FXT is a C++ library containing code for various fast orthogonal
transforms (Fourier-, Hartley-, Walsh-, Haar-, Wavelet-transform) and
convolution. It contains a large collection of low (bit) level routines
and combinatorial algorithms (permutations, combinations, necklaces, de
Bruijn sequences). Number theoretic transforms and modular arithmetics
are implemented. Operations on binary polynomials and arithmetics in
finite fields GF(2^n) are included. The package contains more than 150
short programs that demonstrate how to use its functionality.