www.gusucode.com > wavelet工具箱matlab源码程序 > wavelet/wavelet/@laurpoly/even.m
function E = even(P) %EVEN Even part of a Laurent polynomial. % E = EVEN(P) returns the even part E of the Laurent polynomial P. % The polynomial E is such that: % E(z^2) = [P(z) + P(-z)]/2 % % See also DYADDOWN, ODD. % M. Misiti, Y. Misiti, G. Oppenheim, J.M. Poggi 21-Mar-2001. % Last Revision 15-Jun-2003. % Copyright 1995-2004 The MathWorks, Inc. % EVEN(P) == DYADDOWN(P) %----------------------- C = P.coefs; D = P.maxDEG; E = laurpoly(C(1+mod(D,2):2:end),floor(D/2));