def test_derivative2():
f = Function("f")
a = Wild("a", exclude=[f, x])
b = Wild("b", exclude=[f])
e = Derivative(f(x), x)
assert e.match(Derivative(f(x), x)) == {}
assert e.match(Derivative(f(x), x, x)) is None
e = Derivative(f(x), x, x)
assert e.match(Derivative(f(x), x)) is None
assert e.match(Derivative(f(x), x, x)) == {}
e = Derivative(f(x), x) + x**2
assert e.match(a * Derivative(f(x), x) + b) == {a: 1, b: x**2}
assert e.match(a * Derivative(f(x), x, x) + b) is None
e = Derivative(f(x), x, x) + x**2
assert e.match(a * Derivative(f(x), x) + b) is None
assert e.match(a * Derivative(f(x), x, x) + b) == {a: 1, b: x**2}
def test_Derivative_bug1():
f = Function("f")
a = Wild("a", exclude=[f(x)])
b = Wild("b", exclude=[f(x)])
eq = f(x).diff(x)
assert eq.match(a * Derivative(f(x), x) + b) == {a: 1, b: 0}
def test_derivative_subs3():
x = Symbol('x')
dex = Derivative(exp(x), x)
assert Derivative(dex, x).subs(dex, exp(x)) == dex
assert dex.subs(exp(x), dex) == Derivative(exp(x), x, x)
def test_del_operator():
pytest.raises(TypeError, lambda: Del(Integer(1)))
# Tests for curl
assert (delop ^ Vector.zero ==
(Derivative(0, C.y) - Derivative(0, C.z))*C.i +
(-Derivative(0, C.x) + Derivative(0, C.z))*C.j +
(Derivative(0, C.x) - Derivative(0, C.y))*C.k)
assert ((delop ^ Vector.zero).doit() == Vector.zero ==
curl(Vector.zero, C))
assert delop.cross(Vector.zero) == delop ^ Vector.zero
assert (delop ^ i).doit() == Vector.zero
assert delop.cross(2*y**2*j, doit=True) == Vector.zero
assert delop.cross(2*y**2*j) == delop ^ 2*y**2*j
v = x*y*z * (i + j + k)
assert ((delop ^ v).doit() ==
(-x*y + x*z)*i + (x*y - y*z)*j + (-x*z + y*z)*k ==
curl(v, C))
assert delop ^ v == delop.cross(v)
assert (delop.cross(2*x**2*j) ==
(Derivative(0, C.y) - Derivative(2*C.x**2, C.z))*C.i +
(-Derivative(0, C.x) + Derivative(0, C.z))*C.j +
(-Derivative(0, C.y) + Derivative(2*C.x**2, C.x))*C.k)
assert (delop.cross(2*x**2*j, doit=True) == 4*x*k ==
curl(2*x**2*j, C))
# Tests for divergence
assert delop & Vector.zero == Integer(0) == divergence(Vector.zero, C)
assert (delop & Vector.zero).doit() == Integer(0)
assert delop.dot(Vector.zero) == delop & Vector.zero
assert (delop & i).doit() == Integer(0)
assert (delop & x**2*i).doit() == 2*x == divergence(x**2*i, C)
assert (delop.dot(v, doit=True) == x*y + y*z + z*x ==
divergence(v, C))
assert delop & v == delop.dot(v)
assert delop.dot(1/(x*y*z) * (i + j + k), doit=True) == \
- 1 / (x*y*z**2) - 1 / (x*y**2*z) - 1 / (x**2*y*z)
v = x*i + y*j + z*k
assert (delop & v == Derivative(C.x, C.x) +
Derivative(C.y, C.y) + Derivative(C.z, C.z))
assert delop.dot(v, doit=True) == 3 == divergence(v, C)
assert delop & v == delop.dot(v)
assert simplify((delop & v).doit()) == 3
# Tests for gradient
assert (delop.gradient(0, doit=True) == Vector.zero ==
gradient(0, C))
assert delop.gradient(0) == delop(0)
assert (delop(Integer(0))).doit() == Vector.zero
assert (delop(x) == (Derivative(C.x, C.x))*C.i +
(Derivative(C.x, C.y))*C.j + (Derivative(C.x, C.z))*C.k)
assert (delop(x)).doit() == i == gradient(x, C)
assert (delop(x*y*z) ==
(Derivative(C.x*C.y*C.z, C.x))*C.i +
(Derivative(C.x*C.y*C.z, C.y))*C.j +
(Derivative(C.x*C.y*C.z, C.z))*C.k)
assert (delop.gradient(x*y*z, doit=True) ==
y*z*i + z*x*j + x*y*k ==
gradient(x*y*z, C))
assert delop(x*y*z) == delop.gradient(x*y*z)
assert (delop(2*x**2)).doit() == 4*x*i
assert ((delop(a*sin(y) / x)).doit() ==
-a*sin(y)/x**2 * i + a*cos(y)/x * j)
# Tests for directional derivative
assert (Vector.zero & delop)(a) == Integer(0)
assert ((Vector.zero & delop)(a)).doit() == Integer(0)
assert ((v & delop)(Vector.zero)).doit() == Vector.zero
assert ((v & delop)(Integer(0))).doit() == Integer(0)
assert ((i & delop)(x)).doit() == 1
assert ((j & delop)(y)).doit() == 1
assert ((k & delop)(z)).doit() == 1
assert ((i & delop)(x*y*z)).doit() == y*z
assert ((v & delop)(x)).doit() == x
assert ((v & delop)(x*y*z)).doit() == 3*x*y*z
assert (v & delop)(x + y + z) == C.x + C.y + C.z
assert ((v & delop)(x + y + z)).doit() == x + y + z
assert ((v & delop)(v)).doit() == v
assert ((i & delop)(v)).doit() == i
assert ((j & delop)(v)).doit() == j
assert ((k & delop)(v)).doit() == k
assert ((v & delop)(Vector.zero)).doit() == Vector.zero
def test_derivative_numerically():
z0 = random() + I*random()
assert abs(Derivative(sin(x), x).doit_numerically(z0) - cos(z0)) < 1e-15
def test_sympyissue_11313():
# test Derivative series & as_leading_term
assert Derivative(x**3 + x**4, x).as_leading_term(x).doit() == 3*x**2
s = Derivative(sin(x), x).series(x, n=3)
assert s == Derivative(-x**3/6, x) + Derivative(x, x) + O(x**3)
assert s.doit() == 1 - x**2/2 + O(x**3)
def test_derivative_subs3():
x = Symbol('x')
dex = Derivative(exp(x), x)
assert Derivative(dex, x).subs({dex: exp(x)}) == dex
assert dex.subs({exp(x): dex}) == Derivative(exp(x), x, x)
def test_Derivative():
assert str(Derivative(x, y)) == 'Derivative(x, y)'
assert str(Derivative(x**2, x, evaluate=False)) == 'Derivative(x**2, x)'
assert str(Derivative(x**2 / y, x, y,
evaluate=False)) == 'Derivative(x**2/y, x, y)'
def test_deriv_sub_bug3():
y = Symbol('y')
f = Function('f')
pat = Derivative(f(x), x, x)
assert pat.subs({y: y**2}) == Derivative(f(x), x, x)
assert pat.subs({y: y**2}) != Derivative(f(x), x)
def test_derivative_subs2():
f_func, g_func = symbols('f g', cls=Function)
f, g = f_func(x, y, z), g_func(x, y, z)
assert Derivative(f, x, y).subs({Derivative(f, x, y): g}) == g
assert Derivative(f, y, x).subs({Derivative(f, x, y): g}) == g
assert Derivative(f, x, y).subs({Derivative(f, x): g}) == Derivative(g, y)
assert Derivative(f, x, y).subs({Derivative(f, y): g}) == Derivative(g, x)
assert (Derivative(f, x, y, z).subs({Derivative(f, x, z):
g}) == Derivative(g, y))
assert (Derivative(f, x, y, z).subs({Derivative(f, z, y):
g}) == Derivative(g, x))
assert (Derivative(f, x, y, z).subs({Derivative(f, z, y, x): g}) == g)
assert (Derivative(sin(x), x,
2).subs({Derivative(sin(x), f_func(x)):
g_func}) == Derivative(sin(x), x, 2))
# issue sympy/sympy#9135
assert (Derivative(f, x, x, y).subs({Derivative(f, y, y):
g}) == Derivative(f, x, x, y))
assert (Derivative(f, x, y, y, z).subs({Derivative(f, x, y, y, y):
g}) == Derivative(f, x, y, y, z))
assert Derivative(f, x, y).subs({Derivative(f_func(x), x, y):
g}) == Derivative(f, x, y)
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 + b + n + 1)*jacobi(n - 1, a + 1, b + 1, x)/2
# 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_integrate_derivatives():
assert integrate(Derivative(f(x), x), x) == f(x)
def test_integrate_functions():
# issue sympy/sympy#4111
assert integrate(f(x), x) == Integral(f(x), x)
assert integrate(f(x), (x, 0, 1)) == Integral(f(x), (x, 0, 1))
assert integrate(Derivative(f(y), y), x) == x*Derivative(f(y), y)
def test_diff():
assert O(1).diff(x) == 0
assert O(1, x).diff(x) == Derivative(O(1, x), x)
assert O(x**2).diff(x) == Derivative(O(x**2), x)
def test_im():
a, b = symbols('a,b', extended_real=True)
r = Symbol('r', extended_real=True)
i = Symbol('i', imaginary=True)
assert im(nan) == nan
assert im(oo * I) == oo
assert im(-oo * I) == -oo
assert im(0) == 0
assert im(1) == 0
assert im(-1) == 0
assert im(E * I) == E
assert im(-E * I) == -E
x = Symbol('x')
assert im(x) == im(x)
assert im(x * I) == re(x)
assert im(r * I) == r
assert im(r) == 0
assert im(i * I) == 0
assert im(i) == -I * i
y = Symbol('x')
assert im(x + y) == im(x + y)
assert im(x + r) == im(x)
assert im(x + r * I) == im(x) + r
assert im(im(x) * I) == im(x)
assert im(2 + I) == 1
assert im(x + I) == im(x) + 1
assert im(x + y * I) == im(x) + re(y)
assert im(x + r * I) == im(x) + r
assert im(log(2 * I)) == pi / 2
assert im((2 + I)**2).expand(complex=True) == 4
assert im(conjugate(x)) == -im(x)
assert conjugate(im(x)) == im(x)
assert im(x).as_real_imag() == (im(x), 0)
assert im(i * r * x).diff(r) == im(i * x)
assert im(i * r * x).diff(i) == -I * re(r * x)
assert im(sqrt(a +
b * I)) == root(a**2 + b**2, 4) * sin(arg(a + I * b) / 2)
assert im(a * (2 + b * I)) == a * b
assert im((1 + sqrt(a + b * I)) /
2) == root(a**2 + b**2, 4) * sin(arg(a + I * b) / 2) / 2
assert im(x).rewrite(re) == -I * (x - re(x)) # sympy/sympy#10897
assert (x + im(y)).rewrite(im, re) == x - I * (y - re(y))
a = Symbol('a', algebraic=True)
t = Symbol('t', transcendental=True)
assert re(a).is_algebraic
assert re(x).is_algebraic is None
assert re(t).is_algebraic is False
assert re(zoo) == nan
# issue sympy/sympy#4757
x = Symbol('x', extended_real=True)
y = Symbol('y', imaginary=True)
f = Function('f')
assert im(f(x)).diff(x) == im(f(x).diff(x))
assert im(f(y)).diff(y) == -I * re(f(y).diff(y))
assert im(f(z)).diff(z) == Derivative(im(f(z)), z)
def test_meijer():
pytest.raises(TypeError, lambda: meijerg(1, z))
pytest.raises(TypeError, lambda: meijerg(((1, ), (2, )), (3, ), (4, ), z))
pytest.raises(TypeError, lambda: meijerg((1, 2, 3), (4, 5), z))
assert meijerg(((1, 2), (3,)), ((4,), (5,)), z) == \
meijerg(Tuple(1, 2), Tuple(3), Tuple(4), Tuple(5), z)
g = meijerg((1, 2), (3, 4, 5), (6, 7, 8, 9), (10, 11, 12, 13, 14), z)
assert g.an == Tuple(1, 2)
assert g.ap == Tuple(1, 2, 3, 4, 5)
assert g.aother == Tuple(3, 4, 5)
assert g.bm == Tuple(6, 7, 8, 9)
assert g.bq == Tuple(6, 7, 8, 9, 10, 11, 12, 13, 14)
assert g.bother == Tuple(10, 11, 12, 13, 14)
assert g.argument == z
assert g.nu == 75
assert g.delta == -1
assert g.is_commutative is True
assert meijerg([1, 2], [3], [4], [5], z).delta == Rational(1, 2)
# just a few checks to make sure that all arguments go where they should
assert tn(meijerg(Tuple(), Tuple(), Tuple(0), Tuple(), -z), exp(z), z)
assert tn(
sqrt(pi) *
meijerg(Tuple(), Tuple(), Tuple(0), Tuple(Rational(1, 2)), z**2 / 4),
cos(z), z)
assert tn(meijerg(Tuple(1, 1), Tuple(), Tuple(1), Tuple(0), z), log(1 + z),
z)
# test exceptions
pytest.raises(ValueError, lambda: meijerg(((3, 1), (2, )), ((oo, ),
(2, 0)), x))
pytest.raises(ValueError, lambda: meijerg(((3, 1), (2, )), ((1, ),
(2, 0)), x))
# differentiation
g = meijerg((randcplx(), ), (randcplx() + 2 * I, ), Tuple(),
(randcplx(), randcplx()), z)
assert td(g, z)
g = meijerg(Tuple(), (randcplx(), ), Tuple(), (randcplx(), randcplx()), z)
assert td(g, z)
g = meijerg(Tuple(), Tuple(), Tuple(randcplx()),
Tuple(randcplx(), randcplx()), z)
assert td(g, z)
a1, a2, b1, b2, c1, c2, d1, d2 = symbols('a1:3, b1:3, c1:3, d1:3')
assert meijerg((a1, a2), (b1, b2), (c1, c2), (d1, d2), z).diff(z) == \
(meijerg((a1 - 1, a2), (b1, b2), (c1, c2), (d1, d2), z)
+ (a1 - 1)*meijerg((a1, a2), (b1, b2), (c1, c2), (d1, d2), z))/z
assert meijerg([z, z], [], [], [], z).diff(z) == \
Derivative(meijerg([z, z], [], [], [], z), z)
# meijerg is unbranched wrt parameters
assert meijerg([polar_lift(a1)],
[polar_lift(a2)], [polar_lift(b1)], [polar_lift(b2)],
polar_lift(z)) == meijerg([a1], [a2], [b1], [b2],
polar_lift(z))
# integrand
assert meijerg([a], [b], [c], [d], z).integrand(s) == \
z**s*gamma(c - s)*gamma(-a + s + 1)/(gamma(b - s)*gamma(-d + s + 1))
assert meijerg([[], []], [[Rational(1, 2)], [0]], 1).is_number
assert not meijerg([[], []], [[x], [0]], 1).is_number
def test_re():
a, b = symbols('a,b', extended_real=True)
r = Symbol('r', extended_real=True)
i = Symbol('i', imaginary=True)
assert re(nan) == nan
assert re(oo) == oo
assert re(-oo) == -oo
assert re(0) == 0
assert re(1) == 1
assert re(-1) == -1
assert re(E) == E
assert re(-E) == -E
x = Symbol('x')
assert re(x) == re(x)
assert re(x * I) == -im(x)
assert re(r * I) == 0
assert re(r) == r
assert re(i * I) == I * i
assert re(i) == 0
y = Symbol('y')
assert re(x + y) == re(x + y)
assert re(x + r) == re(x) + r
assert re(re(x)) == re(x)
assert re(2 + I) == 2
assert re(x + I) == re(x)
assert re(x + y * I) == re(x) - im(y)
assert re(x + r * I) == re(x)
assert re(log(2 * I)) == log(2)
assert re((2 + I)**2).expand(complex=True) == 3
assert re(conjugate(x)) == re(x)
assert conjugate(re(x)) == re(x)
assert re(x).as_real_imag() == (re(x), 0)
assert re(i * r * x).diff(r) == re(i * x)
assert re(i * r * x).diff(i) == I * r * im(x)
assert re(sqrt(a +
b * I)) == root(a**2 + b**2, 4) * cos(arg(a + I * b) / 2)
assert re(a * (2 + b * I)) == 2 * a
assert re(
(1 + sqrt(a + b * I)) /
2) == root(a**2 + b**2, 4) * cos(arg(a + I * b) / 2) / 2 + Rational(
1, 2)
assert re(x).rewrite(im) == x - I * im(x) # issue sympy/sympy#10897
assert (x + re(y)).rewrite(re, im) == x + y - I * im(y)
a = Symbol('a', algebraic=True)
t = Symbol('t', transcendental=True)
assert re(a).is_algebraic
assert re(x).is_algebraic is None
assert re(t).is_algebraic is False
assert re(zoo) == nan
# issue sympy/sympy#4757
x = Symbol('x', extended_real=True)
y = Symbol('y', imaginary=True)
f = Function('f')
assert re(f(x)).diff(x) == re(f(x).diff(x))
assert re(f(y)).diff(y) == -I * im(f(y).diff(y))
assert re(f(z)).diff(z) == Derivative(re(f(z)), z)
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_Subs():
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, 0), (y, 1), (z, 1)) != \
Subs(f(x, y, z), (x, 0), (y, 0), (z, 1))
assert Subs(f(x, y), (x, 0), (y, 1), (z, 1)) == \
Subs(f(x, y), (x, 0), (y, 1), (z, 2))
assert Subs(f(x, y), (x, 0), (y, 1), (z, 1)) != \
Subs(f(x, y) + z, (x, 0), (y, 1), (z, 0))
assert Subs(f(x, y), (x, 0), (y, 1)).doit() == f(0, 1)
assert Subs(Subs(f(x, y), (x, 0)), (y, 1)).doit() == f(0, 1)
pytest.raises(ValueError, lambda: Subs(f(x, y), x))
pytest.raises(ValueError, lambda: Subs(f(x, y), (x, 0), (x, 0), (y, 1)))
assert len(Subs(f(x, y), (x, 0), (y, 1)).variables) == 2
assert Subs(f(x, y), (x, 0), (y, 1)).point == Tuple(0, 1)
assert Subs(f(x), (x, 0)) == Subs(f(y), (y, 0))
assert Subs(f(x, y), (x, 0), (y, 1)) == Subs(f(x, y), (y, 1), (x, 0))
assert Subs(f(x) * y, (x, 0), (y, 1)) == Subs(f(y) * x, (y, 0), (x, 1))
assert Subs(f(x) * y, (x, 1), (y, 1)) == Subs(f(y) * x, (x, 1), (y, 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, 0), (y, 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, 0), (y, pi/3)).evalf(2, strict=False) == \
Subs(f(x)*cos(y) + z, (x, 0), (y, pi/3)).evalf(2, strict=False) == \
z + Rational('1/2').evalf(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})
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_requires_partial():
x, y, z, t, nu = symbols('x y z 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_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_count_ops_visual():
ADD, MUL, POW, SIN, COS, EXP, AND, D, G = symbols(
'Add Mul Pow sin cos exp And Derivative Integral'.upper())
DIV, SUB, NEG = symbols('DIV SUB NEG')
NOT, OR, AND, XOR, IMPLIES, EQUIVALENT, _ITE, BASIC, TUPLE = symbols(
'Not Or And Xor Implies Equivalent ITE Basic Tuple'.upper())
def count(val):
return count_ops(val, visual=True)
assert count(7) is S.Zero
assert count(Integer(7)) is S.Zero
assert count(-1) == NEG
assert count(-2) == NEG
assert count(Rational(2, 3)) == DIV
assert count(pi / 3) == DIV
assert count(-pi / 3) == DIV + NEG
assert count(I - 1) == SUB
assert count(1 - I) == SUB
assert count(1 - 2 * I) == SUB + MUL
assert count(x) is S.Zero
assert count(-x) == NEG
assert count(-2 * x / 3) == NEG + DIV + MUL
assert count(1 / x) == DIV
assert count(1 / (x * y)) == DIV + MUL
assert count(-1 / x) == NEG + DIV
assert count(-2 / x) == NEG + DIV
assert count(x / y) == DIV
assert count(-x / y) == NEG + DIV
assert count(x**2) == POW
assert count(-x**2) == POW + NEG
assert count(-2 * x**2) == POW + MUL + NEG
assert count(x + pi / 3) == ADD + DIV
assert count(x + Rational(1, 3)) == ADD + DIV
assert count(x + y) == ADD
assert count(x - y) == SUB
assert count(y - x) == SUB
assert count(-1 / (x - y)) == DIV + NEG + SUB
assert count(-1 / (y - x)) == DIV + NEG + SUB
assert count(1 + x**y) == ADD + POW
assert count(1 + x + y) == 2 * ADD
assert count(1 + x + y + z) == 3 * ADD
assert count(1 + x**y + 2 * x * y + y**2) == 3 * ADD + 2 * POW + 2 * MUL
assert count(2 * z + y + x + 1) == 3 * ADD + MUL
assert count(2 * z + y**17 + x + 1) == 3 * ADD + MUL + POW
assert count(2 * z + y**17 + x + sin(x)) == 3 * ADD + POW + MUL + SIN
assert count(2 * z + y**17 + x +
sin(x**2)) == 3 * ADD + MUL + 2 * POW + SIN
assert count(2 * z + y**17 + x + sin(x**2) +
exp(cos(x))) == 4 * ADD + MUL + 3 * POW + COS + SIN
assert count(Derivative(x, x)) == D
assert count(Integral(x, x) + 2 * x / (1 + x)) == G + DIV + MUL + 2 * ADD
assert count(Basic()) is S.Zero
assert count({x + 1: sin(x)}) == ADD + SIN
assert count([x + 1, sin(x) + y, None]) == ADD + SIN + ADD
assert count({x + 1: sin(x), y: cos(x) + 1}) == SIN + COS + 2 * ADD
assert count({}) is S.Zero
assert count([x + 1, sin(x) * y, None]) == SIN + ADD + MUL
assert count([]) is S.Zero
assert count(Basic()) == 0
assert count(Basic(Basic(), Basic(x, x + y))) == ADD + 2 * BASIC
assert count(Basic(x, x + y)) == ADD + BASIC
assert count(Or(x, y)) == OR
assert count(And(x, y)) == AND
assert count(And(x**y, z)) == AND + POW
assert count(Or(x, Or(y, And(z, a)))) == AND + OR
assert count(Nor(x, y)) == NOT + OR
assert count(Nand(x, y)) == NOT + AND
assert count(Xor(x, y)) == XOR
assert count(Implies(x, y)) == IMPLIES
assert count(Equivalent(x, y)) == EQUIVALENT
assert count(ITE(x, y, z)) == _ITE
assert count([Or(x, y), And(x, y), Basic(x + y)]) == ADD + AND + BASIC + OR
assert count(Basic(Tuple(x))) == BASIC + TUPLE
# It checks that TUPLE is counted as an operation.
assert count(Eq(x + y, Integer(2))) == ADD
