x = -1 : 0.01 : 1;
y = 1./(25*(x.^2) + 1);

plot(x, y, 0, 1, 'r*');

[x, y] = meshgrid(-10:0.5:10, -10:0.5:10);
z = @(a,b) a.^2+b.^2;
subplot(2,1,1);
surf(x, y, z(x, y));
hold on
colormap(hot);
plot3(0,0,z(0,0), 'g*', 'MarkerSize', 100);
subplot(2,1,2);
[C, h] = contour(x,y,z(x,y));
%axis('square');
dx = [-5, -2, -2, 0];
dy = [-3, -3, 0, 0];
hold on;
plot(dx(1), dy(1), 'r*');
text(dx(1), dy(1), 'START');
hold on;
plot(dx(4), dy(4), 'g*');
text(dx(4), dy(4), 'STOP');
hold on;
plot(dx(2:end-1), dy(2:end-1), 'go');
hold on;
for i = 1 : 3
    line([dx(i), dx(i+1)], [dy(i) , dy(i+1)]);
end

clabel(C, h);