Re: Use Vim to compute the date of Easter

On Sat, May 2, 2020 at 8:05 PM 'Chris Willis' via vim_use
<vim_use@googlegroups.com> wrote:
> Known limitation: the input must be an integer (or a String or Float
> which will be converted to an Integer) > 1582, and only _Gregorian_
> Easter dates are produced. If you want to compute Julian (Orthodox)
> Easter, or Pesach, or the Chinese New Year, or something else, go
> ahead and write them: they are not the purpose of this script, which
> "does one thing, does it predictably, and doesn't try to do a lot of
> other things on the side".
>
> Have fun!
> Tony.
>
> Hi Tony
>
> I'm not sure where you're based. You realise, I expect, that England (and I
> think the USA) didn't change to the Gregorian calendar until 1752. I'm not
> sure whether all western Europe celebrated Easter on the same day despite
> the different dates in the interim. It wd appear not.
>
> regards - Chris

Well, no one celebrated Easter according to the Gregorian computus
before the Gregorian calendar reform (October 1582); someone (Spain,
Portugal, the Papal states, much of Italy, France (as it existed at
the time), the united Kingdom of Poland and Grand-Duchy of Lithuania,
…) did as soon as 1583; so it doesn't make sense to use that formula
before 1583 but from that date it does. Catholic, Protestant and
Anglican countries and churches adopted the Gregorian calendar at
various dates in October 1582 or later; nowadays they all use it. OTOH
Orthodox churches usually still use the Julian calendar even though
the civil administration in the same countries uses Gregorian, so
their Easter may or may not be on the same day, sometimes it's one
week apart, sometimes it's one lunar month apart, so don't use this
little program for that, or to know when Easter happened in England in
1600 (if you ask for 1600 you'll get an answer but it will be the date
for, among others, Spain and Portugal).

If you (or anyone) want to know when your country adopted the
Gregorian calendar, see
https://en.wikipedia.org/wiki/Gregorian_calendar#Adoption_of_the_Gregorian_Calendar
— Austria is not mentioned but from the note at "Yugoslavia" you can
deduce that Austria-Hungary switched over in 1583, shortly before the
"Kingdom of Bohemia" (which approximately corresponds to present-day
Czech Republic). Present-day Netherlands are "Protestant Low
Countries" of course, except that IIRC North Brabant and Limburg were
Catholic and under Spanish rule (for Dutch Flanders I'm not sure); and
beware that Strasbourg changed at a different date from the rest of
Alsace and that neither was part of "France" in 1582. For Lorraine see
the note in the rightmost column of the table at
https://en.wikipedia.org/wiki/Gregorian_calendar#Beginning_of_the_year

P.S. I live in Brussels, Belgium, which was then part of "Catholic Low
Countries" and under Spanish rule.

P.P.S. Gauss invented as a child the formula on which this method is a
minor improvement because he wanted to know his birthday: his mother
only remembered that is was "on a Wednesday, one week before Ascension
day". Germany had made the changeover more than 70 years before he was
born, so he used Gregorian computus.


Best regards,
Tony.

--
--
You received this message from the "vim_use" maillist.
Do not top-post! Type your reply below the text you are replying to.
For more information, visit http://www.vim.org/maillist.php

---
You received this message because you are subscribed to the Google Groups "vim_use" group.
To unsubscribe from this group and stop receiving emails from it, send an email to vim_use+unsubscribe@googlegroups.com.
To view this discussion on the web visit https://groups.google.com/d/msgid/vim_use/CAJkCKXuQmPMCQ36wyQLgrL0JVjYMfL23%3D%2BSAawW_sQa69Se1Kg%40mail.gmail.com.