Date: Sun, 22 Feb 1998 15:39:10 -0700 (MST)
Message-Id: <199802222239.PAA25126@kewlaid.highfiber.com>
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To: opendos AT delorie DOT com
From: raster AT highfiber DOT com (Charles Dye)
Subject: Re: Y2K fix
Precedence: bulk

ark AT mos DOT ru (Arkady V.Belousov) writes:

>21-Feb-98 18:12 raster AT highfiber DOT com (Charles Dye) wrote to
opendos AT delorie DOT com:
>
> > 2000 will be a leap year.  Enjoy it -- a leap day in a year ending in 00
> > is a rare occurrence in the Gregorian calendar, happening only once every
> > four hundred years.  Such a leap day will always fall on a Tuesday (left
> > as an exercise.)
>
>     O! How fine! You right: (400*365+100-4+1) % 7 == 0.

Darn ...  what they said about Soviet math education might be true after all.
Yes, it is a lovely little coincidence.

> > (which we use) like the much simpler Julian calendar.  Within the range
> > Microsoft chose, you can determine whether a year is leap simply by testing
> > the lowest two bits.
>
>     Hm. You right - y%4==y&3. Why I not see this before?

Then you'll be delighted to hear that it works whether you use "people years"
1980-2099, or "DOS years" 0-119 (as stored in directory entries.)  See what I
mean about picking a clever range?

> > A good all-around guide to the Julian, Gregorian, and even messier systems:
> > ftp.simtel.net/pub/simtelnet/msdos/info/calfaq.zip
>
>     I check this. :)

Do that.  I'm curious -- the author claims that the Eastern Orthodox church
is *still* using the Julian calendar to calculate feasts and holidays and
such.  Would you happen to know anything about that?

raster AT highfiber DOT com