Hi there,
I am trying to build a parallel PETSc sparse matrix by building a local
sparsity pattern and subsequently distributing the pattern to all processes so
I then have the full sparsity pattern for the PETSc sparse matrix (I read this
needs to be done but please correct me if I am wrong). When I try to reinit the
PETSc sparse matrix I get a segfault so I am hunting down the problem.
My understanding for “distribute_sparsity_pattern” is it sends local sparsity
patterns to all other processes and saves the full global pattern in the
dynamic sparsity pattern you passed in. So I figured that after I call this
function, my local number of rows should be the global number of rows but the
number of rows is the same as before I called this function (i.e. the actual
local number of rows) so I think I am not using this function correctly and my
PETSc sparse matrix doesn’t have the global dynamic sparsity pattern I think it
must have, which results in a segfault.
NOTE: The matrix is a square matrix with rows and columns of size “nbas *
nchannels” and the rows are divided amongst the processes.
Here is the code for distributing my locally built sparsity pattern dsp:
IndexSet local_owned( nbas * nchannels * nbas * nchannels ); \\ allocate global
sized index set
local_owned.add_range( LocalStart(), LocalEnd() ); \\ start of local row first
column and end of last local row at last column
SparsityTools::distribute_sparsity_pattern( dsp, local_owned, comm, local_owned
);
Here is the code for initializing my PETSc sparse matrix:
std::vector<size_type> local_rows_per_process( num_procs); // allocate a vector
of length number of process
std::vector<size_type> local_columns_per_process( num_procs, nbas * nchannels);
// columns are full length and rows are divided by num_procs
for(int i=0; i < num_procs; ++i )
{
local_rows_per_process[ i ] = i * local_rows; // Saw this in a test but
initially thought this should just all be local_rows for each i
}
Matrix.reinit( comm, dsp, local_rows_per_process, local_columns_per_process,
my_proc);
--
The deal.II project is located at http://www.dealii.org/
For mailing list/forum options, see
https://groups.google.com/d/forum/dealii?hl=en
---
You received this message because you are subscribed to the Google Groups
"deal.II User Group" group.
To unsubscribe from this group and stop receiving emails from it, send an email
to [email protected].
To view this discussion on the web visit
https://groups.google.com/d/msgid/dealii/1942C0DC-2A53-4A9C-AFD6-C136192C72DB%40gmail.com.
