function ACF=poly2ac(a,efinal)% converts an AR polynomial into an autocorrelation sequence% [R] = poly2ac(a [,efinal] );%% see also ACOVF ACORF AR2RC RC2AR DURLEV AC2POLY, POLY2RC, RC2POLY, RC2AC, AC2RC, POLY2AC% %	Version 2.90	last revision 10.04.2002%	Copyright (C) 1996-2002 by Alois Schloegl <a.schloegl@ieee.org>% 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.fprintf(2,'ERROR: POLY2AC does not work yet. Sorry\n');return;mfilename='POLY2AC';if ~exist('rc2ar','file')        fprintf(2,'Error %s: RC2AR.M not found. \n Download TSA toolbox from http://www.dpmi.tu-graz.ac.at/~schloegl/matlab/tsa/\n',mfilename);        return;end;[AR,RC,PE] = ar2rc(poly2ar(a));%[AR,RC,PE,ACF] = rc2ar(RC);if nargin<2, efinal=PE(:,size(PE,2)); end;ACF=zeros(size(a));ACF(:,1) = 1;for k=2:size(a,2),        ACF(:,k)=sum(AR(:,1:k-1).*ACF(:,k-(1:k-1)),2);end;R0=(sum(AR(:,1:k-1).*ACF(:,2:size(ACF,2)),2)+1).*efinal; %PE(:,size(PE,2));ACF = ACF.*R0(:,ones(1,size(ACF,2)));%ACF=ACF*efinal*PE(1)/PE(length(PE));