dtft.m

matlab例子

function [X]=dtft(x,n,w)
% Calculate discret time Fourier transform
% [X]=dtft(x,n,w)
% X=DTFT array at frequency w
% x=infinite series (length=n)
% n=position vector of sample
% w=position vector of frequency
if w(1)==0
   k=w*(length(w)-1)/pi;
   X=x*(exp(-j*pi/(length(w)-1))).^(n'*k);
else
   k=w*(length(w)-1)/(2*pi);
   X=x*(exp(-j*2*pi/(length(w)-1))).^(n'*k);
end