continuation_system.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_CONTINUATION_SYSTEM_H
#define LIBMESH_CONTINUATION_SYSTEM_H

// Local Includes
#include "libmesh/fem_system.h"

// C++ includes

namespace libMesh
{

// Forward Declarations
template <typename T> class LinearSolver;
class NewtonSolver;

class ContinuationSystem : public FEMSystem
{
public:
  ContinuationSystem (EquationSystems & es,
                      const std::string & name,
                      const unsigned int number);

  virtual ~ContinuationSystem ();

  typedef ContinuationSystem sys_type;

  typedef FEMSystem Parent;

  virtual void clear () override;

  virtual void solve () override;

  void continuation_solve();

  void advance_arcstep();

  Real * continuation_parameter;

  bool quiet;

  void set_max_arclength_stepsize(Real maxds) { ds=maxds; ds_current=maxds; }

  Real continuation_parameter_tolerance;

  Real solution_tolerance;

  Real initial_newton_tolerance;

  void save_current_solution();

  Real old_continuation_parameter;

  Real min_continuation_parameter;

  Real max_continuation_parameter;

  Real Theta;

  Real Theta_LOCA;

  //Real tau;

  unsigned int n_backtrack_steps;

  unsigned int n_arclength_reductions;

  Real ds_min;

  enum Predictor {
    Euler,

    AB2,

    Invalid_Predictor
  };

  Predictor predictor;

  Real newton_stepgrowth_aggressiveness;

  bool newton_progress_check;

protected:
  virtual void init_data () override;

  enum RHS_Mode {Residual,
                 G_Lambda};

  RHS_Mode rhs_mode;



private:
  void initialize_tangent();

  void solve_tangent();

  void update_solution();

  void set_Theta();

  void set_Theta_LOCA();

  void apply_predictor();

  NumericVector<Number> * du_ds;

  NumericVector<Number> * previous_du_ds;

  NumericVector<Number> * previous_u;

  NumericVector<Number> * y;

  NumericVector<Number> * y_old;

  NumericVector<Number> * z;

  NumericVector<Number> * delta_u;

  std::unique_ptr<LinearSolver<Number>> linear_solver;

  bool tangent_initialized;

  NewtonSolver * newton_solver;

  Real dlambda_ds;

  Real ds;

  Real ds_current;

  Real previous_dlambda_ds;

  Real previous_ds;

  unsigned int newton_step;
};

} // namespace libMesh

#endif // LIBMESH_CONTINUATION_SYSTEM_H