www.pudn.com > voicebox2.zip > LPCPF2RR.M

function rr=lpcpf2rr(pf,p) 
%LPCPF2RR convert power spectrum to autocorrelation coefs RR=(PF,P) 
% Note that these will only be accurate if the power spectrum is much longer than p 
 
 
%      Copyright (C) Mike Brookes 1997 
% 
%      Last modified Tue May 12 16:20:15 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. 
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%   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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[nf,p2]=size(pf); 
if nargin<2 p=p2-2; end; 
ir=irfft(pf.').'; 
if p>p2-2 
  rr=[ir(:,1:p2-1) zeros(nf,p+2-p2)]; 
else 
  rr=ir(:,1:p+1); 
end