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< {\left[ {x},{y} \right]},{\left[ {1},{x^{2}} \right]} \right>"
I = R.ideal(x**2, y)
assert latex(I) == r"\left< {x^{2}},{y} \right>"
Q = F / M
assert latex(
Q
) == r"\frac{{\mathbb{Q}\left[x, y\right]}^{2}}{\left< {\left[ {x},{y} \right]},{\left[ {1},{x^{2}} \right]} \right>}"
assert latex(Q.submodule([1, x**3/2], [2, y])) == \
r"\left< {{\left[ {1},{\frac{x^{3}}{2}} \right]} + {\left< {\left[ {x},{y} \right]},{\left[ {1},{x^{2}} \right]} \right>}},{{\left[ {2},{y} \right]} + {\left< {\left[ {x},{y} \right]},{\left[ {1},{x^{2}} \right]} \right>}} \right>"
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_conversion():
L = QQ.old_poly_ring(x, y, order="ilex")
G = QQ.old_poly_ring(x, y)
assert L.convert(x) == L.convert(G.convert(x), G)
assert G.convert(x) == G.convert(L.convert(x), L)
raises(CoercionFailed, lambda: G.convert(L.convert(1/(1 + x)), L))
def test_conversion():
L = QQ.old_poly_ring(x, y, order="ilex")
G = QQ.old_poly_ring(x, y)
assert L.convert(x) == L.convert(G.convert(x), G)
assert G.convert(x) == G.convert(L.convert(x), L)
raises(CoercionFailed, lambda: G.convert(L.convert(1/(1 + x)), L))
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< {\left[ {x},{y} \right]},{\left[ {1},{x^{2}} \right]} \right>"
I = R.ideal(x ** 2, y)
assert latex(I) == r"\left< {x^{2}},{y} \right>"
Q = F / M
assert (
latex(Q)
== r"\frac{{\mathbb{Q}\left[x, y\right]}^{2}}{\left< {\left[ {x},{y} \right]},{\left[ {1},{x^{2}} \right]} \right>}"
)
assert (
latex(Q.submodule([1, x ** 3 / 2], [2, y]))
== r"\left< {{\left[ {1},{\frac{x^{3}}{2}} \right]} + {\left< {\left[ {x},{y} \right]},{\left[ {1},{x^{2}} \right]} \right>}},{{\left[ {2},{y} \right]} + {\left< {\left[ {x},{y} \right]},{\left[ {1},{x^{2}} \right]} \right>}} \right>"
)
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_GlobalPolynomialRing_convert():
K1 = QQ.old_poly_ring(x)
K2 = QQ[x]
assert K1.convert(x) == K1.convert(K2.convert(x), K2)
assert K2.convert(x) == K2.convert(K1.convert(x), K1)
K1 = QQ.old_poly_ring(x, y)
K2 = QQ[x]
assert K1.convert(x) == K1.convert(K2.convert(x), K2)
#assert K2.convert(x) == K2.convert(K1.convert(x), K1)
K1 = ZZ.old_poly_ring(x, y)
K2 = QQ[x]
assert K1.convert(x) == K1.convert(K2.convert(x), K2)
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< {x^{2} + 1} \right>}"
assert latex(R.one) == r"{1} + {\left< {x^{2} + 1} \right>}"
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< {x^{2} + 1} \right>}"
assert latex(R.one) == r"{1} + {\left< {x^{2} + 1} \right>}"
def test_globalring():
Qxy = QQ.old_frac_field(x, y)
R = QQ.old_poly_ring(x, y)
X = R.convert(x)
Y = R.convert(y)
assert x in R
assert 1/x not in R
assert 1/(1 + x) not in R
assert Y in R
assert X.ring == R
assert X * (Y**2 + 1) == R.convert(x * (y**2 + 1))
assert X * y == X * Y == R.convert(x * y) == x * Y
assert X + y == X + Y == R.convert(x + y) == x + Y
assert X - y == X - Y == R.convert(x - y) == x - Y
assert X + 1 == R.convert(x + 1)
raises(ExactQuotientFailed, lambda: X/Y)
raises(ExactQuotientFailed, lambda: x/Y)
raises(ExactQuotientFailed, lambda: X/y)
assert X**2 / X == X
assert R.from_GlobalPolynomialRing(ZZ.old_poly_ring(x, y).convert(x), ZZ.old_poly_ring(x, y)) == X
assert R.from_FractionField(Qxy.convert(x), Qxy) == X
assert R.from_FractionField(Qxy.convert(x)/y, Qxy) is None
assert R._sdm_to_vector(R._vector_to_sdm([X, Y], R.order), 2) == [X, Y]
def test_localring():
Qxy = QQ.old_frac_field(x, y)
R = QQ.old_poly_ring(x, y, order="ilex")
X = R.convert(x)
Y = R.convert(y)
assert x in R
assert 1/x not in R
assert 1/(1 + x) in R
assert Y in R
assert X.ring == R
assert X*(Y**2 + 1)/(1 + X) == R.convert(x*(y**2 + 1)/(1 + x))
assert X*y == X*Y
raises(ExactQuotientFailed, lambda: X/Y)
raises(ExactQuotientFailed, lambda: x/Y)
raises(ExactQuotientFailed, lambda: X/y)
assert X + y == X + Y == R.convert(x + y) == x + Y
assert X - y == X - Y == R.convert(x - y) == x - Y
assert X + 1 == R.convert(x + 1)
assert X**2 / X == X
assert R.from_GlobalPolynomialRing(ZZ.old_poly_ring(x, y).convert(x), ZZ.old_poly_ring(x, y)) == X
assert R.from_FractionField(Qxy.convert(x), Qxy) == X
raises(CoercionFailed, lambda: R.from_FractionField(Qxy.convert(x)/y, Qxy))
raises(ExactQuotientFailed, lambda: X/Y)
raises(NotReversible, lambda: X.invert())
assert R._sdm_to_vector(
R._vector_to_sdm([X/(X + 1), Y/(1 + X*Y)], R.order), 2) == \
[X*(1 + X*Y), Y*(1 + X)]
def test_localring():
Qxy = QQ.old_frac_field(x, y)
R = QQ.old_poly_ring(x, y, order="ilex")
X = R.convert(x)
Y = R.convert(y)
assert x in R
assert 1/x not in R
assert 1/(1 + x) in R
assert Y in R
assert X.ring == R
assert X*(Y**2 + 1)/(1 + X) == R.convert(x*(y**2 + 1)/(1 + x))
assert X*y == X*Y
raises(ExactQuotientFailed, lambda: X/Y)
raises(ExactQuotientFailed, lambda: x/Y)
raises(ExactQuotientFailed, lambda: X/y)
assert X + y == X + Y == R.convert(x + y) == x + Y
assert X - y == X - Y == R.convert(x - y) == x - Y
assert X + 1 == R.convert(x + 1)
assert X**2 / X == X
assert R.from_GlobalPolynomialRing(ZZ.old_poly_ring(x, y).convert(x), ZZ.old_poly_ring(x, y)) == X
assert R.from_FractionField(Qxy.convert(x), Qxy) == X
raises(CoercionFailed, lambda: R.from_FractionField(Qxy.convert(x)/y, Qxy))
raises(ExactQuotientFailed, lambda: X/Y)
raises(NotReversible, lambda: X.invert())
assert R._sdm_to_vector(
R._vector_to_sdm([X/(X + 1), Y/(1 + X*Y)], R.order), 2) == \
[X*(1 + X*Y), Y*(1 + X)]
def test_globalring():
Qxy = QQ.old_frac_field(x, y)
R = QQ.old_poly_ring(x, y)
X = R.convert(x)
Y = R.convert(y)
assert x in R
assert 1/x not in R
assert 1/(1 + x) not in R
assert Y in R
assert X.ring == R
assert X * (Y**2 + 1) == R.convert(x * (y**2 + 1))
assert X * y == X * Y == R.convert(x * y) == x * Y
assert X + y == X + Y == R.convert(x + y) == x + Y
assert X - y == X - Y == R.convert(x - y) == x - Y
assert X + 1 == R.convert(x + 1)
raises(ExactQuotientFailed, lambda: X/Y)
raises(ExactQuotientFailed, lambda: x/Y)
raises(ExactQuotientFailed, lambda: X/y)
assert X**2 / X == X
assert R.from_GlobalPolynomialRing(ZZ.old_poly_ring(x, y).convert(x), ZZ.old_poly_ring(x, y)) == X
assert R.from_FractionField(Qxy.convert(x), Qxy) == X
assert R.from_FractionField(Qxy.convert(x)/y, Qxy) is None
assert R._sdm_to_vector(R._vector_to_sdm([X, Y], R.order), 2) == [X, Y]
def test_units():
R = QQ.old_poly_ring(x)
assert R.is_unit(R.convert(1))
assert R.is_unit(R.convert(2))
assert not R.is_unit(R.convert(x))
assert not R.is_unit(R.convert(1 + x))
R = QQ.old_poly_ring(x, order='ilex')
assert R.is_unit(R.convert(1))
assert R.is_unit(R.convert(2))
assert not R.is_unit(R.convert(x))
assert R.is_unit(R.convert(1 + x))
R = ZZ.old_poly_ring(x)
assert R.is_unit(R.convert(1))
assert not R.is_unit(R.convert(2))
assert not R.is_unit(R.convert(x))
assert not R.is_unit(R.convert(1 + x))
def test_units():
R = QQ.old_poly_ring(x)
assert R.is_unit(R.convert(1))
assert R.is_unit(R.convert(2))
assert not R.is_unit(R.convert(x))
assert not R.is_unit(R.convert(1 + x))
R = QQ.old_poly_ring(x, order='ilex')
assert R.is_unit(R.convert(1))
assert R.is_unit(R.convert(2))
assert not R.is_unit(R.convert(x))
assert R.is_unit(R.convert(1 + x))
R = ZZ.old_poly_ring(x)
assert R.is_unit(R.convert(1))
assert not R.is_unit(R.convert(2))
assert not R.is_unit(R.convert(x))
assert not R.is_unit(R.convert(1 + x))
def _create_table(table):
"""
Creates the look-up table. For a similar implementation
see meijerint._create_lookup_table.
"""
def add(formula, annihilator, arg, x0=0, y0=[]):
"""
Adds a formula in the dictionary
"""
table.setdefault(_mytype(formula, x_1), []).append((formula,
HolonomicFunction(annihilator, arg, x0, y0)))
R = QQ.old_poly_ring(x_1)
_, Dx = DifferentialOperators(R, 'Dx')
from sympy import (sin, cos, exp, log, erf, sqrt, pi,
sinh, cosh, sinc, erfc, Si, Ci, Shi, erfi)
# add some basic functions
add(sin(x_1), Dx**2 + 1, x_1, 0, [0, 1])
add(cos(x_1), Dx**2 + 1, x_1, 0, [1, 0])
add(exp(x_1), Dx - 1, x_1, 0, 1)
add(log(x_1), Dx + x_1*Dx**2, x_1, 1, [0, 1])
add(erf(x_1), 2*x_1*Dx + Dx**2, x_1, 0, [0, 2/sqrt(pi)])
add(erfc(x_1), 2*x_1*Dx + Dx**2, x_1, 0, [1, -2/sqrt(pi)])
add(erfi(x_1), -2*x_1*Dx + Dx**2, x_1, 0, [0, 2/sqrt(pi)])
add(sinh(x_1), Dx**2 - 1, x_1, 0, [0, 1])
add(cosh(x_1), Dx**2 - 1, x_1, 0, [1, 0])
add(sinc(x_1), x_1 + 2*Dx + x_1*Dx**2, x_1)
add(Si(x_1), x_1*Dx + 2*Dx**2 + x_1*Dx**3, x_1)
add(Ci(x_1), x_1*Dx + 2*Dx**2 + x_1*Dx**3, x_1)
add(Shi(x_1), -x_1*Dx + 2*Dx**2 + x_1*Dx**3, x_1)
def _convert_poly_rat(func, x, initcond=True):
"""Converts Polynomials and Rationals to Holonomic.
"""
ispoly = func.is_polynomial()
if not ispoly:
israt = func.is_rational_function()
else:
israt = True
if not (ispoly or israt):
return None
R = QQ.old_poly_ring(x)
_, Dx = DifferentialOperators(R, 'Dx')
if ispoly:
# differential equation satisfied by polynomial
sol = func * Dx - func.diff()
sol = _normalize(sol.listofpoly, sol.parent, negative=False)
elif israt:
order = 1
p, q = func.as_numer_denom()
# differential equation satisfied by rational
sol = p * q * Dx + p * q.diff() - q * p.diff()
sol = _normalize(sol.listofpoly, sol.parent, negative=False)
if not initcond:
return HolonomicFunction(sol, x)
x0 = 0
y0 = _find_conditions(func, x, x0, sol.order)
while not y0:
x0 += 1
y0 = _find_conditions(func, x, x0, sol.order)
return HolonomicFunction(sol, x, x0, y0)
def from_hyper(func, x0=0, evalf=False):
"""
Converts Hypergeometric Function to Holonomic.
func is the Hypergeometric Function and x0 be the point at
which initial conditions are required.
Examples
=======
>>> from sympy.holonomic.holonomic import from_hyper, DifferentialOperators
>>> from sympy import symbols, hyper, S
>>> x = symbols('x')
>>> from_hyper(hyper([], [S(3)/2], x**2/4))
HolonomicFunction((-x) + (2)Dx + (x)Dx**2, x), f(1) = sinh(1) , f'(1) = -sinh(1) + cosh(1)
"""
a = func.ap
b = func.bq
z = func.args[2]
x = z.atoms(Symbol).pop()
R, Dx = DifferentialOperators(QQ.old_poly_ring(x), 'Dx')
r1 = 1
for i in range(len(a)):
r1 = r1 * (x * Dx + a[i])
r2 = Dx
for i in range(len(b)):
r2 = r2 * (x * Dx + b[i] - 1)
sol = r1 - r2
simp = hyperexpand(func)
if isinstance(simp, Infinity) or isinstance(simp, NegativeInfinity):
return HolonomicFunction(sol, x).composition(z)
def _find_conditions(simp, x, x0, order, evalf=False):
y0 = []
for i in range(order):
if evalf:
val = simp.subs(x, x0).evalf()
else:
val = simp.subs(x, x0)
if isinstance(val, Infinity) or isinstance(val, NaN):
return None
y0.append(val)
simp = simp.diff()
return y0
if not isinstance(simp, hyper):
y0 = _find_conditions(simp, x, x0, sol.order)
while not y0:
x0 += 1
y0 = _find_conditions(simp, x, x0, sol.order)
return HolonomicFunction(sol, x, x0, y0).composition(z)
if isinstance(simp, hyper):
x0 = 1
y0 = _find_conditions(simp, x, x0, sol.order, evalf)
while not y0:
x0 += 1
y0 = _find_conditions(simp, x, x0, sol.order, evalf)
return HolonomicFunction(sol, x, x0, y0).composition(z)
return HolonomicFunction(sol, x).composition(z)
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_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 from_hyper(func, x0=0, evalf=False):
"""
Converts Hypergeometric Function to Holonomic.
func is the Hypergeometric Function and x0 be the point at
which initial conditions are required.
Examples
=======
>>> from sympy.holonomic.holonomic import from_hyper, DifferentialOperators
>>> from sympy import symbols, hyper, S
>>> x = symbols('x')
>>> from_hyper(hyper([], [S(3)/2], x**2/4))
HolonomicFunction((-x) + (2)Dx + (x)Dx**2, x), f(1) = sinh(1), f'(1) = -sinh(1) + cosh(1)
"""
a = func.ap
b = func.bq
z = func.args[2]
x = z.atoms(Symbol).pop()
R, Dx = DifferentialOperators(QQ.old_poly_ring(x), 'Dx')
# generalized hypergeometric differential equation
r1 = 1
for i in range(len(a)):
r1 = r1 * (x * Dx + a[i])
r2 = Dx
for i in range(len(b)):
r2 = r2 * (x * Dx + b[i] - 1)
sol = r1 - r2
simp = hyperexpand(func)
if isinstance(simp, Infinity) or isinstance(simp, NegativeInfinity):
return HolonomicFunction(sol, x).composition(z)
def _find_conditions(simp, x, x0, order, evalf=False):
y0 = []
for i in range(order):
if evalf:
val = simp.subs(x, x0).evalf()
else:
val = simp.subs(x, x0)
# return None if it is Infinite or NaN
if (val.is_finite is not None and not val.is_finite) or isinstance(val, NaN):
return None
y0.append(val)
simp = simp.diff()
return y0
# if the function is known symbolically
if not isinstance(simp, hyper):
y0 = _find_conditions(simp, x, x0, sol.order)
while not y0:
# if values don't exist at 0, then try to find initial
# conditions at 1. If it doesn't exist at 1 too then
# try 2 and so on.
x0 += 1
y0 = _find_conditions(simp, x, x0, sol.order)
return HolonomicFunction(sol, x).composition(z, x0, y0)
if isinstance(simp, hyper):
x0 = 1
# use evalf if the function can't be simpified
y0 = _find_conditions(simp, x, x0, sol.order, evalf)
while not y0:
x0 += 1
y0 = _find_conditions(simp, x, x0, sol.order, evalf)
return HolonomicFunction(sol, x).composition(z, x0, y0)
return HolonomicFunction(sol, x).composition(z)
def test_build_order():
R = QQ.old_poly_ring(x, y, order=(("lex", x), ("ilex", y)))
assert R.order((1, 5)) == ((1,), (-5,))
def from_meijerg(func, x0=0, evalf=False):
"""
Converts a Meijer G-function to Holonomic.
func is the Hypergeometric Function and x0 be the point at
which initial conditions are required.
Examples
=======
>>> from sympy.holonomic.holonomic import from_meijerg, DifferentialOperators
>>> from sympy import symbols, meijerg, S
>>> x = symbols('x')
>>> from_meijerg(meijerg(([], []), ([S(1)/2], [0]), x**2/4))
HolonomicFunction((1) + (1)Dx**2, x), f(0) = 0, f'(0) = 1/sqrt(pi)
"""
a = func.ap
b = func.bq
n = len(func.an)
m = len(func.bm)
p = len(a)
z = func.args[2]
x = z.atoms(Symbol).pop()
R, Dx = DifferentialOperators(QQ.old_poly_ring(x), 'Dx')
# compute the differential equation satisfied by the
# Meijer G-function.
mnp = (-1)**(m + n - p)
r1 = x * mnp
for i in range(len(a)):
r1 *= x * Dx + 1 - a[i]
r2 = 1
for i in range(len(b)):
r2 *= x * Dx - b[i]
sol = r1 - r2
simp = hyperexpand(func)
if isinstance(simp, Infinity) or isinstance(simp, NegativeInfinity):
return HolonomicFunction(sol, x).composition(z)
def _find_conditions(simp, x, x0, order, evalf=False):
y0 = []
for i in range(order):
if evalf:
val = simp.subs(x, x0).evalf()
else:
val = simp.subs(x, x0)
if (val.is_finite is not None and not val.is_finite) or isinstance(val, NaN):
return None
y0.append(val)
simp = simp.diff()
return y0
# computing initial conditions
if not isinstance(simp, meijerg):
y0 = _find_conditions(simp, x, x0, sol.order)
while not y0:
x0 += 1
y0 = _find_conditions(simp, x, x0, sol.order)
return HolonomicFunction(sol, x).composition(z, x0, y0)
if isinstance(simp, meijerg):
x0 = 1
y0 = _find_conditions(simp, x, x0, sol.order, evalf)
while not y0:
x0 += 1
y0 = _find_conditions(simp, x, x0, sol.order, evalf)
return HolonomicFunction(sol, x).composition(z, x0, y0)
return HolonomicFunction(sol, x).composition(z)
def test_build_order():
R = QQ.old_poly_ring(x, y, order=(("lex", x), ("ilex", y)))
assert R.order((1, 5)) == ((1,), (-5,))
