dft.m

matlab算法集 matlab算法集

function y = dft (x,dir)
%----------------------------------------------------------------
% Usage:       y = dft (x,dir)
%
% Description: Compute the one-dimensional discrete Fourier 
%              transform (DFT) or its inverse. When the number
%              of points is a power of 2, use the efficient
%              fast Fourier transform (FFT) technique.
%
% Inputs:      x   = n by 1 complex vector containing samples
%                    to be transformed.
%              dir = direction code.  If dir >= 0, compute
%                    the forward DFT of x, otherwise compute 
%                    the inverse DFT of x.
%
% Outputs:     y = n by 1 vector containing transformed samples.
%
% Note:        For definitions of DFT and inverse DFT, type
%              help fft.
%----------------------------------------------------------------

   chkvec (x,1,'dft');
   if dir >= 0
      y = fft (x);
   else
      y = ifft (x);
   end 
%----------------------------------------------------------------