cdm/src/main/java/ucar/nc2/time/CalendarPeriod.java
public double getConvertFactor(CalendarPeriod from) {
    if (field == CalendarPeriod.Field.Month || field == CalendarPeriod.Field.Year) {
      log.warn(" CalendarDate.convert on Month or Year");
    }

    return (double) from.millisecs() / millisecs();
  }
public double getConvertFactor(CalendarPeriod from) {
    if (field == CalendarPeriod.Field.Month || field == CalendarPeriod.Field.Year) {
      log.warn(" CalendarDate.convert on Month or Year");
    }

    return (double) from.millisecs() / millisecs();
  }
Get the conversion factor of the other CalendarPeriod to this one
@param from convert from this
@return conversion factor, so that getConvertFactor(from) * from = this