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Re: AArch64 patches for glibc master.


On Mon, 9 Dec 2013, Carlos O'Donell wrote:

> Is this requirement because IEC 60559 requires everything to be correctly
> rounded, therefore if C11 defines sqrt in terms of the IEC 60559 operation
> then the function itself must be correctly rounding as required by the
> standard (IEEE Std 754-2008)?

Yes.

I believe TS 18661-4, providing C bindings to additional functions from 
IEEE 754-2008, will distinguish between the (optional) correctly-rounding 
functions bound to the "Recommended correctly rounded functions" in IEEE 
754-2008 Table 9.1, and functions providing approximations that need not 
be correctly rounded (so, for example, exp will remain as a function 
providing an approximation, crexp will be reserved for a correctly 
rounding version; rsqrt will be added for an approximation to reciprocal 
square root and crrsqrt will be reserved for a correctly rounding 
version).  (No public draft of parts 4 or 5 of this TS is yet available, 
but there's an old summary of plans at 
<http://www.open-std.org/jtc1/sc22/wg14/www/docs/n1582.pdf>.)

-- 
Joseph S. Myers
joseph@codesourcery.com


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