25 setxunit 7.5 setborder -8 8 setxrange -8 8 setyrange jpegmode /a 4.5 def /b 1.5 def /c 0.75 def 2 2 settkstep 1 1 setsubtkstep 2 2 setmkstep ticks traceaxes axesarrow 0.75 setlinewidth continu bleu /X {settvar #rpn# (a-b)*(cos(t))*(cos(t))+c*cos((a-b)*t/b) } def /Y {settvar #rpn# (a-b)*sin(t)+c*sin((a-b)*t/b) } def 0 300 pi mul {X} {Y} Courbeparam