Calculation Gregorian easter date for given year >>> gauss_easter(2007) datetime.datetime(2007, 4, 8, 0, 0, tzinfo=datetime.timezone.utc) >>> gauss_easter(2008) datetime.datetime(2008, 3, 23, 0, 0, tzinfo=datetime.timezone.utc) >>> gauss_easter(2020) datetime.datetime
(year: int)
| 7 | |
| 8 | |
| 9 | def gauss_easter(year: int) -> datetime: |
| 10 | """ |
| 11 | Calculation Gregorian easter date for given year |
| 12 | |
| 13 | >>> gauss_easter(2007) |
| 14 | datetime.datetime(2007, 4, 8, 0, 0, tzinfo=datetime.timezone.utc) |
| 15 | |
| 16 | >>> gauss_easter(2008) |
| 17 | datetime.datetime(2008, 3, 23, 0, 0, tzinfo=datetime.timezone.utc) |
| 18 | |
| 19 | >>> gauss_easter(2020) |
| 20 | datetime.datetime(2020, 4, 12, 0, 0, tzinfo=datetime.timezone.utc) |
| 21 | |
| 22 | >>> gauss_easter(2021) |
| 23 | datetime.datetime(2021, 4, 4, 0, 0, tzinfo=datetime.timezone.utc) |
| 24 | """ |
| 25 | metonic_cycle = year % 19 |
| 26 | julian_leap_year = year % 4 |
| 27 | non_leap_year = year % 7 |
| 28 | leap_day_inhibits = math.floor(year / 100) |
| 29 | lunar_orbit_correction = math.floor((13 + 8 * leap_day_inhibits) / 25) |
| 30 | leap_day_reinstall_number = leap_day_inhibits / 4 |
| 31 | secular_moon_shift = ( |
| 32 | 15 - lunar_orbit_correction + leap_day_inhibits - leap_day_reinstall_number |
| 33 | ) % 30 |
| 34 | century_starting_point = (4 + leap_day_inhibits - leap_day_reinstall_number) % 7 |
| 35 | |
| 36 | # days to be added to March 21 |
| 37 | days_to_add = (19 * metonic_cycle + secular_moon_shift) % 30 |
| 38 | |
| 39 | # PHM -> Paschal Full Moon |
| 40 | days_from_phm_to_sunday = ( |
| 41 | 2 * julian_leap_year |
| 42 | + 4 * non_leap_year |
| 43 | + 6 * days_to_add |
| 44 | + century_starting_point |
| 45 | ) % 7 |
| 46 | |
| 47 | if days_to_add == 29 and days_from_phm_to_sunday == 6: |
| 48 | return datetime(year, 4, 19, tzinfo=UTC) |
| 49 | elif days_to_add == 28 and days_from_phm_to_sunday == 6: |
| 50 | return datetime(year, 4, 18, tzinfo=UTC) |
| 51 | else: |
| 52 | return datetime(year, 3, 22, tzinfo=UTC) + timedelta( |
| 53 | days=int(days_to_add + days_from_phm_to_sunday) |
| 54 | ) |
| 55 | |
| 56 | |
| 57 | if __name__ == "__main__": |