isempty(find(X)) --> isempty(find(X,1))
isempty(find(X)) --> isempty(find(X,1))

mlint complains about this construct as being slow, so replacing with
something faster.

matlab2tikz/matlab2tikz,nidrosianDeath/matlab2tikz,okomarov/matlab2tikz,okomarov/matlab2tikz,egeerardyn/matlab2tikz,LJeub/matlab2tikz,egeerardyn/matlab2tikz,miscco/matlab2tikz,RPeschke/matlab2tikz,PeterPablo/matlab2tikz,matlab2tikz/matlab2tikz