Some FFT Codelets based on the book by Charles Van Loan
These C++ codelets aren't particularly useful as a practical FFT impementation but you can use them as a reference point in understanding the basics of FFT implementation. Most codelets are based on the Van Loan book. If you are looking for a practical implementation then you can't go wrong with FFTW. If you are looking for a reasonably fast and highly portable code then check out my webpage on google code - http://code.google.com/p/hsfft/
Usage - See the example file. The documentation is non-existent but the usage is pretty straightforward. FFT Alogithms are in the fft_var.h file. Just make sure that the file and directory structure is maintained. You can use tools/cycle.h to time performances of various implementations.