autocrop
-.2 5 setxrange
-.5 1.2 setyrange

0 5 setxrange
0 1.2 setyrange

50 setxunit
100 setyunit

/t .6 def
/lambda .7 def
/f {
   lambda mul neg Exp 
} def


.6 setlinewidth
[0 1 1 lambda div 0] ligne
1 setlinewidth 
0 xmax {f} Courbe
1 ymark

traceaxes
axesarrow
0 xmark

setTimesItalic
   (y) 0 ymax drtext
   (t) xmax 0 dltext

<tex>
$y = R (t)$
</tex>
1.5 dup f urtexlabel

<tex>
$1/\lambda $
</tex>
1 lambda div 0 dctexlabel
1 lambda div xtick