Functions
int	main (int argc, char **argv)
Function Documentation

◆ main()

int main	(	int	argc,
		char **	argv
	)
Definition at line 64 of file reduced_basis_ex7.C.
 {
   // Initialize libMesh.
   LibMeshInit init (argc, argv);
  
 #ifndef LIBMESH_USE_COMPLEX_NUMBERS
   libmesh_example_requires(false, "--enable-complex");
 #else
  
 #if !defined(LIBMESH_HAVE_XDR)
   // We need XDR support to write out reduced bases
   libmesh_example_requires(false, "--enable-xdr");
 #elif defined(LIBMESH_DEFAULT_SINGLE_PRECISION)
   // XDR binary support requires double precision
   libmesh_example_requires(false, "--disable-singleprecision");
 #elif defined(LIBMESH_DEFAULT_TRIPLE_PRECISION)
   // long double doesn't work on the previous examples, don't try it
   // here
   libmesh_example_requires(false, "double precision");
 #endif
   // FIXME: This example currently segfaults with Trilinos?
   libmesh_example_requires(libMesh::default_solver_package() == PETSC_SOLVERS, "--enable-petsc");
  
 #if LIBMESH_HAVE_PETSC
   // lets parse the input to check which set of arguments was provided.
   // Skip the runs with wrong arguments:
   GetPot input(argc, argv);
  
   // skip if the specification of the solver-package is given in wrong syntax:
 #if PETSC_VERSION_LESS_THAN(3,9,0)
   if (input.search("-pc_factor_mat_solver_type"))
    {
       libMesh::out << "LibMesh was configured with PETSc < 3.9, but command-line options "
                    << "use syntax understood by later versions only. Skipping this example."
                    << std::endl;
       return 77;
    }
 #else
   if (input.search("-pc_factor_mat_solver_package"))
     {
       libMesh::out << "LibMesh was configured with PETSc >= 3.9, but command-line options "
                    << "use deprecated syntax. Skipping now."
                    << std::endl;
       return 77;
     }
 #endif
  
   // check that we have the required solver:
   std::string solver;
   solver = input.next(solver);
   if (solver == "mumps")
   {
 #ifndef LIBMESH_PETSC_HAVE_MUMPS
     libmesh_example_requires(false, "PETSc compiled with MUMPS support");
 #endif
   }
   else if (solver == "superlu")
   {
 #ifndef LIBMESH_PETSC_HAVE_SUPERLU_DIST
     libmesh_example_requires(false, "PETSc compiled with SuperLU support");
 #endif
   }
   else
   {
      libMesh::err << "Error: Solver " << solver << " is unknown."
                   << std::endl;
      return 1;
   }
  
 #endif //LIBMESH_HAVE_PETSC
  
   // Skip this 2D example if libMesh was compiled as 1D-only.
   libmesh_example_requires(2 <= LIBMESH_DIM, "2D support");
  
   // Parse the input file (reduced_basis_ex7.in) using GetPot
   std::string parameters_filename = "reduced_basis_ex7.in";
   GetPot infile(parameters_filename);
  
   const unsigned int dim = 2;                      // The number of spatial dimensions
  
   bool store_basis_functions = infile("store_basis_functions", true); // Do we write the RB basis functions to disk?
  
   // Read the "online_mode" flag from the command line
   GetPot command_line (argc, argv);
   int online_mode = 0;
   if (command_line.search(1, "-online_mode"))
     online_mode = command_line.next(online_mode);
  
   // Create a mesh on the default MPI communicator.
   Mesh mesh(init.comm(), dim);
   mesh.read("horn.msh");
  
   // Create an equation systems object.
   EquationSystems equation_systems (mesh);
  
   // We override RBConstruction with SimpleRBConstruction in order to
   // specialize a few functions for this particular problem.
   SimpleRBConstruction & rb_con =
     equation_systems.add_system<SimpleRBConstruction> ("Acoustics");
  
   // Initialize the data structures for the equation system.
   equation_systems.init ();
  
   // Print out some information about the "truth" discretization
   equation_systems.print_info();
   mesh.print_info();
  
   // Build a new RBEvaluation object which will be used to perform
   // Reduced Basis calculations. This is required in both the
   // "Offline" and "Online" stages.
   SimpleRBEvaluation rb_eval(mesh.comm());
  
   // We need to give the RBConstruction object a pointer to
   // our RBEvaluation object
   rb_con.set_rb_evaluation(rb_eval);
  
   if (!online_mode) // Perform the Offline stage of the RB method
     {
       // Read in the data that defines this problem from the specified text file
       rb_con.process_parameters_file(parameters_filename);
  
       // Print out info that describes the current setup of rb_con
       rb_con.print_info();
  
       // Prepare rb_con for the Construction stage of the RB method.
       // This sets up the necessary data structures and performs
       // initial assembly of the "truth" affine expansion of the PDE.
       rb_con.initialize_rb_construction();
  
       // Compute the reduced basis space by computing "snapshots", i.e.
       // "truth" solves, at well-chosen parameter values and employing
       // these snapshots as basis functions.
       libmesh_try
         {
           rb_con.train_reduced_basis();
         }
       libmesh_catch (LogicError & e)
         {
           libMesh::err << "\n\n"
                        << "********************************************************************************\n"
                        << "Training reduced basis failed, this example requires a direct solver.\n"
                        << "Try running with -ksp_type preonly -pc_type lu instead.\n"
                        << "********************************************************************************"
                        << std::endl;
           return 77;
         }
  
       // Write out the data that will subsequently be required for the Evaluation stage
 #if defined(LIBMESH_HAVE_CAPNPROTO)
       RBDataSerialization::RBEvaluationSerialization rb_eval_writer(rb_con.get_rb_evaluation());
       rb_eval_writer.write_to_file("rb_eval.bin");
 #else
       rb_con.get_rb_evaluation().legacy_write_offline_data_to_files();
 #endif
  
       // If requested, write out the RB basis functions for visualization purposes
       if (store_basis_functions)
         {
           // Write out the basis functions
           rb_con.get_rb_evaluation().write_out_basis_functions(rb_con);
         }
  
       // Basis functions should be orthonormal, so
       // print out the inner products to check this
       rb_con.print_basis_function_orthogonality();
     }
   else // Perform the Online stage of the RB method
     {
       // Read in the reduced basis data
 #if defined(LIBMESH_HAVE_CAPNPROTO)
       RBDataDeserialization::RBEvaluationDeserialization rb_eval_reader(rb_eval);
       rb_eval_reader.read_from_file("rb_eval.bin", /*read_error_bound_data*/ true);
 #else
       rb_eval.legacy_read_offline_data_from_files();
 #endif
  
       // Read in online_N and initialize online parameters
       Real online_frequency = infile("online_frequency", 0.);
       RBParameters online_mu;
       online_mu.set_value("frequency", online_frequency);
       rb_eval.set_parameters(online_mu);
       rb_eval.print_parameters();
  
       // Now do the Online solve using the precomputed reduced basis
       rb_eval.rb_solve(rb_eval.get_n_basis_functions());
  
       if (store_basis_functions)
         {
           // Read in the basis functions
           rb_eval.read_in_basis_functions(rb_con);
  
           // Plot the solution
           rb_con.load_rb_solution();
  
           //Output the variable in ExodusII format (single precision)
           ExodusII_IO(mesh, /*single_precision=*/true).write_equation_systems ("RB_sol_float.exo", equation_systems);
         }
  
       // Now do a sweep over frequencies and write out the reflection coefficient for each frequency
       std::ofstream reflection_coeffs_out("reflection_coefficients.dat");
  
       Real n_frequencies = infile("n_frequencies", 0.);
       Real delta_f = (rb_eval.get_parameter_max("frequency") - rb_eval.get_parameter_min("frequency")) / (n_frequencies-1);
       for (unsigned int freq_i=0; freq_i<n_frequencies; freq_i++)
         {
           Real frequency = rb_eval.get_parameter_min("frequency") + freq_i * delta_f;
           online_mu.set_value("frequency", frequency);
           rb_eval.set_parameters(online_mu);
           rb_eval.rb_solve(rb_eval.get_n_basis_functions());
  
           Number complex_one(1., 0.);
           reflection_coeffs_out << frequency << " " << std::abs(rb_eval.RB_outputs[0] - complex_one) << std::endl;
         }
       reflection_coeffs_out.close();
  
     }
  
 #endif
  
   return 0;
 }
Functions

Function Documentation

◆ main()
