“…As a result, model order reduction techniques have been applied to dramatically reduce the dimension and the complexity of the resulting system of ODEs, see e.g., [9,53,26,44,25,27,30]. In particular, the common approach is to form a lexicographic ordering of the spatial nodes, unrolling the arrays (i.e., matrices or tensors when d = 2 and d = 3 respectively) of nodal values into long vectors in R N , i.e., the unknown vectors u i (t) ∈ R N .…”