*''N'' is customarily chosen to be an integer power-of-2, which optimizes the efficiency of the [[Fast Fourier transform|FFT]] algorithm.
*Optimal N is in the range [4M, 8M].
*Unlike the third[[Overlap-add graphmethod]], in the figure above,which depictingpreserves separate leading and trailing edge-effects, this method causes them to be overlapped and added. So they are discarded together. In other words, with circular convolution, the first output value is a weighted average of the <u>last</u> M-1 samples of the input segment (and the first sample of the segment). The next M-2 outputs are weighted averages of both the beginning and the end of the segment. The M<sup>th</sup> output value is the first one that combines only samples from the beginning of the segment.
