-3.5 4 setxrange
-.1 .7 setyrange

40 setxunit
.3 setxyrapport

10 setfontsize
/sigma 1 def
/m 0 def
/t1 -1.67 def
/t2 1.67 def

/f {
   m sub sigma div
   dup mul
   -2 div
   Exp
   1
   2 pi mul sqrt sigma mul   
   div mul
}  def

traceaxes
axesarrow
t1 t2 {f} Hachcourbe
t1 xtick
t2 xtick

t1 dup f point
t2 dup f point

gsave
newpath
   pointilles
   [t1 dup f dupp projx] ligne
   [t2 dup f dupp projx] ligne
stroke
grestore

1.2 setlinewidth
{f} courbe

setTimesItalic
   (O) 0 0 dltext
   (-t) t1 0 dctext
setTimesItalic
   (t) t2 0 dctext

/dx_boxit 2 def
/dy_boxit 2 def
<tex>
$P (-t \leq T \leq t) = 2\Pi (t) - 1$
</tex>

boxit
xmax .5 mul ymax .75 mul cctexlabel