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From "Paul Smith (JIRA)" <>
Subject [jira] Commented: (LUCENE-467) Use Float.floatToRawIntBits over Float.floatToIntBits
Date Thu, 17 Nov 2005 04:38:28 GMT
    [ ] 

Paul Smith commented on LUCENE-467:

I probably didn't make my testing framework as clear as I should.  Yourkit was setup to use
method sampling (waking up every X milliseconds).  I wouldn't use the 20% as a 'accurate'
figure but suffice to say that improving this method would 'certainly' improve things.  Only
testing the way you have will flush out the correct numbers.

We don't use -server (due to some Linux vagaries we've been careful with -server because of
some stability problems)

> Use Float.floatToRawIntBits over Float.floatToIntBits
> -----------------------------------------------------
>          Key: LUCENE-467
>          URL:
>      Project: Lucene - Java
>         Type: Improvement
>   Components: Other
>     Versions: 1.9
>     Reporter: Yonik Seeley
>     Priority: Minor

> Copied From my Email:
>   Float.floatToRawIntBits (in Java1.4) gives the raw float bits without
> normalization (like *(int*)&floatvar would in C).  Since it doesn't do
> normalization of NaN values, it's faster (and hopefully optimized to a
> simple inline machine instruction by the JVM).
> On my Pentium4, using floatToRawIntBits is over 5 times as fast as
> floatToIntBits.
> That can really add up in something like Similarity.floatToByte() for
> encoding norms, especially if used as a way to compress an array of
> float during query time as suggested by Doug.

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