comparison toolboxes/FullBNT-1.0.7/KPMtools/logsumexp.m @ 0:e9a9cd732c1e tip

first hg version after svn

+function s = logsumexp(a, dim)
+% Returns log(sum(exp(a),dim)) while avoiding numerical underflow.
+% Default is dim = 1 (rows) or dim=2 for a row vector
+% logsumexp(a, 2) will sum across columns instead of rows
+
+% Written by Tom Minka, modified by Kevin Murphy
+
+if nargin < 2
+  dim = 1;
+  if ndims(a) <= 2 & size(a,1)==1
+    dim = 2;
+  end
+end
+
+% subtract the largest in each column
+[y, i] = max(a,[],dim);
+dims = ones(1,ndims(a));
+dims(dim) = size(a,dim);
+a = a - repmat(y, dims);
+s = y + log(sum(exp(a),dim));
+%i = find(~finite(y));
+%if ~isempty(i)
+%  s(i) = y(i);
+%end