solver_control.h

// ---------------------------------------------------------------------
//
// Copyright (C) 1998 - 2018 by the deal.II authors
//
// This file is part of the deal.II library.
//
// The deal.II library is free software; you can use it, 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.
// The full text of the license can be found in the file LICENSE.md at
// the top level directory of deal.II.
//
// ---------------------------------------------------------------------

#ifndef dealii_solver_control_h
#define dealii_solver_control_h


#include <deal.II/base/config.h>

#include <deal.II/base/subscriptor.h>

#include <vector>

DEAL_II_NAMESPACE_OPEN

class ParameterHandler;


class SolverControl : public Subscriptor
{
public:
  enum State
  {
    iterate = 0,
    success,
    failure
  };



  class NoConvergence : public ::ExceptionBase
  {
  public:
    NoConvergence(const unsigned int last_step, const double last_residual)
      : last_step(last_step)
      , last_residual(last_residual)
    {}

    virtual ~NoConvergence() noexcept override = default;

    virtual void
    print_info(std::ostream &out) const override
    {
      out
        << "Iterative method reported convergence failure in step " << last_step
        << ". The residual in the last step was " << last_residual << ".\n\n"
        << "This error message can indicate that you have simply not allowed "
        << "a sufficiently large number of iterations for your iterative solver "
        << "to converge. This often happens when you increase the size of your "
        << "problem. In such cases, the last residual will likely still be very "
        << "small, and you can make the error go away by increasing the allowed "
        << "number of iterations when setting up the SolverControl object that "
        << "determines the maximal number of iterations you allow."
        << "\n\n"
        << "The other situation where this error may occur is when your matrix "
        << "is not invertible (e.g., your matrix has a null-space), or if you "
        << "try to apply the wrong solver to a matrix (e.g., using CG for a "
        << "matrix that is not symmetric or not positive definite). In these "
        << "cases, the residual in the last iteration is likely going to be large."
        << std::endl;
    }

    const unsigned int last_step;

    const double last_residual;
  };



  SolverControl(const unsigned int n           = 100,
                const double       tol         = 1.e-10,
                const bool         log_history = false,
                const bool         log_result  = true);

  virtual ~SolverControl() override = default;

  static void
  declare_parameters(ParameterHandler &param);

  void
  parse_parameters(ParameterHandler &param);

  virtual State
  check(const unsigned int step, const double check_value);

  State
  last_check() const;

  double
  initial_value() const;

  double
  last_value() const;

  unsigned int
  last_step() const;

  unsigned int
  max_steps() const;

  unsigned int
  set_max_steps(const unsigned int);

  void
  set_failure_criterion(const double rel_failure_residual);

  void
  clear_failure_criterion();

  double
  tolerance() const;

  double
  set_tolerance(const double);

  void
  enable_history_data();

  const std::vector<double> &
  get_history_data() const;

  double
  average_reduction() const;
  double
  final_reduction() const;

  double
  step_reduction(unsigned int step) const;

  void
  log_history(const bool);

  bool
  log_history() const;

  unsigned int
  log_frequency(unsigned int);

  void
  log_result(const bool);

  bool
  log_result() const;

  DeclException0(ExcHistoryDataRequired);

protected:
  unsigned int maxsteps;

  double tol;

  State lcheck;

  double initial_val;

  double lvalue;

  unsigned int lstep;

  bool check_failure;

  double relative_failure_residual;

  double failure_residual;

  bool m_log_history;

  unsigned int m_log_frequency;

  bool m_log_result;

  bool history_data_enabled;

  std::vector<double> history_data;
};


class ReductionControl : public SolverControl
{
public:
  ReductionControl(const unsigned int maxiter     = 100,
                   const double       tolerance   = 1.e-10,
                   const double       reduce      = 1.e-2,
                   const bool         log_history = false,
                   const bool         log_result  = true);

  ReductionControl(const SolverControl &c);

  ReductionControl &
  operator=(const SolverControl &c);

  virtual ~ReductionControl() override = default;

  static void
  declare_parameters(ParameterHandler &param);

  void
  parse_parameters(ParameterHandler &param);

  virtual State
  check(const unsigned int step, const double check_value) override;

  double
  reduction() const;

  double
  set_reduction(const double);

protected:
  double reduce;

  double reduced_tol;
};

class IterationNumberControl : public SolverControl
{
public:
  IterationNumberControl(const unsigned int maxiter     = 100,
                         const double       tolerance   = 1e-12,
                         const bool         log_history = false,
                         const bool         log_result  = true);

  IterationNumberControl(const SolverControl &c);

  IterationNumberControl &
  operator=(const SolverControl &c);

  virtual ~IterationNumberControl() override = default;

  virtual State
  check(const unsigned int step, const double check_value) override;
};


class ConsecutiveControl : public SolverControl
{
public:
  ConsecutiveControl(const unsigned int maxiter                  = 100,
                     const double       tolerance                = 1.e-10,
                     const unsigned int n_consecutive_iterations = 2,
                     const bool         log_history              = false,
                     const bool         log_result               = false);

  ConsecutiveControl(const SolverControl &c);

  ConsecutiveControl &
  operator=(const SolverControl &c);

  virtual ~ConsecutiveControl() override = default;

  virtual State
  check(const unsigned int step, const double check_value) override;

protected:
  unsigned int n_consecutive_iterations;

  unsigned int n_converged_iterations;
};

//---------------------------------------------------------------------------

#ifndef DOXYGEN

inline unsigned int
SolverControl::max_steps() const
{
  return maxsteps;
}



inline unsigned int
SolverControl::set_max_steps(const unsigned int newval)
{
  unsigned int old = maxsteps;
  maxsteps         = newval;
  return old;
}



inline void
SolverControl::set_failure_criterion(const double rel_failure_residual)
{
  relative_failure_residual = rel_failure_residual;
  check_failure             = true;
}



inline void
SolverControl::clear_failure_criterion()
{
  relative_failure_residual = 0;
  failure_residual          = 0;
  check_failure             = false;
}



inline double
SolverControl::tolerance() const
{
  return tol;
}



inline double
SolverControl::set_tolerance(const double t)
{
  double old = tol;
  tol        = t;
  return old;
}


inline void
SolverControl::log_history(const bool newval)
{
  m_log_history = newval;
}



inline bool
SolverControl::log_history() const
{
  return m_log_history;
}


inline void
SolverControl::log_result(const bool newval)
{
  m_log_result = newval;
}


inline bool
SolverControl::log_result() const
{
  return m_log_result;
}


inline double
ReductionControl::reduction() const
{
  return reduce;
}


inline double
ReductionControl::set_reduction(const double t)
{
  double old = reduce;
  reduce     = t;
  return old;
}

#endif // DOXYGEN

DEAL_II_NAMESPACE_CLOSE

#endif