Re: Can I get the Day of the week?

Hi Simon,

Thanks for the info! When you say 0001-01-01 was a Sunday, does that take
into consideration any of the compensatory changes (e.g. 1582 or 1752) that
you mentioned? I seem to recall Pope Gregory dropping 9 days or so in 1582,
which would I would think would make a difference in the day of the week
before and after the dropped dates.

Regards,
Peter Dow
Dow Software Services, Inc.
909 425-0194 voice
909 425-0196 fax

----- Original Message -----
From: "Simon Coulter" <shc@flybynight.com.au>
To: <RPG400-L@midrange.com>
Sent: Wednesday, May 16, 2001 5:45 AM
Subject: Re: Can I get the Day of the week?


> S
> Hello  Peter,
>
> You wrote:
> >Just for fun, how about using a BIF? I have no idea if it's faster; then
> >again with today's processors, speed is not always a big issue. But it's
> >shorter. And by using 0001-01-01 as the base, I don't have to worry about
> >negatives. However, it does return Monday as 1 instead of the more
> >traditional Sunday, and I have no idea if it's correcting for dates prior
to
> >1533 or whenever it was that the calendar was adjusted...
>
> The system uses a Proleptic Gregorian calendar for its date calculations.
That
> means it applies Gregorian rules to dates that are really Julian.  It
doesn't
> compensate for the rules that were in force prior to 4th October 1582
(when
> the Gregorian calendar came in force -- at least in most Catholic
countries) or
> prior to 2nd September 1752 for Britain or its colonies (including the USA
at
> the time).
>
> The system uses the Scaliger algorithm to calculate dates which in itself
has an
> interesting bug.  Initialise a DATE field in RPG IV to 0300-03-01 and use
debug
> to see what date actually gets stored.
>
> Sunday is the conventional start of the week in Western countries, but the
ISO
> standard pegs the start of the week as Monday.  And 0001-01-01 was
actually a
> Sunday and 9999-12-31 will be a Friday (assumming there is no compensation
for
> the leap year drift that will be apparent by 4000).
>
> Watch this space for a set of date routines that does handle historical
dates
> correctly ....
>
> P.S. %REM (and its litter mate %DIV) came in at 440 for those of you
> contemplating using it.
>
> Regards,
> Simon Coulter.
>
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