www.pudn.com > voicebox2.zip > LPCLS2AR.M

function ar=lpcls2ar(ls) 
%LPCLS2AR convert line spectrum pair frequencies to ar polynomial AR=(LS) 
% input vector elements should be in the range 0 to 0.5 
 
 
%      Copyright (C) Mike Brookes 1997 
% 
%      Last modified Tue May 12 16:20:43 1998 
% 
%   VOICEBOX home page: http://www.ee.ic.ac.uk/hp/staff/dmb/voicebox/voicebox.html 
% 
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%   it under the terms of the GNU General Public License as published by 
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[nf,p]=size(ls); 
p1=p+1; 
p2 = p1*2; 
ar=zeros(nf,p1); 
for k=1:nf 
  le=exp(ls(k,:)*pi*2i); 
  lf=[1 le -1 conj(fliplr(le))]; 
  y=real(poly(lf(1:2:p2))); 
  x=real(poly(lf(2:2:p2))); 
  ar(k,:)=(x(1:p1)+y(1:p1))/2; 
end