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

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Date	Wed, 1 Jun 2011 13:05:43 +1000
Subject	Re: float("nan") in set or as key
From	Chris Angelico <rosuav@gmail.com>
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On Wed, Jun 1, 2011 at 12:59 PM, Carl Banks <pavlovevidence@gmail.com> wrote:
> On Sunday, May 29, 2011 7:53:59 PM UTC-7, Chris Angelico wrote:
>> Okay, here's a question. The Python 'float' value - is it meant to be
>> "a Python representation of an IEEE double-precision floating point
>> value", or "a Python representation of a real number"?
>
> The former.  Unlike the case with integers, there is no way that I know of to represent an abstract real number on a digital computer.

This seems peculiar. Normally Python seeks to define its data types in
the abstract and then leave the concrete up to the various
implementations - note, for instance, how Python 3 has dispensed with
'int' vs 'long' and just made a single 'int' type that can hold any
integer. Does this mean that an implementation of Python on hardware
that has some other type of floating point must simulate IEEE
double-precision in all its nuances?

I'm glad I don't often need floating point numbers. They can be so annoying!

Chris Angelico

Thread

Re: float("nan") in set or as key Carl Banks <pavlovevidence@gmail.com> - 2011-05-31 19:59 -0700
  Re: float("nan") in set or as key Chris Angelico <rosuav@gmail.com> - 2011-06-01 13:05 +1000
    Re: float("nan") in set or as key Grant Edwards <invalid@invalid.invalid> - 2011-06-01 14:03 +0000
      Re: float("nan") in set or as key Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2011-06-02 01:10 +0000

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