usage y=czt(x, m, w, a)

Chirp z-transform.  Compute the frequency response starting at a and
stepping by w for m steps.  a is a point in the complex plane, and
w is the ratio between points in each step (i.e., radius increases
exponentially, and angle increases linearly).

To evaluate the frequency response for the range f1 to f2 in a signal
with sampling frequency Fs, use the following:
m = 32;                               ## number of points desired
w = exp(-j*2*pi*(f2-f1)/((m-1)*Fs));  ## freq. step of f2-f1/m
a = exp(j*2*pi*f1/Fs);                ## starting at frequency f1
y = czt(x, m, w, a);

If you don't specify them, then the parameters default to a fourier
transform:
m=length(x), w=exp(-j*2*pi/m), a=1

If x is a matrix, the transform will be performed column-by-column.