EpetraExt_MMHelpers.cpp

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// ***********************************************************************
//
//     EpetraExt: Epetra Extended - Linear Algebra Services Package
//                 Copyright (2011) Sandia Corporation
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#include <EpetraExt_ConfigDefs.h>
#include <EpetraExt_MMHelpers.h>
#include <Epetra_Comm.h>
#include <Epetra_CrsMatrix.h>
#include <Epetra_Import.h>
#include <Epetra_Distributor.h>
#include <Epetra_HashTable.h>
#include <Epetra_Util.h>
#include <Epetra_Import_Util.h>
#include <Epetra_GIDTypeSerialDenseVector.h>

#include <Teuchos_TimeMonitor.hpp>
#include <limits>

#ifdef HAVE_MPI
#include "Epetra_MpiComm.h"
#include "Epetra_MpiDistributor.h"
#endif
#define MIN(x,y)    ((x)<(y)?(x):(y))
#define MIN3(x,y,z) ((x)<(y)?(MIN(x,z)):(MIN(y,z)))

namespace EpetraExt {

//------------------------------------
// DEBUGGING ROUTINES
void debug_print_distor(const char * label, const Epetra_Distributor * Distor, const Epetra_Comm & Comm) {
#ifdef HAVE_MPI
  const Epetra_MpiDistributor * MDistor = dynamic_cast<const Epetra_MpiDistributor*>(Distor);
  printf("[%d] %s\n",Comm.MyPID(),label);
  printf("[%d] NumSends = %d NumRecvs = %d\n",Comm.MyPID(),MDistor->NumSends(),MDistor->NumReceives());
  printf("[%d] ProcsTo = ",Comm.MyPID());
  for(int ii=0; ii<MDistor->NumSends(); ii++)
    printf("%d ",MDistor->ProcsTo()[ii]);
  printf("\n[%d] ProcsFrom = ",Comm.MyPID());
  for(int ii=0; ii<MDistor->NumReceives(); ii++)
    printf("%d ",MDistor->ProcsFrom()[ii]);
  printf("\n");
  fflush(stdout);
#endif
}

//------------------------------------
// DEBUGGING ROUTINES
void debug_compare_import(const Epetra_Import * Import1,const Epetra_Import * Import2) {
  if(!Import1 && !Import2) return;
  const Epetra_Comm & Comm = (Import1)? Import1->SourceMap().Comm() : Import2->SourceMap().Comm();
  bool flag=true;
  int PID=Comm.MyPID();
  if( (!Import1 && Import2) || (Import2 && !Import1) ) {printf("[%d] DCI: One Import exists, the other does not\n",PID);return;}
  if(!Import1->SourceMap().SameAs(Import2->SourceMap())) {printf("[%d] DCI: SourceMaps don't match\n",PID);return;}
  if(!Import1->TargetMap().SameAs(Import2->TargetMap())) {printf("[%d] DCI: TargetMaps don't match\n",PID);return;}

  if(Import1->NumSameIDs() != Import2->NumSameIDs()) {printf("[%d] DCI NumSameIDs() mismatch %d vs. %d\n",PID,Import1->NumSameIDs(),Import2->NumSameIDs());flag=false;}

  if(Import1->NumPermuteIDs() != Import2->NumPermuteIDs()) {printf("[%d] DCI NumPermuteIDs() mismatch %d vs. %d\n",PID,Import1->NumPermuteIDs(),Import2->NumPermuteIDs()); flag=false;}

  if(Import1->NumExportIDs() != Import2->NumExportIDs()) {printf("[%d] DCI NumExportIDs() mismatch %d vs. %d\n",PID,Import1->NumExportIDs(),Import2->NumExportIDs()); flag=false;}

  if(Import1->NumRemoteIDs() != Import2->NumRemoteIDs()) {printf("[%d] DCI NumRemoteIDs() mismatch %d vs. %d\n",PID,Import1->NumRemoteIDs(),Import2->NumRemoteIDs()); flag=false;}

  if(Import1->NumSend() != Import2->NumSend()) {printf("[%d] DCI NumSend() mismatch %d vs. %d\n",PID,Import1->NumSend(),Import2->NumSend()); flag=false;}

  if(Import1->NumRecv() != Import2->NumRecv()) {printf("[%d] DCI NumRecv() mismatch %d vs. %d\n",PID,Import1->NumRecv(),Import2->NumRecv()); flag=false;}


  if(flag) printf("[%d] DCI Importers compare OK\n",PID);    
  fflush(stdout);
  Import1->SourceMap().Comm().Barrier();
  Import1->SourceMap().Comm().Barrier();
  Import1->SourceMap().Comm().Barrier();
  if(!flag) exit(1);
}



//------------------------------------
CrsMatrixStruct::CrsMatrixStruct()
 : numRows(0), numEntriesPerRow(NULL), indices(NULL), values(NULL),
   remote(NULL), numRemote(0), importColMap(NULL), rowMap(NULL), colMap(NULL),
   domainMap(NULL), importMatrix(NULL), origMatrix(NULL)
{
}

CrsMatrixStruct::~CrsMatrixStruct()
{
  deleteContents();
}

void CrsMatrixStruct::deleteContents()
{
  numRows = 0;
  delete [] numEntriesPerRow; numEntriesPerRow = NULL;
  delete [] indices; indices = NULL;
  delete [] values; values = NULL;
  delete [] remote; remote = NULL;
  numRemote = 0;
  delete importMatrix; importMatrix=0;
  // origMatrix is not owned by me, so don't delete
  origMatrix=0;
  targetMapToOrigRow.resize(0);
  targetMapToImportRow.resize(0);
}

int dumpCrsMatrixStruct(const CrsMatrixStruct& M)
{
  std::cout << "proc " << M.rowMap->Comm().MyPID()<<std::endl;
  std::cout << "numRows: " << M.numRows<<std::endl;
  for(int i=0; i<M.numRows; ++i) {
    for(int j=0; j<M.numEntriesPerRow[i]; ++j) {
      if (M.remote[i]) {
        std::cout << "  *"<<M.rowMap->GID64(i)<<"   "
             <<M.importColMap->GID64(M.indices[i][j])<<"   "<<M.values[i][j]<<std::endl;
      }
      else {
        std::cout << "   "<<M.rowMap->GID64(i)<<"   "
             <<M.colMap->GID64(M.indices[i][j])<<"   "<<M.values[i][j]<<std::endl;
      }
    }
  }
  return(0);
}

CrsWrapper_Epetra_CrsMatrix::CrsWrapper_Epetra_CrsMatrix(Epetra_CrsMatrix& epetracrsmatrix)
 : ecrsmat_(epetracrsmatrix)
{
}

CrsWrapper_Epetra_CrsMatrix::~CrsWrapper_Epetra_CrsMatrix()
{
}

const Epetra_Map&
CrsWrapper_Epetra_CrsMatrix::RowMap() const
{
  return ecrsmat_.RowMap();
}

bool CrsWrapper_Epetra_CrsMatrix::Filled()
{
  return ecrsmat_.Filled();
}

#ifndef EPETRA_NO_32BIT_GLOBAL_INDICES
int
CrsWrapper_Epetra_CrsMatrix::InsertGlobalValues(int GlobalRow, int NumEntries, double* Values, int* Indices)
{
  return ecrsmat_.InsertGlobalValues(GlobalRow, NumEntries, Values, Indices);
}

int
CrsWrapper_Epetra_CrsMatrix::SumIntoGlobalValues(int GlobalRow, int NumEntries, double* Values, int* Indices)
{
  return ecrsmat_.SumIntoGlobalValues(GlobalRow, NumEntries, Values, Indices);
}
#endif

#ifndef EPETRA_NO_64BIT_GLOBAL_INDICES
int
CrsWrapper_Epetra_CrsMatrix::InsertGlobalValues(long long GlobalRow, int NumEntries, double* Values, long long* Indices)
{
  return ecrsmat_.InsertGlobalValues(GlobalRow, NumEntries, Values, Indices);
}

int
CrsWrapper_Epetra_CrsMatrix::SumIntoGlobalValues(long long GlobalRow, int NumEntries, double* Values, long long* Indices)
{
  return ecrsmat_.SumIntoGlobalValues(GlobalRow, NumEntries, Values, Indices);
}
#endif


//------------------------------------

template<typename int_type>
CrsWrapper_GraphBuilder<int_type>::CrsWrapper_GraphBuilder(const Epetra_Map& emap)
 : graph_(),
   rowmap_(emap),
   max_row_length_(0)
{
  int num_rows = emap.NumMyElements();
  int_type* rows = 0;
  emap.MyGlobalElementsPtr(rows);

  for(int i=0; i<num_rows; ++i) {
    graph_[rows[i]] = new std::set<int_type>;
  }
}

template<typename int_type>
CrsWrapper_GraphBuilder<int_type>::~CrsWrapper_GraphBuilder()
{
  typename std::map<int_type,std::set<int_type>*>::iterator
    iter = graph_.begin(), iter_end = graph_.end();
  for(; iter!=iter_end; ++iter) {
    delete iter->second;
  }

  graph_.clear();
}

template<typename int_type>
bool CrsWrapper_GraphBuilder<int_type>::Filled()
{
  return false;
}

template<typename int_type>
int
CrsWrapper_GraphBuilder<int_type>::InsertGlobalValues(int_type GlobalRow, int NumEntries, double* Values, int_type* Indices)
{
  typename std::map<int_type,std::set<int_type>*>::iterator
    iter = graph_.find(GlobalRow);

  if (iter == graph_.end()) return(-1);

  std::set<int_type>& cols = *(iter->second);

  for(int i=0; i<NumEntries; ++i) {
    cols.insert(Indices[i]);
  }

  int row_length = cols.size();
  if (row_length > max_row_length_) max_row_length_ = row_length;

  return(0);
}

template<typename int_type>
int
CrsWrapper_GraphBuilder<int_type>::SumIntoGlobalValues(int_type GlobalRow, int NumEntries, double* Values, int_type* Indices)
{
  return InsertGlobalValues(GlobalRow, NumEntries, Values, Indices);
}

template<typename int_type>
std::map<int_type,std::set<int_type>*>&
CrsWrapper_GraphBuilder<int_type>::get_graph()
{
  return graph_;
}

template<typename int_type>
void insert_matrix_locations(CrsWrapper_GraphBuilder<int_type>& graphbuilder,
                              Epetra_CrsMatrix& C)
{
  int max_row_length = graphbuilder.get_max_row_length();
  if (max_row_length < 1) return;

  std::vector<int_type> indices(max_row_length);
  int_type* indices_ptr = &indices[0];
  std::vector<double> zeros(max_row_length, 0.0);
  double* zeros_ptr = &zeros[0];

  std::map<int_type,std::set<int_type>*>& graph = graphbuilder.get_graph();

  typename std::map<int_type,std::set<int_type>*>::iterator
    iter = graph.begin(), iter_end = graph.end();

  for(; iter!=iter_end; ++iter) {
    int_type row = iter->first;
    std::set<int_type>& cols = *(iter->second);
    int num_entries = cols.size();

    typename std::set<int_type>::iterator
      col_iter = cols.begin(), col_end = cols.end();
    for(int j=0; col_iter!=col_end; ++col_iter, ++j) {
      indices_ptr[j] = *col_iter;
    }

    C.InsertGlobalValues(row, num_entries, zeros_ptr, indices_ptr);
  }
}

template<typename int_type>
void Tpack_outgoing_rows(const Epetra_CrsMatrix& mtx,
                        const std::vector<int_type>& proc_col_ranges,
                        std::vector<int_type>& send_rows,
                        std::vector<int>& rows_per_send_proc)
{
  const Epetra_Map& rowmap = mtx.RowMap();
  int numrows = mtx.NumMyRows();
  const Epetra_CrsGraph& graph = mtx.Graph();
  int rowlen = 0;
  int* col_indices = NULL;
  int_type* Tcol_indices = NULL;
  int num_col_ranges = proc_col_ranges.size()/2;
  rows_per_send_proc.resize(num_col_ranges);
  send_rows.clear();
  for(int nc=0; nc<num_col_ranges; ++nc) {
    int_type first_col = proc_col_ranges[nc*2];
    int_type last_col = proc_col_ranges[nc*2+1];
    int num_send_rows = 0;
    for(int i=0; i<numrows; ++i) {
      int_type grow = (int_type) rowmap.GID64(i);
      if (mtx.Filled()) {
        const Epetra_Map& colmap = mtx.ColMap();
        graph.ExtractMyRowView(i, rowlen, col_indices);
        for(int j=0; j<rowlen; ++j) {
          int_type col = (int_type) colmap.GID64(col_indices[j]);
          if (first_col <= col && last_col >= col) {
            ++num_send_rows;
            send_rows.push_back(grow);
            break;
          }
        }
      }
      else {
        graph.ExtractGlobalRowView(grow, rowlen, Tcol_indices);
        for(int j=0; j<rowlen; ++j) {
          if (first_col <= Tcol_indices[j] && last_col >= Tcol_indices[j]) {
            ++num_send_rows;
            send_rows.push_back(grow);
            break;
          }
        }
      }
    }
    rows_per_send_proc[nc] = num_send_rows;
  }
}

#ifndef EPETRA_NO_32BIT_GLOBAL_INDICES
void pack_outgoing_rows(const Epetra_CrsMatrix& mtx,
                        const std::vector<int>& proc_col_ranges,
                        std::vector<int>& send_rows,
                        std::vector<int>& rows_per_send_proc)
{
  if(mtx.RowMatrixRowMap().GlobalIndicesInt()) {
    Tpack_outgoing_rows<int>(mtx, proc_col_ranges, send_rows, rows_per_send_proc);
  }
  else {
    throw "EpetraExt::pack_outgoing_rows: Global indices not int";
  }
}
#endif

#ifndef EPETRA_NO_64BIT_GLOBAL_INDICES
void pack_outgoing_rows(const Epetra_CrsMatrix& mtx,
                        const std::vector<long long>& proc_col_ranges,
                        std::vector<long long>& send_rows,
                        std::vector<int>& rows_per_send_proc)
{
  if(mtx.RowMatrixRowMap().GlobalIndicesLongLong()) {
    Tpack_outgoing_rows<long long>(mtx, proc_col_ranges, send_rows, rows_per_send_proc);
  }
  else {
    throw "EpetraExt::pack_outgoing_rows: Global indices not long long";
  }
}
#endif

#ifndef EPETRA_NO_32BIT_GLOBAL_INDICES
template<>
std::pair<int,int> get_col_range<int>(const Epetra_Map& emap)
 {
  if(emap.GlobalIndicesInt())
    return std::make_pair(emap.MinMyGID(),emap.MaxMyGID());
  else
    throw "EpetraExt::get_col_range<int>: Unknown Global Indices for Epetra_Map";
}
#endif

#ifndef EPETRA_NO_64BIT_GLOBAL_INDICES
template<>
std::pair<long long,long long> get_col_range<long long>(const Epetra_Map& emap)
{
  if(emap.GlobalIndicesLongLong())
    return std::make_pair(emap.MinMyGID64(),emap.MaxMyGID64());
  else
    throw "EpetraExt::get_col_range<long long>: Unknown Global Indices for Epetra_Map";
}
#endif

template<typename int_type>
std::pair<int_type,int_type> Tget_col_range(const Epetra_CrsMatrix& mtx)
{
  std::pair<int_type,int_type> col_range;
  if (mtx.Filled()) {
    col_range = get_col_range<int_type>(mtx.ColMap());
  }
  else {
    const Epetra_Map& row_map = mtx.RowMap();
    col_range.first = row_map.MaxMyGID64();
    col_range.second = row_map.MinMyGID64();
    int rowlen = 0;
    int_type* col_indices = NULL;
    const Epetra_CrsGraph& graph = mtx.Graph();
    for(int i=0; i<row_map.NumMyElements(); ++i) {
      graph.ExtractGlobalRowView((int_type) row_map.GID64(i), rowlen, col_indices);
      for(int j=0; j<rowlen; ++j) {
        if (col_indices[j] < col_range.first) col_range.first = col_indices[j];
        if (col_indices[j] > col_range.second) col_range.second = col_indices[j];
      }
    }
  }

  return col_range;
}

#ifndef EPETRA_NO_32BIT_GLOBAL_INDICES
template<>
std::pair<int,int> get_col_range<int>(const Epetra_CrsMatrix& mtx)
{
  if(mtx.RowMatrixRowMap().GlobalIndicesInt())
    return Tget_col_range<int>(mtx);
  else
    throw "EpetraExt::get_col_range<int>: Unknown Global Indices for Epetra_CrsMatrix";
}
#endif

#ifndef EPETRA_NO_64BIT_GLOBAL_INDICES
template<>
std::pair<long long,long long> get_col_range<long long>(const Epetra_CrsMatrix& mtx)
{
  if(mtx.RowMatrixRowMap().GlobalIndicesLongLong())
    return Tget_col_range<long long>(mtx);
  else
    throw "EpetraExt::get_col_range<long long>: Unknown Global Indices for Epetra_CrsMatrix";
}
#endif


/**********************************************************************************************/
/**********************************************************************************************/
/**********************************************************************************************/
#ifdef HAVE_MPI
template <typename MyType>
void boundary_exchange(const Epetra_MpiComm Comm, MPI_Datatype DataType, 
           int NumSends, const int * SendProcs, const int * SendSizes, MyType* SendBuffer, 
           int NumRecvs, const int * RecvProcs, const int * RecvSizes, MyType* RecvBuffer,int SizeOfPacket,int msg_tag)
{  

  MPI_Comm comm = Comm.Comm();
  std::vector<MPI_Request> requests(NumRecvs);
  std::vector<MPI_Status>  status(NumRecvs);

  int i,num_waits=0,MyPID=Comm.MyPID();
  int start, self_recv_len=-1,self_recv_start=-1, self_send_start=-1;
  
  // Default send/recv size if the Sizes arrays are NULL.
  int mysendsize=1, myrecvsize=1;

  // Post Recvs
  start=0;
  for(i=0; i<NumRecvs; i++){
    if(RecvSizes) myrecvsize=RecvSizes[i]*SizeOfPacket;
    if(RecvProcs[i] != MyPID) {
      MPI_Irecv(RecvBuffer + start, myrecvsize, DataType, RecvProcs[i], msg_tag, comm, &requests[num_waits]);
      num_waits++;
    }
    else {
      self_recv_len = myrecvsize;
      self_recv_start=start;
    } 
    start+=myrecvsize;
  }

  // Do sends
  start=0;
  for(i=0; i<NumSends; i++){
    if(SendSizes) mysendsize=SendSizes[i]*SizeOfPacket;
    if(SendProcs[i] != MyPID)
      MPI_Send(SendBuffer + start, mysendsize,DataType,SendProcs[i],msg_tag,comm);
    else 
      self_send_start=start;
    start+=mysendsize;
  }

  // Self-copy (if needed)
  if(self_recv_len != -1)
    memcpy(RecvBuffer+self_recv_start,SendBuffer+self_send_start,self_recv_len*sizeof(MyType)*SizeOfPacket);

  // Wait
  if(NumRecvs > 0)
    MPI_Waitall(num_waits, &requests[0],&status[0]);
}
#endif


#ifdef HAVE_MPI
template <typename MyType>
void boundary_exchange_varsize(const Epetra_MpiComm Comm, MPI_Datatype DataType, 
             int NumSends, const int * SendProcs, const int * SendSizes, MyType* SendBuffer, 
             int NumRecvs, const int * RecvProcs, int * RecvSizes, MyType*& RecvBuffer,int SizeOfPacket,int msg_tag)
{  

  int i,rbuffersize=0;

  // Do a first round of boundary exchange with the the SendBuffer sizes
  boundary_exchange<int>(Comm,MPI_INT,NumSends,SendProcs,(int*)0,const_cast<int*>(SendSizes),NumRecvs,RecvProcs,(int*)0,RecvSizes,1,msg_tag);

  // Allocate the RecvBuffer 
  for(i=0; i<NumRecvs; i++) rbuffersize+=RecvSizes[i]*SizeOfPacket;
  RecvBuffer = new MyType[rbuffersize];

  // Do a second round of boundary exchange to trade the actual values
  boundary_exchange<MyType>(Comm,DataType,NumSends,SendProcs,SendSizes,SendBuffer,NumRecvs,RecvProcs,RecvSizes,RecvBuffer,SizeOfPacket,msg_tag+100);
}
#endif


//=========================================================================
//=========================================================================
//=========================================================================
LightweightMapData::LightweightMapData():
  Epetra_Data(),
  IndexBase_(0),
#ifndef EPETRA_NO_32BIT_GLOBAL_INDICES
  LIDHash_int_(0),
#endif
#ifndef EPETRA_NO_64BIT_GLOBAL_INDICES
  LIDHash_LL_(0),
#endif
  CopyMap_(0)
{
}
//=========================================================================
LightweightMapData::~LightweightMapData(){
#ifndef EPETRA_NO_32BIT_GLOBAL_INDICES
  delete LIDHash_int_;
#endif
#ifndef EPETRA_NO_64BIT_GLOBAL_INDICES
  delete LIDHash_LL_;
#endif
  delete CopyMap_;
}

//=========================================================================
LightweightMap::LightweightMap():Data_(0),IsLongLong(false),IsInt(false){;}

//=========================================================================
#ifndef EPETRA_NO_32BIT_GLOBAL_INDICES
void LightweightMap::Construct_int(int NumGlobalElements,int NumMyElements, const int * MyGlobalElements, long long IndexBase, bool GenerateHash)
{
  Data_=new LightweightMapData();
  Data_->MyGlobalElements_int_.resize(NumMyElements);

  // Build the hash table
  if(GenerateHash) Data_->LIDHash_int_ = new Epetra_HashTable<int>(NumMyElements + 1 );
    for(int i=0; i < NumMyElements; ++i ) {
      Data_->MyGlobalElements_int_[i]=MyGlobalElements[i];
      if(GenerateHash) Data_->LIDHash_int_->Add(MyGlobalElements[i], i);
    }  
  IsLongLong = false;
  IsInt = true;
}
#endif

#ifndef EPETRA_NO_64BIT_GLOBAL_INDICES
void LightweightMap::Construct_LL(long long NumGlobalElements,int NumMyElements, const long long * MyGlobalElements, long long IndexBase, bool GenerateHash)
{
  Data_=new LightweightMapData();
  Data_->MyGlobalElements_LL_.resize(NumMyElements);

  // Build the hash table
  if(GenerateHash) Data_->LIDHash_LL_ = new Epetra_HashTable<long long>(NumMyElements + 1 );
    for(int i=0; i < NumMyElements; ++i ) {
      Data_->MyGlobalElements_LL_[i]=MyGlobalElements[i];
      if(GenerateHash) Data_->LIDHash_LL_->Add(MyGlobalElements[i], i);
    }  
  IsLongLong = true;
  IsInt = false;
}
#endif

#ifndef EPETRA_NO_32BIT_GLOBAL_INDICES
LightweightMap::LightweightMap(int NumGlobalElements,int NumMyElements, const int * MyGlobalElements, int IndexBase, bool GenerateHash)
{
  Construct_int(NumGlobalElements, NumMyElements, MyGlobalElements, IndexBase, GenerateHash);
}
#endif

#ifndef EPETRA_NO_64BIT_GLOBAL_INDICES
LightweightMap::LightweightMap(long long NumGlobalElements,int NumMyElements, const long long * MyGlobalElements, int IndexBase, bool GenerateHash)
{
  Construct_LL(NumGlobalElements, NumMyElements, MyGlobalElements, IndexBase, GenerateHash);
}

LightweightMap::LightweightMap(long long NumGlobalElements,int NumMyElements, const long long * MyGlobalElements, long long IndexBase, bool GenerateHash)
{
  Construct_LL(NumGlobalElements, NumMyElements, MyGlobalElements, IndexBase, GenerateHash);
}
#endif

//=========================================================================
LightweightMap::LightweightMap(const Epetra_Map & Map)
{
  Data_=new LightweightMapData();
  Data_->CopyMap_=new Epetra_Map(Map);
  IsLongLong = Map.GlobalIndicesLongLong();
  IsInt = Map.GlobalIndicesInt();
}

//=========================================================================
LightweightMap::LightweightMap(const LightweightMap& map)
  : Data_(map.Data_)
{
  Data_->IncrementReferenceCount();
  IsLongLong = map.IsLongLong;
  IsInt = map.IsInt;
}

//=========================================================================
LightweightMap::~LightweightMap(){
  CleanupData();
}

//=========================================================================
LightweightMap & LightweightMap::operator= (const LightweightMap & map)
{
  if((this != &map) && (Data_ != map.Data_)) {
    CleanupData();
    Data_ = map.Data_;
    Data_->IncrementReferenceCount();
  }
  IsLongLong = map.IsLongLong;
  IsInt = map.IsInt;
  return(*this);
}

//=========================================================================
void LightweightMap::CleanupData(){
  if(Data_){
    Data_->DecrementReferenceCount();
    if(Data_->ReferenceCount() == 0) {
      delete Data_;
    }
  }
}

#ifndef EPETRA_NO_32BIT_GLOBAL_INDICES
void LightweightMap::MyGlobalElementsPtr(int *& MyGlobalElementList) const {
  MyGlobalElementList = Data_->MyGlobalElements_int_.size() ? &Data_->MyGlobalElements_int_.front() : 0;
}
#endif
#ifndef EPETRA_NO_64BIT_GLOBAL_INDICES
void LightweightMap::MyGlobalElementsPtr(long long *& MyGlobalElementList) const {
  MyGlobalElementList = Data_->MyGlobalElements_LL_.size() ? &Data_->MyGlobalElements_LL_.front() : 0;
}
#endif

//=========================================================================
int LightweightMap::NumMyElements() const {
  if(Data_->CopyMap_) return Data_->CopyMap_->NumMyElements();
#ifndef EPETRA_NO_32BIT_GLOBAL_INDICES
  if(IsInt)
    return Data_->MyGlobalElements_int_.size();
  else
#endif
#ifndef EPETRA_NO_64BIT_GLOBAL_INDICES
  if(IsLongLong)
    return Data_->MyGlobalElements_LL_.size();
  else
#endif
    throw "EpetraExt::LightweightMap::NumMyElements: Global indices unknowns";
}

//=========================================================================
#ifndef EPETRA_NO_32BIT_GLOBAL_INDICES
int LightweightMap::LID(int GID) const {
  if(Data_->CopyMap_) return Data_->CopyMap_->LID(GID);
  if(IsInt)
    return Data_->LIDHash_int_->Get(GID);
  else if(IsLongLong)
    throw "EpetraExt::LightweightMap::LID: Int version called for long long map";
  else
    throw "EpetraExt::LightweightMap::LID: unknown GID type";
}
#endif
#ifndef EPETRA_NO_64BIT_GLOBAL_INDICES
int LightweightMap::LID(long long GID) const {

  if(Data_->CopyMap_) return Data_->CopyMap_->LID(GID);
  if(IsLongLong)
    return Data_->LIDHash_LL_->Get(GID);
  else if(IsInt)
    throw "EpetraExt::LightweightMap::LID: Long long version called for int map";
  else
    throw "EpetraExt::LightweightMap::LID: unknown GID type";
}
#endif

//=========================================================================
#ifndef EPETRA_NO_32BIT_GLOBAL_INDICES
int LightweightMap::GID(int LID) const {
  if(Data_->CopyMap_) return Data_->CopyMap_->GID(LID);
  if(LID < 0 || LID > (int)Data_->MyGlobalElements_int_.size()) return -1;
  return Data_->MyGlobalElements_int_[LID];
}
#endif
long long LightweightMap::GID64(int LID) const {
  if(Data_->CopyMap_) return Data_->CopyMap_->GID64(LID);
#ifndef EPETRA_NO_32BIT_GLOBAL_INDICES
  if(IsInt) {
    if(LID < 0 || LID > (int)Data_->MyGlobalElements_int_.size()) return -1;
    return Data_->MyGlobalElements_int_[LID];
  }
  else
#endif
#ifndef EPETRA_NO_64BIT_GLOBAL_INDICES
  if(IsLongLong) {
    if(LID < 0 || LID > (int)Data_->MyGlobalElements_LL_.size()) return -1;
    return Data_->MyGlobalElements_LL_[LID];
  }
  else
#endif
    throw "EpetraExt::LightweightMap::GID64: Global indices unknown.";
}

//=========================================================================
#ifndef EPETRA_NO_32BIT_GLOBAL_INDICES
int* LightweightMap::MyGlobalElements() const {
  if(Data_->CopyMap_) return Data_->CopyMap_->MyGlobalElements();
  else if(Data_->MyGlobalElements_int_.size()>0) return const_cast<int*>(&Data_->MyGlobalElements_int_[0]);
  else return 0;
}
#endif
#ifndef EPETRA_NO_64BIT_GLOBAL_INDICES
long long* LightweightMap::MyGlobalElements64() const {
  if(Data_->CopyMap_) return Data_->CopyMap_->MyGlobalElements64();
  else if(Data_->MyGlobalElements_LL_.size()>0) return const_cast<long long*>(&Data_->MyGlobalElements_LL_[0]);
  else return 0;
}
#endif

//=========================================================================
int LightweightMap::MinLID() const {
  if(Data_->CopyMap_) return Data_->CopyMap_->MinLID();
  else return 0;
}

//=========================================================================
int LightweightMap::MaxLID() const {
  if(Data_->CopyMap_) return Data_->CopyMap_->MaxLID();
  else {
#ifndef EPETRA_NO_32BIT_GLOBAL_INDICES
  if(IsInt)
    return Data_->MyGlobalElements_int_.size() - 1;
  else
#endif
#ifndef EPETRA_NO_64BIT_GLOBAL_INDICES
  if(IsLongLong)
    return Data_->MyGlobalElements_LL_.size() - 1;
  else
#endif
    throw "EpetraExt::LightweightMap::MaxLID: Global indices unknowns";
  }   
}


//=========================================================================
//=========================================================================
//=========================================================================
RemoteOnlyImport::RemoteOnlyImport(const Epetra_Import & Importer, LightweightMap & RemoteOnlyTargetMap)
{
  int i;

  // Build an "Importer" that only takes the remote parts of the Importer.
  SourceMap_=&Importer.SourceMap();
  TargetMap_=&RemoteOnlyTargetMap;

  // Pull data from the Importer
  NumSend_            = Importer.NumSend();
  NumRemoteIDs_       = Importer.NumRemoteIDs();
  NumExportIDs_       = Importer.NumExportIDs();
  Distor_             = &Importer.Distributor();
  int * OldRemoteLIDs = Importer.RemoteLIDs();
  int * OldExportLIDs = Importer.ExportLIDs();
  int * OldExportPIDs = Importer.ExportPIDs();
  
  // Sanity Check
  if(NumRemoteIDs_ != RemoteOnlyTargetMap.NumMyElements())
    throw std::runtime_error("RemoteOnlyImport: Importer doesn't match RemoteOnlyTargetMap for number of remotes.");

  // Copy the ExportIDs_, since they don't change
  ExportLIDs_ = new int[NumExportIDs_];
  ExportPIDs_ = new int[NumExportIDs_];
  for(i=0; i<NumExportIDs_; i++) {
    ExportLIDs_[i] = OldExportLIDs[i];
    ExportPIDs_[i] = OldExportPIDs[i];
  }

  // The RemoteIDs, on the other hand, do change.  So let's do this right.
  // Note: We might be able to bypass the LID call by just indexing off the Same and Permute GIDs, but at the moment this
  // is fast enough not to worry about it.
  RemoteLIDs_ = new int[NumRemoteIDs_];
  if(TargetMap_->GlobalIndicesInt()) {
    for(i=0; i<NumRemoteIDs_; i++) 
      RemoteLIDs_[i] = TargetMap_->LID( (int) Importer.TargetMap().GID64(OldRemoteLIDs[i]));
  }
  else if(TargetMap_->GlobalIndicesLongLong()) {
    for(i=0; i<NumRemoteIDs_; i++) 
      RemoteLIDs_[i] = TargetMap_->LID(Importer.TargetMap().GID64(OldRemoteLIDs[i]));
  }
  else
    throw std::runtime_error("RemoteOnlyImport: TargetMap_ index type unknown.");

  // Nowe we make sure these guys are in sorted order.  AztecOO, ML and all that jazz.
  for(i=0; i<NumRemoteIDs_-1; i++) 
    if(RemoteLIDs_[i] > RemoteLIDs_[i+1])
      throw std::runtime_error("RemoteOnlyImport: Importer and RemoteOnlyTargetMap order don't match.");
}

//=========================================================================
RemoteOnlyImport::~RemoteOnlyImport()
{
  delete [] ExportLIDs_;
  delete [] ExportPIDs_;
  delete [] RemoteLIDs_;
  // Don't delete the Distributor, SourceMap_ or TargetMap_ - those were shallow copies
}

//=========================================================================
//=========================================================================
//=========================================================================

template <class GO>
void MakeColMapAndReindexSort(int& NumRemoteColGIDs, GO*& RemoteColindices,
    std::vector<int>& RemotePermuteIDs, std::vector<int>& RemoteOwningPIDs);

template <>
void MakeColMapAndReindexSort<int>(int& NumRemoteColGIDs, int*& RemoteColindices,
    std::vector<int>& RemotePermuteIDs, std::vector<int>& RemoteOwningPIDs)
{
  // Sort External column indices so that all columns coming from a given remote processor are contiguous
  int NLists = 2;
  int* SortLists[3]; // this array is allocated on the stack, and so we won't need to delete it.
  if(NumRemoteColGIDs > 0) {
    SortLists[0] = RemoteColindices;    
    SortLists[1] = &RemotePermuteIDs[0];
    Epetra_Util::Sort(true, NumRemoteColGIDs, &RemoteOwningPIDs[0], 0, 0, NLists, SortLists);
  }


  bool SortGhostsAssociatedWithEachProcessor_ = false;
  if (SortGhostsAssociatedWithEachProcessor_) {
    // Sort external column indices so that columns from a given remote processor are not only contiguous
    // but also in ascending order. NOTE: I don't know if the number of externals associated
    // with a given remote processor is known at this point ... so I count them here.

    NLists=1;
    int StartCurrent, StartNext;
    StartCurrent = 0; StartNext = 1;
    while ( StartNext < NumRemoteColGIDs ) {
      if (RemoteOwningPIDs[StartNext]==RemoteOwningPIDs[StartNext-1]) StartNext++;
      else {
  SortLists[0] =  &RemotePermuteIDs[StartCurrent];
  Epetra_Util::Sort(true,StartNext-StartCurrent, &(RemoteColindices[StartCurrent]),0,0,NLists,SortLists);
        StartCurrent = StartNext; StartNext++;
      }
    }
    SortLists[0] =  &RemotePermuteIDs[StartCurrent];
    Epetra_Util::Sort(true, StartNext-StartCurrent, &(RemoteColindices[StartCurrent]), 0, 0, NLists, SortLists);
  }
}

template <>
void MakeColMapAndReindexSort<long long>(int& NumRemoteColGIDs, long long*& RemoteColindices,
    std::vector<int>& RemotePermuteIDs, std::vector<int>& RemoteOwningPIDs)
{
  // Sort External column indices so that all columns coming from a given remote processor are contiguous
  if(NumRemoteColGIDs > 0) {
    long long* SortLists_LL[1] = {RemoteColindices};
  int* SortLists_int[1] = {&RemotePermuteIDs[0]};
    Epetra_Util::Sort(true, NumRemoteColGIDs, &RemoteOwningPIDs[0], 0, 0, 1, SortLists_int, 1, SortLists_LL);
  }

  bool SortGhostsAssociatedWithEachProcessor_ = false;
  if (SortGhostsAssociatedWithEachProcessor_) {
    // Sort external column indices so that columns from a given remote processor are not only contiguous
    // but also in ascending order. NOTE: I don't know if the number of externals associated
    // with a given remote processor is known at this point ... so I count them here.

    int NLists=1;
    int StartCurrent, StartNext;
    StartCurrent = 0; StartNext = 1;
    while ( StartNext < NumRemoteColGIDs ) {
      if (RemoteOwningPIDs[StartNext]==RemoteOwningPIDs[StartNext-1]) StartNext++;
      else {
        int* SortLists[1] = {&RemotePermuteIDs[StartCurrent]};
        Epetra_Util::Sort(true,StartNext-StartCurrent, &(RemoteColindices[StartCurrent]),0,0,NLists,SortLists, 0, 0);
        StartCurrent = StartNext; StartNext++;
      }
    }
  int* SortLists[1] =  {&RemotePermuteIDs[StartCurrent]};
    Epetra_Util::Sort(true, StartNext-StartCurrent, &(RemoteColindices[StartCurrent]), 0, 0, NLists, SortLists, 0, 0);
  }
}

template <class GO>
int LightweightCrsMatrix::MakeColMapAndReindex(std::vector<int> owningPIDs, std::vector<GO> Gcolind)
{
  int i,j;

#ifdef ENABLE_MMM_TIMINGS
  using Teuchos::TimeMonitor;
  Teuchos::RCP<Teuchos::TimeMonitor> MM = Teuchos::rcp(new TimeMonitor(*TimeMonitor::getNewTimer("EpetraExt: LWCRS-3.1")));
#endif

  // Scan all column indices and sort into two groups: 
  // Local:  those whose GID matches a GID of the domain map on this processor and
  // Remote: All others.
  int numDomainElements = DomainMap_.NumMyElements();
  std::vector<bool> LocalGIDs(numDomainElements,false);

  bool DoSizes = !DomainMap_.ConstantElementSize(); // If not constant element size, then error
  if(DoSizes) EPETRA_CHK_ERR(-1);

  // In principle it is good to have RemoteGIDs and RemoteGIDList be as long as the number of remote GIDs
  // on this processor, but this would require two passes through the column IDs, so we make it the max of 100
  // and the number of block rows.
  int numMyBlockRows;
  if(use_lw) numMyBlockRows = RowMapLW_->NumMyElements();
  else numMyBlockRows = RowMapEP_->NumMyElements();

  int  hashsize = numMyBlockRows; if (hashsize < 100) hashsize = 100;
  Epetra_HashTable<GO> RemoteGIDs(hashsize); 
  std::vector<GO>  RemoteGIDList;     RemoteGIDList.reserve(hashsize);
  std::vector<int> RemoteOwningPIDs;  RemoteOwningPIDs.reserve(hashsize);
    
  // In order to do the map reindexing inexpensively, we clobber the GIDs during this pass.  For *local* GID's we clobber them
  // with their LID in the domainMap.  For *remote* GIDs, we clobber them with (numDomainElements+NumRemoteColGIDs) before the increment of
  // the remote count.  These numberings will be separate because no local LID is greater than numDomainElements. 
  int NumLocalColGIDs = 0;
  int NumRemoteColGIDs = 0;
  for(i = 0; i < numMyBlockRows; i++) {
    for(j = rowptr_[i]; j < rowptr_[i+1]; j++) {
      GO GID = Gcolind[j];
      // Check if GID matches a row GID
      int LID = DomainMap_.LID(GID);
      if(LID != -1) {
  bool alreadyFound = LocalGIDs[LID];
  if (!alreadyFound) {
          LocalGIDs[LID] = true; // There is a column in the graph associated with this domain map GID
          NumLocalColGIDs++;
  }
  colind_[j] = LID; 
      }
      else {
  GO hash_value=RemoteGIDs.Get(GID);
  if(hash_value  == -1) { // This means its a new remote GID
    int PID = owningPIDs[j];
    if(PID==-1) printf("[%d] ERROR: Remote PID should not be -1\n",DomainMap_.Comm().MyPID());
    colind_[j] = numDomainElements + NumRemoteColGIDs;
    RemoteGIDs.Add(GID, NumRemoteColGIDs);
    RemoteGIDList.push_back(GID);
    RemoteOwningPIDs.push_back(PID);
    NumRemoteColGIDs++;
  }
  else
    colind_[j] = numDomainElements + hash_value;    
      }
    }
  }

  // Possible short-circuit:  If all domain map GIDs are present as column indices, then set ColMap=domainMap and quit
  if (DomainMap_.Comm().NumProc()==1) {     
    if (NumRemoteColGIDs!=0) {
      throw "Some column IDs are not in domainMap.  If matrix is rectangular, you must pass in domainMap to FillComplete";
      // Sanity test: When one processor,there can be no remoteGIDs
    }
    if (NumLocalColGIDs==numDomainElements) {
      ColMap_ = DomainMap_;

      // In this case, we just use the domainMap's indices, which is, not coincidently, what we clobbered colind_ with up above anyway. 
      // No further reindexing is needed.
      return(0); 
    }
  }
      
  // Now build integer array containing column GIDs
  // Build back end, containing remote GIDs, first
  int numMyBlockCols = NumLocalColGIDs + NumRemoteColGIDs;
  typename Epetra_GIDTypeSerialDenseVector<GO>::impl Colindices;
  if(numMyBlockCols > 0) 
    Colindices.Size(numMyBlockCols);
  GO* RemoteColindices = Colindices.Values() + NumLocalColGIDs; // Points to back end of Colindices

  for(i = 0; i < NumRemoteColGIDs; i++) 
    RemoteColindices[i] = RemoteGIDList[i]; 

  // Build permute array for *remote* reindexing.
  std::vector<int> RemotePermuteIDs(NumRemoteColGIDs);
  for(i=0; i<NumRemoteColGIDs; i++) RemotePermuteIDs[i]=i;

  MakeColMapAndReindexSort<GO>(NumRemoteColGIDs, RemoteColindices, RemotePermuteIDs, RemoteOwningPIDs);

  // Reverse the permutation to get the information we actually care about
  std::vector<int> ReverseRemotePermuteIDs(NumRemoteColGIDs);
  for(i=0; i<NumRemoteColGIDs; i++) ReverseRemotePermuteIDs[RemotePermuteIDs[i]]=i;

  // Build permute array for *local* reindexing.
  bool use_local_permute=false;
  std::vector<int> LocalPermuteIDs(numDomainElements);

  // Now fill front end. Two cases:
  // (1) If the number of Local column GIDs is the same as the number of Local domain GIDs, we
  //     can simply read the domain GIDs into the front part of Colindices, otherwise 
  // (2) We step through the GIDs of the domainMap, checking to see if each domain GID is a column GID.
  //     we want to do this to maintain a consistent ordering of GIDs between the columns and the domain.

  if(NumLocalColGIDs == DomainMap_.NumMyElements()) {
    DomainMap_.MyGlobalElements(Colindices.Values()); // Load Global Indices into first numMyBlockCols elements column GID list
  }
  else {
    GO* MyGlobalElements = 0;
  DomainMap_.MyGlobalElementsPtr(MyGlobalElements);
    int NumLocalAgain = 0;
    use_local_permute = true;    
    for(i = 0; i < numDomainElements; i++) {
      if(LocalGIDs[i]) {
  LocalPermuteIDs[i] = NumLocalAgain;
  Colindices[NumLocalAgain++] = MyGlobalElements[i];
      }
    }
    assert(NumLocalAgain==NumLocalColGIDs); // Sanity test
  }


  // Copy the remote PID list correctly
  ColMapOwningPIDs_.resize(numMyBlockCols);
  ColMapOwningPIDs_.assign(numMyBlockCols,DomainMap_.Comm().MyPID());
  for(int i=0;i<NumRemoteColGIDs;i++)
    ColMapOwningPIDs_[NumLocalColGIDs+i] = RemoteOwningPIDs[i];

#ifdef ENABLE_MMM_TIMINGS
  MM = Teuchos::rcp(new TimeMonitor(*TimeMonitor::getNewTimer("EpetraExt: LWCRS-3.2")));
#endif

  // Make Column map with same element sizes as Domain map 
  LightweightMap temp((GO) -1, numMyBlockCols, Colindices.Values(), (GO) DomainMap_.IndexBase64());
  ColMap_ = temp;


#ifdef ENABLE_MMM_TIMINGS
  MM = Teuchos::rcp(new TimeMonitor(*TimeMonitor::getNewTimer("EpetraExt: LWCRS-3.3")));
#endif

  // Low-cost reindex of the matrix
  for(i=0; i<numMyBlockRows; i++){
    for(j=rowptr_[i]; j<rowptr_[i+1]; j++){
      int ID=colind_[j];
      if(ID < numDomainElements){
  if(use_local_permute) colind_[j] = LocalPermuteIDs[colind_[j]];
  // In the case where use_local_permute==false, we just copy the DomainMap's ordering, which it so happens
  // is what we put in colind_ to begin with.
      }
      else
  colind_[j] =  NumLocalColGIDs + ReverseRemotePermuteIDs[colind_[j]-numDomainElements];
    }
  }

  assert((size_t)ColMap_.NumMyElements() == ColMapOwningPIDs_.size());

  return(0);
}


//=========================================================================
// Template params are <PID,GID>
static inline bool lessthan12(std::pair<int,int> i, std::pair<int,int> j){
  return ((i.first<j.first) || (i.first==j.first && i.second <j.second));
}


template<typename ImportType, typename int_type>
int LightweightCrsMatrix::PackAndPrepareReverseComm(const Epetra_CrsMatrix & SourceMatrix, ImportType & RowImporter,
                std::vector<int> &ReverseSendSizes, std::vector<int_type> &ReverseSendBuffer) {
#ifdef HAVE_MPI
  // Buffer pairs are in (PID,GID) order
  int i,j,k;
  const Epetra_Import *MyImporter= SourceMatrix.Importer();
  if(MyImporter == 0) return -1;
  const Epetra_MpiComm * MpiComm        = dynamic_cast<const Epetra_MpiComm*>(&SourceMatrix.Comm());
  int MyPID                             = MpiComm->MyPID();

  // Things related to messages I and sending in forward mode (RowImporter)
  int NumExportIDs                      = RowImporter.NumExportIDs();
  int* ExportLIDs                       = RowImporter.ExportLIDs();
  int* ExportPIDs                       = RowImporter.ExportPIDs();

  // Things related to messages I am sending in reverse mode (MyImporter)
  Epetra_Distributor& Distor            = MyImporter->Distributor();
  const Epetra_MpiDistributor * MDistor = dynamic_cast<Epetra_MpiDistributor*>(&Distor);
  int NumRecvs                          = MDistor->NumReceives();
  int* RemoteLIDs                       = MyImporter->RemoteLIDs();
  const int * ProcsFrom                 = MDistor->ProcsFrom();
  const int * LengthsFrom               = MDistor->LengthsFrom();

  
  // Get the owning pids in a special way, s.t. ProcsFrom[RemotePIDs[i]] is the guy who owns 
  // RemoteLIDs[j]....
  std::vector<int> RemotePIDOrder(SourceMatrix.NumMyCols(),-1);

  // Now, for each remote ID, record which processor (in ProcsFrom ordering) owns it.
  for(i=0,j=0;i<NumRecvs;i++){
    for(k=0;k<LengthsFrom[i];k++){
      int pid=ProcsFrom[i];
      if(pid!=MyPID) RemotePIDOrder[RemoteLIDs[j]]=i;
      j++;
    }    
  }

  // Step One: Start tacking the (GID,PID) pairs on the std sets
  std::vector<std::set<std::pair<int,int_type> > > ReversePGIDs(NumRecvs);
  int    *rowptr, *colind;
  double *vals;
  EPETRA_CHK_ERR(SourceMatrix.ExtractCrsDataPointers(rowptr,colind,vals));
  

  // Loop over each exported row and add to the temp list
  for(i=0; i < NumExportIDs; i++) {
    int lid = ExportLIDs[i];
    int exp_pid = ExportPIDs[i];    
    for(j=rowptr[lid]; j<rowptr[lid+1]; j++){
      int pid_order = RemotePIDOrder[colind[j]];
      if(pid_order!=-1) {
  int_type gid = (int_type) SourceMatrix.GCID64(colind[j]);
  // This GID is getting shipped off somewhere
  ReversePGIDs[pid_order].insert(std::pair<int,int_type>(exp_pid,gid));
      }
    }
  }

  // Step 2: Count sizes (one too large to avoid std::vector errors)
  ReverseSendSizes.resize(NumRecvs+1);
  int totalsize=0;
  for(i=0; i<NumRecvs; i++) {
    ReverseSendSizes[i] = 2*ReversePGIDs[i].size();
    totalsize += ReverseSendSizes[i];
  }

  // Step 3: Alloc and fill the send buffer (one too large to avoid std::vector errors)
  ReverseSendBuffer.resize(totalsize+1);
  for(i=0, j=0; i<NumRecvs; i++) {
    for(typename std::set<std::pair<int,int_type> >::iterator it=ReversePGIDs[i].begin(); it!=ReversePGIDs[i].end(); it++) {
      ReverseSendBuffer[j]   =  it->first;
      ReverseSendBuffer[j+1] =  it->second;
      j+=2;
    }
  }
#endif

  return 0;
}

//=========================================================================

template<typename int_type>
void build_type3_exports_sort(std::vector<int_type>& ExportGID3, std::vector<int> &ExportPID3, int total_length3);

template<>
void build_type3_exports_sort<int>(std::vector<int>& ExportGID3, std::vector<int> &ExportPID3, int total_length3)
{
  int * companion = &ExportGID3[0];
  Epetra_Util::Sort(true,total_length3,&ExportPID3[0],0,0,1,&companion,0,0);
}

template<>
void build_type3_exports_sort<long long>(std::vector<long long>& ExportGID3, std::vector<int> &ExportPID3, int total_length3)
{
  long long * companion = &ExportGID3[0];
  Epetra_Util::Sort(true,total_length3,&ExportPID3[0],0,0,0,0,1,&companion);
}

template<typename int_type>
int build_type3_exports(int MyPID,int Nrecv, Epetra_BlockMap &DomainMap, std::vector<int> &ReverseRecvSizes, const int_type *ReverseRecvBuffer,  std::vector<int> &ExportLID3, std::vector<int> &ExportPID3){
  int i,j;

  // Estimate total length of procs_to for Type 3
  int total_length3=0;
  for(i=0; i<Nrecv; i++)
    total_length3+=ReverseRecvSizes[i]/2;
  if(total_length3==0) return 0;

  std::vector<int_type> ExportGID3(total_length3);
  ExportLID3.resize(total_length3);
  ExportPID3.resize(total_length3);

  // Build a sorted colmap-style list for Type3 (removing any self-sends)    
  for(i=0,j=0; i<2*total_length3; i+=2) {
    if(ReverseRecvBuffer[i] != MyPID){
      ExportPID3[j]=ReverseRecvBuffer[i];
      ExportGID3[j]=ReverseRecvBuffer[i+1];
      j++;
    }    
  }
  total_length3=j;

  if(total_length3==0) return 0;

  // Sort (ala Epetra_CrsGraph)
  build_type3_exports_sort<int_type>(ExportGID3, ExportPID3, total_length3);
  int StartCurrent, StartNext;
  StartCurrent = 0; StartNext = 1;
  while ( StartNext < total_length3 ) {
    if(ExportPID3[StartNext] == ExportPID3[StartNext-1]) StartNext++;
    else {
      Epetra_Util::Sort(true,StartNext-StartCurrent, &(ExportGID3[StartCurrent]),0,0,0,0, 0, 0);
      StartCurrent = StartNext; StartNext++;
    }
  }
  Epetra_Util::Sort(true,StartNext-StartCurrent, &(ExportGID3[StartCurrent]),0,0,0,0, 0, 0);
  

  /*  printf("[%d] Type 3 Sorted= ",MyComm.MyPID());
  for(i=0; i<total_length3; i++)
    printf("(--,%2d,%2d) ",ExportGID3[i],ExportPID3[i]);
  printf("\n");
  fflush(stdout);*/


  // Uniq & resize
  for(i=1,j=1; i<total_length3; i++){
    if(ExportPID3[i]!=ExportPID3[i-1] || ExportGID3[i]!=ExportGID3[i-1]){
      ExportPID3[j] = ExportPID3[i];
      ExportGID3[j] = ExportGID3[i];
      j++;
    }
  }
  ExportPID3.resize(j);
  ExportLID3.resize(j);
  total_length3=j;

  /*  printf("[%d] Type 3 UNIQ  = ",MyComm.MyPID());
  for(i=0; i<total_length3; i++)
    printf("(--,%2d,%2d) ",ExportGID3[i],ExportPID3[i]);
  printf("\n");
  fflush(stdout);*/


  
  // Now index down to LIDs   
  for(i=0; i<total_length3; i++) {
    ExportLID3[i]=DomainMap.LID(ExportGID3[i]);
    if(ExportLID3[i] < 0) throw std::runtime_error("LightweightCrsMatrix:MakeExportLists invalid LID");    
  }
    
  /*  printf("[%d] Type 3 FINAL = ",MyComm.MyPID());
  for(i=0; i<total_length3; i++)
    printf("(%2d,%2d,%2d) ",ExportLID3[i],ExportGID3[i],ExportPID3[i]);
  printf("\n");
  fflush(stdout);*/
 
  return total_length3;
}

//=========================================================================
template<typename ImportType, typename int_type>
int build_type2_exports(const Epetra_CrsMatrix & SourceMatrix, ImportType & MyImporter, std::vector<int> &ExportLID2, std::vector<int> &ExportPID2){
  int total_length2=0;
#ifdef HAVE_MPI
  int i,j;
  const Epetra_Import *SourceImporter= SourceMatrix.Importer();

  int    *rowptr, *colind;
  double *vals;
  EPETRA_CHK_ERR(SourceMatrix.ExtractCrsDataPointers(rowptr,colind,vals));

  // Things related to messages I am sending in forward mode (MyImporter)
  int NumExportIDs                      = MyImporter.NumExportIDs();
  const int* ExportLIDs                 = MyImporter.ExportLIDs();
  const int* ExportPIDs                 = MyImporter.ExportPIDs();
  if(NumExportIDs==0) return 0;

  Epetra_Distributor& Distor            = MyImporter.Distributor();
  const Epetra_MpiDistributor * MDistor = dynamic_cast<Epetra_MpiDistributor*>(&Distor);

  // Assume I own all the cols, then flag any cols I don't own
  // This allows us to avoid LID calls later...
  std::vector<bool> IsOwned(SourceMatrix.NumMyCols(),true);
  if(SourceImporter) {
    const int * RemoteLIDs = SourceImporter->RemoteLIDs();
    // Now flag the cols I don't own
    for(i=0; i<SourceImporter->NumRemoteIDs(); i++) 
      IsOwned[RemoteLIDs[i]]=false;
  }

  // Status vector 
  std::vector<int> SentTo(SourceMatrix.NumMyCols(),-1);

  // Initial allocation: NumUnknowsSent * Max row size (guaranteed to be too large)
  for(i=0,total_length2=0; i<MDistor->NumSends(); i++) total_length2+= MDistor->LengthsTo()[i] * SourceMatrix.MaxNumEntries();
  std::vector<int_type> ExportGID2(total_length2);

  ExportLID2.resize(total_length2);
  ExportPID2.resize(total_length2);

  int current=0, last_start=0, last_pid=ExportPIDs[0];
  for(i=0; i<NumExportIDs; i++){
    // For each row I have to send via MyImporter...
    int row=ExportLIDs[i];
    int pid=ExportPIDs[i];

    if(i!=0 && pid>last_pid) {
      // We have a new PID, so lets finish up the current one      
      if(current!=last_start){
        int *lids = &ExportLID2[last_start];
  Epetra_Util::Sort(true,current-last_start,&ExportGID2[last_start],0,0,1,&lids,0,0);
  // Note: we don't need to sort the ExportPIDs since they're the same since last_start
      }
      // Reset the list
      last_pid=pid;
      last_start=current;         
    }
    else if(pid < last_pid) {
      throw std::runtime_error("build_type2_exports: ExportPIDs are not sorted!");
    }

    for(j=rowptr[row]; j<rowptr[row+1]; j++) {
      // For each column in that row...      
      int col=colind[j];
      if(IsOwned[col] && SentTo[col]!=pid){
  // We haven't added this guy to the list yet.
  if(current>= total_length2) throw std::runtime_error("build_type2_exports: More export ids than I thought!");
  SentTo[col]         = pid;
  ExportGID2[current] = (int_type) SourceMatrix.GCID64(col);
  ExportLID2[current] = SourceMatrix.DomainMap().LID(ExportGID2[current]);
  ExportPID2[current] = pid;
  current++;
      }
    }
  }//end main loop

  // Final Sort
  int *lids = ExportLID2.size() > (std::size_t) last_start ? &ExportLID2[last_start] : 0;
  Epetra_Util::Sort(true,current-last_start,ExportGID2.size() > (std::size_t) last_start ? &ExportGID2[last_start] : 0,0,0,1,&lids,0,0);
  // Note: we don't need to sort the ExportPIDs since they're the same since last_start

  total_length2=current;
  ExportLID2.resize(total_length2);
  ExportPID2.resize(total_length2);
#endif
  return total_length2;
}

//=========================================================================
template<typename int_type>
void build_type1_exports_sort(std::vector<int> &ExportLID1, std::vector<int> &ExportPID1, std::vector<int_type>& ExportGID1, int total_length1);

template<>
void build_type1_exports_sort<int>(std::vector<int> &ExportLID1, std::vector<int> &ExportPID1, std::vector<int>& ExportGID1, int total_length1){
  int * companion[2] = {&ExportLID1[0],&ExportGID1[0]};
  Epetra_Util::Sort(true,total_length1,&ExportPID1[0],0,0,2,&companion[0],0,0);
}

template<>
void build_type1_exports_sort<long long>(std::vector<int> &ExportLID1, std::vector<int> &ExportPID1, std::vector<long long>& ExportGID1, int total_length1){
  int * companion = &ExportLID1[0];
  long long * companion64 = &ExportGID1[0];
  Epetra_Util::Sort(true,total_length1,&ExportPID1[0],0,0,1,&companion,1,&companion64);
}

template<typename int_type>
int build_type1_exports(const Epetra_Import * Importer1, std::vector<int> &ExportLID1, std::vector<int> &ExportPID1){
  int i, total_length1=0;
  if(!Importer1) return 0;
  total_length1 = Importer1->NumSend();
  if(total_length1==0) return 0;

  std::vector<int_type> ExportGID1(total_length1);
  ExportLID1.resize(total_length1);
  ExportPID1.resize(total_length1);
  const int * ExportLID1Base = Importer1->ExportLIDs();
  const int * ExportPID1Base = Importer1->ExportPIDs();

  for(i=0; i<total_length1; i++){
    ExportLID1[i] = ExportLID1Base[i];
    ExportPID1[i] = ExportPID1Base[i];
    ExportGID1[i] = (int_type) Importer1->SourceMap().GID64(ExportLID1Base[i]);
  }

  // Sort (ala Epetra_CrsGraph)
  build_type1_exports_sort<int_type>(ExportLID1, ExportPID1, ExportGID1, total_length1);

  int StartCurrent, StartNext;
  StartCurrent = 0; StartNext = 1;
  while ( StartNext < total_length1 ) {
    if(ExportPID1[StartNext] == ExportPID1[StartNext-1]) StartNext++;
    else {
      int *new_companion = {&ExportLID1[StartCurrent]};
      Epetra_Util::Sort(true,StartNext-StartCurrent, &(ExportGID1[StartCurrent]),0,0,1,&new_companion, 0, 0);
      StartCurrent = StartNext; StartNext++;
    }
  }
  int *new_companion = {&ExportLID1[StartCurrent]};
  Epetra_Util::Sort(true,StartNext-StartCurrent, &(ExportGID1[StartCurrent]),0,0,1,&new_companion, 0, 0);
  return total_length1;
}

//=========================================================================
template<typename ImportType, typename int_type>
int LightweightCrsMatrix::MakeExportLists(const Epetra_CrsMatrix & SourceMatrix, ImportType & Importer2,
            std::vector<int> &ReverseRecvSizes, const int_type *ReverseRecvBuffer,
            std::vector<int> & ExportPIDs, std::vector<int> & ExportLIDs) {
#ifdef HAVE_MPI
  int MyPID = SourceMatrix.Comm().MyPID();

  // This could (legitimately) be zero, in which case we don't have any ReverseRecvs either.
  const Epetra_Import *Importer1= SourceMatrix.Importer();

  // So for each entry in the DomainMap, I have to answer the question: Do I need to send this to anybody?  And if so, to whom?
  //
  // This information comes from three sources:
  // 1) IDs in my DomainMap that are in someone else's ColMap (e.g. SourceMatrix.Importer()).
  // 2) IDs that I own that I sent to another proc in the Forward communication round (e.g. RowImporter).
  // 3) IDs that someone else sent on during the Forward round (and they told me about duing the reverse round).
  //
  // Any of these could legitimately be null.
  Epetra_MpiDistributor * Distor1 = (Importer1)?(dynamic_cast<Epetra_MpiDistributor*>(&Importer1->Distributor())):0;

  int Nsend1 = (Distor1)?(Distor1->NumSends()):0; // Also the number of messages we'll need to parse through in build_type3_exports

  std::vector<int> ExportPID3;
  std::vector<int> ExportLID3;

  std::vector<int> ExportPID2;
  std::vector<int> ExportLID2;

  std::vector<int> ExportPID1;
  std::vector<int> ExportLID1;

  // Build (sorted) ExportLID / ExportGID list for Type
  int Len1=build_type1_exports<int_type>(Importer1, ExportLID1, ExportPID1);
  int Len2=build_type2_exports<ImportType, int_type>(SourceMatrix, Importer2, ExportLID2, ExportPID2);
  int Len3=build_type3_exports(MyPID,Nsend1,DomainMap_,ReverseRecvSizes, ReverseRecvBuffer, ExportLID3, ExportPID3);

  // Since everything should now be sorted correctly, we can do a streaming merge of the three Export lists...
#ifdef HAVE_EPETRAEXT_DEBUG
  {
    int i;
    // Now we sanity check the 1 & 2 lists
    bool test_passed=true;
    for(i=1; i<Len1; i++) {
      if(ExportPID1[i] < ExportPID1[i-1] || (ExportPID1[i] == ExportPID1[i-1] && DomainMap_.GID(ExportLID1[i]) < DomainMap_.GID(ExportLID1[i-1])))
  test_passed=false;
    }
    SourceMatrix.Comm().Barrier();
    if(!test_passed) {
      printf("[%d] Type1 ERRORS  = ",SourceMatrix.Comm().MyPID());
      for(int i=0; i<Len1; i++)
  printf("(%2d,%2d,%2d) ",ExportLID1[i],DomainMap_.GID(ExportLID1[i]),ExportPID1[i]);
      printf("\n");
      fflush(stdout);      
      throw std::runtime_error("Importer1 fails the sanity test");      
    }

    for(i=1; i<Len2; i++) {
      if(ExportPID2[i] < ExportPID2[i-1]  || (ExportPID2[i] == ExportPID2[i-1] && DomainMap_.GID(ExportLID2[i]) < DomainMap_.GID(ExportLID2[i-1])))
  test_passed=false;
    }

    SourceMatrix.Comm().Barrier();
    if(!test_passed) {
      printf("[%d] Type2 ERRORS  = ",SourceMatrix.Comm().MyPID());
      for(int i=0; i<Len2; i++)
  printf("(%2d,%2d,%2d) ",ExportLID2[i],DomainMap_.GID(ExportLID2[i]),ExportPID2[i]);
      printf("\n");
      fflush(stdout);      
      throw std::runtime_error("Importer2 fails the sanity test");      
    }

    for(i=1; i<Len3; i++) {
      if(ExportPID3[i] < ExportPID3[i-1]  || (ExportPID3[i] == ExportPID3[i-1] && DomainMap_.GID(ExportLID3[i]) < DomainMap_.GID(ExportLID3[i-1])))
  test_passed=false;
    }

    SourceMatrix.Comm().Barrier();
    if(!test_passed) {
      printf("[%d] Type3 ERRORS  = ",SourceMatrix.Comm().MyPID());
      for(int i=0; i<Len3; i++)
  printf("(%2d,%2d,%2d) ",ExportLID3[i],DomainMap_.GID(ExportLID3[i]),ExportPID3[i]);
      printf("\n");
      fflush(stdout);      
      throw std::runtime_error("Importer3 fails the sanity test");      
    }


  }
#endif

  if(Importer1 && !Importer1->SourceMap().SameAs(DomainMap_))
    throw std::runtime_error("ERROR: Map Mismatch Importer1");

  if(!Importer2.SourceMap().SameAs(SourceMatrix.RowMap()))
    throw std::runtime_error("ERROR: Map Mismatch Importer2");

  int_type InfGID = std::numeric_limits<int_type>::max();
  int InfPID = INT_MAX;

  int i1=0, i2=0, i3=0, current=0;

  int MyLen=Len1+Len2+Len3;  
  ExportLIDs.resize(MyLen);
  ExportPIDs.resize(MyLen);

  while(i1 < Len1 || i2 < Len2 || i3 < Len3){
    int PID1 = (i1<Len1)?(ExportPID1[i1]):InfPID;
    int PID2 = (i2<Len2)?(ExportPID2[i2]):InfPID;
    int PID3 = (i3<Len3)?(ExportPID3[i3]):InfPID;

    int_type GID1 = (i1<Len1)?((int_type) DomainMap_.GID64(ExportLID1[i1])):InfGID;
    int_type GID2 = (i2<Len2)?((int_type) DomainMap_.GID64(ExportLID2[i2])):InfGID;
    int_type GID3 = (i3<Len3)?((int_type) DomainMap_.GID64(ExportLID3[i3])):InfGID;

    int MIN_PID = MIN3(PID1,PID2,PID3);
    int_type MIN_GID = MIN3( ((PID1==MIN_PID)?GID1:InfGID), ((PID2==MIN_PID)?GID2:InfGID), ((PID3==MIN_PID)?GID3:InfGID));
    bool added_entry=false;

    // Case 1: Add off list 1   
    if(PID1 == MIN_PID && GID1 == MIN_GID){
      ExportLIDs[current] = ExportLID1[i1];
      ExportPIDs[current] = ExportPID1[i1];
      current++;
      i1++;
      added_entry=true;
    }

    // Case 2: Add off list 2
    if(PID2 == MIN_PID && GID2 == MIN_GID){
      if(!added_entry) {
  ExportLIDs[current] = ExportLID2[i2];
  ExportPIDs[current] = ExportPID2[i2];
  current++;
  added_entry=true;
      }
      i2++; 
    }

    // Case 3: Add off list 3
    if(PID3 == MIN_PID && GID3 == MIN_GID){
      if(!added_entry) {
  ExportLIDs[current] = ExportLID3[i3];
  ExportPIDs[current] = ExportPID3[i3];
  current++;
      }
      i3++; 
    }
  }// end while
  if(current!=MyLen) {
    ExportLIDs.resize(current);
    ExportPIDs.resize(current);
  }
#endif
  return 0;
}

//=========================================================================
template<typename ImportType, typename int_type>
void LightweightCrsMatrix::Construct(const Epetra_CrsMatrix & SourceMatrix, ImportType & RowImporter)
{  
  // Do we need to use long long for GCIDs?

#ifdef ENABLE_MMM_TIMINGS
  using Teuchos::TimeMonitor;
  Teuchos::RCP<Teuchos::TimeMonitor> MM = Teuchos::rcp(new TimeMonitor(*TimeMonitor::getNewTimer("EpetraExt: LWCRS C-1")));
#endif

  // Fused constructor, import & FillComplete
  int rv=0;
  int N;
  if(use_lw) N = RowMapLW_->NumMyElements();
  else N = RowMapEP_->NumMyElements();

  int MyPID = SourceMatrix.Comm().MyPID();

#ifdef HAVE_MPI
  std::vector<int> ReverseSendSizes;
  std::vector<int_type> ReverseSendBuffer;
  std::vector<int> ReverseRecvSizes;
  int_type * ReverseRecvBuffer=0;
#endif

  bool communication_needed = RowImporter.SourceMap().DistributedGlobal();

  // The basic algorithm here is:
  // 1) Call Distor.Do to handle the import.
  // 2) Copy all the Imported and Copy/Permuted data into the raw Epetra_CrsMatrix / Epetra_CrsGraphData pointers, still using GIDs.
  // 3) Call an optimized version of MakeColMap that avoids the Directory lookups (since the importer knows who owns all the gids) AND
  //    reindexes to LIDs.

  // Sanity Check
  if (!SourceMatrix.RowMap().SameAs(RowImporter.SourceMap())) 
    throw "LightweightCrsMatrix: Fused copy constructor requires Importer.SourceMap() to match SourceMatrix.RowMap()";

  // Get information from the Importer
  int NumSameIDs             = RowImporter.NumSameIDs();
  int NumPermuteIDs          = RowImporter.NumPermuteIDs();
  int NumRemoteIDs           = RowImporter.NumRemoteIDs();
  int NumExportIDs           = RowImporter.NumExportIDs();
  int* ExportLIDs            = RowImporter.ExportLIDs();
  int* RemoteLIDs            = RowImporter.RemoteLIDs();
  int* PermuteToLIDs         = RowImporter.PermuteToLIDs();
  int* PermuteFromLIDs       = RowImporter.PermuteFromLIDs();

#ifdef HAVE_MPI
  Epetra_Distributor& Distor            = RowImporter.Distributor();
  const Epetra_MpiComm * MpiComm        = dynamic_cast<const Epetra_MpiComm*>(&SourceMatrix.Comm());
  const Epetra_MpiDistributor * MDistor = dynamic_cast<Epetra_MpiDistributor*>(&Distor);
#endif

  // Allocate memory
  rowptr_.resize(N+1);


  // Owning PIDs
  std::vector<int> SourcePids;
  std::vector<int> TargetPids;


  /***************************************************/
  /***** 1) From Epetra_DistObject::DoTransfer() *****/
  /***************************************************/
  //  rv=SourceMatrix.CheckSizes(SourceMatrix);

  // NTS: Add CheckSizes stuff here.
  if(rv) throw "LightweightCrsMatrix: Fused copy constructor failed in CheckSizes()";
  
  // Buffers & Other Relevant Info
  char* Exports_  = 0;
  char* Imports_  = 0;
  int LenImports_ =0;
  int LenExports_ = 0;
  int *Sizes_     = 0;

  int SizeOfPacket; 
  bool VarSizes = false;
  if( NumExportIDs > 0) {
    Sizes_ = new int[NumExportIDs];
  }
  

  // Get the owning PIDs
  const Epetra_Import *MyImporter= SourceMatrix.Importer();
  if(MyImporter) Epetra_Util::GetPids(*MyImporter,SourcePids,false);
  else {
    SourcePids.resize(SourceMatrix.ColMap().NumMyElements());
    SourcePids.assign(SourceMatrix.ColMap().NumMyElements(),SourceMatrix.Comm().MyPID());
  }
  
  // Pack & Prepare w/ owning PIDs
  rv=Epetra_Import_Util::PackAndPrepareWithOwningPIDs(SourceMatrix,
                  NumExportIDs,ExportLIDs,
                  LenExports_,Exports_,SizeOfPacket,
                  Sizes_,VarSizes,SourcePids);
  if(rv) throw "LightweightCrsMatrix: Fused copy constructor failed in PackAndPrepare()";

  if (communication_needed) {
#ifdef HAVE_MPI 
    // Do the exchange of remote data
    int i,curr_pid;
    const int * ExportPIDs = RowImporter.ExportPIDs();

    // Use the fact that the export procs are sorted to avoid building a hash table.
    // NOTE: The +1's on the message size lists are to avoid std::vector problems if a proc has no sends or recvs. 
    std::vector<int> SendSizes(MDistor->NumSends()+1,0);
    for(i=0, curr_pid=0; i<NumExportIDs; i++) { 
      if(i>0 &&  ExportPIDs[i] > ExportPIDs[i-1]) curr_pid++;
      SendSizes[curr_pid] +=Sizes_[i];

      // sanity check
      if(i>0 &&  ExportPIDs[i] < ExportPIDs[i-1]) throw "ExportPIDs not sorted";
    }

    std::vector<int> RecvSizes(MDistor->NumReceives()+1);
    int msg_tag=MpiComm->GetMpiTag();
    boundary_exchange_varsize<char>(*MpiComm,MPI_CHAR,MDistor->NumSends(),MDistor->ProcsTo(),SendSizes.size() ? &SendSizes[0] : 0,Exports_,
            MDistor->NumReceives(),MDistor->ProcsFrom(),RecvSizes.size() ? &RecvSizes[0] : 0,Imports_,SizeOfPacket,msg_tag);

    // If the  source matrix doesn't have an importer, then nobody sent data belonging to me in the forward round.
    if(SourceMatrix.Importer()) {
      Epetra_Import* SourceImporter=const_cast<Epetra_Import*>(SourceMatrix.Importer());
      const Epetra_MpiDistributor * MyDistor = dynamic_cast<Epetra_MpiDistributor*>(&SourceImporter->Distributor());

      // Setup the reverse communication
      // Note: Buffer pairs are in (PID,GID) order
      PackAndPrepareReverseComm<ImportType, int_type>(SourceMatrix,RowImporter,ReverseSendSizes,ReverseSendBuffer);
      
      // Do the reverse communication
      // NOTE: Make the vector one too large to avoid std::vector errors
      ReverseRecvSizes.resize(MyDistor->NumSends()+1);
      int msg_tag=MpiComm->GetMpiTag();
    MPI_Datatype data_type = sizeof(int_type) == 4 ? MPI_INT : MPI_LONG_LONG;
      boundary_exchange_varsize<int_type>(*MpiComm,data_type,MyDistor->NumReceives(),MyDistor->ProcsFrom(),ReverseSendSizes.size() ? &ReverseSendSizes[0] : 0, ReverseSendBuffer.size() ? &ReverseSendBuffer[0] : 0,
              MyDistor->NumSends(),MyDistor->ProcsTo(),ReverseRecvSizes.size() ? &ReverseRecvSizes[0] : 0,ReverseRecvBuffer,1,msg_tag);      
    }
#endif
  }

  if(rv) throw "LightweightCrsMatrix: Fused copy constructor failed in Distor.Do";

  /*********************************************************************/
  /**** 2) Copy all of the Same/Permute/Remote data into CSR_arrays ****/
  /*********************************************************************/
#ifdef ENABLE_MMM_TIMINGS
  MM = Teuchos::rcp(new TimeMonitor(*TimeMonitor::getNewTimer("EpetraExt: LWCRS C-2")));
#endif

  // Count nnz
  int mynnz = Epetra_Import_Util::UnpackWithOwningPIDsCount(SourceMatrix,NumSameIDs,NumRemoteIDs,RemoteLIDs,NumPermuteIDs,PermuteToLIDs,PermuteFromLIDs,LenImports_,Imports_);
  // Presume the rowptr_ is the right size
  // Allocate colind_ & vals_ arrays
  colind_.resize(mynnz);
#ifndef EPETRA_NO_64BIT_GLOBAL_INDICES
  if(sizeof(int_type) == sizeof(long long))
    colind_LL_.resize(mynnz);
#endif
  vals_.resize(mynnz);

  // Reset the Source PIDs (now with -1 rule)
  if(MyImporter) Epetra_Util::GetPids(*MyImporter,SourcePids,true);
  else {
    SourcePids.assign(SourceMatrix.ColMap().NumMyElements(),-1);
  }
   
  // Unpack into arrays
  int * myrowptr  = rowptr_.size() ? & rowptr_[0] : 0;
  double * myvals = vals_.size()   ? & vals_[0] : 0;
#ifndef EPETRA_NO_32BIT_GLOBAL_INDICES
  if(sizeof(int_type) == sizeof(int)) {
    int * mycolind  = colind_.size() ? & colind_[0] : 0;
    Epetra_Import_Util::UnpackAndCombineIntoCrsArrays(SourceMatrix,NumSameIDs,NumRemoteIDs,RemoteLIDs,NumPermuteIDs,PermuteToLIDs,PermuteFromLIDs,LenImports_,Imports_,N,mynnz,MyPID,myrowptr,mycolind,myvals,SourcePids,TargetPids);
  }
  else
#endif
#ifndef EPETRA_NO_64BIT_GLOBAL_INDICES
  if(sizeof(int_type) == sizeof(long long)) {
    long long * mycolind  = colind_LL_.size() ? & colind_LL_[0] : 0;
    Epetra_Import_Util::UnpackAndCombineIntoCrsArrays(SourceMatrix,NumSameIDs,NumRemoteIDs,RemoteLIDs,NumPermuteIDs,PermuteToLIDs,PermuteFromLIDs,LenImports_,Imports_,N,mynnz,MyPID,myrowptr,mycolind,myvals,SourcePids,TargetPids);
  }
  else
#endif
  throw "EpetraExt::LightweightCrsMatrix::Construct: sizeof(int_type) error.";

  /**************************************************************/
  /**** 3) Call Optimized MakeColMap w/ no Directory Lookups ****/
  /**************************************************************/
#ifdef ENABLE_MMM_TIMINGS
  MM = Teuchos::rcp(new TimeMonitor(*TimeMonitor::getNewTimer("EpetraExt: LWCRS C-3")));
#endif

  //Call an optimized version of MakeColMap that avoids the Directory lookups (since the importer knows who owns all the gids).
  MakeColMapAndReindex<int_type>(TargetPids,getcolind<int_type>());

  /********************************************/
  /**** 4) Make Export Lists for Import    ****/
  /********************************************/
#ifdef HAVE_MPI
  MakeExportLists<ImportType, int_type>(SourceMatrix,RowImporter,ReverseRecvSizes,ReverseRecvBuffer,ExportPIDs_,ExportLIDs_);
#endif 

  /********************************************/
  /**** 5) Call sort the entries           ****/
  /********************************************/
  // NOTE: If we have no entries the &blah[0] will cause the STL to die in debug mode
#ifdef ENABLE_MMM_TIMINGS
  MM = Teuchos::rcp(new TimeMonitor(*TimeMonitor::getNewTimer("EpetraExt: LWCRS C-4")));
#endif
  if(N>0) Epetra_Util::SortCrsEntries(N, &rowptr_[0], colind_.size() ? &colind_[0] : 0, vals_.size() ? &vals_[0] : 0);

  /********************************************/
  /**** 6) Cleanup                         ****/
  /********************************************/
#ifdef ENABLE_MMM_TIMINGS
  MM = Teuchos::rcp(new TimeMonitor(*TimeMonitor::getNewTimer("EpetraExt: LWCRS C-5")));
#endif

#ifdef HAVE_MPI
  delete [] ReverseRecvBuffer;
#endif

  delete [] Exports_;
  delete [] Imports_;
  delete [] Sizes_;

 }// end fused copy constructor




//=========================================================================
LightweightCrsMatrix::LightweightCrsMatrix(const Epetra_CrsMatrix & SourceMatrix, RemoteOnlyImport & RowImporter):
  use_lw(true),
  RowMapLW_(0),
  RowMapEP_(0),
  DomainMap_(SourceMatrix.DomainMap())
{ 
#ifdef ENABLE_MMM_TIMINGS
  using Teuchos::TimeMonitor;
  Teuchos::RCP<Teuchos::TimeMonitor> MM = Teuchos::rcp(new TimeMonitor(*TimeMonitor::getNewTimer("EpetraExt: LWCRS Total")));
#endif

  RowMapLW_= new LightweightMap(RowImporter.TargetMap());
   
#ifndef EPETRA_NO_32BIT_GLOBAL_INDICES
  if(SourceMatrix.RowMatrixRowMap().GlobalIndicesInt()) {
    Construct<RemoteOnlyImport, int>(SourceMatrix,RowImporter);
  }
  else
#endif
#ifndef EPETRA_NO_64BIT_GLOBAL_INDICES
  if(SourceMatrix.RowMatrixRowMap().GlobalIndicesLongLong()) {
    Construct<RemoteOnlyImport, long long>(SourceMatrix,RowImporter);
  }
  else
#endif
    throw "EpetraExt::LightweightCrsMatrix: ERROR, GlobalIndices type unknown.";

}


//=========================================================================
LightweightCrsMatrix::LightweightCrsMatrix(const Epetra_CrsMatrix & SourceMatrix, Epetra_Import & RowImporter):
  use_lw(false),
  RowMapLW_(0),
  RowMapEP_(0),
  DomainMap_(SourceMatrix.DomainMap())
{
  RowMapEP_= new Epetra_BlockMap(RowImporter.TargetMap());
#ifndef EPETRA_NO_32BIT_GLOBAL_INDICES
  if(SourceMatrix.RowMatrixRowMap().GlobalIndicesInt()) {
    Construct<Epetra_Import, int>(SourceMatrix,RowImporter);
  }
  else
#endif
#ifndef EPETRA_NO_64BIT_GLOBAL_INDICES
  if(SourceMatrix.RowMatrixRowMap().GlobalIndicesLongLong()) {
    Construct<Epetra_Import, long long>(SourceMatrix,RowImporter);
  }
  else
#endif
    throw "EpetraExt::LightweightCrsMatrix: ERROR, GlobalIndices type unknown.";
}


LightweightCrsMatrix::~LightweightCrsMatrix(){
  delete RowMapLW_;
  delete RowMapEP_;
}


}//namespace EpetraExt

#ifndef EPETRA_NO_32BIT_GLOBAL_INDICES
template class EpetraExt::CrsWrapper_GraphBuilder<int>;
#endif

#ifndef EPETRA_NO_64BIT_GLOBAL_INDICES
template class EpetraExt::CrsWrapper_GraphBuilder<long long>;
#endif