Mercurial > hg > camir-aes2014
comparison toolboxes/FullBNT-1.0.7/KPMtools/entropy.m @ 0:e9a9cd732c1e tip
first hg version after svn
author | wolffd |
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date | Tue, 10 Feb 2015 15:05:51 +0000 |
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-1:000000000000 | 0:e9a9cd732c1e |
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1 function H = entropy(v, scale) | |
2 % ENTROPY Entropy log base 2 | |
3 % H = entropy(v) | |
4 % If v is a matrix, we compute the entropy of each column | |
5 % | |
6 % % H = entropy(v,1) means we scale the result so that it lies in [0,1] | |
7 | |
8 if nargin < 2, scale = 0; end | |
9 | |
10 v = v + (v==0); | |
11 H = -1 * sum(v .* log2(v), 1); % sum the rows | |
12 | |
13 if scale | |
14 n = size(v, 1); | |
15 unif = normalise(ones(n,1)); | |
16 H = H / entropy(unif); | |
17 end |