-3 13 setxrange
-1 6 setyrange

2 1 setquadrillagestep
quadrillage

/f {4 div} def
/g {4 div 2.5 add} def

/C {0 dup f} def
/P {4 dup f} def
/D {8 dup f} def
/Q {10 dup f} def
/N {0 dup g} def
/M {2 dup g} def
/B {6 dup g} def
/A {10 dup g} def

{f} courbe
{g} courbe

[C P D Q N M B A] points

20 setfontsize
setTimesItalic
   (A) A urtext
   (B) B urtext
   (C) C urtext
   (D) D urtext
   (N) N urtext
   (M) M urtext
   (P) P urtext
   (Q) Q urtext