find out the neighbour matrix of a mesh

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%finding neighbour%%%%%%%%%%%%%%%%%%%%%%%%%%%%
neighbour_matrix = zeros(n,n);
for i=1:n
neighbour = find(F(:,1)==i | F(:,2)==i | F(:,3)==i);
neighbour = F(neighbour,:);
neighbour = setdiff(neighbour(:),i);
neighbour_matrix(i,neighbour(:)) = ones(1,size(neighbour,2));
end