NumericUtils.floatToSortableInt does not sort certain NaN ranges correctly.
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Key: LUCENE-3582
URL: https://issues.apache.org/jira/browse/LUCENE-3582
Project: Lucene - Java
Issue Type: Bug
Reporter: Dawid Weiss
Priority: Trivial
Fix For: 4.0
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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