%  Set up cylindrical coords.

r = linspace(0,1,20);
theta = linspace(0,2*pi,20);
z = linspace(0,1,20);

%  Hold theta fixed to get a half-plane.

[r2,z2] = meshgrid(r,z);
[x,y,z] = pol2cart(pi,r2,z2);
figure(1)
surf(x,y,z), axis([-1 1 -1 1 0 1]), pause, hold on

%  Hold r fixed to get a cylinder

[theta2,z2] = meshgrid(theta,z);
[x,y,z] = pol2cart(theta2,1,z2);
s = surface(x,y,z);
mesh(x,y,z), alpha(0.5), title('Cylindrical Coordinates'), pause, hold off

%  Set up spherical coords.

phi = linspace(0,2*pi,20);
theta=linspace(-pi/2,pi/2,20);
r=linspace(0,1,20);

%  Hold theta fixed to get a cone.

[phi2,r2] = meshgrid(phi,r);
[x,y,z] = sph2cart(phi2,pi/4,r2);
figure(1)
surf(x,y,z), pause, hold on;

%  Hold phi fixed to get a half-plane.

[theta2,r2] = meshgrid(theta,r);
[x,y,z] = sph2cart(pi,theta2,r2);
surf(x,y,z), pause,

%  Hold r fixed to get a sphere.

[theta2,phi2] = meshgrid(theta,phi);
[x,y,z] = sph2cart(phi2,theta2,1);
s = surface(x,y,z);
mesh(x,y,z), alpha(0.5), title('Spherical Coordinates')