Re: [patch] rint.3: Document that halfway cases are rounded to even.

On Thu, Mar 12, 2015 at 5:43 PM, Matt Turner [off-list ref] wrote:

Per IEEE-754 rounding rules.

The round(3) page describes the behavior of rint and nearbyint in the
halfway cases by saying:

   These functions round x to the nearest integer, but round halfway
   cases away from zero [...], instead of to the nearest even integer
   like rint(3)

Signed-off-by: Matt Turner <redacted>
---

Sorry, this is not precise -- these functions round halfway cases to
nearest even when the rounding mode is set to round-to-nearest. I'll
send a revised patch.

And for what it's worth, as far as I can tell this rounding behavior
(halfway cases round to nearest even) is defined by IEEE-754 and not
the C language spec. I don't know if that's worth mentioning.
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