Line data    Source code

       1             : // The libMesh Finite Element Library.
       2             : // Copyright (C) 2002-2026 Benjamin S. Kirk, John W. Peterson, Roy H. Stogner
       3             : 
       4             : // This library is free software; you can redistribute it and/or
       5             : // modify it under the terms of the GNU Lesser General Public
       6             : // License as published by the Free Software Foundation; either
       7             : // version 2.1 of the License, or (at your option) any later version.
       8             : 
       9             : // This library is distributed in the hope that it will be useful,
      10             : // but WITHOUT ANY WARRANTY; without even the implied warranty of
      11             : // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
      12             : // Lesser General Public License for more details.
      13             : 
      14             : // You should have received a copy of the GNU Lesser General Public
      15             : // License along with this library; if not, write to the Free Software
      16             : // Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
      17             : 
      18             : 
      19             : 
      20             : #ifndef LIBMESH_LINEAR_IMPLICIT_SYSTEM_H
      21             : #define LIBMESH_LINEAR_IMPLICIT_SYSTEM_H
      22             : 
      23             : // Local Includes
      24             : #include "libmesh/implicit_system.h"
      25             : 
      26             : // C++ includes
      27             : #include <cstddef>
      28             : #include <optional>
      29             : 
      30             : namespace libMesh
      31             : {
      32             : 
      33             : 
      34             : // Forward Declarations
      35             : template <typename T> class LinearSolver;
      36             : template <typename T> class ShellMatrix;
      37             : class SolverConfiguration;
      38             : 
      39             : /**
      40             :  * Per-call options for LinearImplicitSystem::solve().
      41             :  */
      42             : struct LinearImplicitSystemSolveOptions
      43             : {
      44             :   /**
      45             :    * Solver to use for this call.  A null pointer selects the solver
      46             :    * owned by the system.  The caller retains ownership of a borrowed
      47             :    * solver and must keep it alive for the duration of the call.
      48             :    */
      49             :   LinearSolver<Number> * solver = nullptr;
      50             : 
      51             :   /**
      52             :    * Configuration to attach for this call.  When non-null, the
      53             :    * configuration supplies rel_tol, abs_tol, and max_its.
      54             :    */
      55             :   SolverConfiguration * solver_configuration = nullptr;
      56             : 
      57             :   /**
      58             :    * Per-call assembly policy.  An unset value uses the system's
      59             :    * persistent assemble_before_solve setting.
      60             :    */
      61             :   std::optional<bool> assemble_before_solve;
      62             : };
      63             : 
      64             : /**
      65             :  * \brief Manages consistently variables, degrees of freedom, coefficient
      66             :  * vectors, matrices and linear solvers for implicit systems.
      67             :  *
      68             :  * An implicit system is a system that requires the solution of a
      69             :  * system of equations. This class has the ability to create and use a
      70             :  * linear solver to solve the system.
      71             :  *
      72             :  * The matrix LinearImplicitSystem::matrix and the vector
      73             :  * LinearImplicitSystem::rhs should be filled during assembly.
      74             :  *
      75             :  * \note Additional vectors/matrices can be added via parent class
      76             :  * interfaces.
      77             :  *
      78             :  * \author Benjamin Kirk
      79             :  * \date 2005
      80             :  */
      81        1240 : class LinearImplicitSystem : public ImplicitSystem
      82             : {
      83             : public:
      84             : 
      85             :   /**
      86             :    * Constructor.
      87             :    */
      88             :   LinearImplicitSystem (EquationSystems & es,
      89             :                         const std::string & name,
      90             :                         const unsigned int number);
      91             : 
      92             :   /**
      93             :    * Special functions.
      94             :    * - This class has the same restrictions/defaults as its base class.
      95             :    * - The destructor is defaulted out-of-line.
      96             :    */
      97             :   LinearImplicitSystem (const LinearImplicitSystem &) = delete;
      98             :   LinearImplicitSystem & operator= (const LinearImplicitSystem &) = delete;
      99             :   LinearImplicitSystem (LinearImplicitSystem &&) = default;
     100             :   LinearImplicitSystem & operator= (LinearImplicitSystem &&) = delete;
     101             :   virtual ~LinearImplicitSystem ();
     102             : 
     103             :   /**
     104             :    * The type of system.
     105             :    */
     106             :   typedef LinearImplicitSystem sys_type;
     107             : 
     108             :   /**
     109             :    * The type of the parent.
     110             :    */
     111             :   typedef ImplicitSystem Parent;
     112             : 
     113             :   /**
     114             :    * \returns A reference to *this.
     115             :    */
     116             :   sys_type & system () { return *this; }
     117             : 
     118             :   /**
     119             :    * Clear all the data structures associated with
     120             :    * the system.
     121             :    */
     122             :   virtual void clear () override;
     123             : 
     124             :   /**
     125             :    * Initializes new data members of the system
     126             :    */
     127             :   virtual void init_data () override;
     128             : 
     129             :   /**
     130             :    * Reinitializes the member data fields associated with
     131             :    * the system, so that, e.g., \p assemble() may be used.
     132             :    */
     133             :   virtual void reinit () override;
     134             : 
     135             :   /**
     136             :    * Prepares \p matrix and \p _dof_map for matrix assembly.
     137             :    * Does not actually assemble anything.  For matrix assembly,
     138             :    * use the \p assemble() in derived classes.
     139             :    * Should be overridden in derived classes.
     140             :    */
     141       46122 :   virtual void assemble () override { ImplicitSystem::assemble(); }
     142             : 
     143             :   /**
     144             :    * After calling this method, any solve will be limited to the given
     145             :    * subset.  To disable this mode, call this method with \p subset
     146             :    * being a \p nullptr.
     147             :    */
     148             :   virtual void restrict_solve_to (const SystemSubset * subset,
     149             :                                   const SubsetSolveMode subset_solve_mode=SUBSET_ZERO) override;
     150             : 
     151             :   /**
     152             :    * Assembles & solves the linear system A*x=b.
     153             :    */
     154             :   virtual void solve () override;
     155             : 
     156             :   /**
     157             :    * Optionally assembles and solves the linear system A*x=b using
     158             :    * per-call solver options.
     159             :    */
     160             :   void solve(const LinearImplicitSystemSolveOptions & options);
     161             : 
     162             :   /**
     163             :    * \returns A pointer to a linear solver appropriate for use in
     164             :    * adjoint and/or sensitivity solves
     165             :    */
     166             :   virtual LinearSolver<Number> * get_linear_solver() const override;
     167             : 
     168             :   /**
     169             :    * Assembles a residual in \p rhs and/or a jacobian in \p matrix,
     170             :    * as requested.
     171             :    */
     172             :   virtual void assembly(bool get_residual,
     173             :                         bool get_jacobian,
     174             :                         bool apply_heterogeneous_constraints = false,
     175             :                         bool apply_no_constraints = false) override;
     176             : 
     177             :   /**
     178             :    * \returns \p "LinearImplicit".  Helps in identifying
     179             :    * the system type in an equation system file.
     180             :    */
     181       11580 :   virtual std::string system_type () const override { return "LinearImplicit"; }
     182             : 
     183             :   /**
     184             :    * \returns The number of iterations
     185             :    * taken for the most recent linear solve.
     186             :    */
     187           0 :   unsigned int n_linear_iterations() const { return _n_linear_iterations; }
     188             : 
     189             :   /**
     190             :    * \returns The final residual for the linear system solve.
     191             :    */
     192           0 :   Real final_linear_residual() const { return _final_linear_residual; }
     193             : 
     194             :   /**
     195             :    * This function enables the user to provide a shell matrix, i.e. a
     196             :    * matrix that is not stored element-wise, but as a function.  When
     197             :    * you register your shell matrix using this function, calling \p
     198             :    * solve() will no longer use the \p matrix member but the
     199             :    * registered shell matrix instead.  You can reset this behaviour to
     200             :    * its original state by supplying a \p nullptr to this
     201             :    * function.
     202             :    */
     203             :   void attach_shell_matrix (ShellMatrix<Number> * shell_matrix);
     204             : 
     205             :   /**
     206             :    * Detaches a shell matrix.  Same as \p attach_shell_matrix(nullptr).
     207             :    */
     208             :   void detach_shell_matrix () { attach_shell_matrix(nullptr); }
     209             : 
     210             :   /**
     211             :    * \returns A pointer to the currently attached shell matrix, if any,
     212             :    * otherwise \p nullptr.
     213             :    */
     214             :   ShellMatrix<Number> * get_shell_matrix() { return _shell_matrix; }
     215             : 
     216             :   virtual void create_static_condensation() override;
     217             : 
     218             : protected:
     219             : 
     220             :   /**
     221             :    * The number of linear iterations required to solve the linear
     222             :    * system Ax=b.
     223             :    */
     224             :   unsigned int _n_linear_iterations;
     225             : 
     226             :   /**
     227             :    * The final residual for the linear system Ax=b.
     228             :    */
     229             :   Real _final_linear_residual;
     230             : 
     231             :   /**
     232             :    * User supplies shell matrix or \p nullptr if no shell matrix is used.
     233             :    */
     234             :   ShellMatrix<Number> * _shell_matrix;
     235             : 
     236             :   /**
     237             :    * The current subset on which to solve (or \p nullptr if none).
     238             :    */
     239             :   const SystemSubset * _subset;
     240             : 
     241             :   /**
     242             :    * If restrict-solve-to-subset mode is active, this member decides
     243             :    * what happens with the dofs outside the subset.
     244             :    */
     245             :   SubsetSolveMode _subset_solve_mode;
     246             : };
     247             : 
     248             : } // namespace libMesh
     249             : 
     250             : #endif // LIBMESH_LINEAR_IMPLICIT_SYSTEM_H