12 setxunit
7.5 setborder
90 setangle_repere
-8 10 setxrange
-7 8 setyrange
1 1 settkstep
.5 .5 setsubtkstep
2 2 setmkstep
ticks
subticks
marks
traceaxes
axesarrow
unites
/f {setxvar
   2 x mul x mul x mul 2 x mul sub 3 add x x mul x add 1 add div
} def
/g {setxvar
   2 x mul 2 sub
} def
gsave
   noir
   1.75 setlinewidth
   continu
  xmin  xmax {f} Courbe
grestore
gsave
   rouge
   .75 setlinewidth
   pointilles
   {g} courbe
grestore