asymptotic behaviour of coefficients in nonnegative matrix iteration Let $A$ be a square matrix with nonnegative integer coefficients.
Is there a simple way to prove that there is a "period" $d$ such that for all $0\leq r<d$, the coefficient $a_{i,j,n}$ at position $(i,j)$ in the matrix $A^{nd+r}$ is asymptotically (with respect to $n$) equivalent to $x n^y z^n$, where $x,y,z$ are nonnegative constants depending on $i,j,d,r$.
The period is needed to avoid oscillating behaviours like $(-1)^n$, or cycles of bigger length.
I found this paper which should help, but I'm having trouble formalizing a proof: http://www.ams.org/journals/jams/2000-13-04/S0894-0347-00-00342-8/S0894-0347-00-00342-8.pdf).
 A: For a primitive matrix $A$, $A = ||a_{i j}||$ (the one that has a single eigenvalue with maximum modulo) you can use a Perron's formula for elements of matrix $A^m$, $A^m = ||a_{ij}^{<m>}||$:
\begin{equation*}
a^{<m>}_{i j} = \sum_{h = 1}^\nu \frac{1}{(n_h - 1)!}
    \biggl[\frac{d^{n_h-1}}{d\lambda^{n_h-1}}
    \biggl(\frac{\lambda^m A_{i j}(\lambda)}{\Psi_h(\lambda)} \biggr)
        \biggr]_{\lambda = \lambda_h},
\end{equation*}
where $A(\lambda) = |\lambda E - A|$; $\lambda_1, \dots, \lambda_\nu$ are roots of the matrix characteristic equation $A(\lambda) = 0$ of multiplicities $n_1, \dots, n_\nu$ respectively; $A_{i j}(\lambda)$ is an algebraic adjunct for the element $\lambda \delta_{i j} - a_{i j}$ in determinant $A(\lambda)$; $\Psi_h = A(\lambda) \cdot (\lambda - \lambda_h)^{-n_h}$.
If $A$ is an imprimitive matrix $A$ with index of imprimitivity $h$, then $A^h$ splits into $h$ primitive matrices with the same maximum eigenvalue: $A^h = \operatorname{diag} \{ A_1, \dots, A_h\}$. In this case you can use the same formula for matrices $A^{mh}$.
Perron's formula is a well known formula and can be found for instance in the book Gantmacher F.R. The Theory of Matrices, 1960, volume 1, page 116, formula (23') and a note for it. The proof of the statement about imprimitive matrices can be found in the same book volume 2 at page 82. There is a link for the book: Gantmacher F.R. The Theory of Matrices.
