DEFDBL A-H, O-Z
  DEFINT I-N
  SCREEN 12
  CLS
  N = 500
  ux = 50
  FOR i = -10 TO N
      x = i
      u = 3 + x / N
      ux = ux + 1
      y = .5
      FOR j = 0 TO 500
          y = u * y * (1! - y)
      NEXT j
      FOR j = 1 TO 400
          y = u * y * (1! - y)
          PSET (ux, 400 - y * 400)
      NEXT j
  NEXT i
  dummy$ = INPUT$(1)
  CLS
  END