def test_literal_evalf_is_number_is_zero_is_comparable():
from sympy.integrals.integrals import Integral
from sympy.core.symbol import symbols
from sympy.core.function import Function
from sympy.functions.elementary.trigonometric import cos, sin
x = symbols('x')
f = Function('f')
# issue 5033
assert f.is_number is False
# issue 6646
assert f(1).is_number is False
i = Integral(0, (x, x, x))
# expressions that are symbolically 0 can be difficult to prove
# so in case there is some easy way to know if something is 0
# it should appear in the is_zero property for that object;
# if is_zero is true evalf should always be able to compute that
# zero
assert i.n() == 0
assert i.is_zero
assert i.is_number is False
assert i.evalf(2, strict=False) == 0
# issue 10268
n = sin(1)**2 + cos(1)**2 - 1
assert n.is_comparable is False
assert n.n(2).is_comparable is False
assert n.n(2).n(2).is_comparable
def test_as_sum_raises():
e = Integral((x + y)**2, (x, 0, 1))
raises(ValueError, lambda: e.as_sum(-1))
raises(ValueError, lambda: e.as_sum(0))
raises(ValueError, lambda: Integral(x).as_sum(3))
raises(NotImplementedError, lambda: e.as_sum(oo))
raises(NotImplementedError, lambda: e.as_sum(3, method='xxxx2'))
def test_expand_integral():
assert Integral(cos(x ** 2) * (sin(x ** 2) + 1), (x, 0, 1)).expand() == Integral(
cos(x ** 2) * sin(x ** 2) + cos(x ** 2), (x, 0, 1)
)
assert Integral(cos(x ** 2) * (sin(x ** 2) + 1), x).expand() == Integral(cos(x ** 2) * sin(x ** 2) + cos(x ** 2), x)
i = Integral(x, (x, 1, 2), (x, 1, 2))
assert i._eval_expand_basic() == i
def test_as_sum_right():
e = Integral((x + y)**2, (x, 0, 1))
assert e.as_sum(1, method="right").expand() == 1 + 2*y + y**2
assert e.as_sum(2, method="right").expand() == S(5)/8 + 3*y/2 + y**2
assert e.as_sum(3, method="right").expand() == S(14)/27 + 4*y/3 + y**2
assert e.as_sum(4, method="right").expand() == S(15)/32 + 5*y/4 + y**2
assert e.as_sum(n, method="right").expand() == \
y**2 + y + S(1)/3 + y/n + 1/(2*n) + 1/(6*n**2)
def test_subs7():
e = Integral(x, (x, 1, y), (y, 1, 2))
assert e.subs({x: 1, y: 2}) == e
e = Integral(sin(x) + sin(y), (x, sin(x), sin(y)),
(y, 1, 2))
assert e.subs(sin(y), 1) == e
assert e.subs(sin(x), 1) == Integral(sin(x) + sin(y), (x, 1, sin(y)),
(y, 1, 2))
def test_doit():
e = Integral(Integral(2*x), (x, 0, 1))
assert e.doit() == Rational(1, 3)
f = Function('f')
# doesn't matter if the integral can't be performed
assert Integral(f(x), (x, 1, 1)).doit() == 0
# doesn't matter if the limits can't be evaluated
assert Integral(0, (x, 1, Integral(f(x), x))).doit() == 0
def test_issue1566():
# Allow only upper or lower limit evaluation
e = Integral(x**2, (x, None, 1))
f = Integral(x**2, (x, 1, None))
assert e.doit() == Rational(1, 3)
assert f.doit() == Rational(-1, 3)
assert Integral(x*y, (x, None, y)).subs(y, t) == Integral(x*t, (x, None, t))
assert Integral(x*y, (x, y, None)).subs(y, t) == Integral(x*t, (x, t, None))
def test_as_sum_trapezoid():
e = Integral((x + y)**2, (x, 0, 1))
assert e.as_sum(1, method="trapezoid").expand() == y**2 + y + S(1)/2
assert e.as_sum(2, method="trapezoid").expand() == y**2 + y + S(3)/8
assert e.as_sum(3, method="trapezoid").expand() == y**2 + y + S(19)/54
assert e.as_sum(4, method="trapezoid").expand() == y**2 + y + S(11)/32
assert e.as_sum(n, method="trapezoid").expand() == \
y**2 + y + S(1)/3 + 1/(6*n**2)
assert Integral(sign(x), (x, 0, 1)).as_sum(1, 'trapezoid') == S(1)/2
def test_as_sum_midpoint2():
e = Integral((x + y)**2, (x, 0, 1))
n = Symbol('n', positive=True, integer=True)
assert e.as_sum(1, method="midpoint").expand() == S(1)/4 + y + y**2
assert e.as_sum(2, method="midpoint").expand() == S(5)/16 + y + y**2
assert e.as_sum(3, method="midpoint").expand() == S(35)/108 + y + y**2
assert e.as_sum(4, method="midpoint").expand() == S(21)/64 + y + y**2
assert e.as_sum(n, method="midpoint").expand() == \
y**2 + y + 1/3 - 1/(12*n**2)
def test_doit():
a = Integral(x**2, x)
assert isinstance(a.doit(), Integral) == False
assert isinstance(a.doit(integrals=True), Integral) == False
assert isinstance(a.doit(integrals=False), Integral) == True
assert (2*Integral(x, x)).doit() == x**2
def test_as_sum_left():
e = Integral((x + y)**2, (x, 0, 1))
assert e.as_sum(1, method="left").expand() == y**2
assert e.as_sum(2, method="left").expand() == S(1)/8 + y/2 + y**2
assert e.as_sum(3, method="left").expand() == S(5)/27 + 2*y/3 + y**2
assert e.as_sum(4, method="left").expand() == S(7)/32 + 3*y/4 + y**2
assert e.as_sum(n, method="left").expand() == \
y**2 + y + S(1)/3 - y/n - 1/(2*n) + 1/(6*n**2)
assert e.as_sum(10, method="left", evaluate=False).has(Sum)
def test_is_zero():
from sympy.abc import x, m, n
assert Integral(0, (x, 1, x)).is_zero
assert Integral(1, (x, 1, 1)).is_zero
assert Integral(1, (x, 1, 2)).is_zero is False
assert Integral(sin(m*x)*cos(n*x), (x, 0, 2*pi)).is_zero is None
assert Integral(x, (m, 0)).is_zero
assert Integral(x + 1/m, (m, 0)).is_zero is None
i = Integral(m, (m, 1, exp(x)), (x, 0))
assert i.is_zero is None and i.doit() == S(1)/4
assert Integral(m, (x, 0), (m, 1, exp(x))).is_zero is True
def test_doit_integrals():
e = Integral(Integral(2*x), (x, 0, 1))
assert e.doit() == Rational(1, 3)
assert e.doit(deep=False) == Rational(1, 3)
f = Function('f')
# doesn't matter if the integral can't be performed
assert Integral(f(x), (x, 1, 1)).doit() == 0
# doesn't matter if the limits can't be evaluated
assert Integral(0, (x, 1, Integral(f(x), x))).doit() == 0
assert Integral(x, (a, 0)).doit() == 0
limits = ((a, 1, exp(x)), (x, 0))
assert Integral(a, *limits).doit() == S(1)/4
assert Integral(a, *list(reversed(limits))).doit() == 0
def test_issue1566():
# Allow only upper or lower limit evaluation
e = Integral(x**2, (x, None, 1))
f = Integral(x**2, (x, 1, None))
assert e.doit() == Rational(1, 3)
assert f.doit() == Rational(-1, 3)
assert Integral(x*y, (x, None, y)).subs(y, t) == Integral(x*t, (x, None, t))
assert Integral(x*y, (x, y, None)).subs(y, t) == Integral(x*t, (x, t, None))
#FIXME-py3k: This fails somewhere down the line with:
#FIXME-py3k: TypeError: type Float doesn't define __round__ method
assert integrate(x**2, (x, None, 1)) == Rational(1, 3)
assert integrate(x**2, (x, 1, None)) == Rational(-1, 3)
assert integrate("x**2", ("x", "1", None)) == Rational(-1, 3)
def test_get_motion_methods():
# Initialization
t = dynamicsymbols._t
s1, s2, s3 = symbols("s1 s2 s3")
S1, S2, S3 = symbols("S1 S2 S3")
S4, S5, S6 = symbols("S4 S5 S6")
t1, t2 = symbols("t1 t2")
a, b, c = dynamicsymbols("a b c")
ad, bd, cd = dynamicsymbols("a b c", 1)
a2d, b2d, c2d = dynamicsymbols("a b c", 2)
v0 = S1 * N.x + S2 * N.y + S3 * N.z
v01 = S4 * N.x + S5 * N.y + S6 * N.z
v1 = s1 * N.x + s2 * N.y + s3 * N.z
v2 = a * N.x + b * N.y + c * N.z
v2d = ad * N.x + bd * N.y + cd * N.z
v2dd = a2d * N.x + b2d * N.y + c2d * N.z
# Test position parameter
assert get_motion_params(frame=N) == (0, 0, 0)
assert get_motion_params(N, position=v1) == (0, 0, v1)
assert get_motion_params(N, position=v2) == (v2dd, v2d, v2)
# Test velocity parameter
assert get_motion_params(N, velocity=v1) == (0, v1, v1 * t)
assert get_motion_params(N, velocity=v1, position=v0, timevalue1=t1) == (0, v1, v0 + v1 * (t - t1))
assert get_motion_params(N, velocity=v1, position=v2, timevalue1=t1) == (0, v1, v1 * t - v1 * t1 + v2.subs(t, t1))
integral_vector = Integral(a, t) * N.x + Integral(b, t) * N.y + Integral(c, t) * N.z
assert get_motion_params(N, velocity=v2, position=v0, timevalue1=t1) == (
v2d,
v2,
v0 + integral_vector - integral_vector.subs(t, t1),
)
# Test acceleration parameter
assert get_motion_params(N, acceleration=v1) == (v1, v1 * t, v1 * t ** 2 / 2)
assert get_motion_params(N, acceleration=v1, velocity=v0, position=v2, timevalue1=t1, timevalue2=t2) == (
v1,
(v0 + v1 * t - v1 * t2),
-v0 * t1 + v1 * t ** 2 / 2 + v1 * t2 * t1 - v1 * t1 ** 2 / 2 + t * (v0 - v1 * t2) + v2.subs(t, t1),
)
assert get_motion_params(N, acceleration=v1, velocity=v0, position=v01, timevalue1=t1, timevalue2=t2) == (
v1,
v0 + v1 * t - v1 * t2,
-v0 * t1 + v01 + v1 * t ** 2 / 2 + v1 * t2 * t1 - v1 * t1 ** 2 / 2 + t * (v0 - v1 * t2),
)
i = Integral(a, t)
i_sub = i.subs(t, t2)
assert get_motion_params(
N, acceleration=a * N.x, velocity=S1 * N.x, position=S2 * N.x, timevalue1=t1, timevalue2=t2
) == (
a * N.x,
(S1 + i - i_sub) * N.x,
(S2 + Integral(S1 - t * (a.subs(t, t2)) + i, t) - Integral(S1 - t1 * (a.subs(t, t2)) + i.subs(t, t1), t)) * N.x,
)
def test_transform():
a = Integral(x**2+1, (x, -1, 2))
assert a.doit() == a.transform(x, 3*x+1).doit()
assert a.transform(x, 3*x+1).transform(x, 3*x+1, inverse=True) == a
assert a.transform(x, 3*x+1, inverse=True).transform(x, 3*x+1) == a
a = Integral(sin(1/x), (x, 0, 1))
assert a.transform(x, 1/x) == Integral(sin(x)/x**2, (x, 1, oo))
assert a.transform(x, 1/x).transform(x, 1/x) == a
a = Integral(exp(-x**2), (x, -oo, oo))
assert a.transform(x, 2*x) == Integral(2*exp(-4*x**2), (x, -oo, oo))
raises(ValueError, "a.transform(x, 1/x)")
raises(ValueError, "a.transform(x, 1/x)")
def test_subs5():
e = Integral(exp(-x**2), x)
assert e.subs(x, 5) == e
e = Integral(exp(-x**2), (x, -oo, oo))
assert e.subs(x, 5) == e
e = Integral(exp(-x**2+y), x)
assert e.subs(x, 5) == e
assert e.subs(y, 5) != e
assert e.subs(y, 5) == Integral(exp(-x**2+5), x)
e = Integral(exp(-x**2+y), (y, -oo, oo), (x, -oo, oo))
assert e.subs(x, 5) == e
assert e.subs(y, 5) == e
def __new__(cls, function, *limits, **assumptions):
repl, limits = IndexedIntegral._indexed_process_limits(limits)
function = sympify(function)
function = function.xreplace(repl)
obj = Integral.__new__(cls, function, *limits, **assumptions)
obj._indexed_repl = repl
obj._indexed_reverse_repl = dict((val, key) for key, val in repl.items())
return obj
def test_transform():
a = Integral(x ** 2 + 1, (x, -1, 2))
fx = x
fy = 3 * y + 1
assert a.doit() == a.transform(fx, fy).doit()
assert a.transform(fx, fy).transform(fy, fx) == a
fx = 3 * x + 1
fy = y
assert a.transform(fx, fy).transform(fy, fx) == a
a = Integral(sin(1 / x), (x, 0, 1))
assert a.transform(x, 1 / y) == Integral(sin(y) / y ** 2, (y, 1, oo))
assert a.transform(x, 1 / y).transform(y, 1 / x) == a
a = Integral(exp(-x ** 2), (x, -oo, oo))
assert a.transform(x, 2 * y) == Integral(2 * exp(-4 * y ** 2), (y, -oo, oo))
# < 3 arg limit handled properly
assert Integral(x, x).transform(x, a * y).doit() == Integral(y * a ** 2, y).doit()
_3 = S(3)
assert Integral(x, (x, 0, -_3)).transform(x, 1 / y).doit() == Integral(-1 / x ** 3, (x, -oo, -1 / _3)).doit()
assert Integral(x, (x, 0, _3)).transform(x, 1 / y) == Integral(y ** (-3), (y, 1 / _3, oo))
def test_as_sum_midpoint1():
e = Integral(sqrt(x**3 + 1), (x, 2, 10))
assert e.as_sum(1, method="midpoint") == 8*sqrt(217)
assert e.as_sum(2, method="midpoint") == 4*sqrt(65) + 12*sqrt(57)
assert e.as_sum(3, method="midpoint") == 8*sqrt(217)/3 + \
8*sqrt(3081)/27 + 8*sqrt(52809)/27
assert e.as_sum(4, method="midpoint") == 2*sqrt(730) + \
4*sqrt(7) + 4*sqrt(86) + 6*sqrt(14)
assert abs(e.as_sum(4, method="midpoint").n() - e.n()) < 0.5
e = Integral(sqrt(x**3 + y**3), (x, 2, 10), (y, 0, 10))
raises(NotImplementedError, lambda: e.as_sum(4))
def test_transform():
a = Integral(x ** 2 + 1, (x, -1, 2))
assert a.doit() == a.transform(x, 3 * x + 1).doit()
assert a.transform(x, 3 * x + 1).transform(x, 3 * x + 1, inverse=True) == a
assert a.transform(x, 3 * x + 1, inverse=True).transform(x, 3 * x + 1) == a
a = Integral(sin(1 / x), (x, 0, 1))
assert a.transform(x, 1 / x) == Integral(sin(x) / x ** 2, (x, 1, oo))
assert a.transform(x, 1 / x).transform(x, 1 / x) == a
a = Integral(exp(-x ** 2), (x, -oo, oo))
assert a.transform(x, 2 * x) == Integral(2 * exp(-4 * x ** 2), (x, -oo, oo))
# < 3 arg limit handled properly
assert Integral(x, x).transform(x, a * x) == Integral(x * a ** 2, x)
raises(ValueError, "a.transform(x, 1/x)")
raises(ValueError, "a.transform(x, 1/x)")
_3 = S(3)
assert Integral(x, (x, 0, -_3)).transform(x, 1 / x) == Integral(-1 / x ** 3, (x, -oo, -1 / _3))
assert Integral(x, (x, 0, _3)).transform(x, 1 / x) == Integral(x ** (-3), (x, 1 / _3, oo))
def test_is_number():
from sympy.abc import x, y, z
from sympy import cos, sin
assert Integral(x).is_number is False
assert Integral(1, x).is_number is False
assert Integral(1, (x, 1)).is_number is True
assert Integral(1, (x, 1, 2)).is_number is True
assert Integral(1, (x, 1, y)).is_number is False
assert Integral(1, (x, y)).is_number is False
assert Integral(x, y).is_number is False
assert Integral(x, (y, 1, x)).is_number is False
assert Integral(x, (y, 1, 2)).is_number is False
assert Integral(x, (x, 1, 2)).is_number is True
i = Integral(x, (y, 1, 1))
assert i.is_number is True and i.n() == 0
i = Integral(x, (y, z, z))
assert i.is_number is True and i.n() == 0
i = Integral(1, (y, z, z + 2))
assert i.is_number is True and i.n() == 2
assert Integral(x*y, (x, 1, 2), (y, 1, 3)).is_number is True
assert Integral(x*y, (x, 1, 2), (y, 1, z)).is_number is False
assert Integral(x, (x, 1)).is_number is True
assert Integral(x, (x, 1, Integral(y, (y, 1, 2)))).is_number is True
assert Integral(Sum(z, (z, 1, 2)), (x, 1, 2)).is_number is True
# it is possible to get a false negative if the integrand is
# actually an unsimplified zero, but this is true of is_number in general.
assert Integral(sin(x)**2 + cos(x)**2 - 1, x).is_number is False
assert Integral(f(x), (x, 0, 1)).is_number is True
def test_is_number():
from sympy.abc import x, y, z
from sympy import cos, sin
assert Integral(x).is_number is False
assert Integral(1, x).is_number is False
assert Integral(1, (x, 1)).is_number is True
assert Integral(1, (x, 1, 2)).is_number is True
assert Integral(1, (x, 1, y)).is_number is False
assert Integral(1, (x, y)).is_number is False
assert Integral(x, y).is_number is False
assert Integral(x, (y, 1, x)).is_number is False
assert Integral(x, (y, 1, 2)).is_number is False
assert Integral(x, (x, 1, 2)).is_number is True
# `foo.is_number` should always be eqivalent to `not foo.free_symbols`
# in each of these cases, there are pseudo-free symbols
i = Integral(x, (y, 1, 1))
assert i.is_number is False and i.n() == 0
i = Integral(x, (y, z, z))
assert i.is_number is False and i.n() == 0
i = Integral(1, (y, z, z + 2))
assert i.is_number is False and i.n() == 2
assert Integral(x*y, (x, 1, 2), (y, 1, 3)).is_number is True
assert Integral(x*y, (x, 1, 2), (y, 1, z)).is_number is False
assert Integral(x, (x, 1)).is_number is True
assert Integral(x, (x, 1, Integral(y, (y, 1, 2)))).is_number is True
assert Integral(Sum(z, (z, 1, 2)), (x, 1, 2)).is_number is True
# it is possible to get a false negative if the integrand is
# actually an unsimplified zero, but this is true of is_number in general.
assert Integral(sin(x)**2 + cos(x)**2 - 1, x).is_number is False
assert Integral(f(x), (x, 0, 1)).is_number is True
def test_subs2():
e = Integral(exp(x - y), x, t)
assert e.subs(y, 3) == Integral(exp(x - 3), x, t)
e = Integral(exp(x - y), (x, 0, 1), (t, 0, 1))
assert e.subs(y, 3) == Integral(exp(x - 3), (x, 0, 1), (t, 0, 1))
f = Lambda(x, exp(-x**2))
conv = Integral(f(x - y)*f(y), (y, -oo, oo), (t, 0, 1))
assert conv.subs({x: 0}) == Integral(exp(-2*y**2), (y, -oo, oo), (t, 0, 1))
def test_as_sum_midpoint1():
e = Integral(sqrt(x**3+1), (x, 2, 10))
assert e.as_sum(1, method="midpoint") == 8*217**(S(1)/2)
assert e.as_sum(2, method="midpoint") == 4*65**(S(1)/2) + 12*57**(S(1)/2)
assert e.as_sum(3, method="midpoint") == 8*217**(S(1)/2)/3 + \
8*3081**(S(1)/2)/27 + 8*52809**(S(1)/2)/27
assert e.as_sum(4, method="midpoint") == 2*730**(S(1)/2) + \
4*7**(S(1)/2) + 4*86**(S(1)/2) + 6*14**(S(1)/2)
assert abs(e.as_sum(4, method="midpoint").n() - e.n()) < 0.5
e = Integral(sqrt(x**3+y**3), (x, 2, 10), (y, 0, 10))
raises(NotImplementedError, "e.as_sum(4)")
def test_has_integrals():
f = Integral(x**2 + sin(x*y*z), (x, 0, x + y + z))
assert f.has(x + y)
assert f.has(x + z)
assert f.has(y + z)
assert f.has(x*y)
assert f.has(x*z)
assert f.has(y*z)
assert not f.has(2*x + y)
assert not f.has(2*x*y)
def test_subs6():
a, b = symbols('a b')
e = Integral(x*y, (x, f(x), f(y)))
assert e.subs(x, 1) == Integral(x*y, (x, f(1), f(y)))
assert e.subs(y, 1) == Integral(x, (x, f(x), f(1)))
e = Integral(x*y, (x, f(x), f(y)), (y, f(x), f(y)))
assert e.subs(x, 1) == Integral(x*y, (x, f(1), f(y)), (y, f(1), f(y)))
assert e.subs(y, 1) == Integral(x*y, (x, f(x), f(y)), (y, f(x), f(1)))
e = Integral(x*y, (x, f(x), f(a)), (y, f(x), f(a)))
assert e.subs(a, 1) == Integral(x*y, (x, f(x), f(1)), (y, f(x), f(1)))
def main():
print "Hydrogen radial wavefunctions:"
var("r a")
print "R_{21}:"
pprint(R_nl(2, 1, a, r))
print "R_{60}:"
pprint(R_nl(6, 0, a, r))
print "Normalization:"
i = Integral(R_nl(1, 0, 1, r)**2 * r**2, (r, 0, oo))
print pretty(i), " = ", i.doit()
i = Integral(R_nl(2, 0, 1, r)**2 * r**2, (r, 0, oo))
print pretty(i), " = ", i.doit()
i = Integral(R_nl(2, 1, 1, r)**2 * r**2, (r, 0, oo))
print pretty(i), " = ", i.doit()
def main():
print "Hydrogen radial wavefunctions:"
a, r = symbols("a r")
print "R_{21}:"
pprint(R_nl(2, 1, a, r))
print "R_{60}:"
pprint(R_nl(6, 0, a, r))
print "Normalization:"
i = Integral(R_nl(1, 0, 1, r)**2 * r**2, (r, 0, oo))
pprint(Eq(i, i.doit()))
i = Integral(R_nl(2, 0, 1, r)**2 * r**2, (r, 0, oo))
pprint(Eq(i, i.doit()))
i = Integral(R_nl(2, 1, 1, r)**2 * r**2, (r, 0, oo))
pprint(Eq(i, i.doit()))
def test_issue_3679():
# definite integration of rational functions gives wrong answers
assert NS(Integral(1 / (x**2 - 8 * x + 17),
(x, 2, 4))) == '1.10714871779409'
def test_expand():
e = Integral(f(x)+f(x**2), (x, 1, y))
assert e.expand() == Integral(f(x), (x, 1, y)) + Integral(f(x**2), (x, 1, y))
def test_as_sum_midpoint2():
e = Integral((x + y)**2, (x, 0, 1))
assert e.as_sum(1, method="midpoint").expand() == S(1)/4 + y + y**2
assert e.as_sum(2, method="midpoint").expand() == S(5)/16 + y + y**2
assert e.as_sum(3, method="midpoint").expand() == S(35)/108 + y + y**2
assert e.as_sum(4, method="midpoint").expand() == S(21)/64 + y + y**2
def test_as_sum_right():
e = Integral((x + y)**2, (x, 0, 1))
assert e.as_sum(1, method="right").expand() == 1 + 2*y + y**2
assert e.as_sum(2, method="right").expand() == S(5)/8 + 3*y/2 + y**2
assert e.as_sum(3, method="right").expand() == S(14)/27 + 4*y/3 + y**2
assert e.as_sum(4, method="right").expand() == S(15)/32 + 5*y/4 + y**2
def test_integral_reconstruct():
e = Integral(x**2, (x, -1, 1))
assert e == Integral(*e.args)
def test_symbols():
from sympy.abc import x, y, z
assert Integral(0, x).free_symbols == set()
assert Integral(x).free_symbols == set([x])
assert Integral(x, (x, None, y)).free_symbols == set([y])
assert Integral(x, (x, y, None)).free_symbols == set([y])
assert Integral(x, (x, 1, y)).free_symbols == set([y])
assert Integral(x, (x, y, 1)).free_symbols == set([y])
assert Integral(x, (x, x, y)).free_symbols == set([x, y])
assert Integral(x, x, y).free_symbols == set([x, y])
assert Integral(x, (x, 1, 2)).free_symbols == set()
assert Integral(x, (y, 1, 2)).free_symbols == set([x])
assert Integral(x, (y, z, z)).free_symbols == set()
assert Integral(x, (y, 1, 2), (y, None, None)).free_symbols == set([x, y])
assert Integral(x, (y, 1, 2), (x, 1, y)).free_symbols == set([y])
assert Integral(2, (y, 1, 2), (y, 1, x), (x, 1, 2)).free_symbols == set()
assert Integral(2, (y, x, 2), (y, 1, x), (x, 1, 2)).free_symbols == set()
assert Integral(2, (x, 1, 2), (y, x, 2), (y, 1, 2)).free_symbols == \
set([x])
def test_series():
from sympy.abc import x
i = Integral(cos(x), (x, x))
e = i.lseries(x)
assert i.nseries(x, n=8).removeO() == Add(*[next(e) for j in range(4)])
def test_doit():
p1 = Piecewise((x, x < 1), (x**2, -1 <= x), (x, 3 < x))
p2 = Piecewise((x, x < 1), (Integral(2 * x), -1 <= x), (x, 3 < x))
assert p2.doit() == p1
assert p2.doit(deep=False) == p2
def test_doit():
f = Integral(2 * x, x)
l = Limit(f, x, oo)
assert l.doit() == oo
def test_doit2():
f = Integral(2 * x, x)
l = Limit(f, x, oo)
# limit() breaks on the contained Integral.
assert l.doit(deep=False) == l
def test_order_symbols():
e = x * y * sin(x) * Integral(x, (x, 1, 2))
assert O(e) == O(x**2 * y, x, y)
assert O(e, x) == O(x**2)
def test_subs2():
e = Integral(exp(x - y), x, t)
assert e.subs(y, 3) == Integral(exp(x - 3), x, t)
e = Integral(exp(x - y), (x, 0, 1), (t, 0, 1))
assert e.subs(y, 3) == Integral(exp(x - 3), (x, 0, 1), (t, 0, 1))
f = Lambda(x, exp(-x**2))
conv = Integral(f(x - y) * f(y), (y, -oo, oo), (t, 0, 1))
assert conv.subs({x: 0}) == Integral(exp(-2 * y**2), (y, -oo, oo),
(t, 0, 1))
def test_basics():
assert Integral(0, x) != 0
assert Integral(x, (x, 1, 1)) != 0
assert Integral(oo, x) != oo
assert Integral(S.NaN, x) == S.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() == set([x])
assert Integral(f(x), (x, 0, 1)).atoms() == set([S(0), S(1), x])
assert diff_test(Integral(x, (x, 3 * y))) == set([y])
assert diff_test(Integral(x, (a, 3 * y))) == set([x, y])
# 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
def test_conjugate_transpose():
A, B = symbols("A B", commutative=False)
x = Symbol("x", complex=True)
p = Integral(A * B, (x, ))
assert p.adjoint().doit() == p.doit().adjoint()
assert p.conjugate().doit() == p.doit().conjugate()
assert p.transpose().doit() == p.doit().transpose()
x = Symbol("x", real=True)
p = Integral(A * B, (x, ))
assert p.adjoint().doit() == p.doit().adjoint()
assert p.conjugate().doit() == p.doit().conjugate()
assert p.transpose().doit() == p.doit().transpose()
def test_issue_1100():
ypos = Symbol('y', positive=True)
# TODO: Remove conds='none' below, let the assumption take care of it.
assert integrate(exp(-I*2*pi*ypos*x)*x, (x, -oo, oo), conds='none') == \
Integral(exp(-I*2*pi*ypos*x)*x, (x, -oo, oo))
def test_issue2068():
from sympy.abc import w, x, y, z
f = Function('f')
assert Integral(Integral(f(x), x), x) == Integral(f(x), x, x)
assert Integral(f(x)).args == (f(x), Tuple(x))
assert Integral(Integral(f(x))).args == (f(x), Tuple(x), Tuple(x))
assert Integral(Integral(f(x)), y).args == (f(x), Tuple(x), Tuple(y))
assert Integral(Integral(f(x), z), y).args == (f(x), Tuple(z), Tuple(y))
assert Integral(Integral(Integral(f(x), x), y), z).args == \
(f(x), Tuple(x), Tuple(y), Tuple(z))
assert integrate(Integral(f(x), x), x) == Integral(f(x), x, x)
assert integrate(Integral(f(x), y), x) == Integral(y*f(x), x)
assert integrate(Integral(f(x), x), y) == Integral(y*f(x), x)
assert integrate(Integral(2, x), x) == x**2
assert integrate(Integral(2, x), y) == 2*x*y
# don't re-order given limits
assert Integral(1, x, y).args != Integral(1, y, x).args
# do as many as possibble
assert Integral(f(x), y, x, y, x).doit() == Integral(y**2*f(x)/2, x, x)
assert Integral(f(x), (x, 1, 2), (w, 1, x), (z, 1, y)).doit() == \
Integral(-f(x) + y*f(x), (x, 1, 2), (w, 1, x))
def test_piecewise():
# Test canonicalization
assert Piecewise((x, x < 1), (0, True)) == Piecewise((x, x < 1), (0, True))
assert Piecewise((x, x < 1), (0, True), (1, True)) == \
Piecewise((x, x < 1), (0, True))
assert Piecewise((x, x < 1), (0, False), (-1, 1 > 2)) == \
Piecewise((x, x < 1))
assert Piecewise((x, x < 1), (0, x < 1), (0, True)) == \
Piecewise((x, x < 1), (0, True))
assert Piecewise((x, x < 1), (0, x < 2), (0, True)) == \
Piecewise((x, x < 1), (0, True))
assert Piecewise((x, x < 1), (x, x < 2), (0, True)) == \
Piecewise((x, Or(x < 1, x < 2)), (0, True))
assert Piecewise((x, x < 1), (x, x < 2), (x, True)) == x
assert Piecewise((x, True)) == x
# False condition is never retained
assert Piecewise((x, False)) == Piecewise(
(x, False), evaluate=False) == Piecewise()
raises(TypeError, lambda: Piecewise(x))
assert Piecewise((x, 1)) == x # 1 and 0 are accepted as True/False
raises(TypeError, lambda: Piecewise((x, 2)))
raises(TypeError, lambda: Piecewise((x, x**2)))
raises(TypeError, lambda: Piecewise(([1], True)))
assert Piecewise(((1, 2), True)) == Tuple(1, 2)
cond = (Piecewise((1, x < 0), (2, True)) < y)
assert Piecewise((1, cond)) == Piecewise((1, ITE(x < 0, y > 1, y > 2)))
assert Piecewise((1, x > 0), (2, And(x <= 0, x > -1))) == Piecewise(
(1, x > 0), (2, x > -1))
# Test subs
p = Piecewise((-1, x < -1), (x**2, x < 0), (log(x), x >= 0))
p_x2 = Piecewise((-1, x**2 < -1), (x**4, x**2 < 0), (log(x**2), x**2 >= 0))
assert p.subs(x, x**2) == p_x2
assert p.subs(x, -5) == -1
assert p.subs(x, -1) == 1
assert p.subs(x, 1) == log(1)
# More subs tests
p2 = Piecewise((1, x < pi), (-1, x < 2 * pi), (0, x > 2 * pi))
p3 = Piecewise((1, Eq(x, 0)), (1 / x, True))
p4 = Piecewise((1, Eq(x, 0)), (2, 1 / x > 2))
assert p2.subs(x, 2) == 1
assert p2.subs(x, 4) == -1
assert p2.subs(x, 10) == 0
assert p3.subs(x, 0.0) == 1
assert p4.subs(x, 0.0) == 1
f, g, h = symbols('f,g,h', cls=Function)
pf = Piecewise((f(x), x < -1), (f(x) + h(x) + 2, x <= 1))
pg = Piecewise((g(x), x < -1), (g(x) + h(x) + 2, x <= 1))
assert pg.subs(g, f) == pf
assert Piecewise((1, Eq(x, 0)), (0, True)).subs(x, 0) == 1
assert Piecewise((1, Eq(x, 0)), (0, True)).subs(x, 1) == 0
assert Piecewise((1, Eq(x, y)), (0, True)).subs(x, y) == 1
assert Piecewise((1, Eq(x, z)), (0, True)).subs(x, z) == 1
assert Piecewise((1, Eq(exp(x), cos(z))), (0, True)).subs(x, z) == \
Piecewise((1, Eq(exp(z), cos(z))), (0, True))
p5 = Piecewise((0, Eq(cos(x) + y, 0)), (1, True))
assert p5.subs(y, 0) == Piecewise((0, Eq(cos(x), 0)), (1, True))
assert Piecewise((-1, y < 1), (0, x < 0), (1, Eq(x, 0)),
(2, True)).subs(x, 1) == Piecewise((-1, y < 1), (2, True))
assert Piecewise((1, Eq(x**2, -1)), (2, x < 0)).subs(x, I) == 1
# Test evalf
assert p.evalf() == p
assert p.evalf(subs={x: -2}) == -1
assert p.evalf(subs={x: -1}) == 1
assert p.evalf(subs={x: 1}) == log(1)
# Test doit
f_int = Piecewise((Integral(x, (x, 0, 1)), x < 1))
assert f_int.doit() == Piecewise((1 / 2, x < 1))
# Test differentiation
f = x
fp = x * p
dp = Piecewise((0, x < -1), (2 * x, x < 0), (1 / x, x >= 0))
fp_dx = x * dp + p
assert diff(p, x) == dp
assert diff(f * p, x) == fp_dx
# Test simple arithmetic
assert x * p == fp
assert x * p + p == p + x * p
assert p + f == f + p
assert p + dp == dp + p
assert p - dp == -(dp - p)
# Test power
dp2 = Piecewise((0, x < -1), (4 * x**2, x < 0), (1 / x**2, x >= 0))
assert dp**2 == dp2
# Test _eval_interval
f1 = x * y + 2
f2 = x * y**2 + 3
peval = Piecewise((f1, x < 0), (f2, x > 0))
peval_interval = f1.subs(x, 0) - f1.subs(x, -1) + f2.subs(x, 1) - f2.subs(
x, 0)
assert peval._eval_interval(x, 0, 0) == 0
assert peval._eval_interval(x, -1, 1) == peval_interval
peval2 = Piecewise((f1, x < 0), (f2, True))
assert peval2._eval_interval(x, 0, 0) == 0
assert peval2._eval_interval(x, 1, -1) == -peval_interval
assert peval2._eval_interval(x, -1, -2) == f1.subs(x, -2) - f1.subs(x, -1)
assert peval2._eval_interval(x, -1, 1) == peval_interval
assert peval2._eval_interval(x, None, 0) == peval2.subs(x, 0)
assert peval2._eval_interval(x, -1, None) == -peval2.subs(x, -1)
# Test integration
assert p.integrate() == Piecewise((-x, x < -1), (x**3 / 3 + 4 / 3, x < 0),
(x * log(x) - x + 4 / 3, True))
p = Piecewise((x, x < 1), (x**2, -1 <= x), (x, 3 < x))
assert integrate(p, (x, -2, 2)) == 5 / 6.0
assert integrate(p, (x, 2, -2)) == -5 / 6.0
p = Piecewise((0, x < 0), (1, x < 1), (0, x < 2), (1, x < 3), (0, True))
assert integrate(p, (x, -oo, oo)) == 2
p = Piecewise((x, x < -10), (x**2, x <= -1), (x, 1 < x))
assert integrate(p, (x, -2, 2)) == Undefined
# Test commutativity
assert isinstance(p, Piecewise) and p.is_commutative is True
def test_is_zero():
from sympy.abc import x, m, n
assert Integral(0, (x, 1, x)).is_zero
assert Integral(1, (x, 1, 1)).is_zero
assert Integral(1, (x, 1, 2)).is_zero is False
assert Integral(sin(m*x)*cos(n*x), (x, 0, 2*pi)).is_zero is None
def test_issue_2802():
f, g, h = map(Function, 'fgh')
a = Symbol('a')
D = Derivative(f(x), x)
G = Derivative(g(a), a)
assert solve(f(x) + f(x).diff(x), f(x)) == \
[-D]
assert solve(f(x) - 3, f(x)) == \
[3]
assert solve(f(x) - 3*f(x).diff(x), f(x)) == \
[3*D]
assert solve([f(x) - 3*f(x).diff(x)], f(x)) == \
{f(x): 3*D}
assert solve([f(x) - 3*f(x).diff(x), f(x)**2 - y + 4], f(x), y) == \
[{f(x): 3*D, y: 9*D**2 + 4}]
assert solve(-f(a)**2*g(a)**2 + f(a)**2*h(a)**2 + g(a).diff(a),
h(a), g(a), set=True) == \
([g(a)], set([
(-sqrt(h(a)**2 + G/f(a)**2),),
(sqrt(h(a)**2 + G/f(a)**2),)]))
args = [f(x).diff(x, 2) * (f(x) + g(x)) - g(x)**2 + 2, f(x), g(x)]
assert set(solve(*args)) == \
set([(-sqrt(2), sqrt(2)), (sqrt(2), -sqrt(2))])
eqs = [f(x)**2 + g(x) - 2 * f(x).diff(x), g(x)**2 - 4]
assert solve(eqs, f(x), g(x), set=True) == \
([f(x), g(x)], set([
(-sqrt(2*D - 2), S(2)),
(sqrt(2*D - 2), S(2)),
(-sqrt(2*D + 2), -S(2)),
(sqrt(2*D + 2), -S(2))]))
# the underlying problem was in solve_linear that was not masking off
# anything but a Mul or Add; it now raises an error if it gets anything
# but a symbol and solve handles the substitutions necessary so solve_linear
# won't make this error
raises(ValueError,
lambda: solve_linear(f(x) + f(x).diff(x), symbols=[f(x)]))
assert solve_linear(f(x) + f(x).diff(x), symbols=[x]) == \
(f(x) + Derivative(f(x), x), 1)
assert solve_linear(f(x) + Integral(x, (x, y)), symbols=[x]) == \
(f(x) + Integral(x, (x, y)), 1)
assert solve_linear(f(x) + Integral(x, (x, y)) + x, symbols=[x]) == \
(x + f(x) + Integral(x, (x, y)), 1)
assert solve_linear(f(y) + Integral(x, (x, y)) + x, symbols=[x]) == \
(x, -f(y) - Integral(x, (x, y)))
assert solve_linear(x - f(x)/a + (f(x) - 1)/a, symbols=[x]) == \
(x, 1/a)
assert solve_linear(x + Derivative(2*x, x)) == \
(x, -2)
assert solve_linear(x + Integral(x, y), symbols=[x]) == \
(x, 0)
assert solve_linear(x + Integral(x, y) - 2, symbols=[x]) == \
(x, 2/(y + 1))
assert set(solve(x + exp(x)**2, exp(x))) == \
set([-sqrt(-x), sqrt(-x)])
assert solve(x + exp(x), x, implicit=True) == \
[-exp(x)]
assert solve(cos(x) - sin(x), x, implicit=True) == []
assert solve(x - sin(x), x, implicit=True) == \
[sin(x)]
assert solve(x**2 + x - 3, x, implicit=True) == \
[-x**2 + 3]
assert solve(x**2 + x - 3, x**2, implicit=True) == \
[-x + 3]
def test_is_number():
from sympy.abc import x, y, z
from sympy import cos, sin
assert Integral(x).is_number is False
assert Integral(1, x).is_number is False
assert Integral(1, (x, 1)).is_number is True
assert Integral(1, (x, 1, 2)).is_number is True
assert Integral(1, (x, 1, y)).is_number is False
assert Integral(x, y).is_number is False
assert Integral(x, (y, 1, x)).is_number is False
assert Integral(x, (y, 1, 2)).is_number is False
assert Integral(x, (x, 1, 2)).is_number is True
assert Integral(x, (y, 1, 1)).is_number is True
assert Integral(x*y, (x, 1, 2), (y, 1, 3)).is_number is True
assert Integral(x*y, (x, 1, 2), (y, 1, z)).is_number is False
assert Integral(x, (x, 1)).is_number is True
assert Integral(x, (x, 1, Integral(y, (y, 1, 2)))).is_number is True
# it is possible to get a false negative if the integrand is
# actually an unsimplified zero, but this is true of is_number in general.
assert Integral(sin(x)**2 + cos(x)**2 - 1, x).is_number is False
def test_meijerint():
from sympy import symbols, expand, arg
s, t, mu = symbols('s t mu', real=True)
assert integrate(
meijerg([], [], [0], [], s * t) *
meijerg([], [], [mu / 2], [-mu / 2], t**2 / 4),
(t, 0, oo)).is_Piecewise
s = symbols('s', positive=True)
assert integrate(x**s*meijerg([[], []], [[0], []], x), (x, 0, oo)) == \
gamma(s + 1)
assert integrate(x**s * meijerg([[], []], [[0], []], x), (x, 0, oo),
meijerg=True) == gamma(s + 1)
assert isinstance(
integrate(x**s * meijerg([[], []], [[0], []], x), (x, 0, oo),
meijerg=False), Integral)
assert meijerint_indefinite(exp(x), x) == exp(x)
# TODO what simplifications should be done automatically?
# This tests "extra case" for antecedents_1.
a, b = symbols('a b', positive=True)
assert simplify(meijerint_definite(x**a, x, 0, b)[0]) == \
b**(a + 1)/(a + 1)
# This tests various conditions and expansions:
meijerint_definite((x + 1)**3 * exp(-x), x, 0, oo) == (16, True)
# Again, how about simplifications?
sigma, mu = symbols('sigma mu', positive=True)
i, c = meijerint_definite(exp(-((x - mu) / (2 * sigma))**2), x, 0, oo)
assert simplify(i) == sqrt(pi) * sigma * (erf(mu / (2 * sigma)) + 1)
assert c == True
i, _ = meijerint_definite(exp(-mu * x) * exp(sigma * x), x, 0, oo)
# TODO it would be nice to test the condition
assert simplify(i) == 1 / (mu - sigma)
# Test substitutions to change limits
assert meijerint_definite(exp(x), x, -oo, 2) == (exp(2), True)
assert expand(meijerint_definite(exp(x), x, 0, I)[0]) == exp(I) - 1
assert expand(meijerint_definite(exp(-x), x, 0, x)[0]) == \
1 - exp(-exp(I*arg(x))*abs(x))
# Test -oo to oo
assert meijerint_definite(exp(-x**2), x, -oo, oo) == (sqrt(pi), True)
assert meijerint_definite(exp(-abs(x)), x, -oo, oo) == (2, True)
assert meijerint_definite(exp(-(2*x - 3)**2), x, -oo, oo) == \
(sqrt(pi)/2, True)
assert meijerint_definite(exp(-abs(2 * x - 3)), x, -oo, oo) == (1, True)
assert meijerint_definite(
exp(-((x - mu) / sigma)**2 / 2) / sqrt(2 * pi * sigma**2), x, -oo,
oo) == (1, True)
# Test one of the extra conditions for 2 g-functinos
assert meijerint_definite(exp(-x) * sin(x), x, 0, oo) == (S(1) / 2, True)
# Test a bug
def res(n):
return (1 / (1 + x**2)).diff(x, n).subs(x, 1) * (-1)**n
for n in range(6):
assert integrate(exp(-x)*sin(x)*x**n, (x, 0, oo), meijerg=True) == \
res(n)
# This used to test trigexpand... now it is done by linear substitution
assert simplify(integrate(exp(-x) * sin(x + a), (x, 0, oo),
meijerg=True)) == sqrt(2) * sin(a + pi / 4) / 2
# Test the condition 14 from prudnikov.
# (This is besselj*besselj in disguise, to stop the product from being
# recognised in the tables.)
a, b, s = symbols('a b s')
from sympy import And, re
assert meijerint_definite(meijerg([], [], [a/2], [-a/2], x/4)
*meijerg([], [], [b/2], [-b/2], x/4)*x**(s - 1), x, 0, oo) == \
(4*2**(2*s - 2)*gamma(-2*s + 1)*gamma(a/2 + b/2 + s)
/(gamma(-a/2 + b/2 - s + 1)*gamma(a/2 - b/2 - s + 1)
*gamma(a/2 + b/2 - s + 1)),
And(0 < -2*re(4*s) + 8, 0 < re(a/2 + b/2 + s), re(2*s) < 1))
# test a bug
assert integrate(sin(x**a)*sin(x**b), (x, 0, oo), meijerg=True) == \
Integral(sin(x**a)*sin(x**b), (x, 0, oo))
# test better hyperexpand
assert integrate(exp(-x**2)*log(x), (x, 0, oo), meijerg=True) == \
(sqrt(pi)*polygamma(0, S(1)/2)/4).expand()
# Test hyperexpand bug.
from sympy import lowergamma
n = symbols('n', integer=True)
assert simplify(integrate(exp(-x)*x**n, x, meijerg=True)) == \
lowergamma(n + 1, x)
# Test a bug with argument 1/x
alpha = symbols('alpha', positive=True)
assert meijerint_definite((2 - x)**alpha*sin(alpha/x), x, 0, 2) == \
(sqrt(pi)*alpha*gamma(alpha + 1)*meijerg(((), (alpha/2 + S(1)/2,
alpha/2 + 1)), ((0, 0, S(1)/2), (-S(1)/2,)), alpha**S(2)/16)/4, True)
# test a bug related to 3016
a, s = symbols('a s', positive=True)
assert simplify(integrate(x**s*exp(-a*x**2), (x, -oo, oo))) == \
a**(-s/2 - S(1)/2)*((-1)**s + 1)*gamma(s/2 + S(1)/2)/2
def test_nested_doit():
e = Integral(Integral(x, x), x)
f = Integral(x, x, x)
assert e.doit() == f.doit()
def test_risch_option():
# risch=True only allowed on indefinite integrals
raises(ValueError, lambda: integrate(1/log(x), (x, 0, oo), risch=True))
assert integrate(exp(-x**2), x, risch=True) == NonElementaryIntegral(exp(-x**2), x)
assert integrate(log(1/x)*y, x, y, risch=True) == y**2*(x*log(1/x)/2 + x/2)
assert integrate(erf(x), x, risch=True) == Integral(erf(x), x)
def test_as_sum_left():
e = Integral((x + y)**2, (x, 0, 1))
assert e.as_sum(1, method="left").expand() == y**2
assert e.as_sum(2, method="left").expand() == S(1)/8 + y/2 + y**2
assert e.as_sum(3, method="left").expand() == S(5)/27 + 2*y/3 + y**2
assert e.as_sum(4, method="left").expand() == S(7)/32 + 3*y/4 + y**2
def test_issue_3154():
# Note: this used to raise NotImplementedError
assert integrate((sqrt(1 - x) + sqrt(1 + x))**2/x, x, meijerg=True) == \
Integral((sqrt(-x + 1) + sqrt(x + 1))**2/x, x)
def test_integration_variable():
raises(ValueError, lambda: Integral(exp(-x**2), 3))
raises(ValueError, lambda: Integral(exp(-x**2), (3, -oo, oo)))
def test_issue_2079():
assert integrate(sin(x)*f(y, z), (x, 0, pi), (y, 0, pi), (z, 0, pi)) == \
Integral(2*f(y, z), (y, 0, pi), (z, 0, pi))
def test_transform():
a = Integral(x**2 + 1, (x, -1, 2))
fx = x
fy = 3 * y + 1
assert a.doit() == a.transform(fx, fy).doit()
assert a.transform(fx, fy).transform(fy, fx) == a
fx = 3 * x + 1
fy = y
assert a.transform(fx, fy).transform(fy, fx) == a
a = Integral(sin(1 / x), (x, 0, 1))
assert a.transform(x, 1 / y) == Integral(sin(y) / y**2, (y, 1, oo))
assert a.transform(x, 1 / y).transform(y, 1 / x) == a
a = Integral(exp(-x**2), (x, -oo, oo))
assert a.transform(x, 2 * y) == Integral(2 * exp(-4 * y**2), (y, -oo, oo))
# < 3 arg limit handled properly
assert Integral(x, x).transform(x, a*y).doit() == \
Integral(y*a**2, y).doit()
_3 = S(3)
assert Integral(x, (x, 0, -_3)).transform(x, 1/y).doit() == \
Integral(-1/x**3, (x, -oo, -1/_3)).doit()
assert Integral(x, (x, 0, _3)).transform(x, 1/y) == \
Integral(y**(-3), (y, 1/_3, oo))
def test_integrate_functions():
# issue 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(f(x) * diff(f(x), x), x) == f(x)**2 / 2
assert integrate(diff(f(x), x) / f(x), x) == log(f(x))
def euler_maclaurin(self, m=0, n=0, eps=0, eval_integral=True):
"""
Return an Euler-Maclaurin approximation of self, where m is the
number of leading terms to sum directly and n is the number of
terms in the tail.
With m = n = 0, this is simply the corresponding integral
plus a first-order endpoint correction.
Returns (s, e) where s is the Euler-Maclaurin approximation
and e is the estimated error (taken to be the magnitude of
the first omitted term in the tail):
>>> from sympy.abc import k, a, b
>>> from sympy import Sum
>>> Sum(1/k, (k, 2, 5)).doit().evalf()
1.28333333333333
>>> s, e = Sum(1/k, (k, 2, 5)).euler_maclaurin()
>>> s
-log(2) + 7/20 + log(5)
>>> from sympy import sstr
>>> print(sstr((s.evalf(), e.evalf()), full_prec=True))
(1.26629073187415, 0.0175000000000000)
The endpoints may be symbolic:
>>> s, e = Sum(1/k, (k, a, b)).euler_maclaurin()
>>> s
-log(a) + log(b) + 1/(2*b) + 1/(2*a)
>>> e
Abs(1/(12*b**2) - 1/(12*a**2))
If the function is a polynomial of degree at most 2n+1, the
Euler-Maclaurin formula becomes exact (and e = 0 is returned):
>>> Sum(k, (k, 2, b)).euler_maclaurin()
(b**2/2 + b/2 - 1, 0)
>>> Sum(k, (k, 2, b)).doit()
b**2/2 + b/2 - 1
With a nonzero eps specified, the summation is ended
as soon as the remainder term is less than the epsilon.
"""
from sympy.functions import bernoulli, factorial
from sympy.integrals import Integral
m = int(m)
n = int(n)
f = self.function
if len(self.limits) != 1:
raise ValueError("More than 1 limit")
i, a, b = self.limits[0]
if (a > b) == True:
if a - b == 1:
return S.Zero, S.Zero
a, b = b + 1, a - 1
f = -f
s = S.Zero
if m:
if b.is_Integer and a.is_Integer:
m = min(m, b - a + 1)
if not eps or f.is_polynomial(i):
for k in range(m):
s += f.subs(i, a + k)
else:
term = f.subs(i, a)
if term:
test = abs(term.evalf(3)) < eps
if test == True:
return s, abs(term)
elif not (test == False):
# a symbolic Relational class, can't go further
return term, S.Zero
s += term
for k in range(1, m):
term = f.subs(i, a + k)
if abs(term.evalf(3)) < eps and term != 0:
return s, abs(term)
s += term
if b - a + 1 == m:
return s, S.Zero
a += m
x = Dummy('x')
I = Integral(f.subs(i, x), (x, a, b))
if eval_integral:
I = I.doit()
s += I
def fpoint(expr):
if b is S.Infinity:
return expr.subs(i, a), 0
return expr.subs(i, a), expr.subs(i, b)
fa, fb = fpoint(f)
iterm = (fa + fb)/2
g = f.diff(i)
for k in range(1, n + 2):
ga, gb = fpoint(g)
term = bernoulli(2*k)/factorial(2*k)*(gb - ga)
if (eps and term and abs(term.evalf(3)) < eps) or (k > n):
break
s += term
g = g.diff(i, 2, simplify=False)
return s + iterm, abs(term)
def test_evalf_integrals():
assert NS(Integral(x, (x, 2, 5)), 15) == '10.5000000000000'
gauss = Integral(exp(-x**2), (x, -oo, oo))
assert NS(gauss, 15) == '1.77245385090552'
assert NS(gauss**2 - pi + E * Rational(1, 10**20),
15) in ('2.71828182845904e-20', '2.71828182845905e-20')
# A monster of an integral from http://mathworld.wolfram.com/DefiniteIntegral.html
t = Symbol('t')
a = 8 * sqrt(3) / (1 + 3 * t**2)
b = 16 * sqrt(2) * (3 * t + 1) * sqrt(4 * t**2 + t + 1)**3
c = (3 * t**2 + 1) * (11 * t**2 + 2 * t + 3)**2
d = sqrt(2) * (249 * t**2 + 54 * t + 65) / (11 * t**2 + 2 * t + 3)**2
f = a - b / c - d
assert NS(Integral(f, (t, 0, 1)), 50) == \
NS((3*sqrt(2) - 49*pi + 162*atan(sqrt(2)))/12, 50)
# http://mathworld.wolfram.com/VardisIntegral.html
assert NS(Integral(log(log(1/x))/(1 + x + x**2), (x, 0, 1)), 15) == \
NS('pi/sqrt(3) * log(2*pi**(5/6) / gamma(1/6))', 15)
# http://mathworld.wolfram.com/AhmedsIntegral.html
assert NS(
Integral(
atan(sqrt(x**2 + 2)) / (sqrt(x**2 + 2) * (x**2 + 1)), (x, 0, 1)),
15) == NS(5 * pi**2 / 96, 15)
# http://mathworld.wolfram.com/AbelsIntegral.html
assert NS(
Integral(x / ((exp(pi * x) - exp(-pi * x)) * (x**2 + 1)), (x, 0, oo)),
15) == NS('log(2)/2-1/4', 15)
# Complex part trimming
# http://mathworld.wolfram.com/VardisIntegral.html
assert NS(Integral(log(log(sin(x)/cos(x))), (x, pi/4, pi/2)), 15, chop=True) == \
NS('pi/4*log(4*pi**3/gamma(1/4)**4)', 15)
#
# Endpoints causing trouble (rounding error in integration points -> complex log)
assert NS(2 + Integral(log(2 * cos(x / 2)), (x, -pi, pi)), 17,
chop=True) == NS(2, 17)
assert NS(2 + Integral(log(2 * cos(x / 2)), (x, -pi, pi)), 20,
chop=True) == NS(2, 20)
assert NS(2 + Integral(log(2 * cos(x / 2)), (x, -pi, pi)), 22,
chop=True) == NS(2, 22)
# Needs zero handling
assert NS(pi - 4 * Integral('sqrt(1-x**2)', (x, 0, 1)),
15,
maxn=30,
chop=True) in ('0.0', '0')
# Oscillatory quadrature
a = Integral(sin(x) / x**2, (x, 1, oo)).evalf(maxn=15)
assert 0.49 < a < 0.51
assert NS(Integral(sin(x) / x**2, (x, 1, oo)),
quad='osc') == '0.504067061906928'
assert NS(Integral(cos(pi * x + 1) / x, (x, -oo, -1)),
quad='osc') == '0.276374705640365'
# indefinite integrals aren't evaluated
assert NS(Integral(x, x)) == 'Integral(x, x)'
assert NS(Integral(x, (x, y))) == 'Integral(x, (x, y))'
