PETSC_EXTERN void PETSC_STDCALL pcissetsubdomainscalingfactor_(PC pc,PetscScalar *scal, int *__ierr ){
*__ierr = PCISSetSubdomainScalingFactor(
(PC)PetscToPointer((pc) ),*scal);
}
static PetscErrorCode ComputeKSPBDDC(DomainData dd,Mat A,KSP *ksp)
{
PetscErrorCode ierr;
KSP temp_ksp;
PC pc;
IS dirichletIS=0,neumannIS=0,*bddc_dofs_splitting;
PetscInt localsize,*xadj=NULL,*adjncy=NULL;
MatNullSpace near_null_space;
PetscFunctionBeginUser;
ierr = KSPCreate(dd.gcomm,&temp_ksp);CHKERRQ(ierr);
ierr = KSPSetOperators(temp_ksp,A,A);CHKERRQ(ierr);
ierr = KSPSetType(temp_ksp,KSPCG);CHKERRQ(ierr);
ierr = KSPGetPC(temp_ksp,&pc);CHKERRQ(ierr);
ierr = PCSetType(pc,PCBDDC);CHKERRQ(ierr);
localsize = dd.xm_l*dd.ym_l*dd.zm_l;
/* BDDC customization */
/* jumping coefficients case */
ierr = PCISSetSubdomainScalingFactor(pc,dd.scalingfactor);CHKERRQ(ierr);
/* Dofs splitting
Simple stride-1 IS
It is not needed since, by default, PCBDDC assumes a stride-1 split */
ierr = PetscMalloc1(1,&bddc_dofs_splitting);CHKERRQ(ierr);
#if 1
ierr = ISCreateStride(PETSC_COMM_WORLD,localsize,0,1,&bddc_dofs_splitting[0]);CHKERRQ(ierr);
ierr = PCBDDCSetDofsSplittingLocal(pc,1,bddc_dofs_splitting);CHKERRQ(ierr);
#else
/* examples for global ordering */
/* each process lists the nodes it owns */
PetscInt sr,er;
ierr = MatGetOwnershipRange(A,&sr,&er);CHKERRQ(ierr);
ierr = ISCreateStride(PETSC_COMM_WORLD,er-sr,sr,1,&bddc_dofs_splitting[0]);CHKERRQ(ierr);
ierr = PCBDDCSetDofsSplitting(pc,1,bddc_dofs_splitting);CHKERRQ(ierr);
/* Split can be passed in a more general way since any process can list any node */
#endif
ierr = ISDestroy(&bddc_dofs_splitting[0]);CHKERRQ(ierr);
ierr = PetscFree(bddc_dofs_splitting);CHKERRQ(ierr);
/* Primal constraints implemented by using a near null space attached to A -> now it passes in only the constants
(which in practice is not needed since, by default, PCBDDC build the primal space using constants for quadrature formulas */
#if 0
Vec vecs[2];
PetscRandom rctx;
ierr = MatCreateVecs(A,&vecs[0],&vecs[1]);CHKERRQ(ierr);
ierr = PetscRandomCreate(dd.gcomm,&rctx);CHKERRQ(ierr);
ierr = VecSetRandom(vecs[0],rctx);CHKERRQ(ierr);
ierr = VecSetRandom(vecs[1],rctx);CHKERRQ(ierr);
ierr = MatNullSpaceCreate(dd.gcomm,PETSC_TRUE,2,vecs,&near_null_space);CHKERRQ(ierr);
ierr = VecDestroy(&vecs[0]);CHKERRQ(ierr);
ierr = VecDestroy(&vecs[1]);CHKERRQ(ierr);
ierr = PetscRandomDestroy(&rctx);CHKERRQ(ierr);
#else
ierr = MatNullSpaceCreate(dd.gcomm,PETSC_TRUE,0,NULL,&near_null_space);CHKERRQ(ierr);
#endif
ierr = MatSetNearNullSpace(A,near_null_space);CHKERRQ(ierr);
ierr = MatNullSpaceDestroy(&near_null_space);CHKERRQ(ierr);
/* CSR graph of subdomain dofs */
ierr = BuildCSRGraph(dd,&xadj,&adjncy);CHKERRQ(ierr);
ierr = PCBDDCSetLocalAdjacencyGraph(pc,localsize,xadj,adjncy,PETSC_OWN_POINTER);CHKERRQ(ierr);
/* Neumann/Dirichlet indices on the global boundary */
if (dd.DBC_zerorows) {
/* Only in case you eliminate some rows matrix with zerorows function, you need to set dirichlet indices into PCBDDC data */
ierr = ComputeSpecialBoundaryIndices(dd,&dirichletIS,&neumannIS);CHKERRQ(ierr);
ierr = PCBDDCSetNeumannBoundariesLocal(pc,neumannIS);CHKERRQ(ierr);
ierr = PCBDDCSetDirichletBoundariesLocal(pc,dirichletIS);CHKERRQ(ierr);
} else {
if (dd.pure_neumann) {
/* In such a case, all interface nodes lying on the global boundary are neumann nodes */
ierr = ComputeSpecialBoundaryIndices(dd,NULL,&neumannIS);CHKERRQ(ierr);
ierr = PCBDDCSetNeumannBoundariesLocal(pc,neumannIS);CHKERRQ(ierr);
} else {
/* It is wrong setting dirichlet indices without having zeroed the corresponding rows in the global matrix */
/* But we can still compute them since nodes near the dirichlet boundaries does not need to be defined as neumann nodes */
ierr = ComputeSpecialBoundaryIndices(dd,&dirichletIS,&neumannIS);CHKERRQ(ierr);
ierr = PCBDDCSetNeumannBoundariesLocal(pc,neumannIS);CHKERRQ(ierr);
}
}
/* Pass local null space information to local matrices (needed when using approximate local solvers) */
if (dd.ipx || dd.pure_neumann) {
MatNullSpace nsp;
Mat local_mat;
ierr = MatISGetLocalMat(A,&local_mat);CHKERRQ(ierr);
ierr = MatNullSpaceCreate(PETSC_COMM_SELF,PETSC_TRUE,0,NULL,&nsp);CHKERRQ(ierr);
ierr = MatSetNullSpace(local_mat,nsp);CHKERRQ(ierr);
ierr = MatNullSpaceDestroy(&nsp);CHKERRQ(ierr);
}
ierr = KSPSetComputeSingularValues(temp_ksp,PETSC_TRUE);CHKERRQ(ierr);
ierr = KSPSetFromOptions(temp_ksp);CHKERRQ(ierr);
ierr = KSPSetUp(temp_ksp);CHKERRQ(ierr);
*ksp = temp_ksp;
ierr = ISDestroy(&dirichletIS);CHKERRQ(ierr);
ierr = ISDestroy(&neumannIS);CHKERRQ(ierr);
PetscFunctionReturn(0);
}