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

Groups > comp.lang.python > #7068

Re: float("nan") in set or as key

Show all headers | View raw

On Mon, Jun 6, 2011 at 11:21 AM, Steven D'Aprano
<steve+comp.lang.python@pearwood.info> wrote:
> The intended behaviour is operations on "quiet NANs" should return NANs,
> but operations on "signalling NANs" should cause a trap, which can either
> be ignored, and converted into a quiet NAN, or treated as an exception.
>
> E.g. in Decimal: [snip]

So does this mean that:

a = 0.0/0.0
b = a + 1

(with signalling NANs) should trap on the second line but not the
first? That's the first "operation on a nan".

> http://www.cs.berkeley.edu/~wkahan/JAVAhurt.pdf
> (The article is seven years old now, but as far as I know, the criticisms
> still apply.)

Thanks, that's my travel-home literature for tonight! :) I read the
other two articles you sent me (asynchronously), and they're most
interesting. I'm definitely still inclined to avoid any sort of
floating point work if at all possible, but hey, this gives me more
topics to bore people with at parties! (Wait. I never get invited to
parties any more. I think my work on that front is complete.)

Chris Angelico

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

Thread

Re: float("nan") in set or as key Carl Banks <pavlovevidence@gmail.com> - 2011-06-03 13:27 -0700
  Re: float("nan") in set or as key Chris Angelico <rosuav@gmail.com> - 2011-06-04 06:35 +1000
    Re: float("nan") in set or as key Chris Torek <nospam@torek.net> - 2011-06-05 22:54 +0000
      Re: float("nan") in set or as key Chris Angelico <rosuav@gmail.com> - 2011-06-06 09:13 +1000
        Re: float("nan") in set or as key Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2011-06-06 01:21 +0000
          Re: float("nan") in set or as key Chris Torek <nospam@torek.net> - 2011-06-06 01:56 +0000
          Re: float("nan") in set or as key Chris Angelico <rosuav@gmail.com> - 2011-06-06 14:11 +1000
            Re: float("nan") in set or as key Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2011-06-06 04:59 +0000
              Re: float("nan") in set or as key Chris Angelico <rosuav@gmail.com> - 2011-06-06 15:10 +1000
  Re: float("nan") in set or as key Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2011-06-04 04:54 +0000
    Re: float("nan") in set or as key Ethan Furman <ethan@stoneleaf.us> - 2011-06-03 23:04 -0700
      Re: float("nan") in set or as key Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2011-06-04 09:35 +0000
        Re: float("nan") in set or as key Ben Finney <ben+python@benfinney.id.au> - 2011-06-04 20:20 +1000
        Re: float("nan") in set or as key Ethan Furman <ethan@stoneleaf.us> - 2011-06-04 14:28 -0700
        Re: float("nan") in set or as key Robert Kern <robert.kern@gmail.com> - 2011-06-04 16:49 -0500
          Re: float("nan") in set or as key Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2011-06-05 02:03 +0000
            Re: float("nan") in set or as key Robert Kern <robert.kern@gmail.com> - 2011-06-05 14:44 -0500

csiph-web