Ifpack2_Experimental_RBILUK_def.hpp

// @HEADER
// *****************************************************************************
//       Ifpack2: Templated Object-Oriented Algebraic Preconditioner Package
//
// Copyright 2009 NTESS and the Ifpack2 contributors.
// SPDX-License-Identifier: BSD-3-Clause
// *****************************************************************************
// @HEADER
 
#ifndef IFPACK2_EXPERIMENTAL_CRSRBILUK_DEF_HPP
#define IFPACK2_EXPERIMENTAL_CRSRBILUK_DEF_HPP
 
#include "Tpetra_BlockMultiVector.hpp"
#include "Tpetra_BlockView.hpp"
#include "Tpetra_BlockCrsMatrix_Helpers_decl.hpp"
#include "Ifpack2_OverlappingRowMatrix.hpp"
#include "Ifpack2_Details_getCrsMatrix.hpp"
#include "Ifpack2_LocalFilter.hpp"
#include "Ifpack2_Utilities.hpp"
#include "Ifpack2_RILUK.hpp"
#include "KokkosSparse_sptrsv.hpp"
 
//#define IFPACK2_RBILUK_INITIAL
//#define IFPACK2_RBILUK_INITIAL_NOKK
 
#ifndef IFPACK2_RBILUK_INITIAL_NOKK
#include "KokkosBatched_Gemm_Decl.hpp"
#include "KokkosBatched_Gemm_Serial_Impl.hpp"
#include "KokkosBatched_Util.hpp"
#endif
 
namespace Ifpack2 {
 
namespace Experimental {
 
namespace
{
template<class MatrixType>
struct LocalRowHandler
{
  using LocalOrdinal = typename MatrixType::local_ordinal_type;
  using row_matrix_type = Tpetra::RowMatrix<
      typename MatrixType::scalar_type,
      LocalOrdinal,
      typename MatrixType::global_ordinal_type,
      typename MatrixType::node_type>;
  using inds_type = typename row_matrix_type::local_inds_host_view_type;
  using vals_type = typename row_matrix_type::values_host_view_type;
 
  LocalRowHandler(Teuchos::RCP<const row_matrix_type> A)
   : A_(std::move(A))
  {
    if (!A_->supportsRowViews())
    {
      const auto maxNumRowEntr = A_->getLocalMaxNumRowEntries();
      const auto blockSize = A_->getBlockSize();
      ind_nc_ = inds_type_nc("Ifpack2::RBILUK::LocalRowHandler::indices",maxNumRowEntr);
      val_nc_ = vals_type_nc("Ifpack2::RBILUK::LocalRowHandler::values",maxNumRowEntr*blockSize*blockSize);
    }
  }
 
  void getLocalRow(LocalOrdinal local_row, inds_type & InI, vals_type & InV, LocalOrdinal & NumIn)
  {
    if (A_->supportsRowViews())
    {
      A_->getLocalRowView(local_row,InI,InV);
      NumIn = (LocalOrdinal)InI.size();
    }
    else
    {
      size_t cnt;
      A_->getLocalRowCopy(local_row,ind_nc_,val_nc_,cnt);
      InI = ind_nc_;
      InV = val_nc_;
      NumIn = (LocalOrdinal)cnt;
    }
  }
 
private:
 
  using inds_type_nc = typename row_matrix_type::nonconst_local_inds_host_view_type;
  using vals_type_nc = typename row_matrix_type::nonconst_values_host_view_type;
 
  Teuchos::RCP<const row_matrix_type> A_;
  inds_type_nc ind_nc_;
  vals_type_nc val_nc_;
};
 
} // namespace
 
template<class MatrixType>
RBILUK<MatrixType>::RBILUK (const Teuchos::RCP<const row_matrix_type>& Matrix_in)
  : RILUK<row_matrix_type>(Teuchos::rcp_dynamic_cast<const row_matrix_type>(Matrix_in) )
{}
 
template<class MatrixType>
RBILUK<MatrixType>::RBILUK (const Teuchos::RCP<const block_crs_matrix_type>& Matrix_in)
  : RILUK<row_matrix_type>(Teuchos::rcp_dynamic_cast<const row_matrix_type>(Matrix_in) )
{}
 
 
template<class MatrixType>
RBILUK<MatrixType>::~RBILUK() {}
 
 
template<class MatrixType>
void
RBILUK<MatrixType>::setMatrix (const Teuchos::RCP<const block_crs_matrix_type>& A)
{
  // FIXME (mfh 04 Nov 2015) What about A_?  When does that get (re)set?
 
  // It's legal for A to be null; in that case, you may not call
  // initialize() until calling setMatrix() with a nonnull input.
  // Regardless, setting the matrix invalidates any previous
  // factorization.
  if (A.getRawPtr () != this->A_.getRawPtr ())
  {
    this->isAllocated_ = false;
    this->isInitialized_ = false;
    this->isComputed_ = false;
    this->Graph_ = Teuchos::null;
    L_block_ = Teuchos::null;
    U_block_ = Teuchos::null;
    D_block_ = Teuchos::null;
  }
}
 
 
 
template<class MatrixType>
const typename RBILUK<MatrixType>::block_crs_matrix_type&
RBILUK<MatrixType>::getLBlock () const
{
  TEUCHOS_TEST_FOR_EXCEPTION(
    L_block_.is_null (), std::runtime_error, "Ifpack2::RILUK::getL: The L factor "
    "is null.  Please call initialize() (and preferably also compute()) "
    "before calling this method.  If the input matrix has not yet been set, "
    "you must first call setMatrix() with a nonnull input matrix before you "
    "may call initialize() or compute().");
  return *L_block_;
}
 
 
template<class MatrixType>
const typename RBILUK<MatrixType>::block_crs_matrix_type&
RBILUK<MatrixType>::getDBlock () const
{
  TEUCHOS_TEST_FOR_EXCEPTION(
    D_block_.is_null (), std::runtime_error, "Ifpack2::RILUK::getD: The D factor "
    "(of diagonal entries) is null.  Please call initialize() (and "
    "preferably also compute()) before calling this method.  If the input "
    "matrix has not yet been set, you must first call setMatrix() with a "
    "nonnull input matrix before you may call initialize() or compute().");
  return *D_block_;
}
 
 
template<class MatrixType>
const typename RBILUK<MatrixType>::block_crs_matrix_type&
RBILUK<MatrixType>::getUBlock () const
{
  TEUCHOS_TEST_FOR_EXCEPTION(
    U_block_.is_null (), std::runtime_error, "Ifpack2::RILUK::getU: The U factor "
    "is null.  Please call initialize() (and preferably also compute()) "
    "before calling this method.  If the input matrix has not yet been set, "
    "you must first call setMatrix() with a nonnull input matrix before you "
    "may call initialize() or compute().");
  return *U_block_;
}
 
template<class MatrixType>
void RBILUK<MatrixType>::allocate_L_and_U_blocks ()
{
  using Teuchos::null;
  using Teuchos::rcp;
 
  if (! this->isAllocated_) {
    // Deallocate any existing storage.  This avoids storing 2x
    // memory, since RCP op= does not deallocate until after the
    // assignment.
    this->L_ = null;
    this->U_ = null;
    this->D_ = null;
    L_block_ = null;
    U_block_ = null;
    D_block_ = null;
 
    // Allocate Matrix using ILUK graphs
    L_block_ = rcp(new block_crs_matrix_type(*this->Graph_->getL_Graph (), blockSize_) );
    U_block_ = rcp(new block_crs_matrix_type(*this->Graph_->getU_Graph (), blockSize_) );
    D_block_ = rcp(new block_crs_matrix_type(*(Ifpack2::Details::computeDiagonalGraph(*(this->Graph_->getOverlapGraph()))),
                                             blockSize_) );
    L_block_->setAllToScalar (STM::zero ()); // Zero out L and U matrices
    U_block_->setAllToScalar (STM::zero ());
    D_block_->setAllToScalar (STM::zero ());
 
    // Allocate temp space for apply
    if (this->isKokkosKernelsSpiluk_) {
      const auto numRows = L_block_->getLocalNumRows();
      tmp_ = decltype(tmp_)("RBILUK::tmp_", numRows * blockSize_);
    }
  }
  this->isAllocated_ = true;
}
 
namespace
{
 
template<class MatrixType>
Teuchos::RCP<const typename RBILUK<MatrixType>::crs_graph_type>
getBlockCrsGraph(const Teuchos::RCP<const typename RBILUK<MatrixType>::row_matrix_type>& A)
{
  using local_ordinal_type = typename MatrixType::local_ordinal_type;
  using Teuchos::RCP;
  using Teuchos::rcp;
  using Teuchos::rcp_dynamic_cast;
  using Teuchos::rcp_const_cast;
  using Teuchos::rcpFromRef;
  using row_matrix_type = typename RBILUK<MatrixType>::row_matrix_type;
  using crs_graph_type = typename RBILUK<MatrixType>::crs_graph_type;
  using block_crs_matrix_type = typename RBILUK<MatrixType>::block_crs_matrix_type;
 
  auto A_local = RBILUK<MatrixType>::makeLocalFilter(A);
 
  {
    RCP<const LocalFilter<row_matrix_type> > filteredA =
      rcp_dynamic_cast<const LocalFilter<row_matrix_type> >(A_local);
    RCP<const OverlappingRowMatrix<row_matrix_type> > overlappedA = Teuchos::null;
    RCP<const block_crs_matrix_type > A_block = Teuchos::null;
    if (!filteredA.is_null ())
    {
      overlappedA = rcp_dynamic_cast<const OverlappingRowMatrix<row_matrix_type> > (filteredA->getUnderlyingMatrix ());
    }
 
    if (! overlappedA.is_null ()) {
      A_block = rcp_dynamic_cast<const block_crs_matrix_type>(overlappedA->getUnderlyingMatrix());
    }
    else if (!filteredA.is_null ()){
      //If there is no overlap, filteredA could be the block CRS matrix
      A_block = rcp_dynamic_cast<const block_crs_matrix_type>(filteredA->getUnderlyingMatrix());
    }
    else
    {
      A_block = rcp_dynamic_cast<const block_crs_matrix_type>(A_local);
    }
 
    if (!A_block.is_null()){
      return rcpFromRef(A_block->getCrsGraph());
    }
  }
 
  // Could not extract block crs, make graph manually
  {
    local_ordinal_type numRows = A_local->getLocalNumRows();
    Teuchos::Array<size_t> entriesPerRow(numRows);
    for(local_ordinal_type i = 0; i < numRows; i++) {
      entriesPerRow[i] = A_local->getNumEntriesInLocalRow(i);
    }
    RCP<crs_graph_type> A_local_crs_nc =
      rcp (new crs_graph_type (A_local->getRowMap (),
                                A_local->getColMap (),
                                entriesPerRow()));
 
    {
      using LocalRowHandler_t = LocalRowHandler<MatrixType>;
      LocalRowHandler_t localRowHandler(A_local);
      typename LocalRowHandler_t::inds_type indices;
      typename LocalRowHandler_t::vals_type values;
      for(local_ordinal_type i = 0; i < numRows; i++) {
        local_ordinal_type numEntries = 0;
        localRowHandler.getLocalRow(i, indices, values, numEntries);
        A_local_crs_nc->insertLocalIndices(i, numEntries,indices.data());
      }
    }
 
    A_local_crs_nc->fillComplete (A_local->getDomainMap (), A_local->getRangeMap ());
    return rcp_const_cast<const crs_graph_type> (A_local_crs_nc);
  }
 
}
 
 
} // namespace
 
template<class MatrixType>
void RBILUK<MatrixType>::initialize ()
{
  using Teuchos::RCP;
  using Teuchos::rcp;
  using Teuchos::rcp_dynamic_cast;
  const char prefix[] = "Ifpack2::Experimental::RBILUK::initialize: ";
 
  TEUCHOS_TEST_FOR_EXCEPTION
    (this->A_.is_null (), std::runtime_error, prefix << "The matrix (A_, the "
     "RowMatrix) is null.  Please call setMatrix() with a nonnull input "
     "before calling this method.");
  TEUCHOS_TEST_FOR_EXCEPTION
    (! this->A_->isFillComplete (), std::runtime_error, prefix << "The matrix "
     "(A_, the BlockCrsMatrix) is not fill complete.  You may not invoke "
     "initialize() or compute() with this matrix until the matrix is fill "
     "complete.  Note: BlockCrsMatrix is fill complete if and only if its "
     "underlying graph is fill complete.");
 
  blockSize_ = this->A_->getBlockSize();
  this->A_local_ = this->makeLocalFilter(this->A_);
 
  Teuchos::Time timer ("RBILUK::initialize");
  double startTime = timer.wallTime();
  { // Start timing
    Teuchos::TimeMonitor timeMon (timer);
 
    // Calling initialize() means that the user asserts that the graph
    // of the sparse matrix may have changed.  We must not just reuse
    // the previous graph in that case.
    //
    // Regarding setting isAllocated_ to false: Eventually, we may want
    // some kind of clever memory reuse strategy, but it's always
    // correct just to blow everything away and start over.
    this->isInitialized_ = false;
    this->isAllocated_ = false;
    this->isComputed_ = false;
    this->Graph_ = Teuchos::null;
 
    RCP<const crs_graph_type> matrixCrsGraph = getBlockCrsGraph<MatrixType>(this->A_);
    this->Graph_ = rcp (new Ifpack2::IlukGraph<crs_graph_type,kk_handle_type> (matrixCrsGraph,
        this->LevelOfFill_, 0));
 
    if (this->isKokkosKernelsSpiluk_) {
      this->KernelHandle_ = Teuchos::rcp (new kk_handle_type ());
      const auto numRows = this->A_local_->getLocalNumRows();
      KernelHandle_->create_spiluk_handle( KokkosSparse::Experimental::SPILUKAlgorithm::SEQLVLSCHD_TP1,
                                           numRows,
                                           2*this->A_local_->getLocalNumEntries()*(this->LevelOfFill_+1),
                                           2*this->A_local_->getLocalNumEntries()*(this->LevelOfFill_+1),
                                           blockSize_);
      this->Graph_->initialize(KernelHandle_); // this calls spiluk_symbolic
 
      this->L_Sptrsv_KernelHandle_ = Teuchos::rcp (new kk_handle_type ());
      this->U_Sptrsv_KernelHandle_ = Teuchos::rcp (new kk_handle_type ());
 
      KokkosSparse::Experimental::SPTRSVAlgorithm alg = KokkosSparse::Experimental::SPTRSVAlgorithm::SEQLVLSCHD_TP1;
 
      this->L_Sptrsv_KernelHandle_->create_sptrsv_handle(alg, numRows, true /*lower*/, blockSize_);
      this->U_Sptrsv_KernelHandle_->create_sptrsv_handle(alg, numRows, false /*upper*/, blockSize_);
    }
    else {
      this->Graph_->initialize ();
    }
 
    allocate_L_and_U_blocks ();
 
#ifdef IFPACK2_RBILUK_INITIAL
    initAllValues ();
#endif
  } // Stop timing
 
  this->isInitialized_ = true;
  this->numInitialize_ += 1;
  this->initializeTime_ += (timer.wallTime() - startTime);
}
 
 
template<class MatrixType>
void
RBILUK<MatrixType>::
initAllValues ()
{
  using Teuchos::RCP;
  typedef Tpetra::Map<LO,GO,node_type> map_type;
 
  LO NumIn = 0, NumL = 0, NumU = 0;
  bool DiagFound = false;
  size_t NumNonzeroDiags = 0;
  size_t MaxNumEntries = this->A_->getLocalMaxNumRowEntries();
  LO blockMatSize = blockSize_*blockSize_;
 
  // First check that the local row map ordering is the same as the local portion of the column map.
  // The extraction of the strictly lower/upper parts of A, as well as the factorization,
  // implicitly assume that this is the case.
  Teuchos::ArrayView<const GO> rowGIDs = this->A_->getRowMap()->getLocalElementList();
  Teuchos::ArrayView<const GO> colGIDs = this->A_->getColMap()->getLocalElementList();
  bool gidsAreConsistentlyOrdered=true;
  GO indexOfInconsistentGID=0;
  for (GO i=0; i<rowGIDs.size(); ++i) {
    if (rowGIDs[i] != colGIDs[i]) {
      gidsAreConsistentlyOrdered=false;
      indexOfInconsistentGID=i;
      break;
    }
  }
  TEUCHOS_TEST_FOR_EXCEPTION(gidsAreConsistentlyOrdered==false, std::runtime_error,
                             "The ordering of the local GIDs in the row and column maps is not the same"
                             << std::endl << "at index " << indexOfInconsistentGID
                             << ".  Consistency is required, as all calculations are done with"
                             << std::endl << "local indexing.");
 
  // Allocate temporary space for extracting the strictly
  // lower and upper parts of the matrix A.
  Teuchos::Array<LO> LI(MaxNumEntries);
  Teuchos::Array<LO> UI(MaxNumEntries);
  Teuchos::Array<scalar_type> LV(MaxNumEntries*blockMatSize);
  Teuchos::Array<scalar_type> UV(MaxNumEntries*blockMatSize);
 
  Teuchos::Array<scalar_type> diagValues(blockMatSize);
 
  L_block_->setAllToScalar (STM::zero ()); // Zero out L and U matrices
  U_block_->setAllToScalar (STM::zero ());
  D_block_->setAllToScalar (STM::zero ()); // Set diagonal values to zero
 
  // NOTE (mfh 27 May 2016) The factorization below occurs entirely on
  // host, so sync to host first.  The const_cast is unfortunate but
  // is our only option to make this correct.
 
  /*
  const_cast<block_crs_matrix_type&> (A).sync_host ();
  L_block_->sync_host ();
  U_block_->sync_host ();
  D_block_->sync_host ();
  // NOTE (mfh 27 May 2016) We're modifying L, U, and D on host.
  L_block_->modify_host ();
  U_block_->modify_host ();
  D_block_->modify_host ();
  */
 
  RCP<const map_type> rowMap = L_block_->getRowMap ();
 
  // First we copy the user's matrix into L and U, regardless of fill level.
  // It is important to note that L and U are populated using local indices.
  // This means that if the row map GIDs are not monotonically increasing
  // (i.e., permuted or gappy), then the strictly lower (upper) part of the
  // matrix is not the one that you would get if you based L (U) on GIDs.
  // This is ok, as the *order* of the GIDs in the rowmap is a better
  // expression of the user's intent than the GIDs themselves.
 
  //TODO BMK: Revisit this fence when BlockCrsMatrix is refactored.
  Kokkos::fence();
  using LocalRowHandler_t = LocalRowHandler<MatrixType>;
  LocalRowHandler_t localRowHandler(this->A_);
  typename LocalRowHandler_t::inds_type InI;
  typename LocalRowHandler_t::vals_type InV;
  for (size_t myRow=0; myRow<this->A_->getLocalNumRows(); ++myRow) {
    LO local_row = myRow;
 
    localRowHandler.getLocalRow(local_row, InI, InV, NumIn);
 
    // Split into L and U (we don't assume that indices are ordered).
    NumL = 0;
    NumU = 0;
    DiagFound = false;
 
    for (LO j = 0; j < NumIn; ++j) {
      const LO k = InI[j];
      const LO blockOffset = blockMatSize*j;
 
      if (k == local_row) {
        DiagFound = true;
        // Store perturbed diagonal in Tpetra::Vector D_
        for (LO jj = 0; jj < blockMatSize; ++jj)
          diagValues[jj] = this->Rthresh_ * InV[blockOffset+jj] + IFPACK2_SGN(InV[blockOffset+jj]) * this->Athresh_;
        D_block_->replaceLocalValues(local_row, &InI[j], diagValues.getRawPtr(), 1);
      }
      else if (k < 0) { // Out of range
        TEUCHOS_TEST_FOR_EXCEPTION(
          true, std::runtime_error, "Ifpack2::RILUK::initAllValues: current "
          "GID k = " << k << " < 0.  I'm not sure why this is an error; it is "
          "probably an artifact of the undocumented assumptions of the "
          "original implementation (likely copied and pasted from Ifpack).  "
          "Nevertheless, the code I found here insisted on this being an error "
          "state, so I will throw an exception here.");
      }
      else if (k < local_row) {
        LI[NumL] = k;
        const LO LBlockOffset = NumL*blockMatSize;
        for (LO jj = 0; jj < blockMatSize; ++jj)
          LV[LBlockOffset+jj] = InV[blockOffset+jj];
        NumL++;
      }
      else if (Teuchos::as<size_t>(k) <= rowMap->getLocalNumElements()) {
        UI[NumU] = k;
        const LO UBlockOffset = NumU*blockMatSize;
        for (LO jj = 0; jj < blockMatSize; ++jj)
          UV[UBlockOffset+jj] = InV[blockOffset+jj];
        NumU++;
      }
    }
 
    // Check in things for this row of L and U
 
    if (DiagFound) {
      ++NumNonzeroDiags;
    } else
    {
      for (LO jj = 0; jj < blockSize_; ++jj)
        diagValues[jj*(blockSize_+1)] = this->Athresh_;
      D_block_->replaceLocalValues(local_row, &local_row, diagValues.getRawPtr(), 1);
    }
 
    if (NumL) {
      L_block_->replaceLocalValues(local_row, &LI[0], &LV[0], NumL);
    }
 
    if (NumU) {
      U_block_->replaceLocalValues(local_row, &UI[0], &UV[0], NumU);
    }
  }
 
  // NOTE (mfh 27 May 2016) Sync back to device, in case compute()
  // ever gets a device implementation.
  /*
  {
    typedef typename block_crs_matrix_type::device_type device_type;
    const_cast<block_crs_matrix_type&> (A).template sync<device_type> ();
    L_block_->template sync<device_type> ();
    U_block_->template sync<device_type> ();
    D_block_->template sync<device_type> ();
  }
  */
  this->isInitialized_ = true;
}
 
namespace { // (anonymous)
 
// For a given Kokkos::View type, possibly unmanaged, get the
// corresponding managed Kokkos::View type.  This is handy for
// translating from little_block_type or little_host_vec_type (both
// possibly unmanaged) to their managed versions.
template<class LittleBlockType>
struct GetManagedView {
  static_assert (Kokkos::is_view<LittleBlockType>::value,
                 "LittleBlockType must be a Kokkos::View.");
  typedef Kokkos::View<typename LittleBlockType::non_const_data_type,
                       typename LittleBlockType::array_layout,
                       typename LittleBlockType::device_type> managed_non_const_type;
  static_assert (static_cast<int> (managed_non_const_type::rank) ==
                 static_cast<int> (LittleBlockType::rank),
                 "managed_non_const_type::rank != LittleBlock::rank.  "
                 "Please report this bug to the Ifpack2 developers.");
};
 
} // namespace (anonymous)
 
template<class MatrixType>
void RBILUK<MatrixType>::compute ()
{
  using Teuchos::RCP;
  using Teuchos::rcp;
  using Teuchos::Array;
 
  typedef impl_scalar_type IST;
  const char prefix[] = "Ifpack2::Experimental::RBILUK::compute: ";
 
  // initialize() checks this too, but it's easier for users if the
  // error shows them the name of the method that they actually
  // called, rather than the name of some internally called method.
  TEUCHOS_TEST_FOR_EXCEPTION
    (this->A_.is_null (), std::runtime_error, prefix << "The matrix (A_, "
     "the BlockCrsMatrix) is null.  Please call setMatrix() with a nonnull "
     "input before calling this method.");
  TEUCHOS_TEST_FOR_EXCEPTION
    (! this->A_->isFillComplete (), std::runtime_error, prefix << "The matrix "
     "(A_, the BlockCrsMatrix) is not fill complete.  You may not invoke "
     "initialize() or compute() with this matrix until the matrix is fill "
     "complete.  Note: BlockCrsMatrix is fill complete if and only if its "
     "underlying graph is fill complete.");
 
  if (! this->isInitialized ()) {
    initialize (); // Don't count this in the compute() time
  }
 
  // // NOTE (mfh 27 May 2016) The factorization below occurs entirely on
  // // host, so sync to host first.  The const_cast is unfortunate but
  // // is our only option to make this correct.
  // if (! A_block_.is_null ()) {
  //   Teuchos::RCP<block_crs_matrix_type> A_nc =
  //     Teuchos::rcp_const_cast<block_crs_matrix_type> (A_block_);
  //   //    A_nc->sync_host ();
  // }
  /*
  L_block_->sync_host ();
  U_block_->sync_host ();
  D_block_->sync_host ();
  // NOTE (mfh 27 May 2016) We're modifying L, U, and D on host.
  L_block_->modify_host ();
  U_block_->modify_host ();
  D_block_->modify_host ();
  */
 
  Teuchos::Time timer ("RBILUK::compute");
  double startTime = timer.wallTime();
  { // Start timing
    Teuchos::TimeMonitor timeMon (timer);
    this->isComputed_ = false;
 
    // MinMachNum should be officially defined, for now pick something a little
    // bigger than IEEE underflow value
 
//    const scalar_type MinDiagonalValue = STS::rmin ();
//    const scalar_type MaxDiagonalValue = STS::one () / MinDiagonalValue;
    if (!this->isKokkosKernelsSpiluk_) {
      initAllValues ();
      size_t NumIn;
      LO NumL, NumU, NumURead;
 
      // Get Maximum Row length
      const size_t MaxNumEntries =
        L_block_->getLocalMaxNumRowEntries () + U_block_->getLocalMaxNumRowEntries () + 1;
 
      const LO blockMatSize = blockSize_*blockSize_;
 
      // FIXME (mfh 08 Nov 2015, 24 May 2016) We need to move away from
      // expressing these strides explicitly, in order to finish #177
      // (complete Kokkos-ization of BlockCrsMatrix) thoroughly.
      const LO rowStride = blockSize_;
 
      Teuchos::Array<int> ipiv_teuchos(blockSize_);
      Kokkos::View<int*, Kokkos::HostSpace,
                   Kokkos::MemoryUnmanaged> ipiv (ipiv_teuchos.getRawPtr (), blockSize_);
      Teuchos::Array<IST> work_teuchos(blockSize_);
      Kokkos::View<IST*, Kokkos::HostSpace,
                   Kokkos::MemoryUnmanaged> work (work_teuchos.getRawPtr (), blockSize_);
 
      size_t num_cols = U_block_->getColMap()->getLocalNumElements();
      Teuchos::Array<int> colflag(num_cols);
 
      typename GetManagedView<little_block_host_type>::managed_non_const_type diagModBlock ("diagModBlock", blockSize_, blockSize_);
      typename GetManagedView<little_block_host_type>::managed_non_const_type matTmp ("matTmp", blockSize_, blockSize_);
      typename GetManagedView<little_block_host_type>::managed_non_const_type multiplier ("multiplier", blockSize_, blockSize_);
 
//    Teuchos::ArrayRCP<scalar_type> DV = D_->get1dViewNonConst(); // Get view of diagonal
 
      // Now start the factorization.
 
      // Need some integer workspace and pointers
      LO NumUU;
      for (size_t j = 0; j < num_cols; ++j) {
        colflag[j] = -1;
      }
      Teuchos::Array<LO> InI(MaxNumEntries, 0);
      Teuchos::Array<scalar_type> InV(MaxNumEntries*blockMatSize,STM::zero());
 
      const LO numLocalRows = L_block_->getLocalNumRows ();
      for (LO local_row = 0; local_row < numLocalRows; ++local_row) {
 
        // Fill InV, InI with current row of L, D and U combined
 
        NumIn = MaxNumEntries;
        local_inds_host_view_type colValsL;
        values_host_view_type valsL;
 
        L_block_->getLocalRowView(local_row, colValsL, valsL);
        NumL = (LO) colValsL.size();
        for (LO j = 0; j < NumL; ++j)
        {
          const LO matOffset = blockMatSize*j;
          little_block_host_type lmat((typename little_block_host_type::value_type*) &valsL[matOffset],blockSize_,rowStride);
          little_block_host_type lmatV((typename little_block_host_type::value_type*) &InV[matOffset],blockSize_,rowStride);
          //lmatV.assign(lmat);
          Tpetra::COPY (lmat, lmatV);
          InI[j] = colValsL[j];
        }
 
        little_block_host_type dmat = D_block_->getLocalBlockHostNonConst(local_row, local_row);
        little_block_host_type dmatV((typename little_block_host_type::value_type*) &InV[NumL*blockMatSize], blockSize_, rowStride);
        //dmatV.assign(dmat);
        Tpetra::COPY (dmat, dmatV);
        InI[NumL] = local_row;
 
        local_inds_host_view_type colValsU;
        values_host_view_type valsU;
        U_block_->getLocalRowView(local_row, colValsU, valsU);
        NumURead = (LO) colValsU.size();
        NumU = 0;
        for (LO j = 0; j < NumURead; ++j)
        {
          if (!(colValsU[j] < numLocalRows)) continue;
          InI[NumL+1+j] = colValsU[j];
          const LO matOffset = blockMatSize*(NumL+1+j);
          little_block_host_type umat((typename little_block_host_type::value_type*) &valsU[blockMatSize*j], blockSize_, rowStride);
          little_block_host_type umatV((typename little_block_host_type::value_type*) &InV[matOffset], blockSize_, rowStride);
          //umatV.assign(umat);
          Tpetra::COPY (umat, umatV);
          NumU += 1;
        }
        NumIn = NumL+NumU+1;
 
        // Set column flags
        for (size_t j = 0; j < NumIn; ++j) {
          colflag[InI[j]] = j;
        }
 
#ifndef IFPACK2_RBILUK_INITIAL
        for (LO i = 0; i < blockSize_; ++i)
          for (LO j = 0; j < blockSize_; ++j){
            {
              diagModBlock(i,j) = 0;
            }
          }
#else
        scalar_type diagmod = STM::zero (); // Off-diagonal accumulator
        Kokkos::deep_copy (diagModBlock, diagmod);
#endif
 
        for (LO jj = 0; jj < NumL; ++jj) {
          LO j = InI[jj];
          little_block_host_type currentVal((typename little_block_host_type::value_type*) &InV[jj*blockMatSize], blockSize_, rowStride); // current_mults++;
          //multiplier.assign(currentVal);
          Tpetra::COPY (currentVal, multiplier);
 
          const little_block_host_type dmatInverse = D_block_->getLocalBlockHostNonConst(j,j);
          // alpha = 1, beta = 0
#ifndef IFPACK2_RBILUK_INITIAL_NOKK
          KokkosBatched::SerialGemm
            <KokkosBatched::Trans::NoTranspose,
             KokkosBatched::Trans::NoTranspose,
             KokkosBatched::Algo::Gemm::Blocked>::invoke
            (STS::one (), currentVal, dmatInverse, STS::zero (), matTmp);
#else
          Tpetra::GEMM ("N", "N", STS::one (), currentVal, dmatInverse,
                        STS::zero (), matTmp);
#endif
          //blockMatOpts.square_matrix_matrix_multiply(reinterpret_cast<impl_scalar_type*> (currentVal.data ()), reinterpret_cast<impl_scalar_type*> (dmatInverse.data ()), reinterpret_cast<impl_scalar_type*> (matTmp.data ()), blockSize_);
          //currentVal.assign(matTmp);
          Tpetra::COPY (matTmp, currentVal);
          local_inds_host_view_type UUI;
          values_host_view_type UUV;
 
          U_block_->getLocalRowView(j, UUI, UUV);
          NumUU = (LO) UUI.size();
 
          if (this->RelaxValue_ == STM::zero ()) {
            for (LO k = 0; k < NumUU; ++k) {
              if (!(UUI[k] < numLocalRows)) continue;
              const int kk = colflag[UUI[k]];
              if (kk > -1) {
                little_block_host_type kkval((typename little_block_host_type::value_type*) &InV[kk*blockMatSize], blockSize_, rowStride);
                little_block_host_type uumat((typename little_block_host_type::value_type*) &UUV[k*blockMatSize], blockSize_, rowStride);
#ifndef IFPACK2_RBILUK_INITIAL_NOKK
                KokkosBatched::SerialGemm
                  <KokkosBatched::Trans::NoTranspose,
                   KokkosBatched::Trans::NoTranspose,
                   KokkosBatched::Algo::Gemm::Blocked>::invoke
                  ( magnitude_type(-STM::one ()), multiplier, uumat, STM::one (), kkval);
#else
                Tpetra::GEMM ("N", "N", magnitude_type(-STM::one ()), multiplier, uumat,
                              STM::one (), kkval);
#endif
                //blockMatOpts.square_matrix_matrix_multiply(reinterpret_cast<impl_scalar_type*> (multiplier.data ()), reinterpret_cast<impl_scalar_type*> (uumat.data ()), reinterpret_cast<impl_scalar_type*> (kkval.data ()), blockSize_, -STM::one(), STM::one());
              }
            }
          }
          else {
            for (LO k = 0; k < NumUU; ++k) {
              if (!(UUI[k] < numLocalRows)) continue;
              const int kk = colflag[UUI[k]];
              little_block_host_type uumat((typename little_block_host_type::value_type*) &UUV[k*blockMatSize], blockSize_, rowStride);
              if (kk > -1) {
                little_block_host_type kkval((typename little_block_host_type::value_type*) &InV[kk*blockMatSize], blockSize_, rowStride);
#ifndef IFPACK2_RBILUK_INITIAL_NOKK
                KokkosBatched::SerialGemm
                  <KokkosBatched::Trans::NoTranspose,
                   KokkosBatched::Trans::NoTranspose,
                   KokkosBatched::Algo::Gemm::Blocked>::invoke
                  (magnitude_type(-STM::one ()), multiplier, uumat, STM::one (), kkval);
#else
                Tpetra::GEMM ("N", "N", magnitude_type(-STM::one ()), multiplier, uumat,
                              STM::one (), kkval);
#endif
                //blockMatOpts.square_matrix_matrix_multiply(reinterpret_cast<impl_scalar_type*>(multiplier.data ()), reinterpret_cast<impl_scalar_type*>(uumat.data ()), reinterpret_cast<impl_scalar_type*>(kkval.data ()), blockSize_, -STM::one(), STM::one());
              }
              else {
#ifndef IFPACK2_RBILUK_INITIAL_NOKK
                KokkosBatched::SerialGemm
                  <KokkosBatched::Trans::NoTranspose,
                   KokkosBatched::Trans::NoTranspose,
                   KokkosBatched::Algo::Gemm::Blocked>::invoke
                  (magnitude_type(-STM::one ()), multiplier, uumat, STM::one (), diagModBlock);
#else
                Tpetra::GEMM ("N", "N", magnitude_type(-STM::one ()), multiplier, uumat,
                              STM::one (), diagModBlock);
#endif
                //blockMatOpts.square_matrix_matrix_multiply(reinterpret_cast<impl_scalar_type*>(multiplier.data ()), reinterpret_cast<impl_scalar_type*>(uumat.data ()), reinterpret_cast<impl_scalar_type*>(diagModBlock.data ()), blockSize_, -STM::one(), STM::one());
              }
            }
          }
        }
        if (NumL) {
          // Replace current row of L
          L_block_->replaceLocalValues (local_row, InI.getRawPtr (), InV.getRawPtr (), NumL);
        }
 
        // dmat.assign(dmatV);
        Tpetra::COPY (dmatV, dmat);
 
        if (this->RelaxValue_ != STM::zero ()) {
          //dmat.update(this->RelaxValue_, diagModBlock);
          Tpetra::AXPY (this->RelaxValue_, diagModBlock, dmat);
        }
 
//      if (STS::magnitude (DV[i]) > STS::magnitude (MaxDiagonalValue)) {
//        if (STS::real (DV[i]) < STM::zero ()) {
//          DV[i] = -MinDiagonalValue;
//        }
//        else {
//          DV[i] = MinDiagonalValue;
//        }
//      }
//      else
        {
          int lapackInfo = 0;
          for (int k = 0; k < blockSize_; ++k) {
            ipiv[k] = 0;
          }
 
          Tpetra::GETF2 (dmat, ipiv, lapackInfo);
          //lapack.GETRF(blockSize_, blockSize_, d_raw, blockSize_, ipiv.getRawPtr(), &lapackInfo);
          TEUCHOS_TEST_FOR_EXCEPTION(
            lapackInfo != 0, std::runtime_error, "Ifpack2::Experimental::RBILUK::compute: "
            "lapackInfo = " << lapackInfo << " which indicates an error in the factorization GETRF.");
 
          Tpetra::GETRI (dmat, ipiv, work, lapackInfo);
          //lapack.GETRI(blockSize_, d_raw, blockSize_, ipiv.getRawPtr(), work.getRawPtr(), lwork, &lapackInfo);
          TEUCHOS_TEST_FOR_EXCEPTION(
            lapackInfo != 0, std::runtime_error, "Ifpack2::Experimental::RBILUK::compute: "
            "lapackInfo = " << lapackInfo << " which indicates an error in the matrix inverse GETRI.");
        }
 
        for (LO j = 0; j < NumU; ++j) {
          little_block_host_type currentVal((typename little_block_host_type::value_type*) &InV[(NumL+1+j)*blockMatSize], blockSize_, rowStride); // current_mults++;
          // scale U by the diagonal inverse
#ifndef IFPACK2_RBILUK_INITIAL_NOKK
          KokkosBatched::SerialGemm
            <KokkosBatched::Trans::NoTranspose,
             KokkosBatched::Trans::NoTranspose,
             KokkosBatched::Algo::Gemm::Blocked>::invoke
            (STS::one (), dmat, currentVal, STS::zero (), matTmp);
#else
          Tpetra::GEMM ("N", "N", STS::one (), dmat, currentVal,
                        STS::zero (), matTmp);
#endif
          //blockMatOpts.square_matrix_matrix_multiply(reinterpret_cast<impl_scalar_type*>(dmat.data ()), reinterpret_cast<impl_scalar_type*>(currentVal.data ()), reinterpret_cast<impl_scalar_type*>(matTmp.data ()), blockSize_);
          //currentVal.assign(matTmp);
          Tpetra::COPY (matTmp, currentVal);
        }
 
        if (NumU) {
          // Replace current row of L and U
          U_block_->replaceLocalValues (local_row, &InI[NumL+1], &InV[blockMatSize*(NumL+1)], NumU);
        }
 
#ifndef IFPACK2_RBILUK_INITIAL
        // Reset column flags
        for (size_t j = 0; j < NumIn; ++j) {
          colflag[InI[j]] = -1;
        }
#else
        // Reset column flags
        for (size_t j = 0; j < num_cols; ++j) {
          colflag[j] = -1;
        }
#endif
      }
    } // !this->isKokkosKernelsSpiluk_
    else {
      RCP<const block_crs_matrix_type> A_local_bcrs = Details::getBcrsMatrix(this->A_local_);
      RCP<const crs_matrix_type> A_local_crs = Details::getCrsMatrix(this->A_local_);
      if (A_local_bcrs.is_null()) {
        if (A_local_crs.is_null()) {
          local_ordinal_type numRows = this->A_local_->getLocalNumRows();
          Array<size_t> entriesPerRow(numRows);
          for(local_ordinal_type i = 0; i < numRows; i++) {
            entriesPerRow[i] = this->A_local_->getNumEntriesInLocalRow(i);
          }
          RCP<crs_matrix_type> A_local_crs_nc =
            rcp (new crs_matrix_type (this->A_local_->getRowMap (),
                                      this->A_local_->getColMap (),
                                      entriesPerRow()));
          // copy entries into A_local_crs
          nonconst_local_inds_host_view_type indices("indices",this->A_local_->getLocalMaxNumRowEntries());
          nonconst_values_host_view_type values("values",this->A_local_->getLocalMaxNumRowEntries());
          for(local_ordinal_type i = 0; i < numRows; i++) {
            size_t numEntries = 0;
            this->A_local_->getLocalRowCopy(i, indices, values, numEntries);
            A_local_crs_nc->insertLocalValues(i, numEntries, reinterpret_cast<scalar_type*>(values.data()),indices.data());
          }
          A_local_crs_nc->fillComplete (this->A_local_->getDomainMap (), this->A_local_->getRangeMap ());
          A_local_crs = Teuchos::rcp_const_cast<const crs_matrix_type> (A_local_crs_nc);
        }
        // Create bcrs from crs
        // We can skip fillLogicalBlocks if we know the input is already filled
        if (blockSize_ > 1) {
          auto crs_matrix_block_filled = Tpetra::fillLogicalBlocks(*A_local_crs, blockSize_);
          A_local_bcrs = Tpetra::convertToBlockCrsMatrix(*crs_matrix_block_filled, blockSize_);
        }
        else {
          A_local_bcrs = Tpetra::convertToBlockCrsMatrix(*A_local_crs, blockSize_);
        }
      }
 
      TEUCHOS_TEST_FOR_EXCEPTION(
        this->isKokkosKernelsStream_, std::runtime_error, "Ifpack2::RBILUK::compute: "
        "streams are not yet supported.");
 
      auto lclMtx = A_local_bcrs->getLocalMatrixDevice();
      auto A_local_rowmap  = lclMtx.graph.row_map;
      auto A_local_entries = lclMtx.graph.entries;
      auto A_local_values  = lclMtx.values;
 
      // L_block_->resumeFill ();
      // U_block_->resumeFill ();
 
      if (L_block_->isLocallyIndexed ()) {
        L_block_->setAllToScalar (STS::zero ()); // Zero out L and U matrices
        U_block_->setAllToScalar (STS::zero ());
      }
 
      using row_map_type = typename local_matrix_device_type::row_map_type;
 
      auto lclL = L_block_->getLocalMatrixDevice();
      row_map_type L_rowmap  = lclL.graph.row_map;
      auto L_entries = lclL.graph.entries;
      auto L_values  = lclL.values;
 
      auto lclU = U_block_->getLocalMatrixDevice();
      row_map_type U_rowmap  = lclU.graph.row_map;
      auto U_entries = lclU.graph.entries;
      auto U_values  = lclU.values;
 
      KokkosSparse::Experimental::spiluk_numeric( KernelHandle_.getRawPtr(), this->LevelOfFill_,
                                                  A_local_rowmap, A_local_entries, A_local_values,
                                                  L_rowmap, L_entries, L_values, U_rowmap, U_entries, U_values );
 
      // Now call symbolic for sptrsvs
      KokkosSparse::Experimental::sptrsv_symbolic(L_Sptrsv_KernelHandle_.getRawPtr(), L_rowmap, L_entries, L_values);
      KokkosSparse::Experimental::sptrsv_symbolic(U_Sptrsv_KernelHandle_.getRawPtr(), U_rowmap, U_entries, U_values);
    }
  } // Stop timing
 
  // Sync everything back to device, for efficient solves.
  /*
  {
    typedef typename block_crs_matrix_type::device_type device_type;
    if (! A_block_.is_null ()) {
      Teuchos::RCP<block_crs_matrix_type> A_nc =
        Teuchos::rcp_const_cast<block_crs_matrix_type> (A_block_);
      A_nc->template sync<device_type> ();
    }
    L_block_->template sync<device_type> ();
    U_block_->template sync<device_type> ();
    D_block_->template sync<device_type> ();
  }
  */
 
  this->isComputed_ = true;
  this->numCompute_ += 1;
  this->computeTime_ += (timer.wallTime() - startTime);
}
 
 
template<class MatrixType>
void
RBILUK<MatrixType>::
apply (const Tpetra::MultiVector<scalar_type,local_ordinal_type,global_ordinal_type,node_type>& X,
       Tpetra::MultiVector<scalar_type,local_ordinal_type,global_ordinal_type,node_type>& Y,
       Teuchos::ETransp mode,
       scalar_type alpha,
       scalar_type beta) const
{
  using Teuchos::RCP;
  typedef Tpetra::BlockMultiVector<scalar_type,
    local_ordinal_type, global_ordinal_type, node_type> BMV;
 
  TEUCHOS_TEST_FOR_EXCEPTION(
    this->A_.is_null (), std::runtime_error, "Ifpack2::Experimental::RBILUK::apply: The matrix is "
    "null.  Please call setMatrix() with a nonnull input, then initialize() "
    "and compute(), before calling this method.");
  TEUCHOS_TEST_FOR_EXCEPTION(
    ! this->isComputed (), std::runtime_error,
    "Ifpack2::Experimental::RBILUK::apply: If you have not yet called compute(), "
    "you must call compute() before calling this method.");
  TEUCHOS_TEST_FOR_EXCEPTION(
    X.getNumVectors () != Y.getNumVectors (), std::invalid_argument,
    "Ifpack2::Experimental::RBILUK::apply: X and Y do not have the same number of columns.  "
    "X.getNumVectors() = " << X.getNumVectors ()
    << " != Y.getNumVectors() = " << Y.getNumVectors () << ".");
  TEUCHOS_TEST_FOR_EXCEPTION(
    STS::isComplex && mode == Teuchos::CONJ_TRANS, std::logic_error,
    "Ifpack2::Experimental::RBILUK::apply: mode = Teuchos::CONJ_TRANS is not implemented for "
    "complex Scalar type.  Please talk to the Ifpack2 developers to get this "
    "fixed.  There is a FIXME in this file about this very issue.");
 
  const LO blockMatSize = blockSize_*blockSize_;
 
  const LO rowStride = blockSize_;
 
  BMV yBlock (Y, * (this->Graph_->getA_Graph()->getDomainMap ()), blockSize_);
  const BMV xBlock (X, * (this->A_->getColMap ()), blockSize_);
 
  Teuchos::Array<scalar_type> lclarray(blockSize_);
  little_host_vec_type lclvec((typename little_host_vec_type::value_type*)&lclarray[0], blockSize_);
  const scalar_type one = STM::one ();
  const scalar_type zero = STM::zero ();
 
  Teuchos::Time timer ("RBILUK::apply");
  double startTime = timer.wallTime();
  { // Start timing
    Teuchos::TimeMonitor timeMon (timer);
    if (!this->isKokkosKernelsSpiluk_) {
      if (alpha == one && beta == zero) {
        if (mode == Teuchos::NO_TRANS) { // Solve L (D (U Y)) = X for Y.
          // Start by solving L C = X for C.  C must have the same Map
          // as D.  We have to use a temp multivector, since our
          // implementation of triangular solves does not allow its
          // input and output to alias one another.
          //
          // FIXME (mfh 24 Jan 2014) Cache this temp multivector.
          const LO numVectors = xBlock.getNumVectors();
          BMV cBlock (* (this->Graph_->getA_Graph()->getDomainMap ()), blockSize_, numVectors);
          BMV rBlock (* (this->Graph_->getA_Graph()->getDomainMap ()), blockSize_, numVectors);
          for (LO imv = 0; imv < numVectors; ++imv)
          {
            for (size_t i = 0; i < D_block_->getLocalNumRows(); ++i)
            {
              LO local_row = i;
              const_host_little_vec_type xval =
                xBlock.getLocalBlockHost(local_row, imv, Tpetra::Access::ReadOnly);
              little_host_vec_type cval =
                cBlock.getLocalBlockHost(local_row, imv, Tpetra::Access::OverwriteAll);
              //cval.assign(xval);
              Tpetra::COPY (xval, cval);
 
              local_inds_host_view_type colValsL;
              values_host_view_type valsL;
              L_block_->getLocalRowView(local_row, colValsL, valsL);
              LO NumL = (LO) colValsL.size();
 
              for (LO j = 0; j < NumL; ++j)
              {
                LO col = colValsL[j];
                const_host_little_vec_type prevVal =
                  cBlock.getLocalBlockHost(col, imv, Tpetra::Access::ReadOnly);
 
                const LO matOffset = blockMatSize*j;
                little_block_host_type lij((typename little_block_host_type::value_type*) &valsL[matOffset],blockSize_,rowStride);
 
                //cval.matvecUpdate(-one, lij, prevVal);
                Tpetra::GEMV (-one, lij, prevVal, cval);
              }
            }
          }
 
          // Solve D R = C. Note that D has been replaced by D^{-1} at this point.
          D_block_->applyBlock(cBlock, rBlock);
 
          // Solve U Y = R.
          for (LO imv = 0; imv < numVectors; ++imv)
          {
            const LO numRows = D_block_->getLocalNumRows();
            for (LO i = 0; i < numRows; ++i)
            {
              LO local_row = (numRows-1)-i;
              const_host_little_vec_type rval =
                rBlock.getLocalBlockHost(local_row, imv, Tpetra::Access::ReadOnly);
              little_host_vec_type yval =
                yBlock.getLocalBlockHost(local_row, imv, Tpetra::Access::OverwriteAll);
              //yval.assign(rval);
              Tpetra::COPY (rval, yval);
 
              local_inds_host_view_type colValsU;
              values_host_view_type valsU;
              U_block_->getLocalRowView(local_row, colValsU, valsU);
              LO NumU = (LO) colValsU.size();
 
              for (LO j = 0; j < NumU; ++j)
              {
                LO col = colValsU[NumU-1-j];
                const_host_little_vec_type prevVal =
                  yBlock.getLocalBlockHost(col, imv, Tpetra::Access::ReadOnly);
 
                const LO matOffset = blockMatSize*(NumU-1-j);
                little_block_host_type uij((typename little_block_host_type::value_type*) &valsU[matOffset], blockSize_, rowStride);
 
                //yval.matvecUpdate(-one, uij, prevVal);
                Tpetra::GEMV (-one, uij, prevVal, yval);
              }
            }
          }
        }
        else { // Solve U^P (D^P (L^P Y)) = X for Y (where P is * or T).
          TEUCHOS_TEST_FOR_EXCEPTION(
            true, std::runtime_error,
            "Ifpack2::Experimental::RBILUK::apply: transpose apply is not implemented for the block algorithm");
        }
      }
      else { // alpha != 1 or beta != 0
        if (alpha == zero) {
          if (beta == zero) {
            Y.putScalar (zero);
          } else {
            Y.scale (beta);
          }
        } else { // alpha != zero
          MV Y_tmp (Y.getMap (), Y.getNumVectors ());
          apply (X, Y_tmp, mode);
          Y.update (alpha, Y_tmp, beta);
        }
      }
    }
    else {
      // Kokkos kernels impl.
      auto X_views = X.getLocalViewDevice(Tpetra::Access::ReadOnly);
      auto Y_views = Y.getLocalViewDevice(Tpetra::Access::ReadWrite);
 
      auto lclL = L_block_->getLocalMatrixDevice();
      auto L_rowmap  = lclL.graph.row_map;
      auto L_entries = lclL.graph.entries;
      auto L_values  = lclL.values;
 
      auto lclU = U_block_->getLocalMatrixDevice();
      auto U_rowmap  = lclU.graph.row_map;
      auto U_entries = lclU.graph.entries;
      auto U_values  = lclU.values;
 
      if (mode == Teuchos::NO_TRANS) {
        {
          const LO numVecs = X.getNumVectors();
          for (LO vec = 0; vec < numVecs; ++vec) {
            auto X_view = Kokkos::subview(X_views, Kokkos::ALL(), vec);
            auto Y_view = Kokkos::subview(Y_views, Kokkos::ALL(), vec);
            KokkosSparse::Experimental::sptrsv_solve(L_Sptrsv_KernelHandle_.getRawPtr(), L_rowmap, L_entries, L_values, X_view, tmp_);
          }
        }
 
        {
          const LO numVecs = X.getNumVectors();
          for (LO vec = 0; vec < numVecs; ++vec) {
            auto Y_view = Kokkos::subview(Y_views, Kokkos::ALL(), vec);
            KokkosSparse::Experimental::sptrsv_solve(U_Sptrsv_KernelHandle_.getRawPtr(), U_rowmap, U_entries, U_values, tmp_, Y_view);
          }
        }
 
        KokkosBlas::axpby(alpha, Y_views, beta, Y_views);
      }
      else {
        TEUCHOS_TEST_FOR_EXCEPTION(
          true, std::runtime_error,
          "Ifpack2::Experimental::RBILUK::apply: transpose apply is not implemented for the block algorithm");
      }
 
      //Y.getWrappedDualView().sync();
    }
  } // Stop timing
 
  this->numApply_ += 1;
  this->applyTime_ += (timer.wallTime() - startTime);
}
 
 
template<class MatrixType>
std::string RBILUK<MatrixType>::description () const
{
  std::ostringstream os;
 
  // Output is a valid YAML dictionary in flow style.  If you don't
  // like everything on a single line, you should call describe()
  // instead.
  os << "\"Ifpack2::Experimental::RBILUK\": {";
  os << "Initialized: " << (this->isInitialized () ? "true" : "false") << ", "
     << "Computed: " << (this->isComputed () ? "true" : "false") << ", ";
 
  os << "Level-of-fill: " << this->getLevelOfFill() << ", ";
 
  if (this->A_.is_null ()) {
    os << "Matrix: null";
  }
  else {
    os << "Global matrix dimensions: ["
       << this->A_->getGlobalNumRows () << ", " << this->A_->getGlobalNumCols () << "]"
       << ", Global nnz: " << this->A_->getGlobalNumEntries();
  }
 
  os << "}";
  return os.str ();
}
 
} // namespace Experimental
 
} // namespace Ifpack2
 
// FIXME (mfh 26 Aug 2015) We only need to do instantiation for
// MatrixType = Tpetra::RowMatrix.  Conversions to BlockCrsMatrix are
// handled internally via dynamic cast.
 
#define IFPACK2_EXPERIMENTAL_RBILUK_INSTANT(S,LO,GO,N)                            \
  template class Ifpack2::Experimental::RBILUK< Tpetra::BlockCrsMatrix<S, LO, GO, N> >; \
  template class Ifpack2::Experimental::RBILUK< Tpetra::RowMatrix<S, LO, GO, N> >;
 
#endif