Re: official library of tiny functions lacking in c

From	bart <bc@freeuk.com>
Newsgroups	comp.lang.c
Subject	Re: official library of tiny functions lacking in c
Date	2026-09-30 13:24 +0100
Organization	A noiseless patient Spider
Message-ID	<119iv2e$7clk$1@dont-email.me> (permalink)
References	(10 earlier) <119gge4$3bd3r$1@dont-email.me> <119hfr3$3nmbu$4@dont-email.me> <119hgmj$3o8kb$1@dont-email.me> <20260930141545.00006dda@yahoo.com> <20260930141835.000007ce@yahoo.com>

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On 30/09/2026 12:18, Michael S wrote:
> On Wed, 30 Sep 2026 14:15:45 +0300
> Michael S <already5chosen@yahoo.com> wrote:
> 
>> On Wed, 30 Sep 2026 00:13:23 +0100
>> bart <bc@freeuk.com> 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.
>>>    
>>
>> Come on. You are certainly good enough programmer to figure it out
>> yourself. It should not take more than few minutes.
>>
>> If you want hint, it is in the followup.
>>
> 
> frexp
> 

I don't see how that helps. My made-up square function has a signature 
like (T)->T, and T will have a particular T.MAX value.

So, what is the maximum input that can yield a result that can still be 
represented within a type T? Presumably it is +/- sqrt(T.MAX).

The broader point is that pretty much any arithmetic involving floats 
can overflow the range if the magnitudes are large enough (or small 
enough with divide etc).

You can still work with this, since the ranges of f32 and especially f64 
are generous enough. (And if using the x87 FPU, intermediates use f80.)

In the very, very specific case of hypot, then being able to work with 
as large a range as possible via clever tricks is great, but there is no 
great practical need.

Certainly not enough to dismiss the 'naive' solution out of hand, 
especially if it is faster.

I stated elsewhere that I often worked with 'x*x + y*y' without 
bothering with the square root, so here that cleverness won't help.

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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