-5 5 setxrange -7 5 setyrange -5 5 setyrange 30 setxunit gsave masque quadrillage /f { 2 dict begin /y exch def /x exch def %% x -2 x mul y mul add #rpn# x - 2*x*y end } def .5 setlinewidth /arrowscale {.5 dup} def .4 setgray {f} .25 .25 .1 champvecteur /arrowscale {.75 dup} def .7 setlinewidth noir tracerepere 1 setlinewidth %% on represente quelques solutions -3 1 7 { /i exch def bleu [{f} 1 i 4 div .1 euler] ligne } for grestore #tex# $y' + 2xy = x$ 0 -6 [2 dup] cctexlabel