function G = ellipse_fmincon(theta,x1,x2)
% x1 = (x1 - mean(x1))/std(x1) ;
% x2 = (x2 - mean(x2))/std(x2) ;
A = [x1.^2 x2.^2 x1.*x2 x1 x2 ones(length(x1),1)];
G = norm([A*theta(1:6)'],2);
