WALSH is a FORTRAN90 library which implements versions of the Walsh and Haar transforms.
Note that the programs, as printed in the reference, had a few typographical errors. Several programs, in particular FHT and FRT, could not be made to perform as described in the text, and hence have been omitted.
The computer code and data files described and made available on this web page are distributed under the GNU LGPL license.
WALSH is available in a C version and a C++ version and a FORTRAN77 version and a FORTRAN90 version and a MATLAB version.
FFTPACK5, a FORTRAN90 library which implements the Fast Fourier Transform by Paul Swarztrauber and Dick Valent;
HAAR, a FORTRAN90 library which computes the Haar transform of data.
SFTPACK, a FORTRAN90 library which implements the "slow" Fourier transform, intended as a teaching tool and comparison with the fast Fourier transform.
SINE_TRANSFORM, a FORTRAN90 library which demonstrates some simple properties of the discrete sine transform.
WAVELET, a FORTRAN90 library which does some simple wavelet calculations;
You can go up one level to the FORTRAN90 source codes.