Fast Fourier Transform (FFT) < Mathematics Software in the Yahoo! Directory

FFTW
Free C FFT library including multi-dimensional, real, and parallel transforms.
www.fftw.org
Web Directory: FFT Links
Descriptions of many FFT-related sites on the Web, with links.
www.fftw.org/links.html
General Purpose FFT Package
C/Fortran code for the Discrete Fourier/Cosine/Sine Transform.
momonga.t.u-tokyo.ac.jp/~ooura/fft.html
FFTPACK
Package of Fortran subprograms for the fast Fourier transform of periodic and other symmetric sequences.
www.netlib.org/fftpack/index.html
Performance and Accuracy Benchmark of FFT and FHT Algorithms
www.geocities.com/ResearchTriangle/8869/fft_summary.html

Mathematics Software > Fast Fourier Transform (FFT)