11 Jul
2007
11 Jul
'07
2:57 p.m.
ajb@spamcop.net wrote:
G'day all.
Andrew Coppin wrote:
Actually, LZW works surprisingly well for such a trivial little algorithm... When you compare it to the complexity of an arithmetic coder driven by a high-order adaptive PPM model (theoretically the best general-purpose algorithm that exists), it's amazing that anything so simple as LZW should work at all!
Not really. LZW is basically PPM with a static (and flat!) frequency prediction model. The contexts are build in a very similar way.
Yes - but making it use a non-flat model opens a whole Pandora's Box of fiddly programming. ;-) (It's not "hard" as such - just frustratingly fiddly to get correct...)