===affil2:

===firstname:
Iain S
===firstname4:

===firstname3:

===lastname2:

===lastname:
Duff
===firstname5:

===affil6:

===lastname3:

===email:
iain.duff@stfc.ac.uk
===lastname6:

===affil5:

===otherauths:

===lastname4:

===affil4:

===lastname7:

===affil7:

===firstname7:

===postal:
Rutherford Appleton Laboratory
Chilton
Didcot
Oxon OX11 9LN
UK
===firstname6:

===ABSTRACT:
I first used the term hybrid methods in 1989 to mean a solution technique that
combined a direct solver with an iterative technique to solve sparse linear
systems.  I view this as a way of extending the use of direct methods to
larger problems and will argue how this differs from the iterative
concept of preconditioning.

I will then talk a little about some recent work in Toulouse on rehabilitating
the block Cimmino method, an archetypical hybrid method.
===affil3:

===lastname5:

===affilother:

===title:
Hybrid methods for the solution of large sparse linear equations
===firstname2: