petsc_linear_solver.h

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// The libMesh Finite Element Library.
// Copyright (C) 2002-2018 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_PETSC_LINEAR_SOLVER_H
#define LIBMESH_PETSC_LINEAR_SOLVER_H

#include "libmesh/libmesh_config.h"

#ifdef LIBMESH_HAVE_PETSC

#include "libmesh/petsc_macro.h"
#include "libmesh/petsc_solver_exception.h"

// Petsc include files.
#include <petscksp.h>

// Local includes
#include "libmesh/linear_solver.h"

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

//--------------------------------------------------------------------
// Functions with C linkage to pass to PETSc.  PETSc will call these
// methods as needed for preconditioning
//
// Since they must have C linkage they have no knowledge of a namespace.
// Give them an obscure name to avoid namespace pollution.
extern "C"
{
#if PETSC_RELEASE_LESS_THAN(3,0,1)

  PetscErrorCode libmesh_petsc_preconditioner_setup (void * ctx);

  PetscErrorCode libmesh_petsc_preconditioner_apply(void * ctx, Vec x, Vec y);
#else
  PetscErrorCode libmesh_petsc_preconditioner_setup (PC);
  PetscErrorCode libmesh_petsc_preconditioner_apply(PC, Vec x, Vec y);
#endif

#if LIBMESH_ENABLE_DEPRECATED
#if PETSC_RELEASE_LESS_THAN(3,0,1)

  PetscErrorCode __libmesh_petsc_preconditioner_setup (void * ctx);

  PetscErrorCode __libmesh_petsc_preconditioner_apply(void * ctx, Vec x, Vec y);
#else
  PetscErrorCode __libmesh_petsc_preconditioner_setup (PC);
  PetscErrorCode __libmesh_petsc_preconditioner_apply(PC, Vec x, Vec y);
#endif
#endif
} // end extern "C"


namespace libMesh
{

// forward declarations
template <typename T> class PetscMatrix;

template <typename T>
class PetscLinearSolver : public LinearSolver<T>
{
public:
  PetscLinearSolver (const libMesh::Parallel::Communicator & comm_in);

  ~PetscLinearSolver ();

  virtual void clear () override;

  virtual void init (const char * name = nullptr) override;

  void init (PetscMatrix<T> * matrix,
             const char * name = nullptr);

  virtual void init_names (const System &) override;

  virtual void restrict_solve_to (const std::vector<unsigned int> * const dofs,
                                  const SubsetSolveMode subset_solve_mode=SUBSET_ZERO) override;

  virtual std::pair<unsigned int, Real>
  solve (SparseMatrix<T> & matrix_in,
         NumericVector<T> & solution_in,
         NumericVector<T> & rhs_in,
         const double tol,
         const unsigned int m_its) override
  {
    return this->solve(matrix_in, matrix_in, solution_in, rhs_in, tol, m_its);
  }


  virtual std::pair<unsigned int, Real>
  adjoint_solve (SparseMatrix<T> & matrix_in,
                 NumericVector<T> & solution_in,
                 NumericVector<T> & rhs_in,
                 const double tol,
                 const unsigned int m_its) override;

  virtual std::pair<unsigned int, Real>
  solve (SparseMatrix<T> & matrix,
         SparseMatrix<T> & preconditioner,
         NumericVector<T> & solution,
         NumericVector<T> & rhs,
         const double tol,
         const unsigned int m_its) override;

  virtual std::pair<unsigned int, Real>
  solve (const ShellMatrix<T> & shell_matrix,
         NumericVector<T> & solution_in,
         NumericVector<T> & rhs_in,
         const double tol,
         const unsigned int m_its) override;

  virtual std::pair<unsigned int, Real>
  solve (const ShellMatrix<T> & shell_matrix,
         const SparseMatrix<T> & precond_matrix,
         NumericVector<T> & solution_in,
         NumericVector<T> & rhs_in,
         const double tol,
         const unsigned int m_its) override;

  PC pc() { this->init(); return _pc; }

  KSP ksp() { this->init(); return _ksp; }

  void get_residual_history(std::vector<double> & hist);

  Real get_initial_residual();

  virtual LinearConvergenceReason get_converged_reason() const override;

private:

  void set_petsc_solver_type ();

  static PetscErrorCode _petsc_shell_matrix_mult(Mat mat, Vec arg, Vec dest);

  static PetscErrorCode _petsc_shell_matrix_mult_add(Mat mat, Vec arg, Vec add, Vec dest);

  static PetscErrorCode _petsc_shell_matrix_get_diagonal(Mat mat, Vec dest);

  PC _pc;

  KSP _ksp;

  IS _restrict_solve_to_is;

  IS _restrict_solve_to_is_complement;

  PetscInt _restrict_solve_to_is_local_size() const;

  void _create_complement_is (const NumericVector<T> & vec_in);

  SubsetSolveMode _subset_solve_mode;
};


/*----------------------- functions ----------------------------------*/
template <typename T>
inline
PetscLinearSolver<T>::~PetscLinearSolver ()
{
  this->clear ();
}



template <typename T>
inline PetscInt
PetscLinearSolver<T>::_restrict_solve_to_is_local_size() const
{
  libmesh_assert(_restrict_solve_to_is);

  PetscInt s;
  int ierr = ISGetLocalSize(_restrict_solve_to_is, &s);
  LIBMESH_CHKERR(ierr);

  return s;
}



template <typename T>
void
PetscLinearSolver<T>::_create_complement_is (const NumericVector<T> &
#if PETSC_VERSION_LESS_THAN(3,0,0)
                                             // unnamed to avoid compiler "unused parameter" warning
#else
                                             vec_in
#endif
                                             )
{
  libmesh_assert(_restrict_solve_to_is);
#if PETSC_VERSION_LESS_THAN(3,0,0)
  // No ISComplement in PETSc 2.3.3
  libmesh_not_implemented();
#else
  if (_restrict_solve_to_is_complement==nullptr)
    {
      int ierr = ISComplement(_restrict_solve_to_is,
                              vec_in.first_local_index(),
                              vec_in.last_local_index(),
                              &_restrict_solve_to_is_complement);
      LIBMESH_CHKERR(ierr);
    }
#endif
}



} // namespace libMesh


#endif // #ifdef LIBMESH_HAVE_PETSC
#endif // LIBMESH_PETSC_LINEAR_SOLVER_H