|figure axe mobile stylo bloc|
figure := DrGeoCanvas new.
axe:=figure
   segment: (figure point: -5@0)
   to: (figure point: 5@0).
mobile := figure pointOnCurve: axe at: 0.1.
bloc := [:mathItem| |x|
   x := mathItem point x.
   x @ (x*x*x/25 - x)].
stylo := figure point: bloc parent: mobile.