KISS FFT - A mixed-radix Fast Fourier Transform based up on the principle
"Keep It Simple, Stupid."

There are many great fft libraries already around. Kiss FFT is not trying to
be better than any of them. It only attempts to be a reasonably efficient,
moderately useful FFT that can use fixed or floating data types and can be
incorporated into someone's C program in a few minutes with trivial licensing.
