What is a multirate array?

Multirate arrays (MRAs) are an extension of systolic arrays where different data variables are propagated with different clocks. Recently, synthesis methods for MRA synthesis, starting from Affine Recurrence Equations (AREs) have been proposed. In this paper we give a formal definition of MRAs as systems of Uniform Recurrence Equations (UREs) defined over sparse polyhedral domains. We then show a direct equivalence between the previously proposed synthesis methods and a simple index transformation of sparse UREs.