%% auteur : Péric
-3 10 setxrange
-1 2.5 setyrange
%20 setxunit
18 setfontsize

traceOx
axeOxarrow

xticks
0 xtick
%[-1 3 7] {xmark} apply
/a {3} def
(0) 0 -0.2 [a dup] dctext
(-1) -1 -0.2 [a dup] dctext
(3) 3 -0.2 [a dup] dctext
(7) 7 -0.2 [a dup] dctext
(4) 1 2 [a dup] cctext
(4) 5 2 [a dup] cctext

/arrowscale {2 dup} def
/angleA 120 def
/angleB 60 def
3 0.5 -1 0.5 (->) pccurve


/angleA 60 def
/angleB 120 def
3 0.5 7 0.5 (->) pccurve

3 setlinewidth
[-1 0 7 0] ([-]) ligne