def freqz(b, a=1, worN=None, whole=False, plot=None):
    b, a = map(atleast_1d, (b, a))
    if whole:
        lastpoint = 2 * pi
    else:
        lastpoint = pi
    if worN is None:
        N = 512
        w = numpy.linspace(0, lastpoint, N, endpoint=False)
    elif isinstance(worN, int):
        N = worN
        w = numpy.linspace(0, lastpoint, N, endpoint=False)
    else:
        w = worN
    w = atleast_1d(w)
    zm1 = exp(-1j * w)
    h = polyval(b[::-1], zm1) / polyval(a[::-1], zm1)
    if plot is not None:
        plot(w, h)

    return w, h
Compute the frequency response of a digital filter.
dataset/ETHPy150Open scipy/scipy/scipy/signal/filter_design.py/freqz