Institute for Algorithms and Scientific Computing (SCAI), Fraunhofer Gesellschaft, Schloss Birlinghoven, 53754 Sankt Augustin, Germany.|Institute for Algorithms and Scientific Computing (SCAI), Fraunhofer Gesellschaft, Schloss Birlinghoven, 53754 Sankt Augustin, Germany.|Institute for Algorithms and Scientific Computing (SCAI), Fraunhofer Gesellschaft, Schloss Birlinghoven, 53754 Sankt Augustin, Germany.