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