%% auteur :
tracerepere
quadrillage
marks
/A {1 2} def
A point
/B {2 3} def
B  times2
rouge
{1 mul 1 add} courbe

tracerepere
quadrillage
marks
/A {3 4} def
A point
/B {4 6} def
B  times2
rouge
{1 mul 1 add} courbe