RAL 95 - 026 On approximate - inverse preconditioners

We investigate the use of sparse approximate-inverse preconditioners for the iterative solution of unsymmetric linear systems of equations. Such methods are of particular interest because of the considerable scope for parallelization. We propose a number of enhancements which may improve their performance. When run in a sequential environment, these methods can perform unfavourably when compared with other techniques. However, they can be successful when other methods fail and simulations indicate that they can be competitive when considered in a parallel environment. 1 Current reports available by anonymous ftp from joyous-gard.cc.rl.ac.uk (internet 130.246.9.91) in the directory “pub/reports”. Computing and Information Systems Department, Atlas Centre, Rutherford Appleton Laboratory, Oxfordshire OX11 0QX, England.