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Re: huffmandict: Matlab compatibility, Matlab bugs..
From: |
Simon Persson |
Subject: |
Re: huffmandict: Matlab compatibility, Matlab bugs.. |
Date: |
Thu, 5 Oct 2006 22:34:58 +0200 |
User-agent: |
KMail/1.9.4 |
On Thursday 05 October 2006 21:59, Muthiah Annamalai wrote:
> 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?
>
Maybe someone wants to estimate probabilites from a smaller sample than the
full data to be encoded. Then codes for all symbols are still needed even if
they don't occur in the analysed sample. That's the only reason I can think
of.
Simon
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