%21. session example 3

[X,Y] = meshgrid(-10:.5:10, -10:.5:10);
Z = sin(sqrt(X.^2+Y.^2));

figure(1)
contour(X,Y,Z,16)

figure(2)
surfl(X,Y,Z);
shading interp;
colormap(copper);
axis([-10 10 -10 10 -5 5]);

figure(3)
mesh(X,Y,Z)
axis([-10 10 -10 10 -5 5]);
