Allow requesting static condensation from code

examples/miscellaneous/miscellaneous_ex16/miscellaneous_ex16.C

@@ -87,13 +87,8 @@ Real exact_solution(const Real x, const Real y, const Real z = 0.);
 int
 main(int argc, char ** argv)
 {
-  std::vector<char *> mod_argv(argv, argv + argc);
-  const char * sc_arg = "--Poisson2-static-condensation";
-  mod_argv.push_back(new char[std::strlen(sc_arg) + 1]);
-  std::strcpy(mod_argv.back(), sc_arg);
-
   // Initialize libraries, like in example 2.
-  LibMeshInit init(argc + 1, mod_argv.data());
+  LibMeshInit init(argc, argv);
 
   // This example requires a linear solver package.
   libmesh_example_requires(libMesh::default_solver_package() != INVALID_SOLVER_PACKAGE,
@@ -154,6 +149,7 @@ main(int argc, char ** argv)
   auto & sc_sys = equation_systems.add_system<LinearImplicitSystem>("Poisson2");
   sc_sys.add_variable("u", SECOND);
   sc_sys.attach_assemble_function(assemble_poisson);
+  sc_sys.create_static_condensation();
 
   // Initialize the data structures for the equation system.
   equation_systems.init();
@@ -183,9 +179,6 @@ main(int argc, char ** argv)
 
 #endif // #ifdef LIBMESH_HAVE_VTK
 
-  for (const auto i : make_range(argc, argc + 1))
-    delete[] mod_argv[i];
-
   // All done.
   return 0;
 }

include/systems/implicit_system.h

@@ -337,9 +337,13 @@ class ImplicitSystem : public ExplicitSystem
   mutable std::unique_ptr<LinearSolver<Number>> linear_solver;
 
   /**
-   * Retrieve the static condensation class. Errors if the user has not
-   * requested it on the command line, so calls to this should be guarded by
-   * checking \p has_static_condensation()
+   * Request that static condensation be performed for this system
+   */
+  virtual void create_static_condensation();
+
+  /**
+   * Retrieve the static condensation class. Errors if \p create_static_condensation() has not been
+   * called prior, so calls to this should be guarded by checking \p has_static_condensation()
    */
   StaticCondensation & get_static_condensation();
 

include/systems/linear_implicit_system.h

@@ -181,6 +181,8 @@ class LinearImplicitSystem : public ImplicitSystem
    */
   ShellMatrix<Number> * get_shell_matrix() { return _shell_matrix; }
 
+  virtual void create_static_condensation() override;
+
 protected:
 
   /**

include/systems/nonlinear_implicit_system.h

@@ -316,6 +316,7 @@ class NonlinearImplicitSystem : public ImplicitSystem
    */
   unsigned get_current_nonlinear_iteration_number() const;
 
+  virtual void create_static_condensation() override;
 
 protected:
 

src/systems/implicit_system.C

@@ -48,18 +48,23 @@ ImplicitSystem::ImplicitSystem (EquationSystems & es,
   _sc               (nullptr)
 {
   if (libMesh::on_command_line("--" + name_in + "-static-condensation"))
-    {
-      auto sc = std::make_unique<StaticCondensation>(this->get_mesh(), *this, this->get_dof_map());
-      _sc = sc.get();
-      matrix = &(this->add_matrix ("System Matrix", std::move(sc)));
-      this->get_dof_map().add_static_condensation(*_sc);
-    }
+    this->create_static_condensation();
 }
 
 ImplicitSystem::~ImplicitSystem () = default;
 
 
 
+void ImplicitSystem::create_static_condensation ()
+{
+  auto sc = std::make_unique<StaticCondensation>(this->get_mesh(), *this, this->get_dof_map());
+  _sc = sc.get();
+  matrix = &(this->add_matrix ("System Matrix", std::move(sc)));
+  this->get_dof_map().add_static_condensation(*_sc);
+}
+
+
+
 void ImplicitSystem::clear ()
 {
   // clear the parent data

src/systems/linear_implicit_system.C

@@ -49,8 +49,6 @@ LinearImplicitSystem::LinearImplicitSystem (EquationSystems & es,
   // going to keep using it basically the way we did before it was
   // moved.
   linear_solver = LinearSolver<Number>::build(es.comm());
-  if (_sc)
-    linear_solver->attach_preconditioner(&_sc->get_preconditioner());
 }
 
 
@@ -59,6 +57,14 @@ LinearImplicitSystem::~LinearImplicitSystem () = default;
 
 
 
+void LinearImplicitSystem::create_static_condensation()
+{
+  Parent::create_static_condensation();
+  linear_solver->attach_preconditioner(&_sc->get_preconditioner());
+}
+
+
+
 void LinearImplicitSystem::clear ()
 {
   // clear the linear solver

src/systems/nonlinear_implicit_system.C

@@ -68,6 +68,14 @@ NonlinearImplicitSystem::~NonlinearImplicitSystem () = default;
 
 
 
+void NonlinearImplicitSystem::create_static_condensation()
+{
+  Parent::create_static_condensation();
+  nonlinear_solver->attach_preconditioner(&_sc->get_preconditioner());
+}
+
+
+
 void NonlinearImplicitSystem::clear ()
 {
   // clear the nonlinear solver