sparse_matrix.h

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// The libMesh Finite Element Library.
// Copyright (C) 2002-2023 Benjamin S. Kirk, John W. Peterson, Roy H. Stogner

// This library is free software; you can redistribute it and/or
// modify it under the terms of the GNU Lesser General Public
// License as published by the Free Software Foundation; either
// version 2.1 of the License, or (at your option) any later version.

// This library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
// Lesser General Public License for more details.

// You should have received a copy of the GNU Lesser General Public
// License along with this library; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA



#ifndef LIBMESH_SPARSE_MATRIX_H
#define LIBMESH_SPARSE_MATRIX_H


// Local includes
#include "libmesh/libmesh.h"
#include "libmesh/libmesh_common.h"
#include "libmesh/reference_counted_object.h"
#include "libmesh/id_types.h"
#include "libmesh/parallel_object.h"
#include "libmesh/enum_parallel_type.h" // PARALLEL
#include "libmesh/enum_matrix_build_type.h" // AUTOMATIC

// C++ includes
#include <cstddef>
#include <iomanip>
#include <vector>
#include <memory>

namespace libMesh
{

// forward declarations
template <typename T> class SparseMatrix;
template <typename T> class DenseMatrix;
class DofMap;
namespace SparsityPattern {
  class Build;
  class Graph;
}
template <typename T> class NumericVector;

// 在定义这个模板辅助函数之前，必须先声明它。
template <typename T>
std::ostream & operator << (std::ostream & os, const SparseMatrix<T> & m);


template <typename T>
class SparseMatrix : public ReferenceCountedObject<SparseMatrix<T>>,
                     public ParallelObject
{
public:
  explicit
  SparseMatrix (const Parallel::Communicator & comm);

  SparseMatrix (SparseMatrix &&) = default;
  SparseMatrix (const SparseMatrix &) = default;
  SparseMatrix & operator= (const SparseMatrix &) = default;
  SparseMatrix & operator= (SparseMatrix &&) = default;
  virtual ~SparseMatrix () = default;

  static std::unique_ptr<SparseMatrix<T>>
  build(const Parallel::Communicator & comm,
        const SolverPackage solver_package = libMesh::default_solver_package(),
        const MatrixBuildType matrix_build_type = MatrixBuildType::AUTOMATIC);

  virtual bool initialized() const { return _is_initialized; }

  void attach_dof_map (const DofMap & dof_map);

  void attach_sparsity_pattern (const SparsityPattern::Build & sp);

  virtual bool need_full_sparsity_pattern() const
  { return false; }

  virtual void update_sparsity_pattern (const SparsityPattern::Graph &) {}

  virtual void init (const numeric_index_type m,
                     const numeric_index_type n,
                     const numeric_index_type m_l,
                     const numeric_index_type n_l,
                     const numeric_index_type nnz=30,
                     const numeric_index_type noz=10,
                     const numeric_index_type blocksize=1) = 0;

  virtual void init (ParallelType type = PARALLEL) = 0;

  virtual void clear () = 0;

  virtual void zero () = 0;

  virtual std::unique_ptr<SparseMatrix<T>> zero_clone () const = 0;

  virtual std::unique_ptr<SparseMatrix<T>> clone () const = 0;

  virtual void zero_rows (std::vector<numeric_index_type> & rows, T diag_value = 0.0);

  virtual void close () = 0;

  virtual void flush () { close(); }

  virtual numeric_index_type m () const = 0;

  virtual numeric_index_type local_m () const { return row_stop() - row_start(); }

  virtual numeric_index_type n () const = 0;

  virtual numeric_index_type row_start () const = 0;

  virtual numeric_index_type row_stop () const = 0;

  virtual void set (const numeric_index_type i,
                    const numeric_index_type j,
                    const T value) = 0;

  virtual void add (const numeric_index_type i,
                    const numeric_index_type j,
                    const T value) = 0;

  virtual void add_matrix (const DenseMatrix<T> & dm,
                           const std::vector<numeric_index_type> & rows,
                           const std::vector<numeric_index_type> & cols) = 0;

  virtual void add_matrix (const DenseMatrix<T> & dm,
                           const std::vector<numeric_index_type> & dof_indices) = 0;

  virtual void add_block_matrix (const DenseMatrix<T> & dm,
                                 const std::vector<numeric_index_type> & brows,
                                 const std::vector<numeric_index_type> & bcols);

  virtual void add_block_matrix (const DenseMatrix<T> & dm,
                                 const std::vector<numeric_index_type> & dof_indices)
  { this->add_block_matrix (dm, dof_indices, dof_indices); }

  virtual void add (const T a, const SparseMatrix<T> & X) = 0;

  virtual void matrix_matrix_mult (SparseMatrix<T> & /*X*/, SparseMatrix<T> & /*Y*/, bool /*reuse*/)
  { libmesh_not_implemented(); }

  virtual void add_sparse_matrix (const SparseMatrix<T> & /*spm*/,
                                  const std::map<numeric_index_type, numeric_index_type> & /*rows*/,
                                  const std::map<numeric_index_type, numeric_index_type> & /*cols*/,
                                  const T /*scalar*/)
  { libmesh_not_implemented(); }

  virtual T operator () (const numeric_index_type i,
                         const numeric_index_type j) const = 0;


  virtual Real l1_norm () const = 0;

  virtual Real linfty_norm () const = 0;

  virtual bool closed() const = 0;

  void print(std::ostream & os=libMesh::out, const bool sparse=false) const;

  friend std::ostream & operator << <>(std::ostream & os, const SparseMatrix<T> & m);

  virtual void print_personal(std::ostream & os=libMesh::out) const = 0;

  virtual void print_matlab(const std::string & /*name*/ = "") const
  {
    libmesh_not_implemented();
  }

  virtual void create_submatrix(SparseMatrix<T> & submatrix,
                                const std::vector<numeric_index_type> & rows,
                                const std::vector<numeric_index_type> & cols) const
  {
    this->_get_submatrix(submatrix,
                         rows,
                         cols,
                         false); // false means DO NOT REUSE submatrix
  }

  virtual void create_submatrix_nosort(SparseMatrix<T> & /*submatrix*/,
                                         const std::vector<numeric_index_type> & /*rows*/,
                                         const std::vector<numeric_index_type> & /*cols*/) const
  {
    libmesh_not_implemented();
  }

  virtual void reinit_submatrix(SparseMatrix<T> & submatrix,
                                const std::vector<numeric_index_type> & rows,
                                const std::vector<numeric_index_type> & cols) const
  {
    this->_get_submatrix(submatrix,
                         rows,
                         cols,
                         true); // true 表示重用 submatrix
  }

  void vector_mult (NumericVector<T> & dest,
                    const NumericVector<T> & arg) const;

  void vector_mult_add (NumericVector<T> & dest,
                        const NumericVector<T> & arg) const;

  virtual void get_diagonal (NumericVector<T> & dest) const = 0;

  virtual void get_transpose (SparseMatrix<T> & dest) const = 0;

  virtual void get_row(numeric_index_type /*i*/,
                       std::vector<numeric_index_type> & /*indices*/,
                       std::vector<T> & /*values*/) const
  {
    libmesh_not_implemented();
  }

protected:

  virtual void _get_submatrix(SparseMatrix<T> & /*submatrix*/,
                              const std::vector<numeric_index_type> & /*rows*/,
                              const std::vector<numeric_index_type> & /*cols*/,
                              const bool /*reuse_submatrix*/) const
  {
    libmesh_not_implemented();
  }

  DofMap const * _dof_map;

  SparsityPattern::Build const * _sp;

  bool _is_initialized;
};



//-----------------------------------------------------------------------
// SparseMatrix 内联成员

// 对于 SGI MIPSpro，此实现必须出现在 print() 成员的完全特化之后。
//
// 通常，更容易在头文件中定义这些 friend 函数。
template <typename T>
std::ostream & operator << (std::ostream & os, const SparseMatrix<T> & m)
{
  m.print(os);
  return os;
}


} // namespace libMesh


#endif // LIBMESH_SPARSE_MATRIX_H