Waveform relaxation relies critically on the partitioning of the system of ODEs being integrated. If the partitioning is successful, very few relaxations are needed. On the other hand, if the partitioning is less successful, a large number of iterations is needed or the relaxation may even be divergent.

This talk presents partitioning techniques which permit the use of just one or two relaxation iterations in the decoupled integration formula underlying a WR method. The decoupled integration formula does not use a waveform but advances point wise. The savings in relaxation iterations therefore come at the cost of less efficient multirate implementation - if any at all - and finer grained parallelity.

The partitioning techniques and decoupled implicit integration formulas will be demonstrated for chemical reaction equations in air pollution models and for digital electrical circuits.

MINISIMPOSIUM SESSION: 18. Waveform Relaxation Techniques