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Posted to dev@commons.apache.org by Gilles Sadowski <gi...@harfang.homelinux.org> on 2010/05/06 14:09:17 UTC
[Math] NaN in "equals"
Hello.
In the "MathUtils" class, "equals" methods consider that a NaN is equal to a
NaN. It seems that the orthodox view is that such a comparison should return
"false".
Is there a rationale behind the current behaviour (e.g. it is admittedly
more efficient to not call "Double.isNaN")?
Or can I make the changes in order to comply to IEEE?
Best,
Gilles
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Re: [Math] NaN in "equals"
Posted by Bill Barker <bi...@verizon.net>.
--------------------------------------------------
From: "Gilles Sadowski" <gi...@harfang.homelinux.org>
Sent: Thursday, May 06, 2010 5:09 AM
To: <de...@commons.apache.org>
Subject: [Math] NaN in "equals"
> Hello.
>
> In the "MathUtils" class, "equals" methods consider that a NaN is equal to
> a
> NaN. It seems that the orthodox view is that such a comparison should
> return
> "false".
> Is there a rationale behind the current behaviour (e.g. it is admittedly
> more efficient to not call "Double.isNaN")?
> Or can I make the changes in order to comply to IEEE?
>
Well, that is the convention in most of the library, so would be -1 to
changing it only in MathUtils since it would then be inconsistent (e.g.
ArrayRealVector.equals returns "true" if both vectors have a NaN in some
(not necessarily the same) position. I would be -0.5 to changing it in a
point release, since there may be users that are relying on the current
behavior and point releases are supposed to be drop in replacements. I
don't have strong feelings either way for the next major release.
>
> Best,
> Gilles
>
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