public int upper_y_value(int p_x){
  int result=Math.min(oct_uy,p_x - oct_ulx);
  return Math.min(result,oct_urx - p_x);
}

public int upper_y_value ( int p_x ) { int result = Math . min ( oct_uy , p_x - oct_ulx ) ; return Math . min ( result , oct_urx - p_x ) ; }
computes the y value of the upper boundary of this octagon at p_x
