public PlaSegmentFloat diagonal_corner_segment(){
  if (is_empty())   return null;
  PlaPointFloat first_corner=corner_approx(0);
  PlaPointFloat last_corner=corner_approx(border_line_count() / 2);
  return new PlaSegmentFloat(first_corner,last_corner);
}

public PlaSegmentFloat diagonal_corner_segment ( ) { if ( is_empty ( ) ) return null ; PlaPointFloat first_corner = corner_approx ( 0 ) ; PlaPointFloat last_corner = corner_approx ( border_line_count ( ) / 2 ) ; return new PlaSegmentFloat ( first_corner , last_corner ) ; }
returns a line segment consisting of an approximations of the corners with index 0 and corner_count / 2 .
