1. [x,y]=meshgrid(-5:.2:5);
z=(x.^2+y.^2).*exp(1-x.^2-y.^2);
mesh(x,y,z)
[x,y]=meshgrid (-5:.2:5);
z= (x.^2+y.^2).*exp(1-x.^2-y.^2);
meshc(x,y,z)
[x,y]=meshgrid(-5:.2:5);
z=(x.^2+y.^2).*exp(1-x.^2-y.^2);
surf(x,y,z)

2. [x,y]=meshgrid(-5:.2:5);
z=(x.^2+y.^2).*exp(1-x.^2-y.^2);
contour3(x,y,z,20)
[x,y]=meshgrid(-2:.25:2);
z=2-y.^2+(x.^2).*exp(1-x.^2-(0.25*y.^2));
contour3(x,y,z,20)
[x,y]=meshgrid(-5:.25:5,-1:0.2:1);
z=2-y.^2+(x.^2).*exp(1-x.^2-(0.25*y.^2));
mesh(x,y,z)

3. [x,y]=meshgrid(-5:.25:5,-1:0.2:1);
z=2-y.^2+(x.^2).*exp(1-x.^2-(0.25*y.^2));
meshc(x,y,z)
[x,y]=meshgrid(-5:.25:5,-5:.2:5);
z=2-y.^2+(x.^2).*exp(1-x.^2-(0.25*y.^2));
surface(x,y,z)
[x,y]=meshgrid(-2:.25:2,-5:.2:5);
z=cos((x.^2+y.^2)/4);
surface(x,y,z)

4. [x,y]=meshgrid(-2:.25:2,-5:.2:5);
z=cos((x.^2+y.^2)/4);
mesh(x,y,z)
[x,y]=meshgrid(-2:.25:2,-5:.2:5);
z=cos((x.^2+y.^2)/4);
meshc(x,y,z)
[x,y]=meshgrid(-2:.25:2,-5:.2:5);
z=cos((x.^2+y.^2)/4);
contour3(x,y,z,30)