The General Fourier Family Transform (GFT) is a time-frequency transform. The Fourier, short-time Fourier and S- transforms are special cases. This is an efficient n log n algorithm for computing the GFT which is most interesting to use to compute the S-transform (ST). The ST is like a short time Fourier transform in that it produces a frequency vs. time (or space) spectrogram, but it is frequency adaptive like a wavelet.
