def test_roots_mixed():
f = -1936 - 5056 * x - 7592 * x**2 + 2704 * x**3 - 49 * x**4
_re, _im = [], []
p = Poly(f)
for r in p.all_roots():
c, (r, ) = r.as_coeff_mul()
if r.is_real:
r = r.interval
_re.append((c * QQ.to_expr(r.a), c * QQ.to_expr(r.b)))
else:
r = r.interval
_im.append((c * QQ.to_expr(r.ax) + c * I * QQ.to_expr(r.ay),
c * QQ.to_expr(r.bx) + c * I * QQ.to_expr(r.by)))
_nroots = nroots(f)
_sroots = roots(f, multiple=True)
_re = [Interval(a, b) for (a, b) in _re]
_im = [Interval(re(a), re(b)) * Interval(im(a), im(b)) for (a, b) in _im]
_intervals = _re + _im
_sroots = [r.evalf() for r in _sroots]
_nroots = sorted(_nroots, key=lambda x: x.sort_key())
_sroots = sorted(_sroots, key=lambda x: x.sort_key())
for _roots in (_nroots, _sroots):
for i, r in zip(_intervals, _roots):
if r.is_extended_real:
assert r in i
else:
assert (re(r), im(r)) in i
def test_f_expand_complex():
x = Symbol('x', extended_real=True)
assert f(x).expand(complex=True) == I * im(f(x)) + re(f(x))
assert exp(x).expand(complex=True) == exp(x)
assert exp(I * x).expand(complex=True) == cos(x) + I * sin(x)
assert exp(z).expand(complex=True) == cos(im(z))*exp(re(z)) + \
I*sin(im(z))*exp(re(z))
def test_f_expand_complex():
x = Symbol('x', extended_real=True)
assert f(x).expand(complex=True) == I*im(f(x)) + re(f(x))
assert exp(x).expand(complex=True) == exp(x)
assert exp(I*x).expand(complex=True) == cos(x) + I*sin(x)
assert exp(z).expand(complex=True) == cos(im(z))*exp(re(z)) + \
I*sin(im(z))*exp(re(z))
def test_derivatives_issue_4757():
x = Symbol('x', extended_real=True)
y = Symbol('y', imaginary=True)
f = Function('f')
assert re(f(x)).diff(x) == re(f(x).diff(x))
assert im(f(x)).diff(x) == im(f(x).diff(x))
assert re(f(y)).diff(y) == -I * im(f(y).diff(y))
assert im(f(y)).diff(y) == -I * re(f(y).diff(y))
assert Abs(f(x)).diff(x).subs(f(x), 1 + I * x).doit() == x / sqrt(1 + x**2)
assert arg(f(x)).diff(x).subs(f(x),
1 + I * x**2).doit() == 2 * x / (1 + x**4)
assert Abs(f(y)).diff(y).subs(f(y), 1 + y).doit() == -y / sqrt(1 - y**2)
assert arg(f(y)).diff(y).subs(f(y), I + y**2).doit() == 2 * y / (1 + y**4)
def _eval_evalf(self, prec):
""" Careful! any evalf of polar numbers is flaky """
from diofant import im, pi, re
i = im(self.exp)
try:
bad = (i <= -pi or i > pi)
except TypeError:
bad = True
if bad:
return self # cannot evalf for this argument
res = exp(self.exp).evalf(prec)
if i > 0 and im(res) < 0:
# i ~ pi, but exp(I*i) evaluated to argument slightly bigger than pi
return re(res)
return res
def test_catalan():
n = Symbol('n', integer=True)
m = Symbol('n', integer=True, positive=True)
catalans = [1, 1, 2, 5, 14, 42, 132, 429, 1430, 4862, 16796, 58786]
for i, c in enumerate(catalans):
assert catalan(i) == c
assert catalan(n).rewrite(factorial).subs({n: i}) == c
assert catalan(n).rewrite(Product).subs({n: i}).doit() == c
assert catalan(x) == catalan(x)
assert catalan(2*x).rewrite(binomial) == binomial(4*x, 2*x)/(2*x + 1)
assert catalan(Rational(1, 2)).rewrite(gamma) == 8/(3*pi)
assert catalan(Rational(1, 2)).rewrite(factorial).rewrite(gamma) ==\
8 / (3 * pi)
assert catalan(3*x).rewrite(gamma) == 4**(
3*x)*gamma(3*x + Rational(1, 2))/(sqrt(pi)*gamma(3*x + 2))
assert catalan(x).rewrite(hyper) == hyper((-x + 1, -x), (2,), 1)
assert catalan(n).rewrite(factorial) == factorial(2*n) / (factorial(n + 1)
* factorial(n))
assert isinstance(catalan(n).rewrite(Product), catalan)
assert isinstance(catalan(m).rewrite(Product), Product)
assert diff(catalan(x), x) == (polygamma(
0, x + Rational(1, 2)) - polygamma(0, x + 2) + log(4))*catalan(x)
assert catalan(x).evalf() == catalan(x)
c = catalan(Rational(1, 2)).evalf()
assert str(c) == '0.848826363156775'
c = catalan(I).evalf(3)
assert sstr((re(c), im(c))) == '(0.398, -0.0209)'
def test_AssocOp_Function():
e = Min(-sqrt(3)*cos(pi/18)/6 +
re(1/((Rational(-1, 2) - sqrt(3)*I/2)*cbrt(Rational(1, 6) +
sqrt(3)*I/18)))/3 + sin(pi/18)/2 + 2 +
I*(-cos(pi/18)/2 - sqrt(3)*sin(pi/18)/6 +
im(1/((Rational(-1, 2) - sqrt(3)*I/2)*cbrt(Rational(1, 6) +
sqrt(3)*I/18)))/3),
re(1/((Rational(-1, 2) + sqrt(3)*I/2)*cbrt(Rational(1, 6) + sqrt(3)*I/18)))/3 -
sqrt(3)*cos(pi/18)/6 - sin(pi/18)/2 + 2 +
I*(im(1/((Rational(-1, 2) + sqrt(3)*I/2)*cbrt(Rational(1, 6) +
sqrt(3)*I/18)))/3 -
sqrt(3)*sin(pi/18)/6 + cos(pi/18)/2))
# the following should not raise a recursion error; it
# should raise a value error because the first arg computes
# a non-comparable (prec=1) imaginary part
pytest.raises(ValueError, lambda: e.evalf(2, strict=False))
def test_catalan():
n = Symbol('n', integer=True)
m = Symbol('n', integer=True, positive=True)
catalans = [1, 1, 2, 5, 14, 42, 132, 429, 1430, 4862, 16796, 58786]
for i, c in enumerate(catalans):
assert catalan(i) == c
assert catalan(n).rewrite(factorial).subs({n: i}) == c
assert catalan(n).rewrite(Product).subs({n: i}).doit() == c
assert catalan(x) == catalan(x)
assert catalan(2 *
x).rewrite(binomial) == binomial(4 * x, 2 * x) / (2 * x + 1)
assert catalan(Rational(1, 2)).rewrite(gamma) == 8 / (3 * pi)
assert catalan(Rational(1, 2)).rewrite(factorial).rewrite(gamma) ==\
8 / (3 * pi)
assert catalan(3 * x).rewrite(gamma) == 4**(
3 * x) * gamma(3 * x + Rational(1, 2)) / (sqrt(pi) * gamma(3 * x + 2))
assert catalan(x).rewrite(hyper) == hyper((-x + 1, -x), (2, ), 1)
assert catalan(n).rewrite(factorial) == factorial(
2 * n) / (factorial(n + 1) * factorial(n))
assert isinstance(catalan(n).rewrite(Product), catalan)
assert isinstance(catalan(m).rewrite(Product), Product)
assert diff(catalan(x), x) == (polygamma(0, x + Rational(1, 2)) -
polygamma(0, x + 2) + log(4)) * catalan(x)
assert catalan(x).evalf() == catalan(x)
c = catalan(Rational(1, 2)).evalf()
assert str(c) == '0.848826363156775'
c = catalan(I).evalf(3)
assert sstr((re(c), im(c))) == '(0.398, -0.0209)'
def test_evalf_default():
assert type(sin(4.0)) == Float
assert type(re(sin(I + 1.0))) == Float
assert type(im(sin(I + 1.0))) == Float
assert type(sin(4)) == sin
assert type(polygamma(2.0, 4.0)) == Float
assert type(sin(Rational(1, 4))) == sin
def test_evalf_default():
assert type(sin(4.0)) == Float
assert type(re(sin(I + 1.0))) == Float
assert type(im(sin(I + 1.0))) == Float
assert type(sin(4)) == sin
assert type(polygamma(2.0, 4.0)) == Float
assert type(sin(Rational(1, 4))) == sin
def test_AssocOp_Function():
e = Min(-sqrt(3)*cos(pi/18)/6 +
re(1/((Rational(-1, 2) - sqrt(3)*I/2)*cbrt(Rational(1, 6) +
sqrt(3)*I/18)))/3 + sin(pi/18)/2 + 2 +
I*(-cos(pi/18)/2 - sqrt(3)*sin(pi/18)/6 +
im(1/((Rational(-1, 2) - sqrt(3)*I/2)*cbrt(Rational(1, 6) +
sqrt(3)*I/18)))/3),
re(1/((Rational(-1, 2) + sqrt(3)*I/2)*cbrt(Rational(1, 6) + sqrt(3)*I/18)))/3 -
sqrt(3)*cos(pi/18)/6 - sin(pi/18)/2 + 2 +
I*(im(1/((Rational(-1, 2) + sqrt(3)*I/2)*cbrt(Rational(1, 6) +
sqrt(3)*I/18)))/3 -
sqrt(3)*sin(pi/18)/6 + cos(pi/18)/2))
# the following should not raise a recursion error; it
# should raise a value error because the first arg computes
# a non-comparable (prec=1) imaginary part
pytest.raises(ValueError, lambda: e.evalf(2, strict=False))
def test_evalf_default():
from diofant.functions.special.gamma_functions import polygamma
assert type(sin(4.0)) == Float
assert type(re(sin(I + 1.0))) == Float
assert type(im(sin(I + 1.0))) == Float
assert type(sin(4)) == sin
assert type(polygamma(2.0, 4.0)) == Float
assert type(sin(Rational(1, 4))) == sin
def test_diofantissue_662():
e1 = abs(sqrt(1 + sqrt(2 + I)))
e2 = re(sqrt(I), evaluate=False)
e3 = im(sqrt(I), evaluate=False)
for meth in ('compose', 'groebner'):
assert (minimal_polynomial(e1, method=meth)(x) == x**16 - 4 * x**12 -
12 * x**8 - 8 * x**4 + 4)
assert minimal_polynomial(e2, method=meth)(x) == 2 * x**2 - 1
assert minimal_polynomial(e3, method=meth)(x) == 2 * x**2 - 1
def test_abs_re_im(method):
# issue diofant/diofant#662
e1 = abs(sqrt(1 + sqrt(2 + I)))
e2 = re(sqrt(I), evaluate=False)
e3 = im(sqrt(I), evaluate=False)
assert (minimal_polynomial(e1, method=method)(x) == x**16 - 4 * x**12 -
12 * x**8 - 8 * x**4 + 4)
assert minimal_polynomial(e2, method=method)(x) == 2 * x**2 - 1
assert minimal_polynomial(e3, method=method)(x) == 2 * x**2 - 1
def test_diofantissue_662():
e1 = abs(sqrt(1 + sqrt(2 + I)))
e2 = re(sqrt(I), evaluate=False)
e3 = im(sqrt(I), evaluate=False)
for meth in ('compose', 'groebner'):
assert (minimal_polynomial(e1, method=meth)(x) ==
x**16 - 4*x**12 - 12*x**8 - 8*x**4 + 4)
assert minimal_polynomial(e2, method=meth)(x) == 2*x**2 - 1
assert minimal_polynomial(e3, method=meth)(x) == 2*x**2 - 1
def test_evalc():
x = Symbol('x', extended_real=True)
y = Symbol('y', extended_real=True)
z = Symbol('z')
assert ((x + I * y)**2).expand(complex=True) == x**2 + 2 * I * x * y - y**2
assert expand_complex(z**(2 * I)) == (re(
(re(z) + I * im(z))**(2 * I)) + I * im((re(z) + I * im(z))**(2 * I)))
assert expand_complex(z**(2 * I),
deep=False) == I * im(z**(2 * I)) + re(z**(2 * I))
assert exp(I * x) != cos(x) + I * sin(x)
assert exp(I * x).expand(complex=True) == cos(x) + I * sin(x)
assert exp(I * x +
y).expand(complex=True) == exp(y) * cos(x) + I * sin(x) * exp(y)
assert sin(I * x).expand(complex=True) == I * sinh(x)
assert sin(x + I*y).expand(complex=True) == sin(x)*cosh(y) + \
I * sinh(y) * cos(x)
assert cos(I * x).expand(complex=True) == cosh(x)
assert cos(x + I*y).expand(complex=True) == cos(x)*cosh(y) - \
I * sinh(y) * sin(x)
assert tan(I * x).expand(complex=True) == tanh(x) * I
assert tan(x + I * y).expand(
complex=True) == (sin(2 * x) / (cos(2 * x) + cosh(2 * y)) +
I * sinh(2 * y) / (cos(2 * x) + cosh(2 * y)))
assert sinh(I * x).expand(complex=True) == I * sin(x)
assert sinh(x + I*y).expand(complex=True) == sinh(x)*cos(y) + \
I * sin(y) * cosh(x)
assert cosh(I * x).expand(complex=True) == cos(x)
assert cosh(x + I*y).expand(complex=True) == cosh(x)*cos(y) + \
I * sin(y) * sinh(x)
assert tanh(I * x).expand(complex=True) == tan(x) * I
assert tanh(x + I * y).expand(
complex=True) == ((sinh(x) * cosh(x) + I * cos(y) * sin(y)) /
(sinh(x)**2 + cos(y)**2)).expand()
def test_erfc():
assert erfc(nan) == nan
assert erfc(oo) == 0
assert erfc(-oo) == 2
assert erfc(0) == 1
assert erfc(I * oo) == -oo * I
assert erfc(-I * oo) == oo * I
assert erfc(-x) == Integer(2) - erfc(x)
assert erfc(erfcinv(x)) == x
assert erfc(erfinv(x)) == 1 - x
assert erfc(I).is_extended_real is False
assert erfc(w).is_extended_real is True
assert erfc(z).is_extended_real is None
assert conjugate(erfc(z)) == erfc(conjugate(z))
assert erfc(x).as_leading_term(x) == 1
assert erfc(1 / x).as_leading_term(x) == erfc(1 / x)
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(
[Rational(1, 2)], [Rational(3, 2)], -z**2) / sqrt(pi)
assert erfc(z).rewrite('meijerg') == 1 - z * meijerg(
[Rational(1, 2)], [], [0], [Rational(-1, 2)], z**2) / sqrt(pi)
assert erfc(z).rewrite(
'uppergamma') == 1 - sqrt(z**2) * erf(sqrt(z**2)) / z
assert erfc(z).rewrite('expint') == 1 - sqrt(z**2) / z + z * expint(
Rational(1, 2), z**2) / sqrt(pi)
assert erfc(x).as_real_imag() == \
((erfc(re(x) - I*re(x)*abs(im(x))/abs(re(x)))/2 +
erfc(re(x) + I*re(x)*abs(im(x))/abs(re(x)))/2,
I*(erfc(re(x) - I*re(x)*abs(im(x))/abs(re(x))) -
erfc(re(x) + I*re(x)*abs(im(x))/abs(re(x)))) *
re(x)*abs(im(x))/(2*im(x)*abs(re(x)))))
assert erfc(x).as_real_imag(deep=False) == erfc(x).as_real_imag()
assert erfc(w).as_real_imag() == (erfc(w), 0)
assert erfc(w).as_real_imag(deep=False) == erfc(w).as_real_imag()
assert erfc(I).as_real_imag() == (1, -erfi(1))
pytest.raises(ArgumentIndexError, lambda: erfc(x).fdiff(2))
assert erfc(x).taylor_term(3, x, *(-2 * x / sqrt(pi),
0)) == 2 * x**3 / 3 / sqrt(pi)
assert erfc(x).limit(x, oo) == 0
assert erfc(x).diff(x) == -2 * exp(-x**2) / sqrt(pi)
def test_erf():
assert erf(nan) == nan
assert erf(oo) == 1
assert erf(-oo) == -1
assert erf(0) == 0
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, erf(erfcinv(1 - erf(erfinv(x)))))) == x
assert erf(I).is_extended_real is False
assert erf(w).is_extended_real is True
assert erf(z).is_extended_real is None
assert conjugate(erf(z)) == erf(conjugate(z))
assert erf(x).as_leading_term(x) == 2 * x / sqrt(pi)
assert erf(1 / x).as_leading_term(x) == erf(1 / x)
assert erf(z).rewrite('uppergamma') == sqrt(z**2) * erf(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],
[-S.Half], 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 erf(x).as_real_imag() == \
((erf(re(x) - I*re(x)*Abs(im(x))/Abs(re(x)))/2 +
erf(re(x) + I*re(x)*Abs(im(x))/Abs(re(x)))/2,
I*(erf(re(x) - I*re(x)*Abs(im(x))/Abs(re(x))) -
erf(re(x) + I*re(x)*Abs(im(x))/Abs(re(x)))) *
re(x)*Abs(im(x))/(2*im(x)*Abs(re(x)))))
pytest.raises(ArgumentIndexError, lambda: erf(x).fdiff(2))
def test_evalc():
x = Symbol("x", extended_real=True)
y = Symbol("y", extended_real=True)
z = Symbol("z")
assert ((x + I*y)**2).expand(complex=True) == x**2 + 2*I*x*y - y**2
assert expand_complex(z**(2*I)) == (re((re(z) + I*im(z))**(2*I)) +
I*im((re(z) + I*im(z))**(2*I)))
assert expand_complex(
z**(2*I), deep=False) == I*im(z**(2*I)) + re(z**(2*I))
assert exp(I*x) != cos(x) + I*sin(x)
assert exp(I*x).expand(complex=True) == cos(x) + I*sin(x)
assert exp(I*x + y).expand(complex=True) == exp(y)*cos(x) + I*sin(x)*exp(y)
assert sin(I*x).expand(complex=True) == I * sinh(x)
assert sin(x + I*y).expand(complex=True) == sin(x)*cosh(y) + \
I * sinh(y) * cos(x)
assert cos(I*x).expand(complex=True) == cosh(x)
assert cos(x + I*y).expand(complex=True) == cos(x)*cosh(y) - \
I * sinh(y) * sin(x)
assert tan(I*x).expand(complex=True) == tanh(x) * I
assert tan(x + I*y).expand(complex=True) == (
sin(2*x)/(cos(2*x) + cosh(2*y)) +
I*sinh(2*y)/(cos(2*x) + cosh(2*y)))
assert sinh(I*x).expand(complex=True) == I * sin(x)
assert sinh(x + I*y).expand(complex=True) == sinh(x)*cos(y) + \
I * sin(y) * cosh(x)
assert cosh(I*x).expand(complex=True) == cos(x)
assert cosh(x + I*y).expand(complex=True) == cosh(x)*cos(y) + \
I * sin(y) * sinh(x)
assert tanh(I*x).expand(complex=True) == tan(x) * I
assert tanh(x + I*y).expand(complex=True) == (
(sinh(x)*cosh(x) + I*cos(y)*sin(y)) /
(sinh(x)**2 + cos(y)**2)).expand()
def test_as_real_imag():
n = pi**1000
# the special code for working out the real
# and complex parts of a power with Integer exponent
# should not run if there is no imaginary part, hence
# this should not hang
assert n.as_real_imag() == (n, 0)
# issue sympy/sympy#6261
assert sqrt(x).as_real_imag() == \
(root(re(x)**2 + im(x)**2, 4)*cos(arg(re(x) + I*im(x))/2),
root(re(x)**2 + im(x)**2, 4)*sin(arg(re(x) + I*im(x))/2))
# issue sympy/sympy#3853
a, b = symbols('a,b', extended_real=True)
assert (((1 + sqrt(a + b*I))/2).as_real_imag() ==
(root(a**2 + b**2, 4)*cos(arg(a + I*b)/2)/2 + Rational(1, 2),
root(a**2 + b**2, 4)*sin(arg(a + I*b)/2)/2))
assert sqrt(a**2).as_real_imag() == (sqrt(a**2), 0)
i = symbols('i', imaginary=True)
assert sqrt(i**2).as_real_imag() == (0, abs(i))
def test_as_real_imag():
n = pi**1000
# the special code for working out the real
# and complex parts of a power with Integer exponent
# should not run if there is no imaginary part, hence
# this should not hang
assert n.as_real_imag() == (n, 0)
# issue sympy/sympy#6261
assert sqrt(x).as_real_imag() == \
(root(re(x)**2 + im(x)**2, 4)*cos(arg(re(x) + I*im(x))/2),
root(re(x)**2 + im(x)**2, 4)*sin(arg(re(x) + I*im(x))/2))
# issue sympy/sympy#3853
a, b = symbols('a,b', extended_real=True)
assert (((1 + sqrt(a + b*I))/2).as_real_imag() ==
(root(a**2 + b**2, 4)*cos(arg(a + I*b)/2)/2 + Rational(1, 2),
root(a**2 + b**2, 4)*sin(arg(a + I*b)/2)/2))
assert sqrt(a**2).as_real_imag() == (sqrt(a**2), 0)
i = symbols('i', imaginary=True)
assert sqrt(i**2).as_real_imag() == (0, abs(i))
def test_roots_mixed():
f = -1936 - 5056*x - 7592*x**2 + 2704*x**3 - 49*x**4
_re, _im = intervals(f, all=True)
_nroots = nroots(f)
_sroots = roots(f, multiple=True)
_re = [ Interval(a, b) for (a, b), _ in _re ]
_im = [ Interval(re(a), re(b))*Interval(im(a), im(b)) for (a, b),
_ in _im ]
_intervals = _re + _im
_sroots = [ r.evalf() for r in _sroots ]
_nroots = sorted(_nroots, key=lambda x: x.sort_key())
_sroots = sorted(_sroots, key=lambda x: x.sort_key())
for _roots in (_nroots, _sroots):
for i, r in zip(_intervals, _roots):
if r.is_extended_real:
assert r in i
else:
assert (re(r), im(r)) in i
def test_erfi():
assert erfi(nan) == nan
assert erfi(+oo) == +oo
assert erfi(-oo) == -oo
assert erfi(0) == 0
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).is_extended_real is False
assert erfi(w).is_extended_real is True
assert erfi(z).is_extended_real is None
assert conjugate(erfi(z)) == erfi(conjugate(z))
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(
[Rational(1, 2)], [Rational(3, 2)], z**2) / sqrt(pi)
assert erfi(z).rewrite('meijerg') == z * meijerg(
[Rational(1, 2)], [], [0], [Rational(-1, 2)], -z**2) / sqrt(pi)
assert erfi(z).rewrite('uppergamma') == (
sqrt(-z**2) / z * (uppergamma(Rational(1, 2), -z**2) / sqrt(pi) - 1))
assert erfi(z).rewrite('expint') == sqrt(-z**2) / z - z * expint(
Rational(1, 2), -z**2) / sqrt(pi)
assert erfi(x).as_real_imag() == \
((erfi(re(x) - I*re(x)*abs(im(x))/abs(re(x)))/2 +
erfi(re(x) + I*re(x)*abs(im(x))/abs(re(x)))/2,
I*(erfi(re(x) - I*re(x)*abs(im(x))/abs(re(x))) -
erfi(re(x) + I*re(x)*abs(im(x))/abs(re(x)))) *
re(x)*abs(im(x))/(2*im(x)*abs(re(x)))))
assert erfi(x).as_real_imag(deep=False) == erfi(x).as_real_imag()
assert erfi(w).as_real_imag() == (erfi(w), 0)
assert erfi(w).as_real_imag(deep=False) == erfi(w).as_real_imag()
assert erfi(I).as_real_imag() == (0, erf(1))
pytest.raises(ArgumentIndexError, lambda: erfi(x).fdiff(2))
assert erfi(x).taylor_term(3, x, *(2 * x / sqrt(pi),
0)) == 2 * x**3 / 3 / sqrt(pi)
assert erfi(x).limit(x, oo) == oo
def test_roots_mixed():
f = -1936 - 5056 * x - 7592 * x**2 + 2704 * x**3 - 49 * x**4
_re, _im = intervals(f, all=True)
_nroots = nroots(f)
_sroots = roots(f, multiple=True)
_re = [Interval(a, b) for (a, b), _ in _re]
_im = [
Interval(re(a), re(b)) * Interval(im(a), im(b)) for (a, b), _ in _im
]
_intervals = _re + _im
_sroots = [r.evalf() for r in _sroots]
_nroots = sorted(_nroots, key=lambda x: x.sort_key())
_sroots = sorted(_sroots, key=lambda x: x.sort_key())
for _roots in (_nroots, _sroots):
for i, r in zip(_intervals, _roots):
if r.is_extended_real:
assert r in i
else:
assert (re(r), im(r)) in i
def test_erfc():
assert erfc(nan) == nan
assert erfc(oo) == 0
assert erfc(-oo) == 2
assert erfc(0) == 1
assert erfc(I*oo) == -oo*I
assert erfc(-I*oo) == oo*I
assert erfc(-x) == Integer(2) - erfc(x)
assert erfc(erfcinv(x)) == x
assert erfc(erfinv(x)) == 1 - x
assert erfc(I).is_extended_real is False
assert erfc(w).is_extended_real is True
assert erfc(z).is_extended_real is None
assert conjugate(erfc(z)) == erfc(conjugate(z))
assert erfc(x).as_leading_term(x) == 1
assert erfc(1/x).as_leading_term(x) == erfc(1/x)
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([Rational(1, 2)], [Rational(3, 2)], -z**2)/sqrt(pi)
assert erfc(z).rewrite('meijerg') == 1 - z*meijerg([Rational(1, 2)], [], [0], [Rational(-1, 2)], z**2)/sqrt(pi)
assert erfc(z).rewrite('uppergamma') == 1 - sqrt(z**2)*erf(sqrt(z**2))/z
assert erfc(z).rewrite('expint') == 1 - sqrt(z**2)/z + z*expint(Rational(1, 2), z**2)/sqrt(pi)
assert erfc(x).as_real_imag() == \
((erfc(re(x) - I*re(x)*Abs(im(x))/Abs(re(x)))/2 +
erfc(re(x) + I*re(x)*Abs(im(x))/Abs(re(x)))/2,
I*(erfc(re(x) - I*re(x)*Abs(im(x))/Abs(re(x))) -
erfc(re(x) + I*re(x)*Abs(im(x))/Abs(re(x)))) *
re(x)*Abs(im(x))/(2*im(x)*Abs(re(x)))))
assert erfc(x).as_real_imag(deep=False) == erfc(x).as_real_imag()
assert erfc(w).as_real_imag() == (erfc(w), 0)
assert erfc(w).as_real_imag(deep=False) == erfc(w).as_real_imag()
assert erfc(I).as_real_imag() == (1, -erfi(1))
pytest.raises(ArgumentIndexError, lambda: erfc(x).fdiff(2))
assert erfc(x).taylor_term(3, x, *(-2*x/sqrt(pi), 0)) == 2*x**3/3/sqrt(pi)
assert erfc(x).limit(x, oo) == 0
assert erfc(x).diff(x) == -2*exp(-x**2)/sqrt(pi)
def test_airyai():
z = Symbol('z', extended_real=False)
r = Symbol('r', extended_real=True)
t = Symbol('t', negative=True)
p = Symbol('p', positive=True)
assert isinstance(airyai(z), airyai)
assert airyai(0) == cbrt(3)/(3*gamma(Rational(2, 3)))
assert airyai(oo) == 0
assert airyai(-oo) == 0
assert diff(airyai(z), z) == airyaiprime(z)
assert airyai(z).series(z, 0, 3) == (
3**Rational(5, 6)*gamma(Rational(1, 3))/(6*pi) - root(3, 6)*z*gamma(Rational(2, 3))/(2*pi) + O(z**3))
l = Limit(airyai(I/x)/(exp(-Rational(2, 3)*(I/x)**Rational(3, 2))*sqrt(pi*sqrt(I/x))/2), x, 0)
assert l.doit() == l # cover _airyais._eval_aseries
assert airyai(z).rewrite(hyper) == (
-3**Rational(2, 3)*z*hyper((), (Rational(4, 3),), z**3/9)/(3*gamma(Rational(1, 3))) +
cbrt(3)*hyper((), (Rational(2, 3),), z**3/9)/(3*gamma(Rational(2, 3))))
assert isinstance(airyai(z).rewrite(besselj), airyai)
assert airyai(t).rewrite(besselj) == (
sqrt(-t)*(besselj(-Rational(1, 3), 2*(-t)**Rational(3, 2)/3) +
besselj(Rational(1, 3), 2*(-t)**Rational(3, 2)/3))/3)
assert airyai(z).rewrite(besseli) == (
-z*besseli(Rational(1, 3), 2*z**Rational(3, 2)/3)/(3*cbrt(z**Rational(3, 2))) +
cbrt(z**Rational(3, 2))*besseli(-Rational(1, 3), 2*z**Rational(3, 2)/3)/3)
assert airyai(p).rewrite(besseli) == (
sqrt(p)*(besseli(-Rational(1, 3), 2*p**Rational(3, 2)/3) -
besseli(Rational(1, 3), 2*p**Rational(3, 2)/3))/3)
assert expand_func(airyai(2*cbrt(3*z**5))) == (
-sqrt(3)*(-1 + cbrt(z**5)/z**Rational(5, 3))*airybi(2*cbrt(3)*z**Rational(5, 3))/6 +
(1 + cbrt(z**5)/z**Rational(5, 3))*airyai(2*cbrt(3)*z**Rational(5, 3))/2)
assert expand_func(airyai(x*y)) == airyai(x*y)
assert expand_func(airyai(log(x))) == airyai(log(x))
assert expand_func(airyai(2*root(3*z**5, 5))) == airyai(2*root(3*z**5, 5))
assert (airyai(r).as_real_imag() ==
airyai(r).as_real_imag(deep=False) == (airyai(r), 0))
assert airyai(x).as_real_imag() == airyai(x).as_real_imag(deep=False)
assert (airyai(x).as_real_imag() ==
(airyai(re(x) - I*re(x)*abs(im(x))/abs(re(x)))/2 +
airyai(re(x) + I*re(x)*abs(im(x))/abs(re(x)))/2,
I*(airyai(re(x) - I*re(x)*abs(im(x))/abs(re(x))) -
airyai(re(x) + I*re(x)*abs(im(x))/abs(re(x)))) *
re(x)*abs(im(x))/(2*im(x)*abs(re(x)))))
assert airyai(x).taylor_term(-1, x) == 0
def test_airyai():
z = Symbol('z', extended_real=False)
r = Symbol('r', extended_real=True)
t = Symbol('t', negative=True)
p = Symbol('p', positive=True)
assert isinstance(airyai(z), airyai)
assert airyai(0) == cbrt(3)/(3*gamma(Rational(2, 3)))
assert airyai(oo) == 0
assert airyai(-oo) == 0
assert diff(airyai(z), z) == airyaiprime(z)
assert series(airyai(z), z, 0, 3) == (
3**Rational(5, 6)*gamma(Rational(1, 3))/(6*pi) - root(3, 6)*z*gamma(Rational(2, 3))/(2*pi) + O(z**3))
l = Limit(airyai(I/x)/(exp(-Rational(2, 3)*(I/x)**Rational(3, 2))*sqrt(pi*sqrt(I/x))/2), x, 0)
assert l.doit() == l # cover _airyais._eval_aseries
assert airyai(z).rewrite(hyper) == (
-3**Rational(2, 3)*z*hyper((), (Rational(4, 3),), z**3/9)/(3*gamma(Rational(1, 3))) +
cbrt(3)*hyper((), (Rational(2, 3),), z**3/9)/(3*gamma(Rational(2, 3))))
assert isinstance(airyai(z).rewrite(besselj), airyai)
assert airyai(t).rewrite(besselj) == (
sqrt(-t)*(besselj(-Rational(1, 3), 2*(-t)**Rational(3, 2)/3) +
besselj(Rational(1, 3), 2*(-t)**Rational(3, 2)/3))/3)
assert airyai(z).rewrite(besseli) == (
-z*besseli(Rational(1, 3), 2*z**Rational(3, 2)/3)/(3*cbrt(z**Rational(3, 2))) +
cbrt(z**Rational(3, 2))*besseli(-Rational(1, 3), 2*z**Rational(3, 2)/3)/3)
assert airyai(p).rewrite(besseli) == (
sqrt(p)*(besseli(-Rational(1, 3), 2*p**Rational(3, 2)/3) -
besseli(Rational(1, 3), 2*p**Rational(3, 2)/3))/3)
assert expand_func(airyai(2*cbrt(3*z**5))) == (
-sqrt(3)*(-1 + cbrt(z**5)/z**Rational(5, 3))*airybi(2*cbrt(3)*z**Rational(5, 3))/6 +
(1 + cbrt(z**5)/z**Rational(5, 3))*airyai(2*cbrt(3)*z**Rational(5, 3))/2)
assert expand_func(airyai(x*y)) == airyai(x*y)
assert expand_func(airyai(log(x))) == airyai(log(x))
assert expand_func(airyai(2*root(3*z**5, 5))) == airyai(2*root(3*z**5, 5))
assert (airyai(r).as_real_imag() ==
airyai(r).as_real_imag(deep=False) == (airyai(r), 0))
assert airyai(x).as_real_imag() == airyai(x).as_real_imag(deep=False)
assert (airyai(x).as_real_imag() ==
(airyai(re(x) - I*re(x)*abs(im(x))/abs(re(x)))/2 +
airyai(re(x) + I*re(x)*abs(im(x))/abs(re(x)))/2,
I*(airyai(re(x) - I*re(x)*abs(im(x))/abs(re(x))) -
airyai(re(x) + I*re(x)*abs(im(x))/Abs(re(x)))) *
re(x)*abs(im(x))/(2*im(x)*abs(re(x)))))
assert airyai(x).taylor_term(-1, x) == 0
def test_catalan():
n = Symbol('n', integer=True)
m = Symbol('n', integer=True, positive=True)
catalans = [1, 1, 2, 5, 14, 42, 132, 429, 1430, 4862, 16796, 58786]
for i, c in enumerate(catalans):
assert catalan(i) == c
assert catalan(n).rewrite(factorial).subs({n: i}) == c
assert catalan(n).rewrite(Product).subs({n: i}).doit() == c
assert catalan(x) == catalan(x)
assert catalan(2 *
x).rewrite(binomial) == binomial(4 * x, 2 * x) / (2 * x + 1)
assert catalan(Rational(1, 2)).rewrite(gamma) == 8 / (3 * pi)
assert catalan(Rational(1, 2)).rewrite(factorial).rewrite(gamma) ==\
8 / (3 * pi)
assert catalan(3 * x).rewrite(gamma) == 4**(
3 * x) * gamma(3 * x + Rational(1, 2)) / (sqrt(pi) * gamma(3 * x + 2))
assert catalan(x).rewrite(hyper) == hyper((-x + 1, -x), (2, ), 1)
assert catalan(n).rewrite(factorial) == factorial(
2 * n) / (factorial(n + 1) * factorial(n))
assert isinstance(catalan(n).rewrite(Product), catalan)
assert isinstance(catalan(m).rewrite(Product), Product)
assert diff(catalan(x), x) == (polygamma(0, x + Rational(1, 2)) -
polygamma(0, x + 2) + log(4)) * catalan(x)
assert catalan(x).evalf() == catalan(x)
c = catalan(Rational(1, 2)).evalf()
assert str(c) == '0.848826363156775'
c = catalan(I).evalf(3)
assert sstr((re(c), im(c))) == '(0.398, -0.0209)'
# issue sympy/sympy#8601
n = Symbol('n', integer=True, negative=True)
assert catalan(n - 1) == 0
assert catalan(Rational(-1, 2)) == zoo
assert catalan(-1) == Rational(-1, 2)
c1 = catalan(-5.6).evalf(strict=False)
assert str(c1) == '6.93334070531408e-5'
c2 = catalan(-35.4).evalf(strict=False)
assert str(c2) == '-4.14189164517449e-24'
def test_erfi():
assert erfi(nan) == nan
assert erfi(+oo) == +oo
assert erfi(-oo) == -oo
assert erfi(0) == 0
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).is_extended_real is False
assert erfi(w).is_extended_real is True
assert erfi(z).is_extended_real is None
assert conjugate(erfi(z)) == erfi(conjugate(z))
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([Rational(1, 2)], [Rational(3, 2)], z**2)/sqrt(pi)
assert erfi(z).rewrite('meijerg') == z*meijerg([Rational(1, 2)], [], [0], [Rational(-1, 2)], -z**2)/sqrt(pi)
assert erfi(z).rewrite('uppergamma') == (sqrt(-z**2)/z*(uppergamma(Rational(1, 2),
-z**2)/sqrt(pi) - 1))
assert erfi(z).rewrite('expint') == sqrt(-z**2)/z - z*expint(Rational(1, 2), -z**2)/sqrt(pi)
assert erfi(x).as_real_imag() == \
((erfi(re(x) - I*re(x)*Abs(im(x))/Abs(re(x)))/2 +
erfi(re(x) + I*re(x)*Abs(im(x))/Abs(re(x)))/2,
I*(erfi(re(x) - I*re(x)*Abs(im(x))/Abs(re(x))) -
erfi(re(x) + I*re(x)*Abs(im(x))/Abs(re(x)))) *
re(x)*Abs(im(x))/(2*im(x)*Abs(re(x)))))
assert erfi(x).as_real_imag(deep=False) == erfi(x).as_real_imag()
assert erfi(w).as_real_imag() == (erfi(w), 0)
assert erfi(w).as_real_imag(deep=False) == erfi(w).as_real_imag()
assert erfi(I).as_real_imag() == (0, erf(1))
pytest.raises(ArgumentIndexError, lambda: erfi(x).fdiff(2))
assert erfi(x).taylor_term(3, x, *(2*x/sqrt(pi), 0)) == 2*x**3/3/sqrt(pi)
assert erfi(x).limit(x, oo) == oo
def test_derivatives_sympyissue_4757():
x = Symbol('x', extended_real=True)
y = Symbol('y', imaginary=True)
f = Function('f')
assert re(f(x)).diff(x) == re(f(x).diff(x))
assert im(f(x)).diff(x) == im(f(x).diff(x))
assert re(f(y)).diff(y) == -I*im(f(y).diff(y))
assert im(f(y)).diff(y) == -I*re(f(y).diff(y))
assert re(f(z)).diff(z) == Derivative(re(f(z)), z)
assert im(f(z)).diff(z) == Derivative(im(f(z)), z)
assert abs(f(x)).diff(x).subs({f(x): 1 + I*x}).doit() == x/sqrt(1 + x**2)
assert arg(f(x)).diff(x).subs({f(x): 1 + I*x**2}).doit() == 2*x/(1 + x**4)
assert abs(f(y)).diff(y).subs({f(y): 1 + y}).doit() == -y/sqrt(1 - y**2)
assert arg(f(y)).diff(y).subs({f(y): I + y**2}).doit() == 2*y/(1 + y**4)
def test_derivatives_sympyissue_4757():
x = Symbol('x', extended_real=True)
y = Symbol('y', imaginary=True)
f = Function('f')
assert re(f(x)).diff(x) == re(f(x).diff(x))
assert im(f(x)).diff(x) == im(f(x).diff(x))
assert re(f(y)).diff(y) == -I*im(f(y).diff(y))
assert im(f(y)).diff(y) == -I*re(f(y).diff(y))
assert re(f(z)).diff(z) == Derivative(re(f(z)), z)
assert im(f(z)).diff(z) == Derivative(im(f(z)), z)
assert Abs(f(x)).diff(x).subs({f(x): 1 + I*x}).doit() == x/sqrt(1 + x**2)
assert arg(f(x)).diff(x).subs({f(x): 1 + I*x**2}).doit() == 2*x/(1 + x**4)
assert Abs(f(y)).diff(y).subs({f(y): 1 + y}).doit() == -y/sqrt(1 - y**2)
assert arg(f(y)).diff(y).subs({f(y): I + y**2}).doit() == 2*y/(1 + y**4)
def test_erfi():
assert erfi(nan) == nan
assert erfi(oo) == S.Infinity
assert erfi(-oo) == S.NegativeInfinity
assert erfi(0) == 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).is_extended_real is False
assert erfi(w).is_extended_real is True
assert erfi(z).is_extended_real is None
assert conjugate(erfi(z)) == erfi(conjugate(z))
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], [-S.Half], -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(x).as_real_imag() == \
((erfi(re(x) - I*re(x)*Abs(im(x))/Abs(re(x)))/2 +
erfi(re(x) + I*re(x)*Abs(im(x))/Abs(re(x)))/2,
I*(erfi(re(x) - I*re(x)*Abs(im(x))/Abs(re(x))) -
erfi(re(x) + I*re(x)*Abs(im(x))/Abs(re(x)))) *
re(x)*Abs(im(x))/(2*im(x)*Abs(re(x)))))
pytest.raises(ArgumentIndexError, lambda: erfi(x).fdiff(2))
def test_erfc():
assert erfc(nan) == nan
assert erfc(oo) == 0
assert erfc(-oo) == 2
assert erfc(0) == 1
assert erfc(I * oo) == -oo * I
assert erfc(-I * oo) == oo * I
assert erfc(-x) == Integer(2) - erfc(x)
assert erfc(erfcinv(x)) == x
assert erfc(I).is_extended_real is False
assert erfc(w).is_extended_real is True
assert erfc(z).is_extended_real is None
assert conjugate(erfc(z)) == erfc(conjugate(z))
assert erfc(x).as_leading_term(x) == S.One
assert erfc(1 / x).as_leading_term(x) == erfc(1 / x)
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], [-S.Half], z**2) / sqrt(pi)
assert erfc(z).rewrite(
'uppergamma') == 1 - sqrt(z**2) * erf(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(x).as_real_imag() == \
((erfc(re(x) - I*re(x)*Abs(im(x))/Abs(re(x)))/2 +
erfc(re(x) + I*re(x)*Abs(im(x))/Abs(re(x)))/2,
I*(erfc(re(x) - I*re(x)*Abs(im(x))/Abs(re(x))) -
erfc(re(x) + I*re(x)*Abs(im(x))/Abs(re(x)))) *
re(x)*Abs(im(x))/(2*im(x)*Abs(re(x)))))
pytest.raises(ArgumentIndexError, lambda: erfc(x).fdiff(2))
def test_sympyissue_5084():
assert ((x + x * I) / (1 + I)).as_real_imag() == (re(
(x + I * x) / (1 + I)), im((x + I * x) / (1 + I)))
def test_im():
a, b = symbols('a,b', extended_real=True)
r = Symbol('r', extended_real=True)
i = Symbol('i', imaginary=True)
assert im(nan) == nan
assert im(oo*I) == oo
assert im(-oo*I) == -oo
assert im(0) == 0
assert im(1) == 0
assert im(-1) == 0
assert im(E*I) == E
assert im(-E*I) == -E
assert im(x) == im(x)
assert im(x*I) == re(x)
assert im(r*I) == r
assert im(r) == 0
assert im(i*I) == 0
assert im(i) == -I * i
assert im(x + y) == im(x + y)
assert im(x + r) == im(x)
assert im(x + r*I) == im(x) + r
assert im(im(x)*I) == im(x)
assert im(2 + I) == 1
assert im(x + I) == im(x) + 1
assert im(x + y*I) == im(x) + re(y)
assert im(x + r*I) == im(x) + r
assert im(log(2*I)) == pi/2
assert im((2 + I)**2).expand(complex=True) == 4
assert im(conjugate(x)) == -im(x)
assert conjugate(im(x)) == im(x)
assert im(x).as_real_imag() == (im(x), 0)
assert im(i*r*x).diff(r) == im(i*x)
assert im(i*r*x).diff(i) == -I * re(r*x)
assert im(sqrt(a + b*I)) == root(a**2 + b**2, 4)*sin(arg(a + I*b)/2)
assert im(a * (2 + b*I)) == a*b
assert im((1 + sqrt(a + b*I))/2) == root(a**2 + b**2, 4)*sin(arg(a + I*b)/2)/2
assert im(x).rewrite(re) == -I*(x - re(x)) # sympy/sympy#10897
assert (x + im(y)).rewrite(im, re) == x - I*(y - re(y))
a = Symbol('a', algebraic=True)
t = Symbol('t', transcendental=True)
assert re(a).is_algebraic
assert re(x).is_algebraic is None
assert re(t).is_algebraic is False
assert re(zoo) == nan
def test_real_imag():
x, y, z = symbols('x, y, z')
X, Y, Z = symbols('X, Y, Z', commutative=False)
a = Symbol('a', extended_real=True)
assert (2*a*x).as_real_imag() == (2*a*re(x), 2*a*im(x))
# issue sympy/sympy#5395:
assert (x*x.conjugate()).as_real_imag() == (Abs(x)**2, 0)
assert im(x*x.conjugate()) == 0
assert im(x*y.conjugate()*z*y) == im(x*z)*Abs(y)**2
assert im(x*y.conjugate()*x*y) == im(x**2)*Abs(y)**2
assert im(Z*y.conjugate()*X*y) == im(Z*X)*Abs(y)**2
assert im(X*X.conjugate()) == im(X*X.conjugate(), evaluate=False)
assert (sin(x)*sin(x).conjugate()).as_real_imag() == \
(Abs(sin(x))**2, 0)
# issue sympy/sympy#6573:
assert (x**2).as_real_imag() == (re(x)**2 - im(x)**2, 2*re(x)*im(x))
# issue sympy/sympy#6428:
r = Symbol('r', extended_real=True)
i = Symbol('i', imaginary=True)
assert (i*r*x).as_real_imag() == (I*i*r*im(x), -I*i*r*re(x))
assert (i*r*x*(y + 2)).as_real_imag() == (
I*i*r*(re(y) + 2)*im(x) + I*i*r*re(x)*im(y),
-I*i*r*(re(y) + 2)*re(x) + I*i*r*im(x)*im(y))
# issue sympy/sympy#7106:
assert ((1 + I)/(1 - I)).as_real_imag() == (0, 1)
assert ((1 + 2*I)*(1 + 3*I)).as_real_imag() == (-5, 5)
assert exp(x).as_real_imag(deep=False) == (re(exp(x)), im(exp(x)))
assert (2**x).as_real_imag(deep=False) == (re(2**x), im(2**x))
def as_real_imag(self, deep=True, **hints):
from diofant import im, re
if hints.get('ignore') == self:
return
else:
return re(self), im(self)
def test_im():
a, b = symbols('a,b', extended_real=True)
r = Symbol('r', extended_real=True)
i = Symbol('i', imaginary=True)
assert im(nan) == nan
assert im(oo*I) == oo
assert im(-oo*I) == -oo
assert im(0) == 0
assert im(1) == 0
assert im(-1) == 0
assert im(E*I) == E
assert im(-E*I) == -E
assert im(x) == im(x)
assert im(x*I) == re(x)
assert im(r*I) == r
assert im(r) == 0
assert im(i*I) == 0
assert im(i) == -I * i
assert im(x + y) == im(x + y)
assert im(x + r) == im(x)
assert im(x + r*I) == im(x) + r
assert im(im(x)*I) == im(x)
assert im(2 + I) == 1
assert im(x + I) == im(x) + 1
assert im(x + y*I) == im(x) + re(y)
assert im(x + r*I) == im(x) + r
assert im(log(2*I)) == pi/2
assert im((2 + I)**2).expand(complex=True) == 4
assert im(conjugate(x)) == -im(x)
assert conjugate(im(x)) == im(x)
assert im(x).as_real_imag() == (im(x), 0)
assert im(i*r*x).diff(r) == im(i*x)
assert im(i*r*x).diff(i) == -I * re(r*x)
assert im(sqrt(a + b*I)) == root(a**2 + b**2, 4)*sin(arg(a + I*b)/2)
assert im(a * (2 + b*I)) == a*b
assert im((1 + sqrt(a + b*I))/2) == root(a**2 + b**2, 4)*sin(arg(a + I*b)/2)/2
assert im(x).rewrite(re) == -I*(x - re(x)) # sympy/sympy#10897
assert (x + im(y)).rewrite(im, re) == x - I*(y - re(y))
a = Symbol('a', algebraic=True)
t = Symbol('t', transcendental=True)
assert re(a).is_algebraic
assert re(x).is_algebraic is None
assert re(t).is_algebraic is False
assert re(zoo) == nan
def test_re():
a, b = symbols('a,b', extended_real=True)
r = Symbol('r', extended_real=True)
i = Symbol('i', imaginary=True)
assert re(nan) == nan
assert re(oo) == oo
assert re(-oo) == -oo
assert re(0) == 0
assert re(1) == 1
assert re(-1) == -1
assert re(E) == E
assert re(-E) == -E
assert re(x) == re(x)
assert re(x*I) == -im(x)
assert re(r*I) == 0
assert re(r) == r
assert re(i*I) == I * i
assert re(i) == 0
assert re(x + y) == re(x + y)
assert re(x + r) == re(x) + r
assert re(re(x)) == re(x)
assert re(2 + I) == 2
assert re(x + I) == re(x)
assert re(x + y*I) == re(x) - im(y)
assert re(x + r*I) == re(x)
assert re(log(2*I)) == log(2)
assert re((2 + I)**2).expand(complex=True) == 3
assert re(conjugate(x)) == re(x)
assert conjugate(re(x)) == re(x)
assert re(x).as_real_imag() == (re(x), 0)
assert re(i*r*x).diff(r) == re(i*x)
assert re(i*r*x).diff(i) == I*r*im(x)
assert re(sqrt(a + b*I)) == root(a**2 + b**2, 4)*cos(arg(a + I*b)/2)
assert re(a * (2 + b*I)) == 2*a
assert re((1 + sqrt(a + b*I))/2) == root(a**2 + b**2, 4)*cos(arg(a + I*b)/2)/2 + Rational(1, 2)
assert re(x).rewrite(im) == x - I*im(x) # issue sympy/sympy#10897
assert (x + re(y)).rewrite(re, im) == x + y - I*im(y)
a = Symbol('a', algebraic=True)
t = Symbol('t', transcendental=True)
assert re(a).is_algebraic
assert re(x).is_algebraic is None
assert re(t).is_algebraic is False
assert re(zoo) == nan
def test_fresnel():
assert fresnels(0) == 0
assert fresnels(+oo) == Rational(+1, 2)
assert fresnels(-oo) == Rational(-1, 2)
assert fresnels(z) == fresnels(z)
assert fresnels(-z) == -fresnels(z)
assert fresnels(I * z) == -I * fresnels(z)
assert fresnels(-I * z) == I * fresnels(z)
assert conjugate(fresnels(z)) == fresnels(conjugate(z))
assert fresnels(z).diff(z) == sin(pi * z**2 / 2)
assert fresnels(z).rewrite(erf) == (1 + I) / 4 * (erf(
(1 + I) / 2 * sqrt(pi) * z) - I * erf((1 - I) / 2 * sqrt(pi) * z))
assert fresnels(z).rewrite(hyper) == \
pi*z**3/6 * hyper([Rational(3, 4)], [Rational(3, 2), Rational(7, 4)], -pi**2*z**4/16)
assert fresnels(z).series(z, n=15) == \
pi*z**3/6 - pi**3*z**7/336 + pi**5*z**11/42240 + O(z**15)
assert fresnels(y / z).limit(z, 0) == fresnels(oo * sign(y))
assert fresnels(x).taylor_term(-1, z) == 0
assert fresnels(x).taylor_term(1, z,
*(pi * z**3 / 6, )) == -pi**3 * z**7 / 336
assert fresnels(x).taylor_term(1, z) == -pi**3 * z**7 / 336
assert fresnels(w).is_extended_real is True
assert fresnels(z).is_extended_real is None
assert fresnels(z).as_real_imag() == \
((fresnels(re(z) - I*re(z)*abs(im(z))/abs(re(z)))/2 +
fresnels(re(z) + I*re(z)*abs(im(z))/abs(re(z)))/2,
I*(fresnels(re(z) - I*re(z)*abs(im(z))/abs(re(z))) -
fresnels(re(z) + I*re(z)*abs(im(z))/abs(re(z)))) *
re(z)*abs(im(z))/(2*im(z)*abs(re(z)))))
assert fresnels(z).as_real_imag(deep=False) == fresnels(z).as_real_imag()
assert fresnels(w).as_real_imag() == (fresnels(w), 0)
assert fresnels(w).as_real_imag(deep=False) == fresnels(w).as_real_imag()
assert (fresnels(I, evaluate=False).as_real_imag() == (
0, -erf(sqrt(pi) / 2 + I * sqrt(pi) / 2) / 4 + I *
(-erf(sqrt(pi) / 2 + I * sqrt(pi) / 2) +
erf(sqrt(pi) / 2 - I * sqrt(pi) / 2)) / 4 -
erf(sqrt(pi) / 2 - I * sqrt(pi) / 2) / 4))
assert fresnels(2 + 3 * I).as_real_imag() == (
fresnels(2 + 3 * I) / 2 + fresnels(2 - 3 * I) / 2,
I * (fresnels(2 - 3 * I) - fresnels(2 + 3 * I)) / 2)
assert expand_func(integrate(fresnels(z), z)) == \
z*fresnels(z) + cos(pi*z**2/2)/pi
assert fresnels(z).rewrite(meijerg) == sqrt(2)*pi*z**Rational(9, 4) * \
meijerg(((), (1,)), ((Rational(3, 4),),
(Rational(1, 4), 0)), -pi**2*z**4/16)/(2*(-z)**Rational(3, 4)*(z**2)**Rational(3, 4))
assert fresnelc(0) == 0
assert fresnelc(+oo) == Rational(+1, 2)
assert fresnelc(-oo) == Rational(-1, 2)
assert fresnelc(z) == fresnelc(z)
assert fresnelc(-z) == -fresnelc(z)
assert fresnelc(I * z) == I * fresnelc(z)
assert fresnelc(-I * z) == -I * fresnelc(z)
assert conjugate(fresnelc(z)) == fresnelc(conjugate(z))
assert fresnelc(z).diff(z) == cos(pi * z**2 / 2)
pytest.raises(ArgumentIndexError, lambda: fresnels(z).fdiff(2))
pytest.raises(ArgumentIndexError, lambda: fresnelc(z).fdiff(2))
assert fresnelc(z).rewrite(erf) == (1 - I) / 4 * (erf(
(1 + I) / 2 * sqrt(pi) * z) + I * erf((1 - I) / 2 * sqrt(pi) * z))
assert fresnelc(z).rewrite(hyper) == \
z * hyper([Rational(1, 4)], [Rational(1, 2), Rational(5, 4)], -pi**2*z**4/16)
assert fresnelc(x).taylor_term(-1, z) == 0
assert fresnelc(x).taylor_term(1, z, *(z, )) == -pi**2 * z**5 / 40
assert fresnelc(x).taylor_term(1, z) == -pi**2 * z**5 / 40
assert fresnelc(z).series(z, n=15) == \
z - pi**2*z**5/40 + pi**4*z**9/3456 - pi**6*z**13/599040 + O(z**15)
assert fresnelc(y / z).limit(z, 0) == fresnelc(oo * sign(y))
# issue sympy/sympy#6510
assert fresnels(z).series(z, oo) == \
(-1/(pi**2*z**3) + O(z**(-6), (z, oo)))*sin(pi*z**2/2) + \
(3/(pi**3*z**5) - 1/(pi*z) + O(z**(-6), (z, oo)))*cos(pi*z**2/2) + Rational(1, 2)
assert fresnelc(z).series(z, oo) == \
(-1/(pi**2*z**3) + O(z**(-6), (z, oo)))*cos(pi*z**2/2) + \
(-3/(pi**3*z**5) + 1/(pi*z) + O(z**(-6), (z, oo)))*sin(pi*z**2/2) + Rational(1, 2)
assert fresnels(1/z).series(z) == \
(-z**3/pi**2 + O(z**6))*sin(pi/(2*z**2)) + (-z/pi + 3*z**5/pi**3 +
O(z**6))*cos(pi/(2*z**2)) + Rational(1, 2)
assert fresnelc(1/z).series(z) == \
(-z**3/pi**2 + O(z**6))*cos(pi/(2*z**2)) + (z/pi - 3*z**5/pi**3 +
O(z**6))*sin(pi/(2*z**2)) + Rational(1, 2)
assert fresnelc(w).is_extended_real is True
assert fresnelc(z).as_real_imag() == \
((fresnelc(re(z) - I*re(z)*abs(im(z))/abs(re(z)))/2 +
fresnelc(re(z) + I*re(z)*abs(im(z))/abs(re(z)))/2,
I*(fresnelc(re(z) - I*re(z)*abs(im(z))/abs(re(z))) -
fresnelc(re(z) + I*re(z)*abs(im(z))/abs(re(z)))) *
re(z)*abs(im(z))/(2*im(z)*abs(re(z)))))
assert fresnelc(2 + 3 * I).as_real_imag() == (
fresnelc(2 - 3 * I) / 2 + fresnelc(2 + 3 * I) / 2,
I * (fresnelc(2 - 3 * I) - fresnelc(2 + 3 * I)) / 2)
assert expand_func(integrate(fresnelc(z), z)) == \
z*fresnelc(z) - sin(pi*z**2/2)/pi
assert fresnelc(z).rewrite(meijerg) == sqrt(2)*pi*z**Rational(3, 4) * \
meijerg(((), (1,)), ((Rational(1, 4),),
(Rational(3, 4), 0)), -pi**2*z**4/16)/(2*root(-z, 4)*root(z**2, 4))
verify_numerically(re(fresnels(z)), fresnels(z).as_real_imag()[0], z)
verify_numerically(im(fresnels(z)), fresnels(z).as_real_imag()[1], z)
verify_numerically(fresnels(z), fresnels(z).rewrite(hyper), z)
verify_numerically(fresnels(z), fresnels(z).rewrite(meijerg), z)
verify_numerically(re(fresnelc(z)), fresnelc(z).as_real_imag()[0], z)
verify_numerically(im(fresnelc(z)), fresnelc(z).as_real_imag()[1], z)
verify_numerically(fresnelc(z), fresnelc(z).rewrite(hyper), z)
verify_numerically(fresnelc(z), fresnelc(z).rewrite(meijerg), z)
def test_re_im1652():
assert re(x) == re(conjugate(x))
assert im(x) == -im(conjugate(x))
assert im(x) * re(conjugate(x)) + im(conjugate(x)) * re(x) == 0
def test_sympyissue_7450():
ans = integrate(exp(-(1 + I)*x), (x, 0, oo))
assert re(ans) == Rational(1, 2) and im(ans) == Rational(-1, 2)
def test_erf():
assert erf(nan) == nan
assert erf(oo) == 1
assert erf(-oo) == -1
assert erf(0) == 0
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, erf(erfcinv(1 - erf(erfinv(x)))))) == x
assert erf(I).is_extended_real is False
assert erf(w).is_extended_real is True
assert erf(z).is_extended_real is None
assert conjugate(erf(z)) == erf(conjugate(z))
assert erf(x).as_leading_term(x) == 2 * x / sqrt(pi)
assert erf(1 / x).as_leading_term(x) == erf(1 / x)
assert erf(z).rewrite('uppergamma') == sqrt(z**2) * erf(sqrt(z**2)) / z
assert erf(z).rewrite('erfc') == 1 - 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(
[Rational(1, 2)], [Rational(3, 2)], -z**2) / sqrt(pi)
assert erf(z).rewrite('meijerg') == z * meijerg(
[Rational(1, 2)], [], [0], [Rational(-1, 2)], z**2) / sqrt(pi)
assert erf(z).rewrite('expint') == sqrt(z**2) / z - z * expint(
Rational(1, 2), z**2) / sqrt(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
l = Limit((1 - erf(y / x)) * exp(y**2 / x**2), x, 0)
assert l.doit() == l # cover _erfs._eval_aseries
assert erf(x).as_real_imag() == \
((erf(re(x) - I*re(x)*abs(im(x))/abs(re(x)))/2 +
erf(re(x) + I*re(x)*abs(im(x))/abs(re(x)))/2,
I*(erf(re(x) - I*re(x)*abs(im(x))/abs(re(x))) -
erf(re(x) + I*re(x)*abs(im(x))/abs(re(x)))) *
re(x)*abs(im(x))/(2*im(x)*abs(re(x)))))
assert erf(x).as_real_imag() == erf(x).as_real_imag(deep=False)
assert erf(w).as_real_imag() == (erf(w), 0)
assert erf(w).as_real_imag() == erf(w).as_real_imag(deep=False)
assert erf(I).as_real_imag() == (0, erfi(1))
pytest.raises(ArgumentIndexError, lambda: erf(x).fdiff(2))
assert erf(x).taylor_term(3, x, *(2 * x / sqrt(pi),
0)) == -2 * x**3 / 3 / sqrt(pi)
def test_real_imag():
X, Z = symbols('X Z', commutative=False)
a = Symbol('a', extended_real=True)
assert (2 * a * x).as_real_imag() == (2 * a * re(x), 2 * a * im(x))
# issue sympy/sympy#5395:
assert (x * x.conjugate()).as_real_imag() == (abs(x)**2, 0)
assert im(x * x.conjugate()) == 0
assert im(x * y.conjugate() * z * y) == im(x * z) * abs(y)**2
assert im(x * y.conjugate() * x * y) == im(x**2) * abs(y)**2
assert im(Z * y.conjugate() * X * y) == im(Z * X) * abs(y)**2
assert im(X * X.conjugate()) == im(X * X.conjugate(), evaluate=False)
assert (sin(x)*sin(x).conjugate()).as_real_imag() == \
(abs(sin(x))**2, 0)
# issue sympy/sympy#6573:
assert (x**2).as_real_imag() == (re(x)**2 - im(x)**2, 2 * re(x) * im(x))
# issue sympy/sympy#6428:
r = Symbol('r', extended_real=True)
i = Symbol('i', imaginary=True)
assert (i * r * x).as_real_imag() == (I * i * r * im(x),
-I * i * r * re(x))
assert (i * r * x *
(y + 2)).as_real_imag() == (I * i * r * (re(y) + 2) * im(x) +
I * i * r * re(x) * im(y),
-I * i * r * (re(y) + 2) * re(x) +
I * i * r * im(x) * im(y))
# issue sympy/sympy#7106:
assert ((1 + I) / (1 - I)).as_real_imag() == (0, 1)
assert ((1 + 2 * I) * (1 + 3 * I)).as_real_imag() == (-5, 5)
assert exp(x).as_real_imag(deep=False) == (re(exp(x)), im(exp(x)))
assert (2**x).as_real_imag(deep=False) == (re(2**x), im(2**x))
def test_sign():
assert sign(1.2) == 1
assert sign(-1.2) == -1
assert sign(3*I) == I
assert sign(-3*I) == -I
assert sign(0) == 0
assert sign(nan) == nan
assert sign(2 + 2*I).doit() == sqrt(2)*(2 + 2*I)/4
assert sign(2 + 3*I).simplify() == sign(2 + 3*I)
assert sign(2 + 2*I).simplify() == sign(1 + I)
assert sign(im(sqrt(1 - sqrt(3)))) == 1
assert sign(sqrt(1 - sqrt(3))) == I
x = Symbol('x')
assert sign(x).is_finite is True
assert sign(x).is_complex is True
assert sign(x).is_imaginary is None
assert sign(x).is_integer is None
assert sign(x).is_extended_real is None
assert sign(x).is_zero is None
assert sign(x).doit() == sign(x)
assert sign(1.2*x) == sign(x)
assert sign(2*x) == sign(x)
assert sign(I*x) == I*sign(x)
assert sign(-2*I*x) == -I*sign(x)
assert sign(conjugate(x)) == conjugate(sign(x))
p = Symbol('p', positive=True)
n = Symbol('n', negative=True)
m = Symbol('m', negative=True)
assert sign(2*p*x) == sign(x)
assert sign(n*x) == -sign(x)
assert sign(n*m*x) == sign(x)
x = Symbol('x', imaginary=True)
xn = Symbol('xn', imaginary=True, nonzero=True)
assert sign(x).is_imaginary is True
assert sign(x).is_integer is None
assert sign(x).is_extended_real is None
assert sign(x).is_zero is None
assert sign(x).diff(x) == 2*DiracDelta(-I*x)
assert sign(xn).doit() == xn / Abs(xn)
assert conjugate(sign(x)) == -sign(x)
x = Symbol('x', extended_real=True)
assert sign(x).is_imaginary is None
assert sign(x).is_integer is True
assert sign(x).is_extended_real is True
assert sign(x).is_zero is None
assert sign(x).diff(x) == 2*DiracDelta(x)
assert sign(x).doit() == sign(x)
assert conjugate(sign(x)) == sign(x)
assert sign(sin(x)).nseries(x) == 1
y = Symbol('y')
assert sign(x*y).nseries(x).removeO() == sign(y)
x = Symbol('x', nonzero=True)
assert sign(x).is_imaginary is None
assert sign(x).is_integer is None
assert sign(x).is_extended_real is None
assert sign(x).is_zero is False
assert sign(x).doit() == x / Abs(x)
assert sign(Abs(x)) == 1
assert Abs(sign(x)) == 1
x = Symbol('x', positive=True)
assert sign(x).is_imaginary is False
assert sign(x).is_integer is True
assert sign(x).is_extended_real is True
assert sign(x).is_zero is False
assert sign(x).doit() == x / Abs(x)
assert sign(Abs(x)) == 1
assert Abs(sign(x)) == 1
x = 0
assert sign(x).is_imaginary is True
assert sign(x).is_integer is True
assert sign(x).is_extended_real is True
assert sign(x).is_zero is True
assert sign(x).doit() == 0
assert sign(Abs(x)) == 0
assert Abs(sign(x)) == 0
nz = Symbol('nz', nonzero=True, integer=True)
assert sign(nz).is_imaginary is False
assert sign(nz).is_integer is True
assert sign(nz).is_extended_real is True
assert sign(nz).is_zero is False
assert sign(nz)**2 == 1
assert (sign(nz)**3).args == (sign(nz), 3)
assert sign(Symbol('x', nonnegative=True)).is_nonnegative
assert sign(Symbol('x', nonnegative=True)).is_nonpositive is None
assert sign(Symbol('x', nonpositive=True)).is_nonnegative is None
assert sign(Symbol('x', nonpositive=True)).is_nonpositive
assert sign(Symbol('x', extended_real=True)).is_nonnegative is None
assert sign(Symbol('x', extended_real=True)).is_nonpositive is None
assert sign(Symbol('x', extended_real=True, zero=False)).is_nonpositive is None
x, y = Symbol('x', extended_real=True), Symbol('y')
assert sign(x).rewrite(Piecewise) == \
Piecewise((1, x > 0), (-1, x < 0), (0, True))
assert sign(y).rewrite(Piecewise) == sign(y)
assert sign(x).rewrite(Heaviside) == 2*Heaviside(x)-1
assert sign(y).rewrite(Heaviside) == sign(y)
# evaluate what can be evaluated
assert sign(exp_polar(I*pi)*pi) is Integer(-1)
eq = -sqrt(10 + 6*sqrt(3)) + sqrt(1 + sqrt(3)) + sqrt(3 + 3*sqrt(3))
# if there is a fast way to know when and when you cannot prove an
# expression like this is zero then the equality to zero is ok
assert sign(eq) == 0
q = 1 + sqrt(2) - 2*sqrt(3) + 1331*sqrt(6)
p = cbrt(expand(q**3))
d = p - q
assert sign(d) == 0
assert abs(sign(z)) == Abs(sign(z), evaluate=False)
def test_erf():
assert erf(nan) == nan
assert erf(oo) == 1
assert erf(-oo) == -1
assert erf(0) == 0
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, erf(erfcinv(1 - erf(erfinv(x)))))) == x
assert erf(I).is_extended_real is False
assert erf(w).is_extended_real is True
assert erf(z).is_extended_real is None
assert conjugate(erf(z)) == erf(conjugate(z))
assert erf(x).as_leading_term(x) == 2*x/sqrt(pi)
assert erf(1/x).as_leading_term(x) == erf(1/x)
assert erf(z).rewrite('uppergamma') == sqrt(z**2)*erf(sqrt(z**2))/z
assert erf(z).rewrite('erfc') == 1 - 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([Rational(1, 2)], [Rational(3, 2)], -z**2)/sqrt(pi)
assert erf(z).rewrite('meijerg') == z*meijerg([Rational(1, 2)], [], [0], [Rational(-1, 2)], z**2)/sqrt(pi)
assert erf(z).rewrite('expint') == sqrt(z**2)/z - z*expint(Rational(1, 2), z**2)/sqrt(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
l = Limit((1 - erf(y/x))*exp(y**2/x**2), x, 0)
assert l.doit() == l # cover _erfs._eval_aseries
assert erf(x).as_real_imag() == \
((erf(re(x) - I*re(x)*Abs(im(x))/Abs(re(x)))/2 +
erf(re(x) + I*re(x)*Abs(im(x))/Abs(re(x)))/2,
I*(erf(re(x) - I*re(x)*Abs(im(x))/Abs(re(x))) -
erf(re(x) + I*re(x)*Abs(im(x))/Abs(re(x)))) *
re(x)*Abs(im(x))/(2*im(x)*Abs(re(x)))))
assert erf(x).as_real_imag() == erf(x).as_real_imag(deep=False)
assert erf(w).as_real_imag() == (erf(w), 0)
assert erf(w).as_real_imag() == erf(w).as_real_imag(deep=False)
assert erf(I).as_real_imag() == (0, erfi(1))
pytest.raises(ArgumentIndexError, lambda: erf(x).fdiff(2))
assert erf(x).taylor_term(3, x, *(2*x/sqrt(pi), 0)) == -2*x**3/3/sqrt(pi)
def test_sign():
assert sign(1.2) == 1
assert sign(-1.2) == -1
assert sign(3*I) == I
assert sign(-3*I) == -I
assert sign(0) == 0
assert sign(nan) == nan
assert sign(2 + 2*I).doit() == sqrt(2)*(2 + 2*I)/4
assert sign(2 + 3*I).simplify() == sign(2 + 3*I)
assert sign(2 + 2*I).simplify() == sign(1 + I)
assert sign(im(sqrt(1 - sqrt(3)))) == 1
assert sign(sqrt(1 - sqrt(3))) == I
x = Symbol('x')
assert sign(x).is_finite is True
assert sign(x).is_complex is True
assert sign(x).is_imaginary is None
assert sign(x).is_integer is None
assert sign(x).is_extended_real is None
assert sign(x).is_zero is None
assert sign(x).doit() == sign(x)
assert sign(1.2*x) == sign(x)
assert sign(2*x) == sign(x)
assert sign(I*x) == I*sign(x)
assert sign(-2*I*x) == -I*sign(x)
assert sign(conjugate(x)) == conjugate(sign(x))
p = Symbol('p', positive=True)
n = Symbol('n', negative=True)
m = Symbol('m', negative=True)
assert sign(2*p*x) == sign(x)
assert sign(n*x) == -sign(x)
assert sign(n*m*x) == sign(x)
x = Symbol('x', imaginary=True)
xn = Symbol('xn', imaginary=True, nonzero=True)
assert sign(x).is_imaginary is True
assert sign(x).is_integer is None
assert sign(x).is_extended_real is None
assert sign(x).is_zero is None
assert sign(x).diff(x) == 2*DiracDelta(-I*x)
assert sign(xn).doit() == xn / Abs(xn)
assert conjugate(sign(x)) == -sign(x)
x = Symbol('x', extended_real=True)
assert sign(x).is_imaginary is None
assert sign(x).is_integer is True
assert sign(x).is_extended_real is True
assert sign(x).is_zero is None
assert sign(x).diff(x) == 2*DiracDelta(x)
assert sign(x).doit() == sign(x)
assert conjugate(sign(x)) == sign(x)
assert sign(sin(x)).nseries(x) == 1
y = Symbol('y')
assert sign(x*y).nseries(x).removeO() == sign(y)
x = Symbol('x', nonzero=True)
assert sign(x).is_imaginary is None
assert sign(x).is_integer is None
assert sign(x).is_extended_real is None
assert sign(x).is_zero is False
assert sign(x).doit() == x / Abs(x)
assert sign(Abs(x)) == 1
assert Abs(sign(x)) == 1
x = Symbol('x', positive=True)
assert sign(x).is_imaginary is False
assert sign(x).is_integer is True
assert sign(x).is_extended_real is True
assert sign(x).is_zero is False
assert sign(x).doit() == x / Abs(x)
assert sign(Abs(x)) == 1
assert Abs(sign(x)) == 1
x = 0
assert sign(x).is_imaginary is True
assert sign(x).is_integer is True
assert sign(x).is_extended_real is True
assert sign(x).is_zero is True
assert sign(x).doit() == 0
assert sign(Abs(x)) == 0
assert Abs(sign(x)) == 0
nz = Symbol('nz', nonzero=True, integer=True)
assert sign(nz).is_imaginary is False
assert sign(nz).is_integer is True
assert sign(nz).is_extended_real is True
assert sign(nz).is_zero is False
assert sign(nz)**2 == 1
assert (sign(nz)**3).args == (sign(nz), 3)
assert sign(Symbol('x', nonnegative=True)).is_nonnegative
assert sign(Symbol('x', nonnegative=True)).is_nonpositive is None
assert sign(Symbol('x', nonpositive=True)).is_nonnegative is None
assert sign(Symbol('x', nonpositive=True)).is_nonpositive
assert sign(Symbol('x', extended_real=True)).is_nonnegative is None
assert sign(Symbol('x', extended_real=True)).is_nonpositive is None
assert sign(Symbol('x', extended_real=True, zero=False)).is_nonpositive is None
x, y = Symbol('x', extended_real=True), Symbol('y')
assert sign(x).rewrite(Piecewise) == \
Piecewise((1, x > 0), (-1, x < 0), (0, True))
assert sign(y).rewrite(Piecewise) == sign(y)
assert sign(x).rewrite(Heaviside) == 2*Heaviside(x)-1
assert sign(y).rewrite(Heaviside) == sign(y)
# evaluate what can be evaluated
assert sign(exp_polar(I*pi)*pi) is Integer(-1)
eq = -sqrt(10 + 6*sqrt(3)) + sqrt(1 + sqrt(3)) + sqrt(3 + 3*sqrt(3))
# if there is a fast way to know when and when you cannot prove an
# expression like this is zero then the equality to zero is ok
assert sign(eq) == 0
q = 1 + sqrt(2) - 2*sqrt(3) + 1331*sqrt(6)
p = cbrt(expand(q**3))
d = p - q
assert sign(d) == 0
assert abs(sign(z)) == Abs(sign(z), evaluate=False)
def test_re():
a, b = symbols('a,b', extended_real=True)
r = Symbol('r', extended_real=True)
i = Symbol('i', imaginary=True)
assert re(nan) == nan
assert re(oo) == oo
assert re(-oo) == -oo
assert re(0) == 0
assert re(1) == 1
assert re(-1) == -1
assert re(E) == E
assert re(-E) == -E
assert re(x) == re(x)
assert re(x*I) == -im(x)
assert re(r*I) == 0
assert re(r) == r
assert re(i*I) == I * i
assert re(i) == 0
assert re(x + y) == re(x + y)
assert re(x + r) == re(x) + r
assert re(re(x)) == re(x)
assert re(2 + I) == 2
assert re(x + I) == re(x)
assert re(x + y*I) == re(x) - im(y)
assert re(x + r*I) == re(x)
assert re(log(2*I)) == log(2)
assert re((2 + I)**2).expand(complex=True) == 3
assert re(conjugate(x)) == re(x)
assert conjugate(re(x)) == re(x)
assert re(x).as_real_imag() == (re(x), 0)
assert re(i*r*x).diff(r) == re(i*x)
assert re(i*r*x).diff(i) == I*r*im(x)
assert re(sqrt(a + b*I)) == root(a**2 + b**2, 4)*cos(arg(a + I*b)/2)
assert re(a * (2 + b*I)) == 2*a
assert re((1 + sqrt(a + b*I))/2) == root(a**2 + b**2, 4)*cos(arg(a + I*b)/2)/2 + Rational(1, 2)
assert re(x).rewrite(im) == x - I*im(x) # issue sympy/sympy#10897
assert (x + re(y)).rewrite(re, im) == x + y - I*im(y)
a = Symbol('a', algebraic=True)
t = Symbol('t', transcendental=True)
assert re(a).is_algebraic
assert re(x).is_algebraic is None
assert re(t).is_algebraic is False
assert re(zoo) == nan
def test_expand_function():
assert expand(x + y) == x + y
assert expand(x + y, complex=True) == I*im(x) + I*im(y) + re(x) + re(y)
assert expand((x + y)**11, modulus=11) == x**11 + y**11
def test_re_im1652():
x = Symbol('x')
assert re(x) == re(conjugate(x))
assert im(x) == - im(conjugate(x))
assert im(x)*re(conjugate(x)) + im(conjugate(x)) * re(x) == 0
def test_fresnel():
assert fresnels(0) == 0
assert fresnels(+oo) == Rational(+1, 2)
assert fresnels(-oo) == Rational(-1, 2)
assert fresnels(z) == fresnels(z)
assert fresnels(-z) == -fresnels(z)
assert fresnels(I*z) == -I*fresnels(z)
assert fresnels(-I*z) == I*fresnels(z)
assert conjugate(fresnels(z)) == fresnels(conjugate(z))
assert fresnels(z).diff(z) == sin(pi*z**2/2)
assert fresnels(z).rewrite(erf) == (1 + I)/4 * (
erf((1 + I)/2*sqrt(pi)*z) - I*erf((1 - I)/2*sqrt(pi)*z))
assert fresnels(z).rewrite(hyper) == \
pi*z**3/6 * hyper([Rational(3, 4)], [Rational(3, 2), Rational(7, 4)], -pi**2*z**4/16)
assert fresnels(z).series(z, n=15) == \
pi*z**3/6 - pi**3*z**7/336 + pi**5*z**11/42240 + O(z**15)
assert fresnels(y/z).limit(z, 0) == fresnels(oo*sign(y))
assert fresnels(x).taylor_term(-1, z) == 0
assert fresnels(x).taylor_term(1, z, *(pi*z**3/6,)) == -pi**3*z**7/336
assert fresnels(x).taylor_term(1, z) == -pi**3*z**7/336
assert fresnels(w).is_extended_real is True
assert fresnels(z).is_extended_real is None
assert fresnels(z).as_real_imag() == \
((fresnels(re(z) - I*re(z)*Abs(im(z))/Abs(re(z)))/2 +
fresnels(re(z) + I*re(z)*Abs(im(z))/Abs(re(z)))/2,
I*(fresnels(re(z) - I*re(z)*Abs(im(z))/Abs(re(z))) -
fresnels(re(z) + I*re(z)*Abs(im(z))/Abs(re(z)))) *
re(z)*Abs(im(z))/(2*im(z)*Abs(re(z)))))
assert fresnels(z).as_real_imag(deep=False) == fresnels(z).as_real_imag()
assert fresnels(w).as_real_imag() == (fresnels(w), 0)
assert fresnels(w).as_real_imag(deep=False) == fresnels(w).as_real_imag()
assert (fresnels(I, evaluate=False).as_real_imag() ==
(0, -erf(sqrt(pi)/2 + I*sqrt(pi)/2)/4 +
I*(-erf(sqrt(pi)/2 + I*sqrt(pi)/2) + erf(sqrt(pi)/2 -
I*sqrt(pi)/2))/4 - erf(sqrt(pi)/2 - I*sqrt(pi)/2)/4))
assert fresnels(2 + 3*I).as_real_imag() == (
fresnels(2 + 3*I)/2 + fresnels(2 - 3*I)/2,
I*(fresnels(2 - 3*I) - fresnels(2 + 3*I))/2
)
assert expand_func(integrate(fresnels(z), z)) == \
z*fresnels(z) + cos(pi*z**2/2)/pi
assert fresnels(z).rewrite(meijerg) == sqrt(2)*pi*z**Rational(9, 4) * \
meijerg(((), (1,)), ((Rational(3, 4),),
(Rational(1, 4), 0)), -pi**2*z**4/16)/(2*(-z)**Rational(3, 4)*(z**2)**Rational(3, 4))
assert fresnelc(0) == 0
assert fresnelc(+oo) == Rational(+1, 2)
assert fresnelc(-oo) == Rational(-1, 2)
assert fresnelc(z) == fresnelc(z)
assert fresnelc(-z) == -fresnelc(z)
assert fresnelc(I*z) == I*fresnelc(z)
assert fresnelc(-I*z) == -I*fresnelc(z)
assert conjugate(fresnelc(z)) == fresnelc(conjugate(z))
assert fresnelc(z).diff(z) == cos(pi*z**2/2)
pytest.raises(ArgumentIndexError, lambda: fresnels(z).fdiff(2))
pytest.raises(ArgumentIndexError, lambda: fresnelc(z).fdiff(2))
assert fresnelc(z).rewrite(erf) == (1 - I)/4 * (
erf((1 + I)/2*sqrt(pi)*z) + I*erf((1 - I)/2*sqrt(pi)*z))
assert fresnelc(z).rewrite(hyper) == \
z * hyper([Rational(1, 4)], [Rational(1, 2), Rational(5, 4)], -pi**2*z**4/16)
assert fresnelc(x).taylor_term(-1, z) == 0
assert fresnelc(x).taylor_term(1, z, *(z,)) == -pi**2*z**5/40
assert fresnelc(x).taylor_term(1, z) == -pi**2*z**5/40
assert fresnelc(z).series(z, n=15) == \
z - pi**2*z**5/40 + pi**4*z**9/3456 - pi**6*z**13/599040 + O(z**15)
assert fresnelc(y/z).limit(z, 0) == fresnelc(oo*sign(y))
# issue sympy/sympy#6510
assert fresnels(z).series(z, oo) == \
(-1/(pi**2*z**3) + O(z**(-6), (z, oo)))*sin(pi*z**2/2) + \
(3/(pi**3*z**5) - 1/(pi*z) + O(z**(-6), (z, oo)))*cos(pi*z**2/2) + Rational(1, 2)
assert fresnelc(z).series(z, oo) == \
(-1/(pi**2*z**3) + O(z**(-6), (z, oo)))*cos(pi*z**2/2) + \
(-3/(pi**3*z**5) + 1/(pi*z) + O(z**(-6), (z, oo)))*sin(pi*z**2/2) + Rational(1, 2)
assert fresnels(1/z).series(z) == \
(-z**3/pi**2 + O(z**6))*sin(pi/(2*z**2)) + (-z/pi + 3*z**5/pi**3 +
O(z**6))*cos(pi/(2*z**2)) + Rational(1, 2)
assert fresnelc(1/z).series(z) == \
(-z**3/pi**2 + O(z**6))*cos(pi/(2*z**2)) + (z/pi - 3*z**5/pi**3 +
O(z**6))*sin(pi/(2*z**2)) + Rational(1, 2)
assert fresnelc(w).is_extended_real is True
assert fresnelc(z).as_real_imag() == \
((fresnelc(re(z) - I*re(z)*Abs(im(z))/Abs(re(z)))/2 +
fresnelc(re(z) + I*re(z)*Abs(im(z))/Abs(re(z)))/2,
I*(fresnelc(re(z) - I*re(z)*Abs(im(z))/Abs(re(z))) -
fresnelc(re(z) + I*re(z)*Abs(im(z))/Abs(re(z)))) *
re(z)*Abs(im(z))/(2*im(z)*Abs(re(z)))))
assert fresnelc(2 + 3*I).as_real_imag() == (
fresnelc(2 - 3*I)/2 + fresnelc(2 + 3*I)/2,
I*(fresnelc(2 - 3*I) - fresnelc(2 + 3*I))/2
)
assert expand_func(integrate(fresnelc(z), z)) == \
z*fresnelc(z) - sin(pi*z**2/2)/pi
assert fresnelc(z).rewrite(meijerg) == sqrt(2)*pi*z**Rational(3, 4) * \
meijerg(((), (1,)), ((Rational(1, 4),),
(Rational(3, 4), 0)), -pi**2*z**4/16)/(2*root(-z, 4)*root(z**2, 4))
verify_numerically(re(fresnels(z)), fresnels(z).as_real_imag()[0], z)
verify_numerically(im(fresnels(z)), fresnels(z).as_real_imag()[1], z)
verify_numerically(fresnels(z), fresnels(z).rewrite(hyper), z)
verify_numerically(fresnels(z), fresnels(z).rewrite(meijerg), z)
verify_numerically(re(fresnelc(z)), fresnelc(z).as_real_imag()[0], z)
verify_numerically(im(fresnelc(z)), fresnelc(z).as_real_imag()[1], z)
verify_numerically(fresnelc(z), fresnelc(z).rewrite(hyper), z)
verify_numerically(fresnelc(z), fresnelc(z).rewrite(meijerg), z)
def test_sympyissue_5084():
x = Symbol('x')
assert ((x + x*I)/(1 + I)).as_real_imag() == (re((x + I*x)/(1 + I)),
im((x + I*x)/(1 + I)))
