Practical implementations of the DFT are usually based on one of the
Cooley-Tukey ``Fast Fourier Transform'' (FFT) algorithms
[14].^{8.1} For this reason, the matlab
DFT function is called '`fft`', and the actual algorithm used
depends primarily on the transform length .^{8.2} The fastest FFT algorithms generally occur when
is a power of 2. In practical audio signal processing, we
routinely zero-pad our FFT input buffers to the next power of 2 in
length (thereby interpolating our spectra somewhat) in order to enjoy
the power-of-2 speed advantage. Finer spectral sampling is a
typically welcome side benefit of increasing to the next power of
2. A short introduction/overview of some of the better known FFT
algorithms, and some pointers to literature and online resources, are
given in Appendix A.

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