def fromordinal_alt(cls, ordinal):
"""Return the date corresponding to ordinal date .
Alternative calculation."""
y = cls.to_year(cls.EPOCH - 1 + ordinal + 306)
prior_days = ordinal - GregorianDate(y - 1, MonthOfYear.MARCH, 1).toordinal()
month = amod(quotient(5 * prior_days + 2, 153) + 3, 12)
year = y - quotient(month + 9, 12)
day = ordinal - GregorianDate(year, month, 1).toordinal() + 1
return GregorianDate(year, month, day)
def toordinal(self):
"""Return the serial date equivalent."""
return ((self.EPOCH - 1) +
(365 * (self.year -1)) +
quotient(self.year - 1, 4) -
quotient(self.year - 1, 100) +
quotient(self.year - 1, 400) +
quotient((367 * self.month) - 362, 12) +
(0 if self.month <= 2 else (-1 if self.is_leap_year(self.year) else -2)) + self.day)
def alt_orthodox_easter(year):
"""Return ordinal date of Orthodox Easter in Gregorian year g_year.
Alternative calculation."""
paschal_moon = (354 * year +
30 * quotient((7 * year) + 8, 19) +
quotient(year, 4) -
quotient(year, 19) -
273 +
GregorianDate.EPOCH)
return after_weekday(paschal_moon, DayOfWeek.SUNDAY)
def to_year_alt(cls, ordinal):
"""Return the year corresponding to the ordinal date.
Alternative calculation."""
approx = quotient(ordinal - cls.EPOCH + 2, Fraction(146097, 400))
start = (cls.EPOCH +
(365 * approx) +
quotient(approx, 4) +
-quotient(approx, 100) +
quotient(approx, 400))
return approx if ordinal < start else approx + 1
def fromordinal_arithmetic(cls, ordinal):
"""Return French Revolutionary date [year, month, day] of ordinal
ordinal, ordinal."""
approx = quotient(ordinal - cls.EPOCH + 2, 1460969/4000) + 1
year = ((approx - 1)
if (ordinal < FrenchDate(approx, 1, 1).toordinal_arithmetic())
else approx)
month = 1 + quotient(ordinal - FrenchDate(year, 1, 1).toordinal_arithmetic(), 30)
day = ordinal - FrenchDate(year, month, 1).toordinal_arithmetic() + 1
return FrenchDate(year, month, day)
def toordinal_arithmetic(self):
"""Return ordinal date of French Revolutionary date, f_date."""
return (self.EPOCH - 1 +
365 * (self.year - 1) +
quotient(self.year - 1, 4) -
quotient(self.year - 1, 100) +
quotient(self.year - 1, 400) -
quotient(self.year - 1, 4000) +
30 * (self.month - 1) +
self.day)
def to_year(cls, ordinal):
"""Return the year corresponding to the ordinal date."""
d0 = ordinal - cls.EPOCH
n400 = int(math.floor(d0 / 146097))
d1 = d0 % 146097
n100 = quotient(d1, 36524)
d2 = d1 % 36524
n4 = quotient(d2, 1461)
d3 = d2 % 1461
n1 = quotient(d3, 365)
year = (400 * n400) + (100 * n100) + (4 * n4) + n1
return year if n100 == 4 or n1 == 4 else year + 1
def fromordinal(cls, ordinal):
"""Return French Revolutionary date of ordinal date, 'ordinal'."""
new_year = cls.new_year_on_or_before(ordinal)
year = iround((new_year - cls.EPOCH) / MEAN_TROPICAL_YEAR) + 1
month = quotient(ordinal - new_year, 30) + 1
day = ((ordinal - new_year) % 30) + 1
return FrenchDate(year, month, day)
def fromordinal(cls, ordinal):
"""Return the ordinal_date corresponding to ordinal date."""
year = cls.to_year(ordinal)
prior_days = ordinal - cls.new_year(year)
correction = 0 if ordinal < GregorianDate(year, MonthOfYear.MARCH, 1).toordinal() else (1 if cls.is_leap_year(year) else 2)
month = quotient((12 * (prior_days + correction)) + 373, 367)
day = 1 + (ordinal - GregorianDate(year, month, 1).toordinal())
return GregorianDate(year, month, day)
def easter(cls, year):
"""Return ordinal date of Easter in Gregorian year 'year'."""
century = quotient(year, 100) + 1
shifted_epact = ((14 + 11 * (year % 19) - int(math.floor((3 * century) / 4)) + int(math.floor((5 + (8 * century)) / 25)) ) % 30)
adjusted_epact = shifted_epact + 1 if shifted_epact == 0 or (shifted_epact == 1 and 10 < year % 19) else shifted_epact
apr19 = GregorianDate(year, MonthOfYear.APRIL, 19)
paschal_moon = apr19.toordinal() - adjusted_epact
return after_weekday(paschal_moon, DayOfWeek.SUNDAY)