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Re: IEEE floating point comparisons

Date 2026-05-05 11:32 +1000
Subject Re: IEEE floating point comparisons
Newsgroups comp.lang.forth
References <10t9259$3c72d$1@dont-email.me> <20260504094359.00003976@tin.it> <10ta3eo$3l84s$1@dont-email.me> <n5sboiFm58sU1@mid.individual.net>
From dxf <dxforth@gmail.com>
Message-ID <69f948bb$1@news.ausics.net> (permalink)
Organization Ausics - https://newsgroups.ausics.net

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On 5/05/2026 5:53 am, minforth wrote:
> Am 04.05.2026 um 14:29 schrieb Krishna Myneni:
>> ...
>> I included ieee-754.4th for Forth systems which did not have +/-INF and +/-NAN defined. It also provides the extremely useful words FINFINITE? and FNAN? to check for infinities and NANs resulting from calculations, as well as FSUBNORMAL? when the results are represented with less precision than standard double precision. These words are all part of David Williams' IEEE proposal.
>>
>> The rationale for the signed NAN is unclear to me, but I think David had a good reason to include it in his IEEE proposal. It may be useful in some numerical computation cases. I will look into this further.
>>
> The sign is merely an artefact of the preceding calculation and has no
> inherent significance. Even in applications that use NaN-boxing, the
> possible range of values does not include the bit position of the sign.

When creating constants that represent NAN the sign bit will necessarily
be there.  That's enough to include it in the identifier IMO.  Similarly
when displaying fp datum that happen to be NAN.  I would rather see more
information than less.  When I'm told something occurred "last year" it
only begs the question "exactly when?".


 

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Thread

IEEE floating point comparisons Krishna Myneni <krishna.myneni@ccreweb.org> - 2026-05-03 22:00 -0500
  Re: IEEE floating point comparisons Krishna Myneni <krishna.myneni@ccreweb.org> - 2026-05-03 22:18 -0500
  Re: IEEE floating point comparisons peter <peter.noreply@tin.it> - 2026-05-04 09:43 +0200
    Re: IEEE floating point comparisons Krishna Myneni <krishna.myneni@ccreweb.org> - 2026-05-04 07:29 -0500
      Re: IEEE floating point comparisons minforth <minforth@gmx.net> - 2026-05-04 21:53 +0200
        Re: IEEE floating point comparisons Krishna Myneni <krishna.myneni@ccreweb.org> - 2026-05-04 17:20 -0500
        Re: IEEE floating point comparisons dxf <dxforth@gmail.com> - 2026-05-05 11:32 +1000
  Re: IEEE floating point comparisons Krishna Myneni <krishna.myneni@ccreweb.org> - 2026-05-06 08:23 -0500

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