1 setxyrapport 25 setxunit 7.5 setborder -30 30 setxrange -30 30 setyrange jpegmode /a 12 def /b 1 def /c 2 def /resolution 500 def 2 2 settkstep 1 1 setsubtkstep 2 2 setmkstep ticks traceaxes axesarrow unites 0.25 setlinewidth continu rouge /X {settvar #rpn# (a+b)*Cos(t)-c*Cos((1+a/b)*t) } def /Y {settvar #rpn# (a+b)*Sin(t)-c*Sin((1+a/b)*t) } def 0 20 pi mul {X} {Y} Courbeparam