89 lines
2.9 KiB
C++
89 lines
2.9 KiB
C++
#include <meson_mfem_template/config.hpp>
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#include <mfem.hpp>
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#include <cmath>
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#include <iostream>
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#if !MESON_MFEM_HAS_MPI || !MESON_MFEM_HAS_HYPRE
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#error "This example requires the MPI/Hypre capability"
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#endif
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int main(int argc, char **argv)
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{
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mfem::Mpi::Init(argc, argv);
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mfem::Hypre::Init();
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const int rank = mfem::Mpi::WorldRank();
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const int ranks = mfem::Mpi::WorldSize();
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const char *device_name = argc > 1 ? argv[1] : "cpu";
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mfem::Device device(device_name);
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mfem::Mesh serial_mesh = mfem::Mesh::MakeCartesian2D(
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8, 8, mfem::Element::QUADRILATERAL, true, 1.0, 1.0);
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mfem::Array<int> partitioning(serial_mesh.GetNE());
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for (int element = 0; element < serial_mesh.GetNE(); ++element)
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{
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partitioning[element] = static_cast<long long>(element) * ranks /
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serial_mesh.GetNE();
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}
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mfem::ParMesh mesh(MPI_COMM_WORLD, serial_mesh, partitioning.GetData());
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serial_mesh.Clear();
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mfem::H1_FECollection elements(2, mesh.Dimension());
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mfem::ParFiniteElementSpace space(&mesh, &elements);
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mfem::Array<int> essential_boundary(mesh.bdr_attributes.Max());
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essential_boundary = 1;
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mfem::Array<int> essential_dofs;
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space.GetEssentialTrueDofs(essential_boundary, essential_dofs);
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mfem::ConstantCoefficient one(1.0);
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mfem::ParLinearForm rhs(&space);
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rhs.AddDomainIntegrator(new mfem::DomainLFIntegrator(one));
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rhs.Assemble();
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mfem::ParGridFunction solution(&space);
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solution = 0.0;
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mfem::ParBilinearForm diffusion(&space);
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diffusion.AddDomainIntegrator(new mfem::DiffusionIntegrator(one));
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diffusion.Assemble();
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mfem::OperatorPtr matrix;
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mfem::Vector linear_rhs;
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mfem::Vector linear_solution;
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diffusion.FormLinearSystem(
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essential_dofs, solution, rhs, matrix, linear_solution, linear_rhs);
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mfem::HypreBoomerAMG boomer_amg;
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boomer_amg.SetPrintLevel(0);
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mfem::CGSolver solver(MPI_COMM_WORLD);
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solver.SetPreconditioner(boomer_amg);
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solver.SetOperator(*matrix);
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solver.SetRelTol(1e-10);
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solver.SetAbsTol(0.0);
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solver.SetMaxIter(300);
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solver.SetPrintLevel(0);
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solver.Mult(linear_rhs, linear_solution);
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diffusion.RecoverFEMSolution(linear_solution, rhs, solution);
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#if MESON_MFEM_HAS_GSLIB
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mfem::FindPointsGSLIB find_points(MPI_COMM_WORLD);
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#endif
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#if MESON_MFEM_HAS_SUNDIALS
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mfem::CVODESolver cvode(MPI_COMM_WORLD, CV_BDF);
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#endif
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const double local_norm = solution.Norml2();
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double global_norm = 0.0;
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MPI_Allreduce(&local_norm, &global_norm, 1, MPI_DOUBLE, MPI_SUM,
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MPI_COMM_WORLD);
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if (rank == 0)
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{
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std::cout << "MFEM parallel Poisson: ranks=" << ranks
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<< " global_dofs=" << space.GlobalTrueVSize()
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<< " norm_sum=" << global_norm
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<< " device=" << device_name << '\n';
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}
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return solver.GetConverged() && std::isfinite(global_norm) && global_norm > 0.0
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? 0
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: 2;
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}
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