v_lpcar2ls

V_LPCAR2LS convert ar polynomial to line spectrum pair frequencies LS=(AR)
 output vector elements will be in range 0 to 0.5
 the returned vector will be of length p

0001 function ls=v_lpcar2ls(ar)
0002 %V_LPCAR2LS convert ar polynomial to line spectrum pair frequencies LS=(AR)
0003 % output vector elements will be in range 0 to 0.5
0004 % the returned vector will be of length p
0005 
0006 % This routine is nowhere near as efficient as it might be
0007 
0008 
0009 %      Copyright (C) Mike Brookes 1997
0010 %      Version: $Id: v_lpcar2ls.m 10865 2018-09-21 17:22:45Z dmb $
0011 %
0012 %   VOICEBOX is a MATLAB toolbox for speech processing.
0013 %   Home page: http://www.ee.ic.ac.uk/hp/staff/dmb/voicebox/voicebox.html
0014 %
0015 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
0016 %   This program is free software; you can redistribute it and/or modify
0017 %   it under the terms of the GNU General Public License as published by
0018 %   the Free Software Foundation; either version 2 of the License, or
0019 %   (at your option) any later version.
0020 %
0021 %   This program is distributed in the hope that it will be useful,
0022 %   but WITHOUT ANY WARRANTY; without even the implied warranty of
0023 %   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
0024 %   GNU General Public License for more details.
0025 %
0026 %   You can obtain a copy of the GNU General Public License from
0027 %   http://www.gnu.org/copyleft/gpl.html or by writing to
0028 %   Free Software Foundation, Inc.,675 Mass Ave, Cambridge, MA 02139, USA.
0029 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
0030 
0031 [nf,p1]=size(ar);
0032 p = p1-1;
0033 p2 = fix(p/2);
0034 d=0.5/pi;
0035 
0036 if rem(p,2)        % odd order
0037   for k=1:nf
0038     aa=[ar(k,:) 0];
0039     r = aa + fliplr(aa);
0040     q = aa - fliplr(aa);
0041     fr = sort(angle(roots(r)));
0042     fq = [sort(angle(roots(deconv(q,[1 0 -1])))); 0];
0043     f = [fr(p2+2:p+1).' ; fq(p2+1:p).'];
0044     f(p+1) = [];
0045     ls(k,:) = d*f(:).';
0046   end
0047 else
0048   for k=1:nf
0049     aa=[ar(k,:) 0];
0050     r = aa + fliplr(aa);
0051     q = aa - fliplr(aa);
0052     fr = sort(angle(roots(deconv(r,[1 1]))));
0053     fq = sort(angle(roots(deconv(q,[1 -1]))));
0054     f = [fr(p2+1:p).' ; fq(p2+1:p).'];
0055     ls(k,:) = d*f(:).';
0056   end
0057 end