Block factorized forms of sparse approximate inverse preconditioners

The Faculty of Informatics is pleased to announce a seminar given by Thomas Huckle

DATE: Tuesday, November 6th, 2012
PLACE: CSCS - Swiss National Supercomputing Centre, Via Trevano 131, 6900 Lugano, Switzerland
TIME: 10.30

ABSTRACT:
In this talk we present new results on block versions of sparse approximate inverse preconditioners M for given sparse matrix A. We consider the Frobenius norm minimization $|| AM-I ||_F$, also in the factorized form. Blocked versions allow a more efficient memory access, and reduce the number of least squares problems that have to be considered in the construction of the preconditioner M. Therefore it is necessary to identify columns of M with similar pattern and combine them  to a larger block. Furthermore, we consider an iterative method for constructing a sequence  of preconditioners  $AM_1M_2...M_k$ by identifying columns in $||AM-I||_F$ with large residual and improving the preconditinoer only relative to these columns.Numerical examples show the effectiveness of these new methods.

BIO:
Thomas Huckle is Professor for Computer Science and Mathematics at the TU Muenchen since 1995. He graduated at the University Wuerzburg 1985, with longer research stays at Stanford (1993-94), UCLA (2000-01), and Leeds University (2006).

HOST: Prof. Olaf Schenk