On Wed, Feb 24, 2010 at 1:12 AM, Steve Allen <sla29...@gmail.com> wrote:
> Hello Mark Reed and Larry Wall
Brought back to the whole list; Larry and I were hardly the only two
folks involved in this discussion.
> On Feb 23, 6:35 am, markjr...@gmail.com ("Mark J. Reed") wrote:
>> OK, this seems to be a point of confusion. TAI *is defined in terms
>> of the Gregorian calendar*.
>
> Are you sure? The Circular T gives dates as counts of atomic days in
> MJD. > Have you asked the BIPM?
The Circular T gives MJD, but most references give ISO date/time
strings. It doesn't change my point, because it's still given in
days, not seconds. In particular, an integral MJD corresponds to
midnight, and atomic midnight currently happens 34 seconds before
civil midnight.
> No, TAI does not tick. There is no clock anywhere that give TAI.
> TAI is not known until next month when the BIPM says what TAI was.
Fair enough: official TAI is only known exactly after the fact. But
it can still be said to tick at a certain rate, even if you only know
that rate later. My point was only that all the atomic timescales,
including UTC, tick at that same rate, because they are defined in
terms of TAI. And of course, the whole point of atomic clocks is that
they do a very good job of keeping time in between those monthly
reports.
> And thus the perl 6 spec is devising a new time scale which not TAI, just as
> POSIX is not UTC.
Comparing this to the POSIX situation is a rather harsh overstatement,
I feel. But if you'll examine Larry's latest revision to S02, you'll
note that it no longer claims that Instants give TAI; the only mention
of TAI is in reference to its initialization point of
1958-01-01T00:00:00 (or MJD 36204.0, if you prefer) as one of the
predefined epochs.
--
Mark J. Reed <markjr...@gmail.com>
