Related Transforms

There are alternatives to the Cooley-Tukey FFT which can serve the same or related purposes and which can have advantages in certain situations [8]. Examples include the fast discrete cosine transform (DCT) [4], discrete Hartley transform [19], number theoretic transform [2], prime factor algorithm (PFA) [34,42,8,81],^A.10and the Winograd Fourier transform [42]. A tutorial review of fast Fourier transform algorithms (1990) is given in [20].^A.11

The DCT, used extensively in image coding, is described in §A.6.1 below. The Hartley transform, optimized for processing real signals, does not appear to have any advantages over a ``pruned real-only FFT'' [72]. The number theoretic transform has special applicability for large-scale, high-precision calculations (see §A.6.2 below). The PFA and Winograd transform are closely related, with the PFA being somewhat faster [7].