Fraunhofer-Chalmers Research Centre for Industrial Mathematics, Gothenburg, Sweden. henning@fcc.chalmers.se|Fraunhofer-Chalmers Research Centre for Industrial Mathematics, Gothenburg, Sweden. henning@fcc.chalmers.se|Fraunhofer-Chalmers Research Centre for Industrial Mathematics, Gothenburg, Sweden. henning@fcc.chalmers.se|Fraunhofer-Chalmers Research Centre for Industrial Mathematics, Gothenburg, Sweden. henning@fcc.chalmers.se