FFTW is a C subroutine library for computing the discrete Fourier transform (DFT) in one or more dimensions, of arbitrary input size, and of both real and complex data (as well as of even/odd data, i.e. the discrete cosine/sine transforms or DCT/DST).
Benchmarks performed on a variety of platforms show that FFTW's performance is typically superior to that of other publicly available FFT software, and is even competitive with vendor-tuned codes. In contrast to vendor-tuned codes, however, FFTW's performance is portable: the same program will perform well on most architectures without modification.
The FFTW library is required by other codes such as StarCrash (ascl:1010.074) and Hammurabi (ascl:1201.014).
M. Frigo and S. G. Johnson, "The Design and Implementation of FFTW3," in Proceedings of the IEEE, vol. 93, no. 2, pp. 216-231, Feb. 2005, doi: 10.1109/JPROC.2004.840301. See additional information here: https://www.fftw.org/fftw.bib