www.gusucode.com > datafun 工具箱matlab源码程序 > datafun/fft.m
%FFT Discrete Fourier transform. % FFT(X) is the discrete Fourier transform (DFT) of vector X. For % matrices, the FFT operation is applied to each column. For N-D % arrays, the FFT operation operates on the first non-singleton % dimension. % % FFT(X,N) is the N-point FFT, padded with zeros if X has less % than N points and truncated if it has more. % % FFT(X,[],DIM) or FFT(X,N,DIM) applies the FFT operation across the % dimension DIM. % % For length N input vector x, the DFT is a length N vector X, % with elements % N % X(k) = sum x(n)*exp(-j*2*pi*(k-1)*(n-1)/N), 1 <= k <= N. % n=1 % The inverse DFT (computed by IFFT) is given by % N % x(n) = (1/N) sum X(k)*exp( j*2*pi*(k-1)*(n-1)/N), 1 <= n <= N. % k=1 % % See also FFT2, FFTN, FFTSHIFT, FFTW, IFFT, IFFT2, IFFTN. % Copyright 1984-2005 The MathWorks, Inc. % Built-in function.