www.gusucode.com > wavelet工具箱matlab源码程序 > wavelet/wavelet/orfilen4.m
function [LO_D,HI_D,LO_R,HI_R] = orfilen4(beta) %ORFILEN4 Orthogonal filters of length 4. % [LO_D,HI_D,LO_R,HI_R] = ORFILEN4(R) computes the % four filters associated with the scaling filter F. % The filter F is of length 4 and its coefficients % depend on the real R: % F = [R*(R-1) , 1-R , 1+R , R*(R+1)] / (sqrt(2)*(1+R^2)) % % The four output filters are: % LO_D = decomposition low-pass filter % HI_D = decomposition high-pass filter % LO_R = reconstruction low-pass filter % HI_R = reconstruction high-pass filter. % % N.B.: For R = -1, 0, and 1 the construction degenerates % and gives the Haar filters. For R = -1/sqrt(3), the % filters corresponds to the db2 wavelet filters. % M. Misiti, Y. Misiti, G. Oppenheim, J.M. Poggi 19-Jun-2000. % Last Revision: 07-Jul-2003. % Copyright 1995-2004 The MathWorks, Inc. if isinf(beta) beta = sign(beta)*1E12; end gamma = sqrt(2)*(1+beta.^2); F = zeros(1,4); F(1) = beta.*(beta-1)./gamma; F(2) =(1-beta)./gamma; F(3) =(1+beta)./gamma; F(4) = beta.*(beta+1)./gamma; [LO_D,HI_D,LO_R,HI_R] = orthfilt(F);