[LEAPSECS] php breaks if UTC has no leap seconds?

Richard B. Langley lang at unb.ca
Fri Dec 10 11:18:58 EST 2010

USNO predicts UT1-UTC. In Bulletin A
<http://maia.usno.navy.mil/ser7/ser7.dat>, they predict daily values
for a year in advance but only provide an error estimate up to 40 days
in advance. Elsewhere <http://maia.usno.navy.mil/ser7/deltat.preds>,
longer-term predictions are given; supposedly updated annually.

-- Richard Langley

Quoting Warner Losh <imp at bsdimp.com>:

> On 12/09/2010 17:35, Rob Seaman wrote:

>> On Dec 9, 2010, at 3:53 PM, Steve Allen wrote:


>>> This is the first example I've come across where a widely used API

>>> will break if UTC does not continue to have leap seconds.

>> Has anyone even considered a Y2K style inventory?


>> Absence of evidence is not...oh, what's the point?

> Keep in mind that while a code change would required to fetch DUT1

> from the internet or other source, the API could continue to

> function, but with an increased uncertainty as the date is farther

> into the future. If this is an important number to know, I'm sure

> someone will publish a model that tries to approximate dUT1 and

> gives an uncertainty range that presumably expands the further into

> the future we go.


> You're correct about the question: How many of these interfaces are

> there, and what is the implication for increasing the error in the

> present calculation from 1s? For php, I doubt anybody would care

> for the cases likely to be in error... For other things, likely

> they care more.


> Warner

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Richard B. Langley E-mail: lang at unb.ca
Geodetic Research Laboratory Web: http://www.unb.ca/GGE/
Dept. of Geodesy and Geomatics Engineering Phone: +1 506 453-5142
University of New Brunswick Fax: +1 506 453-4943
Fredericton, N.B., Canada E3B 5A3
Fredericton? Where's that? See: http://www.city.fredericton.nb.ca/

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