gslib.cpp

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// Copyright (c) 2010-2023, 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 "gslib.hpp"

#ifdef MFEM_USE_GSLIB

// Ignore warnings from the gslib header (GCC version)
#ifdef MFEM_HAVE_GCC_PRAGMA_DIAGNOSTIC
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wunused-function"
#endif

// External GSLIB header (the MFEM header is gslib.hpp)
namespace gslib
{
#include "gslib.h"
}

#ifdef MFEM_HAVE_GCC_PRAGMA_DIAGNOSTIC
#pragma GCC diagnostic pop
#endif

namespace mfem
{

FindPointsGSLIB::FindPointsGSLIB()
   : mesh(NULL),
     fec_map_lin(NULL),
     fdata2D(NULL), fdata3D(NULL), cr(NULL), gsl_comm(NULL),
     dim(-1), points_cnt(0), setupflag(false), default_interp_value(0),
     avgtype(AvgType::ARITHMETIC), bdr_tol(1e-8)
{
   mesh_split.SetSize(4);
   ir_split.SetSize(4);
   fes_rst_map.SetSize(4);
   gf_rst_map.SetSize(4);
   for (int i = 0; i < mesh_split.Size(); i++)
   {
      mesh_split[i] = NULL;
      ir_split[i] = NULL;
      fes_rst_map[i] = NULL;
      gf_rst_map[i] = NULL;
   }

   gsl_comm = new gslib::comm;
   cr       = new gslib::crystal;
#ifdef MFEM_USE_MPI
   int initialized;
   MPI_Initialized(&initialized);
   if (!initialized) { MPI_Init(NULL, NULL); }
   MPI_Comm comm = MPI_COMM_WORLD;
   comm_init(gsl_comm, comm);
#else
   comm_init(gsl_comm, 0);
#endif
}

FindPointsGSLIB::~FindPointsGSLIB()
{
   delete gsl_comm;
   delete cr;
   for (int i = 0; i < 4; i++)
   {
      if (mesh_split[i]) { delete mesh_split[i]; mesh_split[i] = NULL; }
      if (ir_split[i]) { delete ir_split[i]; ir_split[i] = NULL; }
      if (fes_rst_map[i]) { delete fes_rst_map[i]; fes_rst_map[i] = NULL; }
      if (gf_rst_map[i]) { delete gf_rst_map[i]; gf_rst_map[i] = NULL; }
   }
   if (fec_map_lin) { delete fec_map_lin; fec_map_lin = NULL; }
}

#ifdef MFEM_USE_MPI
FindPointsGSLIB::FindPointsGSLIB(MPI_Comm comm_)
   : mesh(NULL),
     fec_map_lin(NULL),
     fdata2D(NULL), fdata3D(NULL), cr(NULL), gsl_comm(NULL),
     dim(-1), points_cnt(0), setupflag(false), default_interp_value(0),
     avgtype(AvgType::ARITHMETIC), bdr_tol(1e-8)
{
   mesh_split.SetSize(4);
   ir_split.SetSize(4);
   fes_rst_map.SetSize(4);
   gf_rst_map.SetSize(4);
   for (int i = 0; i < mesh_split.Size(); i++)
   {
      mesh_split[i] = NULL;
      ir_split[i] = NULL;
      fes_rst_map[i] = NULL;
      gf_rst_map[i] = NULL;
   }

   gsl_comm = new gslib::comm;
   cr      = new gslib::crystal;
   comm_init(gsl_comm, comm_);
}
#endif

void FindPointsGSLIB::Setup(Mesh &m, const double bb_t, const double newt_tol,
                            const int npt_max)
{
   MFEM_VERIFY(m.GetNodes() != NULL, "Mesh nodes are required.");
   MFEM_VERIFY(!(m.GetNodes()->FESpace()->IsVariableOrder()),
               "Variable order mesh is not currently supported.");

   // call FreeData if FindPointsGSLIB::Setup has been called already
   if (setupflag) { FreeData(); }

   crystal_init(cr, gsl_comm);
   mesh = &m;
   dim  = mesh->Dimension();
   const FiniteElement *fe = mesh->GetNodalFESpace()->GetFE(0);
   unsigned dof1D = fe->GetOrder() + 1;

   SetupSplitMeshes();
   if (dim == 2)
   {
      if (ir_split[0]) { delete ir_split[0]; ir_split[0] = NULL; }
      ir_split[0] = new IntegrationRule(3*pow(dof1D, dim));
      SetupIntegrationRuleForSplitMesh(mesh_split[0], ir_split[0], fe->GetOrder());
   }
   else if (dim == 3)
   {

      if (ir_split[1]) { delete ir_split[1]; ir_split[1] = NULL; }
      ir_split[1] = new IntegrationRule(4*pow(dof1D, dim));
      SetupIntegrationRuleForSplitMesh(mesh_split[1], ir_split[1], fe->GetOrder());

      if (ir_split[2]) { delete ir_split[2]; ir_split[2] = NULL; }
      ir_split[2] = new IntegrationRule(3*pow(dof1D, dim));
      SetupIntegrationRuleForSplitMesh(mesh_split[2], ir_split[2], fe->GetOrder());

      if (ir_split[3]) { delete ir_split[3]; ir_split[3] = NULL; }
      ir_split[3] = new IntegrationRule(8*pow(dof1D, dim));
      SetupIntegrationRuleForSplitMesh(mesh_split[3], ir_split[3], fe->GetOrder());
   }

   GetNodalValues(mesh->GetNodes(), gsl_mesh);

   const int pts_cnt = gsl_mesh.Size()/dim,
             NEtot = pts_cnt/(int)pow(dof1D, dim);

   if (dim == 2)
   {
      unsigned nr[2] = { dof1D, dof1D };
      unsigned mr[2] = { 2*dof1D, 2*dof1D };
      double * const elx[2] = { &gsl_mesh(0), &gsl_mesh(pts_cnt) };
      fdata2D = findpts_setup_2(gsl_comm, elx, nr, NEtot, mr, bb_t,
                                pts_cnt, pts_cnt, npt_max, newt_tol);
   }
   else
   {
      unsigned nr[3] = { dof1D, dof1D, dof1D };
      unsigned mr[3] = { 2*dof1D, 2*dof1D, 2*dof1D };
      double * const elx[3] =
      { &gsl_mesh(0), &gsl_mesh(pts_cnt), &gsl_mesh(2*pts_cnt) };
      fdata3D = findpts_setup_3(gsl_comm, elx, nr, NEtot, mr, bb_t,
                                pts_cnt, pts_cnt, npt_max, newt_tol);
   }
   setupflag = true;
}

void FindPointsGSLIB::FindPoints(const Vector &point_pos,
                                 int point_pos_ordering)
{
   MFEM_VERIFY(setupflag, "Use FindPointsGSLIB::Setup before finding points.");
   points_cnt = point_pos.Size() / dim;
   gsl_code.SetSize(points_cnt);
   gsl_proc.SetSize(points_cnt);
   gsl_elem.SetSize(points_cnt);
   gsl_ref.SetSize(points_cnt * dim);
   gsl_dist.SetSize(points_cnt);

   auto xvFill = [&](const double *xv_base[], unsigned xv_stride[], int dim)
   {
      for (int d = 0; d < dim; d++)
      {
         if (point_pos_ordering == Ordering::byNODES)
         {
            xv_base[d] = point_pos.GetData() + d*points_cnt;
            xv_stride[d] = sizeof(double);
         }
         else
         {
            xv_base[d] = point_pos.GetData() + d;
            xv_stride[d] = dim*sizeof(double);
         }
      }
   };
   if (dim == 2)
   {
      const double *xv_base[2];
      unsigned xv_stride[2];
      xvFill(xv_base, xv_stride, dim);
      findpts_2(gsl_code.GetData(), sizeof(unsigned int),
                gsl_proc.GetData(), sizeof(unsigned int),
                gsl_elem.GetData(), sizeof(unsigned int),
                gsl_ref.GetData(),  sizeof(double) * dim,
                gsl_dist.GetData(), sizeof(double),
                xv_base, xv_stride, points_cnt, fdata2D);
   }
   else  // dim == 3
   {
      const double *xv_base[3];
      unsigned xv_stride[3];
      xvFill(xv_base, xv_stride, dim);
      findpts_3(gsl_code.GetData(), sizeof(unsigned int),
                gsl_proc.GetData(), sizeof(unsigned int),
                gsl_elem.GetData(), sizeof(unsigned int),
                gsl_ref.GetData(),  sizeof(double) * dim,
                gsl_dist.GetData(), sizeof(double),
                xv_base, xv_stride, points_cnt, fdata3D);
   }

   // Set the element number and reference position to 0 for points not found
   for (int i = 0; i < points_cnt; i++)
   {
      if (gsl_code[i] == 2 ||
          (gsl_code[i] == 1 && gsl_dist(i) > bdr_tol))
      {
         gsl_elem[i] = 0;
         for (int d = 0; d < dim; d++) { gsl_ref(i*dim + d) = -1.; }
         gsl_code[i] = 2;
      }
   }

   // Map element number for simplices, and ref_pos from [-1,1] to [0,1] for
   // both simplices and quads.
   MapRefPosAndElemIndices();
}

void FindPointsGSLIB::FindPoints(Mesh &m, const Vector &point_pos,
                                 int point_pos_ordering, const double bb_t,
                                 const double newt_tol, const int npt_max)
{
   if (!setupflag || (mesh != &m) )
   {
      Setup(m, bb_t, newt_tol, npt_max);
   }
   FindPoints(point_pos, point_pos_ordering);
}

void FindPointsGSLIB::Interpolate(const Vector &point_pos,
                                  const GridFunction &field_in, Vector &field_out,
                                  int point_pos_ordering)
{
   FindPoints(point_pos, point_pos_ordering);
   Interpolate(field_in, field_out);
}

void FindPointsGSLIB::Interpolate(Mesh &m, const Vector &point_pos,
                                  const GridFunction &field_in, Vector &field_out,
                                  int point_pos_ordering)
{
   FindPoints(m, point_pos, point_pos_ordering);
   Interpolate(field_in, field_out);
}

void FindPointsGSLIB::FreeData()
{
   if (!setupflag) { return; }
   crystal_free(cr);
   if (dim == 2)
   {
      findpts_free_2(fdata2D);
   }
   else
   {
      findpts_free_3(fdata3D);
   }
   gsl_code.DeleteAll();
   gsl_proc.DeleteAll();
   gsl_elem.DeleteAll();
   gsl_mesh.Destroy();
   gsl_ref.Destroy();
   gsl_dist.Destroy();
   for (int i = 0; i < 4; i++)
   {
      if (mesh_split[i]) { delete mesh_split[i]; mesh_split[i] = NULL; }
      if (ir_split[i]) { delete ir_split[i]; ir_split[i] = NULL; }
      if (fes_rst_map[i]) { delete fes_rst_map[i]; fes_rst_map[i] = NULL; }
      if (gf_rst_map[i]) { delete gf_rst_map[i]; gf_rst_map[i] = NULL; }
   }
   if (fec_map_lin) { delete fec_map_lin; fec_map_lin = NULL; }
   setupflag = false;
}

void FindPointsGSLIB::SetupSplitMeshes()
{
   fec_map_lin = new H1_FECollection(1, dim);
   if (mesh->Dimension() == 2)
   {
      int Nvert = 7;
      int NEsplit = 3;
      mesh_split[0] = new Mesh(2, Nvert, NEsplit, 0, 2);

      const double quad_v[7][2] =
      {
         {0, 0}, {0.5, 0}, {1, 0}, {0, 0.5},
         {1./3., 1./3.}, {0.5, 0.5}, {0, 1}
      };
      const int quad_e[3][4] =
      {
         {0, 1, 4, 3}, {1, 2, 5, 4}, {3, 4, 5, 6}
      };

      for (int j = 0; j < Nvert; j++)
      {
         mesh_split[0]->AddVertex(quad_v[j]);
      }
      for (int j = 0; j < NEsplit; j++)
      {
         int attribute = j + 1;
         mesh_split[0]->AddQuad(quad_e[j], attribute);
      }
      mesh_split[0]->FinalizeQuadMesh(1, 1, true);

      fes_rst_map[0] = new FiniteElementSpace(mesh_split[0], fec_map_lin, dim);
      gf_rst_map[0] = new GridFunction(fes_rst_map[0]);
      const int npt = gf_rst_map[0]->Size()/dim;
      for (int k = 0; k < dim; k++)
      {
         for (int j = 0; j < npt; j++)
         {
            (*gf_rst_map[0])(j+k*npt) = quad_v[j][k];
         }
      }
   }
   else if (mesh->Dimension() == 3)
   {
      // Tetrahedron
      {
         int Nvert = 15;
         int NEsplit = 4;
         mesh_split[1] = new Mesh(3, Nvert, NEsplit, 0, 3);

         const double hex_v[15][3] =
         {
            {0, 0, 0.}, {1, 0., 0.}, {0., 1., 0.}, {0, 0., 1.},
            {0.5, 0., 0.}, {0.5, 0.5, 0.}, {0., 0.5, 0.},
            {0., 0., 0.5}, {0.5, 0., 0.5}, {0., 0.5, 0.5},
            {1./3., 0., 1./3.}, {1./3., 1./3., 1./3.}, {0, 1./3., 1./3.},
            {1./3., 1./3., 0}, {0.25, 0.25, 0.25}
         };
         const int hex_e[4][8] =
         {
            {7, 10, 4, 0, 12, 14, 13, 6},
            {10, 8, 1, 4, 14, 11, 5, 13},
            {14, 11, 5, 13, 12, 9, 2, 6},
            {7, 3, 8, 10, 12, 9, 11, 14}
         };

         for (int j = 0; j < Nvert; j++)
         {
            mesh_split[1]->AddVertex(hex_v[j]);
         }
         for (int j = 0; j < NEsplit; j++)
         {
            int attribute = j + 1;
            mesh_split[1]->AddHex(hex_e[j], attribute);
         }
         mesh_split[1]->FinalizeHexMesh(1, 1, true);

         fes_rst_map[1] = new FiniteElementSpace(mesh_split[1], fec_map_lin, dim);
         gf_rst_map[1] = new GridFunction(fes_rst_map[1]);
         const int npt = gf_rst_map[1]->Size()/dim;
         for (int k = 0; k < dim; k++)
         {
            for (int j = 0; j < npt; j++)
            {
               (*gf_rst_map[1])(j+k*npt) = hex_v[j][k];
            }
         }
      }
      // Prism
      {
         int Nvert = 14;
         int NEsplit = 3;
         mesh_split[2] = new Mesh(3, Nvert, NEsplit, 0, 3);

         const double hex_v[14][3] =
         {
            {0, 0, 0}, {0.5, 0, 0}, {1, 0, 0}, {0, 0.5, 0},
            {1./3., 1./3., 0}, {0.5, 0.5, 0}, {0, 1, 0},
            {0, 0, 1}, {0.5, 0, 1}, {1, 0, 1}, {0, 0.5, 1},
            {1./3., 1./3., 1}, {0.5, 0.5, 1}, {0, 1, 1}
         };
         const int hex_e[3][8] =
         {
            {0, 1, 4, 3, 7, 8, 11, 10},
            {1, 2, 5, 4, 8, 9, 12, 11},
            {3, 4, 5, 6, 10, 11, 12, 13}
         };

         for (int j = 0; j < Nvert; j++)
         {
            mesh_split[2]->AddVertex(hex_v[j]);
         }
         for (int j = 0; j < NEsplit; j++)
         {
            int attribute = j + 1;
            mesh_split[2]->AddHex(hex_e[j], attribute);
         }
         mesh_split[2]->FinalizeHexMesh(1, 1, true);

         fes_rst_map[2] = new FiniteElementSpace(mesh_split[2], fec_map_lin, dim);
         gf_rst_map[2] = new GridFunction(fes_rst_map[2]);
         const int npt = gf_rst_map[2]->Size()/dim;
         for (int k = 0; k < dim; k++)
         {
            for (int j = 0; j < npt; j++)
            {
               (*gf_rst_map[2])(j+k*npt) = hex_v[j][k];
            }
         }
      }
      // Pyramid
      {
         int Nvert = 23;
         int NEsplit = 8;
         mesh_split[3] = new Mesh(3, Nvert, NEsplit, 0, 3);

         const double hex_v[23][3] =
         {
            {0.0000, 0.0000, 0.0000}, {0.5000, 0.0000, 0.0000},
            {0.0000, 0.0000, 0.5000}, {0.3333, 0.0000, 0.3333},
            {0.0000, 0.5000, 0.0000}, {0.3333, 0.3333, 0.0000},
            {0.0000, 0.3333, 0.3333}, {0.2500, 0.2500, 0.2500},
            {1.0000, 0.0000, 0.0000}, {0.5000, 0.0000, 0.5000},
            {0.5000, 0.5000, 0.0000}, {0.3333, 0.3333, 0.3333},
            {0.0000, 1.0000, 0.0000}, {0.0000, 0.5000, 0.5000},
            {0.0000, 0.0000, 1.0000}, {1.0000, 0.5000, 0.0000},
            {0.6667, 0.3333, 0.3333}, {0.6667, 0.6667, 0.0000},
            {0.5000, 0.5000, 0.2500}, {1.0000, 1.0000, 0.0000},
            {0.5000, 0.5000, 0.5000}, {0.5000, 1.0000, 0.0000},
            {0.3333, 0.6667, 0.3333}
         };
         const int hex_e[8][8] =
         {
            {2, 3, 1, 0, 6, 7, 5, 4}, {3, 9, 8, 1, 7, 11, 10, 5},
            {7, 11, 10, 5, 6, 13, 12, 4}, {2, 14, 9, 3, 6, 13, 11, 7},
            {9, 16, 15, 8, 11, 18, 17, 10}, {16, 20, 19, 15, 18, 22, 21, 17},
            {18, 22, 21, 17, 11, 13, 12, 10}, {9, 14, 20, 16, 11, 13, 22, 18}
         };

         for (int j = 0; j < Nvert; j++)
         {
            mesh_split[3]->AddVertex(hex_v[j]);
         }
         for (int j = 0; j < NEsplit; j++)
         {
            int attribute = j + 1;
            mesh_split[3]->AddHex(hex_e[j], attribute);
         }
         mesh_split[3]->FinalizeHexMesh(1, 1, true);

         fes_rst_map[3] = new FiniteElementSpace(mesh_split[3], fec_map_lin, dim);
         gf_rst_map[3] = new GridFunction(fes_rst_map[3]);
         const int npt = gf_rst_map[3]->Size()/dim;
         for (int k = 0; k < dim; k++)
         {
            for (int j = 0; j < npt; j++)
            {
               (*gf_rst_map[3])(j+k*npt) = hex_v[j][k];
            }
         }
      }
   }

   NE_split_total = 0;
   split_element_map.SetSize(0);
   split_element_index.SetSize(0);
   int NEsplit = 0;
   for (int e = 0; e < mesh->GetNE(); e++)
   {
      const Geometry::Type gt   = mesh->GetElement(e)->GetGeometryType();
      if (gt == Geometry::TRIANGLE || gt == Geometry::PRISM)
      {
         NEsplit = 3;
      }
      else if (gt == Geometry::TETRAHEDRON)
      {
         NEsplit = 4;
      }
      else if (gt == Geometry::PYRAMID)
      {
         NEsplit = 8;
      }
      else if (gt == Geometry::SQUARE || gt == Geometry::CUBE)
      {
         NEsplit = 1;
      }
      else
      {
         MFEM_ABORT("Unsupported geometry type.");
      }
      NE_split_total += NEsplit;
      for (int i = 0; i < NEsplit; i++)
      {
         split_element_map.Append(e);
         split_element_index.Append(i);
      }
   }
}

void FindPointsGSLIB::SetupIntegrationRuleForSplitMesh(Mesh *meshin,
                                                       IntegrationRule *irule,
                                                       int order)
{
   H1_FECollection fec(order, dim);
   FiniteElementSpace nodal_fes(meshin, &fec, dim);
   meshin->SetNodalFESpace(&nodal_fes);
   const int NEsplit = meshin->GetNE();

   const int dof_cnt = nodal_fes.GetFE(0)->GetDof(),
             pts_cnt = NEsplit * dof_cnt;
   Vector irlist(dim * pts_cnt);

   const TensorBasisElement *tbe =
      dynamic_cast<const TensorBasisElement *>(nodal_fes.GetFE(0));
   MFEM_VERIFY(tbe != NULL, "TensorBasis FiniteElement expected.");
   const Array<int> &dof_map = tbe->GetDofMap();

   DenseMatrix pos(dof_cnt, dim);
   Vector posV(pos.Data(), dof_cnt * dim);
   Array<int> xdofs(dof_cnt * dim);

   // Create an IntegrationRule on the nodes of the reference submesh.
   MFEM_ASSERT(irule->GetNPoints() == pts_cnt, "IntegrationRule does not have"
               "the correct number of points.");
   GridFunction *nodesplit = meshin->GetNodes();
   int pt_id = 0;
   for (int i = 0; i < NEsplit; i++)
   {
      nodal_fes.GetElementVDofs(i, xdofs);
      nodesplit->GetSubVector(xdofs, posV);
      for (int j = 0; j < dof_cnt; j++)
      {
         for (int d = 0; d < dim; d++)
         {
            irlist(pts_cnt * d + pt_id) = pos(dof_map[j], d);
         }
         irule->IntPoint(pt_id).x = irlist(pt_id);
         irule->IntPoint(pt_id).y = irlist(pts_cnt + pt_id);
         if (dim == 3)
         {
            irule->IntPoint(pt_id).z = irlist(2*pts_cnt + pt_id);
         }
         pt_id++;
      }
   }
}

void FindPointsGSLIB::GetNodalValues(const GridFunction *gf_in,
                                     Vector &node_vals)
{
   const GridFunction *nodes     = gf_in;
   const FiniteElementSpace *fes = nodes->FESpace();
   const int NE                  = mesh->GetNE();
   const int vdim                = gf_in->FESpace()->GetVDim();

   IntegrationRule *ir_split_temp = NULL;

   const int dof_1D =  nodes->FESpace()->GetFE(0)->GetOrder()+1;
   const int pts_el = std::pow(dof_1D, dim);
   const int pts_cnt = NE_split_total * pts_el;
   node_vals.SetSize(vdim * pts_cnt);
   node_vals = 0.0;

   int gsl_mesh_pt_index = 0;

   for (int e = 0; e < NE; e++)
   {
      const FiniteElement *fe   = nodes->FESpace()->GetFE(e);
      const Geometry::Type gt   = fe->GetGeomType();
      bool el_to_split = true;
      if (gt == Geometry::TRIANGLE)
      {
         ir_split_temp = ir_split[0];
      }
      else if (gt == Geometry::TETRAHEDRON)
      {
         ir_split_temp = ir_split[1];
      }
      else if (gt == Geometry::PRISM)
      {
         ir_split_temp = ir_split[2];
      }
      else if (gt == Geometry::PYRAMID)
      {
         ir_split_temp = ir_split[3];
      }
      else if (gt == Geometry::SQUARE || gt == Geometry::CUBE)
      {
         el_to_split = false;
      }
      else
      {
         MFEM_ABORT("Unsupported geometry type.");
      }

      if (el_to_split) // Triangle/Tet/Prism
      {
         // Fill gsl_mesh with location of split points.
         Vector locval(vdim);
         for (int i = 0; i < ir_split_temp->GetNPoints(); i++)
         {
            const IntegrationPoint &ip = ir_split_temp->IntPoint(i);
            nodes->GetVectorValue(e, ip, locval);
            for (int d = 0; d < vdim; d++)
            {
               node_vals(pts_cnt*d + gsl_mesh_pt_index) = locval(d);
            }
            gsl_mesh_pt_index++;
         }
      }
      else // Quad/Hex
      {
         const int dof_cnt_split = fe->GetDof();

         const TensorBasisElement *tbe =
            dynamic_cast<const TensorBasisElement *>(fes->GetFE(e));
         MFEM_VERIFY(tbe != NULL, "TensorBasis FiniteElement expected.");
         Array<int> dof_map(dof_cnt_split);
         const Array<int> &dm = tbe->GetDofMap();
         if (dm.Size() > 0) { dof_map = dm; }
         else { for (int i = 0; i < dof_cnt_split; i++) { dof_map[i] = i; } }

         DenseMatrix pos(dof_cnt_split, vdim);
         Vector posV(pos.Data(), dof_cnt_split * vdim);
         Array<int> xdofs(dof_cnt_split * vdim);

         fes->GetElementVDofs(e, xdofs);
         nodes->GetSubVector(xdofs, posV);
         for (int j = 0; j < dof_cnt_split; j++)
         {
            for (int d = 0; d < vdim; d++)
            {
               node_vals(pts_cnt * d + gsl_mesh_pt_index) = pos(dof_map[j], d);
            }
            gsl_mesh_pt_index++;
         }
      }
   }
}


void FindPointsGSLIB::MapRefPosAndElemIndices()
{
   gsl_mfem_ref = gsl_ref;
   gsl_mfem_elem = gsl_elem;

   gsl_mfem_ref -= -1.;  // map  [-1, 1] to
   gsl_mfem_ref *= 0.5;  //      [0,  1]

   int nptorig = points_cnt,
       npt = points_cnt;

   GridFunction *gf_rst_map_temp = NULL;
   int nptsend = 0;

   for (int index = 0; index < npt; index++)
   {
      if (gsl_code[index] != 2 && gsl_proc[index] != gsl_comm->id)
      {
         nptsend +=1;
      }
   }

   // Pack data to send via crystal router
   struct gslib::array *outpt = new gslib::array;
   struct out_pt { double r[3]; uint index, el, proc; };
   struct out_pt *pt;
   array_init(struct out_pt, outpt, nptsend);
   outpt->n=nptsend;
   pt = (struct out_pt *)outpt->ptr;
   for (int index = 0; index < npt; index++)
   {
      if (gsl_code[index] == 2 || gsl_proc[index] == gsl_comm->id)
      {
         continue;
      }
      for (int d = 0; d < dim; ++d)
      {
         pt->r[d]= gsl_mfem_ref(index*dim + d);
      }
      pt->index = index;
      pt->proc  = gsl_proc[index];
      pt->el    = gsl_elem[index];
      ++pt;
   }

   // Transfer data to target MPI ranks
   sarray_transfer(struct out_pt, outpt, proc, 1, cr);

   // Map received points
   npt = outpt->n;
   pt = (struct out_pt *)outpt->ptr;
   for (int index = 0; index < npt; index++)
   {
      IntegrationPoint ip;
      ip.Set3(&pt->r[0]);
      const int elem = pt->el;
      const int mesh_elem = split_element_map[elem];
      const FiniteElement *fe = mesh->GetNodalFESpace()->GetFE(mesh_elem);
      const Geometry::Type gt = fe->GetGeomType();
      pt->el = mesh_elem;

      if (gt == Geometry::SQUARE || gt == Geometry::CUBE) { ++pt; continue; }
      else if (gt == Geometry::TRIANGLE)
      {
         gf_rst_map_temp = gf_rst_map[0];
      }
      else if (gt == Geometry::TETRAHEDRON)
      {
         gf_rst_map_temp = gf_rst_map[1];
      }
      else if (gt == Geometry::PRISM)
      {
         gf_rst_map_temp = gf_rst_map[2];
      }
      else if (gt == Geometry::PYRAMID)
      {
         gf_rst_map_temp = gf_rst_map[3];
      }

      int local_elem = split_element_index[elem];
      Vector mfem_ref(dim);
      // map to rst of macro element
      gf_rst_map_temp->GetVectorValue(local_elem, ip, mfem_ref);

      for (int d = 0; d < dim; d++)
      {
         pt->r[d] = mfem_ref(d);
      }
      ++pt;
   }

   // Transfer data back to source MPI rank
   sarray_transfer(struct out_pt, outpt, proc, 1, cr);
   npt = outpt->n;

   // First copy mapped information for points on other procs
   pt = (struct out_pt *)outpt->ptr;
   for (int index = 0; index < npt; index++)
   {
      gsl_mfem_elem[pt->index] = pt->el;
      for (int d = 0; d < dim; d++)
      {
         gsl_mfem_ref(d + pt->index*dim) = pt->r[d];
      }
      ++pt;
   }
   array_free(outpt);
   delete outpt;

   // Now map information for points on the same proc
   for (int index = 0; index < nptorig; index++)
   {
      if (gsl_code[index] != 2 && gsl_proc[index] == gsl_comm->id)
      {
         const int elem = gsl_elem[index];
         const int mesh_elem = split_element_map[elem];
         const FiniteElement *fe = mesh->GetNodalFESpace()->GetFE(mesh_elem);
         const Geometry::Type gt = fe->GetGeomType();
         gsl_mfem_elem[index] = mesh_elem;
         if (gt == Geometry::SQUARE || gt == Geometry::CUBE) { continue; }
         else if (gt == Geometry::TRIANGLE)
         {
            gf_rst_map_temp = gf_rst_map[0];
         }
         else if (gt == Geometry::TETRAHEDRON)
         {
            gf_rst_map_temp = gf_rst_map[1];
         }
         else if (gt == Geometry::PRISM)
         {
            gf_rst_map_temp = gf_rst_map[2];
         }
         else if (gt == Geometry::PYRAMID)
         {
            gf_rst_map_temp = gf_rst_map[3];
         }

         int local_elem = split_element_index[elem];
         IntegrationPoint ip;
         Vector mfem_ref(gsl_mfem_ref.GetData()+index*dim, dim);
         ip.Set2(mfem_ref.GetData());
         if (dim == 3) { ip.z = mfem_ref(2); }
         gf_rst_map_temp->GetVectorValue(local_elem, ip, mfem_ref);
      }
   }
}

void FindPointsGSLIB::Interpolate(const GridFunction &field_in,
                                  Vector &field_out)
{
   const int  gf_order   = field_in.FESpace()->GetFE(0)->GetOrder(),
              mesh_order = mesh->GetNodalFESpace()->GetFE(0)->GetOrder();

   const FiniteElementCollection *fec_in =  field_in.FESpace()->FEColl();
   const H1_FECollection *fec_h1 = dynamic_cast<const H1_FECollection *>(fec_in);
   const L2_FECollection *fec_l2 = dynamic_cast<const L2_FECollection *>(fec_in);

   if (fec_h1 && gf_order == mesh_order &&
       fec_h1->GetBasisType() == BasisType::GaussLobatto &&
       !field_in.FESpace()->IsVariableOrder())
   {
      InterpolateH1(field_in, field_out);
      return;
   }
   else
   {
      InterpolateGeneral(field_in, field_out);
      if (!fec_l2 || avgtype == AvgType::NONE) { return; }
   }

   // For points on element borders, project the L2 GridFunction to H1 and
   // re-interpolate.
   if (fec_l2)
   {
      Array<int> indl2;
      for (int i = 0; i < points_cnt; i++)
      {
         if (gsl_code[i] == 1) { indl2.Append(i); }
      }
      int borderPts = indl2.Size();
#ifdef MFEM_USE_MPI
      MPI_Allreduce(MPI_IN_PLACE, &borderPts, 1, MPI_INT, MPI_SUM, gsl_comm->c);
#endif
      if (borderPts == 0) { return; } // no points on element borders

      Vector field_out_l2(field_out.Size());
      VectorGridFunctionCoefficient field_in_dg(&field_in);
      int gf_order_h1 = std::max(gf_order, 1); // H1 should be at least order 1
      H1_FECollection fec(gf_order_h1, dim);
      const int ncomp = field_in.FESpace()->GetVDim();
      FiniteElementSpace fes(mesh, &fec, ncomp);
      GridFunction field_in_h1(&fes);

      if (avgtype == AvgType::ARITHMETIC)
      {
         field_in_h1.ProjectDiscCoefficient(field_in_dg, GridFunction::ARITHMETIC);
      }
      else if (avgtype == AvgType::HARMONIC)
      {
         field_in_h1.ProjectDiscCoefficient(field_in_dg, GridFunction::HARMONIC);
      }
      else
      {
         MFEM_ABORT("Invalid averaging type.");
      }

      if (gf_order_h1 == mesh_order) // basis is GaussLobatto by default
      {
         InterpolateH1(field_in_h1, field_out_l2);
      }
      else
      {
         InterpolateGeneral(field_in_h1, field_out_l2);
      }

      // Copy interpolated values for the points on element border
      for (int j = 0; j < ncomp; j++)
      {
         for (int i = 0; i < indl2.Size(); i++)
         {
            int idx = field_in.FESpace()->GetOrdering() == Ordering::byNODES ?
                      indl2[i] + j*points_cnt:
                      indl2[i]*ncomp + j;
            field_out(idx) = field_out_l2(idx);
         }
      }
   }
}

void FindPointsGSLIB::InterpolateH1(const GridFunction &field_in,
                                    Vector &field_out)
{
   FiniteElementSpace ind_fes(mesh, field_in.FESpace()->FEColl());
   GridFunction field_in_scalar(&ind_fes);
   Vector node_vals;

   const int ncomp      = field_in.FESpace()->GetVDim(),
             points_fld = field_in.Size() / ncomp,
             points_cnt = gsl_code.Size();

   field_out.SetSize(points_cnt*ncomp);
   field_out = default_interp_value;

   for (int i = 0; i < ncomp; i++)
   {
      const int dataptrin  = i*points_fld,
                dataptrout = i*points_cnt;
      if (field_in.FESpace()->GetOrdering() == Ordering::byNODES)
      {
         field_in_scalar.NewDataAndSize(field_in.GetData()+dataptrin, points_fld);
      }
      else
      {
         for (int j = 0; j < points_fld; j++)
         {
            field_in_scalar(j) = field_in(i + j*ncomp);
         }
      }
      GetNodalValues(&field_in_scalar, node_vals);

      if (dim==2)
      {
         findpts_eval_2(field_out.GetData()+dataptrout, sizeof(double),
                        gsl_code.GetData(),       sizeof(unsigned int),
                        gsl_proc.GetData(),    sizeof(unsigned int),
                        gsl_elem.GetData(),    sizeof(unsigned int),
                        gsl_ref.GetData(),     sizeof(double) * dim,
                        points_cnt, node_vals.GetData(), fdata2D);
      }
      else
      {
         findpts_eval_3(field_out.GetData()+dataptrout, sizeof(double),
                        gsl_code.GetData(),       sizeof(unsigned int),
                        gsl_proc.GetData(),    sizeof(unsigned int),
                        gsl_elem.GetData(),    sizeof(unsigned int),
                        gsl_ref.GetData(),     sizeof(double) * dim,
                        points_cnt, node_vals.GetData(), fdata3D);
      }
   }
   if (field_in.FESpace()->GetOrdering() == Ordering::byVDIM)
   {
      Vector field_out_temp = field_out;
      for (int i = 0; i < ncomp; i++)
      {
         for (int j = 0; j < points_cnt; j++)
         {
            field_out(i + j*ncomp) = field_out_temp(j + i*points_cnt);
         }
      }
   }
}

void FindPointsGSLIB::InterpolateGeneral(const GridFunction &field_in,
                                         Vector &field_out)
{
   int ncomp   = field_in.VectorDim(),
       nptorig = points_cnt,
       npt     = points_cnt;

   field_out.SetSize(points_cnt*ncomp);
   field_out = default_interp_value;

   if (gsl_comm->np == 1) // serial
   {
      for (int index = 0; index < npt; index++)
      {
         if (gsl_code[index] == 2) { continue; }
         IntegrationPoint ip;
         ip.Set2(gsl_mfem_ref.GetData()+index*dim);
         if (dim == 3) { ip.z = gsl_mfem_ref(index*dim + 2); }
         Vector localval(ncomp);
         field_in.GetVectorValue(gsl_mfem_elem[index], ip, localval);
         if (field_in.FESpace()->GetOrdering() == Ordering::byNODES)
         {
            for (int i = 0; i < ncomp; i++)
            {
               field_out(index + i*npt) = localval(i);
            }
         }
         else //byVDIM
         {
            for (int i = 0; i < ncomp; i++)
            {
               field_out(index*ncomp + i) = localval(i);
            }
         }
      }
   }
   else // parallel
   {
      // Determine number of points to be sent
      int nptsend = 0;
      for (int index = 0; index < npt; index++)
      {
         if (gsl_code[index] != 2) { nptsend +=1; }
      }

      // Pack data to send via crystal router
      struct gslib::array *outpt = new gslib::array;
      struct out_pt { double r[3], ival; uint index, el, proc; };
      struct out_pt *pt;
      array_init(struct out_pt, outpt, nptsend);
      outpt->n=nptsend;
      pt = (struct out_pt *)outpt->ptr;
      for (int index = 0; index < npt; index++)
      {
         if (gsl_code[index] == 2) { continue; }
         for (int d = 0; d < dim; ++d) { pt->r[d]= gsl_mfem_ref(index*dim + d); }
         pt->index = index;
         pt->proc  = gsl_proc[index];
         pt->el    = gsl_mfem_elem[index];
         ++pt;
      }

      // Transfer data to target MPI ranks
      sarray_transfer(struct out_pt, outpt, proc, 1, cr);

      if (ncomp == 1)
      {
         // Interpolate the grid function
         npt = outpt->n;
         pt = (struct out_pt *)outpt->ptr;
         for (int index = 0; index < npt; index++)
         {
            IntegrationPoint ip;
            ip.Set3(&pt->r[0]);
            pt->ival = field_in.GetValue(pt->el, ip, 1);
            ++pt;
         }

         // Transfer data back to source MPI rank
         sarray_transfer(struct out_pt, outpt, proc, 1, cr);
         npt = outpt->n;
         pt = (struct out_pt *)outpt->ptr;
         for (int index = 0; index < npt; index++)
         {
            field_out(pt->index) = pt->ival;
            ++pt;
         }
         array_free(outpt);
         delete outpt;
      }
      else // ncomp > 1
      {
         // Interpolate data and store in a Vector
         npt = outpt->n;
         pt = (struct out_pt *)outpt->ptr;
         Vector vec_int_vals(npt*ncomp);
         for (int index = 0; index < npt; index++)
         {
            IntegrationPoint ip;
            ip.Set3(&pt->r[0]);
            Vector localval(vec_int_vals.GetData()+index*ncomp, ncomp);
            field_in.GetVectorValue(pt->el, ip, localval);
            ++pt;
         }

         // Save index and proc data in a struct
         struct gslib::array *savpt = new gslib::array;
         struct sav_pt { uint index, proc; };
         struct sav_pt *spt;
         array_init(struct sav_pt, savpt, npt);
         savpt->n=npt;
         spt = (struct sav_pt *)savpt->ptr;
         pt  = (struct out_pt *)outpt->ptr;
         for (int index = 0; index < npt; index++)
         {
            spt->index = pt->index;
            spt->proc  = pt->proc;
            ++pt; ++spt;
         }

         array_free(outpt);
         delete outpt;

         // Copy data from save struct to send struct and send component wise
         struct gslib::array *sendpt = new gslib::array;
         struct send_pt { double ival; uint index, proc; };
         struct send_pt *sdpt;
         for (int j = 0; j < ncomp; j++)
         {
            array_init(struct send_pt, sendpt, npt);
            sendpt->n=npt;
            spt  = (struct sav_pt *)savpt->ptr;
            sdpt = (struct send_pt *)sendpt->ptr;
            for (int index = 0; index < npt; index++)
            {
               sdpt->index = spt->index;
               sdpt->proc  = spt->proc;
               sdpt->ival  = vec_int_vals(j + index*ncomp);
               ++sdpt; ++spt;
            }

            sarray_transfer(struct send_pt, sendpt, proc, 1, cr);
            sdpt = (struct send_pt *)sendpt->ptr;
            for (int index = 0; index < static_cast<int>(sendpt->n); index++)
            {
               int idx = field_in.FESpace()->GetOrdering() == Ordering::byNODES ?
                         sdpt->index + j*nptorig :
                         sdpt->index*ncomp + j;
               field_out(idx) = sdpt->ival;
               ++sdpt;
            }
            array_free(sendpt);
         }
         array_free(savpt);
         delete sendpt;
         delete savpt;
      } // ncomp > 1
   } // parallel
}

void OversetFindPointsGSLIB::Setup(Mesh &m, const int meshid,
                                   GridFunction *gfmax,
                                   const double bb_t, const double newt_tol,
                                   const int npt_max)
{
   MFEM_VERIFY(m.GetNodes() != NULL, "Mesh nodes are required.");
   MFEM_VERIFY(!(m.GetNodes()->FESpace()->IsVariableOrder()),
               "Variable order mesh is not currently supported.");

   // FreeData if OversetFindPointsGSLIB::Setup has been called already
   if (setupflag) { FreeData(); }

   crystal_init(cr, gsl_comm);
   mesh = &m;
   dim  = mesh->Dimension();
   const FiniteElement *fe = mesh->GetNodalFESpace()->GetFE(0);
   unsigned dof1D = fe->GetOrder() + 1;

   SetupSplitMeshes();
   if (dim == 2)
   {
      if (ir_split[0]) { delete ir_split[0]; ir_split[0] = NULL; }
      ir_split[0] = new IntegrationRule(3*pow(dof1D, dim));
      SetupIntegrationRuleForSplitMesh(mesh_split[0], ir_split[0], fe->GetOrder());
   }
   else if (dim == 3)
   {
      if (ir_split[1]) { delete ir_split[1]; ir_split[1] = NULL; }
      ir_split[1] = new IntegrationRule(4*pow(dof1D, dim));
      SetupIntegrationRuleForSplitMesh(mesh_split[1], ir_split[1], fe->GetOrder());

      if (ir_split[2]) { delete ir_split[2]; ir_split[2] = NULL; }
      ir_split[2] = new IntegrationRule(3*pow(dof1D, dim));
      SetupIntegrationRuleForSplitMesh(mesh_split[2], ir_split[2], fe->GetOrder());

      if (ir_split[3]) { delete ir_split[3]; ir_split[3] = NULL; }
      ir_split[3] = new IntegrationRule(8*pow(dof1D, dim));
      SetupIntegrationRuleForSplitMesh(mesh_split[3], ir_split[3], fe->GetOrder());
   }

   GetNodalValues(mesh->GetNodes(), gsl_mesh);

   MFEM_ASSERT(meshid>=0, " The ID should be greater than or equal to 0.");

   const int pts_cnt = gsl_mesh.Size()/dim,
             NEtot = pts_cnt/(int)pow(dof1D, dim);

   distfint.SetSize(pts_cnt);
   if (!gfmax)
   {
      distfint = 0.0;
   }
   else
   {
      GetNodalValues(gfmax, distfint);
   }
   u_meshid = (unsigned int)meshid;

   if (dim == 2)
   {
      unsigned nr[2] = { dof1D, dof1D };
      unsigned mr[2] = { 2*dof1D, 2*dof1D };
      double * const elx[2] = { &gsl_mesh(0), &gsl_mesh(pts_cnt) };
      fdata2D = findptsms_setup_2(gsl_comm, elx, nr, NEtot, mr, bb_t,
                                  pts_cnt, pts_cnt, npt_max, newt_tol,
                                  &u_meshid, &distfint(0));
   }
   else
   {
      unsigned nr[3] = { dof1D, dof1D, dof1D };
      unsigned mr[3] = { 2*dof1D, 2*dof1D, 2*dof1D };
      double * const elx[3] =
      { &gsl_mesh(0), &gsl_mesh(pts_cnt), &gsl_mesh(2*pts_cnt) };
      fdata3D = findptsms_setup_3(gsl_comm, elx, nr, NEtot, mr, bb_t,
                                  pts_cnt, pts_cnt, npt_max, newt_tol,
                                  &u_meshid, &distfint(0));
   }
   setupflag = true;
   overset   = true;
}

void OversetFindPointsGSLIB::FindPoints(const Vector &point_pos,
                                        Array<unsigned int> &point_id,
                                        int point_pos_ordering)
{
   MFEM_VERIFY(setupflag, "Use OversetFindPointsGSLIB::Setup before "
               "finding points.");
   MFEM_VERIFY(overset, " Please setup FindPoints for overlapping grids.");
   points_cnt = point_pos.Size() / dim;
   unsigned int match = 0; // Don't find points in the mesh if point_id = mesh_id

   gsl_code.SetSize(points_cnt);
   gsl_proc.SetSize(points_cnt);
   gsl_elem.SetSize(points_cnt);
   gsl_ref.SetSize(points_cnt * dim);
   gsl_dist.SetSize(points_cnt);

   auto xvFill = [&](const double *xv_base[], unsigned xv_stride[], int dim)
   {
      for (int d = 0; d < dim; d++)
      {
         if (point_pos_ordering == Ordering::byNODES)
         {
            xv_base[d] = point_pos.GetData() + d*points_cnt;
            xv_stride[d] = sizeof(double);
         }
         else
         {
            xv_base[d] = point_pos.GetData() + d;
            xv_stride[d] = dim*sizeof(double);
         }
      }
   };
   if (dim == 2)
   {
      const double *xv_base[2];
      unsigned xv_stride[2];
      xvFill(xv_base, xv_stride, dim);
      findptsms_2(gsl_code.GetData(), sizeof(unsigned int),
                  gsl_proc.GetData(), sizeof(unsigned int),
                  gsl_elem.GetData(), sizeof(unsigned int),
                  gsl_ref.GetData(),  sizeof(double) * dim,
                  gsl_dist.GetData(), sizeof(double),
                  xv_base,            xv_stride,
                  point_id.GetData(), sizeof(unsigned int), &match,
                  points_cnt, fdata2D);
   }
   else  // dim == 3
   {
      const double *xv_base[3];
      unsigned xv_stride[3];
      xvFill(xv_base, xv_stride, dim);
      findptsms_3(gsl_code.GetData(), sizeof(unsigned int),
                  gsl_proc.GetData(), sizeof(unsigned int),
                  gsl_elem.GetData(), sizeof(unsigned int),
                  gsl_ref.GetData(),  sizeof(double) * dim,
                  gsl_dist.GetData(), sizeof(double),
                  xv_base,            xv_stride,
                  point_id.GetData(), sizeof(unsigned int), &match,
                  points_cnt, fdata3D);
   }

   // Set the element number and reference position to 0 for points not found
   for (int i = 0; i < points_cnt; i++)
   {
      if (gsl_code[i] == 2 ||
          (gsl_code[i] == 1 && gsl_dist(i) > bdr_tol))
      {
         gsl_elem[i] = 0;
         for (int d = 0; d < dim; d++) { gsl_ref(i*dim + d) = -1.; }
         gsl_code[i] = 2;
      }
   }

   // Map element number for simplices, and ref_pos from [-1,1] to [0,1] for both
   // simplices and quads.
   MapRefPosAndElemIndices();
}

void OversetFindPointsGSLIB::Interpolate(const Vector &point_pos,
                                         Array<unsigned int> &point_id,
                                         const GridFunction &field_in,
                                         Vector &field_out,
                                         int point_pos_ordering)
{
   FindPoints(point_pos, point_id, point_pos_ordering);
   Interpolate(field_in, field_out);
}


} // namespace mfem

#endif // MFEM_USE_GSLIB