25 setxunit
7.5 setborder
90 setangle_repere
-5.3 5.3 setxrange
-5.3 5.3 setyrange
1 1 settkstep
.5 .5 setsubtkstep
2 2 setmkstep
ticks
subticks
marks
traceaxes
axesarrow
/R {settvar
#rpn#   4*Sin (20*t)
} def
  0  10 pi mul settrange
gsave
   0.75 setlinewidth
   continu
   orange
   (R) courbepolar
grestore