newton_solver.h

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// The libMesh Finite Element Library.
// Copyright (C) 2002-2026 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_NEWTON_SOLVER_H
#define LIBMESH_NEWTON_SOLVER_H
 
// Local includes
#include "libmesh/libmesh_common.h"
#include "libmesh/linear_solver.h"
#include "libmesh/reference_counted_object.h"
#include "libmesh/diff_solver.h"
 
// C++ includes
 
namespace libMesh
{
 
class NewtonSolver : public DiffSolver
{
public:
  explicit
  NewtonSolver (sys_type & system);
 
  virtual ~NewtonSolver ();
 
  typedef DiffSolver Parent;
 
  virtual void init () override;
 
  virtual void reinit () override;
 
  virtual unsigned int solve () override;
 
  LinearSolver<Number> & get_linear_solver()
  { libmesh_assert(_linear_solver);
    return *_linear_solver;
  }
 
  const LinearSolver<Number> & get_linear_solver() const
  { libmesh_assert(_linear_solver);
    return *_linear_solver;
  }
 
  bool require_residual_reduction;
 
  bool require_finite_residual;
 
  bool brent_line_search;
 
  bool track_linear_convergence;
 
  Real minsteplength;
 
  double linear_tolerance_multiplier;
 
protected:
 
  std::unique_ptr<LinearSolver<Number>> _linear_solver;
 
  Real line_search(Real tol,
                   Real last_residual,
                   Real & current_residual,
                   NumericVector<Number> & newton_iterate,
                   const NumericVector<Number> & linear_solution);
 
  void print_convergence(unsigned int step_num,
                         Real current_residual,
                         Real step_norm,
                         bool linear_solve_finished);
 
  bool test_convergence(Real current_residual,
                        Real step_norm,
                        bool linear_solve_finished);
};
 
 
} // namespace libMesh
 
 
#endif // LIBMESH_NEWTON_SOLVER_H