This file is part of AGMG software package,
Release 3.1.2 built on "Jan 17 2012"

   AGMG is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation, either version 3 of the License, or
   (at your option) any later version.

   AGMG is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with AGMG.  If not, see <http://www.gnu.org/licenses/>.

Up-to-date copies of the AGMG package can be obtained
from the Web pages <http://homepages.ulb.ac.be/~ynotay/AGMG>.

You can acknowledge, citing references [1] [2], and [3], the contribution
of this package in any scientific publication dependent upon it use.

 [1] Y. Notay, An aggregation-based algebraic multigrid method,
    Electronic Transactions on Numerical Analysis, vol. 37, pp. 123-146, 2010

 [2] A. Napov and Y. Notay, An algebraic multigrid method with guaranteed
    convergence rate, to appear in SIAM J. Sci. Comput., 2012.

 [3] Y. Notay, Aggregation-based algebraic multigrid for convection-diffusion
    equations, Report GANMN 11-01, Universite Libre de Bruxelles, Brussels,
    Belgium, 2011.

See the accompanying userguide for more details on how to use the software,
and the README file for installation instructions.

AGMG Copyright (C) 2011 Yvan NOTAY

You read this file because you have successfully downloaded and
uncompress the package.

Assumed you did this in directory /MYDIR
(for instance, your home directory)
This created a directory /MYDIR/AGMG_3.1.2 and the present file is
/MYDIR/AGMG_3.1.2/README

You will find the documentation in /MYDIR/AGMG_3.1.2/Doc/
(a userguide giving additional information and the papers referred above).

Fortran 90
----------

The userguide refers to two examples (one sequential and one parallel).
The related sources are located in /MYDIR/AGMG_3.1.2/Example_seq/
and /MYDIR/AGMG_3.1.2/Example_par/, respectively. There you will find also
a Makefile allowing their compilation entering the command "make".
You possibly need to edit the Makefile to correct the name of the
compiler and set your favourite compilation options.

In fact, these Makefile just make sure that the application program
is compiled together with SRC/dagmg.f90 and SRC/dagmg_mumps.f90 in the
sequential case, and with SRC/dagmg_par.f90  in the parallel case.
You may proceed in a similar way with any application program.
(Hence, AGMG need not be installed as a library).

Note, however, that the Makefile also avoids recompiling dagmg.f90
dagmg_mumps.f90 or dagmg_par.f90 when only the application program
has been changed. This is strongly recommended. In particular,
the compilation of dagmg_mumps.f90 is time consuming.

Please note also that, with the most recent versions of gfortran
(4.6.0 and above), dagmg_mumps.f90 cannot be compiled with highest
optimization: it is needed to use the options: "-O2 -fno-whole-file".
This is harmless because normally only a small amount of time
is spent in this part of the code; most time is spent in
subroutines from the file dagmg.f90, which can be compiled
trouble free with highest optimization level.

The provided examples use the double precision version. To use the
single, complex or double complex version, proceed similarly
exchanging in the file the prefix "d" for, respectively, "s", "c" or "z".

AGMG requires LAPACK and BLAS libraries; in addition, the parallel
version requires the MUMPS library. These software are public domain and
easily found on the Web, see the userguide for references. In addition,
LAPACK and BLAS come pre-installed with most compilers.
If you don't have LAPACK pre-installed, you may compile, instead of downloading
the full library, the file SRC/lapack_agmg.f together with other program
files. This will provide needed LAPACK routines. Similarly, if you don't
have BLAS pre-installed, you may compile, instead of downloading
the full library, the file SRC/blas_agmg.f together with other program
files. This will provide needed BLAS routines.
We however strongly recommend to use pre-installed libraries whenever available.

Note that the provided Makefile needs possibly to be edited to correct the
variable BLASLAPACK which contains the option for linking with LAPACK & BLAS.
The Makefile of the parallel example also refers to several variables,
which should be edited according your local installation.


Matlab
------

Files for the Matlab interface are located in directory /MYDIR/AGMG_3.1.2/Matlab/

The user interface is in the file agmg.m (matlab function)
Enter "help agmg" in the matlab environment for basic usage.
A more detailed description of optional parameters and of
verbose output is provided in the userguide in /MYDIR/AGMG_3.1.2/Doc/
(see in particular Sections 2.2 and 2.4, and also Sections 4 and 5
for some special usages)

Besides, we also provide in the file agtwolev.m a matlab function
that only performs aggregation according to the algorithm in
either [2] or [3]. This is not intended to help solving linear systems,
but rather to facilitate further research and developments.
Enter "help agtwolev" in the matlab environment for more details
on function usage, which allows to easily play with the parameters
referenced in [2,3].

For most users, the precompiled files dmtlagmg.mex??? and zmtlagmg.mex???
(where ??? depends upon your OS and architecture) are all what is
needed to run properly the function in agmg.m ; i.e., you need only to place
the three files (agmg.m , dmtlagmg.mex??? and zmtlagmg.mex??? )
in a directory in which Matlab can find scripts & executables.

Similarly, dmtlagtwolev.mex??? contains all what is needed to run agtwolev.m.

If no precompiled file exists for your architecture, you can generate them
with the commands

mex -O -largeArrayDims dmtlagmg.c dagmg_mex.f90 dagmg_mumps_mex.f90 -lmwlapack -lmwblas
mex -O -largeArrayDims zmtlagmg.c zagmg_mex.f90 zagmg_mumps_mex.f90 -lmwlapack -lmwblas
mex -O -largeArrayDims dmtlagtwolev.c dagtwolev_mex.f90 -lmwlapack -lmwblas

This compilation can occasionally raise some difficulties (it requires
proper C and FORTRAN compilers to be installed). If you generate in this
way dmtlagmg.mex??? , zmtlagmg.mex??? and dmtlagtwolev.mex??? files that
are so far missing in the package, it is a good idea to forward them to us
(mailto:[email protected]).
They will then be made available to everybody.


Release notes
-------------
See the userguide in /MYDIR/AGMG_3.1.2/Doc/ (in particular Section 1.2)
for a description of changes from previous releases 1.x and 2.x

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