docs: public double sqrDistance(Point2D pt2D)
  	{
  		double dx = 0;
  		double dy = 0;
  		double nn;
  
  		nn = xmin - pt2D.x;
  		if (nn > dx)
  			dx = nn;
  
  		nn = ymin - pt2D.y;
  		if (nn > dy)
  			dy = nn;
  
  		nn = pt2D.x - xmax;
  		if (nn > dx)
  			dx = nn;
  
  		nn = pt2D.y - ymax;
  		if (nn > dy)
  			dy = nn;
  
  		return dx * dx + dy * dy;
  	}