-5 14 setyrange
-4 7 setxrange
2 setxyrapport
20 setxunit
2 setymkstep
1 2 setsubtkstep
1 2 setquadrillagestep
quadrillage
/unites {} def
tracerepere
marks

/f {
   setxvar
   x dup mul -2 x mul add -3 add
} def

[-3 5] {dup f} apply dashpoints

1 setlinewidth
-3 5 {f} Courbe