PetscErrorCode PCGAMGCoarsen_Classical(PC pc,Mat *G,PetscCoarsenData **agg_lists)
{
PetscErrorCode ierr;
MatCoarsen crs;
MPI_Comm fcomm = ((PetscObject)pc)->comm;
PetscFunctionBegin;
/* construct the graph if necessary */
if (!G) {
SETERRQ(fcomm,PETSC_ERR_ARG_WRONGSTATE,"Must set Graph in PC in PCGAMG before coarsening");
}
ierr = MatCoarsenCreate(fcomm,&crs);CHKERRQ(ierr);
ierr = MatCoarsenSetFromOptions(crs);CHKERRQ(ierr);
ierr = MatCoarsenSetAdjacency(crs,*G);CHKERRQ(ierr);
ierr = MatCoarsenSetStrictAggs(crs,PETSC_TRUE);CHKERRQ(ierr);
ierr = MatCoarsenApply(crs);CHKERRQ(ierr);
ierr = MatCoarsenGetData(crs,agg_lists);CHKERRQ(ierr);
ierr = MatCoarsenDestroy(&crs);CHKERRQ(ierr);
PetscFunctionReturn(0);
}
PetscErrorCode PCGAMGcoarsen_GEO(PC a_pc,Mat *a_Gmat,PetscCoarsenData **a_llist_parent)
{
PetscErrorCode ierr;
PC_MG *mg = (PC_MG*)a_pc->data;
PC_GAMG *pc_gamg = (PC_GAMG*)mg->innerctx;
PetscInt Istart,Iend,nloc,kk,Ii,ncols;
PetscMPIInt rank,size;
IS perm;
GAMGNode *gnodes;
PetscInt *permute;
Mat Gmat = *a_Gmat;
MPI_Comm comm;
MatCoarsen crs;
PetscFunctionBegin;
ierr = PetscObjectGetComm((PetscObject)a_pc,&comm);CHKERRQ(ierr);
#if defined PETSC_USE_LOG
ierr = PetscLogEventBegin(PC_GAMGCoarsen_GEO,0,0,0,0);CHKERRQ(ierr);
#endif
ierr = MPI_Comm_rank(comm, &rank);CHKERRQ(ierr);
ierr = MPI_Comm_size(comm, &size);CHKERRQ(ierr);
ierr = MatGetOwnershipRange(Gmat, &Istart, &Iend);CHKERRQ(ierr);
nloc = (Iend-Istart);
/* create random permutation with sort for geo-mg */
ierr = PetscMalloc1(nloc, &gnodes);CHKERRQ(ierr);
ierr = PetscMalloc1(nloc, &permute);CHKERRQ(ierr);
for (Ii=Istart; Ii<Iend; Ii++) { /* locals only? */
ierr = MatGetRow(Gmat,Ii,&ncols,0,0);CHKERRQ(ierr);
{
PetscInt lid = Ii - Istart;
gnodes[lid].lid = lid;
gnodes[lid].degree = ncols;
}
ierr = MatRestoreRow(Gmat,Ii,&ncols,0,0);CHKERRQ(ierr);
}
/* randomize */
srand(1); /* make deterministic */
if (PETSC_TRUE) {
PetscBool *bIndexSet;
ierr = PetscMalloc1(nloc, &bIndexSet);CHKERRQ(ierr);
for (Ii = 0; Ii < nloc; Ii++) bIndexSet[Ii] = PETSC_FALSE;
for (Ii = 0; Ii < nloc; Ii++) {
PetscInt iSwapIndex = rand()%nloc;
if (!bIndexSet[iSwapIndex] && iSwapIndex != Ii) {
GAMGNode iTemp = gnodes[iSwapIndex];
gnodes[iSwapIndex] = gnodes[Ii];
gnodes[Ii] = iTemp;
bIndexSet[Ii] = PETSC_TRUE;
bIndexSet[iSwapIndex] = PETSC_TRUE;
}
}
ierr = PetscFree(bIndexSet);CHKERRQ(ierr);
}
/* only sort locals */
qsort(gnodes, nloc, sizeof(GAMGNode), petsc_geo_mg_compare);
/* create IS of permutation */
for (kk=0; kk<nloc; kk++) permute[kk] = gnodes[kk].lid; /* locals only */
ierr = ISCreateGeneral(PETSC_COMM_SELF, nloc, permute, PETSC_OWN_POINTER, &perm);CHKERRQ(ierr);
ierr = PetscFree(gnodes);CHKERRQ(ierr);
/* get MIS aggs */
ierr = MatCoarsenCreate(comm, &crs);CHKERRQ(ierr);
ierr = MatCoarsenSetType(crs, MATCOARSENMIS);CHKERRQ(ierr);
ierr = MatCoarsenSetGreedyOrdering(crs, perm);CHKERRQ(ierr);
ierr = MatCoarsenSetAdjacency(crs, Gmat);CHKERRQ(ierr);
ierr = MatCoarsenSetVerbose(crs, pc_gamg->verbose);CHKERRQ(ierr);
ierr = MatCoarsenSetStrictAggs(crs, PETSC_FALSE);CHKERRQ(ierr);
ierr = MatCoarsenApply(crs);CHKERRQ(ierr);
ierr = MatCoarsenGetData(crs, a_llist_parent);CHKERRQ(ierr);
ierr = MatCoarsenDestroy(&crs);CHKERRQ(ierr);
ierr = ISDestroy(&perm);CHKERRQ(ierr);
#if defined PETSC_USE_LOG
ierr = PetscLogEventEnd(PC_GAMGCoarsen_GEO,0,0,0,0);CHKERRQ(ierr);
#endif
PetscFunctionReturn(0);
}