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Groups > comp.programming > #7182 > unrolled thread
| Started by | "Mr. Man-wai Chang" <toylet.toylet@gmail.com> |
|---|---|
| First post | 2016-12-22 21:43 +0800 |
| Last post | 2017-01-03 20:26 -0500 |
| Articles | 13 on this page of 93 — 33 participants |
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'Leap Second' to Be Added on New Year's Eve This Year "Mr. Man-wai Chang" <toylet.toylet@gmail.com> - 2016-12-22 21:43 +0800
Re: 'Leap Second' to Be Added on New Year's Eve This Year Siri Cruise <chine.bleu@yahoo.com> - 2016-12-22 05:48 -0800
Re: 'Leap Second' to Be Added on New Year's Eve This Year "Mr. Man-wai Chang" <toylet.toylet@gmail.com> - 2016-12-22 22:09 +0800
Re: 'Leap Second' to Be Added on New Year's Eve This Year Krzysztof Mitko <invalid@kmitko.at.list.dot.pl> - 2016-12-24 13:47 +0100
Re: 'Leap Second' to Be Added on New Year's Eve This Year Siri Cruise <chine.bleu@yahoo.com> - 2016-12-24 05:39 -0800
Re: 'Leap Second' to Be Added on New Year's Eve This Year Mark Lloyd <not@mail.invalid> - 2016-12-22 14:31 -0600
Re: 'Leap Second' to Be Added on New Year's Eve This Year Mark Storkamp <mstorkamp@yahoo.com> - 2016-12-23 08:34 -0600
Re: 'Leap Second' to Be Added on New Year's Eve This Year "J-P. Rosen" <rosen@adalog.fr> - 2016-12-23 16:55 +0100
Re: 'Leap Second' to Be Added on New Year's Eve This Year Ken Brody <kenbrody@spamcop.net> - 2016-12-30 11:17 -0500
Re: 'Leap Second' to Be Added on New Year's Eve This Year Gene Wirchenko <genew@telus.net> - 2016-12-30 09:38 -0800
Re: 'Leap Second' to Be Added on New Year's Eve This Year hah <hah@no.email.stupid.invalid> - 2016-12-30 15:59 -0600
Re: 'Leap Second' to Be Added on New Year's Eve This Year Mark Lloyd <not@mail.invalid> - 2016-12-30 15:47 -0600
Re: 'Leap Second' to Be Added on New Year's Eve This Year Ken Blake <Ken@invalid.news.com> - 2016-12-30 15:14 -0700
Re: 'Leap Second' to Be Added on New Year's Eve This Year Kaz Kylheku <221-501-9011@kylheku.com> - 2016-12-30 23:26 +0000
Re: 'Leap Second' to Be Added on New Year's Eve This Year "James R. Kuyper" <jameskuyper@verizon.net> - 2017-01-03 20:46 -0500
Re: 'Leap Second' to Be Added on New Year's Eve This Year Jason <jason_warren@ieee.DELETE.org> - 2016-12-22 17:14 -0500
Re: 'Leap Second' to Be Added on New Year's Eve This Year "Jonathan N. Little" <lws4art@gmail.com> - 2016-12-22 17:40 -0500
Re: 'Leap Second' to Be Added on New Year's Eve This Year Jason <jason_warren@ieee.org> - 2016-12-23 19:57 -0500
Re: 'Leap Second' to Be Added on New Year's Eve This Year Char Jackson <none@none.invalid> - 2016-12-23 21:44 -0600
Re: 'Leap Second' to Be Added on New Year's Eve This Year "James Wilkinson Sword" <imvalid@somewear.com> - 2016-12-31 23:42 +0000
Re: 'Leap Second' to Be Added on New Year's Eve This Year Ken Brody <kenbrody@spamcop.net> - 2016-12-30 11:16 -0500
Re: 'Leap Second' to Be Added on New Year's Eve This Year Mark Lloyd <not@mail.invalid> - 2016-12-30 15:58 -0600
Re: 'Leap Second' to Be Added on New Year's Eve This Year Keith Thompson <kst-u@mib.org> - 2016-12-30 14:37 -0800
Re: 'Leap Second' to Be Added on New Year's Eve This Year Mark Lloyd <not@mail.invalid> - 2016-12-30 19:16 -0600
Re: 'Leap Second' to Be Added on New Year's Eve This Year Keith Thompson <kst-u@mib.org> - 2016-12-30 17:48 -0800
Re: 'Leap Second' to Be Added on New Year's Eve This Year Jorgen Grahn <grahn+nntp@snipabacken.se> - 2016-12-31 10:08 +0000
Re: 'Leap Second' to Be Added on New Year's Eve This Year Mark Lloyd <not@mail.invalid> - 2016-12-31 14:20 -0600
Re: 'Leap Second' to Be Added on New Year's Eve This Year Mark Lloyd <not@mail.invalid> - 2016-12-31 14:34 -0600
Re: 'Leap Second' to Be Added on New Year's Eve This Year Wally W. <ww84wa@aim.com> - 2016-12-31 16:45 -0500
Re: 'Leap Second' to Be Added on New Year's Eve This Year Ken Blake <Ken@invalid.news.com> - 2016-12-31 16:34 -0700
Re: 'Leap Second' to Be Added on New Year's Eve This Year Wally W. <ww84wa@aim.com> - 2016-12-31 20:52 -0500
Re: 'Leap Second' to Be Added on New Year's Eve This Year Richard Heathfield <rjh@cpax.org.uk> - 2017-01-01 12:22 +0000
Re: 'Leap Second' to Be Added on New Year's Eve This Year Mark Lloyd <not@mail.invalid> - 2017-01-01 15:47 -0600
Re: 'Leap Second' to Be Added on New Year's Eve This Year Keith Thompson <kst-u@mib.org> - 2016-12-31 13:59 -0800
Re: 'Leap Second' to Be Added on New Year's Eve This Year Wally W. <ww84wa@aim.com> - 2017-01-01 13:46 -0500
Re: 'Leap Second' to Be Added on New Year's Eve This Year Mark Lloyd <not@mail.invalid> - 2017-01-01 16:12 -0600
Re: 'Leap Second' to Be Added on New Year's Eve This Year Wally W. <ww84wa@aim.com> - 2017-01-01 19:44 -0500
Re: 'Leap Second' to Be Added on New Year's Eve This Year Wally W. <ww84wa@aim.com> - 2017-01-01 22:31 -0500
Re: 'Leap Second' to Be Added on New Year's Eve This Year Ken Blake <Ken@invalid.news.com> - 2017-01-02 11:23 -0700
Re: 'Leap Second' to Be Added on New Year's Eve This Year Mark Lloyd <not@mail.invalid> - 2017-01-02 19:03 -0600
Re: 'Leap Second' to Be Added on New Year's Eve This Year Mark Storkamp <mstorkamp@yahoo.com> - 2017-01-02 13:46 -0600
Re: 'Leap Second' to Be Added on New Year's Eve This Year Wolf K <wolfmac@sympatico.ca> - 2017-01-02 14:55 -0500
Re: 'Leap Second' to Be Added on New Year's Eve This Year Andy Burns <usenet@andyburns.uk> - 2017-01-02 20:00 +0000
Re: 'Leap Second' to Be Added on New Year's Eve This Year Sam E <why.should.this@be.email.invalid> - 2017-01-02 19:07 -0600
Re: 'Leap Second' to Be Added on New Year's Eve This Year Gareth Owen <gwowen@gmail.com> - 2017-01-03 06:45 +0000
Re: 'Leap Second' to Be Added on New Year's Eve This Year Wolf K <wolfmac@sympatico.ca> - 2017-01-03 09:42 -0500
Re: 'Leap Second' to Be Added on New Year's Eve This Year "Cybe R. Wizard" <cybe_r_wizard@WizardsTower.invalid> - 2017-01-03 11:27 -0600
Re: 'Leap Second' to Be Added on New Year's Eve This Year Caver1 <caver1@inthemud.org> - 2017-01-03 14:25 -0500
Re: 'Leap Second' to Be Added on New Year's Eve This Year "James R. Kuyper" <jameskuyper@verizon.net> - 2017-01-03 17:34 -0500
Re: 'Leap Second' to Be Added on New Year's Eve This Year Mark Storkamp <mstorkamp@yahoo.com> - 2017-01-02 14:20 -0600
Re: 'Leap Second' to Be Added on New Year's Eve This Year Wolf K <wolfmac@sympatico.ca> - 2017-01-02 15:36 -0500
Re: 'Leap Second' to Be Added on New Year's Eve This Year "James R. Kuyper" <jameskuyper@verizon.net> - 2017-01-04 12:09 -0500
Re: 'Leap Second' to Be Added on New Year's Eve This Year Wolf K <wolfmac@sympatico.ca> - 2017-01-04 19:12 -0500
Re: 'Leap Second' to Be Added on New Year's Eve This Year Wally W. <ww84wa@aim.com> - 2017-01-02 15:06 -0500
Re: 'Leap Second' to Be Added on New Year's Eve This Year Mark Lloyd <not@mail.invalid> - 2017-01-02 19:10 -0600
Re: 'Leap Second' to Be Added on New Year's Eve This Year Wally W. <ww84wa@aim.com> - 2017-01-02 22:56 -0500
Re: 'Leap Second' to Be Added on New Year's Eve This Year "James R. Kuyper" <jameskuyper@verizon.net> - 2017-01-04 12:34 -0500
Re: 'Leap Second' to Be Added on New Year's Eve This Year Mark Lloyd <not@mail.invalid> - 2017-01-04 15:32 -0600
Re: 'Leap Second' to Be Added on New Year's Eve This Year Keith Thompson <kst-u@mib.org> - 2017-01-04 13:51 -0800
Re: 'Leap Second' to Be Added on New Year's Eve This Year Mark Lloyd <not@mail.invalid> - 2017-01-04 22:37 -0600
Re: 'Leap Second' to Be Added on New Year's Eve This Year "James R. Kuyper" <jameskuyper@verizon.net> - 2017-01-04 17:21 -0500
Re: 'Leap Second' to Be Added on New Year's Eve This Year Gene Wirchenko <genew@telus.net> - 2017-01-05 09:20 -0800
[OT] Meaning and truth (Was Re: 'Leap Second' to Be Added on New Year's Eve This Year) Wolf K <wolfmac@sympatico.ca> - 2017-01-05 13:34 -0500
Re: 'Leap Second' to Be Added on New Year's Eve This Year Caver1 <caver1@inthemud.org> - 2017-01-07 17:20 -0500
Re: 'Leap Second' to Be Added on New Year's Eve This Year Kaz Kylheku <221-501-9011@kylheku.com> - 2017-01-07 22:57 +0000
Re: 'Leap Second' to Be Added on New Year's Eve This Year "James R. Kuyper" <jameskuyper@verizon.net> - 2017-01-07 19:06 -0500
Re: 'Leap Second' to Be Added on New Year's Eve This Year Kaz Kylheku <221-501-9011@kylheku.com> - 2017-01-08 06:16 +0000
Re: 'Leap Second' to Be Added on New Year's Eve This Year "James R. Kuyper" <jameskuyper@verizon.net> - 2017-01-08 10:26 -0500
Re: 'Leap Second' to Be Added on New Year's Eve This Year Mark Lloyd <not@mail.invalid> - 2017-01-02 19:05 -0600
Re: 'Leap Second' to Be Added on New Year's Eve This Year "James Wilkinson Sword" <imvalid@somewear.com> - 2017-01-04 00:28 +0000
Re: 'Leap Second' to Be Added on New Year's Eve This Year raltbos@xs4all.nl (Richard Bos) - 2017-01-01 10:01 +0000
Re: 'Leap Second' to Be Added on New Year's Eve This Year Mark Lloyd <not@mail.invalid> - 2016-12-31 14:29 -0600
Re: 'Leap Second' to Be Added on New Year's Eve This Year "James Wilkinson Sword" <imvalid@somewear.com> - 2016-12-31 21:57 +0000
Re: 'Leap Second' to Be Added on New Year's Eve This Year "James R. Kuyper" <jameskuyper@verizon.net> - 2017-01-03 20:06 -0500
Re: 'Leap Second' to Be Added on New Year's Eve This Year "James Wilkinson Sword" <imvalid@somewear.com> - 2017-01-04 15:44 +0000
Re: 'Leap Second' to Be Added on New Year's Eve This Year "James R. Kuyper" <jameskuyper@verizon.net> - 2017-01-04 14:11 -0500
Re: 'Leap Second' to Be Added on New Year's Eve This Year "James Wilkinson Sword" <imvalid@somewear.com> - 2017-01-04 19:58 +0000
Re: 'Leap Second' to Be Added on New Year's Eve This Year Richard Heathfield <rjh@cpax.org.uk> - 2017-01-04 16:17 +0000
Re: 'Leap Second' to Be Added on New Year's Eve This Year "James Wilkinson Sword" <imvalid@somewear.com> - 2017-01-04 21:03 +0000
Re: 'Leap Second' to Be Added on New Year's Eve This Year "Osmium" <r124c4u102@comcast.net> - 2017-01-05 14:15 -0600
Re: 'Leap Second' to Be Added on New Year's Eve This Year "James Wilkinson Sword" <imvalid@somewear.com> - 2017-01-06 01:26 +0000
Re: 'Leap Second' to Be Added on New Year's Eve This Year raltbos@xs4all.nl (Richard Bos) - 2017-01-09 17:12 +0000
Re: 'Leap Second' to Be Added on New Year's Eve This Year Har-dee-har-har <YouMustBeKidding@This.Com> - 2017-01-09 09:53 -0800
Re: 'Leap Second' to Be Added on New Year's Eve This Year "J-P. Rosen" <rosen@adalog.fr> - 2017-01-10 07:20 +0100
Re: 'Leap Second' to Be Added on New Year's Eve This Year "James Wilkinson Sword" <imvalid@somewear.com> - 2017-01-12 23:17 +0000
Re: 'Leap Second' to Be Added on New Year's Eve This Year Tim <timothybil@yahoo.com> - 2017-01-13 00:51 -0600
Re: 'Leap Second' to Be Added on New Year's Eve This Year antispam@math.uni.wroc.pl - 2017-01-05 19:28 +0000
Re: 'Leap Second' to Be Added on New Year's Eve This Year "James Wilkinson Sword" <imvalid@somewear.com> - 2017-01-05 21:41 +0000
Re: 'Leap Second' to Be Added on New Year's Eve This Year Dänk 42Ø <dank@nugget.org> - 2017-01-02 07:08 +0000
Re: 'Leap Second' to Be Added on New Year's Eve This Year Keith Thompson <kst-u@mib.org> - 2017-01-01 23:46 -0800
Re: 'Leap Second' to Be Added on New Year's Eve This Year Dänk 42Ø <dank@nugget.org> - 2017-01-02 21:56 +0000
Re: 'Leap Second' to Be Added on New Year's Eve This Year Keith Thompson <kst-u@mib.org> - 2017-01-02 15:38 -0800
Re: 'Leap Second' to Be Added on New Year's Eve This Year "James R. Kuyper" <jameskuyper@verizon.net> - 2017-01-03 20:26 -0500
Page 5 of 5 — ← Prev page 1 2 3 4 [5]
| From | "James Wilkinson Sword" <imvalid@somewear.com> |
|---|---|
| Date | 2017-01-06 01:26 +0000 |
| Message-ID | <op.ytmd9qx5js98qf@red.lan> |
| In reply to | #7267 |
On Thu, 05 Jan 2017 20:15:14 -0000, Osmium <r124c4u102@comcast.net> wrote: > "James Wilkinson Sword" wrote: > >> Also, I've yet to see a reason why we can't just live with being 1 second >> different to sunrise.... > > I think we can. But since there is more than a minutes error accumulated > during a person's lifetime, I am glad someone is doing this. > > I am fascinated by the fact that they *can* do this. I would assume that > this requires rough agreement (a few milliseconds difference) between > measurements made at different observatories. These are on different > plates of this earth, and these plates are drifting, earthquakes are moving > the observatories, and so on. . > > GPS is not an answer, it intrinsically has the same problems. My god if you got up and had to wait a whole minute extra for the sun to rise, it would sure screw your head up wouldn't it? -- Warning: Do not attempt to stop chainsaw with testicles.
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| From | raltbos@xs4all.nl (Richard Bos) |
|---|---|
| Date | 2017-01-09 17:12 +0000 |
| Message-ID | <5873c46b.1761953@news.xs4all.nl> |
| In reply to | #7258 |
"James Wilkinson Sword" <imvalid@somewear.com> wrote: > Also, I've yet to see a reason why we can't just live with being 1 secon= > d different to sunrise.... Ever heard of GPS? Richard
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| From | Har-dee-har-har <YouMustBeKidding@This.Com> |
|---|---|
| Date | 2017-01-09 09:53 -0800 |
| Message-ID | <o50igi$8ei$1@dont-email.me> |
| In reply to | #7298 |
Richard Bos wrote: > "James Wilkinson Sword" <imvalid@somewear.com> wrote: > >> Also, I've yet to see a reason why we can't just live with being 1 secon= >> d different to sunrise.... > > Ever heard of GPS? The Gap, Inc. (stock symbol) Galapagos Islands, Ecuador - Baltra (Airport Code) Gallons Per Second Ganzpflanzensilage (German: Whole Crop Silage) Gas Pressure Switch General Problem Solver General Purpose Segment General Purpose Separator (at CERN) General Purpose Shelter (temporary, military deployable shelter) Generalized Phase Shift Generalized Processor Sharing Geometrical Product Specifications Geophysical Processor System Geophysical Products System Georgia Performance Standards (Georgia Department of Education) German Peace Society German Philatelic Society German Potato Salad Ghana Police Service Ghostfinder Paranormal Society (UK; est. 2007) Gigahertz Peaked Spectrum (astronomical radio source) Girault, Poupard & Stern (public-key authentication scheme) Girls' Preparatory School (Chattanooga, TN) Gladstone Power Station (QLD, Australia) Global Payment System Global Petroleum Show (trade show; Canada) Global Platinum Securities, LLC Global Precision Snipers (gaming website) Global Priority Service Global Product Strategy (International Council of Chemical Associations) Global Product Support Global Protection System Global Public Square (TV news program) Global Punchout Suite Gloucester Public Schools (Gloucester, MA) Go Pound Sand God's Positioning System Gold Plastic Syndrome (toy breakage) Golden Pussy Syndrome (Women's delusion) Gongshang Primary School (Singapore) Got It, Played It, Sent It (correspondence gaming) Government Policy Statement Graduate Professional Studies (various schools) Grams Per Second Grand Parent Stock (livestock breeding) Grandville Public Schools (Grandville, MI) Grange Primary School (UK) Grants Policy Statement (US DHHS) Graphical Performance Series Graphical Programming Software Gray Platelet Syndrome Great Plains Software Great Public Schools Green Power Switch (renewable energy program) Greenbrier Paranormal Society (Rainelle, WV) Greenridge Primary School (Singapore) Greenwich Public School (various locations) Greenwood Primary School (Singapore) Griffiths Primary School (Singapore) Gross Pay Statement Ground Processing Station Ground Processing System Groundwater Protection Strategy Growth Partnership Services (Frost and Sullivan; various locations) Guangyang Primary School (Singapore) Guaranteed Price Scheme (Sri Lanka) Guelph Police Service (Guelph, Ontario, Canada) Guidance Power Supply Guided Planning System (financial planning) Gunbound Philippine Server (gaming) Gunner's Primary Sight
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| From | "J-P. Rosen" <rosen@adalog.fr> |
|---|---|
| Date | 2017-01-10 07:20 +0100 |
| Message-ID | <o51uci$f1k$1@dont-email.me> |
| In reply to | #7299 |
Le 09/01/2017 à 18:53, Har-dee-har-har a écrit : >> Ever heard of GPS? > > The Gap, Inc. (stock symbol) > Galapagos Islands, Ecuador - Baltra (Airport Code) > Gallons Per Second > Ganzpflanzensilage (German: Whole Crop Silage) [lots of other acronyms stripped] and you miss the Gnat Programming Studio! -- J-P. Rosen Adalog 2 rue du Docteur Lombard, 92441 Issy-les-Moulineaux CEDEX Tel: +33 1 45 29 21 52, Fax: +33 1 45 29 25 00 http://www.adalog.fr
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| From | "James Wilkinson Sword" <imvalid@somewear.com> |
|---|---|
| Date | 2017-01-12 23:17 +0000 |
| Message-ID | <op.yty6zgwijs98qf@red.lan> |
| In reply to | #7298 |
On Mon, 09 Jan 2017 17:12:45 -0000, Richard Bos <raltbos@xs4all.nl> wrote: > "James Wilkinson Sword" <imvalid@somewear.com> wrote: > >> Also, I've yet to see a reason why we can't just live with being 1 secon= >> d different to sunrise.... > > Ever heard of GPS? > > Richard Funny how it was working fine just before they changed the leap second. I'm sure they can make the programming take account of it. -- Computers are like air conditioners: They stop working when you open Windows.
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| From | Tim <timothybil@yahoo.com> |
|---|---|
| Date | 2017-01-13 00:51 -0600 |
| Message-ID | <XnsA6FC8C34D75Atimothybilyahoocom@216.166.97.131> |
| In reply to | #7305 |
"James Wilkinson Sword" <imvalid@somewear.com> wrote in news:op.yty6zgwijs98qf@red.lan: > On Mon, 09 Jan 2017 17:12:45 -0000, Richard Bos <raltbos@xs4all.nl> > wrote: > >> "James Wilkinson Sword" <imvalid@somewear.com> wrote: >> >>> Also, I've yet to see a reason why we can't just live with being 1 >>> secon= d different to sunrise.... >> >> Ever heard of GPS? >> >> Richard > > Funny how it was working fine just before they changed the leap > second. I'm sure they can make the programming take account of it. > Speaking as a former programmer, for 99.9% of the programs out there, adding a Leap Second doesn't really mean anything. Where it gets interesting is when the program is dealing with seconds and portions of seconds - sometimes very minute portions of seconds. Then one had to look very closely at how one handles things. What if your program is interfacing with another program that can't handle the change properly? How do you handle an event that takes less than a second, but spans the time when the Leap Second is added? If the event in question triggers an error condition if it extends for more than a second, how do you tell that this time it is not an error? There are lots of such things to take into account when changing a system time. There are a lot of processes that calculate current position from known velocity and elapsed time from the last time update. When the object is traveling at 17,000 kph, one second makes a big difference is where it thinks it is at. So, yeah, figuring out how to handle a Leap Second causes a lot of hearburn to a lot of very good programmers.
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| From | antispam@math.uni.wroc.pl |
|---|---|
| Date | 2017-01-05 19:28 +0000 |
| Message-ID | <o4m6pr$go9$1@z-news.wcss.wroc.pl> |
| In reply to | #7249 |
In comp.lang.ada James R. Kuyper <jameskuyper@verizon.net> wrote:
> On 12/31/2016 04:57 PM, James Wilkinson Sword wrote:
> > On Thu, 22 Dec 2016 13:43:58 -0000, Mr. Man-wai Chang <toylet.toylet@gmail.com> wrote:
> ...
> >> A "leap second" will be added to the world's official clocks on Dec. 31
> >> at 23 hours, 59 minutes and 59 seconds Coordinated Universal Time (UTC),
> >> which corresponds to 6:59:59 p.m. EST; the clocks will read 23:59:60
> >> before ticking over to midnight. The goal is to keep two different
> >> timescales in sync with each other.
> >>
> >> The units of time had long been defined based on Earth's rotation
> >> relative to distant celestial bodies. But that changed with the
> >> invention of atomic clocks in the mid-20th century; scientists then
> >> decided to base the second on the natural vibrations of the cesium atom.
> >> [How to Build the Most Accurate Atomic Clocks (Video)]
> >>
> >> These two timescales don't match up exactly, however. Measurements show
> >> that, because the moon's gravitational pull and other factors are
> >> gradually slowing Earth's spin, the rotation-based scale loses between
> >> 1.5 and 2 milliseconds per day compared to atomic time ? meaning the two
> >> diverge by a full second every 500 to 750 days.
> >>
> >> Leap seconds are a way to make up for this difference. Since 1972, the
> >> International Earth Rotation and Reference Systems Service (IERS) ? the
>
> That name always struck me as rather funny - it seems to imply that
> they're responsible for making the Earth rotate. What they're actually
> responsible for is keeping track of the Earth's rotation.
>
> >> organization that keeps track of time for the world ? has added 26 leap
> >> seconds to atomic clocks, with the last such insertion coming on June
> >> 30, 2015.
> >>
> >> The aim is to keep the two timescales within 0.9 seconds of each other.
> ...
> > I wish they'd turn their attentions to not turning the clocks back and forth all the fucking time!
>
> If you could make the Earth rotate at a fixed rate, there would be no
> need for leap seconds. It's perfect feasible, though the costs would be
> astronomical. Would you care to pay enough in taxes to make that happen?
Changing _time_ is a nonsense and Earth rotation has little to
do with this:
- most of ordinary time use is conventional and shift of few minutes
will not chage much. AFAICS to accumulate 5 minutes difference
we need hundreds of years, plenty of time to update conventions
if needed. In precision use jumping time is bigger hurdle than
help: astonomers care about differences much smaller than a
second.
- if one really wants to follow Earth rotation time base still
should be continous and at most mapping from "universal" to
"local" time should change. Given that basic time unit is
second we probably should designate one specific moment as
start of rational era and simply measure time in second
relative to this moment. UTC could be reasonable approximation
to rational time, but leap seconds spoil its properties.
--
Waldek Hebisch
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| From | "James Wilkinson Sword" <imvalid@somewear.com> |
|---|---|
| Date | 2017-01-05 21:41 +0000 |
| Message-ID | <op.ytl3vqp2js98qf@red.lan> |
| In reply to | #7266 |
On Thu, 05 Jan 2017 19:28:59 -0000, <antispam@math.uni.wroc.pl> wrote: > In comp.lang.ada James R. Kuyper <jameskuyper@verizon.net> wrote: >> On 12/31/2016 04:57 PM, James Wilkinson Sword wrote: >> > On Thu, 22 Dec 2016 13:43:58 -0000, Mr. Man-wai Chang <toylet.toylet@gmail.com> wrote: >> ... >> >> A "leap second" will be added to the world's official clocks on Dec. 31 >> >> at 23 hours, 59 minutes and 59 seconds Coordinated Universal Time (UTC), >> >> which corresponds to 6:59:59 p.m. EST; the clocks will read 23:59:60 >> >> before ticking over to midnight. The goal is to keep two different >> >> timescales in sync with each other. >> >> >> >> The units of time had long been defined based on Earth's rotation >> >> relative to distant celestial bodies. But that changed with the >> >> invention of atomic clocks in the mid-20th century; scientists then >> >> decided to base the second on the natural vibrations of the cesium atom. >> >> [How to Build the Most Accurate Atomic Clocks (Video)] >> >> >> >> These two timescales don't match up exactly, however. Measurements show >> >> that, because the moon's gravitational pull and other factors are >> >> gradually slowing Earth's spin, the rotation-based scale loses between >> >> 1.5 and 2 milliseconds per day compared to atomic time ? meaning the two >> >> diverge by a full second every 500 to 750 days. >> >> >> >> Leap seconds are a way to make up for this difference. Since 1972, the >> >> International Earth Rotation and Reference Systems Service (IERS) ? the >> >> That name always struck me as rather funny - it seems to imply that >> they're responsible for making the Earth rotate. What they're actually >> responsible for is keeping track of the Earth's rotation. >> >> >> organization that keeps track of time for the world ? has added 26 leap >> >> seconds to atomic clocks, with the last such insertion coming on June >> >> 30, 2015. >> >> >> >> The aim is to keep the two timescales within 0.9 seconds of each other. >> ... >> > I wish they'd turn their attentions to not turning the clocks back and forth all the fucking time! >> >> If you could make the Earth rotate at a fixed rate, there would be no >> need for leap seconds. It's perfect feasible, though the costs would be >> astronomical. Would you care to pay enough in taxes to make that happen? > > Changing _time_ is a nonsense and Earth rotation has little to > do with this: > > - most of ordinary time use is conventional and shift of few minutes > will not chage much. AFAICS to accumulate 5 minutes difference > we need hundreds of years, plenty of time to update conventions > if needed. In precision use jumping time is bigger hurdle than > help: astonomers care about differences much smaller than a > second. > - if one really wants to follow Earth rotation time base still > should be continous and at most mapping from "universal" to > "local" time should change. Given that basic time unit is > second we probably should designate one specific moment as > start of rational era and simply measure time in second > relative to this moment. UTC could be reasonable approximation > to rational time, but leap seconds spoil its properties. +1 -- Money can't buy you true love. It does however put you in a good bargaining position.
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| From | Dänk 42Ø <dank@nugget.org> |
|---|---|
| Date | 2017-01-02 07:08 +0000 |
| Message-ID | <GoGdnf_on-zkYfTFnZ2dnUU7-X3NnZ2d@earthlink.com> |
| In reply to | #7182 |
On 12/22/2016 01:43 PM, Mr. Man-wai Chang wrote: > 'Leap Second' to Be Added on New Year's Eve This Year > > Full story: > <http://www.space.com/33361-leap-second-2016-atomic-clocks.html> > > Revelers will get to celebrate New Year's Eve for a tiny bit longer > than usual this year. > > A "leap second" will be added to the world's official clocks on Dec. 31 > at 23 hours, 59 minutes and 59 seconds Coordinated Universal Time (UTC), > which corresponds to 6:59:59 p.m. EST; the clocks will read 23:59:60 > before ticking over to midnight. The goal is to keep two different > timescales in sync with each other. My question is how this will affect computer programs that convert Unix Julian time (which keeps time in seconds since 00:00:00 UTC 01 Jan 1970). For example, I have various Perl modules that convert Unix time to readable timestamps. If my module doesn't include for the leap second, will my timestamps be one second off? I assume they'll update the myriad of programming language modules, but how long will this take? For now, I'll assume the current Perl module has been updated. (BTW, I was watching the Berlin clock on timeanddate.com, and their clock went from 23:59:59 to 00:00:00 -- there was no "23:59:60").
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| From | Keith Thompson <kst-u@mib.org> |
|---|---|
| Date | 2017-01-01 23:46 -0800 |
| Message-ID | <lnpok5x5tz.fsf@kst-u.example.com> |
| In reply to | #7227 |
Dänk 42Ø <dank@nugget.org> writes:
[...]
> My question is how this will affect computer programs that convert Unix
> Julian time (which keeps time in seconds since 00:00:00 UTC 01 Jan
> 1970).
That's just Unix time; it's not "Julian".
> For example, I have various Perl modules that convert Unix time to
> readable timestamps. If my module doesn't include for the leap second,
> will my timestamps be one second off? I assume they'll update the
> myriad of programming language modules, but how long will this take?
> For now, I'll assume the current Perl module has been updated.
Typically Unix systems ignore leap seconds. For example, on my system's
timestamp as I write this is 1483342650, though allowing for the 37
intervening leap seconds, 1970-01-01 00:00:00 UTC was actually
1483342687 seconds ago. The slightly incorrect representation of old
date isn't much of a problem in practice.
The system clock was probably adjusted gradually during the period
before and after the leap second.
> (BTW, I was watching the Berlin clock on timeanddate.com, and their
> clock went from 23:59:59 to 00:00:00 -- there was no "23:59:60").
time.gov showed 23:59:60.
--
Keith Thompson (The_Other_Keith) kst-u@mib.org <http://www.ghoti.net/~kst>
Working, but not speaking, for JetHead Development, Inc.
"We must do something. This is something. Therefore, we must do this."
-- Antony Jay and Jonathan Lynn, "Yes Minister"
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| From | Dänk 42Ø <dank@nugget.org> |
|---|---|
| Date | 2017-01-02 21:56 +0000 |
| Message-ID | <zNudnUt2Lts1UffFnZ2dnUU7-WHNnZ2d@earthlink.com> |
| In reply to | #7228 |
On 01/02/2017 07:46 AM, Keith Thompson wrote: > Dänk 42Ø <dank@nugget.org> writes: > [...] >> My question is how this will affect computer programs that convert Unix >> Julian time (which keeps time in seconds since 00:00:00 UTC 01 Jan >> 1970). > > That's just Unix time; it's not "Julian". > >> For example, I have various Perl modules that convert Unix time to >> readable timestamps. If my module doesn't include for the leap second, >> will my timestamps be one second off? I assume they'll update the >> myriad of programming language modules, but how long will this take? >> For now, I'll assume the current Perl module has been updated. > > Typically Unix systems ignore leap seconds. For example, on my system's > timestamp as I write this is 1483342650, though allowing for the 37 > intervening leap seconds, 1970-01-01 00:00:00 UTC was actually > 1483342687 seconds ago. The slightly incorrect representation of old > date isn't much of a problem in practice. > > The system clock was probably adjusted gradually during the period > before and after the leap second. But since computers store files with Unix time strings, how is is that a recently saved file shows the correct current time and is not 37 seconds off? Obviously, the software is accounting for those leap seconds? Or maybe you're referring to the SYSTEM time, which is adjusted, but makes dating really old files difficult since I don't what system they came from or whether they adjusted for leap seconds. A very trivial matter, especially with old files, but a very important one today, where files are timestamped down to the milli- second. >> (BTW, I was watching the Berlin clock on timeanddate.com, and their >> clock went from 23:59:59 to 00:00:00 -- there was no "23:59:60"). > > time.gov showed 23:59:60. Shoulda gone there. I was especially interested in Berlin's New Year, as I was following the German news to see whether a terrorist attack occurred at that moment.
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| From | Keith Thompson <kst-u@mib.org> |
|---|---|
| Date | 2017-01-02 15:38 -0800 |
| Message-ID | <lnzij9uj6v.fsf@kst-u.example.com> |
| In reply to | #7236 |
Dänk 42Ø <dank@nugget.org> writes:
> On 01/02/2017 07:46 AM, Keith Thompson wrote:
[...]
>> The system clock was probably adjusted gradually during the period
>> before and after the leap second.
>
> But since computers store files with Unix time strings, how is is that
> a recently saved file shows the correct current time and is not 37
> seconds off?
In fact the timestamp of a file created in 1970 *is* 37 seconds off.
I don't have any files that old, but the timestamp of a file created
in 2016 is now 1 second off, and will be 2 seconds off after the
next leap second.
I'll bet you didn't notice. As long as timestamps are monotonically
increasing, it doesn't significantly matter.
If you need to record timestamps from several years ago with higher
precision, and allowing for leap seconds, there are other time
representations you can use. It just happens that Unix filesystems
don't typically use them (though it's entirely possible that there
are some I don't know about that do).
Relevance to C: The C standard says only that time_t, the type
returned by the time() function, is a real time (integer or
floating-point) capable of representing times. POSIX specifically
says that leap seconds are ignored. This implies, for example,
that time(NULL) % 3600 is the number of seconds since the top of
the hour, and that system software doesn't have to allow for past
leap seconds (which would be inconvenient) or future leap seconds
(which would be impossible).
[...]
--
Keith Thompson (The_Other_Keith) kst-u@mib.org <http://www.ghoti.net/~kst>
Working, but not speaking, for JetHead Development, Inc.
"We must do something. This is something. Therefore, we must do this."
-- Antony Jay and Jonathan Lynn, "Yes Minister"
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| From | "James R. Kuyper" <jameskuyper@verizon.net> |
|---|---|
| Date | 2017-01-03 20:26 -0500 |
| Message-ID | <e5184084-6cd5-37a7-3906-2d330580bdab@verizon.net> |
| In reply to | #7227 |
On 01/02/2017 02:08 AM, Dänk 42Ø wrote: ... > (BTW, I was watching the Berlin clock on timeanddate.com, and their > clock went from 23:59:59 to 00:00:00 -- there was no "23:59:60"). The leap second occurred at the same time all around the world, not at the same local time (that would have been a nightmare for anybody who needs to keep track of local time in multiple time zones with sub-second precision!). The Berlin clock should therefore have gone from 00:59:59 to 00:59:60 (if it correctly reflected leap seconds), since it's in the CET time zone.
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