public double add(int index, double delta) {
        updated = true;
        int newIndex = getIndex(index);
        return (newIndex == -1) ? 0 : doubleVector.add(newIndex, delta);
    }
public double add ( int index , double delta ) { updated = true ; int newIndex = getIndex ( index ) ; return ( newIndex == - 1 ) ? 0 : doubleVector . add ( newIndex , delta ) ; }
{@inheritDoc}