Re: official library of tiny functions lacking in c

From	Lawrence D’Oliveiro <ldo@nz.invalid>
Newsgroups	comp.lang.c
Subject	Re: official library of tiny functions lacking in c
Date	2026-09-30 07:13 +0000
Organization	A noiseless patient Spider
Message-ID	<119icqv$5tm$1@dont-email.me> (permalink)
References	(8 earlier) <119dqk0$2cj9m$1@dont-email.me> <119fo4i$315co$2@dont-email.me> <119gge4$3bd3r$1@dont-email.me> <119hfr3$3nmbu$4@dont-email.me> <119hgmj$3o8kb$1@dont-email.me>

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On Wed, 30 Sep 2026 00:13:23 +0100, bart wrote:

> On 29/09/2026 23:58, Lawrence D’Oliveiro wrote:
>>
>> On Tue, 29 Sep 2026 15:02:43 +0100, bart wrote:
>>
>>> On 29/09/2026 08:08, Lawrence D’Oliveiro wrote:
>>>>
>>>> So the library routine is still capable of producing meaningful
>>>> results, while the naïve implementation still breaks down.
>>>>
>>>> Any more nitpicks?
>>>
>>> Yes: you're being incredibly pedantic and picky for no reason
>>> other than to be argumentative and superior.
>>
>> You’re the one failing to appreciate the point, that it takes
>> smarts to design proper numeric algorithms that work within the
>> practical *efficient* limits of computer arithmetic.
>
> OK, so give me a 'smart' square(x) routine where x can go all the
> way to the MAX value.

Maybe you need to read that paragraph again.

>>> These big numbers are ridiculous. If you want to play this game,
>>> then I've just got my bignum library ...
>>
>> So those numbers are “ridiculous”, yet your only way to counter
>> them is to be more “ridiculous”?
>
> Yes; they're all ridiculous. You're criticising some line-length
> routine because it goes wrong when deltas reach 10**19 (f32), or
> some 10**153 (f64) or 10**4000 or whatever (f80).

This is why we have floating-point numbers: so that we can have a
large dynamic range to cope with things like real physical data.
What’s the point of having that range if you can’t use most or all of
it? If, in fact, you can only use a small fraction, but you can’t
actually be sure what fraction that might be, because it’s not obvious
from the function?

> Mine I think will go wrong at 10**5000000000000000000 or something.
>
> But IT DOESN'T MATTER.

Yes it does. You forget that, before the widespread adoption of
IEEE-754, floating-point was a subject ridden with black-magic voodoo
spells that programmers had to adopt to try to minimize the chance of
surprising results on particular machine architectures.

It took decades for all those quirks to go extinct. Nobody wants them
back. It seems to be like vaccines: people have forgotten that, if you
take away the only thing keeping the disease out, you will go back to
the Bad Old Days of widespread pain and suffering.

> You're also looking at this wrong way: the author of len2() (ie. the
> 'naive' version) wrote it with his applications in mind, where its
> spec was perfectly adequate for the job.

I doubt that particular author had any kind of actual “application” in
mind. If they did, they would have found it simpler to just use the
existing function, instead of writing their own.

> As the author of a library function, you don't know to what applications
> it will be used for, so you don't make assumptions.

Precisely the point. That includes making assumptions that the user
will know that, even though the argument and expected result are both
within the representable range, some wayward intermediate result will
cause the whole calculation to blow up and produce a meaningless
result. When such a misfeature was totally avoidable.

> Also you're not going to get paid much for one line of code so you
> might as well go to town.

Or, you know, you could avoid wasting everybody’s time, shut up, and
use the existing wonderful library of readily available,
well-documented, standards-compliant open-source routines that already
do the job so well.

Thread

official library of tiny functions lacking in c fir <profesor.fir@gmail.com> - 2026-09-27 10:20 +0200
  Re: official library of tiny functions lacking in c fir <profesor.fir@gmail.com> - 2026-09-27 20:04 +0200
    Re: official library of tiny functions lacking in c bart <bc@freeuk.com> - 2026-09-27 21:38 +0100
      Re: official library of tiny functions lacking in c fir <profesor.fir@gmail.com> - 2026-09-27 23:16 +0200
        Re: official library of tiny functions lacking in c bart <bc@freeuk.com> - 2026-09-28 00:53 +0100
          Re: official library of tiny functions lacking in c fir <profesor.fir@gmail.com> - 2026-09-28 04:31 +0200
          Re: official library of tiny functions lacking in c David Brown <david.brown@hesbynett.no> - 2026-09-28 10:25 +0200
            Re: official library of tiny functions lacking in c bart <bc@freeuk.com> - 2026-09-28 11:45 +0100
              Re: official library of tiny functions lacking in c David Brown <david.brown@hesbynett.no> - 2026-09-28 13:56 +0200
                Re: official library of tiny functions lacking in c bart <bc@freeuk.com> - 2026-09-28 14:38 +0100
                Re: official library of tiny functions lacking in c David Brown <david.brown@hesbynett.no> - 2026-09-28 16:12 +0200
                Re: official library of tiny functions lacking in c bart <bc@freeuk.com> - 2026-09-28 16:52 +0100
                Re: official library of tiny functions lacking in c David Brown <david.brown@hesbynett.no> - 2026-09-28 18:49 +0200
                Re: official library of tiny functions lacking in c bart <bc@freeuk.com> - 2026-09-28 20:26 +0100
                Re: official library of tiny functions lacking in c David Brown <david.brown@hesbynett.no> - 2026-09-29 09:45 +0200
                Re: official library of tiny functions lacking in c bart <bc@freeuk.com> - 2026-09-29 12:54 +0100
                Re: official library of tiny functions lacking in c David Brown <david.brown@hesbynett.no> - 2026-09-29 15:56 +0200
                Re: official library of tiny functions lacking in c bart <bc@freeuk.com> - 2026-09-29 18:15 +0100
                Re: official library of tiny functions lacking in c David Brown <david.brown@hesbynett.no> - 2026-09-29 20:24 +0200
                Re: official library of tiny functions lacking in c scott@slp53.sl.home (Scott Lurndal) - 2026-09-29 19:41 +0000
                Re: official library of tiny functions lacking in c cross@spitfire.i.gajendra.net (Dan Cross) - 2026-09-29 21:37 +0000
                Re: official library of tiny functions lacking in c bart <bc@freeuk.com> - 2026-09-30 01:33 +0100
                Re: official library of tiny functions lacking in c David Brown <david.brown@hesbynett.no> - 2026-09-30 09:28 +0200
                Re: official library of tiny functions lacking in c Michael S <already5chosen@yahoo.com> - 2026-09-30 13:41 +0300
                Re: official library of tiny functions lacking in c Tim Rentsch <tr.17687@z991.linuxsc.com> - 2026-10-01 07:25 -0700
                Re: official library of tiny functions lacking in c Michael S <already5chosen@yahoo.com> - 2026-10-01 17:50 +0300
                Re: official library of tiny functions lacking in c Tim Rentsch <tr.17687@z991.linuxsc.com> - 2026-10-01 09:37 -0700
                Re: official library of tiny functions lacking in c bart <bc@freeuk.com> - 2026-09-30 01:19 +0100
                Re: official library of tiny functions lacking in c David Brown <david.brown@hesbynett.no> - 2026-09-30 09:44 +0200
                Re: official library of tiny functions lacking in c Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2026-09-29 16:01 +0200
                Re: official library of tiny functions lacking in c "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2026-09-30 01:00 -0700
                Re: official library of tiny functions lacking in c Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2026-09-30 13:01 +0200
                Re: official library of tiny functions lacking in c Lawrence D’Oliveiro <ldo@nz.invalid> - 2026-10-01 08:52 +0000
                Re: official library of tiny functions lacking in c Lawrence D’Oliveiro <ldo@nz.invalid> - 2026-09-30 01:56 +0000
                Re: official library of tiny functions lacking in c Tim Rentsch <tr.17687@z991.linuxsc.com> - 2026-10-01 07:15 -0700
                Re: official library of tiny functions lacking in c Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2026-09-29 09:28 +0200
                Re: official library of tiny functions lacking in c Lawrence D’Oliveiro <ldo@nz.invalid> - 2026-09-29 07:10 +0000
                Re: official library of tiny functions lacking in c "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2026-09-28 15:30 -0700
                Re: official library of tiny functions lacking in c Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2026-09-29 09:03 +0200
                Re: official library of tiny functions lacking in c bart <bc@freeuk.com> - 2026-09-29 11:11 +0100
                Re: official library of tiny functions lacking in c scott@slp53.sl.home (Scott Lurndal) - 2026-09-29 14:38 +0000
                Re: official library of tiny functions lacking in c Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2026-09-30 07:02 +0200
                Re: official library of tiny functions lacking in c bart <bc@freeuk.com> - 2026-09-30 11:35 +0100
                Re: official library of tiny functions lacking in c Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2026-09-30 14:14 +0200
                Re: official library of tiny functions lacking in c bart <bc@freeuk.com> - 2026-09-30 13:45 +0100
                Re: official library of tiny functions lacking in c David Brown <david.brown@hesbynett.no> - 2026-09-30 15:30 +0200
                Re: official library of tiny functions lacking in c Michael S <already5chosen@yahoo.com> - 2026-09-30 17:14 +0300
                Re: official library of tiny functions lacking in c David Brown <david.brown@hesbynett.no> - 2026-09-30 16:42 +0200
                Re: official library of tiny functions lacking in c Michael S <already5chosen@yahoo.com> - 2026-09-30 18:02 +0300
                Re: official library of tiny functions lacking in c bart <bc@freeuk.com> - 2026-09-30 16:54 +0100
                Re: official library of tiny functions lacking in c David Brown <david.brown@hesbynett.no> - 2026-09-30 18:26 +0200
                Re: official library of tiny functions lacking in c bart <bc@freeuk.com> - 2026-09-30 22:12 +0100
                Re: official library of tiny functions lacking in c David Brown <david.brown@hesbynett.no> - 2026-10-01 09:44 +0200
                Re: official library of tiny functions lacking in c bart <bc@freeuk.com> - 2026-10-01 10:42 +0100
                Re: official library of tiny functions lacking in c Michael S <already5chosen@yahoo.com> - 2026-10-01 13:50 +0300
                Re: official library of tiny functions lacking in c bart <bc@freeuk.com> - 2026-10-01 12:29 +0100
                Re: official library of tiny functions lacking in c David Brown <david.brown@hesbynett.no> - 2026-10-02 09:35 +0200
                Re: official library of tiny functions lacking in c Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2026-10-02 04:03 -0700
                Re: official library of tiny functions lacking in c David Brown <david.brown@hesbynett.no> - 2026-10-02 13:50 +0200
                Re: official library of tiny functions lacking in c Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2026-10-02 11:22 -0700
                Re: official library of tiny functions lacking in c gazelle@shell.xmission.com (Kenny McCormack) - 2026-10-02 18:33 +0000
                Re: official library of tiny functions lacking in c scott@slp53.sl.home (Scott Lurndal) - 2026-10-03 14:30 +0000
                Re: official library of tiny functions lacking in c Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2026-10-03 16:37 -0700
                Re: official library of tiny functions lacking in c David Brown <david.brown@hesbynett.no> - 2026-10-01 13:29 +0200
                Re: official library of tiny functions lacking in c scott@slp53.sl.home (Scott Lurndal) - 2026-10-01 14:46 +0000
                Re: official library of tiny functions lacking in c "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2026-10-01 15:37 -0700
                Re: official library of tiny functions lacking in c David Brown <david.brown@hesbynett.no> - 2026-10-02 08:57 +0200
                Re: official library of tiny functions lacking in c "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2026-10-02 00:37 -0700
                Re: official library of tiny functions lacking in c bart <bc@freeuk.com> - 2026-09-30 17:12 +0100
                Re: official library of tiny functions lacking in c Michael S <already5chosen@yahoo.com> - 2026-09-30 14:09 +0300
                Re: official library of tiny functions lacking in c David Brown <david.brown@hesbynett.no> - 2026-09-30 13:55 +0200
                Re: official library of tiny functions lacking in c Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2026-09-30 14:31 +0200
                Re: official library of tiny functions lacking in c Michael S <already5chosen@yahoo.com> - 2026-09-30 16:12 +0300
                Re: official library of tiny functions lacking in c Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2026-09-30 19:33 +0200
                Re: official library of tiny functions lacking in c scott@slp53.sl.home (Scott Lurndal) - 2026-09-30 18:14 +0000
                Re: official library of tiny functions lacking in c James Kuyper <jameskuyper@alumni.caltech.edu> - 2026-10-01 08:34 -0400
                Re: official library of tiny functions lacking in c Lawrence D’Oliveiro <ldo@nz.invalid> - 2026-09-29 07:08 +0000
                Re: official library of tiny functions lacking in c bart <bc@freeuk.com> - 2026-09-29 15:02 +0100
                Re: official library of tiny functions lacking in c scott@slp53.sl.home (Scott Lurndal) - 2026-09-29 14:43 +0000
                Re: official library of tiny functions lacking in c bart <bc@freeuk.com> - 2026-09-29 16:07 +0100
                Re: official library of tiny functions lacking in c Lawrence D’Oliveiro <ldo@nz.invalid> - 2026-09-29 22:58 +0000
                Re: official library of tiny functions lacking in c bart <bc@freeuk.com> - 2026-09-30 00:13 +0100
                Re: official library of tiny functions lacking in c Lawrence D’Oliveiro <ldo@nz.invalid> - 2026-09-30 07:13 +0000
                Re: official library of tiny functions lacking in c Johann 'Myrkraverk' Oskarsson <johann@myrkraverk.invalid> - 2026-10-01 02:41 +0800
                Re: official library of tiny functions lacking in c Michael S <already5chosen@yahoo.com> - 2026-09-30 14:15 +0300
                Re: official library of tiny functions lacking in c Michael S <already5chosen@yahoo.com> - 2026-09-30 14:18 +0300
                Re: official library of tiny functions lacking in c bart <bc@freeuk.com> - 2026-09-30 13:24 +0100
                Re: official library of tiny functions lacking in c Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2026-09-30 14:45 +0200
                Re: official library of tiny functions lacking in c Michael S <already5chosen@yahoo.com> - 2026-09-30 15:56 +0300
                Re: official library of tiny functions lacking in c Lawrence D’Oliveiro <ldo@nz.invalid> - 2026-09-30 22:31 +0000
                Re: official library of tiny functions lacking in c Michael S <already5chosen@yahoo.com> - 2026-09-30 14:32 +0300
                Re: official library of tiny functions lacking in c fir <profesor.fir@gmail.com> - 2026-09-28 17:22 +0200
                Re: official library of tiny functions lacking in c Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2026-09-28 17:24 -0700
                Re: official library of tiny functions lacking in c David Brown <david.brown@hesbynett.no> - 2026-09-29 09:54 +0200
                Re: official library of tiny functions lacking in c "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2026-09-29 16:48 -0700
              Re: official library of tiny functions lacking in c Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2026-09-28 14:16 +0200
              Re: official library of tiny functions lacking in c James Kuyper <jameskuyper@alumni.caltech.edu> - 2026-09-28 11:15 -0400
                Re: official library of tiny functions lacking in c bart <bc@freeuk.com> - 2026-09-28 16:40 +0100
                Re: official library of tiny functions lacking in c "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2026-09-29 16:50 -0700
              Re: official library of tiny functions lacking in c Lawrence D’Oliveiro <ldo@nz.invalid> - 2026-09-29 06:38 +0000
                Re: official library of tiny functions lacking in c bart <bc@freeuk.com> - 2026-09-29 14:36 +0100
                Re: official library of tiny functions lacking in c Lawrence D’Oliveiro <ldo@nz.invalid> - 2026-09-29 22:49 +0000
                Re: official library of tiny functions lacking in c bart <bc@freeuk.com> - 2026-09-29 23:59 +0100
                Re: official library of tiny functions lacking in c "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2026-09-29 16:51 -0700
                Re: official library of tiny functions lacking in c Lawrence D’Oliveiro <ldo@nz.invalid> - 2026-09-30 01:54 +0000
                Re: official library of tiny functions lacking in c James Kuyper <jameskuyper@alumni.caltech.edu> - 2026-09-29 22:09 -0400
                Re: official library of tiny functions lacking in c bart <bc@freeuk.com> - 2026-09-30 10:52 +0100
                Re: official library of tiny functions lacking in c David Brown <david.brown@hesbynett.no> - 2026-09-30 12:38 +0200
                Re: official library of tiny functions lacking in c Lawrence D’Oliveiro <ldo@nz.invalid> - 2026-10-01 08:49 +0000
                Re: official library of tiny functions lacking in c James Kuyper <jameskuyper@alumni.caltech.edu> - 2026-10-01 08:48 -0400
    Re: official library of tiny functions lacking in c Lawrence D’Oliveiro <ldo@nz.invalid> - 2026-09-28 06:45 +0000
      Re: official library of tiny functions lacking in c fir <profesor.fir@gmail.com> - 2026-09-28 12:42 +0200
        Re: official library of tiny functions lacking in c Lawrence D’Oliveiro <ldo@nz.invalid> - 2026-09-29 00:58 +0000
          Re: official library of tiny functions lacking in c fir <profesor.fir@gmail.com> - 2026-09-29 03:02 +0200
            Re: official library of tiny functions lacking in c Lawrence D’Oliveiro <ldo@nz.invalid> - 2026-09-29 03:16 +0000
              Re: official library of tiny functions lacking in c fir <profesor.fir@gmail.com> - 2026-09-29 14:20 +0200
                Re: official library of tiny functions lacking in c Paul <nospam@needed.invalid> - 2026-09-29 12:39 -0400
                Re: official library of tiny functions lacking in c Lawrence D’Oliveiro <ldo@nz.invalid> - 2026-09-29 22:50 +0000
                Re: official library of tiny functions lacking in c fir <profesor.fir@gmail.com> - 2026-09-30 02:57 +0200
                Re: official library of tiny functions lacking in c Lawrence D’Oliveiro <ldo@nz.invalid> - 2026-09-30 02:00 +0000
                Re: official library of tiny functions lacking in c fir <profesor.fir@gmail.com> - 2026-09-30 10:08 +0200
                Re: official library of tiny functions lacking in c fir <profesor.fir@gmail.com> - 2026-09-30 13:58 +0200
      Re: official library of tiny functions lacking in c bart <bc@freeuk.com> - 2026-09-28 11:43 +0100
        Re: official library of tiny functions lacking in c Lawrence D’Oliveiro <ldo@nz.invalid> - 2026-09-29 01:00 +0000
        Re: official library of tiny functions lacking in c Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2026-09-30 07:59 +0200
      Re: official library of tiny functions lacking in c James Kuyper <jameskuyper@alumni.caltech.edu> - 2026-09-28 11:03 -0400
    Re: official library of tiny functions lacking in c NOTE fir <profesor.fir@gmail.com> - 2026-09-28 17:50 +0200
    Re: official library of tiny functions lacking in c "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2026-09-30 12:42 -0700
  Re: official library of tiny functions lacking in c tTh <tth@none.invalid> - 2026-09-28 00:02 +0200

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