% draw paraboloid level sets with lwo line constraints

parab = '(2*x)^2 + (3*y)^2 + 10';

l1_slope = 1.5;
l1_b = -1;

l2_slope = -1/l1_slope;
l2_b = l1_b-3;

figure (1);

hold off;
surface = ezsurf(parab);

hold on;
ezplot(['-y + ' num2str(l1_slope) '*x +' num2str(l1_b)]);
ezplot(['-y + ' num2str(l2_slope) '*x +' num2str(l2_b)]);
ezcontour(parab, 30);
set(gcf, 'Color', 'White');
title('');

%bug workaround to make Z-axis appear
set(surface,'MarkerEdgeColor','none');
set(surface,'Marker','+');

%set shading
shading flat;

%plot2svg must be retrieved from http://www.zhinst.com/blogs/schwizer/
plot2svg;