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

Groups > comp.lang.python > #20999

Re: Python math is off by .000000000000045

Date 2012-02-28 09:56 -0800
From Ethan Furman <ethan@stoneleaf.us>
Subject Re: Python math is off by .000000000000045
References (4 earlier) <aa5ca147-b5ed-4f8c-935d-48b2c2cfac87@gr6g2000vbb.googlegroups.com> <4f4965f5$0$29989$c3e8da3$5496439d@news.astraweb.com> <cbd3219a-d379-4499-94ea-c4d0178a498f@db5g2000vbb.googlegroups.com> <4F4BBD4C.1050603@stoneleaf.us> <4F4C2595.6030207@gmail.com>
Newsgroups comp.lang.python
Message-ID <mailman.255.1330455205.3037.python-list@python.org> (permalink)

Show all headers | View raw

Michael Torrie wrote:
> He's simply showing you the hex (binary) representation of the
> floating-point number's binary representation.  As you can clearly see
> in the case of 1.1, there is no finite sequence that can store that.
> You end up with repeating numbers.  

Thanks for the explanation.

> This should help you understand why you get errors
> doing simple things like x/y*y doesn't quite get you back to x.

I already understood that.  I just didn't understand what point he was 
trying to make since he gave no explanation.

~Ethan~

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