%21. session, example 2

[X,Y] = meshgrid(-3:.2:3, -3:.2:3);
Z = (X.^2-Y.^2).*exp(-X.^2-Y.^2);

figure(1)
contour(Z,16);

figure(2)
surfc(X,Y,Z)

figure(3)
surf(X,Y,Z)

figure(4)
surfl(X,Y,Z);
shading interp;
colormap(pink);

figure(5)
mesh(X,Y,Z)
