User blog comment:Nayuta Ito/Highly Nested Function/@comment-26428969-20151024084338/@comment-26428969-20151024110443

you changed it, good,  but now HNF(1,1) = HNF(0,HNF(1,0)) = HNF(0,2) = ????

The problem is that it cannot reduce to arrays with LESS entries, because the right entries never decreases!

my proposition: HNF(0,0,...,0,0,A) = HNF(A), i.e. delete leftmost 0s which do not success to any non-0 entry