C++ GenericMatrix::getrow方法代码示例

//-----------------------------------------------------------------------------
CoordinateMatrix::CoordinateMatrix(const GenericMatrix& A, bool symmetric,
                                   bool base_one)
  : _symmetric(symmetric), _base_one(base_one)
{
  _size[0] = A.size(0);
  _size[1] = A.size(1);

  // Iterate over local rows
  const std::pair<std::size_t, std::size_t> local_row_range = A.local_range(0);
  if (!_symmetric)
  {
    for (std::size_t i = local_row_range.first; i < local_row_range.second; ++i)
    {
      // Get column and value data for row
      std::vector<std::size_t> columns;
      std::vector<double> values;
      A.getrow(i, columns, values);

      // Insert data at end
      _rows.insert(_rows.end(), columns.size(), i);
      _cols.insert(_cols.end(), columns.begin(), columns.end());
      _vals.insert(_vals.end(), values.begin(), values.end());
    }
    assert(_rows.size() == _cols.size());
  }
  else
  {
    assert(_size[0] == _size[1]);
    for (std::size_t i = local_row_range.first; i < local_row_range.second; ++i)
    {
      // Get column and value data for row
      std::vector<std::size_t> columns;
      std::vector<double> values;
      A.getrow(i, columns, values);

      for (std::size_t j = 0; j < columns.size(); ++j)
      {
        if (columns[j] >= i)
        {
          _rows.push_back(i);
          _cols.push_back(columns[j]);
          _vals.push_back(values[j]);
        }
      }
    }
    assert(_rows.size() == _cols.size());
  }

  // Add 1 for Fortran-style indices
  if (base_one)
  {
    for (std::size_t i = 0; i < _cols.size(); ++i)
    {
      _rows[i]++;
      _cols[i]++;
    }
  }
}

  void compute_DG0_to_CG_weight_matrix(GenericMatrix& A, Function& DG)
  {
    compute_weight(DG);

    std::vector<std::size_t> columns;
    std::vector<double> values;
    std::vector<std::vector<std::size_t> > allcolumns;
    std::vector<std::vector<double> > allvalues;
        
    const std::pair<std::size_t, std::size_t> row_range = A.local_range(0);
    const std::size_t m = row_range.second - row_range.first;
    GenericVector& weight = *DG.vector();
    const std::pair<std::size_t, std::size_t> weight_range = weight.local_range();
    std::vector<std::size_t> weight_range_vec(2);
    weight_range_vec[0] = weight_range.first;
    weight_range_vec[1] = weight_range.second;
    int dm = weight_range.second-weight_range.first;
    
    const MPI_Comm mpi_comm = DG.function_space()->mesh()->mpi_comm();
        
    // Communicate local_ranges of weights
    std::vector<std::vector<std::size_t> > all_ranges;
    MPI::all_gather(mpi_comm, weight_range_vec, all_ranges);
    
    // Number of MPI processes
    std::size_t num_processes = MPI::size(mpi_comm);

    // Some weights live on other processes and need to be communicated
    // Create list of off-process weights
    std::vector<std::vector<std::size_t> > dofs_needed(num_processes);    
    for (std::size_t row = 0; row < m; row++)
    {   
      // Get global row number
      const std::size_t global_row = row + row_range.first;
      
      A.getrow(global_row, columns, values);
      
      for (std::size_t i = 0; i < columns.size(); i++)
      {
        std::size_t dof = columns[i];
        if (dof < weight_range.first || dof >= weight_range.second)
        {
          std::size_t owner = dof_owner(all_ranges, dof);
          dofs_needed[owner].push_back(dof);
        }
      }
    }

    // Communicate to all which weights are needed by the process
    std::vector<std::vector<std::size_t> > dofs_needed_recv;
    MPI::all_to_all(mpi_comm, dofs_needed, dofs_needed_recv);
    
    // Fetch the weights that must be communicated
    std::vector<std::vector<double> > weights_to_send(num_processes);    
    for (std::size_t p = 0; p < num_processes; p++)
    {
      if (p == MPI::rank(mpi_comm))  
        continue;
      
      std::vector<std::size_t> dofs = dofs_needed_recv[p];
      std::map<std::size_t, double> send_weights;
      for (std::size_t k = 0; k < dofs.size(); k++)
      {
        weights_to_send[p].push_back(weight[dofs[k]-weight_range.first]);
      }
    }
    std::vector<std::vector<double> > weights_to_send_recv;
    MPI::all_to_all(mpi_comm, weights_to_send, weights_to_send_recv);
    
    // Create a map for looking up received weights
    std::map<std::size_t, double> received_weights;
    for (std::size_t p = 0; p < num_processes; p++)
    {
      if (p == MPI::rank(mpi_comm))
        continue;
      
      for (std::size_t k = 0; k < dofs_needed[p].size(); k++)
      {
        received_weights[dofs_needed[p][k]] = weights_to_send_recv[p][k];         
      }
    }
    
    for (std::size_t row = 0; row < m; row++)
    {   
      // Get global row number
      const std::size_t global_row = row + row_range.first;
      
      A.getrow(global_row, columns, values);
      for (std::size_t i = 0; i < values.size(); i++)
      {
        std::size_t dof = columns[i];
        if (dof < weight_range.first || dof >= weight_range.second)
        {
          values[i] = received_weights[dof];
        }
        else
        {
          values[i] = weight[columns[i]-weight_range.first];  
        }
//        values[i] = 1./values[i];
//.........这里部分代码省略.........

//-----------------------------------------------------------------------------
void DirichletBC::zero_columns(GenericMatrix& A,
                               GenericVector& b,
                               double diag_val) const
{
  // Check arguments
  check_arguments(&A, &b, NULL, 1);

  // A map to hold the mapping from boundary dofs to boundary values
  Map bv_map;
  get_boundary_values(bv_map);

  // Create lookup table of dofs
  //const std::size_t nrows = A.size(0); // should be equal to b.size()
  const std::size_t ncols = A.size(1); // should be equal to max possible dof+1

  std::pair<std::size_t, std::size_t> rows = A.local_range(0);

  std::vector<char> is_bc_dof(ncols);
  std::vector<double> bc_dof_val(ncols);
  for (Map::const_iterator bv = bv_map.begin(); bv != bv_map.end(); ++bv)
  {
    is_bc_dof[bv->first] = 1;
    bc_dof_val[bv->first] = bv->second;
  }

  // Scan through all columns of all rows, setting to zero if
  // is_bc_dof[column]. At the same time, we collect corrections to
  // the RHS

  std::vector<std::size_t> cols;
  std::vector<double> vals;
  std::vector<double> b_vals;
  std::vector<dolfin::la_index> b_rows;

  for (std::size_t row = rows.first; row < rows.second; row++)
  {
    // If diag_val is nonzero, the matrix is a diagonal block
    // (nrows==ncols), and we can set the whole BC row
    if (diag_val != 0.0 && is_bc_dof[row])
    {
      A.getrow(row, cols, vals);
      for (std::size_t j = 0; j < cols.size(); j++)
        vals[j] = (cols[j] == row)*diag_val;
      A.setrow(row, cols, vals);
      A.apply("insert");
      b.setitem(row, bc_dof_val[row]*diag_val);
    }
    else // Otherwise, we scan the row for BC columns
    {
      A.getrow(row, cols, vals);
      bool row_changed = false;
      for (std::size_t j = 0; j < cols.size(); j++)
      {
        const std::size_t col = cols[j];

        // Skip columns that aren't BC, and entries that are zero
        if (!is_bc_dof[col] || vals[j] == 0.0)
          continue;

        // We're going to change the row, so make room for it
        if (!row_changed)
        {
          row_changed = true;
          b_rows.push_back(row);
          b_vals.push_back(0.0);
        }

        b_vals.back() -= bc_dof_val[col]*vals[j];
        vals[j] = 0.0;
      }
      if (row_changed)
      {
        A.setrow(row, cols, vals);
        A.apply("insert");
      }
    }
  }

  b.add_local(&b_vals.front(), b_rows.size(), &b_rows.front());
  b.apply("add");
}