Math.round(...) and bug 6430675

Brian Burkhalter brian.burkhalter at
Sat Feb 2 01:19:43 UTC 2013

Hi Jeff,

Based on my tests it looks as if you are correct about the behavior. Would you mind filing an issue so that this may be tracked?



On Jan 31, 2013, at 1:26 PM, Jeff Hain wrote:

> Hi.
> Since 6430675 fix, Math.round(float) and Math.round(double)
> specs no longer specify rounding by adding 0.5 and then using floor,
> and let the user believe that they "now round up properly".
> However playing with fresh JDK 7 and 8 versions I saw that
> these methods still exhibit some suprising results coming
> from adding 0.5 and then using floor.
> For example, for odd values in [8388609.0f,16777215.0f] or
> [-16777215.0f,-8388609.0f], which are mathematical integers,
> Math.round(float) returns value+1.
> Shouldn't the references to floor(value+0.5(f/d)) be restored
> in the specs, or the implementations having a work-around for
> these cases?
> -Jeff

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