method
valid_ordinal?
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valid_ordinal?(y, d, sg=ITALY)
public
Do the year y and day-of-year d make a valid Ordinal Date? Returns the corresponding Julian Day Number if they do, or nil if they don’t.
d can be a negative number, in which case it counts backwards from the end of the year (-1 being the last day of the year). No year wraparound is performed, however, so valid values of d are -365 .. -1, 1 .. 365 on a non-leap-year, -366 .. -1, 1 .. 366 on a leap year. A date falling in the period skipped in the Day of Calendar Reform adjustment is not valid.
sg specifies the Day of Calendar Reform.