Calculate the month and day for a specified day number of a year. A day number is the number of days since 1-1 of a Year. A day number is not equal to a date number, a date number uniquely identifies a day since 1-1-1.
This predicate is located in the file 'datetime.txt', use ensure_loaded/1 to include this file.
see also: age/7 day_number/4 day_of_week/2 datetime module decode_date/4 decode_datetime/7 decode_time/4 encode_date/4 encode_datetime/7 encode_time/2 encode_time/3 encode_time/4 ensure_loaded/1 first_week/2 leap_year/1 length_month/3 monday_of_week/3 monday_of_week/5 next_week/4 num_weeks_in_year/2 prev_week/4 start_of_week/3
| Example | |
| reverse_day_number(1998, 100, Month, Day). | The day number for the first day of a year is 1, this number is unified with DayNum, DayNum = 1 |
| reverse_day_number(2000, 34, Month, Day). | Succeeds because the daynumber for 31 Jan 2000 is 31. |
| reverse_day_number(2000, 34, 5, DayNum). | The day number for the last day of the year 2000 is 366, this number is unified with DayNum, DayNum = 366 |
| Exceptions | |
| The Year and DayNumber parameters are not integers | a type_error(evaluable, Value) exception is thrown, Value is unified with the incorrect argument |
| The Month and/or Day parameters are not integers nor variables | a type_error(evaluable, Value) exception is thrown, Value is unified with the incorrect argument |