function ra=lpcar2ra(ar)
%LPCAR2RA Convert ar filter to inverse filter autocorrelation coefs. RA=(AR)


%      Copyright (C) Mike Brookes 1997
%      Version: $Id: lpcar2ra.m,v 1.4 2007/05/04 07:01:38 dmb Exp $
%
%   VOICEBOX is a MATLAB toolbox for speech processing.
%   Home page: http://www.ee.ic.ac.uk/hp/staff/dmb/voicebox/voicebox.html
%
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%   This program is free software; you can redistribute it and/or modify
%   it under the terms of the GNU General Public License as published by
%   the Free Software Foundation; either version 2 of the License, or
%   (at your option) any later version.
%
%   This program 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 General Public License for more details.
%
%   You can obtain a copy of the GNU General Public License from
%   http://www.gnu.org/copyleft/gpl.html or by writing to
%   Free Software Foundation, Inc.,675 Mass Ave, Cambridge, MA 02139, USA.
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[nf,p1]=size(ar);
ra=zeros(nf,p1);
for i=1:p1
   ra(:,i)=sum(ar(:,1:p1+1-i).*ar(:,i:p1),2);
end