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Re: hours since 1-1-1 [message #44980 is a reply to message #44859]

Wed, 27 July 2005 14:32

Michael Wallace
Messages: 409
Registered: December 2003

Senior Member

>> Anyway, IDL has the JULDAY function, which calculates time in Julian
>> days, ie time since 12:00 hours on 1 Jan 4713BC. (OK, I withdraw my
>> comment about 1 Jan 0001 being the silliest ever date-time origin.)
>
>
> The epoch for the Julian Day system may seem silly, but it was
> originally designed for use with ancient historical data.

Actually, I love Julian Day for one simple reason. No matter what data
I'm looking at, I never have to use negative numbers to represent the
date. You wouldn't believe what kind of hilarity ensues when you try to
work with dates as negative numbers.

I give the Silliest Epoch Award to Macintosh for their selection Jan 1,
1904 as their base epoch for MacOS. Apparently, they were originally
going to use Jan 1, 1900 which seems to be a logical choice, but then
someone remembered that 1900 was not a leap year. Every four years
after 1900 there would be a leap year until 2100. By not including
1900, they then didn't have to bother with coding those extra pesky leap
year rules that everyone always forgets. And to make things even
better, it was easiest for them to start their epoch on a leap year and
so 1904 became their epoch. Hopefully, no one will be running MacOS in
2100. Besides, the rest of us have to make it past 2038 first. :-)

-Mike

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[Message index]

		Re: hours since 1-1-1 By: James Kuyper on Tue, 26 July 2005 21:40
		Re: hours since 1-1-1 By: Mark Hadfield on Tue, 26 July 2005 20:00
		Re: hours since 1-1-1 By: Michael Wallace on Wed, 27 July 2005 14:32
		Re: hours since 1-1-1 By: R.Bauer on Thu, 04 August 2005 06:51

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