'Test firwin2 for calculating Type IV filters'

def test05(self):

    ntaps = 1500
    freq = [0.0, 1.0]
    gain = [0.0, 1.0]
    taps = firwin2(ntaps, freq, gain, window=None, antisymmetric=True)
    assert_array_almost_equal(taps[:(ntaps // 2)], (- taps[(ntaps // 2):][::(-1)]))
    (freqs, response) = freqz(taps, worN=2048)
    assert_array_almost_equal(abs(response), (freqs / np.pi), decimal=4)
