test_transforms.py 文件源码

def test_as_integral():
    from sympy import Function, Integral
    f = Function('f')
    assert mellin_transform(f(x), x, s).rewrite('Integral') == \
        Integral(x**(s - 1)*f(x), (x, 0, oo))
    assert fourier_transform(f(x), x, s).rewrite('Integral') == \
        Integral(f(x)*exp(-2*I*pi*s*x), (x, -oo, oo))
    assert laplace_transform(f(x), x, s).rewrite('Integral') == \
        Integral(f(x)*exp(-s*x), (x, 0, oo))
    assert str(inverse_mellin_transform(f(s), s, x, (a, b)).rewrite('Integral')) \
        == "Integral(x**(-s)*f(s), (s, _c - oo*I, _c + oo*I))"
    assert str(inverse_laplace_transform(f(s), s, x).rewrite('Integral')) == \
        "Integral(f(s)*exp(s*x), (s, _c - oo*I, _c + oo*I))"
    assert inverse_fourier_transform(f(s), s, x).rewrite('Integral') == \
        Integral(f(s)*exp(2*I*pi*s*x), (s, -oo, oo))

# NOTE this is stuck in risch because meijerint cannot handle it