www.pudn.com > box.rar > 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 
%      Version: $Id: lpcar2pf.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 
% 
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% 
%   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. 
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% 
 
[nf,p1]=size(ar); 
if nargin<2 np=p1-1; end 
pf=abs(rfft(ar.',2*np+2).').^(-2);