www.pudn.com > voicebox2.zip > LPCRF2AA.M

function aa=lpcrf2aa(rf) 
%LPCRF2AA Convert reflection coefficients to area function AA=(RF) 
%The areas are normalised so that aa(p+2)=1: the effective area of the free air beyond the lips. 
% aa(1) is the area of the glottis. This will be zero if rf(:,1)=1. 
 
 
%      Copyright (C) Mike Brookes 1997 
% 
%      Last modified Tue May 12 16:19:43 1998 
% 
%   VOICEBOX 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 
%   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. 
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% 
 
aa = fliplr(cumprod([ones(1,size(rf,1)); fliplr((1-rf)./(1+rf)).']).');