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huffmandict: Matlab compatibility, Matlab bugs..


From: Muthiah Annamalai
Subject: huffmandict: Matlab compatibility, Matlab bugs..
Date: Thu, 05 Oct 2006 14:59:09 -0500

Hi there,
Im trying to write some functions in Matlab communication toolbox
(source coding functions) for Octave forge.

While I was doing that, I came across a funny bug in Matlab.

Huffman encoding is done in 2 steps (according to Matlab), 
and the first step generates dictionary. 
Essentially all Huffman coding does it map low probability symbols
to long codewords and vice-verca.

 So the wierd thing (in Matlab impl) is that for 0-probability symbols
have long code words assigned to them. I wonder... why someone will  
infact even have a zero probability symbols occur in their data?

A conceptual error of the user is magnified in the matlab implementation
and it assigns long really long codewords to 0 prob' symbols.
Im just assigning an empty matrix to that, which I think is logical.

try the code using Octave forge functions(CVS) & matlab.

prob=[0.5 0 0.3 0.2 0];
x=huffmandict(1:5,prob);
x{:}

What do you think? 

Thanks
Muthu
        



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