fxt is a library package (coming as C++ source code) containing various algorithms for: - Fast Fourier Transform (FFT) incl. real-valued, - multidimensional and weighted variants. - Fast Hartley Transform (FHT) - Number Theoretic Transform (NTT), Fast Walsh Transform. - Convolution (cyclic, linear and weighted), - correlation and power spectrum. - Fast Haar Transform, Fast Wavelet Transform - Mass storage convolution and fast multiplication routines. - Sine- and cosine transform (DCT, DST), Fast Z-Transform (FZT)