r"\frac{1}{2 \left(x + y\right)}"
assert latex(x/2) == r"\frac{x}{2}"
assert latex(x/2, fold_short_frac=True) == "x / 2"
assert latex((x + y)/(2*x)) == r"\frac{x + y}{2 x}"
assert latex((x + y)/(2*x), fold_short_frac=True) == \
r"\left(x + y\right) / 2 x"
assert latex((x + y)/(2*x), long_frac_ratio=0) == \
r"\frac{1}{2 x} \left(x + y\right)"
assert latex((x + y)/x) == r"\frac{x + y}{x}"
assert latex((x + y)/x, long_frac_ratio=3) == r"\frac{x + y}{x}"
assert latex((2*sqrt(2)*x)/3) == r"\frac{2 \sqrt{2} x}{3}"
assert latex((2*sqrt(2)*x)/3, long_frac_ratio=2) == \
r"\frac{2 x}{3} \sqrt{2}"
assert latex(2*Integral(x, x)/3) == r"\frac{2 \int x\, dx}{3}"
assert latex(2*Integral(x, x)/3, fold_short_frac=True) == \
r"\left(2 \int x\, dx\right) / 3"
assert latex(sqrt(x)) == r"\sqrt{x}"
assert latex(x**Rational(1, 3)) == r"\sqrt[3]{x}"
assert latex(sqrt(x)**3) == r"x^{\frac{3}{2}}"
assert latex(sqrt(x), itex=True) == r"\sqrt{x}"
assert latex(x**Rational(1, 3), itex=True) == r"\root{3}{x}"
assert latex(sqrt(x)**3, itex=True) == r"x^{\frac{3}{2}}"
assert latex(x**Rational(3, 4)) == r"x^{\frac{3}{4}}"
assert latex(x**Rational(3, 4), fold_frac_powers=True) == "x^{3/4}"
assert latex((x + 1)**Rational(3, 4)) == \
r"\left(x + 1\right)^{\frac{3}{4}}"
assert latex((x + 1)**Rational(3, 4), fold_frac_powers=True) == \
r"\left(x + 1\right)^{3/4}"
assert latex(1.5e20*x) == r"1.5 \cdot 10^{20} x"
assert latex(1.5e20*x, mul_symbol='dot') == r"1.5 \cdot 10^{20} \cdot x"
assert latex(1.5e20*x, mul_symbol='times') == r"1.5 \times 10^{20} \times x"
assert latex(1/sin(x)) == r"\frac{1}{\sin{\left(x \right)}}"
assert latex(sin(x)**-1) == r"\frac{1}{\sin{\left(x \right)}}"
assert latex(sin(x)**Rational(3, 2)) == \
r"\sin^{\frac{3}{2}}{\left(x \right)}"
assert latex(sin(x)**Rational(3, 2), fold_frac_powers=True) == \
r"\sin^{3/2}{\left(x \right)}"
assert latex(~x) == r"\neg x"
assert latex(x & y) == r"x \wedge y"
assert latex(x & y & z) == r"x \wedge y \wedge z"
assert latex(x | y) == r"x \vee y"
assert latex(x | y | z) == r"x \vee y \vee z"
assert latex((x & y) | z) == r"z \vee \left(x \wedge y\right)"
assert latex(Implies(x, y)) == r"x \Rightarrow y"
assert latex(~(x >> ~y)) == r"x \not\Rightarrow \neg y"
assert latex(Implies(Or(x,y), z)) == r"\left(x \vee y\right) \Rightarrow z"
assert latex(Implies(z, Or(x,y))) == r"z \Rightarrow \left(x \vee y\right)"
assert latex(~x, symbol_names={x: "x_i"}) == r"\neg x_i"
assert latex(x & y, symbol_names={x: "x_i", y: "y_i"}) == \
r"x_i \wedge y_i"
assert latex(x & y & z, symbol_names={x: "x_i", y: "y_i", z: "z_i"}) == \
r"x_i \wedge y_i \wedge z_i"
assert latex(x | y, symbol_names={x: "x_i", y: "y_i"}) == r"x_i \vee y_i"
assert latex(x | y | z, symbol_names={x: "x_i", y: "y_i", z: "z_i"}) == \
r"x_i \vee y_i \vee z_i"
assert latex((x & y) | z, symbol_names={x: "x_i", y: "y_i", z: "z_i"}) == \
r"z_i \vee \left(x_i \wedge y_i\right)"
assert latex(Implies(x, y), symbol_names={x: "x_i", y: "y_i"}) == \
r"x_i \Rightarrow y_i"
p = Symbol('p', positive=True)
assert latex(exp(-p)*log(p)) == r"e^{- p} \log{\left(p \right)}"
def test_latex_builtins():
assert latex(True) == r"\mathrm{True}"
assert latex(False) == r"\mathrm{False}"
assert latex(None) == r"\mathrm{None}"
assert latex(true) == r"\mathrm{True}"
assert latex(false) == r'\mathrm{False}'
def test_latex_SingularityFunction():
assert latex(SingularityFunction(x, 4, 5)) == r"{\left\langle x - 4 \right\rangle}^{5}"
assert latex(SingularityFunction(x, -3, 4)) == r"{\left\langle x + 3 \right\rangle}^{4}"
assert latex(SingularityFunction(x, 0, 4)) == r"{\left\langle x \right\rangle}^{4}"
assert latex(SingularityFunction(x, a, n)) == r"{\left\langle - a + x \right\rangle}^{n}"
assert latex(SingularityFunction(x, 4, -2)) == r"{\left\langle x - 4 \right\rangle}^{-2}"
assert latex(SingularityFunction(x, 4, -1)) == r"{\left\langle x - 4 \right\rangle}^{-1}"
def test_latex_cycle():
assert latex(Cycle(1, 2, 4)) == r"\left( 1\; 2\; 4\right)"
assert latex(Cycle(1, 2)(4, 5, 6)) == r"\left( 1\; 2\right)\left( 4\; 5\; 6\right)"
assert latex(Cycle()) == r"\left( \right)"
def test_latex_permutation():
assert latex(Permutation(1, 2, 4)) == r"\left( 1\; 2\; 4\right)"
assert latex(Permutation(1, 2)(4, 5, 6)) == r"\left( 1\; 2\right)\left( 4\; 5\; 6\right)"
assert latex(Permutation()) == r"\left( \right)"
assert latex(Permutation(2, 4)*Permutation(5)) == r"\left( 2\; 4\right)\left( 5\right)"
assert latex(Permutation(5)) == r"\left( 5\right)"
def test_latex_Float():
assert latex(Float(1.0e100)) == r"1.0 \cdot 10^{100}"
assert latex(Float(1.0e-100)) == r"1.0 \cdot 10^{-100}"
assert latex(Float(1.0e-100), mul_symbol="times") == r"1.0 \times 10^{-100}"
assert latex(1.0*oo) == r"\infty"
assert latex(-1.0*oo) == r"- \infty"
def test_latex_vector_expressions():
A = CoordSys3D('A')
assert latex(Cross(A.i, A.j*A.x*3+A.k)) == r"\mathbf{\hat{i}_{A}} \times \left((3 \mathbf{{x}_{A}})\mathbf{\hat{j}_{A}} + \mathbf{\hat{k}_{A}}\right)"
assert latex(Cross(A.i, A.j)) == r"\mathbf{\hat{i}_{A}} \times \mathbf{\hat{j}_{A}}"
assert latex(x*Cross(A.i, A.j)) == r"x \left(\mathbf{\hat{i}_{A}} \times \mathbf{\hat{j}_{A}}\right)"
assert latex(Cross(x*A.i, A.j)) == r'- \mathbf{\hat{j}_{A}} \times \left((x)\mathbf{\hat{i}_{A}}\right)'
assert latex(Curl(3*A.x*A.j)) == r"\nabla\times \left((3 \mathbf{{x}_{A}})\mathbf{\hat{j}_{A}}\right)"
assert latex(Curl(3*A.x*A.j+A.i)) == r"\nabla\times \left(\mathbf{\hat{i}_{A}} + (3 \mathbf{{x}_{A}})\mathbf{\hat{j}_{A}}\right)"
assert latex(Curl(3*x*A.x*A.j)) == r"\nabla\times \left((3 \mathbf{{x}_{A}} x)\mathbf{\hat{j}_{A}}\right)"
assert latex(x*Curl(3*A.x*A.j)) == r"x \left(\nabla\times \left((3 \mathbf{{x}_{A}})\mathbf{\hat{j}_{A}}\right)\right)"
assert latex(Divergence(3*A.x*A.j+A.i)) == r"\nabla\cdot \left(\mathbf{\hat{i}_{A}} + (3 \mathbf{{x}_{A}})\mathbf{\hat{j}_{A}}\right)"
assert latex(Divergence(3*A.x*A.j)) == r"\nabla\cdot \left((3 \mathbf{{x}_{A}})\mathbf{\hat{j}_{A}}\right)"
assert latex(x*Divergence(3*A.x*A.j)) == r"x \left(\nabla\cdot \left((3 \mathbf{{x}_{A}})\mathbf{\hat{j}_{A}}\right)\right)"
assert latex(Dot(A.i, A.j*A.x*3+A.k)) == r"\mathbf{\hat{i}_{A}} \cdot \left((3 \mathbf{{x}_{A}})\mathbf{\hat{j}_{A}} + \mathbf{\hat{k}_{A}}\right)"
assert latex(Dot(A.i, A.j)) == r"\mathbf{\hat{i}_{A}} \cdot \mathbf{\hat{j}_{A}}"
assert latex(Dot(x*A.i, A.j)) == r"\mathbf{\hat{j}_{A}} \cdot \left((x)\mathbf{\hat{i}_{A}}\right)"
assert latex(x*Dot(A.i, A.j)) == r"x \left(\mathbf{\hat{i}_{A}} \cdot \mathbf{\hat{j}_{A}}\right)"
assert latex(Gradient(A.x)) == r"\nabla\cdot \mathbf{{x}_{A}}"
assert latex(Gradient(A.x + 3*A.y)) == r"\nabla\cdot \left(\mathbf{{x}_{A}} + 3 \mathbf{{y}_{A}}\right)"
assert latex(x*Gradient(A.x)) == r"x \left(\nabla\cdot \mathbf{{x}_{A}}\right)"
assert latex(Gradient(x*A.x)) == r"\nabla\cdot \left(\mathbf{{x}_{A}} x\right)"
def test_latex_symbols():
Gamma, lmbda, rho = symbols('Gamma, lambda, rho')
tau, Tau, TAU, taU = symbols('tau, Tau, TAU, taU')
assert latex(tau) == r"\tau"
assert latex(Tau) == "T"
assert latex(TAU) == r"\tau"
assert latex(taU) == r"\tau"
# Check that all capitalized greek letters are handled explicitly
capitalized_letters = set(l.capitalize() for l in greek_letters_set)
assert len(capitalized_letters - set(tex_greek_dictionary.keys())) == 0
assert latex(Gamma + lmbda) == r"\Gamma + \lambda"
assert latex(Gamma * lmbda) == r"\Gamma \lambda"
assert latex(Symbol('q1')) == r"q_{1}"
assert latex(Symbol('q21')) == r"q_{21}"
assert latex(Symbol('epsilon0')) == r"\epsilon_{0}"
assert latex(Symbol('omega1')) == r"\omega_{1}"
assert latex(Symbol('91')) == r"91"
assert latex(Symbol('alpha_new')) == r"\alpha_{new}"
assert latex(Symbol('C^orig')) == r"C^{orig}"
assert latex(Symbol('x^alpha')) == r"x^{\alpha}"
assert latex(Symbol('beta^alpha')) == r"\beta^{\alpha}"
assert latex(Symbol('e^Alpha')) == r"e^{A}"
assert latex(Symbol('omega_alpha^beta')) == r"\omega^{\beta}_{\alpha}"
assert latex(Symbol('omega') ** Symbol('beta')) == r"\omega^{\beta}"
@XFAIL
def test_latex_symbols_failing():
rho, mass, volume = symbols('rho, mass, volume')
assert latex(
volume * rho == mass) == r"\rho \mathrm{volume} = \mathrm{mass}"
assert latex(volume / mass * rho == 1) == r"\rho \mathrm{volume} {\mathrm{mass}}^{(-1)} = 1"
assert latex(mass**3 * volume**3) == r"{\mathrm{mass}}^{3} \cdot {\mathrm{volume}}^{3}"
def test_latex_functions():
assert latex(exp(x)) == "e^{x}"
assert latex(exp(1) + exp(2)) == "e + e^{2}"
f = Function('f')
assert latex(f(x)) == r'f{\left(x \right)}'
assert latex(f) == r'f'
g = Function('g')
assert latex(g(x, y)) == r'g{\left(x,y \right)}'
assert latex(g) == r'g'
h = Function('h')
assert latex(h(x, y, z)) == r'h{\left(x,y,z \right)}'
assert latex(h) == r'h'
Li = Function('Li')
assert latex(Li) == r'\operatorname{Li}'
assert latex(Li(x)) == r'\operatorname{Li}{\left(x \right)}'
mybeta = Function('beta')
# not to be confused with the beta function
assert latex(mybeta(x, y, z)) == r"\beta{\left(x,y,z \right)}"
assert latex(beta(x, y)) == r'\operatorname{B}\left(x, y\right)'
assert latex(mybeta(x)) == r"\beta{\left(x \right)}"
assert latex(mybeta) == r"\beta"
g = Function('gamma')
# not to be confused with the gamma function
assert latex(g(x, y, z)) == r"\gamma{\left(x,y,z \right)}"
assert latex(g(x)) == r"\gamma{\left(x \right)}"
assert latex(g) == r"\gamma"
a1 = Function('a_1')
assert latex(a1) == r"\operatorname{a_{1}}"
assert latex(a1(x)) == r"\operatorname{a_{1}}{\left(x \right)}"
# issue 5868
omega1 = Function('omega1')
assert latex(omega1) == r"\omega_{1}"
assert latex(omega1(x)) == r"\omega_{1}{\left(x \right)}"
assert latex(sin(x)) == r"\sin{\left(x \right)}"
assert latex(sin(x), fold_func_brackets=True) == r"\sin {x}"
assert latex(sin(2*x**2), fold_func_brackets=True) == \
r"\sin {2 x^{2}}"
assert latex(sin(x**2), fold_func_brackets=True) == \
r"\sin {x^{2}}"
assert latex(asin(x)**2) == r"\operatorname{asin}^{2}{\left(x \right)}"
assert latex(asin(x)**2, inv_trig_style="full") == \
r"\arcsin^{2}{\left(x \right)}"
assert latex(asin(x)**2, inv_trig_style="power") == \
r"\sin^{-1}{\left(x \right)}^{2}"
assert latex(asin(x**2), inv_trig_style="power",
fold_func_brackets=True) == \
r"\sin^{-1} {x^{2}}"
assert latex(acsc(x), inv_trig_style="full") == \
r"\operatorname{arccsc}{\left(x \right)}"
assert latex(factorial(k)) == r"k!"
assert latex(factorial(-k)) == r"\left(- k\right)!"
assert latex(subfactorial(k)) == r"!k"
assert latex(subfactorial(-k)) == r"!\left(- k\right)"
assert latex(factorial2(k)) == r"k!!"
assert latex(factorial2(-k)) == r"\left(- k\right)!!"
assert latex(binomial(2, k)) == r"{\binom{2}{k}}"
assert latex(FallingFactorial(3, k)) == r"{\left(3\right)}_{k}"
assert latex(RisingFactorial(3, k)) == r"{3}^{\left(k\right)}"
assert latex(floor(x)) == r"\left\lfloor{x}\right\rfloor"
assert latex(ceiling(x)) == r"\left\lceil{x}\right\rceil"
assert latex(Min(x, 2, x**3)) == r"\min\left(2, x, x^{3}\right)"
assert latex(Min(x, y)**2) == r"\min\left(x, y\right)^{2}"
assert latex(Max(x, 2, x**3)) == r"\max\left(2, x, x^{3}\right)"
assert latex(Max(x, y)**2) == r"\max\left(x, y\right)^{2}"
assert latex(Abs(x)) == r"\left|{x}\right|"
assert latex(re(x)) == r"\Re{\left(x\right)}"
assert latex(re(x + y)) == r"\Re{\left(x\right)} + \Re{\left(y\right)}"
assert latex(im(x)) == r"\Im{x}"
assert latex(conjugate(x)) == r"\overline{x}"
assert latex(gamma(x)) == r"\Gamma\left(x\right)"
w = Wild('w')
assert latex(gamma(w)) == r"\Gamma\left(w\right)"
assert latex(Order(x)) == r"O\left(x\right)"
assert latex(Order(x, x)) == r"O\left(x\right)"
assert latex(Order(x, (x, 0))) == r"O\left(x\right)"
assert latex(Order(x, (x, oo))) == r"O\left(x; x\rightarrow \infty\right)"
assert latex(Order(x - y, (x, y))) == r"O\left(x - y; x\rightarrow y\right)"
assert latex(Order(x, x, y)) == r"O\left(x; \left( x, \quad y\right)\rightarrow \left( 0, \quad 0\right)\right)"
assert latex(Order(x, x, y)) == r"O\left(x; \left( x, \quad y\right)\rightarrow \left( 0, \quad 0\right)\right)"
assert latex(Order(x, (x, oo), (y, oo))) == r"O\left(x; \left( x, \quad y\right)\rightarrow \left( \infty, \quad \infty\right)\right)"
assert latex(lowergamma(x, y)) == r'\gamma\left(x, y\right)'
assert latex(uppergamma(x, y)) == r'\Gamma\left(x, y\right)'
assert latex(cot(x)) == r'\cot{\left(x \right)}'
assert latex(coth(x)) == r'\coth{\left(x \right)}'
assert latex(re(x)) == r'\Re{\left(x\right)}'
assert latex(im(x)) == r'\Im{x}'
assert latex(root(x, y)) == r'x^{\frac{1}{y}}'
assert latex(arg(x)) == r'\arg{\left(x \right)}'
assert latex(zeta(x)) == r'\zeta\left(x\right)'
assert latex(zeta(x)) == r"\zeta\left(x\right)"
assert latex(zeta(x)**2) == r"\zeta^{2}\left(x\right)"
assert latex(zeta(x, y)) == r"\zeta\left(x, y\right)"
assert latex(zeta(x, y)**2) == r"\zeta^{2}\left(x, y\right)"
assert latex(dirichlet_eta(x)) == r"\eta\left(x\right)"
assert latex(dirichlet_eta(x)**2) == r"\eta^{2}\left(x\right)"
assert latex(polylog(x, y)) == r"\operatorname{Li}_{x}\left(y\right)"
assert latex(
polylog(x, y)**2) == r"\operatorname{Li}_{x}^{2}\left(y\right)"
assert latex(lerchphi(x, y, n)) == r"\Phi\left(x, y, n\right)"
assert latex(lerchphi(x, y, n)**2) == r"\Phi^{2}\left(x, y, n\right)"
assert latex(elliptic_k(z)) == r"K\left(z\right)"
assert latex(elliptic_k(z)**2) == r"K^{2}\left(z\right)"
assert latex(elliptic_f(x, y)) == r"F\left(x\middle| y\right)"
assert latex(elliptic_f(x, y)**2) == r"F^{2}\left(x\middle| y\right)"
assert latex(elliptic_e(x, y)) == r"E\left(x\middle| y\right)"
assert latex(elliptic_e(x, y)**2) == r"E^{2}\left(x\middle| y\right)"
assert latex(elliptic_e(z)) == r"E\left(z\right)"
assert latex(elliptic_e(z)**2) == r"E^{2}\left(z\right)"
assert latex(elliptic_pi(x, y, z)) == r"\Pi\left(x; y\middle| z\right)"
assert latex(elliptic_pi(x, y, z)**2) == \
r"\Pi^{2}\left(x; y\middle| z\right)"
assert latex(elliptic_pi(x, y)) == r"\Pi\left(x\middle| y\right)"
assert latex(elliptic_pi(x, y)**2) == r"\Pi^{2}\left(x\middle| y\right)"
assert latex(Ei(x)) == r'\operatorname{Ei}{\left(x \right)}'
assert latex(Ei(x)**2) == r'\operatorname{Ei}^{2}{\left(x \right)}'
assert latex(expint(x, y)**2) == r'\operatorname{E}_{x}^{2}\left(y\right)'
assert latex(Shi(x)**2) == r'\operatorname{Shi}^{2}{\left(x \right)}'
assert latex(Si(x)**2) == r'\operatorname{Si}^{2}{\left(x \right)}'
assert latex(Ci(x)**2) == r'\operatorname{Ci}^{2}{\left(x \right)}'
assert latex(Chi(x)**2) == r'\operatorname{Chi}^{2}\left(x\right)'
assert latex(Chi(x)) == r'\operatorname{Chi}\left(x\right)'
assert latex(
jacobi(n, a, b, x)) == r'P_{n}^{\left(a,b\right)}\left(x\right)'
assert latex(jacobi(n, a, b, x)**2) == r'\left(P_{n}^{\left(a,b\right)}\left(x\right)\right)^{2}'
assert latex(
gegenbauer(n, a, x)) == r'C_{n}^{\left(a\right)}\left(x\right)'
assert latex(gegenbauer(n, a, x)**2) == r'\left(C_{n}^{\left(a\right)}\left(x\right)\right)^{2}'
assert latex(chebyshevt(n, x)) == r'T_{n}\left(x\right)'
assert latex(
chebyshevt(n, x)**2) == r'\left(T_{n}\left(x\right)\right)^{2}'
assert latex(chebyshevu(n, x)) == r'U_{n}\left(x\right)'
assert latex(
chebyshevu(n, x)**2) == r'\left(U_{n}\left(x\right)\right)^{2}'
assert latex(legendre(n, x)) == r'P_{n}\left(x\right)'
assert latex(legendre(n, x)**2) == r'\left(P_{n}\left(x\right)\right)^{2}'
assert latex(
assoc_legendre(n, a, x)) == r'P_{n}^{\left(a\right)}\left(x\right)'
assert latex(assoc_legendre(n, a, x)**2) == r'\left(P_{n}^{\left(a\right)}\left(x\right)\right)^{2}'
assert latex(laguerre(n, x)) == r'L_{n}\left(x\right)'
assert latex(laguerre(n, x)**2) == r'\left(L_{n}\left(x\right)\right)^{2}'
assert latex(
assoc_laguerre(n, a, x)) == r'L_{n}^{\left(a\right)}\left(x\right)'
assert latex(assoc_laguerre(n, a, x)**2) == r'\left(L_{n}^{\left(a\right)}\left(x\right)\right)^{2}'
assert latex(hermite(n, x)) == r'H_{n}\left(x\right)'
assert latex(hermite(n, x)**2) == r'\left(H_{n}\left(x\right)\right)^{2}'
theta = Symbol("theta", real=True)
phi = Symbol("phi", real=True)
assert latex(Ynm(n,m,theta,phi)) == r'Y_{n}^{m}\left(\theta,\phi\right)'
assert latex(Ynm(n, m, theta, phi)**3) == r'\left(Y_{n}^{m}\left(\theta,\phi\right)\right)^{3}'
assert latex(Znm(n,m,theta,phi)) == r'Z_{n}^{m}\left(\theta,\phi\right)'
assert latex(Znm(n, m, theta, phi)**3) == r'\left(Z_{n}^{m}\left(\theta,\phi\right)\right)^{3}'
# Test latex printing of function names with "_"
assert latex(
polar_lift(0)) == r"\operatorname{polar\_lift}{\left(0 \right)}"
assert latex(polar_lift(
0)**3) == r"\operatorname{polar\_lift}^{3}{\left(0 \right)}"
assert latex(totient(n)) == r'\phi\left(n\right)'
assert latex(totient(n) ** 2) == r'\left(\phi\left(n\right)\right)^{2}'
assert latex(reduced_totient(n)) == r'\lambda\left(n\right)'
assert latex(reduced_totient(n) ** 2) == r'\left(\lambda\left(n\right)\right)^{2}'
assert latex(divisor_sigma(x)) == r"\sigma\left(x\right)"
assert latex(divisor_sigma(x)**2) == r"\sigma^{2}\left(x\right)"
assert latex(divisor_sigma(x, y)) == r"\sigma_y\left(x\right)"
assert latex(divisor_sigma(x, y)**2) == r"\sigma^{2}_y\left(x\right)"
assert latex(udivisor_sigma(x)) == r"\sigma^*\left(x\right)"
assert latex(udivisor_sigma(x)**2) == r"\sigma^*^{2}\left(x\right)"
assert latex(udivisor_sigma(x, y)) == r"\sigma^*_y\left(x\right)"
assert latex(udivisor_sigma(x, y)**2) == r"\sigma^*^{2}_y\left(x\right)"
assert latex(primenu(n)) == r'\nu\left(n\right)'
assert latex(primenu(n) ** 2) == r'\left(\nu\left(n\right)\right)^{2}'
assert latex(primeomega(n)) == r'\Omega\left(n\right)'
assert latex(primeomega(n) ** 2) == r'\left(\Omega\left(n\right)\right)^{2}'
assert latex(Mod(x, 7)) == r'x\bmod{7}'
assert latex(Mod(x + 1, 7)) == r'\left(x + 1\right)\bmod{7}'
assert latex(Mod(2 * x, 7)) == r'2 x\bmod{7}'
assert latex(Mod(x, 7) + 1) == r'\left(x\bmod{7}\right) + 1'
assert latex(2 * Mod(x, 7)) == r'2 \left(x\bmod{7}\right)'
# some unknown function name should get rendered with \operatorname
fjlkd = Function('fjlkd')
assert latex(fjlkd(x)) == r'\operatorname{fjlkd}{\left(x \right)}'
# even when it is referred to without an argument
assert latex(fjlkd) == r'\operatorname{fjlkd}'
# test that notation passes to subclasses of the same name only
def test_function_subclass_different_name():
class mygamma(gamma):
pass
assert latex(mygamma) == r"\operatorname{mygamma}"
assert latex(mygamma(x)) == r"\operatorname{mygamma}{\left(x \right)}"
def test_hyper_printing():
from sympy import pi
from sympy.abc import x, z
assert latex(meijerg(Tuple(pi, pi, x), Tuple(1),
(0, 1), Tuple(1, 2, 3/pi), z)) == \
r'{G_{4, 5}^{2, 3}\left(\begin{matrix} \pi, \pi, x & 1 \\0, 1 & 1, 2, \frac{3}{\pi} \end{matrix} \middle| {z} \right)}'
assert latex(meijerg(Tuple(), Tuple(1), (0,), Tuple(), z)) == \
r'{G_{1, 1}^{1, 0}\left(\begin{matrix} & 1 \\0 & \end{matrix} \middle| {z} \right)}'
assert latex(hyper((x, 2), (3,), z)) == \
r'{{}_{2}F_{1}\left(\begin{matrix} x, 2 ' \
r'\\ 3 \end{matrix}\middle| {z} \right)}'
assert latex(hyper(Tuple(), Tuple(1), z)) == \
r'{{}_{0}F_{1}\left(\begin{matrix} ' \
r'\\ 1 \end{matrix}\middle| {z} \right)}'
def test_latex_bessel():
from sympy.functions.special.bessel import (besselj, bessely, besseli,
besselk, hankel1, hankel2, jn, yn, hn1, hn2)
from sympy.abc import z
assert latex(besselj(n, z**2)**k) == r'J^{k}_{n}\left(z^{2}\right)'
assert latex(bessely(n, z)) == r'Y_{n}\left(z\right)'
assert latex(besseli(n, z)) == r'I_{n}\left(z\right)'
assert latex(besselk(n, z)) == r'K_{n}\left(z\right)'
assert latex(hankel1(n, z**2)**2) == \
r'\left(H^{(1)}_{n}\left(z^{2}\right)\right)^{2}'
assert latex(hankel2(n, z)) == r'H^{(2)}_{n}\left(z\right)'
assert latex(jn(n, z)) == r'j_{n}\left(z\right)'
assert latex(yn(n, z)) == r'y_{n}\left(z\right)'
assert latex(hn1(n, z)) == r'h^{(1)}_{n}\left(z\right)'
assert latex(hn2(n, z)) == r'h^{(2)}_{n}\left(z\right)'
def test_latex_fresnel():
from sympy.functions.special.error_functions import (fresnels, fresnelc)
from sympy.abc import z
assert latex(fresnels(z)) == r'S\left(z\right)'
assert latex(fresnelc(z)) == r'C\left(z\right)'
assert latex(fresnels(z)**2) == r'S^{2}\left(z\right)'
assert latex(fresnelc(z)**2) == r'C^{2}\left(z\right)'
def test_latex_brackets():
assert latex((-1)**x) == r"\left(-1\right)^{x}"
def test_latex_indexed():
Psi_symbol = Symbol('Psi_0', complex=True, real=False)
Psi_indexed = IndexedBase(Symbol('Psi', complex=True, real=False))
symbol_latex = latex(Psi_symbol * conjugate(Psi_symbol))
indexed_latex = latex(Psi_indexed[0] * conjugate(Psi_indexed[0]))
# \\overline{{\\Psi}_{0}} {\\Psi}_{0} vs. \\Psi_{0} \\overline{\\Psi_{0}}
assert symbol_latex == '\\Psi_{0} \\overline{\\Psi_{0}}'
assert indexed_latex == '\\overline{{\\Psi}_{0}} {\\Psi}_{0}'
# Symbol('gamma') gives r'\gamma'
assert latex(Indexed('x1',Symbol('i'))) == '{x_{1}}_{i}'
assert latex(IndexedBase('gamma')) == r'\gamma'
assert latex(IndexedBase('a b')) == 'a b'
assert latex(IndexedBase('a_b')) == 'a_{b}'
def test_latex_derivatives():
# regular "d" for ordinary derivatives
assert latex(diff(x**3, x, evaluate=False)) == \
r"\frac{d}{d x} x^{3}"
assert latex(diff(sin(x) + x**2, x, evaluate=False)) == \
r"\frac{d}{d x} \left(x^{2} + \sin{\left(x \right)}\right)"
assert latex(diff(diff(sin(x) + x**2, x, evaluate=False), evaluate=False)) == \
r"\frac{d^{2}}{d x^{2}} \left(x^{2} + \sin{\left(x \right)}\right)"
assert latex(diff(diff(diff(sin(x) + x**2, x, evaluate=False), evaluate=False), evaluate=False)) == \
r"\frac{d^{3}}{d x^{3}} \left(x^{2} + \sin{\left(x \right)}\right)"
# \partial for partial derivatives
assert latex(diff(sin(x * y), x, evaluate=False)) == \
r"\frac{\partial}{\partial x} \sin{\left(x y \right)}"
assert latex(diff(sin(x * y) + x**2, x, evaluate=False)) == \
r"\frac{\partial}{\partial x} \left(x^{2} + \sin{\left(x y \right)}\right)"
assert latex(diff(diff(sin(x*y) + x**2, x, evaluate=False), x, evaluate=False)) == \
r"\frac{\partial^{2}}{\partial x^{2}} \left(x^{2} + \sin{\left(x y \right)}\right)"
assert latex(diff(diff(diff(sin(x*y) + x**2, x, evaluate=False), x, evaluate=False), x, evaluate=False)) == \
r"\frac{\partial^{3}}{\partial x^{3}} \left(x^{2} + \sin{\left(x y \right)}\right)"
# mixed partial derivatives
f = Function("f")
assert latex(diff(diff(f(x,y), x, evaluate=False), y, evaluate=False)) == \
r"\frac{\partial^{2}}{\partial y\partial x} " + latex(f(x,y))
assert latex(diff(diff(diff(f(x,y), x, evaluate=False), x, evaluate=False), y, evaluate=False)) == \
r"\frac{\partial^{3}}{\partial y\partial x^{2}} " + latex(f(x,y))
# use ordinary d when one of the variables has been integrated out
assert latex(diff(Integral(exp(-x * y), (x, 0, oo)), y, evaluate=False)) == \
r"\frac{d}{d y} \int\limits_{0}^{\infty} e^{- x y}\, dx"
# Derivative wrapped in power:
assert latex(diff(x, x, evaluate=False)**2) == \
r"\left(\frac{d}{d x} x\right)^{2}"
assert latex(diff(f(x), x)**2) == \
r"\left(\frac{d}{d x} f{\left(x \right)}\right)^{2}"
assert latex(diff(f(x), (x, n))) == \
r"\frac{d^{n}}{d x^{n}} f{\left(x \right)}"
def test_latex_subs():
assert latex(Subs(x*y, (
x, y), (1, 2))) == r'\left. x y \right|_{\substack{ x=1\\ y=2 }}'
def test_latex_integrals():
assert latex(Integral(log(x), x)) == r"\int \log{\left(x \right)}\, dx"
assert latex(Integral(x**2, (x, 0, 1))) == r"\int\limits_{0}^{1} x^{2}\, dx"
assert latex(Integral(x**2, (x, 10, 20))) == r"\int\limits_{10}^{20} x^{2}\, dx"
assert latex(Integral(
y*x**2, (x, 0, 1), y)) == r"\int\int\limits_{0}^{1} x^{2} y\, dx\, dy"
assert latex(Integral(y*x**2, (x, 0, 1), y), mode='equation*') \
== r"\begin{equation*}\int\int\limits_{0}^{1} x^{2} y\, dx\, dy\end{equation*}"
assert latex(Integral(y*x**2, (x, 0, 1), y), mode='equation*', itex=True) \
== r"$$\int\int_{0}^{1} x^{2} y\, dx\, dy$$"
assert latex(Integral(x, (x, 0))) == r"\int\limits^{0} x\, dx"
assert latex(Integral(x*y, x, y)) == r"\iint x y\, dx\, dy"
assert latex(Integral(x*y*z, x, y, z)) == r"\iiint x y z\, dx\, dy\, dz"
assert latex(Integral(x*y*z*t, x, y, z, t)) == \
r"\iiiint t x y z\, dx\, dy\, dz\, dt"
assert latex(Integral(x, x, x, x, x, x, x)) == \
r"\int\int\int\int\int\int x\, dx\, dx\, dx\, dx\, dx\, dx"
assert latex(Integral(x, x, y, (z, 0, 1))) == \
r"\int\limits_{0}^{1}\int\int x\, dx\, dy\, dz"
# fix issue #10806
assert latex(Integral(z, z)**2) == r"\left(\int z\, dz\right)^{2}"
assert latex(Integral(x + z, z)) == r"\int \left(x + z\right)\, dz"
assert latex(Integral(x+z/2, z)) == r"\int \left(x + \frac{z}{2}\right)\, dz"
assert latex(Integral(x**y, z)) == r"\int x^{y}\, dz"
def test_latex_sets():
for s in (frozenset, set):
assert latex(s([x*y, x**2])) == r"\left\{x^{2}, x y\right\}"
assert latex(s(range(1, 6))) == r"\left\{1, 2, 3, 4, 5\right\}"
assert latex(s(range(1, 13))) == \
r"\left\{1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12\right\}"
s = FiniteSet
assert latex(s(*[x*y, x**2])) == r"\left\{x^{2}, x y\right\}"
assert latex(s(*range(1, 6))) == r"\left\{1, 2, 3, 4, 5\right\}"
assert latex(s(*range(1, 13))) == \
r"\left\{1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12\right\}"
def test_latex_SetExpr():
iv = Interval(1, 3)
se = SetExpr(iv)
assert latex(se) == r"SetExpr\left(\left[1, 3\right]\right)"
def test_latex_Range():
assert latex(Range(1, 51)) == \
r'\left\{1, 2, \ldots, 50\right\}'
assert latex(Range(1, 4)) == r'\left\{1, 2, 3\right\}'
assert latex(Range(0, 3, 1)) == r'\left\{0, 1, 2\right\}'
assert latex(Range(0, 30, 1)) == r'\left\{0, 1, \ldots, 29\right\}'
assert latex(Range(30, 1, -1)) == r'\left\{30, 29, \ldots, 2\right\}'
assert latex(Range(0, oo, 2)) == r'\left\{0, 2, \ldots, \infty\right\}'
assert latex(Range(oo, -2, -2)) == r'\left\{\infty, \ldots, 2, 0\right\}'
assert latex(Range(-2, -oo, -1)) == r'\left\{-2, -3, \ldots, -\infty\right\}'
def test_latex_sequences():
s1 = SeqFormula(a**2, (0, oo))
s2 = SeqPer((1, 2))
latex_str = r'\left[0, 1, 4, 9, \ldots\right]'
assert latex(s1) == latex_str
latex_str = r'\left[1, 2, 1, 2, \ldots\right]'
assert latex(s2) == latex_str
s3 = SeqFormula(a**2, (0, 2))
s4 = SeqPer((1, 2), (0, 2))
latex_str = r'\left[0, 1, 4\right]'
assert latex(s3) == latex_str
latex_str = r'\left[1, 2, 1\right]'
assert latex(s4) == latex_str
s5 = SeqFormula(a**2, (-oo, 0))
s6 = SeqPer((1, 2), (-oo, 0))
latex_str = r'\left[\ldots, 9, 4, 1, 0\right]'
assert latex(s5) == latex_str
latex_str = r'\left[\ldots, 2, 1, 2, 1\right]'
assert latex(s6) == latex_str
latex_str = r'\left[1, 3, 5, 11, \ldots\right]'
assert latex(SeqAdd(s1, s2)) == latex_str
latex_str = r'\left[1, 3, 5\right]'
assert latex(SeqAdd(s3, s4)) == latex_str
latex_str = r'\left[\ldots, 11, 5, 3, 1\right]'
assert latex(SeqAdd(s5, s6)) == latex_str
latex_str = r'\left[0, 2, 4, 18, \ldots\right]'
assert latex(SeqMul(s1, s2)) == latex_str
latex_str = r'\left[0, 2, 4\right]'
assert latex(SeqMul(s3, s4)) == latex_str
latex_str = r'\left[\ldots, 18, 4, 2, 0\right]'
assert latex(SeqMul(s5, s6)) == latex_str
def test_latex_FourierSeries():
latex_str = r'2 \sin{\left(x \right)} - \sin{\left(2 x \right)} + \frac{2 \sin{\left(3 x \right)}}{3} + \ldots'
assert latex(fourier_series(x, (x, -pi, pi))) == latex_str
def test_latex_FormalPowerSeries():
latex_str = r'\sum_{k=1}^{\infty} - \frac{\left(-1\right)^{- k} x^{k}}{k}'
assert latex(fps(log(1 + x))) == latex_str
def test_latex_intervals():
a = Symbol('a', real=True)
assert latex(Interval(0, 0)) == r"\left\{0\right\}"
assert latex(Interval(0, a)) == r"\left[0, a\right]"
assert latex(Interval(0, a, False, False)) == r"\left[0, a\right]"
assert latex(Interval(0, a, True, False)) == r"\left(0, a\right]"
assert latex(Interval(0, a, False, True)) == r"\left[0, a\right)"
assert latex(Interval(0, a, True, True)) == r"\left(0, a\right)"
def test_latex_AccumuBounds():
a = Symbol('a', real=True)
assert latex(AccumBounds(0, 1)) == r"\left\langle 0, 1\right\rangle"
assert latex(AccumBounds(0, a)) == r"\left\langle 0, a\right\rangle"
assert latex(AccumBounds(a + 1, a + 2)) == r"\left\langle a + 1, a + 2\right\rangle"
def test_latex_emptyset():
assert latex(S.EmptySet) == r"\emptyset"
def test_latex_commutator():
A = Operator('A')
B = Operator('B')
comm = Commutator(B, A)
assert latex(comm.doit()) == r"- (A B - B A)"
def test_latex_union():
assert latex(Union(Interval(0, 1), Interval(2, 3))) == \
r"\left[0, 1\right] \cup \left[2, 3\right]"
assert latex(Union(Interval(1, 1), Interval(2, 2), Interval(3, 4))) == \
r"\left\{1, 2\right\} \cup \left[3, 4\right]"
def test_latex_symmetric_difference():
assert latex(SymmetricDifference(Interval(2,5), Interval(4,7), \
evaluate = False)) == r'\left[2, 5\right] \triangle \left[4, 7\right]'
def test_latex_Complement():
assert latex(Complement(S.Reals, S.Naturals)) == r"\mathbb{R} \setminus \mathbb{N}"
def test_latex_Complexes():
assert latex(S.Complexes) == r"\mathbb{C}"
def test_latex_productset():
line = Interval(0, 1)
bigline = Interval(0, 10)
fset = FiniteSet(1, 2, 3)
assert latex(line**2) == r"%s^{2}" % latex(line)
assert latex(line**10) == r"%s^{10}" % latex(line)
assert latex(line * bigline * fset) == r"%s \times %s \times %s" % (
latex(line), latex(bigline), latex(fset))
def test_latex_Naturals():
assert latex(S.Naturals) == r"\mathbb{N}"
def test_latex_Naturals0():
assert latex(S.Naturals0) == r"\mathbb{N}_0"
def test_latex_Integers():
assert latex(S.Integers) == r"\mathbb{Z}"
def test_latex_ImageSet():
x = Symbol('x')
assert latex(ImageSet(Lambda(x, x**2), S.Naturals)) == \
r"\left\{x^{2}\; |\; x \in \mathbb{N}\right\}"
y = Symbol('y')
imgset = ImageSet(Lambda((x, y), x + y), {1, 2, 3}, {3, 4})
assert latex(imgset) == r"\left\{x + y\; |\; x \in \left\{1, 2, 3\right\}, y \in \left\{3, 4\right\}\right\}"
def test_latex_ConditionSet():
x = Symbol('x')
assert latex(ConditionSet(x, Eq(x**2, 1), S.Reals)) == \
r"\left\{x \mid x \in \mathbb{R} \wedge x^{2} = 1 \right\}"
assert latex(ConditionSet(x, Eq(x**2, 1), S.UniversalSet)) == \
r"\left\{x \mid x^{2} = 1 \right\}"
def test_latex_ComplexRegion():
assert latex(ComplexRegion(Interval(3, 5)*Interval(4, 6))) == \
r"\left\{x + y i\; |\; x, y \in \left[3, 5\right] \times \left[4, 6\right] \right\}"
assert latex(ComplexRegion(Interval(0, 1)*Interval(0, 2*pi), polar=True)) == \
r"\left\{r \left(i \sin{\left(\theta \right)} + \cos{\left(\theta \right)}\right)\; |\; r, \theta \in \left[0, 1\right] \times \left[0, 2 \pi\right) \right\}"
def test_latex_Contains():
x = Symbol('x')
assert latex(Contains(x, S.Naturals)) == r"x \in \mathbb{N}"
def test_latex_sum():
assert latex(Sum(x*y**2, (x, -2, 2), (y, -5, 5))) == \
r"\sum_{\substack{-2 \leq x \leq 2\\-5 \leq y \leq 5}} x y^{2}"
assert latex(Sum(x**2, (x, -2, 2))) == \
r"\sum_{x=-2}^{2} x^{2}"
assert latex(Sum(x**2 + y, (x, -2, 2))) == \
r"\sum_{x=-2}^{2} \left(x^{2} + y\right)"
assert latex(Sum(x**2 + y, (x, -2, 2))**2) == \
r"\left(\sum_{x=-2}^{2} \left(x^{2} + y\right)\right)^{2}"
def test_latex_product():
assert latex(Product(x*y**2, (x, -2, 2), (y, -5, 5))) == \
r"\prod_{\substack{-2 \leq x \leq 2\\-5 \leq y \leq 5}} x y^{2}"
assert latex(Product(x**2, (x, -2, 2))) == \
r"\prod_{x=-2}^{2} x^{2}"
assert latex(Product(x**2 + y, (x, -2, 2))) == \
r"\prod_{x=-2}^{2} \left(x^{2} + y\right)"
assert latex(Product(x, (x, -2, 2))**2) == \
r"\left(\prod_{x=-2}^{2} x\right)^{2}"
def test_latex_limits():
assert latex(Limit(x, x, oo)) == r"\lim_{x \to \infty} x"
# issue 8175
f = Function('f')
assert latex(Limit(f(x), x, 0)) == r"\lim_{x \to 0^+} f{\left(x \right)}"
assert latex(Limit(f(x), x, 0, "-")) == r"\lim_{x \to 0^-} f{\left(x \right)}"
# issue #10806
assert latex(Limit(f(x), x, 0)**2) == r"\left(\lim_{x \to 0^+} f{\left(x \right)}\right)^{2}"
# bi-directional limit
assert latex(Limit(f(x), x, 0, dir='+-')) == r"\lim_{x \to 0} f{\left(x \right)}"
def test_latex_log():
assert latex(log(x)) == r"\log{\left(x \right)}"
assert latex(ln(x)) == r"\log{\left(x \right)}"
assert latex(log(x), ln_notation=True) == r"\ln{\left(x \right)}"
assert latex(log(x)+log(y)) == r"\log{\left(x \right)} + \log{\left(y \right)}"
assert latex(log(x)+log(y), ln_notation=True) == r"\ln{\left(x \right)} + \ln{\left(y \right)}"
assert latex(pow(log(x),x)) == r"\log{\left(x \right)}^{x}"
assert latex(pow(log(x),x), ln_notation=True) == r"\ln{\left(x \right)}^{x}"
def test_issue_3568():
beta = Symbol(r'\beta')
y = beta + x
assert latex(y) in [r'\beta + x', r'x + \beta']
beta = Symbol(r'beta')
y = beta + x
assert latex(y) in [r'\beta + x', r'x + \beta']
def test_latex():
assert latex((2*tau)**Rational(7, 2)) == "8 \\sqrt{2} \\tau^{\\frac{7}{2}}"
assert latex((2*mu)**Rational(7, 2), mode='equation*') == \
"\\begin{equation*}8 \\sqrt{2} \\mu^{\\frac{7}{2}}\\end{equation*}"
assert latex((2*mu)**Rational(7, 2), mode='equation', itex=True) == \
"$$8 \\sqrt{2} \\mu^{\\frac{7}{2}}$$"
assert latex([2/x, y]) == r"\left[ \frac{2}{x}, \quad y\right]"
def test_latex_dict():
d = {Rational(1): 1, x**2: 2, x: 3, x**3: 4}
assert latex(d) == r'\left\{ 1 : 1, \quad x : 3, \quad x^{2} : 2, \quad x^{3} : 4\right\}'
D = Dict(d)
assert latex(D) == r'\left\{ 1 : 1, \quad x : 3, \quad x^{2} : 2, \quad x^{3} : 4\right\}'
def test_latex_list():
l = [Symbol('omega1'), Symbol('a'), Symbol('alpha')]
assert latex(l) == r'\left[ \omega_{1}, \quad a, \quad \alpha\right]'
def test_latex_rational():
#tests issue 3973
assert latex(-Rational(1, 2)) == "- \\frac{1}{2}"
assert latex(Rational(-1, 2)) == "- \\frac{1}{2}"
assert latex(Rational(1, -2)) == "- \\frac{1}{2}"
assert latex(-Rational(-1, 2)) == "\\frac{1}{2}"
assert latex(-Rational(1, 2)*x) == "- \\frac{x}{2}"
assert latex(-Rational(1, 2)*x + Rational(-2, 3)*y) == \
"- \\frac{x}{2} - \\frac{2 y}{3}"
def test_latex_inverse():
#tests issue 4129
assert latex(1/x) == "\\frac{1}{x}"
assert latex(1/(x + y)) == "\\frac{1}{x + y}"
def test_latex_DiracDelta():
assert latex(DiracDelta(x)) == r"\delta\left(x\right)"
assert latex(DiracDelta(x)**2) == r"\left(\delta\left(x\right)\right)^{2}"
assert latex(DiracDelta(x, 0)) == r"\delta\left(x\right)"
assert latex(DiracDelta(x, 5)) == \
r"\delta^{\left( 5 \right)}\left( x \right)"
assert latex(DiracDelta(x, 5)**2) == \
r"\left(\delta^{\left( 5 \right)}\left( x \right)\right)^{2}"
def test_latex_Heaviside():
assert latex(Heaviside(x)) == r"\theta\left(x\right)"
assert latex(Heaviside(x)**2) == r"\left(\theta\left(x\right)\right)^{2}"
def test_latex_KroneckerDelta():
assert latex(KroneckerDelta(x, y)) == r"\delta_{x y}"
assert latex(KroneckerDelta(x, y + 1)) == r"\delta_{x, y + 1}"
# issue 6578
assert latex(KroneckerDelta(x + 1, y)) == r"\delta_{y, x + 1}"
def test_latex_LeviCivita():
assert latex(LeviCivita(x, y, z)) == r"\varepsilon_{x y z}"
assert latex(LeviCivita(x, y, z)**2) == r"\left(\varepsilon_{x y z}\right)^{2}"
assert latex(LeviCivita(x, y, z + 1)) == r"\varepsilon_{x, y, z + 1}"
assert latex(LeviCivita(x, y + 1, z)) == r"\varepsilon_{x, y + 1, z}"
assert latex(LeviCivita(x + 1, y, z)) == r"\varepsilon_{x + 1, y, z}"
def test_mode():
expr = x + y
assert latex(expr) == 'x + y'
assert latex(expr, mode='plain') == 'x + y'
assert latex(expr, mode='inline') == '$x + y$'
assert latex(
expr, mode='equation*') == '\\begin{equation*}x + y\\end{equation*}'
assert latex(
expr, mode='equation') == '\\begin{equation}x + y\\end{equation}'
def test_latex_Piecewise():
p = Piecewise((x, x < 1), (x**2, True))
assert latex(p) == "\\begin{cases} x & \\text{for}\\: x < 1 \\\\x^{2} &" \
" \\text{otherwise} \\end{cases}"
assert latex(p, itex=True) == "\\begin{cases} x & \\text{for}\\: x \\lt 1 \\\\x^{2} &" \
" \\text{otherwise} \\end{cases}"
p = Piecewise((x, x < 0), (0, x >= 0))
assert latex(p) == '\\begin{cases} x & \\text{for}\\: x < 0 \\\\0 &' \
' \\text{otherwise} \\end{cases}'
A, B = symbols("A B", commutative=False)
p = Piecewise((A**2, Eq(A, B)), (A*B, True))
s = r"\begin{cases} A^{2} & \text{for}\: A = B \\A B & \text{otherwise} \end{cases}"
assert latex(p) == s
assert latex(A*p) == r"A \left(%s\right)" % s
assert latex(p*A) == r"\left(%s\right) A" % s
def test_latex_Matrix():
M = Matrix([[1 + x, y], [y, x - 1]])
assert latex(M) == \
r'\left[\begin{matrix}x + 1 & y\\y & x - 1\end{matrix}\right]'
assert latex(M, mode='inline') == \
r'$\left[\begin{smallmatrix}x + 1 & y\\' \
r'y & x - 1\end{smallmatrix}\right]$'
assert latex(M, mat_str='array') == \
r'\left[\begin{array}{cc}x + 1 & y\\y & x - 1\end{array}\right]'
assert latex(M, mat_str='bmatrix') == \
r'\left[\begin{bmatrix}x + 1 & y\\y & x - 1\end{bmatrix}\right]'
assert latex(M, mat_delim=None, mat_str='bmatrix') == \
r'\begin{bmatrix}x + 1 & y\\y & x - 1\end{bmatrix}'
M2 = Matrix(1, 11, range(11))
assert latex(M2) == \
r'\left[\begin{array}{ccccccccccc}' \
r'0 & 1 & 2 & 3 & 4 & 5 & 6 & 7 & 8 & 9 & 10\end{array}\right]'
def test_latex_matrix_with_functions():
t = symbols('t')
theta1 = symbols('theta1', cls=Function)
M = Matrix([[sin(theta1(t)), cos(theta1(t))],
[cos(theta1(t).diff(t)), sin(theta1(t).diff(t))]])
expected = (r'\left[\begin{matrix}\sin{\left('
r'\theta_{1}{\left(t \right)} \right)} & '
r'\cos{\left(\theta_{1}{\left(t \right)} \right)'
r'}\\\cos{\left(\frac{d}{d t} \theta_{1}{\left(t '
r'\right)} \right)} & \sin{\left(\frac{d}{d t} '
r'\theta_{1}{\left(t \right)} \right'
r')}\end{matrix}\right]')
assert latex(M) == expected
def test_latex_NDimArray():
x, y, z, w = symbols("x y z w")
for ArrayType in (ImmutableDenseNDimArray, ImmutableSparseNDimArray, MutableDenseNDimArray, MutableSparseNDimArray):
# Basic: scalar array
M = ArrayType(x)
assert latex(M) == "x"
M = ArrayType([[1 / x, y], [z, w]])
M1 = ArrayType([1 / x, y, z])
M2 = tensorproduct(M1, M)
M3 = tensorproduct(M, M)
assert latex(M) == '\\left[\\begin{matrix}\\frac{1}{x} & y\\\\z & w\\end{matrix}\\right]'
assert latex(M1) == "\\left[\\begin{matrix}\\frac{1}{x} & y & z\\end{matrix}\\right]"
assert latex(M2) == r"\left[\begin{matrix}" \
r"\left[\begin{matrix}\frac{1}{x^{2}} & \frac{y}{x}\\\frac{z}{x} & \frac{w}{x}\end{matrix}\right] & " \
r"\left[\begin{matrix}\frac{y}{x} & y^{2}\\y z & w y\end{matrix}\right] & " \
r"\left[\begin{matrix}\frac{z}{x} & y z\\z^{2} & w z\end{matrix}\right]" \
r"\end{matrix}\right]"
assert latex(M3) == r"""\left[\begin{matrix}"""\
r"""\left[\begin{matrix}\frac{1}{x^{2}} & \frac{y}{x}\\\frac{z}{x} & \frac{w}{x}\end{matrix}\right] & """\
r"""\left[\begin{matrix}\frac{y}{x} & y^{2}\\y z & w y\end{matrix}\right]\\"""\
r"""\left[\begin{matrix}\frac{z}{x} & y z\\z^{2} & w z\end{matrix}\right] & """\
r"""\left[\begin{matrix}\frac{w}{x} & w y\\w z & w^{2}\end{matrix}\right]"""\
r"""\end{matrix}\right]"""
Mrow = ArrayType([[x, y, 1/z]])
Mcolumn = ArrayType([[x], [y], [1/z]])
Mcol2 = ArrayType([Mcolumn.tolist()])
assert latex(Mrow) == r"\left[\left[\begin{matrix}x & y & \frac{1}{z}\end{matrix}\right]\right]"
assert latex(Mcolumn) == r"\left[\begin{matrix}x\\y\\\frac{1}{z}\end{matrix}\right]"
assert latex(Mcol2) == r'\left[\begin{matrix}\left[\begin{matrix}x\\y\\\frac{1}{z}\end{matrix}\right]\end{matrix}\right]'
def test_latex_mul_symbol():
assert latex(4*4**x, mul_symbol='times') == "4 \\times 4^{x}"
assert latex(4*4**x, mul_symbol='dot') == "4 \\cdot 4^{x}"
assert latex(4*4**x, mul_symbol='ldot') == r"4 \,.\, 4^{x}"
assert latex(4*x, mul_symbol='times') == "4 \\times x"
assert latex(4*x, mul_symbol='dot') == "4 \\cdot x"
assert latex(4*x, mul_symbol='ldot') == r"4 \,.\, x"
def test_latex_issue_4381():
y = 4*4**log(2)
assert latex(y) == r'4 \cdot 4^{\log{\left(2 \right)}}'
assert latex(1/y) == r'\frac{1}{4 \cdot 4^{\log{\left(2 \right)}}}'
def test_latex_issue_4576():
assert latex(Symbol("beta_13_2")) == r"\beta_{13 2}"
assert latex(Symbol("beta_132_20")) == r"\beta_{132 20}"
assert latex(Symbol("beta_13")) == r"\beta_{13}"
assert latex(Symbol("x_a_b")) == r"x_{a b}"
assert latex(Symbol("x_1_2_3")) == r"x_{1 2 3}"
assert latex(Symbol("x_a_b1")) == r"x_{a b1}"
assert latex(Symbol("x_a_1")) == r"x_{a 1}"
assert latex(Symbol("x_1_a")) == r"x_{1 a}"
assert latex(Symbol("x_1^aa")) == r"x^{aa}_{1}"
assert latex(Symbol("x_1__aa")) == r"x^{aa}_{1}"
assert latex(Symbol("x_11^a")) == r"x^{a}_{11}"
assert latex(Symbol("x_11__a")) == r"x^{a}_{11}"
assert latex(Symbol("x_a_a_a_a")) == r"x_{a a a a}"
assert latex(Symbol("x_a_a^a^a")) == r"x^{a a}_{a a}"
assert latex(Symbol("x_a_a__a__a")) == r"x^{a a}_{a a}"
assert latex(Symbol("alpha_11")) == r"\alpha_{11}"
assert latex(Symbol("alpha_11_11")) == r"\alpha_{11 11}"
assert latex(Symbol("alpha_alpha")) == r"\alpha_{\alpha}"
assert latex(Symbol("alpha^aleph")) == r"\alpha^{\aleph}"
assert latex(Symbol("alpha__aleph")) == r"\alpha^{\aleph}"
def test_latex_pow_fraction():
x = Symbol('x')
# Testing exp
assert 'e^{-x}' in latex(exp(-x)/2).replace(' ', '') # Remove Whitespace
# Testing just e^{-x} in case future changes alter behavior of muls or fracs
# In particular current output is \frac{1}{2}e^{- x} but perhaps this will
# change to \frac{e^{-x}}{2}
# Testing general, non-exp, power
assert '3^{-x}' in latex(3**-x/2).replace(' ', '')
def test_noncommutative():
A, B, C = symbols('A,B,C', commutative=False)
assert latex(A*B*C**-1) == "A B C^{-1}"
assert latex(C**-1*A*B) == "C^{-1} A B"
assert latex(A*C**-1*B) == "A C^{-1} B"
def test_latex_order():
expr = x**3 + x**2*y + 3*x*y**3 + y**4
assert latex(expr, order='lex') == "x^{3} + x^{2} y + 3 x y^{3} + y^{4}"
assert latex(
expr, order='rev-lex') == "y^{4} + 3 x y^{3} + x^{2} y + x^{3}"
def test_latex_Lambda():
assert latex(Lambda(x, x + 1)) == \
r"\left( x \mapsto x + 1 \right)"
assert latex(Lambda((x, y), x + 1)) == \
r"\left( \left( x, \quad y\right) \mapsto x + 1 \right)"
def test_latex_PolyElement():
Ruv, u,v = ring("u,v", ZZ)
Rxyz, x,y,z = ring("x,y,z", Ruv)
assert latex(x - x) == r"0"
assert latex(x - 1) == r"x - 1"
assert latex(x + 1) == r"x + 1"
assert latex((u**2 + 3*u*v + 1)*x**2*y + u + 1) == r"\left({u}^{2} + 3 u v + 1\right) {x}^{2} y + u + 1"
assert latex((u**2 + 3*u*v + 1)*x**2*y + (u + 1)*x) == r"\left({u}^{2} + 3 u v + 1\right) {x}^{2} y + \left(u + 1\right) x"
assert latex((u**2 + 3*u*v + 1)*x**2*y + (u + 1)*x + 1) == r"\left({u}^{2} + 3 u v + 1\right) {x}^{2} y + \left(u + 1\right) x + 1"
assert latex((-u**2 + 3*u*v - 1)*x**2*y - (u + 1)*x - 1) == r"-\left({u}^{2} - 3 u v + 1\right) {x}^{2} y - \left(u + 1\right) x - 1"
assert latex(-(v**2 + v + 1)*x + 3*u*v + 1) == r"-\left({v}^{2} + v + 1\right) x + 3 u v + 1"
assert latex(-(v**2 + v + 1)*x - 3*u*v + 1) == r"-\left({v}^{2} + v + 1\right) x - 3 u v + 1"
def test_latex_FracElement():
Fuv, u,v = field("u,v", ZZ)
Fxyzt, x,y,z,t = field("x,y,z,t", Fuv)
assert latex(x - x) == r"0"
assert latex(x - 1) == r"x - 1"
assert latex(x + 1) == r"x + 1"
assert latex(x/3) == r"\frac{x}{3}"
assert latex(x/z) == r"\frac{x}{z}"
assert latex(x*y/z) == r"\frac{x y}{z}"
assert latex(x/(z*t)) == r"\frac{x}{z t}"
assert latex(x*y/(z*t)) == r"\frac{x y}{z t}"
assert latex((x - 1)/y) == r"\frac{x - 1}{y}"
assert latex((x + 1)/y) == r"\frac{x + 1}{y}"
assert latex((-x - 1)/y) == r"\frac{-x - 1}{y}"
assert latex((x + 1)/(y*z)) == r"\frac{x + 1}{y z}"
assert latex(-y/(x + 1)) == r"\frac{-y}{x + 1}"
assert latex(y*z/(x + 1)) == r"\frac{y z}{x + 1}"
assert latex(((u + 1)*x*y + 1)/((v - 1)*z - 1)) == r"\frac{\left(u + 1\right) x y + 1}{\left(v - 1\right) z - 1}"
assert latex(((u + 1)*x*y + 1)/((v - 1)*z - t*u*v - 1)) == r"\frac{\left(u + 1\right) x y + 1}{\left(v - 1\right) z - u v t - 1}"
def test_latex_Poly():
assert latex(Poly(x**2 + 2 * x, x)) == \
r"\operatorname{Poly}{\left( x^{2} + 2 x, x, domain=\mathbb{Z} \right)}"
assert latex(Poly(x/y, x)) == \
r"\operatorname{Poly}{\left( \frac{1}{y} x, x, domain=\mathbb{Z}\left(y\right) \right)}"
assert latex(Poly(2.0*x + y)) == \
r"\operatorname{Poly}{\left( 2.0 x + 1.0 y, x, y, domain=\mathbb{R} \right)}"
def test_latex_Poly_order():
assert latex(Poly([a, 1, b, 2, c, 3], x)) == \
'\\operatorname{Poly}{\\left( a x^{5} + x^{4} + b x^{3} + 2 x^{2} + c x + 3, x, domain=\\mathbb{Z}\\left[a, b, c\\right] \\right)}'
assert latex(Poly([a, 1, b+c, 2, 3], x)) == \
'\\operatorname{Poly}{\\left( a x^{4} + x^{3} + \\left(b + c\\right) x^{2} + 2 x + 3, x, domain=\\mathbb{Z}\\left[a, b, c\\right] \\right)}'
assert latex(Poly(a*x**3 + x**2*y - x*y - c*y**3 - b*x*y**2 + y - a*x + b, (x, y))) == \
'\\operatorname{Poly}{\\left( a x^{3} + x^{2}y - b xy^{2} - xy - a x - c y^{3} + y + b, x, y, domain=\\mathbb{Z}\\left[a, b, c\\right] \\right)}'
def test_latex_ComplexRootOf():
assert latex(rootof(x**5 + x + 3, 0)) == \
r"\operatorname{CRootOf} {\left(x^{5} + x + 3, 0\right)}"
def test_latex_RootSum():
assert latex(RootSum(x**5 + x + 3, sin)) == \
r"\operatorname{RootSum} {\left(x^{5} + x + 3, \left( x \mapsto \sin{\left(x \right)} \right)\right)}"
def test_settings():
raises(TypeError, lambda: latex(x*y, method="garbage"))
def test_latex_numbers():
assert latex(catalan(n)) == r"C_{n}"
assert latex(catalan(n)**2) == r"C_{n}^{2}"
def test_latex_euler():
assert latex(euler(n)) == r"E_{n}"
assert latex(euler(n, x)) == r"E_{n}\left(x\right)"
assert latex(euler(n, x)**2) == r"E_{n}^{2}\left(x\right)"
def test_lamda():
assert latex(Symbol('lamda')) == r"\lambda"
assert latex(Symbol('Lamda')) == r"\Lambda"
def test_custom_symbol_names():
x = Symbol('x')
y = Symbol('y')
assert latex(x) == "x"
assert latex(x, symbol_names={x: "x_i"}) == "x_i"
assert latex(x + y, symbol_names={x: "x_i"}) == "x_i + y"
assert latex(x**2, symbol_names={x: "x_i"}) == "x_i^{2}"
assert latex(x + y, symbol_names={x: "x_i", y: "y_j"}) == "x_i + y_j"
def test_matAdd():
from sympy import MatrixSymbol
from sympy.printing.latex import LatexPrinter
C = MatrixSymbol('C', 5, 5)
B = MatrixSymbol('B', 5, 5)
l = LatexPrinter()
assert l._print(C - 2*B) in ['- 2 B + C', 'C -2 B']
assert l._print(C + 2*B) in ['2 B + C', 'C + 2 B']
assert l._print(B - 2*C) in ['B - 2 C', '- 2 C + B']
assert l._print(B + 2*C) in ['B + 2 C', '2 C + B']
def test_matMul():
from sympy import MatrixSymbol
from sympy.printing.latex import LatexPrinter
A = MatrixSymbol('A', 5, 5)
B = MatrixSymbol('B', 5, 5)
x = Symbol('x')
l = LatexPrinter()
assert l._print_MatMul(2*A) == '2 A'
assert l._print_MatMul(2*x*A) == '2 x A'
assert l._print_MatMul(-2*A) == '- 2 A'
assert l._print_MatMul(1.5*A) == '1.5 A'
assert l._print_MatMul(sqrt(2)*A) == r'\sqrt{2} A'
assert l._print_MatMul(-sqrt(2)*A) == r'- \sqrt{2} A'
assert l._print_MatMul(2*sqrt(2)*x*A) == r'2 \sqrt{2} x A'
assert l._print_MatMul(-2*A*(A + 2*B)) in [r'- 2 A \left(A + 2 B\right)',
r'- 2 A \left(2 B + A\right)']
def test_latex_MatrixSlice():
from sympy.matrices.expressions import MatrixSymbol
assert latex(MatrixSymbol('X', 10, 10)[:5, 1:9:2]) == \
r'X\left[:5, 1:9:2\right]'
assert latex(MatrixSymbol('X', 10, 10)[5, :5:2]) == \
r'X\left[5, :5:2\right]'
def test_latex_RandomDomain():
from sympy.stats import Normal, Die, Exponential, pspace, where
X = Normal('x1', 0, 1)
assert latex(where(X > 0)) == r"Domain: 0 < x_{1} \wedge x_{1} < \infty"
D = Die('d1', 6)
assert latex(where(D > 4)) == r"Domain: d_{1} = 5 \vee d_{1} = 6"
A = Exponential('a', 1)
B = Exponential('b', 1)
assert latex(
pspace(Tuple(A, B)).domain) == \
r"Domain: 0 \leq a \wedge 0 \leq b \wedge a < \infty \wedge b < \infty"
def test_PrettyPoly():
from sympy.polys.domains import QQ
F = QQ.frac_field(x, y)
R = QQ[x, y]
assert latex(F.convert(x/(x + y))) == latex(x/(x + y))
assert latex(R.convert(x + y)) == latex(x + y)
def test_integral_transforms():
x = Symbol("x")
k = Symbol("k")
f = Function("f")
a = Symbol("a")
b = Symbol("b")
assert latex(MellinTransform(f(x), x, k)) == r"\mathcal{M}_{x}\left[f{\left(x \right)}\right]\left(k\right)"
assert latex(InverseMellinTransform(f(k), k, x, a, b)) == r"\mathcal{M}^{-1}_{k}\left[f{\left(k \right)}\right]\left(x\right)"
assert latex(LaplaceTransform(f(x), x, k)) == r"\mathcal{L}_{x}\left[f{\left(x \right)}\right]\left(k\right)"
assert latex(InverseLaplaceTransform(f(k), k, x, (a, b))) == r"\mathcal{L}^{-1}_{k}\left[f{\left(k \right)}\right]\left(x\right)"
assert latex(FourierTransform(f(x), x, k)) == r"\mathcal{F}_{x}\left[f{\left(x \right)}\right]\left(k\right)"
assert latex(InverseFourierTransform(f(k), k, x)) == r"\mathcal{F}^{-1}_{k}\left[f{\left(k \right)}\right]\left(x\right)"
assert latex(CosineTransform(f(x), x, k)) == r"\mathcal{COS}_{x}\left[f{\left(x \right)}\right]\left(k\right)"
assert latex(InverseCosineTransform(f(k), k, x)) == r"\mathcal{COS}^{-1}_{k}\left[f{\left(k \right)}\right]\left(x\right)"
assert latex(SineTransform(f(x), x, k)) == r"\mathcal{SIN}_{x}\left[f{\left(x \right)}\right]\left(k\right)"
assert latex(InverseSineTransform(f(k), k, x)) == r"\mathcal{SIN}^{-1}_{k}\left[f{\left(k \right)}\right]\left(x\right)"
def test_PolynomialRingBase():
from sympy.polys.domains import QQ
assert latex(QQ.old_poly_ring(x, y)) == r"\mathbb{Q}\left[x, y\right]"
assert latex(QQ.old_poly_ring(x, y, order="ilex")) == \
r"S_<^{-1}\mathbb{Q}\left[x, y\right]"
def test_categories():
from sympy.categories import (Object, IdentityMorphism,
NamedMorphism, Category, Diagram, DiagramGrid)
A1 = Object("A1")
A2 = Object("A2")
A3 = Object("A3")
f1 = NamedMorphism(A1, A2, "f1")
f2 = NamedMorphism(A2, A3, "f2")
id_A1 = IdentityMorphism(A1)
K1 = Category("K1")
assert latex(A1) == "A_{1}"
assert latex(f1) == "f_{1}:A_{1}\\rightarrow A_{2}"
assert latex(id_A1) == "id:A_{1}\\rightarrow A_{1}"
assert latex(f2*f1) == "f_{2}\\circ f_{1}:A_{1}\\rightarrow A_{3}"
assert latex(K1) == r"\mathbf{K_{1}}"
d = Diagram()
assert latex(d) == r"\emptyset"
d = Diagram({f1: "unique", f2: S.EmptySet})
assert latex(d) == r"\left\{ f_{2}\circ f_{1}:A_{1}" \
r"\rightarrow A_{3} : \emptyset, \quad id:A_{1}\rightarrow " \
r"A_{1} : \emptyset, \quad id:A_{2}\rightarrow A_{2} : " \
r"\emptyset, \quad id:A_{3}\rightarrow A_{3} : \emptyset, " \
r"\quad f_{1}:A_{1}\rightarrow A_{2} : \left\{unique\right\}, " \
r"\quad f_{2}:A_{2}\rightarrow A_{3} : \emptyset\right\}"
d = Diagram({f1: "unique", f2: S.EmptySet}, {f2 * f1: "unique"})
assert latex(d) == r"\left\{ f_{2}\circ f_{1}:A_{1}" \
r"\rightarrow A_{3} : \emptyset, \quad id:A_{1}\rightarrow " \
r"A_{1} : \emptyset, \quad id:A_{2}\rightarrow A_{2} : " \
r"\emptyset, \quad id:A_{3}\rightarrow A_{3} : \emptyset, " \
r"\quad f_{1}:A_{1}\rightarrow A_{2} : \left\{unique\right\}," \
r" \quad f_{2}:A_{2}\rightarrow A_{3} : \emptyset\right\}" \
r"\Longrightarrow \left\{ f_{2}\circ f_{1}:A_{1}" \
r"\rightarrow A_{3} : \left\{unique\right\}\right\}"
# A linear diagram.
A = Object("A")
B = Object("B")
C = Object("C")
f = NamedMorphism(A, B, "f")
g = NamedMorphism(B, C, "g")
d = Diagram([f, g])
grid = DiagramGrid(d)
assert latex(grid) == "\\begin{array}{cc}\n" \
"A & B \\\\\n" \
" & C \n" \
"\\end{array}\n"
def test_Modules():
from sympy.polys.domains import QQ
from sympy.polys.agca import homomorphism
R = QQ.old_poly_ring(x, y)
F = R.free_module(2)
M = F.submodule([x, y], [1, x**2])
assert latex(F) == r"{\mathbb{Q}\left[x, y\right]}^{2}"
assert latex(M) == \
r"\left\langle {\left[ {x},{y} \right]},{\left[ {1},{x^{2}} \right]} \right\rangle"
I = R.ideal(x**2, y)
assert latex(I) == r"\left\langle {x^{2}},{y} \right\rangle"
Q = F / M
assert latex(Q) == r"\frac{{\mathbb{Q}\left[x, y\right]}^{2}}{\left\langle {\left[ {x},{y} \right]},{\left[ {1},{x^{2}} \right]} \right\rangle}"
assert latex(Q.submodule([1, x**3/2], [2, y])) == \
r"\left\langle {{\left[ {1},{\frac{x^{3}}{2}} \right]} + {\left\langle {\left[ {x},{y} \right]},{\left[ {1},{x^{2}} \right]} \right\rangle}},{{\left[ {2},{y} \right]} + {\left\langle {\left[ {x},{y} \right]},{\left[ {1},{x^{2}} \right]} \right\rangle}} \right\rangle"
h = homomorphism(QQ.old_poly_ring(x).free_module(2), QQ.old_poly_ring(x).free_module(2), [0, 0])
assert latex(h) == r"{\left[\begin{matrix}0 & 0\\0 & 0\end{matrix}\right]} : {{\mathbb{Q}\left[x\right]}^{2}} \to {{\mathbb{Q}\left[x\right]}^{2}}"
def test_QuotientRing():
from sympy.polys.domains import QQ
R = QQ.old_poly_ring(x)/[x**2 + 1]
assert latex(
R) == r"\frac{\mathbb{Q}\left[x\right]}{\left\langle {x^{2} + 1} \right\rangle}"
assert latex(R.one) == r"{1} + {\left\langle {x^{2} + 1} \right\rangle}"
def test_Tr():
#TODO: Handle indices
A, B = symbols('A B', commutative=False)
t = Tr(A*B)
assert latex(t) == r'\mbox{Tr}\left(A B\right)'
def test_Adjoint():
from sympy.matrices import MatrixSymbol, Adjoint, Inverse, Transpose
X = MatrixSymbol('X', 2, 2)
Y = MatrixSymbol('Y', 2, 2)
assert latex(Adjoint(X)) == r'X^\dagger'
assert latex(Adjoint(X + Y)) == r'\left(X + Y\right)^\dagger'
assert latex(Adjoint(X) + Adjoint(Y)) == r'X^\dagger + Y^\dagger'
assert latex(Adjoint(X*Y)) == r'\left(X Y\right)^\dagger'
assert latex(Adjoint(Y)*Adjoint(X)) == r'Y^\dagger X^\dagger'
assert latex(Adjoint(X**2)) == r'\left(X^{2}\right)^\dagger'
assert latex(Adjoint(X)**2) == r'\left(X^\dagger\right)^{2}'
assert latex(Adjoint(Inverse(X))) == r'\left(X^{-1}\right)^\dagger'
assert latex(Inverse(Adjoint(X))) == r'\left(X^\dagger\right)^{-1}'
assert latex(Adjoint(Transpose(X))) == r'\left(X^T\right)^\dagger'
assert latex(Transpose(Adjoint(X))) == r'\left(X^\dagger\right)^T'
def test_Hadamard():
from sympy.matrices import MatrixSymbol, HadamardProduct
X = MatrixSymbol('X', 2, 2)
Y = MatrixSymbol('Y', 2, 2)
assert latex(HadamardProduct(X, Y*Y)) == r'X \circ Y^{2}'
assert latex(HadamardProduct(X, Y)*Y) == r'\left(X \circ Y\right) Y'
def test_ZeroMatrix():
from sympy import ZeroMatrix
assert latex(ZeroMatrix(1, 1)) == r"\mathbb{0}"
def test_boolean_args_order():
syms = symbols('a:f')
expr = And(*syms)
assert latex(expr) == 'a \\wedge b \\wedge c \\wedge d \\wedge e \\wedge f'
expr = Or(*syms)
assert latex(expr) == 'a \\vee b \\vee c \\vee d \\vee e \\vee f'
expr = Equivalent(*syms)
assert latex(expr) == 'a \\Leftrightarrow b \\Leftrightarrow c \\Leftrightarrow d \\Leftrightarrow e \\Leftrightarrow f'
expr = Xor(*syms)
assert latex(expr) == 'a \\veebar b \\veebar c \\veebar d \\veebar e \\veebar f'
def test_imaginary():
i = sqrt(-1)
assert latex(i) == r'i'
def test_builtins_without_args():
assert latex(sin) == r'\sin'
assert latex(cos) == r'\cos'
assert latex(tan) == r'\tan'
assert latex(log) == r'\log'
assert latex(Ei) == r'\operatorname{Ei}'
assert latex(zeta) == r'\zeta'
def test_latex_greek_functions():
# bug because capital greeks that have roman equivalents should not use
# \Alpha, \Beta, \Eta, etc.
s = Function('Alpha')
assert latex(s) == r'A'
assert latex(s(x)) == r'A{\left(x \right)}'
s = Function('Beta')
assert latex(s) == r'B'
s = Function('Eta')
assert latex(s) == r'H'
assert latex(s(x)) == r'H{\left(x \right)}'
# bug because sympy.core.numbers.Pi is special
p = Function('Pi')
# assert latex(p(x)) == r'\Pi{\left(x \right)}'
assert latex(p) == r'\Pi'
# bug because not all greeks are included
c = Function('chi')
assert latex(c(x)) == r'\chi{\left(x \right)}'
assert latex(c) == r'\chi'
def test_translate():
s = 'Alpha'
assert translate(s) == 'A'
s = 'Beta'
assert translate(s) == 'B'
s = 'Eta'
assert translate(s) == 'H'
s = 'omicron'
assert translate(s) == 'o'
s = 'Pi'
assert translate(s) == r'\Pi'
s = 'pi'
assert translate(s) == r'\pi'
s = 'LamdaHatDOT'
assert translate(s) == r'\dot{\hat{\Lambda}}'
def test_other_symbols():
from sympy.printing.latex import other_symbols
for s in other_symbols:
assert latex(symbols(s)) == "\\"+s
def test_modifiers():
# Test each modifier individually in the simplest case (with funny capitalizations)
assert latex(symbols("xMathring")) == r"\mathring{x}"
assert latex(symbols("xCheck")) == r"\check{x}"
assert latex(symbols("xBreve")) == r"\breve{x}"
assert latex(symbols("xAcute")) == r"\acute{x}"
assert latex(symbols("xGrave")) == r"\grave{x}"
assert latex(symbols("xTilde")) == r"\tilde{x}"
assert latex(symbols("xPrime")) == r"{x}'"
assert latex(symbols("xddDDot")) == r"\ddddot{x}"
assert latex(symbols("xDdDot")) == r"\dddot{x}"
assert latex(symbols("xDDot")) == r"\ddot{x}"
assert latex(symbols("xBold")) == r"\boldsymbol{x}"
assert latex(symbols("xnOrM")) == r"\left\|{x}\right\|"
assert latex(symbols("xAVG")) == r"\left\langle{x}\right\rangle"
assert latex(symbols("xHat")) == r"\hat{x}"
assert latex(symbols("xDot")) == r"\dot{x}"
assert latex(symbols("xBar")) == r"\bar{x}"
assert latex(symbols("xVec")) == r"\vec{x}"
assert latex(symbols("xAbs")) == r"\left|{x}\right|"
assert latex(symbols("xMag")) == r"\left|{x}\right|"
assert latex(symbols("xPrM")) == r"{x}'"
assert latex(symbols("xBM")) == r"\boldsymbol{x}"
# Test strings that are *only* the names of modifiers
assert latex(symbols("Mathring")) == r"Mathring"
assert latex(symbols("Check")) == r"Check"
assert latex(symbols("Breve")) == r"Breve"
assert latex(symbols("Acute")) == r"Acute"
assert latex(symbols("Grave")) == r"Grave"
assert latex(symbols("Tilde")) == r"Tilde"
assert latex(symbols("Prime")) == r"Prime"
assert latex(symbols("DDot")) == r"\dot{D}"
assert latex(symbols("Bold")) == r"Bold"
assert latex(symbols("NORm")) == r"NORm"
assert latex(symbols("AVG")) == r"AVG"
assert latex(symbols("Hat")) == r"Hat"
assert latex(symbols("Dot")) == r"Dot"
assert latex(symbols("Bar")) == r"Bar"
assert latex(symbols("Vec")) == r"Vec"
assert latex(symbols("Abs")) == r"Abs"
assert latex(symbols("Mag")) == r"Mag"
assert latex(symbols("PrM")) == r"PrM"
assert latex(symbols("BM")) == r"BM"
assert latex(symbols("hbar")) == r"\hbar"
# Check a few combinations
assert latex(symbols("xvecdot")) == r"\dot{\vec{x}}"
assert latex(symbols("xDotVec")) == r"\vec{\dot{x}}"
assert latex(symbols("xHATNorm")) == r"\left\|{\hat{x}}\right\|"
# Check a couple big, ugly combinations
assert latex(symbols('xMathringBm_yCheckPRM__zbreveAbs')) == r"\boldsymbol{\mathring{x}}^{\left|{\breve{z}}\right|}_{{\check{y}}'}"
assert latex(symbols('alphadothat_nVECDOT__tTildePrime')) == r"\hat{\dot{\alpha}}^{{\tilde{t}}'}_{\dot{\vec{n}}}"
def test_greek_symbols():
assert latex(Symbol('alpha')) == r'\alpha'
assert latex(Symbol('beta')) == r'\beta'
assert latex(Symbol('gamma')) == r'\gamma'
assert latex(Symbol('delta')) == r'\delta'
assert latex(Symbol('epsilon')) == r'\epsilon'
assert latex(Symbol('zeta')) == r'\zeta'
assert latex(Symbol('eta')) == r'\eta'
assert latex(Symbol('theta')) == r'\theta'
assert latex(Symbol('iota')) == r'\iota'
assert latex(Symbol('kappa')) == r'\kappa'
assert latex(Symbol('lambda')) == r'\lambda'
assert latex(Symbol('mu')) == r'\mu'
assert latex(Symbol('nu')) == r'\nu'
assert latex(Symbol('xi')) == r'\xi'
assert latex(Symbol('omicron')) == r'o'
assert latex(Symbol('pi')) == r'\pi'
assert latex(Symbol('rho')) == r'\rho'
assert latex(Symbol('sigma')) == r'\sigma'
assert latex(Symbol('tau')) == r'\tau'
assert latex(Symbol('upsilon')) == r'\upsilon'
assert latex(Symbol('phi')) == r'\phi'
assert latex(Symbol('chi')) == r'\chi'
assert latex(Symbol('psi')) == r'\psi'
assert latex(Symbol('omega')) == r'\omega'
assert latex(Symbol('Alpha')) == r'A'
assert latex(Symbol('Beta')) == r'B'
assert latex(Symbol('Gamma')) == r'\Gamma'
assert latex(Symbol('Delta')) == r'\Delta'
assert latex(Symbol('Epsilon')) == r'E'
assert latex(Symbol('Zeta')) == r'Z'
assert latex(Symbol('Eta')) == r'H'
assert latex(Symbol('Theta')) == r'\Theta'
assert latex(Symbol('Iota')) == r'I'
assert latex(Symbol('Kappa')) == r'K'
assert latex(Symbol('Lambda')) == r'\Lambda'
assert latex(Symbol('Mu')) == r'M'
assert latex(Symbol('Nu')) == r'N'
assert latex(Symbol('Xi')) == r'\Xi'
assert latex(Symbol('Omicron')) == r'O'
assert latex(Symbol('Pi')) == r'\Pi'
assert latex(Symbol('Rho')) == r'P'
assert latex(Symbol('Sigma')) == r'\Sigma'
assert latex(Symbol('Tau')) == r'T'
assert latex(Symbol('Upsilon')) == r'\Upsilon'
assert latex(Symbol('Phi')) == r'\Phi'
assert latex(Symbol('Chi')) == r'X'
assert latex(Symbol('Psi')) == r'\Psi'
assert latex(Symbol('Omega')) == r'\Omega'
assert latex(Symbol('varepsilon')) == r'\varepsilon'
assert latex(Symbol('varkappa')) == r'\varkappa'
assert latex(Symbol('varphi')) == r'\varphi'
assert latex(Symbol('varpi')) == r'\varpi'
assert latex(Symbol('varrho')) == r'\varrho'
assert latex(Symbol('varsigma')) == r'\varsigma'
assert latex(Symbol('vartheta')) == r'\vartheta'
@XFAIL
def test_builtin_without_args_mismatched_names():
assert latex(CosineTransform) == r'\mathcal{COS}'
def test_builtin_no_args():
assert latex(Chi) == r'\operatorname{Chi}'
assert latex(beta) == r'\operatorname{B}'
assert latex(gamma) == r'\Gamma'
assert latex(KroneckerDelta) == r'\delta'
assert latex(DiracDelta) == r'\delta'
assert latex(lowergamma) == r'\gamma'
def test_issue_6853():
p = Function('Pi')
assert latex(p(x)) == r"\Pi{\left(x \right)}"
def test_Mul():
e = Mul(-2, x + 1, evaluate=False)
assert latex(e) == r'- 2 \left(x + 1\right)'
e = Mul(2, x + 1, evaluate=False)
assert latex(e) == r'2 \left(x + 1\right)'
e = Mul(S.One/2, x + 1, evaluate=False)
assert latex(e) == r'\frac{x + 1}{2}'
e = Mul(y, x + 1, evaluate=False)
assert latex(e) == r'y \left(x + 1\right)'
e = Mul(-y, x + 1, evaluate=False)
assert latex(e) == r'- y \left(x + 1\right)'
e = Mul(-2, x + 1)
assert latex(e) == r'- 2 x - 2'
e = Mul(2, x + 1)
assert latex(e) == r'2 x + 2'
def test_Pow():
e = Pow(2, 2, evaluate=False)
assert latex(e) == r'2^{2}'
def test_issue_7180():
assert latex(Equivalent(x, y)) == r"x \Leftrightarrow y"
assert latex(Not(Equivalent(x, y))) == r"x \not\Leftrightarrow y"
def test_issue_8409():
assert latex(S.Half**n) == r"\left(\frac{1}{2}\right)^{n}"
def test_issue_8470():
from sympy.parsing.sympy_parser import parse_expr
e = parse_expr("-B*A", evaluate=False)
assert latex(e) == r"A \left(- B\right)"
def test_issue_7117():
# See also issue #5031 (hence the evaluate=False in these).
e = Eq(x + 1, 2*x)
q = Mul(2, e, evaluate=False)
assert latex(q) == r"2 \left(x + 1 = 2 x\right)"
q = Add(6, e, evaluate=False)
assert latex(q) == r"6 + \left(x + 1 = 2 x\right)"
q = Pow(e, 2, evaluate=False)
assert latex(q) == r"\left(x + 1 = 2 x\right)^{2}"
def test_issue_15439():
x = MatrixSymbol('x', 2, 2)
y = MatrixSymbol('y', 2, 2)
assert latex((x * y).subs(y, -y)) == r"x \left(- y\right)"
assert latex((x * y).subs(y, -2*y)) == r"x \left(- 2 y\right)"
assert latex((x * y).subs(x, -x)) == r"- x y"
def test_issue_2934():
assert latex(Symbol(r'\frac{a_1}{b_1}')) == '\\frac{a_1}{b_1}'
def test_issue_10489():
latexSymbolWithBrace = 'C_{x_{0}}'
s = Symbol(latexSymbolWithBrace)
assert latex(s) == latexSymbolWithBrace
assert latex(cos(s)) == r'\cos{\left(C_{x_{0}} \right)}'
def test_issue_12886():
m__1, l__1 = symbols('m__1, l__1')
assert latex(m__1**2 + l__1**2) == r'\left(l^{1}\right)^{2} + \left(m^{1}\right)^{2}'
def test_issue_13559():
from sympy.parsing.sympy_parser import parse_expr
expr = parse_expr('5/1', evaluate=False)
assert latex(expr) == r"\frac{5}{1}"
def test_issue_13651():
expr = c + Mul(-1, a + b, evaluate=False)
assert latex(expr) == r"c - \left(a + b\right)"
def test_latex_UnevaluatedExpr():
x = symbols("x")
he = UnevaluatedExpr(1/x)
assert latex(he) == latex(1/x) == r"\frac{1}{x}"
assert latex(he**2) == r"\left(\frac{1}{x}\right)^{2}"
assert latex(he + 1) == r"1 + \frac{1}{x}"
assert latex(x*he) == r"x \frac{1}{x}"
def test_MatrixElement_printing():
# test cases for issue #11821
A = MatrixSymbol("A", 1, 3)
B = MatrixSymbol("B", 1, 3)
C = MatrixSymbol("C", 1, 3)
assert latex(A[0, 0]) == r"A_{0, 0}"
assert latex(3 * A[0, 0]) == r"3 A_{0, 0}"
F = C[0, 0].subs(C, A - B)
assert latex(F) == r"\left(A - B\right)_{0, 0}"
i, j, k = symbols("i j k")
M = MatrixSymbol("M", k, k)
N = MatrixSymbol("N", k, k)
assert latex((M*N)[i, j]) == r'\sum_{i_{1}=0}^{k - 1} M_{i, i_{1}} N_{i_{1}, j}'
def test_MatrixSymbol_printing():
# test cases for issue #14237
A = MatrixSymbol("A", 3, 3)
B = MatrixSymbol("B", 3, 3)
C = MatrixSymbol("C", 3, 3)
assert latex(-A) == r"- A"
assert latex(A - A*B - B) == r"A - A B - B"
assert latex(-A*B - A*B*C - B) == r"- A B - A B C - B"
def test_Quaternion_latex_printing():
q = Quaternion(x, y, z, t)
assert latex(q) == "x + y i + z j + t k"
q = Quaternion(x,y,z,x*t)
assert latex(q) == "x + y i + z j + t x k"
q = Quaternion(x,y,z,x+t)
assert latex(q) == r"x + y i + z j + \left(t + x\right) k"
def test_TensorProduct_printing():
from sympy.tensor.functions import TensorProduct
A = MatrixSymbol("A", 3, 3)
B = MatrixSymbol("B", 3, 3)
assert latex(TensorProduct(A, B)) == r"A \otimes B"
def test_WedgeProduct_printing():
from sympy.diffgeom.rn import R2
from sympy.diffgeom import WedgeProduct
wp = WedgeProduct(R2.dx, R2.dy)
assert latex(wp) == r"\mathrm{d}x \wedge \mathrm{d}y"
def test_issue_14041():
import sympy.physics.mechanics as me
A_frame = me.ReferenceFrame('A')
thetad, phid = me.dynamicsymbols('theta, phi', 1)
L = Symbol('L')
assert latex(L*(phid + thetad)**2*A_frame.x) == \
r"L \left(\dot{\phi} + \dot{\theta}\right)^{2}\mathbf{\hat{a}_x}"
assert latex((phid + thetad)**2*A_frame.x) == \
r"\left(\dot{\phi} + \dot{\theta}\right)^{2}\mathbf{\hat{a}_x}"
assert latex((phid*thetad)**a*A_frame.x) == \
r"\left(\dot{\phi} \dot{\theta}\right)^{a}\mathbf{\hat{a}_x}"
def test_issue_9216():
expr_1 = Pow(1, -1, evaluate=False)
assert latex(expr_1) == r"1^{-1}"
expr_2 = Pow(1, Pow(1, -1, evaluate=False), evaluate=False)
assert latex(expr_2) == r"1^{1^{-1}}"
expr_3 = Pow(3, -2, evaluate=False)
assert latex(expr_3) == r"\frac{1}{9}"
expr_4 = Pow(1, -2, evaluate=False)
assert latex(expr_4) == r"1^{-2}"
def test_latex_printer_tensor():
from sympy.tensor.tensor import TensorIndexType, tensor_indices, tensorhead
L = TensorIndexType("L")
i, j, k, l = tensor_indices("i j k l", L)
i0 = tensor_indices("i_0", L)
A, B, C, D = tensorhead("A B C D", [L], [[1]])
H = tensorhead("H", [L, L], [[1], [1]])
K = tensorhead("K", [L, L, L, L], [[1], [1], [1], [1]])
assert latex(i) == "{}^{i}"
assert latex(-i) == "{}_{i}"
expr = A(i)
assert latex(expr) == "A{}^{i}"
expr = A(i0)
assert latex(expr) == "A{}^{i_{0}}"
expr = A(-i)
assert latex(expr) == "A{}_{i}"
expr = -3*A(i)
assert latex(expr) == r"-3A{}^{i}"
expr = K(i, j, -k, -i0)
assert latex(expr) == "K{}^{ij}{}_{ki_{0}}"
expr = K(i, -j, -k, i0)
assert latex(expr) == "K{}^{i}{}_{jk}{}^{i_{0}}"
expr = K(i, -j, k, -i0)
assert latex(expr) == "K{}^{i}{}_{j}{}^{k}{}_{i_{0}}"
expr = H(i, -j)
assert latex(expr) == "H{}^{i}{}_{j}"
expr = H(i, j)
assert latex(expr) == "H{}^{ij}"
expr = H(-i, -j)
assert latex(expr) == "H{}_{ij}"
expr = (1+x)*A(i)
assert latex(expr) == r"\left(x + 1\right)A{}^{i}"
expr = H(i, -i)
assert latex(expr) == "H{}^{L_{0}}{}_{L_{0}}"
expr = H(i, -j)*A(j)*B(k)
assert latex(expr) == "H{}^{i}{}_{L_{0}}A{}^{L_{0}}B{}^{k}"
expr = A(i) + 3*B(i)
assert latex(expr) == "3B{}^{i} + A{}^{i}"
## Test ``TensorElement``:
from sympy.tensor.tensor import TensorElement
expr = TensorElement(K(i,j,k,l), {i:3, k:2})
assert latex(expr) == 'K{}^{i=3,j,k=2,l}'
expr = TensorElement(K(i,j,k,l), {i:3})
assert latex(expr) == 'K{}^{i=3,jkl}'
expr = TensorElement(K(i,-j,k,l), {i:3, k:2})
assert latex(expr) == 'K{}^{i=3}{}_{j}{}^{k=2,l}'
expr = TensorElement(K(i,-j,k,-l), {i:3, k:2})
assert latex(expr) == 'K{}^{i=3}{}_{j}{}^{k=2}{}_{l}'
expr = TensorElement(K(i,j,-k,-l), {i:3, -k:2})
assert latex(expr) == 'K{}^{i=3,j}{}_{k=2,l}'
expr = TensorElement(K(i,j,-k,-l), {i:3})
assert latex(expr) == 'K{}^{i=3,j}{}_{kl}'
def test_trace():
# Issue 15303
from sympy import trace
A = MatrixSymbol("A", 2, 2)
assert latex(trace(A)) == r"\mathrm{tr}\left(A \right)"
assert latex(trace(A**2)) == r"\mathrm{tr}\left(A^{2} \right)"
def test_print_basic():
# Issue 15303
from sympy import Basic, Expr
# dummy class for testing printing where the function is not implemented in latex.py
class UnimplementedExpr(Expr):
def __new__(cls, e):
return Basic.__new__(cls, e)
# dummy function for testing
def unimplemented_expr(expr):
return UnimplementedExpr(expr).doit()
# override class name to use superscript / subscript
def unimplemented_expr_sup_sub(expr):
result = UnimplementedExpr(expr)
result.__class__.__name__ = 'UnimplementedExpr_x^1'
return result
assert latex(unimplemented_expr(x)) == r'UnimplementedExpr\left(x\right)'
assert latex(unimplemented_expr(x**2)) == r'UnimplementedExpr\left(x^{2}\right)'
assert latex(unimplemented_expr_sup_sub(x)) == r'UnimplementedExpr^{1}_{x}\left(x\right)'
|
741734c51971bd192a4bf879492803d8f4a3a93b95cb357cb2a0577cdc6039b5
|
from sympy import TableForm, S
from sympy.printing.latex import latex
from sympy.abc import x
from sympy.functions.elementary.miscellaneous import sqrt
from sympy.functions.elementary.trigonometric import sin
from sympy.utilities.pytest import raises
from textwrap import dedent
def test_TableForm():
s = str(TableForm([["a", "b"], ["c", "d"], ["e", 0]],
headings="automatic"))
assert s == (
' | 1 2\n'
'-------\n'
'1 | a b\n'
'2 | c d\n'
'3 | e '
)
s = str(TableForm([["a", "b"], ["c", "d"], ["e", 0]],
headings="automatic", wipe_zeros=False))
assert s == dedent('''\
| 1 2
-------
1 | a b
2 | c d
3 | e 0''')
s = str(TableForm([[x**2, "b"], ["c", x**2], ["e", "f"]],
headings=("automatic", None)))
assert s == (
'1 | x**2 b \n'
'2 | c x**2\n'
'3 | e f '
)
s = str(TableForm([["a", "b"], ["c", "d"], ["e", "f"]],
headings=(None, "automatic")))
assert s == dedent('''\
1 2
---
a b
c d
e f''')
s = str(TableForm([[5, 7], [4, 2], [10, 3]],
headings=[["Group A", "Group B", "Group C"], ["y1", "y2"]]))
assert s == (
' | y1 y2\n'
'---------------\n'
'Group A | 5 7 \n'
'Group B | 4 2 \n'
'Group C | 10 3 '
)
raises(
ValueError,
lambda:
TableForm(
[[5, 7], [4, 2], [10, 3]],
headings=[["Group A", "Group B", "Group C"], ["y1", "y2"]],
alignments="middle")
)
s = str(TableForm([[5, 7], [4, 2], [10, 3]],
headings=[["Group A", "Group B", "Group C"], ["y1", "y2"]],
alignments="right"))
assert s == dedent('''\
| y1 y2
---------------
Group A | 5 7
Group B | 4 2
Group C | 10 3''')
# other alignment permutations
d = [[1, 100], [100, 1]]
s = TableForm(d, headings=(('xxx', 'x'), None), alignments='l')
assert str(s) == (
'xxx | 1 100\n'
' x | 100 1 '
)
s = TableForm(d, headings=(('xxx', 'x'), None), alignments='lr')
assert str(s) == dedent('''\
xxx | 1 100
x | 100 1''')
s = TableForm(d, headings=(('xxx', 'x'), None), alignments='clr')
assert str(s) == dedent('''\
xxx | 1 100
x | 100 1''')
s = TableForm(d, headings=(('xxx', 'x'), None))
assert str(s) == (
'xxx | 1 100\n'
' x | 100 1 '
)
raises(ValueError, lambda: TableForm(d, alignments='clr'))
#pad
s = str(TableForm([[None, "-", 2], [1]], pad='?'))
assert s == dedent('''\
? - 2
1 ? ?''')
def test_TableForm_latex():
s = latex(TableForm([[0, x**3], ["c", S(1)/4], [sqrt(x), sin(x**2)]],
wipe_zeros=True, headings=("automatic", "automatic")))
assert s == (
'\\begin{tabular}{r l l}\n'
' & 1 & 2 \\\\\n'
'\\hline\n'
'1 & & $x^{3}$ \\\\\n'
'2 & $c$ & $\\frac{1}{4}$ \\\\\n'
'3 & $\\sqrt{x}$ & $\\sin{\\left(x^{2} \\right)}$ \\\\\n'
'\\end{tabular}'
)
s = latex(TableForm([[0, x**3], ["c", S(1)/4], [sqrt(x), sin(x**2)]],
wipe_zeros=True, headings=("automatic", "automatic"), alignments='l'))
assert s == (
'\\begin{tabular}{r l l}\n'
' & 1 & 2 \\\\\n'
'\\hline\n'
'1 & & $x^{3}$ \\\\\n'
'2 & $c$ & $\\frac{1}{4}$ \\\\\n'
'3 & $\\sqrt{x}$ & $\\sin{\\left(x^{2} \\right)}$ \\\\\n'
'\\end{tabular}'
)
s = latex(TableForm([[0, x**3], ["c", S(1)/4], [sqrt(x), sin(x**2)]],
wipe_zeros=True, headings=("automatic", "automatic"), alignments='l'*3))
assert s == (
'\\begin{tabular}{l l l}\n'
' & 1 & 2 \\\\\n'
'\\hline\n'
'1 & & $x^{3}$ \\\\\n'
'2 & $c$ & $\\frac{1}{4}$ \\\\\n'
'3 & $\\sqrt{x}$ & $\\sin{\\left(x^{2} \\right)}$ \\\\\n'
'\\end{tabular}'
)
s = latex(TableForm([["a", x**3], ["c", S(1)/4], [sqrt(x), sin(x**2)]],
headings=("automatic", "automatic")))
assert s == (
'\\begin{tabular}{r l l}\n'
' & 1 & 2 \\\\\n'
'\\hline\n'
'1 & $a$ & $x^{3}$ \\\\\n'
'2 & $c$ & $\\frac{1}{4}$ \\\\\n'
'3 & $\\sqrt{x}$ & $\\sin{\\left(x^{2} \\right)}$ \\\\\n'
'\\end{tabular}'
)
s = latex(TableForm([["a", x**3], ["c", S(1)/4], [sqrt(x), sin(x**2)]],
formats=['(%s)', None], headings=("automatic", "automatic")))
assert s == (
'\\begin{tabular}{r l l}\n'
' & 1 & 2 \\\\\n'
'\\hline\n'
'1 & (a) & $x^{3}$ \\\\\n'
'2 & (c) & $\\frac{1}{4}$ \\\\\n'
'3 & (sqrt(x)) & $\\sin{\\left(x^{2} \\right)}$ \\\\\n'
'\\end{tabular}'
)
def neg_in_paren(x, i, j):
if i % 2:
return ('(%s)' if x < 0 else '%s') % x
else:
pass # use default print
s = latex(TableForm([[-1, 2], [-3, 4]],
formats=[neg_in_paren]*2, headings=("automatic", "automatic")))
assert s == (
'\\begin{tabular}{r l l}\n'
' & 1 & 2 \\\\\n'
'\\hline\n'
'1 & -1 & 2 \\\\\n'
'2 & (-3) & 4 \\\\\n'
'\\end{tabular}'
)
s = latex(TableForm([["a", x**3], ["c", S(1)/4], [sqrt(x), sin(x**2)]]))
assert s == (
'\\begin{tabular}{l l}\n'
'$a$ & $x^{3}$ \\\\\n'
'$c$ & $\\frac{1}{4}$ \\\\\n'
'$\\sqrt{x}$ & $\\sin{\\left(x^{2} \\right)}$ \\\\\n'
'\\end{tabular}'
)
|
84856d24d2c913e99bb9ae8bc6740ba0da7ebb3d412331c3b48ed960ddf37f73
|
from sympy.core import (S, pi, oo, symbols, Function,
Rational, Integer, Tuple, Derivative)
from sympy.integrals import Integral
from sympy.concrete import Sum
from sympy.functions import exp, sin, cos, conjugate, Max, Min
from sympy import mathematica_code as mcode
x, y, z = symbols('x,y,z')
f = Function('f')
def test_Integer():
assert mcode(Integer(67)) == "67"
assert mcode(Integer(-1)) == "-1"
def test_Rational():
assert mcode(Rational(3, 7)) == "3/7"
assert mcode(Rational(18, 9)) == "2"
assert mcode(Rational(3, -7)) == "-3/7"
assert mcode(Rational(-3, -7)) == "3/7"
assert mcode(x + Rational(3, 7)) == "x + 3/7"
assert mcode(Rational(3, 7)*x) == "(3/7)*x"
def test_Function():
assert mcode(f(x, y, z)) == "f[x, y, z]"
assert mcode(sin(x) ** cos(x)) == "Sin[x]^Cos[x]"
assert mcode(conjugate(x)) == "Conjugate[x]"
assert mcode(Max(x,y,z)*Min(y,z)) == "Max[x, y, z]*Min[y, z]"
def test_Pow():
assert mcode(x**3) == "x^3"
assert mcode(x**(y**3)) == "x^(y^3)"
assert mcode(1/(f(x)*3.5)**(x - y**x)/(x**2 + y)) == \
"(3.5*f[x])^(-x + y^x)/(x^2 + y)"
assert mcode(x**-1.0) == 'x^(-1.0)'
assert mcode(x**Rational(2, 3)) == 'x^(2/3)'
def test_Mul():
A, B, C, D = symbols('A B C D', commutative=False)
assert mcode(x*y*z) == "x*y*z"
assert mcode(x*y*A) == "x*y*A"
assert mcode(x*y*A*B) == "x*y*A**B"
assert mcode(x*y*A*B*C) == "x*y*A**B**C"
assert mcode(x*A*B*(C + D)*A*y) == "x*y*A**B**(C + D)**A"
def test_constants():
assert mcode(pi) == "Pi"
assert mcode(oo) == "Infinity"
assert mcode(S.NegativeInfinity) == "-Infinity"
assert mcode(S.EulerGamma) == "EulerGamma"
assert mcode(S.Catalan) == "Catalan"
assert mcode(S.Exp1) == "E"
def test_containers():
assert mcode([1, 2, 3, [4, 5, [6, 7]], 8, [9, 10], 11]) == \
"{1, 2, 3, {4, 5, {6, 7}}, 8, {9, 10}, 11}"
assert mcode((1, 2, (3, 4))) == "{1, 2, {3, 4}}"
assert mcode([1]) == "{1}"
assert mcode((1,)) == "{1}"
assert mcode(Tuple(*[1, 2, 3])) == "{1, 2, 3}"
def test_matrices():
from sympy.matrices import MutableDenseMatrix, MutableSparseMatrix
A = MutableDenseMatrix(
[[1, -1, 0, 0],
[0, 1, -1, 0],
[0, 0, 1, -1],
[0, 0, 0, 1]]
)
B = MutableSparseMatrix(
[[1, -1, 0, 0],
[0, 1, -1, 0],
[0, 0, 1, -1],
[0, 0, 0, 1]]
)
assert mcode(A) == """\
{{1, -1, 0, 0}, \
{0, 1, -1, 0}, \
{0, 0, 1, -1}, \
{0, 0, 0, 1}}\
"""
assert mcode(B) == """\
SparseArray[\
{{1, 1} -> 1, {1, 2} -> -1, {2, 2} -> 1, {2, 3} -> -1, \
{3, 3} -> 1, {3, 4} -> -1, {4, 4} -> 1}, {4, 4}]\
"""
# Trivial cases of matrices
assert mcode(MutableDenseMatrix(0, 0, [])) == '{}'
assert mcode(MutableSparseMatrix(0, 0, [])) == 'SparseArray[{}, {0, 0}]'
assert mcode(MutableDenseMatrix(0, 3, [])) == '{}'
assert mcode(MutableSparseMatrix(0, 3, [])) == 'SparseArray[{}, {0, 3}]'
assert mcode(MutableDenseMatrix(3, 0, [])) == '{{}, {}, {}}'
assert mcode(MutableSparseMatrix(3, 0, [])) == 'SparseArray[{}, {3, 0}]'
def test_Integral():
assert mcode(Integral(sin(sin(x)), x)) == "Hold[Integrate[Sin[Sin[x]], x]]"
assert mcode(Integral(exp(-x**2 - y**2),
(x, -oo, oo),
(y, -oo, oo))) == \
"Hold[Integrate[Exp[-x^2 - y^2], {x, -Infinity, Infinity}, " \
"{y, -Infinity, Infinity}]]"
def test_Derivative():
assert mcode(Derivative(sin(x), x)) == "Hold[D[Sin[x], x]]"
assert mcode(Derivative(x, x)) == "Hold[D[x, x]]"
assert mcode(Derivative(sin(x)*y**4, x, 2)) == "Hold[D[y^4*Sin[x], {x, 2}]]"
assert mcode(Derivative(sin(x)*y**4, x, y, x)) == "Hold[D[y^4*Sin[x], x, y, x]]"
assert mcode(Derivative(sin(x)*y**4, x, y, 3, x)) == "Hold[D[y^4*Sin[x], x, {y, 3}, x]]"
def test_Sum():
assert mcode(Sum(sin(x), (x, 0, 10))) == "Hold[Sum[Sin[x], {x, 0, 10}]]"
assert mcode(Sum(exp(-x**2 - y**2),
(x, -oo, oo),
(y, -oo, oo))) == \
"Hold[Sum[Exp[-x^2 - y^2], {x, -Infinity, Infinity}, " \
"{y, -Infinity, Infinity}]]"
|
c7542270981fd4ed5f07286a94f038d41a87acb92a5a36400230878d92f13811
|
from sympy.printing.codeprinter import CodePrinter
from sympy.printing.str import StrPrinter
from sympy.core import symbols
from sympy.core.symbol import Dummy
from sympy.utilities.pytest import raises
def setup_test_printer(**kwargs):
p = CodePrinter(settings=kwargs)
p._not_supported = set()
p._number_symbols = set()
return p
def test_print_Dummy():
d = Dummy('d')
p = setup_test_printer()
assert p._print_Dummy(d) == "d_%i" % d.dummy_index
def test_print_Symbol():
x, y = symbols('x, if')
p = setup_test_printer()
assert p._print(x) == 'x'
assert p._print(y) == 'if'
p.reserved_words.update(['if'])
assert p._print(y) == 'if_'
p = setup_test_printer(error_on_reserved=True)
p.reserved_words.update(['if'])
with raises(ValueError):
p._print(y)
p = setup_test_printer(reserved_word_suffix='_He_Man')
p.reserved_words.update(['if'])
assert p._print(y) == 'if_He_Man'
def test_issue_15791():
assert (CodePrinter._print_MutableSparseMatrix.__name__ ==
CodePrinter._print_not_supported.__name__)
assert (CodePrinter._print_ImmutableSparseMatrix.__name__ ==
CodePrinter._print_not_supported.__name__)
assert (CodePrinter._print_MutableSparseMatrix.__name__ !=
StrPrinter._print_MatrixBase.__name__)
assert (CodePrinter._print_ImmutableSparseMatrix.__name__ !=
StrPrinter._print_MatrixBase.__name__)
|
1db61e304756d2a29c3579070d19121f40ce4ccccba2b93fb26e7b24ccc9ecc7
|
from sympy import (Piecewise, lambdify, Equality, Unequality, Sum, Mod, cbrt,
sqrt, MatrixSymbol)
from sympy import eye
from sympy.abc import x, i, j, a, b, c, d
from sympy.codegen.cfunctions import log1p, expm1, hypot, log10, exp2, log2, Cbrt, Sqrt
from sympy.codegen.array_utils import (CodegenArrayContraction,
CodegenArrayTensorProduct, CodegenArrayDiagonal,
CodegenArrayPermuteDims, CodegenArrayElementwiseAdd)
from sympy.printing.lambdarepr import NumPyPrinter
from sympy.utilities.pytest import warns_deprecated_sympy
from sympy.utilities.pytest import skip
from sympy.external import import_module
np = import_module('numpy')
def test_numpy_piecewise_regression():
"""
NumPyPrinter needs to print Piecewise()'s choicelist as a list to avoid
breaking compatibility with numpy 1.8. This is not necessary in numpy 1.9+.
See gh-9747 and gh-9749 for details.
"""
p = Piecewise((1, x < 0), (0, True))
assert NumPyPrinter().doprint(p) == 'numpy.select([numpy.less(x, 0),True], [1,0], default=numpy.nan)'
def test_sum():
if not np:
skip("NumPy not installed")
s = Sum(x ** i, (i, a, b))
f = lambdify((a, b, x), s, 'numpy')
a_, b_ = 0, 10
x_ = np.linspace(-1, +1, 10)
assert np.allclose(f(a_, b_, x_), sum(x_ ** i_ for i_ in range(a_, b_ + 1)))
s = Sum(i * x, (i, a, b))
f = lambdify((a, b, x), s, 'numpy')
a_, b_ = 0, 10
x_ = np.linspace(-1, +1, 10)
assert np.allclose(f(a_, b_, x_), sum(i_ * x_ for i_ in range(a_, b_ + 1)))
def test_multiple_sums():
if not np:
skip("NumPy not installed")
s = Sum((x + j) * i, (i, a, b), (j, c, d))
f = lambdify((a, b, c, d, x), s, 'numpy')
a_, b_ = 0, 10
c_, d_ = 11, 21
x_ = np.linspace(-1, +1, 10)
assert np.allclose(f(a_, b_, c_, d_, x_),
sum((x_ + j_) * i_ for i_ in range(a_, b_ + 1) for j_ in range(c_, d_ + 1)))
def test_codegen_einsum():
if not np:
skip("NumPy not installed")
M = MatrixSymbol("M", 2, 2)
N = MatrixSymbol("N", 2, 2)
cg = CodegenArrayContraction.from_MatMul(M*N)
f = lambdify((M, N), cg, 'numpy')
ma = np.matrix([[1, 2], [3, 4]])
mb = np.matrix([[1,-2], [-1, 3]])
assert (f(ma, mb) == ma*mb).all()
def test_codegen_extra():
if not np:
skip("NumPy not installed")
M = MatrixSymbol("M", 2, 2)
N = MatrixSymbol("N", 2, 2)
P = MatrixSymbol("P", 2, 2)
Q = MatrixSymbol("Q", 2, 2)
ma = np.matrix([[1, 2], [3, 4]])
mb = np.matrix([[1,-2], [-1, 3]])
mc = np.matrix([[2, 0], [1, 2]])
md = np.matrix([[1,-1], [4, 7]])
cg = CodegenArrayTensorProduct(M, N)
f = lambdify((M, N), cg, 'numpy')
assert (f(ma, mb) == np.einsum(ma, [0, 1], mb, [2, 3])).all()
cg = CodegenArrayElementwiseAdd(M, N)
f = lambdify((M, N), cg, 'numpy')
assert (f(ma, mb) == ma+mb).all()
cg = CodegenArrayElementwiseAdd(M, N, P)
f = lambdify((M, N, P), cg, 'numpy')
assert (f(ma, mb, mc) == ma+mb+mc).all()
cg = CodegenArrayElementwiseAdd(M, N, P, Q)
f = lambdify((M, N, P, Q), cg, 'numpy')
assert (f(ma, mb, mc, md) == ma+mb+mc+md).all()
cg = CodegenArrayPermuteDims(M, [1, 0])
f = lambdify((M,), cg, 'numpy')
assert (f(ma) == ma.T).all()
cg = CodegenArrayPermuteDims(CodegenArrayTensorProduct(M, N), [1, 2, 3, 0])
f = lambdify((M, N), cg, 'numpy')
assert (f(ma, mb) == np.transpose(np.einsum(ma, [0, 1], mb, [2, 3]), (1, 2, 3, 0))).all()
cg = CodegenArrayDiagonal(CodegenArrayTensorProduct(M, N), (1, 2))
f = lambdify((M, N), cg, 'numpy')
assert (f(ma, mb) == np.diagonal(np.einsum(ma, [0, 1], mb, [2, 3]), axis1=1, axis2=2)).all()
def test_relational():
if not np:
skip("NumPy not installed")
e = Equality(x, 1)
f = lambdify((x,), e)
x_ = np.array([0, 1, 2])
assert np.array_equal(f(x_), [False, True, False])
e = Unequality(x, 1)
f = lambdify((x,), e)
x_ = np.array([0, 1, 2])
assert np.array_equal(f(x_), [True, False, True])
e = (x < 1)
f = lambdify((x,), e)
x_ = np.array([0, 1, 2])
assert np.array_equal(f(x_), [True, False, False])
e = (x <= 1)
f = lambdify((x,), e)
x_ = np.array([0, 1, 2])
assert np.array_equal(f(x_), [True, True, False])
e = (x > 1)
f = lambdify((x,), e)
x_ = np.array([0, 1, 2])
assert np.array_equal(f(x_), [False, False, True])
e = (x >= 1)
f = lambdify((x,), e)
x_ = np.array([0, 1, 2])
assert np.array_equal(f(x_), [False, True, True])
def test_mod():
if not np:
skip("NumPy not installed")
e = Mod(a, b)
f = lambdify((a, b), e)
a_ = np.array([0, 1, 2, 3])
b_ = 2
assert np.array_equal(f(a_, b_), [0, 1, 0, 1])
a_ = np.array([0, 1, 2, 3])
b_ = np.array([2, 2, 2, 2])
assert np.array_equal(f(a_, b_), [0, 1, 0, 1])
a_ = np.array([2, 3, 4, 5])
b_ = np.array([2, 3, 4, 5])
assert np.array_equal(f(a_, b_), [0, 0, 0, 0])
def test_expm1():
if not np:
skip("NumPy not installed")
f = lambdify((a,), expm1(a), 'numpy')
assert abs(f(1e-10) - 1e-10 - 5e-21) < 1e-22
def test_log1p():
if not np:
skip("NumPy not installed")
f = lambdify((a,), log1p(a), 'numpy')
assert abs(f(1e-99) - 1e-99) < 1e-100
def test_hypot():
if not np:
skip("NumPy not installed")
assert abs(lambdify((a, b), hypot(a, b), 'numpy')(3, 4) - 5) < 1e-16
def test_log10():
if not np:
skip("NumPy not installed")
assert abs(lambdify((a,), log10(a), 'numpy')(100) - 2) < 1e-16
def test_exp2():
if not np:
skip("NumPy not installed")
assert abs(lambdify((a,), exp2(a), 'numpy')(5) - 32) < 1e-16
def test_log2():
if not np:
skip("NumPy not installed")
assert abs(lambdify((a,), log2(a), 'numpy')(256) - 8) < 1e-16
def test_Sqrt():
if not np:
skip("NumPy not installed")
assert abs(lambdify((a,), Sqrt(a), 'numpy')(4) - 2) < 1e-16
def test_sqrt():
if not np:
skip("NumPy not installed")
assert abs(lambdify((a,), sqrt(a), 'numpy')(4) - 2) < 1e-16
def test_issue_15601():
if not np:
skip("Numpy not installed")
M = MatrixSymbol("M", 3, 3)
N = MatrixSymbol("N", 3, 3)
expr = M*N
f = lambdify((M, N), expr, "numpy")
with warns_deprecated_sympy():
ans = f(eye(3), eye(3))
assert np.array_equal(ans, np.array([1, 0, 0, 0, 1, 0, 0, 0, 1]))
|
237308bfb05879f77c21165f4bbf1a126798f42ad32278cfc13b0ff42aaf38f8
|
from sympy import (Add, Basic, Expr, S, Symbol, Wild, Float, Integer, Rational, I,
sin, cos, tan, exp, log, nan, oo, sqrt, symbols, Integral, sympify,
WildFunction, Poly, Function, Derivative, Number, pi, NumberSymbol, zoo,
Piecewise, Mul, Pow, nsimplify, ratsimp, trigsimp, radsimp, powsimp,
simplify, together, collect, factorial, apart, combsimp, factor, refine,
cancel, Tuple, default_sort_key, DiracDelta, gamma, Dummy, Sum, E,
exp_polar, expand, diff, O, Heaviside, Si, Max, UnevaluatedExpr,
integrate, gammasimp)
from sympy.core.function import AppliedUndef
from sympy.core.compatibility import range
from sympy.physics.secondquant import FockState
from sympy.physics.units import meter
from sympy.utilities.pytest import raises, XFAIL
from sympy.abc import a, b, c, n, t, u, x, y, z
class DummyNumber(object):
"""
Minimal implementation of a number that works with SymPy.
If one has a Number class (e.g. Sage Integer, or some other custom class)
that one wants to work well with SymPy, one has to implement at least the
methods of this class DummyNumber, resp. its subclasses I5 and F1_1.
Basically, one just needs to implement either __int__() or __float__() and
then one needs to make sure that the class works with Python integers and
with itself.
"""
def __radd__(self, a):
if isinstance(a, (int, float)):
return a + self.number
return NotImplemented
def __truediv__(a, b):
return a.__div__(b)
def __rtruediv__(a, b):
return a.__rdiv__(b)
def __add__(self, a):
if isinstance(a, (int, float, DummyNumber)):
return self.number + a
return NotImplemented
def __rsub__(self, a):
if isinstance(a, (int, float)):
return a - self.number
return NotImplemented
def __sub__(self, a):
if isinstance(a, (int, float, DummyNumber)):
return self.number - a
return NotImplemented
def __rmul__(self, a):
if isinstance(a, (int, float)):
return a * self.number
return NotImplemented
def __mul__(self, a):
if isinstance(a, (int, float, DummyNumber)):
return self.number * a
return NotImplemented
def __rdiv__(self, a):
if isinstance(a, (int, float)):
return a / self.number
return NotImplemented
def __div__(self, a):
if isinstance(a, (int, float, DummyNumber)):
return self.number / a
return NotImplemented
def __rpow__(self, a):
if isinstance(a, (int, float)):
return a ** self.number
return NotImplemented
def __pow__(self, a):
if isinstance(a, (int, float, DummyNumber)):
return self.number ** a
return NotImplemented
def __pos__(self):
return self.number
def __neg__(self):
return - self.number
class I5(DummyNumber):
number = 5
def __int__(self):
return self.number
class F1_1(DummyNumber):
number = 1.1
def __float__(self):
return self.number
i5 = I5()
f1_1 = F1_1()
# basic sympy objects
basic_objs = [
Rational(2),
Float("1.3"),
x,
y,
pow(x, y)*y,
]
# all supported objects
all_objs = basic_objs + [
5,
5.5,
i5,
f1_1
]
def dotest(s):
for x in all_objs:
for y in all_objs:
s(x, y)
return True
def test_basic():
def j(a, b):
x = a
x = +a
x = -a
x = a + b
x = a - b
x = a*b
x = a/b
x = a**b
assert dotest(j)
def test_ibasic():
def s(a, b):
x = a
x += b
x = a
x -= b
x = a
x *= b
x = a
x /= b
assert dotest(s)
def test_relational():
from sympy import Lt
assert (pi < 3) is S.false
assert (pi <= 3) is S.false
assert (pi > 3) is S.true
assert (pi >= 3) is S.true
assert (-pi < 3) is S.true
assert (-pi <= 3) is S.true
assert (-pi > 3) is S.false
assert (-pi >= 3) is S.false
r = Symbol('r', real=True)
assert (r - 2 < r - 3) is S.false
assert Lt(x + I, x + I + 2).func == Lt # issue 8288
def test_relational_assumptions():
from sympy import Lt, Gt, Le, Ge
m1 = Symbol("m1", nonnegative=False)
m2 = Symbol("m2", positive=False)
m3 = Symbol("m3", nonpositive=False)
m4 = Symbol("m4", negative=False)
assert (m1 < 0) == Lt(m1, 0)
assert (m2 <= 0) == Le(m2, 0)
assert (m3 > 0) == Gt(m3, 0)
assert (m4 >= 0) == Ge(m4, 0)
m1 = Symbol("m1", nonnegative=False, real=True)
m2 = Symbol("m2", positive=False, real=True)
m3 = Symbol("m3", nonpositive=False, real=True)
m4 = Symbol("m4", negative=False, real=True)
assert (m1 < 0) is S.true
assert (m2 <= 0) is S.true
assert (m3 > 0) is S.true
assert (m4 >= 0) is S.true
m1 = Symbol("m1", negative=True)
m2 = Symbol("m2", nonpositive=True)
m3 = Symbol("m3", positive=True)
m4 = Symbol("m4", nonnegative=True)
assert (m1 < 0) is S.true
assert (m2 <= 0) is S.true
assert (m3 > 0) is S.true
assert (m4 >= 0) is S.true
m1 = Symbol("m1", negative=False, real=True)
m2 = Symbol("m2", nonpositive=False, real=True)
m3 = Symbol("m3", positive=False, real=True)
m4 = Symbol("m4", nonnegative=False, real=True)
assert (m1 < 0) is S.false
assert (m2 <= 0) is S.false
assert (m3 > 0) is S.false
assert (m4 >= 0) is S.false
def test_relational_noncommutative():
from sympy import Lt, Gt, Le, Ge
A, B = symbols('A,B', commutative=False)
assert (A < B) == Lt(A, B)
assert (A <= B) == Le(A, B)
assert (A > B) == Gt(A, B)
assert (A >= B) == Ge(A, B)
def test_basic_nostr():
for obj in basic_objs:
raises(TypeError, lambda: obj + '1')
raises(TypeError, lambda: obj - '1')
if obj == 2:
assert obj * '1' == '11'
else:
raises(TypeError, lambda: obj * '1')
raises(TypeError, lambda: obj / '1')
raises(TypeError, lambda: obj ** '1')
def test_series_expansion_for_uniform_order():
assert (1/x + y + x).series(x, 0, 0) == 1/x + O(1, x)
assert (1/x + y + x).series(x, 0, 1) == 1/x + y + O(x)
assert (1/x + 1 + x).series(x, 0, 0) == 1/x + O(1, x)
assert (1/x + 1 + x).series(x, 0, 1) == 1/x + 1 + O(x)
assert (1/x + x).series(x, 0, 0) == 1/x + O(1, x)
assert (1/x + y + y*x + x).series(x, 0, 0) == 1/x + O(1, x)
assert (1/x + y + y*x + x).series(x, 0, 1) == 1/x + y + O(x)
def test_leadterm():
assert (3 + 2*x**(log(3)/log(2) - 1)).leadterm(x) == (3, 0)
assert (1/x**2 + 1 + x + x**2).leadterm(x)[1] == -2
assert (1/x + 1 + x + x**2).leadterm(x)[1] == -1
assert (x**2 + 1/x).leadterm(x)[1] == -1
assert (1 + x**2).leadterm(x)[1] == 0
assert (x + 1).leadterm(x)[1] == 0
assert (x + x**2).leadterm(x)[1] == 1
assert (x**2).leadterm(x)[1] == 2
def test_as_leading_term():
assert (3 + 2*x**(log(3)/log(2) - 1)).as_leading_term(x) == 3
assert (1/x**2 + 1 + x + x**2).as_leading_term(x) == 1/x**2
assert (1/x + 1 + x + x**2).as_leading_term(x) == 1/x
assert (x**2 + 1/x).as_leading_term(x) == 1/x
assert (1 + x**2).as_leading_term(x) == 1
assert (x + 1).as_leading_term(x) == 1
assert (x + x**2).as_leading_term(x) == x
assert (x**2).as_leading_term(x) == x**2
assert (x + oo).as_leading_term(x) == oo
raises(ValueError, lambda: (x + 1).as_leading_term(1))
def test_leadterm2():
assert (x*cos(1)*cos(1 + sin(1)) + sin(1 + sin(1))).leadterm(x) == \
(sin(1 + sin(1)), 0)
def test_leadterm3():
assert (y + z + x).leadterm(x) == (y + z, 0)
def test_as_leading_term2():
assert (x*cos(1)*cos(1 + sin(1)) + sin(1 + sin(1))).as_leading_term(x) == \
sin(1 + sin(1))
def test_as_leading_term3():
assert (2 + pi + x).as_leading_term(x) == 2 + pi
assert (2*x + pi*x + x**2).as_leading_term(x) == (2 + pi)*x
def test_as_leading_term4():
# see issue 6843
n = Symbol('n', integer=True, positive=True)
r = -n**3/(2*n**2 + 4*n + 2) - n**2/(n**2 + 2*n + 1) + \
n**2/(n + 1) - n/(2*n**2 + 4*n + 2) + n/(n*x + x) + 2*n/(n + 1) - \
1 + 1/(n*x + x) + 1/(n + 1) - 1/x
assert r.as_leading_term(x).cancel() == n/2
def test_as_leading_term_stub():
class foo(Function):
pass
assert foo(1/x).as_leading_term(x) == foo(1/x)
assert foo(1).as_leading_term(x) == foo(1)
raises(NotImplementedError, lambda: foo(x).as_leading_term(x))
def test_as_leading_term_deriv_integral():
# related to issue 11313
assert Derivative(x ** 3, x).as_leading_term(x) == 3*x**2
assert Derivative(x ** 3, y).as_leading_term(x) == 0
assert Integral(x ** 3, x).as_leading_term(x) == x**4/4
assert Integral(x ** 3, y).as_leading_term(x) == y*x**3
assert Derivative(exp(x), x).as_leading_term(x) == 1
assert Derivative(log(x), x).as_leading_term(x) == (1/x).as_leading_term(x)
def test_atoms():
assert x.atoms() == {x}
assert (1 + x).atoms() == {x, S(1)}
assert (1 + 2*cos(x)).atoms(Symbol) == {x}
assert (1 + 2*cos(x)).atoms(Symbol, Number) == {S(1), S(2), x}
assert (2*(x**(y**x))).atoms() == {S(2), x, y}
assert Rational(1, 2).atoms() == {S.Half}
assert Rational(1, 2).atoms(Symbol) == set([])
assert sin(oo).atoms(oo) == set()
assert Poly(0, x).atoms() == {S.Zero}
assert Poly(1, x).atoms() == {S.One}
assert Poly(x, x).atoms() == {x}
assert Poly(x, x, y).atoms() == {x}
assert Poly(x + y, x, y).atoms() == {x, y}
assert Poly(x + y, x, y, z).atoms() == {x, y}
assert Poly(x + y*t, x, y, z).atoms() == {t, x, y}
assert (I*pi).atoms(NumberSymbol) == {pi}
assert (I*pi).atoms(NumberSymbol, I) == \
(I*pi).atoms(I, NumberSymbol) == {pi, I}
assert exp(exp(x)).atoms(exp) == {exp(exp(x)), exp(x)}
assert (1 + x*(2 + y) + exp(3 + z)).atoms(Add) == \
{1 + x*(2 + y) + exp(3 + z), 2 + y, 3 + z}
# issue 6132
f = Function('f')
e = (f(x) + sin(x) + 2)
assert e.atoms(AppliedUndef) == \
{f(x)}
assert e.atoms(AppliedUndef, Function) == \
{f(x), sin(x)}
assert e.atoms(Function) == \
{f(x), sin(x)}
assert e.atoms(AppliedUndef, Number) == \
{f(x), S(2)}
assert e.atoms(Function, Number) == \
{S(2), sin(x), f(x)}
def test_is_polynomial():
k = Symbol('k', nonnegative=True, integer=True)
assert Rational(2).is_polynomial(x, y, z) is True
assert (S.Pi).is_polynomial(x, y, z) is True
assert x.is_polynomial(x) is True
assert x.is_polynomial(y) is True
assert (x**2).is_polynomial(x) is True
assert (x**2).is_polynomial(y) is True
assert (x**(-2)).is_polynomial(x) is False
assert (x**(-2)).is_polynomial(y) is True
assert (2**x).is_polynomial(x) is False
assert (2**x).is_polynomial(y) is True
assert (x**k).is_polynomial(x) is False
assert (x**k).is_polynomial(k) is False
assert (x**x).is_polynomial(x) is False
assert (k**k).is_polynomial(k) is False
assert (k**x).is_polynomial(k) is False
assert (x**(-k)).is_polynomial(x) is False
assert ((2*x)**k).is_polynomial(x) is False
assert (x**2 + 3*x - 8).is_polynomial(x) is True
assert (x**2 + 3*x - 8).is_polynomial(y) is True
assert (x**2 + 3*x - 8).is_polynomial() is True
assert sqrt(x).is_polynomial(x) is False
assert (sqrt(x)**3).is_polynomial(x) is False
assert (x**2 + 3*x*sqrt(y) - 8).is_polynomial(x) is True
assert (x**2 + 3*x*sqrt(y) - 8).is_polynomial(y) is False
assert ((x**2)*(y**2) + x*(y**2) + y*x + exp(2)).is_polynomial() is True
assert ((x**2)*(y**2) + x*(y**2) + y*x + exp(x)).is_polynomial() is False
assert (
(x**2)*(y**2) + x*(y**2) + y*x + exp(2)).is_polynomial(x, y) is True
assert (
(x**2)*(y**2) + x*(y**2) + y*x + exp(x)).is_polynomial(x, y) is False
def test_is_rational_function():
assert Integer(1).is_rational_function() is True
assert Integer(1).is_rational_function(x) is True
assert Rational(17, 54).is_rational_function() is True
assert Rational(17, 54).is_rational_function(x) is True
assert (12/x).is_rational_function() is True
assert (12/x).is_rational_function(x) is True
assert (x/y).is_rational_function() is True
assert (x/y).is_rational_function(x) is True
assert (x/y).is_rational_function(x, y) is True
assert (x**2 + 1/x/y).is_rational_function() is True
assert (x**2 + 1/x/y).is_rational_function(x) is True
assert (x**2 + 1/x/y).is_rational_function(x, y) is True
assert (sin(y)/x).is_rational_function() is False
assert (sin(y)/x).is_rational_function(y) is False
assert (sin(y)/x).is_rational_function(x) is True
assert (sin(y)/x).is_rational_function(x, y) is False
assert (S.NaN).is_rational_function() is False
assert (S.Infinity).is_rational_function() is False
assert (-S.Infinity).is_rational_function() is False
assert (S.ComplexInfinity).is_rational_function() is False
def test_is_algebraic_expr():
assert sqrt(3).is_algebraic_expr(x) is True
assert sqrt(3).is_algebraic_expr() is True
eq = ((1 + x**2)/(1 - y**2))**(S(1)/3)
assert eq.is_algebraic_expr(x) is True
assert eq.is_algebraic_expr(y) is True
assert (sqrt(x) + y**(S(2)/3)).is_algebraic_expr(x) is True
assert (sqrt(x) + y**(S(2)/3)).is_algebraic_expr(y) is True
assert (sqrt(x) + y**(S(2)/3)).is_algebraic_expr() is True
assert (cos(y)/sqrt(x)).is_algebraic_expr() is False
assert (cos(y)/sqrt(x)).is_algebraic_expr(x) is True
assert (cos(y)/sqrt(x)).is_algebraic_expr(y) is False
assert (cos(y)/sqrt(x)).is_algebraic_expr(x, y) is False
def test_SAGE1():
#see https://github.com/sympy/sympy/issues/3346
class MyInt:
def _sympy_(self):
return Integer(5)
m = MyInt()
e = Rational(2)*m
assert e == 10
raises(TypeError, lambda: Rational(2)*MyInt)
def test_SAGE2():
class MyInt(object):
def __int__(self):
return 5
assert sympify(MyInt()) == 5
e = Rational(2)*MyInt()
assert e == 10
raises(TypeError, lambda: Rational(2)*MyInt)
def test_SAGE3():
class MySymbol:
def __rmul__(self, other):
return ('mys', other, self)
o = MySymbol()
e = x*o
assert e == ('mys', x, o)
def test_len():
e = x*y
assert len(e.args) == 2
e = x + y + z
assert len(e.args) == 3
def test_doit():
a = Integral(x**2, x)
assert isinstance(a.doit(), Integral) is False
assert isinstance(a.doit(integrals=True), Integral) is False
assert isinstance(a.doit(integrals=False), Integral) is True
assert (2*Integral(x, x)).doit() == x**2
def test_attribute_error():
raises(AttributeError, lambda: x.cos())
raises(AttributeError, lambda: x.sin())
raises(AttributeError, lambda: x.exp())
def test_args():
assert (x*y).args in ((x, y), (y, x))
assert (x + y).args in ((x, y), (y, x))
assert (x*y + 1).args in ((x*y, 1), (1, x*y))
assert sin(x*y).args == (x*y,)
assert sin(x*y).args[0] == x*y
assert (x**y).args == (x, y)
assert (x**y).args[0] == x
assert (x**y).args[1] == y
def test_noncommutative_expand_issue_3757():
A, B, C = symbols('A,B,C', commutative=False)
assert A*B - B*A != 0
assert (A*(A + B)*B).expand() == A**2*B + A*B**2
assert (A*(A + B + C)*B).expand() == A**2*B + A*B**2 + A*C*B
def test_as_numer_denom():
a, b, c = symbols('a, b, c')
assert nan.as_numer_denom() == (nan, 1)
assert oo.as_numer_denom() == (oo, 1)
assert (-oo).as_numer_denom() == (-oo, 1)
assert zoo.as_numer_denom() == (zoo, 1)
assert (-zoo).as_numer_denom() == (zoo, 1)
assert x.as_numer_denom() == (x, 1)
assert (1/x).as_numer_denom() == (1, x)
assert (x/y).as_numer_denom() == (x, y)
assert (x/2).as_numer_denom() == (x, 2)
assert (x*y/z).as_numer_denom() == (x*y, z)
assert (x/(y*z)).as_numer_denom() == (x, y*z)
assert Rational(1, 2).as_numer_denom() == (1, 2)
assert (1/y**2).as_numer_denom() == (1, y**2)
assert (x/y**2).as_numer_denom() == (x, y**2)
assert ((x**2 + 1)/y).as_numer_denom() == (x**2 + 1, y)
assert (x*(y + 1)/y**7).as_numer_denom() == (x*(y + 1), y**7)
assert (x**-2).as_numer_denom() == (1, x**2)
assert (a/x + b/2/x + c/3/x).as_numer_denom() == \
(6*a + 3*b + 2*c, 6*x)
assert (a/x + b/2/x + c/3/y).as_numer_denom() == \
(2*c*x + y*(6*a + 3*b), 6*x*y)
assert (a/x + b/2/x + c/.5/x).as_numer_denom() == \
(2*a + b + 4.0*c, 2*x)
# this should take no more than a few seconds
assert int(log(Add(*[Dummy()/i/x for i in range(1, 705)]
).as_numer_denom()[1]/x).n(4)) == 705
for i in [S.Infinity, S.NegativeInfinity, S.ComplexInfinity]:
assert (i + x/3).as_numer_denom() == \
(x + i, 3)
assert (S.Infinity + x/3 + y/4).as_numer_denom() == \
(4*x + 3*y + S.Infinity, 12)
assert (oo*x + zoo*y).as_numer_denom() == \
(zoo*y + oo*x, 1)
A, B, C = symbols('A,B,C', commutative=False)
assert (A*B*C**-1).as_numer_denom() == (A*B*C**-1, 1)
assert (A*B*C**-1/x).as_numer_denom() == (A*B*C**-1, x)
assert (C**-1*A*B).as_numer_denom() == (C**-1*A*B, 1)
assert (C**-1*A*B/x).as_numer_denom() == (C**-1*A*B, x)
assert ((A*B*C)**-1).as_numer_denom() == ((A*B*C)**-1, 1)
assert ((A*B*C)**-1/x).as_numer_denom() == ((A*B*C)**-1, x)
def test_trunc():
import math
x, y = symbols('x y')
assert math.trunc(2) == 2
assert math.trunc(4.57) == 4
assert math.trunc(-5.79) == -5
assert math.trunc(pi) == 3
assert math.trunc(log(7)) == 1
assert math.trunc(exp(5)) == 148
assert math.trunc(cos(pi)) == -1
assert math.trunc(sin(5)) == 0
raises(TypeError, lambda: math.trunc(x))
raises(TypeError, lambda: math.trunc(x + y**2))
raises(TypeError, lambda: math.trunc(oo))
def test_as_independent():
assert S.Zero.as_independent(x, as_Add=True) == (0, 0)
assert S.Zero.as_independent(x, as_Add=False) == (0, 0)
assert (2*x*sin(x) + y + x).as_independent(x) == (y, x + 2*x*sin(x))
assert (2*x*sin(x) + y + x).as_independent(y) == (x + 2*x*sin(x), y)
assert (2*x*sin(x) + y + x).as_independent(x, y) == (0, y + x + 2*x*sin(x))
assert (x*sin(x)*cos(y)).as_independent(x) == (cos(y), x*sin(x))
assert (x*sin(x)*cos(y)).as_independent(y) == (x*sin(x), cos(y))
assert (x*sin(x)*cos(y)).as_independent(x, y) == (1, x*sin(x)*cos(y))
assert (sin(x)).as_independent(x) == (1, sin(x))
assert (sin(x)).as_independent(y) == (sin(x), 1)
assert (2*sin(x)).as_independent(x) == (2, sin(x))
assert (2*sin(x)).as_independent(y) == (2*sin(x), 1)
# issue 4903 = 1766b
n1, n2, n3 = symbols('n1 n2 n3', commutative=False)
assert (n1 + n1*n2).as_independent(n2) == (n1, n1*n2)
assert (n2*n1 + n1*n2).as_independent(n2) == (0, n1*n2 + n2*n1)
assert (n1*n2*n1).as_independent(n2) == (n1, n2*n1)
assert (n1*n2*n1).as_independent(n1) == (1, n1*n2*n1)
assert (3*x).as_independent(x, as_Add=True) == (0, 3*x)
assert (3*x).as_independent(x, as_Add=False) == (3, x)
assert (3 + x).as_independent(x, as_Add=True) == (3, x)
assert (3 + x).as_independent(x, as_Add=False) == (1, 3 + x)
# issue 5479
assert (3*x).as_independent(Symbol) == (3, x)
# issue 5648
assert (n1*x*y).as_independent(x) == (n1*y, x)
assert ((x + n1)*(x - y)).as_independent(x) == (1, (x + n1)*(x - y))
assert ((x + n1)*(x - y)).as_independent(y) == (x + n1, x - y)
assert (DiracDelta(x - n1)*DiracDelta(x - y)).as_independent(x) \
== (1, DiracDelta(x - n1)*DiracDelta(x - y))
assert (x*y*n1*n2*n3).as_independent(n2) == (x*y*n1, n2*n3)
assert (x*y*n1*n2*n3).as_independent(n1) == (x*y, n1*n2*n3)
assert (x*y*n1*n2*n3).as_independent(n3) == (x*y*n1*n2, n3)
assert (DiracDelta(x - n1)*DiracDelta(y - n1)*DiracDelta(x - n2)).as_independent(y) == \
(DiracDelta(x - n1)*DiracDelta(x - n2), DiracDelta(y - n1))
# issue 5784
assert (x + Integral(x, (x, 1, 2))).as_independent(x, strict=True) == \
(Integral(x, (x, 1, 2)), x)
eq = Add(x, -x, 2, -3, evaluate=False)
assert eq.as_independent(x) == (-1, Add(x, -x, evaluate=False))
eq = Mul(x, 1/x, 2, -3, evaluate=False)
eq.as_independent(x) == (-6, Mul(x, 1/x, evaluate=False))
assert (x*y).as_independent(z, as_Add=True) == (x*y, 0)
@XFAIL
def test_call_2():
# TODO UndefinedFunction does not subclass Expr
f = Function('f')
assert (2*f)(x) == 2*f(x)
def test_replace():
f = log(sin(x)) + tan(sin(x**2))
assert f.replace(sin, cos) == log(cos(x)) + tan(cos(x**2))
assert f.replace(
sin, lambda a: sin(2*a)) == log(sin(2*x)) + tan(sin(2*x**2))
a = Wild('a')
b = Wild('b')
assert f.replace(sin(a), cos(a)) == log(cos(x)) + tan(cos(x**2))
assert f.replace(
sin(a), lambda a: sin(2*a)) == log(sin(2*x)) + tan(sin(2*x**2))
# test exact
assert (2*x).replace(a*x + b, b - a, exact=True) == 2*x
assert (2*x).replace(a*x + b, b - a) == 2/x
assert (2*x).replace(a*x + b, lambda a, b: b - a, exact=True) == 2*x
assert (2*x).replace(a*x + b, lambda a, b: b - a) == 2/x
g = 2*sin(x**3)
assert g.replace(
lambda expr: expr.is_Number, lambda expr: expr**2) == 4*sin(x**9)
assert cos(x).replace(cos, sin, map=True) == (sin(x), {cos(x): sin(x)})
assert sin(x).replace(cos, sin) == sin(x)
cond, func = lambda x: x.is_Mul, lambda x: 2*x
assert (x*y).replace(cond, func, map=True) == (2*x*y, {x*y: 2*x*y})
assert (x*(1 + x*y)).replace(cond, func, map=True) == \
(2*x*(2*x*y + 1), {x*(2*x*y + 1): 2*x*(2*x*y + 1), x*y: 2*x*y})
assert (y*sin(x)).replace(sin, lambda expr: sin(expr)/y, map=True) == \
(sin(x), {sin(x): sin(x)/y})
# if not simultaneous then y*sin(x) -> y*sin(x)/y = sin(x) -> sin(x)/y
assert (y*sin(x)).replace(sin, lambda expr: sin(expr)/y,
simultaneous=False) == sin(x)/y
assert (x**2 + O(x**3)).replace(Pow, lambda b, e: b**e/e) == O(1, x)
assert (x**2 + O(x**3)).replace(Pow, lambda b, e: b**e/e,
simultaneous=False) == x**2/2 + O(x**3)
assert (x*(x*y + 3)).replace(lambda x: x.is_Mul, lambda x: 2 + x) == \
x*(x*y + 5) + 2
e = (x*y + 1)*(2*x*y + 1) + 1
assert e.replace(cond, func, map=True) == (
2*((2*x*y + 1)*(4*x*y + 1)) + 1,
{2*x*y: 4*x*y, x*y: 2*x*y, (2*x*y + 1)*(4*x*y + 1):
2*((2*x*y + 1)*(4*x*y + 1))})
assert x.replace(x, y) == y
assert (x + 1).replace(1, 2) == x + 2
# https://groups.google.com/forum/#!topic/sympy/8wCgeC95tz0
n1, n2, n3 = symbols('n1:4', commutative=False)
f = Function('f')
assert (n1*f(n2)).replace(f, lambda x: x) == n1*n2
assert (n3*f(n2)).replace(f, lambda x: x) == n3*n2
def test_find():
expr = (x + y + 2 + sin(3*x))
assert expr.find(lambda u: u.is_Integer) == {S(2), S(3)}
assert expr.find(lambda u: u.is_Symbol) == {x, y}
assert expr.find(lambda u: u.is_Integer, group=True) == {S(2): 1, S(3): 1}
assert expr.find(lambda u: u.is_Symbol, group=True) == {x: 2, y: 1}
assert expr.find(Integer) == {S(2), S(3)}
assert expr.find(Symbol) == {x, y}
assert expr.find(Integer, group=True) == {S(2): 1, S(3): 1}
assert expr.find(Symbol, group=True) == {x: 2, y: 1}
a = Wild('a')
expr = sin(sin(x)) + sin(x) + cos(x) + x
assert expr.find(lambda u: type(u) is sin) == {sin(x), sin(sin(x))}
assert expr.find(
lambda u: type(u) is sin, group=True) == {sin(x): 2, sin(sin(x)): 1}
assert expr.find(sin(a)) == {sin(x), sin(sin(x))}
assert expr.find(sin(a), group=True) == {sin(x): 2, sin(sin(x)): 1}
assert expr.find(sin) == {sin(x), sin(sin(x))}
assert expr.find(sin, group=True) == {sin(x): 2, sin(sin(x)): 1}
def test_count():
expr = (x + y + 2 + sin(3*x))
assert expr.count(lambda u: u.is_Integer) == 2
assert expr.count(lambda u: u.is_Symbol) == 3
assert expr.count(Integer) == 2
assert expr.count(Symbol) == 3
assert expr.count(2) == 1
a = Wild('a')
assert expr.count(sin) == 1
assert expr.count(sin(a)) == 1
assert expr.count(lambda u: type(u) is sin) == 1
f = Function('f')
assert f(x).count(f(x)) == 1
assert f(x).diff(x).count(f(x)) == 1
assert f(x).diff(x).count(x) == 2
def test_has_basics():
f = Function('f')
g = Function('g')
p = Wild('p')
assert sin(x).has(x)
assert sin(x).has(sin)
assert not sin(x).has(y)
assert not sin(x).has(cos)
assert f(x).has(x)
assert f(x).has(f)
assert not f(x).has(y)
assert not f(x).has(g)
assert f(x).diff(x).has(x)
assert f(x).diff(x).has(f)
assert f(x).diff(x).has(Derivative)
assert not f(x).diff(x).has(y)
assert not f(x).diff(x).has(g)
assert not f(x).diff(x).has(sin)
assert (x**2).has(Symbol)
assert not (x**2).has(Wild)
assert (2*p).has(Wild)
assert not x.has()
def test_has_multiple():
f = x**2*y + sin(2**t + log(z))
assert f.has(x)
assert f.has(y)
assert f.has(z)
assert f.has(t)
assert not f.has(u)
assert f.has(x, y, z, t)
assert f.has(x, y, z, t, u)
i = Integer(4400)
assert not i.has(x)
assert (i*x**i).has(x)
assert not (i*y**i).has(x)
assert (i*y**i).has(x, y)
assert not (i*y**i).has(x, z)
def test_has_piecewise():
f = (x*y + 3/y)**(3 + 2)
g = Function('g')
h = Function('h')
p = Piecewise((g(x), x < -1), (1, x <= 1), (f, True))
assert p.has(x)
assert p.has(y)
assert not p.has(z)
assert p.has(1)
assert p.has(3)
assert not p.has(4)
assert p.has(f)
assert p.has(g)
assert not p.has(h)
def test_has_iterative():
A, B, C = symbols('A,B,C', commutative=False)
f = x*gamma(x)*sin(x)*exp(x*y)*A*B*C*cos(x*A*B)
assert f.has(x)
assert f.has(x*y)
assert f.has(x*sin(x))
assert not f.has(x*sin(y))
assert f.has(x*A)
assert f.has(x*A*B)
assert not f.has(x*A*C)
assert f.has(x*A*B*C)
assert not f.has(x*A*C*B)
assert f.has(x*sin(x)*A*B*C)
assert not f.has(x*sin(x)*A*C*B)
assert not f.has(x*sin(y)*A*B*C)
assert f.has(x*gamma(x))
assert not f.has(x + sin(x))
assert (x & y & z).has(x & z)
def test_has_integrals():
f = Integral(x**2 + sin(x*y*z), (x, 0, x + y + z))
assert f.has(x + y)
assert f.has(x + z)
assert f.has(y + z)
assert f.has(x*y)
assert f.has(x*z)
assert f.has(y*z)
assert not f.has(2*x + y)
assert not f.has(2*x*y)
def test_has_tuple():
f = Function('f')
g = Function('g')
h = Function('h')
assert Tuple(x, y).has(x)
assert not Tuple(x, y).has(z)
assert Tuple(f(x), g(x)).has(x)
assert not Tuple(f(x), g(x)).has(y)
assert Tuple(f(x), g(x)).has(f)
assert Tuple(f(x), g(x)).has(f(x))
assert not Tuple(f, g).has(x)
assert Tuple(f, g).has(f)
assert not Tuple(f, g).has(h)
assert Tuple(True).has(True) is True # .has(1) will also be True
def test_has_units():
from sympy.physics.units import m, s
assert (x*m/s).has(x)
assert (x*m/s).has(y, z) is False
def test_has_polys():
poly = Poly(x**2 + x*y*sin(z), x, y, t)
assert poly.has(x)
assert poly.has(x, y, z)
assert poly.has(x, y, z, t)
def test_has_physics():
assert FockState((x, y)).has(x)
def test_as_poly_as_expr():
f = x**2 + 2*x*y
assert f.as_poly().as_expr() == f
assert f.as_poly(x, y).as_expr() == f
assert (f + sin(x)).as_poly(x, y) is None
p = Poly(f, x, y)
assert p.as_poly() == p
def test_nonzero():
assert bool(S.Zero) is False
assert bool(S.One) is True
assert bool(x) is True
assert bool(x + y) is True
assert bool(x - x) is False
assert bool(x*y) is True
assert bool(x*1) is True
assert bool(x*0) is False
def test_is_number():
assert Float(3.14).is_number is True
assert Integer(737).is_number is True
assert Rational(3, 2).is_number is True
assert Rational(8).is_number is True
assert x.is_number is False
assert (2*x).is_number is False
assert (x + y).is_number is False
assert log(2).is_number is True
assert log(x).is_number is False
assert (2 + log(2)).is_number is True
assert (8 + log(2)).is_number is True
assert (2 + log(x)).is_number is False
assert (8 + log(2) + x).is_number is False
assert (1 + x**2/x - x).is_number is True
assert Tuple(Integer(1)).is_number is False
assert Add(2, x).is_number is False
assert Mul(3, 4).is_number is True
assert Pow(log(2), 2).is_number is True
assert oo.is_number is True
g = WildFunction('g')
assert g.is_number is False
assert (2*g).is_number is False
assert (x**2).subs(x, 3).is_number is True
# test extensibility of .is_number
# on subinstances of Basic
class A(Basic):
pass
a = A()
assert a.is_number is False
def test_as_coeff_add():
assert S(2).as_coeff_add() == (2, ())
assert S(3.0).as_coeff_add() == (0, (S(3.0),))
assert S(-3.0).as_coeff_add() == (0, (S(-3.0),))
assert x.as_coeff_add() == (0, (x,))
assert (x - 1).as_coeff_add() == (-1, (x,))
assert (x + 1).as_coeff_add() == (1, (x,))
assert (x + 2).as_coeff_add() == (2, (x,))
assert (x + y).as_coeff_add(y) == (x, (y,))
assert (3*x).as_coeff_add(y) == (3*x, ())
# don't do expansion
e = (x + y)**2
assert e.as_coeff_add(y) == (0, (e,))
def test_as_coeff_mul():
assert S(2).as_coeff_mul() == (2, ())
assert S(3.0).as_coeff_mul() == (1, (S(3.0),))
assert S(-3.0).as_coeff_mul() == (-1, (S(3.0),))
assert S(-3.0).as_coeff_mul(rational=False) == (-S(3.0), ())
assert x.as_coeff_mul() == (1, (x,))
assert (-x).as_coeff_mul() == (-1, (x,))
assert (2*x).as_coeff_mul() == (2, (x,))
assert (x*y).as_coeff_mul(y) == (x, (y,))
assert (3 + x).as_coeff_mul() == (1, (3 + x,))
assert (3 + x).as_coeff_mul(y) == (3 + x, ())
# don't do expansion
e = exp(x + y)
assert e.as_coeff_mul(y) == (1, (e,))
e = 2**(x + y)
assert e.as_coeff_mul(y) == (1, (e,))
assert (1.1*x).as_coeff_mul(rational=False) == (1.1, (x,))
assert (1.1*x).as_coeff_mul() == (1, (1.1, x))
assert (-oo*x).as_coeff_mul(rational=True) == (-1, (oo, x))
def test_as_coeff_exponent():
assert (3*x**4).as_coeff_exponent(x) == (3, 4)
assert (2*x**3).as_coeff_exponent(x) == (2, 3)
assert (4*x**2).as_coeff_exponent(x) == (4, 2)
assert (6*x**1).as_coeff_exponent(x) == (6, 1)
assert (3*x**0).as_coeff_exponent(x) == (3, 0)
assert (2*x**0).as_coeff_exponent(x) == (2, 0)
assert (1*x**0).as_coeff_exponent(x) == (1, 0)
assert (0*x**0).as_coeff_exponent(x) == (0, 0)
assert (-1*x**0).as_coeff_exponent(x) == (-1, 0)
assert (-2*x**0).as_coeff_exponent(x) == (-2, 0)
assert (2*x**3 + pi*x**3).as_coeff_exponent(x) == (2 + pi, 3)
assert (x*log(2)/(2*x + pi*x)).as_coeff_exponent(x) == \
(log(2)/(2 + pi), 0)
# issue 4784
D = Derivative
f = Function('f')
fx = D(f(x), x)
assert fx.as_coeff_exponent(f(x)) == (fx, 0)
def test_extractions():
assert ((x*y)**3).extract_multiplicatively(x**2 * y) == x*y**2
assert ((x*y)**3).extract_multiplicatively(x**4 * y) is None
assert (2*x).extract_multiplicatively(2) == x
assert (2*x).extract_multiplicatively(3) is None
assert (2*x).extract_multiplicatively(-1) is None
assert (Rational(1, 2)*x).extract_multiplicatively(3) == x/6
assert (sqrt(x)).extract_multiplicatively(x) is None
assert (sqrt(x)).extract_multiplicatively(1/x) is None
assert x.extract_multiplicatively(-x) is None
assert (-2 - 4*I).extract_multiplicatively(-2) == 1 + 2*I
assert (-2 - 4*I).extract_multiplicatively(3) is None
assert (-2*x - 4*y - 8).extract_multiplicatively(-2) == x + 2*y + 4
assert (-2*x*y - 4*x**2*y).extract_multiplicatively(-2*y) == 2*x**2 + x
assert (2*x*y + 4*x**2*y).extract_multiplicatively(2*y) == 2*x**2 + x
assert (-4*y**2*x).extract_multiplicatively(-3*y) is None
assert (2*x).extract_multiplicatively(1) == 2*x
assert (-oo).extract_multiplicatively(5) == -oo
assert (oo).extract_multiplicatively(5) == oo
assert ((x*y)**3).extract_additively(1) is None
assert (x + 1).extract_additively(x) == 1
assert (x + 1).extract_additively(2*x) is None
assert (x + 1).extract_additively(-x) is None
assert (-x + 1).extract_additively(2*x) is None
assert (2*x + 3).extract_additively(x) == x + 3
assert (2*x + 3).extract_additively(2) == 2*x + 1
assert (2*x + 3).extract_additively(3) == 2*x
assert (2*x + 3).extract_additively(-2) is None
assert (2*x + 3).extract_additively(3*x) is None
assert (2*x + 3).extract_additively(2*x) == 3
assert x.extract_additively(0) == x
assert S(2).extract_additively(x) is None
assert S(2.).extract_additively(2) == S.Zero
assert S(2*x + 3).extract_additively(x + 1) == x + 2
assert S(2*x + 3).extract_additively(y + 1) is None
assert S(2*x - 3).extract_additively(x + 1) is None
assert S(2*x - 3).extract_additively(y + z) is None
assert ((a + 1)*x*4 + y).extract_additively(x).expand() == \
4*a*x + 3*x + y
assert ((a + 1)*x*4 + 3*y).extract_additively(x + 2*y).expand() == \
4*a*x + 3*x + y
assert (y*(x + 1)).extract_additively(x + 1) is None
assert ((y + 1)*(x + 1) + 3).extract_additively(x + 1) == \
y*(x + 1) + 3
assert ((x + y)*(x + 1) + x + y + 3).extract_additively(x + y) == \
x*(x + y) + 3
assert (x + y + 2*((x + y)*(x + 1)) + 3).extract_additively((x + y)*(x + 1)) == \
x + y + (x + 1)*(x + y) + 3
assert ((y + 1)*(x + 2*y + 1) + 3).extract_additively(y + 1) == \
(x + 2*y)*(y + 1) + 3
n = Symbol("n", integer=True)
assert (Integer(-3)).could_extract_minus_sign() is True
assert (-n*x + x).could_extract_minus_sign() != \
(n*x - x).could_extract_minus_sign()
assert (x - y).could_extract_minus_sign() != \
(-x + y).could_extract_minus_sign()
assert (1 - x - y).could_extract_minus_sign() is True
assert (1 - x + y).could_extract_minus_sign() is False
assert ((-x - x*y)/y).could_extract_minus_sign() is True
assert (-(x + x*y)/y).could_extract_minus_sign() is True
assert ((x + x*y)/(-y)).could_extract_minus_sign() is True
assert ((x + x*y)/y).could_extract_minus_sign() is False
assert (x*(-x - x**3)).could_extract_minus_sign() is True
assert ((-x - y)/(x + y)).could_extract_minus_sign() is True
class sign_invariant(Function, Expr):
nargs = 1
def __neg__(self):
return self
foo = sign_invariant(x)
assert foo == -foo
assert foo.could_extract_minus_sign() is False
# The results of each of these will vary on different machines, e.g.
# the first one might be False and the other (then) is true or vice versa,
# so both are included.
assert ((-x - y)/(x - y)).could_extract_minus_sign() is False or \
((-x - y)/(y - x)).could_extract_minus_sign() is False
assert (x - y).could_extract_minus_sign() is False
assert (-x + y).could_extract_minus_sign() is True
def test_nan_extractions():
for r in (1, 0, I, nan):
assert nan.extract_additively(r) is None
assert nan.extract_multiplicatively(r) is None
def test_coeff():
assert (x + 1).coeff(x + 1) == 1
assert (3*x).coeff(0) == 0
assert (z*(1 + x)*x**2).coeff(1 + x) == z*x**2
assert (1 + 2*x*x**(1 + x)).coeff(x*x**(1 + x)) == 2
assert (1 + 2*x**(y + z)).coeff(x**(y + z)) == 2
assert (3 + 2*x + 4*x**2).coeff(1) == 0
assert (3 + 2*x + 4*x**2).coeff(-1) == 0
assert (3 + 2*x + 4*x**2).coeff(x) == 2
assert (3 + 2*x + 4*x**2).coeff(x**2) == 4
assert (3 + 2*x + 4*x**2).coeff(x**3) == 0
assert (-x/8 + x*y).coeff(x) == -S(1)/8 + y
assert (-x/8 + x*y).coeff(-x) == S(1)/8
assert (4*x).coeff(2*x) == 0
assert (2*x).coeff(2*x) == 1
assert (-oo*x).coeff(x*oo) == -1
assert (10*x).coeff(x, 0) == 0
assert (10*x).coeff(10*x, 0) == 0
n1, n2 = symbols('n1 n2', commutative=False)
assert (n1*n2).coeff(n1) == 1
assert (n1*n2).coeff(n2) == n1
assert (n1*n2 + x*n1).coeff(n1) == 1 # 1*n1*(n2+x)
assert (n2*n1 + x*n1).coeff(n1) == n2 + x
assert (n2*n1 + x*n1**2).coeff(n1) == n2
assert (n1**x).coeff(n1) == 0
assert (n1*n2 + n2*n1).coeff(n1) == 0
assert (2*(n1 + n2)*n2).coeff(n1 + n2, right=1) == n2
assert (2*(n1 + n2)*n2).coeff(n1 + n2, right=0) == 2
f = Function('f')
assert (2*f(x) + 3*f(x).diff(x)).coeff(f(x)) == 2
expr = z*(x + y)**2
expr2 = z*(x + y)**2 + z*(2*x + 2*y)**2
assert expr.coeff(z) == (x + y)**2
assert expr.coeff(x + y) == 0
assert expr2.coeff(z) == (x + y)**2 + (2*x + 2*y)**2
assert (x + y + 3*z).coeff(1) == x + y
assert (-x + 2*y).coeff(-1) == x
assert (x - 2*y).coeff(-1) == 2*y
assert (3 + 2*x + 4*x**2).coeff(1) == 0
assert (-x - 2*y).coeff(2) == -y
assert (x + sqrt(2)*x).coeff(sqrt(2)) == x
assert (3 + 2*x + 4*x**2).coeff(x) == 2
assert (3 + 2*x + 4*x**2).coeff(x**2) == 4
assert (3 + 2*x + 4*x**2).coeff(x**3) == 0
assert (z*(x + y)**2).coeff((x + y)**2) == z
assert (z*(x + y)**2).coeff(x + y) == 0
assert (2 + 2*x + (x + 1)*y).coeff(x + 1) == y
assert (x + 2*y + 3).coeff(1) == x
assert (x + 2*y + 3).coeff(x, 0) == 2*y + 3
assert (x**2 + 2*y + 3*x).coeff(x**2, 0) == 2*y + 3*x
assert x.coeff(0, 0) == 0
assert x.coeff(x, 0) == 0
n, m, o, l = symbols('n m o l', commutative=False)
assert n.coeff(n) == 1
assert y.coeff(n) == 0
assert (3*n).coeff(n) == 3
assert (2 + n).coeff(x*m) == 0
assert (2*x*n*m).coeff(x) == 2*n*m
assert (2 + n).coeff(x*m*n + y) == 0
assert (2*x*n*m).coeff(3*n) == 0
assert (n*m + m*n*m).coeff(n) == 1 + m
assert (n*m + m*n*m).coeff(n, right=True) == m # = (1 + m)*n*m
assert (n*m + m*n).coeff(n) == 0
assert (n*m + o*m*n).coeff(m*n) == o
assert (n*m + o*m*n).coeff(m*n, right=1) == 1
assert (n*m + n*m*n).coeff(n*m, right=1) == 1 + n # = n*m*(n + 1)
assert (x*y).coeff(z, 0) == x*y
def test_coeff2():
r, kappa = symbols('r, kappa')
psi = Function("psi")
g = 1/r**2 * (2*r*psi(r).diff(r, 1) + r**2 * psi(r).diff(r, 2))
g = g.expand()
assert g.coeff((psi(r).diff(r))) == 2/r
def test_coeff2_0():
r, kappa = symbols('r, kappa')
psi = Function("psi")
g = 1/r**2 * (2*r*psi(r).diff(r, 1) + r**2 * psi(r).diff(r, 2))
g = g.expand()
assert g.coeff(psi(r).diff(r, 2)) == 1
def test_coeff_expand():
expr = z*(x + y)**2
expr2 = z*(x + y)**2 + z*(2*x + 2*y)**2
assert expr.coeff(z) == (x + y)**2
assert expr2.coeff(z) == (x + y)**2 + (2*x + 2*y)**2
def test_integrate():
assert x.integrate(x) == x**2/2
assert x.integrate((x, 0, 1)) == S(1)/2
def test_as_base_exp():
assert x.as_base_exp() == (x, S.One)
assert (x*y*z).as_base_exp() == (x*y*z, S.One)
assert (x + y + z).as_base_exp() == (x + y + z, S.One)
assert ((x + y)**z).as_base_exp() == (x + y, z)
def test_issue_4963():
assert hasattr(Mul(x, y), "is_commutative")
assert hasattr(Mul(x, y, evaluate=False), "is_commutative")
assert hasattr(Pow(x, y), "is_commutative")
assert hasattr(Pow(x, y, evaluate=False), "is_commutative")
expr = Mul(Pow(2, 2, evaluate=False), 3, evaluate=False) + 1
assert hasattr(expr, "is_commutative")
def test_action_verbs():
assert nsimplify((1/(exp(3*pi*x/5) + 1))) == \
(1/(exp(3*pi*x/5) + 1)).nsimplify()
assert ratsimp(1/x + 1/y) == (1/x + 1/y).ratsimp()
assert trigsimp(log(x), deep=True) == (log(x)).trigsimp(deep=True)
assert radsimp(1/(2 + sqrt(2))) == (1/(2 + sqrt(2))).radsimp()
assert radsimp(1/(a + b*sqrt(c)), symbolic=False) == \
(1/(a + b*sqrt(c))).radsimp(symbolic=False)
assert powsimp(x**y*x**z*y**z, combine='all') == \
(x**y*x**z*y**z).powsimp(combine='all')
assert (x**t*y**t).powsimp(force=True) == (x*y)**t
assert simplify(x**y*x**z*y**z) == (x**y*x**z*y**z).simplify()
assert together(1/x + 1/y) == (1/x + 1/y).together()
assert collect(a*x**2 + b*x**2 + a*x - b*x + c, x) == \
(a*x**2 + b*x**2 + a*x - b*x + c).collect(x)
assert apart(y/(y + 2)/(y + 1), y) == (y/(y + 2)/(y + 1)).apart(y)
assert combsimp(y/(x + 2)/(x + 1)) == (y/(x + 2)/(x + 1)).combsimp()
assert gammasimp(gamma(x)/gamma(x-5)) == (gamma(x)/gamma(x-5)).gammasimp()
assert factor(x**2 + 5*x + 6) == (x**2 + 5*x + 6).factor()
assert refine(sqrt(x**2)) == sqrt(x**2).refine()
assert cancel((x**2 + 5*x + 6)/(x + 2)) == ((x**2 + 5*x + 6)/(x + 2)).cancel()
def test_as_powers_dict():
assert x.as_powers_dict() == {x: 1}
assert (x**y*z).as_powers_dict() == {x: y, z: 1}
assert Mul(2, 2, evaluate=False).as_powers_dict() == {S(2): S(2)}
assert (x*y).as_powers_dict()[z] == 0
assert (x + y).as_powers_dict()[z] == 0
def test_as_coefficients_dict():
check = [S(1), x, y, x*y, 1]
assert [Add(3*x, 2*x, y, 3).as_coefficients_dict()[i] for i in check] == \
[3, 5, 1, 0, 3]
assert [Add(3*x, 2*x, y, 3, evaluate=False).as_coefficients_dict()[i]
for i in check] == [3, 5, 1, 0, 3]
assert [(3*x*y).as_coefficients_dict()[i] for i in check] == \
[0, 0, 0, 3, 0]
assert [(3.0*x*y).as_coefficients_dict()[i] for i in check] == \
[0, 0, 0, 3.0, 0]
assert (3.0*x*y).as_coefficients_dict()[3.0*x*y] == 0
def test_args_cnc():
A = symbols('A', commutative=False)
assert (x + A).args_cnc() == \
[[], [x + A]]
assert (x + a).args_cnc() == \
[[a + x], []]
assert (x*a).args_cnc() == \
[[a, x], []]
assert (x*y*A*(A + 1)).args_cnc(cset=True) == \
[{x, y}, [A, 1 + A]]
assert Mul(x, x, evaluate=False).args_cnc(cset=True, warn=False) == \
[{x}, []]
assert Mul(x, x**2, evaluate=False).args_cnc(cset=True, warn=False) == \
[{x, x**2}, []]
raises(ValueError, lambda: Mul(x, x, evaluate=False).args_cnc(cset=True))
assert Mul(x, y, x, evaluate=False).args_cnc() == \
[[x, y, x], []]
# always split -1 from leading number
assert (-1.*x).args_cnc() == [[-1, 1.0, x], []]
def test_new_rawargs():
n = Symbol('n', commutative=False)
a = x + n
assert a.is_commutative is False
assert a._new_rawargs(x).is_commutative
assert a._new_rawargs(x, y).is_commutative
assert a._new_rawargs(x, n).is_commutative is False
assert a._new_rawargs(x, y, n).is_commutative is False
m = x*n
assert m.is_commutative is False
assert m._new_rawargs(x).is_commutative
assert m._new_rawargs(n).is_commutative is False
assert m._new_rawargs(x, y).is_commutative
assert m._new_rawargs(x, n).is_commutative is False
assert m._new_rawargs(x, y, n).is_commutative is False
assert m._new_rawargs(x, n, reeval=False).is_commutative is False
assert m._new_rawargs(S.One) is S.One
def test_issue_5226():
assert Add(evaluate=False) == 0
assert Mul(evaluate=False) == 1
assert Mul(x + y, evaluate=False).is_Add
def test_free_symbols():
# free_symbols should return the free symbols of an object
assert S(1).free_symbols == set()
assert (x).free_symbols == {x}
assert Integral(x, (x, 1, y)).free_symbols == {y}
assert (-Integral(x, (x, 1, y))).free_symbols == {y}
assert meter.free_symbols == set()
assert (meter**x).free_symbols == {x}
def test_issue_5300():
x = Symbol('x', commutative=False)
assert x*sqrt(2)/sqrt(6) == x*sqrt(3)/3
def test_floordiv():
from sympy.functions.elementary.integers import floor
assert x // y == floor(x / y)
def test_as_coeff_Mul():
assert S(0).as_coeff_Mul() == (S.One, S.Zero)
assert Integer(3).as_coeff_Mul() == (Integer(3), Integer(1))
assert Rational(3, 4).as_coeff_Mul() == (Rational(3, 4), Integer(1))
assert Float(5.0).as_coeff_Mul() == (Float(5.0), Integer(1))
assert (Integer(3)*x).as_coeff_Mul() == (Integer(3), x)
assert (Rational(3, 4)*x).as_coeff_Mul() == (Rational(3, 4), x)
assert (Float(5.0)*x).as_coeff_Mul() == (Float(5.0), x)
assert (Integer(3)*x*y).as_coeff_Mul() == (Integer(3), x*y)
assert (Rational(3, 4)*x*y).as_coeff_Mul() == (Rational(3, 4), x*y)
assert (Float(5.0)*x*y).as_coeff_Mul() == (Float(5.0), x*y)
assert (x).as_coeff_Mul() == (S.One, x)
assert (x*y).as_coeff_Mul() == (S.One, x*y)
assert (-oo*x).as_coeff_Mul(rational=True) == (-1, oo*x)
def test_as_coeff_Add():
assert Integer(3).as_coeff_Add() == (Integer(3), Integer(0))
assert Rational(3, 4).as_coeff_Add() == (Rational(3, 4), Integer(0))
assert Float(5.0).as_coeff_Add() == (Float(5.0), Integer(0))
assert (Integer(3) + x).as_coeff_Add() == (Integer(3), x)
assert (Rational(3, 4) + x).as_coeff_Add() == (Rational(3, 4), x)
assert (Float(5.0) + x).as_coeff_Add() == (Float(5.0), x)
assert (Float(5.0) + x).as_coeff_Add(rational=True) == (0, Float(5.0) + x)
assert (Integer(3) + x + y).as_coeff_Add() == (Integer(3), x + y)
assert (Rational(3, 4) + x + y).as_coeff_Add() == (Rational(3, 4), x + y)
assert (Float(5.0) + x + y).as_coeff_Add() == (Float(5.0), x + y)
assert (x).as_coeff_Add() == (S.Zero, x)
assert (x*y).as_coeff_Add() == (S.Zero, x*y)
def test_expr_sorting():
f, g = symbols('f,g', cls=Function)
exprs = [1/x**2, 1/x, sqrt(sqrt(x)), sqrt(x), x, sqrt(x)**3, x**2]
assert sorted(exprs, key=default_sort_key) == exprs
exprs = [x, 2*x, 2*x**2, 2*x**3, x**n, 2*x**n, sin(x), sin(x)**n,
sin(x**2), cos(x), cos(x**2), tan(x)]
assert sorted(exprs, key=default_sort_key) == exprs
exprs = [x + 1, x**2 + x + 1, x**3 + x**2 + x + 1]
assert sorted(exprs, key=default_sort_key) == exprs
exprs = [S(4), x - 3*I/2, x + 3*I/2, x - 4*I + 1, x + 4*I + 1]
assert sorted(exprs, key=default_sort_key) == exprs
exprs = [f(1), f(2), f(3), f(1, 2, 3), g(1), g(2), g(3), g(1, 2, 3)]
assert sorted(exprs, key=default_sort_key) == exprs
exprs = [f(x), g(x), exp(x), sin(x), cos(x), factorial(x)]
assert sorted(exprs, key=default_sort_key) == exprs
exprs = [Tuple(x, y), Tuple(x, z), Tuple(x, y, z)]
assert sorted(exprs, key=default_sort_key) == exprs
exprs = [[3], [1, 2]]
assert sorted(exprs, key=default_sort_key) == exprs
exprs = [[1, 2], [2, 3]]
assert sorted(exprs, key=default_sort_key) == exprs
exprs = [[1, 2], [1, 2, 3]]
assert sorted(exprs, key=default_sort_key) == exprs
exprs = [{x: -y}, {x: y}]
assert sorted(exprs, key=default_sort_key) == exprs
exprs = [{1}, {1, 2}]
assert sorted(exprs, key=default_sort_key) == exprs
a, b = exprs = [Dummy('x'), Dummy('x')]
assert sorted([b, a], key=default_sort_key) == exprs
def test_as_ordered_factors():
f, g = symbols('f,g', cls=Function)
assert x.as_ordered_factors() == [x]
assert (2*x*x**n*sin(x)*cos(x)).as_ordered_factors() \
== [Integer(2), x, x**n, sin(x), cos(x)]
args = [f(1), f(2), f(3), f(1, 2, 3), g(1), g(2), g(3), g(1, 2, 3)]
expr = Mul(*args)
assert expr.as_ordered_factors() == args
A, B = symbols('A,B', commutative=False)
assert (A*B).as_ordered_factors() == [A, B]
assert (B*A).as_ordered_factors() == [B, A]
def test_as_ordered_terms():
f, g = symbols('f,g', cls=Function)
assert x.as_ordered_terms() == [x]
assert (sin(x)**2*cos(x) + sin(x)*cos(x)**2 + 1).as_ordered_terms() \
== [sin(x)**2*cos(x), sin(x)*cos(x)**2, 1]
args = [f(1), f(2), f(3), f(1, 2, 3), g(1), g(2), g(3), g(1, 2, 3)]
expr = Add(*args)
assert expr.as_ordered_terms() == args
assert (1 + 4*sqrt(3)*pi*x).as_ordered_terms() == [4*pi*x*sqrt(3), 1]
assert ( 2 + 3*I).as_ordered_terms() == [2, 3*I]
assert (-2 + 3*I).as_ordered_terms() == [-2, 3*I]
assert ( 2 - 3*I).as_ordered_terms() == [2, -3*I]
assert (-2 - 3*I).as_ordered_terms() == [-2, -3*I]
assert ( 4 + 3*I).as_ordered_terms() == [4, 3*I]
assert (-4 + 3*I).as_ordered_terms() == [-4, 3*I]
assert ( 4 - 3*I).as_ordered_terms() == [4, -3*I]
assert (-4 - 3*I).as_ordered_terms() == [-4, -3*I]
f = x**2*y**2 + x*y**4 + y + 2
assert f.as_ordered_terms(order="lex") == [x**2*y**2, x*y**4, y, 2]
assert f.as_ordered_terms(order="grlex") == [x*y**4, x**2*y**2, y, 2]
assert f.as_ordered_terms(order="rev-lex") == [2, y, x*y**4, x**2*y**2]
assert f.as_ordered_terms(order="rev-grlex") == [2, y, x**2*y**2, x*y**4]
k = symbols('k')
assert k.as_ordered_terms(data=True) == ([(k, ((1.0, 0.0), (1,), ()))], [k])
def test_sort_key_atomic_expr():
from sympy.physics.units import m, s
assert sorted([-m, s], key=lambda arg: arg.sort_key()) == [-m, s]
def test_eval_interval():
assert exp(x)._eval_interval(*Tuple(x, 0, 1)) == exp(1) - exp(0)
# issue 4199
# first subs and limit gives NaN
a = x/y
assert a._eval_interval(x, S(0), oo)._eval_interval(y, oo, S(0)) is S.NaN
# second subs and limit gives NaN
assert a._eval_interval(x, S(0), oo)._eval_interval(y, S(0), oo) is S.NaN
# difference gives S.NaN
a = x - y
assert a._eval_interval(x, S(1), oo)._eval_interval(y, oo, S(1)) is S.NaN
raises(ValueError, lambda: x._eval_interval(x, None, None))
a = -y*Heaviside(x - y)
assert a._eval_interval(x, -oo, oo) == -y
assert a._eval_interval(x, oo, -oo) == y
def test_eval_interval_zoo():
# Test that limit is used when zoo is returned
assert Si(1/x)._eval_interval(x, S(0), S(1)) == -pi/2 + Si(1)
def test_primitive():
assert (3*(x + 1)**2).primitive() == (3, (x + 1)**2)
assert (6*x + 2).primitive() == (2, 3*x + 1)
assert (x/2 + 3).primitive() == (S(1)/2, x + 6)
eq = (6*x + 2)*(x/2 + 3)
assert eq.primitive()[0] == 1
eq = (2 + 2*x)**2
assert eq.primitive()[0] == 1
assert (4.0*x).primitive() == (1, 4.0*x)
assert (4.0*x + y/2).primitive() == (S.Half, 8.0*x + y)
assert (-2*x).primitive() == (2, -x)
assert Add(5*z/7, 0.5*x, 3*y/2, evaluate=False).primitive() == \
(S(1)/14, 7.0*x + 21*y + 10*z)
for i in [S.Infinity, S.NegativeInfinity, S.ComplexInfinity]:
assert (i + x/3).primitive() == \
(S(1)/3, i + x)
assert (S.Infinity + 2*x/3 + 4*y/7).primitive() == \
(S(1)/21, 14*x + 12*y + oo)
assert S.Zero.primitive() == (S.One, S.Zero)
def test_issue_5843():
a = 1 + x
assert (2*a).extract_multiplicatively(a) == 2
assert (4*a).extract_multiplicatively(2*a) == 2
assert ((3*a)*(2*a)).extract_multiplicatively(a) == 6*a
def test_is_constant():
from sympy.solvers.solvers import checksol
Sum(x, (x, 1, 10)).is_constant() is True
Sum(x, (x, 1, n)).is_constant() is False
Sum(x, (x, 1, n)).is_constant(y) is True
Sum(x, (x, 1, n)).is_constant(n) is False
Sum(x, (x, 1, n)).is_constant(x) is True
eq = a*cos(x)**2 + a*sin(x)**2 - a
eq.is_constant() is True
assert eq.subs({x: pi, a: 2}) == eq.subs({x: pi, a: 3}) == 0
assert x.is_constant() is False
assert x.is_constant(y) is True
assert checksol(x, x, Sum(x, (x, 1, n))) is False
assert checksol(x, x, Sum(x, (x, 1, n))) is False
f = Function('f')
assert f(1).is_constant
assert checksol(x, x, f(x)) is False
assert Pow(x, S(0), evaluate=False).is_constant() is True # == 1
assert Pow(S(0), x, evaluate=False).is_constant() is False # == 0 or 1
assert (2**x).is_constant() is False
assert Pow(S(2), S(3), evaluate=False).is_constant() is True
z1, z2 = symbols('z1 z2', zero=True)
assert (z1 + 2*z2).is_constant() is True
assert meter.is_constant() is True
assert (3*meter).is_constant() is True
assert (x*meter).is_constant() is False
assert Poly(3,x).is_constant() is True
def test_equals():
assert (-3 - sqrt(5) + (-sqrt(10)/2 - sqrt(2)/2)**2).equals(0)
assert (x**2 - 1).equals((x + 1)*(x - 1))
assert (cos(x)**2 + sin(x)**2).equals(1)
assert (a*cos(x)**2 + a*sin(x)**2).equals(a)
r = sqrt(2)
assert (-1/(r + r*x) + 1/r/(1 + x)).equals(0)
assert factorial(x + 1).equals((x + 1)*factorial(x))
assert sqrt(3).equals(2*sqrt(3)) is False
assert (sqrt(5)*sqrt(3)).equals(sqrt(3)) is False
assert (sqrt(5) + sqrt(3)).equals(0) is False
assert (sqrt(5) + pi).equals(0) is False
assert meter.equals(0) is False
assert (3*meter**2).equals(0) is False
eq = -(-1)**(S(3)/4)*6**(S(1)/4) + (-6)**(S(1)/4)*I
if eq != 0: # if canonicalization makes this zero, skip the test
assert eq.equals(0)
assert sqrt(x).equals(0) is False
# from integrate(x*sqrt(1 + 2*x), x);
# diff is zero only when assumptions allow
i = 2*sqrt(2)*x**(S(5)/2)*(1 + 1/(2*x))**(S(5)/2)/5 + \
2*sqrt(2)*x**(S(3)/2)*(1 + 1/(2*x))**(S(5)/2)/(-6 - 3/x)
ans = sqrt(2*x + 1)*(6*x**2 + x - 1)/15
diff = i - ans
assert diff.equals(0) is False
assert diff.subs(x, -S.Half/2) == 7*sqrt(2)/120
# there are regions for x for which the expression is True, for
# example, when x < -1/2 or x > 0 the expression is zero
p = Symbol('p', positive=True)
assert diff.subs(x, p).equals(0) is True
assert diff.subs(x, -1).equals(0) is True
# prove via minimal_polynomial or self-consistency
eq = sqrt(1 + sqrt(3)) + sqrt(3 + 3*sqrt(3)) - sqrt(10 + 6*sqrt(3))
assert eq.equals(0)
q = 3**Rational(1, 3) + 3
p = expand(q**3)**Rational(1, 3)
assert (p - q).equals(0)
# issue 6829
# eq = q*x + q/4 + x**4 + x**3 + 2*x**2 - S(1)/3
# z = eq.subs(x, solve(eq, x)[0])
q = symbols('q')
z = (q*(-sqrt(-2*(-(q - S(7)/8)**S(2)/8 - S(2197)/13824)**(S(1)/3) -
S(13)/12)/2 - sqrt((2*q - S(7)/4)/sqrt(-2*(-(q - S(7)/8)**S(2)/8 -
S(2197)/13824)**(S(1)/3) - S(13)/12) + 2*(-(q - S(7)/8)**S(2)/8 -
S(2197)/13824)**(S(1)/3) - S(13)/6)/2 - S(1)/4) + q/4 + (-sqrt(-2*(-(q
- S(7)/8)**S(2)/8 - S(2197)/13824)**(S(1)/3) - S(13)/12)/2 - sqrt((2*q
- S(7)/4)/sqrt(-2*(-(q - S(7)/8)**S(2)/8 - S(2197)/13824)**(S(1)/3) -
S(13)/12) + 2*(-(q - S(7)/8)**S(2)/8 - S(2197)/13824)**(S(1)/3) -
S(13)/6)/2 - S(1)/4)**4 + (-sqrt(-2*(-(q - S(7)/8)**S(2)/8 -
S(2197)/13824)**(S(1)/3) - S(13)/12)/2 - sqrt((2*q -
S(7)/4)/sqrt(-2*(-(q - S(7)/8)**S(2)/8 - S(2197)/13824)**(S(1)/3) -
S(13)/12) + 2*(-(q - S(7)/8)**S(2)/8 - S(2197)/13824)**(S(1)/3) -
S(13)/6)/2 - S(1)/4)**3 + 2*(-sqrt(-2*(-(q - S(7)/8)**S(2)/8 -
S(2197)/13824)**(S(1)/3) - S(13)/12)/2 - sqrt((2*q -
S(7)/4)/sqrt(-2*(-(q - S(7)/8)**S(2)/8 - S(2197)/13824)**(S(1)/3) -
S(13)/12) + 2*(-(q - S(7)/8)**S(2)/8 - S(2197)/13824)**(S(1)/3) -
S(13)/6)/2 - S(1)/4)**2 - S(1)/3)
assert z.equals(0)
def test_random():
from sympy import posify, lucas
assert posify(x)[0]._random() is not None
assert lucas(n)._random(2, -2, 0, -1, 1) is None
# issue 8662
assert Piecewise((Max(x, y), z))._random() is None
def test_round():
from sympy.abc import x
assert Float('0.1249999').round(2) == 0.12
d20 = 12345678901234567890
ans = S(d20).round(2)
assert ans.is_Float and ans == d20
ans = S(d20).round(-2)
assert ans.is_Float and ans == 12345678901234567900
assert S('1/7').round(4) == 0.1429
assert S('.[12345]').round(4) == 0.1235
assert S('.1349').round(2) == 0.13
n = S(12345)
ans = n.round()
assert ans.is_Float
assert ans == n
ans = n.round(1)
assert ans.is_Float
assert ans == n
ans = n.round(4)
assert ans.is_Float
assert ans == n
assert n.round(-1) == 12350
r = n.round(-4)
assert r == 10000
# in fact, it should equal many values since __eq__
# compares at equal precision
assert all(r == i for i in range(9984, 10049))
assert n.round(-5) == 0
assert (pi + sqrt(2)).round(2) == 4.56
assert (10*(pi + sqrt(2))).round(-1) == 50
raises(TypeError, lambda: round(x + 2, 2))
assert S(2.3).round(1) == 2.3
e = S(12.345).round(2)
assert e == round(12.345, 2)
assert type(e) is Float
assert (Float(.3, 3) + 2*pi).round() == 7
assert (Float(.3, 3) + 2*pi*100).round() == 629
assert (Float(.03, 3) + 2*pi/100).round(5) == 0.09283
assert (Float(.03, 3) + 2*pi/100).round(4) == 0.0928
assert (pi + 2*E*I).round() == 3 + 5*I
assert S.Zero.round() == 0
a = (Add(1, Float('1.' + '9'*27, ''), evaluate=0))
assert a.round(10) == Float('3.0000000000', '')
assert a.round(25) == Float('3.0000000000000000000000000', '')
assert a.round(26) == Float('3.00000000000000000000000000', '')
assert a.round(27) == Float('2.999999999999999999999999999', '')
assert a.round(30) == Float('2.999999999999999999999999999', '')
raises(TypeError, lambda: x.round())
f = Function('f')
raises(TypeError, lambda: f(1).round())
# exact magnitude of 10
assert str(S(1).round()) == '1.'
assert str(S(100).round()) == '100.'
# applied to real and imaginary portions
assert (2*pi + E*I).round() == 6 + 3*I
assert (2*pi + I/10).round() == 6
assert (pi/10 + 2*I).round() == 2*I
# the lhs re and im parts are Float with dps of 2
# and those on the right have dps of 15 so they won't compare
# equal unless we use string or compare components (which will
# then coerce the floats to the same precision) or re-create
# the floats
assert str((pi/10 + E*I).round(2)) == '0.31 + 2.72*I'
assert (pi/10 + E*I).round(2).as_real_imag() == (0.31, 2.72)
assert (pi/10 + E*I).round(2) == Float(0.31, 2) + I*Float(2.72, 3)
# issue 6914
assert (I**(I + 3)).round(3) == Float('-0.208', '')*I
# issue 8720
assert S(-123.6).round() == -124.
assert S(-1.5).round() == -2.
assert S(-100.5).round() == -101.
assert S(-1.5 - 10.5*I).round() == -2.0 - 11.0*I
# issue 7961
assert str(S(0.006).round(2)) == '0.01'
assert str(S(0.00106).round(4)) == '0.0011'
# issue 8147
assert S.NaN.round() == S.NaN
assert S.Infinity.round() == S.Infinity
assert S.NegativeInfinity.round() == S.NegativeInfinity
assert S.ComplexInfinity.round() == S.ComplexInfinity
def test_held_expression_UnevaluatedExpr():
x = symbols("x")
he = UnevaluatedExpr(1/x)
e1 = x*he
assert isinstance(e1, Mul)
assert e1.args == (x, he)
assert e1.doit() == 1
assert UnevaluatedExpr(Derivative(x, x)).doit(deep=False
) == Derivative(x, x)
assert UnevaluatedExpr(Derivative(x, x)).doit() == 1
xx = Mul(x, x, evaluate=False)
assert xx != x**2
ue2 = UnevaluatedExpr(xx)
assert isinstance(ue2, UnevaluatedExpr)
assert ue2.args == (xx,)
assert ue2.doit() == x**2
assert ue2.doit(deep=False) == xx
x2 = UnevaluatedExpr(2)*2
assert type(x2) is Mul
assert x2.args == (2, UnevaluatedExpr(2))
def test_round_exception_nostr():
# Don't use the string form of the expression in the round exception, as
# it's too slow
s = Symbol('bad')
try:
s.round()
except TypeError as e:
assert 'bad' not in str(e)
else:
# Did not raise
raise AssertionError("Did not raise")
def test_extract_branch_factor():
assert exp_polar(2.0*I*pi).extract_branch_factor() == (1, 1)
def test_identity_removal():
assert Add.make_args(x + 0) == (x,)
assert Mul.make_args(x*1) == (x,)
def test_float_0():
assert Float(0.0) + 1 == Float(1.0)
@XFAIL
def test_float_0_fail():
assert Float(0.0)*x == Float(0.0)
assert (x + Float(0.0)).is_Add
def test_issue_6325():
ans = (b**2 + z**2 - (b*(a + b*t) + z*(c + t*z))**2/(
(a + b*t)**2 + (c + t*z)**2))/sqrt((a + b*t)**2 + (c + t*z)**2)
e = sqrt((a + b*t)**2 + (c + z*t)**2)
assert diff(e, t, 2) == ans
e.diff(t, 2) == ans
assert diff(e, t, 2, simplify=False) != ans
def test_issue_7426():
f1 = a % c
f2 = x % z
assert f1.equals(f2) is None
def test_issue_1112():
x = Symbol('x', positive=False)
assert (x > 0) is S.false
def test_issue_10161():
x = symbols('x', real=True)
assert x*abs(x)*abs(x) == x**3
def test_issue_10755():
x = symbols('x')
raises(TypeError, lambda: int(log(x)))
raises(TypeError, lambda: log(x).round(2))
def test_issue_11877():
x = symbols('x')
assert integrate(log(S(1)/2 - x), (x, 0, S(1)/2)) == -S(1)/2 -log(2)/2
def test_normal():
x = symbols('x')
e = Mul(S.Half, 1 + x, evaluate=False)
assert e.normal() == e
|
a88000d1307957b824b7fdc9e75684c7c7c0b37b5fef9d6b8321590d967c0bef
|
import decimal
from sympy import (Rational, Symbol, Float, I, sqrt, cbrt, oo, nan, pi, E,
Integer, S, factorial, Catalan, EulerGamma, GoldenRatio,
TribonacciConstant, cos, exp,
Number, zoo, log, Mul, Pow, Tuple, latex, Gt, Lt, Ge, Le,
AlgebraicNumber, simplify, sin, fibonacci, RealField,
sympify, srepr)
from sympy.core.compatibility import long
from sympy.core.power import integer_nthroot, isqrt, integer_log
from sympy.core.logic import fuzzy_not
from sympy.core.numbers import (igcd, ilcm, igcdex, seterr, _intcache,
igcd2, igcd_lehmer, mpf_norm, comp, mod_inverse)
from sympy.core.mod import Mod
from sympy.polys.domains.groundtypes import PythonRational
from sympy.utilities.decorator import conserve_mpmath_dps
from sympy.utilities.iterables import permutations
from sympy.utilities.pytest import XFAIL, raises
from mpmath import mpf
from mpmath.rational import mpq
import mpmath
t = Symbol('t', real=False)
def same_and_same_prec(a, b):
# stricter matching for Floats
return a == b and a._prec == b._prec
def test_integers_cache():
python_int = 2**65 + 3175259
while python_int in _intcache or hash(python_int) in _intcache:
python_int += 1
sympy_int = Integer(python_int)
assert python_int in _intcache
assert hash(python_int) not in _intcache
sympy_int_int = Integer(sympy_int)
assert python_int in _intcache
assert hash(python_int) not in _intcache
sympy_hash_int = Integer(hash(python_int))
assert python_int in _intcache
assert hash(python_int) in _intcache
def test_seterr():
seterr(divide=True)
raises(ValueError, lambda: S.Zero/S.Zero)
seterr(divide=False)
assert S.Zero / S.Zero == S.NaN
def test_mod():
x = Rational(1, 2)
y = Rational(3, 4)
z = Rational(5, 18043)
assert x % x == 0
assert x % y == 1/S(2)
assert x % z == 3/S(36086)
assert y % x == 1/S(4)
assert y % y == 0
assert y % z == 9/S(72172)
assert z % x == 5/S(18043)
assert z % y == 5/S(18043)
assert z % z == 0
a = Float(2.6)
assert (a % .2) == 0
assert (a % 2).round(15) == 0.6
assert (a % 0.5).round(15) == 0.1
p = Symbol('p', infinite=True)
assert oo % oo == nan
assert zoo % oo == nan
assert 5 % oo == nan
assert p % 5 == nan
# In these two tests, if the precision of m does
# not match the precision of the ans, then it is
# likely that the change made now gives an answer
# with degraded accuracy.
r = Rational(500, 41)
f = Float('.36', 3)
m = r % f
ans = Float(r % Rational(f), 3)
assert m == ans and m._prec == ans._prec
f = Float('8.36', 3)
m = f % r
ans = Float(Rational(f) % r, 3)
assert m == ans and m._prec == ans._prec
s = S.Zero
assert s % float(1) == S.Zero
# No rounding required since these numbers can be represented
# exactly.
assert Rational(3, 4) % Float(1.1) == 0.75
assert Float(1.5) % Rational(5, 4) == 0.25
assert Rational(5, 4).__rmod__(Float('1.5')) == 0.25
assert Float('1.5').__rmod__(Float('2.75')) == Float('1.25')
assert 2.75 % Float('1.5') == Float('1.25')
a = Integer(7)
b = Integer(4)
assert type(a % b) == Integer
assert a % b == Integer(3)
assert Integer(1) % Rational(2, 3) == Rational(1, 3)
assert Rational(7, 5) % Integer(1) == Rational(2, 5)
assert Integer(2) % 1.5 == 0.5
assert Integer(3).__rmod__(Integer(10)) == Integer(1)
assert Integer(10) % 4 == Integer(2)
assert 15 % Integer(4) == Integer(3)
def test_divmod():
assert divmod(S(12), S(8)) == Tuple(1, 4)
assert divmod(-S(12), S(8)) == Tuple(-2, 4)
assert divmod(S(0), S(1)) == Tuple(0, 0)
raises(ZeroDivisionError, lambda: divmod(S(0), S(0)))
raises(ZeroDivisionError, lambda: divmod(S(1), S(0)))
assert divmod(S(12), 8) == Tuple(1, 4)
assert divmod(12, S(8)) == Tuple(1, 4)
assert divmod(S("2"), S("3/2")) == Tuple(S("1"), S("1/2"))
assert divmod(S("3/2"), S("2")) == Tuple(S("0"), S("3/2"))
assert divmod(S("2"), S("3.5")) == Tuple(S("0"), S("2"))
assert divmod(S("3.5"), S("2")) == Tuple(S("1"), S("1.5"))
assert divmod(S("2"), S("1/3")) == Tuple(S("6"), S("0"))
assert divmod(S("1/3"), S("2")) == Tuple(S("0"), S("1/3"))
assert divmod(S("2"), S("0.1")) == Tuple(S("20"), S("0"))
assert divmod(S("0.1"), S("2")) == Tuple(S("0"), S("0.1"))
assert divmod(S("2"), 2) == Tuple(S("1"), S("0"))
assert divmod(2, S("2")) == Tuple(S("1"), S("0"))
assert divmod(S("2"), 1.5) == Tuple(S("1"), S("0.5"))
assert divmod(1.5, S("2")) == Tuple(S("0"), S("1.5"))
assert divmod(0.3, S("2")) == Tuple(S("0"), S("0.3"))
assert divmod(S("3/2"), S("3.5")) == Tuple(S("0"), S("3/2"))
assert divmod(S("3.5"), S("3/2")) == Tuple(S("2"), S("0.5"))
assert divmod(S("3/2"), S("1/3")) == Tuple(S("4"), Float("1/6"))
assert divmod(S("1/3"), S("3/2")) == Tuple(S("0"), S("1/3"))
assert divmod(S("3/2"), S("0.1")) == Tuple(S("15"), S("0"))
assert divmod(S("0.1"), S("3/2")) == Tuple(S("0"), S("0.1"))
assert divmod(S("3/2"), 2) == Tuple(S("0"), S("3/2"))
assert divmod(2, S("3/2")) == Tuple(S("1"), S("0.5"))
assert divmod(S("3/2"), 1.5) == Tuple(S("1"), S("0"))
assert divmod(1.5, S("3/2")) == Tuple(S("1"), S("0"))
assert divmod(S("3/2"), 0.3) == Tuple(S("5"), S("0"))
assert divmod(0.3, S("3/2")) == Tuple(S("0"), S("0.3"))
assert divmod(S("1/3"), S("3.5")) == Tuple(S("0"), S("1/3"))
assert divmod(S("3.5"), S("0.1")) == Tuple(S("35"), S("0"))
assert divmod(S("0.1"), S("3.5")) == Tuple(S("0"), S("0.1"))
assert divmod(S("3.5"), 2) == Tuple(S("1"), S("1.5"))
assert divmod(2, S("3.5")) == Tuple(S("0"), S("2"))
assert divmod(S("3.5"), 1.5) == Tuple(S("2"), S("0.5"))
assert divmod(1.5, S("3.5")) == Tuple(S("0"), S("1.5"))
assert divmod(0.3, S("3.5")) == Tuple(S("0"), S("0.3"))
assert divmod(S("0.1"), S("1/3")) == Tuple(S("0"), S("0.1"))
assert divmod(S("1/3"), 2) == Tuple(S("0"), S("1/3"))
assert divmod(2, S("1/3")) == Tuple(S("6"), S("0"))
assert divmod(S("1/3"), 1.5) == Tuple(S("0"), S("1/3"))
assert divmod(0.3, S("1/3")) == Tuple(S("0"), S("0.3"))
assert divmod(S("0.1"), 2) == Tuple(S("0"), S("0.1"))
assert divmod(2, S("0.1")) == Tuple(S("20"), S("0"))
assert divmod(S("0.1"), 1.5) == Tuple(S("0"), S("0.1"))
assert divmod(1.5, S("0.1")) == Tuple(S("15"), S("0"))
assert divmod(S("0.1"), 0.3) == Tuple(S("0"), S("0.1"))
assert str(divmod(S("2"), 0.3)) == '(6, 0.2)'
assert str(divmod(S("3.5"), S("1/3"))) == '(10, 0.166666666666667)'
assert str(divmod(S("3.5"), 0.3)) == '(11, 0.2)'
assert str(divmod(S("1/3"), S("0.1"))) == '(3, 0.0333333333333333)'
assert str(divmod(1.5, S("1/3"))) == '(4, 0.166666666666667)'
assert str(divmod(S("1/3"), 0.3)) == '(1, 0.0333333333333333)'
assert str(divmod(0.3, S("0.1"))) == '(2, 0.1)'
assert divmod(-3, S(2)) == (-2, 1)
assert divmod(S(-3), S(2)) == (-2, 1)
assert divmod(S(-3), 2) == (-2, 1)
assert divmod(S(4), S(-3.1)) == Tuple(-2, -2.2)
assert divmod(S(4), S(-2.1)) == divmod(4, -2.1)
assert divmod(S(-8), S(-2.5) ) == Tuple(3 , -0.5)
def test_igcd():
assert igcd(0, 0) == 0
assert igcd(0, 1) == 1
assert igcd(1, 0) == 1
assert igcd(0, 7) == 7
assert igcd(7, 0) == 7
assert igcd(7, 1) == 1
assert igcd(1, 7) == 1
assert igcd(-1, 0) == 1
assert igcd(0, -1) == 1
assert igcd(-1, -1) == 1
assert igcd(-1, 7) == 1
assert igcd(7, -1) == 1
assert igcd(8, 2) == 2
assert igcd(4, 8) == 4
assert igcd(8, 16) == 8
assert igcd(7, -3) == 1
assert igcd(-7, 3) == 1
assert igcd(-7, -3) == 1
assert igcd(*[10, 20, 30]) == 10
raises(TypeError, lambda: igcd())
raises(TypeError, lambda: igcd(2))
raises(ValueError, lambda: igcd(0, None))
raises(ValueError, lambda: igcd(1, 2.2))
for args in permutations((45.1, 1, 30)):
raises(ValueError, lambda: igcd(*args))
for args in permutations((1, 2, None)):
raises(ValueError, lambda: igcd(*args))
def test_igcd_lehmer():
a, b = fibonacci(10001), fibonacci(10000)
# len(str(a)) == 2090
# small divisors, long Euclidean sequence
assert igcd_lehmer(a, b) == 1
c = fibonacci(100)
assert igcd_lehmer(a*c, b*c) == c
# big divisor
assert igcd_lehmer(a, 10**1000) == 1
# swapping argmument
assert igcd_lehmer(1, 2) == igcd_lehmer(2, 1)
def test_igcd2():
# short loop
assert igcd2(2**100 - 1, 2**99 - 1) == 1
# Lehmer's algorithm
a, b = int(fibonacci(10001)), int(fibonacci(10000))
assert igcd2(a, b) == 1
def test_ilcm():
assert ilcm(0, 0) == 0
assert ilcm(1, 0) == 0
assert ilcm(0, 1) == 0
assert ilcm(1, 1) == 1
assert ilcm(2, 1) == 2
assert ilcm(8, 2) == 8
assert ilcm(8, 6) == 24
assert ilcm(8, 7) == 56
assert ilcm(*[10, 20, 30]) == 60
raises(ValueError, lambda: ilcm(8.1, 7))
raises(ValueError, lambda: ilcm(8, 7.1))
raises(TypeError, lambda: ilcm(8))
def test_igcdex():
assert igcdex(2, 3) == (-1, 1, 1)
assert igcdex(10, 12) == (-1, 1, 2)
assert igcdex(100, 2004) == (-20, 1, 4)
assert igcdex(0, 0) == (0, 1, 0)
assert igcdex(1, 0) == (1, 0, 1)
def _strictly_equal(a, b):
return (a.p, a.q, type(a.p), type(a.q)) == \
(b.p, b.q, type(b.p), type(b.q))
def _test_rational_new(cls):
"""
Tests that are common between Integer and Rational.
"""
assert cls(0) is S.Zero
assert cls(1) is S.One
assert cls(-1) is S.NegativeOne
# These look odd, but are similar to int():
assert cls('1') is S.One
assert cls(u'-1') is S.NegativeOne
i = Integer(10)
assert _strictly_equal(i, cls('10'))
assert _strictly_equal(i, cls(u'10'))
assert _strictly_equal(i, cls(long(10)))
assert _strictly_equal(i, cls(i))
raises(TypeError, lambda: cls(Symbol('x')))
def test_Integer_new():
"""
Test for Integer constructor
"""
_test_rational_new(Integer)
assert _strictly_equal(Integer(0.9), S.Zero)
assert _strictly_equal(Integer(10.5), Integer(10))
raises(ValueError, lambda: Integer("10.5"))
assert Integer(Rational('1.' + '9'*20)) == 1
def test_Rational_new():
""""
Test for Rational constructor
"""
_test_rational_new(Rational)
n1 = Rational(1, 2)
assert n1 == Rational(Integer(1), 2)
assert n1 == Rational(Integer(1), Integer(2))
assert n1 == Rational(1, Integer(2))
assert n1 == Rational(Rational(1, 2))
assert 1 == Rational(n1, n1)
assert Rational(3, 2) == Rational(Rational(1, 2), Rational(1, 3))
assert Rational(3, 1) == Rational(1, Rational(1, 3))
n3_4 = Rational(3, 4)
assert Rational('3/4') == n3_4
assert -Rational('-3/4') == n3_4
assert Rational('.76').limit_denominator(4) == n3_4
assert Rational(19, 25).limit_denominator(4) == n3_4
assert Rational('19/25').limit_denominator(4) == n3_4
assert Rational(1.0, 3) == Rational(1, 3)
assert Rational(1, 3.0) == Rational(1, 3)
assert Rational(Float(0.5)) == Rational(1, 2)
assert Rational('1e2/1e-2') == Rational(10000)
assert Rational('1 234') == Rational(1234)
assert Rational('1/1 234') == Rational(1, 1234)
assert Rational(-1, 0) == S.ComplexInfinity
assert Rational(1, 0) == S.ComplexInfinity
# Make sure Rational doesn't lose precision on Floats
assert Rational(pi.evalf(100)).evalf(100) == pi.evalf(100)
raises(TypeError, lambda: Rational('3**3'))
raises(TypeError, lambda: Rational('1/2 + 2/3'))
# handle fractions.Fraction instances
try:
import fractions
assert Rational(fractions.Fraction(1, 2)) == Rational(1, 2)
except ImportError:
pass
assert Rational(mpq(2, 6)) == Rational(1, 3)
assert Rational(PythonRational(2, 6)) == Rational(1, 3)
def test_Number_new():
""""
Test for Number constructor
"""
# Expected behavior on numbers and strings
assert Number(1) is S.One
assert Number(2).__class__ is Integer
assert Number(-622).__class__ is Integer
assert Number(5, 3).__class__ is Rational
assert Number(5.3).__class__ is Float
assert Number('1') is S.One
assert Number('2').__class__ is Integer
assert Number('-622').__class__ is Integer
assert Number('5/3').__class__ is Rational
assert Number('5.3').__class__ is Float
raises(ValueError, lambda: Number('cos'))
raises(TypeError, lambda: Number(cos))
a = Rational(3, 5)
assert Number(a) is a # Check idempotence on Numbers
def test_Number_cmp():
n1 = Number(1)
n2 = Number(2)
n3 = Number(-3)
assert n1 < n2
assert n1 <= n2
assert n3 < n1
assert n2 > n3
assert n2 >= n3
raises(TypeError, lambda: n1 < S.NaN)
raises(TypeError, lambda: n1 <= S.NaN)
raises(TypeError, lambda: n1 > S.NaN)
raises(TypeError, lambda: n1 >= S.NaN)
def test_Rational_cmp():
n1 = Rational(1, 4)
n2 = Rational(1, 3)
n3 = Rational(2, 4)
n4 = Rational(2, -4)
n5 = Rational(0)
n6 = Rational(1)
n7 = Rational(3)
n8 = Rational(-3)
assert n8 < n5
assert n5 < n6
assert n6 < n7
assert n8 < n7
assert n7 > n8
assert (n1 + 1)**n2 < 2
assert ((n1 + n6)/n7) < 1
assert n4 < n3
assert n2 < n3
assert n1 < n2
assert n3 > n1
assert not n3 < n1
assert not (Rational(-1) > 0)
assert Rational(-1) < 0
raises(TypeError, lambda: n1 < S.NaN)
raises(TypeError, lambda: n1 <= S.NaN)
raises(TypeError, lambda: n1 > S.NaN)
raises(TypeError, lambda: n1 >= S.NaN)
def test_Float():
def eq(a, b):
t = Float("1.0E-15")
return (-t < a - b < t)
a = Float(2) ** Float(3)
assert eq(a.evalf(), Float(8))
assert eq((pi ** -1).evalf(), Float("0.31830988618379067"))
a = Float(2) ** Float(4)
assert eq(a.evalf(), Float(16))
assert (S(.3) == S(.5)) is False
x_str = Float((0, '13333333333333', -52, 53))
x2_str = Float((0, '26666666666666', -53, 53))
x_hex = Float((0, long(0x13333333333333), -52, 53))
x_dec = Float((0, 5404319552844595, -52, 53))
assert x_str == x_hex == x_dec == Float(1.2)
# This looses a binary digit of precision, so it isn't equal to the above,
# but check that it normalizes correctly
x2_hex = Float((0, long(0x13333333333333)*2, -53, 53))
assert x2_hex._mpf_ == (0, 5404319552844595, -52, 52)
# XXX: Should this test also hold?
# assert x2_hex._prec == 52
# x2_str and 1.2 are superficially the same
assert str(x2_str) == str(Float(1.2))
# but are different at the mpf level
assert Float(1.2)._mpf_ == (0, long(5404319552844595), -52, 53)
assert x2_str._mpf_ == (0, long(10808639105689190), -53, 53)
assert Float((0, long(0), -123, -1)) == Float('nan')
assert Float((0, long(0), -456, -2)) == Float('inf') == Float('+inf')
assert Float((1, long(0), -789, -3)) == Float('-inf')
raises(ValueError, lambda: Float((0, 7, 1, 3), ''))
assert Float('+inf').is_finite is False
assert Float('+inf').is_negative is False
assert Float('+inf').is_positive is True
assert Float('+inf').is_infinite is True
assert Float('+inf').is_zero is False
assert Float('-inf').is_finite is False
assert Float('-inf').is_negative is True
assert Float('-inf').is_positive is False
assert Float('-inf').is_infinite is True
assert Float('-inf').is_zero is False
assert Float('0.0').is_finite is True
assert Float('0.0').is_negative is False
assert Float('0.0').is_positive is False
assert Float('0.0').is_infinite is False
assert Float('0.0').is_zero is True
# rationality properties
assert Float(1).is_rational is None
assert Float(1).is_irrational is None
assert sqrt(2).n(15).is_rational is None
assert sqrt(2).n(15).is_irrational is None
# do not automatically evalf
def teq(a):
assert (a.evalf() == a) is False
assert (a.evalf() != a) is True
assert (a == a.evalf()) is False
assert (a != a.evalf()) is True
teq(pi)
teq(2*pi)
teq(cos(0.1, evaluate=False))
# long integer
i = 12345678901234567890
assert same_and_same_prec(Float(12, ''), Float('12', ''))
assert same_and_same_prec(Float(Integer(i), ''), Float(i, ''))
assert same_and_same_prec(Float(i, ''), Float(str(i), 20))
assert same_and_same_prec(Float(str(i)), Float(i, ''))
assert same_and_same_prec(Float(i), Float(i, ''))
# inexact floats (repeating binary = denom not multiple of 2)
# cannot have precision greater than 15
assert Float(.125, 22) == .125
assert Float(2.0, 22) == 2
assert float(Float('.12500000000000001', '')) == .125
raises(ValueError, lambda: Float(.12500000000000001, ''))
# allow spaces
Float('123 456.123 456') == Float('123456.123456')
Integer('123 456') == Integer('123456')
Rational('123 456.123 456') == Rational('123456.123456')
assert Float(' .3e2') == Float('0.3e2')
# allow auto precision detection
assert Float('.1', '') == Float(.1, 1)
assert Float('.125', '') == Float(.125, 3)
assert Float('.100', '') == Float(.1, 3)
assert Float('2.0', '') == Float('2', 2)
raises(ValueError, lambda: Float("12.3d-4", ""))
raises(ValueError, lambda: Float(12.3, ""))
raises(ValueError, lambda: Float('.'))
raises(ValueError, lambda: Float('-.'))
zero = Float('0.0')
assert Float('-0') == zero
assert Float('.0') == zero
assert Float('-.0') == zero
assert Float('-0.0') == zero
assert Float(0.0) == zero
assert Float(0) == zero
assert Float(0, '') == Float('0', '')
assert Float(1) == Float(1.0)
assert Float(S.Zero) == zero
assert Float(S.One) == Float(1.0)
assert Float(decimal.Decimal('0.1'), 3) == Float('.1', 3)
assert Float(decimal.Decimal('nan')) == S.NaN
assert Float(decimal.Decimal('Infinity')) == S.Infinity
assert Float(decimal.Decimal('-Infinity')) == S.NegativeInfinity
assert '{0:.3f}'.format(Float(4.236622)) == '4.237'
assert '{0:.35f}'.format(Float(pi.n(40), 40)) == \
'3.14159265358979323846264338327950288'
assert Float(oo) == Float('+inf')
assert Float(-oo) == Float('-inf')
# unicode
assert Float(u'0.73908513321516064100000000') == \
Float('0.73908513321516064100000000')
assert Float(u'0.73908513321516064100000000', 28) == \
Float('0.73908513321516064100000000', 28)
# binary precision
# Decimal value 0.1 cannot be expressed precisely as a base 2 fraction
a = Float(S(1)/10, dps=15)
b = Float(S(1)/10, dps=16)
p = Float(S(1)/10, precision=53)
q = Float(S(1)/10, precision=54)
assert a._mpf_ == p._mpf_
assert not a._mpf_ == q._mpf_
assert not b._mpf_ == q._mpf_
# Precision specifying errors
raises(ValueError, lambda: Float("1.23", dps=3, precision=10))
raises(ValueError, lambda: Float("1.23", dps="", precision=10))
raises(ValueError, lambda: Float("1.23", dps=3, precision=""))
raises(ValueError, lambda: Float("1.23", dps="", precision=""))
# from NumberSymbol
assert same_and_same_prec(Float(pi, 32), pi.evalf(32))
assert same_and_same_prec(Float(Catalan), Catalan.evalf())
@conserve_mpmath_dps
def test_float_mpf():
import mpmath
mpmath.mp.dps = 100
mp_pi = mpmath.pi()
assert Float(mp_pi, 100) == Float(mp_pi._mpf_, 100) == pi.evalf(100)
mpmath.mp.dps = 15
assert Float(mp_pi, 100) == Float(mp_pi._mpf_, 100) == pi.evalf(100)
def test_Float_RealElement():
repi = RealField(dps=100)(pi.evalf(100))
# We still have to pass the precision because Float doesn't know what
# RealElement is, but make sure it keeps full precision from the result.
assert Float(repi, 100) == pi.evalf(100)
def test_Float_default_to_highprec_from_str():
s = str(pi.evalf(128))
assert same_and_same_prec(Float(s), Float(s, ''))
def test_Float_eval():
a = Float(3.2)
assert (a**2).is_Float
def test_Float_issue_2107():
a = Float(0.1, 10)
b = Float("0.1", 10)
assert a - a == 0
assert a + (-a) == 0
assert S.Zero + a - a == 0
assert S.Zero + a + (-a) == 0
assert b - b == 0
assert b + (-b) == 0
assert S.Zero + b - b == 0
assert S.Zero + b + (-b) == 0
def test_issue_14289():
from sympy.polys.numberfields import to_number_field
a = 1 - sqrt(2)
b = to_number_field(a)
assert b.as_expr() == a
assert b.minpoly(a).expand() == 0
def test_Float_from_tuple():
a = Float((0, '1L', 0, 1))
b = Float((0, '1', 0, 1))
assert a == b
def test_Infinity():
assert oo != 1
assert 1*oo == oo
assert 1 != oo
assert oo != -oo
assert oo != Symbol("x")**3
assert oo + 1 == oo
assert 2 + oo == oo
assert 3*oo + 2 == oo
assert S.Half**oo == 0
assert S.Half**(-oo) == oo
assert -oo*3 == -oo
assert oo + oo == oo
assert -oo + oo*(-5) == -oo
assert 1/oo == 0
assert 1/(-oo) == 0
assert 8/oo == 0
assert oo % 2 == nan
assert 2 % oo == nan
assert oo/oo == nan
assert oo/-oo == nan
assert -oo/oo == nan
assert -oo/-oo == nan
assert oo - oo == nan
assert oo - -oo == oo
assert -oo - oo == -oo
assert -oo - -oo == nan
assert oo + -oo == nan
assert -oo + oo == nan
assert oo + oo == oo
assert -oo + oo == nan
assert oo + -oo == nan
assert -oo + -oo == -oo
assert oo*oo == oo
assert -oo*oo == -oo
assert oo*-oo == -oo
assert -oo*-oo == oo
assert oo/0 == oo
assert -oo/0 == -oo
assert 0/oo == 0
assert 0/-oo == 0
assert oo*0 == nan
assert -oo*0 == nan
assert 0*oo == nan
assert 0*-oo == nan
assert oo + 0 == oo
assert -oo + 0 == -oo
assert 0 + oo == oo
assert 0 + -oo == -oo
assert oo - 0 == oo
assert -oo - 0 == -oo
assert 0 - oo == -oo
assert 0 - -oo == oo
assert oo/2 == oo
assert -oo/2 == -oo
assert oo/-2 == -oo
assert -oo/-2 == oo
assert oo*2 == oo
assert -oo*2 == -oo
assert oo*-2 == -oo
assert 2/oo == 0
assert 2/-oo == 0
assert -2/oo == 0
assert -2/-oo == 0
assert 2*oo == oo
assert 2*-oo == -oo
assert -2*oo == -oo
assert -2*-oo == oo
assert 2 + oo == oo
assert 2 - oo == -oo
assert -2 + oo == oo
assert -2 - oo == -oo
assert 2 + -oo == -oo
assert 2 - -oo == oo
assert -2 + -oo == -oo
assert -2 - -oo == oo
assert S(2) + oo == oo
assert S(2) - oo == -oo
assert oo/I == -oo*I
assert -oo/I == oo*I
assert oo*float(1) == Float('inf') and (oo*float(1)).is_Float
assert -oo*float(1) == Float('-inf') and (-oo*float(1)).is_Float
assert oo/float(1) == Float('inf') and (oo/float(1)).is_Float
assert -oo/float(1) == Float('-inf') and (-oo/float(1)).is_Float
assert oo*float(-1) == Float('-inf') and (oo*float(-1)).is_Float
assert -oo*float(-1) == Float('inf') and (-oo*float(-1)).is_Float
assert oo/float(-1) == Float('-inf') and (oo/float(-1)).is_Float
assert -oo/float(-1) == Float('inf') and (-oo/float(-1)).is_Float
assert oo + float(1) == Float('inf') and (oo + float(1)).is_Float
assert -oo + float(1) == Float('-inf') and (-oo + float(1)).is_Float
assert oo - float(1) == Float('inf') and (oo - float(1)).is_Float
assert -oo - float(1) == Float('-inf') and (-oo - float(1)).is_Float
assert float(1)*oo == Float('inf') and (float(1)*oo).is_Float
assert float(1)*-oo == Float('-inf') and (float(1)*-oo).is_Float
assert float(1)/oo == 0
assert float(1)/-oo == 0
assert float(-1)*oo == Float('-inf') and (float(-1)*oo).is_Float
assert float(-1)*-oo == Float('inf') and (float(-1)*-oo).is_Float
assert float(-1)/oo == 0
assert float(-1)/-oo == 0
assert float(1) + oo == Float('inf')
assert float(1) + -oo == Float('-inf')
assert float(1) - oo == Float('-inf')
assert float(1) - -oo == Float('inf')
assert Float('nan') == nan
assert nan*1.0 == nan
assert -1.0*nan == nan
assert nan*oo == nan
assert nan*-oo == nan
assert nan/oo == nan
assert nan/-oo == nan
assert nan + oo == nan
assert nan + -oo == nan
assert nan - oo == nan
assert nan - -oo == nan
assert -oo * S.Zero == nan
assert oo*nan == nan
assert -oo*nan == nan
assert oo/nan == nan
assert -oo/nan == nan
assert oo + nan == nan
assert -oo + nan == nan
assert oo - nan == nan
assert -oo - nan == nan
assert S.Zero * oo == nan
assert oo.is_Rational is False
assert isinstance(oo, Rational) is False
assert S.One/oo == 0
assert -S.One/oo == 0
assert S.One/-oo == 0
assert -S.One/-oo == 0
assert S.One*oo == oo
assert -S.One*oo == -oo
assert S.One*-oo == -oo
assert -S.One*-oo == oo
assert S.One/nan == nan
assert S.One - -oo == oo
assert S.One + nan == nan
assert S.One - nan == nan
assert nan - S.One == nan
assert nan/S.One == nan
assert -oo - S.One == -oo
def test_Infinity_2():
x = Symbol('x')
assert oo*x != oo
assert oo*(pi - 1) == oo
assert oo*(1 - pi) == -oo
assert (-oo)*x != -oo
assert (-oo)*(pi - 1) == -oo
assert (-oo)*(1 - pi) == oo
assert (-1)**S.NaN is S.NaN
assert oo - Float('inf') is S.NaN
assert oo + Float('-inf') is S.NaN
assert oo*0 is S.NaN
assert oo/Float('inf') is S.NaN
assert oo/Float('-inf') is S.NaN
assert oo**S.NaN is S.NaN
assert -oo + Float('inf') is S.NaN
assert -oo - Float('-inf') is S.NaN
assert -oo*S.NaN is S.NaN
assert -oo*0 is S.NaN
assert -oo/Float('inf') is S.NaN
assert -oo/Float('-inf') is S.NaN
assert -oo/S.NaN is S.NaN
assert abs(-oo) == oo
assert all((-oo)**i is S.NaN for i in (oo, -oo, S.NaN))
assert (-oo)**3 == -oo
assert (-oo)**2 == oo
assert abs(S.ComplexInfinity) == oo
def test_Mul_Infinity_Zero():
assert 0*Float('inf') == nan
assert 0*Float('-inf') == nan
assert 0*Float('inf') == nan
assert 0*Float('-inf') == nan
assert Float('inf')*0 == nan
assert Float('-inf')*0 == nan
assert Float('inf')*0 == nan
assert Float('-inf')*0 == nan
assert Float(0)*Float('inf') == nan
assert Float(0)*Float('-inf') == nan
assert Float(0)*Float('inf') == nan
assert Float(0)*Float('-inf') == nan
assert Float('inf')*Float(0) == nan
assert Float('-inf')*Float(0) == nan
assert Float('inf')*Float(0) == nan
assert Float('-inf')*Float(0) == nan
def test_Div_By_Zero():
assert 1/S(0) == zoo
assert 1/Float(0) == Float('inf')
assert 0/S(0) == nan
assert 0/Float(0) == nan
assert S(0)/0 == nan
assert Float(0)/0 == nan
assert -1/S(0) == zoo
assert -1/Float(0) == Float('-inf')
def test_Infinity_inequations():
assert oo > pi
assert not (oo < pi)
assert exp(-3) < oo
assert Float('+inf') > pi
assert not (Float('+inf') < pi)
assert exp(-3) < Float('+inf')
raises(TypeError, lambda: oo < I)
raises(TypeError, lambda: oo <= I)
raises(TypeError, lambda: oo > I)
raises(TypeError, lambda: oo >= I)
raises(TypeError, lambda: -oo < I)
raises(TypeError, lambda: -oo <= I)
raises(TypeError, lambda: -oo > I)
raises(TypeError, lambda: -oo >= I)
raises(TypeError, lambda: I < oo)
raises(TypeError, lambda: I <= oo)
raises(TypeError, lambda: I > oo)
raises(TypeError, lambda: I >= oo)
raises(TypeError, lambda: I < -oo)
raises(TypeError, lambda: I <= -oo)
raises(TypeError, lambda: I > -oo)
raises(TypeError, lambda: I >= -oo)
assert oo > -oo and oo >= -oo
assert (oo < -oo) == False and (oo <= -oo) == False
assert -oo < oo and -oo <= oo
assert (-oo > oo) == False and (-oo >= oo) == False
assert (oo < oo) == False # issue 7775
assert (oo > oo) == False
assert (-oo > -oo) == False and (-oo < -oo) == False
assert oo >= oo and oo <= oo and -oo >= -oo and -oo <= -oo
assert (-oo < -Float('inf')) == False
assert (oo > Float('inf')) == False
assert -oo >= -Float('inf')
assert oo <= Float('inf')
x = Symbol('x')
b = Symbol('b', finite=True, real=True)
assert (x < oo) == Lt(x, oo) # issue 7775
assert b < oo and b > -oo and b <= oo and b >= -oo
assert oo > b and oo >= b and (oo < b) == False and (oo <= b) == False
assert (-oo > b) == False and (-oo >= b) == False and -oo < b and -oo <= b
assert (oo < x) == Lt(oo, x) and (oo > x) == Gt(oo, x)
assert (oo <= x) == Le(oo, x) and (oo >= x) == Ge(oo, x)
assert (-oo < x) == Lt(-oo, x) and (-oo > x) == Gt(-oo, x)
assert (-oo <= x) == Le(-oo, x) and (-oo >= x) == Ge(-oo, x)
def test_NaN():
assert nan == nan
assert nan != 1
assert 1*nan == nan
assert 1 != nan
assert nan == -nan
assert oo != Symbol("x")**3
assert nan + 1 == nan
assert 2 + nan == nan
assert 3*nan + 2 == nan
assert -nan*3 == nan
assert nan + nan == nan
assert -nan + nan*(-5) == nan
assert 1/nan == nan
assert 1/(-nan) == nan
assert 8/nan == nan
raises(TypeError, lambda: nan > 0)
raises(TypeError, lambda: nan < 0)
raises(TypeError, lambda: nan >= 0)
raises(TypeError, lambda: nan <= 0)
raises(TypeError, lambda: 0 < nan)
raises(TypeError, lambda: 0 > nan)
raises(TypeError, lambda: 0 <= nan)
raises(TypeError, lambda: 0 >= nan)
assert S.One + nan == nan
assert S.One - nan == nan
assert S.One*nan == nan
assert S.One/nan == nan
assert nan - S.One == nan
assert nan*S.One == nan
assert nan + S.One == nan
assert nan/S.One == nan
assert nan**0 == 1 # as per IEEE 754
assert 1**nan == nan # IEEE 754 is not the best choice for symbolic work
# test Pow._eval_power's handling of NaN
assert Pow(nan, 0, evaluate=False)**2 == 1
def test_special_numbers():
assert isinstance(S.NaN, Number) is True
assert isinstance(S.Infinity, Number) is True
assert isinstance(S.NegativeInfinity, Number) is True
assert S.NaN.is_number is True
assert S.Infinity.is_number is True
assert S.NegativeInfinity.is_number is True
assert S.ComplexInfinity.is_number is True
assert isinstance(S.NaN, Rational) is False
assert isinstance(S.Infinity, Rational) is False
assert isinstance(S.NegativeInfinity, Rational) is False
assert S.NaN.is_rational is not True
assert S.Infinity.is_rational is not True
assert S.NegativeInfinity.is_rational is not True
def test_powers():
assert integer_nthroot(1, 2) == (1, True)
assert integer_nthroot(1, 5) == (1, True)
assert integer_nthroot(2, 1) == (2, True)
assert integer_nthroot(2, 2) == (1, False)
assert integer_nthroot(2, 5) == (1, False)
assert integer_nthroot(4, 2) == (2, True)
assert integer_nthroot(123**25, 25) == (123, True)
assert integer_nthroot(123**25 + 1, 25) == (123, False)
assert integer_nthroot(123**25 - 1, 25) == (122, False)
assert integer_nthroot(1, 1) == (1, True)
assert integer_nthroot(0, 1) == (0, True)
assert integer_nthroot(0, 3) == (0, True)
assert integer_nthroot(10000, 1) == (10000, True)
assert integer_nthroot(4, 2) == (2, True)
assert integer_nthroot(16, 2) == (4, True)
assert integer_nthroot(26, 2) == (5, False)
assert integer_nthroot(1234567**7, 7) == (1234567, True)
assert integer_nthroot(1234567**7 + 1, 7) == (1234567, False)
assert integer_nthroot(1234567**7 - 1, 7) == (1234566, False)
b = 25**1000
assert integer_nthroot(b, 1000) == (25, True)
assert integer_nthroot(b + 1, 1000) == (25, False)
assert integer_nthroot(b - 1, 1000) == (24, False)
c = 10**400
c2 = c**2
assert integer_nthroot(c2, 2) == (c, True)
assert integer_nthroot(c2 + 1, 2) == (c, False)
assert integer_nthroot(c2 - 1, 2) == (c - 1, False)
assert integer_nthroot(2, 10**10) == (1, False)
p, r = integer_nthroot(int(factorial(10000)), 100)
assert p % (10**10) == 5322420655
assert not r
# Test that this is fast
assert integer_nthroot(2, 10**10) == (1, False)
# output should be int if possible
assert type(integer_nthroot(2**61, 2)[0]) is int
def test_integer_nthroot_overflow():
assert integer_nthroot(10**(50*50), 50) == (10**50, True)
assert integer_nthroot(10**100000, 10000) == (10**10, True)
def test_integer_log():
raises(ValueError, lambda: integer_log(2, 1))
raises(ValueError, lambda: integer_log(0, 2))
raises(ValueError, lambda: integer_log(1.1, 2))
raises(ValueError, lambda: integer_log(1, 2.2))
assert integer_log(1, 2) == (0, True)
assert integer_log(1, 3) == (0, True)
assert integer_log(2, 3) == (0, False)
assert integer_log(3, 3) == (1, True)
assert integer_log(3*2, 3) == (1, False)
assert integer_log(3**2, 3) == (2, True)
assert integer_log(3*4, 3) == (2, False)
assert integer_log(3**3, 3) == (3, True)
assert integer_log(27, 5) == (2, False)
assert integer_log(2, 3) == (0, False)
assert integer_log(-4, -2) == (2, False)
assert integer_log(27, -3) == (3, False)
assert integer_log(-49, 7) == (0, False)
assert integer_log(-49, -7) == (2, False)
def test_isqrt():
from math import sqrt as _sqrt
limit = 17984395633462800708566937239551
assert int(_sqrt(limit)) == integer_nthroot(limit, 2)[0]
assert int(_sqrt(limit + 1)) != integer_nthroot(limit + 1, 2)[0]
assert isqrt(limit + 1) == integer_nthroot(limit + 1, 2)[0]
assert isqrt(limit + 1 + S.Half) == integer_nthroot(limit + 1, 2)[0]
def test_powers_Integer():
"""Test Integer._eval_power"""
# check infinity
assert S(1) ** S.Infinity == S.NaN
assert S(-1)** S.Infinity == S.NaN
assert S(2) ** S.Infinity == S.Infinity
assert S(-2)** S.Infinity == S.Infinity + S.Infinity * S.ImaginaryUnit
assert S(0) ** S.Infinity == 0
# check Nan
assert S(1) ** S.NaN == S.NaN
assert S(-1) ** S.NaN == S.NaN
# check for exact roots
assert S(-1) ** Rational(6, 5) == - (-1)**(S(1)/5)
assert sqrt(S(4)) == 2
assert sqrt(S(-4)) == I * 2
assert S(16) ** Rational(1, 4) == 2
assert S(-16) ** Rational(1, 4) == 2 * (-1)**Rational(1, 4)
assert S(9) ** Rational(3, 2) == 27
assert S(-9) ** Rational(3, 2) == -27*I
assert S(27) ** Rational(2, 3) == 9
assert S(-27) ** Rational(2, 3) == 9 * (S(-1) ** Rational(2, 3))
assert (-2) ** Rational(-2, 1) == Rational(1, 4)
# not exact roots
assert sqrt(-3) == I*sqrt(3)
assert (3) ** (S(3)/2) == 3 * sqrt(3)
assert (-3) ** (S(3)/2) == - 3 * sqrt(-3)
assert (-3) ** (S(5)/2) == 9 * I * sqrt(3)
assert (-3) ** (S(7)/2) == - I * 27 * sqrt(3)
assert (2) ** (S(3)/2) == 2 * sqrt(2)
assert (2) ** (S(-3)/2) == sqrt(2) / 4
assert (81) ** (S(2)/3) == 9 * (S(3) ** (S(2)/3))
assert (-81) ** (S(2)/3) == 9 * (S(-3) ** (S(2)/3))
assert (-3) ** Rational(-7, 3) == \
-(-1)**Rational(2, 3)*3**Rational(2, 3)/27
assert (-3) ** Rational(-2, 3) == \
-(-1)**Rational(1, 3)*3**Rational(1, 3)/3
# join roots
assert sqrt(6) + sqrt(24) == 3*sqrt(6)
assert sqrt(2) * sqrt(3) == sqrt(6)
# separate symbols & constansts
x = Symbol("x")
assert sqrt(49 * x) == 7 * sqrt(x)
assert sqrt((3 - sqrt(pi)) ** 2) == 3 - sqrt(pi)
# check that it is fast for big numbers
assert (2**64 + 1) ** Rational(4, 3)
assert (2**64 + 1) ** Rational(17, 25)
# negative rational power and negative base
assert (-3) ** Rational(-7, 3) == \
-(-1)**Rational(2, 3)*3**Rational(2, 3)/27
assert (-3) ** Rational(-2, 3) == \
-(-1)**Rational(1, 3)*3**Rational(1, 3)/3
assert (-2) ** Rational(-10, 3) == \
(-1)**Rational(2, 3)*2**Rational(2, 3)/16
assert abs(Pow(-2, Rational(-10, 3)).n() -
Pow(-2, Rational(-10, 3), evaluate=False).n()) < 1e-16
# negative base and rational power with some simplification
assert (-8) ** Rational(2, 5) == \
2*(-1)**Rational(2, 5)*2**Rational(1, 5)
assert (-4) ** Rational(9, 5) == \
-8*(-1)**Rational(4, 5)*2**Rational(3, 5)
assert S(1234).factors() == {617: 1, 2: 1}
assert Rational(2*3, 3*5*7).factors() == {2: 1, 5: -1, 7: -1}
# test that eval_power factors numbers bigger than
# the current limit in factor_trial_division (2**15)
from sympy import nextprime
n = nextprime(2**15)
assert sqrt(n**2) == n
assert sqrt(n**3) == n*sqrt(n)
assert sqrt(4*n) == 2*sqrt(n)
# check that factors of base with powers sharing gcd with power are removed
assert (2**4*3)**Rational(1, 6) == 2**Rational(2, 3)*3**Rational(1, 6)
assert (2**4*3)**Rational(5, 6) == 8*2**Rational(1, 3)*3**Rational(5, 6)
# check that bases sharing a gcd are exptracted
assert 2**Rational(1, 3)*3**Rational(1, 4)*6**Rational(1, 5) == \
2**Rational(8, 15)*3**Rational(9, 20)
assert sqrt(8)*24**Rational(1, 3)*6**Rational(1, 5) == \
4*2**Rational(7, 10)*3**Rational(8, 15)
assert sqrt(8)*(-24)**Rational(1, 3)*(-6)**Rational(1, 5) == \
4*(-3)**Rational(8, 15)*2**Rational(7, 10)
assert 2**Rational(1, 3)*2**Rational(8, 9) == 2*2**Rational(2, 9)
assert 2**Rational(2, 3)*6**Rational(1, 3) == 2*3**Rational(1, 3)
assert 2**Rational(2, 3)*6**Rational(8, 9) == \
2*2**Rational(5, 9)*3**Rational(8, 9)
assert (-2)**Rational(2, S(3))*(-4)**Rational(1, S(3)) == -2*2**Rational(1, 3)
assert 3*Pow(3, 2, evaluate=False) == 3**3
assert 3*Pow(3, -1/S(3), evaluate=False) == 3**(2/S(3))
assert (-2)**(1/S(3))*(-3)**(1/S(4))*(-5)**(5/S(6)) == \
-(-1)**Rational(5, 12)*2**Rational(1, 3)*3**Rational(1, 4) * \
5**Rational(5, 6)
assert Integer(-2)**Symbol('', even=True) == \
Integer(2)**Symbol('', even=True)
assert (-1)**Float(.5) == 1.0*I
def test_powers_Rational():
"""Test Rational._eval_power"""
# check infinity
assert Rational(1, 2) ** S.Infinity == 0
assert Rational(3, 2) ** S.Infinity == S.Infinity
assert Rational(-1, 2) ** S.Infinity == 0
assert Rational(-3, 2) ** S.Infinity == \
S.Infinity + S.Infinity * S.ImaginaryUnit
# check Nan
assert Rational(3, 4) ** S.NaN == S.NaN
assert Rational(-2, 3) ** S.NaN == S.NaN
# exact roots on numerator
assert sqrt(Rational(4, 3)) == 2 * sqrt(3) / 3
assert Rational(4, 3) ** Rational(3, 2) == 8 * sqrt(3) / 9
assert sqrt(Rational(-4, 3)) == I * 2 * sqrt(3) / 3
assert Rational(-4, 3) ** Rational(3, 2) == - I * 8 * sqrt(3) / 9
assert Rational(27, 2) ** Rational(1, 3) == 3 * (2 ** Rational(2, 3)) / 2
assert Rational(5**3, 8**3) ** Rational(4, 3) == Rational(5**4, 8**4)
# exact root on denominator
assert sqrt(Rational(1, 4)) == Rational(1, 2)
assert sqrt(Rational(1, -4)) == I * Rational(1, 2)
assert sqrt(Rational(3, 4)) == sqrt(3) / 2
assert sqrt(Rational(3, -4)) == I * sqrt(3) / 2
assert Rational(5, 27) ** Rational(1, 3) == (5 ** Rational(1, 3)) / 3
# not exact roots
assert sqrt(Rational(1, 2)) == sqrt(2) / 2
assert sqrt(Rational(-4, 7)) == I * sqrt(Rational(4, 7))
assert Rational(-3, 2)**Rational(-7, 3) == \
-4*(-1)**Rational(2, 3)*2**Rational(1, 3)*3**Rational(2, 3)/27
assert Rational(-3, 2)**Rational(-2, 3) == \
-(-1)**Rational(1, 3)*2**Rational(2, 3)*3**Rational(1, 3)/3
assert Rational(-3, 2)**Rational(-10, 3) == \
8*(-1)**Rational(2, 3)*2**Rational(1, 3)*3**Rational(2, 3)/81
assert abs(Pow(Rational(-2, 3), Rational(-7, 4)).n() -
Pow(Rational(-2, 3), Rational(-7, 4), evaluate=False).n()) < 1e-16
# negative integer power and negative rational base
assert Rational(-2, 3) ** Rational(-2, 1) == Rational(9, 4)
a = Rational(1, 10)
assert a**Float(a, 2) == Float(a, 2)**Float(a, 2)
assert Rational(-2, 3)**Symbol('', even=True) == \
Rational(2, 3)**Symbol('', even=True)
def test_powers_Float():
assert str((S('-1/10')**S('3/10')).n()) == str(Float(-.1)**(.3))
def test_abs1():
assert Rational(1, 6) != Rational(-1, 6)
assert abs(Rational(1, 6)) == abs(Rational(-1, 6))
def test_accept_int():
assert Float(4) == 4
def test_dont_accept_str():
assert Float("0.2") != "0.2"
assert not (Float("0.2") == "0.2")
def test_int():
a = Rational(5)
assert int(a) == 5
a = Rational(9, 10)
assert int(a) == int(-a) == 0
assert 1/(-1)**Rational(2, 3) == -(-1)**Rational(1, 3)
assert int(pi) == 3
assert int(E) == 2
assert int(GoldenRatio) == 1
assert int(TribonacciConstant) == 2
# issue 10368
a = S(32442016954)/78058255275
assert type(int(a)) is type(int(-a)) is int
def test_long():
a = Rational(5)
assert long(a) == 5
a = Rational(9, 10)
assert long(a) == long(-a) == 0
a = Integer(2**100)
assert long(a) == a
assert long(pi) == 3
assert long(E) == 2
assert long(GoldenRatio) == 1
assert long(TribonacciConstant) == 2
def test_real_bug():
x = Symbol("x")
assert str(2.0*x*x) in ["(2.0*x)*x", "2.0*x**2", "2.00000000000000*x**2"]
assert str(2.1*x*x) != "(2.0*x)*x"
def test_bug_sqrt():
assert ((sqrt(Rational(2)) + 1)*(sqrt(Rational(2)) - 1)).expand() == 1
def test_pi_Pi():
"Test that pi (instance) is imported, but Pi (class) is not"
from sympy import pi
with raises(ImportError):
from sympy import Pi
def test_no_len():
# there should be no len for numbers
raises(TypeError, lambda: len(Rational(2)))
raises(TypeError, lambda: len(Rational(2, 3)))
raises(TypeError, lambda: len(Integer(2)))
def test_issue_3321():
assert sqrt(Rational(1, 5)) == sqrt(Rational(1, 5))
assert 5 * sqrt(Rational(1, 5)) == sqrt(5)
def test_issue_3692():
assert ((-1)**Rational(1, 6)).expand(complex=True) == I/2 + sqrt(3)/2
assert ((-5)**Rational(1, 6)).expand(complex=True) == \
5**Rational(1, 6)*I/2 + 5**Rational(1, 6)*sqrt(3)/2
assert ((-64)**Rational(1, 6)).expand(complex=True) == I + sqrt(3)
def test_issue_3423():
x = Symbol("x")
assert sqrt(x - 1).as_base_exp() == (x - 1, S.Half)
assert sqrt(x - 1) != I*sqrt(1 - x)
def test_issue_3449():
x = Symbol("x")
assert sqrt(x - 1).subs(x, 5) == 2
def test_issue_13890():
x = Symbol("x")
e = (-x/4 - S(1)/12)**x - 1
f = simplify(e)
a = S(9)/5
assert abs(e.subs(x,a).evalf() - f.subs(x,a).evalf()) < 1e-15
def test_Integer_factors():
def F(i):
return Integer(i).factors()
assert F(1) == {}
assert F(2) == {2: 1}
assert F(3) == {3: 1}
assert F(4) == {2: 2}
assert F(5) == {5: 1}
assert F(6) == {2: 1, 3: 1}
assert F(7) == {7: 1}
assert F(8) == {2: 3}
assert F(9) == {3: 2}
assert F(10) == {2: 1, 5: 1}
assert F(11) == {11: 1}
assert F(12) == {2: 2, 3: 1}
assert F(13) == {13: 1}
assert F(14) == {2: 1, 7: 1}
assert F(15) == {3: 1, 5: 1}
assert F(16) == {2: 4}
assert F(17) == {17: 1}
assert F(18) == {2: 1, 3: 2}
assert F(19) == {19: 1}
assert F(20) == {2: 2, 5: 1}
assert F(21) == {3: 1, 7: 1}
assert F(22) == {2: 1, 11: 1}
assert F(23) == {23: 1}
assert F(24) == {2: 3, 3: 1}
assert F(25) == {5: 2}
assert F(26) == {2: 1, 13: 1}
assert F(27) == {3: 3}
assert F(28) == {2: 2, 7: 1}
assert F(29) == {29: 1}
assert F(30) == {2: 1, 3: 1, 5: 1}
assert F(31) == {31: 1}
assert F(32) == {2: 5}
assert F(33) == {3: 1, 11: 1}
assert F(34) == {2: 1, 17: 1}
assert F(35) == {5: 1, 7: 1}
assert F(36) == {2: 2, 3: 2}
assert F(37) == {37: 1}
assert F(38) == {2: 1, 19: 1}
assert F(39) == {3: 1, 13: 1}
assert F(40) == {2: 3, 5: 1}
assert F(41) == {41: 1}
assert F(42) == {2: 1, 3: 1, 7: 1}
assert F(43) == {43: 1}
assert F(44) == {2: 2, 11: 1}
assert F(45) == {3: 2, 5: 1}
assert F(46) == {2: 1, 23: 1}
assert F(47) == {47: 1}
assert F(48) == {2: 4, 3: 1}
assert F(49) == {7: 2}
assert F(50) == {2: 1, 5: 2}
assert F(51) == {3: 1, 17: 1}
def test_Rational_factors():
def F(p, q, visual=None):
return Rational(p, q).factors(visual=visual)
assert F(2, 3) == {2: 1, 3: -1}
assert F(2, 9) == {2: 1, 3: -2}
assert F(2, 15) == {2: 1, 3: -1, 5: -1}
assert F(6, 10) == {3: 1, 5: -1}
def test_issue_4107():
assert pi*(E + 10) + pi*(-E - 10) != 0
assert pi*(E + 10**10) + pi*(-E - 10**10) != 0
assert pi*(E + 10**20) + pi*(-E - 10**20) != 0
assert pi*(E + 10**80) + pi*(-E - 10**80) != 0
assert (pi*(E + 10) + pi*(-E - 10)).expand() == 0
assert (pi*(E + 10**10) + pi*(-E - 10**10)).expand() == 0
assert (pi*(E + 10**20) + pi*(-E - 10**20)).expand() == 0
assert (pi*(E + 10**80) + pi*(-E - 10**80)).expand() == 0
def test_IntegerInteger():
a = Integer(4)
b = Integer(a)
assert a == b
def test_Rational_gcd_lcm_cofactors():
assert Integer(4).gcd(2) == Integer(2)
assert Integer(4).lcm(2) == Integer(4)
assert Integer(4).gcd(Integer(2)) == Integer(2)
assert Integer(4).lcm(Integer(2)) == Integer(4)
a, b = 720**99911, 480**12342
assert Integer(a).lcm(b) == a*b/Integer(a).gcd(b)
assert Integer(4).gcd(3) == Integer(1)
assert Integer(4).lcm(3) == Integer(12)
assert Integer(4).gcd(Integer(3)) == Integer(1)
assert Integer(4).lcm(Integer(3)) == Integer(12)
assert Rational(4, 3).gcd(2) == Rational(2, 3)
assert Rational(4, 3).lcm(2) == Integer(4)
assert Rational(4, 3).gcd(Integer(2)) == Rational(2, 3)
assert Rational(4, 3).lcm(Integer(2)) == Integer(4)
assert Integer(4).gcd(Rational(2, 9)) == Rational(2, 9)
assert Integer(4).lcm(Rational(2, 9)) == Integer(4)
assert Rational(4, 3).gcd(Rational(2, 9)) == Rational(2, 9)
assert Rational(4, 3).lcm(Rational(2, 9)) == Rational(4, 3)
assert Rational(4, 5).gcd(Rational(2, 9)) == Rational(2, 45)
assert Rational(4, 5).lcm(Rational(2, 9)) == Integer(4)
assert Rational(5, 9).lcm(Rational(3, 7)) == Rational(Integer(5).lcm(3),Integer(9).gcd(7))
assert Integer(4).cofactors(2) == (Integer(2), Integer(2), Integer(1))
assert Integer(4).cofactors(Integer(2)) == \
(Integer(2), Integer(2), Integer(1))
assert Integer(4).gcd(Float(2.0)) == S.One
assert Integer(4).lcm(Float(2.0)) == Float(8.0)
assert Integer(4).cofactors(Float(2.0)) == (S.One, Integer(4), Float(2.0))
assert Rational(1, 2).gcd(Float(2.0)) == S.One
assert Rational(1, 2).lcm(Float(2.0)) == Float(1.0)
assert Rational(1, 2).cofactors(Float(2.0)) == \
(S.One, Rational(1, 2), Float(2.0))
def test_Float_gcd_lcm_cofactors():
assert Float(2.0).gcd(Integer(4)) == S.One
assert Float(2.0).lcm(Integer(4)) == Float(8.0)
assert Float(2.0).cofactors(Integer(4)) == (S.One, Float(2.0), Integer(4))
assert Float(2.0).gcd(Rational(1, 2)) == S.One
assert Float(2.0).lcm(Rational(1, 2)) == Float(1.0)
assert Float(2.0).cofactors(Rational(1, 2)) == \
(S.One, Float(2.0), Rational(1, 2))
def test_issue_4611():
assert abs(pi._evalf(50) - 3.14159265358979) < 1e-10
assert abs(E._evalf(50) - 2.71828182845905) < 1e-10
assert abs(Catalan._evalf(50) - 0.915965594177219) < 1e-10
assert abs(EulerGamma._evalf(50) - 0.577215664901533) < 1e-10
assert abs(GoldenRatio._evalf(50) - 1.61803398874989) < 1e-10
assert abs(TribonacciConstant._evalf(50) - 1.83928675521416) < 1e-10
x = Symbol("x")
assert (pi + x).evalf() == pi.evalf() + x
assert (E + x).evalf() == E.evalf() + x
assert (Catalan + x).evalf() == Catalan.evalf() + x
assert (EulerGamma + x).evalf() == EulerGamma.evalf() + x
assert (GoldenRatio + x).evalf() == GoldenRatio.evalf() + x
assert (TribonacciConstant + x).evalf() == TribonacciConstant.evalf() + x
@conserve_mpmath_dps
def test_conversion_to_mpmath():
assert mpmath.mpmathify(Integer(1)) == mpmath.mpf(1)
assert mpmath.mpmathify(Rational(1, 2)) == mpmath.mpf(0.5)
assert mpmath.mpmathify(Float('1.23', 15)) == mpmath.mpf('1.23')
assert mpmath.mpmathify(I) == mpmath.mpc(1j)
assert mpmath.mpmathify(1 + 2*I) == mpmath.mpc(1 + 2j)
assert mpmath.mpmathify(1.0 + 2*I) == mpmath.mpc(1 + 2j)
assert mpmath.mpmathify(1 + 2.0*I) == mpmath.mpc(1 + 2j)
assert mpmath.mpmathify(1.0 + 2.0*I) == mpmath.mpc(1 + 2j)
assert mpmath.mpmathify(Rational(1, 2) + Rational(1, 2)*I) == mpmath.mpc(0.5 + 0.5j)
assert mpmath.mpmathify(2*I) == mpmath.mpc(2j)
assert mpmath.mpmathify(2.0*I) == mpmath.mpc(2j)
assert mpmath.mpmathify(Rational(1, 2)*I) == mpmath.mpc(0.5j)
mpmath.mp.dps = 100
assert mpmath.mpmathify(pi.evalf(100) + pi.evalf(100)*I) == mpmath.pi + mpmath.pi*mpmath.j
assert mpmath.mpmathify(pi.evalf(100)*I) == mpmath.pi*mpmath.j
def test_relational():
# real
x = S(.1)
assert (x != cos) is True
assert (x == cos) is False
# rational
x = Rational(1, 3)
assert (x != cos) is True
assert (x == cos) is False
# integer defers to rational so these tests are omitted
# number symbol
x = pi
assert (x != cos) is True
assert (x == cos) is False
def test_Integer_as_index():
assert 'hello'[Integer(2):] == 'llo'
def test_Rational_int():
assert int( Rational(7, 5)) == 1
assert int( Rational(1, 2)) == 0
assert int(-Rational(1, 2)) == 0
assert int(-Rational(7, 5)) == -1
def test_zoo():
b = Symbol('b', finite=True)
nz = Symbol('nz', nonzero=True)
p = Symbol('p', positive=True)
n = Symbol('n', negative=True)
im = Symbol('i', imaginary=True)
c = Symbol('c', complex=True)
pb = Symbol('pb', positive=True, finite=True)
nb = Symbol('nb', negative=True, finite=True)
imb = Symbol('ib', imaginary=True, finite=True)
for i in [I, S.Infinity, S.NegativeInfinity, S.Zero, S.One, S.Pi, S.Half, S(3), log(3),
b, nz, p, n, im, pb, nb, imb, c]:
if i.is_finite and (i.is_real or i.is_imaginary):
assert i + zoo is zoo
assert i - zoo is zoo
assert zoo + i is zoo
assert zoo - i is zoo
elif i.is_finite is not False:
assert (i + zoo).is_Add
assert (i - zoo).is_Add
assert (zoo + i).is_Add
assert (zoo - i).is_Add
else:
assert (i + zoo) is S.NaN
assert (i - zoo) is S.NaN
assert (zoo + i) is S.NaN
assert (zoo - i) is S.NaN
if fuzzy_not(i.is_zero) and (i.is_real or i.is_imaginary):
assert i*zoo is zoo
assert zoo*i is zoo
elif i.is_zero:
assert i*zoo is S.NaN
assert zoo*i is S.NaN
else:
assert (i*zoo).is_Mul
assert (zoo*i).is_Mul
if fuzzy_not((1/i).is_zero) and (i.is_real or i.is_imaginary):
assert zoo/i is zoo
elif (1/i).is_zero:
assert zoo/i is S.NaN
elif i.is_zero:
assert zoo/i is zoo
else:
assert (zoo/i).is_Mul
assert (I*oo).is_Mul # allow directed infinity
assert zoo + zoo is S.NaN
assert zoo * zoo is zoo
assert zoo - zoo is S.NaN
assert zoo/zoo is S.NaN
assert zoo**zoo is S.NaN
assert zoo**0 is S.One
assert zoo**2 is zoo
assert 1/zoo is S.Zero
assert Mul.flatten([S(-1), oo, S(0)]) == ([S.NaN], [], None)
def test_issue_4122():
x = Symbol('x', nonpositive=True)
assert (oo + x).is_Add
x = Symbol('x', finite=True)
assert (oo + x).is_Add # x could be imaginary
x = Symbol('x', nonnegative=True)
assert oo + x == oo
x = Symbol('x', finite=True, real=True)
assert oo + x == oo
# similarly for negative infinity
x = Symbol('x', nonnegative=True)
assert (-oo + x).is_Add
x = Symbol('x', finite=True)
assert (-oo + x).is_Add
x = Symbol('x', nonpositive=True)
assert -oo + x == -oo
x = Symbol('x', finite=True, real=True)
assert -oo + x == -oo
def test_GoldenRatio_expand():
assert GoldenRatio.expand(func=True) == S.Half + sqrt(5)/2
def test_TribonacciConstant_expand():
assert TribonacciConstant.expand(func=True) == \
(1 + cbrt(19 - 3*sqrt(33)) + cbrt(19 + 3*sqrt(33))) / 3
def test_as_content_primitive():
assert S.Zero.as_content_primitive() == (1, 0)
assert S.Half.as_content_primitive() == (S.Half, 1)
assert (-S.Half).as_content_primitive() == (S.Half, -1)
assert S(3).as_content_primitive() == (3, 1)
assert S(3.1).as_content_primitive() == (1, 3.1)
def test_hashing_sympy_integers():
# Test for issue 5072
assert set([Integer(3)]) == set([int(3)])
assert hash(Integer(4)) == hash(int(4))
def test_issue_4172():
assert int((E**100).round()) == \
26881171418161354484126255515800135873611119
assert int((pi**100).round()) == \
51878483143196131920862615246303013562686760680406
assert int((Rational(1)/EulerGamma**100).round()) == \
734833795660954410469466
@XFAIL
def test_mpmath_issues():
from mpmath.libmp.libmpf import _normalize
import mpmath.libmp as mlib
rnd = mlib.round_nearest
mpf = (0, long(0), -123, -1, 53, rnd) # nan
assert _normalize(mpf, 53) != (0, long(0), 0, 0)
mpf = (0, long(0), -456, -2, 53, rnd) # +inf
assert _normalize(mpf, 53) != (0, long(0), 0, 0)
mpf = (1, long(0), -789, -3, 53, rnd) # -inf
assert _normalize(mpf, 53) != (0, long(0), 0, 0)
from mpmath.libmp.libmpf import fnan
assert mlib.mpf_eq(fnan, fnan)
def test_Catalan_EulerGamma_prec():
n = GoldenRatio
f = Float(n.n(), 5)
assert f._mpf_ == (0, long(212079), -17, 18)
assert f._prec == 20
assert n._as_mpf_val(20) == f._mpf_
n = EulerGamma
f = Float(n.n(), 5)
assert f._mpf_ == (0, long(302627), -19, 19)
assert f._prec == 20
assert n._as_mpf_val(20) == f._mpf_
def test_Float_eq():
assert Float(.12, 3) != Float(.12, 4)
assert Float(.12, 3) == .12
assert 0.12 == Float(.12, 3)
assert Float('.12', 22) != .12
def test_int_NumberSymbols():
assert [int(i) for i in [pi, EulerGamma, E, GoldenRatio, Catalan]] == \
[3, 0, 2, 1, 0]
def test_issue_6640():
from mpmath.libmp.libmpf import finf, fninf
# fnan is not included because Float no longer returns fnan,
# but otherwise, the same sort of test could apply
assert Float(finf).is_zero is False
assert Float(fninf).is_zero is False
assert bool(Float(0)) is False
def test_issue_6349():
assert Float('23.e3', '')._prec == 10
assert Float('23e3', '')._prec == 20
assert Float('23000', '')._prec == 20
assert Float('-23000', '')._prec == 20
def test_mpf_norm():
assert mpf_norm((1, 0, 1, 0), 10) == mpf('0')._mpf_
assert Float._new((1, 0, 1, 0), 10)._mpf_ == mpf('0')._mpf_
def test_latex():
assert latex(pi) == r"\pi"
assert latex(E) == r"e"
assert latex(GoldenRatio) == r"\phi"
assert latex(TribonacciConstant) == r"\mathrm{TribonacciConstant}"
assert latex(EulerGamma) == r"\gamma"
assert latex(oo) == r"\infty"
assert latex(-oo) == r"-\infty"
assert latex(zoo) == r"\tilde{\infty}"
assert latex(nan) == r"\mathrm{NaN}"
assert latex(I) == r"i"
def test_issue_7742():
assert -oo % 1 == nan
def test_simplify_AlgebraicNumber():
A = AlgebraicNumber
e = 3**(S(1)/6)*(3 + (135 + 78*sqrt(3))**(S(2)/3))/(45 + 26*sqrt(3))**(S(1)/3)
assert simplify(A(e)) == A(12) # wester test_C20
e = (41 + 29*sqrt(2))**(S(1)/5)
assert simplify(A(e)) == A(1 + sqrt(2)) # wester test_C21
e = (3 + 4*I)**(Rational(3, 2))
assert simplify(A(e)) == A(2 + 11*I) # issue 4401
def test_Float_idempotence():
x = Float('1.23', '')
y = Float(x)
z = Float(x, 15)
assert same_and_same_prec(y, x)
assert not same_and_same_prec(z, x)
x = Float(10**20)
y = Float(x)
z = Float(x, 15)
assert same_and_same_prec(y, x)
assert not same_and_same_prec(z, x)
def test_comp():
# sqrt(2) = 1.414213 5623730950...
a = sqrt(2).n(7)
assert comp(a, 1.41421346) is False
assert comp(a, 1.41421347)
assert comp(a, 1.41421366)
assert comp(a, 1.41421367) is False
assert comp(sqrt(2).n(2), '1.4')
assert comp(sqrt(2).n(2), Float(1.4, 2), '')
raises(ValueError, lambda: comp(sqrt(2).n(2), 1.4, ''))
assert comp(sqrt(2).n(2), Float(1.4, 3), '') is False
def test_issue_9491():
assert oo**zoo == nan
def test_issue_10063():
assert 2**Float(3) == Float(8)
def test_issue_10020():
assert oo**I is S.NaN
assert oo**(1 + I) is S.ComplexInfinity
assert oo**(-1 + I) is S.Zero
assert (-oo)**I is S.NaN
assert (-oo)**(-1 + I) is S.Zero
assert oo**t == Pow(oo, t, evaluate=False)
assert (-oo)**t == Pow(-oo, t, evaluate=False)
def test_invert_numbers():
assert S(2).invert(5) == 3
assert S(2).invert(S(5)/2) == S.Half
assert S(2).invert(5.) == 3
assert S(2).invert(S(5)) == 3
assert S(2.).invert(5) == 3
assert S(sqrt(2)).invert(5) == 1/sqrt(2)
assert S(sqrt(2)).invert(sqrt(3)) == 1/sqrt(2)
def test_mod_inverse():
assert mod_inverse(3, 11) == 4
assert mod_inverse(5, 11) == 9
assert mod_inverse(21124921, 521512) == 7713
assert mod_inverse(124215421, 5125) == 2981
assert mod_inverse(214, 12515) == 1579
assert mod_inverse(5823991, 3299) == 1442
assert mod_inverse(123, 44) == 39
assert mod_inverse(2, 5) == 3
assert mod_inverse(-2, 5) == 2
assert mod_inverse(2, -5) == -2
assert mod_inverse(-2, -5) == -3
assert mod_inverse(-3, -7) == -5
x = Symbol('x')
assert S(2).invert(x) == S.Half
raises(TypeError, lambda: mod_inverse(2, x))
raises(ValueError, lambda: mod_inverse(2, S.Half))
raises(ValueError, lambda: mod_inverse(2, cos(1)**2 + sin(1)**2))
def test_golden_ratio_rewrite_as_sqrt():
assert GoldenRatio.rewrite(sqrt) == S.Half + sqrt(5)*S.Half
def test_tribonacci_constant_rewrite_as_sqrt():
assert TribonacciConstant.rewrite(sqrt) == \
(1 + cbrt(19 - 3*sqrt(33)) + cbrt(19 + 3*sqrt(33))) / 3
def test_comparisons_with_unknown_type():
class Foo(object):
"""
Class that is unaware of Basic, and relies on both classes returning
the NotImplemented singleton for equivalence to evaluate to False.
"""
ni, nf, nr = Integer(3), Float(1.0), Rational(1, 3)
foo = Foo()
for n in ni, nf, nr, oo, -oo, zoo, nan:
assert n != foo
assert foo != n
assert not n == foo
assert not foo == n
raises(TypeError, lambda: n < foo)
raises(TypeError, lambda: foo > n)
raises(TypeError, lambda: n > foo)
raises(TypeError, lambda: foo < n)
raises(TypeError, lambda: n <= foo)
raises(TypeError, lambda: foo >= n)
raises(TypeError, lambda: n >= foo)
raises(TypeError, lambda: foo <= n)
class Bar(object):
"""
Class that considers itself equal to any instance of Number except
infinities and nans, and relies on sympy types returning the
NotImplemented singleton for symmetric equality relations.
"""
def __eq__(self, other):
if other in (oo, -oo, zoo, nan):
return False
if isinstance(other, Number):
return True
return NotImplemented
def __ne__(self, other):
return not self == other
bar = Bar()
for n in ni, nf, nr:
assert n == bar
assert bar == n
assert not n != bar
assert not bar != n
for n in oo, -oo, zoo, nan:
assert n != bar
assert bar != n
assert not n == bar
assert not bar == n
for n in ni, nf, nr, oo, -oo, zoo, nan:
raises(TypeError, lambda: n < bar)
raises(TypeError, lambda: bar > n)
raises(TypeError, lambda: n > bar)
raises(TypeError, lambda: bar < n)
raises(TypeError, lambda: n <= bar)
raises(TypeError, lambda: bar >= n)
raises(TypeError, lambda: n >= bar)
raises(TypeError, lambda: bar <= n)
def test_NumberSymbol_comparison():
rpi = Rational('905502432259640373/288230376151711744')
fpi = Float(float(pi))
assert (rpi == pi) == (pi == rpi)
assert (rpi != pi) == (pi != rpi)
assert (rpi < pi) == (pi > rpi)
assert (rpi <= pi) == (pi >= rpi)
assert (rpi > pi) == (pi < rpi)
assert (rpi >= pi) == (pi <= rpi)
assert (fpi == pi) == (pi == fpi)
assert (fpi != pi) == (pi != fpi)
assert (fpi < pi) == (pi > fpi)
assert (fpi <= pi) == (pi >= fpi)
assert (fpi > pi) == (pi < fpi)
assert (fpi >= pi) == (pi <= fpi)
def test_Integer_precision():
# Make sure Integer inputs for keyword args work
assert Float('1.0', dps=Integer(15))._prec == 53
assert Float('1.0', precision=Integer(15))._prec == 15
assert type(Float('1.0', precision=Integer(15))._prec) == int
assert sympify(srepr(Float('1.0', precision=15))) == Float('1.0', precision=15)
def test_numpy_to_float():
from sympy.utilities.pytest import skip
from sympy.external import import_module
np = import_module('numpy')
if not np:
skip('numpy not installed. Abort numpy tests.')
def check_prec_and_relerr(npval, ratval):
prec = np.finfo(npval).nmant + 1
x = Float(npval)
assert x._prec == prec
y = Float(ratval, precision=prec)
assert abs((x - y)/y) < 2**(-(prec + 1))
check_prec_and_relerr(np.float16(2/3), S(2)/3)
check_prec_and_relerr(np.float32(2/3), S(2)/3)
check_prec_and_relerr(np.float64(2/3), S(2)/3)
# extended precision, on some arch/compilers:
x = np.longdouble(2)/3
check_prec_and_relerr(x, S(2)/3)
y = Float(x, precision=10)
assert same_and_same_prec(y, Float(S(2)/3, precision=10))
raises(TypeError, lambda: Float(np.complex64(1+2j)))
raises(TypeError, lambda: Float(np.complex128(1+2j)))
def test_Integer_ceiling_floor():
a = Integer(4)
assert(a.floor() == a)
assert(a.ceiling() == a)
def test_ComplexInfinity():
assert((zoo).floor() == zoo)
assert((zoo).ceiling() == zoo)
assert(zoo**zoo == S.NaN)
def test_Infinity_floor_ceiling_power():
assert((oo).floor() == oo)
assert((oo).ceiling() == oo)
assert((oo)**S.NaN == S.NaN)
assert((oo)**zoo == S.NaN)
def test_One_power():
assert((S.One)**12 == S.One)
assert((S.NegativeOne)**S.NaN == S.NaN)
def test_NegativeInfinity():
assert((-oo).floor() == -oo)
assert((-oo).ceiling() == -oo)
assert((-oo)**11 == -oo)
assert((-oo)**12 == oo)
|
f318b06d4847369198b13125fcb3bc0e2b23e268536d941712a3c48b3d8bb446
|
from sympy import (Lambda, Symbol, Function, Derivative, Subs, sqrt,
log, exp, Rational, Float, sin, cos, acos, diff, I, re, im,
E, expand, pi, O, Sum, S, polygamma, loggamma, expint,
Tuple, Dummy, Eq, Expr, symbols, nfloat, Piecewise, Indexed,
Matrix, Basic)
from sympy.utilities.pytest import XFAIL, raises
from sympy.core.basic import _aresame
from sympy.core.function import PoleError, _mexpand
from sympy.core.sympify import sympify
from sympy.sets.sets import FiniteSet
from sympy.solvers.solveset import solveset
from sympy.utilities.iterables import subsets, variations
from sympy.core.cache import clear_cache
from sympy.core.compatibility import range
from sympy.tensor.array import NDimArray
from sympy.abc import t, w, x, y, z
f, g, h = symbols('f g h', cls=Function)
_xi_1, _xi_2, _xi_3 = [Dummy() for i in range(3)]
def test_f_expand_complex():
x = Symbol('x', real=True)
assert f(x).expand(complex=True) == I*im(f(x)) + re(f(x))
assert exp(x).expand(complex=True) == exp(x)
assert exp(I*x).expand(complex=True) == cos(x) + I*sin(x)
assert exp(z).expand(complex=True) == cos(im(z))*exp(re(z)) + \
I*sin(im(z))*exp(re(z))
def test_bug1():
e = sqrt(-log(w))
assert e.subs(log(w), -x) == sqrt(x)
e = sqrt(-5*log(w))
assert e.subs(log(w), -x) == sqrt(5*x)
def test_general_function():
nu = Function('nu')
e = nu(x)
edx = e.diff(x)
edy = e.diff(y)
edxdx = e.diff(x).diff(x)
edxdy = e.diff(x).diff(y)
assert e == nu(x)
assert edx != nu(x)
assert edx == diff(nu(x), x)
assert edy == 0
assert edxdx == diff(diff(nu(x), x), x)
assert edxdy == 0
def test_general_function_nullary():
nu = Function('nu')
e = nu()
edx = e.diff(x)
edxdx = e.diff(x).diff(x)
assert e == nu()
assert edx != nu()
assert edx == 0
assert edxdx == 0
def test_derivative_subs_bug():
e = diff(g(x), x)
assert e.subs(g(x), f(x)) != e
assert e.subs(g(x), f(x)) == Derivative(f(x), x)
assert e.subs(g(x), -f(x)) == Derivative(-f(x), x)
assert e.subs(x, y) == Derivative(g(y), y)
def test_derivative_subs_self_bug():
d = diff(f(x), x)
assert d.subs(d, y) == y
def test_derivative_linearity():
assert diff(-f(x), x) == -diff(f(x), x)
assert diff(8*f(x), x) == 8*diff(f(x), x)
assert diff(8*f(x), x) != 7*diff(f(x), x)
assert diff(8*f(x)*x, x) == 8*f(x) + 8*x*diff(f(x), x)
assert diff(8*f(x)*y*x, x).expand() == 8*y*f(x) + 8*y*x*diff(f(x), x)
def test_derivative_evaluate():
assert Derivative(sin(x), x) != diff(sin(x), x)
assert Derivative(sin(x), x).doit() == diff(sin(x), x)
assert Derivative(Derivative(f(x), x), x) == diff(f(x), x, x)
assert Derivative(sin(x), x, 0) == sin(x)
assert Derivative(sin(x), (x, y), (x, -y)) == sin(x)
def test_diff_symbols():
assert diff(f(x, y, z), x, y, z) == Derivative(f(x, y, z), x, y, z)
assert diff(f(x, y, z), x, x, x) == Derivative(f(x, y, z), x, x, x) == Derivative(f(x, y, z), (x, 3))
assert diff(f(x, y, z), x, 3) == Derivative(f(x, y, z), x, 3)
# issue 5028
assert [diff(-z + x/y, sym) for sym in (z, x, y)] == [-1, 1/y, -x/y**2]
assert diff(f(x, y, z), x, y, z, 2) == Derivative(f(x, y, z), x, y, z, z)
assert diff(f(x, y, z), x, y, z, 2, evaluate=False) == \
Derivative(f(x, y, z), x, y, z, z)
assert Derivative(f(x, y, z), x, y, z)._eval_derivative(z) == \
Derivative(f(x, y, z), x, y, z, z)
assert Derivative(Derivative(f(x, y, z), x), y)._eval_derivative(z) == \
Derivative(f(x, y, z), x, y, z)
raises(TypeError, lambda: cos(x).diff((x, y)).variables)
assert cos(x).diff((x, y))._wrt_variables == [x]
def test_Function():
class myfunc(Function):
@classmethod
def eval(cls): # zero args
return
assert myfunc.nargs == FiniteSet(0)
assert myfunc().nargs == FiniteSet(0)
raises(TypeError, lambda: myfunc(x).nargs)
class myfunc(Function):
@classmethod
def eval(cls, x): # one arg
return
assert myfunc.nargs == FiniteSet(1)
assert myfunc(x).nargs == FiniteSet(1)
raises(TypeError, lambda: myfunc(x, y).nargs)
class myfunc(Function):
@classmethod
def eval(cls, *x): # star args
return
assert myfunc.nargs == S.Naturals0
assert myfunc(x).nargs == S.Naturals0
def test_nargs():
f = Function('f')
assert f.nargs == S.Naturals0
assert f(1).nargs == S.Naturals0
assert Function('f', nargs=2)(1, 2).nargs == FiniteSet(2)
assert sin.nargs == FiniteSet(1)
assert sin(2).nargs == FiniteSet(1)
assert log.nargs == FiniteSet(1, 2)
assert log(2).nargs == FiniteSet(1, 2)
assert Function('f', nargs=2).nargs == FiniteSet(2)
assert Function('f', nargs=0).nargs == FiniteSet(0)
assert Function('f', nargs=(0, 1)).nargs == FiniteSet(0, 1)
assert Function('f', nargs=None).nargs == S.Naturals0
raises(ValueError, lambda: Function('f', nargs=()))
def test_Lambda():
e = Lambda(x, x**2)
assert e(4) == 16
assert e(x) == x**2
assert e(y) == y**2
assert Lambda((), 42)() == 42
assert Lambda((), 42) == Lambda((), 42)
assert Lambda((), 42) != Lambda((), 43)
assert Lambda((), f(x))() == f(x)
assert Lambda((), 42).nargs == FiniteSet(0)
assert Lambda(x, x**2) == Lambda(x, x**2)
assert Lambda(x, x**2) == Lambda(y, y**2)
assert Lambda(x, x**2) != Lambda(y, y**2 + 1)
assert Lambda((x, y), x**y) == Lambda((y, x), y**x)
assert Lambda((x, y), x**y) != Lambda((x, y), y**x)
assert Lambda((x, y), x**y)(x, y) == x**y
assert Lambda((x, y), x**y)(3, 3) == 3**3
assert Lambda((x, y), x**y)(x, 3) == x**3
assert Lambda((x, y), x**y)(3, y) == 3**y
assert Lambda(x, f(x))(x) == f(x)
assert Lambda(x, x**2)(e(x)) == x**4
assert e(e(x)) == x**4
x1, x2 = (Indexed('x', i) for i in (1, 2))
assert Lambda((x1, x2), x1 + x2)(x, y) == x + y
assert Lambda((x, y), x + y).nargs == FiniteSet(2)
p = x, y, z, t
assert Lambda(p, t*(x + y + z))(*p) == t * (x + y + z)
assert Lambda(x, 2*x) + Lambda(y, 2*y) == 2*Lambda(x, 2*x)
assert Lambda(x, 2*x) not in [ Lambda(x, x) ]
raises(TypeError, lambda: Lambda(1, x))
assert Lambda(x, 1)(1) is S.One
def test_IdentityFunction():
assert Lambda(x, x) is Lambda(y, y) is S.IdentityFunction
assert Lambda(x, 2*x) is not S.IdentityFunction
assert Lambda((x, y), x) is not S.IdentityFunction
def test_Lambda_symbols():
assert Lambda(x, 2*x).free_symbols == set()
assert Lambda(x, x*y).free_symbols == {y}
assert Lambda((), 42).free_symbols == set()
assert Lambda((), x*y).free_symbols == {x,y}
def test_functionclas_symbols():
assert f.free_symbols == set()
def test_Lambda_arguments():
raises(TypeError, lambda: Lambda(x, 2*x)(x, y))
raises(TypeError, lambda: Lambda((x, y), x + y)(x))
raises(TypeError, lambda: Lambda((), 42)(x))
def test_Lambda_equality():
assert Lambda(x, 2*x) == Lambda(y, 2*y)
# although variables are casts as Dummies, the expressions
# should still compare equal
assert Lambda((x, y), 2*x) == Lambda((x, y), 2*x)
assert Lambda(x, 2*x) != Lambda((x, y), 2*x)
assert Lambda(x, 2*x) != 2*x
def test_Subs():
assert Subs(1, (), ()) is S.One
# check null subs influence on hashing
assert Subs(x, y, z) != Subs(x, y, 1)
# neutral subs works
assert Subs(x, x, 1).subs(x, y).has(y)
# self mapping var/point
assert Subs(Derivative(f(x), (x, 2)), x, x).doit() == f(x).diff(x, x)
assert Subs(x, x, 0).has(x) # it's a structural answer
assert not Subs(x, x, 0).free_symbols
assert Subs(Subs(x + y, x, 2), y, 1) == Subs(x + y, (x, y), (2, 1))
assert Subs(x, (x,), (0,)) == Subs(x, x, 0)
assert Subs(x, x, 0) == Subs(y, y, 0)
assert Subs(x, x, 0).subs(x, 1) == Subs(x, x, 0)
assert Subs(y, x, 0).subs(y, 1) == Subs(1, x, 0)
assert Subs(f(x), x, 0).doit() == f(0)
assert Subs(f(x**2), x**2, 0).doit() == f(0)
assert Subs(f(x, y, z), (x, y, z), (0, 1, 1)) != \
Subs(f(x, y, z), (x, y, z), (0, 0, 1))
assert Subs(x, y, 2).subs(x, y).doit() == 2
assert Subs(f(x, y), (x, y, z), (0, 1, 1)) != \
Subs(f(x, y) + z, (x, y, z), (0, 1, 0))
assert Subs(f(x, y), (x, y), (0, 1)).doit() == f(0, 1)
assert Subs(Subs(f(x, y), x, 0), y, 1).doit() == f(0, 1)
raises(ValueError, lambda: Subs(f(x, y), (x, y), (0, 0, 1)))
raises(ValueError, lambda: Subs(f(x, y), (x, x, y), (0, 0, 1)))
assert len(Subs(f(x, y), (x, y), (0, 1)).variables) == 2
assert Subs(f(x, y), (x, y), (0, 1)).point == Tuple(0, 1)
assert Subs(f(x), x, 0) == Subs(f(y), y, 0)
assert Subs(f(x, y), (x, y), (0, 1)) == Subs(f(x, y), (y, x), (1, 0))
assert Subs(f(x)*y, (x, y), (0, 1)) == Subs(f(y)*x, (y, x), (0, 1))
assert Subs(f(x)*y, (x, y), (1, 1)) == Subs(f(y)*x, (x, y), (1, 1))
assert Subs(f(x), x, 0).subs(x, 1).doit() == f(0)
assert Subs(f(x), x, y).subs(y, 0) == Subs(f(x), x, 0)
assert Subs(y*f(x), x, y).subs(y, 2) == Subs(2*f(x), x, 2)
assert (2 * Subs(f(x), x, 0)).subs(Subs(f(x), x, 0), y) == 2*y
assert Subs(f(x), x, 0).free_symbols == set([])
assert Subs(f(x, y), x, z).free_symbols == {y, z}
assert Subs(f(x).diff(x), x, 0).doit(), Subs(f(x).diff(x), x, 0)
assert Subs(1 + f(x).diff(x), x, 0).doit(), 1 + Subs(f(x).diff(x), x, 0)
assert Subs(y*f(x, y).diff(x), (x, y), (0, 2)).doit() == \
2*Subs(Derivative(f(x, 2), x), x, 0)
assert Subs(y**2*f(x), x, 0).diff(y) == 2*y*f(0)
e = Subs(y**2*f(x), x, y)
assert e.diff(y) == e.doit().diff(y) == y**2*Derivative(f(y), y) + 2*y*f(y)
assert Subs(f(x), x, 0) + Subs(f(x), x, 0) == 2*Subs(f(x), x, 0)
e1 = Subs(z*f(x), x, 1)
e2 = Subs(z*f(y), y, 1)
assert e1 + e2 == 2*e1
assert e1.__hash__() == e2.__hash__()
assert Subs(z*f(x + 1), x, 1) not in [ e1, e2 ]
assert Derivative(f(x), x).subs(x, g(x)) == Derivative(f(g(x)), g(x))
assert Derivative(f(x), x).subs(x, x + y) == Subs(Derivative(f(x), x),
x, x + y)
assert Subs(f(x)*cos(y) + z, (x, y), (0, pi/3)).n(2) == \
Subs(f(x)*cos(y) + z, (x, y), (0, pi/3)).evalf(2) == \
z + Rational('1/2').n(2)*f(0)
assert f(x).diff(x).subs(x, 0).subs(x, y) == f(x).diff(x).subs(x, 0)
assert (x*f(x).diff(x).subs(x, 0)).subs(x, y) == y*f(x).diff(x).subs(x, 0)
assert Subs(Derivative(g(x)**2, g(x), x), g(x), exp(x)
).doit() == 2*exp(x)
assert Subs(Derivative(g(x)**2, g(x), x), g(x), exp(x)
).doit(deep=False) == 2*Derivative(exp(x), x)
assert Derivative(f(x, g(x)), x).doit() == Derivative(g(x), x
)*Subs(Derivative(f(x, y), y), y, g(x)
) + Subs(Derivative(f(y, g(x)), y), y, x)
def test_doitdoit():
done = Derivative(f(x, g(x)), x, g(x)).doit()
assert done == done.doit()
@XFAIL
def test_Subs2():
# this reflects a limitation of subs(), probably won't fix
assert Subs(f(x), x**2, x).doit() == f(sqrt(x))
def test_expand_function():
assert expand(x + y) == x + y
assert expand(x + y, complex=True) == I*im(x) + I*im(y) + re(x) + re(y)
assert expand((x + y)**11, modulus=11) == x**11 + y**11
def test_function_comparable():
assert sin(x).is_comparable is False
assert cos(x).is_comparable is False
assert sin(Float('0.1')).is_comparable is True
assert cos(Float('0.1')).is_comparable is True
assert sin(E).is_comparable is True
assert cos(E).is_comparable is True
assert sin(Rational(1, 3)).is_comparable is True
assert cos(Rational(1, 3)).is_comparable is True
@XFAIL
def test_function_comparable_infinities():
assert sin(oo).is_comparable is False
assert sin(-oo).is_comparable is False
assert sin(zoo).is_comparable is False
assert sin(nan).is_comparable is False
def test_deriv1():
# These all requre derivatives evaluated at a point (issue 4719) to work.
# See issue 4624
assert f(2*x).diff(x) == 2*Subs(Derivative(f(x), x), x, 2*x)
assert (f(x)**3).diff(x) == 3*f(x)**2*f(x).diff(x)
assert (f(2*x)**3).diff(x) == 6*f(2*x)**2*Subs(
Derivative(f(x), x), x, 2*x)
assert f(2 + x).diff(x) == Subs(Derivative(f(x), x), x, x + 2)
assert f(2 + 3*x).diff(x) == 3*Subs(
Derivative(f(x), x), x, 3*x + 2)
assert f(3*sin(x)).diff(x) == 3*cos(x)*Subs(
Derivative(f(x), x), x, 3*sin(x))
# See issue 8510
assert f(x, x + z).diff(x) == (
Subs(Derivative(f(y, x + z), y), y, x) +
Subs(Derivative(f(x, y), y), y, x + z))
assert f(x, x**2).diff(x) == (
2*x*Subs(Derivative(f(x, y), y), y, x**2) +
Subs(Derivative(f(y, x**2), y), y, x))
# but Subs is not always necessary
assert f(x, g(y)).diff(g(y)) == Derivative(f(x, g(y)), g(y))
def test_deriv2():
assert (x**3).diff(x) == 3*x**2
assert (x**3).diff(x, evaluate=False) != 3*x**2
assert (x**3).diff(x, evaluate=False) == Derivative(x**3, x)
assert diff(x**3, x) == 3*x**2
assert diff(x**3, x, evaluate=False) != 3*x**2
assert diff(x**3, x, evaluate=False) == Derivative(x**3, x)
def test_func_deriv():
assert f(x).diff(x) == Derivative(f(x), x)
# issue 4534
assert f(x, y).diff(x, y) - f(x, y).diff(y, x) == 0
assert Derivative(f(x, y), x, y).args[1:] == ((x, 1), (y, 1))
assert Derivative(f(x, y), y, x).args[1:] == ((y, 1), (x, 1))
assert (Derivative(f(x, y), x, y) - Derivative(f(x, y), y, x)).doit() == 0
def test_suppressed_evaluation():
a = sin(0, evaluate=False)
assert a != 0
assert a.func is sin
assert a.args == (0,)
def test_function_evalf():
def eq(a, b, eps):
return abs(a - b) < eps
assert eq(sin(1).evalf(15), Float("0.841470984807897"), 1e-13)
assert eq(
sin(2).evalf(25), Float("0.9092974268256816953960199", 25), 1e-23)
assert eq(sin(1 + I).evalf(
15), Float("1.29845758141598") + Float("0.634963914784736")*I, 1e-13)
assert eq(exp(1 + I).evalf(15), Float(
"1.46869393991588") + Float("2.28735528717884239")*I, 1e-13)
assert eq(exp(-0.5 + 1.5*I).evalf(15), Float(
"0.0429042815937374") + Float("0.605011292285002")*I, 1e-13)
assert eq(log(pi + sqrt(2)*I).evalf(
15), Float("1.23699044022052") + Float("0.422985442737893")*I, 1e-13)
assert eq(cos(100).evalf(15), Float("0.86231887228768"), 1e-13)
def test_extensibility_eval():
class MyFunc(Function):
@classmethod
def eval(cls, *args):
return (0, 0, 0)
assert MyFunc(0) == (0, 0, 0)
def test_function_non_commutative():
x = Symbol('x', commutative=False)
assert f(x).is_commutative is False
assert sin(x).is_commutative is False
assert exp(x).is_commutative is False
assert log(x).is_commutative is False
assert f(x).is_complex is False
assert sin(x).is_complex is False
assert exp(x).is_complex is False
assert log(x).is_complex is False
def test_function_complex():
x = Symbol('x', complex=True)
assert f(x).is_commutative is True
assert sin(x).is_commutative is True
assert exp(x).is_commutative is True
assert log(x).is_commutative is True
assert f(x).is_complex is True
assert sin(x).is_complex is True
assert exp(x).is_complex is True
assert log(x).is_complex is True
def test_function__eval_nseries():
n = Symbol('n')
assert sin(x)._eval_nseries(x, 2, None) == x + O(x**2)
assert sin(x + 1)._eval_nseries(x, 2, None) == x*cos(1) + sin(1) + O(x**2)
assert sin(pi*(1 - x))._eval_nseries(x, 2, None) == pi*x + O(x**2)
assert acos(1 - x**2)._eval_nseries(x, 2, None) == sqrt(2)*sqrt(x**2) + O(x**2)
assert polygamma(n, x + 1)._eval_nseries(x, 2, None) == \
polygamma(n, 1) + polygamma(n + 1, 1)*x + O(x**2)
raises(PoleError, lambda: sin(1/x)._eval_nseries(x, 2, None))
assert acos(1 - x)._eval_nseries(x, 2, None) == sqrt(2)*sqrt(x) + O(x)
assert acos(1 + x)._eval_nseries(x, 2, None) == sqrt(2)*sqrt(-x) + O(x) # XXX: wrong, branch cuts
assert loggamma(1/x)._eval_nseries(x, 0, None) == \
log(x)/2 - log(x)/x - 1/x + O(1, x)
assert loggamma(log(1/x)).nseries(x, n=1, logx=y) == loggamma(-y)
# issue 6725:
assert expint(S(3)/2, -x)._eval_nseries(x, 5, None) == \
2 - 2*sqrt(pi)*sqrt(-x) - 2*x - x**2/3 - x**3/15 - x**4/84 + O(x**5)
assert sin(sqrt(x))._eval_nseries(x, 3, None) == \
sqrt(x) - x**(S(3)/2)/6 + x**(S(5)/2)/120 + O(x**3)
def test_doit():
n = Symbol('n', integer=True)
f = Sum(2 * n * x, (n, 1, 3))
d = Derivative(f, x)
assert d.doit() == 12
assert d.doit(deep=False) == Sum(2*n, (n, 1, 3))
def test_evalf_default():
from sympy.functions.special.gamma_functions import polygamma
assert type(sin(4.0)) == Float
assert type(re(sin(I + 1.0))) == Float
assert type(im(sin(I + 1.0))) == Float
assert type(sin(4)) == sin
assert type(polygamma(2.0, 4.0)) == Float
assert type(sin(Rational(1, 4))) == sin
def test_issue_5399():
args = [x, y, S(2), S.Half]
def ok(a):
"""Return True if the input args for diff are ok"""
if not a:
return False
if a[0].is_Symbol is False:
return False
s_at = [i for i in range(len(a)) if a[i].is_Symbol]
n_at = [i for i in range(len(a)) if not a[i].is_Symbol]
# every symbol is followed by symbol or int
# every number is followed by a symbol
return (all(a[i + 1].is_Symbol or a[i + 1].is_Integer
for i in s_at if i + 1 < len(a)) and
all(a[i + 1].is_Symbol
for i in n_at if i + 1 < len(a)))
eq = x**10*y**8
for a in subsets(args):
for v in variations(a, len(a)):
if ok(v):
noraise = eq.diff(*v)
else:
raises(ValueError, lambda: eq.diff(*v))
def test_derivative_numerically():
from random import random
z0 = random() + I*random()
assert abs(Derivative(sin(x), x).doit_numerically(z0) - cos(z0)) < 1e-15
def test_fdiff_argument_index_error():
from sympy.core.function import ArgumentIndexError
class myfunc(Function):
nargs = 1 # define since there is no eval routine
def fdiff(self, idx):
raise ArgumentIndexError
mf = myfunc(x)
assert mf.diff(x) == Derivative(mf, x)
raises(TypeError, lambda: myfunc(x, x))
def test_deriv_wrt_function():
x = f(t)
xd = diff(x, t)
xdd = diff(xd, t)
y = g(t)
yd = diff(y, t)
assert diff(x, t) == xd
assert diff(2 * x + 4, t) == 2 * xd
assert diff(2 * x + 4 + y, t) == 2 * xd + yd
assert diff(2 * x + 4 + y * x, t) == 2 * xd + x * yd + xd * y
assert diff(2 * x + 4 + y * x, x) == 2 + y
assert (diff(4 * x**2 + 3 * x + x * y, t) == 3 * xd + x * yd + xd * y +
8 * x * xd)
assert (diff(4 * x**2 + 3 * xd + x * y, t) == 3 * xdd + x * yd + xd * y +
8 * x * xd)
assert diff(4 * x**2 + 3 * xd + x * y, xd) == 3
assert diff(4 * x**2 + 3 * xd + x * y, xdd) == 0
assert diff(sin(x), t) == xd * cos(x)
assert diff(exp(x), t) == xd * exp(x)
assert diff(sqrt(x), t) == xd / (2 * sqrt(x))
def test_diff_wrt_value():
assert Expr()._diff_wrt is False
assert x._diff_wrt is True
assert f(x)._diff_wrt is True
assert Derivative(f(x), x)._diff_wrt is True
assert Derivative(x**2, x)._diff_wrt is False
def test_diff_wrt():
fx = f(x)
dfx = diff(f(x), x)
ddfx = diff(f(x), x, x)
assert diff(sin(fx) + fx**2, fx) == cos(fx) + 2*fx
assert diff(sin(dfx) + dfx**2, dfx) == cos(dfx) + 2*dfx
assert diff(sin(ddfx) + ddfx**2, ddfx) == cos(ddfx) + 2*ddfx
assert diff(fx**2, dfx) == 0
assert diff(fx**2, ddfx) == 0
assert diff(dfx**2, fx) == 0
assert diff(dfx**2, ddfx) == 0
assert diff(ddfx**2, dfx) == 0
assert diff(fx*dfx*ddfx, fx) == dfx*ddfx
assert diff(fx*dfx*ddfx, dfx) == fx*ddfx
assert diff(fx*dfx*ddfx, ddfx) == fx*dfx
assert diff(f(x), x).diff(f(x)) == 0
assert (sin(f(x)) - cos(diff(f(x), x))).diff(f(x)) == cos(f(x))
assert diff(sin(fx), fx, x) == diff(sin(fx), x, fx)
# Chain rule cases
assert f(g(x)).diff(x) == \
Derivative(g(x), x)*Derivative(f(g(x)), g(x))
assert diff(f(g(x), h(y)), x) == \
Derivative(g(x), x)*Derivative(f(g(x), h(y)), g(x))
assert diff(f(g(x), h(x)), x) == (
Subs(Derivative(f(y, h(x)), y), y, g(x))*Derivative(g(x), x) +
Subs(Derivative(f(g(x), y), y), y, h(x))*Derivative(h(x), x))
assert f(
sin(x)).diff(x) == cos(x)*Subs(Derivative(f(x), x), x, sin(x))
assert diff(f(g(x)), g(x)) == Derivative(f(g(x)), g(x))
def test_diff_wrt_func_subs():
assert f(g(x)).diff(x).subs(g, Lambda(x, 2*x)).doit() == f(2*x).diff(x)
def test_subs_in_derivative():
expr = sin(x*exp(y))
u = Function('u')
v = Function('v')
assert Derivative(expr, y).subs(expr, y) == Derivative(y, y)
assert Derivative(expr, y).subs(y, x).doit() == \
Derivative(expr, y).doit().subs(y, x)
assert Derivative(f(x, y), y).subs(y, x) == Subs(Derivative(f(x, y), y), y, x)
assert Derivative(f(x, y), y).subs(x, y) == Subs(Derivative(f(x, y), y), x, y)
assert Derivative(f(x, y), y).subs(y, g(x, y)) == Subs(Derivative(f(x, y), y), y, g(x, y)).doit()
assert Derivative(f(x, y), y).subs(x, g(x, y)) == Subs(Derivative(f(x, y), y), x, g(x, y))
assert Derivative(f(x, y), g(y)).subs(x, g(x, y)) == Derivative(f(g(x, y), y), g(y))
assert Derivative(f(u(x), h(y)), h(y)).subs(h(y), g(x, y)) == \
Subs(Derivative(f(u(x), h(y)), h(y)), h(y), g(x, y)).doit()
assert Derivative(f(x, y), y).subs(y, z) == Derivative(f(x, z), z)
assert Derivative(f(x, y), y).subs(y, g(y)) == Derivative(f(x, g(y)), g(y))
assert Derivative(f(g(x), h(y)), h(y)).subs(h(y), u(y)) == \
Derivative(f(g(x), u(y)), u(y))
assert Derivative(f(x, f(x, x)), f(x, x)).subs(
f, Lambda((x, y), x + y)) == Subs(
Derivative(z + x, z), z, 2*x)
assert Subs(Derivative(f(f(x)), x), f, cos).doit() == sin(x)*sin(cos(x))
assert Subs(Derivative(f(f(x)), f(x)), f, cos).doit() == -sin(cos(x))
# Issue 13791. No comparison (it's a long formula) but this used to raise an exception.
assert isinstance(v(x, y, u(x, y)).diff(y).diff(x).diff(y), Expr)
# This is also related to issues 13791 and 13795; issue 15190
F = Lambda((x, y), exp(2*x + 3*y))
abstract = f(x, f(x, x)).diff(x, 2)
concrete = F(x, F(x, x)).diff(x, 2)
assert (abstract.subs(f, F).doit() - concrete).simplify() == 0
# don't introduce a new symbol if not necessary
assert x in f(x).diff(x).subs(x, 0).atoms()
# case (4)
assert Derivative(f(x,f(x,y)), x, y).subs(x, g(y)
) == Subs(Derivative(f(x, f(x, y)), x, y), x, g(y))
assert Derivative(f(x, x), x).subs(x, 0
) == Subs(Derivative(f(x, x), x), x, 0)
# issue 15194
assert Derivative(f(y, g(x)), (x, z)).subs(z, x
) == Derivative(f(y, g(x)), (x, x))
df = f(x).diff(x)
assert df.subs(df, 1) is S.One
assert df.diff(df) is S.One
dxy = Derivative(f(x, y), x, y)
dyx = Derivative(f(x, y), y, x)
assert dxy.subs(Derivative(f(x, y), y, x), 1) is S.One
assert dxy.diff(dyx) is S.One
assert Derivative(f(x, y), x, 2, y, 3).subs(
dyx, g(x, y)) == Derivative(g(x, y), x, 1, y, 2)
assert Derivative(f(x, x - y), y).subs(x, x + y) == Subs(
Derivative(f(x, x - y), y), x, x + y)
def test_diff_wrt_not_allowed():
# issue 7027 included
for wrt in (
cos(x), re(x), x**2, x*y, 1 + x,
Derivative(cos(x), x), Derivative(f(f(x)), x)):
raises(ValueError, lambda: diff(f(x), wrt))
# if we don't differentiate wrt then don't raise error
assert diff(exp(x*y), x*y, 0) == exp(x*y)
def test_klein_gordon_lagrangian():
m = Symbol('m')
phi = f(x, t)
L = -(diff(phi, t)**2 - diff(phi, x)**2 - m**2*phi**2)/2
eqna = Eq(
diff(L, phi) - diff(L, diff(phi, x), x) - diff(L, diff(phi, t), t), 0)
eqnb = Eq(diff(phi, t, t) - diff(phi, x, x) + m**2*phi, 0)
assert eqna == eqnb
def test_sho_lagrangian():
m = Symbol('m')
k = Symbol('k')
x = f(t)
L = m*diff(x, t)**2/2 - k*x**2/2
eqna = Eq(diff(L, x), diff(L, diff(x, t), t))
eqnb = Eq(-k*x, m*diff(x, t, t))
assert eqna == eqnb
assert diff(L, x, t) == diff(L, t, x)
assert diff(L, diff(x, t), t) == m*diff(x, t, 2)
assert diff(L, t, diff(x, t)) == -k*x + m*diff(x, t, 2)
def test_straight_line():
F = f(x)
Fd = F.diff(x)
L = sqrt(1 + Fd**2)
assert diff(L, F) == 0
assert diff(L, Fd) == Fd/sqrt(1 + Fd**2)
def test_sort_variable():
vsort = Derivative._sort_variable_count
def vsort0(*v, **kw):
reverse = kw.get('reverse', False)
return [i[0] for i in vsort([(i, 0) for i in (
reversed(v) if reverse else v)])]
for R in range(2):
assert vsort0(y, x, reverse=R) == [x, y]
assert vsort0(f(x), x, reverse=R) == [x, f(x)]
assert vsort0(f(y), f(x), reverse=R) == [f(x), f(y)]
assert vsort0(g(x), f(y), reverse=R) == [f(y), g(x)]
assert vsort0(f(x, y), f(x), reverse=R) == [f(x), f(x, y)]
fx = f(x).diff(x)
assert vsort0(fx, y, reverse=R) == [y, fx]
fy = f(y).diff(y)
assert vsort0(fy, fx, reverse=R) == [fx, fy]
fxx = fx.diff(x)
assert vsort0(fxx, fx, reverse=R) == [fx, fxx]
assert vsort0(Basic(x), f(x), reverse=R) == [f(x), Basic(x)]
assert vsort0(Basic(y), Basic(x), reverse=R) == [Basic(x), Basic(y)]
assert vsort0(Basic(y, z), Basic(x), reverse=R) == [
Basic(x), Basic(y, z)]
assert vsort0(fx, x, reverse=R) == [
x, fx] if R else [fx, x]
assert vsort0(Basic(x), x, reverse=R) == [
x, Basic(x)] if R else [Basic(x), x]
assert vsort0(Basic(f(x)), f(x), reverse=R) == [
f(x), Basic(f(x))] if R else [Basic(f(x)), f(x)]
assert vsort0(Basic(x, z), Basic(x), reverse=R) == [
Basic(x), Basic(x, z)] if R else [Basic(x, z), Basic(x)]
assert vsort([]) == []
assert _aresame(vsort([(x, 1)]), [Tuple(x, 1)])
assert vsort([(x, y), (x, z)]) == [(x, y + z)]
assert vsort([(y, 1), (x, 1 + y)]) == [(x, 1 + y), (y, 1)]
# coverage complete; legacy tests below
assert vsort([(x, 3), (y, 2), (z, 1)]) == [(x, 3), (y, 2), (z, 1)]
assert vsort([(h(x), 1), (g(x), 1), (f(x), 1)]) == [
(f(x), 1), (g(x), 1), (h(x), 1)]
assert vsort([(z, 1), (y, 2), (x, 3), (h(x), 1), (g(x), 1),
(f(x), 1)]) == [(x, 3), (y, 2), (z, 1), (f(x), 1), (g(x), 1),
(h(x), 1)]
assert vsort([(x, 1), (f(x), 1), (y, 1), (f(y), 1)]) == [(x, 1),
(y, 1), (f(x), 1), (f(y), 1)]
assert vsort([(y, 1), (x, 2), (g(x), 1), (f(x), 1), (z, 1),
(h(x), 1), (y, 2), (x, 1)]) == [(x, 3), (y, 3), (z, 1),
(f(x), 1), (g(x), 1), (h(x), 1)]
assert vsort([(z, 1), (y, 1), (f(x), 1), (x, 1), (f(x), 1),
(g(x), 1)]) == [(x, 1), (y, 1), (z, 1), (f(x), 2), (g(x), 1)]
assert vsort([(z, 1), (y, 2), (f(x), 1), (x, 2), (f(x), 2),
(g(x), 1), (z, 2), (z, 1), (y, 1), (x, 1)]) == [(x, 3), (y, 3),
(z, 4), (f(x), 3), (g(x), 1)]
assert vsort(((y, 2), (x, 1), (y, 1), (x, 1))) == [(x, 2), (y, 3)]
assert isinstance(vsort([(x, 3), (y, 2), (z, 1)])[0], Tuple)
assert vsort([(x, 1), (f(x), 1), (x, 1)]) == [(x, 2), (f(x), 1)]
assert vsort([(y, 2), (x, 3), (z, 1)]) == [(x, 3), (y, 2), (z, 1)]
assert vsort([(h(y), 1), (g(x), 1), (f(x), 1)]) == [
(f(x), 1), (g(x), 1), (h(y), 1)]
assert vsort([(x, 1), (y, 1), (x, 1)]) == [(x, 2), (y, 1)]
assert vsort([(f(x), 1), (f(y), 1), (f(x), 1)]) == [
(f(x), 2), (f(y), 1)]
dfx = f(x).diff(x)
self = [(dfx, 1), (x, 1)]
assert vsort(self) == self
assert vsort([
(dfx, 1), (y, 1), (f(x), 1), (x, 1), (f(y), 1), (x, 1)]) == [
(y, 1), (f(x), 1), (f(y), 1), (dfx, 1), (x, 2)]
dfy = f(y).diff(y)
assert vsort([(dfy, 1), (dfx, 1)]) == [(dfx, 1), (dfy, 1)]
d2fx = dfx.diff(x)
assert vsort([(d2fx, 1), (dfx, 1)]) == [(dfx, 1), (d2fx, 1)]
def test_multiple_derivative():
# Issue #15007
assert f(x, y).diff(y, y, x, y, x
) == Derivative(f(x, y), (x, 2), (y, 3))
def test_unhandled():
class MyExpr(Expr):
def _eval_derivative(self, s):
if not s.name.startswith('xi'):
return self
else:
return None
d = Dummy()
eq = MyExpr(f(x), y, z)
assert diff(eq, x, y, f(x), z) == Derivative(eq, f(x))
assert diff(eq, f(x), x) == Derivative(eq, f(x))
assert f(x, y).diff(x,(y, z)) == Derivative(f(x, y), x, (y, z))
assert f(x, y).diff(x,(y, 0)) == Derivative(f(x, y), x)
def test_nfloat():
from sympy.core.basic import _aresame
from sympy.polys.rootoftools import rootof
x = Symbol("x")
eq = x**(S(4)/3) + 4*x**(S(1)/3)/3
assert _aresame(nfloat(eq), x**(S(4)/3) + (4.0/3)*x**(S(1)/3))
assert _aresame(nfloat(eq, exponent=True), x**(4.0/3) + (4.0/3)*x**(1.0/3))
eq = x**(S(4)/3) + 4*x**(x/3)/3
assert _aresame(nfloat(eq), x**(S(4)/3) + (4.0/3)*x**(x/3))
big = 12345678901234567890
# specify precision to match value used in nfloat
Float_big = Float(big, 15)
assert _aresame(nfloat(big), Float_big)
assert _aresame(nfloat(big*x), Float_big*x)
assert _aresame(nfloat(x**big, exponent=True), x**Float_big)
assert nfloat({x: sqrt(2)}) == {x: nfloat(sqrt(2))}
assert nfloat({sqrt(2): x}) == {sqrt(2): x}
assert nfloat(cos(x + sqrt(2))) == cos(x + nfloat(sqrt(2)))
# issue 6342
f = S('x*lamda + lamda**3*(x/2 + 1/2) + lamda**2 + 1/4')
assert not any(a.free_symbols for a in solveset(f.subs(x, -0.139)))
# issue 6632
assert nfloat(-100000*sqrt(2500000001) + 5000000001) == \
9.99999999800000e-11
# issue 7122
eq = cos(3*x**4 + y)*rootof(x**5 + 3*x**3 + 1, 0)
assert str(nfloat(eq, exponent=False, n=1)) == '-0.7*cos(3.0*x**4 + y)'
def test_issue_7068():
from sympy.abc import a, b
f = Function('f')
y1 = Dummy('y')
y2 = Dummy('y')
func1 = f(a + y1 * b)
func2 = f(a + y2 * b)
func1_y = func1.diff(y1)
func2_y = func2.diff(y2)
assert func1_y != func2_y
z1 = Subs(f(a), a, y1)
z2 = Subs(f(a), a, y2)
assert z1 != z2
def test_issue_7231():
from sympy.abc import a
ans1 = f(x).series(x, a)
res = (f(a) + (-a + x)*Subs(Derivative(f(y), y), y, a) +
(-a + x)**2*Subs(Derivative(f(y), y, y), y, a)/2 +
(-a + x)**3*Subs(Derivative(f(y), y, y, y),
y, a)/6 +
(-a + x)**4*Subs(Derivative(f(y), y, y, y, y),
y, a)/24 +
(-a + x)**5*Subs(Derivative(f(y), y, y, y, y, y),
y, a)/120 + O((-a + x)**6, (x, a)))
assert res == ans1
ans2 = f(x).series(x, a)
assert res == ans2
def test_issue_7687():
from sympy.core.function import Function
from sympy.abc import x
f = Function('f')(x)
ff = Function('f')(x)
match_with_cache = ff.matches(f)
assert isinstance(f, type(ff))
clear_cache()
ff = Function('f')(x)
assert isinstance(f, type(ff))
assert match_with_cache == ff.matches(f)
def test_issue_7688():
from sympy.core.function import Function, UndefinedFunction
f = Function('f') # actually an UndefinedFunction
clear_cache()
class A(UndefinedFunction):
pass
a = A('f')
assert isinstance(a, type(f))
def test_mexpand():
from sympy.abc import x
assert _mexpand(None) is None
assert _mexpand(1) is S.One
assert _mexpand(x*(x + 1)**2) == (x*(x + 1)**2).expand()
def test_issue_8469():
# This should not take forever to run
N = 40
def g(w, theta):
return 1/(1+exp(w-theta))
ws = symbols(['w%i'%i for i in range(N)])
import functools
expr = functools.reduce(g,ws)
def test_issue_12996():
# foo=True imitates the sort of arguments that Derivative can get
# from Integral when it passes doit to the expression
assert Derivative(im(x), x).doit(foo=True) == Derivative(im(x), x)
def test_should_evalf():
# This should not take forever to run (see #8506)
assert isinstance(sin((1.0 + 1.0*I)**10000 + 1), sin)
def test_Derivative_as_finite_difference():
# Central 1st derivative at gridpoint
x, h = symbols('x h', real=True)
dfdx = f(x).diff(x)
assert (dfdx.as_finite_difference([x-2, x-1, x, x+1, x+2]) -
(S(1)/12*(f(x-2)-f(x+2)) + S(2)/3*(f(x+1)-f(x-1)))).simplify() == 0
# Central 1st derivative "half-way"
assert (dfdx.as_finite_difference() -
(f(x + S(1)/2)-f(x - S(1)/2))).simplify() == 0
assert (dfdx.as_finite_difference(h) -
(f(x + h/S(2))-f(x - h/S(2)))/h).simplify() == 0
assert (dfdx.as_finite_difference([x - 3*h, x-h, x+h, x + 3*h]) -
(S(9)/(8*2*h)*(f(x+h) - f(x-h)) +
S(1)/(24*2*h)*(f(x - 3*h) - f(x + 3*h)))).simplify() == 0
# One sided 1st derivative at gridpoint
assert (dfdx.as_finite_difference([0, 1, 2], 0) -
(-S(3)/2*f(0) + 2*f(1) - f(2)/2)).simplify() == 0
assert (dfdx.as_finite_difference([x, x+h], x) -
(f(x+h) - f(x))/h).simplify() == 0
assert (dfdx.as_finite_difference([x-h, x, x+h], x-h) -
(-S(3)/(2*h)*f(x-h) + 2/h*f(x) -
S(1)/(2*h)*f(x+h))).simplify() == 0
# One sided 1st derivative "half-way"
assert (dfdx.as_finite_difference([x-h, x+h, x + 3*h, x + 5*h, x + 7*h])
- 1/(2*h)*(-S(11)/(12)*f(x-h) + S(17)/(24)*f(x+h)
+ S(3)/8*f(x + 3*h) - S(5)/24*f(x + 5*h)
+ S(1)/24*f(x + 7*h))).simplify() == 0
d2fdx2 = f(x).diff(x, 2)
# Central 2nd derivative at gridpoint
assert (d2fdx2.as_finite_difference([x-h, x, x+h]) -
h**-2 * (f(x-h) + f(x+h) - 2*f(x))).simplify() == 0
assert (d2fdx2.as_finite_difference([x - 2*h, x-h, x, x+h, x + 2*h]) -
h**-2 * (-S(1)/12*(f(x - 2*h) + f(x + 2*h)) +
S(4)/3*(f(x+h) + f(x-h)) - S(5)/2*f(x))).simplify() == 0
# Central 2nd derivative "half-way"
assert (d2fdx2.as_finite_difference([x - 3*h, x-h, x+h, x + 3*h]) -
(2*h)**-2 * (S(1)/2*(f(x - 3*h) + f(x + 3*h)) -
S(1)/2*(f(x+h) + f(x-h)))).simplify() == 0
# One sided 2nd derivative at gridpoint
assert (d2fdx2.as_finite_difference([x, x+h, x + 2*h, x + 3*h]) -
h**-2 * (2*f(x) - 5*f(x+h) +
4*f(x+2*h) - f(x+3*h))).simplify() == 0
# One sided 2nd derivative at "half-way"
assert (d2fdx2.as_finite_difference([x-h, x+h, x + 3*h, x + 5*h]) -
(2*h)**-2 * (S(3)/2*f(x-h) - S(7)/2*f(x+h) + S(5)/2*f(x + 3*h) -
S(1)/2*f(x + 5*h))).simplify() == 0
d3fdx3 = f(x).diff(x, 3)
# Central 3rd derivative at gridpoint
assert (d3fdx3.as_finite_difference() -
(-f(x - 3/S(2)) + 3*f(x - 1/S(2)) -
3*f(x + 1/S(2)) + f(x + 3/S(2)))).simplify() == 0
assert (d3fdx3.as_finite_difference(
[x - 3*h, x - 2*h, x-h, x, x+h, x + 2*h, x + 3*h]) -
h**-3 * (S(1)/8*(f(x - 3*h) - f(x + 3*h)) - f(x - 2*h) +
f(x + 2*h) + S(13)/8*(f(x-h) - f(x+h)))).simplify() == 0
# Central 3rd derivative at "half-way"
assert (d3fdx3.as_finite_difference([x - 3*h, x-h, x+h, x + 3*h]) -
(2*h)**-3 * (f(x + 3*h)-f(x - 3*h) +
3*(f(x-h)-f(x+h)))).simplify() == 0
# One sided 3rd derivative at gridpoint
assert (d3fdx3.as_finite_difference([x, x+h, x + 2*h, x + 3*h]) -
h**-3 * (f(x + 3*h)-f(x) + 3*(f(x+h)-f(x + 2*h)))).simplify() == 0
# One sided 3rd derivative at "half-way"
assert (d3fdx3.as_finite_difference([x-h, x+h, x + 3*h, x + 5*h]) -
(2*h)**-3 * (f(x + 5*h)-f(x-h) +
3*(f(x+h)-f(x + 3*h)))).simplify() == 0
# issue 11007
y = Symbol('y', real=True)
d2fdxdy = f(x, y).diff(x, y)
ref0 = Derivative(f(x + S(1)/2, y), y) - Derivative(f(x - S(1)/2, y), y)
assert (d2fdxdy.as_finite_difference(wrt=x) - ref0).simplify() == 0
half = S(1)/2
xm, xp, ym, yp = x-half, x+half, y-half, y+half
ref2 = f(xm, ym) + f(xp, yp) - f(xp, ym) - f(xm, yp)
assert (d2fdxdy.as_finite_difference() - ref2).simplify() == 0
def test_issue_11159():
# Tests Application._eval_subs
expr1 = E
expr0 = expr1 * expr1
expr1 = expr0.subs(expr1,expr0)
assert expr0 == expr1
def test_issue_12005():
e1 = Subs(Derivative(f(x), x), x, x)
assert e1.diff(x) == Derivative(f(x), x, x)
e2 = Subs(Derivative(f(x), x), x, x**2 + 1)
assert e2.diff(x) == 2*x*Subs(Derivative(f(x), x, x), x, x**2 + 1)
e3 = Subs(Derivative(f(x) + y**2 - y, y), y, y**2)
assert e3.diff(y) == 4*y
e4 = Subs(Derivative(f(x + y), y), y, (x**2))
assert e4.diff(y) == S.Zero
e5 = Subs(Derivative(f(x), x), (y, z), (y, z))
assert e5.diff(x) == Derivative(f(x), x, x)
assert f(g(x)).diff(g(x), g(x)) == Derivative(f(g(x)), g(x), g(x))
def test_issue_13843():
x = symbols('x')
f = Function('f')
m, n = symbols('m n', integer=True)
assert Derivative(Derivative(f(x), (x, m)), (x, n)) == Derivative(f(x), (x, m + n))
assert Derivative(Derivative(f(x), (x, m+5)), (x, n+3)) == Derivative(f(x), (x, m + n + 8))
assert Derivative(f(x), (x, n)).doit() == Derivative(f(x), (x, n))
def test_order_could_be_zero():
x, y = symbols('x, y')
n = symbols('n', integer=True, nonnegative=True)
m = symbols('m', integer=True, positive=True)
assert diff(y, (x, n)) == Piecewise((y, Eq(n, 0)), (0, True))
assert diff(y, (x, n + 1)) == S.Zero
assert diff(y, (x, m)) == S.Zero
def test_undefined_function_eq():
f = Function('f')
f2 = Function('f')
g = Function('g')
f_real = Function('f', is_real=True)
# This test may only be meaningful if the cache is turned off
assert f == f2
assert hash(f) == hash(f2)
assert f == f
assert f != g
assert f != f_real
def test_function_assumptions():
x = Symbol('x')
f = Function('f')
f_real = Function('f', real=True)
assert f != f_real
assert f(x) != f_real(x)
assert f(x).is_real is None
assert f_real(x).is_real is True
# Can also do it this way, but it won't be equal to f_real because of the
# way UndefinedFunction.__new__ works.
f_real2 = Function('f', is_real=True)
assert f_real2(x).is_real is True
def test_undef_fcn_float_issue_6938():
f = Function('ceil')
assert not f(0.3).is_number
f = Function('sin')
assert not f(0.3).is_number
assert not f(pi).evalf().is_number
x = Symbol('x')
assert not f(x).evalf(subs={x:1.2}).is_number
def test_undefined_function_eval():
# Issue 15170. Make sure UndefinedFunction with eval defined works
# properly. The issue there was that the hash was determined before _nargs
# was set, which is included in the hash, hence changing the hash. The
# class is added to sympy.core.core.all_classes before the hash is
# changed, meaning "temp in all_classes" would fail, causing sympify(temp(t))
# to give a new class. We will eventually remove all_classes, but make
# sure this continues to work.
fdiff = lambda self, argindex=1: cos(self.args[argindex - 1])
eval = classmethod(lambda cls, t: None)
_imp_ = classmethod(lambda cls, t: sin(t))
temp = Function('temp', fdiff=fdiff, eval=eval, _imp_=_imp_)
expr = temp(t)
assert sympify(expr) == expr
assert type(sympify(expr)).fdiff.__name__ == "<lambda>"
assert expr.diff(t) == cos(t)
def test_issue_15241():
F = f(x)
Fx = F.diff(x)
assert (F + x*Fx).diff(x, Fx) == 2
assert (F + x*Fx).diff(Fx, x) == 1
assert (x*F + x*Fx*F).diff(F, x) == x*Fx.diff(x) + Fx + 1
assert (x*F + x*Fx*F).diff(x, F) == x*Fx.diff(x) + Fx + 1
y = f(x)
G = f(y)
Gy = G.diff(y)
assert (G + y*Gy).diff(y, Gy) == 2
assert (G + y*Gy).diff(Gy, y) == 1
assert (y*G + y*Gy*G).diff(G, y) == y*Gy.diff(y) + Gy + 1
assert (y*G + y*Gy*G).diff(y, G) == y*Gy.diff(y) + Gy + 1
def test_issue_15266():
assert Subs(Derivative(f(y), x, y), y, g(x)).doit() != 0
def test_issue_7027():
for wrt in (cos(x), re(x), Derivative(cos(x), x)):
raises(ValueError, lambda: diff(f(x), wrt))
def test_derivative_quick_exit():
assert f(x).diff(y) == 0
assert f(x).diff(y, f(x)) == 0
assert f(x).diff(x, f(y)) == 0
assert f(f(x)).diff(x, f(x), f(y)) == 0
assert f(f(x)).diff(x, f(x), y) == 0
assert f(x).diff(g(x)) == 0
assert f(x).diff(x, f(x).diff(x)) == 1
df = f(x).diff(x)
assert f(x).diff(df) == 0
dg = g(x).diff(x)
assert dg.diff(df).doit() == 0
def test_issue_15084_13166():
eq = f(x, g(x))
assert eq.diff((g(x), y)) == Derivative(f(x, g(x)), (g(x), y))
# issue 13166
assert eq.diff(x, 2).doit() == (
(Derivative(f(x, g(x)), (g(x), 2))*Derivative(g(x), x) +
Subs(Derivative(f(x, _xi_2), _xi_2, x), _xi_2, g(x)))*Derivative(g(x),
x) + Derivative(f(x, g(x)), g(x))*Derivative(g(x), (x, 2)) +
Derivative(g(x), x)*Subs(Derivative(f(_xi_1, g(x)), _xi_1, g(x)),
_xi_1, x) + Subs(Derivative(f(_xi_1, g(x)), (_xi_1, 2)), _xi_1, x))
# issue 6681
assert diff(f(x, t, g(x, t)), x).doit() == (
Derivative(f(x, t, g(x, t)), g(x, t))*Derivative(g(x, t), x) +
Subs(Derivative(f(_xi_1, t, g(x, t)), _xi_1), _xi_1, x))
# make sure the order doesn't matter when using diff
assert eq.diff(x, g(x)) == eq.diff(g(x), x)
def test_negative_counts():
# issue 13873
raises(ValueError, lambda: sin(x).diff(x, -1))
def test_Derivative__new__():
raises(TypeError, lambda: f(x).diff((x, 2), 0))
assert f(x, y).diff([(x, y), 0]) == f(x, y)
assert f(x, y).diff([(x, y), 1]) == NDimArray([
Derivative(f(x, y), x), Derivative(f(x, y), y)])
assert f(x,y).diff(y, (x, z), y, x) == Derivative(
f(x, y), (x, z + 1), (y, 2))
assert Matrix([x]).diff(x, 2) == Matrix([0]) # is_zero exit
def test_issue_14719_10150():
class V(Expr):
_diff_wrt = True
is_scalar = False
assert V().diff(V()) == Derivative(V(), V())
assert (2*V()).diff(V()) == 2*Derivative(V(), V())
class X(Expr):
_diff_wrt = True
assert X().diff(X()) == 1
assert (2*X()).diff(X()) == 2
def test_noncommutative_issue_15131():
x = Symbol('x', commutative=False)
t = Symbol('t', commutative=False)
fx = Function('Fx', commutative=False)(x)
ft = Function('Ft', commutative=False)(t)
A = Symbol('A', commutative=False)
eq = fx * A * ft
eqdt = eq.diff(t)
assert eqdt.args[-1] == ft.diff(t)
def test_Subs_Derivative():
a = Derivative(f(g(x), h(x)), g(x), h(x),x)
b = Derivative(Derivative(f(g(x), h(x)), g(x), h(x)),x)
c = f(g(x), h(x)).diff(g(x), h(x), x)
d = f(g(x), h(x)).diff(g(x), h(x)).diff(x)
e = Derivative(f(g(x), h(x)), x)
eqs = (a, b, c, d, e)
subs = lambda arg: arg.subs(f, Lambda((x, y), exp(x + y))
).subs(g(x), 1/x).subs(h(x), x**3)
ans = 3*x**2*exp(1/x)*exp(x**3) - exp(1/x)*exp(x**3)/x**2
assert all(subs(i).doit().expand() == ans for i in eqs)
assert all(subs(i.doit()).doit().expand() == ans for i in eqs)
def test_issue_15360():
f = Function('f')
assert f.name == 'f'
|
27c8238c5aa0005e381d09bf9faa18f0b6f57b19ac5c7610ff616a55fd027740
|
"""This tests sympy/core/basic.py with (ideally) no reference to subclasses
of Basic or Atom."""
import collections
import sys
from sympy.core.basic import (Basic, Atom, preorder_traversal, as_Basic,
_atomic)
from sympy.core.singleton import S
from sympy.core.symbol import symbols
from sympy.core.function import Function, Lambda
from sympy.core.compatibility import default_sort_key
from sympy import sin, Q, cos, gamma, Tuple, Integral, Sum
from sympy.functions.elementary.exponential import exp
from sympy.utilities.pytest import raises
from sympy.core import I, pi
b1 = Basic()
b2 = Basic(b1)
b3 = Basic(b2)
b21 = Basic(b2, b1)
def test_structure():
assert b21.args == (b2, b1)
assert b21.func(*b21.args) == b21
assert bool(b1)
def test_equality():
instances = [b1, b2, b3, b21, Basic(b1, b1, b1), Basic]
for i, b_i in enumerate(instances):
for j, b_j in enumerate(instances):
assert (b_i == b_j) == (i == j)
assert (b_i != b_j) == (i != j)
assert Basic() != []
assert not(Basic() == [])
assert Basic() != 0
assert not(Basic() == 0)
class Foo(object):
"""
Class that is unaware of Basic, and relies on both classes returning
the NotImplemented singleton for equivalence to evaluate to False.
"""
b = Basic()
foo = Foo()
assert b != foo
assert foo != b
assert not b == foo
assert not foo == b
class Bar(object):
"""
Class that considers itself equal to any instance of Basic, and relies
on Basic returning the NotImplemented singleton in order to achieve
a symmetric equivalence relation.
"""
def __eq__(self, other):
if isinstance(other, Basic):
return True
return NotImplemented
def __ne__(self, other):
return not self == other
bar = Bar()
assert b == bar
assert bar == b
assert not b != bar
assert not bar != b
def test_matches_basic():
instances = [Basic(b1, b1, b2), Basic(b1, b2, b1), Basic(b2, b1, b1),
Basic(b1, b2), Basic(b2, b1), b2, b1]
for i, b_i in enumerate(instances):
for j, b_j in enumerate(instances):
if i == j:
assert b_i.matches(b_j) == {}
else:
assert b_i.matches(b_j) is None
assert b1.match(b1) == {}
def test_has():
assert b21.has(b1)
assert b21.has(b3, b1)
assert b21.has(Basic)
assert not b1.has(b21, b3)
assert not b21.has()
def test_subs():
assert b21.subs(b2, b1) == Basic(b1, b1)
assert b21.subs(b2, b21) == Basic(b21, b1)
assert b3.subs(b2, b1) == b2
assert b21.subs([(b2, b1), (b1, b2)]) == Basic(b2, b2)
assert b21.subs({b1: b2, b2: b1}) == Basic(b2, b2)
if sys.version_info >= (3, 4):
assert b21.subs(collections.ChainMap({b1: b2}, {b2: b1})) == Basic(b2, b2)
assert b21.subs(collections.OrderedDict([(b2, b1), (b1, b2)])) == Basic(b2, b2)
raises(ValueError, lambda: b21.subs('bad arg'))
raises(ValueError, lambda: b21.subs(b1, b2, b3))
# dict(b1=foo) creates a string 'b1' but leaves foo unchanged; subs
# will convert the first to a symbol but will raise an error if foo
# cannot be sympified; sympification is strict if foo is not string
raises(ValueError, lambda: b21.subs(b1='bad arg'))
def test_atoms():
assert b21.atoms() == set()
def test_free_symbols_empty():
assert b21.free_symbols == set()
def test_doit():
assert b21.doit() == b21
assert b21.doit(deep=False) == b21
def test_S():
assert repr(S) == 'S'
def test_xreplace():
assert b21.xreplace({b2: b1}) == Basic(b1, b1)
assert b21.xreplace({b2: b21}) == Basic(b21, b1)
assert b3.xreplace({b2: b1}) == b2
assert Basic(b1, b2).xreplace({b1: b2, b2: b1}) == Basic(b2, b1)
assert Atom(b1).xreplace({b1: b2}) == Atom(b1)
assert Atom(b1).xreplace({Atom(b1): b2}) == b2
raises(TypeError, lambda: b1.xreplace())
raises(TypeError, lambda: b1.xreplace([b1, b2]))
for f in (exp, Function('f')):
assert f.xreplace({}) == f
assert f.xreplace({}, hack2=True) == f
assert f.xreplace({f: b1}) == b1
assert f.xreplace({f: b1}, hack2=True) == b1
def test_preorder_traversal():
expr = Basic(b21, b3)
assert list(
preorder_traversal(expr)) == [expr, b21, b2, b1, b1, b3, b2, b1]
assert list(preorder_traversal(('abc', ('d', 'ef')))) == [
('abc', ('d', 'ef')), 'abc', ('d', 'ef'), 'd', 'ef']
result = []
pt = preorder_traversal(expr)
for i in pt:
result.append(i)
if i == b2:
pt.skip()
assert result == [expr, b21, b2, b1, b3, b2]
w, x, y, z = symbols('w:z')
expr = z + w*(x + y)
assert list(preorder_traversal([expr], keys=default_sort_key)) == \
[[w*(x + y) + z], w*(x + y) + z, z, w*(x + y), w, x + y, x, y]
assert list(preorder_traversal((x + y)*z, keys=True)) == \
[z*(x + y), z, x + y, x, y]
def test_sorted_args():
x = symbols('x')
assert b21._sorted_args == b21.args
raises(AttributeError, lambda: x._sorted_args)
def test_call():
x, y = symbols('x y')
# See the long history of this in issues 5026 and 5105.
raises(TypeError, lambda: sin(x)({ x : 1, sin(x) : 2}))
raises(TypeError, lambda: sin(x)(1))
# No effect as there are no callables
assert sin(x).rcall(1) == sin(x)
assert (1 + sin(x)).rcall(1) == 1 + sin(x)
# Effect in the pressence of callables
l = Lambda(x, 2*x)
assert (l + x).rcall(y) == 2*y + x
assert (x**l).rcall(2) == x**4
# TODO UndefinedFunction does not subclass Expr
#f = Function('f')
#assert (2*f)(x) == 2*f(x)
assert (Q.real & Q.positive).rcall(x) == Q.real(x) & Q.positive(x)
def test_rewrite():
x, y, z = symbols('x y z')
a, b = symbols('a b')
f1 = sin(x) + cos(x)
assert f1.rewrite(cos,exp) == exp(I*x)/2 + sin(x) + exp(-I*x)/2
assert f1.rewrite([cos],sin) == sin(x) + sin(x + pi/2, evaluate=False)
f2 = sin(x) + cos(y)/gamma(z)
assert f2.rewrite(sin,exp) == -I*(exp(I*x) - exp(-I*x))/2 + cos(y)/gamma(z)
assert f1.rewrite() == f1
def test_literal_evalf_is_number_is_zero_is_comparable():
from sympy.integrals.integrals import Integral
from sympy.core.symbol import symbols
from sympy.core.function import Function
from sympy.functions.elementary.trigonometric import cos, sin
x = symbols('x')
f = Function('f')
# issue 5033
assert f.is_number is False
# issue 6646
assert f(1).is_number is False
i = Integral(0, (x, x, x))
# expressions that are symbolically 0 can be difficult to prove
# so in case there is some easy way to know if something is 0
# it should appear in the is_zero property for that object;
# if is_zero is true evalf should always be able to compute that
# zero
assert i.n() == 0
assert i.is_zero
assert i.is_number is False
assert i.evalf(2, strict=False) == 0
# issue 10268
n = sin(1)**2 + cos(1)**2 - 1
assert n.is_comparable is False
assert n.n(2).is_comparable is False
assert n.n(2).n(2).is_comparable
def test_as_Basic():
assert as_Basic(1) is S.One
assert as_Basic(()) == Tuple()
raises(TypeError, lambda: as_Basic([]))
def test_atomic():
g, h = map(Function, 'gh')
x = symbols('x')
assert _atomic(g(x + h(x))) == {g(x + h(x))}
assert _atomic(g(x + h(x)), recursive=True) == {h(x), x, g(x + h(x))}
assert _atomic(1) == set()
assert _atomic(Basic(1,2)) == {Basic(1, 2)}
def test_as_dummy():
u, v, x, y, z, _0, _1 = symbols('u v x y z _0 _1')
assert Lambda(x, x + 1).as_dummy() == Lambda(_0, _0 + 1)
assert Lambda(x, x + _0).as_dummy() == Lambda(_1, _0 + _1)
assert (1 + Sum(x, (x, 1, x))).as_dummy() == 1 + Sum(_0, (_0, 1, x))
def test_canonical_variables():
x, i0, i1 = symbols('x _:2')
assert Integral(x, (x, x + 1)).canonical_variables == {x: i0}
assert Integral(x, (x, x + i0)).canonical_variables == {x: i1}
def test_replace_exceptions():
from sympy import Wild
x, y = symbols('x y')
e = (x**2 + x*y)
raises(TypeError, lambda: e.replace(sin, 2))
b = Wild('b')
c = Wild('c')
raises(TypeError, lambda: e.replace(b*c, c.is_real))
raises(TypeError, lambda: e.replace(b.is_real, 1))
raises(TypeError, lambda: e.replace(lambda d: d.is_Number, 1))
|
ec2aae73b998b09ef59550ded78abbef38a7f99a36a807311a1617b77a7c3c09
|
from sympy.utilities.pytest import XFAIL, raises
from sympy import (S, Symbol, symbols, nan, oo, I, pi, Float, And, Or,
Not, Implies, Xor, zoo, sqrt, Rational, simplify, Function, Eq,
log, cos, sin, Add)
from sympy.core.compatibility import range
from sympy.core.relational import (Relational, Equality, Unequality,
GreaterThan, LessThan, StrictGreaterThan,
StrictLessThan, Rel, Eq, Lt, Le,
Gt, Ge, Ne, _canonical)
from sympy.sets.sets import Interval, FiniteSet
x, y, z, t = symbols('x,y,z,t')
def test_rel_ne():
assert Relational(x, y, '!=') == Ne(x, y)
# issue 6116
p = Symbol('p', positive=True)
assert Ne(p, 0) is S.true
def test_rel_subs():
e = Relational(x, y, '==')
e = e.subs(x, z)
assert isinstance(e, Equality)
assert e.lhs == z
assert e.rhs == y
e = Relational(x, y, '>=')
e = e.subs(x, z)
assert isinstance(e, GreaterThan)
assert e.lhs == z
assert e.rhs == y
e = Relational(x, y, '<=')
e = e.subs(x, z)
assert isinstance(e, LessThan)
assert e.lhs == z
assert e.rhs == y
e = Relational(x, y, '>')
e = e.subs(x, z)
assert isinstance(e, StrictGreaterThan)
assert e.lhs == z
assert e.rhs == y
e = Relational(x, y, '<')
e = e.subs(x, z)
assert isinstance(e, StrictLessThan)
assert e.lhs == z
assert e.rhs == y
e = Eq(x, 0)
assert e.subs(x, 0) is S.true
assert e.subs(x, 1) is S.false
def test_wrappers():
e = x + x**2
res = Relational(y, e, '==')
assert Rel(y, x + x**2, '==') == res
assert Eq(y, x + x**2) == res
res = Relational(y, e, '<')
assert Lt(y, x + x**2) == res
res = Relational(y, e, '<=')
assert Le(y, x + x**2) == res
res = Relational(y, e, '>')
assert Gt(y, x + x**2) == res
res = Relational(y, e, '>=')
assert Ge(y, x + x**2) == res
res = Relational(y, e, '!=')
assert Ne(y, x + x**2) == res
def test_Eq():
assert Eq(x**2) == Eq(x**2, 0)
assert Eq(x**2) != Eq(x**2, 1)
assert Eq(x, x) # issue 5719
# issue 6116
p = Symbol('p', positive=True)
assert Eq(p, 0) is S.false
# issue 13348
assert Eq(True, 1) is S.false
def test_rel_Infinity():
# NOTE: All of these are actually handled by sympy.core.Number, and do
# not create Relational objects.
assert (oo > oo) is S.false
assert (oo > -oo) is S.true
assert (oo > 1) is S.true
assert (oo < oo) is S.false
assert (oo < -oo) is S.false
assert (oo < 1) is S.false
assert (oo >= oo) is S.true
assert (oo >= -oo) is S.true
assert (oo >= 1) is S.true
assert (oo <= oo) is S.true
assert (oo <= -oo) is S.false
assert (oo <= 1) is S.false
assert (-oo > oo) is S.false
assert (-oo > -oo) is S.false
assert (-oo > 1) is S.false
assert (-oo < oo) is S.true
assert (-oo < -oo) is S.false
assert (-oo < 1) is S.true
assert (-oo >= oo) is S.false
assert (-oo >= -oo) is S.true
assert (-oo >= 1) is S.false
assert (-oo <= oo) is S.true
assert (-oo <= -oo) is S.true
assert (-oo <= 1) is S.true
def test_bool():
assert Eq(0, 0) is S.true
assert Eq(1, 0) is S.false
assert Ne(0, 0) is S.false
assert Ne(1, 0) is S.true
assert Lt(0, 1) is S.true
assert Lt(1, 0) is S.false
assert Le(0, 1) is S.true
assert Le(1, 0) is S.false
assert Le(0, 0) is S.true
assert Gt(1, 0) is S.true
assert Gt(0, 1) is S.false
assert Ge(1, 0) is S.true
assert Ge(0, 1) is S.false
assert Ge(1, 1) is S.true
assert Eq(I, 2) is S.false
assert Ne(I, 2) is S.true
raises(TypeError, lambda: Gt(I, 2))
raises(TypeError, lambda: Ge(I, 2))
raises(TypeError, lambda: Lt(I, 2))
raises(TypeError, lambda: Le(I, 2))
a = Float('.000000000000000000001', '')
b = Float('.0000000000000000000001', '')
assert Eq(pi + a, pi + b) is S.false
def test_rich_cmp():
assert (x < y) == Lt(x, y)
assert (x <= y) == Le(x, y)
assert (x > y) == Gt(x, y)
assert (x >= y) == Ge(x, y)
def test_doit():
from sympy import Symbol
p = Symbol('p', positive=True)
n = Symbol('n', negative=True)
np = Symbol('np', nonpositive=True)
nn = Symbol('nn', nonnegative=True)
assert Gt(p, 0).doit() is S.true
assert Gt(p, 1).doit() == Gt(p, 1)
assert Ge(p, 0).doit() is S.true
assert Le(p, 0).doit() is S.false
assert Lt(n, 0).doit() is S.true
assert Le(np, 0).doit() is S.true
assert Gt(nn, 0).doit() == Gt(nn, 0)
assert Lt(nn, 0).doit() is S.false
assert Eq(x, 0).doit() == Eq(x, 0)
def test_new_relational():
x = Symbol('x')
assert Eq(x) == Relational(x, 0) # None ==> Equality
assert Eq(x) == Relational(x, 0, '==')
assert Eq(x) == Relational(x, 0, 'eq')
assert Eq(x) == Equality(x, 0)
assert Eq(x, -1) == Relational(x, -1) # None ==> Equality
assert Eq(x, -1) == Relational(x, -1, '==')
assert Eq(x, -1) == Relational(x, -1, 'eq')
assert Eq(x, -1) == Equality(x, -1)
assert Eq(x) != Relational(x, 1) # None ==> Equality
assert Eq(x) != Relational(x, 1, '==')
assert Eq(x) != Relational(x, 1, 'eq')
assert Eq(x) != Equality(x, 1)
assert Eq(x, -1) != Relational(x, 1) # None ==> Equality
assert Eq(x, -1) != Relational(x, 1, '==')
assert Eq(x, -1) != Relational(x, 1, 'eq')
assert Eq(x, -1) != Equality(x, 1)
assert Ne(x, 0) == Relational(x, 0, '!=')
assert Ne(x, 0) == Relational(x, 0, '<>')
assert Ne(x, 0) == Relational(x, 0, 'ne')
assert Ne(x, 0) == Unequality(x, 0)
assert Ne(x, 0) != Relational(x, 1, '!=')
assert Ne(x, 0) != Relational(x, 1, '<>')
assert Ne(x, 0) != Relational(x, 1, 'ne')
assert Ne(x, 0) != Unequality(x, 1)
assert Ge(x, 0) == Relational(x, 0, '>=')
assert Ge(x, 0) == Relational(x, 0, 'ge')
assert Ge(x, 0) == GreaterThan(x, 0)
assert Ge(x, 1) != Relational(x, 0, '>=')
assert Ge(x, 1) != Relational(x, 0, 'ge')
assert Ge(x, 1) != GreaterThan(x, 0)
assert (x >= 1) == Relational(x, 1, '>=')
assert (x >= 1) == Relational(x, 1, 'ge')
assert (x >= 1) == GreaterThan(x, 1)
assert (x >= 0) != Relational(x, 1, '>=')
assert (x >= 0) != Relational(x, 1, 'ge')
assert (x >= 0) != GreaterThan(x, 1)
assert Le(x, 0) == Relational(x, 0, '<=')
assert Le(x, 0) == Relational(x, 0, 'le')
assert Le(x, 0) == LessThan(x, 0)
assert Le(x, 1) != Relational(x, 0, '<=')
assert Le(x, 1) != Relational(x, 0, 'le')
assert Le(x, 1) != LessThan(x, 0)
assert (x <= 1) == Relational(x, 1, '<=')
assert (x <= 1) == Relational(x, 1, 'le')
assert (x <= 1) == LessThan(x, 1)
assert (x <= 0) != Relational(x, 1, '<=')
assert (x <= 0) != Relational(x, 1, 'le')
assert (x <= 0) != LessThan(x, 1)
assert Gt(x, 0) == Relational(x, 0, '>')
assert Gt(x, 0) == Relational(x, 0, 'gt')
assert Gt(x, 0) == StrictGreaterThan(x, 0)
assert Gt(x, 1) != Relational(x, 0, '>')
assert Gt(x, 1) != Relational(x, 0, 'gt')
assert Gt(x, 1) != StrictGreaterThan(x, 0)
assert (x > 1) == Relational(x, 1, '>')
assert (x > 1) == Relational(x, 1, 'gt')
assert (x > 1) == StrictGreaterThan(x, 1)
assert (x > 0) != Relational(x, 1, '>')
assert (x > 0) != Relational(x, 1, 'gt')
assert (x > 0) != StrictGreaterThan(x, 1)
assert Lt(x, 0) == Relational(x, 0, '<')
assert Lt(x, 0) == Relational(x, 0, 'lt')
assert Lt(x, 0) == StrictLessThan(x, 0)
assert Lt(x, 1) != Relational(x, 0, '<')
assert Lt(x, 1) != Relational(x, 0, 'lt')
assert Lt(x, 1) != StrictLessThan(x, 0)
assert (x < 1) == Relational(x, 1, '<')
assert (x < 1) == Relational(x, 1, 'lt')
assert (x < 1) == StrictLessThan(x, 1)
assert (x < 0) != Relational(x, 1, '<')
assert (x < 0) != Relational(x, 1, 'lt')
assert (x < 0) != StrictLessThan(x, 1)
# finally, some fuzz testing
from random import randint
from sympy.core.compatibility import unichr
for i in range(100):
while 1:
strtype, length = (unichr, 65535) if randint(0, 1) else (chr, 255)
relation_type = strtype(randint(0, length))
if randint(0, 1):
relation_type += strtype(randint(0, length))
if relation_type not in ('==', 'eq', '!=', '<>', 'ne', '>=', 'ge',
'<=', 'le', '>', 'gt', '<', 'lt', ':=',
'+=', '-=', '*=', '/=', '%='):
break
raises(ValueError, lambda: Relational(x, 1, relation_type))
assert all(Relational(x, 0, op).rel_op == '==' for op in ('eq', '=='))
assert all(Relational(x, 0, op).rel_op == '!=' for op in ('ne', '<>', '!='))
assert all(Relational(x, 0, op).rel_op == '>' for op in ('gt', '>'))
assert all(Relational(x, 0, op).rel_op == '<' for op in ('lt', '<'))
assert all(Relational(x, 0, op).rel_op == '>=' for op in ('ge', '>='))
assert all(Relational(x, 0, op).rel_op == '<=' for op in ('le', '<='))
def test_relational_bool_output():
# https://github.com/sympy/sympy/issues/5931
raises(TypeError, lambda: bool(x > 3))
raises(TypeError, lambda: bool(x >= 3))
raises(TypeError, lambda: bool(x < 3))
raises(TypeError, lambda: bool(x <= 3))
raises(TypeError, lambda: bool(Eq(x, 3)))
raises(TypeError, lambda: bool(Ne(x, 3)))
def test_relational_logic_symbols():
# See issue 6204
assert (x < y) & (z < t) == And(x < y, z < t)
assert (x < y) | (z < t) == Or(x < y, z < t)
assert ~(x < y) == Not(x < y)
assert (x < y) >> (z < t) == Implies(x < y, z < t)
assert (x < y) << (z < t) == Implies(z < t, x < y)
assert (x < y) ^ (z < t) == Xor(x < y, z < t)
assert isinstance((x < y) & (z < t), And)
assert isinstance((x < y) | (z < t), Or)
assert isinstance(~(x < y), GreaterThan)
assert isinstance((x < y) >> (z < t), Implies)
assert isinstance((x < y) << (z < t), Implies)
assert isinstance((x < y) ^ (z < t), (Or, Xor))
def test_univariate_relational_as_set():
assert (x > 0).as_set() == Interval(0, oo, True, True)
assert (x >= 0).as_set() == Interval(0, oo)
assert (x < 0).as_set() == Interval(-oo, 0, True, True)
assert (x <= 0).as_set() == Interval(-oo, 0)
assert Eq(x, 0).as_set() == FiniteSet(0)
assert Ne(x, 0).as_set() == Interval(-oo, 0, True, True) + \
Interval(0, oo, True, True)
assert (x**2 >= 4).as_set() == Interval(-oo, -2) + Interval(2, oo)
@XFAIL
def test_multivariate_relational_as_set():
assert (x*y >= 0).as_set() == Interval(0, oo)*Interval(0, oo) + \
Interval(-oo, 0)*Interval(-oo, 0)
def test_Not():
assert Not(Equality(x, y)) == Unequality(x, y)
assert Not(Unequality(x, y)) == Equality(x, y)
assert Not(StrictGreaterThan(x, y)) == LessThan(x, y)
assert Not(StrictLessThan(x, y)) == GreaterThan(x, y)
assert Not(GreaterThan(x, y)) == StrictLessThan(x, y)
assert Not(LessThan(x, y)) == StrictGreaterThan(x, y)
def test_evaluate():
assert str(Eq(x, x, evaluate=False)) == 'Eq(x, x)'
assert Eq(x, x, evaluate=False).doit() == S.true
assert str(Ne(x, x, evaluate=False)) == 'Ne(x, x)'
assert Ne(x, x, evaluate=False).doit() == S.false
assert str(Ge(x, x, evaluate=False)) == 'x >= x'
assert str(Le(x, x, evaluate=False)) == 'x <= x'
assert str(Gt(x, x, evaluate=False)) == 'x > x'
assert str(Lt(x, x, evaluate=False)) == 'x < x'
def assert_all_ineq_raise_TypeError(a, b):
raises(TypeError, lambda: a > b)
raises(TypeError, lambda: a >= b)
raises(TypeError, lambda: a < b)
raises(TypeError, lambda: a <= b)
raises(TypeError, lambda: b > a)
raises(TypeError, lambda: b >= a)
raises(TypeError, lambda: b < a)
raises(TypeError, lambda: b <= a)
def assert_all_ineq_give_class_Inequality(a, b):
"""All inequality operations on `a` and `b` result in class Inequality."""
from sympy.core.relational import _Inequality as Inequality
assert isinstance(a > b, Inequality)
assert isinstance(a >= b, Inequality)
assert isinstance(a < b, Inequality)
assert isinstance(a <= b, Inequality)
assert isinstance(b > a, Inequality)
assert isinstance(b >= a, Inequality)
assert isinstance(b < a, Inequality)
assert isinstance(b <= a, Inequality)
def test_imaginary_compare_raises_TypeError():
# See issue #5724
assert_all_ineq_raise_TypeError(I, x)
def test_complex_compare_not_real():
# two cases which are not real
y = Symbol('y', imaginary=True)
z = Symbol('z', complex=True, real=False)
for w in (y, z):
assert_all_ineq_raise_TypeError(2, w)
# some cases which should remain un-evaluated
t = Symbol('t')
x = Symbol('x', real=True)
z = Symbol('z', complex=True)
for w in (x, z, t):
assert_all_ineq_give_class_Inequality(2, w)
def test_imaginary_and_inf_compare_raises_TypeError():
# See pull request #7835
y = Symbol('y', imaginary=True)
assert_all_ineq_raise_TypeError(oo, y)
assert_all_ineq_raise_TypeError(-oo, y)
def test_complex_pure_imag_not_ordered():
raises(TypeError, lambda: 2*I < 3*I)
# more generally
x = Symbol('x', real=True, nonzero=True)
y = Symbol('y', imaginary=True)
z = Symbol('z', complex=True)
assert_all_ineq_raise_TypeError(I, y)
t = I*x # an imaginary number, should raise errors
assert_all_ineq_raise_TypeError(2, t)
t = -I*y # a real number, so no errors
assert_all_ineq_give_class_Inequality(2, t)
t = I*z # unknown, should be unevaluated
assert_all_ineq_give_class_Inequality(2, t)
def test_x_minus_y_not_same_as_x_lt_y():
"""
A consequence of pull request #7792 is that `x - y < 0` and `x < y`
are not synonymous.
"""
x = I + 2
y = I + 3
raises(TypeError, lambda: x < y)
assert x - y < 0
ineq = Lt(x, y, evaluate=False)
raises(TypeError, lambda: ineq.doit())
assert ineq.lhs - ineq.rhs < 0
t = Symbol('t', imaginary=True)
x = 2 + t
y = 3 + t
ineq = Lt(x, y, evaluate=False)
raises(TypeError, lambda: ineq.doit())
assert ineq.lhs - ineq.rhs < 0
# this one should give error either way
x = I + 2
y = 2*I + 3
raises(TypeError, lambda: x < y)
raises(TypeError, lambda: x - y < 0)
def test_nan_equality_exceptions():
# See issue #7774
import random
assert Equality(nan, nan) is S.false
assert Unequality(nan, nan) is S.true
# See issue #7773
A = (x, S(0), S(1)/3, pi, oo, -oo)
assert Equality(nan, random.choice(A)) is S.false
assert Equality(random.choice(A), nan) is S.false
assert Unequality(nan, random.choice(A)) is S.true
assert Unequality(random.choice(A), nan) is S.true
def test_nan_inequality_raise_errors():
# See discussion in pull request #7776. We test inequalities with
# a set including examples of various classes.
for q in (x, S(0), S(10), S(1)/3, pi, S(1.3), oo, -oo, nan):
assert_all_ineq_raise_TypeError(q, nan)
def test_nan_complex_inequalities():
# Comparisons of NaN with non-real raise errors, we're not too
# fussy whether its the NaN error or complex error.
for r in (I, zoo, Symbol('z', imaginary=True)):
assert_all_ineq_raise_TypeError(r, nan)
def test_complex_infinity_inequalities():
raises(TypeError, lambda: zoo > 0)
raises(TypeError, lambda: zoo >= 0)
raises(TypeError, lambda: zoo < 0)
raises(TypeError, lambda: zoo <= 0)
def test_inequalities_symbol_name_same():
"""Using the operator and functional forms should give same results."""
# We test all combinations from a set
# FIXME: could replace with random selection after test passes
A = (x, y, S(0), S(1)/3, pi, oo, -oo)
for a in A:
for b in A:
assert Gt(a, b) == (a > b)
assert Lt(a, b) == (a < b)
assert Ge(a, b) == (a >= b)
assert Le(a, b) == (a <= b)
for b in (y, S(0), S(1)/3, pi, oo, -oo):
assert Gt(x, b, evaluate=False) == (x > b)
assert Lt(x, b, evaluate=False) == (x < b)
assert Ge(x, b, evaluate=False) == (x >= b)
assert Le(x, b, evaluate=False) == (x <= b)
for b in (y, S(0), S(1)/3, pi, oo, -oo):
assert Gt(b, x, evaluate=False) == (b > x)
assert Lt(b, x, evaluate=False) == (b < x)
assert Ge(b, x, evaluate=False) == (b >= x)
assert Le(b, x, evaluate=False) == (b <= x)
def test_inequalities_symbol_name_same_complex():
"""Using the operator and functional forms should give same results.
With complex non-real numbers, both should raise errors.
"""
# FIXME: could replace with random selection after test passes
for a in (x, S(0), S(1)/3, pi, oo):
raises(TypeError, lambda: Gt(a, I))
raises(TypeError, lambda: a > I)
raises(TypeError, lambda: Lt(a, I))
raises(TypeError, lambda: a < I)
raises(TypeError, lambda: Ge(a, I))
raises(TypeError, lambda: a >= I)
raises(TypeError, lambda: Le(a, I))
raises(TypeError, lambda: a <= I)
def test_inequalities_cant_sympify_other():
# see issue 7833
from operator import gt, lt, ge, le
bar = "foo"
for a in (x, S(0), S(1)/3, pi, I, zoo, oo, -oo, nan):
for op in (lt, gt, le, ge):
raises(TypeError, lambda: op(a, bar))
def test_ineq_avoid_wild_symbol_flip():
# see issue #7951, we try to avoid this internally, e.g., by using
# __lt__ instead of "<".
from sympy.core.symbol import Wild
p = symbols('p', cls=Wild)
# x > p might flip, but Gt should not:
assert Gt(x, p) == Gt(x, p, evaluate=False)
# Previously failed as 'p > x':
e = Lt(x, y).subs({y: p})
assert e == Lt(x, p, evaluate=False)
# Previously failed as 'p <= x':
e = Ge(x, p).doit()
assert e == Ge(x, p, evaluate=False)
def test_issue_8245():
a = S("6506833320952669167898688709329/5070602400912917605986812821504")
q = a.n(10)
assert (a == q) is True
assert (a != q) is False
assert (a > q) == False
assert (a < q) == False
assert (a >= q) == True
assert (a <= q) == True
a = sqrt(2)
r = Rational(str(a.n(30)))
assert (r == a) is False
assert (r != a) is True
assert (r > a) == True
assert (r < a) == False
assert (r >= a) == True
assert (r <= a) == False
a = sqrt(2)
r = Rational(str(a.n(29)))
assert (r == a) is False
assert (r != a) is True
assert (r > a) == False
assert (r < a) == True
assert (r >= a) == False
assert (r <= a) == True
assert Eq(log(cos(2)**2 + sin(2)**2), 0) == True
def test_issue_8449():
p = Symbol('p', nonnegative=True)
assert Lt(-oo, p)
assert Ge(-oo, p) is S.false
assert Gt(oo, -p)
assert Le(oo, -p) is S.false
def test_simplify_relational():
assert simplify(x*(y + 1) - x*y - x + 1 < x) == (x > 1)
r = S(1) < x
# canonical operations are not the same as simplification,
# so if there is no simplification, canonicalization will
# be done unless the measure forbids it
assert simplify(r) == r.canonical
assert simplify(r, ratio=0) != r.canonical
# this is not a random test; in _eval_simplify
# this will simplify to S.false and that is the
# reason for the 'if r.is_Relational' in Relational's
# _eval_simplify routine
assert simplify(-(2**(3*pi/2) + 6**pi)**(1/pi) +
2*(2**(pi/2) + 3**pi)**(1/pi) < 0) is S.false
# canonical at least
for f in (Eq, Ne):
f(y, x).simplify() == f(x, y)
f(x - 1, 0).simplify() == f(x, 1)
f(x - 1, x).simplify() == S.false
f(2*x - 1, x).simplify() == f(x, 1)
f(2*x, 4).simplify() == f(x, 2)
z = cos(1)**2 + sin(1)**2 - 1 # z.is_zero is None
f(z*x, 0).simplify() == f(z*x, 0)
def test_equals():
w, x, y, z = symbols('w:z')
f = Function('f')
assert Eq(x, 1).equals(Eq(x*(y + 1) - x*y - x + 1, x))
assert Eq(x, y).equals(x < y, True) == False
assert Eq(x, f(1)).equals(Eq(x, f(2)), True) == f(1) - f(2)
assert Eq(f(1), y).equals(Eq(f(2), y), True) == f(1) - f(2)
assert Eq(x, f(1)).equals(Eq(f(2), x), True) == f(1) - f(2)
assert Eq(f(1), x).equals(Eq(x, f(2)), True) == f(1) - f(2)
assert Eq(w, x).equals(Eq(y, z), True) == False
assert Eq(f(1), f(2)).equals(Eq(f(3), f(4)), True) == f(1) - f(3)
assert (x < y).equals(y > x, True) == True
assert (x < y).equals(y >= x, True) == False
assert (x < y).equals(z < y, True) == False
assert (x < y).equals(x < z, True) == False
assert (x < f(1)).equals(x < f(2), True) == f(1) - f(2)
assert (f(1) < x).equals(f(2) < x, True) == f(1) - f(2)
def test_reversed():
assert (x < y).reversed == (y > x)
assert (x <= y).reversed == (y >= x)
assert Eq(x, y, evaluate=False).reversed == Eq(y, x, evaluate=False)
assert Ne(x, y, evaluate=False).reversed == Ne(y, x, evaluate=False)
assert (x >= y).reversed == (y <= x)
assert (x > y).reversed == (y < x)
def test_canonical():
c = [i.canonical for i in (
x + y < z,
x + 2 > 3,
x < 2,
S(2) > x,
x**2 > -x/y,
Gt(3, 2, evaluate=False)
)]
assert [i.canonical for i in c] == c
assert [i.reversed.canonical for i in c] == c
assert not any(i.lhs.is_Number and not i.rhs.is_Number for i in c)
c = [i.reversed.func(i.rhs, i.lhs, evaluate=False).canonical for i in c]
assert [i.canonical for i in c] == c
assert [i.reversed.canonical for i in c] == c
assert not any(i.lhs.is_Number and not i.rhs.is_Number for i in c)
@XFAIL
def test_issue_8444():
x = symbols('x', real=True)
assert (x <= oo) == (x >= -oo) == True
x = symbols('x')
assert x >= floor(x)
assert (x < floor(x)) == False
assert Gt(x, floor(x)) == Gt(x, floor(x), evaluate=False)
assert Ge(x, floor(x)) == Ge(x, floor(x), evaluate=False)
assert x <= ceiling(x)
assert (x > ceiling(x)) == False
assert Lt(x, ceiling(x)) == Lt(x, ceiling(x), evaluate=False)
assert Le(x, ceiling(x)) == Le(x, ceiling(x), evaluate=False)
i = symbols('i', integer=True)
assert (i > floor(i)) == False
assert (i < ceiling(i)) == False
def test_issue_10304():
d = cos(1)**2 + sin(1)**2 - 1
assert d.is_comparable is False # if this fails, find a new d
e = 1 + d*I
assert simplify(Eq(e, 0)) is S.false
def test_issue_10401():
x = symbols('x')
fin = symbols('inf', finite=True)
inf = symbols('inf', infinite=True)
inf2 = symbols('inf2', infinite=True)
zero = symbols('z', zero=True)
nonzero = symbols('nz', zero=False, finite=True)
assert Eq(1/(1/x + 1), 1).func is Eq
assert Eq(1/(1/x + 1), 1).subs(x, S.ComplexInfinity) is S.true
assert Eq(1/(1/fin + 1), 1) is S.false
T, F = S.true, S.false
assert Eq(fin, inf) is F
assert Eq(inf, inf2) is T and inf != inf2
assert Eq(inf/inf2, 0) is F
assert Eq(inf/fin, 0) is F
assert Eq(fin/inf, 0) is T
assert Eq(zero/nonzero, 0) is T and ((zero/nonzero) != 0)
assert Eq(inf, -inf) is F
assert Eq(fin/(fin + 1), 1) is S.false
o = symbols('o', odd=True)
assert Eq(o, 2*o) is S.false
p = symbols('p', positive=True)
assert Eq(p/(p - 1), 1) is F
def test_issue_10633():
assert Eq(True, False) == False
assert Eq(False, True) == False
assert Eq(True, True) == True
assert Eq(False, False) == True
def test_issue_10927():
x = symbols('x')
assert str(Eq(x, oo)) == 'Eq(x, oo)'
assert str(Eq(x, -oo)) == 'Eq(x, -oo)'
def test_issues_13081_12583_12534():
# 13081
r = Rational('905502432259640373/288230376151711744')
assert (r < pi) is S.false
assert (r > pi) is S.true
# 12583
v = sqrt(2)
u = sqrt(v) + 2/sqrt(10 - 8/sqrt(2 - v) + 4*v*(1/sqrt(2 - v) - 1))
assert (u >= 0) is S.true
# 12534; Rational vs NumberSymbol
# here are some precisions for which Rational forms
# at a lower and higher precision bracket the value of pi
# e.g. for p = 20:
# Rational(pi.n(p + 1)).n(25) = 3.14159265358979323846 2834
# pi.n(25) = 3.14159265358979323846 2643
# Rational(pi.n(p )).n(25) = 3.14159265358979323846 1987
assert [p for p in range(20, 50) if
(Rational(pi.n(p)) < pi) and
(pi < Rational(pi.n(p + 1)))
] == [20, 24, 27, 33, 37, 43, 48]
# pick one such precision and affirm that the reversed operation
# gives the opposite result, i.e. if x < y is true then x > y
# must be false
p = 20
# Rational vs NumberSymbol
G = [Rational(pi.n(i)) > pi for i in (p, p + 1)]
L = [Rational(pi.n(i)) < pi for i in (p, p + 1)]
assert G == [False, True]
assert all(i is not j for i, j in zip(L, G))
# Float vs NumberSymbol
G = [pi.n(i) > pi for i in (p, p + 1)]
L = [pi.n(i) < pi for i in (p, p + 1)]
assert G == [False, True]
assert all(i is not j for i, j in zip(L, G))
# Float vs Float
G = [pi.n(p) > pi.n(p + 1)]
L = [pi.n(p) < pi.n(p + 1)]
assert G == [True]
assert all(i is not j for i, j in zip(L, G))
# Float vs Rational
# the rational form is less than the floating representation
# at the same precision
assert [i for i in range(15, 50) if Rational(pi.n(i)) > pi.n(i)
] == []
# this should be the same if we reverse the relational
assert [i for i in range(15, 50) if pi.n(i) < Rational(pi.n(i))
] == []
def test_binary_symbols():
ans = set([x])
for f in Eq, Ne:
for t in S.true, S.false:
eq = f(x, S.true)
assert eq.binary_symbols == ans
assert eq.reversed.binary_symbols == ans
assert f(x, 1).binary_symbols == set()
def test_rel_args():
# can't have Boolean args; this is automatic with Python 3
# so this test and the __lt__, etc..., definitions in
# relational.py and boolalg.py which are marked with ///
# can be removed.
for op in ['<', '<=', '>', '>=']:
for b in (S.true, x < 1, And(x, y)):
for v in (0.1, 1, 2**32, t, S(1)):
raises(TypeError, lambda: Relational(b, v, op))
def test_Equality_rewrite_as_Add():
eq = Eq(x + y, y - x)
assert eq.rewrite(Add) == 2*x
assert eq.rewrite(Add, evaluate=None).args == (x, x, y, -y)
assert eq.rewrite(Add, evaluate=False).args == (x, y, x, -y)
def test_issue_15847():
a = Ne(x*(x+y), x**2 + x*y)
assert simplify(a) == False
|
06e31b84924633982ed54dbd2adbf5efc2f0e909efd622a8c96a75c82bb751b0
|
"""Tests that the IPython printing module is properly loaded. """
from sympy.interactive.session import init_ipython_session
from sympy.external import import_module
from sympy.utilities.pytest import raises
# run_cell was added in IPython 0.11
ipython = import_module("IPython", min_module_version="0.11")
# disable tests if ipython is not present
if not ipython:
disabled = True
def test_ipythonprinting():
# Initialize and setup IPython session
app = init_ipython_session()
app.run_cell("ip = get_ipython()")
app.run_cell("inst = ip.instance()")
app.run_cell("format = inst.display_formatter.format")
app.run_cell("from sympy import Symbol")
# Printing without printing extension
app.run_cell("a = format(Symbol('pi'))")
app.run_cell("a2 = format(Symbol('pi')**2)")
# Deal with API change starting at IPython 1.0
if int(ipython.__version__.split(".")[0]) < 1:
assert app.user_ns['a']['text/plain'] == "pi"
assert app.user_ns['a2']['text/plain'] == "pi**2"
else:
assert app.user_ns['a'][0]['text/plain'] == "pi"
assert app.user_ns['a2'][0]['text/plain'] == "pi**2"
# Load printing extension
app.run_cell("from sympy import init_printing")
app.run_cell("init_printing()")
# Printing with printing extension
app.run_cell("a = format(Symbol('pi'))")
app.run_cell("a2 = format(Symbol('pi')**2)")
# Deal with API change starting at IPython 1.0
if int(ipython.__version__.split(".")[0]) < 1:
assert app.user_ns['a']['text/plain'] in (u'\N{GREEK SMALL LETTER PI}', 'pi')
assert app.user_ns['a2']['text/plain'] in (u' 2\n\N{GREEK SMALL LETTER PI} ', ' 2\npi ')
else:
assert app.user_ns['a'][0]['text/plain'] in (u'\N{GREEK SMALL LETTER PI}', 'pi')
assert app.user_ns['a2'][0]['text/plain'] in (u' 2\n\N{GREEK SMALL LETTER PI} ', ' 2\npi ')
def test_print_builtin_option():
# Initialize and setup IPython session
app = init_ipython_session()
app.run_cell("ip = get_ipython()")
app.run_cell("inst = ip.instance()")
app.run_cell("format = inst.display_formatter.format")
app.run_cell("from sympy import Symbol")
app.run_cell("from sympy import init_printing")
app.run_cell("a = format({Symbol('pi'): 3.14, Symbol('n_i'): 3})")
# Deal with API change starting at IPython 1.0
if int(ipython.__version__.split(".")[0]) < 1:
text = app.user_ns['a']['text/plain']
raises(KeyError, lambda: app.user_ns['a']['text/latex'])
else:
text = app.user_ns['a'][0]['text/plain']
raises(KeyError, lambda: app.user_ns['a'][0]['text/latex'])
# Note : Unicode of Python2 is equivalent to str in Python3. In Python 3 we have one
# text type: str which holds Unicode data and two byte types bytes and bytearray.
# XXX: How can we make this ignore the terminal width? This test fails if
# the terminal is too narrow.
assert text in ("{pi: 3.14, n_i: 3}",
u'{n\N{LATIN SUBSCRIPT SMALL LETTER I}: 3, \N{GREEK SMALL LETTER PI}: 3.14}',
"{n_i: 3, pi: 3.14}",
u'{\N{GREEK SMALL LETTER PI}: 3.14, n\N{LATIN SUBSCRIPT SMALL LETTER I}: 3}')
# If we enable the default printing, then the dictionary's should render
# as a LaTeX version of the whole dict: ${\pi: 3.14, n_i: 3}$
app.run_cell("inst.display_formatter.formatters['text/latex'].enabled = True")
app.run_cell("init_printing(use_latex=True)")
app.run_cell("a = format({Symbol('pi'): 3.14, Symbol('n_i'): 3})")
# Deal with API change starting at IPython 1.0
if int(ipython.__version__.split(".")[0]) < 1:
text = app.user_ns['a']['text/plain']
latex = app.user_ns['a']['text/latex']
else:
text = app.user_ns['a'][0]['text/plain']
latex = app.user_ns['a'][0]['text/latex']
assert text in ("{pi: 3.14, n_i: 3}",
u'{n\N{LATIN SUBSCRIPT SMALL LETTER I}: 3, \N{GREEK SMALL LETTER PI}: 3.14}',
"{n_i: 3, pi: 3.14}",
u'{\N{GREEK SMALL LETTER PI}: 3.14, n\N{LATIN SUBSCRIPT SMALL LETTER I}: 3}')
assert latex == r'$\displaystyle \left\{ n_{i} : 3, \quad \pi : 3.14\right\}$'
app.run_cell("inst.display_formatter.formatters['text/latex'].enabled = True")
app.run_cell("init_printing(use_latex=True, print_builtin=False)")
app.run_cell("a = format({Symbol('pi'): 3.14, Symbol('n_i'): 3})")
# Deal with API change starting at IPython 1.0
if int(ipython.__version__.split(".")[0]) < 1:
text = app.user_ns['a']['text/plain']
raises(KeyError, lambda: app.user_ns['a']['text/latex'])
else:
text = app.user_ns['a'][0]['text/plain']
raises(KeyError, lambda: app.user_ns['a'][0]['text/latex'])
# Note : Unicode of Python2 is equivalent to str in Python3. In Python 3 we have one
# text type: str which holds Unicode data and two byte types bytes and bytearray.
# Python 3.3.3 + IPython 0.13.2 gives: '{n_i: 3, pi: 3.14}'
# Python 3.3.3 + IPython 1.1.0 gives: '{n_i: 3, pi: 3.14}'
# Python 2.7.5 + IPython 1.1.0 gives: '{pi: 3.14, n_i: 3}'
assert text in ("{pi: 3.14, n_i: 3}", "{n_i: 3, pi: 3.14}")
def test_builtin_containers():
# Initialize and setup IPython session
app = init_ipython_session()
app.run_cell("ip = get_ipython()")
app.run_cell("inst = ip.instance()")
app.run_cell("format = inst.display_formatter.format")
app.run_cell("inst.display_formatter.formatters['text/latex'].enabled = True")
app.run_cell("from sympy import init_printing, Matrix")
app.run_cell('init_printing(use_latex=True, use_unicode=False)')
# Make sure containers that shouldn't pretty print don't.
app.run_cell('a = format((True, False))')
app.run_cell('import sys')
app.run_cell('b = format(sys.flags)')
app.run_cell('c = format((Matrix([1, 2]),))')
# Deal with API change starting at IPython 1.0
if int(ipython.__version__.split(".")[0]) < 1:
assert app.user_ns['a']['text/plain'] == '(True, False)'
assert 'text/latex' not in app.user_ns['a']
assert app.user_ns['b']['text/plain'][:10] == 'sys.flags('
assert 'text/latex' not in app.user_ns['b']
assert app.user_ns['c']['text/plain'] == \
"""\
[1] \n\
([ ],)
[2] \
"""
assert app.user_ns['c']['text/latex'] == '$\\displaystyle \\left( \\left[\\begin{matrix}1\\\\2\\end{matrix}\\right]\\right)$'
else:
assert app.user_ns['a'][0]['text/plain'] == '(True, False)'
assert 'text/latex' not in app.user_ns['a'][0]
assert app.user_ns['b'][0]['text/plain'][:10] == 'sys.flags('
assert 'text/latex' not in app.user_ns['b'][0]
assert app.user_ns['c'][0]['text/plain'] == \
"""\
[1] \n\
([ ],)
[2] \
"""
assert app.user_ns['c'][0]['text/latex'] == '$\\displaystyle \\left( \\left[\\begin{matrix}1\\\\2\\end{matrix}\\right]\\right)$'
def test_matplotlib_bad_latex():
# Initialize and setup IPython session
app = init_ipython_session()
app.run_cell("import IPython")
app.run_cell("ip = get_ipython()")
app.run_cell("inst = ip.instance()")
app.run_cell("format = inst.display_formatter.format")
app.run_cell("from sympy import init_printing, Matrix")
app.run_cell("init_printing(use_latex='matplotlib')")
# The png formatter is not enabled by default in this context
app.run_cell("inst.display_formatter.formatters['image/png'].enabled = True")
# Make sure no warnings are raised by IPython
app.run_cell("import warnings")
# IPython.core.formatters.FormatterWarning was introduced in IPython 2.0
if int(ipython.__version__.split(".")[0]) < 2:
app.run_cell("warnings.simplefilter('error')")
else:
app.run_cell("warnings.simplefilter('error', IPython.core.formatters.FormatterWarning)")
# This should not raise an exception
app.run_cell("a = format(Matrix([1, 2, 3]))")
# issue 9799
app.run_cell("from sympy import Piecewise, Symbol, Eq")
app.run_cell("x = Symbol('x'); pw = format(Piecewise((1, Eq(x, 0)), (0, True)))")
|
e06ab494035f87b04d1c78a81a142ba53c2ca63466c6fb218b38e02877cb6fdf
|
"""Implementation of :class:`RationalField` class. """
from __future__ import print_function, division
from sympy.polys.domains.characteristiczero import CharacteristicZero
from sympy.polys.domains.field import Field
from sympy.polys.domains.simpledomain import SimpleDomain
from sympy.utilities import public
@public
class RationalField(Field, CharacteristicZero, SimpleDomain):
"""General class for rational fields. """
rep = 'QQ'
is_RationalField = is_QQ = True
is_Numerical = True
has_assoc_Ring = True
has_assoc_Field = True
def algebraic_field(self, *extension):
r"""Returns an algebraic field, i.e. `\mathbb{Q}(\alpha, \ldots)`. """
from sympy.polys.domains import AlgebraicField
return AlgebraicField(self, *extension)
def from_AlgebraicField(K1, a, K0):
"""Convert a ``ANP`` object to ``dtype``. """
if a.is_ground:
return K1.convert(a.LC(), K0.dom)
|
e150190bc16ed8e36010c1e8006c155d59d9b1e0f8c94eb947f285d4b494832f
|
"""Implementation of :class:`AlgebraicField` class. """
from __future__ import print_function, division
from sympy.polys.domains.characteristiczero import CharacteristicZero
from sympy.polys.domains.field import Field
from sympy.polys.domains.simpledomain import SimpleDomain
from sympy.polys.polyclasses import ANP
from sympy.polys.polyerrors import CoercionFailed, DomainError, NotAlgebraic, IsomorphismFailed
from sympy.utilities import public
@public
class AlgebraicField(Field, CharacteristicZero, SimpleDomain):
"""A class for representing algebraic number fields. """
dtype = ANP
is_AlgebraicField = is_Algebraic = True
is_Numerical = True
has_assoc_Ring = False
has_assoc_Field = True
def __init__(self, dom, *ext):
if not dom.is_QQ:
raise DomainError("ground domain must be a rational field")
from sympy.polys.numberfields import to_number_field
self.orig_ext = ext
self.ext = to_number_field(ext)
self.mod = self.ext.minpoly.rep
self.domain = self.dom = dom
self.ngens = 1
self.symbols = self.gens = (self.ext,)
self.unit = self([dom(1), dom(0)])
self.zero = self.dtype.zero(self.mod.rep, dom)
self.one = self.dtype.one(self.mod.rep, dom)
def new(self, element):
return self.dtype(element, self.mod.rep, self.dom)
def __str__(self):
return str(self.dom) + '<' + str(self.ext) + '>'
def __hash__(self):
return hash((self.__class__.__name__, self.dtype, self.dom, self.ext))
def __eq__(self, other):
"""Returns ``True`` if two domains are equivalent. """
return isinstance(other, AlgebraicField) and \
self.dtype == other.dtype and self.ext == other.ext
def algebraic_field(self, *extension):
r"""Returns an algebraic field, i.e. `\mathbb{Q}(\alpha, \ldots)`. """
return AlgebraicField(self.dom, *((self.ext,) + extension))
def to_sympy(self, a):
"""Convert ``a`` to a SymPy object. """
from sympy.polys.numberfields import AlgebraicNumber
return AlgebraicNumber(self.ext, a).as_expr()
def from_sympy(self, a):
"""Convert SymPy's expression to ``dtype``. """
try:
return self([self.dom.from_sympy(a)])
except CoercionFailed:
pass
from sympy.polys.numberfields import to_number_field
try:
return self(to_number_field(a, self.ext).native_coeffs())
except (NotAlgebraic, IsomorphismFailed):
raise CoercionFailed(
"%s is not a valid algebraic number in %s" % (a, self))
def from_ZZ_python(K1, a, K0):
"""Convert a Python ``int`` object to ``dtype``. """
return K1(K1.dom.convert(a, K0))
def from_QQ_python(K1, a, K0):
"""Convert a Python ``Fraction`` object to ``dtype``. """
return K1(K1.dom.convert(a, K0))
def from_ZZ_gmpy(K1, a, K0):
"""Convert a GMPY ``mpz`` object to ``dtype``. """
return K1(K1.dom.convert(a, K0))
def from_QQ_gmpy(K1, a, K0):
"""Convert a GMPY ``mpq`` object to ``dtype``. """
return K1(K1.dom.convert(a, K0))
def from_RealField(K1, a, K0):
"""Convert a mpmath ``mpf`` object to ``dtype``. """
return K1(K1.dom.convert(a, K0))
def get_ring(self):
"""Returns a ring associated with ``self``. """
raise DomainError('there is no ring associated with %s' % self)
def is_positive(self, a):
"""Returns True if ``a`` is positive. """
return self.dom.is_positive(a.LC())
def is_negative(self, a):
"""Returns True if ``a`` is negative. """
return self.dom.is_negative(a.LC())
def is_nonpositive(self, a):
"""Returns True if ``a`` is non-positive. """
return self.dom.is_nonpositive(a.LC())
def is_nonnegative(self, a):
"""Returns True if ``a`` is non-negative. """
return self.dom.is_nonnegative(a.LC())
def numer(self, a):
"""Returns numerator of ``a``. """
return a
def denom(self, a):
"""Returns denominator of ``a``. """
return self.one
|
7fbafdc9543c54823924962d99b40b8960f5cdacf8f1c7ee43bb32ca39da0b1f
|
"""Rational number type based on Python integers. """
from __future__ import print_function, division
import operator
from sympy.core.compatibility import integer_types
from sympy.core.numbers import Rational, Integer
from sympy.core.sympify import converter
from sympy.polys.polyutils import PicklableWithSlots
from sympy.polys.domains.domainelement import DomainElement
from sympy.printing.defaults import DefaultPrinting
from sympy.utilities import public
@public
class PythonRational(DefaultPrinting, PicklableWithSlots, DomainElement):
"""
Rational number type based on Python integers.
This was supposed to be needed for compatibility with older Python
versions which don't support Fraction. However, Fraction is very
slow so we don't use it anyway.
Examples
========
>>> from sympy.polys.domains import PythonRational
>>> PythonRational(1)
1
>>> PythonRational(2, 3)
2/3
>>> PythonRational(14, 10)
7/5
"""
__slots__ = ['p', 'q']
def parent(self):
from sympy.polys.domains import PythonRationalField
return PythonRationalField()
def __init__(self, p, q=1, _gcd=True):
from sympy.polys.domains.groundtypes import python_gcd as gcd
if isinstance(p, Integer):
p = p.p
elif isinstance(p, Rational):
p, q = p.p, p.q
if not q:
raise ZeroDivisionError('rational number')
elif q < 0:
p, q = -p, -q
if not p:
self.p = 0
self.q = 1
elif p == 1 or q == 1:
self.p = p
self.q = q
else:
if _gcd:
x = gcd(p, q)
if x != 1:
p //= x
q //= x
self.p = p
self.q = q
@classmethod
def new(cls, p, q):
obj = object.__new__(cls)
obj.p = p
obj.q = q
return obj
def __hash__(self):
if self.q == 1:
return hash(self.p)
else:
return hash((self.p, self.q))
def __int__(self):
p, q = self.p, self.q
if p < 0:
return -(-p//q)
return p//q
def __float__(self):
return float(self.p)/self.q
def __abs__(self):
return self.new(abs(self.p), self.q)
def __pos__(self):
return self.new(+self.p, self.q)
def __neg__(self):
return self.new(-self.p, self.q)
def __add__(self, other):
from sympy.polys.domains.groundtypes import python_gcd as gcd
if isinstance(other, PythonRational):
ap, aq, bp, bq = self.p, self.q, other.p, other.q
g = gcd(aq, bq)
if g == 1:
p = ap*bq + aq*bp
q = bq*aq
else:
q1, q2 = aq//g, bq//g
p, q = ap*q2 + bp*q1, q1*q2
g2 = gcd(p, g)
p, q = (p // g2), q * (g // g2)
elif isinstance(other, integer_types):
p = self.p + self.q*other
q = self.q
else:
return NotImplemented
return self.__class__(p, q, _gcd=False)
def __radd__(self, other):
if not isinstance(other, integer_types):
return NotImplemented
p = self.p + self.q*other
q = self.q
return self.__class__(p, q, _gcd=False)
def __sub__(self, other):
from sympy.polys.domains.groundtypes import python_gcd as gcd
if isinstance(other, PythonRational):
ap, aq, bp, bq = self.p, self.q, other.p, other.q
g = gcd(aq, bq)
if g == 1:
p = ap*bq - aq*bp
q = bq*aq
else:
q1, q2 = aq//g, bq//g
p, q = ap*q2 - bp*q1, q1*q2
g2 = gcd(p, g)
p, q = (p // g2), q * (g // g2)
elif isinstance(other, integer_types):
p = self.p - self.q*other
q = self.q
else:
return NotImplemented
return self.__class__(p, q, _gcd=False)
def __rsub__(self, other):
if not isinstance(other, integer_types):
return NotImplemented
p = self.q*other - self.p
q = self.q
return self.__class__(p, q, _gcd=False)
def __mul__(self, other):
from sympy.polys.domains.groundtypes import python_gcd as gcd
if isinstance(other, PythonRational):
ap, aq, bp, bq = self.p, self.q, other.p, other.q
x1 = gcd(ap, bq)
x2 = gcd(bp, aq)
p, q = ((ap//x1)*(bp//x2), (aq//x2)*(bq//x1))
elif isinstance(other, integer_types):
x = gcd(other, self.q)
p = self.p*(other//x)
q = self.q//x
else:
return NotImplemented
return self.__class__(p, q, _gcd=False)
def __rmul__(self, other):
from sympy.polys.domains.groundtypes import python_gcd as gcd
if not isinstance(other, integer_types):
return NotImplemented
x = gcd(self.q, other)
p = self.p*(other//x)
q = self.q//x
return self.__class__(p, q, _gcd=False)
def __div__(self, other):
from sympy.polys.domains.groundtypes import python_gcd as gcd
if isinstance(other, PythonRational):
ap, aq, bp, bq = self.p, self.q, other.p, other.q
x1 = gcd(ap, bp)
x2 = gcd(bq, aq)
p, q = ((ap//x1)*(bq//x2), (aq//x2)*(bp//x1))
elif isinstance(other, integer_types):
x = gcd(other, self.p)
p = self.p//x
q = self.q*(other//x)
else:
return NotImplemented
return self.__class__(p, q, _gcd=False)
__truediv__ = __div__
def __rdiv__(self, other):
from sympy.polys.domains.groundtypes import python_gcd as gcd
if not isinstance(other, integer_types):
return NotImplemented
x = gcd(self.p, other)
p = self.q*(other//x)
q = self.p//x
return self.__class__(p, q)
__rtruediv__ = __rdiv__
def __mod__(self, other):
return self.__class__(0)
def __divmod__(self, other):
return (self//other, self % other)
def __pow__(self, exp):
p, q = self.p, self.q
if exp < 0:
p, q, exp = q, p, -exp
return self.__class__(p**exp, q**exp, _gcd=False)
def __nonzero__(self):
return self.p != 0
__bool__ = __nonzero__
def __eq__(self, other):
if isinstance(other, PythonRational):
return self.q == other.q and self.p == other.p
elif isinstance(other, integer_types):
return self.q == 1 and self.p == other
else:
return False
def __ne__(self, other):
return not self == other
def _cmp(self, other, op):
try:
diff = self - other
except TypeError:
return NotImplemented
else:
return op(diff.p, 0)
def __lt__(self, other):
return self._cmp(other, operator.lt)
def __le__(self, other):
return self._cmp(other, operator.le)
def __gt__(self, other):
return self._cmp(other, operator.gt)
def __ge__(self, other):
return self._cmp(other, operator.ge)
@property
def numer(self):
return self.p
@property
def denom(self):
return self.q
numerator = numer
denominator = denom
def sympify_pythonrational(arg):
return Rational(arg.p, arg.q)
converter[PythonRational] = sympify_pythonrational
|
c2059a9ada2e68d3c2bf3e440e4cea9ef3c93db6554b3e7f54e8c2d172268a20
|
"""Implementation of :class:`FiniteField` class. """
from __future__ import print_function, division
from sympy.polys.domains.field import Field
from sympy.polys.domains.groundtypes import SymPyInteger
from sympy.polys.domains.modularinteger import ModularIntegerFactory
from sympy.polys.domains.simpledomain import SimpleDomain
from sympy.polys.polyerrors import CoercionFailed
from sympy.utilities import public
@public
class FiniteField(Field, SimpleDomain):
"""General class for finite fields. """
rep = 'FF'
is_FiniteField = is_FF = True
is_Numerical = True
has_assoc_Ring = False
has_assoc_Field = True
dom = None
mod = None
def __init__(self, mod, dom=None, symmetric=True):
if mod <= 0:
raise ValueError('modulus must be a positive integer, got %s' % mod)
if dom is None:
from sympy.polys.domains import ZZ
dom = ZZ
self.dtype = ModularIntegerFactory(mod, dom, symmetric, self)
self.zero = self.dtype(0)
self.one = self.dtype(1)
self.dom = dom
self.mod = mod
def __str__(self):
return 'GF(%s)' % self.mod
def __hash__(self):
return hash((self.__class__.__name__, self.dtype, self.mod, self.dom))
def __eq__(self, other):
"""Returns ``True`` if two domains are equivalent. """
return isinstance(other, FiniteField) and \
self.mod == other.mod and self.dom == other.dom
def characteristic(self):
"""Return the characteristic of this domain. """
return self.mod
def get_field(self):
"""Returns a field associated with ``self``. """
return self
def to_sympy(self, a):
"""Convert ``a`` to a SymPy object. """
return SymPyInteger(int(a))
def from_sympy(self, a):
"""Convert SymPy's Integer to SymPy's ``Integer``. """
if a.is_Integer:
return self.dtype(self.dom.dtype(int(a)))
elif a.is_Float and int(a) == a:
return self.dtype(self.dom.dtype(int(a)))
else:
raise CoercionFailed("expected an integer, got %s" % a)
def from_FF_python(K1, a, K0=None):
"""Convert ``ModularInteger(int)`` to ``dtype``. """
return K1.dtype(K1.dom.from_ZZ_python(a.val, K0.dom))
def from_ZZ_python(K1, a, K0=None):
"""Convert Python's ``int`` to ``dtype``. """
return K1.dtype(K1.dom.from_ZZ_python(a, K0))
def from_QQ_python(K1, a, K0=None):
"""Convert Python's ``Fraction`` to ``dtype``. """
if a.denominator == 1:
return K1.from_ZZ_python(a.numerator)
def from_FF_gmpy(K1, a, K0=None):
"""Convert ``ModularInteger(mpz)`` to ``dtype``. """
return K1.dtype(K1.dom.from_ZZ_gmpy(a.val, K0.dom))
def from_ZZ_gmpy(K1, a, K0=None):
"""Convert GMPY's ``mpz`` to ``dtype``. """
return K1.dtype(K1.dom.from_ZZ_gmpy(a, K0))
def from_QQ_gmpy(K1, a, K0=None):
"""Convert GMPY's ``mpq`` to ``dtype``. """
if a.denominator == 1:
return K1.from_ZZ_gmpy(a.numerator)
def from_RealField(K1, a, K0):
"""Convert mpmath's ``mpf`` to ``dtype``. """
p, q = K0.to_rational(a)
if q == 1:
return K1.dtype(self.dom.dtype(p))
|
1628cae2c3377c954f2e3e9802ccaf18ba014e2bde1067dfdd88f27228b9c976
|
"""Implementaton of :class:`PythonIntegerRing` class. """
from __future__ import print_function, division
from sympy.polys.domains.groundtypes import (
PythonInteger, SymPyInteger, python_sqrt,
python_factorial, python_gcdex, python_gcd, python_lcm,
)
from sympy.polys.domains.integerring import IntegerRing
from sympy.polys.polyerrors import CoercionFailed
from sympy.utilities import public
@public
class PythonIntegerRing(IntegerRing):
"""Integer ring based on Python's ``int`` type. """
dtype = PythonInteger
zero = dtype(0)
one = dtype(1)
alias = 'ZZ_python'
def __init__(self):
"""Allow instantiation of this domain. """
def to_sympy(self, a):
"""Convert ``a`` to a SymPy object. """
return SymPyInteger(a)
def from_sympy(self, a):
"""Convert SymPy's Integer to ``dtype``. """
if a.is_Integer:
return PythonInteger(a.p)
elif a.is_Float and int(a) == a:
return PythonInteger(int(a))
else:
raise CoercionFailed("expected an integer, got %s" % a)
def from_FF_python(K1, a, K0):
"""Convert ``ModularInteger(int)`` to Python's ``int``. """
return a.to_int()
def from_ZZ_python(K1, a, K0):
"""Convert Python's ``int`` to Python's ``int``. """
return a
def from_QQ_python(K1, a, K0):
"""Convert Python's ``Fraction`` to Python's ``int``. """
if a.denominator == 1:
return a.numerator
def from_FF_gmpy(K1, a, K0):
"""Convert ``ModularInteger(mpz)`` to Python's ``int``. """
return PythonInteger(a.to_int())
def from_ZZ_gmpy(K1, a, K0):
"""Convert GMPY's ``mpz`` to Python's ``int``. """
return PythonInteger(a)
def from_QQ_gmpy(K1, a, K0):
"""Convert GMPY's ``mpq`` to Python's ``int``. """
if a.denom() == 1:
return PythonInteger(a.numer())
def from_RealField(K1, a, K0):
"""Convert mpmath's ``mpf`` to Python's ``int``. """
p, q = K0.to_rational(a)
if q == 1:
return PythonInteger(p)
def gcdex(self, a, b):
"""Compute extended GCD of ``a`` and ``b``. """
return python_gcdex(a, b)
def gcd(self, a, b):
"""Compute GCD of ``a`` and ``b``. """
return python_gcd(a, b)
def lcm(self, a, b):
"""Compute LCM of ``a`` and ``b``. """
return python_lcm(a, b)
def sqrt(self, a):
"""Compute square root of ``a``. """
return python_sqrt(a)
def factorial(self, a):
"""Compute factorial of ``a``. """
return python_factorial(a)
|
3c817f627fef9b03b04bb38262e5efb7c2fbf733a2531f706d4def3b471bb0fd
|
"""Implementaton of :class:`GMPYRationalField` class. """
from __future__ import print_function, division
from sympy.polys.domains.groundtypes import (
GMPYRational, SymPyRational,
gmpy_numer, gmpy_denom, gmpy_factorial,
)
from sympy.polys.domains.rationalfield import RationalField
from sympy.polys.polyerrors import CoercionFailed
from sympy.utilities import public
@public
class GMPYRationalField(RationalField):
"""Rational field based on GMPY mpq class. """
dtype = GMPYRational
zero = dtype(0)
one = dtype(1)
tp = type(one)
alias = 'QQ_gmpy'
def __init__(self):
pass
def get_ring(self):
"""Returns ring associated with ``self``. """
from sympy.polys.domains import GMPYIntegerRing
return GMPYIntegerRing()
def to_sympy(self, a):
"""Convert `a` to a SymPy object. """
return SymPyRational(int(gmpy_numer(a)),
int(gmpy_denom(a)))
def from_sympy(self, a):
"""Convert SymPy's Integer to `dtype`. """
if a.is_Rational:
return GMPYRational(a.p, a.q)
elif a.is_Float:
from sympy.polys.domains import RR
return GMPYRational(*map(int, RR.to_rational(a)))
else:
raise CoercionFailed("expected `Rational` object, got %s" % a)
def from_ZZ_python(K1, a, K0):
"""Convert a Python `int` object to `dtype`. """
return GMPYRational(a)
def from_QQ_python(K1, a, K0):
"""Convert a Python `Fraction` object to `dtype`. """
return GMPYRational(a.numerator, a.denominator)
def from_ZZ_gmpy(K1, a, K0):
"""Convert a GMPY `mpz` object to `dtype`. """
return GMPYRational(a)
def from_QQ_gmpy(K1, a, K0):
"""Convert a GMPY `mpq` object to `dtype`. """
return a
def from_RealField(K1, a, K0):
"""Convert a mpmath `mpf` object to `dtype`. """
return GMPYRational(*map(int, K0.to_rational(a)))
def exquo(self, a, b):
"""Exact quotient of `a` and `b`, implies `__div__`. """
return GMPYRational(a) / GMPYRational(b)
def quo(self, a, b):
"""Quotient of `a` and `b`, implies `__div__`. """
return GMPYRational(a) / GMPYRational(b)
def rem(self, a, b):
"""Remainder of `a` and `b`, implies nothing. """
return self.zero
def div(self, a, b):
"""Division of `a` and `b`, implies `__div__`. """
return GMPYRational(a) / GMPYRational(b), self.zero
def numer(self, a):
"""Returns numerator of `a`. """
return a.numerator
def denom(self, a):
"""Returns denominator of `a`. """
return a.denominator
def factorial(self, a):
"""Returns factorial of `a`. """
return GMPYRational(gmpy_factorial(int(a)))
|
66d29ced088ff2edffc27ffadbd937666106d10d0238e831868a240f512c2357
|
"""Implementation of :class:`QuotientRing` class."""
from __future__ import print_function, division
from sympy.polys.agca.modules import FreeModuleQuotientRing
from sympy.polys.domains.ring import Ring
from sympy.polys.polyerrors import NotReversible, CoercionFailed
from sympy.utilities import public
# TODO
# - successive quotients (when quotient ideals are implemented)
# - poly rings over quotients?
# - division by non-units in integral domains?
@public
class QuotientRingElement(object):
"""
Class representing elements of (commutative) quotient rings.
Attributes:
- ring - containing ring
- data - element of ring.ring (i.e. base ring) representing self
"""
def __init__(self, ring, data):
self.ring = ring
self.data = data
def __str__(self):
from sympy import sstr
return sstr(self.data) + " + " + str(self.ring.base_ideal)
def __add__(self, om):
if not isinstance(om, self.__class__) or om.ring != self.ring:
try:
om = self.ring.convert(om)
except (NotImplementedError, CoercionFailed):
return NotImplemented
return self.ring(self.data + om.data)
__radd__ = __add__
def __neg__(self):
return self.ring(self.data*self.ring.ring.convert(-1))
def __sub__(self, om):
return self.__add__(-om)
def __rsub__(self, om):
return (-self).__add__(om)
def __mul__(self, o):
if not isinstance(o, self.__class__):
try:
o = self.ring.convert(o)
except (NotImplementedError, CoercionFailed):
return NotImplemented
return self.ring(self.data*o.data)
__rmul__ = __mul__
def __rdiv__(self, o):
return self.ring.revert(self)*o
__rtruediv__ = __rdiv__
def __div__(self, o):
if not isinstance(o, self.__class__):
try:
o = self.ring.convert(o)
except (NotImplementedError, CoercionFailed):
return NotImplemented
return self.ring.revert(o)*self
__truediv__ = __div__
def __pow__(self, oth):
return self.ring(self.data**oth)
def __eq__(self, om):
if not isinstance(om, self.__class__) or om.ring != self.ring:
return False
return self.ring.is_zero(self - om)
def __ne__(self, om):
return not self == om
class QuotientRing(Ring):
"""
Class representing (commutative) quotient rings.
You should not usually instantiate this by hand, instead use the constructor
from the base ring in the construction.
>>> from sympy.abc import x
>>> from sympy import QQ
>>> I = QQ.old_poly_ring(x).ideal(x**3 + 1)
>>> QQ.old_poly_ring(x).quotient_ring(I)
QQ[x]/<x**3 + 1>
Shorter versions are possible:
>>> QQ.old_poly_ring(x)/I
QQ[x]/<x**3 + 1>
>>> QQ.old_poly_ring(x)/[x**3 + 1]
QQ[x]/<x**3 + 1>
Attributes:
- ring - the base ring
- base_ideal - the ideal used to form the quotient
"""
has_assoc_Ring = True
has_assoc_Field = False
dtype = QuotientRingElement
def __init__(self, ring, ideal):
if not ideal.ring == ring:
raise ValueError('Ideal must belong to %s, got %s' % (ring, ideal))
self.ring = ring
self.base_ideal = ideal
self.zero = self(self.ring.zero)
self.one = self(self.ring.one)
def __str__(self):
return str(self.ring) + "/" + str(self.base_ideal)
def __hash__(self):
return hash((self.__class__.__name__, self.dtype, self.ring, self.base_ideal))
def new(self, a):
"""Construct an element of `self` domain from `a`. """
if not isinstance(a, self.ring.dtype):
a = self.ring(a)
# TODO optionally disable reduction?
return self.dtype(self, self.base_ideal.reduce_element(a))
def __eq__(self, other):
"""Returns `True` if two domains are equivalent. """
return isinstance(other, QuotientRing) and \
self.ring == other.ring and self.base_ideal == other.base_ideal
def from_ZZ_python(K1, a, K0):
"""Convert a Python `int` object to `dtype`. """
return K1(K1.ring.convert(a, K0))
from_QQ_python = from_ZZ_python
from_ZZ_gmpy = from_ZZ_python
from_QQ_gmpy = from_ZZ_python
from_RealField = from_ZZ_python
from_GlobalPolynomialRing = from_ZZ_python
from_FractionField = from_ZZ_python
def from_sympy(self, a):
return self(self.ring.from_sympy(a))
def to_sympy(self, a):
return self.ring.to_sympy(a.data)
def from_QuotientRing(self, a, K0):
if K0 == self:
return a
def poly_ring(self, *gens):
"""Returns a polynomial ring, i.e. `K[X]`. """
raise NotImplementedError('nested domains not allowed')
def frac_field(self, *gens):
"""Returns a fraction field, i.e. `K(X)`. """
raise NotImplementedError('nested domains not allowed')
def revert(self, a):
"""
Compute a**(-1), if possible.
"""
I = self.ring.ideal(a.data) + self.base_ideal
try:
return self(I.in_terms_of_generators(1)[0])
except ValueError: # 1 not in I
raise NotReversible('%s not a unit in %r' % (a, self))
def is_zero(self, a):
return self.base_ideal.contains(a.data)
def free_module(self, rank):
"""
Generate a free module of rank ``rank`` over ``self``.
>>> from sympy.abc import x
>>> from sympy import QQ
>>> (QQ.old_poly_ring(x)/[x**2 + 1]).free_module(2)
(QQ[x]/<x**2 + 1>)**2
"""
return FreeModuleQuotientRing(self, rank)
|
514fae2dffb1c6824edf8ccdd0f34fb06caa036fe6e4cf9d964269bfa7c3f42f
|
"""Implementation of :class:`RealField` class. """
from __future__ import print_function, division
from sympy.core.numbers import Float
from sympy.polys.domains.field import Field
from sympy.polys.domains.simpledomain import SimpleDomain
from sympy.polys.domains.characteristiczero import CharacteristicZero
from sympy.polys.domains.mpelements import MPContext
from sympy.polys.polyerrors import CoercionFailed
from sympy.utilities import public
@public
class RealField(Field, CharacteristicZero, SimpleDomain):
"""Real numbers up to the given precision. """
rep = 'RR'
is_RealField = is_RR = True
is_Exact = False
is_Numerical = True
is_PID = False
has_assoc_Ring = False
has_assoc_Field = True
_default_precision = 53
@property
def has_default_precision(self):
return self.precision == self._default_precision
@property
def precision(self):
return self._context.prec
@property
def dps(self):
return self._context.dps
@property
def tolerance(self):
return self._context.tolerance
def __init__(self, prec=_default_precision, dps=None, tol=None):
context = MPContext(prec, dps, tol)
context._parent = self
self._context = context
self.dtype = context.mpf
self.zero = self.dtype(0)
self.one = self.dtype(1)
def __eq__(self, other):
return (isinstance(other, RealField)
and self.precision == other.precision
and self.tolerance == other.tolerance)
def __hash__(self):
return hash((self.__class__.__name__, self.dtype, self.precision, self.tolerance))
def to_sympy(self, element):
"""Convert ``element`` to SymPy number. """
return Float(element, self.dps)
def from_sympy(self, expr):
"""Convert SymPy's number to ``dtype``. """
number = expr.evalf(n=self.dps)
if number.is_Number:
return self.dtype(number)
else:
raise CoercionFailed("expected real number, got %s" % expr)
def from_ZZ_python(self, element, base):
return self.dtype(element)
def from_QQ_python(self, element, base):
return self.dtype(element.numerator) / element.denominator
def from_ZZ_gmpy(self, element, base):
return self.dtype(int(element))
def from_QQ_gmpy(self, element, base):
return self.dtype(int(element.numerator)) / int(element.denominator)
def from_RealField(self, element, base):
if self == base:
return element
else:
return self.dtype(element)
def from_ComplexField(self, element, base):
if not element.imag:
return self.dtype(element.real)
def to_rational(self, element, limit=True):
"""Convert a real number to rational number. """
return self._context.to_rational(element, limit)
def get_ring(self):
"""Returns a ring associated with ``self``. """
return self
def get_exact(self):
"""Returns an exact domain associated with ``self``. """
from sympy.polys.domains import QQ
return QQ
def gcd(self, a, b):
"""Returns GCD of ``a`` and ``b``. """
return self.one
def lcm(self, a, b):
"""Returns LCM of ``a`` and ``b``. """
return a*b
def almosteq(self, a, b, tolerance=None):
"""Check if ``a`` and ``b`` are almost equal. """
return self._context.almosteq(a, b, tolerance)
|
b65b1985fc4c529c77d356a54701d568c118d117e6d10ed23a1e0157b55a89ce
|
"""Implementation of :class:`Field` class. """
from __future__ import print_function, division
from sympy.polys.domains.ring import Ring
from sympy.polys.polyerrors import NotReversible, DomainError
from sympy.utilities import public
@public
class Field(Ring):
"""Represents a field domain. """
is_Field = True
is_PID = True
def get_ring(self):
"""Returns a ring associated with ``self``. """
raise DomainError('there is no ring associated with %s' % self)
def get_field(self):
"""Returns a field associated with ``self``. """
return self
def exquo(self, a, b):
"""Exact quotient of ``a`` and ``b``, implies ``__div__``. """
return a / b
def quo(self, a, b):
"""Quotient of ``a`` and ``b``, implies ``__div__``. """
return a / b
def rem(self, a, b):
"""Remainder of ``a`` and ``b``, implies nothing. """
return self.zero
def div(self, a, b):
"""Division of ``a`` and ``b``, implies ``__div__``. """
return a / b, self.zero
def gcd(self, a, b):
"""
Returns GCD of ``a`` and ``b``.
This definition of GCD over fields allows to clear denominators
in `primitive()`.
Examples
========
>>> from sympy.polys.domains import QQ
>>> from sympy import S, gcd, primitive
>>> from sympy.abc import x
>>> QQ.gcd(QQ(2, 3), QQ(4, 9))
2/9
>>> gcd(S(2)/3, S(4)/9)
2/9
>>> primitive(2*x/3 + S(4)/9)
(2/9, 3*x + 2)
"""
try:
ring = self.get_ring()
except DomainError:
return self.one
p = ring.gcd(self.numer(a), self.numer(b))
q = ring.lcm(self.denom(a), self.denom(b))
return self.convert(p, ring)/q
def lcm(self, a, b):
"""
Returns LCM of ``a`` and ``b``.
>>> from sympy.polys.domains import QQ
>>> from sympy import S, lcm
>>> QQ.lcm(QQ(2, 3), QQ(4, 9))
4/3
>>> lcm(S(2)/3, S(4)/9)
4/3
"""
try:
ring = self.get_ring()
except DomainError:
return a*b
p = ring.lcm(self.numer(a), self.numer(b))
q = ring.gcd(self.denom(a), self.denom(b))
return self.convert(p, ring)/q
def revert(self, a):
"""Returns ``a**(-1)`` if possible. """
if a:
return 1/a
else:
raise NotReversible('zero is not reversible')
|
49b9f932096ee3f2c4929839aa6f6e62a196c9df184af09891d5f5aaa0d1ae63
|
"""Implementation of :class:`PythonRationalField` class. """
from __future__ import print_function, division
from sympy.polys.domains.groundtypes import PythonInteger, PythonRational, SymPyRational
from sympy.polys.domains.rationalfield import RationalField
from sympy.polys.polyerrors import CoercionFailed
from sympy.utilities import public
@public
class PythonRationalField(RationalField):
"""Rational field based on Python rational number type. """
dtype = PythonRational
zero = dtype(0)
one = dtype(1)
alias = 'QQ_python'
def __init__(self):
pass
def get_ring(self):
"""Returns ring associated with ``self``. """
from sympy.polys.domains import PythonIntegerRing
return PythonIntegerRing()
def to_sympy(self, a):
"""Convert `a` to a SymPy object. """
return SymPyRational(a.numerator, a.denominator)
def from_sympy(self, a):
"""Convert SymPy's Rational to `dtype`. """
if a.is_Rational:
return PythonRational(a.p, a.q)
elif a.is_Float:
from sympy.polys.domains import RR
p, q = RR.to_rational(a)
return PythonRational(int(p), int(q))
else:
raise CoercionFailed("expected `Rational` object, got %s" % a)
def from_ZZ_python(K1, a, K0):
"""Convert a Python `int` object to `dtype`. """
return PythonRational(a)
def from_QQ_python(K1, a, K0):
"""Convert a Python `Fraction` object to `dtype`. """
return a
def from_ZZ_gmpy(K1, a, K0):
"""Convert a GMPY `mpz` object to `dtype`. """
return PythonRational(PythonInteger(a))
def from_QQ_gmpy(K1, a, K0):
"""Convert a GMPY `mpq` object to `dtype`. """
return PythonRational(PythonInteger(a.numer()),
PythonInteger(a.denom()))
def from_RealField(K1, a, K0):
"""Convert a mpmath `mpf` object to `dtype`. """
p, q = K0.to_rational(a)
return PythonRational(int(p), int(q))
def numer(self, a):
"""Returns numerator of `a`. """
return a.numerator
def denom(self, a):
"""Returns denominator of `a`. """
return a.denominator
|
b1ab6f7ae4c510e4f6a99f904a0dc23ef8c4eee9236df00431fd98294aa1927f
|
"""Implementation of :class:`PolynomialRing` class. """
from __future__ import print_function, division
from sympy.core.compatibility import iterable, range
from sympy.polys.agca.modules import FreeModulePolyRing
from sympy.polys.domains.characteristiczero import CharacteristicZero
from sympy.polys.domains.compositedomain import CompositeDomain
from sympy.polys.domains.old_fractionfield import FractionField
from sympy.polys.domains.ring import Ring
from sympy.polys.orderings import monomial_key, build_product_order
from sympy.polys.polyclasses import DMP, DMF
from sympy.polys.polyerrors import (GeneratorsNeeded, PolynomialError,
CoercionFailed, ExactQuotientFailed, NotReversible)
from sympy.polys.polyutils import dict_from_basic, basic_from_dict, _dict_reorder
from sympy.utilities import public
# XXX why does this derive from CharacteristicZero???
@public
class PolynomialRingBase(Ring, CharacteristicZero, CompositeDomain):
"""
Base class for generalized polynomial rings.
This base class should be used for uniform access to generalized polynomial
rings. Subclasses only supply information about the element storage etc.
Do not instantiate.
"""
has_assoc_Ring = True
has_assoc_Field = True
default_order = "grevlex"
def __init__(self, dom, *gens, **opts):
if not gens:
raise GeneratorsNeeded("generators not specified")
lev = len(gens) - 1
self.ngens = len(gens)
self.zero = self.dtype.zero(lev, dom, ring=self)
self.one = self.dtype.one(lev, dom, ring=self)
self.domain = self.dom = dom
self.symbols = self.gens = gens
# NOTE 'order' may not be set if inject was called through CompositeDomain
self.order = opts.get('order', monomial_key(self.default_order))
def new(self, element):
return self.dtype(element, self.dom, len(self.gens) - 1, ring=self)
def __str__(self):
s_order = str(self.order)
orderstr = (
" order=" + s_order) if s_order != self.default_order else ""
return str(self.dom) + '[' + ','.join(map(str, self.gens)) + orderstr + ']'
def __hash__(self):
return hash((self.__class__.__name__, self.dtype, self.dom,
self.gens, self.order))
def __eq__(self, other):
"""Returns `True` if two domains are equivalent. """
return isinstance(other, PolynomialRingBase) and \
self.dtype == other.dtype and self.dom == other.dom and \
self.gens == other.gens and self.order == other.order
def from_ZZ_python(K1, a, K0):
"""Convert a Python `int` object to `dtype`. """
return K1(K1.dom.convert(a, K0))
def from_QQ_python(K1, a, K0):
"""Convert a Python `Fraction` object to `dtype`. """
return K1(K1.dom.convert(a, K0))
def from_ZZ_gmpy(K1, a, K0):
"""Convert a GMPY `mpz` object to `dtype`. """
return K1(K1.dom.convert(a, K0))
def from_QQ_gmpy(K1, a, K0):
"""Convert a GMPY `mpq` object to `dtype`. """
return K1(K1.dom.convert(a, K0))
def from_RealField(K1, a, K0):
"""Convert a mpmath `mpf` object to `dtype`. """
return K1(K1.dom.convert(a, K0))
def from_AlgebraicField(K1, a, K0):
"""Convert a `ANP` object to `dtype`. """
if K1.dom == K0:
return K1(a)
def from_GlobalPolynomialRing(K1, a, K0):
"""Convert a `DMP` object to `dtype`. """
if K1.gens == K0.gens:
if K1.dom == K0.dom:
return K1(a.rep) # set the correct ring
else:
return K1(a.convert(K1.dom).rep)
else:
monoms, coeffs = _dict_reorder(a.to_dict(), K0.gens, K1.gens)
if K1.dom != K0.dom:
coeffs = [ K1.dom.convert(c, K0.dom) for c in coeffs ]
return K1(dict(zip(monoms, coeffs)))
def get_field(self):
"""Returns a field associated with `self`. """
return FractionField(self.dom, *self.gens)
def poly_ring(self, *gens):
"""Returns a polynomial ring, i.e. `K[X]`. """
raise NotImplementedError('nested domains not allowed')
def frac_field(self, *gens):
"""Returns a fraction field, i.e. `K(X)`. """
raise NotImplementedError('nested domains not allowed')
def revert(self, a):
try:
return 1/a
except (ExactQuotientFailed, ZeroDivisionError):
raise NotReversible('%s is not a unit' % a)
def gcdex(self, a, b):
"""Extended GCD of `a` and `b`. """
return a.gcdex(b)
def gcd(self, a, b):
"""Returns GCD of `a` and `b`. """
return a.gcd(b)
def lcm(self, a, b):
"""Returns LCM of `a` and `b`. """
return a.lcm(b)
def factorial(self, a):
"""Returns factorial of `a`. """
return self.dtype(self.dom.factorial(a))
def _vector_to_sdm(self, v, order):
"""
For internal use by the modules class.
Convert an iterable of elements of this ring into a sparse distributed
module element.
"""
raise NotImplementedError
def _sdm_to_dics(self, s, n):
"""Helper for _sdm_to_vector."""
from sympy.polys.distributedmodules import sdm_to_dict
dic = sdm_to_dict(s)
res = [{} for _ in range(n)]
for k, v in dic.items():
res[k[0]][k[1:]] = v
return res
def _sdm_to_vector(self, s, n):
"""
For internal use by the modules class.
Convert a sparse distributed module into a list of length ``n``.
Examples
========
>>> from sympy import QQ, ilex
>>> from sympy.abc import x, y
>>> R = QQ.old_poly_ring(x, y, order=ilex)
>>> L = [((1, 1, 1), QQ(1)), ((0, 1, 0), QQ(1)), ((0, 0, 1), QQ(2))]
>>> R._sdm_to_vector(L, 2)
[x + 2*y, x*y]
"""
dics = self._sdm_to_dics(s, n)
# NOTE this works for global and local rings!
return [self(x) for x in dics]
def free_module(self, rank):
"""
Generate a free module of rank ``rank`` over ``self``.
Examples
========
>>> from sympy.abc import x
>>> from sympy import QQ
>>> QQ.old_poly_ring(x).free_module(2)
QQ[x]**2
"""
return FreeModulePolyRing(self, rank)
def _vector_to_sdm_helper(v, order):
"""Helper method for common code in Global and Local poly rings."""
from sympy.polys.distributedmodules import sdm_from_dict
d = {}
for i, e in enumerate(v):
for key, value in e.to_dict().items():
d[(i,) + key] = value
return sdm_from_dict(d, order)
@public
class GlobalPolynomialRing(PolynomialRingBase):
"""A true polynomial ring, with objects DMP. """
is_PolynomialRing = is_Poly = True
dtype = DMP
def from_FractionField(K1, a, K0):
"""
Convert a ``DMF`` object to ``DMP``.
Examples
========
>>> from sympy.polys.polyclasses import DMP, DMF
>>> from sympy.polys.domains import ZZ
>>> from sympy.abc import x
>>> f = DMF(([ZZ(1), ZZ(1)], [ZZ(1)]), ZZ)
>>> K = ZZ.old_frac_field(x)
>>> F = ZZ.old_poly_ring(x).from_FractionField(f, K)
>>> F == DMP([ZZ(1), ZZ(1)], ZZ)
True
>>> type(F)
<class 'sympy.polys.polyclasses.DMP'>
"""
if a.denom().is_one:
return K1.from_GlobalPolynomialRing(a.numer(), K0)
def to_sympy(self, a):
"""Convert `a` to a SymPy object. """
return basic_from_dict(a.to_sympy_dict(), *self.gens)
def from_sympy(self, a):
"""Convert SymPy's expression to `dtype`. """
try:
rep, _ = dict_from_basic(a, gens=self.gens)
except PolynomialError:
raise CoercionFailed("can't convert %s to type %s" % (a, self))
for k, v in rep.items():
rep[k] = self.dom.from_sympy(v)
return self(rep)
def is_positive(self, a):
"""Returns True if `LC(a)` is positive. """
return self.dom.is_positive(a.LC())
def is_negative(self, a):
"""Returns True if `LC(a)` is negative. """
return self.dom.is_negative(a.LC())
def is_nonpositive(self, a):
"""Returns True if `LC(a)` is non-positive. """
return self.dom.is_nonpositive(a.LC())
def is_nonnegative(self, a):
"""Returns True if `LC(a)` is non-negative. """
return self.dom.is_nonnegative(a.LC())
def _vector_to_sdm(self, v, order):
"""
Examples
========
>>> from sympy import lex, QQ
>>> from sympy.abc import x, y
>>> R = QQ.old_poly_ring(x, y)
>>> f = R.convert(x + 2*y)
>>> g = R.convert(x * y)
>>> R._vector_to_sdm([f, g], lex)
[((1, 1, 1), 1), ((0, 1, 0), 1), ((0, 0, 1), 2)]
"""
return _vector_to_sdm_helper(v, order)
class GeneralizedPolynomialRing(PolynomialRingBase):
"""A generalized polynomial ring, with objects DMF. """
dtype = DMF
def new(self, a):
"""Construct an element of `self` domain from `a`. """
res = self.dtype(a, self.dom, len(self.gens) - 1, ring=self)
# make sure res is actually in our ring
if res.denom().terms(order=self.order)[0][0] != (0,)*len(self.gens):
from sympy.printing.str import sstr
raise CoercionFailed("denominator %s not allowed in %s"
% (sstr(res), self))
return res
def __contains__(self, a):
try:
a = self.convert(a)
except CoercionFailed:
return False
return a.denom().terms(order=self.order)[0][0] == (0,)*len(self.gens)
def from_FractionField(K1, a, K0):
dmf = K1.get_field().from_FractionField(a, K0)
return K1((dmf.num, dmf.den))
def to_sympy(self, a):
"""Convert `a` to a SymPy object. """
return (basic_from_dict(a.numer().to_sympy_dict(), *self.gens) /
basic_from_dict(a.denom().to_sympy_dict(), *self.gens))
def from_sympy(self, a):
"""Convert SymPy's expression to `dtype`. """
p, q = a.as_numer_denom()
num, _ = dict_from_basic(p, gens=self.gens)
den, _ = dict_from_basic(q, gens=self.gens)
for k, v in num.items():
num[k] = self.dom.from_sympy(v)
for k, v in den.items():
den[k] = self.dom.from_sympy(v)
return self((num, den)).cancel()
def _vector_to_sdm(self, v, order):
"""
Turn an iterable into a sparse distributed module.
Note that the vector is multiplied by a unit first to make all entries
polynomials.
Examples
========
>>> from sympy import ilex, QQ
>>> from sympy.abc import x, y
>>> R = QQ.old_poly_ring(x, y, order=ilex)
>>> f = R.convert((x + 2*y) / (1 + x))
>>> g = R.convert(x * y)
>>> R._vector_to_sdm([f, g], ilex)
[((0, 0, 1), 2), ((0, 1, 0), 1), ((1, 1, 1), 1), ((1,
2, 1), 1)]
"""
# NOTE this is quite inefficient...
u = self.one.numer()
for x in v:
u *= x.denom()
return _vector_to_sdm_helper([x.numer()*u/x.denom() for x in v], order)
@public
def PolynomialRing(dom, *gens, **opts):
r"""
Create a generalized multivariate polynomial ring.
A generalized polynomial ring is defined by a ground field `K`, a set
of generators (typically `x_1, \ldots, x_n`) and a monomial order `<`.
The monomial order can be global, local or mixed. In any case it induces
a total ordering on the monomials, and there exists for every (non-zero)
polynomial `f \in K[x_1, \ldots, x_n]` a well-defined "leading monomial"
`LM(f) = LM(f, >)`. One can then define a multiplicative subset
`S = S_> = \{f \in K[x_1, \ldots, x_n] | LM(f) = 1\}`. The generalized
polynomial ring corresponding to the monomial order is
`R = S^{-1}K[x_1, \ldots, x_n]`.
If `>` is a so-called global order, that is `1` is the smallest monomial,
then we just have `S = K` and `R = K[x_1, \ldots, x_n]`.
Examples
========
A few examples may make this clearer.
>>> from sympy.abc import x, y
>>> from sympy import QQ
Our first ring uses global lexicographic order.
>>> R1 = QQ.old_poly_ring(x, y, order=(("lex", x, y),))
The second ring uses local lexicographic order. Note that when using a
single (non-product) order, you can just specify the name and omit the
variables:
>>> R2 = QQ.old_poly_ring(x, y, order="ilex")
The third and fourth rings use a mixed orders:
>>> o1 = (("ilex", x), ("lex", y))
>>> o2 = (("lex", x), ("ilex", y))
>>> R3 = QQ.old_poly_ring(x, y, order=o1)
>>> R4 = QQ.old_poly_ring(x, y, order=o2)
We will investigate what elements of `K(x, y)` are contained in the various
rings.
>>> L = [x, 1/x, y/(1 + x), 1/(1 + y), 1/(1 + x*y)]
>>> test = lambda R: [f in R for f in L]
The first ring is just `K[x, y]`:
>>> test(R1)
[True, False, False, False, False]
The second ring is R1 localised at the maximal ideal (x, y):
>>> test(R2)
[True, False, True, True, True]
The third ring is R1 localised at the prime ideal (x):
>>> test(R3)
[True, False, True, False, True]
Finally the fourth ring is R1 localised at `S = K[x, y] \setminus yK[y]`:
>>> test(R4)
[True, False, False, True, False]
"""
order = opts.get("order", GeneralizedPolynomialRing.default_order)
if iterable(order):
order = build_product_order(order, gens)
order = monomial_key(order)
opts['order'] = order
if order.is_global:
return GlobalPolynomialRing(dom, *gens, **opts)
else:
return GeneralizedPolynomialRing(dom, *gens, **opts)
|
79ab01db45ec2c943b48666a54cabbc7ebe94cc31ec2081493799ac94b0a4645
|
"""Implementation of :class:`IntegerRing` class. """
from __future__ import print_function, division
from sympy.polys.domains.characteristiczero import CharacteristicZero
from sympy.polys.domains.ring import Ring
from sympy.polys.domains.simpledomain import SimpleDomain
from sympy.utilities import public
import math
@public
class IntegerRing(Ring, CharacteristicZero, SimpleDomain):
"""General class for integer rings. """
rep = 'ZZ'
is_IntegerRing = is_ZZ = True
is_Numerical = True
is_PID = True
has_assoc_Ring = True
has_assoc_Field = True
def get_field(self):
"""Returns a field associated with ``self``. """
from sympy.polys.domains import QQ
return QQ
def algebraic_field(self, *extension):
r"""Returns an algebraic field, i.e. `\mathbb{Q}(\alpha, \ldots)`. """
return self.get_field().algebraic_field(*extension)
def from_AlgebraicField(K1, a, K0):
"""Convert a ``ANP`` object to ``dtype``. """
if a.is_ground:
return K1.convert(a.LC(), K0.dom)
def log(self, a, b):
"""Returns b-base logarithm of ``a``. """
return self.dtype(math.log(int(a), b))
|
cc5b0f59560420a047e27d1e296bddfa57686df24076a0434112af33a67e2837
|
"""Implementation of :class:`ComplexField` class. """
from __future__ import print_function, division
from sympy.core.numbers import Float, I
from sympy.polys.domains.characteristiczero import CharacteristicZero
from sympy.polys.domains.field import Field
from sympy.polys.domains.mpelements import MPContext
from sympy.polys.domains.simpledomain import SimpleDomain
from sympy.polys.polyerrors import DomainError, CoercionFailed
from sympy.utilities import public
@public
class ComplexField(Field, CharacteristicZero, SimpleDomain):
"""Complex numbers up to the given precision. """
rep = 'CC'
is_ComplexField = is_CC = True
is_Exact = False
is_Numerical = True
has_assoc_Ring = False
has_assoc_Field = True
_default_precision = 53
@property
def has_default_precision(self):
return self.precision == self._default_precision
@property
def precision(self):
return self._context.prec
@property
def dps(self):
return self._context.dps
@property
def tolerance(self):
return self._context.tolerance
def __init__(self, prec=_default_precision, dps=None, tol=None):
context = MPContext(prec, dps, tol)
context._parent = self
self._context = context
self.dtype = context.mpc
self.zero = self.dtype(0)
self.one = self.dtype(1)
def __eq__(self, other):
return (isinstance(other, ComplexField)
and self.precision == other.precision
and self.tolerance == other.tolerance)
def __hash__(self):
return hash((self.__class__.__name__, self.dtype, self.precision, self.tolerance))
def to_sympy(self, element):
"""Convert ``element`` to SymPy number. """
return Float(element.real, self.dps) + I*Float(element.imag, self.dps)
def from_sympy(self, expr):
"""Convert SymPy's number to ``dtype``. """
number = expr.evalf(n=self.dps)
real, imag = number.as_real_imag()
if real.is_Number and imag.is_Number:
return self.dtype(real, imag)
else:
raise CoercionFailed("expected complex number, got %s" % expr)
def from_ZZ_python(self, element, base):
return self.dtype(element)
def from_QQ_python(self, element, base):
return self.dtype(element.numerator) / element.denominator
def from_ZZ_gmpy(self, element, base):
return self.dtype(int(element))
def from_QQ_gmpy(self, element, base):
return self.dtype(int(element.numerator)) / int(element.denominator)
def from_RealField(self, element, base):
return self.dtype(element)
def from_ComplexField(self, element, base):
if self == base:
return element
else:
return self.dtype(element)
def get_ring(self):
"""Returns a ring associated with ``self``. """
raise DomainError("there is no ring associated with %s" % self)
def get_exact(self):
"""Returns an exact domain associated with ``self``. """
raise DomainError("there is no exact domain associated with %s" % self)
def gcd(self, a, b):
"""Returns GCD of ``a`` and ``b``. """
return self.one
def lcm(self, a, b):
"""Returns LCM of ``a`` and ``b``. """
return a*b
def almosteq(self, a, b, tolerance=None):
"""Check if ``a`` and ``b`` are almost equal. """
return self._context.almosteq(a, b, tolerance)
|
58e4ed1647d4f0c46523219bd4b30d4f3c4792aef8cdc887e6bf7cc55df59d21
|
"""Implementation of :class:`FractionField` class. """
from __future__ import print_function, division
from sympy.polys.domains.compositedomain import CompositeDomain
from sympy.polys.domains.field import Field
from sympy.polys.polyerrors import CoercionFailed, GeneratorsError
from sympy.utilities import public
@public
class FractionField(Field, CompositeDomain):
"""A class for representing multivariate rational function fields. """
is_FractionField = is_Frac = True
has_assoc_Ring = True
has_assoc_Field = True
def __init__(self, domain_or_field, symbols=None, order=None):
from sympy.polys.fields import FracField
if isinstance(domain_or_field, FracField) and symbols is None and order is None:
field = domain_or_field
else:
field = FracField(symbols, domain_or_field, order)
self.field = field
self.dtype = field.dtype
self.gens = field.gens
self.ngens = field.ngens
self.symbols = field.symbols
self.domain = field.domain
# TODO: remove this
self.dom = self.domain
def new(self, element):
return self.field.field_new(element)
@property
def zero(self):
return self.field.zero
@property
def one(self):
return self.field.one
@property
def order(self):
return self.field.order
def __str__(self):
return str(self.domain) + '(' + ','.join(map(str, self.symbols)) + ')'
def __hash__(self):
return hash((self.__class__.__name__, self.dtype.field, self.domain, self.symbols))
def __eq__(self, other):
"""Returns `True` if two domains are equivalent. """
return isinstance(other, FractionField) and \
(self.dtype.field, self.domain, self.symbols) ==\
(other.dtype.field, other.domain, other.symbols)
def to_sympy(self, a):
"""Convert `a` to a SymPy object. """
return a.as_expr()
def from_sympy(self, a):
"""Convert SymPy's expression to `dtype`. """
return self.field.from_expr(a)
def from_ZZ_python(K1, a, K0):
"""Convert a Python `int` object to `dtype`. """
return K1(K1.domain.convert(a, K0))
def from_QQ_python(K1, a, K0):
"""Convert a Python `Fraction` object to `dtype`. """
return K1(K1.domain.convert(a, K0))
def from_ZZ_gmpy(K1, a, K0):
"""Convert a GMPY `mpz` object to `dtype`. """
return K1(K1.domain.convert(a, K0))
def from_QQ_gmpy(K1, a, K0):
"""Convert a GMPY `mpq` object to `dtype`. """
return K1(K1.domain.convert(a, K0))
def from_RealField(K1, a, K0):
"""Convert a mpmath `mpf` object to `dtype`. """
return K1(K1.domain.convert(a, K0))
def from_AlgebraicField(K1, a, K0):
"""Convert an algebraic number to ``dtype``. """
if K1.domain == K0:
return K1.new(a)
def from_PolynomialRing(K1, a, K0):
"""Convert a polynomial to ``dtype``. """
try:
return K1.new(a)
except (CoercionFailed, GeneratorsError):
return None
def from_FractionField(K1, a, K0):
"""Convert a rational function to ``dtype``. """
try:
return a.set_field(K1.field)
except (CoercionFailed, GeneratorsError):
return None
def get_ring(self):
"""Returns a field associated with `self`. """
return self.field.to_ring().to_domain()
def is_positive(self, a):
"""Returns True if `LC(a)` is positive. """
return self.domain.is_positive(a.numer.LC)
def is_negative(self, a):
"""Returns True if `LC(a)` is negative. """
return self.domain.is_negative(a.numer.LC)
def is_nonpositive(self, a):
"""Returns True if `LC(a)` is non-positive. """
return self.domain.is_nonpositive(a.numer.LC)
def is_nonnegative(self, a):
"""Returns True if `LC(a)` is non-negative. """
return self.domain.is_nonnegative(a.numer.LC)
def numer(self, a):
"""Returns numerator of ``a``. """
return a.numer
def denom(self, a):
"""Returns denominator of ``a``. """
return a.denom
def factorial(self, a):
"""Returns factorial of `a`. """
return self.dtype(self.domain.factorial(a))
|
52acd90a60395c648db5e984390367d075159727f194ef5ca4fdbc98a399bd45
|
"""Implementation of :class:`ExpressionDomain` class. """
from __future__ import print_function, division
from sympy.core import sympify, SympifyError
from sympy.polys.domains.characteristiczero import CharacteristicZero
from sympy.polys.domains.field import Field
from sympy.polys.domains.simpledomain import SimpleDomain
from sympy.polys.polyutils import PicklableWithSlots
from sympy.utilities import public
@public
class ExpressionDomain(Field, CharacteristicZero, SimpleDomain):
"""A class for arbitrary expressions. """
is_SymbolicDomain = is_EX = True
class Expression(PicklableWithSlots):
"""An arbitrary expression. """
__slots__ = ['ex']
def __init__(self, ex):
if not isinstance(ex, self.__class__):
self.ex = sympify(ex)
else:
self.ex = ex.ex
def __repr__(f):
return 'EX(%s)' % repr(f.ex)
def __str__(f):
return 'EX(%s)' % str(f.ex)
def __hash__(self):
return hash((self.__class__.__name__, self.ex))
def as_expr(f):
return f.ex
def numer(f):
return f.__class__(f.ex.as_numer_denom()[0])
def denom(f):
return f.__class__(f.ex.as_numer_denom()[1])
def simplify(f, ex):
return f.__class__(ex.cancel())
def __abs__(f):
return f.__class__(abs(f.ex))
def __neg__(f):
return f.__class__(-f.ex)
def _to_ex(f, g):
try:
return f.__class__(g)
except SympifyError:
return None
def __add__(f, g):
g = f._to_ex(g)
if g is not None:
return f.simplify(f.ex + g.ex)
else:
return NotImplemented
def __radd__(f, g):
return f.simplify(f.__class__(g).ex + f.ex)
def __sub__(f, g):
g = f._to_ex(g)
if g is not None:
return f.simplify(f.ex - g.ex)
else:
return NotImplemented
def __rsub__(f, g):
return f.simplify(f.__class__(g).ex - f.ex)
def __mul__(f, g):
g = f._to_ex(g)
if g is not None:
return f.simplify(f.ex*g.ex)
else:
return NotImplemented
def __rmul__(f, g):
return f.simplify(f.__class__(g).ex*f.ex)
def __pow__(f, n):
n = f._to_ex(n)
if n is not None:
return f.simplify(f.ex**n.ex)
else:
return NotImplemented
def __truediv__(f, g):
g = f._to_ex(g)
if g is not None:
return f.simplify(f.ex/g.ex)
else:
return NotImplemented
def __rtruediv__(f, g):
return f.simplify(f.__class__(g).ex/f.ex)
__div__ = __truediv__
__rdiv__ = __rtruediv__
def __eq__(f, g):
return f.ex == f.__class__(g).ex
def __ne__(f, g):
return not f == g
def __nonzero__(f):
return f.ex != 0
__bool__ = __nonzero__
def gcd(f, g):
from sympy.polys import gcd
return f.__class__(gcd(f.ex, f.__class__(g).ex))
def lcm(f, g):
from sympy.polys import lcm
return f.__class__(lcm(f.ex, f.__class__(g).ex))
dtype = Expression
zero = Expression(0)
one = Expression(1)
rep = 'EX'
has_assoc_Ring = False
has_assoc_Field = True
def __init__(self):
pass
def to_sympy(self, a):
"""Convert ``a`` to a SymPy object. """
return a.as_expr()
def from_sympy(self, a):
"""Convert SymPy's expression to ``dtype``. """
return self.dtype(a)
def from_ZZ_python(K1, a, K0):
"""Convert a Python ``int`` object to ``dtype``. """
return K1(K0.to_sympy(a))
def from_QQ_python(K1, a, K0):
"""Convert a Python ``Fraction`` object to ``dtype``. """
return K1(K0.to_sympy(a))
def from_ZZ_gmpy(K1, a, K0):
"""Convert a GMPY ``mpz`` object to ``dtype``. """
return K1(K0.to_sympy(a))
def from_QQ_gmpy(K1, a, K0):
"""Convert a GMPY ``mpq`` object to ``dtype``. """
return K1(K0.to_sympy(a))
def from_RealField(K1, a, K0):
"""Convert a mpmath ``mpf`` object to ``dtype``. """
return K1(K0.to_sympy(a))
def from_PolynomialRing(K1, a, K0):
"""Convert a ``DMP`` object to ``dtype``. """
return K1(K0.to_sympy(a))
def from_FractionField(K1, a, K0):
"""Convert a ``DMF`` object to ``dtype``. """
return K1(K0.to_sympy(a))
def from_ExpressionDomain(K1, a, K0):
"""Convert a ``EX`` object to ``dtype``. """
return a
def get_ring(self):
"""Returns a ring associated with ``self``. """
return self # XXX: EX is not a ring but we don't have much choice here.
def get_field(self):
"""Returns a field associated with ``self``. """
return self
def is_positive(self, a):
"""Returns True if ``a`` is positive. """
return a.ex.as_coeff_mul()[0].is_positive
def is_negative(self, a):
"""Returns True if ``a`` is negative. """
return a.ex.as_coeff_mul()[0].is_negative
def is_nonpositive(self, a):
"""Returns True if ``a`` is non-positive. """
return a.ex.as_coeff_mul()[0].is_nonpositive
def is_nonnegative(self, a):
"""Returns True if ``a`` is non-negative. """
return a.ex.as_coeff_mul()[0].is_nonnegative
def numer(self, a):
"""Returns numerator of ``a``. """
return a.numer()
def denom(self, a):
"""Returns denominator of ``a``. """
return a.denom()
def gcd(self, a, b):
return a.gcd(b)
def lcm(self, a, b):
return a.lcm(b)
|
360608b316f2dab40826eac29071c065f9816901d30a8b1bbeca0baa2f0b7a62
|
"""Implementation of :class:`FractionField` class. """
from __future__ import print_function, division
from sympy.polys.domains.field import Field
from sympy.polys.domains.compositedomain import CompositeDomain
from sympy.polys.domains.characteristiczero import CharacteristicZero
from sympy.polys.polyclasses import DMF
from sympy.polys.polyerrors import GeneratorsNeeded
from sympy.polys.polyutils import dict_from_basic, basic_from_dict, _dict_reorder
from sympy.utilities import public
@public
class FractionField(Field, CharacteristicZero, CompositeDomain):
"""A class for representing rational function fields. """
dtype = DMF
is_FractionField = is_Frac = True
has_assoc_Ring = True
has_assoc_Field = True
def __init__(self, dom, *gens):
if not gens:
raise GeneratorsNeeded("generators not specified")
lev = len(gens) - 1
self.ngens = len(gens)
self.zero = self.dtype.zero(lev, dom, ring=self)
self.one = self.dtype.one(lev, dom, ring=self)
self.domain = self.dom = dom
self.symbols = self.gens = gens
def new(self, element):
return self.dtype(element, self.dom, len(self.gens) - 1, ring=self)
def __str__(self):
return str(self.dom) + '(' + ','.join(map(str, self.gens)) + ')'
def __hash__(self):
return hash((self.__class__.__name__, self.dtype, self.dom, self.gens))
def __eq__(self, other):
"""Returns ``True`` if two domains are equivalent. """
return isinstance(other, FractionField) and \
self.dtype == other.dtype and self.dom == other.dom and self.gens == other.gens
def to_sympy(self, a):
"""Convert ``a`` to a SymPy object. """
return (basic_from_dict(a.numer().to_sympy_dict(), *self.gens) /
basic_from_dict(a.denom().to_sympy_dict(), *self.gens))
def from_sympy(self, a):
"""Convert SymPy's expression to ``dtype``. """
p, q = a.as_numer_denom()
num, _ = dict_from_basic(p, gens=self.gens)
den, _ = dict_from_basic(q, gens=self.gens)
for k, v in num.items():
num[k] = self.dom.from_sympy(v)
for k, v in den.items():
den[k] = self.dom.from_sympy(v)
return self((num, den)).cancel()
def from_ZZ_python(K1, a, K0):
"""Convert a Python ``int`` object to ``dtype``. """
return K1(K1.dom.convert(a, K0))
def from_QQ_python(K1, a, K0):
"""Convert a Python ``Fraction`` object to ``dtype``. """
return K1(K1.dom.convert(a, K0))
def from_ZZ_gmpy(K1, a, K0):
"""Convert a GMPY ``mpz`` object to ``dtype``. """
return K1(K1.dom.convert(a, K0))
def from_QQ_gmpy(K1, a, K0):
"""Convert a GMPY ``mpq`` object to ``dtype``. """
return K1(K1.dom.convert(a, K0))
def from_RealField(K1, a, K0):
"""Convert a mpmath ``mpf`` object to ``dtype``. """
return K1(K1.dom.convert(a, K0))
def from_GlobalPolynomialRing(K1, a, K0):
"""Convert a ``DMF`` object to ``dtype``. """
if K1.gens == K0.gens:
if K1.dom == K0.dom:
return K1(a.rep)
else:
return K1(a.convert(K1.dom).rep)
else:
monoms, coeffs = _dict_reorder(a.to_dict(), K0.gens, K1.gens)
if K1.dom != K0.dom:
coeffs = [ K1.dom.convert(c, K0.dom) for c in coeffs ]
return K1(dict(zip(monoms, coeffs)))
def from_FractionField(K1, a, K0):
"""
Convert a fraction field element to another fraction field.
Examples
========
>>> from sympy.polys.polyclasses import DMF
>>> from sympy.polys.domains import ZZ, QQ
>>> from sympy.abc import x
>>> f = DMF(([ZZ(1), ZZ(2)], [ZZ(1), ZZ(1)]), ZZ)
>>> QQx = QQ.old_frac_field(x)
>>> ZZx = ZZ.old_frac_field(x)
>>> QQx.from_FractionField(f, ZZx)
(x + 2)/(x + 1)
"""
if K1.gens == K0.gens:
if K1.dom == K0.dom:
return a
else:
return K1((a.numer().convert(K1.dom).rep,
a.denom().convert(K1.dom).rep))
elif set(K0.gens).issubset(K1.gens):
nmonoms, ncoeffs = _dict_reorder(
a.numer().to_dict(), K0.gens, K1.gens)
dmonoms, dcoeffs = _dict_reorder(
a.denom().to_dict(), K0.gens, K1.gens)
if K1.dom != K0.dom:
ncoeffs = [ K1.dom.convert(c, K0.dom) for c in ncoeffs ]
dcoeffs = [ K1.dom.convert(c, K0.dom) for c in dcoeffs ]
return K1((dict(zip(nmonoms, ncoeffs)), dict(zip(dmonoms, dcoeffs))))
def get_ring(self):
"""Returns a ring associated with ``self``. """
from sympy.polys.domains import PolynomialRing
return PolynomialRing(self.dom, *self.gens)
def poly_ring(self, *gens):
"""Returns a polynomial ring, i.e. `K[X]`. """
raise NotImplementedError('nested domains not allowed')
def frac_field(self, *gens):
"""Returns a fraction field, i.e. `K(X)`. """
raise NotImplementedError('nested domains not allowed')
def is_positive(self, a):
"""Returns True if ``a`` is positive. """
return self.dom.is_positive(a.numer().LC())
def is_negative(self, a):
"""Returns True if ``a`` is negative. """
return self.dom.is_negative(a.numer().LC())
def is_nonpositive(self, a):
"""Returns True if ``a`` is non-positive. """
return self.dom.is_nonpositive(a.numer().LC())
def is_nonnegative(self, a):
"""Returns True if ``a`` is non-negative. """
return self.dom.is_nonnegative(a.numer().LC())
def numer(self, a):
"""Returns numerator of ``a``. """
return a.numer()
def denom(self, a):
"""Returns denominator of ``a``. """
return a.denom()
def factorial(self, a):
"""Returns factorial of ``a``. """
return self.dtype(self.dom.factorial(a))
|
59e46a84061985cdd2a7f13d5486d2b9a8901840c486f37b1716563fdb10fba8
|
"""Implementaton of :class:`GMPYIntegerRing` class. """
from __future__ import print_function, division
from sympy.polys.domains.groundtypes import (
GMPYInteger, SymPyInteger,
gmpy_factorial,
gmpy_gcdex, gmpy_gcd, gmpy_lcm, gmpy_sqrt,
)
from sympy.polys.domains.integerring import IntegerRing
from sympy.polys.polyerrors import CoercionFailed
from sympy.utilities import public
@public
class GMPYIntegerRing(IntegerRing):
"""Integer ring based on GMPY's ``mpz`` type. """
dtype = GMPYInteger
zero = dtype(0)
one = dtype(1)
tp = type(one)
alias = 'ZZ_gmpy'
def __init__(self):
"""Allow instantiation of this domain. """
def to_sympy(self, a):
"""Convert ``a`` to a SymPy object. """
return SymPyInteger(int(a))
def from_sympy(self, a):
"""Convert SymPy's Integer to ``dtype``. """
if a.is_Integer:
return GMPYInteger(a.p)
elif a.is_Float and int(a) == a:
return GMPYInteger(int(a))
else:
raise CoercionFailed("expected an integer, got %s" % a)
def from_FF_python(K1, a, K0):
"""Convert ``ModularInteger(int)`` to GMPY's ``mpz``. """
return GMPYInteger(a.to_int())
def from_ZZ_python(K1, a, K0):
"""Convert Python's ``int`` to GMPY's ``mpz``. """
return GMPYInteger(a)
def from_QQ_python(K1, a, K0):
"""Convert Python's ``Fraction`` to GMPY's ``mpz``. """
if a.denominator == 1:
return GMPYInteger(a.numerator)
def from_FF_gmpy(K1, a, K0):
"""Convert ``ModularInteger(mpz)`` to GMPY's ``mpz``. """
return a.to_int()
def from_ZZ_gmpy(K1, a, K0):
"""Convert GMPY's ``mpz`` to GMPY's ``mpz``. """
return a
def from_QQ_gmpy(K1, a, K0):
"""Convert GMPY ``mpq`` to GMPY's ``mpz``. """
if a.denominator == 1:
return a.numerator
def from_RealField(K1, a, K0):
"""Convert mpmath's ``mpf`` to GMPY's ``mpz``. """
p, q = K0.to_rational(a)
if q == 1:
return GMPYInteger(p)
def gcdex(self, a, b):
"""Compute extended GCD of ``a`` and ``b``. """
h, s, t = gmpy_gcdex(a, b)
return s, t, h
def gcd(self, a, b):
"""Compute GCD of ``a`` and ``b``. """
return gmpy_gcd(a, b)
def lcm(self, a, b):
"""Compute LCM of ``a`` and ``b``. """
return gmpy_lcm(a, b)
def sqrt(self, a):
"""Compute square root of ``a``. """
return gmpy_sqrt(a)
def factorial(self, a):
"""Compute factorial of ``a``. """
return gmpy_factorial(a)
|
e42a000d7586a7ca871120e041b822efa88c03e82d93ab35f26d13980dc4e8f1
|
"""Implementation of :class:`Domain` class. """
from __future__ import print_function, division
from sympy.core import Basic, sympify
from sympy.core.compatibility import HAS_GMPY, integer_types, is_sequence
from sympy.core.decorators import deprecated
from sympy.polys.domains.domainelement import DomainElement
from sympy.polys.orderings import lex
from sympy.polys.polyerrors import UnificationFailed, CoercionFailed, DomainError
from sympy.polys.polyutils import _unify_gens
from sympy.utilities import default_sort_key, public
@public
class Domain(object):
"""Represents an abstract domain. """
dtype = None
zero = None
one = None
is_Ring = False
is_Field = False
has_assoc_Ring = False
has_assoc_Field = False
is_FiniteField = is_FF = False
is_IntegerRing = is_ZZ = False
is_RationalField = is_QQ = False
is_RealField = is_RR = False
is_ComplexField = is_CC = False
is_AlgebraicField = is_Algebraic = False
is_PolynomialRing = is_Poly = False
is_FractionField = is_Frac = False
is_SymbolicDomain = is_EX = False
is_Exact = True
is_Numerical = False
is_Simple = False
is_Composite = False
is_PID = False
has_CharacteristicZero = False
rep = None
alias = None
@property
@deprecated(useinstead="is_Field", issue=12723, deprecated_since_version="1.1")
def has_Field(self):
return self.is_Field
@property
@deprecated(useinstead="is_Ring", issue=12723, deprecated_since_version="1.1")
def has_Ring(self):
return self.is_Ring
def __init__(self):
raise NotImplementedError
def __str__(self):
return self.rep
def __repr__(self):
return str(self)
def __hash__(self):
return hash((self.__class__.__name__, self.dtype))
def new(self, *args):
return self.dtype(*args)
@property
def tp(self):
return self.dtype
def __call__(self, *args):
"""Construct an element of ``self`` domain from ``args``. """
return self.new(*args)
def normal(self, *args):
return self.dtype(*args)
def convert_from(self, element, base):
"""Convert ``element`` to ``self.dtype`` given the base domain. """
if base.alias is not None:
method = "from_" + base.alias
else:
method = "from_" + base.__class__.__name__
_convert = getattr(self, method)
if _convert is not None:
result = _convert(element, base)
if result is not None:
return result
raise CoercionFailed("can't convert %s of type %s from %s to %s" % (element, type(element), base, self))
def convert(self, element, base=None):
"""Convert ``element`` to ``self.dtype``. """
if base is not None:
return self.convert_from(element, base)
if self.of_type(element):
return element
from sympy.polys.domains import PythonIntegerRing, GMPYIntegerRing, GMPYRationalField, RealField, ComplexField
if isinstance(element, integer_types):
return self.convert_from(element, PythonIntegerRing())
if HAS_GMPY:
integers = GMPYIntegerRing()
if isinstance(element, integers.tp):
return self.convert_from(element, integers)
rationals = GMPYRationalField()
if isinstance(element, rationals.tp):
return self.convert_from(element, rationals)
if isinstance(element, float):
parent = RealField(tol=False)
return self.convert_from(parent(element), parent)
if isinstance(element, complex):
parent = ComplexField(tol=False)
return self.convert_from(parent(element), parent)
if isinstance(element, DomainElement):
return self.convert_from(element, element.parent())
# TODO: implement this in from_ methods
if self.is_Numerical and getattr(element, 'is_ground', False):
return self.convert(element.LC())
if isinstance(element, Basic):
try:
return self.from_sympy(element)
except (TypeError, ValueError):
pass
else: # TODO: remove this branch
if not is_sequence(element):
try:
element = sympify(element)
if isinstance(element, Basic):
return self.from_sympy(element)
except (TypeError, ValueError):
pass
raise CoercionFailed("can't convert %s of type %s to %s" % (element, type(element), self))
def of_type(self, element):
"""Check if ``a`` is of type ``dtype``. """
return isinstance(element, self.tp) # XXX: this isn't correct, e.g. PolyElement
def __contains__(self, a):
"""Check if ``a`` belongs to this domain. """
try:
self.convert(a)
except CoercionFailed:
return False
return True
def to_sympy(self, a):
"""Convert ``a`` to a SymPy object. """
raise NotImplementedError
def from_sympy(self, a):
"""Convert a SymPy object to ``dtype``. """
raise NotImplementedError
def from_FF_python(K1, a, K0):
"""Convert ``ModularInteger(int)`` to ``dtype``. """
return None
def from_ZZ_python(K1, a, K0):
"""Convert a Python ``int`` object to ``dtype``. """
return None
def from_QQ_python(K1, a, K0):
"""Convert a Python ``Fraction`` object to ``dtype``. """
return None
def from_FF_gmpy(K1, a, K0):
"""Convert ``ModularInteger(mpz)`` to ``dtype``. """
return None
def from_ZZ_gmpy(K1, a, K0):
"""Convert a GMPY ``mpz`` object to ``dtype``. """
return None
def from_QQ_gmpy(K1, a, K0):
"""Convert a GMPY ``mpq`` object to ``dtype``. """
return None
def from_RealField(K1, a, K0):
"""Convert a real element object to ``dtype``. """
return None
def from_ComplexField(K1, a, K0):
"""Convert a complex element to ``dtype``. """
return None
def from_AlgebraicField(K1, a, K0):
"""Convert an algebraic number to ``dtype``. """
return None
def from_PolynomialRing(K1, a, K0):
"""Convert a polynomial to ``dtype``. """
if a.is_ground:
return K1.convert(a.LC, K0.dom)
def from_FractionField(K1, a, K0):
"""Convert a rational function to ``dtype``. """
return None
def from_ExpressionDomain(K1, a, K0):
"""Convert a ``EX`` object to ``dtype``. """
return K1.from_sympy(a.ex)
def from_GlobalPolynomialRing(K1, a, K0):
"""Convert a polynomial to ``dtype``. """
if a.degree() <= 0:
return K1.convert(a.LC(), K0.dom)
def from_GeneralizedPolynomialRing(K1, a, K0):
return K1.from_FractionField(a, K0)
def unify_with_symbols(K0, K1, symbols):
if (K0.is_Composite and (set(K0.symbols) & set(symbols))) or (K1.is_Composite and (set(K1.symbols) & set(symbols))):
raise UnificationFailed("can't unify %s with %s, given %s generators" % (K0, K1, tuple(symbols)))
return K0.unify(K1)
def unify(K0, K1, symbols=None):
"""
Construct a minimal domain that contains elements of ``K0`` and ``K1``.
Known domains (from smallest to largest):
- ``GF(p)``
- ``ZZ``
- ``QQ``
- ``RR(prec, tol)``
- ``CC(prec, tol)``
- ``ALG(a, b, c)``
- ``K[x, y, z]``
- ``K(x, y, z)``
- ``EX``
"""
if symbols is not None:
return K0.unify_with_symbols(K1, symbols)
if K0 == K1:
return K0
if K0.is_EX:
return K0
if K1.is_EX:
return K1
if K0.is_Composite or K1.is_Composite:
K0_ground = K0.dom if K0.is_Composite else K0
K1_ground = K1.dom if K1.is_Composite else K1
K0_symbols = K0.symbols if K0.is_Composite else ()
K1_symbols = K1.symbols if K1.is_Composite else ()
domain = K0_ground.unify(K1_ground)
symbols = _unify_gens(K0_symbols, K1_symbols)
order = K0.order if K0.is_Composite else K1.order
if ((K0.is_FractionField and K1.is_PolynomialRing or
K1.is_FractionField and K0.is_PolynomialRing) and
(not K0_ground.is_Field or not K1_ground.is_Field) and domain.is_Field):
domain = domain.get_ring()
if K0.is_Composite and (not K1.is_Composite or K0.is_FractionField or K1.is_PolynomialRing):
cls = K0.__class__
else:
cls = K1.__class__
from sympy.polys.domains.old_polynomialring import GlobalPolynomialRing
if cls == GlobalPolynomialRing:
return cls(domain, symbols)
return cls(domain, symbols, order)
def mkinexact(cls, K0, K1):
prec = max(K0.precision, K1.precision)
tol = max(K0.tolerance, K1.tolerance)
return cls(prec=prec, tol=tol)
if K0.is_ComplexField and K1.is_ComplexField:
return mkinexact(K0.__class__, K0, K1)
if K0.is_ComplexField and K1.is_RealField:
return mkinexact(K0.__class__, K0, K1)
if K0.is_RealField and K1.is_ComplexField:
return mkinexact(K1.__class__, K1, K0)
if K0.is_RealField and K1.is_RealField:
return mkinexact(K0.__class__, K0, K1)
if K0.is_ComplexField or K0.is_RealField:
return K0
if K1.is_ComplexField or K1.is_RealField:
return K1
if K0.is_AlgebraicField and K1.is_AlgebraicField:
return K0.__class__(K0.dom.unify(K1.dom), *_unify_gens(K0.orig_ext, K1.orig_ext))
elif K0.is_AlgebraicField:
return K0
elif K1.is_AlgebraicField:
return K1
if K0.is_RationalField:
return K0
if K1.is_RationalField:
return K1
if K0.is_IntegerRing:
return K0
if K1.is_IntegerRing:
return K1
if K0.is_FiniteField and K1.is_FiniteField:
return K0.__class__(max(K0.mod, K1.mod, key=default_sort_key))
from sympy.polys.domains import EX
return EX
def __eq__(self, other):
"""Returns ``True`` if two domains are equivalent. """
return isinstance(other, Domain) and self.dtype == other.dtype
def __ne__(self, other):
"""Returns ``False`` if two domains are equivalent. """
return not self == other
def map(self, seq):
"""Rersively apply ``self`` to all elements of ``seq``. """
result = []
for elt in seq:
if isinstance(elt, list):
result.append(self.map(elt))
else:
result.append(self(elt))
return result
def get_ring(self):
"""Returns a ring associated with ``self``. """
raise DomainError('there is no ring associated with %s' % self)
def get_field(self):
"""Returns a field associated with ``self``. """
raise DomainError('there is no field associated with %s' % self)
def get_exact(self):
"""Returns an exact domain associated with ``self``. """
return self
def __getitem__(self, symbols):
"""The mathematical way to make a polynomial ring. """
if hasattr(symbols, '__iter__'):
return self.poly_ring(*symbols)
else:
return self.poly_ring(symbols)
def poly_ring(self, *symbols, **kwargs):
"""Returns a polynomial ring, i.e. `K[X]`. """
from sympy.polys.domains.polynomialring import PolynomialRing
return PolynomialRing(self, symbols, kwargs.get("order", lex))
def frac_field(self, *symbols, **kwargs):
"""Returns a fraction field, i.e. `K(X)`. """
from sympy.polys.domains.fractionfield import FractionField
return FractionField(self, symbols, kwargs.get("order", lex))
def old_poly_ring(self, *symbols, **kwargs):
"""Returns a polynomial ring, i.e. `K[X]`. """
from sympy.polys.domains.old_polynomialring import PolynomialRing
return PolynomialRing(self, *symbols, **kwargs)
def old_frac_field(self, *symbols, **kwargs):
"""Returns a fraction field, i.e. `K(X)`. """
from sympy.polys.domains.old_fractionfield import FractionField
return FractionField(self, *symbols, **kwargs)
def algebraic_field(self, *extension):
r"""Returns an algebraic field, i.e. `K(\alpha, \ldots)`. """
raise DomainError("can't create algebraic field over %s" % self)
def inject(self, *symbols):
"""Inject generators into this domain. """
raise NotImplementedError
def is_zero(self, a):
"""Returns True if ``a`` is zero. """
return not a
def is_one(self, a):
"""Returns True if ``a`` is one. """
return a == self.one
def is_positive(self, a):
"""Returns True if ``a`` is positive. """
return a > 0
def is_negative(self, a):
"""Returns True if ``a`` is negative. """
return a < 0
def is_nonpositive(self, a):
"""Returns True if ``a`` is non-positive. """
return a <= 0
def is_nonnegative(self, a):
"""Returns True if ``a`` is non-negative. """
return a >= 0
def abs(self, a):
"""Absolute value of ``a``, implies ``__abs__``. """
return abs(a)
def neg(self, a):
"""Returns ``a`` negated, implies ``__neg__``. """
return -a
def pos(self, a):
"""Returns ``a`` positive, implies ``__pos__``. """
return +a
def add(self, a, b):
"""Sum of ``a`` and ``b``, implies ``__add__``. """
return a + b
def sub(self, a, b):
"""Difference of ``a`` and ``b``, implies ``__sub__``. """
return a - b
def mul(self, a, b):
"""Product of ``a`` and ``b``, implies ``__mul__``. """
return a * b
def pow(self, a, b):
"""Raise ``a`` to power ``b``, implies ``__pow__``. """
return a ** b
def exquo(self, a, b):
"""Exact quotient of ``a`` and ``b``, implies something. """
raise NotImplementedError
def quo(self, a, b):
"""Quotient of ``a`` and ``b``, implies something. """
raise NotImplementedError
def rem(self, a, b):
"""Remainder of ``a`` and ``b``, implies ``__mod__``. """
raise NotImplementedError
def div(self, a, b):
"""Division of ``a`` and ``b``, implies something. """
raise NotImplementedError
def invert(self, a, b):
"""Returns inversion of ``a mod b``, implies something. """
raise NotImplementedError
def revert(self, a):
"""Returns ``a**(-1)`` if possible. """
raise NotImplementedError
def numer(self, a):
"""Returns numerator of ``a``. """
raise NotImplementedError
def denom(self, a):
"""Returns denominator of ``a``. """
raise NotImplementedError
def half_gcdex(self, a, b):
"""Half extended GCD of ``a`` and ``b``. """
s, t, h = self.gcdex(a, b)
return s, h
def gcdex(self, a, b):
"""Extended GCD of ``a`` and ``b``. """
raise NotImplementedError
def cofactors(self, a, b):
"""Returns GCD and cofactors of ``a`` and ``b``. """
gcd = self.gcd(a, b)
cfa = self.quo(a, gcd)
cfb = self.quo(b, gcd)
return gcd, cfa, cfb
def gcd(self, a, b):
"""Returns GCD of ``a`` and ``b``. """
raise NotImplementedError
def lcm(self, a, b):
"""Returns LCM of ``a`` and ``b``. """
raise NotImplementedError
def log(self, a, b):
"""Returns b-base logarithm of ``a``. """
raise NotImplementedError
def sqrt(self, a):
"""Returns square root of ``a``. """
raise NotImplementedError
def evalf(self, a, prec=None, **options):
"""Returns numerical approximation of ``a``. """
return self.to_sympy(a).evalf(prec, **options)
n = evalf
def real(self, a):
return a
def imag(self, a):
return self.zero
def almosteq(self, a, b, tolerance=None):
"""Check if ``a`` and ``b`` are almost equal. """
return a == b
def characteristic(self):
"""Return the characteristic of this domain. """
raise NotImplementedError('characteristic()')
|
89a29706188ca9581eab61f4d647abffbfc8681853d1c0efe4828c4e7d0ca3cd
|
"""Real and complex elements. """
from __future__ import print_function, division
from sympy.core.compatibility import string_types
from sympy.polys.domains.domainelement import DomainElement
from sympy.utilities import public
from mpmath.ctx_mp_python import PythonMPContext, _mpf, _mpc, _constant
from mpmath.libmp import (MPZ_ONE, fzero, fone, finf, fninf, fnan,
round_nearest, mpf_mul, repr_dps, int_types,
from_int, from_float, from_str, to_rational)
from mpmath.rational import mpq
@public
class RealElement(_mpf, DomainElement):
"""An element of a real domain. """
__slots__ = ['__mpf__']
def _set_mpf(self, val):
self.__mpf__ = val
_mpf_ = property(lambda self: self.__mpf__, _set_mpf)
def parent(self):
return self.context._parent
@public
class ComplexElement(_mpc, DomainElement):
"""An element of a complex domain. """
__slots__ = ['__mpc__']
def _set_mpc(self, val):
self.__mpc__ = val
_mpc_ = property(lambda self: self.__mpc__, _set_mpc)
def parent(self):
return self.context._parent
new = object.__new__
@public
class MPContext(PythonMPContext):
def __init__(ctx, prec=53, dps=None, tol=None):
ctx._prec_rounding = [prec, round_nearest]
if dps is None:
ctx._set_prec(prec)
else:
ctx._set_dps(dps)
ctx.mpf = RealElement
ctx.mpc = ComplexElement
ctx.mpf._ctxdata = [ctx.mpf, new, ctx._prec_rounding]
ctx.mpc._ctxdata = [ctx.mpc, new, ctx._prec_rounding]
ctx.mpf.context = ctx
ctx.mpc.context = ctx
ctx.constant = _constant
ctx.constant._ctxdata = [ctx.mpf, new, ctx._prec_rounding]
ctx.constant.context = ctx
ctx.types = [ctx.mpf, ctx.mpc, ctx.constant]
ctx.trap_complex = True
ctx.pretty = True
if tol is None:
ctx.tol = ctx._make_tol()
elif tol is False:
ctx.tol = fzero
else:
ctx.tol = ctx._convert_tol(tol)
ctx.tolerance = ctx.make_mpf(ctx.tol)
if not ctx.tolerance:
ctx.max_denom = 1000000
else:
ctx.max_denom = int(1/ctx.tolerance)
ctx.zero = ctx.make_mpf(fzero)
ctx.one = ctx.make_mpf(fone)
ctx.j = ctx.make_mpc((fzero, fone))
ctx.inf = ctx.make_mpf(finf)
ctx.ninf = ctx.make_mpf(fninf)
ctx.nan = ctx.make_mpf(fnan)
def _make_tol(ctx):
hundred = (0, 25, 2, 5)
eps = (0, MPZ_ONE, 1-ctx.prec, 1)
return mpf_mul(hundred, eps)
def make_tol(ctx):
return ctx.make_mpf(ctx._make_tol())
def _convert_tol(ctx, tol):
if isinstance(tol, int_types):
return from_int(tol)
if isinstance(tol, float):
return from_float(tol)
if hasattr(tol, "_mpf_"):
return tol._mpf_
prec, rounding = ctx._prec_rounding
if isinstance(tol, string_types):
return from_str(tol, prec, rounding)
raise ValueError("expected a real number, got %s" % tol)
def _convert_fallback(ctx, x, strings):
raise TypeError("cannot create mpf from " + repr(x))
@property
def _repr_digits(ctx):
return repr_dps(ctx._prec)
@property
def _str_digits(ctx):
return ctx._dps
def to_rational(ctx, s, limit=True):
p, q = to_rational(s._mpf_)
if not limit or q <= ctx.max_denom:
return p, q
p0, q0, p1, q1 = 0, 1, 1, 0
n, d = p, q
while True:
a = n//d
q2 = q0 + a*q1
if q2 > ctx.max_denom:
break
p0, q0, p1, q1 = p1, q1, p0 + a*p1, q2
n, d = d, n - a*d
k = (ctx.max_denom - q0)//q1
number = mpq(p, q)
bound1 = mpq(p0 + k*p1, q0 + k*q1)
bound2 = mpq(p1, q1)
if not bound2 or not bound1:
return p, q
elif abs(bound2 - number) <= abs(bound1 - number):
return bound2._mpq_
else:
return bound1._mpq_
def almosteq(ctx, s, t, rel_eps=None, abs_eps=None):
t = ctx.convert(t)
if abs_eps is None and rel_eps is None:
rel_eps = abs_eps = ctx.tolerance or ctx.make_tol()
if abs_eps is None:
abs_eps = ctx.convert(rel_eps)
elif rel_eps is None:
rel_eps = ctx.convert(abs_eps)
diff = abs(s-t)
if diff <= abs_eps:
return True
abss = abs(s)
abst = abs(t)
if abss < abst:
err = diff/abst
else:
err = diff/abss
return err <= rel_eps
|
7359f99fe529e21528839a45eeec7236255987f98dede6fadcda3ee422ccb225
|
"""Tests for low-level linear systems solver. """
from sympy.matrices import Matrix
from sympy.polys.domains import ZZ, QQ
from sympy.polys.fields import field
from sympy.polys.rings import ring
from sympy.polys.solvers import solve_lin_sys, eqs_to_matrix
def test_solve_lin_sys_2x2_one():
domain, x1,x2 = ring("x1,x2", QQ)
eqs = [x1 + x2 - 5,
2*x1 - x2]
sol = {x1: QQ(5, 3), x2: QQ(10, 3)}
_sol = solve_lin_sys(eqs, domain)
assert _sol == sol and all(isinstance(s, domain.dtype) for s in _sol)
def test_solve_lin_sys_2x4_none():
domain, x1,x2 = ring("x1,x2", QQ)
eqs = [x1 - 1,
x1 - x2,
x1 - 2*x2,
x2 - 1]
assert solve_lin_sys(eqs, domain) is None
def test_solve_lin_sys_3x4_one():
domain, x1,x2,x3 = ring("x1,x2,x3", QQ)
eqs = [x1 + 2*x2 + 3*x3,
2*x1 - x2 + x3,
3*x1 + x2 + x3,
5*x2 + 2*x3]
sol = {x1: 0, x2: 0, x3: 0}
assert solve_lin_sys(eqs, domain) == sol
def test_solve_lin_sys_3x3_inf():
domain, x1,x2,x3 = ring("x1,x2,x3", QQ)
eqs = [x1 - x2 + 2*x3 - 1,
2*x1 + x2 + x3 - 8,
x1 + x2 - 5]
sol = {x1: -x3 + 3, x2: x3 + 2}
assert solve_lin_sys(eqs, domain) == sol
def test_solve_lin_sys_3x4_none():
domain, x1,x2,x3,x4 = ring("x1,x2,x3,x4", QQ)
eqs = [2*x1 + x2 + 7*x3 - 7*x4 - 2,
-3*x1 + 4*x2 - 5*x3 - 6*x4 - 3,
x1 + x2 + 4*x3 - 5*x4 - 2]
assert solve_lin_sys(eqs, domain) is None
def test_solve_lin_sys_4x7_inf():
domain, x1,x2,x3,x4,x5,x6,x7 = ring("x1,x2,x3,x4,x5,x6,x7", QQ)
eqs = [x1 + 4*x2 - x4 + 7*x6 - 9*x7 - 3,
2*x1 + 8*x2 - x3 + 3*x4 + 9*x5 - 13*x6 + 7*x7 - 9,
2*x3 - 3*x4 - 4*x5 + 12*x6 - 8*x7 - 1,
-x1 - 4*x2 + 2*x3 + 4*x4 + 8*x5 - 31*x6 + 37*x7 - 4]
sol = {x1: 4 - 4*x2 - 2*x5 - x6 + 3*x7,
x3: 2 - x5 + 3*x6 - 5*x7,
x4: 1 - 2*x5 + 6*x6 - 6*x7}
assert solve_lin_sys(eqs, domain) == sol
def test_solve_lin_sys_5x5_inf():
domain, x1,x2,x3,x4,x5 = ring("x1,x2,x3,x4,x5", QQ)
eqs = [x1 - x2 - 2*x3 + x4 + 11*x5 - 13,
x1 - x2 + x3 + x4 + 5*x5 - 16,
2*x1 - 2*x2 + x4 + 10*x5 - 21,
2*x1 - 2*x2 - x3 + 3*x4 + 20*x5 - 38,
2*x1 - 2*x2 + x3 + x4 + 8*x5 - 22]
sol = {x1: 6 + x2 - 3*x5,
x3: 1 + 2*x5,
x4: 9 - 4*x5}
assert solve_lin_sys(eqs, domain) == sol
def test_solve_lin_sys_6x6_1():
ground, d,r,e,g,i,j,l,o,m,p,q = field("d,r,e,g,i,j,l,o,m,p,q", ZZ)
domain, c,f,h,k,n,b = ring("c,f,h,k,n,b", ground)
eqs = [b + q/d - c/d, c*(1/d + 1/e + 1/g) - f/g - q/d, f*(1/g + 1/i + 1/j) - c/g - h/i, h*(1/i + 1/l + 1/m) - f/i - k/m, k*(1/m + 1/o + 1/p) - h/m - n/p, n/p - k/p]
sol = {
b: (e*i*l*q + e*i*m*q + e*i*o*q + e*j*l*q + e*j*m*q + e*j*o*q + e*l*m*q + e*l*o*q + g*i*l*q + g*i*m*q + g*i*o*q + g*j*l*q + g*j*m*q + g*j*o*q + g*l*m*q + g*l*o*q + i*j*l*q + i*j*m*q + i*j*o*q + j*l*m*q + j*l*o*q)/(-d*e*i*l - d*e*i*m - d*e*i*o - d*e*j*l - d*e*j*m - d*e*j*o - d*e*l*m - d*e*l*o - d*g*i*l - d*g*i*m - d*g*i*o - d*g*j*l - d*g*j*m - d*g*j*o - d*g*l*m - d*g*l*o - d*i*j*l - d*i*j*m - d*i*j*o - d*j*l*m - d*j*l*o - e*g*i*l - e*g*i*m - e*g*i*o - e*g*j*l - e*g*j*m - e*g*j*o - e*g*l*m - e*g*l*o - e*i*j*l - e*i*j*m - e*i*j*o - e*j*l*m - e*j*l*o),
c: (-e*g*i*l*q - e*g*i*m*q - e*g*i*o*q - e*g*j*l*q - e*g*j*m*q - e*g*j*o*q - e*g*l*m*q - e*g*l*o*q - e*i*j*l*q - e*i*j*m*q - e*i*j*o*q - e*j*l*m*q - e*j*l*o*q)/(-d*e*i*l - d*e*i*m - d*e*i*o - d*e*j*l - d*e*j*m - d*e*j*o - d*e*l*m - d*e*l*o - d*g*i*l - d*g*i*m - d*g*i*o - d*g*j*l - d*g*j*m - d*g*j*o - d*g*l*m - d*g*l*o - d*i*j*l - d*i*j*m - d*i*j*o - d*j*l*m - d*j*l*o - e*g*i*l - e*g*i*m - e*g*i*o - e*g*j*l - e*g*j*m - e*g*j*o - e*g*l*m - e*g*l*o - e*i*j*l - e*i*j*m - e*i*j*o - e*j*l*m - e*j*l*o),
f: (-e*i*j*l*q - e*i*j*m*q - e*i*j*o*q - e*j*l*m*q - e*j*l*o*q)/(-d*e*i*l - d*e*i*m - d*e*i*o - d*e*j*l - d*e*j*m - d*e*j*o - d*e*l*m - d*e*l*o - d*g*i*l - d*g*i*m - d*g*i*o - d*g*j*l - d*g*j*m - d*g*j*o - d*g*l*m - d*g*l*o - d*i*j*l - d*i*j*m - d*i*j*o - d*j*l*m - d*j*l*o - e*g*i*l - e*g*i*m - e*g*i*o - e*g*j*l - e*g*j*m - e*g*j*o - e*g*l*m - e*g*l*o - e*i*j*l - e*i*j*m - e*i*j*o - e*j*l*m - e*j*l*o),
h: (-e*j*l*m*q - e*j*l*o*q)/(-d*e*i*l - d*e*i*m - d*e*i*o - d*e*j*l - d*e*j*m - d*e*j*o - d*e*l*m - d*e*l*o - d*g*i*l - d*g*i*m - d*g*i*o - d*g*j*l - d*g*j*m - d*g*j*o - d*g*l*m - d*g*l*o - d*i*j*l - d*i*j*m - d*i*j*o - d*j*l*m - d*j*l*o - e*g*i*l - e*g*i*m - e*g*i*o - e*g*j*l - e*g*j*m - e*g*j*o - e*g*l*m - e*g*l*o - e*i*j*l - e*i*j*m - e*i*j*o - e*j*l*m - e*j*l*o),
k: e*j*l*o*q/(d*e*i*l + d*e*i*m + d*e*i*o + d*e*j*l + d*e*j*m + d*e*j*o + d*e*l*m + d*e*l*o + d*g*i*l + d*g*i*m + d*g*i*o + d*g*j*l + d*g*j*m + d*g*j*o + d*g*l*m + d*g*l*o + d*i*j*l + d*i*j*m + d*i*j*o + d*j*l*m + d*j*l*o + e*g*i*l + e*g*i*m + e*g*i*o + e*g*j*l + e*g*j*m + e*g*j*o + e*g*l*m + e*g*l*o + e*i*j*l + e*i*j*m + e*i*j*o + e*j*l*m + e*j*l*o),
n: e*j*l*o*q/(d*e*i*l + d*e*i*m + d*e*i*o + d*e*j*l + d*e*j*m + d*e*j*o + d*e*l*m + d*e*l*o + d*g*i*l + d*g*i*m + d*g*i*o + d*g*j*l + d*g*j*m + d*g*j*o + d*g*l*m + d*g*l*o + d*i*j*l + d*i*j*m + d*i*j*o + d*j*l*m + d*j*l*o + e*g*i*l + e*g*i*m + e*g*i*o + e*g*j*l + e*g*j*m + e*g*j*o + e*g*l*m + e*g*l*o + e*i*j*l + e*i*j*m + e*i*j*o + e*j*l*m + e*j*l*o),
}
assert solve_lin_sys(eqs, domain) == sol
def test_solve_lin_sys_6x6_2():
ground, d,r,e,g,i,j,l,o,m,p,q = field("d,r,e,g,i,j,l,o,m,p,q", ZZ)
domain, c,f,h,k,n,b = ring("c,f,h,k,n,b", ground)
eqs = [b + r/d - c/d, c*(1/d + 1/e + 1/g) - f/g - r/d, f*(1/g + 1/i + 1/j) - c/g - h/i, h*(1/i + 1/l + 1/m) - f/i - k/m, k*(1/m + 1/o + 1/p) - h/m - n/p, n*(1/p + 1/q) - k/p]
sol = {
b: -((l*q*e*o + l*q*g*o + i*m*q*e + i*l*q*e + i*l*p*e + i*j*o*q + j*e*o*q + g*j*o*q + i*e*o*q + g*i*o*q + e*l*o*p + e*l*m*p + e*l*m*o + e*i*o*p + e*i*m*p + e*i*m*o + e*i*l*o + j*e*o*p + j*e*m*q + j*e*m*p + j*e*m*o + j*l*m*q + j*l*m*p + j*l*m*o + i*j*m*p + i*j*m*o + i*j*l*q + i*j*l*o + i*j*m*q + j*l*o*p + j*e*l*o + g*j*o*p + g*j*m*q + g*j*m*p + i*j*l*p + i*j*o*p + j*e*l*q + j*e*l*p + j*l*o*q + g*j*m*o + g*j*l*q + g*j*l*p + g*j*l*o + g*l*o*p + g*l*m*p + g*l*m*o + g*i*m*o + g*i*o*p + g*i*m*q + g*i*m*p + g*i*l*q + g*i*l*p + g*i*l*o + l*m*q*e + l*m*q*g)*r)/(l*q*d*e*o + l*q*d*g*o + l*q*e*g*o + i*j*d*o*q + i*j*e*o*q + j*d*e*o*q + g*j*d*o*q + g*j*e*o*q + g*i*e*o*q + i*d*e*o*q + g*i*d*o*q + g*i*d*o*p + g*i*d*m*q + g*i*d*m*p + g*i*d*m*o + g*i*d*l*q + g*i*d*l*p + g*i*d*l*o + g*e*l*m*p + g*e*l*o*p + g*j*e*l*q + g*e*l*m*o + g*j*e*m*p + g*j*e*m*o + d*e*l*m*p + d*e*l*m*o + i*d*e*m*p + g*j*e*l*p + g*j*e*l*o + d*e*l*o*p + i*j*d*l*o + i*j*e*o*p + i*j*e*m*q + i*j*d*m*q + i*j*d*m*p + i*j*d*m*o + i*j*d*l*q + i*j*d*l*p + i*j*e*m*p + i*j*e*m*o + i*j*e*l*q + i*j*e*l*p + i*j*e*l*o + i*d*e*m*q + i*d*e*m*o + i*d*e*l*q + i*d*e*l*p + j*d*l*o*p + j*d*e*l*o + g*j*d*o*p + g*j*d*m*q + g*j*d*m*p + g*j*d*m*o + g*j*d*l*q + g*j*d*l*p + g*j*d*l*o + g*j*e*o*p + g*j*e*m*q + g*d*l*o*p + g*d*l*m*p + g*d*l*m*o + j*d*e*m*p + i*d*e*o*p + j*e*o*q*l + j*e*o*p*l + j*e*m*q*l + j*d*e*o*p + j*d*e*m*q + i*j*d*o*p + g*i*e*o*p + j*d*e*m*o + j*d*e*l*q + j*d*e*l*p + j*e*m*p*l + j*e*m*o*l + g*i*e*m*q + g*i*e*m*p + g*i*e*m*o + g*i*e*l*q + g*i*e*l*p + g*i*e*l*o + j*d*l*o*q + j*d*l*m*q + j*d*l*m*p + j*d*l*m*o + i*d*e*l*o + l*m*q*d*e + l*m*q*d*g + l*m*q*e*g),
c: (r*e*(l*q*g*o + i*j*o*q + g*j*o*q + g*i*o*q + j*l*m*q + j*l*m*p + j*l*m*o + i*j*m*p + i*j*m*o + i*j*l*q + i*j*l*o + i*j*m*q + j*l*o*p + g*j*o*p + g*j*m*q + g*j*m*p + i*j*l*p + i*j*o*p + j*l*o*q + g*j*m*o + g*j*l*q + g*j*l*p + g*j*l*o + g*l*o*p + g*l*m*p + g*l*m*o + g*i*m*o + g*i*o*p + g*i*m*q + g*i*m*p + g*i*l*q + g*i*l*p + g*i*l*o + l*m*q*g))/(l*q*d*e*o + l*q*d*g*o + l*q*e*g*o + i*j*d*o*q + i*j*e*o*q + j*d*e*o*q + g*j*d*o*q + g*j*e*o*q + g*i*e*o*q + i*d*e*o*q + g*i*d*o*q + g*i*d*o*p + g*i*d*m*q + g*i*d*m*p + g*i*d*m*o + g*i*d*l*q + g*i*d*l*p + g*i*d*l*o + g*e*l*m*p + g*e*l*o*p + g*j*e*l*q + g*e*l*m*o + g*j*e*m*p + g*j*e*m*o + d*e*l*m*p + d*e*l*m*o + i*d*e*m*p + g*j*e*l*p + g*j*e*l*o + d*e*l*o*p + i*j*d*l*o + i*j*e*o*p + i*j*e*m*q + i*j*d*m*q + i*j*d*m*p + i*j*d*m*o + i*j*d*l*q + i*j*d*l*p + i*j*e*m*p + i*j*e*m*o + i*j*e*l*q + i*j*e*l*p + i*j*e*l*o + i*d*e*m*q + i*d*e*m*o + i*d*e*l*q + i*d*e*l*p + j*d*l*o*p + j*d*e*l*o + g*j*d*o*p + g*j*d*m*q + g*j*d*m*p + g*j*d*m*o + g*j*d*l*q + g*j*d*l*p + g*j*d*l*o + g*j*e*o*p + g*j*e*m*q + g*d*l*o*p + g*d*l*m*p + g*d*l*m*o + j*d*e*m*p + i*d*e*o*p + j*e*o*q*l + j*e*o*p*l + j*e*m*q*l + j*d*e*o*p + j*d*e*m*q + i*j*d*o*p + g*i*e*o*p + j*d*e*m*o + j*d*e*l*q + j*d*e*l*p + j*e*m*p*l + j*e*m*o*l + g*i*e*m*q + g*i*e*m*p + g*i*e*m*o + g*i*e*l*q + g*i*e*l*p + g*i*e*l*o + j*d*l*o*q + j*d*l*m*q + j*d*l*m*p + j*d*l*m*o + i*d*e*l*o + l*m*q*d*e + l*m*q*d*g + l*m*q*e*g),
f: (r*e*j*(l*q*o + l*o*p + l*m*q + l*m*p + l*m*o + i*o*q + i*o*p + i*m*q + i*m*p + i*m*o + i*l*q + i*l*p + i*l*o))/(l*q*d*e*o + l*q*d*g*o + l*q*e*g*o + i*j*d*o*q + i*j*e*o*q + j*d*e*o*q + g*j*d*o*q + g*j*e*o*q + g*i*e*o*q + i*d*e*o*q + g*i*d*o*q + g*i*d*o*p + g*i*d*m*q + g*i*d*m*p + g*i*d*m*o + g*i*d*l*q + g*i*d*l*p + g*i*d*l*o + g*e*l*m*p + g*e*l*o*p + g*j*e*l*q + g*e*l*m*o + g*j*e*m*p + g*j*e*m*o + d*e*l*m*p + d*e*l*m*o + i*d*e*m*p + g*j*e*l*p + g*j*e*l*o + d*e*l*o*p + i*j*d*l*o + i*j*e*o*p + i*j*e*m*q + i*j*d*m*q + i*j*d*m*p + i*j*d*m*o + i*j*d*l*q + i*j*d*l*p + i*j*e*m*p + i*j*e*m*o + i*j*e*l*q + i*j*e*l*p + i*j*e*l*o + i*d*e*m*q + i*d*e*m*o + i*d*e*l*q + i*d*e*l*p + j*d*l*o*p + j*d*e*l*o + g*j*d*o*p + g*j*d*m*q + g*j*d*m*p + g*j*d*m*o + g*j*d*l*q + g*j*d*l*p + g*j*d*l*o + g*j*e*o*p + g*j*e*m*q + g*d*l*o*p + g*d*l*m*p + g*d*l*m*o + j*d*e*m*p + i*d*e*o*p + j*e*o*q*l + j*e*o*p*l + j*e*m*q*l + j*d*e*o*p + j*d*e*m*q + i*j*d*o*p + g*i*e*o*p + j*d*e*m*o + j*d*e*l*q + j*d*e*l*p + j*e*m*p*l + j*e*m*o*l + g*i*e*m*q + g*i*e*m*p + g*i*e*m*o + g*i*e*l*q + g*i*e*l*p + g*i*e*l*o + j*d*l*o*q + j*d*l*m*q + j*d*l*m*p + j*d*l*m*o + i*d*e*l*o + l*m*q*d*e + l*m*q*d*g + l*m*q*e*g),
h: (j*e*r*l*(o*q + o*p + m*q + m*p + m*o))/(l*q*d*e*o + l*q*d*g*o + l*q*e*g*o + i*j*d*o*q + i*j*e*o*q + j*d*e*o*q + g*j*d*o*q + g*j*e*o*q + g*i*e*o*q + i*d*e*o*q + g*i*d*o*q + g*i*d*o*p + g*i*d*m*q + g*i*d*m*p + g*i*d*m*o + g*i*d*l*q + g*i*d*l*p + g*i*d*l*o + g*e*l*m*p + g*e*l*o*p + g*j*e*l*q + g*e*l*m*o + g*j*e*m*p + g*j*e*m*o + d*e*l*m*p + d*e*l*m*o + i*d*e*m*p + g*j*e*l*p + g*j*e*l*o + d*e*l*o*p + i*j*d*l*o + i*j*e*o*p + i*j*e*m*q + i*j*d*m*q + i*j*d*m*p + i*j*d*m*o + i*j*d*l*q + i*j*d*l*p + i*j*e*m*p + i*j*e*m*o + i*j*e*l*q + i*j*e*l*p + i*j*e*l*o + i*d*e*m*q + i*d*e*m*o + i*d*e*l*q + i*d*e*l*p + j*d*l*o*p + j*d*e*l*o + g*j*d*o*p + g*j*d*m*q + g*j*d*m*p + g*j*d*m*o + g*j*d*l*q + g*j*d*l*p + g*j*d*l*o + g*j*e*o*p + g*j*e*m*q + g*d*l*o*p + g*d*l*m*p + g*d*l*m*o + j*d*e*m*p + i*d*e*o*p + j*e*o*q*l + j*e*o*p*l + j*e*m*q*l + j*d*e*o*p + j*d*e*m*q + i*j*d*o*p + g*i*e*o*p + j*d*e*m*o + j*d*e*l*q + j*d*e*l*p + j*e*m*p*l + j*e*m*o*l + g*i*e*m*q + g*i*e*m*p + g*i*e*m*o + g*i*e*l*q + g*i*e*l*p + g*i*e*l*o + j*d*l*o*q + j*d*l*m*q + j*d*l*m*p + j*d*l*m*o + i*d*e*l*o + l*m*q*d*e + l*m*q*d*g + l*m*q*e*g),
k: (j*e*r*o*l*(q + p))/(l*q*d*e*o + l*q*d*g*o + l*q*e*g*o + i*j*d*o*q + i*j*e*o*q + j*d*e*o*q + g*j*d*o*q + g*j*e*o*q + g*i*e*o*q + i*d*e*o*q + g*i*d*o*q + g*i*d*o*p + g*i*d*m*q + g*i*d*m*p + g*i*d*m*o + g*i*d*l*q + g*i*d*l*p + g*i*d*l*o + g*e*l*m*p + g*e*l*o*p + g*j*e*l*q + g*e*l*m*o + g*j*e*m*p + g*j*e*m*o + d*e*l*m*p + d*e*l*m*o + i*d*e*m*p + g*j*e*l*p + g*j*e*l*o + d*e*l*o*p + i*j*d*l*o + i*j*e*o*p + i*j*e*m*q + i*j*d*m*q + i*j*d*m*p + i*j*d*m*o + i*j*d*l*q + i*j*d*l*p + i*j*e*m*p + i*j*e*m*o + i*j*e*l*q + i*j*e*l*p + i*j*e*l*o + i*d*e*m*q + i*d*e*m*o + i*d*e*l*q + i*d*e*l*p + j*d*l*o*p + j*d*e*l*o + g*j*d*o*p + g*j*d*m*q + g*j*d*m*p + g*j*d*m*o + g*j*d*l*q + g*j*d*l*p + g*j*d*l*o + g*j*e*o*p + g*j*e*m*q + g*d*l*o*p + g*d*l*m*p + g*d*l*m*o + j*d*e*m*p + i*d*e*o*p + j*e*o*q*l + j*e*o*p*l + j*e*m*q*l + j*d*e*o*p + j*d*e*m*q + i*j*d*o*p + g*i*e*o*p + j*d*e*m*o + j*d*e*l*q + j*d*e*l*p + j*e*m*p*l + j*e*m*o*l + g*i*e*m*q + g*i*e*m*p + g*i*e*m*o + g*i*e*l*q + g*i*e*l*p + g*i*e*l*o + j*d*l*o*q + j*d*l*m*q + j*d*l*m*p + j*d*l*m*o + i*d*e*l*o + l*m*q*d*e + l*m*q*d*g + l*m*q*e*g),
n: (j*e*r*o*q*l)/(l*q*d*e*o + l*q*d*g*o + l*q*e*g*o + i*j*d*o*q + i*j*e*o*q + j*d*e*o*q + g*j*d*o*q + g*j*e*o*q + g*i*e*o*q + i*d*e*o*q + g*i*d*o*q + g*i*d*o*p + g*i*d*m*q + g*i*d*m*p + g*i*d*m*o + g*i*d*l*q + g*i*d*l*p + g*i*d*l*o + g*e*l*m*p + g*e*l*o*p + g*j*e*l*q + g*e*l*m*o + g*j*e*m*p + g*j*e*m*o + d*e*l*m*p + d*e*l*m*o + i*d*e*m*p + g*j*e*l*p + g*j*e*l*o + d*e*l*o*p + i*j*d*l*o + i*j*e*o*p + i*j*e*m*q + i*j*d*m*q + i*j*d*m*p + i*j*d*m*o + i*j*d*l*q + i*j*d*l*p + i*j*e*m*p + i*j*e*m*o + i*j*e*l*q + i*j*e*l*p + i*j*e*l*o + i*d*e*m*q + i*d*e*m*o + i*d*e*l*q + i*d*e*l*p + j*d*l*o*p + j*d*e*l*o + g*j*d*o*p + g*j*d*m*q + g*j*d*m*p + g*j*d*m*o + g*j*d*l*q + g*j*d*l*p + g*j*d*l*o + g*j*e*o*p + g*j*e*m*q + g*d*l*o*p + g*d*l*m*p + g*d*l*m*o + j*d*e*m*p + i*d*e*o*p + j*e*o*q*l + j*e*o*p*l + j*e*m*q*l + j*d*e*o*p + j*d*e*m*q + i*j*d*o*p + g*i*e*o*p + j*d*e*m*o + j*d*e*l*q + j*d*e*l*p + j*e*m*p*l + j*e*m*o*l + g*i*e*m*q + g*i*e*m*p + g*i*e*m*o + g*i*e*l*q + g*i*e*l*p + g*i*e*l*o + j*d*l*o*q + j*d*l*m*q + j*d*l*m*p + j*d*l*m*o + i*d*e*l*o + l*m*q*d*e + l*m*q*d*g + l*m*q*e*g),
}
assert solve_lin_sys(eqs, domain) == sol
def test_eqs_to_matrix():
domain, x1,x2 = ring("x1,x2", QQ)
eqs = [x1 + x2 - 5,
2*x1 - x2]
assert Matrix([[1, 1, 5], [2, -1, 0]]).__eq__(eqs_to_matrix(eqs, domain))
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f82e7b0f24110559fc3df5966dfa76e18bad465f82f3d47c39c453dc474b4d3b
|
"""Tests for Groebner bases. """
from sympy.polys.groebnertools import (
groebner, sig, sig_key,
lbp, lbp_key, critical_pair,
cp_key, is_rewritable_or_comparable,
Sign, Polyn, Num, s_poly, f5_reduce,
groebner_lcm, groebner_gcd, is_groebner
)
from sympy.polys.fglmtools import _representing_matrices
from sympy.polys.orderings import lex, grlex
from sympy.polys.rings import ring, xring
from sympy.polys.domains import ZZ, QQ
from sympy.utilities.pytest import slow
from sympy.polys import polyconfig as config
from sympy.core.compatibility import range
def _do_test_groebner():
R, x,y = ring("x,y", QQ, lex)
f = x**2 + 2*x*y**2
g = x*y + 2*y**3 - 1
assert groebner([f, g], R) == [x, y**3 - QQ(1,2)]
R, y,x = ring("y,x", QQ, lex)
f = 2*x**2*y + y**2
g = 2*x**3 + x*y - 1
assert groebner([f, g], R) == [y, x**3 - QQ(1,2)]
R, x,y,z = ring("x,y,z", QQ, lex)
f = x - z**2
g = y - z**3
assert groebner([f, g], R) == [f, g]
R, x,y = ring("x,y", QQ, grlex)
f = x**3 - 2*x*y
g = x**2*y + x - 2*y**2
assert groebner([f, g], R) == [x**2, x*y, -QQ(1,2)*x + y**2]
R, x,y,z = ring("x,y,z", QQ, lex)
f = -x**2 + y
g = -x**3 + z
assert groebner([f, g], R) == [x**2 - y, x*y - z, x*z - y**2, y**3 - z**2]
R, x,y,z = ring("x,y,z", QQ, grlex)
f = -x**2 + y
g = -x**3 + z
assert groebner([f, g], R) == [y**3 - z**2, x**2 - y, x*y - z, x*z - y**2]
R, x,y,z = ring("x,y,z", QQ, lex)
f = -x**2 + z
g = -x**3 + y
assert groebner([f, g], R) == [x**2 - z, x*y - z**2, x*z - y, y**2 - z**3]
R, x,y,z = ring("x,y,z", QQ, grlex)
f = -x**2 + z
g = -x**3 + y
assert groebner([f, g], R) == [-y**2 + z**3, x**2 - z, x*y - z**2, x*z - y]
R, x,y,z = ring("x,y,z", QQ, lex)
f = x - y**2
g = -y**3 + z
assert groebner([f, g], R) == [x - y**2, y**3 - z]
R, x,y,z = ring("x,y,z", QQ, grlex)
f = x - y**2
g = -y**3 + z
assert groebner([f, g], R) == [x**2 - y*z, x*y - z, -x + y**2]
R, x,y,z = ring("x,y,z", QQ, lex)
f = x - z**2
g = y - z**3
assert groebner([f, g], R) == [x - z**2, y - z**3]
R, x,y,z = ring("x,y,z", QQ, grlex)
f = x - z**2
g = y - z**3
assert groebner([f, g], R) == [x**2 - y*z, x*z - y, -x + z**2]
R, x,y,z = ring("x,y,z", QQ, lex)
f = -y**2 + z
g = x - y**3
assert groebner([f, g], R) == [x - y*z, y**2 - z]
R, x,y,z = ring("x,y,z", QQ, grlex)
f = -y**2 + z
g = x - y**3
assert groebner([f, g], R) == [-x**2 + z**3, x*y - z**2, y**2 - z, -x + y*z]
R, x,y,z = ring("x,y,z", QQ, lex)
f = y - z**2
g = x - z**3
assert groebner([f, g], R) == [x - z**3, y - z**2]
R, x,y,z = ring("x,y,z", QQ, grlex)
f = y - z**2
g = x - z**3
assert groebner([f, g], R) == [-x**2 + y**3, x*z - y**2, -x + y*z, -y + z**2]
R, x,y,z = ring("x,y,z", QQ, lex)
f = 4*x**2*y**2 + 4*x*y + 1
g = x**2 + y**2 - 1
assert groebner([f, g], R) == [
x - 4*y**7 + 8*y**5 - 7*y**3 + 3*y,
y**8 - 2*y**6 + QQ(3,2)*y**4 - QQ(1,2)*y**2 + QQ(1,16),
]
def test_groebner_buchberger():
with config.using(groebner='buchberger'):
_do_test_groebner()
def test_groebner_f5b():
with config.using(groebner='f5b'):
_do_test_groebner()
def _do_test_benchmark_minpoly():
R, x,y,z = ring("x,y,z", QQ, lex)
F = [x**3 + x + 1, y**2 + y + 1, (x + y) * z - (x**2 + y)]
G = [x + QQ(155,2067)*z**5 - QQ(355,689)*z**4 + QQ(6062,2067)*z**3 - QQ(3687,689)*z**2 + QQ(6878,2067)*z - QQ(25,53),
y + QQ(4,53)*z**5 - QQ(91,159)*z**4 + QQ(523,159)*z**3 - QQ(387,53)*z**2 + QQ(1043,159)*z - QQ(308,159),
z**6 - 7*z**5 + 41*z**4 - 82*z**3 + 89*z**2 - 46*z + 13]
assert groebner(F, R) == G
def test_benchmark_minpoly_buchberger():
with config.using(groebner='buchberger'):
_do_test_benchmark_minpoly()
def test_benchmark_minpoly_f5b():
with config.using(groebner='f5b'):
_do_test_benchmark_minpoly()
def test_benchmark_coloring():
V = range(1, 12 + 1)
E = [(1, 2), (2, 3), (1, 4), (1, 6), (1, 12), (2, 5), (2, 7), (3, 8), (3, 10),
(4, 11), (4, 9), (5, 6), (6, 7), (7, 8), (8, 9), (9, 10), (10, 11),
(11, 12), (5, 12), (5, 9), (6, 10), (7, 11), (8, 12), (3, 4)]
R, V = xring([ "x%d" % v for v in V ], QQ, lex)
E = [(V[i - 1], V[j - 1]) for i, j in E]
x1, x2, x3, x4, x5, x6, x7, x8, x9, x10, x11, x12 = V
I3 = [x**3 - 1 for x in V]
Ig = [x**2 + x*y + y**2 for x, y in E]
I = I3 + Ig
assert groebner(I[:-1], R) == [
x1 + x11 + x12,
x2 - x11,
x3 - x12,
x4 - x12,
x5 + x11 + x12,
x6 - x11,
x7 - x12,
x8 + x11 + x12,
x9 - x11,
x10 + x11 + x12,
x11**2 + x11*x12 + x12**2,
x12**3 - 1,
]
assert groebner(I, R) == [1]
def _do_test_benchmark_katsura_3():
R, x0,x1,x2 = ring("x:3", ZZ, lex)
I = [x0 + 2*x1 + 2*x2 - 1,
x0**2 + 2*x1**2 + 2*x2**2 - x0,
2*x0*x1 + 2*x1*x2 - x1]
assert groebner(I, R) == [
-7 + 7*x0 + 8*x2 + 158*x2**2 - 420*x2**3,
7*x1 + 3*x2 - 79*x2**2 + 210*x2**3,
x2 + x2**2 - 40*x2**3 + 84*x2**4,
]
R, x0,x1,x2 = ring("x:3", ZZ, grlex)
I = [ i.set_ring(R) for i in I ]
assert groebner(I, R) == [
7*x1 + 3*x2 - 79*x2**2 + 210*x2**3,
-x1 + x2 - 3*x2**2 + 5*x1**2,
-x1 - 4*x2 + 10*x1*x2 + 12*x2**2,
-1 + x0 + 2*x1 + 2*x2,
]
def test_benchmark_katsura3_buchberger():
with config.using(groebner='buchberger'):
_do_test_benchmark_katsura_3()
def test_benchmark_katsura3_f5b():
with config.using(groebner='f5b'):
_do_test_benchmark_katsura_3()
def _do_test_benchmark_katsura_4():
R, x0,x1,x2,x3 = ring("x:4", ZZ, lex)
I = [x0 + 2*x1 + 2*x2 + 2*x3 - 1,
x0**2 + 2*x1**2 + 2*x2**2 + 2*x3**2 - x0,
2*x0*x1 + 2*x1*x2 + 2*x2*x3 - x1,
x1**2 + 2*x0*x2 + 2*x1*x3 - x2]
assert groebner(I, R) == [
5913075*x0 - 159690237696*x3**7 + 31246269696*x3**6 + 27439610544*x3**5 - 6475723368*x3**4 - 838935856*x3**3 + 275119624*x3**2 + 4884038*x3 - 5913075,
1971025*x1 - 97197721632*x3**7 + 73975630752*x3**6 - 12121915032*x3**5 - 2760941496*x3**4 + 814792828*x3**3 - 1678512*x3**2 - 9158924*x3,
5913075*x2 + 371438283744*x3**7 - 237550027104*x3**6 + 22645939824*x3**5 + 11520686172*x3**4 - 2024910556*x3**3 - 132524276*x3**2 + 30947828*x3,
128304*x3**8 - 93312*x3**7 + 15552*x3**6 + 3144*x3**5 -
1120*x3**4 + 36*x3**3 + 15*x3**2 - x3,
]
R, x0,x1,x2,x3 = ring("x:4", ZZ, grlex)
I = [ i.set_ring(R) for i in I ]
assert groebner(I, R) == [
393*x1 - 4662*x2**2 + 4462*x2*x3 - 59*x2 + 224532*x3**4 - 91224*x3**3 - 678*x3**2 + 2046*x3,
-x1 + 196*x2**3 - 21*x2**2 + 60*x2*x3 - 18*x2 - 168*x3**3 + 83*x3**2 - 9*x3,
-6*x1 + 1134*x2**2*x3 - 189*x2**2 - 466*x2*x3 + 32*x2 - 630*x3**3 + 57*x3**2 + 51*x3,
33*x1 + 63*x2**2 + 2268*x2*x3**2 - 188*x2*x3 + 34*x2 + 2520*x3**3 - 849*x3**2 + 3*x3,
7*x1**2 - x1 - 7*x2**2 - 24*x2*x3 + 3*x2 - 15*x3**2 + 5*x3,
14*x1*x2 - x1 + 14*x2**2 + 18*x2*x3 - 4*x2 + 6*x3**2 - 2*x3,
14*x1*x3 - x1 + 7*x2**2 + 32*x2*x3 - 4*x2 + 27*x3**2 - 9*x3,
x0 + 2*x1 + 2*x2 + 2*x3 - 1,
]
def test_benchmark_kastura_4_buchberger():
with config.using(groebner='buchberger'):
_do_test_benchmark_katsura_4()
def test_benchmark_kastura_4_f5b():
with config.using(groebner='f5b'):
_do_test_benchmark_katsura_4()
def _do_test_benchmark_czichowski():
R, x,t = ring("x,t", ZZ, lex)
I = [9*x**8 + 36*x**7 - 32*x**6 - 252*x**5 - 78*x**4 + 468*x**3 + 288*x**2 - 108*x + 9,
(-72 - 72*t)*x**7 + (-256 - 252*t)*x**6 + (192 + 192*t)*x**5 + (1280 + 1260*t)*x**4 + (312 + 312*t)*x**3 + (-404*t)*x**2 + (-576 - 576*t)*x + 96 + 108*t]
assert groebner(I, R) == [
3725588592068034903797967297424801242396746870413359539263038139343329273586196480000*x -
160420835591776763325581422211936558925462474417709511019228211783493866564923546661604487873*t**7 -
1406108495478033395547109582678806497509499966197028487131115097902188374051595011248311352864*t**6 -
5241326875850889518164640374668786338033653548841427557880599579174438246266263602956254030352*t**5 -
10758917262823299139373269714910672770004760114329943852726887632013485035262879510837043892416*t**4 -
13119383576444715672578819534846747735372132018341964647712009275306635391456880068261130581248*t**3 -
9491412317016197146080450036267011389660653495578680036574753839055748080962214787557853941760*t**2 -
3767520915562795326943800040277726397326609797172964377014046018280260848046603967211258368000*t -
632314652371226552085897259159210286886724229880266931574701654721512325555116066073245696000,
610733380717522355121*t**8 +
6243748742141230639968*t**7 +
27761407182086143225024*t**6 +
70066148869420956398592*t**5 +
109701225644313784229376*t**4 +
109009005495588442152960*t**3 +
67072101084384786432000*t**2 +
23339979742629593088000*t +
3513592776846090240000,
]
R, x,t = ring("x,t", ZZ, grlex)
I = [ i.set_ring(R) for i in I ]
assert groebner(I, R) == [
16996618586000601590732959134095643086442*t**3*x -
32936701459297092865176560282688198064839*t**3 +
78592411049800639484139414821529525782364*t**2*x -
120753953358671750165454009478961405619916*t**2 +
120988399875140799712152158915653654637280*t*x -
144576390266626470824138354942076045758736*t +
60017634054270480831259316163620768960*x**2 +
61976058033571109604821862786675242894400*x -
56266268491293858791834120380427754600960,
576689018321912327136790519059646508441672750656050290242749*t**4 +
2326673103677477425562248201573604572527893938459296513327336*t**3 +
110743790416688497407826310048520299245819959064297990236000*t**2*x +
3308669114229100853338245486174247752683277925010505284338016*t**2 +
323150205645687941261103426627818874426097912639158572428800*t*x +
1914335199925152083917206349978534224695445819017286960055680*t +
861662882561803377986838989464278045397192862768588480000*x**2 +
235296483281783440197069672204341465480107019878814196672000*x +
361850798943225141738895123621685122544503614946436727532800,
-117584925286448670474763406733005510014188341867*t**3 +
68566565876066068463853874568722190223721653044*t**2*x -
435970731348366266878180788833437896139920683940*t**2 +
196297602447033751918195568051376792491869233408*t*x -
525011527660010557871349062870980202067479780112*t +
517905853447200553360289634770487684447317120*x**3 +
569119014870778921949288951688799397569321920*x**2 +
138877356748142786670127389526667463202210102080*x -
205109210539096046121625447192779783475018619520,
-3725142681462373002731339445216700112264527*t**3 +
583711207282060457652784180668273817487940*t**2*x -
12381382393074485225164741437227437062814908*t**2 +
151081054097783125250959636747516827435040*t*x**2 +
1814103857455163948531448580501928933873280*t*x -
13353115629395094645843682074271212731433648*t +
236415091385250007660606958022544983766080*x**2 +
1390443278862804663728298060085399578417600*x -
4716885828494075789338754454248931750698880,
]
# NOTE: This is very slow (> 2 minutes on 3.4 GHz) without GMPY
@slow
def test_benchmark_czichowski_buchberger():
with config.using(groebner='buchberger'):
_do_test_benchmark_czichowski()
def test_benchmark_czichowski_f5b():
with config.using(groebner='f5b'):
_do_test_benchmark_czichowski()
def _do_test_benchmark_cyclic_4():
R, a,b,c,d = ring("a,b,c,d", ZZ, lex)
I = [a + b + c + d,
a*b + a*d + b*c + b*d,
a*b*c + a*b*d + a*c*d + b*c*d,
a*b*c*d - 1]
assert groebner(I, R) == [
4*a + 3*d**9 - 4*d**5 - 3*d,
4*b + 4*c - 3*d**9 + 4*d**5 + 7*d,
4*c**2 + 3*d**10 - 4*d**6 - 3*d**2,
4*c*d**4 + 4*c - d**9 + 4*d**5 + 5*d, d**12 - d**8 - d**4 + 1
]
R, a,b,c,d = ring("a,b,c,d", ZZ, grlex)
I = [ i.set_ring(R) for i in I ]
assert groebner(I, R) == [
3*b*c - c**2 + d**6 - 3*d**2,
-b + 3*c**2*d**3 - c - d**5 - 4*d,
-b + 3*c*d**4 + 2*c + 2*d**5 + 2*d,
c**4 + 2*c**2*d**2 - d**4 - 2,
c**3*d + c*d**3 + d**4 + 1,
b*c**2 - c**3 - c**2*d - 2*c*d**2 - d**3,
b**2 - c**2, b*d + c**2 + c*d + d**2,
a + b + c + d
]
def test_benchmark_cyclic_4_buchberger():
with config.using(groebner='buchberger'):
_do_test_benchmark_cyclic_4()
def test_benchmark_cyclic_4_f5b():
with config.using(groebner='f5b'):
_do_test_benchmark_cyclic_4()
def test_sig_key():
s1 = sig((0,) * 3, 2)
s2 = sig((1,) * 3, 4)
s3 = sig((2,) * 3, 2)
assert sig_key(s1, lex) > sig_key(s2, lex)
assert sig_key(s2, lex) < sig_key(s3, lex)
def test_lbp_key():
R, x,y,z,t = ring("x,y,z,t", ZZ, lex)
p1 = lbp(sig((0,) * 4, 3), R.zero, 12)
p2 = lbp(sig((0,) * 4, 4), R.zero, 13)
p3 = lbp(sig((0,) * 4, 4), R.zero, 12)
assert lbp_key(p1) > lbp_key(p2)
assert lbp_key(p2) < lbp_key(p3)
def test_critical_pair():
# from cyclic4 with grlex
R, x,y,z,t = ring("x,y,z,t", QQ, grlex)
p1 = (((0, 0, 0, 0), 4), y*z*t**2 + z**2*t**2 - t**4 - 1, 4)
q1 = (((0, 0, 0, 0), 2), -y**2 - y*t - z*t - t**2, 2)
p2 = (((0, 0, 0, 2), 3), z**3*t**2 + z**2*t**3 - z - t, 5)
q2 = (((0, 0, 2, 2), 2), y*z + z*t**5 + z*t + t**6, 13)
assert critical_pair(p1, q1, R) == (
((0, 0, 1, 2), 2), ((0, 0, 1, 2), QQ(-1, 1)), (((0, 0, 0, 0), 2), -y**2 - y*t - z*t - t**2, 2),
((0, 1, 0, 0), 4), ((0, 1, 0, 0), QQ(1, 1)), (((0, 0, 0, 0), 4), y*z*t**2 + z**2*t**2 - t**4 - 1, 4)
)
assert critical_pair(p2, q2, R) == (
((0, 0, 4, 2), 2), ((0, 0, 2, 0), QQ(1, 1)), (((0, 0, 2, 2), 2), y*z + z*t**5 + z*t + t**6, 13),
((0, 0, 0, 5), 3), ((0, 0, 0, 3), QQ(1, 1)), (((0, 0, 0, 2), 3), z**3*t**2 + z**2*t**3 - z - t, 5)
)
def test_cp_key():
# from cyclic4 with grlex
R, x,y,z,t = ring("x,y,z,t", QQ, grlex)
p1 = (((0, 0, 0, 0), 4), y*z*t**2 + z**2*t**2 - t**4 - 1, 4)
q1 = (((0, 0, 0, 0), 2), -y**2 - y*t - z*t - t**2, 2)
p2 = (((0, 0, 0, 2), 3), z**3*t**2 + z**2*t**3 - z - t, 5)
q2 = (((0, 0, 2, 2), 2), y*z + z*t**5 + z*t + t**6, 13)
cp1 = critical_pair(p1, q1, R)
cp2 = critical_pair(p2, q2, R)
assert cp_key(cp1, R) < cp_key(cp2, R)
cp1 = critical_pair(p1, p2, R)
cp2 = critical_pair(q1, q2, R)
assert cp_key(cp1, R) < cp_key(cp2, R)
def test_is_rewritable_or_comparable():
# from katsura4 with grlex
R, x,y,z,t = ring("x,y,z,t", QQ, grlex)
p = lbp(sig((0, 0, 2, 1), 2), R.zero, 2)
B = [lbp(sig((0, 0, 0, 1), 2), QQ(2,45)*y**2 + QQ(1,5)*y*z + QQ(5,63)*y*t + z**2*t + QQ(4,45)*z**2 + QQ(76,35)*z*t**2 - QQ(32,105)*z*t + QQ(13,7)*t**3 - QQ(13,21)*t**2, 6)]
# rewritable:
assert is_rewritable_or_comparable(Sign(p), Num(p), B) is True
p = lbp(sig((0, 1, 1, 0), 2), R.zero, 7)
B = [lbp(sig((0, 0, 0, 0), 3), QQ(10,3)*y*z + QQ(4,3)*y*t - QQ(1,3)*y + 4*z**2 + QQ(22,3)*z*t - QQ(4,3)*z + 4*t**2 - QQ(4,3)*t, 3)]
# comparable:
assert is_rewritable_or_comparable(Sign(p), Num(p), B) is True
def test_f5_reduce():
# katsura3 with lex
R, x,y,z = ring("x,y,z", QQ, lex)
F = [(((0, 0, 0), 1), x + 2*y + 2*z - 1, 1),
(((0, 0, 0), 2), 6*y**2 + 8*y*z - 2*y + 6*z**2 - 2*z, 2),
(((0, 0, 0), 3), QQ(10,3)*y*z - QQ(1,3)*y + 4*z**2 - QQ(4,3)*z, 3),
(((0, 0, 1), 2), y + 30*z**3 - QQ(79,7)*z**2 + QQ(3,7)*z, 4),
(((0, 0, 2), 2), z**4 - QQ(10,21)*z**3 + QQ(1,84)*z**2 + QQ(1,84)*z, 5)]
cp = critical_pair(F[0], F[1], R)
s = s_poly(cp)
assert f5_reduce(s, F) == (((0, 2, 0), 1), R.zero, 1)
s = lbp(sig(Sign(s)[0], 100), Polyn(s), Num(s))
assert f5_reduce(s, F) == s
def test_representing_matrices():
R, x,y = ring("x,y", QQ, grlex)
basis = [(0, 0), (0, 1), (1, 0), (1, 1)]
F = [x**2 - x - 3*y + 1, -2*x + y**2 + y - 1]
assert _representing_matrices(basis, F, R) == [
[[QQ(0, 1), QQ(0, 1),-QQ(1, 1), QQ(3, 1)],
[QQ(0, 1), QQ(0, 1), QQ(3, 1),-QQ(4, 1)],
[QQ(1, 1), QQ(0, 1), QQ(1, 1), QQ(6, 1)],
[QQ(0, 1), QQ(1, 1), QQ(0, 1), QQ(1, 1)]],
[[QQ(0, 1), QQ(1, 1), QQ(0, 1),-QQ(2, 1)],
[QQ(1, 1),-QQ(1, 1), QQ(0, 1), QQ(6, 1)],
[QQ(0, 1), QQ(2, 1), QQ(0, 1), QQ(3, 1)],
[QQ(0, 1), QQ(0, 1), QQ(1, 1),-QQ(1, 1)]]]
def test_groebner_lcm():
R, x,y,z = ring("x,y,z", ZZ)
assert groebner_lcm(x**2 - y**2, x - y) == x**2 - y**2
assert groebner_lcm(2*x**2 - 2*y**2, 2*x - 2*y) == 2*x**2 - 2*y**2
R, x,y,z = ring("x,y,z", QQ)
assert groebner_lcm(x**2 - y**2, x - y) == x**2 - y**2
assert groebner_lcm(2*x**2 - 2*y**2, 2*x - 2*y) == 2*x**2 - 2*y**2
R, x,y = ring("x,y", ZZ)
assert groebner_lcm(x**2*y, x*y**2) == x**2*y**2
f = 2*x*y**5 - 3*x*y**4 - 2*x*y**3 + 3*x*y**2
g = y**5 - 2*y**3 + y
h = 2*x*y**7 - 3*x*y**6 - 4*x*y**5 + 6*x*y**4 + 2*x*y**3 - 3*x*y**2
assert groebner_lcm(f, g) == h
f = x**3 - 3*x**2*y - 9*x*y**2 - 5*y**3
g = x**4 + 6*x**3*y + 12*x**2*y**2 + 10*x*y**3 + 3*y**4
h = x**5 + x**4*y - 18*x**3*y**2 - 50*x**2*y**3 - 47*x*y**4 - 15*y**5
assert groebner_lcm(f, g) == h
def test_groebner_gcd():
R, x,y,z = ring("x,y,z", ZZ)
assert groebner_gcd(x**2 - y**2, x - y) == x - y
assert groebner_gcd(2*x**2 - 2*y**2, 2*x - 2*y) == 2*x - 2*y
R, x,y,z = ring("x,y,z", QQ)
assert groebner_gcd(x**2 - y**2, x - y) == x - y
assert groebner_gcd(2*x**2 - 2*y**2, 2*x - 2*y) == x - y
def test_is_groebner():
R, x,y = ring("x,y", QQ, grlex)
valid_groebner = [x**2, x*y, -QQ(1,2)*x + y**2]
invalid_groebner = [x**3, x*y, -QQ(1,2)*x + y**2]
assert is_groebner(valid_groebner, R) is True
assert is_groebner(invalid_groebner, R) is False
|
6e4b6411645acf33a7bec9f0e38094d9e6fd956c1d01e07b53cdc4f59f4d2676
|
"""Tests for OO layer of several polynomial representations. """
from sympy.core.compatibility import long
from sympy.polys.domains import ZZ, QQ
from sympy.polys.polyclasses import DMP, DMF, ANP
from sympy.polys.polyerrors import ExactQuotientFailed, NotInvertible
from sympy.polys.specialpolys import f_polys
from sympy.utilities.pytest import raises
f_0, f_1, f_2, f_3, f_4, f_5, f_6 = [ f.to_dense() for f in f_polys() ]
def test_DMP___init__():
f = DMP([[0], [], [0, 1, 2], [3]], ZZ)
assert f.rep == [[1, 2], [3]]
assert f.dom == ZZ
assert f.lev == 1
f = DMP([[1, 2], [3]], ZZ, 1)
assert f.rep == [[1, 2], [3]]
assert f.dom == ZZ
assert f.lev == 1
f = DMP({(1, 1): 1, (0, 0): 2}, ZZ, 1)
assert f.rep == [[1, 0], [2]]
assert f.dom == ZZ
assert f.lev == 1
def test_DMP___eq__():
assert DMP([[ZZ(1), ZZ(2)], [ZZ(3)]], ZZ) == \
DMP([[ZZ(1), ZZ(2)], [ZZ(3)]], ZZ)
assert DMP([[ZZ(1), ZZ(2)], [ZZ(3)]], ZZ) == \
DMP([[QQ(1), QQ(2)], [QQ(3)]], QQ)
assert DMP([[QQ(1), QQ(2)], [QQ(3)]], QQ) == \
DMP([[ZZ(1), ZZ(2)], [ZZ(3)]], ZZ)
assert DMP([[[ZZ(1)]]], ZZ) != DMP([[ZZ(1)]], ZZ)
assert DMP([[ZZ(1)]], ZZ) != DMP([[[ZZ(1)]]], ZZ)
def test_DMP___bool__():
assert bool(DMP([[]], ZZ)) is False
assert bool(DMP([[1]], ZZ)) is True
def test_DMP_to_dict():
f = DMP([[3], [], [2], [], [8]], ZZ)
assert f.to_dict() == \
{(4, 0): 3, (2, 0): 2, (0, 0): 8}
assert f.to_sympy_dict() == \
{(4, 0): ZZ.to_sympy(3), (2, 0): ZZ.to_sympy(2), (0, 0):
ZZ.to_sympy(8)}
def test_DMP_properties():
assert DMP([[]], ZZ).is_zero is True
assert DMP([[1]], ZZ).is_zero is False
assert DMP([[1]], ZZ).is_one is True
assert DMP([[2]], ZZ).is_one is False
assert DMP([[1]], ZZ).is_ground is True
assert DMP([[1], [2], [1]], ZZ).is_ground is False
assert DMP([[1], [2, 0], [1, 0]], ZZ).is_sqf is True
assert DMP([[1], [2, 0], [1, 0, 0]], ZZ).is_sqf is False
assert DMP([[1, 2], [3]], ZZ).is_monic is True
assert DMP([[2, 2], [3]], ZZ).is_monic is False
assert DMP([[1, 2], [3]], ZZ).is_primitive is True
assert DMP([[2, 4], [6]], ZZ).is_primitive is False
def test_DMP_arithmetics():
f = DMP([[2], [2, 0]], ZZ)
assert f.mul_ground(2) == DMP([[4], [4, 0]], ZZ)
assert f.quo_ground(2) == DMP([[1], [1, 0]], ZZ)
raises(ExactQuotientFailed, lambda: f.exquo_ground(3))
f = DMP([[-5]], ZZ)
g = DMP([[5]], ZZ)
assert f.abs() == g
assert abs(f) == g
assert g.neg() == f
assert -g == f
h = DMP([[]], ZZ)
assert f.add(g) == h
assert f + g == h
assert g + f == h
assert f + 5 == h
assert 5 + f == h
h = DMP([[-10]], ZZ)
assert f.sub(g) == h
assert f - g == h
assert g - f == -h
assert f - 5 == h
assert 5 - f == -h
h = DMP([[-25]], ZZ)
assert f.mul(g) == h
assert f * g == h
assert g * f == h
assert f * 5 == h
assert 5 * f == h
h = DMP([[25]], ZZ)
assert f.sqr() == h
assert f.pow(2) == h
assert f**2 == h
raises(TypeError, lambda: f.pow('x'))
f = DMP([[1], [], [1, 0, 0]], ZZ)
g = DMP([[2], [-2, 0]], ZZ)
q = DMP([[2], [2, 0]], ZZ)
r = DMP([[8, 0, 0]], ZZ)
assert f.pdiv(g) == (q, r)
assert f.pquo(g) == q
assert f.prem(g) == r
raises(ExactQuotientFailed, lambda: f.pexquo(g))
f = DMP([[1], [], [1, 0, 0]], ZZ)
g = DMP([[1], [-1, 0]], ZZ)
q = DMP([[1], [1, 0]], ZZ)
r = DMP([[2, 0, 0]], ZZ)
assert f.div(g) == (q, r)
assert f.quo(g) == q
assert f.rem(g) == r
assert divmod(f, g) == (q, r)
assert f // g == q
assert f % g == r
raises(ExactQuotientFailed, lambda: f.exquo(g))
def test_DMP_functionality():
f = DMP([[1], [2, 0], [1, 0, 0]], ZZ)
g = DMP([[1], [1, 0]], ZZ)
h = DMP([[1]], ZZ)
assert f.degree() == 2
assert f.degree_list() == (2, 2)
assert f.total_degree() == 2
assert f.LC() == ZZ(1)
assert f.TC() == ZZ(0)
assert f.nth(1, 1) == ZZ(2)
raises(TypeError, lambda: f.nth(0, 'x'))
assert f.max_norm() == 2
assert f.l1_norm() == 4
u = DMP([[2], [2, 0]], ZZ)
assert f.diff(m=1, j=0) == u
assert f.diff(m=1, j=1) == u
raises(TypeError, lambda: f.diff(m='x', j=0))
u = DMP([1, 2, 1], ZZ)
v = DMP([1, 2, 1], ZZ)
assert f.eval(a=1, j=0) == u
assert f.eval(a=1, j=1) == v
assert f.eval(1).eval(1) == ZZ(4)
assert f.cofactors(g) == (g, g, h)
assert f.gcd(g) == g
assert f.lcm(g) == f
u = DMP([[QQ(45), QQ(30), QQ(5)]], QQ)
v = DMP([[QQ(1), QQ(2, 3), QQ(1, 9)]], QQ)
assert u.monic() == v
assert (4*f).content() == ZZ(4)
assert (4*f).primitive() == (ZZ(4), f)
f = DMP([[1], [2], [3], [4], [5], [6]], ZZ)
assert f.trunc(3) == DMP([[1], [-1], [], [1], [-1], []], ZZ)
f = DMP(f_4, ZZ)
assert f.sqf_part() == -f
assert f.sqf_list() == (ZZ(-1), [(-f, 1)])
f = DMP([[-1], [], [], [5]], ZZ)
g = DMP([[3, 1], [], []], ZZ)
h = DMP([[45, 30, 5]], ZZ)
r = DMP([675, 675, 225, 25], ZZ)
assert f.subresultants(g) == [f, g, h]
assert f.resultant(g) == r
f = DMP([1, 3, 9, -13], ZZ)
assert f.discriminant() == -11664
f = DMP([QQ(2), QQ(0)], QQ)
g = DMP([QQ(1), QQ(0), QQ(-16)], QQ)
s = DMP([QQ(1, 32), QQ(0)], QQ)
t = DMP([QQ(-1, 16)], QQ)
h = DMP([QQ(1)], QQ)
assert f.half_gcdex(g) == (s, h)
assert f.gcdex(g) == (s, t, h)
assert f.invert(g) == s
f = DMP([[1], [2], [3]], QQ)
raises(ValueError, lambda: f.half_gcdex(f))
raises(ValueError, lambda: f.gcdex(f))
raises(ValueError, lambda: f.invert(f))
f = DMP([1, 0, 20, 0, 150, 0, 500, 0, 625, -2, 0, -10, 9], ZZ)
g = DMP([1, 0, 0, -2, 9], ZZ)
h = DMP([1, 0, 5, 0], ZZ)
assert g.compose(h) == f
assert f.decompose() == [g, h]
f = DMP([[1], [2], [3]], QQ)
raises(ValueError, lambda: f.decompose())
raises(ValueError, lambda: f.sturm())
def test_DMP_exclude():
f = [[[[[[[[[[[[[[[[[[[[[[[[[[1]], [[]]]]]]]]]]]]]]]]]]]]]]]]]]
J = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17,
18, 19, 20, 21, 22, 24, 25]
assert DMP(f, ZZ).exclude() == (J, DMP([1, 0], ZZ))
assert DMP([[1], [1, 0]], ZZ).exclude() == ([], DMP([[1], [1, 0]], ZZ))
def test_DMF__init__():
f = DMF(([[0], [], [0, 1, 2], [3]], [[1, 2, 3]]), ZZ)
assert f.num == [[1, 2], [3]]
assert f.den == [[1, 2, 3]]
assert f.lev == 1
assert f.dom == ZZ
f = DMF(([[1, 2], [3]], [[1, 2, 3]]), ZZ, 1)
assert f.num == [[1, 2], [3]]
assert f.den == [[1, 2, 3]]
assert f.lev == 1
assert f.dom == ZZ
f = DMF(([[-1], [-2]], [[3], [-4]]), ZZ)
assert f.num == [[-1], [-2]]
assert f.den == [[3], [-4]]
assert f.lev == 1
assert f.dom == ZZ
f = DMF(([[1], [2]], [[-3], [4]]), ZZ)
assert f.num == [[-1], [-2]]
assert f.den == [[3], [-4]]
assert f.lev == 1
assert f.dom == ZZ
f = DMF(([[1], [2]], [[-3], [4]]), ZZ)
assert f.num == [[-1], [-2]]
assert f.den == [[3], [-4]]
assert f.lev == 1
assert f.dom == ZZ
f = DMF(([[]], [[-3], [4]]), ZZ)
assert f.num == [[]]
assert f.den == [[1]]
assert f.lev == 1
assert f.dom == ZZ
f = DMF(17, ZZ, 1)
assert f.num == [[17]]
assert f.den == [[1]]
assert f.lev == 1
assert f.dom == ZZ
f = DMF(([[1], [2]]), ZZ)
assert f.num == [[1], [2]]
assert f.den == [[1]]
assert f.lev == 1
assert f.dom == ZZ
f = DMF([[0], [], [0, 1, 2], [3]], ZZ)
assert f.num == [[1, 2], [3]]
assert f.den == [[1]]
assert f.lev == 1
assert f.dom == ZZ
f = DMF({(1, 1): 1, (0, 0): 2}, ZZ, 1)
assert f.num == [[1, 0], [2]]
assert f.den == [[1]]
assert f.lev == 1
assert f.dom == ZZ
f = DMF(([[QQ(1)], [QQ(2)]], [[-QQ(3)], [QQ(4)]]), QQ)
assert f.num == [[-QQ(1)], [-QQ(2)]]
assert f.den == [[QQ(3)], [-QQ(4)]]
assert f.lev == 1
assert f.dom == QQ
f = DMF(([[QQ(1, 5)], [QQ(2, 5)]], [[-QQ(3, 7)], [QQ(4, 7)]]), QQ)
assert f.num == [[-QQ(7)], [-QQ(14)]]
assert f.den == [[QQ(15)], [-QQ(20)]]
assert f.lev == 1
assert f.dom == QQ
raises(ValueError, lambda: DMF(([1], [[1]]), ZZ))
raises(ZeroDivisionError, lambda: DMF(([1], []), ZZ))
def test_DMF__bool__():
assert bool(DMF([[]], ZZ)) is False
assert bool(DMF([[1]], ZZ)) is True
def test_DMF_properties():
assert DMF([[]], ZZ).is_zero is True
assert DMF([[]], ZZ).is_one is False
assert DMF([[1]], ZZ).is_zero is False
assert DMF([[1]], ZZ).is_one is True
assert DMF(([[1]], [[2]]), ZZ).is_one is False
def test_DMF_arithmetics():
f = DMF([[7], [-9]], ZZ)
g = DMF([[-7], [9]], ZZ)
assert f.neg() == -f == g
f = DMF(([[1]], [[1], []]), ZZ)
g = DMF(([[1]], [[1, 0]]), ZZ)
h = DMF(([[1], [1, 0]], [[1, 0], []]), ZZ)
assert f.add(g) == f + g == h
assert g.add(f) == g + f == h
h = DMF(([[-1], [1, 0]], [[1, 0], []]), ZZ)
assert f.sub(g) == f - g == h
h = DMF(([[1]], [[1, 0], []]), ZZ)
assert f.mul(g) == f*g == h
assert g.mul(f) == g*f == h
h = DMF(([[1, 0]], [[1], []]), ZZ)
assert f.quo(g) == f/g == h
h = DMF(([[1]], [[1], [], [], []]), ZZ)
assert f.pow(3) == f**3 == h
h = DMF(([[1]], [[1, 0, 0, 0]]), ZZ)
assert g.pow(3) == g**3 == h
def test_ANP___init__():
rep = [QQ(1), QQ(1)]
mod = [QQ(1), QQ(0), QQ(1)]
f = ANP(rep, mod, QQ)
assert f.rep == [QQ(1), QQ(1)]
assert f.mod == [QQ(1), QQ(0), QQ(1)]
assert f.dom == QQ
rep = {1: QQ(1), 0: QQ(1)}
mod = {2: QQ(1), 0: QQ(1)}
f = ANP(rep, mod, QQ)
assert f.rep == [QQ(1), QQ(1)]
assert f.mod == [QQ(1), QQ(0), QQ(1)]
assert f.dom == QQ
f = ANP(1, mod, QQ)
assert f.rep == [QQ(1)]
assert f.mod == [QQ(1), QQ(0), QQ(1)]
assert f.dom == QQ
def test_ANP___eq__():
a = ANP([QQ(1), QQ(1)], [QQ(1), QQ(0), QQ(1)], QQ)
b = ANP([QQ(1), QQ(1)], [QQ(1), QQ(0), QQ(2)], QQ)
assert (a == a) is True
assert (a != a) is False
assert (a == b) is False
assert (a != b) is True
b = ANP([QQ(1), QQ(2)], [QQ(1), QQ(0), QQ(1)], QQ)
assert (a == b) is False
assert (a != b) is True
def test_ANP___bool__():
assert bool(ANP([], [QQ(1), QQ(0), QQ(1)], QQ)) is False
assert bool(ANP([QQ(1)], [QQ(1), QQ(0), QQ(1)], QQ)) is True
def test_ANP_properties():
mod = [QQ(1), QQ(0), QQ(1)]
assert ANP([QQ(0)], mod, QQ).is_zero is True
assert ANP([QQ(1)], mod, QQ).is_zero is False
assert ANP([QQ(1)], mod, QQ).is_one is True
assert ANP([QQ(2)], mod, QQ).is_one is False
def test_ANP_arithmetics():
mod = [QQ(1), QQ(0), QQ(0), QQ(-2)]
a = ANP([QQ(2), QQ(-1), QQ(1)], mod, QQ)
b = ANP([QQ(1), QQ(2)], mod, QQ)
c = ANP([QQ(-2), QQ(1), QQ(-1)], mod, QQ)
assert a.neg() == -a == c
c = ANP([QQ(2), QQ(0), QQ(3)], mod, QQ)
assert a.add(b) == a + b == c
assert b.add(a) == b + a == c
c = ANP([QQ(2), QQ(-2), QQ(-1)], mod, QQ)
assert a.sub(b) == a - b == c
c = ANP([QQ(-2), QQ(2), QQ(1)], mod, QQ)
assert b.sub(a) == b - a == c
c = ANP([QQ(3), QQ(-1), QQ(6)], mod, QQ)
assert a.mul(b) == a*b == c
assert b.mul(a) == b*a == c
c = ANP([QQ(-1, 43), QQ(9, 43), QQ(5, 43)], mod, QQ)
assert a.pow(0) == a**(0) == ANP(1, mod, QQ)
assert a.pow(1) == a**(1) == a
assert a.pow(-1) == a**(-1) == c
assert a.quo(a) == a.mul(a.pow(-1)) == a*a**(-1) == ANP(1, mod, QQ)
c = ANP([], [1, 0, 0, -2], QQ)
r1 = a.rem(b)
(q, r2) = a.div(b)
assert r1 == r2 == c == a % b
raises(NotInvertible, lambda: a.div(c))
raises(NotInvertible, lambda: a.rem(c))
# Comparison with "hard-coded" value fails despite looking identical
# from sympy import Rational
# c = ANP([Rational(11, 10), Rational(-1, 5), Rational(-3, 5)], [1, 0, 0, -2], QQ)
assert q == a/b # == c
def test_ANP_unify():
mod = [QQ(1), QQ(0), QQ(-2)]
a = ANP([QQ(1)], mod, QQ)
b = ANP([ZZ(1)], mod, ZZ)
assert a.unify(b)[0] == QQ
assert b.unify(a)[0] == QQ
assert a.unify(a)[0] == QQ
assert b.unify(b)[0] == ZZ
def test___hash__():
# issue 5571
# Make sure int vs. long doesn't affect hashing with Python ground types
assert DMP([[1, 2], [3]], ZZ) == DMP([[long(1), long(2)], [long(3)]], ZZ)
assert hash(DMP([[1, 2], [3]], ZZ)) == hash(DMP([[long(1), long(2)], [long(3)]], ZZ))
assert DMF(
([[1, 2], [3]], [[1]]), ZZ) == DMF(([[long(1), long(2)], [long(3)]], [[long(1)]]), ZZ)
assert hash(DMF(([[1, 2], [3]], [[1]]), ZZ)) == hash(DMF(([[long(1),
long(2)], [long(3)]], [[long(1)]]), ZZ))
assert ANP([1, 1], [1, 0, 1], ZZ) == ANP([long(1), long(1)], [long(1), long(0), long(1)], ZZ)
assert hash(
ANP([1, 1], [1, 0, 1], ZZ)) == hash(ANP([long(1), long(1)], [long(1), long(0), long(1)], ZZ))
|
ac9afb17034eea0c40bc50a0acefe01358d7cd0745c12688d2ac1ab2b3de3038
|
from sympy import var, sturm, subresultants, prem, pquo
from sympy.matrices import Matrix
from sympy.polys.subresultants_qq_zz import (sylvester, res, res_q, res_z, bezout,
subresultants_sylv, modified_subresultants_sylv,
subresultants_bezout, modified_subresultants_bezout,
backward_eye,
sturm_pg, sturm_q, sturm_amv, euclid_pg, euclid_q,
euclid_amv, modified_subresultants_pg, subresultants_pg,
subresultants_amv_q, quo_z, rem_z, subresultants_amv,
modified_subresultants_amv, subresultants_rem,
subresultants_vv, subresultants_vv_2)
def test_sylvester():
x = var('x')
assert sylvester(x**3 -7, 0, x) == sylvester(x**3 -7, 0, x, 1) == Matrix([[0]])
assert sylvester(0, x**3 -7, x) == sylvester(0, x**3 -7, x, 1) == Matrix([[0]])
assert sylvester(x**3 -7, 0, x, 2) == Matrix([[0]])
assert sylvester(0, x**3 -7, x, 2) == Matrix([[0]])
assert sylvester(x**3 -7, 7, x).det() == sylvester(x**3 -7, 7, x, 1).det() == 343
assert sylvester(7, x**3 -7, x).det() == sylvester(7, x**3 -7, x, 1).det() == 343
assert sylvester(x**3 -7, 7, x, 2).det() == -343
assert sylvester(7, x**3 -7, x, 2).det() == 343
assert sylvester(3, 7, x).det() == sylvester(3, 7, x, 1).det() == sylvester(3, 7, x, 2).det() == 1
assert sylvester(3, 0, x).det() == sylvester(3, 0, x, 1).det() == sylvester(3, 0, x, 2).det() == 1
assert sylvester(x - 3, x - 8, x) == sylvester(x - 3, x - 8, x, 1) == sylvester(x - 3, x - 8, x, 2) == Matrix([[1, -3], [1, -8]])
assert sylvester(x**3 - 7*x + 7, 3*x**2 - 7, x) == sylvester(x**3 - 7*x + 7, 3*x**2 - 7, x, 1) == Matrix([[1, 0, -7, 7, 0], [0, 1, 0, -7, 7], [3, 0, -7, 0, 0], [0, 3, 0, -7, 0], [0, 0, 3, 0, -7]])
assert sylvester(x**3 - 7*x + 7, 3*x**2 - 7, x, 2) == Matrix([
[1, 0, -7, 7, 0, 0], [0, 3, 0, -7, 0, 0], [0, 1, 0, -7, 7, 0], [0, 0, 3, 0, -7, 0], [0, 0, 1, 0, -7, 7], [0, 0, 0, 3, 0, -7]])
def test_subresultants_sylv():
x = var('x')
p = x**8 + x**6 - 3*x**4 - 3*x**3 + 8*x**2 + 2*x - 5
q = 3*x**6 + 5*x**4 - 4*x**2 - 9*x + 21
assert subresultants_sylv(p, q, x) == subresultants(p, q, x)
assert subresultants_sylv(p, q, x)[-1] == res(p, q, x)
assert subresultants_sylv(p, q, x) != euclid_amv(p, q, x)
amv_factors = [1, 1, -1, 1, -1, 1]
assert subresultants_sylv(p, q, x) == [i*j for i, j in zip(amv_factors, modified_subresultants_amv(p, q, x))]
p = x**3 - 7*x + 7
q = 3*x**2 - 7
assert subresultants_sylv(p, q, x) == euclid_amv(p, q, x)
def test_modified_subresultants_sylv():
x = var('x')
p = x**8 + x**6 - 3*x**4 - 3*x**3 + 8*x**2 + 2*x - 5
q = 3*x**6 + 5*x**4 - 4*x**2 - 9*x + 21
amv_factors = [1, 1, -1, 1, -1, 1]
assert modified_subresultants_sylv(p, q, x) == [i*j for i, j in zip(amv_factors, subresultants_amv(p, q, x))]
assert modified_subresultants_sylv(p, q, x)[-1] != res_q(p + x**8, q, x)
assert modified_subresultants_sylv(p, q, x) != sturm_amv(p, q, x)
p = x**3 - 7*x + 7
q = 3*x**2 - 7
assert modified_subresultants_sylv(p, q, x) == sturm_amv(p, q, x)
assert modified_subresultants_sylv(-p, q, x) != sturm_amv(-p, q, x)
def test_res():
x = var('x')
assert res(3, 5, x) == 1
def test_res_q():
x = var('x')
assert res_q(3, 5, x) == 1
def test_res_z():
x = var('x')
assert res_z(3, 5, x) == 1
assert res(3, 5, x) == res_q(3, 5, x) == res_z(3, 5, x)
def test_bezout():
x = var('x')
p = -2*x**5+7*x**3+9*x**2-3*x+1
q = -10*x**4+21*x**2+18*x-3
assert bezout(p, q, x, 'bz').det() == sylvester(p, q, x, 2).det()
assert bezout(p, q, x, 'bz').det() != sylvester(p, q, x, 1).det()
assert bezout(p, q, x, 'prs') == backward_eye(5) * bezout(p, q, x, 'bz') * backward_eye(5)
def test_subresultants_bezout():
x = var('x')
p = x**8 + x**6 - 3*x**4 - 3*x**3 + 8*x**2 + 2*x - 5
q = 3*x**6 + 5*x**4 - 4*x**2 - 9*x + 21
assert subresultants_bezout(p, q, x) == subresultants(p, q, x)
assert subresultants_bezout(p, q, x)[-1] == sylvester(p, q, x).det()
assert subresultants_bezout(p, q, x) != euclid_amv(p, q, x)
amv_factors = [1, 1, -1, 1, -1, 1]
assert subresultants_bezout(p, q, x) == [i*j for i, j in zip(amv_factors, modified_subresultants_amv(p, q, x))]
p = x**3 - 7*x + 7
q = 3*x**2 - 7
assert subresultants_bezout(p, q, x) == euclid_amv(p, q, x)
def test_modified_subresultants_bezout():
x = var('x')
p = x**8 + x**6 - 3*x**4 - 3*x**3 + 8*x**2 + 2*x - 5
q = 3*x**6 + 5*x**4 - 4*x**2 - 9*x + 21
amv_factors = [1, 1, -1, 1, -1, 1]
assert modified_subresultants_bezout(p, q, x) == [i*j for i, j in zip(amv_factors, subresultants_amv(p, q, x))]
assert modified_subresultants_bezout(p, q, x)[-1] != sylvester(p + x**8, q, x).det()
assert modified_subresultants_bezout(p, q, x) != sturm_amv(p, q, x)
p = x**3 - 7*x + 7
q = 3*x**2 - 7
assert modified_subresultants_bezout(p, q, x) == sturm_amv(p, q, x)
assert modified_subresultants_bezout(-p, q, x) != sturm_amv(-p, q, x)
def test_sturm_pg():
x = var('x')
p = x**8 + x**6 - 3*x**4 - 3*x**3 + 8*x**2 + 2*x - 5
q = 3*x**6 + 5*x**4 - 4*x**2 - 9*x + 21
assert sturm_pg(p, q, x)[-1] != sylvester(p, q, x, 2).det()
sam_factors = [1, 1, -1, -1, 1, 1]
assert sturm_pg(p, q, x) == [i*j for i,j in zip(sam_factors, euclid_pg(p, q, x))]
p = -9*x**5 - 5*x**3 - 9
q = -45*x**4 - 15*x**2
assert sturm_pg(p, q, x, 1)[-1] == sylvester(p, q, x, 1).det()
assert sturm_pg(p, q, x)[-1] != sylvester(p, q, x, 2).det()
assert sturm_pg(-p, q, x)[-1] == sylvester(-p, q, x, 2).det()
assert sturm_pg(-p, q, x) == modified_subresultants_pg(-p, q, x)
def test_sturm_q():
x = var('x')
p = x**3 - 7*x + 7
q = 3*x**2 - 7
assert sturm_q(p, q, x) == sturm(p)
assert sturm_q(-p, -q, x) != sturm(-p)
def test_sturm_amv():
x = var('x')
p = x**8 + x**6 - 3*x**4 - 3*x**3 + 8*x**2 + 2*x - 5
q = 3*x**6 + 5*x**4 - 4*x**2 - 9*x + 21
assert sturm_amv(p, q, x)[-1] != sylvester(p, q, x, 2).det()
sam_factors = [1, 1, -1, -1, 1, 1]
assert sturm_amv(p, q, x) == [i*j for i,j in zip(sam_factors, euclid_amv(p, q, x))]
p = -9*x**5 - 5*x**3 - 9
q = -45*x**4 - 15*x**2
assert sturm_amv(p, q, x, 1)[-1] == sylvester(p, q, x, 1).det()
assert sturm_amv(p, q, x)[-1] != sylvester(p, q, x, 2).det()
assert sturm_amv(-p, q, x)[-1] == sylvester(-p, q, x, 2).det()
assert sturm_pg(-p, q, x) == modified_subresultants_pg(-p, q, x)
def test_euclid_pg():
x = var('x')
p = x**6+x**5-x**4-x**3+x**2-x+1
q = 6*x**5+5*x**4-4*x**3-3*x**2+2*x-1
assert euclid_pg(p, q, x)[-1] == sylvester(p, q, x).det()
assert euclid_pg(p, q, x) == subresultants_pg(p, q, x)
p = x**8 + x**6 - 3*x**4 - 3*x**3 + 8*x**2 + 2*x - 5
q = 3*x**6 + 5*x**4 - 4*x**2 - 9*x + 21
assert euclid_pg(p, q, x)[-1] != sylvester(p, q, x, 2).det()
sam_factors = [1, 1, -1, -1, 1, 1]
assert euclid_pg(p, q, x) == [i*j for i,j in zip(sam_factors, sturm_pg(p, q, x))]
def test_euclid_q():
x = var('x')
p = x**3 - 7*x + 7
q = 3*x**2 - 7
assert euclid_q(p, q, x)[-1] == -sturm(p)[-1]
def test_euclid_amv():
x = var('x')
p = x**3 - 7*x + 7
q = 3*x**2 - 7
assert euclid_amv(p, q, x)[-1] == sylvester(p, q, x).det()
assert euclid_amv(p, q, x) == subresultants_amv(p, q, x)
p = x**8 + x**6 - 3*x**4 - 3*x**3 + 8*x**2 + 2*x - 5
q = 3*x**6 + 5*x**4 - 4*x**2 - 9*x + 21
assert euclid_amv(p, q, x)[-1] != sylvester(p, q, x, 2).det()
sam_factors = [1, 1, -1, -1, 1, 1]
assert euclid_amv(p, q, x) == [i*j for i,j in zip(sam_factors, sturm_amv(p, q, x))]
def test_modified_subresultants_pg():
x = var('x')
p = x**8 + x**6 - 3*x**4 - 3*x**3 + 8*x**2 + 2*x - 5
q = 3*x**6 + 5*x**4 - 4*x**2 - 9*x + 21
amv_factors = [1, 1, -1, 1, -1, 1]
assert modified_subresultants_pg(p, q, x) == [i*j for i, j in zip(amv_factors, subresultants_pg(p, q, x))]
assert modified_subresultants_pg(p, q, x)[-1] != sylvester(p + x**8, q, x).det()
assert modified_subresultants_pg(p, q, x) != sturm_pg(p, q, x)
p = x**3 - 7*x + 7
q = 3*x**2 - 7
assert modified_subresultants_pg(p, q, x) == sturm_pg(p, q, x)
assert modified_subresultants_pg(-p, q, x) != sturm_pg(-p, q, x)
def test_subresultants_pg():
x = var('x')
p = x**8 + x**6 - 3*x**4 - 3*x**3 + 8*x**2 + 2*x - 5
q = 3*x**6 + 5*x**4 - 4*x**2 - 9*x + 21
assert subresultants_pg(p, q, x) == subresultants(p, q, x)
assert subresultants_pg(p, q, x)[-1] == sylvester(p, q, x).det()
assert subresultants_pg(p, q, x) != euclid_pg(p, q, x)
amv_factors = [1, 1, -1, 1, -1, 1]
assert subresultants_pg(p, q, x) == [i*j for i, j in zip(amv_factors, modified_subresultants_amv(p, q, x))]
p = x**3 - 7*x + 7
q = 3*x**2 - 7
assert subresultants_pg(p, q, x) == euclid_pg(p, q, x)
def test_subresultants_amv_q():
x = var('x')
p = x**8 + x**6 - 3*x**4 - 3*x**3 + 8*x**2 + 2*x - 5
q = 3*x**6 + 5*x**4 - 4*x**2 - 9*x + 21
assert subresultants_amv_q(p, q, x) == subresultants(p, q, x)
assert subresultants_amv_q(p, q, x)[-1] == sylvester(p, q, x).det()
assert subresultants_amv_q(p, q, x) != euclid_amv(p, q, x)
amv_factors = [1, 1, -1, 1, -1, 1]
assert subresultants_amv_q(p, q, x) == [i*j for i, j in zip(amv_factors, modified_subresultants_amv(p, q, x))]
p = x**3 - 7*x + 7
q = 3*x**2 - 7
assert subresultants_amv(p, q, x) == euclid_amv(p, q, x)
def test_rem_z():
x = var('x')
p = x**8 + x**6 - 3*x**4 - 3*x**3 + 8*x**2 + 2*x - 5
q = 3*x**6 + 5*x**4 - 4*x**2 - 9*x + 21
assert rem_z(p, -q, x) != prem(p, -q, x)
def test_quo_z():
x = var('x')
p = x**8 + x**6 - 3*x**4 - 3*x**3 + 8*x**2 + 2*x - 5
q = 3*x**6 + 5*x**4 - 4*x**2 - 9*x + 21
assert quo_z(p, -q, x) != pquo(p, -q, x)
y = var('y')
q = 3*x**6 + 5*y**4 - 4*x**2 - 9*x + 21
assert quo_z(p, -q, x) == pquo(p, -q, x)
def test_subresultants_amv():
x = var('x')
p = x**8 + x**6 - 3*x**4 - 3*x**3 + 8*x**2 + 2*x - 5
q = 3*x**6 + 5*x**4 - 4*x**2 - 9*x + 21
assert subresultants_amv(p, q, x) == subresultants(p, q, x)
assert subresultants_amv(p, q, x)[-1] == sylvester(p, q, x).det()
assert subresultants_amv(p, q, x) != euclid_amv(p, q, x)
amv_factors = [1, 1, -1, 1, -1, 1]
assert subresultants_amv(p, q, x) == [i*j for i, j in zip(amv_factors, modified_subresultants_amv(p, q, x))]
p = x**3 - 7*x + 7
q = 3*x**2 - 7
assert subresultants_amv(p, q, x) == euclid_amv(p, q, x)
def test_modified_subresultants_amv():
x = var('x')
p = x**8 + x**6 - 3*x**4 - 3*x**3 + 8*x**2 + 2*x - 5
q = 3*x**6 + 5*x**4 - 4*x**2 - 9*x + 21
amv_factors = [1, 1, -1, 1, -1, 1]
assert modified_subresultants_amv(p, q, x) == [i*j for i, j in zip(amv_factors, subresultants_amv(p, q, x))]
assert modified_subresultants_amv(p, q, x)[-1] != sylvester(p + x**8, q, x).det()
assert modified_subresultants_amv(p, q, x) != sturm_amv(p, q, x)
p = x**3 - 7*x + 7
q = 3*x**2 - 7
assert modified_subresultants_amv(p, q, x) == sturm_amv(p, q, x)
assert modified_subresultants_amv(-p, q, x) != sturm_amv(-p, q, x)
def test_subresultants_rem():
x = var('x')
p = x**8 + x**6 - 3*x**4 - 3*x**3 + 8*x**2 + 2*x - 5
q = 3*x**6 + 5*x**4 - 4*x**2 - 9*x + 21
assert subresultants_rem(p, q, x) == subresultants(p, q, x)
assert subresultants_rem(p, q, x)[-1] == sylvester(p, q, x).det()
assert subresultants_rem(p, q, x) != euclid_amv(p, q, x)
amv_factors = [1, 1, -1, 1, -1, 1]
assert subresultants_rem(p, q, x) == [i*j for i, j in zip(amv_factors, modified_subresultants_amv(p, q, x))]
p = x**3 - 7*x + 7
q = 3*x**2 - 7
assert subresultants_rem(p, q, x) == euclid_amv(p, q, x)
def test_subresultants_vv():
x = var('x')
p = x**8 + x**6 - 3*x**4 - 3*x**3 + 8*x**2 + 2*x - 5
q = 3*x**6 + 5*x**4 - 4*x**2 - 9*x + 21
assert subresultants_vv(p, q, x) == subresultants(p, q, x)
assert subresultants_vv(p, q, x)[-1] == sylvester(p, q, x).det()
assert subresultants_vv(p, q, x) != euclid_amv(p, q, x)
amv_factors = [1, 1, -1, 1, -1, 1]
assert subresultants_vv(p, q, x) == [i*j for i, j in zip(amv_factors, modified_subresultants_amv(p, q, x))]
p = x**3 - 7*x + 7
q = 3*x**2 - 7
assert subresultants_vv(p, q, x) == euclid_amv(p, q, x)
def test_subresultants_vv_2():
x = var('x')
p = x**8 + x**6 - 3*x**4 - 3*x**3 + 8*x**2 + 2*x - 5
q = 3*x**6 + 5*x**4 - 4*x**2 - 9*x + 21
assert subresultants_vv_2(p, q, x) == subresultants(p, q, x)
assert subresultants_vv_2(p, q, x)[-1] == sylvester(p, q, x).det()
assert subresultants_vv_2(p, q, x) != euclid_amv(p, q, x)
amv_factors = [1, 1, -1, 1, -1, 1]
assert subresultants_vv_2(p, q, x) == [i*j for i, j in zip(amv_factors, modified_subresultants_amv(p, q, x))]
p = x**3 - 7*x + 7
q = 3*x**2 - 7
assert subresultants_vv_2(p, q, x) == euclid_amv(p, q, x)
|
465f8a4df2f184687ff776788065873969ae6e95556cab1814fff064284680f3
|
"""Computations with ideals of polynomial rings."""
from __future__ import print_function, division
from sympy.core.compatibility import reduce
from sympy.polys.polyerrors import CoercionFailed
class Ideal(object):
"""
Abstract base class for ideals.
Do not instantiate - use explicit constructors in the ring class instead:
>>> from sympy import QQ
>>> from sympy.abc import x
>>> QQ.old_poly_ring(x).ideal(x+1)
<x + 1>
Attributes
- ring - the ring this ideal belongs to
Non-implemented methods:
- _contains_elem
- _contains_ideal
- _quotient
- _intersect
- _union
- _product
- is_whole_ring
- is_zero
- is_prime, is_maximal, is_primary, is_radical
- is_principal
- height, depth
- radical
Methods that likely should be overridden in subclasses:
- reduce_element
"""
def _contains_elem(self, x):
"""Implementation of element containment."""
raise NotImplementedError
def _contains_ideal(self, I):
"""Implementation of ideal containment."""
raise NotImplementedError
def _quotient(self, J):
"""Implementation of ideal quotient."""
raise NotImplementedError
def _intersect(self, J):
"""Implementation of ideal intersection."""
raise NotImplementedError
def is_whole_ring(self):
"""Return True if ``self`` is the whole ring."""
raise NotImplementedError
def is_zero(self):
"""Return True if ``self`` is the zero ideal."""
raise NotImplementedError
def _equals(self, J):
"""Implementation of ideal equality."""
return self._contains_ideal(J) and J._contains_ideal(self)
def is_prime(self):
"""Return True if ``self`` is a prime ideal."""
raise NotImplementedError
def is_maximal(self):
"""Return True if ``self`` is a maximal ideal."""
raise NotImplementedError
def is_radical(self):
"""Return True if ``self`` is a radical ideal."""
raise NotImplementedError
def is_primary(self):
"""Return True if ``self`` is a primary ideal."""
raise NotImplementedError
def is_principal(self):
"""Return True if ``self`` is a principal ideal."""
raise NotImplementedError
def radical(self):
"""Compute the radical of ``self``."""
raise NotImplementedError
def depth(self):
"""Compute the depth of ``self``."""
raise NotImplementedError
def height(self):
"""Compute the height of ``self``."""
raise NotImplementedError
# TODO more
# non-implemented methods end here
def __init__(self, ring):
self.ring = ring
def _check_ideal(self, J):
"""Helper to check ``J`` is an ideal of our ring."""
if not isinstance(J, Ideal) or J.ring != self.ring:
raise ValueError(
'J must be an ideal of %s, got %s' % (self.ring, J))
def contains(self, elem):
"""
Return True if ``elem`` is an element of this ideal.
Examples
========
>>> from sympy.abc import x
>>> from sympy import QQ
>>> QQ.old_poly_ring(x).ideal(x+1, x-1).contains(3)
True
>>> QQ.old_poly_ring(x).ideal(x**2, x**3).contains(x)
False
"""
return self._contains_elem(self.ring.convert(elem))
def subset(self, other):
"""
Returns True if ``other`` is is a subset of ``self``.
Here ``other`` may be an ideal.
Examples
========
>>> from sympy.abc import x
>>> from sympy import QQ
>>> I = QQ.old_poly_ring(x).ideal(x+1)
>>> I.subset([x**2 - 1, x**2 + 2*x + 1])
True
>>> I.subset([x**2 + 1, x + 1])
False
>>> I.subset(QQ.old_poly_ring(x).ideal(x**2 - 1))
True
"""
if isinstance(other, Ideal):
return self._contains_ideal(other)
return all(self._contains_elem(x) for x in other)
def quotient(self, J, **opts):
r"""
Compute the ideal quotient of ``self`` by ``J``.
That is, if ``self`` is the ideal `I`, compute the set
`I : J = \{x \in R | xJ \subset I \}`.
Examples
========
>>> from sympy.abc import x, y
>>> from sympy import QQ
>>> R = QQ.old_poly_ring(x, y)
>>> R.ideal(x*y).quotient(R.ideal(x))
<y>
"""
self._check_ideal(J)
return self._quotient(J, **opts)
def intersect(self, J):
"""
Compute the intersection of self with ideal J.
Examples
========
>>> from sympy.abc import x, y
>>> from sympy import QQ
>>> R = QQ.old_poly_ring(x, y)
>>> R.ideal(x).intersect(R.ideal(y))
<x*y>
"""
self._check_ideal(J)
return self._intersect(J)
def saturate(self, J):
r"""
Compute the ideal saturation of ``self`` by ``J``.
That is, if ``self`` is the ideal `I`, compute the set
`I : J^\infty = \{x \in R | xJ^n \subset I \text{ for some } n\}`.
"""
raise NotImplementedError
# Note this can be implemented using repeated quotient
def union(self, J):
"""
Compute the ideal generated by the union of ``self`` and ``J``.
Examples
========
>>> from sympy.abc import x
>>> from sympy import QQ
>>> QQ.old_poly_ring(x).ideal(x**2 - 1).union(QQ.old_poly_ring(x).ideal((x+1)**2)) == QQ.old_poly_ring(x).ideal(x+1)
True
"""
self._check_ideal(J)
return self._union(J)
def product(self, J):
r"""
Compute the ideal product of ``self`` and ``J``.
That is, compute the ideal generated by products `xy`, for `x` an element
of ``self`` and `y \in J`.
Examples
========
>>> from sympy.abc import x, y
>>> from sympy import QQ
>>> QQ.old_poly_ring(x, y).ideal(x).product(QQ.old_poly_ring(x, y).ideal(y))
<x*y>
"""
self._check_ideal(J)
return self._product(J)
def reduce_element(self, x):
"""
Reduce the element ``x`` of our ring modulo the ideal ``self``.
Here "reduce" has no specific meaning: it could return a unique normal
form, simplify the expression a bit, or just do nothing.
"""
return x
def __add__(self, e):
if not isinstance(e, Ideal):
R = self.ring.quotient_ring(self)
if isinstance(e, R.dtype):
return e
if isinstance(e, R.ring.dtype):
return R(e)
return R.convert(e)
self._check_ideal(e)
return self.union(e)
__radd__ = __add__
def __mul__(self, e):
if not isinstance(e, Ideal):
try:
e = self.ring.ideal(e)
except CoercionFailed:
return NotImplemented
self._check_ideal(e)
return self.product(e)
__rmul__ = __mul__
def __pow__(self, exp):
if exp < 0:
raise NotImplementedError
# TODO exponentiate by squaring
return reduce(lambda x, y: x*y, [self]*exp, self.ring.ideal(1))
def __eq__(self, e):
if not isinstance(e, Ideal) or e.ring != self.ring:
return False
return self._equals(e)
def __ne__(self, e):
return not (self == e)
class ModuleImplementedIdeal(Ideal):
"""
Ideal implementation relying on the modules code.
Attributes:
- _module - the underlying module
"""
def __init__(self, ring, module):
Ideal.__init__(self, ring)
self._module = module
def _contains_elem(self, x):
return self._module.contains([x])
def _contains_ideal(self, J):
if not isinstance(J, ModuleImplementedIdeal):
raise NotImplementedError
return self._module.is_submodule(J._module)
def _intersect(self, J):
if not isinstance(J, ModuleImplementedIdeal):
raise NotImplementedError
return self.__class__(self.ring, self._module.intersect(J._module))
def _quotient(self, J, **opts):
if not isinstance(J, ModuleImplementedIdeal):
raise NotImplementedError
return self._module.module_quotient(J._module, **opts)
def _union(self, J):
if not isinstance(J, ModuleImplementedIdeal):
raise NotImplementedError
return self.__class__(self.ring, self._module.union(J._module))
@property
def gens(self):
"""
Return generators for ``self``.
Examples
========
>>> from sympy import QQ
>>> from sympy.abc import x, y
>>> list(QQ.old_poly_ring(x, y).ideal(x, y, x**2 + y).gens)
[x, y, x**2 + y]
"""
return (x[0] for x in self._module.gens)
def is_zero(self):
"""
Return True if ``self`` is the zero ideal.
Examples
========
>>> from sympy.abc import x
>>> from sympy import QQ
>>> QQ.old_poly_ring(x).ideal(x).is_zero()
False
>>> QQ.old_poly_ring(x).ideal().is_zero()
True
"""
return self._module.is_zero()
def is_whole_ring(self):
"""
Return True if ``self`` is the whole ring, i.e. one generator is a unit.
Examples
========
>>> from sympy.abc import x
>>> from sympy import QQ, ilex
>>> QQ.old_poly_ring(x).ideal(x).is_whole_ring()
False
>>> QQ.old_poly_ring(x).ideal(3).is_whole_ring()
True
>>> QQ.old_poly_ring(x, order=ilex).ideal(2 + x).is_whole_ring()
True
"""
return self._module.is_full_module()
def __repr__(self):
from sympy import sstr
return '<' + ','.join(sstr(x) for [x] in self._module.gens) + '>'
# NOTE this is the only method using the fact that the module is a SubModule
def _product(self, J):
if not isinstance(J, ModuleImplementedIdeal):
raise NotImplementedError
return self.__class__(self.ring, self._module.submodule(
*[[x*y] for [x] in self._module.gens for [y] in J._module.gens]))
def in_terms_of_generators(self, e):
"""
Express ``e`` in terms of the generators of ``self``.
Examples
========
>>> from sympy.abc import x
>>> from sympy import QQ
>>> I = QQ.old_poly_ring(x).ideal(x**2 + 1, x)
>>> I.in_terms_of_generators(1)
[1, -x]
"""
return self._module.in_terms_of_generators([e])
def reduce_element(self, x, **options):
return self._module.reduce_element([x], **options)[0]
|
99fa804bdc90cd0fa634a388c03280bdca5a304de57aea9e6e50773b9ee99355
|
"""
Computations with modules over polynomial rings.
This module implements various classes that encapsulate groebner basis
computations for modules. Most of them should not be instantiated by hand.
Instead, use the constructing routines on objects you already have.
For example, to construct a free module over ``QQ[x, y]``, call
``QQ[x, y].free_module(rank)`` instead of the ``FreeModule`` constructor.
In fact ``FreeModule`` is an abstract base class that should not be
instantiated, the ``free_module`` method instead returns the implementing class
``FreeModulePolyRing``.
In general, the abstract base classes implement most functionality in terms of
a few non-implemented methods. The concrete base classes supply only these
non-implemented methods. They may also supply new implementations of the
convenience methods, for example if there are faster algorithms available.
"""
from __future__ import print_function, division
from copy import copy
from sympy.core.compatibility import iterable, reduce, range
from sympy.polys.agca.ideals import Ideal
from sympy.polys.domains.field import Field
from sympy.polys.orderings import ProductOrder, monomial_key
from sympy.polys.polyerrors import CoercionFailed
# TODO
# - module saturation
# - module quotient/intersection for quotient rings
# - free resoltutions / syzygies
# - finding small/minimal generating sets
# - ...
##########################################################################
## Abstract base classes #################################################
##########################################################################
class Module(object):
"""
Abstract base class for modules.
Do not instantiate - use ring explicit constructors instead:
>>> from sympy import QQ
>>> from sympy.abc import x
>>> QQ.old_poly_ring(x).free_module(2)
QQ[x]**2
Attributes:
- dtype - type of elements
- ring - containing ring
Non-implemented methods:
- submodule
- quotient_module
- is_zero
- is_submodule
- multiply_ideal
The method convert likely needs to be changed in subclasses.
"""
def __init__(self, ring):
self.ring = ring
def convert(self, elem, M=None):
"""
Convert ``elem`` into internal representation of this module.
If ``M`` is not None, it should be a module containing it.
"""
if not isinstance(elem, self.dtype):
raise CoercionFailed
return elem
def submodule(self, *gens):
"""Generate a submodule."""
raise NotImplementedError
def quotient_module(self, other):
"""Generate a quotient module."""
raise NotImplementedError
def __div__(self, e):
if not isinstance(e, Module):
e = self.submodule(*e)
return self.quotient_module(e)
__truediv__ = __div__
def contains(self, elem):
"""Return True if ``elem`` is an element of this module."""
try:
self.convert(elem)
return True
except CoercionFailed:
return False
def __contains__(self, elem):
return self.contains(elem)
def subset(self, other):
"""
Returns True if ``other`` is is a subset of ``self``.
Examples
========
>>> from sympy.abc import x
>>> from sympy import QQ
>>> F = QQ.old_poly_ring(x).free_module(2)
>>> F.subset([(1, x), (x, 2)])
True
>>> F.subset([(1/x, x), (x, 2)])
False
"""
return all(self.contains(x) for x in other)
def __eq__(self, other):
return self.is_submodule(other) and other.is_submodule(self)
def __ne__(self, other):
return not (self == other)
def is_zero(self):
"""Returns True if ``self`` is a zero module."""
raise NotImplementedError
def is_submodule(self, other):
"""Returns True if ``other`` is a submodule of ``self``."""
raise NotImplementedError
def multiply_ideal(self, other):
"""
Multiply ``self`` by the ideal ``other``.
"""
raise NotImplementedError
def __mul__(self, e):
if not isinstance(e, Ideal):
try:
e = self.ring.ideal(e)
except (CoercionFailed, NotImplementedError):
return NotImplemented
return self.multiply_ideal(e)
__rmul__ = __mul__
def identity_hom(self):
"""Return the identity homomorphism on ``self``."""
raise NotImplementedError
class ModuleElement(object):
"""
Base class for module element wrappers.
Use this class to wrap primitive data types as module elements. It stores
a reference to the containing module, and implements all the arithmetic
operators.
Attributes:
- module - containing module
- data - internal data
Methods that likely need change in subclasses:
- add
- mul
- div
- eq
"""
def __init__(self, module, data):
self.module = module
self.data = data
def add(self, d1, d2):
"""Add data ``d1`` and ``d2``."""
return d1 + d2
def mul(self, m, d):
"""Multiply module data ``m`` by coefficient d."""
return m * d
def div(self, m, d):
"""Divide module data ``m`` by coefficient d."""
return m / d
def eq(self, d1, d2):
"""Return true if d1 and d2 represent the same element."""
return d1 == d2
def __add__(self, om):
if not isinstance(om, self.__class__) or om.module != self.module:
try:
om = self.module.convert(om)
except CoercionFailed:
return NotImplemented
return self.__class__(self.module, self.add(self.data, om.data))
__radd__ = __add__
def __neg__(self):
return self.__class__(self.module, self.mul(self.data,
self.module.ring.convert(-1)))
def __sub__(self, om):
if not isinstance(om, self.__class__) or om.module != self.module:
try:
om = self.module.convert(om)
except CoercionFailed:
return NotImplemented
return self.__add__(-om)
def __rsub__(self, om):
return (-self).__add__(om)
def __mul__(self, o):
if not isinstance(o, self.module.ring.dtype):
try:
o = self.module.ring.convert(o)
except CoercionFailed:
return NotImplemented
return self.__class__(self.module, self.mul(self.data, o))
__rmul__ = __mul__
def __div__(self, o):
if not isinstance(o, self.module.ring.dtype):
try:
o = self.module.ring.convert(o)
except CoercionFailed:
return NotImplemented
return self.__class__(self.module, self.div(self.data, o))
__truediv__ = __div__
def __eq__(self, om):
if not isinstance(om, self.__class__) or om.module != self.module:
try:
om = self.module.convert(om)
except CoercionFailed:
return False
return self.eq(self.data, om.data)
def __ne__(self, om):
return not self == om
##########################################################################
## Free Modules ##########################################################
##########################################################################
class FreeModuleElement(ModuleElement):
"""Element of a free module. Data stored as a tuple."""
def add(self, d1, d2):
return tuple(x + y for x, y in zip(d1, d2))
def mul(self, d, p):
return tuple(x * p for x in d)
def div(self, d, p):
return tuple(x / p for x in d)
def __repr__(self):
from sympy import sstr
return '[' + ', '.join(sstr(x) for x in self.data) + ']'
def __iter__(self):
return self.data.__iter__()
def __getitem__(self, idx):
return self.data[idx]
class FreeModule(Module):
"""
Abstract base class for free modules.
Additional attributes:
- rank - rank of the free module
Non-implemented methods:
- submodule
"""
dtype = FreeModuleElement
def __init__(self, ring, rank):
Module.__init__(self, ring)
self.rank = rank
def __repr__(self):
return repr(self.ring) + "**" + repr(self.rank)
def is_submodule(self, other):
"""
Returns True if ``other`` is a submodule of ``self``.
Examples
========
>>> from sympy.abc import x
>>> from sympy import QQ
>>> F = QQ.old_poly_ring(x).free_module(2)
>>> M = F.submodule([2, x])
>>> F.is_submodule(F)
True
>>> F.is_submodule(M)
True
>>> M.is_submodule(F)
False
"""
if isinstance(other, SubModule):
return other.container == self
if isinstance(other, FreeModule):
return other.ring == self.ring and other.rank == self.rank
return False
def convert(self, elem, M=None):
"""
Convert ``elem`` into the internal representation.
This method is called implicitly whenever computations involve elements
not in the internal representation.
Examples
========
>>> from sympy.abc import x
>>> from sympy import QQ
>>> F = QQ.old_poly_ring(x).free_module(2)
>>> F.convert([1, 0])
[1, 0]
"""
if isinstance(elem, FreeModuleElement):
if elem.module is self:
return elem
if elem.module.rank != self.rank:
raise CoercionFailed
return FreeModuleElement(self,
tuple(self.ring.convert(x, elem.module.ring) for x in elem.data))
elif iterable(elem):
tpl = tuple(self.ring.convert(x) for x in elem)
if len(tpl) != self.rank:
raise CoercionFailed
return FreeModuleElement(self, tpl)
elif elem is 0:
return FreeModuleElement(self, (self.ring.convert(0),)*self.rank)
else:
raise CoercionFailed
def is_zero(self):
"""
Returns True if ``self`` is a zero module.
(If, as this implementation assumes, the coefficient ring is not the
zero ring, then this is equivalent to the rank being zero.)
Examples
========
>>> from sympy.abc import x
>>> from sympy import QQ
>>> QQ.old_poly_ring(x).free_module(0).is_zero()
True
>>> QQ.old_poly_ring(x).free_module(1).is_zero()
False
"""
return self.rank == 0
def basis(self):
"""
Return a set of basis elements.
Examples
========
>>> from sympy.abc import x
>>> from sympy import QQ
>>> QQ.old_poly_ring(x).free_module(3).basis()
([1, 0, 0], [0, 1, 0], [0, 0, 1])
"""
from sympy.matrices import eye
M = eye(self.rank)
return tuple(self.convert(M.row(i)) for i in range(self.rank))
def quotient_module(self, submodule):
"""
Return a quotient module.
Examples
========
>>> from sympy.abc import x
>>> from sympy import QQ
>>> M = QQ.old_poly_ring(x).free_module(2)
>>> M.quotient_module(M.submodule([1, x], [x, 2]))
QQ[x]**2/<[1, x], [x, 2]>
Or more conicisely, using the overloaded division operator:
>>> QQ.old_poly_ring(x).free_module(2) / [[1, x], [x, 2]]
QQ[x]**2/<[1, x], [x, 2]>
"""
return QuotientModule(self.ring, self, submodule)
def multiply_ideal(self, other):
"""
Multiply ``self`` by the ideal ``other``.
Examples
========
>>> from sympy.abc import x
>>> from sympy import QQ
>>> I = QQ.old_poly_ring(x).ideal(x)
>>> F = QQ.old_poly_ring(x).free_module(2)
>>> F.multiply_ideal(I)
<[x, 0], [0, x]>
"""
return self.submodule(*self.basis()).multiply_ideal(other)
def identity_hom(self):
"""
Return the identity homomorphism on ``self``.
Examples
========
>>> from sympy.abc import x
>>> from sympy import QQ
>>> QQ.old_poly_ring(x).free_module(2).identity_hom()
Matrix([
[1, 0], : QQ[x]**2 -> QQ[x]**2
[0, 1]])
"""
from sympy.polys.agca.homomorphisms import homomorphism
return homomorphism(self, self, self.basis())
class FreeModulePolyRing(FreeModule):
"""
Free module over a generalized polynomial ring.
Do not instantiate this, use the constructor method of the ring instead:
Examples
========
>>> from sympy.abc import x
>>> from sympy import QQ
>>> F = QQ.old_poly_ring(x).free_module(3)
>>> F
QQ[x]**3
>>> F.contains([x, 1, 0])
True
>>> F.contains([1/x, 0, 1])
False
"""
def __init__(self, ring, rank):
from sympy.polys.domains.old_polynomialring import PolynomialRingBase
FreeModule.__init__(self, ring, rank)
if not isinstance(ring, PolynomialRingBase):
raise NotImplementedError('This implementation only works over '
+ 'polynomial rings, got %s' % ring)
if not isinstance(ring.dom, Field):
raise NotImplementedError('Ground domain must be a field, '
+ 'got %s' % ring.dom)
def submodule(self, *gens, **opts):
"""
Generate a submodule.
Examples
========
>>> from sympy.abc import x, y
>>> from sympy import QQ
>>> M = QQ.old_poly_ring(x, y).free_module(2).submodule([x, x + y])
>>> M
<[x, x + y]>
>>> M.contains([2*x, 2*x + 2*y])
True
>>> M.contains([x, y])
False
"""
return SubModulePolyRing(gens, self, **opts)
class FreeModuleQuotientRing(FreeModule):
"""
Free module over a quotient ring.
Do not instantiate this, use the constructor method of the ring instead:
Examples
========
>>> from sympy.abc import x
>>> from sympy import QQ
>>> F = (QQ.old_poly_ring(x)/[x**2 + 1]).free_module(3)
>>> F
(QQ[x]/<x**2 + 1>)**3
Attributes
- quot - the quotient module `R^n / IR^n`, where `R/I` is our ring
"""
def __init__(self, ring, rank):
from sympy.polys.domains.quotientring import QuotientRing
FreeModule.__init__(self, ring, rank)
if not isinstance(ring, QuotientRing):
raise NotImplementedError('This implementation only works over '
+ 'quotient rings, got %s' % ring)
F = self.ring.ring.free_module(self.rank)
self.quot = F / (self.ring.base_ideal*F)
def __repr__(self):
return "(" + repr(self.ring) + ")" + "**" + repr(self.rank)
def submodule(self, *gens, **opts):
"""
Generate a submodule.
Examples
========
>>> from sympy.abc import x, y
>>> from sympy import QQ
>>> M = (QQ.old_poly_ring(x, y)/[x**2 - y**2]).free_module(2).submodule([x, x + y])
>>> M
<[x + <x**2 - y**2>, x + y + <x**2 - y**2>]>
>>> M.contains([y**2, x**2 + x*y])
True
>>> M.contains([x, y])
False
"""
return SubModuleQuotientRing(gens, self, **opts)
def lift(self, elem):
"""
Lift the element ``elem`` of self to the module self.quot.
Note that self.quot is the same set as self, just as an R-module
and not as an R/I-module, so this makes sense.
Examples
========
>>> from sympy.abc import x
>>> from sympy import QQ
>>> F = (QQ.old_poly_ring(x)/[x**2 + 1]).free_module(2)
>>> e = F.convert([1, 0])
>>> e
[1 + <x**2 + 1>, 0 + <x**2 + 1>]
>>> L = F.quot
>>> l = F.lift(e)
>>> l
[1, 0] + <[x**2 + 1, 0], [0, x**2 + 1]>
>>> L.contains(l)
True
"""
return self.quot.convert([x.data for x in elem])
def unlift(self, elem):
"""
Push down an element of self.quot to self.
This undoes ``lift``.
Examples
========
>>> from sympy.abc import x
>>> from sympy import QQ
>>> F = (QQ.old_poly_ring(x)/[x**2 + 1]).free_module(2)
>>> e = F.convert([1, 0])
>>> l = F.lift(e)
>>> e == l
False
>>> e == F.unlift(l)
True
"""
return self.convert(elem.data)
##########################################################################
## Submodules and subquotients ###########################################
##########################################################################
class SubModule(Module):
"""
Base class for submodules.
Attributes:
- container - containing module
- gens - generators (subset of containing module)
- rank - rank of containing module
Non-implemented methods:
- _contains
- _syzygies
- _in_terms_of_generators
- _intersect
- _module_quotient
Methods that likely need change in subclasses:
- reduce_element
"""
def __init__(self, gens, container):
Module.__init__(self, container.ring)
self.gens = tuple(container.convert(x) for x in gens)
self.container = container
self.rank = container.rank
self.ring = container.ring
self.dtype = container.dtype
def __repr__(self):
return "<" + ", ".join(repr(x) for x in self.gens) + ">"
def _contains(self, other):
"""Implementation of containment.
Other is guaranteed to be FreeModuleElement."""
raise NotImplementedError
def _syzygies(self):
"""Implementation of syzygy computation wrt self generators."""
raise NotImplementedError
def _in_terms_of_generators(self, e):
"""Implementation of expression in terms of generators."""
raise NotImplementedError
def convert(self, elem, M=None):
"""
Convert ``elem`` into the internal represantition.
Mostly called implicitly.
Examples
========
>>> from sympy.abc import x
>>> from sympy import QQ
>>> M = QQ.old_poly_ring(x).free_module(2).submodule([1, x])
>>> M.convert([2, 2*x])
[2, 2*x]
"""
if isinstance(elem, self.container.dtype) and elem.module is self:
return elem
r = copy(self.container.convert(elem, M))
r.module = self
if not self._contains(r):
raise CoercionFailed
return r
def _intersect(self, other):
"""Implementation of intersection.
Other is guaranteed to be a submodule of same free module."""
raise NotImplementedError
def _module_quotient(self, other):
"""Implementation of quotient.
Other is guaranteed to be a submodule of same free module."""
raise NotImplementedError
def intersect(self, other, **options):
"""
Returns the intersection of ``self`` with submodule ``other``.
Examples
========
>>> from sympy.abc import x, y
>>> from sympy import QQ
>>> F = QQ.old_poly_ring(x, y).free_module(2)
>>> F.submodule([x, x]).intersect(F.submodule([y, y]))
<[x*y, x*y]>
Some implementation allow further options to be passed. Currently, to
only one implemented is ``relations=True``, in which case the function
will return a triple ``(res, rela, relb)``, where ``res`` is the
intersection module, and ``rela`` and ``relb`` are lists of coefficient
vectors, expressing the generators of ``res`` in terms of the
generators of ``self`` (``rela``) and ``other`` (``relb``).
>>> F.submodule([x, x]).intersect(F.submodule([y, y]), relations=True)
(<[x*y, x*y]>, [(y,)], [(x,)])
The above result says: the intersection module is generated by the
single element `(-xy, -xy) = -y (x, x) = -x (y, y)`, where
`(x, x)` and `(y, y)` respectively are the unique generators of
the two modules being intersected.
"""
if not isinstance(other, SubModule):
raise TypeError('%s is not a SubModule' % other)
if other.container != self.container:
raise ValueError(
'%s is contained in a different free module' % other)
return self._intersect(other, **options)
def module_quotient(self, other, **options):
r"""
Returns the module quotient of ``self`` by submodule ``other``.
That is, if ``self`` is the module `M` and ``other`` is `N`, then
return the ideal `\{f \in R | fN \subset M\}`.
Examples
========
>>> from sympy import QQ
>>> from sympy.abc import x, y
>>> F = QQ.old_poly_ring(x, y).free_module(2)
>>> S = F.submodule([x*y, x*y])
>>> T = F.submodule([x, x])
>>> S.module_quotient(T)
<y>
Some implementations allow further options to be passed. Currently, the
only one implemented is ``relations=True``, which may only be passed
if ``other`` is principal. In this case the function
will return a pair ``(res, rel)`` where ``res`` is the ideal, and
``rel`` is a list of coefficient vectors, expressing the generators of
the ideal, multiplied by the generator of ``other`` in terms of
generators of ``self``.
>>> S.module_quotient(T, relations=True)
(<y>, [[1]])
This means that the quotient ideal is generated by the single element
`y`, and that `y (x, x) = 1 (xy, xy)`, `(x, x)` and `(xy, xy)` being
the generators of `T` and `S`, respectively.
"""
if not isinstance(other, SubModule):
raise TypeError('%s is not a SubModule' % other)
if other.container != self.container:
raise ValueError(
'%s is contained in a different free module' % other)
return self._module_quotient(other, **options)
def union(self, other):
"""
Returns the module generated by the union of ``self`` and ``other``.
Examples
========
>>> from sympy.abc import x
>>> from sympy import QQ
>>> F = QQ.old_poly_ring(x).free_module(1)
>>> M = F.submodule([x**2 + x]) # <x(x+1)>
>>> N = F.submodule([x**2 - 1]) # <(x-1)(x+1)>
>>> M.union(N) == F.submodule([x+1])
True
"""
if not isinstance(other, SubModule):
raise TypeError('%s is not a SubModule' % other)
if other.container != self.container:
raise ValueError(
'%s is contained in a different free module' % other)
return self.__class__(self.gens + other.gens, self.container)
def is_zero(self):
"""
Return True if ``self`` is a zero module.
Examples
========
>>> from sympy.abc import x
>>> from sympy import QQ
>>> F = QQ.old_poly_ring(x).free_module(2)
>>> F.submodule([x, 1]).is_zero()
False
>>> F.submodule([0, 0]).is_zero()
True
"""
return all(x == 0 for x in self.gens)
def submodule(self, *gens):
"""
Generate a submodule.
Examples
========
>>> from sympy.abc import x
>>> from sympy import QQ
>>> M = QQ.old_poly_ring(x).free_module(2).submodule([x, 1])
>>> M.submodule([x**2, x])
<[x**2, x]>
"""
if not self.subset(gens):
raise ValueError('%s not a subset of %s' % (gens, self))
return self.__class__(gens, self.container)
def is_full_module(self):
"""
Return True if ``self`` is the entire free module.
Examples
========
>>> from sympy.abc import x
>>> from sympy import QQ
>>> F = QQ.old_poly_ring(x).free_module(2)
>>> F.submodule([x, 1]).is_full_module()
False
>>> F.submodule([1, 1], [1, 2]).is_full_module()
True
"""
return all(self.contains(x) for x in self.container.basis())
def is_submodule(self, other):
"""
Returns True if ``other`` is a submodule of ``self``.
>>> from sympy.abc import x
>>> from sympy import QQ
>>> F = QQ.old_poly_ring(x).free_module(2)
>>> M = F.submodule([2, x])
>>> N = M.submodule([2*x, x**2])
>>> M.is_submodule(M)
True
>>> M.is_submodule(N)
True
>>> N.is_submodule(M)
False
"""
if isinstance(other, SubModule):
return self.container == other.container and \
all(self.contains(x) for x in other.gens)
if isinstance(other, (FreeModule, QuotientModule)):
return self.container == other and self.is_full_module()
return False
def syzygy_module(self, **opts):
r"""
Compute the syzygy module of the generators of ``self``.
Suppose `M` is generated by `f_1, \ldots, f_n` over the ring
`R`. Consider the homomorphism `\phi: R^n \to M`, given by
sending `(r_1, \ldots, r_n) \to r_1 f_1 + \cdots + r_n f_n`.
The syzygy module is defined to be the kernel of `\phi`.
Examples
========
The syzygy module is zero iff the generators generate freely a free
submodule:
>>> from sympy.abc import x, y
>>> from sympy import QQ
>>> QQ.old_poly_ring(x).free_module(2).submodule([1, 0], [1, 1]).syzygy_module().is_zero()
True
A slightly more interesting example:
>>> M = QQ.old_poly_ring(x, y).free_module(2).submodule([x, 2*x], [y, 2*y])
>>> S = QQ.old_poly_ring(x, y).free_module(2).submodule([y, -x])
>>> M.syzygy_module() == S
True
"""
F = self.ring.free_module(len(self.gens))
# NOTE we filter out zero syzygies. This is for convenience of the
# _syzygies function and not meant to replace any real "generating set
# reduction" algorithm
return F.submodule(*[x for x in self._syzygies() if F.convert(x) != 0],
**opts)
def in_terms_of_generators(self, e):
"""
Express element ``e`` of ``self`` in terms of the generators.
Examples
========
>>> from sympy.abc import x
>>> from sympy import QQ
>>> F = QQ.old_poly_ring(x).free_module(2)
>>> M = F.submodule([1, 0], [1, 1])
>>> M.in_terms_of_generators([x, x**2])
[-x**2 + x, x**2]
"""
try:
e = self.convert(e)
except CoercionFailed:
raise ValueError('%s is not an element of %s' % (e, self))
return self._in_terms_of_generators(e)
def reduce_element(self, x):
"""
Reduce the element ``x`` of our ring modulo the ideal ``self``.
Here "reduce" has no specific meaning, it could return a unique normal
form, simplify the expression a bit, or just do nothing.
"""
return x
def quotient_module(self, other, **opts):
"""
Return a quotient module.
This is the same as taking a submodule of a quotient of the containing
module.
Examples
========
>>> from sympy.abc import x
>>> from sympy import QQ
>>> F = QQ.old_poly_ring(x).free_module(2)
>>> S1 = F.submodule([x, 1])
>>> S2 = F.submodule([x**2, x])
>>> S1.quotient_module(S2)
<[x, 1] + <[x**2, x]>>
Or more coincisely, using the overloaded division operator:
>>> F.submodule([x, 1]) / [(x**2, x)]
<[x, 1] + <[x**2, x]>>
"""
if not self.is_submodule(other):
raise ValueError('%s not a submodule of %s' % (other, self))
return SubQuotientModule(self.gens,
self.container.quotient_module(other), **opts)
def __add__(self, oth):
return self.container.quotient_module(self).convert(oth)
__radd__ = __add__
def multiply_ideal(self, I):
"""
Multiply ``self`` by the ideal ``I``.
Examples
========
>>> from sympy.abc import x
>>> from sympy import QQ
>>> I = QQ.old_poly_ring(x).ideal(x**2)
>>> M = QQ.old_poly_ring(x).free_module(2).submodule([1, 1])
>>> I*M
<[x**2, x**2]>
"""
return self.submodule(*[x*g for [x] in I._module.gens for g in self.gens])
def inclusion_hom(self):
"""
Return a homomorphism representing the inclusion map of ``self``.
That is, the natural map from ``self`` to ``self.container``.
Examples
========
>>> from sympy.abc import x
>>> from sympy import QQ
>>> QQ.old_poly_ring(x).free_module(2).submodule([x, x]).inclusion_hom()
Matrix([
[1, 0], : <[x, x]> -> QQ[x]**2
[0, 1]])
"""
return self.container.identity_hom().restrict_domain(self)
def identity_hom(self):
"""
Return the identity homomorphism on ``self``.
Examples
========
>>> from sympy.abc import x
>>> from sympy import QQ
>>> QQ.old_poly_ring(x).free_module(2).submodule([x, x]).identity_hom()
Matrix([
[1, 0], : <[x, x]> -> <[x, x]>
[0, 1]])
"""
return self.container.identity_hom().restrict_domain(
self).restrict_codomain(self)
class SubQuotientModule(SubModule):
"""
Submodule of a quotient module.
Equivalently, quotient module of a submodule.
Do not instantiate this, instead use the submodule or quotient_module
constructing methods:
>>> from sympy.abc import x
>>> from sympy import QQ
>>> F = QQ.old_poly_ring(x).free_module(2)
>>> S = F.submodule([1, 0], [1, x])
>>> Q = F/[(1, 0)]
>>> S/[(1, 0)] == Q.submodule([5, x])
True
Attributes:
- base - base module we are quotient of
- killed_module - submodule used to form the quotient
"""
def __init__(self, gens, container, **opts):
SubModule.__init__(self, gens, container)
self.killed_module = self.container.killed_module
# XXX it is important for some code below that the generators of base
# are in this particular order!
self.base = self.container.base.submodule(
*[x.data for x in self.gens], **opts).union(self.killed_module)
def _contains(self, elem):
return self.base.contains(elem.data)
def _syzygies(self):
# let N = self.killed_module be generated by e_1, ..., e_r
# let F = self.base be generated by f_1, ..., f_s and e_1, ..., e_r
# Then self = F/N.
# Let phi: R**s --> self be the evident surjection.
# Similarly psi: R**(s + r) --> F.
# We need to find generators for ker(phi). Let chi: R**s --> F be the
# evident lift of phi. For X in R**s, phi(X) = 0 iff chi(X) is
# contained in N, iff there exists Y in R**r such that
# psi(X, Y) = 0.
# Hence if alpha: R**(s + r) --> R**s is the projection map, then
# ker(phi) = alpha ker(psi).
return [X[:len(self.gens)] for X in self.base._syzygies()]
def _in_terms_of_generators(self, e):
return self.base._in_terms_of_generators(e.data)[:len(self.gens)]
def is_full_module(self):
"""
Return True if ``self`` is the entire free module.
Examples
========
>>> from sympy.abc import x
>>> from sympy import QQ
>>> F = QQ.old_poly_ring(x).free_module(2)
>>> F.submodule([x, 1]).is_full_module()
False
>>> F.submodule([1, 1], [1, 2]).is_full_module()
True
"""
return self.base.is_full_module()
def quotient_hom(self):
"""
Return the quotient homomorphism to self.
That is, return the natural map from ``self.base`` to ``self``.
Examples
========
>>> from sympy.abc import x
>>> from sympy import QQ
>>> M = (QQ.old_poly_ring(x).free_module(2) / [(1, x)]).submodule([1, 0])
>>> M.quotient_hom()
Matrix([
[1, 0], : <[1, 0], [1, x]> -> <[1, 0] + <[1, x]>, [1, x] + <[1, x]>>
[0, 1]])
"""
return self.base.identity_hom().quotient_codomain(self.killed_module)
_subs0 = lambda x: x[0]
_subs1 = lambda x: x[1:]
class ModuleOrder(ProductOrder):
"""A product monomial order with a zeroth term as module index."""
def __init__(self, o1, o2, TOP):
if TOP:
ProductOrder.__init__(self, (o2, _subs1), (o1, _subs0))
else:
ProductOrder.__init__(self, (o1, _subs0), (o2, _subs1))
class SubModulePolyRing(SubModule):
"""
Submodule of a free module over a generalized polynomial ring.
Do not instantiate this, use the constructor method of FreeModule instead:
>>> from sympy.abc import x, y
>>> from sympy import QQ
>>> F = QQ.old_poly_ring(x, y).free_module(2)
>>> F.submodule([x, y], [1, 0])
<[x, y], [1, 0]>
Attributes:
- order - monomial order used
"""
#self._gb - cached groebner basis
#self._gbe - cached groebner basis relations
def __init__(self, gens, container, order="lex", TOP=True):
SubModule.__init__(self, gens, container)
if not isinstance(container, FreeModulePolyRing):
raise NotImplementedError('This implementation is for submodules of '
+ 'FreeModulePolyRing, got %s' % container)
self.order = ModuleOrder(monomial_key(order), self.ring.order, TOP)
self._gb = None
self._gbe = None
def __eq__(self, other):
if isinstance(other, SubModulePolyRing) and self.order != other.order:
return False
return SubModule.__eq__(self, other)
def _groebner(self, extended=False):
"""Returns a standard basis in sdm form."""
from sympy.polys.distributedmodules import sdm_groebner, sdm_nf_mora
if self._gbe is None and extended:
gb, gbe = sdm_groebner(
[self.ring._vector_to_sdm(x, self.order) for x in self.gens],
sdm_nf_mora, self.order, self.ring.dom, extended=True)
self._gb, self._gbe = tuple(gb), tuple(gbe)
if self._gb is None:
self._gb = tuple(sdm_groebner(
[self.ring._vector_to_sdm(x, self.order) for x in self.gens],
sdm_nf_mora, self.order, self.ring.dom))
if extended:
return self._gb, self._gbe
else:
return self._gb
def _groebner_vec(self, extended=False):
"""Returns a standard basis in element form."""
if not extended:
return [self.convert(self.ring._sdm_to_vector(x, self.rank))
for x in self._groebner()]
gb, gbe = self._groebner(extended=True)
return ([self.convert(self.ring._sdm_to_vector(x, self.rank))
for x in gb],
[self.ring._sdm_to_vector(x, len(self.gens)) for x in gbe])
def _contains(self, x):
from sympy.polys.distributedmodules import sdm_zero, sdm_nf_mora
return sdm_nf_mora(self.ring._vector_to_sdm(x, self.order),
self._groebner(), self.order, self.ring.dom) == \
sdm_zero()
def _syzygies(self):
"""Compute syzygies. See [SCA, algorithm 2.5.4]."""
# NOTE if self.gens is a standard basis, this can be done more
# efficiently using Schreyer's theorem
from sympy.matrices import eye
# First bullet point
k = len(self.gens)
r = self.rank
im = eye(k)
Rkr = self.ring.free_module(r + k)
newgens = []
for j, f in enumerate(self.gens):
m = [0]*(r + k)
for i, v in enumerate(f):
m[i] = f[i]
for i in range(k):
m[r + i] = im[j, i]
newgens.append(Rkr.convert(m))
# Note: we need *descending* order on module index, and TOP=False to
# get an elimination order
F = Rkr.submodule(*newgens, order='ilex', TOP=False)
# Second bullet point: standard basis of F
G = F._groebner_vec()
# Third bullet point: G0 = G intersect the new k components
G0 = [x[r:] for x in G if all(y == self.ring.convert(0)
for y in x[:r])]
# Fourth and fifth bullet points: we are done
return G0
def _in_terms_of_generators(self, e):
"""Expression in terms of generators. See [SCA, 2.8.1]."""
# NOTE: if gens is a standard basis, this can be done more efficiently
M = self.ring.free_module(self.rank).submodule(*((e,) + self.gens))
S = M.syzygy_module(
order="ilex", TOP=False) # We want decreasing order!
G = S._groebner_vec()
# This list cannot not be empty since e is an element
e = [x for x in G if self.ring.is_unit(x[0])][0]
return [-x/e[0] for x in e[1:]]
def reduce_element(self, x, NF=None):
"""
Reduce the element ``x`` of our container modulo ``self``.
This applies the normal form ``NF`` to ``x``. If ``NF`` is passed
as none, the default Mora normal form is used (which is not unique!).
"""
from sympy.polys.distributedmodules import sdm_nf_mora
if NF is None:
NF = sdm_nf_mora
return self.container.convert(self.ring._sdm_to_vector(NF(
self.ring._vector_to_sdm(x, self.order), self._groebner(),
self.order, self.ring.dom),
self.rank))
def _intersect(self, other, relations=False):
# See: [SCA, section 2.8.2]
fi = self.gens
hi = other.gens
r = self.rank
ci = [[0]*(2*r) for _ in range(r)]
for k in range(r):
ci[k][k] = 1
ci[k][r + k] = 1
di = [list(f) + [0]*r for f in fi]
ei = [[0]*r + list(h) for h in hi]
syz = self.ring.free_module(2*r).submodule(*(ci + di + ei))._syzygies()
nonzero = [x for x in syz if any(y != self.ring.zero for y in x[:r])]
res = self.container.submodule(*([-y for y in x[:r]] for x in nonzero))
reln1 = [x[r:r + len(fi)] for x in nonzero]
reln2 = [x[r + len(fi):] for x in nonzero]
if relations:
return res, reln1, reln2
return res
def _module_quotient(self, other, relations=False):
# See: [SCA, section 2.8.4]
if relations and len(other.gens) != 1:
raise NotImplementedError
if len(other.gens) == 0:
return self.ring.ideal(1)
elif len(other.gens) == 1:
# We do some trickery. Let f be the (vector!) generating ``other``
# and f1, .., fn be the (vectors) generating self.
# Consider the submodule of R^{r+1} generated by (f, 1) and
# {(fi, 0) | i}. Then the intersection with the last module
# component yields the quotient.
g1 = list(other.gens[0]) + [1]
gi = [list(x) + [0] for x in self.gens]
# NOTE: We *need* to use an elimination order
M = self.ring.free_module(self.rank + 1).submodule(*([g1] + gi),
order='ilex', TOP=False)
if not relations:
return self.ring.ideal(*[x[-1] for x in M._groebner_vec() if
all(y == self.ring.zero for y in x[:-1])])
else:
G, R = M._groebner_vec(extended=True)
indices = [i for i, x in enumerate(G) if
all(y == self.ring.zero for y in x[:-1])]
return (self.ring.ideal(*[G[i][-1] for i in indices]),
[[-x for x in R[i][1:]] for i in indices])
# For more generators, we use I : <h1, .., hn> = intersection of
# {I : <hi> | i}
# TODO this can be done more efficiently
return reduce(lambda x, y: x.intersect(y),
(self._module_quotient(self.container.submodule(x)) for x in other.gens))
class SubModuleQuotientRing(SubModule):
"""
Class for submodules of free modules over quotient rings.
Do not instantiate this. Instead use the submodule methods.
>>> from sympy.abc import x, y
>>> from sympy import QQ
>>> M = (QQ.old_poly_ring(x, y)/[x**2 - y**2]).free_module(2).submodule([x, x + y])
>>> M
<[x + <x**2 - y**2>, x + y + <x**2 - y**2>]>
>>> M.contains([y**2, x**2 + x*y])
True
>>> M.contains([x, y])
False
Attributes:
- quot - the subquotient of `R^n/IR^n` generated by lifts of our generators
"""
def __init__(self, gens, container):
SubModule.__init__(self, gens, container)
self.quot = self.container.quot.submodule(
*[self.container.lift(x) for x in self.gens])
def _contains(self, elem):
return self.quot._contains(self.container.lift(elem))
def _syzygies(self):
return [tuple(self.ring.convert(y, self.quot.ring) for y in x)
for x in self.quot._syzygies()]
def _in_terms_of_generators(self, elem):
return [self.ring.convert(x, self.quot.ring) for x in
self.quot._in_terms_of_generators(self.container.lift(elem))]
##########################################################################
## Quotient Modules ######################################################
##########################################################################
class QuotientModuleElement(ModuleElement):
"""Element of a quotient module."""
def eq(self, d1, d2):
"""Equality comparison."""
return self.module.killed_module.contains(d1 - d2)
def __repr__(self):
return repr(self.data) + " + " + repr(self.module.killed_module)
class QuotientModule(Module):
"""
Class for quotient modules.
Do not instantiate this directly. For subquotients, see the
SubQuotientModule class.
Attributes:
- base - the base module we are a quotient of
- killed_module - the submodule used to form the quotient
- rank of the base
"""
dtype = QuotientModuleElement
def __init__(self, ring, base, submodule):
Module.__init__(self, ring)
if not base.is_submodule(submodule):
raise ValueError('%s is not a submodule of %s' % (submodule, base))
self.base = base
self.killed_module = submodule
self.rank = base.rank
def __repr__(self):
return repr(self.base) + "/" + repr(self.killed_module)
def is_zero(self):
"""
Return True if ``self`` is a zero module.
This happens if and only if the base module is the same as the
submodule being killed.
Examples
========
>>> from sympy.abc import x
>>> from sympy import QQ
>>> F = QQ.old_poly_ring(x).free_module(2)
>>> (F/[(1, 0)]).is_zero()
False
>>> (F/[(1, 0), (0, 1)]).is_zero()
True
"""
return self.base == self.killed_module
def is_submodule(self, other):
"""
Return True if ``other`` is a submodule of ``self``.
Examples
========
>>> from sympy.abc import x
>>> from sympy import QQ
>>> Q = QQ.old_poly_ring(x).free_module(2) / [(x, x)]
>>> S = Q.submodule([1, 0])
>>> Q.is_submodule(S)
True
>>> S.is_submodule(Q)
False
"""
if isinstance(other, QuotientModule):
return self.killed_module == other.killed_module and \
self.base.is_submodule(other.base)
if isinstance(other, SubQuotientModule):
return other.container == self
return False
def submodule(self, *gens, **opts):
"""
Generate a submodule.
This is the same as taking a quotient of a submodule of the base
module.
Examples
========
>>> from sympy.abc import x
>>> from sympy import QQ
>>> Q = QQ.old_poly_ring(x).free_module(2) / [(x, x)]
>>> Q.submodule([x, 0])
<[x, 0] + <[x, x]>>
"""
return SubQuotientModule(gens, self, **opts)
def convert(self, elem, M=None):
"""
Convert ``elem`` into the internal representation.
This method is called implicitly whenever computations involve elements
not in the internal representation.
Examples
========
>>> from sympy.abc import x
>>> from sympy import QQ
>>> F = QQ.old_poly_ring(x).free_module(2) / [(1, 2), (1, x)]
>>> F.convert([1, 0])
[1, 0] + <[1, 2], [1, x]>
"""
if isinstance(elem, QuotientModuleElement):
if elem.module is self:
return elem
if self.killed_module.is_submodule(elem.module.killed_module):
return QuotientModuleElement(self, self.base.convert(elem.data))
raise CoercionFailed
return QuotientModuleElement(self, self.base.convert(elem))
def identity_hom(self):
"""
Return the identity homomorphism on ``self``.
Examples
========
>>> from sympy.abc import x
>>> from sympy import QQ
>>> M = QQ.old_poly_ring(x).free_module(2) / [(1, 2), (1, x)]
>>> M.identity_hom()
Matrix([
[1, 0], : QQ[x]**2/<[1, 2], [1, x]> -> QQ[x]**2/<[1, 2], [1, x]>
[0, 1]])
"""
return self.base.identity_hom().quotient_codomain(
self.killed_module).quotient_domain(self.killed_module)
def quotient_hom(self):
"""
Return the quotient homomorphism to ``self``.
That is, return a homomorphism representing the natural map from
``self.base`` to ``self``.
Examples
========
>>> from sympy.abc import x
>>> from sympy import QQ
>>> M = QQ.old_poly_ring(x).free_module(2) / [(1, 2), (1, x)]
>>> M.quotient_hom()
Matrix([
[1, 0], : QQ[x]**2 -> QQ[x]**2/<[1, 2], [1, x]>
[0, 1]])
"""
return self.base.identity_hom().quotient_codomain(
self.killed_module)
|
1b8440056cc6c94701391b072b9df3d4fe3b46726b7b7ec2983384debdf77490
|
"""
Computations with homomorphisms of modules and rings.
This module implements classes for representing homomorphisms of rings and
their modules. Instead of instantiating the classes directly, you should use
the function ``homomorphism(from, to, matrix)`` to create homomorphism objects.
"""
from __future__ import print_function, division
from sympy.core.compatibility import range
from sympy.polys.agca.modules import (Module, FreeModule, QuotientModule,
SubModule, SubQuotientModule)
from sympy.polys.polyerrors import CoercionFailed
# The main computational task for module homomorphisms is kernels.
# For this reason, the concrete classes are organised by domain module type.
class ModuleHomomorphism(object):
"""
Abstract base class for module homomoprhisms. Do not instantiate.
Instead, use the ``homomorphism`` function:
>>> from sympy import QQ
>>> from sympy.abc import x
>>> from sympy.polys.agca import homomorphism
>>> F = QQ.old_poly_ring(x).free_module(2)
>>> homomorphism(F, F, [[1, 0], [0, 1]])
Matrix([
[1, 0], : QQ[x]**2 -> QQ[x]**2
[0, 1]])
Attributes:
- ring - the ring over which we are considering modules
- domain - the domain module
- codomain - the codomain module
- _ker - cached kernel
- _img - cached image
Non-implemented methods:
- _kernel
- _image
- _restrict_domain
- _restrict_codomain
- _quotient_domain
- _quotient_codomain
- _apply
- _mul_scalar
- _compose
- _add
"""
def __init__(self, domain, codomain):
if not isinstance(domain, Module):
raise TypeError('Source must be a module, got %s' % domain)
if not isinstance(codomain, Module):
raise TypeError('Target must be a module, got %s' % codomain)
if domain.ring != codomain.ring:
raise ValueError('Source and codomain must be over same ring, '
'got %s != %s' % (domain, codomain))
self.domain = domain
self.codomain = codomain
self.ring = domain.ring
self._ker = None
self._img = None
def kernel(self):
r"""
Compute the kernel of ``self``.
That is, if ``self`` is the homomorphism `\phi: M \to N`, then compute
`ker(\phi) = \{x \in M | \phi(x) = 0\}`. This is a submodule of `M`.
Examples
========
>>> from sympy import QQ
>>> from sympy.abc import x
>>> from sympy.polys.agca import homomorphism
>>> F = QQ.old_poly_ring(x).free_module(2)
>>> homomorphism(F, F, [[1, 0], [x, 0]]).kernel()
<[x, -1]>
"""
if self._ker is None:
self._ker = self._kernel()
return self._ker
def image(self):
r"""
Compute the image of ``self``.
That is, if ``self`` is the homomorphism `\phi: M \to N`, then compute
`im(\phi) = \{\phi(x) | x \in M \}`. This is a submodule of `N`.
Examples
========
>>> from sympy import QQ
>>> from sympy.abc import x
>>> from sympy.polys.agca import homomorphism
>>> F = QQ.old_poly_ring(x).free_module(2)
>>> homomorphism(F, F, [[1, 0], [x, 0]]).image() == F.submodule([1, 0])
True
"""
if self._img is None:
self._img = self._image()
return self._img
def _kernel(self):
"""Compute the kernel of ``self``."""
raise NotImplementedError
def _image(self):
"""Compute the image of ``self``."""
raise NotImplementedError
def _restrict_domain(self, sm):
"""Implementation of domain restriction."""
raise NotImplementedError
def _restrict_codomain(self, sm):
"""Implementation of codomain restriction."""
raise NotImplementedError
def _quotient_domain(self, sm):
"""Implementation of domain quotient."""
raise NotImplementedError
def _quotient_codomain(self, sm):
"""Implementation of codomain quotient."""
raise NotImplementedError
def restrict_domain(self, sm):
"""
Return ``self``, with the domain restricted to ``sm``.
Here ``sm`` has to be a submodule of ``self.domain``.
Examples
========
>>> from sympy import QQ
>>> from sympy.abc import x
>>> from sympy.polys.agca import homomorphism
>>> F = QQ.old_poly_ring(x).free_module(2)
>>> h = homomorphism(F, F, [[1, 0], [x, 0]])
>>> h
Matrix([
[1, x], : QQ[x]**2 -> QQ[x]**2
[0, 0]])
>>> h.restrict_domain(F.submodule([1, 0]))
Matrix([
[1, x], : <[1, 0]> -> QQ[x]**2
[0, 0]])
This is the same as just composing on the right with the submodule
inclusion:
>>> h * F.submodule([1, 0]).inclusion_hom()
Matrix([
[1, x], : <[1, 0]> -> QQ[x]**2
[0, 0]])
"""
if not self.domain.is_submodule(sm):
raise ValueError('sm must be a submodule of %s, got %s'
% (self.domain, sm))
if sm == self.domain:
return self
return self._restrict_domain(sm)
def restrict_codomain(self, sm):
"""
Return ``self``, with codomain restricted to to ``sm``.
Here ``sm`` has to be a submodule of ``self.codomain`` containing the
image.
Examples
========
>>> from sympy import QQ
>>> from sympy.abc import x
>>> from sympy.polys.agca import homomorphism
>>> F = QQ.old_poly_ring(x).free_module(2)
>>> h = homomorphism(F, F, [[1, 0], [x, 0]])
>>> h
Matrix([
[1, x], : QQ[x]**2 -> QQ[x]**2
[0, 0]])
>>> h.restrict_codomain(F.submodule([1, 0]))
Matrix([
[1, x], : QQ[x]**2 -> <[1, 0]>
[0, 0]])
"""
if not sm.is_submodule(self.image()):
raise ValueError('the image %s must contain sm, got %s'
% (self.image(), sm))
if sm == self.codomain:
return self
return self._restrict_codomain(sm)
def quotient_domain(self, sm):
"""
Return ``self`` with domain replaced by ``domain/sm``.
Here ``sm`` must be a submodule of ``self.kernel()``.
Examples
========
>>> from sympy import QQ
>>> from sympy.abc import x
>>> from sympy.polys.agca import homomorphism
>>> F = QQ.old_poly_ring(x).free_module(2)
>>> h = homomorphism(F, F, [[1, 0], [x, 0]])
>>> h
Matrix([
[1, x], : QQ[x]**2 -> QQ[x]**2
[0, 0]])
>>> h.quotient_domain(F.submodule([-x, 1]))
Matrix([
[1, x], : QQ[x]**2/<[-x, 1]> -> QQ[x]**2
[0, 0]])
"""
if not self.kernel().is_submodule(sm):
raise ValueError('kernel %s must contain sm, got %s' %
(self.kernel(), sm))
if sm.is_zero():
return self
return self._quotient_domain(sm)
def quotient_codomain(self, sm):
"""
Return ``self`` with codomain replaced by ``codomain/sm``.
Here ``sm`` must be a submodule of ``self.codomain``.
Examples
========
>>> from sympy import QQ
>>> from sympy.abc import x
>>> from sympy.polys.agca import homomorphism
>>> F = QQ.old_poly_ring(x).free_module(2)
>>> h = homomorphism(F, F, [[1, 0], [x, 0]])
>>> h
Matrix([
[1, x], : QQ[x]**2 -> QQ[x]**2
[0, 0]])
>>> h.quotient_codomain(F.submodule([1, 1]))
Matrix([
[1, x], : QQ[x]**2 -> QQ[x]**2/<[1, 1]>
[0, 0]])
This is the same as composing with the quotient map on the left:
>>> (F/[(1, 1)]).quotient_hom() * h
Matrix([
[1, x], : QQ[x]**2 -> QQ[x]**2/<[1, 1]>
[0, 0]])
"""
if not self.codomain.is_submodule(sm):
raise ValueError('sm must be a submodule of codomain %s, got %s'
% (self.codomain, sm))
if sm.is_zero():
return self
return self._quotient_codomain(sm)
def _apply(self, elem):
"""Apply ``self`` to ``elem``."""
raise NotImplementedError
def __call__(self, elem):
return self.codomain.convert(self._apply(self.domain.convert(elem)))
def _compose(self, oth):
"""
Compose ``self`` with ``oth``, that is, return the homomorphism
obtained by first applying then ``self``, then ``oth``.
(This method is private since in this syntax, it is non-obvious which
homomorphism is executed first.)
"""
raise NotImplementedError
def _mul_scalar(self, c):
"""Scalar multiplication. ``c`` is guaranteed in self.ring."""
raise NotImplementedError
def _add(self, oth):
"""
Homomorphism addition.
``oth`` is guaranteed to be a homomorphism with same domain/codomain.
"""
raise NotImplementedError
def _check_hom(self, oth):
"""Helper to check that oth is a homomorphism with same domain/codomain."""
if not isinstance(oth, ModuleHomomorphism):
return False
return oth.domain == self.domain and oth.codomain == self.codomain
def __mul__(self, oth):
if isinstance(oth, ModuleHomomorphism) and self.domain == oth.codomain:
return oth._compose(self)
try:
return self._mul_scalar(self.ring.convert(oth))
except CoercionFailed:
return NotImplemented
# NOTE: _compose will never be called from rmul
__rmul__ = __mul__
def __div__(self, oth):
try:
return self._mul_scalar(1/self.ring.convert(oth))
except CoercionFailed:
return NotImplemented
__truediv__ = __div__
def __add__(self, oth):
if self._check_hom(oth):
return self._add(oth)
return NotImplemented
def __sub__(self, oth):
if self._check_hom(oth):
return self._add(oth._mul_scalar(self.ring.convert(-1)))
return NotImplemented
def is_injective(self):
"""
Return True if ``self`` is injective.
That is, check if the elements of the domain are mapped to the same
codomain element.
Examples
========
>>> from sympy import QQ
>>> from sympy.abc import x
>>> from sympy.polys.agca import homomorphism
>>> F = QQ.old_poly_ring(x).free_module(2)
>>> h = homomorphism(F, F, [[1, 0], [x, 0]])
>>> h.is_injective()
False
>>> h.quotient_domain(h.kernel()).is_injective()
True
"""
return self.kernel().is_zero()
def is_surjective(self):
"""
Return True if ``self`` is surjective.
That is, check if every element of the codomain has at least one
preimage.
Examples
========
>>> from sympy import QQ
>>> from sympy.abc import x
>>> from sympy.polys.agca import homomorphism
>>> F = QQ.old_poly_ring(x).free_module(2)
>>> h = homomorphism(F, F, [[1, 0], [x, 0]])
>>> h.is_surjective()
False
>>> h.restrict_codomain(h.image()).is_surjective()
True
"""
return self.image() == self.codomain
def is_isomorphism(self):
"""
Return True if ``self`` is an isomorphism.
That is, check if every element of the codomain has precisely one
preimage. Equivalently, ``self`` is both injective and surjective.
Examples
========
>>> from sympy import QQ
>>> from sympy.abc import x
>>> from sympy.polys.agca import homomorphism
>>> F = QQ.old_poly_ring(x).free_module(2)
>>> h = homomorphism(F, F, [[1, 0], [x, 0]])
>>> h = h.restrict_codomain(h.image())
>>> h.is_isomorphism()
False
>>> h.quotient_domain(h.kernel()).is_isomorphism()
True
"""
return self.is_injective() and self.is_surjective()
def is_zero(self):
"""
Return True if ``self`` is a zero morphism.
That is, check if every element of the domain is mapped to zero
under self.
Examples
========
>>> from sympy import QQ
>>> from sympy.abc import x
>>> from sympy.polys.agca import homomorphism
>>> F = QQ.old_poly_ring(x).free_module(2)
>>> h = homomorphism(F, F, [[1, 0], [x, 0]])
>>> h.is_zero()
False
>>> h.restrict_domain(F.submodule()).is_zero()
True
>>> h.quotient_codomain(h.image()).is_zero()
True
"""
return self.image().is_zero()
def __eq__(self, oth):
try:
return (self - oth).is_zero()
except TypeError:
return False
def __ne__(self, oth):
return not (self == oth)
class MatrixHomomorphism(ModuleHomomorphism):
r"""
Helper class for all homomoprhisms which are expressed via a matrix.
That is, for such homomorphisms ``domain`` is contained in a module
generated by finitely many elements `e_1, \ldots, e_n`, so that the
homomorphism is determined uniquely by its action on the `e_i`. It
can thus be represented as a vector of elements of the codomain module,
or potentially a supermodule of the codomain module
(and hence conventionally as a matrix, if there is a similar interpretation
for elements of the codomain module).
Note that this class does *not* assume that the `e_i` freely generate a
submodule, nor that ``domain`` is even all of this submodule. It exists
only to unify the interface.
Do not instantiate.
Attributes:
- matrix - the list of images determining the homomorphism.
NOTE: the elements of matrix belong to either self.codomain or
self.codomain.container
Still non-implemented methods:
- kernel
- _apply
"""
def __init__(self, domain, codomain, matrix):
ModuleHomomorphism.__init__(self, domain, codomain)
if len(matrix) != domain.rank:
raise ValueError('Need to provide %s elements, got %s'
% (domain.rank, len(matrix)))
converter = self.codomain.convert
if isinstance(self.codomain, (SubModule, SubQuotientModule)):
converter = self.codomain.container.convert
self.matrix = tuple(converter(x) for x in matrix)
def _sympy_matrix(self):
"""Helper function which returns a sympy matrix ``self.matrix``."""
from sympy.matrices import Matrix
c = lambda x: x
if isinstance(self.codomain, (QuotientModule, SubQuotientModule)):
c = lambda x: x.data
return Matrix([[self.ring.to_sympy(y) for y in c(x)] for x in self.matrix]).T
def __repr__(self):
lines = repr(self._sympy_matrix()).split('\n')
t = " : %s -> %s" % (self.domain, self.codomain)
s = ' '*len(t)
n = len(lines)
for i in range(n // 2):
lines[i] += s
lines[n // 2] += t
for i in range(n//2 + 1, n):
lines[i] += s
return '\n'.join(lines)
def _restrict_domain(self, sm):
"""Implementation of domain restriction."""
return SubModuleHomomorphism(sm, self.codomain, self.matrix)
def _restrict_codomain(self, sm):
"""Implementation of codomain restriction."""
return self.__class__(self.domain, sm, self.matrix)
def _quotient_domain(self, sm):
"""Implementation of domain quotient."""
return self.__class__(self.domain/sm, self.codomain, self.matrix)
def _quotient_codomain(self, sm):
"""Implementation of codomain quotient."""
Q = self.codomain/sm
converter = Q.convert
if isinstance(self.codomain, SubModule):
converter = Q.container.convert
return self.__class__(self.domain, self.codomain/sm,
[converter(x) for x in self.matrix])
def _add(self, oth):
return self.__class__(self.domain, self.codomain,
[x + y for x, y in zip(self.matrix, oth.matrix)])
def _mul_scalar(self, c):
return self.__class__(self.domain, self.codomain, [c*x for x in self.matrix])
def _compose(self, oth):
return self.__class__(self.domain, oth.codomain, [oth(x) for x in self.matrix])
class FreeModuleHomomorphism(MatrixHomomorphism):
"""
Concrete class for homomorphisms with domain a free module or a quotient
thereof.
Do not instantiate; the constructor does not check that your data is well
defined. Use the ``homomorphism`` function instead:
>>> from sympy import QQ
>>> from sympy.abc import x
>>> from sympy.polys.agca import homomorphism
>>> F = QQ.old_poly_ring(x).free_module(2)
>>> homomorphism(F, F, [[1, 0], [0, 1]])
Matrix([
[1, 0], : QQ[x]**2 -> QQ[x]**2
[0, 1]])
"""
def _apply(self, elem):
if isinstance(self.domain, QuotientModule):
elem = elem.data
return sum(x * e for x, e in zip(elem, self.matrix))
def _image(self):
return self.codomain.submodule(*self.matrix)
def _kernel(self):
# The domain is either a free module or a quotient thereof.
# It does not matter if it is a quotient, because that won't increase
# the kernel.
# Our generators {e_i} are sent to the matrix entries {b_i}.
# The kernel is essentially the syzygy module of these {b_i}.
syz = self.image().syzygy_module()
return self.domain.submodule(*syz.gens)
class SubModuleHomomorphism(MatrixHomomorphism):
"""
Concrete class for homomorphism with domain a submodule of a free module
or a quotient thereof.
Do not instantiate; the constructor does not check that your data is well
defined. Use the ``homomorphism`` function instead:
>>> from sympy import QQ
>>> from sympy.abc import x
>>> from sympy.polys.agca import homomorphism
>>> M = QQ.old_poly_ring(x).free_module(2)*x
>>> homomorphism(M, M, [[1, 0], [0, 1]])
Matrix([
[1, 0], : <[x, 0], [0, x]> -> <[x, 0], [0, x]>
[0, 1]])
"""
def _apply(self, elem):
if isinstance(self.domain, SubQuotientModule):
elem = elem.data
return sum(x * e for x, e in zip(elem, self.matrix))
def _image(self):
return self.codomain.submodule(*[self(x) for x in self.domain.gens])
def _kernel(self):
syz = self.image().syzygy_module()
return self.domain.submodule(
*[sum(xi*gi for xi, gi in zip(s, self.domain.gens))
for s in syz.gens])
def homomorphism(domain, codomain, matrix):
r"""
Create a homomorphism object.
This function tries to build a homomorphism from ``domain`` to ``codomain``
via the matrix ``matrix``.
Examples
========
>>> from sympy import QQ
>>> from sympy.abc import x
>>> from sympy.polys.agca import homomorphism
>>> R = QQ.old_poly_ring(x)
>>> T = R.free_module(2)
If ``domain`` is a free module generated by `e_1, \ldots, e_n`, then
``matrix`` should be an n-element iterable `(b_1, \ldots, b_n)` where
the `b_i` are elements of ``codomain``. The constructed homomorphism is the
unique homomorphism sending `e_i` to `b_i`.
>>> F = R.free_module(2)
>>> h = homomorphism(F, T, [[1, x], [x**2, 0]])
>>> h
Matrix([
[1, x**2], : QQ[x]**2 -> QQ[x]**2
[x, 0]])
>>> h([1, 0])
[1, x]
>>> h([0, 1])
[x**2, 0]
>>> h([1, 1])
[x**2 + 1, x]
If ``domain`` is a submodule of a free module, them ``matrix`` determines
a homomoprhism from the containing free module to ``codomain``, and the
homomorphism returned is obtained by restriction to ``domain``.
>>> S = F.submodule([1, 0], [0, x])
>>> homomorphism(S, T, [[1, x], [x**2, 0]])
Matrix([
[1, x**2], : <[1, 0], [0, x]> -> QQ[x]**2
[x, 0]])
If ``domain`` is a (sub)quotient `N/K`, then ``matrix`` determines a
homomorphism from `N` to ``codomain``. If the kernel contains `K`, this
homomorphism descends to ``domain`` and is returned; otherwise an exception
is raised.
>>> homomorphism(S/[(1, 0)], T, [0, [x**2, 0]])
Matrix([
[0, x**2], : <[1, 0] + <[1, 0]>, [0, x] + <[1, 0]>, [1, 0] + <[1, 0]>> -> QQ[x]**2
[0, 0]])
>>> homomorphism(S/[(0, x)], T, [0, [x**2, 0]])
Traceback (most recent call last):
...
ValueError: kernel <[1, 0], [0, 0]> must contain sm, got <[0,x]>
"""
def freepres(module):
"""
Return a tuple ``(F, S, Q, c)`` where ``F`` is a free module, ``S`` is a
submodule of ``F``, and ``Q`` a submodule of ``S``, such that
``module = S/Q``, and ``c`` is a conversion function.
"""
if isinstance(module, FreeModule):
return module, module, module.submodule(), lambda x: module.convert(x)
if isinstance(module, QuotientModule):
return (module.base, module.base, module.killed_module,
lambda x: module.convert(x).data)
if isinstance(module, SubQuotientModule):
return (module.base.container, module.base, module.killed_module,
lambda x: module.container.convert(x).data)
# an ordinary submodule
return (module.container, module, module.submodule(),
lambda x: module.container.convert(x))
SF, SS, SQ, _ = freepres(domain)
TF, TS, TQ, c = freepres(codomain)
# NOTE this is probably a bit inefficient (redundant checks)
return FreeModuleHomomorphism(SF, TF, [c(x) for x in matrix]
).restrict_domain(SS).restrict_codomain(TS
).quotient_codomain(TQ).quotient_domain(SQ)
|
b8822657fd45d32d5a7fabad60eeb93c3495c0b9c844ad80a39df7329a421233
|
# -*- coding: utf-8 -*-
from sympy import Integral, latex, Function
from sympy import pretty as xpretty
from sympy.vector import CoordSys3D, Vector, express
from sympy.abc import a, b, c
from sympy.core.compatibility import u_decode as u
from sympy.utilities.pytest import XFAIL
def pretty(expr):
"""ASCII pretty-printing"""
return xpretty(expr, use_unicode=False, wrap_line=False)
def upretty(expr):
"""Unicode pretty-printing"""
return xpretty(expr, use_unicode=True, wrap_line=False)
# Initialize the basic and tedious vector/dyadic expressions
# needed for testing.
# Some of the pretty forms shown denote how the expressions just
# above them should look with pretty printing.
N = CoordSys3D('N')
C = N.orient_new_axis('C', a, N.k)
v = []
d = []
v.append(Vector.zero)
v.append(N.i)
v.append(-N.i)
v.append(N.i + N.j)
v.append(a*N.i)
v.append(a*N.i - b*N.j)
v.append((a**2 + N.x)*N.i + N.k)
v.append((a**2 + b)*N.i + 3*(C.y - c)*N.k)
f = Function('f')
v.append(N.j - (Integral(f(b)) - C.x**2)*N.k)
upretty_v_8 = u(
"""\
⎛ 2 ⌠ ⎞ \n\
N_j + ⎜C_x - ⎮ f(b) db⎟ N_k\n\
⎝ ⌡ ⎠ \
""")
pretty_v_8 = u(
"""\
N_j + / / \\\n\
| 2 | |\n\
|C_x - | f(b) db|\n\
| | |\n\
\\ / / \
""")
v.append(N.i + C.k)
v.append(express(N.i, C))
v.append((a**2 + b)*N.i + (Integral(f(b)))*N.k)
upretty_v_11 = u(
"""\
⎛ 2 ⎞ ⎛⌠ ⎞ \n\
⎝a + b⎠ N_i + ⎜⎮ f(b) db⎟ N_k\n\
⎝⌡ ⎠ \
""")
pretty_v_11 = u(
"""\
/ 2 \\ + / / \\\n\
\\a + b/ N_i| | |\n\
| | f(b) db|\n\
| | |\n\
\\/ / \
""")
for x in v:
d.append(x | N.k)
s = 3*N.x**2*C.y
upretty_s = u(
"""\
2\n\
3⋅C_y⋅N_x \
""")
pretty_s = u(
"""\
2\n\
3*C_y*N_x \
""")
# This is the pretty form for ((a**2 + b)*N.i + 3*(C.y - c)*N.k) | N.k
upretty_d_7 = u(
"""\
⎛ 2 ⎞ \n\
⎝a + b⎠ (N_i|N_k) + (3⋅C_y - 3⋅c) (N_k|N_k)\
""")
pretty_d_7 = u(
"""\
/ 2 \\ (N_i|N_k) + (3*C_y - 3*c) (N_k|N_k)\n\
\\a + b/ \
""")
def test_str_printing():
assert str(v[0]) == '0'
assert str(v[1]) == 'N.i'
assert str(v[2]) == '(-1)*N.i'
assert str(v[3]) == 'N.i + N.j'
assert str(v[8]) == 'N.j + (C.x**2 - Integral(f(b), b))*N.k'
assert str(v[9]) == 'C.k + N.i'
assert str(s) == '3*C.y*N.x**2'
assert str(d[0]) == '0'
assert str(d[1]) == '(N.i|N.k)'
assert str(d[4]) == 'a*(N.i|N.k)'
assert str(d[5]) == 'a*(N.i|N.k) + (-b)*(N.j|N.k)'
assert str(d[8]) == ('(N.j|N.k) + (C.x**2 - ' +
'Integral(f(b), b))*(N.k|N.k)')
@XFAIL
def test_pretty_printing_ascii():
assert pretty(v[0]) == u'0'
assert pretty(v[1]) == u'N_i'
assert pretty(v[5]) == u'(a) N_i + (-b) N_j'
assert pretty(v[8]) == pretty_v_8
assert pretty(v[2]) == u'(-1) N_i'
assert pretty(v[11]) == pretty_v_11
assert pretty(s) == pretty_s
assert pretty(d[0]) == u'(0|0)'
assert pretty(d[5]) == u'(a) (N_i|N_k) + (-b) (N_j|N_k)'
assert pretty(d[7]) == pretty_d_7
assert pretty(d[10]) == u'(cos(a)) (C_i|N_k) + (-sin(a)) (C_j|N_k)'
def test_pretty_print_unicode():
assert upretty(v[0]) == u'0'
assert upretty(v[1]) == u'N_i'
assert upretty(v[5]) == u'(a) N_i + (-b) N_j'
# Make sure the printing works in other objects
assert upretty(v[5].args) == u'((a) N_i, (-b) N_j)'
assert upretty(v[8]) == upretty_v_8
assert upretty(v[2]) == u'(-1) N_i'
assert upretty(v[11]) == upretty_v_11
assert upretty(s) == upretty_s
assert upretty(d[0]) == u'(0|0)'
assert upretty(d[5]) == u'(a) (N_i|N_k) + (-b) (N_j|N_k)'
assert upretty(d[7]) == upretty_d_7
assert upretty(d[10]) == u'(cos(a)) (C_i|N_k) + (-sin(a)) (C_j|N_k)'
def test_latex_printing():
assert latex(v[0]) == '\\mathbf{\\hat{0}}'
assert latex(v[1]) == '\\mathbf{\\hat{i}_{N}}'
assert latex(v[2]) == '- \\mathbf{\\hat{i}_{N}}'
assert latex(v[5]) == ('(a)\\mathbf{\\hat{i}_{N}} + ' +
'(- b)\\mathbf{\\hat{j}_{N}}')
assert latex(v[6]) == ('(\\mathbf{{x}_{N}} + a^{2})\\mathbf{\\hat{i}_' +
'{N}} + \\mathbf{\\hat{k}_{N}}')
assert latex(v[8]) == ('\\mathbf{\\hat{j}_{N}} + (\\mathbf{{x}_' +
'{C}}^{2} - \\int f{\\left(b \\right)}\\,' +
' db)\\mathbf{\\hat{k}_{N}}')
assert latex(s) == '3 \\mathbf{{y}_{C}} \\mathbf{{x}_{N}}^{2}'
assert latex(d[0]) == '(\\mathbf{\\hat{0}}|\\mathbf{\\hat{0}})'
assert latex(d[4]) == ('(a)(\\mathbf{\\hat{i}_{N}}{|}\\mathbf' +
'{\\hat{k}_{N}})')
assert latex(d[9]) == ('(\\mathbf{\\hat{k}_{C}}{|}\\mathbf{\\' +
'hat{k}_{N}}) + (\\mathbf{\\hat{i}_{N}}{|' +
'}\\mathbf{\\hat{k}_{N}})')
assert latex(d[11]) == ('(a^{2} + b)(\\mathbf{\\hat{i}_{N}}{|}\\' +
'mathbf{\\hat{k}_{N}}) + (\\int f{\\left(' +
'b \\right)}\\, db)(\\mathbf{\\hat{k}_{N}' +
'}{|}\\mathbf{\\hat{k}_{N}})')
def test_custom_names():
A = CoordSys3D('A', vector_names=['x', 'y', 'z'],
variable_names=['i', 'j', 'k'])
assert A.i.__str__() == 'A.i'
assert A.x.__str__() == 'A.x'
assert A.i._pretty_form == 'A_i'
assert A.x._pretty_form == 'A_x'
assert A.i._latex_form == r'\mathbf{{i}_{A}}'
assert A.x._latex_form == r"\mathbf{\hat{x}_{A}}"
|
918a02c69a21e5a0c253e45ae825aac0875e460b94936c46992a03688b1efed9
|
"""Quantum mechanical angular momemtum."""
from __future__ import print_function, division
from sympy import (Add, binomial, cos, exp, Expr, factorial, I, Integer, Mul,
pi, Rational, S, sin, simplify, sqrt, Sum, symbols, sympify,
Tuple, Dummy)
from sympy.core.compatibility import unicode, range
from sympy.matrices import zeros
from sympy.printing.pretty.stringpict import prettyForm, stringPict
from sympy.printing.pretty.pretty_symbology import pretty_symbol
from sympy.physics.quantum.qexpr import QExpr
from sympy.physics.quantum.operator import (HermitianOperator, Operator,
UnitaryOperator)
from sympy.physics.quantum.state import Bra, Ket, State
from sympy.functions.special.tensor_functions import KroneckerDelta
from sympy.physics.quantum.constants import hbar
from sympy.physics.quantum.hilbert import ComplexSpace, DirectSumHilbertSpace
from sympy.physics.quantum.tensorproduct import TensorProduct
from sympy.physics.quantum.cg import CG
from sympy.physics.quantum.qapply import qapply
__all__ = [
'm_values',
'Jplus',
'Jminus',
'Jx',
'Jy',
'Jz',
'J2',
'Rotation',
'WignerD',
'JxKet',
'JxBra',
'JyKet',
'JyBra',
'JzKet',
'JzBra',
'JxKetCoupled',
'JxBraCoupled',
'JyKetCoupled',
'JyBraCoupled',
'JzKetCoupled',
'JzBraCoupled',
'couple',
'uncouple'
]
def m_values(j):
j = sympify(j)
size = 2*j + 1
if not size.is_Integer or not size > 0:
raise ValueError(
'Only integer or half-integer values allowed for j, got: : %r' % j
)
return size, [j - i for i in range(int(2*j + 1))]
#-----------------------------------------------------------------------------
# Spin Operators
#-----------------------------------------------------------------------------
class SpinOpBase(object):
"""Base class for spin operators."""
@classmethod
def _eval_hilbert_space(cls, label):
# We consider all j values so our space is infinite.
return ComplexSpace(S.Infinity)
@property
def name(self):
return self.args[0]
def _print_contents(self, printer, *args):
return '%s%s' % (unicode(self.name), self._coord)
def _print_contents_pretty(self, printer, *args):
a = stringPict(unicode(self.name))
b = stringPict(self._coord)
return self._print_subscript_pretty(a, b)
def _print_contents_latex(self, printer, *args):
return r'%s_%s' % ((unicode(self.name), self._coord))
def _represent_base(self, basis, **options):
j = options.get('j', Rational(1, 2))
size, mvals = m_values(j)
result = zeros(size, size)
for p in range(size):
for q in range(size):
me = self.matrix_element(j, mvals[p], j, mvals[q])
result[p, q] = me
return result
def _apply_op(self, ket, orig_basis, **options):
state = ket.rewrite(self.basis)
# If the state has only one term
if isinstance(state, State):
ret = (hbar*state.m) * state
# state is a linear combination of states
elif isinstance(state, Sum):
ret = self._apply_operator_Sum(state, **options)
else:
ret = qapply(self*state)
if ret == self*state:
raise NotImplementedError
return ret.rewrite(orig_basis)
def _apply_operator_JxKet(self, ket, **options):
return self._apply_op(ket, 'Jx', **options)
def _apply_operator_JxKetCoupled(self, ket, **options):
return self._apply_op(ket, 'Jx', **options)
def _apply_operator_JyKet(self, ket, **options):
return self._apply_op(ket, 'Jy', **options)
def _apply_operator_JyKetCoupled(self, ket, **options):
return self._apply_op(ket, 'Jy', **options)
def _apply_operator_JzKet(self, ket, **options):
return self._apply_op(ket, 'Jz', **options)
def _apply_operator_JzKetCoupled(self, ket, **options):
return self._apply_op(ket, 'Jz', **options)
def _apply_operator_TensorProduct(self, tp, **options):
# Uncoupling operator is only easily found for coordinate basis spin operators
# TODO: add methods for uncoupling operators
if not (isinstance(self, JxOp) or isinstance(self, JyOp) or isinstance(self, JzOp)):
raise NotImplementedError
result = []
for n in range(len(tp.args)):
arg = []
arg.extend(tp.args[:n])
arg.append(self._apply_operator(tp.args[n]))
arg.extend(tp.args[n + 1:])
result.append(tp.__class__(*arg))
return Add(*result).expand()
# TODO: move this to qapply_Mul
def _apply_operator_Sum(self, s, **options):
new_func = qapply(self * s.function)
if new_func == self*s.function:
raise NotImplementedError
return Sum(new_func, *s.limits)
def _eval_trace(self, **options):
#TODO: use options to use different j values
#For now eval at default basis
# is it efficient to represent each time
# to do a trace?
return self._represent_default_basis().trace()
class JplusOp(SpinOpBase, Operator):
"""The J+ operator."""
_coord = '+'
basis = 'Jz'
def _eval_commutator_JminusOp(self, other):
return 2*hbar*JzOp(self.name)
def _apply_operator_JzKet(self, ket, **options):
j = ket.j
m = ket.m
if m.is_Number and j.is_Number:
if m >= j:
return S.Zero
return hbar*sqrt(j*(j + S.One) - m*(m + S.One))*JzKet(j, m + S.One)
def _apply_operator_JzKetCoupled(self, ket, **options):
j = ket.j
m = ket.m
jn = ket.jn
coupling = ket.coupling
if m.is_Number and j.is_Number:
if m >= j:
return S.Zero
return hbar*sqrt(j*(j + S.One) - m*(m + S.One))*JzKetCoupled(j, m + S.One, jn, coupling)
def matrix_element(self, j, m, jp, mp):
result = hbar*sqrt(j*(j + S.One) - mp*(mp + S.One))
result *= KroneckerDelta(m, mp + 1)
result *= KroneckerDelta(j, jp)
return result
def _represent_default_basis(self, **options):
return self._represent_JzOp(None, **options)
def _represent_JzOp(self, basis, **options):
return self._represent_base(basis, **options)
def _eval_rewrite_as_xyz(self, *args, **kwargs):
return JxOp(args[0]) + I*JyOp(args[0])
class JminusOp(SpinOpBase, Operator):
"""The J- operator."""
_coord = '-'
basis = 'Jz'
def _apply_operator_JzKet(self, ket, **options):
j = ket.j
m = ket.m
if m.is_Number and j.is_Number:
if m <= -j:
return S.Zero
return hbar*sqrt(j*(j + S.One) - m*(m - S.One))*JzKet(j, m - S.One)
def _apply_operator_JzKetCoupled(self, ket, **options):
j = ket.j
m = ket.m
jn = ket.jn
coupling = ket.coupling
if m.is_Number and j.is_Number:
if m <= -j:
return S.Zero
return hbar*sqrt(j*(j + S.One) - m*(m - S.One))*JzKetCoupled(j, m - S.One, jn, coupling)
def matrix_element(self, j, m, jp, mp):
result = hbar*sqrt(j*(j + S.One) - mp*(mp - S.One))
result *= KroneckerDelta(m, mp - 1)
result *= KroneckerDelta(j, jp)
return result
def _represent_default_basis(self, **options):
return self._represent_JzOp(None, **options)
def _represent_JzOp(self, basis, **options):
return self._represent_base(basis, **options)
def _eval_rewrite_as_xyz(self, *args, **kwargs):
return JxOp(args[0]) - I*JyOp(args[0])
class JxOp(SpinOpBase, HermitianOperator):
"""The Jx operator."""
_coord = 'x'
basis = 'Jx'
def _eval_commutator_JyOp(self, other):
return I*hbar*JzOp(self.name)
def _eval_commutator_JzOp(self, other):
return -I*hbar*JyOp(self.name)
def _apply_operator_JzKet(self, ket, **options):
jp = JplusOp(self.name)._apply_operator_JzKet(ket, **options)
jm = JminusOp(self.name)._apply_operator_JzKet(ket, **options)
return (jp + jm)/Integer(2)
def _apply_operator_JzKetCoupled(self, ket, **options):
jp = JplusOp(self.name)._apply_operator_JzKetCoupled(ket, **options)
jm = JminusOp(self.name)._apply_operator_JzKetCoupled(ket, **options)
return (jp + jm)/Integer(2)
def _represent_default_basis(self, **options):
return self._represent_JzOp(None, **options)
def _represent_JzOp(self, basis, **options):
jp = JplusOp(self.name)._represent_JzOp(basis, **options)
jm = JminusOp(self.name)._represent_JzOp(basis, **options)
return (jp + jm)/Integer(2)
def _eval_rewrite_as_plusminus(self, *args, **kwargs):
return (JplusOp(args[0]) + JminusOp(args[0]))/2
class JyOp(SpinOpBase, HermitianOperator):
"""The Jy operator."""
_coord = 'y'
basis = 'Jy'
def _eval_commutator_JzOp(self, other):
return I*hbar*JxOp(self.name)
def _eval_commutator_JxOp(self, other):
return -I*hbar*J2Op(self.name)
def _apply_operator_JzKet(self, ket, **options):
jp = JplusOp(self.name)._apply_operator_JzKet(ket, **options)
jm = JminusOp(self.name)._apply_operator_JzKet(ket, **options)
return (jp - jm)/(Integer(2)*I)
def _apply_operator_JzKetCoupled(self, ket, **options):
jp = JplusOp(self.name)._apply_operator_JzKetCoupled(ket, **options)
jm = JminusOp(self.name)._apply_operator_JzKetCoupled(ket, **options)
return (jp - jm)/(Integer(2)*I)
def _represent_default_basis(self, **options):
return self._represent_JzOp(None, **options)
def _represent_JzOp(self, basis, **options):
jp = JplusOp(self.name)._represent_JzOp(basis, **options)
jm = JminusOp(self.name)._represent_JzOp(basis, **options)
return (jp - jm)/(Integer(2)*I)
def _eval_rewrite_as_plusminus(self, *args, **kwargs):
return (JplusOp(args[0]) - JminusOp(args[0]))/(2*I)
class JzOp(SpinOpBase, HermitianOperator):
"""The Jz operator."""
_coord = 'z'
basis = 'Jz'
def _eval_commutator_JxOp(self, other):
return I*hbar*JyOp(self.name)
def _eval_commutator_JyOp(self, other):
return -I*hbar*JxOp(self.name)
def _eval_commutator_JplusOp(self, other):
return hbar*JplusOp(self.name)
def _eval_commutator_JminusOp(self, other):
return -hbar*JminusOp(self.name)
def matrix_element(self, j, m, jp, mp):
result = hbar*mp
result *= KroneckerDelta(m, mp)
result *= KroneckerDelta(j, jp)
return result
def _represent_default_basis(self, **options):
return self._represent_JzOp(None, **options)
def _represent_JzOp(self, basis, **options):
return self._represent_base(basis, **options)
class J2Op(SpinOpBase, HermitianOperator):
"""The J^2 operator."""
_coord = '2'
def _eval_commutator_JxOp(self, other):
return S.Zero
def _eval_commutator_JyOp(self, other):
return S.Zero
def _eval_commutator_JzOp(self, other):
return S.Zero
def _eval_commutator_JplusOp(self, other):
return S.Zero
def _eval_commutator_JminusOp(self, other):
return S.Zero
def _apply_operator_JxKet(self, ket, **options):
j = ket.j
return hbar**2*j*(j + 1)*ket
def _apply_operator_JxKetCoupled(self, ket, **options):
j = ket.j
return hbar**2*j*(j + 1)*ket
def _apply_operator_JyKet(self, ket, **options):
j = ket.j
return hbar**2*j*(j + 1)*ket
def _apply_operator_JyKetCoupled(self, ket, **options):
j = ket.j
return hbar**2*j*(j + 1)*ket
def _apply_operator_JzKet(self, ket, **options):
j = ket.j
return hbar**2*j*(j + 1)*ket
def _apply_operator_JzKetCoupled(self, ket, **options):
j = ket.j
return hbar**2*j*(j + 1)*ket
def matrix_element(self, j, m, jp, mp):
result = (hbar**2)*j*(j + 1)
result *= KroneckerDelta(m, mp)
result *= KroneckerDelta(j, jp)
return result
def _represent_default_basis(self, **options):
return self._represent_JzOp(None, **options)
def _represent_JzOp(self, basis, **options):
return self._represent_base(basis, **options)
def _print_contents_pretty(self, printer, *args):
a = prettyForm(unicode(self.name))
b = prettyForm(u'2')
return a**b
def _print_contents_latex(self, printer, *args):
return r'%s^2' % str(self.name)
def _eval_rewrite_as_xyz(self, *args, **kwargs):
return JxOp(args[0])**2 + JyOp(args[0])**2 + JzOp(args[0])**2
def _eval_rewrite_as_plusminus(self, *args, **kwargs):
a = args[0]
return JzOp(a)**2 + \
Rational(1, 2)*(JplusOp(a)*JminusOp(a) + JminusOp(a)*JplusOp(a))
class Rotation(UnitaryOperator):
"""Wigner D operator in terms of Euler angles.
Defines the rotation operator in terms of the Euler angles defined by
the z-y-z convention for a passive transformation. That is the coordinate
axes are rotated first about the z-axis, giving the new x'-y'-z' axes. Then
this new coordinate system is rotated about the new y'-axis, giving new
x''-y''-z'' axes. Then this new coordinate system is rotated about the
z''-axis. Conventions follow those laid out in [1]_.
Parameters
==========
alpha : Number, Symbol
First Euler Angle
beta : Number, Symbol
Second Euler angle
gamma : Number, Symbol
Third Euler angle
Examples
========
A simple example rotation operator:
>>> from sympy import pi
>>> from sympy.physics.quantum.spin import Rotation
>>> Rotation(pi, 0, pi/2)
R(pi,0,pi/2)
With symbolic Euler angles and calculating the inverse rotation operator:
>>> from sympy import symbols
>>> a, b, c = symbols('a b c')
>>> Rotation(a, b, c)
R(a,b,c)
>>> Rotation(a, b, c).inverse()
R(-c,-b,-a)
See Also
========
WignerD: Symbolic Wigner-D function
D: Wigner-D function
d: Wigner small-d function
References
==========
.. [1] Varshalovich, D A, Quantum Theory of Angular Momentum. 1988.
"""
@classmethod
def _eval_args(cls, args):
args = QExpr._eval_args(args)
if len(args) != 3:
raise ValueError('3 Euler angles required, got: %r' % args)
return args
@classmethod
def _eval_hilbert_space(cls, label):
# We consider all j values so our space is infinite.
return ComplexSpace(S.Infinity)
@property
def alpha(self):
return self.label[0]
@property
def beta(self):
return self.label[1]
@property
def gamma(self):
return self.label[2]
def _print_operator_name(self, printer, *args):
return 'R'
def _print_operator_name_pretty(self, printer, *args):
if printer._use_unicode:
return prettyForm(u'\N{SCRIPT CAPITAL R}' + u' ')
else:
return prettyForm("R ")
def _print_operator_name_latex(self, printer, *args):
return r'\mathcal{R}'
def _eval_inverse(self):
return Rotation(-self.gamma, -self.beta, -self.alpha)
@classmethod
def D(cls, j, m, mp, alpha, beta, gamma):
"""Wigner D-function.
Returns an instance of the WignerD class corresponding to the Wigner-D
function specified by the parameters.
Parameters
===========
j : Number
Total angular momentum
m : Number
Eigenvalue of angular momentum along axis after rotation
mp : Number
Eigenvalue of angular momentum along rotated axis
alpha : Number, Symbol
First Euler angle of rotation
beta : Number, Symbol
Second Euler angle of rotation
gamma : Number, Symbol
Third Euler angle of rotation
Examples
========
Return the Wigner-D matrix element for a defined rotation, both
numerical and symbolic:
>>> from sympy.physics.quantum.spin import Rotation
>>> from sympy import pi, symbols
>>> alpha, beta, gamma = symbols('alpha beta gamma')
>>> Rotation.D(1, 1, 0,pi, pi/2,-pi)
WignerD(1, 1, 0, pi, pi/2, -pi)
See Also
========
WignerD: Symbolic Wigner-D function
"""
return WignerD(j, m, mp, alpha, beta, gamma)
@classmethod
def d(cls, j, m, mp, beta):
"""Wigner small-d function.
Returns an instance of the WignerD class corresponding to the Wigner-D
function specified by the parameters with the alpha and gamma angles
given as 0.
Parameters
===========
j : Number
Total angular momentum
m : Number
Eigenvalue of angular momentum along axis after rotation
mp : Number
Eigenvalue of angular momentum along rotated axis
beta : Number, Symbol
Second Euler angle of rotation
Examples
========
Return the Wigner-D matrix element for a defined rotation, both
numerical and symbolic:
>>> from sympy.physics.quantum.spin import Rotation
>>> from sympy import pi, symbols
>>> beta = symbols('beta')
>>> Rotation.d(1, 1, 0, pi/2)
WignerD(1, 1, 0, 0, pi/2, 0)
See Also
========
WignerD: Symbolic Wigner-D function
"""
return WignerD(j, m, mp, 0, beta, 0)
def matrix_element(self, j, m, jp, mp):
result = self.__class__.D(
jp, m, mp, self.alpha, self.beta, self.gamma
)
result *= KroneckerDelta(j, jp)
return result
def _represent_base(self, basis, **options):
j = sympify(options.get('j', Rational(1, 2)))
# TODO: move evaluation up to represent function/implement elsewhere
evaluate = sympify(options.get('doit'))
size, mvals = m_values(j)
result = zeros(size, size)
for p in range(size):
for q in range(size):
me = self.matrix_element(j, mvals[p], j, mvals[q])
if evaluate:
result[p, q] = me.doit()
else:
result[p, q] = me
return result
def _represent_default_basis(self, **options):
return self._represent_JzOp(None, **options)
def _represent_JzOp(self, basis, **options):
return self._represent_base(basis, **options)
def _apply_operator_uncoupled(self, state, ket, **options):
a = self.alpha
b = self.beta
g = self.gamma
j = ket.j
m = ket.m
if j.is_number:
s = []
size = m_values(j)
sz = size[1]
for mp in sz:
r = Rotation.D(j, m, mp, a, b, g)
z = r.doit()
s.append(z * state(j, mp))
return Add(*s)
else:
if options.pop('dummy', True):
mp = Dummy('mp')
else:
mp = symbols('mp')
return Sum(Rotation.D(j, m, mp, a, b, g) * state(j, mp), (mp, -j, j))
def _apply_operator_JxKet(self, ket, **options):
return self._apply_operator_uncoupled(JxKet, ket, **options)
def _apply_operator_JyKet(self, ket, **options):
return self._apply_operator_uncoupled(JyKet, ket, **options)
def _apply_operator_JzKet(self, ket, **options):
return self._apply_operator_uncoupled(JzKet, ket, **options)
def _apply_operator_coupled(self, state, ket, **options):
a = self.alpha
b = self.beta
g = self.gamma
j = ket.j
m = ket.m
jn = ket.jn
coupling = ket.coupling
if j.is_number:
s = []
size = m_values(j)
sz = size[1]
for mp in sz:
r = Rotation.D(j, m, mp, a, b, g)
z = r.doit()
s.append(z * state(j, mp, jn, coupling))
return Add(*s)
else:
if options.pop('dummy', True):
mp = Dummy('mp')
else:
mp = symbols('mp')
return Sum(Rotation.D(j, m, mp, a, b, g) * state(
j, mp, jn, coupling), (mp, -j, j))
def _apply_operator_JxKetCoupled(self, ket, **options):
return self._apply_operator_coupled(JxKetCoupled, ket, **options)
def _apply_operator_JyKetCoupled(self, ket, **options):
return self._apply_operator_coupled(JyKetCoupled, ket, **options)
def _apply_operator_JzKetCoupled(self, ket, **options):
return self._apply_operator_coupled(JzKetCoupled, ket, **options)
class WignerD(Expr):
r"""Wigner-D function
The Wigner D-function gives the matrix elements of the rotation
operator in the jm-representation. For the Euler angles `\alpha`,
`\beta`, `\gamma`, the D-function is defined such that:
.. math ::
<j,m| \mathcal{R}(\alpha, \beta, \gamma ) |j',m'> = \delta_{jj'} D(j, m, m', \alpha, \beta, \gamma)
Where the rotation operator is as defined by the Rotation class [1]_.
The Wigner D-function defined in this way gives:
.. math ::
D(j, m, m', \alpha, \beta, \gamma) = e^{-i m \alpha} d(j, m, m', \beta) e^{-i m' \gamma}
Where d is the Wigner small-d function, which is given by Rotation.d.
The Wigner small-d function gives the component of the Wigner
D-function that is determined by the second Euler angle. That is the
Wigner D-function is:
.. math ::
D(j, m, m', \alpha, \beta, \gamma) = e^{-i m \alpha} d(j, m, m', \beta) e^{-i m' \gamma}
Where d is the small-d function. The Wigner D-function is given by
Rotation.D.
Note that to evaluate the D-function, the j, m and mp parameters must
be integer or half integer numbers.
Parameters
==========
j : Number
Total angular momentum
m : Number
Eigenvalue of angular momentum along axis after rotation
mp : Number
Eigenvalue of angular momentum along rotated axis
alpha : Number, Symbol
First Euler angle of rotation
beta : Number, Symbol
Second Euler angle of rotation
gamma : Number, Symbol
Third Euler angle of rotation
Examples
========
Evaluate the Wigner-D matrix elements of a simple rotation:
>>> from sympy.physics.quantum.spin import Rotation
>>> from sympy import pi
>>> rot = Rotation.D(1, 1, 0, pi, pi/2, 0)
>>> rot
WignerD(1, 1, 0, pi, pi/2, 0)
>>> rot.doit()
sqrt(2)/2
Evaluate the Wigner-d matrix elements of a simple rotation
>>> rot = Rotation.d(1, 1, 0, pi/2)
>>> rot
WignerD(1, 1, 0, 0, pi/2, 0)
>>> rot.doit()
-sqrt(2)/2
See Also
========
Rotation: Rotation operator
References
==========
.. [1] Varshalovich, D A, Quantum Theory of Angular Momentum. 1988.
"""
is_commutative = True
def __new__(cls, *args, **hints):
if not len(args) == 6:
raise ValueError('6 parameters expected, got %s' % args)
args = sympify(args)
evaluate = hints.get('evaluate', False)
if evaluate:
return Expr.__new__(cls, *args)._eval_wignerd()
return Expr.__new__(cls, *args)
@property
def j(self):
return self.args[0]
@property
def m(self):
return self.args[1]
@property
def mp(self):
return self.args[2]
@property
def alpha(self):
return self.args[3]
@property
def beta(self):
return self.args[4]
@property
def gamma(self):
return self.args[5]
def _latex(self, printer, *args):
if self.alpha == 0 and self.gamma == 0:
return r'd^{%s}_{%s,%s}\left(%s\right)' % \
(
printer._print(self.j), printer._print(
self.m), printer._print(self.mp),
printer._print(self.beta) )
return r'D^{%s}_{%s,%s}\left(%s,%s,%s\right)' % \
(
printer._print(
self.j), printer._print(self.m), printer._print(self.mp),
printer._print(self.alpha), printer._print(self.beta), printer._print(self.gamma) )
def _pretty(self, printer, *args):
top = printer._print(self.j)
bot = printer._print(self.m)
bot = prettyForm(*bot.right(','))
bot = prettyForm(*bot.right(printer._print(self.mp)))
pad = max(top.width(), bot.width())
top = prettyForm(*top.left(' '))
bot = prettyForm(*bot.left(' '))
if pad > top.width():
top = prettyForm(*top.right(' ' * (pad - top.width())))
if pad > bot.width():
bot = prettyForm(*bot.right(' ' * (pad - bot.width())))
if self.alpha == 0 and self.gamma == 0:
args = printer._print(self.beta)
s = stringPict('d' + ' '*pad)
else:
args = printer._print(self.alpha)
args = prettyForm(*args.right(','))
args = prettyForm(*args.right(printer._print(self.beta)))
args = prettyForm(*args.right(','))
args = prettyForm(*args.right(printer._print(self.gamma)))
s = stringPict('D' + ' '*pad)
args = prettyForm(*args.parens())
s = prettyForm(*s.above(top))
s = prettyForm(*s.below(bot))
s = prettyForm(*s.right(args))
return s
def doit(self, **hints):
hints['evaluate'] = True
return WignerD(*self.args, **hints)
def _eval_wignerd(self):
j = sympify(self.j)
m = sympify(self.m)
mp = sympify(self.mp)
alpha = sympify(self.alpha)
beta = sympify(self.beta)
gamma = sympify(self.gamma)
if not j.is_number:
raise ValueError(
'j parameter must be numerical to evaluate, got %s' % j)
r = 0
if beta == pi/2:
# Varshalovich Equation (5), Section 4.16, page 113, setting
# alpha=gamma=0.
for k in range(2*j + 1):
if k > j + mp or k > j - m or k < mp - m:
continue
r += (-S(1))**k * binomial(j + mp, k) * binomial(j - mp, k + m - mp)
r *= (-S(1))**(m - mp) / 2**j * sqrt(factorial(j + m) *
factorial(j - m) / (factorial(j + mp) * factorial(j - mp)))
else:
# Varshalovich Equation(5), Section 4.7.2, page 87, where we set
# beta1=beta2=pi/2, and we get alpha=gamma=pi/2 and beta=phi+pi,
# then we use the Eq. (1), Section 4.4. page 79, to simplify:
# d(j, m, mp, beta+pi) = (-1)**(j-mp) * d(j, m, -mp, beta)
# This happens to be almost the same as in Eq.(10), Section 4.16,
# except that we need to substitute -mp for mp.
size, mvals = m_values(j)
for mpp in mvals:
r += Rotation.d(j, m, mpp, pi/2).doit() * (cos(-mpp*beta) + I*sin(-mpp*beta)) * \
Rotation.d(j, mpp, -mp, pi/2).doit()
# Empirical normalization factor so results match Varshalovich
# Tables 4.3-4.12
# Note that this exact normalization does not follow from the
# above equations
r = r * I**(2*j - m - mp) * (-1)**(2*m)
# Finally, simplify the whole expression
r = simplify(r)
r *= exp(-I*m*alpha)*exp(-I*mp*gamma)
return r
Jx = JxOp('J')
Jy = JyOp('J')
Jz = JzOp('J')
J2 = J2Op('J')
Jplus = JplusOp('J')
Jminus = JminusOp('J')
#-----------------------------------------------------------------------------
# Spin States
#-----------------------------------------------------------------------------
class SpinState(State):
"""Base class for angular momentum states."""
_label_separator = ','
def __new__(cls, j, m):
j = sympify(j)
m = sympify(m)
if j.is_number:
if 2*j != int(2*j):
raise ValueError(
'j must be integer or half-integer, got: %s' % j)
if j < 0:
raise ValueError('j must be >= 0, got: %s' % j)
if m.is_number:
if 2*m != int(2*m):
raise ValueError(
'm must be integer or half-integer, got: %s' % m)
if j.is_number and m.is_number:
if abs(m) > j:
raise ValueError('Allowed values for m are -j <= m <= j, got j, m: %s, %s' % (j, m))
if int(j - m) != j - m:
raise ValueError('Both j and m must be integer or half-integer, got j, m: %s, %s' % (j, m))
return State.__new__(cls, j, m)
@property
def j(self):
return self.label[0]
@property
def m(self):
return self.label[1]
@classmethod
def _eval_hilbert_space(cls, label):
return ComplexSpace(2*label[0] + 1)
def _represent_base(self, **options):
j = self.j
m = self.m
alpha = sympify(options.get('alpha', 0))
beta = sympify(options.get('beta', 0))
gamma = sympify(options.get('gamma', 0))
size, mvals = m_values(j)
result = zeros(size, 1)
# TODO: Use KroneckerDelta if all Euler angles == 0
# breaks finding angles on L930
for p, mval in enumerate(mvals):
if m.is_number:
result[p, 0] = Rotation.D(
self.j, mval, self.m, alpha, beta, gamma).doit()
else:
result[p, 0] = Rotation.D(self.j, mval,
self.m, alpha, beta, gamma)
return result
def _eval_rewrite_as_Jx(self, *args, **options):
if isinstance(self, Bra):
return self._rewrite_basis(Jx, JxBra, **options)
return self._rewrite_basis(Jx, JxKet, **options)
def _eval_rewrite_as_Jy(self, *args, **options):
if isinstance(self, Bra):
return self._rewrite_basis(Jy, JyBra, **options)
return self._rewrite_basis(Jy, JyKet, **options)
def _eval_rewrite_as_Jz(self, *args, **options):
if isinstance(self, Bra):
return self._rewrite_basis(Jz, JzBra, **options)
return self._rewrite_basis(Jz, JzKet, **options)
def _rewrite_basis(self, basis, evect, **options):
from sympy.physics.quantum.represent import represent
j = self.j
args = self.args[2:]
if j.is_number:
if isinstance(self, CoupledSpinState):
if j == int(j):
start = j**2
else:
start = (2*j - 1)*(2*j + 1)/4
else:
start = 0
vect = represent(self, basis=basis, **options)
result = Add(
*[vect[start + i] * evect(j, j - i, *args) for i in range(2*j + 1)])
if isinstance(self, CoupledSpinState) and options.get('coupled') is False:
return uncouple(result)
return result
else:
i = 0
mi = symbols('mi')
# make sure not to introduce a symbol already in the state
while self.subs(mi, 0) != self:
i += 1
mi = symbols('mi%d' % i)
break
# TODO: better way to get angles of rotation
if isinstance(self, CoupledSpinState):
test_args = (0, mi, (0, 0))
else:
test_args = (0, mi)
if isinstance(self, Ket):
angles = represent(
self.__class__(*test_args), basis=basis)[0].args[3:6]
else:
angles = represent(self.__class__(
*test_args), basis=basis)[0].args[0].args[3:6]
if angles == (0, 0, 0):
return self
else:
state = evect(j, mi, *args)
lt = Rotation.D(j, mi, self.m, *angles)
return Sum(lt * state, (mi, -j, j))
def _eval_innerproduct_JxBra(self, bra, **hints):
result = KroneckerDelta(self.j, bra.j)
if bra.dual_class() is not self.__class__:
result *= self._represent_JxOp(None)[bra.j - bra.m]
else:
result *= KroneckerDelta(
self.j, bra.j) * KroneckerDelta(self.m, bra.m)
return result
def _eval_innerproduct_JyBra(self, bra, **hints):
result = KroneckerDelta(self.j, bra.j)
if bra.dual_class() is not self.__class__:
result *= self._represent_JyOp(None)[bra.j - bra.m]
else:
result *= KroneckerDelta(
self.j, bra.j) * KroneckerDelta(self.m, bra.m)
return result
def _eval_innerproduct_JzBra(self, bra, **hints):
result = KroneckerDelta(self.j, bra.j)
if bra.dual_class() is not self.__class__:
result *= self._represent_JzOp(None)[bra.j - bra.m]
else:
result *= KroneckerDelta(
self.j, bra.j) * KroneckerDelta(self.m, bra.m)
return result
def _eval_trace(self, bra, **hints):
# One way to implement this method is to assume the basis set k is
# passed.
# Then we can apply the discrete form of Trace formula here
# Tr(|i><j| ) = \Sum_k <k|i><j|k>
#then we do qapply() on each each inner product and sum over them.
# OR
# Inner product of |i><j| = Trace(Outer Product).
# we could just use this unless there are cases when this is not true
return (bra*self).doit()
class JxKet(SpinState, Ket):
"""Eigenket of Jx.
See JzKet for the usage of spin eigenstates.
See Also
========
JzKet: Usage of spin states
"""
@classmethod
def dual_class(self):
return JxBra
@classmethod
def coupled_class(self):
return JxKetCoupled
def _represent_default_basis(self, **options):
return self._represent_JxOp(None, **options)
def _represent_JxOp(self, basis, **options):
return self._represent_base(**options)
def _represent_JyOp(self, basis, **options):
return self._represent_base(alpha=3*pi/2, **options)
def _represent_JzOp(self, basis, **options):
return self._represent_base(beta=pi/2, **options)
class JxBra(SpinState, Bra):
"""Eigenbra of Jx.
See JzKet for the usage of spin eigenstates.
See Also
========
JzKet: Usage of spin states
"""
@classmethod
def dual_class(self):
return JxKet
@classmethod
def coupled_class(self):
return JxBraCoupled
class JyKet(SpinState, Ket):
"""Eigenket of Jy.
See JzKet for the usage of spin eigenstates.
See Also
========
JzKet: Usage of spin states
"""
@classmethod
def dual_class(self):
return JyBra
@classmethod
def coupled_class(self):
return JyKetCoupled
def _represent_default_basis(self, **options):
return self._represent_JyOp(None, **options)
def _represent_JxOp(self, basis, **options):
return self._represent_base(gamma=pi/2, **options)
def _represent_JyOp(self, basis, **options):
return self._represent_base(**options)
def _represent_JzOp(self, basis, **options):
return self._represent_base(alpha=3*pi/2, beta=-pi/2, gamma=pi/2, **options)
class JyBra(SpinState, Bra):
"""Eigenbra of Jy.
See JzKet for the usage of spin eigenstates.
See Also
========
JzKet: Usage of spin states
"""
@classmethod
def dual_class(self):
return JyKet
@classmethod
def coupled_class(self):
return JyBraCoupled
class JzKet(SpinState, Ket):
"""Eigenket of Jz.
Spin state which is an eigenstate of the Jz operator. Uncoupled states,
that is states representing the interaction of multiple separate spin
states, are defined as a tensor product of states.
Parameters
==========
j : Number, Symbol
Total spin angular momentum
m : Number, Symbol
Eigenvalue of the Jz spin operator
Examples
========
*Normal States:*
Defining simple spin states, both numerical and symbolic:
>>> from sympy.physics.quantum.spin import JzKet, JxKet
>>> from sympy import symbols
>>> JzKet(1, 0)
|1,0>
>>> j, m = symbols('j m')
>>> JzKet(j, m)
|j,m>
Rewriting the JzKet in terms of eigenkets of the Jx operator:
Note: that the resulting eigenstates are JxKet's
>>> JzKet(1,1).rewrite("Jx")
|1,-1>/2 - sqrt(2)*|1,0>/2 + |1,1>/2
Get the vector representation of a state in terms of the basis elements
of the Jx operator:
>>> from sympy.physics.quantum.represent import represent
>>> from sympy.physics.quantum.spin import Jx, Jz
>>> represent(JzKet(1,-1), basis=Jx)
Matrix([
[ 1/2],
[sqrt(2)/2],
[ 1/2]])
Apply innerproducts between states:
>>> from sympy.physics.quantum.innerproduct import InnerProduct
>>> from sympy.physics.quantum.spin import JxBra
>>> i = InnerProduct(JxBra(1,1), JzKet(1,1))
>>> i
<1,1|1,1>
>>> i.doit()
1/2
*Uncoupled States:*
Define an uncoupled state as a TensorProduct between two Jz eigenkets:
>>> from sympy.physics.quantum.tensorproduct import TensorProduct
>>> j1,m1,j2,m2 = symbols('j1 m1 j2 m2')
>>> TensorProduct(JzKet(1,0), JzKet(1,1))
|1,0>x|1,1>
>>> TensorProduct(JzKet(j1,m1), JzKet(j2,m2))
|j1,m1>x|j2,m2>
A TensorProduct can be rewritten, in which case the eigenstates that make
up the tensor product is rewritten to the new basis:
>>> TensorProduct(JzKet(1,1),JxKet(1,1)).rewrite('Jz')
|1,1>x|1,-1>/2 + sqrt(2)*|1,1>x|1,0>/2 + |1,1>x|1,1>/2
The represent method for TensorProduct's gives the vector representation of
the state. Note that the state in the product basis is the equivalent of the
tensor product of the vector representation of the component eigenstates:
>>> represent(TensorProduct(JzKet(1,0),JzKet(1,1)))
Matrix([
[0],
[0],
[0],
[1],
[0],
[0],
[0],
[0],
[0]])
>>> represent(TensorProduct(JzKet(1,1),JxKet(1,1)), basis=Jz)
Matrix([
[ 1/2],
[sqrt(2)/2],
[ 1/2],
[ 0],
[ 0],
[ 0],
[ 0],
[ 0],
[ 0]])
See Also
========
JzKetCoupled: Coupled eigenstates
TensorProduct: Used to specify uncoupled states
uncouple: Uncouples states given coupling parameters
couple: Couples uncoupled states
"""
@classmethod
def dual_class(self):
return JzBra
@classmethod
def coupled_class(self):
return JzKetCoupled
def _represent_default_basis(self, **options):
return self._represent_JzOp(None, **options)
def _represent_JxOp(self, basis, **options):
return self._represent_base(beta=3*pi/2, **options)
def _represent_JyOp(self, basis, **options):
return self._represent_base(alpha=3*pi/2, beta=pi/2, gamma=pi/2, **options)
def _represent_JzOp(self, basis, **options):
return self._represent_base(**options)
class JzBra(SpinState, Bra):
"""Eigenbra of Jz.
See the JzKet for the usage of spin eigenstates.
See Also
========
JzKet: Usage of spin states
"""
@classmethod
def dual_class(self):
return JzKet
@classmethod
def coupled_class(self):
return JzBraCoupled
# Method used primarily to create coupled_n and coupled_jn by __new__ in
# CoupledSpinState
# This same method is also used by the uncouple method, and is separated from
# the CoupledSpinState class to maintain consistency in defining coupling
def _build_coupled(jcoupling, length):
n_list = [ [n + 1] for n in range(length) ]
coupled_jn = []
coupled_n = []
for n1, n2, j_new in jcoupling:
coupled_jn.append(j_new)
coupled_n.append( (n_list[n1 - 1], n_list[n2 - 1]) )
n_sort = sorted(n_list[n1 - 1] + n_list[n2 - 1])
n_list[n_sort[0] - 1] = n_sort
return coupled_n, coupled_jn
class CoupledSpinState(SpinState):
"""Base class for coupled angular momentum states."""
def __new__(cls, j, m, jn, *jcoupling):
# Check j and m values using SpinState
SpinState(j, m)
# Build and check coupling scheme from arguments
if len(jcoupling) == 0:
# Use default coupling scheme
jcoupling = []
for n in range(2, len(jn)):
jcoupling.append( (1, n, Add(*[jn[i] for i in range(n)])) )
jcoupling.append( (1, len(jn), j) )
elif len(jcoupling) == 1:
# Use specified coupling scheme
jcoupling = jcoupling[0]
else:
raise TypeError("CoupledSpinState only takes 3 or 4 arguments, got: %s" % (len(jcoupling) + 3) )
# Check arguments have correct form
if not (isinstance(jn, list) or isinstance(jn, tuple) or isinstance(jn, Tuple)):
raise TypeError('jn must be Tuple, list or tuple, got %s' %
jn.__class__.__name__)
if not (isinstance(jcoupling, list) or isinstance(jcoupling, tuple) or isinstance(jcoupling, Tuple)):
raise TypeError('jcoupling must be Tuple, list or tuple, got %s' %
jcoupling.__class__.__name__)
if not all(isinstance(term, list) or isinstance(term, tuple) or isinstance(term, Tuple) for term in jcoupling):
raise TypeError(
'All elements of jcoupling must be list, tuple or Tuple')
if not len(jn) - 1 == len(jcoupling):
raise ValueError('jcoupling must have length of %d, got %d' %
(len(jn) - 1, len(jcoupling)))
if not all(len(x) == 3 for x in jcoupling):
raise ValueError('All elements of jcoupling must have length 3')
# Build sympified args
j = sympify(j)
m = sympify(m)
jn = Tuple( *[sympify(ji) for ji in jn] )
jcoupling = Tuple( *[Tuple(sympify(
n1), sympify(n2), sympify(ji)) for (n1, n2, ji) in jcoupling] )
# Check values in coupling scheme give physical state
if any(2*ji != int(2*ji) for ji in jn if ji.is_number):
raise ValueError('All elements of jn must be integer or half-integer, got: %s' % jn)
if any(n1 != int(n1) or n2 != int(n2) for (n1, n2, _) in jcoupling):
raise ValueError('Indices in jcoupling must be integers')
if any(n1 < 1 or n2 < 1 or n1 > len(jn) or n2 > len(jn) for (n1, n2, _) in jcoupling):
raise ValueError('Indices must be between 1 and the number of coupled spin spaces')
if any(2*ji != int(2*ji) for (_, _, ji) in jcoupling if ji.is_number):
raise ValueError('All coupled j values in coupling scheme must be integer or half-integer')
coupled_n, coupled_jn = _build_coupled(jcoupling, len(jn))
jvals = list(jn)
for n, (n1, n2) in enumerate(coupled_n):
j1 = jvals[min(n1) - 1]
j2 = jvals[min(n2) - 1]
j3 = coupled_jn[n]
if sympify(j1).is_number and sympify(j2).is_number and sympify(j3).is_number:
if j1 + j2 < j3:
raise ValueError('All couplings must have j1+j2 >= j3, '
'in coupling number %d got j1,j2,j3: %d,%d,%d' % (n + 1, j1, j2, j3))
if abs(j1 - j2) > j3:
raise ValueError("All couplings must have |j1+j2| <= j3, "
"in coupling number %d got j1,j2,j3: %d,%d,%d" % (n + 1, j1, j2, j3))
if int(j1 + j2) == j1 + j2:
pass
jvals[min(n1 + n2) - 1] = j3
if len(jcoupling) > 0 and jcoupling[-1][2] != j:
raise ValueError('Last j value coupled together must be the final j of the state')
# Return state
return State.__new__(cls, j, m, jn, jcoupling)
def _print_label(self, printer, *args):
label = [printer._print(self.j), printer._print(self.m)]
for i, ji in enumerate(self.jn, start=1):
label.append('j%d=%s' % (
i, printer._print(ji)
))
for jn, (n1, n2) in zip(self.coupled_jn[:-1], self.coupled_n[:-1]):
label.append('j(%s)=%s' % (
','.join(str(i) for i in sorted(n1 + n2)), printer._print(jn)
))
return ','.join(label)
def _print_label_pretty(self, printer, *args):
label = [self.j, self.m]
for i, ji in enumerate(self.jn, start=1):
symb = 'j%d' % i
symb = pretty_symbol(symb)
symb = prettyForm(symb + '=')
item = prettyForm(*symb.right(printer._print(ji)))
label.append(item)
for jn, (n1, n2) in zip(self.coupled_jn[:-1], self.coupled_n[:-1]):
n = ','.join(pretty_symbol("j%d" % i)[-1] for i in sorted(n1 + n2))
symb = prettyForm('j' + n + '=')
item = prettyForm(*symb.right(printer._print(jn)))
label.append(item)
return self._print_sequence_pretty(
label, self._label_separator, printer, *args
)
def _print_label_latex(self, printer, *args):
label = [self.j, self.m]
for i, ji in enumerate(self.jn, start=1):
label.append('j_{%d}=%s' % (i, printer._print(ji)) )
for jn, (n1, n2) in zip(self.coupled_jn[:-1], self.coupled_n[:-1]):
n = ','.join(str(i) for i in sorted(n1 + n2))
label.append('j_{%s}=%s' % (n, printer._print(jn)) )
return self._print_sequence(
label, self._label_separator, printer, *args
)
@property
def jn(self):
return self.label[2]
@property
def coupling(self):
return self.label[3]
@property
def coupled_jn(self):
return _build_coupled(self.label[3], len(self.label[2]))[1]
@property
def coupled_n(self):
return _build_coupled(self.label[3], len(self.label[2]))[0]
@classmethod
def _eval_hilbert_space(cls, label):
j = Add(*label[2])
if j.is_number:
return DirectSumHilbertSpace(*[ ComplexSpace(x) for x in range(int(2*j + 1), 0, -2) ])
else:
# TODO: Need hilbert space fix, see issue 5732
# Desired behavior:
#ji = symbols('ji')
#ret = Sum(ComplexSpace(2*ji + 1), (ji, 0, j))
# Temporary fix:
return ComplexSpace(2*j + 1)
def _represent_coupled_base(self, **options):
evect = self.uncoupled_class()
if not self.j.is_number:
raise ValueError(
'State must not have symbolic j value to represent')
if not self.hilbert_space.dimension.is_number:
raise ValueError(
'State must not have symbolic j values to represent')
result = zeros(self.hilbert_space.dimension, 1)
if self.j == int(self.j):
start = self.j**2
else:
start = (2*self.j - 1)*(1 + 2*self.j)/4
result[start:start + 2*self.j + 1, 0] = evect(
self.j, self.m)._represent_base(**options)
return result
def _eval_rewrite_as_Jx(self, *args, **options):
if isinstance(self, Bra):
return self._rewrite_basis(Jx, JxBraCoupled, **options)
return self._rewrite_basis(Jx, JxKetCoupled, **options)
def _eval_rewrite_as_Jy(self, *args, **options):
if isinstance(self, Bra):
return self._rewrite_basis(Jy, JyBraCoupled, **options)
return self._rewrite_basis(Jy, JyKetCoupled, **options)
def _eval_rewrite_as_Jz(self, *args, **options):
if isinstance(self, Bra):
return self._rewrite_basis(Jz, JzBraCoupled, **options)
return self._rewrite_basis(Jz, JzKetCoupled, **options)
class JxKetCoupled(CoupledSpinState, Ket):
"""Coupled eigenket of Jx.
See JzKetCoupled for the usage of coupled spin eigenstates.
See Also
========
JzKetCoupled: Usage of coupled spin states
"""
@classmethod
def dual_class(self):
return JxBraCoupled
@classmethod
def uncoupled_class(self):
return JxKet
def _represent_default_basis(self, **options):
return self._represent_JzOp(None, **options)
def _represent_JxOp(self, basis, **options):
return self._represent_coupled_base(**options)
def _represent_JyOp(self, basis, **options):
return self._represent_coupled_base(alpha=3*pi/2, **options)
def _represent_JzOp(self, basis, **options):
return self._represent_coupled_base(beta=pi/2, **options)
class JxBraCoupled(CoupledSpinState, Bra):
"""Coupled eigenbra of Jx.
See JzKetCoupled for the usage of coupled spin eigenstates.
See Also
========
JzKetCoupled: Usage of coupled spin states
"""
@classmethod
def dual_class(self):
return JxKetCoupled
@classmethod
def uncoupled_class(self):
return JxBra
class JyKetCoupled(CoupledSpinState, Ket):
"""Coupled eigenket of Jy.
See JzKetCoupled for the usage of coupled spin eigenstates.
See Also
========
JzKetCoupled: Usage of coupled spin states
"""
@classmethod
def dual_class(self):
return JyBraCoupled
@classmethod
def uncoupled_class(self):
return JyKet
def _represent_default_basis(self, **options):
return self._represent_JzOp(None, **options)
def _represent_JxOp(self, basis, **options):
return self._represent_coupled_base(gamma=pi/2, **options)
def _represent_JyOp(self, basis, **options):
return self._represent_coupled_base(**options)
def _represent_JzOp(self, basis, **options):
return self._represent_coupled_base(alpha=3*pi/2, beta=-pi/2, gamma=pi/2, **options)
class JyBraCoupled(CoupledSpinState, Bra):
"""Coupled eigenbra of Jy.
See JzKetCoupled for the usage of coupled spin eigenstates.
See Also
========
JzKetCoupled: Usage of coupled spin states
"""
@classmethod
def dual_class(self):
return JyKetCoupled
@classmethod
def uncoupled_class(self):
return JyBra
class JzKetCoupled(CoupledSpinState, Ket):
r"""Coupled eigenket of Jz
Spin state that is an eigenket of Jz which represents the coupling of
separate spin spaces.
The arguments for creating instances of JzKetCoupled are ``j``, ``m``,
``jn`` and an optional ``jcoupling`` argument. The ``j`` and ``m`` options
are the total angular momentum quantum numbers, as used for normal states
(e.g. JzKet).
The other required parameter in ``jn``, which is a tuple defining the `j_n`
angular momentum quantum numbers of the product spaces. So for example, if
a state represented the coupling of the product basis state
`\left|j_1,m_1\right\rangle\times\left|j_2,m_2\right\rangle`, the ``jn``
for this state would be ``(j1,j2)``.
The final option is ``jcoupling``, which is used to define how the spaces
specified by ``jn`` are coupled, which includes both the order these spaces
are coupled together and the quantum numbers that arise from these
couplings. The ``jcoupling`` parameter itself is a list of lists, such that
each of the sublists defines a single coupling between the spin spaces. If
there are N coupled angular momentum spaces, that is ``jn`` has N elements,
then there must be N-1 sublists. Each of these sublists making up the
``jcoupling`` parameter have length 3. The first two elements are the
indices of the product spaces that are considered to be coupled together.
For example, if we want to couple `j_1` and `j_4`, the indices would be 1
and 4. If a state has already been coupled, it is referenced by the
smallest index that is coupled, so if `j_2` and `j_4` has already been
coupled to some `j_{24}`, then this value can be coupled by referencing it
with index 2. The final element of the sublist is the quantum number of the
coupled state. So putting everything together, into a valid sublist for
``jcoupling``, if `j_1` and `j_2` are coupled to an angular momentum space
with quantum number `j_{12}` with the value ``j12``, the sublist would be
``(1,2,j12)``, N-1 of these sublists are used in the list for
``jcoupling``.
Note the ``jcoupling`` parameter is optional, if it is not specified, the
default coupling is taken. This default value is to coupled the spaces in
order and take the quantum number of the coupling to be the maximum value.
For example, if the spin spaces are `j_1`, `j_2`, `j_3`, `j_4`, then the
default coupling couples `j_1` and `j_2` to `j_{12}=j_1+j_2`, then,
`j_{12}` and `j_3` are coupled to `j_{123}=j_{12}+j_3`, and finally
`j_{123}` and `j_4` to `j=j_{123}+j_4`. The jcoupling value that would
correspond to this is:
``((1,2,j1+j2),(1,3,j1+j2+j3))``
Parameters
==========
args : tuple
The arguments that must be passed are ``j``, ``m``, ``jn``, and
``jcoupling``. The ``j`` value is the total angular momentum. The ``m``
value is the eigenvalue of the Jz spin operator. The ``jn`` list are
the j values of argular momentum spaces coupled together. The
``jcoupling`` parameter is an optional parameter defining how the spaces
are coupled together. See the above description for how these coupling
parameters are defined.
Examples
========
Defining simple spin states, both numerical and symbolic:
>>> from sympy.physics.quantum.spin import JzKetCoupled
>>> from sympy import symbols
>>> JzKetCoupled(1, 0, (1, 1))
|1,0,j1=1,j2=1>
>>> j, m, j1, j2 = symbols('j m j1 j2')
>>> JzKetCoupled(j, m, (j1, j2))
|j,m,j1=j1,j2=j2>
Defining coupled spin states for more than 2 coupled spaces with various
coupling parameters:
>>> JzKetCoupled(2, 1, (1, 1, 1))
|2,1,j1=1,j2=1,j3=1,j(1,2)=2>
>>> JzKetCoupled(2, 1, (1, 1, 1), ((1,2,2),(1,3,2)) )
|2,1,j1=1,j2=1,j3=1,j(1,2)=2>
>>> JzKetCoupled(2, 1, (1, 1, 1), ((2,3,1),(1,2,2)) )
|2,1,j1=1,j2=1,j3=1,j(2,3)=1>
Rewriting the JzKetCoupled in terms of eigenkets of the Jx operator:
Note: that the resulting eigenstates are JxKetCoupled
>>> JzKetCoupled(1,1,(1,1)).rewrite("Jx")
|1,-1,j1=1,j2=1>/2 - sqrt(2)*|1,0,j1=1,j2=1>/2 + |1,1,j1=1,j2=1>/2
The rewrite method can be used to convert a coupled state to an uncoupled
state. This is done by passing coupled=False to the rewrite function:
>>> JzKetCoupled(1, 0, (1, 1)).rewrite('Jz', coupled=False)
-sqrt(2)*|1,-1>x|1,1>/2 + sqrt(2)*|1,1>x|1,-1>/2
Get the vector representation of a state in terms of the basis elements
of the Jx operator:
>>> from sympy.physics.quantum.represent import represent
>>> from sympy.physics.quantum.spin import Jx
>>> from sympy import S
>>> represent(JzKetCoupled(1,-1,(S(1)/2,S(1)/2)), basis=Jx)
Matrix([
[ 0],
[ 1/2],
[sqrt(2)/2],
[ 1/2]])
See Also
========
JzKet: Normal spin eigenstates
uncouple: Uncoupling of coupling spin states
couple: Coupling of uncoupled spin states
"""
@classmethod
def dual_class(self):
return JzBraCoupled
@classmethod
def uncoupled_class(self):
return JzKet
def _represent_default_basis(self, **options):
return self._represent_JzOp(None, **options)
def _represent_JxOp(self, basis, **options):
return self._represent_coupled_base(beta=3*pi/2, **options)
def _represent_JyOp(self, basis, **options):
return self._represent_coupled_base(alpha=3*pi/2, beta=pi/2, gamma=pi/2, **options)
def _represent_JzOp(self, basis, **options):
return self._represent_coupled_base(**options)
class JzBraCoupled(CoupledSpinState, Bra):
"""Coupled eigenbra of Jz.
See the JzKetCoupled for the usage of coupled spin eigenstates.
See Also
========
JzKetCoupled: Usage of coupled spin states
"""
@classmethod
def dual_class(self):
return JzKetCoupled
@classmethod
def uncoupled_class(self):
return JzBra
#-----------------------------------------------------------------------------
# Coupling/uncoupling
#-----------------------------------------------------------------------------
def couple(expr, jcoupling_list=None):
""" Couple a tensor product of spin states
This function can be used to couple an uncoupled tensor product of spin
states. All of the eigenstates to be coupled must be of the same class. It
will return a linear combination of eigenstates that are subclasses of
CoupledSpinState determined by Clebsch-Gordan angular momentum coupling
coefficients.
Parameters
==========
expr : Expr
An expression involving TensorProducts of spin states to be coupled.
Each state must be a subclass of SpinState and they all must be the
same class.
jcoupling_list : list or tuple
Elements of this list are sub-lists of length 2 specifying the order of
the coupling of the spin spaces. The length of this must be N-1, where N
is the number of states in the tensor product to be coupled. The
elements of this sublist are the same as the first two elements of each
sublist in the ``jcoupling`` parameter defined for JzKetCoupled. If this
parameter is not specified, the default value is taken, which couples
the first and second product basis spaces, then couples this new coupled
space to the third product space, etc
Examples
========
Couple a tensor product of numerical states for two spaces:
>>> from sympy.physics.quantum.spin import JzKet, couple
>>> from sympy.physics.quantum.tensorproduct import TensorProduct
>>> couple(TensorProduct(JzKet(1,0), JzKet(1,1)))
-sqrt(2)*|1,1,j1=1,j2=1>/2 + sqrt(2)*|2,1,j1=1,j2=1>/2
Numerical coupling of three spaces using the default coupling method, i.e.
first and second spaces couple, then this couples to the third space:
>>> couple(TensorProduct(JzKet(1,1), JzKet(1,1), JzKet(1,0)))
sqrt(6)*|2,2,j1=1,j2=1,j3=1,j(1,2)=2>/3 + sqrt(3)*|3,2,j1=1,j2=1,j3=1,j(1,2)=2>/3
Perform this same coupling, but we define the coupling to first couple
the first and third spaces:
>>> couple(TensorProduct(JzKet(1,1), JzKet(1,1), JzKet(1,0)), ((1,3),(1,2)) )
sqrt(2)*|2,2,j1=1,j2=1,j3=1,j(1,3)=1>/2 - sqrt(6)*|2,2,j1=1,j2=1,j3=1,j(1,3)=2>/6 + sqrt(3)*|3,2,j1=1,j2=1,j3=1,j(1,3)=2>/3
Couple a tensor product of symbolic states:
>>> from sympy import symbols
>>> j1,m1,j2,m2 = symbols('j1 m1 j2 m2')
>>> couple(TensorProduct(JzKet(j1,m1), JzKet(j2,m2)))
Sum(CG(j1, m1, j2, m2, j, m1 + m2)*|j,m1 + m2,j1=j1,j2=j2>, (j, m1 + m2, j1 + j2))
"""
a = expr.atoms(TensorProduct)
for tp in a:
# Allow other tensor products to be in expression
if not all([ isinstance(state, SpinState) for state in tp.args]):
continue
# If tensor product has all spin states, raise error for invalid tensor product state
if not all([state.__class__ is tp.args[0].__class__ for state in tp.args]):
raise TypeError('All states must be the same basis')
expr = expr.subs(tp, _couple(tp, jcoupling_list))
return expr
def _couple(tp, jcoupling_list):
states = tp.args
coupled_evect = states[0].coupled_class()
# Define default coupling if none is specified
if jcoupling_list is None:
jcoupling_list = []
for n in range(1, len(states)):
jcoupling_list.append( (1, n + 1) )
# Check jcoupling_list valid
if not len(jcoupling_list) == len(states) - 1:
raise TypeError('jcoupling_list must be length %d, got %d' %
(len(states) - 1, len(jcoupling_list)))
if not all( len(coupling) == 2 for coupling in jcoupling_list):
raise ValueError('Each coupling must define 2 spaces')
if any([n1 == n2 for n1, n2 in jcoupling_list]):
raise ValueError('Spin spaces cannot couple to themselves')
if all([sympify(n1).is_number and sympify(n2).is_number for n1, n2 in jcoupling_list]):
j_test = [0]*len(states)
for n1, n2 in jcoupling_list:
if j_test[n1 - 1] == -1 or j_test[n2 - 1] == -1:
raise ValueError('Spaces coupling j_n\'s are referenced by smallest n value')
j_test[max(n1, n2) - 1] = -1
# j values of states to be coupled together
jn = [state.j for state in states]
mn = [state.m for state in states]
# Create coupling_list, which defines all the couplings between all
# the spaces from jcoupling_list
coupling_list = []
n_list = [ [i + 1] for i in range(len(states)) ]
for j_coupling in jcoupling_list:
# Least n for all j_n which is coupled as first and second spaces
n1, n2 = j_coupling
# List of all n's coupled in first and second spaces
j1_n = list(n_list[n1 - 1])
j2_n = list(n_list[n2 - 1])
coupling_list.append( (j1_n, j2_n) )
# Set new j_n to be coupling of all j_n in both first and second spaces
n_list[ min(n1, n2) - 1 ] = sorted(j1_n + j2_n)
if all(state.j.is_number and state.m.is_number for state in states):
# Numerical coupling
# Iterate over difference between maximum possible j value of each coupling and the actual value
diff_max = [ Add( *[ jn[n - 1] - mn[n - 1] for n in coupling[0] +
coupling[1] ] ) for coupling in coupling_list ]
result = []
for diff in range(diff_max[-1] + 1):
# Determine available configurations
n = len(coupling_list)
tot = binomial(diff + n - 1, diff)
for config_num in range(tot):
diff_list = _confignum_to_difflist(config_num, diff, n)
# Skip the configuration if non-physical
# This is a lazy check for physical states given the loose restrictions of diff_max
if any( [ d > m for d, m in zip(diff_list, diff_max) ] ):
continue
# Determine term
cg_terms = []
coupled_j = list(jn)
jcoupling = []
for (j1_n, j2_n), coupling_diff in zip(coupling_list, diff_list):
j1 = coupled_j[ min(j1_n) - 1 ]
j2 = coupled_j[ min(j2_n) - 1 ]
j3 = j1 + j2 - coupling_diff
coupled_j[ min(j1_n + j2_n) - 1 ] = j3
m1 = Add( *[ mn[x - 1] for x in j1_n] )
m2 = Add( *[ mn[x - 1] for x in j2_n] )
m3 = m1 + m2
cg_terms.append( (j1, m1, j2, m2, j3, m3) )
jcoupling.append( (min(j1_n), min(j2_n), j3) )
# Better checks that state is physical
if any([ abs(term[5]) > term[4] for term in cg_terms ]):
continue
if any([ term[0] + term[2] < term[4] for term in cg_terms ]):
continue
if any([ abs(term[0] - term[2]) > term[4] for term in cg_terms ]):
continue
coeff = Mul( *[ CG(*term).doit() for term in cg_terms] )
state = coupled_evect(j3, m3, jn, jcoupling)
result.append(coeff*state)
return Add(*result)
else:
# Symbolic coupling
cg_terms = []
jcoupling = []
sum_terms = []
coupled_j = list(jn)
for j1_n, j2_n in coupling_list:
j1 = coupled_j[ min(j1_n) - 1 ]
j2 = coupled_j[ min(j2_n) - 1 ]
if len(j1_n + j2_n) == len(states):
j3 = symbols('j')
else:
j3_name = 'j' + ''.join(["%s" % n for n in j1_n + j2_n])
j3 = symbols(j3_name)
coupled_j[ min(j1_n + j2_n) - 1 ] = j3
m1 = Add( *[ mn[x - 1] for x in j1_n] )
m2 = Add( *[ mn[x - 1] for x in j2_n] )
m3 = m1 + m2
cg_terms.append( (j1, m1, j2, m2, j3, m3) )
jcoupling.append( (min(j1_n), min(j2_n), j3) )
sum_terms.append((j3, m3, j1 + j2))
coeff = Mul( *[ CG(*term) for term in cg_terms] )
state = coupled_evect(j3, m3, jn, jcoupling)
return Sum(coeff*state, *sum_terms)
def uncouple(expr, jn=None, jcoupling_list=None):
""" Uncouple a coupled spin state
Gives the uncoupled representation of a coupled spin state. Arguments must
be either a spin state that is a subclass of CoupledSpinState or a spin
state that is a subclass of SpinState and an array giving the j values
of the spaces that are to be coupled
Parameters
==========
expr : Expr
The expression containing states that are to be coupled. If the states
are a subclass of SpinState, the ``jn`` and ``jcoupling`` parameters
must be defined. If the states are a subclass of CoupledSpinState,
``jn`` and ``jcoupling`` will be taken from the state.
jn : list or tuple
The list of the j-values that are coupled. If state is a
CoupledSpinState, this parameter is ignored. This must be defined if
state is not a subclass of CoupledSpinState. The syntax of this
parameter is the same as the ``jn`` parameter of JzKetCoupled.
jcoupling_list : list or tuple
The list defining how the j-values are coupled together. If state is a
CoupledSpinState, this parameter is ignored. This must be defined if
state is not a subclass of CoupledSpinState. The syntax of this
parameter is the same as the ``jcoupling`` parameter of JzKetCoupled.
Examples
========
Uncouple a numerical state using a CoupledSpinState state:
>>> from sympy.physics.quantum.spin import JzKetCoupled, uncouple
>>> from sympy import S
>>> uncouple(JzKetCoupled(1, 0, (S(1)/2, S(1)/2)))
sqrt(2)*|1/2,-1/2>x|1/2,1/2>/2 + sqrt(2)*|1/2,1/2>x|1/2,-1/2>/2
Perform the same calculation using a SpinState state:
>>> from sympy.physics.quantum.spin import JzKet
>>> uncouple(JzKet(1, 0), (S(1)/2, S(1)/2))
sqrt(2)*|1/2,-1/2>x|1/2,1/2>/2 + sqrt(2)*|1/2,1/2>x|1/2,-1/2>/2
Uncouple a numerical state of three coupled spaces using a CoupledSpinState state:
>>> uncouple(JzKetCoupled(1, 1, (1, 1, 1), ((1,3,1),(1,2,1)) ))
|1,-1>x|1,1>x|1,1>/2 - |1,0>x|1,0>x|1,1>/2 + |1,1>x|1,0>x|1,0>/2 - |1,1>x|1,1>x|1,-1>/2
Perform the same calculation using a SpinState state:
>>> uncouple(JzKet(1, 1), (1, 1, 1), ((1,3,1),(1,2,1)) )
|1,-1>x|1,1>x|1,1>/2 - |1,0>x|1,0>x|1,1>/2 + |1,1>x|1,0>x|1,0>/2 - |1,1>x|1,1>x|1,-1>/2
Uncouple a symbolic state using a CoupledSpinState state:
>>> from sympy import symbols
>>> j,m,j1,j2 = symbols('j m j1 j2')
>>> uncouple(JzKetCoupled(j, m, (j1, j2)))
Sum(CG(j1, m1, j2, m2, j, m)*|j1,m1>x|j2,m2>, (m1, -j1, j1), (m2, -j2, j2))
Perform the same calculation using a SpinState state
>>> uncouple(JzKet(j, m), (j1, j2))
Sum(CG(j1, m1, j2, m2, j, m)*|j1,m1>x|j2,m2>, (m1, -j1, j1), (m2, -j2, j2))
"""
a = expr.atoms(SpinState)
for state in a:
expr = expr.subs(state, _uncouple(state, jn, jcoupling_list))
return expr
def _uncouple(state, jn, jcoupling_list):
if isinstance(state, CoupledSpinState):
jn = state.jn
coupled_n = state.coupled_n
coupled_jn = state.coupled_jn
evect = state.uncoupled_class()
elif isinstance(state, SpinState):
if jn is None:
raise ValueError("Must specify j-values for coupled state")
if not (isinstance(jn, list) or isinstance(jn, tuple)):
raise TypeError("jn must be list or tuple")
if jcoupling_list is None:
# Use default
jcoupling_list = []
for i in range(1, len(jn)):
jcoupling_list.append(
(1, 1 + i, Add(*[jn[j] for j in range(i + 1)])) )
if not (isinstance(jcoupling_list, list) or isinstance(jcoupling_list, tuple)):
raise TypeError("jcoupling must be a list or tuple")
if not len(jcoupling_list) == len(jn) - 1:
raise ValueError("Must specify 2 fewer coupling terms than the number of j values")
coupled_n, coupled_jn = _build_coupled(jcoupling_list, len(jn))
evect = state.__class__
else:
raise TypeError("state must be a spin state")
j = state.j
m = state.m
coupling_list = []
j_list = list(jn)
# Create coupling, which defines all the couplings between all the spaces
for j3, (n1, n2) in zip(coupled_jn, coupled_n):
# j's which are coupled as first and second spaces
j1 = j_list[n1[0] - 1]
j2 = j_list[n2[0] - 1]
# Build coupling list
coupling_list.append( (n1, n2, j1, j2, j3) )
# Set new value in j_list
j_list[min(n1 + n2) - 1] = j3
if j.is_number and m.is_number:
diff_max = [ 2*x for x in jn ]
diff = Add(*jn) - m
n = len(jn)
tot = binomial(diff + n - 1, diff)
result = []
for config_num in range(tot):
diff_list = _confignum_to_difflist(config_num, diff, n)
if any( [ d > p for d, p in zip(diff_list, diff_max) ] ):
continue
cg_terms = []
for coupling in coupling_list:
j1_n, j2_n, j1, j2, j3 = coupling
m1 = Add( *[ jn[x - 1] - diff_list[x - 1] for x in j1_n ] )
m2 = Add( *[ jn[x - 1] - diff_list[x - 1] for x in j2_n ] )
m3 = m1 + m2
cg_terms.append( (j1, m1, j2, m2, j3, m3) )
coeff = Mul( *[ CG(*term).doit() for term in cg_terms ] )
state = TensorProduct(
*[ evect(j, j - d) for j, d in zip(jn, diff_list) ] )
result.append(coeff*state)
return Add(*result)
else:
# Symbolic coupling
m_str = "m1:%d" % (len(jn) + 1)
mvals = symbols(m_str)
cg_terms = [(j1, Add(*[mvals[n - 1] for n in j1_n]),
j2, Add(*[mvals[n - 1] for n in j2_n]),
j3, Add(*[mvals[n - 1] for n in j1_n + j2_n])) for j1_n, j2_n, j1, j2, j3 in coupling_list[:-1] ]
cg_terms.append(*[(j1, Add(*[mvals[n - 1] for n in j1_n]),
j2, Add(*[mvals[n - 1] for n in j2_n]),
j, m) for j1_n, j2_n, j1, j2, j3 in [coupling_list[-1]] ])
cg_coeff = Mul(*[CG(*cg_term) for cg_term in cg_terms])
sum_terms = [ (m, -j, j) for j, m in zip(jn, mvals) ]
state = TensorProduct( *[ evect(j, m) for j, m in zip(jn, mvals) ] )
return Sum(cg_coeff*state, *sum_terms)
def _confignum_to_difflist(config_num, diff, list_len):
# Determines configuration of diffs into list_len number of slots
diff_list = []
for n in range(list_len):
prev_diff = diff
# Number of spots after current one
rem_spots = list_len - n - 1
# Number of configurations of distributing diff among the remaining spots
rem_configs = binomial(diff + rem_spots - 1, diff)
while config_num >= rem_configs:
config_num -= rem_configs
diff -= 1
rem_configs = binomial(diff + rem_spots - 1, diff)
diff_list.append(prev_diff - diff)
return diff_list
|
24b0325e972a7879aad1234c3b089eb8f3dd04e9bd4b046fc52e78aadd54e1ce
|
"""Matplotlib based plotting of quantum circuits.
Todo:
* Optimize printing of large circuits.
* Get this to work with single gates.
* Do a better job checking the form of circuits to make sure it is a Mul of
Gates.
* Get multi-target gates plotting.
* Get initial and final states to plot.
* Get measurements to plot. Might need to rethink measurement as a gate
issue.
* Get scale and figsize to be handled in a better way.
* Write some tests/examples!
"""
from __future__ import print_function, division
from sympy import Mul
from sympy.core.compatibility import range
from sympy.external import import_module
from sympy.physics.quantum.gate import Gate, OneQubitGate, CGate, CGateS
from sympy.core.core import BasicMeta
from sympy.core.assumptions import ManagedProperties
__all__ = [
'CircuitPlot',
'circuit_plot',
'labeller',
'Mz',
'Mx',
'CreateOneQubitGate',
'CreateCGate',
]
np = import_module('numpy')
matplotlib = import_module(
'matplotlib', __import__kwargs={'fromlist': ['pyplot']},
catch=(RuntimeError,)) # This is raised in environments that have no display.
if not np or not matplotlib:
class CircuitPlot(object):
def __init__(*args, **kwargs):
raise ImportError('numpy or matplotlib not available.')
def circuit_plot(*args, **kwargs):
raise ImportError('numpy or matplotlib not available.')
else:
pyplot = matplotlib.pyplot
Line2D = matplotlib.lines.Line2D
Circle = matplotlib.patches.Circle
#from matplotlib import rc
#rc('text',usetex=True)
class CircuitPlot(object):
"""A class for managing a circuit plot."""
scale = 1.0
fontsize = 20.0
linewidth = 1.0
control_radius = 0.05
not_radius = 0.15
swap_delta = 0.05
labels = []
inits = {}
label_buffer = 0.5
def __init__(self, c, nqubits, **kwargs):
self.circuit = c
self.ngates = len(self.circuit.args)
self.nqubits = nqubits
self.update(kwargs)
self._create_grid()
self._create_figure()
self._plot_wires()
self._plot_gates()
self._finish()
def update(self, kwargs):
"""Load the kwargs into the instance dict."""
self.__dict__.update(kwargs)
def _create_grid(self):
"""Create the grid of wires."""
scale = self.scale
wire_grid = np.arange(0.0, self.nqubits*scale, scale, dtype=float)
gate_grid = np.arange(0.0, self.ngates*scale, scale, dtype=float)
self._wire_grid = wire_grid
self._gate_grid = gate_grid
def _create_figure(self):
"""Create the main matplotlib figure."""
self._figure = pyplot.figure(
figsize=(self.ngates*self.scale, self.nqubits*self.scale),
facecolor='w',
edgecolor='w'
)
ax = self._figure.add_subplot(
1, 1, 1,
frameon=True
)
ax.set_axis_off()
offset = 0.5*self.scale
ax.set_xlim(self._gate_grid[0] - offset, self._gate_grid[-1] + offset)
ax.set_ylim(self._wire_grid[0] - offset, self._wire_grid[-1] + offset)
ax.set_aspect('equal')
self._axes = ax
def _plot_wires(self):
"""Plot the wires of the circuit diagram."""
xstart = self._gate_grid[0]
xstop = self._gate_grid[-1]
xdata = (xstart - self.scale, xstop + self.scale)
for i in range(self.nqubits):
ydata = (self._wire_grid[i], self._wire_grid[i])
line = Line2D(
xdata, ydata,
color='k',
lw=self.linewidth
)
self._axes.add_line(line)
if self.labels:
init_label_buffer = 0
if self.inits.get(self.labels[i]): init_label_buffer = 0.25
self._axes.text(
xdata[0]-self.label_buffer-init_label_buffer,ydata[0],
render_label(self.labels[i],self.inits),
size=self.fontsize,
color='k',ha='center',va='center')
self._plot_measured_wires()
def _plot_measured_wires(self):
ismeasured = self._measurements()
xstop = self._gate_grid[-1]
dy = 0.04 # amount to shift wires when doubled
# Plot doubled wires after they are measured
for im in ismeasured:
xdata = (self._gate_grid[ismeasured[im]],xstop+self.scale)
ydata = (self._wire_grid[im]+dy,self._wire_grid[im]+dy)
line = Line2D(
xdata, ydata,
color='k',
lw=self.linewidth
)
self._axes.add_line(line)
# Also double any controlled lines off these wires
for i,g in enumerate(self._gates()):
if isinstance(g, CGate) or isinstance(g, CGateS):
wires = g.controls + g.targets
for wire in wires:
if wire in ismeasured and \
self._gate_grid[i] > self._gate_grid[ismeasured[wire]]:
ydata = min(wires), max(wires)
xdata = self._gate_grid[i]-dy, self._gate_grid[i]-dy
line = Line2D(
xdata, ydata,
color='k',
lw=self.linewidth
)
self._axes.add_line(line)
def _gates(self):
"""Create a list of all gates in the circuit plot."""
gates = []
if isinstance(self.circuit, Mul):
for g in reversed(self.circuit.args):
if isinstance(g, Gate):
gates.append(g)
elif isinstance(self.circuit, Gate):
gates.append(self.circuit)
return gates
def _plot_gates(self):
"""Iterate through the gates and plot each of them."""
for i, gate in enumerate(self._gates()):
gate.plot_gate(self, i)
def _measurements(self):
"""Return a dict {i:j} where i is the index of the wire that has
been measured, and j is the gate where the wire is measured.
"""
ismeasured = {}
for i,g in enumerate(self._gates()):
if getattr(g,'measurement',False):
for target in g.targets:
if target in ismeasured:
if ismeasured[target] > i:
ismeasured[target] = i
else:
ismeasured[target] = i
return ismeasured
def _finish(self):
# Disable clipping to make panning work well for large circuits.
for o in self._figure.findobj():
o.set_clip_on(False)
def one_qubit_box(self, t, gate_idx, wire_idx):
"""Draw a box for a single qubit gate."""
x = self._gate_grid[gate_idx]
y = self._wire_grid[wire_idx]
self._axes.text(
x, y, t,
color='k',
ha='center',
va='center',
bbox=dict(ec='k', fc='w', fill=True, lw=self.linewidth),
size=self.fontsize
)
def two_qubit_box(self, t, gate_idx, wire_idx):
"""Draw a box for a two qubit gate. Doesn't work yet.
"""
x = self._gate_grid[gate_idx]
y = self._wire_grid[wire_idx]+0.5
print(self._gate_grid)
print(self._wire_grid)
obj = self._axes.text(
x, y, t,
color='k',
ha='center',
va='center',
bbox=dict(ec='k', fc='w', fill=True, lw=self.linewidth),
size=self.fontsize
)
def control_line(self, gate_idx, min_wire, max_wire):
"""Draw a vertical control line."""
xdata = (self._gate_grid[gate_idx], self._gate_grid[gate_idx])
ydata = (self._wire_grid[min_wire], self._wire_grid[max_wire])
line = Line2D(
xdata, ydata,
color='k',
lw=self.linewidth
)
self._axes.add_line(line)
def control_point(self, gate_idx, wire_idx):
"""Draw a control point."""
x = self._gate_grid[gate_idx]
y = self._wire_grid[wire_idx]
radius = self.control_radius
c = Circle(
(x, y),
radius*self.scale,
ec='k',
fc='k',
fill=True,
lw=self.linewidth
)
self._axes.add_patch(c)
def not_point(self, gate_idx, wire_idx):
"""Draw a NOT gates as the circle with plus in the middle."""
x = self._gate_grid[gate_idx]
y = self._wire_grid[wire_idx]
radius = self.not_radius
c = Circle(
(x, y),
radius,
ec='k',
fc='w',
fill=False,
lw=self.linewidth
)
self._axes.add_patch(c)
l = Line2D(
(x, x), (y - radius, y + radius),
color='k',
lw=self.linewidth
)
self._axes.add_line(l)
def swap_point(self, gate_idx, wire_idx):
"""Draw a swap point as a cross."""
x = self._gate_grid[gate_idx]
y = self._wire_grid[wire_idx]
d = self.swap_delta
l1 = Line2D(
(x - d, x + d),
(y - d, y + d),
color='k',
lw=self.linewidth
)
l2 = Line2D(
(x - d, x + d),
(y + d, y - d),
color='k',
lw=self.linewidth
)
self._axes.add_line(l1)
self._axes.add_line(l2)
def circuit_plot(c, nqubits, **kwargs):
"""Draw the circuit diagram for the circuit with nqubits.
Parameters
==========
c : circuit
The circuit to plot. Should be a product of Gate instances.
nqubits : int
The number of qubits to include in the circuit. Must be at least
as big as the largest `min_qubits`` of the gates.
"""
return CircuitPlot(c, nqubits, **kwargs)
def render_label(label, inits={}):
"""Slightly more flexible way to render labels.
>>> from sympy.physics.quantum.circuitplot import render_label
>>> render_label('q0')
'$\\\\left|q0\\\\right\\\\rangle$'
>>> render_label('q0', {'q0':'0'})
'$\\\\left|q0\\\\right\\\\rangle=\\\\left|0\\\\right\\\\rangle$'
"""
init = inits.get(label)
if init:
return r'$\left|%s\right\rangle=\left|%s\right\rangle$' % (label, init)
return r'$\left|%s\right\rangle$' % label
def labeller(n, symbol='q'):
"""Autogenerate labels for wires of quantum circuits.
Parameters
==========
n : int
number of qubits in the circuit
symbol : string
A character string to precede all gate labels. E.g. 'q_0', 'q_1', etc.
>>> from sympy.physics.quantum.circuitplot import labeller
>>> labeller(2)
['q_1', 'q_0']
>>> labeller(3,'j')
['j_2', 'j_1', 'j_0']
"""
return ['%s_%d' % (symbol,n-i-1) for i in range(n)]
class Mz(OneQubitGate):
"""Mock-up of a z measurement gate.
This is in circuitplot rather than gate.py because it's not a real
gate, it just draws one.
"""
measurement = True
gate_name='Mz'
gate_name_latex=u'M_z'
class Mx(OneQubitGate):
"""Mock-up of an x measurement gate.
This is in circuitplot rather than gate.py because it's not a real
gate, it just draws one.
"""
measurement = True
gate_name='Mx'
gate_name_latex=u'M_x'
class CreateOneQubitGate(ManagedProperties):
def __new__(mcl, name, latexname=None):
if not latexname:
latexname = name
return BasicMeta.__new__(mcl, name + "Gate", (OneQubitGate,),
{'gate_name': name, 'gate_name_latex': latexname})
def CreateCGate(name, latexname=None):
"""Use a lexical closure to make a controlled gate.
"""
if not latexname:
latexname = name
onequbitgate = CreateOneQubitGate(name, latexname)
def ControlledGate(ctrls,target):
return CGate(tuple(ctrls),onequbitgate(target))
return ControlledGate
|
68451b48c7cc3d4fa37e45e89892868791b990e3aec8144e77bee16ba770d9c7
|
#TODO:
# -Implement Clebsch-Gordan symmetries
# -Improve simplification method
# -Implement new simpifications
"""Clebsch-Gordon Coefficients."""
from __future__ import print_function, division
from sympy import (Add, expand, Eq, Expr, Mul, Piecewise, Pow, sqrt, Sum,
symbols, sympify, Wild)
from sympy.core.compatibility import range
from sympy.printing.pretty.stringpict import prettyForm, stringPict
from sympy.functions.special.tensor_functions import KroneckerDelta
from sympy.physics.wigner import clebsch_gordan, wigner_3j, wigner_6j, wigner_9j
__all__ = [
'CG',
'Wigner3j',
'Wigner6j',
'Wigner9j',
'cg_simp'
]
#-----------------------------------------------------------------------------
# CG Coefficients
#-----------------------------------------------------------------------------
class Wigner3j(Expr):
"""Class for the Wigner-3j symbols
Wigner 3j-symbols are coefficients determined by the coupling of
two angular momenta. When created, they are expressed as symbolic
quantities that, for numerical parameters, can be evaluated using the
``.doit()`` method [1]_.
Parameters
==========
j1, m1, j2, m2, j3, m3 : Number, Symbol
Terms determining the angular momentum of coupled angular momentum
systems.
Examples
========
Declare a Wigner-3j coefficient and calculate its value
>>> from sympy.physics.quantum.cg import Wigner3j
>>> w3j = Wigner3j(6,0,4,0,2,0)
>>> w3j
Wigner3j(6, 0, 4, 0, 2, 0)
>>> w3j.doit()
sqrt(715)/143
See Also
========
CG: Clebsch-Gordan coefficients
References
==========
.. [1] Varshalovich, D A, Quantum Theory of Angular Momentum. 1988.
"""
is_commutative = True
def __new__(cls, j1, m1, j2, m2, j3, m3):
args = map(sympify, (j1, m1, j2, m2, j3, m3))
return Expr.__new__(cls, *args)
@property
def j1(self):
return self.args[0]
@property
def m1(self):
return self.args[1]
@property
def j2(self):
return self.args[2]
@property
def m2(self):
return self.args[3]
@property
def j3(self):
return self.args[4]
@property
def m3(self):
return self.args[5]
@property
def is_symbolic(self):
return not all([arg.is_number for arg in self.args])
# This is modified from the _print_Matrix method
def _pretty(self, printer, *args):
m = ((printer._print(self.j1), printer._print(self.m1)),
(printer._print(self.j2), printer._print(self.m2)),
(printer._print(self.j3), printer._print(self.m3)))
hsep = 2
vsep = 1
maxw = [-1] * 3
for j in range(3):
maxw[j] = max([ m[j][i].width() for i in range(2) ])
D = None
for i in range(2):
D_row = None
for j in range(3):
s = m[j][i]
wdelta = maxw[j] - s.width()
wleft = wdelta //2
wright = wdelta - wleft
s = prettyForm(*s.right(' '*wright))
s = prettyForm(*s.left(' '*wleft))
if D_row is None:
D_row = s
continue
D_row = prettyForm(*D_row.right(' '*hsep))
D_row = prettyForm(*D_row.right(s))
if D is None:
D = D_row
continue
for _ in range(vsep):
D = prettyForm(*D.below(' '))
D = prettyForm(*D.below(D_row))
D = prettyForm(*D.parens())
return D
def _latex(self, printer, *args):
label = map(printer._print, (self.j1, self.j2, self.j3,
self.m1, self.m2, self.m3))
return r'\left(\begin{array}{ccc} %s & %s & %s \\ %s & %s & %s \end{array}\right)' % \
tuple(label)
def doit(self, **hints):
if self.is_symbolic:
raise ValueError("Coefficients must be numerical")
return wigner_3j(self.j1, self.j2, self.j3, self.m1, self.m2, self.m3)
class CG(Wigner3j):
r"""Class for Clebsch-Gordan coefficient
Clebsch-Gordan coefficients describe the angular momentum coupling between
two systems. The coefficients give the expansion of a coupled total angular
momentum state and an uncoupled tensor product state. The Clebsch-Gordan
coefficients are defined as [1]_:
.. math ::
C^{j_1,m_1}_{j_2,m_2,j_3,m_3} = \left\langle j_1,m_1;j_2,m_2 | j_3,m_3\right\rangle
Parameters
==========
j1, m1, j2, m2, j3, m3 : Number, Symbol
Terms determining the angular momentum of coupled angular momentum
systems.
Examples
========
Define a Clebsch-Gordan coefficient and evaluate its value
>>> from sympy.physics.quantum.cg import CG
>>> from sympy import S
>>> cg = CG(S(3)/2, S(3)/2, S(1)/2, -S(1)/2, 1, 1)
>>> cg
CG(3/2, 3/2, 1/2, -1/2, 1, 1)
>>> cg.doit()
sqrt(3)/2
See Also
========
Wigner3j: Wigner-3j symbols
References
==========
.. [1] Varshalovich, D A, Quantum Theory of Angular Momentum. 1988.
"""
def doit(self, **hints):
if self.is_symbolic:
raise ValueError("Coefficients must be numerical")
return clebsch_gordan(self.j1, self.j2, self.j3, self.m1, self.m2, self.m3)
def _pretty(self, printer, *args):
bot = printer._print_seq(
(self.j1, self.m1, self.j2, self.m2), delimiter=',')
top = printer._print_seq((self.j3, self.m3), delimiter=',')
pad = max(top.width(), bot.width())
bot = prettyForm(*bot.left(' '))
top = prettyForm(*top.left(' '))
if not pad == bot.width():
bot = prettyForm(*bot.right(' ' * (pad - bot.width())))
if not pad == top.width():
top = prettyForm(*top.right(' ' * (pad - top.width())))
s = stringPict('C' + ' '*pad)
s = prettyForm(*s.below(bot))
s = prettyForm(*s.above(top))
return s
def _latex(self, printer, *args):
label = map(printer._print, (self.j3, self.m3, self.j1,
self.m1, self.j2, self.m2))
return r'C^{%s,%s}_{%s,%s,%s,%s}' % tuple(label)
class Wigner6j(Expr):
"""Class for the Wigner-6j symbols
See Also
========
Wigner3j: Wigner-3j symbols
"""
def __new__(cls, j1, j2, j12, j3, j, j23):
args = map(sympify, (j1, j2, j12, j3, j, j23))
return Expr.__new__(cls, *args)
@property
def j1(self):
return self.args[0]
@property
def j2(self):
return self.args[1]
@property
def j12(self):
return self.args[2]
@property
def j3(self):
return self.args[3]
@property
def j(self):
return self.args[4]
@property
def j23(self):
return self.args[5]
@property
def is_symbolic(self):
return not all([arg.is_number for arg in self.args])
# This is modified from the _print_Matrix method
def _pretty(self, printer, *args):
m = ((printer._print(self.j1), printer._print(self.j3)),
(printer._print(self.j2), printer._print(self.j)),
(printer._print(self.j12), printer._print(self.j23)))
hsep = 2
vsep = 1
maxw = [-1] * 3
for j in range(3):
maxw[j] = max([ m[j][i].width() for i in range(2) ])
D = None
for i in range(2):
D_row = None
for j in range(3):
s = m[j][i]
wdelta = maxw[j] - s.width()
wleft = wdelta //2
wright = wdelta - wleft
s = prettyForm(*s.right(' '*wright))
s = prettyForm(*s.left(' '*wleft))
if D_row is None:
D_row = s
continue
D_row = prettyForm(*D_row.right(' '*hsep))
D_row = prettyForm(*D_row.right(s))
if D is None:
D = D_row
continue
for _ in range(vsep):
D = prettyForm(*D.below(' '))
D = prettyForm(*D.below(D_row))
D = prettyForm(*D.parens(left='{', right='}'))
return D
def _latex(self, printer, *args):
label = map(printer._print, (self.j1, self.j2, self.j12,
self.j3, self.j, self.j23))
return r'\left\{\begin{array}{ccc} %s & %s & %s \\ %s & %s & %s \end{array}\right\}' % \
tuple(label)
def doit(self, **hints):
if self.is_symbolic:
raise ValueError("Coefficients must be numerical")
return wigner_6j(self.j1, self.j2, self.j12, self.j3, self.j, self.j23)
class Wigner9j(Expr):
"""Class for the Wigner-9j symbols
See Also
========
Wigner3j: Wigner-3j symbols
"""
def __new__(cls, j1, j2, j12, j3, j4, j34, j13, j24, j):
args = map(sympify, (j1, j2, j12, j3, j4, j34, j13, j24, j))
return Expr.__new__(cls, *args)
@property
def j1(self):
return self.args[0]
@property
def j2(self):
return self.args[1]
@property
def j12(self):
return self.args[2]
@property
def j3(self):
return self.args[3]
@property
def j4(self):
return self.args[4]
@property
def j34(self):
return self.args[5]
@property
def j13(self):
return self.args[6]
@property
def j24(self):
return self.args[7]
@property
def j(self):
return self.args[8]
@property
def is_symbolic(self):
return not all([arg.is_number for arg in self.args])
# This is modified from the _print_Matrix method
def _pretty(self, printer, *args):
m = (
(printer._print(
self.j1), printer._print(self.j3), printer._print(self.j13)),
(printer._print(
self.j2), printer._print(self.j4), printer._print(self.j24)),
(printer._print(self.j12), printer._print(self.j34), printer._print(self.j)))
hsep = 2
vsep = 1
maxw = [-1] * 3
for j in range(3):
maxw[j] = max([ m[j][i].width() for i in range(3) ])
D = None
for i in range(3):
D_row = None
for j in range(3):
s = m[j][i]
wdelta = maxw[j] - s.width()
wleft = wdelta //2
wright = wdelta - wleft
s = prettyForm(*s.right(' '*wright))
s = prettyForm(*s.left(' '*wleft))
if D_row is None:
D_row = s
continue
D_row = prettyForm(*D_row.right(' '*hsep))
D_row = prettyForm(*D_row.right(s))
if D is None:
D = D_row
continue
for _ in range(vsep):
D = prettyForm(*D.below(' '))
D = prettyForm(*D.below(D_row))
D = prettyForm(*D.parens(left='{', right='}'))
return D
def _latex(self, printer, *args):
label = map(printer._print, (self.j1, self.j2, self.j12, self.j3,
self.j4, self.j34, self.j13, self.j24, self.j))
return r'\left\{\begin{array}{ccc} %s & %s & %s \\ %s & %s & %s \\ %s & %s & %s \end{array}\right\}' % \
tuple(label)
def doit(self, **hints):
if self.is_symbolic:
raise ValueError("Coefficients must be numerical")
return wigner_9j(self.j1, self.j2, self.j12, self.j3, self.j4, self.j34, self.j13, self.j24, self.j)
def cg_simp(e):
"""Simplify and combine CG coefficients
This function uses various symmetry and properties of sums and
products of Clebsch-Gordan coefficients to simplify statements
involving these terms [1]_.
Examples
========
Simplify the sum over CG(a,alpha,0,0,a,alpha) for all alpha to
2*a+1
>>> from sympy.physics.quantum.cg import CG, cg_simp
>>> a = CG(1,1,0,0,1,1)
>>> b = CG(1,0,0,0,1,0)
>>> c = CG(1,-1,0,0,1,-1)
>>> cg_simp(a+b+c)
3
See Also
========
CG: Clebsh-Gordan coefficients
References
==========
.. [1] Varshalovich, D A, Quantum Theory of Angular Momentum. 1988.
"""
if isinstance(e, Add):
return _cg_simp_add(e)
elif isinstance(e, Sum):
return _cg_simp_sum(e)
elif isinstance(e, Mul):
return Mul(*[cg_simp(arg) for arg in e.args])
elif isinstance(e, Pow):
return Pow(cg_simp(e.base), e.exp)
else:
return e
def _cg_simp_add(e):
#TODO: Improve simplification method
"""Takes a sum of terms involving Clebsch-Gordan coefficients and
simplifies the terms.
First, we create two lists, cg_part, which is all the terms involving CG
coefficients, and other_part, which is all other terms. The cg_part list
is then passed to the simplification methods, which return the new cg_part
and any additional terms that are added to other_part
"""
cg_part = []
other_part = []
e = expand(e)
for arg in e.args:
if arg.has(CG):
if isinstance(arg, Sum):
other_part.append(_cg_simp_sum(arg))
elif isinstance(arg, Mul):
terms = 1
for term in arg.args:
if isinstance(term, Sum):
terms *= _cg_simp_sum(term)
else:
terms *= term
if terms.has(CG):
cg_part.append(terms)
else:
other_part.append(terms)
else:
cg_part.append(arg)
else:
other_part.append(arg)
cg_part, other = _check_varsh_871_1(cg_part)
other_part.append(other)
cg_part, other = _check_varsh_871_2(cg_part)
other_part.append(other)
cg_part, other = _check_varsh_872_9(cg_part)
other_part.append(other)
return Add(*cg_part) + Add(*other_part)
def _check_varsh_871_1(term_list):
# Sum( CG(a,alpha,b,0,a,alpha), (alpha, -a, a)) == KroneckerDelta(b,0)
a, alpha, b, lt = map(Wild, ('a', 'alpha', 'b', 'lt'))
expr = lt*CG(a, alpha, b, 0, a, alpha)
simp = (2*a + 1)*KroneckerDelta(b, 0)
sign = lt/abs(lt)
build_expr = 2*a + 1
index_expr = a + alpha
return _check_cg_simp(expr, simp, sign, lt, term_list, (a, alpha, b, lt), (a, b), build_expr, index_expr)
def _check_varsh_871_2(term_list):
# Sum((-1)**(a-alpha)*CG(a,alpha,a,-alpha,c,0),(alpha,-a,a))
a, alpha, c, lt = map(Wild, ('a', 'alpha', 'c', 'lt'))
expr = lt*CG(a, alpha, a, -alpha, c, 0)
simp = sqrt(2*a + 1)*KroneckerDelta(c, 0)
sign = (-1)**(a - alpha)*lt/abs(lt)
build_expr = 2*a + 1
index_expr = a + alpha
return _check_cg_simp(expr, simp, sign, lt, term_list, (a, alpha, c, lt), (a, c), build_expr, index_expr)
def _check_varsh_872_9(term_list):
# Sum( CG(a,alpha,b,beta,c,gamma)*CG(a,alpha',b,beta',c,gamma), (gamma, -c, c), (c, abs(a-b), a+b))
a, alpha, alphap, b, beta, betap, c, gamma, lt = map(Wild, (
'a', 'alpha', 'alphap', 'b', 'beta', 'betap', 'c', 'gamma', 'lt'))
# Case alpha==alphap, beta==betap
# For numerical alpha,beta
expr = lt*CG(a, alpha, b, beta, c, gamma)**2
simp = 1
sign = lt/abs(lt)
x = abs(a - b)
y = abs(alpha + beta)
build_expr = a + b + 1 - Piecewise((x, x > y), (0, Eq(x, y)), (y, y > x))
index_expr = a + b - c
term_list, other1 = _check_cg_simp(expr, simp, sign, lt, term_list, (a, alpha, b, beta, c, gamma, lt), (a, alpha, b, beta), build_expr, index_expr)
# For symbolic alpha,beta
x = abs(a - b)
y = a + b
build_expr = (y + 1 - x)*(x + y + 1)
index_expr = (c - x)*(x + c) + c + gamma
term_list, other2 = _check_cg_simp(expr, simp, sign, lt, term_list, (a, alpha, b, beta, c, gamma, lt), (a, alpha, b, beta), build_expr, index_expr)
# Case alpha!=alphap or beta!=betap
# Note: this only works with leading term of 1, pattern matching is unable to match when there is a Wild leading term
# For numerical alpha,alphap,beta,betap
expr = CG(a, alpha, b, beta, c, gamma)*CG(a, alphap, b, betap, c, gamma)
simp = KroneckerDelta(alpha, alphap)*KroneckerDelta(beta, betap)
sign = sympify(1)
x = abs(a - b)
y = abs(alpha + beta)
build_expr = a + b + 1 - Piecewise((x, x > y), (0, Eq(x, y)), (y, y > x))
index_expr = a + b - c
term_list, other3 = _check_cg_simp(expr, simp, sign, sympify(1), term_list, (a, alpha, alphap, b, beta, betap, c, gamma), (a, alpha, alphap, b, beta, betap), build_expr, index_expr)
# For symbolic alpha,alphap,beta,betap
x = abs(a - b)
y = a + b
build_expr = (y + 1 - x)*(x + y + 1)
index_expr = (c - x)*(x + c) + c + gamma
term_list, other4 = _check_cg_simp(expr, simp, sign, sympify(1), term_list, (a, alpha, alphap, b, beta, betap, c, gamma), (a, alpha, alphap, b, beta, betap), build_expr, index_expr)
return term_list, other1 + other2 + other4
def _check_cg_simp(expr, simp, sign, lt, term_list, variables, dep_variables, build_index_expr, index_expr):
""" Checks for simplifications that can be made, returning a tuple of the
simplified list of terms and any terms generated by simplification.
Parameters
==========
expr: expression
The expression with Wild terms that will be matched to the terms in
the sum
simp: expression
The expression with Wild terms that is substituted in place of the CG
terms in the case of simplification
sign: expression
The expression with Wild terms denoting the sign that is on expr that
must match
lt: expression
The expression with Wild terms that gives the leading term of the
matched expr
term_list: list
A list of all of the terms is the sum to be simplified
variables: list
A list of all the variables that appears in expr
dep_variables: list
A list of the variables that must match for all the terms in the sum,
i.e. the dependent variables
build_index_expr: expression
Expression with Wild terms giving the number of elements in cg_index
index_expr: expression
Expression with Wild terms giving the index terms have when storing
them to cg_index
"""
other_part = 0
i = 0
while i < len(term_list):
sub_1 = _check_cg(term_list[i], expr, len(variables))
if sub_1 is None:
i += 1
continue
if not sympify(build_index_expr.subs(sub_1)).is_number:
i += 1
continue
sub_dep = [(x, sub_1[x]) for x in dep_variables]
cg_index = [None] * build_index_expr.subs(sub_1)
for j in range(i, len(term_list)):
sub_2 = _check_cg(term_list[j], expr.subs(sub_dep), len(variables) - len(dep_variables), sign=(sign.subs(sub_1), sign.subs(sub_dep)))
if sub_2 is None:
continue
if not sympify(index_expr.subs(sub_dep).subs(sub_2)).is_number:
continue
cg_index[index_expr.subs(sub_dep).subs(sub_2)] = j, expr.subs(lt, 1).subs(sub_dep).subs(sub_2), lt.subs(sub_2), sign.subs(sub_dep).subs(sub_2)
if all(i is not None for i in cg_index):
min_lt = min(*[ abs(term[2]) for term in cg_index ])
indices = [ term[0] for term in cg_index]
indices.sort()
indices.reverse()
[ term_list.pop(j) for j in indices ]
for term in cg_index:
if abs(term[2]) > min_lt:
term_list.append( (term[2] - min_lt*term[3]) * term[1] )
other_part += min_lt * (sign*simp).subs(sub_1)
else:
i += 1
return term_list, other_part
def _check_cg(cg_term, expr, length, sign=None):
"""Checks whether a term matches the given expression"""
# TODO: Check for symmetries
matches = cg_term.match(expr)
if matches is None:
return
if sign is not None:
if not isinstance(sign, tuple):
raise TypeError('sign must be a tuple')
if not sign[0] == (sign[1]).subs(matches):
return
if len(matches) == length:
return matches
def _cg_simp_sum(e):
e = _check_varsh_sum_871_1(e)
e = _check_varsh_sum_871_2(e)
e = _check_varsh_sum_872_4(e)
return e
def _check_varsh_sum_871_1(e):
a = Wild('a')
alpha = symbols('alpha')
b = Wild('b')
match = e.match(Sum(CG(a, alpha, b, 0, a, alpha), (alpha, -a, a)))
if match is not None and len(match) == 2:
return ((2*a + 1)*KroneckerDelta(b, 0)).subs(match)
return e
def _check_varsh_sum_871_2(e):
a = Wild('a')
alpha = symbols('alpha')
c = Wild('c')
match = e.match(
Sum((-1)**(a - alpha)*CG(a, alpha, a, -alpha, c, 0), (alpha, -a, a)))
if match is not None and len(match) == 2:
return (sqrt(2*a + 1)*KroneckerDelta(c, 0)).subs(match)
return e
def _check_varsh_sum_872_4(e):
a = Wild('a')
alpha = Wild('alpha')
b = Wild('b')
beta = Wild('beta')
c = Wild('c')
cp = Wild('cp')
gamma = Wild('gamma')
gammap = Wild('gammap')
match1 = e.match(Sum(CG(a, alpha, b, beta, c, gamma)*CG(
a, alpha, b, beta, cp, gammap), (alpha, -a, a), (beta, -b, b)))
if match1 is not None and len(match1) == 8:
return (KroneckerDelta(c, cp)*KroneckerDelta(gamma, gammap)).subs(match1)
match2 = e.match(Sum(
CG(a, alpha, b, beta, c, gamma)**2, (alpha, -a, a), (beta, -b, b)))
if match2 is not None and len(match2) == 6:
return 1
return e
def _cg_list(term):
if isinstance(term, CG):
return (term,), 1, 1
cg = []
coeff = 1
if not (isinstance(term, Mul) or isinstance(term, Pow)):
raise NotImplementedError('term must be CG, Add, Mul or Pow')
if isinstance(term, Pow) and sympify(term.exp).is_number:
if sympify(term.exp).is_number:
[ cg.append(term.base) for _ in range(term.exp) ]
else:
return (term,), 1, 1
if isinstance(term, Mul):
for arg in term.args:
if isinstance(arg, CG):
cg.append(arg)
else:
coeff *= arg
return cg, coeff, coeff/abs(coeff)
|
084bc1ed7d9c067dbbef29e75320b69d4ed5311875ea92877c83e29b2b5d15ff
|
from sympy.physics.quantum.circuitplot import labeller, render_label, Mz, CreateOneQubitGate,\
CreateCGate
from sympy.physics.quantum.gate import CNOT, H, SWAP, CGate, S, T
from sympy.external import import_module
from sympy.utilities.pytest import skip
mpl = import_module('matplotlib')
def test_render_label():
assert render_label('q0') == r'$\left|q0\right\rangle$'
assert render_label('q0', {'q0': '0'}) == r'$\left|q0\right\rangle=\left|0\right\rangle$'
def test_Mz():
assert str(Mz(0)) == 'Mz(0)'
def test_create1():
Qgate = CreateOneQubitGate('Q')
assert str(Qgate(0)) == 'Q(0)'
def test_createc():
Qgate = CreateCGate('Q')
assert str(Qgate([1],0)) == 'C((1),Q(0))'
def test_labeller():
"""Test the labeller utility"""
assert labeller(2) == ['q_1', 'q_0']
assert labeller(3,'j') == ['j_2', 'j_1', 'j_0']
def test_cnot():
"""Test a simple cnot circuit. Right now this only makes sure the code doesn't
raise an exception, and some simple properties
"""
if not mpl:
skip("matplotlib not installed")
else:
from sympy.physics.quantum.circuitplot import CircuitPlot
c = CircuitPlot(CNOT(1,0),2,labels=labeller(2))
assert c.ngates == 2
assert c.nqubits == 2
assert c.labels == ['q_1', 'q_0']
c = CircuitPlot(CNOT(1,0),2)
assert c.ngates == 2
assert c.nqubits == 2
assert c.labels == []
def test_ex1():
if not mpl:
skip("matplotlib not installed")
else:
from sympy.physics.quantum.circuitplot import CircuitPlot
c = CircuitPlot(CNOT(1,0)*H(1),2,labels=labeller(2))
assert c.ngates == 2
assert c.nqubits == 2
assert c.labels == ['q_1', 'q_0']
def test_ex4():
if not mpl:
skip("matplotlib not installed")
else:
from sympy.physics.quantum.circuitplot import CircuitPlot
c = CircuitPlot(SWAP(0,2)*H(0)* CGate((0,),S(1)) *H(1)*CGate((0,),T(2))\
*CGate((1,),S(2))*H(2),3,labels=labeller(3,'j'))
assert c.ngates == 7
assert c.nqubits == 3
assert c.labels == ['j_2', 'j_1', 'j_0']
|
c01a5aa95e27c25bc37fd5b14d130a7c2f09b7be7d6a2b46c4787c54da040d6e
|
# -*- encoding: utf-8 -*-
"""
TODO:
* Address Issue 2251, printing of spin states
"""
from sympy.physics.quantum.anticommutator import AntiCommutator
from sympy.physics.quantum.cg import CG, Wigner3j, Wigner6j, Wigner9j
from sympy.physics.quantum.commutator import Commutator
from sympy.physics.quantum.constants import hbar
from sympy.physics.quantum.dagger import Dagger
from sympy.physics.quantum.gate import CGate, CNotGate, IdentityGate, UGate, XGate
from sympy.physics.quantum.hilbert import ComplexSpace, FockSpace, HilbertSpace, L2
from sympy.physics.quantum.innerproduct import InnerProduct
from sympy.physics.quantum.operator import Operator, OuterProduct, DifferentialOperator
from sympy.physics.quantum.qexpr import QExpr
from sympy.physics.quantum.qubit import Qubit, IntQubit
from sympy.physics.quantum.spin import Jz, J2, JzBra, JzBraCoupled, JzKet, JzKetCoupled, Rotation, WignerD
from sympy.physics.quantum.state import Bra, Ket, TimeDepBra, TimeDepKet
from sympy.physics.quantum.tensorproduct import TensorProduct
from sympy.physics.quantum.sho1d import RaisingOp
from sympy import Derivative, Function, Interval, Matrix, Pow, S, symbols, Symbol, oo
from sympy.core.compatibility import exec_
from sympy.utilities.pytest import XFAIL
# Imports used in srepr strings
from sympy.physics.quantum.constants import HBar
from sympy.physics.quantum.hilbert import DirectSumHilbertSpace, TensorProductHilbertSpace, TensorPowerHilbertSpace
from sympy.physics.quantum.spin import JzOp, J2Op
from sympy import Add, Integer, Mul, Rational, Tuple, true, false
from sympy.printing import srepr
from sympy.printing.pretty import pretty as xpretty
from sympy.printing.latex import latex
from sympy.core.compatibility import u_decode as u
MutableDenseMatrix = Matrix
ENV = {}
exec_("from sympy import *", ENV)
def sT(expr, string):
"""
sT := sreprTest
from sympy/printing/tests/test_repr.py
"""
assert srepr(expr) == string
assert eval(string) == expr
def pretty(expr):
"""ASCII pretty-printing"""
return xpretty(expr, use_unicode=False, wrap_line=False)
def upretty(expr):
"""Unicode pretty-printing"""
return xpretty(expr, use_unicode=True, wrap_line=False)
def test_anticommutator():
A = Operator('A')
B = Operator('B')
ac = AntiCommutator(A, B)
ac_tall = AntiCommutator(A**2, B)
assert str(ac) == '{A,B}'
assert pretty(ac) == '{A,B}'
assert upretty(ac) == u'{A,B}'
assert latex(ac) == r'\left\{A,B\right\}'
sT(ac, "AntiCommutator(Operator(Symbol('A')),Operator(Symbol('B')))")
assert str(ac_tall) == '{A**2,B}'
ascii_str = \
"""\
/ 2 \\\n\
<A ,B>\n\
\\ /\
"""
ucode_str = \
u("""\
⎧ 2 ⎫\n\
⎨A ,B⎬\n\
⎩ ⎭\
""")
assert pretty(ac_tall) == ascii_str
assert upretty(ac_tall) == ucode_str
assert latex(ac_tall) == r'\left\{A^{2},B\right\}'
sT(ac_tall, "AntiCommutator(Pow(Operator(Symbol('A')), Integer(2)),Operator(Symbol('B')))")
def test_cg():
cg = CG(1, 2, 3, 4, 5, 6)
wigner3j = Wigner3j(1, 2, 3, 4, 5, 6)
wigner6j = Wigner6j(1, 2, 3, 4, 5, 6)
wigner9j = Wigner9j(1, 2, 3, 4, 5, 6, 7, 8, 9)
assert str(cg) == 'CG(1, 2, 3, 4, 5, 6)'
ascii_str = \
"""\
5,6 \n\
C \n\
1,2,3,4\
"""
ucode_str = \
u("""\
5,6 \n\
C \n\
1,2,3,4\
""")
assert pretty(cg) == ascii_str
assert upretty(cg) == ucode_str
assert latex(cg) == r'C^{5,6}_{1,2,3,4}'
sT(cg, "CG(Integer(1), Integer(2), Integer(3), Integer(4), Integer(5), Integer(6))")
assert str(wigner3j) == 'Wigner3j(1, 2, 3, 4, 5, 6)'
ascii_str = \
"""\
/1 3 5\\\n\
| |\n\
\\2 4 6/\
"""
ucode_str = \
u("""\
⎛1 3 5⎞\n\
⎜ ⎟\n\
⎝2 4 6⎠\
""")
assert pretty(wigner3j) == ascii_str
assert upretty(wigner3j) == ucode_str
assert latex(wigner3j) == \
r'\left(\begin{array}{ccc} 1 & 3 & 5 \\ 2 & 4 & 6 \end{array}\right)'
sT(wigner3j, "Wigner3j(Integer(1), Integer(2), Integer(3), Integer(4), Integer(5), Integer(6))")
assert str(wigner6j) == 'Wigner6j(1, 2, 3, 4, 5, 6)'
ascii_str = \
"""\
/1 2 3\\\n\
< >\n\
\\4 5 6/\
"""
ucode_str = \
u("""\
⎧1 2 3⎫\n\
⎨ ⎬\n\
⎩4 5 6⎭\
""")
assert pretty(wigner6j) == ascii_str
assert upretty(wigner6j) == ucode_str
assert latex(wigner6j) == \
r'\left\{\begin{array}{ccc} 1 & 2 & 3 \\ 4 & 5 & 6 \end{array}\right\}'
sT(wigner6j, "Wigner6j(Integer(1), Integer(2), Integer(3), Integer(4), Integer(5), Integer(6))")
assert str(wigner9j) == 'Wigner9j(1, 2, 3, 4, 5, 6, 7, 8, 9)'
ascii_str = \
"""\
/1 2 3\\\n\
| |\n\
<4 5 6>\n\
| |\n\
\\7 8 9/\
"""
ucode_str = \
u("""\
⎧1 2 3⎫\n\
⎪ ⎪\n\
⎨4 5 6⎬\n\
⎪ ⎪\n\
⎩7 8 9⎭\
""")
assert pretty(wigner9j) == ascii_str
assert upretty(wigner9j) == ucode_str
assert latex(wigner9j) == \
r'\left\{\begin{array}{ccc} 1 & 2 & 3 \\ 4 & 5 & 6 \\ 7 & 8 & 9 \end{array}\right\}'
sT(wigner9j, "Wigner9j(Integer(1), Integer(2), Integer(3), Integer(4), Integer(5), Integer(6), Integer(7), Integer(8), Integer(9))")
def test_commutator():
A = Operator('A')
B = Operator('B')
c = Commutator(A, B)
c_tall = Commutator(A**2, B)
assert str(c) == '[A,B]'
assert pretty(c) == '[A,B]'
assert upretty(c) == u'[A,B]'
assert latex(c) == r'\left[A,B\right]'
sT(c, "Commutator(Operator(Symbol('A')),Operator(Symbol('B')))")
assert str(c_tall) == '[A**2,B]'
ascii_str = \
"""\
[ 2 ]\n\
[A ,B]\
"""
ucode_str = \
u("""\
⎡ 2 ⎤\n\
⎣A ,B⎦\
""")
assert pretty(c_tall) == ascii_str
assert upretty(c_tall) == ucode_str
assert latex(c_tall) == r'\left[A^{2},B\right]'
sT(c_tall, "Commutator(Pow(Operator(Symbol('A')), Integer(2)),Operator(Symbol('B')))")
def test_constants():
assert str(hbar) == 'hbar'
assert pretty(hbar) == 'hbar'
assert upretty(hbar) == u'ℏ'
assert latex(hbar) == r'\hbar'
sT(hbar, "HBar()")
def test_dagger():
x = symbols('x')
expr = Dagger(x)
assert str(expr) == 'Dagger(x)'
ascii_str = \
"""\
+\n\
x \
"""
ucode_str = \
u("""\
†\n\
x \
""")
assert pretty(expr) == ascii_str
assert upretty(expr) == ucode_str
assert latex(expr) == r'x^{\dagger}'
sT(expr, "Dagger(Symbol('x'))")
@XFAIL
def test_gate_failing():
a, b, c, d = symbols('a,b,c,d')
uMat = Matrix([[a, b], [c, d]])
g = UGate((0,), uMat)
assert str(g) == 'U(0)'
def test_gate():
a, b, c, d = symbols('a,b,c,d')
uMat = Matrix([[a, b], [c, d]])
q = Qubit(1, 0, 1, 0, 1)
g1 = IdentityGate(2)
g2 = CGate((3, 0), XGate(1))
g3 = CNotGate(1, 0)
g4 = UGate((0,), uMat)
assert str(g1) == '1(2)'
assert pretty(g1) == '1 \n 2'
assert upretty(g1) == u'1 \n 2'
assert latex(g1) == r'1_{2}'
sT(g1, "IdentityGate(Integer(2))")
assert str(g1*q) == '1(2)*|10101>'
ascii_str = \
"""\
1 *|10101>\n\
2 \
"""
ucode_str = \
u("""\
1 ⋅❘10101⟩\n\
2 \
""")
assert pretty(g1*q) == ascii_str
assert upretty(g1*q) == ucode_str
assert latex(g1*q) == r'1_{2} {\left|10101\right\rangle }'
sT(g1*q, "Mul(IdentityGate(Integer(2)), Qubit(Integer(1),Integer(0),Integer(1),Integer(0),Integer(1)))")
assert str(g2) == 'C((3,0),X(1))'
ascii_str = \
"""\
C /X \\\n\
3,0\\ 1/\
"""
ucode_str = \
u("""\
C ⎛X ⎞\n\
3,0⎝ 1⎠\
""")
assert pretty(g2) == ascii_str
assert upretty(g2) == ucode_str
assert latex(g2) == r'C_{3,0}{\left(X_{1}\right)}'
sT(g2, "CGate(Tuple(Integer(3), Integer(0)),XGate(Integer(1)))")
assert str(g3) == 'CNOT(1,0)'
ascii_str = \
"""\
CNOT \n\
1,0\
"""
ucode_str = \
u("""\
CNOT \n\
1,0\
""")
assert pretty(g3) == ascii_str
assert upretty(g3) == ucode_str
assert latex(g3) == r'CNOT_{1,0}'
sT(g3, "CNotGate(Integer(1),Integer(0))")
ascii_str = \
"""\
U \n\
0\
"""
ucode_str = \
u("""\
U \n\
0\
""")
assert str(g4) == \
"""\
U((0,),Matrix([\n\
[a, b],\n\
[c, d]]))\
"""
assert pretty(g4) == ascii_str
assert upretty(g4) == ucode_str
assert latex(g4) == r'U_{0}'
sT(g4, "UGate(Tuple(Integer(0)),MutableDenseMatrix([[Symbol('a'), Symbol('b')], [Symbol('c'), Symbol('d')]]))")
def test_hilbert():
h1 = HilbertSpace()
h2 = ComplexSpace(2)
h3 = FockSpace()
h4 = L2(Interval(0, oo))
assert str(h1) == 'H'
assert pretty(h1) == 'H'
assert upretty(h1) == u'H'
assert latex(h1) == r'\mathcal{H}'
sT(h1, "HilbertSpace()")
assert str(h2) == 'C(2)'
ascii_str = \
"""\
2\n\
C \
"""
ucode_str = \
u("""\
2\n\
C \
""")
assert pretty(h2) == ascii_str
assert upretty(h2) == ucode_str
assert latex(h2) == r'\mathcal{C}^{2}'
sT(h2, "ComplexSpace(Integer(2))")
assert str(h3) == 'F'
assert pretty(h3) == 'F'
assert upretty(h3) == u'F'
assert latex(h3) == r'\mathcal{F}'
sT(h3, "FockSpace()")
assert str(h4) == 'L2(Interval(0, oo))'
ascii_str = \
"""\
2\n\
L \
"""
ucode_str = \
u("""\
2\n\
L \
""")
assert pretty(h4) == ascii_str
assert upretty(h4) == ucode_str
assert latex(h4) == r'{\mathcal{L}^2}\left( \left[0, \infty\right) \right)'
sT(h4, "L2(Interval(Integer(0), oo, false, true))")
assert str(h1 + h2) == 'H+C(2)'
ascii_str = \
"""\
2\n\
H + C \
"""
ucode_str = \
u("""\
2\n\
H ⊕ C \
""")
assert pretty(h1 + h2) == ascii_str
assert upretty(h1 + h2) == ucode_str
assert latex(h1 + h2)
sT(h1 + h2, "DirectSumHilbertSpace(HilbertSpace(),ComplexSpace(Integer(2)))")
assert str(h1*h2) == "H*C(2)"
ascii_str = \
"""\
2\n\
H x C \
"""
ucode_str = \
u("""\
2\n\
H ⨂ C \
""")
assert pretty(h1*h2) == ascii_str
assert upretty(h1*h2) == ucode_str
assert latex(h1*h2)
sT(h1*h2,
"TensorProductHilbertSpace(HilbertSpace(),ComplexSpace(Integer(2)))")
assert str(h1**2) == 'H**2'
ascii_str = \
"""\
x2\n\
H \
"""
ucode_str = \
u("""\
⨂2\n\
H \
""")
assert pretty(h1**2) == ascii_str
assert upretty(h1**2) == ucode_str
assert latex(h1**2) == r'{\mathcal{H}}^{\otimes 2}'
sT(h1**2, "TensorPowerHilbertSpace(HilbertSpace(),Integer(2))")
def test_innerproduct():
x = symbols('x')
ip1 = InnerProduct(Bra(), Ket())
ip2 = InnerProduct(TimeDepBra(), TimeDepKet())
ip3 = InnerProduct(JzBra(1, 1), JzKet(1, 1))
ip4 = InnerProduct(JzBraCoupled(1, 1, (1, 1)), JzKetCoupled(1, 1, (1, 1)))
ip_tall1 = InnerProduct(Bra(x/2), Ket(x/2))
ip_tall2 = InnerProduct(Bra(x), Ket(x/2))
ip_tall3 = InnerProduct(Bra(x/2), Ket(x))
assert str(ip1) == '<psi|psi>'
assert pretty(ip1) == '<psi|psi>'
assert upretty(ip1) == u'⟨ψ❘ψ⟩'
assert latex(
ip1) == r'\left\langle \psi \right. {\left|\psi\right\rangle }'
sT(ip1, "InnerProduct(Bra(Symbol('psi')),Ket(Symbol('psi')))")
assert str(ip2) == '<psi;t|psi;t>'
assert pretty(ip2) == '<psi;t|psi;t>'
assert upretty(ip2) == u'⟨ψ;t❘ψ;t⟩'
assert latex(ip2) == \
r'\left\langle \psi;t \right. {\left|\psi;t\right\rangle }'
sT(ip2, "InnerProduct(TimeDepBra(Symbol('psi'),Symbol('t')),TimeDepKet(Symbol('psi'),Symbol('t')))")
assert str(ip3) == "<1,1|1,1>"
assert pretty(ip3) == '<1,1|1,1>'
assert upretty(ip3) == u'⟨1,1❘1,1⟩'
assert latex(ip3) == r'\left\langle 1,1 \right. {\left|1,1\right\rangle }'
sT(ip3, "InnerProduct(JzBra(Integer(1),Integer(1)),JzKet(Integer(1),Integer(1)))")
assert str(ip4) == "<1,1,j1=1,j2=1|1,1,j1=1,j2=1>"
assert pretty(ip4) == '<1,1,j1=1,j2=1|1,1,j1=1,j2=1>'
assert upretty(ip4) == u'⟨1,1,j₁=1,j₂=1❘1,1,j₁=1,j₂=1⟩'
assert latex(ip4) == \
r'\left\langle 1,1,j_{1}=1,j_{2}=1 \right. {\left|1,1,j_{1}=1,j_{2}=1\right\rangle }'
sT(ip4, "InnerProduct(JzBraCoupled(Integer(1),Integer(1),Tuple(Integer(1), Integer(1)),Tuple(Tuple(Integer(1), Integer(2), Integer(1)))),JzKetCoupled(Integer(1),Integer(1),Tuple(Integer(1), Integer(1)),Tuple(Tuple(Integer(1), Integer(2), Integer(1)))))")
assert str(ip_tall1) == '<x/2|x/2>'
ascii_str = \
"""\
/ | \\ \n\
/ x|x \\\n\
\\ -|- /\n\
\\2|2/ \
"""
ucode_str = \
u("""\
╱ │ ╲ \n\
╱ x│x ╲\n\
╲ ─│─ ╱\n\
╲2│2╱ \
""")
assert pretty(ip_tall1) == ascii_str
assert upretty(ip_tall1) == ucode_str
assert latex(ip_tall1) == \
r'\left\langle \frac{x}{2} \right. {\left|\frac{x}{2}\right\rangle }'
sT(ip_tall1, "InnerProduct(Bra(Mul(Rational(1, 2), Symbol('x'))),Ket(Mul(Rational(1, 2), Symbol('x'))))")
assert str(ip_tall2) == '<x|x/2>'
ascii_str = \
"""\
/ | \\ \n\
/ |x \\\n\
\\ x|- /\n\
\\ |2/ \
"""
ucode_str = \
u("""\
╱ │ ╲ \n\
╱ │x ╲\n\
╲ x│─ ╱\n\
╲ │2╱ \
""")
assert pretty(ip_tall2) == ascii_str
assert upretty(ip_tall2) == ucode_str
assert latex(ip_tall2) == \
r'\left\langle x \right. {\left|\frac{x}{2}\right\rangle }'
sT(ip_tall2,
"InnerProduct(Bra(Symbol('x')),Ket(Mul(Rational(1, 2), Symbol('x'))))")
assert str(ip_tall3) == '<x/2|x>'
ascii_str = \
"""\
/ | \\ \n\
/ x| \\\n\
\\ -|x /\n\
\\2| / \
"""
ucode_str = \
u("""\
╱ │ ╲ \n\
╱ x│ ╲\n\
╲ ─│x ╱\n\
╲2│ ╱ \
""")
assert pretty(ip_tall3) == ascii_str
assert upretty(ip_tall3) == ucode_str
assert latex(ip_tall3) == \
r'\left\langle \frac{x}{2} \right. {\left|x\right\rangle }'
sT(ip_tall3,
"InnerProduct(Bra(Mul(Rational(1, 2), Symbol('x'))),Ket(Symbol('x')))")
def test_operator():
a = Operator('A')
b = Operator('B', Symbol('t'), S(1)/2)
inv = a.inv()
f = Function('f')
x = symbols('x')
d = DifferentialOperator(Derivative(f(x), x), f(x))
op = OuterProduct(Ket(), Bra())
assert str(a) == 'A'
assert pretty(a) == 'A'
assert upretty(a) == u'A'
assert latex(a) == 'A'
sT(a, "Operator(Symbol('A'))")
assert str(inv) == 'A**(-1)'
ascii_str = \
"""\
-1\n\
A \
"""
ucode_str = \
u("""\
-1\n\
A \
""")
assert pretty(inv) == ascii_str
assert upretty(inv) == ucode_str
assert latex(inv) == r'A^{-1}'
sT(inv, "Pow(Operator(Symbol('A')), Integer(-1))")
assert str(d) == 'DifferentialOperator(Derivative(f(x), x),f(x))'
ascii_str = \
"""\
/d \\\n\
DifferentialOperator|--(f(x)),f(x)|\n\
\\dx /\
"""
ucode_str = \
u("""\
⎛d ⎞\n\
DifferentialOperator⎜──(f(x)),f(x)⎟\n\
⎝dx ⎠\
""")
assert pretty(d) == ascii_str
assert upretty(d) == ucode_str
assert latex(d) == \
r'DifferentialOperator\left(\frac{d}{d x} f{\left(x \right)},f{\left(x \right)}\right)'
sT(d, "DifferentialOperator(Derivative(Function('f')(Symbol('x')), Tuple(Symbol('x'), Integer(1))),Function('f')(Symbol('x')))")
assert str(b) == 'Operator(B,t,1/2)'
assert pretty(b) == 'Operator(B,t,1/2)'
assert upretty(b) == u'Operator(B,t,1/2)'
assert latex(b) == r'Operator\left(B,t,\frac{1}{2}\right)'
sT(b, "Operator(Symbol('B'),Symbol('t'),Rational(1, 2))")
assert str(op) == '|psi><psi|'
assert pretty(op) == '|psi><psi|'
assert upretty(op) == u'❘ψ⟩⟨ψ❘'
assert latex(op) == r'{\left|\psi\right\rangle }{\left\langle \psi\right|}'
sT(op, "OuterProduct(Ket(Symbol('psi')),Bra(Symbol('psi')))")
def test_qexpr():
q = QExpr('q')
assert str(q) == 'q'
assert pretty(q) == 'q'
assert upretty(q) == u'q'
assert latex(q) == r'q'
sT(q, "QExpr(Symbol('q'))")
def test_qubit():
q1 = Qubit('0101')
q2 = IntQubit(8)
assert str(q1) == '|0101>'
assert pretty(q1) == '|0101>'
assert upretty(q1) == u'❘0101⟩'
assert latex(q1) == r'{\left|0101\right\rangle }'
sT(q1, "Qubit(Integer(0),Integer(1),Integer(0),Integer(1))")
assert str(q2) == '|8>'
assert pretty(q2) == '|8>'
assert upretty(q2) == u'❘8⟩'
assert latex(q2) == r'{\left|8\right\rangle }'
sT(q2, "IntQubit(8)")
def test_spin():
lz = JzOp('L')
ket = JzKet(1, 0)
bra = JzBra(1, 0)
cket = JzKetCoupled(1, 0, (1, 2))
cbra = JzBraCoupled(1, 0, (1, 2))
cket_big = JzKetCoupled(1, 0, (1, 2, 3))
cbra_big = JzBraCoupled(1, 0, (1, 2, 3))
rot = Rotation(1, 2, 3)
bigd = WignerD(1, 2, 3, 4, 5, 6)
smalld = WignerD(1, 2, 3, 0, 4, 0)
assert str(lz) == 'Lz'
ascii_str = \
"""\
L \n\
z\
"""
ucode_str = \
u("""\
L \n\
z\
""")
assert pretty(lz) == ascii_str
assert upretty(lz) == ucode_str
assert latex(lz) == 'L_z'
sT(lz, "JzOp(Symbol('L'))")
assert str(J2) == 'J2'
ascii_str = \
"""\
2\n\
J \
"""
ucode_str = \
u("""\
2\n\
J \
""")
assert pretty(J2) == ascii_str
assert upretty(J2) == ucode_str
assert latex(J2) == r'J^2'
sT(J2, "J2Op(Symbol('J'))")
assert str(Jz) == 'Jz'
ascii_str = \
"""\
J \n\
z\
"""
ucode_str = \
u("""\
J \n\
z\
""")
assert pretty(Jz) == ascii_str
assert upretty(Jz) == ucode_str
assert latex(Jz) == 'J_z'
sT(Jz, "JzOp(Symbol('J'))")
assert str(ket) == '|1,0>'
assert pretty(ket) == '|1,0>'
assert upretty(ket) == u'❘1,0⟩'
assert latex(ket) == r'{\left|1,0\right\rangle }'
sT(ket, "JzKet(Integer(1),Integer(0))")
assert str(bra) == '<1,0|'
assert pretty(bra) == '<1,0|'
assert upretty(bra) == u'⟨1,0❘'
assert latex(bra) == r'{\left\langle 1,0\right|}'
sT(bra, "JzBra(Integer(1),Integer(0))")
assert str(cket) == '|1,0,j1=1,j2=2>'
assert pretty(cket) == '|1,0,j1=1,j2=2>'
assert upretty(cket) == u'❘1,0,j₁=1,j₂=2⟩'
assert latex(cket) == r'{\left|1,0,j_{1}=1,j_{2}=2\right\rangle }'
sT(cket, "JzKetCoupled(Integer(1),Integer(0),Tuple(Integer(1), Integer(2)),Tuple(Tuple(Integer(1), Integer(2), Integer(1))))")
assert str(cbra) == '<1,0,j1=1,j2=2|'
assert pretty(cbra) == '<1,0,j1=1,j2=2|'
assert upretty(cbra) == u'⟨1,0,j₁=1,j₂=2❘'
assert latex(cbra) == r'{\left\langle 1,0,j_{1}=1,j_{2}=2\right|}'
sT(cbra, "JzBraCoupled(Integer(1),Integer(0),Tuple(Integer(1), Integer(2)),Tuple(Tuple(Integer(1), Integer(2), Integer(1))))")
assert str(cket_big) == '|1,0,j1=1,j2=2,j3=3,j(1,2)=3>'
# TODO: Fix non-unicode pretty printing
# i.e. j1,2 -> j(1,2)
assert pretty(cket_big) == '|1,0,j1=1,j2=2,j3=3,j1,2=3>'
assert upretty(cket_big) == u'❘1,0,j₁=1,j₂=2,j₃=3,j₁,₂=3⟩'
assert latex(cket_big) == \
r'{\left|1,0,j_{1}=1,j_{2}=2,j_{3}=3,j_{1,2}=3\right\rangle }'
sT(cket_big, "JzKetCoupled(Integer(1),Integer(0),Tuple(Integer(1), Integer(2), Integer(3)),Tuple(Tuple(Integer(1), Integer(2), Integer(3)), Tuple(Integer(1), Integer(3), Integer(1))))")
assert str(cbra_big) == '<1,0,j1=1,j2=2,j3=3,j(1,2)=3|'
assert pretty(cbra_big) == u'<1,0,j1=1,j2=2,j3=3,j1,2=3|'
assert upretty(cbra_big) == u'⟨1,0,j₁=1,j₂=2,j₃=3,j₁,₂=3❘'
assert latex(cbra_big) == \
r'{\left\langle 1,0,j_{1}=1,j_{2}=2,j_{3}=3,j_{1,2}=3\right|}'
sT(cbra_big, "JzBraCoupled(Integer(1),Integer(0),Tuple(Integer(1), Integer(2), Integer(3)),Tuple(Tuple(Integer(1), Integer(2), Integer(3)), Tuple(Integer(1), Integer(3), Integer(1))))")
assert str(rot) == 'R(1,2,3)'
assert pretty(rot) == 'R (1,2,3)'
assert upretty(rot) == u'ℛ (1,2,3)'
assert latex(rot) == r'\mathcal{R}\left(1,2,3\right)'
sT(rot, "Rotation(Integer(1),Integer(2),Integer(3))")
assert str(bigd) == 'WignerD(1, 2, 3, 4, 5, 6)'
ascii_str = \
"""\
1 \n\
D (4,5,6)\n\
2,3 \
"""
ucode_str = \
u("""\
1 \n\
D (4,5,6)\n\
2,3 \
""")
assert pretty(bigd) == ascii_str
assert upretty(bigd) == ucode_str
assert latex(bigd) == r'D^{1}_{2,3}\left(4,5,6\right)'
sT(bigd, "WignerD(Integer(1), Integer(2), Integer(3), Integer(4), Integer(5), Integer(6))")
assert str(smalld) == 'WignerD(1, 2, 3, 0, 4, 0)'
ascii_str = \
"""\
1 \n\
d (4)\n\
2,3 \
"""
ucode_str = \
u("""\
1 \n\
d (4)\n\
2,3 \
""")
assert pretty(smalld) == ascii_str
assert upretty(smalld) == ucode_str
assert latex(smalld) == r'd^{1}_{2,3}\left(4\right)'
sT(smalld, "WignerD(Integer(1), Integer(2), Integer(3), Integer(0), Integer(4), Integer(0))")
def test_state():
x = symbols('x')
bra = Bra()
ket = Ket()
bra_tall = Bra(x/2)
ket_tall = Ket(x/2)
tbra = TimeDepBra()
tket = TimeDepKet()
assert str(bra) == '<psi|'
assert pretty(bra) == '<psi|'
assert upretty(bra) == u'⟨ψ❘'
assert latex(bra) == r'{\left\langle \psi\right|}'
sT(bra, "Bra(Symbol('psi'))")
assert str(ket) == '|psi>'
assert pretty(ket) == '|psi>'
assert upretty(ket) == u'❘ψ⟩'
assert latex(ket) == r'{\left|\psi\right\rangle }'
sT(ket, "Ket(Symbol('psi'))")
assert str(bra_tall) == '<x/2|'
ascii_str = \
"""\
/ |\n\
/ x|\n\
\\ -|\n\
\\2|\
"""
ucode_str = \
u("""\
╱ │\n\
╱ x│\n\
╲ ─│\n\
╲2│\
""")
assert pretty(bra_tall) == ascii_str
assert upretty(bra_tall) == ucode_str
assert latex(bra_tall) == r'{\left\langle \frac{x}{2}\right|}'
sT(bra_tall, "Bra(Mul(Rational(1, 2), Symbol('x')))")
assert str(ket_tall) == '|x/2>'
ascii_str = \
"""\
| \\ \n\
|x \\\n\
|- /\n\
|2/ \
"""
ucode_str = \
u("""\
│ ╲ \n\
│x ╲\n\
│─ ╱\n\
│2╱ \
""")
assert pretty(ket_tall) == ascii_str
assert upretty(ket_tall) == ucode_str
assert latex(ket_tall) == r'{\left|\frac{x}{2}\right\rangle }'
sT(ket_tall, "Ket(Mul(Rational(1, 2), Symbol('x')))")
assert str(tbra) == '<psi;t|'
assert pretty(tbra) == u'<psi;t|'
assert upretty(tbra) == u'⟨ψ;t❘'
assert latex(tbra) == r'{\left\langle \psi;t\right|}'
sT(tbra, "TimeDepBra(Symbol('psi'),Symbol('t'))")
assert str(tket) == '|psi;t>'
assert pretty(tket) == '|psi;t>'
assert upretty(tket) == u'❘ψ;t⟩'
assert latex(tket) == r'{\left|\psi;t\right\rangle }'
sT(tket, "TimeDepKet(Symbol('psi'),Symbol('t'))")
def test_tensorproduct():
tp = TensorProduct(JzKet(1, 1), JzKet(1, 0))
assert str(tp) == '|1,1>x|1,0>'
assert pretty(tp) == '|1,1>x |1,0>'
assert upretty(tp) == u'❘1,1⟩⨂ ❘1,0⟩'
assert latex(tp) == \
r'{{\left|1,1\right\rangle }}\otimes {{\left|1,0\right\rangle }}'
sT(tp, "TensorProduct(JzKet(Integer(1),Integer(1)), JzKet(Integer(1),Integer(0)))")
def test_big_expr():
f = Function('f')
x = symbols('x')
e1 = Dagger(AntiCommutator(Operator('A') + Operator('B'), Pow(DifferentialOperator(Derivative(f(x), x), f(x)), 3))*TensorProduct(Jz**2, Operator('A') + Operator('B')))*(JzBra(1, 0) + JzBra(1, 1))*(JzKet(0, 0) + JzKet(1, -1))
e2 = Commutator(Jz**2, Operator('A') + Operator('B'))*AntiCommutator(Dagger(Operator('C')*Operator('D')), Operator('E').inv()**2)*Dagger(Commutator(Jz, J2))
e3 = Wigner3j(1, 2, 3, 4, 5, 6)*TensorProduct(Commutator(Operator('A') + Dagger(Operator('B')), Operator('C') + Operator('D')), Jz - J2)*Dagger(OuterProduct(Dagger(JzBra(1, 1)), JzBra(1, 0)))*TensorProduct(JzKetCoupled(1, 1, (1, 1)) + JzKetCoupled(1, 0, (1, 1)), JzKetCoupled(1, -1, (1, 1)))
e4 = (ComplexSpace(1)*ComplexSpace(2) + FockSpace()**2)*(L2(Interval(
0, oo)) + HilbertSpace())
assert str(e1) == '(Jz**2)x(Dagger(A) + Dagger(B))*{Dagger(DifferentialOperator(Derivative(f(x), x),f(x)))**3,Dagger(A) + Dagger(B)}*(<1,0| + <1,1|)*(|0,0> + |1,-1>)'
ascii_str = \
"""\
/ 3 \\ \n\
|/ +\\ | \n\
2 / + +\\ <| /d \\ | + +> \n\
/J \\ x \\A + B /*||DifferentialOperator|--(f(x)),f(x)| | ,A + B |*(<1,0| + <1,1|)*(|0,0> + |1,-1>)\n\
\\ z/ \\\\ \\dx / / / \
"""
ucode_str = \
u("""\
⎧ 3 ⎫ \n\
⎪⎛ †⎞ ⎪ \n\
2 ⎛ † †⎞ ⎨⎜ ⎛d ⎞ ⎟ † †⎬ \n\
⎛J ⎞ ⨂ ⎝A + B ⎠⋅⎪⎜DifferentialOperator⎜──(f(x)),f(x)⎟ ⎟ ,A + B ⎪⋅(⟨1,0❘ + ⟨1,1❘)⋅(❘0,0⟩ + ❘1,-1⟩)\n\
⎝ z⎠ ⎩⎝ ⎝dx ⎠ ⎠ ⎭ \
""")
assert pretty(e1) == ascii_str
assert upretty(e1) == ucode_str
assert latex(e1) == \
r'{J_z^{2}}\otimes \left({A^{\dagger} + B^{\dagger}}\right) \left\{\left(DifferentialOperator\left(\frac{d}{d x} f{\left(x \right)},f{\left(x \right)}\right)^{\dagger}\right)^{3},A^{\dagger} + B^{\dagger}\right\} \left({\left\langle 1,0\right|} + {\left\langle 1,1\right|}\right) \left({\left|0,0\right\rangle } + {\left|1,-1\right\rangle }\right)'
sT(e1, "Mul(TensorProduct(Pow(JzOp(Symbol('J')), Integer(2)), Add(Dagger(Operator(Symbol('A'))), Dagger(Operator(Symbol('B'))))), AntiCommutator(Pow(Dagger(DifferentialOperator(Derivative(Function('f')(Symbol('x')), Tuple(Symbol('x'), Integer(1))),Function('f')(Symbol('x')))), Integer(3)),Add(Dagger(Operator(Symbol('A'))), Dagger(Operator(Symbol('B'))))), Add(JzBra(Integer(1),Integer(0)), JzBra(Integer(1),Integer(1))), Add(JzKet(Integer(0),Integer(0)), JzKet(Integer(1),Integer(-1))))")
assert str(e2) == '[Jz**2,A + B]*{E**(-2),Dagger(D)*Dagger(C)}*[J2,Jz]'
ascii_str = \
"""\
[ 2 ] / -2 + +\\ [ 2 ]\n\
[/J \\ ,A + B]*<E ,D *C >*[J ,J ]\n\
[\\ z/ ] \\ / [ z]\
"""
ucode_str = \
u("""\
⎡ 2 ⎤ ⎧ -2 † †⎫ ⎡ 2 ⎤\n\
⎢⎛J ⎞ ,A + B⎥⋅⎨E ,D ⋅C ⎬⋅⎢J ,J ⎥\n\
⎣⎝ z⎠ ⎦ ⎩ ⎭ ⎣ z⎦\
""")
assert pretty(e2) == ascii_str
assert upretty(e2) == ucode_str
assert latex(e2) == \
r'\left[J_z^{2},A + B\right] \left\{E^{-2},D^{\dagger} C^{\dagger}\right\} \left[J^2,J_z\right]'
sT(e2, "Mul(Commutator(Pow(JzOp(Symbol('J')), Integer(2)),Add(Operator(Symbol('A')), Operator(Symbol('B')))), AntiCommutator(Pow(Operator(Symbol('E')), Integer(-2)),Mul(Dagger(Operator(Symbol('D'))), Dagger(Operator(Symbol('C'))))), Commutator(J2Op(Symbol('J')),JzOp(Symbol('J'))))")
assert str(e3) == \
"Wigner3j(1, 2, 3, 4, 5, 6)*[Dagger(B) + A,C + D]x(-J2 + Jz)*|1,0><1,1|*(|1,0,j1=1,j2=1> + |1,1,j1=1,j2=1>)x|1,-1,j1=1,j2=1>"
ascii_str = \
"""\
[ + ] / 2 \\ \n\
/1 3 5\\*[B + A,C + D]x |- J + J |*|1,0><1,1|*(|1,0,j1=1,j2=1> + |1,1,j1=1,j2=1>)x |1,-1,j1=1,j2=1>\n\
| | \\ z/ \n\
\\2 4 6/ \
"""
ucode_str = \
u("""\
⎡ † ⎤ ⎛ 2 ⎞ \n\
⎛1 3 5⎞⋅⎣B + A,C + D⎦⨂ ⎜- J + J ⎟⋅❘1,0⟩⟨1,1❘⋅(❘1,0,j₁=1,j₂=1⟩ + ❘1,1,j₁=1,j₂=1⟩)⨂ ❘1,-1,j₁=1,j₂=1⟩\n\
⎜ ⎟ ⎝ z⎠ \n\
⎝2 4 6⎠ \
""")
assert pretty(e3) == ascii_str
assert upretty(e3) == ucode_str
assert latex(e3) == \
r'\left(\begin{array}{ccc} 1 & 3 & 5 \\ 2 & 4 & 6 \end{array}\right) {\left[B^{\dagger} + A,C + D\right]}\otimes \left({- J^2 + J_z}\right) {\left|1,0\right\rangle }{\left\langle 1,1\right|} \left({{\left|1,0,j_{1}=1,j_{2}=1\right\rangle } + {\left|1,1,j_{1}=1,j_{2}=1\right\rangle }}\right)\otimes {{\left|1,-1,j_{1}=1,j_{2}=1\right\rangle }}'
sT(e3, "Mul(Wigner3j(Integer(1), Integer(2), Integer(3), Integer(4), Integer(5), Integer(6)), TensorProduct(Commutator(Add(Dagger(Operator(Symbol('B'))), Operator(Symbol('A'))),Add(Operator(Symbol('C')), Operator(Symbol('D')))), Add(Mul(Integer(-1), J2Op(Symbol('J'))), JzOp(Symbol('J')))), OuterProduct(JzKet(Integer(1),Integer(0)),JzBra(Integer(1),Integer(1))), TensorProduct(Add(JzKetCoupled(Integer(1),Integer(0),Tuple(Integer(1), Integer(1)),Tuple(Tuple(Integer(1), Integer(2), Integer(1)))), JzKetCoupled(Integer(1),Integer(1),Tuple(Integer(1), Integer(1)),Tuple(Tuple(Integer(1), Integer(2), Integer(1))))), JzKetCoupled(Integer(1),Integer(-1),Tuple(Integer(1), Integer(1)),Tuple(Tuple(Integer(1), Integer(2), Integer(1))))))")
assert str(e4) == '(C(1)*C(2)+F**2)*(L2(Interval(0, oo))+H)'
ascii_str = \
"""\
// 1 2\\ x2\\ / 2 \\\n\
\\\\C x C / + F / x \\L + H/\
"""
ucode_str = \
u("""\
⎛⎛ 1 2⎞ ⨂2⎞ ⎛ 2 ⎞\n\
⎝⎝C ⨂ C ⎠ ⊕ F ⎠ ⨂ ⎝L ⊕ H⎠\
""")
assert pretty(e4) == ascii_str
assert upretty(e4) == ucode_str
assert latex(e4) == \
r'\left(\left(\mathcal{C}^{1}\otimes \mathcal{C}^{2}\right)\oplus {\mathcal{F}}^{\otimes 2}\right)\otimes \left({\mathcal{L}^2}\left( \left[0, \infty\right) \right)\oplus \mathcal{H}\right)'
sT(e4, "TensorProductHilbertSpace((DirectSumHilbertSpace(TensorProductHilbertSpace(ComplexSpace(Integer(1)),ComplexSpace(Integer(2))),TensorPowerHilbertSpace(FockSpace(),Integer(2)))),(DirectSumHilbertSpace(L2(Interval(Integer(0), oo, false, true)),HilbertSpace())))")
def _test_sho1d():
ad = RaisingOp('a')
assert pretty(ad) == u' \N{DAGGER}\na '
assert latex(ad) == 'a^{\\dagger}'
|
356f449d5753c02ab907cd9818d7bc44f7ff481ca9edd6ac5e10fdebda4b67b4
|
# -*- coding: utf-8 -*-
from sympy import symbols, sin, cos, sqrt, Function
from sympy.core.compatibility import u_decode as u
from sympy.physics.vector import ReferenceFrame, dynamicsymbols
from sympy.physics.vector.printing import (VectorLatexPrinter, vpprint)
# TODO : Figure out how to make the pretty printing tests readable like the
# ones in sympy.printing.pretty.tests.test_printing.
a, b, c = symbols('a, b, c')
alpha, omega, beta = dynamicsymbols('alpha, omega, beta')
A = ReferenceFrame('A')
N = ReferenceFrame('N')
v = a ** 2 * N.x + b * N.y + c * sin(alpha) * N.z
w = alpha * N.x + sin(omega) * N.y + alpha * beta * N.z
o = a/b * N.x + (c+b)/a * N.y + c**2/b * N.z
y = a ** 2 * (N.x | N.y) + b * (N.y | N.y) + c * sin(alpha) * (N.z | N.y)
x = alpha * (N.x | N.x) + sin(omega) * (N.y | N.z) + alpha * beta * (N.z | N.x)
def ascii_vpretty(expr):
return vpprint(expr, use_unicode=False, wrap_line=False)
def unicode_vpretty(expr):
return vpprint(expr, use_unicode=True, wrap_line=False)
def test_latex_printer():
r = Function('r')('t')
assert VectorLatexPrinter().doprint(r ** 2) == "r^{2}"
def test_vector_pretty_print():
# TODO : The unit vectors should print with subscripts but they just
# print as `n_x` instead of making `x` a subscript with unicode.
# TODO : The pretty print division does not print correctly here:
# w = alpha * N.x + sin(omega) * N.y + alpha / beta * N.z
expected = """\
2
a n_x + b n_y + c*sin(alpha) n_z\
"""
uexpected = u("""\
2
a n_x + b n_y + c⋅sin(α) n_z\
""")
assert ascii_vpretty(v) == expected
assert unicode_vpretty(v) == uexpected
expected = u('alpha n_x + sin(omega) n_y + alpha*beta n_z')
uexpected = u('α n_x + sin(ω) n_y + α⋅β n_z')
assert ascii_vpretty(w) == expected
assert unicode_vpretty(w) == uexpected
expected = """\
2
a b + c c
- n_x + ----- n_y + -- n_z
b a b\
"""
uexpected = u("""\
2
a b + c c
─ n_x + ───── n_y + ── n_z
b a b\
""")
assert ascii_vpretty(o) == expected
assert unicode_vpretty(o) == uexpected
def test_vector_latex():
a, b, c, d, omega = symbols('a, b, c, d, omega')
v = (a ** 2 + b / c) * A.x + sqrt(d) * A.y + cos(omega) * A.z
assert v._latex() == (r'(a^{2} + \frac{b}{c})\mathbf{\hat{a}_x} + '
r'\sqrt{d}\mathbf{\hat{a}_y} + '
r'\operatorname{cos}\left(\omega\right)'
r'\mathbf{\hat{a}_z}')
theta, omega, alpha, q = dynamicsymbols('theta, omega, alpha, q')
v = theta * A.x + omega * omega * A.y + (q * alpha) * A.z
assert v._latex() == (r'\theta\mathbf{\hat{a}_x} + '
r'\omega^{2}\mathbf{\hat{a}_y} + '
r'\alpha q\mathbf{\hat{a}_z}')
phi1, phi2, phi3 = dynamicsymbols('phi1, phi2, phi3')
theta1, theta2, theta3 = symbols('theta1, theta2, theta3')
v = (sin(theta1) * A.x +
cos(phi1) * cos(phi2) * A.y +
cos(theta1 + phi3) * A.z)
assert v._latex() == (r'\operatorname{sin}\left(\theta_{1}\right)'
r'\mathbf{\hat{a}_x} + \operatorname{cos}'
r'\left(\phi_{1}\right) \operatorname{cos}'
r'\left(\phi_{2}\right)\mathbf{\hat{a}_y} + '
r'\operatorname{cos}\left(\theta_{1} + '
r'\phi_{3}\right)\mathbf{\hat{a}_z}')
N = ReferenceFrame('N')
a, b, c, d, omega = symbols('a, b, c, d, omega')
v = (a ** 2 + b / c) * N.x + sqrt(d) * N.y + cos(omega) * N.z
expected = (r'(a^{2} + \frac{b}{c})\mathbf{\hat{n}_x} + '
r'\sqrt{d}\mathbf{\hat{n}_y} + '
r'\operatorname{cos}\left(\omega\right)'
r'\mathbf{\hat{n}_z}')
assert v._latex() == expected
lp = VectorLatexPrinter()
assert lp.doprint(v) == expected
# Try custom unit vectors.
N = ReferenceFrame('N', latexs=(r'\hat{i}', r'\hat{j}', r'\hat{k}'))
v = (a ** 2 + b / c) * N.x + sqrt(d) * N.y + cos(omega) * N.z
expected = (r'(a^{2} + \frac{b}{c})\hat{i} + '
r'\sqrt{d}\hat{j} + '
r'\operatorname{cos}\left(\omega\right)\hat{k}')
assert v._latex() == expected
def test_vector_latex_with_functions():
N = ReferenceFrame('N')
omega, alpha = dynamicsymbols('omega, alpha')
v = omega.diff() * N.x
assert v._latex() == r'\dot{\omega}\mathbf{\hat{n}_x}'
v = omega.diff() ** alpha * N.x
assert v._latex() == (r'\dot{\omega}^{\alpha}'
r'\mathbf{\hat{n}_x}')
def test_dyadic_pretty_print():
expected = """\
2
a n_x|n_y + b n_y|n_y + c*sin(alpha) n_z|n_y\
"""
uexpected = u("""\
2
a n_x⊗n_y + b n_y⊗n_y + c⋅sin(α) n_z⊗n_y\
""")
assert ascii_vpretty(y) == expected
assert unicode_vpretty(y) == uexpected
expected = u('alpha n_x|n_x + sin(omega) n_y|n_z + alpha*beta n_z|n_x')
uexpected = u('α n_x⊗n_x + sin(ω) n_y⊗n_z + α⋅β n_z⊗n_x')
assert ascii_vpretty(x) == expected
assert unicode_vpretty(x) == uexpected
def test_dyadic_latex():
expected = (r'a^{2}\mathbf{\hat{n}_x}\otimes \mathbf{\hat{n}_y} + '
r'b\mathbf{\hat{n}_y}\otimes \mathbf{\hat{n}_y} + '
r'c \operatorname{sin}\left(\alpha\right)'
r'\mathbf{\hat{n}_z}\otimes \mathbf{\hat{n}_y}')
assert y._latex() == expected
expected = (r'\alpha\mathbf{\hat{n}_x}\otimes \mathbf{\hat{n}_x} + '
r'\operatorname{sin}\left(\omega\right)\mathbf{\hat{n}_y}'
r'\otimes \mathbf{\hat{n}_z} + '
r'\alpha \beta\mathbf{\hat{n}_z}\otimes \mathbf{\hat{n}_x}')
assert x._latex() == expected
def test_vlatex(): # vlatex is broken #12078
from sympy.physics.vector import vlatex
x = symbols('x')
J = symbols('J')
f = Function('f')
g = Function('g')
h = Function('h')
expected = r'J \left(\frac{d}{d x} g{\left(x \right)} - \frac{d}{d x} h{\left(x \right)}\right)'
expr = J*f(x).diff(x).subs(f(x), g(x)-h(x))
assert vlatex(expr) == expected
def test_issue_13354():
"""
Test for proper pretty printing of physics vectors with ADD
instances in arguments.
Test is exactly the one suggested in the original bug report by
@moorepants.
"""
a, b, c = symbols('a, b, c')
A = ReferenceFrame('A')
v = a * A.x + b * A.y + c * A.z
w = b * A.x + c * A.y + a * A.z
z = w + v
expected = """(a + b) a_x + (b + c) a_y + (a + c) a_z"""
assert ascii_vpretty(z) == expected
|
f2de6269eba80c05f6fa8fb6dee8217e87fdd6587510ba49eeed5d296e760ef6
|
from __future__ import print_function, division
from sympy import S, Dict, Basic, Tuple
from sympy.core.sympify import _sympify
from sympy.tensor.array.mutable_ndim_array import MutableNDimArray
from sympy.tensor.array.ndim_array import NDimArray, ImmutableNDimArray
import functools
class SparseNDimArray(NDimArray):
def __new__(self, *args, **kwargs):
return ImmutableSparseNDimArray(*args, **kwargs)
def __getitem__(self, index):
"""
Get an element from a sparse N-dim array.
Examples
========
>>> from sympy import MutableSparseNDimArray
>>> a = MutableSparseNDimArray(range(4), (2, 2))
>>> a
[[0, 1], [2, 3]]
>>> a[0, 0]
0
>>> a[1, 1]
3
>>> a[0]
0
>>> a[2]
2
Symbolic indexing:
>>> from sympy.abc import i, j
>>> a[i, j]
[[0, 1], [2, 3]][i, j]
Replace `i` and `j` to get element `(0, 0)`:
>>> a[i, j].subs({i: 0, j: 0})
0
"""
syindex = self._check_symbolic_index(index)
if syindex is not None:
return syindex
# `index` is a tuple with one or more slices:
if isinstance(index, tuple) and any([isinstance(i, slice) for i in index]):
sl_factors, eindices = self._get_slice_data_for_array_access(index)
array = [self._sparse_array.get(self._parse_index(i), S.Zero) for i in eindices]
nshape = [len(el) for i, el in enumerate(sl_factors) if isinstance(index[i], slice)]
return type(self)(array, nshape)
else:
# `index` is a single slice:
if isinstance(index, slice):
start, stop, step = index.indices(self._loop_size)
retvec = [self._sparse_array.get(ind, S.Zero) for ind in range(start, stop, step)]
return retvec
# `index` is a number or a tuple without any slice:
else:
index = self._parse_index(index)
return self._sparse_array.get(index, S.Zero)
@classmethod
def zeros(cls, *shape):
"""
Return a sparse N-dim array of zeros.
"""
return cls({}, shape)
def tomatrix(self):
"""
Converts MutableDenseNDimArray to Matrix. Can convert only 2-dim array, else will raise error.
Examples
========
>>> from sympy import MutableSparseNDimArray
>>> a = MutableSparseNDimArray([1 for i in range(9)], (3, 3))
>>> b = a.tomatrix()
>>> b
Matrix([
[1, 1, 1],
[1, 1, 1],
[1, 1, 1]])
"""
from sympy.matrices import SparseMatrix
if self.rank() != 2:
raise ValueError('Dimensions must be of size of 2')
mat_sparse = {}
for key, value in self._sparse_array.items():
mat_sparse[self._get_tuple_index(key)] = value
return SparseMatrix(self.shape[0], self.shape[1], mat_sparse)
def __iter__(self):
def iterator():
for i in range(self._loop_size):
yield self[i]
return iterator()
def reshape(self, *newshape):
new_total_size = functools.reduce(lambda x,y: x*y, newshape)
if new_total_size != self._loop_size:
raise ValueError("Invalid reshape parameters " + newshape)
return type(self)(*(newshape + (self._array,)))
class ImmutableSparseNDimArray(SparseNDimArray, ImmutableNDimArray):
def __new__(cls, iterable=None, shape=None, **kwargs):
from sympy.utilities.iterables import flatten
shape, flat_list = cls._handle_ndarray_creation_inputs(iterable, shape, **kwargs)
shape = Tuple(*map(_sympify, shape))
cls._check_special_bounds(flat_list, shape)
loop_size = functools.reduce(lambda x,y: x*y, shape) if shape else 0
# Sparse array:
if isinstance(flat_list, (dict, Dict)):
sparse_array = Dict(flat_list)
else:
sparse_array = {}
for i, el in enumerate(flatten(flat_list)):
if el != 0:
sparse_array[i] = _sympify(el)
sparse_array = Dict(sparse_array)
self = Basic.__new__(cls, sparse_array, shape, **kwargs)
self._shape = shape
self._rank = len(shape)
self._loop_size = loop_size
self._sparse_array = sparse_array
return self
def __setitem__(self, index, value):
raise TypeError("immutable N-dim array")
def as_mutable(self):
return MutableSparseNDimArray(self)
class MutableSparseNDimArray(MutableNDimArray, SparseNDimArray):
def __new__(cls, iterable=None, shape=None, **kwargs):
from sympy.utilities.iterables import flatten
shape, flat_list = cls._handle_ndarray_creation_inputs(iterable, shape, **kwargs)
self = object.__new__(cls)
self._shape = shape
self._rank = len(shape)
self._loop_size = functools.reduce(lambda x,y: x*y, shape) if shape else 0
# Sparse array:
if isinstance(flat_list, (dict, Dict)):
self._sparse_array = dict(flat_list)
return self
self._sparse_array = {}
for i, el in enumerate(flatten(flat_list)):
if el != 0:
self._sparse_array[i] = _sympify(el)
return self
def __setitem__(self, index, value):
"""Allows to set items to MutableDenseNDimArray.
Examples
========
>>> from sympy import MutableSparseNDimArray
>>> a = MutableSparseNDimArray.zeros(2, 2)
>>> a[0, 0] = 1
>>> a[1, 1] = 1
>>> a
[[1, 0], [0, 1]]
"""
if isinstance(index, tuple) and any([isinstance(i, slice) for i in index]):
value, eindices, slice_offsets = self._get_slice_data_for_array_assignment(index, value)
for i in eindices:
other_i = [ind - j for ind, j in zip(i, slice_offsets) if j is not None]
other_value = value[other_i]
complete_index = self._parse_index(i)
if other_value != 0:
self._sparse_array[complete_index] = other_value
elif complete_index in self._sparse_array:
self._sparse_array.pop(complete_index)
else:
index = self._parse_index(index)
value = _sympify(value)
if value == 0 and index in self._sparse_array:
self._sparse_array.pop(index)
else:
self._sparse_array[index] = value
def as_immutable(self):
return ImmutableSparseNDimArray(self)
@property
def free_symbols(self):
return {i for j in self._sparse_array.values() for i in j.free_symbols}
|
d45e2a1a2e5032c1539ef84196a888ce684be2e0b6626109be287fe4df25ef16
|
from __future__ import print_function, division
from sympy import Basic
from sympy.core.expr import Expr
from sympy.core.numbers import Integer
from sympy.core.sympify import sympify
from sympy.core.compatibility import SYMPY_INTS, Iterable
import itertools
class NDimArray(object):
"""
Examples
========
Create an N-dim array of zeros:
>>> from sympy import MutableDenseNDimArray
>>> a = MutableDenseNDimArray.zeros(2, 3, 4)
>>> a
[[[0, 0, 0, 0], [0, 0, 0, 0], [0, 0, 0, 0]], [[0, 0, 0, 0], [0, 0, 0, 0], [0, 0, 0, 0]]]
Create an N-dim array from a list;
>>> a = MutableDenseNDimArray([[2, 3], [4, 5]])
>>> a
[[2, 3], [4, 5]]
>>> b = MutableDenseNDimArray([[[1, 2], [3, 4], [5, 6]], [[7, 8], [9, 10], [11, 12]]])
>>> b
[[[1, 2], [3, 4], [5, 6]], [[7, 8], [9, 10], [11, 12]]]
Create an N-dim array from a flat list with dimension shape:
>>> a = MutableDenseNDimArray([1, 2, 3, 4, 5, 6], (2, 3))
>>> a
[[1, 2, 3], [4, 5, 6]]
Create an N-dim array from a matrix:
>>> from sympy import Matrix
>>> a = Matrix([[1,2],[3,4]])
>>> a
Matrix([
[1, 2],
[3, 4]])
>>> b = MutableDenseNDimArray(a)
>>> b
[[1, 2], [3, 4]]
Arithmetic operations on N-dim arrays
>>> a = MutableDenseNDimArray([1, 1, 1, 1], (2, 2))
>>> b = MutableDenseNDimArray([4, 4, 4, 4], (2, 2))
>>> c = a + b
>>> c
[[5, 5], [5, 5]]
>>> a - b
[[-3, -3], [-3, -3]]
"""
_diff_wrt = True
def __new__(cls, iterable, shape=None, **kwargs):
from sympy.tensor.array import ImmutableDenseNDimArray
return ImmutableDenseNDimArray(iterable, shape, **kwargs)
def _parse_index(self, index):
if isinstance(index, (SYMPY_INTS, Integer)):
if index >= self._loop_size:
raise ValueError("index out of range")
return index
if len(index) != self._rank:
raise ValueError('Wrong number of array axes')
real_index = 0
# check if input index can exist in current indexing
for i in range(self._rank):
if index[i] >= self.shape[i]:
raise ValueError('Index ' + str(index) + ' out of border')
real_index = real_index*self.shape[i] + index[i]
return real_index
def _get_tuple_index(self, integer_index):
index = []
for i, sh in enumerate(reversed(self.shape)):
index.append(integer_index % sh)
integer_index //= sh
index.reverse()
return tuple(index)
def _check_symbolic_index(self, index):
# Check if any index is symbolic:
tuple_index = (index if isinstance(index, tuple) else (index,))
if any([(isinstance(i, Expr) and (not i.is_number)) for i in tuple_index]):
for i, nth_dim in zip(tuple_index, self.shape):
if ((i < 0) == True) or ((i >= nth_dim) == True):
raise ValueError("index out of range")
from sympy.tensor import Indexed
return Indexed(self, *tuple_index)
return None
def _setter_iterable_check(self, value):
from sympy.matrices.matrices import MatrixBase
if isinstance(value, (Iterable, MatrixBase, NDimArray)):
raise NotImplementedError
@classmethod
def _scan_iterable_shape(cls, iterable):
def f(pointer):
if not isinstance(pointer, Iterable):
return [pointer], ()
result = []
elems, shapes = zip(*[f(i) for i in pointer])
if len(set(shapes)) != 1:
raise ValueError("could not determine shape unambiguously")
for i in elems:
result.extend(i)
return result, (len(shapes),)+shapes[0]
return f(iterable)
@classmethod
def _handle_ndarray_creation_inputs(cls, iterable=None, shape=None, **kwargs):
from sympy.matrices.matrices import MatrixBase
if shape is None and iterable is None:
shape = ()
iterable = ()
# Construction from another `NDimArray`:
elif shape is None and isinstance(iterable, NDimArray):
shape = iterable.shape
iterable = list(iterable)
# Construct N-dim array from an iterable (numpy arrays included):
elif shape is None and isinstance(iterable, Iterable):
iterable, shape = cls._scan_iterable_shape(iterable)
# Construct N-dim array from a Matrix:
elif shape is None and isinstance(iterable, MatrixBase):
shape = iterable.shape
# Construct N-dim array from another N-dim array:
elif shape is None and isinstance(iterable, NDimArray):
shape = iterable.shape
# Construct NDimArray(iterable, shape)
elif shape is not None:
pass
else:
shape = ()
iterable = (iterable,)
if isinstance(shape, (SYMPY_INTS, Integer)):
shape = (shape,)
if any([not isinstance(dim, (SYMPY_INTS, Integer)) for dim in shape]):
raise TypeError("Shape should contain integers only.")
return tuple(shape), iterable
def __len__(self):
"""Overload common function len(). Returns number of elements in array.
Examples
========
>>> from sympy import MutableDenseNDimArray
>>> a = MutableDenseNDimArray.zeros(3, 3)
>>> a
[[0, 0, 0], [0, 0, 0], [0, 0, 0]]
>>> len(a)
9
"""
return self._loop_size
@property
def shape(self):
"""
Returns array shape (dimension).
Examples
========
>>> from sympy import MutableDenseNDimArray
>>> a = MutableDenseNDimArray.zeros(3, 3)
>>> a.shape
(3, 3)
"""
return self._shape
def rank(self):
"""
Returns rank of array.
Examples
========
>>> from sympy import MutableDenseNDimArray
>>> a = MutableDenseNDimArray.zeros(3,4,5,6,3)
>>> a.rank()
5
"""
return self._rank
def diff(self, *args, **kwargs):
"""
Calculate the derivative of each element in the array.
Examples
========
>>> from sympy import ImmutableDenseNDimArray
>>> from sympy.abc import x, y
>>> M = ImmutableDenseNDimArray([[x, y], [1, x*y]])
>>> M.diff(x)
[[1, 0], [0, y]]
"""
from sympy import Derivative
kwargs.setdefault('evaluate', True)
return Derivative(self.as_immutable(), *args, **kwargs)
def _accept_eval_derivative(self, s):
return s._visit_eval_derivative_array(self)
def _visit_eval_derivative_scalar(self, base):
# Types are (base: scalar, self: array)
return self.applyfunc(lambda x: base.diff(x))
def _visit_eval_derivative_array(self, base):
# Types are (base: array/matrix, self: array)
from sympy import derive_by_array
return derive_by_array(base, self)
def _eval_derivative_n_times(self, s, n):
return Basic._eval_derivative_n_times(self, s, n)
def _eval_derivative(self, arg):
from sympy import derive_by_array
from sympy import Tuple
from sympy.matrices.common import MatrixCommon
if isinstance(arg, (Iterable, Tuple, MatrixCommon, NDimArray)):
return derive_by_array(self, arg)
else:
return self.applyfunc(lambda x: x.diff(arg))
def applyfunc(self, f):
"""Apply a function to each element of the N-dim array.
Examples
========
>>> from sympy import ImmutableDenseNDimArray
>>> m = ImmutableDenseNDimArray([i*2+j for i in range(2) for j in range(2)], (2, 2))
>>> m
[[0, 1], [2, 3]]
>>> m.applyfunc(lambda i: 2*i)
[[0, 2], [4, 6]]
"""
return type(self)(map(f, self), self.shape)
def __str__(self):
"""Returns string, allows to use standard functions print() and str().
Examples
========
>>> from sympy import MutableDenseNDimArray
>>> a = MutableDenseNDimArray.zeros(2, 2)
>>> a
[[0, 0], [0, 0]]
"""
def f(sh, shape_left, i, j):
if len(shape_left) == 1:
return "["+", ".join([str(self[e]) for e in range(i, j)])+"]"
sh //= shape_left[0]
return "[" + ", ".join([f(sh, shape_left[1:], i+e*sh, i+(e+1)*sh) for e in range(shape_left[0])]) + "]" # + "\n"*len(shape_left)
if self.rank() == 0:
return self[()].__str__()
return f(self._loop_size, self.shape, 0, self._loop_size)
def __repr__(self):
return self.__str__()
# We don't define _repr_png_ here because it would add a large amount of
# data to any notebook containing SymPy expressions, without adding
# anything useful to the notebook. It can still enabled manually, e.g.,
# for the qtconsole, with init_printing().
def _repr_latex_(self):
"""
IPython/Jupyter LaTeX printing
To change the behavior of this (e.g., pass in some settings to LaTeX),
use init_printing(). init_printing() will also enable LaTeX printing
for built in numeric types like ints and container types that contain
SymPy objects, like lists and dictionaries of expressions.
"""
from sympy.printing.latex import latex
s = latex(self, mode='plain')
return "$\\displaystyle %s$" % s
_repr_latex_orig = _repr_latex_
def tolist(self):
"""
Converting MutableDenseNDimArray to one-dim list
Examples
========
>>> from sympy import MutableDenseNDimArray
>>> a = MutableDenseNDimArray([1, 2, 3, 4], (2, 2))
>>> a
[[1, 2], [3, 4]]
>>> b = a.tolist()
>>> b
[[1, 2], [3, 4]]
"""
def f(sh, shape_left, i, j):
if len(shape_left) == 1:
return [self[e] for e in range(i, j)]
result = []
sh //= shape_left[0]
for e in range(shape_left[0]):
result.append(f(sh, shape_left[1:], i+e*sh, i+(e+1)*sh))
return result
return f(self._loop_size, self.shape, 0, self._loop_size)
def __add__(self, other):
if not isinstance(other, NDimArray):
raise TypeError(str(other))
if self.shape != other.shape:
raise ValueError("array shape mismatch")
result_list = [i+j for i,j in zip(self, other)]
return type(self)(result_list, self.shape)
def __sub__(self, other):
if not isinstance(other, NDimArray):
raise TypeError(str(other))
if self.shape != other.shape:
raise ValueError("array shape mismatch")
result_list = [i-j for i,j in zip(self, other)]
return type(self)(result_list, self.shape)
def __mul__(self, other):
from sympy.matrices.matrices import MatrixBase
if isinstance(other, (Iterable, NDimArray, MatrixBase)):
raise ValueError("scalar expected, use tensorproduct(...) for tensorial product")
other = sympify(other)
result_list = [i*other for i in self]
return type(self)(result_list, self.shape)
def __rmul__(self, other):
from sympy.matrices.matrices import MatrixBase
if isinstance(other, (Iterable, NDimArray, MatrixBase)):
raise ValueError("scalar expected, use tensorproduct(...) for tensorial product")
other = sympify(other)
result_list = [other*i for i in self]
return type(self)(result_list, self.shape)
def __div__(self, other):
from sympy.matrices.matrices import MatrixBase
if isinstance(other, (Iterable, NDimArray, MatrixBase)):
raise ValueError("scalar expected")
other = sympify(other)
result_list = [i/other for i in self]
return type(self)(result_list, self.shape)
def __rdiv__(self, other):
raise NotImplementedError('unsupported operation on NDimArray')
def __neg__(self):
result_list = [-i for i in self]
return type(self)(result_list, self.shape)
def __eq__(self, other):
"""
NDimArray instances can be compared to each other.
Instances equal if they have same shape and data.
Examples
========
>>> from sympy import MutableDenseNDimArray
>>> a = MutableDenseNDimArray.zeros(2, 3)
>>> b = MutableDenseNDimArray.zeros(2, 3)
>>> a == b
True
>>> c = a.reshape(3, 2)
>>> c == b
False
>>> a[0,0] = 1
>>> b[0,0] = 2
>>> a == b
False
"""
if not isinstance(other, NDimArray):
return False
return (self.shape == other.shape) and (list(self) == list(other))
def __ne__(self, other):
return not self == other
__truediv__ = __div__
__rtruediv__ = __rdiv__
def _eval_transpose(self):
if self.rank() != 2:
raise ValueError("array rank not 2")
from .arrayop import permutedims
return permutedims(self, (1, 0))
def transpose(self):
return self._eval_transpose()
def _eval_conjugate(self):
return self.func([i.conjugate() for i in self], self.shape)
def conjugate(self):
return self._eval_conjugate()
def _eval_adjoint(self):
return self.transpose().conjugate()
def adjoint(self):
return self._eval_adjoint()
def _slice_expand(self, s, dim):
if not isinstance(s, slice):
return (s,)
start, stop, step = s.indices(dim)
return [start + i*step for i in range((stop-start)//step)]
def _get_slice_data_for_array_access(self, index):
sl_factors = [self._slice_expand(i, dim) for (i, dim) in zip(index, self.shape)]
eindices = itertools.product(*sl_factors)
return sl_factors, eindices
def _get_slice_data_for_array_assignment(self, index, value):
if not isinstance(value, NDimArray):
value = type(self)(value)
sl_factors, eindices = self._get_slice_data_for_array_access(index)
slice_offsets = [min(i) if isinstance(i, list) else None for i in sl_factors]
# TODO: add checks for dimensions for `value`?
return value, eindices, slice_offsets
@classmethod
def _check_special_bounds(cls, flat_list, shape):
if shape == () and len(flat_list) != 1:
raise ValueError("arrays without shape need one scalar value")
if shape == (0,) and len(flat_list) > 0:
raise ValueError("if array shape is (0,) there cannot be elements")
class ImmutableNDimArray(NDimArray, Basic):
_op_priority = 11.0
def __hash__(self):
return Basic.__hash__(self)
def as_immutable(self):
return self
def as_mutable(self):
raise NotImplementedError("abstract method")
|
05621685e3a105e457422f80a9d4ddcd159d5219997389491ca086e4281699a7
|
from functools import wraps
from sympy import Matrix, eye, Integer, expand, Indexed, Sum
from sympy.combinatorics import Permutation
from sympy.core import S, Rational, Symbol, Basic, Add
from sympy.core.containers import Tuple
from sympy.core.symbol import symbols
from sympy.functions.elementary.miscellaneous import sqrt
from sympy.printing.pretty.pretty import pretty
from sympy.tensor.array import Array
from sympy.tensor.tensor import TensorIndexType, tensor_indices, TensorSymmetry, \
get_symmetric_group_sgs, TensorType, TensorIndex, tensor_mul, TensAdd, \
riemann_cyclic_replace, riemann_cyclic, TensMul, tensorsymmetry, tensorhead, \
TensorManager, TensExpr, TensorHead, canon_bp
from sympy.utilities.pytest import raises, XFAIL, ignore_warnings
from sympy.utilities.exceptions import SymPyDeprecationWarning
from sympy.core.compatibility import range
from sympy.matrices import diag
def filter_warnings_decorator(f):
@wraps(f)
def wrapper():
with ignore_warnings(SymPyDeprecationWarning):
f()
return wrapper
def _is_equal(arg1, arg2):
if isinstance(arg1, TensExpr):
return arg1.equals(arg2)
elif isinstance(arg2, TensExpr):
return arg2.equals(arg1)
return arg1 == arg2
#################### Tests from tensor_can.py #######################
def test_canonicalize_no_slot_sym():
# A_d0 * B^d0; T_c = A^d0*B_d0
Lorentz = TensorIndexType('Lorentz', dummy_fmt='L')
a, b, d0, d1 = tensor_indices('a,b,d0,d1', Lorentz)
sym1 = tensorsymmetry([1])
S1 = TensorType([Lorentz], sym1)
A, B = S1('A,B')
t = A(-d0)*B(d0)
tc = t.canon_bp()
assert str(tc) == 'A(L_0)*B(-L_0)'
# A^a * B^b; T_c = T
t = A(a)*B(b)
tc = t.canon_bp()
assert tc == t
# B^b * A^a
t1 = B(b)*A(a)
tc = t1.canon_bp()
assert str(tc) == 'A(a)*B(b)'
# A symmetric
# A^{b}_{d0}*A^{d0, a}; T_c = A^{a d0}*A{b}_{d0}
sym2 = tensorsymmetry([1]*2)
S2 = TensorType([Lorentz]*2, sym2)
A = S2('A')
t = A(b, -d0)*A(d0, a)
tc = t.canon_bp()
assert str(tc) == 'A(a, L_0)*A(b, -L_0)'
# A^{d1}_{d0}*B^d0*C_d1
# T_c = A^{d0 d1}*B_d0*C_d1
B, C = S1('B,C')
t = A(d1, -d0)*B(d0)*C(-d1)
tc = t.canon_bp()
assert str(tc) == 'A(L_0, L_1)*B(-L_0)*C(-L_1)'
# A without symmetry
# A^{d1}_{d0}*B^d0*C_d1 ord=[d0,-d0,d1,-d1]; g = [2,1,0,3,4,5]
# T_c = A^{d0 d1}*B_d1*C_d0; can = [0,2,3,1,4,5]
nsym2 = tensorsymmetry([1],[1])
NS2 = TensorType([Lorentz]*2, nsym2)
A = NS2('A')
B, C = S1('B, C')
t = A(d1, -d0)*B(d0)*C(-d1)
tc = t.canon_bp()
assert str(tc) == 'A(L_0, L_1)*B(-L_1)*C(-L_0)'
# A, B without symmetry
# A^{d1}_{d0}*B_{d1}^{d0}
# T_c = A^{d0 d1}*B_{d0 d1}
B = NS2('B')
t = A(d1, -d0)*B(-d1, d0)
tc = t.canon_bp()
assert str(tc) == 'A(L_0, L_1)*B(-L_0, -L_1)'
# A_{d0}^{d1}*B_{d1}^{d0}
# T_c = A^{d0 d1}*B_{d1 d0}
t = A(-d0, d1)*B(-d1, d0)
tc = t.canon_bp()
assert str(tc) == 'A(L_0, L_1)*B(-L_1, -L_0)'
# A, B, C without symmetry
# A^{d1 d0}*B_{a d0}*C_{d1 b}
# T_c=A^{d0 d1}*B_{a d1}*C_{d0 b}
C = NS2('C')
t = A(d1, d0)*B(-a, -d0)*C(-d1, -b)
tc = t.canon_bp()
assert str(tc) == 'A(L_0, L_1)*B(-a, -L_1)*C(-L_0, -b)'
# A symmetric, B and C without symmetry
# A^{d1 d0}*B_{a d0}*C_{d1 b}
# T_c = A^{d0 d1}*B_{a d0}*C_{d1 b}
A = S2('A')
t = A(d1, d0)*B(-a, -d0)*C(-d1, -b)
tc = t.canon_bp()
assert str(tc) == 'A(L_0, L_1)*B(-a, -L_0)*C(-L_1, -b)'
# A and C symmetric, B without symmetry
# A^{d1 d0}*B_{a d0}*C_{d1 b} ord=[a,b,d0,-d0,d1,-d1]
# T_c = A^{d0 d1}*B_{a d0}*C_{b d1}
C = S2('C')
t = A(d1, d0)*B(-a, -d0)*C(-d1, -b)
tc = t.canon_bp()
assert str(tc) == 'A(L_0, L_1)*B(-a, -L_0)*C(-b, -L_1)'
def test_canonicalize_no_dummies():
Lorentz = TensorIndexType('Lorentz', dummy_fmt='L')
a, b, c, d = tensor_indices('a, b, c, d', Lorentz)
sym1 = tensorsymmetry([1])
sym2 = tensorsymmetry([1]*2)
sym2a = tensorsymmetry([2])
# A commuting
# A^c A^b A^a
# T_c = A^a A^b A^c
S1 = TensorType([Lorentz], sym1)
A = S1('A')
t = A(c)*A(b)*A(a)
tc = t.canon_bp()
assert str(tc) == 'A(a)*A(b)*A(c)'
# A anticommuting
# A^c A^b A^a
# T_c = -A^a A^b A^c
A = S1('A', 1)
t = A(c)*A(b)*A(a)
tc = t.canon_bp()
assert str(tc) == '-A(a)*A(b)*A(c)'
# A commuting and symmetric
# A^{b,d}*A^{c,a}
# T_c = A^{a c}*A^{b d}
S2 = TensorType([Lorentz]*2, sym2)
A = S2('A')
t = A(b, d)*A(c, a)
tc = t.canon_bp()
assert str(tc) == 'A(a, c)*A(b, d)'
# A anticommuting and symmetric
# A^{b,d}*A^{c,a}
# T_c = -A^{a c}*A^{b d}
A = S2('A', 1)
t = A(b, d)*A(c, a)
tc = t.canon_bp()
assert str(tc) == '-A(a, c)*A(b, d)'
# A^{c,a}*A^{b,d}
# T_c = A^{a c}*A^{b d}
t = A(c, a)*A(b, d)
tc = t.canon_bp()
assert str(tc) == 'A(a, c)*A(b, d)'
def test_tensorhead_construction_without_symmetry():
L = Lorentz = TensorIndexType('Lorentz')
A1 = tensorhead('A', [L, L])
A2 = tensorhead('A', [L, L], [[1], [1]])
assert A1 == A2
A3 = tensorhead('A', [L, L], [[1, 1]]) # Symmetric
assert A1 != A3
def test_no_metric_symmetry():
# no metric symmetry; A no symmetry
# A^d1_d0 * A^d0_d1
# T_c = A^d0_d1 * A^d1_d0
Lorentz = TensorIndexType('Lorentz', metric=None, dummy_fmt='L')
d0, d1, d2, d3 = tensor_indices('d:4', Lorentz)
A = tensorhead('A', [Lorentz]*2, [[1], [1]])
t = A(d1, -d0)*A(d0, -d1)
tc = t.canon_bp()
assert str(tc) == 'A(L_0, -L_1)*A(L_1, -L_0)'
# A^d1_d2 * A^d0_d3 * A^d2_d1 * A^d3_d0
# T_c = A^d0_d1 * A^d1_d0 * A^d2_d3 * A^d3_d2
t = A(d1, -d2)*A(d0, -d3)*A(d2,-d1)*A(d3,-d0)
tc = t.canon_bp()
assert str(tc) == 'A(L_0, -L_1)*A(L_1, -L_0)*A(L_2, -L_3)*A(L_3, -L_2)'
# A^d0_d2 * A^d1_d3 * A^d3_d0 * A^d2_d1
# T_c = A^d0_d1 * A^d1_d2 * A^d2_d3 * A^d3_d0
t = A(d0, -d1)*A(d1, -d2)*A(d2, -d3)*A(d3,-d0)
tc = t.canon_bp()
assert str(tc) == 'A(L_0, -L_1)*A(L_1, -L_2)*A(L_2, -L_3)*A(L_3, -L_0)'
def test_canonicalize1():
Lorentz = TensorIndexType('Lorentz', dummy_fmt='L')
a, a0, a1, a2, a3, b, d0, d1, d2, d3 = \
tensor_indices('a,a0,a1,a2,a3,b,d0,d1,d2,d3', Lorentz)
sym1 = tensorsymmetry([1])
base3, gens3 = get_symmetric_group_sgs(3)
sym2 = tensorsymmetry([1]*2)
sym2a = tensorsymmetry([2])
sym3 = tensorsymmetry([1]*3)
sym3a = tensorsymmetry([3])
# A_d0*A^d0; ord = [d0,-d0]
# T_c = A^d0*A_d0
S1 = TensorType([Lorentz], sym1)
A = S1('A')
t = A(-d0)*A(d0)
tc = t.canon_bp()
assert str(tc) == 'A(L_0)*A(-L_0)'
# A commuting
# A_d0*A_d1*A_d2*A^d2*A^d1*A^d0
# T_c = A^d0*A_d0*A^d1*A_d1*A^d2*A_d2
t = A(-d0)*A(-d1)*A(-d2)*A(d2)*A(d1)*A(d0)
tc = t.canon_bp()
assert str(tc) == 'A(L_0)*A(-L_0)*A(L_1)*A(-L_1)*A(L_2)*A(-L_2)'
# A anticommuting
# A_d0*A_d1*A_d2*A^d2*A^d1*A^d0
# T_c 0
A = S1('A', 1)
t = A(-d0)*A(-d1)*A(-d2)*A(d2)*A(d1)*A(d0)
tc = t.canon_bp()
assert tc == 0
# A commuting symmetric
# A^{d0 b}*A^a_d1*A^d1_d0
# T_c = A^{a d0}*A^{b d1}*A_{d0 d1}
S2 = TensorType([Lorentz]*2, sym2)
A = S2('A')
t = A(d0, b)*A(a, -d1)*A(d1, -d0)
tc = t.canon_bp()
assert str(tc) == 'A(a, L_0)*A(b, L_1)*A(-L_0, -L_1)'
# A, B commuting symmetric
# A^{d0 b}*A^d1_d0*B^a_d1
# T_c = A^{b d0}*A_d0^d1*B^a_d1
B = S2('B')
t = A(d0, b)*A(d1, -d0)*B(a, -d1)
tc = t.canon_bp()
assert str(tc) == 'A(b, L_0)*A(-L_0, L_1)*B(a, -L_1)'
# A commuting symmetric
# A^{d1 d0 b}*A^{a}_{d1 d0}; ord=[a,b, d0,-d0,d1,-d1]
# T_c = A^{a d0 d1}*A^{b}_{d0 d1}
S3 = TensorType([Lorentz]*3, sym3)
A = S3('A')
t = A(d1, d0, b)*A(a, -d1, -d0)
tc = t.canon_bp()
assert str(tc) == 'A(a, L_0, L_1)*A(b, -L_0, -L_1)'
# A^{d3 d0 d2}*A^a0_{d1 d2}*A^d1_d3^a1*A^{a2 a3}_d0
# T_c = A^{a0 d0 d1}*A^a1_d0^d2*A^{a2 a3 d3}*A_{d1 d2 d3}
t = A(d3, d0, d2)*A(a0, -d1, -d2)*A(d1, -d3, a1)*A(a2, a3, -d0)
tc = t.canon_bp()
assert str(tc) == 'A(a0, L_0, L_1)*A(a1, -L_0, L_2)*A(a2, a3, L_3)*A(-L_1, -L_2, -L_3)'
# A commuting symmetric, B antisymmetric
# A^{d0 d1 d2} * A_{d2 d3 d1} * B_d0^d3
# in this esxample and in the next three,
# renaming dummy indices and using symmetry of A,
# T = A^{d0 d1 d2} * A_{d0 d1 d3} * B_d2^d3
# can = 0
S2a = TensorType([Lorentz]*2, sym2a)
A = S3('A')
B = S2a('B')
t = A(d0, d1, d2)*A(-d2, -d3, -d1)*B(-d0, d3)
tc = t.canon_bp()
assert tc == 0
# A anticommuting symmetric, B anticommuting
# A^{d0 d1 d2} * A_{d2 d3 d1} * B_d0^d3
# T_c = A^{d0 d1 d2} * A_{d0 d1}^d3 * B_{d2 d3}
A = S3('A', 1)
B = S2a('B')
t = A(d0, d1, d2)*A(-d2, -d3, -d1)*B(-d0, d3)
tc = t.canon_bp()
assert str(tc) == 'A(L_0, L_1, L_2)*A(-L_0, -L_1, L_3)*B(-L_2, -L_3)'
# A anticommuting symmetric, B antisymmetric commuting, antisymmetric metric
# A^{d0 d1 d2} * A_{d2 d3 d1} * B_d0^d3
# T_c = -A^{d0 d1 d2} * A_{d0 d1}^d3 * B_{d2 d3}
Spinor = TensorIndexType('Spinor', metric=1, dummy_fmt='S')
a, a0, a1, a2, a3, b, d0, d1, d2, d3 = \
tensor_indices('a,a0,a1,a2,a3,b,d0,d1,d2,d3', Spinor)
S3 = TensorType([Spinor]*3, sym3)
S2a = TensorType([Spinor]*2, sym2a)
A = S3('A', 1)
B = S2a('B')
t = A(d0, d1, d2)*A(-d2, -d3, -d1)*B(-d0, d3)
tc = t.canon_bp()
assert str(tc) == '-A(S_0, S_1, S_2)*A(-S_0, -S_1, S_3)*B(-S_2, -S_3)'
# A anticommuting symmetric, B antisymmetric anticommuting,
# no metric symmetry
# A^{d0 d1 d2} * A_{d2 d3 d1} * B_d0^d3
# T_c = A^{d0 d1 d2} * A_{d0 d1 d3} * B_d2^d3
Mat = TensorIndexType('Mat', metric=None, dummy_fmt='M')
a, a0, a1, a2, a3, b, d0, d1, d2, d3 = \
tensor_indices('a,a0,a1,a2,a3,b,d0,d1,d2,d3', Mat)
S3 = TensorType([Mat]*3, sym3)
S2a = TensorType([Mat]*2, sym2a)
A = S3('A', 1)
B = S2a('B')
t = A(d0, d1, d2)*A(-d2, -d3, -d1)*B(-d0, d3)
tc = t.canon_bp()
assert str(tc) == 'A(M_0, M_1, M_2)*A(-M_0, -M_1, -M_3)*B(-M_2, M_3)'
# Gamma anticommuting
# Gamma_{mu nu} * gamma^rho * Gamma^{nu mu alpha}
# T_c = -Gamma^{mu nu} * gamma^rho * Gamma_{alpha mu nu}
S1 = TensorType([Lorentz], sym1)
S2a = TensorType([Lorentz]*2, sym2a)
S3a = TensorType([Lorentz]*3, sym3a)
alpha, beta, gamma, mu, nu, rho = \
tensor_indices('alpha,beta,gamma,mu,nu,rho', Lorentz)
Gamma = S1('Gamma', 2)
Gamma2 = S2a('Gamma', 2)
Gamma3 = S3a('Gamma', 2)
t = Gamma2(-mu,-nu)*Gamma(rho)*Gamma3(nu, mu, alpha)
tc = t.canon_bp()
assert str(tc) == '-Gamma(L_0, L_1)*Gamma(rho)*Gamma(alpha, -L_0, -L_1)'
# Gamma_{mu nu} * Gamma^{gamma beta} * gamma_rho * Gamma^{nu mu alpha}
# T_c = Gamma^{mu nu} * Gamma^{beta gamma} * gamma_rho * Gamma^alpha_{mu nu}
t = Gamma2(mu, nu)*Gamma2(beta, gamma)*Gamma(-rho)*Gamma3(alpha, -mu, -nu)
tc = t.canon_bp()
assert str(tc) == 'Gamma(L_0, L_1)*Gamma(beta, gamma)*Gamma(-rho)*Gamma(alpha, -L_0, -L_1)'
# f^a_{b,c} antisymmetric in b,c; A_mu^a no symmetry
# f^c_{d a} * f_{c e b} * A_mu^d * A_nu^a * A^{nu e} * A^{mu b}
# g = [8,11,5, 9,13,7, 1,10, 3,4, 2,12, 0,6, 14,15]
# T_c = -f^{a b c} * f_a^{d e} * A^mu_b * A_{mu d} * A^nu_c * A_{nu e}
Flavor = TensorIndexType('Flavor', dummy_fmt='F')
a, b, c, d, e, ff = tensor_indices('a,b,c,d,e,f', Flavor)
mu, nu = tensor_indices('mu,nu', Lorentz)
sym_f = tensorsymmetry([1], [2])
S_f = TensorType([Flavor]*3, sym_f)
sym_A = tensorsymmetry([1], [1])
S_A = TensorType([Lorentz, Flavor], sym_A)
f = S_f('f')
A = S_A('A')
t = f(c, -d, -a)*f(-c, -e, -b)*A(-mu, d)*A(-nu, a)*A(nu, e)*A(mu, b)
tc = t.canon_bp()
assert str(tc) == '-f(F_0, F_1, F_2)*f(-F_0, F_3, F_4)*A(L_0, -F_1)*A(-L_0, -F_3)*A(L_1, -F_2)*A(-L_1, -F_4)'
def test_bug_correction_tensor_indices():
# to make sure that tensor_indices does not return a list if creating
# only one index:
from sympy.tensor.tensor import tensor_indices, TensorIndexType, TensorIndex
A = TensorIndexType("A")
i = tensor_indices('i', A)
assert not isinstance(i, (tuple, list))
assert isinstance(i, TensorIndex)
def test_riemann_invariants():
Lorentz = TensorIndexType('Lorentz', dummy_fmt='L')
d0, d1, d2, d3, d4, d5, d6, d7, d8, d9, d10, d11 = \
tensor_indices('d0:12', Lorentz)
# R^{d0 d1}_{d1 d0}; ord = [d0,-d0,d1,-d1]
# T_c = -R^{d0 d1}_{d0 d1}
R = tensorhead('R', [Lorentz]*4, [[2, 2]])
t = R(d0, d1, -d1, -d0)
tc = t.canon_bp()
assert str(tc) == '-R(L_0, L_1, -L_0, -L_1)'
# R_d11^d1_d0^d5 * R^{d6 d4 d0}_d5 * R_{d7 d2 d8 d9} *
# R_{d10 d3 d6 d4} * R^{d2 d7 d11}_d1 * R^{d8 d9 d3 d10}
# can = [0,2,4,6, 1,3,8,10, 5,7,12,14, 9,11,16,18, 13,15,20,22,
# 17,19,21<F10,23, 24,25]
# T_c = R^{d0 d1 d2 d3} * R_{d0 d1}^{d4 d5} * R_{d2 d3}^{d6 d7} *
# R_{d4 d5}^{d8 d9} * R_{d6 d7}^{d10 d11} * R_{d8 d9 d10 d11}
t = R(-d11,d1,-d0,d5)*R(d6,d4,d0,-d5)*R(-d7,-d2,-d8,-d9)* \
R(-d10,-d3,-d6,-d4)*R(d2,d7,d11,-d1)*R(d8,d9,d3,d10)
tc = t.canon_bp()
assert str(tc) == 'R(L_0, L_1, L_2, L_3)*R(-L_0, -L_1, L_4, L_5)*R(-L_2, -L_3, L_6, L_7)*R(-L_4, -L_5, L_8, L_9)*R(-L_6, -L_7, L_10, L_11)*R(-L_8, -L_9, -L_10, -L_11)'
def test_riemann_products():
Lorentz = TensorIndexType('Lorentz', dummy_fmt='L')
d0, d1, d2, d3, d4, d5, d6 = tensor_indices('d0:7', Lorentz)
a0, a1, a2, a3, a4, a5 = tensor_indices('a0:6', Lorentz)
a, b = tensor_indices('a,b', Lorentz)
R = tensorhead('R', [Lorentz]*4, [[2, 2]])
# R^{a b d0}_d0 = 0
t = R(a, b, d0, -d0)
tc = t.canon_bp()
assert tc == 0
# R^{d0 b a}_d0
# T_c = -R^{a d0 b}_d0
t = R(d0, b, a, -d0)
tc = t.canon_bp()
assert str(tc) == '-R(a, L_0, b, -L_0)'
# R^d1_d2^b_d0 * R^{d0 a}_d1^d2; ord=[a,b,d0,-d0,d1,-d1,d2,-d2]
# T_c = -R^{a d0 d1 d2}* R^b_{d0 d1 d2}
t = R(d1, -d2, b, -d0)*R(d0, a, -d1, d2)
tc = t.canon_bp()
assert str(tc) == '-R(a, L_0, L_1, L_2)*R(b, -L_0, -L_1, -L_2)'
# A symmetric commuting
# R^{d6 d5}_d2^d1 * R^{d4 d0 d2 d3} * A_{d6 d0} A_{d3 d1} * A_{d4 d5}
# g = [12,10,5,2, 8,0,4,6, 13,1, 7,3, 9,11,14,15]
# T_c = -R^{d0 d1 d2 d3} * R_d0^{d4 d5 d6} * A_{d1 d4}*A_{d2 d5}*A_{d3 d6}
V = tensorhead('V', [Lorentz]*2, [[1]*2])
t = R(d6, d5, -d2, d1)*R(d4, d0, d2, d3)*V(-d6, -d0)*V(-d3, -d1)*V(-d4, -d5)
tc = t.canon_bp()
assert str(tc) == '-R(L_0, L_1, L_2, L_3)*R(-L_0, L_4, L_5, L_6)*V(-L_1, -L_4)*V(-L_2, -L_5)*V(-L_3, -L_6)'
# R^{d2 a0 a2 d0} * R^d1_d2^{a1 a3} * R^{a4 a5}_{d0 d1}
# T_c = R^{a0 d0 a2 d1}*R^{a1 a3}_d0^d2*R^{a4 a5}_{d1 d2}
t = R(d2, a0, a2, d0)*R(d1, -d2, a1, a3)*R(a4, a5, -d0, -d1)
tc = t.canon_bp()
assert str(tc) == 'R(a0, L_0, a2, L_1)*R(a1, a3, -L_0, L_2)*R(a4, a5, -L_1, -L_2)'
######################################################################
def test_canonicalize2():
D = Symbol('D')
Eucl = TensorIndexType('Eucl', metric=0, dim=D, dummy_fmt='E')
i0,i1,i2,i3,i4,i5,i6,i7,i8,i9,i10,i11,i12,i13,i14 = \
tensor_indices('i0:15', Eucl)
A = tensorhead('A', [Eucl]*3, [[3]])
# two examples from Cvitanovic, Group Theory page 59
# of identities for antisymmetric tensors of rank 3
# contracted according to the Kuratowski graph eq.(6.59)
t = A(i0,i1,i2)*A(-i1,i3,i4)*A(-i3,i7,i5)*A(-i2,-i5,i6)*A(-i4,-i6,i8)
t1 = t.canon_bp()
assert t1 == 0
# eq.(6.60)
#t = A(i0,i1,i2)*A(-i1,i3,i4)*A(-i2,i5,i6)*A(-i3,i7,i8)*A(-i6,-i7,i9)*
# A(-i8,i10,i13)*A(-i5,-i10,i11)*A(-i4,-i11,i12)*A(-i3,-i12,i14)
t = A(i0,i1,i2)*A(-i1,i3,i4)*A(-i2,i5,i6)*A(-i3,i7,i8)*A(-i6,-i7,i9)*\
A(-i8,i10,i13)*A(-i5,-i10,i11)*A(-i4,-i11,i12)*A(-i9,-i12,i14)
t1 = t.canon_bp()
assert t1 == 0
def test_canonicalize3():
D = Symbol('D')
Spinor = TensorIndexType('Spinor', dim=D, metric=True, dummy_fmt='S')
a0,a1,a2,a3,a4 = tensor_indices('a0:5', Spinor)
C = Spinor.metric
chi, psi = tensorhead('chi,psi', [Spinor], [[1]], 1)
t = chi(a1)*psi(a0)
t1 = t.canon_bp()
assert t1 == t
t = psi(a1)*chi(a0)
t1 = t.canon_bp()
assert t1 == -chi(a0)*psi(a1)
class Metric(Basic):
def __new__(cls, name, antisym, **kwargs):
obj = Basic.__new__(cls, name, antisym, **kwargs)
obj.name = name
obj.antisym = antisym
return obj
def test_TensorIndexType():
D = Symbol('D')
G = Metric('g', False)
Lorentz = TensorIndexType('Lorentz', metric=G, dim=D, dummy_fmt='L')
m0, m1, m2, m3, m4 = tensor_indices('m0:5', Lorentz)
sym2 = tensorsymmetry([1]*2)
sym2n = tensorsymmetry(*get_symmetric_group_sgs(2))
assert sym2 == sym2n
g = Lorentz.metric
assert str(g) == 'g(Lorentz,Lorentz)'
assert Lorentz.eps_dim == Lorentz.dim
TSpace = TensorIndexType('TSpace')
i0, i1 = tensor_indices('i0 i1', TSpace)
g = TSpace.metric
A = tensorhead('A', [TSpace]*2, [[1]*2])
assert str(A(i0,-i0).canon_bp()) == 'A(TSpace_0, -TSpace_0)'
def test_indices():
Lorentz = TensorIndexType('Lorentz', dummy_fmt='L')
a, b, c, d = tensor_indices('a,b,c,d', Lorentz)
assert a.tensor_index_type == Lorentz
assert a != -a
A, B = tensorhead('A B', [Lorentz]*2, [[1]*2])
t = A(a,b)*B(-b,c)
indices = t.get_indices()
L_0 = TensorIndex('L_0', Lorentz)
assert indices == [a, L_0, -L_0, c]
raises(ValueError, lambda: tensor_indices(3, Lorentz))
raises(ValueError, lambda: A(a,b,c))
def test_tensorsymmetry():
Lorentz = TensorIndexType('Lorentz', dummy_fmt='L')
sym = tensorsymmetry([1]*2)
sym1 = TensorSymmetry(get_symmetric_group_sgs(2))
assert sym == sym1
sym = tensorsymmetry([2])
sym1 = TensorSymmetry(get_symmetric_group_sgs(2, 1))
assert sym == sym1
sym2 = tensorsymmetry()
assert sym2.base == Tuple() and sym2.generators == Tuple(Permutation(1))
raises(NotImplementedError, lambda: tensorsymmetry([2, 1]))
def test_TensorType():
Lorentz = TensorIndexType('Lorentz', dummy_fmt='L')
sym = tensorsymmetry([1]*2)
A = tensorhead('A', [Lorentz]*2, [[1]*2])
assert A.typ == TensorType([Lorentz]*2, sym)
assert A.types == [Lorentz]
assert A.index_types == Tuple(*[Lorentz, Lorentz])
typ = TensorType([Lorentz]*2, sym)
assert str(typ) == "TensorType(['Lorentz', 'Lorentz'])"
raises(ValueError, lambda: typ(2))
def test_TensExpr():
Lorentz = TensorIndexType('Lorentz', dummy_fmt='L')
a, b, c, d = tensor_indices('a,b,c,d', Lorentz)
g = Lorentz.metric
A, B = tensorhead('A B', [Lorentz]*2, [[1]*2])
raises(ValueError, lambda: g(c, d)/g(a, b))
raises(ValueError, lambda: S.One/g(a, b))
raises(ValueError, lambda: (A(c, d) + g(c, d))/g(a, b))
raises(ValueError, lambda: S.One/(A(c, d) + g(c, d)))
raises(ValueError, lambda: A(a, b) + A(a, c))
t = A(a, b) + B(a, b)
#raises(NotImplementedError, lambda: TensExpr.__mul__(t, 'a'))
#raises(NotImplementedError, lambda: TensExpr.__add__(t, 'a'))
#raises(NotImplementedError, lambda: TensExpr.__radd__(t, 'a'))
#raises(NotImplementedError, lambda: TensExpr.__sub__(t, 'a'))
#raises(NotImplementedError, lambda: TensExpr.__rsub__(t, 'a'))
#raises(NotImplementedError, lambda: TensExpr.__div__(t, 'a'))
#raises(NotImplementedError, lambda: TensExpr.__rdiv__(t, 'a'))
with ignore_warnings(SymPyDeprecationWarning):
# DO NOT REMOVE THIS AFTER DEPRECATION REMOVED:
raises(ValueError, lambda: A(a, b)**2)
raises(NotImplementedError, lambda: 2**A(a, b))
raises(NotImplementedError, lambda: abs(A(a, b)))
def test_TensorHead():
# simple example of algebraic expression
Lorentz = TensorIndexType('Lorentz', dummy_fmt='L')
a,b = tensor_indices('a,b', Lorentz)
# A, B symmetric
A = tensorhead('A', [Lorentz]*2, [[1]*2])
assert A.rank == 2
assert A.symmetry == tensorsymmetry([1]*2)
def test_add1():
assert TensAdd().args == ()
assert TensAdd().doit() == 0
# simple example of algebraic expression
Lorentz = TensorIndexType('Lorentz', dummy_fmt='L')
a,b,d0,d1,i,j,k = tensor_indices('a,b,d0,d1,i,j,k', Lorentz)
# A, B symmetric
A, B = tensorhead('A,B', [Lorentz]*2, [[1]*2])
t1 = A(b,-d0)*B(d0,a)
assert TensAdd(t1).equals(t1)
t2a = B(d0,a) + A(d0, a)
t2 = A(b,-d0)*t2a
assert str(t2) == 'A(b, -L_0)*(A(L_0, a) + B(L_0, a))'
t2 = t2.expand()
assert str(t2) == 'A(b, -L_0)*A(L_0, a) + A(b, -L_0)*B(L_0, a)'
t2 = t2.canon_bp()
assert str(t2) == 'A(a, L_0)*A(b, -L_0) + A(b, L_0)*B(a, -L_0)'
t2b = t2 + t1
assert str(t2b) == 'A(a, L_0)*A(b, -L_0) + A(b, -L_0)*B(L_0, a) + A(b, L_0)*B(a, -L_0)'
t2b = t2b.canon_bp()
assert str(t2b) == '2*A(b, L_0)*B(a, -L_0) + A(a, L_0)*A(b, -L_0)'
p, q, r = tensorhead('p,q,r', [Lorentz], [[1]])
t = q(d0)*2
assert str(t) == '2*q(d0)'
t = 2*q(d0)
assert str(t) == '2*q(d0)'
t1 = p(d0) + 2*q(d0)
assert str(t1) == '2*q(d0) + p(d0)'
t2 = p(-d0) + 2*q(-d0)
assert str(t2) == '2*q(-d0) + p(-d0)'
t1 = p(d0)
t3 = t1*t2
assert str(t3) == 'p(L_0)*(2*q(-L_0) + p(-L_0))'
t3 = t3.expand()
assert str(t3) == '2*p(L_0)*q(-L_0) + p(L_0)*p(-L_0)'
t3 = t2*t1
t3 = t3.expand()
assert str(t3) == '2*q(-L_0)*p(L_0) + p(-L_0)*p(L_0)'
t3 = t3.canon_bp()
assert str(t3) == '2*p(L_0)*q(-L_0) + p(L_0)*p(-L_0)'
t1 = p(d0) + 2*q(d0)
t3 = t1*t2
t3 = t3.canon_bp()
assert str(t3) == '4*p(L_0)*q(-L_0) + 4*q(L_0)*q(-L_0) + p(L_0)*p(-L_0)'
t1 = p(d0) - 2*q(d0)
assert str(t1) == '-2*q(d0) + p(d0)'
t2 = p(-d0) + 2*q(-d0)
t3 = t1*t2
t3 = t3.canon_bp()
assert t3 == p(d0)*p(-d0) - 4*q(d0)*q(-d0)
t = p(i)*p(j)*(p(k) + q(k)) + p(i)*(p(j) + q(j))*(p(k) - 3*q(k))
t = t.canon_bp()
assert t == 2*p(i)*p(j)*p(k) - 2*p(i)*p(j)*q(k) + p(i)*p(k)*q(j) - 3*p(i)*q(j)*q(k)
t1 = (p(i) + q(i) + 2*r(i))*(p(j) - q(j))
t2 = (p(j) + q(j) + 2*r(j))*(p(i) - q(i))
t = t1 + t2
t = t.canon_bp()
assert t == 2*p(i)*p(j) + 2*p(i)*r(j) + 2*p(j)*r(i) - 2*q(i)*q(j) - 2*q(i)*r(j) - 2*q(j)*r(i)
t = p(i)*q(j)/2
assert 2*t == p(i)*q(j)
t = (p(i) + q(i))/2
assert 2*t == p(i) + q(i)
t = S.One - p(i)*p(-i)
t = t.canon_bp()
tz1 = t + p(-j)*p(j)
assert tz1 != 1
tz1 = tz1.canon_bp()
assert tz1.equals(1)
t = S.One + p(i)*p(-i)
assert (t - p(-j)*p(j)).canon_bp().equals(1)
t = A(a, b) + B(a, b)
assert t.rank == 2
t1 = t - A(a, b) - B(a, b)
assert t1 == 0
t = 1 - (A(a, -a) + B(a, -a))
t1 = 1 + (A(a, -a) + B(a, -a))
assert (t + t1).expand().equals(2)
t2 = 1 + A(a, -a)
assert t1 != t2
assert t2 != TensMul.from_data(0, [], [], [])
t = p(i) + q(i)
raises(ValueError, lambda: t(i, j))
def test_special_eq_ne():
# test special equality cases:
Lorentz = TensorIndexType('Lorentz', dummy_fmt='L')
a,b,d0,d1,i,j,k = tensor_indices('a,b,d0,d1,i,j,k', Lorentz)
# A, B symmetric
A, B = tensorhead('A,B', [Lorentz]*2, [[1]*2])
p, q, r = tensorhead('p,q,r', [Lorentz], [[1]])
t = 0*A(a, b)
assert _is_equal(t, 0)
assert _is_equal(t, S.Zero)
assert p(i) != A(a, b)
assert A(a, -a) != A(a, b)
assert 0*(A(a, b) + B(a, b)) == 0
assert 0*(A(a, b) + B(a, b)) == S.Zero
assert 3*(A(a, b) - A(a, b)) == S.Zero
assert p(i) + q(i) != A(a, b)
assert p(i) + q(i) != A(a, b) + B(a, b)
assert p(i) - p(i) == 0
assert p(i) - p(i) == S.Zero
assert _is_equal(A(a, b), A(b, a))
def test_add2():
Lorentz = TensorIndexType('Lorentz', dummy_fmt='L')
m, n, p, q = tensor_indices('m,n,p,q', Lorentz)
R = tensorhead('R', [Lorentz]*4, [[2, 2]])
A = tensorhead('A', [Lorentz]*3, [[3]])
t1 = 2*R(m, n, p, q) - R(m, q, n, p) + R(m, p, n, q)
t2 = t1*A(-n, -p, -q)
t2 = t2.canon_bp()
assert t2 == 0
t1 = S(2)/3*R(m,n,p,q) - S(1)/3*R(m,q,n,p) + S(1)/3*R(m,p,n,q)
t2 = t1*A(-n, -p, -q)
t2 = t2.canon_bp()
assert t2 == 0
t = A(m, -m, n) + A(n, p, -p)
t = t.canon_bp()
assert t == 0
def test_add3():
Lorentz = TensorIndexType('Lorentz', dummy_fmt='L')
i0, i1 = tensor_indices('i0:2', Lorentz)
E, px, py, pz = symbols('E px py pz')
A = tensorhead('A', [Lorentz], [[1]])
B = tensorhead('B', [Lorentz], [[1]])
expr1 = A(i0)*A(-i0) - (E**2 - px**2 - py**2 - pz**2)
assert expr1.args == (px**2, py**2, pz**2, -E**2, A(i0)*A(-i0))
expr2 = E**2 - px**2 - py**2 - pz**2 - A(i0)*A(-i0)
assert expr2.args == (E**2, -px**2, -py**2, -pz**2, -A(i0)*A(-i0))
expr3 = A(i0)*A(-i0) - E**2 + px**2 + py**2 + pz**2
assert expr3.args == (px**2, py**2, pz**2, -E**2, A(i0)*A(-i0))
expr4 = B(i1)*B(-i1) + 2*E**2 - 2*px**2 - 2*py**2 - 2*pz**2 - A(i0)*A(-i0)
assert expr4.args == (-2*px**2, -2*py**2, -2*pz**2, 2*E**2, -A(i0)*A(-i0), B(i1)*B(-i1))
def test_mul():
from sympy.abc import x
Lorentz = TensorIndexType('Lorentz', dummy_fmt='L')
a, b, c, d = tensor_indices('a,b,c,d', Lorentz)
sym = tensorsymmetry([1]*2)
t = TensMul.from_data(S.One, [], [], [])
assert str(t) == '1'
A, B = tensorhead('A B', [Lorentz]*2, [[1]*2])
t = (1 + x)*A(a, b)
assert str(t) == '(x + 1)*A(a, b)'
assert t.index_types == [Lorentz, Lorentz]
assert t.rank == 2
assert t.dum == []
assert t.coeff == 1 + x
assert sorted(t.free) == [(a, 0), (b, 1)]
assert t.components == [A]
ts = A(a, b)
assert str(ts) == 'A(a, b)'
assert ts.index_types == [Lorentz, Lorentz]
assert ts.rank == 2
assert ts.dum == []
assert ts.coeff == 1
assert sorted(ts.free) == [(a, 0), (b, 1)]
assert ts.components == [A]
t = A(-b, a)*B(-a, c)*A(-c, d)
t1 = tensor_mul(*t.split())
assert t == t(-b, d)
assert t == t1
assert tensor_mul(*[]) == TensMul.from_data(S.One, [], [], [])
t = TensMul.from_data(1, [], [], [])
zsym = tensorsymmetry()
typ = TensorType([], zsym)
C = typ('C')
assert str(C()) == 'C'
assert str(t) == '1'
assert t == 1
raises(ValueError, lambda: A(a, b)*A(a, c))
t = A(a, b)*A(-a, c)
raises(ValueError, lambda: t(a, b, c))
def test_substitute_indices():
Lorentz = TensorIndexType('Lorentz', dummy_fmt='L')
i, j, k, l, m, n, p, q = tensor_indices('i,j,k,l,m,n,p,q', Lorentz)
A, B = tensorhead('A,B', [Lorentz]*2, [[1]*2])
t = A(i, k)*B(-k, -j)
t1 = t.substitute_indices((i, j), (j, k))
t1a = A(j, l)*B(-l, -k)
assert t1 == t1a
p = tensorhead('p', [Lorentz], [[1]])
t = p(i)
t1 = t.substitute_indices((j, k))
assert t1 == t
t1 = t.substitute_indices((i, j))
assert t1 == p(j)
t1 = t.substitute_indices((i, -j))
assert t1 == p(-j)
t1 = t.substitute_indices((-i, j))
assert t1 == p(-j)
t1 = t.substitute_indices((-i, -j))
assert t1 == p(j)
A_tmul = A(m, n)
A_c = A_tmul(m, -m)
assert _is_equal(A_c, A(n, -n))
ABm = A(i, j)*B(m, n)
ABc1 = ABm(i, j, -i, -j)
assert _is_equal(ABc1, A(i, -j)*B(-i, j))
ABc2 = ABm(i, -i, j, -j)
assert _is_equal(ABc2, A(m, -m)*B(-n, n))
asum = A(i, j) + B(i, j)
asc1 = asum(i, -i)
assert _is_equal(asc1, A(i, -i) + B(i, -i))
assert A(i, -i) == A(i, -i)()
assert canon_bp(A(i, -i) + B(-j, j) - (A(i, -i) + B(i, -i))()) == 0
assert _is_equal(A(i, j)*B(-j, k), (A(m, -j)*B(j, n))(i, k))
raises(ValueError, lambda: A(i, -i)(j, k))
def test_riemann_cyclic_replace():
Lorentz = TensorIndexType('Lorentz', dummy_fmt='L')
m0, m1, m2, m3 = tensor_indices('m:4', Lorentz)
symr = tensorsymmetry([2, 2])
R = tensorhead('R', [Lorentz]*4, [[2, 2]])
t = R(m0, m2, m1, m3)
t1 = riemann_cyclic_replace(t)
t1a = -S.One/3*R(m0, m3, m2, m1) + S.One/3*R(m0, m1, m2, m3) + Rational(2, 3)*R(m0, m2, m1, m3)
assert t1 == t1a
def test_riemann_cyclic():
Lorentz = TensorIndexType('Lorentz', dummy_fmt='L')
i, j, k, l, m, n, p, q = tensor_indices('i,j,k,l,m,n,p,q', Lorentz)
R = tensorhead('R', [Lorentz]*4, [[2, 2]])
t = R(i,j,k,l) + R(i,l,j,k) + R(i,k,l,j) - \
R(i,j,l,k) - R(i,l,k,j) - R(i,k,j,l)
t2 = t*R(-i,-j,-k,-l)
t3 = riemann_cyclic(t2)
assert t3 == 0
t = R(i,j,k,l)*(R(-i,-j,-k,-l) - 2*R(-i,-k,-j,-l))
t1 = riemann_cyclic(t)
assert t1 == 0
t = R(i,j,k,l)
t1 = riemann_cyclic(t)
assert t1 == -S(1)/3*R(i, l, j, k) + S(1)/3*R(i, k, j, l) + S(2)/3*R(i, j, k, l)
t = R(i,j,k,l)*R(-k,-l,m,n)*(R(-m,-n,-i,-j) + 2*R(-m,-j,-n,-i))
t1 = riemann_cyclic(t)
assert t1 == 0
@XFAIL
def test_div():
Lorentz = TensorIndexType('Lorentz', dummy_fmt='L')
m0,m1,m2,m3 = tensor_indices('m0:4', Lorentz)
R = tensorhead('R', [Lorentz]*4, [[2, 2]])
t = R(m0,m1,-m1,m3)
t1 = t/S(4)
assert str(t1) == '(1/4)*R(m0, L_0, -L_0, m3)'
t = t.canon_bp()
assert not t1._is_canon_bp
t1 = t*4
assert t1._is_canon_bp
t1 = t1/4
assert t1._is_canon_bp
def test_contract_metric1():
D = Symbol('D')
Lorentz = TensorIndexType('Lorentz', dim=D, dummy_fmt='L')
a, b, c, d, e = tensor_indices('a,b,c,d,e', Lorentz)
g = Lorentz.metric
p = tensorhead('p', [Lorentz], [[1]])
t = g(a, b)*p(-b)
t1 = t.contract_metric(g)
assert t1 == p(a)
A, B = tensorhead('A,B', [Lorentz]*2, [[1]*2])
# case with g with all free indices
t1 = A(a,b)*B(-b,c)*g(d, e)
t2 = t1.contract_metric(g)
assert t1 == t2
# case of g(d, -d)
t1 = A(a,b)*B(-b,c)*g(-d, d)
t2 = t1.contract_metric(g)
assert t2 == D*A(a, d)*B(-d, c)
# g with one free index
t1 = A(a,b)*B(-b,-c)*g(c, d)
t2 = t1.contract_metric(g)
assert t2 == A(a, c)*B(-c, d)
# g with both indices contracted with another tensor
t1 = A(a,b)*B(-b,-c)*g(c, -a)
t2 = t1.contract_metric(g)
assert _is_equal(t2, A(a, b)*B(-b, -a))
t1 = A(a,b)*B(-b,-c)*g(c, d)*g(-a, -d)
t2 = t1.contract_metric(g)
assert _is_equal(t2, A(a,b)*B(-b,-a))
t1 = A(a,b)*g(-a,-b)
t2 = t1.contract_metric(g)
assert _is_equal(t2, A(a, -a))
assert not t2.free
Lorentz = TensorIndexType('Lorentz', dummy_fmt='L')
a, b = tensor_indices('a,b', Lorentz)
g = Lorentz.metric
raises(ValueError, lambda: g(a, -a).contract_metric(g)) # no dim
def test_contract_metric2():
D = Symbol('D')
Lorentz = TensorIndexType('Lorentz', dim=D, dummy_fmt='L')
a, b, c, d, e, L_0 = tensor_indices('a,b,c,d,e,L_0', Lorentz)
g = Lorentz.metric
p, q = tensorhead('p,q', [Lorentz], [[1]])
t1 = g(a,b)*p(c)*p(-c)
t2 = 3*g(-a,-b)*q(c)*q(-c)
t = t1*t2
t = t.contract_metric(g)
assert t == 3*D*p(a)*p(-a)*q(b)*q(-b)
t1 = g(a,b)*p(c)*p(-c)
t2 = 3*q(-a)*q(-b)
t = t1*t2
t = t.contract_metric(g)
t = t.canon_bp()
assert t == 3*p(a)*p(-a)*q(b)*q(-b)
t1 = 2*g(a,b)*p(c)*p(-c)
t2 = - 3*g(-a,-b)*q(c)*q(-c)
t = t1*t2
t = t.contract_metric(g)
t = 6*g(a,b)*g(-a,-b)*p(c)*p(-c)*q(d)*q(-d)
t = t.contract_metric(g)
t1 = 2*g(a,b)*p(c)*p(-c)
t2 = q(-a)*q(-b) + 3*g(-a,-b)*q(c)*q(-c)
t = t1*t2
t = t.contract_metric(g)
assert t == (2 + 6*D)*p(a)*p(-a)*q(b)*q(-b)
t1 = p(a)*p(b) + p(a)*q(b) + 2*g(a,b)*p(c)*p(-c)
t2 = q(-a)*q(-b) - g(-a,-b)*q(c)*q(-c)
t = t1*t2
t = t.contract_metric(g)
t1 = (1 - 2*D)*p(a)*p(-a)*q(b)*q(-b) + p(a)*q(-a)*p(b)*q(-b)
assert canon_bp(t - t1) == 0
t = g(a,b)*g(c,d)*g(-b,-c)
t1 = t.contract_metric(g)
assert t1 == g(a, d)
t1 = g(a,b)*g(c,d) + g(a,c)*g(b,d) + g(a,d)*g(b,c)
t2 = t1.substitute_indices((a,-a),(b,-b),(c,-c),(d,-d))
t = t1*t2
t = t.contract_metric(g)
assert t.equals(3*D**2 + 6*D)
t = 2*p(a)*g(b,-b)
t1 = t.contract_metric(g)
assert t1.equals(2*D*p(a))
t = 2*p(a)*g(b,-a)
t1 = t.contract_metric(g)
assert t1 == 2*p(b)
M = Symbol('M')
t = (p(a)*p(b) + g(a, b)*M**2)*g(-a, -b) - D*M**2
t1 = t.contract_metric(g)
assert t1 == p(a)*p(-a)
A = tensorhead('A', [Lorentz]*2, [[1]*2])
t = A(a, b)*p(L_0)*g(-a, -b)
t1 = t.contract_metric(g)
assert str(t1) == 'A(L_1, -L_1)*p(L_0)' or str(t1) == 'A(-L_1, L_1)*p(L_0)'
def test_metric_contract3():
D = Symbol('D')
Spinor = TensorIndexType('Spinor', dim=D, metric=True, dummy_fmt='S')
a0,a1,a2,a3,a4 = tensor_indices('a0:5', Spinor)
C = Spinor.metric
chi, psi = tensorhead('chi,psi', [Spinor], [[1]], 1)
B = tensorhead('B', [Spinor]*2, [[1],[1]])
t = C(a0, -a0)
t1 = t.contract_metric(C)
assert t1.equals(-D)
t = C(-a0, a0)
t1 = t.contract_metric(C)
assert t1.equals(D)
t = C(a0,a1)*C(-a0,-a1)
t1 = t.contract_metric(C)
assert t1.equals(D)
t = C(a1,a0)*C(-a0,-a1)
t1 = t.contract_metric(C)
assert t1.equals(-D)
t = C(-a0,a1)*C(a0,-a1)
t1 = t.contract_metric(C)
assert t1.equals(-D)
t = C(a1,-a0)*C(a0,-a1)
t1 = t.contract_metric(C)
assert t1.equals(D)
t = C(a0,a1)*B(-a1,-a0)
t1 = t.contract_metric(C)
t1 = t1.canon_bp()
assert _is_equal(t1, B(a0, -a0))
t = C(a1,a0)*B(-a1,-a0)
t1 = t.contract_metric(C)
assert _is_equal(t1, -B(a0, -a0))
t = C(a0,-a1)*B(a1,-a0)
t1 = t.contract_metric(C)
assert _is_equal(t1, -B(a0, -a0))
t = C(-a0,a1)*B(-a1,a0)
t1 = t.contract_metric(C)
assert _is_equal(t1, -B(a0, -a0))
t = C(-a0,-a1)*B(a1,a0)
t1 = t.contract_metric(C)
assert _is_equal(t1, B(a0, -a0))
t = C(-a1, a0)*B(a1,-a0)
t1 = t.contract_metric(C)
assert _is_equal(t1, B(a0, -a0))
t = C(a0,a1)*psi(-a1)
t1 = t.contract_metric(C)
assert _is_equal(t1, psi(a0))
t = C(a1,a0)*psi(-a1)
t1 = t.contract_metric(C)
assert _is_equal(t1, -psi(a0))
t = C(a0,a1)*chi(-a0)*psi(-a1)
t1 = t.contract_metric(C)
assert _is_equal(t1, -chi(a1)*psi(-a1))
t = C(a1,a0)*chi(-a0)*psi(-a1)
t1 = t.contract_metric(C)
assert _is_equal(t1, chi(a1)*psi(-a1))
t = C(-a1,a0)*chi(-a0)*psi(a1)
t1 = t.contract_metric(C)
assert _is_equal(t1, chi(-a1)*psi(a1))
t = C(a0, -a1)*chi(-a0)*psi(a1)
t1 = t.contract_metric(C)
assert _is_equal(t1, -chi(-a1)*psi(a1))
t = C(-a0,-a1)*chi(a0)*psi(a1)
t1 = t.contract_metric(C)
assert _is_equal(t1, chi(-a1)*psi(a1))
t = C(-a1,-a0)*chi(a0)*psi(a1)
t1 = t.contract_metric(C)
assert _is_equal(t1, -chi(-a1)*psi(a1))
t = C(-a1,-a0)*B(a0,a2)*psi(a1)
t1 = t.contract_metric(C)
assert _is_equal(t1, -B(-a1,a2)*psi(a1))
t = C(a1,a0)*B(-a2,-a0)*psi(-a1)
t1 = t.contract_metric(C)
assert _is_equal(t1, B(-a2,a1)*psi(-a1))
def test_epsilon():
Lorentz = TensorIndexType('Lorentz', dim=4, dummy_fmt='L')
a, b, c, d, e = tensor_indices('a,b,c,d,e', Lorentz)
g = Lorentz.metric
epsilon = Lorentz.epsilon
p, q, r, s = tensorhead('p,q,r,s', [Lorentz], [[1]])
t = epsilon(b,a,c,d)
t1 = t.canon_bp()
assert t1 == -epsilon(a,b,c,d)
t = epsilon(c,b,d,a)
t1 = t.canon_bp()
assert t1 == epsilon(a,b,c,d)
t = epsilon(c,a,d,b)
t1 = t.canon_bp()
assert t1 == -epsilon(a,b,c,d)
t = epsilon(a,b,c,d)*p(-a)*q(-b)
t1 = t.canon_bp()
assert t1 == epsilon(c, d, a, b)*p(-a)*q(-b)
t = epsilon(c,b,d,a)*p(-a)*q(-b)
t1 = t.canon_bp()
assert t1 == epsilon(c, d, a, b)*p(-a)*q(-b)
t = epsilon(c,a,d,b)*p(-a)*q(-b)
t1 = t.canon_bp()
assert t1 == -epsilon(c, d, a, b)*p(-a)*q(-b)
t = epsilon(c,a,d,b)*p(-a)*p(-b)
t1 = t.canon_bp()
assert t1 == 0
t = epsilon(c,a,d,b)*p(-a)*q(-b) + epsilon(a,b,c,d)*p(-b)*q(-a)
t1 = t.canon_bp()
assert t1 == -2*epsilon(c, d, a, b)*p(-a)*q(-b)
# Test that epsilon can be create with a SymPy integer:
Lorentz = TensorIndexType('Lorentz', dim=Integer(4), dummy_fmt='L')
epsilon = Lorentz.epsilon
assert isinstance(epsilon, TensorHead)
def test_contract_delta1():
# see Group Theory by Cvitanovic page 9
n = Symbol('n')
Color = TensorIndexType('Color', metric=None, dim=n, dummy_fmt='C')
a, b, c, d, e, f = tensor_indices('a,b,c,d,e,f', Color)
delta = Color.delta
def idn(a, b, d, c):
assert a.is_up and d.is_up
assert not (b.is_up or c.is_up)
return delta(a, c)*delta(d, b)
def T(a, b, d, c):
assert a.is_up and d.is_up
assert not (b.is_up or c.is_up)
return delta(a, b)*delta(d, c)
def P1(a, b, c, d):
return idn(a,b,c,d) - 1/n*T(a,b,c,d)
def P2(a, b, c, d):
return 1/n*T(a,b,c,d)
t = P1(a, -b, e, -f)*P1(f, -e, d, -c)
t1 = t.contract_delta(delta)
assert canon_bp(t1 - P1(a, -b, d, -c)) == 0
t = P2(a, -b, e, -f)*P2(f, -e, d, -c)
t1 = t.contract_delta(delta)
assert t1 == P2(a, -b, d, -c)
t = P1(a, -b, e, -f)*P2(f, -e, d, -c)
t1 = t.contract_delta(delta)
assert t1 == 0
t = P1(a, -b, b, -a)
t1 = t.contract_delta(delta)
assert t1.equals(n**2 - 1)
def test_fun():
D = Symbol('D')
Lorentz = TensorIndexType('Lorentz', dim=D, dummy_fmt='L')
a,b,c,d,e = tensor_indices('a,b,c,d,e', Lorentz)
g = Lorentz.metric
p, q = tensorhead('p q', [Lorentz], [[1]])
t = q(c)*p(a)*q(b) + g(a,b)*g(c,d)*q(-d)
assert t(a,b,c) == t
assert canon_bp(t - t(b,a,c) - q(c)*p(a)*q(b) + q(c)*p(b)*q(a)) == 0
assert t(b,c,d) == q(d)*p(b)*q(c) + g(b,c)*g(d,e)*q(-e)
t1 = t.fun_eval((a,b),(b,a))
assert canon_bp(t1 - q(c)*p(b)*q(a) - g(a,b)*g(c,d)*q(-d)) == 0
# check that g_{a b; c} = 0
# example taken from L. Brewin
# "A brief introduction to Cadabra" arxiv:0903.2085
# dg_{a b c} = \partial_{a} g_{b c} is symmetric in b, c
dg = tensorhead('dg', [Lorentz]*3, [[1], [1]*2])
# gamma^a_{b c} is the Christoffel symbol
gamma = S.Half*g(a,d)*(dg(-b,-d,-c) + dg(-c,-b,-d) - dg(-d,-b,-c))
# t = g_{a b; c}
t = dg(-c,-a,-b) - g(-a,-d)*gamma(d,-b,-c) - g(-b,-d)*gamma(d,-a,-c)
t = t.contract_metric(g)
assert t == 0
t = q(c)*p(a)*q(b)
assert t(b,c,d) == q(d)*p(b)*q(c)
def test_TensorManager():
Lorentz = TensorIndexType('Lorentz', dummy_fmt='L')
LorentzH = TensorIndexType('LorentzH', dummy_fmt='LH')
i, j = tensor_indices('i,j', Lorentz)
ih, jh = tensor_indices('ih,jh', LorentzH)
p, q = tensorhead('p q', [Lorentz], [[1]])
ph, qh = tensorhead('ph qh', [LorentzH], [[1]])
Gsymbol = Symbol('Gsymbol')
GHsymbol = Symbol('GHsymbol')
TensorManager.set_comm(Gsymbol, GHsymbol, 0)
G = tensorhead('G', [Lorentz], [[1]], Gsymbol)
assert TensorManager._comm_i2symbol[G.comm] == Gsymbol
GH = tensorhead('GH', [LorentzH], [[1]], GHsymbol)
ps = G(i)*p(-i)
psh = GH(ih)*ph(-ih)
t = ps + psh
t1 = t*t
assert canon_bp(t1 - ps*ps - 2*ps*psh - psh*psh) == 0
qs = G(i)*q(-i)
qsh = GH(ih)*qh(-ih)
assert _is_equal(ps*qsh, qsh*ps)
assert not _is_equal(ps*qs, qs*ps)
n = TensorManager.comm_symbols2i(Gsymbol)
assert TensorManager.comm_i2symbol(n) == Gsymbol
assert GHsymbol in TensorManager._comm_symbols2i
raises(ValueError, lambda: TensorManager.set_comm(GHsymbol, 1, 2))
TensorManager.set_comms((Gsymbol,GHsymbol,0),(Gsymbol,1,1))
assert TensorManager.get_comm(n, 1) == TensorManager.get_comm(1, n) == 1
TensorManager.clear()
assert TensorManager.comm == [{0:0, 1:0, 2:0}, {0:0, 1:1, 2:None}, {0:0, 1:None}]
assert GHsymbol not in TensorManager._comm_symbols2i
nh = TensorManager.comm_symbols2i(GHsymbol)
assert GHsymbol in TensorManager._comm_symbols2i
def test_hash():
D = Symbol('D')
Lorentz = TensorIndexType('Lorentz', dim=D, dummy_fmt='L')
a,b,c,d,e = tensor_indices('a,b,c,d,e', Lorentz)
g = Lorentz.metric
p, q = tensorhead('p q', [Lorentz], [[1]])
p_type = p.args[1]
t1 = p(a)*q(b)
t2 = p(a)*p(b)
assert hash(t1) != hash(t2)
t3 = p(a)*p(b) + g(a,b)
t4 = p(a)*p(b) - g(a,b)
assert hash(t3) != hash(t4)
assert a.func(*a.args) == a
assert Lorentz.func(*Lorentz.args) == Lorentz
assert g.func(*g.args) == g
assert p.func(*p.args) == p
assert p_type.func(*p_type.args) == p_type
assert p(a).func(*(p(a)).args) == p(a)
assert t1.func(*t1.args) == t1
assert t2.func(*t2.args) == t2
assert t3.func(*t3.args) == t3
assert t4.func(*t4.args) == t4
assert hash(a.func(*a.args)) == hash(a)
assert hash(Lorentz.func(*Lorentz.args)) == hash(Lorentz)
assert hash(g.func(*g.args)) == hash(g)
assert hash(p.func(*p.args)) == hash(p)
assert hash(p_type.func(*p_type.args)) == hash(p_type)
assert hash(p(a).func(*(p(a)).args)) == hash(p(a))
assert hash(t1.func(*t1.args)) == hash(t1)
assert hash(t2.func(*t2.args)) == hash(t2)
assert hash(t3.func(*t3.args)) == hash(t3)
assert hash(t4.func(*t4.args)) == hash(t4)
def check_all(obj):
return all([isinstance(_, Basic) for _ in obj.args])
assert check_all(a)
assert check_all(Lorentz)
assert check_all(g)
assert check_all(p)
assert check_all(p_type)
assert check_all(p(a))
assert check_all(t1)
assert check_all(t2)
assert check_all(t3)
assert check_all(t4)
tsymmetry = tensorsymmetry([2], [1], [1, 1, 1])
assert tsymmetry.func(*tsymmetry.args) == tsymmetry
assert hash(tsymmetry.func(*tsymmetry.args)) == hash(tsymmetry)
assert check_all(tsymmetry)
### TEST VALUED TENSORS ###
def _get_valued_base_test_variables():
minkowski = Matrix((
(1, 0, 0, 0),
(0, -1, 0, 0),
(0, 0, -1, 0),
(0, 0, 0, -1),
))
Lorentz = TensorIndexType('Lorentz', dim=4)
Lorentz.data = minkowski
i0, i1, i2, i3, i4 = tensor_indices('i0:5', Lorentz)
E, px, py, pz = symbols('E px py pz')
A = tensorhead('A', [Lorentz], [[1]])
A.data = [E, px, py, pz]
B = tensorhead('B', [Lorentz], [[1]], 'Gcomm')
B.data = range(4)
AB = tensorhead("AB", [Lorentz] * 2, [[1]]*2)
AB.data = minkowski
ba_matrix = Matrix((
(1, 2, 3, 4),
(5, 6, 7, 8),
(9, 0, -1, -2),
(-3, -4, -5, -6),
))
BA = tensorhead("BA", [Lorentz] * 2, [[1]]*2)
BA.data = ba_matrix
# Let's test the diagonal metric, with inverted Minkowski metric:
LorentzD = TensorIndexType('LorentzD')
LorentzD.data = [-1, 1, 1, 1]
mu0, mu1, mu2 = tensor_indices('mu0:3', LorentzD)
C = tensorhead('C', [LorentzD], [[1]])
C.data = [E, px, py, pz]
### non-diagonal metric ###
ndm_matrix = (
(1, 1, 0,),
(1, 0, 1),
(0, 1, 0,),
)
ndm = TensorIndexType("ndm")
ndm.data = ndm_matrix
n0, n1, n2 = tensor_indices('n0:3', ndm)
NA = tensorhead('NA', [ndm], [[1]])
NA.data = range(10, 13)
NB = tensorhead('NB', [ndm]*2, [[1]]*2)
NB.data = [[i+j for j in range(10, 13)] for i in range(10, 13)]
NC = tensorhead('NC', [ndm]*3, [[1]]*3)
NC.data = [[[i+j+k for k in range(4, 7)] for j in range(1, 4)] for i in range(2, 5)]
return (A, B, AB, BA, C, Lorentz, E, px, py, pz, LorentzD, mu0, mu1, mu2, ndm, n0, n1,
n2, NA, NB, NC, minkowski, ba_matrix, ndm_matrix, i0, i1, i2, i3, i4)
@filter_warnings_decorator
def test_valued_tensor_iter():
(A, B, AB, BA, C, Lorentz, E, px, py, pz, LorentzD, mu0, mu1, mu2, ndm, n0, n1,
n2, NA, NB, NC, minkowski, ba_matrix, ndm_matrix, i0, i1, i2, i3, i4) = _get_valued_base_test_variables()
# iteration on VTensorHead
assert list(A) == [E, px, py, pz]
assert list(ba_matrix) == list(BA)
# iteration on VTensMul
assert list(A(i1)) == [E, px, py, pz]
assert list(BA(i1, i2)) == list(ba_matrix)
assert list(3 * BA(i1, i2)) == [3 * i for i in list(ba_matrix)]
assert list(-5 * BA(i1, i2)) == [-5 * i for i in list(ba_matrix)]
# iteration on VTensAdd
# A(i1) + A(i1)
assert list(A(i1) + A(i1)) == [2*E, 2*px, 2*py, 2*pz]
assert BA(i1, i2) - BA(i1, i2) == 0
assert list(BA(i1, i2) - 2 * BA(i1, i2)) == [-i for i in list(ba_matrix)]
@filter_warnings_decorator
def test_valued_tensor_covariant_contravariant_elements():
(A, B, AB, BA, C, Lorentz, E, px, py, pz, LorentzD, mu0, mu1, mu2, ndm, n0, n1,
n2, NA, NB, NC, minkowski, ba_matrix, ndm_matrix, i0, i1, i2, i3, i4) = _get_valued_base_test_variables()
assert A(-i0)[0] == A(i0)[0]
assert A(-i0)[1] == -A(i0)[1]
assert AB(i0, i1)[1, 1] == -1
assert AB(i0, -i1)[1, 1] == 1
assert AB(-i0, -i1)[1, 1] == -1
assert AB(-i0, i1)[1, 1] == 1
@filter_warnings_decorator
def test_valued_tensor_get_matrix():
(A, B, AB, BA, C, Lorentz, E, px, py, pz, LorentzD, mu0, mu1, mu2, ndm, n0, n1,
n2, NA, NB, NC, minkowski, ba_matrix, ndm_matrix, i0, i1, i2, i3, i4) = _get_valued_base_test_variables()
matab = AB(i0, i1).get_matrix()
assert matab == Matrix([
[1, 0, 0, 0],
[0, -1, 0, 0],
[0, 0, -1, 0],
[0, 0, 0, -1],
])
# when alternating contravariant/covariant with [1, -1, -1, -1] metric
# it becomes the identity matrix:
assert AB(i0, -i1).get_matrix() == eye(4)
# covariant and contravariant forms:
assert A(i0).get_matrix() == Matrix([E, px, py, pz])
assert A(-i0).get_matrix() == Matrix([E, -px, -py, -pz])
@filter_warnings_decorator
def test_valued_tensor_contraction():
(A, B, AB, BA, C, Lorentz, E, px, py, pz, LorentzD, mu0, mu1, mu2, ndm, n0, n1,
n2, NA, NB, NC, minkowski, ba_matrix, ndm_matrix, i0, i1, i2, i3, i4) = _get_valued_base_test_variables()
assert (A(i0) * A(-i0)).data == E ** 2 - px ** 2 - py ** 2 - pz ** 2
assert (A(i0) * A(-i0)).data == A ** 2
assert (A(i0) * A(-i0)).data == A(i0) ** 2
assert (A(i0) * B(-i0)).data == -px - 2 * py - 3 * pz
for i in range(4):
for j in range(4):
assert (A(i0) * B(-i1))[i, j] == [E, px, py, pz][i] * [0, -1, -2, -3][j]
# test contraction on the alternative Minkowski metric: [-1, 1, 1, 1]
assert (C(mu0) * C(-mu0)).data == -E ** 2 + px ** 2 + py ** 2 + pz ** 2
contrexp = A(i0) * AB(i1, -i0)
assert A(i0).rank == 1
assert AB(i1, -i0).rank == 2
assert contrexp.rank == 1
for i in range(4):
assert contrexp[i] == [E, px, py, pz][i]
@filter_warnings_decorator
def test_valued_tensor_self_contraction():
(A, B, AB, BA, C, Lorentz, E, px, py, pz, LorentzD, mu0, mu1, mu2, ndm, n0, n1,
n2, NA, NB, NC, minkowski, ba_matrix, ndm_matrix, i0, i1, i2, i3, i4) = _get_valued_base_test_variables()
assert AB(i0, -i0).data == 4
assert BA(i0, -i0).data == 2
@filter_warnings_decorator
def test_valued_tensor_pow():
(A, B, AB, BA, C, Lorentz, E, px, py, pz, LorentzD, mu0, mu1, mu2, ndm, n0, n1,
n2, NA, NB, NC, minkowski, ba_matrix, ndm_matrix, i0, i1, i2, i3, i4) = _get_valued_base_test_variables()
assert C**2 == -E**2 + px**2 + py**2 + pz**2
assert C**1 == sqrt(-E**2 + px**2 + py**2 + pz**2)
assert C(mu0)**2 == C**2
assert C(mu0)**1 == C**1
@filter_warnings_decorator
def test_valued_tensor_expressions():
(A, B, AB, BA, C, Lorentz, E, px, py, pz, LorentzD, mu0, mu1, mu2, ndm, n0, n1,
n2, NA, NB, NC, minkowski, ba_matrix, ndm_matrix, i0, i1, i2, i3, i4) = _get_valued_base_test_variables()
x1, x2, x3 = symbols('x1:4')
# test coefficient in contraction:
rank2coeff = x1 * A(i3) * B(i2)
assert rank2coeff[1, 1] == x1 * px
assert rank2coeff[3, 3] == 3 * pz * x1
coeff_expr = ((x1 * A(i4)) * (B(-i4) / x2)).data
assert coeff_expr.expand() == -px*x1/x2 - 2*py*x1/x2 - 3*pz*x1/x2
add_expr = A(i0) + B(i0)
assert add_expr[0] == E
assert add_expr[1] == px + 1
assert add_expr[2] == py + 2
assert add_expr[3] == pz + 3
sub_expr = A(i0) - B(i0)
assert sub_expr[0] == E
assert sub_expr[1] == px - 1
assert sub_expr[2] == py - 2
assert sub_expr[3] == pz - 3
assert (add_expr * B(-i0)).data == -px - 2*py - 3*pz - 14
expr1 = x1*A(i0) + x2*B(i0)
expr2 = expr1 * B(i1) * (-4)
expr3 = expr2 + 3*x3*AB(i0, i1)
expr4 = expr3 / 2
assert expr4 * 2 == expr3
expr5 = (expr4 * BA(-i1, -i0))
assert expr5.data.expand() == 28*E*x1 + 12*px*x1 + 20*py*x1 + 28*pz*x1 + 136*x2 + 3*x3
@filter_warnings_decorator
def test_valued_tensor_add_scalar():
(A, B, AB, BA, C, Lorentz, E, px, py, pz, LorentzD, mu0, mu1, mu2, ndm, n0, n1,
n2, NA, NB, NC, minkowski, ba_matrix, ndm_matrix, i0, i1, i2, i3, i4) = _get_valued_base_test_variables()
# one scalar summand after the contracted tensor
expr1 = A(i0)*A(-i0) - (E**2 - px**2 - py**2 - pz**2)
assert expr1.data == 0
# multiple scalar summands in front of the contracted tensor
expr2 = E**2 - px**2 - py**2 - pz**2 - A(i0)*A(-i0)
assert expr2.data == 0
# multiple scalar summands after the contracted tensor
expr3 = A(i0)*A(-i0) - E**2 + px**2 + py**2 + pz**2
assert expr3.data == 0
# multiple scalar summands and multiple tensors
expr4 = C(mu0)*C(-mu0) + 2*E**2 - 2*px**2 - 2*py**2 - 2*pz**2 - A(i0)*A(-i0)
assert expr4.data == 0
@filter_warnings_decorator
def test_noncommuting_components():
(A, B, AB, BA, C, Lorentz, E, px, py, pz, LorentzD, mu0, mu1, mu2, ndm, n0, n1,
n2, NA, NB, NC, minkowski, ba_matrix, ndm_matrix, i0, i1, i2, i3, i4) = _get_valued_base_test_variables()
euclid = TensorIndexType('Euclidean')
euclid.data = [1, 1]
i1, i2, i3 = tensor_indices('i1:4', euclid)
a, b, c, d = symbols('a b c d', commutative=False)
V1 = tensorhead('V1', [euclid] * 2, [[1]]*2)
V1.data = [[a, b], (c, d)]
V2 = tensorhead('V2', [euclid] * 2, [[1]]*2)
V2.data = [[a, c], [b, d]]
vtp = V1(i1, i2) * V2(-i2, -i1)
assert vtp.data == a**2 + b**2 + c**2 + d**2
assert vtp.data != a**2 + 2*b*c + d**2
vtp2 = V1(i1, i2)*V1(-i2, -i1)
assert vtp2.data == a**2 + b*c + c*b + d**2
assert vtp2.data != a**2 + 2*b*c + d**2
Vc = (b * V1(i1, -i1)).data
assert Vc.expand() == b * a + b * d
@filter_warnings_decorator
def test_valued_non_diagonal_metric():
(A, B, AB, BA, C, Lorentz, E, px, py, pz, LorentzD, mu0, mu1, mu2, ndm, n0, n1,
n2, NA, NB, NC, minkowski, ba_matrix, ndm_matrix, i0, i1, i2, i3, i4) = _get_valued_base_test_variables()
mmatrix = Matrix(ndm_matrix)
assert (NA(n0)*NA(-n0)).data == (NA(n0).get_matrix().T * mmatrix * NA(n0).get_matrix())[0, 0]
@filter_warnings_decorator
def test_valued_assign_numpy_ndarray():
(A, B, AB, BA, C, Lorentz, E, px, py, pz, LorentzD, mu0, mu1, mu2, ndm, n0, n1,
n2, NA, NB, NC, minkowski, ba_matrix, ndm_matrix, i0, i1, i2, i3, i4) = _get_valued_base_test_variables()
# this is needed to make sure that a numpy.ndarray can be assigned to a
# tensor.
arr = [E+1, px-1, py, pz]
A.data = Array(arr)
for i in range(4):
assert A(i0).data[i] == arr[i]
qx, qy, qz = symbols('qx qy qz')
A(-i0).data = Array([E, qx, qy, qz])
for i in range(4):
assert A(i0).data[i] == [E, -qx, -qy, -qz][i]
assert A.data[i] == [E, -qx, -qy, -qz][i]
# test on multi-indexed tensors.
random_4x4_data = [[(i**3-3*i**2)%(j+7) for i in range(4)] for j in range(4)]
AB(-i0, -i1).data = random_4x4_data
for i in range(4):
for j in range(4):
assert AB(i0, i1).data[i, j] == random_4x4_data[i][j]*(-1 if i else 1)*(-1 if j else 1)
assert AB(-i0, i1).data[i, j] == random_4x4_data[i][j]*(-1 if j else 1)
assert AB(i0, -i1).data[i, j] == random_4x4_data[i][j]*(-1 if i else 1)
assert AB(-i0, -i1).data[i, j] == random_4x4_data[i][j]
AB(-i0, i1).data = random_4x4_data
for i in range(4):
for j in range(4):
assert AB(i0, i1).data[i, j] == random_4x4_data[i][j]*(-1 if i else 1)
assert AB(-i0, i1).data[i, j] == random_4x4_data[i][j]
assert AB(i0, -i1).data[i, j] == random_4x4_data[i][j]*(-1 if i else 1)*(-1 if j else 1)
assert AB(-i0, -i1).data[i, j] == random_4x4_data[i][j]*(-1 if j else 1)
@filter_warnings_decorator
def test_valued_metric_inverse():
(A, B, AB, BA, C, Lorentz, E, px, py, pz, LorentzD, mu0, mu1, mu2, ndm, n0, n1,
n2, NA, NB, NC, minkowski, ba_matrix, ndm_matrix, i0, i1, i2, i3, i4) = _get_valued_base_test_variables()
# let's assign some fancy matrix, just to verify it:
# (this has no physical sense, it's just testing sympy);
# it is symmetrical:
md = [[2, 2, 2, 1], [2, 3, 1, 0], [2, 1, 2, 3], [1, 0, 3, 2]]
Lorentz.data = md
m = Matrix(md)
metric = Lorentz.metric
minv = m.inv()
meye = eye(4)
# the Kronecker Delta:
KD = Lorentz.get_kronecker_delta()
for i in range(4):
for j in range(4):
assert metric(i0, i1).data[i, j] == m[i, j]
assert metric(-i0, -i1).data[i, j] == minv[i, j]
assert metric(i0, -i1).data[i, j] == meye[i, j]
assert metric(-i0, i1).data[i, j] == meye[i, j]
assert metric(i0, i1)[i, j] == m[i, j]
assert metric(-i0, -i1)[i, j] == minv[i, j]
assert metric(i0, -i1)[i, j] == meye[i, j]
assert metric(-i0, i1)[i, j] == meye[i, j]
assert KD(i0, -i1)[i, j] == meye[i, j]
@filter_warnings_decorator
def test_valued_canon_bp_swapaxes():
(A, B, AB, BA, C, Lorentz, E, px, py, pz, LorentzD, mu0, mu1, mu2, ndm, n0, n1,
n2, NA, NB, NC, minkowski, ba_matrix, ndm_matrix, i0, i1, i2, i3, i4) = _get_valued_base_test_variables()
e1 = A(i1)*A(i0)
e2 = e1.canon_bp()
assert e2 == A(i0)*A(i1)
for i in range(4):
for j in range(4):
assert e1[i, j] == e2[j, i]
o1 = B(i2)*A(i1)*B(i0)
o2 = o1.canon_bp()
for i in range(4):
for j in range(4):
for k in range(4):
assert o1[i, j, k] == o2[j, i, k]
def test_pprint():
Lorentz = TensorIndexType('Lorentz')
A = tensorhead('A', [Lorentz], [[1]])
assert pretty(A) == "A(Lorentz)"
@filter_warnings_decorator
def test_valued_components_with_wrong_symmetry():
IT = TensorIndexType('IT', dim=3)
i0, i1, i2, i3 = tensor_indices('i0:4', IT)
IT.data = [1, 1, 1]
A_nosym = tensorhead('A', [IT]*2, [[1]]*2)
A_sym = tensorhead('A', [IT]*2, [[1]*2])
A_antisym = tensorhead('A', [IT]*2, [[2]])
mat_nosym = Matrix([[1,2,3],[4,5,6],[7,8,9]])
mat_sym = mat_nosym + mat_nosym.T
mat_antisym = mat_nosym - mat_nosym.T
A_nosym.data = mat_nosym
A_nosym.data = mat_sym
A_nosym.data = mat_antisym
def assign(A, dat):
A.data = dat
A_sym.data = mat_sym
raises(ValueError, lambda: assign(A_sym, mat_nosym))
raises(ValueError, lambda: assign(A_sym, mat_antisym))
A_antisym.data = mat_antisym
raises(ValueError, lambda: assign(A_antisym, mat_sym))
raises(ValueError, lambda: assign(A_antisym, mat_nosym))
A_sym.data = [[0, 0, 0], [0, 0, 0], [0, 0, 0]]
A_antisym.data = [[0, 0, 0], [0, 0, 0], [0, 0, 0]]
@filter_warnings_decorator
def test_issue_10972_TensMul_data():
Lorentz = TensorIndexType('Lorentz', metric=False, dummy_fmt='i', dim=2)
Lorentz.data = [-1, 1]
mu, nu, alpha, beta = tensor_indices('\\mu, \\nu, \\alpha, \\beta',
Lorentz)
Vec = TensorType([Lorentz], tensorsymmetry([1]))
A2 = TensorType([Lorentz] * 2, tensorsymmetry([2]))
u = Vec('u')
u.data = [1, 0]
F = A2('F')
F.data = [[0, 1],
[-1, 0]]
mul_1 = F(mu, alpha) * u(-alpha) * F(nu, beta) * u(-beta)
assert (mul_1.data == Array([[0, 0], [0, 1]]))
mul_2 = F(mu, alpha) * F(nu, beta) * u(-alpha) * u(-beta)
assert (mul_2.data == mul_1.data)
assert ((mul_1 + mul_1).data == 2 * mul_1.data)
@filter_warnings_decorator
def test_TensMul_data():
Lorentz = TensorIndexType('Lorentz', metric=False, dummy_fmt='L', dim=4)
Lorentz.data = [-1, 1, 1, 1]
mu, nu, alpha, beta = tensor_indices('\\mu, \\nu, \\alpha, \\beta',
Lorentz)
Vec = TensorType([Lorentz], tensorsymmetry([1]))
A2 = TensorType([Lorentz] * 2, tensorsymmetry([2]))
u = Vec('u')
u.data = [1, 0, 0, 0]
F = A2('F')
Ex, Ey, Ez, Bx, By, Bz = symbols('E_x E_y E_z B_x B_y B_z')
F.data = [
[0, Ex, Ey, Ez],
[-Ex, 0, Bz, -By],
[-Ey, -Bz, 0, Bx],
[-Ez, By, -Bx, 0]]
E = F(mu, nu) * u(-nu)
assert ((E(mu) * E(nu)).data ==
Array([[0, 0, 0, 0],
[0, Ex ** 2, Ex * Ey, Ex * Ez],
[0, Ex * Ey, Ey ** 2, Ey * Ez],
[0, Ex * Ez, Ey * Ez, Ez ** 2]])
)
assert ((E(mu) * E(nu)).canon_bp().data == (E(mu) * E(nu)).data)
assert ((F(mu, alpha) * F(beta, nu) * u(-alpha) * u(-beta)).data ==
- (E(mu) * E(nu)).data
)
assert ((F(alpha, mu) * F(beta, nu) * u(-alpha) * u(-beta)).data ==
(E(mu) * E(nu)).data
)
S2 = TensorType([Lorentz] * 2, tensorsymmetry([1] * 2))
g = S2('g')
g.data = Lorentz.data
# tensor 'perp' is orthogonal to vector 'u'
perp = u(mu) * u(nu) + g(mu, nu)
mul_1 = u(-mu) * perp(mu, nu)
assert (mul_1.data == Array([0, 0, 0, 0]))
mul_2 = u(-mu) * perp(mu, alpha) * perp(nu, beta)
assert (mul_2.data == Array.zeros(4, 4, 4))
Fperp = perp(mu, alpha) * perp(nu, beta) * F(-alpha, -beta)
assert (Fperp.data[0, :] == Array([0, 0, 0, 0]))
assert (Fperp.data[:, 0] == Array([0, 0, 0, 0]))
mul_3 = u(-mu) * Fperp(mu, nu)
assert (mul_3.data == Array([0, 0, 0, 0]))
@filter_warnings_decorator
def test_issue_11020_TensAdd_data():
Lorentz = TensorIndexType('Lorentz', metric=False, dummy_fmt='i', dim=2)
Lorentz.data = [-1, 1]
a, b, c, d = tensor_indices('a, b, c, d', Lorentz)
i0, i1 = tensor_indices('i_0:2', Lorentz)
Vec = TensorType([Lorentz], tensorsymmetry([1]))
S2 = TensorType([Lorentz] * 2, tensorsymmetry([1] * 2))
# metric tensor
g = S2('g')
g.data = Lorentz.data
u = Vec('u')
u.data = [1, 0]
add_1 = g(b, c) * g(d, i0) * u(-i0) - g(b, c) * u(d)
assert (add_1.data == Array.zeros(2, 2, 2))
# Now let us replace index `d` with `a`:
add_2 = g(b, c) * g(a, i0) * u(-i0) - g(b, c) * u(a)
assert (add_2.data == Array.zeros(2, 2, 2))
# some more tests
# perp is tensor orthogonal to u^\mu
perp = u(a) * u(b) + g(a, b)
mul_1 = u(-a) * perp(a, b)
assert (mul_1.data == Array([0, 0]))
mul_2 = u(-c) * perp(c, a) * perp(d, b)
assert (mul_2.data == Array.zeros(2, 2, 2))
def test_index_iteration():
L = TensorIndexType("Lorentz", dummy_fmt="L")
i0,i1,i2,i3,i4 = tensor_indices('i0:5', L)
L0 = tensor_indices('L_0', L)
L1 = tensor_indices('L_1', L)
A = tensorhead("A", [L, L], [[1], [1]])
B = tensorhead("B", [L, L], [[1, 1]])
C = tensorhead("C", [L], [[1]])
e1 = A(i0, i2)
e2 = A(i0, -i0)
e3 = A(i0, i1)*B(i2, i3)
e4 = A(i0, i1)*B(i2, -i1)
e5 = A(i0, i1)*B(-i0, -i1)
e6 = e1 + e4
assert list(e1._iterate_free_indices) == [(i0, (1, 0)), (i2, (1, 1))]
assert list(e1._iterate_dummy_indices) == []
assert list(e1._iterate_indices) == [(i0, (1, 0)), (i2, (1, 1))]
assert list(e2._iterate_free_indices) == []
assert list(e2._iterate_dummy_indices) == [(L0, (1, 0)), (-L0, (1, 1))]
assert list(e2._iterate_indices) == [(L0, (1, 0)), (-L0, (1, 1))]
assert list(e3._iterate_free_indices) == [(i0, (0, 1, 0)), (i1, (0, 1, 1)), (i2, (1, 1, 0)), (i3, (1, 1, 1))]
assert list(e3._iterate_dummy_indices) == []
assert list(e3._iterate_indices) == [(i0, (0, 1, 0)), (i1, (0, 1, 1)), (i2, (1, 1, 0)), (i3, (1, 1, 1))]
assert list(e4._iterate_free_indices) == [(i0, (0, 1, 0)), (i2, (1, 1, 0))]
assert list(e4._iterate_dummy_indices) == [(L0, (0, 1, 1)), (-L0, (1, 1, 1))]
assert list(e4._iterate_indices) == [(i0, (0, 1, 0)), (L0, (0, 1, 1)), (i2, (1, 1, 0)), (-L0, (1, 1, 1))]
assert list(e5._iterate_free_indices) == []
assert list(e5._iterate_dummy_indices) == [(L0, (0, 1, 0)), (L1, (0, 1, 1)), (-L0, (1, 1, 0)), (-L1, (1, 1, 1))]
assert list(e5._iterate_indices) == [(L0, (0, 1, 0)), (L1, (0, 1, 1)), (-L0, (1, 1, 0)), (-L1, (1, 1, 1))]
assert list(e6._iterate_free_indices) == [(i0, (0, 1, 0)), (i2, (0, 1, 1)), (i0, (1, 0, 1, 0)), (i2, (1, 1, 1, 0))]
assert list(e6._iterate_dummy_indices) == [(L0, (1, 0, 1, 1)), (-L0, (1, 1, 1, 1))]
assert list(e6._iterate_indices) == [(i0, (0, 1, 0)), (i2, (0, 1, 1)), (i0, (1, 0, 1, 0)), (L0, (1, 0, 1, 1)), (i2, (1, 1, 1, 0)), (-L0, (1, 1, 1, 1))]
assert e1.get_indices() == [i0, i2]
assert e1.get_free_indices() == [i0, i2]
assert e2.get_indices() == [L0, -L0]
assert e2.get_free_indices() == []
assert e3.get_indices() == [i0, i1, i2, i3]
assert e3.get_free_indices() == [i0, i1, i2, i3]
assert e4.get_indices() == [i0, L0, i2, -L0]
assert e4.get_free_indices() == [i0, i2]
assert e5.get_indices() == [L0, L1, -L0, -L1]
assert e5.get_free_indices() == []
def test_tensor_expand():
L = TensorIndexType("L")
i, j, k = tensor_indices("i j k", L)
i0 = tensor_indices("i0", L)
L_0 = TensorIndex("L_0", L)
L_1 = TensorIndex("L_1", L)
A, B, C, D = tensorhead("A B C D", [L], [[1]])
H = tensorhead("H", [L, L], [[1], [1]])
assert isinstance(Add(A(i), B(i)), TensAdd)
assert isinstance(expand(A(i)+B(i)), TensAdd)
expr = A(i)*(A(-i)+B(-i))
assert expr.args == (A(L_0), A(-L_0) + B(-L_0))
assert expr != A(i)*A(-i) + A(i)*B(-i)
assert expr.expand() == A(i)*A(-i) + A(i)*B(-i)
assert str(expr) == "A(L_0)*(A(-L_0) + B(-L_0))"
expr = A(i)*A(j) + A(i)*B(j)
assert str(expr) == "A(i)*A(j) + A(i)*B(j)"
expr = A(-i)*(A(i)*A(j) + A(i)*B(j)*C(k)*C(-k))
assert expr != A(-i)*A(i)*A(j) + A(-i)*A(i)*B(j)*C(k)*C(-k)
assert expr.expand() == A(-i)*A(i)*A(j) + A(-i)*A(i)*B(j)*C(k)*C(-k)
assert str(expr) == "A(-L_0)*(A(L_0)*A(j) + A(L_0)*B(j)*C(L_1)*C(-L_1))"
assert str(expr.canon_bp()) == 'A(L_0)*A(-L_0)*B(j)*C(L_1)*C(-L_1) + A(j)*A(L_0)*A(-L_0)'
expr = A(-i)*(2*A(i)*A(j) + A(i)*B(j))
assert expr.expand() == 2*A(-i)*A(i)*A(j) + A(-i)*A(i)*B(j)
expr = 2*A(i)*A(-i)
assert expr.coeff == 2
expr = A(i)*(B(j)*C(k) + C(j)*(A(k) + D(k)))
assert str(expr) == "A(i)*(B(j)*C(k) + C(j)*(A(k) + D(k)))"
assert str(expr.expand()) == "A(i)*B(j)*C(k) + A(i)*C(j)*A(k) + A(i)*C(j)*D(k)"
assert isinstance(TensMul(3), TensMul)
tm = TensMul(3).doit()
assert tm == 3
assert isinstance(tm, Integer)
p1 = B(j)*B(-j) + B(j)*C(-j)
p2 = C(-i)*p1
p3 = A(i)*p2
expr = A(i)*(B(-i) + C(-i)*(B(j)*B(-j) + B(j)*C(-j)))
assert expr.expand() == A(i)*B(-i) + A(i)*C(-i)*B(j)*B(-j) + A(i)*C(-i)*B(j)*C(-j)
expr = C(-i)*(B(j)*B(-j) + B(j)*C(-j))
assert expr.expand() == C(-i)*B(j)*B(-j) + C(-i)*B(j)*C(-j)
def test_tensor_alternative_construction():
L = TensorIndexType("L")
i0, i1, i2, i3 = tensor_indices('i0:4', L)
A = tensorhead("A", [L], [[1]])
x, y = symbols("x y")
assert A(i0) == A(Symbol("i0"))
assert A(-i0) == A(-Symbol("i0"))
raises(TypeError, lambda: A(x+y))
raises(ValueError, lambda: A(2*x))
def test_tensor_replacement():
L = TensorIndexType("L")
L2 = TensorIndexType("L2", dim=2)
i, j, k, l = tensor_indices("i j k l", L)
i0 = tensor_indices("i0", L)
A, B, C, D = tensorhead("A B C D", [L], [[1]])
H = tensorhead("H", [L, L], [[1], [1]])
K = tensorhead("K", [L, L, L, L], [[1], [1], [1], [1]])
expr = H(i, j)
repl = {H(i,-j): [[1,2],[3,4]], L: diag(1, -1)}
assert expr._extract_data(repl) == ([i, j], Array([[1, -2], [3, -4]]))
assert expr.replace_with_arrays(repl, [i, j]) == Array([[1, -2], [3, -4]])
assert expr.replace_with_arrays(repl, [i, -j]) == Array([[1, 2], [3, 4]])
assert expr.replace_with_arrays(repl, [-i, j]) == Array([[1, -2], [-3, 4]])
assert expr.replace_with_arrays(repl, [-i, -j]) == Array([[1, 2], [-3, -4]])
assert expr.replace_with_arrays(repl, [j, i]) == Array([[1, 3], [-2, -4]])
assert expr.replace_with_arrays(repl, [j, -i]) == Array([[1, -3], [-2, 4]])
assert expr.replace_with_arrays(repl, [-j, i]) == Array([[1, 3], [2, 4]])
assert expr.replace_with_arrays(repl, [-j, -i]) == Array([[1, -3], [2, -4]])
expr = H(i,j)
repl = {H(i,j): [[1,2],[3,4]], L: diag(1, -1)}
assert expr._extract_data(repl) == ([i, j], Array([[1, 2], [3, 4]]))
assert expr.replace_with_arrays(repl, [i, j]) == Array([[1, 2], [3, 4]])
assert expr.replace_with_arrays(repl, [i, -j]) == Array([[1, -2], [3, -4]])
assert expr.replace_with_arrays(repl, [-i, j]) == Array([[1, 2], [-3, -4]])
assert expr.replace_with_arrays(repl, [-i, -j]) == Array([[1, -2], [-3, 4]])
assert expr.replace_with_arrays(repl, [j, i]) == Array([[1, 3], [2, 4]])
assert expr.replace_with_arrays(repl, [j, -i]) == Array([[1, -3], [2, -4]])
assert expr.replace_with_arrays(repl, [-j, i]) == Array([[1, 3], [-2, -4]])
assert expr.replace_with_arrays(repl, [-j, -i]) == Array([[1, -3], [-2, 4]])
# Not the same indices:
expr = H(i,k)
repl = {H(i,j): [[1,2],[3,4]], L: diag(1, -1)}
assert expr._extract_data(repl) == ([i, k], Array([[1, 2], [3, 4]]))
expr = A(i)*A(-i)
repl = {A(i): [1,2], L: diag(1, -1)}
assert expr._extract_data(repl) == ([], -3)
assert expr.replace_with_arrays(repl, []) == -3
expr = K(i, j, -j, k)*A(-i)*A(-k)
repl = {A(i): [1, 2], K(i,j,k,l): Array([1]*2**4).reshape(2,2,2,2), L: diag(1, -1)}
assert expr._extract_data(repl)
expr = H(j, k)
repl = {H(i,j): [[1,2],[3,4]], L: diag(1, -1)}
raises(ValueError, lambda: expr._extract_data(repl))
expr = A(i)
repl = {B(i): [1, 2]}
raises(ValueError, lambda: expr._extract_data(repl))
expr = A(i)
repl = {A(i): [[1, 2], [3, 4]]}
raises(ValueError, lambda: expr._extract_data(repl))
# TensAdd:
expr = A(k)*H(i, j) + B(k)*H(i, j)
repl = {A(k): [1], B(k): [1], H(i, j): [[1, 2],[3,4]], L:diag(1,1)}
assert expr._extract_data(repl) == ([k, i, j], Array([[[2, 4], [6, 8]]]))
assert expr.replace_with_arrays(repl, [k, i, j]) == Array([[[2, 4], [6, 8]]])
assert expr.replace_with_arrays(repl, [k, j, i]) == Array([[[2, 6], [4, 8]]])
expr = A(k)*A(-k) + 100
repl = {A(k): [2, 3], L: diag(1, 1)}
assert expr.replace_with_arrays(repl, []) == 113
## Symmetrization:
expr = H(i, j) + H(j, i)
repl = {H(i, j): [[1, 2], [3, 4]]}
assert expr._extract_data(repl) == ([i, j], Array([[2, 5], [5, 8]]))
assert expr.replace_with_arrays(repl, [i, j]) == Array([[2, 5], [5, 8]])
assert expr.replace_with_arrays(repl, [j, i]) == Array([[2, 5], [5, 8]])
## Anti-symmetrization:
expr = H(i, j) - H(j, i)
repl = {H(i, j): [[1, 2], [3, 4]]}
assert expr.replace_with_arrays(repl, [i, j]) == Array([[0, -1], [1, 0]])
assert expr.replace_with_arrays(repl, [j, i]) == Array([[0, 1], [-1, 0]])
# Tensors with contractions in replacements:
expr = K(i, j, k, -k)
repl = {K(i, j, k, -k): [[1, 2], [3, 4]]}
assert expr._extract_data(repl) == ([i, j], Array([[1, 2], [3, 4]]))
expr = H(i, -i)
repl = {H(i, -i): 42}
assert expr._extract_data(repl) == ([], 42)
# Replace with array, raise exception if indices are not compatible:
expr = A(i)*A(j)
repl = {A(i): [1, 2]}
raises(ValueError, lambda: expr.replace_with_arrays(repl, [j]))
# Raise exception if array dimension is not compatible:
expr = A(i)
repl = {A(i): [[1, 2]]}
raises(ValueError, lambda: expr.replace_with_arrays(repl, [i]))
# TensorIndexType with dimension, wrong dimension in replacement array:
u1, u2, u3 = tensor_indices("u1:4", L2)
U = tensorhead("U", [L2], [[1]])
expr = U(u1)*U(-u2)
repl = {U(u1): [[1]]}
raises(ValueError, lambda: expr.replace_with_arrays(repl, [u1, -u2]))
def test_rewrite_tensor_to_Indexed():
L = TensorIndexType("L", dim=4)
A = tensorhead("A", [L, L, L, L], [[1], [1], [1], [1]])
B = tensorhead("B", [L], [[1]])
i0, i1, i2, i3 = symbols("i0:4")
L_0, L_1 = symbols("L_0:2")
a1 = A(i0, i1, i2, i3)
assert a1.rewrite(Indexed) == Indexed(Symbol("A"), i0, i1, i2, i3)
a2 = A(i0, -i0, i2, i3)
assert a2.rewrite(Indexed) == Sum(Indexed(Symbol("A"), L_0, L_0, i2, i3), (L_0, 0, 3))
a3 = a2 + A(i2, i3, i0, -i0)
assert a3.rewrite(Indexed) == \
Sum(Indexed(Symbol("A"), L_0, L_0, i2, i3), (L_0, 0, 3)) +\
Sum(Indexed(Symbol("A"), i2, i3, L_0, L_0), (L_0, 0, 3))
b1 = B(-i0)*a1
assert b1.rewrite(Indexed) == Sum(Indexed(Symbol("B"), L_0)*Indexed(Symbol("A"), L_0, i1, i2, i3), (L_0, 0, 3))
b2 = B(-i3)*a2
assert b2.rewrite(Indexed) == Sum(Indexed(Symbol("B"), L_1)*Indexed(Symbol("A"), L_0, L_0, i2, L_1), (L_0, 0, 3), (L_1, 0, 3))
|
52fdf91969e18c9b2134acfc27dab41c6c7a01cf8ff1c86963790c362aa31ebd
|
import random
from sympy import (
Abs, Add, E, Float, I, Integer, Max, Min, N, Poly, Pow, PurePoly, Rational,
S, Symbol, cos, exp, expand_mul, oo, pi, signsimp, simplify, sin, sqrt, symbols,
sympify, trigsimp, tan, sstr, diff, Function)
from sympy.matrices.matrices import (ShapeError, MatrixError,
NonSquareMatrixError, DeferredVector, _find_reasonable_pivot_naive,
_simplify)
from sympy.matrices import (
GramSchmidt, ImmutableMatrix, ImmutableSparseMatrix, Matrix,
SparseMatrix, casoratian, diag, eye, hessian,
matrix_multiply_elementwise, ones, randMatrix, rot_axis1, rot_axis2,
rot_axis3, wronskian, zeros, MutableDenseMatrix, ImmutableDenseMatrix)
from sympy.core.compatibility import long, iterable, range, Hashable
from sympy.core import Tuple
from sympy.utilities.iterables import flatten, capture
from sympy.utilities.pytest import raises, XFAIL, slow, skip, warns_deprecated_sympy
from sympy.solvers import solve
from sympy.assumptions import Q
from sympy.tensor.array import Array
from sympy.matrices.expressions import MatPow
from sympy.abc import a, b, c, d, x, y, z, t
# don't re-order this list
classes = (Matrix, SparseMatrix, ImmutableMatrix, ImmutableSparseMatrix)
def test_args():
for c, cls in enumerate(classes):
m = cls.zeros(3, 2)
# all should give back the same type of arguments, e.g. ints for shape
assert m.shape == (3, 2) and all(type(i) is int for i in m.shape)
assert m.rows == 3 and type(m.rows) is int
assert m.cols == 2 and type(m.cols) is int
if not c % 2:
assert type(m._mat) in (list, tuple, Tuple)
else:
assert type(m._smat) is dict
def test_division():
v = Matrix(1, 2, [x, y])
assert v.__div__(z) == Matrix(1, 2, [x/z, y/z])
assert v.__truediv__(z) == Matrix(1, 2, [x/z, y/z])
assert v/z == Matrix(1, 2, [x/z, y/z])
def test_sum():
m = Matrix([[1, 2, 3], [x, y, x], [2*y, -50, z*x]])
assert m + m == Matrix([[2, 4, 6], [2*x, 2*y, 2*x], [4*y, -100, 2*z*x]])
n = Matrix(1, 2, [1, 2])
raises(ShapeError, lambda: m + n)
def test_abs():
m = Matrix(1, 2, [-3, x])
n = Matrix(1, 2, [3, Abs(x)])
assert abs(m) == n
def test_addition():
a = Matrix((
(1, 2),
(3, 1),
))
b = Matrix((
(1, 2),
(3, 0),
))
assert a + b == a.add(b) == Matrix([[2, 4], [6, 1]])
def test_fancy_index_matrix():
for M in (Matrix, SparseMatrix):
a = M(3, 3, range(9))
assert a == a[:, :]
assert a[1, :] == Matrix(1, 3, [3, 4, 5])
assert a[:, 1] == Matrix([1, 4, 7])
assert a[[0, 1], :] == Matrix([[0, 1, 2], [3, 4, 5]])
assert a[[0, 1], 2] == a[[0, 1], [2]]
assert a[2, [0, 1]] == a[[2], [0, 1]]
assert a[:, [0, 1]] == Matrix([[0, 1], [3, 4], [6, 7]])
assert a[0, 0] == 0
assert a[0:2, :] == Matrix([[0, 1, 2], [3, 4, 5]])
assert a[:, 0:2] == Matrix([[0, 1], [3, 4], [6, 7]])
assert a[::2, 1] == a[[0, 2], 1]
assert a[1, ::2] == a[1, [0, 2]]
a = M(3, 3, range(9))
assert a[[0, 2, 1, 2, 1], :] == Matrix([
[0, 1, 2],
[6, 7, 8],
[3, 4, 5],
[6, 7, 8],
[3, 4, 5]])
assert a[:, [0,2,1,2,1]] == Matrix([
[0, 2, 1, 2, 1],
[3, 5, 4, 5, 4],
[6, 8, 7, 8, 7]])
a = SparseMatrix.zeros(3)
a[1, 2] = 2
a[0, 1] = 3
a[2, 0] = 4
assert a.extract([1, 1], [2]) == Matrix([
[2],
[2]])
assert a.extract([1, 0], [2, 2, 2]) == Matrix([
[2, 2, 2],
[0, 0, 0]])
assert a.extract([1, 0, 1, 2], [2, 0, 1, 0]) == Matrix([
[2, 0, 0, 0],
[0, 0, 3, 0],
[2, 0, 0, 0],
[0, 4, 0, 4]])
def test_multiplication():
a = Matrix((
(1, 2),
(3, 1),
(0, 6),
))
b = Matrix((
(1, 2),
(3, 0),
))
c = a*b
assert c[0, 0] == 7
assert c[0, 1] == 2
assert c[1, 0] == 6
assert c[1, 1] == 6
assert c[2, 0] == 18
assert c[2, 1] == 0
try:
eval('c = a @ b')
except SyntaxError:
pass
else:
assert c[0, 0] == 7
assert c[0, 1] == 2
assert c[1, 0] == 6
assert c[1, 1] == 6
assert c[2, 0] == 18
assert c[2, 1] == 0
h = matrix_multiply_elementwise(a, c)
assert h == a.multiply_elementwise(c)
assert h[0, 0] == 7
assert h[0, 1] == 4
assert h[1, 0] == 18
assert h[1, 1] == 6
assert h[2, 0] == 0
assert h[2, 1] == 0
raises(ShapeError, lambda: matrix_multiply_elementwise(a, b))
c = b * Symbol("x")
assert isinstance(c, Matrix)
assert c[0, 0] == x
assert c[0, 1] == 2*x
assert c[1, 0] == 3*x
assert c[1, 1] == 0
c2 = x * b
assert c == c2
c = 5 * b
assert isinstance(c, Matrix)
assert c[0, 0] == 5
assert c[0, 1] == 2*5
assert c[1, 0] == 3*5
assert c[1, 1] == 0
try:
eval('c = 5 @ b')
except SyntaxError:
pass
else:
assert isinstance(c, Matrix)
assert c[0, 0] == 5
assert c[0, 1] == 2*5
assert c[1, 0] == 3*5
assert c[1, 1] == 0
def test_power():
raises(NonSquareMatrixError, lambda: Matrix((1, 2))**2)
R = Rational
A = Matrix([[2, 3], [4, 5]])
assert (A**-3)[:] == [R(-269)/8, R(153)/8, R(51)/2, R(-29)/2]
assert (A**5)[:] == [6140, 8097, 10796, 14237]
A = Matrix([[2, 1, 3], [4, 2, 4], [6, 12, 1]])
assert (A**3)[:] == [290, 262, 251, 448, 440, 368, 702, 954, 433]
assert A**0 == eye(3)
assert A**1 == A
assert (Matrix([[2]]) ** 100)[0, 0] == 2**100
assert eye(2)**10000000 == eye(2)
assert Matrix([[1, 2], [3, 4]])**Integer(2) == Matrix([[7, 10], [15, 22]])
A = Matrix([[33, 24], [48, 57]])
assert (A**(S(1)/2))[:] == [5, 2, 4, 7]
A = Matrix([[0, 4], [-1, 5]])
assert (A**(S(1)/2))**2 == A
assert Matrix([[1, 0], [1, 1]])**(S(1)/2) == Matrix([[1, 0], [S.Half, 1]])
assert Matrix([[1, 0], [1, 1]])**0.5 == Matrix([[1.0, 0], [0.5, 1.0]])
from sympy.abc import a, b, n
assert Matrix([[1, a], [0, 1]])**n == Matrix([[1, a*n], [0, 1]])
assert Matrix([[b, a], [0, b]])**n == Matrix([[b**n, a*b**(n-1)*n], [0, b**n]])
assert Matrix([[a, 1, 0], [0, a, 1], [0, 0, a]])**n == Matrix([
[a**n, a**(n-1)*n, a**(n-2)*(n-1)*n/2],
[0, a**n, a**(n-1)*n],
[0, 0, a**n]])
assert Matrix([[a, 1, 0], [0, a, 0], [0, 0, b]])**n == Matrix([
[a**n, a**(n-1)*n, 0],
[0, a**n, 0],
[0, 0, b**n]])
A = Matrix([[1, 0], [1, 7]])
assert A._matrix_pow_by_jordan_blocks(3) == A._eval_pow_by_recursion(3)
A = Matrix([[2]])
assert A**10 == Matrix([[2**10]]) == A._matrix_pow_by_jordan_blocks(10) == \
A._eval_pow_by_recursion(10)
# testing a matrix that cannot be jordan blocked issue 11766
m = Matrix([[3, 0, 0, 0, -3], [0, -3, -3, 0, 3], [0, 3, 0, 3, 0], [0, 0, 3, 0, 3], [3, 0, 0, 3, 0]])
raises(MatrixError, lambda: m._matrix_pow_by_jordan_blocks(10))
# test issue 11964
raises(ValueError, lambda: Matrix([[1, 1], [3, 3]])._matrix_pow_by_jordan_blocks(-10))
A = Matrix([[0, 1, 0], [0, 0, 1], [0, 0, 0]]) # Nilpotent jordan block size 3
assert A**10.0 == Matrix([[0, 0, 0], [0, 0, 0], [0, 0, 0]])
raises(ValueError, lambda: A**2.1)
raises(ValueError, lambda: A**(S(3)/2))
A = Matrix([[8, 1], [3, 2]])
assert A**10.0 == Matrix([[1760744107, 272388050], [817164150, 126415807]])
A = Matrix([[0, 0, 1], [0, 0, 1], [0, 0, 1]]) # Nilpotent jordan block size 1
assert A**10.2 == Matrix([[0, 0, 1], [0, 0, 1], [0, 0, 1]])
A = Matrix([[0, 1, 0], [0, 0, 1], [0, 0, 1]]) # Nilpotent jordan block size 2
assert A**10.0 == Matrix([[0, 0, 1], [0, 0, 1], [0, 0, 1]])
n = Symbol('n', integer=True)
assert isinstance(A**n, MatPow)
n = Symbol('n', integer=True, nonnegative=True)
raises(ValueError, lambda: A**n)
assert A**(n + 2) == Matrix([[0, 0, 1], [0, 0, 1], [0, 0, 1]])
raises(ValueError, lambda: A**(S(3)/2))
A = Matrix([[0, 0, 1], [3, 0, 1], [4, 3, 1]])
assert A**5.0 == Matrix([[168, 72, 89], [291, 144, 161], [572, 267, 329]])
assert A**5.0 == A**5
A = Matrix([[0, 1, 0],[-1, 0, 0],[0, 0, 0]])
n = Symbol("n")
An = A**n
assert An.subs(n, 2).doit() == A**2
raises(ValueError, lambda: An.subs(n, -2).doit())
assert An * An == A**(2*n)
def test_creation():
raises(ValueError, lambda: Matrix(5, 5, range(20)))
raises(ValueError, lambda: Matrix(5, -1, []))
raises(IndexError, lambda: Matrix((1, 2))[2])
with raises(IndexError):
Matrix((1, 2))[1:2] = 5
with raises(IndexError):
Matrix((1, 2))[3] = 5
assert Matrix() == Matrix([]) == Matrix([[]]) == Matrix(0, 0, [])
a = Matrix([[x, 0], [0, 0]])
m = a
assert m.cols == m.rows
assert m.cols == 2
assert m[:] == [x, 0, 0, 0]
b = Matrix(2, 2, [x, 0, 0, 0])
m = b
assert m.cols == m.rows
assert m.cols == 2
assert m[:] == [x, 0, 0, 0]
assert a == b
assert Matrix(b) == b
c = Matrix((
Matrix((
(1, 2, 3),
(4, 5, 6)
)),
(7, 8, 9)
))
assert c.cols == 3
assert c.rows == 3
assert c[:] == [1, 2, 3, 4, 5, 6, 7, 8, 9]
assert Matrix(eye(2)) == eye(2)
assert ImmutableMatrix(ImmutableMatrix(eye(2))) == ImmutableMatrix(eye(2))
assert ImmutableMatrix(c) == c.as_immutable()
assert Matrix(ImmutableMatrix(c)) == ImmutableMatrix(c).as_mutable()
assert c is not Matrix(c)
def test_tolist():
lst = [[S.One, S.Half, x*y, S.Zero], [x, y, z, x**2], [y, -S.One, z*x, 3]]
m = Matrix(lst)
assert m.tolist() == lst
def test_as_mutable():
assert zeros(0, 3).as_mutable() == zeros(0, 3)
assert zeros(0, 3).as_immutable() == ImmutableMatrix(zeros(0, 3))
assert zeros(3, 0).as_immutable() == ImmutableMatrix(zeros(3, 0))
def test_determinant():
for M in [Matrix(), Matrix([[1]])]:
assert (
M.det() ==
M._eval_det_bareiss() ==
M._eval_det_berkowitz() ==
M._eval_det_lu() ==
1)
M = Matrix(( (-3, 2),
( 8, -5) ))
assert M.det(method="bareiss") == -1
assert M.det(method="berkowitz") == -1
assert M.det(method="lu") == -1
M = Matrix(( (x, 1),
(y, 2*y) ))
assert M.det(method="bareiss") == 2*x*y - y
assert M.det(method="berkowitz") == 2*x*y - y
assert M.det(method="lu") == 2*x*y - y
M = Matrix(( (1, 1, 1),
(1, 2, 3),
(1, 3, 6) ))
assert M.det(method="bareiss") == 1
assert M.det(method="berkowitz") == 1
assert M.det(method="lu") == 1
M = Matrix(( ( 3, -2, 0, 5),
(-2, 1, -2, 2),
( 0, -2, 5, 0),
( 5, 0, 3, 4) ))
assert M.det(method="bareiss") == -289
assert M.det(method="berkowitz") == -289
assert M.det(method="lu") == -289
M = Matrix(( ( 1, 2, 3, 4),
( 5, 6, 7, 8),
( 9, 10, 11, 12),
(13, 14, 15, 16) ))
assert M.det(method="bareiss") == 0
assert M.det(method="berkowitz") == 0
assert M.det(method="lu") == 0
M = Matrix(( (3, 2, 0, 0, 0),
(0, 3, 2, 0, 0),
(0, 0, 3, 2, 0),
(0, 0, 0, 3, 2),
(2, 0, 0, 0, 3) ))
assert M.det(method="bareiss") == 275
assert M.det(method="berkowitz") == 275
assert M.det(method="lu") == 275
M = Matrix(( (1, 0, 1, 2, 12),
(2, 0, 1, 1, 4),
(2, 1, 1, -1, 3),
(3, 2, -1, 1, 8),
(1, 1, 1, 0, 6) ))
assert M.det(method="bareiss") == -55
assert M.det(method="berkowitz") == -55
assert M.det(method="lu") == -55
M = Matrix(( (-5, 2, 3, 4, 5),
( 1, -4, 3, 4, 5),
( 1, 2, -3, 4, 5),
( 1, 2, 3, -2, 5),
( 1, 2, 3, 4, -1) ))
assert M.det(method="bareiss") == 11664
assert M.det(method="berkowitz") == 11664
assert M.det(method="lu") == 11664
M = Matrix(( ( 2, 7, -1, 3, 2),
( 0, 0, 1, 0, 1),
(-2, 0, 7, 0, 2),
(-3, -2, 4, 5, 3),
( 1, 0, 0, 0, 1) ))
assert M.det(method="bareiss") == 123
assert M.det(method="berkowitz") == 123
assert M.det(method="lu") == 123
M = Matrix(( (x, y, z),
(1, 0, 0),
(y, z, x) ))
assert M.det(method="bareiss") == z**2 - x*y
assert M.det(method="berkowitz") == z**2 - x*y
assert M.det(method="lu") == z**2 - x*y
# issue 13835
a = symbols('a')
M = lambda n: Matrix([[i + a*j for i in range(n)]
for j in range(n)])
assert M(5).det() == 0
assert M(6).det() == 0
assert M(7).det() == 0
def test_slicing():
m0 = eye(4)
assert m0[:3, :3] == eye(3)
assert m0[2:4, 0:2] == zeros(2)
m1 = Matrix(3, 3, lambda i, j: i + j)
assert m1[0, :] == Matrix(1, 3, (0, 1, 2))
assert m1[1:3, 1] == Matrix(2, 1, (2, 3))
m2 = Matrix([[0, 1, 2, 3], [4, 5, 6, 7], [8, 9, 10, 11], [12, 13, 14, 15]])
assert m2[:, -1] == Matrix(4, 1, [3, 7, 11, 15])
assert m2[-2:, :] == Matrix([[8, 9, 10, 11], [12, 13, 14, 15]])
def test_submatrix_assignment():
m = zeros(4)
m[2:4, 2:4] = eye(2)
assert m == Matrix(((0, 0, 0, 0),
(0, 0, 0, 0),
(0, 0, 1, 0),
(0, 0, 0, 1)))
m[:2, :2] = eye(2)
assert m == eye(4)
m[:, 0] = Matrix(4, 1, (1, 2, 3, 4))
assert m == Matrix(((1, 0, 0, 0),
(2, 1, 0, 0),
(3, 0, 1, 0),
(4, 0, 0, 1)))
m[:, :] = zeros(4)
assert m == zeros(4)
m[:, :] = [(1, 2, 3, 4), (5, 6, 7, 8), (9, 10, 11, 12), (13, 14, 15, 16)]
assert m == Matrix(((1, 2, 3, 4),
(5, 6, 7, 8),
(9, 10, 11, 12),
(13, 14, 15, 16)))
m[:2, 0] = [0, 0]
assert m == Matrix(((0, 2, 3, 4),
(0, 6, 7, 8),
(9, 10, 11, 12),
(13, 14, 15, 16)))
def test_extract():
m = Matrix(4, 3, lambda i, j: i*3 + j)
assert m.extract([0, 1, 3], [0, 1]) == Matrix(3, 2, [0, 1, 3, 4, 9, 10])
assert m.extract([0, 3], [0, 0, 2]) == Matrix(2, 3, [0, 0, 2, 9, 9, 11])
assert m.extract(range(4), range(3)) == m
raises(IndexError, lambda: m.extract([4], [0]))
raises(IndexError, lambda: m.extract([0], [3]))
def test_reshape():
m0 = eye(3)
assert m0.reshape(1, 9) == Matrix(1, 9, (1, 0, 0, 0, 1, 0, 0, 0, 1))
m1 = Matrix(3, 4, lambda i, j: i + j)
assert m1.reshape(
4, 3) == Matrix(((0, 1, 2), (3, 1, 2), (3, 4, 2), (3, 4, 5)))
assert m1.reshape(2, 6) == Matrix(((0, 1, 2, 3, 1, 2), (3, 4, 2, 3, 4, 5)))
def test_applyfunc():
m0 = eye(3)
assert m0.applyfunc(lambda x: 2*x) == eye(3)*2
assert m0.applyfunc(lambda x: 0) == zeros(3)
def test_expand():
m0 = Matrix([[x*(x + y), 2], [((x + y)*y)*x, x*(y + x*(x + y))]])
# Test if expand() returns a matrix
m1 = m0.expand()
assert m1 == Matrix(
[[x*y + x**2, 2], [x*y**2 + y*x**2, x*y + y*x**2 + x**3]])
a = Symbol('a', real=True)
assert Matrix([exp(I*a)]).expand(complex=True) == \
Matrix([cos(a) + I*sin(a)])
assert Matrix([[0, 1, 2], [0, 0, -1], [0, 0, 0]]).exp() == Matrix([
[1, 1, Rational(3, 2)],
[0, 1, -1],
[0, 0, 1]]
)
def test_refine():
m0 = Matrix([[Abs(x)**2, sqrt(x**2)],
[sqrt(x**2)*Abs(y)**2, sqrt(y**2)*Abs(x)**2]])
m1 = m0.refine(Q.real(x) & Q.real(y))
assert m1 == Matrix([[x**2, Abs(x)], [y**2*Abs(x), x**2*Abs(y)]])
m1 = m0.refine(Q.positive(x) & Q.positive(y))
assert m1 == Matrix([[x**2, x], [x*y**2, x**2*y]])
m1 = m0.refine(Q.negative(x) & Q.negative(y))
assert m1 == Matrix([[x**2, -x], [-x*y**2, -x**2*y]])
def test_random():
M = randMatrix(3, 3)
M = randMatrix(3, 3, seed=3)
assert M == randMatrix(3, 3, seed=3)
M = randMatrix(3, 4, 0, 150)
M = randMatrix(3, seed=4, symmetric=True)
assert M == randMatrix(3, seed=4, symmetric=True)
S = M.copy()
S.simplify()
assert S == M # doesn't fail when elements are Numbers, not int
rng = random.Random(4)
assert M == randMatrix(3, symmetric=True, prng=rng)
# Ensure symmetry
for size in (10, 11): # Test odd and even
for percent in (100, 70, 30):
M = randMatrix(size, symmetric=True, percent=percent, prng=rng)
assert M == M.T
M = randMatrix(10, min=1, percent=70)
zero_count = 0
for i in range(M.shape[0]):
for j in range(M.shape[1]):
if M[i, j] == 0:
zero_count += 1
assert zero_count == 30
def test_LUdecomp():
testmat = Matrix([[0, 2, 5, 3],
[3, 3, 7, 4],
[8, 4, 0, 2],
[-2, 6, 3, 4]])
L, U, p = testmat.LUdecomposition()
assert L.is_lower
assert U.is_upper
assert (L*U).permute_rows(p, 'backward') - testmat == zeros(4)
testmat = Matrix([[6, -2, 7, 4],
[0, 3, 6, 7],
[1, -2, 7, 4],
[-9, 2, 6, 3]])
L, U, p = testmat.LUdecomposition()
assert L.is_lower
assert U.is_upper
assert (L*U).permute_rows(p, 'backward') - testmat == zeros(4)
# non-square
testmat = Matrix([[1, 2, 3],
[4, 5, 6],
[7, 8, 9],
[10, 11, 12]])
L, U, p = testmat.LUdecomposition(rankcheck=False)
assert L.is_lower
assert U.is_upper
assert (L*U).permute_rows(p, 'backward') - testmat == zeros(4, 3)
# square and singular
testmat = Matrix([[1, 2, 3],
[2, 4, 6],
[4, 5, 6]])
L, U, p = testmat.LUdecomposition(rankcheck=False)
assert L.is_lower
assert U.is_upper
assert (L*U).permute_rows(p, 'backward') - testmat == zeros(3)
M = Matrix(((1, x, 1), (2, y, 0), (y, 0, z)))
L, U, p = M.LUdecomposition()
assert L.is_lower
assert U.is_upper
assert (L*U).permute_rows(p, 'backward') - M == zeros(3)
mL = Matrix((
(1, 0, 0),
(2, 3, 0),
))
assert mL.is_lower is True
assert mL.is_upper is False
mU = Matrix((
(1, 2, 3),
(0, 4, 5),
))
assert mU.is_lower is False
assert mU.is_upper is True
# test FF LUdecomp
M = Matrix([[1, 3, 3],
[3, 2, 6],
[3, 2, 2]])
P, L, Dee, U = M.LUdecompositionFF()
assert P*M == L*Dee.inv()*U
M = Matrix([[1, 2, 3, 4],
[3, -1, 2, 3],
[3, 1, 3, -2],
[6, -1, 0, 2]])
P, L, Dee, U = M.LUdecompositionFF()
assert P*M == L*Dee.inv()*U
M = Matrix([[0, 0, 1],
[2, 3, 0],
[3, 1, 4]])
P, L, Dee, U = M.LUdecompositionFF()
assert P*M == L*Dee.inv()*U
# issue 15794
M = Matrix(
[[1, 2, 3],
[4, 5, 6],
[7, 8, 9]]
)
raises(ValueError, lambda : M.LUdecomposition_Simple(rankcheck=True))
def test_LUsolve():
A = Matrix([[2, 3, 5],
[3, 6, 2],
[8, 3, 6]])
x = Matrix(3, 1, [3, 7, 5])
b = A*x
soln = A.LUsolve(b)
assert soln == x
A = Matrix([[0, -1, 2],
[5, 10, 7],
[8, 3, 4]])
x = Matrix(3, 1, [-1, 2, 5])
b = A*x
soln = A.LUsolve(b)
assert soln == x
A = Matrix([[2, 1], [1, 0], [1, 0]]) # issue 14548
b = Matrix([3, 1, 1])
assert A.LUsolve(b) == Matrix([1, 1])
b = Matrix([3, 1, 2]) # inconsistent
raises(ValueError, lambda: A.LUsolve(b))
A = Matrix([[0, -1, 2],
[5, 10, 7],
[8, 3, 4],
[2, 3, 5],
[3, 6, 2],
[8, 3, 6]])
x = Matrix([2, 1, -4])
b = A*x
soln = A.LUsolve(b)
assert soln == x
A = Matrix([[0, -1, 2], [5, 10, 7]]) # underdetermined
x = Matrix([-1, 2, 0])
b = A*x
raises(NotImplementedError, lambda: A.LUsolve(b))
def test_QRsolve():
A = Matrix([[2, 3, 5],
[3, 6, 2],
[8, 3, 6]])
x = Matrix(3, 1, [3, 7, 5])
b = A*x
soln = A.QRsolve(b)
assert soln == x
x = Matrix([[1, 2], [3, 4], [5, 6]])
b = A*x
soln = A.QRsolve(b)
assert soln == x
A = Matrix([[0, -1, 2],
[5, 10, 7],
[8, 3, 4]])
x = Matrix(3, 1, [-1, 2, 5])
b = A*x
soln = A.QRsolve(b)
assert soln == x
x = Matrix([[7, 8], [9, 10], [11, 12]])
b = A*x
soln = A.QRsolve(b)
assert soln == x
def test_inverse():
A = eye(4)
assert A.inv() == eye(4)
assert A.inv(method="LU") == eye(4)
assert A.inv(method="ADJ") == eye(4)
A = Matrix([[2, 3, 5],
[3, 6, 2],
[8, 3, 6]])
Ainv = A.inv()
assert A*Ainv == eye(3)
assert A.inv(method="LU") == Ainv
assert A.inv(method="ADJ") == Ainv
# test that immutability is not a problem
cls = ImmutableMatrix
m = cls([[48, 49, 31],
[ 9, 71, 94],
[59, 28, 65]])
assert all(type(m.inv(s)) is cls for s in 'GE ADJ LU'.split())
cls = ImmutableSparseMatrix
m = cls([[48, 49, 31],
[ 9, 71, 94],
[59, 28, 65]])
assert all(type(m.inv(s)) is cls for s in 'CH LDL'.split())
def test_matrix_inverse_mod():
A = Matrix(2, 1, [1, 0])
raises(NonSquareMatrixError, lambda: A.inv_mod(2))
A = Matrix(2, 2, [1, 0, 0, 0])
raises(ValueError, lambda: A.inv_mod(2))
A = Matrix(2, 2, [1, 2, 3, 4])
Ai = Matrix(2, 2, [1, 1, 0, 1])
assert A.inv_mod(3) == Ai
A = Matrix(2, 2, [1, 0, 0, 1])
assert A.inv_mod(2) == A
A = Matrix(3, 3, [1, 2, 3, 4, 5, 6, 7, 8, 9])
raises(ValueError, lambda: A.inv_mod(5))
A = Matrix(3, 3, [5, 1, 3, 2, 6, 0, 2, 1, 1])
Ai = Matrix(3, 3, [6, 8, 0, 1, 5, 6, 5, 6, 4])
assert A.inv_mod(9) == Ai
A = Matrix(3, 3, [1, 6, -3, 4, 1, -5, 3, -5, 5])
Ai = Matrix(3, 3, [4, 3, 3, 1, 2, 5, 1, 5, 1])
assert A.inv_mod(6) == Ai
A = Matrix(3, 3, [1, 6, 1, 4, 1, 5, 3, 2, 5])
Ai = Matrix(3, 3, [6, 0, 3, 6, 6, 4, 1, 6, 1])
assert A.inv_mod(7) == Ai
def test_util():
R = Rational
v1 = Matrix(1, 3, [1, 2, 3])
v2 = Matrix(1, 3, [3, 4, 5])
assert v1.norm() == sqrt(14)
assert v1.project(v2) == Matrix(1, 3, [R(39)/25, R(52)/25, R(13)/5])
assert Matrix.zeros(1, 2) == Matrix(1, 2, [0, 0])
assert ones(1, 2) == Matrix(1, 2, [1, 1])
assert v1.copy() == v1
# cofactor
assert eye(3) == eye(3).cofactor_matrix()
test = Matrix([[1, 3, 2], [2, 6, 3], [2, 3, 6]])
assert test.cofactor_matrix() == \
Matrix([[27, -6, -6], [-12, 2, 3], [-3, 1, 0]])
test = Matrix([[1, 2, 3], [4, 5, 6], [7, 8, 9]])
assert test.cofactor_matrix() == \
Matrix([[-3, 6, -3], [6, -12, 6], [-3, 6, -3]])
def test_jacobian_hessian():
L = Matrix(1, 2, [x**2*y, 2*y**2 + x*y])
syms = [x, y]
assert L.jacobian(syms) == Matrix([[2*x*y, x**2], [y, 4*y + x]])
L = Matrix(1, 2, [x, x**2*y**3])
assert L.jacobian(syms) == Matrix([[1, 0], [2*x*y**3, x**2*3*y**2]])
f = x**2*y
syms = [x, y]
assert hessian(f, syms) == Matrix([[2*y, 2*x], [2*x, 0]])
f = x**2*y**3
assert hessian(f, syms) == \
Matrix([[2*y**3, 6*x*y**2], [6*x*y**2, 6*x**2*y]])
f = z + x*y**2
g = x**2 + 2*y**3
ans = Matrix([[0, 2*y],
[2*y, 2*x]])
assert ans == hessian(f, Matrix([x, y]))
assert ans == hessian(f, Matrix([x, y]).T)
assert hessian(f, (y, x), [g]) == Matrix([
[ 0, 6*y**2, 2*x],
[6*y**2, 2*x, 2*y],
[ 2*x, 2*y, 0]])
def test_QR():
A = Matrix([[1, 2], [2, 3]])
Q, S = A.QRdecomposition()
R = Rational
assert Q == Matrix([
[ 5**R(-1, 2), (R(2)/5)*(R(1)/5)**R(-1, 2)],
[2*5**R(-1, 2), (-R(1)/5)*(R(1)/5)**R(-1, 2)]])
assert S == Matrix([[5**R(1, 2), 8*5**R(-1, 2)], [0, (R(1)/5)**R(1, 2)]])
assert Q*S == A
assert Q.T * Q == eye(2)
A = Matrix([[1, 1, 1], [1, 1, 3], [2, 3, 4]])
Q, R = A.QRdecomposition()
assert Q.T * Q == eye(Q.cols)
assert R.is_upper
assert A == Q*R
def test_QR_non_square():
# Narrow (cols < rows) matrices
A = Matrix([[9, 0, 26], [12, 0, -7], [0, 4, 4], [0, -3, -3]])
Q, R = A.QRdecomposition()
assert Q.T * Q == eye(Q.cols)
assert R.is_upper
assert A == Q*R
A = Matrix([[1, -1, 4], [1, 4, -2], [1, 4, 2], [1, -1, 0]])
Q, R = A.QRdecomposition()
assert Q.T * Q == eye(Q.cols)
assert R.is_upper
assert A == Q*R
A = Matrix(2, 1, [1, 2])
Q, R = A.QRdecomposition()
assert Q.T * Q == eye(Q.cols)
assert R.is_upper
assert A == Q*R
# Wide (cols > rows) matrices
A = Matrix([[1, 2, 3], [4, 5, 6]])
Q, R = A.QRdecomposition()
assert Q.T * Q == eye(Q.cols)
assert R.is_upper
assert A == Q*R
A = Matrix([[1, 2, 3, 4], [1, 4, 9, 16], [1, 8, 27, 64]])
Q, R = A.QRdecomposition()
assert Q.T * Q == eye(Q.cols)
assert R.is_upper
assert A == Q*R
A = Matrix(1, 2, [1, 2])
Q, R = A.QRdecomposition()
assert Q.T * Q == eye(Q.cols)
assert R.is_upper
assert A == Q*R
def test_QR_trivial():
# Rank deficient matrices
A = Matrix([[1, 2, 3], [4, 5, 6], [7, 8, 9]])
Q, R = A.QRdecomposition()
assert Q.T * Q == eye(Q.cols)
assert R.is_upper
assert A == Q*R
A = Matrix([[1, 1, 1], [2, 2, 2], [3, 3, 3], [4, 4, 4]])
Q, R = A.QRdecomposition()
assert Q.T * Q == eye(Q.cols)
assert R.is_upper
assert A == Q*R
A = Matrix([[1, 1, 1], [2, 2, 2], [3, 3, 3], [4, 4, 4]]).T
Q, R = A.QRdecomposition()
assert Q.T * Q == eye(Q.cols)
assert R.is_upper
assert A == Q*R
# Zero rank matrices
A = Matrix([[0, 0, 0]])
Q, R = A.QRdecomposition()
assert Q.T * Q == eye(Q.cols)
assert R.is_upper
assert A == Q*R
A = Matrix([[0, 0, 0]]).T
Q, R = A.QRdecomposition()
assert Q.T * Q == eye(Q.cols)
assert R.is_upper
assert A == Q*R
A = Matrix([[0, 0, 0], [0, 0, 0]])
Q, R = A.QRdecomposition()
assert Q.T * Q == eye(Q.cols)
assert R.is_upper
assert A == Q*R
A = Matrix([[0, 0, 0], [0, 0, 0]]).T
Q, R = A.QRdecomposition()
assert Q.T * Q == eye(Q.cols)
assert R.is_upper
assert A == Q*R
# Rank deficient matrices with zero norm from beginning columns
A = Matrix([[0, 0, 0], [1, 2, 3]]).T
Q, R = A.QRdecomposition()
assert Q.T * Q == eye(Q.cols)
assert R.is_upper
assert A == Q*R
A = Matrix([[0, 0, 0, 0], [1, 2, 3, 4], [0, 0, 0, 0]]).T
Q, R = A.QRdecomposition()
assert Q.T * Q == eye(Q.cols)
assert R.is_upper
assert A == Q*R
A = Matrix([[0, 0, 0, 0], [1, 2, 3, 4], [0, 0, 0, 0], [2, 4, 6, 8]]).T
Q, R = A.QRdecomposition()
assert Q.T * Q == eye(Q.cols)
assert R.is_upper
assert A == Q*R
A = Matrix([[0, 0, 0], [0, 0, 0], [0, 0, 0], [1, 2, 3]]).T
Q, R = A.QRdecomposition()
assert Q.T * Q == eye(Q.cols)
assert R.is_upper
assert A == Q*R
def test_nullspace():
# first test reduced row-ech form
R = Rational
M = Matrix([[5, 7, 2, 1],
[1, 6, 2, -1]])
out, tmp = M.rref()
assert out == Matrix([[1, 0, -R(2)/23, R(13)/23],
[0, 1, R(8)/23, R(-6)/23]])
M = Matrix([[-5, -1, 4, -3, -1],
[ 1, -1, -1, 1, 0],
[-1, 0, 0, 0, 0],
[ 4, 1, -4, 3, 1],
[-2, 0, 2, -2, -1]])
assert M*M.nullspace()[0] == Matrix(5, 1, [0]*5)
M = Matrix([[ 1, 3, 0, 2, 6, 3, 1],
[-2, -6, 0, -2, -8, 3, 1],
[ 3, 9, 0, 0, 6, 6, 2],
[-1, -3, 0, 1, 0, 9, 3]])
out, tmp = M.rref()
assert out == Matrix([[1, 3, 0, 0, 2, 0, 0],
[0, 0, 0, 1, 2, 0, 0],
[0, 0, 0, 0, 0, 1, R(1)/3],
[0, 0, 0, 0, 0, 0, 0]])
# now check the vectors
basis = M.nullspace()
assert basis[0] == Matrix([-3, 1, 0, 0, 0, 0, 0])
assert basis[1] == Matrix([0, 0, 1, 0, 0, 0, 0])
assert basis[2] == Matrix([-2, 0, 0, -2, 1, 0, 0])
assert basis[3] == Matrix([0, 0, 0, 0, 0, R(-1)/3, 1])
# issue 4797; just see that we can do it when rows > cols
M = Matrix([[1, 2], [2, 4], [3, 6]])
assert M.nullspace()
def test_columnspace():
M = Matrix([[ 1, 2, 0, 2, 5],
[-2, -5, 1, -1, -8],
[ 0, -3, 3, 4, 1],
[ 3, 6, 0, -7, 2]])
# now check the vectors
basis = M.columnspace()
assert basis[0] == Matrix([1, -2, 0, 3])
assert basis[1] == Matrix([2, -5, -3, 6])
assert basis[2] == Matrix([2, -1, 4, -7])
#check by columnspace definition
a, b, c, d, e = symbols('a b c d e')
X = Matrix([a, b, c, d, e])
for i in range(len(basis)):
eq=M*X-basis[i]
assert len(solve(eq, X)) != 0
#check if rank-nullity theorem holds
assert M.rank() == len(basis)
assert len(M.nullspace()) + len(M.columnspace()) == M.cols
def test_wronskian():
assert wronskian([cos(x), sin(x)], x) == cos(x)**2 + sin(x)**2
assert wronskian([exp(x), exp(2*x)], x) == exp(3*x)
assert wronskian([exp(x), x], x) == exp(x) - x*exp(x)
assert wronskian([1, x, x**2], x) == 2
w1 = -6*exp(x)*sin(x)*x + 6*cos(x)*exp(x)*x**2 - 6*exp(x)*cos(x)*x - \
exp(x)*cos(x)*x**3 + exp(x)*sin(x)*x**3
assert wronskian([exp(x), cos(x), x**3], x).expand() == w1
assert wronskian([exp(x), cos(x), x**3], x, method='berkowitz').expand() \
== w1
w2 = -x**3*cos(x)**2 - x**3*sin(x)**2 - 6*x*cos(x)**2 - 6*x*sin(x)**2
assert wronskian([sin(x), cos(x), x**3], x).expand() == w2
assert wronskian([sin(x), cos(x), x**3], x, method='berkowitz').expand() \
== w2
assert wronskian([], x) == 1
def test_eigen():
R = Rational
assert eye(3).charpoly(x) == Poly((x - 1)**3, x)
assert eye(3).charpoly(y) == Poly((y - 1)**3, y)
M = Matrix([[1, 0, 0],
[0, 1, 0],
[0, 0, 1]])
assert M.eigenvals(multiple=False) == {S.One: 3}
assert M.eigenvals(multiple=True) == [1, 1, 1]
assert M.eigenvects() == (
[(1, 3, [Matrix([1, 0, 0]),
Matrix([0, 1, 0]),
Matrix([0, 0, 1])])])
assert M.left_eigenvects() == (
[(1, 3, [Matrix([[1, 0, 0]]),
Matrix([[0, 1, 0]]),
Matrix([[0, 0, 1]])])])
M = Matrix([[0, 1, 1],
[1, 0, 0],
[1, 1, 1]])
assert M.eigenvals() == {2*S.One: 1, -S.One: 1, S.Zero: 1}
assert M.eigenvects() == (
[
(-1, 1, [Matrix([-1, 1, 0])]),
( 0, 1, [Matrix([0, -1, 1])]),
( 2, 1, [Matrix([R(2, 3), R(1, 3), 1])])
])
assert M.left_eigenvects() == (
[
(-1, 1, [Matrix([[-2, 1, 1]])]),
(0, 1, [Matrix([[-1, -1, 1]])]),
(2, 1, [Matrix([[1, 1, 1]])])
])
a = Symbol('a')
M = Matrix([[a, 0],
[0, 1]])
assert M.eigenvals() == {a: 1, S.One: 1}
M = Matrix([[1, -1],
[1, 3]])
assert M.eigenvects() == ([(2, 2, [Matrix(2, 1, [-1, 1])])])
assert M.left_eigenvects() == ([(2, 2, [Matrix([[1, 1]])])])
M = Matrix([[1, 2, 3], [4, 5, 6], [7, 8, 9]])
a = R(15, 2)
b = 3*33**R(1, 2)
c = R(13, 2)
d = (R(33, 8) + 3*b/8)
e = (R(33, 8) - 3*b/8)
def NS(e, n):
return str(N(e, n))
r = [
(a - b/2, 1, [Matrix([(12 + 24/(c - b/2))/((c - b/2)*e) + 3/(c - b/2),
(6 + 12/(c - b/2))/e, 1])]),
( 0, 1, [Matrix([1, -2, 1])]),
(a + b/2, 1, [Matrix([(12 + 24/(c + b/2))/((c + b/2)*d) + 3/(c + b/2),
(6 + 12/(c + b/2))/d, 1])]),
]
r1 = [(NS(r[i][0], 2), NS(r[i][1], 2),
[NS(j, 2) for j in r[i][2][0]]) for i in range(len(r))]
r = M.eigenvects()
r2 = [(NS(r[i][0], 2), NS(r[i][1], 2),
[NS(j, 2) for j in r[i][2][0]]) for i in range(len(r))]
assert sorted(r1) == sorted(r2)
eps = Symbol('eps', real=True)
M = Matrix([[abs(eps), I*eps ],
[-I*eps, abs(eps) ]])
assert M.eigenvects() == (
[
( 0, 1, [Matrix([[-I*eps/abs(eps)], [1]])]),
( 2*abs(eps), 1, [ Matrix([[I*eps/abs(eps)], [1]]) ] ),
])
assert M.left_eigenvects() == (
[
(0, 1, [Matrix([[I*eps/Abs(eps), 1]])]),
(2*Abs(eps), 1, [Matrix([[-I*eps/Abs(eps), 1]])])
])
M = Matrix(3, 3, [1, 2, 0, 0, 3, 0, 2, -4, 2])
M._eigenvects = M.eigenvects(simplify=False)
assert max(i.q for i in M._eigenvects[0][2][0]) > 1
M._eigenvects = M.eigenvects(simplify=True)
assert max(i.q for i in M._eigenvects[0][2][0]) == 1
M = Matrix([[S(1)/4, 1], [1, 1]])
assert M.eigenvects(simplify=True) == [
(S(5)/8 + sqrt(73)/8, 1, [Matrix([[-S(3)/8 + sqrt(73)/8], [1]])]),
(-sqrt(73)/8 + S(5)/8, 1, [Matrix([[-sqrt(73)/8 - S(3)/8], [1]])])]
assert M.eigenvects(simplify=False) ==[(S(5)/8 + sqrt(73)/8, 1, [Matrix([
[-1/(-sqrt(73)/8 - S(3)/8)],
[ 1]])]), (-sqrt(73)/8 + S(5)/8, 1, [Matrix([
[-1/(-S(3)/8 + sqrt(73)/8)],
[ 1]])])]
m = Matrix([[1, .6, .6], [.6, .9, .9], [.9, .6, .6]])
evals = {-sqrt(385)/20 + S(5)/4: 1, sqrt(385)/20 + S(5)/4: 1, S.Zero: 1}
assert m.eigenvals() == evals
nevals = list(sorted(m.eigenvals(rational=False).keys()))
sevals = list(sorted(evals.keys()))
assert all(abs(nevals[i] - sevals[i]) < 1e-9 for i in range(len(nevals)))
# issue 10719
assert Matrix([]).eigenvals() == {}
assert Matrix([]).eigenvects() == []
# issue 15119
raises(NonSquareMatrixError, lambda : Matrix([[1, 2], [0, 4], [0, 0]]).eigenvals())
raises(NonSquareMatrixError, lambda : Matrix([[1, 0], [3, 4], [5, 6]]).eigenvals())
raises(NonSquareMatrixError, lambda : Matrix([[1, 2, 3], [0, 5, 6]]).eigenvals())
raises(NonSquareMatrixError, lambda : Matrix([[1, 0, 0], [4, 5, 0]]).eigenvals())
raises(NonSquareMatrixError, lambda : Matrix([[1, 2, 3], [0, 5, 6]]).eigenvals(error_when_incomplete = False))
raises(NonSquareMatrixError, lambda : Matrix([[1, 0, 0], [4, 5, 0]]).eigenvals(error_when_incomplete = False))
# issue 15125
from sympy.core.function import count_ops
q = Symbol("q", positive = True)
m = Matrix([[-2, exp(-q), 1], [exp(q), -2, 1], [1, 1, -2]])
assert count_ops(m.eigenvals(simplify=False)) > count_ops(m.eigenvals(simplify=True))
assert count_ops(m.eigenvals(simplify=lambda x: x)) > count_ops(m.eigenvals(simplify=True))
assert isinstance(m.eigenvals(simplify=True, multiple=False), dict)
assert isinstance(m.eigenvals(simplify=True, multiple=True), list)
assert isinstance(m.eigenvals(simplify=lambda x: x, multiple=False), dict)
assert isinstance(m.eigenvals(simplify=lambda x: x, multiple=True), list)
def test_subs():
assert Matrix([[1, x], [x, 4]]).subs(x, 5) == Matrix([[1, 5], [5, 4]])
assert Matrix([[x, 2], [x + y, 4]]).subs([[x, -1], [y, -2]]) == \
Matrix([[-1, 2], [-3, 4]])
assert Matrix([[x, 2], [x + y, 4]]).subs([(x, -1), (y, -2)]) == \
Matrix([[-1, 2], [-3, 4]])
assert Matrix([[x, 2], [x + y, 4]]).subs({x: -1, y: -2}) == \
Matrix([[-1, 2], [-3, 4]])
assert Matrix([x*y]).subs({x: y - 1, y: x - 1}, simultaneous=True) == \
Matrix([(x - 1)*(y - 1)])
for cls in classes:
assert Matrix([[2, 0], [0, 2]]) == cls.eye(2).subs(1, 2)
def test_xreplace():
assert Matrix([[1, x], [x, 4]]).xreplace({x: 5}) == \
Matrix([[1, 5], [5, 4]])
assert Matrix([[x, 2], [x + y, 4]]).xreplace({x: -1, y: -2}) == \
Matrix([[-1, 2], [-3, 4]])
for cls in classes:
assert Matrix([[2, 0], [0, 2]]) == cls.eye(2).xreplace({1: 2})
def test_simplify():
n = Symbol('n')
f = Function('f')
M = Matrix([[ 1/x + 1/y, (x + x*y) / x ],
[ (f(x) + y*f(x))/f(x), 2 * (1/n - cos(n * pi)/n) / pi ]])
M.simplify()
assert M == Matrix([[ (x + y)/(x * y), 1 + y ],
[ 1 + y, 2*((1 - 1*cos(pi*n))/(pi*n)) ]])
eq = (1 + x)**2
M = Matrix([[eq]])
M.simplify()
assert M == Matrix([[eq]])
M.simplify(ratio=oo) == M
assert M == Matrix([[eq.simplify(ratio=oo)]])
def test_transpose():
M = Matrix([[1, 2, 3, 4, 5, 6, 7, 8, 9, 0],
[1, 2, 3, 4, 5, 6, 7, 8, 9, 0]])
assert M.T == Matrix( [ [1, 1],
[2, 2],
[3, 3],
[4, 4],
[5, 5],
[6, 6],
[7, 7],
[8, 8],
[9, 9],
[0, 0] ])
assert M.T.T == M
assert M.T == M.transpose()
def test_conjugate():
M = Matrix([[0, I, 5],
[1, 2, 0]])
assert M.T == Matrix([[0, 1],
[I, 2],
[5, 0]])
assert M.C == Matrix([[0, -I, 5],
[1, 2, 0]])
assert M.C == M.conjugate()
assert M.H == M.T.C
assert M.H == Matrix([[ 0, 1],
[-I, 2],
[ 5, 0]])
def test_conj_dirac():
raises(AttributeError, lambda: eye(3).D)
M = Matrix([[1, I, I, I],
[0, 1, I, I],
[0, 0, 1, I],
[0, 0, 0, 1]])
assert M.D == Matrix([[ 1, 0, 0, 0],
[-I, 1, 0, 0],
[-I, -I, -1, 0],
[-I, -I, I, -1]])
def test_trace():
M = Matrix([[1, 0, 0],
[0, 5, 0],
[0, 0, 8]])
assert M.trace() == 14
def test_shape():
M = Matrix([[x, 0, 0],
[0, y, 0]])
assert M.shape == (2, 3)
def test_col_row_op():
M = Matrix([[x, 0, 0],
[0, y, 0]])
M.row_op(1, lambda r, j: r + j + 1)
assert M == Matrix([[x, 0, 0],
[1, y + 2, 3]])
M.col_op(0, lambda c, j: c + y**j)
assert M == Matrix([[x + 1, 0, 0],
[1 + y, y + 2, 3]])
# neither row nor slice give copies that allow the original matrix to
# be changed
assert M.row(0) == Matrix([[x + 1, 0, 0]])
r1 = M.row(0)
r1[0] = 42
assert M[0, 0] == x + 1
r1 = M[0, :-1] # also testing negative slice
r1[0] = 42
assert M[0, 0] == x + 1
c1 = M.col(0)
assert c1 == Matrix([x + 1, 1 + y])
c1[0] = 0
assert M[0, 0] == x + 1
c1 = M[:, 0]
c1[0] = 42
assert M[0, 0] == x + 1
def test_zip_row_op():
for cls in classes[:2]: # XXX: immutable matrices don't support row ops
M = cls.eye(3)
M.zip_row_op(1, 0, lambda v, u: v + 2*u)
assert M == cls([[1, 0, 0],
[2, 1, 0],
[0, 0, 1]])
M = cls.eye(3)*2
M[0, 1] = -1
M.zip_row_op(1, 0, lambda v, u: v + 2*u); M
assert M == cls([[2, -1, 0],
[4, 0, 0],
[0, 0, 2]])
def test_issue_3950():
m = Matrix([1, 2, 3])
a = Matrix([1, 2, 3])
b = Matrix([2, 2, 3])
assert not (m in [])
assert not (m in [1])
assert m != 1
assert m == a
assert m != b
def test_issue_3981():
class Index1(object):
def __index__(self):
return 1
class Index2(object):
def __index__(self):
return 2
index1 = Index1()
index2 = Index2()
m = Matrix([1, 2, 3])
assert m[index2] == 3
m[index2] = 5
assert m[2] == 5
m = Matrix([[1, 2, 3], [4, 5, 6]])
assert m[index1, index2] == 6
assert m[1, index2] == 6
assert m[index1, 2] == 6
m[index1, index2] = 4
assert m[1, 2] == 4
m[1, index2] = 6
assert m[1, 2] == 6
m[index1, 2] = 8
assert m[1, 2] == 8
def test_evalf():
a = Matrix([sqrt(5), 6])
assert all(a.evalf()[i] == a[i].evalf() for i in range(2))
assert all(a.evalf(2)[i] == a[i].evalf(2) for i in range(2))
assert all(a.n(2)[i] == a[i].n(2) for i in range(2))
def test_is_symbolic():
a = Matrix([[x, x], [x, x]])
assert a.is_symbolic() is True
a = Matrix([[1, 2, 3, 4], [5, 6, 7, 8]])
assert a.is_symbolic() is False
a = Matrix([[1, 2, 3, 4], [5, 6, x, 8]])
assert a.is_symbolic() is True
a = Matrix([[1, x, 3]])
assert a.is_symbolic() is True
a = Matrix([[1, 2, 3]])
assert a.is_symbolic() is False
a = Matrix([[1], [x], [3]])
assert a.is_symbolic() is True
a = Matrix([[1], [2], [3]])
assert a.is_symbolic() is False
def test_is_upper():
a = Matrix([[1, 2, 3]])
assert a.is_upper is True
a = Matrix([[1], [2], [3]])
assert a.is_upper is False
a = zeros(4, 2)
assert a.is_upper is True
def test_is_lower():
a = Matrix([[1, 2, 3]])
assert a.is_lower is False
a = Matrix([[1], [2], [3]])
assert a.is_lower is True
def test_is_nilpotent():
a = Matrix(4, 4, [0, 2, 1, 6, 0, 0, 1, 2, 0, 0, 0, 3, 0, 0, 0, 0])
assert a.is_nilpotent()
a = Matrix([[1, 0], [0, 1]])
assert not a.is_nilpotent()
a = Matrix([])
assert a.is_nilpotent()
def test_zeros_ones_fill():
n, m = 3, 5
a = zeros(n, m)
a.fill( 5 )
b = 5 * ones(n, m)
assert a == b
assert a.rows == b.rows == 3
assert a.cols == b.cols == 5
assert a.shape == b.shape == (3, 5)
assert zeros(2) == zeros(2, 2)
assert ones(2) == ones(2, 2)
assert zeros(2, 3) == Matrix(2, 3, [0]*6)
assert ones(2, 3) == Matrix(2, 3, [1]*6)
def test_empty_zeros():
a = zeros(0)
assert a == Matrix()
a = zeros(0, 2)
assert a.rows == 0
assert a.cols == 2
a = zeros(2, 0)
assert a.rows == 2
assert a.cols == 0
def test_issue_3749():
a = Matrix([[x**2, x*y], [x*sin(y), x*cos(y)]])
assert a.diff(x) == Matrix([[2*x, y], [sin(y), cos(y)]])
assert Matrix([
[x, -x, x**2],
[exp(x), 1/x - exp(-x), x + 1/x]]).limit(x, oo) == \
Matrix([[oo, -oo, oo], [oo, 0, oo]])
assert Matrix([
[(exp(x) - 1)/x, 2*x + y*x, x**x ],
[1/x, abs(x), abs(sin(x + 1))]]).limit(x, 0) == \
Matrix([[1, 0, 1], [oo, 0, sin(1)]])
assert a.integrate(x) == Matrix([
[Rational(1, 3)*x**3, y*x**2/2],
[x**2*sin(y)/2, x**2*cos(y)/2]])
def test_inv_iszerofunc():
A = eye(4)
A.col_swap(0, 1)
for method in "GE", "LU":
assert A.inv(method=method, iszerofunc=lambda x: x == 0) == \
A.inv(method="ADJ")
def test_jacobian_metrics():
rho, phi = symbols("rho,phi")
X = Matrix([rho*cos(phi), rho*sin(phi)])
Y = Matrix([rho, phi])
J = X.jacobian(Y)
assert J == X.jacobian(Y.T)
assert J == (X.T).jacobian(Y)
assert J == (X.T).jacobian(Y.T)
g = J.T*eye(J.shape[0])*J
g = g.applyfunc(trigsimp)
assert g == Matrix([[1, 0], [0, rho**2]])
def test_jacobian2():
rho, phi = symbols("rho,phi")
X = Matrix([rho*cos(phi), rho*sin(phi), rho**2])
Y = Matrix([rho, phi])
J = Matrix([
[cos(phi), -rho*sin(phi)],
[sin(phi), rho*cos(phi)],
[ 2*rho, 0],
])
assert X.jacobian(Y) == J
def test_issue_4564():
X = Matrix([exp(x + y + z), exp(x + y + z), exp(x + y + z)])
Y = Matrix([x, y, z])
for i in range(1, 3):
for j in range(1, 3):
X_slice = X[:i, :]
Y_slice = Y[:j, :]
J = X_slice.jacobian(Y_slice)
assert J.rows == i
assert J.cols == j
for k in range(j):
assert J[:, k] == X_slice
def test_nonvectorJacobian():
X = Matrix([[exp(x + y + z), exp(x + y + z)],
[exp(x + y + z), exp(x + y + z)]])
raises(TypeError, lambda: X.jacobian(Matrix([x, y, z])))
X = X[0, :]
Y = Matrix([[x, y], [x, z]])
raises(TypeError, lambda: X.jacobian(Y))
raises(TypeError, lambda: X.jacobian(Matrix([ [x, y], [x, z] ])))
def test_vec():
m = Matrix([[1, 3], [2, 4]])
m_vec = m.vec()
assert m_vec.cols == 1
for i in range(4):
assert m_vec[i] == i + 1
def test_vech():
m = Matrix([[1, 2], [2, 3]])
m_vech = m.vech()
assert m_vech.cols == 1
for i in range(3):
assert m_vech[i] == i + 1
m_vech = m.vech(diagonal=False)
assert m_vech[0] == 2
m = Matrix([[1, x*(x + y)], [y*x + x**2, 1]])
m_vech = m.vech(diagonal=False)
assert m_vech[0] == x*(x + y)
m = Matrix([[1, x*(x + y)], [y*x, 1]])
m_vech = m.vech(diagonal=False, check_symmetry=False)
assert m_vech[0] == y*x
def test_vech_errors():
m = Matrix([[1, 3]])
raises(ShapeError, lambda: m.vech())
m = Matrix([[1, 3], [2, 4]])
raises(ValueError, lambda: m.vech())
raises(ShapeError, lambda: Matrix([ [1, 3] ]).vech())
raises(ValueError, lambda: Matrix([ [1, 3], [2, 4] ]).vech())
def test_diag():
a = Matrix([[1, 2], [2, 3]])
b = Matrix([[3, x], [y, 3]])
c = Matrix([[3, x, 3], [y, 3, z], [x, y, z]])
assert diag(a, b, b) == Matrix([
[1, 2, 0, 0, 0, 0],
[2, 3, 0, 0, 0, 0],
[0, 0, 3, x, 0, 0],
[0, 0, y, 3, 0, 0],
[0, 0, 0, 0, 3, x],
[0, 0, 0, 0, y, 3],
])
assert diag(a, b, c) == Matrix([
[1, 2, 0, 0, 0, 0, 0],
[2, 3, 0, 0, 0, 0, 0],
[0, 0, 3, x, 0, 0, 0],
[0, 0, y, 3, 0, 0, 0],
[0, 0, 0, 0, 3, x, 3],
[0, 0, 0, 0, y, 3, z],
[0, 0, 0, 0, x, y, z],
])
assert diag(a, c, b) == Matrix([
[1, 2, 0, 0, 0, 0, 0],
[2, 3, 0, 0, 0, 0, 0],
[0, 0, 3, x, 3, 0, 0],
[0, 0, y, 3, z, 0, 0],
[0, 0, x, y, z, 0, 0],
[0, 0, 0, 0, 0, 3, x],
[0, 0, 0, 0, 0, y, 3],
])
a = Matrix([x, y, z])
b = Matrix([[1, 2], [3, 4]])
c = Matrix([[5, 6]])
assert diag(a, 7, b, c) == Matrix([
[x, 0, 0, 0, 0, 0],
[y, 0, 0, 0, 0, 0],
[z, 0, 0, 0, 0, 0],
[0, 7, 0, 0, 0, 0],
[0, 0, 1, 2, 0, 0],
[0, 0, 3, 4, 0, 0],
[0, 0, 0, 0, 5, 6],
])
assert diag(1, [2, 3], [[4, 5]]) == Matrix([
[1, 0, 0, 0],
[0, 2, 0, 0],
[0, 3, 0, 0],
[0, 0, 4, 5]])
def test_get_diag_blocks1():
a = Matrix([[1, 2], [2, 3]])
b = Matrix([[3, x], [y, 3]])
c = Matrix([[3, x, 3], [y, 3, z], [x, y, z]])
assert a.get_diag_blocks() == [a]
assert b.get_diag_blocks() == [b]
assert c.get_diag_blocks() == [c]
def test_get_diag_blocks2():
a = Matrix([[1, 2], [2, 3]])
b = Matrix([[3, x], [y, 3]])
c = Matrix([[3, x, 3], [y, 3, z], [x, y, z]])
assert diag(a, b, b).get_diag_blocks() == [a, b, b]
assert diag(a, b, c).get_diag_blocks() == [a, b, c]
assert diag(a, c, b).get_diag_blocks() == [a, c, b]
assert diag(c, c, b).get_diag_blocks() == [c, c, b]
def test_inv_block():
a = Matrix([[1, 2], [2, 3]])
b = Matrix([[3, x], [y, 3]])
c = Matrix([[3, x, 3], [y, 3, z], [x, y, z]])
A = diag(a, b, b)
assert A.inv(try_block_diag=True) == diag(a.inv(), b.inv(), b.inv())
A = diag(a, b, c)
assert A.inv(try_block_diag=True) == diag(a.inv(), b.inv(), c.inv())
A = diag(a, c, b)
assert A.inv(try_block_diag=True) == diag(a.inv(), c.inv(), b.inv())
A = diag(a, a, b, a, c, a)
assert A.inv(try_block_diag=True) == diag(
a.inv(), a.inv(), b.inv(), a.inv(), c.inv(), a.inv())
assert A.inv(try_block_diag=True, method="ADJ") == diag(
a.inv(method="ADJ"), a.inv(method="ADJ"), b.inv(method="ADJ"),
a.inv(method="ADJ"), c.inv(method="ADJ"), a.inv(method="ADJ"))
def test_creation_args():
"""
Check that matrix dimensions can be specified using any reasonable type
(see issue 4614).
"""
raises(ValueError, lambda: zeros(3, -1))
raises(TypeError, lambda: zeros(1, 2, 3, 4))
assert zeros(long(3)) == zeros(3)
assert zeros(Integer(3)) == zeros(3)
assert zeros(3.) == zeros(3)
assert eye(long(3)) == eye(3)
assert eye(Integer(3)) == eye(3)
assert eye(3.) == eye(3)
assert ones(long(3), Integer(4)) == ones(3, 4)
raises(TypeError, lambda: Matrix(5))
raises(TypeError, lambda: Matrix(1, 2))
def test_diagonal_symmetrical():
m = Matrix(2, 2, [0, 1, 1, 0])
assert not m.is_diagonal()
assert m.is_symmetric()
assert m.is_symmetric(simplify=False)
m = Matrix(2, 2, [1, 0, 0, 1])
assert m.is_diagonal()
m = diag(1, 2, 3)
assert m.is_diagonal()
assert m.is_symmetric()
m = Matrix(3, 3, [1, 0, 0, 0, 2, 0, 0, 0, 3])
assert m == diag(1, 2, 3)
m = Matrix(2, 3, zeros(2, 3))
assert not m.is_symmetric()
assert m.is_diagonal()
m = Matrix(((5, 0), (0, 6), (0, 0)))
assert m.is_diagonal()
m = Matrix(((5, 0, 0), (0, 6, 0)))
assert m.is_diagonal()
m = Matrix(3, 3, [1, x**2 + 2*x + 1, y, (x + 1)**2, 2, 0, y, 0, 3])
assert m.is_symmetric()
assert not m.is_symmetric(simplify=False)
assert m.expand().is_symmetric(simplify=False)
def test_diagonalization():
m = Matrix(3, 2, [-3, 1, -3, 20, 3, 10])
assert not m.is_diagonalizable()
assert not m.is_symmetric()
raises(NonSquareMatrixError, lambda: m.diagonalize())
# diagonalizable
m = diag(1, 2, 3)
(P, D) = m.diagonalize()
assert P == eye(3)
assert D == m
m = Matrix(2, 2, [0, 1, 1, 0])
assert m.is_symmetric()
assert m.is_diagonalizable()
(P, D) = m.diagonalize()
assert P.inv() * m * P == D
m = Matrix(2, 2, [1, 0, 0, 3])
assert m.is_symmetric()
assert m.is_diagonalizable()
(P, D) = m.diagonalize()
assert P.inv() * m * P == D
assert P == eye(2)
assert D == m
m = Matrix(2, 2, [1, 1, 0, 0])
assert m.is_diagonalizable()
(P, D) = m.diagonalize()
assert P.inv() * m * P == D
m = Matrix(3, 3, [1, 2, 0, 0, 3, 0, 2, -4, 2])
assert m.is_diagonalizable()
(P, D) = m.diagonalize()
assert P.inv() * m * P == D
for i in P:
assert i.as_numer_denom()[1] == 1
m = Matrix(2, 2, [1, 0, 0, 0])
assert m.is_diagonal()
assert m.is_diagonalizable()
(P, D) = m.diagonalize()
assert P.inv() * m * P == D
assert P == Matrix([[0, 1], [1, 0]])
# diagonalizable, complex only
m = Matrix(2, 2, [0, 1, -1, 0])
assert not m.is_diagonalizable(True)
raises(MatrixError, lambda: m.diagonalize(True))
assert m.is_diagonalizable()
(P, D) = m.diagonalize()
assert P.inv() * m * P == D
# not diagonalizable
m = Matrix(2, 2, [0, 1, 0, 0])
assert not m.is_diagonalizable()
raises(MatrixError, lambda: m.diagonalize())
m = Matrix(3, 3, [-3, 1, -3, 20, 3, 10, 2, -2, 4])
assert not m.is_diagonalizable()
raises(MatrixError, lambda: m.diagonalize())
# symbolic
a, b, c, d = symbols('a b c d')
m = Matrix(2, 2, [a, c, c, b])
assert m.is_symmetric()
assert m.is_diagonalizable()
@XFAIL
def test_eigen_vects():
m = Matrix(2, 2, [1, 0, 0, I])
raises(NotImplementedError, lambda: m.is_diagonalizable(True))
# !!! bug because of eigenvects() or roots(x**2 + (-1 - I)*x + I, x)
# see issue 5292
assert not m.is_diagonalizable(True)
raises(MatrixError, lambda: m.diagonalize(True))
(P, D) = m.diagonalize(True)
def test_jordan_form():
m = Matrix(3, 2, [-3, 1, -3, 20, 3, 10])
raises(NonSquareMatrixError, lambda: m.jordan_form())
# diagonalizable
m = Matrix(3, 3, [7, -12, 6, 10, -19, 10, 12, -24, 13])
Jmust = Matrix(3, 3, [-1, 0, 0, 0, 1, 0, 0, 0, 1])
P, J = m.jordan_form()
assert Jmust == J
assert Jmust == m.diagonalize()[1]
# m = Matrix(3, 3, [0, 6, 3, 1, 3, 1, -2, 2, 1])
# m.jordan_form() # very long
# m.jordan_form() #
# diagonalizable, complex only
# Jordan cells
# complexity: one of eigenvalues is zero
m = Matrix(3, 3, [0, 1, 0, -4, 4, 0, -2, 1, 2])
# The blocks are ordered according to the value of their eigenvalues,
# in order to make the matrix compatible with .diagonalize()
Jmust = Matrix(3, 3, [2, 1, 0, 0, 2, 0, 0, 0, 2])
P, J = m.jordan_form()
assert Jmust == J
# complexity: all of eigenvalues are equal
m = Matrix(3, 3, [2, 6, -15, 1, 1, -5, 1, 2, -6])
# Jmust = Matrix(3, 3, [-1, 0, 0, 0, -1, 1, 0, 0, -1])
# same here see 1456ff
Jmust = Matrix(3, 3, [-1, 1, 0, 0, -1, 0, 0, 0, -1])
P, J = m.jordan_form()
assert Jmust == J
# complexity: two of eigenvalues are zero
m = Matrix(3, 3, [4, -5, 2, 5, -7, 3, 6, -9, 4])
Jmust = Matrix(3, 3, [0, 1, 0, 0, 0, 0, 0, 0, 1])
P, J = m.jordan_form()
assert Jmust == J
m = Matrix(4, 4, [6, 5, -2, -3, -3, -1, 3, 3, 2, 1, -2, -3, -1, 1, 5, 5])
Jmust = Matrix(4, 4, [2, 1, 0, 0,
0, 2, 0, 0,
0, 0, 2, 1,
0, 0, 0, 2]
)
P, J = m.jordan_form()
assert Jmust == J
m = Matrix(4, 4, [6, 2, -8, -6, -3, 2, 9, 6, 2, -2, -8, -6, -1, 0, 3, 4])
# Jmust = Matrix(4, 4, [2, 0, 0, 0, 0, 2, 1, 0, 0, 0, 2, 0, 0, 0, 0, -2])
# same here see 1456ff
Jmust = Matrix(4, 4, [-2, 0, 0, 0,
0, 2, 1, 0,
0, 0, 2, 0,
0, 0, 0, 2])
P, J = m.jordan_form()
assert Jmust == J
m = Matrix(4, 4, [5, 4, 2, 1, 0, 1, -1, -1, -1, -1, 3, 0, 1, 1, -1, 2])
assert not m.is_diagonalizable()
Jmust = Matrix(4, 4, [1, 0, 0, 0, 0, 2, 0, 0, 0, 0, 4, 1, 0, 0, 0, 4])
P, J = m.jordan_form()
assert Jmust == J
# checking for maximum precision to remain unchanged
m = Matrix([[Float('1.0', precision=110), Float('2.0', precision=110)],
[Float('3.14159265358979323846264338327', precision=110), Float('4.0', precision=110)]])
P, J = m.jordan_form()
for term in J._mat:
if isinstance(term, Float):
assert term._prec == 110
def test_jordan_form_complex_issue_9274():
A = Matrix([[ 2, 4, 1, 0],
[-4, 2, 0, 1],
[ 0, 0, 2, 4],
[ 0, 0, -4, 2]])
p = 2 - 4*I;
q = 2 + 4*I;
Jmust1 = Matrix([[p, 1, 0, 0],
[0, p, 0, 0],
[0, 0, q, 1],
[0, 0, 0, q]])
Jmust2 = Matrix([[q, 1, 0, 0],
[0, q, 0, 0],
[0, 0, p, 1],
[0, 0, 0, p]])
P, J = A.jordan_form()
assert J == Jmust1 or J == Jmust2
assert simplify(P*J*P.inv()) == A
def test_issue_10220():
# two non-orthogonal Jordan blocks with eigenvalue 1
M = Matrix([[1, 0, 0, 1],
[0, 1, 1, 0],
[0, 0, 1, 1],
[0, 0, 0, 1]])
P, J = M.jordan_form()
assert P == Matrix([[0, 1, 0, 1],
[1, 0, 0, 0],
[0, 1, 0, 0],
[0, 0, 1, 0]])
assert J == Matrix([
[1, 1, 0, 0],
[0, 1, 1, 0],
[0, 0, 1, 0],
[0, 0, 0, 1]])
def test_Matrix_berkowitz_charpoly():
UA, K_i, K_w = symbols('UA K_i K_w')
A = Matrix([[-K_i - UA + K_i**2/(K_i + K_w), K_i*K_w/(K_i + K_w)],
[ K_i*K_w/(K_i + K_w), -K_w + K_w**2/(K_i + K_w)]])
charpoly = A.charpoly(x)
assert charpoly == \
Poly(x**2 + (K_i*UA + K_w*UA + 2*K_i*K_w)/(K_i + K_w)*x +
K_i*K_w*UA/(K_i + K_w), x, domain='ZZ(K_i,K_w,UA)')
assert type(charpoly) is PurePoly
A = Matrix([[1, 3], [2, 0]])
assert A.charpoly() == A.charpoly(x) == PurePoly(x**2 - x - 6)
A = Matrix([[1, 2], [x, 0]])
p = A.charpoly(x)
assert p.gen != x
assert p.as_expr().subs(p.gen, x) == x**2 - 3*x
def test_exp():
m = Matrix([[3, 4], [0, -2]])
m_exp = Matrix([[exp(3), -4*exp(-2)/5 + 4*exp(3)/5], [0, exp(-2)]])
assert m.exp() == m_exp
assert exp(m) == m_exp
m = Matrix([[1, 0], [0, 1]])
assert m.exp() == Matrix([[E, 0], [0, E]])
assert exp(m) == Matrix([[E, 0], [0, E]])
m = Matrix([[1, -1], [1, 1]])
assert m.exp() == Matrix([[E*cos(1), -E*sin(1)], [E*sin(1), E*cos(1)]])
def test_has():
A = Matrix(((x, y), (2, 3)))
assert A.has(x)
assert not A.has(z)
assert A.has(Symbol)
A = A.subs(x, 2)
assert not A.has(x)
def test_LUdecomposition_Simple_iszerofunc():
# Test if callable passed to matrices.LUdecomposition_Simple() as iszerofunc keyword argument is used inside
# matrices.LUdecomposition_Simple()
magic_string = "I got passed in!"
def goofyiszero(value):
raise ValueError(magic_string)
try:
lu, p = Matrix([[1, 0], [0, 1]]).LUdecomposition_Simple(iszerofunc=goofyiszero)
except ValueError as err:
assert magic_string == err.args[0]
return
assert False
def test_LUdecomposition_iszerofunc():
# Test if callable passed to matrices.LUdecomposition() as iszerofunc keyword argument is used inside
# matrices.LUdecomposition_Simple()
magic_string = "I got passed in!"
def goofyiszero(value):
raise ValueError(magic_string)
try:
l, u, p = Matrix([[1, 0], [0, 1]]).LUdecomposition(iszerofunc=goofyiszero)
except ValueError as err:
assert magic_string == err.args[0]
return
assert False
def test_find_reasonable_pivot_naive_finds_guaranteed_nonzero1():
# Test if matrices._find_reasonable_pivot_naive()
# finds a guaranteed non-zero pivot when the
# some of the candidate pivots are symbolic expressions.
# Keyword argument: simpfunc=None indicates that no simplifications
# should be performed during the search.
x = Symbol('x')
column = Matrix(3, 1, [x, cos(x)**2 + sin(x)**2, Rational(1, 2)])
pivot_offset, pivot_val, pivot_assumed_nonzero, simplified =\
_find_reasonable_pivot_naive(column)
assert pivot_val == Rational(1, 2)
def test_find_reasonable_pivot_naive_finds_guaranteed_nonzero2():
# Test if matrices._find_reasonable_pivot_naive()
# finds a guaranteed non-zero pivot when the
# some of the candidate pivots are symbolic expressions.
# Keyword argument: simpfunc=_simplify indicates that the search
# should attempt to simplify candidate pivots.
x = Symbol('x')
column = Matrix(3, 1,
[x,
cos(x)**2+sin(x)**2+x**2,
cos(x)**2+sin(x)**2])
pivot_offset, pivot_val, pivot_assumed_nonzero, simplified =\
_find_reasonable_pivot_naive(column, simpfunc=_simplify)
assert pivot_val == 1
def test_find_reasonable_pivot_naive_simplifies():
# Test if matrices._find_reasonable_pivot_naive()
# simplifies candidate pivots, and reports
# their offsets correctly.
x = Symbol('x')
column = Matrix(3, 1,
[x,
cos(x)**2+sin(x)**2+x,
cos(x)**2+sin(x)**2])
pivot_offset, pivot_val, pivot_assumed_nonzero, simplified =\
_find_reasonable_pivot_naive(column, simpfunc=_simplify)
assert len(simplified) == 2
assert simplified[0][0] == 1
assert simplified[0][1] == 1+x
assert simplified[1][0] == 2
assert simplified[1][1] == 1
def test_errors():
raises(ValueError, lambda: Matrix([[1, 2], [1]]))
raises(IndexError, lambda: Matrix([[1, 2]])[1.2, 5])
raises(IndexError, lambda: Matrix([[1, 2]])[1, 5.2])
raises(ValueError, lambda: randMatrix(3, c=4, symmetric=True))
raises(ValueError, lambda: Matrix([1, 2]).reshape(4, 6))
raises(ShapeError,
lambda: Matrix([[1, 2], [3, 4]]).copyin_matrix([1, 0], Matrix([1, 2])))
raises(TypeError, lambda: Matrix([[1, 2], [3, 4]]).copyin_list([0,
1], set([])))
raises(NonSquareMatrixError, lambda: Matrix([[1, 2, 3], [2, 3, 0]]).inv())
raises(ShapeError,
lambda: Matrix(1, 2, [1, 2]).row_join(Matrix([[1, 2], [3, 4]])))
raises(
ShapeError, lambda: Matrix([1, 2]).col_join(Matrix([[1, 2], [3, 4]])))
raises(ShapeError, lambda: Matrix([1]).row_insert(1, Matrix([[1,
2], [3, 4]])))
raises(ShapeError, lambda: Matrix([1]).col_insert(1, Matrix([[1,
2], [3, 4]])))
raises(NonSquareMatrixError, lambda: Matrix([1, 2]).trace())
raises(TypeError, lambda: Matrix([1]).applyfunc(1))
raises(ShapeError, lambda: Matrix([1]).LUsolve(Matrix([[1, 2], [3, 4]])))
raises(ValueError, lambda: Matrix([[1, 2], [3, 4]]).minor(4, 5))
raises(ValueError, lambda: Matrix([[1, 2], [3, 4]]).minor_submatrix(4, 5))
raises(TypeError, lambda: Matrix([1, 2, 3]).cross(1))
raises(TypeError, lambda: Matrix([1, 2, 3]).dot(1))
raises(ShapeError, lambda: Matrix([1, 2, 3]).dot(Matrix([1, 2])))
raises(ShapeError, lambda: Matrix([1, 2]).dot([]))
raises(TypeError, lambda: Matrix([1, 2]).dot('a'))
with warns_deprecated_sympy():
Matrix([[1, 2], [3, 4]]).dot(Matrix([[4, 3], [1, 2]]))
raises(ShapeError, lambda: Matrix([1, 2]).dot([1, 2, 3]))
raises(NonSquareMatrixError, lambda: Matrix([1, 2, 3]).exp())
raises(ShapeError, lambda: Matrix([[1, 2], [3, 4]]).normalized())
raises(ValueError, lambda: Matrix([1, 2]).inv(method='not a method'))
raises(NonSquareMatrixError, lambda: Matrix([1, 2]).inverse_GE())
raises(ValueError, lambda: Matrix([[1, 2], [1, 2]]).inverse_GE())
raises(NonSquareMatrixError, lambda: Matrix([1, 2]).inverse_ADJ())
raises(ValueError, lambda: Matrix([[1, 2], [1, 2]]).inverse_ADJ())
raises(NonSquareMatrixError, lambda: Matrix([1, 2]).inverse_LU())
raises(NonSquareMatrixError, lambda: Matrix([1, 2]).is_nilpotent())
raises(NonSquareMatrixError, lambda: Matrix([1, 2]).det())
raises(ValueError,
lambda: Matrix([[1, 2], [3, 4]]).det(method='Not a real method'))
raises(ValueError,
lambda: Matrix([[1, 2, 3, 4], [5, 6, 7, 8],
[9, 10, 11, 12], [13, 14, 15, 16]]).det(iszerofunc="Not function"))
raises(ValueError,
lambda: Matrix([[1, 2, 3, 4], [5, 6, 7, 8],
[9, 10, 11, 12], [13, 14, 15, 16]]).det(iszerofunc=False))
raises(ValueError,
lambda: hessian(Matrix([[1, 2], [3, 4]]), Matrix([[1, 2], [2, 1]])))
raises(ValueError, lambda: hessian(Matrix([[1, 2], [3, 4]]), []))
raises(ValueError, lambda: hessian(Symbol('x')**2, 'a'))
raises(IndexError, lambda: eye(3)[5, 2])
raises(IndexError, lambda: eye(3)[2, 5])
M = Matrix(((1, 2, 3, 4), (5, 6, 7, 8), (9, 10, 11, 12), (13, 14, 15, 16)))
raises(ValueError, lambda: M.det('method=LU_decomposition()'))
V = Matrix([[10, 10, 10]])
M = Matrix([[1, 2, 3], [2, 3, 4], [3, 4, 5]])
raises(ValueError, lambda: M.row_insert(4.7, V))
M = Matrix([[1, 2, 3], [2, 3, 4], [3, 4, 5]])
raises(ValueError, lambda: M.col_insert(-4.2, V))
def test_len():
assert len(Matrix()) == 0
assert len(Matrix([[1, 2]])) == len(Matrix([[1], [2]])) == 2
assert len(Matrix(0, 2, lambda i, j: 0)) == \
len(Matrix(2, 0, lambda i, j: 0)) == 0
assert len(Matrix([[0, 1, 2], [3, 4, 5]])) == 6
assert Matrix([1]) == Matrix([[1]])
assert not Matrix()
assert Matrix() == Matrix([])
def test_integrate():
A = Matrix(((1, 4, x), (y, 2, 4), (10, 5, x**2)))
assert A.integrate(x) == \
Matrix(((x, 4*x, x**2/2), (x*y, 2*x, 4*x), (10*x, 5*x, x**3/3)))
assert A.integrate(y) == \
Matrix(((y, 4*y, x*y), (y**2/2, 2*y, 4*y), (10*y, 5*y, y*x**2)))
def test_limit():
A = Matrix(((1, 4, sin(x)/x), (y, 2, 4), (10, 5, x**2 + 1)))
assert A.limit(x, 0) == Matrix(((1, 4, 1), (y, 2, 4), (10, 5, 1)))
def test_diff():
A = MutableDenseMatrix(((1, 4, x), (y, 2, 4), (10, 5, x**2 + 1)))
assert isinstance(A.diff(x), type(A))
assert A.diff(x) == MutableDenseMatrix(((0, 0, 1), (0, 0, 0), (0, 0, 2*x)))
assert A.diff(y) == MutableDenseMatrix(((0, 0, 0), (1, 0, 0), (0, 0, 0)))
assert diff(A, x) == MutableDenseMatrix(((0, 0, 1), (0, 0, 0), (0, 0, 2*x)))
assert diff(A, y) == MutableDenseMatrix(((0, 0, 0), (1, 0, 0), (0, 0, 0)))
A_imm = A.as_immutable()
assert isinstance(A_imm.diff(x), type(A_imm))
assert A_imm.diff(x) == ImmutableDenseMatrix(((0, 0, 1), (0, 0, 0), (0, 0, 2*x)))
assert A_imm.diff(y) == ImmutableDenseMatrix(((0, 0, 0), (1, 0, 0), (0, 0, 0)))
assert diff(A_imm, x) == ImmutableDenseMatrix(((0, 0, 1), (0, 0, 0), (0, 0, 2*x)))
assert diff(A_imm, y) == ImmutableDenseMatrix(((0, 0, 0), (1, 0, 0), (0, 0, 0)))
def test_diff_by_matrix():
# Derive matrix by matrix:
A = MutableDenseMatrix([[x, y], [z, t]])
assert A.diff(A) == Array([[[[1, 0], [0, 0]], [[0, 1], [0, 0]]], [[[0, 0], [1, 0]], [[0, 0], [0, 1]]]])
assert diff(A, A) == Array([[[[1, 0], [0, 0]], [[0, 1], [0, 0]]], [[[0, 0], [1, 0]], [[0, 0], [0, 1]]]])
A_imm = A.as_immutable()
assert A_imm.diff(A_imm) == Array([[[[1, 0], [0, 0]], [[0, 1], [0, 0]]], [[[0, 0], [1, 0]], [[0, 0], [0, 1]]]])
assert diff(A_imm, A_imm) == Array([[[[1, 0], [0, 0]], [[0, 1], [0, 0]]], [[[0, 0], [1, 0]], [[0, 0], [0, 1]]]])
# Derive a constant matrix:
assert A.diff(a) == MutableDenseMatrix([[0, 0], [0, 0]])
B = ImmutableDenseMatrix([a, b])
assert A.diff(B) == A.zeros(2)
# Test diff with tuples:
dB = B.diff([[a, b]])
assert dB.shape == (2, 2, 1)
assert dB == Array([[[1], [0]], [[0], [1]]])
f = Function("f")
fxyz = f(x, y, z)
assert fxyz.diff([[x, y, z]]) == Array([fxyz.diff(x), fxyz.diff(y), fxyz.diff(z)])
assert fxyz.diff(([x, y, z], 2)) == Array([
[fxyz.diff(x, 2), fxyz.diff(x, y), fxyz.diff(x, z)],
[fxyz.diff(x, y), fxyz.diff(y, 2), fxyz.diff(y, z)],
[fxyz.diff(x, z), fxyz.diff(z, y), fxyz.diff(z, 2)],
])
expr = sin(x)*exp(y)
assert expr.diff([[x, y]]) == Array([cos(x)*exp(y), sin(x)*exp(y)])
assert expr.diff(y, ((x, y),)) == Array([cos(x)*exp(y), sin(x)*exp(y)])
assert expr.diff(x, ((x, y),)) == Array([-sin(x)*exp(y), cos(x)*exp(y)])
assert expr.diff(((y, x),), [[x, y]]) == Array([[cos(x)*exp(y), -sin(x)*exp(y)], [sin(x)*exp(y), cos(x)*exp(y)]])
# Test different notations:
fxyz.diff(x).diff(y).diff(x) == fxyz.diff(((x, y, z),), 3)[0, 1, 0]
fxyz.diff(z).diff(y).diff(x) == fxyz.diff(((x, y, z),), 3)[2, 1, 0]
fxyz.diff([[x, y, z]], ((z, y, x),)) == Array([[fxyz.diff(i).diff(j) for i in (x, y, z)] for j in (z, y, x)])
# Test scalar derived by matrix remains matrix:
res = x.diff(Matrix([[x, y]]))
assert isinstance(res, ImmutableDenseMatrix)
assert res == Matrix([[1, 0]])
res = (x**3).diff(Matrix([[x, y]]))
assert isinstance(res, ImmutableDenseMatrix)
assert res == Matrix([[3*x**2, 0]])
def test_getattr():
A = Matrix(((1, 4, x), (y, 2, 4), (10, 5, x**2 + 1)))
raises(AttributeError, lambda: A.nonexistantattribute)
assert getattr(A, 'diff')(x) == Matrix(((0, 0, 1), (0, 0, 0), (0, 0, 2*x)))
def test_hessenberg():
A = Matrix([[3, 4, 1], [2, 4, 5], [0, 1, 2]])
assert A.is_upper_hessenberg
A = A.T
assert A.is_lower_hessenberg
A[0, -1] = 1
assert A.is_lower_hessenberg is False
A = Matrix([[3, 4, 1], [2, 4, 5], [3, 1, 2]])
assert not A.is_upper_hessenberg
A = zeros(5, 2)
assert A.is_upper_hessenberg
def test_cholesky():
raises(NonSquareMatrixError, lambda: Matrix((1, 2)).cholesky())
raises(ValueError, lambda: Matrix(((1, 2), (3, 4))).cholesky())
raises(ValueError, lambda: Matrix(((5 + I, 0), (0, 1))).cholesky())
raises(ValueError, lambda: Matrix(((1, 5), (5, 1))).cholesky())
raises(ValueError, lambda: Matrix(((1, 2), (3, 4))).cholesky(hermitian=False))
assert Matrix(((5 + I, 0), (0, 1))).cholesky(hermitian=False) == Matrix([
[sqrt(5 + I), 0], [0, 1]])
A = Matrix(((1, 5), (5, 1)))
L = A.cholesky(hermitian=False)
assert L == Matrix([[1, 0], [5, 2*sqrt(6)*I]])
assert L*L.T == A
A = Matrix(((25, 15, -5), (15, 18, 0), (-5, 0, 11)))
L = A.cholesky()
assert L * L.T == A
assert L.is_lower
assert L == Matrix([[5, 0, 0], [3, 3, 0], [-1, 1, 3]])
A = Matrix(((4, -2*I, 2 + 2*I), (2*I, 2, -1 + I), (2 - 2*I, -1 - I, 11)))
assert A.cholesky() == Matrix(((2, 0, 0), (I, 1, 0), (1 - I, 0, 3)))
def test_LDLdecomposition():
raises(NonSquareMatrixError, lambda: Matrix((1, 2)).LDLdecomposition())
raises(ValueError, lambda: Matrix(((1, 2), (3, 4))).LDLdecomposition())
raises(ValueError, lambda: Matrix(((5 + I, 0), (0, 1))).LDLdecomposition())
raises(ValueError, lambda: Matrix(((1, 5), (5, 1))).LDLdecomposition())
raises(ValueError, lambda: Matrix(((1, 2), (3, 4))).LDLdecomposition(hermitian=False))
A = Matrix(((1, 5), (5, 1)))
L, D = A.LDLdecomposition(hermitian=False)
assert L * D * L.T == A
A = Matrix(((25, 15, -5), (15, 18, 0), (-5, 0, 11)))
L, D = A.LDLdecomposition()
assert L * D * L.T == A
assert L.is_lower
assert L == Matrix([[1, 0, 0], [ S(3)/5, 1, 0], [S(-1)/5, S(1)/3, 1]])
assert D.is_diagonal()
assert D == Matrix([[25, 0, 0], [0, 9, 0], [0, 0, 9]])
A = Matrix(((4, -2*I, 2 + 2*I), (2*I, 2, -1 + I), (2 - 2*I, -1 - I, 11)))
L, D = A.LDLdecomposition()
assert expand_mul(L * D * L.H) == A
assert L == Matrix(((1, 0, 0), (I/2, 1, 0), (S(1)/2 - I/2, 0, 1)))
assert D == Matrix(((4, 0, 0), (0, 1, 0), (0, 0, 9)))
def test_cholesky_solve():
A = Matrix([[2, 3, 5],
[3, 6, 2],
[8, 3, 6]])
x = Matrix(3, 1, [3, 7, 5])
b = A*x
soln = A.cholesky_solve(b)
assert soln == x
A = Matrix([[0, -1, 2],
[5, 10, 7],
[8, 3, 4]])
x = Matrix(3, 1, [-1, 2, 5])
b = A*x
soln = A.cholesky_solve(b)
assert soln == x
A = Matrix(((1, 5), (5, 1)))
x = Matrix((4, -3))
b = A*x
soln = A.cholesky_solve(b)
assert soln == x
A = Matrix(((9, 3*I), (-3*I, 5)))
x = Matrix((-2, 1))
b = A*x
soln = A.cholesky_solve(b)
assert expand_mul(soln) == x
A = Matrix(((9*I, 3), (-3 + I, 5)))
x = Matrix((2 + 3*I, -1))
b = A*x
soln = A.cholesky_solve(b)
assert expand_mul(soln) == x
a00, a01, a11, b0, b1 = symbols('a00, a01, a11, b0, b1')
A = Matrix(((a00, a01), (a01, a11)))
b = Matrix((b0, b1))
x = A.cholesky_solve(b)
assert simplify(A*x) == b
def test_LDLsolve():
A = Matrix([[2, 3, 5],
[3, 6, 2],
[8, 3, 6]])
x = Matrix(3, 1, [3, 7, 5])
b = A*x
soln = A.LDLsolve(b)
assert soln == x
A = Matrix([[0, -1, 2],
[5, 10, 7],
[8, 3, 4]])
x = Matrix(3, 1, [-1, 2, 5])
b = A*x
soln = A.LDLsolve(b)
assert soln == x
A = Matrix(((9, 3*I), (-3*I, 5)))
x = Matrix((-2, 1))
b = A*x
soln = A.LDLsolve(b)
assert expand_mul(soln) == x
A = Matrix(((9*I, 3), (-3 + I, 5)))
x = Matrix((2 + 3*I, -1))
b = A*x
soln = A.cholesky_solve(b)
assert expand_mul(soln) == x
def test_lower_triangular_solve():
raises(NonSquareMatrixError,
lambda: Matrix([1, 0]).lower_triangular_solve(Matrix([0, 1])))
raises(ShapeError,
lambda: Matrix([[1, 0], [0, 1]]).lower_triangular_solve(Matrix([1])))
raises(ValueError,
lambda: Matrix([[2, 1], [1, 2]]).lower_triangular_solve(
Matrix([[1, 0], [0, 1]])))
A = Matrix([[1, 0], [0, 1]])
B = Matrix([[x, y], [y, x]])
C = Matrix([[4, 8], [2, 9]])
assert A.lower_triangular_solve(B) == B
assert A.lower_triangular_solve(C) == C
def test_upper_triangular_solve():
raises(NonSquareMatrixError,
lambda: Matrix([1, 0]).upper_triangular_solve(Matrix([0, 1])))
raises(TypeError,
lambda: Matrix([[1, 0], [0, 1]]).upper_triangular_solve(Matrix([1])))
raises(TypeError,
lambda: Matrix([[2, 1], [1, 2]]).upper_triangular_solve(
Matrix([[1, 0], [0, 1]])))
A = Matrix([[1, 0], [0, 1]])
B = Matrix([[x, y], [y, x]])
C = Matrix([[2, 4], [3, 8]])
assert A.upper_triangular_solve(B) == B
assert A.upper_triangular_solve(C) == C
def test_diagonal_solve():
raises(TypeError, lambda: Matrix([1, 1]).diagonal_solve(Matrix([1])))
A = Matrix([[1, 0], [0, 1]])*2
B = Matrix([[x, y], [y, x]])
assert A.diagonal_solve(B) == B/2
def test_matrix_norm():
# Vector Tests
# Test columns and symbols
x = Symbol('x', real=True)
v = Matrix([cos(x), sin(x)])
assert trigsimp(v.norm(2)) == 1
assert v.norm(10) == Pow(cos(x)**10 + sin(x)**10, S(1)/10)
# Test Rows
A = Matrix([[5, Rational(3, 2)]])
assert A.norm() == Pow(25 + Rational(9, 4), S(1)/2)
assert A.norm(oo) == max(A._mat)
assert A.norm(-oo) == min(A._mat)
# Matrix Tests
# Intuitive test
A = Matrix([[1, 1], [1, 1]])
assert A.norm(2) == 2
assert A.norm(-2) == 0
assert A.norm('frobenius') == 2
assert eye(10).norm(2) == eye(10).norm(-2) == 1
assert A.norm(oo) == 2
# Test with Symbols and more complex entries
A = Matrix([[3, y, y], [x, S(1)/2, -pi]])
assert (A.norm('fro')
== sqrt(S(37)/4 + 2*abs(y)**2 + pi**2 + x**2))
# Check non-square
A = Matrix([[1, 2, -3], [4, 5, Rational(13, 2)]])
assert A.norm(2) == sqrt(S(389)/8 + sqrt(78665)/8)
assert A.norm(-2) == S(0)
assert A.norm('frobenius') == sqrt(389)/2
# Test properties of matrix norms
# https://en.wikipedia.org/wiki/Matrix_norm#Definition
# Two matrices
A = Matrix([[1, 2], [3, 4]])
B = Matrix([[5, 5], [-2, 2]])
C = Matrix([[0, -I], [I, 0]])
D = Matrix([[1, 0], [0, -1]])
L = [A, B, C, D]
alpha = Symbol('alpha', real=True)
for order in ['fro', 2, -2]:
# Zero Check
assert zeros(3).norm(order) == S(0)
# Check Triangle Inequality for all Pairs of Matrices
for X in L:
for Y in L:
dif = (X.norm(order) + Y.norm(order) -
(X + Y).norm(order))
assert (dif >= 0)
# Scalar multiplication linearity
for M in [A, B, C, D]:
dif = simplify((alpha*M).norm(order) -
abs(alpha) * M.norm(order))
assert dif == 0
# Test Properties of Vector Norms
# https://en.wikipedia.org/wiki/Vector_norm
# Two column vectors
a = Matrix([1, 1 - 1*I, -3])
b = Matrix([S(1)/2, 1*I, 1])
c = Matrix([-1, -1, -1])
d = Matrix([3, 2, I])
e = Matrix([Integer(1e2), Rational(1, 1e2), 1])
L = [a, b, c, d, e]
alpha = Symbol('alpha', real=True)
for order in [1, 2, -1, -2, S.Infinity, S.NegativeInfinity, pi]:
# Zero Check
if order > 0:
assert Matrix([0, 0, 0]).norm(order) == S(0)
# Triangle inequality on all pairs
if order >= 1: # Triangle InEq holds only for these norms
for X in L:
for Y in L:
dif = (X.norm(order) + Y.norm(order) -
(X + Y).norm(order))
assert simplify(dif >= 0) is S.true
# Linear to scalar multiplication
if order in [1, 2, -1, -2, S.Infinity, S.NegativeInfinity]:
for X in L:
dif = simplify((alpha*X).norm(order) -
(abs(alpha) * X.norm(order)))
assert dif == 0
# ord=1
M = Matrix(3, 3, [1, 3, 0, -2, -1, 0, 3, 9, 6])
assert M.norm(1) == 13
def test_condition_number():
x = Symbol('x', real=True)
A = eye(3)
A[0, 0] = 10
A[2, 2] = S(1)/10
assert A.condition_number() == 100
A[1, 1] = x
assert A.condition_number() == Max(10, Abs(x)) / Min(S(1)/10, Abs(x))
M = Matrix([[cos(x), sin(x)], [-sin(x), cos(x)]])
Mc = M.condition_number()
assert all(Float(1.).epsilon_eq(Mc.subs(x, val).evalf()) for val in
[Rational(1, 5), Rational(1, 2), Rational(1, 10), pi/2, pi, 7*pi/4 ])
#issue 10782
assert Matrix([]).condition_number() == 0
def test_equality():
A = Matrix(((1, 2, 3), (4, 5, 6), (7, 8, 9)))
B = Matrix(((9, 8, 7), (6, 5, 4), (3, 2, 1)))
assert A == A[:, :]
assert not A != A[:, :]
assert not A == B
assert A != B
assert A != 10
assert not A == 10
# A SparseMatrix can be equal to a Matrix
C = SparseMatrix(((1, 0, 0), (0, 1, 0), (0, 0, 1)))
D = Matrix(((1, 0, 0), (0, 1, 0), (0, 0, 1)))
assert C == D
assert not C != D
def test_col_join():
assert eye(3).col_join(Matrix([[7, 7, 7]])) == \
Matrix([[1, 0, 0],
[0, 1, 0],
[0, 0, 1],
[7, 7, 7]])
def test_row_insert():
r4 = Matrix([[4, 4, 4]])
for i in range(-4, 5):
l = [1, 0, 0]
l.insert(i, 4)
assert flatten(eye(3).row_insert(i, r4).col(0).tolist()) == l
def test_col_insert():
c4 = Matrix([4, 4, 4])
for i in range(-4, 5):
l = [0, 0, 0]
l.insert(i, 4)
assert flatten(zeros(3).col_insert(i, c4).row(0).tolist()) == l
def test_normalized():
assert Matrix([3, 4]).normalized() == \
Matrix([Rational(3, 5), Rational(4, 5)])
# Zero vector trivial cases
assert Matrix([0, 0, 0]).normalized() == Matrix([0, 0, 0])
# Machine precision error truncation trivial cases
m = Matrix([0,0,1.e-100])
assert m.normalized(
iszerofunc=lambda x: x.evalf(n=10, chop=True).is_zero
) == Matrix([0, 0, 0])
def test_print_nonzero():
assert capture(lambda: eye(3).print_nonzero()) == \
'[X ]\n[ X ]\n[ X]\n'
assert capture(lambda: eye(3).print_nonzero('.')) == \
'[. ]\n[ . ]\n[ .]\n'
def test_zeros_eye():
assert Matrix.eye(3) == eye(3)
assert Matrix.zeros(3) == zeros(3)
assert ones(3, 4) == Matrix(3, 4, [1]*12)
i = Matrix([[1, 0], [0, 1]])
z = Matrix([[0, 0], [0, 0]])
for cls in classes:
m = cls.eye(2)
assert i == m # but m == i will fail if m is immutable
assert i == eye(2, cls=cls)
assert type(m) == cls
m = cls.zeros(2)
assert z == m
assert z == zeros(2, cls=cls)
assert type(m) == cls
def test_is_zero():
assert Matrix().is_zero
assert Matrix([[0, 0], [0, 0]]).is_zero
assert zeros(3, 4).is_zero
assert not eye(3).is_zero
assert Matrix([[x, 0], [0, 0]]).is_zero == None
assert SparseMatrix([[x, 0], [0, 0]]).is_zero == None
assert ImmutableMatrix([[x, 0], [0, 0]]).is_zero == None
assert ImmutableSparseMatrix([[x, 0], [0, 0]]).is_zero == None
assert Matrix([[x, 1], [0, 0]]).is_zero == False
a = Symbol('a', nonzero=True)
assert Matrix([[a, 0], [0, 0]]).is_zero == False
def test_rotation_matrices():
# This tests the rotation matrices by rotating about an axis and back.
theta = pi/3
r3_plus = rot_axis3(theta)
r3_minus = rot_axis3(-theta)
r2_plus = rot_axis2(theta)
r2_minus = rot_axis2(-theta)
r1_plus = rot_axis1(theta)
r1_minus = rot_axis1(-theta)
assert r3_minus*r3_plus*eye(3) == eye(3)
assert r2_minus*r2_plus*eye(3) == eye(3)
assert r1_minus*r1_plus*eye(3) == eye(3)
# Check the correctness of the trace of the rotation matrix
assert r1_plus.trace() == 1 + 2*cos(theta)
assert r2_plus.trace() == 1 + 2*cos(theta)
assert r3_plus.trace() == 1 + 2*cos(theta)
# Check that a rotation with zero angle doesn't change anything.
assert rot_axis1(0) == eye(3)
assert rot_axis2(0) == eye(3)
assert rot_axis3(0) == eye(3)
def test_DeferredVector():
assert str(DeferredVector("vector")[4]) == "vector[4]"
assert sympify(DeferredVector("d")) == DeferredVector("d")
def test_DeferredVector_not_iterable():
assert not iterable(DeferredVector('X'))
def test_DeferredVector_Matrix():
raises(TypeError, lambda: Matrix(DeferredVector("V")))
def test_GramSchmidt():
R = Rational
m1 = Matrix(1, 2, [1, 2])
m2 = Matrix(1, 2, [2, 3])
assert GramSchmidt([m1, m2]) == \
[Matrix(1, 2, [1, 2]), Matrix(1, 2, [R(2)/5, R(-1)/5])]
assert GramSchmidt([m1.T, m2.T]) == \
[Matrix(2, 1, [1, 2]), Matrix(2, 1, [R(2)/5, R(-1)/5])]
# from wikipedia
assert GramSchmidt([Matrix([3, 1]), Matrix([2, 2])], True) == [
Matrix([3*sqrt(10)/10, sqrt(10)/10]),
Matrix([-sqrt(10)/10, 3*sqrt(10)/10])]
def test_casoratian():
assert casoratian([1, 2, 3, 4], 1) == 0
assert casoratian([1, 2, 3, 4], 1, zero=False) == 0
def test_zero_dimension_multiply():
assert (Matrix()*zeros(0, 3)).shape == (0, 3)
assert zeros(3, 0)*zeros(0, 3) == zeros(3, 3)
assert zeros(0, 3)*zeros(3, 0) == Matrix()
def test_slice_issue_2884():
m = Matrix(2, 2, range(4))
assert m[1, :] == Matrix([[2, 3]])
assert m[-1, :] == Matrix([[2, 3]])
assert m[:, 1] == Matrix([[1, 3]]).T
assert m[:, -1] == Matrix([[1, 3]]).T
raises(IndexError, lambda: m[2, :])
raises(IndexError, lambda: m[2, 2])
def test_slice_issue_3401():
assert zeros(0, 3)[:, -1].shape == (0, 1)
assert zeros(3, 0)[0, :] == Matrix(1, 0, [])
def test_copyin():
s = zeros(3, 3)
s[3] = 1
assert s[:, 0] == Matrix([0, 1, 0])
assert s[3] == 1
assert s[3: 4] == [1]
s[1, 1] = 42
assert s[1, 1] == 42
assert s[1, 1:] == Matrix([[42, 0]])
s[1, 1:] = Matrix([[5, 6]])
assert s[1, :] == Matrix([[1, 5, 6]])
s[1, 1:] = [[42, 43]]
assert s[1, :] == Matrix([[1, 42, 43]])
s[0, 0] = 17
assert s[:, :1] == Matrix([17, 1, 0])
s[0, 0] = [1, 1, 1]
assert s[:, 0] == Matrix([1, 1, 1])
s[0, 0] = Matrix([1, 1, 1])
assert s[:, 0] == Matrix([1, 1, 1])
s[0, 0] = SparseMatrix([1, 1, 1])
assert s[:, 0] == Matrix([1, 1, 1])
def test_invertible_check():
# sometimes a singular matrix will have a pivot vector shorter than
# the number of rows in a matrix...
assert Matrix([[1, 2], [1, 2]]).rref() == (Matrix([[1, 2], [0, 0]]), (0,))
raises(ValueError, lambda: Matrix([[1, 2], [1, 2]]).inv())
m = Matrix([
[-1, -1, 0],
[ x, 1, 1],
[ 1, x, -1],
])
assert len(m.rref()[1]) != m.rows
# in addition, unless simplify=True in the call to rref, the identity
# matrix will be returned even though m is not invertible
assert m.rref()[0] != eye(3)
assert m.rref(simplify=signsimp)[0] != eye(3)
raises(ValueError, lambda: m.inv(method="ADJ"))
raises(ValueError, lambda: m.inv(method="GE"))
raises(ValueError, lambda: m.inv(method="LU"))
@XFAIL
def test_issue_3959():
x, y = symbols('x, y')
e = x*y
assert e.subs(x, Matrix([3, 5, 3])) == Matrix([3, 5, 3])*y
def test_issue_5964():
assert str(Matrix([[1, 2], [3, 4]])) == 'Matrix([[1, 2], [3, 4]])'
def test_issue_7604():
x, y = symbols(u"x y")
assert sstr(Matrix([[x, 2*y], [y**2, x + 3]])) == \
'Matrix([\n[ x, 2*y],\n[y**2, x + 3]])'
def test_is_Identity():
assert eye(3).is_Identity
assert eye(3).as_immutable().is_Identity
assert not zeros(3).is_Identity
assert not ones(3).is_Identity
# issue 6242
assert not Matrix([[1, 0, 0]]).is_Identity
# issue 8854
assert SparseMatrix(3,3, {(0,0):1, (1,1):1, (2,2):1}).is_Identity
assert not SparseMatrix(2,3, range(6)).is_Identity
assert not SparseMatrix(3,3, {(0,0):1, (1,1):1}).is_Identity
assert not SparseMatrix(3,3, {(0,0):1, (1,1):1, (2,2):1, (0,1):2, (0,2):3}).is_Identity
def test_dot():
assert ones(1, 3).dot(ones(3, 1)) == 3
assert ones(1, 3).dot([1, 1, 1]) == 3
assert Matrix([1, 2, 3]).dot(Matrix([1, 2, 3])) == 14
assert Matrix([1, 2, 3*I]).dot(Matrix([I, 2, 3*I])) == -5 + I
assert Matrix([1, 2, 3*I]).dot(Matrix([I, 2, 3*I]), hermitian=False) == -5 + I
assert Matrix([1, 2, 3*I]).dot(Matrix([I, 2, 3*I]), hermitian=True) == 13 + I
assert Matrix([1, 2, 3*I]).dot(Matrix([I, 2, 3*I]), hermitian=True, conjugate_convention="physics") == 13 - I
assert Matrix([1, 2, 3*I]).dot(Matrix([4, 5*I, 6]), hermitian=True, conjugate_convention="right") == 4 + 8*I
assert Matrix([1, 2, 3*I]).dot(Matrix([4, 5*I, 6]), hermitian=True, conjugate_convention="left") == 4 - 8*I
assert Matrix([I, 2*I]).dot(Matrix([I, 2*I]), hermitian=False, conjugate_convention="left") == -5
assert Matrix([I, 2*I]).dot(Matrix([I, 2*I]), conjugate_convention="left") == 5
def test_dual():
B_x, B_y, B_z, E_x, E_y, E_z = symbols(
'B_x B_y B_z E_x E_y E_z', real=True)
F = Matrix((
( 0, E_x, E_y, E_z),
(-E_x, 0, B_z, -B_y),
(-E_y, -B_z, 0, B_x),
(-E_z, B_y, -B_x, 0)
))
Fd = Matrix((
( 0, -B_x, -B_y, -B_z),
(B_x, 0, E_z, -E_y),
(B_y, -E_z, 0, E_x),
(B_z, E_y, -E_x, 0)
))
assert F.dual().equals(Fd)
assert eye(3).dual().equals(zeros(3))
assert F.dual().dual().equals(-F)
def test_anti_symmetric():
assert Matrix([1, 2]).is_anti_symmetric() is False
m = Matrix(3, 3, [0, x**2 + 2*x + 1, y, -(x + 1)**2, 0, x*y, -y, -x*y, 0])
assert m.is_anti_symmetric() is True
assert m.is_anti_symmetric(simplify=False) is False
assert m.is_anti_symmetric(simplify=lambda x: x) is False
# tweak to fail
m[2, 1] = -m[2, 1]
assert m.is_anti_symmetric() is False
# untweak
m[2, 1] = -m[2, 1]
m = m.expand()
assert m.is_anti_symmetric(simplify=False) is True
m[0, 0] = 1
assert m.is_anti_symmetric() is False
def test_normalize_sort_diogonalization():
A = Matrix(((1, 2), (2, 1)))
P, Q = A.diagonalize(normalize=True)
assert P*P.T == P.T*P == eye(P.cols)
P, Q = A.diagonalize(normalize=True, sort=True)
assert P*P.T == P.T*P == eye(P.cols)
assert P*Q*P.inv() == A
def test_issue_5321():
raises(ValueError, lambda: Matrix([[1, 2, 3], Matrix(0, 1, [])]))
def test_issue_5320():
assert Matrix.hstack(eye(2), 2*eye(2)) == Matrix([
[1, 0, 2, 0],
[0, 1, 0, 2]
])
assert Matrix.vstack(eye(2), 2*eye(2)) == Matrix([
[1, 0],
[0, 1],
[2, 0],
[0, 2]
])
cls = SparseMatrix
assert cls.hstack(cls(eye(2)), cls(2*eye(2))) == Matrix([
[1, 0, 2, 0],
[0, 1, 0, 2]
])
def test_issue_11944():
A = Matrix([[1]])
AIm = sympify(A)
assert Matrix.hstack(AIm, A) == Matrix([[1, 1]])
assert Matrix.vstack(AIm, A) == Matrix([[1], [1]])
def test_cross():
a = [1, 2, 3]
b = [3, 4, 5]
col = Matrix([-2, 4, -2])
row = col.T
def test(M, ans):
assert ans == M
assert type(M) == cls
for cls in classes:
A = cls(a)
B = cls(b)
test(A.cross(B), col)
test(A.cross(B.T), col)
test(A.T.cross(B.T), row)
test(A.T.cross(B), row)
raises(ShapeError, lambda:
Matrix(1, 2, [1, 1]).cross(Matrix(1, 2, [1, 1])))
def test_hash():
for cls in classes[-2:]:
s = {cls.eye(1), cls.eye(1)}
assert len(s) == 1 and s.pop() == cls.eye(1)
# issue 3979
for cls in classes[:2]:
assert not isinstance(cls.eye(1), Hashable)
@XFAIL
def test_issue_3979():
# when this passes, delete this and change the [1:2]
# to [:2] in the test_hash above for issue 3979
cls = classes[0]
raises(AttributeError, lambda: hash(cls.eye(1)))
def test_adjoint():
dat = [[0, I], [1, 0]]
ans = Matrix([[0, 1], [-I, 0]])
for cls in classes:
assert ans == cls(dat).adjoint()
def test_simplify_immutable():
from sympy import simplify, sin, cos
assert simplify(ImmutableMatrix([[sin(x)**2 + cos(x)**2]])) == \
ImmutableMatrix([[1]])
def test_rank():
from sympy.abc import x
m = Matrix([[1, 2], [x, 1 - 1/x]])
assert m.rank() == 2
n = Matrix(3, 3, range(1, 10))
assert n.rank() == 2
p = zeros(3)
assert p.rank() == 0
def test_issue_11434():
ax, ay, bx, by, cx, cy, dx, dy, ex, ey, t0, t1 = \
symbols('a_x a_y b_x b_y c_x c_y d_x d_y e_x e_y t_0 t_1')
M = Matrix([[ax, ay, ax*t0, ay*t0, 0],
[bx, by, bx*t0, by*t0, 0],
[cx, cy, cx*t0, cy*t0, 1],
[dx, dy, dx*t0, dy*t0, 1],
[ex, ey, 2*ex*t1 - ex*t0, 2*ey*t1 - ey*t0, 0]])
assert M.rank() == 4
def test_rank_regression_from_so():
# see:
# https://stackoverflow.com/questions/19072700/why-does-sympy-give-me-the-wrong-answer-when-i-row-reduce-a-symbolic-matrix
nu, lamb = symbols('nu, lambda')
A = Matrix([[-3*nu, 1, 0, 0],
[ 3*nu, -2*nu - 1, 2, 0],
[ 0, 2*nu, (-1*nu) - lamb - 2, 3],
[ 0, 0, nu + lamb, -3]])
expected_reduced = Matrix([[1, 0, 0, 1/(nu**2*(-lamb - nu))],
[0, 1, 0, 3/(nu*(-lamb - nu))],
[0, 0, 1, 3/(-lamb - nu)],
[0, 0, 0, 0]])
expected_pivots = (0, 1, 2)
reduced, pivots = A.rref()
assert simplify(expected_reduced - reduced) == zeros(*A.shape)
assert pivots == expected_pivots
def test_replace():
from sympy import symbols, Function, Matrix
F, G = symbols('F, G', cls=Function)
K = Matrix(2, 2, lambda i, j: G(i+j))
M = Matrix(2, 2, lambda i, j: F(i+j))
N = M.replace(F, G)
assert N == K
def test_replace_map():
from sympy import symbols, Function, Matrix
F, G = symbols('F, G', cls=Function)
K = Matrix(2, 2, [(G(0), {F(0): G(0)}), (G(1), {F(1): G(1)}), (G(1), {F(1)\
: G(1)}), (G(2), {F(2): G(2)})])
M = Matrix(2, 2, lambda i, j: F(i+j))
N = M.replace(F, G, True)
assert N == K
def test_atoms():
m = Matrix([[1, 2], [x, 1 - 1/x]])
assert m.atoms() == {S(1),S(2),S(-1), x}
assert m.atoms(Symbol) == {x}
@slow
def test_pinv():
# Pseudoinverse of an invertible matrix is the inverse.
A1 = Matrix([[a, b], [c, d]])
assert simplify(A1.pinv()) == simplify(A1.inv())
# Test the four properties of the pseudoinverse for various matrices.
As = [Matrix([[13, 104], [2212, 3], [-3, 5]]),
Matrix([[1, 7, 9], [11, 17, 19]]),
Matrix([a, b])]
for A in As:
A_pinv = A.pinv()
AAp = A * A_pinv
ApA = A_pinv * A
assert simplify(AAp * A) == A
assert simplify(ApA * A_pinv) == A_pinv
assert AAp.H == AAp
assert ApA.H == ApA
def test_pinv_solve():
# Fully determined system (unique result, identical to other solvers).
A = Matrix([[1, 5], [7, 9]])
B = Matrix([12, 13])
assert A.pinv_solve(B) == A.cholesky_solve(B)
assert A.pinv_solve(B) == A.LDLsolve(B)
assert A.pinv_solve(B) == Matrix([sympify('-43/26'), sympify('71/26')])
assert A * A.pinv() * B == B
# Fully determined, with two-dimensional B matrix.
B = Matrix([[12, 13, 14], [15, 16, 17]])
assert A.pinv_solve(B) == A.cholesky_solve(B)
assert A.pinv_solve(B) == A.LDLsolve(B)
assert A.pinv_solve(B) == Matrix([[-33, -37, -41], [69, 75, 81]]) / 26
assert A * A.pinv() * B == B
# Underdetermined system (infinite results).
A = Matrix([[1, 0, 1], [0, 1, 1]])
B = Matrix([5, 7])
solution = A.pinv_solve(B)
w = {}
for s in solution.atoms(Symbol):
# Extract dummy symbols used in the solution.
w[s.name] = s
assert solution == Matrix([[w['w0_0']/3 + w['w1_0']/3 - w['w2_0']/3 + 1],
[w['w0_0']/3 + w['w1_0']/3 - w['w2_0']/3 + 3],
[-w['w0_0']/3 - w['w1_0']/3 + w['w2_0']/3 + 4]])
assert A * A.pinv() * B == B
# Overdetermined system (least squares results).
A = Matrix([[1, 0], [0, 0], [0, 1]])
B = Matrix([3, 2, 1])
assert A.pinv_solve(B) == Matrix([3, 1])
# Proof the solution is not exact.
assert A * A.pinv() * B != B
def test_pinv_rank_deficient():
# Test the four properties of the pseudoinverse for various matrices.
As = [Matrix([[1, 1, 1], [2, 2, 2]]),
Matrix([[1, 0], [0, 0]]),
Matrix([[1, 2], [2, 4], [3, 6]])]
for A in As:
A_pinv = A.pinv()
AAp = A * A_pinv
ApA = A_pinv * A
assert simplify(AAp * A) == A
assert simplify(ApA * A_pinv) == A_pinv
assert AAp.H == AAp
assert ApA.H == ApA
# Test solving with rank-deficient matrices.
A = Matrix([[1, 0], [0, 0]])
# Exact, non-unique solution.
B = Matrix([3, 0])
solution = A.pinv_solve(B)
w1 = solution.atoms(Symbol).pop()
assert w1.name == 'w1_0'
assert solution == Matrix([3, w1])
assert A * A.pinv() * B == B
# Least squares, non-unique solution.
B = Matrix([3, 1])
solution = A.pinv_solve(B)
w1 = solution.atoms(Symbol).pop()
assert w1.name == 'w1_0'
assert solution == Matrix([3, w1])
assert A * A.pinv() * B != B
@XFAIL
def test_pinv_rank_deficient_when_diagonalization_fails():
# Test the four properties of the pseudoinverse for matrices when
# diagonalization of A.H*A fails.'
As = [Matrix([
[61, 89, 55, 20, 71, 0],
[62, 96, 85, 85, 16, 0],
[69, 56, 17, 4, 54, 0],
[10, 54, 91, 41, 71, 0],
[ 7, 30, 10, 48, 90, 0],
[0,0,0,0,0,0]])]
for A in As:
A_pinv = A.pinv()
AAp = A * A_pinv
ApA = A_pinv * A
assert simplify(AAp * A) == A
assert simplify(ApA * A_pinv) == A_pinv
assert AAp.H == AAp
assert ApA.H == ApA
def test_gauss_jordan_solve():
# Square, full rank, unique solution
A = Matrix([[1, 2, 3], [4, 5, 6], [7, 8, 10]])
b = Matrix([3, 6, 9])
sol, params = A.gauss_jordan_solve(b)
assert sol == Matrix([[-1], [2], [0]])
assert params == Matrix(0, 1, [])
# Square, reduced rank, parametrized solution
A = Matrix([[1, 2, 3], [4, 5, 6], [7, 8, 9]])
b = Matrix([3, 6, 9])
sol, params, freevar = A.gauss_jordan_solve(b, freevar=True)
w = {}
for s in sol.atoms(Symbol):
# Extract dummy symbols used in the solution.
w[s.name] = s
assert sol == Matrix([[w['tau0'] - 1], [-2*w['tau0'] + 2], [w['tau0']]])
assert params == Matrix([[w['tau0']]])
assert freevar == [2]
# Square, reduced rank, parametrized solution
A = Matrix([[1, 2, 3], [2, 4, 6], [3, 6, 9]])
b = Matrix([0, 0, 0])
sol, params = A.gauss_jordan_solve(b)
w = {}
for s in sol.atoms(Symbol):
w[s.name] = s
assert sol == Matrix([[-2*w['tau0'] - 3*w['tau1']],
[w['tau0']], [w['tau1']]])
assert params == Matrix([[w['tau0']], [w['tau1']]])
# Square, reduced rank, parametrized solution
A = Matrix([[0, 0, 0], [0, 0, 0], [0, 0, 0]])
b = Matrix([0, 0, 0])
sol, params = A.gauss_jordan_solve(b)
w = {}
for s in sol.atoms(Symbol):
w[s.name] = s
assert sol == Matrix([[w['tau0']], [w['tau1']], [w['tau2']]])
assert params == Matrix([[w['tau0']], [w['tau1']], [w['tau2']]])
# Square, reduced rank, no solution
A = Matrix([[1, 2, 3], [2, 4, 6], [3, 6, 9]])
b = Matrix([0, 0, 1])
raises(ValueError, lambda: A.gauss_jordan_solve(b))
# Rectangular, tall, full rank, unique solution
A = Matrix([[1, 5, 3], [2, 1, 6], [1, 7, 9], [1, 4, 3]])
b = Matrix([0, 0, 1, 0])
sol, params = A.gauss_jordan_solve(b)
assert sol == Matrix([[-S(1)/2], [0], [S(1)/6]])
assert params == Matrix(0, 1, [])
# Rectangular, tall, full rank, no solution
A = Matrix([[1, 5, 3], [2, 1, 6], [1, 7, 9], [1, 4, 3]])
b = Matrix([0, 0, 0, 1])
raises(ValueError, lambda: A.gauss_jordan_solve(b))
# Rectangular, tall, reduced rank, parametrized solution
A = Matrix([[1, 5, 3], [2, 10, 6], [3, 15, 9], [1, 4, 3]])
b = Matrix([0, 0, 0, 1])
sol, params = A.gauss_jordan_solve(b)
w = {}
for s in sol.atoms(Symbol):
w[s.name] = s
assert sol == Matrix([[-3*w['tau0'] + 5], [-1], [w['tau0']]])
assert params == Matrix([[w['tau0']]])
# Rectangular, tall, reduced rank, no solution
A = Matrix([[1, 5, 3], [2, 10, 6], [3, 15, 9], [1, 4, 3]])
b = Matrix([0, 0, 1, 1])
raises(ValueError, lambda: A.gauss_jordan_solve(b))
# Rectangular, wide, full rank, parametrized solution
A = Matrix([[1, 2, 3, 4], [5, 6, 7, 8], [9, 10, 1, 12]])
b = Matrix([1, 1, 1])
sol, params = A.gauss_jordan_solve(b)
w = {}
for s in sol.atoms(Symbol):
w[s.name] = s
assert sol == Matrix([[2*w['tau0'] - 1], [-3*w['tau0'] + 1], [0],
[w['tau0']]])
assert params == Matrix([[w['tau0']]])
# Rectangular, wide, reduced rank, parametrized solution
A = Matrix([[1, 2, 3, 4], [5, 6, 7, 8], [2, 4, 6, 8]])
b = Matrix([0, 1, 0])
sol, params = A.gauss_jordan_solve(b)
w = {}
for s in sol.atoms(Symbol):
w[s.name] = s
assert sol == Matrix([[w['tau0'] + 2*w['tau1'] + 1/S(2)],
[-2*w['tau0'] - 3*w['tau1'] - 1/S(4)],
[w['tau0']], [w['tau1']]])
assert params == Matrix([[w['tau0']], [w['tau1']]])
# watch out for clashing symbols
x0, x1, x2, _x0 = symbols('_tau0 _tau1 _tau2 tau1')
M = Matrix([[0, 1, 0, 0, 0, 0], [0, 0, 0, 1, 0, _x0]])
A = M[:, :-1]
b = M[:, -1:]
sol, params = A.gauss_jordan_solve(b)
assert params == Matrix(3, 1, [x0, x1, x2])
assert sol == Matrix(5, 1, [x1, 0, x0, _x0, x2])
# Rectangular, wide, reduced rank, no solution
A = Matrix([[1, 2, 3, 4], [5, 6, 7, 8], [2, 4, 6, 8]])
b = Matrix([1, 1, 1])
raises(ValueError, lambda: A.gauss_jordan_solve(b))
def test_solve():
A = Matrix([[1,2], [2,4]])
b = Matrix([[3], [4]])
raises(ValueError, lambda: A.solve(b)) #no solution
b = Matrix([[ 4], [8]])
raises(ValueError, lambda: A.solve(b)) #infinite solution
def test_issue_7201():
assert ones(0, 1) + ones(0, 1) == Matrix(0, 1, [])
assert ones(1, 0) + ones(1, 0) == Matrix(1, 0, [])
def test_free_symbols():
for M in ImmutableMatrix, ImmutableSparseMatrix, Matrix, SparseMatrix:
assert M([[x], [0]]).free_symbols == {x}
def test_from_ndarray():
"""See issue 7465."""
try:
from numpy import array
except ImportError:
skip('NumPy must be available to test creating matrices from ndarrays')
assert Matrix(array([1, 2, 3])) == Matrix([1, 2, 3])
assert Matrix(array([[1, 2, 3]])) == Matrix([[1, 2, 3]])
assert Matrix(array([[1, 2, 3], [4, 5, 6]])) == \
Matrix([[1, 2, 3], [4, 5, 6]])
assert Matrix(array([x, y, z])) == Matrix([x, y, z])
raises(NotImplementedError, lambda: Matrix(array([[
[1, 2], [3, 4]], [[5, 6], [7, 8]]])))
def test_hermitian():
a = Matrix([[1, I], [-I, 1]])
assert a.is_hermitian
a[0, 0] = 2*I
assert a.is_hermitian is False
a[0, 0] = x
assert a.is_hermitian is None
a[0, 1] = a[1, 0]*I
assert a.is_hermitian is False
def test_doit():
a = Matrix([[Add(x,x, evaluate=False)]])
assert a[0] != 2*x
assert a.doit() == Matrix([[2*x]])
def test_issue_9457_9467_9876():
# for row_del(index)
M = Matrix([[1, 2, 3], [2, 3, 4], [3, 4, 5]])
M.row_del(1)
assert M == Matrix([[1, 2, 3], [3, 4, 5]])
N = Matrix([[1, 2, 3], [2, 3, 4], [3, 4, 5]])
N.row_del(-2)
assert N == Matrix([[1, 2, 3], [3, 4, 5]])
O = Matrix([[1, 2, 3], [5, 6, 7], [9, 10, 11]])
O.row_del(-1)
assert O == Matrix([[1, 2, 3], [5, 6, 7]])
P = Matrix([[1, 2, 3], [2, 3, 4], [3, 4, 5]])
raises(IndexError, lambda: P.row_del(10))
Q = Matrix([[1, 2, 3], [2, 3, 4], [3, 4, 5]])
raises(IndexError, lambda: Q.row_del(-10))
# for col_del(index)
M = Matrix([[1, 2, 3], [2, 3, 4], [3, 4, 5]])
M.col_del(1)
assert M == Matrix([[1, 3], [2, 4], [3, 5]])
N = Matrix([[1, 2, 3], [2, 3, 4], [3, 4, 5]])
N.col_del(-2)
assert N == Matrix([[1, 3], [2, 4], [3, 5]])
P = Matrix([[1, 2, 3], [2, 3, 4], [3, 4, 5]])
raises(IndexError, lambda: P.col_del(10))
Q = Matrix([[1, 2, 3], [2, 3, 4], [3, 4, 5]])
raises(IndexError, lambda: Q.col_del(-10))
def test_issue_9422():
x, y = symbols('x y', commutative=False)
a, b = symbols('a b')
M = eye(2)
M1 = Matrix(2, 2, [x, y, y, z])
assert y*x*M != x*y*M
assert b*a*M == a*b*M
assert x*M1 != M1*x
assert a*M1 == M1*a
assert y*x*M == Matrix([[y*x, 0], [0, y*x]])
def test_issue_10770():
M = Matrix([])
a = ['col_insert', 'row_join'], Matrix([9, 6, 3])
b = ['row_insert', 'col_join'], a[1].T
c = ['row_insert', 'col_insert'], Matrix([[1, 2], [3, 4]])
for ops, m in (a, b, c):
for op in ops:
f = getattr(M, op)
new = f(m) if 'join' in op else f(42, m)
assert new == m and id(new) != id(m)
def test_issue_10658():
A = Matrix([[1, 2, 3], [4, 5, 6], [7, 8, 9]])
assert A.extract([0, 1, 2], [True, True, False]) == \
Matrix([[1, 2], [4, 5], [7, 8]])
assert A.extract([0, 1, 2], [True, False, False]) == Matrix([[1], [4], [7]])
assert A.extract([True, False, False], [0, 1, 2]) == Matrix([[1, 2, 3]])
assert A.extract([True, False, True], [0, 1, 2]) == \
Matrix([[1, 2, 3], [7, 8, 9]])
assert A.extract([0, 1, 2], [False, False, False]) == Matrix(3, 0, [])
assert A.extract([False, False, False], [0, 1, 2]) == Matrix(0, 3, [])
assert A.extract([True, False, True], [False, True, False]) == \
Matrix([[2], [8]])
def test_opportunistic_simplification():
# this test relates to issue #10718, #9480, #11434
# issue #9480
m = Matrix([[-5 + 5*sqrt(2), -5], [-5*sqrt(2)/2 + 5, -5*sqrt(2)/2]])
assert m.rank() == 1
# issue #10781
m = Matrix([[3+3*sqrt(3)*I, -9],[4,-3+3*sqrt(3)*I]])
assert simplify(m.rref()[0] - Matrix([[1, -9/(3 + 3*sqrt(3)*I)], [0, 0]])) == zeros(2, 2)
# issue #11434
ax,ay,bx,by,cx,cy,dx,dy,ex,ey,t0,t1 = symbols('a_x a_y b_x b_y c_x c_y d_x d_y e_x e_y t_0 t_1')
m = Matrix([[ax,ay,ax*t0,ay*t0,0],[bx,by,bx*t0,by*t0,0],[cx,cy,cx*t0,cy*t0,1],[dx,dy,dx*t0,dy*t0,1],[ex,ey,2*ex*t1-ex*t0,2*ey*t1-ey*t0,0]])
assert m.rank() == 4
def test_partial_pivoting():
# example from https://en.wikipedia.org/wiki/Pivot_element
# partial pivoting with back subsitution gives a perfect result
# naive pivoting give an error ~1e-13, so anything better than
# 1e-15 is good
mm=Matrix([[0.003 ,59.14, 59.17],[ 5.291, -6.13,46.78]])
assert (mm.rref()[0] - Matrix([[1.0, 0, 10.0], [ 0, 1.0, 1.0]])).norm() < 1e-15
# issue #11549
m_mixed = Matrix([[6e-17, 1.0, 4],[ -1.0, 0, 8],[ 0, 0, 1]])
m_float = Matrix([[6e-17, 1.0, 4.],[ -1.0, 0., 8.],[ 0., 0., 1.]])
m_inv = Matrix([[ 0, -1.0, 8.0],[1.0, 6.0e-17, -4.0],[ 0, 0, 1]])
# this example is numerically unstable and involves a matrix with a norm >= 8,
# this comparing the difference of the results with 1e-15 is numerically sound.
assert (m_mixed.inv() - m_inv).norm() < 1e-15
assert (m_float.inv() - m_inv).norm() < 1e-15
def test_iszero_substitution():
""" When doing numerical computations, all elements that pass
the iszerofunc test should be set to numerically zero if they
aren't already. """
# Matrix from issue #9060
m = Matrix([[0.9, -0.1, -0.2, 0],[-0.8, 0.9, -0.4, 0],[-0.1, -0.8, 0.6, 0]])
m_rref = m.rref(iszerofunc=lambda x: abs(x)<6e-15)[0]
m_correct = Matrix([[1.0, 0, -0.301369863013699, 0],[ 0, 1.0, -0.712328767123288, 0],[ 0, 0, 0, 0]])
m_diff = m_rref - m_correct
assert m_diff.norm() < 1e-15
# if a zero-substitution wasn't made, this entry will be -1.11022302462516e-16
assert m_rref[2,2] == 0
@slow
def test_issue_11238():
from sympy import Point
xx = 8*tan(13*pi/45)/(tan(13*pi/45) + sqrt(3))
yy = (-8*sqrt(3)*tan(13*pi/45)**2 + 24*tan(13*pi/45))/(-3 + tan(13*pi/45)**2)
p1 = Point(0, 0)
p2 = Point(1, -sqrt(3))
p0 = Point(xx,yy)
m1 = Matrix([p1 - simplify(p0), p2 - simplify(p0)])
m2 = Matrix([p1 - p0, p2 - p0])
m3 = Matrix([simplify(p1 - p0), simplify(p2 - p0)])
assert m1.rank(simplify=True) == 1
assert m2.rank(simplify=True) == 1
assert m3.rank(simplify=True) == 1
def test_as_real_imag():
m1 = Matrix(2,2,[1,2,3,4])
m2 = m1*S.ImaginaryUnit
m3 = m1 + m2
for kls in classes:
a,b = kls(m3).as_real_imag()
assert list(a) == list(m1)
assert list(b) == list(m1)
def test_deprecated():
# Maintain tests for deprecated functions. We must capture
# the deprecation warnings. When the deprecated functionality is
# removed, the corresponding tests should be removed.
m = Matrix(3, 3, [0, 1, 0, -4, 4, 0, -2, 1, 2])
P, Jcells = m.jordan_cells()
assert Jcells[1] == Matrix(1, 1, [2])
assert Jcells[0] == Matrix(2, 2, [2, 1, 0, 2])
with warns_deprecated_sympy():
assert Matrix([[1,2],[3,4]]).dot(Matrix([[1,3],[4,5]])) == [10, 19, 14, 28]
def test_issue_14489():
from sympy import Mod
A = Matrix([-1, 1, 2])
B = Matrix([10, 20, -15])
assert Mod(A, 3) == Matrix([2, 1, 2])
assert Mod(B, 4) == Matrix([2, 0, 1])
def test_issue_14517():
M = Matrix([
[ 0, 10*I, 10*I, 0],
[10*I, 0, 0, 10*I],
[10*I, 0, 5 + 2*I, 10*I],
[ 0, 10*I, 10*I, 5 + 2*I]])
ev = M.eigenvals()
# test one random eigenvalue, the computation is a little slow
test_ev = random.choice(list(ev.keys()))
assert (M - test_ev*eye(4)).det() == 0
def test_issue_14943():
# Test that __array__ accepts the optional dtype argument
try:
from numpy import array
except ImportError:
skip('NumPy must be available to test creating matrices from ndarrays')
M = Matrix([[1,2], [3,4]])
assert array(M, dtype=float).dtype.name == 'float64'
def test_issue_8240():
# Eigenvalues of large triangular matrices
n = 200
diagonal_variables = [Symbol('x%s' % i) for i in range(n)]
M = [[0 for i in range(n)] for j in range(n)]
for i in range(n):
M[i][i] = diagonal_variables[i]
M = Matrix(M)
eigenvals = M.eigenvals()
assert len(eigenvals) == n
for i in range(n):
assert eigenvals[diagonal_variables[i]] == 1
eigenvals = M.eigenvals(multiple=True)
assert set(eigenvals) == set(diagonal_variables)
# with multiplicity
M = Matrix([[x, 0, 0], [1, y, 0], [2, 3, x]])
eigenvals = M.eigenvals()
assert eigenvals == {x: 2, y: 1}
eigenvals = M.eigenvals(multiple=True)
assert len(eigenvals) == 3
assert eigenvals.count(x) == 2
assert eigenvals.count(y) == 1
def test_legacy_det():
# Minimal support for legacy keys for 'method' in det()
# Partially copied from test_determinant()
M = Matrix(( ( 3, -2, 0, 5),
(-2, 1, -2, 2),
( 0, -2, 5, 0),
( 5, 0, 3, 4) ))
assert M.det(method="bareis") == -289
assert M.det(method="det_lu") == -289
assert M.det(method="det_LU") == -289
M = Matrix(( (3, 2, 0, 0, 0),
(0, 3, 2, 0, 0),
(0, 0, 3, 2, 0),
(0, 0, 0, 3, 2),
(2, 0, 0, 0, 3) ))
assert M.det(method="bareis") == 275
assert M.det(method="det_lu") == 275
assert M.det(method="Bareis") == 275
M = Matrix(( (1, 0, 1, 2, 12),
(2, 0, 1, 1, 4),
(2, 1, 1, -1, 3),
(3, 2, -1, 1, 8),
(1, 1, 1, 0, 6) ))
assert M.det(method="bareis") == -55
assert M.det(method="det_lu") == -55
assert M.det(method="BAREISS") == -55
M = Matrix(( (-5, 2, 3, 4, 5),
( 1, -4, 3, 4, 5),
( 1, 2, -3, 4, 5),
( 1, 2, 3, -2, 5),
( 1, 2, 3, 4, -1) ))
assert M.det(method="bareis") == 11664
assert M.det(method="det_lu") == 11664
assert M.det(method="BERKOWITZ") == 11664
M = Matrix(( ( 2, 7, -1, 3, 2),
( 0, 0, 1, 0, 1),
(-2, 0, 7, 0, 2),
(-3, -2, 4, 5, 3),
( 1, 0, 0, 0, 1) ))
assert M.det(method="bareis") == 123
assert M.det(method="det_lu") == 123
assert M.det(method="LU") == 123
|
dc7bcd99538cfa47c299800b48bdd5062cab0346fdf00db405ecaf19d63de9fb
|
#!/usr/bin/env python
"""Grover's quantum search algorithm example."""
from sympy import pprint
from sympy.physics.quantum import qapply
from sympy.physics.quantum.qubit import IntQubit
from sympy.physics.quantum.grover import (OracleGate, superposition_basis,
WGate, grover_iteration)
def demo_vgate_app(v):
for i in range(2**v.nqubits):
print('qapply(v*IntQubit(%i, %r))' % (i, v.nqubits))
pprint(qapply(v*IntQubit(i, nqubits=v.nqubits)))
qapply(v*IntQubit(i, nqubits=v.nqubits))
def black_box(qubits):
return True if qubits == IntQubit(1, nqubits=qubits.nqubits) else False
def main():
print()
print('Demonstration of Grover\'s Algorithm')
print('The OracleGate or V Gate carries the unknown function f(x)')
print('> V|x> = ((-1)^f(x))|x> where f(x) = 1 when x = a (True in our case)')
print('> and 0 (False in our case) otherwise')
print()
nqubits = 2
print('nqubits = ', nqubits)
v = OracleGate(nqubits, black_box)
print('Oracle or v = OracleGate(%r, black_box)' % nqubits)
print()
psi = superposition_basis(nqubits)
print('psi:')
pprint(psi)
demo_vgate_app(v)
print('qapply(v*psi)')
pprint(qapply(v*psi))
print()
w = WGate(nqubits)
print('WGate or w = WGate(%r)' % nqubits)
print('On a 2 Qubit system like psi, 1 iteration is enough to yield |1>')
print('qapply(w*v*psi)')
pprint(qapply(w*v*psi))
print()
nqubits = 3
print('On a 3 Qubit system, it requires 2 iterations to achieve')
print('|1> with high enough probability')
psi = superposition_basis(nqubits)
print('psi:')
pprint(psi)
v = OracleGate(nqubits, black_box)
print('Oracle or v = OracleGate(%r, black_box)' % nqubits)
print()
print('iter1 = grover.grover_iteration(psi, v)')
iter1 = qapply(grover_iteration(psi, v))
pprint(iter1)
print()
print('iter2 = grover.grover_iteration(iter1, v)')
iter2 = qapply(grover_iteration(iter1, v))
pprint(iter2)
print()
if __name__ == "__main__":
main()
|
84f15dc404963a15d8822b6bbb666ad8a7c53bb3b0bfe1c8bf0f50088e3a4470
|
# -*- coding: utf-8 -*-
#
# SymPy documentation build configuration file, created by
# sphinx-quickstart.py on Sat Mar 22 19:34:32 2008.
#
# This file is execfile()d with the current directory set to its containing dir.
#
# The contents of this file are pickled, so don't put values in the namespace
# that aren't pickleable (module imports are okay, they're removed automatically).
#
# All configuration values have a default value; values that are commented out
# serve to show the default value.
import sys
import sympy
# If your extensions are in another directory, add it here.
sys.path = ['ext'] + sys.path
# General configuration
# ---------------------
# Add any Sphinx extension module names here, as strings. They can be extensions
# coming with Sphinx (named 'sphinx.addons.*') or your custom ones.
extensions = ['sphinx.ext.autodoc', 'sphinx.ext.viewcode',
'sphinx.ext.mathjax', 'numpydoc', 'sympylive',
'sphinx.ext.graphviz', 'matplotlib.sphinxext.plot_directive']
# Use this to use pngmath instead
#extensions = ['sphinx.ext.autodoc', 'sphinx.ext.viewcode', 'sphinx.ext.pngmath', ]
# To stop docstrings inheritance.
autodoc_inherit_docstrings = False
# MathJax file, which is free to use. See https://www.mathjax.org/#gettingstarted
# As explained in the link using latest.js will get the latest version even
# though it says 2.7.5.
mathjax_path = 'https://cdnjs.cloudflare.com/ajax/libs/mathjax/2.7.5/latest.js?config=TeX-AMS_HTML-full'
# Add any paths that contain templates here, relative to this directory.
templates_path = ['_templates']
# The suffix of source filenames.
source_suffix = '.rst'
# The master toctree document.
master_doc = 'index'
suppress_warnings = ['ref.citation', 'ref.footnote']
# General substitutions.
project = 'SymPy'
copyright = '2018 SymPy Development Team'
# The default replacements for |version| and |release|, also used in various
# other places throughout the built documents.
#
# The short X.Y version.
version = sympy.__version__
# The full version, including alpha/beta/rc tags.
release = version
# There are two options for replacing |today|: either, you set today to some
# non-false value, then it is used:
#today = ''
# Else, today_fmt is used as the format for a strftime call.
today_fmt = '%B %d, %Y'
# List of documents that shouldn't be included in the build.
#unused_docs = []
# If true, '()' will be appended to :func: etc. cross-reference text.
#add_function_parentheses = True
# If true, the current module name will be prepended to all description
# unit titles (such as .. function::).
#add_module_names = True
# If true, sectionauthor and moduleauthor directives will be shown in the
# output. They are ignored by default.
#show_authors = False
# The name of the Pygments (syntax highlighting) style to use.
pygments_style = 'sphinx'
# Don't show the source code hyperlinks when using matplotlib plot directive.
plot_html_show_source_link = False
# Options for HTML output
# -----------------------
# The style sheet to use for HTML and HTML Help pages. A file of that name
# must exist either in Sphinx' static/ path, or in one of the custom paths
# given in html_static_path.
html_style = 'default.css'
# Add any paths that contain custom static files (such as style sheets) here,
# relative to this directory. They are copied after the builtin static files,
# so a file named "default.css" will overwrite the builtin "default.css".
html_static_path = ['_static']
# If not '', a 'Last updated on:' timestamp is inserted at every page bottom,
# using the given strftime format.
html_last_updated_fmt = '%b %d, %Y'
html_theme = 'classic'
html_logo = '_static/sympylogo.png'
html_favicon = '../_build/logo/sympy-notailtext-favicon.ico'
# See http://www.sphinx-doc.org/en/master/theming.html#builtin-themes
# If true, SmartyPants will be used to convert quotes and dashes to
# typographically correct entities.
#html_use_smartypants = True
# Content template for the index page.
#html_index = ''
# Custom sidebar templates, maps document names to template names.
#html_sidebars = {}
# Additional templates that should be rendered to pages, maps page names to
# template names.
#html_additional_pages = {}
# If false, no module index is generated.
#html_use_modindex = True
html_domain_indices = ['py-modindex']
# If true, the reST sources are included in the HTML build as _sources/<name>.
#html_copy_source = True
# Output file base name for HTML help builder.
htmlhelp_basename = 'SymPydoc'
# Options for LaTeX output
# ------------------------
# The paper size ('letter' or 'a4').
#latex_paper_size = 'letter'
# The font size ('10pt', '11pt' or '12pt').
#latex_font_size = '10pt'
# Grouping the document tree into LaTeX files. List of tuples
# (source start file, target name, title, author, document class [howto/manual], toctree_only).
# toctree_only is set to True so that the start file document itself is not included in the
# output, only the documents referenced by it via TOC trees. The extra stuff in the master
# document is intended to show up in the HTML, but doesn't really belong in the LaTeX output.
latex_documents = [('index', 'sympy-%s.tex' % release, 'SymPy Documentation',
'SymPy Development Team', 'manual', True)]
# Additional stuff for the LaTeX preamble.
# Tweaked to work with XeTeX.
latex_elements = {
'babel': '',
'fontenc': r'''
\usepackage{bm}
\usepackage{amssymb}
\usepackage{fontspec}
\usepackage[english]{babel}
\defaultfontfeatures{Mapping=tex-text}
\setmainfont{DejaVu Serif}
\setsansfont{DejaVu Sans}
\setmonofont{DejaVu Sans Mono}
''',
'fontpkg': '',
'inputenc': '',
'utf8extra': '',
'preamble': r'''
% redefine \LaTeX to be usable in math mode
\expandafter\def\expandafter\LaTeX\expandafter{\expandafter\text\expandafter{\LaTeX}}
'''
}
# SymPy logo on title page
html_logo = '_static/sympylogo.png'
latex_logo = '_static/sympylogo_big.png'
# Documents to append as an appendix to all manuals.
#latex_appendices = []
# Show page numbers next to internal references
latex_show_pagerefs = True
# We use False otherwise the module index gets generated twice.
latex_use_modindex = False
default_role = 'math'
pngmath_divpng_args = ['-gamma 1.5', '-D 110']
# Note, this is ignored by the mathjax extension
# Any \newcommand should be defined in the file
pngmath_latex_preamble = '\\usepackage{amsmath}\n' \
'\\usepackage{bm}\n' \
'\\usepackage{amsfonts}\n' \
'\\usepackage{amssymb}\n' \
'\\setlength{\\parindent}{0pt}\n'
texinfo_documents = [
(master_doc, 'sympy', 'SymPy Documentation', 'SymPy Development Team',
'SymPy', 'Computer algebra system (CAS) in Python', 'Programming', 1),
]
# Use svg for graphviz
graphviz_output_format = 'svg'
|
0c84ae534c53a876b5fd99af92fe70c8d72ef6b0df1f9fa16ecef3705b58079f
|
"""
Continuous Random Variables - Prebuilt variables
Contains
========
Arcsin
Benini
Beta
BetaPrime
Cauchy
Chi
ChiNoncentral
ChiSquared
Dagum
Erlang
Exponential
FDistribution
FisherZ
Frechet
Gamma
GammaInverse
Gumbel
Gompertz
Kumaraswamy
Laplace
Logistic
LogNormal
Maxwell
Nakagami
Normal
Pareto
QuadraticU
RaisedCosine
Rayleigh
ShiftedGompertz
StudentT
Trapezoidal
Triangular
Uniform
UniformSum
VonMises
Weibull
WignerSemicircle
"""
from __future__ import print_function, division
from sympy import (log, sqrt, pi, S, Dummy, Interval, sympify, gamma,
Piecewise, And, Eq, binomial, factorial, Sum, floor, Abs,
Lambda, Basic, lowergamma, erf, erfi, I, hyper, uppergamma,
sinh, Ne, expint)
from sympy import beta as beta_fn
from sympy import cos, sin, exp, besseli, besselj, besselk
from sympy.external import import_module
from sympy.matrices import MatrixBase
from sympy.stats.crv import (SingleContinuousPSpace, SingleContinuousDistribution,
ContinuousDistributionHandmade)
from sympy.stats.joint_rv import JointPSpace, CompoundDistribution
from sympy.stats.joint_rv_types import multivariate_rv
from sympy.stats.rv import _value_check, RandomSymbol
import random
oo = S.Infinity
__all__ = ['ContinuousRV',
'Arcsin',
'Benini',
'Beta',
'BetaPrime',
'Cauchy',
'Chi',
'ChiNoncentral',
'ChiSquared',
'Dagum',
'Erlang',
'Exponential',
'FDistribution',
'FisherZ',
'Frechet',
'Gamma',
'GammaInverse',
'Gompertz',
'Gumbel',
'Kumaraswamy',
'Laplace',
'Logistic',
'LogNormal',
'Maxwell',
'Nakagami',
'Normal',
'Pareto',
'QuadraticU',
'RaisedCosine',
'Rayleigh',
'StudentT',
'ShiftedGompertz',
'Trapezoidal',
'Triangular',
'Uniform',
'UniformSum',
'VonMises',
'Weibull',
'WignerSemicircle'
]
def ContinuousRV(symbol, density, set=Interval(-oo, oo)):
"""
Create a Continuous Random Variable given the following:
-- a symbol
-- a probability density function
-- set on which the pdf is valid (defaults to entire real line)
Returns a RandomSymbol.
Many common continuous random variable types are already implemented.
This function should be necessary only very rarely.
Examples
========
>>> from sympy import Symbol, sqrt, exp, pi
>>> from sympy.stats import ContinuousRV, P, E
>>> x = Symbol("x")
>>> pdf = sqrt(2)*exp(-x**2/2)/(2*sqrt(pi)) # Normal distribution
>>> X = ContinuousRV(x, pdf)
>>> E(X)
0
>>> P(X>0)
1/2
"""
pdf = Piecewise((density, set.as_relational(symbol)), (0, True))
pdf = Lambda(symbol, pdf)
dist = ContinuousDistributionHandmade(pdf, set)
return SingleContinuousPSpace(symbol, dist).value
def rv(symbol, cls, args):
args = list(map(sympify, args))
dist = cls(*args)
dist.check(*args)
pspace = SingleContinuousPSpace(symbol, dist)
if any(isinstance(arg, RandomSymbol) for arg in args):
pspace = JointPSpace(symbol, CompoundDistribution(dist))
return pspace.value
########################################
# Continuous Probability Distributions #
########################################
#-------------------------------------------------------------------------------
# Arcsin distribution ----------------------------------------------------------
class ArcsinDistribution(SingleContinuousDistribution):
_argnames = ('a', 'b')
def pdf(self, x):
return 1/(pi*sqrt((x - self.a)*(self.b - x)))
def _cdf(self, x):
from sympy import asin
a, b = self.a, self.b
return Piecewise(
(S.Zero, x < a),
(2*asin(sqrt((x - a)/(b - a)))/pi, x <= b),
(S.One, True))
def Arcsin(name, a=0, b=1):
r"""
Create a Continuous Random Variable with an arcsin distribution.
The density of the arcsin distribution is given by
.. math::
f(x) := \frac{1}{\pi\sqrt{(x-a)(b-x)}}
with :math:`x \in [a,b]`. It must hold that :math:`-\infty < a < b < \infty`.
Parameters
==========
a : Real number, the left interval boundary
b : Real number, the right interval boundary
Returns
=======
A RandomSymbol.
Examples
========
>>> from sympy.stats import Arcsin, density, cdf
>>> from sympy import Symbol, simplify
>>> a = Symbol("a", real=True)
>>> b = Symbol("b", real=True)
>>> z = Symbol("z")
>>> X = Arcsin("x", a, b)
>>> density(X)(z)
1/(pi*sqrt((-a + z)*(b - z)))
>>> cdf(X)(z)
Piecewise((0, a > z),
(2*asin(sqrt((-a + z)/(-a + b)))/pi, b >= z),
(1, True))
References
==========
.. [1] https://en.wikipedia.org/wiki/Arcsine_distribution
"""
return rv(name, ArcsinDistribution, (a, b))
#-------------------------------------------------------------------------------
# Benini distribution ----------------------------------------------------------
class BeniniDistribution(SingleContinuousDistribution):
_argnames = ('alpha', 'beta', 'sigma')
@property
def set(self):
return Interval(self.sigma, oo)
def pdf(self, x):
alpha, beta, sigma = self.alpha, self.beta, self.sigma
return (exp(-alpha*log(x/sigma) - beta*log(x/sigma)**2)
*(alpha/x + 2*beta*log(x/sigma)/x))
def _moment_generating_function(self, t):
raise NotImplementedError('The moment generating function of the '
'Benini distribution does not exist.')
def Benini(name, alpha, beta, sigma):
r"""
Create a Continuous Random Variable with a Benini distribution.
The density of the Benini distribution is given by
.. math::
f(x) := e^{-\alpha\log{\frac{x}{\sigma}}
-\beta\log^2\left[{\frac{x}{\sigma}}\right]}
\left(\frac{\alpha}{x}+\frac{2\beta\log{\frac{x}{\sigma}}}{x}\right)
This is a heavy-tailed distrubtion and is also known as the log-Rayleigh
distribution.
Parameters
==========
alpha : Real number, `\alpha > 0`, a shape
beta : Real number, `\beta > 0`, a shape
sigma : Real number, `\sigma > 0`, a scale
Returns
=======
A RandomSymbol.
Examples
========
>>> from sympy.stats import Benini, density
>>> from sympy import Symbol, simplify, pprint
>>> alpha = Symbol("alpha", positive=True)
>>> beta = Symbol("beta", positive=True)
>>> sigma = Symbol("sigma", positive=True)
>>> z = Symbol("z")
>>> X = Benini("x", alpha, beta, sigma)
>>> D = density(X)(z)
>>> pprint(D, use_unicode=False)
/ / z \\ / z \ 2/ z \
| 2*beta*log|-----|| - alpha*log|-----| - beta*log |-----|
|alpha \sigma/| \sigma/ \sigma/
|----- + -----------------|*e
\ z z /
References
==========
.. [1] https://en.wikipedia.org/wiki/Benini_distribution
.. [2] http://reference.wolfram.com/legacy/v8/ref/BeniniDistribution.html
"""
return rv(name, BeniniDistribution, (alpha, beta, sigma))
#-------------------------------------------------------------------------------
# Beta distribution ------------------------------------------------------------
class BetaDistribution(SingleContinuousDistribution):
_argnames = ('alpha', 'beta')
set = Interval(0, 1)
@staticmethod
def check(alpha, beta):
_value_check(alpha > 0, "Alpha must be positive")
_value_check(beta > 0, "Beta must be positive")
def pdf(self, x):
alpha, beta = self.alpha, self.beta
return x**(alpha - 1) * (1 - x)**(beta - 1) / beta_fn(alpha, beta)
def sample(self):
return random.betavariate(self.alpha, self.beta)
def _characteristic_function(self, t):
return hyper((self.alpha,), (self.alpha + self.beta,), I*t)
def _moment_generating_function(self, t):
return hyper((self.alpha,), (self.alpha + self.beta,), t)
def Beta(name, alpha, beta):
r"""
Create a Continuous Random Variable with a Beta distribution.
The density of the Beta distribution is given by
.. math::
f(x) := \frac{x^{\alpha-1}(1-x)^{\beta-1}} {\mathrm{B}(\alpha,\beta)}
with :math:`x \in [0,1]`.
Parameters
==========
alpha : real positive
A shape
beta : real positive
A shape
Returns
=======
A RandomSymbol.
Examples
========
>>> from sympy.stats import Beta, density, E, variance
>>> from sympy import Symbol, simplify, pprint, expand_func
>>> alpha = Symbol("alpha", positive=True)
>>> beta = Symbol("beta", positive=True)
>>> z = Symbol("z")
>>> X = Beta("x", alpha, beta)
>>> D = density(X)(z)
>>> pprint(D, use_unicode=False)
alpha - 1 beta - 1
z *(-z + 1)
---------------------------
B(alpha, beta)
>>> expand_func(simplify(E(X, meijerg=True)))
alpha/(alpha + beta)
>>> simplify(variance(X, meijerg=True)) #doctest: +SKIP
alpha*beta/((alpha + beta)**2*(alpha + beta + 1))
References
==========
.. [1] https://en.wikipedia.org/wiki/Beta_distribution
.. [2] http://mathworld.wolfram.com/BetaDistribution.html
"""
return rv(name, BetaDistribution, (alpha, beta))
#-------------------------------------------------------------------------------
# Beta prime distribution ------------------------------------------------------
class BetaPrimeDistribution(SingleContinuousDistribution):
_argnames = ('alpha', 'beta')
set = Interval(0, oo)
def pdf(self, x):
alpha, beta = self.alpha, self.beta
return x**(alpha - 1)*(1 + x)**(-alpha - beta)/beta_fn(alpha, beta)
def BetaPrime(name, alpha, beta):
r"""
Create a continuous random variable with a Beta prime distribution.
The density of the Beta prime distribution is given by
.. math::
f(x) := \frac{x^{\alpha-1} (1+x)^{-\alpha -\beta}}{B(\alpha,\beta)}
with :math:`x > 0`.
Parameters
==========
alpha : Real number, `\alpha > 0`, a shape
beta : Real number, `\beta > 0`, a shape
Returns
=======
A RandomSymbol.
Examples
========
>>> from sympy.stats import BetaPrime, density
>>> from sympy import Symbol, pprint
>>> alpha = Symbol("alpha", positive=True)
>>> beta = Symbol("beta", positive=True)
>>> z = Symbol("z")
>>> X = BetaPrime("x", alpha, beta)
>>> D = density(X)(z)
>>> pprint(D, use_unicode=False)
alpha - 1 -alpha - beta
z *(z + 1)
-------------------------------
B(alpha, beta)
References
==========
.. [1] https://en.wikipedia.org/wiki/Beta_prime_distribution
.. [2] http://mathworld.wolfram.com/BetaPrimeDistribution.html
"""
return rv(name, BetaPrimeDistribution, (alpha, beta))
#-------------------------------------------------------------------------------
# Cauchy distribution ----------------------------------------------------------
class CauchyDistribution(SingleContinuousDistribution):
_argnames = ('x0', 'gamma')
def pdf(self, x):
return 1/(pi*self.gamma*(1 + ((x - self.x0)/self.gamma)**2))
def _characteristic_function(self, t):
return exp(self.x0 * I * t - self.gamma * Abs(t))
def _moment_generating_function(self, t):
raise NotImplementedError("The moment generating function for the "
"Cauchy distribution does not exist.")
def Cauchy(name, x0, gamma):
r"""
Create a continuous random variable with a Cauchy distribution.
The density of the Cauchy distribution is given by
.. math::
f(x) := \frac{1}{\pi} \arctan\left(\frac{x-x_0}{\gamma}\right)
+\frac{1}{2}
Parameters
==========
x0 : real
The location
gamma : real positive
The scale
Returns
=======
A RandomSymbol.
Examples
========
>>> from sympy.stats import Cauchy, density
>>> from sympy import Symbol
>>> x0 = Symbol("x0")
>>> gamma = Symbol("gamma", positive=True)
>>> z = Symbol("z")
>>> X = Cauchy("x", x0, gamma)
>>> density(X)(z)
1/(pi*gamma*(1 + (-x0 + z)**2/gamma**2))
References
==========
.. [1] https://en.wikipedia.org/wiki/Cauchy_distribution
.. [2] http://mathworld.wolfram.com/CauchyDistribution.html
"""
return rv(name, CauchyDistribution, (x0, gamma))
#-------------------------------------------------------------------------------
# Chi distribution -------------------------------------------------------------
class ChiDistribution(SingleContinuousDistribution):
_argnames = ('k',)
set = Interval(0, oo)
def pdf(self, x):
return 2**(1 - self.k/2)*x**(self.k - 1)*exp(-x**2/2)/gamma(self.k/2)
def _characteristic_function(self, t):
k = self.k
part_1 = hyper((k/2,), (S(1)/2,), -t**2/2)
part_2 = I*t*sqrt(2)*gamma((k+1)/2)/gamma(k/2)
part_3 = hyper(((k+1)/2,), (S(3)/2,), -t**2/2)
return part_1 + part_2*part_3
def _moment_generating_function(self, t):
k = self.k
part_1 = hyper((k / 2,), (S(1) / 2,), t ** 2 / 2)
part_2 = t * sqrt(2) * gamma((k + 1) / 2) / gamma(k / 2)
part_3 = hyper(((k + 1) / 2,), (S(3) / 2,), t ** 2 / 2)
return part_1 + part_2 * part_3
def Chi(name, k):
r"""
Create a continuous random variable with a Chi distribution.
The density of the Chi distribution is given by
.. math::
f(x) := \frac{2^{1-k/2}x^{k-1}e^{-x^2/2}}{\Gamma(k/2)}
with :math:`x \geq 0`.
Parameters
==========
k : positive integer
The number of degrees of freedom
Returns
=======
A RandomSymbol.
Examples
========
>>> from sympy.stats import Chi, density, E, std
>>> from sympy import Symbol, simplify
>>> k = Symbol("k", integer=True)
>>> z = Symbol("z")
>>> X = Chi("x", k)
>>> density(X)(z)
2**(-k/2 + 1)*z**(k - 1)*exp(-z**2/2)/gamma(k/2)
References
==========
.. [1] https://en.wikipedia.org/wiki/Chi_distribution
.. [2] http://mathworld.wolfram.com/ChiDistribution.html
"""
return rv(name, ChiDistribution, (k,))
#-------------------------------------------------------------------------------
# Non-central Chi distribution -------------------------------------------------
class ChiNoncentralDistribution(SingleContinuousDistribution):
_argnames = ('k', 'l')
set = Interval(0, oo)
def pdf(self, x):
k, l = self.k, self.l
return exp(-(x**2+l**2)/2)*x**k*l / (l*x)**(k/2) * besseli(k/2-1, l*x)
def ChiNoncentral(name, k, l):
r"""
Create a continuous random variable with a non-central Chi distribution.
The density of the non-central Chi distribution is given by
.. math::
f(x) := \frac{e^{-(x^2+\lambda^2)/2} x^k\lambda}
{(\lambda x)^{k/2}} I_{k/2-1}(\lambda x)
with `x \geq 0`. Here, `I_\nu (x)` is the
:ref:`modified Bessel function of the first kind <besseli>`.
Parameters
==========
k : A positive Integer, `k > 0`, the number of degrees of freedom
l : Shift parameter
Returns
=======
A RandomSymbol.
Examples
========
>>> from sympy.stats import ChiNoncentral, density, E, std
>>> from sympy import Symbol, simplify
>>> k = Symbol("k", integer=True)
>>> l = Symbol("l")
>>> z = Symbol("z")
>>> X = ChiNoncentral("x", k, l)
>>> density(X)(z)
l*z**k*(l*z)**(-k/2)*exp(-l**2/2 - z**2/2)*besseli(k/2 - 1, l*z)
References
==========
.. [1] https://en.wikipedia.org/wiki/Noncentral_chi_distribution
"""
return rv(name, ChiNoncentralDistribution, (k, l))
#-------------------------------------------------------------------------------
# Chi squared distribution -----------------------------------------------------
class ChiSquaredDistribution(SingleContinuousDistribution):
_argnames = ('k',)
set = Interval(0, oo)
def pdf(self, x):
k = self.k
return 1/(2**(k/2)*gamma(k/2))*x**(k/2 - 1)*exp(-x/2)
def _cdf(self, x):
k = self.k
return Piecewise(
(S.One/gamma(k/2)*lowergamma(k/2, x/2), x >= 0),
(0, True)
)
def _characteristic_function(self, t):
return (1 - 2*I*t)**(-self.k/2)
def _moment_generating_function(self, t):
return (1 - 2*t)**(-self.k/2)
def ChiSquared(name, k):
r"""
Create a continuous random variable with a Chi-squared distribution.
The density of the Chi-squared distribution is given by
.. math::
f(x) := \frac{1}{2^{\frac{k}{2}}\Gamma\left(\frac{k}{2}\right)}
x^{\frac{k}{2}-1} e^{-\frac{x}{2}}
with :math:`x \geq 0`.
Parameters
==========
k : positive integer
The number of degrees of freedom
Returns
=======
A RandomSymbol.
Examples
========
>>> from sympy.stats import ChiSquared, density, E, variance
>>> from sympy import Symbol, simplify, gammasimp, expand_func
>>> k = Symbol("k", integer=True, positive=True)
>>> z = Symbol("z")
>>> X = ChiSquared("x", k)
>>> density(X)(z)
2**(-k/2)*z**(k/2 - 1)*exp(-z/2)/gamma(k/2)
>>> gammasimp(E(X))
k
>>> simplify(expand_func(variance(X)))
2*k
References
==========
.. [1] https://en.wikipedia.org/wiki/Chi_squared_distribution
.. [2] http://mathworld.wolfram.com/Chi-SquaredDistribution.html
"""
return rv(name, ChiSquaredDistribution, (k, ))
#-------------------------------------------------------------------------------
# Dagum distribution -----------------------------------------------------------
class DagumDistribution(SingleContinuousDistribution):
_argnames = ('p', 'a', 'b')
def pdf(self, x):
p, a, b = self.p, self.a, self.b
return a*p/x*((x/b)**(a*p)/(((x/b)**a + 1)**(p + 1)))
def _cdf(self, x):
p, a, b = self.p, self.a, self.b
return Piecewise(((S.One + (S(x)/b)**-a)**-p, x>=0),
(S.Zero, True))
def Dagum(name, p, a, b):
r"""
Create a continuous random variable with a Dagum distribution.
The density of the Dagum distribution is given by
.. math::
f(x) := \frac{a p}{x} \left( \frac{\left(\tfrac{x}{b}\right)^{a p}}
{\left(\left(\tfrac{x}{b}\right)^a + 1 \right)^{p+1}} \right)
with :math:`x > 0`.
Parameters
==========
p : Real number, `p > 0`, a shape
a : Real number, `a > 0`, a shape
b : Real number, `b > 0`, a scale
Returns
=======
A RandomSymbol.
Examples
========
>>> from sympy.stats import Dagum, density, cdf
>>> from sympy import Symbol, simplify
>>> p = Symbol("p", positive=True)
>>> b = Symbol("b", positive=True)
>>> a = Symbol("a", positive=True)
>>> z = Symbol("z")
>>> X = Dagum("x", p, a, b)
>>> density(X)(z)
a*p*(z/b)**(a*p)*((z/b)**a + 1)**(-p - 1)/z
>>> cdf(X)(z)
Piecewise(((1 + (z/b)**(-a))**(-p), z >= 0), (0, True))
References
==========
.. [1] https://en.wikipedia.org/wiki/Dagum_distribution
"""
return rv(name, DagumDistribution, (p, a, b))
#-------------------------------------------------------------------------------
# Erlang distribution ----------------------------------------------------------
def Erlang(name, k, l):
r"""
Create a continuous random variable with an Erlang distribution.
The density of the Erlang distribution is given by
.. math::
f(x) := \frac{\lambda^k x^{k-1} e^{-\lambda x}}{(k-1)!}
with :math:`x \in [0,\infty]`.
Parameters
==========
k : Integer
l : Real number, `\lambda > 0`, the rate
Returns
=======
A RandomSymbol.
Examples
========
>>> from sympy.stats import Erlang, density, cdf, E, variance
>>> from sympy import Symbol, simplify, pprint
>>> k = Symbol("k", integer=True, positive=True)
>>> l = Symbol("l", positive=True)
>>> z = Symbol("z")
>>> X = Erlang("x", k, l)
>>> D = density(X)(z)
>>> pprint(D, use_unicode=False)
k k - 1 -l*z
l *z *e
---------------
Gamma(k)
>>> C = cdf(X, meijerg=True)(z)
>>> pprint(C, use_unicode=False)
/ -2*I*pi*k
|k*e *lowergamma(k, l*z)
|------------------------------- for z >= 0
< Gamma(k + 1)
|
| 0 otherwise
\
>>> simplify(E(X))
k/l
>>> simplify(variance(X))
k/l**2
References
==========
.. [1] https://en.wikipedia.org/wiki/Erlang_distribution
.. [2] http://mathworld.wolfram.com/ErlangDistribution.html
"""
return rv(name, GammaDistribution, (k, S.One/l))
#-------------------------------------------------------------------------------
# Exponential distribution -----------------------------------------------------
class ExponentialDistribution(SingleContinuousDistribution):
_argnames = ('rate',)
set = Interval(0, oo)
@staticmethod
def check(rate):
_value_check(rate > 0, "Rate must be positive.")
def pdf(self, x):
return self.rate * exp(-self.rate*x)
def sample(self):
return random.expovariate(self.rate)
def _cdf(self, x):
return Piecewise(
(S.One - exp(-self.rate*x), x >= 0),
(0, True),
)
def _characteristic_function(self, t):
rate = self.rate
return rate / (rate - I*t)
def _moment_generating_function(self, t):
rate = self.rate
return rate / (rate - t)
def Exponential(name, rate):
r"""
Create a continuous random variable with an Exponential distribution.
The density of the exponential distribution is given by
.. math::
f(x) := \lambda \exp(-\lambda x)
with `x > 0`. Note that the expected value is `1/\lambda`.
Parameters
==========
rate : A positive Real number, `\lambda > 0`, the rate (or inverse scale/inverse mean)
Returns
=======
A RandomSymbol.
Examples
========
>>> from sympy.stats import Exponential, density, cdf, E
>>> from sympy.stats import variance, std, skewness
>>> from sympy import Symbol
>>> l = Symbol("lambda", positive=True)
>>> z = Symbol("z")
>>> X = Exponential("x", l)
>>> density(X)(z)
lambda*exp(-lambda*z)
>>> cdf(X)(z)
Piecewise((1 - exp(-lambda*z), z >= 0), (0, True))
>>> E(X)
1/lambda
>>> variance(X)
lambda**(-2)
>>> skewness(X)
2
>>> X = Exponential('x', 10)
>>> density(X)(z)
10*exp(-10*z)
>>> E(X)
1/10
>>> std(X)
1/10
References
==========
.. [1] https://en.wikipedia.org/wiki/Exponential_distribution
.. [2] http://mathworld.wolfram.com/ExponentialDistribution.html
"""
return rv(name, ExponentialDistribution, (rate, ))
#-------------------------------------------------------------------------------
# F distribution ---------------------------------------------------------------
class FDistributionDistribution(SingleContinuousDistribution):
_argnames = ('d1', 'd2')
set = Interval(0, oo)
def pdf(self, x):
d1, d2 = self.d1, self.d2
return (sqrt((d1*x)**d1*d2**d2 / (d1*x+d2)**(d1+d2))
/ (x * beta_fn(d1/2, d2/2)))
def _moment_generating_function(self, t):
raise NotImplementedError('The moment generating function for the '
'F-distribution does not exist.')
def FDistribution(name, d1, d2):
r"""
Create a continuous random variable with a F distribution.
The density of the F distribution is given by
.. math::
f(x) := \frac{\sqrt{\frac{(d_1 x)^{d_1} d_2^{d_2}}
{(d_1 x + d_2)^{d_1 + d_2}}}}
{x \mathrm{B} \left(\frac{d_1}{2}, \frac{d_2}{2}\right)}
with :math:`x > 0`.
Parameters
==========
d1 : `d_1 > 0`, where d_1 is the degrees of freedom (n_1 - 1)
d2 : `d_2 > 0`, where d_2 is the degrees of freedom (n_2 - 1)
Returns
=======
A RandomSymbol.
Examples
========
>>> from sympy.stats import FDistribution, density
>>> from sympy import Symbol, simplify, pprint
>>> d1 = Symbol("d1", positive=True)
>>> d2 = Symbol("d2", positive=True)
>>> z = Symbol("z")
>>> X = FDistribution("x", d1, d2)
>>> D = density(X)(z)
>>> pprint(D, use_unicode=False)
d2
-- ______________________________
2 / d1 -d1 - d2
d2 *\/ (d1*z) *(d1*z + d2)
--------------------------------------
/d1 d2\
z*B|--, --|
\2 2 /
References
==========
.. [1] https://en.wikipedia.org/wiki/F-distribution
.. [2] http://mathworld.wolfram.com/F-Distribution.html
"""
return rv(name, FDistributionDistribution, (d1, d2))
#-------------------------------------------------------------------------------
# Fisher Z distribution --------------------------------------------------------
class FisherZDistribution(SingleContinuousDistribution):
_argnames = ('d1', 'd2')
def pdf(self, x):
d1, d2 = self.d1, self.d2
return (2*d1**(d1/2)*d2**(d2/2) / beta_fn(d1/2, d2/2) *
exp(d1*x) / (d1*exp(2*x)+d2)**((d1+d2)/2))
def FisherZ(name, d1, d2):
r"""
Create a Continuous Random Variable with an Fisher's Z distribution.
The density of the Fisher's Z distribution is given by
.. math::
f(x) := \frac{2d_1^{d_1/2} d_2^{d_2/2}} {\mathrm{B}(d_1/2, d_2/2)}
\frac{e^{d_1z}}{\left(d_1e^{2z}+d_2\right)^{\left(d_1+d_2\right)/2}}
.. TODO - What is the difference between these degrees of freedom?
Parameters
==========
d1 : `d_1 > 0`, degree of freedom
d2 : `d_2 > 0`, degree of freedom
Returns
=======
A RandomSymbol.
Examples
========
>>> from sympy.stats import FisherZ, density
>>> from sympy import Symbol, simplify, pprint
>>> d1 = Symbol("d1", positive=True)
>>> d2 = Symbol("d2", positive=True)
>>> z = Symbol("z")
>>> X = FisherZ("x", d1, d2)
>>> D = density(X)(z)
>>> pprint(D, use_unicode=False)
d1 d2
d1 d2 - -- - --
-- -- 2 2
2 2 / 2*z \ d1*z
2*d1 *d2 *\d1*e + d2/ *e
-----------------------------------------
/d1 d2\
B|--, --|
\2 2 /
References
==========
.. [1] https://en.wikipedia.org/wiki/Fisher%27s_z-distribution
.. [2] http://mathworld.wolfram.com/Fishersz-Distribution.html
"""
return rv(name, FisherZDistribution, (d1, d2))
#-------------------------------------------------------------------------------
# Frechet distribution ---------------------------------------------------------
class FrechetDistribution(SingleContinuousDistribution):
_argnames = ('a', 's', 'm')
set = Interval(0, oo)
def __new__(cls, a, s=1, m=0):
a, s, m = list(map(sympify, (a, s, m)))
return Basic.__new__(cls, a, s, m)
def pdf(self, x):
a, s, m = self.a, self.s, self.m
return a/s * ((x-m)/s)**(-1-a) * exp(-((x-m)/s)**(-a))
def _cdf(self, x):
a, s, m = self.a, self.s, self.m
return Piecewise((exp(-((x-m)/s)**(-a)), x >= m),
(S.Zero, True))
def Frechet(name, a, s=1, m=0):
r"""
Create a continuous random variable with a Frechet distribution.
The density of the Frechet distribution is given by
.. math::
f(x) := \frac{\alpha}{s} \left(\frac{x-m}{s}\right)^{-1-\alpha}
e^{-(\frac{x-m}{s})^{-\alpha}}
with :math:`x \geq m`.
Parameters
==========
a : Real number, :math:`a \in \left(0, \infty\right)` the shape
s : Real number, :math:`s \in \left(0, \infty\right)` the scale
m : Real number, :math:`m \in \left(-\infty, \infty\right)` the minimum
Returns
=======
A RandomSymbol.
Examples
========
>>> from sympy.stats import Frechet, density, E, std, cdf
>>> from sympy import Symbol, simplify
>>> a = Symbol("a", positive=True)
>>> s = Symbol("s", positive=True)
>>> m = Symbol("m", real=True)
>>> z = Symbol("z")
>>> X = Frechet("x", a, s, m)
>>> density(X)(z)
a*((-m + z)/s)**(-a - 1)*exp(-((-m + z)/s)**(-a))/s
>>> cdf(X)(z)
Piecewise((exp(-((-m + z)/s)**(-a)), m <= z), (0, True))
References
==========
.. [1] https://en.wikipedia.org/wiki/Fr%C3%A9chet_distribution
"""
return rv(name, FrechetDistribution, (a, s, m))
#-------------------------------------------------------------------------------
# Gamma distribution -----------------------------------------------------------
class GammaDistribution(SingleContinuousDistribution):
_argnames = ('k', 'theta')
set = Interval(0, oo)
@staticmethod
def check(k, theta):
_value_check(k > 0, "k must be positive")
_value_check(theta > 0, "Theta must be positive")
def pdf(self, x):
k, theta = self.k, self.theta
return x**(k - 1) * exp(-x/theta) / (gamma(k)*theta**k)
def sample(self):
return random.gammavariate(self.k, self.theta)
def _cdf(self, x):
k, theta = self.k, self.theta
return Piecewise(
(lowergamma(k, S(x)/theta)/gamma(k), x > 0),
(S.Zero, True))
def _characteristic_function(self, t):
return (1 - self.theta*I*t)**(-self.k)
def _moment_generating_function(self, t):
return (1- self.theta*t)**(-self.k)
def Gamma(name, k, theta):
r"""
Create a continuous random variable with a Gamma distribution.
The density of the Gamma distribution is given by
.. math::
f(x) := \frac{1}{\Gamma(k) \theta^k} x^{k - 1} e^{-\frac{x}{\theta}}
with :math:`x \in [0,1]`.
Parameters
==========
k : Real number, `k > 0`, a shape
theta : Real number, `\theta > 0`, a scale
Returns
=======
A RandomSymbol.
Examples
========
>>> from sympy.stats import Gamma, density, cdf, E, variance
>>> from sympy import Symbol, pprint, simplify
>>> k = Symbol("k", positive=True)
>>> theta = Symbol("theta", positive=True)
>>> z = Symbol("z")
>>> X = Gamma("x", k, theta)
>>> D = density(X)(z)
>>> pprint(D, use_unicode=False)
-z
-----
-k k - 1 theta
theta *z *e
---------------------
Gamma(k)
>>> C = cdf(X, meijerg=True)(z)
>>> pprint(C, use_unicode=False)
/ / z \
|k*lowergamma|k, -----|
| \ theta/
<---------------------- for z >= 0
| Gamma(k + 1)
|
\ 0 otherwise
>>> E(X)
k*theta
>>> V = simplify(variance(X))
>>> pprint(V, use_unicode=False)
2
k*theta
References
==========
.. [1] https://en.wikipedia.org/wiki/Gamma_distribution
.. [2] http://mathworld.wolfram.com/GammaDistribution.html
"""
return rv(name, GammaDistribution, (k, theta))
#-------------------------------------------------------------------------------
# Inverse Gamma distribution ---------------------------------------------------
class GammaInverseDistribution(SingleContinuousDistribution):
_argnames = ('a', 'b')
set = Interval(0, oo)
@staticmethod
def check(a, b):
_value_check(a > 0, "alpha must be positive")
_value_check(b > 0, "beta must be positive")
def pdf(self, x):
a, b = self.a, self.b
return b**a/gamma(a) * x**(-a-1) * exp(-b/x)
def _cdf(self, x):
a, b = self.a, self.b
return Piecewise((uppergamma(a,b/x)/gamma(a), x > 0),
(S.Zero, True))
def sample(self):
scipy = import_module('scipy')
if scipy:
from scipy.stats import invgamma
return invgamma.rvs(float(self.a), 0, float(self.b))
else:
raise NotImplementedError('Sampling the inverse Gamma Distribution requires Scipy.')
def _characteristic_function(self, t):
a, b = self.a, self.b
return 2 * (-I*b*t)**(a/2) * besselk(sqrt(-4*I*b*t)) / gamma(a)
def _moment_generating_function(self, t):
raise NotImplementedError('The moment generating function for the '
'gamma inverse distribution does not exist.')
def GammaInverse(name, a, b):
r"""
Create a continuous random variable with an inverse Gamma distribution.
The density of the inverse Gamma distribution is given by
.. math::
f(x) := \frac{\beta^\alpha}{\Gamma(\alpha)} x^{-\alpha - 1}
\exp\left(\frac{-\beta}{x}\right)
with :math:`x > 0`.
Parameters
==========
a : Real number, `a > 0` a shape
b : Real number, `b > 0` a scale
Returns
=======
A RandomSymbol.
Examples
========
>>> from sympy.stats import GammaInverse, density, cdf, E, variance
>>> from sympy import Symbol, pprint
>>> a = Symbol("a", positive=True)
>>> b = Symbol("b", positive=True)
>>> z = Symbol("z")
>>> X = GammaInverse("x", a, b)
>>> D = density(X)(z)
>>> pprint(D, use_unicode=False)
-b
---
a -a - 1 z
b *z *e
---------------
Gamma(a)
>>> cdf(X)(z)
Piecewise((uppergamma(a, b/z)/gamma(a), z > 0), (0, True))
References
==========
.. [1] https://en.wikipedia.org/wiki/Inverse-gamma_distribution
"""
return rv(name, GammaInverseDistribution, (a, b))
#-------------------------------------------------------------------------------
# Gumbel distribution --------------------------------------------------------
class GumbelDistribution(SingleContinuousDistribution):
_argnames = ('beta', 'mu')
set = Interval(-oo, oo)
def pdf(self, x):
beta, mu = self.beta, self.mu
return (1/beta)*exp(-((x-mu)/beta)+exp(-((x-mu)/beta)))
def _characteristic_function(self, t):
return gamma(1 - I*self.beta*t) * exp(I*self.mu*t)
def _moment_generating_function(self, t):
return gamma(1 - self.beta*t) * exp(I*self.mu*t)
def Gumbel(name, beta, mu):
r"""
Create a Continuous Random Variable with Gumbel distribution.
The density of the Gumbel distribution is given by
.. math::
f(x) := \exp \left( -exp \left( x + \exp \left( -x \right) \right) \right)
with ::math 'x \in [ - \inf, \inf ]'.
Parameters
==========
mu: Real number, 'mu' is a location
beta: Real number, 'beta > 0' is a scale
Returns
==========
A RandomSymbol
Examples
==========
>>> from sympy.stats import Gumbel, density, E, variance
>>> from sympy import Symbol, simplify, pprint
>>> x = Symbol("x")
>>> mu = Symbol("mu")
>>> beta = Symbol("beta", positive=True)
>>> X = Gumbel("x", beta, mu)
>>> density(X)(x)
exp(exp(-(-mu + x)/beta) - (-mu + x)/beta)/beta
References
==========
.. [1] http://mathworld.wolfram.com/GumbelDistribution.html
.. [2] https://en.wikipedia.org/wiki/Gumbel_distribution
"""
return rv(name, GumbelDistribution, (beta, mu))
#-------------------------------------------------------------------------------
# Gompertz distribution --------------------------------------------------------
class GompertzDistribution(SingleContinuousDistribution):
_argnames = ('b', 'eta')
set = Interval(0, oo)
@staticmethod
def check(b, eta):
_value_check(b > 0, "b must be positive")
_value_check(eta > 0, "eta must be positive")
def pdf(self, x):
eta, b = self.eta, self.b
return b*eta*exp(b*x)*exp(eta)*exp(-eta*exp(b*x))
def _moment_generating_function(self, t):
eta, b = self.eta, self.b
return eta * exp(eta) * expint(t/b, eta)
def Gompertz(name, b, eta):
r"""
Create a Continuous Random Variable with Gompertz distribution.
The density of the Gompertz distribution is given by
.. math::
f(x) := b \eta e^{b x} e^{\eta} \exp \left(-\eta e^{bx} \right)
with :math: 'x \in [0, \inf)'.
Parameters
==========
b: Real number, 'b > 0' a scale
eta: Real number, 'eta > 0' a shape
Returns
=======
A RandomSymbol.
Examples
========
>>> from sympy.stats import Gompertz, density, E, variance
>>> from sympy import Symbol, simplify, pprint
>>> b = Symbol("b", positive=True)
>>> eta = Symbol("eta", positive=True)
>>> z = Symbol("z")
>>> X = Gompertz("x", b, eta)
>>> density(X)(z)
b*eta*exp(eta)*exp(b*z)*exp(-eta*exp(b*z))
References
==========
.. [1] https://en.wikipedia.org/wiki/Gompertz_distribution
"""
return rv(name, GompertzDistribution, (b, eta))
#-------------------------------------------------------------------------------
# Kumaraswamy distribution -----------------------------------------------------
class KumaraswamyDistribution(SingleContinuousDistribution):
_argnames = ('a', 'b')
set = Interval(0, oo)
@staticmethod
def check(a, b):
_value_check(a > 0, "a must be positive")
_value_check(b > 0, "b must be positive")
def pdf(self, x):
a, b = self.a, self.b
return a * b * x**(a-1) * (1-x**a)**(b-1)
def _cdf(self, x):
a, b = self.a, self.b
return Piecewise(
(S.Zero, x < S.Zero),
(1 - (1 - x**a)**b, x <= S.One),
(S.One, True))
def Kumaraswamy(name, a, b):
r"""
Create a Continuous Random Variable with a Kumaraswamy distribution.
The density of the Kumaraswamy distribution is given by
.. math::
f(x) := a b x^{a-1} (1-x^a)^{b-1}
with :math:`x \in [0,1]`.
Parameters
==========
a : Real number, `a > 0` a shape
b : Real number, `b > 0` a shape
Returns
=======
A RandomSymbol.
Examples
========
>>> from sympy.stats import Kumaraswamy, density, E, variance, cdf
>>> from sympy import Symbol, simplify, pprint
>>> a = Symbol("a", positive=True)
>>> b = Symbol("b", positive=True)
>>> z = Symbol("z")
>>> X = Kumaraswamy("x", a, b)
>>> D = density(X)(z)
>>> pprint(D, use_unicode=False)
b - 1
a - 1 / a \
a*b*z *\- z + 1/
>>> cdf(X)(z)
Piecewise((0, z < 0),
(-(-z**a + 1)**b + 1, z <= 1),
(1, True))
References
==========
.. [1] https://en.wikipedia.org/wiki/Kumaraswamy_distribution
"""
return rv(name, KumaraswamyDistribution, (a, b))
#-------------------------------------------------------------------------------
# Laplace distribution ---------------------------------------------------------
class LaplaceDistribution(SingleContinuousDistribution):
_argnames = ('mu', 'b')
def pdf(self, x):
mu, b = self.mu, self.b
return 1/(2*b)*exp(-Abs(x - mu)/b)
def _cdf(self, x):
mu, b = self.mu, self.b
return Piecewise(
(S.Half*exp((x - mu)/b), x < mu),
(S.One - S.Half*exp(-(x - mu)/b), x >= mu)
)
def _characteristic_function(self, t):
return exp(self.mu*I*t) / (1 + self.b**2*t**2)
def _moment_generating_function(self, t):
return exp(self.mu*t) / (1 - self.b**2*t**2)
def Laplace(name, mu, b):
r"""
Create a continuous random variable with a Laplace distribution.
The density of the Laplace distribution is given by
.. math::
f(x) := \frac{1}{2 b} \exp \left(-\frac{|x-\mu|}b \right)
Parameters
==========
mu : Real number or a list/matrix, the location (mean) or the
location vector
b : Real number or a positive definite matrix, representing a scale
or the covariance matrix.
Returns
=======
A RandomSymbol.
Examples
========
>>> from sympy.stats import Laplace, density, cdf
>>> from sympy import Symbol, pprint
>>> mu = Symbol("mu")
>>> b = Symbol("b", positive=True)
>>> z = Symbol("z")
>>> X = Laplace("x", mu, b)
>>> density(X)(z)
exp(-Abs(mu - z)/b)/(2*b)
>>> cdf(X)(z)
Piecewise((exp((-mu + z)/b)/2, mu > z),
(-exp((mu - z)/b)/2 + 1, True))
>>> L = Laplace('L', [1, 2], [[1, 0], [0, 1]])
>>> pprint(density(L)(1, 2), use_unicode=False)
5 / ____\
e *besselk\0, \/ 35 /
---------------------
pi
References
==========
.. [1] https://en.wikipedia.org/wiki/Laplace_distribution
.. [2] http://mathworld.wolfram.com/LaplaceDistribution.html
"""
if isinstance(mu, (list, MatrixBase)) and\
isinstance(b, (list, MatrixBase)):
from sympy.stats.joint_rv_types import MultivariateLaplaceDistribution
return multivariate_rv(
MultivariateLaplaceDistribution, name, mu, b)
return rv(name, LaplaceDistribution, (mu, b))
#-------------------------------------------------------------------------------
# Logistic distribution --------------------------------------------------------
class LogisticDistribution(SingleContinuousDistribution):
_argnames = ('mu', 's')
def pdf(self, x):
mu, s = self.mu, self.s
return exp(-(x - mu)/s)/(s*(1 + exp(-(x - mu)/s))**2)
def _cdf(self, x):
mu, s = self.mu, self.s
return S.One/(1 + exp(-(x - mu)/s))
def _characteristic_function(self, t):
return Piecewise((exp(I*t*self.mu) * pi*self.s*t / sinh(pi*self.s*t), Ne(t, 0)), (S.One, True))
def _moment_generating_function(self, t):
return exp(self.mu*t) * Beta(1 - self.s*t, 1 + self.s*t)
def Logistic(name, mu, s):
r"""
Create a continuous random variable with a logistic distribution.
The density of the logistic distribution is given by
.. math::
f(x) := \frac{e^{-(x-\mu)/s}} {s\left(1+e^{-(x-\mu)/s}\right)^2}
Parameters
==========
mu : Real number, the location (mean)
s : Real number, `s > 0` a scale
Returns
=======
A RandomSymbol.
Examples
========
>>> from sympy.stats import Logistic, density, cdf
>>> from sympy import Symbol
>>> mu = Symbol("mu", real=True)
>>> s = Symbol("s", positive=True)
>>> z = Symbol("z")
>>> X = Logistic("x", mu, s)
>>> density(X)(z)
exp((mu - z)/s)/(s*(exp((mu - z)/s) + 1)**2)
>>> cdf(X)(z)
1/(exp((mu - z)/s) + 1)
References
==========
.. [1] https://en.wikipedia.org/wiki/Logistic_distribution
.. [2] http://mathworld.wolfram.com/LogisticDistribution.html
"""
return rv(name, LogisticDistribution, (mu, s))
#-------------------------------------------------------------------------------
# Log Normal distribution ------------------------------------------------------
class LogNormalDistribution(SingleContinuousDistribution):
_argnames = ('mean', 'std')
set = Interval(0, oo)
def pdf(self, x):
mean, std = self.mean, self.std
return exp(-(log(x) - mean)**2 / (2*std**2)) / (x*sqrt(2*pi)*std)
def sample(self):
return random.lognormvariate(self.mean, self.std)
def _cdf(self, x):
mean, std = self.mean, self.std
return Piecewise(
(S.Half + S.Half*erf((log(x) - mean)/sqrt(2)/std), x > 0),
(S.Zero, True)
)
def _moment_generating_function(self, t):
raise NotImplementedError('Moment generating function of the log-normal distribution is not defined.')
def LogNormal(name, mean, std):
r"""
Create a continuous random variable with a log-normal distribution.
The density of the log-normal distribution is given by
.. math::
f(x) := \frac{1}{x\sqrt{2\pi\sigma^2}}
e^{-\frac{\left(\ln x-\mu\right)^2}{2\sigma^2}}
with :math:`x \geq 0`.
Parameters
==========
mu : Real number, the log-scale
sigma : Real number, :math:`\sigma^2 > 0` a shape
Returns
=======
A RandomSymbol.
Examples
========
>>> from sympy.stats import LogNormal, density
>>> from sympy import Symbol, simplify, pprint
>>> mu = Symbol("mu", real=True)
>>> sigma = Symbol("sigma", positive=True)
>>> z = Symbol("z")
>>> X = LogNormal("x", mu, sigma)
>>> D = density(X)(z)
>>> pprint(D, use_unicode=False)
2
-(-mu + log(z))
-----------------
2
___ 2*sigma
\/ 2 *e
------------------------
____
2*\/ pi *sigma*z
>>> X = LogNormal('x', 0, 1) # Mean 0, standard deviation 1
>>> density(X)(z)
sqrt(2)*exp(-log(z)**2/2)/(2*sqrt(pi)*z)
References
==========
.. [1] https://en.wikipedia.org/wiki/Lognormal
.. [2] http://mathworld.wolfram.com/LogNormalDistribution.html
"""
return rv(name, LogNormalDistribution, (mean, std))
#-------------------------------------------------------------------------------
# Maxwell distribution ---------------------------------------------------------
class MaxwellDistribution(SingleContinuousDistribution):
_argnames = ('a',)
set = Interval(0, oo)
def pdf(self, x):
a = self.a
return sqrt(2/pi)*x**2*exp(-x**2/(2*a**2))/a**3
def Maxwell(name, a):
r"""
Create a continuous random variable with a Maxwell distribution.
The density of the Maxwell distribution is given by
.. math::
f(x) := \sqrt{\frac{2}{\pi}} \frac{x^2 e^{-x^2/(2a^2)}}{a^3}
with :math:`x \geq 0`.
.. TODO - what does the parameter mean?
Parameters
==========
a : Real number, `a > 0`
Returns
=======
A RandomSymbol.
Examples
========
>>> from sympy.stats import Maxwell, density, E, variance
>>> from sympy import Symbol, simplify
>>> a = Symbol("a", positive=True)
>>> z = Symbol("z")
>>> X = Maxwell("x", a)
>>> density(X)(z)
sqrt(2)*z**2*exp(-z**2/(2*a**2))/(sqrt(pi)*a**3)
>>> E(X)
2*sqrt(2)*a/sqrt(pi)
>>> simplify(variance(X))
a**2*(-8 + 3*pi)/pi
References
==========
.. [1] https://en.wikipedia.org/wiki/Maxwell_distribution
.. [2] http://mathworld.wolfram.com/MaxwellDistribution.html
"""
return rv(name, MaxwellDistribution, (a, ))
#-------------------------------------------------------------------------------
# Nakagami distribution --------------------------------------------------------
class NakagamiDistribution(SingleContinuousDistribution):
_argnames = ('mu', 'omega')
set = Interval(0, oo)
def pdf(self, x):
mu, omega = self.mu, self.omega
return 2*mu**mu/(gamma(mu)*omega**mu)*x**(2*mu - 1)*exp(-mu/omega*x**2)
def _cdf(self, x):
mu, omega = self.mu, self.omega
return Piecewise(
(lowergamma(mu, (mu/omega)*x**2)/gamma(mu), x > 0),
(S.Zero, True))
def Nakagami(name, mu, omega):
r"""
Create a continuous random variable with a Nakagami distribution.
The density of the Nakagami distribution is given by
.. math::
f(x) := \frac{2\mu^\mu}{\Gamma(\mu)\omega^\mu} x^{2\mu-1}
\exp\left(-\frac{\mu}{\omega}x^2 \right)
with :math:`x > 0`.
Parameters
==========
mu : Real number, `\mu \geq \frac{1}{2}` a shape
omega : Real number, `\omega > 0`, the spread
Returns
=======
A RandomSymbol.
Examples
========
>>> from sympy.stats import Nakagami, density, E, variance, cdf
>>> from sympy import Symbol, simplify, pprint
>>> mu = Symbol("mu", positive=True)
>>> omega = Symbol("omega", positive=True)
>>> z = Symbol("z")
>>> X = Nakagami("x", mu, omega)
>>> D = density(X)(z)
>>> pprint(D, use_unicode=False)
2
-mu*z
-------
mu -mu 2*mu - 1 omega
2*mu *omega *z *e
----------------------------------
Gamma(mu)
>>> simplify(E(X))
sqrt(mu)*sqrt(omega)*gamma(mu + 1/2)/gamma(mu + 1)
>>> V = simplify(variance(X))
>>> pprint(V, use_unicode=False)
2
omega*Gamma (mu + 1/2)
omega - -----------------------
Gamma(mu)*Gamma(mu + 1)
>>> cdf(X)(z)
Piecewise((lowergamma(mu, mu*z**2/omega)/gamma(mu), z > 0),
(0, True))
References
==========
.. [1] https://en.wikipedia.org/wiki/Nakagami_distribution
"""
return rv(name, NakagamiDistribution, (mu, omega))
#-------------------------------------------------------------------------------
# Normal distribution ----------------------------------------------------------
class NormalDistribution(SingleContinuousDistribution):
_argnames = ('mean', 'std')
@staticmethod
def check(mean, std):
_value_check(std > 0, "Standard deviation must be positive")
def pdf(self, x):
return exp(-(x - self.mean)**2 / (2*self.std**2)) / (sqrt(2*pi)*self.std)
def sample(self):
return random.normalvariate(self.mean, self.std)
def _cdf(self, x):
mean, std = self.mean, self.std
return erf(sqrt(2)*(-mean + x)/(2*std))/2 + S.Half
def _characteristic_function(self, t):
mean, std = self.mean, self.std
return exp(I*mean*t - std**2*t**2/2)
def _moment_generating_function(self, t):
mean, std = self.mean, self.std
return exp(mean*t + std**2*t**2/2)
def Normal(name, mean, std):
r"""
Create a continuous random variable with a Normal distribution.
The density of the Normal distribution is given by
.. math::
f(x) := \frac{1}{\sigma\sqrt{2\pi}} e^{ -\frac{(x-\mu)^2}{2\sigma^2} }
Parameters
==========
mu : Real number or a list representing the mean or the mean vector
sigma : Real number or a positive definite sqaure matrix,
:math:`\sigma^2 > 0` the variance
Returns
=======
A RandomSymbol.
Examples
========
>>> from sympy.stats import Normal, density, E, std, cdf, skewness
>>> from sympy import Symbol, simplify, pprint, factor, together, factor_terms
>>> mu = Symbol("mu")
>>> sigma = Symbol("sigma", positive=True)
>>> z = Symbol("z")
>>> y = Symbol("y")
>>> X = Normal("x", mu, sigma)
>>> density(X)(z)
sqrt(2)*exp(-(-mu + z)**2/(2*sigma**2))/(2*sqrt(pi)*sigma)
>>> C = simplify(cdf(X))(z) # it needs a little more help...
>>> pprint(C, use_unicode=False)
/ ___ \
|\/ 2 *(-mu + z)|
erf|---------------|
\ 2*sigma / 1
-------------------- + -
2 2
>>> simplify(skewness(X))
0
>>> X = Normal("x", 0, 1) # Mean 0, standard deviation 1
>>> density(X)(z)
sqrt(2)*exp(-z**2/2)/(2*sqrt(pi))
>>> E(2*X + 1)
1
>>> simplify(std(2*X + 1))
2
>>> m = Normal('X', [1, 2], [[2, 1], [1, 2]])
>>> from sympy.stats.joint_rv import marginal_distribution
>>> pprint(density(m)(y, z))
/ y 1\ /2*y z\ / z \ / y 2*z \
|- - + -|*|--- - -| + |- - + 1|*|- - + --- - 1|
___ \ 2 2/ \ 3 3/ \ 2 / \ 3 3 /
\/ 3 *e
------------------------------------------------------
6*pi
>>> marginal_distribution(m, m[0])(1)
1/(2*sqrt(pi))
References
==========
.. [1] https://en.wikipedia.org/wiki/Normal_distribution
.. [2] http://mathworld.wolfram.com/NormalDistributionFunction.html
"""
if isinstance(mean, (list, MatrixBase)) and\
isinstance(std, (list, MatrixBase)):
from sympy.stats.joint_rv_types import MultivariateNormalDistribution
return multivariate_rv(
MultivariateNormalDistribution, name, mean, std)
return rv(name, NormalDistribution, (mean, std))
#-------------------------------------------------------------------------------
# Pareto distribution ----------------------------------------------------------
class ParetoDistribution(SingleContinuousDistribution):
_argnames = ('xm', 'alpha')
@property
def set(self):
return Interval(self.xm, oo)
@staticmethod
def check(xm, alpha):
_value_check(xm > 0, "Xm must be positive")
_value_check(alpha > 0, "Alpha must be positive")
def pdf(self, x):
xm, alpha = self.xm, self.alpha
return alpha * xm**alpha / x**(alpha + 1)
def sample(self):
return random.paretovariate(self.alpha)
def _cdf(self, x):
xm, alpha = self.xm, self.alpha
return Piecewise(
(S.One - xm**alpha/x**alpha, x>=xm),
(0, True),
)
def _moment_generating_function(self, t):
xm, alpha = self.xm, self.alpha
return alpha * (-xm*t)**alpha * uppergamma(-alpha, -xm*t)
def _characteristic_function(self, t):
xm, alpha = self.xm, self.alpha
return alpha * (-I * xm * t) ** alpha * uppergamma(-alpha, -I * xm * t)
def Pareto(name, xm, alpha):
r"""
Create a continuous random variable with the Pareto distribution.
The density of the Pareto distribution is given by
.. math::
f(x) := \frac{\alpha\,x_m^\alpha}{x^{\alpha+1}}
with :math:`x \in [x_m,\infty]`.
Parameters
==========
xm : Real number, `x_m > 0`, a scale
alpha : Real number, `\alpha > 0`, a shape
Returns
=======
A RandomSymbol.
Examples
========
>>> from sympy.stats import Pareto, density
>>> from sympy import Symbol
>>> xm = Symbol("xm", positive=True)
>>> beta = Symbol("beta", positive=True)
>>> z = Symbol("z")
>>> X = Pareto("x", xm, beta)
>>> density(X)(z)
beta*xm**beta*z**(-beta - 1)
References
==========
.. [1] https://en.wikipedia.org/wiki/Pareto_distribution
.. [2] http://mathworld.wolfram.com/ParetoDistribution.html
"""
return rv(name, ParetoDistribution, (xm, alpha))
#-------------------------------------------------------------------------------
# QuadraticU distribution ------------------------------------------------------
class QuadraticUDistribution(SingleContinuousDistribution):
_argnames = ('a', 'b')
@property
def set(self):
return Interval(self.a, self.b)
def pdf(self, x):
a, b = self.a, self.b
alpha = 12 / (b-a)**3
beta = (a+b) / 2
return Piecewise(
(alpha * (x-beta)**2, And(a<=x, x<=b)),
(S.Zero, True))
def _moment_generating_function(self, t):
a, b = self.a, self.b
return -3 * (exp(a*t) * (4 + (a**2 + 2*a*(-2 + b) + b**2) * t) - exp(b*t) * (4 + (-4*b + (a + b)**2) * t)) / ((a-b)**3 * t**2)
def _characteristic_function(self, t):
def _moment_generating_function(self, t):
a, b = self.a, self.b
return -3*I*(exp(I*a*t*exp(I*b*t)) * (4*I - (-4*b + (a+b)**2)*t)) / ((a-b)**3 * t**2)
def QuadraticU(name, a, b):
r"""
Create a Continuous Random Variable with a U-quadratic distribution.
The density of the U-quadratic distribution is given by
.. math::
f(x) := \alpha (x-\beta)^2
with :math:`x \in [a,b]`.
Parameters
==========
a : Real number
b : Real number, :math:`a < b`
Returns
=======
A RandomSymbol.
Examples
========
>>> from sympy.stats import QuadraticU, density, E, variance
>>> from sympy import Symbol, simplify, factor, pprint
>>> a = Symbol("a", real=True)
>>> b = Symbol("b", real=True)
>>> z = Symbol("z")
>>> X = QuadraticU("x", a, b)
>>> D = density(X)(z)
>>> pprint(D, use_unicode=False)
/ 2
| / a b \
|12*|- - - - + z|
| \ 2 2 /
<----------------- for And(b >= z, a <= z)
| 3
| (-a + b)
|
\ 0 otherwise
References
==========
.. [1] https://en.wikipedia.org/wiki/U-quadratic_distribution
"""
return rv(name, QuadraticUDistribution, (a, b))
#-------------------------------------------------------------------------------
# RaisedCosine distribution ----------------------------------------------------
class RaisedCosineDistribution(SingleContinuousDistribution):
_argnames = ('mu', 's')
@property
def set(self):
return Interval(self.mu - self.s, self.mu + self.s)
@staticmethod
def check(mu, s):
_value_check(s > 0, "s must be positive")
def pdf(self, x):
mu, s = self.mu, self.s
return Piecewise(
((1+cos(pi*(x-mu)/s)) / (2*s), And(mu-s<=x, x<=mu+s)),
(S.Zero, True))
def _characteristic_function(self, t):
mu, s = self.mu, self.s
return Piecewise((exp(-I*pi*mu/s)/2, Eq(t, -pi/s)),
(exp(I*pi*mu/s)/2, Eq(t, pi/s)),
(pi**2*sin(s*t)*exp(I*mu*t) / (s*t*(pi**2 - s**2*t**2)), True))
def _moment_generating_function(self, t):
mu, s = self.mu, self.s
return pi**2 * sinh(s*t) * exp(mu*t) / (s*t*(pi**2 + s**2*t**2))
def RaisedCosine(name, mu, s):
r"""
Create a Continuous Random Variable with a raised cosine distribution.
The density of the raised cosine distribution is given by
.. math::
f(x) := \frac{1}{2s}\left(1+\cos\left(\frac{x-\mu}{s}\pi\right)\right)
with :math:`x \in [\mu-s,\mu+s]`.
Parameters
==========
mu : Real number
s : Real number, `s > 0`
Returns
=======
A RandomSymbol.
Examples
========
>>> from sympy.stats import RaisedCosine, density, E, variance
>>> from sympy import Symbol, simplify, pprint
>>> mu = Symbol("mu", real=True)
>>> s = Symbol("s", positive=True)
>>> z = Symbol("z")
>>> X = RaisedCosine("x", mu, s)
>>> D = density(X)(z)
>>> pprint(D, use_unicode=False)
/ /pi*(-mu + z)\
|cos|------------| + 1
| \ s /
<--------------------- for And(z >= mu - s, z <= mu + s)
| 2*s
|
\ 0 otherwise
References
==========
.. [1] https://en.wikipedia.org/wiki/Raised_cosine_distribution
"""
return rv(name, RaisedCosineDistribution, (mu, s))
#-------------------------------------------------------------------------------
# Rayleigh distribution --------------------------------------------------------
class RayleighDistribution(SingleContinuousDistribution):
_argnames = ('sigma',)
set = Interval(0, oo)
def pdf(self, x):
sigma = self.sigma
return x/sigma**2*exp(-x**2/(2*sigma**2))
def _characteristic_function(self, t):
sigma = self.sigma
return 1 - sigma*t*exp(-sigma**2*t**2/2) * sqrt(pi/2) * (erfi(sigma*t/sqrt(2)) - I)
def _moment_generating_function(self, t):
sigma = self.sigma
return 1 + sigma*t*exp(sigma**2*t**2/2) * sqrt(pi/2) * (erf(sigma*t/sqrt(2)) + 1)
def Rayleigh(name, sigma):
r"""
Create a continuous random variable with a Rayleigh distribution.
The density of the Rayleigh distribution is given by
.. math ::
f(x) := \frac{x}{\sigma^2} e^{-x^2/2\sigma^2}
with :math:`x > 0`.
Parameters
==========
sigma : Real number, `\sigma > 0`
Returns
=======
A RandomSymbol.
Examples
========
>>> from sympy.stats import Rayleigh, density, E, variance
>>> from sympy import Symbol, simplify
>>> sigma = Symbol("sigma", positive=True)
>>> z = Symbol("z")
>>> X = Rayleigh("x", sigma)
>>> density(X)(z)
z*exp(-z**2/(2*sigma**2))/sigma**2
>>> E(X)
sqrt(2)*sqrt(pi)*sigma/2
>>> variance(X)
-pi*sigma**2/2 + 2*sigma**2
References
==========
.. [1] https://en.wikipedia.org/wiki/Rayleigh_distribution
.. [2] http://mathworld.wolfram.com/RayleighDistribution.html
"""
return rv(name, RayleighDistribution, (sigma, ))
#-------------------------------------------------------------------------------
# Shifted Gompertz distribution ------------------------------------------------
class ShiftedGompertzDistribution(SingleContinuousDistribution):
_argnames = ('b', 'eta')
set = Interval(0, oo)
@staticmethod
def check(b, eta):
_value_check(b > 0, "b must be positive")
_value_check(eta > 0, "eta must be positive")
def pdf(self, x):
b, eta = self.b, self.eta
return b*exp(-b*x)*exp(-eta*exp(-b*x))*(1+eta*(1-exp(-b*x)))
def ShiftedGompertz(name, b, eta):
r"""
Create a continuous random variable with a Shifted Gompertz distribution.
The density of the Shifted Gompertz distribution is given by
.. math::
f(x) := b e^{-b x} e^{-\eta \exp(-b x)} \left[1 + \eta(1 - e^(-bx)) \right]
with :math: 'x \in [0, \inf)'.
Parameters
==========
b: Real number, 'b > 0' a scale
eta: Real number, 'eta > 0' a shape
Returns
=======
A RandomSymbol.
Examples
========
>>> from sympy.stats import ShiftedGompertz, density, E, variance
>>> from sympy import Symbol
>>> b = Symbol("b", positive=True)
>>> eta = Symbol("eta", positive=True)
>>> x = Symbol("x")
>>> X = ShiftedGompertz("x", b, eta)
>>> density(X)(x)
b*(eta*(1 - exp(-b*x)) + 1)*exp(-b*x)*exp(-eta*exp(-b*x))
References
==========
.. [1] https://en.wikipedia.org/wiki/Shifted_Gompertz_distribution
"""
return rv(name, ShiftedGompertzDistribution, (b, eta))
#-------------------------------------------------------------------------------
# StudentT distribution --------------------------------------------------------
class StudentTDistribution(SingleContinuousDistribution):
_argnames = ('nu',)
def pdf(self, x):
nu = self.nu
return 1/(sqrt(nu)*beta_fn(S(1)/2, nu/2))*(1 + x**2/nu)**(-(nu + 1)/2)
def _cdf(self, x):
nu = self.nu
return S.Half + x*gamma((nu+1)/2)*hyper((S.Half, (nu+1)/2),
(S(3)/2,), -x**2/nu)/(sqrt(pi*nu)*gamma(nu/2))
def _moment_generating_function(self, t):
raise NotImplementedError('The moment generating function for the Student-T distribution is undefined.')
def StudentT(name, nu):
r"""
Create a continuous random variable with a student's t distribution.
The density of the student's t distribution is given by
.. math::
f(x) := \frac{\Gamma \left(\frac{\nu+1}{2} \right)}
{\sqrt{\nu\pi}\Gamma \left(\frac{\nu}{2} \right)}
\left(1+\frac{x^2}{\nu} \right)^{-\frac{\nu+1}{2}}
Parameters
==========
nu : Real number, `\nu > 0`, the degrees of freedom
Returns
=======
A RandomSymbol.
Examples
========
>>> from sympy.stats import StudentT, density, E, variance, cdf
>>> from sympy import Symbol, simplify, pprint
>>> nu = Symbol("nu", positive=True)
>>> z = Symbol("z")
>>> X = StudentT("x", nu)
>>> D = density(X)(z)
>>> pprint(D, use_unicode=False)
nu 1
- -- - -
2 2
/ 2\
| z |
|1 + --|
\ nu/
-----------------
____ / nu\
\/ nu *B|1/2, --|
\ 2 /
>>> cdf(X)(z)
1/2 + z*gamma(nu/2 + 1/2)*hyper((1/2, nu/2 + 1/2), (3/2,),
-z**2/nu)/(sqrt(pi)*sqrt(nu)*gamma(nu/2))
References
==========
.. [1] https://en.wikipedia.org/wiki/Student_t-distribution
.. [2] http://mathworld.wolfram.com/Studentst-Distribution.html
"""
return rv(name, StudentTDistribution, (nu, ))
#-------------------------------------------------------------------------------
# Trapezoidal distribution ------------------------------------------------------
class TrapezoidalDistribution(SingleContinuousDistribution):
_argnames = ('a', 'b', 'c', 'd')
def pdf(self, x):
a, b, c, d = self.a, self.b, self.c, self.d
return Piecewise(
(2*(x-a) / ((b-a)*(d+c-a-b)), And(a <= x, x < b)),
(2 / (d+c-a-b), And(b <= x, x < c)),
(2*(d-x) / ((d-c)*(d+c-a-b)), And(c <= x, x <= d)),
(S.Zero, True))
def Trapezoidal(name, a, b, c, d):
r"""
Create a continuous random variable with a trapezoidal distribution.
The density of the trapezoidal distribution is given by
.. math::
f(x) := \begin{cases}
0 & \mathrm{for\ } x < a, \\
\frac{2(x-a)}{(b-a)(d+c-a-b)} & \mathrm{for\ } a \le x < b, \\
\frac{2}{d+c-a-b} & \mathrm{for\ } b \le x < c, \\
\frac{2(d-x)}{(d-c)(d+c-a-b)} & \mathrm{for\ } c \le x < d, \\
0 & \mathrm{for\ } d < x.
\end{cases}
Parameters
==========
a : Real number, :math:`a < d`
b : Real number, :math:`a <= b < c`
c : Real number, :math:`b < c <= d`
d : Real number
Returns
=======
A RandomSymbol.
Examples
========
>>> from sympy.stats import Trapezoidal, density, E
>>> from sympy import Symbol, pprint
>>> a = Symbol("a")
>>> b = Symbol("b")
>>> c = Symbol("c")
>>> d = Symbol("d")
>>> z = Symbol("z")
>>> X = Trapezoidal("x", a,b,c,d)
>>> pprint(density(X)(z), use_unicode=False)
/ -2*a + 2*z
|------------------------- for And(a <= z, b > z)
|(-a + b)*(-a - b + c + d)
|
| 2
| -------------- for And(b <= z, c > z)
< -a - b + c + d
|
| 2*d - 2*z
|------------------------- for And(d >= z, c <= z)
|(-c + d)*(-a - b + c + d)
|
\ 0 otherwise
References
==========
.. [1] https://en.wikipedia.org/wiki/Trapezoidal_distribution
"""
return rv(name, TrapezoidalDistribution, (a, b, c, d))
#-------------------------------------------------------------------------------
# Triangular distribution ------------------------------------------------------
class TriangularDistribution(SingleContinuousDistribution):
_argnames = ('a', 'b', 'c')
def pdf(self, x):
a, b, c = self.a, self.b, self.c
return Piecewise(
(2*(x - a)/((b - a)*(c - a)), And(a <= x, x < c)),
(2/(b - a), Eq(x, c)),
(2*(b - x)/((b - a)*(b - c)), And(c < x, x <= b)),
(S.Zero, True))
def _characteristic_function(self, t):
a, b, c = self.a, self.b, self.c
return -2 *((b-c) * exp(I*a*t) - (b-a) * exp(I*c*t) + (c-a) * exp(I*b*t)) / ((b-a)*(c-a)*(b-c)*t**2)
def _moment_generating_function(self, t):
a, b, c = self.a, self.b, self.c
return 2 * ((b - c) * exp(a * t) - (b - a) * exp(c * t) + (c + a) * exp(b * t)) / (
(b - a) * (c - a) * (b - c) * t ** 2)
def Triangular(name, a, b, c):
r"""
Create a continuous random variable with a triangular distribution.
The density of the triangular distribution is given by
.. math::
f(x) := \begin{cases}
0 & \mathrm{for\ } x < a, \\
\frac{2(x-a)}{(b-a)(c-a)} & \mathrm{for\ } a \le x < c, \\
\frac{2}{b-a} & \mathrm{for\ } x = c, \\
\frac{2(b-x)}{(b-a)(b-c)} & \mathrm{for\ } c < x \le b, \\
0 & \mathrm{for\ } b < x.
\end{cases}
Parameters
==========
a : Real number, :math:`a \in \left(-\infty, \infty\right)`
b : Real number, :math:`a < b`
c : Real number, :math:`a \leq c \leq b`
Returns
=======
A RandomSymbol.
Examples
========
>>> from sympy.stats import Triangular, density, E
>>> from sympy import Symbol, pprint
>>> a = Symbol("a")
>>> b = Symbol("b")
>>> c = Symbol("c")
>>> z = Symbol("z")
>>> X = Triangular("x", a,b,c)
>>> pprint(density(X)(z), use_unicode=False)
/ -2*a + 2*z
|----------------- for And(a <= z, c > z)
|(-a + b)*(-a + c)
|
| 2
| ------ for c = z
< -a + b
|
| 2*b - 2*z
|---------------- for And(b >= z, c < z)
|(-a + b)*(b - c)
|
\ 0 otherwise
References
==========
.. [1] https://en.wikipedia.org/wiki/Triangular_distribution
.. [2] http://mathworld.wolfram.com/TriangularDistribution.html
"""
return rv(name, TriangularDistribution, (a, b, c))
#-------------------------------------------------------------------------------
# Uniform distribution ---------------------------------------------------------
class UniformDistribution(SingleContinuousDistribution):
_argnames = ('left', 'right')
def pdf(self, x):
left, right = self.left, self.right
return Piecewise(
(S.One/(right - left), And(left <= x, x <= right)),
(S.Zero, True)
)
def _cdf(self, x):
left, right = self.left, self.right
return Piecewise(
(S.Zero, x < left),
((x - left)/(right - left), x <= right),
(S.One, True)
)
def _characteristic_function(self, t):
left, right = self.left, self.right
return Piecewise(((exp(I*t*right) - exp(I*t*left)) / (I*t*(right - left)), Ne(t, 0)),
(S.One, True))
def _moment_generating_function(self, t):
left, right = self.left, self.right
return Piecewise(((exp(t*right) - exp(t*left)) / (t * (right - left)), Ne(t, 0)),
(S.One, True))
def expectation(self, expr, var, **kwargs):
from sympy import Max, Min
kwargs['evaluate'] = True
result = SingleContinuousDistribution.expectation(self, expr, var, **kwargs)
result = result.subs({Max(self.left, self.right): self.right,
Min(self.left, self.right): self.left})
return result
def sample(self):
return random.uniform(self.left, self.right)
def Uniform(name, left, right):
r"""
Create a continuous random variable with a uniform distribution.
The density of the uniform distribution is given by
.. math::
f(x) := \begin{cases}
\frac{1}{b - a} & \text{for } x \in [a,b] \\
0 & \text{otherwise}
\end{cases}
with :math:`x \in [a,b]`.
Parameters
==========
a : Real number, :math:`-\infty < a` the left boundary
b : Real number, :math:`a < b < \infty` the right boundary
Returns
=======
A RandomSymbol.
Examples
========
>>> from sympy.stats import Uniform, density, cdf, E, variance, skewness
>>> from sympy import Symbol, simplify
>>> a = Symbol("a", negative=True)
>>> b = Symbol("b", positive=True)
>>> z = Symbol("z")
>>> X = Uniform("x", a, b)
>>> density(X)(z)
Piecewise((1/(-a + b), (b >= z) & (a <= z)), (0, True))
>>> cdf(X)(z) # doctest: +SKIP
-a/(-a + b) + z/(-a + b)
>>> simplify(E(X))
a/2 + b/2
>>> simplify(variance(X))
a**2/12 - a*b/6 + b**2/12
References
==========
.. [1] https://en.wikipedia.org/wiki/Uniform_distribution_%28continuous%29
.. [2] http://mathworld.wolfram.com/UniformDistribution.html
"""
return rv(name, UniformDistribution, (left, right))
#-------------------------------------------------------------------------------
# UniformSum distribution ------------------------------------------------------
class UniformSumDistribution(SingleContinuousDistribution):
_argnames = ('n',)
@property
def set(self):
return Interval(0, self.n)
def pdf(self, x):
n = self.n
k = Dummy("k")
return 1/factorial(
n - 1)*Sum((-1)**k*binomial(n, k)*(x - k)**(n - 1), (k, 0, floor(x)))
def _cdf(self, x):
n = self.n
k = Dummy("k")
return Piecewise((S.Zero, x < 0),
(1/factorial(n)*Sum((-1)**k*binomial(n, k)*(x - k)**(n),
(k, 0, floor(x))), x <= n),
(S.One, True))
def _characteristic_function(self, t):
return ((exp(I*t) - 1) / (I*t))**self.n
def _moment_generating_function(self, t):
return ((exp(t) - 1) / t)**self.n
def UniformSum(name, n):
r"""
Create a continuous random variable with an Irwin-Hall distribution.
The probability distribution function depends on a single parameter
`n` which is an integer.
The density of the Irwin-Hall distribution is given by
.. math ::
f(x) := \frac{1}{(n-1)!}\sum_{k=0}^{\left\lfloor x\right\rfloor}(-1)^k
\binom{n}{k}(x-k)^{n-1}
Parameters
==========
n : A positive Integer, `n > 0`
Returns
=======
A RandomSymbol.
Examples
========
>>> from sympy.stats import UniformSum, density, cdf
>>> from sympy import Symbol, pprint
>>> n = Symbol("n", integer=True)
>>> z = Symbol("z")
>>> X = UniformSum("x", n)
>>> D = density(X)(z)
>>> pprint(D, use_unicode=False)
floor(z)
___
\ `
\ k n - 1 /n\
) (-1) *(-k + z) *| |
/ \k/
/__,
k = 0
--------------------------------
(n - 1)!
>>> cdf(X)(z)
Piecewise((0, z < 0), (Sum((-1)**_k*(-_k + z)**n*binomial(n, _k),
(_k, 0, floor(z)))/factorial(n), n >= z), (1, True))
Compute cdf with specific 'x' and 'n' values as follows :
>>> cdf(UniformSum("x", 5), evaluate=False)(2).doit()
9/40
The argument evaluate=False prevents an attempt at evaluation
of the sum for general n, before the argument 2 is passed.
References
==========
.. [1] https://en.wikipedia.org/wiki/Uniform_sum_distribution
.. [2] http://mathworld.wolfram.com/UniformSumDistribution.html
"""
return rv(name, UniformSumDistribution, (n, ))
#-------------------------------------------------------------------------------
# VonMises distribution --------------------------------------------------------
class VonMisesDistribution(SingleContinuousDistribution):
_argnames = ('mu', 'k')
set = Interval(0, 2*pi)
@staticmethod
def check(mu, k):
_value_check(k > 0, "k must be positive")
def pdf(self, x):
mu, k = self.mu, self.k
return exp(k*cos(x-mu)) / (2*pi*besseli(0, k))
def VonMises(name, mu, k):
r"""
Create a Continuous Random Variable with a von Mises distribution.
The density of the von Mises distribution is given by
.. math::
f(x) := \frac{e^{\kappa\cos(x-\mu)}}{2\pi I_0(\kappa)}
with :math:`x \in [0,2\pi]`.
Parameters
==========
mu : Real number, measure of location
k : Real number, measure of concentration
Returns
=======
A RandomSymbol.
Examples
========
>>> from sympy.stats import VonMises, density, E, variance
>>> from sympy import Symbol, simplify, pprint
>>> mu = Symbol("mu")
>>> k = Symbol("k", positive=True)
>>> z = Symbol("z")
>>> X = VonMises("x", mu, k)
>>> D = density(X)(z)
>>> pprint(D, use_unicode=False)
k*cos(mu - z)
e
------------------
2*pi*besseli(0, k)
References
==========
.. [1] https://en.wikipedia.org/wiki/Von_Mises_distribution
.. [2] http://mathworld.wolfram.com/vonMisesDistribution.html
"""
return rv(name, VonMisesDistribution, (mu, k))
#-------------------------------------------------------------------------------
# Weibull distribution ---------------------------------------------------------
class WeibullDistribution(SingleContinuousDistribution):
_argnames = ('alpha', 'beta')
set = Interval(0, oo)
@staticmethod
def check(alpha, beta):
_value_check(alpha > 0, "Alpha must be positive")
_value_check(beta > 0, "Beta must be positive")
def pdf(self, x):
alpha, beta = self.alpha, self.beta
return beta * (x/alpha)**(beta - 1) * exp(-(x/alpha)**beta) / alpha
def sample(self):
return random.weibullvariate(self.alpha, self.beta)
def Weibull(name, alpha, beta):
r"""
Create a continuous random variable with a Weibull distribution.
The density of the Weibull distribution is given by
.. math::
f(x) := \begin{cases}
\frac{k}{\lambda}\left(\frac{x}{\lambda}\right)^{k-1}
e^{-(x/\lambda)^{k}} & x\geq0\\
0 & x<0
\end{cases}
Parameters
==========
lambda : Real number, :math:`\lambda > 0` a scale
k : Real number, `k > 0` a shape
Returns
=======
A RandomSymbol.
Examples
========
>>> from sympy.stats import Weibull, density, E, variance
>>> from sympy import Symbol, simplify
>>> l = Symbol("lambda", positive=True)
>>> k = Symbol("k", positive=True)
>>> z = Symbol("z")
>>> X = Weibull("x", l, k)
>>> density(X)(z)
k*(z/lambda)**(k - 1)*exp(-(z/lambda)**k)/lambda
>>> simplify(E(X))
lambda*gamma(1 + 1/k)
>>> simplify(variance(X))
lambda**2*(-gamma(1 + 1/k)**2 + gamma(1 + 2/k))
References
==========
.. [1] https://en.wikipedia.org/wiki/Weibull_distribution
.. [2] http://mathworld.wolfram.com/WeibullDistribution.html
"""
return rv(name, WeibullDistribution, (alpha, beta))
#-------------------------------------------------------------------------------
# Wigner semicircle distribution -----------------------------------------------
class WignerSemicircleDistribution(SingleContinuousDistribution):
_argnames = ('R',)
@property
def set(self):
return Interval(-self.R, self.R)
def pdf(self, x):
R = self.R
return 2/(pi*R**2)*sqrt(R**2 - x**2)
def _characteristic_function(self, t):
return Piecewise((2 * besselj(1, self.R*t) / (self.R*t), Ne(t, 0)),
(S.One, True))
def _moment_generating_function(self, t):
return Piecewise((2 * besseli(1, self.R*t) / (self.R*t), Ne(t, 0)),
(S.One, True))
def WignerSemicircle(name, R):
r"""
Create a continuous random variable with a Wigner semicircle distribution.
The density of the Wigner semicircle distribution is given by
.. math::
f(x) := \frac2{\pi R^2}\,\sqrt{R^2-x^2}
with :math:`x \in [-R,R]`.
Parameters
==========
R : Real number, `R > 0`, the radius
Returns
=======
A `RandomSymbol`.
Examples
========
>>> from sympy.stats import WignerSemicircle, density, E
>>> from sympy import Symbol, simplify
>>> R = Symbol("R", positive=True)
>>> z = Symbol("z")
>>> X = WignerSemicircle("x", R)
>>> density(X)(z)
2*sqrt(R**2 - z**2)/(pi*R**2)
>>> E(X)
0
References
==========
.. [1] https://en.wikipedia.org/wiki/Wigner_semicircle_distribution
.. [2] http://mathworld.wolfram.com/WignersSemicircleLaw.html
"""
return rv(name, WignerSemicircleDistribution, (R,))
|
051006bcf873c0549fbb1f9440647dba4f5b59fe5b7842775c6fe94f9142f84c
|
"""
Finite Discrete Random Variables - Prebuilt variable types
Contains
========
FiniteRV
DiscreteUniform
Die
Bernoulli
Coin
Binomial
Hypergeometric
Rademacher
"""
from __future__ import print_function, division
from sympy import (S, sympify, Rational, binomial, cacheit, Integer,
Dict, Basic, KroneckerDelta, Dummy)
from sympy.concrete.summations import Sum
from sympy.core.compatibility import as_int, range
from sympy.core.logic import fuzzy_not, fuzzy_and
from sympy.stats.frv import (SingleFinitePSpace, SingleFiniteDistribution)
__all__ = ['FiniteRV', 'DiscreteUniform', 'Die', 'Bernoulli', 'Coin',
'Binomial', 'Hypergeometric']
def rv(name, cls, *args):
density = cls(*args)
return SingleFinitePSpace(name, density).value
class FiniteDistributionHandmade(SingleFiniteDistribution):
@property
def dict(self):
return self.args[0]
def __new__(cls, density):
density = Dict(density)
for k in density.values():
k_sym = sympify(k)
if fuzzy_not(fuzzy_and((k_sym.is_nonnegative, (k_sym - 1).is_nonpositive))):
raise ValueError("Probability at a point must be between 0 and 1.")
sum_sym = sum(density.values())
if sum_sym != 1:
raise ValueError("Total Probability must be equal to 1.")
return Basic.__new__(cls, density)
def FiniteRV(name, density):
"""
Create a Finite Random Variable given a dict representing the density.
Returns a RandomSymbol.
>>> from sympy.stats import FiniteRV, P, E
>>> density = {0: .1, 1: .2, 2: .3, 3: .4}
>>> X = FiniteRV('X', density)
>>> E(X)
2.00000000000000
>>> P(X >= 2)
0.700000000000000
"""
return rv(name, FiniteDistributionHandmade, density)
class DiscreteUniformDistribution(SingleFiniteDistribution):
@property
def p(self):
return Rational(1, len(self.args))
@property
@cacheit
def dict(self):
return dict((k, self.p) for k in self.set)
@property
def set(self):
return self.args
def pdf(self, x):
if x in self.args:
return self.p
else:
return S.Zero
def DiscreteUniform(name, items):
"""
Create a Finite Random Variable representing a uniform distribution over
the input set.
Returns a RandomSymbol.
Examples
========
>>> from sympy.stats import DiscreteUniform, density
>>> from sympy import symbols
>>> X = DiscreteUniform('X', symbols('a b c')) # equally likely over a, b, c
>>> density(X).dict
{a: 1/3, b: 1/3, c: 1/3}
>>> Y = DiscreteUniform('Y', list(range(5))) # distribution over a range
>>> density(Y).dict
{0: 1/5, 1: 1/5, 2: 1/5, 3: 1/5, 4: 1/5}
References
==========
.. [1] https://en.wikipedia.org/wiki/Discrete_uniform_distribution
.. [2] http://mathworld.wolfram.com/DiscreteUniformDistribution.html
"""
return rv(name, DiscreteUniformDistribution, *items)
class DieDistribution(SingleFiniteDistribution):
_argnames = ('sides',)
def __new__(cls, sides):
sides_sym = sympify(sides)
if fuzzy_not(fuzzy_and((sides_sym.is_integer, sides_sym.is_positive))):
raise ValueError("'sides' must be a positive integer.")
else:
return super(DieDistribution, cls).__new__(cls, sides)
@property
@cacheit
def dict(self):
as_int(self.sides) # Check that self.sides can be converted to an integer
return super(DieDistribution, self).dict
@property
def set(self):
return list(map(Integer, list(range(1, self.sides + 1))))
def pdf(self, x):
x = sympify(x)
if x.is_number:
if x.is_Integer and x >= 1 and x <= self.sides:
return Rational(1, self.sides)
return S.Zero
if x.is_Symbol:
i = Dummy('i', integer=True, positive=True)
return Sum(KroneckerDelta(x, i)/self.sides, (i, 1, self.sides))
raise ValueError("'x' expected as an argument of type 'number' or 'symbol', "
"not %s" % (type(x)))
def Die(name, sides=6):
"""
Create a Finite Random Variable representing a fair die.
Returns a RandomSymbol.
Examples
========
>>> from sympy.stats import Die, density
>>> D6 = Die('D6', 6) # Six sided Die
>>> density(D6).dict
{1: 1/6, 2: 1/6, 3: 1/6, 4: 1/6, 5: 1/6, 6: 1/6}
>>> D4 = Die('D4', 4) # Four sided Die
>>> density(D4).dict
{1: 1/4, 2: 1/4, 3: 1/4, 4: 1/4}
"""
return rv(name, DieDistribution, sides)
class BernoulliDistribution(SingleFiniteDistribution):
_argnames = ('p', 'succ', 'fail')
def __new__(cls, *args):
p = args[BernoulliDistribution._argnames.index('p')]
p_sym = sympify(p)
if fuzzy_not(fuzzy_and((p_sym.is_nonnegative, (p_sym - 1).is_nonpositive))):
raise ValueError("p = %s is not in range [0, 1]." % str(p))
else:
return super(BernoulliDistribution, cls).__new__(cls, *args)
@property
@cacheit
def dict(self):
return {self.succ: self.p, self.fail: 1 - self.p}
def Bernoulli(name, p, succ=1, fail=0):
"""
Create a Finite Random Variable representing a Bernoulli process.
Returns a RandomSymbol
Examples
========
>>> from sympy.stats import Bernoulli, density
>>> from sympy import S
>>> X = Bernoulli('X', S(3)/4) # 1-0 Bernoulli variable, probability = 3/4
>>> density(X).dict
{0: 1/4, 1: 3/4}
>>> X = Bernoulli('X', S.Half, 'Heads', 'Tails') # A fair coin toss
>>> density(X).dict
{Heads: 1/2, Tails: 1/2}
References
==========
.. [1] https://en.wikipedia.org/wiki/Bernoulli_distribution
.. [2] http://mathworld.wolfram.com/BernoulliDistribution.html
"""
return rv(name, BernoulliDistribution, p, succ, fail)
def Coin(name, p=S.Half):
"""
Create a Finite Random Variable representing a Coin toss.
Probability p is the chance of gettings "Heads." Half by default
Returns a RandomSymbol.
Examples
========
>>> from sympy.stats import Coin, density
>>> from sympy import Rational
>>> C = Coin('C') # A fair coin toss
>>> density(C).dict
{H: 1/2, T: 1/2}
>>> C2 = Coin('C2', Rational(3, 5)) # An unfair coin
>>> density(C2).dict
{H: 3/5, T: 2/5}
See Also
========
sympy.stats.Binomial
References
==========
.. [1] https://en.wikipedia.org/wiki/Coin_flipping
"""
return rv(name, BernoulliDistribution, p, 'H', 'T')
class BinomialDistribution(SingleFiniteDistribution):
_argnames = ('n', 'p', 'succ', 'fail')
def __new__(cls, *args):
n = args[BinomialDistribution._argnames.index('n')]
p = args[BinomialDistribution._argnames.index('p')]
n_sym = sympify(n)
p_sym = sympify(p)
if fuzzy_not(fuzzy_and((n_sym.is_integer, n_sym.is_nonnegative))):
raise ValueError("'n' must be positive integer. n = %s." % str(n))
elif fuzzy_not(fuzzy_and((p_sym.is_nonnegative, (p_sym - 1).is_nonpositive))):
raise ValueError("'p' must be: 0 <= p <= 1 . p = %s" % str(p))
else:
return super(BinomialDistribution, cls).__new__(cls, *args)
@property
@cacheit
def dict(self):
n, p, succ, fail = self.n, self.p, self.succ, self.fail
n = as_int(n)
return dict((k*succ + (n - k)*fail,
binomial(n, k) * p**k * (1 - p)**(n - k)) for k in range(0, n + 1))
def Binomial(name, n, p, succ=1, fail=0):
"""
Create a Finite Random Variable representing a binomial distribution.
Returns a RandomSymbol.
Examples
========
>>> from sympy.stats import Binomial, density
>>> from sympy import S
>>> X = Binomial('X', 4, S.Half) # Four "coin flips"
>>> density(X).dict
{0: 1/16, 1: 1/4, 2: 3/8, 3: 1/4, 4: 1/16}
References
==========
.. [1] https://en.wikipedia.org/wiki/Binomial_distribution
.. [2] http://mathworld.wolfram.com/BinomialDistribution.html
"""
return rv(name, BinomialDistribution, n, p, succ, fail)
class HypergeometricDistribution(SingleFiniteDistribution):
_argnames = ('N', 'm', 'n')
@property
@cacheit
def dict(self):
N, m, n = self.N, self.m, self.n
N, m, n = list(map(sympify, (N, m, n)))
density = dict((sympify(k),
Rational(binomial(m, k) * binomial(N - m, n - k),
binomial(N, n)))
for k in range(max(0, n + m - N), min(m, n) + 1))
return density
def Hypergeometric(name, N, m, n):
"""
Create a Finite Random Variable representing a hypergeometric distribution.
Returns a RandomSymbol.
Examples
========
>>> from sympy.stats import Hypergeometric, density
>>> from sympy import S
>>> X = Hypergeometric('X', 10, 5, 3) # 10 marbles, 5 white (success), 3 draws
>>> density(X).dict
{0: 1/12, 1: 5/12, 2: 5/12, 3: 1/12}
References
==========
.. [1] https://en.wikipedia.org/wiki/Hypergeometric_distribution
.. [2] http://mathworld.wolfram.com/HypergeometricDistribution.html
"""
return rv(name, HypergeometricDistribution, N, m, n)
class RademacherDistribution(SingleFiniteDistribution):
@property
@cacheit
def dict(self):
return {-1: S.Half, 1: S.Half}
def Rademacher(name):
"""
Create a Finite Random Variable representing a Rademacher distribution.
Return a RandomSymbol.
Examples
========
>>> from sympy.stats import Rademacher, density
>>> X = Rademacher('X')
>>> density(X).dict
{-1: 1/2, 1: 1/2}
See Also
========
sympy.stats.Bernoulli
References
==========
.. [1] https://en.wikipedia.org/wiki/Rademacher_distribution
"""
return rv(name, RademacherDistribution)
|
feade15ba68882d0242ecaf122c95b5fdda8904ae216d2038a8cd6e3feadf549
|
from sympy import (sympify, S, pi, sqrt, exp, Lambda, Indexed, Gt,
IndexedBase)
from sympy.matrices import ImmutableMatrix
from sympy.matrices.expressions.determinant import det
from sympy.stats.joint_rv import (JointDistribution, JointPSpace,
JointDistributionHandmade, MarginalDistribution)
from sympy.stats.rv import _value_check, random_symbols
# __all__ = ['MultivariateNormal',
# 'MultivariateLaplace',
# 'MultivariateT',
# 'NormalGamma'
# ]
def multivariate_rv(cls, sym, *args):
args = list(map(sympify, args))
dist = cls(*args)
args = dist.args
dist.check(*args)
return JointPSpace(sym, dist).value
def JointRV(symbol, pdf, _set=None):
"""
Create a Joint Random Variable where each of its component is conitinuous,
given the following:
-- a symbol
-- a PDF in terms of indexed symbols of the symbol given
as the first argument
NOTE: As of now, the set for each component for a `JointRV` is
equal to the set of all integers, which can not be changed.
Returns a RandomSymbol.
Examples
========
>>> from sympy import symbols, exp, pi, Indexed, S
>>> from sympy.stats import density
>>> from sympy.stats.joint_rv_types import JointRV
>>> x1, x2 = (Indexed('x', i) for i in (1, 2))
>>> pdf = exp(-x1**2/2 + x1 - x2**2/2 - S(1)/2)/(2*pi)
>>> N1 = JointRV('x', pdf) #Multivariate Normal distribution
>>> density(N1)(1, 2)
exp(-2)/(2*pi)
"""
#TODO: Add support for sets provided by the user
symbol = sympify(symbol)
syms = list(i for i in pdf.free_symbols if isinstance(i, Indexed)
and i.base == IndexedBase(symbol))
syms.sort(key = lambda index: index.args[1])
_set = S.Reals**len(syms)
pdf = Lambda(syms, pdf)
dist = JointDistributionHandmade(pdf, _set)
jrv = JointPSpace(symbol, dist).value
rvs = random_symbols(pdf)
if len(rvs) != 0:
dist = MarginalDistribution(dist, (jrv,))
return JointPSpace(symbol, dist).value
return jrv
#-------------------------------------------------------------------------------
# Multivariate Normal distribution ---------------------------------------------------------
class MultivariateNormalDistribution(JointDistribution):
_argnames = ['mu', 'sigma']
is_Continuous=True
@property
def set(self):
k = len(self.mu)
return S.Reals**k
def check(self, mu, sigma):
_value_check(len(mu) == len(sigma.col(0)),
"Size of the mean vector and covariance matrix are incorrect.")
#check if covariance matrix is positive definite or not.
_value_check(all([Gt(i, 0) != False for i in sigma.eigenvals().keys()]),
"The covariance matrix must be positive definite. ")
def pdf(self, *args):
mu, sigma = self.mu, self.sigma
k = len(mu)
args = ImmutableMatrix(args)
x = args - mu
return S(1)/sqrt((2*pi)**(k)*det(sigma))*exp(
-S(1)/2*x.transpose()*(sigma.inv()*\
x))[0]
def marginal_distribution(self, indices, sym):
sym = ImmutableMatrix([Indexed(sym, i) for i in indices])
_mu, _sigma = self.mu, self.sigma
k = len(self.mu)
for i in range(k):
if i not in indices:
_mu = _mu.row_del(i)
_sigma = _sigma.col_del(i)
_sigma = _sigma.row_del(i)
return Lambda(sym, S(1)/sqrt((2*pi)**(len(_mu))*det(_sigma))*exp(
-S(1)/2*(_mu - sym).transpose()*(_sigma.inv()*\
(_mu - sym)))[0])
#-------------------------------------------------------------------------------
# Multivariate Laplace distribution ---------------------------------------------------------
class MultivariateLaplaceDistribution(JointDistribution):
_argnames = ['mu', 'sigma']
is_Continuous=True
@property
def set(self):
k = len(self.mu)
return S.Reals**k
def check(self, mu, sigma):
_value_check(len(mu) == len(sigma.col(0)),
"Size of the mean vector and covariance matrix are incorrect.")
#check if covariance matrix is positive definite or not.
_value_check(all([Gt(i, 0) != False for i in sigma.eigenvals().keys()]),
"The covariance matrix must be positive definite. ")
def pdf(self, *args):
from sympy.functions.special.bessel import besselk
mu, sigma = self.mu, self.sigma
mu_T = mu.transpose()
k = S(len(mu))
sigma_inv = sigma.inv()
args = ImmutableMatrix(args)
args_T = args.transpose()
x = (mu_T*sigma_inv*mu)[0]
y = (args_T*sigma_inv*args)[0]
v = 1 - k/2
return S(2)/((2*pi)**(S(k)/2)*sqrt(det(sigma)))\
*(y/(2 + x))**(S(v)/2)*besselk(v, sqrt((2 + x)*(y)))\
*exp((args_T*sigma_inv*mu)[0])
#-------------------------------------------------------------------------------
# Multivariate StudentT distribution ---------------------------------------------------------
class MultivariateTDistribution(JointDistribution):
_argnames = ['mu', 'shape_mat', 'dof']
is_Continuous=True
@property
def set(self):
k = len(self.mu)
return S.Reals**k
def check(self, mu, sigma, v):
_value_check(len(mu) == len(sigma.col(0)),
"Size of the location vector and shape matrix are incorrect.")
#check if covariance matrix is positive definite or not.
_value_check(all([Gt(i, 0) != False for i in sigma.eigenvals().keys()]),
"The shape matrix must be positive definite. ")
def pdf(self, *args):
from sympy.functions.special.gamma_functions import gamma
mu, sigma = self.mu, self.shape_mat
v = S(self.dof)
k = S(len(mu))
sigma_inv = sigma.inv()
args = ImmutableMatrix(args)
x = args - mu
return gamma((k + v)/2)/(gamma(v/2)*(v*pi)**(k/2)*sqrt(det(sigma)))\
*(1 + 1/v*(x.transpose()*sigma_inv*x)[0])**((-v - k)/2)
def MultivariateT(syms, mu, sigma, v):
"""
Creates a joint random variable with multivariate T-distribution.
Parameters
==========
syms: list/tuple/set of symbols for identifying each component
mu: A list/tuple/set consisting of k means,represents a k
dimensional location vector
sigma: The shape matrix for the distribution
Returns
=======
A random symbol
"""
return multivariate_rv(MultivariateTDistribution, syms, mu, sigma, v)
#-------------------------------------------------------------------------------
# Multivariate Normal Gamma distribution ---------------------------------------------------------
class NormalGammaDistribution(JointDistribution):
_argnames = ['mu', 'lamda', 'alpha', 'beta']
is_Continuous=True
def check(self, mu, lamda, alpha, beta):
_value_check(mu.is_real, "Location must be real.")
_value_check(lamda > 0, "Lambda must be positive")
_value_check(alpha > 0, "alpha must be positive")
_value_check(beta > 0, "beta must be positive")
@property
def set(self):
from sympy.sets.sets import Interval
return S.Reals*Interval(0, S.Infinity)
def pdf(self, x, tau):
from sympy.functions.special.gamma_functions import gamma
beta, alpha, lamda = self.beta, self.alpha, self.lamda
mu = self.mu
return beta**alpha*sqrt(lamda)/(gamma(alpha)*sqrt(2*pi))*\
tau**(alpha - S(1)/2)*exp(-1*beta*tau)*\
exp(-1*(lamda*tau*(x - mu)**2)/S(2))
def marginal_distribution(self, indices, *sym):
from sympy.functions.special.gamma_functions import gamma
if len(indices) == 2:
return self.pdf(*sym)
if indices[0] == 0:
#For marginal over `x`, return non-standardized Student-T's
#distribution
x = sym[0]
v, mu, sigma = self.alpha - S(1)/2, self.mu, \
S(self.beta)/(self.lamda * self.alpha)
return Lambda(sym, gamma((v + 1)/2)/(gamma(v/2)*sqrt(pi*v)*sigma)*\
(1 + 1/v*((x - mu)/sigma)**2)**((-v -1)/2))
#For marginal over `tau`, return Gamma distribution as per construction
from sympy.stats.crv_types import GammaDistribution
return Lambda(sym, GammaDistribution(self.alpha, self.beta)(sym[0]))
def NormalGamma(syms, mu, lamda, alpha, beta):
"""
Creates a bivariate joint random variable with multivariate Normal gamma
distribution.
Parameters
==========
syms: list/tuple/set of two symbols for identifying each component
mu: A real number, as the mean of the normal distribution
alpha: a positive integer
beta: a positive integer
lamda: a positive integer
Returns
=======
A random symbol
"""
return multivariate_rv(NormalGammaDistribution, syms, mu, lamda, alpha, beta)
|
5b8ce347016e1af1fbe6ca831824f4f160eb912d9edfe2979795105254fcd90f
|
"""Tools for arithmetic error propagation."""
from __future__ import print_function, division
from itertools import repeat, combinations
from sympy import S, Symbol, Add, Mul, simplify, Pow, exp
from sympy.stats.symbolic_probability import RandomSymbol, Variance, Covariance
_arg0_or_var = lambda var: var.args[0] if len(var.args) > 0 else var
def variance_prop(expr, consts=(), include_covar=False):
r"""Symbolically propagates variance (`\sigma^2`) for expressions.
This is computed as as seen in [1]_.
Parameters
==========
expr : Expr
A sympy expression to compute the variance for.
consts : sequence of Symbols, optional
Represents symbols that are known constants in the expr,
and thus have zero variance. All symbols not in consts are
assumed to be variant.
include_covar : bool, optional
Flag for whether or not to include covariances, default=False.
Returns
=======
var_expr : Expr
An expression for the total variance of the expr.
The variance for the original symbols (e.g. x) are represented
via instance of the Variance symbol (e.g. Variance(x)).
Examples
========
>>> from sympy import symbols, exp
>>> from sympy.stats.error_prop import variance_prop
>>> x, y = symbols('x y')
>>> variance_prop(x + y)
Variance(x) + Variance(y)
>>> variance_prop(x * y)
x**2*Variance(y) + y**2*Variance(x)
>>> variance_prop(exp(2*x))
4*exp(4*x)*Variance(x)
References
==========
.. [1] https://en.wikipedia.org/wiki/Propagation_of_uncertainty
"""
args = expr.args
if len(args) == 0:
if expr in consts:
return S(0)
elif isinstance(expr, RandomSymbol):
return Variance(expr).doit()
elif isinstance(expr, Symbol):
return Variance(RandomSymbol(expr)).doit()
else:
return S(0)
nargs = len(args)
var_args = list(map(variance_prop, args, repeat(consts, nargs),
repeat(include_covar, nargs)))
if isinstance(expr, Add):
var_expr = Add(*var_args)
if include_covar:
terms = [2 * Covariance(_arg0_or_var(x), _arg0_or_var(y)).doit() \
for x, y in combinations(var_args, 2)]
var_expr += Add(*terms)
elif isinstance(expr, Mul):
terms = [v/a**2 for a, v in zip(args, var_args)]
var_expr = simplify(expr**2 * Add(*terms))
if include_covar:
terms = [2*Covariance(_arg0_or_var(x), _arg0_or_var(y)).doit()/(a*b) \
for (a, b), (x, y) in zip(combinations(args, 2),
combinations(var_args, 2))]
var_expr += Add(*terms)
elif isinstance(expr, Pow):
b = args[1]
v = var_args[0] * (expr * b / args[0])**2
var_expr = simplify(v)
elif isinstance(expr, exp):
var_expr = simplify(var_args[0] * expr**2)
else:
# unknown how to proceed, return variance of whole expr.
var_expr = Variance(expr)
return var_expr
|
a17a3d1ca65c463b1ee0993e576e83746d4ec16671dbef0e69580bf94a0ccd5a
|
from __future__ import print_function, division
from sympy import (factorial, exp, S, sympify, And, I, zeta, polylog, log, beta, hyper, binomial,
Piecewise, floor)
from sympy.stats import density
from sympy.stats.drv import SingleDiscreteDistribution, SingleDiscretePSpace
from sympy.stats.joint_rv import JointPSpace, CompoundDistribution
from sympy.stats.rv import _value_check, RandomSymbol
import random
__all__ = ['Geometric', 'Logarithmic', 'NegativeBinomial', 'Poisson', 'YuleSimon', 'Zeta']
def rv(symbol, cls, *args):
args = list(map(sympify, args))
dist = cls(*args)
dist.check(*args)
pspace = SingleDiscretePSpace(symbol, dist)
if any(isinstance(arg, RandomSymbol) for arg in args):
pspace = JointPSpace(symbol, CompoundDistribution(dist))
return pspace.value
#-------------------------------------------------------------------------------
# Geometric distribution ------------------------------------------------------------
class GeometricDistribution(SingleDiscreteDistribution):
_argnames = ('p',)
set = S.Naturals
@staticmethod
def check(p):
_value_check(And(0 < p, p <= 1), "p must be between 0 and 1")
def pdf(self, k):
return (1 - self.p)**(k - 1) * self.p
def _characteristic_function(self, t):
p = self.p
return p * exp(I*t) / (1 - (1 - p)*exp(I*t))
def _moment_generating_function(self, t):
p = self.p
return p * exp(t) / (1 - (1 - p) * exp(t))
def Geometric(name, p):
r"""
Create a discrete random variable with a Geometric distribution.
The density of the Geometric distribution is given by
.. math::
f(k) := p (1 - p)^{k - 1}
Parameters
==========
p: A probability between 0 and 1
Returns
=======
A RandomSymbol.
Examples
========
>>> from sympy.stats import Geometric, density, E, variance
>>> from sympy import Symbol, S
>>> p = S.One / 5
>>> z = Symbol("z")
>>> X = Geometric("x", p)
>>> density(X)(z)
(4/5)**(z - 1)/5
>>> E(X)
5
>>> variance(X)
20
References
==========
.. [1] https://en.wikipedia.org/wiki/Geometric_distribution
.. [2] http://mathworld.wolfram.com/GeometricDistribution.html
"""
return rv(name, GeometricDistribution, p)
#-------------------------------------------------------------------------------
# Logarithmic distribution ------------------------------------------------------------
class LogarithmicDistribution(SingleDiscreteDistribution):
_argnames = ('p',)
set = S.Naturals
@staticmethod
def check(p):
_value_check(And(p > 0, p < 1), "p should be between 0 and 1")
def pdf(self, k):
p = self.p
return (-1) * p**k / (k * log(1 - p))
def _characteristic_function(self, t):
p = self.p
return log(1 - p * exp(I*t)) / log(1 - p)
def _moment_generating_function(self, t):
p = self.p
return log(1 - p * exp(t)) / log(1 - p)
def sample(self):
### TODO
raise NotImplementedError("Sampling of %s is not implemented" % density(self))
def Logarithmic(name, p):
r"""
Create a discrete random variable with a Logarithmic distribution.
The density of the Logarithmic distribution is given by
.. math::
f(k) := \frac{-p^k}{k \ln{(1 - p)}}
Parameters
==========
p: A value between 0 and 1
Returns
=======
A RandomSymbol.
Examples
========
>>> from sympy.stats import Logarithmic, density, E, variance
>>> from sympy import Symbol, S
>>> p = S.One / 5
>>> z = Symbol("z")
>>> X = Logarithmic("x", p)
>>> density(X)(z)
-5**(-z)/(z*log(4/5))
>>> E(X)
-1/(-4*log(5) + 8*log(2))
>>> variance(X)
-1/((-4*log(5) + 8*log(2))*(-2*log(5) + 4*log(2))) + 1/(-64*log(2)*log(5) + 64*log(2)**2 + 16*log(5)**2) - 10/(-32*log(5) + 64*log(2))
References
==========
.. [1] https://en.wikipedia.org/wiki/Logarithmic_distribution
.. [2] http://mathworld.wolfram.com/LogarithmicDistribution.html
"""
return rv(name, LogarithmicDistribution, p)
#-------------------------------------------------------------------------------
# Negative binomial distribution ------------------------------------------------------------
class NegativeBinomialDistribution(SingleDiscreteDistribution):
_argnames = ('r', 'p')
set = S.Naturals0
@staticmethod
def check(r, p):
_value_check(r > 0, 'r should be positive')
_value_check(And(p > 0, p < 1), 'p should be between 0 and 1')
def pdf(self, k):
r = self.r
p = self.p
return binomial(k + r - 1, k) * (1 - p)**r * p**k
def _characteristic_function(self, t):
r = self.r
p = self.p
return ((1 - p) / (1 - p * exp(I*t)))**r
def _moment_generating_function(self, t):
r = self.r
p = self.p
return ((1 - p) / (1 - p * exp(t)))**r
def sample(self):
### TODO
raise NotImplementedError("Sampling of %s is not implemented" % density(self))
def NegativeBinomial(name, r, p):
r"""
Create a discrete random variable with a Negative Binomial distribution.
The density of the Negative Binomial distribution is given by
.. math::
f(k) := \binom{k + r - 1}{k} (1 - p)^r p^k
Parameters
==========
r: A positive value
p: A value between 0 and 1
Returns
=======
A RandomSymbol.
Examples
========
>>> from sympy.stats import NegativeBinomial, density, E, variance
>>> from sympy import Symbol, S
>>> r = 5
>>> p = S.One / 5
>>> z = Symbol("z")
>>> X = NegativeBinomial("x", r, p)
>>> density(X)(z)
1024*5**(-z)*binomial(z + 4, z)/3125
>>> E(X)
5/4
>>> variance(X)
25/16
References
==========
.. [1] https://en.wikipedia.org/wiki/Negative_binomial_distribution
.. [2] http://mathworld.wolfram.com/NegativeBinomialDistribution.html
"""
return rv(name, NegativeBinomialDistribution, r, p)
#-------------------------------------------------------------------------------
# Poisson distribution ------------------------------------------------------------
class PoissonDistribution(SingleDiscreteDistribution):
_argnames = ('lamda',)
set = S.Naturals0
@staticmethod
def check(lamda):
_value_check(lamda > 0, "Lambda must be positive")
def pdf(self, k):
return self.lamda**k / factorial(k) * exp(-self.lamda)
def sample(self):
def search(x, y, u):
while x < y:
mid = (x + y)//2
if u <= self.cdf(mid):
y = mid
else:
x = mid + 1
return x
u = random.uniform(0, 1)
if u <= self.cdf(S.Zero):
return S.Zero
n = S.One
while True:
if u > self.cdf(2*n):
n *= 2
else:
return search(n, 2*n, u)
def _characteristic_function(self, t):
return exp(self.lamda * (exp(I*t) - 1))
def _moment_generating_function(self, t):
return exp(self.lamda * (exp(t) - 1))
def Poisson(name, lamda):
r"""
Create a discrete random variable with a Poisson distribution.
The density of the Poisson distribution is given by
.. math::
f(k) := \frac{\lambda^{k} e^{- \lambda}}{k!}
Parameters
==========
lamda: Positive number, a rate
Returns
=======
A RandomSymbol.
Examples
========
>>> from sympy.stats import Poisson, density, E, variance
>>> from sympy import Symbol, simplify
>>> rate = Symbol("lambda", positive=True)
>>> z = Symbol("z")
>>> X = Poisson("x", rate)
>>> density(X)(z)
lambda**z*exp(-lambda)/factorial(z)
>>> E(X)
lambda
>>> simplify(variance(X))
lambda
References
==========
.. [1] https://en.wikipedia.org/wiki/Poisson_distribution
.. [2] http://mathworld.wolfram.com/PoissonDistribution.html
"""
return rv(name, PoissonDistribution, lamda)
#-------------------------------------------------------------------------------
# Yule-Simon distribution ------------------------------------------------------------
class YuleSimonDistribution(SingleDiscreteDistribution):
_argnames = ('rho',)
set = S.Naturals
@staticmethod
def check(rho):
_value_check(rho > 0, 'rho should be positive')
def pdf(self, k):
rho = self.rho
return rho * beta(k, rho + 1)
def _cdf(self, x):
return Piecewise((1 - floor(x) * beta(floor(x), self.rho + 1), x >= 1), (0, True))
def _characteristic_function(self, t):
rho = self.rho
return rho * hyper((1, 1), (rho + 2,), exp(I*t)) * exp(I*t) / (rho + 1)
def _moment_generating_function(self, t):
rho = self.rho
return rho * hyper((1, 1), (rho + 2,), exp(t)) * exp(t) / (rho + 1)
def sample(self):
### TODO
raise NotImplementedError("Sampling of %s is not implemented" % density(self))
def YuleSimon(name, rho):
r"""
Create a discrete random variable with a Yule-Simon distribution.
The density of the Yule-Simon distribution is given by
.. math::
f(k) := \rho B(k, \rho + 1)
Parameters
==========
rho: A positive value
Returns
=======
A RandomSymbol.
Examples
========
>>> from sympy.stats import YuleSimon, density, E, variance
>>> from sympy import Symbol, simplify
>>> p = 5
>>> z = Symbol("z")
>>> X = YuleSimon("x", p)
>>> density(X)(z)
5*beta(z, 6)
>>> simplify(E(X))
5/4
>>> simplify(variance(X))
25/48
References
==========
.. [1] https://en.wikipedia.org/wiki/Yule%E2%80%93Simon_distribution
"""
return rv(name, YuleSimonDistribution, rho)
#-------------------------------------------------------------------------------
# Zeta distribution ------------------------------------------------------------
class ZetaDistribution(SingleDiscreteDistribution):
_argnames = ('s',)
set = S.Naturals
@staticmethod
def check(s):
_value_check(s > 1, 's should be greater than 1')
def pdf(self, k):
s = self.s
return 1 / (k**s * zeta(s))
def _characteristic_function(self, t):
return polylog(self.s, exp(I*t)) / zeta(self.s)
def _moment_generating_function(self, t):
return polylog(self.s, exp(t)) / zeta(self.s)
def sample(self):
### TODO
raise NotImplementedError("Sampling of %s is not implemented" % density(self))
def Zeta(name, s):
r"""
Create a discrete random variable with a Zeta distribution.
The density of the Zeta distribution is given by
.. math::
f(k) := \frac{1}{k^s \zeta{(s)}}
Parameters
==========
s: A value greater than 1
Returns
=======
A RandomSymbol.
Examples
========
>>> from sympy.stats import Zeta, density, E, variance
>>> from sympy import Symbol
>>> s = 5
>>> z = Symbol("z")
>>> X = Zeta("x", s)
>>> density(X)(z)
1/(z**5*zeta(5))
>>> E(X)
pi**4/(90*zeta(5))
>>> variance(X)
-pi**8/(8100*zeta(5)**2) + zeta(3)/zeta(5)
References
==========
.. [1] https://en.wikipedia.org/wiki/Zeta_distribution
"""
return rv(name, ZetaDistribution, s)
|
ad59ad7aa640a79a058f962205e19beb82fd430c16ac1378d7f5580a763e3bc5
|
"""
Main Random Variables Module
Defines abstract random variable type.
Contains interfaces for probability space object (PSpace) as well as standard
operators, P, E, sample, density, where
See Also
========
sympy.stats.crv
sympy.stats.frv
sympy.stats.rv_interface
"""
from __future__ import print_function, division
from sympy import (Basic, S, Expr, Symbol, Tuple, And, Add, Eq, lambdify,
Equality, Lambda, sympify, Dummy, Ne, KroneckerDelta,
DiracDelta, Mul)
from sympy.abc import x
from sympy.core.compatibility import string_types
from sympy.core.relational import Relational
from sympy.logic.boolalg import Boolean
from sympy.sets.sets import FiniteSet, ProductSet, Intersection
from sympy.solvers.solveset import solveset
class RandomDomain(Basic):
"""
Represents a set of variables and the values which they can take
See Also
========
sympy.stats.crv.ContinuousDomain
sympy.stats.frv.FiniteDomain
"""
is_ProductDomain = False
is_Finite = False
is_Continuous = False
is_Discrete = False
def __new__(cls, symbols, *args):
symbols = FiniteSet(*symbols)
return Basic.__new__(cls, symbols, *args)
@property
def symbols(self):
return self.args[0]
@property
def set(self):
return self.args[1]
def __contains__(self, other):
raise NotImplementedError()
def compute_expectation(self, expr):
raise NotImplementedError()
class SingleDomain(RandomDomain):
"""
A single variable and its domain
See Also
========
sympy.stats.crv.SingleContinuousDomain
sympy.stats.frv.SingleFiniteDomain
"""
def __new__(cls, symbol, set):
assert symbol.is_Symbol
return Basic.__new__(cls, symbol, set)
@property
def symbol(self):
return self.args[0]
@property
def symbols(self):
return FiniteSet(self.symbol)
def __contains__(self, other):
if len(other) != 1:
return False
sym, val = tuple(other)[0]
return self.symbol == sym and val in self.set
class ConditionalDomain(RandomDomain):
"""
A RandomDomain with an attached condition
See Also
========
sympy.stats.crv.ConditionalContinuousDomain
sympy.stats.frv.ConditionalFiniteDomain
"""
def __new__(cls, fulldomain, condition):
condition = condition.xreplace(dict((rs, rs.symbol)
for rs in random_symbols(condition)))
return Basic.__new__(cls, fulldomain, condition)
@property
def symbols(self):
return self.fulldomain.symbols
@property
def fulldomain(self):
return self.args[0]
@property
def condition(self):
return self.args[1]
@property
def set(self):
raise NotImplementedError("Set of Conditional Domain not Implemented")
def as_boolean(self):
return And(self.fulldomain.as_boolean(), self.condition)
class PSpace(Basic):
"""
A Probability Space
Probability Spaces encode processes that equal different values
probabilistically. These underly Random Symbols which occur in SymPy
expressions and contain the mechanics to evaluate statistical statements.
See Also
========
sympy.stats.crv.ContinuousPSpace
sympy.stats.frv.FinitePSpace
"""
is_Finite = None
is_Continuous = None
is_Discrete = None
is_real = None
@property
def domain(self):
return self.args[0]
@property
def density(self):
return self.args[1]
@property
def values(self):
return frozenset(RandomSymbol(sym, self) for sym in self.symbols)
@property
def symbols(self):
return self.domain.symbols
def where(self, condition):
raise NotImplementedError()
def compute_density(self, expr):
raise NotImplementedError()
def sample(self):
raise NotImplementedError()
def probability(self, condition):
raise NotImplementedError()
def compute_expectation(self, expr):
raise NotImplementedError()
class SinglePSpace(PSpace):
"""
Represents the probabilities of a set of random events that can be
attributed to a single variable/symbol.
"""
def __new__(cls, s, distribution):
if isinstance(s, string_types):
s = Symbol(s)
if not isinstance(s, Symbol):
raise TypeError("s should have been string or Symbol")
return Basic.__new__(cls, s, distribution)
@property
def value(self):
return RandomSymbol(self.symbol, self)
@property
def symbol(self):
return self.args[0]
@property
def distribution(self):
return self.args[1]
@property
def pdf(self):
return self.distribution.pdf(self.symbol)
class RandomSymbol(Expr):
"""
Random Symbols represent ProbabilitySpaces in SymPy Expressions
In principle they can take on any value that their symbol can take on
within the associated PSpace with probability determined by the PSpace
Density.
Random Symbols contain pspace and symbol properties.
The pspace property points to the represented Probability Space
The symbol is a standard SymPy Symbol that is used in that probability space
for example in defining a density.
You can form normal SymPy expressions using RandomSymbols and operate on
those expressions with the Functions
E - Expectation of a random expression
P - Probability of a condition
density - Probability Density of an expression
given - A new random expression (with new random symbols) given a condition
An object of the RandomSymbol type should almost never be created by the
user. They tend to be created instead by the PSpace class's value method.
Traditionally a user doesn't even do this but instead calls one of the
convenience functions Normal, Exponential, Coin, Die, FiniteRV, etc....
"""
def __new__(cls, symbol, pspace=None):
from sympy.stats.joint_rv import JointRandomSymbol
if pspace is None:
# Allow single arg, representing pspace == PSpace()
pspace = PSpace()
if not isinstance(symbol, Symbol):
raise TypeError("symbol should be of type Symbol")
if not isinstance(pspace, PSpace):
raise TypeError("pspace variable should be of type PSpace")
if cls == JointRandomSymbol and isinstance(pspace, SinglePSpace):
cls = RandomSymbol
return Basic.__new__(cls, symbol, pspace)
is_finite = True
is_symbol = True
is_Atom = True
_diff_wrt = True
pspace = property(lambda self: self.args[1])
symbol = property(lambda self: self.args[0])
name = property(lambda self: self.symbol.name)
def _eval_is_positive(self):
return self.symbol.is_positive
def _eval_is_integer(self):
return self.symbol.is_integer
def _eval_is_real(self):
return self.symbol.is_real or self.pspace.is_real
@property
def is_commutative(self):
return self.symbol.is_commutative
def _hashable_content(self):
return self.pspace, self.symbol
@property
def free_symbols(self):
return {self}
class ProductPSpace(PSpace):
"""
Abstract class for representing probability spaces with multiple random
variables.
See Also
========
sympy.stats.rv.IndependentProductPSpace
sympy.stats.joint_rv.JointPSpace
"""
pass
class IndependentProductPSpace(ProductPSpace):
"""
A probability space resulting from the merger of two independent probability
spaces.
Often created using the function, pspace
"""
def __new__(cls, *spaces):
rs_space_dict = {}
for space in spaces:
for value in space.values:
rs_space_dict[value] = space
symbols = FiniteSet(*[val.symbol for val in rs_space_dict.keys()])
# Overlapping symbols
from sympy.stats.joint_rv import MarginalDistribution, CompoundDistribution
if len(symbols) < sum(len(space.symbols) for space in spaces if not
isinstance(space.distribution, (
CompoundDistribution, MarginalDistribution))):
raise ValueError("Overlapping Random Variables")
if all(space.is_Finite for space in spaces):
from sympy.stats.frv import ProductFinitePSpace
cls = ProductFinitePSpace
obj = Basic.__new__(cls, *FiniteSet(*spaces))
return obj
@property
def pdf(self):
p = Mul(*[space.pdf for space in self.spaces])
return p.subs(dict((rv, rv.symbol) for rv in self.values))
@property
def rs_space_dict(self):
d = {}
for space in self.spaces:
for value in space.values:
d[value] = space
return d
@property
def symbols(self):
return FiniteSet(*[val.symbol for val in self.rs_space_dict.keys()])
@property
def spaces(self):
return FiniteSet(*self.args)
@property
def values(self):
return sumsets(space.values for space in self.spaces)
def compute_expectation(self, expr, rvs=None, evaluate=False, **kwargs):
rvs = rvs or self.values
rvs = frozenset(rvs)
for space in self.spaces:
expr = space.compute_expectation(expr, rvs & space.values, evaluate=False, **kwargs)
if evaluate and hasattr(expr, 'doit'):
return expr.doit(**kwargs)
return expr
@property
def domain(self):
return ProductDomain(*[space.domain for space in self.spaces])
@property
def density(self):
raise NotImplementedError("Density not available for ProductSpaces")
def sample(self):
return dict([(k, v) for space in self.spaces
for k, v in space.sample().items()])
def probability(self, condition, **kwargs):
cond_inv = False
if isinstance(condition, Ne):
condition = Eq(condition.args[0], condition.args[1])
cond_inv = True
expr = condition.lhs - condition.rhs
rvs = random_symbols(expr)
z = Dummy('z', real=True, Finite=True)
dens = self.compute_density(expr)
if any([pspace(rv).is_Continuous for rv in rvs]):
from sympy.stats.crv import (ContinuousDistributionHandmade,
SingleContinuousPSpace)
if expr in self.values:
# Marginalize all other random symbols out of the density
randomsymbols = tuple(set(self.values) - frozenset([expr]))
symbols = tuple(rs.symbol for rs in randomsymbols)
pdf = self.domain.integrate(self.pdf, symbols, **kwargs)
return Lambda(expr.symbol, pdf)
dens = ContinuousDistributionHandmade(dens)
space = SingleContinuousPSpace(z, dens)
result = space.probability(condition.__class__(space.value, 0))
else:
from sympy.stats.drv import (DiscreteDistributionHandmade,
SingleDiscretePSpace)
dens = DiscreteDistributionHandmade(dens)
space = SingleDiscretePSpace(z, dens)
result = space.probability(condition.__class__(space.value, 0))
return result if not cond_inv else S.One - result
def compute_density(self, expr, **kwargs):
z = Dummy('z', real=True, finite=True)
rvs = random_symbols(expr)
if any(pspace(rv).is_Continuous for rv in rvs):
expr = self.compute_expectation(DiracDelta(expr - z),
**kwargs)
else:
expr = self.compute_expectation(KroneckerDelta(expr, z),
**kwargs)
return Lambda(z, expr)
def compute_cdf(self, expr, **kwargs):
raise ValueError("CDF not well defined on multivariate expressions")
def conditional_space(self, condition, normalize=True, **kwargs):
rvs = random_symbols(condition)
condition = condition.xreplace(dict((rv, rv.symbol) for rv in self.values))
if any([pspace(rv).is_Continuous for rv in rvs]):
from sympy.stats.crv import (ConditionalContinuousDomain,
ContinuousPSpace)
space = ContinuousPSpace
domain = ConditionalContinuousDomain(self.domain, condition)
elif any([pspace(rv).is_Discrete for rv in rvs]):
from sympy.stats.drv import (ConditionalDiscreteDomain,
DiscretePSpace)
space = DiscretePSpace
domain = ConditionalDiscreteDomain(self.domain, condition)
elif all([pspace(rv).is_Finite for rv in rvs]):
from sympy.stats.frv import FinitePSpace
return FinitePSpace.conditional_space(self, condition)
if normalize:
replacement = {rv: Dummy(str(rv)) for rv in self.symbols}
norm = domain.compute_expectation(self.pdf, **kwargs)
pdf = self.pdf / norm.xreplace(replacement)
density = Lambda(domain.symbols, pdf)
return space(domain, density)
class ProductDomain(RandomDomain):
"""
A domain resulting from the merger of two independent domains
See Also
========
sympy.stats.crv.ProductContinuousDomain
sympy.stats.frv.ProductFiniteDomain
"""
is_ProductDomain = True
def __new__(cls, *domains):
# Flatten any product of products
domains2 = []
for domain in domains:
if not domain.is_ProductDomain:
domains2.append(domain)
else:
domains2.extend(domain.domains)
domains2 = FiniteSet(*domains2)
if all(domain.is_Finite for domain in domains2):
from sympy.stats.frv import ProductFiniteDomain
cls = ProductFiniteDomain
if all(domain.is_Continuous for domain in domains2):
from sympy.stats.crv import ProductContinuousDomain
cls = ProductContinuousDomain
if all(domain.is_Discrete for domain in domains2):
from sympy.stats.drv import ProductDiscreteDomain
cls = ProductDiscreteDomain
return Basic.__new__(cls, *domains2)
@property
def sym_domain_dict(self):
return dict((symbol, domain) for domain in self.domains
for symbol in domain.symbols)
@property
def symbols(self):
return FiniteSet(*[sym for domain in self.domains
for sym in domain.symbols])
@property
def domains(self):
return self.args
@property
def set(self):
return ProductSet(domain.set for domain in self.domains)
def __contains__(self, other):
# Split event into each subdomain
for domain in self.domains:
# Collect the parts of this event which associate to this domain
elem = frozenset([item for item in other
if sympify(domain.symbols.contains(item[0]))
is S.true])
# Test this sub-event
if elem not in domain:
return False
# All subevents passed
return True
def as_boolean(self):
return And(*[domain.as_boolean() for domain in self.domains])
def random_symbols(expr):
"""
Returns all RandomSymbols within a SymPy Expression.
"""
try:
return list(expr.atoms(RandomSymbol))
except AttributeError:
return []
def pspace(expr):
"""
Returns the underlying Probability Space of a random expression.
For internal use.
Examples
========
>>> from sympy.stats import pspace, Normal
>>> from sympy.stats.rv import IndependentProductPSpace
>>> X = Normal('X', 0, 1)
>>> pspace(2*X + 1) == X.pspace
True
"""
expr = sympify(expr)
if isinstance(expr, RandomSymbol) and expr.pspace != None:
return expr.pspace
rvs = random_symbols(expr)
if not rvs:
raise ValueError("Expression containing Random Variable expected, not %s" % (expr))
# If only one space present
if all(rv.pspace == rvs[0].pspace for rv in rvs):
return rvs[0].pspace
# Otherwise make a product space
return IndependentProductPSpace(*[rv.pspace for rv in rvs])
def sumsets(sets):
"""
Union of sets
"""
return frozenset().union(*sets)
def rs_swap(a, b):
"""
Build a dictionary to swap RandomSymbols based on their underlying symbol.
i.e.
if ``X = ('x', pspace1)``
and ``Y = ('x', pspace2)``
then ``X`` and ``Y`` match and the key, value pair
``{X:Y}`` will appear in the result
Inputs: collections a and b of random variables which share common symbols
Output: dict mapping RVs in a to RVs in b
"""
d = {}
for rsa in a:
d[rsa] = [rsb for rsb in b if rsa.symbol == rsb.symbol][0]
return d
def given(expr, condition=None, **kwargs):
r""" Conditional Random Expression
From a random expression and a condition on that expression creates a new
probability space from the condition and returns the same expression on that
conditional probability space.
Examples
========
>>> from sympy.stats import given, density, Die
>>> X = Die('X', 6)
>>> Y = given(X, X > 3)
>>> density(Y).dict
{4: 1/3, 5: 1/3, 6: 1/3}
Following convention, if the condition is a random symbol then that symbol
is considered fixed.
>>> from sympy.stats import Normal
>>> from sympy import pprint
>>> from sympy.abc import z
>>> X = Normal('X', 0, 1)
>>> Y = Normal('Y', 0, 1)
>>> pprint(density(X + Y, Y)(z), use_unicode=False)
2
-(-Y + z)
-----------
___ 2
\/ 2 *e
------------------
____
2*\/ pi
"""
if not random_symbols(condition) or pspace_independent(expr, condition):
return expr
if isinstance(condition, RandomSymbol):
condition = Eq(condition, condition.symbol)
condsymbols = random_symbols(condition)
if (isinstance(condition, Equality) and len(condsymbols) == 1 and
not isinstance(pspace(expr).domain, ConditionalDomain)):
rv = tuple(condsymbols)[0]
results = solveset(condition, rv)
if isinstance(results, Intersection) and S.Reals in results.args:
results = list(results.args[1])
sums = 0
for res in results:
temp = expr.subs(rv, res)
if temp == True:
return True
if temp != False:
sums += expr.subs(rv, res)
if sums == 0:
return False
return sums
# Get full probability space of both the expression and the condition
fullspace = pspace(Tuple(expr, condition))
# Build new space given the condition
space = fullspace.conditional_space(condition, **kwargs)
# Dictionary to swap out RandomSymbols in expr with new RandomSymbols
# That point to the new conditional space
swapdict = rs_swap(fullspace.values, space.values)
# Swap random variables in the expression
expr = expr.xreplace(swapdict)
return expr
def expectation(expr, condition=None, numsamples=None, evaluate=True, **kwargs):
"""
Returns the expected value of a random expression
Parameters
==========
expr : Expr containing RandomSymbols
The expression of which you want to compute the expectation value
given : Expr containing RandomSymbols
A conditional expression. E(X, X>0) is expectation of X given X > 0
numsamples : int
Enables sampling and approximates the expectation with this many samples
evalf : Bool (defaults to True)
If sampling return a number rather than a complex expression
evaluate : Bool (defaults to True)
In case of continuous systems return unevaluated integral
Examples
========
>>> from sympy.stats import E, Die
>>> X = Die('X', 6)
>>> E(X)
7/2
>>> E(2*X + 1)
8
>>> E(X, X > 3) # Expectation of X given that it is above 3
5
"""
if not random_symbols(expr): # expr isn't random?
return expr
if numsamples: # Computing by monte carlo sampling?
return sampling_E(expr, condition, numsamples=numsamples)
# Create new expr and recompute E
if condition is not None: # If there is a condition
return expectation(given(expr, condition), evaluate=evaluate)
# A few known statements for efficiency
if expr.is_Add: # We know that E is Linear
return Add(*[expectation(arg, evaluate=evaluate)
for arg in expr.args])
# Otherwise case is simple, pass work off to the ProbabilitySpace
result = pspace(expr).compute_expectation(expr, evaluate=evaluate, **kwargs)
if evaluate and hasattr(result, 'doit'):
return result.doit(**kwargs)
else:
return result
def probability(condition, given_condition=None, numsamples=None,
evaluate=True, **kwargs):
"""
Probability that a condition is true, optionally given a second condition
Parameters
==========
condition : Combination of Relationals containing RandomSymbols
The condition of which you want to compute the probability
given_condition : Combination of Relationals containing RandomSymbols
A conditional expression. P(X > 1, X > 0) is expectation of X > 1
given X > 0
numsamples : int
Enables sampling and approximates the probability with this many samples
evaluate : Bool (defaults to True)
In case of continuous systems return unevaluated integral
Examples
========
>>> from sympy.stats import P, Die
>>> from sympy import Eq
>>> X, Y = Die('X', 6), Die('Y', 6)
>>> P(X > 3)
1/2
>>> P(Eq(X, 5), X > 2) # Probability that X == 5 given that X > 2
1/4
>>> P(X > Y)
5/12
"""
condition = sympify(condition)
given_condition = sympify(given_condition)
if given_condition is not None and \
not isinstance(given_condition, (Relational, Boolean)):
raise ValueError("%s is not a relational or combination of relationals"
% (given_condition))
if given_condition == False:
return S.Zero
if not isinstance(condition, (Relational, Boolean)):
raise ValueError("%s is not a relational or combination of relationals"
% (condition))
if condition is S.true:
return S.One
if condition is S.false:
return S.Zero
if numsamples:
return sampling_P(condition, given_condition, numsamples=numsamples,
**kwargs)
if given_condition is not None: # If there is a condition
# Recompute on new conditional expr
return probability(given(condition, given_condition, **kwargs), **kwargs)
# Otherwise pass work off to the ProbabilitySpace
result = pspace(condition).probability(condition, **kwargs)
if evaluate and hasattr(result, 'doit'):
return result.doit()
else:
return result
class Density(Basic):
expr = property(lambda self: self.args[0])
@property
def condition(self):
if len(self.args) > 1:
return self.args[1]
else:
return None
def doit(self, evaluate=True, **kwargs):
from sympy.stats.joint_rv import JointPSpace
expr, condition = self.expr, self.condition
if condition is not None:
# Recompute on new conditional expr
expr = given(expr, condition, **kwargs)
if isinstance(expr, RandomSymbol) and \
isinstance(expr.pspace, JointPSpace):
return expr.pspace.distribution
if not random_symbols(expr):
return Lambda(x, DiracDelta(x - expr))
if (isinstance(expr, RandomSymbol) and
hasattr(expr.pspace, 'distribution') and
isinstance(pspace(expr), (SinglePSpace))):
return expr.pspace.distribution
result = pspace(expr).compute_density(expr, **kwargs)
if evaluate and hasattr(result, 'doit'):
return result.doit()
else:
return result
def density(expr, condition=None, evaluate=True, numsamples=None, **kwargs):
"""
Probability density of a random expression, optionally given a second
condition.
This density will take on different forms for different types of
probability spaces. Discrete variables produce Dicts. Continuous
variables produce Lambdas.
Parameters
==========
expr : Expr containing RandomSymbols
The expression of which you want to compute the density value
condition : Relational containing RandomSymbols
A conditional expression. density(X > 1, X > 0) is density of X > 1
given X > 0
numsamples : int
Enables sampling and approximates the density with this many samples
Examples
========
>>> from sympy.stats import density, Die, Normal
>>> from sympy import Symbol
>>> x = Symbol('x')
>>> D = Die('D', 6)
>>> X = Normal(x, 0, 1)
>>> density(D).dict
{1: 1/6, 2: 1/6, 3: 1/6, 4: 1/6, 5: 1/6, 6: 1/6}
>>> density(2*D).dict
{2: 1/6, 4: 1/6, 6: 1/6, 8: 1/6, 10: 1/6, 12: 1/6}
>>> density(X)(x)
sqrt(2)*exp(-x**2/2)/(2*sqrt(pi))
"""
if numsamples:
return sampling_density(expr, condition, numsamples=numsamples,
**kwargs)
return Density(expr, condition).doit(evaluate=evaluate, **kwargs)
def cdf(expr, condition=None, evaluate=True, **kwargs):
"""
Cumulative Distribution Function of a random expression.
optionally given a second condition
This density will take on different forms for different types of
probability spaces.
Discrete variables produce Dicts.
Continuous variables produce Lambdas.
Examples
========
>>> from sympy.stats import density, Die, Normal, cdf
>>> D = Die('D', 6)
>>> X = Normal('X', 0, 1)
>>> density(D).dict
{1: 1/6, 2: 1/6, 3: 1/6, 4: 1/6, 5: 1/6, 6: 1/6}
>>> cdf(D)
{1: 1/6, 2: 1/3, 3: 1/2, 4: 2/3, 5: 5/6, 6: 1}
>>> cdf(3*D, D > 2)
{9: 1/4, 12: 1/2, 15: 3/4, 18: 1}
>>> cdf(X)
Lambda(_z, erf(sqrt(2)*_z/2)/2 + 1/2)
"""
if condition is not None: # If there is a condition
# Recompute on new conditional expr
return cdf(given(expr, condition, **kwargs), **kwargs)
# Otherwise pass work off to the ProbabilitySpace
result = pspace(expr).compute_cdf(expr, **kwargs)
if evaluate and hasattr(result, 'doit'):
return result.doit()
else:
return result
def characteristic_function(expr, condition=None, evaluate=True, **kwargs):
"""
Characteristic function of a random expression, optionally given a second condition
Returns a Lambda
Examples
========
>>> from sympy.stats import Normal, DiscreteUniform, Poisson, characteristic_function
>>> X = Normal('X', 0, 1)
>>> characteristic_function(X)
Lambda(_t, exp(-_t**2/2))
>>> Y = DiscreteUniform('Y', [1, 2, 7])
>>> characteristic_function(Y)
Lambda(_t, exp(7*_t*I)/3 + exp(2*_t*I)/3 + exp(_t*I)/3)
>>> Z = Poisson('Z', 2)
>>> characteristic_function(Z)
Lambda(_t, exp(2*exp(_t*I) - 2))
"""
if condition is not None:
return characteristic_function(given(expr, condition, **kwargs), **kwargs)
result = pspace(expr).compute_characteristic_function(expr, **kwargs)
if evaluate and hasattr(result, 'doit'):
return result.doit()
else:
return result
def moment_generating_function(expr, condition=None, evaluate=True, **kwargs):
if condition is not None:
return moment_generating_function(given(expr, condition, **kwargs), **kwargs)
result = pspace(expr).compute_moment_generating_function(expr, **kwargs)
if evaluate and hasattr(result, 'doit'):
return result.doit()
else:
return result
def where(condition, given_condition=None, **kwargs):
"""
Returns the domain where a condition is True.
Examples
========
>>> from sympy.stats import where, Die, Normal
>>> from sympy import symbols, And
>>> D1, D2 = Die('a', 6), Die('b', 6)
>>> a, b = D1.symbol, D2.symbol
>>> X = Normal('x', 0, 1)
>>> where(X**2<1)
Domain: (-1 < x) & (x < 1)
>>> where(X**2<1).set
Interval.open(-1, 1)
>>> where(And(D1<=D2 , D2<3))
Domain: (Eq(a, 1) & Eq(b, 1)) | (Eq(a, 1) & Eq(b, 2)) | (Eq(a, 2) & Eq(b, 2))
"""
if given_condition is not None: # If there is a condition
# Recompute on new conditional expr
return where(given(condition, given_condition, **kwargs), **kwargs)
# Otherwise pass work off to the ProbabilitySpace
return pspace(condition).where(condition, **kwargs)
def sample(expr, condition=None, **kwargs):
"""
A realization of the random expression
Examples
========
>>> from sympy.stats import Die, sample
>>> X, Y, Z = Die('X', 6), Die('Y', 6), Die('Z', 6)
>>> die_roll = sample(X + Y + Z) # A random realization of three dice
"""
return next(sample_iter(expr, condition, numsamples=1))
def sample_iter(expr, condition=None, numsamples=S.Infinity, **kwargs):
"""
Returns an iterator of realizations from the expression given a condition
Parameters
==========
expr: Expr
Random expression to be realized
condition: Expr, optional
A conditional expression
numsamples: integer, optional
Length of the iterator (defaults to infinity)
Examples
========
>>> from sympy.stats import Normal, sample_iter
>>> X = Normal('X', 0, 1)
>>> expr = X*X + 3
>>> iterator = sample_iter(expr, numsamples=3)
>>> list(iterator) # doctest: +SKIP
[12, 4, 7]
See Also
========
Sample
sampling_P
sampling_E
sample_iter_lambdify
sample_iter_subs
"""
# lambdify is much faster but not as robust
try:
return sample_iter_lambdify(expr, condition, numsamples, **kwargs)
# use subs when lambdify fails
except TypeError:
return sample_iter_subs(expr, condition, numsamples, **kwargs)
def sample_iter_lambdify(expr, condition=None, numsamples=S.Infinity, **kwargs):
"""
See sample_iter
Uses lambdify for computation. This is fast but does not always work.
"""
if condition:
ps = pspace(Tuple(expr, condition))
else:
ps = pspace(expr)
rvs = list(ps.values)
fn = lambdify(rvs, expr, **kwargs)
if condition:
given_fn = lambdify(rvs, condition, **kwargs)
# Check that lambdify can handle the expression
# Some operations like Sum can prove difficult
try:
d = ps.sample() # a dictionary that maps RVs to values
args = [d[rv] for rv in rvs]
fn(*args)
if condition:
given_fn(*args)
except Exception:
raise TypeError("Expr/condition too complex for lambdify")
def return_generator():
count = 0
while count < numsamples:
d = ps.sample() # a dictionary that maps RVs to values
args = [d[rv] for rv in rvs]
if condition: # Check that these values satisfy the condition
gd = given_fn(*args)
if gd != True and gd != False:
raise ValueError(
"Conditions must not contain free symbols")
if not gd: # If the values don't satisfy then try again
continue
yield fn(*args)
count += 1
return return_generator()
def sample_iter_subs(expr, condition=None, numsamples=S.Infinity, **kwargs):
"""
See sample_iter
Uses subs for computation. This is slow but almost always works.
"""
if condition is not None:
ps = pspace(Tuple(expr, condition))
else:
ps = pspace(expr)
count = 0
while count < numsamples:
d = ps.sample() # a dictionary that maps RVs to values
if condition is not None: # Check that these values satisfy the condition
gd = condition.xreplace(d)
if gd != True and gd != False:
raise ValueError("Conditions must not contain free symbols")
if not gd: # If the values don't satisfy then try again
continue
yield expr.xreplace(d)
count += 1
def sampling_P(condition, given_condition=None, numsamples=1,
evalf=True, **kwargs):
"""
Sampling version of P
See Also
========
P
sampling_E
sampling_density
"""
count_true = 0
count_false = 0
samples = sample_iter(condition, given_condition,
numsamples=numsamples, **kwargs)
for sample in samples:
if sample != True and sample != False:
raise ValueError("Conditions must not contain free symbols")
if sample:
count_true += 1
else:
count_false += 1
result = S(count_true) / numsamples
if evalf:
return result.evalf()
else:
return result
def sampling_E(expr, given_condition=None, numsamples=1,
evalf=True, **kwargs):
"""
Sampling version of E
See Also
========
P
sampling_P
sampling_density
"""
samples = sample_iter(expr, given_condition,
numsamples=numsamples, **kwargs)
result = Add(*list(samples)) / numsamples
if evalf:
return result.evalf()
else:
return result
def sampling_density(expr, given_condition=None, numsamples=1, **kwargs):
"""
Sampling version of density
See Also
========
density
sampling_P
sampling_E
"""
results = {}
for result in sample_iter(expr, given_condition,
numsamples=numsamples, **kwargs):
results[result] = results.get(result, 0) + 1
return results
def dependent(a, b):
"""
Dependence of two random expressions
Two expressions are independent if knowledge of one does not change
computations on the other.
Examples
========
>>> from sympy.stats import Normal, dependent, given
>>> from sympy import Tuple, Eq
>>> X, Y = Normal('X', 0, 1), Normal('Y', 0, 1)
>>> dependent(X, Y)
False
>>> dependent(2*X + Y, -Y)
True
>>> X, Y = given(Tuple(X, Y), Eq(X + Y, 3))
>>> dependent(X, Y)
True
See Also
========
independent
"""
if pspace_independent(a, b):
return False
z = Symbol('z', real=True)
# Dependent if density is unchanged when one is given information about
# the other
return (density(a, Eq(b, z)) != density(a) or
density(b, Eq(a, z)) != density(b))
def independent(a, b):
"""
Independence of two random expressions
Two expressions are independent if knowledge of one does not change
computations on the other.
Examples
========
>>> from sympy.stats import Normal, independent, given
>>> from sympy import Tuple, Eq
>>> X, Y = Normal('X', 0, 1), Normal('Y', 0, 1)
>>> independent(X, Y)
True
>>> independent(2*X + Y, -Y)
False
>>> X, Y = given(Tuple(X, Y), Eq(X + Y, 3))
>>> independent(X, Y)
False
See Also
========
dependent
"""
return not dependent(a, b)
def pspace_independent(a, b):
"""
Tests for independence between a and b by checking if their PSpaces have
overlapping symbols. This is a sufficient but not necessary condition for
independence and is intended to be used internally.
Notes
=====
pspace_independent(a, b) implies independent(a, b)
independent(a, b) does not imply pspace_independent(a, b)
"""
a_symbols = set(pspace(b).symbols)
b_symbols = set(pspace(a).symbols)
if len(set(random_symbols(a)).intersection(random_symbols(b))) != 0:
return False
if len(a_symbols.intersection(b_symbols)) == 0:
return True
return None
def rv_subs(expr, symbols=None):
"""
Given a random expression replace all random variables with their symbols.
If symbols keyword is given restrict the swap to only the symbols listed.
"""
if symbols is None:
symbols = random_symbols(expr)
if not symbols:
return expr
swapdict = {rv: rv.symbol for rv in symbols}
return expr.xreplace(swapdict)
class NamedArgsMixin(object):
_argnames = ()
def __getattr__(self, attr):
try:
return self.args[self._argnames.index(attr)]
except ValueError:
raise AttributeError("'%s' object has no attribute '%s'" % (
type(self).__name__, attr))
def _value_check(condition, message):
"""
Check a condition on input value.
Raises ValueError with message if condition is not True
"""
if condition == False:
raise ValueError(message)
|
0a93d25b1d2798681d3bdb686793d7852def1ab64c8f4981c29a274add120d05
|
"""
Joint Random Variables Module
See Also
========
sympy.stats.rv
sympy.stats.frv
sympy.stats.crv
sympy.stats.drv
"""
from __future__ import print_function, division
# __all__ = ['marginal_distribution']
from sympy import (Basic, Lambda, sympify, Indexed, Symbol, ProductSet, S,
Dummy)
from sympy.concrete.summations import Sum, summation
from sympy.core.compatibility import string_types
from sympy.core.containers import Tuple
from sympy.integrals.integrals import Integral, integrate
from sympy.matrices import ImmutableMatrix
from sympy.stats.crv import (ContinuousDistribution,
SingleContinuousDistribution, SingleContinuousPSpace)
from sympy.stats.drv import (DiscreteDistribution,
SingleDiscreteDistribution, SingleDiscretePSpace)
from sympy.stats.rv import (ProductPSpace, NamedArgsMixin,
ProductDomain, RandomSymbol, random_symbols, SingleDomain)
from sympy.utilities.misc import filldedent
class JointPSpace(ProductPSpace):
"""
Represents a joint probability space. Represented using symbols for
each component and a distribution.
"""
def __new__(cls, sym, dist):
if isinstance(dist, SingleContinuousDistribution):
return SingleContinuousPSpace(sym, dist)
if isinstance(dist, SingleDiscreteDistribution):
return SingleDiscretePSpace(sym, dist)
if isinstance(sym, string_types):
sym = Symbol(sym)
if not isinstance(sym, Symbol):
raise TypeError("s should have been string or Symbol")
return Basic.__new__(cls, sym, dist)
@property
def set(self):
return self.domain.set
@property
def symbol(self):
return self.args[0]
@property
def distribution(self):
return self.args[1]
@property
def value(self):
return JointRandomSymbol(self.symbol, self)
@property
def component_count(self):
_set = self.distribution.set
return len(_set.args) if isinstance(_set, ProductSet) else 1
@property
def pdf(self):
sym = [Indexed(self.symbol, i) for i in range(self.component_count)]
return self.distribution(*sym)
@property
def domain(self):
rvs = random_symbols(self.distribution)
if len(rvs) == 0:
return SingleDomain(self.symbol, self.set)
return ProductDomain(*[rv.pspace.domain for rv in rvs])
def component_domain(self, index):
return self.set.args[index]
@property
def symbols(self):
return self.domain.symbols
def marginal_distribution(self, *indices):
count = self.component_count
orig = [Indexed(self.symbol, i) for i in range(count)]
all_syms = [Symbol(str(i)) for i in orig]
replace_dict = dict(zip(all_syms, orig))
sym = [Symbol(str(Indexed(self.symbol, i))) for i in indices]
limits = list([i,] for i in all_syms if i not in sym)
index = 0
for i in range(count):
if i not in indices:
limits[index].append(self.distribution.set.args[i])
limits[index] = tuple(limits[index])
index += 1
limits = tuple(limits)
if self.distribution.is_Continuous:
f = Lambda(sym, integrate(self.distribution(*all_syms), limits))
elif self.distribution.is_Discrete:
f = Lambda(sym, summation(self.distribution(all_syms), limits))
return f.xreplace(replace_dict)
def compute_expectation(self, expr, rvs=None, evaluate=False, **kwargs):
syms = tuple(self.value[i] for i in range(self.component_count))
rvs = rvs or syms
if not any([i in rvs for i in syms]):
return expr
expr = expr*self.pdf
for rv in rvs:
if isinstance(rv, Indexed):
expr = expr.xreplace({rv: Indexed(str(rv.base), rv.args[1])})
elif isinstance(rv, RandomSymbol):
expr = expr.xreplace({rv: rv.symbol})
if self.value in random_symbols(expr):
raise NotImplementedError(filldedent('''
Expectations of expression with unindexed joint random symbols
cannot be calculated yet.'''))
limits = tuple((Indexed(str(rv.base),rv.args[1]),
self.distribution.set.args[rv.args[1]]) for rv in syms)
return Integral(expr, *limits)
def where(self, condition):
raise NotImplementedError()
def compute_density(self, expr):
raise NotImplementedError()
def sample(self):
raise NotImplementedError()
def probability(self, condition):
raise NotImplementedError()
class JointDistribution(Basic, NamedArgsMixin):
"""
Represented by the random variables part of the joint distribution.
Contains methods for PDF, CDF, sampling, marginal densities, etc.
"""
_argnames = ('pdf', )
def __new__(cls, *args):
args = list(map(sympify, args))
for i in range(len(args)):
if isinstance(args[i], list):
args[i] = ImmutableMatrix(args[i])
return Basic.__new__(cls, *args)
@property
def domain(self):
return ProductDomain(self.symbols)
@property
def pdf(self, *args):
return self.density.args[1]
def cdf(self, other):
assert isinstance(other, dict)
rvs = other.keys()
_set = self.domain.set
expr = self.pdf(tuple(i.args[0] for i in self.symbols))
for i in range(len(other)):
if rvs[i].is_Continuous:
density = Integral(expr, (rvs[i], _set[i].inf,
other[rvs[i]]))
elif rvs[i].is_Discrete:
density = Sum(expr, (rvs[i], _set[i].inf,
other[rvs[i]]))
return density
def __call__(self, *args):
return self.pdf(*args)
class JointRandomSymbol(RandomSymbol):
"""
Representation of random symbols with joint probability distributions
to allow indexing."
"""
def __getitem__(self, key):
from sympy.stats.joint_rv import JointPSpace
if isinstance(self.pspace, JointPSpace):
if self.pspace.component_count <= key:
raise ValueError("Index keys for %s can only up to %s." %
(self.name, self.pspace.component_count - 1))
return Indexed(self, key)
class JointDistributionHandmade(JointDistribution, NamedArgsMixin):
_argnames = ('pdf',)
is_Continuous = True
@property
def set(self):
return self.args[1]
def marginal_distribution(rv, *indices):
"""
Marginal distribution function of a joint random variable.
Parameters
==========
rv: A random variable with a joint probability distribution.
indices: component indices or the indexed random symbol
for whom the joint distribution is to be calculated
Returns
=======
A Lambda expression n `sym`.
Examples
========
>>> from sympy.stats.crv_types import Normal
>>> from sympy.stats.joint_rv import marginal_distribution
>>> m = Normal('X', [1, 2], [[2, 1], [1, 2]])
>>> marginal_distribution(m, m[0])(1)
1/(2*sqrt(pi))
"""
indices = list(indices)
for i in range(len(indices)):
if isinstance(indices[i], Indexed):
indices[i] = indices[i].args[1]
prob_space = rv.pspace
if indices == ():
raise ValueError(
"At least one component for marginal density is needed.")
if hasattr(prob_space.distribution, 'marginal_distribution'):
return prob_space.distribution.marginal_distribution(indices, rv.symbol)
return prob_space.marginal_distribution(*indices)
class CompoundDistribution(Basic, NamedArgsMixin):
"""
Represents a compound probability distribution.
Constructed using a single probability distribution with a parameter
distributed according to some given distribution.
"""
def __new__(cls, dist):
if not isinstance(dist, (ContinuousDistribution, DiscreteDistribution)):
raise ValueError(filldedent('''CompoundDistribution can only be
initialized from ContinuousDistribution or DiscreteDistribution
'''))
_args = dist.args
if not any([isinstance(i, RandomSymbol) for i in _args]):
return dist
return Basic.__new__(cls, dist)
@property
def latent_distributions(self):
return random_symbols(self.args[0])
def pdf(self, *x):
dist = self.args[0]
z = Dummy('z')
if isinstance(dist, ContinuousDistribution):
rv = SingleContinuousPSpace(z, dist).value
elif isinstance(dist, DiscreteDistribution):
rv = SingleDiscretePSpace(z, dist).value
return MarginalDistribution(self, (rv,)).pdf(*x)
def set(self):
return self.args[0].set
def __call__(self, *args):
return self.pdf(*args)
class MarginalDistribution(Basic):
"""
Represents the marginal distribution of a joint probability space.
Initialised using a probability distribution and random variables(or
their indexed components) which should be a part of the resultant
distribution.
"""
def __new__(cls, dist, rvs):
if not all([isinstance(rv, (Indexed, RandomSymbol))] for rv in rvs):
raise ValueError(filldedent('''Marginal distribution can be
intitialised only in terms of random variables or indexed random
variables'''))
rvs = Tuple.fromiter(rv for rv in rvs)
if not isinstance(dist, JointDistribution) and len(random_symbols(dist)) == 0:
return dist
return Basic.__new__(cls, dist, rvs)
def check(self):
pass
@property
def set(self):
rvs = [i for i in random_symbols(self.args[1])]
marginalise_out = [i for i in random_symbols(self.args[1]) \
if i not in self.args[1]]
for i in rvs:
if i in marginalise_out:
rvs.remove(i)
return ProductSet((i.pspace.set for i in rvs))
@property
def symbols(self):
rvs = self.args[1]
return set([rv.pspace.symbol for rv in rvs])
def pdf(self, *x):
expr, rvs = self.args[0], self.args[1]
marginalise_out = [i for i in random_symbols(expr) if i not in self.args[1]]
syms = [i.pspace.symbol for i in self.args[1]]
for i in expr.atoms(Indexed):
if isinstance(i, Indexed) and isinstance(i.base, RandomSymbol)\
and i not in rvs:
marginalise_out.append(i)
if isinstance(expr, CompoundDistribution):
syms = Dummy('x', real=True)
expr = expr.args[0].pdf(syms)
elif isinstance(expr, JointDistribution):
count = len(expr.domain.args)
x = Dummy('x', real=True, finite=True)
syms = [Indexed(x, i) for i in count]
expr = expression.pdf(syms)
return Lambda(syms, self.compute_pdf(expr, marginalise_out))(*x)
def compute_pdf(self, expr, rvs):
for rv in rvs:
lpdf = 1
if isinstance(rv, RandomSymbol):
lpdf = rv.pspace.pdf
expr = self.marginalise_out(expr*lpdf, rv)
return expr
def marginalise_out(self, expr, rv):
from sympy.concrete.summations import Sum
if isinstance(rv, RandomSymbol):
dom = rv.pspace.set
elif isinstance(rv, Indexed):
dom = rv.base.component_domain(
rv.pspace.component_domain(rv.args[1]))
expr = expr.xreplace({rv: rv.pspace.symbol})
if rv.pspace.is_Continuous:
#TODO: Modify to support integration
#for all kinds of sets.
expr = Integral(expr, (rv.pspace.symbol, dom))
elif rv.pspace.is_Discrete:
#incorporate this into `Sum`/`summation`
if dom in (S.Integers, S.Naturals, S.Naturals0):
dom = (dom.inf, dom.sup)
expr = Sum(expr, (rv.pspace.symbol, dom))
return expr
def __call__(self, *args):
return self.pdf(*args)
|
32a77c10991d329db1cf2c664d7ff7c69f09ab88a371845c01df713e27c6b1ce
|
from __future__ import print_function, division
from sympy import (Basic, sympify, symbols, Dummy, Lambda, summation,
Piecewise, S, cacheit, Sum, exp, I, Ne, Eq, poly,
series, factorial, And)
from sympy.polys.polyerrors import PolynomialError
from sympy.solvers.solveset import solveset
from sympy.stats.crv import reduce_rational_inequalities_wrap
from sympy.stats.rv import (NamedArgsMixin, SinglePSpace, SingleDomain,
random_symbols, PSpace, ConditionalDomain, RandomDomain,
ProductDomain)
from sympy.stats.symbolic_probability import Probability
from sympy.functions.elementary.integers import floor
from sympy.sets.fancysets import Range, FiniteSet
from sympy.sets.sets import Union
from sympy.sets.contains import Contains
from sympy.utilities import filldedent
import random
class DiscreteDistribution(Basic):
def __call__(self, *args):
return self.pdf(*args)
class SingleDiscreteDistribution(DiscreteDistribution, NamedArgsMixin):
""" Discrete distribution of a single variable
Serves as superclass for PoissonDistribution etc....
Provides methods for pdf, cdf, and sampling
See Also:
sympy.stats.crv_types.*
"""
set = S.Integers
def __new__(cls, *args):
args = list(map(sympify, args))
return Basic.__new__(cls, *args)
@staticmethod
def check(*args):
pass
def sample(self):
""" A random realization from the distribution """
icdf = self._inverse_cdf_expression()
while True:
sample_ = floor(list(icdf(random.uniform(0, 1)))[0])
if sample_ >= self.set.inf:
return sample_
@cacheit
def _inverse_cdf_expression(self):
""" Inverse of the CDF
Used by sample
"""
x = symbols('x', positive=True,
integer=True, cls=Dummy)
z = symbols('z', positive=True, cls=Dummy)
cdf_temp = self.cdf(x)
# Invert CDF
try:
inverse_cdf = solveset(cdf_temp - z, x, domain=S.Reals)
except NotImplementedError:
inverse_cdf = None
if not inverse_cdf or len(inverse_cdf.free_symbols) != 1:
raise NotImplementedError("Could not invert CDF")
return Lambda(z, inverse_cdf)
@cacheit
def compute_cdf(self, **kwargs):
""" Compute the CDF from the PDF
Returns a Lambda
"""
x, z = symbols('x, z', integer=True, finite=True, cls=Dummy)
left_bound = self.set.inf
# CDF is integral of PDF from left bound to z
pdf = self.pdf(x)
cdf = summation(pdf, (x, left_bound, z), **kwargs)
# CDF Ensure that CDF left of left_bound is zero
cdf = Piecewise((cdf, z >= left_bound), (0, True))
return Lambda(z, cdf)
def _cdf(self, x):
return None
def cdf(self, x, **kwargs):
""" Cumulative density function """
if not kwargs:
cdf = self._cdf(x)
if cdf is not None:
return cdf
return self.compute_cdf(**kwargs)(x)
@cacheit
def compute_characteristic_function(self, **kwargs):
""" Compute the characteristic function from the PDF
Returns a Lambda
"""
x, t = symbols('x, t', real=True, finite=True, cls=Dummy)
pdf = self.pdf(x)
cf = summation(exp(I*t*x)*pdf, (x, self.set.inf, self.set.sup))
return Lambda(t, cf)
def _characteristic_function(self, t):
return None
def characteristic_function(self, t, **kwargs):
""" Characteristic function """
if not kwargs:
cf = self._characteristic_function(t)
if cf is not None:
return cf
return self.compute_characteristic_function(**kwargs)(t)
@cacheit
def compute_moment_generating_function(self, **kwargs):
x, t = symbols('x, t', real=True, finite=True, cls=Dummy)
pdf = self.pdf(x)
mgf = summation(exp(t*x)*pdf, (x, self.set.inf, self.set.sup))
return Lambda(t, mgf)
def _moment_generating_function(self, t):
return None
def moment_generating_function(self, t, **kwargs):
if not kwargs:
mgf = self._moment_generating_function(t)
if mgf is not None:
return mgf
return self.compute_moment_generating_function(**kwargs)(t)
def expectation(self, expr, var, evaluate=True, **kwargs):
""" Expectation of expression over distribution """
# TODO: support discrete sets with non integer stepsizes
if evaluate:
try:
p = poly(expr, var)
t = Dummy('t', real=True)
mgf = self.moment_generating_function(t)
deg = p.degree()
taylor = poly(series(mgf, t, 0, deg + 1).removeO(), t)
result = 0
for k in range(deg+1):
result += p.coeff_monomial(var ** k) * taylor.coeff_monomial(t ** k) * factorial(k)
return result
except PolynomialError:
return summation(expr * self.pdf(var),
(var, self.set.inf, self.set.sup), **kwargs)
else:
return Sum(expr * self.pdf(var),
(var, self.set.inf, self.set.sup), **kwargs)
def __call__(self, *args):
return self.pdf(*args)
class DiscreteDistributionHandmade(SingleDiscreteDistribution):
_argnames = ('pdf',)
@property
def set(self):
return self.args[1]
def __new__(cls, pdf, set=S.Integers):
return Basic.__new__(cls, pdf, set)
class DiscreteDomain(RandomDomain):
"""
A domain with discrete support with step size one.
Represented using symbols and Range.
"""
is_Discrete = True
class SingleDiscreteDomain(DiscreteDomain, SingleDomain):
def as_boolean(self):
return Contains(self.symbol, self.set)
class ConditionalDiscreteDomain(DiscreteDomain, ConditionalDomain):
"""
Domain with discrete support of step size one, that is restricted by
some condition.
"""
@property
def set(self):
rv = self.symbols
if len(self.symbols) > 1:
raise NotImplementedError(filldedent('''
Multivariate condtional domains are not yet implemented.'''))
rv = list(rv)[0]
return reduce_rational_inequalities_wrap(self.condition,
rv).intersect(self.fulldomain.set)
class DiscretePSpace(PSpace):
is_real = True
is_Discrete = True
@property
def pdf(self):
return self.density(*self.symbols)
def where(self, condition):
rvs = random_symbols(condition)
assert all(r.symbol in self.symbols for r in rvs)
if (len(rvs) > 1):
raise NotImplementedError(filldedent('''Multivariate discrete
random variables are not yet supported.'''))
conditional_domain = reduce_rational_inequalities_wrap(condition,
rvs[0])
conditional_domain = conditional_domain.intersect(self.domain.set)
return SingleDiscreteDomain(rvs[0].symbol, conditional_domain)
def probability(self, condition):
complement = isinstance(condition, Ne)
if complement:
condition = Eq(condition.args[0], condition.args[1])
try:
_domain = self.where(condition).set
if condition == False or _domain is S.EmptySet:
return S.Zero
if condition == True or _domain == self.domain.set:
return S.One
prob = self.eval_prob(_domain)
except NotImplementedError:
from sympy.stats.rv import density
expr = condition.lhs - condition.rhs
dens = density(expr)
if not isinstance(dens, DiscreteDistribution):
dens = DiscreteDistributionHandmade(dens)
z = Dummy('z', real = True)
space = SingleDiscretePSpace(z, dens)
prob = space.probability(condition.__class__(space.value, 0))
if (prob == None):
prob = Probability(condition)
return prob if not complement else S.One - prob
def eval_prob(self, _domain):
sym = list(self.symbols)[0]
if isinstance(_domain, Range):
n = symbols('n', integer=True, finite=True)
inf, sup, step = (r for r in _domain.args)
summand = ((self.pdf).replace(
sym, n*step))
rv = summation(summand,
(n, inf/step, (sup)/step - 1)).doit()
return rv
elif isinstance(_domain, FiniteSet):
pdf = Lambda(sym, self.pdf)
rv = sum(pdf(x) for x in _domain)
return rv
elif isinstance(_domain, Union):
rv = sum(self.eval_prob(x) for x in _domain.args)
return rv
def conditional_space(self, condition):
density = Lambda(self.symbols, self.pdf/self.probability(condition))
condition = condition.xreplace(dict((rv, rv.symbol) for rv in self.values))
domain = ConditionalDiscreteDomain(self.domain, condition)
return DiscretePSpace(domain, density)
class ProductDiscreteDomain(ProductDomain, DiscreteDomain):
def as_boolean(self):
return And(*[domain.as_boolean for domain in self.domains])
class SingleDiscretePSpace(DiscretePSpace, SinglePSpace):
""" Discrete probability space over a single univariate variable """
is_real = True
@property
def set(self):
return self.distribution.set
@property
def domain(self):
return SingleDiscreteDomain(self.symbol, self.set)
def sample(self):
"""
Internal sample method
Returns dictionary mapping RandomSymbol to realization value.
"""
return {self.value: self.distribution.sample()}
def compute_expectation(self, expr, rvs=None, evaluate=True, **kwargs):
rvs = rvs or (self.value,)
if self.value not in rvs:
return expr
expr = expr.xreplace(dict((rv, rv.symbol) for rv in rvs))
x = self.value.symbol
try:
return self.distribution.expectation(expr, x, evaluate=evaluate,
**kwargs)
except NotImplementedError:
return Sum(expr * self.pdf, (x, self.set.inf, self.set.sup),
**kwargs)
def compute_cdf(self, expr, **kwargs):
if expr == self.value:
x = symbols("x", real=True, cls=Dummy)
return Lambda(x, self.distribution.cdf(x, **kwargs))
else:
raise NotImplementedError()
def compute_density(self, expr, **kwargs):
if expr == self.value:
return self.distribution
raise NotImplementedError()
def compute_characteristic_function(self, expr, **kwargs):
if expr == self.value:
t = symbols("t", real=True, cls=Dummy)
return Lambda(t, self.distribution.characteristic_function(t, **kwargs))
else:
raise NotImplementedError()
def compute_moment_generating_function(self, expr, **kwargs):
if expr == self.value:
t = symbols("t", real=True, cls=Dummy)
return Lambda(t, self.distribution.moment_generating_function(t, **kwargs))
else:
raise NotImplementedError()
|
a448d8f6b2ef8be8993087cc5b6c1be1a366b8e061de68ae20d3b5d715e54a62
|
"""
Continuous Random Variables Module
See Also
========
sympy.stats.crv_types
sympy.stats.rv
sympy.stats.frv
"""
from __future__ import print_function, division
from sympy import (Interval, Intersection, symbols, sympify, Dummy,
Integral, And, Or, Piecewise, cacheit, integrate, oo, Lambda,
Basic, S, exp, I, FiniteSet, Ne, Eq, Union, poly, series, factorial)
from sympy.functions.special.delta_functions import DiracDelta
from sympy.polys.polyerrors import PolynomialError
from sympy.solvers.solveset import solveset
from sympy.solvers.inequalities import reduce_rational_inequalities
from sympy.stats.rv import (RandomDomain, SingleDomain, ConditionalDomain,
ProductDomain, PSpace, SinglePSpace, random_symbols, NamedArgsMixin)
import random
class ContinuousDomain(RandomDomain):
"""
A domain with continuous support
Represented using symbols and Intervals.
"""
is_Continuous = True
def as_boolean(self):
raise NotImplementedError("Not Implemented for generic Domains")
class SingleContinuousDomain(ContinuousDomain, SingleDomain):
"""
A univariate domain with continuous support
Represented using a single symbol and interval.
"""
def compute_expectation(self, expr, variables=None, **kwargs):
if variables is None:
variables = self.symbols
if not variables:
return expr
if frozenset(variables) != frozenset(self.symbols):
raise ValueError("Values should be equal")
# assumes only intervals
return Integral(expr, (self.symbol, self.set), **kwargs)
def as_boolean(self):
return self.set.as_relational(self.symbol)
class ProductContinuousDomain(ProductDomain, ContinuousDomain):
"""
A collection of independent domains with continuous support
"""
def compute_expectation(self, expr, variables=None, **kwargs):
if variables is None:
variables = self.symbols
for domain in self.domains:
domain_vars = frozenset(variables) & frozenset(domain.symbols)
if domain_vars:
expr = domain.compute_expectation(expr, domain_vars, **kwargs)
return expr
def as_boolean(self):
return And(*[domain.as_boolean() for domain in self.domains])
class ConditionalContinuousDomain(ContinuousDomain, ConditionalDomain):
"""
A domain with continuous support that has been further restricted by a
condition such as x > 3
"""
def compute_expectation(self, expr, variables=None, **kwargs):
if variables is None:
variables = self.symbols
if not variables:
return expr
# Extract the full integral
fullintgrl = self.fulldomain.compute_expectation(expr, variables)
# separate into integrand and limits
integrand, limits = fullintgrl.function, list(fullintgrl.limits)
conditions = [self.condition]
while conditions:
cond = conditions.pop()
if cond.is_Boolean:
if isinstance(cond, And):
conditions.extend(cond.args)
elif isinstance(cond, Or):
raise NotImplementedError("Or not implemented here")
elif cond.is_Relational:
if cond.is_Equality:
# Add the appropriate Delta to the integrand
integrand *= DiracDelta(cond.lhs - cond.rhs)
else:
symbols = cond.free_symbols & set(self.symbols)
if len(symbols) != 1: # Can't handle x > y
raise NotImplementedError(
"Multivariate Inequalities not yet implemented")
# Can handle x > 0
symbol = symbols.pop()
# Find the limit with x, such as (x, -oo, oo)
for i, limit in enumerate(limits):
if limit[0] == symbol:
# Make condition into an Interval like [0, oo]
cintvl = reduce_rational_inequalities_wrap(
cond, symbol)
# Make limit into an Interval like [-oo, oo]
lintvl = Interval(limit[1], limit[2])
# Intersect them to get [0, oo]
intvl = cintvl.intersect(lintvl)
# Put back into limits list
limits[i] = (symbol, intvl.left, intvl.right)
else:
raise TypeError(
"Condition %s is not a relational or Boolean" % cond)
return Integral(integrand, *limits, **kwargs)
def as_boolean(self):
return And(self.fulldomain.as_boolean(), self.condition)
@property
def set(self):
if len(self.symbols) == 1:
return (self.fulldomain.set & reduce_rational_inequalities_wrap(
self.condition, tuple(self.symbols)[0]))
else:
raise NotImplementedError(
"Set of Conditional Domain not Implemented")
class ContinuousDistribution(Basic):
def __call__(self, *args):
return self.pdf(*args)
class SingleContinuousDistribution(ContinuousDistribution, NamedArgsMixin):
""" Continuous distribution of a single variable
Serves as superclass for Normal/Exponential/UniformDistribution etc....
Represented by parameters for each of the specific classes. E.g
NormalDistribution is represented by a mean and standard deviation.
Provides methods for pdf, cdf, and sampling
See Also
========
sympy.stats.crv_types.*
"""
set = Interval(-oo, oo)
def __new__(cls, *args):
args = list(map(sympify, args))
return Basic.__new__(cls, *args)
@staticmethod
def check(*args):
pass
def sample(self):
""" A random realization from the distribution """
icdf = self._inverse_cdf_expression()
return icdf(random.uniform(0, 1))
@cacheit
def _inverse_cdf_expression(self):
""" Inverse of the CDF
Used by sample
"""
x, z = symbols('x, z', real=True, positive=True, cls=Dummy)
# Invert CDF
try:
inverse_cdf = solveset(self.cdf(x) - z, x, S.Reals)
if isinstance(inverse_cdf, Intersection) and S.Reals in inverse_cdf.args:
inverse_cdf = list(inverse_cdf.args[1])
except NotImplementedError:
inverse_cdf = None
if not inverse_cdf or len(inverse_cdf) != 1:
raise NotImplementedError("Could not invert CDF")
return Lambda(z, inverse_cdf[0])
@cacheit
def compute_cdf(self, **kwargs):
""" Compute the CDF from the PDF
Returns a Lambda
"""
x, z = symbols('x, z', real=True, finite=True, cls=Dummy)
left_bound = self.set.start
# CDF is integral of PDF from left bound to z
pdf = self.pdf(x)
cdf = integrate(pdf, (x, left_bound, z), **kwargs)
# CDF Ensure that CDF left of left_bound is zero
cdf = Piecewise((cdf, z >= left_bound), (0, True))
return Lambda(z, cdf)
def _cdf(self, x):
return None
def cdf(self, x, **kwargs):
""" Cumulative density function """
if len(kwargs) == 0:
cdf = self._cdf(x)
if cdf is not None:
return cdf
return self.compute_cdf(**kwargs)(x)
@cacheit
def compute_characteristic_function(self, **kwargs):
""" Compute the characteristic function from the PDF
Returns a Lambda
"""
x, t = symbols('x, t', real=True, finite=True, cls=Dummy)
pdf = self.pdf(x)
cf = integrate(exp(I*t*x)*pdf, (x, -oo, oo))
return Lambda(t, cf)
def _characteristic_function(self, t):
return None
def characteristic_function(self, t, **kwargs):
""" Characteristic function """
if len(kwargs) == 0:
cf = self._characteristic_function(t)
if cf is not None:
return cf
return self.compute_characteristic_function(**kwargs)(t)
@cacheit
def compute_moment_generating_function(self, **kwargs):
""" Compute the moment generating function from the PDF
Returns a Lambda
"""
x, t = symbols('x, t', real=True, cls=Dummy)
pdf = self.pdf(x)
mgf = integrate(exp(t * x) * pdf, (x, -oo, oo))
return Lambda(t, mgf)
def _moment_generating_function(self, t):
return None
def moment_generating_function(self, t, **kwargs):
""" Moment generating function """
if len(kwargs) == 0:
try:
mgf = self._moment_generating_function(t)
if mgf is not None:
return mgf
except NotImplementedError:
return None
return self.compute_moment_generating_function(**kwargs)(t)
def expectation(self, expr, var, evaluate=True, **kwargs):
""" Expectation of expression over distribution """
if evaluate:
try:
p = poly(expr, var)
t = Dummy('t', real=True)
mgf = self._moment_generating_function(t)
if mgf is None:
return integrate(expr * self.pdf(var), (var, self.set), **kwargs)
deg = p.degree()
taylor = poly(series(mgf, t, 0, deg + 1).removeO(), t)
result = 0
for k in range(deg+1):
result += p.coeff_monomial(var ** k) * taylor.coeff_monomial(t ** k) * factorial(k)
return result
except PolynomialError:
return integrate(expr * self.pdf(var), (var, self.set), **kwargs)
else:
return Integral(expr * self.pdf(var), (var, self.set), **kwargs)
class ContinuousDistributionHandmade(SingleContinuousDistribution):
_argnames = ('pdf',)
@property
def set(self):
return self.args[1]
def __new__(cls, pdf, set=Interval(-oo, oo)):
return Basic.__new__(cls, pdf, set)
class ContinuousPSpace(PSpace):
""" Continuous Probability Space
Represents the likelihood of an event space defined over a continuum.
Represented with a ContinuousDomain and a PDF (Lambda-Like)
"""
is_Continuous = True
is_real = True
@property
def pdf(self):
return self.density(*self.domain.symbols)
def compute_expectation(self, expr, rvs=None, evaluate=False, **kwargs):
if rvs is None:
rvs = self.values
else:
rvs = frozenset(rvs)
expr = expr.xreplace(dict((rv, rv.symbol) for rv in rvs))
domain_symbols = frozenset(rv.symbol for rv in rvs)
return self.domain.compute_expectation(self.pdf * expr,
domain_symbols, **kwargs)
def compute_density(self, expr, **kwargs):
# Common case Density(X) where X in self.values
if expr in self.values:
# Marginalize all other random symbols out of the density
randomsymbols = tuple(set(self.values) - frozenset([expr]))
symbols = tuple(rs.symbol for rs in randomsymbols)
pdf = self.domain.compute_expectation(self.pdf, symbols, **kwargs)
return Lambda(expr.symbol, pdf)
z = Dummy('z', real=True, finite=True)
return Lambda(z, self.compute_expectation(DiracDelta(expr - z), **kwargs))
@cacheit
def compute_cdf(self, expr, **kwargs):
if not self.domain.set.is_Interval:
raise ValueError(
"CDF not well defined on multivariate expressions")
d = self.compute_density(expr, **kwargs)
x, z = symbols('x, z', real=True, finite=True, cls=Dummy)
left_bound = self.domain.set.start
# CDF is integral of PDF from left bound to z
cdf = integrate(d(x), (x, left_bound, z), **kwargs)
# CDF Ensure that CDF left of left_bound is zero
cdf = Piecewise((cdf, z >= left_bound), (0, True))
return Lambda(z, cdf)
@cacheit
def compute_characteristic_function(self, expr, **kwargs):
if not self.domain.set.is_Interval:
raise NotImplementedError("Characteristic function of multivariate expressions not implemented")
d = self.compute_density(expr, **kwargs)
x, t = symbols('x, t', real=True, cls=Dummy)
cf = integrate(exp(I*t*x)*d(x), (x, -oo, oo), **kwargs)
return Lambda(t, cf)
@cacheit
def compute_moment_generating_function(self, expr, **kwargs):
if not self.domain.set.is_Interval:
raise NotImplementedError("Moment generating function of multivariate expressions not implemented")
d = self.compute_density(expr, **kwargs)
x, t = symbols('x, t', real=True, cls=Dummy)
mgf = integrate(exp(t * x) * d(x), (x, -oo, oo), **kwargs)
return Lambda(t, mgf)
def probability(self, condition, **kwargs):
z = Dummy('z', real=True, finite=True)
cond_inv = False
if isinstance(condition, Ne):
condition = Eq(condition.args[0], condition.args[1])
cond_inv = True
# Univariate case can be handled by where
try:
domain = self.where(condition)
rv = [rv for rv in self.values if rv.symbol == domain.symbol][0]
# Integrate out all other random variables
pdf = self.compute_density(rv, **kwargs)
# return S.Zero if `domain` is empty set
if domain.set is S.EmptySet or isinstance(domain.set, FiniteSet):
return S.Zero if not cond_inv else S.One
if isinstance(domain.set, Union):
return sum(
Integral(pdf(z), (z, subset), **kwargs) for subset in
domain.set.args if isinstance(subset, Interval))
# Integrate out the last variable over the special domain
return Integral(pdf(z), (z, domain.set), **kwargs)
# Other cases can be turned into univariate case
# by computing a density handled by density computation
except NotImplementedError:
from sympy.stats.rv import density
expr = condition.lhs - condition.rhs
dens = density(expr, **kwargs)
if not isinstance(dens, ContinuousDistribution):
dens = ContinuousDistributionHandmade(dens)
# Turn problem into univariate case
space = SingleContinuousPSpace(z, dens)
result = space.probability(condition.__class__(space.value, 0))
return result if not cond_inv else S.One - result
def where(self, condition):
rvs = frozenset(random_symbols(condition))
if not (len(rvs) == 1 and rvs.issubset(self.values)):
raise NotImplementedError(
"Multiple continuous random variables not supported")
rv = tuple(rvs)[0]
interval = reduce_rational_inequalities_wrap(condition, rv)
interval = interval.intersect(self.domain.set)
return SingleContinuousDomain(rv.symbol, interval)
def conditional_space(self, condition, normalize=True, **kwargs):
condition = condition.xreplace(dict((rv, rv.symbol) for rv in self.values))
domain = ConditionalContinuousDomain(self.domain, condition)
if normalize:
# create a clone of the variable to
# make sure that variables in nested integrals are different
# from the variables outside the integral
# this makes sure that they are evaluated separately
# and in the correct order
replacement = {rv: Dummy(str(rv)) for rv in self.symbols}
norm = domain.compute_expectation(self.pdf, **kwargs)
pdf = self.pdf / norm.xreplace(replacement)
density = Lambda(domain.symbols, pdf)
return ContinuousPSpace(domain, density)
class SingleContinuousPSpace(ContinuousPSpace, SinglePSpace):
"""
A continuous probability space over a single univariate variable
These consist of a Symbol and a SingleContinuousDistribution
This class is normally accessed through the various random variable
functions, Normal, Exponential, Uniform, etc....
"""
@property
def set(self):
return self.distribution.set
@property
def domain(self):
return SingleContinuousDomain(sympify(self.symbol), self.set)
def sample(self):
"""
Internal sample method
Returns dictionary mapping RandomSymbol to realization value.
"""
return {self.value: self.distribution.sample()}
def compute_expectation(self, expr, rvs=None, evaluate=False, **kwargs):
rvs = rvs or (self.value,)
if self.value not in rvs:
return expr
expr = expr.xreplace(dict((rv, rv.symbol) for rv in rvs))
x = self.value.symbol
try:
return self.distribution.expectation(expr, x, evaluate=evaluate, **kwargs)
except Exception:
return Integral(expr * self.pdf, (x, self.set), **kwargs)
def compute_cdf(self, expr, **kwargs):
if expr == self.value:
z = symbols("z", real=True, finite=True, cls=Dummy)
return Lambda(z, self.distribution.cdf(z, **kwargs))
else:
return ContinuousPSpace.compute_cdf(self, expr, **kwargs)
def compute_characteristic_function(self, expr, **kwargs):
if expr == self.value:
t = symbols("t", real=True, cls=Dummy)
return Lambda(t, self.distribution.characteristic_function(t, **kwargs))
else:
return ContinuousPSpace.compute_characteristic_function(self, expr, **kwargs)
def compute_moment_generating_function(self, expr, **kwargs):
if expr == self.value:
t = symbols("t", real=True, cls=Dummy)
return Lambda(t, self.distribution.moment_generating_function(t, **kwargs))
else:
return ContinuousPSpace.compute_moment_generating_function(self, expr, **kwargs)
def compute_density(self, expr, **kwargs):
# https://en.wikipedia.org/wiki/Random_variable#Functions_of_random_variables
if expr == self.value:
return self.density
y = Dummy('y')
gs = solveset(expr - y, self.value, S.Reals)
if isinstance(gs, Intersection) and S.Reals in gs.args:
gs = list(gs.args[1])
if not gs:
raise ValueError("Can not solve %s for %s"%(expr, self.value))
fx = self.compute_density(self.value)
fy = sum(fx(g) * abs(g.diff(y)) for g in gs)
return Lambda(y, fy)
def _reduce_inequalities(conditions, var, **kwargs):
try:
return reduce_rational_inequalities(conditions, var, **kwargs)
except PolynomialError:
raise ValueError("Reduction of condition failed %s\n" % conditions[0])
def reduce_rational_inequalities_wrap(condition, var):
if condition.is_Relational:
return _reduce_inequalities([[condition]], var, relational=False)
if isinstance(condition, Or):
return Union(*[_reduce_inequalities([[arg]], var, relational=False)
for arg in condition.args])
if isinstance(condition, And):
intervals = [_reduce_inequalities([[arg]], var, relational=False)
for arg in condition.args]
I = intervals[0]
for i in intervals:
I = I.intersect(i)
return I
|
7753cf35dc7b3eb67cc44315b9f984deabafacbfd796e656ff6dfe6d1994d4d5
|
import itertools
from sympy import Expr, Add, Mul, S, Integral, Eq, Sum, Symbol
from sympy.core.compatibility import default_sort_key
from sympy.core.evaluate import global_evaluate
from sympy.core.sympify import _sympify
from sympy.stats import variance, covariance
from sympy.stats.rv import RandomSymbol, probability, expectation
__all__ = ['Probability', 'Expectation', 'Variance', 'Covariance']
class Probability(Expr):
"""
Symbolic expression for the probability.
Examples
========
>>> from sympy.stats import Probability, Normal
>>> from sympy import Integral
>>> X = Normal("X", 0, 1)
>>> prob = Probability(X > 1)
>>> prob
Probability(X > 1)
Integral representation:
>>> prob.rewrite(Integral)
Integral(sqrt(2)*exp(-_z**2/2)/(2*sqrt(pi)), (_z, 1, oo))
Evaluation of the integral:
>>> prob.evaluate_integral()
sqrt(2)*(-sqrt(2)*sqrt(pi)*erf(sqrt(2)/2) + sqrt(2)*sqrt(pi))/(4*sqrt(pi))
"""
def __new__(cls, prob, condition=None, **kwargs):
prob = _sympify(prob)
if condition is None:
obj = Expr.__new__(cls, prob)
else:
condition = _sympify(condition)
obj = Expr.__new__(cls, prob, condition)
obj._condition = condition
return obj
def _eval_rewrite_as_Integral(self, arg, condition=None, **kwargs):
return probability(arg, condition, evaluate=False)
def _eval_rewrite_as_Sum(self, arg, condition=None, **kwargs):
return probability(arg, condition, evaluate=False)
def evaluate_integral(self):
return self.rewrite(Integral).doit()
class Expectation(Expr):
"""
Symbolic expression for the expectation.
Examples
========
>>> from sympy.stats import Expectation, Normal, Probability
>>> from sympy import symbols, Integral
>>> mu = symbols("mu")
>>> sigma = symbols("sigma", positive=True)
>>> X = Normal("X", mu, sigma)
>>> Expectation(X)
Expectation(X)
>>> Expectation(X).evaluate_integral().simplify()
mu
To get the integral expression of the expectation:
>>> Expectation(X).rewrite(Integral)
Integral(sqrt(2)*X*exp(-(X - mu)**2/(2*sigma**2))/(2*sqrt(pi)*sigma), (X, -oo, oo))
The same integral expression, in more abstract terms:
>>> Expectation(X).rewrite(Probability)
Integral(x*Probability(Eq(X, x)), (x, -oo, oo))
This class is aware of some properties of the expectation:
>>> from sympy.abc import a
>>> Expectation(a*X)
Expectation(a*X)
>>> Y = Normal("Y", 0, 1)
>>> Expectation(X + Y)
Expectation(X + Y)
To expand the ``Expectation`` into its expression, use ``doit()``:
>>> Expectation(X + Y).doit()
Expectation(X) + Expectation(Y)
>>> Expectation(a*X + Y).doit()
a*Expectation(X) + Expectation(Y)
>>> Expectation(a*X + Y)
Expectation(a*X + Y)
"""
def __new__(cls, expr, condition=None, **kwargs):
expr = _sympify(expr)
if condition is None:
if not expr.has(RandomSymbol):
return expr
obj = Expr.__new__(cls, expr)
else:
condition = _sympify(condition)
obj = Expr.__new__(cls, expr, condition)
obj._condition = condition
return obj
def doit(self, **hints):
expr = self.args[0]
condition = self._condition
if not expr.has(RandomSymbol):
return expr
if isinstance(expr, Add):
return Add(*[Expectation(a, condition=condition).doit() for a in expr.args])
elif isinstance(expr, Mul):
rv = []
nonrv = []
for a in expr.args:
if isinstance(a, RandomSymbol) or a.has(RandomSymbol):
rv.append(a)
else:
nonrv.append(a)
return Mul(*nonrv)*Expectation(Mul(*rv), condition=condition)
return self
def _eval_rewrite_as_Probability(self, arg, condition=None, **kwargs):
rvs = arg.atoms(RandomSymbol)
if len(rvs) > 1:
raise NotImplementedError()
if len(rvs) == 0:
return arg
rv = rvs.pop()
if rv.pspace is None:
raise ValueError("Probability space not known")
symbol = rv.symbol
if symbol.name[0].isupper():
symbol = Symbol(symbol.name.lower())
else :
symbol = Symbol(symbol.name + "_1")
if rv.pspace.is_Continuous:
return Integral(arg.replace(rv, symbol)*Probability(Eq(rv, symbol), condition), (symbol, rv.pspace.domain.set.inf, rv.pspace.domain.set.sup))
else:
if rv.pspace.is_Finite:
raise NotImplementedError
else:
return Sum(arg.replace(rv, symbol)*Probability(Eq(rv, symbol), condition), (symbol, rv.pspace.domain.set.inf, rv.pspace.set.sup))
def _eval_rewrite_as_Integral(self, arg, condition=None, **kwargs):
return expectation(arg, condition=condition, evaluate=False)
def _eval_rewrite_as_Sum(self, arg, condition=None, **kwargs):
return self.rewrite(Integral)
def evaluate_integral(self):
return self.rewrite(Integral).doit()
class Variance(Expr):
"""
Symbolic expression for the variance.
Examples
========
>>> from sympy import symbols, Integral
>>> from sympy.stats import Normal, Expectation, Variance, Probability
>>> mu = symbols("mu", positive=True)
>>> sigma = symbols("sigma", positive=True)
>>> X = Normal("X", mu, sigma)
>>> Variance(X)
Variance(X)
>>> Variance(X).evaluate_integral()
sigma**2
Integral representation of the underlying calculations:
>>> Variance(X).rewrite(Integral)
Integral(sqrt(2)*(X - Integral(sqrt(2)*X*exp(-(X - mu)**2/(2*sigma**2))/(2*sqrt(pi)*sigma), (X, -oo, oo)))**2*exp(-(X - mu)**2/(2*sigma**2))/(2*sqrt(pi)*sigma), (X, -oo, oo))
Integral representation, without expanding the PDF:
>>> Variance(X).rewrite(Probability)
-Integral(x*Probability(Eq(X, x)), (x, -oo, oo))**2 + Integral(x**2*Probability(Eq(X, x)), (x, -oo, oo))
Rewrite the variance in terms of the expectation
>>> Variance(X).rewrite(Expectation)
-Expectation(X)**2 + Expectation(X**2)
Some transformations based on the properties of the variance may happen:
>>> from sympy.abc import a
>>> Y = Normal("Y", 0, 1)
>>> Variance(a*X)
Variance(a*X)
To expand the variance in its expression, use ``doit()``:
>>> Variance(a*X).doit()
a**2*Variance(X)
>>> Variance(X + Y)
Variance(X + Y)
>>> Variance(X + Y).doit()
2*Covariance(X, Y) + Variance(X) + Variance(Y)
"""
def __new__(cls, arg, condition=None, **kwargs):
arg = _sympify(arg)
if condition is None:
obj = Expr.__new__(cls, arg)
else:
condition = _sympify(condition)
obj = Expr.__new__(cls, arg, condition)
obj._condition = condition
return obj
def doit(self, **hints):
arg = self.args[0]
condition = self._condition
if not arg.has(RandomSymbol):
return S.Zero
if isinstance(arg, RandomSymbol):
return self
elif isinstance(arg, Add):
rv = []
for a in arg.args:
if a.has(RandomSymbol):
rv.append(a)
variances = Add(*map(lambda xv: Variance(xv, condition).doit(), rv))
map_to_covar = lambda x: 2*Covariance(*x, condition=condition).doit()
covariances = Add(*map(map_to_covar, itertools.combinations(rv, 2)))
return variances + covariances
elif isinstance(arg, Mul):
nonrv = []
rv = []
for a in arg.args:
if a.has(RandomSymbol):
rv.append(a)
else:
nonrv.append(a**2)
if len(rv) == 0:
return S.Zero
return Mul(*nonrv)*Variance(Mul(*rv), condition)
# this expression contains a RandomSymbol somehow:
return self
def _eval_rewrite_as_Expectation(self, arg, condition=None, **kwargs):
e1 = Expectation(arg**2, condition)
e2 = Expectation(arg, condition)**2
return e1 - e2
def _eval_rewrite_as_Probability(self, arg, condition=None, **kwargs):
return self.rewrite(Expectation).rewrite(Probability)
def _eval_rewrite_as_Integral(self, arg, condition=None, **kwargs):
return variance(self.args[0], self._condition, evaluate=False)
def _eval_rewrite_as_Sum(self, arg, condition=None, **kwargs):
return self.rewrite(Integral)
def evaluate_integral(self):
return self.rewrite(Integral).doit()
class Covariance(Expr):
"""
Symbolic expression for the covariance.
Examples
========
>>> from sympy.stats import Covariance
>>> from sympy.stats import Normal
>>> X = Normal("X", 3, 2)
>>> Y = Normal("Y", 0, 1)
>>> Z = Normal("Z", 0, 1)
>>> W = Normal("W", 0, 1)
>>> cexpr = Covariance(X, Y)
>>> cexpr
Covariance(X, Y)
Evaluate the covariance, `X` and `Y` are independent,
therefore zero is the result:
>>> cexpr.evaluate_integral()
0
Rewrite the covariance expression in terms of expectations:
>>> from sympy.stats import Expectation
>>> cexpr.rewrite(Expectation)
Expectation(X*Y) - Expectation(X)*Expectation(Y)
In order to expand the argument, use ``doit()``:
>>> from sympy.abc import a, b, c, d
>>> Covariance(a*X + b*Y, c*Z + d*W)
Covariance(a*X + b*Y, c*Z + d*W)
>>> Covariance(a*X + b*Y, c*Z + d*W).doit()
a*c*Covariance(X, Z) + a*d*Covariance(W, X) + b*c*Covariance(Y, Z) + b*d*Covariance(W, Y)
This class is aware of some properties of the covariance:
>>> Covariance(X, X).doit()
Variance(X)
>>> Covariance(a*X, b*Y).doit()
a*b*Covariance(X, Y)
"""
def __new__(cls, arg1, arg2, condition=None, **kwargs):
arg1 = _sympify(arg1)
arg2 = _sympify(arg2)
if kwargs.pop('evaluate', global_evaluate[0]):
arg1, arg2 = sorted([arg1, arg2], key=default_sort_key)
if condition is None:
obj = Expr.__new__(cls, arg1, arg2)
else:
condition = _sympify(condition)
obj = Expr.__new__(cls, arg1, arg2, condition)
obj._condition = condition
return obj
def doit(self, **hints):
arg1 = self.args[0]
arg2 = self.args[1]
condition = self._condition
if arg1 == arg2:
return Variance(arg1, condition).doit()
if not arg1.has(RandomSymbol):
return S.Zero
if not arg2.has(RandomSymbol):
return S.Zero
arg1, arg2 = sorted([arg1, arg2], key=default_sort_key)
if isinstance(arg1, RandomSymbol) and isinstance(arg2, RandomSymbol):
return Covariance(arg1, arg2, condition)
coeff_rv_list1 = self._expand_single_argument(arg1.expand())
coeff_rv_list2 = self._expand_single_argument(arg2.expand())
addends = [a*b*Covariance(*sorted([r1, r2], key=default_sort_key), condition=condition)
for (a, r1) in coeff_rv_list1 for (b, r2) in coeff_rv_list2]
return Add(*addends)
@classmethod
def _expand_single_argument(cls, expr):
# return (coefficient, random_symbol) pairs:
if isinstance(expr, RandomSymbol):
return [(S.One, expr)]
elif isinstance(expr, Add):
outval = []
for a in expr.args:
if isinstance(a, Mul):
outval.append(cls._get_mul_nonrv_rv_tuple(a))
elif isinstance(a, RandomSymbol):
outval.append((S.One, a))
return outval
elif isinstance(expr, Mul):
return [cls._get_mul_nonrv_rv_tuple(expr)]
elif expr.has(RandomSymbol):
return [(S.One, expr)]
@classmethod
def _get_mul_nonrv_rv_tuple(cls, m):
rv = []
nonrv = []
for a in m.args:
if a.has(RandomSymbol):
rv.append(a)
else:
nonrv.append(a)
return (Mul(*nonrv), Mul(*rv))
def _eval_rewrite_as_Expectation(self, arg1, arg2, condition=None, **kwargs):
e1 = Expectation(arg1*arg2, condition)
e2 = Expectation(arg1, condition)*Expectation(arg2, condition)
return e1 - e2
def _eval_rewrite_as_Probability(self, arg1, arg2, condition=None, **kwargs):
return self.rewrite(Expectation).rewrite(Probability)
def _eval_rewrite_as_Integral(self, arg1, arg2, condition=None, **kwargs):
return covariance(self.args[0], self.args[1], self._condition, evaluate=False)
def _eval_rewrite_as_Sum(self, arg1, arg2, condition=None, **kwargs):
return self.rewrite(Integral)
def evaluate_integral(self):
return self.rewrite(Integral).doit()
|
1c74efea0fec0690e4a942e6ab0e1ec67d6bcb79347a3a5cbd03caa390de24cd
|
"""
Generating and counting primes.
"""
from __future__ import print_function, division
import random
from bisect import bisect
# Using arrays for sieving instead of lists greatly reduces
# memory consumption
from array import array as _array
from sympy import Function, S
from sympy.core.compatibility import as_int, range
from .primetest import isprime
def _azeros(n):
return _array('l', [0]*n)
def _aset(*v):
return _array('l', v)
def _arange(a, b):
return _array('l', range(a, b))
class Sieve:
"""An infinite list of prime numbers, implemented as a dynamically
growing sieve of Eratosthenes. When a lookup is requested involving
an odd number that has not been sieved, the sieve is automatically
extended up to that number.
Examples
========
>>> from sympy import sieve
>>> sieve._reset() # this line for doctest only
>>> 25 in sieve
False
>>> sieve._list
array('l', [2, 3, 5, 7, 11, 13, 17, 19, 23])
"""
# data shared (and updated) by all Sieve instances
def __init__(self):
self._n = 6
self._list = _aset(2, 3, 5, 7, 11, 13) # primes
self._tlist = _aset(0, 1, 1, 2, 2, 4) # totient
self._mlist = _aset(0, 1, -1, -1, 0, -1) # mobius
assert all(len(i) == self._n for i in (self._list, self._tlist, self._mlist))
def __repr__(self):
return ("<%s sieve (%i): %i, %i, %i, ... %i, %i\n"
"%s sieve (%i): %i, %i, %i, ... %i, %i\n"
"%s sieve (%i): %i, %i, %i, ... %i, %i>") % (
'prime', len(self._list),
self._list[0], self._list[1], self._list[2],
self._list[-2], self._list[-1],
'totient', len(self._tlist),
self._tlist[0], self._tlist[1],
self._tlist[2], self._tlist[-2], self._tlist[-1],
'mobius', len(self._mlist),
self._mlist[0], self._mlist[1],
self._mlist[2], self._mlist[-2], self._mlist[-1])
def _reset(self, prime=None, totient=None, mobius=None):
"""Reset all caches (default). To reset one or more set the
desired keyword to True."""
if all(i is None for i in (prime, totient, mobius)):
prime = totient = mobius = True
if prime:
self._list = self._list[:self._n]
if totient:
self._tlist = self._tlist[:self._n]
if mobius:
self._mlist = self._mlist[:self._n]
def extend(self, n):
"""Grow the sieve to cover all primes <= n (a real number).
Examples
========
>>> from sympy import sieve
>>> sieve._reset() # this line for doctest only
>>> sieve.extend(30)
>>> sieve[10] == 29
True
"""
n = int(n)
if n <= self._list[-1]:
return
# We need to sieve against all bases up to sqrt(n).
# This is a recursive call that will do nothing if there are enough
# known bases already.
maxbase = int(n**0.5) + 1
self.extend(maxbase)
# Create a new sieve starting from sqrt(n)
begin = self._list[-1] + 1
newsieve = _arange(begin, n + 1)
# Now eliminate all multiples of primes in [2, sqrt(n)]
for p in self.primerange(2, maxbase):
# Start counting at a multiple of p, offsetting
# the index to account for the new sieve's base index
startindex = (-begin) % p
for i in range(startindex, len(newsieve), p):
newsieve[i] = 0
# Merge the sieves
self._list += _array('l', [x for x in newsieve if x])
def extend_to_no(self, i):
"""Extend to include the ith prime number.
Parameters
==========
i : integer
Examples
========
>>> from sympy import sieve
>>> sieve._reset() # this line for doctest only
>>> sieve.extend_to_no(9)
>>> sieve._list
array('l', [2, 3, 5, 7, 11, 13, 17, 19, 23])
Notes
=====
The list is extended by 50% if it is too short, so it is
likely that it will be longer than requested.
"""
i = as_int(i)
while len(self._list) < i:
self.extend(int(self._list[-1] * 1.5))
def primerange(self, a, b):
"""Generate all prime numbers in the range [a, b).
Examples
========
>>> from sympy import sieve
>>> print([i for i in sieve.primerange(7, 18)])
[7, 11, 13, 17]
"""
from sympy.functions.elementary.integers import ceiling
# wrapping ceiling in as_int will raise an error if there was a problem
# determining whether the expression was exactly an integer or not
a = max(2, as_int(ceiling(a)))
b = as_int(ceiling(b))
if a >= b:
return
self.extend(b)
i = self.search(a)[1]
maxi = len(self._list) + 1
while i < maxi:
p = self._list[i - 1]
if p < b:
yield p
i += 1
else:
return
def totientrange(self, a, b):
"""Generate all totient numbers for the range [a, b).
Examples
========
>>> from sympy import sieve
>>> print([i for i in sieve.totientrange(7, 18)])
[6, 4, 6, 4, 10, 4, 12, 6, 8, 8, 16]
"""
from sympy.functions.elementary.integers import ceiling
# wrapping ceiling in as_int will raise an error if there was a problem
# determining whether the expression was exactly an integer or not
a = max(1, as_int(ceiling(a)))
b = as_int(ceiling(b))
n = len(self._tlist)
if a >= b:
return
elif b <= n:
for i in range(a, b):
yield self._tlist[i]
else:
self._tlist += _arange(n, b)
for i in range(1, n):
ti = self._tlist[i]
startindex = (n + i - 1) // i * i
for j in range(startindex, b, i):
self._tlist[j] -= ti
if i >= a:
yield ti
for i in range(n, b):
ti = self._tlist[i]
for j in range(2 * i, b, i):
self._tlist[j] -= ti
if i >= a:
yield ti
def mobiusrange(self, a, b):
"""Generate all mobius numbers for the range [a, b).
Parameters
==========
a : integer
First number in range
b : integer
First number outside of range
Examples
========
>>> from sympy import sieve
>>> print([i for i in sieve.mobiusrange(7, 18)])
[-1, 0, 0, 1, -1, 0, -1, 1, 1, 0, -1]
"""
from sympy.functions.elementary.integers import ceiling
# wrapping ceiling in as_int will raise an error if there was a problem
# determining whether the expression was exactly an integer or not
a = max(1, as_int(ceiling(a)))
b = as_int(ceiling(b))
n = len(self._mlist)
if a >= b:
return
elif b <= n:
for i in range(a, b):
yield self._mlist[i]
else:
self._mlist += _azeros(b - n)
for i in range(1, n):
mi = self._mlist[i]
startindex = (n + i - 1) // i * i
for j in range(startindex, b, i):
self._mlist[j] -= mi
if i >= a:
yield mi
for i in range(n, b):
mi = self._mlist[i]
for j in range(2 * i, b, i):
self._mlist[j] -= mi
if i >= a:
yield mi
def search(self, n):
"""Return the indices i, j of the primes that bound n.
If n is prime then i == j.
Although n can be an expression, if ceiling cannot convert
it to an integer then an n error will be raised.
Examples
========
>>> from sympy import sieve
>>> sieve.search(25)
(9, 10)
>>> sieve.search(23)
(9, 9)
"""
from sympy.functions.elementary.integers import ceiling
# wrapping ceiling in as_int will raise an error if there was a problem
# determining whether the expression was exactly an integer or not
test = as_int(ceiling(n))
n = as_int(n)
if n < 2:
raise ValueError("n should be >= 2 but got: %s" % n)
if n > self._list[-1]:
self.extend(n)
b = bisect(self._list, n)
if self._list[b - 1] == test:
return b, b
else:
return b, b + 1
def __contains__(self, n):
try:
n = as_int(n)
assert n >= 2
except (ValueError, AssertionError):
return False
if n % 2 == 0:
return n == 2
a, b = self.search(n)
return a == b
def __getitem__(self, n):
"""Return the nth prime number"""
if isinstance(n, slice):
self.extend_to_no(n.stop)
return self._list[n.start - 1:n.stop - 1:n.step]
else:
n = as_int(n)
self.extend_to_no(n)
return self._list[n - 1]
# Generate a global object for repeated use in trial division etc
sieve = Sieve()
def prime(nth):
""" Return the nth prime, with the primes indexed as prime(1) = 2,
prime(2) = 3, etc.... The nth prime is approximately n*log(n).
Logarithmic integral of x is a pretty nice approximation for number of
primes <= x, i.e.
li(x) ~ pi(x)
In fact, for the numbers we are concerned about( x<1e11 ),
li(x) - pi(x) < 50000
Also,
li(x) > pi(x) can be safely assumed for the numbers which
can be evaluated by this function.
Here, we find the least integer m such that li(m) > n using binary search.
Now pi(m-1) < li(m-1) <= n,
We find pi(m - 1) using primepi function.
Starting from m, we have to find n - pi(m-1) more primes.
For the inputs this implementation can handle, we will have to test
primality for at max about 10**5 numbers, to get our answer.
Examples
========
>>> from sympy import prime
>>> prime(10)
29
>>> prime(1)
2
>>> prime(100000)
1299709
See Also
========
sympy.ntheory.primetest.isprime : Test if n is prime
primerange : Generate all primes in a given range
primepi : Return the number of primes less than or equal to n
References
==========
.. [1] https://en.wikipedia.org/wiki/Prime_number_theorem#Table_of_.CF.80.28x.29.2C_x_.2F_log_x.2C_and_li.28x.29
.. [2] https://en.wikipedia.org/wiki/Prime_number_theorem#Approximations_for_the_nth_prime_number
.. [3] https://en.wikipedia.org/wiki/Skewes%27_number
"""
n = as_int(nth)
if n < 1:
raise ValueError("nth must be a positive integer; prime(1) == 2")
if n <= len(sieve._list):
return sieve[n]
from sympy.functions.special.error_functions import li
from sympy.functions.elementary.exponential import log
a = 2 # Lower bound for binary search
b = int(n*(log(n) + log(log(n)))) # Upper bound for the search.
while a < b:
mid = (a + b) >> 1
if li(mid) > n:
b = mid
else:
a = mid + 1
n_primes = primepi(a - 1)
while n_primes < n:
if isprime(a):
n_primes += 1
a += 1
return a - 1
class primepi(Function):
""" Represents the prime counting function pi(n) = the number
of prime numbers less than or equal to n.
Algorithm Description:
In sieve method, we remove all multiples of prime p
except p itself.
Let phi(i,j) be the number of integers 2 <= k <= i
which remain after sieving from primes less than
or equal to j.
Clearly, pi(n) = phi(n, sqrt(n))
If j is not a prime,
phi(i,j) = phi(i, j - 1)
if j is a prime,
We remove all numbers(except j) whose
smallest prime factor is j.
Let x= j*a be such a number, where 2 <= a<= i / j
Now, after sieving from primes <= j - 1,
a must remain
(because x, and hence a has no prime factor <= j - 1)
Clearly, there are phi(i / j, j - 1) such a
which remain on sieving from primes <= j - 1
Now, if a is a prime less than equal to j - 1,
x= j*a has smallest prime factor = a, and
has already been removed(by sieving from a).
So, we don't need to remove it again.
(Note: there will be pi(j - 1) such x)
Thus, number of x, that will be removed are:
phi(i / j, j - 1) - phi(j - 1, j - 1)
(Note that pi(j - 1) = phi(j - 1, j - 1))
=> phi(i,j) = phi(i, j - 1) - phi(i / j, j - 1) + phi(j - 1, j - 1)
So,following recursion is used and implemented as dp:
phi(a, b) = phi(a, b - 1), if b is not a prime
phi(a, b) = phi(a, b-1)-phi(a / b, b-1) + phi(b-1, b-1), if b is prime
Clearly a is always of the form floor(n / k),
which can take at most 2*sqrt(n) values.
Two arrays arr1,arr2 are maintained
arr1[i] = phi(i, j),
arr2[i] = phi(n // i, j)
Finally the answer is arr2[1]
Examples
========
>>> from sympy import primepi
>>> primepi(25)
9
See Also
========
sympy.ntheory.primetest.isprime : Test if n is prime
primerange : Generate all primes in a given range
prime : Return the nth prime
"""
@classmethod
def eval(cls, n):
if n is S.Infinity:
return S.Infinity
if n is S.NegativeInfinity:
return S.Zero
try:
n = int(n)
except TypeError:
if n.is_real == False or n is S.NaN:
raise ValueError("n must be real")
return
if n < 2:
return S.Zero
if n <= sieve._list[-1]:
return S(sieve.search(n)[0])
lim = int(n ** 0.5)
lim -= 1
lim = max(lim, 0)
while lim * lim <= n:
lim += 1
lim -= 1
arr1 = [0] * (lim + 1)
arr2 = [0] * (lim + 1)
for i in range(1, lim + 1):
arr1[i] = i - 1
arr2[i] = n // i - 1
for i in range(2, lim + 1):
# Presently, arr1[k]=phi(k,i - 1),
# arr2[k] = phi(n // k,i - 1)
if arr1[i] == arr1[i - 1]:
continue
p = arr1[i - 1]
for j in range(1, min(n // (i * i), lim) + 1):
st = i * j
if st <= lim:
arr2[j] -= arr2[st] - p
else:
arr2[j] -= arr1[n // st] - p
lim2 = min(lim, i * i - 1)
for j in range(lim, lim2, -1):
arr1[j] -= arr1[j // i] - p
return S(arr2[1])
def nextprime(n, ith=1):
""" Return the ith prime greater than n.
i must be an integer.
Notes
=====
Potential primes are located at 6*j +/- 1. This
property is used during searching.
>>> from sympy import nextprime
>>> [(i, nextprime(i)) for i in range(10, 15)]
[(10, 11), (11, 13), (12, 13), (13, 17), (14, 17)]
>>> nextprime(2, ith=2) # the 2nd prime after 2
5
See Also
========
prevprime : Return the largest prime smaller than n
primerange : Generate all primes in a given range
"""
n = int(n)
i = as_int(ith)
if i > 1:
pr = n
j = 1
while 1:
pr = nextprime(pr)
j += 1
if j > i:
break
return pr
if n < 2:
return 2
if n < 7:
return {2: 3, 3: 5, 4: 5, 5: 7, 6: 7}[n]
if n <= sieve._list[-2]:
l, u = sieve.search(n)
if l == u:
return sieve[u + 1]
else:
return sieve[u]
nn = 6*(n//6)
if nn == n:
n += 1
if isprime(n):
return n
n += 4
elif n - nn == 5:
n += 2
if isprime(n):
return n
n += 4
else:
n = nn + 5
while 1:
if isprime(n):
return n
n += 2
if isprime(n):
return n
n += 4
def prevprime(n):
""" Return the largest prime smaller than n.
Notes
=====
Potential primes are located at 6*j +/- 1. This
property is used during searching.
>>> from sympy import prevprime
>>> [(i, prevprime(i)) for i in range(10, 15)]
[(10, 7), (11, 7), (12, 11), (13, 11), (14, 13)]
See Also
========
nextprime : Return the ith prime greater than n
primerange : Generates all primes in a given range
"""
from sympy.functions.elementary.integers import ceiling
# wrapping ceiling in as_int will raise an error if there was a problem
# determining whether the expression was exactly an integer or not
n = as_int(ceiling(n))
if n < 3:
raise ValueError("no preceding primes")
if n < 8:
return {3: 2, 4: 3, 5: 3, 6: 5, 7: 5}[n]
if n <= sieve._list[-1]:
l, u = sieve.search(n)
if l == u:
return sieve[l-1]
else:
return sieve[l]
nn = 6*(n//6)
if n - nn <= 1:
n = nn - 1
if isprime(n):
return n
n -= 4
else:
n = nn + 1
while 1:
if isprime(n):
return n
n -= 2
if isprime(n):
return n
n -= 4
def primerange(a, b):
""" Generate a list of all prime numbers in the range [a, b).
If the range exists in the default sieve, the values will
be returned from there; otherwise values will be returned
but will not modify the sieve.
Examples
========
>>> from sympy import primerange, sieve
>>> print([i for i in primerange(1, 30)])
[2, 3, 5, 7, 11, 13, 17, 19, 23, 29]
The Sieve method, primerange, is generally faster but it will
occupy more memory as the sieve stores values. The default
instance of Sieve, named sieve, can be used:
>>> list(sieve.primerange(1, 30))
[2, 3, 5, 7, 11, 13, 17, 19, 23, 29]
Notes
=====
Some famous conjectures about the occurrence of primes in a given
range are [1]:
- Twin primes: though often not, the following will give 2 primes
an infinite number of times:
primerange(6*n - 1, 6*n + 2)
- Legendre's: the following always yields at least one prime
primerange(n**2, (n+1)**2+1)
- Bertrand's (proven): there is always a prime in the range
primerange(n, 2*n)
- Brocard's: there are at least four primes in the range
primerange(prime(n)**2, prime(n+1)**2)
The average gap between primes is log(n) [2]; the gap between
primes can be arbitrarily large since sequences of composite
numbers are arbitrarily large, e.g. the numbers in the sequence
n! + 2, n! + 3 ... n! + n are all composite.
See Also
========
nextprime : Return the ith prime greater than n
prevprime : Return the largest prime smaller than n
randprime : Returns a random prime in a given range
primorial : Returns the product of primes based on condition
Sieve.primerange : return range from already computed primes
or extend the sieve to contain the requested
range.
References
==========
.. [1] https://en.wikipedia.org/wiki/Prime_number
.. [2] http://primes.utm.edu/notes/gaps.html
"""
from sympy.functions.elementary.integers import ceiling
if a >= b:
return
# if we already have the range, return it
if b <= sieve._list[-1]:
for i in sieve.primerange(a, b):
yield i
return
# otherwise compute, without storing, the desired range.
# wrapping ceiling in as_int will raise an error if there was a problem
# determining whether the expression was exactly an integer or not
a = as_int(ceiling(a)) - 1
b = as_int(ceiling(b))
while 1:
a = nextprime(a)
if a < b:
yield a
else:
return
def randprime(a, b):
""" Return a random prime number in the range [a, b).
Bertrand's postulate assures that
randprime(a, 2*a) will always succeed for a > 1.
Examples
========
>>> from sympy import randprime, isprime
>>> randprime(1, 30) #doctest: +SKIP
13
>>> isprime(randprime(1, 30))
True
See Also
========
primerange : Generate all primes in a given range
References
==========
.. [1] https://en.wikipedia.org/wiki/Bertrand's_postulate
"""
if a >= b:
return
a, b = map(int, (a, b))
n = random.randint(a - 1, b)
p = nextprime(n)
if p >= b:
p = prevprime(b)
if p < a:
raise ValueError("no primes exist in the specified range")
return p
def primorial(n, nth=True):
"""
Returns the product of the first n primes (default) or
the primes less than or equal to n (when ``nth=False``).
Examples
========
>>> from sympy.ntheory.generate import primorial, randprime, primerange
>>> from sympy import factorint, Mul, primefactors, sqrt
>>> primorial(4) # the first 4 primes are 2, 3, 5, 7
210
>>> primorial(4, nth=False) # primes <= 4 are 2 and 3
6
>>> primorial(1)
2
>>> primorial(1, nth=False)
1
>>> primorial(sqrt(101), nth=False)
210
One can argue that the primes are infinite since if you take
a set of primes and multiply them together (e.g. the primorial) and
then add or subtract 1, the result cannot be divided by any of the
original factors, hence either 1 or more new primes must divide this
product of primes.
In this case, the number itself is a new prime:
>>> factorint(primorial(4) + 1)
{211: 1}
In this case two new primes are the factors:
>>> factorint(primorial(4) - 1)
{11: 1, 19: 1}
Here, some primes smaller and larger than the primes multiplied together
are obtained:
>>> p = list(primerange(10, 20))
>>> sorted(set(primefactors(Mul(*p) + 1)).difference(set(p)))
[2, 5, 31, 149]
See Also
========
primerange : Generate all primes in a given range
"""
if nth:
n = as_int(n)
else:
n = int(n)
if n < 1:
raise ValueError("primorial argument must be >= 1")
p = 1
if nth:
for i in range(1, n + 1):
p *= prime(i)
else:
for i in primerange(2, n + 1):
p *= i
return p
def cycle_length(f, x0, nmax=None, values=False):
"""For a given iterated sequence, return a generator that gives
the length of the iterated cycle (lambda) and the length of terms
before the cycle begins (mu); if ``values`` is True then the
terms of the sequence will be returned instead. The sequence is
started with value ``x0``.
Note: more than the first lambda + mu terms may be returned and this
is the cost of cycle detection with Brent's method; there are, however,
generally less terms calculated than would have been calculated if the
proper ending point were determined, e.g. by using Floyd's method.
>>> from sympy.ntheory.generate import cycle_length
This will yield successive values of i <-- func(i):
>>> def iter(func, i):
... while 1:
... ii = func(i)
... yield ii
... i = ii
...
A function is defined:
>>> func = lambda i: (i**2 + 1) % 51
and given a seed of 4 and the mu and lambda terms calculated:
>>> next(cycle_length(func, 4))
(6, 2)
We can see what is meant by looking at the output:
>>> n = cycle_length(func, 4, values=True)
>>> list(ni for ni in n)
[17, 35, 2, 5, 26, 14, 44, 50, 2, 5, 26, 14]
There are 6 repeating values after the first 2.
If a sequence is suspected of being longer than you might wish, ``nmax``
can be used to exit early (and mu will be returned as None):
>>> next(cycle_length(func, 4, nmax = 4))
(4, None)
>>> [ni for ni in cycle_length(func, 4, nmax = 4, values=True)]
[17, 35, 2, 5]
Code modified from:
https://en.wikipedia.org/wiki/Cycle_detection.
"""
nmax = int(nmax or 0)
# main phase: search successive powers of two
power = lam = 1
tortoise, hare = x0, f(x0) # f(x0) is the element/node next to x0.
i = 0
while tortoise != hare and (not nmax or i < nmax):
i += 1
if power == lam: # time to start a new power of two?
tortoise = hare
power *= 2
lam = 0
if values:
yield hare
hare = f(hare)
lam += 1
if nmax and i == nmax:
if values:
return
else:
yield nmax, None
return
if not values:
# Find the position of the first repetition of length lambda
mu = 0
tortoise = hare = x0
for i in range(lam):
hare = f(hare)
while tortoise != hare:
tortoise = f(tortoise)
hare = f(hare)
mu += 1
if mu:
mu -= 1
yield lam, mu
def composite(nth):
""" Return the nth composite number, with the composite numbers indexed as
composite(1) = 4, composite(2) = 6, etc....
Examples
========
>>> from sympy import composite
>>> composite(36)
52
>>> composite(1)
4
>>> composite(17737)
20000
See Also
========
sympy.ntheory.primetest.isprime : Test if n is prime
primerange : Generate all primes in a given range
primepi : Return the number of primes less than or equal to n
prime : Return the nth prime
compositepi : Return the number of positive composite numbers less than or equal to n
"""
n = as_int(nth)
if n < 1:
raise ValueError("nth must be a positive integer; composite(1) == 4")
composite_arr = [4, 6, 8, 9, 10, 12, 14, 15, 16, 18]
if n <= 10:
return composite_arr[n - 1]
a, b = 4, sieve._list[-1]
if n <= b - primepi(b) - 1:
while a < b - 1:
mid = (a + b) >> 1
if mid - primepi(mid) - 1 > n:
b = mid
else:
a = mid
if isprime(a):
a -= 1
return a
from sympy.functions.special.error_functions import li
from sympy.functions.elementary.exponential import log
a = 4 # Lower bound for binary search
b = int(n*(log(n) + log(log(n)))) # Upper bound for the search.
while a < b:
mid = (a + b) >> 1
if mid - li(mid) - 1 > n:
b = mid
else:
a = mid + 1
n_composites = a - primepi(a) - 1
while n_composites > n:
if not isprime(a):
n_composites -= 1
a -= 1
if isprime(a):
a -= 1
return a
def compositepi(n):
""" Return the number of positive composite numbers less than or equal to n.
The first positive composite is 4, i.e. compositepi(4) = 1.
Examples
========
>>> from sympy import compositepi
>>> compositepi(25)
15
>>> compositepi(1000)
831
See Also
========
sympy.ntheory.primetest.isprime : Test if n is prime
primerange : Generate all primes in a given range
prime : Return the nth prime
primepi : Return the number of primes less than or equal to n
composite : Return the nth composite number
"""
n = int(n)
if n < 4:
return 0
return n - primepi(n) - 1
|
5aac60bd2ad5a095970d265e2f2a1f44525893dccec5405c3516c0c2267f0914
|
# -*- coding: utf-8 -*-
from __future__ import print_function, division
from sympy.core.compatibility import as_int, range
from sympy.core.function import Function
from sympy.core.numbers import igcd, igcdex, mod_inverse
from sympy.core.power import isqrt
from sympy.core.singleton import S
from .primetest import isprime
from .factor_ import factorint, trailing, totient, multiplicity
from random import randint, Random
def n_order(a, n):
"""Returns the order of ``a`` modulo ``n``.
The order of ``a`` modulo ``n`` is the smallest integer
``k`` such that ``a**k`` leaves a remainder of 1 with ``n``.
Examples
========
>>> from sympy.ntheory import n_order
>>> n_order(3, 7)
6
>>> n_order(4, 7)
3
"""
from collections import defaultdict
a, n = as_int(a), as_int(n)
if igcd(a, n) != 1:
raise ValueError("The two numbers should be relatively prime")
factors = defaultdict(int)
f = factorint(n)
for px, kx in f.items():
if kx > 1:
factors[px] += kx - 1
fpx = factorint(px - 1)
for py, ky in fpx.items():
factors[py] += ky
group_order = 1
for px, kx in factors.items():
group_order *= px**kx
order = 1
if a > n:
a = a % n
for p, e in factors.items():
exponent = group_order
for f in range(e + 1):
if pow(a, exponent, n) != 1:
order *= p ** (e - f + 1)
break
exponent = exponent // p
return order
def _primitive_root_prime_iter(p):
"""
Generates the primitive roots for a prime ``p``
Examples
========
>>> from sympy.ntheory.residue_ntheory import _primitive_root_prime_iter
>>> list(_primitive_root_prime_iter(19))
[2, 3, 10, 13, 14, 15]
References
==========
.. [1] W. Stein "Elementary Number Theory" (2011), page 44
"""
# it is assumed that p is an int
v = [(p - 1) // i for i in factorint(p - 1).keys()]
a = 2
while a < p:
for pw in v:
# a TypeError below may indicate that p was not an int
if pow(a, pw, p) == 1:
break
else:
yield a
a += 1
def primitive_root(p):
"""
Returns the smallest primitive root or None
Parameters
==========
p : positive integer
Examples
========
>>> from sympy.ntheory.residue_ntheory import primitive_root
>>> primitive_root(19)
2
References
==========
.. [1] W. Stein "Elementary Number Theory" (2011), page 44
.. [2] P. Hackman "Elementary Number Theory" (2009), Chapter C
"""
p = as_int(p)
if p < 1:
raise ValueError('p is required to be positive')
if p <= 2:
return 1
f = factorint(p)
if len(f) > 2:
return None
if len(f) == 2:
if 2 not in f or f[2] > 1:
return None
# case p = 2*p1**k, p1 prime
for p1, e1 in f.items():
if p1 != 2:
break
i = 1
while i < p:
i += 2
if i % p1 == 0:
continue
if is_primitive_root(i, p):
return i
else:
if 2 in f:
if p == 4:
return 3
return None
p1, n = list(f.items())[0]
if n > 1:
# see Ref [2], page 81
g = primitive_root(p1)
if is_primitive_root(g, p1**2):
return g
else:
for i in range(2, g + p1 + 1):
if igcd(i, p) == 1 and is_primitive_root(i, p):
return i
return next(_primitive_root_prime_iter(p))
def is_primitive_root(a, p):
"""
Returns True if ``a`` is a primitive root of ``p``
``a`` is said to be the primitive root of ``p`` if gcd(a, p) == 1 and
totient(p) is the smallest positive number s.t.
a**totient(p) cong 1 mod(p)
Examples
========
>>> from sympy.ntheory import is_primitive_root, n_order, totient
>>> is_primitive_root(3, 10)
True
>>> is_primitive_root(9, 10)
False
>>> n_order(3, 10) == totient(10)
True
>>> n_order(9, 10) == totient(10)
False
"""
a, p = as_int(a), as_int(p)
if igcd(a, p) != 1:
raise ValueError("The two numbers should be relatively prime")
if a > p:
a = a % p
return n_order(a, p) == totient(p)
def _sqrt_mod_tonelli_shanks(a, p):
"""
Returns the square root in the case of ``p`` prime with ``p == 1 (mod 8)``
References
==========
.. [1] R. Crandall and C. Pomerance "Prime Numbers", 2nt Ed., page 101
"""
s = trailing(p - 1)
t = p >> s
# find a non-quadratic residue
while 1:
d = randint(2, p - 1)
r = legendre_symbol(d, p)
if r == -1:
break
#assert legendre_symbol(d, p) == -1
A = pow(a, t, p)
D = pow(d, t, p)
m = 0
for i in range(s):
adm = A*pow(D, m, p) % p
adm = pow(adm, 2**(s - 1 - i), p)
if adm % p == p - 1:
m += 2**i
#assert A*pow(D, m, p) % p == 1
x = pow(a, (t + 1)//2, p)*pow(D, m//2, p) % p
return x
def sqrt_mod(a, p, all_roots=False):
"""
Find a root of ``x**2 = a mod p``
Parameters
==========
a : integer
p : positive integer
all_roots : if True the list of roots is returned or None
Notes
=====
If there is no root it is returned None; else the returned root
is less or equal to ``p // 2``; in general is not the smallest one.
It is returned ``p // 2`` only if it is the only root.
Use ``all_roots`` only when it is expected that all the roots fit
in memory; otherwise use ``sqrt_mod_iter``.
Examples
========
>>> from sympy.ntheory import sqrt_mod
>>> sqrt_mod(11, 43)
21
>>> sqrt_mod(17, 32, True)
[7, 9, 23, 25]
"""
if all_roots:
return sorted(list(sqrt_mod_iter(a, p)))
try:
p = abs(as_int(p))
it = sqrt_mod_iter(a, p)
r = next(it)
if r > p // 2:
return p - r
elif r < p // 2:
return r
else:
try:
r = next(it)
if r > p // 2:
return p - r
except StopIteration:
pass
return r
except StopIteration:
return None
def _product(*iters):
"""
Cartesian product generator
Notes
=====
Unlike itertools.product, it works also with iterables which do not fit
in memory. See http://bugs.python.org/issue10109
Author: Fernando Sumudu
with small changes
"""
import itertools
inf_iters = tuple(itertools.cycle(enumerate(it)) for it in iters)
num_iters = len(inf_iters)
cur_val = [None]*num_iters
first_v = True
while True:
i, p = 0, num_iters
while p and not i:
p -= 1
i, cur_val[p] = next(inf_iters[p])
if not p and not i:
if first_v:
first_v = False
else:
break
yield cur_val
def sqrt_mod_iter(a, p, domain=int):
"""
Iterate over solutions to ``x**2 = a mod p``
Parameters
==========
a : integer
p : positive integer
domain : integer domain, ``int``, ``ZZ`` or ``Integer``
Examples
========
>>> from sympy.ntheory.residue_ntheory import sqrt_mod_iter
>>> list(sqrt_mod_iter(11, 43))
[21, 22]
"""
from sympy.polys.galoistools import gf_crt1, gf_crt2
from sympy.polys.domains import ZZ
a, p = as_int(a), abs(as_int(p))
if isprime(p):
a = a % p
if a == 0:
res = _sqrt_mod1(a, p, 1)
else:
res = _sqrt_mod_prime_power(a, p, 1)
if res:
if domain is ZZ:
for x in res:
yield x
else:
for x in res:
yield domain(x)
else:
f = factorint(p)
v = []
pv = []
for px, ex in f.items():
if a % px == 0:
rx = _sqrt_mod1(a, px, ex)
if not rx:
return
else:
rx = _sqrt_mod_prime_power(a, px, ex)
if not rx:
return
v.append(rx)
pv.append(px**ex)
mm, e, s = gf_crt1(pv, ZZ)
if domain is ZZ:
for vx in _product(*v):
r = gf_crt2(vx, pv, mm, e, s, ZZ)
yield r
else:
for vx in _product(*v):
r = gf_crt2(vx, pv, mm, e, s, ZZ)
yield domain(r)
def _sqrt_mod_prime_power(a, p, k):
"""
Find the solutions to ``x**2 = a mod p**k`` when ``a % p != 0``
Parameters
==========
a : integer
p : prime number
k : positive integer
Examples
========
>>> from sympy.ntheory.residue_ntheory import _sqrt_mod_prime_power
>>> _sqrt_mod_prime_power(11, 43, 1)
[21, 22]
References
==========
.. [1] P. Hackman "Elementary Number Theory" (2009), page 160
.. [2] http://www.numbertheory.org/php/squareroot.html
.. [3] [Gathen99]_
"""
from sympy.core.numbers import igcdex
from sympy.polys.domains import ZZ
pk = p**k
a = a % pk
if k == 1:
if p == 2:
return [ZZ(a)]
if not is_quad_residue(a, p):
return None
if p % 4 == 3:
res = pow(a, (p + 1) // 4, p)
elif p % 8 == 5:
sign = pow(a, (p - 1) // 4, p)
if sign == 1:
res = pow(a, (p + 3) // 8, p)
else:
b = pow(4*a, (p - 5) // 8, p)
x = (2*a*b) % p
if pow(x, 2, p) == a:
res = x
else:
res = _sqrt_mod_tonelli_shanks(a, p)
# ``_sqrt_mod_tonelli_shanks(a, p)`` is not deterministic;
# sort to get always the same result
return sorted([ZZ(res), ZZ(p - res)])
if k > 1:
# see Ref.[2]
if p == 2:
if a % 8 != 1:
return None
if k <= 3:
s = set()
for i in range(0, pk, 4):
s.add(1 + i)
s.add(-1 + i)
return list(s)
# according to Ref.[2] for k > 2 there are two solutions
# (mod 2**k-1), that is four solutions (mod 2**k), which can be
# obtained from the roots of x**2 = 0 (mod 8)
rv = [ZZ(1), ZZ(3), ZZ(5), ZZ(7)]
# hensel lift them to solutions of x**2 = 0 (mod 2**k)
# if r**2 - a = 0 mod 2**nx but not mod 2**(nx+1)
# then r + 2**(nx - 1) is a root mod 2**(nx+1)
n = 3
res = []
for r in rv:
nx = n
while nx < k:
r1 = (r**2 - a) >> nx
if r1 % 2:
r = r + (1 << (nx - 1))
#assert (r**2 - a)% (1 << (nx + 1)) == 0
nx += 1
if r not in res:
res.append(r)
x = r + (1 << (k - 1))
#assert (x**2 - a) % pk == 0
if x < (1 << nx) and x not in res:
if (x**2 - a) % pk == 0:
res.append(x)
return res
rv = _sqrt_mod_prime_power(a, p, 1)
if not rv:
return None
r = rv[0]
fr = r**2 - a
# hensel lifting with Newton iteration, see Ref.[3] chapter 9
# with f(x) = x**2 - a; one has f'(a) != 0 (mod p) for p != 2
n = 1
px = p
while 1:
n1 = n
n1 *= 2
if n1 > k:
break
n = n1
px = px**2
frinv = igcdex(2*r, px)[0]
r = (r - fr*frinv) % px
fr = r**2 - a
if n < k:
px = p**k
frinv = igcdex(2*r, px)[0]
r = (r - fr*frinv) % px
return [r, px - r]
def _sqrt_mod1(a, p, n):
"""
Find solution to ``x**2 == a mod p**n`` when ``a % p == 0``
see http://www.numbertheory.org/php/squareroot.html
"""
pn = p**n
a = a % pn
if a == 0:
# case gcd(a, p**k) = p**n
m = n // 2
if n % 2 == 1:
pm1 = p**(m + 1)
def _iter0a():
i = 0
while i < pn:
yield i
i += pm1
return _iter0a()
else:
pm = p**m
def _iter0b():
i = 0
while i < pn:
yield i
i += pm
return _iter0b()
# case gcd(a, p**k) = p**r, r < n
f = factorint(a)
r = f[p]
if r % 2 == 1:
return None
m = r // 2
a1 = a >> r
if p == 2:
if n - r == 1:
pnm1 = 1 << (n - m + 1)
pm1 = 1 << (m + 1)
def _iter1():
k = 1 << (m + 2)
i = 1 << m
while i < pnm1:
j = i
while j < pn:
yield j
j += k
i += pm1
return _iter1()
if n - r == 2:
res = _sqrt_mod_prime_power(a1, p, n - r)
if res is None:
return None
pnm = 1 << (n - m)
def _iter2():
s = set()
for r in res:
i = 0
while i < pn:
x = (r << m) + i
if x not in s:
s.add(x)
yield x
i += pnm
return _iter2()
if n - r > 2:
res = _sqrt_mod_prime_power(a1, p, n - r)
if res is None:
return None
pnm1 = 1 << (n - m - 1)
def _iter3():
s = set()
for r in res:
i = 0
while i < pn:
x = ((r << m) + i) % pn
if x not in s:
s.add(x)
yield x
i += pnm1
return _iter3()
else:
m = r // 2
a1 = a // p**r
res1 = _sqrt_mod_prime_power(a1, p, n - r)
if res1 is None:
return None
pm = p**m
pnr = p**(n-r)
pnm = p**(n-m)
def _iter4():
s = set()
pm = p**m
for rx in res1:
i = 0
while i < pnm:
x = ((rx + i) % pn)
if x not in s:
s.add(x)
yield x*pm
i += pnr
return _iter4()
def is_quad_residue(a, p):
"""
Returns True if ``a`` (mod ``p``) is in the set of squares mod ``p``,
i.e a % p in set([i**2 % p for i in range(p)]). If ``p`` is an odd
prime, an iterative method is used to make the determination:
>>> from sympy.ntheory import is_quad_residue
>>> sorted(set([i**2 % 7 for i in range(7)]))
[0, 1, 2, 4]
>>> [j for j in range(7) if is_quad_residue(j, 7)]
[0, 1, 2, 4]
See Also
========
legendre_symbol, jacobi_symbol
"""
a, p = as_int(a), as_int(p)
if p < 1:
raise ValueError('p must be > 0')
if a >= p or a < 0:
a = a % p
if a < 2 or p < 3:
return True
if not isprime(p):
if p % 2 and jacobi_symbol(a, p) == -1:
return False
r = sqrt_mod(a, p)
if r is None:
return False
else:
return True
return pow(a, (p - 1) // 2, p) == 1
def is_nthpow_residue(a, n, m):
"""
Returns True if ``x**n == a (mod m)`` has solutions.
References
==========
.. [1] P. Hackman "Elementary Number Theory" (2009), page 76
"""
a, n, m = as_int(a), as_int(n), as_int(m)
if m <= 0:
raise ValueError('m must be > 0')
if n < 0:
raise ValueError('n must be >= 0')
if a < 0:
raise ValueError('a must be >= 0')
if n == 0:
if m == 1:
return False
return a == 1
if n == 1:
return True
if n == 2:
return is_quad_residue(a, m)
return _is_nthpow_residue_bign(a, n, m)
def _is_nthpow_residue_bign(a, n, m):
"""Returns True if ``x**n == a (mod m)`` has solutions for n > 2."""
# assert n > 2
# assert a > 0 and m > 0
if primitive_root(m) is None:
# assert m >= 8
for prime, power in factorint(m).items():
if not _is_nthpow_residue_bign_prime_power(a, n, prime, power):
return False
return True
f = totient(m)
k = f // igcd(f, n)
return pow(a, k, m) == 1
def _is_nthpow_residue_bign_prime_power(a, n, p, k):
"""Returns True/False if a solution for ``x**n == a (mod(p**k))``
does/doesn't exist."""
# assert a > 0
# assert n > 2
# assert p is prime
# assert k > 0
if a % p:
if p != 2:
return _is_nthpow_residue_bign(a, n, pow(p, k))
if n & 1:
return True
c = trailing(n)
return a % pow(2, min(c + 2, k)) == 1
else:
a %= pow(p, k)
if not a:
return True
mu = multiplicity(p, a)
if mu % n:
return False
pm = pow(p, mu)
return _is_nthpow_residue_bign_prime_power(a//pm, n, p, k - mu)
def _nthroot_mod2(s, q, p):
f = factorint(q)
v = []
for b, e in f.items():
v.extend([b]*e)
for qx in v:
s = _nthroot_mod1(s, qx, p, False)
return s
def _nthroot_mod1(s, q, p, all_roots):
"""
Root of ``x**q = s mod p``, ``p`` prime and ``q`` divides ``p - 1``
References
==========
.. [1] A. M. Johnston "A Generalized qth Root Algorithm"
"""
g = primitive_root(p)
if not isprime(q):
r = _nthroot_mod2(s, q, p)
else:
f = p - 1
assert (p - 1) % q == 0
# determine k
k = 0
while f % q == 0:
k += 1
f = f // q
# find z, x, r1
f1 = igcdex(-f, q)[0] % q
z = f*f1
x = (1 + z) // q
r1 = pow(s, x, p)
s1 = pow(s, f, p)
h = pow(g, f*q, p)
t = discrete_log(p, s1, h)
g2 = pow(g, z*t, p)
g3 = igcdex(g2, p)[0]
r = r1*g3 % p
#assert pow(r, q, p) == s
res = [r]
h = pow(g, (p - 1) // q, p)
#assert pow(h, q, p) == 1
hx = r
for i in range(q - 1):
hx = (hx*h) % p
res.append(hx)
if all_roots:
res.sort()
return res
return min(res)
def nthroot_mod(a, n, p, all_roots=False):
"""
Find the solutions to ``x**n = a mod p``
Parameters
==========
a : integer
n : positive integer
p : positive integer
all_roots : if False returns the smallest root, else the list of roots
Examples
========
>>> from sympy.ntheory.residue_ntheory import nthroot_mod
>>> nthroot_mod(11, 4, 19)
8
>>> nthroot_mod(11, 4, 19, True)
[8, 11]
>>> nthroot_mod(68, 3, 109)
23
"""
from sympy.core.numbers import igcdex
a, n, p = as_int(a), as_int(n), as_int(p)
if n == 2:
return sqrt_mod(a, p, all_roots)
# see Hackman "Elementary Number Theory" (2009), page 76
if not is_nthpow_residue(a, n, p):
return None
if primitive_root(p) == None:
raise NotImplementedError("Not Implemented for m without primitive root")
if (p - 1) % n == 0:
return _nthroot_mod1(a, n, p, all_roots)
# The roots of ``x**n - a = 0 (mod p)`` are roots of
# ``gcd(x**n - a, x**(p - 1) - 1) = 0 (mod p)``
pa = n
pb = p - 1
b = 1
if pa < pb:
a, pa, b, pb = b, pb, a, pa
while pb:
# x**pa - a = 0; x**pb - b = 0
# x**pa - a = x**(q*pb + r) - a = (x**pb)**q * x**r - a =
# b**q * x**r - a; x**r - c = 0; c = b**-q * a mod p
q, r = divmod(pa, pb)
c = pow(b, q, p)
c = igcdex(c, p)[0]
c = (c * a) % p
pa, pb = pb, r
a, b = b, c
if pa == 1:
if all_roots:
res = [a]
else:
res = a
elif pa == 2:
return sqrt_mod(a, p , all_roots)
else:
res = _nthroot_mod1(a, pa, p, all_roots)
return res
def quadratic_residues(p):
"""
Returns the list of quadratic residues.
Examples
========
>>> from sympy.ntheory.residue_ntheory import quadratic_residues
>>> quadratic_residues(7)
[0, 1, 2, 4]
"""
p = as_int(p)
r = set()
for i in range(p // 2 + 1):
r.add(pow(i, 2, p))
return sorted(list(r))
def legendre_symbol(a, p):
r"""
Returns the Legendre symbol `(a / p)`.
For an integer ``a`` and an odd prime ``p``, the Legendre symbol is
defined as
.. math ::
\genfrac(){}{}{a}{p} = \begin{cases}
0 & \text{if } p \text{ divides } a\\
1 & \text{if } a \text{ is a quadratic residue modulo } p\\
-1 & \text{if } a \text{ is a quadratic nonresidue modulo } p
\end{cases}
Parameters
==========
a : integer
p : odd prime
Examples
========
>>> from sympy.ntheory import legendre_symbol
>>> [legendre_symbol(i, 7) for i in range(7)]
[0, 1, 1, -1, 1, -1, -1]
>>> sorted(set([i**2 % 7 for i in range(7)]))
[0, 1, 2, 4]
See Also
========
is_quad_residue, jacobi_symbol
"""
a, p = as_int(a), as_int(p)
if not isprime(p) or p == 2:
raise ValueError("p should be an odd prime")
a = a % p
if not a:
return 0
if is_quad_residue(a, p):
return 1
return -1
def jacobi_symbol(m, n):
r"""
Returns the Jacobi symbol `(m / n)`.
For any integer ``m`` and any positive odd integer ``n`` the Jacobi symbol
is defined as the product of the Legendre symbols corresponding to the
prime factors of ``n``:
.. math ::
\genfrac(){}{}{m}{n} =
\genfrac(){}{}{m}{p^{1}}^{\alpha_1}
\genfrac(){}{}{m}{p^{2}}^{\alpha_2}
...
\genfrac(){}{}{m}{p^{k}}^{\alpha_k}
\text{ where } n =
p_1^{\alpha_1}
p_2^{\alpha_2}
...
p_k^{\alpha_k}
Like the Legendre symbol, if the Jacobi symbol `\genfrac(){}{}{m}{n} = -1`
then ``m`` is a quadratic nonresidue modulo ``n``.
But, unlike the Legendre symbol, if the Jacobi symbol
`\genfrac(){}{}{m}{n} = 1` then ``m`` may or may not be a quadratic residue
modulo ``n``.
Parameters
==========
m : integer
n : odd positive integer
Examples
========
>>> from sympy.ntheory import jacobi_symbol, legendre_symbol
>>> from sympy import Mul, S
>>> jacobi_symbol(45, 77)
-1
>>> jacobi_symbol(60, 121)
1
The relationship between the ``jacobi_symbol`` and ``legendre_symbol`` can
be demonstrated as follows:
>>> L = legendre_symbol
>>> S(45).factors()
{3: 2, 5: 1}
>>> jacobi_symbol(7, 45) == L(7, 3)**2 * L(7, 5)**1
True
See Also
========
is_quad_residue, legendre_symbol
"""
m, n = as_int(m), as_int(n)
if n < 0 or not n % 2:
raise ValueError("n should be an odd positive integer")
if m < 0 or m > n:
m = m % n
if not m:
return int(n == 1)
if n == 1 or m == 1:
return 1
if igcd(m, n) != 1:
return 0
j = 1
if m < 0:
m = -m
if n % 4 == 3:
j = -j
while m != 0:
while m % 2 == 0 and m > 0:
m >>= 1
if n % 8 in [3, 5]:
j = -j
m, n = n, m
if m % 4 == 3 and n % 4 == 3:
j = -j
m %= n
if n != 1:
j = 0
return j
class mobius(Function):
"""
Möbius function maps natural number to {-1, 0, 1}
It is defined as follows:
1) `1` if `n = 1`.
2) `0` if `n` has a squared prime factor.
3) `(-1)^k` if `n` is a square-free positive integer with `k`
number of prime factors.
It is an important multiplicative function in number theory
and combinatorics. It has applications in mathematical series,
algebraic number theory and also physics (Fermion operator has very
concrete realization with Möbius Function model).
Parameters
==========
n : positive integer
Examples
========
>>> from sympy.ntheory import mobius
>>> mobius(13*7)
1
>>> mobius(1)
1
>>> mobius(13*7*5)
-1
>>> mobius(13**2)
0
References
==========
.. [1] https://en.wikipedia.org/wiki/M%C3%B6bius_function
.. [2] Thomas Koshy "Elementary Number Theory with Applications"
"""
@classmethod
def eval(cls, n):
if n.is_integer:
if n.is_positive is not True:
raise ValueError("n should be a positive integer")
else:
raise TypeError("n should be an integer")
if n.is_prime:
return S.NegativeOne
elif n is S.One:
return S.One
elif n.is_Integer:
a = factorint(n)
if any(i > 1 for i in a.values()):
return S.Zero
return S.NegativeOne**len(a)
def _discrete_log_trial_mul(n, a, b, order=None):
"""
Trial multiplication algorithm for computing the discrete logarithm of
``a`` to the base ``b`` modulo ``n``.
The algorithm finds the discrete logarithm using exhaustive search. This
naive method is used as fallback algorithm of ``discrete_log`` when the
group order is very small.
Examples
========
>>> from sympy.ntheory.residue_ntheory import _discrete_log_trial_mul
>>> _discrete_log_trial_mul(41, 15, 7)
3
See Also
========
discrete_log
References
==========
.. [1] "Handbook of applied cryptography", Menezes, A. J., Van, O. P. C., &
Vanstone, S. A. (1997).
"""
a %= n
b %= n
if order is None:
order = n
x = 1
for i in range(order):
if x == a:
return i
x = x * b % n
raise ValueError("Log does not exist")
def _discrete_log_shanks_steps(n, a, b, order=None):
"""
Baby-step giant-step algorithm for computing the discrete logarithm of
``a`` to the base ``b`` modulo ``n``.
The algorithm is a time-memory trade-off of the method of exhaustive
search. It uses `O(sqrt(m))` memory, where `m` is the group order.
Examples
========
>>> from sympy.ntheory.residue_ntheory import _discrete_log_shanks_steps
>>> _discrete_log_shanks_steps(41, 15, 7)
3
See Also
========
discrete_log
References
==========
.. [1] "Handbook of applied cryptography", Menezes, A. J., Van, O. P. C., &
Vanstone, S. A. (1997).
"""
a %= n
b %= n
if order is None:
order = n_order(b, n)
m = isqrt(order) + 1
T = dict()
x = 1
for i in range(m):
T[x] = i
x = x * b % n
z = mod_inverse(b, n)
z = pow(z, m, n)
x = a
for i in range(m):
if x in T:
return i * m + T[x]
x = x * z % n
raise ValueError("Log does not exist")
def _discrete_log_pollard_rho(n, a, b, order=None, retries=10, rseed=None):
"""
Pollard's Rho algorithm for computing the discrete logarithm of ``a`` to
the base ``b`` modulo ``n``.
It is a randomized algorithm with the same expected running time as
``_discrete_log_shanks_steps``, but requires a negligible amount of memory.
Examples
========
>>> from sympy.ntheory.residue_ntheory import _discrete_log_pollard_rho
>>> _discrete_log_pollard_rho(227, 3**7, 3)
7
See Also
========
discrete_log
References
==========
.. [1] "Handbook of applied cryptography", Menezes, A. J., Van, O. P. C., &
Vanstone, S. A. (1997).
"""
a %= n
b %= n
if order is None:
order = n_order(b, n)
prng = Random()
if rseed is not None:
prng.seed(rseed)
for i in range(retries):
aa = prng.randint(1, order - 1)
ba = prng.randint(1, order - 1)
xa = pow(b, aa, n) * pow(a, ba, n) % n
c = xa % 3
if c == 0:
xb = a * xa % n
ab = aa
bb = (ba + 1) % order
elif c == 1:
xb = xa * xa % n
ab = (aa + aa) % order
bb = (ba + ba) % order
else:
xb = b * xa % n
ab = (aa + 1) % order
bb = ba
for j in range(order):
c = xa % 3
if c == 0:
xa = a * xa % n
ba = (ba + 1) % order
elif c == 1:
xa = xa * xa % n
aa = (aa + aa) % order
ba = (ba + ba) % order
else:
xa = b * xa % n
aa = (aa + 1) % order
c = xb % 3
if c == 0:
xb = a * xb % n
bb = (bb + 1) % order
elif c == 1:
xb = xb * xb % n
ab = (ab + ab) % order
bb = (bb + bb) % order
else:
xb = b * xb % n
ab = (ab + 1) % order
c = xb % 3
if c == 0:
xb = a * xb % n
bb = (bb + 1) % order
elif c == 1:
xb = xb * xb % n
ab = (ab + ab) % order
bb = (bb + bb) % order
else:
xb = b * xb % n
ab = (ab + 1) % order
if xa == xb:
r = (ba - bb) % order
if r != 0:
return mod_inverse(r, order) * (ab - aa) % order
break
raise ValueError("Pollard's Rho failed to find logarithm")
def _discrete_log_pohlig_hellman(n, a, b, order=None):
"""
Pohlig-Hellman algorithm for computing the discrete logarithm of ``a`` to
the base ``b`` modulo ``n``.
In order to compute the discrete logarithm, the algorithm takes advantage
of the factorization of the group order. It is more efficient when the
group order factors into many small primes.
Examples
========
>>> from sympy.ntheory.residue_ntheory import _discrete_log_pohlig_hellman
>>> _discrete_log_pohlig_hellman(251, 210, 71)
197
See Also
========
discrete_log
References
==========
.. [1] "Handbook of applied cryptography", Menezes, A. J., Van, O. P. C., &
Vanstone, S. A. (1997).
"""
from .modular import crt
a %= n
b %= n
if order is None:
order = n_order(b, n)
f = factorint(order)
l = [0] * len(f)
for i, (pi, ri) in enumerate(f.items()):
for j in range(ri):
gj = pow(b, l[i], n)
aj = pow(a * mod_inverse(gj, n), order // pi**(j + 1), n)
bj = pow(b, order // pi, n)
cj = discrete_log(n, aj, bj, pi, True)
l[i] += cj * pi**j
d, _ = crt([pi**ri for pi, ri in f.items()], l)
return d
def discrete_log(n, a, b, order=None, prime_order=None):
"""
Compute the discrete logarithm of ``a`` to the base ``b`` modulo ``n``.
This is a recursive function to reduce the discrete logarithm problem in
cyclic groups of composite order to the problem in cyclic groups of prime
order.
It employs different algorithms depending on the problem (subgroup order
size, prime order or not):
* Trial multiplication
* Baby-step giant-step
* Pollard's Rho
* Pohlig-Hellman
Examples
========
>>> from sympy.ntheory import discrete_log
>>> discrete_log(41, 15, 7)
3
References
==========
.. [1] http://mathworld.wolfram.com/DiscreteLogarithm.html
.. [2] "Handbook of applied cryptography", Menezes, A. J., Van, O. P. C., &
Vanstone, S. A. (1997).
"""
n, a, b = as_int(n), as_int(a), as_int(b)
if order is None:
order = n_order(b, n)
if prime_order is None:
prime_order = isprime(order)
if order < 1000:
return _discrete_log_trial_mul(n, a, b, order)
elif prime_order:
if order < 1000000000000:
return _discrete_log_shanks_steps(n, a, b, order)
return _discrete_log_pollard_rho(n, a, b, order)
return _discrete_log_pohlig_hellman(n, a, b, order)
|
b290d6841f18ad065eb2a32ec41ea48b54955e0fc9a7f293bcc1ecb04e13450b
|
from __future__ import print_function, division
from sympy.core.compatibility import as_int, reduce
from sympy.core.mul import prod
from sympy.core.numbers import igcdex, igcd
from sympy.ntheory.primetest import isprime
from sympy.polys.domains import ZZ
from sympy.polys.galoistools import gf_crt, gf_crt1, gf_crt2
def symmetric_residue(a, m):
"""Return the residual mod m such that it is within half of the modulus.
>>> from sympy.ntheory.modular import symmetric_residue
>>> symmetric_residue(1, 6)
1
>>> symmetric_residue(4, 6)
-2
"""
if a <= m // 2:
return a
return a - m
def crt(m, v, symmetric=False, check=True):
r"""Chinese Remainder Theorem.
The moduli in m are assumed to be pairwise coprime. The output
is then an integer f, such that f = v_i mod m_i for each pair out
of v and m. If ``symmetric`` is False a positive integer will be
returned, else \|f\| will be less than or equal to the LCM of the
moduli, and thus f may be negative.
If the moduli are not co-prime the correct result will be returned
if/when the test of the result is found to be incorrect. This result
will be None if there is no solution.
The keyword ``check`` can be set to False if it is known that the moduli
are coprime.
Examples
========
As an example consider a set of residues ``U = [49, 76, 65]``
and a set of moduli ``M = [99, 97, 95]``. Then we have::
>>> from sympy.ntheory.modular import crt, solve_congruence
>>> crt([99, 97, 95], [49, 76, 65])
(639985, 912285)
This is the correct result because::
>>> [639985 % m for m in [99, 97, 95]]
[49, 76, 65]
If the moduli are not co-prime, you may receive an incorrect result
if you use ``check=False``:
>>> crt([12, 6, 17], [3, 4, 2], check=False)
(954, 1224)
>>> [954 % m for m in [12, 6, 17]]
[6, 0, 2]
>>> crt([12, 6, 17], [3, 4, 2]) is None
True
>>> crt([3, 6], [2, 5])
(5, 6)
Note: the order of gf_crt's arguments is reversed relative to crt,
and that solve_congruence takes residue, modulus pairs.
Programmer's note: rather than checking that all pairs of moduli share
no GCD (an O(n**2) test) and rather than factoring all moduli and seeing
that there is no factor in common, a check that the result gives the
indicated residuals is performed -- an O(n) operation.
See Also
========
solve_congruence
sympy.polys.galoistools.gf_crt : low level crt routine used by this routine
"""
if check:
m = list(map(as_int, m))
v = list(map(as_int, v))
result = gf_crt(v, m, ZZ)
mm = prod(m)
if check:
if not all(v % m == result % m for v, m in zip(v, m)):
result = solve_congruence(*list(zip(v, m)),
check=False, symmetric=symmetric)
if result is None:
return result
result, mm = result
if symmetric:
return symmetric_residue(result, mm), mm
return result, mm
def crt1(m):
"""First part of Chinese Remainder Theorem, for multiple application.
Examples
========
>>> from sympy.ntheory.modular import crt1
>>> crt1([18, 42, 6])
(4536, [252, 108, 756], [0, 2, 0])
"""
return gf_crt1(m, ZZ)
def crt2(m, v, mm, e, s, symmetric=False):
"""Second part of Chinese Remainder Theorem, for multiple application.
Examples
========
>>> from sympy.ntheory.modular import crt1, crt2
>>> mm, e, s = crt1([18, 42, 6])
>>> crt2([18, 42, 6], [0, 0, 0], mm, e, s)
(0, 4536)
"""
result = gf_crt2(v, m, mm, e, s, ZZ)
if symmetric:
return symmetric_residue(result, mm), mm
return result, mm
def solve_congruence(*remainder_modulus_pairs, **hint):
"""Compute the integer ``n`` that has the residual ``ai`` when it is
divided by ``mi`` where the ``ai`` and ``mi`` are given as pairs to
this function: ((a1, m1), (a2, m2), ...). If there is no solution,
return None. Otherwise return ``n`` and its modulus.
The ``mi`` values need not be co-prime. If it is known that the moduli are
not co-prime then the hint ``check`` can be set to False (default=True) and
the check for a quicker solution via crt() (valid when the moduli are
co-prime) will be skipped.
If the hint ``symmetric`` is True (default is False), the value of ``n``
will be within 1/2 of the modulus, possibly negative.
Examples
========
>>> from sympy.ntheory.modular import solve_congruence
What number is 2 mod 3, 3 mod 5 and 2 mod 7?
>>> solve_congruence((2, 3), (3, 5), (2, 7))
(23, 105)
>>> [23 % m for m in [3, 5, 7]]
[2, 3, 2]
If you prefer to work with all remainder in one list and
all moduli in another, send the arguments like this:
>>> solve_congruence(*zip((2, 3, 2), (3, 5, 7)))
(23, 105)
The moduli need not be co-prime; in this case there may or
may not be a solution:
>>> solve_congruence((2, 3), (4, 6)) is None
True
>>> solve_congruence((2, 3), (5, 6))
(5, 6)
The symmetric flag will make the result be within 1/2 of the modulus:
>>> solve_congruence((2, 3), (5, 6), symmetric=True)
(-1, 6)
See Also
========
crt : high level routine implementing the Chinese Remainder Theorem
"""
def combine(c1, c2):
"""Return the tuple (a, m) which satisfies the requirement
that n = a + i*m satisfy n = a1 + j*m1 and n = a2 = k*m2.
References
==========
- https://en.wikipedia.org/wiki/Method_of_successive_substitution
"""
a1, m1 = c1
a2, m2 = c2
a, b, c = m1, a2 - a1, m2
g = reduce(igcd, [a, b, c])
a, b, c = [i//g for i in [a, b, c]]
if a != 1:
inv_a, _, g = igcdex(a, c)
if g != 1:
return None
b *= inv_a
a, m = a1 + m1*b, m1*c
return a, m
rm = remainder_modulus_pairs
symmetric = hint.get('symmetric', False)
if hint.get('check', True):
rm = [(as_int(r), as_int(m)) for r, m in rm]
# ignore redundant pairs but raise an error otherwise; also
# make sure that a unique set of bases is sent to gf_crt if
# they are all prime.
#
# The routine will work out less-trivial violations and
# return None, e.g. for the pairs (1,3) and (14,42) there
# is no answer because 14 mod 42 (having a gcd of 14) implies
# (14/2) mod (42/2), (14/7) mod (42/7) and (14/14) mod (42/14)
# which, being 0 mod 3, is inconsistent with 1 mod 3. But to
# preprocess the input beyond checking of another pair with 42
# or 3 as the modulus (for this example) is not necessary.
uniq = {}
for r, m in rm:
r %= m
if m in uniq:
if r != uniq[m]:
return None
continue
uniq[m] = r
rm = [(r, m) for m, r in uniq.items()]
del uniq
# if the moduli are co-prime, the crt will be significantly faster;
# checking all pairs for being co-prime gets to be slow but a prime
# test is a good trade-off
if all(isprime(m) for r, m in rm):
r, m = list(zip(*rm))
return crt(m, r, symmetric=symmetric, check=False)
rv = (0, 1)
for rmi in rm:
rv = combine(rv, rmi)
if rv is None:
break
n, m = rv
n = n % m
else:
if symmetric:
return symmetric_residue(n, m), m
return n, m
|
81ff4ab5e70523af269eb15212a00511073aec2956074150fff600c0ea1174e9
|
from __future__ import print_function, division
from collections import defaultdict
from sympy.core.compatibility import range, as_int
def binomial_coefficients(n):
"""Return a dictionary containing pairs :math:`{(k1,k2) : C_kn}` where
:math:`C_kn` are binomial coefficients and :math:`n=k1+k2`.
Examples
========
>>> from sympy.ntheory import binomial_coefficients
>>> binomial_coefficients(9)
{(0, 9): 1, (1, 8): 9, (2, 7): 36, (3, 6): 84,
(4, 5): 126, (5, 4): 126, (6, 3): 84, (7, 2): 36, (8, 1): 9, (9, 0): 1}
See Also
========
binomial_coefficients_list, multinomial_coefficients
"""
n = as_int(n)
d = {(0, n): 1, (n, 0): 1}
a = 1
for k in range(1, n//2 + 1):
a = (a * (n - k + 1))//k
d[k, n - k] = d[n - k, k] = a
return d
def binomial_coefficients_list(n):
""" Return a list of binomial coefficients as rows of the Pascal's
triangle.
Examples
========
>>> from sympy.ntheory import binomial_coefficients_list
>>> binomial_coefficients_list(9)
[1, 9, 36, 84, 126, 126, 84, 36, 9, 1]
See Also
========
binomial_coefficients, multinomial_coefficients
"""
n = as_int(n)
d = [1] * (n + 1)
a = 1
for k in range(1, n//2 + 1):
a = (a * (n - k + 1))//k
d[k] = d[n - k] = a
return d
def multinomial_coefficients(m, n):
r"""Return a dictionary containing pairs ``{(k1,k2,..,km) : C_kn}``
where ``C_kn`` are multinomial coefficients such that
``n=k1+k2+..+km``.
Examples
========
>>> from sympy.ntheory import multinomial_coefficients
>>> multinomial_coefficients(2, 5) # indirect doctest
{(0, 5): 1, (1, 4): 5, (2, 3): 10, (3, 2): 10, (4, 1): 5, (5, 0): 1}
Notes
=====
The algorithm is based on the following result:
.. math::
\binom{n}{k_1, \ldots, k_m} =
\frac{k_1 + 1}{n - k_1} \sum_{i=2}^m \binom{n}{k_1 + 1, \ldots, k_i - 1, \ldots}
Code contributed to Sage by Yann Laigle-Chapuy, copied with permission
of the author.
See Also
========
binomial_coefficients_list, binomial_coefficients
"""
m = as_int(m)
n = as_int(n)
if not m:
if n:
return {}
return {(): 1}
if m == 2:
return binomial_coefficients(n)
if m >= 2*n and n > 1:
return dict(multinomial_coefficients_iterator(m, n))
t = [n] + [0] * (m - 1)
r = {tuple(t): 1}
if n:
j = 0 # j will be the leftmost nonzero position
else:
j = m
# enumerate tuples in co-lex order
while j < m - 1:
# compute next tuple
tj = t[j]
if j:
t[j] = 0
t[0] = tj
if tj > 1:
t[j + 1] += 1
j = 0
start = 1
v = 0
else:
j += 1
start = j + 1
v = r[tuple(t)]
t[j] += 1
# compute the value
# NB: the initialization of v was done above
for k in range(start, m):
if t[k]:
t[k] -= 1
v += r[tuple(t)]
t[k] += 1
t[0] -= 1
r[tuple(t)] = (v * tj) // (n - t[0])
return r
def multinomial_coefficients_iterator(m, n, _tuple=tuple):
"""multinomial coefficient iterator
This routine has been optimized for `m` large with respect to `n` by taking
advantage of the fact that when the monomial tuples `t` are stripped of
zeros, their coefficient is the same as that of the monomial tuples from
``multinomial_coefficients(n, n)``. Therefore, the latter coefficients are
precomputed to save memory and time.
>>> from sympy.ntheory.multinomial import multinomial_coefficients
>>> m53, m33 = multinomial_coefficients(5,3), multinomial_coefficients(3,3)
>>> m53[(0,0,0,1,2)] == m53[(0,0,1,0,2)] == m53[(1,0,2,0,0)] == m33[(0,1,2)]
True
Examples
========
>>> from sympy.ntheory.multinomial import multinomial_coefficients_iterator
>>> it = multinomial_coefficients_iterator(20,3)
>>> next(it)
((3, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0), 1)
"""
m = as_int(m)
n = as_int(n)
if m < 2*n or n == 1:
mc = multinomial_coefficients(m, n)
for k, v in mc.items():
yield(k, v)
else:
mc = multinomial_coefficients(n, n)
mc1 = {}
for k, v in mc.items():
mc1[_tuple(filter(None, k))] = v
mc = mc1
t = [n] + [0] * (m - 1)
t1 = _tuple(t)
b = _tuple(filter(None, t1))
yield (t1, mc[b])
if n:
j = 0 # j will be the leftmost nonzero position
else:
j = m
# enumerate tuples in co-lex order
while j < m - 1:
# compute next tuple
tj = t[j]
if j:
t[j] = 0
t[0] = tj
if tj > 1:
t[j + 1] += 1
j = 0
else:
j += 1
t[j] += 1
t[0] -= 1
t1 = _tuple(t)
b = _tuple(filter(None, t1))
yield (t1, mc[b])
|
0129f6862281680121f260aa76f1c302f6e31261368674a8939f08c9cdd9126b
|
from __future__ import print_function, division
from sympy import Integer
from sympy.core.compatibility import range
import sympy.polys
import sys
if sys.version_info < (3,5):
from fractions import gcd
else:
from math import gcd
def egyptian_fraction(r, algorithm="Greedy"):
"""
Return the list of denominators of an Egyptian fraction
expansion [1]_ of the said rational `r`.
Parameters
==========
r : Rational
a positive rational number.
algorithm : { "Greedy", "Graham Jewett", "Takenouchi", "Golomb" }, optional
Denotes the algorithm to be used (the default is "Greedy").
Examples
========
>>> from sympy import Rational
>>> from sympy.ntheory.egyptian_fraction import egyptian_fraction
>>> egyptian_fraction(Rational(3, 7))
[3, 11, 231]
>>> egyptian_fraction(Rational(3, 7), "Graham Jewett")
[7, 8, 9, 56, 57, 72, 3192]
>>> egyptian_fraction(Rational(3, 7), "Takenouchi")
[4, 7, 28]
>>> egyptian_fraction(Rational(3, 7), "Golomb")
[3, 15, 35]
>>> egyptian_fraction(Rational(11, 5), "Golomb")
[1, 2, 3, 4, 9, 234, 1118, 2580]
See Also
========
sympy.core.numbers.Rational
Notes
=====
Currently the following algorithms are supported:
1) Greedy Algorithm
Also called the Fibonacci-Sylvester algorithm [2]_.
At each step, extract the largest unit fraction less
than the target and replace the target with the remainder.
It has some distinct properties:
a) Given `p/q` in lowest terms, generates an expansion of maximum
length `p`. Even as the numerators get large, the number of
terms is seldom more than a handful.
b) Uses minimal memory.
c) The terms can blow up (standard examples of this are 5/121 and
31/311). The denominator is at most squared at each step
(doubly-exponential growth) and typically exhibits
singly-exponential growth.
2) Graham Jewett Algorithm
The algorithm suggested by the result of Graham and Jewett.
Note that this has a tendency to blow up: the length of the
resulting expansion is always ``2**(x/gcd(x, y)) - 1``. See [3]_.
3) Takenouchi Algorithm
The algorithm suggested by Takenouchi (1921).
Differs from the Graham-Jewett algorithm only in the handling
of duplicates. See [3]_.
4) Golomb's Algorithm
A method given by Golumb (1962), using modular arithmetic and
inverses. It yields the same results as a method using continued
fractions proposed by Bleicher (1972). See [4]_.
If the given rational is greater than or equal to 1, a greedy algorithm
of summing the harmonic sequence 1/1 + 1/2 + 1/3 + ... is used, taking
all the unit fractions of this sequence until adding one more would be
greater than the given number. This list of denominators is prefixed
to the result from the requested algorithm used on the remainder. For
example, if r is 8/3, using the Greedy algorithm, we get [1, 2, 3, 4,
5, 6, 7, 14, 420], where the beginning of the sequence, [1, 2, 3, 4, 5,
6, 7] is part of the harmonic sequence summing to 363/140, leaving a
remainder of 31/420, which yields [14, 420] by the Greedy algorithm.
The result of egyptian_fraction(Rational(8, 3), "Golomb") is [1, 2, 3,
4, 5, 6, 7, 14, 574, 2788, 6460, 11590, 33062, 113820], and so on.
References
==========
.. [1] https://en.wikipedia.org/wiki/Egyptian_fraction
.. [2] https://en.wikipedia.org/wiki/Greedy_algorithm_for_Egyptian_fractions
.. [3] https://www.ics.uci.edu/~eppstein/numth/egypt/conflict.html
.. [4] http://ami.ektf.hu/uploads/papers/finalpdf/AMI_42_from129to134.pdf
"""
if r <= 0:
raise ValueError("Value must be positive")
prefix, rem = egypt_harmonic(r)
if rem == 0:
return prefix
x, y = rem.as_numer_denom()
if algorithm == "Greedy":
return prefix + egypt_greedy(x, y)
elif algorithm == "Graham Jewett":
return prefix + egypt_graham_jewett(x, y)
elif algorithm == "Takenouchi":
return prefix + egypt_takenouchi(x, y)
elif algorithm == "Golomb":
return prefix + egypt_golomb(x, y)
else:
raise ValueError("Entered invalid algorithm")
def egypt_greedy(x, y):
if x == 1:
return [y]
else:
a = (-y) % (x)
b = y*(y//x + 1)
c = gcd(a, b)
if c > 1:
num, denom = a//c, b//c
else:
num, denom = a, b
return [y//x + 1] + egypt_greedy(num, denom)
def egypt_graham_jewett(x, y):
l = [y] * x
# l is now a list of integers whose reciprocals sum to x/y.
# we shall now proceed to manipulate the elements of l without
# changing the reciprocated sum until all elements are unique.
while len(l) != len(set(l)):
l.sort() # so the list has duplicates. find a smallest pair
for i in range(len(l) - 1):
if l[i] == l[i + 1]:
break
# we have now identified a pair of identical
# elements: l[i] and l[i + 1].
# now comes the application of the result of graham and jewett:
l[i + 1] = l[i] + 1
# and we just iterate that until the list has no duplicates.
l.append(l[i]*(l[i] + 1))
return sorted(l)
def egypt_takenouchi(x, y):
l = [y] * x
while len(l) != len(set(l)):
l.sort()
for i in range(len(l) - 1):
if l[i] == l[i + 1]:
break
k = l[i]
if k % 2 == 0:
l[i] = l[i] // 2
del l[i + 1]
else:
l[i], l[i + 1] = (k + 1)//2, k*(k + 1)//2
return sorted(l)
def egypt_golomb(x, y):
if x == 1:
return [y]
xp = sympy.polys.ZZ.invert(int(x), int(y))
rv = [Integer(xp*y)]
rv.extend(egypt_golomb((x*xp - 1)//y, xp))
return sorted(rv)
def egypt_harmonic(r):
rv = []
d = Integer(1)
acc = Integer(0)
while acc + 1/d <= r:
acc += 1/d
rv.append(d)
d += 1
return (rv, r - acc)
|
f5f42155600f774cafcb8ca2b43bde2f271047f24aad8fdeb76c2f24b267908c
|
"""
Integer factorization
"""
from __future__ import print_function, division
import random
import math
from sympy.core import sympify
from sympy.core.compatibility import as_int, SYMPY_INTS, range
from sympy.core.evalf import bitcount
from sympy.core.expr import Expr
from sympy.core.function import Function
from sympy.core.logic import fuzzy_and
from sympy.core.mul import Mul
from sympy.core.numbers import igcd, ilcm, Rational
from sympy.core.power import integer_nthroot, Pow
from sympy.core.singleton import S
from .primetest import isprime
from .generate import sieve, primerange, nextprime
small_trailing = [0] * 256
for j in range(1,8):
small_trailing[1<<j::1<<(j+1)] = [j] * (1<<(7-j))
def smoothness(n):
"""
Return the B-smooth and B-power smooth values of n.
The smoothness of n is the largest prime factor of n; the power-
smoothness is the largest divisor raised to its multiplicity.
Examples
========
>>> from sympy.ntheory.factor_ import smoothness
>>> smoothness(2**7*3**2)
(3, 128)
>>> smoothness(2**4*13)
(13, 16)
>>> smoothness(2)
(2, 2)
See Also
========
factorint, smoothness_p
"""
if n == 1:
return (1, 1) # not prime, but otherwise this causes headaches
facs = factorint(n)
return max(facs), max(m**facs[m] for m in facs)
def smoothness_p(n, m=-1, power=0, visual=None):
"""
Return a list of [m, (p, (M, sm(p + m), psm(p + m)))...]
where:
1. p**M is the base-p divisor of n
2. sm(p + m) is the smoothness of p + m (m = -1 by default)
3. psm(p + m) is the power smoothness of p + m
The list is sorted according to smoothness (default) or by power smoothness
if power=1.
The smoothness of the numbers to the left (m = -1) or right (m = 1) of a
factor govern the results that are obtained from the p +/- 1 type factoring
methods.
>>> from sympy.ntheory.factor_ import smoothness_p, factorint
>>> smoothness_p(10431, m=1)
(1, [(3, (2, 2, 4)), (19, (1, 5, 5)), (61, (1, 31, 31))])
>>> smoothness_p(10431)
(-1, [(3, (2, 2, 2)), (19, (1, 3, 9)), (61, (1, 5, 5))])
>>> smoothness_p(10431, power=1)
(-1, [(3, (2, 2, 2)), (61, (1, 5, 5)), (19, (1, 3, 9))])
If visual=True then an annotated string will be returned:
>>> print(smoothness_p(21477639576571, visual=1))
p**i=4410317**1 has p-1 B=1787, B-pow=1787
p**i=4869863**1 has p-1 B=2434931, B-pow=2434931
This string can also be generated directly from a factorization dictionary
and vice versa:
>>> factorint(17*9)
{3: 2, 17: 1}
>>> smoothness_p(_)
'p**i=3**2 has p-1 B=2, B-pow=2\\np**i=17**1 has p-1 B=2, B-pow=16'
>>> smoothness_p(_)
{3: 2, 17: 1}
The table of the output logic is:
====== ====== ======= =======
| Visual
------ ----------------------
Input True False other
====== ====== ======= =======
dict str tuple str
str str tuple dict
tuple str tuple str
n str tuple tuple
mul str tuple tuple
====== ====== ======= =======
See Also
========
factorint, smoothness
"""
from sympy.utilities import flatten
# visual must be True, False or other (stored as None)
if visual in (1, 0):
visual = bool(visual)
elif visual not in (True, False):
visual = None
if type(n) is str:
if visual:
return n
d = {}
for li in n.splitlines():
k, v = [int(i) for i in
li.split('has')[0].split('=')[1].split('**')]
d[k] = v
if visual is not True and visual is not False:
return d
return smoothness_p(d, visual=False)
elif type(n) is not tuple:
facs = factorint(n, visual=False)
if power:
k = -1
else:
k = 1
if type(n) is not tuple:
rv = (m, sorted([(f,
tuple([M] + list(smoothness(f + m))))
for f, M in [i for i in facs.items()]],
key=lambda x: (x[1][k], x[0])))
else:
rv = n
if visual is False or (visual is not True) and (type(n) in [int, Mul]):
return rv
lines = []
for dat in rv[1]:
dat = flatten(dat)
dat.insert(2, m)
lines.append('p**i=%i**%i has p%+i B=%i, B-pow=%i' % tuple(dat))
return '\n'.join(lines)
def trailing(n):
"""Count the number of trailing zero digits in the binary
representation of n, i.e. determine the largest power of 2
that divides n.
Examples
========
>>> from sympy import trailing
>>> trailing(128)
7
>>> trailing(63)
0
"""
n = abs(int(n))
if not n:
return 0
low_byte = n & 0xff
if low_byte:
return small_trailing[low_byte]
# 2**m is quick for z up through 2**30
z = bitcount(n) - 1
if isinstance(z, SYMPY_INTS):
if n == 1 << z:
return z
if z < 300:
# fixed 8-byte reduction
t = 8
n >>= 8
while not n & 0xff:
n >>= 8
t += 8
return t + small_trailing[n & 0xff]
# binary reduction important when there might be a large
# number of trailing 0s
t = 0
p = 8
while not n & 1:
while not n & ((1 << p) - 1):
n >>= p
t += p
p *= 2
p //= 2
return t
def multiplicity(p, n):
"""
Find the greatest integer m such that p**m divides n.
Examples
========
>>> from sympy.ntheory import multiplicity
>>> from sympy.core.numbers import Rational as R
>>> [multiplicity(5, n) for n in [8, 5, 25, 125, 250]]
[0, 1, 2, 3, 3]
>>> multiplicity(3, R(1, 9))
-2
"""
try:
p, n = as_int(p), as_int(n)
except ValueError:
if all(isinstance(i, (SYMPY_INTS, Rational)) for i in (p, n)):
try:
p = Rational(p)
n = Rational(n)
if p.q == 1:
if n.p == 1:
return -multiplicity(p.p, n.q)
return multiplicity(p.p, n.p) - multiplicity(p.p, n.q)
elif p.p == 1:
return multiplicity(p.q, n.q)
else:
like = min(
multiplicity(p.p, n.p),
multiplicity(p.q, n.q))
cross = min(
multiplicity(p.q, n.p),
multiplicity(p.p, n.q))
return like - cross
except AttributeError:
pass
raise ValueError('expecting ints or fractions, got %s and %s' % (p, n))
if n == 0:
raise ValueError('no such integer exists: multiplicity of %s is not-defined' %(n))
if p == 2:
return trailing(n)
if p < 2:
raise ValueError('p must be an integer, 2 or larger, but got %s' % p)
if p == n:
return 1
m = 0
n, rem = divmod(n, p)
while not rem:
m += 1
if m > 5:
# The multiplicity could be very large. Better
# to increment in powers of two
e = 2
while 1:
ppow = p**e
if ppow < n:
nnew, rem = divmod(n, ppow)
if not rem:
m += e
e *= 2
n = nnew
continue
return m + multiplicity(p, n)
n, rem = divmod(n, p)
return m
def perfect_power(n, candidates=None, big=True, factor=True):
"""
Return ``(b, e)`` such that ``n`` == ``b**e`` if ``n`` is a
perfect power; otherwise return ``False``.
By default, the base is recursively decomposed and the exponents
collected so the largest possible ``e`` is sought. If ``big=False``
then the smallest possible ``e`` (thus prime) will be chosen.
If ``candidates`` for exponents are given, they are assumed to be sorted
and the first one that is larger than the computed maximum will signal
failure for the routine.
If ``factor=True`` then simultaneous factorization of n is attempted
since finding a factor indicates the only possible root for n. This
is True by default since only a few small factors will be tested in
the course of searching for the perfect power.
Examples
========
>>> from sympy import perfect_power
>>> perfect_power(16)
(2, 4)
>>> perfect_power(16, big = False)
(4, 2)
"""
n = int(n)
if n < 3:
return False
logn = math.log(n, 2)
max_possible = int(logn) + 2 # only check values less than this
not_square = n % 10 in [2, 3, 7, 8] # squares cannot end in 2, 3, 7, 8
if not candidates:
candidates = primerange(2 + not_square, max_possible)
afactor = 2 + n % 2
for e in candidates:
if e < 3:
if e == 1 or e == 2 and not_square:
continue
if e > max_possible:
return False
# see if there is a factor present
if factor:
if n % afactor == 0:
# find what the potential power is
if afactor == 2:
e = trailing(n)
else:
e = multiplicity(afactor, n)
# if it's a trivial power we are done
if e == 1:
return False
# maybe the bth root of n is exact
r, exact = integer_nthroot(n, e)
if not exact:
# then remove this factor and check to see if
# any of e's factors are a common exponent; if
# not then it's not a perfect power
n //= afactor**e
m = perfect_power(n, candidates=primefactors(e), big=big)
if m is False:
return False
else:
r, m = m
# adjust the two exponents so the bases can
# be combined
g = igcd(m, e)
if g == 1:
return False
m //= g
e //= g
r, e = r**m*afactor**e, g
if not big:
e0 = primefactors(e)
if len(e0) > 1 or e0[0] != e:
e0 = e0[0]
r, e = r**(e//e0), e0
return r, e
else:
# get the next factor ready for the next pass through the loop
afactor = nextprime(afactor)
# Weed out downright impossible candidates
if logn/e < 40:
b = 2.0**(logn/e)
if abs(int(b + 0.5) - b) > 0.01:
continue
# now see if the plausible e makes a perfect power
r, exact = integer_nthroot(n, e)
if exact:
if big:
m = perfect_power(r, big=big, factor=factor)
if m is not False:
r, e = m[0], e*m[1]
return int(r), e
else:
return False
def pollard_rho(n, s=2, a=1, retries=5, seed=1234, max_steps=None, F=None):
r"""
Use Pollard's rho method to try to extract a nontrivial factor
of ``n``. The returned factor may be a composite number. If no
factor is found, ``None`` is returned.
The algorithm generates pseudo-random values of x with a generator
function, replacing x with F(x). If F is not supplied then the
function x**2 + ``a`` is used. The first value supplied to F(x) is ``s``.
Upon failure (if ``retries`` is > 0) a new ``a`` and ``s`` will be
supplied; the ``a`` will be ignored if F was supplied.
The sequence of numbers generated by such functions generally have a
a lead-up to some number and then loop around back to that number and
begin to repeat the sequence, e.g. 1, 2, 3, 4, 5, 3, 4, 5 -- this leader
and loop look a bit like the Greek letter rho, and thus the name, 'rho'.
For a given function, very different leader-loop values can be obtained
so it is a good idea to allow for retries:
>>> from sympy.ntheory.generate import cycle_length
>>> n = 16843009
>>> F = lambda x:(2048*pow(x, 2, n) + 32767) % n
>>> for s in range(5):
... print('loop length = %4i; leader length = %3i' % next(cycle_length(F, s)))
...
loop length = 2489; leader length = 42
loop length = 78; leader length = 120
loop length = 1482; leader length = 99
loop length = 1482; leader length = 285
loop length = 1482; leader length = 100
Here is an explicit example where there is a two element leadup to
a sequence of 3 numbers (11, 14, 4) that then repeat:
>>> x=2
>>> for i in range(9):
... x=(x**2+12)%17
... print(x)
...
16
13
11
14
4
11
14
4
11
>>> next(cycle_length(lambda x: (x**2+12)%17, 2))
(3, 2)
>>> list(cycle_length(lambda x: (x**2+12)%17, 2, values=True))
[16, 13, 11, 14, 4]
Instead of checking the differences of all generated values for a gcd
with n, only the kth and 2*kth numbers are checked, e.g. 1st and 2nd,
2nd and 4th, 3rd and 6th until it has been detected that the loop has been
traversed. Loops may be many thousands of steps long before rho finds a
factor or reports failure. If ``max_steps`` is specified, the iteration
is cancelled with a failure after the specified number of steps.
Examples
========
>>> from sympy import pollard_rho
>>> n=16843009
>>> F=lambda x:(2048*pow(x,2,n) + 32767) % n
>>> pollard_rho(n, F=F)
257
Use the default setting with a bad value of ``a`` and no retries:
>>> pollard_rho(n, a=n-2, retries=0)
If retries is > 0 then perhaps the problem will correct itself when
new values are generated for a:
>>> pollard_rho(n, a=n-2, retries=1)
257
References
==========
.. [1] Richard Crandall & Carl Pomerance (2005), "Prime Numbers:
A Computational Perspective", Springer, 2nd edition, 229-231
"""
n = int(n)
if n < 5:
raise ValueError('pollard_rho should receive n > 4')
prng = random.Random(seed + retries)
V = s
for i in range(retries + 1):
U = V
if not F:
F = lambda x: (pow(x, 2, n) + a) % n
j = 0
while 1:
if max_steps and (j > max_steps):
break
j += 1
U = F(U)
V = F(F(V)) # V is 2x further along than U
g = igcd(U - V, n)
if g == 1:
continue
if g == n:
break
return int(g)
V = prng.randint(0, n - 1)
a = prng.randint(1, n - 3) # for x**2 + a, a%n should not be 0 or -2
F = None
return None
def pollard_pm1(n, B=10, a=2, retries=0, seed=1234):
"""
Use Pollard's p-1 method to try to extract a nontrivial factor
of ``n``. Either a divisor (perhaps composite) or ``None`` is returned.
The value of ``a`` is the base that is used in the test gcd(a**M - 1, n).
The default is 2. If ``retries`` > 0 then if no factor is found after the
first attempt, a new ``a`` will be generated randomly (using the ``seed``)
and the process repeated.
Note: the value of M is lcm(1..B) = reduce(ilcm, range(2, B + 1)).
A search is made for factors next to even numbers having a power smoothness
less than ``B``. Choosing a larger B increases the likelihood of finding a
larger factor but takes longer. Whether a factor of n is found or not
depends on ``a`` and the power smoothness of the even number just less than
the factor p (hence the name p - 1).
Although some discussion of what constitutes a good ``a`` some
descriptions are hard to interpret. At the modular.math site referenced
below it is stated that if gcd(a**M - 1, n) = N then a**M % q**r is 1
for every prime power divisor of N. But consider the following:
>>> from sympy.ntheory.factor_ import smoothness_p, pollard_pm1
>>> n=257*1009
>>> smoothness_p(n)
(-1, [(257, (1, 2, 256)), (1009, (1, 7, 16))])
So we should (and can) find a root with B=16:
>>> pollard_pm1(n, B=16, a=3)
1009
If we attempt to increase B to 256 we find that it doesn't work:
>>> pollard_pm1(n, B=256)
>>>
But if the value of ``a`` is changed we find that only multiples of
257 work, e.g.:
>>> pollard_pm1(n, B=256, a=257)
1009
Checking different ``a`` values shows that all the ones that didn't
work had a gcd value not equal to ``n`` but equal to one of the
factors:
>>> from sympy.core.numbers import ilcm, igcd
>>> from sympy import factorint, Pow
>>> M = 1
>>> for i in range(2, 256):
... M = ilcm(M, i)
...
>>> set([igcd(pow(a, M, n) - 1, n) for a in range(2, 256) if
... igcd(pow(a, M, n) - 1, n) != n])
{1009}
But does aM % d for every divisor of n give 1?
>>> aM = pow(255, M, n)
>>> [(d, aM%Pow(*d.args)) for d in factorint(n, visual=True).args]
[(257**1, 1), (1009**1, 1)]
No, only one of them. So perhaps the principle is that a root will
be found for a given value of B provided that:
1) the power smoothness of the p - 1 value next to the root
does not exceed B
2) a**M % p != 1 for any of the divisors of n.
By trying more than one ``a`` it is possible that one of them
will yield a factor.
Examples
========
With the default smoothness bound, this number can't be cracked:
>>> from sympy.ntheory import pollard_pm1, primefactors
>>> pollard_pm1(21477639576571)
Increasing the smoothness bound helps:
>>> pollard_pm1(21477639576571, B=2000)
4410317
Looking at the smoothness of the factors of this number we find:
>>> from sympy.utilities import flatten
>>> from sympy.ntheory.factor_ import smoothness_p, factorint
>>> print(smoothness_p(21477639576571, visual=1))
p**i=4410317**1 has p-1 B=1787, B-pow=1787
p**i=4869863**1 has p-1 B=2434931, B-pow=2434931
The B and B-pow are the same for the p - 1 factorizations of the divisors
because those factorizations had a very large prime factor:
>>> factorint(4410317 - 1)
{2: 2, 617: 1, 1787: 1}
>>> factorint(4869863-1)
{2: 1, 2434931: 1}
Note that until B reaches the B-pow value of 1787, the number is not cracked;
>>> pollard_pm1(21477639576571, B=1786)
>>> pollard_pm1(21477639576571, B=1787)
4410317
The B value has to do with the factors of the number next to the divisor,
not the divisors themselves. A worst case scenario is that the number next
to the factor p has a large prime divisisor or is a perfect power. If these
conditions apply then the power-smoothness will be about p/2 or p. The more
realistic is that there will be a large prime factor next to p requiring
a B value on the order of p/2. Although primes may have been searched for
up to this level, the p/2 is a factor of p - 1, something that we don't
know. The modular.math reference below states that 15% of numbers in the
range of 10**15 to 15**15 + 10**4 are 10**6 power smooth so a B of 10**6
will fail 85% of the time in that range. From 10**8 to 10**8 + 10**3 the
percentages are nearly reversed...but in that range the simple trial
division is quite fast.
References
==========
.. [1] Richard Crandall & Carl Pomerance (2005), "Prime Numbers:
A Computational Perspective", Springer, 2nd edition, 236-238
.. [2] http://modular.math.washington.edu/edu/2007/spring/ent/ent-html/node81.html
.. [3] https://www.cs.toronto.edu/~yuvalf/Factorization.pdf
"""
n = int(n)
if n < 4 or B < 3:
raise ValueError('pollard_pm1 should receive n > 3 and B > 2')
prng = random.Random(seed + B)
# computing a**lcm(1,2,3,..B) % n for B > 2
# it looks weird, but it's right: primes run [2, B]
# and the answer's not right until the loop is done.
for i in range(retries + 1):
aM = a
for p in sieve.primerange(2, B + 1):
e = int(math.log(B, p))
aM = pow(aM, pow(p, e), n)
g = igcd(aM - 1, n)
if 1 < g < n:
return int(g)
# get a new a:
# since the exponent, lcm(1..B), is even, if we allow 'a' to be 'n-1'
# then (n - 1)**even % n will be 1 which will give a g of 0 and 1 will
# give a zero, too, so we set the range as [2, n-2]. Some references
# say 'a' should be coprime to n, but either will detect factors.
a = prng.randint(2, n - 2)
def _trial(factors, n, candidates, verbose=False):
"""
Helper function for integer factorization. Trial factors ``n`
against all integers given in the sequence ``candidates``
and updates the dict ``factors`` in-place. Returns the reduced
value of ``n`` and a flag indicating whether any factors were found.
"""
if verbose:
factors0 = list(factors.keys())
nfactors = len(factors)
for d in candidates:
if n % d == 0:
m = multiplicity(d, n)
n //= d**m
factors[d] = m
if verbose:
for k in sorted(set(factors).difference(set(factors0))):
print(factor_msg % (k, factors[k]))
return int(n), len(factors) != nfactors
def _check_termination(factors, n, limitp1, use_trial, use_rho, use_pm1,
verbose):
"""
Helper function for integer factorization. Checks if ``n``
is a prime or a perfect power, and in those cases updates
the factorization and raises ``StopIteration``.
"""
if verbose:
print('Check for termination')
# since we've already been factoring there is no need to do
# simultaneous factoring with the power check
p = perfect_power(n, factor=False)
if p is not False:
base, exp = p
if limitp1:
limit = limitp1 - 1
else:
limit = limitp1
facs = factorint(base, limit, use_trial, use_rho, use_pm1,
verbose=False)
for b, e in facs.items():
if verbose:
print(factor_msg % (b, e))
factors[b] = exp*e
raise StopIteration
if isprime(n):
factors[int(n)] = 1
raise StopIteration
if n == 1:
raise StopIteration
trial_int_msg = "Trial division with ints [%i ... %i] and fail_max=%i"
trial_msg = "Trial division with primes [%i ... %i]"
rho_msg = "Pollard's rho with retries %i, max_steps %i and seed %i"
pm1_msg = "Pollard's p-1 with smoothness bound %i and seed %i"
factor_msg = '\t%i ** %i'
fermat_msg = 'Close factors satisying Fermat condition found.'
complete_msg = 'Factorization is complete.'
def _factorint_small(factors, n, limit, fail_max):
"""
Return the value of n and either a 0 (indicating that factorization up
to the limit was complete) or else the next near-prime that would have
been tested.
Factoring stops if there are fail_max unsuccessful tests in a row.
If factors of n were found they will be in the factors dictionary as
{factor: multiplicity} and the returned value of n will have had those
factors removed. The factors dictionary is modified in-place.
"""
def done(n, d):
"""return n, d if the sqrt(n) wasn't reached yet, else
n, 0 indicating that factoring is done.
"""
if d*d <= n:
return n, d
return n, 0
d = 2
m = trailing(n)
if m:
factors[d] = m
n >>= m
d = 3
if limit < d:
if n > 1:
factors[n] = 1
return done(n, d)
# reduce
m = 0
while n % d == 0:
n //= d
m += 1
if m == 20:
mm = multiplicity(d, n)
m += mm
n //= d**mm
break
if m:
factors[d] = m
# when d*d exceeds maxx or n we are done; if limit**2 is greater
# than n then maxx is set to zero so the value of n will flag the finish
if limit*limit > n:
maxx = 0
else:
maxx = limit*limit
dd = maxx or n
d = 5
fails = 0
while fails < fail_max:
if d*d > dd:
break
# d = 6*i - 1
# reduce
m = 0
while n % d == 0:
n //= d
m += 1
if m == 20:
mm = multiplicity(d, n)
m += mm
n //= d**mm
break
if m:
factors[d] = m
dd = maxx or n
fails = 0
else:
fails += 1
d += 2
if d*d > dd:
break
# d = 6*i - 1
# reduce
m = 0
while n % d == 0:
n //= d
m += 1
if m == 20:
mm = multiplicity(d, n)
m += mm
n //= d**mm
break
if m:
factors[d] = m
dd = maxx or n
fails = 0
else:
fails += 1
# d = 6*(i + 1) - 1
d += 4
return done(n, d)
def factorint(n, limit=None, use_trial=True, use_rho=True, use_pm1=True,
verbose=False, visual=None, multiple=False):
r"""
Given a positive integer ``n``, ``factorint(n)`` returns a dict containing
the prime factors of ``n`` as keys and their respective multiplicities
as values. For example:
>>> from sympy.ntheory import factorint
>>> factorint(2000) # 2000 = (2**4) * (5**3)
{2: 4, 5: 3}
>>> factorint(65537) # This number is prime
{65537: 1}
For input less than 2, factorint behaves as follows:
- ``factorint(1)`` returns the empty factorization, ``{}``
- ``factorint(0)`` returns ``{0:1}``
- ``factorint(-n)`` adds ``-1:1`` to the factors and then factors ``n``
Partial Factorization:
If ``limit`` (> 3) is specified, the search is stopped after performing
trial division up to (and including) the limit (or taking a
corresponding number of rho/p-1 steps). This is useful if one has
a large number and only is interested in finding small factors (if
any). Note that setting a limit does not prevent larger factors
from being found early; it simply means that the largest factor may
be composite. Since checking for perfect power is relatively cheap, it is
done regardless of the limit setting.
This number, for example, has two small factors and a huge
semi-prime factor that cannot be reduced easily:
>>> from sympy.ntheory import isprime
>>> from sympy.core.compatibility import long
>>> a = 1407633717262338957430697921446883
>>> f = factorint(a, limit=10000)
>>> f == {991: 1, long(202916782076162456022877024859): 1, 7: 1}
True
>>> isprime(max(f))
False
This number has a small factor and a residual perfect power whose
base is greater than the limit:
>>> factorint(3*101**7, limit=5)
{3: 1, 101: 7}
List of Factors:
If ``multiple`` is set to ``True`` then a list containing the
prime factors including multiplicities is returned.
>>> factorint(24, multiple=True)
[2, 2, 2, 3]
Visual Factorization:
If ``visual`` is set to ``True``, then it will return a visual
factorization of the integer. For example:
>>> from sympy import pprint
>>> pprint(factorint(4200, visual=True))
3 1 2 1
2 *3 *5 *7
Note that this is achieved by using the evaluate=False flag in Mul
and Pow. If you do other manipulations with an expression where
evaluate=False, it may evaluate. Therefore, you should use the
visual option only for visualization, and use the normal dictionary
returned by visual=False if you want to perform operations on the
factors.
You can easily switch between the two forms by sending them back to
factorint:
>>> from sympy import Mul, Pow
>>> regular = factorint(1764); regular
{2: 2, 3: 2, 7: 2}
>>> pprint(factorint(regular))
2 2 2
2 *3 *7
>>> visual = factorint(1764, visual=True); pprint(visual)
2 2 2
2 *3 *7
>>> print(factorint(visual))
{2: 2, 3: 2, 7: 2}
If you want to send a number to be factored in a partially factored form
you can do so with a dictionary or unevaluated expression:
>>> factorint(factorint({4: 2, 12: 3})) # twice to toggle to dict form
{2: 10, 3: 3}
>>> factorint(Mul(4, 12, evaluate=False))
{2: 4, 3: 1}
The table of the output logic is:
====== ====== ======= =======
Visual
------ ----------------------
Input True False other
====== ====== ======= =======
dict mul dict mul
n mul dict dict
mul mul dict dict
====== ====== ======= =======
Notes
=====
Algorithm:
The function switches between multiple algorithms. Trial division
quickly finds small factors (of the order 1-5 digits), and finds
all large factors if given enough time. The Pollard rho and p-1
algorithms are used to find large factors ahead of time; they
will often find factors of the order of 10 digits within a few
seconds:
>>> factors = factorint(12345678910111213141516)
>>> for base, exp in sorted(factors.items()):
... print('%s %s' % (base, exp))
...
2 2
2507191691 1
1231026625769 1
Any of these methods can optionally be disabled with the following
boolean parameters:
- ``use_trial``: Toggle use of trial division
- ``use_rho``: Toggle use of Pollard's rho method
- ``use_pm1``: Toggle use of Pollard's p-1 method
``factorint`` also periodically checks if the remaining part is
a prime number or a perfect power, and in those cases stops.
For unevaluated factorial, it uses Legendre's formula(theorem).
If ``verbose`` is set to ``True``, detailed progress is printed.
See Also
========
smoothness, smoothness_p, divisors
"""
if multiple:
fac = factorint(n, limit=limit, use_trial=use_trial,
use_rho=use_rho, use_pm1=use_pm1,
verbose=verbose, visual=False, multiple=False)
factorlist = sum(([p] * fac[p] if fac[p] > 0 else [S(1)/p]*(-fac[p])
for p in sorted(fac)), [])
return factorlist
factordict = {}
if visual and not isinstance(n, Mul) and not isinstance(n, dict):
factordict = factorint(n, limit=limit, use_trial=use_trial,
use_rho=use_rho, use_pm1=use_pm1,
verbose=verbose, visual=False)
elif isinstance(n, Mul):
factordict = dict([(int(k), int(v)) for k, v in
list(n.as_powers_dict().items())])
elif isinstance(n, dict):
factordict = n
if factordict and (isinstance(n, Mul) or isinstance(n, dict)):
# check it
for k in list(factordict.keys()):
if isprime(k):
continue
e = factordict.pop(k)
d = factorint(k, limit=limit, use_trial=use_trial, use_rho=use_rho,
use_pm1=use_pm1, verbose=verbose, visual=False)
for k, v in d.items():
if k in factordict:
factordict[k] += v*e
else:
factordict[k] = v*e
if visual or (type(n) is dict and
visual is not True and
visual is not False):
if factordict == {}:
return S.One
if -1 in factordict:
factordict.pop(-1)
args = [S.NegativeOne]
else:
args = []
args.extend([Pow(*i, evaluate=False)
for i in sorted(factordict.items())])
return Mul(*args, evaluate=False)
elif isinstance(n, dict) or isinstance(n, Mul):
return factordict
assert use_trial or use_rho or use_pm1
from sympy.functions.combinatorial.factorials import factorial
if isinstance(n, factorial):
x = as_int(n.args[0])
if x >= 20:
factors = {}
m = 2 # to initialize the if condition below
for p in sieve.primerange(2, x + 1):
if m > 1:
m, q = 0, x // p
while q != 0:
m += q
q //= p
factors[p] = m
if factors and verbose:
for k in sorted(factors):
print(factor_msg % (k, factors[k]))
if verbose:
print(complete_msg)
return factors
else:
# if n < 20!, direct computation is faster
# since it uses a lookup table
n = n.func(x)
n = as_int(n)
if limit:
limit = int(limit)
# special cases
if n < 0:
factors = factorint(
-n, limit=limit, use_trial=use_trial, use_rho=use_rho,
use_pm1=use_pm1, verbose=verbose, visual=False)
factors[-1] = 1
return factors
if limit and limit < 2:
if n == 1:
return {}
return {n: 1}
elif n < 10:
# doing this we are assured of getting a limit > 2
# when we have to compute it later
return [{0: 1}, {}, {2: 1}, {3: 1}, {2: 2}, {5: 1},
{2: 1, 3: 1}, {7: 1}, {2: 3}, {3: 2}][n]
factors = {}
# do simplistic factorization
if verbose:
sn = str(n)
if len(sn) > 50:
print('Factoring %s' % sn[:5] + \
'..(%i other digits)..' % (len(sn) - 10) + sn[-5:])
else:
print('Factoring', n)
if use_trial:
# this is the preliminary factorization for small factors
small = 2**15
fail_max = 600
small = min(small, limit or small)
if verbose:
print(trial_int_msg % (2, small, fail_max))
n, next_p = _factorint_small(factors, n, small, fail_max)
else:
next_p = 2
if factors and verbose:
for k in sorted(factors):
print(factor_msg % (k, factors[k]))
if next_p == 0:
if n > 1:
factors[int(n)] = 1
if verbose:
print(complete_msg)
return factors
# continue with more advanced factorization methods
# first check if the simplistic run didn't finish
# because of the limit and check for a perfect
# power before exiting
try:
if limit and next_p > limit:
if verbose:
print('Exceeded limit:', limit)
_check_termination(factors, n, limit, use_trial, use_rho, use_pm1,
verbose)
if n > 1:
factors[int(n)] = 1
return factors
else:
# Before quitting (or continuing on)...
# ...do a Fermat test since it's so easy and we need the
# square root anyway. Finding 2 factors is easy if they are
# "close enough." This is the big root equivalent of dividing by
# 2, 3, 5.
sqrt_n = integer_nthroot(n, 2)[0]
a = sqrt_n + 1
a2 = a**2
b2 = a2 - n
for i in range(3):
b, fermat = integer_nthroot(b2, 2)
if fermat:
break
b2 += 2*a + 1 # equiv to (a + 1)**2 - n
a += 1
if fermat:
if verbose:
print(fermat_msg)
if limit:
limit -= 1
for r in [a - b, a + b]:
facs = factorint(r, limit=limit, use_trial=use_trial,
use_rho=use_rho, use_pm1=use_pm1,
verbose=verbose)
factors.update(facs)
raise StopIteration
# ...see if factorization can be terminated
_check_termination(factors, n, limit, use_trial, use_rho, use_pm1,
verbose)
except StopIteration:
if verbose:
print(complete_msg)
return factors
# these are the limits for trial division which will
# be attempted in parallel with pollard methods
low, high = next_p, 2*next_p
limit = limit or sqrt_n
# add 1 to make sure limit is reached in primerange calls
limit += 1
while 1:
try:
high_ = high
if limit < high_:
high_ = limit
# Trial division
if use_trial:
if verbose:
print(trial_msg % (low, high_))
ps = sieve.primerange(low, high_)
n, found_trial = _trial(factors, n, ps, verbose)
if found_trial:
_check_termination(factors, n, limit, use_trial, use_rho,
use_pm1, verbose)
else:
found_trial = False
if high > limit:
if verbose:
print('Exceeded limit:', limit)
if n > 1:
factors[int(n)] = 1
raise StopIteration
# Only used advanced methods when no small factors were found
if not found_trial:
if (use_pm1 or use_rho):
high_root = max(int(math.log(high_**0.7)), low, 3)
# Pollard p-1
if use_pm1:
if verbose:
print(pm1_msg % (high_root, high_))
c = pollard_pm1(n, B=high_root, seed=high_)
if c:
# factor it and let _trial do the update
ps = factorint(c, limit=limit - 1,
use_trial=use_trial,
use_rho=use_rho,
use_pm1=use_pm1,
verbose=verbose)
n, _ = _trial(factors, n, ps, verbose=False)
_check_termination(factors, n, limit, use_trial,
use_rho, use_pm1, verbose)
# Pollard rho
if use_rho:
max_steps = high_root
if verbose:
print(rho_msg % (1, max_steps, high_))
c = pollard_rho(n, retries=1, max_steps=max_steps,
seed=high_)
if c:
# factor it and let _trial do the update
ps = factorint(c, limit=limit - 1,
use_trial=use_trial,
use_rho=use_rho,
use_pm1=use_pm1,
verbose=verbose)
n, _ = _trial(factors, n, ps, verbose=False)
_check_termination(factors, n, limit, use_trial,
use_rho, use_pm1, verbose)
except StopIteration:
if verbose:
print(complete_msg)
return factors
low, high = high, high*2
def factorrat(rat, limit=None, use_trial=True, use_rho=True, use_pm1=True,
verbose=False, visual=None, multiple=False):
r"""
Given a Rational ``r``, ``factorrat(r)`` returns a dict containing
the prime factors of ``r`` as keys and their respective multiplicities
as values. For example:
>>> from sympy.ntheory import factorrat
>>> from sympy.core.symbol import S
>>> factorrat(S(8)/9) # 8/9 = (2**3) * (3**-2)
{2: 3, 3: -2}
>>> factorrat(S(-1)/987) # -1/789 = -1 * (3**-1) * (7**-1) * (47**-1)
{-1: 1, 3: -1, 7: -1, 47: -1}
Please see the docstring for ``factorint`` for detailed explanations
and examples of the following keywords:
- ``limit``: Integer limit up to which trial division is done
- ``use_trial``: Toggle use of trial division
- ``use_rho``: Toggle use of Pollard's rho method
- ``use_pm1``: Toggle use of Pollard's p-1 method
- ``verbose``: Toggle detailed printing of progress
- ``multiple``: Toggle returning a list of factors or dict
- ``visual``: Toggle product form of output
"""
from collections import defaultdict
if multiple:
fac = factorrat(rat, limit=limit, use_trial=use_trial,
use_rho=use_rho, use_pm1=use_pm1,
verbose=verbose, visual=False, multiple=False)
factorlist = sum(([p] * fac[p] if fac[p] > 0 else [S(1)/p]*(-fac[p])
for p, _ in sorted(fac.items(),
key=lambda elem: elem[0]
if elem[1] > 0
else 1/elem[0])), [])
return factorlist
f = factorint(rat.p, limit=limit, use_trial=use_trial,
use_rho=use_rho, use_pm1=use_pm1,
verbose=verbose).copy()
f = defaultdict(int, f)
for p, e in factorint(rat.q, limit=limit,
use_trial=use_trial,
use_rho=use_rho,
use_pm1=use_pm1,
verbose=verbose).items():
f[p] += -e
if len(f) > 1 and 1 in f:
del f[1]
if not visual:
return dict(f)
else:
if -1 in f:
f.pop(-1)
args = [S.NegativeOne]
else:
args = []
args.extend([Pow(*i, evaluate=False)
for i in sorted(f.items())])
return Mul(*args, evaluate=False)
def primefactors(n, limit=None, verbose=False):
"""Return a sorted list of n's prime factors, ignoring multiplicity
and any composite factor that remains if the limit was set too low
for complete factorization. Unlike factorint(), primefactors() does
not return -1 or 0.
Examples
========
>>> from sympy.ntheory import primefactors, factorint, isprime
>>> primefactors(6)
[2, 3]
>>> primefactors(-5)
[5]
>>> sorted(factorint(123456).items())
[(2, 6), (3, 1), (643, 1)]
>>> primefactors(123456)
[2, 3, 643]
>>> sorted(factorint(10000000001, limit=200).items())
[(101, 1), (99009901, 1)]
>>> isprime(99009901)
False
>>> primefactors(10000000001, limit=300)
[101]
See Also
========
divisors
"""
n = int(n)
factors = sorted(factorint(n, limit=limit, verbose=verbose).keys())
s = [f for f in factors[:-1:] if f not in [-1, 0, 1]]
if factors and isprime(factors[-1]):
s += [factors[-1]]
return s
def _divisors(n):
"""Helper function for divisors which generates the divisors."""
factordict = factorint(n)
ps = sorted(factordict.keys())
def rec_gen(n=0):
if n == len(ps):
yield 1
else:
pows = [1]
for j in range(factordict[ps[n]]):
pows.append(pows[-1] * ps[n])
for q in rec_gen(n + 1):
for p in pows:
yield p * q
for p in rec_gen():
yield p
def divisors(n, generator=False):
r"""
Return all divisors of n sorted from 1..n by default.
If generator is ``True`` an unordered generator is returned.
The number of divisors of n can be quite large if there are many
prime factors (counting repeated factors). If only the number of
factors is desired use divisor_count(n).
Examples
========
>>> from sympy import divisors, divisor_count
>>> divisors(24)
[1, 2, 3, 4, 6, 8, 12, 24]
>>> divisor_count(24)
8
>>> list(divisors(120, generator=True))
[1, 2, 4, 8, 3, 6, 12, 24, 5, 10, 20, 40, 15, 30, 60, 120]
Notes
=====
This is a slightly modified version of Tim Peters referenced at:
https://stackoverflow.com/questions/1010381/python-factorization
See Also
========
primefactors, factorint, divisor_count
"""
n = as_int(abs(n))
if isprime(n):
return [1, n]
if n == 1:
return [1]
if n == 0:
return []
rv = _divisors(n)
if not generator:
return sorted(rv)
return rv
def divisor_count(n, modulus=1):
"""
Return the number of divisors of ``n``. If ``modulus`` is not 1 then only
those that are divisible by ``modulus`` are counted.
Examples
========
>>> from sympy import divisor_count
>>> divisor_count(6)
4
See Also
========
factorint, divisors, totient
"""
if not modulus:
return 0
elif modulus != 1:
n, r = divmod(n, modulus)
if r:
return 0
if n == 0:
return 0
return Mul(*[v + 1 for k, v in factorint(n).items() if k > 1])
def _udivisors(n):
"""Helper function for udivisors which generates the unitary divisors."""
factorpows = [p**e for p, e in factorint(n).items()]
for i in range(2**len(factorpows)):
d, j, k = 1, i, 0
while j:
if (j & 1):
d *= factorpows[k]
j >>= 1
k += 1
yield d
def udivisors(n, generator=False):
r"""
Return all unitary divisors of n sorted from 1..n by default.
If generator is ``True`` an unordered generator is returned.
The number of unitary divisors of n can be quite large if there are many
prime factors. If only the number of unitary divisors is desired use
udivisor_count(n).
Examples
========
>>> from sympy.ntheory.factor_ import udivisors, udivisor_count
>>> udivisors(15)
[1, 3, 5, 15]
>>> udivisor_count(15)
4
>>> sorted(udivisors(120, generator=True))
[1, 3, 5, 8, 15, 24, 40, 120]
See Also
========
primefactors, factorint, divisors, divisor_count, udivisor_count
References
==========
.. [1] https://en.wikipedia.org/wiki/Unitary_divisor
.. [2] http://mathworld.wolfram.com/UnitaryDivisor.html
"""
n = as_int(abs(n))
if isprime(n):
return [1, n]
if n == 1:
return [1]
if n == 0:
return []
rv = _udivisors(n)
if not generator:
return sorted(rv)
return rv
def udivisor_count(n):
"""
Return the number of unitary divisors of ``n``.
Parameters
==========
n : integer
Examples
========
>>> from sympy.ntheory.factor_ import udivisor_count
>>> udivisor_count(120)
8
See Also
========
factorint, divisors, udivisors, divisor_count, totient
References
==========
.. [1] http://mathworld.wolfram.com/UnitaryDivisorFunction.html
"""
if n == 0:
return 0
return 2**len([p for p in factorint(n) if p > 1])
def _antidivisors(n):
"""Helper function for antidivisors which generates the antidivisors."""
for d in _divisors(n):
y = 2*d
if n > y and n % y:
yield y
for d in _divisors(2*n-1):
if n > d >= 2 and n % d:
yield d
for d in _divisors(2*n+1):
if n > d >= 2 and n % d:
yield d
def antidivisors(n, generator=False):
r"""
Return all antidivisors of n sorted from 1..n by default.
Antidivisors [1]_ of n are numbers that do not divide n by the largest
possible margin. If generator is True an unordered generator is returned.
Examples
========
>>> from sympy.ntheory.factor_ import antidivisors
>>> antidivisors(24)
[7, 16]
>>> sorted(antidivisors(128, generator=True))
[3, 5, 15, 17, 51, 85]
See Also
========
primefactors, factorint, divisors, divisor_count, antidivisor_count
References
==========
.. [1] definition is described in https://oeis.org/A066272/a066272a.html
"""
n = as_int(abs(n))
if n <= 2:
return []
rv = _antidivisors(n)
if not generator:
return sorted(rv)
return rv
def antidivisor_count(n):
"""
Return the number of antidivisors [1]_ of ``n``.
Parameters
==========
n : integer
Examples
========
>>> from sympy.ntheory.factor_ import antidivisor_count
>>> antidivisor_count(13)
4
>>> antidivisor_count(27)
5
See Also
========
factorint, divisors, antidivisors, divisor_count, totient
References
==========
.. [1] formula from https://oeis.org/A066272
"""
n = as_int(abs(n))
if n <= 2:
return 0
return divisor_count(2*n - 1) + divisor_count(2*n + 1) + \
divisor_count(n) - divisor_count(n, 2) - 5
class totient(Function):
r"""
Calculate the Euler totient function phi(n)
``totient(n)`` or `\phi(n)` is the number of positive integers `\leq` n
that are relatively prime to n.
Parameters
==========
n : integer
Examples
========
>>> from sympy.ntheory import totient
>>> totient(1)
1
>>> totient(25)
20
See Also
========
divisor_count
References
==========
.. [1] https://en.wikipedia.org/wiki/Euler%27s_totient_function
.. [2] http://mathworld.wolfram.com/TotientFunction.html
"""
@classmethod
def eval(cls, n):
n = sympify(n)
if n.is_Integer:
if n < 1:
raise ValueError("n must be a positive integer")
factors = factorint(n)
t = 1
for p, k in factors.items():
t *= (p - 1) * p**(k - 1)
return t
elif not isinstance(n, Expr) or (n.is_integer is False) or (n.is_positive is False):
raise ValueError("n must be a positive integer")
def _eval_is_integer(self):
return fuzzy_and([self.args[0].is_integer, self.args[0].is_positive])
class reduced_totient(Function):
r"""
Calculate the Carmichael reduced totient function lambda(n)
``reduced_totient(n)`` or `\lambda(n)` is the smallest m > 0 such that
`k^m \equiv 1 \mod n` for all k relatively prime to n.
Examples
========
>>> from sympy.ntheory import reduced_totient
>>> reduced_totient(1)
1
>>> reduced_totient(8)
2
>>> reduced_totient(30)
4
See Also
========
totient
References
==========
.. [1] https://en.wikipedia.org/wiki/Carmichael_function
.. [2] http://mathworld.wolfram.com/CarmichaelFunction.html
"""
@classmethod
def eval(cls, n):
n = sympify(n)
if n.is_Integer:
if n < 1:
raise ValueError("n must be a positive integer")
factors = factorint(n)
t = 1
for p, k in factors.items():
if p == 2 and k > 2:
t = ilcm(t, 2**(k - 2))
else:
t = ilcm(t, (p - 1) * p**(k - 1))
return t
def _eval_is_integer(self):
return fuzzy_and([self.args[0].is_integer, self.args[0].is_positive])
class divisor_sigma(Function):
r"""
Calculate the divisor function `\sigma_k(n)` for positive integer n
``divisor_sigma(n, k)`` is equal to ``sum([x**k for x in divisors(n)])``
If n's prime factorization is:
.. math ::
n = \prod_{i=1}^\omega p_i^{m_i},
then
.. math ::
\sigma_k(n) = \prod_{i=1}^\omega (1+p_i^k+p_i^{2k}+\cdots
+ p_i^{m_ik}).
Parameters
==========
n : integer
k : integer, optional
power of divisors in the sum
for k = 0, 1:
``divisor_sigma(n, 0)`` is equal to ``divisor_count(n)``
``divisor_sigma(n, 1)`` is equal to ``sum(divisors(n))``
Default for k is 1.
Examples
========
>>> from sympy.ntheory import divisor_sigma
>>> divisor_sigma(18, 0)
6
>>> divisor_sigma(39, 1)
56
>>> divisor_sigma(12, 2)
210
>>> divisor_sigma(37)
38
See Also
========
divisor_count, totient, divisors, factorint
References
==========
.. [1] https://en.wikipedia.org/wiki/Divisor_function
"""
@classmethod
def eval(cls, n, k=1):
n = sympify(n)
k = sympify(k)
if n.is_prime:
return 1 + n**k
if n.is_Integer:
if n <= 0:
raise ValueError("n must be a positive integer")
else:
return Mul(*[(p**(k*(e + 1)) - 1)/(p**k - 1) if k != 0
else e + 1 for p, e in factorint(n).items()])
def core(n, t=2):
r"""
Calculate core(n, t) = `core_t(n)` of a positive integer n
``core_2(n)`` is equal to the squarefree part of n
If n's prime factorization is:
.. math ::
n = \prod_{i=1}^\omega p_i^{m_i},
then
.. math ::
core_t(n) = \prod_{i=1}^\omega p_i^{m_i \mod t}.
Parameters
==========
n : integer
t : integer
core(n, t) calculates the t-th power free part of n
``core(n, 2)`` is the squarefree part of ``n``
``core(n, 3)`` is the cubefree part of ``n``
Default for t is 2.
Examples
========
>>> from sympy.ntheory.factor_ import core
>>> core(24, 2)
6
>>> core(9424, 3)
1178
>>> core(379238)
379238
>>> core(15**11, 10)
15
See Also
========
factorint, sympy.solvers.diophantine.square_factor
References
==========
.. [1] https://en.wikipedia.org/wiki/Square-free_integer#Squarefree_core
"""
n = as_int(n)
t = as_int(t)
if n <= 0:
raise ValueError("n must be a positive integer")
elif t <= 1:
raise ValueError("t must be >= 2")
else:
y = 1
for p, e in factorint(n).items():
y *= p**(e % t)
return y
def digits(n, b=10):
"""
Return a list of the digits of n in base b. The first element in the list
is b (or -b if n is negative).
Examples
========
>>> from sympy.ntheory.factor_ import digits
>>> digits(35)
[10, 3, 5]
>>> digits(27, 2)
[2, 1, 1, 0, 1, 1]
>>> digits(65536, 256)
[256, 1, 0, 0]
>>> digits(-3958, 27)
[-27, 5, 11, 16]
"""
b = as_int(b)
n = as_int(n)
if b <= 1:
raise ValueError("b must be >= 2")
else:
x, y = abs(n), []
while x >= b:
x, r = divmod(x, b)
y.append(r)
y.append(x)
y.append(-b if n < 0 else b)
y.reverse()
return y
class udivisor_sigma(Function):
r"""
Calculate the unitary divisor function `\sigma_k^*(n)` for positive integer n
``udivisor_sigma(n, k)`` is equal to ``sum([x**k for x in udivisors(n)])``
If n's prime factorization is:
.. math ::
n = \prod_{i=1}^\omega p_i^{m_i},
then
.. math ::
\sigma_k^*(n) = \prod_{i=1}^\omega (1+ p_i^{m_ik}).
Parameters
==========
k : power of divisors in the sum
for k = 0, 1:
``udivisor_sigma(n, 0)`` is equal to ``udivisor_count(n)``
``udivisor_sigma(n, 1)`` is equal to ``sum(udivisors(n))``
Default for k is 1.
Examples
========
>>> from sympy.ntheory.factor_ import udivisor_sigma
>>> udivisor_sigma(18, 0)
4
>>> udivisor_sigma(74, 1)
114
>>> udivisor_sigma(36, 3)
47450
>>> udivisor_sigma(111)
152
See Also
========
divisor_count, totient, divisors, udivisors, udivisor_count, divisor_sigma,
factorint
References
==========
.. [1] http://mathworld.wolfram.com/UnitaryDivisorFunction.html
"""
@classmethod
def eval(cls, n, k=1):
n = sympify(n)
k = sympify(k)
if n.is_prime:
return 1 + n**k
if n.is_Integer:
if n <= 0:
raise ValueError("n must be a positive integer")
else:
return Mul(*[1+p**(k*e) for p, e in factorint(n).items()])
class primenu(Function):
r"""
Calculate the number of distinct prime factors for a positive integer n.
If n's prime factorization is:
.. math ::
n = \prod_{i=1}^k p_i^{m_i},
then ``primenu(n)`` or `\nu(n)` is:
.. math ::
\nu(n) = k.
Examples
========
>>> from sympy.ntheory.factor_ import primenu
>>> primenu(1)
0
>>> primenu(30)
3
See Also
========
factorint
References
==========
.. [1] http://mathworld.wolfram.com/PrimeFactor.html
"""
@classmethod
def eval(cls, n):
n = sympify(n)
if n.is_Integer:
if n <= 0:
raise ValueError("n must be a positive integer")
else:
return len(factorint(n).keys())
class primeomega(Function):
r"""
Calculate the number of prime factors counting multiplicities for a
positive integer n.
If n's prime factorization is:
.. math ::
n = \prod_{i=1}^k p_i^{m_i},
then ``primeomega(n)`` or `\Omega(n)` is:
.. math ::
\Omega(n) = \sum_{i=1}^k m_i.
Examples
========
>>> from sympy.ntheory.factor_ import primeomega
>>> primeomega(1)
0
>>> primeomega(20)
3
See Also
========
factorint
References
==========
.. [1] http://mathworld.wolfram.com/PrimeFactor.html
"""
@classmethod
def eval(cls, n):
n = sympify(n)
if n.is_Integer:
if n <= 0:
raise ValueError("n must be a positive integer")
else:
return sum(factorint(n).values())
|
4f49c9a1196991b86ef24bd150fcf4f654f3b853161e53c0e2d7f83a7b044d54
|
from __future__ import print_function, division
from mpmath.libmp import (fzero,
from_man_exp, from_int, from_rational,
fone, fhalf, bitcount, to_int, to_str, mpf_mul, mpf_div, mpf_sub,
mpf_add, mpf_sqrt, mpf_pi, mpf_cosh_sinh, pi_fixed, mpf_cos,
mpf_sin)
from sympy.core.numbers import igcd
from sympy.core.compatibility import range
from .residue_ntheory import (_sqrt_mod_prime_power,
legendre_symbol, jacobi_symbol, is_quad_residue)
import math
def _pre():
maxn = 10**5
global _factor
global _totient
_factor = [0]*maxn
_totient = [1]*maxn
lim = int(maxn**0.5) + 5
for i in range(2, lim):
if _factor[i] == 0:
for j in range(i*i, maxn, i):
if _factor[j] == 0:
_factor[j] = i
for i in range(2, maxn):
if _factor[i] == 0:
_factor[i] = i
_totient[i] = i-1
continue
x = _factor[i]
y = i//x
if y % x == 0:
_totient[i] = _totient[y]*x
else:
_totient[i] = _totient[y]*(x - 1)
def _a(n, k, prec):
""" Compute the inner sum in HRR formula [1]_
References
==========
.. [1] http://msp.org/pjm/1956/6-1/pjm-v6-n1-p18-p.pdf
"""
if k == 1:
return fone
k1 = k
e = 0
p = _factor[k]
while k1 % p == 0:
k1 //= p
e += 1
k2 = k//k1 # k2 = p^e
v = 1 - 24*n
pi = mpf_pi(prec)
if k1 == 1:
# k = p^e
if p == 2:
mod = 8*k
v = mod + v % mod
v = (v*pow(9, k - 1, mod)) % mod
m = _sqrt_mod_prime_power(v, 2, e + 3)[0]
arg = mpf_div(mpf_mul(
from_int(4*m), pi, prec), from_int(mod), prec)
return mpf_mul(mpf_mul(
from_int((-1)**e*jacobi_symbol(m - 1, m)),
mpf_sqrt(from_int(k), prec), prec),
mpf_sin(arg, prec), prec)
if p == 3:
mod = 3*k
v = mod + v % mod
if e > 1:
v = (v*pow(64, k//3 - 1, mod)) % mod
m = _sqrt_mod_prime_power(v, 3, e + 1)[0]
arg = mpf_div(mpf_mul(from_int(4*m), pi, prec),
from_int(mod), prec)
return mpf_mul(mpf_mul(
from_int(2*(-1)**(e + 1)*legendre_symbol(m, 3)),
mpf_sqrt(from_int(k//3), prec), prec),
mpf_sin(arg, prec), prec)
v = k + v % k
if v % p == 0:
if e == 1:
return mpf_mul(
from_int(jacobi_symbol(3, k)),
mpf_sqrt(from_int(k), prec), prec)
return fzero
if not is_quad_residue(v, p):
return fzero
_phi = p**(e - 1)*(p - 1)
v = (v*pow(576, _phi - 1, k))
m = _sqrt_mod_prime_power(v, p, e)[0]
arg = mpf_div(
mpf_mul(from_int(4*m), pi, prec),
from_int(k), prec)
return mpf_mul(mpf_mul(
from_int(2*jacobi_symbol(3, k)),
mpf_sqrt(from_int(k), prec), prec),
mpf_cos(arg, prec), prec)
if p != 2 or e >= 3:
d1, d2 = igcd(k1, 24), igcd(k2, 24)
e = 24//(d1*d2)
n1 = ((d2*e*n + (k2**2 - 1)//d1)*
pow(e*k2*k2*d2, _totient[k1] - 1, k1)) % k1
n2 = ((d1*e*n + (k1**2 - 1)//d2)*
pow(e*k1*k1*d1, _totient[k2] - 1, k2)) % k2
return mpf_mul(_a(n1, k1, prec), _a(n2, k2, prec), prec)
if e == 2:
n1 = ((8*n + 5)*pow(128, _totient[k1] - 1, k1)) % k1
n2 = (4 + ((n - 2 - (k1**2 - 1)//8)*(k1**2)) % 4) % 4
return mpf_mul(mpf_mul(
from_int(-1),
_a(n1, k1, prec), prec),
_a(n2, k2, prec))
n1 = ((8*n + 1)*pow(32, _totient[k1] - 1, k1)) % k1
n2 = (2 + (n - (k1**2 - 1)//8) % 2) % 2
return mpf_mul(_a(n1, k1, prec), _a(n2, k2, prec), prec)
def _d(n, j, prec, sq23pi, sqrt8):
"""
Compute the sinh term in the outer sum of the HRR formula.
The constants sqrt(2/3*pi) and sqrt(8) must be precomputed.
"""
j = from_int(j)
pi = mpf_pi(prec)
a = mpf_div(sq23pi, j, prec)
b = mpf_sub(from_int(n), from_rational(1, 24, prec), prec)
c = mpf_sqrt(b, prec)
ch, sh = mpf_cosh_sinh(mpf_mul(a, c), prec)
D = mpf_div(
mpf_sqrt(j, prec),
mpf_mul(mpf_mul(sqrt8, b), pi), prec)
E = mpf_sub(mpf_mul(a, ch), mpf_div(sh, c, prec), prec)
return mpf_mul(D, E)
def npartitions(n, verbose=False):
"""
Calculate the partition function P(n), i.e. the number of ways that
n can be written as a sum of positive integers.
P(n) is computed using the Hardy-Ramanujan-Rademacher formula [1]_.
The correctness of this implementation has been tested through 10**10.
Examples
========
>>> from sympy.ntheory import npartitions
>>> npartitions(25)
1958
References
==========
.. [1] http://mathworld.wolfram.com/PartitionFunctionP.html
"""
n = int(n)
if n < 0:
return 0
if n <= 5:
return [1, 1, 2, 3, 5, 7][n]
if '_factor' not in globals():
_pre()
# Estimate number of bits in p(n). This formula could be tidied
pbits = int((
math.pi*(2*n/3.)**0.5 -
math.log(4*n))/math.log(10) + 1) * \
math.log(10, 2)
prec = p = int(pbits*1.1 + 100)
s = fzero
M = max(6, int(0.24*n**0.5 + 4))
if M > 10**5:
raise ValueError("Input too big") # Corresponds to n > 1.7e11
sq23pi = mpf_mul(mpf_sqrt(from_rational(2, 3, p), p), mpf_pi(p), p)
sqrt8 = mpf_sqrt(from_int(8), p)
for q in range(1, M):
a = _a(n, q, p)
d = _d(n, q, p, sq23pi, sqrt8)
s = mpf_add(s, mpf_mul(a, d), prec)
if verbose:
print("step", q, "of", M, to_str(a, 10), to_str(d, 10))
# On average, the terms decrease rapidly in magnitude.
# Dynamically reducing the precision greatly improves
# performance.
p = bitcount(abs(to_int(d))) + 50
return int(to_int(mpf_add(s, fhalf, prec)))
__all__ = ['npartitions']
|
55d5cf0f6227fa958c13a7585049346fd14431ca3376460e8cac354d6d5c3c7a
|
from sympy.combinatorics import Permutation
from sympy.combinatorics.util import _distribute_gens_by_base
from sympy.core.compatibility import range
rmul = Permutation.rmul
def _cmp_perm_lists(first, second):
"""
Compare two lists of permutations as sets.
This is used for testing purposes. Since the array form of a
permutation is currently a list, Permutation is not hashable
and cannot be put into a set.
Examples
========
>>> from sympy.combinatorics.permutations import Permutation
>>> from sympy.combinatorics.testutil import _cmp_perm_lists
>>> a = Permutation([0, 2, 3, 4, 1])
>>> b = Permutation([1, 2, 0, 4, 3])
>>> c = Permutation([3, 4, 0, 1, 2])
>>> ls1 = [a, b, c]
>>> ls2 = [b, c, a]
>>> _cmp_perm_lists(ls1, ls2)
True
"""
return {tuple(a) for a in first} == \
{tuple(a) for a in second}
def _naive_list_centralizer(self, other, af=False):
from sympy.combinatorics.perm_groups import PermutationGroup
"""
Return a list of elements for the centralizer of a subgroup/set/element.
This is a brute force implementation that goes over all elements of the
group and checks for membership in the centralizer. It is used to
test ``.centralizer()`` from ``sympy.combinatorics.perm_groups``.
Examples
========
>>> from sympy.combinatorics.testutil import _naive_list_centralizer
>>> from sympy.combinatorics.named_groups import DihedralGroup
>>> D = DihedralGroup(4)
>>> _naive_list_centralizer(D, D)
[Permutation([0, 1, 2, 3]), Permutation([2, 3, 0, 1])]
See Also
========
sympy.combinatorics.perm_groups.centralizer
"""
from sympy.combinatorics.permutations import _af_commutes_with
if hasattr(other, 'generators'):
elements = list(self.generate_dimino(af=True))
gens = [x._array_form for x in other.generators]
commutes_with_gens = lambda x: all(_af_commutes_with(x, gen) for gen in gens)
centralizer_list = []
if not af:
for element in elements:
if commutes_with_gens(element):
centralizer_list.append(Permutation._af_new(element))
else:
for element in elements:
if commutes_with_gens(element):
centralizer_list.append(element)
return centralizer_list
elif hasattr(other, 'getitem'):
return _naive_list_centralizer(self, PermutationGroup(other), af)
elif hasattr(other, 'array_form'):
return _naive_list_centralizer(self, PermutationGroup([other]), af)
def _verify_bsgs(group, base, gens):
"""
Verify the correctness of a base and strong generating set.
This is a naive implementation using the definition of a base and a strong
generating set relative to it. There are other procedures for
verifying a base and strong generating set, but this one will
serve for more robust testing.
Examples
========
>>> from sympy.combinatorics.named_groups import AlternatingGroup
>>> from sympy.combinatorics.testutil import _verify_bsgs
>>> A = AlternatingGroup(4)
>>> A.schreier_sims()
>>> _verify_bsgs(A, A.base, A.strong_gens)
True
See Also
========
sympy.combinatorics.perm_groups.PermutationGroup.schreier_sims
"""
from sympy.combinatorics.perm_groups import PermutationGroup
strong_gens_distr = _distribute_gens_by_base(base, gens)
current_stabilizer = group
for i in range(len(base)):
candidate = PermutationGroup(strong_gens_distr[i])
if current_stabilizer.order() != candidate.order():
return False
current_stabilizer = current_stabilizer.stabilizer(base[i])
if current_stabilizer.order() != 1:
return False
return True
def _verify_centralizer(group, arg, centr=None):
"""
Verify the centralizer of a group/set/element inside another group.
This is used for testing ``.centralizer()`` from
``sympy.combinatorics.perm_groups``
Examples
========
>>> from sympy.combinatorics.named_groups import (SymmetricGroup,
... AlternatingGroup)
>>> from sympy.combinatorics.perm_groups import PermutationGroup
>>> from sympy.combinatorics.permutations import Permutation
>>> from sympy.combinatorics.testutil import _verify_centralizer
>>> S = SymmetricGroup(5)
>>> A = AlternatingGroup(5)
>>> centr = PermutationGroup([Permutation([0, 1, 2, 3, 4])])
>>> _verify_centralizer(S, A, centr)
True
See Also
========
_naive_list_centralizer,
sympy.combinatorics.perm_groups.PermutationGroup.centralizer,
_cmp_perm_lists
"""
if centr is None:
centr = group.centralizer(arg)
centr_list = list(centr.generate_dimino(af=True))
centr_list_naive = _naive_list_centralizer(group, arg, af=True)
return _cmp_perm_lists(centr_list, centr_list_naive)
def _verify_normal_closure(group, arg, closure=None):
from sympy.combinatorics.perm_groups import PermutationGroup
"""
Verify the normal closure of a subgroup/subset/element in a group.
This is used to test
sympy.combinatorics.perm_groups.PermutationGroup.normal_closure
Examples
========
>>> from sympy.combinatorics.named_groups import (SymmetricGroup,
... AlternatingGroup)
>>> from sympy.combinatorics.testutil import _verify_normal_closure
>>> S = SymmetricGroup(3)
>>> A = AlternatingGroup(3)
>>> _verify_normal_closure(S, A, closure=A)
True
See Also
========
sympy.combinatorics.perm_groups.PermutationGroup.normal_closure
"""
if closure is None:
closure = group.normal_closure(arg)
conjugates = set()
if hasattr(arg, 'generators'):
subgr_gens = arg.generators
elif hasattr(arg, '__getitem__'):
subgr_gens = arg
elif hasattr(arg, 'array_form'):
subgr_gens = [arg]
for el in group.generate_dimino():
for gen in subgr_gens:
conjugates.add(gen ^ el)
naive_closure = PermutationGroup(list(conjugates))
return closure.is_subgroup(naive_closure)
def canonicalize_naive(g, dummies, sym, *v):
"""
Canonicalize tensor formed by tensors of the different types
g permutation representing the tensor
dummies list of dummy indices
msym symmetry of the metric
v is a list of (base_i, gens_i, n_i, sym_i) for tensors of type `i`
base_i, gens_i BSGS for tensors of this type
n_i number ot tensors of type `i`
sym_i symmetry under exchange of two component tensors of type `i`
None no symmetry
0 commuting
1 anticommuting
Return 0 if the tensor is zero, else return the array form of
the permutation representing the canonical form of the tensor.
Examples
========
>>> from sympy.combinatorics.testutil import canonicalize_naive
>>> from sympy.combinatorics.tensor_can import get_symmetric_group_sgs
>>> from sympy.combinatorics import Permutation, PermutationGroup
>>> g = Permutation([1, 3, 2, 0, 4, 5])
>>> base2, gens2 = get_symmetric_group_sgs(2)
>>> canonicalize_naive(g, [2, 3], 0, (base2, gens2, 2, 0))
[0, 2, 1, 3, 4, 5]
"""
from sympy.combinatorics.perm_groups import PermutationGroup
from sympy.combinatorics.tensor_can import gens_products, dummy_sgs
from sympy.combinatorics.permutations import Permutation, _af_rmul
v1 = []
for i in range(len(v)):
base_i, gens_i, n_i, sym_i = v[i]
v1.append((base_i, gens_i, [[]]*n_i, sym_i))
size, sbase, sgens = gens_products(*v1)
dgens = dummy_sgs(dummies, sym, size-2)
if isinstance(sym, int):
num_types = 1
dummies = [dummies]
sym = [sym]
else:
num_types = len(sym)
dgens = []
for i in range(num_types):
dgens.extend(dummy_sgs(dummies[i], sym[i], size - 2))
S = PermutationGroup(sgens)
D = PermutationGroup([Permutation(x) for x in dgens])
dlist = list(D.generate(af=True))
g = g.array_form
st = set()
for s in S.generate(af=True):
h = _af_rmul(g, s)
for d in dlist:
q = tuple(_af_rmul(d, h))
st.add(q)
a = list(st)
a.sort()
prev = (0,)*size
for h in a:
if h[:-2] == prev[:-2]:
if h[-1] != prev[-1]:
return 0
prev = h
return list(a[0])
def graph_certificate(gr):
"""
Return a certificate for the graph
gr adjacency list
The graph is assumed to be unoriented and without
external lines.
Associate to each vertex of the graph a symmetric tensor with
number of indices equal to the degree of the vertex; indices
are contracted when they correspond to the same line of the graph.
The canonical form of the tensor gives a certificate for the graph.
This is not an efficient algorithm to get the certificate of a graph.
Examples
========
>>> from sympy.combinatorics.testutil import graph_certificate
>>> gr1 = {0:[1, 2, 3, 5], 1:[0, 2, 4], 2:[0, 1, 3, 4], 3:[0, 2, 4], 4:[1, 2, 3, 5], 5:[0, 4]}
>>> gr2 = {0:[1, 5], 1:[0, 2, 3, 4], 2:[1, 3, 5], 3:[1, 2, 4, 5], 4:[1, 3, 5], 5:[0, 2, 3, 4]}
>>> c1 = graph_certificate(gr1)
>>> c2 = graph_certificate(gr2)
>>> c1
[0, 2, 4, 6, 1, 8, 10, 12, 3, 14, 16, 18, 5, 9, 15, 7, 11, 17, 13, 19, 20, 21]
>>> c1 == c2
True
"""
from sympy.combinatorics.permutations import _af_invert
from sympy.combinatorics.tensor_can import get_symmetric_group_sgs, canonicalize
items = list(gr.items())
items.sort(key=lambda x: len(x[1]), reverse=True)
pvert = [x[0] for x in items]
pvert = _af_invert(pvert)
# the indices of the tensor are twice the number of lines of the graph
num_indices = 0
for v, neigh in items:
num_indices += len(neigh)
# associate to each vertex its indices; for each line
# between two vertices assign the
# even index to the vertex which comes first in items,
# the odd index to the other vertex
vertices = [[] for i in items]
i = 0
for v, neigh in items:
for v2 in neigh:
if pvert[v] < pvert[v2]:
vertices[pvert[v]].append(i)
vertices[pvert[v2]].append(i+1)
i += 2
g = []
for v in vertices:
g.extend(v)
assert len(g) == num_indices
g += [num_indices, num_indices + 1]
size = num_indices + 2
assert sorted(g) == list(range(size))
g = Permutation(g)
vlen = [0]*(len(vertices[0])+1)
for neigh in vertices:
vlen[len(neigh)] += 1
v = []
for i in range(len(vlen)):
n = vlen[i]
if n:
base, gens = get_symmetric_group_sgs(i)
v.append((base, gens, n, 0))
v.reverse()
dummies = list(range(num_indices))
can = canonicalize(g, dummies, 0, *v)
return can
|
6aefcc3e483c0e8cb0417c7d326684b7b6511342dfd9d749c8feb38571355472
|
from __future__ import print_function, division
from random import randrange, choice
from math import log
from sympy.combinatorics import Permutation
from sympy.combinatorics.permutations import (_af_commutes_with, _af_invert,
_af_rmul, _af_rmuln, _af_pow, Cycle)
from sympy.combinatorics.util import (_check_cycles_alt_sym,
_distribute_gens_by_base, _orbits_transversals_from_bsgs,
_handle_precomputed_bsgs, _base_ordering, _strong_gens_from_distr,
_strip, _strip_af)
from sympy.core import Basic
from sympy.core.compatibility import range
from sympy.functions.combinatorial.factorials import factorial
from sympy.ntheory import sieve
from sympy.utilities.iterables import has_variety, is_sequence, uniq
from sympy.utilities.randtest import _randrange
from itertools import islice
rmul = Permutation.rmul_with_af
_af_new = Permutation._af_new
class PermutationGroup(Basic):
"""The class defining a Permutation group.
PermutationGroup([p1, p2, ..., pn]) returns the permutation group
generated by the list of permutations. This group can be supplied
to Polyhedron if one desires to decorate the elements to which the
indices of the permutation refer.
Examples
========
>>> from sympy.combinatorics import Permutation
>>> Permutation.print_cyclic = True
>>> from sympy.combinatorics.permutations import Cycle
>>> from sympy.combinatorics.polyhedron import Polyhedron
>>> from sympy.combinatorics.perm_groups import PermutationGroup
The permutations corresponding to motion of the front, right and
bottom face of a 2x2 Rubik's cube are defined:
>>> F = Permutation(2, 19, 21, 8)(3, 17, 20, 10)(4, 6, 7, 5)
>>> R = Permutation(1, 5, 21, 14)(3, 7, 23, 12)(8, 10, 11, 9)
>>> D = Permutation(6, 18, 14, 10)(7, 19, 15, 11)(20, 22, 23, 21)
These are passed as permutations to PermutationGroup:
>>> G = PermutationGroup(F, R, D)
>>> G.order()
3674160
The group can be supplied to a Polyhedron in order to track the
objects being moved. An example involving the 2x2 Rubik's cube is
given there, but here is a simple demonstration:
>>> a = Permutation(2, 1)
>>> b = Permutation(1, 0)
>>> G = PermutationGroup(a, b)
>>> P = Polyhedron(list('ABC'), pgroup=G)
>>> P.corners
(A, B, C)
>>> P.rotate(0) # apply permutation 0
>>> P.corners
(A, C, B)
>>> P.reset()
>>> P.corners
(A, B, C)
Or one can make a permutation as a product of selected permutations
and apply them to an iterable directly:
>>> P10 = G.make_perm([0, 1])
>>> P10('ABC')
['C', 'A', 'B']
See Also
========
sympy.combinatorics.polyhedron.Polyhedron,
sympy.combinatorics.permutations.Permutation
References
==========
.. [1] Holt, D., Eick, B., O'Brien, E.
"Handbook of Computational Group Theory"
.. [2] Seress, A.
"Permutation Group Algorithms"
.. [3] https://en.wikipedia.org/wiki/Schreier_vector
.. [4] https://en.wikipedia.org/wiki/Nielsen_transformation#Product_replacement_algorithm
.. [5] Frank Celler, Charles R.Leedham-Green, Scott H.Murray,
Alice C.Niemeyer, and E.A.O'Brien. "Generating Random
Elements of a Finite Group"
.. [6] https://en.wikipedia.org/wiki/Block_%28permutation_group_theory%29
.. [7] http://www.algorithmist.com/index.php/Union_Find
.. [8] https://en.wikipedia.org/wiki/Multiply_transitive_group#Multiply_transitive_groups
.. [9] https://en.wikipedia.org/wiki/Center_%28group_theory%29
.. [10] https://en.wikipedia.org/wiki/Centralizer_and_normalizer
.. [11] http://groupprops.subwiki.org/wiki/Derived_subgroup
.. [12] https://en.wikipedia.org/wiki/Nilpotent_group
.. [13] http://www.math.colostate.edu/~hulpke/CGT/cgtnotes.pdf
"""
is_group = True
def __new__(cls, *args, **kwargs):
"""The default constructor. Accepts Cycle and Permutation forms.
Removes duplicates unless ``dups`` keyword is ``False``.
"""
if not args:
args = [Permutation()]
else:
args = list(args[0] if is_sequence(args[0]) else args)
if not args:
args = [Permutation()]
if any(isinstance(a, Cycle) for a in args):
args = [Permutation(a) for a in args]
if has_variety(a.size for a in args):
degree = kwargs.pop('degree', None)
if degree is None:
degree = max(a.size for a in args)
for i in range(len(args)):
if args[i].size != degree:
args[i] = Permutation(args[i], size=degree)
if kwargs.pop('dups', True):
args = list(uniq([_af_new(list(a)) for a in args]))
if len(args) > 1:
args = [g for g in args if not g.is_identity]
obj = Basic.__new__(cls, *args, **kwargs)
obj._generators = args
obj._order = None
obj._center = []
obj._is_abelian = None
obj._is_transitive = None
obj._is_sym = None
obj._is_alt = None
obj._is_primitive = None
obj._is_nilpotent = None
obj._is_solvable = None
obj._is_trivial = None
obj._transitivity_degree = None
obj._max_div = None
obj._r = len(obj._generators)
obj._degree = obj._generators[0].size
# these attributes are assigned after running schreier_sims
obj._base = []
obj._strong_gens = []
obj._strong_gens_slp = []
obj._basic_orbits = []
obj._transversals = []
obj._transversal_slp = []
# these attributes are assigned after running _random_pr_init
obj._random_gens = []
# finite presentation of the group as an instance of `FpGroup`
obj._fp_presentation = None
return obj
def __getitem__(self, i):
return self._generators[i]
def __contains__(self, i):
"""Return ``True`` if `i` is contained in PermutationGroup.
Examples
========
>>> from sympy.combinatorics import Permutation, PermutationGroup
>>> p = Permutation(1, 2, 3)
>>> Permutation(3) in PermutationGroup(p)
True
"""
if not isinstance(i, Permutation):
raise TypeError("A PermutationGroup contains only Permutations as "
"elements, not elements of type %s" % type(i))
return self.contains(i)
def __len__(self):
return len(self._generators)
def __eq__(self, other):
"""Return ``True`` if PermutationGroup generated by elements in the
group are same i.e they represent the same PermutationGroup.
Examples
========
>>> from sympy.combinatorics import Permutation
>>> from sympy.combinatorics.perm_groups import PermutationGroup
>>> p = Permutation(0, 1, 2, 3, 4, 5)
>>> G = PermutationGroup([p, p**2])
>>> H = PermutationGroup([p**2, p])
>>> G.generators == H.generators
False
>>> G == H
True
"""
if not isinstance(other, PermutationGroup):
return False
set_self_gens = set(self.generators)
set_other_gens = set(other.generators)
# before reaching the general case there are also certain
# optimisation and obvious cases requiring less or no actual
# computation.
if set_self_gens == set_other_gens:
return True
# in the most general case it will check that each generator of
# one group belongs to the other PermutationGroup and vice-versa
for gen1 in set_self_gens:
if not other.contains(gen1):
return False
for gen2 in set_other_gens:
if not self.contains(gen2):
return False
return True
def __hash__(self):
return super(PermutationGroup, self).__hash__()
def __mul__(self, other):
"""Return the direct product of two permutation groups as a permutation
group.
This implementation realizes the direct product by shifting the index
set for the generators of the second group: so if we have `G` acting
on `n1` points and `H` acting on `n2` points, `G*H` acts on `n1 + n2`
points.
Examples
========
>>> from sympy.combinatorics.perm_groups import PermutationGroup
>>> from sympy.combinatorics.named_groups import CyclicGroup
>>> G = CyclicGroup(5)
>>> H = G*G
>>> H
PermutationGroup([
(9)(0 1 2 3 4),
(5 6 7 8 9)])
>>> H.order()
25
"""
gens1 = [perm._array_form for perm in self.generators]
gens2 = [perm._array_form for perm in other.generators]
n1 = self._degree
n2 = other._degree
start = list(range(n1))
end = list(range(n1, n1 + n2))
for i in range(len(gens2)):
gens2[i] = [x + n1 for x in gens2[i]]
gens2 = [start + gen for gen in gens2]
gens1 = [gen + end for gen in gens1]
together = gens1 + gens2
gens = [_af_new(x) for x in together]
return PermutationGroup(gens)
def _random_pr_init(self, r, n, _random_prec_n=None):
r"""Initialize random generators for the product replacement algorithm.
The implementation uses a modification of the original product
replacement algorithm due to Leedham-Green, as described in [1],
pp. 69-71; also, see [2], pp. 27-29 for a detailed theoretical
analysis of the original product replacement algorithm, and [4].
The product replacement algorithm is used for producing random,
uniformly distributed elements of a group `G` with a set of generators
`S`. For the initialization ``_random_pr_init``, a list ``R`` of
`\max\{r, |S|\}` group generators is created as the attribute
``G._random_gens``, repeating elements of `S` if necessary, and the
identity element of `G` is appended to ``R`` - we shall refer to this
last element as the accumulator. Then the function ``random_pr()``
is called ``n`` times, randomizing the list ``R`` while preserving
the generation of `G` by ``R``. The function ``random_pr()`` itself
takes two random elements ``g, h`` among all elements of ``R`` but
the accumulator and replaces ``g`` with a randomly chosen element
from `\{gh, g(~h), hg, (~h)g\}`. Then the accumulator is multiplied
by whatever ``g`` was replaced by. The new value of the accumulator is
then returned by ``random_pr()``.
The elements returned will eventually (for ``n`` large enough) become
uniformly distributed across `G` ([5]). For practical purposes however,
the values ``n = 50, r = 11`` are suggested in [1].
Notes
=====
THIS FUNCTION HAS SIDE EFFECTS: it changes the attribute
self._random_gens
See Also
========
random_pr
"""
deg = self.degree
random_gens = [x._array_form for x in self.generators]
k = len(random_gens)
if k < r:
for i in range(k, r):
random_gens.append(random_gens[i - k])
acc = list(range(deg))
random_gens.append(acc)
self._random_gens = random_gens
# handle randomized input for testing purposes
if _random_prec_n is None:
for i in range(n):
self.random_pr()
else:
for i in range(n):
self.random_pr(_random_prec=_random_prec_n[i])
def _union_find_merge(self, first, second, ranks, parents, not_rep):
"""Merges two classes in a union-find data structure.
Used in the implementation of Atkinson's algorithm as suggested in [1],
pp. 83-87. The class merging process uses union by rank as an
optimization. ([7])
Notes
=====
THIS FUNCTION HAS SIDE EFFECTS: the list of class representatives,
``parents``, the list of class sizes, ``ranks``, and the list of
elements that are not representatives, ``not_rep``, are changed due to
class merging.
See Also
========
minimal_block, _union_find_rep
References
==========
.. [1] Holt, D., Eick, B., O'Brien, E.
"Handbook of computational group theory"
.. [7] http://www.algorithmist.com/index.php/Union_Find
"""
rep_first = self._union_find_rep(first, parents)
rep_second = self._union_find_rep(second, parents)
if rep_first != rep_second:
# union by rank
if ranks[rep_first] >= ranks[rep_second]:
new_1, new_2 = rep_first, rep_second
else:
new_1, new_2 = rep_second, rep_first
total_rank = ranks[new_1] + ranks[new_2]
if total_rank > self.max_div:
return -1
parents[new_2] = new_1
ranks[new_1] = total_rank
not_rep.append(new_2)
return 1
return 0
def _union_find_rep(self, num, parents):
"""Find representative of a class in a union-find data structure.
Used in the implementation of Atkinson's algorithm as suggested in [1],
pp. 83-87. After the representative of the class to which ``num``
belongs is found, path compression is performed as an optimization
([7]).
Notes
=====
THIS FUNCTION HAS SIDE EFFECTS: the list of class representatives,
``parents``, is altered due to path compression.
See Also
========
minimal_block, _union_find_merge
References
==========
.. [1] Holt, D., Eick, B., O'Brien, E.
"Handbook of computational group theory"
.. [7] http://www.algorithmist.com/index.php/Union_Find
"""
rep, parent = num, parents[num]
while parent != rep:
rep = parent
parent = parents[rep]
# path compression
temp, parent = num, parents[num]
while parent != rep:
parents[temp] = rep
temp = parent
parent = parents[temp]
return rep
@property
def base(self):
"""Return a base from the Schreier-Sims algorithm.
For a permutation group `G`, a base is a sequence of points
`B = (b_1, b_2, ..., b_k)` such that no element of `G` apart
from the identity fixes all the points in `B`. The concepts of
a base and strong generating set and their applications are
discussed in depth in [1], pp. 87-89 and [2], pp. 55-57.
An alternative way to think of `B` is that it gives the
indices of the stabilizer cosets that contain more than the
identity permutation.
Examples
========
>>> from sympy.combinatorics import Permutation, PermutationGroup
>>> G = PermutationGroup([Permutation(0, 1, 3)(2, 4)])
>>> G.base
[0, 2]
See Also
========
strong_gens, basic_transversals, basic_orbits, basic_stabilizers
"""
if self._base == []:
self.schreier_sims()
return self._base
def baseswap(self, base, strong_gens, pos, randomized=False,
transversals=None, basic_orbits=None, strong_gens_distr=None):
r"""Swap two consecutive base points in base and strong generating set.
If a base for a group `G` is given by `(b_1, b_2, ..., b_k)`, this
function returns a base `(b_1, b_2, ..., b_{i+1}, b_i, ..., b_k)`,
where `i` is given by ``pos``, and a strong generating set relative
to that base. The original base and strong generating set are not
modified.
The randomized version (default) is of Las Vegas type.
Parameters
==========
base, strong_gens
The base and strong generating set.
pos
The position at which swapping is performed.
randomized
A switch between randomized and deterministic version.
transversals
The transversals for the basic orbits, if known.
basic_orbits
The basic orbits, if known.
strong_gens_distr
The strong generators distributed by basic stabilizers, if known.
Returns
=======
(base, strong_gens)
``base`` is the new base, and ``strong_gens`` is a generating set
relative to it.
Examples
========
>>> from sympy.combinatorics.named_groups import SymmetricGroup
>>> from sympy.combinatorics.testutil import _verify_bsgs
>>> from sympy.combinatorics.perm_groups import PermutationGroup
>>> S = SymmetricGroup(4)
>>> S.schreier_sims()
>>> S.base
[0, 1, 2]
>>> base, gens = S.baseswap(S.base, S.strong_gens, 1, randomized=False)
>>> base, gens
([0, 2, 1],
[(0 1 2 3), (3)(0 1), (1 3 2),
(2 3), (1 3)])
check that base, gens is a BSGS
>>> S1 = PermutationGroup(gens)
>>> _verify_bsgs(S1, base, gens)
True
See Also
========
schreier_sims
Notes
=====
The deterministic version of the algorithm is discussed in
[1], pp. 102-103; the randomized version is discussed in [1], p.103, and
[2], p.98. It is of Las Vegas type.
Notice that [1] contains a mistake in the pseudocode and
discussion of BASESWAP: on line 3 of the pseudocode,
`|\beta_{i+1}^{\left\langle T\right\rangle}|` should be replaced by
`|\beta_{i}^{\left\langle T\right\rangle}|`, and the same for the
discussion of the algorithm.
"""
# construct the basic orbits, generators for the stabilizer chain
# and transversal elements from whatever was provided
transversals, basic_orbits, strong_gens_distr = \
_handle_precomputed_bsgs(base, strong_gens, transversals,
basic_orbits, strong_gens_distr)
base_len = len(base)
degree = self.degree
# size of orbit of base[pos] under the stabilizer we seek to insert
# in the stabilizer chain at position pos + 1
size = len(basic_orbits[pos])*len(basic_orbits[pos + 1]) \
//len(_orbit(degree, strong_gens_distr[pos], base[pos + 1]))
# initialize the wanted stabilizer by a subgroup
if pos + 2 > base_len - 1:
T = []
else:
T = strong_gens_distr[pos + 2][:]
# randomized version
if randomized is True:
stab_pos = PermutationGroup(strong_gens_distr[pos])
schreier_vector = stab_pos.schreier_vector(base[pos + 1])
# add random elements of the stabilizer until they generate it
while len(_orbit(degree, T, base[pos])) != size:
new = stab_pos.random_stab(base[pos + 1],
schreier_vector=schreier_vector)
T.append(new)
# deterministic version
else:
Gamma = set(basic_orbits[pos])
Gamma.remove(base[pos])
if base[pos + 1] in Gamma:
Gamma.remove(base[pos + 1])
# add elements of the stabilizer until they generate it by
# ruling out member of the basic orbit of base[pos] along the way
while len(_orbit(degree, T, base[pos])) != size:
gamma = next(iter(Gamma))
x = transversals[pos][gamma]
temp = x._array_form.index(base[pos + 1]) # (~x)(base[pos + 1])
if temp not in basic_orbits[pos + 1]:
Gamma = Gamma - _orbit(degree, T, gamma)
else:
y = transversals[pos + 1][temp]
el = rmul(x, y)
if el(base[pos]) not in _orbit(degree, T, base[pos]):
T.append(el)
Gamma = Gamma - _orbit(degree, T, base[pos])
# build the new base and strong generating set
strong_gens_new_distr = strong_gens_distr[:]
strong_gens_new_distr[pos + 1] = T
base_new = base[:]
base_new[pos], base_new[pos + 1] = base_new[pos + 1], base_new[pos]
strong_gens_new = _strong_gens_from_distr(strong_gens_new_distr)
for gen in T:
if gen not in strong_gens_new:
strong_gens_new.append(gen)
return base_new, strong_gens_new
@property
def basic_orbits(self):
"""
Return the basic orbits relative to a base and strong generating set.
If `(b_1, b_2, ..., b_k)` is a base for a group `G`, and
`G^{(i)} = G_{b_1, b_2, ..., b_{i-1}}` is the ``i``-th basic stabilizer
(so that `G^{(1)} = G`), the ``i``-th basic orbit relative to this base
is the orbit of `b_i` under `G^{(i)}`. See [1], pp. 87-89 for more
information.
Examples
========
>>> from sympy.combinatorics.named_groups import SymmetricGroup
>>> S = SymmetricGroup(4)
>>> S.basic_orbits
[[0, 1, 2, 3], [1, 2, 3], [2, 3]]
See Also
========
base, strong_gens, basic_transversals, basic_stabilizers
"""
if self._basic_orbits == []:
self.schreier_sims()
return self._basic_orbits
@property
def basic_stabilizers(self):
"""
Return a chain of stabilizers relative to a base and strong generating
set.
The ``i``-th basic stabilizer `G^{(i)}` relative to a base
`(b_1, b_2, ..., b_k)` is `G_{b_1, b_2, ..., b_{i-1}}`. For more
information, see [1], pp. 87-89.
Examples
========
>>> from sympy.combinatorics.named_groups import AlternatingGroup
>>> A = AlternatingGroup(4)
>>> A.schreier_sims()
>>> A.base
[0, 1]
>>> for g in A.basic_stabilizers:
... print(g)
...
PermutationGroup([
(3)(0 1 2),
(1 2 3)])
PermutationGroup([
(1 2 3)])
See Also
========
base, strong_gens, basic_orbits, basic_transversals
"""
if self._transversals == []:
self.schreier_sims()
strong_gens = self._strong_gens
base = self._base
if not base: # e.g. if self is trivial
return []
strong_gens_distr = _distribute_gens_by_base(base, strong_gens)
basic_stabilizers = []
for gens in strong_gens_distr:
basic_stabilizers.append(PermutationGroup(gens))
return basic_stabilizers
@property
def basic_transversals(self):
"""
Return basic transversals relative to a base and strong generating set.
The basic transversals are transversals of the basic orbits. They
are provided as a list of dictionaries, each dictionary having
keys - the elements of one of the basic orbits, and values - the
corresponding transversal elements. See [1], pp. 87-89 for more
information.
Examples
========
>>> from sympy.combinatorics.named_groups import AlternatingGroup
>>> A = AlternatingGroup(4)
>>> A.basic_transversals
[{0: (3), 1: (3)(0 1 2), 2: (3)(0 2 1), 3: (0 3 1)}, {1: (3), 2: (1 2 3), 3: (1 3 2)}]
See Also
========
strong_gens, base, basic_orbits, basic_stabilizers
"""
if self._transversals == []:
self.schreier_sims()
return self._transversals
def coset_transversal(self, H):
"""Return a transversal of the right cosets of self by its subgroup H
using the second method described in [1], Subsection 4.6.7
"""
if not H.is_subgroup(self):
raise ValueError("The argument must be a subgroup")
if H.order() == 1:
return self._elements
self._schreier_sims(base=H.base) # make G.base an extension of H.base
base = self.base
base_ordering = _base_ordering(base, self.degree)
identity = Permutation(self.degree - 1)
transversals = self.basic_transversals[:]
# transversals is a list of dictionaries. Get rid of the keys
# so that it is a list of lists and sort each list in
# the increasing order of base[l]^x
for l, t in enumerate(transversals):
transversals[l] = sorted(t.values(),
key = lambda x: base_ordering[base[l]^x])
orbits = H.basic_orbits
h_stabs = H.basic_stabilizers
g_stabs = self.basic_stabilizers
indices = [x.order()//y.order() for x, y in zip(g_stabs, h_stabs)]
# T^(l) should be a right transversal of H^(l) in G^(l) for
# 1<=l<=len(base). While H^(l) is the trivial group, T^(l)
# contains all the elements of G^(l) so we might just as well
# start with l = len(h_stabs)-1
if len(g_stabs) > len(h_stabs):
T = g_stabs[len(h_stabs)]._elements
else:
T = [identity]
l = len(h_stabs)-1
t_len = len(T)
while l > -1:
T_next = []
for u in transversals[l]:
if u == identity:
continue
b = base_ordering[base[l]^u]
for t in T:
p = t*u
if all([base_ordering[h^p] >= b for h in orbits[l]]):
T_next.append(p)
if t_len + len(T_next) == indices[l]:
break
if t_len + len(T_next) == indices[l]:
break
T += T_next
t_len += len(T_next)
l -= 1
T.remove(identity)
T = [identity] + T
return T
def _coset_representative(self, g, H):
"""Return the representative of Hg from the transversal that
would be computed by `self.coset_transversal(H)`.
"""
if H.order() == 1:
return g
# The base of self must be an extension of H.base.
if not(self.base[:len(H.base)] == H.base):
self._schreier_sims(base=H.base)
orbits = H.basic_orbits[:]
h_transversals = [list(_.values()) for _ in H.basic_transversals]
transversals = [list(_.values()) for _ in self.basic_transversals]
base = self.base
base_ordering = _base_ordering(base, self.degree)
def step(l, x):
gamma = sorted(orbits[l], key = lambda y: base_ordering[y^x])[0]
i = [base[l]^h for h in h_transversals[l]].index(gamma)
x = h_transversals[l][i]*x
if l < len(orbits)-1:
for u in transversals[l]:
if base[l]^u == base[l]^x:
break
x = step(l+1, x*u**-1)*u
return x
return step(0, g)
def coset_table(self, H):
"""Return the standardised (right) coset table of self in H as
a list of lists.
"""
# Maybe this should be made to return an instance of CosetTable
# from fp_groups.py but the class would need to be changed first
# to be compatible with PermutationGroups
from itertools import chain, product
if not H.is_subgroup(self):
raise ValueError("The argument must be a subgroup")
T = self.coset_transversal(H)
n = len(T)
A = list(chain.from_iterable((gen, gen**-1)
for gen in self.generators))
table = []
for i in range(n):
row = [self._coset_representative(T[i]*x, H) for x in A]
row = [T.index(r) for r in row]
table.append(row)
# standardize (this is the same as the algorithm used in coset_table)
# If CosetTable is made compatible with PermutationGroups, this
# should be replaced by table.standardize()
A = range(len(A))
gamma = 1
for alpha, a in product(range(n), A):
beta = table[alpha][a]
if beta >= gamma:
if beta > gamma:
for x in A:
z = table[gamma][x]
table[gamma][x] = table[beta][x]
table[beta][x] = z
for i in range(n):
if table[i][x] == beta:
table[i][x] = gamma
elif table[i][x] == gamma:
table[i][x] = beta
gamma += 1
if gamma >= n-1:
return table
def center(self):
r"""
Return the center of a permutation group.
The center for a group `G` is defined as
`Z(G) = \{z\in G | \forall g\in G, zg = gz \}`,
the set of elements of `G` that commute with all elements of `G`.
It is equal to the centralizer of `G` inside `G`, and is naturally a
subgroup of `G` ([9]).
Examples
========
>>> from sympy.combinatorics.perm_groups import PermutationGroup
>>> from sympy.combinatorics.named_groups import DihedralGroup
>>> D = DihedralGroup(4)
>>> G = D.center()
>>> G.order()
2
See Also
========
centralizer
Notes
=====
This is a naive implementation that is a straightforward application
of ``.centralizer()``
"""
return self.centralizer(self)
def centralizer(self, other):
r"""
Return the centralizer of a group/set/element.
The centralizer of a set of permutations ``S`` inside
a group ``G`` is the set of elements of ``G`` that commute with all
elements of ``S``::
`C_G(S) = \{ g \in G | gs = sg \forall s \in S\}` ([10])
Usually, ``S`` is a subset of ``G``, but if ``G`` is a proper subgroup of
the full symmetric group, we allow for ``S`` to have elements outside
``G``.
It is naturally a subgroup of ``G``; the centralizer of a permutation
group is equal to the centralizer of any set of generators for that
group, since any element commuting with the generators commutes with
any product of the generators.
Parameters
==========
other
a permutation group/list of permutations/single permutation
Examples
========
>>> from sympy.combinatorics.named_groups import (SymmetricGroup,
... CyclicGroup)
>>> S = SymmetricGroup(6)
>>> C = CyclicGroup(6)
>>> H = S.centralizer(C)
>>> H.is_subgroup(C)
True
See Also
========
subgroup_search
Notes
=====
The implementation is an application of ``.subgroup_search()`` with
tests using a specific base for the group ``G``.
"""
if hasattr(other, 'generators'):
if other.is_trivial or self.is_trivial:
return self
degree = self.degree
identity = _af_new(list(range(degree)))
orbits = other.orbits()
num_orbits = len(orbits)
orbits.sort(key=lambda x: -len(x))
long_base = []
orbit_reps = [None]*num_orbits
orbit_reps_indices = [None]*num_orbits
orbit_descr = [None]*degree
for i in range(num_orbits):
orbit = list(orbits[i])
orbit_reps[i] = orbit[0]
orbit_reps_indices[i] = len(long_base)
for point in orbit:
orbit_descr[point] = i
long_base = long_base + orbit
base, strong_gens = self.schreier_sims_incremental(base=long_base)
strong_gens_distr = _distribute_gens_by_base(base, strong_gens)
i = 0
for i in range(len(base)):
if strong_gens_distr[i] == [identity]:
break
base = base[:i]
base_len = i
for j in range(num_orbits):
if base[base_len - 1] in orbits[j]:
break
rel_orbits = orbits[: j + 1]
num_rel_orbits = len(rel_orbits)
transversals = [None]*num_rel_orbits
for j in range(num_rel_orbits):
rep = orbit_reps[j]
transversals[j] = dict(
other.orbit_transversal(rep, pairs=True))
trivial_test = lambda x: True
tests = [None]*base_len
for l in range(base_len):
if base[l] in orbit_reps:
tests[l] = trivial_test
else:
def test(computed_words, l=l):
g = computed_words[l]
rep_orb_index = orbit_descr[base[l]]
rep = orbit_reps[rep_orb_index]
im = g._array_form[base[l]]
im_rep = g._array_form[rep]
tr_el = transversals[rep_orb_index][base[l]]
# using the definition of transversal,
# base[l]^g = rep^(tr_el*g);
# if g belongs to the centralizer, then
# base[l]^g = (rep^g)^tr_el
return im == tr_el._array_form[im_rep]
tests[l] = test
def prop(g):
return [rmul(g, gen) for gen in other.generators] == \
[rmul(gen, g) for gen in other.generators]
return self.subgroup_search(prop, base=base,
strong_gens=strong_gens, tests=tests)
elif hasattr(other, '__getitem__'):
gens = list(other)
return self.centralizer(PermutationGroup(gens))
elif hasattr(other, 'array_form'):
return self.centralizer(PermutationGroup([other]))
def commutator(self, G, H):
"""
Return the commutator of two subgroups.
For a permutation group ``K`` and subgroups ``G``, ``H``, the
commutator of ``G`` and ``H`` is defined as the group generated
by all the commutators `[g, h] = hgh^{-1}g^{-1}` for ``g`` in ``G`` and
``h`` in ``H``. It is naturally a subgroup of ``K`` ([1], p.27).
Examples
========
>>> from sympy.combinatorics.named_groups import (SymmetricGroup,
... AlternatingGroup)
>>> S = SymmetricGroup(5)
>>> A = AlternatingGroup(5)
>>> G = S.commutator(S, A)
>>> G.is_subgroup(A)
True
See Also
========
derived_subgroup
Notes
=====
The commutator of two subgroups `H, G` is equal to the normal closure
of the commutators of all the generators, i.e. `hgh^{-1}g^{-1}` for `h`
a generator of `H` and `g` a generator of `G` ([1], p.28)
"""
ggens = G.generators
hgens = H.generators
commutators = []
for ggen in ggens:
for hgen in hgens:
commutator = rmul(hgen, ggen, ~hgen, ~ggen)
if commutator not in commutators:
commutators.append(commutator)
res = self.normal_closure(commutators)
return res
def coset_factor(self, g, factor_index=False):
"""Return ``G``'s (self's) coset factorization of ``g``
If ``g`` is an element of ``G`` then it can be written as the product
of permutations drawn from the Schreier-Sims coset decomposition,
The permutations returned in ``f`` are those for which
the product gives ``g``: ``g = f[n]*...f[1]*f[0]`` where ``n = len(B)``
and ``B = G.base``. f[i] is one of the permutations in
``self._basic_orbits[i]``.
If factor_index==True,
returns a tuple ``[b[0],..,b[n]]``, where ``b[i]``
belongs to ``self._basic_orbits[i]``
Examples
========
>>> from sympy.combinatorics import Permutation, PermutationGroup
>>> Permutation.print_cyclic = True
>>> a = Permutation(0, 1, 3, 7, 6, 4)(2, 5)
>>> b = Permutation(0, 1, 3, 2)(4, 5, 7, 6)
>>> G = PermutationGroup([a, b])
Define g:
>>> g = Permutation(7)(1, 2, 4)(3, 6, 5)
Confirm that it is an element of G:
>>> G.contains(g)
True
Thus, it can be written as a product of factors (up to
3) drawn from u. See below that a factor from u1 and u2
and the Identity permutation have been used:
>>> f = G.coset_factor(g)
>>> f[2]*f[1]*f[0] == g
True
>>> f1 = G.coset_factor(g, True); f1
[0, 4, 4]
>>> tr = G.basic_transversals
>>> f[0] == tr[0][f1[0]]
True
If g is not an element of G then [] is returned:
>>> c = Permutation(5, 6, 7)
>>> G.coset_factor(c)
[]
See Also
========
util._strip
"""
if isinstance(g, (Cycle, Permutation)):
g = g.list()
if len(g) != self._degree:
# this could either adjust the size or return [] immediately
# but we don't choose between the two and just signal a possible
# error
raise ValueError('g should be the same size as permutations of G')
I = list(range(self._degree))
basic_orbits = self.basic_orbits
transversals = self._transversals
factors = []
base = self.base
h = g
for i in range(len(base)):
beta = h[base[i]]
if beta == base[i]:
factors.append(beta)
continue
if beta not in basic_orbits[i]:
return []
u = transversals[i][beta]._array_form
h = _af_rmul(_af_invert(u), h)
factors.append(beta)
if h != I:
return []
if factor_index:
return factors
tr = self.basic_transversals
factors = [tr[i][factors[i]] for i in range(len(base))]
return factors
def generator_product(self, g, original=False):
'''
Return a list of strong generators `[s1, ..., sn]`
s.t `g = sn*...*s1`. If `original=True`, make the list
contain only the original group generators
'''
product = []
if g.is_identity:
return []
if g in self.strong_gens:
if not original or g in self.generators:
return [g]
else:
slp = self._strong_gens_slp[g]
for s in slp:
product.extend(self.generator_product(s, original=True))
return product
elif g**-1 in self.strong_gens:
g = g**-1
if not original or g in self.generators:
return [g**-1]
else:
slp = self._strong_gens_slp[g]
for s in slp:
product.extend(self.generator_product(s, original=True))
l = len(product)
product = [product[l-i-1]**-1 for i in range(l)]
return product
f = self.coset_factor(g, True)
for i, j in enumerate(f):
slp = self._transversal_slp[i][j]
for s in slp:
if not original:
product.append(self.strong_gens[s])
else:
s = self.strong_gens[s]
product.extend(self.generator_product(s, original=True))
return product
def coset_rank(self, g):
"""rank using Schreier-Sims representation
The coset rank of ``g`` is the ordering number in which
it appears in the lexicographic listing according to the
coset decomposition
The ordering is the same as in G.generate(method='coset').
If ``g`` does not belong to the group it returns None.
Examples
========
>>> from sympy.combinatorics import Permutation
>>> Permutation.print_cyclic = True
>>> from sympy.combinatorics.perm_groups import PermutationGroup
>>> a = Permutation(0, 1, 3, 7, 6, 4)(2, 5)
>>> b = Permutation(0, 1, 3, 2)(4, 5, 7, 6)
>>> G = PermutationGroup([a, b])
>>> c = Permutation(7)(2, 4)(3, 5)
>>> G.coset_rank(c)
16
>>> G.coset_unrank(16)
(7)(2 4)(3 5)
See Also
========
coset_factor
"""
factors = self.coset_factor(g, True)
if not factors:
return None
rank = 0
b = 1
transversals = self._transversals
base = self._base
basic_orbits = self._basic_orbits
for i in range(len(base)):
k = factors[i]
j = basic_orbits[i].index(k)
rank += b*j
b = b*len(transversals[i])
return rank
def coset_unrank(self, rank, af=False):
"""unrank using Schreier-Sims representation
coset_unrank is the inverse operation of coset_rank
if 0 <= rank < order; otherwise it returns None.
"""
if rank < 0 or rank >= self.order():
return None
base = self.base
transversals = self.basic_transversals
basic_orbits = self.basic_orbits
m = len(base)
v = [0]*m
for i in range(m):
rank, c = divmod(rank, len(transversals[i]))
v[i] = basic_orbits[i][c]
a = [transversals[i][v[i]]._array_form for i in range(m)]
h = _af_rmuln(*a)
if af:
return h
else:
return _af_new(h)
@property
def degree(self):
"""Returns the size of the permutations in the group.
The number of permutations comprising the group is given by
``len(group)``; the number of permutations that can be generated
by the group is given by ``group.order()``.
Examples
========
>>> from sympy.combinatorics import Permutation
>>> Permutation.print_cyclic = True
>>> from sympy.combinatorics.perm_groups import PermutationGroup
>>> a = Permutation([1, 0, 2])
>>> G = PermutationGroup([a])
>>> G.degree
3
>>> len(G)
1
>>> G.order()
2
>>> list(G.generate())
[(2), (2)(0 1)]
See Also
========
order
"""
return self._degree
@property
def identity(self):
'''
Return the identity element of the permutation group.
'''
return _af_new(list(range(self.degree)))
@property
def elements(self):
"""Returns all the elements of the permutation group as a set
Examples
========
>>> from sympy.combinatorics import Permutation, PermutationGroup
>>> p = PermutationGroup(Permutation(1, 3), Permutation(1, 2))
>>> p.elements
{(3), (2 3), (3)(1 2), (1 2 3), (1 3 2), (1 3)}
"""
return set(self._elements)
@property
def _elements(self):
"""Returns all the elements of the permutation group as a list
Examples
========
>>> from sympy.combinatorics import Permutation, PermutationGroup
>>> p = PermutationGroup(Permutation(1, 3), Permutation(1, 2))
>>> p._elements
[(3), (3)(1 2), (1 3), (2 3), (1 2 3), (1 3 2)]
"""
return list(islice(self.generate(), None))
def derived_series(self):
r"""Return the derived series for the group.
The derived series for a group `G` is defined as
`G = G_0 > G_1 > G_2 > \ldots` where `G_i = [G_{i-1}, G_{i-1}]`,
i.e. `G_i` is the derived subgroup of `G_{i-1}`, for
`i\in\mathbb{N}`. When we have `G_k = G_{k-1}` for some
`k\in\mathbb{N}`, the series terminates.
Returns
=======
A list of permutation groups containing the members of the derived
series in the order `G = G_0, G_1, G_2, \ldots`.
Examples
========
>>> from sympy.combinatorics.named_groups import (SymmetricGroup,
... AlternatingGroup, DihedralGroup)
>>> A = AlternatingGroup(5)
>>> len(A.derived_series())
1
>>> S = SymmetricGroup(4)
>>> len(S.derived_series())
4
>>> S.derived_series()[1].is_subgroup(AlternatingGroup(4))
True
>>> S.derived_series()[2].is_subgroup(DihedralGroup(2))
True
See Also
========
derived_subgroup
"""
res = [self]
current = self
next = self.derived_subgroup()
while not current.is_subgroup(next):
res.append(next)
current = next
next = next.derived_subgroup()
return res
def derived_subgroup(self):
r"""Compute the derived subgroup.
The derived subgroup, or commutator subgroup is the subgroup generated
by all commutators `[g, h] = hgh^{-1}g^{-1}` for `g, h\in G` ; it is
equal to the normal closure of the set of commutators of the generators
([1], p.28, [11]).
Examples
========
>>> from sympy.combinatorics import Permutation
>>> Permutation.print_cyclic = True
>>> from sympy.combinatorics.perm_groups import PermutationGroup
>>> a = Permutation([1, 0, 2, 4, 3])
>>> b = Permutation([0, 1, 3, 2, 4])
>>> G = PermutationGroup([a, b])
>>> C = G.derived_subgroup()
>>> list(C.generate(af=True))
[[0, 1, 2, 3, 4], [0, 1, 3, 4, 2], [0, 1, 4, 2, 3]]
See Also
========
derived_series
"""
r = self._r
gens = [p._array_form for p in self.generators]
set_commutators = set()
degree = self._degree
rng = list(range(degree))
for i in range(r):
for j in range(r):
p1 = gens[i]
p2 = gens[j]
c = list(range(degree))
for k in rng:
c[p2[p1[k]]] = p1[p2[k]]
ct = tuple(c)
if not ct in set_commutators:
set_commutators.add(ct)
cms = [_af_new(p) for p in set_commutators]
G2 = self.normal_closure(cms)
return G2
def generate(self, method="coset", af=False):
"""Return iterator to generate the elements of the group
Iteration is done with one of these methods::
method='coset' using the Schreier-Sims coset representation
method='dimino' using the Dimino method
If af = True it yields the array form of the permutations
Examples
========
>>> from sympy.combinatorics import Permutation
>>> Permutation.print_cyclic = True
>>> from sympy.combinatorics import PermutationGroup
>>> from sympy.combinatorics.polyhedron import tetrahedron
The permutation group given in the tetrahedron object is also
true groups:
>>> G = tetrahedron.pgroup
>>> G.is_group
True
Also the group generated by the permutations in the tetrahedron
pgroup -- even the first two -- is a proper group:
>>> H = PermutationGroup(G[0], G[1])
>>> J = PermutationGroup(list(H.generate())); J
PermutationGroup([
(0 1)(2 3),
(1 2 3),
(1 3 2),
(0 3 1),
(0 2 3),
(0 3)(1 2),
(0 1 3),
(3)(0 2 1),
(0 3 2),
(3)(0 1 2),
(0 2)(1 3)])
>>> _.is_group
True
"""
if method == "coset":
return self.generate_schreier_sims(af)
elif method == "dimino":
return self.generate_dimino(af)
else:
raise NotImplementedError('No generation defined for %s' % method)
def generate_dimino(self, af=False):
"""Yield group elements using Dimino's algorithm
If af == True it yields the array form of the permutations
Examples
========
>>> from sympy.combinatorics import Permutation
>>> Permutation.print_cyclic = True
>>> from sympy.combinatorics.perm_groups import PermutationGroup
>>> a = Permutation([0, 2, 1, 3])
>>> b = Permutation([0, 2, 3, 1])
>>> g = PermutationGroup([a, b])
>>> list(g.generate_dimino(af=True))
[[0, 1, 2, 3], [0, 2, 1, 3], [0, 2, 3, 1],
[0, 1, 3, 2], [0, 3, 2, 1], [0, 3, 1, 2]]
References
==========
.. [1] The Implementation of Various Algorithms for Permutation Groups in
the Computer Algebra System: AXIOM, N.J. Doye, M.Sc. Thesis
"""
idn = list(range(self.degree))
order = 0
element_list = [idn]
set_element_list = {tuple(idn)}
if af:
yield idn
else:
yield _af_new(idn)
gens = [p._array_form for p in self.generators]
for i in range(len(gens)):
# D elements of the subgroup G_i generated by gens[:i]
D = element_list[:]
N = [idn]
while N:
A = N
N = []
for a in A:
for g in gens[:i + 1]:
ag = _af_rmul(a, g)
if tuple(ag) not in set_element_list:
# produce G_i*g
for d in D:
order += 1
ap = _af_rmul(d, ag)
if af:
yield ap
else:
p = _af_new(ap)
yield p
element_list.append(ap)
set_element_list.add(tuple(ap))
N.append(ap)
self._order = len(element_list)
def generate_schreier_sims(self, af=False):
"""Yield group elements using the Schreier-Sims representation
in coset_rank order
If ``af = True`` it yields the array form of the permutations
Examples
========
>>> from sympy.combinatorics import Permutation
>>> Permutation.print_cyclic = True
>>> from sympy.combinatorics.perm_groups import PermutationGroup
>>> a = Permutation([0, 2, 1, 3])
>>> b = Permutation([0, 2, 3, 1])
>>> g = PermutationGroup([a, b])
>>> list(g.generate_schreier_sims(af=True))
[[0, 1, 2, 3], [0, 2, 1, 3], [0, 3, 2, 1],
[0, 1, 3, 2], [0, 2, 3, 1], [0, 3, 1, 2]]
"""
n = self._degree
u = self.basic_transversals
basic_orbits = self._basic_orbits
if len(u) == 0:
for x in self.generators:
if af:
yield x._array_form
else:
yield x
return
if len(u) == 1:
for i in basic_orbits[0]:
if af:
yield u[0][i]._array_form
else:
yield u[0][i]
return
u = list(reversed(u))
basic_orbits = basic_orbits[::-1]
# stg stack of group elements
stg = [list(range(n))]
posmax = [len(x) for x in u]
n1 = len(posmax) - 1
pos = [0]*n1
h = 0
while 1:
# backtrack when finished iterating over coset
if pos[h] >= posmax[h]:
if h == 0:
return
pos[h] = 0
h -= 1
stg.pop()
continue
p = _af_rmul(u[h][basic_orbits[h][pos[h]]]._array_form, stg[-1])
pos[h] += 1
stg.append(p)
h += 1
if h == n1:
if af:
for i in basic_orbits[-1]:
p = _af_rmul(u[-1][i]._array_form, stg[-1])
yield p
else:
for i in basic_orbits[-1]:
p = _af_rmul(u[-1][i]._array_form, stg[-1])
p1 = _af_new(p)
yield p1
stg.pop()
h -= 1
@property
def generators(self):
"""Returns the generators of the group.
Examples
========
>>> from sympy.combinatorics import Permutation
>>> Permutation.print_cyclic = True
>>> from sympy.combinatorics.perm_groups import PermutationGroup
>>> a = Permutation([0, 2, 1])
>>> b = Permutation([1, 0, 2])
>>> G = PermutationGroup([a, b])
>>> G.generators
[(1 2), (2)(0 1)]
"""
return self._generators
def contains(self, g, strict=True):
"""Test if permutation ``g`` belong to self, ``G``.
If ``g`` is an element of ``G`` it can be written as a product
of factors drawn from the cosets of ``G``'s stabilizers. To see
if ``g`` is one of the actual generators defining the group use
``G.has(g)``.
If ``strict`` is not ``True``, ``g`` will be resized, if necessary,
to match the size of permutations in ``self``.
Examples
========
>>> from sympy.combinatorics import Permutation
>>> Permutation.print_cyclic = True
>>> from sympy.combinatorics.perm_groups import PermutationGroup
>>> a = Permutation(1, 2)
>>> b = Permutation(2, 3, 1)
>>> G = PermutationGroup(a, b, degree=5)
>>> G.contains(G[0]) # trivial check
True
>>> elem = Permutation([[2, 3]], size=5)
>>> G.contains(elem)
True
>>> G.contains(Permutation(4)(0, 1, 2, 3))
False
If strict is False, a permutation will be resized, if
necessary:
>>> H = PermutationGroup(Permutation(5))
>>> H.contains(Permutation(3))
False
>>> H.contains(Permutation(3), strict=False)
True
To test if a given permutation is present in the group:
>>> elem in G.generators
False
>>> G.has(elem)
False
See Also
========
coset_factor, has, in
"""
if not isinstance(g, Permutation):
return False
if g.size != self.degree:
if strict:
return False
g = Permutation(g, size=self.degree)
if g in self.generators:
return True
return bool(self.coset_factor(g.array_form, True))
@property
def is_abelian(self):
"""Test if the group is Abelian.
Examples
========
>>> from sympy.combinatorics import Permutation
>>> Permutation.print_cyclic = True
>>> from sympy.combinatorics.perm_groups import PermutationGroup
>>> a = Permutation([0, 2, 1])
>>> b = Permutation([1, 0, 2])
>>> G = PermutationGroup([a, b])
>>> G.is_abelian
False
>>> a = Permutation([0, 2, 1])
>>> G = PermutationGroup([a])
>>> G.is_abelian
True
"""
if self._is_abelian is not None:
return self._is_abelian
self._is_abelian = True
gens = [p._array_form for p in self.generators]
for x in gens:
for y in gens:
if y <= x:
continue
if not _af_commutes_with(x, y):
self._is_abelian = False
return False
return True
def is_alt_sym(self, eps=0.05, _random_prec=None):
r"""Monte Carlo test for the symmetric/alternating group for degrees
>= 8.
More specifically, it is one-sided Monte Carlo with the
answer True (i.e., G is symmetric/alternating) guaranteed to be
correct, and the answer False being incorrect with probability eps.
For degree < 8, the order of the group is checked so the test
is deterministic.
Notes
=====
The algorithm itself uses some nontrivial results from group theory and
number theory:
1) If a transitive group ``G`` of degree ``n`` contains an element
with a cycle of length ``n/2 < p < n-2`` for ``p`` a prime, ``G`` is the
symmetric or alternating group ([1], pp. 81-82)
2) The proportion of elements in the symmetric/alternating group having
the property described in 1) is approximately `\log(2)/\log(n)`
([1], p.82; [2], pp. 226-227).
The helper function ``_check_cycles_alt_sym`` is used to
go over the cycles in a permutation and look for ones satisfying 1).
Examples
========
>>> from sympy.combinatorics.perm_groups import PermutationGroup
>>> from sympy.combinatorics.named_groups import DihedralGroup
>>> D = DihedralGroup(10)
>>> D.is_alt_sym()
False
See Also
========
_check_cycles_alt_sym
"""
if _random_prec is None:
if self._is_sym or self._is_alt:
return True
n = self.degree
if n < 8:
sym_order = 1
for i in range(2, n+1):
sym_order *= i
order = self.order()
if order == sym_order:
self._is_sym = True
return True
elif 2*order == sym_order:
self._is_alt = True
return True
return False
if not self.is_transitive():
return False
if n < 17:
c_n = 0.34
else:
c_n = 0.57
d_n = (c_n*log(2))/log(n)
N_eps = int(-log(eps)/d_n)
for i in range(N_eps):
perm = self.random_pr()
if _check_cycles_alt_sym(perm):
return True
return False
else:
for i in range(_random_prec['N_eps']):
perm = _random_prec[i]
if _check_cycles_alt_sym(perm):
return True
return False
@property
def is_nilpotent(self):
"""Test if the group is nilpotent.
A group `G` is nilpotent if it has a central series of finite length.
Alternatively, `G` is nilpotent if its lower central series terminates
with the trivial group. Every nilpotent group is also solvable
([1], p.29, [12]).
Examples
========
>>> from sympy.combinatorics.named_groups import (SymmetricGroup,
... CyclicGroup)
>>> C = CyclicGroup(6)
>>> C.is_nilpotent
True
>>> S = SymmetricGroup(5)
>>> S.is_nilpotent
False
See Also
========
lower_central_series, is_solvable
"""
if self._is_nilpotent is None:
lcs = self.lower_central_series()
terminator = lcs[len(lcs) - 1]
gens = terminator.generators
degree = self.degree
identity = _af_new(list(range(degree)))
if all(g == identity for g in gens):
self._is_solvable = True
self._is_nilpotent = True
return True
else:
self._is_nilpotent = False
return False
else:
return self._is_nilpotent
def is_normal(self, gr, strict=True):
"""Test if ``G=self`` is a normal subgroup of ``gr``.
G is normal in gr if
for each g2 in G, g1 in gr, ``g = g1*g2*g1**-1`` belongs to G
It is sufficient to check this for each g1 in gr.generators and
g2 in G.generators.
Examples
========
>>> from sympy.combinatorics import Permutation
>>> Permutation.print_cyclic = True
>>> from sympy.combinatorics.perm_groups import PermutationGroup
>>> a = Permutation([1, 2, 0])
>>> b = Permutation([1, 0, 2])
>>> G = PermutationGroup([a, b])
>>> G1 = PermutationGroup([a, Permutation([2, 0, 1])])
>>> G1.is_normal(G)
True
"""
if not self.is_subgroup(gr, strict=strict):
return False
d_self = self.degree
d_gr = gr.degree
if self.is_trivial and (d_self == d_gr or not strict):
return True
new_self = self.copy()
if not strict and d_self != d_gr:
if d_self < d_gr:
new_self = PermGroup(new_self.generators + [Permutation(d_gr - 1)])
else:
gr = PermGroup(gr.generators + [Permutation(d_self - 1)])
gens2 = [p._array_form for p in new_self.generators]
gens1 = [p._array_form for p in gr.generators]
for g1 in gens1:
for g2 in gens2:
p = _af_rmuln(g1, g2, _af_invert(g1))
if not new_self.coset_factor(p, True):
return False
return True
def is_primitive(self, randomized=True):
r"""Test if a group is primitive.
A permutation group ``G`` acting on a set ``S`` is called primitive if
``S`` contains no nontrivial block under the action of ``G``
(a block is nontrivial if its cardinality is more than ``1``).
Notes
=====
The algorithm is described in [1], p.83, and uses the function
minimal_block to search for blocks of the form `\{0, k\}` for ``k``
ranging over representatives for the orbits of `G_0`, the stabilizer of
``0``. This algorithm has complexity `O(n^2)` where ``n`` is the degree
of the group, and will perform badly if `G_0` is small.
There are two implementations offered: one finds `G_0`
deterministically using the function ``stabilizer``, and the other
(default) produces random elements of `G_0` using ``random_stab``,
hoping that they generate a subgroup of `G_0` with not too many more
orbits than `G_0` (this is suggested in [1], p.83). Behavior is changed
by the ``randomized`` flag.
Examples
========
>>> from sympy.combinatorics.perm_groups import PermutationGroup
>>> from sympy.combinatorics.named_groups import DihedralGroup
>>> D = DihedralGroup(10)
>>> D.is_primitive()
False
See Also
========
minimal_block, random_stab
"""
if self._is_primitive is not None:
return self._is_primitive
if randomized:
random_stab_gens = []
v = self.schreier_vector(0)
for i in range(len(self)):
random_stab_gens.append(self.random_stab(0, v))
stab = PermutationGroup(random_stab_gens)
else:
stab = self.stabilizer(0)
orbits = stab.orbits()
for orb in orbits:
x = orb.pop()
if x != 0 and any(e != 0 for e in self.minimal_block([0, x])):
self._is_primitive = False
return False
self._is_primitive = True
return True
def minimal_blocks(self, randomized=True):
'''
For a transitive group, return the list of all minimal
block systems. If a group is intransitive, return `False`.
Examples
========
>>> from sympy.combinatorics import Permutation
>>> from sympy.combinatorics.perm_groups import PermutationGroup
>>> from sympy.combinatorics.named_groups import DihedralGroup
>>> DihedralGroup(6).minimal_blocks()
[[0, 1, 0, 1, 0, 1], [0, 1, 2, 0, 1, 2]]
>>> G = PermutationGroup(Permutation(1,2,5))
>>> G.minimal_blocks()
False
See Also
========
minimal_block, is_transitive, is_primitive
'''
def _number_blocks(blocks):
# number the blocks of a block system
# in order and return the number of
# blocks and the tuple with the
# reordering
n = len(blocks)
appeared = {}
m = 0
b = [None]*n
for i in range(n):
if blocks[i] not in appeared:
appeared[blocks[i]] = m
b[i] = m
m += 1
else:
b[i] = appeared[blocks[i]]
return tuple(b), m
if not self.is_transitive():
return False
blocks = []
num_blocks = []
rep_blocks = []
if randomized:
random_stab_gens = []
v = self.schreier_vector(0)
for i in range(len(self)):
random_stab_gens.append(self.random_stab(0, v))
stab = PermutationGroup(random_stab_gens)
else:
stab = self.stabilizer(0)
orbits = stab.orbits()
for orb in orbits:
x = orb.pop()
if x != 0:
block = self.minimal_block([0, x])
num_block, m = _number_blocks(block)
# a representative block (containing 0)
rep = set(j for j in range(self.degree) if num_block[j] == 0)
# check if the system is minimal with
# respect to the already discovere ones
minimal = True
to_remove = []
for i, r in enumerate(rep_blocks):
if len(r) > len(rep) and rep.issubset(r):
# i-th block system is not minimal
del num_blocks[i], blocks[i]
to_remove.append(rep_blocks[i])
elif len(r) < len(rep) and r.issubset(rep):
# the system being checked is not minimal
minimal = False
break
# remove non-minimal representative blocks
rep_blocks = [r for r in rep_blocks if r not in to_remove]
if minimal and num_block not in num_blocks:
blocks.append(block)
num_blocks.append(num_block)
rep_blocks.append(rep)
return blocks
@property
def is_solvable(self):
"""Test if the group is solvable.
``G`` is solvable if its derived series terminates with the trivial
group ([1], p.29).
Examples
========
>>> from sympy.combinatorics.named_groups import SymmetricGroup
>>> S = SymmetricGroup(3)
>>> S.is_solvable
True
See Also
========
is_nilpotent, derived_series
"""
if self._is_solvable is None:
ds = self.derived_series()
terminator = ds[len(ds) - 1]
gens = terminator.generators
degree = self.degree
identity = _af_new(list(range(degree)))
if all(g == identity for g in gens):
self._is_solvable = True
return True
else:
self._is_solvable = False
return False
else:
return self._is_solvable
def is_subgroup(self, G, strict=True):
"""Return ``True`` if all elements of ``self`` belong to ``G``.
If ``strict`` is ``False`` then if ``self``'s degree is smaller
than ``G``'s, the elements will be resized to have the same degree.
Examples
========
>>> from sympy.combinatorics import Permutation, PermutationGroup
>>> from sympy.combinatorics.named_groups import (SymmetricGroup,
... CyclicGroup)
Testing is strict by default: the degree of each group must be the
same:
>>> p = Permutation(0, 1, 2, 3, 4, 5)
>>> G1 = PermutationGroup([Permutation(0, 1, 2), Permutation(0, 1)])
>>> G2 = PermutationGroup([Permutation(0, 2), Permutation(0, 1, 2)])
>>> G3 = PermutationGroup([p, p**2])
>>> assert G1.order() == G2.order() == G3.order() == 6
>>> G1.is_subgroup(G2)
True
>>> G1.is_subgroup(G3)
False
>>> G3.is_subgroup(PermutationGroup(G3[1]))
False
>>> G3.is_subgroup(PermutationGroup(G3[0]))
True
To ignore the size, set ``strict`` to ``False``:
>>> S3 = SymmetricGroup(3)
>>> S5 = SymmetricGroup(5)
>>> S3.is_subgroup(S5, strict=False)
True
>>> C7 = CyclicGroup(7)
>>> G = S5*C7
>>> S5.is_subgroup(G, False)
True
>>> C7.is_subgroup(G, 0)
False
"""
if not isinstance(G, PermutationGroup):
return False
if self == G or self.generators[0]==Permutation():
return True
if G.order() % self.order() != 0:
return False
if self.degree == G.degree or \
(self.degree < G.degree and not strict):
gens = self.generators
else:
return False
return all(G.contains(g, strict=strict) for g in gens)
def is_transitive(self, strict=True):
"""Test if the group is transitive.
A group is transitive if it has a single orbit.
If ``strict`` is ``False`` the group is transitive if it has
a single orbit of length different from 1.
Examples
========
>>> from sympy.combinatorics.permutations import Permutation
>>> from sympy.combinatorics.perm_groups import PermutationGroup
>>> a = Permutation([0, 2, 1, 3])
>>> b = Permutation([2, 0, 1, 3])
>>> G1 = PermutationGroup([a, b])
>>> G1.is_transitive()
False
>>> G1.is_transitive(strict=False)
True
>>> c = Permutation([2, 3, 0, 1])
>>> G2 = PermutationGroup([a, c])
>>> G2.is_transitive()
True
>>> d = Permutation([1, 0, 2, 3])
>>> e = Permutation([0, 1, 3, 2])
>>> G3 = PermutationGroup([d, e])
>>> G3.is_transitive() or G3.is_transitive(strict=False)
False
"""
if self._is_transitive: # strict or not, if True then True
return self._is_transitive
if strict:
if self._is_transitive is not None: # we only store strict=True
return self._is_transitive
ans = len(self.orbit(0)) == self.degree
self._is_transitive = ans
return ans
got_orb = False
for x in self.orbits():
if len(x) > 1:
if got_orb:
return False
got_orb = True
return got_orb
@property
def is_trivial(self):
"""Test if the group is the trivial group.
This is true if the group contains only the identity permutation.
Examples
========
>>> from sympy.combinatorics import Permutation
>>> from sympy.combinatorics.perm_groups import PermutationGroup
>>> G = PermutationGroup([Permutation([0, 1, 2])])
>>> G.is_trivial
True
"""
if self._is_trivial is None:
self._is_trivial = len(self) == 1 and self[0].is_Identity
return self._is_trivial
def lower_central_series(self):
r"""Return the lower central series for the group.
The lower central series for a group `G` is the series
`G = G_0 > G_1 > G_2 > \ldots` where
`G_k = [G, G_{k-1}]`, i.e. every term after the first is equal to the
commutator of `G` and the previous term in `G1` ([1], p.29).
Returns
=======
A list of permutation groups in the order `G = G_0, G_1, G_2, \ldots`
Examples
========
>>> from sympy.combinatorics.named_groups import (AlternatingGroup,
... DihedralGroup)
>>> A = AlternatingGroup(4)
>>> len(A.lower_central_series())
2
>>> A.lower_central_series()[1].is_subgroup(DihedralGroup(2))
True
See Also
========
commutator, derived_series
"""
res = [self]
current = self
next = self.commutator(self, current)
while not current.is_subgroup(next):
res.append(next)
current = next
next = self.commutator(self, current)
return res
@property
def max_div(self):
"""Maximum proper divisor of the degree of a permutation group.
Notes
=====
Obviously, this is the degree divided by its minimal proper divisor
(larger than ``1``, if one exists). As it is guaranteed to be prime,
the ``sieve`` from ``sympy.ntheory`` is used.
This function is also used as an optimization tool for the functions
``minimal_block`` and ``_union_find_merge``.
Examples
========
>>> from sympy.combinatorics import Permutation
>>> from sympy.combinatorics.perm_groups import PermutationGroup
>>> G = PermutationGroup([Permutation([0, 2, 1, 3])])
>>> G.max_div
2
See Also
========
minimal_block, _union_find_merge
"""
if self._max_div is not None:
return self._max_div
n = self.degree
if n == 1:
return 1
for x in sieve:
if n % x == 0:
d = n//x
self._max_div = d
return d
def minimal_block(self, points):
r"""For a transitive group, finds the block system generated by
``points``.
If a group ``G`` acts on a set ``S``, a nonempty subset ``B`` of ``S``
is called a block under the action of ``G`` if for all ``g`` in ``G``
we have ``gB = B`` (``g`` fixes ``B``) or ``gB`` and ``B`` have no
common points (``g`` moves ``B`` entirely). ([1], p.23; [6]).
The distinct translates ``gB`` of a block ``B`` for ``g`` in ``G``
partition the set ``S`` and this set of translates is known as a block
system. Moreover, we obviously have that all blocks in the partition
have the same size, hence the block size divides ``|S|`` ([1], p.23).
A ``G``-congruence is an equivalence relation ``~`` on the set ``S``
such that ``a ~ b`` implies ``g(a) ~ g(b)`` for all ``g`` in ``G``.
For a transitive group, the equivalence classes of a ``G``-congruence
and the blocks of a block system are the same thing ([1], p.23).
The algorithm below checks the group for transitivity, and then finds
the ``G``-congruence generated by the pairs ``(p_0, p_1), (p_0, p_2),
..., (p_0,p_{k-1})`` which is the same as finding the maximal block
system (i.e., the one with minimum block size) such that
``p_0, ..., p_{k-1}`` are in the same block ([1], p.83).
It is an implementation of Atkinson's algorithm, as suggested in [1],
and manipulates an equivalence relation on the set ``S`` using a
union-find data structure. The running time is just above
`O(|points||S|)`. ([1], pp. 83-87; [7]).
Examples
========
>>> from sympy.combinatorics.perm_groups import PermutationGroup
>>> from sympy.combinatorics.named_groups import DihedralGroup
>>> D = DihedralGroup(10)
>>> D.minimal_block([0, 5])
[0, 1, 2, 3, 4, 0, 1, 2, 3, 4]
>>> D.minimal_block([0, 1])
[0, 0, 0, 0, 0, 0, 0, 0, 0, 0]
See Also
========
_union_find_rep, _union_find_merge, is_transitive, is_primitive
"""
if not self.is_transitive():
return False
n = self.degree
gens = self.generators
# initialize the list of equivalence class representatives
parents = list(range(n))
ranks = [1]*n
not_rep = []
k = len(points)
# the block size must divide the degree of the group
if k > self.max_div:
return [0]*n
for i in range(k - 1):
parents[points[i + 1]] = points[0]
not_rep.append(points[i + 1])
ranks[points[0]] = k
i = 0
len_not_rep = k - 1
while i < len_not_rep:
gamma = not_rep[i]
i += 1
for gen in gens:
# find has side effects: performs path compression on the list
# of representatives
delta = self._union_find_rep(gamma, parents)
# union has side effects: performs union by rank on the list
# of representatives
temp = self._union_find_merge(gen(gamma), gen(delta), ranks,
parents, not_rep)
if temp == -1:
return [0]*n
len_not_rep += temp
for i in range(n):
# force path compression to get the final state of the equivalence
# relation
self._union_find_rep(i, parents)
# rewrite result so that block representatives are minimal
new_reps = {}
return [new_reps.setdefault(r, i) for i, r in enumerate(parents)]
def normal_closure(self, other, k=10):
r"""Return the normal closure of a subgroup/set of permutations.
If ``S`` is a subset of a group ``G``, the normal closure of ``A`` in ``G``
is defined as the intersection of all normal subgroups of ``G`` that
contain ``A`` ([1], p.14). Alternatively, it is the group generated by
the conjugates ``x^{-1}yx`` for ``x`` a generator of ``G`` and ``y`` a
generator of the subgroup ``\left\langle S\right\rangle`` generated by
``S`` (for some chosen generating set for ``\left\langle S\right\rangle``)
([1], p.73).
Parameters
==========
other
a subgroup/list of permutations/single permutation
k
an implementation-specific parameter that determines the number
of conjugates that are adjoined to ``other`` at once
Examples
========
>>> from sympy.combinatorics.named_groups import (SymmetricGroup,
... CyclicGroup, AlternatingGroup)
>>> S = SymmetricGroup(5)
>>> C = CyclicGroup(5)
>>> G = S.normal_closure(C)
>>> G.order()
60
>>> G.is_subgroup(AlternatingGroup(5))
True
See Also
========
commutator, derived_subgroup, random_pr
Notes
=====
The algorithm is described in [1], pp. 73-74; it makes use of the
generation of random elements for permutation groups by the product
replacement algorithm.
"""
if hasattr(other, 'generators'):
degree = self.degree
identity = _af_new(list(range(degree)))
if all(g == identity for g in other.generators):
return other
Z = PermutationGroup(other.generators[:])
base, strong_gens = Z.schreier_sims_incremental()
strong_gens_distr = _distribute_gens_by_base(base, strong_gens)
basic_orbits, basic_transversals = \
_orbits_transversals_from_bsgs(base, strong_gens_distr)
self._random_pr_init(r=10, n=20)
_loop = True
while _loop:
Z._random_pr_init(r=10, n=10)
for i in range(k):
g = self.random_pr()
h = Z.random_pr()
conj = h^g
res = _strip(conj, base, basic_orbits, basic_transversals)
if res[0] != identity or res[1] != len(base) + 1:
gens = Z.generators
gens.append(conj)
Z = PermutationGroup(gens)
strong_gens.append(conj)
temp_base, temp_strong_gens = \
Z.schreier_sims_incremental(base, strong_gens)
base, strong_gens = temp_base, temp_strong_gens
strong_gens_distr = \
_distribute_gens_by_base(base, strong_gens)
basic_orbits, basic_transversals = \
_orbits_transversals_from_bsgs(base,
strong_gens_distr)
_loop = False
for g in self.generators:
for h in Z.generators:
conj = h^g
res = _strip(conj, base, basic_orbits,
basic_transversals)
if res[0] != identity or res[1] != len(base) + 1:
_loop = True
break
if _loop:
break
return Z
elif hasattr(other, '__getitem__'):
return self.normal_closure(PermutationGroup(other))
elif hasattr(other, 'array_form'):
return self.normal_closure(PermutationGroup([other]))
def orbit(self, alpha, action='tuples'):
r"""Compute the orbit of alpha `\{g(\alpha) | g \in G\}` as a set.
The time complexity of the algorithm used here is `O(|Orb|*r)` where
`|Orb|` is the size of the orbit and ``r`` is the number of generators of
the group. For a more detailed analysis, see [1], p.78, [2], pp. 19-21.
Here alpha can be a single point, or a list of points.
If alpha is a single point, the ordinary orbit is computed.
if alpha is a list of points, there are three available options:
'union' - computes the union of the orbits of the points in the list
'tuples' - computes the orbit of the list interpreted as an ordered
tuple under the group action ( i.e., g((1,2,3)) = (g(1), g(2), g(3)) )
'sets' - computes the orbit of the list interpreted as a sets
Examples
========
>>> from sympy.combinatorics import Permutation
>>> from sympy.combinatorics.perm_groups import PermutationGroup
>>> a = Permutation([1, 2, 0, 4, 5, 6, 3])
>>> G = PermutationGroup([a])
>>> G.orbit(0)
{0, 1, 2}
>>> G.orbit([0, 4], 'union')
{0, 1, 2, 3, 4, 5, 6}
See Also
========
orbit_transversal
"""
return _orbit(self.degree, self.generators, alpha, action)
def orbit_rep(self, alpha, beta, schreier_vector=None):
"""Return a group element which sends ``alpha`` to ``beta``.
If ``beta`` is not in the orbit of ``alpha``, the function returns
``False``. This implementation makes use of the schreier vector.
For a proof of correctness, see [1], p.80
Examples
========
>>> from sympy.combinatorics import Permutation
>>> Permutation.print_cyclic = True
>>> from sympy.combinatorics.perm_groups import PermutationGroup
>>> from sympy.combinatorics.named_groups import AlternatingGroup
>>> G = AlternatingGroup(5)
>>> G.orbit_rep(0, 4)
(0 4 1 2 3)
See Also
========
schreier_vector
"""
if schreier_vector is None:
schreier_vector = self.schreier_vector(alpha)
if schreier_vector[beta] is None:
return False
k = schreier_vector[beta]
gens = [x._array_form for x in self.generators]
a = []
while k != -1:
a.append(gens[k])
beta = gens[k].index(beta) # beta = (~gens[k])(beta)
k = schreier_vector[beta]
if a:
return _af_new(_af_rmuln(*a))
else:
return _af_new(list(range(self._degree)))
def orbit_transversal(self, alpha, pairs=False):
r"""Computes a transversal for the orbit of ``alpha`` as a set.
For a permutation group `G`, a transversal for the orbit
`Orb = \{g(\alpha) | g \in G\}` is a set
`\{g_\beta | g_\beta(\alpha) = \beta\}` for `\beta \in Orb`.
Note that there may be more than one possible transversal.
If ``pairs`` is set to ``True``, it returns the list of pairs
`(\beta, g_\beta)`. For a proof of correctness, see [1], p.79
Examples
========
>>> from sympy.combinatorics import Permutation
>>> Permutation.print_cyclic = True
>>> from sympy.combinatorics.perm_groups import PermutationGroup
>>> from sympy.combinatorics.named_groups import DihedralGroup
>>> G = DihedralGroup(6)
>>> G.orbit_transversal(0)
[(5), (0 1 2 3 4 5), (0 5)(1 4)(2 3), (0 2 4)(1 3 5), (5)(0 4)(1 3), (0 3)(1 4)(2 5)]
See Also
========
orbit
"""
return _orbit_transversal(self._degree, self.generators, alpha, pairs)
def orbits(self, rep=False):
"""Return the orbits of ``self``, ordered according to lowest element
in each orbit.
Examples
========
>>> from sympy.combinatorics.permutations import Permutation
>>> from sympy.combinatorics.perm_groups import PermutationGroup
>>> a = Permutation(1, 5)(2, 3)(4, 0, 6)
>>> b = Permutation(1, 5)(3, 4)(2, 6, 0)
>>> G = PermutationGroup([a, b])
>>> G.orbits()
[{0, 2, 3, 4, 6}, {1, 5}]
"""
return _orbits(self._degree, self._generators)
def order(self):
"""Return the order of the group: the number of permutations that
can be generated from elements of the group.
The number of permutations comprising the group is given by
``len(group)``; the length of each permutation in the group is
given by ``group.size``.
Examples
========
>>> from sympy.combinatorics.permutations import Permutation
>>> from sympy.combinatorics.perm_groups import PermutationGroup
>>> a = Permutation([1, 0, 2])
>>> G = PermutationGroup([a])
>>> G.degree
3
>>> len(G)
1
>>> G.order()
2
>>> list(G.generate())
[(2), (2)(0 1)]
>>> a = Permutation([0, 2, 1])
>>> b = Permutation([1, 0, 2])
>>> G = PermutationGroup([a, b])
>>> G.order()
6
See Also
========
degree
"""
if self._order != None:
return self._order
if self._is_sym:
n = self._degree
self._order = factorial(n)
return self._order
if self._is_alt:
n = self._degree
self._order = factorial(n)/2
return self._order
basic_transversals = self.basic_transversals
m = 1
for x in basic_transversals:
m *= len(x)
self._order = m
return m
def pointwise_stabilizer(self, points, incremental=True):
r"""Return the pointwise stabilizer for a set of points.
For a permutation group `G` and a set of points
`\{p_1, p_2,\ldots, p_k\}`, the pointwise stabilizer of
`p_1, p_2, \ldots, p_k` is defined as
`G_{p_1,\ldots, p_k} =
\{g\in G | g(p_i) = p_i \forall i\in\{1, 2,\ldots,k\}\}` ([1],p20).
It is a subgroup of `G`.
Examples
========
>>> from sympy.combinatorics.named_groups import SymmetricGroup
>>> S = SymmetricGroup(7)
>>> Stab = S.pointwise_stabilizer([2, 3, 5])
>>> Stab.is_subgroup(S.stabilizer(2).stabilizer(3).stabilizer(5))
True
See Also
========
stabilizer, schreier_sims_incremental
Notes
=====
When incremental == True,
rather than the obvious implementation using successive calls to
``.stabilizer()``, this uses the incremental Schreier-Sims algorithm
to obtain a base with starting segment - the given points.
"""
if incremental:
base, strong_gens = self.schreier_sims_incremental(base=points)
stab_gens = []
degree = self.degree
for gen in strong_gens:
if [gen(point) for point in points] == points:
stab_gens.append(gen)
if not stab_gens:
stab_gens = _af_new(list(range(degree)))
return PermutationGroup(stab_gens)
else:
gens = self._generators
degree = self.degree
for x in points:
gens = _stabilizer(degree, gens, x)
return PermutationGroup(gens)
def make_perm(self, n, seed=None):
"""
Multiply ``n`` randomly selected permutations from
pgroup together, starting with the identity
permutation. If ``n`` is a list of integers, those
integers will be used to select the permutations and they
will be applied in L to R order: make_perm((A, B, C)) will
give CBA(I) where I is the identity permutation.
``seed`` is used to set the seed for the random selection
of permutations from pgroup. If this is a list of integers,
the corresponding permutations from pgroup will be selected
in the order give. This is mainly used for testing purposes.
Examples
========
>>> from sympy.combinatorics import Permutation
>>> Permutation.print_cyclic = True
>>> from sympy.combinatorics.perm_groups import PermutationGroup
>>> a, b = [Permutation([1, 0, 3, 2]), Permutation([1, 3, 0, 2])]
>>> G = PermutationGroup([a, b])
>>> G.make_perm(1, [0])
(0 1)(2 3)
>>> G.make_perm(3, [0, 1, 0])
(0 2 3 1)
>>> G.make_perm([0, 1, 0])
(0 2 3 1)
See Also
========
random
"""
if is_sequence(n):
if seed is not None:
raise ValueError('If n is a sequence, seed should be None')
n, seed = len(n), n
else:
try:
n = int(n)
except TypeError:
raise ValueError('n must be an integer or a sequence.')
randrange = _randrange(seed)
# start with the identity permutation
result = Permutation(list(range(self.degree)))
m = len(self)
for i in range(n):
p = self[randrange(m)]
result = rmul(result, p)
return result
def random(self, af=False):
"""Return a random group element
"""
rank = randrange(self.order())
return self.coset_unrank(rank, af)
def random_pr(self, gen_count=11, iterations=50, _random_prec=None):
"""Return a random group element using product replacement.
For the details of the product replacement algorithm, see
``_random_pr_init`` In ``random_pr`` the actual 'product replacement'
is performed. Notice that if the attribute ``_random_gens``
is empty, it needs to be initialized by ``_random_pr_init``.
See Also
========
_random_pr_init
"""
if self._random_gens == []:
self._random_pr_init(gen_count, iterations)
random_gens = self._random_gens
r = len(random_gens) - 1
# handle randomized input for testing purposes
if _random_prec is None:
s = randrange(r)
t = randrange(r - 1)
if t == s:
t = r - 1
x = choice([1, 2])
e = choice([-1, 1])
else:
s = _random_prec['s']
t = _random_prec['t']
if t == s:
t = r - 1
x = _random_prec['x']
e = _random_prec['e']
if x == 1:
random_gens[s] = _af_rmul(random_gens[s], _af_pow(random_gens[t], e))
random_gens[r] = _af_rmul(random_gens[r], random_gens[s])
else:
random_gens[s] = _af_rmul(_af_pow(random_gens[t], e), random_gens[s])
random_gens[r] = _af_rmul(random_gens[s], random_gens[r])
return _af_new(random_gens[r])
def random_stab(self, alpha, schreier_vector=None, _random_prec=None):
"""Random element from the stabilizer of ``alpha``.
The schreier vector for ``alpha`` is an optional argument used
for speeding up repeated calls. The algorithm is described in [1], p.81
See Also
========
random_pr, orbit_rep
"""
if schreier_vector is None:
schreier_vector = self.schreier_vector(alpha)
if _random_prec is None:
rand = self.random_pr()
else:
rand = _random_prec['rand']
beta = rand(alpha)
h = self.orbit_rep(alpha, beta, schreier_vector)
return rmul(~h, rand)
def schreier_sims(self):
"""Schreier-Sims algorithm.
It computes the generators of the chain of stabilizers
`G > G_{b_1} > .. > G_{b1,..,b_r} > 1`
in which `G_{b_1,..,b_i}` stabilizes `b_1,..,b_i`,
and the corresponding ``s`` cosets.
An element of the group can be written as the product
`h_1*..*h_s`.
We use the incremental Schreier-Sims algorithm.
Examples
========
>>> from sympy.combinatorics.permutations import Permutation
>>> from sympy.combinatorics.perm_groups import PermutationGroup
>>> a = Permutation([0, 2, 1])
>>> b = Permutation([1, 0, 2])
>>> G = PermutationGroup([a, b])
>>> G.schreier_sims()
>>> G.basic_transversals
[{0: (2)(0 1), 1: (2), 2: (1 2)},
{0: (2), 2: (0 2)}]
"""
if self._transversals:
return
self._schreier_sims()
return
def _schreier_sims(self, base=None):
schreier = self.schreier_sims_incremental(base=base, slp_dict=True)
base, strong_gens = schreier[:2]
self._base = base
self._strong_gens = strong_gens
self._strong_gens_slp = schreier[2]
if not base:
self._transversals = []
self._basic_orbits = []
return
strong_gens_distr = _distribute_gens_by_base(base, strong_gens)
basic_orbits, transversals, slps = _orbits_transversals_from_bsgs(base,\
strong_gens_distr, slp=True)
# rewrite the indices stored in slps in terms of strong_gens
for i, slp in enumerate(slps):
gens = strong_gens_distr[i]
for k in slp:
slp[k] = [strong_gens.index(gens[s]) for s in slp[k]]
self._transversals = transversals
self._basic_orbits = [sorted(x) for x in basic_orbits]
self._transversal_slp = slps
def schreier_sims_incremental(self, base=None, gens=None, slp_dict=False):
"""Extend a sequence of points and generating set to a base and strong
generating set.
Parameters
==========
base
The sequence of points to be extended to a base. Optional
parameter with default value ``[]``.
gens
The generating set to be extended to a strong generating set
relative to the base obtained. Optional parameter with default
value ``self.generators``.
slp_dict
If `True`, return a dictionary `{g: gens}` for each strong
generator `g` where `gens` is a list of strong generators
coming before `g` in `strong_gens`, such that the product
of the elements of `gens` is equal to `g`.
Returns
=======
(base, strong_gens)
``base`` is the base obtained, and ``strong_gens`` is the strong
generating set relative to it. The original parameters ``base``,
``gens`` remain unchanged.
Examples
========
>>> from sympy.combinatorics.named_groups import AlternatingGroup
>>> from sympy.combinatorics.perm_groups import PermutationGroup
>>> from sympy.combinatorics.testutil import _verify_bsgs
>>> A = AlternatingGroup(7)
>>> base = [2, 3]
>>> seq = [2, 3]
>>> base, strong_gens = A.schreier_sims_incremental(base=seq)
>>> _verify_bsgs(A, base, strong_gens)
True
>>> base[:2]
[2, 3]
Notes
=====
This version of the Schreier-Sims algorithm runs in polynomial time.
There are certain assumptions in the implementation - if the trivial
group is provided, ``base`` and ``gens`` are returned immediately,
as any sequence of points is a base for the trivial group. If the
identity is present in the generators ``gens``, it is removed as
it is a redundant generator.
The implementation is described in [1], pp. 90-93.
See Also
========
schreier_sims, schreier_sims_random
"""
if base is None:
base = []
if gens is None:
gens = self.generators[:]
degree = self.degree
id_af = list(range(degree))
# handle the trivial group
if len(gens) == 1 and gens[0].is_Identity:
if slp_dict:
return base, gens, {gens[0]: [gens[0]]}
return base, gens
# prevent side effects
_base, _gens = base[:], gens[:]
# remove the identity as a generator
_gens = [x for x in _gens if not x.is_Identity]
# make sure no generator fixes all base points
for gen in _gens:
if all(x == gen._array_form[x] for x in _base):
for new in id_af:
if gen._array_form[new] != new:
break
else:
assert None # can this ever happen?
_base.append(new)
# distribute generators according to basic stabilizers
strong_gens_distr = _distribute_gens_by_base(_base, _gens)
strong_gens_slp = []
# initialize the basic stabilizers, basic orbits and basic transversals
orbs = {}
transversals = {}
slps = {}
base_len = len(_base)
for i in range(base_len):
transversals[i], slps[i] = _orbit_transversal(degree, strong_gens_distr[i],
_base[i], pairs=True, af=True, slp=True)
transversals[i] = dict(transversals[i])
orbs[i] = list(transversals[i].keys())
# main loop: amend the stabilizer chain until we have generators
# for all stabilizers
i = base_len - 1
while i >= 0:
# this flag is used to continue with the main loop from inside
# a nested loop
continue_i = False
# test the generators for being a strong generating set
db = {}
for beta, u_beta in list(transversals[i].items()):
for j, gen in enumerate(strong_gens_distr[i]):
gb = gen._array_form[beta]
u1 = transversals[i][gb]
g1 = _af_rmul(gen._array_form, u_beta)
slp = [(i, g) for g in slps[i][beta]]
slp = [(i, j)] + slp
if g1 != u1:
# test if the schreier generator is in the i+1-th
# would-be basic stabilizer
y = True
try:
u1_inv = db[gb]
except KeyError:
u1_inv = db[gb] = _af_invert(u1)
schreier_gen = _af_rmul(u1_inv, g1)
u1_inv_slp = slps[i][gb][:]
u1_inv_slp.reverse()
u1_inv_slp = [(i, (g,)) for g in u1_inv_slp]
slp = u1_inv_slp + slp
h, j, slp = _strip_af(schreier_gen, _base, orbs, transversals, i, slp=slp, slps=slps)
if j <= base_len:
# new strong generator h at level j
y = False
elif h:
# h fixes all base points
y = False
moved = 0
while h[moved] == moved:
moved += 1
_base.append(moved)
base_len += 1
strong_gens_distr.append([])
if y is False:
# if a new strong generator is found, update the
# data structures and start over
h = _af_new(h)
strong_gens_slp.append((h, slp))
for l in range(i + 1, j):
strong_gens_distr[l].append(h)
transversals[l], slps[l] =\
_orbit_transversal(degree, strong_gens_distr[l],
_base[l], pairs=True, af=True, slp=True)
transversals[l] = dict(transversals[l])
orbs[l] = list(transversals[l].keys())
i = j - 1
# continue main loop using the flag
continue_i = True
if continue_i is True:
break
if continue_i is True:
break
if continue_i is True:
continue
i -= 1
strong_gens = _gens[:]
if slp_dict:
# create the list of the strong generators strong_gens and
# rewrite the indices of strong_gens_slp in terms of the
# elements of strong_gens
for k, slp in strong_gens_slp:
strong_gens.append(k)
for i in range(len(slp)):
s = slp[i]
if isinstance(s[1], tuple):
slp[i] = strong_gens_distr[s[0]][s[1][0]]**-1
else:
slp[i] = strong_gens_distr[s[0]][s[1]]
strong_gens_slp = dict(strong_gens_slp)
# add the original generators
for g in _gens:
strong_gens_slp[g] = [g]
return (_base, strong_gens, strong_gens_slp)
strong_gens.extend([k for k, _ in strong_gens_slp])
return _base, strong_gens
def schreier_sims_random(self, base=None, gens=None, consec_succ=10,
_random_prec=None):
r"""Randomized Schreier-Sims algorithm.
The randomized Schreier-Sims algorithm takes the sequence ``base``
and the generating set ``gens``, and extends ``base`` to a base, and
``gens`` to a strong generating set relative to that base with
probability of a wrong answer at most `2^{-consec\_succ}`,
provided the random generators are sufficiently random.
Parameters
==========
base
The sequence to be extended to a base.
gens
The generating set to be extended to a strong generating set.
consec_succ
The parameter defining the probability of a wrong answer.
_random_prec
An internal parameter used for testing purposes.
Returns
=======
(base, strong_gens)
``base`` is the base and ``strong_gens`` is the strong generating
set relative to it.
Examples
========
>>> from sympy.combinatorics.perm_groups import PermutationGroup
>>> from sympy.combinatorics.testutil import _verify_bsgs
>>> from sympy.combinatorics.named_groups import SymmetricGroup
>>> S = SymmetricGroup(5)
>>> base, strong_gens = S.schreier_sims_random(consec_succ=5)
>>> _verify_bsgs(S, base, strong_gens) #doctest: +SKIP
True
Notes
=====
The algorithm is described in detail in [1], pp. 97-98. It extends
the orbits ``orbs`` and the permutation groups ``stabs`` to
basic orbits and basic stabilizers for the base and strong generating
set produced in the end.
The idea of the extension process
is to "sift" random group elements through the stabilizer chain
and amend the stabilizers/orbits along the way when a sift
is not successful.
The helper function ``_strip`` is used to attempt
to decompose a random group element according to the current
state of the stabilizer chain and report whether the element was
fully decomposed (successful sift) or not (unsuccessful sift). In
the latter case, the level at which the sift failed is reported and
used to amend ``stabs``, ``base``, ``gens`` and ``orbs`` accordingly.
The halting condition is for ``consec_succ`` consecutive successful
sifts to pass. This makes sure that the current ``base`` and ``gens``
form a BSGS with probability at least `1 - 1/\text{consec\_succ}`.
See Also
========
schreier_sims
"""
if base is None:
base = []
if gens is None:
gens = self.generators
base_len = len(base)
n = self.degree
# make sure no generator fixes all base points
for gen in gens:
if all(gen(x) == x for x in base):
new = 0
while gen._array_form[new] == new:
new += 1
base.append(new)
base_len += 1
# distribute generators according to basic stabilizers
strong_gens_distr = _distribute_gens_by_base(base, gens)
# initialize the basic stabilizers, basic transversals and basic orbits
transversals = {}
orbs = {}
for i in range(base_len):
transversals[i] = dict(_orbit_transversal(n, strong_gens_distr[i],
base[i], pairs=True))
orbs[i] = list(transversals[i].keys())
# initialize the number of consecutive elements sifted
c = 0
# start sifting random elements while the number of consecutive sifts
# is less than consec_succ
while c < consec_succ:
if _random_prec is None:
g = self.random_pr()
else:
g = _random_prec['g'].pop()
h, j = _strip(g, base, orbs, transversals)
y = True
# determine whether a new base point is needed
if j <= base_len:
y = False
elif not h.is_Identity:
y = False
moved = 0
while h(moved) == moved:
moved += 1
base.append(moved)
base_len += 1
strong_gens_distr.append([])
# if the element doesn't sift, amend the strong generators and
# associated stabilizers and orbits
if y is False:
for l in range(1, j):
strong_gens_distr[l].append(h)
transversals[l] = dict(_orbit_transversal(n,
strong_gens_distr[l], base[l], pairs=True))
orbs[l] = list(transversals[l].keys())
c = 0
else:
c += 1
# build the strong generating set
strong_gens = strong_gens_distr[0][:]
for gen in strong_gens_distr[1]:
if gen not in strong_gens:
strong_gens.append(gen)
return base, strong_gens
def schreier_vector(self, alpha):
"""Computes the schreier vector for ``alpha``.
The Schreier vector efficiently stores information
about the orbit of ``alpha``. It can later be used to quickly obtain
elements of the group that send ``alpha`` to a particular element
in the orbit. Notice that the Schreier vector depends on the order
in which the group generators are listed. For a definition, see [3].
Since list indices start from zero, we adopt the convention to use
"None" instead of 0 to signify that an element doesn't belong
to the orbit.
For the algorithm and its correctness, see [2], pp.78-80.
Examples
========
>>> from sympy.combinatorics.perm_groups import PermutationGroup
>>> from sympy.combinatorics.permutations import Permutation
>>> a = Permutation([2, 4, 6, 3, 1, 5, 0])
>>> b = Permutation([0, 1, 3, 5, 4, 6, 2])
>>> G = PermutationGroup([a, b])
>>> G.schreier_vector(0)
[-1, None, 0, 1, None, 1, 0]
See Also
========
orbit
"""
n = self.degree
v = [None]*n
v[alpha] = -1
orb = [alpha]
used = [False]*n
used[alpha] = True
gens = self.generators
r = len(gens)
for b in orb:
for i in range(r):
temp = gens[i]._array_form[b]
if used[temp] is False:
orb.append(temp)
used[temp] = True
v[temp] = i
return v
def stabilizer(self, alpha):
r"""Return the stabilizer subgroup of ``alpha``.
The stabilizer of `\alpha` is the group `G_\alpha =
\{g \in G | g(\alpha) = \alpha\}`.
For a proof of correctness, see [1], p.79.
Examples
========
>>> from sympy.combinatorics import Permutation
>>> Permutation.print_cyclic = True
>>> from sympy.combinatorics.perm_groups import PermutationGroup
>>> from sympy.combinatorics.named_groups import DihedralGroup
>>> G = DihedralGroup(6)
>>> G.stabilizer(5)
PermutationGroup([
(5)(0 4)(1 3)])
See Also
========
orbit
"""
return PermGroup(_stabilizer(self._degree, self._generators, alpha))
@property
def strong_gens(self):
r"""Return a strong generating set from the Schreier-Sims algorithm.
A generating set `S = \{g_1, g_2, ..., g_t\}` for a permutation group
`G` is a strong generating set relative to the sequence of points
(referred to as a "base") `(b_1, b_2, ..., b_k)` if, for
`1 \leq i \leq k` we have that the intersection of the pointwise
stabilizer `G^{(i+1)} := G_{b_1, b_2, ..., b_i}` with `S` generates
the pointwise stabilizer `G^{(i+1)}`. The concepts of a base and
strong generating set and their applications are discussed in depth
in [1], pp. 87-89 and [2], pp. 55-57.
Examples
========
>>> from sympy.combinatorics.named_groups import DihedralGroup
>>> D = DihedralGroup(4)
>>> D.strong_gens
[(0 1 2 3), (0 3)(1 2), (1 3)]
>>> D.base
[0, 1]
See Also
========
base, basic_transversals, basic_orbits, basic_stabilizers
"""
if self._strong_gens == []:
self.schreier_sims()
return self._strong_gens
def subgroup(self, gens):
"""
Return the subgroup generated by `gens` which is a list of
elements of the group
"""
if not all([g in self for g in gens]):
raise ValueError("The group doesn't contain the supplied generators")
G = PermutationGroup(gens)
return G
def subgroup_search(self, prop, base=None, strong_gens=None, tests=None,
init_subgroup=None):
"""Find the subgroup of all elements satisfying the property ``prop``.
This is done by a depth-first search with respect to base images that
uses several tests to prune the search tree.
Parameters
==========
prop
The property to be used. Has to be callable on group elements
and always return ``True`` or ``False``. It is assumed that
all group elements satisfying ``prop`` indeed form a subgroup.
base
A base for the supergroup.
strong_gens
A strong generating set for the supergroup.
tests
A list of callables of length equal to the length of ``base``.
These are used to rule out group elements by partial base images,
so that ``tests[l](g)`` returns False if the element ``g`` is known
not to satisfy prop base on where g sends the first ``l + 1`` base
points.
init_subgroup
if a subgroup of the sought group is
known in advance, it can be passed to the function as this
parameter.
Returns
=======
res
The subgroup of all elements satisfying ``prop``. The generating
set for this group is guaranteed to be a strong generating set
relative to the base ``base``.
Examples
========
>>> from sympy.combinatorics.named_groups import (SymmetricGroup,
... AlternatingGroup)
>>> from sympy.combinatorics.perm_groups import PermutationGroup
>>> from sympy.combinatorics.testutil import _verify_bsgs
>>> S = SymmetricGroup(7)
>>> prop_even = lambda x: x.is_even
>>> base, strong_gens = S.schreier_sims_incremental()
>>> G = S.subgroup_search(prop_even, base=base, strong_gens=strong_gens)
>>> G.is_subgroup(AlternatingGroup(7))
True
>>> _verify_bsgs(G, base, G.generators)
True
Notes
=====
This function is extremely lengthy and complicated and will require
some careful attention. The implementation is described in
[1], pp. 114-117, and the comments for the code here follow the lines
of the pseudocode in the book for clarity.
The complexity is exponential in general, since the search process by
itself visits all members of the supergroup. However, there are a lot
of tests which are used to prune the search tree, and users can define
their own tests via the ``tests`` parameter, so in practice, and for
some computations, it's not terrible.
A crucial part in the procedure is the frequent base change performed
(this is line 11 in the pseudocode) in order to obtain a new basic
stabilizer. The book mentiones that this can be done by using
``.baseswap(...)``, however the current implementation uses a more
straightforward way to find the next basic stabilizer - calling the
function ``.stabilizer(...)`` on the previous basic stabilizer.
"""
# initialize BSGS and basic group properties
def get_reps(orbits):
# get the minimal element in the base ordering
return [min(orbit, key = lambda x: base_ordering[x]) \
for orbit in orbits]
def update_nu(l):
temp_index = len(basic_orbits[l]) + 1 -\
len(res_basic_orbits_init_base[l])
# this corresponds to the element larger than all points
if temp_index >= len(sorted_orbits[l]):
nu[l] = base_ordering[degree]
else:
nu[l] = sorted_orbits[l][temp_index]
if base is None:
base, strong_gens = self.schreier_sims_incremental()
base_len = len(base)
degree = self.degree
identity = _af_new(list(range(degree)))
base_ordering = _base_ordering(base, degree)
# add an element larger than all points
base_ordering.append(degree)
# add an element smaller than all points
base_ordering.append(-1)
# compute BSGS-related structures
strong_gens_distr = _distribute_gens_by_base(base, strong_gens)
basic_orbits, transversals = _orbits_transversals_from_bsgs(base,
strong_gens_distr)
# handle subgroup initialization and tests
if init_subgroup is None:
init_subgroup = PermutationGroup([identity])
if tests is None:
trivial_test = lambda x: True
tests = []
for i in range(base_len):
tests.append(trivial_test)
# line 1: more initializations.
res = init_subgroup
f = base_len - 1
l = base_len - 1
# line 2: set the base for K to the base for G
res_base = base[:]
# line 3: compute BSGS and related structures for K
res_base, res_strong_gens = res.schreier_sims_incremental(
base=res_base)
res_strong_gens_distr = _distribute_gens_by_base(res_base,
res_strong_gens)
res_generators = res.generators
res_basic_orbits_init_base = \
[_orbit(degree, res_strong_gens_distr[i], res_base[i])\
for i in range(base_len)]
# initialize orbit representatives
orbit_reps = [None]*base_len
# line 4: orbit representatives for f-th basic stabilizer of K
orbits = _orbits(degree, res_strong_gens_distr[f])
orbit_reps[f] = get_reps(orbits)
# line 5: remove the base point from the representatives to avoid
# getting the identity element as a generator for K
orbit_reps[f].remove(base[f])
# line 6: more initializations
c = [0]*base_len
u = [identity]*base_len
sorted_orbits = [None]*base_len
for i in range(base_len):
sorted_orbits[i] = basic_orbits[i][:]
sorted_orbits[i].sort(key=lambda point: base_ordering[point])
# line 7: initializations
mu = [None]*base_len
nu = [None]*base_len
# this corresponds to the element smaller than all points
mu[l] = degree + 1
update_nu(l)
# initialize computed words
computed_words = [identity]*base_len
# line 8: main loop
while True:
# apply all the tests
while l < base_len - 1 and \
computed_words[l](base[l]) in orbit_reps[l] and \
base_ordering[mu[l]] < \
base_ordering[computed_words[l](base[l])] < \
base_ordering[nu[l]] and \
tests[l](computed_words):
# line 11: change the (partial) base of K
new_point = computed_words[l](base[l])
res_base[l] = new_point
new_stab_gens = _stabilizer(degree, res_strong_gens_distr[l],
new_point)
res_strong_gens_distr[l + 1] = new_stab_gens
# line 12: calculate minimal orbit representatives for the
# l+1-th basic stabilizer
orbits = _orbits(degree, new_stab_gens)
orbit_reps[l + 1] = get_reps(orbits)
# line 13: amend sorted orbits
l += 1
temp_orbit = [computed_words[l - 1](point) for point
in basic_orbits[l]]
temp_orbit.sort(key=lambda point: base_ordering[point])
sorted_orbits[l] = temp_orbit
# lines 14 and 15: update variables used minimality tests
new_mu = degree + 1
for i in range(l):
if base[l] in res_basic_orbits_init_base[i]:
candidate = computed_words[i](base[i])
if base_ordering[candidate] > base_ordering[new_mu]:
new_mu = candidate
mu[l] = new_mu
update_nu(l)
# line 16: determine the new transversal element
c[l] = 0
temp_point = sorted_orbits[l][c[l]]
gamma = computed_words[l - 1]._array_form.index(temp_point)
u[l] = transversals[l][gamma]
# update computed words
computed_words[l] = rmul(computed_words[l - 1], u[l])
# lines 17 & 18: apply the tests to the group element found
g = computed_words[l]
temp_point = g(base[l])
if l == base_len - 1 and \
base_ordering[mu[l]] < \
base_ordering[temp_point] < base_ordering[nu[l]] and \
temp_point in orbit_reps[l] and \
tests[l](computed_words) and \
prop(g):
# line 19: reset the base of K
res_generators.append(g)
res_base = base[:]
# line 20: recalculate basic orbits (and transversals)
res_strong_gens.append(g)
res_strong_gens_distr = _distribute_gens_by_base(res_base,
res_strong_gens)
res_basic_orbits_init_base = \
[_orbit(degree, res_strong_gens_distr[i], res_base[i]) \
for i in range(base_len)]
# line 21: recalculate orbit representatives
# line 22: reset the search depth
orbit_reps[f] = get_reps(orbits)
l = f
# line 23: go up the tree until in the first branch not fully
# searched
while l >= 0 and c[l] == len(basic_orbits[l]) - 1:
l = l - 1
# line 24: if the entire tree is traversed, return K
if l == -1:
return PermutationGroup(res_generators)
# lines 25-27: update orbit representatives
if l < f:
# line 26
f = l
c[l] = 0
# line 27
temp_orbits = _orbits(degree, res_strong_gens_distr[f])
orbit_reps[f] = get_reps(temp_orbits)
# line 28: update variables used for minimality testing
mu[l] = degree + 1
temp_index = len(basic_orbits[l]) + 1 - \
len(res_basic_orbits_init_base[l])
if temp_index >= len(sorted_orbits[l]):
nu[l] = base_ordering[degree]
else:
nu[l] = sorted_orbits[l][temp_index]
# line 29: set the next element from the current branch and update
# accordingly
c[l] += 1
if l == 0:
gamma = sorted_orbits[l][c[l]]
else:
gamma = computed_words[l - 1]._array_form.index(sorted_orbits[l][c[l]])
u[l] = transversals[l][gamma]
if l == 0:
computed_words[l] = u[l]
else:
computed_words[l] = rmul(computed_words[l - 1], u[l])
@property
def transitivity_degree(self):
r"""Compute the degree of transitivity of the group.
A permutation group `G` acting on `\Omega = \{0, 1, ..., n-1\}` is
``k``-fold transitive, if, for any k points
`(a_1, a_2, ..., a_k)\in\Omega` and any k points
`(b_1, b_2, ..., b_k)\in\Omega` there exists `g\in G` such that
`g(a_1)=b_1, g(a_2)=b_2, ..., g(a_k)=b_k`
The degree of transitivity of `G` is the maximum ``k`` such that
`G` is ``k``-fold transitive. ([8])
Examples
========
>>> from sympy.combinatorics.perm_groups import PermutationGroup
>>> from sympy.combinatorics.permutations import Permutation
>>> a = Permutation([1, 2, 0])
>>> b = Permutation([1, 0, 2])
>>> G = PermutationGroup([a, b])
>>> G.transitivity_degree
3
See Also
========
is_transitive, orbit
"""
if self._transitivity_degree is None:
n = self.degree
G = self
# if G is k-transitive, a tuple (a_0,..,a_k)
# can be brought to (b_0,...,b_(k-1), b_k)
# where b_0,...,b_(k-1) are fixed points;
# consider the group G_k which stabilizes b_0,...,b_(k-1)
# if G_k is transitive on the subset excluding b_0,...,b_(k-1)
# then G is (k+1)-transitive
for i in range(n):
orb = G.orbit((i))
if len(orb) != n - i:
self._transitivity_degree = i
return i
G = G.stabilizer(i)
self._transitivity_degree = n
return n
else:
return self._transitivity_degree
def _p_elements_group(G, p):
'''
For an abelian p-group G return the subgroup consisting of
all elements of order p (and the identity)
'''
gens = G.generators[:]
gens = sorted(gens, key=lambda x: x.order(), reverse=True)
gens_p = [g**(g.order()/p) for g in gens]
gens_r = []
for i in range(len(gens)):
x = gens[i]
x_order = x.order()
# x_p has order p
x_p = x**(x_order/p)
if i > 0:
P = PermutationGroup(gens_p[:i])
else:
P = PermutationGroup(G.identity)
if x**(x_order/p) not in P:
gens_r.append(x**(x_order/p))
else:
# replace x by an element of order (x.order()/p)
# so that gens still generates G
g = P.generator_product(x_p, original=True)
for s in g:
x = x*s**-1
x_order = x_order/p
# insert x to gens so that the sorting is preserved
del gens[i]
del gens_p[i]
j = i - 1
while j < len(gens) and gens[j].order() >= x_order:
j += 1
gens = gens[:j] + [x] + gens[j:]
gens_p = gens_p[:j] + [x] + gens_p[j:]
return PermutationGroup(gens_r)
def _sylow_alt_sym(self, p):
'''
Return a p-Sylow subgroup of a symmetric or an
alternating group.
The algorithm for this is hinted at in [1], Chapter 4,
Exercise 4.
For Sym(n) with n = p^i, the idea is as follows. Partition
the interval [0..n-1] into p equal parts, each of length p^(i-1):
[0..p^(i-1)-1], [p^(i-1)..2*p^(i-1)-1]...[(p-1)*p^(i-1)..p^i-1].
Find a p-Sylow subgroup of Sym(p^(i-1)) (treated as a subgroup
of `self`) acting on each of the parts. Call the subgroups
P_1, P_2...P_p. The generators for the subgroups P_2...P_p
can be obtained from those of P_1 by applying a "shifting"
permutation to them, that is, a permutation mapping [0..p^(i-1)-1]
to the second part (the other parts are obtained by using the shift
multiple times). The union of this permutation and the generators
of P_1 is a p-Sylow subgroup of `self`.
For n not equal to a power of p, partition
[0..n-1] in accordance with how n would be written in base p.
E.g. for p=2 and n=11, 11 = 2^3 + 2^2 + 1 so the partition
is [[0..7], [8..9], {10}]. To generate a p-Sylow subgroup,
take the union of the generators for each of the parts.
For the above example, {(0 1), (0 2)(1 3), (0 4), (1 5)(2 7)}
from the first part, {(8 9)} from the second part and
nothing from the third. This gives 4 generators in total, and
the subgroup they generate is p-Sylow.
Alternating groups are treated the same except when p=2. In this
case, (0 1)(s s+1) should be added for an appropriate s (the start
of a part) for each part in the partitions.
See Also
========
sylow_subgroup, is_alt_sym
'''
n = self.degree
gens = []
identity = Permutation(n-1)
# the case of 2-sylow subgroups of alternating groups
# needs special treatment
alt = p == 2 and all(g.is_even for g in self.generators)
# find the presentation of n in base p
coeffs = []
m = n
while m > 0:
coeffs.append(m % p)
m = m // p
power = len(coeffs)-1
# for a symmetric group, gens[:i] is the generating
# set for a p-Sylow subgroup on [0..p**(i-1)-1]. For
# alternating groups, the same is given by gens[:2*(i-1)]
for i in range(1, power+1):
if i == 1 and alt:
# (0 1) shouldn't be added for alternating groups
continue
gen = Permutation([(j + p**(i-1)) % p**i for j in range(p**i)])
gens.append(identity*gen)
if alt:
gen = Permutation(0, 1)*gen*Permutation(0, 1)*gen
gens.append(gen)
# the first point in the current part (see the algorithm
# description in the docstring)
start = 0
while power > 0:
a = coeffs[power]
# make the permutation shifting the start of the first
# part ([0..p^i-1] for some i) to the current one
for s in range(a):
shift = Permutation()
if start > 0:
for i in range(p**power):
shift = shift(i, start + i)
if alt:
gen = Permutation(0, 1)*shift*Permutation(0, 1)*shift
gens.append(gen)
j = 2*(power - 1)
else:
j = power
for i, gen in enumerate(gens[:j]):
if alt and i % 2 == 1:
continue
# shift the generator to the start of the
# partition part
gen = shift*gen*shift
gens.append(gen)
start += p**power
power = power-1
return gens
def sylow_subgroup(self, p):
'''
Return a p-Sylow subgroup of the group.
The algorithm is described in [1], Chapter 4, Section 7
Examples
========
>>> from sympy.combinatorics.named_groups import DihedralGroup
>>> from sympy.combinatorics.named_groups import SymmetricGroup
>>> from sympy.combinatorics.named_groups import AlternatingGroup
>>> D = DihedralGroup(6)
>>> S = D.sylow_subgroup(2)
>>> S.order()
4
>>> G = SymmetricGroup(6)
>>> S = G.sylow_subgroup(5)
>>> S.order()
5
>>> G1 = AlternatingGroup(3)
>>> G2 = AlternatingGroup(5)
>>> G3 = AlternatingGroup(9)
>>> S1 = G1.sylow_subgroup(3)
>>> S2 = G2.sylow_subgroup(3)
>>> S3 = G3.sylow_subgroup(3)
>>> len1 = len(S1.lower_central_series())
>>> len2 = len(S2.lower_central_series())
>>> len3 = len(S3.lower_central_series())
>>> len1 == len2
True
>>> len1 < len3
True
'''
from sympy.combinatorics.homomorphisms import (
orbit_homomorphism, block_homomorphism)
from sympy.ntheory.primetest import isprime
if not isprime(p):
raise ValueError("p must be a prime")
def is_p_group(G):
# check if the order of G is a power of p
# and return the power
m = G.order()
n = 0
while m % p == 0:
m = m/p
n += 1
if m == 1:
return True, n
return False, n
def _sylow_reduce(mu, nu):
# reduction based on two homomorphisms
# mu and nu with trivially intersecting
# kernels
Q = mu.image().sylow_subgroup(p)
Q = mu.invert_subgroup(Q)
nu = nu.restrict_to(Q)
R = nu.image().sylow_subgroup(p)
return nu.invert_subgroup(R)
order = self.order()
if order % p != 0:
return PermutationGroup([self.identity])
p_group, n = is_p_group(self)
if p_group:
return self
if self.is_alt_sym():
return PermutationGroup(self._sylow_alt_sym(p))
# if there is a non-trivial orbit with size not divisible
# by p, the sylow subgroup is contained in its stabilizer
# (by orbit-stabilizer theorem)
orbits = self.orbits()
non_p_orbits = [o for o in orbits if len(o) % p != 0 and len(o) != 1]
if non_p_orbits:
G = self.stabilizer(list(non_p_orbits[0]).pop())
return G.sylow_subgroup(p)
if not self.is_transitive():
# apply _sylow_reduce to orbit actions
orbits = sorted(orbits, key = lambda x: len(x))
omega1 = orbits.pop()
omega2 = orbits[0].union(*orbits)
mu = orbit_homomorphism(self, omega1)
nu = orbit_homomorphism(self, omega2)
return _sylow_reduce(mu, nu)
blocks = self.minimal_blocks()
if len(blocks) > 1:
# apply _sylow_reduce to block system actions
mu = block_homomorphism(self, blocks[0])
nu = block_homomorphism(self, blocks[1])
return _sylow_reduce(mu, nu)
elif len(blocks) == 1:
block = list(blocks)[0]
if any(e != 0 for e in block):
# self is imprimitive
mu = block_homomorphism(self, block)
if not is_p_group(mu.image())[0]:
S = mu.image().sylow_subgroup(p)
return mu.invert_subgroup(S).sylow_subgroup(p)
# find an element of order p
g = self.random()
g_order = g.order()
while g_order % p != 0 or g_order == 0:
g = self.random()
g_order = g.order()
g = g**(g_order // p)
if order % p**2 != 0:
return PermutationGroup(g)
C = self.centralizer(g)
while C.order() % p**n != 0:
S = C.sylow_subgroup(p)
s_order = S.order()
Z = S.center()
P = Z._p_elements_group(p)
h = P.random()
C_h = self.centralizer(h)
while C_h.order() % p*s_order != 0:
h = P.random()
C_h = self.centralizer(h)
C = C_h
return C.sylow_subgroup(p)
def _block_verify(H, L, alpha):
delta = sorted(list(H.orbit(alpha)))
H_gens = H.generators
# p[i] will be the number of the block
# delta[i] belongs to
p = [-1]*len(delta)
blocks = [-1]*len(delta)
B = [[]] # future list of blocks
u = [0]*len(delta) # u[i] in L s.t. alpha^u[i] = B[0][i]
t = L.orbit_transversal(alpha, pairs=True)
for a, beta in t:
B[0].append(a)
i_a = delta.index(a)
p[i_a] = 0
blocks[i_a] = alpha
u[i_a] = beta
rho = 0
m = 0 # number of blocks - 1
while rho <= m:
beta = B[rho][0]
for g in H_gens:
d = beta^g
i_d = delta.index(d)
sigma = p[i_d]
if sigma < 0:
# define a new block
m += 1
sigma = m
u[i_d] = u[delta.index(beta)]*g
p[i_d] = sigma
rep = d
blocks[i_d] = rep
newb = [rep]
for gamma in B[rho][1:]:
i_gamma = delta.index(gamma)
d = gamma^g
i_d = delta.index(d)
if p[i_d] < 0:
u[i_d] = u[i_gamma]*g
p[i_d] = sigma
blocks[i_d] = rep
newb.append(d)
else:
# B[rho] is not a block
s = u[i_gamma]*g*u[i_d]**(-1)
return False, s
B.append(newb)
else:
for h in B[rho][1:]:
if not h^g in B[sigma]:
# B[rho] is not a block
s = u[delta.index(beta)]*g*u[i_d]**(-1)
return False, s
rho += 1
return True, blocks
def _verify(H, K, phi, z, alpha):
'''
Return a list of relators `rels` in generators `gens_h` that
are mapped to `H.generators` by `phi` so that given a finite
presentation <gens_k | rels_k> of `K` on a subset of `gens_h`
<gens_h | rels_k + rels> is a finite presentation of `H`.
`H` should be generated by the union of `K.generators` and `z`
(a single generator), and `H.stabilizer(alpha) == K`; `phi` is a
canonical injection from a free group into a permutation group
containing `H`.
The algorithm is described in [1], Chapter 6.
Examples
========
>>> from sympy.combinatorics.perm_groups import PermutationGroup
>>> from sympy.combinatorics import Permutation
>>> from sympy.combinatorics.homomorphisms import homomorphism
>>> from sympy.combinatorics.free_groups import free_group
>>> from sympy.combinatorics.fp_groups import FpGroup
>>> H = PermutationGroup(Permutation(0, 2), Permutation (1, 5))
>>> K = PermutationGroup(Permutation(5)(0, 2))
>>> F = free_group("x_0 x_1")[0]
>>> gens = F.generators
>>> phi = homomorphism(F, H, F.generators, H.generators)
>>> rels_k = [gens[0]**2] # relators for presentation of K
>>> z= Permutation(1, 5)
>>> check, rels_h = H._verify(K, phi, z, 1)
>>> check
True
>>> rels = rels_k + rels_h
>>> G = FpGroup(F, rels) # presentation of H
>>> G.order() == H.order()
True
See also
========
strong_presentation, presentation, stabilizer
'''
orbit = H.orbit(alpha)
beta = alpha^(z**-1)
K_beta = K.stabilizer(beta)
# orbit representatives of K_beta
gammas = [alpha, beta]
orbits = list(set(tuple(K_beta.orbit(o)) for o in orbit))
orbit_reps = [orb[0] for orb in orbits]
for rep in orbit_reps:
if rep not in gammas:
gammas.append(rep)
# orbit transversal of K
betas = [alpha, beta]
transversal = {alpha: phi.invert(H.identity), beta: phi.invert(z**-1)}
for s, g in K.orbit_transversal(beta, pairs=True):
if not s in transversal:
transversal[s] = transversal[beta]*phi.invert(g)
union = K.orbit(alpha).union(K.orbit(beta))
while (len(union) < len(orbit)):
for gamma in gammas:
if gamma in union:
r = gamma^z
if r not in union:
betas.append(r)
transversal[r] = transversal[gamma]*phi.invert(z)
for s, g in K.orbit_transversal(r, pairs=True):
if not s in transversal:
transversal[s] = transversal[r]*phi.invert(g)
union = union.union(K.orbit(r))
break
# compute relators
rels = []
for b in betas:
k_gens = K.stabilizer(b).generators
for y in k_gens:
new_rel = transversal[b]
gens = K.generator_product(y, original=True)
for g in gens[::-1]:
new_rel = new_rel*phi.invert(g)
new_rel = new_rel*transversal[b]**-1
perm = phi(new_rel)
try:
gens = K.generator_product(perm, original=True)
except ValueError:
return False, perm
for g in gens:
new_rel = new_rel*phi.invert(g)**-1
if new_rel not in rels:
rels.append(new_rel)
for gamma in gammas:
new_rel = transversal[gamma]*phi.invert(z)*transversal[gamma^z]**-1
perm = phi(new_rel)
try:
gens = K.generator_product(perm, original=True)
except ValueError:
return False, perm
for g in gens:
new_rel = new_rel*phi.invert(g)**-1
if new_rel not in rels:
rels.append(new_rel)
return True, rels
def strong_presentation(G):
'''
Return a strong finite presentation of `G`. The generators
of the returned group are in the same order as the strong
generators of `G`.
The algorithm is based on Sims' Verify algorithm described
in [1], Chapter 6.
Examples
========
>>> from sympy.combinatorics.perm_groups import PermutationGroup
>>> from sympy.combinatorics.named_groups import DihedralGroup
>>> P = DihedralGroup(4)
>>> G = P.strong_presentation()
>>> P.order() == G.order()
True
See Also
========
presentation, _verify
'''
from sympy.combinatorics.fp_groups import (FpGroup,
simplify_presentation)
from sympy.combinatorics.free_groups import free_group
from sympy.combinatorics.homomorphisms import (block_homomorphism,
homomorphism, GroupHomomorphism)
strong_gens = G.strong_gens[:]
stabs = G.basic_stabilizers[:]
base = G.base[:]
# injection from a free group on len(strong_gens)
# generators into G
gen_syms = [('x_%d'%i) for i in range(len(strong_gens))]
F = free_group(', '.join(gen_syms))[0]
phi = homomorphism(F, G, F.generators, strong_gens)
H = PermutationGroup(G.identity)
while stabs:
alpha = base.pop()
K = H
H = stabs.pop()
new_gens = [g for g in H.generators if g not in K]
if K.order() == 1:
z = new_gens.pop()
rels = [F.generators[-1]**z.order()]
intermediate_gens = [z]
K = PermutationGroup(intermediate_gens)
# add generators one at a time building up from K to H
while new_gens:
z = new_gens.pop()
intermediate_gens = [z] + intermediate_gens
K_s = PermutationGroup(intermediate_gens)
orbit = K_s.orbit(alpha)
orbit_k = K.orbit(alpha)
# split into cases based on the orbit of K_s
if orbit_k == orbit:
if z in K:
rel = phi.invert(z)
perm = z
else:
t = K.orbit_rep(alpha, alpha^z)
rel = phi.invert(z)*phi.invert(t)**-1
perm = z*t**-1
for g in K.generator_product(perm, original=True):
rel = rel*phi.invert(g)**-1
new_rels = [rel]
elif len(orbit_k) == 1:
# `success` is always true because `strong_gens`
# and `base` are already a verified BSGS. Later
# this could be changed to start with a randomly
# generated (potential) BSGS, and then new elements
# would have to be appended to it when `success`
# is false.
success, new_rels = K_s._verify(K, phi, z, alpha)
else:
# K.orbit(alpha) should be a block
# under the action of K_s on K_s.orbit(alpha)
check, block = K_s._block_verify(K, alpha)
if check:
# apply _verify to the action of K_s
# on the block system; for convenience,
# add the blocks as additional points
# that K_s should act on
t = block_homomorphism(K_s, block)
m = t.codomain.degree # number of blocks
d = K_s.degree
# conjugating with p will shift
# permutations in t.image() to
# higher numbers, e.g.
# p*(0 1)*p = (m m+1)
p = Permutation()
for i in range(m):
p *= Permutation(i, i+d)
t_img = t.images
# combine generators of K_s with their
# action on the block system
images = {g: g*p*t_img[g]*p for g in t_img}
for g in G.strong_gens[:-len(K_s.generators)]:
images[g] = g
K_s_act = PermutationGroup(list(images.values()))
f = GroupHomomorphism(G, K_s_act, images)
K_act = PermutationGroup([f(g) for g in K.generators])
success, new_rels = K_s_act._verify(K_act, f.compose(phi), f(z), d)
for n in new_rels:
if not n in rels:
rels.append(n)
K = K_s
group = FpGroup(F, rels)
return simplify_presentation(group)
def presentation(G, eliminate_gens=True):
'''
Return an `FpGroup` presentation of the group.
The algorithm is described in [1], Chapter 6.1.
'''
from sympy.combinatorics.fp_groups import (FpGroup,
simplify_presentation)
from sympy.combinatorics.coset_table import CosetTable
from sympy.combinatorics.free_groups import free_group
from sympy.combinatorics.homomorphisms import homomorphism
from itertools import product
if G._fp_presentation:
return G._fp_presentation
if G._fp_presentation:
return G._fp_presentation
def _factor_group_by_rels(G, rels):
if isinstance(G, FpGroup):
rels.extend(G.relators)
return FpGroup(G.free_group, list(set(rels)))
return FpGroup(G, rels)
gens = G.generators
len_g = len(gens)
if len_g == 1:
order = gens[0].order()
# handle the trivial group
if order == 1:
return free_group([])[0]
F, x = free_group('x')
return FpGroup(F, [x**order])
if G.order() > 20:
half_gens = G.generators[0:(len_g+1)//2]
else:
half_gens = []
H = PermutationGroup(half_gens)
H_p = H.presentation()
len_h = len(H_p.generators)
C = G.coset_table(H)
n = len(C) # subgroup index
gen_syms = [('x_%d'%i) for i in range(len(gens))]
F = free_group(', '.join(gen_syms))[0]
# mapping generators of H_p to those of F
images = [F.generators[i] for i in range(len_h)]
R = homomorphism(H_p, F, H_p.generators, images, check=False)
# rewrite relators
rels = R(H_p.relators)
G_p = FpGroup(F, rels)
# injective homomorphism from G_p into G
T = homomorphism(G_p, G, G_p.generators, gens)
C_p = CosetTable(G_p, [])
C_p.table = [[None]*(2*len_g) for i in range(n)]
# initiate the coset transversal
transversal = [None]*n
transversal[0] = G_p.identity
# fill in the coset table as much as possible
for i in range(2*len_h):
C_p.table[0][i] = 0
gamma = 1
for alpha, x in product(range(0, n), range(2*len_g)):
beta = C[alpha][x]
if beta == gamma:
gen = G_p.generators[x//2]**((-1)**(x % 2))
transversal[beta] = transversal[alpha]*gen
C_p.table[alpha][x] = beta
C_p.table[beta][x + (-1)**(x % 2)] = alpha
gamma += 1
if gamma == n:
break
C_p.p = list(range(n))
beta = x = 0
while not C_p.is_complete():
# find the first undefined entry
while C_p.table[beta][x] == C[beta][x]:
x = (x + 1) % (2*len_g)
if x == 0:
beta = (beta + 1) % n
# define a new relator
gen = G_p.generators[x//2]**((-1)**(x % 2))
new_rel = transversal[beta]*gen*transversal[C[beta][x]]**-1
perm = T(new_rel)
next = G_p.identity
for s in H.generator_product(perm, original=True):
next = next*T.invert(s)**-1
new_rel = new_rel*next
# continue coset enumeration
G_p = _factor_group_by_rels(G_p, [new_rel])
C_p.scan_and_fill(0, new_rel)
C_p = G_p.coset_enumeration([], strategy="coset_table",
draft=C_p, max_cosets=n, incomplete=True)
G._fp_presentation = simplify_presentation(G_p)
return G._fp_presentation
def _orbit(degree, generators, alpha, action='tuples'):
r"""Compute the orbit of alpha `\{g(\alpha) | g \in G\}` as a set.
The time complexity of the algorithm used here is `O(|Orb|*r)` where
`|Orb|` is the size of the orbit and ``r`` is the number of generators of
the group. For a more detailed analysis, see [1], p.78, [2], pp. 19-21.
Here alpha can be a single point, or a list of points.
If alpha is a single point, the ordinary orbit is computed.
if alpha is a list of points, there are three available options:
'union' - computes the union of the orbits of the points in the list
'tuples' - computes the orbit of the list interpreted as an ordered
tuple under the group action ( i.e., g((1, 2, 3)) = (g(1), g(2), g(3)) )
'sets' - computes the orbit of the list interpreted as a sets
Examples
========
>>> from sympy.combinatorics import Permutation
>>> from sympy.combinatorics.perm_groups import PermutationGroup, _orbit
>>> a = Permutation([1, 2, 0, 4, 5, 6, 3])
>>> G = PermutationGroup([a])
>>> _orbit(G.degree, G.generators, 0)
{0, 1, 2}
>>> _orbit(G.degree, G.generators, [0, 4], 'union')
{0, 1, 2, 3, 4, 5, 6}
See Also
========
orbit, orbit_transversal
"""
if not hasattr(alpha, '__getitem__'):
alpha = [alpha]
gens = [x._array_form for x in generators]
if len(alpha) == 1 or action == 'union':
orb = alpha
used = [False]*degree
for el in alpha:
used[el] = True
for b in orb:
for gen in gens:
temp = gen[b]
if used[temp] == False:
orb.append(temp)
used[temp] = True
return set(orb)
elif action == 'tuples':
alpha = tuple(alpha)
orb = [alpha]
used = {alpha}
for b in orb:
for gen in gens:
temp = tuple([gen[x] for x in b])
if temp not in used:
orb.append(temp)
used.add(temp)
return set(orb)
elif action == 'sets':
alpha = frozenset(alpha)
orb = [alpha]
used = {alpha}
for b in orb:
for gen in gens:
temp = frozenset([gen[x] for x in b])
if temp not in used:
orb.append(temp)
used.add(temp)
return {tuple(x) for x in orb}
def _orbits(degree, generators):
"""Compute the orbits of G.
If ``rep=False`` it returns a list of sets else it returns a list of
representatives of the orbits
Examples
========
>>> from sympy.combinatorics.permutations import Permutation
>>> from sympy.combinatorics.perm_groups import PermutationGroup, _orbits
>>> a = Permutation([0, 2, 1])
>>> b = Permutation([1, 0, 2])
>>> _orbits(a.size, [a, b])
[{0, 1, 2}]
"""
orbs = []
sorted_I = list(range(degree))
I = set(sorted_I)
while I:
i = sorted_I[0]
orb = _orbit(degree, generators, i)
orbs.append(orb)
# remove all indices that are in this orbit
I -= orb
sorted_I = [i for i in sorted_I if i not in orb]
return orbs
def _orbit_transversal(degree, generators, alpha, pairs, af=False, slp=False):
r"""Computes a transversal for the orbit of ``alpha`` as a set.
generators generators of the group ``G``
For a permutation group ``G``, a transversal for the orbit
`Orb = \{g(\alpha) | g \in G\}` is a set
`\{g_\beta | g_\beta(\alpha) = \beta\}` for `\beta \in Orb`.
Note that there may be more than one possible transversal.
If ``pairs`` is set to ``True``, it returns the list of pairs
`(\beta, g_\beta)`. For a proof of correctness, see [1], p.79
if ``af`` is ``True``, the transversal elements are given in
array form.
If `slp` is `True`, a dictionary `{beta: slp_beta}` is returned
for `\beta \in Orb` where `slp_beta` is a list of indices of the
generators in `generators` s.t. if `slp_beta = [i_1 ... i_n]`
`g_\beta = generators[i_n]*...*generators[i_1]`.
Examples
========
>>> from sympy.combinatorics import Permutation
>>> Permutation.print_cyclic = True
>>> from sympy.combinatorics.named_groups import DihedralGroup
>>> from sympy.combinatorics.perm_groups import _orbit_transversal
>>> G = DihedralGroup(6)
>>> _orbit_transversal(G.degree, G.generators, 0, False)
[(5), (0 1 2 3 4 5), (0 5)(1 4)(2 3), (0 2 4)(1 3 5), (5)(0 4)(1 3), (0 3)(1 4)(2 5)]
"""
tr = [(alpha, list(range(degree)))]
slp_dict = {alpha: []}
used = [False]*degree
used[alpha] = True
gens = [x._array_form for x in generators]
for x, px in tr:
px_slp = slp_dict[x]
for gen in gens:
temp = gen[x]
if used[temp] == False:
slp_dict[temp] = [gens.index(gen)] + px_slp
tr.append((temp, _af_rmul(gen, px)))
used[temp] = True
if pairs:
if not af:
tr = [(x, _af_new(y)) for x, y in tr]
if not slp:
return tr
return tr, slp_dict
if af:
tr = [y for _, y in tr]
if not slp:
return tr
return tr, slp_dict
tr = [_af_new(y) for _, y in tr]
if not slp:
return tr
return tr, slp_dict
def _stabilizer(degree, generators, alpha):
r"""Return the stabilizer subgroup of ``alpha``.
The stabilizer of `\alpha` is the group `G_\alpha =
\{g \in G | g(\alpha) = \alpha\}`.
For a proof of correctness, see [1], p.79.
degree : degree of G
generators : generators of G
Examples
========
>>> from sympy.combinatorics import Permutation
>>> Permutation.print_cyclic = True
>>> from sympy.combinatorics.perm_groups import _stabilizer
>>> from sympy.combinatorics.named_groups import DihedralGroup
>>> G = DihedralGroup(6)
>>> _stabilizer(G.degree, G.generators, 5)
[(5)(0 4)(1 3), (5)]
See Also
========
orbit
"""
orb = [alpha]
table = {alpha: list(range(degree))}
table_inv = {alpha: list(range(degree))}
used = [False]*degree
used[alpha] = True
gens = [x._array_form for x in generators]
stab_gens = []
for b in orb:
for gen in gens:
temp = gen[b]
if used[temp] is False:
gen_temp = _af_rmul(gen, table[b])
orb.append(temp)
table[temp] = gen_temp
table_inv[temp] = _af_invert(gen_temp)
used[temp] = True
else:
schreier_gen = _af_rmuln(table_inv[temp], gen, table[b])
if schreier_gen not in stab_gens:
stab_gens.append(schreier_gen)
return [_af_new(x) for x in stab_gens]
PermGroup = PermutationGroup
|
be187428e98d5894ea3b66a184e1f1611c765142c86c429fc18d2cc51617f5d3
|
from __future__ import print_function, division
from sympy.combinatorics.permutations import Permutation
from sympy.core.compatibility import range
from sympy.core.symbol import symbols
from sympy.matrices import Matrix
from sympy.utilities.iterables import variations, rotate_left
def symmetric(n):
"""
Generates the symmetric group of order n, Sn.
Examples
========
>>> from sympy.combinatorics.permutations import Permutation
>>> Permutation.print_cyclic = True
>>> from sympy.combinatorics.generators import symmetric
>>> list(symmetric(3))
[(2), (1 2), (2)(0 1), (0 1 2), (0 2 1), (0 2)]
"""
for perm in variations(list(range(n)), n):
yield Permutation(perm)
def cyclic(n):
"""
Generates the cyclic group of order n, Cn.
Examples
========
>>> from sympy.combinatorics.permutations import Permutation
>>> Permutation.print_cyclic = True
>>> from sympy.combinatorics.generators import cyclic
>>> list(cyclic(5))
[(4), (0 1 2 3 4), (0 2 4 1 3),
(0 3 1 4 2), (0 4 3 2 1)]
See Also
========
dihedral
"""
gen = list(range(n))
for i in range(n):
yield Permutation(gen)
gen = rotate_left(gen, 1)
def alternating(n):
"""
Generates the alternating group of order n, An.
Examples
========
>>> from sympy.combinatorics.permutations import Permutation
>>> Permutation.print_cyclic = True
>>> from sympy.combinatorics.generators import alternating
>>> list(alternating(3))
[(2), (0 1 2), (0 2 1)]
"""
for perm in variations(list(range(n)), n):
p = Permutation(perm)
if p.is_even:
yield p
def dihedral(n):
"""
Generates the dihedral group of order 2n, Dn.
The result is given as a subgroup of Sn, except for the special cases n=1
(the group S2) and n=2 (the Klein 4-group) where that's not possible
and embeddings in S2 and S4 respectively are given.
Examples
========
>>> from sympy.combinatorics.permutations import Permutation
>>> Permutation.print_cyclic = True
>>> from sympy.combinatorics.generators import dihedral
>>> list(dihedral(3))
[(2), (0 2), (0 1 2), (1 2), (0 2 1), (2)(0 1)]
See Also
========
cyclic
"""
if n == 1:
yield Permutation([0, 1])
yield Permutation([1, 0])
elif n == 2:
yield Permutation([0, 1, 2, 3])
yield Permutation([1, 0, 3, 2])
yield Permutation([2, 3, 0, 1])
yield Permutation([3, 2, 1, 0])
else:
gen = list(range(n))
for i in range(n):
yield Permutation(gen)
yield Permutation(gen[::-1])
gen = rotate_left(gen, 1)
def rubik_cube_generators():
"""Return the permutations of the 3x3 Rubik's cube, see
http://www.gap-system.org/Doc/Examples/rubik.html
"""
a = [
[(1, 3, 8, 6), (2, 5, 7, 4), (9, 33, 25, 17), (10, 34, 26, 18),
(11, 35, 27, 19)],
[(9, 11, 16, 14), (10, 13, 15, 12), (1, 17, 41, 40), (4, 20, 44, 37),
(6, 22, 46, 35)],
[(17, 19, 24, 22), (18, 21, 23, 20), (6, 25, 43, 16), (7, 28, 42, 13),
(8, 30, 41, 11)],
[(25, 27, 32, 30), (26, 29, 31, 28), (3, 38, 43, 19), (5, 36, 45, 21),
(8, 33, 48, 24)],
[(33, 35, 40, 38), (34, 37, 39, 36), (3, 9, 46, 32), (2, 12, 47, 29),
(1, 14, 48, 27)],
[(41, 43, 48, 46), (42, 45, 47, 44), (14, 22, 30, 38),
(15, 23, 31, 39), (16, 24, 32, 40)]
]
return [Permutation([[i - 1 for i in xi] for xi in x], size=48) for x in a]
def rubik(n):
"""Return permutations for an nxn Rubik's cube.
Permutations returned are for rotation of each of the slice
from the face up to the last face for each of the 3 sides (in this order):
front, right and bottom. Hence, the first n - 1 permutations are for the
slices from the front.
"""
if n < 2:
raise ValueError('dimension of cube must be > 1')
# 1-based reference to rows and columns in Matrix
def getr(f, i):
return faces[f].col(n - i)
def getl(f, i):
return faces[f].col(i - 1)
def getu(f, i):
return faces[f].row(i - 1)
def getd(f, i):
return faces[f].row(n - i)
def setr(f, i, s):
faces[f][:, n - i] = Matrix(n, 1, s)
def setl(f, i, s):
faces[f][:, i - 1] = Matrix(n, 1, s)
def setu(f, i, s):
faces[f][i - 1, :] = Matrix(1, n, s)
def setd(f, i, s):
faces[f][n - i, :] = Matrix(1, n, s)
# motion of a single face
def cw(F, r=1):
for _ in range(r):
face = faces[F]
rv = []
for c in range(n):
for r in range(n - 1, -1, -1):
rv.append(face[r, c])
faces[F] = Matrix(n, n, rv)
def ccw(F):
cw(F, 3)
# motion of plane i from the F side;
# fcw(0) moves the F face, fcw(1) moves the plane
# just behind the front face, etc...
def fcw(i, r=1):
for _ in range(r):
if i == 0:
cw(F)
i += 1
temp = getr(L, i)
setr(L, i, list((getu(D, i))))
setu(D, i, list(reversed(getl(R, i))))
setl(R, i, list((getd(U, i))))
setd(U, i, list(reversed(temp)))
i -= 1
def fccw(i):
fcw(i, 3)
# motion of the entire cube from the F side
def FCW(r=1):
for _ in range(r):
cw(F)
ccw(B)
cw(U)
t = faces[U]
cw(L)
faces[U] = faces[L]
cw(D)
faces[L] = faces[D]
cw(R)
faces[D] = faces[R]
faces[R] = t
def FCCW():
FCW(3)
# motion of the entire cube from the U side
def UCW(r=1):
for _ in range(r):
cw(U)
ccw(D)
t = faces[F]
faces[F] = faces[R]
faces[R] = faces[B]
faces[B] = faces[L]
faces[L] = t
def UCCW():
UCW(3)
# defining the permutations for the cube
U, F, R, B, L, D = names = symbols('U, F, R, B, L, D')
# the faces are represented by nxn matrices
faces = {}
count = 0
for fi in range(6):
f = []
for a in range(n**2):
f.append(count)
count += 1
faces[names[fi]] = Matrix(n, n, f)
# this will either return the value of the current permutation
# (show != 1) or else append the permutation to the group, g
def perm(show=0):
# add perm to the list of perms
p = []
for f in names:
p.extend(faces[f])
if show:
return p
g.append(Permutation(p))
g = [] # container for the group's permutations
I = list(range(6*n**2)) # the identity permutation used for checking
# define permutations corresponding to cw rotations of the planes
# up TO the last plane from that direction; by not including the
# last plane, the orientation of the cube is maintained.
# F slices
for i in range(n - 1):
fcw(i)
perm()
fccw(i) # restore
assert perm(1) == I
# R slices
# bring R to front
UCW()
for i in range(n - 1):
fcw(i)
# put it back in place
UCCW()
# record
perm()
# restore
# bring face to front
UCW()
fccw(i)
# restore
UCCW()
assert perm(1) == I
# D slices
# bring up bottom
FCW()
UCCW()
FCCW()
for i in range(n - 1):
# turn strip
fcw(i)
# put bottom back on the bottom
FCW()
UCW()
FCCW()
# record
perm()
# restore
# bring up bottom
FCW()
UCCW()
FCCW()
# turn strip
fccw(i)
# put bottom back on the bottom
FCW()
UCW()
FCCW()
assert perm(1) == I
return g
|
01b21f4f5c46ccb9d34d4e629bc877466da506707614bbb06ea0f6cb2bbbe21f
|
from __future__ import print_function, division
from sympy.core import Basic
from sympy.core.compatibility import range
import random
class GrayCode(Basic):
"""
A Gray code is essentially a Hamiltonian walk on
a n-dimensional cube with edge length of one.
The vertices of the cube are represented by vectors
whose values are binary. The Hamilton walk visits
each vertex exactly once. The Gray code for a 3d
cube is ['000','100','110','010','011','111','101',
'001'].
A Gray code solves the problem of sequentially
generating all possible subsets of n objects in such
a way that each subset is obtained from the previous
one by either deleting or adding a single object.
In the above example, 1 indicates that the object is
present, and 0 indicates that its absent.
Gray codes have applications in statistics as well when
we want to compute various statistics related to subsets
in an efficient manner.
Examples
========
>>> from sympy.combinatorics.graycode import GrayCode
>>> a = GrayCode(3)
>>> list(a.generate_gray())
['000', '001', '011', '010', '110', '111', '101', '100']
>>> a = GrayCode(4)
>>> list(a.generate_gray())
['0000', '0001', '0011', '0010', '0110', '0111', '0101', '0100', \
'1100', '1101', '1111', '1110', '1010', '1011', '1001', '1000']
References
==========
.. [1] Nijenhuis,A. and Wilf,H.S.(1978).
Combinatorial Algorithms. Academic Press.
.. [2] Knuth, D. (2011). The Art of Computer Programming, Vol 4
Addison Wesley
"""
_skip = False
_current = 0
_rank = None
def __new__(cls, n, *args, **kw_args):
"""
Default constructor.
It takes a single argument ``n`` which gives the dimension of the Gray
code. The starting Gray code string (``start``) or the starting ``rank``
may also be given; the default is to start at rank = 0 ('0...0').
Examples
========
>>> from sympy.combinatorics.graycode import GrayCode
>>> a = GrayCode(3)
>>> a
GrayCode(3)
>>> a.n
3
>>> a = GrayCode(3, start='100')
>>> a.current
'100'
>>> a = GrayCode(4, rank=4)
>>> a.current
'0110'
>>> a.rank
4
"""
if n < 1 or int(n) != n:
raise ValueError(
'Gray code dimension must be a positive integer, not %i' % n)
n = int(n)
args = (n,) + args
obj = Basic.__new__(cls, *args)
if 'start' in kw_args:
obj._current = kw_args["start"]
if len(obj._current) > n:
raise ValueError('Gray code start has length %i but '
'should not be greater than %i' % (len(obj._current), n))
elif 'rank' in kw_args:
if int(kw_args["rank"]) != kw_args["rank"]:
raise ValueError('Gray code rank must be a positive integer, '
'not %i' % kw_args["rank"])
obj._rank = int(kw_args["rank"]) % obj.selections
obj._current = obj.unrank(n, obj._rank)
return obj
def next(self, delta=1):
"""
Returns the Gray code a distance ``delta`` (default = 1) from the
current value in canonical order.
Examples
========
>>> from sympy.combinatorics.graycode import GrayCode
>>> a = GrayCode(3, start='110')
>>> a.next().current
'111'
>>> a.next(-1).current
'010'
"""
return GrayCode(self.n, rank=(self.rank + delta) % self.selections)
@property
def selections(self):
"""
Returns the number of bit vectors in the Gray code.
Examples
========
>>> from sympy.combinatorics.graycode import GrayCode
>>> a = GrayCode(3)
>>> a.selections
8
"""
return 2**self.n
@property
def n(self):
"""
Returns the dimension of the Gray code.
Examples
========
>>> from sympy.combinatorics.graycode import GrayCode
>>> a = GrayCode(5)
>>> a.n
5
"""
return self.args[0]
def generate_gray(self, **hints):
"""
Generates the sequence of bit vectors of a Gray Code.
Examples
========
>>> from sympy.combinatorics.graycode import GrayCode
>>> a = GrayCode(3)
>>> list(a.generate_gray())
['000', '001', '011', '010', '110', '111', '101', '100']
>>> list(a.generate_gray(start='011'))
['011', '010', '110', '111', '101', '100']
>>> list(a.generate_gray(rank=4))
['110', '111', '101', '100']
See Also
========
skip
References
==========
.. [1] Knuth, D. (2011). The Art of Computer Programming,
Vol 4, Addison Wesley
"""
bits = self.n
start = None
if "start" in hints:
start = hints["start"]
elif "rank" in hints:
start = GrayCode.unrank(self.n, hints["rank"])
if start is not None:
self._current = start
current = self.current
graycode_bin = gray_to_bin(current)
if len(graycode_bin) > self.n:
raise ValueError('Gray code start has length %i but should '
'not be greater than %i' % (len(graycode_bin), bits))
self._current = int(current, 2)
graycode_int = int(''.join(graycode_bin), 2)
for i in range(graycode_int, 1 << bits):
if self._skip:
self._skip = False
else:
yield self.current
bbtc = (i ^ (i + 1))
gbtc = (bbtc ^ (bbtc >> 1))
self._current = (self._current ^ gbtc)
self._current = 0
def skip(self):
"""
Skips the bit generation.
Examples
========
>>> from sympy.combinatorics.graycode import GrayCode
>>> a = GrayCode(3)
>>> for i in a.generate_gray():
... if i == '010':
... a.skip()
... print(i)
...
000
001
011
010
111
101
100
See Also
========
generate_gray
"""
self._skip = True
@property
def rank(self):
"""
Ranks the Gray code.
A ranking algorithm determines the position (or rank)
of a combinatorial object among all the objects w.r.t.
a given order. For example, the 4 bit binary reflected
Gray code (BRGC) '0101' has a rank of 6 as it appears in
the 6th position in the canonical ordering of the family
of 4 bit Gray codes.
Examples
========
>>> from sympy.combinatorics.graycode import GrayCode
>>> a = GrayCode(3)
>>> list(a.generate_gray())
['000', '001', '011', '010', '110', '111', '101', '100']
>>> GrayCode(3, start='100').rank
7
>>> GrayCode(3, rank=7).current
'100'
See Also
========
unrank
References
==========
.. [1] http://statweb.stanford.edu/~susan/courses/s208/node12.html
"""
if self._rank is None:
self._rank = int(gray_to_bin(self.current), 2)
return self._rank
@property
def current(self):
"""
Returns the currently referenced Gray code as a bit string.
Examples
========
>>> from sympy.combinatorics.graycode import GrayCode
>>> GrayCode(3, start='100').current
'100'
"""
rv = self._current or '0'
if type(rv) is not str:
rv = bin(rv)[2:]
return rv.rjust(self.n, '0')
@classmethod
def unrank(self, n, rank):
"""
Unranks an n-bit sized Gray code of rank k. This method exists
so that a derivative GrayCode class can define its own code of
a given rank.
The string here is generated in reverse order to allow for tail-call
optimization.
Examples
========
>>> from sympy.combinatorics.graycode import GrayCode
>>> GrayCode(5, rank=3).current
'00010'
>>> GrayCode.unrank(5, 3)
'00010'
See Also
========
rank
"""
def _unrank(k, n):
if n == 1:
return str(k % 2)
m = 2**(n - 1)
if k < m:
return '0' + _unrank(k, n - 1)
return '1' + _unrank(m - (k % m) - 1, n - 1)
return _unrank(rank, n)
def random_bitstring(n):
"""
Generates a random bitlist of length n.
Examples
========
>>> from sympy.combinatorics.graycode import random_bitstring
>>> random_bitstring(3) # doctest: +SKIP
100
"""
return ''.join([random.choice('01') for i in range(n)])
def gray_to_bin(bin_list):
"""
Convert from Gray coding to binary coding.
We assume big endian encoding.
Examples
========
>>> from sympy.combinatorics.graycode import gray_to_bin
>>> gray_to_bin('100')
'111'
See Also
========
bin_to_gray
"""
b = [bin_list[0]]
for i in range(1, len(bin_list)):
b += str(int(b[i - 1] != bin_list[i]))
return ''.join(b)
def bin_to_gray(bin_list):
"""
Convert from binary coding to gray coding.
We assume big endian encoding.
Examples
========
>>> from sympy.combinatorics.graycode import bin_to_gray
>>> bin_to_gray('111')
'100'
See Also
========
gray_to_bin
"""
b = [bin_list[0]]
for i in range(1, len(bin_list)):
b += str(int(bin_list[i]) ^ int(bin_list[i - 1]))
return ''.join(b)
def get_subset_from_bitstring(super_set, bitstring):
"""
Gets the subset defined by the bitstring.
Examples
========
>>> from sympy.combinatorics.graycode import get_subset_from_bitstring
>>> get_subset_from_bitstring(['a', 'b', 'c', 'd'], '0011')
['c', 'd']
>>> get_subset_from_bitstring(['c', 'a', 'c', 'c'], '1100')
['c', 'a']
See Also
========
graycode_subsets
"""
if len(super_set) != len(bitstring):
raise ValueError("The sizes of the lists are not equal")
return [super_set[i] for i, j in enumerate(bitstring)
if bitstring[i] == '1']
def graycode_subsets(gray_code_set):
"""
Generates the subsets as enumerated by a Gray code.
Examples
========
>>> from sympy.combinatorics.graycode import graycode_subsets
>>> list(graycode_subsets(['a', 'b', 'c']))
[[], ['c'], ['b', 'c'], ['b'], ['a', 'b'], ['a', 'b', 'c'], \
['a', 'c'], ['a']]
>>> list(graycode_subsets(['a', 'b', 'c', 'c']))
[[], ['c'], ['c', 'c'], ['c'], ['b', 'c'], ['b', 'c', 'c'], \
['b', 'c'], ['b'], ['a', 'b'], ['a', 'b', 'c'], ['a', 'b', 'c', 'c'], \
['a', 'b', 'c'], ['a', 'c'], ['a', 'c', 'c'], ['a', 'c'], ['a']]
See Also
========
get_subset_from_bitstring
"""
for bitstring in list(GrayCode(len(gray_code_set)).generate_gray()):
yield get_subset_from_bitstring(gray_code_set, bitstring)
|
75f6ea32c86fa6b3f05e15807b02754eecb0a8cdbc819c872da5686dbdca35ef
|
from __future__ import print_function, division
from sympy.combinatorics.rewritingsystem_fsm import StateMachine
class RewritingSystem(object):
'''
A class implementing rewriting systems for `FpGroup`s.
References
==========
.. [1] Epstein, D., Holt, D. and Rees, S. (1991).
The use of Knuth-Bendix methods to solve the word problem in automatic groups.
Journal of Symbolic Computation, 12(4-5), pp.397-414.
.. [2] GAP's Manual on its KBMAG package
https://www.gap-system.org/Manuals/pkg/kbmag-1.5.3/doc/manual.pdf
'''
def __init__(self, group):
from collections import deque
self.group = group
self.alphabet = group.generators
self._is_confluent = None
# these values are taken from [2]
self.maxeqns = 32767 # max rules
self.tidyint = 100 # rules before tidying
# _max_exceeded is True if maxeqns is exceeded
# at any point
self._max_exceeded = False
# Reduction automaton
self.reduction_automaton = None
self._new_rules = {}
# dictionary of reductions
self.rules = {}
self.rules_cache = deque([], 50)
self._init_rules()
# All the transition symbols in the automaton
generators = list(self.alphabet)
generators += [gen**-1 for gen in generators]
# Create a finite state machine as an instance of the StateMachine object
self.reduction_automaton = StateMachine('Reduction automaton for '+ repr(self.group), generators)
self.construct_automaton()
def set_max(self, n):
'''
Set the maximum number of rules that can be defined
'''
if self._max_exceeded and n > self.maxeqns:
self._max_exceeded = False
self.maxeqns = n
return
@property
def is_confluent(self):
'''
Return `True` if the system is confluent
'''
if self._is_confluent is None:
self._is_confluent = self._check_confluence()
return self._is_confluent
def _init_rules(self):
identity = self.group.free_group.identity
for r in self.group.relators:
self.add_rule(r, identity)
self._remove_redundancies()
return
def _add_rule(self, r1, r2):
'''
Add the rule r1 -> r2 with no checking or further
deductions
'''
if len(self.rules) + 1 > self.maxeqns:
self._is_confluent = self._check_confluence()
self._max_exceeded = True
raise RuntimeError("Too many rules were defined.")
self.rules[r1] = r2
# Add the newly added rule to the `new_rules` dictionary.
if self.reduction_automaton:
self._new_rules[r1] = r2
def add_rule(self, w1, w2, check=False):
new_keys = set()
if w1 == w2:
return new_keys
if w1 < w2:
w1, w2 = w2, w1
if (w1, w2) in self.rules_cache:
return new_keys
self.rules_cache.append((w1, w2))
s1, s2 = w1, w2
# The following is the equivalent of checking
# s1 for overlaps with the implicit reductions
# {g*g**-1 -> <identity>} and {g**-1*g -> <identity>}
# for any generator g without installing the
# redundant rules that would result from processing
# the overlaps. See [1], Section 3 for details.
if len(s1) - len(s2) < 3:
if s1 not in self.rules:
new_keys.add(s1)
if not check:
self._add_rule(s1, s2)
if s2**-1 > s1**-1 and s2**-1 not in self.rules:
new_keys.add(s2**-1)
if not check:
self._add_rule(s2**-1, s1**-1)
# overlaps on the right
while len(s1) - len(s2) > -1:
g = s1[len(s1)-1]
s1 = s1.subword(0, len(s1)-1)
s2 = s2*g**-1
if len(s1) - len(s2) < 0:
if s2 not in self.rules:
if not check:
self._add_rule(s2, s1)
new_keys.add(s2)
elif len(s1) - len(s2) < 3:
new = self.add_rule(s1, s2, check)
new_keys.update(new)
# overlaps on the left
while len(w1) - len(w2) > -1:
g = w1[0]
w1 = w1.subword(1, len(w1))
w2 = g**-1*w2
if len(w1) - len(w2) < 0:
if w2 not in self.rules:
if not check:
self._add_rule(w2, w1)
new_keys.add(w2)
elif len(w1) - len(w2) < 3:
new = self.add_rule(w1, w2, check)
new_keys.update(new)
return new_keys
def _remove_redundancies(self, changes=False):
'''
Reduce left- and right-hand sides of reduction rules
and remove redundant equations (i.e. those for which
lhs == rhs). If `changes` is `True`, return a set
containing the removed keys and a set containing the
added keys
'''
removed = set()
added = set()
rules = self.rules.copy()
for r in rules:
v = self.reduce(r, exclude=r)
w = self.reduce(rules[r])
if v != r:
del self.rules[r]
removed.add(r)
if v > w:
added.add(v)
self.rules[v] = w
elif v < w:
added.add(w)
self.rules[w] = v
else:
self.rules[v] = w
if changes:
return removed, added
return
def make_confluent(self, check=False):
'''
Try to make the system confluent using the Knuth-Bendix
completion algorithm
'''
if self._max_exceeded:
return self._is_confluent
lhs = list(self.rules.keys())
def _overlaps(r1, r2):
len1 = len(r1)
len2 = len(r2)
result = []
for j in range(1, len1 + len2):
if (r1.subword(len1 - j, len1 + len2 - j, strict=False)
== r2.subword(j - len1, j, strict=False)):
a = r1.subword(0, len1-j, strict=False)
a = a*r2.subword(0, j-len1, strict=False)
b = r2.subword(j-len1, j, strict=False)
c = r2.subword(j, len2, strict=False)
c = c*r1.subword(len1 + len2 - j, len1, strict=False)
result.append(a*b*c)
return result
def _process_overlap(w, r1, r2, check):
s = w.eliminate_word(r1, self.rules[r1])
s = self.reduce(s)
t = w.eliminate_word(r2, self.rules[r2])
t = self.reduce(t)
if s != t:
if check:
# system not confluent
return [0]
try:
new_keys = self.add_rule(t, s, check)
return new_keys
except RuntimeError:
return False
return
added = 0
i = 0
while i < len(lhs):
r1 = lhs[i]
i += 1
# j could be i+1 to not
# check each pair twice but lhs
# is extended in the loop and the new
# elements have to be checked with the
# preceding ones. there is probably a better way
# to handle this
j = 0
while j < len(lhs):
r2 = lhs[j]
j += 1
if r1 == r2:
continue
overlaps = _overlaps(r1, r2)
overlaps.extend(_overlaps(r1**-1, r2))
if not overlaps:
continue
for w in overlaps:
new_keys = _process_overlap(w, r1, r2, check)
if new_keys:
if check:
return False
lhs.extend(new_keys)
added += len(new_keys)
elif new_keys == False:
# too many rules were added so the process
# couldn't complete
return self._is_confluent
if added > self.tidyint and not check:
# tidy up
r, a = self._remove_redundancies(changes=True)
added = 0
if r:
# reset i since some elements were removed
i = min([lhs.index(s) for s in r])
lhs = [l for l in lhs if l not in r]
lhs.extend(a)
if r1 in r:
# r1 was removed as redundant
break
self._is_confluent = True
if not check:
self._remove_redundancies()
return True
def _check_confluence(self):
return self.make_confluent(check=True)
def reduce(self, word, exclude=None):
'''
Apply reduction rules to `word` excluding the reduction rule
for the lhs equal to `exclude`
'''
rules = {r: self.rules[r] for r in self.rules if r != exclude}
# the following is essentially `eliminate_words()` code from the
# `FreeGroupElement` class, the only difference being the first
# "if" statement
again = True
new = word
while again:
again = False
for r in rules:
prev = new
if rules[r]**-1 > r**-1:
new = new.eliminate_word(r, rules[r], _all=True, inverse=False)
else:
new = new.eliminate_word(r, rules[r], _all=True)
if new != prev:
again = True
return new
def _compute_inverse_rules(self, rules):
'''
Compute the inverse rules for a given set of rules.
The inverse rules are used in the automaton for word reduction.
Arguments:
rules (dictionary): Rules for which the inverse rules are to computed.
Returns:
Dictionary of inverse_rules.
'''
inverse_rules = {}
for r in rules:
rule_key_inverse = r**-1
rule_value_inverse = (rules[r])**-1
if (rule_value_inverse < rule_key_inverse):
inverse_rules[rule_key_inverse] = rule_value_inverse
else:
inverse_rules[rule_value_inverse] = rule_key_inverse
return inverse_rules
def construct_automaton(self):
'''
Construct the automaton based on the set of reduction rules of the system.
Automata Design:
The accept states of the automaton are the proper prefixes of the left hand side of the rules.
The complete left hand side of the rules are the dead states of the automaton.
'''
self._add_to_automaton(self.rules)
def _add_to_automaton(self, rules):
'''
Add new states and transitions to the automaton.
Summary:
States corresponding to the new rules added to the system are computed and added to the automaton.
Transitions in the previously added states are also modified if necessary.
Arguments:
rules (dictionary) -- Dictionary of the newly added rules.
'''
# Automaton variables
automaton_alphabet = []
proper_prefixes = {}
# compute the inverses of all the new rules added
all_rules = rules
inverse_rules = self._compute_inverse_rules(all_rules)
all_rules.update(inverse_rules)
# Keep track of the accept_states.
accept_states = []
for rule in all_rules:
# The symbols present in the new rules are the symbols to be verified at each state.
# computes the automaton_alphabet, as the transitions solely depend upon the new states.
automaton_alphabet += rule.letter_form_elm
# Compute the proper prefixes for every rule.
proper_prefixes[rule] = []
letter_word_array = [s for s in rule.letter_form_elm]
len_letter_word_array = len(letter_word_array)
for i in range (1, len_letter_word_array):
letter_word_array[i] = letter_word_array[i-1]*letter_word_array[i]
# Add accept states.
elem = letter_word_array[i-1]
if not elem in self.reduction_automaton.states:
self.reduction_automaton.add_state(elem, state_type='a')
accept_states.append(elem)
proper_prefixes[rule] = letter_word_array
# Check for overlaps between dead and accept states.
if rule in accept_states:
self.reduction_automaton.states[rule].state_type = 'd'
self.reduction_automaton.states[rule].rh_rule = all_rules[rule]
accept_states.remove(rule)
# Add dead states
if not rule in self.reduction_automaton.states:
self.reduction_automaton.add_state(rule, state_type='d', rh_rule=all_rules[rule])
automaton_alphabet = set(automaton_alphabet)
# Add new transitions for every state.
for state in self.reduction_automaton.states:
current_state_name = state
current_state_type = self.reduction_automaton.states[state].state_type
# Transitions will be modified only when suffixes of the current_state
# belongs to the proper_prefixes of the new rules.
# The rest are ignored if they cannot lead to a dead state after a finite number of transisitons.
if current_state_type == 's':
for letter in automaton_alphabet:
if letter in self.reduction_automaton.states:
self.reduction_automaton.states[state].add_transition(letter, letter)
else:
self.reduction_automaton.states[state].add_transition(letter, current_state_name)
elif current_state_type == 'a':
# Check if the transition to any new state in posible.
for letter in automaton_alphabet:
_next = current_state_name*letter
while len(_next) and _next not in self.reduction_automaton.states:
_next = _next.subword(1, len(_next))
if not len(_next):
_next = 'start'
self.reduction_automaton.states[state].add_transition(letter, _next)
# Add transitions for new states. All symbols used in the automaton are considered here.
# Ignore this if `reduction_automaton.automaton_alphabet` = `automaton_alphabet`.
if len(self.reduction_automaton.automaton_alphabet) != len(automaton_alphabet):
for state in accept_states:
current_state_name = state
for letter in self.reduction_automaton.automaton_alphabet:
_next = current_state_name*letter
while len(_next) and _next not in self.reduction_automaton.states:
_next = _next.subword(1, len(_next))
if not len(_next):
_next = 'start'
self.reduction_automaton.states[state].add_transition(letter, _next)
def reduce_using_automaton(self, word):
'''
Reduce a word using an automaton.
Summary:
All the symbols of the word are stored in an array and are given as the input to the automaton.
If the automaton reaches a dead state that subword is replaced and the automaton is run from the beginning.
The complete word has to be replaced when the word is read and the automaton reaches a dead state.
So, this process is repeated until the word is read completely and the automaton reaches the accept state.
Arguments:
word (instance of FreeGroupElement) -- Word that needs to be reduced.
'''
# Modify the automaton if new rules are found.
if self._new_rules:
self._add_to_automaton(self._new_rules)
self._new_rules = {}
flag = 1
while flag:
flag = 0
current_state = self.reduction_automaton.states['start']
word_array = [s for s in word.letter_form_elm]
for i in range (0, len(word_array)):
next_state_name = current_state.transitions[word_array[i]]
next_state = self.reduction_automaton.states[next_state_name]
if next_state.state_type == 'd':
subst = next_state.rh_rule
word = word.substituted_word(i - len(next_state_name) + 1, i+1, subst)
flag = 1
break
current_state = next_state
return word
|
2d2beda90dcaee27e6427bbe3d5fef15bcecf29a071e9d219060a3db1d07b1ad
|
from __future__ import print_function, division
import random
from collections import defaultdict
from sympy.core import Basic
from sympy.core.compatibility import is_sequence, reduce, range, as_int
from sympy.matrices import zeros
from sympy.polys.polytools import lcm
from sympy.utilities.iterables import (flatten, has_variety, minlex,
has_dups, runs)
from mpmath.libmp.libintmath import ifac
def _af_rmul(a, b):
"""
Return the product b*a; input and output are array forms. The ith value
is a[b[i]].
Examples
========
>>> from sympy.combinatorics.permutations import _af_rmul, Permutation
>>> Permutation.print_cyclic = False
>>> a, b = [1, 0, 2], [0, 2, 1]
>>> _af_rmul(a, b)
[1, 2, 0]
>>> [a[b[i]] for i in range(3)]
[1, 2, 0]
This handles the operands in reverse order compared to the ``*`` operator:
>>> a = Permutation(a)
>>> b = Permutation(b)
>>> list(a*b)
[2, 0, 1]
>>> [b(a(i)) for i in range(3)]
[2, 0, 1]
See Also
========
rmul, _af_rmuln
"""
return [a[i] for i in b]
def _af_rmuln(*abc):
"""
Given [a, b, c, ...] return the product of ...*c*b*a using array forms.
The ith value is a[b[c[i]]].
Examples
========
>>> from sympy.combinatorics.permutations import _af_rmul, Permutation
>>> Permutation.print_cyclic = False
>>> a, b = [1, 0, 2], [0, 2, 1]
>>> _af_rmul(a, b)
[1, 2, 0]
>>> [a[b[i]] for i in range(3)]
[1, 2, 0]
This handles the operands in reverse order compared to the ``*`` operator:
>>> a = Permutation(a); b = Permutation(b)
>>> list(a*b)
[2, 0, 1]
>>> [b(a(i)) for i in range(3)]
[2, 0, 1]
See Also
========
rmul, _af_rmul
"""
a = abc
m = len(a)
if m == 3:
p0, p1, p2 = a
return [p0[p1[i]] for i in p2]
if m == 4:
p0, p1, p2, p3 = a
return [p0[p1[p2[i]]] for i in p3]
if m == 5:
p0, p1, p2, p3, p4 = a
return [p0[p1[p2[p3[i]]]] for i in p4]
if m == 6:
p0, p1, p2, p3, p4, p5 = a
return [p0[p1[p2[p3[p4[i]]]]] for i in p5]
if m == 7:
p0, p1, p2, p3, p4, p5, p6 = a
return [p0[p1[p2[p3[p4[p5[i]]]]]] for i in p6]
if m == 8:
p0, p1, p2, p3, p4, p5, p6, p7 = a
return [p0[p1[p2[p3[p4[p5[p6[i]]]]]]] for i in p7]
if m == 1:
return a[0][:]
if m == 2:
a, b = a
return [a[i] for i in b]
if m == 0:
raise ValueError("String must not be empty")
p0 = _af_rmuln(*a[:m//2])
p1 = _af_rmuln(*a[m//2:])
return [p0[i] for i in p1]
def _af_parity(pi):
"""
Computes the parity of a permutation in array form.
The parity of a permutation reflects the parity of the
number of inversions in the permutation, i.e., the
number of pairs of x and y such that x > y but p[x] < p[y].
Examples
========
>>> from sympy.combinatorics.permutations import _af_parity
>>> _af_parity([0, 1, 2, 3])
0
>>> _af_parity([3, 2, 0, 1])
1
See Also
========
Permutation
"""
n = len(pi)
a = [0] * n
c = 0
for j in range(n):
if a[j] == 0:
c += 1
a[j] = 1
i = j
while pi[i] != j:
i = pi[i]
a[i] = 1
return (n - c) % 2
def _af_invert(a):
"""
Finds the inverse, ~A, of a permutation, A, given in array form.
Examples
========
>>> from sympy.combinatorics.permutations import _af_invert, _af_rmul
>>> A = [1, 2, 0, 3]
>>> _af_invert(A)
[2, 0, 1, 3]
>>> _af_rmul(_, A)
[0, 1, 2, 3]
See Also
========
Permutation, __invert__
"""
inv_form = [0] * len(a)
for i, ai in enumerate(a):
inv_form[ai] = i
return inv_form
def _af_pow(a, n):
"""
Routine for finding powers of a permutation.
Examples
========
>>> from sympy.combinatorics.permutations import Permutation, _af_pow
>>> Permutation.print_cyclic = False
>>> p = Permutation([2, 0, 3, 1])
>>> p.order()
4
>>> _af_pow(p._array_form, 4)
[0, 1, 2, 3]
"""
if n == 0:
return list(range(len(a)))
if n < 0:
return _af_pow(_af_invert(a), -n)
if n == 1:
return a[:]
elif n == 2:
b = [a[i] for i in a]
elif n == 3:
b = [a[a[i]] for i in a]
elif n == 4:
b = [a[a[a[i]]] for i in a]
else:
# use binary multiplication
b = list(range(len(a)))
while 1:
if n & 1:
b = [b[i] for i in a]
n -= 1
if not n:
break
if n % 4 == 0:
a = [a[a[a[i]]] for i in a]
n = n // 4
elif n % 2 == 0:
a = [a[i] for i in a]
n = n // 2
return b
def _af_commutes_with(a, b):
"""
Checks if the two permutations with array forms
given by ``a`` and ``b`` commute.
Examples
========
>>> from sympy.combinatorics.permutations import _af_commutes_with
>>> _af_commutes_with([1, 2, 0], [0, 2, 1])
False
See Also
========
Permutation, commutes_with
"""
return not any(a[b[i]] != b[a[i]] for i in range(len(a) - 1))
class Cycle(dict):
"""
Wrapper around dict which provides the functionality of a disjoint cycle.
A cycle shows the rule to use to move subsets of elements to obtain
a permutation. The Cycle class is more flexible than Permutation in
that 1) all elements need not be present in order to investigate how
multiple cycles act in sequence and 2) it can contain singletons:
>>> from sympy.combinatorics.permutations import Perm, Cycle
A Cycle will automatically parse a cycle given as a tuple on the rhs:
>>> Cycle(1, 2)(2, 3)
(1 3 2)
The identity cycle, Cycle(), can be used to start a product:
>>> Cycle()(1, 2)(2, 3)
(1 3 2)
The array form of a Cycle can be obtained by calling the list
method (or passing it to the list function) and all elements from
0 will be shown:
>>> a = Cycle(1, 2)
>>> a.list()
[0, 2, 1]
>>> list(a)
[0, 2, 1]
If a larger (or smaller) range is desired use the list method and
provide the desired size -- but the Cycle cannot be truncated to
a size smaller than the largest element that is out of place:
>>> b = Cycle(2, 4)(1, 2)(3, 1, 4)(1, 3)
>>> b.list()
[0, 2, 1, 3, 4]
>>> b.list(b.size + 1)
[0, 2, 1, 3, 4, 5]
>>> b.list(-1)
[0, 2, 1]
Singletons are not shown when printing with one exception: the largest
element is always shown -- as a singleton if necessary:
>>> Cycle(1, 4, 10)(4, 5)
(1 5 4 10)
>>> Cycle(1, 2)(4)(5)(10)
(1 2)(10)
The array form can be used to instantiate a Permutation so other
properties of the permutation can be investigated:
>>> Perm(Cycle(1, 2)(3, 4).list()).transpositions()
[(1, 2), (3, 4)]
Notes
=====
The underlying structure of the Cycle is a dictionary and although
the __iter__ method has been redefined to give the array form of the
cycle, the underlying dictionary items are still available with the
such methods as items():
>>> list(Cycle(1, 2).items())
[(1, 2), (2, 1)]
See Also
========
Permutation
"""
def __missing__(self, arg):
"""Enter arg into dictionary and return arg."""
arg = as_int(arg)
self[arg] = arg
return arg
def __iter__(self):
for i in self.list():
yield i
def __call__(self, *other):
"""Return product of cycles processed from R to L.
Examples
========
>>> from sympy.combinatorics.permutations import Cycle as C
>>> from sympy.combinatorics.permutations import Permutation as Perm
>>> C(1, 2)(2, 3)
(1 3 2)
An instance of a Cycle will automatically parse list-like
objects and Permutations that are on the right. It is more
flexible than the Permutation in that all elements need not
be present:
>>> a = C(1, 2)
>>> a(2, 3)
(1 3 2)
>>> a(2, 3)(4, 5)
(1 3 2)(4 5)
"""
rv = Cycle(*other)
for k, v in zip(list(self.keys()), [rv[self[k]] for k in self.keys()]):
rv[k] = v
return rv
def list(self, size=None):
"""Return the cycles as an explicit list starting from 0 up
to the greater of the largest value in the cycles and size.
Truncation of trailing unmoved items will occur when size
is less than the maximum element in the cycle; if this is
desired, setting ``size=-1`` will guarantee such trimming.
Examples
========
>>> from sympy.combinatorics.permutations import Cycle
>>> from sympy.combinatorics.permutations import Permutation
>>> Permutation.print_cyclic = False
>>> p = Cycle(2, 3)(4, 5)
>>> p.list()
[0, 1, 3, 2, 5, 4]
>>> p.list(10)
[0, 1, 3, 2, 5, 4, 6, 7, 8, 9]
Passing a length too small will trim trailing, unchanged elements
in the permutation:
>>> Cycle(2, 4)(1, 2, 4).list(-1)
[0, 2, 1]
"""
if not self and size is None:
raise ValueError('must give size for empty Cycle')
if size is not None:
big = max([i for i in self.keys() if self[i] != i] + [0])
size = max(size, big + 1)
else:
size = self.size
return [self[i] for i in range(size)]
def __repr__(self):
"""We want it to print as a Cycle, not as a dict.
Examples
========
>>> from sympy.combinatorics import Cycle
>>> Cycle(1, 2)
(1 2)
>>> print(_)
(1 2)
>>> list(Cycle(1, 2).items())
[(1, 2), (2, 1)]
"""
if not self:
return 'Cycle()'
cycles = Permutation(self).cyclic_form
s = ''.join(str(tuple(c)) for c in cycles)
big = self.size - 1
if not any(i == big for c in cycles for i in c):
s += '(%s)' % big
return 'Cycle%s' % s
def __str__(self):
"""We want it to be printed in a Cycle notation with no
comma in-between.
Examples
========
>>> from sympy.combinatorics import Cycle
>>> Cycle(1, 2)
(1 2)
>>> Cycle(1, 2, 4)(5, 6)
(1 2 4)(5 6)
"""
if not self:
return '()'
cycles = Permutation(self).cyclic_form
s = ''.join(str(tuple(c)) for c in cycles)
big = self.size - 1
if not any(i == big for c in cycles for i in c):
s += '(%s)' % big
s = s.replace(',', '')
return s
def __init__(self, *args):
"""Load up a Cycle instance with the values for the cycle.
Examples
========
>>> from sympy.combinatorics.permutations import Cycle
>>> Cycle(1, 2, 6)
(1 2 6)
"""
if not args:
return
if len(args) == 1:
if isinstance(args[0], Permutation):
for c in args[0].cyclic_form:
self.update(self(*c))
return
elif isinstance(args[0], Cycle):
for k, v in args[0].items():
self[k] = v
return
args = [as_int(a) for a in args]
if any(i < 0 for i in args):
raise ValueError('negative integers are not allowed in a cycle.')
if has_dups(args):
raise ValueError('All elements must be unique in a cycle.')
for i in range(-len(args), 0):
self[args[i]] = args[i + 1]
@property
def size(self):
if not self:
return 0
return max(self.keys()) + 1
def copy(self):
return Cycle(self)
class Permutation(Basic):
"""
A permutation, alternatively known as an 'arrangement number' or 'ordering'
is an arrangement of the elements of an ordered list into a one-to-one
mapping with itself. The permutation of a given arrangement is given by
indicating the positions of the elements after re-arrangement [2]_. For
example, if one started with elements [x, y, a, b] (in that order) and
they were reordered as [x, y, b, a] then the permutation would be
[0, 1, 3, 2]. Notice that (in SymPy) the first element is always referred
to as 0 and the permutation uses the indices of the elements in the
original ordering, not the elements (a, b, etc...) themselves.
>>> from sympy.combinatorics import Permutation
>>> Permutation.print_cyclic = False
Permutations Notation
=====================
Permutations are commonly represented in disjoint cycle or array forms.
Array Notation and 2-line Form
------------------------------------
In the 2-line form, the elements and their final positions are shown
as a matrix with 2 rows:
[0 1 2 ... n-1]
[p(0) p(1) p(2) ... p(n-1)]
Since the first line is always range(n), where n is the size of p,
it is sufficient to represent the permutation by the second line,
referred to as the "array form" of the permutation. This is entered
in brackets as the argument to the Permutation class:
>>> p = Permutation([0, 2, 1]); p
Permutation([0, 2, 1])
Given i in range(p.size), the permutation maps i to i^p
>>> [i^p for i in range(p.size)]
[0, 2, 1]
The composite of two permutations p*q means first apply p, then q, so
i^(p*q) = (i^p)^q which is i^p^q according to Python precedence rules:
>>> q = Permutation([2, 1, 0])
>>> [i^p^q for i in range(3)]
[2, 0, 1]
>>> [i^(p*q) for i in range(3)]
[2, 0, 1]
One can use also the notation p(i) = i^p, but then the composition
rule is (p*q)(i) = q(p(i)), not p(q(i)):
>>> [(p*q)(i) for i in range(p.size)]
[2, 0, 1]
>>> [q(p(i)) for i in range(p.size)]
[2, 0, 1]
>>> [p(q(i)) for i in range(p.size)]
[1, 2, 0]
Disjoint Cycle Notation
-----------------------
In disjoint cycle notation, only the elements that have shifted are
indicated. In the above case, the 2 and 1 switched places. This can
be entered in two ways:
>>> Permutation(1, 2) == Permutation([[1, 2]]) == p
True
Only the relative ordering of elements in a cycle matter:
>>> Permutation(1,2,3) == Permutation(2,3,1) == Permutation(3,1,2)
True
The disjoint cycle notation is convenient when representing
permutations that have several cycles in them:
>>> Permutation(1, 2)(3, 5) == Permutation([[1, 2], [3, 5]])
True
It also provides some economy in entry when computing products of
permutations that are written in disjoint cycle notation:
>>> Permutation(1, 2)(1, 3)(2, 3)
Permutation([0, 3, 2, 1])
>>> _ == Permutation([[1, 2]])*Permutation([[1, 3]])*Permutation([[2, 3]])
True
Caution: when the cycles have common elements
between them then the order in which the
permutations are applied matters. The
convention is that the permutations are
applied from *right to left*. In the following, the
transposition of elements 2 and 3 is followed
by the transposition of elements 1 and 2:
>>> Permutation(1, 2)(2, 3) == Permutation([(1, 2), (2, 3)])
True
>>> Permutation(1, 2)(2, 3).list()
[0, 3, 1, 2]
If the first and second elements had been
swapped first, followed by the swapping of the second
and third, the result would have been [0, 2, 3, 1].
If, for some reason, you want to apply the cycles
in the order they are entered, you can simply reverse
the order of cycles:
>>> Permutation([(1, 2), (2, 3)][::-1]).list()
[0, 2, 3, 1]
Entering a singleton in a permutation is a way to indicate the size of the
permutation. The ``size`` keyword can also be used.
Array-form entry:
>>> Permutation([[1, 2], [9]])
Permutation([0, 2, 1], size=10)
>>> Permutation([[1, 2]], size=10)
Permutation([0, 2, 1], size=10)
Cyclic-form entry:
>>> Permutation(1, 2, size=10)
Permutation([0, 2, 1], size=10)
>>> Permutation(9)(1, 2)
Permutation([0, 2, 1], size=10)
Caution: no singleton containing an element larger than the largest
in any previous cycle can be entered. This is an important difference
in how Permutation and Cycle handle the __call__ syntax. A singleton
argument at the start of a Permutation performs instantiation of the
Permutation and is permitted:
>>> Permutation(5)
Permutation([], size=6)
A singleton entered after instantiation is a call to the permutation
-- a function call -- and if the argument is out of range it will
trigger an error. For this reason, it is better to start the cycle
with the singleton:
The following fails because there is is no element 3:
>>> Permutation(1, 2)(3)
Traceback (most recent call last):
...
IndexError: list index out of range
This is ok: only the call to an out of range singleton is prohibited;
otherwise the permutation autosizes:
>>> Permutation(3)(1, 2)
Permutation([0, 2, 1, 3])
>>> Permutation(1, 2)(3, 4) == Permutation(3, 4)(1, 2)
True
Equality testing
----------------
The array forms must be the same in order for permutations to be equal:
>>> Permutation([1, 0, 2, 3]) == Permutation([1, 0])
False
Identity Permutation
--------------------
The identity permutation is a permutation in which no element is out of
place. It can be entered in a variety of ways. All the following create
an identity permutation of size 4:
>>> I = Permutation([0, 1, 2, 3])
>>> all(p == I for p in [
... Permutation(3),
... Permutation(range(4)),
... Permutation([], size=4),
... Permutation(size=4)])
True
Watch out for entering the range *inside* a set of brackets (which is
cycle notation):
>>> I == Permutation([range(4)])
False
Permutation Printing
====================
There are a few things to note about how Permutations are printed.
1) If you prefer one form (array or cycle) over another, you can set that
with the print_cyclic flag.
>>> Permutation(1, 2)(4, 5)(3, 4)
Permutation([0, 2, 1, 4, 5, 3])
>>> p = _
>>> Permutation.print_cyclic = True
>>> p
(1 2)(3 4 5)
>>> Permutation.print_cyclic = False
2) Regardless of the setting, a list of elements in the array for cyclic
form can be obtained and either of those can be copied and supplied as
the argument to Permutation:
>>> p.array_form
[0, 2, 1, 4, 5, 3]
>>> p.cyclic_form
[[1, 2], [3, 4, 5]]
>>> Permutation(_) == p
True
3) Printing is economical in that as little as possible is printed while
retaining all information about the size of the permutation:
>>> Permutation([1, 0, 2, 3])
Permutation([1, 0, 2, 3])
>>> Permutation([1, 0, 2, 3], size=20)
Permutation([1, 0], size=20)
>>> Permutation([1, 0, 2, 4, 3, 5, 6], size=20)
Permutation([1, 0, 2, 4, 3], size=20)
>>> p = Permutation([1, 0, 2, 3])
>>> Permutation.print_cyclic = True
>>> p
(3)(0 1)
>>> Permutation.print_cyclic = False
The 2 was not printed but it is still there as can be seen with the
array_form and size methods:
>>> p.array_form
[1, 0, 2, 3]
>>> p.size
4
Short introduction to other methods
===================================
The permutation can act as a bijective function, telling what element is
located at a given position
>>> q = Permutation([5, 2, 3, 4, 1, 0])
>>> q.array_form[1] # the hard way
2
>>> q(1) # the easy way
2
>>> {i: q(i) for i in range(q.size)} # showing the bijection
{0: 5, 1: 2, 2: 3, 3: 4, 4: 1, 5: 0}
The full cyclic form (including singletons) can be obtained:
>>> p.full_cyclic_form
[[0, 1], [2], [3]]
Any permutation can be factored into transpositions of pairs of elements:
>>> Permutation([[1, 2], [3, 4, 5]]).transpositions()
[(1, 2), (3, 5), (3, 4)]
>>> Permutation.rmul(*[Permutation([ti], size=6) for ti in _]).cyclic_form
[[1, 2], [3, 4, 5]]
The number of permutations on a set of n elements is given by n! and is
called the cardinality.
>>> p.size
4
>>> p.cardinality
24
A given permutation has a rank among all the possible permutations of the
same elements, but what that rank is depends on how the permutations are
enumerated. (There are a number of different methods of doing so.) The
lexicographic rank is given by the rank method and this rank is used to
increment a permutation with addition/subtraction:
>>> p.rank()
6
>>> p + 1
Permutation([1, 0, 3, 2])
>>> p.next_lex()
Permutation([1, 0, 3, 2])
>>> _.rank()
7
>>> p.unrank_lex(p.size, rank=7)
Permutation([1, 0, 3, 2])
The product of two permutations p and q is defined as their composition as
functions, (p*q)(i) = q(p(i)) [6]_.
>>> p = Permutation([1, 0, 2, 3])
>>> q = Permutation([2, 3, 1, 0])
>>> list(q*p)
[2, 3, 0, 1]
>>> list(p*q)
[3, 2, 1, 0]
>>> [q(p(i)) for i in range(p.size)]
[3, 2, 1, 0]
The permutation can be 'applied' to any list-like object, not only
Permutations:
>>> p(['zero', 'one', 'four', 'two'])
['one', 'zero', 'four', 'two']
>>> p('zo42')
['o', 'z', '4', '2']
If you have a list of arbitrary elements, the corresponding permutation
can be found with the from_sequence method:
>>> Permutation.from_sequence('SymPy')
Permutation([1, 3, 2, 0, 4])
See Also
========
Cycle
References
==========
.. [1] Skiena, S. 'Permutations.' 1.1 in Implementing Discrete Mathematics
Combinatorics and Graph Theory with Mathematica. Reading, MA:
Addison-Wesley, pp. 3-16, 1990.
.. [2] Knuth, D. E. The Art of Computer Programming, Vol. 4: Combinatorial
Algorithms, 1st ed. Reading, MA: Addison-Wesley, 2011.
.. [3] Wendy Myrvold and Frank Ruskey. 2001. Ranking and unranking
permutations in linear time. Inf. Process. Lett. 79, 6 (September 2001),
281-284. DOI=10.1016/S0020-0190(01)00141-7
.. [4] D. L. Kreher, D. R. Stinson 'Combinatorial Algorithms'
CRC Press, 1999
.. [5] Graham, R. L.; Knuth, D. E.; and Patashnik, O.
Concrete Mathematics: A Foundation for Computer Science, 2nd ed.
Reading, MA: Addison-Wesley, 1994.
.. [6] https://en.wikipedia.org/wiki/Permutation#Product_and_inverse
.. [7] https://en.wikipedia.org/wiki/Lehmer_code
"""
is_Permutation = True
_array_form = None
_cyclic_form = None
_cycle_structure = None
_size = None
_rank = None
def __new__(cls, *args, **kwargs):
"""
Constructor for the Permutation object from a list or a
list of lists in which all elements of the permutation may
appear only once.
Examples
========
>>> from sympy.combinatorics.permutations import Permutation
>>> Permutation.print_cyclic = False
Permutations entered in array-form are left unaltered:
>>> Permutation([0, 2, 1])
Permutation([0, 2, 1])
Permutations entered in cyclic form are converted to array form;
singletons need not be entered, but can be entered to indicate the
largest element:
>>> Permutation([[4, 5, 6], [0, 1]])
Permutation([1, 0, 2, 3, 5, 6, 4])
>>> Permutation([[4, 5, 6], [0, 1], [19]])
Permutation([1, 0, 2, 3, 5, 6, 4], size=20)
All manipulation of permutations assumes that the smallest element
is 0 (in keeping with 0-based indexing in Python) so if the 0 is
missing when entering a permutation in array form, an error will be
raised:
>>> Permutation([2, 1])
Traceback (most recent call last):
...
ValueError: Integers 0 through 2 must be present.
If a permutation is entered in cyclic form, it can be entered without
singletons and the ``size`` specified so those values can be filled
in, otherwise the array form will only extend to the maximum value
in the cycles:
>>> Permutation([[1, 4], [3, 5, 2]], size=10)
Permutation([0, 4, 3, 5, 1, 2], size=10)
>>> _.array_form
[0, 4, 3, 5, 1, 2, 6, 7, 8, 9]
"""
size = kwargs.pop('size', None)
if size is not None:
size = int(size)
#a) ()
#b) (1) = identity
#c) (1, 2) = cycle
#d) ([1, 2, 3]) = array form
#e) ([[1, 2]]) = cyclic form
#f) (Cycle) = conversion to permutation
#g) (Permutation) = adjust size or return copy
ok = True
if not args: # a
return cls._af_new(list(range(size or 0)))
elif len(args) > 1: # c
return cls._af_new(Cycle(*args).list(size))
if len(args) == 1:
a = args[0]
if isinstance(a, cls): # g
if size is None or size == a.size:
return a
return cls(a.array_form, size=size)
if isinstance(a, Cycle): # f
return cls._af_new(a.list(size))
if not is_sequence(a): # b
return cls._af_new(list(range(a + 1)))
if has_variety(is_sequence(ai) for ai in a):
ok = False
else:
ok = False
if not ok:
raise ValueError("Permutation argument must be a list of ints, "
"a list of lists, Permutation or Cycle.")
# safe to assume args are valid; this also makes a copy
# of the args
args = list(args[0])
is_cycle = args and is_sequence(args[0])
if is_cycle: # e
args = [[int(i) for i in c] for c in args]
else: # d
args = [int(i) for i in args]
# if there are n elements present, 0, 1, ..., n-1 should be present
# unless a cycle notation has been provided. A 0 will be added
# for convenience in case one wants to enter permutations where
# counting starts from 1.
temp = flatten(args)
if has_dups(temp) and not is_cycle:
raise ValueError('there were repeated elements.')
temp = set(temp)
if not is_cycle and \
any(i not in temp for i in range(len(temp))):
raise ValueError("Integers 0 through %s must be present." %
max(temp))
if is_cycle:
# it's not necessarily canonical so we won't store
# it -- use the array form instead
c = Cycle()
for ci in args:
c = c(*ci)
aform = c.list()
else:
aform = list(args)
if size and size > len(aform):
# don't allow for truncation of permutation which
# might split a cycle and lead to an invalid aform
# but do allow the permutation size to be increased
aform.extend(list(range(len(aform), size)))
return cls._af_new(aform)
@classmethod
def _af_new(cls, perm):
"""A method to produce a Permutation object from a list;
the list is bound to the _array_form attribute, so it must
not be modified; this method is meant for internal use only;
the list ``a`` is supposed to be generated as a temporary value
in a method, so p = Perm._af_new(a) is the only object
to hold a reference to ``a``::
Examples
========
>>> from sympy.combinatorics.permutations import Perm
>>> Perm.print_cyclic = False
>>> a = [2,1,3,0]
>>> p = Perm._af_new(a)
>>> p
Permutation([2, 1, 3, 0])
"""
p = Basic.__new__(cls, perm)
p._array_form = perm
p._size = len(perm)
return p
def _hashable_content(self):
# the array_form (a list) is the Permutation arg, so we need to
# return a tuple, instead
return tuple(self.array_form)
@property
def array_form(self):
"""
Return a copy of the attribute _array_form
Examples
========
>>> from sympy.combinatorics.permutations import Permutation
>>> Permutation.print_cyclic = False
>>> p = Permutation([[2, 0], [3, 1]])
>>> p.array_form
[2, 3, 0, 1]
>>> Permutation([[2, 0, 3, 1]]).array_form
[3, 2, 0, 1]
>>> Permutation([2, 0, 3, 1]).array_form
[2, 0, 3, 1]
>>> Permutation([[1, 2], [4, 5]]).array_form
[0, 2, 1, 3, 5, 4]
"""
return self._array_form[:]
def __repr__(self):
from sympy.combinatorics.permutations import Permutation, Cycle
if Permutation.print_cyclic:
if not self.size:
return 'Permutation()'
# before taking Cycle notation, see if the last element is
# a singleton and move it to the head of the string
s = Cycle(self)(self.size - 1).__repr__()[len('Cycle'):]
last = s.rfind('(')
if not last == 0 and ',' not in s[last:]:
s = s[last:] + s[:last]
return 'Permutation%s' %s
else:
s = self.support()
if not s:
if self.size < 5:
return 'Permutation(%s)' % str(self.array_form)
return 'Permutation([], size=%s)' % self.size
trim = str(self.array_form[:s[-1] + 1]) + ', size=%s' % self.size
use = full = str(self.array_form)
if len(trim) < len(full):
use = trim
return 'Permutation(%s)' % use
def list(self, size=None):
"""Return the permutation as an explicit list, possibly
trimming unmoved elements if size is less than the maximum
element in the permutation; if this is desired, setting
``size=-1`` will guarantee such trimming.
Examples
========
>>> from sympy.combinatorics.permutations import Permutation
>>> Permutation.print_cyclic = False
>>> p = Permutation(2, 3)(4, 5)
>>> p.list()
[0, 1, 3, 2, 5, 4]
>>> p.list(10)
[0, 1, 3, 2, 5, 4, 6, 7, 8, 9]
Passing a length too small will trim trailing, unchanged elements
in the permutation:
>>> Permutation(2, 4)(1, 2, 4).list(-1)
[0, 2, 1]
>>> Permutation(3).list(-1)
[]
"""
if not self and size is None:
raise ValueError('must give size for empty Cycle')
rv = self.array_form
if size is not None:
if size > self.size:
rv.extend(list(range(self.size, size)))
else:
# find first value from rhs where rv[i] != i
i = self.size - 1
while rv:
if rv[-1] != i:
break
rv.pop()
i -= 1
return rv
@property
def cyclic_form(self):
"""
This is used to convert to the cyclic notation
from the canonical notation. Singletons are omitted.
Examples
========
>>> from sympy.combinatorics.permutations import Permutation
>>> Permutation.print_cyclic = False
>>> p = Permutation([0, 3, 1, 2])
>>> p.cyclic_form
[[1, 3, 2]]
>>> Permutation([1, 0, 2, 4, 3, 5]).cyclic_form
[[0, 1], [3, 4]]
See Also
========
array_form, full_cyclic_form
"""
if self._cyclic_form is not None:
return list(self._cyclic_form)
array_form = self.array_form
unchecked = [True] * len(array_form)
cyclic_form = []
for i in range(len(array_form)):
if unchecked[i]:
cycle = []
cycle.append(i)
unchecked[i] = False
j = i
while unchecked[array_form[j]]:
j = array_form[j]
cycle.append(j)
unchecked[j] = False
if len(cycle) > 1:
cyclic_form.append(cycle)
assert cycle == list(minlex(cycle, is_set=True))
cyclic_form.sort()
self._cyclic_form = cyclic_form[:]
return cyclic_form
@property
def full_cyclic_form(self):
"""Return permutation in cyclic form including singletons.
Examples
========
>>> from sympy.combinatorics.permutations import Permutation
>>> Permutation([0, 2, 1]).full_cyclic_form
[[0], [1, 2]]
"""
need = set(range(self.size)) - set(flatten(self.cyclic_form))
rv = self.cyclic_form
rv.extend([[i] for i in need])
rv.sort()
return rv
@property
def size(self):
"""
Returns the number of elements in the permutation.
Examples
========
>>> from sympy.combinatorics import Permutation
>>> Permutation([[3, 2], [0, 1]]).size
4
See Also
========
cardinality, length, order, rank
"""
return self._size
def support(self):
"""Return the elements in permutation, P, for which P[i] != i.
Examples
========
>>> from sympy.combinatorics import Permutation
>>> p = Permutation([[3, 2], [0, 1], [4]])
>>> p.array_form
[1, 0, 3, 2, 4]
>>> p.support()
[0, 1, 2, 3]
"""
a = self.array_form
return [i for i, e in enumerate(a) if a[i] != i]
def __add__(self, other):
"""Return permutation that is other higher in rank than self.
The rank is the lexicographical rank, with the identity permutation
having rank of 0.
Examples
========
>>> from sympy.combinatorics.permutations import Permutation
>>> Permutation.print_cyclic = False
>>> I = Permutation([0, 1, 2, 3])
>>> a = Permutation([2, 1, 3, 0])
>>> I + a.rank() == a
True
See Also
========
__sub__, inversion_vector
"""
rank = (self.rank() + other) % self.cardinality
rv = self.unrank_lex(self.size, rank)
rv._rank = rank
return rv
def __sub__(self, other):
"""Return the permutation that is other lower in rank than self.
See Also
========
__add__
"""
return self.__add__(-other)
@staticmethod
def rmul(*args):
"""
Return product of Permutations [a, b, c, ...] as the Permutation whose
ith value is a(b(c(i))).
a, b, c, ... can be Permutation objects or tuples.
Examples
========
>>> from sympy.combinatorics.permutations import _af_rmul, Permutation
>>> Permutation.print_cyclic = False
>>> a, b = [1, 0, 2], [0, 2, 1]
>>> a = Permutation(a); b = Permutation(b)
>>> list(Permutation.rmul(a, b))
[1, 2, 0]
>>> [a(b(i)) for i in range(3)]
[1, 2, 0]
This handles the operands in reverse order compared to the ``*`` operator:
>>> a = Permutation(a); b = Permutation(b)
>>> list(a*b)
[2, 0, 1]
>>> [b(a(i)) for i in range(3)]
[2, 0, 1]
Notes
=====
All items in the sequence will be parsed by Permutation as
necessary as long as the first item is a Permutation:
>>> Permutation.rmul(a, [0, 2, 1]) == Permutation.rmul(a, b)
True
The reverse order of arguments will raise a TypeError.
"""
rv = args[0]
for i in range(1, len(args)):
rv = args[i]*rv
return rv
@classmethod
def rmul_with_af(cls, *args):
"""
same as rmul, but the elements of args are Permutation objects
which have _array_form
"""
a = [x._array_form for x in args]
rv = cls._af_new(_af_rmuln(*a))
return rv
def mul_inv(self, other):
"""
other*~self, self and other have _array_form
"""
a = _af_invert(self._array_form)
b = other._array_form
return self._af_new(_af_rmul(a, b))
def __rmul__(self, other):
"""This is needed to coerce other to Permutation in rmul."""
cls = type(self)
return cls(other)*self
def __mul__(self, other):
"""
Return the product a*b as a Permutation; the ith value is b(a(i)).
Examples
========
>>> from sympy.combinatorics.permutations import _af_rmul, Permutation
>>> Permutation.print_cyclic = False
>>> a, b = [1, 0, 2], [0, 2, 1]
>>> a = Permutation(a); b = Permutation(b)
>>> list(a*b)
[2, 0, 1]
>>> [b(a(i)) for i in range(3)]
[2, 0, 1]
This handles operands in reverse order compared to _af_rmul and rmul:
>>> al = list(a); bl = list(b)
>>> _af_rmul(al, bl)
[1, 2, 0]
>>> [al[bl[i]] for i in range(3)]
[1, 2, 0]
It is acceptable for the arrays to have different lengths; the shorter
one will be padded to match the longer one:
>>> b*Permutation([1, 0])
Permutation([1, 2, 0])
>>> Permutation([1, 0])*b
Permutation([2, 0, 1])
It is also acceptable to allow coercion to handle conversion of a
single list to the left of a Permutation:
>>> [0, 1]*a # no change: 2-element identity
Permutation([1, 0, 2])
>>> [[0, 1]]*a # exchange first two elements
Permutation([0, 1, 2])
You cannot use more than 1 cycle notation in a product of cycles
since coercion can only handle one argument to the left. To handle
multiple cycles it is convenient to use Cycle instead of Permutation:
>>> [[1, 2]]*[[2, 3]]*Permutation([]) # doctest: +SKIP
>>> from sympy.combinatorics.permutations import Cycle
>>> Cycle(1, 2)(2, 3)
(1 3 2)
"""
a = self.array_form
# __rmul__ makes sure the other is a Permutation
b = other.array_form
if not b:
perm = a
else:
b.extend(list(range(len(b), len(a))))
perm = [b[i] for i in a] + b[len(a):]
return self._af_new(perm)
def commutes_with(self, other):
"""
Checks if the elements are commuting.
Examples
========
>>> from sympy.combinatorics.permutations import Permutation
>>> a = Permutation([1, 4, 3, 0, 2, 5])
>>> b = Permutation([0, 1, 2, 3, 4, 5])
>>> a.commutes_with(b)
True
>>> b = Permutation([2, 3, 5, 4, 1, 0])
>>> a.commutes_with(b)
False
"""
a = self.array_form
b = other.array_form
return _af_commutes_with(a, b)
def __pow__(self, n):
"""
Routine for finding powers of a permutation.
Examples
========
>>> from sympy.combinatorics.permutations import Permutation
>>> Permutation.print_cyclic = False
>>> p = Permutation([2,0,3,1])
>>> p.order()
4
>>> p**4
Permutation([0, 1, 2, 3])
"""
if isinstance(n, Permutation):
raise NotImplementedError(
'p**p is not defined; do you mean p^p (conjugate)?')
n = int(n)
return self._af_new(_af_pow(self.array_form, n))
def __rxor__(self, i):
"""Return self(i) when ``i`` is an int.
Examples
========
>>> from sympy.combinatorics import Permutation
>>> p = Permutation(1, 2, 9)
>>> 2^p == p(2) == 9
True
"""
if int(i) == i:
return self(i)
else:
raise NotImplementedError(
"i^p = p(i) when i is an integer, not %s." % i)
def __xor__(self, h):
"""Return the conjugate permutation ``~h*self*h` `.
If ``a`` and ``b`` are conjugates, ``a = h*b*~h`` and
``b = ~h*a*h`` and both have the same cycle structure.
Examples
========
>>> from sympy.combinatorics.permutations import Permutation
>>> Permutation.print_cyclic = True
>>> p = Permutation(1, 2, 9)
>>> q = Permutation(6, 9, 8)
>>> p*q != q*p
True
Calculate and check properties of the conjugate:
>>> c = p^q
>>> c == ~q*p*q and p == q*c*~q
True
The expression q^p^r is equivalent to q^(p*r):
>>> r = Permutation(9)(4, 6, 8)
>>> q^p^r == q^(p*r)
True
If the term to the left of the conjugate operator, i, is an integer
then this is interpreted as selecting the ith element from the
permutation to the right:
>>> all(i^p == p(i) for i in range(p.size))
True
Note that the * operator as higher precedence than the ^ operator:
>>> q^r*p^r == q^(r*p)^r == Permutation(9)(1, 6, 4)
True
Notes
=====
In Python the precedence rule is p^q^r = (p^q)^r which differs
in general from p^(q^r)
>>> q^p^r
(9)(1 4 8)
>>> q^(p^r)
(9)(1 8 6)
For a given r and p, both of the following are conjugates of p:
~r*p*r and r*p*~r. But these are not necessarily the same:
>>> ~r*p*r == r*p*~r
True
>>> p = Permutation(1, 2, 9)(5, 6)
>>> ~r*p*r == r*p*~r
False
The conjugate ~r*p*r was chosen so that ``p^q^r`` would be equivalent
to ``p^(q*r)`` rather than ``p^(r*q)``. To obtain r*p*~r, pass ~r to
this method:
>>> p^~r == r*p*~r
True
"""
if self.size != h.size:
raise ValueError("The permutations must be of equal size.")
a = [None]*self.size
h = h._array_form
p = self._array_form
for i in range(self.size):
a[h[i]] = h[p[i]]
return self._af_new(a)
def transpositions(self):
"""
Return the permutation decomposed into a list of transpositions.
It is always possible to express a permutation as the product of
transpositions, see [1]
Examples
========
>>> from sympy.combinatorics.permutations import Permutation
>>> p = Permutation([[1, 2, 3], [0, 4, 5, 6, 7]])
>>> t = p.transpositions()
>>> t
[(0, 7), (0, 6), (0, 5), (0, 4), (1, 3), (1, 2)]
>>> print(''.join(str(c) for c in t))
(0, 7)(0, 6)(0, 5)(0, 4)(1, 3)(1, 2)
>>> Permutation.rmul(*[Permutation([ti], size=p.size) for ti in t]) == p
True
References
==========
.. [1] https://en.wikipedia.org/wiki/Transposition_%28mathematics%29#Properties
"""
a = self.cyclic_form
res = []
for x in a:
nx = len(x)
if nx == 2:
res.append(tuple(x))
elif nx > 2:
first = x[0]
for y in x[nx - 1:0:-1]:
res.append((first, y))
return res
@classmethod
def from_sequence(self, i, key=None):
"""Return the permutation needed to obtain ``i`` from the sorted
elements of ``i``. If custom sorting is desired, a key can be given.
Examples
========
>>> from sympy.combinatorics import Permutation
>>> Permutation.print_cyclic = True
>>> Permutation.from_sequence('SymPy')
(4)(0 1 3)
>>> _(sorted("SymPy"))
['S', 'y', 'm', 'P', 'y']
>>> Permutation.from_sequence('SymPy', key=lambda x: x.lower())
(4)(0 2)(1 3)
"""
ic = list(zip(i, list(range(len(i)))))
if key:
ic.sort(key=lambda x: key(x[0]))
else:
ic.sort()
return ~Permutation([i[1] for i in ic])
def __invert__(self):
"""
Return the inverse of the permutation.
A permutation multiplied by its inverse is the identity permutation.
Examples
========
>>> from sympy.combinatorics.permutations import Permutation
>>> Permutation.print_cyclic = False
>>> p = Permutation([[2,0], [3,1]])
>>> ~p
Permutation([2, 3, 0, 1])
>>> _ == p**-1
True
>>> p*~p == ~p*p == Permutation([0, 1, 2, 3])
True
"""
return self._af_new(_af_invert(self._array_form))
def __iter__(self):
"""Yield elements from array form.
Examples
========
>>> from sympy.combinatorics import Permutation
>>> list(Permutation(range(3)))
[0, 1, 2]
"""
for i in self.array_form:
yield i
def __call__(self, *i):
"""
Allows applying a permutation instance as a bijective function.
Examples
========
>>> from sympy.combinatorics.permutations import Permutation
>>> p = Permutation([[2, 0], [3, 1]])
>>> p.array_form
[2, 3, 0, 1]
>>> [p(i) for i in range(4)]
[2, 3, 0, 1]
If an array is given then the permutation selects the items
from the array (i.e. the permutation is applied to the array):
>>> from sympy.abc import x
>>> p([x, 1, 0, x**2])
[0, x**2, x, 1]
"""
# list indices can be Integer or int; leave this
# as it is (don't test or convert it) because this
# gets called a lot and should be fast
if len(i) == 1:
i = i[0]
try:
# P(1)
return self._array_form[i]
except TypeError:
try:
# P([a, b, c])
return [i[j] for j in self._array_form]
except Exception:
raise TypeError('unrecognized argument')
else:
# P(1, 2, 3)
return self*Permutation(Cycle(*i), size=self.size)
def atoms(self):
"""
Returns all the elements of a permutation
Examples
========
>>> from sympy.combinatorics import Permutation
>>> Permutation([0, 1, 2, 3, 4, 5]).atoms()
{0, 1, 2, 3, 4, 5}
>>> Permutation([[0, 1], [2, 3], [4, 5]]).atoms()
{0, 1, 2, 3, 4, 5}
"""
return set(self.array_form)
def next_lex(self):
"""
Returns the next permutation in lexicographical order.
If self is the last permutation in lexicographical order
it returns None.
See [4] section 2.4.
Examples
========
>>> from sympy.combinatorics.permutations import Permutation
>>> p = Permutation([2, 3, 1, 0])
>>> p = Permutation([2, 3, 1, 0]); p.rank()
17
>>> p = p.next_lex(); p.rank()
18
See Also
========
rank, unrank_lex
"""
perm = self.array_form[:]
n = len(perm)
i = n - 2
while perm[i + 1] < perm[i]:
i -= 1
if i == -1:
return None
else:
j = n - 1
while perm[j] < perm[i]:
j -= 1
perm[j], perm[i] = perm[i], perm[j]
i += 1
j = n - 1
while i < j:
perm[j], perm[i] = perm[i], perm[j]
i += 1
j -= 1
return self._af_new(perm)
@classmethod
def unrank_nonlex(self, n, r):
"""
This is a linear time unranking algorithm that does not
respect lexicographic order [3].
Examples
========
>>> from sympy.combinatorics.permutations import Permutation
>>> Permutation.print_cyclic = False
>>> Permutation.unrank_nonlex(4, 5)
Permutation([2, 0, 3, 1])
>>> Permutation.unrank_nonlex(4, -1)
Permutation([0, 1, 2, 3])
See Also
========
next_nonlex, rank_nonlex
"""
def _unrank1(n, r, a):
if n > 0:
a[n - 1], a[r % n] = a[r % n], a[n - 1]
_unrank1(n - 1, r//n, a)
id_perm = list(range(n))
n = int(n)
r = r % ifac(n)
_unrank1(n, r, id_perm)
return self._af_new(id_perm)
def rank_nonlex(self, inv_perm=None):
"""
This is a linear time ranking algorithm that does not
enforce lexicographic order [3].
Examples
========
>>> from sympy.combinatorics.permutations import Permutation
>>> p = Permutation([0, 1, 2, 3])
>>> p.rank_nonlex()
23
See Also
========
next_nonlex, unrank_nonlex
"""
def _rank1(n, perm, inv_perm):
if n == 1:
return 0
s = perm[n - 1]
t = inv_perm[n - 1]
perm[n - 1], perm[t] = perm[t], s
inv_perm[n - 1], inv_perm[s] = inv_perm[s], t
return s + n*_rank1(n - 1, perm, inv_perm)
if inv_perm is None:
inv_perm = (~self).array_form
if not inv_perm:
return 0
perm = self.array_form[:]
r = _rank1(len(perm), perm, inv_perm)
return r
def next_nonlex(self):
"""
Returns the next permutation in nonlex order [3].
If self is the last permutation in this order it returns None.
Examples
========
>>> from sympy.combinatorics.permutations import Permutation
>>> Permutation.print_cyclic = False
>>> p = Permutation([2, 0, 3, 1]); p.rank_nonlex()
5
>>> p = p.next_nonlex(); p
Permutation([3, 0, 1, 2])
>>> p.rank_nonlex()
6
See Also
========
rank_nonlex, unrank_nonlex
"""
r = self.rank_nonlex()
if r == ifac(self.size) - 1:
return None
return self.unrank_nonlex(self.size, r + 1)
def rank(self):
"""
Returns the lexicographic rank of the permutation.
Examples
========
>>> from sympy.combinatorics.permutations import Permutation
>>> p = Permutation([0, 1, 2, 3])
>>> p.rank()
0
>>> p = Permutation([3, 2, 1, 0])
>>> p.rank()
23
See Also
========
next_lex, unrank_lex, cardinality, length, order, size
"""
if not self._rank is None:
return self._rank
rank = 0
rho = self.array_form[:]
n = self.size - 1
size = n + 1
psize = int(ifac(n))
for j in range(size - 1):
rank += rho[j]*psize
for i in range(j + 1, size):
if rho[i] > rho[j]:
rho[i] -= 1
psize //= n
n -= 1
self._rank = rank
return rank
@property
def cardinality(self):
"""
Returns the number of all possible permutations.
Examples
========
>>> from sympy.combinatorics.permutations import Permutation
>>> p = Permutation([0, 1, 2, 3])
>>> p.cardinality
24
See Also
========
length, order, rank, size
"""
return int(ifac(self.size))
def parity(self):
"""
Computes the parity of a permutation.
The parity of a permutation reflects the parity of the
number of inversions in the permutation, i.e., the
number of pairs of x and y such that ``x > y`` but ``p[x] < p[y]``.
Examples
========
>>> from sympy.combinatorics.permutations import Permutation
>>> p = Permutation([0, 1, 2, 3])
>>> p.parity()
0
>>> p = Permutation([3, 2, 0, 1])
>>> p.parity()
1
See Also
========
_af_parity
"""
if self._cyclic_form is not None:
return (self.size - self.cycles) % 2
return _af_parity(self.array_form)
@property
def is_even(self):
"""
Checks if a permutation is even.
Examples
========
>>> from sympy.combinatorics.permutations import Permutation
>>> p = Permutation([0, 1, 2, 3])
>>> p.is_even
True
>>> p = Permutation([3, 2, 1, 0])
>>> p.is_even
True
See Also
========
is_odd
"""
return not self.is_odd
@property
def is_odd(self):
"""
Checks if a permutation is odd.
Examples
========
>>> from sympy.combinatorics.permutations import Permutation
>>> p = Permutation([0, 1, 2, 3])
>>> p.is_odd
False
>>> p = Permutation([3, 2, 0, 1])
>>> p.is_odd
True
See Also
========
is_even
"""
return bool(self.parity() % 2)
@property
def is_Singleton(self):
"""
Checks to see if the permutation contains only one number and is
thus the only possible permutation of this set of numbers
Examples
========
>>> from sympy.combinatorics import Permutation
>>> Permutation([0]).is_Singleton
True
>>> Permutation([0, 1]).is_Singleton
False
See Also
========
is_Empty
"""
return self.size == 1
@property
def is_Empty(self):
"""
Checks to see if the permutation is a set with zero elements
Examples
========
>>> from sympy.combinatorics import Permutation
>>> Permutation([]).is_Empty
True
>>> Permutation([0]).is_Empty
False
See Also
========
is_Singleton
"""
return self.size == 0
@property
def is_identity(self):
return self.is_Identity
@property
def is_Identity(self):
"""
Returns True if the Permutation is an identity permutation.
Examples
========
>>> from sympy.combinatorics.permutations import Permutation
>>> p = Permutation([])
>>> p.is_Identity
True
>>> p = Permutation([[0], [1], [2]])
>>> p.is_Identity
True
>>> p = Permutation([0, 1, 2])
>>> p.is_Identity
True
>>> p = Permutation([0, 2, 1])
>>> p.is_Identity
False
See Also
========
order
"""
af = self.array_form
return not af or all(i == af[i] for i in range(self.size))
def ascents(self):
"""
Returns the positions of ascents in a permutation, ie, the location
where p[i] < p[i+1]
Examples
========
>>> from sympy.combinatorics.permutations import Permutation
>>> p = Permutation([4, 0, 1, 3, 2])
>>> p.ascents()
[1, 2]
See Also
========
descents, inversions, min, max
"""
a = self.array_form
pos = [i for i in range(len(a) - 1) if a[i] < a[i + 1]]
return pos
def descents(self):
"""
Returns the positions of descents in a permutation, ie, the location
where p[i] > p[i+1]
Examples
========
>>> from sympy.combinatorics.permutations import Permutation
>>> p = Permutation([4, 0, 1, 3, 2])
>>> p.descents()
[0, 3]
See Also
========
ascents, inversions, min, max
"""
a = self.array_form
pos = [i for i in range(len(a) - 1) if a[i] > a[i + 1]]
return pos
def max(self):
"""
The maximum element moved by the permutation.
Examples
========
>>> from sympy.combinatorics.permutations import Permutation
>>> p = Permutation([1, 0, 2, 3, 4])
>>> p.max()
1
See Also
========
min, descents, ascents, inversions
"""
max = 0
a = self.array_form
for i in range(len(a)):
if a[i] != i and a[i] > max:
max = a[i]
return max
def min(self):
"""
The minimum element moved by the permutation.
Examples
========
>>> from sympy.combinatorics.permutations import Permutation
>>> p = Permutation([0, 1, 4, 3, 2])
>>> p.min()
2
See Also
========
max, descents, ascents, inversions
"""
a = self.array_form
min = len(a)
for i in range(len(a)):
if a[i] != i and a[i] < min:
min = a[i]
return min
def inversions(self):
"""
Computes the number of inversions of a permutation.
An inversion is where i > j but p[i] < p[j].
For small length of p, it iterates over all i and j
values and calculates the number of inversions.
For large length of p, it uses a variation of merge
sort to calculate the number of inversions.
Examples
========
>>> from sympy.combinatorics.permutations import Permutation
>>> p = Permutation([0, 1, 2, 3, 4, 5])
>>> p.inversions()
0
>>> Permutation([3, 2, 1, 0]).inversions()
6
See Also
========
descents, ascents, min, max
References
==========
.. [1] http://www.cp.eng.chula.ac.th/~piak/teaching/algo/algo2008/count-inv.htm
"""
inversions = 0
a = self.array_form
n = len(a)
if n < 130:
for i in range(n - 1):
b = a[i]
for c in a[i + 1:]:
if b > c:
inversions += 1
else:
k = 1
right = 0
arr = a[:]
temp = a[:]
while k < n:
i = 0
while i + k < n:
right = i + k * 2 - 1
if right >= n:
right = n - 1
inversions += _merge(arr, temp, i, i + k, right)
i = i + k * 2
k = k * 2
return inversions
def commutator(self, x):
"""Return the commutator of self and x: ``~x*~self*x*self``
If f and g are part of a group, G, then the commutator of f and g
is the group identity iff f and g commute, i.e. fg == gf.
Examples
========
>>> from sympy.combinatorics.permutations import Permutation
>>> Permutation.print_cyclic = False
>>> p = Permutation([0, 2, 3, 1])
>>> x = Permutation([2, 0, 3, 1])
>>> c = p.commutator(x); c
Permutation([2, 1, 3, 0])
>>> c == ~x*~p*x*p
True
>>> I = Permutation(3)
>>> p = [I + i for i in range(6)]
>>> for i in range(len(p)):
... for j in range(len(p)):
... c = p[i].commutator(p[j])
... if p[i]*p[j] == p[j]*p[i]:
... assert c == I
... else:
... assert c != I
...
References
==========
https://en.wikipedia.org/wiki/Commutator
"""
a = self.array_form
b = x.array_form
n = len(a)
if len(b) != n:
raise ValueError("The permutations must be of equal size.")
inva = [None]*n
for i in range(n):
inva[a[i]] = i
invb = [None]*n
for i in range(n):
invb[b[i]] = i
return self._af_new([a[b[inva[i]]] for i in invb])
def signature(self):
"""
Gives the signature of the permutation needed to place the
elements of the permutation in canonical order.
The signature is calculated as (-1)^<number of inversions>
Examples
========
>>> from sympy.combinatorics.permutations import Permutation
>>> p = Permutation([0, 1, 2])
>>> p.inversions()
0
>>> p.signature()
1
>>> q = Permutation([0,2,1])
>>> q.inversions()
1
>>> q.signature()
-1
See Also
========
inversions
"""
if self.is_even:
return 1
return -1
def order(self):
"""
Computes the order of a permutation.
When the permutation is raised to the power of its
order it equals the identity permutation.
Examples
========
>>> from sympy.combinatorics.permutations import Permutation
>>> Permutation.print_cyclic = False
>>> p = Permutation([3, 1, 5, 2, 4, 0])
>>> p.order()
4
>>> (p**(p.order()))
Permutation([], size=6)
See Also
========
identity, cardinality, length, rank, size
"""
return reduce(lcm, [len(cycle) for cycle in self.cyclic_form], 1)
def length(self):
"""
Returns the number of integers moved by a permutation.
Examples
========
>>> from sympy.combinatorics import Permutation
>>> Permutation([0, 3, 2, 1]).length()
2
>>> Permutation([[0, 1], [2, 3]]).length()
4
See Also
========
min, max, support, cardinality, order, rank, size
"""
return len(self.support())
@property
def cycle_structure(self):
"""Return the cycle structure of the permutation as a dictionary
indicating the multiplicity of each cycle length.
Examples
========
>>> from sympy.combinatorics import Permutation
>>> Permutation.print_cyclic = True
>>> Permutation(3).cycle_structure
{1: 4}
>>> Permutation(0, 4, 3)(1, 2)(5, 6).cycle_structure
{2: 2, 3: 1}
"""
if self._cycle_structure:
rv = self._cycle_structure
else:
rv = defaultdict(int)
singletons = self.size
for c in self.cyclic_form:
rv[len(c)] += 1
singletons -= len(c)
if singletons:
rv[1] = singletons
self._cycle_structure = rv
return dict(rv) # make a copy
@property
def cycles(self):
"""
Returns the number of cycles contained in the permutation
(including singletons).
Examples
========
>>> from sympy.combinatorics import Permutation
>>> Permutation([0, 1, 2]).cycles
3
>>> Permutation([0, 1, 2]).full_cyclic_form
[[0], [1], [2]]
>>> Permutation(0, 1)(2, 3).cycles
2
See Also
========
sympy.functions.combinatorial.numbers.stirling
"""
return len(self.full_cyclic_form)
def index(self):
"""
Returns the index of a permutation.
The index of a permutation is the sum of all subscripts j such
that p[j] is greater than p[j+1].
Examples
========
>>> from sympy.combinatorics.permutations import Permutation
>>> p = Permutation([3, 0, 2, 1, 4])
>>> p.index()
2
"""
a = self.array_form
return sum([j for j in range(len(a) - 1) if a[j] > a[j + 1]])
def runs(self):
"""
Returns the runs of a permutation.
An ascending sequence in a permutation is called a run [5].
Examples
========
>>> from sympy.combinatorics.permutations import Permutation
>>> p = Permutation([2, 5, 7, 3, 6, 0, 1, 4, 8])
>>> p.runs()
[[2, 5, 7], [3, 6], [0, 1, 4, 8]]
>>> q = Permutation([1,3,2,0])
>>> q.runs()
[[1, 3], [2], [0]]
"""
return runs(self.array_form)
def inversion_vector(self):
"""Return the inversion vector of the permutation.
The inversion vector consists of elements whose value
indicates the number of elements in the permutation
that are lesser than it and lie on its right hand side.
The inversion vector is the same as the Lehmer encoding of a
permutation.
Examples
========
>>> from sympy.combinatorics.permutations import Permutation
>>> Permutation.print_cyclic = False
>>> p = Permutation([4, 8, 0, 7, 1, 5, 3, 6, 2])
>>> p.inversion_vector()
[4, 7, 0, 5, 0, 2, 1, 1]
>>> p = Permutation([3, 2, 1, 0])
>>> p.inversion_vector()
[3, 2, 1]
The inversion vector increases lexicographically with the rank
of the permutation, the -ith element cycling through 0..i.
>>> p = Permutation(2)
>>> while p:
... print('%s %s %s' % (p, p.inversion_vector(), p.rank()))
... p = p.next_lex()
...
Permutation([0, 1, 2]) [0, 0] 0
Permutation([0, 2, 1]) [0, 1] 1
Permutation([1, 0, 2]) [1, 0] 2
Permutation([1, 2, 0]) [1, 1] 3
Permutation([2, 0, 1]) [2, 0] 4
Permutation([2, 1, 0]) [2, 1] 5
See Also
========
from_inversion_vector
"""
self_array_form = self.array_form
n = len(self_array_form)
inversion_vector = [0] * (n - 1)
for i in range(n - 1):
val = 0
for j in range(i + 1, n):
if self_array_form[j] < self_array_form[i]:
val += 1
inversion_vector[i] = val
return inversion_vector
def rank_trotterjohnson(self):
"""
Returns the Trotter Johnson rank, which we get from the minimal
change algorithm. See [4] section 2.4.
Examples
========
>>> from sympy.combinatorics.permutations import Permutation
>>> p = Permutation([0, 1, 2, 3])
>>> p.rank_trotterjohnson()
0
>>> p = Permutation([0, 2, 1, 3])
>>> p.rank_trotterjohnson()
7
See Also
========
unrank_trotterjohnson, next_trotterjohnson
"""
if self.array_form == [] or self.is_Identity:
return 0
if self.array_form == [1, 0]:
return 1
perm = self.array_form
n = self.size
rank = 0
for j in range(1, n):
k = 1
i = 0
while perm[i] != j:
if perm[i] < j:
k += 1
i += 1
j1 = j + 1
if rank % 2 == 0:
rank = j1*rank + j1 - k
else:
rank = j1*rank + k - 1
return rank
@classmethod
def unrank_trotterjohnson(cls, size, rank):
"""
Trotter Johnson permutation unranking. See [4] section 2.4.
Examples
========
>>> from sympy.combinatorics.permutations import Permutation
>>> Permutation.unrank_trotterjohnson(5, 10)
Permutation([0, 3, 1, 2, 4])
See Also
========
rank_trotterjohnson, next_trotterjohnson
"""
perm = [0]*size
r2 = 0
n = ifac(size)
pj = 1
for j in range(2, size + 1):
pj *= j
r1 = (rank * pj) // n
k = r1 - j*r2
if r2 % 2 == 0:
for i in range(j - 1, j - k - 1, -1):
perm[i] = perm[i - 1]
perm[j - k - 1] = j - 1
else:
for i in range(j - 1, k, -1):
perm[i] = perm[i - 1]
perm[k] = j - 1
r2 = r1
return cls._af_new(perm)
def next_trotterjohnson(self):
"""
Returns the next permutation in Trotter-Johnson order.
If self is the last permutation it returns None.
See [4] section 2.4. If it is desired to generate all such
permutations, they can be generated in order more quickly
with the ``generate_bell`` function.
Examples
========
>>> from sympy.combinatorics.permutations import Permutation
>>> Permutation.print_cyclic = False
>>> p = Permutation([3, 0, 2, 1])
>>> p.rank_trotterjohnson()
4
>>> p = p.next_trotterjohnson(); p
Permutation([0, 3, 2, 1])
>>> p.rank_trotterjohnson()
5
See Also
========
rank_trotterjohnson, unrank_trotterjohnson, sympy.utilities.iterables.generate_bell
"""
pi = self.array_form[:]
n = len(pi)
st = 0
rho = pi[:]
done = False
m = n-1
while m > 0 and not done:
d = rho.index(m)
for i in range(d, m):
rho[i] = rho[i + 1]
par = _af_parity(rho[:m])
if par == 1:
if d == m:
m -= 1
else:
pi[st + d], pi[st + d + 1] = pi[st + d + 1], pi[st + d]
done = True
else:
if d == 0:
m -= 1
st += 1
else:
pi[st + d], pi[st + d - 1] = pi[st + d - 1], pi[st + d]
done = True
if m == 0:
return None
return self._af_new(pi)
def get_precedence_matrix(self):
"""
Gets the precedence matrix. This is used for computing the
distance between two permutations.
Examples
========
>>> from sympy.combinatorics.permutations import Permutation
>>> Permutation.print_cyclic = False
>>> p = Permutation.josephus(3, 6, 1)
>>> p
Permutation([2, 5, 3, 1, 4, 0])
>>> p.get_precedence_matrix()
Matrix([
[0, 0, 0, 0, 0, 0],
[1, 0, 0, 0, 1, 0],
[1, 1, 0, 1, 1, 1],
[1, 1, 0, 0, 1, 0],
[1, 0, 0, 0, 0, 0],
[1, 1, 0, 1, 1, 0]])
See Also
========
get_precedence_distance, get_adjacency_matrix, get_adjacency_distance
"""
m = zeros(self.size)
perm = self.array_form
for i in range(m.rows):
for j in range(i + 1, m.cols):
m[perm[i], perm[j]] = 1
return m
def get_precedence_distance(self, other):
"""
Computes the precedence distance between two permutations.
Suppose p and p' represent n jobs. The precedence metric
counts the number of times a job j is preceded by job i
in both p and p'. This metric is commutative.
Examples
========
>>> from sympy.combinatorics.permutations import Permutation
>>> p = Permutation([2, 0, 4, 3, 1])
>>> q = Permutation([3, 1, 2, 4, 0])
>>> p.get_precedence_distance(q)
7
>>> q.get_precedence_distance(p)
7
See Also
========
get_precedence_matrix, get_adjacency_matrix, get_adjacency_distance
"""
if self.size != other.size:
raise ValueError("The permutations must be of equal size.")
self_prec_mat = self.get_precedence_matrix()
other_prec_mat = other.get_precedence_matrix()
n_prec = 0
for i in range(self.size):
for j in range(self.size):
if i == j:
continue
if self_prec_mat[i, j] * other_prec_mat[i, j] == 1:
n_prec += 1
d = self.size * (self.size - 1)//2 - n_prec
return d
def get_adjacency_matrix(self):
"""
Computes the adjacency matrix of a permutation.
If job i is adjacent to job j in a permutation p
then we set m[i, j] = 1 where m is the adjacency
matrix of p.
Examples
========
>>> from sympy.combinatorics.permutations import Permutation
>>> p = Permutation.josephus(3, 6, 1)
>>> p.get_adjacency_matrix()
Matrix([
[0, 0, 0, 0, 0, 0],
[0, 0, 0, 0, 1, 0],
[0, 0, 0, 0, 0, 1],
[0, 1, 0, 0, 0, 0],
[1, 0, 0, 0, 0, 0],
[0, 0, 0, 1, 0, 0]])
>>> q = Permutation([0, 1, 2, 3])
>>> q.get_adjacency_matrix()
Matrix([
[0, 1, 0, 0],
[0, 0, 1, 0],
[0, 0, 0, 1],
[0, 0, 0, 0]])
See Also
========
get_precedence_matrix, get_precedence_distance, get_adjacency_distance
"""
m = zeros(self.size)
perm = self.array_form
for i in range(self.size - 1):
m[perm[i], perm[i + 1]] = 1
return m
def get_adjacency_distance(self, other):
"""
Computes the adjacency distance between two permutations.
This metric counts the number of times a pair i,j of jobs is
adjacent in both p and p'. If n_adj is this quantity then
the adjacency distance is n - n_adj - 1 [1]
[1] Reeves, Colin R. Landscapes, Operators and Heuristic search, Annals
of Operational Research, 86, pp 473-490. (1999)
Examples
========
>>> from sympy.combinatorics.permutations import Permutation
>>> p = Permutation([0, 3, 1, 2, 4])
>>> q = Permutation.josephus(4, 5, 2)
>>> p.get_adjacency_distance(q)
3
>>> r = Permutation([0, 2, 1, 4, 3])
>>> p.get_adjacency_distance(r)
4
See Also
========
get_precedence_matrix, get_precedence_distance, get_adjacency_matrix
"""
if self.size != other.size:
raise ValueError("The permutations must be of the same size.")
self_adj_mat = self.get_adjacency_matrix()
other_adj_mat = other.get_adjacency_matrix()
n_adj = 0
for i in range(self.size):
for j in range(self.size):
if i == j:
continue
if self_adj_mat[i, j] * other_adj_mat[i, j] == 1:
n_adj += 1
d = self.size - n_adj - 1
return d
def get_positional_distance(self, other):
"""
Computes the positional distance between two permutations.
Examples
========
>>> from sympy.combinatorics.permutations import Permutation
>>> p = Permutation([0, 3, 1, 2, 4])
>>> q = Permutation.josephus(4, 5, 2)
>>> r = Permutation([3, 1, 4, 0, 2])
>>> p.get_positional_distance(q)
12
>>> p.get_positional_distance(r)
12
See Also
========
get_precedence_distance, get_adjacency_distance
"""
a = self.array_form
b = other.array_form
if len(a) != len(b):
raise ValueError("The permutations must be of the same size.")
return sum([abs(a[i] - b[i]) for i in range(len(a))])
@classmethod
def josephus(cls, m, n, s=1):
"""Return as a permutation the shuffling of range(n) using the Josephus
scheme in which every m-th item is selected until all have been chosen.
The returned permutation has elements listed by the order in which they
were selected.
The parameter ``s`` stops the selection process when there are ``s``
items remaining and these are selected by continuing the selection,
counting by 1 rather than by ``m``.
Consider selecting every 3rd item from 6 until only 2 remain::
choices chosen
======== ======
012345
01 345 2
01 34 25
01 4 253
0 4 2531
0 25314
253140
Examples
========
>>> from sympy.combinatorics import Permutation
>>> Permutation.josephus(3, 6, 2).array_form
[2, 5, 3, 1, 4, 0]
References
==========
.. [1] https://en.wikipedia.org/wiki/Flavius_Josephus
.. [2] https://en.wikipedia.org/wiki/Josephus_problem
.. [3] http://www.wou.edu/~burtonl/josephus.html
"""
from collections import deque
m -= 1
Q = deque(list(range(n)))
perm = []
while len(Q) > max(s, 1):
for dp in range(m):
Q.append(Q.popleft())
perm.append(Q.popleft())
perm.extend(list(Q))
return cls(perm)
@classmethod
def from_inversion_vector(cls, inversion):
"""
Calculates the permutation from the inversion vector.
Examples
========
>>> from sympy.combinatorics.permutations import Permutation
>>> Permutation.print_cyclic = False
>>> Permutation.from_inversion_vector([3, 2, 1, 0, 0])
Permutation([3, 2, 1, 0, 4, 5])
"""
size = len(inversion)
N = list(range(size + 1))
perm = []
try:
for k in range(size):
val = N[inversion[k]]
perm.append(val)
N.remove(val)
except IndexError:
raise ValueError("The inversion vector is not valid.")
perm.extend(N)
return cls._af_new(perm)
@classmethod
def random(cls, n):
"""
Generates a random permutation of length ``n``.
Uses the underlying Python pseudo-random number generator.
Examples
========
>>> from sympy.combinatorics.permutations import Permutation
>>> Permutation.random(2) in (Permutation([1, 0]), Permutation([0, 1]))
True
"""
perm_array = list(range(n))
random.shuffle(perm_array)
return cls._af_new(perm_array)
@classmethod
def unrank_lex(cls, size, rank):
"""
Lexicographic permutation unranking.
Examples
========
>>> from sympy.combinatorics.permutations import Permutation
>>> Permutation.print_cyclic = False
>>> a = Permutation.unrank_lex(5, 10)
>>> a.rank()
10
>>> a
Permutation([0, 2, 4, 1, 3])
See Also
========
rank, next_lex
"""
perm_array = [0] * size
psize = 1
for i in range(size):
new_psize = psize*(i + 1)
d = (rank % new_psize) // psize
rank -= d*psize
perm_array[size - i - 1] = d
for j in range(size - i, size):
if perm_array[j] > d - 1:
perm_array[j] += 1
psize = new_psize
return cls._af_new(perm_array)
# global flag to control how permutations are printed
# when True, Permutation([0, 2, 1, 3]) -> Cycle(1, 2)
# when False, Permutation([0, 2, 1, 3]) -> Permutation([0, 2, 1])
print_cyclic = True
def _merge(arr, temp, left, mid, right):
"""
Merges two sorted arrays and calculates the inversion count.
Helper function for calculating inversions. This method is
for internal use only.
"""
i = k = left
j = mid
inv_count = 0
while i < mid and j <= right:
if arr[i] < arr[j]:
temp[k] = arr[i]
k += 1
i += 1
else:
temp[k] = arr[j]
k += 1
j += 1
inv_count += (mid -i)
while i < mid:
temp[k] = arr[i]
k += 1
i += 1
if j <= right:
k += right - j + 1
j += right - j + 1
arr[left:k + 1] = temp[left:k + 1]
else:
arr[left:right + 1] = temp[left:right + 1]
return inv_count
Perm = Permutation
_af_new = Perm._af_new
|
b9136e4baae76e2a500c6c62c8aab048ceacd1090c1d5423b910fe1d1ccd6ef5
|
from __future__ import print_function, division
from itertools import combinations
from sympy.combinatorics.graycode import GrayCode
from sympy.core import Basic
from sympy.core.compatibility import range
class Subset(Basic):
"""
Represents a basic subset object.
We generate subsets using essentially two techniques,
binary enumeration and lexicographic enumeration.
The Subset class takes two arguments, the first one
describes the initial subset to consider and the second
describes the superset.
Examples
========
>>> from sympy.combinatorics.subsets import Subset
>>> a = Subset(['c', 'd'], ['a', 'b', 'c', 'd'])
>>> a.next_binary().subset
['b']
>>> a.prev_binary().subset
['c']
"""
_rank_binary = None
_rank_lex = None
_rank_graycode = None
_subset = None
_superset = None
def __new__(cls, subset, superset):
"""
Default constructor.
It takes the subset and its superset as its parameters.
Examples
========
>>> from sympy.combinatorics.subsets import Subset
>>> a = Subset(['c', 'd'], ['a', 'b', 'c', 'd'])
>>> a.subset
['c', 'd']
>>> a.superset
['a', 'b', 'c', 'd']
>>> a.size
2
"""
if len(subset) > len(superset):
raise ValueError('Invalid arguments have been provided. The superset must be larger than the subset.')
for elem in subset:
if elem not in superset:
raise ValueError('The superset provided is invalid as it does not contain the element %i' % elem)
obj = Basic.__new__(cls)
obj._subset = subset
obj._superset = superset
return obj
def iterate_binary(self, k):
"""
This is a helper function. It iterates over the
binary subsets by k steps. This variable can be
both positive or negative.
Examples
========
>>> from sympy.combinatorics.subsets import Subset
>>> a = Subset(['c', 'd'], ['a', 'b', 'c', 'd'])
>>> a.iterate_binary(-2).subset
['d']
>>> a = Subset(['a', 'b', 'c'], ['a', 'b', 'c', 'd'])
>>> a.iterate_binary(2).subset
[]
See Also
========
next_binary, prev_binary
"""
bin_list = Subset.bitlist_from_subset(self.subset, self.superset)
n = (int(''.join(bin_list), 2) + k) % 2**self.superset_size
bits = bin(n)[2:].rjust(self.superset_size, '0')
return Subset.subset_from_bitlist(self.superset, bits)
def next_binary(self):
"""
Generates the next binary ordered subset.
Examples
========
>>> from sympy.combinatorics.subsets import Subset
>>> a = Subset(['c', 'd'], ['a', 'b', 'c', 'd'])
>>> a.next_binary().subset
['b']
>>> a = Subset(['a', 'b', 'c', 'd'], ['a', 'b', 'c', 'd'])
>>> a.next_binary().subset
[]
See Also
========
prev_binary, iterate_binary
"""
return self.iterate_binary(1)
def prev_binary(self):
"""
Generates the previous binary ordered subset.
Examples
========
>>> from sympy.combinatorics.subsets import Subset
>>> a = Subset([], ['a', 'b', 'c', 'd'])
>>> a.prev_binary().subset
['a', 'b', 'c', 'd']
>>> a = Subset(['c', 'd'], ['a', 'b', 'c', 'd'])
>>> a.prev_binary().subset
['c']
See Also
========
next_binary, iterate_binary
"""
return self.iterate_binary(-1)
def next_lexicographic(self):
"""
Generates the next lexicographically ordered subset.
Examples
========
>>> from sympy.combinatorics.subsets import Subset
>>> a = Subset(['c', 'd'], ['a', 'b', 'c', 'd'])
>>> a.next_lexicographic().subset
['d']
>>> a = Subset(['d'], ['a', 'b', 'c', 'd'])
>>> a.next_lexicographic().subset
[]
See Also
========
prev_lexicographic
"""
i = self.superset_size - 1
indices = Subset.subset_indices(self.subset, self.superset)
if i in indices:
if i - 1 in indices:
indices.remove(i - 1)
else:
indices.remove(i)
i = i - 1
while not i in indices and i >= 0:
i = i - 1
if i >= 0:
indices.remove(i)
indices.append(i+1)
else:
while i not in indices and i >= 0:
i = i - 1
indices.append(i + 1)
ret_set = []
super_set = self.superset
for i in indices:
ret_set.append(super_set[i])
return Subset(ret_set, super_set)
def prev_lexicographic(self):
"""
Generates the previous lexicographically ordered subset.
Examples
========
>>> from sympy.combinatorics.subsets import Subset
>>> a = Subset([], ['a', 'b', 'c', 'd'])
>>> a.prev_lexicographic().subset
['d']
>>> a = Subset(['c','d'], ['a', 'b', 'c', 'd'])
>>> a.prev_lexicographic().subset
['c']
See Also
========
next_lexicographic
"""
i = self.superset_size - 1
indices = Subset.subset_indices(self.subset, self.superset)
while i not in indices and i >= 0:
i = i - 1
if i - 1 in indices or i == 0:
indices.remove(i)
else:
if i >= 0:
indices.remove(i)
indices.append(i - 1)
indices.append(self.superset_size - 1)
ret_set = []
super_set = self.superset
for i in indices:
ret_set.append(super_set[i])
return Subset(ret_set, super_set)
def iterate_graycode(self, k):
"""
Helper function used for prev_gray and next_gray.
It performs k step overs to get the respective Gray codes.
Examples
========
>>> from sympy.combinatorics.subsets import Subset
>>> a = Subset([1, 2, 3], [1, 2, 3, 4])
>>> a.iterate_graycode(3).subset
[1, 4]
>>> a.iterate_graycode(-2).subset
[1, 2, 4]
See Also
========
next_gray, prev_gray
"""
unranked_code = GrayCode.unrank(self.superset_size,
(self.rank_gray + k) % self.cardinality)
return Subset.subset_from_bitlist(self.superset,
unranked_code)
def next_gray(self):
"""
Generates the next Gray code ordered subset.
Examples
========
>>> from sympy.combinatorics.subsets import Subset
>>> a = Subset([1, 2, 3], [1, 2, 3, 4])
>>> a.next_gray().subset
[1, 3]
See Also
========
iterate_graycode, prev_gray
"""
return self.iterate_graycode(1)
def prev_gray(self):
"""
Generates the previous Gray code ordered subset.
Examples
========
>>> from sympy.combinatorics.subsets import Subset
>>> a = Subset([2, 3, 4], [1, 2, 3, 4, 5])
>>> a.prev_gray().subset
[2, 3, 4, 5]
See Also
========
iterate_graycode, next_gray
"""
return self.iterate_graycode(-1)
@property
def rank_binary(self):
"""
Computes the binary ordered rank.
Examples
========
>>> from sympy.combinatorics.subsets import Subset
>>> a = Subset([], ['a','b','c','d'])
>>> a.rank_binary
0
>>> a = Subset(['c', 'd'], ['a', 'b', 'c', 'd'])
>>> a.rank_binary
3
See Also
========
iterate_binary, unrank_binary
"""
if self._rank_binary is None:
self._rank_binary = int("".join(
Subset.bitlist_from_subset(self.subset,
self.superset)), 2)
return self._rank_binary
@property
def rank_lexicographic(self):
"""
Computes the lexicographic ranking of the subset.
Examples
========
>>> from sympy.combinatorics.subsets import Subset
>>> a = Subset(['c', 'd'], ['a', 'b', 'c', 'd'])
>>> a.rank_lexicographic
14
>>> a = Subset([2, 4, 5], [1, 2, 3, 4, 5, 6])
>>> a.rank_lexicographic
43
"""
if self._rank_lex is None:
def _ranklex(self, subset_index, i, n):
if subset_index == [] or i > n:
return 0
if i in subset_index:
subset_index.remove(i)
return 1 + _ranklex(self, subset_index, i + 1, n)
return 2**(n - i - 1) + _ranklex(self, subset_index, i + 1, n)
indices = Subset.subset_indices(self.subset, self.superset)
self._rank_lex = _ranklex(self, indices, 0, self.superset_size)
return self._rank_lex
@property
def rank_gray(self):
"""
Computes the Gray code ranking of the subset.
Examples
========
>>> from sympy.combinatorics.subsets import Subset
>>> a = Subset(['c','d'], ['a','b','c','d'])
>>> a.rank_gray
2
>>> a = Subset([2, 4, 5], [1, 2, 3, 4, 5, 6])
>>> a.rank_gray
27
See Also
========
iterate_graycode, unrank_gray
"""
if self._rank_graycode is None:
bits = Subset.bitlist_from_subset(self.subset, self.superset)
self._rank_graycode = GrayCode(len(bits), start=bits).rank
return self._rank_graycode
@property
def subset(self):
"""
Gets the subset represented by the current instance.
Examples
========
>>> from sympy.combinatorics.subsets import Subset
>>> a = Subset(['c', 'd'], ['a', 'b', 'c', 'd'])
>>> a.subset
['c', 'd']
See Also
========
superset, size, superset_size, cardinality
"""
return self._subset
@property
def size(self):
"""
Gets the size of the subset.
Examples
========
>>> from sympy.combinatorics.subsets import Subset
>>> a = Subset(['c', 'd'], ['a', 'b', 'c', 'd'])
>>> a.size
2
See Also
========
subset, superset, superset_size, cardinality
"""
return len(self.subset)
@property
def superset(self):
"""
Gets the superset of the subset.
Examples
========
>>> from sympy.combinatorics.subsets import Subset
>>> a = Subset(['c', 'd'], ['a', 'b', 'c', 'd'])
>>> a.superset
['a', 'b', 'c', 'd']
See Also
========
subset, size, superset_size, cardinality
"""
return self._superset
@property
def superset_size(self):
"""
Returns the size of the superset.
Examples
========
>>> from sympy.combinatorics.subsets import Subset
>>> a = Subset(['c', 'd'], ['a', 'b', 'c', 'd'])
>>> a.superset_size
4
See Also
========
subset, superset, size, cardinality
"""
return len(self.superset)
@property
def cardinality(self):
"""
Returns the number of all possible subsets.
Examples
========
>>> from sympy.combinatorics.subsets import Subset
>>> a = Subset(['c', 'd'], ['a', 'b', 'c', 'd'])
>>> a.cardinality
16
See Also
========
subset, superset, size, superset_size
"""
return 2**(self.superset_size)
@classmethod
def subset_from_bitlist(self, super_set, bitlist):
"""
Gets the subset defined by the bitlist.
Examples
========
>>> from sympy.combinatorics.subsets import Subset
>>> Subset.subset_from_bitlist(['a', 'b', 'c', 'd'], '0011').subset
['c', 'd']
See Also
========
bitlist_from_subset
"""
if len(super_set) != len(bitlist):
raise ValueError("The sizes of the lists are not equal")
ret_set = []
for i in range(len(bitlist)):
if bitlist[i] == '1':
ret_set.append(super_set[i])
return Subset(ret_set, super_set)
@classmethod
def bitlist_from_subset(self, subset, superset):
"""
Gets the bitlist corresponding to a subset.
Examples
========
>>> from sympy.combinatorics.subsets import Subset
>>> Subset.bitlist_from_subset(['c', 'd'], ['a', 'b', 'c', 'd'])
'0011'
See Also
========
subset_from_bitlist
"""
bitlist = ['0'] * len(superset)
if type(subset) is Subset:
subset = subset.args[0]
for i in Subset.subset_indices(subset, superset):
bitlist[i] = '1'
return ''.join(bitlist)
@classmethod
def unrank_binary(self, rank, superset):
"""
Gets the binary ordered subset of the specified rank.
Examples
========
>>> from sympy.combinatorics.subsets import Subset
>>> Subset.unrank_binary(4, ['a', 'b', 'c', 'd']).subset
['b']
See Also
========
iterate_binary, rank_binary
"""
bits = bin(rank)[2:].rjust(len(superset), '0')
return Subset.subset_from_bitlist(superset, bits)
@classmethod
def unrank_gray(self, rank, superset):
"""
Gets the Gray code ordered subset of the specified rank.
Examples
========
>>> from sympy.combinatorics.subsets import Subset
>>> Subset.unrank_gray(4, ['a', 'b', 'c']).subset
['a', 'b']
>>> Subset.unrank_gray(0, ['a', 'b', 'c']).subset
[]
See Also
========
iterate_graycode, rank_gray
"""
graycode_bitlist = GrayCode.unrank(len(superset), rank)
return Subset.subset_from_bitlist(superset, graycode_bitlist)
@classmethod
def subset_indices(self, subset, superset):
"""Return indices of subset in superset in a list; the list is empty
if all elements of subset are not in superset.
Examples
========
>>> from sympy.combinatorics import Subset
>>> superset = [1, 3, 2, 5, 4]
>>> Subset.subset_indices([3, 2, 1], superset)
[1, 2, 0]
>>> Subset.subset_indices([1, 6], superset)
[]
>>> Subset.subset_indices([], superset)
[]
"""
a, b = superset, subset
sb = set(b)
d = {}
for i, ai in enumerate(a):
if ai in sb:
d[ai] = i
sb.remove(ai)
if not sb:
break
else:
return list()
return [d[bi] for bi in b]
def ksubsets(superset, k):
"""
Finds the subsets of size k in lexicographic order.
This uses the itertools generator.
Examples
========
>>> from sympy.combinatorics.subsets import ksubsets
>>> list(ksubsets([1, 2, 3], 2))
[(1, 2), (1, 3), (2, 3)]
>>> list(ksubsets([1, 2, 3, 4, 5], 2))
[(1, 2), (1, 3), (1, 4), (1, 5), (2, 3), (2, 4), \
(2, 5), (3, 4), (3, 5), (4, 5)]
See Also
========
class:Subset
"""
return combinations(superset, k)
|
8e4f1e4098c2b12baa344c4ac435b2c0cc6216d0789da92220684f49224940ca
|
from __future__ import print_function, division
from sympy.combinatorics.perm_groups import PermutationGroup
from sympy.combinatorics.permutations import Permutation
from sympy.core.compatibility import range
from sympy.utilities.iterables import uniq
_af_new = Permutation._af_new
def DirectProduct(*groups):
"""
Returns the direct product of several groups as a permutation group.
This is implemented much like the __mul__ procedure for taking the direct
product of two permutation groups, but the idea of shifting the
generators is realized in the case of an arbitrary number of groups.
A call to DirectProduct(G1, G2, ..., Gn) is generally expected to be faster
than a call to G1*G2*...*Gn (and thus the need for this algorithm).
Examples
========
>>> from sympy.combinatorics.group_constructs import DirectProduct
>>> from sympy.combinatorics.named_groups import CyclicGroup
>>> C = CyclicGroup(4)
>>> G = DirectProduct(C, C, C)
>>> G.order()
64
See Also
========
__mul__
"""
degrees = []
gens_count = []
total_degree = 0
total_gens = 0
for group in groups:
current_deg = group.degree
current_num_gens = len(group.generators)
degrees.append(current_deg)
total_degree += current_deg
gens_count.append(current_num_gens)
total_gens += current_num_gens
array_gens = []
for i in range(total_gens):
array_gens.append(list(range(total_degree)))
current_gen = 0
current_deg = 0
for i in range(len(gens_count)):
for j in range(current_gen, current_gen + gens_count[i]):
gen = ((groups[i].generators)[j - current_gen]).array_form
array_gens[j][current_deg:current_deg + degrees[i]] = \
[x + current_deg for x in gen]
current_gen += gens_count[i]
current_deg += degrees[i]
perm_gens = list(uniq([_af_new(list(a)) for a in array_gens]))
return PermutationGroup(perm_gens, dups=False)
|
b021e51ca72e4f0711133389acbb78f47bc75dab9c75adcfc3e4403adfaa1e5b
|
# -*- coding: utf-8 -*-
from __future__ import print_function, division
from sympy.core import S
from sympy.core.compatibility import is_sequence, as_int, string_types
from sympy.core.expr import Expr
from sympy.core.symbol import Symbol, symbols as _symbols
from sympy.core.sympify import CantSympify
from sympy.printing.defaults import DefaultPrinting
from sympy.utilities import public
from sympy.utilities.iterables import flatten
from sympy.utilities.magic import pollute
@public
def free_group(symbols):
"""Construct a free group returning ``(FreeGroup, (f_0, f_1, ..., f_(n-1))``.
Parameters
==========
symbols : str, Symbol/Expr or sequence of str, Symbol/Expr (may be empty)
Examples
========
>>> from sympy.combinatorics.free_groups import free_group
>>> F, x, y, z = free_group("x, y, z")
>>> F
<free group on the generators (x, y, z)>
>>> x**2*y**-1
x**2*y**-1
>>> type(_)
<class 'sympy.combinatorics.free_groups.FreeGroupElement'>
"""
_free_group = FreeGroup(symbols)
return (_free_group,) + tuple(_free_group.generators)
@public
def xfree_group(symbols):
"""Construct a free group returning ``(FreeGroup, (f_0, f_1, ..., f_(n-1)))``.
Parameters
==========
symbols : str, Symbol/Expr or sequence of str, Symbol/Expr (may be empty)
Examples
========
>>> from sympy.combinatorics.free_groups import xfree_group
>>> F, (x, y, z) = xfree_group("x, y, z")
>>> F
<free group on the generators (x, y, z)>
>>> y**2*x**-2*z**-1
y**2*x**-2*z**-1
>>> type(_)
<class 'sympy.combinatorics.free_groups.FreeGroupElement'>
"""
_free_group = FreeGroup(symbols)
return (_free_group, _free_group.generators)
@public
def vfree_group(symbols):
"""Construct a free group and inject ``f_0, f_1, ..., f_(n-1)`` as symbols
into the global namespace.
Parameters
==========
symbols : str, Symbol/Expr or sequence of str, Symbol/Expr (may be empty)
Examples
========
>>> from sympy.combinatorics.free_groups import vfree_group
>>> vfree_group("x, y, z")
<free group on the generators (x, y, z)>
>>> x**2*y**-2*z
x**2*y**-2*z
>>> type(_)
<class 'sympy.combinatorics.free_groups.FreeGroupElement'>
"""
_free_group = FreeGroup(symbols)
pollute([sym.name for sym in _free_group.symbols], _free_group.generators)
return _free_group
def _parse_symbols(symbols):
if not symbols:
return tuple()
if isinstance(symbols, string_types):
return _symbols(symbols, seq=True)
elif isinstance(symbols, Expr or FreeGroupElement):
return (symbols,)
elif is_sequence(symbols):
if all(isinstance(s, string_types) for s in symbols):
return _symbols(symbols)
elif all(isinstance(s, Expr) for s in symbols):
return symbols
raise ValueError("The type of `symbols` must be one of the following: "
"a str, Symbol/Expr or a sequence of "
"one of these types")
##############################################################################
# FREE GROUP #
##############################################################################
_free_group_cache = {}
class FreeGroup(DefaultPrinting):
"""
Free group with finite or infinite number of generators. Its input API
is that of a str, Symbol/Expr or a sequence of one of
these types (which may be empty)
See Also
========
sympy.polys.rings.PolyRing
References
==========
.. [1] http://www.gap-system.org/Manuals/doc/ref/chap37.html
.. [2] https://en.wikipedia.org/wiki/Free_group
"""
is_associative = True
is_group = True
is_FreeGroup = True
is_PermutationGroup = False
relators = tuple()
def __new__(cls, symbols):
symbols = tuple(_parse_symbols(symbols))
rank = len(symbols)
_hash = hash((cls.__name__, symbols, rank))
obj = _free_group_cache.get(_hash)
if obj is None:
obj = object.__new__(cls)
obj._hash = _hash
obj._rank = rank
# dtype method is used to create new instances of FreeGroupElement
obj.dtype = type("FreeGroupElement", (FreeGroupElement,), {"group": obj})
obj.symbols = symbols
obj.generators = obj._generators()
obj._gens_set = set(obj.generators)
for symbol, generator in zip(obj.symbols, obj.generators):
if isinstance(symbol, Symbol):
name = symbol.name
if hasattr(obj, name):
setattr(obj, name, generator)
_free_group_cache[_hash] = obj
return obj
def _generators(group):
"""Returns the generators of the FreeGroup.
Examples
========
>>> from sympy.combinatorics.free_groups import free_group
>>> F, x, y, z = free_group("x, y, z")
>>> F.generators
(x, y, z)
"""
gens = []
for sym in group.symbols:
elm = ((sym, 1),)
gens.append(group.dtype(elm))
return tuple(gens)
def clone(self, symbols=None):
return self.__class__(symbols or self.symbols)
def __contains__(self, i):
"""Return True if ``i`` is contained in FreeGroup."""
if not isinstance(i, FreeGroupElement):
return False
group = i.group
return self == group
def __hash__(self):
return self._hash
def __len__(self):
return self.rank
def __str__(self):
if self.rank > 30:
str_form = "<free group with %s generators>" % self.rank
else:
str_form = "<free group on the generators "
gens = self.generators
str_form += str(gens) + ">"
return str_form
__repr__ = __str__
def __getitem__(self, index):
symbols = self.symbols[index]
return self.clone(symbols=symbols)
def __eq__(self, other):
"""No ``FreeGroup`` is equal to any "other" ``FreeGroup``.
"""
return self is other
def index(self, gen):
"""Return the index of the generator `gen` from ``(f_0, ..., f_(n-1))``.
Examples
========
>>> from sympy.combinatorics.free_groups import free_group
>>> F, x, y = free_group("x, y")
>>> F.index(y)
1
>>> F.index(x)
0
"""
if isinstance(gen, self.dtype):
return self.generators.index(gen)
else:
raise ValueError("expected a generator of Free Group %s, got %s" % (self, gen))
def order(self):
"""Return the order of the free group.
Examples
========
>>> from sympy.combinatorics.free_groups import free_group
>>> F, x, y = free_group("x, y")
>>> F.order()
oo
>>> free_group("")[0].order()
1
"""
if self.rank == 0:
return 1
else:
return S.Infinity
@property
def elements(self):
"""
Return the elements of the free group.
Examples
========
>>> from sympy.combinatorics.free_groups import free_group
>>> (z,) = free_group("")
>>> z.elements
{<identity>}
"""
if self.rank == 0:
# A set containing Identity element of `FreeGroup` self is returned
return {self.identity}
else:
raise ValueError("Group contains infinitely many elements"
", hence can't be represented")
@property
def rank(self):
r"""
In group theory, the `rank` of a group `G`, denoted `G.rank`,
can refer to the smallest cardinality of a generating set
for G, that is
\operatorname{rank}(G)=\min\{ |X|: X\subseteq G, \left\langle X\right\rangle =G\}.
"""
return self._rank
@property
def is_abelian(self):
"""Returns if the group is Abelian.
Examples
========
>>> from sympy.combinatorics.free_groups import free_group
>>> f, x, y, z = free_group("x y z")
>>> f.is_abelian
False
"""
if self.rank == 0 or self.rank == 1:
return True
else:
return False
@property
def identity(self):
"""Returns the identity element of free group."""
return self.dtype()
def contains(self, g):
"""Tests if Free Group element ``g`` belong to self, ``G``.
In mathematical terms any linear combination of generators
of a Free Group is contained in it.
Examples
========
>>> from sympy.combinatorics.free_groups import free_group
>>> f, x, y, z = free_group("x y z")
>>> f.contains(x**3*y**2)
True
"""
if not isinstance(g, FreeGroupElement):
return False
elif self != g.group:
return False
else:
return True
def center(self):
"""Returns the center of the free group `self`."""
return {self.identity}
############################################################################
# FreeGroupElement #
############################################################################
class FreeGroupElement(CantSympify, DefaultPrinting, tuple):
"""Used to create elements of FreeGroup. It can not be used directly to
create a free group element. It is called by the `dtype` method of the
`FreeGroup` class.
"""
is_assoc_word = True
def new(self, init):
return self.__class__(init)
_hash = None
def __hash__(self):
_hash = self._hash
if _hash is None:
self._hash = _hash = hash((self.group, frozenset(tuple(self))))
return _hash
def copy(self):
return self.new(self)
@property
def is_identity(self):
if self.array_form == tuple():
return True
else:
return False
@property
def array_form(self):
"""
SymPy provides two different internal kinds of representation
of associative words. The first one is called the `array_form`
which is a tuple containing `tuples` as its elements, where the
size of each tuple is two. At the first position the tuple
contains the `symbol-generator`, while at the second position
of tuple contains the exponent of that generator at the position.
Since elements (i.e. words) don't commute, the indexing of tuple
makes that property to stay.
The structure in ``array_form`` of ``FreeGroupElement`` is of form:
``( ( symbol_of_gen , exponent ), ( , ), ... ( , ) )``
Examples
========
>>> from sympy.combinatorics.free_groups import free_group
>>> f, x, y, z = free_group("x y z")
>>> (x*z).array_form
((x, 1), (z, 1))
>>> (x**2*z*y*x**2).array_form
((x, 2), (z, 1), (y, 1), (x, 2))
See Also
========
letter_repr
"""
return tuple(self)
@property
def letter_form(self):
"""
The letter representation of a ``FreeGroupElement`` is a tuple
of generator symbols, with each entry corresponding to a group
generator. Inverses of the generators are represented by
negative generator symbols.
Examples
========
>>> from sympy.combinatorics.free_groups import free_group
>>> f, a, b, c, d = free_group("a b c d")
>>> (a**3).letter_form
(a, a, a)
>>> (a**2*d**-2*a*b**-4).letter_form
(a, a, -d, -d, a, -b, -b, -b, -b)
>>> (a**-2*b**3*d).letter_form
(-a, -a, b, b, b, d)
See Also
========
array_form
"""
return tuple(flatten([(i,)*j if j > 0 else (-i,)*(-j)
for i, j in self.array_form]))
def __getitem__(self, i):
group = self.group
r = self.letter_form[i]
if r.is_Symbol:
return group.dtype(((r, 1),))
else:
return group.dtype(((-r, -1),))
def index(self, gen):
if len(gen) != 1:
raise ValueError()
return (self.letter_form).index(gen.letter_form[0])
@property
def letter_form_elm(self):
"""
"""
group = self.group
r = self.letter_form
return [group.dtype(((elm,1),)) if elm.is_Symbol \
else group.dtype(((-elm,-1),)) for elm in r]
@property
def ext_rep(self):
"""This is called the External Representation of ``FreeGroupElement``
"""
return tuple(flatten(self.array_form))
def __contains__(self, gen):
return gen.array_form[0][0] in tuple([r[0] for r in self.array_form])
def __str__(self):
if self.is_identity:
return "<identity>"
str_form = ""
array_form = self.array_form
for i in range(len(array_form)):
if i == len(array_form) - 1:
if array_form[i][1] == 1:
str_form += str(array_form[i][0])
else:
str_form += str(array_form[i][0]) + \
"**" + str(array_form[i][1])
else:
if array_form[i][1] == 1:
str_form += str(array_form[i][0]) + "*"
else:
str_form += str(array_form[i][0]) + \
"**" + str(array_form[i][1]) + "*"
return str_form
__repr__ = __str__
def __pow__(self, n):
n = as_int(n)
group = self.group
if n == 0:
return group.identity
if n < 0:
n = -n
return (self.inverse())**n
result = self
for i in range(n - 1):
result = result*self
# this method can be improved instead of just returning the
# multiplication of elements
return result
def __mul__(self, other):
"""Returns the product of elements belonging to the same ``FreeGroup``.
Examples
========
>>> from sympy.combinatorics.free_groups import free_group
>>> f, x, y, z = free_group("x y z")
>>> x*y**2*y**-4
x*y**-2
>>> z*y**-2
z*y**-2
>>> x**2*y*y**-1*x**-2
<identity>
"""
group = self.group
if not isinstance(other, group.dtype):
raise TypeError("only FreeGroup elements of same FreeGroup can "
"be multiplied")
if self.is_identity:
return other
if other.is_identity:
return self
r = list(self.array_form + other.array_form)
zero_mul_simp(r, len(self.array_form) - 1)
return group.dtype(tuple(r))
def __div__(self, other):
group = self.group
if not isinstance(other, group.dtype):
raise TypeError("only FreeGroup elements of same FreeGroup can "
"be multiplied")
return self*(other.inverse())
def __rdiv__(self, other):
group = self.group
if not isinstance(other, group.dtype):
raise TypeError("only FreeGroup elements of same FreeGroup can "
"be multiplied")
return other*(self.inverse())
__truediv__ = __div__
__rtruediv__ = __rdiv__
def __add__(self, other):
return NotImplemented
def inverse(self):
"""
Returns the inverse of a ``FreeGroupElement`` element
Examples
========
>>> from sympy.combinatorics.free_groups import free_group
>>> f, x, y, z = free_group("x y z")
>>> x.inverse()
x**-1
>>> (x*y).inverse()
y**-1*x**-1
"""
group = self.group
r = tuple([(i, -j) for i, j in self.array_form[::-1]])
return group.dtype(r)
def order(self):
"""Find the order of a ``FreeGroupElement``.
Examples
========
>>> from sympy.combinatorics.free_groups import free_group
>>> f, x, y = free_group("x y")
>>> (x**2*y*y**-1*x**-2).order()
1
"""
if self.is_identity:
return 1
else:
return S.Infinity
def commutator(self, other):
"""
Return the commutator of `self` and `x`: ``~x*~self*x*self``
"""
group = self.group
if not isinstance(other, group.dtype):
raise ValueError("commutator of only FreeGroupElement of the same "
"FreeGroup exists")
else:
return self.inverse()*other.inverse()*self*other
def eliminate_words(self, words, _all=False, inverse=True):
'''
Replace each subword from the dictionary `words` by words[subword].
If words is a list, replace the words by the identity.
'''
again = True
new = self
if isinstance(words, dict):
while again:
again = False
for sub in words:
prev = new
new = new.eliminate_word(sub, words[sub], _all=_all, inverse=inverse)
if new != prev:
again = True
else:
while again:
again = False
for sub in words:
prev = new
new = new.eliminate_word(sub, _all=_all, inverse=inverse)
if new != prev:
again = True
return new
def eliminate_word(self, gen, by=None, _all=False, inverse=True):
"""
For an associative word `self`, a subword `gen`, and an associative
word `by` (identity by default), return the associative word obtained by
replacing each occurrence of `gen` in `self` by `by`. If `_all = True`,
the occurrences of `gen` that may appear after the first substitution will
also be replaced and so on until no occurrences are found. This might not
always terminate (e.g. `(x).eliminate_word(x, x**2, _all=True)`).
Examples
========
>>> from sympy.combinatorics.free_groups import free_group
>>> f, x, y = free_group("x y")
>>> w = x**5*y*x**2*y**-4*x
>>> w.eliminate_word( x, x**2 )
x**10*y*x**4*y**-4*x**2
>>> w.eliminate_word( x, y**-1 )
y**-11
>>> w.eliminate_word(x**5)
y*x**2*y**-4*x
>>> w.eliminate_word(x*y, y)
x**4*y*x**2*y**-4*x
See Also
========
substituted_word
"""
if by == None:
by = self.group.identity
if self.is_independent(gen) or gen == by:
return self
if gen == self:
return by
if gen**-1 == by:
_all = False
word = self
l = len(gen)
try:
i = word.subword_index(gen)
k = 1
except ValueError:
if not inverse:
return word
try:
i = word.subword_index(gen**-1)
k = -1
except ValueError:
return word
word = word.subword(0, i)*by**k*word.subword(i+l, len(word)).eliminate_word(gen, by)
if _all:
return word.eliminate_word(gen, by, _all=True, inverse=inverse)
else:
return word
def __len__(self):
"""
For an associative word `self`, returns the number of letters in it.
Examples
========
>>> from sympy.combinatorics.free_groups import free_group
>>> f, a, b = free_group("a b")
>>> w = a**5*b*a**2*b**-4*a
>>> len(w)
13
>>> len(a**17)
17
>>> len(w**0)
0
"""
return sum(abs(j) for (i, j) in self)
def __eq__(self, other):
"""
Two associative words are equal if they are words over the
same alphabet and if they are sequences of the same letters.
This is equivalent to saying that the external representations
of the words are equal.
There is no "universal" empty word, every alphabet has its own
empty word.
Examples
========
>>> from sympy.combinatorics.free_groups import free_group
>>> f, swapnil0, swapnil1 = free_group("swapnil0 swapnil1")
>>> f
<free group on the generators (swapnil0, swapnil1)>
>>> g, swap0, swap1 = free_group("swap0 swap1")
>>> g
<free group on the generators (swap0, swap1)>
>>> swapnil0 == swapnil1
False
>>> swapnil0*swapnil1 == swapnil1/swapnil1*swapnil0*swapnil1
True
>>> swapnil0*swapnil1 == swapnil1*swapnil0
False
>>> swapnil1**0 == swap0**0
False
"""
group = self.group
if not isinstance(other, group.dtype):
return False
return tuple.__eq__(self, other)
def __lt__(self, other):
"""
The ordering of associative words is defined by length and
lexicography (this ordering is called short-lex ordering), that
is, shorter words are smaller than longer words, and words of the
same length are compared w.r.t. the lexicographical ordering induced
by the ordering of generators. Generators are sorted according
to the order in which they were created. If the generators are
invertible then each generator `g` is larger than its inverse `g^{-1}`,
and `g^{-1}` is larger than every generator that is smaller than `g`.
Examples
========
>>> from sympy.combinatorics.free_groups import free_group
>>> f, a, b = free_group("a b")
>>> b < a
False
>>> a < a.inverse()
False
"""
group = self.group
if not isinstance(other, group.dtype):
raise TypeError("only FreeGroup elements of same FreeGroup can "
"be compared")
l = len(self)
m = len(other)
# implement lenlex order
if l < m:
return True
elif l > m:
return False
for i in range(l):
a = self[i].array_form[0]
b = other[i].array_form[0]
p = group.symbols.index(a[0])
q = group.symbols.index(b[0])
if p < q:
return True
elif p > q:
return False
elif a[1] < b[1]:
return True
elif a[1] > b[1]:
return False
return False
def __le__(self, other):
return (self == other or self < other)
def __gt__(self, other):
"""
Examples
========
>>> from sympy.combinatorics.free_groups import free_group
>>> f, x, y, z = free_group("x y z")
>>> y**2 > x**2
True
>>> y*z > z*y
False
>>> x > x.inverse()
True
"""
group = self.group
if not isinstance(other, group.dtype):
raise TypeError("only FreeGroup elements of same FreeGroup can "
"be compared")
return not self <= other
def __ge__(self, other):
return not self < other
def exponent_sum(self, gen):
"""
For an associative word `self` and a generator or inverse of generator
`gen`, ``exponent_sum`` returns the number of times `gen` appears in
`self` minus the number of times its inverse appears in `self`. If
neither `gen` nor its inverse occur in `self` then 0 is returned.
Examples
========
>>> from sympy.combinatorics.free_groups import free_group
>>> F, x, y = free_group("x, y")
>>> w = x**2*y**3
>>> w.exponent_sum(x)
2
>>> w.exponent_sum(x**-1)
-2
>>> w = x**2*y**4*x**-3
>>> w.exponent_sum(x)
-1
See Also
========
generator_count
"""
if len(gen) != 1:
raise ValueError("gen must be a generator or inverse of a generator")
s = gen.array_form[0]
return s[1]*sum([i[1] for i in self.array_form if i[0] == s[0]])
def generator_count(self, gen):
"""
For an associative word `self` and a generator `gen`,
``generator_count`` returns the multiplicity of generator
`gen` in `self`.
Examples
========
>>> from sympy.combinatorics.free_groups import free_group
>>> F, x, y = free_group("x, y")
>>> w = x**2*y**3
>>> w.generator_count(x)
2
>>> w = x**2*y**4*x**-3
>>> w.generator_count(x)
5
See Also
========
exponent_sum
"""
if len(gen) != 1 or gen.array_form[0][1] < 0:
raise ValueError("gen must be a generator")
s = gen.array_form[0]
return s[1]*sum([abs(i[1]) for i in self.array_form if i[0] == s[0]])
def subword(self, from_i, to_j, strict=True):
"""
For an associative word `self` and two positive integers `from_i` and
`to_j`, `subword` returns the subword of `self` that begins at position
`from_i` and ends at `to_j - 1`, indexing is done with origin 0.
Examples
========
>>> from sympy.combinatorics.free_groups import free_group
>>> f, a, b = free_group("a b")
>>> w = a**5*b*a**2*b**-4*a
>>> w.subword(2, 6)
a**3*b
"""
group = self.group
if not strict:
from_i = max(from_i, 0)
to_j = min(len(self), to_j)
if from_i < 0 or to_j > len(self):
raise ValueError("`from_i`, `to_j` must be positive and no greater than "
"the length of associative word")
if to_j <= from_i:
return group.identity
else:
letter_form = self.letter_form[from_i: to_j]
array_form = letter_form_to_array_form(letter_form, group)
return group.dtype(array_form)
def subword_index(self, word, start = 0):
'''
Find the index of `word` in `self`.
Examples
========
>>> from sympy.combinatorics.free_groups import free_group
>>> f, a, b = free_group("a b")
>>> w = a**2*b*a*b**3
>>> w.subword_index(a*b*a*b)
1
'''
l = len(word)
self_lf = self.letter_form
word_lf = word.letter_form
index = None
for i in range(start,len(self_lf)-l+1):
if self_lf[i:i+l] == word_lf:
index = i
break
if index is not None:
return index
else:
raise ValueError("The given word is not a subword of self")
def is_dependent(self, word):
"""
Examples
========
>>> from sympy.combinatorics.free_groups import free_group
>>> F, x, y = free_group("x, y")
>>> (x**4*y**-3).is_dependent(x**4*y**-2)
True
>>> (x**2*y**-1).is_dependent(x*y)
False
>>> (x*y**2*x*y**2).is_dependent(x*y**2)
True
>>> (x**12).is_dependent(x**-4)
True
See Also
========
is_independent
"""
try:
return self.subword_index(word) != None
except ValueError:
pass
try:
return self.subword_index(word**-1) != None
except ValueError:
return False
def is_independent(self, word):
"""
See Also
========
is_dependent
"""
return not self.is_dependent(word)
def contains_generators(self):
"""
Examples
========
>>> from sympy.combinatorics.free_groups import free_group
>>> F, x, y, z = free_group("x, y, z")
>>> (x**2*y**-1).contains_generators()
{x, y}
>>> (x**3*z).contains_generators()
{x, z}
"""
group = self.group
gens = set()
for syllable in self.array_form:
gens.add(group.dtype(((syllable[0], 1),)))
return set(gens)
def cyclic_subword(self, from_i, to_j):
group = self.group
l = len(self)
letter_form = self.letter_form
period1 = int(from_i/l)
if from_i >= l:
from_i -= l*period1
to_j -= l*period1
diff = to_j - from_i
word = letter_form[from_i: to_j]
period2 = int(to_j/l) - 1
word += letter_form*period2 + letter_form[:diff-l+from_i-l*period2]
word = letter_form_to_array_form(word, group)
return group.dtype(word)
def cyclic_conjugates(self):
"""Returns a words which are cyclic to the word `self`.
Examples
========
>>> from sympy.combinatorics.free_groups import free_group
>>> F, x, y = free_group("x, y")
>>> w = x*y*x*y*x
>>> w.cyclic_conjugates()
{x*y*x**2*y, x**2*y*x*y, y*x*y*x**2, y*x**2*y*x, x*y*x*y*x}
>>> s = x*y*x**2*y*x
>>> s.cyclic_conjugates()
{x**2*y*x**2*y, y*x**2*y*x**2, x*y*x**2*y*x}
References
==========
http://planetmath.org/cyclicpermutation
"""
return {self.cyclic_subword(i, i+len(self)) for i in range(len(self))}
def is_cyclic_conjugate(self, w):
"""
Checks whether words ``self``, ``w`` are cyclic conjugates.
Examples
========
>>> from sympy.combinatorics.free_groups import free_group
>>> F, x, y = free_group("x, y")
>>> w1 = x**2*y**5
>>> w2 = x*y**5*x
>>> w1.is_cyclic_conjugate(w2)
True
>>> w3 = x**-1*y**5*x**-1
>>> w3.is_cyclic_conjugate(w2)
False
"""
l1 = len(self)
l2 = len(w)
if l1 != l2:
return False
w1 = self.identity_cyclic_reduction()
w2 = w.identity_cyclic_reduction()
letter1 = w1.letter_form
letter2 = w2.letter_form
str1 = ' '.join(map(str, letter1))
str2 = ' '.join(map(str, letter2))
if len(str1) != len(str2):
return False
return str1 in str2 + ' ' + str2
def number_syllables(self):
"""Returns the number of syllables of the associative word `self`.
Examples
========
>>> from sympy.combinatorics.free_groups import free_group
>>> f, swapnil0, swapnil1 = free_group("swapnil0 swapnil1")
>>> (swapnil1**3*swapnil0*swapnil1**-1).number_syllables()
3
"""
return len(self.array_form)
def exponent_syllable(self, i):
"""
Returns the exponent of the `i`-th syllable of the associative word
`self`.
Examples
========
>>> from sympy.combinatorics.free_groups import free_group
>>> f, a, b = free_group("a b")
>>> w = a**5*b*a**2*b**-4*a
>>> w.exponent_syllable( 2 )
2
"""
return self.array_form[i][1]
def generator_syllable(self, i):
"""
Returns the symbol of the generator that is involved in the
i-th syllable of the associative word `self`.
Examples
========
>>> from sympy.combinatorics.free_groups import free_group
>>> f, a, b = free_group("a b")
>>> w = a**5*b*a**2*b**-4*a
>>> w.generator_syllable( 3 )
b
"""
return self.array_form[i][0]
def sub_syllables(self, from_i, to_j):
"""
`sub_syllables` returns the subword of the associative word `self` that
consists of syllables from positions `from_to` to `to_j`, where
`from_to` and `to_j` must be positive integers and indexing is done
with origin 0.
Examples
========
>>> from sympy.combinatorics.free_groups import free_group
>>> f, a, b = free_group("a, b")
>>> w = a**5*b*a**2*b**-4*a
>>> w.sub_syllables(1, 2)
b
>>> w.sub_syllables(3, 3)
<identity>
"""
if not isinstance(from_i, int) or not isinstance(to_j, int):
raise ValueError("both arguments should be integers")
group = self.group
if to_j <= from_i:
return group.identity
else:
r = tuple(self.array_form[from_i: to_j])
return group.dtype(r)
def substituted_word(self, from_i, to_j, by):
"""
Returns the associative word obtained by replacing the subword of
`self` that begins at position `from_i` and ends at position `to_j - 1`
by the associative word `by`. `from_i` and `to_j` must be positive
integers, indexing is done with origin 0. In other words,
`w.substituted_word(w, from_i, to_j, by)` is the product of the three
words: `w.subword(0, from_i)`, `by`, and
`w.subword(to_j len(w))`.
See Also
========
eliminate_word
"""
lw = len(self)
if from_i >= to_j or from_i > lw or to_j > lw:
raise ValueError("values should be within bounds")
# otherwise there are four possibilities
# first if from=1 and to=lw then
if from_i == 0 and to_j == lw:
return by
elif from_i == 0: # second if from_i=1 (and to_j < lw) then
return by*self.subword(to_j, lw)
elif to_j == lw: # third if to_j=1 (and from_i > 1) then
return self.subword(0, from_i)*by
else: # finally
return self.subword(0, from_i)*by*self.subword(to_j, lw)
def is_cyclically_reduced(self):
r"""Returns whether the word is cyclically reduced or not.
A word is cyclically reduced if by forming the cycle of the
word, the word is not reduced, i.e a word w = `a_1 ... a_n`
is called cyclically reduced if `a_1 \ne a_n^{−1}`.
Examples
========
>>> from sympy.combinatorics.free_groups import free_group
>>> F, x, y = free_group("x, y")
>>> (x**2*y**-1*x**-1).is_cyclically_reduced()
False
>>> (y*x**2*y**2).is_cyclically_reduced()
True
"""
if not self:
return True
return self[0] != self[-1]**-1
def identity_cyclic_reduction(self):
"""Return a unique cyclically reduced version of the word.
Examples
========
>>> from sympy.combinatorics.free_groups import free_group
>>> F, x, y = free_group("x, y")
>>> (x**2*y**2*x**-1).identity_cyclic_reduction()
x*y**2
>>> (x**-3*y**-1*x**5).identity_cyclic_reduction()
x**2*y**-1
References
==========
http://planetmath.org/cyclicallyreduced
"""
word = self.copy()
group = self.group
while not word.is_cyclically_reduced():
exp1 = word.exponent_syllable(0)
exp2 = word.exponent_syllable(-1)
r = exp1 + exp2
if r == 0:
rep = word.array_form[1: word.number_syllables() - 1]
else:
rep = ((word.generator_syllable(0), exp1 + exp2),) + \
word.array_form[1: word.number_syllables() - 1]
word = group.dtype(rep)
return word
def cyclic_reduction(self, removed=False):
"""Return a cyclically reduced version of the word. Unlike
`identity_cyclic_reduction`, this will not cyclically permute
the reduced word - just remove the "unreduced" bits on either
side of it. Compare the examples with those of
`identity_cyclic_reduction`.
When `removed` is `True`, return a tuple `(word, r)` where
self `r` is such that before the reduction the word was either
`r*word*r**-1`.
Examples
========
>>> from sympy.combinatorics.free_groups import free_group
>>> F, x, y = free_group("x, y")
>>> (x**2*y**2*x**-1).cyclic_reduction()
x*y**2
>>> (x**-3*y**-1*x**5).cyclic_reduction()
y**-1*x**2
>>> (x**-3*y**-1*x**5).cyclic_reduction(removed=True)
(y**-1*x**2, x**-3)
"""
word = self.copy()
g = self.group.identity
while not word.is_cyclically_reduced():
exp1 = abs(word.exponent_syllable(0))
exp2 = abs(word.exponent_syllable(-1))
exp = min(exp1, exp2)
start = word[0]**abs(exp)
end = word[-1]**abs(exp)
word = start**-1*word*end**-1
g = g*start
if removed:
return word, g
return word
def power_of(self, other):
'''
Check if `self == other**n` for some integer n.
Examples
========
>>> from sympy.combinatorics.free_groups import free_group
>>> F, x, y = free_group("x, y")
>>> ((x*y)**2).power_of(x*y)
True
>>> (x**-3*y**-2*x**3).power_of(x**-3*y*x**3)
True
'''
if self.is_identity:
return True
l = len(other)
if l == 1:
# self has to be a power of one generator
gens = self.contains_generators()
s = other in gens or other**-1 in gens
return len(gens) == 1 and s
# if self is not cyclically reduced and it is a power of other,
# other isn't cyclically reduced and the parts removed during
# their reduction must be equal
reduced, r1 = self.cyclic_reduction(removed=True)
if not r1.is_identity:
other, r2 = other.cyclic_reduction(removed=True)
if r1 == r2:
return reduced.power_of(other)
return False
if len(self) < l or len(self) % l:
return False
prefix = self.subword(0, l)
if prefix == other or prefix**-1 == other:
rest = self.subword(l, len(self))
return rest.power_of(other)
return False
def letter_form_to_array_form(array_form, group):
"""
This method converts a list given with possible repetitions of elements in
it. It returns a new list such that repetitions of consecutive elements is
removed and replace with a tuple element of size two such that the first
index contains `value` and the second index contains the number of
consecutive repetitions of `value`.
"""
a = list(array_form[:])
new_array = []
n = 1
symbols = group.symbols
for i in range(len(a)):
if i == len(a) - 1:
if a[i] == a[i - 1]:
if (-a[i]) in symbols:
new_array.append((-a[i], -n))
else:
new_array.append((a[i], n))
else:
if (-a[i]) in symbols:
new_array.append((-a[i], -1))
else:
new_array.append((a[i], 1))
return new_array
elif a[i] == a[i + 1]:
n += 1
else:
if (-a[i]) in symbols:
new_array.append((-a[i], -n))
else:
new_array.append((a[i], n))
n = 1
def zero_mul_simp(l, index):
"""Used to combine two reduced words."""
while index >=0 and index < len(l) - 1 and l[index][0] == l[index + 1][0]:
exp = l[index][1] + l[index + 1][1]
base = l[index][0]
l[index] = (base, exp)
del l[index + 1]
if l[index][1] == 0:
del l[index]
index -= 1
|
0673529a05f08fb4286baed3999fd7f861e5e25d2a3a38ee0809d7d3ed772ec8
|
from __future__ import print_function, division
from sympy.core.compatibility import range
from sympy.combinatorics.permutations import Permutation, _af_rmul, \
_af_invert, _af_new
from sympy.combinatorics.perm_groups import PermutationGroup, _orbit, \
_orbit_transversal
from sympy.combinatorics.util import _distribute_gens_by_base, \
_orbits_transversals_from_bsgs
"""
References for tensor canonicalization:
[1] R. Portugal "Algorithmic simplification of tensor expressions",
J. Phys. A 32 (1999) 7779-7789
[2] R. Portugal, B.F. Svaiter "Group-theoretic Approach for Symbolic
Tensor Manipulation: I. Free Indices"
arXiv:math-ph/0107031v1
[3] L.R.U. Manssur, R. Portugal "Group-theoretic Approach for Symbolic
Tensor Manipulation: II. Dummy Indices"
arXiv:math-ph/0107032v1
[4] xperm.c part of XPerm written by J. M. Martin-Garcia
http://www.xact.es/index.html
"""
def dummy_sgs(dummies, sym, n):
"""
Return the strong generators for dummy indices
Parameters
==========
dummies : list of dummy indices
`dummies[2k], dummies[2k+1]` are paired indices
sym : symmetry under interchange of contracted dummies::
* None no symmetry
* 0 commuting
* 1 anticommuting
n : number of indices
in base form the dummy indices are always in consecutive positions
Examples
========
>>> from sympy.combinatorics.tensor_can import dummy_sgs
>>> dummy_sgs(list(range(2, 8)), 0, 8)
[[0, 1, 3, 2, 4, 5, 6, 7, 8, 9], [0, 1, 2, 3, 5, 4, 6, 7, 8, 9],
[0, 1, 2, 3, 4, 5, 7, 6, 8, 9], [0, 1, 4, 5, 2, 3, 6, 7, 8, 9],
[0, 1, 2, 3, 6, 7, 4, 5, 8, 9]]
"""
if len(dummies) > n:
raise ValueError("List too large")
res = []
# exchange of contravariant and covariant indices
if sym is not None:
for j in dummies[::2]:
a = list(range(n + 2))
if sym == 1:
a[n] = n + 1
a[n + 1] = n
a[j], a[j + 1] = a[j + 1], a[j]
res.append(a)
# rename dummy indices
for j in dummies[:-3:2]:
a = list(range(n + 2))
a[j:j + 4] = a[j + 2], a[j + 3], a[j], a[j + 1]
res.append(a)
return res
def _min_dummies(dummies, sym, indices):
"""
Return list of minima of the orbits of indices in group of dummies
see `double_coset_can_rep` for the description of `dummies` and `sym`
indices is the initial list of dummy indices
Examples
========
>>> from sympy.combinatorics.tensor_can import _min_dummies
>>> _min_dummies([list(range(2, 8))], [0], list(range(10)))
[0, 1, 2, 2, 2, 2, 2, 2, 8, 9]
"""
num_types = len(sym)
m = []
for dx in dummies:
if dx:
m.append(min(dx))
else:
m.append(None)
res = indices[:]
for i in range(num_types):
for c, i in enumerate(indices):
for j in range(num_types):
if i in dummies[j]:
res[c] = m[j]
break
return res
def _trace_S(s, j, b, S_cosets):
"""
Return the representative h satisfying s[h[b]] == j
If there is not such a representative return None
"""
for h in S_cosets[b]:
if s[h[b]] == j:
return h
return None
def _trace_D(gj, p_i, Dxtrav):
"""
Return the representative h satisfying h[gj] == p_i
If there is not such a representative return None
"""
for h in Dxtrav:
if h[gj] == p_i:
return h
return None
def _dumx_remove(dumx, dumx_flat, p0):
"""
remove p0 from dumx
"""
res = []
for dx in dumx:
if p0 not in dx:
res.append(dx)
continue
k = dx.index(p0)
if k % 2 == 0:
p0_paired = dx[k + 1]
else:
p0_paired = dx[k - 1]
dx.remove(p0)
dx.remove(p0_paired)
dumx_flat.remove(p0)
dumx_flat.remove(p0_paired)
res.append(dx)
def transversal2coset(size, base, transversal):
a = []
j = 0
for i in range(size):
if i in base:
a.append(sorted(transversal[j].values()))
j += 1
else:
a.append([list(range(size))])
j = len(a) - 1
while a[j] == [list(range(size))]:
j -= 1
return a[:j + 1]
def double_coset_can_rep(dummies, sym, b_S, sgens, S_transversals, g):
"""
Butler-Portugal algorithm for tensor canonicalization with dummy indices
Parameters
==========
dummies
list of lists of dummy indices,
one list for each type of index;
the dummy indices are put in order contravariant, covariant
[d0, -d0, d1, -d1, ...].
sym
list of the symmetries of the index metric for each type.
possible symmetries of the metrics
* 0 symmetric
* 1 antisymmetric
* None no symmetry
b_S
base of a minimal slot symmetry BSGS.
sgens
generators of the slot symmetry BSGS.
S_transversals
transversals for the slot BSGS.
g
permutation representing the tensor.
Returns
=======
Return 0 if the tensor is zero, else return the array form of
the permutation representing the canonical form of the tensor.
Notes
=====
A tensor with dummy indices can be represented in a number
of equivalent ways which typically grows exponentially with
the number of indices. To be able to establish if two tensors
with many indices are equal becomes computationally very slow
in absence of an efficient algorithm.
The Butler-Portugal algorithm [3] is an efficient algorithm to
put tensors in canonical form, solving the above problem.
Portugal observed that a tensor can be represented by a permutation,
and that the class of tensors equivalent to it under slot and dummy
symmetries is equivalent to the double coset `D*g*S`
(Note: in this documentation we use the conventions for multiplication
of permutations p, q with (p*q)(i) = p[q[i]] which is opposite
to the one used in the Permutation class)
Using the algorithm by Butler to find a representative of the
double coset one can find a canonical form for the tensor.
To see this correspondence,
let `g` be a permutation in array form; a tensor with indices `ind`
(the indices including both the contravariant and the covariant ones)
can be written as
`t = T(ind[g[0],..., ind[g[n-1]])`,
where `n= len(ind)`;
`g` has size `n + 2`, the last two indices for the sign of the tensor
(trick introduced in [4]).
A slot symmetry transformation `s` is a permutation acting on the slots
`t -> T(ind[(g*s)[0]],..., ind[(g*s)[n-1]])`
A dummy symmetry transformation acts on `ind`
`t -> T(ind[(d*g)[0]],..., ind[(d*g)[n-1]])`
Being interested only in the transformations of the tensor under
these symmetries, one can represent the tensor by `g`, which transforms
as
`g -> d*g*s`, so it belongs to the coset `D*g*S`.
Let us explain the conventions by an example.
Given a tensor `T^{d3 d2 d1}{}_{d1 d2 d3}` with the slot symmetries
`T^{a0 a1 a2 a3 a4 a5} = -T^{a2 a1 a0 a3 a4 a5}`
`T^{a0 a1 a2 a3 a4 a5} = -T^{a4 a1 a2 a3 a0 a5}`
and symmetric metric, find the tensor equivalent to it which
is the lowest under the ordering of indices:
lexicographic ordering `d1, d2, d3` then and contravariant index
before covariant index; that is the canonical form of the tensor.
The canonical form is `-T^{d1 d2 d3}{}_{d1 d2 d3}`
obtained using `T^{a0 a1 a2 a3 a4 a5} = -T^{a2 a1 a0 a3 a4 a5}`.
To convert this problem in the input for this function,
use the following labelling of the index names
(- for covariant for short) `d1, -d1, d2, -d2, d3, -d3`
`T^{d3 d2 d1}{}_{d1 d2 d3}` corresponds to `g = [4, 2, 0, 1, 3, 5, 6, 7]`
where the last two indices are for the sign
`sgens = [Permutation(0, 2)(6, 7), Permutation(0, 4)(6, 7)]`
sgens[0] is the slot symmetry `-(0, 2)`
`T^{a0 a1 a2 a3 a4 a5} = -T^{a2 a1 a0 a3 a4 a5}`
sgens[1] is the slot symmetry `-(0, 4)`
`T^{a0 a1 a2 a3 a4 a5} = -T^{a4 a1 a2 a3 a0 a5}`
The dummy symmetry group D is generated by the strong base generators
`[(0, 1), (2, 3), (4, 5), (0, 1)(2, 3),(2, 3)(4, 5)]`
The dummy symmetry acts from the left
`d = [1, 0, 2, 3, 4, 5, 6, 7]` exchange `d1 -> -d1`
`T^{d3 d2 d1}{}_{d1 d2 d3} == T^{d3 d2}{}_{d1}{}^{d1}{}_{d2 d3}`
`g=[4, 2, 0, 1, 3, 5, 6, 7] -> [4, 2, 1, 0, 3, 5, 6, 7] = _af_rmul(d, g)`
which differs from `_af_rmul(g, d)`.
The slot symmetry acts from the right
`s = [2, 1, 0, 3, 4, 5, 7, 6]` exchanges slots 0 and 2 and changes sign
`T^{d3 d2 d1}{}_{d1 d2 d3} == -T^{d1 d2 d3}{}_{d1 d2 d3}`
`g=[4,2,0,1,3,5,6,7] -> [0, 2, 4, 1, 3, 5, 7, 6] = _af_rmul(g, s)`
Example in which the tensor is zero, same slot symmetries as above:
`T^{d3}{}_{d1,d2}{}^{d1}{}_{d3}{}^{d2}`
`= -T^{d3}{}_{d1,d3}{}^{d1}{}_{d2}{}^{d2}` under slot symmetry `-(2,4)`;
`= T_{d3 d1}{}^{d3}{}^{d1}{}_{d2}{}^{d2}` under slot symmetry `-(0,2)`;
`= T^{d3}{}_{d1 d3}{}^{d1}{}_{d2}{}^{d2}` symmetric metric;
`= 0` since two of these lines have tensors differ only for the sign.
The double coset D*g*S consists of permutations `h = d*g*s` corresponding
to equivalent tensors; if there are two `h` which are the same apart
from the sign, return zero; otherwise
choose as representative the tensor with indices
ordered lexicographically according to `[d1, -d1, d2, -d2, d3, -d3]`
that is `rep = min(D*g*S) = min([d*g*s for d in D for s in S])`
The indices are fixed one by one; first choose the lowest index
for slot 0, then the lowest remaining index for slot 1, etc.
Doing this one obtains a chain of stabilizers
`S -> S_{b0} -> S_{b0,b1} -> ...` and
`D -> D_{p0} -> D_{p0,p1} -> ...`
where `[b0, b1, ...] = range(b)` is a base of the symmetric group;
the strong base `b_S` of S is an ordered sublist of it;
therefore it is sufficient to compute once the
strong base generators of S using the Schreier-Sims algorithm;
the stabilizers of the strong base generators are the
strong base generators of the stabilizer subgroup.
`dbase = [p0, p1, ...]` is not in general in lexicographic order,
so that one must recompute the strong base generators each time;
however this is trivial, there is no need to use the Schreier-Sims
algorithm for D.
The algorithm keeps a TAB of elements `(s_i, d_i, h_i)`
where `h_i = d_i*g*s_i` satisfying `h_i[j] = p_j` for `0 <= j < i`
starting from `s_0 = id, d_0 = id, h_0 = g`.
The equations `h_0[0] = p_0, h_1[1] = p_1,...` are solved in this order,
choosing each time the lowest possible value of p_i
For `j < i`
`d_i*g*s_i*S_{b_0,...,b_{i-1}}*b_j = D_{p_0,...,p_{i-1}}*p_j`
so that for dx in `D_{p_0,...,p_{i-1}}` and sx in
`S_{base[0],...,base[i-1]}` one has `dx*d_i*g*s_i*sx*b_j = p_j`
Search for dx, sx such that this equation holds for `j = i`;
it can be written as `s_i*sx*b_j = J, dx*d_i*g*J = p_j`
`sx*b_j = s_i**-1*J; sx = trace(s_i**-1, S_{b_0,...,b_{i-1}})`
`dx**-1*p_j = d_i*g*J; dx = trace(d_i*g*J, D_{p_0,...,p_{i-1}})`
`s_{i+1} = s_i*trace(s_i**-1*J, S_{b_0,...,b_{i-1}})`
`d_{i+1} = trace(d_i*g*J, D_{p_0,...,p_{i-1}})**-1*d_i`
`h_{i+1}*b_i = d_{i+1}*g*s_{i+1}*b_i = p_i`
`h_n*b_j = p_j` for all j, so that `h_n` is the solution.
Add the found `(s, d, h)` to TAB1.
At the end of the iteration sort TAB1 with respect to the `h`;
if there are two consecutive `h` in TAB1 which differ only for the
sign, the tensor is zero, so return 0;
if there are two consecutive `h` which are equal, keep only one.
Then stabilize the slot generators under `i` and the dummy generators
under `p_i`.
Assign `TAB = TAB1` at the end of the iteration step.
At the end `TAB` contains a unique `(s, d, h)`, since all the slots
of the tensor `h` have been fixed to have the minimum value according
to the symmetries. The algorithm returns `h`.
It is important that the slot BSGS has lexicographic minimal base,
otherwise there is an `i` which does not belong to the slot base
for which `p_i` is fixed by the dummy symmetry only, while `i`
is not invariant from the slot stabilizer, so `p_i` is not in
general the minimal value.
This algorithm differs slightly from the original algorithm [3]:
the canonical form is minimal lexicographically, and
the BSGS has minimal base under lexicographic order.
Equal tensors `h` are eliminated from TAB.
Examples
========
>>> from sympy.combinatorics.permutations import Permutation
>>> from sympy.combinatorics.perm_groups import PermutationGroup
>>> from sympy.combinatorics.tensor_can import double_coset_can_rep, get_transversals
>>> gens = [Permutation(x) for x in [[2, 1, 0, 3, 4, 5, 7, 6], [4, 1, 2, 3, 0, 5, 7, 6]]]
>>> base = [0, 2]
>>> g = Permutation([4, 2, 0, 1, 3, 5, 6, 7])
>>> transversals = get_transversals(base, gens)
>>> double_coset_can_rep([list(range(6))], [0], base, gens, transversals, g)
[0, 1, 2, 3, 4, 5, 7, 6]
>>> g = Permutation([4, 1, 3, 0, 5, 2, 6, 7])
>>> double_coset_can_rep([list(range(6))], [0], base, gens, transversals, g)
0
"""
size = g.size
g = g.array_form
num_dummies = size - 2
indices = list(range(num_dummies))
all_metrics_with_sym = all([_ is not None for _ in sym])
num_types = len(sym)
dumx = dummies[:]
dumx_flat = []
for dx in dumx:
dumx_flat.extend(dx)
b_S = b_S[:]
sgensx = [h._array_form for h in sgens]
if b_S:
S_transversals = transversal2coset(size, b_S, S_transversals)
# strong generating set for D
dsgsx = []
for i in range(num_types):
dsgsx.extend(dummy_sgs(dumx[i], sym[i], num_dummies))
idn = list(range(size))
# TAB = list of entries (s, d, h) where h = _af_rmuln(d,g,s)
# for short, in the following d*g*s means _af_rmuln(d,g,s)
TAB = [(idn, idn, g)]
for i in range(size - 2):
b = i
testb = b in b_S and sgensx
if testb:
sgensx1 = [_af_new(_) for _ in sgensx]
deltab = _orbit(size, sgensx1, b)
else:
deltab = {b}
# p1 = min(IMAGES) = min(Union D_p*h*deltab for h in TAB)
if all_metrics_with_sym:
md = _min_dummies(dumx, sym, indices)
else:
md = [min(_orbit(size, [_af_new(
ddx) for ddx in dsgsx], ii)) for ii in range(size - 2)]
p_i = min([min([md[h[x]] for x in deltab]) for s, d, h in TAB])
dsgsx1 = [_af_new(_) for _ in dsgsx]
Dxtrav = _orbit_transversal(size, dsgsx1, p_i, False, af=True) \
if dsgsx else None
if Dxtrav:
Dxtrav = [_af_invert(x) for x in Dxtrav]
# compute the orbit of p_i
for ii in range(num_types):
if p_i in dumx[ii]:
# the orbit is made by all the indices in dum[ii]
if sym[ii] is not None:
deltap = dumx[ii]
else:
# the orbit is made by all the even indices if p_i
# is even, by all the odd indices if p_i is odd
p_i_index = dumx[ii].index(p_i) % 2
deltap = dumx[ii][p_i_index::2]
break
else:
deltap = [p_i]
TAB1 = []
while TAB:
s, d, h = TAB.pop()
if min([md[h[x]] for x in deltab]) != p_i:
continue
deltab1 = [x for x in deltab if md[h[x]] == p_i]
# NEXT = s*deltab1 intersection (d*g)**-1*deltap
dg = _af_rmul(d, g)
dginv = _af_invert(dg)
sdeltab = [s[x] for x in deltab1]
gdeltap = [dginv[x] for x in deltap]
NEXT = [x for x in sdeltab if x in gdeltap]
# d, s satisfy
# d*g*s*base[i-1] = p_{i-1}; using the stabilizers
# d*g*s*S_{base[0],...,base[i-1]}*base[i-1] =
# D_{p_0,...,p_{i-1}}*p_{i-1}
# so that to find d1, s1 satisfying d1*g*s1*b = p_i
# one can look for dx in D_{p_0,...,p_{i-1}} and
# sx in S_{base[0],...,base[i-1]}
# d1 = dx*d; s1 = s*sx
# d1*g*s1*b = dx*d*g*s*sx*b = p_i
for j in NEXT:
if testb:
# solve s1*b = j with s1 = s*sx for some element sx
# of the stabilizer of ..., base[i-1]
# sx*b = s**-1*j; sx = _trace_S(s, j,...)
# s1 = s*trace_S(s**-1*j,...)
s1 = _trace_S(s, j, b, S_transversals)
if not s1:
continue
else:
s1 = [s[ix] for ix in s1]
else:
s1 = s
# assert s1[b] == j # invariant
# solve d1*g*j = p_i with d1 = dx*d for some element dg
# of the stabilizer of ..., p_{i-1}
# dx**-1*p_i = d*g*j; dx**-1 = trace_D(d*g*j,...)
# d1 = trace_D(d*g*j,...)**-1*d
# to save an inversion in the inner loop; notice we did
# Dxtrav = [perm_af_invert(x) for x in Dxtrav] out of the loop
if Dxtrav:
d1 = _trace_D(dg[j], p_i, Dxtrav)
if not d1:
continue
else:
if p_i != dg[j]:
continue
d1 = idn
assert d1[dg[j]] == p_i # invariant
d1 = [d1[ix] for ix in d]
h1 = [d1[g[ix]] for ix in s1]
# assert h1[b] == p_i # invariant
TAB1.append((s1, d1, h1))
# if TAB contains equal permutations, keep only one of them;
# if TAB contains equal permutations up to the sign, return 0
TAB1.sort(key=lambda x: x[-1])
prev = [0] * size
while TAB1:
s, d, h = TAB1.pop()
if h[:-2] == prev[:-2]:
if h[-1] != prev[-1]:
return 0
else:
TAB.append((s, d, h))
prev = h
# stabilize the SGS
sgensx = [h for h in sgensx if h[b] == b]
if b in b_S:
b_S.remove(b)
_dumx_remove(dumx, dumx_flat, p_i)
dsgsx = []
for i in range(num_types):
dsgsx.extend(dummy_sgs(dumx[i], sym[i], num_dummies))
return TAB[0][-1]
def canonical_free(base, gens, g, num_free):
"""
canonicalization of a tensor with respect to free indices
choosing the minimum with respect to lexicographical ordering
in the free indices
``base``, ``gens`` BSGS for slot permutation group
``g`` permutation representing the tensor
``num_free`` number of free indices
The indices must be ordered with first the free indices
see explanation in double_coset_can_rep
The algorithm is a variation of the one given in [2].
Examples
========
>>> from sympy.combinatorics import Permutation
>>> from sympy.combinatorics.tensor_can import canonical_free
>>> gens = [[1, 0, 2, 3, 5, 4], [2, 3, 0, 1, 4, 5],[0, 1, 3, 2, 5, 4]]
>>> gens = [Permutation(h) for h in gens]
>>> base = [0, 2]
>>> g = Permutation([2, 1, 0, 3, 4, 5])
>>> canonical_free(base, gens, g, 4)
[0, 3, 1, 2, 5, 4]
Consider the product of Riemann tensors
``T = R^{a}_{d0}^{d1,d2}*R_{d2,d1}^{d0,b}``
The order of the indices is ``[a, b, d0, -d0, d1, -d1, d2, -d2]``
The permutation corresponding to the tensor is
``g = [0, 3, 4, 6, 7, 5, 2, 1, 8, 9]``
In particular ``a`` is position ``0``, ``b`` is in position ``9``.
Use the slot symmetries to get `T` is a form which is the minimal
in lexicographic order in the free indices ``a`` and ``b``, e.g.
``-R^{a}_{d0}^{d1,d2}*R^{b,d0}_{d2,d1}`` corresponding to
``[0, 3, 4, 6, 1, 2, 7, 5, 9, 8]``
>>> from sympy.combinatorics.tensor_can import riemann_bsgs, tensor_gens
>>> base, gens = riemann_bsgs
>>> size, sbase, sgens = tensor_gens(base, gens, [[], []], 0)
>>> g = Permutation([0, 3, 4, 6, 7, 5, 2, 1, 8, 9])
>>> canonical_free(sbase, [Permutation(h) for h in sgens], g, 2)
[0, 3, 4, 6, 1, 2, 7, 5, 9, 8]
"""
g = g.array_form
size = len(g)
if not base:
return g[:]
transversals = get_transversals(base, gens)
for x in sorted(g[:-2]):
if x not in base:
base.append(x)
h = g
for i, transv in enumerate(transversals):
h_i = [size]*num_free
# find the element s in transversals[i] such that
# _af_rmul(h, s) has its free elements with the lowest position in h
s = None
for sk in transv.values():
h1 = _af_rmul(h, sk)
hi = [h1.index(ix) for ix in range(num_free)]
if hi < h_i:
h_i = hi
s = sk
if s:
h = _af_rmul(h, s)
return h
def _get_map_slots(size, fixed_slots):
res = list(range(size))
pos = 0
for i in range(size):
if i in fixed_slots:
continue
res[i] = pos
pos += 1
return res
def _lift_sgens(size, fixed_slots, free, s):
a = []
j = k = 0
fd = list(zip(fixed_slots, free))
fd = [y for x, y in sorted(fd)]
num_free = len(free)
for i in range(size):
if i in fixed_slots:
a.append(fd[k])
k += 1
else:
a.append(s[j] + num_free)
j += 1
return a
def canonicalize(g, dummies, msym, *v):
"""
canonicalize tensor formed by tensors
Parameters
==========
g : permutation representing the tensor
dummies : list representing the dummy indices
it can be a list of dummy indices of the same type
or a list of lists of dummy indices, one list for each
type of index;
the dummy indices must come after the free indices,
and put in order contravariant, covariant
[d0, -d0, d1,-d1,...]
msym : symmetry of the metric(s)
it can be an integer or a list;
in the first case it is the symmetry of the dummy index metric;
in the second case it is the list of the symmetries of the
index metric for each type
v : list, (base_i, gens_i, n_i, sym_i) for tensors of type `i`
base_i, gens_i : BSGS for tensors of this type.
The BSGS should have minimal base under lexicographic ordering;
if not, an attempt is made do get the minimal BSGS;
in case of failure,
canonicalize_naive is used, which is much slower.
n_i : number of tensors of type `i`.
sym_i : symmetry under exchange of component tensors of type `i`.
Both for msym and sym_i the cases are
* None no symmetry
* 0 commuting
* 1 anticommuting
Returns
=======
0 if the tensor is zero, else return the array form of
the permutation representing the canonical form of the tensor.
Algorithm
=========
First one uses canonical_free to get the minimum tensor under
lexicographic order, using only the slot symmetries.
If the component tensors have not minimal BSGS, it is attempted
to find it; if the attempt fails canonicalize_naive
is used instead.
Compute the residual slot symmetry keeping fixed the free indices
using tensor_gens(base, gens, list_free_indices, sym).
Reduce the problem eliminating the free indices.
Then use double_coset_can_rep and lift back the result reintroducing
the free indices.
Examples
========
one type of index with commuting metric;
`A_{a b}` and `B_{a b}` antisymmetric and commuting
`T = A_{d0 d1} * B^{d0}{}_{d2} * B^{d2 d1}`
`ord = [d0,-d0,d1,-d1,d2,-d2]` order of the indices
g = [1, 3, 0, 5, 4, 2, 6, 7]
`T_c = 0`
>>> from sympy.combinatorics.tensor_can import get_symmetric_group_sgs, canonicalize, bsgs_direct_product
>>> from sympy.combinatorics import Permutation
>>> base2a, gens2a = get_symmetric_group_sgs(2, 1)
>>> t0 = (base2a, gens2a, 1, 0)
>>> t1 = (base2a, gens2a, 2, 0)
>>> g = Permutation([1, 3, 0, 5, 4, 2, 6, 7])
>>> canonicalize(g, range(6), 0, t0, t1)
0
same as above, but with `B_{a b}` anticommuting
`T_c = -A^{d0 d1} * B_{d0}{}^{d2} * B_{d1 d2}`
can = [0,2,1,4,3,5,7,6]
>>> t1 = (base2a, gens2a, 2, 1)
>>> canonicalize(g, range(6), 0, t0, t1)
[0, 2, 1, 4, 3, 5, 7, 6]
two types of indices `[a,b,c,d,e,f]` and `[m,n]`, in this order,
both with commuting metric
`f^{a b c}` antisymmetric, commuting
`A_{m a}` no symmetry, commuting
`T = f^c{}_{d a} * f^f{}_{e b} * A_m{}^d * A^{m b} * A_n{}^a * A^{n e}`
ord = [c,f,a,-a,b,-b,d,-d,e,-e,m,-m,n,-n]
g = [0,7,3, 1,9,5, 11,6, 10,4, 13,2, 12,8, 14,15]
The canonical tensor is
`T_c = -f^{c a b} * f^{f d e} * A^m{}_a * A_{m d} * A^n{}_b * A_{n e}`
can = [0,2,4, 1,6,8, 10,3, 11,7, 12,5, 13,9, 15,14]
>>> base_f, gens_f = get_symmetric_group_sgs(3, 1)
>>> base1, gens1 = get_symmetric_group_sgs(1)
>>> base_A, gens_A = bsgs_direct_product(base1, gens1, base1, gens1)
>>> t0 = (base_f, gens_f, 2, 0)
>>> t1 = (base_A, gens_A, 4, 0)
>>> dummies = [range(2, 10), range(10, 14)]
>>> g = Permutation([0, 7, 3, 1, 9, 5, 11, 6, 10, 4, 13, 2, 12, 8, 14, 15])
>>> canonicalize(g, dummies, [0, 0], t0, t1)
[0, 2, 4, 1, 6, 8, 10, 3, 11, 7, 12, 5, 13, 9, 15, 14]
"""
from sympy.combinatorics.testutil import canonicalize_naive
if not isinstance(msym, list):
if not msym in [0, 1, None]:
raise ValueError('msym must be 0, 1 or None')
num_types = 1
else:
num_types = len(msym)
if not all(msymx in [0, 1, None] for msymx in msym):
raise ValueError('msym entries must be 0, 1 or None')
if len(dummies) != num_types:
raise ValueError(
'dummies and msym must have the same number of elements')
size = g.size
num_tensors = 0
v1 = []
for i in range(len(v)):
base_i, gens_i, n_i, sym_i = v[i]
# check that the BSGS is minimal;
# this property is used in double_coset_can_rep;
# if it is not minimal use canonicalize_naive
if not _is_minimal_bsgs(base_i, gens_i):
mbsgs = get_minimal_bsgs(base_i, gens_i)
if not mbsgs:
can = canonicalize_naive(g, dummies, msym, *v)
return can
base_i, gens_i = mbsgs
v1.append((base_i, gens_i, [[]] * n_i, sym_i))
num_tensors += n_i
if num_types == 1 and not isinstance(msym, list):
dummies = [dummies]
msym = [msym]
flat_dummies = []
for dumx in dummies:
flat_dummies.extend(dumx)
if flat_dummies and flat_dummies != list(range(flat_dummies[0], flat_dummies[-1] + 1)):
raise ValueError('dummies is not valid')
# slot symmetry of the tensor
size1, sbase, sgens = gens_products(*v1)
if size != size1:
raise ValueError(
'g has size %d, generators have size %d' % (size, size1))
free = [i for i in range(size - 2) if i not in flat_dummies]
num_free = len(free)
# g1 minimal tensor under slot symmetry
g1 = canonical_free(sbase, sgens, g, num_free)
if not flat_dummies:
return g1
# save the sign of g1
sign = 0 if g1[-1] == size - 1 else 1
# the free indices are kept fixed.
# Determine free_i, the list of slots of tensors which are fixed
# since they are occupied by free indices, which are fixed.
start = 0
for i in range(len(v)):
free_i = []
base_i, gens_i, n_i, sym_i = v[i]
len_tens = gens_i[0].size - 2
# for each component tensor get a list od fixed islots
for j in range(n_i):
# get the elements corresponding to the component tensor
h = g1[start:(start + len_tens)]
fr = []
# get the positions of the fixed elements in h
for k in free:
if k in h:
fr.append(h.index(k))
free_i.append(fr)
start += len_tens
v1[i] = (base_i, gens_i, free_i, sym_i)
# BSGS of the tensor with fixed free indices
# if tensor_gens fails in gens_product, use canonicalize_naive
size, sbase, sgens = gens_products(*v1)
# reduce the permutations getting rid of the free indices
pos_free = [g1.index(x) for x in range(num_free)]
size_red = size - num_free
g1_red = [x - num_free for x in g1 if x in flat_dummies]
if sign:
g1_red.extend([size_red - 1, size_red - 2])
else:
g1_red.extend([size_red - 2, size_red - 1])
map_slots = _get_map_slots(size, pos_free)
sbase_red = [map_slots[i] for i in sbase if i not in pos_free]
sgens_red = [_af_new([map_slots[i] for i in y._array_form if i not in pos_free]) for y in sgens]
dummies_red = [[x - num_free for x in y] for y in dummies]
transv_red = get_transversals(sbase_red, sgens_red)
g1_red = _af_new(g1_red)
g2 = double_coset_can_rep(
dummies_red, msym, sbase_red, sgens_red, transv_red, g1_red)
if g2 == 0:
return 0
# lift to the case with the free indices
g3 = _lift_sgens(size, pos_free, free, g2)
return g3
def perm_af_direct_product(gens1, gens2, signed=True):
"""
direct products of the generators gens1 and gens2
Examples
========
>>> from sympy.combinatorics.tensor_can import perm_af_direct_product
>>> gens1 = [[1, 0, 2, 3], [0, 1, 3, 2]]
>>> gens2 = [[1, 0]]
>>> perm_af_direct_product(gens1, gens2, False)
[[1, 0, 2, 3, 4, 5], [0, 1, 3, 2, 4, 5], [0, 1, 2, 3, 5, 4]]
>>> gens1 = [[1, 0, 2, 3, 5, 4], [0, 1, 3, 2, 4, 5]]
>>> gens2 = [[1, 0, 2, 3]]
>>> perm_af_direct_product(gens1, gens2, True)
[[1, 0, 2, 3, 4, 5, 7, 6], [0, 1, 3, 2, 4, 5, 6, 7], [0, 1, 2, 3, 5, 4, 6, 7]]
"""
gens1 = [list(x) for x in gens1]
gens2 = [list(x) for x in gens2]
s = 2 if signed else 0
n1 = len(gens1[0]) - s
n2 = len(gens2[0]) - s
start = list(range(n1))
end = list(range(n1, n1 + n2))
if signed:
gens1 = [gen[:-2] + end + [gen[-2] + n2, gen[-1] + n2]
for gen in gens1]
gens2 = [start + [x + n1 for x in gen] for gen in gens2]
else:
gens1 = [gen + end for gen in gens1]
gens2 = [start + [x + n1 for x in gen] for gen in gens2]
res = gens1 + gens2
return res
def bsgs_direct_product(base1, gens1, base2, gens2, signed=True):
"""
Direct product of two BSGS
Parameters
==========
base1 base of the first BSGS.
gens1 strong generating sequence of the first BSGS.
base2, gens2 similarly for the second BSGS.
signed flag for signed permutations.
Examples
========
>>> from sympy.combinatorics import Permutation
>>> from sympy.combinatorics.tensor_can import (get_symmetric_group_sgs, bsgs_direct_product)
>>> Permutation.print_cyclic = True
>>> base1, gens1 = get_symmetric_group_sgs(1)
>>> base2, gens2 = get_symmetric_group_sgs(2)
>>> bsgs_direct_product(base1, gens1, base2, gens2)
([1], [(4)(1 2)])
"""
s = 2 if signed else 0
n1 = gens1[0].size - s
base = list(base1)
base += [x + n1 for x in base2]
gens1 = [h._array_form for h in gens1]
gens2 = [h._array_form for h in gens2]
gens = perm_af_direct_product(gens1, gens2, signed)
size = len(gens[0])
id_af = list(range(size))
gens = [h for h in gens if h != id_af]
if not gens:
gens = [id_af]
return base, [_af_new(h) for h in gens]
def get_symmetric_group_sgs(n, antisym=False):
"""
Return base, gens of the minimal BSGS for (anti)symmetric tensor
``n`` rank of the tensor
``antisym = False`` symmetric tensor
``antisym = True`` antisymmetric tensor
Examples
========
>>> from sympy.combinatorics import Permutation
>>> from sympy.combinatorics.tensor_can import get_symmetric_group_sgs
>>> Permutation.print_cyclic = True
>>> get_symmetric_group_sgs(3)
([0, 1], [(4)(0 1), (4)(1 2)])
"""
if n == 1:
return [], [_af_new(list(range(3)))]
gens = [Permutation(n - 1)(i, i + 1)._array_form for i in range(n - 1)]
if antisym == 0:
gens = [x + [n, n + 1] for x in gens]
else:
gens = [x + [n + 1, n] for x in gens]
base = list(range(n - 1))
return base, [_af_new(h) for h in gens]
riemann_bsgs = [0, 2], [Permutation(0, 1)(4, 5), Permutation(2, 3)(4, 5),
Permutation(5)(0, 2)(1, 3)]
def get_transversals(base, gens):
"""
Return transversals for the group with BSGS base, gens
"""
if not base:
return []
stabs = _distribute_gens_by_base(base, gens)
orbits, transversals = _orbits_transversals_from_bsgs(base, stabs)
transversals = [{x: h._array_form for x, h in y.items()} for y in
transversals]
return transversals
def _is_minimal_bsgs(base, gens):
"""
Check if the BSGS has minimal base under lexigographic order.
base, gens BSGS
Examples
========
>>> from sympy.combinatorics import Permutation
>>> from sympy.combinatorics.tensor_can import riemann_bsgs, _is_minimal_bsgs
>>> _is_minimal_bsgs(*riemann_bsgs)
True
>>> riemann_bsgs1 = ([2, 0], ([Permutation(5)(0, 1)(4, 5), Permutation(5)(0, 2)(1, 3)]))
>>> _is_minimal_bsgs(*riemann_bsgs1)
False
"""
base1 = []
sgs1 = gens[:]
size = gens[0].size
for i in range(size):
if not all(h._array_form[i] == i for h in sgs1):
base1.append(i)
sgs1 = [h for h in sgs1 if h._array_form[i] == i]
return base1 == base
def get_minimal_bsgs(base, gens):
"""
Compute a minimal GSGS
base, gens BSGS
If base, gens is a minimal BSGS return it; else return a minimal BSGS
if it fails in finding one, it returns None
TODO: use baseswap in the case in which if it fails in finding a
minimal BSGS
Examples
========
>>> from sympy.combinatorics import Permutation
>>> from sympy.combinatorics.tensor_can import get_minimal_bsgs
>>> Permutation.print_cyclic = True
>>> riemann_bsgs1 = ([2, 0], ([Permutation(5)(0, 1)(4, 5), Permutation(5)(0, 2)(1, 3)]))
>>> get_minimal_bsgs(*riemann_bsgs1)
([0, 2], [(0 1)(4 5), (5)(0 2)(1 3), (2 3)(4 5)])
"""
G = PermutationGroup(gens)
base, gens = G.schreier_sims_incremental()
if not _is_minimal_bsgs(base, gens):
return None
return base, gens
def tensor_gens(base, gens, list_free_indices, sym=0):
"""
Returns size, res_base, res_gens BSGS for n tensors of the
same type
base, gens BSGS for tensors of this type
list_free_indices list of the slots occupied by fixed indices
for each of the tensors
sym symmetry under commutation of two tensors
sym None no symmetry
sym 0 commuting
sym 1 anticommuting
Examples
========
>>> from sympy.combinatorics import Permutation
>>> from sympy.combinatorics.tensor_can import tensor_gens, get_symmetric_group_sgs
>>> Permutation.print_cyclic = True
two symmetric tensors with 3 indices without free indices
>>> base, gens = get_symmetric_group_sgs(3)
>>> tensor_gens(base, gens, [[], []])
(8, [0, 1, 3, 4], [(7)(0 1), (7)(1 2), (7)(3 4), (7)(4 5), (7)(0 3)(1 4)(2 5)])
two symmetric tensors with 3 indices with free indices in slot 1 and 0
>>> tensor_gens(base, gens, [[1], [0]])
(8, [0, 4], [(7)(0 2), (7)(4 5)])
four symmetric tensors with 3 indices, two of which with free indices
"""
def _get_bsgs(G, base, gens, free_indices):
"""
return the BSGS for G.pointwise_stabilizer(free_indices)
"""
if not free_indices:
return base[:], gens[:]
else:
H = G.pointwise_stabilizer(free_indices)
base, sgs = H.schreier_sims_incremental()
return base, sgs
# if not base there is no slot symmetry for the component tensors
# if list_free_indices.count([]) < 2 there is no commutation symmetry
# so there is no resulting slot symmetry
if not base and list_free_indices.count([]) < 2:
n = len(list_free_indices)
size = gens[0].size
size = n * (gens[0].size - 2) + 2
return size, [], [_af_new(list(range(size)))]
# if any(list_free_indices) one needs to compute the pointwise
# stabilizer, so G is needed
if any(list_free_indices):
G = PermutationGroup(gens)
else:
G = None
# no_free list of lists of indices for component tensors without fixed
# indices
no_free = []
size = gens[0].size
id_af = list(range(size))
num_indices = size - 2
if not list_free_indices[0]:
no_free.append(list(range(num_indices)))
res_base, res_gens = _get_bsgs(G, base, gens, list_free_indices[0])
for i in range(1, len(list_free_indices)):
base1, gens1 = _get_bsgs(G, base, gens, list_free_indices[i])
res_base, res_gens = bsgs_direct_product(res_base, res_gens,
base1, gens1, 1)
if not list_free_indices[i]:
no_free.append(list(range(size - 2, size - 2 + num_indices)))
size += num_indices
nr = size - 2
res_gens = [h for h in res_gens if h._array_form != id_af]
# if sym there are no commuting tensors stop here
if sym is None or not no_free:
if not res_gens:
res_gens = [_af_new(id_af)]
return size, res_base, res_gens
# if the component tensors have moinimal BSGS, so is their direct
# product P; the slot symmetry group is S = P*C, where C is the group
# to (anti)commute the component tensors with no free indices
# a stabilizer has the property S_i = P_i*C_i;
# the BSGS of P*C has SGS_P + SGS_C and the base is
# the ordered union of the bases of P and C.
# If P has minimal BSGS, so has S with this base.
base_comm = []
for i in range(len(no_free) - 1):
ind1 = no_free[i]
ind2 = no_free[i + 1]
a = list(range(ind1[0]))
a.extend(ind2)
a.extend(ind1)
base_comm.append(ind1[0])
a.extend(list(range(ind2[-1] + 1, nr)))
if sym == 0:
a.extend([nr, nr + 1])
else:
a.extend([nr + 1, nr])
res_gens.append(_af_new(a))
res_base = list(res_base)
# each base is ordered; order the union of the two bases
for i in base_comm:
if i not in res_base:
res_base.append(i)
res_base.sort()
if not res_gens:
res_gens = [_af_new(id_af)]
return size, res_base, res_gens
def gens_products(*v):
"""
Returns size, res_base, res_gens BSGS for n tensors of different types
v is a sequence of (base_i, gens_i, free_i, sym_i)
where
base_i, gens_i BSGS of tensor of type `i`
free_i list of the fixed slots for each of the tensors
of type `i`; if there are `n_i` tensors of type `i`
and none of them have fixed slots, `free = [[]]*n_i`
sym 0 (1) if the tensors of type `i` (anti)commute among themselves
Examples
========
>>> from sympy.combinatorics import Permutation
>>> from sympy.combinatorics.tensor_can import get_symmetric_group_sgs, gens_products
>>> Permutation.print_cyclic = True
>>> base, gens = get_symmetric_group_sgs(2)
>>> gens_products((base, gens, [[], []], 0))
(6, [0, 2], [(5)(0 1), (5)(2 3), (5)(0 2)(1 3)])
>>> gens_products((base, gens, [[1], []], 0))
(6, [2], [(5)(2 3)])
"""
res_size, res_base, res_gens = tensor_gens(*v[0])
for i in range(1, len(v)):
size, base, gens = tensor_gens(*v[i])
res_base, res_gens = bsgs_direct_product(res_base, res_gens, base,
gens, 1)
res_size = res_gens[0].size
id_af = list(range(res_size))
res_gens = [h for h in res_gens if h != id_af]
if not res_gens:
res_gens = [id_af]
return res_size, res_base, res_gens
|
31cba8bb775ca3b047717604e3409e0c258e98dfa74bb113345d28e3be7b0b27
|
from __future__ import print_function, division
from sympy.combinatorics import Permutation as Perm
from sympy.combinatorics.perm_groups import PermutationGroup
from sympy.core import Basic, Tuple
from sympy.core.compatibility import as_int, range
from sympy.sets import FiniteSet
from sympy.utilities.iterables import (minlex, unflatten, flatten)
rmul = Perm.rmul
class Polyhedron(Basic):
"""
Represents the polyhedral symmetry group (PSG).
The PSG is one of the symmetry groups of the Platonic solids.
There are three polyhedral groups: the tetrahedral group
of order 12, the octahedral group of order 24, and the
icosahedral group of order 60.
All doctests have been given in the docstring of the
constructor of the object.
References
==========
http://mathworld.wolfram.com/PolyhedralGroup.html
"""
_edges = None
def __new__(cls, corners, faces=[], pgroup=[]):
"""
The constructor of the Polyhedron group object.
It takes up to three parameters: the corners, faces, and
allowed transformations.
The corners/vertices are entered as a list of arbitrary
expressions that are used to identify each vertex.
The faces are entered as a list of tuples of indices; a tuple
of indices identifies the vertices which define the face. They
should be entered in a cw or ccw order; they will be standardized
by reversal and rotation to be give the lowest lexical ordering.
If no faces are given then no edges will be computed.
>>> from sympy.combinatorics.polyhedron import Polyhedron
>>> Polyhedron(list('abc'), [(1, 2, 0)]).faces
{(0, 1, 2)}
>>> Polyhedron(list('abc'), [(1, 0, 2)]).faces
{(0, 1, 2)}
The allowed transformations are entered as allowable permutations
of the vertices for the polyhedron. Instance of Permutations
(as with faces) should refer to the supplied vertices by index.
These permutation are stored as a PermutationGroup.
Examples
========
>>> from sympy.combinatorics.permutations import Permutation
>>> Permutation.print_cyclic = False
>>> from sympy.abc import w, x, y, z
Here we construct the Polyhedron object for a tetrahedron.
>>> corners = [w, x, y, z]
>>> faces = [(0, 1, 2), (0, 2, 3), (0, 3, 1), (1, 2, 3)]
Next, allowed transformations of the polyhedron must be given. This
is given as permutations of vertices.
Although the vertices of a tetrahedron can be numbered in 24 (4!)
different ways, there are only 12 different orientations for a
physical tetrahedron. The following permutations, applied once or
twice, will generate all 12 of the orientations. (The identity
permutation, Permutation(range(4)), is not included since it does
not change the orientation of the vertices.)
>>> pgroup = [Permutation([[0, 1, 2], [3]]), \
Permutation([[0, 1, 3], [2]]), \
Permutation([[0, 2, 3], [1]]), \
Permutation([[1, 2, 3], [0]]), \
Permutation([[0, 1], [2, 3]]), \
Permutation([[0, 2], [1, 3]]), \
Permutation([[0, 3], [1, 2]])]
The Polyhedron is now constructed and demonstrated:
>>> tetra = Polyhedron(corners, faces, pgroup)
>>> tetra.size
4
>>> tetra.edges
{(0, 1), (0, 2), (0, 3), (1, 2), (1, 3), (2, 3)}
>>> tetra.corners
(w, x, y, z)
It can be rotated with an arbitrary permutation of vertices, e.g.
the following permutation is not in the pgroup:
>>> tetra.rotate(Permutation([0, 1, 3, 2]))
>>> tetra.corners
(w, x, z, y)
An allowed permutation of the vertices can be constructed by
repeatedly applying permutations from the pgroup to the vertices.
Here is a demonstration that applying p and p**2 for every p in
pgroup generates all the orientations of a tetrahedron and no others:
>>> all = ( (w, x, y, z), \
(x, y, w, z), \
(y, w, x, z), \
(w, z, x, y), \
(z, w, y, x), \
(w, y, z, x), \
(y, z, w, x), \
(x, z, y, w), \
(z, y, x, w), \
(y, x, z, w), \
(x, w, z, y), \
(z, x, w, y) )
>>> got = []
>>> for p in (pgroup + [p**2 for p in pgroup]):
... h = Polyhedron(corners)
... h.rotate(p)
... got.append(h.corners)
...
>>> set(got) == set(all)
True
The make_perm method of a PermutationGroup will randomly pick
permutations, multiply them together, and return the permutation that
can be applied to the polyhedron to give the orientation produced
by those individual permutations.
Here, 3 permutations are used:
>>> tetra.pgroup.make_perm(3) # doctest: +SKIP
Permutation([0, 3, 1, 2])
To select the permutations that should be used, supply a list
of indices to the permutations in pgroup in the order they should
be applied:
>>> use = [0, 0, 2]
>>> p002 = tetra.pgroup.make_perm(3, use)
>>> p002
Permutation([1, 0, 3, 2])
Apply them one at a time:
>>> tetra.reset()
>>> for i in use:
... tetra.rotate(pgroup[i])
...
>>> tetra.vertices
(x, w, z, y)
>>> sequentially = tetra.vertices
Apply the composite permutation:
>>> tetra.reset()
>>> tetra.rotate(p002)
>>> tetra.corners
(x, w, z, y)
>>> tetra.corners in all and tetra.corners == sequentially
True
Notes
=====
Defining permutation groups
---------------------------
It is not necessary to enter any permutations, nor is necessary to
enter a complete set of transformations. In fact, for a polyhedron,
all configurations can be constructed from just two permutations.
For example, the orientations of a tetrahedron can be generated from
an axis passing through a vertex and face and another axis passing
through a different vertex or from an axis passing through the
midpoints of two edges opposite of each other.
For simplicity of presentation, consider a square --
not a cube -- with vertices 1, 2, 3, and 4:
1-----2 We could think of axes of rotation being:
| | 1) through the face
| | 2) from midpoint 1-2 to 3-4 or 1-3 to 2-4
3-----4 3) lines 1-4 or 2-3
To determine how to write the permutations, imagine 4 cameras,
one at each corner, labeled A-D:
A B A B
1-----2 1-----3 vertex index:
| | | | 1 0
| | | | 2 1
3-----4 2-----4 3 2
C D C D 4 3
original after rotation
along 1-4
A diagonal and a face axis will be chosen for the "permutation group"
from which any orientation can be constructed.
>>> pgroup = []
Imagine a clockwise rotation when viewing 1-4 from camera A. The new
orientation is (in camera-order): 1, 3, 2, 4 so the permutation is
given using the *indices* of the vertices as:
>>> pgroup.append(Permutation((0, 2, 1, 3)))
Now imagine rotating clockwise when looking down an axis entering the
center of the square as viewed. The new camera-order would be
3, 1, 4, 2 so the permutation is (using indices):
>>> pgroup.append(Permutation((2, 0, 3, 1)))
The square can now be constructed:
** use real-world labels for the vertices, entering them in
camera order
** for the faces we use zero-based indices of the vertices
in *edge-order* as the face is traversed; neither the
direction nor the starting point matter -- the faces are
only used to define edges (if so desired).
>>> square = Polyhedron((1, 2, 3, 4), [(0, 1, 3, 2)], pgroup)
To rotate the square with a single permutation we can do:
>>> square.rotate(square.pgroup[0])
>>> square.corners
(1, 3, 2, 4)
To use more than one permutation (or to use one permutation more
than once) it is more convenient to use the make_perm method:
>>> p011 = square.pgroup.make_perm([0, 1, 1]) # diag flip + 2 rotations
>>> square.reset() # return to initial orientation
>>> square.rotate(p011)
>>> square.corners
(4, 2, 3, 1)
Thinking outside the box
------------------------
Although the Polyhedron object has a direct physical meaning, it
actually has broader application. In the most general sense it is
just a decorated PermutationGroup, allowing one to connect the
permutations to something physical. For example, a Rubik's cube is
not a proper polyhedron, but the Polyhedron class can be used to
represent it in a way that helps to visualize the Rubik's cube.
>>> from sympy.utilities.iterables import flatten, unflatten
>>> from sympy import symbols
>>> from sympy.combinatorics import RubikGroup
>>> facelets = flatten([symbols(s+'1:5') for s in 'UFRBLD'])
>>> def show():
... pairs = unflatten(r2.corners, 2)
... print(pairs[::2])
... print(pairs[1::2])
...
>>> r2 = Polyhedron(facelets, pgroup=RubikGroup(2))
>>> show()
[(U1, U2), (F1, F2), (R1, R2), (B1, B2), (L1, L2), (D1, D2)]
[(U3, U4), (F3, F4), (R3, R4), (B3, B4), (L3, L4), (D3, D4)]
>>> r2.rotate(0) # cw rotation of F
>>> show()
[(U1, U2), (F3, F1), (U3, R2), (B1, B2), (L1, D1), (R3, R1)]
[(L4, L2), (F4, F2), (U4, R4), (B3, B4), (L3, D2), (D3, D4)]
Predefined Polyhedra
====================
For convenience, the vertices and faces are defined for the following
standard solids along with a permutation group for transformations.
When the polyhedron is oriented as indicated below, the vertices in
a given horizontal plane are numbered in ccw direction, starting from
the vertex that will give the lowest indices in a given face. (In the
net of the vertices, indices preceded by "-" indicate replication of
the lhs index in the net.)
tetrahedron, tetrahedron_faces
------------------------------
4 vertices (vertex up) net:
0 0-0
1 2 3-1
4 faces:
(0, 1, 2) (0, 2, 3) (0, 3, 1) (1, 2, 3)
cube, cube_faces
----------------
8 vertices (face up) net:
0 1 2 3-0
4 5 6 7-4
6 faces:
(0, 1, 2, 3)
(0, 1, 5, 4) (1, 2, 6, 5) (2, 3, 7, 6) (0, 3, 7, 4)
(4, 5, 6, 7)
octahedron, octahedron_faces
----------------------------
6 vertices (vertex up) net:
0 0 0-0
1 2 3 4-1
5 5 5-5
8 faces:
(0, 1, 2) (0, 2, 3) (0, 3, 4) (0, 1, 4)
(1, 2, 5) (2, 3, 5) (3, 4, 5) (1, 4, 5)
dodecahedron, dodecahedron_faces
--------------------------------
20 vertices (vertex up) net:
0 1 2 3 4 -0
5 6 7 8 9 -5
14 10 11 12 13-14
15 16 17 18 19-15
12 faces:
(0, 1, 2, 3, 4) (0, 1, 6, 10, 5) (1, 2, 7, 11, 6)
(2, 3, 8, 12, 7) (3, 4, 9, 13, 8) (0, 4, 9, 14, 5)
(5, 10, 16, 15, 14) (6, 10, 16, 17, 11) (7, 11, 17, 18, 12)
(8, 12, 18, 19, 13) (9, 13, 19, 15, 14)(15, 16, 17, 18, 19)
icosahedron, icosahedron_faces
------------------------------
12 vertices (face up) net:
0 0 0 0 -0
1 2 3 4 5 -1
6 7 8 9 10 -6
11 11 11 11 -11
20 faces:
(0, 1, 2) (0, 2, 3) (0, 3, 4)
(0, 4, 5) (0, 1, 5) (1, 2, 6)
(2, 3, 7) (3, 4, 8) (4, 5, 9)
(1, 5, 10) (2, 6, 7) (3, 7, 8)
(4, 8, 9) (5, 9, 10) (1, 6, 10)
(6, 7, 11) (7, 8, 11) (8, 9, 11)
(9, 10, 11) (6, 10, 11)
>>> from sympy.combinatorics.polyhedron import cube
>>> cube.edges
{(0, 1), (0, 3), (0, 4), '...', (4, 7), (5, 6), (6, 7)}
If you want to use letters or other names for the corners you
can still use the pre-calculated faces:
>>> corners = list('abcdefgh')
>>> Polyhedron(corners, cube.faces).corners
(a, b, c, d, e, f, g, h)
References
==========
.. [1] www.ocf.berkeley.edu/~wwu/articles/platonicsolids.pdf
"""
faces = [minlex(f, directed=False, is_set=True) for f in faces]
corners, faces, pgroup = args = \
[Tuple(*a) for a in (corners, faces, pgroup)]
obj = Basic.__new__(cls, *args)
obj._corners = tuple(corners) # in order given
obj._faces = FiniteSet(*faces)
if pgroup and pgroup[0].size != len(corners):
raise ValueError("Permutation size unequal to number of corners.")
# use the identity permutation if none are given
obj._pgroup = PermutationGroup((
pgroup or [Perm(range(len(corners)))] ))
return obj
@property
def corners(self):
"""
Get the corners of the Polyhedron.
The method ``vertices`` is an alias for ``corners``.
Examples
========
>>> from sympy.combinatorics import Polyhedron
>>> from sympy.abc import a, b, c, d
>>> p = Polyhedron(list('abcd'))
>>> p.corners == p.vertices == (a, b, c, d)
True
See Also
========
array_form, cyclic_form
"""
return self._corners
vertices = corners
@property
def array_form(self):
"""Return the indices of the corners.
The indices are given relative to the original position of corners.
Examples
========
>>> from sympy.combinatorics import Permutation, Cycle
>>> from sympy.combinatorics.polyhedron import tetrahedron
>>> tetrahedron = tetrahedron.copy()
>>> tetrahedron.array_form
[0, 1, 2, 3]
>>> tetrahedron.rotate(0)
>>> tetrahedron.array_form
[0, 2, 3, 1]
>>> tetrahedron.pgroup[0].array_form
[0, 2, 3, 1]
See Also
========
corners, cyclic_form
"""
corners = list(self.args[0])
return [corners.index(c) for c in self.corners]
@property
def cyclic_form(self):
"""Return the indices of the corners in cyclic notation.
The indices are given relative to the original position of corners.
See Also
========
corners, array_form
"""
return Perm._af_new(self.array_form).cyclic_form
@property
def size(self):
"""
Get the number of corners of the Polyhedron.
"""
return len(self._corners)
@property
def faces(self):
"""
Get the faces of the Polyhedron.
"""
return self._faces
@property
def pgroup(self):
"""
Get the permutations of the Polyhedron.
"""
return self._pgroup
@property
def edges(self):
"""
Given the faces of the polyhedra we can get the edges.
Examples
========
>>> from sympy.combinatorics import Polyhedron
>>> from sympy.abc import a, b, c
>>> corners = (a, b, c)
>>> faces = [(0, 1, 2)]
>>> Polyhedron(corners, faces).edges
{(0, 1), (0, 2), (1, 2)}
"""
if self._edges is None:
output = set()
for face in self.faces:
for i in range(len(face)):
edge = tuple(sorted([face[i], face[i - 1]]))
output.add(edge)
self._edges = FiniteSet(*output)
return self._edges
def rotate(self, perm):
"""
Apply a permutation to the polyhedron *in place*. The permutation
may be given as a Permutation instance or an integer indicating
which permutation from pgroup of the Polyhedron should be
applied.
This is an operation that is analogous to rotation about
an axis by a fixed increment.
Notes
=====
When a Permutation is applied, no check is done to see if that
is a valid permutation for the Polyhedron. For example, a cube
could be given a permutation which effectively swaps only 2
vertices. A valid permutation (that rotates the object in a
physical way) will be obtained if one only uses
permutations from the ``pgroup`` of the Polyhedron. On the other
hand, allowing arbitrary rotations (applications of permutations)
gives a way to follow named elements rather than indices since
Polyhedron allows vertices to be named while Permutation works
only with indices.
Examples
========
>>> from sympy.combinatorics import Polyhedron, Permutation
>>> from sympy.combinatorics.polyhedron import cube
>>> cube = cube.copy()
>>> cube.corners
(0, 1, 2, 3, 4, 5, 6, 7)
>>> cube.rotate(0)
>>> cube.corners
(1, 2, 3, 0, 5, 6, 7, 4)
A non-physical "rotation" that is not prohibited by this method:
>>> cube.reset()
>>> cube.rotate(Permutation([[1, 2]], size=8))
>>> cube.corners
(0, 2, 1, 3, 4, 5, 6, 7)
Polyhedron can be used to follow elements of set that are
identified by letters instead of integers:
>>> shadow = h5 = Polyhedron(list('abcde'))
>>> p = Permutation([3, 0, 1, 2, 4])
>>> h5.rotate(p)
>>> h5.corners
(d, a, b, c, e)
>>> _ == shadow.corners
True
>>> copy = h5.copy()
>>> h5.rotate(p)
>>> h5.corners == copy.corners
False
"""
if not isinstance(perm, Perm):
perm = self.pgroup[perm]
# and we know it's valid
else:
if perm.size != self.size:
raise ValueError('Polyhedron and Permutation sizes differ.')
a = perm.array_form
corners = [self.corners[a[i]] for i in range(len(self.corners))]
self._corners = tuple(corners)
def reset(self):
"""Return corners to their original positions.
Examples
========
>>> from sympy.combinatorics.polyhedron import tetrahedron as T
>>> T = T.copy()
>>> T.corners
(0, 1, 2, 3)
>>> T.rotate(0)
>>> T.corners
(0, 2, 3, 1)
>>> T.reset()
>>> T.corners
(0, 1, 2, 3)
"""
self._corners = self.args[0]
def _pgroup_calcs():
"""Return the permutation groups for each of the polyhedra and the face
definitions: tetrahedron, cube, octahedron, dodecahedron, icosahedron,
tetrahedron_faces, cube_faces, octahedron_faces, dodecahedron_faces,
icosahedron_faces
(This author didn't find and didn't know of a better way to do it though
there likely is such a way.)
Although only 2 permutations are needed for a polyhedron in order to
generate all the possible orientations, a group of permutations is
provided instead. A set of permutations is called a "group" if::
a*b = c (for any pair of permutations in the group, a and b, their
product, c, is in the group)
a*(b*c) = (a*b)*c (for any 3 permutations in the group associativity holds)
there is an identity permutation, I, such that I*a = a*I for all elements
in the group
a*b = I (the inverse of each permutation is also in the group)
None of the polyhedron groups defined follow these definitions of a group.
Instead, they are selected to contain those permutations whose powers
alone will construct all orientations of the polyhedron, i.e. for
permutations ``a``, ``b``, etc... in the group, ``a, a**2, ..., a**o_a``,
``b, b**2, ..., b**o_b``, etc... (where ``o_i`` is the order of
permutation ``i``) generate all permutations of the polyhedron instead of
mixed products like ``a*b``, ``a*b**2``, etc....
Note that for a polyhedron with n vertices, the valid permutations of the
vertices exclude those that do not maintain its faces. e.g. the
permutation BCDE of a square's four corners, ABCD, is a valid
permutation while CBDE is not (because this would twist the square).
Examples
========
The is_group checks for: closure, the presence of the Identity permutation,
and the presence of the inverse for each of the elements in the group. This
confirms that none of the polyhedra are true groups:
>>> from sympy.combinatorics.polyhedron import (
... tetrahedron, cube, octahedron, dodecahedron, icosahedron)
...
>>> polyhedra = (tetrahedron, cube, octahedron, dodecahedron, icosahedron)
>>> [h.pgroup.is_group for h in polyhedra]
...
[True, True, True, True, True]
Although tests in polyhedron's test suite check that powers of the
permutations in the groups generate all permutations of the vertices
of the polyhedron, here we also demonstrate the powers of the given
permutations create a complete group for the tetrahedron:
>>> from sympy.combinatorics import Permutation, PermutationGroup
>>> for h in polyhedra[:1]:
... G = h.pgroup
... perms = set()
... for g in G:
... for e in range(g.order()):
... p = tuple((g**e).array_form)
... perms.add(p)
...
... perms = [Permutation(p) for p in perms]
... assert PermutationGroup(perms).is_group
In addition to doing the above, the tests in the suite confirm that the
faces are all present after the application of each permutation.
References
==========
http://dogschool.tripod.com/trianglegroup.html
"""
def _pgroup_of_double(polyh, ordered_faces, pgroup):
n = len(ordered_faces[0])
# the vertices of the double which sits inside a give polyhedron
# can be found by tracking the faces of the outer polyhedron.
# A map between face and the vertex of the double is made so that
# after rotation the position of the vertices can be located
fmap = dict(zip(ordered_faces,
range(len(ordered_faces))))
flat_faces = flatten(ordered_faces)
new_pgroup = []
for i, p in enumerate(pgroup):
h = polyh.copy()
h.rotate(p)
c = h.corners
# reorder corners in the order they should appear when
# enumerating the faces
reorder = unflatten([c[j] for j in flat_faces], n)
# make them canonical
reorder = [tuple(map(as_int,
minlex(f, directed=False, is_set=True)))
for f in reorder]
# map face to vertex: the resulting list of vertices are the
# permutation that we seek for the double
new_pgroup.append(Perm([fmap[f] for f in reorder]))
return new_pgroup
tetrahedron_faces = [
(0, 1, 2), (0, 2, 3), (0, 3, 1), # upper 3
(1, 2, 3), # bottom
]
# cw from top
#
_t_pgroup = [
Perm([[1, 2, 3], [0]]), # cw from top
Perm([[0, 1, 2], [3]]), # cw from front face
Perm([[0, 3, 2], [1]]), # cw from back right face
Perm([[0, 3, 1], [2]]), # cw from back left face
Perm([[0, 1], [2, 3]]), # through front left edge
Perm([[0, 2], [1, 3]]), # through front right edge
Perm([[0, 3], [1, 2]]), # through back edge
]
tetrahedron = Polyhedron(
range(4),
tetrahedron_faces,
_t_pgroup)
cube_faces = [
(0, 1, 2, 3), # upper
(0, 1, 5, 4), (1, 2, 6, 5), (2, 3, 7, 6), (0, 3, 7, 4), # middle 4
(4, 5, 6, 7), # lower
]
# U, D, F, B, L, R = up, down, front, back, left, right
_c_pgroup = [Perm(p) for p in
[
[1, 2, 3, 0, 5, 6, 7, 4], # cw from top, U
[4, 0, 3, 7, 5, 1, 2, 6], # cw from F face
[4, 5, 1, 0, 7, 6, 2, 3], # cw from R face
[1, 0, 4, 5, 2, 3, 7, 6], # cw through UF edge
[6, 2, 1, 5, 7, 3, 0, 4], # cw through UR edge
[6, 7, 3, 2, 5, 4, 0, 1], # cw through UB edge
[3, 7, 4, 0, 2, 6, 5, 1], # cw through UL edge
[4, 7, 6, 5, 0, 3, 2, 1], # cw through FL edge
[6, 5, 4, 7, 2, 1, 0, 3], # cw through FR edge
[0, 3, 7, 4, 1, 2, 6, 5], # cw through UFL vertex
[5, 1, 0, 4, 6, 2, 3, 7], # cw through UFR vertex
[5, 6, 2, 1, 4, 7, 3, 0], # cw through UBR vertex
[7, 4, 0, 3, 6, 5, 1, 2], # cw through UBL
]]
cube = Polyhedron(
range(8),
cube_faces,
_c_pgroup)
octahedron_faces = [
(0, 1, 2), (0, 2, 3), (0, 3, 4), (0, 1, 4), # top 4
(1, 2, 5), (2, 3, 5), (3, 4, 5), (1, 4, 5), # bottom 4
]
octahedron = Polyhedron(
range(6),
octahedron_faces,
_pgroup_of_double(cube, cube_faces, _c_pgroup))
dodecahedron_faces = [
(0, 1, 2, 3, 4), # top
(0, 1, 6, 10, 5), (1, 2, 7, 11, 6), (2, 3, 8, 12, 7), # upper 5
(3, 4, 9, 13, 8), (0, 4, 9, 14, 5),
(5, 10, 16, 15, 14), (6, 10, 16, 17, 11), (7, 11, 17, 18,
12), # lower 5
(8, 12, 18, 19, 13), (9, 13, 19, 15, 14),
(15, 16, 17, 18, 19) # bottom
]
def _string_to_perm(s):
rv = [Perm(range(20))]
p = None
for si in s:
if si not in '01':
count = int(si) - 1
else:
count = 1
if si == '0':
p = _f0
elif si == '1':
p = _f1
rv.extend([p]*count)
return Perm.rmul(*rv)
# top face cw
_f0 = Perm([
1, 2, 3, 4, 0, 6, 7, 8, 9, 5, 11,
12, 13, 14, 10, 16, 17, 18, 19, 15])
# front face cw
_f1 = Perm([
5, 0, 4, 9, 14, 10, 1, 3, 13, 15,
6, 2, 8, 19, 16, 17, 11, 7, 12, 18])
# the strings below, like 0104 are shorthand for F0*F1*F0**4 and are
# the remaining 4 face rotations, 15 edge permutations, and the
# 10 vertex rotations.
_dodeca_pgroup = [_f0, _f1] + [_string_to_perm(s) for s in '''
0104 140 014 0410
010 1403 03104 04103 102
120 1304 01303 021302 03130
0412041 041204103 04120410 041204104 041204102
10 01 1402 0140 04102 0412 1204 1302 0130 03120'''.strip().split()]
dodecahedron = Polyhedron(
range(20),
dodecahedron_faces,
_dodeca_pgroup)
icosahedron_faces = [
[0, 1, 2], [0, 2, 3], [0, 3, 4], [0, 4, 5], [0, 1, 5],
[1, 6, 7], [1, 2, 7], [2, 7, 8], [2, 3, 8], [3, 8, 9],
[3, 4, 9], [4, 9, 10 ], [4, 5, 10], [5, 6, 10], [1, 5, 6],
[6, 7, 11], [7, 8, 11], [8, 9, 11], [9, 10, 11], [6, 10, 11]]
icosahedron = Polyhedron(
range(12),
icosahedron_faces,
_pgroup_of_double(
dodecahedron, dodecahedron_faces, _dodeca_pgroup))
return (tetrahedron, cube, octahedron, dodecahedron, icosahedron,
tetrahedron_faces, cube_faces, octahedron_faces,
dodecahedron_faces, icosahedron_faces)
(tetrahedron, cube, octahedron, dodecahedron, icosahedron,
tetrahedron_faces, cube_faces, octahedron_faces,
dodecahedron_faces, icosahedron_faces) = _pgroup_calcs()
|
1f0dfa467e4a9e40cad074cc6300603dbb00230a33770b0ccdf99793a31e85d7
|
from __future__ import print_function, division
import itertools
from sympy.combinatorics.fp_groups import FpGroup, FpSubgroup, simplify_presentation
from sympy.combinatorics.free_groups import FreeGroup
from sympy.combinatorics.perm_groups import PermutationGroup
from sympy.core.numbers import igcd
from sympy.ntheory.factor_ import totient
from sympy import S
class GroupHomomorphism(object):
'''
A class representing group homomorphisms. Instantiate using `homomorphism()`.
References
==========
.. [1] Holt, D., Eick, B. and O'Brien, E. (2005). Handbook of computational group theory.
'''
def __init__(self, domain, codomain, images):
self.domain = domain
self.codomain = codomain
self.images = images
self._inverses = None
self._kernel = None
self._image = None
def _invs(self):
'''
Return a dictionary with `{gen: inverse}` where `gen` is a rewriting
generator of `codomain` (e.g. strong generator for permutation groups)
and `inverse` is an element of its preimage
'''
image = self.image()
inverses = {}
for k in list(self.images.keys()):
v = self.images[k]
if not (v in inverses
or v.is_identity):
inverses[v] = k
if isinstance(self.codomain, PermutationGroup):
gens = image.strong_gens
else:
gens = image.generators
for g in gens:
if g in inverses or g.is_identity:
continue
w = self.domain.identity
if isinstance(self.codomain, PermutationGroup):
parts = image._strong_gens_slp[g][::-1]
else:
parts = g
for s in parts:
if s in inverses:
w = w*inverses[s]
else:
w = w*inverses[s**-1]**-1
inverses[g] = w
return inverses
def invert(self, g):
'''
Return an element of the preimage of `g` or of each element
of `g` if `g` is a list.
NOTE: If the codomain is an FpGroup, the inverse for equal
elements might not always be the same unless the FpGroup's
rewriting system is confluent. However, making a system
confluent can be time-consuming. If it's important, try
`self.codomain.make_confluent()` first.
'''
from sympy.combinatorics import Permutation
from sympy.combinatorics.free_groups import FreeGroupElement
if isinstance(g, (Permutation, FreeGroupElement)):
if isinstance(self.codomain, FpGroup):
g = self.codomain.reduce(g)
if self._inverses is None:
self._inverses = self._invs()
image = self.image()
w = self.domain.identity
if isinstance(self.codomain, PermutationGroup):
gens = image.generator_product(g)[::-1]
else:
gens = g
# the following can't be "for s in gens:"
# because that would be equivalent to
# "for s in gens.array_form:" when g is
# a FreeGroupElement. On the other hand,
# when you call gens by index, the generator
# (or inverse) at position i is returned.
for i in range(len(gens)):
s = gens[i]
if s.is_identity:
continue
if s in self._inverses:
w = w*self._inverses[s]
else:
w = w*self._inverses[s**-1]**-1
return w
elif isinstance(g, list):
return [self.invert(e) for e in g]
def kernel(self):
'''
Compute the kernel of `self`.
'''
if self._kernel is None:
self._kernel = self._compute_kernel()
return self._kernel
def _compute_kernel(self):
from sympy import S
G = self.domain
G_order = G.order()
if G_order == S.Infinity:
raise NotImplementedError(
"Kernel computation is not implemented for infinite groups")
gens = []
if isinstance(G, PermutationGroup):
K = PermutationGroup(G.identity)
else:
K = FpSubgroup(G, gens, normal=True)
i = self.image().order()
while K.order()*i != G_order:
r = G.random()
k = r*self.invert(self(r))**-1
if not k in K:
gens.append(k)
if isinstance(G, PermutationGroup):
K = PermutationGroup(gens)
else:
K = FpSubgroup(G, gens, normal=True)
return K
def image(self):
'''
Compute the image of `self`.
'''
if self._image is None:
values = list(set(self.images.values()))
if isinstance(self.codomain, PermutationGroup):
self._image = self.codomain.subgroup(values)
else:
self._image = FpSubgroup(self.codomain, values)
return self._image
def _apply(self, elem):
'''
Apply `self` to `elem`.
'''
if not elem in self.domain:
if isinstance(elem, (list, tuple)):
return [self._apply(e) for e in elem]
raise ValueError("The supplied element doesn't belong to the domain")
if elem.is_identity:
return self.codomain.identity
else:
images = self.images
value = self.codomain.identity
if isinstance(self.domain, PermutationGroup):
gens = self.domain.generator_product(elem, original=True)
for g in gens:
if g in self.images:
value = images[g]*value
else:
value = images[g**-1]**-1*value
else:
i = 0
for _, p in elem.array_form:
if p < 0:
g = elem[i]**-1
else:
g = elem[i]
value = value*images[g]**p
i += abs(p)
return value
def __call__(self, elem):
return self._apply(elem)
def is_injective(self):
'''
Check if the homomorphism is injective
'''
return self.kernel().order() == 1
def is_surjective(self):
'''
Check if the homomorphism is surjective
'''
from sympy import S
im = self.image().order()
oth = self.codomain.order()
if im == S.Infinity and oth == S.Infinity:
return None
else:
return im == oth
def is_isomorphism(self):
'''
Check if `self` is an isomorphism.
'''
return self.is_injective() and self.is_surjective()
def is_trivial(self):
'''
Check is `self` is a trivial homomorphism, i.e. all elements
are mapped to the identity.
'''
return self.image().order() == 1
def compose(self, other):
'''
Return the composition of `self` and `other`, i.e.
the homomorphism phi such that for all g in the domain
of `other`, phi(g) = self(other(g))
'''
if not other.image().is_subgroup(self.domain):
raise ValueError("The image of `other` must be a subgroup of "
"the domain of `self`")
images = {g: self(other(g)) for g in other.images}
return GroupHomomorphism(other.domain, self.codomain, images)
def restrict_to(self, H):
'''
Return the restriction of the homomorphism to the subgroup `H`
of the domain.
'''
if not isinstance(H, PermutationGroup) or not H.is_subgroup(self.domain):
raise ValueError("Given H is not a subgroup of the domain")
domain = H
images = {g: self(g) for g in H.generators}
return GroupHomomorphism(domain, self.codomain, images)
def invert_subgroup(self, H):
'''
Return the subgroup of the domain that is the inverse image
of the subgroup `H` of the homomorphism image
'''
if not H.is_subgroup(self.image()):
raise ValueError("Given H is not a subgroup of the image")
gens = []
P = PermutationGroup(self.image().identity)
for h in H.generators:
h_i = self.invert(h)
if h_i not in P:
gens.append(h_i)
P = PermutationGroup(gens)
for k in self.kernel().generators:
if k*h_i not in P:
gens.append(k*h_i)
P = PermutationGroup(gens)
return P
def homomorphism(domain, codomain, gens, images=[], check=True):
'''
Create (if possible) a group homomorphism from the group `domain`
to the group `codomain` defined by the images of the domain's
generators `gens`. `gens` and `images` can be either lists or tuples
of equal sizes. If `gens` is a proper subset of the group's generators,
the unspecified generators will be mapped to the identity. If the
images are not specified, a trivial homomorphism will be created.
If the given images of the generators do not define a homomorphism,
an exception is raised.
If `check` is `False`, don't check whether the given images actually
define a homomorphism.
'''
if not isinstance(domain, (PermutationGroup, FpGroup, FreeGroup)):
raise TypeError("The domain must be a group")
if not isinstance(codomain, (PermutationGroup, FpGroup, FreeGroup)):
raise TypeError("The codomain must be a group")
generators = domain.generators
if any([g not in generators for g in gens]):
raise ValueError("The supplied generators must be a subset of the domain's generators")
if any([g not in codomain for g in images]):
raise ValueError("The images must be elements of the codomain")
if images and len(images) != len(gens):
raise ValueError("The number of images must be equal to the number of generators")
gens = list(gens)
images = list(images)
images.extend([codomain.identity]*(len(generators)-len(images)))
gens.extend([g for g in generators if g not in gens])
images = dict(zip(gens,images))
if check and not _check_homomorphism(domain, codomain, images):
raise ValueError("The given images do not define a homomorphism")
return GroupHomomorphism(domain, codomain, images)
def _check_homomorphism(domain, codomain, images):
if hasattr(domain, 'relators'):
rels = domain.relators
else:
gens = domain.presentation().generators
rels = domain.presentation().relators
identity = codomain.identity
def _image(r):
if r.is_identity:
return identity
else:
w = identity
r_arr = r.array_form
i = 0
j = 0
# i is the index for r and j is for
# r_arr. r_arr[j] is the tuple (sym, p)
# where sym is the generator symbol
# and p is the power to which it is
# raised while r[i] is a generator
# (not just its symbol) or the inverse of
# a generator - hence the need for
# both indices
while i < len(r):
power = r_arr[j][1]
if isinstance(domain, PermutationGroup):
s = domain.generators[gens.index(r[i])]
else:
s = r[i]
if s in images:
w = w*images[s]**power
else:
w = w*images[s**-1]**power
i += abs(power)
j += 1
return w
for r in rels:
if isinstance(codomain, FpGroup):
s = codomain.equals(_image(r), identity)
if s is None:
# only try to make the rewriting system
# confluent when it can't determine the
# truth of equality otherwise
success = codomain.make_confluent()
s = codomain.equals(_image(r), identity)
if s in None and not success:
raise RuntimeError("Can't determine if the images "
"define a homomorphism. Try increasing "
"the maximum number of rewriting rules "
"(group._rewriting_system.set_max(new_value); "
"the current value is stored in group._rewriting"
"_system.maxeqns)")
else:
s = _image(r).is_identity
if not s:
return False
return True
def orbit_homomorphism(group, omega):
'''
Return the homomorphism induced by the action of the permutation
group `group` on the set `omega` that is closed under the action.
'''
from sympy.combinatorics import Permutation
from sympy.combinatorics.named_groups import SymmetricGroup
codomain = SymmetricGroup(len(omega))
identity = codomain.identity
omega = list(omega)
images = {g: identity*Permutation([omega.index(o^g) for o in omega]) for g in group.generators}
group._schreier_sims(base=omega)
H = GroupHomomorphism(group, codomain, images)
if len(group.basic_stabilizers) > len(omega):
H._kernel = group.basic_stabilizers[len(omega)]
else:
H._kernel = PermutationGroup([group.identity])
return H
def block_homomorphism(group, blocks):
'''
Return the homomorphism induced by the action of the permutation
group `group` on the block system `blocks`. The latter should be
of the same form as returned by the `minimal_block` method for
permutation groups, namely a list of length `group.degree` where
the i-th entry is a representative of the block i belongs to.
'''
from sympy.combinatorics import Permutation
from sympy.combinatorics.named_groups import SymmetricGroup
n = len(blocks)
# number the blocks; m is the total number,
# b is such that b[i] is the number of the block i belongs to,
# p is the list of length m such that p[i] is the representative
# of the i-th block
m = 0
p = []
b = [None]*n
for i in range(n):
if blocks[i] == i:
p.append(i)
b[i] = m
m += 1
for i in range(n):
b[i] = b[blocks[i]]
codomain = SymmetricGroup(m)
# the list corresponding to the identity permutation in codomain
identity = range(m)
images = {g: Permutation([b[p[i]^g] for i in identity]) for g in group.generators}
H = GroupHomomorphism(group, codomain, images)
return H
def group_isomorphism(G, H, isomorphism=True):
'''
Compute an isomorphism between 2 given groups.
Parameters
==========
G (a finite `FpGroup` or a `PermutationGroup`) -- First group
H (a finite `FpGroup` or a `PermutationGroup`) -- Second group
isomorphism (boolean) -- This is used to avoid the computation of homomorphism
when the user only wants to check if there exists
an isomorphism between the groups.
Returns
=======
If isomorphism = False -- Returns a boolean.
If isomorphism = True -- Returns a boolean and an isomorphism between `G` and `H`.
Examples
========
>>> from sympy.combinatorics import Permutation
>>> Permutation.print_cyclic = True
>>> from sympy.combinatorics.perm_groups import PermutationGroup
>>> from sympy.combinatorics.free_groups import free_group
>>> from sympy.combinatorics.fp_groups import FpGroup
>>> from sympy.combinatorics.homomorphisms import homomorphism, group_isomorphism
>>> from sympy.combinatorics.named_groups import DihedralGroup, AlternatingGroup
>>> D = DihedralGroup(8)
>>> p = Permutation(0, 1, 2, 3, 4, 5, 6, 7)
>>> P = PermutationGroup(p)
>>> group_isomorphism(D, P)
(False, None)
>>> F, a, b = free_group("a, b")
>>> G = FpGroup(F, [a**3, b**3, (a*b)**2])
>>> H = AlternatingGroup(4)
>>> (check, T) = group_isomorphism(G, H)
>>> check
True
>>> T(b*a*b**-1*a**-1*b**-1)
(0 2 3)
Notes
=====
Uses the approach suggested by Robert Tarjan to compute the isomorphism between two groups.
First, the generators of `G` are mapped to the elements of `H` and
we check if the mapping induces an isomorphism.
'''
if not isinstance(G, (PermutationGroup, FpGroup)):
raise TypeError("The group must be a PermutationGroup or an FpGroup")
if not isinstance(H, (PermutationGroup, FpGroup)):
raise TypeError("The group must be a PermutationGroup or an FpGroup")
if isinstance(G, FpGroup) and isinstance(H, FpGroup):
G = simplify_presentation(G)
H = simplify_presentation(H)
# Two infinite FpGroups with the same generators are isomorphic
# when the relators are same but are ordered differently.
if G.generators == H.generators and (G.relators).sort() == (H.relators).sort():
if not isomorphism:
return True
return (True, homomorphism(G, H, G.generators, H.generators))
# `_H` is the permutation group isomorphic to `H`.
_H = H
g_order = G.order()
h_order = H.order()
if g_order == S.Infinity:
raise NotImplementedError("Isomorphism methods are not implemented for infinite groups.")
if isinstance(H, FpGroup):
if h_order == S.Infinity:
raise NotImplementedError("Isomorphism methods are not implemented for infinite groups.")
_H, h_isomorphism = H._to_perm_group()
if (g_order != h_order) or (G.is_abelian != H.is_abelian):
if not isomorphism:
return False
return (False, None)
if not isomorphism:
# Two groups of the same cyclic numbered order
# are isomorphic to each other.
n = g_order
if (igcd(n, totient(n))) == 1:
return True
# Match the generators of `G` with subsets of `_H`
gens = list(G.generators)
for subset in itertools.permutations(_H, len(gens)):
images = list(subset)
images.extend([_H.identity]*(len(G.generators)-len(images)))
_images = dict(zip(gens,images))
if _check_homomorphism(G, _H, _images):
if isinstance(H, FpGroup):
images = h_isomorphism.invert(images)
T = homomorphism(G, H, G.generators, images, check=False)
if T.is_isomorphism():
# It is a valid isomorphism
if not isomorphism:
return True
return (True, T)
if not isomorphism:
return False
return (False, None)
def is_isomorphic(G, H):
'''
Check if the groups are isomorphic to each other
Parameters
==========
G (a finite `FpGroup` or a `PermutationGroup`) -- First group
H (a finite `FpGroup` or a `PermutationGroup`) -- Second group
Returns
=======
boolean
'''
return group_isomorphism(G, H, isomorphism=False)
|
2bcc2e524a95dda9d3bf6a277f5b7eb1ef9bea6799e44736940ae04d12d9b22a
|
from __future__ import print_function, division
from sympy.combinatorics.permutations import Permutation, _af_invert, _af_rmul
from sympy.core.compatibility import range
from sympy.ntheory import isprime
rmul = Permutation.rmul
_af_new = Permutation._af_new
############################################
#
# Utilities for computational group theory
#
############################################
def _base_ordering(base, degree):
r"""
Order `\{0, 1, ..., n-1\}` so that base points come first and in order.
Parameters
==========
``base`` - the base
``degree`` - the degree of the associated permutation group
Returns
=======
A list ``base_ordering`` such that ``base_ordering[point]`` is the
number of ``point`` in the ordering.
Examples
========
>>> from sympy.combinatorics.named_groups import SymmetricGroup
>>> from sympy.combinatorics.util import _base_ordering
>>> S = SymmetricGroup(4)
>>> S.schreier_sims()
>>> _base_ordering(S.base, S.degree)
[0, 1, 2, 3]
Notes
=====
This is used in backtrack searches, when we define a relation `<<` on
the underlying set for a permutation group of degree `n`,
`\{0, 1, ..., n-1\}`, so that if `(b_1, b_2, ..., b_k)` is a base we
have `b_i << b_j` whenever `i<j` and `b_i << a` for all
`i\in\{1,2, ..., k\}` and `a` is not in the base. The idea is developed
and applied to backtracking algorithms in [1], pp.108-132. The points
that are not in the base are taken in increasing order.
References
==========
.. [1] Holt, D., Eick, B., O'Brien, E.
"Handbook of computational group theory"
"""
base_len = len(base)
ordering = [0]*degree
for i in range(base_len):
ordering[base[i]] = i
current = base_len
for i in range(degree):
if i not in base:
ordering[i] = current
current += 1
return ordering
def _check_cycles_alt_sym(perm):
"""
Checks for cycles of prime length p with n/2 < p < n-2.
Here `n` is the degree of the permutation. This is a helper function for
the function is_alt_sym from sympy.combinatorics.perm_groups.
Examples
========
>>> from sympy.combinatorics.util import _check_cycles_alt_sym
>>> from sympy.combinatorics.permutations import Permutation
>>> a = Permutation([[0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10], [11, 12]])
>>> _check_cycles_alt_sym(a)
False
>>> b = Permutation([[0, 1, 2, 3, 4, 5, 6], [7, 8, 9, 10]])
>>> _check_cycles_alt_sym(b)
True
See Also
========
sympy.combinatorics.perm_groups.PermutationGroup.is_alt_sym
"""
n = perm.size
af = perm.array_form
current_len = 0
total_len = 0
used = set()
for i in range(n//2):
if not i in used and i < n//2 - total_len:
current_len = 1
used.add(i)
j = i
while(af[j] != i):
current_len += 1
j = af[j]
used.add(j)
total_len += current_len
if current_len > n//2 and current_len < n - 2 and isprime(current_len):
return True
return False
def _distribute_gens_by_base(base, gens):
r"""
Distribute the group elements ``gens`` by membership in basic stabilizers.
Notice that for a base `(b_1, b_2, ..., b_k)`, the basic stabilizers
are defined as `G^{(i)} = G_{b_1, ..., b_{i-1}}` for
`i \in\{1, 2, ..., k\}`.
Parameters
==========
``base`` - a sequence of points in `\{0, 1, ..., n-1\}`
``gens`` - a list of elements of a permutation group of degree `n`.
Returns
=======
List of length `k`, where `k` is
the length of ``base``. The `i`-th entry contains those elements in
``gens`` which fix the first `i` elements of ``base`` (so that the
`0`-th entry is equal to ``gens`` itself). If no element fixes the first
`i` elements of ``base``, the `i`-th element is set to a list containing
the identity element.
Examples
========
>>> from sympy.combinatorics import Permutation
>>> Permutation.print_cyclic = True
>>> from sympy.combinatorics.named_groups import DihedralGroup
>>> from sympy.combinatorics.util import _distribute_gens_by_base
>>> D = DihedralGroup(3)
>>> D.schreier_sims()
>>> D.strong_gens
[(0 1 2), (0 2), (1 2)]
>>> D.base
[0, 1]
>>> _distribute_gens_by_base(D.base, D.strong_gens)
[[(0 1 2), (0 2), (1 2)],
[(1 2)]]
See Also
========
_strong_gens_from_distr, _orbits_transversals_from_bsgs,
_handle_precomputed_bsgs
"""
base_len = len(base)
degree = gens[0].size
stabs = [[] for _ in range(base_len)]
max_stab_index = 0
for gen in gens:
j = 0
while j < base_len - 1 and gen._array_form[base[j]] == base[j]:
j += 1
if j > max_stab_index:
max_stab_index = j
for k in range(j + 1):
stabs[k].append(gen)
for i in range(max_stab_index + 1, base_len):
stabs[i].append(_af_new(list(range(degree))))
return stabs
def _handle_precomputed_bsgs(base, strong_gens, transversals=None,
basic_orbits=None, strong_gens_distr=None):
"""
Calculate BSGS-related structures from those present.
The base and strong generating set must be provided; if any of the
transversals, basic orbits or distributed strong generators are not
provided, they will be calculated from the base and strong generating set.
Parameters
==========
``base`` - the base
``strong_gens`` - the strong generators
``transversals`` - basic transversals
``basic_orbits`` - basic orbits
``strong_gens_distr`` - strong generators distributed by membership in basic
stabilizers
Returns
=======
``(transversals, basic_orbits, strong_gens_distr)`` where ``transversals``
are the basic transversals, ``basic_orbits`` are the basic orbits, and
``strong_gens_distr`` are the strong generators distributed by membership
in basic stabilizers.
Examples
========
>>> from sympy.combinatorics import Permutation
>>> Permutation.print_cyclic = True
>>> from sympy.combinatorics.named_groups import DihedralGroup
>>> from sympy.combinatorics.util import _handle_precomputed_bsgs
>>> D = DihedralGroup(3)
>>> D.schreier_sims()
>>> _handle_precomputed_bsgs(D.base, D.strong_gens,
... basic_orbits=D.basic_orbits)
([{0: (2), 1: (0 1 2), 2: (0 2)}, {1: (2), 2: (1 2)}], [[0, 1, 2], [1, 2]], [[(0 1 2), (0 2), (1 2)], [(1 2)]])
See Also
========
_orbits_transversals_from_bsgs, distribute_gens_by_base
"""
if strong_gens_distr is None:
strong_gens_distr = _distribute_gens_by_base(base, strong_gens)
if transversals is None:
if basic_orbits is None:
basic_orbits, transversals = \
_orbits_transversals_from_bsgs(base, strong_gens_distr)
else:
transversals = \
_orbits_transversals_from_bsgs(base, strong_gens_distr,
transversals_only=True)
else:
if basic_orbits is None:
base_len = len(base)
basic_orbits = [None]*base_len
for i in range(base_len):
basic_orbits[i] = list(transversals[i].keys())
return transversals, basic_orbits, strong_gens_distr
def _orbits_transversals_from_bsgs(base, strong_gens_distr,
transversals_only=False, slp=False):
"""
Compute basic orbits and transversals from a base and strong generating set.
The generators are provided as distributed across the basic stabilizers.
If the optional argument ``transversals_only`` is set to True, only the
transversals are returned.
Parameters
==========
``base`` - the base
``strong_gens_distr`` - strong generators distributed by membership in basic
stabilizers
``transversals_only`` - a flag switching between returning only the
transversals/ both orbits and transversals
``slp`` - if ``True``, return a list of dictionaries containing the
generator presentations of the elements of the transversals,
i.e. the list of indices of generators from `strong_gens_distr[i]`
such that their product is the relevant transversal element
Examples
========
>>> from sympy.combinatorics import Permutation
>>> Permutation.print_cyclic = True
>>> from sympy.combinatorics.named_groups import SymmetricGroup
>>> from sympy.combinatorics.util import _orbits_transversals_from_bsgs
>>> from sympy.combinatorics.util import (_orbits_transversals_from_bsgs,
... _distribute_gens_by_base)
>>> S = SymmetricGroup(3)
>>> S.schreier_sims()
>>> strong_gens_distr = _distribute_gens_by_base(S.base, S.strong_gens)
>>> _orbits_transversals_from_bsgs(S.base, strong_gens_distr)
([[0, 1, 2], [1, 2]], [{0: (2), 1: (0 1 2), 2: (0 2 1)}, {1: (2), 2: (1 2)}])
See Also
========
_distribute_gens_by_base, _handle_precomputed_bsgs
"""
from sympy.combinatorics.perm_groups import _orbit_transversal
base_len = len(base)
degree = strong_gens_distr[0][0].size
transversals = [None]*base_len
slps = [None]*base_len
if transversals_only is False:
basic_orbits = [None]*base_len
for i in range(base_len):
transversals[i], slps[i] = _orbit_transversal(degree, strong_gens_distr[i],
base[i], pairs=True, slp=True)
transversals[i] = dict(transversals[i])
if transversals_only is False:
basic_orbits[i] = list(transversals[i].keys())
if transversals_only:
return transversals
else:
if not slp:
return basic_orbits, transversals
return basic_orbits, transversals, slps
def _remove_gens(base, strong_gens, basic_orbits=None, strong_gens_distr=None):
"""
Remove redundant generators from a strong generating set.
Parameters
==========
``base`` - a base
``strong_gens`` - a strong generating set relative to ``base``
``basic_orbits`` - basic orbits
``strong_gens_distr`` - strong generators distributed by membership in basic
stabilizers
Returns
=======
A strong generating set with respect to ``base`` which is a subset of
``strong_gens``.
Examples
========
>>> from sympy.combinatorics.named_groups import SymmetricGroup
>>> from sympy.combinatorics.perm_groups import PermutationGroup
>>> from sympy.combinatorics.util import _remove_gens
>>> from sympy.combinatorics.testutil import _verify_bsgs
>>> S = SymmetricGroup(15)
>>> base, strong_gens = S.schreier_sims_incremental()
>>> new_gens = _remove_gens(base, strong_gens)
>>> len(new_gens)
14
>>> _verify_bsgs(S, base, new_gens)
True
Notes
=====
This procedure is outlined in [1],p.95.
References
==========
.. [1] Holt, D., Eick, B., O'Brien, E.
"Handbook of computational group theory"
"""
from sympy.combinatorics.perm_groups import _orbit
base_len = len(base)
degree = strong_gens[0].size
if strong_gens_distr is None:
strong_gens_distr = _distribute_gens_by_base(base, strong_gens)
if basic_orbits is None:
basic_orbits = []
for i in range(base_len):
basic_orbit = _orbit(degree, strong_gens_distr[i], base[i])
basic_orbits.append(basic_orbit)
strong_gens_distr.append([])
res = strong_gens[:]
for i in range(base_len - 1, -1, -1):
gens_copy = strong_gens_distr[i][:]
for gen in strong_gens_distr[i]:
if gen not in strong_gens_distr[i + 1]:
temp_gens = gens_copy[:]
temp_gens.remove(gen)
if temp_gens == []:
continue
temp_orbit = _orbit(degree, temp_gens, base[i])
if temp_orbit == basic_orbits[i]:
gens_copy.remove(gen)
res.remove(gen)
return res
def _strip(g, base, orbits, transversals):
"""
Attempt to decompose a permutation using a (possibly partial) BSGS
structure.
This is done by treating the sequence ``base`` as an actual base, and
the orbits ``orbits`` and transversals ``transversals`` as basic orbits and
transversals relative to it.
This process is called "sifting". A sift is unsuccessful when a certain
orbit element is not found or when after the sift the decomposition
doesn't end with the identity element.
The argument ``transversals`` is a list of dictionaries that provides
transversal elements for the orbits ``orbits``.
Parameters
==========
``g`` - permutation to be decomposed
``base`` - sequence of points
``orbits`` - a list in which the ``i``-th entry is an orbit of ``base[i]``
under some subgroup of the pointwise stabilizer of `
`base[0], base[1], ..., base[i - 1]``. The groups themselves are implicit
in this function since the only information we need is encoded in the orbits
and transversals
``transversals`` - a list of orbit transversals associated with the orbits
``orbits``.
Examples
========
>>> from sympy.combinatorics import Permutation
>>> Permutation.print_cyclic = True
>>> from sympy.combinatorics.named_groups import SymmetricGroup
>>> from sympy.combinatorics.permutations import Permutation
>>> from sympy.combinatorics.util import _strip
>>> S = SymmetricGroup(5)
>>> S.schreier_sims()
>>> g = Permutation([0, 2, 3, 1, 4])
>>> _strip(g, S.base, S.basic_orbits, S.basic_transversals)
((4), 5)
Notes
=====
The algorithm is described in [1],pp.89-90. The reason for returning
both the current state of the element being decomposed and the level
at which the sifting ends is that they provide important information for
the randomized version of the Schreier-Sims algorithm.
References
==========
[1] Holt, D., Eick, B., O'Brien, E.
"Handbook of computational group theory"
See Also
========
sympy.combinatorics.perm_groups.PermutationGroup.schreier_sims
sympy.combinatorics.perm_groups.PermutationGroup.schreier_sims_random
"""
h = g._array_form
base_len = len(base)
for i in range(base_len):
beta = h[base[i]]
if beta == base[i]:
continue
if beta not in orbits[i]:
return _af_new(h), i + 1
u = transversals[i][beta]._array_form
h = _af_rmul(_af_invert(u), h)
return _af_new(h), base_len + 1
def _strip_af(h, base, orbits, transversals, j, slp=[], slps={}):
"""
optimized _strip, with h, transversals and result in array form
if the stripped elements is the identity, it returns False, base_len + 1
j h[base[i]] == base[i] for i <= j
"""
base_len = len(base)
for i in range(j+1, base_len):
beta = h[base[i]]
if beta == base[i]:
continue
if beta not in orbits[i]:
if not slp:
return h, i + 1
return h, i + 1, slp
u = transversals[i][beta]
if h == u:
if not slp:
return False, base_len + 1
return False, base_len + 1, slp
h = _af_rmul(_af_invert(u), h)
if slp:
u_slp = slps[i][beta][:]
u_slp.reverse()
u_slp = [(i, (g,)) for g in u_slp]
slp = u_slp + slp
if not slp:
return h, base_len + 1
return h, base_len + 1, slp
def _strong_gens_from_distr(strong_gens_distr):
"""
Retrieve strong generating set from generators of basic stabilizers.
This is just the union of the generators of the first and second basic
stabilizers.
Parameters
==========
``strong_gens_distr`` - strong generators distributed by membership in basic
stabilizers
Examples
========
>>> from sympy.combinatorics import Permutation
>>> Permutation.print_cyclic = True
>>> from sympy.combinatorics.named_groups import SymmetricGroup
>>> from sympy.combinatorics.util import (_strong_gens_from_distr,
... _distribute_gens_by_base)
>>> S = SymmetricGroup(3)
>>> S.schreier_sims()
>>> S.strong_gens
[(0 1 2), (2)(0 1), (1 2)]
>>> strong_gens_distr = _distribute_gens_by_base(S.base, S.strong_gens)
>>> _strong_gens_from_distr(strong_gens_distr)
[(0 1 2), (2)(0 1), (1 2)]
See Also
========
_distribute_gens_by_base
"""
if len(strong_gens_distr) == 1:
return strong_gens_distr[0][:]
else:
result = strong_gens_distr[0]
for gen in strong_gens_distr[1]:
if gen not in result:
result.append(gen)
return result
|
055c02a770a0263b8b1111628403faa6eac0e82296e1c98bd462c2d4f221bc65
|
# -*- coding: utf-8 -*-
from __future__ import print_function, division
from sympy.combinatorics.free_groups import free_group
from sympy.printing.defaults import DefaultPrinting
from itertools import chain, product
from bisect import bisect_left
###############################################################################
# COSET TABLE #
###############################################################################
class CosetTable(DefaultPrinting):
# coset_table: Mathematically a coset table
# represented using a list of lists
# alpha: Mathematically a coset (precisely, a live coset)
# represented by an integer between i with 1 <= i <= n
# α ∈ c
# x: Mathematically an element of "A" (set of generators and
# their inverses), represented using "FpGroupElement"
# fp_grp: Finitely Presented Group with < X|R > as presentation.
# H: subgroup of fp_grp.
# NOTE: We start with H as being only a list of words in generators
# of "fp_grp". Since `.subgroup` method has not been implemented.
r"""
Properties
==========
[1] `0 \in \Omega` and `\tau(1) = \epsilon`
[2] `\alpha^x = \beta \Leftrightarrow \beta^{x^{-1}} = \alpha`
[3] If `\alpha^x = \beta`, then `H \tau(\alpha)x = H \tau(\beta)`
[4] `\forall \alpha \in \Omega, 1^{\tau(\alpha)} = \alpha`
References
==========
.. [1] Holt, D., Eick, B., O'Brien, E.
"Handbook of Computational Group Theory"
.. [2] John J. Cannon; Lucien A. Dimino; George Havas; Jane M. Watson
Mathematics of Computation, Vol. 27, No. 123. (Jul., 1973), pp. 463-490.
"Implementation and Analysis of the Todd-Coxeter Algorithm"
"""
# default limit for the number of cosets allowed in a
# coset enumeration.
coset_table_max_limit = 4096000
# limit for the current instance
coset_table_limit = None
# maximum size of deduction stack above or equal to
# which it is emptied
max_stack_size = 100
def __init__(self, fp_grp, subgroup, max_cosets=None):
if not max_cosets:
max_cosets = CosetTable.coset_table_max_limit
self.fp_group = fp_grp
self.subgroup = subgroup
self.coset_table_limit = max_cosets
# "p" is setup independent of Ω and n
self.p = [0]
# a list of the form `[gen_1, gen_1^{-1}, ... , gen_k, gen_k^{-1}]`
self.A = list(chain.from_iterable((gen, gen**-1) \
for gen in self.fp_group.generators))
#P[alpha, x] Only defined when alpha^x is defined.
self.P = [[None]*len(self.A)]
# the mathematical coset table which is a list of lists
self.table = [[None]*len(self.A)]
self.A_dict = {x: self.A.index(x) for x in self.A}
self.A_dict_inv = {}
for x, index in self.A_dict.items():
if index % 2 == 0:
self.A_dict_inv[x] = self.A_dict[x] + 1
else:
self.A_dict_inv[x] = self.A_dict[x] - 1
# used in the coset-table based method of coset enumeration. Each of
# the element is called a "deduction" which is the form (α, x) whenever
# a value is assigned to α^x during a definition or "deduction process"
self.deduction_stack = []
# Attributes for modified methods.
H = self.subgroup
self._grp = free_group(', ' .join(["a_%d" % i for i in range(len(H))]))[0]
self.P = [[None]*len(self.A)]
self.p_p = {}
@property
def omega(self):
"""Set of live cosets. """
return [coset for coset in range(len(self.p)) if self.p[coset] == coset]
def copy(self):
"""
Return a shallow copy of Coset Table instance ``self``.
"""
self_copy = self.__class__(self.fp_group, self.subgroup)
self_copy.table = [list(perm_rep) for perm_rep in self.table]
self_copy.p = list(self.p)
self_copy.deduction_stack = list(self.deduction_stack)
return self_copy
def __str__(self):
return "Coset Table on %s with %s as subgroup generators" \
% (self.fp_group, self.subgroup)
__repr__ = __str__
@property
def n(self):
"""The number `n` represents the length of the sublist containing the
live cosets.
"""
if not self.table:
return 0
return max(self.omega) + 1
# Pg. 152 [1]
def is_complete(self):
r"""
The coset table is called complete if it has no undefined entries
on the live cosets; that is, `\alpha^x` is defined for all
`\alpha \in \Omega` and `x \in A`.
"""
return not any(None in self.table[coset] for coset in self.omega)
# Pg. 153 [1]
def define(self, alpha, x, modified=False):
r"""
This routine is used in the relator-based strategy of Todd-Coxeter
algorithm if some `\alpha^x` is undefined. We check whether there is
space available for defining a new coset. If there is enough space
then we remedy this by adjoining a new coset `\beta` to `\Omega`
(i.e to set of live cosets) and put that equal to `\alpha^x`, then
make an assignment satisfying Property[1]. If there is not enough space
then we halt the Coset Table creation. The maximum amount of space that
can be used by Coset Table can be manipulated using the class variable
``CosetTable.coset_table_max_limit``.
See Also
========
define_c
"""
A = self.A
table = self.table
len_table = len(table)
if len_table >= self.coset_table_limit:
# abort the further generation of cosets
raise ValueError("the coset enumeration has defined more than "
"%s cosets. Try with a greater value max number of cosets "
% self.coset_table_limit)
table.append([None]*len(A))
self.P.append([None]*len(self.A))
# beta is the new coset generated
beta = len_table
self.p.append(beta)
table[alpha][self.A_dict[x]] = beta
table[beta][self.A_dict_inv[x]] = alpha
# P[alpha][x] = epsilon, P[beta][x**-1] = epsilon
if modified:
self.P[alpha][self.A_dict[x]] = self._grp.identity
self.P[beta][self.A_dict_inv[x]] = self._grp.identity
self.p_p[beta] = self._grp.identity
def define_c(self, alpha, x):
r"""
A variation of ``define`` routine, described on Pg. 165 [1], used in
the coset table-based strategy of Todd-Coxeter algorithm. It differs
from ``define`` routine in that for each definition it also adds the
tuple `(\alpha, x)` to the deduction stack.
See Also
========
define
"""
A = self.A
table = self.table
len_table = len(table)
if len_table >= self.coset_table_limit:
# abort the further generation of cosets
raise ValueError("the coset enumeration has defined more than "
"%s cosets. Try with a greater value max number of cosets "
% self.coset_table_limit)
table.append([None]*len(A))
# beta is the new coset generated
beta = len_table
self.p.append(beta)
table[alpha][self.A_dict[x]] = beta
table[beta][self.A_dict_inv[x]] = alpha
# append to deduction stack
self.deduction_stack.append((alpha, x))
def scan_c(self, alpha, word):
"""
A variation of ``scan`` routine, described on pg. 165 of [1], which
puts at tuple, whenever a deduction occurs, to deduction stack.
See Also
========
scan, scan_check, scan_and_fill, scan_and_fill_c
"""
# α is an integer representing a "coset"
# since scanning can be in two cases
# 1. for α=0 and w in Y (i.e generating set of H)
# 2. α in Ω (set of live cosets), w in R (relators)
A_dict = self.A_dict
A_dict_inv = self.A_dict_inv
table = self.table
f = alpha
i = 0
r = len(word)
b = alpha
j = r - 1
# list of union of generators and their inverses
while i <= j and table[f][A_dict[word[i]]] is not None:
f = table[f][A_dict[word[i]]]
i += 1
if i > j:
if f != b:
self.coincidence_c(f, b)
return
while j >= i and table[b][A_dict_inv[word[j]]] is not None:
b = table[b][A_dict_inv[word[j]]]
j -= 1
if j < i:
# we have an incorrect completed scan with coincidence f ~ b
# run the "coincidence" routine
self.coincidence_c(f, b)
elif j == i:
# deduction process
table[f][A_dict[word[i]]] = b
table[b][A_dict_inv[word[i]]] = f
self.deduction_stack.append((f, word[i]))
# otherwise scan is incomplete and yields no information
# α, β coincide, i.e. α, β represent the pair of cosets where
# coincidence occurs
def coincidence_c(self, alpha, beta):
"""
A variation of ``coincidence`` routine used in the coset-table based
method of coset enumeration. The only difference being on addition of
a new coset in coset table(i.e new coset introduction), then it is
appended to ``deduction_stack``.
See Also
========
coincidence
"""
A_dict = self.A_dict
A_dict_inv = self.A_dict_inv
table = self.table
# behaves as a queue
q = []
self.merge(alpha, beta, q)
while len(q) > 0:
gamma = q.pop(0)
for x in A_dict:
delta = table[gamma][A_dict[x]]
if delta is not None:
table[delta][A_dict_inv[x]] = None
# only line of difference from ``coincidence`` routine
self.deduction_stack.append((delta, x**-1))
mu = self.rep(gamma)
nu = self.rep(delta)
if table[mu][A_dict[x]] is not None:
self.merge(nu, table[mu][A_dict[x]], q)
elif table[nu][A_dict_inv[x]] is not None:
self.merge(mu, table[nu][A_dict_inv[x]], q)
else:
table[mu][A_dict[x]] = nu
table[nu][A_dict_inv[x]] = mu
def scan(self, alpha, word, y=None, fill=False, modified=False):
r"""
``scan`` performs a scanning process on the input ``word``.
It first locates the largest prefix ``s`` of ``word`` for which
`\alpha^s` is defined (i.e is not ``None``), ``s`` may be empty. Let
``word=sv``, let ``t`` be the longest suffix of ``v`` for which
`\alpha^{t^{-1}}` is defined, and let ``v=ut``. Then three
possibilities are there:
1. If ``t=v``, then we say that the scan completes, and if, in addition
`\alpha^s = \alpha^{t^{-1}}`, then we say that the scan completes
correctly.
2. It can also happen that scan does not complete, but `|u|=1`; that
is, the word ``u`` consists of a single generator `x \in A`. In that
case, if `\alpha^s = \beta` and `\alpha^{t^{-1}} = \gamma`, then we can
set `\beta^x = \gamma` and `\gamma^{x^{-1}} = \beta`. These assignments
are known as deductions and enable the scan to complete correctly.
3. See ``coicidence`` routine for explanation of third condition.
Notes
=====
The code for the procedure of scanning `\alpha \in \Omega`
under `w \in A*` is defined on pg. 155 [1]
See Also
========
scan_c, scan_check, scan_and_fill, scan_and_fill_c
Scan and Fill
=============
Performed when the default argument fill=True.
Modified Scan
=============
Performed when the default argument modified=True
"""
# α is an integer representing a "coset"
# since scanning can be in two cases
# 1. for α=0 and w in Y (i.e generating set of H)
# 2. α in Ω (set of live cosets), w in R (relators)
A_dict = self.A_dict
A_dict_inv = self.A_dict_inv
table = self.table
f = alpha
i = 0
r = len(word)
b = alpha
j = r - 1
b_p = y
if modified:
f_p = self._grp.identity
flag = 0
while fill or flag == 0:
flag = 1
while i <= j and table[f][A_dict[word[i]]] is not None:
if modified:
f_p = f_p*self.P[f][A_dict[word[i]]]
f = table[f][A_dict[word[i]]]
i += 1
if i > j:
if f != b:
if modified:
self.modified_coincidence(f, b, f_p**-1*y)
else:
self.coincidence(f, b)
return
while j >= i and table[b][A_dict_inv[word[j]]] is not None:
if modified:
b_p = b_p*self.P[b][self.A_dict_inv[word[j]]]
b = table[b][A_dict_inv[word[j]]]
j -= 1
if j < i:
# we have an incorrect completed scan with coincidence f ~ b
# run the "coincidence" routine
if modified:
self.modified_coincidence(f, b, f_p**-1*b_p)
else:
self.coincidence(f, b)
elif j == i:
# deduction process
table[f][A_dict[word[i]]] = b
table[b][A_dict_inv[word[i]]] = f
if modified:
self.P[f][self.A_dict[word[i]]] = f_p**-1*b_p
self.P[b][self.A_dict_inv[word[i]]] = b_p**-1*f_p
return
elif fill:
self.define(f, word[i], modified=modified)
# otherwise scan is incomplete and yields no information
# used in the low-index subgroups algorithm
def scan_check(self, alpha, word):
r"""
Another version of ``scan`` routine, described on, it checks whether
`\alpha` scans correctly under `word`, it is a straightforward
modification of ``scan``. ``scan_check`` returns ``False`` (rather than
calling ``coincidence``) if the scan completes incorrectly; otherwise
it returns ``True``.
See Also
========
scan, scan_c, scan_and_fill, scan_and_fill_c
"""
# α is an integer representing a "coset"
# since scanning can be in two cases
# 1. for α=0 and w in Y (i.e generating set of H)
# 2. α in Ω (set of live cosets), w in R (relators)
A_dict = self.A_dict
A_dict_inv = self.A_dict_inv
table = self.table
f = alpha
i = 0
r = len(word)
b = alpha
j = r - 1
while i <= j and table[f][A_dict[word[i]]] is not None:
f = table[f][A_dict[word[i]]]
i += 1
if i > j:
return f == b
while j >= i and table[b][A_dict_inv[word[j]]] is not None:
b = table[b][A_dict_inv[word[j]]]
j -= 1
if j < i:
# we have an incorrect completed scan with coincidence f ~ b
# return False, instead of calling coincidence routine
return False
elif j == i:
# deduction process
table[f][A_dict[word[i]]] = b
table[b][A_dict_inv[word[i]]] = f
return True
def merge(self, k, lamda, q, w=None, modified=False):
"""
Merge two classes with representatives ``k`` and ``lamda``, described
on Pg. 157 [1] (for pseudocode), start by putting ``p[k] = lamda``.
It is more efficient to choose the new representative from the larger
of the two classes being merged, i.e larger among ``k`` and ``lamda``.
procedure ``merge`` performs the merging operation, adds the deleted
class representative to the queue ``q``.
Parameters
==========
'k', 'lamda' being the two class representatives to be merged.
Notes
=====
Pg. 86-87 [1] contains a description of this method.
See Also
========
coincidence, rep
"""
p = self.p
rep = self.rep
phi = rep(k, modified=modified)
psi = rep(lamda, modified=modified)
if phi != psi:
mu = min(phi, psi)
v = max(phi, psi)
p[v] = mu
if modified:
if v == phi:
self.p_p[phi] = self.p_p[k]**-1*w*self.p_p[lamda]
else:
self.p_p[psi] = self.p_p[lamda]**-1*w**-1*self.p_p[k]
q.append(v)
def rep(self, k, modified=False):
r"""
Parameters
==========
`k \in [0 \ldots n-1]`, as for ``self`` only array ``p`` is used
Returns
=======
Representative of the class containing ``k``.
Returns the representative of `\sim` class containing ``k``, it also
makes some modification to array ``p`` of ``self`` to ease further
computations, described on Pg. 157 [1].
The information on classes under `\sim` is stored in array `p` of
``self`` argument, which will always satisfy the property:
`p[\alpha] \sim \alpha` and `p[\alpha]=\alpha \iff \alpha=rep(\alpha)`
`\forall \in [0 \ldots n-1]`.
So, for `\alpha \in [0 \ldots n-1]`, we find `rep(self, \alpha)` by
continually replacing `\alpha` by `p[\alpha]` until it becomes
constant (i.e satisfies `p[\alpha] = \alpha`):w
To increase the efficiency of later ``rep`` calculations, whenever we
find `rep(self, \alpha)=\beta`, we set
`p[\gamma] = \beta \forall \gamma \in p-chain` from `\alpha` to `\beta`
Notes
=====
``rep`` routine is also described on Pg. 85-87 [1] in Atkinson's
algorithm, this results from the fact that ``coincidence`` routine
introduces functionality similar to that introduced by the
``minimal_block`` routine on Pg. 85-87 [1].
See Also
========
coincidence, merge
"""
p = self.p
lamda = k
rho = p[lamda]
if modified:
s = p[:]
while rho != lamda:
if modified:
s[rho] = lamda
lamda = rho
rho = p[lamda]
if modified:
rho = s[lamda]
while rho != k:
mu = rho
rho = s[mu]
p[rho] = lamda
self.p_p[rho] = self.p_p[rho]*self.p_p[mu]
else:
mu = k
rho = p[mu]
while rho != lamda:
p[mu] = lamda
mu = rho
rho = p[mu]
return lamda
# α, β coincide, i.e. α, β represent the pair of cosets
# where coincidence occurs
def coincidence(self, alpha, beta, w=None, modified=False):
r"""
The third situation described in ``scan`` routine is handled by this
routine, described on Pg. 156-161 [1].
The unfortunate situation when the scan completes but not correctly,
then ``coincidence`` routine is run. i.e when for some `i` with
`1 \le i \le r+1`, we have `w=st` with `s=x_1*x_2 ... x_{i-1}`,
`t=x_i*x_{i+1} ... x_r`, and `\beta = \alpha^s` and
`\gamma = \alph^{t-1}` are defined but unequal. This means that
`\beta` and `\gamma` represent the same coset of `H` in `G`. Described
on Pg. 156 [1]. ``rep``
See Also
========
scan
"""
A_dict = self.A_dict
A_dict_inv = self.A_dict_inv
table = self.table
# behaves as a queue
q = []
if modified:
self.modified_merge(alpha, beta, w, q)
else:
self.merge(alpha, beta, q)
while len(q) > 0:
gamma = q.pop(0)
for x in A_dict:
delta = table[gamma][A_dict[x]]
if delta is not None:
table[delta][A_dict_inv[x]] = None
mu = self.rep(gamma, modified=modified)
nu = self.rep(delta, modified=modified)
if table[mu][A_dict[x]] is not None:
if modified:
v = self.p_p[delta]**-1*self.P[gamma][self.A_dict[x]]**-1
v = v*self.p_p[gamma]*self.P[mu][self.A_dict[x]]
self.modified_merge(nu, table[mu][self.A_dict[x]], v, q)
else:
self.merge(nu, table[mu][A_dict[x]], q)
elif table[nu][A_dict_inv[x]] is not None:
if modified:
v = self.p_p[gamma]**-1*self.P[gamma][self.A_dict[x]]
v = v*self.p_p[delta]*self.P[mu][self.A_dict_inv[x]]
self.modified_merge(mu, table[nu][self.A_dict_inv[x]], v, q)
else:
self.merge(mu, table[nu][A_dict_inv[x]], q)
else:
table[mu][A_dict[x]] = nu
table[nu][A_dict_inv[x]] = mu
if modified:
v = self.p_p[gamma]**-1*self.P[gamma][self.A_dict[x]]*self.p_p[delta]
self.P[mu][self.A_dict[x]] = v
self.P[nu][self.A_dict_inv[x]] = v**-1
# method used in the HLT strategy
def scan_and_fill(self, alpha, word):
"""
A modified version of ``scan`` routine used in the relator-based
method of coset enumeration, described on pg. 162-163 [1], which
follows the idea that whenever the procedure is called and the scan
is incomplete then it makes new definitions to enable the scan to
complete; i.e it fills in the gaps in the scan of the relator or
subgroup generator.
"""
self.scan(alpha, word, fill=True)
def scan_and_fill_c(self, alpha, word):
"""
A modified version of ``scan`` routine, described on Pg. 165 second
para. [1], with modification similar to that of ``scan_anf_fill`` the
only difference being it calls the coincidence procedure used in the
coset-table based method i.e. the routine ``coincidence_c`` is used.
See Also
========
scan, scan_and_fill
"""
A_dict = self.A_dict
A_dict_inv = self.A_dict_inv
table = self.table
r = len(word)
f = alpha
i = 0
b = alpha
j = r - 1
# loop until it has filled the α row in the table.
while True:
# do the forward scanning
while i <= j and table[f][A_dict[word[i]]] is not None:
f = table[f][A_dict[word[i]]]
i += 1
if i > j:
if f != b:
self.coincidence_c(f, b)
return
# forward scan was incomplete, scan backwards
while j >= i and table[b][A_dict_inv[word[j]]] is not None:
b = table[b][A_dict_inv[word[j]]]
j -= 1
if j < i:
self.coincidence_c(f, b)
elif j == i:
table[f][A_dict[word[i]]] = b
table[b][A_dict_inv[word[i]]] = f
self.deduction_stack.append((f, word[i]))
else:
self.define_c(f, word[i])
# method used in the HLT strategy
def look_ahead(self):
"""
When combined with the HLT method this is known as HLT+Lookahead
method of coset enumeration, described on pg. 164 [1]. Whenever
``define`` aborts due to lack of space available this procedure is
executed. This routine helps in recovering space resulting from
"coincidence" of cosets.
"""
R = self.fp_group.relators
p = self.p
# complete scan all relators under all cosets(obviously live)
# without making new definitions
for beta in self.omega:
for w in R:
self.scan(beta, w)
if p[beta] < beta:
break
# Pg. 166
def process_deductions(self, R_c_x, R_c_x_inv):
"""
Processes the deductions that have been pushed onto ``deduction_stack``,
described on Pg. 166 [1] and is used in coset-table based enumeration.
See Also
========
deduction_stack
"""
p = self.p
table = self.table
while len(self.deduction_stack) > 0:
if len(self.deduction_stack) >= CosetTable.max_stack_size:
self.look_ahead()
del self.deduction_stack[:]
continue
else:
alpha, x = self.deduction_stack.pop()
if p[alpha] == alpha:
for w in R_c_x:
self.scan_c(alpha, w)
if p[alpha] < alpha:
break
beta = table[alpha][self.A_dict[x]]
if beta is not None and p[beta] == beta:
for w in R_c_x_inv:
self.scan_c(beta, w)
if p[beta] < beta:
break
def process_deductions_check(self, R_c_x, R_c_x_inv):
"""
A variation of ``process_deductions``, this calls ``scan_check``
wherever ``process_deductions`` calls ``scan``, described on Pg. [1].
See Also
========
process_deductions
"""
table = self.table
while len(self.deduction_stack) > 0:
alpha, x = self.deduction_stack.pop()
for w in R_c_x:
if not self.scan_check(alpha, w):
return False
beta = table[alpha][self.A_dict[x]]
if beta is not None:
for w in R_c_x_inv:
if not self.scan_check(beta, w):
return False
return True
def switch(self, beta, gamma):
r"""Switch the elements `\beta, \gamma \in \Omega` of ``self``, used
by the ``standardize`` procedure, described on Pg. 167 [1].
See Also
========
standardize
"""
A = self.A
A_dict = self.A_dict
table = self.table
for x in A:
z = table[gamma][A_dict[x]]
table[gamma][A_dict[x]] = table[beta][A_dict[x]]
table[beta][A_dict[x]] = z
for alpha in range(len(self.p)):
if self.p[alpha] == alpha:
if table[alpha][A_dict[x]] == beta:
table[alpha][A_dict[x]] = gamma
elif table[alpha][A_dict[x]] == gamma:
table[alpha][A_dict[x]] = beta
def standardize(self):
r"""
A coset table is standardized if when running through the cosets and
within each coset through the generator images (ignoring generator
inverses), the cosets appear in order of the integers
`0, 1, , \ldots, n`. "Standardize" reorders the elements of `\Omega`
such that, if we scan the coset table first by elements of `\Omega`
and then by elements of A, then the cosets occur in ascending order.
``standardize()`` is used at the end of an enumeration to permute the
cosets so that they occur in some sort of standard order.
Notes
=====
procedure is described on pg. 167-168 [1], it also makes use of the
``switch`` routine to replace by smaller integer value.
Examples
========
>>> from sympy.combinatorics.free_groups import free_group
>>> from sympy.combinatorics.fp_groups import FpGroup, coset_enumeration_r
>>> F, x, y = free_group("x, y")
# Example 5.3 from [1]
>>> f = FpGroup(F, [x**2*y**2, x**3*y**5])
>>> C = coset_enumeration_r(f, [])
>>> C.compress()
>>> C.table
[[1, 3, 1, 3], [2, 0, 2, 0], [3, 1, 3, 1], [0, 2, 0, 2]]
>>> C.standardize()
>>> C.table
[[1, 2, 1, 2], [3, 0, 3, 0], [0, 3, 0, 3], [2, 1, 2, 1]]
"""
A = self.A
A_dict = self.A_dict
gamma = 1
for alpha, x in product(range(self.n), A):
beta = self.table[alpha][A_dict[x]]
if beta >= gamma:
if beta > gamma:
self.switch(gamma, beta)
gamma += 1
if gamma == self.n:
return
# Compression of a Coset Table
def compress(self):
"""Removes the non-live cosets from the coset table, described on
pg. 167 [1].
"""
gamma = -1
A = self.A
A_dict = self.A_dict
A_dict_inv = self.A_dict_inv
table = self.table
chi = tuple([i for i in range(len(self.p)) if self.p[i] != i])
for alpha in self.omega:
gamma += 1
if gamma != alpha:
# replace α by γ in coset table
for x in A:
beta = table[alpha][A_dict[x]]
table[gamma][A_dict[x]] = beta
table[beta][A_dict_inv[x]] == gamma
# all the cosets in the table are live cosets
self.p = list(range(gamma + 1))
# delete the useless columns
del table[len(self.p):]
# re-define values
for row in table:
for j in range(len(self.A)):
row[j] -= bisect_left(chi, row[j])
def conjugates(self, R):
R_c = list(chain.from_iterable((rel.cyclic_conjugates(), \
(rel**-1).cyclic_conjugates()) for rel in R))
R_set = set()
for conjugate in R_c:
R_set = R_set.union(conjugate)
R_c_list = []
for x in self.A:
r = set([word for word in R_set if word[0] == x])
R_c_list.append(r)
R_set.difference_update(r)
return R_c_list
def coset_representative(self, coset):
'''
Compute the coset representative of a given coset.
Examples
========
>>> from sympy.combinatorics.free_groups import free_group
>>> from sympy.combinatorics.fp_groups import FpGroup, coset_enumeration_r
>>> F, x, y = free_group("x, y")
>>> f = FpGroup(F, [x**3, y**3, x**-1*y**-1*x*y])
>>> C = coset_enumeration_r(f, [x])
>>> C.compress()
>>> C.table
[[0, 0, 1, 2], [1, 1, 2, 0], [2, 2, 0, 1]]
>>> C.coset_representative(0)
<identity>
>>> C.coset_representative(1)
y
>>> C.coset_representative(2)
y**-1
'''
for x in self.A:
gamma = self.table[coset][self.A_dict[x]]
if coset == 0:
return self.fp_group.identity
if gamma < coset:
return self.coset_representative(gamma)*x**-1
##############################
# Modified Methods #
##############################
def modified_define(self, alpha, x):
r"""
Define a function p_p from from [1..n] to A* as
an additional component of the modified coset table.
Parameters
==========
\alpha \in \Omega
x \in A*
See Also
========
define
"""
self.define(alpha, x, modified=True)
def modified_scan(self, alpha, w, y, fill=False):
r"""
Parameters
==========
\alpha \in \Omega
w \in A*
y \in (YUY^-1)
fill -- `modified_scan_and_fill` when set to True.
See Also
========
scan
"""
self.scan(alpha, w, y=y, fill=fill, modified=True)
def modified_scan_and_fill(self, alpha, w, y):
self.modified_scan(alpha, w, y, fill=True)
def modified_merge(self, k, lamda, w, q):
r"""
Parameters
==========
'k', 'lamda' -- the two class representatives to be merged.
q -- queue of length l of elements to be deleted from Ω *.
w -- Word in (YUY^-1)
See Also
========
merge
"""
self.merge(k, lamda, q, w=w, modified=True)
def modified_rep(self, k):
r"""
Parameters
==========
`k \in [0 \ldots n-1]`
See Also
========
rep
"""
self.rep(k, modified=True)
def modified_coincidence(self, alpha, beta, w):
r"""
Parameters
==========
A coincident pair \alpha,\beta \in \Omega, w \in (Y∪Y^–1)
See Also
========
coincidence
"""
self.coincidence(alpha, beta, w=w, modified=True)
###############################################################################
# COSET ENUMERATION #
###############################################################################
# relator-based method
def coset_enumeration_r(fp_grp, Y, max_cosets=None, draft=None,
incomplete=False, modified=False):
"""
This is easier of the two implemented methods of coset enumeration.
and is often called the HLT method, after Hazelgrove, Leech, Trotter
The idea is that we make use of ``scan_and_fill`` makes new definitions
whenever the scan is incomplete to enable the scan to complete; this way
we fill in the gaps in the scan of the relator or subgroup generator,
that's why the name relator-based method.
An instance of `CosetTable` for `fp_grp` can be passed as the keyword
argument `draft` in which case the coset enumeration will start with
that instance and attempt to complete it.
When `incomplete` is `True` and the function is unable to complete for
some reason, the partially complete table will be returned.
# TODO: complete the docstring
See Also
========
scan_and_fill,
Examples
========
>>> from sympy.combinatorics.free_groups import free_group
>>> from sympy.combinatorics.fp_groups import FpGroup, coset_enumeration_r
>>> F, x, y = free_group("x, y")
# Example 5.1 from [1]
>>> f = FpGroup(F, [x**3, y**3, x**-1*y**-1*x*y])
>>> C = coset_enumeration_r(f, [x])
>>> for i in range(len(C.p)):
... if C.p[i] == i:
... print(C.table[i])
[0, 0, 1, 2]
[1, 1, 2, 0]
[2, 2, 0, 1]
>>> C.p
[0, 1, 2, 1, 1]
# Example from exercises Q2 [1]
>>> f = FpGroup(F, [x**2*y**2, y**-1*x*y*x**-3])
>>> C = coset_enumeration_r(f, [])
>>> C.compress(); C.standardize()
>>> C.table
[[1, 2, 3, 4],
[5, 0, 6, 7],
[0, 5, 7, 6],
[7, 6, 5, 0],
[6, 7, 0, 5],
[2, 1, 4, 3],
[3, 4, 2, 1],
[4, 3, 1, 2]]
# Example 5.2
>>> f = FpGroup(F, [x**2, y**3, (x*y)**3])
>>> Y = [x*y]
>>> C = coset_enumeration_r(f, Y)
>>> for i in range(len(C.p)):
... if C.p[i] == i:
... print(C.table[i])
[1, 1, 2, 1]
[0, 0, 0, 2]
[3, 3, 1, 0]
[2, 2, 3, 3]
# Example 5.3
>>> f = FpGroup(F, [x**2*y**2, x**3*y**5])
>>> Y = []
>>> C = coset_enumeration_r(f, Y)
>>> for i in range(len(C.p)):
... if C.p[i] == i:
... print(C.table[i])
[1, 3, 1, 3]
[2, 0, 2, 0]
[3, 1, 3, 1]
[0, 2, 0, 2]
# Example 5.4
>>> F, a, b, c, d, e = free_group("a, b, c, d, e")
>>> f = FpGroup(F, [a*b*c**-1, b*c*d**-1, c*d*e**-1, d*e*a**-1, e*a*b**-1])
>>> Y = [a]
>>> C = coset_enumeration_r(f, Y)
>>> for i in range(len(C.p)):
... if C.p[i] == i:
... print(C.table[i])
[0, 0, 0, 0, 0, 0, 0, 0, 0, 0]
# example of "compress" method
>>> C.compress()
>>> C.table
[[0, 0, 0, 0, 0, 0, 0, 0, 0, 0]]
# Exercises Pg. 161, Q2.
>>> F, x, y = free_group("x, y")
>>> f = FpGroup(F, [x**2*y**2, y**-1*x*y*x**-3])
>>> Y = []
>>> C = coset_enumeration_r(f, Y)
>>> C.compress()
>>> C.standardize()
>>> C.table
[[1, 2, 3, 4],
[5, 0, 6, 7],
[0, 5, 7, 6],
[7, 6, 5, 0],
[6, 7, 0, 5],
[2, 1, 4, 3],
[3, 4, 2, 1],
[4, 3, 1, 2]]
# John J. Cannon; Lucien A. Dimino; George Havas; Jane M. Watson
# Mathematics of Computation, Vol. 27, No. 123. (Jul., 1973), pp. 463-490
# from 1973chwd.pdf
# Table 1. Ex. 1
>>> F, r, s, t = free_group("r, s, t")
>>> E1 = FpGroup(F, [t**-1*r*t*r**-2, r**-1*s*r*s**-2, s**-1*t*s*t**-2])
>>> C = coset_enumeration_r(E1, [r])
>>> for i in range(len(C.p)):
... if C.p[i] == i:
... print(C.table[i])
[0, 0, 0, 0, 0, 0]
Ex. 2
>>> F, a, b = free_group("a, b")
>>> Cox = FpGroup(F, [a**6, b**6, (a*b)**2, (a**2*b**2)**2, (a**3*b**3)**5])
>>> C = coset_enumeration_r(Cox, [a])
>>> index = 0
>>> for i in range(len(C.p)):
... if C.p[i] == i:
... index += 1
>>> index
500
# Ex. 3
>>> F, a, b = free_group("a, b")
>>> B_2_4 = FpGroup(F, [a**4, b**4, (a*b)**4, (a**-1*b)**4, (a**2*b)**4, \
(a*b**2)**4, (a**2*b**2)**4, (a**-1*b*a*b)**4, (a*b**-1*a*b)**4])
>>> C = coset_enumeration_r(B_2_4, [a])
>>> index = 0
>>> for i in range(len(C.p)):
... if C.p[i] == i:
... index += 1
>>> index
1024
References
==========
.. [1] Holt, D., Eick, B., O'Brien, E.
"Handbook of computational group theory"
"""
# 1. Initialize a coset table C for < X|R >
C = CosetTable(fp_grp, Y, max_cosets=max_cosets)
# Define coset table methods.
if modified:
_scan_and_fill = C.modified_scan_and_fill
_define = C.modified_define
else:
_scan_and_fill = C.scan_and_fill
_define = C.define
if draft:
C.table = draft.table[:]
C.p = draft.p[:]
R = fp_grp.relators
A_dict = C.A_dict
p = C.p
for i in range(0, len(Y)):
if modified:
_scan_and_fill(0, Y[i], C._grp.generators[i])
else:
_scan_and_fill(0, Y[i])
alpha = 0
while alpha < C.n:
if p[alpha] == alpha:
try:
for w in R:
if modified:
_scan_and_fill(alpha, w, C._grp.identity)
else:
_scan_and_fill(alpha, w)
# if α was eliminated during the scan then break
if p[alpha] < alpha:
break
if p[alpha] == alpha:
for x in A_dict:
if C.table[alpha][A_dict[x]] is None:
_define(alpha, x)
except ValueError as e:
if incomplete:
return C
raise e
alpha += 1
return C
def modified_coset_enumeration_r(fp_grp, Y, max_cosets=None, draft=None,
incomplete=False):
r"""
Introduce a new set of symbols y \in Y that correspond to the
generators of the subgroup. Store the elements of Y as a
word P[\alpha, x] and compute the coset table simlar to that of
the regular coset enumeration methods.
Examples
========
>>> from sympy.combinatorics.free_groups import free_group
>>> from sympy.combinatorics.fp_groups import FpGroup, coset_enumeration_r
>>> from sympy.combinatorics.coset_table import modified_coset_enumeration_r
>>> F, x, y = free_group("x, y")
>>> f = FpGroup(F, [x**3, y**3, x**-1*y**-1*x*y])
>>> C = modified_coset_enumeration_r(f, [x])
>>> C.table
[[0, 0, 1, 2], [1, 1, 2, 0], [2, 2, 0, 1], [None, 1, None, None], [1, 3, None, None]]
See Also
========
coset_enumertation_r
References
==========
.. [1] Holt, D., Eick, B., O'Brien, E.,
"Handbook of Computational Group Theory",
Section 5.3.2
"""
return coset_enumeration_r(fp_grp, Y, max_cosets=max_cosets, draft=draft,
incomplete=incomplete, modified=True)
# Pg. 166
# coset-table based method
def coset_enumeration_c(fp_grp, Y, max_cosets=None, draft=None,
incomplete=False):
"""
>>> from sympy.combinatorics.free_groups import free_group
>>> from sympy.combinatorics.fp_groups import FpGroup, coset_enumeration_c
>>> F, x, y = free_group("x, y")
>>> f = FpGroup(F, [x**3, y**3, x**-1*y**-1*x*y])
>>> C = coset_enumeration_c(f, [x])
>>> C.table
[[0, 0, 1, 2], [1, 1, 2, 0], [2, 2, 0, 1]]
"""
# Initialize a coset table C for < X|R >
X = fp_grp.generators
R = fp_grp.relators
C = CosetTable(fp_grp, Y, max_cosets=max_cosets)
if draft:
C.table = draft.table[:]
C.p = draft.p[:]
C.deduction_stack = draft.deduction_stack
for alpha, x in product(range(len(C.table)), X):
if not C.table[alpha][C.A_dict[x]] is None:
C.deduction_stack.append((alpha, x))
A = C.A
# replace all the elements by cyclic reductions
R_cyc_red = [rel.identity_cyclic_reduction() for rel in R]
R_c = list(chain.from_iterable((rel.cyclic_conjugates(), (rel**-1).cyclic_conjugates()) \
for rel in R_cyc_red))
R_set = set()
for conjugate in R_c:
R_set = R_set.union(conjugate)
# a list of subsets of R_c whose words start with "x".
R_c_list = []
for x in C.A:
r = set([word for word in R_set if word[0] == x])
R_c_list.append(r)
R_set.difference_update(r)
for w in Y:
C.scan_and_fill_c(0, w)
for x in A:
C.process_deductions(R_c_list[C.A_dict[x]], R_c_list[C.A_dict_inv[x]])
alpha = 0
while alpha < len(C.table):
if C.p[alpha] == alpha:
try:
for x in C.A:
if C.p[alpha] != alpha:
break
if C.table[alpha][C.A_dict[x]] is None:
C.define_c(alpha, x)
C.process_deductions(R_c_list[C.A_dict[x]], R_c_list[C.A_dict_inv[x]])
except ValueError as e:
if incomplete:
return C
raise e
alpha += 1
return C
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