General Purpose FFT (Fast Fourier/Cosine/Sine Transform) Package
/* * http://www.kurims.kyoto-u.ac.jp/~ooura/fft.html * Copyright Takuya OOURA, 1996-2001 * * You may use, copy, modify and distribute this code for any purpose (include * commercial use) and without fee. Please refer to this package when you modify * this code. * /