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Subject: FFT,IFFT, and NDFT,NFFT
Date: Sat, 27 Jun 2009 20:25:02 +0000 (UTC)
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1. When we have irregular sampling, we can use NDFT on it instead of FFT 
NDFT equation
f_j = \sum_{k=-N/2}^{N/2-1} \hat f_k e^{(-2 *pi*i*k*x_j)}

k= (-N/2:N/2-1)
x_j=time domain (j=0,1,2____M-1)

So what my question is, whenever we have non uniform sampling in the one domain will we get uniform sampling in another domain. For ex if my time domain is irregular, will i be getting regular sampling in frequency domain


2. Inverting NDFT is not a easy task as in FFT, In ifft A inverse is equal to A conjugate, because of uniform sampling or fixed sampling in time domain that why IFFT is easy to apply. Please correct me if am wrong.

If any one interested in non uniform sampling, here is one good article
http://www.mathematik.tu-chemnitz.de/preprint/quellen/2006/PREPRINT_01.pdf
I didnt understand quiet few things in it, if any one wana discuss..:) will be happy