On Mon, Feb 6, 2017 at 10:58 AM, Zefram <[email protected]> wrote: > Warner Losh wrote: >>Saying that the two numbers are the same is improper. Or rather, it >>depends on which time scale you are looking at them in if they are >>improper. > > The numbers are not on any time scale. The numbers are derived from > the time values, but are a different thing.
They are second labels which have different rules for TAI and UTC. >>However, if you look at the two times in UTC land and compute a delta >>in UTA land, then you find the interval between N:23:59:60 and >>N+1:00:00:00 you wind up with 1 second. That leads to the conclusion >>that the difference starts at the beginning of the leap second. > > It does not lead to that conclusion in the general case. (It does for > the specific case of TAI-UTC changing from 0 s to 1 s.) This is one of > the options for handling TAI-UTC that I examined a few messages ago, > and it leads to the conclusion that if TAI-UTC is initially positive > then it increases some seconds *before* the leap second. Actually it doesn't. I couldn't follow the logic on that argument at all, so I didn't reply. At worst if you misapplied my method, you'd get an off by one error. > I'd examined it > because it appeared to me that, by consistently using the irregular radix > for subtraction, it was applying the principle that you were claiming to > apply, though it leads to a different conclusion from the one you reached. > (You responded that this was not your system.) Yea, I've read through your message a couple of times and still don't understand how you got to where you did. > I'd still like to see from you a worked example of TAI-UTC for a time a > few seconds before a positive leap second, where TAI has already ticked > over into the following day, to compare against an equivalent example > for a time inside the same positive leap second. You've done a worked > example inside a leap second, but not one in the preceding seconds. > I want to see how you get a different result for 00:00:35-23:59:59 from > that which you get for 00:00:36-23:59:60. Sure. I still owe you that, and plan on giving you that. I'm a bit crunched for time today since I've been working to get a release done by noon today for the past week (for a problem that exploded into my lap just after this thread started). >>can't normalize N:23:59:60 to N+1:00:00:00 because in UTC they are two >>different second labels. > > They certainly are different second labels, and in UTC they even > label different seconds. That's not in dispute. I did not normalise > one of them to the other. The equivalence between them is only that > certain relevant functions of UTC time labels, specifically MJD and its > equivalents, yield the same value for both of these. It is via those > functions that TAI-UTC is tacitly defined. When you convert to MJD, it appears you are assuming each day has 86400 seconds, which is why two seconds map to the same value. Warner _______________________________________________ LEAPSECS mailing list [email protected] https://pairlist6.pair.net/mailman/listinfo/leapsecs
