>	plot3d(r^2,r=0..10,theta=0..2*Pi,coords=z_cylindrical);

>	plot3d(x^2+y^2,x=-2..2,y=-2..2);

>	plot3d(x^2-y^2,x=-2..2,y=-2..2);

>

>	plot3d([cos(t)+v*sin(t), sin(t)-v*cos(t), v],t=0..2*Pi, v=-1..1);

>	plot3d(sqrt(r^2-1),r=1..2,theta=0..2*Pi,coords=z_cylindrical);

>	plot3d(sqrt(z^2-1),theta=0..2*Pi,z=-3..3,coords=cylindrical,numpoints=10000);

>