15 setxunit 5 setborder -10 10 setxrange -10 10 setyrange jpegmode /a 2 def /b 1 def /c 2 def /resolution 500 def /quadrillagegray 0.4 def 1 setquadrillagexstep 1 setquadrillageystep quadrillage 1 1 settkstep 1 1 setsubtkstep 2 2 setmkstep ticks traceaxes axesarrow unites 0.75 setlinewidth continu bleu /X {settvar #rpn# (a+b) * Cos (t) - c * Cos (t*(2+a/b)) } def /Y {settvar #rpn# (a+b) * Sin (t) - c * Sin (t*(2+a/b)) } def 0 20 pi mul {X} {Y} Courbeparam