idft.m

来自「用matlab编写的数字信号处理程序」· M 代码 · 共 26 行

function[xn]=idft(Xk,N)
%Computes Inverse Discrete Transform
%-----------------------------------
%[xn]=idft(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 N matrix of nk values
WNnk=WN.^(-nk);        %IDFT matrix  
xn=(Xk*WNnk)/N         %row vector for IDFT values