%                          [y, ddotx, Dx, xTy] = PopK(d,x,K,lpq)
% POPK  Implements the quadratic operator for symmetric cones K.
%
% SEE ALSO sedumi
% **********  INTERNAL FUNCTION OF SEDUMI **********
function [y, ddotx, Dx, xTy] = PopK(d,x,K,lpq)
 %  
 %   This file is part of SeDuMi 1.05
 %   Copyright (C) 2001 Jos F. Sturm
 %     Dept. Econometrics & O.R., Tilburg University, the Netherlands.
 %     Supported by the Netherlands Organization for Scientific Research (NWO).
 %   Affiliation SeDuMi 1.03 and 1.04Beta (2000):
 %     Dept. Quantitative Economics, Maastricht University, the Netherlands.
 %   Affiliations up to SeDuMi 1.02 (AUG1998):
 %     CRL, McMaster University, Canada.
 %     Supported by the Netherlands Organization for Scientific Research (NWO).
 % 
 %   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 should have received a copy of the GNU General Public License
 %   along with this program; if not, write to the Free Software
 %   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 %
 if nargin < 4
   lpq = 0;
 end
% LP / Lorentz
 i1 = K.mainblks(1); i2 = K.mainblks(2);
 y = [d.l .* x(1:i1-1); -d.det .* x(i1:i2-1); qblkmul(d.det,x,K.qblkstart)];
 ddotx = (d.q1).*x(i1:i2-1) + ddot(d.q2,x,K.qblkstart);
% PSD:
 Dx = psdscale(d,x,K);
 if lpq == 0
   y = [y; psdscale(d,Dx,K,1)];               % Include PSD-part
 end
% xTy:
 if nargout >= 4
   xTy = x(1:K.lq)'*y(1:K.lq) + norm(ddotx)^2 + norm(Dx)^2;
 end
