def test_euler_sineg():
psi = Function('psi')
t = Symbol('t')
x = Symbol('x')
L = diff(psi(t, x), t)**2/2 - diff(psi(t, x), x)**2/2 + cos(psi(t, x))
assert euler(L, psi(t, x), [t, x]) == [Eq(-sin(psi(t, x)) -
diff(psi(t, x), t, t) +
diff(psi(t, x), x, x))]
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_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_euler_henonheiles():
x = Function('x')
y = Function('y')
t = Symbol('t')
L = sum(diff(z(t), t)**2/2 - z(t)**2/2 for z in [x, y])
L += -x(t)**2*y(t) + y(t)**3/3
assert euler(L, [x(t), y(t)], t) == [Eq(-2*x(t)*y(t) - x(t) -
diff(x(t), t, t)),
Eq(-x(t)**2 + y(t)**2 -
y(t) - diff(y(t), t, t))]
def test_unhandled():
class MyExpr(Expr):
def _eval_derivative(self, s):
if not s.name.startswith('xi'):
return self
else:
return
expr = MyExpr(x, y, z)
assert diff(expr, x, y, f(x), z) == Derivative(expr, f(x), z)
assert diff(expr, f(x), x) == Derivative(expr, f(x), x)
def test_pde_separate():
f, X, Y = map(Function, 'fXY')
pytest.raises(ValueError,
lambda: pde_separate(f(x, y).diff(x), f(x, y),
[X(x), Y(y)], strategy='spam'))
eq = diff(f(x, y), x) - exp(f(x, y))*diff(f(x, y), y)
assert pde_separate(eq, f(x, y),
[X(x), Y(y)],
strategy='add') == [exp(-X(x))*diff(X(x), x),
exp(Y(y))*diff(Y(y), y)]
def test_chebyshev():
assert chebyshevt(0, x) == 1
assert chebyshevt(1, x) == x
assert chebyshevt(2, x) == 2*x**2 - 1
assert chebyshevt(3, x) == 4*x**3 - 3*x
assert chebyshevt(-2, x) == 2*x**2 - 1
for n in range(1, 4):
for k in range(n):
z = chebyshevt_root(n, k)
assert chebyshevt(n, z) == 0
pytest.raises(ValueError, lambda: chebyshevt_root(n, n))
for n in range(1, 4):
for k in range(n):
z = chebyshevu_root(n, k)
assert chebyshevu(n, z) == 0
pytest.raises(ValueError, lambda: chebyshevu_root(n, n))
n = Symbol("n")
X = chebyshevt(n, x)
assert isinstance(X, chebyshevt)
assert chebyshevt(n, -x) == (-1)**n*chebyshevt(n, x)
assert chebyshevt(-n, x) == chebyshevt(n, x)
assert chebyshevt(n, oo) == oo
assert chebyshevt(n, 0) == cos(pi*n/2)
assert chebyshevt(n, 1) == 1
assert conjugate(chebyshevt(n, x)) == chebyshevt(n, conjugate(x))
assert diff(chebyshevt(n, x), x) == n*chebyshevu(n - 1, x)
pytest.raises(ArgumentIndexError, lambda: chebyshevt(n, x).fdiff(1))
X = chebyshevu(n, x)
assert isinstance(X, chebyshevu)
assert chebyshevu(n, -x) == (-1)**n*chebyshevu(n, x)
assert chebyshevu(-n, x) == -chebyshevu(n - 2, x)
assert chebyshevu(n, oo) == oo
assert chebyshevu(n, 0) == cos(pi*n/2)
assert chebyshevu(n, 1) == n + 1
assert chebyshevu(-1, x) == 0
assert chebyshevu(-2, x) == -1
assert conjugate(chebyshevu(n, x)) == chebyshevu(n, conjugate(x))
assert diff(chebyshevu(n, x), x) == \
(-x*chebyshevu(n, x) + (n + 1)*chebyshevt(n + 1, x))/(x**2 - 1)
pytest.raises(ArgumentIndexError, lambda: chebyshevu(n, x).fdiff(1))
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_beta():
assert isinstance(beta(x, y), beta)
assert expand_func(beta(x, y)) == gamma(x)*gamma(y)/gamma(x + y)
assert expand_func(beta(x, y) - beta(y, x)) == 0 # Symmetric
assert expand_func(beta(x, y)) == expand_func(beta(x, y + 1) +
beta(x + 1, y)).simplify()
assert diff(beta(x, y), x) == beta(x, y)*(digamma(x) - digamma(x + y))
assert diff(beta(x, y), y) == beta(x, y)*(digamma(y) - digamma(x + y))
pytest.raises(ArgumentIndexError, lambda: beta(x, y).fdiff(3))
assert conjugate(beta(x, y)) == beta(conjugate(x), conjugate(y))
def test_fcode_Piecewise():
expr = Piecewise((x, x < 1), (x**2, True))
# Check that inline conditional (merge) fails if standard isn't 95+
pytest.raises(NotImplementedError, lambda: fcode(expr))
code = fcode(expr, standard=95)
expected = " merge(x, x**2, x < 1)"
assert code == expected
assert fcode(Piecewise((x, x < 1), (x**2, True)), assign_to="var") == (
" if (x < 1) then\n"
" var = x\n"
" else\n"
" var = x**2\n"
" end if"
)
a = cos(x)/x
b = sin(x)/x
for i in range(10):
a = diff(a, x)
b = diff(b, x)
expected = (
" if (x < 0) then\n"
" weird_name = -cos(x)/x + 10*sin(x)/x**2 + 90*cos(x)/x**3 - 720*\n"
" @ sin(x)/x**4 - 5040*cos(x)/x**5 + 30240*sin(x)/x**6 + 151200*cos(x\n"
" @ )/x**7 - 604800*sin(x)/x**8 - 1814400*cos(x)/x**9 + 3628800*sin(x\n"
" @ )/x**10 + 3628800*cos(x)/x**11\n"
" else\n"
" weird_name = -sin(x)/x - 10*cos(x)/x**2 + 90*sin(x)/x**3 + 720*\n"
" @ cos(x)/x**4 - 5040*sin(x)/x**5 - 30240*cos(x)/x**6 + 151200*sin(x\n"
" @ )/x**7 + 604800*cos(x)/x**8 - 1814400*sin(x)/x**9 - 3628800*cos(x\n"
" @ )/x**10 + 3628800*sin(x)/x**11\n"
" end if"
)
code = fcode(Piecewise((a, x < 0), (b, True)), assign_to="weird_name")
assert code == expected
code = fcode(Piecewise((x, x < 1), (x**2, x > 1), (sin(x), True)), standard=95)
expected = " merge(x, merge(x**2, sin(x), x > 1), x < 1)"
assert code == expected
# Check that Piecewise without a True (default) condition error
expr = Piecewise((x, x < 1), (x**2, x > 1), (sin(x), x > 0))
pytest.raises(ValueError, lambda: fcode(expr))
assert (fcode(Piecewise((0, x < -1), (1, And(x >= -1, x < 0)),
(-1, True)), assign_to="var") ==
' if (x < -1) then\n'
' var = 0\n'
' else if (x >= -1 .and. x < 0) then\n'
' var = 1\n'
' else\n'
' var = -1\n'
' end if')
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_collect_D():
D = Derivative
f = Function('f')
fx = D(f(x), x)
fxx = D(f(x), x, x)
assert collect(a*fx + b*fx, fx) == (a + b)*fx
assert collect(a*D(fx, x) + b*D(fx, x), fx) == (a + b)*D(fx, x)
assert collect(a*fxx + b*fxx, fx) == (a + b)*D(fx, x)
# issue sympy/sympy#4784
assert collect(5*f(x) + 3*fx, fx) == 5*f(x) + 3*fx
assert collect(f(x) + f(x)*diff(f(x), x) + x*diff(f(x), x)*f(x), f(x).diff(x), exact=True) == \
(x*f(x) + f(x))*D(f(x), x) + f(x)
assert collect(1/f(x) + 1/f(x)*diff(f(x), x) + x*diff(f(x), x)/f(x), f(x).diff(x), exact=True) == \
(1/f(x) + x/f(x))*D(f(x), x) + 1/f(x)
def test_catalan():
n = Symbol('n', integer=True)
m = Symbol('n', integer=True, positive=True)
catalans = [1, 1, 2, 5, 14, 42, 132, 429, 1430, 4862, 16796, 58786]
for i, c in enumerate(catalans):
assert catalan(i) == c
assert catalan(n).rewrite(factorial).subs({n: i}) == c
assert catalan(n).rewrite(Product).subs({n: i}).doit() == c
assert catalan(x) == catalan(x)
assert catalan(2*x).rewrite(binomial) == binomial(4*x, 2*x)/(2*x + 1)
assert catalan(Rational(1, 2)).rewrite(gamma) == 8/(3*pi)
assert catalan(Rational(1, 2)).rewrite(factorial).rewrite(gamma) ==\
8 / (3 * pi)
assert catalan(3*x).rewrite(gamma) == 4**(
3*x)*gamma(3*x + Rational(1, 2))/(sqrt(pi)*gamma(3*x + 2))
assert catalan(x).rewrite(hyper) == hyper((-x + 1, -x), (2,), 1)
assert catalan(n).rewrite(factorial) == factorial(2*n) / (factorial(n + 1)
* factorial(n))
assert isinstance(catalan(n).rewrite(Product), catalan)
assert isinstance(catalan(m).rewrite(Product), Product)
assert diff(catalan(x), x) == (polygamma(
0, x + Rational(1, 2)) - polygamma(0, x + 2) + log(4))*catalan(x)
assert catalan(x).evalf() == catalan(x)
c = catalan(Rational(1, 2)).evalf()
assert str(c) == '0.848826363156775'
c = catalan(I).evalf(3)
assert sstr((re(c), im(c))) == '(0.398, -0.0209)'
def test_laguerre():
assert laguerre(0, x) == 1
assert laguerre(1, x) == -x + 1
assert laguerre(2, x) == x**2/2 - 2*x + 1
assert laguerre(3, x) == -x**3/6 + 3*x**2/2 - 3*x + 1
assert laguerre(n, oo) == (-1)**n*oo
assert laguerre(n, -oo) == oo
assert laguerre(-n, x) == exp(x)*laguerre(n - 1, -x)
X = laguerre(n, x)
assert isinstance(X, laguerre)
assert laguerre(n, 0) == 1
assert conjugate(laguerre(n, x)) == laguerre(n, conjugate(x))
assert diff(laguerre(n, x), x) == -assoc_laguerre(n - 1, 1, x)
pytest.raises(ArgumentIndexError, lambda: laguerre(n, x).fdiff(1))
pytest.raises(ValueError, lambda: laguerre(-2.1, x))
# issue sympy/sympy#10961
X = laguerre(Rational(5, 2), x)
assert isinstance(X, laguerre)
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_sympyissue_11526():
df = diff(1/(a*log((x - b)/(x - c))), x)
res = -1/(-a*c + a*b)
assert limit(df, x, oo) == res
assert limit(simplify(df), x, oo) == res
e = log((1/x - b)/(1/x - c))
assert e.as_leading_term(x) == x*(c - b)
def test_mathml_functions():
mml_1 = mp._print(sin(x))
assert mml_1.nodeName == 'apply'
assert mml_1.childNodes[0].nodeName == 'sin'
assert mml_1.childNodes[1].nodeName == 'ci'
mml_2 = mp._print(diff(sin(x), x, evaluate=False))
assert mml_2.nodeName == 'apply'
assert mml_2.childNodes[0].nodeName == 'diff'
assert mml_2.childNodes[1].nodeName == 'bvar'
assert mml_2.childNodes[1].childNodes[
0].nodeName == 'ci' # below bvar there's <ci>x/ci>
mml_3 = mp._print(diff(cos(x*y), x, evaluate=False))
assert mml_3.nodeName == 'apply'
assert mml_3.childNodes[0].nodeName == 'partialdiff'
assert mml_3.childNodes[1].nodeName == 'bvar'
assert mml_3.childNodes[1].childNodes[
0].nodeName == 'ci' # below bvar there's <ci>x/ci>
def test_vector_diff_integrate():
f = Function('f')
v = f(a)*C.i + a**2*C.j - C.k
pytest.raises(TypeError, lambda: v.diff(v))
assert Derivative(v, a) == Derivative((f(a))*C.i +
a**2*C.j + (-1)*C.k, a)
assert (diff(v, a) == v.diff(a) == Derivative(v, a).doit() ==
(Derivative(f(a), a))*C.i + 2*a*C.j)
assert (Integral(v, a) == (Integral(f(a), a))*C.i +
(Integral(a**2, a))*C.j + (Integral(-1, a))*C.k)
def test_sympyissue_4418():
a, b, c = symbols('a b c', cls=Wild, exclude=(x,))
f, g = symbols('f g', cls=Function)
eq = diff(g(x)*f(x).diff(x), x)
assert eq.match(
g(x).diff(x)*f(x).diff(x) + g(x)*f(x).diff(x, x) + c) == {c: 0}
assert eq.match(a*g(x).diff(
x)*f(x).diff(x) + b*g(x)*f(x).diff(x, x) + c) == {a: 1, b: 1, c: 0}
def test_trigsimp_issues():
# issue sympy/sympy#4625 - factor_terms works, too
assert trigsimp(sin(x)**3 + cos(x)**2*sin(x)) == sin(x)
# issue sympy/sympy#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 sympy/sympy#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 nan
assert trigsimp(eq, recursive=True) is nan
assert trigsimp(1).is_Integer
assert trigsimp(-sin(x)**4 - 2*sin(x)**2*cos(x)**2 - cos(x)**4) == -1
def test_hermite():
assert hermite(0, x) == 1
assert hermite(1, x) == 2*x
assert hermite(2, x) == 4*x**2 - 2
assert hermite(3, x) == 8*x**3 - 12*x
assert hermite(4, x) == 16*x**4 - 48*x**2 + 12
assert hermite(6, x) == 64*x**6 - 480*x**4 + 720*x**2 - 120
assert hermite(n, x) == hermite(n, x)
assert hermite(n, -x) == (-1)**n*hermite(n, x)
assert hermite(-n, x) == hermite(-n, x)
assert hermite(n, 0) == 2**n*sqrt(pi)/gamma((1 - n)/2)
assert hermite(n, oo) == oo
pytest.raises(ValueError, lambda: hermite(-1, x))
assert conjugate(hermite(n, x)) == hermite(n, conjugate(x))
assert diff(hermite(n, x), x) == 2*n*hermite(n - 1, x)
assert diff(hermite(n, x), n) == Derivative(hermite(n, x), n)
def test_airyai():
z = Symbol('z', extended_real=False)
r = Symbol('r', extended_real=True)
t = Symbol('t', negative=True)
p = Symbol('p', positive=True)
assert isinstance(airyai(z), airyai)
assert airyai(0) == cbrt(3)/(3*gamma(Rational(2, 3)))
assert airyai(oo) == 0
assert airyai(-oo) == 0
assert diff(airyai(z), z) == airyaiprime(z)
assert series(airyai(z), z, 0, 3) == (
3**Rational(5, 6)*gamma(Rational(1, 3))/(6*pi) - root(3, 6)*z*gamma(Rational(2, 3))/(2*pi) + O(z**3))
l = Limit(airyai(I/x)/(exp(-Rational(2, 3)*(I/x)**Rational(3, 2))*sqrt(pi*sqrt(I/x))/2), x, 0)
assert l.doit() == l # cover _airyais._eval_aseries
assert airyai(z).rewrite(hyper) == (
-3**Rational(2, 3)*z*hyper((), (Rational(4, 3),), z**3/9)/(3*gamma(Rational(1, 3))) +
cbrt(3)*hyper((), (Rational(2, 3),), z**3/9)/(3*gamma(Rational(2, 3))))
assert isinstance(airyai(z).rewrite(besselj), airyai)
assert airyai(t).rewrite(besselj) == (
sqrt(-t)*(besselj(-Rational(1, 3), 2*(-t)**Rational(3, 2)/3) +
besselj(Rational(1, 3), 2*(-t)**Rational(3, 2)/3))/3)
assert airyai(z).rewrite(besseli) == (
-z*besseli(Rational(1, 3), 2*z**Rational(3, 2)/3)/(3*cbrt(z**Rational(3, 2))) +
cbrt(z**Rational(3, 2))*besseli(-Rational(1, 3), 2*z**Rational(3, 2)/3)/3)
assert airyai(p).rewrite(besseli) == (
sqrt(p)*(besseli(-Rational(1, 3), 2*p**Rational(3, 2)/3) -
besseli(Rational(1, 3), 2*p**Rational(3, 2)/3))/3)
assert expand_func(airyai(2*cbrt(3*z**5))) == (
-sqrt(3)*(-1 + cbrt(z**5)/z**Rational(5, 3))*airybi(2*cbrt(3)*z**Rational(5, 3))/6 +
(1 + cbrt(z**5)/z**Rational(5, 3))*airyai(2*cbrt(3)*z**Rational(5, 3))/2)
assert expand_func(airyai(x*y)) == airyai(x*y)
assert expand_func(airyai(log(x))) == airyai(log(x))
assert expand_func(airyai(2*root(3*z**5, 5))) == airyai(2*root(3*z**5, 5))
assert (airyai(r).as_real_imag() ==
airyai(r).as_real_imag(deep=False) == (airyai(r), 0))
assert airyai(x).as_real_imag() == airyai(x).as_real_imag(deep=False)
assert (airyai(x).as_real_imag() ==
(airyai(re(x) - I*re(x)*abs(im(x))/abs(re(x)))/2 +
airyai(re(x) + I*re(x)*abs(im(x))/abs(re(x)))/2,
I*(airyai(re(x) - I*re(x)*abs(im(x))/abs(re(x))) -
airyai(re(x) + I*re(x)*abs(im(x))/Abs(re(x)))) *
re(x)*abs(im(x))/(2*im(x)*abs(re(x)))))
assert airyai(x).taylor_term(-1, x) == 0
def test_Li():
assert Li(2) == 0
assert Li(oo) == oo
assert isinstance(Li(z), Li)
assert diff(Li(z), z) == 1/log(z)
pytest.raises(ArgumentIndexError, lambda: Li(z).fdiff(2))
assert Li(z).rewrite(li) == li(z) - li(2)
assert Li(4).evalf(30) == Float('1.92242131492155809316615998937961', dps=30)
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(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)
def test_euler_interface():
x = Function('x')
y = Symbol('y')
t = Symbol('t')
pytest.raises(TypeError, lambda: euler())
pytest.raises(TypeError, lambda: euler(diff(x(t), t)*y(t), [x(t), y]))
pytest.raises(ValueError, lambda: euler(diff(x(t), t)*x(y), [x(t), x(y)]))
pytest.raises(TypeError, lambda: euler(diff(x(t), t)**2, x(0)))
pytest.raises(TypeError, lambda: euler(1, y))
assert euler(diff(x(t), t)**2/2, {x(t)}) == [Eq(-diff(x(t), t, t))]
assert euler(diff(x(t), t)**2/2, x(t), {t}) == [Eq(-diff(x(t), t, t))]
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)
def test_euler_interface():
x = Function('x')
y = Symbol('y')
t = Symbol('t')
pytest.raises(TypeError, lambda: euler())
pytest.raises(TypeError, lambda: euler(diff(x(t), t) * y(t), [x(t), y]))
pytest.raises(ValueError,
lambda: euler(diff(x(t), t) * x(y), [x(t), x(y)]))
pytest.raises(TypeError, lambda: euler(diff(x(t), t)**2, x(0)))
pytest.raises(TypeError, lambda: euler(1, y))
assert euler(diff(x(t), t)**2 / 2, {x(t)}) == [Eq(-diff(x(t), t, t))]
assert euler(diff(x(t), t)**2 / 2, x(t), {t}) == [Eq(-diff(x(t), t, t))]
def test_Ynm():
# http://en.wikipedia.org/wiki/Spherical_harmonics
th, ph = Symbol("theta", extended_real=True), Symbol("phi", extended_real=True)
from diofant.abc import n, m
assert Ynm(0, 0, th, ph).expand(func=True) == 1/(2*sqrt(pi))
assert Ynm(1, -1, th, ph) == -exp(-2*I*ph)*Ynm(1, 1, th, ph)
assert Ynm(1, -1, th, ph).expand(func=True) == sqrt(6)*sin(th)*exp(-I*ph)/(4*sqrt(pi))
assert Ynm(1, -1, th, ph).expand(func=True) == sqrt(6)*sin(th)*exp(-I*ph)/(4*sqrt(pi))
assert Ynm(1, 0, th, ph).expand(func=True) == sqrt(3)*cos(th)/(2*sqrt(pi))
assert Ynm(1, 1, th, ph).expand(func=True) == -sqrt(6)*sin(th)*exp(I*ph)/(4*sqrt(pi))
assert Ynm(2, 0, th, ph).expand(func=True) == 3*sqrt(5)*cos(th)**2/(4*sqrt(pi)) - sqrt(5)/(4*sqrt(pi))
assert Ynm(2, 1, th, ph).expand(func=True) == -sqrt(30)*sin(th)*exp(I*ph)*cos(th)/(4*sqrt(pi))
assert Ynm(2, -2, th, ph).expand(func=True) == (-sqrt(30)*exp(-2*I*ph)*cos(th)**2/(8*sqrt(pi))
+ sqrt(30)*exp(-2*I*ph)/(8*sqrt(pi)))
assert Ynm(2, 2, th, ph).expand(func=True) == (-sqrt(30)*exp(2*I*ph)*cos(th)**2/(8*sqrt(pi))
+ sqrt(30)*exp(2*I*ph)/(8*sqrt(pi)))
assert diff(Ynm(n, m, th, ph), th) == (m*cot(th)*Ynm(n, m, th, ph)
+ sqrt((-m + n)*(m + n + 1))*exp(-I*ph)*Ynm(n, m + 1, th, ph))
assert diff(Ynm(n, m, th, ph), ph) == I*m*Ynm(n, m, th, ph)
pytest.raises(ArgumentIndexError, lambda: Ynm(n, m, th, ph).fdiff(1))
assert conjugate(Ynm(n, m, th, ph)) == (-1)**(2*m)*exp(-2*I*m*ph)*Ynm(n, m, th, ph)
assert Ynm(n, m, -th, ph) == Ynm(n, m, th, ph)
assert Ynm(n, m, th, -ph) == exp(-2*I*m*ph)*Ynm(n, m, th, ph)
assert Ynm(n, -m, th, ph) == (-1)**m*exp(-2*I*m*ph)*Ynm(n, m, th, ph)
assert (Ynm(n, m, th, ph).rewrite(sin) ==
Ynm(n, m, th, ph).rewrite(cos) ==
exp(I*m*ph)*sqrt((2*n + 1)*factorial(-m + n)/factorial(m + n)) *
assoc_legendre(n, m, cos(th))/(2*sqrt(pi)))
assert (Ynm(n, m, th, ph).as_real_imag() ==
(sqrt((2*n + 1)*factorial(-m + n)/factorial(m + n))*cos(m*ph) *
assoc_legendre(n, m, cos(th))/(2*sqrt(pi)),
sqrt((2*n + 1)*factorial(-m + n)/factorial(m + n))*sin(m*ph) *
assoc_legendre(n, m, cos(th))/(2*sqrt(pi))))
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))
assert (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_airybiprime():
z = Symbol('z', extended_real=False)
t = Symbol('t', negative=True)
p = Symbol('p', positive=True)
assert isinstance(airybiprime(z), airybiprime)
assert airybiprime(0) == root(3, 6) / gamma(Rational(1, 3))
assert airybiprime(oo) == oo
assert airybiprime(-oo) == 0
assert diff(airybiprime(z), z) == z * airybi(z)
assert series(airybiprime(z), z, 0,
3) == (root(3, 6) / gamma(Rational(1, 3)) +
3**Rational(5, 6) * z**2 /
(6 * gamma(Rational(2, 3))) + O(z**3))
assert airybiprime(z).rewrite(hyper) == (
3**Rational(5, 6) * z**2 * hyper((), (Rational(5, 3), ), z**3 / 9) /
(6 * gamma(Rational(2, 3))) + root(3, 6) * hyper(
(), (Rational(1, 3), ), z**3 / 9) / gamma(Rational(1, 3)))
assert isinstance(airybiprime(z).rewrite(besselj), airybiprime)
assert (airybiprime(t).rewrite(besselj) == -sqrt(3) * t *
(besselj(-Rational(2, 3), 2 * (-t)**Rational(3, 2) / 3) +
besselj(Rational(2, 3), 2 * (-t)**Rational(3, 2) / 3)) / 3)
assert airybiprime(z).rewrite(besseli) == (
sqrt(3) * (z**2 * besseli(Rational(2, 3), 2 * z**Rational(3, 2) / 3) /
(z**Rational(3, 2))**Rational(2, 3) +
(z**Rational(3, 2))**Rational(2, 3) *
besseli(-Rational(2, 3), 2 * z**Rational(3, 2) / 3)) / 3)
assert airybiprime(p).rewrite(besseli) == (
sqrt(3) * p * (besseli(-Rational(2, 3), 2 * p**Rational(3, 2) / 3) +
besseli(Rational(2, 3), 2 * p**Rational(3, 2) / 3)) / 3)
assert airybiprime(p).rewrite(besselj) == airybiprime(p)
assert expand_func(airybiprime(
2 *
cbrt(3 * z**5))) == (sqrt(3) * (z**Rational(5, 3) / cbrt(z**5) - 1) *
airyaiprime(2 * cbrt(3) * z**Rational(5, 3)) / 2 +
(z**Rational(5, 3) / cbrt(z**5) + 1) *
airybiprime(2 * cbrt(3) * z**Rational(5, 3)) / 2)
assert expand_func(airybiprime(x * y)) == airybiprime(x * y)
assert expand_func(airybiprime(log(x))) == airybiprime(log(x))
assert expand_func(airybiprime(2 * root(3 * z**5, 5))) == airybiprime(
2 * root(3 * z**5, 5))
assert airybiprime(-2).evalf(50) == Float(
'0.27879516692116952268509756941098324140300059345163131', dps=50)
def test_Ynm():
# https//en.wikipedia.org/wiki/Spherical_harmonics
th, ph = Symbol("theta", extended_real=True), Symbol("phi", extended_real=True)
assert Ynm(0, 0, th, ph).expand(func=True) == 1/(2*sqrt(pi))
assert Ynm(1, -1, th, ph) == -exp(-2*I*ph)*Ynm(1, 1, th, ph)
assert Ynm(1, -1, th, ph).expand(func=True) == sqrt(6)*sin(th)*exp(-I*ph)/(4*sqrt(pi))
assert Ynm(1, -1, th, ph).expand(func=True) == sqrt(6)*sin(th)*exp(-I*ph)/(4*sqrt(pi))
assert Ynm(1, 0, th, ph).expand(func=True) == sqrt(3)*cos(th)/(2*sqrt(pi))
assert Ynm(1, 1, th, ph).expand(func=True) == -sqrt(6)*sin(th)*exp(I*ph)/(4*sqrt(pi))
assert Ynm(2, 0, th, ph).expand(func=True) == 3*sqrt(5)*cos(th)**2/(4*sqrt(pi)) - sqrt(5)/(4*sqrt(pi))
assert Ynm(2, 1, th, ph).expand(func=True) == -sqrt(30)*sin(th)*exp(I*ph)*cos(th)/(4*sqrt(pi))
assert Ynm(2, -2, th, ph).expand(func=True) == (-sqrt(30)*exp(-2*I*ph)*cos(th)**2/(8*sqrt(pi))
+ sqrt(30)*exp(-2*I*ph)/(8*sqrt(pi)))
assert Ynm(2, 2, th, ph).expand(func=True) == (-sqrt(30)*exp(2*I*ph)*cos(th)**2/(8*sqrt(pi))
+ sqrt(30)*exp(2*I*ph)/(8*sqrt(pi)))
assert diff(Ynm(n, m, th, ph), th) == (m*cot(th)*Ynm(n, m, th, ph)
+ sqrt((-m + n)*(m + n + 1))*exp(-I*ph)*Ynm(n, m + 1, th, ph))
assert diff(Ynm(n, m, th, ph), ph) == I*m*Ynm(n, m, th, ph)
pytest.raises(ArgumentIndexError, lambda: Ynm(n, m, th, ph).fdiff(1))
assert conjugate(Ynm(n, m, th, ph)) == (-1)**(2*m)*exp(-2*I*m*ph)*Ynm(n, m, th, ph)
assert Ynm(n, m, -th, ph) == Ynm(n, m, th, ph)
assert Ynm(n, m, th, -ph) == exp(-2*I*m*ph)*Ynm(n, m, th, ph)
assert Ynm(n, -m, th, ph) == (-1)**m*exp(-2*I*m*ph)*Ynm(n, m, th, ph)
assert (Ynm(n, m, th, ph).rewrite(sin) ==
Ynm(n, m, th, ph).rewrite(cos) ==
exp(I*m*ph)*sqrt((2*n + 1)*factorial(-m + n)/factorial(m + n)) *
assoc_legendre(n, m, cos(th))/(2*sqrt(pi)))
assert (Ynm(n, m, th, ph).as_real_imag() ==
(sqrt((2*n + 1)*factorial(-m + n)/factorial(m + n))*cos(m*ph) *
assoc_legendre(n, m, cos(th))/(2*sqrt(pi)),
sqrt((2*n + 1)*factorial(-m + n)/factorial(m + n))*sin(m*ph) *
assoc_legendre(n, m, cos(th))/(2*sqrt(pi))))
def test_airyaiprime():
z = Symbol('z', extended_real=False)
t = Symbol('t', negative=True)
p = Symbol('p', positive=True)
assert isinstance(airyaiprime(z), airyaiprime)
assert airyaiprime(0) == -3**Rational(2, 3) / (3 * gamma(Rational(1, 3)))
assert airyaiprime(oo) == 0
assert diff(airyaiprime(z), z) == z * airyai(z)
assert series(airyaiprime(z), z, 0,
3) == (-3**Rational(2, 3) / (3 * gamma(Rational(1, 3))) +
cbrt(3) * z**2 / (6 * gamma(Rational(2, 3))) +
O(z**3))
assert airyaiprime(z).rewrite(hyper) == (
cbrt(3) * z**2 * hyper((), (Rational(5, 3), ), z**3 / 9) /
(6 * gamma(Rational(2, 3))) - 3**Rational(2, 3) * hyper(
(), (Rational(1, 3), ), z**3 / 9) / (3 * gamma(Rational(1, 3))))
assert isinstance(airyaiprime(z).rewrite(besselj), airyaiprime)
assert (airyaiprime(t).rewrite(besselj) == t *
(besselj(-Rational(2, 3), 2 * (-t)**Rational(3, 2) / 3) -
besselj(Rational(2, 3), 2 * (-t)**Rational(3, 2) / 3)) / 3)
assert airyaiprime(z).rewrite(besseli) == (
z**2 * besseli(Rational(2, 3), 2 * z**Rational(3, 2) / 3) /
(3 * (z**Rational(3, 2))**Rational(2, 3)) -
(z**Rational(3, 2))**Rational(2, 3) *
besseli(-Rational(1, 3), 2 * z**Rational(3, 2) / 3) / 3)
assert airyaiprime(p).rewrite(besseli) == (
p * (-besseli(-Rational(2, 3), 2 * p**Rational(3, 2) / 3) +
besseli(Rational(2, 3), 2 * p**Rational(3, 2) / 3)) / 3)
assert airyaiprime(p).rewrite(besselj) == airyaiprime(p)
assert expand_func(airyaiprime(
2 *
cbrt(3 * z**5))) == (sqrt(3) * (z**Rational(5, 3) / cbrt(z**5) - 1) *
airybiprime(2 * cbrt(3) * z**Rational(5, 3)) / 6 +
(z**Rational(5, 3) / cbrt(z**5) + 1) *
airyaiprime(2 * cbrt(3) * z**Rational(5, 3)) / 2)
assert expand_func(airyaiprime(x * y)) == airyaiprime(x * y)
assert expand_func(airyaiprime(log(x))) == airyaiprime(log(x))
assert expand_func(airyaiprime(2 * root(3 * z**5, 5))) == airyaiprime(
2 * root(3 * z**5, 5))
assert airyaiprime(-2).evalf(50) == Float(
'0.61825902074169104140626429133247528291577794512414753', dps=50)
def scalar_potential(field, coord_sys):
"""
Returns the scalar potential function of a field in a given
coordinate system (without the added integration constant).
Parameters
==========
field : Vector
The vector field whose scalar potential function is to be
calculated
coord_sys : CoordSysCartesian
The coordinate system to do the calculation in
Examples
========
>>> from diofant.vector import CoordSysCartesian
>>> from diofant.vector import scalar_potential, gradient
>>> R = CoordSysCartesian('R')
>>> scalar_potential(R.k, R) == R.z
True
>>> scalar_field = 2*R.x**2*R.y*R.z
>>> grad_field = gradient(scalar_field, R)
>>> scalar_potential(grad_field, R)
2*R.x**2*R.y*R.z
"""
# Check whether field is conservative
if not is_conservative(field):
raise ValueError("Field is not conservative")
if field == Vector.zero:
return Integer(0)
# Express the field exntirely in coord_sys
# Subsitute coordinate variables also
if not isinstance(coord_sys, CoordSysCartesian):
raise TypeError("coord_sys must be a CoordSysCartesian")
field = express(field, coord_sys, variables=True)
dimensions = coord_sys.base_vectors()
scalars = coord_sys.base_scalars()
# Calculate scalar potential function
temp_function = integrate(field.dot(dimensions[0]), scalars[0])
for i, dim in enumerate(dimensions[1:]):
partial_diff = diff(temp_function, scalars[i + 1])
partial_diff = field.dot(dim) - partial_diff
temp_function += integrate(partial_diff, scalars[i + 1])
return temp_function
def test_sympyissue_4418():
a, b, c = symbols('a b c', cls=Wild, exclude=(x, ))
f, g = symbols('f g', cls=Function)
eq = diff(g(x) * f(x).diff(x), x)
assert eq.match(g(x).diff(x) * f(x).diff(x) + g(x) * f(x).diff(x, x) +
c) == {
c: 0
}
assert eq.match(a * g(x).diff(x) * f(x).diff(x) +
b * g(x) * f(x).diff(x, x) + c) == {
a: 1,
b: 1,
c: 0
}
def test_sympyissue_19453():
beta = Symbol('beta', real=True, positive=True)
h = Symbol('h', real=True, positive=True)
m = Symbol('m', real=True, positive=True)
w = Symbol('omega', real=True, positive=True)
g = Symbol('g', real=True, positive=True)
q = 3*h**2*beta*g*exp(h*beta*w/2)
p = m**2*w**2
s = exp(h*beta*w) - 1
z = (-q/(4*p*s) - q/(2*p*s**2) -
q*(exp(h*beta*w) + 1)/(2*p*s**3) + exp(h*beta*w/2)/s)
e = -diff(log(z), beta)
assert limit(e - h*w/2, beta, oo) == 0
assert limit(e.simplify() - h*w/2, beta, oo) == 0
def test_pde_separate_add():
x, y, z, t = symbols("x,y,z,t")
F, T, X, Y, Z, u = map(Function, 'FTXYZu')
eq = Eq(diff(u(x, t), x), diff(u(x, t), t)*exp(u(x, t)))
res = pde_separate_add(eq, u(x, t), [X(x), T(t)])
assert res == [diff(X(x), x)*exp(-X(x)), diff(T(t), t)*exp(T(t))]
eq = Eq(u(x, y).diff(x), -exp(u(x, y).diff(y)))
res = pde_separate_add(eq, u(x, y), [X(x), Y(y)])
assert res == [diff(X(x), x), -exp(diff(Y(y), y))]
def test_pde_separate_add():
x, y, z, t = symbols('x,y,z,t')
F, T, X, Y, Z, u = map(Function, 'FTXYZu')
eq = Eq(diff(u(x, t), x), diff(u(x, t), t) * exp(u(x, t)))
res = pde_separate_add(eq, u(x, t), [X(x), T(t)])
assert res == [diff(X(x), x) * exp(-X(x)), diff(T(t), t) * exp(T(t))]
eq = Eq(u(x, y).diff(x), -exp(u(x, y).diff(y)))
res = pde_separate_add(eq, u(x, y), [X(x), Y(y)])
assert res == [diff(X(x), x), -exp(diff(Y(y), y))]
def test_components():
assert components(x*y, x) == {x}
assert components(1/(x + y), x) == {x}
assert components(sin(x), x) == {sin(x), x}
assert components(sin(x)*sqrt(log(x)), x) == \
{log(x), sin(x), sqrt(log(x)), x}
assert components(x*sin(exp(x)*y), x) == \
{sin(y*exp(x)), x, exp(x)}
assert components(x**Rational(17, 54)/sqrt(sin(x)), x) == \
{sin(x), root(x, 54), sqrt(sin(x)), x}
assert components(f(x), x) == \
{x, f(x)}
assert components(Derivative(f(x), x), x) == \
{x, f(x), Derivative(f(x), x)}
assert components(f(x)*diff(f(x), x), x) == \
{x, f(x), Derivative(f(x), x), Derivative(f(x), x)}
def test_components():
assert components(x * y, x) == {x}
assert components(1 / (x + y), x) == {x}
assert components(sin(x), x) == {sin(x), x}
assert components(sin(x)*sqrt(log(x)), x) == \
{log(x), sin(x), sqrt(log(x)), x}
assert components(x*sin(exp(x)*y), x) == \
{sin(y*exp(x)), x, exp(x)}
assert components(x**Rational(17, 54)/sqrt(sin(x)), x) == \
{sin(x), root(x, 54), sqrt(sin(x)), x}
assert components(f(x), x) == \
{x, f(x)}
assert components(Derivative(f(x), x), x) == \
{x, f(x), Derivative(f(x), x)}
assert components(f(x)*diff(f(x), x), x) == \
{x, f(x), Derivative(f(x), x), Derivative(f(x), x)}
def test_match_deriv_bug1():
n = Function('n')
l = Function('l')
p = Wild('p')
e = diff(l(x), x)/x - diff(diff(n(x), x), x)/2 - \
diff(n(x), x)**2/4 + diff(n(x), x)*diff(l(x), x)/4
e = e.subs({n(x): -l(x)}).doit()
t = x*exp(-l(x))
t2 = t.diff(x, x)/t
assert e.match( (p*t2).expand() ) == {p: -Rational(1, 2)}
def test_match_deriv_bug1():
n = Function('n')
l = Function('l')
p = Wild('p')
e = diff(l(x), x)/x - diff(diff(n(x), x), x)/2 - \
diff(n(x), x)**2/4 + diff(n(x), x)*diff(l(x), x)/4
e = e.subs({n(x): -l(x)}).doit()
t = x * exp(-l(x))
t2 = t.diff(x, x) / t
assert e.match((p * t2).expand()) == {p: -Rational(1, 2)}
def test_airyai():
z = Symbol('z', extended_real=False)
t = Symbol('t', negative=True)
p = Symbol('p', positive=True)
assert isinstance(airyai(z), airyai)
assert airyai(0) == 3**Rational(1, 3) / (3 * gamma(Rational(2, 3)))
assert airyai(oo) == 0
assert airyai(-oo) == 0
assert diff(airyai(z), z) == airyaiprime(z)
assert series(airyai(z), z, 0,
3) == (3**Rational(5, 6) * gamma(Rational(1, 3)) / (6 * pi) -
3**Rational(1, 6) * z * gamma(Rational(2, 3)) /
(2 * pi) + O(z**3))
assert airyai(z).rewrite(hyper) == (-3**Rational(2, 3) * z * hyper(
(), (Rational(4, 3), ),
z**Integer(3) / 9) / (3 * gamma(Rational(1, 3))) +
3**Rational(1, 3) * hyper(
(), (Rational(2, 3), ),
z**Integer(3) / 9) /
(3 * gamma(Rational(2, 3))))
assert isinstance(airyai(z).rewrite(besselj), airyai)
assert airyai(t).rewrite(besselj) == (
sqrt(-t) * (besselj(-Rational(1, 3), 2 * (-t)**Rational(3, 2) / 3) +
besselj(Rational(1, 3), 2 * (-t)**Rational(3, 2) / 3)) / 3)
assert airyai(z).rewrite(besseli) == (
-z * besseli(Rational(1, 3), 2 * z**Rational(3, 2) / 3) /
(3 * (z**Rational(3, 2))**Rational(1, 3)) +
(z**Rational(3, 2))**Rational(1, 3) *
besseli(-Rational(1, 3), 2 * z**Rational(3, 2) / 3) / 3)
assert airyai(p).rewrite(besseli) == (
sqrt(p) * (besseli(-Rational(1, 3), 2 * p**Rational(3, 2) / 3) -
besseli(Rational(1, 3), 2 * p**Rational(3, 2) / 3)) / 3)
assert expand_func(airyai(2 * (3 * z**5)**Rational(1, 3))) == (
-sqrt(3) * (-1 + (z**5)**Rational(1, 3) / z**Rational(5, 3)) *
airybi(2 * 3**Rational(1, 3) * z**Rational(5, 3)) / 6 +
(1 + (z**5)**Rational(1, 3) / z**Rational(5, 3)) *
airyai(2 * 3**Rational(1, 3) * z**Rational(5, 3)) / 2)
def test_catalan():
n = Symbol('n', integer=True)
m = Symbol('n', integer=True, positive=True)
catalans = [1, 1, 2, 5, 14, 42, 132, 429, 1430, 4862, 16796, 58786]
for i, c in enumerate(catalans):
assert catalan(i) == c
assert catalan(n).rewrite(factorial).subs({n: i}) == c
assert catalan(n).rewrite(Product).subs({n: i}).doit() == c
assert catalan(x) == catalan(x)
assert catalan(2 *
x).rewrite(binomial) == binomial(4 * x, 2 * x) / (2 * x + 1)
assert catalan(Rational(1, 2)).rewrite(gamma) == 8 / (3 * pi)
assert catalan(Rational(1, 2)).rewrite(factorial).rewrite(gamma) ==\
8 / (3 * pi)
assert catalan(3 * x).rewrite(gamma) == 4**(
3 * x) * gamma(3 * x + Rational(1, 2)) / (sqrt(pi) * gamma(3 * x + 2))
assert catalan(x).rewrite(hyper) == hyper((-x + 1, -x), (2, ), 1)
assert catalan(n).rewrite(factorial) == factorial(
2 * n) / (factorial(n + 1) * factorial(n))
assert isinstance(catalan(n).rewrite(Product), catalan)
assert isinstance(catalan(m).rewrite(Product), Product)
assert diff(catalan(x), x) == (polygamma(0, x + Rational(1, 2)) -
polygamma(0, x + 2) + log(4)) * catalan(x)
assert catalan(x).evalf() == catalan(x)
c = catalan(Rational(1, 2)).evalf()
assert str(c) == '0.848826363156775'
c = catalan(I).evalf(3)
assert sstr((re(c), im(c))) == '(0.398, -0.0209)'
# issue sympy/sympy#8601
n = Symbol('n', integer=True, negative=True)
assert catalan(n - 1) == 0
assert catalan(Rational(-1, 2)) == zoo
assert catalan(-1) == Rational(-1, 2)
c1 = catalan(-5.6).evalf(strict=False)
assert str(c1) == '6.93334070531408e-5'
c2 = catalan(-35.4).evalf(strict=False)
assert str(c2) == '-4.14189164517449e-24'
def test_airybi():
z = Symbol('z', extended_real=False)
t = Symbol('t', negative=True)
p = Symbol('p', positive=True)
assert isinstance(airybi(z), airybi)
assert airybi(0) == 3**Rational(5, 6)/(3*gamma(Rational(2, 3)))
assert airybi(oo) == oo
assert airybi(-oo) == 0
assert diff(airybi(z), z) == airybiprime(z)
assert airybi(z).series(z, 0, 3) == (
cbrt(3)*gamma(Rational(1, 3))/(2*pi) + 3**Rational(2, 3)*z*gamma(Rational(2, 3))/(2*pi) + O(z**3))
l = Limit(airybi(I/x)/(exp(Rational(2, 3)*(I/x)**Rational(3, 2))*sqrt(pi*sqrt(I/x))), x, 0)
assert l.doit() == l
assert airybi(z).rewrite(hyper) == (
root(3, 6)*z*hyper((), (Rational(4, 3),), z**3/9)/gamma(Rational(1, 3)) +
3**Rational(5, 6)*hyper((), (Rational(2, 3),), z**3/9)/(3*gamma(Rational(2, 3))))
assert isinstance(airybi(z).rewrite(besselj), airybi)
assert (airybi(t).rewrite(besselj) ==
sqrt(3)*sqrt(-t)*(besselj(-1/3, 2*(-t)**Rational(3, 2)/3) -
besselj(Rational(1, 3),
2*(-t)**Rational(3, 2)/3))/3)
assert airybi(z).rewrite(besseli) == (
sqrt(3)*(z*besseli(Rational(1, 3), 2*z**Rational(3, 2)/3)/cbrt(z**Rational(3, 2)) +
cbrt(z**Rational(3, 2))*besseli(-Rational(1, 3), 2*z**Rational(3, 2)/3))/3)
assert airybi(p).rewrite(besseli) == (
sqrt(3)*sqrt(p)*(besseli(-Rational(1, 3), 2*p**Rational(3, 2)/3) +
besseli(Rational(1, 3), 2*p**Rational(3, 2)/3))/3)
assert airybi(p).rewrite(besselj) == airybi(p)
assert expand_func(airybi(2*cbrt(3*z**5))) == (
sqrt(3)*(1 - cbrt(z**5)/z**Rational(5, 3))*airyai(2*cbrt(3)*z**Rational(5, 3))/2 +
(1 + cbrt(z**5)/z**Rational(5, 3))*airybi(2*cbrt(3)*z**Rational(5, 3))/2)
assert expand_func(airybi(x*y)) == airybi(x*y)
assert expand_func(airybi(log(x))) == airybi(log(x))
assert expand_func(airybi(2*root(3*z**5, 5))) == airybi(2*root(3*z**5, 5))
assert airybi(x).taylor_term(-1, x) == 0
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)
assert diff(f(x, y, z), x, 3) == Derivative(f(x, y, z), x, 3)
# issue sympy/sympy#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)
def test_li():
z = Symbol('z')
zr = Symbol('z', extended_real=True)
zp = Symbol('z', positive=True)
zn = Symbol('z', negative=True)
assert li(0) == 0
assert li(1) == -oo
assert li(oo) == oo
assert isinstance(li(z), li)
assert diff(li(z), z) == 1 / log(z)
pytest.raises(ArgumentIndexError, lambda: li(z).fdiff(2))
assert conjugate(li(z)) == li(conjugate(z))
assert conjugate(li(-zr)) == li(-zr)
assert conjugate(li(-zp)) == conjugate(li(-zp))
assert conjugate(li(zn)) == conjugate(li(zn))
assert li(z).rewrite(Li) == Li(z) + li(2)
assert li(z).rewrite(Ei) == Ei(log(z))
assert li(z).rewrite(uppergamma) == (-log(1 / log(z)) / 2 - log(-log(z)) +
log(log(z)) / 2 - expint(1, -log(z)))
assert li(z).rewrite(Si) == (-log(I * log(z)) - log(1 / log(z)) / 2 +
log(log(z)) / 2 + Ci(I * log(z)) +
Shi(log(z)))
assert li(z).rewrite(Ci) == (-log(I * log(z)) - log(1 / log(z)) / 2 +
log(log(z)) / 2 + Ci(I * log(z)) +
Shi(log(z)))
assert li(z).rewrite(Shi) == (-log(1 / log(z)) / 2 + log(log(z)) / 2 +
Chi(log(z)) - Shi(log(z)))
assert li(z).rewrite(Chi) == (-log(1 / log(z)) / 2 + log(log(z)) / 2 +
Chi(log(z)) - Shi(log(z)))
assert li(z).rewrite(hyper) == (log(z) * hyper(
(1, 1),
(2, 2), log(z)) - log(1 / log(z)) / 2 + log(log(z)) / 2 + EulerGamma)
assert li(z).rewrite(meijerg) == (-log(1 / log(z)) / 2 - log(-log(z)) +
log(log(z)) / 2 - meijerg(
((), (1, )), ((0, 0), ()), -log(z)))
def main():
t = ReferenceSimplex(2)
fe = Lagrange(2, 2)
u = 0
# compute u = sum_i u_i N_i
us = []
for i in range(0, fe.nbf()):
ui = Symbol("u_%d" % i)
us.append(ui)
u += ui * fe.N[i]
J = zeros(fe.nbf())
for i in range(0, fe.nbf()):
Fi = u * fe.N[i]
print(Fi)
for j in range(0, fe.nbf()):
uj = us[j]
integrands = diff(Fi, uj)
print(integrands)
J[j, i] = t.integrate(integrands)
pprint(J)
def test_assoc_laguerre():
# generalized Laguerre polynomials:
assert assoc_laguerre(0, alpha, x) == 1
assert assoc_laguerre(1, alpha, x) == -x + alpha + 1
assert assoc_laguerre(2, alpha, x).expand() == \
(x**2/2 - (alpha + 2)*x + (alpha + 2)*(alpha + 1)/2).expand()
assert assoc_laguerre(3, alpha, x).expand() == \
(-x**3/6 + (alpha + 3)*x**2/2 - (alpha + 2)*(alpha + 3)*x/2 +
(alpha + 1)*(alpha + 2)*(alpha + 3)/6).expand()
# Test the lowest 10 polynomials with laguerre_poly, to make sure it works:
for i in range(10):
assert assoc_laguerre(i, 0, x).expand() == laguerre_poly(i, x)
X = assoc_laguerre(n, m, x)
assert isinstance(X, assoc_laguerre)
assert assoc_laguerre(n, 0, x) == laguerre(n, x)
assert assoc_laguerre(n, alpha, 0) == binomial(alpha + n, alpha)
p = Symbol('p', positive=True)
assert assoc_laguerre(p, alpha, oo) == (-1)**p * oo
assert assoc_laguerre(p, alpha, -oo) == oo
assert diff(assoc_laguerre(n, alpha, x), x) == \
-assoc_laguerre(n - 1, alpha + 1, x)
pytest.raises(ArgumentIndexError, lambda: assoc_laguerre(n, m, x).fdiff(1))
assert conjugate(assoc_laguerre(n, alpha, x)) == \
assoc_laguerre(n, conjugate(alpha), conjugate(x))
pytest.raises(ValueError, lambda: assoc_laguerre(-2.1, alpha, x))
# issue sympy/sympy#10961
X = assoc_laguerre(Rational(5, 2), alpha, x)
assert isinstance(X, assoc_laguerre)
def test_heurisch_symbolic_coeffs():
assert heurisch(1 / (x + y), x) == log(x + y)
assert heurisch(1 / (x + sqrt(2)), x) == log(x + sqrt(2))
assert simplify(diff(heurisch(log(x + y + z), y), y)) == log(x + y + z)
def test_derivative_subs_self_bug():
d = diff(f(x), x)
assert d.subs({d: y}) == y
def test_laguerre_2():
# This fails due to issue for Sum, like issue sympy/sympy#5539
assert diff(assoc_laguerre(n, alpha, x), alpha) == \
Sum(assoc_laguerre(k, alpha, x)/(-alpha + n), (k, 0, n - 1))
def test_pde_separate_mul():
x, y, z, t = symbols('x,y,z,t')
c = Symbol('C', extended_real=True)
Phi = Function('Phi')
F, R, T, X, Y, Z, u = map(Function, 'FRTXYZu')
r, theta, z = symbols('r,theta,z')
# Something simple :)
eq = Eq(diff(F(x, y, z), x) + diff(F(x, y, z), y) + diff(F(x, y, z), z), 0)
# Duplicate arguments in functions
pytest.raises(
ValueError,
lambda: pde_separate_mul(eq, F(x, y, z), [X(x), u(z, z)]))
# Wrong number of arguments
pytest.raises(ValueError,
lambda: pde_separate_mul(eq, F(x, y, z), [X(x), Y(y)]))
# Wrong variables: [x, y] -> [x, z]
pytest.raises(
ValueError,
lambda: pde_separate_mul(eq, F(x, y, z), [X(t), Y(x, y)]))
assert pde_separate_mul(eq, F(x, y, z), [Y(y), u(x, z)]) == \
[diff(Y(y), y)/Y(y), -diff(u(x, z), x)/u(x, z) - diff(u(x, z), z)/u(x, z)]
assert pde_separate_mul(eq, F(x, y, z), [X(x), Y(y), Z(z)]) == \
[diff(X(x), x)/X(x), -diff(Z(z), z)/Z(z) - diff(Y(y), y)/Y(y)]
# wave equation
wave = Eq(diff(u(x, t), t, t), c**2 * diff(u(x, t), x, x))
res = pde_separate_mul(wave, u(x, t), [X(x), T(t)])
assert res == [diff(X(x), x, x) / X(x), diff(T(t), t, t) / (c**2 * T(t))]
# Laplace equation in cylindrical coords
eq = Eq(
1 / r * diff(Phi(r, theta, z), r) + diff(Phi(r, theta, z), r, 2) +
1 / r**2 * diff(Phi(r, theta, z), theta, 2) +
diff(Phi(r, theta, z), z, 2), 0)
# Separate z
res = pde_separate_mul(eq, Phi(r, theta, z), [Z(z), u(theta, r)])
assert res == [
diff(Z(z), z, z) / Z(z), -diff(u(theta, r), r, r) / u(theta, r) -
diff(u(theta, r), r) / (r * u(theta, r)) -
diff(u(theta, r), theta, theta) / (r**2 * u(theta, r))
]
# Lets use the result to create a new equation...
eq = Eq(res[1], c)
# ...and separate theta...
res = pde_separate_mul(eq, u(theta, r), [T(theta), R(r)])
assert res == [
diff(T(theta), theta, theta) / T(theta),
-r * diff(R(r), r) / R(r) - r**2 * diff(R(r), r, r) / R(r) - c * r**2
]
# ...or r...
res = pde_separate_mul(eq, u(theta, r), [R(r), T(theta)])
assert res == [
r * diff(R(r), r) / R(r) + r**2 * diff(R(r), r, r) / R(r) + c * r**2,
-diff(T(theta), theta, theta) / T(theta)
]
# Laplace eq in spherical coordinates
r, phi, theta, C1 = symbols('r,phi,theta,C1')
Xi = Function('Xi')
R, Phi, Theta, u = map(Function, ['R', 'Phi', 'Theta', 'u'])
eq = Eq(
diff(Xi(r, phi, theta), r, 2) + 2 / r * diff(Xi(r, phi, theta), r) +
1 / (r**2 * sin(phi)**2) * diff(Xi(r, phi, theta), theta, 2) +
cos(phi) / (r**2 * sin(phi)) * diff(Xi(r, phi, theta), phi) +
1 / r**2 * diff(Xi(r, phi, theta), phi, 2), 0)
res_theta = pde_separate(eq, Xi(r, phi, theta), [Theta(theta), u(r, phi)])
eq_left = Eq(res_theta[1], -C1)
res_theta = pde_separate(eq_left, u(r, phi), [Phi(phi), R(r)])
assert (res_theta == [
C1 / sin(phi)**2 - diff(Phi(phi), phi, phi) / Phi(phi) -
diff(Phi(phi), phi) / (Phi(phi) * tan(phi)),
r**2 * diff(R(r), r, r) / R(r) + 2 * r * diff(R(r), r) / R(r)
])
# coverage tests
assert pde_separate_mul(Eq(u(x, t).diff(x),
u(x, t).diff(x, t)), u(x, t),
[X(x), T(t)]) == [-1, -T(t) / diff(T(t), t)]
assert pde_separate(Eq((x + t) * u(x, t).diff(x),
u(x, t).diff(t)),
u(x, t), [X(x), T(t)],
strategy='mul') is None
assert pde_separate(Eq(u(x, t).diff(x),
u(x, t).diff(t) + t),
u(x, t), [X(x), T(t)],
strategy='mul') is None
assert pde_separate(Eq(u(x, t).diff(x), exp(u(x, t).diff(t))),
u(x, t), [X(x), T(t)],
strategy='mul') is None
def test_airyai():
z = Symbol('z', extended_real=False)
r = Symbol('r', extended_real=True)
t = Symbol('t', negative=True)
p = Symbol('p', positive=True)
assert isinstance(airyai(z), airyai)
assert airyai(0) == cbrt(3) / (3 * gamma(Rational(2, 3)))
assert airyai(oo) == 0
assert airyai(-oo) == 0
assert diff(airyai(z), z) == airyaiprime(z)
assert series(airyai(z), z, 0,
3) == (3**Rational(5, 6) * gamma(Rational(1, 3)) / (6 * pi) -
root(3, 6) * z * gamma(Rational(2, 3)) / (2 * pi) +
O(z**3))
l = Limit(
airyai(I / x) /
(exp(-Rational(2, 3) *
(I / x)**Rational(3, 2)) * sqrt(pi * sqrt(I / x)) / 2), x, 0)
assert l.doit() == l # cover _airyais._eval_aseries
assert airyai(z).rewrite(hyper) == (-3**Rational(2, 3) * z * hyper(
(), (Rational(4, 3), ), z**3 / 9) / (3 * gamma(Rational(1, 3))) +
cbrt(3) * hyper(
(), (Rational(2, 3), ), z**3 / 9) /
(3 * gamma(Rational(2, 3))))
assert isinstance(airyai(z).rewrite(besselj), airyai)
assert airyai(t).rewrite(besselj) == (
sqrt(-t) * (besselj(-Rational(1, 3), 2 * (-t)**Rational(3, 2) / 3) +
besselj(Rational(1, 3), 2 * (-t)**Rational(3, 2) / 3)) / 3)
assert airyai(z).rewrite(besseli) == (
-z * besseli(Rational(1, 3), 2 * z**Rational(3, 2) / 3) /
(3 * cbrt(z**Rational(3, 2))) + cbrt(z**Rational(3, 2)) *
besseli(-Rational(1, 3), 2 * z**Rational(3, 2) / 3) / 3)
assert airyai(p).rewrite(besseli) == (
sqrt(p) * (besseli(-Rational(1, 3), 2 * p**Rational(3, 2) / 3) -
besseli(Rational(1, 3), 2 * p**Rational(3, 2) / 3)) / 3)
assert expand_func(airyai(
2 *
cbrt(3 * z**5))) == (-sqrt(3) * (-1 + cbrt(z**5) / z**Rational(5, 3)) *
airybi(2 * cbrt(3) * z**Rational(5, 3)) / 6 +
(1 + cbrt(z**5) / z**Rational(5, 3)) *
airyai(2 * cbrt(3) * z**Rational(5, 3)) / 2)
assert expand_func(airyai(x * y)) == airyai(x * y)
assert expand_func(airyai(log(x))) == airyai(log(x))
assert expand_func(airyai(2 * root(3 * z**5, 5))) == airyai(
2 * root(3 * z**5, 5))
assert (airyai(r).as_real_imag() == airyai(r).as_real_imag(deep=False) ==
(airyai(r), 0))
assert airyai(x).as_real_imag() == airyai(x).as_real_imag(deep=False)
assert (airyai(x).as_real_imag() == (
airyai(re(x) - I * re(x) * abs(im(x)) / abs(re(x))) / 2 +
airyai(re(x) + I * re(x) * abs(im(x)) / abs(re(x))) / 2,
I * (airyai(re(x) - I * re(x) * abs(im(x)) / abs(re(x))) -
airyai(re(x) + I * re(x) * abs(im(x)) / Abs(re(x)))) * re(x) *
abs(im(x)) / (2 * im(x) * abs(re(x)))))
assert airyai(x).taylor_term(-1, x) == 0
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)
def test_sympyissue_3740():
f = 4 * log(x) - 2 * log(x)**2
fid = diff(integrate(f, x), x)
assert abs(f.subs(x, 42).evalf() - fid.subs(x, 42).evalf()) < 1e-10
def test_integrate_functions_1():
assert integrate(f(x) * diff(f(x), x), x) == f(x)**2 / 2
assert integrate(diff(f(x), x) / f(x), x) == log(f(x))
def test_sympyissue_5948():
assert trigsimp(diff(integrate(cos(x) / sin(x)**7, x),
x)) == cos(x) / sin(x)**7
def vdiff(f, y):
return diff(f, y)
def test_basics():
assert Integral(0, x) != 0
assert Integral(x, (x, 1, 1)) != 0
assert Integral(oo, x) != oo
assert Integral(nan, x) == nan
assert diff(Integral(y, y), x) == 0
assert diff(Integral(x, (x, 0, 1)), x) == 0
assert diff(Integral(x, x), x) == x
assert diff(Integral(t, (t, 0, x)), x) == x + Integral(0, (t, 0, x))
e = (t + 1)**2
assert diff(integrate(e, (t, 0, x)), x) == \
diff(Integral(e, (t, 0, x)), x).doit().expand() == \
((1 + x)**2).expand()
assert diff(integrate(e, (t, 0, x)), t) == \
diff(Integral(e, (t, 0, x)), t) == 0
assert diff(integrate(e, (t, 0, x)), a) == \
diff(Integral(e, (t, 0, x)), a) == 0
assert diff(integrate(e, t), a) == diff(Integral(e, t), a) == 0
assert integrate(e, (t, a, x)).diff(x) == \
Integral(e, (t, a, x)).diff(x).doit().expand()
assert Integral(e, (t, a, x)).diff(x).doit() == ((1 + x)**2)
assert integrate(e, (t, x, a)).diff(x).doit() == (-(1 + x)**2).expand()
assert integrate(t**2, (t, x, 2 * x)).diff(x) == 7 * x**2
assert Integral(x, x).atoms() == {x}
assert Integral(f(x), (x, 0, 1)).atoms() == {0, 1, x}
assert diff_test(Integral(x, (x, 3 * y))) == {y}
assert diff_test(Integral(x, (a, 3 * y))) == {x, y}
assert integrate(x, (x, oo, oo)) == 0 # issue sympy/sympy#8171
assert integrate(x, (x, -oo, -oo)) == 0
# sum integral of terms
assert integrate(y + x + exp(x), x) == x * y + x**2 / 2 + exp(x)
assert Integral(x).is_commutative
n = Symbol('n', commutative=False)
assert Integral(n + x, x).is_commutative is False