petsc_parallel_sparse_matrix.cc

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// -----------------------------------------------------------------------------
//
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception OR LGPL-2.1-or-later
// Copyright (C) 2004 - 2026 by the deal.II authors
//
// This file is part of the deal.II library.
//
// Detailed license information governing the source code and contributions
// can be found in LICENSE.md and CONTRIBUTING.md at the top level directory.
//
// -----------------------------------------------------------------------------
 
#include <deal.II/lac/petsc_sparse_matrix.h>
 
#ifdef DEAL_II_WITH_PETSC
 
#  include <deal.II/base/mpi.h>
 
#  include <deal.II/lac/dynamic_sparsity_pattern.h>
#  include <deal.II/lac/exceptions.h>
#  include <deal.II/lac/petsc_compatibility.h>
#  include <deal.II/lac/petsc_vector.h>
#  include <deal.II/lac/sparsity_pattern.h>
 
 
#endif // DEAL_II_WITH_PETSC
 
DEAL_II_NAMESPACE_OPEN
 
#ifdef DEAL_II_WITH_PETSC
 
namespace PETScWrappers
{
  namespace MPI
  {
    SparseMatrix::SparseMatrix()
    {
      // just like for vectors: since we
      // create an empty matrix, we can as
      // well make it sequential
      const int            m = 0, n = 0, n_nonzero_per_row = 0;
      const PetscErrorCode ierr = MatCreateSeqAIJ(
        PETSC_COMM_SELF, m, n, n_nonzero_per_row, nullptr, &matrix);
      AssertThrow(ierr == 0, ExcPETScError(ierr));
    }
 
    SparseMatrix::SparseMatrix(const Mat &A)
      : MatrixBase(A)
    {}
 
    SparseMatrix::~SparseMatrix()
    {
      PetscErrorCode ierr = MatDestroy(&matrix);
      AssertNothrow(ierr == 0, ExcPETScError(ierr));
    }
 
 
 
    template <typename SparsityPatternType>
    SparseMatrix::SparseMatrix(
      const MPI_Comm                communicator,
      const SparsityPatternType    &sparsity_pattern,
      const std::vector<size_type> &local_rows_per_process,
      const std::vector<size_type> &local_columns_per_process,
      const unsigned int            this_process,
      const bool                    preset_nonzero_locations)
    {
      do_reinit(communicator,
                sparsity_pattern,
                local_rows_per_process,
                local_columns_per_process,
                this_process,
                preset_nonzero_locations);
    }
 
 
 
    void
    SparseMatrix::reinit(const SparseMatrix &other)
    {
      if (&other == this)
        return;
 
      PetscErrorCode ierr = MatDestroy(&matrix);
      AssertThrow(ierr == 0, ExcPETScError(ierr));
 
      ierr = MatDuplicate(other.matrix, MAT_DO_NOT_COPY_VALUES, &matrix);
      AssertThrow(ierr == 0, ExcPETScError(ierr));
    }
 
    template <typename SparsityPatternType>
    void
    SparseMatrix::reinit(const IndexSet            &local_rows,
                         const IndexSet            &local_active_rows,
                         const IndexSet            &local_columns,
                         const IndexSet            &local_active_columns,
                         const SparsityPatternType &sparsity_pattern,
                         const MPI_Comm             communicator)
    {
      // get rid of old matrix and generate a new one
      const PetscErrorCode ierr = MatDestroy(&matrix);
      AssertThrow(ierr == 0, ExcPETScError(ierr));
 
      do_reinit(communicator,
                local_rows,
                local_active_rows,
                local_columns,
                local_active_columns,
                sparsity_pattern);
    }
 
 
    SparseMatrix &
    SparseMatrix::operator=(const value_type d)
    {
      MatrixBase::operator=(d);
      return *this;
    }
 
    void
    SparseMatrix::copy_from(const SparseMatrix &other)
    {
      if (&other == this)
        return;
 
      const PetscErrorCode ierr =
        MatCopy(other.matrix, matrix, SAME_NONZERO_PATTERN);
      AssertThrow(ierr == 0, ExcPETScError(ierr));
    }
 
 
 
    template <typename SparsityPatternType>
    void
    SparseMatrix::reinit(
      const MPI_Comm                communicator,
      const SparsityPatternType    &sparsity_pattern,
      const std::vector<size_type> &local_rows_per_process,
      const std::vector<size_type> &local_columns_per_process,
      const unsigned int            this_process,
      const bool                    preset_nonzero_locations)
    {
      // get rid of old matrix and generate a new one
      const PetscErrorCode ierr = MatDestroy(&matrix);
      AssertThrow(ierr == 0, ExcPETScError(ierr));
 
 
      do_reinit(communicator,
                sparsity_pattern,
                local_rows_per_process,
                local_columns_per_process,
                this_process,
                preset_nonzero_locations);
    }
 
 
 
    template <typename SparsityPatternType>
    void
    SparseMatrix::reinit(const IndexSet            &local_rows,
                         const SparsityPatternType &sparsity_pattern,
                         const MPI_Comm             communicator)
    {
      do_reinit(communicator, local_rows, local_rows, sparsity_pattern);
    }
 
    template <typename SparsityPatternType>
    void
    SparseMatrix::reinit(const IndexSet            &local_rows,
                         const IndexSet            &local_columns,
                         const SparsityPatternType &sparsity_pattern,
                         const MPI_Comm             communicator)
    {
      // get rid of old matrix and generate a new one
      const PetscErrorCode ierr = MatDestroy(&matrix);
      AssertThrow(ierr == 0, ExcPETScError(ierr));
 
      do_reinit(communicator, local_rows, local_columns, sparsity_pattern);
    }
 
 
 
    template <typename SparsityPatternType>
    void
    SparseMatrix::do_reinit(const MPI_Comm             communicator,
                            const IndexSet            &local_rows,
                            const IndexSet            &local_columns,
                            const SparsityPatternType &sparsity_pattern)
    {
      // If the sparsity pattern's dimensions can be converted to PetscInts then
      // the rest of the conversions will succeed
      AssertThrowIntegerConversion(static_cast<PetscInt>(
                                     sparsity_pattern.n_rows()),
                                   sparsity_pattern.n_rows());
      AssertThrowIntegerConversion(static_cast<PetscInt>(
                                     sparsity_pattern.n_cols()),
                                   sparsity_pattern.n_cols());
 
      Assert(sparsity_pattern.n_rows() == local_rows.size(),
             ExcMessage(
               "SparsityPattern and IndexSet have different number of rows"));
      Assert(
        sparsity_pattern.n_cols() == local_columns.size(),
        ExcMessage(
          "SparsityPattern and IndexSet have different number of columns"));
      Assert(local_rows.is_contiguous() && local_columns.is_contiguous(),
             ExcMessage("PETSc only supports contiguous row/column ranges"));
      Assert(local_rows.is_ascending_and_one_to_one(communicator),
             ExcNotImplemented());
 
      if constexpr (running_in_debug_mode())
        {
          // check indexsets
          types::global_dof_index row_owners =
            Utilities::MPI::sum(local_rows.n_elements(), communicator);
          types::global_dof_index col_owners =
            Utilities::MPI::sum(local_columns.n_elements(), communicator);
          Assert(
            row_owners == sparsity_pattern.n_rows(),
            ExcMessage(
              std::string(
                "Each row has to be owned by exactly one owner (n_rows()=") +
              std::to_string(sparsity_pattern.n_rows()) +
              " but sum(local_rows.n_elements())=" +
              std::to_string(row_owners) + ")"));
          Assert(
            col_owners == sparsity_pattern.n_cols(),
            ExcMessage(
              std::string(
                "Each column has to be owned by exactly one owner (n_cols()=") +
              std::to_string(sparsity_pattern.n_cols()) +
              " but sum(local_columns.n_elements())=" +
              std::to_string(col_owners) + ")"));
        }
 
 
      // create the matrix. We do not set row length but set the
      // correct SparsityPattern later.
      PetscErrorCode ierr = MatCreate(communicator, &matrix);
      AssertThrow(ierr == 0, ExcPETScError(ierr));
 
      ierr = MatSetSizes(matrix,
                         local_rows.n_elements(),
                         local_columns.n_elements(),
                         sparsity_pattern.n_rows(),
                         sparsity_pattern.n_cols());
      AssertThrow(ierr == 0, ExcPETScError(ierr));
 
      // Use MATAIJ which dispatches to SEQAIJ
      // if the size of the communicator is 1,
      // and to MPIAIJ otherwise.
      ierr = MatSetType(matrix, MATAIJ);
      AssertThrow(ierr == 0, ExcPETScError(ierr));
 
 
      // next preset the exact given matrix
      // entries with zeros. this doesn't avoid any
      // memory allocations, but it at least
      // avoids some searches later on. the
      // key here is that we can use the
      // matrix set routines that set an
      // entire row at once, not a single
      // entry at a time
      //
      // for the usefulness of this option
      // read the documentation of this
      // class.
      // if (preset_nonzero_locations == true)
      if (local_rows.n_elements() > 0)
        {
          // MatXXXAIJSetPreallocationCSR
          // can be used to allocate the sparsity
          // pattern of a matrix
 
          const PetscInt local_row_start = local_rows.nth_index_in_set(0);
          const PetscInt local_row_end =
            local_row_start + local_rows.n_elements();
 
 
          // first set up the column number
          // array for the rows to be stored
          // on the local processor. have one
          // dummy entry at the end to make
          // sure petsc doesn't read past the
          // end
          std::vector<PetscInt> rowstart_in_window(local_row_end -
                                                     local_row_start + 1,
                                                   0),
            colnums_in_window;
          {
            unsigned int n_cols = 0;
            for (PetscInt i = local_row_start; i < local_row_end; ++i)
              {
                const PetscInt row_length = sparsity_pattern.row_length(i);
                rowstart_in_window[i + 1 - local_row_start] =
                  rowstart_in_window[i - local_row_start] + row_length;
                n_cols += row_length;
              }
            colnums_in_window.resize(n_cols + 1, -1);
          }
 
          // now copy over the information
          // from the sparsity pattern.
          {
            PetscInt *ptr = colnums_in_window.data();
            for (PetscInt i = local_row_start; i < local_row_end; ++i)
              for (typename SparsityPatternType::iterator p =
                     sparsity_pattern.begin(i);
                   p != sparsity_pattern.end(i);
                   ++p, ++ptr)
                *ptr = p->column();
          }
 
 
          // then call the petsc functions
          // that summarily allocates these
          // entries.
          // Here we both call the specific API since this is how
          // PETSc polymorphism works. If the matrix is of type MPIAIJ,
          // the second call is dummy. If the matrix is of type SEQAIJ,
          // the first call is dummy.
          ierr = MatMPIAIJSetPreallocationCSR(matrix,
                                              rowstart_in_window.data(),
                                              colnums_in_window.data(),
                                              nullptr);
          ierr = MatSeqAIJSetPreallocationCSR(matrix,
                                              rowstart_in_window.data(),
                                              colnums_in_window.data(),
                                              nullptr);
          AssertThrow(ierr == 0, ExcPETScError(ierr));
        }
      else
        {
          PetscInt i = 0;
 
          ierr = MatSeqAIJSetPreallocationCSR(matrix, &i, &i, nullptr);
          AssertThrow(ierr == 0, ExcPETScError(ierr));
          ierr = MatMPIAIJSetPreallocationCSR(matrix, &i, &i, nullptr);
          AssertThrow(ierr == 0, ExcPETScError(ierr));
        }
      compress(VectorOperation::insert);
 
      {
        close_matrix(matrix);
        set_keep_zero_rows(matrix);
      }
    }
 
 
    template <typename SparsityPatternType>
    void
    SparseMatrix::do_reinit(
      const MPI_Comm                communicator,
      const SparsityPatternType    &sparsity_pattern,
      const std::vector<size_type> &local_rows_per_process,
      const std::vector<size_type> &local_columns_per_process,
      const unsigned int            this_process,
      const bool                    preset_nonzero_locations)
    {
      Assert(local_rows_per_process.size() == local_columns_per_process.size(),
             ExcDimensionMismatch(local_rows_per_process.size(),
                                  local_columns_per_process.size()));
      Assert(this_process < local_rows_per_process.size(), ExcInternalError());
      assert_is_compressed();
      // If the sparsity pattern's dimensions can be converted to PetscInts then
      // the rest of the conversions will succeed
      AssertThrowIntegerConversion(static_cast<PetscInt>(
                                     sparsity_pattern.n_rows()),
                                   sparsity_pattern.n_rows());
      AssertThrowIntegerConversion(static_cast<PetscInt>(
                                     sparsity_pattern.n_cols()),
                                   sparsity_pattern.n_cols());
 
      // for each row that we own locally, we
      // have to count how many of the
      // entries in the sparsity pattern lie
      // in the column area we have locally,
      // and how many aren't. for this, we
      // first have to know which areas are
      // ours
      size_type local_row_start = 0;
      for (unsigned int p = 0; p < this_process; ++p)
        local_row_start += local_rows_per_process[p];
      const size_type local_row_end =
        local_row_start + local_rows_per_process[this_process];
 
      // create the matrix. We
      // do not set row length but set the
      // correct SparsityPattern later.
      PetscErrorCode ierr = MatCreate(communicator, &matrix);
      AssertThrow(ierr == 0, ExcPETScError(ierr));
 
      ierr = MatSetSizes(matrix,
                         local_rows_per_process[this_process],
                         local_columns_per_process[this_process],
                         sparsity_pattern.n_rows(),
                         sparsity_pattern.n_cols());
      AssertThrow(ierr == 0, ExcPETScError(ierr));
 
      // Use MATAIJ which dispatches to SEQAIJ
      // if the size of the communicator is 1,
      // and to MPIAIJ otherwise.
      ierr = MatSetType(matrix, MATAIJ);
      AssertThrow(ierr == 0, ExcPETScError(ierr));
 
      // next preset the exact given matrix
      // entries with zeros, if the user
      // requested so. this doesn't avoid any
      // memory allocations, but it at least
      // avoids some searches later on. the
      // key here is that we can use the
      // matrix set routines that set an
      // entire row at once, not a single
      // entry at a time
      //
      // for the usefulness of this option
      // read the documentation of this
      // class.
      if (preset_nonzero_locations == true)
        {
          // MatXXXAIJSetPreallocationCSR
          // can be used to allocate the sparsity
          // pattern of a matrix if it is already
          // available:
 
          // first set up the column number
          // array for the rows to be stored
          // on the local processor. have one
          // dummy entry at the end to make
          // sure petsc doesn't read past the
          // end
          std::vector<PetscInt> rowstart_in_window(local_row_end -
                                                     local_row_start + 1,
                                                   0),
            colnums_in_window;
          {
            size_type n_cols = 0;
            for (size_type i = local_row_start; i < local_row_end; ++i)
              {
                const size_type row_length = sparsity_pattern.row_length(i);
                const auto      row_start =
                  rowstart_in_window[i - local_row_start] + row_length;
                const auto petsc_row_start = static_cast<PetscInt>(row_start);
                AssertIntegerConversion(petsc_row_start, row_start);
                rowstart_in_window[i + 1 - local_row_start] = petsc_row_start;
                n_cols += row_length;
              }
            colnums_in_window.resize(n_cols + 1, -1);
          }
 
          // now copy over the information
          // from the sparsity pattern.
          {
            PetscInt *ptr = colnums_in_window.data();
            for (size_type i = local_row_start; i < local_row_end; ++i)
              for (typename SparsityPatternType::iterator p =
                     sparsity_pattern.begin(i);
                   p != sparsity_pattern.end(i);
                   ++p, ++ptr)
                {
                  const auto petsc_column = static_cast<PetscInt>(p->column());
                  AssertIntegerConversion(petsc_column, p->column());
                  *ptr = petsc_column;
                }
          }
 
 
          // then call the petsc function
          // that summarily allocates these
          // entries.
          // Here we both call the specific API since this is how
          // PETSc polymorphism works. If the matrix is of type MPIAIJ,
          // the second call is dummy. If the matrix is of type SEQAIJ,
          // the first call is dummy.
          ierr = MatSeqAIJSetPreallocationCSR(matrix,
                                              rowstart_in_window.data(),
                                              colnums_in_window.data(),
                                              nullptr);
          ierr = MatMPIAIJSetPreallocationCSR(matrix,
                                              rowstart_in_window.data(),
                                              colnums_in_window.data(),
                                              nullptr);
          AssertThrow(ierr == 0, ExcPETScError(ierr));
 
          close_matrix(matrix);
          set_keep_zero_rows(matrix);
        }
    }
 
    // BDDC
    template <typename SparsityPatternType>
    void
    SparseMatrix::do_reinit(const MPI_Comm             communicator,
                            const IndexSet            &local_rows,
                            const IndexSet            &local_active_rows,
                            const IndexSet            &local_columns,
                            const IndexSet            &local_active_columns,
                            const SparsityPatternType &sparsity_pattern)
    {
      // If the sparsity pattern's dimensions can be converted to PetscInts then
      // the rest of the conversions will succeed
      AssertThrowIntegerConversion(static_cast<PetscInt>(
                                     sparsity_pattern.n_rows()),
                                   sparsity_pattern.n_rows());
      AssertThrowIntegerConversion(static_cast<PetscInt>(
                                     sparsity_pattern.n_cols()),
                                   sparsity_pattern.n_cols());
 
#  if DEAL_II_PETSC_VERSION_GTE(3, 10, 0)
      Assert(sparsity_pattern.n_rows() == local_rows.size(),
             ExcMessage(
               "SparsityPattern and IndexSet have different number of rows."));
      Assert(
        sparsity_pattern.n_cols() == local_columns.size(),
        ExcMessage(
          "SparsityPattern and IndexSet have different number of columns"));
      Assert(local_rows.is_contiguous() && local_columns.is_contiguous(),
             ExcMessage("PETSc only supports contiguous row/column ranges"));
      Assert(local_rows.is_ascending_and_one_to_one(communicator),
             ExcNotImplemented());
 
      if constexpr (running_in_debug_mode())
        {
          // check indexsets
          const types::global_dof_index row_owners =
            Utilities::MPI::sum(local_rows.n_elements(), communicator);
          const types::global_dof_index col_owners =
            Utilities::MPI::sum(local_columns.n_elements(), communicator);
          Assert(
            row_owners == sparsity_pattern.n_rows(),
            ExcMessage(
              std::string(
                "Each row has to be owned by exactly one owner (n_rows()=") +
              std::to_string(sparsity_pattern.n_rows()) +
              " but sum(local_rows.n_elements())=" +
              std::to_string(row_owners) + ")"));
          Assert(
            col_owners == sparsity_pattern.n_cols(),
            ExcMessage(
              std::string(
                "Each column has to be owned by exactly one owner (n_cols()=") +
              std::to_string(sparsity_pattern.n_cols()) +
              " but sum(local_columns.n_elements())=" +
              std::to_string(col_owners) + ")"));
        }
      PetscErrorCode ierr;
 
      // create the local to global mappings as arrays.
      const IndexSet::size_type n_local_active_rows =
        local_active_rows.n_elements();
      const IndexSet::size_type n_local_active_cols =
        local_active_columns.n_elements();
      std::vector<PetscInt> idx_glob_row(n_local_active_rows);
      std::vector<PetscInt> idx_glob_col(n_local_active_cols);
      for (IndexSet::size_type k = 0; k < n_local_active_rows; ++k)
        {
          idx_glob_row[k] = local_active_rows.nth_index_in_set(k);
        }
      for (IndexSet::size_type k = 0; k < n_local_active_cols; ++k)
        {
          idx_glob_col[k] = local_active_columns.nth_index_in_set(k);
        }
 
 
      IS is_glob_row, is_glob_col;
      // Create row index set
      ISLocalToGlobalMapping l2gmap_row;
      ierr = ISCreateGeneral(communicator,
                             n_local_active_rows,
                             idx_glob_row.data(),
                             PETSC_COPY_VALUES,
                             &is_glob_row);
      AssertThrow(ierr == 0, ExcPETScError(ierr));
      ierr = ISLocalToGlobalMappingCreateIS(is_glob_row, &l2gmap_row);
      AssertThrow(ierr == 0, ExcPETScError(ierr));
      ierr = ISDestroy(&is_glob_row);
      AssertThrow(ierr == 0, ExcPETScError(ierr));
      ierr =
        ISLocalToGlobalMappingViewFromOptions(l2gmap_row, nullptr, "-view_map");
      AssertThrow(ierr == 0, ExcPETScError(ierr));
 
      // Create column index set
      ISLocalToGlobalMapping l2gmap_col;
      ierr = ISCreateGeneral(communicator,
                             n_local_active_cols,
                             idx_glob_col.data(),
                             PETSC_COPY_VALUES,
                             &is_glob_col);
      AssertThrow(ierr == 0, ExcPETScError(ierr));
      ierr = ISLocalToGlobalMappingCreateIS(is_glob_col, &l2gmap_col);
      AssertThrow(ierr == 0, ExcPETScError(ierr));
      ierr = ISDestroy(&is_glob_col);
      AssertThrow(ierr == 0, ExcPETScError(ierr));
      ierr =
        ISLocalToGlobalMappingViewFromOptions(l2gmap_col, nullptr, "-view_map");
      AssertThrow(ierr == 0, ExcPETScError(ierr));
 
      // create the matrix with the IS constructor.
      ierr = MatCreateIS(communicator,
                         1,
                         local_rows.n_elements(),
                         local_columns.n_elements(),
                         sparsity_pattern.n_rows(),
                         sparsity_pattern.n_cols(),
                         l2gmap_row,
                         l2gmap_col,
                         &matrix);
      AssertThrow(ierr == 0, ExcPETScError(ierr));
      ierr = ISLocalToGlobalMappingDestroy(&l2gmap_row);
      AssertThrow(ierr == 0, ExcPETScError(ierr));
      ierr = ISLocalToGlobalMappingDestroy(&l2gmap_col);
      AssertThrow(ierr == 0, ExcPETScError(ierr));
 
      // next preset the exact given matrix
      // entries with zeros. This doesn't avoid any
      // memory allocations, but it at least
      // avoids some searches later on. the
      // key here is that we can use the
      // matrix set routines that set an
      // entire row at once, not a single
      // entry at a time.
      //
      // for the usefulness of this option
      // read the documentation of this
      // class.
 
      Mat local_matrix; // In the MATIS case, we use the local matrix instead
      ierr = MatISGetLocalMat(matrix, &local_matrix);
      AssertThrow(ierr == 0, ExcPETScError(ierr));
      ierr = MatSetType(local_matrix,
                        MATSEQAIJ); // SEQ as it is local! TODO: Allow for
                                    // OpenMP parallelization in local node.
      AssertThrow(ierr == 0, ExcPETScError(ierr));
      if (local_rows.n_elements() > 0)
        {
          // MatSEQAIJSetPreallocationCSR
          // can be used to allocate the sparsity
          // pattern of a matrix. Local matrices start from 0 (MATIS).
          const PetscInt local_row_start = 0;
          const PetscInt local_row_end   = local_active_rows.n_elements();
 
          // first set up the column number
          // array for the rows to be stored
          // on the local processor.
          std::vector<PetscInt> rowstart_in_window(local_row_end -
                                                     local_row_start + 1,
                                                   0),
            colnums_in_window;
          unsigned int global_row_index = 0;
          {
            unsigned int n_cols           = 0;
            unsigned int global_row_index = 0;
            for (PetscInt i = local_row_start; i < local_row_end; ++i)
              {
                global_row_index = local_active_rows.nth_index_in_set(i);
                const PetscInt row_length =
                  sparsity_pattern.row_length(global_row_index);
                rowstart_in_window[i + 1 - local_row_start] =
                  rowstart_in_window[i - local_row_start] + row_length;
                n_cols += row_length;
              }
            colnums_in_window.resize(n_cols + 1, -1);
          }
 
 
          // now copy over the information
          // from the sparsity pattern. For this we first invert the column
          // index set.
          std::map<unsigned int, unsigned int> loc_act_cols_inv;
          for (unsigned int i = 0; i < local_active_columns.n_elements(); ++i)
            {
              loc_act_cols_inv[local_active_columns.nth_index_in_set(i)] = i;
            }
 
          {
            PetscInt *ptr = colnums_in_window.data();
            for (PetscInt i = local_row_start; i < local_row_end; ++i)
              {
                global_row_index = local_active_rows.nth_index_in_set(i);
                for (typename SparsityPatternType::iterator p =
                       sparsity_pattern.begin(global_row_index);
                     p != sparsity_pattern.end(global_row_index);
                     ++p, ++ptr)
                  *ptr = loc_act_cols_inv[p->column()];
              }
          }
 
          // then call the petsc function
          // that summarily allocates these
          // entries:
          ierr = MatSeqAIJSetPreallocationCSR(local_matrix,
                                              rowstart_in_window.data(),
                                              colnums_in_window.data(),
                                              nullptr);
          AssertThrow(ierr == 0, ExcPETScError(ierr));
        }
      else
        {
          PetscInt i = 0;
          ierr = MatSeqAIJSetPreallocationCSR(local_matrix, &i, &i, nullptr);
          AssertThrow(ierr == 0, ExcPETScError(ierr));
        }
      compress(VectorOperation::insert);
 
      {
        close_matrix(local_matrix);
        set_keep_zero_rows(local_matrix);
      }
      ierr = MatISRestoreLocalMat(matrix, &local_matrix);
      AssertThrow(ierr == 0, ExcPETScError(ierr));
#  else
      {
        // Use this to avoid unused variables warning
        (void)communicator;
        (void)local_rows;
        (void)local_active_rows;
        (void)local_columns;
        (void)local_active_columns;
        (void)sparsity_pattern;
        AssertThrow(false,
                    ExcMessage(
                      "BDDC preconditioner requires PETSc 3.10.0 or newer"));
      }
#  endif
    }
 
#  ifndef DOXYGEN
    // explicit instantiations
    //
    template SparseMatrix::SparseMatrix(const MPI_Comm,
                                        const SparsityPattern &,
                                        const std::vector<size_type> &,
                                        const std::vector<size_type> &,
                                        const unsigned int,
                                        const bool);
    template SparseMatrix::SparseMatrix(const MPI_Comm,
                                        const DynamicSparsityPattern &,
                                        const std::vector<size_type> &,
                                        const std::vector<size_type> &,
                                        const unsigned int,
                                        const bool);
 
    template void
    SparseMatrix::reinit(const MPI_Comm,
                         const SparsityPattern &,
                         const std::vector<size_type> &,
                         const std::vector<size_type> &,
                         const unsigned int,
                         const bool);
    template void
    SparseMatrix::reinit(const MPI_Comm,
                         const DynamicSparsityPattern &,
                         const std::vector<size_type> &,
                         const std::vector<size_type> &,
                         const unsigned int,
                         const bool);
 
    template void
    SparseMatrix::reinit(const IndexSet &,
                         const SparsityPattern &,
                         const MPI_Comm);
 
    template void
    SparseMatrix::reinit(const IndexSet &,
                         const IndexSet &,
                         const SparsityPattern &,
                         const MPI_Comm);
 
    template void
    SparseMatrix::reinit(const IndexSet &,
                         const DynamicSparsityPattern &,
                         const MPI_Comm);
 
    template void
    SparseMatrix::reinit(const IndexSet &,
                         const IndexSet &,
                         const DynamicSparsityPattern &,
                         const MPI_Comm);
 
    template void
    SparseMatrix::do_reinit(const MPI_Comm,
                            const SparsityPattern &,
                            const std::vector<size_type> &,
                            const std::vector<size_type> &,
                            const unsigned int,
                            const bool);
    template void
    SparseMatrix::do_reinit(const MPI_Comm,
                            const DynamicSparsityPattern &,
                            const std::vector<size_type> &,
                            const std::vector<size_type> &,
                            const unsigned int,
                            const bool);
 
    template void
    SparseMatrix::do_reinit(const MPI_Comm,
                            const IndexSet &,
                            const IndexSet &,
                            const SparsityPattern &);
 
    template void
    SparseMatrix::do_reinit(const MPI_Comm,
                            const IndexSet &,
                            const IndexSet &,
                            const DynamicSparsityPattern &);
 
    template void
    SparseMatrix::reinit(const IndexSet &,
                         const IndexSet &,
                         const IndexSet &,
                         const IndexSet &,
                         const SparsityPattern &,
                         const MPI_Comm);
    template void
    SparseMatrix::reinit(const IndexSet &,
                         const IndexSet &,
                         const IndexSet &,
                         const IndexSet &,
                         const DynamicSparsityPattern &,
                         const MPI_Comm);
 
    template void
    SparseMatrix::do_reinit(const MPI_Comm,
                            const IndexSet &,
                            const IndexSet &,
                            const IndexSet &,
                            const IndexSet &,
                            const SparsityPattern &);
    template void
    SparseMatrix::do_reinit(const MPI_Comm,
                            const IndexSet &,
                            const IndexSet &,
                            const IndexSet &,
                            const IndexSet &,
                            const DynamicSparsityPattern &);
#  endif
 
 
    PetscScalar
    SparseMatrix::matrix_norm_square(const Vector &v) const
    {
      Vector tmp(v);
      vmult(tmp, v);
      // note, that v*tmp returns  sum_i conjugate(v)_i * tmp_i
      return v * tmp;
    }
 
    PetscScalar
    SparseMatrix::matrix_scalar_product(const Vector &u, const Vector &v) const
    {
      Vector tmp(v);
      vmult(tmp, v);
      // note, that v*tmp returns  sum_i conjugate(v)_i * tmp_i
      return u * tmp;
    }
 
    IndexSet
    SparseMatrix::locally_owned_domain_indices() const
    {
      PetscInt       n_rows, n_cols, n_loc_rows, n_loc_cols, min, max;
      PetscErrorCode ierr;
 
      ierr = MatGetSize(matrix, &n_rows, &n_cols);
      AssertThrow(ierr == 0, ExcPETScError(ierr));
 
      ierr = MatGetLocalSize(matrix, &n_loc_rows, &n_loc_cols);
      AssertThrow(ierr == 0, ExcPETScError(ierr));
 
      ierr = MatGetOwnershipRangeColumn(matrix, &min, &max);
      AssertThrow(ierr == 0, ExcPETScError(ierr));
 
      Assert(n_loc_cols == max - min,
             ExcMessage(
               "PETSc is requiring non contiguous memory allocation."));
 
      IndexSet indices(n_cols);
      indices.add_range(min, max);
      indices.compress();
 
      return indices;
    }
 
    IndexSet
    SparseMatrix::locally_owned_range_indices() const
    {
      PetscInt       n_rows, n_cols, n_loc_rows, n_loc_cols, min, max;
      PetscErrorCode ierr;
 
      ierr = MatGetSize(matrix, &n_rows, &n_cols);
      AssertThrow(ierr == 0, ExcPETScError(ierr));
 
      ierr = MatGetLocalSize(matrix, &n_loc_rows, &n_loc_cols);
      AssertThrow(ierr == 0, ExcPETScError(ierr));
 
      ierr = MatGetOwnershipRange(matrix, &min, &max);
      AssertThrow(ierr == 0, ExcPETScError(ierr));
 
      Assert(n_loc_rows == max - min,
             ExcMessage(
               "PETSc is requiring non contiguous memory allocation."));
 
      IndexSet indices(n_rows);
      indices.add_range(min, max);
      indices.compress();
 
      return indices;
    }
 
    void
    SparseMatrix::mmult(SparseMatrix       &C,
                        const SparseMatrix &B,
                        const MPI::Vector  &V) const
    {
      // Simply forward to the protected member function of the base class
      // that takes abstract matrix and vector arguments (to which the compiler
      // automatically casts the arguments).
      MatrixBase::mmult(C, B, V);
    }
 
    void
    SparseMatrix::Tmmult(SparseMatrix       &C,
                         const SparseMatrix &B,
                         const MPI::Vector  &V) const
    {
      // Simply forward to the protected member function of the base class
      // that takes abstract matrix and vector arguments (to which the compiler
      // automatically casts the arguments).
      MatrixBase::Tmmult(C, B, V);
    }
 
  } // namespace MPI
} // namespace PETScWrappers
 
 
 
#endif // DEAL_II_WITH_PETSC
DEAL_II_NAMESPACE_CLOSE