Java 8 RFR 8010430: Math.round has surprising behavior for odd values of ulp 1

[Dmitry Nadezhin]

The specification of java.lang.Math.round() says
    * Returns the closest {@code int} to the argument, with ties
     * rounding up.

It is not clarified what is "ties rounding up".
I guess that it should correspond to the direction "roundTiesToAway" of
IEEE 754-2008
and to the java.math.RoundingMode.HALF_UP .

They round
+0.5 -> +1
-0.5 -> -1

The current implementation of java.lang.Math.round() rounds
+0.5 -> +1
-0.5 -> 0

"ties rounding up" should match IEEE754 standard and other JDK math class,
shouldn't it ?


On Fri, Aug 23, 2013 at 10:32 PM, Brian Burkhalter <
brian.burkhalter at oracle.com> wrote:

> This message follows the RFC
> http://mail.openjdk.java.net/pipermail/core-libs-dev/2013-August/019560.htmlposted on August 2.
>
> The issue is http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=8010430.
>
> The proposed patch http://cr.openjdk.java.net/~bpb/8010430/ has the
> effect of option (A) in the aforementioned RFC.
>
> Thanks,
>
> Brian