Re: Date and time on Cindu: yearly update
From: | Mark J. Reed <markjreed@...> |
Date: | Monday, May 19, 2008, 4:18 |
On Sun, May 18, 2008 at 11:50 PM, ROGER MILLS <rfmilly@...> wrote:
> >You have a purely arithmetic rule about *when* a leap year occurs
>> (years 4, 10, and 17 of a 19-year cycle),
>
> I don't think so: according to my calc. 700 - 706 - 713 - 719 - 725 - 732 -
> 738 etc. were leap years, so it goes 6-7-6.
RIght, those are the intervals between leap years: 6 years, then 7
years, then 6 years. That means that you have a pattern of leap years
within common years that repeats every 6+7+6 = 19 years; that's the
"19-year cycle" I mentioned.
When I said "years 4, 10, and 17", I didn't mean "4 years, then 10
years, then 17 years"; I meant, "year 4, then skip 6 years to year 10,
then skip 7 years to year 17". After that, you skip 6 years again,
but the leap-year cycle starts over at 1 after year 19. So from 17 to
18 (1 year) to 19 (2 years) to year 1 of the next cycle (3 years) to
year 2 (4 years) to year 3 (5 years) to year 4 (6 years): 6 years
brings you back to year 4 again, and the pattern of 4, 10, 17 repeats
over and over again.
Those numbers were based on this bit from
http://cinduworld.tripod.com/cindustats.htm: "the last leap year was
751, the next one will be 758." However, if that's correct, then your
list above is not - if 700, 706, and 713 are leap years, then 758
would not be one; 757 and 763 would be:
0 | +6 +7 +6
700 | 706 713 719
719 | 725 732 738
738 | 744 751 757
757 | 763 770 776
So which list do you want to be correct?
> I like that [leap day changing every time] better than having it be a fixed day.
I agree with you there. Complex is fun. :)
> (NB I am not skilled at this sort of thing!!!)
That puts you in good company. JRRT said exactly the same thing in
his description of the Shire calendar. :)
> I'm still digesting your long previous post..........
I apologize for the length. Not trying to confuse anyone. Just
trying to get enough detail to allow me to make a tool for you...
--
Mark J. Reed <markjreed@...>
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