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From "Anton Luht" <anton.l...@gmail.com>
Subject [optimization] Algorithmic tricks
Date Tue, 25 Jul 2006 10:18:57 GMT
Hello,

I'd like to suggest people that know some algorithmic tricks to look
at the corresponding areas of classlib. Maybe some of the community
members had (un)lucky experience of tuning performance of some
application that led them to a deep knowledge of some very specific
area has good approaches but not too widely known to an average
developer. It might also be an interest for students and other people
from institutes and universities.

What I'm talking about is not related to 'premature optimization' that
is now being discussed in another thread but something very narrow,
limited to maybe one method and not influencing anything else.

For example, consider current implementation of
java.util.BitSet.cardinality() . It just checks all bits one by one
and increments count. [1] Gives an overview of algorithms for checking
set bit count. The fastest algorithms are with table lookup, which
requires additional memory, but there are algorithms that are several
times faster than iteration (in C) and don't require tables. I believe
such local optimizations with good comments and links to corresponding
resources won't do any harm and are a good point to start with.

Does it make sence?

[1] http://www-db.stanford.edu/~manku/bitcount/bitcount.html

-- 
Regards,
Anton Luht,
Intel Middleware Products Division

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