Re: [Gretl-devel] calendar (was Re: Gretl-devel Digest, Vol 121, Issue 20)
On Thu, 16 Feb 2017, Allin Cottrell wrote:
On Thu, 16 Feb 2017, Ignacio Diaz-Emparanza wrote:
> OK. I understand. Good to know that gretl is doing well.
> It is interesting that in this url the calendar for Spain in 1700 is
> different from the US calendar.
Thanks for digging into this, Ignacio. I think we have to switch to
the proleptic Gregorian calendar. This means that our dates will not
match the historical calendar from before the introduction of the
Gregorian calendar (1752 in England; 1582 in Spain, Portugal, France
and Italy; and at various other times for other countries).
There's no way we can match all historical calendars. Up till now
we've matched the English calendar (following "cal") with regard to
leap years, but I'm afraid not with full consistency. It's extremely
difficult to achieve consistency without prolepsis: in the English
case, we'd have to deal with the fact that September 1752 had only
19 days (they skipped from Wednesday the second to Thursday the
14th)! For econometric purposes let's go with a calendar that has
consecutive dates (as I gather database software does).
At some point we could maybe add a function that translates from
Gregorian to Julian dates and vice versa, in case that's of any
interest -- I wonder how many econometricians work with archival
daily data from Julian-calendar days?
Allin