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

Groups > comp.lang.python > #20865

Re: Python math is off by .000000000000045

Return-Path <python-python-list@m.gmane.org>
X-Original-To python-list@python.org
Delivered-To python-list@mail.python.org
X-Spam-Status OK 0.001
X-Spam-Evidence '*H*': 1.00; '*S*': 0.00; 'subject:Python': 0.05; 'received:verizon.net': 0.07; 'terry': 0.07; 'received:80.91': 0.09; 'received:80.91.229': 0.09; 'received:gmane.org': 0.09; 'received:list': 0.09; 'substitute': 0.09; 'binary': 0.13; 'ranges.': 0.16; 'reedy': 0.16; 'wrote:': 0.18; 'example.': 0.18; 'jan': 0.19; 'seems': 0.20; 'header:In-Reply-To:1': 0.22; 'similarly': 0.23; 'subject: .': 0.29; 'pm,': 0.29; 'there': 0.33; 'header:User-Agent:1': 0.33; 'header:X-Complaints-To:1': 0.34; 'certain': 0.34; 'fraction': 0.34; 'integer': 0.34; 'numbers.': 0.34; 'to:addr:python-list': 0.35; 'received:org': 0.36; 'represent': 0.37; 'point': 0.40; 'to:addr:python.org': 0.40; 'more': 0.61; '12:56': 0.84
X-Injected-Via-Gmane http://gmane.org/
To python-list@python.org
From Terry Reedy <tjreedy@udel.edu>
Subject Re: Python math is off by .000000000000045
Date Sat, 25 Feb 2012 16:05:05 -0500
References <mailman.49.1329934400.3037.python-list@python.org> <ji3kb2$hk3$1@reader1.panix.com> <wh92r.13653$1I2.11412@newsfe08.iad>
Mime-Version 1.0
Content-Type text/plain; charset=UTF-8; format=flowed
Content-Transfer-Encoding 7bit
X-Gmane-NNTP-Posting-Host pool-74-109-121-73.phlapa.fios.verizon.net
User-Agent Mozilla/5.0 (Windows NT 6.1; WOW64; rv:8.0) Gecko/20111105 Thunderbird/8.0
In-Reply-To <wh92r.13653$1I2.11412@newsfe08.iad>
X-BeenThere python-list@python.org
X-Mailman-Version 2.1.12
Precedence list
List-Id General discussion list for the Python programming language <python-list.python.org>
List-Unsubscribe <http://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 <http://mail.python.org/mailman/listinfo/python-list>, <mailto:python-list-request@python.org?subject=subscribe>
Newsgroups comp.lang.python
Message-ID <mailman.162.1330203944.3037.python-list@python.org> (permalink)
Lines 14
NNTP-Posting-Host 2001:888:2000:d::a6
X-Trace 1330203944 news.xs4all.nl 6962 [2001:888:2000:d::a6]:47430
X-Complaints-To abuse@xs4all.nl
Path csiph.com!x330-a1.tempe.blueboxinc.net!usenet.pasdenom.info!bete-des-vosges.org!feed.ac-versailles.fr!usenet-fr.net!de-l.enfer-du-nord.net!feeder2.enfer-du-nord.net!cs.uu.nl!news.stack.nl!newsfeed.xs4all.nl!newsfeed5.news.xs4all.nl!xs4all!post.news.xs4all.nl!not-for-mail
Xref x330-a1.tempe.blueboxinc.net comp.lang.python:20865

Show key headers only | View raw

On 2/25/2012 12:56 PM, Tobiah wrote:

> It seems to me that there are a great many real numbers that can be
> represented exactly by floating point numbers. The number 1 is an
> example.

Binary floats can represent and integer and any fraction with a 
denominator of 2**n within certain ranges. For decimal floats, 
substitute 10**n or more exactly, 2**j * 5**k since if J < k,
n / (2**j * 5**k) = (n * 2**(k-j)) / 10**k and similarly if j > k.

-- 
Terry Jan Reedy

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

Thread

Python math is off by .000000000000045 Alec Taylor <alec.taylor6@gmail.com> - 2012-02-23 05:13 +1100
  Re: Python math is off by .000000000000045 nn <pruebauno@latinmail.com> - 2012-02-22 10:29 -0800
  Re: Python math is off by .000000000000045 Jussi Piitulainen <jpiitula@ling.helsinki.fi> - 2012-02-22 20:44 +0200
  Re: Python math is off by .000000000000045 Grant Edwards <invalid@invalid.invalid> - 2012-02-22 20:48 +0000
    Re: Python math is off by .000000000000045 Tobiah <toby@tobiah.org> - 2012-02-25 09:56 -0800
      Re: Python math is off by .000000000000045 Tim Wintle <tim.wintle@teamrubber.com> - 2012-02-25 19:08 +0000
      Re: Python math is off by .000000000000045 Terry Reedy <tjreedy@udel.edu> - 2012-02-25 16:05 -0500
        Re: Python math is off by .000000000000045 jmfauth <wxjmfauth@gmail.com> - 2012-02-25 13:25 -0800
          Re: Python math is off by .000000000000045 Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2012-02-25 22:51 +0000
            Re: Python math is off by .000000000000045 jmfauth <wxjmfauth@gmail.com> - 2012-02-26 01:59 -0800
              Re: Python math is off by .000000000000045 Ethan Furman <ethan@stoneleaf.us> - 2012-02-27 09:28 -0800
              Re: Python math is off by .000000000000045 Michael Torrie <torriem@gmail.com> - 2012-02-27 17:53 -0700
              Re: Python math is off by .000000000000045 Ethan Furman <ethan@stoneleaf.us> - 2012-02-28 09:56 -0800
      Re: Python math is off by .000000000000045 Devin Jeanpierre <jeanpierreda@gmail.com> - 2012-02-25 21:49 -0500
      Re: Python math is off by .000000000000045 Terry Reedy <tjreedy@udel.edu> - 2012-02-26 00:44 -0500
  Re: Python math is off by .000000000000045 John Ladasky <ladasky@my-deja.com> - 2012-02-26 16:24 -0800
    Re: Python math is off by .000000000000045 Terry Reedy <tjreedy@udel.edu> - 2012-02-26 20:30 -0500
    Re: Python math is off by .000000000000045 Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2012-02-27 03:28 +0000
      Re: Python math is off by .000000000000045 Grant Edwards <invalid@invalid.invalid> - 2012-02-27 15:02 +0000
        Re: Python math is off by .000000000000045 Michael Torrie <torriem@gmail.com> - 2012-02-27 08:34 -0700

csiph-web