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Re: [RFC] How to add vector math functions to Glibc
- From: Andrew Senkevich <andrew dot n dot senkevich at gmail dot com>
- To: "Joseph S. Myers" <joseph at codesourcery dot com>
- Cc: Christoph Lauter <christoph dot lauter at lip6 dot fr>, "Carlos O'Donell" <carlos at redhat dot com>, libc-alpha <libc-alpha at sourceware dot org>
- Date: Fri, 10 Oct 2014 17:27:03 +0400
- Subject: Re: [RFC] How to add vector math functions to Glibc
- Authentication-results: sourceware.org; auth=none
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2014-10-09 21:45 GMT+04:00 Joseph S. Myers <joseph@codesourcery.com>:
>> +/* General constants:
>> + * lAbsMask
>> + */
>
> I really don't think these comments are sufficient to explain the
> semantics of the values. I'm expecting comments of the form "the
> following N 64-bit values are IEEE binary64 constants a[0], a[1], ... for
> a minimax polynomial expansion a[0] + a[1]x + a[2]x^2 + ... of
> cos(x+0.125) for x in the interval [0.125,0.25]" or similar - an
> unambiguous description of exactly what the values mean / how they are
> used.
Table values were obtained mostly through many years of research and
experimental work, were part of old enough codes and we have no
detailed comments there either. So our proposal is to stay at current
level of comments as these codes proved their correctness and
effectiveness through many years of intensive usage in math
applications in such institutions as CERN, LLNL, etc.
> And see my previous point about defining macros for the offsets in
> this table in such a way that build errors will occur if the macro values
> are wrong.
We will follow-up, though these sources will not change often and they
have no influence on usage value.
--
WBR,
Andrew