signal.py 文件源码

def correlate_periodic(a, v=None):
    """Cross-correlation of two 1-dimensional periodic sequences.

    a and v must be sequences with the same length. If v is not specified, it is
    assumed to be the same as a (i.e. the function computes auto-correlation).

    :param a: input sequence #1
    :param v: input sequence #2
    :returns: discrete periodic cross-correlation of a and v
    """
    a_fft = _np.fft.fft(_np.asarray(a))
    if v is None:
        v_cfft = a_fft.conj()
    else:
        v_cfft = _np.fft.fft(_np.asarray(v)).conj()
    x = _np.fft.ifft(a_fft * v_cfft)
    if _np.isrealobj(a) and (v is None or _np.isrealobj(v)):
        x = x.real
    return x