What is the difference between ifft(f) and ifft(f,n)?
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Hi. I have one vector f with some values of velocity in function of the frequency. I have to plot this velocities in function of the time. I don't know if I have to use ifft(f) or ifft(f,n). In this last case, what is n?
Thanks.
1 个评论
Daniel Shub
2013-1-28
I am not a huge fan of RTFM answers, but in this case ... what does help ifft or doc ifft say about what n is?
回答（1 个）
John Petersen
2013-1-29
编辑：John Petersen
2013-1-29
0 个投票
if N =length(f), there is no difference between ifft(f) and ifft(f,N)
2 个评论
Marcia Azeredo
2013-1-29
John Petersen
2013-2-4
You can zero pad f so that it has the N samples. e.g. Say f is a 256 element column array and N = 400.
f1 = [f; zeros(400-256,1)];
iF = ifft(f);
iF1 = ifft(f1,N);
figure;plot(iF1);
hold on; plot(iF,'r')
Now you can see the difference, just zero padded at the end. Is this what you wanted?
Does the time vector correspond to the sampling points of the signal f?
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2013-1-28
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