1. Institute of Applied Mathematics (LS III); TU Dortmund University; Vogelpothsweg 87 Dortmund D-44227 Germany
2. Computational Mathematics Dept.; Sandia National Laboratories; P.O. Box 5800 Albuquerque 87185 NM USA
3. Department of Mathematics and Statistics; University of New Mexico; MSC01 1115 Albuquerque NM 87131 USA