On Feb 22, 2009, at 12:39 AM, Brandon S. Allbery KF8NH wrote:
On 2009 Feb 20, at 14:36, Chris Dolan wrote:
UTC: TAI with an offset, as corrected for the actual revolution
of the
Earth: usually 60 seconds in a minute, but occasionally 59 or
61. 60
minutes in every hour (so 3599, 3600, or 3601 seconds), 24 hours in
every day (86399, 86400, or 86401 seconds).
Yes, just as I said: a constant offset between each of the proposed
Read again; a leap second was added at the end of last year, that's
not exactly "constant".
You missed the trivial point I was trying to make: the number of
seconds between January 1, 1970 UTC (aka time_t epoch) and January 1,
2000 TAI *epochs* is a constant. I did not claim that the time
systems differed by a constant. An epoch is an instant in time from
which other times are measured, so you can measure UTC time flowing
from a TAI epoch and vice versa.
Astronomers do this all the time to avoid the complexity that the
Earth's rotation precesses, so the time to orbit the Sun once it not
exactly the same as a solar year. Astrometric coordinates are thus
claimed relative to an epoch, say B1950 or J2000, and can be easily
transformed between epochs.
Nevertheless, Larry has closed the issue declaring that Perl 6 will
use TAI, and I'm cool with that. With just 30-odd lossy exceptions
in the last 40 years, we can translate between TAI and time_t as
needed. When the OSes catch up and stop using time_t, it will be a
glorious day.
... unless we decide to use Stardates instead. Floating point time
would be cooler. :-)
Chris
