public Coordinate getCoordinate(int index) {
      int grpIndex = coordIndex.get(index);
      return group.coords.get(grpIndex);
    }
public Coordinate getCoordinate(int index) {
      int grpIndex = coordIndex.get(index);
      return group.coords.get(grpIndex);
    }
public Coordinate getCoordinate ( int index ) { int grpIndex = coordIndex . get ( index ) ; return group . coords . get ( grpIndex ) ; }
get the ith coordinate
get the ith coordinate