static int invertWeekdayNum(ByDay weekdayNum, DayOfWeek dow0, int nDays) {
		//how many are there of that week?
		return countInPeriod(weekdayNum.getDay(), dow0, nDays) + weekdayNum.getNum() + 1;
	}
static int invertWeekdayNum ( ByDay weekdayNum , DayOfWeek dow0 , int nDays ) { return countInPeriod ( weekdayNum . getDay ( ) , dow0 , nDays ) + weekdayNum . getNum ( ) + 1 ; }
<p>
Converts a relative week number (such as {@code -1SU}) to an absolute
week number.
</p>
<p>
For example, the week number {@code -1SU} refers to the last Sunday of
either the month or year (depending on how this method was called). So if
there are 5 Sundays in the given period, then given a week number of
{@code -1SU}, this method would return 5. Similarly, {@code -2SU} would
return 4.
</p>
@param weekdayNum the weekday number (must be a negative value, such as
{@code -1SU})
@param dow0 the day of the week of the first day of the week or month
@param nDays the number of days in the month or year
@return the absolute week number