www.gusucode.com > 时间序列分析工具箱 - tsa源码程序 > tsa/ucp.m
function b=ucp(c) % UCP(C) tests if the polynomial C is a Unit-Circle-Polynomial. % It tests if all roots lie inside the unit circle like % B=ucp(C) does the same as % B=all(abs(roots(C))<1) but much faster. % The Algorithm is based on the Jury-Scheme. % C are the elements of the Polynomial % C(1)*X^N + ... + C(N)*X + C(N+1). % % REFERENCES: % O. Foellinger "Lineare Abtastsysteme", Oldenburg Verlag, Muenchen, 1986. % F. Gausch "Systemtechnik", Textbook, University of Technology Graz, 1993. % This library is free software; you can redistribute it and/or % modify it under the terms of the GNU Library General Public % License as published by the Free Software Foundation; either % Version 2 of the License, or (at your option) any later version. % % This library is distributed in the hope that it will be useful, % but WITHOUT ANY WARRANTY; without even the implied warranty of % MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU % Library General Public License for more details. % % You should have received a copy of the GNU Library General Public % License along with this library; if not, write to the % Free Software Foundation, Inc., 59 Temple Place - Suite 330, % Boston, MA 02111-1307, USA. % Version 2.62 % 07.04.1999 % Copyright (C) 1996-1999 by Alois Schloegl <a.schloegl@ieee.org> % [lr,lc] = size(c); % JURY-Scheme b=ones(lr,1); lambda=zeros(lr,1); while (lc > 1), lambda = c(:,lc)./c(:,1); % disp([lc,size(lambda), sum(b),toc]); % ratio must be less then 1 b = b & (abs(lambda) < 1); % and reduced polynomial must be a UCP, too. c(:,1:lc-1) = c(:,1:lc-1) - lambda(:,ones(1,lc-1)).*c(:,lc:-1:2); lc = lc-1; end;