size 400,400
xrange -10,10
yrange -10,10
strokecolor red
linegraph -10:1:-5:-1:3:3:10:-5
strokecolor blue
linegraph -10:-1:-5:1:3:-3:10:5
dashed
strokecolor green
linegraph -10:2:-5:-2:3:4:10:2
grid 1,1,grey
