Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]
Groups > comp.lang.python > #111297
| From | Chris Angelico <rosuav@gmail.com> |
|---|---|
| Newsgroups | comp.lang.python |
| Subject | Re: What is precision of a number representation? (was: Curious Omission In New-Style Formats) |
| Date | 2016-07-12 07:51 +1000 |
| Message-ID | <mailman.197.1468273886.2295.python-list@python.org> (permalink) |
| References | (5 earlier) <mailman.180.1468249505.2295.python-list@python.org> <5783c91e$0$1622$c3e8da3$5496439d@news.astraweb.com> <5783D63F.5040307@stoneleaf.us> <8560sbvqqd.fsf_-_@benfinney.id.au> <CAPTjJmqL=1cxkCK+PAdTK7Cky95B_QoUNTZkgBxKDcJ9XGf+Bw@mail.gmail.com> |
On Tue, Jul 12, 2016 at 6:56 AM, Ben Finney <ben+python@benfinney.id.au> wrote: > Precision is not a property of the number. It is a property of the > *representation* of that number. > > The representation “1×10²” has a precision of one digit. > The representation “100” has a precision of three digits. > The representation “00100” has a precision of five digits. > The representation “100.00” also has a precision of five digits. > > Those can all represent the same number; or maybe some of them represent > “one hundred” and others represent “one hundred and a millionth”. > Yep. Precision is also a property of a measurement, the same way that a unit is. If I pace out the length of the main corridor in my house, I might come up with a result of thirty meters. The number is "30"; the unit is "meters", the precision is two significant digits, and the accuracy depends on how good I am at pacing distance. This is why it's important to be able to record precisions of arbitrary numbers. If I then measure the width of this corridor with a laser, I could get an extremely precise answer - say, 2,147 millimeters, with a precision of four significant digits, and excellent accuracy. But if I multiply those numbers together to establish the floor area of the corridor, the result does NOT have four significant figures. It would be 64 square meters (not 64.41), and the accuracy would be pretty low (effectively, the *in*accuracies of both measurements get combined). But on the other hand, if you want to know whether your new fridge will fit, you could measure it with the same laser and come up with a figure of 1,973 mm (four sig fig), which would mean your clearance is 174mm (four sig fig). How do you record this? Is it 174.0? 0174? "174 with four significant figures"? ChrisA
Back to comp.lang.python | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread
Curious Omission In New-Style Formats Lawrence D’Oliveiro <lawrencedo99@gmail.com> - 2016-07-09 22:54 -0700
Re: Curious Omission In New-Style Formats Ian Kelly <ian.g.kelly@gmail.com> - 2016-07-10 01:21 -0600
Re: Curious Omission In New-Style Formats Lawrence D’Oliveiro <lawrencedo99@gmail.com> - 2016-07-10 17:34 -0700
Re: Curious Omission In New-Style Formats Ian Kelly <ian.g.kelly@gmail.com> - 2016-07-11 09:04 -0600
Re: Curious Omission In New-Style Formats Steven D'Aprano <steve@pearwood.info> - 2016-07-12 02:28 +1000
Re: Curious Omission In New-Style Formats Ethan Furman <ethan@stoneleaf.us> - 2016-07-11 10:24 -0700
Re: Curious Omission In New-Style Formats Gregory Ewing <greg.ewing@canterbury.ac.nz> - 2016-07-12 11:47 +1200
Re: Curious Omission In New-Style Formats Ethan Furman <ethan@stoneleaf.us> - 2016-07-11 17:24 -0700
Re: Curious Omission In New-Style Formats Ian Kelly <ian.g.kelly@gmail.com> - 2016-07-11 19:16 -0600
Re: Curious Omission In New-Style Formats Ian Kelly <ian.g.kelly@gmail.com> - 2016-07-11 12:38 -0600
Re: Curious Omission In New-Style Formats Steven D'Aprano <steve@pearwood.info> - 2016-07-12 13:38 +1000
Re: Curious Omission In New-Style Formats Ian Kelly <ian.g.kelly@gmail.com> - 2016-07-13 00:21 -0600
Re: Curious Omission In New-Style Formats Marko Rauhamaa <marko@pacujo.net> - 2016-07-13 09:57 +0300
Re: Curious Omission In New-Style Formats Lawrence D’Oliveiro <lawrencedo99@gmail.com> - 2016-07-13 00:05 -0700
Re: Curious Omission In New-Style Formats Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2016-07-13 18:49 +1000
Re: Curious Omission In New-Style Formats Antoon Pardon <antoon.pardon@rece.vub.ac.be> - 2016-07-13 16:01 +0200
Re: Curious Omission In New-Style Formats Dennis Lee Bieber <wlfraed@ix.netcom.com> - 2016-07-13 20:04 -0400
Re: Curious Omission In New-Style Formats Lawrence D’Oliveiro <lawrencedo99@gmail.com> - 2016-07-13 15:24 -0700
Re: Curious Omission In New-Style Formats Ian Kelly <ian.g.kelly@gmail.com> - 2016-07-13 18:45 -0600
Re: Curious Omission In New-Style Formats Lawrence D’Oliveiro <lawrencedo99@gmail.com> - 2016-07-13 20:39 -0700
Re: Curious Omission In New-Style Formats Ian Kelly <ian.g.kelly@gmail.com> - 2016-07-13 23:18 -0600
Re: Curious Omission In New-Style Formats Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2016-07-14 17:47 +1000
Re: Curious Omission In New-Style Formats Dennis Lee Bieber <wlfraed@ix.netcom.com> - 2016-07-14 07:34 -0400
Re: Curious Omission In New-Style Formats Ian Kelly <ian.g.kelly@gmail.com> - 2016-07-14 08:30 -0600
Re: Curious Omission In New-Style Formats Marko Rauhamaa <marko@pacujo.net> - 2016-07-14 19:02 +0300
Re: Curious Omission In New-Style Formats Ian Kelly <ian.g.kelly@gmail.com> - 2016-07-14 11:10 -0600
Re: Curious Omission In New-Style Formats Marko Rauhamaa <marko@pacujo.net> - 2016-07-14 20:30 +0300
Re: Curious Omission In New-Style Formats Ian Kelly <ian.g.kelly@gmail.com> - 2016-07-14 18:17 -0600
Re: Curious Omission In New-Style Formats Lawrence D’Oliveiro <lawrencedo99@gmail.com> - 2016-07-14 18:08 -0700
Re: Curious Omission In New-Style Formats Marko Rauhamaa <marko@pacujo.net> - 2016-07-15 09:06 +0300
Re: Curious Omission In New-Style Formats Antoon Pardon <antoon.pardon@rece.vub.ac.be> - 2016-07-15 09:54 +0200
Re: Curious Omission In New-Style Formats Jussi Piitulainen <jussi.piitulainen@helsinki.fi> - 2016-07-15 11:40 +0300
Re: Curious Omission In New-Style Formats Steven D'Aprano <steve@pearwood.info> - 2016-07-15 20:56 +1000
Re: Curious Omission In New-Style Formats Antoon Pardon <antoon.pardon@rece.vub.ac.be> - 2016-07-15 13:44 +0200
Re: Curious Omission In New-Style Formats Jussi Piitulainen <jussi.piitulainen@helsinki.fi> - 2016-07-15 16:38 +0300
Re: Curious Omission In New-Style Formats Antoon Pardon <antoon.pardon@rece.vub.ac.be> - 2016-07-15 16:47 +0200
Re: Curious Omission In New-Style Formats Jussi Piitulainen <jussi.piitulainen@helsinki.fi> - 2016-07-15 16:13 +0300
Re: Curious Omission In New-Style Formats Steven D'Aprano <steve@pearwood.info> - 2016-07-16 01:12 +1000
Re: Curious Omission In New-Style Formats Random832 <random832@fastmail.com> - 2016-07-15 09:39 -0400
Re: Curious Omission In New-Style Formats Antoon Pardon <antoon.pardon@rece.vub.ac.be> - 2016-07-15 16:32 +0200
Re: Curious Omission In New-Style Formats Antoon Pardon <antoon.pardon@rece.vub.ac.be> - 2016-07-15 13:05 +0200
Re: Curious Omission In New-Style Formats Jussi Piitulainen <jussi.piitulainen@helsinki.fi> - 2016-07-15 16:28 +0300
Re: Curious Omission In New-Style Formats Steven D'Aprano <steve@pearwood.info> - 2016-07-16 01:13 +1000
Re: Curious Omission In New-Style Formats Jussi Piitulainen <jussi.piitulainen@helsinki.fi> - 2016-07-15 18:27 +0300
Re: Curious Omission In New-Style Formats Marko Rauhamaa <marko@pacujo.net> - 2016-07-15 12:20 +0300
Re: Curious Omission In New-Style Formats Antoon Pardon <antoon.pardon@rece.vub.ac.be> - 2016-07-15 12:44 +0200
Re: Curious Omission In New-Style Formats Lawrence D’Oliveiro <lawrencedo99@gmail.com> - 2016-07-14 16:26 -0700
Re: Curious Omission In New-Style Formats Robert Kern <robert.kern@gmail.com> - 2016-07-14 16:17 +0100
Re: Curious Omission In New-Style Formats Lawrence D’Oliveiro <lawrencedo99@gmail.com> - 2016-07-15 16:35 -0700
Re: Curious Omission In New-Style Formats Chris Angelico <rosuav@gmail.com> - 2016-07-16 10:57 +1000
Re: Curious Omission In New-Style Formats MRAB <python@mrabarnett.plus.com> - 2016-07-14 01:59 +0100
Re: Curious Omission In New-Style Formats Dennis Lee Bieber <wlfraed@ix.netcom.com> - 2016-07-13 07:46 -0400
Re: Curious Omission In New-Style Formats Jussi Piitulainen <jussi.piitulainen@helsinki.fi> - 2016-07-13 16:04 +0300
Re: Curious Omission In New-Style Formats Chris Angelico <rosuav@gmail.com> - 2016-07-13 23:00 +1000
Re: Curious Omission In New-Style Formats Jussi Piitulainen <jussi.piitulainen@helsinki.fi> - 2016-07-13 16:16 +0300
Re: Curious Omission In New-Style Formats Chris Angelico <rosuav@gmail.com> - 2016-07-13 23:49 +1000
Re: Curious Omission In New-Style Formats Jussi Piitulainen <jussi.piitulainen@helsinki.fi> - 2016-07-13 17:23 +0300
Re: Curious Omission In New-Style Formats Chris Angelico <rosuav@gmail.com> - 2016-07-14 00:28 +1000
Re: Curious Omission In New-Style Formats Terry Reedy <tjreedy@udel.edu> - 2016-07-11 14:54 -0400
Re: Curious Omission In New-Style Formats Ian Kelly <ian.g.kelly@gmail.com> - 2016-07-11 13:27 -0600
Re: Curious Omission In New-Style Formats Michael Torrie <torriem@gmail.com> - 2016-07-11 14:06 -0600
Re: Curious Omission In New-Style Formats Random832 <random832@fastmail.com> - 2016-07-11 16:34 -0400
Re: Curious Omission In New-Style Formats Terry Reedy <tjreedy@udel.edu> - 2016-07-11 16:52 -0400
What is precision of a number representation? (was: Curious Omission In New-Style Formats) Ben Finney <ben+python@benfinney.id.au> - 2016-07-12 06:56 +1000
Re: What is precision of a number representation? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2016-07-11 23:28 +0100
Re: What is precision of a number representation? Ethan Furman <ethan@stoneleaf.us> - 2016-07-11 14:22 -0700
Re: What is precision of a number representation? (was: Curious Omission In New-Style Formats) Chris Angelico <rosuav@gmail.com> - 2016-07-12 07:51 +1000
Re: What is precision of a number representation? (was: Curious Omission In New-Style Formats) Jan Coombs <jenfhaomndgfwutc@murmic.plus.com> - 2016-07-12 00:14 +0100
Re: What is precision of a number representation? (was: Curious Omission In New-Style Formats) Chris Angelico <rosuav@gmail.com> - 2016-07-12 09:57 +1000
Re: What is precision of a number representation? (was: Curious Omission In New-Style Formats) Steven D'Aprano <steve@pearwood.info> - 2016-07-12 14:19 +1000
Re: What is precision of a number representation? (was: Curious Omission In New-Style Formats) Chris Angelico <rosuav@gmail.com> - 2016-07-12 14:36 +1000
Re: What is precision of a number representation? Antoon Pardon <antoon.pardon@rece.vub.ac.be> - 2016-07-12 11:50 +0200
Re: What is precision of a number representation? Marko Rauhamaa <marko@pacujo.net> - 2016-07-12 13:27 +0300
Re: What is precision of a number representation? Antoon Pardon <antoon.pardon@rece.vub.ac.be> - 2016-07-12 13:02 +0200
Re: What is precision of a number representation? Steven D'Aprano <steve@pearwood.info> - 2016-07-12 23:16 +1000
Re: What is precision of a number representation? Ethan Furman <ethan@stoneleaf.us> - 2016-07-11 15:17 -0700
Re: What is precision of a number representation? Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2016-07-12 16:21 +1000
Re: What is precision of a number representation? Random832 <random832@fastmail.com> - 2016-07-12 09:36 -0400
Re: What is precision of a number representation? Ethan Furman <ethan@stoneleaf.us> - 2016-07-11 15:29 -0700
Re: Curious Omission In New-Style Formats Gregory Ewing <greg.ewing@canterbury.ac.nz> - 2016-07-12 11:26 +1200
Re: What is precision of a number representation? Chris Angelico <rosuav@gmail.com> - 2016-07-12 11:57 +1000
Re: What is precision of a number representation? Ben Finney <ben+python@benfinney.id.au> - 2016-07-12 13:41 +1000
Re: What is precision of a number representation? Terry Reedy <tjreedy@udel.edu> - 2016-07-12 00:14 -0400
Re: What is precision of a number representation? Terry Reedy <tjreedy@udel.edu> - 2016-07-12 00:17 -0400
csiph-web