Re: interoperability

2006-01-09 Thread Clive D.W. Feather
Rob Seaman said: The question of delivering wall clock time is a trivial elaboration on first delivering common international business time. (I'm trying on different terminology than civil time until I hit one that sticks.) I don't accept that the concept exists. The international business

Re: The opportunity of leap seconds

2006-01-09 Thread Peter Bunclark
On Sun, 8 Jan 2006, Tom Van Baak wrote: Peter, So where do these modern telescope get UT1? Do you or The last time I was involved personally was during my time as a support astronomer at the Isaac Newton Group on La Palma in the early nineties. We had a radio receiver which required upcoming

Re: interoperability

2006-01-09 Thread Steve Allen
On Mon 2006-01-09T08:20:40 +0100, Poul-Henning Kamp hath writ: beginning (SI seconds are constant length). Yes, SI seconds are constant length, but the ghost of my general relativity teacher prompts me to assert that my SI seconds are not equal to your SI seconds because we are in different

Re: interoperability

2006-01-09 Thread Clive D.W. Feather
Rob Seaman said: I have heard no response to my discussion of techniques for achieving synchronization - of the difference between naive fall back hours and 25 hour days. But how in practice is it envisaged that a scheme for migrating time zones versus TAI would work, precisely? In the short

Re: interoperability

2006-01-09 Thread Poul-Henning Kamp
In message [EMAIL PROTECTED], Steve Allen writes: On Mon 2006-01-09T08:20:40 +0100, Poul-Henning Kamp hath writ: beginning (SI seconds are constant length). Yes, SI seconds are constant length, but the ghost of my general relativity teacher prompts me to assert that my SI seconds are not equal

Re: The real problem with leap seconds

2006-01-09 Thread Poul-Henning Kamp
In message [EMAIL PROTECTED], Clive D.W. Feather writes: The real problem is not the 23:59:60, it's *predicting* when they happen. I agree, the short prediction horizon is the major problem. But 23:59:60 _is_ a problem too. I don't think anybody dare even think about redefining POSIX time_t

Re: The real problem with leap seconds

2006-01-09 Thread Clive D.W. Feather
I wrote: Right now, the DTAI(TAI) function is the sum of a set of Kroneker delta functions. Thanks to David for quietly pointing out that I meant Heaviside step functions, not Kroneker delta functions. -- Clive D.W. Feather | Work: [EMAIL PROTECTED] | Tel:+44 20 8495 6138 Internet

Re: The real problem with leap seconds

2006-01-09 Thread Poul-Henning Kamp
In message [EMAIL PROTECTED], Peter Bunclark writes: On Mon, 9 Jan 2006, Poul-Henning Kamp wrote: I don't think anybody dare even think about redefining POSIX time_t I wish people would stop making positive assertions about what other people are bound to think. What you mean in is, YOU are

Re: The real problem with leap seconds

2006-01-09 Thread Clive D.W. Feather
Poul-Henning Kamp said: So the standards crew, POSIX, LSB or whoever would have to come up with a new data type for holding timestamps, We already have one: struct tm. There is no doubt that from a humanistic point of view it would be better to educate all the programmers, but considering

Re: interoperability

2006-01-09 Thread Rob Seaman
On Jan 9, 2006, at 12:06 AM, Poul-Henning Kamp wrote: You yourself defined stage one as TAI with some constant offset yourself, you can't change definition in the middle of the discussion. I was attempting to describe your position. In point of fact, I agree with Tom Van Baak: You cannot

Re: interoperability

2006-01-09 Thread Rob Seaman
On Jan 9, 2006, at 12:23 AM, John Cowan wrote: This is like the day is light and night is dark statement: there is, at any given location, one and only one sunrise per (solar) day, no matter what clocks say. Communication prospers when people's clear meaning is not subjugated to petty

Re: interoperability

2006-01-09 Thread Rob Seaman
On Jan 9, 2006, at 1:01 AM, Clive D.W. Feather wrote: We go through such discontinuities twice a year in most years. Only the uninteresting daylight saving jumps. UTC remains without discontinuities above the level of a leap second. If UTC weren't equivalent to what I call civil time, the

Re: interoperability

2006-01-09 Thread Rob Seaman
On Jan 9, 2006, at 1:22 AM, Clive D.W. Feather wrote: At some point, probably around the time that we're seeing an hourly shift every year, people are going to have to divorce second from day, or at least re-negotiate the terms of engagement. By what magic do we believe the issues involved

Re: interoperability

2006-01-09 Thread John Cowan
Rob Seaman scripsit: This is like the day is light and night is dark statement: there is, at any given location, one and only one sunrise per (solar) day, no matter what clocks say. Communication prospers when people's clear meaning is not subjugated to petty grammarians. My point was that

Re: The real problem with leap seconds

2006-01-09 Thread Markus Kuhn
M. Warner Losh wrote on 2006-01-09 16:57 UTC: There's been many many many people that have tried to fix POSIX time_t. One person's fix is another person's recipe for disaster ... The POSIX definition of time_t is not quite as broken as some individuals would like you to believe. It actually

Re: The real problem with leap seconds

2006-01-09 Thread Warner Losh
From: Markus Kuhn [EMAIL PROTECTED] Subject: Re: [LEAPSECS] The real problem with leap seconds Date: Mon, 09 Jan 2006 19:12:05 + M. Warner Losh wrote on 2006-01-09 16:57 UTC: There's been many many many people that have tried to fix POSIX time_t. One person's fix is another person's

Re: The real problem with leap seconds

2006-01-09 Thread Poul-Henning Kamp
In message [EMAIL PROTECTED], Markus Kuhn writes: and you still cannot even get it reliably from your average local NTP server. This is a circular argument: The reason NTP doesn't provide it is that time_t needs UTC. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 [EMAIL PROTECTED]

Re: The real problem with leap seconds

2006-01-09 Thread Tim Shepard
and you still cannot even get it [TAI] reliably from your average local NTP server. This is a circular argument: The reason NTP doesn't provide it is that time_t needs UTC. No, I asked David Mills about 15 or so years ago why NTP distributes UTC and not TAI (me thinking and suggesting that

Re: The real problem with leap seconds

2006-01-09 Thread Mark Calabretta
On Mon 2006/01/09 10:01:27 -, Clive D.W. Feather wrote in a message to: LEAPSECS@ROM.USNO.NAVY.MIL I've just read through the email that has accumulated on this list since before xmas - impressive volume! Why not devote a fraction of that time and energy to producing a formal position paper.

Re: The real problem with leap seconds

2006-01-09 Thread Mark Calabretta
On Mon 2006/01/09 10:38:54 -, Peter Bunclark wrote in a message to: LEAPSECS@ROM.USNO.NAVY.MIL I't be interesting to do an FFT on this list, and see if some of the contributers actually ever sleep, or do any other work... I had the same thought - the moreso when I reflect on the nil response