Address Roy's review:

- centralize change in get_linear_solve_parameters
- enable the test
- use the number of iterations for the test

src/systems/frequency_system.C

@@ -343,12 +343,7 @@ void FrequencySystem::solve (const unsigned int n_start,
   // Get the user-specified linear solver tolerance,
   //     the user-specified maximum # of linear solver iterations,
   //     the user-specified wave speed
-  const Real tol            = parameters.have_parameter<Real>("linear solver tolerance") ?
-    double(parameters.get<Real>("linear solver tolerance")) :
-    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 auto [maxits, tol] = this->get_linear_solve_parameters();
 
   // start solver loop
   for (unsigned int n=n_start; n<= n_stop; n++)

src/systems/implicit_system.C

@@ -1222,16 +1222,14 @@ LinearSolver<Number> * ImplicitSystem::get_linear_solver() const
 
 std::pair<unsigned int, Real> ImplicitSystem::get_linear_solve_parameters() const
 {
-  if (parameters.have_parameter<unsigned int>("linear solver maximum iterations") &&
-     parameters.have_parameter<Real>("linear solver tolerance"))
-    return std::make_pair(parameters.get<unsigned int>("linear solver maximum iterations"),
-                          parameters.get<Real>("linear solver tolerance"));
-  else if (!parameters.have_parameter<unsigned int>("linear solver maximum iterations") &&
-     !parameters.have_parameter<Real>("linear solver tolerance"))
-    return std::make_pair(this->get_equation_systems().parameters.get<unsigned int>("linear solver maximum iterations"),
-                          this->get_equation_systems().parameters.get<Real>("linear solver tolerance"));
-  else
-    libmesh_error_msg("ERROR: Insufficient linear solver parameters");
+  return std::make_pair(
+      parameters.have_parameter<unsigned int>("linear solver maximum iterations")
+          ? parameters.get<unsigned int>("linear solver maximum iterations")
+          : this->get_equation_systems().parameters.get<unsigned int>(
+                "linear solver maximum iterations"),
+      parameters.have_parameter<Real>("linear solver tolerance")
+          ? parameters.get<Real>("linear solver tolerance")
+          : this->get_equation_systems().parameters.get<Real>("linear solver tolerance"));
 }
 
 

src/systems/linear_implicit_system.C

@@ -118,10 +118,6 @@ void LinearImplicitSystem::solve ()
     // Assemble the linear system
     this->assemble ();
 
-  // Get a reference to the EquationSystems
-  const EquationSystems & es =
-    this->get_equation_systems();
-
   // If the linear solver hasn't been initialized, we do so here.
   if (libMesh::on_command_line("--solver-system-names"))
     linear_solver->init((this->name()+"_").c_str());
@@ -131,14 +127,7 @@ void LinearImplicitSystem::solve ()
   linear_solver->init_names(*this);
 
   // Get the user-specified linear solver tolerance
-  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"));
-
-  // Get the user-specified maximum # of linear solver iterations
-  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 auto [maxits, tol] = this->get_linear_solve_parameters();
 
   if (_subset != nullptr)
     linear_solver->restrict_solve_to(&_subset->dof_ids(),_subset_solve_mode);

src/systems/nonlinear_implicit_system.C

@@ -147,13 +147,7 @@ void NonlinearImplicitSystem::set_solver_parameters ()
     double(es.parameters.get<Real>("nonlinear solver relative step tolerance"));
 
   // Get the user-specified linear solver tolerances
-  const unsigned int maxlinearits = 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 double linear_tol = parameters.have_parameter<Real>("linear solver tolerance") ?
-    double(parameters.get<Real>("linear solver tolerance")) :
-    double(es.parameters.get<Real>("linear solver tolerance"));
+  const auto [maxlinearits, linear_tol] = this->get_linear_solve_parameters();
 
   const double linear_min_tol = parameters.have_parameter<Real>("linear solver minimum tolerance") ?
     double(parameters.get<Real>("linear solver minimum tolerance")) :

tests/systems/systems_test.C

@@ -472,6 +472,7 @@ public:
   CPPUNIT_TEST( test3DProjectVectorFEHex20 );
   CPPUNIT_TEST( test3DProjectVectorFEHex27 );
 #ifdef LIBMESH_HAVE_SOLVER
+  CPPUNIT_TEST( testSetSystemParameterOverEquationSystem);
   CPPUNIT_TEST( testAssemblyWithDgFemContext );
 #endif
 #endif // LIBMESH_DIM > 2
@@ -1289,8 +1290,9 @@ public:
     // Create an equation systems object.
     EquationSystems equation_systems (mesh);
 
-    // Set some parameters to the equation system that would cause a failed solve
+    // Set some parameters to the equation system that would cause a failed test
     equation_systems.parameters.set<unsigned int>("linear solver maximum iterations") = 0;
+    equation_systems.parameters.set<unsigned int>("nonlinear solver absolute residual tolerance") = 1e8;
 
     // Setup Linear Implicit system
     LinearImplicitSystem & li_system =
@@ -1309,25 +1311,23 @@ public:
     nli_system.add_variable ("v", libMesh::FIRST);
     nli_system.add_variable ("w", libMesh::FIRST);
     nli_system.attach_assemble_function (assemble_matrix_and_rhs);
-    nli_system.get_linear_solver()->set_solver_type(JACOBI);
-    nli_system.get_linear_solver()->set_preconditioner_type(IDENTITY_PRECOND);
 
     // Set some parameters to the system that work for the solve
-    li_system.parameters.set<unsigned int>("linear solver maximum iterations") = 100;
-    nli_system.parameters.set<unsigned int>("linear solver maximum iterations") = 100;
+    li_system.parameters.set<unsigned int>("linear solver maximum iterations") = 5;
+    nli_system.parameters.set<unsigned int>("nonlinear solver absolute residual tolerance") = 1e-10;
 
     // See the solve pass, indicating system parameters are used over equation system parameters
     equation_systems.init ();
     li_system.solve();
     nli_system.solve();
 
-    // We set the solution to be 1 everywhere, so the final l1 norm of the
-    // solution is the product of the number of variables and number of nodes.
-    Real ref_l1_norm = static_cast<Real>(mesh.n_nodes() * li_system.n_vars());
+    // Check that the number of iterations from the systems got obeyed
+    CPPUNIT_ASSERT_EQUAL(li_system.n_linear_iterations(), 5u);
 
-    LIBMESH_ASSERT_FP_EQUAL(li_system.solution->l1_norm(), ref_l1_norm, TOLERANCE*TOLERANCE);
-    LIBMESH_ASSERT_FP_EQUAL(nli_system.solution->l1_norm(), ref_l1_norm, TOLERANCE*TOLERANCE);
-  }
+    // Check that the solution for the nonlinear system is converged
+    Real ref_l1_norm = static_cast<Real>(mesh.n_nodes() * li_system.n_vars());
+    LIBMESH_ASSERT_FP_EQUAL(nli_system.solution->l1_norm(), ref_l1_norm, TOLERANCE);
+}
 
   void testAssemblyWithDgFemContext()
   {