Fourier and FFT: Powers of 2 only?

*To*: mathgroup at smc.vnet.net*Subject*: [mg15839] Fourier and FFT: Powers of 2 only?*From*: "Peltio" <pelt.ioNOS at PAMiol.it>*Date*: Fri, 12 Feb 1999 18:39:59 -0500 (EST)*Organization*: Peltio Inc.*Sender*: owner-wri-mathgroup at wolfram.com

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