HypreParMatrix.cpp

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// Copyright (c) 2010, Lawrence Livermore National Security, LLC. Produced at
// the Lawrence Livermore National Laboratory. LLNL-CODE-443211. All Rights
// reserved. See file COPYRIGHT for details.
//
// This file is part of the MFEM library. For more information and source code
// availability see http://mfem.org.
//
// MFEM is free software; you can redistribute it and/or modify it under the
// terms of the GNU Lesser General Public License (as published by the Free
// Software Foundation) version 2.1 dated February 1999.

#include "HypreParVector.hpp"
#include "HypreParMatrix.hpp"

#ifdef MOAB_HAVE_MPI

#include "hypre_parcsr.hpp"

#include <fstream>
#include <iostream>
#include <cmath>
#include <cstdlib>
#include <cassert>

using namespace std;

#define MOAB_DEBUG

namespace moab
{
#define moab_hypre_assert( a, b ) \
    {                             \
    }
#define moab_hypre_assert_t( a, b )                         \
    {                                                       \
        if( !a )                                            \
        {                                                   \
            std::cout << "HYPRE Error: " << b << std::endl; \
            exit( -1 );                                     \
        }                                                   \
    }

template < typename TargetT, typename SourceT >
static TargetT* DuplicateAs( const SourceT* array, int size, bool cplusplus = true )
{
    TargetT* target_array = cplusplus ? new TargetT[size]
                                      /*     */
                                      : hypre_TAlloc( TargetT, size );

    for( int i = 0; i < size; i++ )
    {
        target_array[i] = array[i];
    }

    return target_array;
}

void HypreParMatrix::Init()
{
    A           = NULL;
    A_parcsr    = NULL;
    ParCSROwner = 1;
}

HypreParMatrix::HypreParMatrix( moab::ParallelComm* p_comm ) : pcomm( p_comm )
{
    Init();
    height = width = 0;
}

// Square block-diagonal constructor
HypreParMatrix::HypreParMatrix( moab::ParallelComm* p_comm,
                                HYPRE_Int glob_size,
                                HYPRE_Int* row_starts,
                                HYPRE_Int nnz_pr )
    : pcomm( p_comm )
{
    Init();
    resize( glob_size, row_starts, nnz_pr );
}

void HypreParMatrix::resize( HYPRE_Int glob_size,
                             HYPRE_Int* row_starts,
                             HYPRE_Int nnz_pr_diag,
                             HYPRE_Int nnz_pr_offdiag )
{
    /* Create the matrix.
        Note that this is a square matrix, so we indicate the row partition
        size twice (since number of rows = number of cols) */
    HYPRE_IJMatrixCreate( pcomm->comm(), row_starts[0], row_starts[1], row_starts[0], row_starts[1], &A );
    /* Choose a parallel csr format storage (see the User's Manual) */
    HYPRE_IJMatrixSetObjectType( A, HYPRE_PARCSR );

    int locsize = row_starts[1] - row_starts[0] + 1;
    int num_procs, rank;
    MPI_Comm_size( pcomm->comm(), &num_procs );
    MPI_Comm_rank( pcomm->comm(), &rank );

    if( nnz_pr_diag != 0 || nnz_pr_offdiag != 0 )
    {
        if( num_procs > 1 )
        {
            std::vector< HYPRE_Int > m_nnz_pr_diag( locsize, nnz_pr_diag );
            std::vector< HYPRE_Int > m_onz_pr_diag( locsize, nnz_pr_offdiag );
            HYPRE_IJMatrixSetDiagOffdSizes( A, &m_nnz_pr_diag[0], &m_onz_pr_diag[0] );
        }
        else
        {
            std::vector< HYPRE_Int > m_nnz_pr_diag( locsize, nnz_pr_diag );
            HYPRE_IJMatrixSetRowSizes( A, &m_nnz_pr_diag[0] );
        }
    }

    /* Initialize before setting coefficients */
    HYPRE_IJMatrixInitialize( A );
    /* Get the parcsr matrix object to use */
    HYPRE_IJMatrixGetObject( A, (void**)&A_parcsr );

    /* define an interpreter for the ParCSR interface */
    HYPRE_MatvecFunctions matvec_fn;
    interpreter = hypre_CTAlloc( mv_InterfaceInterpreter, 1 );
    HYPRE_ParCSRSetupInterpreter( interpreter );
    HYPRE_ParCSRSetupMatvec( &matvec_fn );
    gnrows = glob_size;
    gncols = glob_size;
    height = GetNumRows();
    width  = GetNumCols();
}

void HypreParMatrix::resize( HYPRE_Int global_num_rows,
                             HYPRE_Int global_num_cols,
                             HYPRE_Int* row_starts,
                             HYPRE_Int* col_starts,
                             HYPRE_Int* nnz_pr_diag,
                             HYPRE_Int* onz_pr_diag,
                             HYPRE_Int nnz_pr_offdiag )
{
    /* Create the matrix.
        Note that this is a square matrix, so we indicate the row partition
        size twice (since number of rows = number of cols) */
    HYPRE_IJMatrixCreate( pcomm->comm(), row_starts[0], row_starts[1], col_starts[0], col_starts[1], &A );
    /* Choose a parallel csr format storage (see the User's Manual) */
    HYPRE_IJMatrixSetObjectType( A, HYPRE_PARCSR );

    int num_procs;
    MPI_Comm_size( pcomm->comm(), &num_procs );

    /* Set the matrix pre-allocation data */
    if( num_procs > 1 )
    {
        if( nnz_pr_diag == NULL && onz_pr_diag == NULL )
        {
            std::cout << "Parameter nnz_pr_diag and onz_pr_diag cannot be NULL.\n";
            moab_hypre_assert_t( nnz_pr_diag, true );
        }

        HYPRE_IJMatrixSetDiagOffdSizes( A, nnz_pr_diag, onz_pr_diag );
    }
    else
    {
        HYPRE_IJMatrixSetRowSizes( A, nnz_pr_diag );
    }

    if( nnz_pr_offdiag )
    {
        HYPRE_IJMatrixSetMaxOffProcElmts( A, nnz_pr_offdiag );
    }

    /* Initialize before setting coefficients */
    HYPRE_IJMatrixInitialize( A );
    /* Get the parcsr matrix object to use */
    HYPRE_IJMatrixGetObject( A, (void**)&A_parcsr );

    /* define an interpreter for the ParCSR interface */
    HYPRE_MatvecFunctions matvec_fn;
    interpreter = hypre_CTAlloc( mv_InterfaceInterpreter, 1 );
    HYPRE_ParCSRSetupInterpreter( interpreter );
    HYPRE_ParCSRSetupMatvec( &matvec_fn );
    gnrows = global_num_rows;
    gncols = global_num_cols;
    height = GetNumRows();
    width  = GetNumCols();
}

// Rectangular block-diagonal constructor
HypreParMatrix::HypreParMatrix( moab::ParallelComm* p_comm,
                                HYPRE_Int global_num_rows,
                                HYPRE_Int global_num_cols,
                                HYPRE_Int* row_starts,
                                HYPRE_Int* col_starts,
                                HYPRE_Int nnz_pr_diag,
                                HYPRE_Int onz_pr_diag,
                                HYPRE_Int nnz_pr_offdiag )
    : pcomm( p_comm )
{
    Init();
    std::vector< HYPRE_Int > m_nnz_pr_diag( row_starts[1] - row_starts[0], nnz_pr_diag );
    std::vector< HYPRE_Int > m_onz_pr_diag( row_starts[1] - row_starts[0], onz_pr_diag );
    resize( global_num_rows, global_num_cols, row_starts, col_starts, &m_nnz_pr_diag[0], &m_onz_pr_diag[0],
            nnz_pr_offdiag );
}

void HypreParMatrix::MakeRef( const HypreParMatrix& master )
{
    Destroy();
    Init();
    A           = master.A;
    A_parcsr    = master.A_parcsr;
    ParCSROwner = 0;
    height      = master.GetNumRows();
    width       = master.GetNumCols();
}

HYPRE_IJMatrix HypreParMatrix::StealData()
{
    // Only safe when (diagOwner == -1 && offdOwner == -1 && colMapOwner == -1)
    // Otherwise, there may be memory leaks or hypre may destroy arrays allocated
    // with operator new.
    moab_hypre_assert( diagOwner == -1 && offdOwner == -1 && colMapOwner == -1, "" );
    moab_hypre_assert( ParCSROwner, "" );
    HYPRE_IJMatrix R = A;
    A                = NULL;
    ParCSROwner      = 0;
    Destroy();
    Init();
    return R;
}

void HypreParMatrix::StealData( HypreParMatrix& X )
{
    // Only safe when (diagOwner == -1 && offdOwner == -1 && colMapOwner == -1)
    // Otherwise, there may be memory leaks or hypre may destroy arrays allocated
    // with operator new.
    moab_hypre_assert( diagOwner == -1 && offdOwner == -1 && colMapOwner == -1, "" );
    moab_hypre_assert( ParCSROwner, "" );
    moab_hypre_assert( X.diagOwner == -1 && X.offdOwner == -1 && X.colMapOwner == -1, "" );
    moab_hypre_assert( X.ParCSROwner, "" );
    A             = X.A;
    A_parcsr      = X.A_parcsr;
    ParCSROwner   = 1;
    X.A           = NULL;
    X.A_parcsr    = NULL;
    X.ParCSROwner = 0;
    X.Destroy();
    X.Init();
}

void HypreParMatrix::GetDiag( Eigen::VectorXd& diag ) const
{
    int size = this->height;
    diag.resize( size );

    for( int j = 0; j < size; j++ )
    {
        diag( j ) = A_parcsr->diag->data[A_parcsr->diag->i[j]];
        moab_hypre_assert( A_parcsr->diag->j[A_parcsr->diag->i[j]] == j,
                           "the first entry in each row must be the diagonal one" );
    }
}

static void MakeWrapper( const hypre_CSRMatrix* mat, Eigen::SparseMatrix< double, Eigen::RowMajor >& wrapper )
{
    HYPRE_Int nr = hypre_CSRMatrixNumRows( mat );
    HYPRE_Int nc = hypre_CSRMatrixNumCols( mat );
    Eigen::SparseMatrix< double, Eigen::RowMajor > tmp( nr, nc );
    typedef Eigen::Triplet< double > T;
    HYPRE_Int nnz = hypre_CSRMatrixNumNonzeros( mat );
    int *rindx, *cindx;
    double* dindx;
#ifndef HYPRE_BIGINT
    rindx = hypre_CSRMatrixI( mat );
    cindx = hypre_CSRMatrixJ( mat );
    dindx = hypre_CSRMatrixData( mat );
#else
    rindx = DuplicateAs< int >( hypre_CSRMatrixI( mat ), nr + 1 );
    cindx = DuplicateAs< int >( hypre_CSRMatrixJ( mat ), nnz );
    dindx = hypre_CSRMatrixData( mat );
#endif
    std::vector< T > tripletList( nnz );

    for( int i = 0; i < nnz; ++i )
    {
        tripletList.push_back( T( rindx[i], cindx[i], dindx[i] ) );
    }

    tmp.setFromTriplets( tripletList.begin(), tripletList.end() );
    wrapper.swap( tmp );
}

void HypreParMatrix::GetDiag( Eigen::SparseMatrix< double, Eigen::RowMajor >& diag ) const
{
    MakeWrapper( A_parcsr->diag, diag );
}

void HypreParMatrix::GetOffd( Eigen::SparseMatrix< double, Eigen::RowMajor >& offd, HYPRE_Int*& cmap ) const
{
    MakeWrapper( A_parcsr->offd, offd );
    cmap = A_parcsr->col_map_offd;
}

// void HypreParMatrix::GetBlocks(Eigen::Array<HypreParMatrix*,Eigen::Dynamic,Eigen::Dynamic>
// &blocks,
//                                bool interleaved_rows,
//                                bool interleaved_cols) const
// {
//    int nr = blocks.rows();
//    int nc = blocks.cols();

//    hypre_ParCSRMatrix **hypre_blocks = new hypre_ParCSRMatrix*[nr * nc];
//    internal::hypre_ParCSRMatrixSplit(A, nr, nc, hypre_blocks,
//                                      interleaved_rows, interleaved_cols);

//    for (int i = 0; i < nr; i++)
//    {
//       for (int j = 0; j < nc; j++)
//       {
//          blocks[i][j] = new HypreParMatrix(hypre_blocks[i*nc + j]);
//       }
//    }

//    delete [] hypre_blocks;
// }

// HypreParMatrix * HypreParMatrix::Transpose()
// {
//    hypre_ParCSRMatrix * At;
//    hypre_ParCSRMatrixTranspose(A_parcsr, &At, 1);
//    hypre_ParCSRMatrixSetNumNonzeros(At);

//    hypre_MatvecCommPkgCreate(At);

//    return new HypreParMatrix(At);
// }

HYPRE_Int HypreParMatrix::Mult( HypreParVector& x, HypreParVector& y, double a, double b )
{
    return hypre_ParCSRMatrixMatvec( a, A_parcsr, x.x_par, b, y.x_par );
}

void HypreParMatrix::Mult( double a, const HypreParVector& x, double b, HypreParVector& y ) const
{
    hypre_ParCSRMatrixMatvec( a, A_parcsr, x.x_par, b, y.x_par );
}

void HypreParMatrix::MultTranspose( double a, const HypreParVector& x, double b, HypreParVector& y ) const
{
    hypre_ParCSRMatrixMatvecT( a, A_parcsr, y.x_par, b, x.x_par );
}

HYPRE_Int HypreParMatrix::Mult( HYPRE_ParVector x, HYPRE_ParVector y, double a, double b )
{
    return hypre_ParCSRMatrixMatvec( a, A_parcsr, (hypre_ParVector*)x, b, (hypre_ParVector*)y );
}

HYPRE_Int HypreParMatrix::MultTranspose( HypreParVector& x, HypreParVector& y, double a, double b )
{
    return hypre_ParCSRMatrixMatvecT( a, A_parcsr, x.x_par, b, y.x_par );
}

// HypreParMatrix* HypreParMatrix::LeftDiagMult(const Eigen::SparseMatrix<double, Eigen::RowMajor>
// &D,
//                                              HYPRE_Int* row_starts) const
// {
//    const bool assumed_partition = HYPRE_AssumedPartitionCheck();
//    const bool same_rows = (D.rows() == hypre_CSRMatrixNumRows(A_parcsr->diag));

//    int part_size;
//    if (assumed_partition)
//    {
//       part_size = 2;
//    }
//    else
//    {
//       MPI_Comm_size(GetComm(), &part_size);
//       part_size++;
//    }

//    HYPRE_Int global_num_rows;
//    if (same_rows)
//    {
//       row_starts = hypre_ParCSRMatrixRowStarts(A_parcsr);
//       global_num_rows = hypre_ParCSRMatrixGlobalNumRows(A_parcsr);
//    }
//    else
//    {
//       // MFEM_VERIFY(row_starts != NULL, "the number of rows in D and A is not "
//       //             "the same; row_starts must be given (not NULL)");
//       // Here, when assumed_partition is true we use row_starts[2], so
//       // row_starts must come from the GetDofOffsets/GetTrueDofOffsets methods
//       // of ParFiniteElementSpace (HYPRE's partitions have only 2 entries).
//       global_num_rows =
//          assumed_partition ? row_starts[2] : row_starts[part_size-1];
//    }

//    HYPRE_Int *col_starts = hypre_ParCSRMatrixColStarts(A_parcsr);
//    HYPRE_Int *col_map_offd;

//    // get the diag and offd blocks as SparseMatrix wrappers
//    Eigen::SparseMatrix<double, Eigen::RowMajor> A_diag, A_offd;
//    GetDiag(A_diag);
//    GetOffd(A_offd, col_map_offd);

//    // multiply the blocks with D and create a new HypreParMatrix
//    Eigen::SparseMatrix<double, Eigen::RowMajor> DA_diag = (D * A_diag);
//    Eigen::SparseMatrix<double, Eigen::RowMajor> DA_offd = (D * A_offd);

//    HypreParMatrix* DA =
//       new HypreParMatrix(GetComm(),
//                          global_num_rows, hypre_ParCSRMatrixGlobalNumCols(A),
//                          DuplicateAs<HYPRE_Int>(row_starts, part_size, false),
//                          DuplicateAs<HYPRE_Int>(col_starts, part_size, false),
//                          &DA_diag, &DA_offd,
//                          DuplicateAs<HYPRE_Int>(col_map_offd, A_offd.cols()));

//    // When HYPRE_BIGINT is defined, we want DA_{diag,offd} to delete their I and
//    // J arrays but not their data arrays; when HYPRE_BIGINT is not defined, we
//    // don't want DA_{diag,offd} to delete anything.
// // #ifndef HYPRE_BIGINT
// //    DA_diag.LoseData();
// //    DA_offd.LoseData();
// // #else
// //    DA_diag.SetDataOwner(false);
// //    DA_offd.SetDataOwner(false);
// // #endif

//    // delete DA_diag;
//    // delete DA_offd;

//    hypre_ParCSRMatrixSetRowStartsOwner(DA->A, 1);
//    hypre_ParCSRMatrixSetColStartsOwner(DA->A, 1);

//    DA->diagOwner = DA->offdOwner = 3;
//    DA->colMapOwner = 1;

//    return DA;
// }

void HypreParMatrix::ScaleRows( const Eigen::VectorXd& diag )
{
    if( hypre_CSRMatrixNumRows( A_parcsr->diag ) != hypre_CSRMatrixNumRows( A_parcsr->offd ) )
    {
        MB_SET_ERR_RET( "Row does not match" );
    }

    if( hypre_CSRMatrixNumRows( A_parcsr->diag ) != diag.size() )
    {
        MB_SET_ERR_RET( "Note the Eigen::VectorXd diag is not of compatible dimensions with A\n" );
    }

    int size           = this->height;
    double* Adiag_data = hypre_CSRMatrixData( A_parcsr->diag );
    HYPRE_Int* Adiag_i = hypre_CSRMatrixI( A_parcsr->diag );
    double* Aoffd_data = hypre_CSRMatrixData( A_parcsr->offd );
    HYPRE_Int* Aoffd_i = hypre_CSRMatrixI( A_parcsr->offd );
    double val;
    HYPRE_Int jj;

    for( int i( 0 ); i < size; ++i )
    {
        val = diag[i];

        for( jj = Adiag_i[i]; jj < Adiag_i[i + 1]; ++jj )
        {
            Adiag_data[jj] *= val;
        }

        for( jj = Aoffd_i[i]; jj < Aoffd_i[i + 1]; ++jj )
        {
            Aoffd_data[jj] *= val;
        }
    }
}

void HypreParMatrix::InvScaleRows( const Eigen::VectorXd& diag )
{
    if( hypre_CSRMatrixNumRows( A_parcsr->diag ) != hypre_CSRMatrixNumRows( A_parcsr->offd ) )
    {
        MB_SET_ERR_RET( "Row does not match" );
    }

    if( hypre_CSRMatrixNumRows( A_parcsr->diag ) != diag.size() )
    {
        MB_SET_ERR_RET( "Note the Eigen::VectorXd diag is not of compatible dimensions with A_parcsr\n" );
    }

    int size           = this->height;
    double* Adiag_data = hypre_CSRMatrixData( A_parcsr->diag );
    HYPRE_Int* Adiag_i = hypre_CSRMatrixI( A_parcsr->diag );
    double* Aoffd_data = hypre_CSRMatrixData( A_parcsr->offd );
    HYPRE_Int* Aoffd_i = hypre_CSRMatrixI( A_parcsr->offd );
    double val;
    HYPRE_Int jj;

    for( int i( 0 ); i < size; ++i )
    {
#ifdef MOAB_DEBUG

        if( 0.0 == diag( i ) )
        {
            MB_SET_ERR_RET( "HypreParMatrix::InvDiagScale : Division by 0" );
        }

#endif
        val = 1. / diag( i );

        for( jj = Adiag_i[i]; jj < Adiag_i[i + 1]; ++jj )
        {
            Adiag_data[jj] *= val;
        }

        for( jj = Aoffd_i[i]; jj < Aoffd_i[i + 1]; ++jj )
        {
            Aoffd_data[jj] *= val;
        }
    }
}

void HypreParMatrix::operator*=( double s )
{
    if( hypre_CSRMatrixNumRows( A_parcsr->diag ) != hypre_CSRMatrixNumRows( A_parcsr->offd ) )
    {
        MB_SET_ERR_RET( "Row does not match" );
    }

    HYPRE_Int size = hypre_CSRMatrixNumRows( A_parcsr->diag );
    HYPRE_Int jj;
    double* Adiag_data = hypre_CSRMatrixData( A_parcsr->diag );
    HYPRE_Int* Adiag_i = hypre_CSRMatrixI( A_parcsr->diag );

    for( jj = 0; jj < Adiag_i[size]; ++jj )
    {
        Adiag_data[jj] *= s;
    }

    double* Aoffd_data = hypre_CSRMatrixData( A_parcsr->offd );
    HYPRE_Int* Aoffd_i = hypre_CSRMatrixI( A_parcsr->offd );

    for( jj = 0; jj < Aoffd_i[size]; ++jj )
    {
        Aoffd_data[jj] *= s;
    }
}

HYPRE_Int HypreParMatrix::GetValues( const HYPRE_Int nrows,
                                     HYPRE_Int* ncols,
                                     HYPRE_Int* rows,
                                     HYPRE_Int* cols,
                                     HYPRE_Complex* values )
{
    return HYPRE_IJMatrixGetValues( A, nrows, ncols, rows, cols, values );
}

HYPRE_Int HypreParMatrix::SetValues( const HYPRE_Int nrows,
                                     HYPRE_Int* ncols,
                                     const HYPRE_Int* rows,
                                     const HYPRE_Int* cols,
                                     const HYPRE_Complex* values )
{
    return HYPRE_IJMatrixSetValues( A, nrows, ncols, rows, cols, values );
}

HYPRE_Int HypreParMatrix::AddToValues( const HYPRE_Int nrows,
                                       HYPRE_Int* ncols,
                                       const HYPRE_Int* rows,
                                       const HYPRE_Int* cols,
                                       const HYPRE_Complex* values )
{
    return HYPRE_IJMatrixAddToValues( A, nrows, ncols, rows, cols, values );
}

HYPRE_Int HypreParMatrix::verbosity( const HYPRE_Int level )
{
    return HYPRE_IJMatrixSetPrintLevel( A, level );
}

HYPRE_Int HypreParMatrix::FinalizeAssembly()
{
    return HYPRE_IJMatrixAssemble( A );
}

static void get_sorted_rows_cols( const std::vector< HYPRE_Int >& rows_cols, std::vector< HYPRE_Int >& hypre_sorted )
{
    hypre_sorted.resize( rows_cols.size() );
    std::copy( rows_cols.begin(), rows_cols.end(), hypre_sorted.begin() );
    std::sort( hypre_sorted.begin(), hypre_sorted.end() );
}

void HypreParMatrix::Threshold( double threshold )
{
    int ierr = 0;
    int num_procs;
    hypre_CSRMatrix* csr_A;
    hypre_CSRMatrix* csr_A_wo_z;
    hypre_ParCSRMatrix* parcsr_A_ptr;
    int* row_starts = NULL;
    int* col_starts = NULL;
    int row_start   = -1;
    int row_end     = -1;
    int col_start   = -1;
    int col_end     = -1;
    MPI_Comm_size( pcomm->comm(), &num_procs );
    ierr += hypre_ParCSRMatrixGetLocalRange( A_parcsr, &row_start, &row_end, &col_start, &col_end );
    row_starts   = hypre_ParCSRMatrixRowStarts( A_parcsr );
    col_starts   = hypre_ParCSRMatrixColStarts( A_parcsr );
    parcsr_A_ptr = hypre_ParCSRMatrixCreate( pcomm->comm(), row_starts[num_procs], col_starts[num_procs], row_starts,
                                             col_starts, 0, 0, 0 );
    csr_A        = hypre_MergeDiagAndOffd( A_parcsr );
    csr_A_wo_z   = hypre_CSRMatrixDeleteZeros( csr_A, threshold );

    /* hypre_CSRMatrixDeleteZeros will return a NULL pointer rather than a usable
       CSR matrix if it finds no non-zeros */
    if( csr_A_wo_z == NULL )
    {
        csr_A_wo_z = csr_A;
    }
    else
    {
        ierr += hypre_CSRMatrixDestroy( csr_A );
    }

    ierr += GenerateDiagAndOffd( csr_A_wo_z, parcsr_A_ptr, col_start, col_end );
    ierr += hypre_CSRMatrixDestroy( csr_A_wo_z );
    ierr += hypre_ParCSRMatrixDestroy( A_parcsr );
    hypre_IJMatrixObject( A ) = parcsr_A_ptr;
    /* Get the parcsr matrix object to use */
    HYPRE_IJMatrixGetObject( A, (void**)A_parcsr );
}

void HypreParMatrix::EliminateRowsCols( const std::vector< HYPRE_Int >& rows_cols,
                                        const HypreParVector& X,
                                        HypreParVector& B )
{
    std::vector< HYPRE_Int > rc_sorted;
    get_sorted_rows_cols( rows_cols, rc_sorted );
    internal::hypre_ParCSRMatrixEliminateAXB( A_parcsr, rc_sorted.size(), rc_sorted.data(), X.x_par, B.x_par );
}

HypreParMatrix* HypreParMatrix::EliminateRowsCols( const std::vector< HYPRE_Int >& rows_cols )
{
    std::vector< HYPRE_Int > rc_sorted;
    get_sorted_rows_cols( rows_cols, rc_sorted );
    hypre_ParCSRMatrix* Ae;
    internal::hypre_ParCSRMatrixEliminateAAe( A_parcsr, &Ae, rc_sorted.size(), rc_sorted.data() );
    HypreParMatrix* tmpMat            = new HypreParMatrix( pcomm, M(), N(), RowPart(), ColPart(), 0, 0 );
    hypre_IJMatrixObject( tmpMat->A ) = Ae;
    /* Get the parcsr matrix object to use */
    HYPRE_IJMatrixGetObject( tmpMat->A, (void**)tmpMat->A_parcsr );
    return tmpMat;
}

void HypreParMatrix::Print( const char* fname, HYPRE_Int offi, HYPRE_Int offj )
{
    hypre_ParCSRMatrixPrintIJ( A_parcsr, offi, offj, fname );
}

void HypreParMatrix::Read( const char* fname )
{
    Destroy();
    Init();
    HYPRE_Int base_i, base_j;
    hypre_ParCSRMatrixReadIJ( pcomm->comm(), fname, &base_i, &base_j, &A_parcsr );
    hypre_ParCSRMatrixSetNumNonzeros( A_parcsr );
    hypre_MatvecCommPkgCreate( A_parcsr );
    height = GetNumRows();
    width  = GetNumCols();
}

void HypreParMatrix::Destroy()
{
    if( interpreter )
    {
        hypre_TFree( interpreter );
    }

    if( A == NULL )
    {
        return;
    }

    else
    {
        HYPRE_IJMatrixDestroy( A );
    }
}

HypreParMatrix* ParMult( HypreParMatrix* A, HypreParMatrix* B )
{
    hypre_ParCSRMatrix* ab;
    ab = hypre_ParMatmul( A->A_parcsr, B->A_parcsr );
    hypre_MatvecCommPkgCreate( ab );
    HypreParMatrix* tmpMat = new HypreParMatrix( A->pcomm, A->M(), A->N(), A->RowPart(), A->ColPart(), 0, 0 );
    hypre_IJMatrixObject( tmpMat->A ) = ab;
    /* Get the parcsr matrix object to use */
    HYPRE_IJMatrixGetObject( tmpMat->A, (void**)tmpMat->A_parcsr );
    return tmpMat;
}

HypreParMatrix* RAP( HypreParMatrix* A, HypreParMatrix* P )
{
    HYPRE_Int P_owns_its_col_starts = hypre_ParCSRMatrixOwnsColStarts( (hypre_ParCSRMatrix*)( P->A_parcsr ) );
    hypre_ParCSRMatrix* rap;
    hypre_BoomerAMGBuildCoarseOperator( P->A_parcsr, A->A_parcsr, P->A_parcsr, &rap );
    hypre_ParCSRMatrixSetNumNonzeros( rap );
    // hypre_MatvecCommPkgCreate(rap);
    /* Warning: hypre_BoomerAMGBuildCoarseOperator steals the col_starts
       from P (even if it does not own them)! */
    hypre_ParCSRMatrixSetRowStartsOwner( rap, 0 );
    hypre_ParCSRMatrixSetColStartsOwner( rap, 0 );

    if( P_owns_its_col_starts )
    {
        hypre_ParCSRMatrixSetColStartsOwner( P->A_parcsr, 1 );
    }

    HypreParMatrix* tmpMat = new HypreParMatrix( A->pcomm, A->M(), A->N(), A->RowPart(), A->ColPart(), 0, 0 );
    hypre_IJMatrixObject( tmpMat->A ) = rap;
    /* Get the parcsr matrix object to use */
    HYPRE_IJMatrixGetObject( tmpMat->A, (void**)tmpMat->A_parcsr );
    return tmpMat;
}

HypreParMatrix* RAP( HypreParMatrix* Rt, HypreParMatrix* A, HypreParMatrix* P )
{
    HYPRE_Int P_owns_its_col_starts  = hypre_ParCSRMatrixOwnsColStarts( (hypre_ParCSRMatrix*)( P->A_parcsr ) );
    HYPRE_Int Rt_owns_its_col_starts = hypre_ParCSRMatrixOwnsColStarts( (hypre_ParCSRMatrix*)( Rt->A_parcsr ) );
    hypre_ParCSRMatrix* rap;
    hypre_BoomerAMGBuildCoarseOperator( Rt->A_parcsr, A->A_parcsr, P->A_parcsr, &rap );
    hypre_ParCSRMatrixSetNumNonzeros( rap );

    // hypre_MatvecCommPkgCreate(rap);
    if( !P_owns_its_col_starts )
    {
        /* Warning: hypre_BoomerAMGBuildCoarseOperator steals the col_starts
           from P (even if it does not own them)! */
        hypre_ParCSRMatrixSetColStartsOwner( rap, 0 );
    }

    if( !Rt_owns_its_col_starts )
    {
        /* Warning: hypre_BoomerAMGBuildCoarseOperator steals the col_starts
           from P (even if it does not own them)! */
        hypre_ParCSRMatrixSetRowStartsOwner( rap, 0 );
    }

    HypreParMatrix* tmpMat = new HypreParMatrix( A->pcomm, A->M(), A->N(), A->RowPart(), A->ColPart(), 0, 0 );
    hypre_IJMatrixObject( tmpMat->A ) = rap;
    /* Get the parcsr matrix object to use */
    HYPRE_IJMatrixGetObject( tmpMat->A, (void**)tmpMat->A_parcsr );
    return tmpMat;
}

void EliminateBC( HypreParMatrix& A,
                  HypreParMatrix& Ae,
                  const std::vector< int >& ess_dof_list,
                  const HypreParVector& X,
                  HypreParVector& B )
{
    // B -= Ae*X
    Ae.Mult( -1.0, X, 1.0, B );
    hypre_CSRMatrix* A_diag = hypre_ParCSRMatrixDiag( (hypre_ParCSRMatrix*)A.A_parcsr );
    double* data            = hypre_CSRMatrixData( A_diag );
    HYPRE_Int* I            = hypre_CSRMatrixI( A_diag );
#ifdef MOAB_DEBUG
    HYPRE_Int* J            = hypre_CSRMatrixJ( A_diag );
    hypre_CSRMatrix* A_offd = hypre_ParCSRMatrixOffd( (hypre_ParCSRMatrix*)A.A_parcsr );
    HYPRE_Int* I_offd       = hypre_CSRMatrixI( A_offd );
    double* data_offd       = hypre_CSRMatrixData( A_offd );
#endif
    std::vector< HYPRE_Complex > bdata( ess_dof_list.size() ), xdata( ess_dof_list.size() );
    B.GetValues( ess_dof_list.size(), ess_dof_list.data(), bdata.data() );
    X.GetValues( ess_dof_list.size(), ess_dof_list.data(), xdata.data() );

    for( size_t i = 0; i < ess_dof_list.size(); i++ )
    {
        int r    = ess_dof_list[i];
        bdata[r] = data[I[r]] * xdata[r];
#ifdef MOAB_DEBUG

        // Check that in the rows specified by the ess_dof_list, the matrix A has
        // only one entry -- the diagonal.
        // if (I[r+1] != I[r]+1 || J[I[r]] != r || I_offd[r] != I_offd[r+1])
        if( J[I[r]] != r )
        {
            MB_SET_ERR_RET( "the diagonal entry must be the first entry in the row!" );
        }

        for( int j = I[r] + 1; j < I[r + 1]; j++ )
        {
            if( data[j] != 0.0 )
            {
                MB_SET_ERR_RET( "all off-diagonal entries must be zero!" );
            }
        }

        for( int j = I_offd[r]; j < I_offd[r + 1]; j++ )
        {
            if( data_offd[j] != 0.0 )
            {
                MB_SET_ERR_RET( "all off-diagonal entries must be zero!" );
            }
        }

#endif
    }
}

// Taubin or "lambda-mu" scheme, which alternates between positive and
// negative step sizes to approximate low-pass filter effect.

int ParCSRRelax_Taubin( hypre_ParCSRMatrix* A,  // matrix to relax with
                        hypre_ParVector* f,     // right-hand side
                        double lambda,
                        double mu,
                        int N,
                        double max_eig,
                        hypre_ParVector* u,  // initial/updated approximation
                        hypre_ParVector* r   // another temp vector
)
{
    hypre_CSRMatrix* A_diag = hypre_ParCSRMatrixDiag( A );
    HYPRE_Int num_rows      = hypre_CSRMatrixNumRows( A_diag );
    double* u_data          = hypre_VectorData( hypre_ParVectorLocalVector( u ) );
    double* r_data          = hypre_VectorData( hypre_ParVectorLocalVector( r ) );

    for( int i = 0; i < N; i++ )
    {
        // get residual: r = f - A*u
        hypre_ParVectorCopy( f, r );
        hypre_ParCSRMatrixMatvec( -1.0, A, u, 1.0, r );
        double coef;
        ( 0 == ( i % 2 ) ) ? coef = lambda : coef = mu;

        for( HYPRE_Int j = 0; j < num_rows; j++ )
        {
            u_data[j] += coef * r_data[j] / max_eig;
        }
    }

    return 0;
}

// FIR scheme, which uses Chebyshev polynomials and a window function
// to approximate a low-pass step filter.

int ParCSRRelax_FIR( hypre_ParCSRMatrix* A,  // matrix to relax with
                     hypre_ParVector* f,     // right-hand side
                     double max_eig,
                     int poly_order,
                     double* fir_coeffs,
                     hypre_ParVector* u,   // initial/updated approximation
                     hypre_ParVector* x0,  // temporaries
                     hypre_ParVector* x1,
                     hypre_ParVector* x2,
                     hypre_ParVector* x3 )

{
    hypre_CSRMatrix* A_diag = hypre_ParCSRMatrixDiag( A );
    HYPRE_Int num_rows      = hypre_CSRMatrixNumRows( A_diag );
    double* u_data          = hypre_VectorData( hypre_ParVectorLocalVector( u ) );
    double* x0_data         = hypre_VectorData( hypre_ParVectorLocalVector( x0 ) );
    double* x1_data         = hypre_VectorData( hypre_ParVectorLocalVector( x1 ) );
    double* x2_data         = hypre_VectorData( hypre_ParVectorLocalVector( x2 ) );
    double* x3_data         = hypre_VectorData( hypre_ParVectorLocalVector( x3 ) );
    hypre_ParVectorCopy( u, x0 );
    // x1 = f -A*x0/max_eig
    hypre_ParVectorCopy( f, x1 );
    hypre_ParCSRMatrixMatvec( -1.0, A, x0, 1.0, x1 );

    for( HYPRE_Int i = 0; i < num_rows; i++ )
    {
        x1_data[i] /= -max_eig;
    }

    // x1 = x0 -x1
    for( HYPRE_Int i = 0; i < num_rows; i++ )
    {
        x1_data[i] = x0_data[i] - x1_data[i];
    }

    // x3 = f0*x0 +f1*x1
    for( HYPRE_Int i = 0; i < num_rows; i++ )
    {
        x3_data[i] = fir_coeffs[0] * x0_data[i] + fir_coeffs[1] * x1_data[i];
    }

    for( int n = 2; n <= poly_order; n++ )
    {
        // x2 = f - A*x1/max_eig
        hypre_ParVectorCopy( f, x2 );
        hypre_ParCSRMatrixMatvec( -1.0, A, x1, 1.0, x2 );

        for( HYPRE_Int i = 0; i < num_rows; i++ )
        {
            x2_data[i] /= -max_eig;
        }

        // x2 = (x1-x0) +(x1-2*x2)
        // x3 = x3 +f[n]*x2
        // x0 = x1
        // x1 = x2

        for( HYPRE_Int i = 0; i < num_rows; i++ )
        {
            x2_data[i] = ( x1_data[i] - x0_data[i] ) + ( x1_data[i] - 2 * x2_data[i] );
            x3_data[i] += fir_coeffs[n] * x2_data[i];
            x0_data[i] = x1_data[i];
            x1_data[i] = x2_data[i];
        }
    }

    for( HYPRE_Int i = 0; i < num_rows; i++ )
    {
        u_data[i] = x3_data[i];
    }

    return 0;
}

}  // namespace moab

#endif