Help with using IFFT to calculate radial distribution function g(r) , matlab

[albaraa]

Hi all, I am trying to use ifft function to evaluate the radial distribution function g(r), r is distance (nm), by using the structure factor s(q) , which is function of wave vector q (1/nm) :



I did this by using normal integration (quad) but it takes long time to calculate it. So I believe I can use ifft to do this since the function s(q) is a discrete function.

I do not know what input I have to use in ifft() ? do I have to put q*s(q) ? what about sin (q r) ? Is it just : image (ifft()) ? Do I have to take in my account Nyquist frequency in my data ?

I am sorry there are too many questions but I am REALLY confused ):

Any help will be appreciated!

Thanks a lot .