www.pudn.com > voicebox2.zip > LPCAR2RR.M

function rr=lpcar2rr(ar,p) 
%LPCAR2RR Convert autoregressive coefficients to autocorrelation coefficients RR=(AR,P) 
% The routine calculated the autocorrelation coefficients of the signal 
% that results from feeding unit-variance, zero-mean noise into the all-pole filter 
% Input:   ar(:,n+1)  Autoregressive coefficients including 0'th coefficient 
% Output:  rr(:,p+1)    Autocorrelation coefficients including 0'th order coefficient 
% If p is not specified it is taken to be n 
 
 
%      Copyright (C) Mike Brookes 1997 
% 
%      Last modified Tue May 12 15:57:56 1998 
% 
%   VOICEBOX 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. 
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%   You can obtain a copy of the GNU General Public License from 
%   ftp://prep.ai.mit.edu/pub/gnu/COPYING-2.0 or by writing to 
%   Free Software Foundation, Inc.,675 Mass Ave, Cambridge, MA 02139, USA. 
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k=ar(:,1).^(-2); 
if nargin>1 
   rr=lpcrf2rr(lpcar2rf(ar),p).*k(:,ones(1,p+1)); 
else 
   rr=lpcrf2rr(lpcar2rf(ar)).*k(:,ones(1,size(ar,2))); 
end