Re: Motion 31: V04.2 Revision of proposed Level 1 text
On 2012-01-27 09:39:36 -0500, Michel Hack wrote:
> Vincent Lef?vre replied to my comments on "round()":
> > There's no default in 754, but 2 different functions:
> > convertToIntegerTiesToEven and convertToIntegerTiesToAway.
>
> Right -- I had forgotten the 754 required explicitly-rounding conversions.
> The current rounding direction applies to arithmetic in general, and to
> RoundToIntegralExact(), and there *is* a default rule for that.
>
> > I wonder what "language's rule for default rounding" means.
>
> Moot point, given the above. I was talking about implicit rounding.
But for rounding to integer, the rounding mode is most often
explicit (i.e. completely specified by the function name),
and for rounding to the nearest integer, how halfway cases
are handled completely depends on the language. Perhaps both
convertToIntegerTiesToEven and convertToIntegerTiesToAway
could be defined in P1788. ECMAScript's round() should be
forgotten as it isn't even symmetric (I wonder why such a
choice has been made).
--
Vincent Lefèvre <vincent@xxxxxxxxxx> - Web: <http://www.vinc17.net/>
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Work: CR INRIA - computer arithmetic / AriC project (LIP, ENS-Lyon)