Mark, thanks for the quick response. I am more interested in parallel implementation of MatMult for SBAIJ. I found following
1094: *PetscErrorCode <https://petsc.org/main/docs/manualpages/Sys/PetscErrorCode.html#PetscErrorCode> MatMult_MPISBAIJ(Mat <https://petsc.org/main/docs/manualpages/Mat/Mat.html#Mat> A,Vec <https://petsc.org/main/docs/manualpages/Vec/Vec.html#Vec> xx,Vec <https://petsc.org/main/docs/manualpages/Vec/Vec.html#Vec> yy)*1095: {1096: Mat_MPISBAIJ *a = (Mat_MPISBAIJ*)A->data;1097: PetscErrorCode <https://petsc.org/main/docs/manualpages/Sys/PetscErrorCode.html#PetscErrorCode> ierr;1098: PetscInt <https://petsc.org/main/docs/manualpages/Sys/PetscInt.html#PetscInt> mbs=a->mbs,bs=A->rmap->bs;1099: PetscScalar <https://petsc.org/main/docs/manualpages/Sys/PetscScalar.html#PetscScalar> *from;1100: const PetscScalar <https://petsc.org/main/docs/manualpages/Sys/PetscScalar.html#PetscScalar> *x; 1103: /* diagonal part */1104: (*a->A->ops->mult)(a->A,xx,a->slvec1a);1105: VecSet <https://petsc.org/main/docs/manualpages/Vec/VecSet.html#VecSet>(a->slvec1b,0.0); 1107: /* subdiagonal part */1108: (*a->B->ops->multtranspose)(a->B,xx,a->slvec0b); 1110: /* copy x into the vec slvec0 */1111: VecGetArray <https://petsc.org/main/docs/manualpages/Vec/VecGetArray.html#VecGetArray>(a->slvec0,&from);1112: VecGetArrayRead <https://petsc.org/main/docs/manualpages/Vec/VecGetArrayRead.html#VecGetArrayRead>(xx,&x); 1114: PetscArraycpy <https://petsc.org/main/docs/manualpages/Sys/PetscArraycpy.html#PetscArraycpy>(from,x,bs*mbs);1115: VecRestoreArray <https://petsc.org/main/docs/manualpages/Vec/VecRestoreArray.html#VecRestoreArray>(a->slvec0,&from);1116: VecRestoreArrayRead <https://petsc.org/main/docs/manualpages/Vec/VecRestoreArrayRead.html#VecRestoreArrayRead>(xx,&x); 1118: VecScatterBegin <https://petsc.org/main/docs/manualpages/PetscSF/VecScatterBegin.html#VecScatterBegin>(a->sMvctx,a->slvec0,a->slvec1,ADD_VALUES <https://petsc.org/main/docs/manualpages/Sys/ADD_VALUES.html#ADD_VALUES>,SCATTER_FORWARD <https://petsc.org/main/docs/manualpages/Vec/SCATTER_FORWARD.html#SCATTER_FORWARD>);1119: VecScatterEnd <https://petsc.org/main/docs/manualpages/PetscSF/VecScatterEnd.html#VecScatterEnd>(a->sMvctx,a->slvec0,a->slvec1,ADD_VALUES <https://petsc.org/main/docs/manualpages/Sys/ADD_VALUES.html#ADD_VALUES>,SCATTER_FORWARD <https://petsc.org/main/docs/manualpages/Vec/SCATTER_FORWARD.html#SCATTER_FORWARD>);1120: /* supperdiagonal part */1121: (*a->B->ops->multadd)(a->B,a->slvec1b,a->slvec1a,yy);1122: return(0);1123: } I try to understand the algorithm. Thanks, Sam On Mon, Mar 21, 2022 at 11:14 AM Mark Adams <[email protected]> wrote: > This code looks fine to me and the code is > in src/mat/impls/sbaij/seq/sbaij2.c > > On Mon, Mar 21, 2022 at 2:02 PM Sam Guo <[email protected]> wrote: > >> Dear PETSc dev team, >> The documentation about MatCreateSBAIJ has following >> "It is recommended that one use the MatCreate >> <https://petsc.org/main/docs/manualpages/Mat/MatCreate.html#MatCreate> >> (), MatSetType >> <https://petsc.org/main/docs/manualpages/Mat/MatSetType.html#MatSetType>() >> and/or MatSetFromOptions >> <https://petsc.org/main/docs/manualpages/Mat/MatSetFromOptions.html#MatSetFromOptions>(), >> MatXXXXSetPreallocation() paradigm instead of this routine directly. >> [MatXXXXSetPreallocation() is, for example, MatSeqAIJSetPreallocation >> <https://petsc.org/main/docs/manualpages/Mat/MatSeqAIJSetPreallocation.html#MatSeqAIJSetPreallocation> >> ]" >> I currently call MatCreateSBAIJ directly as follows: >> MatCreateSBAIJ (with d_nnz and o_nnz) >> MatSetValues (to add row by row) >> MatAssemblyBegin(A,MAT_FINAL_ASSEMBLY); >> MatAssemblyEnd(A,MAT_FINAL_ASSEMBLY); >> MatSetOption(A, MAT_SYMMETRIC, PETSC_TRUE); >> >> Two questions: >> (1) I am wondering whether what I am doing is the most efficient. >> >> (2) I try to find out how the matrix vector multiplication is >> implemented in PETSc for SBAIJ storage. >> >> Thanks, >> Sam >> >
