idft.m

信号进行FFT变换,可以选择多个洋点,

function xn=idft(Xk)
N=length(Xk);
Xk1=Xk(1:N);
n=0:N-1;
k=0:N-1;
WN=exp(-j*2*pi/N);
nk=n'*k;
WNnk=WN.^(-nk);
xn=Xk1*WNnk/N;