与MATLAB逆FFT不起作用

Question

I am trying to do an inverse FFT in Matlab, but I can't seem to get the inverse working correctly. Here is my code:

    data = [-0.0005
       -0.0004
       -0.0003
       -0.0002
       -0.0001
       -0.0000
        0.0001
        0.0001
        0.0001
        0.0002
        0.0002
        0.0002
        0.0002
        0.0002
        0.0002
        0.0002
        0.0002
        0.0002
        0.0003
        0.0004
        0.0005
        0.0006
        0.0007
        0.0009
        0.0010
        0.0011
        0.0011
        0.0012
        0.0011
        0.0011
        0.0011
        0.0010 ];    


%plot data
figure(1)
plot(data)    

%FFT
N = 100;
X = fft(data, N);
F = [-N/2:N/2-1]/N;
F = F/0.0125;

X = fftshift(X);
figure(2)
plot(F, abs( X ) )

%inverse FFT
y = ifft(X);
figure(3)
plot(F,y)

Figure 1 and 3 should be identical, but are not in any way. I made sure not to take ifft of the absolute value of fft , so it's not clear to me what is wrong.

Answer 1

由于使用fftshift移位了频谱，因此在进行傅立叶逆变换之前，必须先“消除”频谱

y = ifft(fftshift(X));