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From Yonik Seeley <ysee...@gmail.com>
Subject Re: Float.floatToRawIntBits
Date Wed, 16 Nov 2005 22:11:36 GMT
Wow!  A much larger gain than I expected!
Thanks for the profile Paul!

-Yonik
Now hiring -- http://forms.cnet.com/slink?231706


On 11/16/05, Paul Smith <psmith@aconex.com> wrote:
> I can confirm this takes ~ 20% of an overall Indexing operation (see
> attached link from YourKit).
>
> http://people.apache.org/~psmith/luceneYourkit.jpg
>
> Mind you, the whole "signalling via IOException" in the
> FastCharStream is a way bigger overhead, although I agree much harder
> to fix.
>
> Paul Smith
>
> On 17/11/2005, at 7:21 AM, Yonik Seeley wrote:
>
> > 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.
> >
> > -Yonik
> > Now hiring -- http://forms.cnet.com/slink?231706
> >
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