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.
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