60 setxunit
18 setfontsize
-3 2 setxrange
-1 6 setyrange

tracerepere
marks

/f {
   Exp
} def

/g{ setxvar 
x
.5 ln
mul
Exp
} def

setTimesItalic
   (O) O drtext
   (a) 1 5.5 urtext (x) exposant 
   (a>1) 1 5.5 drtext
   (a) -2 5.5 urtext (x) exposant 
   (0<a<1) -2 5.5 drtext

2 setlinewidth

bleu
{f} courbe

rouge
{g} courbe