code: public double getDouble(Integer id, Integer type)
     {
        double result = Double.longBitsToDouble(getLong(id, type));
        if (Double.isNaN(result))
        {
           result = 0;
        }
        return result;
     }
docs: This method retrieves a double of the specified type,
  belonging to the item with the specified unique ID.
  
  @param id unique ID of entity to which this data belongs
  @param type data type identifier
  @return required double data