See Section 26.6.4 for vectors in the plane.
The vector command returns and draws vectors. It can take its arguments in two different ways.
| vector([1,2,3]) |
| vector(point(-1,0,0),point(0,1,2)) |
or:
| vector([-1,0,0],[0,1,2]) |
| V:=vector([-1,0,0],[0,1,2]); vector(point(-1,2,0),V) |