for x[n]=n-64, for n: 0 to 127

find its DFT...which can be done using inbuild function fft.... but after finding its dft, say Y[k]=DFT{x[n]},...i want to make high frequency samples zeros i.e for any values of L=20,40,60....i want Y[64-L]=Y[64]=Y[64+L]=0,...i am not geting how to make these samples zeros in the dft y[k].

[Adam]

If you have the dft then surely it is trivial. Just index into it and set the relevant values to 0.