idft.m

很多matlab的源代码

function [xn] = idft(Xk,N)
%N=4;
%Xk = [0 ,1 ,2, 3];

% Computes Inverse Discrete Transform
% -------------------------------------------------
% [xn] = idfs(Xk,N)
% xn =N-point sequence over 0 <= n <= N-1
% Xk = DFT coeff.array over 0 <= k <= N-1
% N = Length of DFT
%
n = [0:1:N-1];              % row vector for n
k = [0:1:N-1];              % row vector for k
WN = exp(-j*2*pi/N);        % Wn factor
nk = n'*k;                  % creates a N by matrix of nk values
WNnk = WN.^nk;              % IDFT matrix
xn = (Xk * WNnk)/N;         % row vector for IDFT Values