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Groups > comp.lang.java.programmer > #25115
| From | Daniel Pitts <newsgroup.nospam@virtualinfinity.net> |
|---|---|
| Newsgroups | comp.lang.java.programmer |
| Subject | Re: Autoboxing and Performance ? |
| References | (5 earlier) <b7lk0hFpbj9U1@mid.dfncis.de> <5csRt.197906$jW3.50636@fx23.iad> <kv5p7j$30v$1@dont-email.me> <units-20130822220059@ram.dialup.fu-berlin.de> <kv5v87$1og$1@dont-email.me> |
| Message-ID | <kyvRt.176811$Z84.113359@fx29.iad> (permalink) |
| Date | 2013-08-22 14:39 -0700 |
On 8/22/13 2:19 PM, Martin Gregorie wrote: > On Thu, 22 Aug 2013 20:19:58 +0000, Stefan Ram wrote: > >> Moreover, a lenght (in physics) /does not have/ a unit! >> > As a chemistry graduate I disagree quite strongly with that. Its quite > impossible to calculate anything without knowing the units the givens > were measured in. I seem to recall a certain NASA Mars probe failing > because the units used to measure fuel remaining were unstated. As a > result somebody calculated burns wrongly by confusing lbs and kg, causing > the probe to run out of fuel and miss Mars entirely. > >> For example, there is a certain distance from the sun to the Procyon, >> what is the unit of that lenght? As a physical value, it has no unit! >> Only when one wants to write it down, one has to choose a certain unit >> system and number system, and one can choose every unit system one >> likes. This is an artefact of our notation, not a property of the >> length. >> > If you don't know the units the measurement was made in, its a > meaningless number that can't be used to calculate a valid result any > more than you can add "not very far" to "a huge distance" and get a > measurable distance. > > To Stefan's point, the distance itself isn't actually a number with a unit. It isn't a number at all but a concrete distance. To *represent* that distance, you need to know two things about it, a number and a unit. Unit's themselves are concrete values, which can be multiplied by a scalar to arrive at other concrete values. In other words, to measure something, you compare it to multiples of some other something. The number of multiples is your scalar, and the "some other something" is the unit. So, the unit needn't be recorded along with the number, as long as the unit and number are tied together somehow. A Length class is the perfect place to do that tying. A Length class can store the value as a number, and ensure that the units consistent. The units may be implicit or explicit. Implicit units meaning the Length class always uses the same units to store the value, and only converts when asked for different units. Explicit units means the Length class stores a Unit property, which handles the conversion.
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Autoboxing and Performance ? Peter Olcott <OCR4Screen> - 2013-08-20 05:15 -0500
Re: Autoboxing and Performance ? Joerg Meier <joergmmeier@arcor.de> - 2013-08-20 12:20 +0200
Re: Autoboxing and Performance ? Peter Olcott <OCR4Screen> - 2013-08-20 05:33 -0500
Re: Autoboxing and Performance ? Andreas Leitgeb <avl@gamma.logic.tuwien.ac.at> - 2013-08-20 10:43 +0000
Re: Autoboxing and Performance ? Peter Olcott <OCR4Screen> - 2013-08-20 06:04 -0500
Re: Autoboxing and Performance ? Eric Sosman <esosman@comcast-dot-net.invalid> - 2013-08-20 08:08 -0400
Re: Autoboxing and Performance ? Arne Vajhøj <arne@vajhoej.dk> - 2013-08-20 20:15 -0400
Re: Autoboxing and Performance ? Arne Vajhøj <arne@vajhoej.dk> - 2013-08-20 20:12 -0400
Re: Autoboxing and Performance ? Sven Köhler <remove-sven.koehler@gmail.com> - 2013-08-21 03:52 +0300
Re: Autoboxing and Performance ? Sebastian <news@seyweiler.dyndns.org> - 2013-08-21 07:27 +0200
Re: Autoboxing and Performance ? Arne Vajhøj <arne@vajhoej.dk> - 2013-08-21 18:43 -0400
Re: Autoboxing and Performance ? Sven Köhler <remove-sven.koehler@gmail.com> - 2013-08-22 08:08 +0300
Re: Autoboxing and Performance ? Sven Köhler <remove-sven.koehler@gmail.com> - 2013-08-22 07:56 +0300
Re: Autoboxing and Performance ? Daniel Pitts <newsgroup.nospam@virtualinfinity.net> - 2013-08-22 10:51 -0700
Re: Autoboxing and Performance ? Martin Gregorie <martin@address-in-sig.invalid> - 2013-08-22 19:36 +0000
Re: Autoboxing and Performance ? Daniel Pitts <newsgroup.nospam@virtualinfinity.net> - 2013-08-22 13:01 -0700
Re: Autoboxing and Performance ? Martin Gregorie <martin@address-in-sig.invalid> - 2013-08-22 21:19 +0000
Re: Autoboxing and Performance ? Daniel Pitts <newsgroup.nospam@virtualinfinity.net> - 2013-08-22 14:39 -0700
Re: Autoboxing and Performance ? markspace <markspace@nospam.nospam> - 2013-08-22 19:50 -0700
Re: Autoboxing and Performance ? Martin Gregorie <martin@address-in-sig.invalid> - 2013-08-23 23:16 +0000
Re: Autoboxing and Performance ? Sven Köhler <remove-sven.koehler@gmail.com> - 2013-08-24 17:20 +0300
Re: Autoboxing and Performance ? Lew <lewbloch@gmail.com> - 2013-08-23 11:08 -0700
Re: Autoboxing and Performance ? Joerg Meier <joergmmeier@arcor.de> - 2013-08-23 22:52 +0200
Re: Autoboxing and Performance ? Jim Gibson <jimsgibson@gmail.com> - 2013-08-23 16:38 -0700
Re: Autoboxing and Performance ? "John B. Matthews" <nospam@nospam.invalid> - 2013-08-23 06:17 -0400
Re: Autoboxing and Performance ? Jeff Higgins <jeff@invalid.invalid> - 2013-08-23 17:25 -0400
Re: Autoboxing and Performance ? Jeff Higgins <jeff@invalid.invalid> - 2013-08-25 18:34 -0400
Re: Autoboxing and Performance ? Jeff Higgins <jeff@invalid.invalid> - 2013-08-28 10:52 -0400
Re: Autoboxing and Performance ? Martin Gregorie <martin@address-in-sig.invalid> - 2013-08-23 23:37 +0000
Re: Autoboxing and Performance ? Robert Klemme <shortcutter@googlemail.com> - 2013-08-26 19:33 +0200
Re: Autoboxing and Performance ? Sven Köhler <remove-sven.koehler@gmail.com> - 2013-08-29 10:09 +0300
Re: Autoboxing and Performance ? Jan Burse <janburse@fastmail.fm> - 2013-08-29 14:14 +0200
Re: Autoboxing and Performance ? Arved Sandstrom <asandstrom2@eastlink.ca> - 2013-08-29 21:28 -0300
Re: Autoboxing and Performance ? Jan Burse <janburse@fastmail.fm> - 2013-08-20 20:03 +0200
Re: Autoboxing and Performance ? Lew <lewbloch@gmail.com> - 2013-08-20 16:23 -0700
Re: Autoboxing and Performance ? Jan Burse <janburse@fastmail.fm> - 2013-08-21 11:51 +0200
Re: Autoboxing and Performance ? Lew <lewbloch@gmail.com> - 2013-08-21 08:39 -0700
Re: Autoboxing and Performance ? lipska the kat <"nospam at neversurrender dot co dot uk"> - 2013-08-21 16:51 +0100
Re: Autoboxing and Performance ? Arne Vajhøj <arne@vajhoej.dk> - 2013-08-21 19:19 -0400
Re: Autoboxing and Performance ? Jan Burse <janburse@fastmail.fm> - 2013-08-22 09:49 +0200
Re: Autoboxing and Performance ? Jan Burse <janburse@fastmail.fm> - 2013-08-21 11:54 +0200
Re: Autoboxing and Performance ? Arne Vajhøj <arne@vajhoej.dk> - 2013-08-20 20:06 -0400
Re: Autoboxing and Performance ? Eric Sosman <esosman@comcast-dot-net.invalid> - 2013-08-20 21:19 -0400
Re: Autoboxing and Performance ? Joerg Meier <joergmmeier@arcor.de> - 2013-08-21 10:05 +0200
Re: Autoboxing and Performance ? Eric Sosman <esosman@comcast-dot-net.invalid> - 2013-08-21 07:19 -0400
Re: Autoboxing and Performance ? Joerg Meier <joergmmeier@arcor.de> - 2013-08-22 00:18 +0200
Re: Autoboxing and Performance ? Eric Sosman <esosman@comcast-dot-net.invalid> - 2013-08-21 19:58 -0400
Re: Autoboxing and Performance ? Lew <lewbloch@gmail.com> - 2013-08-21 08:36 -0700
Re: Autoboxing and Performance ? taqmcg@gmail.com - 2013-08-21 09:37 -0700
Re: Autoboxing and Performance ? Joshua Cranmer 🐧 <Pidgeot18@verizon.invalid> - 2013-08-20 23:28 -0500
Re: Autoboxing and Performance ? lipska the kat <"nospam at neversurrender dot co dot uk"> - 2013-08-21 10:09 +0100
Re: Autoboxing and Performance ? Arne Vajhøj <arne@vajhoej.dk> - 2013-08-21 19:04 -0400
Re: Autoboxing and Performance ? Arivald <NOSPAMarivald@interia.pl> - 2013-08-22 07:39 +0200
Re: Autoboxing and Performance ? Arved Sandstrom <asandstrom2@eastlink.ca> - 2013-08-29 01:42 -0300
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