[x,y]=meshgrid(-2:0.1:2,-1:0.1:3);
     z=100*(y-x.^2).^2+(1-x).^2;
     contour(x,y,z,20)
     hold on
     plot(-1.2,2,' o ');
     text(-1.2,2,'start point')
     plot(1,1,'o')
     text(1,1,'solution')