Merge remote-tracking branch 'origin/eigensolvers-dev' into arpack-dev

# Conflicts:
#	linalg/eigensolvers.hpp

config/config.hpp.in

@@ -97,6 +97,9 @@
 // Enable MFEM functionality based on the SuiteSparse library.
 // #define MFEM_USE_SUITESPARSE
 
+// Enable MFEM functionality based on the ARPACK library.
+// #define MFEM_USE_ARPACK
+
 // Enable MFEM functionality based on the SuperLU_DIST library.
 // #define MFEM_USE_SUPERLU
 // #define MFEM_USE_SUPERLU5

config/config.mk.in

@@ -32,6 +32,7 @@ MFEM_USE_MEMALLOC      = @MFEM_USE_MEMALLOC@
 MFEM_TIMER_TYPE        = @MFEM_TIMER_TYPE@
 MFEM_USE_SUNDIALS      = @MFEM_USE_SUNDIALS@
 MFEM_USE_SUITESPARSE   = @MFEM_USE_SUITESPARSE@
+MFEM_USE_ARPACK        = @MFEM_USE_ARPACK@
 MFEM_USE_SUPERLU       = @MFEM_USE_SUPERLU@
 MFEM_USE_SUPERLU5      = @MFEM_USE_SUPERLU5@
 MFEM_USE_MUMPS         = @MFEM_USE_MUMPS@

config/defaults.mk

@@ -178,6 +178,7 @@ MFEM_USE_ALGOIM        = NO
 MFEM_USE_UMPIRE        = NO
 MFEM_USE_SIMD          = NO
 MFEM_USE_ADIOS2        = NO
+MFEM_USE_ARPACK        = NO
 MFEM_USE_MKL_CPARDISO  = NO
 MFEM_USE_MKL_PARDISO   = NO
 MFEM_USE_MOONOLITH     = NO
@@ -427,6 +428,14 @@ NETCDF_LIB = $(XLINKER)-rpath,$(NETCDF_DIR)/lib -L$(NETCDF_DIR)/lib\
  $(XLINKER)-rpath,$(HDF5_DIR)/lib -L$(HDF5_DIR)/lib\
  -lnetcdf -lhdf5_hl -lhdf5 $(ZLIB_LIB)
 
+# ARPACK library configuration
+ARPACK_DIR = @MFEM_DIR@/../ARPACK
+ifeq ($(MFEM_USE_MPI),YES)
+ARPACK_LIB = -L$(ARPACK_DIR) -lparpack -larpack
+else
+ARPACK_LIB = -L$(ARPACK_DIR) -larpack
+endif
+
 # PETSc library configuration (version greater or equal to 3.8 or the dev branch)
 PETSC_ARCH := arch-linux2-c-debug
 PETSC_DIR  := $(MFEM_DIR)/../petsc/$(PETSC_ARCH)

examples/CMakeLists.txt

@@ -49,6 +49,13 @@ list(APPEND ALL_EXE_SRCS
   ex41.cpp
   )
 
+if (MFEM_USE_ARPACK)
+list(APPEND ALL_EXE_SRCS
+  ex11.pp
+  ex13.pp
+)
+endif()
+
 if (MFEM_USE_MPI)
   list(APPEND ALL_EXE_SRCS
     ex0p.cpp

examples/ex11.cpp

@@ -0,0 +1,298 @@
+//                       MFEM Example 11 - Serial Version
+//
+// Compile with: make ex11
+//
+// Sample runs:  ex11 -m ../data/square-disc.mesh
+//               ex11 -m ../data/star.mesh
+//               ex11 -m ../data/star-mixed.mesh
+//               ex11 -m ../data/periodic-annulus-sector.msh
+//               ex11 -m ../data/square-disc-p2.vtk -o 2
+//               ex11 -m ../data/square-disc-p3.mesh -o 3
+//               ex11 -m ../data/square-disc-nurbs.mesh -o -1
+//               ex11 -m ../data/disc-nurbs.mesh -o -1 -n 20
+//               ex11 -m ../data/star-surf.mesh
+//               ex11 -m ../data/square-disc-surf.mesh
+//               ex11 -m ../data/inline-segment.mesh
+//               ex11 -m ../data/inline-quad.mesh
+//               ex11 -m ../data/inline-tri.mesh
+//               ex11 -m ../data/amr-quad.mesh
+//               ex11 -m ../data/amr-hex.mesh
+//               ex11 -m ../data/mobius-strip.mesh -n 8
+//
+// Description:  This example code demonstrates the use of MFEM to solve the
+//               eigenvalue problem -Delta u = lambda u with homogeneous
+//               Dirichlet boundary conditions.
+//
+//               We compute a number of the lowest eigenmodes by discretizing
+//               the Laplacian and Mass operators using a FE space of the
+//               specified order, or an isoparametric/isogeometric space if
+//               order < 1 (quadratic for quadratic curvilinear mesh, NURBS for
+//               NURBS mesh, etc.)
+//
+//               The example highlights the use of the ARPACK eigenvalue solver
+//               (regular inverse mode). Reusing a single GLVis visualization
+//               window for multiple eigenfunctions is also illustrated.
+//
+//               We recommend viewing Example 1 before viewing this example.
+
+#include "mfem.hpp"
+#include <fstream>
+#include <iostream>
+
+using namespace std;
+using namespace mfem;
+
+#ifdef MFEM_USE_ARPACK
+
+int main(int argc, char *argv[])
+{
+   // 1. Parse command-line options.
+   const char *mesh_file = "../data/star.mesh";
+   int ser_ref_levels = 3;
+   int order = 1;
+   int nev = 5;
+   double dbc_eig = 1e3;
+   bool visualization = 1;
+   bool arp_solver = true;
+
+   OptionsParser args(argc, argv);
+   args.AddOption(&mesh_file, "-m", "--mesh",
+                  "Mesh file to use.");
+   args.AddOption(&ser_ref_levels, "-rs", "--refine-serial",
+                  "Number of times to refine the mesh uniformly in serial.");
+   args.AddOption(&order, "-o", "--order",
+                  "Finite element order (polynomial degree) or -1 for"
+                  " isoparametric space.");
+   args.AddOption(&nev, "-n", "--num-eigs",
+                  "Number of desired eigenmodes.");
+   args.AddOption(&dbc_eig, "-d", "--dbc-eig",
+                  "Eigenvalues associated with Dirichlet BC "
+                  "(should be larger than the maximum desired eigenvalue).");
+   args.AddOption(&visualization, "-vis", "--visualization", "-no-vis",
+                  "--no-visualization",
+                  "Enable or disable GLVis visualization.");
+   args.Parse();
+   if (!args.Good())
+   {
+      args.PrintUsage(cout);
+      return 1;
+   }
+   args.PrintOptions(cout);
+
+   // 2. Read the (serial) mesh from the given mesh file on all processors. We
+   //    can handle triangular, quadrilateral, tetrahedral, hexahedral, surface
+   //    and volume meshes with the same code.
+   Mesh *mesh;
+   ifstream imesh(mesh_file);
+   if (!imesh)
+   {
+      cerr << "\nCan not open mesh file: " << mesh_file << '\n' << endl;
+      return 2;
+   }
+   mesh = new Mesh(imesh, 1, 1);
+   imesh.close();
+   int dim = mesh->Dimension();
+
+   // 3. Refine the serial mesh on all processors to increase the resolution. In
+   //    this example we do 'ref_levels' of uniform refinement (2 by default, or
+   //    specified on the command line with -rs).
+   for (int lev = 0; lev < ser_ref_levels; lev++)
+   {
+      mesh->UniformRefinement();
+   }
+
+   // 4. Define a finite element space on the mesh. Here we
+   //    use continuous Lagrange finite elements of the specified order. If
+   //    order < 1, we instead use an isoparametric/isogeometric space.
+   FiniteElementCollection *fec;
+   if (order > 0)
+   {
+      fec = new H1_FECollection(order, dim);
+   }
+   else if (mesh->GetNodes())
+   {
+      fec = mesh->GetNodes()->OwnFEC();
+   }
+   else
+   {
+      fec = new H1_FECollection(order = 1, dim);
+   }
+   FiniteElementSpace *fespace = new FiniteElementSpace(mesh, fec);
+   int size = fespace->GetVSize();
+
+   cout << "Number of unknowns: " << size << endl;
+
+   // 5. Set up the parallel bilinear forms a(.,.) and m(.,.) on the finite
+   //    element space. The first corresponds to the Laplacian operator -Delta,
+   //    while the second is a simple mass matrix needed on the right hand side
+   //    of the generalized eigenvalue problem below. The boundary conditions
+   //    are implemented by elimination with special values on the diagonal to
+   //    shift the Dirichlet eigenvalues out of the computational range. After
+   //    serial and parallel assembly we extract the corresponding parallel
+   //    matrices A and M.
+   ConstantCoefficient one(1.0);
+   Array<int> ess_bdr;
+   if (mesh->bdr_attributes.Size())
+   {
+      ess_bdr.SetSize(mesh->bdr_attributes.Max());
+      ess_bdr = 1;
+   }
+
+   BilinearForm *a = new BilinearForm(fespace);
+   a->AddDomainIntegrator(new DiffusionIntegrator(one));
+   if (mesh->bdr_attributes.Size() == 0)
+   {
+      // Add a mass term if the mesh has no boundary, e.g. periodic mesh or
+      // closed surface.
+      a->AddDomainIntegrator(new MassIntegrator(one));
+   }
+   a->Assemble();
+   if (mesh->bdr_attributes.Size() != 0)
+   {
+      a->EliminateEssentialBCDiag(ess_bdr, dbc_eig);
+   }
+   a->Finalize();
+
+   BilinearForm *m = new BilinearForm(fespace);
+   m->AddDomainIntegrator(new MassIntegrator(one));
+   m->Assemble();
+   if (mesh->bdr_attributes.Size() != 0)
+   {
+      // shift the eigenvalue corresponding to eliminated dofs to a large value
+      m->EliminateEssentialBCDiag(ess_bdr, 1.0);
+   }
+   m->Finalize();
+
+   Solver       * solver = NULL;
+
+#ifndef MFEM_USE_SUITESPARSE
+   // 6. Define a simple symmetric Gauss-Seidel preconditioner and use it to
+   //    solve the system A X = B with PCG.
+   cout << "Building CGSolver" << endl;
+   GSSmoother M(m->SpMat());
+   CGSolver * cg_solver = new CGSolver;
+   cg_solver->SetPreconditioner(M);
+   cg_solver->SetRelTol(1.0e-12);
+   solver = cg_solver;
+#else
+   // 7. If MFEM was compiled with SuiteSparse, use UMFPACK to solve the system.
+   cout << "Building UMFPackSolver" << endl;
+   UMFPackSolver * umf_solver = new UMFPackSolver;
+   umf_solver->Control[UMFPACK_ORDERING] = UMFPACK_ORDERING_METIS;
+   solver = umf_solver;
+#endif
+   solver->SetOperator(m->SpMat());
+
+   // 7. Define and configure the ARPACK eigensolver
+   SymGenEigensolver * eig_solver = NULL;
+
+   if (arp_solver)
+   {
+      // ArPackSymGen * arpack = new ArPackSymGen();
+      ArPackSAUPD * arpack = new ArPackSAUPD();
+      arpack->SetMode(2);
+      arpack->SetNumModes(nev);
+      arpack->SetMaxIter(400);
+      arpack->SetTol(1e-8);
+      arpack->SetPrintLevel(2);
+      arpack->SetSolver(*solver);
+
+      eig_solver = arpack;
+   }
+
+   eig_solver->SetOperators(*a, *m);
+
+   // 8. Compute the eigenmodes and extract the array of eigenvalues. Define a
+   //    parallel grid function to represent each of the eigenmodes returned by
+   //    the solver.
+   Array<double> eigenvalues;
+   eig_solver->Solve();
+   eig_solver->GetEigenvalues(eigenvalues);
+
+   cout << endl;
+   std::ios::fmtflags old_fmt = cout.flags();
+   cout.setf(std::ios::scientific);
+   std::streamsize old_prec = cout.precision(14);
+   for (int i=0; i<nev; i++)
+   {
+      cout << "Eigenvalue lambda   " << eigenvalues[i] << endl;
+   }
+   cout.precision(old_prec);
+   cout.flags(old_fmt);
+   cout << endl;
+
+   GridFunction x(fespace);
+
+   // 9. Save the refined mesh and the modes in parallel. This output can be
+   //    viewed later using GLVis: "glvis -np <np> -m mesh -g mode".
+   {
+      ostringstream mesh_name, mode_name;
+      mesh_name << "ex11.mesh";
+
+      ofstream mesh_ofs(mesh_name.str().c_str());
+      mesh_ofs.precision(8);
+      mesh->Print(mesh_ofs);
+
+      for (int i=0; i<nev; i++)
+      {
+         // convert eigenvector from Vector to GridFunction
+         x = eig_solver->GetEigenvector(i);
+
+         mode_name << "mode_" << setfill('0') << setw(2) << i;
+
+         ofstream mode_ofs(mode_name.str().c_str());
+         mode_ofs.precision(8);
+         x.Save(mode_ofs);
+         mode_name.str("");
+      }
+   }
+
+   // 10. Send the solution by socket to a GLVis server.
+   if (visualization)
+   {
+      char vishost[] = "localhost";
+      int  visport   = 19916;
+      socketstream mode_sock(vishost, visport);
+      mode_sock.precision(8);
+
+      for (int i=0; i<nev; i++)
+      {
+         cout << "Eigenmode " << i+1 << '/' << nev
+              << ", Lambda = " << eigenvalues[i] << endl;
+
+         // convert eigenvector from Vector to GridFunction
+         x = eig_solver->GetEigenvector(i);
+
+         mode_sock << "solution\n" << *mesh << x << flush
+                   << "window_title 'Eigenmode " << i+1 << '/' << nev
+                   << ", Lambda = " << eigenvalues[i] << "'" << endl;
+
+         char c;
+         cout << "press (q)uit or (c)ontinue --> " << flush;
+         cin >> c;
+
+         if (c != 'c')
+         {
+            break;
+         }
+      }
+      mode_sock.close();
+   }
+
+   // 11. Free the used memory.
+   delete eig_solver;
+   delete solver;
+   delete m;
+   delete a;
+
+   delete fespace;
+   if (order > 0)
+   {
+      delete fec;
+   }
+   delete mesh;
+
+   return 0;
+}
+
+#endif // MFEM_USE_ARPACK

examples/ex11p.cpp

@@ -72,6 +72,8 @@ int main(int argc, char *argv[])
    int seed = 75;
    bool slu_solver  = false;
    bool sp_solver = false;
+   bool lob_solver = true;
+   bool arp_solver = false;
    bool cpardiso_solver = false;
    bool visualization = 1;
 
@@ -97,6 +99,10 @@ int main(int argc, char *argv[])
    args.AddOption(&sp_solver, "-sp", "--strumpack", "-no-sp",
                   "--no-strumpack", "Use the STRUMPACK Solver.");
 #endif
+#ifdef MFEM_USE_ARPACK
+   args.AddOption(&arp_solver, "-arp", "--arpack", "-no-arp",
+                  "--no-arpack", "Use the Parallel ARPACK Solver.");
+#endif
 #ifdef MFEM_USE_MKL_CPARDISO
    args.AddOption(&cpardiso_solver, "-cpardiso", "--cpardiso", "-no-cpardiso",
                   "--no-cpardiso", "Use the MKL CPardiso Solver.");
@@ -113,6 +119,11 @@ int main(int argc, char *argv[])
               << "         Defaulting to SuperLU." << endl;
       sp_solver = false;
    }
+   if (arp_solver)
+   {
+      lob_solver = false;
+   }
+
    // The command line options are also passed to the STRUMPACK
    // solver. So do not exit if some options are not recognized.
    if (!sp_solver)
@@ -243,70 +254,119 @@ int main(int argc, char *argv[])
    // 8. Define and configure the LOBPCG eigensolver and the BoomerAMG
    //    preconditioner for A to be used within the solver. Set the matrices
    //    which define the generalized eigenproblem A x = lambda M x.
+   Solver * solver = NULL;
    Solver * precond = NULL;
    if (!slu_solver && !sp_solver && !cpardiso_solver)
    {
       HypreBoomerAMG * amg = new HypreBoomerAMG(*A);
       amg->SetPrintLevel(0);
       precond = amg;
-   }
-   else
-   {
-#ifdef MFEM_USE_SUPERLU
-      if (slu_solver)
+
+      if (arp_solver)
+      {
+         HyprePCG * pcg = new HyprePCG(*A);
+         pcg->SetTol(1e-12);
+         pcg->SetPreconditioner(*amg);
+         solver = pcg;
+      }
+   }
+#ifdef MFEM_USE_SUPERLU
+   else if (slu_solver)
+   {
+      SuperLUSolver * superlu = new SuperLUSolver(MPI_COMM_WORLD);
+      superlu->SetPrintStatistics(false);
+      superlu->SetSymmetricPattern(true);
+      superlu->SetColumnPermutation(superlu::PARMETIS);
+      superlu->SetOperator(*Arow);
+
+      if (arp_solver)
+      {
+         solver = superlu;
+      }
+      else
       {
-         SuperLUSolver * superlu = new SuperLUSolver(MPI_COMM_WORLD);
-         superlu->SetPrintStatistics(false);
-         superlu->SetSymmetricPattern(true);
-         superlu->SetColumnPermutation(superlu::PARMETIS);
-         superlu->SetOperator(*Arow);
          precond = superlu;
       }
+   }
 #endif
 #ifdef MFEM_USE_STRUMPACK
-      if (sp_solver)
+   else if (sp_solver)
+   {
+      STRUMPACKSolver * strumpack = new STRUMPACKSolver(argc, argv,
+                                                        MPI_COMM_WORLD);
+      strumpack->SetPrintFactorStatistics(true);
+      strumpack->SetPrintSolveStatistics(false);
+      strumpack->SetKrylovSolver(strumpack::KrylovSolver::DIRECT);
+      strumpack->SetReorderingStrategy(strumpack::ReorderingStrategy::METIS);
+      strumpack->SetMatching(strumpack::MatchingJob::NONE);
+      strumpack->SetCompression(strumpack::CompressionType::NONE);
+      strumpack->SetOperator(*Arow);
+      strumpack->SetFromCommandLine();
+      if (arp_solver)
+      {
+         solver = strumpack;
+      }
+      else
       {
-         STRUMPACKSolver * strumpack = new STRUMPACKSolver(MPI_COMM_WORLD, argc, argv);
-         strumpack->SetPrintFactorStatistics(true);
-         strumpack->SetPrintSolveStatistics(false);
-         strumpack->SetKrylovSolver(strumpack::KrylovSolver::DIRECT);
-         strumpack->SetReorderingStrategy(strumpack::ReorderingStrategy::METIS);
-         strumpack->SetMatching(strumpack::MatchingJob::NONE);
-         strumpack->SetCompression(strumpack::CompressionType::NONE);
-         strumpack->SetOperator(*Arow);
-         strumpack->SetFromCommandLine();
          precond = strumpack;
       }
+   }
 #endif
 #ifdef MFEM_USE_MKL_CPARDISO
-      if (cpardiso_solver)
+   else if (cpardiso_solver)
+   {
+      auto cpardiso = new CPardisoSolver(A->GetComm());
+      cpardiso->SetMatrixType(CPardisoSolver::MatType::REAL_STRUCTURE_SYMMETRIC);
+      cpardiso->SetPrintLevel(1);
+      cpardiso->SetOperator(*A);
+      if (arp_solver)
+      {
+         solver = cpardiso;
+      }
+      else
       {
-         auto cpardiso = new CPardisoSolver(A->GetComm());
-         cpardiso->SetMatrixType(CPardisoSolver::MatType::REAL_STRUCTURE_SYMMETRIC);
-         cpardiso->SetPrintLevel(1);
-         cpardiso->SetOperator(*A);
          precond = cpardiso;
       }
-#endif
    }
+#endif
 
-   HypreLOBPCG * lobpcg = new HypreLOBPCG(MPI_COMM_WORLD);
-   lobpcg->SetNumModes(nev);
-   lobpcg->SetRandomSeed(seed);
-   lobpcg->SetPreconditioner(*precond);
-   lobpcg->SetMaxIter(200);
-   lobpcg->SetTol(1e-8);
-   lobpcg->SetPrecondUsageMode(1);
-   lobpcg->SetPrintLevel(1);
-   lobpcg->SetMassMatrix(*M);
-   lobpcg->SetOperator(*A);
+   SymGenEigensolver * eig_solver = NULL;
+
+   if (lob_solver)
+   {
+      HypreLOBPCG * lobpcg = new HypreLOBPCG(MPI_COMM_WORLD);
+      lobpcg->SetNumModes(nev);
+      lobpcg->SetRandomSeed(seed);
+      lobpcg->SetPreconditioner(*precond);
+      lobpcg->SetMaxIter(200);
+      lobpcg->SetTol(1e-8);
+      lobpcg->SetPrecondUsageMode(1);
+      lobpcg->SetPrintLevel(1);
+
+      eig_solver = lobpcg;
+   }
+#ifdef MFEM_USE_ARPACK
+   else if (arp_solver)
+   {
+      ArPackPSAUPD * arpack = new ArPackPSAUPD(MPI_COMM_WORLD);
+      arpack->SetNumModes(nev);
+      arpack->SetMaxIter(400);
+      arpack->SetTol(1e-8);
+      arpack->SetMode(3);
+      arpack->SetPrintLevel(2);
+      arpack->SetSolver(*solver);
+
+      eig_solver = arpack;
+   }
+#endif
+   eig_solver->SetOperators(*A, *M);
 
    // 9. Compute the eigenmodes and extract the array of eigenvalues. Define a
    //    parallel grid function to represent each of the eigenmodes returned by
    //    the solver.
    Array<real_t> eigenvalues;
-   lobpcg->Solve();
-   lobpcg->GetEigenvalues(eigenvalues);
+   eig_solver->Solve();
+   eig_solver->GetEigenvalues(eigenvalues);
    ParGridFunction x(fespace);
 
    // 10. Save the refined mesh and the modes in parallel. This output can be
@@ -321,8 +381,8 @@ int main(int argc, char *argv[])
 
       for (int i=0; i<nev; i++)
       {
-         // convert eigenvector from HypreParVector to ParGridFunction
-         x = lobpcg->GetEigenvector(i);
+         // convert eigenvector from Vector to ParGridFunction
+         x.Distribute(eig_solver->GetEigenvector(i));
 
          mode_name << "mode_" << setfill('0') << setw(2) << i << "."
                    << setfill('0') << setw(6) << myid;
@@ -350,8 +410,8 @@ int main(int argc, char *argv[])
                  << ", Lambda = " << eigenvalues[i] << endl;
          }
 
-         // convert eigenvector from HypreParVector to ParGridFunction
-         x = lobpcg->GetEigenvector(i);
+         // convert eigenvector from Vector to ParGridFunction
+         x.Distribute(eig_solver->GetEigenvector(i));
 
          mode_sock << "parallel " << num_procs << " " << myid << "\n"
                    << "solution\n" << *pmesh << x << flush
@@ -375,7 +435,8 @@ int main(int argc, char *argv[])
    }
 
    // 12. Free the used memory.
-   delete lobpcg;
+   delete eig_solver;
+   delete solver;
    delete precond;
    delete M;
    delete A;

examples/ex11p_arpack.cpp

@@ -0,0 +1,381 @@
+//                       MFEM Example 11 - Parallel Version
+//
+// Compile with: make ex11p
+//
+// Sample runs:  mpirun -np 4 ex11p -m ../data/square-disc.mesh
+//               mpirun -np 4 ex11p -m ../data/star.mesh
+//               mpirun -np 4 ex11p -m ../data/escher.mesh
+//               mpirun -np 4 ex11p -m ../data/fichera.mesh
+//               mpirun -np 4 ex11p -m ../data/square-disc-p2.vtk -o 2
+//               mpirun -np 4 ex11p -m ../data/square-disc-p3.mesh -o 3
+//               mpirun -np 4 ex11p -m ../data/square-disc-nurbs.mesh -o -1
+//               mpirun -np 4 ex11p -m ../data/disc-nurbs.mesh -o -1 -n 20
+//               mpirun -np 4 ex11p -m ../data/pipe-nurbs.mesh -o -1
+//               mpirun -np 4 ex11p -m ../data/ball-nurbs.mesh -o 2
+//               mpirun -np 4 ex11p -m ../data/star-surf.mesh
+//               mpirun -np 4 ex11p -m ../data/square-disc-surf.mesh
+//               mpirun -np 4 ex11p -m ../data/inline-segment.mesh
+//               mpirun -np 4 ex11p -m ../data/amr-quad.mesh
+//               mpirun -np 4 ex11p -m ../data/amr-hex.mesh
+//               mpirun -np 4 ex11p -m ../data/mobius-strip.mesh -n 8
+//               mpirun -np 4 ex11p -m ../data/klein-bottle.mesh -n 10
+//
+// Description:  This example code demonstrates the use of MFEM to solve the
+//               eigenvalue problem -Delta u = lambda u with homogeneous
+//               Dirichlet boundary conditions.
+//
+//               We compute a number of the lowest eigenmodes by discretizing
+//               the Laplacian and Mass operators using a FE space of the
+//               specified order, or an isoparametric/isogeometric space if
+//               order < 1 (quadratic for quadratic curvilinear mesh, NURBS for
+//               NURBS mesh, etc.)
+//
+//               The example highlights the use of the LOBPCG and ARPACK
+//               eigenvalue solvers together with the BoomerAMG preconditioner
+//               in HYPRE, as well as optionally the SuperLU parallel direct
+//               solver. Reusing a single GLVis visualization window for
+//               multiple eigenfunctions is also illustrated.
+//
+//               We recommend viewing Example 1 before viewing this example.
+
+#include "mfem.hpp"
+#include <fstream>
+#include <iostream>
+
+using namespace std;
+using namespace mfem;
+
+int main(int argc, char *argv[])
+{
+   // 1. Initialize MPI.
+   int num_procs, myid;
+   MPI_Init(&argc, &argv);
+   MPI_Comm_size(MPI_COMM_WORLD, &num_procs);
+   MPI_Comm_rank(MPI_COMM_WORLD, &myid);
+
+   // 2. Parse command-line options.
+   const char *mesh_file = "../data/star.mesh";
+   int ser_ref_levels = 2;
+   int par_ref_levels = 1;
+   int order = 1;
+   int nev = 5;
+   bool slu_solver = false;
+   bool use_arpack = false;
+   bool visualization = 1;
+
+   OptionsParser args(argc, argv);
+   args.AddOption(&mesh_file, "-m", "--mesh",
+                  "Mesh file to use.");
+   args.AddOption(&ser_ref_levels, "-rs", "--refine-serial",
+                  "Number of times to refine the mesh uniformly in serial.");
+   args.AddOption(&par_ref_levels, "-rp", "--refine-parallel",
+                  "Number of times to refine the mesh uniformly in parallel.");
+   args.AddOption(&order, "-o", "--order",
+                  "Finite element order (polynomial degree) or -1 for"
+                  " isoparametric space.");
+   args.AddOption(&nev, "-n", "--num-eigs",
+                  "Number of desired eigenmodes.");
+#ifdef MFEM_USE_SUPERLU
+   args.AddOption(&slu_solver, "-slu", "--superlu", "-no-slu",
+                  "--no-superlu", "Use the SuperLU Solver.");
+#endif
+#ifdef MFEM_USE_ARPACK
+   args.AddOption(&use_arpack, "-arpack", "--use-arpack", "-no-arpack",
+                  "--no-arpack",
+                  "Enable or disable the use of ARPACK.");
+#endif
+   args.AddOption(&visualization, "-vis", "--visualization", "-no-vis",
+                  "--no-visualization",
+                  "Enable or disable GLVis visualization.");
+   args.Parse();
+   if (!args.Good())
+   {
+      if (myid == 0)
+      {
+         args.PrintUsage(cout);
+      }
+      MPI_Finalize();
+      return 1;
+   }
+   if (myid == 0)
+   {
+      args.PrintOptions(cout);
+   }
+
+   // 3. Read the (serial) mesh from the given mesh file on all processors. We
+   //    can handle triangular, quadrilateral, tetrahedral, hexahedral, surface
+   //    and volume meshes with the same code.
+   Mesh *mesh;
+   ifstream imesh(mesh_file);
+   if (!imesh)
+   {
+      if (myid == 0)
+      {
+         cerr << "\nCan not open mesh file: " << mesh_file << '\n' << endl;
+      }
+      MPI_Finalize();
+      return 2;
+   }
+   mesh = new Mesh(imesh, 1, 1);
+   imesh.close();
+   int dim = mesh->Dimension();
+
+   // 4. Refine the serial mesh on all processors to increase the resolution. In
+   //    this example we do 'ref_levels' of uniform refinement (2 by default, or
+   //    specified on the command line with -rs).
+   for (int lev = 0; lev < ser_ref_levels; lev++)
+   {
+      mesh->UniformRefinement();
+   }
+
+   // 5. Define a parallel mesh by a partitioning of the serial mesh. Refine
+   //    this mesh further in parallel to increase the resolution (1 time by
+   //    default, or specified on the command line with -rp). Once the parallel
+   //    mesh is defined, the serial mesh can be deleted.
+   ParMesh *pmesh = new ParMesh(MPI_COMM_WORLD, *mesh);
+   delete mesh;
+   for (int lev = 0; lev < par_ref_levels; lev++)
+   {
+      pmesh->UniformRefinement();
+   }
+
+   // 6. Define a parallel finite element space on the parallel mesh. Here we
+   //    use continuous Lagrange finite elements of the specified order. If
+   //    order < 1, we instead use an isoparametric/isogeometric space.
+   FiniteElementCollection *fec;
+   if (order > 0)
+   {
+      fec = new H1_FECollection(order, dim);
+   }
+   else if (pmesh->GetNodes())
+   {
+      fec = pmesh->GetNodes()->OwnFEC();
+   }
+   else
+   {
+      fec = new H1_FECollection(order = 1, dim);
+   }
+   ParFiniteElementSpace *fespace = new ParFiniteElementSpace(pmesh, fec);
+   HYPRE_Int size = fespace->GlobalTrueVSize();
+   if (myid == 0)
+   {
+      cout << "Number of unknowns: " << size << endl;
+   }
+
+   // 7. Set up the parallel bilinear forms a(.,.) and m(.,.) on the finite
+   //    element space. The first corresponds to the Laplacian operator -Delta,
+   //    while the second is a simple mass matrix needed on the right hand side
+   //    of the generalized eigenvalue problem below. The boundary conditions
+   //    are implemented by elimination with special values on the diagonal to
+   //    shift the Dirichlet eigenvalues out of the computational range. After
+   //    serial and parallel assembly we extract the corresponding parallel
+   //    matrices A and M.
+   ConstantCoefficient one(1.0);
+   Array<int> ess_bdr;
+   if (pmesh->bdr_attributes.Size())
+   {
+      ess_bdr.SetSize(pmesh->bdr_attributes.Max());
+      ess_bdr = 1;
+   }
+
+   ParBilinearForm *a = new ParBilinearForm(fespace);
+   a->AddDomainIntegrator(new DiffusionIntegrator(one));
+   if (pmesh->bdr_attributes.Size() == 0)
+   {
+      // Add a mass term if the mesh has no boundary, e.g. periodic mesh or
+      // closed surface.
+      a->AddDomainIntegrator(new MassIntegrator(one));
+   }
+   a->Assemble();
+   a->EliminateEssentialBCDiag(ess_bdr, 1.0);
+   a->Finalize();
+
+   ParBilinearForm *m = new ParBilinearForm(fespace);
+   m->AddDomainIntegrator(new MassIntegrator(one));
+   m->Assemble();
+   // shift the eigenvalue corresponding to eliminated dofs to a large value
+   m->EliminateEssentialBCDiag(ess_bdr, numeric_limits<double>::min());
+   m->Finalize();
+
+   HypreParMatrix *A = a->ParallelAssemble();
+   HypreParMatrix *M = m->ParallelAssemble();
+
+#ifdef MFEM_USE_SUPERLU
+   Operator * Arow = NULL;
+   if (slu_solver)
+   {
+      Arow = new SuperLURowLocMatrix(*A);
+   }
+#endif
+
+   delete a;
+   delete m;
+
+   // 8. Define and configure the LOBPCG eigensolver and the BoomerAMG
+   //    preconditioner for A to be used within the solver. Set the matrices
+   //    which define the generalized eigenproblem A x = lambda M x.
+   Eigensolver * esolver = NULL;
+   Solver      *  solver = NULL;
+   Solver      * precond = NULL;
+
+   if (!slu_solver)
+   {
+      HypreBoomerAMG * amg = new HypreBoomerAMG(*A);
+      amg->SetPrintLevel(0);
+      precond = amg;
+
+#ifdef MFEM_USE_ARPACK
+      if ( use_arpack )
+      {
+         HyprePCG * pcg = new HyprePCG(*A);
+         pcg->SetTol(1e-12);
+         pcg->SetMaxIter(200);
+         pcg->SetPreconditioner(*amg);
+         pcg->SetPrintLevel(0);
+
+         solver = pcg;
+      }
+#endif
+   }
+#ifdef MFEM_USE_SUPERLU
+   else
+   {
+      SuperLUSolver * superlu = new SuperLUSolver(MPI_COMM_WORLD);
+      superlu->SetPrintStatistics(false);
+      superlu->SetSymmetricPattern(true);
+      superlu->SetColumnPermutation(superlu::PARMETIS);
+      superlu->SetOperator(*Arow);
+
+      solver  = use_arpack?superlu:NULL;
+      precond = use_arpack?NULL:superlu;
+   }
+#endif
+
+   if ( use_arpack )
+   {
+      ParArPackSym * arpack = new ParArPackSym(MPI_COMM_WORLD);
+      arpack->SetMode(3);
+      arpack->SetPrintLevel(2);
+      arpack->SetSolver(*solver);
+
+      esolver = arpack;
+   }
+   else
+   {
+      HypreLOBPCG * lobpcg = new HypreLOBPCG(MPI_COMM_WORLD);
+      lobpcg->SetPreconditioner(*precond);
+      lobpcg->SetPrecondUsageMode(1);
+      lobpcg->SetPrintLevel(1);
+
+      esolver = lobpcg;
+   }
+
+   esolver->SetNumModes(nev);
+   esolver->SetMaxIter(100);
+   esolver->SetTol(1e-8);
+
+   esolver->SetMassMatrix(*M);
+   esolver->SetOperator(*A);
+
+   // 9. Compute the eigenmodes and extract the array of eigenvalues. Define a
+   //    parallel grid function to represent each of the eigenmodes returned by
+   //    the solver.
+   Array<double> eigenvalues;
+   esolver->Solve();
+   esolver->GetEigenvalues(eigenvalues);
+
+   if ( myid == 0 && use_arpack )
+   {
+      cout << endl;
+      for (int i=0; i<eigenvalues.Size(); i++)
+      {
+         cout << "Eigenvalue lambda " << eigenvalues[i] << endl;
+      }
+      cout << endl;
+   }
+
+   ParGridFunction x(fespace);
+
+   // 10. Save the refined mesh and the modes in parallel. This output can be
+   //     viewed later using GLVis: "glvis -np <np> -m mesh -g mode".
+   {
+      ostringstream mesh_name, mode_name;
+      mesh_name << "mesh." << setfill('0') << setw(6) << myid;
+
+      ofstream mesh_ofs(mesh_name.str().c_str());
+      mesh_ofs.precision(8);
+      pmesh->Print(mesh_ofs);
+
+      for (int i=0; i<nev; i++)
+      {
+         // convert eigenvector from HypreParVector to ParGridFunction
+         x.Distribute(esolver->GetEigenvector(i));
+
+         mode_name << "mode_" << setfill('0') << setw(2) << i << "."
+                   << setfill('0') << setw(6) << myid;
+
+         ofstream mode_ofs(mode_name.str().c_str());
+         mode_ofs.precision(8);
+         x.Save(mode_ofs);
+         mode_name.str("");
+      }
+   }
+
+   // 11. Send the solution by socket to a GLVis server.
+   if (visualization)
+   {
+      char vishost[] = "localhost";
+      int  visport   = 19916;
+      socketstream mode_sock(vishost, visport);
+      mode_sock.precision(8);
+
+      for (int i=0; i<nev; i++)
+      {
+         if ( myid == 0 )
+         {
+            cout << "Eigenmode " << i+1 << '/' << nev
+                 << ", Lambda = " << eigenvalues[i] << endl;
+         }
+
+         // convert eigenvector from HypreParVector to ParGridFunction
+         x.Distribute(esolver->GetEigenvector(i));
+
+         mode_sock << "parallel " << num_procs << " " << myid << "\n"
+                   << "solution\n" << *pmesh << x << flush
+                   << "window_title 'Eigenmode " << i+1 << '/' << nev
+                   << ", Lambda = " << eigenvalues[i] << "'" << endl;
+
+         char c;
+         if (myid == 0)
+         {
+            cout << "press (q)uit or (c)ontinue --> " << flush;
+            cin >> c;
+         }
+         MPI_Bcast(&c, 1, MPI_CHAR, 0, MPI_COMM_WORLD);
+
+         if (c != 'c')
+         {
+            break;
+         }
+      }
+      mode_sock.close();
+   }
+
+   // 12. Free the used memory.
+   delete esolver;
+   delete solver;
+   delete precond;
+   delete M;
+   delete A;
+
+   delete fespace;
+   if (order > 0)
+   {
+      delete fec;
+   }
+   delete pmesh;
+
+   MPI_Finalize();
+
+   return 0;
+}

examples/ex12p.cpp

@@ -276,8 +276,8 @@ int main(int argc, char *argv[])
 
       for (int i=0; i<nev; i++)
       {
-         // convert eigenvector from HypreParVector to ParGridFunction
-         x = lobpcg->GetEigenvector(i);
+         // convert eigenvector from Vector to ParGridFunction
+         x.Distribute(lobpcg->GetEigenvector(i));
 
          mode_name << "mode_" << setfill('0') << setw(2) << i << "."
                    << setfill('0') << setw(6) << myid;
@@ -303,7 +303,7 @@ int main(int argc, char *argv[])
       pmesh->Print(adios2output);
       for (int i=0; i<nev; i++)
       {
-         x = lobpcg->GetEigenvector(i);
+         x.Distribute(lobpcg->GetEigenvector(i));
          // x is a temporary that must be saved immediately
          x.Save(adios2output, "mode_" + std::to_string(i));
       }
@@ -326,8 +326,8 @@ int main(int argc, char *argv[])
                  << ", Lambda = " << eigenvalues[i] << endl;
          }
 
-         // convert eigenvector from HypreParVector to ParGridFunction
-         x = lobpcg->GetEigenvector(i);
+         // convert eigenvector from Vector to ParGridFunction
+         x.Distribute(lobpcg->GetEigenvector(i));
 
          mode_sock << "parallel " << num_procs << " " << myid << "\n"
                    << "solution\n" << *pmesh << x << flush

examples/ex13.cpp

@@ -0,0 +1,282 @@
+//                       MFEM Example 13
+//
+// Compile with: make ex3p
+//
+// Sample runs:  ex13 -m ../data/star.mesh -s 5
+//               ex13 -m ../data/square-disc.mesh -o 2 -n 4 // minres fails to conv.
+//               ex13 -m ../data/beam-hex.mesh
+//               ex13 -m ../data/square-disc.mesh -rs 1 -s 26
+//               ex13 -m ../data/square-disc-nurbs.mesh -rs 3 -s 26
+//               ex13 -m ../data/amr-quad.mesh -o 2 // minres fails to conv.
+//               ex13 -m ../data/mobius-strip.mesh -n 8
+//
+// Description:  This example code solves a simple 3D electromagnetic
+//               eigenmode problem corresponding to the second order
+//               Maxwell equation curl curl E = lambda E with boundary
+//               condition E x n = 0. We discretize with Nedelec finite
+//               elements.
+//
+//               The example demonstrates the use of H(curl) finite element
+//               spaces with the curl-curl and the (vector finite element) mass
+//               bilinear form, as well as the use of the ARPACK eigenmode
+//               solver for symmetric matrices using the shift-invert mode.
+//
+
+#include "mfem.hpp"
+#include <fstream>
+#include <iostream>
+
+using namespace std;
+using namespace mfem;
+
+#ifdef MFEM_USE_ARPACK
+
+int main(int argc, char *argv[])
+{
+   // 1. Parse command-line options.
+   const char *mesh_file = "../data/beam-tet.mesh";
+   int order = 1;
+   int nev = 5;
+   int sr = 2;
+   double sigma = 11.0;
+   bool visualization = 1;
+   bool arp_solver = true;
+
+   OptionsParser args(argc, argv);
+   args.AddOption(&mesh_file, "-m", "--mesh",
+                  "Mesh file to use.");
+   args.AddOption(&order, "-o", "--order",
+                  "Finite element order (polynomial degree).");
+   args.AddOption(&nev, "-n", "--num-eigs",
+                  "Number of desired eigenmodes.");
+   args.AddOption(&sr, "-rs", "--refine-serial",
+                  "Number of times to refine the mesh uniformly in serial.");
+   args.AddOption(&sigma, "-s", "--shift",
+                  "Average of the desired eigenvalue range.");
+   args.AddOption(&visualization, "-vis", "--visualization", "-no-vis",
+                  "--no-visualization",
+                  "Enable or disable GLVis visualization.");
+   args.Parse();
+   if (!args.Good())
+   {
+      args.PrintUsage(cout);
+      return 1;
+   }
+   args.PrintOptions(cout);
+
+   // 2. Read the mesh from the given mesh file.  We can handle triangular,
+   //    quadrilateral, tetrahedral, hexahedral, surface and volume meshes
+   //    with the same code.
+   Mesh *mesh;
+   ifstream imesh(mesh_file);
+   if (!imesh)
+   {
+      cerr << "\nCan not open mesh file: " << mesh_file << '\n' << endl;
+      return 2;
+   }
+   mesh = new Mesh(imesh, 1, 1);
+   imesh.close();
+   int dim = mesh->Dimension();
+
+   // 3. Refine the mesh to increase the resolution. In this example we do
+   //    'ref_levels' of uniform refinement.
+   {
+      int ref_levels = sr;
+      for (int l = 0; l < ref_levels; l++)
+      {
+         mesh->UniformRefinement();
+      }
+   }
+
+   // 4. Define a finite element space on the mesh. Here we use the lowest
+   //    order Nedelec finite elements, but we can easily switch
+   //    to higher-order spaces by changing the value of p.
+   FiniteElementCollection *fec = new ND_FECollection(order, dim);
+   FiniteElementSpace *fespace = new FiniteElementSpace(mesh, fec);
+   int size = fespace->GetVSize();
+
+   cout << "Number of unknowns: " << size << endl;
+   cout << "Number of boundary attributes: " << mesh->bdr_attributes.Max()
+        << endl;
+
+   // 5. Set up the parallel bilinear form corresponding to the EM diffusion
+   //    operator curl muinv curl - sigma I, by adding the curl-curl and the
+   //    mass domain integrators and finally imposing homogeneous Dirichlet
+   //    boundary conditions. The boundary conditions are implemented by
+   //    marking all the boundary attributes from the mesh as essential
+   //    (Dirichlet). After serial and parallel assembly we extract the
+   //    parallel matrices A and M.
+   Coefficient *muinv    = new ConstantCoefficient(1.0);
+   Coefficient *negSigma = new ConstantCoefficient(-sigma);
+
+   BilinearForm *a = new BilinearForm(fespace);
+   a->AddDomainIntegrator(new CurlCurlIntegrator(*muinv));
+   a->AddDomainIntegrator(new VectorFEMassIntegrator(*negSigma));
+   a->Assemble();
+   Array<int> ess_bdr(mesh->bdr_attributes.Max());
+   ess_bdr = 1;
+   a->EliminateEssentialBC(ess_bdr);
+   a->Finalize();
+
+   BilinearForm *m = new BilinearForm(fespace);
+   m->AddDomainIntegrator(new VectorFEMassIntegrator());
+   m->Assemble();
+   m->EliminateEssentialBCDiag(ess_bdr, sqrt(numeric_limits<double>::min()));
+   m->Finalize();
+
+   // 6. Define a parallel grid function to approximate each of the
+   // eigenmodes returned by the solver.  Use this as a template to
+   // create a special multi-vector object needed by the eigensolver
+   // which is then initialized with random values.
+   GridFunction x(fespace);
+   x = 0.0;
+
+   // 7. Define and configure the GMRES
+   //    solver to be used within the eigensolver.
+   Solver    * solver = NULL;
+   if ( false )
+   {
+      GMRESSolver *  gmres = new GMRESSolver();
+
+      gmres->SetOperator(*a);
+      gmres->SetRelTol(1e-8);
+      gmres->SetMaxIter(1000);
+      gmres->SetPrintLevel(0);
+      solver = gmres;
+   }
+   else
+   {
+#ifndef MFEM_USE_SUITESPARSE
+      cout << "Building MINRESSolver" << endl;
+      MINRESSolver * minres = new MINRESSolver();
+
+      minres->SetRelTol(1e-12);
+      minres->SetMaxIter(1000);
+      minres->SetPrintLevel(0);
+      solver = minres;
+#else
+      // 7. If MFEM was compiled with SuiteSparse, use UMFPACK to solve the system.
+      cout << "Building UMFPackSolver" << endl;
+      UMFPackSolver * umf_solver = new UMFPackSolver;
+      umf_solver->Control[UMFPACK_ORDERING] = UMFPACK_ORDERING_METIS;
+      solver = umf_solver;
+#endif
+   }
+   solver->SetOperator(a->SpMat());
+
+   // 7. Define and configure the ARPACK eigensolver
+   SymGenEigensolver * eig_solver = NULL;
+   if (arp_solver)
+   {
+      ArPackSAUPD * arpack = new ArPackSAUPD();
+
+      arpack->SetNumModes(nev);
+      arpack->SetMaxIter(400);
+      arpack->SetTol(1e-8);
+      arpack->SetShift(sigma);
+      arpack->SetMode(3);
+      arpack->SetPrintLevel(2);
+      arpack->SetSolver(*solver);
+
+      eig_solver = arpack;
+   }
+
+   eig_solver->SetOperators(*a, *m);
+
+   // Obtain the eigenvalues and eigenvectors
+   Array<double> eigenvalues(nev);
+   eigenvalues = -1.0;
+
+   // arpack->Solve(eigenvalues, *eigenvectors);
+   eig_solver->Solve();
+
+   eig_solver->GetEigenvalues(eigenvalues);
+
+   cout << endl;
+   std::ios::fmtflags old_fmt = cout.flags();
+   cout.setf(std::ios::scientific);
+   std::streamsize old_prec = cout.precision(14);
+   for (int i=0; i<min(nev,eigenvalues.Size()); i++)
+   {
+      cout << "Eigenvalue lambda   " << eigenvalues[i] << endl;
+   }
+   cout.precision(old_prec);
+   cout.flags(old_fmt);
+   cout << endl;
+
+   VisItDataCollection visit_dc("Example13", mesh);
+   GridFunction ** mode = new GridFunction*[min(nev,eigenvalues.Size())];
+   for (int i=0; i<min(nev,eigenvalues.Size()); i++)
+   {
+      mode[i] = new GridFunction(fespace);
+      *mode[i] = eig_solver->GetEigenvector(i);
+
+      ostringstream modeName;
+      modeName << "mode_" << setfill('0') << setw(2) << i;
+      visit_dc.RegisterField(modeName.str().c_str(),mode[i]);
+   }
+   visit_dc.Save();
+
+   // 8. Save the refined mesh and the modes. This output can
+   //    be viewed later using GLVis: "glvis -m mesh -g mode".
+   {
+      ofstream mesh_ofs("refined.mesh");
+      mesh_ofs.precision(8);
+      mesh->Print(mesh_ofs);
+
+      for (int i=0; i<min(nev,eigenvalues.Size()); i++)
+      {
+         x = eig_solver->GetEigenvector(i);
+
+         ostringstream modeName;
+         modeName << "mode_" << setfill('0') << setw(2) << i;
+
+         ofstream mode_ofs(modeName.str().c_str());
+         mode_ofs.precision(8);
+         x.Save(mode_ofs);
+         modeName.str("");
+      }
+   }
+
+   // 9. Send the solution by socket to a GLVis server.
+   if (visualization)
+   {
+      char vishost[] = "localhost";
+      int  visport   = 19916;
+      socketstream mode_sock(vishost, visport);
+      mode_sock.precision(8);
+
+      for (int i=0; i<min(nev,eigenvalues.Size()); i++)
+      {
+         x = eig_solver->GetEigenvector(i);
+
+         mode_sock << "solution\n" << *mesh << x << flush;
+
+         char c;
+         cout << "press (q)uit or (c)ontinue --> " << flush;
+         cin >> c;
+
+         if (c != 'c')
+         {
+            break;
+         }
+      }
+      mode_sock.close();
+   }
+
+   // 10. Free the used memory.
+   delete a;
+   delete m;
+   delete negSigma;
+   delete muinv;
+   delete eig_solver;
+   delete solver;
+   // delete X;
+   delete fespace;
+   delete fec;
+   delete mesh;
+
+   return 0;
+}
+
+#endif // MFEM_USE_ARPACK

examples/ex13p.cpp

@@ -215,8 +215,8 @@ int main(int argc, char *argv[])
 
       for (int i=0; i<nev; i++)
       {
-         // convert eigenvector from HypreParVector to ParGridFunction
-         x = ame->GetEigenvector(i);
+         // convert eigenvector from Vector to ParGridFunction
+         x.Distribute(ame->GetEigenvector(i));
 
          mode_name << "mode_" << setfill('0') << setw(2) << i << "."
                    << setfill('0') << setw(6) << myid;
@@ -244,8 +244,8 @@ int main(int argc, char *argv[])
                  << ", Lambda = " << eigenvalues[i] << endl;
          }
 
-         // convert eigenvector from HypreParVector to ParGridFunction
-         x = ame->GetEigenvector(i);
+         // convert eigenvector from Vector to ParGridFunction
+         x.Distribute(ame->GetEigenvector(i));
 
          mode_sock << "parallel " << num_procs << " " << myid << "\n"
                    << "solution\n" << *pmesh << x << flush

examples/ex32p.cpp

@@ -228,7 +228,7 @@ int main(int argc, char *argv[])
       for (int i=0; i<nev; i++)
       {
          // convert eigenvector from HypreParVector to ParGridFunction
-         x = ame->GetEigenvector(i);
+         x.Distribute(ame->GetEigenvector(i));
          curl.Mult(x, dx);
 
          mode_name << "mode_" << setfill('0') << setw(2) << i << "."
@@ -295,7 +295,7 @@ int main(int argc, char *argv[])
             }
 
             // convert eigenvector from HypreParVector to ParGridFunction
-            x = ame->GetEigenvector(i);
+            x.Distribute(ame->GetEigenvector(i));
             curl.Mult(x, dx);
 
             {
@@ -469,7 +469,7 @@ int main(int argc, char *argv[])
             }
 
             // convert eigenvector from HypreParVector to ParGridFunction
-            x = ame->GetEigenvector(i);
+            x.Distribute(ame->GetEigenvector(i));
             curl.Mult(x, dx);
 
             {
@@ -599,7 +599,7 @@ int main(int argc, char *argv[])
             }
 
             // convert eigenvector from HypreParVector to ParGridFunction
-            x = ame->GetEigenvector(i);
+            x.Distribute(ame->GetEigenvector(i));
             curl.Mult(x, dx);
 
             mode_sock << "parallel " << num_procs << " " << myid << "\n"

examples/ex35p.cpp

@@ -658,7 +658,7 @@ void ScalarWaveGuide(int mode, ParGridFunction &x)
    lobpcg.SetOperator(*A);
    lobpcg.Solve();
 
-   x = lobpcg.GetEigenvector(mode);
+   x.Distribute(lobpcg.GetEigenvector(mode));
 
    delete A;
    delete M;
@@ -714,7 +714,7 @@ void VectorWaveGuide(int mode, ParGridFunction &x)
    ame.SetOperator(*A);
    ame.Solve();
 
-   x = ame.GetEigenvector(mode);
+   x.Distribute(ame.GetEigenvector(mode));
 
    delete A;
    delete M;
@@ -780,7 +780,7 @@ void PseudoScalarWaveGuide(int mode, ParGridFunction &x_l2)
    lobpcg.SetOperator(*A);
    lobpcg.Solve();
 
-   x = lobpcg.GetEigenvector(mode);
+   x.Distribute(lobpcg.GetEigenvector(mode));
 
    x_l2.ProjectCoefficient(xCoef);
 

examples/makefile

@@ -31,6 +31,9 @@ SEQ_DEVICE_EXAMPLES = ex1 ex3 ex4 ex5 ex6 ex9 ex14 ex22 ex24 ex25 ex26 ex34
 PAR_DEVICE_EXAMPLES = ex1p ex2p ex3p ex4p ex5p ex6p ex7p ex9p ex13p ex14p \
    ex22p ex24p ex25p ex26p ex34p ex35p
 
+ifeq ($(MFEM_USE_ARPACK),YES)
+   SEQ_EXAMPLES += ex11 ex13
+endif
 ifeq ($(MFEM_USE_LAPACK),YES)
    SEQ_EXAMPLES += ex38
 endif

linalg/CMakeLists.txt

@@ -23,6 +23,7 @@ list(APPEND SRCS
   complex_operator.cpp
   constraints.cpp
   densemat.cpp
+  eigensolvers.cpp
   filteredsolver.cpp
   handle.cpp
   matrix.cpp
@@ -55,6 +56,7 @@ list(APPEND HDRS
   dinvariants.hpp
   dtensor.hpp
   dual.hpp
+  eigensolvers.hpp
   filteredsolver.hpp
   handle.hpp
   invariants.hpp
@@ -101,6 +103,11 @@ if (MFEM_USE_MPI)
   endif()
 endif()
 
+if (MFEM_USE_ARPACK)
+  list(APPEND SRCS arpack.cpp)
+  list(APPEND HDRS arpack.hpp)
+endif()
+
 if (MFEM_USE_SUNDIALS)
   list(APPEND SRCS sundials.cpp)
   list(APPEND HDRS sundials.hpp)

linalg/arpack.hpp

@@ -0,0 +1,271 @@
+// Copyright (c) 2010-2025, Lawrence Livermore National Security, LLC. Produced
+// at the Lawrence Livermore National Laboratory. All Rights reserved. See files
+// LICENSE and NOTICE for details. LLNL-CODE-806117.
+//
+// This file is part of the MFEM library. For more information and source code
+// availability visit https://mfem.org.
+//
+// MFEM is free software; you can redistribute it and/or modify it under the
+// terms of the BSD-3 license. We welcome feedback and contributions, see file
+// CONTRIBUTING.md for details.
+
+#ifndef MFEM_ARPACK
+#define MFEM_ARPACK
+
+#include "../config/config.hpp"
+
+#ifdef MFEM_USE_ARPACK
+
+#include <string>
+
+#ifdef MFEM_USE_MPI
+#include <mpi.h>
+#include "hypre.hpp"
+#endif
+
+#include "operator.hpp"
+
+#define SSAUPD  ssaupd_
+#define SSEUPD  sseupd_
+#define DSAUPD  dsaupd_
+#define DSEUPD  dseupd_
+
+#ifdef MFEM_USE_MPI
+#define PSSAUPD pssaupd_
+#define PSSEUPD psseupd_
+#define PDSAUPD pdsaupd_
+#define PDSEUPD pdseupd_
+#endif
+
+extern "C" void SSAUPD(int *ido, char *bmat, int *n,
+                       char *which, int *nev, float *tol, float *resid,
+                       int *ncv, float *v, int *ldv,
+                       int *iparam, int *ipntr,
+                       float *workd, float *workl, int *lworkl, int *info);
+
+extern "C" void SSEUPD(int *, char *, int *, float *,
+                       float *, int *, float *, char *, int *, char *,
+                       int *, float *, float *, int *, float *,
+                       int *, int  *, int *, float *,
+                       float *, int *, int *);
+
+extern "C" void DSAUPD(int *ido, char *bmat, int *n,
+                       char *which, int *nev, double *tol, double *resid,
+                       int *ncv, double *v, int *ldv,
+                       int *iparam, int *ipntr,
+                       double *workd, double *workl, int *lworkl, int *info);
+
+extern "C" void DSEUPD(int *, char *, int *, double *,
+                       double *, int *, double *, char *, int *, char *,
+                       int *, double *, double *, int *, double *,
+                       int *, int  *, int *, double *,
+                       double *, int *, int *);
+
+#ifdef MFEM_USE_MPI
+
+extern "C" void PSSAUPD(int *comm, int *ido, char *bmat, int *n,
+                        char *which, int *nev, float *tol, float *resid,
+                        int *ncv, float *v, int *ldv,
+                        int *iparam, int *ipntr,
+                        float *workd, float *workl, int *lworkl, int *info);
+
+extern "C" void PSSEUPD(int *comm, int *, char *, int *, float *,
+                        float *, int *, float *, char *, int *, char *,
+                        int *, float *, float *, int *, float *,
+                        int *, int  *, int *, float *,
+                        float *, int *, int *);
+
+extern "C" void PDSAUPD(int *comm, int *ido, char *bmat, int *n,
+                        char *which, int *nev, double *tol, double *resid,
+                        int *ncv, double *v, int *ldv,
+                        int *iparam, int *ipntr,
+                        double *workd, double *workl, int *lworkl, int *info);
+
+extern "C" void PDSEUPD(int *comm, int *, char *, int *, double *,
+                        double *, int *, double *, char *, int *, char *,
+                        int *, double *, double *, int *, double *,
+                        int *, int  *, int *, double *,
+                        double *, int *, int *);
+
+#endif
+
+extern "C" {
+   void arpackgetcommdbg_(int *,int *,int *);
+   void arpacksetcommdbg_(int *,int *,int *);
+   void arpacksymdbg_(int *,int *,int *,int *,int *,int *,int *);
+   void arpacknonsymdbg_(int *,int *,int *,int *,int *,int *,int *);
+   void arpackcmplxdbg_(int *,int *,int *,int *,int *,int *,int *);
+}
+
+namespace mfem
+{
+
+/// Wrapper for the ARPACK routine SSAUPD or DSAUPD
+class ArPackSAUPD : public SymEigensolver, public SymGenEigensolver
+{
+public:
+
+   ArPackSAUPD();
+   virtual ~ArPackSAUPD();
+
+   /** ARPACK modes are described in section 3.5 of the ARPACK manual.
+       Mode 1: regular mode to solve A x = lambda x
+               No solver and no mass matrix are needed.
+       Mode 2: regular inverse mode to solve A x = lambda M x
+               Both A and M are needed and the solver should compute M^{-1}.
+       Mode 3: shift-invert mode to solve either A x = lambda x
+               or A x = lambda M x
+               Mass matrix is optional.  The solver should compute
+               (A-sigma I)^{-1} or (A-sigma M)^{-1}.  The shift parameter,
+               sigma, also needs to be set with SetShift().
+       Mode 4: Buckling mode to solve K x = lambda K_G x
+               K is set using SetMassMatrix(), K_G is set using SetOperator(),
+          and the solver should compute (K-sigma K_G)^{-1}.  The shift
+               parameter, sigma, also needs to be set with SetShift().
+       Mode 5: Cayley mode to solve A x = lambda M x
+               Both A and M are needed and the solver should compute
+               (A - sigma M)^{-1}.  The shift parameter, sigma, also needs
+               to be set with SetShift().
+    */
+   void SetMode(int mode);
+
+   inline void SetTol(real_t tol) override         {      tol_ = tol;      }
+   inline void SetMaxIter(int max_iter) override   { max_iter_ = max_iter; }
+   inline void SetPrintLevel(int logging) override {  logging_ = logging;  }
+   inline void SetShift(real_t sigma)              {    sigma_ = sigma;    }
+   inline void SetNumModes(int num_eigs) override  {      nev_ = num_eigs; }
+
+   virtual void SetSolver(Solver & solver);
+   virtual void SetOperator(const Operator & A) override;
+   virtual void SetMassMatrix(const Operator & M);
+   virtual void SetOperators(const Operator & A, const Operator & B) override
+   { SetOperator(A); SetMassMatrix(B); }
+
+   void Solve() override;
+
+   virtual int GetNumConverged() const override { return iparam_[4]; }
+
+   /// Collect the converged eigenvalues
+   virtual void GetEigenvalues(Array<real_t> & eigenvalues) const override;
+
+   /// Extract a single eigenvector
+   virtual const Vector & GetEigenvector(unsigned int i) const override;
+
+   /// Transfer ownership of the converged eigenvectors
+   Vector ** StealEigenvectors() override;
+
+protected:
+
+   int myid_;       // Index of this processor
+   int max_iter_;
+   int logging_;
+
+   // The following variables are for ARPACK
+   int nloc_;       // number of items stored locally
+   int nev_;        // number of requested eigenvalues
+   int ncv_;        // number of ritz vectors
+   int rvec_;       // boolean to return eigenvectors as well
+   int mode_;       // 1 = standard, 2 = generalized, 3 = shift invert,
+   // 4 = buckling, 5 = Cayley
+   int lworkl_;     // length of lworkl_ work array
+   int iparam_[12]; // arpack parameters
+   int ipntr_[12];  // arpack pointers
+
+   char bmat_;      // I for standard problem, G for generalized
+   char which_[3];  // spectrum portion: LA, SA, LM, SM, BE
+   char hwmny_;     // DSEUPD: A for all eigenvalues, S for some
+
+   real_t tol_;     // relative accuracy bound for Ritz values
+   real_t sigma_;   // eigenvalue shift parameter
+
+   int    * select_;// workspace used during eigenvalue computation
+   real_t * dv_;    // Ritz values
+   real_t * v_;     // ncv Lanczos basis vectors
+   real_t * resid_; // residual vector
+   real_t * workd_; // work array for 3 vectors used in Arnoldi iteration
+   real_t * workl_; // work array
+
+   // Operators and Vectors needed outside of ARPACK
+   Solver   * solver_;
+   const Operator * A_;
+   const Operator * B_;
+
+   Vector * w_;
+   Vector * x_;
+   Vector * y_;
+   Vector * z_;
+
+   mutable Vector ** eigenvectors_;
+
+   std::string solverName_;
+
+   void reverseComm();
+
+   int reverseCommMode1();
+   int reverseCommMode2();
+   int reverseCommMode3();
+   int reverseCommMode4();
+   int reverseCommMode5();
+
+   virtual void prepareEigenvectors() const;
+
+   void printErrors(const int & info, const int iparam[],
+                    const char & bmat, const int & n,
+                    const char which[],
+                    const int & nev, const int & ncv,
+                    const int & lworkl );
+
+private:
+
+   virtual int computeNlocf() { return nloc_; }
+   virtual int computeIter(int & ido);
+   virtual int computeEigs();
+
+};
+
+#ifdef MFEM_USE_MPI
+
+class ArPackPSAUPD : public ArPackSAUPD
+{
+public:
+   ArPackPSAUPD(MPI_Comm comm);
+   virtual ~ArPackPSAUPD() {}
+
+   void SetOperator(const Operator & A);
+   void SetMassMatrix(const Operator & M);
+
+   /// Collect the converged eigenvalues
+   void GetEigenvalues(Array<real_t> & eigenvalues) const;
+
+   /// Extract a single eigenvector
+   const Vector & GetEigenvector(unsigned int i) const;
+
+   /// Transfer ownership of the converged eigenvectors
+   // HypreParVector ** StealEigenvectors();
+   Vector ** StealEigenvectors();
+
+protected:
+
+   void prepareEigenvectors() const;
+
+private:
+
+   MPI_Comm comm_;
+   MPI_Fint commf_; // Fortran style MPI communicator
+   int numProcs_;   // Number of processors
+
+   mutable HYPRE_Int * part_; // parallel partitioning for eigenvectors
+
+   int computeNlocf();
+   int computeIter(int & ido);
+   int computeEigs();
+
+};
+
+#endif // MFEM_USE_MPI
+
+};
+
+#endif // MFEM_USE_ARPACK
+
+#endif // MFEM_ARPACK

linalg/eigensolvers.cpp

@@ -0,0 +1,20 @@
+// Copyright (c) 2010-2025, Lawrence Livermore National Security, LLC. Produced
+// at the Lawrence Livermore National Laboratory. All Rights reserved. See files
+// LICENSE and NOTICE for details. LLNL-CODE-806117.
+//
+// This file is part of the MFEM library. For more information and source code
+// availability visit https://mfem.org.
+//
+// MFEM is free software; you can redistribute it and/or modify it under the
+// terms of the BSD-3 license. We welcome feedback and contributions, see file
+// CONTRIBUTING.md for details.
+
+#include "linalg.hpp"
+#include "eigensolvers.hpp"
+
+using namespace std;
+
+namespace mfem
+{
+
+};

linalg/eigensolvers.hpp

@@ -0,0 +1,396 @@
+// Copyright (c) 2010-2025, Lawrence Livermore National Security, LLC. Produced
+// at the Lawrence Livermore National Laboratory. All Rights reserved. See files
+// LICENSE and NOTICE for details. LLNL-CODE-806117.
+//
+// This file is part of the MFEM library. For more information and source code
+// availability visit https://mfem.org.
+//
+// MFEM is free software; you can redistribute it and/or modify it under the
+// terms of the BSD-3 license. We welcome feedback and contributions, see file
+// CONTRIBUTING.md for details.
+
+#ifndef MFEM_EIGENSOLVERS
+#define MFEM_EIGENSOLVERS
+
+#include "vector.hpp"
+
+namespace mfem
+{
+
+/// Abstract Eigenequation
+/// Defines the operator of the linear eigenvalue equation
+///    A x_i = lambda_i x_i
+/// Where A is a real-valued operator, the lambda_i are the eigenvalues,
+/// and x_i are the eigenvectors.
+class Eigenequation
+{
+protected:
+   Eigenequation() = default;
+
+public:
+   virtual ~Eigenequation() = default;
+
+   /// @brief Set the operator A of the eigenvalue equation
+   virtual void SetOperator(const Operator & A) = 0;
+};
+
+/// Abstract Complex-valued Eigenequation
+/// Defines the operator of the linear eigenvalue equation
+///    A x_i = lambda_i x_i
+/// Where A is a complex-valued operator, the lambda_i are the eigenvalues,
+/// and x_i are the eigenvectors.
+class ComplexEigenequation
+{
+protected:
+   ComplexEigenequation() = default;
+
+public:
+   virtual ~ComplexEigenequation() = default;
+
+   /// @brief Set the real and imaginary parts of the operator A
+   virtual void SetOperator(const Operator & Ar, const Operator & Ai) = 0;
+};
+
+/// Abstract Generalized Eigenequation
+/// Defines the operator of the linear eigenvalue equation
+///    A x_i = lambda_i B x_i
+/// Where A and B are real-valued operators, the lambda_i are the eigenvalues,
+/// and x_i are the eigenvectors.
+class GenEigenequation
+{
+protected:
+   GenEigenequation() = default;
+
+public:
+   virtual ~GenEigenequation() = default;
+
+   /// @brief Set the operators A and B of the generalized eigenvalue equation
+   virtual void SetOperators(const Operator & A, const Operator & B) = 0;
+};
+
+/// Abstract Complex-valued Generalized Eigenequation
+/// Defines the operator of the linear eigenvalue equation
+///    A x_i = lambda_i B x_i
+/// Where A and B are complex-valued operators, the lambda_i are the
+/// eigenvalues, and x_i are the eigenvectors.
+class ComplexGenEigenequation
+{
+protected:
+   ComplexGenEigenequation() = default;
+
+public:
+   virtual ~ComplexGenEigenequation() = default;
+
+   /// @brief Set the real and imaginary parts of the operators A and B
+   virtual void SetOperators(const Operator & Ar, const Operator & Ai,
+                             const Operator & Br, const Operator & Bi) = 0;
+};
+
+/// Abstract Eigensolver
+/// Computes eigenvalue/eigenvector pairs for the linear system
+///    A x_i = lambda_i x_i
+/// Where the lambda_i are the eigenvalues and x_i are the eigenvectors.
+class EigensolverBase
+{
+protected:
+   EigensolverBase() = default;
+
+public:
+   virtual ~EigensolverBase() = default;
+
+   /// @brief Stopping criteria based on numerical tolerance
+   ///
+   /// @note This may be defined differently by different solvers.
+   virtual void SetTol(real_t tol) = 0;
+
+   /// @brief Stopping criteria based on number of iterations required to
+   /// reach convergence.
+   ///
+   /// @note This may also be defined differently in different solvers.
+   virtual void SetMaxIter(int max_iter) = 0;
+
+   /// @brief Controls the type and amount of information printed to
+   ///        standard output.
+   virtual void SetPrintLevel(int logging) = 0;
+
+   /// @brief Set the number of desired eigenmodes to compute
+   virtual void SetNumModes(int num_eigs) = 0;
+
+   /// @brief Get the number of converged eigenmodes
+   virtual int GetNumConverged() const = 0;
+
+   /// @brief Perform the eigenvalue solve
+   virtual void Solve() = 0;
+};
+
+/// Symmetric Eigensolver
+/// If A^T = A the linear system must have real-valued eigenvalues
+/// and eigenvectors.
+class SymEigensolver : public EigensolverBase, public Eigenequation
+{
+protected:
+   SymEigensolver() = default;
+
+public:
+   virtual ~SymEigensolver() = default;
+
+   /// @brief Collect the converged eigenvalues
+   ///
+   /// The length of the array should equal the number of converged eigenvalues.
+   virtual void GetEigenvalues(Array<real_t> & eigenvalues) const = 0;
+
+   /// @brief Extract a single eigenvector
+   ///
+   /// The index i should be in the range [0, numConverged). The
+   virtual const Vector & GetEigenvector(unsigned int i) const = 0;
+
+   /// @brief Transfer ownership of the converged eigenvectors
+   ///
+   /// The array should contain numConverged vectors.
+   virtual Vector ** StealEigenvectors() = 0;
+};
+
+/// Symmetric Generalized Eigensolver
+/// If A^T = A and M^T = M the linear system must have real-valued eigenvalues
+/// and eigenvectors.
+class SymGenEigensolver : public EigensolverBase, public GenEigenequation
+{
+protected:
+   SymGenEigensolver() = default;
+
+public:
+   virtual ~SymGenEigensolver() = default;
+
+   /// @brief Collect the converged eigenvalues
+   ///
+   /// The length of the array should equal the number of converged eigenvalues.
+   virtual void GetEigenvalues(Array<real_t> & eigenvalues) const = 0;
+
+   /// @brief Extract a single eigenvector
+   ///
+   /// The index i should be in the range [0, numConverged). The
+   virtual const Vector & GetEigenvector(unsigned int i) const = 0;
+
+   /// @brief Transfer ownership of the converged eigenvectors
+   ///
+   /// The array should contain numConverged vectors.
+   virtual Vector ** StealEigenvectors() = 0;
+};
+
+/// Hermetian Eigensolver
+/// If A^H = A the linear system must have real-valued eigenvalues
+/// but may have complex-valued eigenvectors.
+class HermEigensolver : public EigensolverBase, public ComplexEigenequation
+{
+protected:
+   HermEigensolver() = default;
+
+public:
+   virtual ~HermEigensolver() = default;
+
+   /// @brief Collect the converged eigenvalues
+   ///
+   /// The length of the array should equal the number of converged eigenvalues.
+   virtual void GetEigenvalues(Array<real_t> & eigenvalues) const = 0;
+
+   /// @brief Extract a single eigenvector
+   ///
+   /// The index i should be in the range [0, 2*numConverged). The
+   /// vectors corresponding to even indices are the real parts of the
+   /// converged eigenvectors and the odd indices correspond to the
+   /// imaginary parts.
+   virtual const Vector & GetEigenvector(unsigned int i) const = 0;
+
+   /// @brief Transfer ownership of the converged eigenvectors
+   ///
+   /// The array should contain 2*numConverged vectors with the even
+   /// indices corresponding to the real parts of the converged
+   /// eigenvectors and the odd indices corresponding to the imaginary
+   /// parts.
+   virtual Vector ** StealEigenvectors() = 0;
+};
+
+/// Hermetian Generalized Eigensolver
+/// If A^H = A and M^H = M the linear system must have real-valued eigenvalues
+/// but may have complex-valued eigenvectors.
+class HermGenEigensolver :
+   public EigensolverBase, public ComplexGenEigenequation
+{
+protected:
+   HermGenEigensolver() = default;
+
+public:
+   virtual ~HermGenEigensolver() = default;
+
+   /// @brief Collect the converged eigenvalues
+   ///
+   /// The length of the array should equal the number of converged eigenvalues.
+   virtual void GetEigenvalues(Array<real_t> & eigenvalues) const = 0;
+
+   /// @brief Extract a single eigenvector
+   ///
+   /// The index i should be in the range [0, 2*numConverged). The
+   /// vectors corresponding to even indices are the real parts of the
+   /// converged eigenvectors and the odd indices correspond to the
+   /// imaginary parts.
+   virtual const Vector & GetEigenvector(unsigned int i) const = 0;
+
+   /// @brief Transfer ownership of the converged eigenvectors
+   ///
+   /// The array should contain 2*numConverged vectors with the even
+   /// indices corresponding to the real parts of the converged
+   /// eigenvectors and the odd indices corresponding to the imaginary
+   /// parts.
+   virtual Vector ** StealEigenvectors() = 0;
+};
+
+/// Non-Symmetric Eigensolver
+/// For general real-valued operators A the linear system must have
+/// eigenvalues and eigenvectors which form complex conjugate pairs.
+class NonSymEigensolver : public EigensolverBase, public Eigenequation
+{
+protected:
+   NonSymEigensolver() = default;
+
+public:
+   virtual ~NonSymEigensolver() = default;
+
+   /// @brief Collect the converged eigenvalues
+   ///
+   /// The length of the array should be the number of converged
+   /// eigenvalues. The complex-valued eigenvalues can be constructed
+   /// as: lambda_{2*j} = eig[2*j]+i*eig[2*j+1] and
+   /// lambda_{2*j+1} = eig[2*j]-i*eig[2*j+1]
+   /// With j in the range [0, numConverged/2)
+   virtual void GetEigenvalues(Array<real_t> & eig) const = 0;
+
+   /// @brief Extract a single eigenvector
+   ///
+   /// The index i should be in the range [0, numConverged). The
+   /// vectors corresponding to even indices are the real parts of the
+   /// converged eigenvectors and the odd indices correspond to the
+   /// imaginary parts. If needed, the complex conjugate pairs of
+   /// eigenvectors can be constructed in the same manner described
+   /// for the eigenvalues.
+   virtual const Vector & GetEigenvector(unsigned int i) const = 0;
+
+   /// @brief Transfer ownership of the converged eigenvectors
+   ///
+   /// The array should contain numConverged vectors with the even
+   /// indices corresponding to the real parts of the converged
+   /// eigenvectors and the odd indices corresponding to the imaginary
+   /// parts.
+   virtual Vector ** StealEigenvectors() = 0;
+};
+
+/// Non-Symmetric Eigensolver
+/// For general real-valued operators A and M the linear system must have
+/// eigenvalues and eigenvectors which form complex conjugate pairs.
+class NonSymGenEigensolver : public EigensolverBase, public GenEigenequation
+{
+protected:
+   NonSymGenEigensolver() = default;
+
+public:
+   virtual ~NonSymGenEigensolver() = default;
+
+   /// @brief Collect the converged eigenvalues
+   ///
+   /// The length of the array should be the number of converged
+   /// eigenvalues. The complex-valued eigenvalues can be constructed
+   /// as: lambda_{2*j} = eig[2*j]+i*eig[2*j+1] and
+   /// lambda_{2*j+1} = eig[2*j]-i*eig[2*j+1]
+   /// With j in the range [0, numConverged/2)
+   virtual void GetEigenvalues(Array<real_t> & eig) const = 0;
+
+   /// @brief Extract a single eigenvector
+   ///
+   /// The index i should be in the range [0, numConverged). The
+   /// vectors corresponding to even indices are the real parts of the
+   /// converged eigenvectors and the odd indices correspond to the
+   /// imaginary parts. If needed, the complex conjugate pairs of
+   /// eigenvectors can be constructed in the same manner described
+   /// for the eigenvalues.
+   virtual const Vector & GetEigenvector(unsigned int i) const = 0;
+
+   /// @brief Transfer ownership of the converged eigenvectors
+   ///
+   /// The array should contain numConverged vectors with the even
+   /// indices corresponding to the real parts of the converged
+   /// eigenvectors and the odd indices corresponding to the imaginary
+   /// parts.
+   virtual Vector ** StealEigenvectors() = 0;
+};
+
+/// Complex Eigensolver
+/// Can have arbitrary complex-valued eigenvalues and eigenvectors
+class ComplexEigensolver : public EigensolverBase, public ComplexEigenequation
+{
+protected:
+   ComplexEigensolver() = default;
+
+public:
+   virtual ~ComplexEigensolver() = default;
+
+   /// @brief Collect the converged eigenvalues
+   ///
+   /// The length of the array should be twice the number of converged
+   /// eigenvalues. The complex-valued eigenvalues can be constructed
+   /// as: lambda_j = eig[2*j]+i*eig[2*j+1]
+   virtual void GetEigenvalues(Array<real_t> & eig) const = 0;
+
+   /// @brief Extract a single eigenvector
+   ///
+   /// The index i should be in the range [0, 2*numConverged). The
+   /// vectors corresponding to even indices are the real parts of the
+   /// converged eigenvectors and the odd indices correspond to the
+   /// imaginary parts.
+   virtual const Vector & GetEigenvector(unsigned int i) const = 0;
+
+   /// @brief Transfer ownership of the converged eigenvectors
+   ///
+   /// The array should contain 2*numConverged vectors with the even
+   /// indices corresponding to the real parts of the converged
+   /// eigenvectors and the odd indices corresponding to the imaginary
+   /// parts.
+   virtual Vector ** StealEigenvectors() = 0;
+};
+
+/// Complex Generalized Eigensolver
+/// Can have arbitrary complex-valued eigenvalues and eigenvectors
+class ComplexGenEigensolver :
+   public EigensolverBase, public ComplexGenEigenequation
+{
+protected:
+   ComplexGenEigensolver() = default;
+
+public:
+   virtual ~ComplexGenEigensolver() = default;
+
+   /// @brief Collect the converged eigenvalues
+   ///
+   /// The length of the array should be twice the number of converged
+   /// eigenvalues. The complex-valued eigenvalues can be constructed
+   /// as: lambda_j = eig[2*j]+i*eig[2*j+1]
+   virtual void GetEigenvalues(Array<real_t> & eig) const = 0;
+
+   /// @brief Extract a single eigenvector
+   ///
+   /// The index i should be in the range [0, 2*numConverged). The
+   /// vectors corresponding to even indices are the real parts of the
+   /// converged eigenvectors and the odd indices correspond to the
+   /// imaginary parts.
+   virtual const Vector & GetEigenvector(unsigned int i) const = 0;
+
+   /// @brief Transfer ownership of the converged eigenvectors
+   ///
+   /// The array should contain 2*numConverged vectors with the even
+   /// indices corresponding to the real parts of the converged
+   /// eigenvectors and the odd indices corresponding to the imaginary
+   /// parts.
+   virtual Vector ** StealEigenvectors() = 0;
+};
+
+}
+
+#endif

linalg/hypre.cpp

@@ -6556,7 +6556,7 @@ HypreLOBPCG::SetPreconditioner(Solver & precond)
 }
 
 void
-HypreLOBPCG::SetOperator(Operator & A)
+HypreLOBPCG::SetOperator(const Operator & A)
 {
    HYPRE_BigInt locSize = A.Width();
 
@@ -6603,7 +6603,7 @@ HypreLOBPCG::SetOperator(Operator & A)
 }
 
 void
-HypreLOBPCG::SetMassMatrix(Operator & M)
+HypreLOBPCG::SetMassMatrix(const Operator & M)
 {
    matvec_fn.MatvecCreate  = this->OperatorMatvecCreate;
    matvec_fn.Matvec        = this->OperatorMatvec;
@@ -6624,7 +6624,7 @@ HypreLOBPCG::GetEigenvalues(Array<real_t> & eigs) const
    }
 }
 
-const HypreParVector &
+const Vector &
 HypreLOBPCG::GetEigenvector(unsigned int i) const
 {
    return multi_vec->GetVector(i);
@@ -6866,6 +6866,24 @@ HypreAME::SetPreconditioner(HypreSolver & precond)
    ams_precond = &precond;
 }
 
+void
+HypreAME::SetOperators(const Operator & opA, const Operator & opB)
+{
+   const HypreParMatrix * A = dynamic_cast<const HypreParMatrix *>(&opA);
+   if (A == NULL)
+   {
+      mfem_error("HypreAME::SetOperator : first operator not HypreParMatrix!");
+   }
+   SetOperator(*A);
+
+   const HypreParMatrix * B = dynamic_cast<const HypreParMatrix *>(&opB);
+   if (B == NULL)
+   {
+      mfem_error("HypreAME::SetOperator : second operator not HypreParMatrix!");
+   }
+   SetMassMatrix(*B);
+}
+
 void
 HypreAME::SetOperator(const HypreParMatrix & A)
 {
@@ -6924,7 +6942,7 @@ HypreAME::createDummyVectors() const
    }
 }
 
-const HypreParVector &
+const Vector &
 HypreAME::GetEigenvector(unsigned int i) const
 {
    if ( eigenvectors == NULL )
@@ -6935,7 +6953,7 @@ HypreAME::GetEigenvector(unsigned int i) const
    return *eigenvectors[i];
 }
 
-HypreParVector **
+Vector **
 HypreAME::StealEigenvectors()
 {
    if ( eigenvectors == NULL )
@@ -6944,11 +6962,11 @@ HypreAME::StealEigenvectors()
    }
 
    // Set the local pointers to NULL so that they won't be deleted later
-   HypreParVector ** vecs = eigenvectors;
+   Vector ** vecs = (Vector**)eigenvectors;
    eigenvectors = NULL;
    multi_vec = NULL;
 
-   return vecs;
+   return (Vector**)vecs;
 }
 
 }

linalg/hypre.hpp

@@ -18,7 +18,9 @@
 
 #include "../general/globals.hpp"
 #include "sparsemat.hpp"
+#include "eigensolvers.hpp"
 #include "hypre_parcsr.hpp"
+#include "eigensolvers.hpp"
 #include <mpi.h>
 
 // Enable internal hypre timing routines
@@ -2146,7 +2148,7 @@ public:
     A. Knyazev, M. Argentati, I. Lashuk, and E. Ovtchinnikov, SISC, 29(5),
     2224-2239, 2007.
 */
-class HypreLOBPCG
+class HypreLOBPCG : public SymGenEigensolver
 {
 private:
    MPI_Comm comm;
@@ -2236,38 +2238,43 @@ public:
    HypreLOBPCG(MPI_Comm comm);
    ~HypreLOBPCG();
 
-   void SetTol(real_t tol);
+   void SetTol(real_t tol) override;
    // not implemented in HYPRE
    // real_t GetTol() const;
    void SetRelTol(real_t rel_tol);
    // not implemented in HYPRE
    // real_t GetRelTol() const;
-   void SetMaxIter(int max_iter);
+   void SetMaxIter(int max_iter) override;
    // not implemented in HYPRE
    // int GetMaxIter() const;
-   void SetPrintLevel(int logging);
-   void SetNumModes(int num_eigs) { nev = num_eigs; }
+   void SetPrintLevel(int logging) override;
+   void SetNumModes(int num_eigs) override { nev = num_eigs; }
    void SetPrecondUsageMode(int pcg_mode);
    void SetRandomSeed(int s) { seed = s; }
    void SetInitialVectors(int num_vecs, HypreParVector ** vecs);
 
    // The following four methods support general operators
    void SetPreconditioner(Solver & precond);
-   void SetOperator(Operator & A);
-   void SetMassMatrix(Operator & M);
+   void SetOperators(const Operator & A, const Operator & B) override
+   { SetOperator(A); SetMassMatrix(B); }
+   void SetOperator(const Operator & A);
+   void SetMassMatrix(const Operator & M);
    void SetSubSpaceProjector(Operator & proj) { subSpaceProj = &proj; }
 
    /// Solve the eigenproblem
-   void Solve();
+   void Solve() override;
+
+   int GetNumConverged() const override { return nev; }
 
    /// Collect the converged eigenvalues
-   void GetEigenvalues(Array<real_t> & eigenvalues) const;
+   void GetEigenvalues(Array<real_t> & eigenvalues) const override;
 
    /// Extract a single eigenvector
-   const HypreParVector & GetEigenvector(unsigned int i) const;
+   const Vector & GetEigenvector(unsigned int i) const override;
 
    /// Transfer ownership of the converged eigenvectors
-   HypreParVector ** StealEigenvectors() { return multi_vec->StealVectors(); }
+   Vector ** StealEigenvectors() override
+   { return (Vector**)multi_vec->StealVectors(); }
 };
 
 /** AME eigenvalue solver in hypre
@@ -2292,7 +2299,7 @@ public:
     mass matrix but it seems unlikely that this would be useful so it is not the
     default behavior.
 */
-class HypreAME
+class HypreAME : public SymGenEigensolver
 {
 private:
    int myid;
@@ -2321,28 +2328,31 @@ public:
    HypreAME(MPI_Comm comm);
    ~HypreAME();
 
-   void SetTol(real_t tol);
+   void SetTol(real_t tol) override;
    void SetRelTol(real_t rel_tol);
-   void SetMaxIter(int max_iter);
-   void SetPrintLevel(int logging);
-   void SetNumModes(int num_eigs);
+   void SetMaxIter(int max_iter) override;
+   void SetPrintLevel(int logging) override;
+   void SetNumModes(int num_eigs) override;
 
    // The following four methods support operators of type HypreParMatrix.
    void SetPreconditioner(HypreSolver & precond);
+   void SetOperators(const Operator & opA, const Operator & opB) override;
    void SetOperator(const HypreParMatrix & A);
    void SetMassMatrix(const HypreParMatrix & M);
 
    /// Solve the eigenproblem
-   void Solve();
+   void Solve() override;
+
+   int GetNumConverged() const override { return nev; }
 
    /// Collect the converged eigenvalues
-   void GetEigenvalues(Array<real_t> & eigenvalues) const;
+   void GetEigenvalues(Array<real_t> & eigenvalues) const override;
 
    /// Extract a single eigenvector
-   const HypreParVector & GetEigenvector(unsigned int i) const;
+   const Vector & GetEigenvector(unsigned int i) const override;
 
    /// Transfer ownership of the converged eigenvectors
-   HypreParVector ** StealEigenvectors();
+   Vector ** StealEigenvectors() override;
 };
 
 }

linalg/linalg.hpp

@@ -28,6 +28,7 @@
 #include "symmat.hpp"
 #include "ode.hpp"
 #include "solvers.hpp"
+#include "eigensolvers.hpp"
 #include "handle.hpp"
 #include "invariants.hpp"
 #include "constraints.hpp"
@@ -57,6 +58,10 @@
 #include "ginkgo.hpp"
 #endif
 
+#ifdef MFEM_USE_ARPACK
+#include "arpack.hpp"
+#endif
+
 #ifdef MFEM_USE_MKL_PARDISO
 #include "pardiso.hpp"
 #endif

linalg/operator.hpp

@@ -844,6 +844,22 @@ public:
 };
 
 
+/// Zero Operator N: x -> 0.
+class ZeroOperator : public Operator
+{
+public:
+   /// Create an zero operator of size @a n.
+   explicit ZeroOperator(int n) : Operator(n) { }
+
+   /// Operator application
+   void Mult(const Vector &x, Vector &y) const override
+   { y.SetSize(width); y = 0_r; }
+
+   /// Application of the transpose
+   void MultTranspose(const Vector &x, Vector &y) const override
+   { y.SetSize(width); y = 0_r; }
+};
+
 /// Identity Operator I: x -> x.
 class IdentityOperator : public Operator
 {

makefile

@@ -302,7 +302,7 @@ endif
 MFEM_REQ_LIB_DEPS = SUPERLU MUMPS METIS FMS CONDUIT SIDRE LAPACK SUNDIALS\
  SUITESPARSE STRUMPACK GINKGO GNUTLS HDF5 NETCDF SLEPC PETSC MPFR PUMI HIOP\
  GSLIB OCCA CEED RAJA UMPIRE MKL_CPARDISO MKL_PARDISO AMGX MAGMA CALIPER PARELAG\
- TRIBOL BENCHMARK MOONOLITH ALGOIM
+ TRIBOL BENCHMARK MOONOLITH ALGOIM ARPACK
 
 
 PETSC_ERROR_MSG = $(if $(PETSC_FOUND),,. PETSC config not found: $(PETSC_VARS))
@@ -371,7 +371,8 @@ MFEM_DEFINES = MFEM_VERSION MFEM_VERSION_STRING MFEM_GIT_STRING MFEM_USE_MPI\
  MFEM_USE_SIMD MFEM_USE_ADIOS2 MFEM_USE_MKL_CPARDISO MFEM_USE_MKL_PARDISO MFEM_USE_AMGX\
  MFEM_USE_MAGMA MFEM_USE_MUMPS MFEM_USE_ADFORWARD MFEM_USE_CODIPACK MFEM_USE_CALIPER\
  MFEM_USE_BENCHMARK MFEM_USE_PARELAG MFEM_USE_TRIBOL MFEM_USE_ALGOIM MFEM_USE_ENZYME\
- MFEM_SOURCE_DIR MFEM_INSTALL_DIR MFEM_SHARED_BUILD MFEM_USE_DOUBLE MFEM_USE_SINGLE
+ MFEM_SOURCE_DIR MFEM_INSTALL_DIR MFEM_SHARED_BUILD MFEM_USE_DOUBLE MFEM_USE_SINGLE\
+MFEM_USE_ARPACK
 
 # List of makefile variables that will be written to config.mk:
 MFEM_CONFIG_VARS = MFEM_CXX MFEM_HOST_CXX MFEM_CPPFLAGS MFEM_CXXFLAGS\
@@ -733,6 +734,7 @@ status info:
 	$(info MFEM_TIMER_TYPE        = $(MFEM_TIMER_TYPE))
 	$(info MFEM_USE_SUNDIALS      = $(MFEM_USE_SUNDIALS))
 	$(info MFEM_USE_SUITESPARSE   = $(MFEM_USE_SUITESPARSE))
+	$(info MFEM_USE_ARPACK        = $(MFEM_USE_ARPACK))
 	$(info MFEM_USE_SUPERLU       = $(MFEM_USE_SUPERLU))
 	$(info MFEM_USE_SUPERLU5      = $(MFEM_USE_SUPERLU5))
 	$(info MFEM_USE_MUMPS         = $(MFEM_USE_MUMPS))

miniapps/nurbs/nurbs_ex11p.cpp

@@ -329,8 +329,8 @@ int main(int argc, char *argv[])
 
       for (int i=0; i<nev; i++)
       {
-         // convert eigenvector from HypreParVector to ParGridFunction
-         x = lobpcg->GetEigenvector(i);
+         // convert eigenvector from Vector to ParGridFunction
+         x.Distribute(lobpcg->GetEigenvector(i));
 
          mode_name << "mode_" << setfill('0') << setw(2) << i << "."
                    << setfill('0') << setw(6) << myid;
@@ -357,8 +357,8 @@ int main(int argc, char *argv[])
                  << ", Lambda = " << eigenvalues[i] << endl;
          }
 
-         // convert eigenvector from HypreParVector to ParGridFunction
-         x = lobpcg->GetEigenvector(i);
+         // convert eigenvector from Vector to ParGridFunction
+         x.Distribute(lobpcg->GetEigenvector(i));
 
          mode_sock << "parallel " << num_procs << " " << myid << "\n"
                    << "solution\n" << *pmesh << x << flush