Day of week routine

[Felix Lee]

In article <322 at xdos.UUCP>,
   doug at xdos.UUCP (Doug Merritt) writes:
>Try this:
>	((year * 1.25) + (day-of-the-year) + constant) modulo 7

Using a strict interpretation of (day-of-the-year), you should use
(year + (year-1)/4) instead of (year * 1.25).

For the Gregorian calendar, try this instead:
	year + (year-1)/4 - (year-1)/100 + (year-1)/400.

Note that not all countries adopted the Gregorian calendar at the
same time.  (Japan was quite late, something like 19th century?)
--
Felix Lee	flee at shire.cs.psu.edu	*!psuvax1!shire!flee