Source
%% auteur : 

%% auteur : Gilles Mora
-4 4 setxrange
-4 7 setyrange
60 setxunit
60 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 -3} def
/B{-2 1} def
/C{-1 2} def
/D{1 1} def
/E{2 2} def
/F{3 6} def
/M{2.4 3.15}def


1.3 setlinewidth
[A{60 dir} .. B .. C{right} .. D{right} .. E .. M .. F] draw
[A B F] 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>
-3 -2 [1.5 dup] dctexlabel