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amg4psblas/README

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This directory contains the MLD2P4 set of preconditioners, version 2.1
WHAT'S NEW
Version 2.1
1. The multigrid preconditioner now include fully general V- and W-
cycles. We also support K-cycles, intended to be used in
conjunction with Flexible CG available in PSBLAS 3.5.
2. The smoothers now include popular
variants such as Jacobi, forward and backward hybrid
Gauss-Seidel (intra-process Gauss-Seidel, inter-process
block-Jacobi).
3. The PRE and POST specification for smoothers can now be
specified independently of each other: you can even specify
different smoothers for PRE and POST (e.g. forward Gauss-Seidel
PRE with backward Gauss-Seidel POST). The default is to
have the specs apply to both PRE and POST.
Version 2.0.
Finally moved to F2003, with the support of PSBLAS3.
There are a few minor differences at user level:
1. In the configure step, you should specify the INSTALL directory
of PSBLAS version 3.4, not the source directory;
2. In the various makefiles, libmld_prec.a should now be used in
addition (and in front of) libpsb_prec.a, and no longer in
place of it.
3. As for the basic usage, this is practically identical to the
previous version(s).
You should use the same MPI/serial compilers that were used for the
PSBLAS installation.
The Fortran 2003 support means that it is far easier to develop and
integrate new solvers and smoothers; you need to take one of the
existing solvers/smoothers as a model, develop your own by
changing/replacing the model contents, and then pass the new object
to the PREC%SET() method which will copy into the internals, as per
the PROTOTYPE design pattern. Take a look at the test/newslv
directory to see an example. It's easier done than said!
Versions known to work:
UMFPACK: 5.4
SuperLU: 4.3 and 5.0
SuperLU_Dist: 3.3 and 4.2
Note that with SuperLU_Dist you will probably need to add further
link options, e.g. the ParMetis library or the openmp runtime;
you can do this using the configure option --with-extra-libs
In version 1.1:
- The MLD_SIZEOF() function has been redefined to be INTEGER(8), so
as to be able to measure large data sets.
- The internals of the multilevel preconditioner have been repackaged
in a more structured fashion; no changes are needed in the user
code.
- Note that we now need version 2.3.1 of PSBLAS.
To compile:
0. Unpack the tar file in a directory of your choice (preferrably
outside the main PSBLAS directory).
1. run configure --with-psblas=<ABSOLUTE path of the PSBLAS install directory>
adding the options for SuperLU, SuperLU_Dist, UMFPACK as desired.
2. Tweak Make.inc if you are not satisfied.
3. make;
4. Go into the test subdirectory and build the examples of your choice.
Notes:
- The single precision version is supported only by SuperLU; thus, even
if you specify at configure to use UMFPACK or SuperLU_Dist, the
corresponding preconditioner options will be available only from the
double precision version.
- A program that was using the PSBLAS precoditioners needs no source
code changes, but should be recompiled. If the new preconditioner
(or preconditioner options, such as ILU(N) factorization) are
required, only the type of the preconditioner object and its
setup/build/free calls should be updated; the rest of the
application continues to make use of the PSBLAS existing
interfaces.
CREDITS
developed by
Salvatore Filippone
Pasqua D'Ambra
Daniela di Serafino
Alfredo Buttari