FFT is not accurate?
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I have a question about FFT. I thought the FFT should converge to the continious fourier transform for a large number of samples. Is that true? Performing an FFT of a rectangular pulse with Matlab leads to a function that resembles a sinc function but is not identical to it, no matter how many samples I use.
Here is how I have implemented it:
k=[0:2048,-2047:-1];
r=[ones(1,64),zeros(1,3969),ones(1,63)];
sitrafo=real(fft(r,4096,2));
sireal=127*sinc(k*127/4096);
figure(1);
plot(k,sitrafo);grid;
hold on;
plot(k,sireal,'g');
Any hints are very much appreciated!
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Answers (1)
Azzi Abdelmalek
on 28 Jul 2012
i have posted a function get_harmoniques on file exchange, it will appear, maby tomorow, or after the week-end. try it and tell me about it.
1 Comment
Azzi Abdelmalek
on 30 Jul 2012
Edited: Azzi Abdelmalek
on 30 Jul 2012
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