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Re: How the computer identify an NaN?

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Heinrich Wolf <invalid@invalid.invalid> wrote:

> "bert" <bert.hutchings@btinternet.com> schrieb im Newsbeitrag 
> news:0e6e63f1-e63e-4e52-9db5-ec1807044878@glegroupsg2000goo.googlegroups.com...
> ...
> >> ex:
> >> b_u = 3;
> >> (b_u!=b_u) ==> 1, right?
> >>
> >> Have you tried?
> >> I doubt that.
> >>
> > You should listen more carefully when
> > people who have a complete understanding
> > of some topic try to explain it to you.
> >
> > Where 'b' is a real, (b != b) is 1 or 0,
> > depending strictly on whether the current
> > value of 'b' is a NaN, or is not a NaN.
> > --

> pardon?
> I noticed that b_u is a real which results in 3.0 by assignment;
> Why should (3.0 != 3.0) result in 1? 

You snipped the most relevant part of your own post, i.e.

>>> If NaN won't equal to anything, any number will not equal to itself
>>> either. I still do not understand b_u != b_u;

and the statement made by "bert" was that

   b != b

evaluates to 1 if b is not-NaN (e.g. for b set to 3) but to 0
if b is NaN (always assuming that IEEE floating point represen-
tation is used).

The claim you made (and then snipped in your reply) is wrong
(that's not a question of logic but due to the way things are
required by the IEEE standard for floating point handling) and
that's what the "Have you tried" was refering to.

                             Regards, Jens
-- 
  \   Jens Thoms Toerring  ___      jt@toerring.de
   \__________________________      http://toerring.de

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Thread

How the computer identify an NaN? fl <rxjwg98@gmail.com> - 2011-08-15 20:19 -0700
  Re: How the computer identify an NaN? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2011-08-16 04:33 +0100
    Re: How the computer identify an NaN? fl <rxjwg98@gmail.com> - 2011-08-15 21:45 -0700
      Re: How the computer identify an NaN? Robert Wessel <robertwessel2@yahoo.com> - 2011-08-16 00:45 -0500
      Re: How the computer identify an NaN? "Heinrich Wolf" <invalid@invalid.invalid> - 2011-08-16 08:51 +0200
        Re: How the computer identify an NaN? bert <bert.hutchings@btinternet.com> - 2011-08-16 02:01 -0700
          Re: How the computer identify an NaN? "Heinrich Wolf" <invalid@invalid.invalid> - 2011-08-16 13:04 +0200
            Re: How the computer identify an NaN? jt@toerring.de (Jens Thoms Toerring) - 2011-08-16 11:28 +0000
              Re: How the computer identify an NaN? jt@toerring.de (Jens Thoms Toerring) - 2011-08-16 11:31 +0000
                Re: How the computer identify an NaN? "Heinrich Wolf" <invalid@invalid.invalid> - 2011-08-16 14:08 +0200
              Re: How the computer identify an NaN? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2011-08-16 13:37 +0100
                Re: How the computer identify an NaN? jt@toerring.de (Jens Thoms Toerring) - 2011-08-16 21:13 +0000
            Re: How the computer identify an NaN? "Heinrich Wolf" <invalid@invalid.invalid> - 2011-08-16 14:17 +0200
          Re: How the computer identify an NaN? "Heinrich Wolf" <invalid@invalid.invalid> - 2011-08-16 13:22 +0200
            Re: How the computer identify an NaN? Angel <angel+news@spamcop.net> - 2011-08-16 15:17 +0000
      Re: How the computer identify an NaN? James Kuyper <jameskuyper@verizon.net> - 2011-08-16 08:42 -0400
      Re: How the computer identify an NaN? Stephen Sprunk <stephen@sprunk.org> - 2011-08-16 09:25 -0500
      Re: How the computer identify an NaN? Joe Pfeiffer <pfeiffer@cs.nmsu.edu> - 2011-08-16 12:37 -0600
        Re: How the computer identify an NaN? Keith Thompson <kst-u@mib.org> - 2011-08-16 12:26 -0700

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