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Groups > comp.lang.python > #111197 > unrolled thread
| Started by | Rob Gaddi <rgaddi@highlandtechnology.invalid> |
|---|---|
| First post | 2016-07-07 23:46 +0000 |
| Last post | 2016-07-19 23:16 -0400 |
| Articles | 20 on this page of 103 — 19 participants |
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Clean Singleton Docstrings Rob Gaddi <rgaddi@highlandtechnology.invalid> - 2016-07-07 23:46 +0000
Re: Clean Singleton Docstrings Steven D'Aprano <steve@pearwood.info> - 2016-07-08 12:53 +1000
Re: Clean Singleton Docstrings Michael Selik <michael.selik@gmail.com> - 2016-07-07 23:43 -0400
Re: Clean Singleton Docstrings Rob Gaddi <rgaddi@highlandtechnology.invalid> - 2016-07-08 16:57 +0000
Re: Clean Singleton Docstrings Ethan Furman <ethan@stoneleaf.us> - 2016-07-08 13:00 -0700
Re: Clean Singleton Docstrings Peter Otten <__peter__@web.de> - 2016-07-08 09:38 +0200
Re: Clean Singleton Docstrings Steven D'Aprano <steve@pearwood.info> - 2016-07-08 19:20 +1000
Re: Clean Singleton Docstrings Rob Gaddi <rgaddi@highlandtechnology.invalid> - 2016-07-08 16:47 +0000
Re: Clean Singleton Docstrings Lawrence D’Oliveiro <lawrencedo99@gmail.com> - 2016-07-13 15:42 -0700
Re: Clean Singleton Docstrings Peter Otten <__peter__@web.de> - 2016-07-14 01:54 +0200
Re: Clean Singleton Docstrings Rustom Mody <rustompmody@gmail.com> - 2016-07-15 21:04 -0700
Re: Clean Singleton Docstrings Ethan Furman <ethan@stoneleaf.us> - 2016-07-15 21:20 -0700
Re: Clean Singleton Docstrings Rustom Mody <rustompmody@gmail.com> - 2016-07-15 22:51 -0700
Re: Clean Singleton Docstrings Lawrence D’Oliveiro <lawrencedo99@gmail.com> - 2016-07-15 23:19 -0700
Re: Clean Singleton Docstrings Chris Angelico <rosuav@gmail.com> - 2016-07-16 16:29 +1000
Re: Clean Singleton Docstrings Random832 <random832@fastmail.com> - 2016-07-16 02:53 -0400
Re: Clean Singleton Docstrings Steven D'Aprano <steve@pearwood.info> - 2016-07-16 18:54 +1000
Re: Clean Singleton Docstrings Steven D'Aprano <steve@pearwood.info> - 2016-07-16 19:46 +1000
What exactly is "exact" (was Clean Singleton Docstrings) Rustom Mody <rustompmody@gmail.com> - 2016-07-17 21:16 -0700
Re: What exactly is "exact" (was Clean Singleton Docstrings) Chris Angelico <rosuav@gmail.com> - 2016-07-18 14:35 +1000
Re: What exactly is "exact" (was Clean Singleton Docstrings) Rustom Mody <rustompmody@gmail.com> - 2016-07-17 22:37 -0700
Re: What exactly is "exact" (was Clean Singleton Docstrings) Chris Angelico <rosuav@gmail.com> - 2016-07-18 15:48 +1000
Re: What exactly is "exact" (was Clean Singleton Docstrings) Marko Rauhamaa <marko@pacujo.net> - 2016-07-18 09:21 +0300
Re: What exactly is "exact" (was Clean Singleton Docstrings) Random832 <random832@fastmail.com> - 2016-07-18 09:32 -0400
Re: What exactly is "exact" (was Clean Singleton Docstrings) Ben Finney <ben+python@benfinney.id.au> - 2016-07-18 14:46 +1000
Re: What exactly is "exact" (was Clean Singleton Docstrings) Rustom Mody <rustompmody@gmail.com> - 2016-07-17 22:22 -0700
Re: What exactly is "exact" (was Clean Singleton Docstrings) Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2016-07-18 19:29 +1000
Re: What exactly is "exact" (was Clean Singleton Docstrings) Marko Rauhamaa <marko@pacujo.net> - 2016-07-18 13:00 +0300
Re: What exactly is "exact" (was Clean Singleton Docstrings) Chris Angelico <rosuav@gmail.com> - 2016-07-18 20:15 +1000
Re: What exactly is "exact" (was Clean Singleton Docstrings) Rustom Mody <rustompmody@gmail.com> - 2016-07-18 03:24 -0700
Re: What exactly is "exact" (was Clean Singleton Docstrings) Chris Angelico <rosuav@gmail.com> - 2016-07-18 20:37 +1000
Re: What exactly is "exact" (was Clean Singleton Docstrings) Marko Rauhamaa <marko@pacujo.net> - 2016-07-18 14:38 +0300
Re: What exactly is "exact" (was Clean Singleton Docstrings) Peter Otten <__peter__@web.de> - 2016-07-18 14:58 +0200
Re: What exactly is "exact" (was Clean Singleton Docstrings) Steven D'Aprano <steve@pearwood.info> - 2016-07-19 13:42 +1000
Re: What exactly is "exact" (was Clean Singleton Docstrings) Rustom Mody <rustompmody@gmail.com> - 2016-07-18 21:58 -0700
Re: What exactly is "exact" (was Clean Singleton Docstrings) Chris Angelico <rosuav@gmail.com> - 2016-07-19 15:30 +1000
Floating point equality [was Re: What exactly is "exact" (was Clean Singleton Docstrings)] Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2016-07-20 15:42 +1000
Re: Floating point equality [was Re: What exactly is "exact" (was Clean Singleton Docstrings)] Chris Angelico <rosuav@gmail.com> - 2016-07-20 16:11 +1000
Re: Floating point equality [was Re: What exactly is "exact" (was Clean Singleton Docstrings)] Antoon Pardon <antoon.pardon@rece.vub.ac.be> - 2016-07-20 09:09 +0200
Re: Floating point equality [was Re: What exactly is "exact" (was Clean Singleton Docstrings)] Marko Rauhamaa <marko@pacujo.net> - 2016-07-20 10:25 +0300
Re: Floating point equality [was Re: What exactly is "exact" (was Clean Singleton Docstrings)] Steven D'Aprano <steve@pearwood.info> - 2016-07-20 22:47 +1000
Re: Floating point equality [was Re: What exactly is "exact" (was Clean Singleton Docstrings)] Marko Rauhamaa <marko@pacujo.net> - 2016-07-20 16:54 +0300
Re: Floating point equality [was Re: What exactly is "exact" (was Clean Singleton Docstrings)] Chris Angelico <rosuav@gmail.com> - 2016-07-21 00:26 +1000
Re: Floating point equality [was Re: What exactly is "exact" (was Clean Singleton Docstrings)] Marko Rauhamaa <marko@pacujo.net> - 2016-07-20 17:59 +0300
Re: Floating point equality [was Re: What exactly is "exact" (was Clean Singleton Docstrings)] Rustom Mody <rustompmody@gmail.com> - 2016-07-20 22:38 -0700
Re: Floating point equality [was Re: What exactly is "exact" (was Clean Singleton Docstrings)] Marko Rauhamaa <marko@pacujo.net> - 2016-07-21 10:52 +0300
Re: Floating point equality [was Re: What exactly is "exact" (was Clean Singleton Docstrings)] Chris Angelico <rosuav@gmail.com> - 2016-07-21 18:46 +1000
Re: Floating point equality [was Re: What exactly is "exact" (was Clean Singleton Docstrings)] Marko Rauhamaa <marko@pacujo.net> - 2016-07-21 12:09 +0300
Re: Floating point equality [was Re: What exactly is "exact" (was Clean Singleton Docstrings)] Ben Bacarisse <ben.usenet@bsb.me.uk> - 2016-07-22 00:54 +0100
Re: Floating point equality [was Re: What exactly is "exact" (was Clean Singleton Docstrings)] Chris Kaynor <ckaynor@zindagigames.com> - 2016-07-21 17:43 -0700
Re: Floating point equality [was Re: What exactly is "exact" (was Clean Singleton Docstrings)] Ben Bacarisse <ben.usenet@bsb.me.uk> - 2016-07-22 17:14 +0100
Re: Floating point equality [was Re: What exactly is "exact" (was Clean Singleton Docstrings)] Rustom Mody <rustompmody@gmail.com> - 2016-07-20 22:28 -0700
Re: Floating point equality [was Re: What exactly is "exact" (was Clean Singleton Docstrings)] Chris Angelico <rosuav@gmail.com> - 2016-07-21 15:35 +1000
Re: Floating point equality [was Re: What exactly is "exact" (was Clean Singleton Docstrings)] Rustom Mody <rustompmody@gmail.com> - 2016-07-20 22:52 -0700
Re: Floating point equality [was Re: What exactly is "exact" (was Clean Singleton Docstrings)] Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2016-07-21 16:34 +1000
Re: Floating point equality [was Re: What exactly is "exact" (was Clean Singleton Docstrings)] Rustom Mody <rustompmody@gmail.com> - 2016-07-21 06:14 -0700
Re: Floating point equality [was Re: What exactly is "exact" (was Clean Singleton Docstrings)] Steven D'Aprano <steve@pearwood.info> - 2016-07-22 02:10 +1000
Re: What exactly is "exact" (was Clean Singleton Docstrings) Chris Angelico <rosuav@gmail.com> - 2016-07-19 15:27 +1000
Re: What exactly is "exact" (was Clean Singleton Docstrings) Rustom Mody <rustompmody@gmail.com> - 2016-07-18 03:14 -0700
Re: What exactly is "exact" (was Clean Singleton Docstrings) Ian Kelly <ian.g.kelly@gmail.com> - 2016-07-18 09:25 -0600
Re: What exactly is "exact" (was Clean Singleton Docstrings) Marko Rauhamaa <marko@pacujo.net> - 2016-07-18 18:40 +0300
Re: What exactly is "exact" (was Clean Singleton Docstrings) Marko Rauhamaa <marko@pacujo.net> - 2016-07-18 18:55 +0300
Re: What exactly is "exact" (was Clean Singleton Docstrings) Ian Kelly <ian.g.kelly@gmail.com> - 2016-07-18 11:13 -0600
Re: What exactly is "exact" (was Clean Singleton Docstrings) Marko Rauhamaa <marko@pacujo.net> - 2016-07-18 21:58 +0300
Re: What exactly is "exact" (was Clean Singleton Docstrings) Rustom Mody <rustompmody@gmail.com> - 2016-07-18 17:36 -0700
Re: What exactly is "exact" (was Clean Singleton Docstrings) Steven D'Aprano <steve@pearwood.info> - 2016-07-19 13:16 +1000
Re: What exactly is "exact" (was Clean Singleton Docstrings) Rustom Mody <rustompmody@gmail.com> - 2016-07-18 20:26 -0700
Re: What exactly is "exact" (was Clean Singleton Docstrings) Gene Heskett <gheskett@shentel.net> - 2016-07-19 01:22 -0400
Re: What exactly is "exact" (was Clean Singleton Docstrings) Lawrence D’Oliveiro <lawrencedo99@gmail.com> - 2016-07-19 10:46 -0700
Re: What exactly is "exact" (was Clean Singleton Docstrings) Gene Heskett <gheskett@shentel.net> - 2016-07-19 16:35 -0400
Re: What exactly is "exact" (was Clean Singleton Docstrings) Marko Rauhamaa <marko@pacujo.net> - 2016-07-20 01:17 +0300
Re: What exactly is "exact" (was Clean Singleton Docstrings) Random832 <random832@fastmail.com> - 2016-07-19 23:15 -0400
Re: What exactly is "exact" (was Clean Singleton Docstrings) Marko Rauhamaa <marko@pacujo.net> - 2016-07-20 10:16 +0300
Re: What exactly is "exact" (was Clean Singleton Docstrings) Random832 <random832@fastmail.com> - 2016-07-20 10:00 -0400
Re: What exactly is "exact" (was Clean Singleton Docstrings) Gregory Ewing <greg.ewing@canterbury.ac.nz> - 2016-07-21 10:46 +1200
Re: What exactly is "exact" (was Clean Singleton Docstrings) Ian Kelly <ian.g.kelly@gmail.com> - 2016-07-19 16:27 -0600
Re: What exactly is "exact" (was Clean Singleton Docstrings) Marko Rauhamaa <marko@pacujo.net> - 2016-07-20 02:09 +0300
Re: What exactly is "exact" (was Clean Singleton Docstrings) alister <alister.ware@ntlworld.com> - 2016-07-20 13:24 +0000
Re: What exactly is "exact" (was Clean Singleton Docstrings) Steven D'Aprano <steve@pearwood.info> - 2016-07-21 14:04 +1000
Re: What exactly is "exact" (was Clean Singleton Docstrings) Lawrence D’Oliveiro <lawrencedo99@gmail.com> - 2016-07-19 17:01 -0700
Re: What exactly is "exact" (was Clean Singleton Docstrings) Gregory Ewing <greg.ewing@canterbury.ac.nz> - 2016-07-20 11:07 +1200
Re: What exactly is "exact" (was Clean Singleton Docstrings) Marko Rauhamaa <marko@pacujo.net> - 2016-07-20 02:20 +0300
Re: What exactly is "exact" (was Clean Singleton Docstrings) Steven D'Aprano <steve@pearwood.info> - 2016-07-19 13:03 +1000
Re: What exactly is "exact" (was Clean Singleton Docstrings) Random832 <random832@fastmail.com> - 2016-07-18 09:25 -0400
Re: What exactly is "exact" (was Clean Singleton Docstrings) Steven D'Aprano <steve@pearwood.info> - 2016-07-19 13:21 +1000
Re: What exactly is "exact" (was Clean Singleton Docstrings) Ben Finney <ben+python@benfinney.id.au> - 2016-07-19 10:21 +1000
Re: Clean Singleton Docstrings Chris Angelico <rosuav@gmail.com> - 2016-07-16 17:27 +1000
Re: Clean Singleton Docstrings Marko Rauhamaa <marko@pacujo.net> - 2016-07-16 10:58 +0300
Re: Clean Singleton Docstrings Random832 <random832@fastmail.com> - 2016-07-16 14:04 -0400
Re: Clean Singleton Docstrings Marko Rauhamaa <marko@pacujo.net> - 2016-07-16 21:43 +0300
Re: Clean Singleton Docstrings Chris Angelico <rosuav@gmail.com> - 2016-07-17 07:02 +1000
Re: Clean Singleton Docstrings Marko Rauhamaa <marko@pacujo.net> - 2016-07-17 00:27 +0300
Re: Clean Singleton Docstrings Chris Angelico <rosuav@gmail.com> - 2016-07-17 08:18 +1000
Re: Clean Singleton Docstrings Marko Rauhamaa <marko@pacujo.net> - 2016-07-17 10:41 +0300
Re: Clean Singleton Docstrings Chris Angelico <rosuav@gmail.com> - 2016-07-17 17:51 +1000
Re: Clean Singleton Docstrings Random832 <random832@fastmail.com> - 2016-07-17 04:03 -0400
Re: Clean Singleton Docstrings Steven D'Aprano <steve@pearwood.info> - 2016-07-17 20:35 +1000
Re: Clean Singleton Docstrings Random832 <random832@fastmail.com> - 2016-07-17 04:08 -0400
Re: Clean Singleton Docstrings Chris Angelico <rosuav@gmail.com> - 2016-07-17 18:44 +1000
Re: Clean Singleton Docstrings Ian Kelly <ian.g.kelly@gmail.com> - 2016-07-13 18:25 -0600
Re: Clean Singleton Docstrings Peter Otten <__peter__@web.de> - 2016-07-08 09:44 +0200
Re: Clean Singleton Docstrings Rustom Mody <rustompmody@gmail.com> - 2016-07-08 01:53 -0700
Re: What exactly is "exact" (was Clean Singleton Docstrings) Gene Heskett <gheskett@shentel.net> - 2016-07-19 23:16 -0400
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| From | Marko Rauhamaa <marko@pacujo.net> |
|---|---|
| Date | 2016-07-18 18:40 +0300 |
| Subject | Re: What exactly is "exact" (was Clean Singleton Docstrings) |
| Message-ID | <87d1mbrm3p.fsf@elektro.pacujo.net> |
| In reply to | #111609 |
Ian Kelly <ian.g.kelly@gmail.com>: > Off-topic, c being a fundamental constant is actually in the latter > category. Its *exact* value is 299792458 m/s. > > The length of the meter, on the other hand, is defined as the distance > traveled by light in a vacuum in 1/299792458 seconds and is subject to > the precision of measurements. Since both c and the second are exact magnitudes, so is the meter. The second [...] is quantitatively defined in terms of exactly 9,192,631,770 periods of a certain frequency of radiation from the caesium atom: a so-called atomic clock. <URL: https://en.wikipedia.org/wiki/Second> Marko
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| From | Marko Rauhamaa <marko@pacujo.net> |
|---|---|
| Date | 2016-07-18 18:55 +0300 |
| Subject | Re: What exactly is "exact" (was Clean Singleton Docstrings) |
| Message-ID | <877fcjrldc.fsf@elektro.pacujo.net> |
| In reply to | #111610 |
Marko Rauhamaa <marko@pacujo.net>: > Ian Kelly <ian.g.kelly@gmail.com>: >> Off-topic, c being a fundamental constant is actually in the latter >> category. Its *exact* value is 299792458 m/s. >> >> The length of the meter, on the other hand, is defined as the distance >> traveled by light in a vacuum in 1/299792458 seconds and is subject to >> the precision of measurements. > > Since both c and the second are exact magnitudes, so is the meter. > > The second [...] is quantitatively defined in terms of exactly > 9,192,631,770 periods of a certain frequency of radiation from the > caesium atom: a so-called atomic clock. > <URL: https://en.wikipedia.org/wiki/Second> Which would became immediately apparent if you programmed in Scheme. One meter is equal to the wavelength of said magnitude times: 9192631770/299792458 ==> 656616555/21413747 (exact? 9192631770/299792458) ==> #t Marko
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| From | Ian Kelly <ian.g.kelly@gmail.com> |
|---|---|
| Date | 2016-07-18 11:13 -0600 |
| Subject | Re: What exactly is "exact" (was Clean Singleton Docstrings) |
| Message-ID | <mailman.78.1468862036.2307.python-list@python.org> |
| In reply to | #111611 |
On Mon, Jul 18, 2016 at 9:55 AM, Marko Rauhamaa <marko@pacujo.net> wrote: > Marko Rauhamaa <marko@pacujo.net>: > >> Ian Kelly <ian.g.kelly@gmail.com>: >>> Off-topic, c being a fundamental constant is actually in the latter >>> category. Its *exact* value is 299792458 m/s. >>> >>> The length of the meter, on the other hand, is defined as the distance >>> traveled by light in a vacuum in 1/299792458 seconds and is subject to >>> the precision of measurements. >> >> Since both c and the second are exact magnitudes, so is the meter. >> >> The second [...] is quantitatively defined in terms of exactly >> 9,192,631,770 periods of a certain frequency of radiation from the >> caesium atom: a so-called atomic clock. >> <URL: https://en.wikipedia.org/wiki/Second> > > Which would became immediately apparent if you programmed in Scheme. One > meter is equal to the wavelength of said magnitude times: Okay, so how is that wavelength defined? If you needed to mark a meter stick, and all you had was the definition of c and the second, how would you do it without measuring anything?
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| From | Marko Rauhamaa <marko@pacujo.net> |
|---|---|
| Date | 2016-07-18 21:58 +0300 |
| Subject | Re: What exactly is "exact" (was Clean Singleton Docstrings) |
| Message-ID | <87wpkircxc.fsf@elektro.pacujo.net> |
| In reply to | #111612 |
Ian Kelly <ian.g.kelly@gmail.com>: > Okay, so how is that wavelength defined? > > If you needed to mark a meter stick, and all you had was the > definition of c and the second, how would you do it without measuring > anything? I wouldn't be measuring a meter stick. To measure, say, the height of a desk, I would bring in some caesium and shine its radiation from the desk level down to the floor. By counting the ebbs and flows of the radiation as it leaves the nozzle and strikes the wooden floor I make the approximage height measurement. However, I know *exactly* how long a meter is without making a measurement. Marko
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| From | Rustom Mody <rustompmody@gmail.com> |
|---|---|
| Date | 2016-07-18 17:36 -0700 |
| Subject | Re: What exactly is "exact" (was Clean Singleton Docstrings) |
| Message-ID | <bcefc3a5-1e2c-4a25-860e-222dde98772e@googlegroups.com> |
| In reply to | #111613 |
On Tuesday, July 19, 2016 at 12:28:36 AM UTC+5:30, Marko Rauhamaa wrote: > Ian Kelly : > > > Okay, so how is that wavelength defined? > > > > If you needed to mark a meter stick, and all you had was the > > definition of c and the second, how would you do it without measuring > > anything? > > I wouldn't be measuring a meter stick. To measure, say, the height of a > desk, I would bring in some caesium and shine its radiation from the > desk level down to the floor. By counting the ebbs and flows of the > radiation as it leaves the nozzle and strikes the wooden floor I make > the approximage height measurement. > > However, I know *exactly* how long a meter is without making a > measurement. I recollect — school physics textbook so sorry no link — that in the Newton gravitation law f = -GMm/r² there was a discussion about the exponent of r ie 2 And that to some 6 decimal places it had been verified that it was actually 2.000002 I dont remember all the details Just that something so obviously to a layman mathematic/analytic as 2 for a physicist may be something calling for experimental verification ie synthetic/scienceic: http://plato.stanford.edu/entries/analytic-synthetic/
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| From | Steven D'Aprano <steve@pearwood.info> |
|---|---|
| Date | 2016-07-19 13:16 +1000 |
| Subject | Re: What exactly is "exact" (was Clean Singleton Docstrings) |
| Message-ID | <578d9b91$0$22140$c3e8da3$5496439d@news.astraweb.com> |
| In reply to | #111619 |
On Tue, 19 Jul 2016 10:36 am, Rustom Mody wrote: > I recollect — school physics textbook so sorry no link — > that in the Newton gravitation law > f = -GMm/r² > > there was a discussion about the exponent of r ie 2 > And that to some 6 decimal places it had been verified that it was > actually 2.000002 Because gravitational forces are so weak, it is very difficult to experimentally distinguish (say) an exponent of 1.999999 from 2.000002 from 2 exactly. Most physicists would say that an experimental result of 2.000002 is pretty good confirmation that the theoretical power of 2 is correct. Only a very few would think that the experiment was evidence that both Newtonian and Einsteinian gravitational theory is incorrect. (Newton, for obvious reasons; but also general relativity, since Newton's law can be derived from the "low mass/large distance" case of general relativity.) But it's an interesting hypothetical: what if the power wasn't 2 exactly? -- Steven “Cheer up,” they said, “things could be worse.” So I cheered up, and sure enough, things got worse.
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| From | Rustom Mody <rustompmody@gmail.com> |
|---|---|
| Date | 2016-07-18 20:26 -0700 |
| Subject | Re: What exactly is "exact" (was Clean Singleton Docstrings) |
| Message-ID | <05d3a70a-865f-416a-9915-447c475ee67c@googlegroups.com> |
| In reply to | #111623 |
On Tuesday, July 19, 2016 at 8:46:44 AM UTC+5:30, Steven D'Aprano wrote: > On Tue, 19 Jul 2016 10:36 am, Rustom Mody wrote: > > > I recollect — school physics textbook so sorry no link — > > that in the Newton gravitation law > > f = -GMm/r² > > > > there was a discussion about the exponent of r ie 2 > > And that to some 6 decimal places it had been verified that it was > > actually 2.000002 > > Because gravitational forces are so weak, it is very difficult to > experimentally distinguish (say) an exponent of 1.999999 from 2.000002 from > 2 exactly. > > Most physicists would say that an experimental result of 2.000002 is pretty > good confirmation that the theoretical power of 2 is correct. Only a very > few would think that the experiment was evidence that both Newtonian and > Einsteinian gravitational theory is incorrect. Yes this was — if memory is right — the conclusion, viz.: Experimentally it looks like 2.000002 (or whatever) This is as good as we can measure So concluding its 2 seems to be reasonable with that 0.000002 relegated to experimental error Nevertheless my main point was that such a math (aka analytic to a layman) looking entity like 2, may for a physicist be a quantity for synthetic verification > > (Newton, for obvious reasons; but also general relativity, since Newton's > law can be derived from the "low mass/large distance" case of general > relativity.) > > But it's an interesting hypothetical: what if the power wasn't 2 exactly? May be related to the margin of error for G being quite high
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| From | Gene Heskett <gheskett@shentel.net> |
|---|---|
| Date | 2016-07-19 01:22 -0400 |
| Subject | Re: What exactly is "exact" (was Clean Singleton Docstrings) |
| Message-ID | <mailman.88.1468930030.2307.python-list@python.org> |
| In reply to | #111623 |
On Monday 18 July 2016 23:16:32 Steven D'Aprano wrote: > On Tue, 19 Jul 2016 10:36 am, Rustom Mody wrote: > > I recollect — school physics textbook so sorry no link — > > that in the Newton gravitation law > > f = -GMm/r² > > > > there was a discussion about the exponent of r ie 2 > > And that to some 6 decimal places it had been verified that it was > > actually 2.000002 > > Because gravitational forces are so weak, it is very difficult to > experimentally distinguish (say) an exponent of 1.999999 from 2.000002 > from 2 exactly. > > Most physicists would say that an experimental result of 2.000002 is > pretty good confirmation that the theoretical power of 2 is correct. > Only a very few would think that the experiment was evidence that both > Newtonian and Einsteinian gravitational theory is incorrect. > > (Newton, for obvious reasons; but also general relativity, since > Newton's law can be derived from the "low mass/large distance" case of > general relativity.) > > But it's an interesting hypothetical: what if the power wasn't 2 > exactly? > I do not believe it is. The theory of relativity says that the faster you are going, the more massive you become. Ergo the rate of the acceleration will decrease as the mass builds up. But the speeds most of us deal with are so close to at rest that we do not realize in the everyday world around us, that this does apply at the speeds you throw that ball while juggling 3 of them. The effect is quite minimal at our everyday speeds, but there is not a set point where it kicks in, its always there. Its just that the difference at everyday speeds, is likely a few hundred digits to the right of the decimal point. Now, trade those 1 lb balls in on a few quintillion electrons, enough to account for 5.3 amps of current thru a klystron amplifier tube, and the acceleration voltage speeding the electrons along is 20,000 volts. That beam of electrons is trucking right along at a measurable fraction of c speed. Its also dumping something more than 100KW into the cooling water flowing thru the bottom of the tube where the beam lands and is absorbed. This amplifier does not operate by varying the current like a normal vacuum tube, it constant current. It is a capacitatively driven tube, and the power comes back out by being capacitatively coupled from the electron beam. How many of you can remember the audio buzz in the UHF channels tv sound 20 years ago? So I am going to tell you how that buzz became part of the UHF landscape for so many years, so bear with me as I have a story to tell. This klystron amplifier, a new one of which was north of $125,000 in the 1970's when I learned about them, is a long tube, around 5 feet long with alternating sections of copper tubeing and ceramic insulators separating the copper sections. Typically 4 ceramic sections, each of which was sealed to a section of copper equiped with contact rings on each end of the copper sections. A tunable box cavity connected the copper sections together, bridging the ceramic spacer, so that when the tube was "dressed" with these cavity's, and lowered into its focusing magnet, (2200 lbs) you could feed about 1 watt of signal into the top cavity, which either retarded the velocity of the beam slightly, or accellerated it a bit. The beam then passed out of that cavity and on into the next one, tuned a couple megahertz lower, then passed thru the third cavity normally tuned about 4.2 megahertz higher. Each cavity it passed thru reinforced this small velocity change until one could visualize the electrons traveling in little balls by the time it enters the last cavity, and this cavity has a coupling loop to extract the amplified signal, 30 kilowatts of it, all because that last cavity is ringing like a bell because of the capacitative coupling between these bunched up electrons and the cavity. The buzz that was so annoying is directly related to the relativistic effects being modified by the video signal. The electrons gain more mass as they speed up, so the speed up does not match the slowdown because they lose mass thereby slowing more, so the net effect is that the tube gets longer at the high power levels of the synch signal, inventing an FM signal that is not there in the drive. Then, since most tv transmitters before digital were actually two transmitters, one for the video, and one for the audio, and the audio ran at a constant power level since it was an FM signal, so the aural was not similarly effected. The old tv's also used the difference frequency, here in the US of 4.5 megahertz as their aural detection system. So this FM component to the visual became mixed with the unaffected audio, injecting this darned buzz into the audio IN your tv. And relativity, in the form of e=mv2 was the culprit. Not even the FCC had that figured out. I had that pointed out to me by a blown water pump breaker, and the lack of cooling water blew the bottom out of the collector bucket on the visual tube. About 50 milliseconds after the pump went locked rotor from the phase failure. After replacing the breaker, I wheeled the aural tube out of its cubicle and put it into the visual transmitter and tuned it up for picture service, old tube, got about 80% power out of it. Then I rigged a cable of aural drive over to the visual and fed about 100 milliwatts of aural drive just to get back on the air while Varian was building me a new klystron which takes several weeks. At home that night, checking to see if the viewers might notice, the pix looked ok but something told me to crank up the sound. Zero buzz, because both signals were being amplified in the same tube, and subjected to identical amounts of this distortion, there was no difference to be detected in the tv itself. The distortion was absolutely in lock step and totally inaudible to the tv's. With both tubes running normally, that buzz was only down about 53db at best. So relativity applies, even to the baseball being thrown by a little leager. We just do not have the precision to measure it when the effect is hundreds of digits to the right of the decimal point. Cheers, Gene Heskett -- "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) Genes Web page <http://geneslinuxbox.net:6309/gene>
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| From | Lawrence D’Oliveiro <lawrencedo99@gmail.com> |
|---|---|
| Date | 2016-07-19 10:46 -0700 |
| Subject | Re: What exactly is "exact" (was Clean Singleton Docstrings) |
| Message-ID | <f8fe07cb-ad95-4512-adfc-ee7b6caac9e0@googlegroups.com> |
| In reply to | #111638 |
On Wednesday, July 20, 2016 at 12:07:25 AM UTC+12, Gene Heskett wrote: > This klystron amplifier, a new one of which was north of $125,000 in the > 1970's when I learned about them, is a long tube, around 5 feet long > with alternating sections of copper tubeing and ceramic insulators > separating the copper sections. Typically 4 ceramic sections, each of > which was sealed to a section of copper equiped with contact rings on > each end of the copper sections. A tunable box cavity connected the > copper sections together, bridging the ceramic spacer, so that when the > tube was "dressed" with these cavity's, and lowered into its focusing > magnet, (2200 lbs) you could feed about 1 watt of signal into the top > cavity... What is this “watt” of which you speak? How much is that in foot-poundals per second?
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| From | Gene Heskett <gheskett@shentel.net> |
|---|---|
| Date | 2016-07-19 16:35 -0400 |
| Subject | Re: What exactly is "exact" (was Clean Singleton Docstrings) |
| Message-ID | <mailman.0.1468963061.2281.python-list@python.org> |
| In reply to | #111642 |
On Tuesday 19 July 2016 13:46:37 Lawrence D’Oliveiro wrote: > On Wednesday, July 20, 2016 at 12:07:25 AM UTC+12, Gene Heskett wrote: > > This klystron amplifier, a new one of which was north of $125,000 in > > the 1970's when I learned about them, is a long tube, around 5 feet > > long with alternating sections of copper tubeing and ceramic > > insulators separating the copper sections. Typically 4 ceramic > > sections, each of which was sealed to a section of copper equiped > > with contact rings on each end of the copper sections. A tunable box > > cavity connected the copper sections together, bridging the ceramic > > spacer, so that when the tube was "dressed" with these cavity's, and > > lowered into its focusing magnet, (2200 lbs) you could feed about 1 > > watt of signal into the top cavity... > > What is this “watt” of which you speak? How much is that in > foot-poundals per second? A unit of electrical power, simplified to 1 volt at 1 amp = 1 watt when that currant is passed thru a 1 ohm resistor. But since the majority of radio frequency stuff is designed for a characteristic impedance of 50 ohms, then the currant is 20 milliamps while the voltage rises to 50 volts. And I am not familiar with this foot-poundals per second that you question about, but just from the wording I'd say it is a fifty dollar way to say horsepower. Which is defined in the area of exerting a force to a 440 pound weight, sufficient to lift that weight one foot in one second. Thats for an average horse. I was once in the seat of a stuck in the mud clear above the drawbar of a 1930's Case LA farm tractor. About 8500 lbs. Daddy whistled up King & Colonial, a pair of perches that between them weighted a hundred or so above the 4000 pound mark on the dial at the elevator. :) He also dug out a brace & bit to make a new double-tree out of a 7 foot length of well seasoned Iowa oak cut full native size of 2" thick by 12" wide. And despite the rationing in effect at the end of WW-II when this took place, found a lb of sugar cubes for his overall pocket. Harnessing up the perches, he hooked the traces to this new double-tree, and cleviced a 75 foot length of 1/2" chain to it. He brought them down to where the tractor could be reached from fairly dry ground, drug that chain down and hooked it to the back frame of the 4 bottom 16" plow I was pulling at the time, pulled the hitch pin after digging down to it, waded back the the perches and took a place where he could grab the bridals and made tsk tsk noises. Pulling the plow was done so it would not be in the way. Lead them back and brought the chain back & hooked it to the drawbar. Walking back to the horses he had a small handfull of sugar cubes in each hand and gave it to them. Then grasping the bridals again, a push forward with the tsk tsk. Then a whoa. They had found they were stuck and would need to put some real pull on that chain the next time, which they did, digging a trench under their bellies for about 10 feet when daddy said whoa again. The tractor had moved. So he gave me instructions to put it in reverse and to be ready to slam the clutch lever home the next time it moved. After a breather, wash, rinse and repeat and the tractor was back on dry ground. At peak pull, that 75 feet of 1/2" log chain was up in the air about 6" in the middle. Now if any of you know how to convert that mid-sag amount, the pull on the chain can be deduced, its called the intercept point method. My guess is that that 4100 lbs of horseflesh were peaking at 10,000 lbs on the far end of that chain. They of course can't do it for very long, 10 seconds perhaps, but by then I was loose and all they were dragging was the chain. The horses got the rest of that pound of sugar cubes. Those were the two most gentle giants I have ever lived around. WW-II ended just a couple months later with V-J day. Cheers, Gene Heskett -- "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) Genes Web page <http://geneslinuxbox.net:6309/gene>
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| From | Marko Rauhamaa <marko@pacujo.net> |
|---|---|
| Date | 2016-07-20 01:17 +0300 |
| Subject | Re: What exactly is "exact" (was Clean Singleton Docstrings) |
| Message-ID | <87lh0xqnmi.fsf@elektro.pacujo.net> |
| In reply to | #111644 |
Gene Heskett <gheskett@shentel.net>: > On Tuesday 19 July 2016 13:46:37 Lawrence D’Oliveiro wrote: >> What is this “watt” of which you speak? > > A unit of electrical power, simplified to 1 volt at 1 amp = 1 watt > when that currant is passed thru a 1 ohm resistor. But since the > majority of radio frequency stuff is designed for a characteristic > impedance of 50 ohms, then the currant is 20 milliamps while the > voltage rises to 50 volts. Where I live, it is mandatory for stores to display not only prices but also prices per unit. Unfortunately, the "unit" for batteries is a piece. Thus, it is not possible to make price comparisons between different battery brands. I'd love it if batteries were priced per joule, or even per kilowatt-hour. According to <URL: http://www.allaboutbatteries.com/Energy-tables.html>, an alkaline AA battery holds 0.00260 kWh. Amazon is selling the Duracell brand at USD 18.38/34-pack, or at about USD 200/kWh. Marko
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| From | Random832 <random832@fastmail.com> |
|---|---|
| Date | 2016-07-19 23:15 -0400 |
| Subject | Re: What exactly is "exact" (was Clean Singleton Docstrings) |
| Message-ID | <mailman.3.1468984532.2281.python-list@python.org> |
| In reply to | #111648 |
On Tue, Jul 19, 2016, at 18:17, Marko Rauhamaa wrote: > I'd love it if batteries were priced per joule, or even per > kilowatt-hour. Typically their capacity is labeled in amp-hours. You have to know your devices to know if the voltage difference between different battery types (Which ranges from 1.2 to 1.7 for nominal-1.5 AAA/AA/C/D cells, and may be lower under load) is significant or not, and in what direction. A lower-voltage battery in an incandescent flashlight will last longer but not be as bright. No idea how it shakes out for LEDs, motors, or complex electronics. Some devices may not be operable at all below a certain voltage, and of course the voltage reduces over time as the battery is drained. There are just too many variables, and even the nominal amp-hour rating assumes a certain discharge rate. And of course, for rechargeable batteries there are even more variables; but there what you're buying isn't power.
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| From | Marko Rauhamaa <marko@pacujo.net> |
|---|---|
| Date | 2016-07-20 10:16 +0300 |
| Subject | Re: What exactly is "exact" (was Clean Singleton Docstrings) |
| Message-ID | <87zipcpymy.fsf@elektro.pacujo.net> |
| In reply to | #111655 |
Random832 <random832@fastmail.com>: > On Tue, Jul 19, 2016, at 18:17, Marko Rauhamaa wrote: >> I'd love it if batteries were priced per joule, or even per >> kilowatt-hour. > > Typically their capacity is labeled in amp-hours. Did you really see that labeled on the (nonrechargeable AA) battery? > You have to know your devices to know if the voltage difference > between different battery types (Which ranges from 1.2 to 1.7 for > nominal-1.5 AAA/AA/C/D cells, and may be lower under load) is > significant or not, and in what direction. Well, your amp hours will be shittier with a lower voltage. That's why reporting joules would be more honest. Marko
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| From | Random832 <random832@fastmail.com> |
|---|---|
| Date | 2016-07-20 10:00 -0400 |
| Subject | Re: What exactly is "exact" (was Clean Singleton Docstrings) |
| Message-ID | <mailman.5.1469023239.22221.python-list@python.org> |
| In reply to | #111662 |
On Wed, Jul 20, 2016, at 03:16, Marko Rauhamaa wrote: > Random832 <random832@fastmail.com>: > > Typically their capacity is labeled in amp-hours. > > Did you really see that labeled on the (nonrechargeable AA) battery? Sorry, I must have imagined that. Anyway, my point was that the reality is too complicated to easily assign a number to - that they don't even try supports that. Duracell's datasheets don't even have a single number, just a bunch of line graphs. > > You have to know your devices to know if the voltage difference > > between different battery types (Which ranges from 1.2 to 1.7 for > > nominal-1.5 AAA/AA/C/D cells, and may be lower under load) is > > significant or not, and in what direction. > > Well, your amp hours will be shittier with a lower voltage. Define "shittier". An incandescent flashlight (which consumes less power at lower voltage) will last longer, but won't be as bright. If it's still acceptably bright, that's not worse. > That's why > reporting joules would be more honest. And *my* point is that the number of joules depends on how the battery is used. And different types of batteries are optimized for different applications.
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| From | Gregory Ewing <greg.ewing@canterbury.ac.nz> |
|---|---|
| Date | 2016-07-21 10:46 +1200 |
| Subject | Re: What exactly is "exact" (was Clean Singleton Docstrings) |
| Message-ID | <dvadb4FnuqlU1@mid.individual.net> |
| In reply to | #111673 |
Random832 wrote: >>Well, your amp hours will be shittier with a lower voltage. > > Define "shittier". An incandescent flashlight (which consumes less power > at lower voltage) will last longer, but won't be as bright. If it's > still acceptably bright, that's not worse. I think the point is that the cell will deliver (at most) the same number of amp-hours at high load as low load, but if the voltage is lower, those amp-hours will represent less energy delivered to the load. An amp-hour that doesn't give you as much energy as you were expecting could be described as "shitty". :-) On top of that, the cell might deliver less amp-hours at high load, for bonus shittiness. -- Greg
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| From | Ian Kelly <ian.g.kelly@gmail.com> |
|---|---|
| Date | 2016-07-19 16:27 -0600 |
| Subject | Re: What exactly is "exact" (was Clean Singleton Docstrings) |
| Message-ID | <mailman.2.1468967272.2281.python-list@python.org> |
| In reply to | #111642 |
On Tue, Jul 19, 2016 at 2:35 PM, Gene Heskett <gheskett@shentel.net> wrote: > And I am not familiar with this foot-poundals per second that you > question about, but just from the wording I'd say it is a fifty dollar > way to say horsepower. https://en.wikipedia.org/wiki/Foot-poundal > Which is defined in the area of exerting a force > to a 440 pound weight, sufficient to lift that weight one foot in one > second. 1 (imperial) horsepower is 550 (not 440) foot-pounds per second. A foot-pound is the energy transferred by exerting a 1-pound force through a displacement of 1 foot. A pound is the force needed to accelerate 1 pound-mass at 32.174 ft/s**2 (the acceleration of gravity). A poundal in contrast is the force needed to accelerate 1 pound-mass at 1 ft/s**2. A foot-poundal therefore is the energy transferred by exerting a 1-poundal force through a displacement of 1 foot. A foot-poundal is thus (approximately) 1/32.174 of a foot-pound. Multiplying it out, 1 horsepower is approximately 17695.7 foot-poundals per second. Ah, the machinations that users of imperial units have to endure.
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| From | Marko Rauhamaa <marko@pacujo.net> |
|---|---|
| Date | 2016-07-20 02:09 +0300 |
| Subject | Re: What exactly is "exact" (was Clean Singleton Docstrings) |
| Message-ID | <87bn1tql6h.fsf@elektro.pacujo.net> |
| In reply to | #111649 |
Ian Kelly <ian.g.kelly@gmail.com>: > Ah, the machinations that users of imperial units have to endure. Europeans often mistakenly believe that Americans haven't yet adopted the SI units. They have: - the length of a ski is measured in centimeters - the width of film and the diameter of a gun barrel are measured in millimeters - the wavelength of visible light is measured in nanometers - the volume of a soda bottle is measured in liters - a quantity of confiscated narcotics is measured in kilograms - daily allowance of a vitamin is measured in milligrams - the pitch of a note is measured in hertz - a short timespan is measured in seconds So the problem Europeans have with the situation is *not* the lack of adoption of new units. Rather, it is the refusal of giving up the traditional units. The Anglo-American culture is notorious for its eagerness to absorb foreign influences. What it abhors is reductionism. There is always room for more words, ideas, mores, inventions, but nothing is ever deprecated with a simple edict. Marko
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| From | alister <alister.ware@ntlworld.com> |
|---|---|
| Date | 2016-07-20 13:24 +0000 |
| Subject | Re: What exactly is "exact" (was Clean Singleton Docstrings) |
| Message-ID | <zYKjz.875181$GD.473331@fx33.am4> |
| In reply to | #111651 |
On Wed, 20 Jul 2016 02:09:58 +0300, Marko Rauhamaa wrote: > Ian Kelly <ian.g.kelly@gmail.com>: > >> Ah, the machinations that users of imperial units have to endure. > > Europeans often mistakenly believe that Americans haven't yet adopted > the SI units. They have: > > - the length of a ski is measured in centimeters > > - the width of film and the diameter of a gun barrel are measured in > millimeters > > - the wavelength of visible light is measured in nanometers > > - the volume of a soda bottle is measured in liters > > - a quantity of confiscated narcotics is measured in kilograms > > - daily allowance of a vitamin is measured in milligrams > > - the pitch of a note is measured in hertz > > - a short timespan is measured in seconds > > > So the problem Europeans have with the situation is *not* the lack of > adoption of new units. Rather, it is the refusal of giving up the > traditional units. > > The Anglo-American culture is notorious for its eagerness to absorb > foreign influences. What it abhors is reductionism. There is always room > for more words, ideas, mores, inventions, but nothing is ever deprecated > with a simple edict. > > > Marko One of my biggest questions since the Brexit vote is can we g back to using imperial weights & measures (please). -- Egotist: A person of low taste, more interested in himself than in me. -- Ambrose Bierce
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| From | Steven D'Aprano <steve@pearwood.info> |
|---|---|
| Date | 2016-07-21 14:04 +1000 |
| Subject | Re: What exactly is "exact" (was Clean Singleton Docstrings) |
| Message-ID | <579049be$0$1591$c3e8da3$5496439d@news.astraweb.com> |
| In reply to | #111671 |
On Wed, 20 Jul 2016 11:24 pm, alister wrote: > One of my biggest questions since the Brexit vote is can we g back to > using imperial weights & measures (please). I suppose you might as well -- there's no more empire, no more jobs or houses, and once the financial traders leave London there'll be no more money. When Scotland and Northern Ireland leaves there'll be no more United Kingdom either, and then you and the Welsh can sit around all day trying to remember how many cubic chains in a hogshead and the number of pints to a firkin, and blaming the perfidious French and cabbage-eating Huns for kicking you out of the EU against your will. England Prevails! -- Steven “Cheer up,” they said, “things could be worse.” So I cheered up, and sure enough, things got worse.
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| From | Lawrence D’Oliveiro <lawrencedo99@gmail.com> |
|---|---|
| Date | 2016-07-19 17:01 -0700 |
| Subject | Re: What exactly is "exact" (was Clean Singleton Docstrings) |
| Message-ID | <5d5b4214-71c7-4096-a297-a9f9f0247646@googlegroups.com> |
| In reply to | #111649 |
On Wednesday, July 20, 2016 at 10:28:04 AM UTC+12, Ian wrote: > Ah, the machinations that users of imperial units have to endure. Deep in some people’s hearts, the Mars Climate Orbiter still sails...
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