=========================
INSTALLING anuga_parallel
=========================

MPI
===

First thing, you need to install MPI on your system. OPENMPI and MPICH2 
are supported by pypar (see below) so both should be ok. 

Make sure mpi works. You should be able to run a program in parallel. 

Try something as simple as 

mpirun -np 4 pwd

should produce the output of pwd 4 times. 

PYPAR
======

We use pypar as the interface between mpi and python. The most recent 
version of PYPAR is available from 

http://code.google.com/p/pypar/ 

(There is an old version on sourceforge
http://sourceforge.net/projects/pypar/)

Install pypar following the instructions in hte download. Should be able
use standard python setup.py install

Make sure the pypar examples work


PYMETIS
=======

In the anuga_parallel directory there is a subdirectory pymetis. 

Follow the instructions in README to install. Essentially just run make.

From the pymetis directory, test using test_all.py

ANUGA_PARALLEL
==============

Should now be ready to run some parallel anuga code.

Go back to the anuga_parallel directory and run test_all.py

Hopefully that all works.

Run run_parallel_sw_merimbula.py

First just run it a sequential program. 

Then try a parallel run using a command like

mpirun -np 4 python run_parallel_sw_merimbula.py

That should run on 4 processors

You should look at the code in  run_parallel_sw_merimbula.py

Essentially a fairly standard example, with the extra command 

domain = distribute(domain)

which sets up all the parallel stuff.

Also for efficiency reasons we only setup the original full sequential mesh 
on processor 0, hence the statement

if myid == 0:
     domain = create_domain_from_file(mesh_filename)
     domain.set_quantity('stage', Set_Stage(x0, x1, 2.0))
else:
     domain = None

The output will be an sww file associated to each 
processor. 

There is a script anuga/utilities/sww_merge.py which provides
a function to merge sww files into one sww file for viewing 
with the anuga viewer.