function D = DistanceToConicApprx(XY,XYproj,A)

%  Approximate distance from the point to conic
%  through the previously computed projected point
%   (helps evaluate the quality of the projection)

%      Nikolai Chernov,  July 2012

Penalty = 1000;
n = size(XY,1);

for i=1:n
    if ~isfinite(norm(XYproj(i,:)))
        XYproj(i,:) = [100 100];
    end
end

E0 = abs(A(1)*XYproj(:,1).*XYproj(:,1) + 2*A(2)*XYproj(:,1).*XYproj(:,2) +...
         A(3)*XYproj(:,2).*XYproj(:,2) + 2*A(4)*XYproj(:,1) + 2*A(5)*XYproj(:,2) + A(6));
E1 = 2*sqrt((A(1)*XYproj(:,1)+A(2)*XYproj(:,2)+A(4)*ones(n,1)).^2 +...
            (A(2)*XYproj(:,1)+A(3)*XYproj(:,2)+A(5)*ones(n,1)).^2);
D = sqrt(sum((XYproj-XY).^2,2)) + Penalty*E0./E1;

end