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Re: Measuring time

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Dr J R Stockton wrote:

> On Tuesday, October 24, 2017 at 11:59:40 PM UTC+1, Thomas 'PointedEars'
> Lahn wrote:
>> Dr J R Stockton wrote:
>> > On Thursday, October 19, 2017 at 9:58:26 PM UTC+1, Thomas 'PointedEars'
>> > Lahn wrote:
>> 
>> Attribution line, not attribution novel.
> 
> OAF.

No, I do not think that the Open Access Framework has something to do with 
it.
 
>> >  > Apropos, it had just occurred to me (when reading that the first
>> >  > time the
>> >> on-board cesium clocks of the GPS NTS-2 satellite were tested was on
>> >> “day 190, 1977”) that you can obtain the date for day N of year Y
>> >> using
>> >>   new Date(Y, 0, N)
>> > The likelihood of that is fairly obvious on considering
>> > 
>> > ECMA-262-1, Jun 1997, 15.9.1.12 MakeDay(year, month, date), list entry
>> > 1 or
>> > ECMA-262-7, Jun 2016, 20.3.1.13 MakeDay (year, month, date), list entry
>> > 1 or I suppose the corresponding parts of all other ECMA-262.
>> 
>> (You are preaching to the choir.)  I thought that to be obvious.
> 
> It is, and it was well known long ago to many of us here,

It turns out that the MakeDay() algorithm was never the reason, but the Date 
constructor itself:  From

<http://www.ecma-international.org/publications/files/ECMA-ST-ARCH/ECMA-262,
%201st%20edition,%20June%201997.pdf>

to

,-<http://www.ecma-international.org/ecma-262/8.0/#sec-date-year-month-date-hours-minutes-seconds-ms>
| 
| […]
| h. If y is not NaN and 0 ≤ ToInteger(y) ≤ 99, then let yr be
|    1900+ToInteger(y); otherwise, let yr be y.

> so why did you write "it had just occurred to me",

That follows from my description.

> which implies surprise? 

More like coincidence in this case.

> Perhaps you meant "I had just remembered".

No.

>> > IIRC, new Date(Y, 0, N) fails for years 0 to 99;
> 
> <<< Of course, that is not a true failure, as can be seen
>     by searching the Standard for the string "1900".  It is
>     just an inanity of the Originators, as is getYear not
>     doing what getFullYear was later added to do.

ACK.
 
>> It fails for those years in V8 JavaScript 5.7.492.63 in Chromium
>> 57.0.2987.98 on Debian/Devuan GNU+Linux in that they are considered
>> the years 1900 to 1999 CE instead (also see below):
>> 
>> | -> new Date(99, 0, 1)
>> | <- Fri Jan 01 1999 00:00:00 GMT+0100 (CET)
>> 
>> However, while “new Date(0, 0, 1)” cannot be used to produce January 1,
>> 1 BCE according to the Proleptic Gregorian calendar, it is apparently
>> possible to do that in another way:
>> 
>> | -> var d = new Date(0, 0, 1); console.log(d); d.setFullYear(0);
>> |    console.log(d);
>> | Mon Jan 01 1900 00:00:00 GMT+0100 (CET)
>> | Sat Jan 01    0 00:00:00 GMT+0100 (CET)
> 
> It is easier to use   var d = new Date(100, -1200, 1)  or some
> variant thereof, such as   var d = new Date(-100, 1200, 1) ;
> one can indeed use var d = new Date(400, 0, 1-400*365.2425) .
> And easier still : var d = new Date(-1, 12, 1) .

Easier maybe, but not as reliable, and certainly harder to maintain.
A wrapper constructor that calls setFullYear() if necessary appears to be 
the better approach.

>> <https://en.wikipedia.org/wiki/1_BC> says that it was a Saturday indeed.
>> 
>> > and MD is wrong for most of Year 0.
>> 
>> That is a matter of interpretation or, if understood as specified, it
>> does not appear to be the case in that implementation (see above). 
>> According to Wikipedia, 1999-01-01 CE *was* a Monday indeed:
                           ^^^^
> But, according to my relevant IoP diary, 1999-01-01 was a Friday.

Yes; this was a typo, as you can see if you consider the source code.
 
> The obvious handy authority for the secular proleptic Gregorian year
> zero is the civil calendar for years 2000 += n*28, for |n|<4.  That
> IoP diary says that the year 2000 was Saturday to Sunday; therefore
> 2001-001 = 2001-W01-1 (sic) was a Monday, as was fairly well
> known at the time.

I do not follow.

-- 
PointedEars
FAQ: <http://PointedEars.de/faq> | <http://PointedEars.de/es-matrix>
<https://github.com/PointedEars> | <http://PointedEars.de/wsvn/>
Twitter: @PointedEars2 | Please do not cc me./Bitte keine Kopien per E-Mail.

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Random numbers emf <emfril@gmail.com> - 2017-10-19 07:35 -0400
  Re: Random numbers Julio Di Egidio <julio@diegidio.name> - 2017-10-19 05:03 -0700
  Re: Random numbers Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2017-10-19 21:06 +0200
    Re: Random numbers "Michael Haufe (TNO)" <tno@thenewobjective.com> - 2017-10-19 12:10 -0700
      Re: Random numbers Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2017-10-19 22:04 +0200
        Re: Random numbers "Michael Haufe (TNO)" <tno@thenewobjective.com> - 2017-10-19 13:41 -0700
          Measuring time (was: Random numbers) Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2017-10-19 22:58 +0200
            Re: Measuring time (was: Random numbers) Dr J R Stockton <J.R.Stockton@physics.org> - 2017-10-24 13:05 -0700
              Re: Measuring time Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2017-10-25 00:59 +0200
                Re: Measuring time Dr J R Stockton <J.R.Stockton@physics.org> - 2017-10-25 13:36 -0700
                Re: Measuring time Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2017-10-26 19:21 +0200
              Re: Measuring time (was: Random numbers) Hans-Georg Michna <hans-georgNoEmailPlease@michna.com> - 2017-10-26 10:45 +0200
                Re: Measuring time (was: Random numbers) "Evertjan." <exxjxw.hannivoort@inter.nl.net> - 2017-10-26 12:27 +0200
                Re: Measuring time (was: Random numbers) Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2017-10-26 19:04 +0200
                Re: Measuring time (was: Random numbers) Hans-Georg Michna <hans-georg@michna.com> - 2017-10-28 11:05 +0200
                Re: Measuring time (was: Random numbers) Dr J R Stockton <J.R.Stockton@physics.org> - 2017-10-29 03:03 -0700
                Re: Measuring time (was: Random numbers) Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2017-10-29 17:56 +0100
                Re: Measuring time (was: Random numbers) dr.j.r.stockton@gmail.com - 2017-10-29 15:12 -0700
                Re: Measuring time Sam E <why.should.this@be.email.invalid> - 2017-10-29 17:35 -0500
                Re: Measuring time (was: Random numbers) Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2017-10-30 13:00 +0100
                Re: Measuring time (was: Random numbers) Tim Slattery <tim@risingdove.com> - 2017-10-26 14:13 -0400
  Re: Random numbers Ben Bacarisse <ben.usenet@bsb.me.uk> - 2017-10-19 22:21 +0100
    Re: Random numbers Julio Di Egidio <julio@diegidio.name> - 2017-10-19 22:25 -0700
      Re: Random numbers "Chris M. Thomasson" <invalid_chris_thomasson@invalid.invalid> - 2017-10-20 21:52 -0700
        Re: Random numbers Julio Di Egidio <julio@diegidio.name> - 2017-10-20 22:40 -0700
          Re: Random numbers "Chris M. Thomasson" <invalid_chris_thomasson@invalid.invalid> - 2017-10-21 12:40 -0700
            Re: Random numbers Julio Di Egidio <julio@diegidio.name> - 2017-10-21 12:57 -0700
              Re: Random numbers Julio Di Egidio <julio@diegidio.name> - 2017-10-21 12:59 -0700
                Re: Random numbers "Chris M. Thomasson" <invalid_chris_thomasson@invalid.invalid> - 2017-10-22 16:37 -0700
                Re: Random numbers Julio Di Egidio <julio@diegidio.name> - 2017-10-22 17:23 -0700
  Re: Random numbers emf <emfril@gmail.com> - 2017-10-20 20:32 -0400
    Re: Random numbers "Michael Haufe (TNO)" <tno@thenewobjective.com> - 2017-10-21 09:47 -0700
      Re: Random numbers emf <emfril@gmail.com> - 2017-10-22 14:55 -0400
        Re: Random numbers emf <emfril@gmail.com> - 2017-10-27 22:23 -0400
          Re: Random numbers Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2017-10-28 18:54 +0200

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