Daniel@0: function C = mysymsetdiff(A,B)
Daniel@0: % MYSYMSETDIFF Symmetric set difference of two sets of positive integers (much faster than built-in setdiff)
Daniel@0: % C = mysetdiff(A,B)
Daniel@0: % C = (A\B) union (B\A) = { things that A and B don't have in common }
Daniel@0: 
Daniel@0: if isempty(A)
Daniel@0:   ma = 0;
Daniel@0: else
Daniel@0:   ma = max(A);
Daniel@0: end
Daniel@0: 
Daniel@0: if isempty(B)
Daniel@0:   mb = 0;
Daniel@0: else
Daniel@0:   mb = max(B);
Daniel@0: end
Daniel@0: 
Daniel@0: if ma==0 
Daniel@0:   C = B;
Daniel@0: elseif mb==0
Daniel@0:   C = A;
Daniel@0: else % both non-empty
Daniel@0:   m = max(ma,mb);
Daniel@0:   bitsA = sparse(1, m);
Daniel@0:   bitsA(A) = 1;
Daniel@0:   bitsB = sparse(1, m);
Daniel@0:   bitsB(B) = 1;
Daniel@0:   C = find(xor(bitsA, bitsB));
Daniel@0: end