%FFT Discrete Fourier transform.
%   FFT(X) is the discrete Fourier transform (DFT) of vector X.  If the
%   length of X is a power of two, a fast radix-2 fast-Fourier
%   transform algorithm is used.  If the length of X is not a
%   power of two, a slower non-power-of-two algorithm is employed.
%   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
%
%   The relationship between the DFT and the Fourier coefficients a and b in
%               N/2
%   x(n) = a0 + sum a(k)*cos(2*pi*k*t(n)/(N*dt))+b(k)*sin(2*pi*k*t(n)/(N*dt))
%               k=1
%   is
%      a0 = X(1)/N, a(k) = 2*real(X(k+1))/N, b(k) = -2*imag(X(k+1))/N,
%   where x is a length N discrete signal sampled at times t with spacing dt.
%
%   See also IFFT, FFT2, IFFT2, FFTSHIFT.

%   Copyright (c) 1984-98 by The MathWorks, Inc.
%   $Revision: 5.9 $  $Date: 1998/06/30 18:43:41 $

%   Built-in function.


