public void setXY(double x, double y) {
   xaxis.setLocation(y); // Added by Paco
   yaxis.setLocation(x); // Added by Paco
 }
 public void setX(double x) {
   yaxis.setLocation(x); // Added by Paco
 }
 public void centerAxes(DrawingPanel panel) {
   xaxis.setLocation((panel.getYMax() + panel.getYMin()) / 2);
   yaxis.setLocation((panel.getXMax() + panel.getXMin()) / 2);
 }