public ExprValue mod(ExprValue other){
		switch (dataType){
		case Long:
			if (other.dataType == DataType.Long){
				setLong(getLong() % other.getLong());
				return this;
			}
		}
		throw new FormulaException("Can not mod value between "
				+ dataType.toString() + " and " + other.dataType.toString());		
	}