Fast convolution is using the FFT, multiplication in the frequency domain, and inverse FFT to perform convolution of a long signal with a long FIR.

Fast convolution is using the Fast Fourier Transform (FFT), multiplication in the frequency domain, and inverse FFT to perform the convolution of a long signal with a long FIR. The "Overlap-Add" (OLA) and "Overlap-Save"(OLS) techniques are the two currently known basic methods.

The FFT is an efficient (or "fast") method to compute the Discrete Fourier Transform (DFT). Using the DFT performs circular convolution because of the inherent periodic nature of the DFT and OLA or OLS are techniques to use the circular convolution tool to accomplish the task of linear convolution.

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