'Fourier transform of AR polynomial, zero-padded at end to n
Parameters
n : int
length of array after zero-padding
Returns
fftar : ndarray
fft of zero-padded ar polynomial'

def fftar(self, n=None):

    if (n is None):
        n = len(self.ar)
    return fft.fft(self.padarr(self.ar, n))
