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function [y, xm]= rceps(x)
//Produce the cepstrum of the signal x, and if desired, the minimum phase reconstruction of the signal x.
//Calling Sequence
//[y, xm] = rceps(x)
//Parameters
//x: real or complex vector input
//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.
//Examples
// 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
if(argn(2)~= 1 )
error("Wrong number of Input Arguments");
end
if(argn(1)>2)
error("Wrong number of Output Arguments")
end
f = abs(fft1(x));
if (or(f == 0))
error ("The spectrum of x contains zeros, unable to compute real cepstrum");
end
y = real(ifft1(log(f)));
if argn(1) == 2 then
n=length(x);
if size(x,1)==1 then
if (n-fix(n./2).*2) ==1 then
xm = [y(1), 2*y(2:n/2+1), zeros(1,n/2)];
else
xm = [y(1), 2*y(2:n/2), y(n/2+1), zeros(1,n/2-1)];
end
else
if (n-fix(n./2).*2)==1
xm = [y(1,:); 2*y(2:n/2+1,:); zeros(n/2,size(y,2))];
else
xm = [y(1,:); 2*y(2:n/2,:); y(n/2+1,:); zeros(n/2-1,size(y,2))];
end
end
xm = real(ifft1(exp(fft1(xm)')));
end
endfunction
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