Conversely, when one wants to compute an arbitrary number () of discrete samples of one cycle of a continuous DTFT, , it can be done by computing the relatively simple DFT of , as defined above. In most cases, is chosen equal to the length of non-zero portion of . Increasing , known as "zero-padding" or "interpolation", results in more closely spaced samples of one cycle of . Decreasing , causes overlap (adding) in the time-domain (analogous to aliasing), which corresponds to decimation in the frequency domain. (see ) In most cases of practical interest, the sequence represents a longer sequence that was truncated by the application of a finite-length window function or FIR filter array.