Added source Matlab code for reference

matlab/linkage/sumCell.m

@@ -0,0 +1,10 @@
+function summat = sumCell(counts)
+nbatches = size(counts,2);
+sumcell = cell(1,nbatches);
+[nalleles, nloci, ninds] = size(counts{1});
+summat = zeros(nalleles, nloci,'uint16');
+for i = 1:nbatches
+    sumcell{i} = uint16(sum(counts{i},3)); % sum as double format.
+    summat = summat + sumcell{i};
+end
+clear counts;