error_functions.py 文件源码

def _eval_aseries(self, n, args0, x, logx):
        point = args0[0]

        # Expansion at oo
        if point is S.Infinity:
            z = self.args[0]
            l = [ 1/sqrt(S.Pi) * C.factorial(2*k)*(-S(
                4))**(-k)/C.factorial(k) * (1/z)**(2*k + 1) for k in xrange(0, n) ]
            o = C.Order(1/z**(2*n + 1), x)
            # It is very inefficient to first add the order and then do the nseries
            return (Add(*l))._eval_nseries(x, n, logx) + o

        # Expansion at I*oo
        t = point.extract_multiplicatively(S.ImaginaryUnit)
        if t is S.Infinity:
            z = self.args[0]
            # TODO: is the series really correct?
            l = [ 1/sqrt(S.Pi) * C.factorial(2*k)*(-S(
                4))**(-k)/C.factorial(k) * (1/z)**(2*k + 1) for k in xrange(0, n) ]
            o = C.Order(1/z**(2*n + 1), x)
            # It is very inefficient to first add the order and then do the nseries
            return (Add(*l))._eval_nseries(x, n, logx) + o

        # All other points are not handled
        return super(_erfs, self)._eval_aseries(n, args0, x, logx)