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 equivalent 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_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_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_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_nested_doit():
e = Integral(Integral(x, x), x)
f = Integral(x, x, x)
assert e.doit() == f.doit()
def test_is_number():
from sympy.abc import x, y, z
from sympy import cos, sin
assert Integral(x).is_number == False
assert Integral(1, x).is_number == False
assert Integral(1, (x, 1)).is_number == True
assert Integral(1, (x, 1, 2)).is_number == True
assert Integral(1, (x, 1, y)).is_number == False
assert Integral(x, y).is_number == False
assert Integral(x, (y, 1, x)).is_number == False
assert Integral(x, (y, 1, 2)).is_number == False
assert Integral(x, (x, 1, 2)).is_number == True
assert Integral(x, (y, 1, 1)).is_number == True
assert Integral(x*y, (x, 1, 2), (y, 1, 3)).is_number == True
assert Integral(x*y, (x, 1, 2), (y, 1, z)).is_number == False
assert Integral(x, (x, 1)).is_number == True
assert Integral(x, (x, 1, Integral(y, (y, 1, 2)))).is_number == 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 == False
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'
def xtest_failing_integrals():
#---
# Double integrals not implemented
assert NS(Integral(sqrt(x)+x*y, (x, 1, 2), (y, -1, 1)), 15) == '2.43790283299492'
# double integral + zero detection
assert NS(Integral(sin(x+x*y), (x, -1, 1), (y, -1, 1)), 15) == '0.0'
def test_integrate_functions():
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 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_issue580():
# definite integration of rational functions gives wrong answers
assert NS(Integral(1/(x**2-8*x+17), (x, 2, 4))) == '1.10714871779409'
def test_issue_4199():
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_symbols():
from sympy.abc import x, y, z
assert Integral(0, x).free_symbols == {x}
assert Integral(x).free_symbols == {x}
assert Integral(x, (x, None, y)).free_symbols == {y}
assert Integral(x, (x, y, None)).free_symbols == {y}
assert Integral(x, (x, 1, y)).free_symbols == {y}
assert Integral(x, (x, y, 1)).free_symbols == {y}
assert Integral(x, (x, x, y)).free_symbols == {x, y}
assert Integral(x, x, y).free_symbols == {x, y}
assert Integral(x, (x, 1, 2)).free_symbols == set()
assert Integral(x, (y, 1, 2)).free_symbols == {x}
# pseudo-free in this case
assert Integral(x, (y, z, z)).free_symbols == {x, z}
assert Integral(x, (y, 1, 2), (y, None, None)).free_symbols == {x, y}
assert Integral(x, (y, 1, 2), (x, 1, y)).free_symbols == {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 == \
{x}
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_subs4():
e = Integral(exp(x), (x, 0, y), (t, y, 1))
assert e.subs(y, 3) == Integral(exp(x), (x, 0, 3), (t, 3, 1))
f = Lambda(x, exp(-x**2))
conv = Integral(f(y)*f(y), (y, -oo, oo), (t, x, 1))
assert conv.subs({x:0}) == Integral(exp(-2*y**2), (y, -oo, oo), (t, 0, 1))
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(NotImplementedError, lambda: e.as_sum(oo))
raises(NotImplementedError, lambda: e.as_sum(3, method='xxxx2'))
def test_subs5():
e = Integral(exp(-x**2), x)
assert e.subs(x, 5) == Integral(exp(-25), x)
e = Integral(exp(-x**2), (x, x))
assert e.subs(x, 5) == Integral(exp(-x**2), (x, 5))
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) == Integral(exp(y - 25), x)
assert e.subs(y, 5) == Integral(exp(-x**2 + 5), x)
e = Integral(exp(-x**2+y), (x, x))
assert e.subs(x, 5) == Integral(exp(y - x**2), (x, 5))
assert e.subs(y, 5) == Integral(exp(-x**2 + 5), (x, 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 test_integral_reconstruct():
e = Integral(x**2, (x, -1, 1))
assert e == Integral(*e.args)
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_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_integration_variable():
raises(ValueError, lambda: Integral(exp(-x**2), 3))
raises(ValueError, lambda: Integral(exp(-x**2), (3, -oo, oo)))
def test_series():
from sympy.abc import x
i = Integral(cos(x))
e = i.lseries(x)
assert i.nseries(x, n=8).removeO() == Add(*[e.next() for j in range(4)])
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_issue_1100():
ypos = Symbol('y', positive=True)
assert integrate(exp(-I*2*pi*ypos*x)*x, (x, -oo, oo)) == \
Integral(exp(-I*2*pi*ypos*x)*x, (x, -oo, oo))
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_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_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_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_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))
