eigen_time_solver.h

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// The libMesh Finite Element Library.
// Copyright (C) 2002-2025 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_EIGEN_TIME_SOLVER_H
#define LIBMESH_EIGEN_TIME_SOLVER_H

#include "libmesh/libmesh_config.h"
#ifdef LIBMESH_HAVE_SLEPC

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

// C++ includes

namespace libMesh
{

// Forward declarations
template <typename T> class EigenSolver;


class EigenTimeSolver : public TimeSolver
{
public:
  typedef DifferentiableSystem sys_type;

  typedef TimeSolver Parent;

  explicit
  EigenTimeSolver (sys_type & s);

  virtual ~EigenTimeSolver ();

  virtual void init () override;

  virtual void reinit () override;

  virtual void solve () override;

  virtual void advance_timestep () override {}

  Real error_order() const { return 0.; }

  virtual bool element_residual (bool get_jacobian,
                                 DiffContext &) override;

  virtual bool side_residual (bool get_jacobian,
                              DiffContext &) override;

  virtual bool nonlocal_residual (bool get_jacobian,
                                  DiffContext &) override;

  virtual Real du (const SystemNorm &) const override { return 0.; }

  virtual bool is_steady() const override { return true; }

  std::unique_ptr<EigenSolver<Number>> eigen_solver;

  double tol;

  unsigned int maxits;

  unsigned int n_eigenpairs_to_compute;

  unsigned int n_basis_vectors_to_use;

  unsigned int n_converged_eigenpairs;

  unsigned int n_iterations_reqd;

private:

  enum NowAssembling {
    Matrix_A,

    Matrix_B,

    Invalid_Matrix
  };

  NowAssembling now_assembling;
};

} // namespace libMesh


#endif // LIBMESH_HAVE_SLEPC
#endif // LIBMESH_EIGEN_TIME_SOLVER_H