%% auteur : Gilles Mora

200 setxunit
100 setyunit
%7.5 setborder
90 setangle_repere
-0.2 1.3 setxrange
-0.2 1.3 setyrange
traceaxes
axesarrow
marks


/f {setxvar
    1
} def

/fillstyle {0.9 0.9 0.9 setrgbcolor fill} def 

0.3 0.7 {f} Fillcourbe 
gsave
   noir
   2 setlinewidth
   continu
 0 1   {f} Courbe
grestore

/A0 {0.3 0} def
/A1 {0.7  0} def
/B0 {0.3 1} def
/B1 {0.7 1} def
[A0 B0] ligne
[A1 B1] ligne
pointilles
[1 0 1 1] ligne

<tex>
  $a$
</tex>
A0 [1.5 1.5]dctexlabel

<tex>
  $b$
</tex>
A1 [1.5 1.5]dctexlabel




<tex>
  $P([a~;~b])$
</tex>
0.5 0.5 [1.5 1.5]cctexlabel

<tex>
  $O$
</tex>
0 0 [1.5 1.5] dltexlabel