25 setxunit 7.5 setborder 90 setangle_repere -5 5 setxrange -5 5 setyrange 1 1 settkstep .5 .5 setsubtkstep 2 2 setmkstep ticks subticks marks traceaxes axesarrow /R {settvar #rpn# sqrt(2*cos(2*t)) } def 0 10 pi mul settrange gsave 1.75 setlinewidth continu bleu (R) courbepolar grestore