The Fast Fourier Transform (FFT) is an algorithm for computing the Discrete Fourier Transform (DFT) of a sequence of N complex numbers in O(N log N) time, instead of the O(N^2) time required by the naive DFT algorithm. The DFT is a mathematical technique used to analyze signals in the frequency domain. It converts a signal in the time domain, such as a function of time, into a function of freque..