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roundtrip for proleptic_gregorian calendar wrong for reference dates before Julian/Gregorian transition #189
Description
import cftime as cf
from cftime import DatetimeProlepticGregorian as datetime
dt1 = datetime(2020, 4, 24, 16, 15, 10)
print(dt1)
units='days since -4713-01-01 12:00'
cal='proleptic_gregorian'
print(cf.num2date(cf.date2num(dt1, units, cal), units, cal))
2020-04-24 16:15:10
2020-03-19 16:15:10For this example, it's off by 38 days.
Correct result is obtained if reference date year changed to 1583.
Activity
jswhit commentedon Jul 17, 2020
Actually, it works for reference date years back to -100. Suspect it has something to do with the calculation of leap years for negative years.
It's a bug in _is_leap - fix is included in PR #188
jswhit commentedon Jul 18, 2020
closed by PR #188