[SOLVED] FFT & IFFT with different lengths

[emicho]

Signal is a 160 samples
and I am obligated to apply a 512 FFT
is there any way that I could restore my signal
with a 160 IFFT

X=FFT(signal,512)
x=IFFT(X,160)

x == signal !?!?

how can I make this relation possible
any Idea guys?!
please help

 

[zorro]

When you perform FFT of 512 points, the signal must have exactly 512 values, If it has less, it must be zero-padded. Apparently the FFT function you are using does this automatically (Matlab does).
Then, if you perform IFFF of that, you get the data on which FFT was applied (i.e. zero-padded signal), whose 160 first samples are the original signal.
Regards

Z