Date: 2026-03-01T05:24:53+00:00

Actual source code: util.c

      1: /*
      2:  GAMG geometric-algebric multigrid PC - Mark Adams 2011
      3:  */
      4: #include <petsc/private/matimpl.h>
      5: #include <../src/ksp/pc/impls/gamg/gamg.h>
      6: #include <petsc/private/kspimpl.h>

      8: // PetscClangLinter pragma disable: -fdoc-sowing-chars
      9: /*
     10:   PCGAMGGetDataWithGhosts - Get array of local + ghost data with local data
     11:   hacks into Mat MPIAIJ so this must have size > 1

     13:   Input Parameters:
     14: + Gmat    - MPIAIJ matrix for scatters
     15: . data_sz - number of data terms per node (# cols in output)
     16: - data_in - column-oriented local data of size nloc*data_sz

     18:   Output Parameters:
     19: + a_stride - number of rows of output (locals+ghosts)
     20: - a_data_out - output data with ghosts of size stride*data_sz

     22: */
     23: PetscErrorCode PCGAMGGetDataWithGhosts(Mat Gmat, PetscInt data_sz, PetscReal data_in[], PetscInt *a_stride, PetscReal **a_data_out)
     24: {
     25:   Vec          tmp_crds;
     26:   Mat_MPIAIJ  *mpimat;
     27:   PetscInt     nnodes, num_ghosts, dir, kk, jj, my0, Iend, nloc;
     28:   PetscScalar *data_arr;
     29:   PetscReal   *datas;
     30:   PetscBool    isMPIAIJ;

     32:   PetscFunctionBegin;
     34:   mpimat = (Mat_MPIAIJ *)Gmat->data;
     35:   PetscCall(PetscObjectBaseTypeCompare((PetscObject)Gmat, MATMPIAIJ, &isMPIAIJ));
     36:   PetscCall(MatGetOwnershipRange(Gmat, &my0, &Iend));
     37:   nloc = Iend - my0;
     38:   PetscCall(VecGetLocalSize(mpimat->lvec, &num_ghosts));
     39:   nnodes    = num_ghosts + nloc;
     40:   *a_stride = nnodes;
     41:   PetscCall(MatCreateVecs(Gmat, &tmp_crds, NULL));

     43:   PetscCall(PetscMalloc1(data_sz * nnodes, &datas));
     44:   for (dir = 0; dir < data_sz; dir++) {
     45:     /* set local, and global */
     46:     for (kk = 0; kk < nloc; kk++) {
     47:       PetscInt    gid          = my0 + kk;
     48:       PetscScalar crd          = data_in[dir * nloc + kk]; /* col oriented */
     49:       datas[dir * nnodes + kk] = PetscRealPart(crd);       // get local part now

     51:       PetscCall(VecSetValues(tmp_crds, 1, &gid, &crd, INSERT_VALUES));
     52:     }
     53:     PetscCall(VecAssemblyBegin(tmp_crds));
     54:     PetscCall(VecAssemblyEnd(tmp_crds));
     55:     /* scatter / gather ghost data and add to end of output data */
     56:     PetscCall(VecScatterBegin(mpimat->Mvctx, tmp_crds, mpimat->lvec, INSERT_VALUES, SCATTER_FORWARD));
     57:     PetscCall(VecScatterEnd(mpimat->Mvctx, tmp_crds, mpimat->lvec, INSERT_VALUES, SCATTER_FORWARD));
     58:     PetscCall(VecGetArray(mpimat->lvec, &data_arr));
     59:     for (kk = nloc, jj = 0; jj < num_ghosts; kk++, jj++) datas[dir * nnodes + kk] = PetscRealPart(data_arr[jj]);
     60:     PetscCall(VecRestoreArray(mpimat->lvec, &data_arr));
     61:   }
     62:   PetscCall(VecDestroy(&tmp_crds));
     63:   *a_data_out = datas;
     64:   PetscFunctionReturn(PETSC_SUCCESS);
     65: }