-2 3 setxrange
-1 9 setyrange

2 setxyrapport

/f {
   dup		% x, x
   3 mul	% x, 3x
   2 sub	% x, 3x-2
   mul		% 3x^2-2x
   1 add
}  def

tracerepere
marks
0 dup f point
-1 dup f dashpoint
1 dup f dashpoint

1.2 setlinewidth
{f} courbe

setTimesItalic
   (O) 0 0 dltext