eigen_system.C

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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
 
 
#include "libmesh/libmesh_config.h"
 
// Currently, the EigenSystem should only be available
// if SLEPc support is enabled.
#if defined(LIBMESH_HAVE_SLEPC)
 
// Local includes
#include "libmesh/eigen_system.h"
#include "libmesh/equation_systems.h"
#include "libmesh/sparse_matrix.h"
#include "libmesh/shell_matrix.h"
#include "libmesh/eigen_solver.h"
#include "libmesh/dof_map.h"
#include "libmesh/mesh_base.h"
#include "libmesh/enum_eigen_solver_type.h"
 
namespace libMesh
{
 
 
EigenSystem::EigenSystem (EquationSystems & es,
                          const std::string & name_in,
                          const unsigned int number_in
                          ) :
  Parent           (es, name_in, number_in),
  matrix_A         (nullptr),
  matrix_B         (nullptr),
  precond_matrix   (nullptr),
  eigen_solver     (EigenSolver<Number>::build(es.comm())),
  _n_converged_eigenpairs (0),
  _n_iterations           (0),
  _eigen_problem_type (NHEP),
  _use_shell_matrices (false),
  _use_shell_precond_matrix(false)
{
}
 
 
 
EigenSystem::~EigenSystem () = default;
 
 
 
void EigenSystem::clear ()
{
  // Clear the parent data
  Parent::clear();
 
  // The SparseMatrices are contained in _matrices
  // and are cleared with the above call
  matrix_A = nullptr;
  matrix_B = nullptr;
  precond_matrix = nullptr;
 
  // Operators
  shell_matrix_A.reset();
  shell_matrix_B.reset();
 
  // Preconditioning matrices
  shell_precond_matrix.reset();
 
  // clear the solver
  eigen_solver->clear();
}
 
 
void EigenSystem::set_eigenproblem_type (EigenProblemType ept)
{
  if (!can_add_matrices())
    libmesh_error_msg("ERROR: Cannot change eigen problem type after system initialization");
 
  _eigen_problem_type = ept;
 
  eigen_solver->set_eigenproblem_type(ept);
 
  // libMesh::out << "The Problem type is set to be: " << std::endl;
 
  switch (_eigen_problem_type)
    {
    case HEP:
      // libMesh::out << "Hermitian" << std::endl;
      break;
 
    case NHEP:
      // libMesh::out << "Non-Hermitian" << std::endl;
      break;
 
    case GHEP:
      // libMesh::out << "Generalized Hermitian" << std::endl;
      break;
 
    case GNHEP:
      // libMesh::out << "Generalized Non-Hermitian" << std::endl;
      break;
 
    case GHIEP:
      // libMesh::out << "Generalized indefinite Hermitian" << std::endl;
      break;
 
    default:
      // libMesh::out << "not properly specified" << std::endl;
      libmesh_error_msg("Unrecognized _eigen_problem_type = " << _eigen_problem_type);
    }
}
 
 
 
void EigenSystem::add_matrices ()
{
  Parent::add_matrices();
 
  if (_use_shell_matrices)
  {
    if (!shell_matrix_A)
      shell_matrix_A = ShellMatrix<Number>::build(this->comm());
 
    if (generalized() && !shell_matrix_B)
      shell_matrix_B = ShellMatrix<Number>::build(this->comm());
 
    if (_use_shell_precond_matrix)
      {
        if (!shell_precond_matrix)
          shell_precond_matrix = ShellMatrix<Number>::build(this->comm());
      }
    else if (!precond_matrix)
      precond_matrix = &(this->add_matrix("Eigen Preconditioner"));
  }
  else
  {
    if (!matrix_A)
      matrix_A = &(this->add_matrix("Eigen Matrix A"));
 
    if (generalized() && !matrix_B)
      matrix_B = &(this->add_matrix("Eigen Matrix B"));
  }
}
 
 
 
void EigenSystem::init_matrices ()
{
  Parent::init_matrices();
 
  const bool condense_constraints = condense_constrained_dofs();
  if (shell_matrix_A)
    {
      shell_matrix_A->attach_dof_map(this->get_dof_map());
      if (condense_constraints)
        shell_matrix_A->omit_constrained_dofs();
      shell_matrix_A->init();
    }
 
  if (shell_matrix_B)
    {
      shell_matrix_B->attach_dof_map(this->get_dof_map());
      if (condense_constraints)
        shell_matrix_B->omit_constrained_dofs();
      shell_matrix_B->init();
    }
 
  if (shell_precond_matrix)
    {
      shell_precond_matrix->attach_dof_map(this->get_dof_map());
      if (condense_constraints)
        shell_precond_matrix->omit_constrained_dofs();
      shell_precond_matrix->init();
    }
}
 
 
void EigenSystem::reinit ()
{
  // initialize parent data
  // this calls reinit on matrix_A, matrix_B, and precond_matrix (if any)
  Parent::reinit();
 
  if (shell_matrix_A)
    {
      shell_matrix_A->clear();
      shell_matrix_A->init();
    }
 
  if (shell_matrix_B)
    {
      shell_matrix_B->clear();
      shell_matrix_B->init();
    }
 
  if (shell_precond_matrix)
    {
      shell_precond_matrix->clear();
      shell_precond_matrix->init();
    }
}
 
void
EigenSystem::solve_helper(SparseMatrix<Number> * const A,
                          SparseMatrix<Number> * const B,
                          SparseMatrix<Number> * const P)
{
  // A reference to the EquationSystems
  EquationSystems & es = this->get_equation_systems();
 
  // Get the tolerance for the solver and the maximum
  // number of iterations. Here, we simply adopt the linear solver
  // specific parameters.
  const double tol          =  parameters.have_parameter<Real>("linear solver tolerance") ?
    double(parameters.get<Real>("linear solver tolerance")) :
    double(es.parameters.get<Real>("linear solver tolerance"));
 
  const unsigned int maxits = parameters.have_parameter<unsigned int>("linear solver maximum iterations") ?
    parameters.get<unsigned int>("linear solver maximum iterations") :
    es.parameters.get<unsigned int>("linear solver maximum iterations");
 
  const unsigned int nev    = parameters.have_parameter<unsigned int>("eigenpairs") ?
    parameters.get<unsigned int>("eigenpairs") :
    es.parameters.get<unsigned int>("eigenpairs");
 
  const unsigned int ncv    = parameters.have_parameter<unsigned int>("basis vectors") ?
    parameters.get<unsigned int>("basis vectors") :
    es.parameters.get<unsigned int>("basis vectors");
 
  std::pair<unsigned int, unsigned int> solve_data;
 
  // call the solver depending on the type of eigenproblem
 
  if (_use_shell_matrices)
  {
    // Generalized eigenproblem
    if (generalized())
      // Shell preconditioning matrix
      if (_use_shell_precond_matrix)
        solve_data = eigen_solver->solve_generalized(
            *shell_matrix_A, *shell_matrix_B, *shell_precond_matrix, nev, ncv, tol, maxits);
      else
        solve_data = eigen_solver->solve_generalized(
            *shell_matrix_A, *shell_matrix_B, *P, nev, ncv, tol, maxits);
 
    // Standard eigenproblem
    else
    {
      libmesh_assert(!shell_matrix_B);
      // Shell preconditioning matrix
      if (_use_shell_precond_matrix)
        solve_data = eigen_solver->solve_standard(
            *shell_matrix_A, *shell_precond_matrix, nev, ncv, tol, maxits);
      else
        solve_data = eigen_solver->solve_standard(*shell_matrix_A, *P, nev, ncv, tol, maxits);
    }
  }
  else
  {
    // Generalized eigenproblem
    if (generalized())
      solve_data = eigen_solver->solve_generalized(*A, *B, nev, ncv, tol, maxits);
 
    // Standard eigenproblem
    else
    {
      libmesh_assert(!matrix_B);
      solve_data = eigen_solver->solve_standard(*A, nev, ncv, tol, maxits);
    }
  }
 
  this->_n_converged_eigenpairs = solve_data.first;
  this->_n_iterations           = solve_data.second;
}
 
void EigenSystem::solve ()
{
  if (get_dof_map().n_constrained_dofs())
    libmesh_warning("EigenSystem does not have first-class support for constrained degrees of "
                    "freedom. You may see spurious effects of the constrained degrees of freedom "
                    "in a given eigenvector. If you wish to perform a reliable solve on a system "
                    "with constraints, please use the CondensedEigenSystem class instead");
 
  // check that necessary parameters have been set
  libmesh_assert(
      this->get_equation_systems().parameters.have_parameter<unsigned int>("eigenpairs"));
  libmesh_assert(
      this->get_equation_systems().parameters.have_parameter<unsigned int>("basis vectors"));
 
  if (this->assemble_before_solve)
    // Assemble the linear system
    this->assemble ();
 
  solve_helper(matrix_A, matrix_B, precond_matrix);
}
 
std::pair<Real, Real> EigenSystem::get_eigenpair (dof_id_type i)
{
  // call the eigen_solver get_eigenpair method
  return eigen_solver->get_eigenpair (i, *solution);
}
 
std::pair<Real, Real> EigenSystem::get_eigenvalue (dof_id_type i)
{
  return eigen_solver->get_eigenvalue (i);
}
 
void EigenSystem::set_initial_space (NumericVector<Number> & initial_space_in)
{
  eigen_solver->set_initial_space (initial_space_in);
}
 
 
bool EigenSystem::generalized () const
{
  return _eigen_problem_type == GNHEP ||
         _eigen_problem_type == GHEP ||
         _eigen_problem_type == GHIEP;
}
 
 
const SparseMatrix<Number> & EigenSystem::get_matrix_A() const
{
  libmesh_assert(matrix_A);
  libmesh_assert(!_use_shell_matrices);
  libmesh_assert(has_matrix_A());
  return *matrix_A;
}
 
 
SparseMatrix<Number> & EigenSystem::get_matrix_A()
{
  libmesh_assert(matrix_A);
  libmesh_assert(!_use_shell_matrices);
  libmesh_assert(has_matrix_A());
  return *matrix_A;
}
 
 
const SparseMatrix<Number> & EigenSystem::get_matrix_B() const
{
  libmesh_assert(matrix_B);
  libmesh_assert(!_use_shell_matrices);
  libmesh_assert(generalized());
  libmesh_assert(has_matrix_B());
  return *matrix_B;
}
 
 
SparseMatrix<Number> & EigenSystem::get_matrix_B()
{
  libmesh_assert(matrix_B);
  libmesh_assert(!_use_shell_matrices);
  libmesh_assert(generalized());
  libmesh_assert(has_matrix_B());
  return *matrix_B;
}
 
 
const SparseMatrix<Number> & EigenSystem::get_precond_matrix() const
{
  libmesh_assert(precond_matrix);
  libmesh_assert(_use_shell_matrices);
  libmesh_assert(!_use_shell_precond_matrix);
  libmesh_assert(has_precond_matrix());
  return *precond_matrix;
}
 
 
SparseMatrix<Number> & EigenSystem::get_precond_matrix()
{
  libmesh_assert(precond_matrix);
  libmesh_assert(_use_shell_matrices);
  libmesh_assert(!_use_shell_precond_matrix);
  libmesh_assert(has_precond_matrix());
  return *precond_matrix;
}
 
 
const ShellMatrix<Number> & EigenSystem::get_shell_matrix_A() const
{
  libmesh_assert(_use_shell_matrices);
  libmesh_assert(has_shell_matrix_A());
  return *shell_matrix_A;
}
 
 
ShellMatrix<Number> & EigenSystem::get_shell_matrix_A()
{
  libmesh_assert(_use_shell_matrices);
  libmesh_assert(has_shell_matrix_A());
  return *shell_matrix_A;
}
 
 
const ShellMatrix<Number> & EigenSystem::get_shell_matrix_B() const
{
  libmesh_assert(_use_shell_matrices);
  libmesh_assert(generalized());
  libmesh_assert(has_shell_matrix_B());
  return *shell_matrix_B;
}
 
 
ShellMatrix<Number> & EigenSystem::get_shell_matrix_B()
{
  libmesh_assert(_use_shell_matrices);
  libmesh_assert(generalized());
  libmesh_assert(has_shell_matrix_B());
  return *shell_matrix_B;
}
 
 
const ShellMatrix<Number> & EigenSystem::get_shell_precond_matrix() const
{
  libmesh_assert(_use_shell_matrices);
  libmesh_assert(_use_shell_precond_matrix);
  libmesh_assert(has_shell_precond_matrix());
  return *shell_precond_matrix;
}
 
 
ShellMatrix<Number> & EigenSystem::get_shell_precond_matrix()
{
  libmesh_assert(_use_shell_matrices);
  libmesh_assert(_use_shell_precond_matrix);
  libmesh_assert(has_shell_precond_matrix());
  return *shell_precond_matrix;
}
 
 
bool EigenSystem::has_matrix_A() const
{
  libmesh_assert_equal_to(request_matrix("Eigen Matrix A"), matrix_A);
  return matrix_A;
}
 
 
bool EigenSystem::has_matrix_B() const
{
  libmesh_assert_equal_to(request_matrix("Eigen Matrix B"), matrix_B);
  return matrix_B;
}
 
 
bool EigenSystem::has_precond_matrix() const
{
  libmesh_assert_equal_to(request_matrix("Eigen Preconditioner"), precond_matrix);
  return precond_matrix;
}
 
 
bool EigenSystem::has_shell_matrix_A() const
{
  return shell_matrix_A.get();
}
 
 
bool EigenSystem::has_shell_matrix_B() const
{
  return shell_matrix_B.get();
}
 
 
bool EigenSystem::has_shell_precond_matrix() const
{
  return shell_precond_matrix.get();
}
 
 
const EigenSolver<Number> & EigenSystem::get_eigen_solver() const
{
  libmesh_assert(eigen_solver);
  return *eigen_solver;
}
 
 
EigenSolver<Number> & EigenSystem::get_eigen_solver()
{
  libmesh_assert(eigen_solver);
  return *eigen_solver;
}
 
 
} // namespace libMesh
 
#endif // LIBMESH_HAVE_SLEPC