What have you already tried?
As I have no idea where to start, I haven't tried anything, I'm currently searching for an "easy" way to use FFTW, by easy I mean under 300-500 lines properly written/formatted/understandable code, after that I'm planning to actually try to compile FFTW, as it's primary platform seems to be GCC and Linux, it's not that straight-forward to compile it on Windows.
(Everyone should start using CMake IMO)
FFTW is the most popular library for FFT. What's the problem with C? I think it's ok for low-level libraries that provide very precise functionality. It's not as if we were talking about a full game framework
The problem with C is, it's not C++ (which I'm used to, and am probably too lazy to drop my habits).
What don't you understand exactly? We're not going to write the full code for you
That's obvious, so I wasn't expecting it.
As for what I don't understand, I haven't tried much, yet, but I'm going to give FFTW a try now, if I encounter any trouble on my way of using the both libraries together, or actually succeed in it, I'm going to report back with code and a detailed explanation on the problem/solution.
In the mean time, if anyone has some code from their previous/current project, feel free to donate, if you feel like it.
Whoops, I failed to notice that FFTW was GPL, so it's out of the question, FFTReal remains, and is under the WTFPL, and I think it will suffice, once I figure out how to use it.
Update: FFTReal is used in the
Qt spectrum demo, time to try and adapt it to SFML.