We consider large, sparse linear systems
that result from the discretization of partial
differential equations on regular and ir
regular domains, and we focus on the ap
plication of the preconditioned conjugate
gradient (PCCG) method to the solution of
such systems. More specifically, our goal
is the efficient implementation of the
PCCG method on vector supercomputers.
The contribution to the above goal is
made by the introduction of a data struc
ture that can be effectively manipulated on
vector machines, the utilization of precon
ditioning matrices obtained by incomplete
factorization with diagonal update sets,
and the introduction of new numbering
schemes for both regular and irregular
grids.