-5 10 setxrange
-4 7 setyrange

/unites {} def
tracerepere
2 2 setmkstep
marks

/f {setxvar
#rpn# x - (x+1) / Exp (x)
} def
/f' {setxvar
#rpn# (x + Exp (x)) / Exp (x)
} def

.5 setlinewidth
/dotscale {.6 dup} def
/arrowscale {.6 dup} def
5 settailletangente
-1 (f) tangente
3 settailletangente
-1 0 .01 {dup Exp add} dich_solve /alpha exch def
alpha (f) tangente

gsave
   pointilles
   [alpha 0 alpha dup f] ligne
grestore

alpha xtick

.8 setlinewidth
{f} courbe
mixte
{} courbe

#tex# $\cal C$
-1.8 dup f cltexlabel

setTimesItalic
   (O) O drtext
   (D) -3 dup bltext
   (I) -1 dup cltext
setSymbol
   (a) alpha 0 uctext