1 #include <petsc/private/matimpl.h> 2 #include <petscsf.h> 3 4 /* this function maps rows to locally owned rows */ 5 PETSC_INTERN PetscErrorCode MatZeroRowsMapLocal_Private(Mat A,PetscInt N,const PetscInt *rows,PetscInt *nr,PetscInt **olrows) 6 { 7 PetscInt *owners = A->rmap->range; 8 PetscInt n = A->rmap->n; 9 PetscSF sf; 10 PetscInt *lrows; 11 PetscSFNode *rrows; 12 PetscMPIInt rank, p = 0; 13 PetscInt r, len = 0; 14 15 PetscFunctionBegin; 16 /* Create SF where leaves are input rows and roots are owned rows */ 17 PetscCallMPI(MPI_Comm_rank(PetscObjectComm((PetscObject)A),&rank)); 18 PetscCall(PetscMalloc1(n, &lrows)); 19 for (r = 0; r < n; ++r) lrows[r] = -1; 20 if (!A->nooffproczerorows) PetscCall(PetscMalloc1(N, &rrows)); 21 for (r = 0; r < N; ++r) { 22 const PetscInt idx = rows[r]; 23 PetscCheckFalse(idx < 0 || A->rmap->N <= idx,PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"Row %" PetscInt_FMT " out of range [0,%" PetscInt_FMT ")",idx,A->rmap->N); 24 if (idx < owners[p] || owners[p+1] <= idx) { /* short-circuit the search if the last p owns this row too */ 25 PetscCall(PetscLayoutFindOwner(A->rmap,idx,&p)); 26 } 27 if (A->nooffproczerorows) { 28 PetscCheck(p == rank,PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"MAT_NO_OFF_PROC_ZERO_ROWS set, but row %" PetscInt_FMT " is not owned by rank %d",idx,rank); 29 lrows[len++] = idx - owners[p]; 30 } else { 31 rrows[r].rank = p; 32 rrows[r].index = rows[r] - owners[p]; 33 } 34 } 35 if (!A->nooffproczerorows) { 36 PetscCall(PetscSFCreate(PetscObjectComm((PetscObject) A), &sf)); 37 PetscCall(PetscSFSetGraph(sf, n, N, NULL, PETSC_OWN_POINTER, rrows, PETSC_OWN_POINTER)); 38 /* Collect flags for rows to be zeroed */ 39 PetscCall(PetscSFReduceBegin(sf, MPIU_INT, (PetscInt*)rows, lrows, MPI_LOR)); 40 PetscCall(PetscSFReduceEnd(sf, MPIU_INT, (PetscInt*)rows, lrows, MPI_LOR)); 41 PetscCall(PetscSFDestroy(&sf)); 42 /* Compress and put in row numbers */ 43 for (r = 0; r < n; ++r) if (lrows[r] >= 0) lrows[len++] = r; 44 } 45 if (nr) *nr = len; 46 if (olrows) *olrows = lrows; 47 PetscFunctionReturn(0); 48 } 49