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Re: Default signedness of 'plain' char.

From BGB <cr88192@gmail.com>
Newsgroups comp.lang.c
Subject Re: Default signedness of 'plain' char.
Date 2026-08-13 23:50 -0500
Organization A noiseless patient Spider
Message-ID <115m73a$285f3$2@dont-email.me> (permalink)
References (14 earlier) <115djoi$3h06u$1@dont-email.me> <115dot7$3ihmr$1@dont-email.me> <115dv3d$3k3jl$1@dont-email.me> <115feen$3msd$1@dont-email.me> <115g1p6$aeop$2@dont-email.me>

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On 8/11/2026 3:47 PM, Chris M. Thomasson wrote:
> On 8/11/2026 8:17 AM, James Kuyper wrote:
>> On 2026-08-10 21:44, BGB wrote:
>>> On 8/10/2026 7:03 PM, James Kuyper wrote:
>>>> On 2026-08-10 18:31, BGB wrote:
>>>> ...> Snipped section included my epic fail at trying to use traditional
>>>> style
>>>>> mathematical notation in a Usenet post...
>>>>>
>>>>> It was bugging me, by implying the conjugate was a scalar, where 
>>>>> no, the
>>>>> conjugate is not a scalar...
>>>>
>>>> I'm not sure what you're saying. As far as C is concerned. complex 
>>>> types
>>>> are floating types (6.2.5p15), and therefore arithmetic types
>>>> (6.2.5p23), and therefore scalar types (6.2.5p26) Therefore, a function
>>>> that returns the conjugate of its argument would return a scalar type.
>>>
>>> I wrote:
>>>     R^-1 = (R.r-R.i-R.j-R.k) / (R.r*R.r + R.i*R.i + R.j*R.j + R.k*R.k)
>>>
>>> The problem:
>>>     (R.r-R.i-R.j-R.k)
>>> Should have been, say:
>>>     (R.r - R.i*I - R.j*J - R.k*K)
>>>
>>> Which was bugging me, because either the former would be interpreted as
>>> meaning a scalar (or real-valued) result, or "R.i*R.i" as being
>>> negative, neither of which was true in the intended expression...
>>
>> I was confused because you were writing about complex numbers, mentioned
>> that you had snipped some material, and then made a comment that I
>> assumed, from context, was also about complex numbers. I did not realize
>> that there was a context switch to quaternions inside the snipped 
>> material.
>> In the unlikely event that that were added to C, quaternions would
>> almost certainly be added as a new arithmetic (and therefore, scalar)
>> type, by analogy with the complex types. I was unaware, until just now
>> when I looked it up, that the real part of a quaternion is often
>> referred to as it's scalar part.
>> That's a little odd, because I'm one of the probably very few people
>> here who've actually made practical use of quaternions. I had to deal
>> with data about spacecraft orientation that was stored as a quaternion,
>> and convert between quaternions and corresponding Euler angles and
>> Rotation matrices. However, a quaternion library was part of the
>> standard toolkit for that project, which makes sense.
> 
> quaternion are very useful for such things. Avoiding gimbal lock?

Among other things:
No gimbal lock;
Can LERP/SLERP;
SLERP'ing between identity and a given rotation allows scaling the rotation;
Can be used as a vector for angular velocity or angular inertia math;
Can be multiplied for compound rotations (like with matrix math);

Try to SLERP a matrix, and it may "rubber band" or have other weird 
glitches;
Try to LERP Euler angles and the motion may end up going in some totally 
weird direction;
...

If you use two of them (a "dual quaternion"), it is possible to express 
fairly arbitrary transforms (translation + rotation).

Like, were pretty useful for doing something like a rigid-body physics 
engine, even if the physics engine itself turned out to not be very useful.

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Default signedness of 'plain' char. gazelle@shell.xmission.com (Kenny McCormack) - 2026-08-02 14:17 +0000
  Re: Default signedness of 'plain' char. Johann 'Myrkraverk' Oskarsson <johann@myrkraverk.invalid> - 2026-08-03 02:45 +0800
    Re: Default signedness of 'plain' char. gazelle@shell.xmission.com (Kenny McCormack) - 2026-08-03 01:47 +0000
      Re: Default signedness of 'plain' char. Johann 'Myrkraverk' Oskarsson <johann@myrkraverk.invalid> - 2026-08-03 23:14 +0800
        Re: Default signedness of 'plain' char. bart <bc@freeuk.com> - 2026-08-03 17:04 +0100
          The Spanish Inquisition (was: Re: Default signedness of 'plain' char.) Johann 'Myrkraverk' Oskarsson <johann@myrkraverk.invalid> - 2026-08-04 00:23 +0800
            Re: The Spanish Inquisition bart <bc@freeuk.com> - 2026-08-03 18:03 +0100
              Re: The Spanish Inquisition Johann 'Myrkraverk' Oskarsson <johann@myrkraverk.invalid> - 2026-08-04 01:26 +0800
        Re: Default signedness of 'plain' char. Theo <theom+news@chiark.greenend.org.uk> - 2026-08-04 13:13 +0100
          Re: Default signedness of 'plain' char. Lawrence D’Oliveiro <ldo@nz.invalid> - 2026-08-05 07:30 +0000
            Re: Default signedness of 'plain' char. Johann 'Myrkraverk' Oskarsson <johann@myrkraverk.invalid> - 2026-08-05 18:18 +0800
              Re: Default signedness of 'plain' char. bart <bc@freeuk.com> - 2026-08-05 17:20 +0100
                Re: Default signedness of 'plain' char. Lawrence D’Oliveiro <ldo@nz.invalid> - 2026-08-05 21:57 +0000
                Re: Default signedness of 'plain' char. Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2026-08-05 15:29 -0700
  Re: Default signedness of 'plain' char. David Brown <david.brown@hesbynett.no> - 2026-08-03 09:56 +0200
    Re: Default signedness of 'plain' char. BGB <cr88192@gmail.com> - 2026-08-03 13:56 -0500
  Re: Default signedness of 'plain' char. antispam@fricas.org (Waldek Hebisch) - 2026-08-03 13:48 +0000
  Re: Default signedness of 'plain' char. cross@spitfire.i.gajendra.net (Dan Cross) - 2026-08-03 14:47 +0000
  Re: Default signedness of 'plain' char. Lew Pitcher <lew.pitcher@digitalfreehold.ca> - 2026-08-03 14:47 +0000
    Re: Default signedness of 'plain' char. Lew Pitcher <lew.pitcher@digitalfreehold.ca> - 2026-08-03 15:04 +0000
      Re: Default signedness of 'plain' char. Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2026-08-03 16:58 -0700
        Re: Default signedness of 'plain' char. Lew Pitcher <lew.pitcher@digitalfreehold.ca> - 2026-08-04 15:10 +0000
          Re: Default signedness of 'plain' char. scott@slp53.sl.home (Scott Lurndal) - 2026-08-04 15:50 +0000
          Re: Default signedness of 'plain' char. Lawrence D’Oliveiro <ldo@nz.invalid> - 2026-08-05 03:00 +0000
          Re: Default signedness of 'plain' char. David Brown <david.brown@hesbynett.no> - 2026-08-05 09:01 +0200
      Re: Default signedness of 'plain' char. antispam@fricas.org (Waldek Hebisch) - 2026-08-04 18:10 +0000
        Compilers targetting the C64 (was: Re: Default signedness of 'plain' char.) Johann 'Myrkraverk' Oskarsson <johann@myrkraverk.invalid> - 2026-08-05 03:17 +0800
        Re: Default signedness of 'plain' char. BGB <cr88192@gmail.com> - 2026-08-04 16:25 -0500
        Re: Default signedness of 'plain' char. Lawrence D’Oliveiro <ldo@nz.invalid> - 2026-08-05 02:57 +0000
          Re: Default signedness of 'plain' char. Lynn McGuire <lynnmcguire5@gmail.com> - 2026-08-05 00:19 -0500
            Re: Default signedness of 'plain' char. Johann 'Myrkraverk' Oskarsson <johann@myrkraverk.invalid> - 2026-08-05 18:57 +0800
            Re: Default signedness of 'plain' char. scott@slp53.sl.home (Scott Lurndal) - 2026-08-05 14:33 +0000
            Re: Default signedness of 'plain' char. cross@spitfire.i.gajendra.net (Dan Cross) - 2026-08-05 22:38 +0000
        Re: Default signedness of 'plain' char. Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2026-08-04 21:36 -0700
          Re: Default signedness of 'plain' char. antispam@fricas.org (Waldek Hebisch) - 2026-08-06 00:21 +0000
  Re: Default signedness of 'plain' char. "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2026-08-03 13:20 -0700
    Re: Default signedness of 'plain' char. bart <bc@freeuk.com> - 2026-08-03 22:06 +0100
      Re: Default signedness of 'plain' char. "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2026-08-03 14:25 -0700
        Re: Default signedness of 'plain' char. BGB <cr88192@gmail.com> - 2026-08-03 18:38 -0500
          Re: Default signedness of 'plain' char. "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2026-08-03 19:34 -0700
            Re: Default signedness of 'plain' char. BGB <cr88192@gmail.com> - 2026-08-05 04:40 -0500
          Re: Default signedness of 'plain' char. Lawrence D’Oliveiro <ldo@nz.invalid> - 2026-08-05 07:22 +0000
            Re: Default signedness of 'plain' char. BGB <cr88192@gmail.com> - 2026-08-05 04:02 -0500
              Re: Default signedness of 'plain' char. David Brown <david.brown@hesbynett.no> - 2026-08-05 12:35 +0200
              Re: Default signedness of 'plain' char. Johann 'Myrkraverk' Oskarsson <johann@myrkraverk.invalid> - 2026-08-05 18:49 +0800
                Re: Default signedness of 'plain' char. "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2026-08-05 12:39 -0700
                Dear Chris (was: Re: Default signedness of 'plain' char.) Johann 'Myrkraverk' Oskarsson <johann@myrkraverk.invalid> - 2026-08-06 20:15 +0800
                Re: Dear Chris bart <bc@freeuk.com> - 2026-08-06 15:05 +0100
                Re: Dear Chris Johann 'Myrkraverk' Oskarsson <johann@myrkraverk.invalid> - 2026-08-06 23:16 +0800
                Re: Dear Chris David Brown <david.brown@hesbynett.no> - 2026-08-06 20:10 +0200
              Re: Default signedness of 'plain' char. Lawrence D’Oliveiro <ldo@nz.invalid> - 2026-08-05 21:54 +0000
                Re: Default signedness of 'plain' char. BGB <cr88192@gmail.com> - 2026-08-06 04:49 -0500
                Re: Default signedness of 'plain' char. Lawrence D’Oliveiro <ldo@nz.invalid> - 2026-08-07 00:10 +0000
                Re: Default signedness of 'plain' char. David Brown <david.brown@hesbynett.no> - 2026-08-07 09:56 +0200
            Re: Default signedness of 'plain' char. James Kuyper <jameskuyper@alumni.caltech.edu> - 2026-08-05 13:33 -0400
              Re: Default signedness of 'plain' char. Lawrence D’Oliveiro <ldo@nz.invalid> - 2026-08-05 21:50 +0000
                Re: Default signedness of 'plain' char. David Brown <david.brown@hesbynett.no> - 2026-08-06 10:34 +0200
                Re: Default signedness of 'plain' char. BGB <cr88192@gmail.com> - 2026-08-09 15:19 -0500
                Re: Default signedness of 'plain' char. Lawrence D’Oliveiro <ldo@nz.invalid> - 2026-08-09 20:33 +0000
                Re: Default signedness of 'plain' char. "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2026-08-09 18:04 -0700
                Re: Default signedness of 'plain' char. Lawrence D’Oliveiro <ldo@nz.invalid> - 2026-08-10 02:45 +0000
                Re: Default signedness of 'plain' char. "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2026-08-10 02:24 -0700
                Re: Default signedness of 'plain' char. "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2026-08-09 18:03 -0700
                Re: Default signedness of 'plain' char. David Brown <david.brown@hesbynett.no> - 2026-08-10 08:58 +0200
                Re: Default signedness of 'plain' char. BGB <cr88192@gmail.com> - 2026-08-10 15:17 -0500
                Re: Default signedness of 'plain' char. Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2026-08-10 15:19 -0700
                Re: Default signedness of 'plain' char. BGB <cr88192@gmail.com> - 2026-08-10 17:31 -0500
                Re: Default signedness of 'plain' char. Lawrence D’Oliveiro <ldo@nz.invalid> - 2026-08-10 23:48 +0000
                Re: Default signedness of 'plain' char. James Kuyper <jameskuyper@alumni.caltech.edu> - 2026-08-10 20:03 -0400
                Re: Default signedness of 'plain' char. BGB <cr88192@gmail.com> - 2026-08-10 20:44 -0500
                Re: Default signedness of 'plain' char. James Kuyper <jameskuyper@alumni.caltech.edu> - 2026-08-11 11:17 -0400
                Re: Default signedness of 'plain' char. BGB <cr88192@gmail.com> - 2026-08-11 14:54 -0500
                Re: Quaternions (was Re: Default signedness of 'plain' char.) Lawrence D’Oliveiro <ldo@nz.invalid> - 2026-08-12 03:36 +0000
                Re: Quaternions (was Re: Default signedness of 'plain' char.) BGB <cr88192@gmail.com> - 2026-08-12 01:24 -0500
                Re: Quaternions (was Re: Default signedness of 'plain' char.) Lawrence D’Oliveiro <ldo@nz.invalid> - 2026-08-12 07:47 +0000
                Re: Quaternions (was Re: Default signedness of 'plain' char.) "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2026-08-12 12:52 -0700
                Re: Quaternions (was Re: Default signedness of 'plain' char.) "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2026-08-12 12:56 -0700
                Re: Quaternions (was Re: Default signedness of 'plain' char.) Lawrence D’Oliveiro <ldo@nz.invalid> - 2026-08-13 02:16 +0000
                Re: Quaternions (was Re: Default signedness of 'plain' char.) "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2026-08-12 21:04 -0700
                Re: Quaternions (was Re: Default signedness of 'plain' char.) BGB <cr88192@gmail.com> - 2026-08-12 23:07 -0500
                Re: Quaternions (was Re: Default signedness of 'plain' char.) Lawrence D’Oliveiro <ldo@nz.invalid> - 2026-08-13 05:00 +0000
                Re: Quaternions (was Re: Default signedness of 'plain' char.) BGB <cr88192@gmail.com> - 2026-08-13 04:37 -0500
                Re: Quaternions (was Re: Default signedness of 'plain' char.) "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2026-08-13 14:36 -0700
                Re: Quaternions (was Re: Default signedness of 'plain' char.) BGB <cr88192@gmail.com> - 2026-08-13 23:07 -0500
                Re: Quaternions (was Re: Default signedness of 'plain' char.) Lawrence D’Oliveiro <ldo@nz.invalid> - 2026-08-13 23:44 +0000
                Re: Quaternions (was Re: Default signedness of 'plain' char.) "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2026-08-13 18:50 -0700
                Re: Quaternions (was Re: Default signedness of 'plain' char.) Lawrence D’Oliveiro <ldo@nz.invalid> - 2026-08-14 02:41 +0000
                Re: Quaternions (was Re: Default signedness of 'plain' char.) BGB <cr88192@gmail.com> - 2026-08-13 23:47 -0500
                Re: Quaternions (was Re: Default signedness of 'plain' char.) Lawrence D’Oliveiro <ldo@nz.invalid> - 2026-08-14 04:59 +0000
                Re: Default signedness of 'plain' char. "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2026-08-11 13:47 -0700
                Re: Default signedness of 'plain' char. BGB <cr88192@gmail.com> - 2026-08-13 23:50 -0500
                Re: Default signedness of 'plain' char. Lawrence D’Oliveiro <ldo@nz.invalid> - 2026-08-14 05:59 +0000
                Re: Default signedness of 'plain' char. BGB <cr88192@gmail.com> - 2026-08-14 03:16 -0500
                Re: Default signedness of 'plain' char. Lawrence D’Oliveiro <ldo@nz.invalid> - 2026-08-14 08:32 +0000
                Re: Default signedness of 'plain' char. "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2026-08-14 12:36 -0700
                Re: Default signedness of 'plain' char. Lawrence D’Oliveiro <ldo@nz.invalid> - 2026-08-15 03:16 +0000
                Re: Default signedness of 'plain' char. "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2026-08-14 22:38 -0700
                Re: Default signedness of 'plain' char. Lawrence D’Oliveiro <ldo@nz.invalid> - 2026-08-16 00:08 +0000
                Re: Default signedness of 'plain' char. "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2026-08-14 12:17 -0700
                Re: Default signedness of 'plain' char. cross@spitfire.i.gajendra.net (Dan Cross) - 2026-08-11 13:46 +0000
                Re: Default signedness of 'plain' char. "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2026-08-11 13:49 -0700
                Re: Default signedness of 'plain' char. David Brown <david.brown@hesbynett.no> - 2026-08-11 08:58 +0200
                Re: Default signedness of 'plain' char. BGB <cr88192@gmail.com> - 2026-08-11 04:03 -0500
                Re: Default signedness of 'plain' char. steve g <Sgonedes1977@gmail.com> - 2026-08-10 20:29 -0400
                Re: Vectors! Quaternions! (was Re: Default signedness of 'plain' char.) Lawrence D’Oliveiro <ldo@nz.invalid> - 2026-08-11 03:58 +0000
                Re: Default signedness of 'plain' char. David Brown <david.brown@hesbynett.no> - 2026-08-11 09:06 +0200
                Re: Default signedness of 'plain' char. Ross Finlayson <ross.a.finlayson@gmail.com> - 2026-08-10 21:15 -0700
                Re: Default signedness of 'plain' char. Lawrence D’Oliveiro <ldo@nz.invalid> - 2026-08-11 04:52 +0000
                Re: Default signedness of 'plain' char. Ross Finlayson <ross.a.finlayson@gmail.com> - 2026-08-11 06:45 -0700
                Re: Default signedness of 'plain' char. "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2026-08-11 14:01 -0700
            Re: Default signedness of 'plain' char. "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2026-08-05 12:36 -0700
    Re: Default signedness of 'plain' char. Lawrence D’Oliveiro <ldo@nz.invalid> - 2026-08-05 07:18 +0000
  Re: Default signedness of 'plain' char. Lynn McGuire <lynnmcguire5@gmail.com> - 2026-08-05 18:30 -0500
    Re: Default signedness of 'plain' char. Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2026-08-05 16:41 -0700
      Re: Default signedness of 'plain' char. bart <bc@freeuk.com> - 2026-08-06 01:24 +0100
        Re: Default signedness of 'plain' char. Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2026-08-05 17:46 -0700
        Re: Default signedness of 'plain' char. cross@spitfire.i.gajendra.net (Dan Cross) - 2026-08-06 22:59 +0000
          Re: Default signedness of 'plain' char. Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2026-08-06 19:54 -0700
            Re: Default signedness of 'plain' char. cross@spitfire.i.gajendra.net (Dan Cross) - 2026-08-07 11:02 +0000
              Re: Default signedness of 'plain' char. Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2026-08-07 10:35 -0700
                Re: Default signedness of 'plain' char. cross@spitfire.i.gajendra.net (Dan Cross) - 2026-08-07 18:32 +0000
                Re: Default signedness of 'plain' char. Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2026-08-07 20:55 +0200
              Use of isascii() back in early days (was Re: Default signedness of 'plain' char.) Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2026-08-07 20:51 +0200
                Re: Use of isascii() back in early days (was Re: Default signedness of 'plain' char.) Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2026-08-07 13:03 -0700
                Re: Use of isascii() back in early days (was Re: Default signedness of 'plain' char.) Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2026-08-07 13:32 -0700
                Re: Use of isascii() back in early days (was Re: Default signedness of 'plain' char.) cross@spitfire.i.gajendra.net (Dan Cross) - 2026-08-07 21:44 +0000
                Re: Use of isascii() back in early days (was Re: Default signedness of 'plain' char.) Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2026-08-07 23:47 +0200
                Re: Use of isascii() back in early days (was Re: Default signedness of 'plain' char.) Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2026-08-07 15:26 -0700
      Re: Default signedness of 'plain' char. cross@spitfire.i.gajendra.net (Dan Cross) - 2026-08-06 22:57 +0000
        Re: Default signedness of 'plain' char. Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2026-08-06 18:23 -0700
          Re: Default signedness of 'plain' char. cross@spitfire.i.gajendra.net (Dan Cross) - 2026-08-07 11:47 +0000
    Re: Default signedness of 'plain' char. scott@slp53.sl.home (Scott Lurndal) - 2026-08-06 14:40 +0000
      Re: Default signedness of 'plain' char. Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2026-08-06 15:33 -0700

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