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Groups > comp.lang.c > #155140
| From | Keith Thompson <Keith.S.Thompson+u@gmail.com> |
|---|---|
| Newsgroups | comp.lang.c |
| Subject | Re: Microsoft Will now support C11 and C17 standard!!!!!!!!!! |
| Date | 2020-09-18 20:09 -0700 |
| Organization | None to speak of |
| Message-ID | <87imcacvj6.fsf@nosuchdomain.example.com> (permalink) |
| References | (5 earlier) <7d838b58-49a1-43ca-a579-a54ff0d7f0e7o@googlegroups.com> <rk3dpq$85a$1@dont-email.me> <rk3kqj$puv$1@dont-email.me> <rk3qus$4fp$1@dont-email.me> <rk3rl4$8j6$1@dont-email.me> |
James Kuyper <jameskuyper@alumni.caltech.edu> writes:
> On 9/18/20 10:38 PM, BGB wrote:
>> On 9/18/2020 7:53 PM, James Kuyper wrote:
>>> On 9/18/20 6:53 PM, BGB wrote:
>>> ...
>>>> In my compiler, both _Complex and _Imaginary are handled essentially as
>>>> 2-element vector types (which in turn allow cast-conversion with some
>>>> other types).
>>>
>>> Why in the world are you handling _Imaginary as a "2-element vector
>>> type"? The whole point of, for example, double _Imaginary is that the
>>> real part is guaranteed to be exactly 0.0, which allows it to store only
>>> the imaginary part, the same way that plain double has an imaginary part
>>> that is guaranteed to be exactly 0.0, which allows double to store only
>>> the real part.
>>> Situations where _Imaginary is useful are relatively rare, but it's also
>>> optional. I don't see the point in implementing it unless you implement
>>> it so that sizeof(double _Imaginary) == sizeof(double).
>>
>> Implementing _Imaginary as a 2-element vector means that both it and
>> _Complex can be treated as more-or-less equivalent as far as the backend
>> is concerned (with the primary difference between them being that the
>> real part of an _Imaginary always holds zero).
>
> Any application for which such an implementation would be acceptable
> would have been written to use _Complex, not _Imaginary. Properly
> implemented _Imaginary is not only half as big as _Complex, but can also
> substantially reduce the number of elementary floating point operations
> that need to be performed. Virtually by definition, any application that
> bothers to use _Imaginary would be using it precisely because those
> benefits are important to that application.
And N1570 Annex G says:
Each imaginary type has the same representation and alignment
requirements as the corresponding real type. The value of an object
of imaginary type is the value of the real representation times the
imaginary unit.
Support for imaginary types is optional.
I'm actually a bit unclear on the requirements for imaginary types
(_Imaginary float, _Imaginary double, _Imaginary long double). N1570
Annex G, which is normative, says:
This annex supplements annex F to specify complex arithmetic for
compatibility with IEC 60559 real floating-point arithmetic. An
implementation that defines __STDC_IEC_559_COMPLEX__ shall conform
to the specifications in this annex.
Both gcc and clang define __STDC_IEC_559_COMPLEX__, but neither
supports imaginary types. And a footnote in 6.4.1 (Keywords)
merely says that "One possible specification for imaginary types
appears in annex G.", which seems oddly vague. The latest C2X
draft I have, N2479, doesn't make any relevant changes. (In C99,
Annex G was informative, and it said "should conform" rather than
"shall conform".)
Are gcc and clang non-conforming, or am I missing something?
>> Then again, I guess it is possible that it could be made to have a
>> special purpose behavior that it is stored as a single element in memory
>> (while still being two element once loaded into a register).
>
> Not only it that possible, it's the whole point of having such a type,
> which was carefully designed to ensure that it was possible.
--
Keith Thompson (The_Other_Keith) Keith.S.Thompson+u@gmail.com
Working, but not speaking, for Philips Healthcare
void Void(void) { Void(); } /* The recursive call of the void */
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Microsoft Will now support C11 and C17 standard!!!!!!!!!! Real Troll <real.troll@trolls.com> - 2020-09-16 04:55 -1000
Re: Microsoft Will now support C11 and C17 standard!!!!!!!!!! Jens Stuckelberger <Jens_Stuckelberger@nowhere.net> - 2020-09-16 15:23 +0000
Re: Microsoft Will now support C11 and C17 standard!!!!!!!!!! Bonita Montero <Bonita.Montero@gmail.com> - 2020-09-16 17:49 +0200
Re: Microsoft Will now support C11 and C17 standard!!!!!!!!!! "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2020-09-16 12:53 -0700
Re: Microsoft Will now support C11 and C17 standard!!!!!!!!!! scott@slp53.sl.home (Scott Lurndal) - 2020-09-16 19:58 +0000
Re: Microsoft Will now support C11 and C17 standard!!!!!!!!!! doctor@doctor.nl2k.ab.ca (The Doctor) - 2020-09-16 22:31 +0000
Re: Microsoft Will now support C11 and C17 standard!!!!!!!!!! "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2020-09-16 21:10 -0700
Re: Microsoft Will now support C11 and C17 standard!!!!!!!!!! Bonita Montero <Bonita.Montero@gmail.com> - 2020-09-17 12:28 +0200
Re: Microsoft Will now support C11 and C17 standard!!!!!!!!!! "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2020-09-17 17:00 -0700
Re: Microsoft Will now support C11 and C17 standard!!!!!!!!!! Anton Shepelev <anton.txt@gmail.com> - 2020-09-17 02:13 +0300
Re: Microsoft Will now support C11 and C17 standard!!!!!!!!!! Bonita Montero <Bonita.Montero@gmail.com> - 2020-09-17 07:44 +0200
Re: Microsoft Will now support C11 and C17 standard!!!!!!!!!! Manfred <noname@add.invalid> - 2020-09-18 22:08 +0200
Re: Microsoft Will now support C11 and C17 standard!!!!!!!!!! Bonita Montero <Bonita.Montero@gmail.com> - 2020-09-19 06:54 +0200
Re: Microsoft Will now support C11 and C17 standard!!!!!!!!!! gazelle@shell.xmission.com (Kenny McCormack) - 2020-09-17 11:05 +0000
Re: Microsoft Will now support C11 and C17 standard!!!!!!!!!! Andrey Tarasevich <andreytarasevich@hotmail.com> - 2020-09-20 00:41 -0700
Re: Microsoft Will now support C11 and C17 standard!!!!!!!!!! Bonita Montero <Bonita.Montero@gmail.com> - 2020-09-20 11:03 +0200
Re: Microsoft Will now support C11 and C17 standard!!!!!!!!!! Manfred <noname@add.invalid> - 2020-09-20 15:51 +0200
Re: Microsoft Will now support C11 and C17 standard!!!!!!!!!! Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2020-09-20 07:41 -0700
Re: Microsoft Will now support C11 and C17 standard!!!!!!!!!! scott@slp53.sl.home (Scott Lurndal) - 2020-09-20 14:41 +0000
Re: Microsoft Will now support C11 and C17 standard!!!!!!!!!! scott@slp53.sl.home (Scott Lurndal) - 2020-09-20 14:39 +0000
Re: Microsoft Will now support C11 and C17 standard!!!!!!!!!! Bonita Montero <Bonita.Montero@gmail.com> - 2020-09-20 16:55 +0200
Re: Microsoft Will now support C11 and C17 standard!!!!!!!!!! David Brown <david.brown@hesbynett.no> - 2020-09-20 17:10 +0200
Re: Microsoft Will now support C11 and C17 standard!!!!!!!!!! Bonita Montero <Bonita.Montero@gmail.com> - 2020-09-20 18:14 +0200
Re: Microsoft Will now support C11 and C17 standard!!!!!!!!!! already5chosen@yahoo.com - 2020-09-20 10:44 -0700
Re: Microsoft Will now support C11 and C17 standard!!!!!!!!!! David Brown <david.brown@hesbynett.no> - 2020-09-20 21:14 +0200
Re: Microsoft Will now support C11 and C17 standard!!!!!!!!!! already5chosen@yahoo.com - 2020-09-20 15:40 -0700
Re: Microsoft Will now support C11 and C17 standard!!!!!!!!!! David Brown <david.brown@hesbynett.no> - 2020-09-21 08:34 +0200
Re: Microsoft Will now support C11 and C17 standard!!!!!!!!!! BGB <cr88192@gmail.com> - 2020-09-20 12:55 -0500
Re: Microsoft Will now support C11 and C17 standard!!!!!!!!!! David Brown <david.brown@hesbynett.no> - 2020-09-20 21:16 +0200
Re: Microsoft Will now support C11 and C17 standard!!!!!!!!!! Bart <bc@freeuk.com> - 2020-09-20 20:40 +0100
Re: Microsoft Will now support C11 and C17 standard!!!!!!!!!! BGB <cr88192@gmail.com> - 2020-09-20 19:39 -0500
Re: Microsoft Will now support C11 and C17 standard!!!!!!!!!! David Brown <david.brown@hesbynett.no> - 2020-09-21 09:20 +0200
Re: Microsoft Will now support C11 and C17 standard!!!!!!!!!! Bart <bc@freeuk.com> - 2020-09-21 11:25 +0100
Re: Microsoft Will now support C11 and C17 standard!!!!!!!!!! David Brown <david.brown@hesbynett.no> - 2020-09-21 14:27 +0200
Re: Microsoft Will now support C11 and C17 standard!!!!!!!!!! "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2020-09-21 22:24 -0700
Re: Microsoft Will now support C11 and C17 standard!!!!!!!!!! Bonita Montero <Bonita.Montero@gmail.com> - 2020-09-22 08:49 +0200
Re: Microsoft Will now support C11 and C17 standard!!!!!!!!!! Manfred <noname@add.invalid> - 2020-09-21 15:09 +0200
Re: Microsoft Will now support C11 and C17 standard!!!!!!!!!! Manfred <noname@add.invalid> - 2020-09-21 15:26 +0200
Re: Microsoft Will now support C11 and C17 standard!!!!!!!!!! Bart <bc@freeuk.com> - 2020-09-21 11:40 +0100
Re: Microsoft Will now support C11 and C17 standard!!!!!!!!!! David Brown <david.brown@hesbynett.no> - 2020-09-21 14:48 +0200
Re: Microsoft Will now support C11 and C17 standard!!!!!!!!!! Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2020-09-21 06:03 -0700
Re: Microsoft Will now support C11 and C17 standard!!!!!!!!!! Bart <bc@freeuk.com> - 2020-09-21 16:44 +0100
Re: Microsoft Will now support C11 and C17 standard!!!!!!!!!! BGB <cr88192@gmail.com> - 2020-09-21 12:06 -0500
Re: Microsoft Will now support C11 and C17 standard!!!!!!!!!! Bart <bc@freeuk.com> - 2020-09-21 20:03 +0100
Re: Microsoft Will now support C11 and C17 standard!!!!!!!!!! BGB <cr88192@gmail.com> - 2020-09-21 18:33 -0500
Re: Microsoft Will now support C11 and C17 standard!!!!!!!!!! BGB <cr88192@gmail.com> - 2020-09-21 11:09 -0500
Re: Microsoft Will now support C11 and C17 standard!!!!!!!!!! Jorgen Grahn <grahn+nntp@snipabacken.se> - 2020-09-20 16:13 +0000
Re: Microsoft Will now support C11 and C17 standard!!!!!!!!!! Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2020-09-20 09:53 -0700
Re: Microsoft Will now support C11 and C17 standard!!!!!!!!!! "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2020-09-16 12:51 -0700
Re: Microsoft Will now support C11 and C17 standard!!!!!!!!!! Ben Bacarisse <ben.usenet@bsb.me.uk> - 2020-09-16 21:00 +0100
Re: Microsoft Will now support C11 and C17 standard!!!!!!!!!! Thiago Adams <thiago.adams@gmail.com> - 2020-09-17 05:28 -0700
Re: Microsoft Will now support C11 and C17 standard!!!!!!!!!! "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2020-09-17 17:03 -0700
Re: Microsoft Will now support C11 and C17 standard!!!!!!!!!! Leo <usenet@gkbrk.com> - 2020-09-17 16:45 +0300
Re: Microsoft Will now support C11 and C17 standard!!!!!!!!!! Bonita Montero <Bonita.Montero@gmail.com> - 2020-09-17 16:59 +0200
Re: Microsoft Will now support C11 and C17 standard!!!!!!!!!! gazelle@shell.xmission.com (Kenny McCormack) - 2020-09-17 19:36 +0000
Re: Microsoft Will now support C11 and C17 standard!!!!!!!!!! "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2020-09-17 17:08 -0700
Re: Microsoft Will now support C11 and C17 standard!!!!!!!!!! Bonita Montero <Bonita.Montero@gmail.com> - 2020-09-18 06:11 +0200
Re: Microsoft Will now support C11 and C17 standard!!!!!!!!!! "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2020-09-17 22:38 -0700
Re: Microsoft Will now support C11 and C17 standard!!!!!!!!!! gazelle@shell.xmission.com (Kenny McCormack) - 2020-09-18 10:12 +0000
Re: Microsoft Will now support C11 and C17 standard!!!!!!!!!! Bonita Montero <Bonita.Montero@gmail.com> - 2020-09-18 12:26 +0200
Re: Microsoft Will now support C11 and C17 standard!!!!!!!!!! "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2020-09-18 19:18 -0700
Re: Microsoft Will now support C11 and C17 standard!!!!!!!!!! "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2020-09-18 19:19 -0700
Re: Microsoft Will now support C11 and C17 standard!!!!!!!!!! Bonita Montero <Bonita.Montero@gmail.com> - 2020-09-19 04:21 +0200
Re: Microsoft Will now support C11 and C17 standard!!!!!!!!!! "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2020-09-18 19:28 -0700
Re: Microsoft Will now support C11 and C17 standard!!!!!!!!!! Ben Bacarisse <ben.usenet@bsb.me.uk> - 2020-09-17 16:53 +0100
Re: Microsoft Will now support C11 and C17 standard!!!!!!!!!! already5chosen@yahoo.com - 2020-09-17 16:28 -0700
Re: Microsoft Will now support C11 and C17 standard!!!!!!!!!! Ben Bacarisse <ben.usenet@bsb.me.uk> - 2020-09-18 00:46 +0100
Re: Microsoft Will now support C11 and C17 standard!!!!!!!!!! already5chosen@yahoo.com - 2020-09-18 07:31 -0700
Re: Microsoft Will now support C11 and C17 standard!!!!!!!!!! BGB <cr88192@gmail.com> - 2020-09-18 17:53 -0500
Re: Microsoft Will now support C11 and C17 standard!!!!!!!!!! Bart <bc@freeuk.com> - 2020-09-19 01:02 +0100
Re: Microsoft Will now support C11 and C17 standard!!!!!!!!!! Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2020-09-18 17:34 -0700
Re: Microsoft Will now support C11 and C17 standard!!!!!!!!!! BGB <cr88192@gmail.com> - 2020-09-18 20:57 -0500
Re: Microsoft Will now support C11 and C17 standard!!!!!!!!!! Tim Rentsch <tr.17687@z991.linuxsc.com> - 2020-09-18 23:43 -0700
Re: Microsoft Will now support C11 and C17 standard!!!!!!!!!! Bart <bc@freeuk.com> - 2020-09-19 11:01 +0100
Re: Microsoft Will now support C11 and C17 standard!!!!!!!!!! BGB <cr88192@gmail.com> - 2020-09-19 13:33 -0500
Re: Microsoft Will now support C11 and C17 standard!!!!!!!!!! Tim Rentsch <tr.17687@z991.linuxsc.com> - 2020-11-29 00:23 -0800
Re: Microsoft Will now support C11 and C17 standard!!!!!!!!!! James Kuyper <jameskuyper@alumni.caltech.edu> - 2020-09-18 20:53 -0400
Re: Microsoft Will now support C11 and C17 standard!!!!!!!!!! BGB <cr88192@gmail.com> - 2020-09-18 21:38 -0500
Re: Microsoft Will now support C11 and C17 standard!!!!!!!!!! James Kuyper <jameskuyper@alumni.caltech.edu> - 2020-09-18 22:50 -0400
Re: Microsoft Will now support C11 and C17 standard!!!!!!!!!! Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2020-09-18 20:09 -0700
Re: Microsoft Will now support C11 and C17 standard!!!!!!!!!! BGB <cr88192@gmail.com> - 2020-09-18 23:52 -0500
Re: Microsoft Will now support C11 and C17 standard!!!!!!!!!! Tim Rentsch <tr.17687@z991.linuxsc.com> - 2020-09-18 23:42 -0700
Re: Microsoft Will now support C11 and C17 standard!!!!!!!!!! Bonita Montero <Bonita.Montero@gmail.com> - 2020-09-19 06:43 +0200
Re: Microsoft Will now support C11 and C17 standard!!!!!!!!!! Manfred <noname@add.invalid> - 2020-09-18 20:32 +0200
Re: Microsoft Will now support C11 and C17 standard!!!!!!!!!! Bart <bc@freeuk.com> - 2020-09-18 20:06 +0100
Re: Microsoft Will now support C11 and C17 standard!!!!!!!!!! Manfred <noname@add.invalid> - 2020-09-18 22:04 +0200
Re: Microsoft Will now support C11 and C17 standard!!!!!!!!!! Ben Bacarisse <ben.usenet@bsb.me.uk> - 2020-09-18 21:05 +0100
Re: Microsoft Will now support C11 and C17 standard!!!!!!!!!! Bart <bc@freeuk.com> - 2020-09-18 23:05 +0100
Re: Microsoft Will now support C11 and C17 standard!!!!!!!!!! Ben Bacarisse <ben.usenet@bsb.me.uk> - 2020-09-18 23:14 +0100
Re: Microsoft Will now support C11 and C17 standard!!!!!!!!!! Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2020-09-18 14:09 -0700
Re: Microsoft Will now support C11 and C17 standard!!!!!!!!!! Bart <bc@freeuk.com> - 2020-09-18 22:33 +0100
Re: Microsoft Will now support C11 and C17 standard!!!!!!!!!! Tim Rentsch <tr.17687@z991.linuxsc.com> - 2020-09-18 23:20 -0700
Re: Microsoft Will now support C11 and C17 standard!!!!!!!!!! Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2020-09-18 23:44 -0700
Re: Microsoft Will now support C11 and C17 standard!!!!!!!!!! Tim Rentsch <tr.17687@z991.linuxsc.com> - 2020-09-18 23:59 -0700
Re: Microsoft Will now support C11 and C17 standard!!!!!!!!!! Jorgen Grahn <grahn+nntp@snipabacken.se> - 2020-09-19 11:32 +0000
Re: Microsoft Will now support C11 and C17 standard!!!!!!!!!! Tim Rentsch <tr.17687@z991.linuxsc.com> - 2020-09-19 07:37 -0700
Re: Microsoft Will now support C11 and C17 standard!!!!!!!!!! Ben Bacarisse <ben.usenet@bsb.me.uk> - 2020-09-19 12:43 +0100
Re: Microsoft Will now support C11 and C17 standard!!!!!!!!!! Bart <bc@freeuk.com> - 2020-09-19 13:52 +0100
Re: Microsoft Will now support C11 and C17 standard!!!!!!!!!! Bart <bc@freeuk.com> - 2020-09-19 13:58 +0100
Re: Microsoft Will now support C11 and C17 standard!!!!!!!!!! Ben Bacarisse <ben.usenet@bsb.me.uk> - 2020-09-19 19:18 +0100
Re: Microsoft Will now support C11 and C17 standard!!!!!!!!!! Bart <bc@freeuk.com> - 2020-09-19 23:03 +0100
Re: Microsoft Will now support C11 and C17 standard!!!!!!!!!! Ben Bacarisse <ben.usenet@bsb.me.uk> - 2020-09-19 23:54 +0100
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