czt

% error 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.