An exact method to sample the DTFT of an N +1-length sequence at intervals of 1 / N is described at DTFT § L=N+1. Essentially, w [ N ] is combined with w [ 0 ] (by addition), and an N -point DFT is done on the truncated sequence. Similarly, spectral analysis would be done by combining the n = 0 and n = N data samples before applying the truncated symmetric window. That is not a common practice, even though truncated windows are very popular.