%% auteur : 
-4 7 setxrange
-1.5 5 setyrange
50 setxunit
50 setyunit

/quadrillagewidth[.7 .4 .1] def
[1 1 .5 .5 .5 .5]{.7 setgray} Quadrillage

1.2 setlinewidth
%0.5 0.5 setsubtkstep
traceaxes
ticks
marks
tracerepere
axesarrow

/A{-3 -1} def
/B{-2 0} def
/C{-1 3} def
/D{0 4} def
/E{1 3} def
/F{3 0} def
/G{4 -1} def
/H{5 0} def
/I{6 1} def
1.3 setlinewidth
[A{60 dir} .. B .. C .. D{right} .. E .. F .. G{right} .. H .. I] draw
[A B C D E F G H I] points


setTimes
%(1) 1 0 [1.5 1.5] dtext
%(1) 0 1 [1.5 1.5] ltext
(O) O [1.5 1.5] dltext
setTimesItalic
   (x) xmax 0 (-10 0) ultext
   (y) 0 ymax  (0 -10) drtext
<tex>
$C_f$
</tex>
5.5 1.2 [1.5 dup] dctexlabel
/g {setxvar
-0.5 x mul 2.5 add
} def
{g} courbe


<tex>
$C_g$
</tex>
-3.5 4.7 [1.5 dup] dctexlabel