Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > comp.lang.python > #110080

Re: value of pi and 22/7

Path csiph.com!fu-berlin.de!uni-berlin.de!not-for-mail
From Ethan Furman <ethan@stoneleaf.us>
Newsgroups comp.lang.python
Subject Re: value of pi and 22/7
Date Fri, 17 Jun 2016 19:27:08 -0700
Lines 35
Message-ID <mailman.110.1466216834.2288.python-list@python.org> (permalink)
References <AANLkTimAOpGtTvq2GMWG+hbT3SapkT9k8RuDriQHnQc9@mail.gmail.com> <mailman.1021.1300384117.1189.python-list@python.org> <d1e74d2a-e426-4017-9cb7-0512c64a2e3d@r3g2000yqh.googlegroups.com> <ilvpg9$2k8$1@reader1.panix.com> <91940d31-1ff4-4267-9b07-445eca35d234@googlegroups.com> <CALwzidnqyDKZ=9MBpu9QiF4Lk+MduEmvQ3L9CSknb60kP=zSCA@mail.gmail.com> <mailman.107.1466207356.2288.python-list@python.org> <5764a19c$0$1603$c3e8da3$5496439d@news.astraweb.com> <5764B17C.3080809@stoneleaf.us>
Mime-Version 1.0
Content-Type text/plain; charset=windows-1252; format=flowed
Content-Transfer-Encoding 7bit
X-Trace news.uni-berlin.de +nkNhsSkPnA4F/NkcCEpkwB0VDIp0r7ms+hB8G8Tif0A==
Return-Path <ethan@stoneleaf.us>
X-Original-To python-list@python.org
Delivered-To python-list@mail.python.org
X-Spam-Status OK 0.048
X-Spam-Evidence '*H*': 0.91; '*S*': 0.00; 'from:addr:ethan': 0.09; 'from:addr:stoneleaf.us': 0.09; 'from:name:ethan furman': 0.09; 'message-id:@stoneleaf.us': 0.09; 'do,': 0.15; '2016': 0.16; 'digits.': 0.16; 'measurement': 0.16; 'notations': 0.16; 'received:io': 0.16; 'received:psf.io': 0.16; 'wrote:': 0.16; 'am,': 0.23; 'sat,': 0.23; 'header:In-Reply-To:1': 0.24; 'header :User-Agent:1': 0.26; 'figure': 0.27; 'followed': 0.27; 'not.': 0.27; '~ethan~': 0.29; 'subject:/': 0.30; 'maybe': 0.33; "d'aprano": 0.33; 'steven': 0.33; 'mine': 0.35; 'but': 0.36; 'to:addr:python-list': 0.36; 'pm,': 0.36; 'subject:: ': 0.37; 'two': 0.37; 'to:addr:python.org': 0.40; 'some': 0.40; 'your': 0.60; 'charset:windows-1252': 0.62; 'date,': 0.66; 'eight': 0.72; 'physical': 0.72; 'again!': 0.84; 'digits?': 0.84; 'phenomenon': 0.84; 'subject:value': 0.84; 'widespread': 0.91
User-Agent Mozilla/5.0 (X11; Linux i686; rv:31.0) Gecko/20100101 Thunderbird/31.2.0
In-Reply-To <5764a19c$0$1603$c3e8da3$5496439d@news.astraweb.com>
X-BeenThere python-list@python.org
X-Mailman-Version 2.1.22
Precedence list
List-Id General discussion list for the Python programming language <python-list.python.org>
List-Unsubscribe <https://mail.python.org/mailman/options/python-list>, <mailto:python-list-request@python.org?subject=unsubscribe>
List-Archive <http://mail.python.org/pipermail/python-list/>
List-Post <mailto:python-list@python.org>
List-Help <mailto:python-list-request@python.org?subject=help>
List-Subscribe <https://mail.python.org/mailman/listinfo/python-list>, <mailto:python-list-request@python.org?subject=subscribe>
X-Mailman-Original-Message-ID <5764B17C.3080809@stoneleaf.us>
X-Mailman-Original-References <AANLkTimAOpGtTvq2GMWG+hbT3SapkT9k8RuDriQHnQc9@mail.gmail.com> <mailman.1021.1300384117.1189.python-list@python.org> <d1e74d2a-e426-4017-9cb7-0512c64a2e3d@r3g2000yqh.googlegroups.com> <ilvpg9$2k8$1@reader1.panix.com> <91940d31-1ff4-4267-9b07-445eca35d234@googlegroups.com> <CALwzidnqyDKZ=9MBpu9QiF4Lk+MduEmvQ3L9CSknb60kP=zSCA@mail.gmail.com> <mailman.107.1466207356.2288.python-list@python.org> <5764a19c$0$1603$c3e8da3$5496439d@news.astraweb.com>
Xref csiph.com comp.lang.python:110080

Show key headers only | View raw

On 06/17/2016 06:19 PM, Steven D'Aprano wrote:
> On Sat, 18 Jun 2016 09:49 am, Ian Kelly wrote:

>> If I tell you that the speed of light is 300,000,000 m/s, do you think
>> that measurement has 9 significant digits? If you do, then you would be
>> wrong.
>
> Hmmm.
>
> If I tell you that some physical phenomenon [let's call it the speed of
> light] is 299,999,999 m/s, how many significant digits would I be using?

I know!  I know!  9!

> What if I tell you that it's 300,000,001 m/s?

Oh!  9 again!

> What if the figure to nine significant digits *actually is* three followed
> by eight zeroes?

Hmmm... thinking.... thinking... oh yeah!  You put a bar over the last 
significant digit -- or you use scientific notation:

30e7 has two significant digits.

> For all that it is in widespread use, I think the concept of "significant
> figures" is inherently ambiguous.

Not at all -- just have to keep your notations correct*.

--
~Ethan~

* Mine might be 30 years out of date, but maybe not.

Back to comp.lang.python | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread

Thread

Re: value of pi and 22/7 Lawrence D’Oliveiro <lawrencedo99@gmail.com> - 2016-06-17 16:12 -0700
  Re: value of pi and 22/7 Ian Kelly <ian.g.kelly@gmail.com> - 2016-06-17 17:49 -0600
    Re: value of pi and 22/7 Steven D'Aprano <steve@pearwood.info> - 2016-06-18 11:19 +1000
      Re: value of pi and 22/7 Ethan Furman <ethan@stoneleaf.us> - 2016-06-17 19:27 -0700
      Re: value of pi and 22/7 Tim Harig <timharig@eternal-september.org> - 2016-06-18 05:47 +0000
        Re: value of pi and 22/7 boB Stepp <robertvstepp@gmail.com> - 2016-06-18 10:22 -0500
      Re: value of pi and 22/7 Christian Gollwitzer <auriocus@gmx.de> - 2016-06-18 09:56 +0200
  Re: value of pi and 22/7 Random832 <random832@fastmail.com> - 2016-06-17 23:48 -0400
    Re: value of pi and 22/7 Lawrence D’Oliveiro <lawrencedo99@gmail.com> - 2016-06-17 21:30 -0700
      Re: value of pi and 22/7 Ian Kelly <ian.g.kelly@gmail.com> - 2016-06-17 23:18 -0600
        Re: value of pi and 22/7 Gregory Ewing <greg.ewing@canterbury.ac.nz> - 2016-06-20 10:25 +1200
          Re: value of pi and 22/7 Steven D'Aprano <steve@pearwood.info> - 2016-06-20 12:07 +1000
            Re: value of pi and 22/7 Grant Edwards <grant.b.edwards@gmail.com> - 2016-06-20 18:06 +0000
          Re: value of pi and 22/7 Ian Kelly <ian.g.kelly@gmail.com> - 2016-06-19 23:19 -0600
            Re: value of pi and 22/7 Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2016-06-20 16:22 +1000
              Re: value of pi and 22/7 Ian Kelly <ian.g.kelly@gmail.com> - 2016-06-20 10:01 -0600
                Re: value of pi and 22/7 Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2016-06-21 18:38 +1000
              Re: value of pi and 22/7 Ian Kelly <ian.g.kelly@gmail.com> - 2016-06-20 10:09 -0600
          Re: value of pi and 22/7 Lawrence D’Oliveiro <lawrencedo99@gmail.com> - 2016-06-19 22:51 -0700
            Re: value of pi and 22/7 Marko Rauhamaa <marko@pacujo.net> - 2016-06-20 10:32 +0300
              Re: value of pi and 22/7 Lawrence D’Oliveiro <lawrencedo99@gmail.com> - 2016-06-20 01:01 -0700
                Re: value of pi and 22/7 Wildman <best_lay@yahoo.com> - 2016-06-20 17:24 -0500
                Re: value of pi and 22/7 Marko Rauhamaa <marko@pacujo.net> - 2016-06-21 01:47 +0300
                Re: value of pi and 22/7 Lawrence D’Oliveiro <lawrencedo99@gmail.com> - 2016-06-22 14:20 -0700
      Re: value of pi and 22/7 Gregory Ewing <greg.ewing@canterbury.ac.nz> - 2016-06-20 10:14 +1200
        Re: value of pi and 22/7 Grant Edwards <grant.b.edwards@gmail.com> - 2016-06-20 17:53 +0000
        Re: value of pi and 22/7 Marko Rauhamaa <marko@pacujo.net> - 2016-06-20 21:52 +0300
          Re: value of pi and 22/7 Gregory Ewing <greg.ewing@canterbury.ac.nz> - 2016-06-22 00:52 +1200
  Re: value of pi and 22/7 Pete Forman <petef4+usenet@gmail.com> - 2016-06-18 13:05 +0100
  Re: value of pi and 22/7 Johannes Bauer <dfnsonfsduifb@gmx.de> - 2016-06-18 18:09 +0200

csiph-web