## Section: Software

### MaPHyS

`MaPHyS` (Massivelly Parallel Hybrid Solver) is a
software package whose proptotype was initially developed in the framework
of the PhD thesis of Azzam Haidar (CERFACS) and futher consolidated thanks
to the ANR-CIS Solstice funding.
This parallel linear solver couples direct and iterative approaches. The underlying idea
is to apply to general unstructured linear systems domain
decomposition ideas developed for the solution of linear systems
arising from PDEs. The interface problem, associated with the so
called Schur complement system, is solved using a block preconditioner
with overlap between the blocks that is referred to as Algebraic
Additive Schwarz.

In the framework of the INRIA technologic development actions; 24 man-month engineer (Yohan Lee-Tin-Yien) have been allocated to this software activity for the 2009-2011 period. The initial software prototype has been completly redesigned in order to enable us to easily interface any sparse direct solvers and develop new preconditioning technique. The first public release of the software is planned eraly 2012. The same software effort has been undertaken for interfacing any graph partitioning tools.

The `MaPHyS` package is very much a first outcome of the research activity
described in Section
3.3 .
Finally, `MaPHyS` is a preconditioner that can be used to speed-up the convergence
of any Krylov subspace method.
We forsee to either embed in `MaPHyS` some Krylov solvers or to release them as
standalone packages, in particular for the block variants that will be some
outcome of the studies discussed in Section
3.3 .