ASCEND: dynamic modelling improvements

by Ksenija Bestuzheva for Python Software Foundation

There are models with variable structure which are currently not supported by ASCEND. These are, for example, models with hysteresis or with complex boundary conditions. More generally, they have not only region behavior (for which ASCEND has WHEN statements), but also boundary behavior: some actions should be performed exactly at the boundaries. After thinking over the problem I made a conclusion that there are two main types of actions: solving systems of boundary equations and assigning values to some variables. In order to implement this ASCEND needs new syntax and new solver behavior.