Adam and Kevin have been working on a revision of the reference semantics for Acumen. The revision ensures that the order in which continuous assignment statements occur in (a particular scope of) an Acumen model does not affect the simulation results. This was achieved by delaying updates to the state until after all evaluations for a particular continuous step have been performed. A consequence of this change is that the method used to solve ODEs (in particular, the transformation from higher-order ODEs to systems of first-order ODEs) introduces delays in the solutions which did not occur in the previous formulation of the reference semantics.
