usage: [y, xm] = rceps(x)
Produce the cepstrum of the signal x, and if desired, the minimum
phase reconstruction of the signal x.  If x is a matrix, do so
for each column of the matrix.

Example
f0=70; Fs=10000;           # 100 Hz fundamental, 10kHz sampling rate
a=poly(0.985*exp(1i*pi*[0.1, -0.1, 0.3, -0.3])); # two formants
s=0.005*randn(1024,1);      # Noise excitation signal
s(1:Fs/f0:length(s)) = 1;   # Impulse glottal wave
x=filter(1,a,s);            # Speech signal in x
[y, xm] = rceps(x.*hanning(1024)); # cepstrum and min phase reconstruction

Reference
Programs for digital signal processing. IEEE Press.
New York: John Wiley & Sons. 1979.