def test_requires_partial():
x, y, t, nu = symbols('x y t nu')
n = symbols('n', integer=True)
f = x * y
assert requires_partial(Derivative(f, x)) is True
assert requires_partial(Derivative(f, y)) is True
# integrating out one of the variables
assert requires_partial(
Derivative(Integral(exp(-x * y),
(x, 0, oo)), y, evaluate=False)) is False
# bessel function with smooth parameter
f = besselj(nu, x)
assert requires_partial(Derivative(f, x)) is True
assert requires_partial(Derivative(f, nu)) is True
# bessel function with integer parameter
f = besselj(n, x)
assert requires_partial(Derivative(f, x)) is False
# this is not really valid (differentiating with respect to an integer)
# but there's no reason to use the partial derivative symbol there. make
# sure we don't throw an exception here, though
assert requires_partial(Derivative(f, n)) is False
# bell polynomial
f = bell(n, x)
assert requires_partial(Derivative(f, x)) is False
# again, invalid
assert requires_partial(Derivative(f, n)) is False
# legendre polynomial
f = legendre(0, x)
assert requires_partial(Derivative(f, x)) is False
f = legendre(n, x)
assert requires_partial(Derivative(f, x)) is False
# again, invalid
assert requires_partial(Derivative(f, n)) is False
f = x**n
assert requires_partial(Derivative(f, x)) is False
assert requires_partial(
Derivative(
Integral((x * y)**n * exp(-x * y),
(x, 0, oo)), y, evaluate=False)) is False
# parametric equation
f = (exp(t), cos(t))
g = sum(f)
assert requires_partial(Derivative(g, t)) is False
# function of unspecified variables
f = symbols('f', cls=Function)
assert requires_partial(Derivative(f, x)) is False
assert requires_partial(Derivative(f, x, y)) is True
def test_jacobi():
assert jacobi(0, a, b, x) == 1
assert jacobi(1, a, b, x) == a / 2 - b / 2 + x * (a / 2 + b / 2 + 1)
assert (jacobi(2, a, b, x) == a**2 / 8 - a * b / 4 - a / 8 + b**2 / 8 -
b / 8 + x**2 * (a**2 / 8 + a * b / 4 + 7 * a / 8 + b**2 / 8 +
7 * b / 8 + Rational(3, 2)) + x *
(a**2 / 4 + 3 * a / 4 - b**2 / 4 - 3 * b / 4) - S.Half)
assert jacobi(n, a, a, x) == RisingFactorial(a + 1, n) * gegenbauer(
n, a + Rational(1, 2), x) / RisingFactorial(2 * a + 1, n)
assert jacobi(n, a, -a,
x) == ((-1)**a * (-x + 1)**(-a / 2) * (x + 1)**(a / 2) *
assoc_legendre(n, a, x) * factorial(-a + n) *
gamma(a + n + 1) / (factorial(a + n) * gamma(n + 1)))
assert jacobi(n, -b, b, x) == ((-x + 1)**(b / 2) * (x + 1)**(-b / 2) *
assoc_legendre(n, b, x) *
gamma(-b + n + 1) / gamma(n + 1))
assert jacobi(n, 0, 0, x) == legendre(n, x)
assert jacobi(n, S.Half, S.Half, x) == RisingFactorial(Rational(
3, 2), n) * chebyshevu(n, x) / factorial(n + 1)
assert jacobi(n, -S.Half, -S.Half, x) == RisingFactorial(
Rational(1, 2), n) * chebyshevt(n, x) / factorial(n)
X = jacobi(n, a, b, x)
assert isinstance(X, jacobi)
assert jacobi(n, a, b, -x) == (-1)**n * jacobi(n, b, a, x)
assert jacobi(n, a, b, 0) == 2**(-n) * gamma(a + n + 1) * hyper(
(-b - n, -n), (a + 1, ), -1) / (factorial(n) * gamma(a + 1))
assert jacobi(n, a, b, 1) == RisingFactorial(a + 1, n) / factorial(n)
m = Symbol("m", positive=True)
assert jacobi(m, a, b, oo) == oo * RisingFactorial(a + b + m + 1, m)
assert conjugate(jacobi(m, a, b, x)) == \
jacobi(m, conjugate(a), conjugate(b), conjugate(x))
assert diff(jacobi(n, a, b, x), n) == Derivative(jacobi(n, a, b, x), n)
assert diff(jacobi(n, a, b, x), x) == \
(a/2 + b/2 + n/2 + Rational(1, 2))*jacobi(n - 1, a + 1, b + 1, x)
# XXX see issue sympy/sympy#5539
assert str(jacobi(n, a, b, x).diff(a)) == \
("Sum((jacobi(n, a, b, x) + (a + b + 2*_k + 1)*RisingFactorial(b + "
"_k + 1, n - _k)*jacobi(_k, a, b, x)/((n - _k)*RisingFactorial(a + "
"b + _k + 1, n - _k)))/(a + b + n + _k + 1), (_k, 0, n - 1))")
assert str(jacobi(n, a, b, x).diff(b)) == \
("Sum(((-1)**(n - _k)*(a + b + 2*_k + 1)*RisingFactorial(a + "
"_k + 1, n - _k)*jacobi(_k, a, b, x)/((n - _k)*RisingFactorial(a + "
"b + _k + 1, n - _k)) + jacobi(n, a, b, x))/(a + b + n + "
"_k + 1), (_k, 0, n - 1))")
assert jacobi_normalized(n, a, b, x) == \
(jacobi(n, a, b, x)/sqrt(2**(a + b + 1)*gamma(a + n + 1)*gamma(b + n + 1)
/ ((a + b + 2*n + 1)*factorial(n)*gamma(a + b + n + 1))))
pytest.raises(ValueError, lambda: jacobi(-2.1, a, b, x))
pytest.raises(ValueError,
lambda: jacobi(Dummy(positive=True, integer=True), 1, 2, oo))
pytest.raises(ArgumentIndexError, lambda: jacobi(n, a, b, x).fdiff(5))
def test_jacobi():
assert jacobi(0, a, b, x) == 1
assert jacobi(1, a, b, x) == a/2 - b/2 + x*(a/2 + b/2 + 1)
assert (jacobi(2, a, b, x) == a**2/8 - a*b/4 - a/8 + b**2/8 - b/8 +
x**2*(a**2/8 + a*b/4 + 7*a/8 + b**2/8 + 7*b/8 + Rational(3, 2)) +
x*(a**2/4 + 3*a/4 - b**2/4 - 3*b/4) - Rational(1, 2))
assert jacobi(n, a, a, x) == RisingFactorial(
a + 1, n)*gegenbauer(n, a + Rational(1, 2), x)/RisingFactorial(2*a + 1, n)
assert jacobi(n, a, -a, x) == ((-1)**a*(-x + 1)**(-a/2)*(x + 1)**(a/2)*assoc_legendre(n, a, x) *
factorial(-a + n)*gamma(a + n + 1)/(factorial(a + n)*gamma(n + 1)))
assert jacobi(n, -b, b, x) == ((-x + 1)**(b/2)*(x + 1)**(-b/2)*assoc_legendre(n, b, x) *
gamma(-b + n + 1)/gamma(n + 1))
assert jacobi(n, 0, 0, x) == legendre(n, x)
assert jacobi(n, Rational(1, 2), Rational(1, 2), x) == RisingFactorial(
Rational(3, 2), n)*chebyshevu(n, x)/factorial(n + 1)
assert jacobi(n, Rational(-1, 2), Rational(-1, 2), x) == RisingFactorial(
Rational(1, 2), n)*chebyshevt(n, x)/factorial(n)
X = jacobi(n, a, b, x)
assert isinstance(X, jacobi)
assert jacobi(n, a, b, -x) == (-1)**n*jacobi(n, b, a, x)
assert jacobi(n, a, b, 0) == 2**(-n)*gamma(a + n + 1)*hyper(
(-b - n, -n), (a + 1,), -1)/(factorial(n)*gamma(a + 1))
assert jacobi(n, a, b, 1) == RisingFactorial(a + 1, n)/factorial(n)
m = Symbol("m", positive=True)
assert jacobi(m, a, b, oo) == oo*RisingFactorial(a + b + m + 1, m)
assert jacobi(n, a, b, oo) == jacobi(n, a, b, oo, evaluate=False)
assert conjugate(jacobi(m, a, b, x)) == \
jacobi(m, conjugate(a), conjugate(b), conjugate(x))
assert diff(jacobi(n, a, b, x), n) == Derivative(jacobi(n, a, b, x), n)
assert diff(jacobi(n, a, b, x), x) == \
(a/2 + b/2 + n/2 + Rational(1, 2))*jacobi(n - 1, a + 1, b + 1, x)
# XXX see issue sympy/sympy#5539
assert str(jacobi(n, a, b, x).diff(a)) == \
("Sum((jacobi(n, a, b, x) + (a + b + 2*_k + 1)*RisingFactorial(b + "
"_k + 1, n - _k)*jacobi(_k, a, b, x)/((n - _k)*RisingFactorial(a + "
"b + _k + 1, n - _k)))/(a + b + n + _k + 1), (_k, 0, n - 1))")
assert str(jacobi(n, a, b, x).diff(b)) == \
("Sum(((-1)**(n - _k)*(a + b + 2*_k + 1)*RisingFactorial(a + "
"_k + 1, n - _k)*jacobi(_k, a, b, x)/((n - _k)*RisingFactorial(a + "
"b + _k + 1, n - _k)) + jacobi(n, a, b, x))/(a + b + n + "
"_k + 1), (_k, 0, n - 1))")
assert jacobi_normalized(n, a, b, x) == \
(jacobi(n, a, b, x)/sqrt(2**(a + b + 1)*gamma(a + n + 1)*gamma(b + n + 1)
/ ((a + b + 2*n + 1)*factorial(n)*gamma(a + b + n + 1))))
pytest.raises(ValueError, lambda: jacobi(-2.1, a, b, x))
pytest.raises(ValueError, lambda: jacobi(Dummy(positive=True, integer=True), 1, 2, oo))
pytest.raises(ArgumentIndexError, lambda: jacobi(n, a, b, x).fdiff(5))
def test_assoc_legendre():
Plm = assoc_legendre
Q = sqrt(1 - x**2)
assert Plm(0, 0, x) == 1
assert Plm(1, 0, x) == x
assert Plm(1, 1, x) == -Q
assert Plm(2, 0, x) == (3 * x**2 - 1) / 2
assert Plm(2, 1, x) == -3 * x * Q
assert Plm(2, 2, x) == 3 * Q**2
assert Plm(3, 0, x) == (5 * x**3 - 3 * x) / 2
assert Plm(3, 1,
x).expand() == ((3 * (1 - 5 * x**2) / 2).expand() * Q).expand()
assert Plm(3, 2, x) == 15 * x * Q**2
assert Plm(3, 3, x) == -15 * Q**3
# negative m
assert Plm(1, -1, x) == -Plm(1, 1, x) / 2
assert Plm(2, -2, x) == Plm(2, 2, x) / 24
assert Plm(2, -1, x) == -Plm(2, 1, x) / 6
assert Plm(3, -3, x) == -Plm(3, 3, x) / 720
assert Plm(3, -2, x) == Plm(3, 2, x) / 120
assert Plm(3, -1, x) == -Plm(3, 1, x) / 12
X = Plm(n, m, x)
assert isinstance(X, assoc_legendre)
assert Plm(n, 0, x) == legendre(n, x)
assert Plm(n, m, 0) == 2**m * sqrt(pi) / (gamma(
(1 - m - n) / 2) * gamma(1 - (m - n) / 2))
pytest.raises(ValueError, lambda: Plm(-1, 0, x))
pytest.raises(ValueError, lambda: Plm(0, 1, x))
pytest.raises(ValueError, lambda: Plm(-1, 2, x))
assert conjugate(assoc_legendre(n, m, x)) == \
assoc_legendre(n, conjugate(m), conjugate(x))
assert assoc_legendre(n, m, x).diff(x) == \
(n*x*assoc_legendre(n, m, x) -
(m + n)*assoc_legendre(n - 1, m, x))/(x**2 - 1)
pytest.raises(ArgumentIndexError, lambda: assoc_legendre(n, m, x).fdiff(1))
assert (str(assoc_laguerre(
n, m,
x).diff(m)) == 'Sum(assoc_laguerre(_k, m, x)/(-m + n), (_k, 0, n - 1))'
)
def main():
print(__doc__)
x = symbols('x')
# a numpy array we can apply the ufuncs to
grid = np.linspace(-1, 1, 1000)
# set mpmath precision to 20 significant numbers for verification
mpmath.mp.dps = 20
print("Compiling legendre ufuncs and checking results:")
# Let's also plot the ufunc's we generate
for n in range(6):
# Setup the Diofant expression to ufuncify
expr = legendre(n, x)
print("The polynomial of degree %i is" % n)
pprint(expr)
# This is where the magic happens:
binary_poly = ufuncify(x, expr)
# It's now ready for use with numpy arrays
polyvector = binary_poly(grid)
# let's check the values against mpmath's legendre function
maxdiff = 0
for j in range(len(grid)):
precise_val = mpmath.legendre(n, grid[j])
diff = abs(polyvector[j] - precise_val)
if diff > maxdiff:
maxdiff = diff
print("The largest error in applied ufunc was %e" % maxdiff)
assert maxdiff < 1e-14
# We can also attach the autowrapped legendre polynomial to a diofant
# function and plot values as they are calculated by the binary function
plot1 = plt.pyplot.plot(grid, polyvector, hold=True)
print(
"Here's a plot with values calculated by the wrapped binary functions")
plt.pyplot.show()
def test_assoc_legendre():
Plm = assoc_legendre
Q = sqrt(1 - x**2)
assert Plm(0, 0, x) == 1
assert Plm(1, 0, x) == x
assert Plm(1, 1, x) == -Q
assert Plm(2, 0, x) == (3*x**2 - 1)/2
assert Plm(2, 1, x) == -3*x*Q
assert Plm(2, 2, x) == 3*Q**2
assert Plm(3, 0, x) == (5*x**3 - 3*x)/2
assert Plm(3, 1, x).expand() == (( 3*(1 - 5*x**2)/2 ).expand() * Q).expand()
assert Plm(3, 2, x) == 15*x * Q**2
assert Plm(3, 3, x) == -15 * Q**3
# negative m
assert Plm(1, -1, x) == -Plm(1, 1, x)/2
assert Plm(2, -2, x) == Plm(2, 2, x)/24
assert Plm(2, -1, x) == -Plm(2, 1, x)/6
assert Plm(3, -3, x) == -Plm(3, 3, x)/720
assert Plm(3, -2, x) == Plm(3, 2, x)/120
assert Plm(3, -1, x) == -Plm(3, 1, x)/12
X = Plm(n, m, x)
assert isinstance(X, assoc_legendre)
assert Plm(n, 0, x) == legendre(n, x)
assert Plm(n, m, 0) == 2**m*sqrt(pi)/(gamma((1 - m - n)/2)*gamma(1 - (m - n)/2))
pytest.raises(ValueError, lambda: Plm(-1, 0, x))
pytest.raises(ValueError, lambda: Plm(0, 1, x))
pytest.raises(ValueError, lambda: Plm(-1, 2, x))
assert conjugate(assoc_legendre(n, m, x)) == \
assoc_legendre(n, conjugate(m), conjugate(x))
assert assoc_legendre(n, m, x).diff(x) == \
(n*x*assoc_legendre(n, m, x) -
(m + n)*assoc_legendre(n - 1, m, x))/(x**2 - 1)
pytest.raises(ArgumentIndexError, lambda: assoc_legendre(n, m, x).fdiff(1))
assert (str(assoc_laguerre(n, m, x).diff(m)) ==
'Sum(assoc_laguerre(_k, m, x)/(-m + n), (_k, 0, n - 1))')
def test_gegenbauer():
assert gegenbauer(0, a, x) == 1
assert gegenbauer(1, a, x) == 2 * a * x
assert gegenbauer(2, a, x) == -a + x**2 * (2 * a**2 + 2 * a)
assert gegenbauer(3, a, x) == \
x**3*(4*a**3/3 + 4*a**2 + 8*a/3) + x*(-2*a**2 - 2*a)
assert gegenbauer(-1, a, x) == 0
assert gegenbauer(n, Rational(1, 2), x) == legendre(n, x)
assert gegenbauer(n, 1, x) == chebyshevu(n, x)
assert gegenbauer(n, -1, x) == 0
assert gegenbauer(n, -2, -1) == gegenbauer(n, -2, -1, evaluate=False)
X = gegenbauer(n, a, x)
assert isinstance(X, gegenbauer)
assert gegenbauer(n, a, -x) == (-1)**n * gegenbauer(n, a, x)
assert gegenbauer(n, a, 0) == 2**n*sqrt(pi) * \
gamma(a + n/2)/(gamma(a)*gamma(-n/2 + Rational(1, 2))*gamma(n + 1))
assert gegenbauer(n, a,
1) == gamma(2 * a + n) / (gamma(2 * a) * gamma(n + 1))
assert gegenbauer(n, Rational(3, 4), -1) == zoo
m = Symbol("m", positive=True)
assert gegenbauer(m, a, oo) == oo * RisingFactorial(a, m)
assert gegenbauer(n, a, oo) == gegenbauer(n, a, oo, evaluate=False)
assert conjugate(gegenbauer(n,
a, x)) == gegenbauer(n, conjugate(a),
conjugate(x))
assert diff(gegenbauer(n, a, x), n) == Derivative(gegenbauer(n, a, x), n)
assert diff(gegenbauer(n, a, x), x) == 2 * a * gegenbauer(n - 1, a + 1, x)
pytest.raises(ArgumentIndexError, lambda: gegenbauer(n, a, x).fdiff(4))
# XXX see issue sympy/sympy#5539
assert str(gegenbauer(n, a, x).diff(a)) == \
("Sum((2*(-1)**(n - _k) + 2)*(a + _k)*gegenbauer(_k, a, x)/((n - "
"_k)*(2*a + n + _k)) + (2/(2*a + n + _k) + (2*_k + 2)/((2*a + "
"_k)*(2*a + 2*_k + 1)))*gegenbauer(n, a, x), (_k, 0, n - 1))")
def test_gegenbauer():
assert gegenbauer(0, a, x) == 1
assert gegenbauer(1, a, x) == 2*a*x
assert gegenbauer(2, a, x) == -a + x**2*(2*a**2 + 2*a)
assert gegenbauer(3, a, x) == \
x**3*(4*a**3/3 + 4*a**2 + 8*a/3) + x*(-2*a**2 - 2*a)
assert gegenbauer(-1, a, x) == 0
assert gegenbauer(n, Rational(1, 2), x) == legendre(n, x)
assert gegenbauer(n, 1, x) == chebyshevu(n, x)
assert gegenbauer(n, -1, x) == 0
assert gegenbauer(n, -2, -1) == gegenbauer(n, -2, -1, evaluate=False)
X = gegenbauer(n, a, x)
assert isinstance(X, gegenbauer)
assert gegenbauer(n, a, -x) == (-1)**n*gegenbauer(n, a, x)
assert gegenbauer(n, a, 0) == 2**n*sqrt(pi) * \
gamma(a + n/2)/(gamma(a)*gamma(-n/2 + Rational(1, 2))*gamma(n + 1))
assert gegenbauer(n, a, 1) == gamma(2*a + n)/(gamma(2*a)*gamma(n + 1))
assert gegenbauer(n, Rational(3, 4), -1) == zoo
m = Symbol("m", positive=True)
assert gegenbauer(m, a, oo) == oo*RisingFactorial(a, m)
assert gegenbauer(n, a, oo) == gegenbauer(n, a, oo, evaluate=False)
assert conjugate(gegenbauer(n, a, x)) == gegenbauer(n, conjugate(a), conjugate(x))
assert diff(gegenbauer(n, a, x), n) == Derivative(gegenbauer(n, a, x), n)
assert diff(gegenbauer(n, a, x), x) == 2*a*gegenbauer(n - 1, a + 1, x)
pytest.raises(ArgumentIndexError, lambda: gegenbauer(n, a, x).fdiff(4))
# XXX see issue sympy/sympy#5539
assert str(gegenbauer(n, a, x).diff(a)) == \
("Sum((2*(-1)**(n - _k) + 2)*(a + _k)*gegenbauer(_k, a, x)/((n - "
"_k)*(2*a + n + _k)) + (2/(2*a + n + _k) + (2*_k + 2)/((2*a + "
"_k)*(2*a + 2*_k + 1)))*gegenbauer(n, a, x), (_k, 0, n - 1))")
def test_legendre():
pytest.raises(ValueError, lambda: legendre(-1, x))
assert legendre(0, x) == 1
assert legendre(1, x) == x
assert legendre(2, x) == ((3 * x**2 - 1) / 2).expand()
assert legendre(3, x) == ((5 * x**3 - 3 * x) / 2).expand()
assert legendre(4, x) == ((35 * x**4 - 30 * x**2 + 3) / 8).expand()
assert legendre(5, x) == ((63 * x**5 - 70 * x**3 + 15 * x) / 8).expand()
assert legendre(6, x) == ((231 * x**6 - 315 * x**4 + 105 * x**2 - 5) /
16).expand()
assert legendre(10, -1) == 1
assert legendre(11, -1) == -1
assert legendre(10, 1) == 1
assert legendre(11, 1) == 1
assert legendre(10, 0) != 0
assert legendre(11, 0) == 0
assert roots(legendre(4, x), x) == {
sqrt(Rational(3, 7) - Rational(2, 35) * sqrt(30)): 1,
-sqrt(Rational(3, 7) - Rational(2, 35) * sqrt(30)): 1,
sqrt(Rational(3, 7) + Rational(2, 35) * sqrt(30)): 1,
-sqrt(Rational(3, 7) + Rational(2, 35) * sqrt(30)): 1,
}
X = legendre(n, x)
assert isinstance(X, legendre)
assert legendre(-n, x) == legendre(n - 1, x)
assert legendre(n, -x) == (-1)**n * legendre(n, x)
assert legendre(n,
0) == sqrt(pi) / (gamma(S.Half - n / 2) * gamma(1 + n / 2))
assert legendre(n, 1) == 1
assert legendre(n, oo) == oo
assert conjugate(legendre(n, x)) == legendre(n, conjugate(x))
assert diff(legendre(n, x), x) == \
n*(x*legendre(n, x) - legendre(n - 1, x))/(x**2 - 1)
assert diff(legendre(n, x), n) == Derivative(legendre(n, x), n)
def test_legendre():
pytest.raises(ValueError, lambda: legendre(-1, x))
assert legendre(0, x) == 1
assert legendre(1, x) == x
assert legendre(2, x) == ((3*x**2 - 1)/2).expand()
assert legendre(3, x) == ((5*x**3 - 3*x)/2).expand()
assert legendre(4, x) == ((35*x**4 - 30*x**2 + 3)/8).expand()
assert legendre(5, x) == ((63*x**5 - 70*x**3 + 15*x)/8).expand()
assert legendre(6, x) == ((231*x**6 - 315*x**4 + 105*x**2 - 5)/16).expand()
assert legendre(10, -1) == 1
assert legendre(11, -1) == -1
assert legendre(10, 1) == 1
assert legendre(11, 1) == 1
assert legendre(10, 0) != 0
assert legendre(11, 0) == 0
assert roots(legendre(4, x), x) == {
sqrt(Rational(3, 7) - Rational(2, 35)*sqrt(30)): 1,
-sqrt(Rational(3, 7) - Rational(2, 35)*sqrt(30)): 1,
sqrt(Rational(3, 7) + Rational(2, 35)*sqrt(30)): 1,
-sqrt(Rational(3, 7) + Rational(2, 35)*sqrt(30)): 1,
}
X = legendre(n, x)
assert isinstance(X, legendre)
assert legendre(-n, x) == legendre(n - 1, x)
assert legendre(n, -x) == (-1)**n*legendre(n, x)
assert legendre(n, 0) == sqrt(pi)/(gamma(Rational(1, 2) - n/2)*gamma(1 + n/2))
assert legendre(n, 1) == 1
assert legendre(n, oo) == oo
assert conjugate(legendre(n, x)) == legendre(n, conjugate(x))
assert diff(legendre(n, x), x) == \
n*(x*legendre(n, x) - legendre(n - 1, x))/(x**2 - 1)
assert diff(legendre(n, x), n) == Derivative(legendre(n, x), n)
