-1 4 setxrange
-2.5 0.5 setyrange
50 setxunit

gsave
masque


/f {
2 dict begin
   /x exch def
   /y exch def
#rpn# x*x*y
end
} def

.5 setlinewidth
/arrowscale {.5 dup} def
.4 setgray


{f} .25 .25 .2 (->) champvecteur


/arrowscale {.75 dup} def
.7 setlinewidth
noir
traceaxes
axesarrow

1.3 setlinewidth
bleu
[xmin xmax {f} -1 -1 .5 Euler] ligne