sftpack_test, a C code which calls sftpack() to carry out some "slow" Fourier transforms, that is, Fourier transforms without the techniques that allow for very fast computation.
The computer code and data files described and made available on this web page are distributed under the MIT license
sftpack, a C code which implements the slow Fourier transform, intended as a teaching tool and comparison with the Fast Fourier Transform (FFT).