IFS Fern

SCREEN 13

WINDOW (-5, 0)-(5, 10)
RANDOMIZE TIMER

DO

  SELECT CASE RND

    CASE 0 TO .01
      nextx = 0
      nexty = .16 * y
    CASE .01 TO .08
      nextx = .2 * x - .26 * y
      nexty = .23 * x + .22 * y + 1.6
    CASE .08 TO .15
      nextx = -.15 * x + .28 * y
      nexty = .26 * x + .24 * y + .44
    CASE ELSE
      nextx = .85 * x + .04 * y
      nexty = -.04 * x + .85 * y + 1.6

  END SELECT

  IF RND < .5 THEN c = 2 ELSE c = 10
  PSET (x, y), c

  x = nextx
  y = nexty
  i = i + 1

LOOP WHILE INKEY$ = ""