50 setxunit
7.5 setborder
-3 5 setxrange
-3 3 setyrange
jpegmode
/a 2 def

1 1 settkstep
.5 .5 setsubtkstep
2 2 setmkstep
traceaxes
axesarrow
/R {settvar
    a 2 exp t div sqrt
} def
  .1  50 settrange
gsave
   1.75 setlinewidth
   continu
   orange
   (R) courbepolar
grestore