NON UNIFORM FAST FOURIER TRANSFORM
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From: kk KKsingh on 19 May 2010 20:20 JUST Wondering whether any one is working on Non uniform fast Fourier transform
From: TideMan on 19 May 2010 21:16 On May 20, 12:20 pm, "kk KKsingh" <akikumar1...(a)gmail.com> wrote: > JUST Wondering whether any one is working on Non uniform fast Fourier transform Oh, you're back.................. Did you take any of the advice you were offered on this subject back in April? Several people suggested several courses of action you. Have you pursued any of these at all? If so, why not show us where you've got to? If not, why not?
From: kk KKsingh on 20 May 2010 17:02 TideMan <mulgor(a)gmail.com> wrote in message <7535a242-c1b7-4191-9cc6-2380d81d113c(a)t34g2000prd.googlegroups.com>... > On May 20, 12:20 pm, "kk KKsingh" <akikumar1...(a)gmail.com> wrote: > > JUST Wondering whether any one is working on Non uniform fast Fourier transform > > Oh, you're back.................. > Did you take any of the advice you were offered on this subject back > in April? > Several people suggested several courses of action you. > Have you pursued any of these at all? > If so, why not show us where you've got to? > If not, why not? I was able to get the same result as DFT from my code ! But now i need to go back inverse i am going some thing wrong ....MY NFFT and DFT is same so no issues with it ...But inverse is not easy for me Aki
From: kk KKsingh on 20 May 2010 17:56 "kk KKsingh" <akikumar1983(a)gmail.com> wrote in message <ht480c$pr9$1(a)fred.mathworks.com>... > TideMan <mulgor(a)gmail.com> wrote in message <7535a242-c1b7-4191-9cc6-2380d81d113c(a)t34g2000prd.googlegroups.com>... > > On May 20, 12:20 pm, "kk KKsingh" <akikumar1...(a)gmail.com> wrote: > > > JUST Wondering whether any one is working on Non uniform fast Fourier transform > > > > Oh, you're back.................. > > Did you take any of the advice you were offered on this subject back > > in April? > > Several people suggested several courses of action you. > > Have you pursued any of these at all? > > If so, why not show us where you've got to? > > If not, why not? > > I was able to get the same result as DFT from my code ! But now i need to go back inverse i am going some thing wrong ....MY NFFT and DFT is same so no issues with it ...But inverse is not easy for me > > Aki This is the library which i am trying to work with ! Just wondering any one tried this http://www-user.tu-chemnitz.de/~potts/nfft/
From: Greg Heath on 20 May 2010 21:27
On May 20, 5:02 pm, "kk KKsingh" <akikumar1...(a)gmail.com> wrote: > TideMan <mul...(a)gmail.com> wrote in message <7535a242-c1b7-4191-9cc6-2380d81d1...(a)t34g2000prd.googlegroups.com>... > > On May 20, 12:20 pm, "kk KKsingh" <akikumar1...(a)gmail.com> wrote: > > > JUST Wondering whether any one is working on Non uniform fast Fourier transform > > > Oh, you're back.................. > > Did you take any of the advice you were offered on this subject back > > in April? > > Several people suggested several courses of action you. > > Have you pursued any of these at all? > > If so, why not show us where you've got to? > > If not, why not? > > I was able to get the same result as DFT from my code ! But now i need to go back inverse i am going some thing wrong ....MY NFFT and DFT is same so no issues with it ...But inverse is not easy for me I have responded to so many of your posts I have lost track. The answer to this question is in one of my previous replies. The bottom line is: If you assume the nonuniformly sampled time function can be recovered from the traditional IDFT numerical integration formula, the spectrum should be obtained from the time function using least squares, not the DFT numerical integration formula. However, if the time and frequency sampling are both uniform and use the same number of points, the DFT is the least-square solution. Hope this helps. Greg |