blacs_gridinit/mpi_init, blacs_gridexit/mpi_finalize

[amolins]

what is the correct way of starting BLACS? do I have to call mpi_init beforehand, or does it suffice with calling blacs_gridinit? what about closing blacs?

Thanks

[Julie]

You will find useful examples of how to use BLACS here.
http://www.netlib.org/blacs/BLACS/Examples.html

Julie

[amolins]

what about in C? and what about the proper way of doing it with MPI_Init / MPI_Finalize? the link does not answer any of these questions.

[gajjar]

Have a look at http://geco.mines.edu/software/mkl/linsolve.f90

The answer is
call MPI_INIT(code)

call MPI_COMM_SIZE(MPI_COMM_WORLD,nb_procs,code)
call MPI_COMM_RANK(MPI_COMM_WORLD,rank,code)
call MPI_Errhandler_set(MPI_COMM_WORLD, MPI_ERRORS_RETURN,code);
!**************************************
...
call blacs_get(icontxt,0,value)
call blacs_gridinit(icontxt,'R',nprow,npcol)
call blacs_gridinfo(icontxt,nprow,npcol,myrow,mycol)

call mpi_finalize(code)