-10 5 setxrange
-8.5 8 setyrange
2 2 setmkstep
1 1 setsubtkstep
2 2 settkstep

/f {
   setxvar
   2 x mul 4 sub
   x Exp mul
} def
/f' {
   setxvar
   x Exp x 1 sub 2 mul mul
} def

.5 setlinewidth
3 settailletangente
1 (f) tangente
10 settailletangente
0 (f) tangente

tracerepere
marks
1 dup f dashpoint

/hstep 3 def
/hwidth .4 def
0 2 {f} Hachcourbe

.9 setlinewidth
{f} courbe

setTimesItalic
   (C) 2.3 dup f drtext
   (f) indice
   (T) 2 -7 cctext