The document contains MATLAB code that generates various 3D surface and contour plots by defining x-y grids, calculating z-values as functions of x and y, and using functions like mesh, surf, contour3 to plot and visualize the surfaces. Different functions are used like mesh, meshc, surf, contour3 to plot the same surfaces in different visual styles. The z-values are defined as exponential, quadratic or trigonometric functions of x and y.

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)