-1 11 setxrange
-1 5 setyrange

20 setxunit

/U {0 0} def
/u {4 3} def
/V {4 4} def
/v {6 -3} def
U u addv /U' defpoint
V v addv /V' defpoint

/A {4 1} def
/B {5 3} def

quadrillage

[A B U V] points
U U' (->) line
V V' (->) line

setTimesItalic
   (A) A dltext
   (B) B dltext

<tex>
$\vec u$
</tex>
U U' milieu [1.2 dup] uctexlabel
<tex>
$\vec v$
</tex>
V V' milieu [1.2 dup] uctexlabel