Re: [patch,complex] Replace hard-coded constants

[Eric Blake <eblake at redhat dot com>]

On 11/29/2010 08:32 AM, Howland Craig D (Craig) wrote:
> http://www.opengroup.org/onlinepubs/9699919799/functions/tan.html
>>> So why is that missing in the descriptions of the complex
>>> functions?
> 
> Annex G of the C standard (ISO/IEC 9899), "IEC 60559-compatible complex
> arithmetic," does specify return values for exceptional conditions.
> Since Newlib nominally generally does support 60559 (better known as
> IEEE 754), these are a good way to go.  And they are not vague.  (I
> don't know why POSIX does not take a moment to mention them,  but given
> their deferral to the C standard, POSIX implicitly requires them when
> 60559 is used.)

POSIX uses <MX> shading for constructs required by Annex G of the C
standard, and <MXX> shading for additional constructs required by POSIX
but not by C Annex G if IEC 60559 is in effect.  Compliance with IEC
60559 is not required for POSIX compliance (that is, complying with
<MX>/<MXX> shading is an optional implementation choice), but is a good
idea to shoot for, especially for non-embedded uses of newlib.

If you have concrete examples of something that should be in POSIX but
is currently missing, it would be a good idea to raise that as a defect
in the POSIX standard to get that situation corrected.  Unfortunately, I
haven't been following this thread closely enough myself to take on the
task.

-- 
Eric Blake   eblake@redhat.com    +1-801-349-2682
Libvirt virtualization library http://libvirt.org

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