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https://issues.apache.org/jira/browse/LUCENE-3582?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13153200#comment-13153200
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Dawid Weiss commented on LUCENE-3582:
-------------------------------------
Ok, don't fix it then, no problem from me -- like I said, I only found out
because I looked inside. It's not a bug, it's a feature ;)
I personally think utility methods should work correctly for all kinds of input
-- that utility method in NumericUtils should at least say it doesn't support
NaN (or better: assert so).
> NumericUtils.floatToSortableInt does not sort certain NaN ranges correctly.
> ---------------------------------------------------------------------------
>
> Key: LUCENE-3582
> URL: https://issues.apache.org/jira/browse/LUCENE-3582
> Project: Lucene - Java
> Issue Type: Bug
> Reporter: Dawid Weiss
> Assignee: Uwe Schindler
> Priority: Trivial
> Fix For: 4.0
>
> Attachments: LUCENE-3582.patch
>
>
> The current implementation of floatToSortableInt does not account for
> different NaN ranges which may result in NaNs sorted before -Infinity and
> after +Infinity. The default Java ordering is: all NaNs after Infinity.
> A possible fix is to make all NaNs canonic "quiet NaN" as in:
> {code}
> // Canonicalize NaN ranges. I assume this check will be faster here than
> // (v == v) == false on the FPU? We don't distinguish between different
> // flavors of NaNs here (see http://en.wikipedia.org/wiki/NaN). I guess
> // in Java this doesn't matter much anyway.
> if ((v & 0x7fffffff) > 0x7f800000) {
> // Apply the logic below to a canonical "quiet NaN"
> return 0x7fc00000 ^ 0x80000000;
> }
> {code}
> I don't commit because I don't know how much of the existing stuff relies on
> this (nobody should be keeping different NaNs in their indexes, but who
> knows...).
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