www.pudn.com > voicebox2.zip > LPCAR2PF.M

function pf=lpcar2pf(ar,np) 
%LPCAR2PF Convert AR coefs to power spectrum PF=(AR,NP) 
% the power spectrum will contain np+2 points ranging from Dc to nyquist frequency 
% The routine is faster if NP+1 is a power of 2. 
 
%      Copyright (C) Mike Brookes 1998 
% 
%      Last modified Sun Jan  2 20:30:20 2000 
% 
%   VOICEBOX is a MATLAB toolbox for speech processing. Home page is at 
%   http://www.ee.ic.ac.uk/hp/staff/dmb/voicebox/voicebox.html 
% 
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% 
%   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 
%   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. 
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% 
 
[nf,p1]=size(ar); 
if nargin<2 np=p1-1; end 
pf=abs(rfft(ar.',2*np+2).').^(-2);