50 setxunit 7.5 setborder 90 setangle_repere -0.5 3 setxrange -3 3 setyrange 1 1 settkstep .5 .5 setsubtkstep 0.5 0.5 setmkstep ticks subticks marks traceaxes axesarrow /R {settvar #rpn# 3*Cos(t)-Cos(3*t) } def 0 2 pi mul settrange gsave .75 setlinewidth continu bleu (R) courbepolar grestore