link graphics

procedure main(A)  # points, inside r, outside r in pixels - default to task values

if \A[1] == "help" then stop("Usage: plot #points inside-radius outside-radius")
points  := \A[1] | 100
outside := \A[2] | 15
inside  := \A[3] | 10
if inside > outside then inside :=: outside

wsize   := integer(2.2*outside)
wsize  <:= 150
center  := wsize/2

WOpen("size="||wsize||","||wsize,"bg=black","fg=white") | stop("Unable to open window")

until(points -:= 1) <= 0 do {
   x := ?(2*outside)-outside   # random x
   y := ?(2*outside)-outside   # and y
   if (inside <= integer(sqrt(x^2+y^2)) ) <= outside then
      DrawPoint(x + center,y + center)
   }
WDone()

end