Non-uniform FFT with Matlab

Hi everyone,

I need to perform a non-uniform fft in 3D (to solve the heat equation using the method described here).

More precisely, I am using a uniform grid in space and a non uniform grid in the frequency domain. After several topics in this forum, I tried to use the toolbox NFFT3 which seemed great. I was able to use it on a non equispaced spatial grid but the Matlab function does not seem to allow for specifying the frequency grid points...

Does anyone have experience on NUFFT with Matlab and, if yes, how do you perform your computations ?

I have read that this function was included into FFTW (used by Matlab) : is the function included in some Mathworks product ?

Best regards,

Anthony

PS : I am also trying to use this toolbox but it somehow lacks documentation...

Answer 1

[Matt J]

PS : I am also trying to use this toolbox but it somehow lacks documentation...

The relevant functions nufft.m and nufft_init.m in that toolbox do have help text in them. If the help text is unclear, perhaps you can email the author for clarification.

[Matt J]

There is also a Journal Article referenced by the toolbox. Maybe that can help clarify its use.

Answer 2

[Anthony]

Hi Matt,

Thanks to the paper, I finally managed to make it work (after a change of variable). The key is to carefully read the formulas 2 and 37.5 (between 37 and 38, it has no number in the paper) in order to understand their convention.

Anthony