... have similar computationalstructures, none of them appears to have a substantial speedadvantage [21]. As a practical matter, highly optimized real-input FFT libraries are available from many ... entries per row and column)that allows an iterative calculation of HNx,foranyx ∈ RN.Since the matrices are sparse and orthogonal, the factoriza-tion of HNgenerates a fast and low arithmetic ... 15–23, Orlando, Fla, USA, July 2002.[2] P.Yan,Y.L.Mo,andH.Liu,“Imagerestorationbasedonthediscrete fraction Fourier transform,” in Image Matching and Analysis, B. Bhanu, J. Shen, and T. Zhang, Eds.,...