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Jason Davies 2011-09-04 18:30:37 +01:00
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@ -2,10 +2,15 @@ Bloom Filter
============
This JavaScript bloom filter implementation uses the non-cryptographic
[Fowler–Noll–Vo hash function][1] for speed. In fact, the hash function only
needs to be called once per operation, as *n* hash functions can be simulated
using only two hash functions. And two 32-bit hash functions can be simulated
[using a single 64-bit hash function][2]!
[Fowler–Noll–Vo hash function][1] for speed.
Although the bloom filter requires *n* hash functions, we can simulate this
using only *two* hash functions. In fact, we cheat and get the second hash
function almost for free by iterating once more on the first hash using the FNV
hash algorithm.
Thanks to Will Fitzgerald for his [help and inspiration][2] with the hashing
optimisation.
[1]: http://isthe.com/chongo/tech/comp/fnv/
[2]: http://willwhim.wordpress.com/2011/09/03/producing-n-hash-functions-by-hashing-only-once/