How to replace numbers in a column vector after certain elements?

How should we proceed if we have a column vector X with 1000 elements, and we wish to replace all the values after a certain row, say after 600, by zeros? The context is basically filtering in the Fourier domain. It may not be the efficient way, but I just wish to see what happens to the inverse transform? Thanks.

Answer 1

[madhan ravi]

X(600+1 : end) = 0;