The simulation of technical systems involve more and more
refined models. Dealing with highly  integrated circuits
one encounters the phenomenon of latency. Therefore coupled
settings arise fairly natural, where subdivisions are
characterised by largely differing time constants.
In order to have an efficient algorithm for integration,
one can think of adapting the numerics to the activity level
of the units. A bunch of approaches has been developed,
which bases on splitting on various levels.
Here we pursue the multirate step size approach: the set of
state variables is decomposed into a latent and an active part,
which are integrated by using at the same time a macro step for
the latent components and a number of micro steps for the active
ones. Hence the main part of the method is to answer the question,
how to compute the coupling variables.
After an introduction to circuit simulation we start from the
original type of the multirate Rosenbrock-Wanner method and come
to the discussion of generalised and mixed type multirating,
which again are ROW-based.

---

Helge Holden <holden@math.ntnu.no>

2000-08-30 11:38