Re: What is precision of a number representation?

From	Antoon Pardon <antoon.pardon@rece.vub.ac.be>
Newsgroups	comp.lang.python
Subject	Re: What is precision of a number representation?
Date	2016-07-12 13:02 +0200
Message-ID	<mailman.14.1468321397.21009.python-list@python.org> (permalink)
References	(11 earlier) <57846fdb$0$1593$c3e8da3$5496439d@news.astraweb.com> <5784BD63.20702@rece.vub.ac.be> <mailman.11.1468317141.21009.python-list@python.org> <87furfducw.fsf@elektro.pacujo.net> <5784CE4E.7040903@rece.vub.ac.be>

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Op 12-07-16 om 12:27 schreef Marko Rauhamaa:
> Antoon Pardon <antoon.pardon@rece.vub.ac.be>:
>
>> Op 12-07-16 om 06:19 schreef Steven D'Aprano:
>>> How do you represent 1 mm to a precision of four significant digits,
>>> in such a way that it is distinguished from 1 mm to one significant
>>> digit, and 1 mm to a precision of four decimal places?
>> A precision is an indication of a fault tolerance. You don't indicate
>> less fault tolerace by writing it as 0001.
>
>> Please explain how 0001 represants a difference in precision than just
>> 1.
> "Precision" here is not ordinary usage. Historically, it comes from the
> printf(3) library function:

Steven was talking about significant digits. So my use of precision
was in that context. So I think your printf here is irrelevant.

Talking about how your number is printed is different from talking
about the significance of the digits. If you for whatever reason want
to write 1 as 0001, be my guest.

If you state that this somehow expresses a difference in significant
digits, I would like someone to explain how. And yes I want that expressed
in difference of fault or error tolerance, because that is what IMO
significant digits refer to.

>
>> Now between which two numbers is 0001 supposed to be?
> What is your problem? What practical trouble is Python's format method
> giving you?

This is not about Python's format. This is about someone stating a
difference in significant digits.

-- 
Antoon.

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

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