wolffd@0: function H = entropy(v, scale)
wolffd@0: % ENTROPY Entropy log base 2
wolffd@0: % H = entropy(v)
wolffd@0: % If v is a matrix, we compute the entropy of each column
wolffd@0: %
wolffd@0: % % H = entropy(v,1) means we scale the result so that it lies in [0,1]
wolffd@0: 
wolffd@0: if nargin < 2, scale = 0; end
wolffd@0: 
wolffd@0: v = v + (v==0);
wolffd@0: H = -1 * sum(v .* log2(v), 1); % sum the rows
wolffd@0: 
wolffd@0: if scale
wolffd@0:   n = size(v, 1);
wolffd@0:   unif = normalise(ones(n,1));
wolffd@0:   H = H / entropy(unif);
wolffd@0: end