error_functions.py 文件源码

def eval(cls, nu, z):
        from sympy import (unpolarify, expand_mul, uppergamma, exp, gamma,
                           factorial)
        nu2 = unpolarify(nu)
        if nu != nu2:
            return expint(nu2, z)
        if nu.is_Integer and nu <= 0 or (not nu.is_Integer and (2*nu).is_Integer):
            return unpolarify(expand_mul(z**(nu - 1)*uppergamma(1 - nu, z)))

        # Extract branching information. This can be deduced from what is
        # explained in lowergamma.eval().
        z, n = z.extract_branch_factor()
        if n == 0:
            return
        if nu.is_integer:
            if (nu > 0) != True:
                return
            return expint(nu, z) \
                - 2*pi*I*n*(-1)**(nu - 1)/factorial(nu - 1)*unpolarify(z)**(nu - 1)
        else:
            return (exp(2*I*pi*nu*n) - 1)*z**(nu - 1)*gamma(1 - nu) + expint(nu, z)