code: public Vector getCentralPoint() {
  		Vector arc = new Vector();
  		if (empieza <= acaba) {
  			addNode(arc, (empieza+acaba)/2.0);
  		} else {
  			addNode(arc, empieza);
  			double alfa = 360-empieza;
  			double beta = acaba;
  			double an = alfa + beta;
  			double mid = an/2.0;
  			if (mid<=alfa) {
  				addNode(arc, empieza+mid);
  			} else {
  				addNode(arc, mid-alfa);
  			}
  		}
  		return arc;
  	}
docs: Method that allows to obtain a set of points located in the central zone of
  this arc object