def test_si():
assert Si(I*x) == I*Shi(x)
assert Shi(I*x) == I*Si(x)
assert Si(-I*x) == -I*Shi(x)
assert Shi(-I*x) == -I*Si(x)
assert Si(-x) == -Si(x)
assert Shi(-x) == -Shi(x)
assert Si(exp_polar(2*pi*I)*x) == Si(x)
assert Si(exp_polar(-2*pi*I)*x) == Si(x)
assert Shi(exp_polar(2*pi*I)*x) == Shi(x)
assert Shi(exp_polar(-2*pi*I)*x) == Shi(x)
assert Si(oo) == pi/2
assert Si(-oo) == -pi/2
assert Shi(oo) is oo
assert Shi(-oo) is -oo
assert mytd(Si(x), sin(x)/x, x)
assert mytd(Shi(x), sinh(x)/x, x)
assert mytn(Si(x), Si(x).rewrite(Ei),
-I*(-Ei(x*exp_polar(-I*pi/2))/2
+ Ei(x*exp_polar(I*pi/2))/2 - I*pi) + pi/2, x)
assert mytn(Si(x), Si(x).rewrite(expint),
-I*(-expint(1, x*exp_polar(-I*pi/2))/2 +
expint(1, x*exp_polar(I*pi/2))/2) + pi/2, x)
assert mytn(Shi(x), Shi(x).rewrite(Ei),
Ei(x)/2 - Ei(x*exp_polar(I*pi))/2 + I*pi/2, x)
assert mytn(Shi(x), Shi(x).rewrite(expint),
expint(1, x)/2 - expint(1, x*exp_polar(I*pi))/2 - I*pi/2, x)
assert tn_arg(Si)
assert tn_arg(Shi)
assert Si(x).nseries(x, n=8) == \
x - x**3/18 + x**5/600 - x**7/35280 + O(x**9)
assert Shi(x).nseries(x, n=8) == \
x + x**3/18 + x**5/600 + x**7/35280 + O(x**9)
assert Si(sin(x)).nseries(x, n=5) == x - 2*x**3/9 + 17*x**5/450 + O(x**6)
assert Si(x).nseries(x, 1, n=3) == \
Si(1) + (x - 1)*sin(1) + (x - 1)**2*(-sin(1)/2 + cos(1)/2) + O((x - 1)**3, (x, 1))
assert Si(x).series(x, oo) == pi/2 - (- 6/x**3 + 1/x \
+ O(x**(-7), (x, oo)))*sin(x)/x - (24/x**4 - 2/x**2 + 1 \
+ O(x**(-7), (x, oo)))*cos(x)/x
t = Symbol('t', Dummy=True)
assert Si(x).rewrite(sinc) == Integral(sinc(t), (t, 0, x))
assert limit(Shi(x), x, S.NegativeInfinity) == -I*pi/2
def test_ci():
m1 = exp_polar(I*pi)
m1_ = exp_polar(-I*pi)
pI = exp_polar(I*pi/2)
mI = exp_polar(-I*pi/2)
assert Ci(m1*x) == Ci(x) + I*pi
assert Ci(m1_*x) == Ci(x) - I*pi
assert Ci(pI*x) == Chi(x) + I*pi/2
assert Ci(mI*x) == Chi(x) - I*pi/2
assert Chi(m1*x) == Chi(x) + I*pi
assert Chi(m1_*x) == Chi(x) - I*pi
assert Chi(pI*x) == Ci(x) + I*pi/2
assert Chi(mI*x) == Ci(x) - I*pi/2
assert Ci(exp_polar(2*I*pi)*x) == Ci(x) + 2*I*pi
assert Chi(exp_polar(-2*I*pi)*x) == Chi(x) - 2*I*pi
assert Chi(exp_polar(2*I*pi)*x) == Chi(x) + 2*I*pi
assert Ci(exp_polar(-2*I*pi)*x) == Ci(x) - 2*I*pi
assert Ci(oo) is S.Zero
assert Ci(-oo) == I*pi
assert Chi(oo) is oo
assert Chi(-oo) is oo
assert mytd(Ci(x), cos(x)/x, x)
assert mytd(Chi(x), cosh(x)/x, x)
assert mytn(Ci(x), Ci(x).rewrite(Ei),
Ei(x*exp_polar(-I*pi/2))/2 + Ei(x*exp_polar(I*pi/2))/2, x)
assert mytn(Chi(x), Chi(x).rewrite(Ei),
Ei(x)/2 + Ei(x*exp_polar(I*pi))/2 - I*pi/2, x)
assert tn_arg(Ci)
assert tn_arg(Chi)
assert Ci(x).nseries(x, n=4) == \
EulerGamma + log(x) - x**2/4 + x**4/96 + O(x**5)
assert Chi(x).nseries(x, n=4) == \
EulerGamma + log(x) + x**2/4 + x**4/96 + O(x**5)
assert Ci(x).series(x, oo) == -cos(x)*(-6/x**3 + 1/x \
+ O(x**(-7), (x, oo)))/x + (24/x**4 - 2/x**2 + 1 \
+ O(x**(-7), (x, oo)))*sin(x)/x
assert limit(log(x) - Ci(2*x), x, 0) == -log(2) - EulerGamma
assert Ci(x).rewrite(uppergamma) == -expint(1, x*exp_polar(-I*pi/2))/2 -\
expint(1, x*exp_polar(I*pi/2))/2
assert Ci(x).rewrite(expint) == -expint(1, x*exp_polar(-I*pi/2))/2 -\
expint(1, x*exp_polar(I*pi/2))/2
raises(ArgumentIndexError, lambda: Ci(x).fdiff(2))
def test_ei():
assert Ei(0) is S.NegativeInfinity
assert Ei(oo) is S.Infinity
assert Ei(-oo) is S.Zero
assert tn_branch(Ei)
assert mytd(Ei(x), exp(x)/x, x)
assert mytn(Ei(x), Ei(x).rewrite(uppergamma),
-uppergamma(0, x*polar_lift(-1)) - I*pi, x)
assert mytn(Ei(x), Ei(x).rewrite(expint),
-expint(1, x*polar_lift(-1)) - I*pi, x)
assert Ei(x).rewrite(expint).rewrite(Ei) == Ei(x)
assert Ei(x*exp_polar(2*I*pi)) == Ei(x) + 2*I*pi
assert Ei(x*exp_polar(-2*I*pi)) == Ei(x) - 2*I*pi
assert mytn(Ei(x), Ei(x).rewrite(Shi), Chi(x) + Shi(x), x)
assert mytn(Ei(x*polar_lift(I)), Ei(x*polar_lift(I)).rewrite(Si),
Ci(x) + I*Si(x) + I*pi/2, x)
assert Ei(log(x)).rewrite(li) == li(x)
assert Ei(2*log(x)).rewrite(li) == li(x**2)
assert gruntz(Ei(x+exp(-x))*exp(-x)*x, x, oo) == 1
assert Ei(x).series(x) == EulerGamma + log(x) + x + x**2/4 + \
x**3/18 + x**4/96 + x**5/600 + O(x**6)
assert Ei(x).series(x, 1, 3) == Ei(1) + E*(x - 1) + O((x - 1)**3, (x, 1))
assert Ei(x).series(x, oo) == \
(120/x**5 + 24/x**4 + 6/x**3 + 2/x**2 + 1/x + 1 + O(x**(-6), (x, oo)))*exp(x)/x
assert str(Ei(cos(2)).evalf(n=10)) == '-0.6760647401'
raises(ArgumentIndexError, lambda: Ei(x).fdiff(2))
def test_function__eval_nseries():
n = Symbol('n')
assert sin(x)._eval_nseries(x, 2, None) == x + O(x**2)
assert sin(x + 1)._eval_nseries(x, 2, None) == x*cos(1) + sin(1) + O(x**2)
assert sin(pi*(1 - x))._eval_nseries(x, 2, None) == pi*x + O(x**2)
assert acos(1 - x**2)._eval_nseries(x, 2, None) == sqrt(2)*sqrt(x**2) + O(x**2)
assert polygamma(n, x + 1)._eval_nseries(x, 2, None) == \
polygamma(n, 1) + polygamma(n + 1, 1)*x + O(x**2)
raises(PoleError, lambda: sin(1/x)._eval_nseries(x, 2, None))
assert acos(1 - x)._eval_nseries(x, 2, None) == sqrt(2)*sqrt(x) + sqrt(2)*x**(S(3)/2)/12 + O(x**2)
assert acos(1 + x)._eval_nseries(x, 2, None) == sqrt(2)*sqrt(-x) + sqrt(2)*(-x)**(S(3)/2)/12 + O(x**2)
assert loggamma(1/x)._eval_nseries(x, 0, None) == \
log(x)/2 - log(x)/x - 1/x + O(1, x)
assert loggamma(log(1/x)).nseries(x, n=1, logx=y) == loggamma(-y)
# issue 6725:
assert expint(Rational(3, 2), -x)._eval_nseries(x, 5, None) == \
2 - 2*sqrt(pi)*sqrt(-x) - 2*x + x**2 + x**3/3 + x**4/12 + 4*I*x**(S(3)/2)*sqrt(-x)/3 + \
2*I*x**(S(5)/2)*sqrt(-x)/5 + 2*I*x**(S(7)/2)*sqrt(-x)/21 + O(x**5)
assert sin(sqrt(x))._eval_nseries(x, 3, None) == \
sqrt(x) - x**Rational(3, 2)/6 + x**Rational(5, 2)/120 + O(x**3)
# issue 19065:
s1 = f(x,y).series(y, n=2)
assert {i.name for i in s1.atoms(Symbol)} == {'x', 'xi', 'y'}
xi = Symbol('xi')
s2 = f(xi, y).series(y, n=2)
assert {i.name for i in s2.atoms(Symbol)} == {'xi', 'xi0', 'y'}
def test_uppergamma():
from sympy.functions.special.error_functions import expint
from sympy.functions.special.hyper import meijerg
assert uppergamma(4, 0) == 6
assert uppergamma(x, y).diff(y) == -y**(x - 1)*exp(-y)
assert td(uppergamma(randcplx(), y), y)
assert uppergamma(x, y).diff(x) == \
uppergamma(x, y)*log(y) + meijerg([], [1, 1], [0, 0, x], [], y)
assert td(uppergamma(x, randcplx()), x)
p = Symbol('p', positive=True)
assert uppergamma(0, p) == -Ei(-p)
assert uppergamma(p, 0) == gamma(p)
assert uppergamma(S.Half, x) == sqrt(pi)*erfc(sqrt(x))
assert not uppergamma(S.Half - 3, x).has(uppergamma)
assert not uppergamma(S.Half + 3, x).has(uppergamma)
assert uppergamma(S.Half, x, evaluate=False).has(uppergamma)
assert tn(uppergamma(S.Half + 3, x, evaluate=False),
uppergamma(S.Half + 3, x), x)
assert tn(uppergamma(S.Half - 3, x, evaluate=False),
uppergamma(S.Half - 3, x), x)
assert unchanged(uppergamma, x, -oo)
assert unchanged(uppergamma, x, 0)
assert tn_branch(-3, uppergamma)
assert tn_branch(-4, uppergamma)
assert tn_branch(Rational(1, 3), uppergamma)
assert tn_branch(pi, uppergamma)
assert uppergamma(3, exp_polar(4*pi*I)*x) == uppergamma(3, x)
assert uppergamma(y, exp_polar(5*pi*I)*x) == \
exp(4*I*pi*y)*uppergamma(y, x*exp_polar(pi*I)) + \
gamma(y)*(1 - exp(4*pi*I*y))
assert uppergamma(-2, exp_polar(5*pi*I)*x) == \
uppergamma(-2, x*exp_polar(I*pi)) - 2*pi*I
assert uppergamma(-2, x) == expint(3, x)/x**2
assert conjugate(uppergamma(x, y)) == uppergamma(conjugate(x), conjugate(y))
assert unchanged(conjugate, uppergamma(x, -oo))
assert uppergamma(x, y).rewrite(expint) == y**x*expint(-x + 1, y)
assert uppergamma(x, y).rewrite(lowergamma) == gamma(x) - lowergamma(x, y)
assert uppergamma(70, 6) == 69035724522603011058660187038367026272747334489677105069435923032634389419656200387949342530805432320*exp(-6)
assert (uppergamma(S(77) / 2, 6) - uppergamma(S(77) / 2, 6, evaluate=False)).evalf() < 1e-16
assert (uppergamma(-S(77) / 2, 6) - uppergamma(-S(77) / 2, 6, evaluate=False)).evalf() < 1e-16
def test_erfi():
assert erfi(nan) is nan
assert erfi(oo) is S.Infinity
assert erfi(-oo) is S.NegativeInfinity
assert erfi(0) is S.Zero
assert erfi(I*oo) == I
assert erfi(-I*oo) == -I
assert erfi(-x) == -erfi(x)
assert erfi(I*erfinv(x)) == I*x
assert erfi(I*erfcinv(x)) == I*(1 - x)
assert erfi(I*erf2inv(0, x)) == I*x
assert erfi(I*erf2inv(0, x, evaluate=False)) == I*x # To cover code in erfi
assert erfi(I).is_real is False
assert erfi(0, evaluate=False).is_real
assert erfi(0, evaluate=False).is_zero
assert conjugate(erfi(z)) == erfi(conjugate(z))
assert erfi(x).as_leading_term(x) == 2*x/sqrt(pi)
assert erfi(x*y).as_leading_term(y) == 2*x*y/sqrt(pi)
assert (erfi(x*y)/erfi(y)).as_leading_term(y) == x
assert erfi(1/x).as_leading_term(x) == erfi(1/x)
assert erfi(z).rewrite('erf') == -I*erf(I*z)
assert erfi(z).rewrite('erfc') == I*erfc(I*z) - I
assert erfi(z).rewrite('fresnels') == (1 - I)*(fresnelc(z*(1 + I)/sqrt(pi)) -
I*fresnels(z*(1 + I)/sqrt(pi)))
assert erfi(z).rewrite('fresnelc') == (1 - I)*(fresnelc(z*(1 + I)/sqrt(pi)) -
I*fresnels(z*(1 + I)/sqrt(pi)))
assert erfi(z).rewrite('hyper') == 2*z*hyper([S.Half], [3*S.Half], z**2)/sqrt(pi)
assert erfi(z).rewrite('meijerg') == z*meijerg([S.Half], [], [0], [Rational(-1, 2)], -z**2)/sqrt(pi)
assert erfi(z).rewrite('uppergamma') == (sqrt(-z**2)/z*(uppergamma(S.Half,
-z**2)/sqrt(S.Pi) - S.One))
assert erfi(z).rewrite('expint') == sqrt(-z**2)/z - z*expint(S.Half, -z**2)/sqrt(S.Pi)
assert erfi(z).rewrite('tractable') == -I*(-_erfs(I*z)*exp(z**2) + 1)
assert expand_func(erfi(I*z)) == I*erf(z)
assert erfi(x).as_real_imag() == \
(erfi(re(x) - I*im(x))/2 + erfi(re(x) + I*im(x))/2,
-I*(-erfi(re(x) - I*im(x)) + erfi(re(x) + I*im(x)))/2)
assert erfi(x).as_real_imag(deep=False) == \
(erfi(re(x) - I*im(x))/2 + erfi(re(x) + I*im(x))/2,
-I*(-erfi(re(x) - I*im(x)) + erfi(re(x) + I*im(x)))/2)
assert erfi(w).as_real_imag() == (erfi(w), 0)
assert erfi(w).as_real_imag(deep=False) == (erfi(w), 0)
raises(ArgumentIndexError, lambda: erfi(x).fdiff(2))
def test_erfc():
assert erfc(nan) is nan
assert erfc(oo) is S.Zero
assert erfc(-oo) == 2
assert erfc(0) == 1
assert erfc(I*oo) == -oo*I
assert erfc(-I*oo) == oo*I
assert erfc(-x) == S(2) - erfc(x)
assert erfc(erfcinv(x)) == x
assert erfc(I).is_real is False
assert erfc(0, evaluate=False).is_real
assert erfc(0, evaluate=False).is_zero is False
assert erfc(erfinv(x)) == 1 - x
assert conjugate(erfc(z)) == erfc(conjugate(z))
assert erfc(x).as_leading_term(x) is S.One
assert erfc(1/x).as_leading_term(x) == S.Zero
assert erfc(z).rewrite('erf') == 1 - erf(z)
assert erfc(z).rewrite('erfi') == 1 + I*erfi(I*z)
assert erfc(z).rewrite('fresnels') == 1 - (1 + I)*(fresnelc(z*(1 - I)/sqrt(pi)) -
I*fresnels(z*(1 - I)/sqrt(pi)))
assert erfc(z).rewrite('fresnelc') == 1 - (1 + I)*(fresnelc(z*(1 - I)/sqrt(pi)) -
I*fresnels(z*(1 - I)/sqrt(pi)))
assert erfc(z).rewrite('hyper') == 1 - 2*z*hyper([S.Half], [3*S.Half], -z**2)/sqrt(pi)
assert erfc(z).rewrite('meijerg') == 1 - z*meijerg([S.Half], [], [0], [Rational(-1, 2)], z**2)/sqrt(pi)
assert erfc(z).rewrite('uppergamma') == 1 - sqrt(z**2)*(1 - erfc(sqrt(z**2)))/z
assert erfc(z).rewrite('expint') == S.One - sqrt(z**2)/z + z*expint(S.Half, z**2)/sqrt(S.Pi)
assert erfc(z).rewrite('tractable') == _erfs(z)*exp(-z**2)
assert expand_func(erf(x) + erfc(x)) is S.One
assert erfc(x).as_real_imag() == \
(erfc(re(x) - I*im(x))/2 + erfc(re(x) + I*im(x))/2,
-I*(-erfc(re(x) - I*im(x)) + erfc(re(x) + I*im(x)))/2)
assert erfc(x).as_real_imag(deep=False) == \
(erfc(re(x) - I*im(x))/2 + erfc(re(x) + I*im(x))/2,
-I*(-erfc(re(x) - I*im(x)) + erfc(re(x) + I*im(x)))/2)
assert erfc(w).as_real_imag() == (erfc(w), 0)
assert erfc(w).as_real_imag(deep=False) == (erfc(w), 0)
raises(ArgumentIndexError, lambda: erfc(x).fdiff(2))
assert erfc(x).inverse() == erfcinv
def test_li():
z = Symbol("z")
zr = Symbol("z", real=True)
zp = Symbol("z", positive=True)
zn = Symbol("z", negative=True)
assert li(0) is S.Zero
assert li(1) is -oo
assert li(oo) is oo
assert isinstance(li(z), li)
assert unchanged(li, -zp)
assert unchanged(li, zn)
assert diff(li(z), z) == 1/log(z)
assert conjugate(li(z)) == li(conjugate(z))
assert conjugate(li(-zr)) == li(-zr)
assert unchanged(conjugate, li(-zp))
assert unchanged(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)))
assert gruntz(1/li(z), z, oo) is S.Zero
assert li(z).series(z) == log(z)**5/600 + log(z)**4/96 + log(z)**3/18 + log(z)**2/4 + \
log(z) + log(log(z)) + EulerGamma
raises(ArgumentIndexError, lambda: li(z).fdiff(2))
def test_expint():
from sympy.functions.elementary.miscellaneous import Max
from sympy.functions.special.error_functions import (Ci, E1, Ei, Si)
from sympy.functions.special.zeta_functions import lerchphi
from sympy.simplify.simplify import simplify
aneg = Symbol('a', negative=True)
u = Symbol('u', polar=True)
assert mellin_transform(E1(x), x, s) == (gamma(s)/s, (0, oo), True)
assert inverse_mellin_transform(gamma(s)/s, s, x,
(0, oo)).rewrite(expint).expand() == E1(x)
assert mellin_transform(expint(a, x), x, s) == \
(gamma(s)/(a + s - 1), (Max(1 - re(a), 0), oo), True)
# XXX IMT has hickups with complicated strips ...
assert simplify(unpolarify(
inverse_mellin_transform(gamma(s)/(aneg + s - 1), s, x,
(1 - aneg, oo)).rewrite(expint).expand(func=True))) == \
expint(aneg, x)
assert mellin_transform(Si(x), x, s) == \
(-2**s*sqrt(pi)*gamma(s/2 + S.Half)/(
2*s*gamma(-s/2 + 1)), (-1, 0), True)
assert inverse_mellin_transform(-2**s*sqrt(pi)*gamma((s + 1)/2)
/(2*s*gamma(-s/2 + 1)), s, x, (-1, 0)) \
== Si(x)
assert mellin_transform(Ci(sqrt(x)), x, s) == \
(-2**(2*s - 1)*sqrt(pi)*gamma(s)/(s*gamma(-s + S.Half)), (0, 1), True)
assert inverse_mellin_transform(
-4**s*sqrt(pi)*gamma(s)/(2*s*gamma(-s + S.Half)),
s, u, (0, 1)).expand() == Ci(sqrt(u))
# TODO LT of Si, Shi, Chi is a mess ...
assert laplace_transform(Ci(x), x, s) == (-log(1 + s**2)/2/s, 0, True)
assert laplace_transform(expint(a, x), x, s) == \
(lerchphi(s*exp_polar(I*pi), 1, a), 0, re(a) > S.Zero)
assert laplace_transform(expint(1, x), x, s) == (log(s + 1)/s, 0, True)
assert laplace_transform(expint(2, x), x, s) == \
((s - log(s + 1))/s**2, 0, True)
assert inverse_laplace_transform(-log(1 + s**2)/2/s, s, u).expand() == \
Heaviside(u)*Ci(u)
assert inverse_laplace_transform(log(s + 1)/s, s, x).rewrite(expint) == \
Heaviside(x)*E1(x)
assert inverse_laplace_transform((s - log(s + 1))/s**2, s,
x).rewrite(expint).expand() == \
(expint(2, x)*Heaviside(x)).rewrite(Ei).rewrite(expint).expand()
def test_expint():
assert mytn(expint(x, y), expint(x, y).rewrite(uppergamma),
y**(x - 1)*uppergamma(1 - x, y), x)
assert mytd(
expint(x, y), -y**(x - 1)*meijerg([], [1, 1], [0, 0, 1 - x], [], y), x)
assert mytd(expint(x, y), -expint(x - 1, y), y)
assert mytn(expint(1, x), expint(1, x).rewrite(Ei),
-Ei(x*polar_lift(-1)) + I*pi, x)
assert expint(-4, x) == exp(-x)/x + 4*exp(-x)/x**2 + 12*exp(-x)/x**3 \
+ 24*exp(-x)/x**4 + 24*exp(-x)/x**5
assert expint(Rational(-3, 2), x) == \
exp(-x)/x + 3*exp(-x)/(2*x**2) + 3*sqrt(pi)*erfc(sqrt(x))/(4*x**S('5/2'))
assert tn_branch(expint, 1)
assert tn_branch(expint, 2)
assert tn_branch(expint, 3)
assert tn_branch(expint, 1.7)
assert tn_branch(expint, pi)
assert expint(y, x*exp_polar(2*I*pi)) == \
x**(y - 1)*(exp(2*I*pi*y) - 1)*gamma(-y + 1) + expint(y, x)
assert expint(y, x*exp_polar(-2*I*pi)) == \
x**(y - 1)*(exp(-2*I*pi*y) - 1)*gamma(-y + 1) + expint(y, x)
assert expint(2, x*exp_polar(2*I*pi)) == 2*I*pi*x + expint(2, x)
assert expint(2, x*exp_polar(-2*I*pi)) == -2*I*pi*x + expint(2, x)
assert expint(1, x).rewrite(Ei).rewrite(expint) == expint(1, x)
assert expint(x, y).rewrite(Ei) == expint(x, y)
assert expint(x, y).rewrite(Ci) == expint(x, y)
assert mytn(E1(x), E1(x).rewrite(Shi), Shi(x) - Chi(x), x)
assert mytn(E1(polar_lift(I)*x), E1(polar_lift(I)*x).rewrite(Si),
-Ci(x) + I*Si(x) - I*pi/2, x)
assert mytn(expint(2, x), expint(2, x).rewrite(Ei).rewrite(expint),
-x*E1(x) + exp(-x), x)
assert mytn(expint(3, x), expint(3, x).rewrite(Ei).rewrite(expint),
x**2*E1(x)/2 + (1 - x)*exp(-x)/2, x)
assert expint(Rational(3, 2), z).nseries(z) == \
2 + 2*z - z**2/3 + z**3/15 - z**4/84 + z**5/540 - \
2*sqrt(pi)*sqrt(z) + O(z**6)
assert E1(z).series(z) == -EulerGamma - log(z) + z - \
z**2/4 + z**3/18 - z**4/96 + z**5/600 + O(z**6)
assert expint(4, z).series(z) == Rational(1, 3) - z/2 + z**2/2 + \
z**3*(log(z)/6 - Rational(11, 36) + EulerGamma/6 - I*pi/6) - z**4/24 + \
z**5/240 + O(z**6)
assert expint(n, x).series(x, oo, n=3) == \
(n*(n + 1)/x**2 - n/x + 1 + O(x**(-3), (x, oo)))*exp(-x)/x
assert expint(z, y).series(z, 0, 2) == exp(-y)/y - z*meijerg(((), (1, 1)),
((0, 0, 1), ()), y)/y + O(z**2)
raises(ArgumentIndexError, lambda: expint(x, y).fdiff(3))
neg = Symbol('neg', negative=True)
assert Ei(neg).rewrite(Si) == Shi(neg) + Chi(neg) - I*pi
def test_erf():
assert erf(nan) is nan
assert erf(oo) == 1
assert erf(-oo) == -1
assert erf(0) is S.Zero
assert erf(I*oo) == oo*I
assert erf(-I*oo) == -oo*I
assert erf(-2) == -erf(2)
assert erf(-x*y) == -erf(x*y)
assert erf(-x - y) == -erf(x + y)
assert erf(erfinv(x)) == x
assert erf(erfcinv(x)) == 1 - x
assert erf(erf2inv(0, x)) == x
assert erf(erf2inv(0, x, evaluate=False)) == x # To cover code in erf
assert erf(erf2inv(0, erf(erfcinv(1 - erf(erfinv(x)))))) == x
assert erf(I).is_real is False
assert erf(0, evaluate=False).is_real
assert erf(0, evaluate=False).is_zero
assert conjugate(erf(z)) == erf(conjugate(z))
assert erf(x).as_leading_term(x) == 2*x/sqrt(pi)
assert erf(x*y).as_leading_term(y) == 2*x*y/sqrt(pi)
assert (erf(x*y)/erf(y)).as_leading_term(y) == x
assert erf(1/x).as_leading_term(x) == S.One
assert erf(z).rewrite('uppergamma') == sqrt(z**2)*(1 - erfc(sqrt(z**2)))/z
assert erf(z).rewrite('erfc') == S.One - erfc(z)
assert erf(z).rewrite('erfi') == -I*erfi(I*z)
assert erf(z).rewrite('fresnels') == (1 + I)*(fresnelc(z*(1 - I)/sqrt(pi)) -
I*fresnels(z*(1 - I)/sqrt(pi)))
assert erf(z).rewrite('fresnelc') == (1 + I)*(fresnelc(z*(1 - I)/sqrt(pi)) -
I*fresnels(z*(1 - I)/sqrt(pi)))
assert erf(z).rewrite('hyper') == 2*z*hyper([S.Half], [3*S.Half], -z**2)/sqrt(pi)
assert erf(z).rewrite('meijerg') == z*meijerg([S.Half], [], [0], [Rational(-1, 2)], z**2)/sqrt(pi)
assert erf(z).rewrite('expint') == sqrt(z**2)/z - z*expint(S.Half, z**2)/sqrt(S.Pi)
assert limit(exp(x)*exp(x**2)*(erf(x + 1/exp(x)) - erf(x)), x, oo) == \
2/sqrt(pi)
assert limit((1 - erf(z))*exp(z**2)*z, z, oo) == 1/sqrt(pi)
assert limit((1 - erf(x))*exp(x**2)*sqrt(pi)*x, x, oo) == 1
assert limit(((1 - erf(x))*exp(x**2)*sqrt(pi)*x - 1)*2*x**2, x, oo) == -1
assert limit(erf(x)/x, x, 0) == 2/sqrt(pi)
assert limit(x**(-4) - sqrt(pi)*erf(x**2) / (2*x**6), x, 0) == S(1)/3
assert erf(x).as_real_imag() == \
(erf(re(x) - I*im(x))/2 + erf(re(x) + I*im(x))/2,
-I*(-erf(re(x) - I*im(x)) + erf(re(x) + I*im(x)))/2)
assert erf(x).as_real_imag(deep=False) == \
(erf(re(x) - I*im(x))/2 + erf(re(x) + I*im(x))/2,
-I*(-erf(re(x) - I*im(x)) + erf(re(x) + I*im(x)))/2)
assert erf(w).as_real_imag() == (erf(w), 0)
assert erf(w).as_real_imag(deep=False) == (erf(w), 0)
# issue 13575
assert erf(I).as_real_imag() == (0, -I*erf(I))
raises(ArgumentIndexError, lambda: erf(x).fdiff(2))
assert erf(x).inverse() == erfinv
def _eval_rewrite_as_expint(self, s, x, **kwargs):
from sympy.functions.special.error_functions import expint
return expint(1 - s, x) * x**s
def eval(cls, a, z):
from sympy.functions.special.error_functions import expint
if z.is_Number:
if z is S.NaN:
return S.NaN
elif z is S.Infinity:
return S.Zero
elif z.is_zero:
if re(a).is_positive:
return gamma(a)
# We extract branching information here. C/f lowergamma.
nx, n = z.extract_branch_factor()
if a.is_integer and a.is_positive:
nx = unpolarify(z)
if z != nx:
return uppergamma(a, nx)
elif a.is_integer and a.is_nonpositive:
if n != 0:
return -2 * pi * I * n * S.NegativeOne**(
-a) / factorial(-a) + uppergamma(a, nx)
elif n != 0:
return gamma(a) * (1 - exp(2 * pi * I * n * a)) + exp(
2 * pi * I * n * a) * uppergamma(a, nx)
# Special values.
if a.is_Number:
if a is S.Zero and z.is_positive:
return -Ei(-z)
elif a is S.One:
return exp(-z)
elif a is S.Half:
return sqrt(pi) * erfc(sqrt(z))
elif a.is_Integer or (2 * a).is_Integer:
b = a - 1
if b.is_positive:
if a.is_integer:
return exp(-z) * factorial(b) * Add(
*[z**k / factorial(k) for k in range(a)])
else:
return (gamma(a) * erfc(sqrt(z)) +
S.NegativeOne**(a - S(3) / 2) * exp(-z) *
sqrt(z) * Add(*[
gamma(-S.Half - k) * (-z)**k / gamma(1 - a)
for k in range(a - S.Half)
]))
elif b.is_Integer:
return expint(-b, z) * unpolarify(z)**(b + 1)
if not a.is_Integer:
return (S.NegativeOne**(S.Half - a) * pi * erfc(sqrt(z)) /
gamma(1 - a) - z**a * exp(-z) * Add(*[
z**k * gamma(a) / gamma(a + k + 1)
for k in range(S.Half - a)
]))
if a.is_zero and z.is_positive:
return -Ei(-z)
if z.is_zero and re(a).is_positive:
return gamma(a)
def test_periodicity():
x = Symbol('x')
y = Symbol('y')
z = Symbol('z', real=True)
assert periodicity(sin(2*x), x) == pi
assert periodicity((-2)*tan(4*x), x) == pi/4
assert periodicity(sin(x)**2, x) == 2*pi
assert periodicity(3**tan(3*x), x) == pi/3
assert periodicity(tan(x)*cos(x), x) == 2*pi
assert periodicity(sin(x)**(tan(x)), x) == 2*pi
assert periodicity(tan(x)*sec(x), x) == 2*pi
assert periodicity(sin(2*x)*cos(2*x) - y, x) == pi/2
assert periodicity(tan(x) + cot(x), x) == pi
assert periodicity(sin(x) - cos(2*x), x) == 2*pi
assert periodicity(sin(x) - 1, x) == 2*pi
assert periodicity(sin(4*x) + sin(x)*cos(x), x) == pi
assert periodicity(exp(sin(x)), x) == 2*pi
assert periodicity(log(cot(2*x)) - sin(cos(2*x)), x) == pi
assert periodicity(sin(2*x)*exp(tan(x) - csc(2*x)), x) == pi
assert periodicity(cos(sec(x) - csc(2*x)), x) == 2*pi
assert periodicity(tan(sin(2*x)), x) == pi
assert periodicity(2*tan(x)**2, x) == pi
assert periodicity(sin(x%4), x) == 4
assert periodicity(sin(x)%4, x) == 2*pi
assert periodicity(tan((3*x-2)%4), x) == Rational(4, 3)
assert periodicity((sqrt(2)*(x+1)+x) % 3, x) == 3 / (sqrt(2)+1)
assert periodicity((x**2+1) % x, x) is None
assert periodicity(sin(re(x)), x) == 2*pi
assert periodicity(sin(x)**2 + cos(x)**2, x) is S.Zero
assert periodicity(tan(x), y) is S.Zero
assert periodicity(sin(x) + I*cos(x), x) == 2*pi
assert periodicity(x - sin(2*y), y) == pi
assert periodicity(exp(x), x) is None
assert periodicity(exp(I*x), x) == 2*pi
assert periodicity(exp(I*z), z) == 2*pi
assert periodicity(exp(z), z) is None
assert periodicity(exp(log(sin(z) + I*cos(2*z)), evaluate=False), z) == 2*pi
assert periodicity(exp(log(sin(2*z) + I*cos(z)), evaluate=False), z) == 2*pi
assert periodicity(exp(sin(z)), z) == 2*pi
assert periodicity(exp(2*I*z), z) == pi
assert periodicity(exp(z + I*sin(z)), z) is None
assert periodicity(exp(cos(z/2) + sin(z)), z) == 4*pi
assert periodicity(log(x), x) is None
assert periodicity(exp(x)**sin(x), x) is None
assert periodicity(sin(x)**y, y) is None
assert periodicity(Abs(sin(Abs(sin(x)))), x) == pi
assert all(periodicity(Abs(f(x)), x) == pi for f in (
cos, sin, sec, csc, tan, cot))
assert periodicity(Abs(sin(tan(x))), x) == pi
assert periodicity(Abs(sin(sin(x) + tan(x))), x) == 2*pi
assert periodicity(sin(x) > S.Half, x) == 2*pi
assert periodicity(x > 2, x) is None
assert periodicity(x**3 - x**2 + 1, x) is None
assert periodicity(Abs(x), x) is None
assert periodicity(Abs(x**2 - 1), x) is None
assert periodicity((x**2 + 4)%2, x) is None
assert periodicity((E**x)%3, x) is None
assert periodicity(sin(expint(1, x))/expint(1, x), x) is None
# returning `None` for any Piecewise
p = Piecewise((0, x < -1), (x**2, x <= 1), (log(x), True))
assert periodicity(p, x) is None
m = MatrixSymbol('m', 3, 3)
raises(NotImplementedError, lambda: periodicity(sin(m), m))
raises(NotImplementedError, lambda: periodicity(sin(m[0, 0]), m))
raises(NotImplementedError, lambda: periodicity(sin(m), m[0, 0]))
raises(NotImplementedError, lambda: periodicity(sin(m[0, 0]), m[0, 0]))
def test_lowergamma():
from sympy.functions.special.error_functions import expint
from sympy.functions.special.hyper import meijerg
assert lowergamma(x, 0) == 0
assert lowergamma(x, y).diff(y) == y**(x - 1)*exp(-y)
assert td(lowergamma(randcplx(), y), y)
assert td(lowergamma(x, randcplx()), x)
assert lowergamma(x, y).diff(x) == \
gamma(x)*digamma(x) - uppergamma(x, y)*log(y) \
- meijerg([], [1, 1], [0, 0, x], [], y)
assert lowergamma(S.Half, x) == sqrt(pi)*erf(sqrt(x))
assert not lowergamma(S.Half - 3, x).has(lowergamma)
assert not lowergamma(S.Half + 3, x).has(lowergamma)
assert lowergamma(S.Half, x, evaluate=False).has(lowergamma)
assert tn(lowergamma(S.Half + 3, x, evaluate=False),
lowergamma(S.Half + 3, x), x)
assert tn(lowergamma(S.Half - 3, x, evaluate=False),
lowergamma(S.Half - 3, x), x)
assert tn_branch(-3, lowergamma)
assert tn_branch(-4, lowergamma)
assert tn_branch(Rational(1, 3), lowergamma)
assert tn_branch(pi, lowergamma)
assert lowergamma(3, exp_polar(4*pi*I)*x) == lowergamma(3, x)
assert lowergamma(y, exp_polar(5*pi*I)*x) == \
exp(4*I*pi*y)*lowergamma(y, x*exp_polar(pi*I))
assert lowergamma(-2, exp_polar(5*pi*I)*x) == \
lowergamma(-2, x*exp_polar(I*pi)) + 2*pi*I
assert conjugate(lowergamma(x, y)) == lowergamma(conjugate(x), conjugate(y))
assert conjugate(lowergamma(x, 0)) == 0
assert unchanged(conjugate, lowergamma(x, -oo))
assert lowergamma(0, x)._eval_is_meromorphic(x, 0) == False
assert lowergamma(S(1)/3, x)._eval_is_meromorphic(x, 0) == False
assert lowergamma(1, x, evaluate=False)._eval_is_meromorphic(x, 0) == True
assert lowergamma(x, x)._eval_is_meromorphic(x, 0) == False
assert lowergamma(x + 1, x)._eval_is_meromorphic(x, 0) == False
assert lowergamma(1/x, x)._eval_is_meromorphic(x, 0) == False
assert lowergamma(0, x + 1)._eval_is_meromorphic(x, 0) == False
assert lowergamma(S(1)/3, x + 1)._eval_is_meromorphic(x, 0) == True
assert lowergamma(1, x + 1, evaluate=False)._eval_is_meromorphic(x, 0) == True
assert lowergamma(x, x + 1)._eval_is_meromorphic(x, 0) == True
assert lowergamma(x + 1, x + 1)._eval_is_meromorphic(x, 0) == True
assert lowergamma(1/x, x + 1)._eval_is_meromorphic(x, 0) == False
assert lowergamma(0, 1/x)._eval_is_meromorphic(x, 0) == False
assert lowergamma(S(1)/3, 1/x)._eval_is_meromorphic(x, 0) == False
assert lowergamma(1, 1/x, evaluate=False)._eval_is_meromorphic(x, 0) == False
assert lowergamma(x, 1/x)._eval_is_meromorphic(x, 0) == False
assert lowergamma(x + 1, 1/x)._eval_is_meromorphic(x, 0) == False
assert lowergamma(1/x, 1/x)._eval_is_meromorphic(x, 0) == False
assert lowergamma(x, 2).series(x, oo, 3) == \
2**x*(1 + 2/(x + 1))*exp(-2)/x + O(exp(x*log(2))/x**3, (x, oo))
assert lowergamma(
x, y).rewrite(expint) == -y**x*expint(-x + 1, y) + gamma(x)
k = Symbol('k', integer=True)
assert lowergamma(
k, y).rewrite(expint) == -y**k*expint(-k + 1, y) + gamma(k)
k = Symbol('k', integer=True, positive=False)
assert lowergamma(k, y).rewrite(expint) == lowergamma(k, y)
assert lowergamma(x, y).rewrite(uppergamma) == gamma(x) - uppergamma(x, y)
assert lowergamma(70, 6) == factorial(69) - 69035724522603011058660187038367026272747334489677105069435923032634389419656200387949342530805432320 * exp(-6)
assert (lowergamma(S(77) / 2, 6) - lowergamma(S(77) / 2, 6, evaluate=False)).evalf() < 1e-16
assert (lowergamma(-S(77) / 2, 6) - lowergamma(-S(77) / 2, 6, evaluate=False)).evalf() < 1e-16
def test_expint():
""" Test various exponential integrals. """
from sympy.core.symbol import Symbol
from sympy.functions.elementary.complexes import unpolarify
from sympy.functions.elementary.hyperbolic import sinh
from sympy.functions.special.error_functions import (Chi, Ci, Ei, Shi, Si,
expint)
assert simplify(
unpolarify(
integrate(exp(-z * x) / x**y, (x, 1, oo),
meijerg=True,
conds='none').rewrite(expint).expand(
func=True))) == expint(y, z)
assert integrate(exp(-z*x)/x, (x, 1, oo), meijerg=True,
conds='none').rewrite(expint).expand() == \
expint(1, z)
assert integrate(exp(-z*x)/x**2, (x, 1, oo), meijerg=True,
conds='none').rewrite(expint).expand() == \
expint(2, z).rewrite(Ei).rewrite(expint)
assert integrate(exp(-z*x)/x**3, (x, 1, oo), meijerg=True,
conds='none').rewrite(expint).expand() == \
expint(3, z).rewrite(Ei).rewrite(expint).expand()
t = Symbol('t', positive=True)
assert integrate(-cos(x) / x, (x, t, oo), meijerg=True).expand() == Ci(t)
assert integrate(-sin(x)/x, (x, t, oo), meijerg=True).expand() == \
Si(t) - pi/2
assert integrate(sin(x) / x, (x, 0, z), meijerg=True) == Si(z)
assert integrate(sinh(x) / x, (x, 0, z), meijerg=True) == Shi(z)
assert integrate(exp(-x)/x, x, meijerg=True).expand().rewrite(expint) == \
I*pi - expint(1, x)
assert integrate(exp(-x)/x**2, x, meijerg=True).rewrite(expint).expand() \
== expint(1, x) - exp(-x)/x - I*pi
u = Symbol('u', polar=True)
assert integrate(cos(u)/u, u, meijerg=True).expand().as_independent(u)[1] \
== Ci(u)
assert integrate(cosh(u)/u, u, meijerg=True).expand().as_independent(u)[1] \
== Chi(u)
assert integrate(
expint(1, x), x,
meijerg=True).rewrite(expint).expand() == x * expint(1, x) - exp(-x)
assert integrate(expint(2, x), x, meijerg=True
).rewrite(expint).expand() == \
-x**2*expint(1, x)/2 + x*exp(-x)/2 - exp(-x)/2
assert simplify(unpolarify(integrate(expint(y, x), x,
meijerg=True).rewrite(expint).expand(func=True))) == \
-expint(y + 1, x)
assert integrate(Si(x), x, meijerg=True) == x * Si(x) + cos(x)
assert integrate(Ci(u), u, meijerg=True).expand() == u * Ci(u) - sin(u)
assert integrate(Shi(x), x, meijerg=True) == x * Shi(x) - cosh(x)
assert integrate(Chi(u), u, meijerg=True).expand() == u * Chi(u) - sinh(u)
assert integrate(Si(x) * exp(-x), (x, 0, oo), meijerg=True) == pi / 4
assert integrate(expint(1, x) * sin(x), (x, 0, oo),
meijerg=True) == log(2) / 2
def test_issue_14692():
b = Symbol('b', negative=True)
assert laplace_transform(1/(I*x - b), x, s) == \
(-I*exp(I*b*s)*expint(1, b*s*exp_polar(I*pi/2)), 0, True)
