FFTW is a C subroutine library for computing the Discrete Fourier
Transform (DFT) in one or more dimensions, of both real and complex
data, and of arbitrary input size. We believe that FFTW, which is free
software, should become the FFT library of choice for most
applications. Our benchmarks, performed on on a variety of platforms,
show that FFTW's performance is typically superior to that of other
publicly available FFT software.