Backup diff of Filter/Window vs current(No. 1)

• https://www.logical-arts.jp/archives/124

今更だけど、Hamming Window の0.54ってどこから来てるのかと思ったら，25/46の近似値だったのか． F. J. Harris, "On the Use of Windows for Harmonic Analysis with the Discrete Fourier Transform," Proc. IEEE, 66(1), pp.51-83, 1978.