Hi Issac,
You can implement the DTFT using the following code snippet,
function [X] = dtft(x,n,w)
% Computes Discrete-time Fourier Transform
% [X] = dtft(x,n,w)
% X = DTFT values computed at w frequencies
% x = finite duration sequence over n
% n = sample position vector
% w = frequency location vector
X = exp(-1i*w'*n) * x.';
% X = x*exp(-j*n'*w);
end
Hope this Helps!
