On 2017-01-31 02:19 PM, Warner Losh wrote:
On Tue, Jan 31, 2017 at 12:08 PM, Steve Allen <s...@ucolick.org> wrote:
On Tue 2017-01-31T13:58:15 -0500, Brooks Harris hath writ:
Ah, so who's right?
I prefer to think of a leap second as being truly intercalary.
It is saying to atomic clock "It's not tomorrow yet, wait a second."
It is between one calendar day of UTC and the next calendar day of UTC.
It belongs to neither of them. The tag 2016-12-31T23:59:60 is merely
a way of indicating which two days it is between.
It is unfortunate that nobody thought this stuff through in 1969 when
the decision was made to implement the leap second, and no matter how
it is expressed, encoded, and calculated it will be a special case.
Philosophically you may be right.
It doesn't seem philosophical to me. Its obviously a special case, a
special case of interoperablity decreed by the IERS.
Mathematically, however, I don't think that makes much sense. :60 is
an irregular radix. It's clearly added to the prior day, just like Feb
29th is part of February.
Yes.
Also, doing the long-hand math on the
irregular radix, it also makes sense to have it be part of the prior
day
It is, right? And that's what Rec 460 clearly says.
and to increment the offset at the start of the leap second.
Not necessarily.
What part of Gregorian YMDhms or DST makes any "sense"? They are
unavoidable conventions, wacky unavoidable conventions with mixed radix
components and deceptive algorithmic rules. UTC with Leap Seconds alters
those conventions slightly. Why would we expect it to "make sense"?
I think Bulletin C says the TAI-UTC value increments at the start of the
day:
" UTC TIME STEP on the 1st of January 2017" and
"from 2017 January 1, 0h UTC, until further notice : UTC-TAI = - 37s ".
It doesn't say "the second before 2017 January 1".
-Brooks
Warner
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