In a similar fashion, B = B,@ B, on H = H,$ H,. From T = AB, we have T, = A,B, and T, = A,B,. Since Tl is invertible, A, and B, are both positive. Thus Tl is similar to a positive matrix by the proof of (2) j (3). On the other hand, since the nilpotent T2 is the product of the nonnegative matrices A, and B,, we infer from Lemma 2.1 that T, = 0.
Therefore T = T,@ 0 is similar to a nonnegative matrix.