draw_ellipse

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   DRAW_ELLIPSE(POS, COV, COLOR) 
   Draws an ellipse in the current figure with color COLOR, 'r', 'g', 'b'...etc 
   The ellipse is drawn at position POS and defined by its covariance
   matrix COV.
   
    See also DRAW_CIRCLE, DRAWROBOT3D.

   Author: Arturo Gil. Universidad Miguel Hernández de Elche.
   email: arturo.gil@umh.es date:   05/02/2012
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0001 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
0002 %   DRAW_ELLIPSE(POS, COV, COLOR)
0003 %   Draws an ellipse in the current figure with color COLOR, 'r', 'g', 'b'...etc
0004 %   The ellipse is drawn at position POS and defined by its covariance
0005 %   matrix COV.
0006 %
0007 %    See also DRAW_CIRCLE, DRAWROBOT3D.
0008 %
0009 %   Author: Arturo Gil. Universidad Miguel Hernández de Elche.
0010 %   email: arturo.gil@umh.es date:   05/02/2012
0011 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
0012 
0013 % Copyright (C) 2012, by Arturo Gil Aparicio
0014 %
0015 % This file is part of ARTE (A Robotics Toolbox for Education).
0016 %
0017 % ARTE is free software: you can redistribute it and/or modify
0018 % it under the terms of the GNU Lesser General Public License as published by
0019 % the Free Software Foundation, either version 3 of the License, or
0020 % (at your option) any later version.
0021 %
0022 % ARTE is distributed in the hope that it will be useful,
0023 % but WITHOUT ANY WARRANTY; without even the implied warranty of
0024 % MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
0025 % GNU Lesser General Public License for more details.
0026 %
0027 % You should have received a copy of the GNU Leser General Public License
0028 % along with ARTE.  If not, see <http://www.gnu.org/licenses/>.
0029 function h = draw_ellipse(pos, cov, color)
0030 
0031 %for different DOF
0032 chi2=[6.6349    9.2103   11.3449   13.2767   15.0863   16.8119   18.4753];
0033 
0034 tita = linspace(0, 2*pi,40);
0035 CIRCLE = [cos(tita); sin(tita)];
0036 
0037 [V,D]=eig(full(cov(1:2,1:2)));
0038 ejes=sqrt(chi2(2)*diag(D));
0039 P = (V*diag(ejes))*CIRCLE;
0040 hp = line(P(1,:)+pos(1), P(2,:)+pos(2));
0041 set(hp,'Color', color);
0042