  An integral coefficient matrix determines an integral arrangement of
hyperplanes in R^m. After modulo q reduction, the same matrix determines an
arrangement A_q of "hyperplanes" in Z^m. In the special case of central
arrangements, Kamiya, Takemura and Terao [J. Algebraic Combin., to appear]
showed that the cardinality of the complement of A_q in Z_q^m is a
quasi-polynomial in q. Moreover, they proved in the central case that the
intersection lattice of A_q is periodic from some q on. The present paper
generalizes these results to the case of non-central arrangements. The paper
also studies the arrangement B_m^{[0,a]} of Athanasiadis [J. Algebraic Combin.
Vol.10 (1999), 207-225] to illustrate our results.
