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From "Doug Cutting (JIRA)" <j...@apache.org>
Subject [jira] Commented: (LUCENE-467) Use Float.floatToRawIntBits over Float.floatToIntBits
Date Thu, 17 Nov 2005 18:23:41 GMT
    [ http://issues.apache.org/jira/browse/LUCENE-467?page=comments#action_12357917 ] 

Doug Cutting commented on LUCENE-467:
-------------------------------------

How fast can you make:

public byte floatToByte(float f, int numMantissaBits);

?

That would be more reusable, and shouldn't be much slower...


> Use Float.floatToRawIntBits over Float.floatToIntBits
> -----------------------------------------------------
>
>          Key: LUCENE-467
>          URL: http://issues.apache.org/jira/browse/LUCENE-467
>      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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