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Re: times, dates, images, and S-W
- To: email@example.com
- Subject: Re: times, dates, images, and S-W
- From: cbmvax!uunet!math.ucla.edu!jimc
- Date: Thu, 13 Sep 90 11:29:43 -0700
- Cc: "Arthur W. Protin Jr." (GC-ACCURATE) <protin@PICA.ARMY.MIL>
- In-reply-to: Your message of "Mon, 06 Aug 90 16:59:59 EDT." <9008061659.aa08340@COR4.PICA.ARMY.MIL>
- Resent-date: Fri, 19 Jul 91 16:26:22 EDT
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- Resent-message-id: <9107192031.AA16839@relay1.UU.NET> 13 Sep 90 14:31 EDT
- Resent-to: John Cowan <firstname.lastname@example.org>
I also am a little slow getting caught up. On Arthur Protin's use of
yymmdd date format, there is in fact an ISO standard prescribing this
order. I don't have the number right handy but it's in the library and
I could re-check features if anyone's interested. Here's my
recollection from several years ago:
The date consists of fields of digits separated by anything else. The
standard wasn't exactly clear what was or was not allowed as
separators. The first number is a year. I don't remember if there was
a prescription for what to do with two-digit years. Next is a month
and last is a day. Time-of-day was not addressed. The Gregorian
calendar is (tacitly?) assumed.
In -gua!spi I have a "vector" construct in which X2, X3, ... (as many
as needed) are expressions and X1 is an ordered list with these
members. This fits right in with dates; X1 (one of these vectors) is
the date of event X2 starting with unit X3 (default years) with
calendar style X4. A transitive compound with "hours" gives you
I wonder if time-of-day or date should have the preference? In a
language with a very mechanistic style you must choose one; you can't
rely on semantics to suggest which is meant, but you don't want
separate primitive words for both concepts.
> Now if you want to redefine all our clocks to fill a day with 100,000
> units approximately equal to 0.864 seconds ...
In the late 50's, Donald Knuth (yes, THE Donald Knuth) published a piece
entitled "The Potrzebie System of Units" in Mad Magazine, in which he
did just that. If I remember right, 1E-5 * day was called a "martin".
The article helped me greatly to understand unit systems and their
metrological considerations -- much more than the explanations I was
getting in school.