transforms.py 文件源码

def _sine_cosine_transform(f, x, k, a, b, K, name, simplify=True):
    """
    Compute a general sine or cosine-type transform
        F(k) = a int_0^oo b*sin(x*k) f(x) dx.
        F(k) = a int_0^oo b*cos(x*k) f(x) dx.

    For suitable choice of a and b, this reduces to the standard sine/cosine
    and inverse sine/cosine transforms.
    """
    F = integrate(a*f*K(b*x*k), (x, 0, oo))

    if not F.has(Integral):
        return _simplify(F, simplify), True

    if not F.is_Piecewise:
        raise IntegralTransformError(name, f, 'could not compute integral')

    F, cond = F.args[0]
    if F.has(Integral):
        raise IntegralTransformError(name, f, 'integral in unexpected form')

    return _simplify(F, simplify), cond