Vector Field Examples.

> with(plots):

> f1:=y;

> f2:=-x;

> fieldplot([f1,f2],x=-1..1,y=-1..1);

> g1:=log(1+x^2);

> g2:=-log(1+y^2);

> fieldplot([g1,g2],x=-5..5,y=-5..5,grid=[10,10]);

> size := (x^2+y^2+z^2)^(1.5);

Gravitational field:

> fieldplot3d([-x/size,-y/size,-z/size],x=-2..2,y=-2..2,z=-2..2,axes=normal,grid=[4,4,4]);

>