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Fourier and FFT: Powers of 2 only?


Hi everybody.
I have a question that can be brutely summarized in: "What's in
Fourier[] guts?"
Well, for sure it's an FFT algorithm. I've found out something about
among the technical questions on the web site, but what I'd like to
know is:

Since FFT procs work best with sets of points whose number is a power of
2, what does Fourier[] do when it's fed a set of, say, 200 points? Will
it extend to 256 by adding zeros, or split it in subsets that are power
of 2, or whatever?

One more question:
I've read something about "Mixed Radix FFT": some sort of FFT that can
be extended to powers of any prime instead of powers of 2 only. I know
nothing more about it, but I was wondering if there is some easy (not
necessarily efficient) way to implement it in Mathematica. Just for
toying with.

Best Regards,
Peltio,
peltioNOSPAM at usa.net








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