278 lines
7.9 KiB
C++
278 lines
7.9 KiB
C++
// Copyright (c) 2010-2025, Lawrence Livermore National Security, LLC. Produced
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// at the Lawrence Livermore National Laboratory. All Rights reserved. See files
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// LICENSE and NOTICE for details. LLNL-CODE-806117.
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//
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// This file is part of the MFEM library. For more information and source code
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// availability visit https://mfem.org.
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//
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// MFEM is free software; you can redistribute it and/or modify it under the
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// terms of the BSD-3 license. We welcome feedback and contributions, see file
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// CONTRIBUTING.md for details.
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//
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// MFEM test - mesh I/O using the parallel mesh format
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//
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// Compile with: make ex1p
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//
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// Sample runs:
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//
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// The following sample runs alternate between the following two modes:
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//
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// 1. (serial mode) Read a serial mesh, refine it (before and after parallel
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// partitioning), solve a diffusion problem, and write the result, mesh
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// and solution, using a VisItDataCollection using the parallel format for
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// the mesh.
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// 2. (parallel mode) Read a VisItDataCollection saved using the parallel
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// mesh format, then solve the same diffusion problem as above and compare
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// the result to the saved solution.
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//
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// (This sequence is used to support testing with the script sample-runs.sh)
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//
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// mpirun -np 4 ex1p -m ../../data/star.mesh
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// mpirun -np 4 ex1p
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// mpirun -np 4 ex1p -m ../../data/square-disc.mesh
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// mpirun -np 4 ex1p
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// mpirun -np 4 ex1p -m ../../data/star-mixed.mesh
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// mpirun -np 4 ex1p
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// mpirun -np 4 ex1p -m ../../data/escher.mesh
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// mpirun -np 4 ex1p
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// mpirun -np 4 ex1p -m ../../data/fichera.mesh
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// mpirun -np 4 ex1p
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// mpirun -np 4 ex1p -m ../../data/fichera-mixed.mesh
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// mpirun -np 4 ex1p
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#include "mfem.hpp"
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#include <fstream>
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#include <iostream>
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using namespace std;
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using namespace mfem;
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int main(int argc, char *argv[])
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{
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// 1. Initialize MPI and HYPRE.
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Mpi::Init(argc, argv);
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int num_procs = Mpi::WorldSize();
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int myid = Mpi::WorldRank();
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Hypre::Init();
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// 2. Parse command-line options.
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const char *not_set = "(not set)";
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const char *mesh_file = not_set;
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const char *coll_name = "ex1p-dc";
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int order = 1;
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int serial_ref_levels = 1;
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int parallel_ref_levels = 2;
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bool visualization = 1;
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OptionsParser args(argc, argv);
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args.AddOption(&mesh_file, "-m", "--mesh",
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"Mesh file to use.");
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args.AddOption(&coll_name, "-n", "--collection-name",
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"Set the data collection name to use.");
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args.AddOption(&order, "-o", "--order",
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"Finite element order (polynomial degree) or -1 for"
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" isoparametric space.");
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args.AddOption(&serial_ref_levels, "-rs", "--refine-serial",
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"Number of uniform refinements of the mesh before parallel"
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" decomposition.");
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args.AddOption(¶llel_ref_levels, "-rp", "--refine-parallel",
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"Number of uniform refinements to perform after parallel"
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" decomposition.\n\t" "This is the number of levels used for"
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" the convergence study.");
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args.AddOption(&visualization, "-vis", "--visualization", "-no-vis",
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"--no-visualization",
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"Enable or disable GLVis visualization.");
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args.Parse();
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if (!args.Good())
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{
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if (myid == 0)
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{
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args.PrintUsage(cout);
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}
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return 1;
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}
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if (myid == 0)
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{
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args.PrintOptions(cout);
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}
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const bool serial_mode = (mesh_file != not_set);
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ParMesh *pmesh;
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VisItDataCollection visit_dc(MPI_COMM_WORLD, coll_name);
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if (serial_mode)
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{
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// 3. Read the serial mesh on all processors, refine it in serial, then
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// partition it across all processors and refine it in parallel.
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Mesh *mesh = new Mesh(mesh_file, 1, 1);
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for (int l = 0; l < serial_ref_levels; l++)
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{
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mesh->UniformRefinement();
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}
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pmesh = new ParMesh(MPI_COMM_WORLD, *mesh);
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delete mesh;
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for (int l = 0; l < parallel_ref_levels; l++)
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{
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pmesh->UniformRefinement();
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}
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visit_dc.SetMesh(pmesh);
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}
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else
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{
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// 4. Read the given data collection.
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visit_dc.Load();
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if (visit_dc.Error())
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{
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if (myid == 0)
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{
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cout << "Error loading data collection: " << coll_name << endl;
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}
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return 1;
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}
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pmesh = dynamic_cast<ParMesh*>(visit_dc.GetMesh());
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if (pmesh == NULL)
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{
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if (myid == 0)
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{
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cout << "The given data collection does not have a parallel mesh."
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<< endl;
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}
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return 2;
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}
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}
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int dim = pmesh->Dimension();
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// 5. Solve a simple diffusion problem on the parallel mesh.
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FiniteElementCollection *fec;
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if (order > 0)
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{
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fec = new H1_FECollection(order, dim);
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}
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else if (pmesh->GetNodes())
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{
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fec = pmesh->GetNodes()->OwnFEC();
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if (myid == 0)
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{
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cout << "Using isoparametric FEs: " << fec->Name() << endl;
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}
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}
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else
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{
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fec = new H1_FECollection(order = 1, dim);
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}
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ParFiniteElementSpace *fespace = new ParFiniteElementSpace(pmesh, fec);
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HYPRE_BigInt size = fespace->GlobalTrueVSize();
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if (myid == 0)
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{
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cout << "Number of finite element unknowns: " << size << endl;
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}
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Array<int> ess_tdof_list;
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if (pmesh->bdr_attributes.Size())
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{
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Array<int> ess_bdr(pmesh->bdr_attributes.Max());
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ess_bdr = 1;
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fespace->GetEssentialTrueDofs(ess_bdr, ess_tdof_list);
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}
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ParLinearForm *b = new ParLinearForm(fespace);
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ConstantCoefficient one(1.0);
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b->AddDomainIntegrator(new DomainLFIntegrator(one));
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b->Assemble();
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ParGridFunction x(fespace);
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x = 0.0;
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ParBilinearForm *a = new ParBilinearForm(fespace);
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a->AddDomainIntegrator(new DiffusionIntegrator(one));
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a->Assemble();
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HypreParMatrix A;
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Vector B, X;
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a->FormLinearSystem(ess_tdof_list, x, *b, A, X, B);
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if (myid == 0)
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{
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cout << "Size of linear system: " << A.GetGlobalNumRows() << endl;
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}
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HypreBoomerAMG *amg = new HypreBoomerAMG;
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amg->SetPrintLevel(0);
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amg->SetOperator(A);
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HyprePCG *pcg = new HyprePCG(A);
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pcg->SetTol(1e-12);
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pcg->SetMaxIter(200);
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pcg->SetPrintLevel(5);
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pcg->SetPreconditioner(*amg);
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pcg->Mult(B, X);
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a->RecoverFEMSolution(X, *b, x);
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if (serial_mode)
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{
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// 6. Save the parallel mesh and the solution using the data collection.
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visit_dc.RegisterField("temperature", &x);
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visit_dc.SetFormat(DataCollection::PARALLEL_FORMAT);
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visit_dc.SetPrecision(16);
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if (myid == 0)
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{
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cout << "\nSaving data collection '" << coll_name << "' ..." << flush;
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}
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visit_dc.Save();
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if (myid == 0)
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{
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cout << " done.\n" << endl;
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}
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}
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else
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{
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ParGridFunction *saved_x = visit_dc.GetParField("temperature");
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if (!saved_x)
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{
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if (myid == 0)
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{
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cout << "The given data collection has no 'temperature' field."
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<< endl;
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}
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}
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else
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{
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ParGridFunction error(fespace);
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subtract(x, *saved_x, error);
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ConstantCoefficient zero(0.0);
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double err_norm = error.ComputeL2Error(zero);
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if (myid == 0)
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{
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cout << "\n|| x - x_saved ||_L2 = " << err_norm << '\n' << endl;
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}
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}
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}
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// 7. Send the solution by socket to a GLVis server.
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if (visualization)
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{
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char vishost[] = "localhost";
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int visport = 19916;
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socketstream sol_sock(vishost, visport);
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sol_sock << "parallel " << num_procs << " " << myid << "\n";
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sol_sock.precision(8);
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sol_sock << "solution\n" << *pmesh << x << flush;
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}
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// 8. Free the used memory.
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delete pcg;
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delete amg;
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delete a;
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delete b;
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delete fespace;
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if (order > 0) { delete fec; }
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if (serial_mode) { delete pmesh; }
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return 0;
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}
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