-5 5 setxrange
-7 5 setyrange
-5 5 setyrange
30 setxunit

gsave
masque
quadrillage

/f {
   exch pop dup mul 1 add
} def

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

{f} .25 .25 .1 champvecteur

/arrowscale {.75 dup} def
.7 setlinewidth
noir
tracerepere

.5 setlinewidth
orange
%% on represente quelques solutions
-7 1 7 {
   /i exch def
   [{f} i 1 .01 euler] ligne
} for

grestore

#tex# $y' = 1 + y^2$
0 -6 [2 dup] cctexlabel