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

Groups > comp.lang.python > #83421

Re: Decimals and other numbers

From Marko Rauhamaa <marko@pacujo.net>
Newsgroups comp.lang.python
Subject Re: Decimals and other numbers
Date 2015-01-09 11:44 +0200
Organization A noiseless patient Spider
Message-ID <87fvbke19r.fsf@elektro.pacujo.net> (permalink)
References <CABicbJK-5izGtet8BsS1Yqx+6AHMX7gLU4zYjjt5jULJXNVipA@mail.gmail.com> <54AF405C.6020609@davea.name> <mailman.17501.1420772593.18130.python-list@python.org> <54af9612$0$12995$c3e8da3$5496439d@news.astraweb.com>

Show all headers | View raw

Steven D'Aprano <steve+comp.lang.python@pearwood.info>:

> Devin Jeanpierre wrote:
> No you can't -- that would make arithmetic inconsistent. 0**1 is
> perfectly well defined as 0 however you look at it:

You *could* leave 0**1 undefined. You *could* leave 7+0 undefined.
However, that would make mathematical proofs more complex as they would
be riddled with if/else branches.

That's the whole point of silly "no-op" definitions such as a+0 or b**1;
they make mathematical proofs much more concise and feasible. It is
precious to be able to have such "ideal" cases defined, and you'd like
to do it everywhere. Unfortunately, it is not possible everywhere so you
just have to supply the necessary if/else branches in your proof.


Marko

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

Thread

Re: Decimals and other numbers Devin Jeanpierre <jeanpierreda@gmail.com> - 2015-01-08 19:02 -0800
  Re: Decimals and other numbers Marko Rauhamaa <marko@pacujo.net> - 2015-01-09 09:28 +0200
    Re: Decimals and other numbers Chris Angelico <rosuav@gmail.com> - 2015-01-09 18:37 +1100
      Re: Decimals and other numbers Marko Rauhamaa <marko@pacujo.net> - 2015-01-09 11:31 +0200
    Re: Decimals and other numbers Dave Angel <davea@davea.name> - 2015-01-09 02:49 -0500
    Re: Decimals and other numbers Devin Jeanpierre <jeanpierreda@gmail.com> - 2015-01-09 00:51 -0800
      Re: Decimals and other numbers Jussi Piitulainen <jpiitula@ling.helsinki.fi> - 2015-01-09 11:07 +0200
        [OT] x**y == y**x Peter Pearson <pkpearson@nowhere.invalid> - 2015-01-09 17:46 +0000
          Re: [OT] x**y == y**x Marko Rauhamaa <marko@pacujo.net> - 2015-01-09 23:41 +0200
            Re: [OT] x**y == y**x Peter Pearson <pkpearson@nowhere.invalid> - 2015-01-10 16:57 +0000
  Re: Decimals and other numbers Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2015-01-09 19:49 +1100
    Re: Decimals and other numbers Devin Jeanpierre <jeanpierreda@gmail.com> - 2015-01-09 00:58 -0800
      Re: Decimals and other numbers Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2015-01-09 21:20 +1100
        Re: Decimals and other numbers Chris Angelico <rosuav@gmail.com> - 2015-01-09 21:39 +1100
          Re: Decimals and other numbers Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2015-01-09 23:24 +1100
            Re: Decimals and other numbers Chris Angelico <rosuav@gmail.com> - 2015-01-09 23:34 +1100
        Re: Decimals and other numbers Devin Jeanpierre <jeanpierreda@gmail.com> - 2015-01-09 17:25 -0800
        Re: Decimals and other numbers Gregory Ewing <greg.ewing@canterbury.ac.nz> - 2015-01-10 16:08 +1300
    Re: Decimals and other numbers Devin Jeanpierre <jeanpierreda@gmail.com> - 2015-01-09 01:11 -0800
    Re: Decimals and other numbers Marko Rauhamaa <marko@pacujo.net> - 2015-01-09 11:34 +0200
      Re: Decimals and other numbers Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2015-01-09 22:03 +1100
    Re: Decimals and other numbers Marko Rauhamaa <marko@pacujo.net> - 2015-01-09 11:44 +0200
    Re: Decimals and other numbers Gregory Ewing <greg.ewing@canterbury.ac.nz> - 2015-01-10 16:05 +1300
      Re: Decimals and other numbers Devin Jeanpierre <jeanpierreda@gmail.com> - 2015-01-09 19:57 -0800

csiph-web