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#ifndef TEUCHOS_SERIALSPDDENSESOLVER_H
#define TEUCHOS_SERIALSPDDENSESOLVER_H

/*! \file Teuchos_SerialSpdDenseSolver.hpp
  \brief Templated class for constructing and using Hermitian positive definite dense matrices.
*/

#include "Teuchos_CompObject.hpp"
#include "Teuchos_BLAS.hpp"
#include "Teuchos_LAPACK.hpp"
#include "Teuchos_RCP.hpp"
#include "Teuchos_ConfigDefs.hpp"
#include "Teuchos_SerialSymDenseMatrix.hpp"
#include "Teuchos_SerialDenseSolver.hpp"
#include "Teuchos_SerialDenseMatrix.hpp"

#ifdef HAVE_TEUCHOSNUMERICS_EIGEN
#include "Eigen/Dense"
#endif

/*! \class Teuchos::SerialSpdDenseSolver
    \brief A class for constructing and using Hermitian positive definite dense matrices.

    The Teuchos::SerialSpdDenseSolver class enables the construction and use of a templated,
    Hermitian positive definite, double-precision dense matrices.  It is built on the BLAS and
    LAPACK via the Teuchos::BLAS and Teuchos::LAPACK classes.

    The Teuchos::SerialSpdDenseSolver class is intended to provide full-featured support for
    solving linear system problems for Hermitian positive definite matrices.  It is written on
    top of BLAS and LAPACK and thus has excellent performance and numerical capabilities.
    Using this class, one can either perform simple factorizations and solves or apply all the
    tricks available in LAPACK to get the best possible solution for very ill-conditioned problems.

    <b>Teuchos::SerialSpdDenseSolver vs. Teuchos::LAPACK</b>

    The Teuchos::LAPACK class provides access to most of the same functionality as Teuchos::SerialSpdDenseSolver.
    The primary difference is that Teuchos::LAPACK is a "thin" layer on top of LAPACK and
    Teuchos::SerialSpdDenseSolver attempts to provide easy access to the more sophisticated
    aspects of solving dense linear and eigensystems.
    <ul>
    <li> When you should use Teuchos::LAPACK:  If you are simply looking for a convenient wrapper
    around the Fortran LAPACK routines and you have a well-conditioned problem, you should probably
    use Teuchos::LAPACK directly.
    <li> When you should use Teuchos::SerialSpdDenseSolver: If you want to (or potentially want to)
    solve ill-conditioned problems or want to work with a more object-oriented interface, you should
    probably use Teuchos::SerialSpdDenseSolver.
    </ul>

    <b>Extracting Data from Teuchos::SerialSpdDenseSolver Objects</b>

    Once a Teuchos::SerialSpdDenseSolver is constructed, it is possible to view the data via access functions.

    \warning Use of these access functions cam be \e extremely dangerous from a data hiding perspective.

    <b>Vector and Utility Functions</b>

    Once a Teuchos::SerialSpdDenseSolver is constructed, several mathematical functions can be applied to
    the object.  Specifically:
    <ul>
    <li> Factorizations.
    <li> Solves.
    <li> Condition estimates.
    <li> Equilibration.
    <li> Norms.
    </ul>

    <b>Strategies for Solving Linear Systems</b>
    In many cases, linear systems can be accurately solved by simply computing the Cholesky factorization
    of the matrix and then performing a forward back solve with a given set of right hand side vectors.  However,
    in some instances, the factorization may be very poorly conditioned and the simple approach may not work.  In
    these situations, equilibration and iterative refinement may improve the accuracy, or prevent a breakdown in
    the factorization.

    Teuchos::SerialSpdDenseSolver will use equilibration with the factorization if, once the object
    is constructed and \e before it is factored, you call the function FactorWithEquilibration(true) to force
    equilibration to be used.  If you are uncertain if equilibration should be used, you may call the function
    ShouldEquilibrate() which will return true if equilibration could possibly help.  ShouldEquilibrate() uses
    guidelines specified in the LAPACK User Guide, namely if SCOND < 0.1 and AMAX < Underflow or AMAX > Overflow, to
    determine if equilibration \e might be useful.

    Teuchos::SerialSpdDenseSolver will use iterative refinement after a forward/back solve if you call
    SolveToRefinedSolution(true).  It will also compute forward and backward error estimates if you call
    EstimateSolutionErrors(true).  Access to the forward (back) error estimates is available via FERR() (BERR()).

    Examples using Teuchos::SerialSpdDenseSolver can be found in the Teuchos test directories.
*/

namespace Teuchos {

  template<typename OrdinalType, typename ScalarType>
  class SerialSpdDenseSolver : public CompObject, public Object, public BLAS<OrdinalType, ScalarType>,
                            public LAPACK<OrdinalType, ScalarType>
  {
  public:

    typedef typename Teuchos::ScalarTraits<ScalarType>::magnitudeType MagnitudeType;
#ifdef HAVE_TEUCHOSNUMERICS_EIGEN
    typedef typename Eigen::Matrix<ScalarType,Eigen::Dynamic,Eigen::Dynamic,Eigen::ColMajor> EigenMatrix;
    typedef typename Eigen::Matrix<ScalarType,Eigen::Dynamic,1> EigenVector;
    typedef typename Eigen::InnerStride<Eigen::Dynamic> EigenInnerStride;
    typedef typename Eigen::OuterStride<Eigen::Dynamic> EigenOuterStride;
    typedef typename Eigen::Map<EigenVector,0,EigenInnerStride > EigenVectorMap;
    typedef typename Eigen::Map<const EigenVector,0,EigenInnerStride > EigenConstVectorMap;
    typedef typename Eigen::Map<EigenMatrix,0,EigenOuterStride > EigenMatrixMap;
    typedef typename Eigen::Map<const EigenMatrix,0,EigenOuterStride > EigenConstMatrixMap;
    typedef typename Eigen::PermutationMatrix<Eigen::Dynamic,Eigen::Dynamic,OrdinalType> EigenPermutationMatrix;
    typedef typename Eigen::Array<OrdinalType,Eigen::Dynamic,1> EigenOrdinalArray;
    typedef typename Eigen::Map<EigenOrdinalArray> EigenOrdinalArrayMap;
    typedef typename Eigen::Array<ScalarType,Eigen::Dynamic,1> EigenScalarArray;
    typedef typename Eigen::Map<EigenScalarArray> EigenScalarArrayMap;
#endif

    //! @name Constructor/Destructor Methods
    //@{
    //! Default constructor; matrix should be set using setMatrix(), LHS and RHS set with setVectors().
    SerialSpdDenseSolver();


    //! SerialSpdDenseSolver destructor.
    virtual ~SerialSpdDenseSolver();
    //@}

    //! @name Set Methods
    //@{

    //! Sets the pointers for coefficient matrix.
    int setMatrix(const RCP<SerialSymDenseMatrix<OrdinalType,ScalarType> >& A_in);

    //! Sets the pointers for left and right hand side vector(s).
    /*! Row dimension of X must match column dimension of matrix A, row dimension of B
      must match row dimension of A.  X and B must have the same dimensions.
    */
    int setVectors(const RCP<SerialDenseMatrix<OrdinalType, ScalarType> >& X,
                   const RCP<SerialDenseMatrix<OrdinalType, ScalarType> >& B);
    //@}

    //! @name Strategy Modifying Methods
    //@{

    //! Causes equilibration to be called just before the matrix factorization as part of the call to \c factor.
    /*! This function must be called before the factorization is performed.
     */
    void factorWithEquilibration(bool flag) {equilibrate_ = flag; return;}

    //! Causes all solves to compute solution to best ability using iterative refinement.
    void solveToRefinedSolution(bool flag) {refineSolution_ = flag; return;}

    //! Causes all solves to estimate the forward and backward solution error.
    /*! Error estimates will be in the arrays FERR and BERR, resp, after the solve step is complete.
      These arrays are accessible via the FERR() and BERR() access functions.
    */
    void estimateSolutionErrors(bool flag);
    //@}

    //! @name Factor/Solve/Invert Methods
    //@{

    //! Computes the in-place Cholesky factorization of the matrix using the LAPACK routine \e DPOTRF.
    /*!
      \return Integer error code, set to 0 if successful.
    */
    int factor();

    //! Computes the solution X to AX = B for the \e this matrix and the B provided to SetVectors()..
    /*!
      \return Integer error code, set to 0 if successful.
    */
    int solve();

    //! Inverts the \e this matrix.
    /*! Note: This function works a little differently that DPOTRI in that it fills the entire
      matrix with the inverse, independent of the UPLO specification.

      \return Integer error code, set to 0 if successful. Otherwise returns the LAPACK error code INFO.
    */
    int invert();

    //! Computes the scaling vector S(i) = 1/sqrt(A(i,i) of the \e this matrix.
    /*!
      \return Integer error code, set to 0 if successful. Otherwise returns the LAPACK error code INFO.
    */
    int computeEquilibrateScaling();

    //! Equilibrates the \e this matrix.
    /*!
      \return Integer error code, set to 0 if successful. Otherwise returns the LAPACK error code INFO.
    */
    int equilibrateMatrix();

    //! Equilibrates the current RHS.
    /*!
      \return Integer error code, set to 0 if successful. Otherwise returns the LAPACK error code INFO.
    */
    int equilibrateRHS();

    //! Apply Iterative Refinement.
    /*!
      \return Integer error code, set to 0 if successful. Otherwise returns the LAPACK error code INFO.
    */
    int applyRefinement();

    //! Unscales the solution vectors if equilibration was used to solve the system.
    /*!
      \return Integer error code, set to 0 if successful. Otherwise returns the LAPACK error code INFO.
    */
    int unequilibrateLHS();

    //! Returns the reciprocal of the 1-norm condition number of the \e this matrix.
    /*!
      \param Value Out
      On return contains the reciprocal of the 1-norm condition number of the \e this matrix.

      \return Integer error code, set to 0 if successful. Otherwise returns the LAPACK error code INFO.
    */
    int reciprocalConditionEstimate(MagnitudeType & Value);
    //@}

    //! @name Query methods
    //@{

    //! Returns true if transpose of \e this matrix has and will be used.
    bool transpose() {return(transpose_);}

    //! Returns true if matrix is factored (factor available via AF() and LDAF()).
    bool factored() {return(factored_);}

    //! Returns true if factor is equilibrated (factor available via AF() and LDAF()).
    bool equilibratedA() {return(equilibratedA_);}

    //! Returns true if RHS is equilibrated (RHS available via B() and LDB()).
    bool equilibratedB() {return(equilibratedB_);}

    //! Returns true if the LAPACK general rules for equilibration suggest you should equilibrate the system.
    bool shouldEquilibrate() {computeEquilibrateScaling(); return(shouldEquilibrate_);}

    //! Returns true if forward and backward error estimated have been computed (available via FERR() and BERR()).
    bool solutionErrorsEstimated() {return(solutionErrorsEstimated_);}

    //! Returns true if matrix inverse has been computed (inverse available via AF() and LDAF()).
    bool inverted() {return(inverted_);}

    //! Returns true if the condition number of the \e this matrix has been computed (value available via ReciprocalConditionEstimate()).
    bool reciprocalConditionEstimated() {return(reciprocalConditionEstimated_);}

    //! Returns true if the current set of vectors has been solved.
    bool solved() {return(solved_);}

    //! Returns true if the current set of vectors has been refined.
    bool solutionRefined() {return(solutionRefined_);}
    //@}

    //! @name Data Accessor methods
    //@{

    //! Returns pointer to current matrix.
    RCP<SerialSymDenseMatrix<OrdinalType, ScalarType> > getMatrix()  const {return(Matrix_);}

    //! Returns pointer to factored matrix (assuming factorization has been performed).
    RCP<SerialSymDenseMatrix<OrdinalType, ScalarType> > getFactoredMatrix()  const {return(Factor_);}

    //! Returns pointer to current LHS.
    RCP<SerialDenseMatrix<OrdinalType, ScalarType> > getLHS() const {return(LHS_);}

    //! Returns pointer to current RHS.
    RCP<SerialDenseMatrix<OrdinalType, ScalarType> > getRHS() const {return(RHS_);}

    //! Returns row dimension of system.
    OrdinalType numRows()  const {return(numRowCols_);}

    //! Returns column dimension of system.
    OrdinalType numCols()  const {return(numRowCols_);}

    //! Returns the 1-Norm of the \e this matrix (returns -1 if not yet computed).
    MagnitudeType ANORM()  const {return(ANORM_);}

    //! Returns the reciprocal of the condition number of the \e this matrix (returns -1 if not yet computed).
    MagnitudeType RCOND()  const {return(RCOND_);}

    //! Ratio of smallest to largest equilibration scale factors for the \e this matrix (returns -1 if not yet computed).
    /*! If SCOND() is >= 0.1 and AMAX() is not close to overflow or underflow, then equilibration is not needed.
     */
    MagnitudeType SCOND() {return(SCOND_);};

    //! Returns the absolute value of the largest entry of the \e this matrix (returns -1 if not yet computed).
    MagnitudeType AMAX()  const {return(AMAX_);}

    //! Returns a pointer to the forward error estimates computed by LAPACK.
    std::vector<MagnitudeType> FERR()  const {return(FERR_);}

    //! Returns a pointer to the backward error estimates computed by LAPACK.
    std::vector<MagnitudeType> BERR()  const {return(BERR_);}

    //! Returns a pointer to the row scaling vector used for equilibration.
    std::vector<MagnitudeType> R()  const {return(R_);}

    //@}

    //! @name I/O methods
    //@{
    //! Print service methods; defines behavior of ostream << operator.
    void Print(std::ostream& os) const;
    //@}

  protected:

    void allocateWORK() { LWORK_ = 4*numRowCols_; WORK_.resize( LWORK_ ); return;}
    void allocateIWORK() { IWORK_.resize( numRowCols_ ); return;}
    void resetMatrix();
    void resetVectors();

    bool equilibrate_;
    bool shouldEquilibrate_;
    bool equilibratedA_;
    bool equilibratedB_;
    bool transpose_;
    bool factored_;
    bool estimateSolutionErrors_;
    bool solutionErrorsEstimated_;
    bool solved_;
    bool inverted_;
    bool reciprocalConditionEstimated_;
    bool refineSolution_;
    bool solutionRefined_;

    OrdinalType numRowCols_;
    OrdinalType LDA_;
    OrdinalType LDAF_;
    OrdinalType INFO_;
    OrdinalType LWORK_;

    std::vector<int> IWORK_;

    MagnitudeType ANORM_;
    MagnitudeType RCOND_;
    MagnitudeType SCOND_;
    MagnitudeType AMAX_;

    RCP<SerialSymDenseMatrix<OrdinalType, ScalarType> > Matrix_;
    RCP<SerialDenseMatrix<OrdinalType, ScalarType> > LHS_;
    RCP<SerialDenseMatrix<OrdinalType, ScalarType> > RHS_;
    RCP<SerialSymDenseMatrix<OrdinalType, ScalarType> > Factor_;

    ScalarType * A_;
    ScalarType * AF_;
    std::vector<MagnitudeType> FERR_;
    std::vector<MagnitudeType> BERR_;
    std::vector<ScalarType> WORK_;
    std::vector<MagnitudeType> R_;
#ifdef HAVE_TEUCHOSNUMERICS_EIGEN
    Eigen::LLT<EigenMatrix,Eigen::Upper> lltu_;
    Eigen::LLT<EigenMatrix,Eigen::Lower> lltl_;
#endif

  private:
    // SerialSpdDenseSolver copy constructor (put here because we don't want user access)

    SerialSpdDenseSolver(const SerialSpdDenseSolver<OrdinalType, ScalarType>& Source);
    SerialSpdDenseSolver & operator=(const SerialSpdDenseSolver<OrdinalType, ScalarType>& Source);

  };

  // Helper traits to distinguish work arrays for real and complex-valued datatypes.
  using namespace details;

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

template<typename OrdinalType, typename ScalarType>
SerialSpdDenseSolver<OrdinalType,ScalarType>::SerialSpdDenseSolver()
  : CompObject(),
    equilibrate_(false),
    shouldEquilibrate_(false),
    equilibratedA_(false),
    equilibratedB_(false),
    transpose_(false),
    factored_(false),
    estimateSolutionErrors_(false),
    solutionErrorsEstimated_(false),
    solved_(false),
    inverted_(false),
    reciprocalConditionEstimated_(false),
    refineSolution_(false),
    solutionRefined_(false),
    numRowCols_(0),
    LDA_(0),
    LDAF_(0),
    INFO_(0),
    LWORK_(0),
    ANORM_(ScalarTraits<MagnitudeType>::zero()),
    RCOND_(ScalarTraits<MagnitudeType>::zero()),
    SCOND_(ScalarTraits<MagnitudeType>::zero()),
    AMAX_(ScalarTraits<MagnitudeType>::zero()),
    A_(0),
    AF_(0)
{
  resetMatrix();
}
//=============================================================================

template<typename OrdinalType, typename ScalarType>
SerialSpdDenseSolver<OrdinalType,ScalarType>::~SerialSpdDenseSolver()
{}

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

template<typename OrdinalType, typename ScalarType>
void SerialSpdDenseSolver<OrdinalType,ScalarType>::resetVectors()
{
  LHS_ = Teuchos::null;
  RHS_ = Teuchos::null;
  reciprocalConditionEstimated_ = false;
  solutionRefined_ = false;
  solved_ = false;
  solutionErrorsEstimated_ = false;
  equilibratedB_ = false;
}
//=============================================================================

template<typename OrdinalType, typename ScalarType>
void SerialSpdDenseSolver<OrdinalType,ScalarType>::resetMatrix()
{
  resetVectors();
  equilibratedA_ = false;
  factored_ = false;
  inverted_ = false;
  numRowCols_ = 0;
  LDA_ = 0;
  LDAF_ = 0;
  ANORM_ = -ScalarTraits<MagnitudeType>::one();
  RCOND_ = -ScalarTraits<MagnitudeType>::one();
  SCOND_ = -ScalarTraits<MagnitudeType>::one();
  AMAX_ = -ScalarTraits<MagnitudeType>::one();
  A_ = 0;
  AF_ = 0;
  INFO_ = 0;
  LWORK_ = 0;
  R_.resize(0);
}
//=============================================================================

template<typename OrdinalType, typename ScalarType>
int SerialSpdDenseSolver<OrdinalType,ScalarType>::setMatrix(const RCP<SerialSymDenseMatrix<OrdinalType,ScalarType> >& A)
{
  resetMatrix();
  Matrix_ = A;
  Factor_ = A;
  numRowCols_ = A->numRows();
  LDA_ = A->stride();
  LDAF_ = LDA_;
  A_ = A->values();
  AF_ = A->values();
  return(0);
}
//=============================================================================

template<typename OrdinalType, typename ScalarType>
int SerialSpdDenseSolver<OrdinalType,ScalarType>::setVectors(const RCP<SerialDenseMatrix<OrdinalType,ScalarType> >& X,
                                                             const RCP<SerialDenseMatrix<OrdinalType,ScalarType> >& B)
{
  // Check that these new vectors are consistent.
  TEUCHOS_TEST_FOR_EXCEPTION(B->numRows()!=X->numRows() || B->numCols() != X->numCols(), std::invalid_argument,
                     "SerialSpdDenseSolver<T>::setVectors: X and B are not the same size!");
  TEUCHOS_TEST_FOR_EXCEPTION(B->values()==0, std::invalid_argument,
                     "SerialSpdDenseSolver<T>::setVectors: B is an empty SerialDenseMatrix<T>!");
  TEUCHOS_TEST_FOR_EXCEPTION(X->values()==0, std::invalid_argument,
                     "SerialSpdDenseSolver<T>::setVectors: X is an empty SerialDenseMatrix<T>!");
  TEUCHOS_TEST_FOR_EXCEPTION(B->stride()<1, std::invalid_argument,
                     "SerialSpdDenseSolver<T>::setVectors: B has an invalid stride!");
  TEUCHOS_TEST_FOR_EXCEPTION(X->stride()<1, std::invalid_argument,
                     "SerialSpdDenseSolver<T>::setVectors: X has an invalid stride!");

  resetVectors();
  LHS_ = X;
  RHS_ = B;
  return(0);
}
//=============================================================================

template<typename OrdinalType, typename ScalarType>
void SerialSpdDenseSolver<OrdinalType,ScalarType>::estimateSolutionErrors(bool flag)
{
  estimateSolutionErrors_ = flag;

  // If the errors are estimated, this implies that the solution must be refined
  refineSolution_ = refineSolution_ || flag;
}
//=============================================================================

template<typename OrdinalType, typename ScalarType>
int SerialSpdDenseSolver<OrdinalType,ScalarType>::factor() {

  if (factored()) return(0); // Already factored

  TEUCHOS_TEST_FOR_EXCEPTION(inverted(), std::logic_error,
                     "SerialSpdDenseSolver<T>::factor: Cannot factor an inverted matrix!");

  ANORM_ = Matrix_->normOne(); // Compute 1-Norm of A


  // If we want to refine the solution, then the factor must
  // be stored separatedly from the original matrix

  if (A_ == AF_)
    if (refineSolution_ ) {
      Factor_ = rcp( new SerialSymDenseMatrix<OrdinalType,ScalarType>(*Matrix_) );
      AF_ = Factor_->values();
      LDAF_ = Factor_->stride();
    }

  int ierr = 0;
  if (equilibrate_) ierr = equilibrateMatrix();

  if (ierr!=0) return(ierr);

  INFO_ = 0;

#ifdef HAVE_TEUCHOSNUMERICS_EIGEN
  EigenMatrixMap aMap( AF_, numRowCols_, numRowCols_, EigenOuterStride(LDAF_) );

  if (Matrix_->upper())
    lltu_.compute(aMap);
  else
    lltl_.compute(aMap);

#else
  this->POTRF(Matrix_->UPLO(), numRowCols_, AF_, LDAF_, &INFO_);
#endif

  factored_ = true;

  return(INFO_);
}

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

template<typename OrdinalType, typename ScalarType>
int SerialSpdDenseSolver<OrdinalType,ScalarType>::solve() {

  // We will call one of four routines depending on what services the user wants and
  // whether or not the matrix has been inverted or factored already.
  //
  // If the matrix has been inverted, use DGEMM to compute solution.
  // Otherwise, if the user want the matrix to be equilibrated or wants a refined solution, we will
  // call the X interface.
  // Otherwise, if the matrix is already factored we will call the TRS interface.
  // Otherwise, if the matrix is unfactored we will call the SV interface.

  int ierr = 0;
  if (equilibrate_) {
    ierr = equilibrateRHS();
  }
  if (ierr != 0) return(ierr);  // Can't equilibrate B, so return.

  TEUCHOS_TEST_FOR_EXCEPTION( RHS_==Teuchos::null, std::invalid_argument,
                     "SerialSpdDenseSolver<T>::solve: No right-hand side vector (RHS) has been set for the linear system!");
  TEUCHOS_TEST_FOR_EXCEPTION( LHS_==Teuchos::null, std::invalid_argument,
                     "SerialSpdDenseSolver<T>::solve: No solution vector (LHS) has been set for the linear system!");

  if (inverted()) {

    TEUCHOS_TEST_FOR_EXCEPTION( RHS_->values() == LHS_->values(), std::invalid_argument,
                        "SerialSpdDenseSolver<T>::solve: X and B must be different vectors if matrix is inverted.");
    TEUCHOS_TEST_FOR_EXCEPTION( (equilibratedA_ && !equilibratedB_) || (!equilibratedA_ && equilibratedB_) ,
                        std::logic_error, "SerialSpdDenseSolver<T>::solve: Matrix and vectors must be similarly scaled!");

    INFO_ = 0;
    this->GEMM(Teuchos::NO_TRANS, Teuchos::NO_TRANS, numRowCols_, RHS_->numCols(),
               numRowCols_, 1.0, AF_, LDAF_, RHS_->values(), RHS_->stride(), 0.0,
               LHS_->values(), LHS_->stride());
    if (INFO_!=0) return(INFO_);
    solved_ = true;
  }
  else {

    if (!factored()) factor(); // Matrix must be factored

    TEUCHOS_TEST_FOR_EXCEPTION( (equilibratedA_ && !equilibratedB_) || (!equilibratedA_ && equilibratedB_) ,
                        std::logic_error, "SerialSpdDenseSolver<T>::solve: Matrix and vectors must be similarly scaled!");

    if (RHS_->values()!=LHS_->values()) {
       (*LHS_) = (*RHS_); // Copy B to X if needed
    }
    INFO_ = 0;

#ifdef HAVE_TEUCHOSNUMERICS_EIGEN
    EigenMatrixMap rhsMap( RHS_->values(), RHS_->numRows(), RHS_->numCols(), EigenOuterStride(RHS_->stride()) );
    EigenMatrixMap lhsMap( LHS_->values(), LHS_->numRows(), LHS_->numCols(), EigenOuterStride(LHS_->stride()) );

  if (Matrix_->upper())
    lhsMap = lltu_.solve(rhsMap);
  else
    lhsMap = lltl_.solve(rhsMap);

#else
    this->POTRS(Matrix_->UPLO(), numRowCols_, RHS_->numCols(), AF_, LDAF_, LHS_->values(), LHS_->stride(), &INFO_);
#endif

    if (INFO_!=0) return(INFO_);
    solved_ = true;

  }

  // Warn users that the system should be equilibrated, but it wasn't.
  if (shouldEquilibrate() && !equilibratedA_)
    std::cout << "WARNING!  SerialSpdDenseSolver<T>::solve: System should be equilibrated!" << std::endl;

  int ierr1=0;
  if (refineSolution_ && !inverted()) ierr1 = applyRefinement();
  if (ierr1!=0)
    return(ierr1);

  if (equilibrate_) ierr1 = unequilibrateLHS();
  return(ierr1);
}
//=============================================================================

template<typename OrdinalType, typename ScalarType>
int SerialSpdDenseSolver<OrdinalType,ScalarType>::applyRefinement()
{
  TEUCHOS_TEST_FOR_EXCEPTION(!solved(), std::logic_error,
                     "SerialSpdDenseSolver<T>::applyRefinement: Must have an existing solution!");
  TEUCHOS_TEST_FOR_EXCEPTION(A_==AF_, std::logic_error,
                     "SerialSpdDenseSolver<T>::applyRefinement: Cannot apply refinement if no original copy of A!");


#ifdef HAVE_TEUCHOSNUMERICS_EIGEN
  // Implement templated PORFS or use Eigen.
  return (-1);
#else
  OrdinalType NRHS = RHS_->numCols();
  FERR_.resize( NRHS );
  BERR_.resize( NRHS );
  allocateWORK();
  allocateIWORK();

  INFO_ = 0;
  std::vector<typename details::lapack_traits<ScalarType>::iwork_type> PORFS_WORK( numRowCols_ );
  this->PORFS(Matrix_->UPLO(), numRowCols_, NRHS, A_, LDA_, AF_, LDAF_,
              RHS_->values(), RHS_->stride(), LHS_->values(), LHS_->stride(),
              &FERR_[0], &BERR_[0], &WORK_[0], &PORFS_WORK[0], &INFO_);

  solutionErrorsEstimated_ = true;
  reciprocalConditionEstimated_ = true;
  solutionRefined_ = true;

  return(INFO_);
#endif
}

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

template<typename OrdinalType, typename ScalarType>
int SerialSpdDenseSolver<OrdinalType,ScalarType>::computeEquilibrateScaling()
{
  if (R_.size()!=0) return(0); // Already computed

  R_.resize( numRowCols_ );

  INFO_ = 0;
  this->POEQU (numRowCols_, AF_, LDAF_, &R_[0], &SCOND_, &AMAX_, &INFO_);
  if (SCOND_<0.1*ScalarTraits<MagnitudeType>::one() ||
      AMAX_ < ScalarTraits<ScalarType>::rmin() ||
      AMAX_ > ScalarTraits<ScalarType>::rmax())
    shouldEquilibrate_ = true;

  return(INFO_);
}

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

template<typename OrdinalType, typename ScalarType>
int SerialSpdDenseSolver<OrdinalType,ScalarType>::equilibrateMatrix()
{
  OrdinalType i, j;
  int ierr = 0;

  if (equilibratedA_) return(0); // Already done.
  if (R_.size()==0) ierr = computeEquilibrateScaling(); // Compute R if needed.
  if (ierr!=0) return(ierr);     // If return value is not zero, then can't equilibrate.
  if (Matrix_->upper()) {
    if (A_==AF_) {
      ScalarType * ptr;
      for (j=0; j<numRowCols_; j++) {
        ptr = A_ + j*LDA_;
        ScalarType s1 = R_[j];
        for (i=0; i<=j; i++) {
          *ptr = *ptr*s1*R_[i];
          ptr++;
        }
      }
    }
    else {
      ScalarType * ptr;
      ScalarType * ptr1;
      for (j=0; j<numRowCols_; j++) {
        ptr = A_ + j*LDA_;
        ptr1 = AF_ + j*LDAF_;
        ScalarType s1 = R_[j];
        for (i=0; i<=j; i++) {
          *ptr = *ptr*s1*R_[i];
          ptr++;
          *ptr1 = *ptr1*s1*R_[i];
          ptr1++;
        }
      }
    }
  }
  else {
    if (A_==AF_) {
      ScalarType * ptr;
      for (j=0; j<numRowCols_; j++) {
        ptr = A_ + j + j*LDA_;
        ScalarType s1 = R_[j];
        for (i=j; i<numRowCols_; i++) {
          *ptr = *ptr*s1*R_[i];
          ptr++;
        }
      }
    }
    else {
      ScalarType * ptr;
      ScalarType * ptr1;
      for (j=0; j<numRowCols_; j++) {
        ptr = A_ + j + j*LDA_;
        ptr1 = AF_ + j + j*LDAF_;
        ScalarType s1 = R_[j];
        for (i=j; i<numRowCols_; i++) {
          *ptr = *ptr*s1*R_[i];
          ptr++;
          *ptr1 = *ptr1*s1*R_[i];
          ptr1++;
        }
      }
    }
  }

  equilibratedA_ = true;

  return(0);
}

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

template<typename OrdinalType, typename ScalarType>
int SerialSpdDenseSolver<OrdinalType,ScalarType>::equilibrateRHS()
{
  OrdinalType i, j;
  int ierr = 0;

  if (equilibratedB_) return(0); // Already done.
  if (R_.size()==0) ierr = computeEquilibrateScaling(); // Compute R if needed.
  if (ierr!=0) return(ierr);     // Can't count on R being computed.

  OrdinalType LDB = RHS_->stride(), NRHS = RHS_->numCols();
  ScalarType * B = RHS_->values();
  ScalarType * ptr;
  for (j=0; j<NRHS; j++) {
    ptr = B + j*LDB;
    for (i=0; i<numRowCols_; i++) {
      *ptr = *ptr*R_[i];
      ptr++;
    }
  }

  equilibratedB_ = true;

  return(0);
}

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

template<typename OrdinalType, typename ScalarType>
int SerialSpdDenseSolver<OrdinalType,ScalarType>::unequilibrateLHS()
{
  OrdinalType i, j;

  if (!equilibratedB_) return(0); // Nothing to do

  OrdinalType LDX = LHS_->stride(), NLHS = LHS_->numCols();
  ScalarType * X = LHS_->values();
  ScalarType * ptr;
  for (j=0; j<NLHS; j++) {
    ptr = X + j*LDX;
    for (i=0; i<numRowCols_; i++) {
      *ptr = *ptr*R_[i];
      ptr++;
    }
  }

  return(0);
}

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

template<typename OrdinalType, typename ScalarType>
int SerialSpdDenseSolver<OrdinalType,ScalarType>::invert()
{
#ifdef HAVE_TEUCHOSNUMERICS_EIGEN
  // Implement templated inverse or use Eigen.
  return (-1);
#else
  if (!factored()) factor(); // Need matrix factored.

  INFO_ = 0;
  this->POTRI( Matrix_->UPLO(), numRowCols_, AF_, LDAF_, &INFO_);

  // Copy lower/upper triangle to upper/lower triangle to make full inverse.
  if (Matrix_->upper())
    Matrix_->setLower();
  else
    Matrix_->setUpper();

  inverted_ = true;
  factored_ = false;

  return(INFO_);
#endif
}

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

template<typename OrdinalType, typename ScalarType>
int SerialSpdDenseSolver<OrdinalType,ScalarType>::reciprocalConditionEstimate(MagnitudeType & Value)
{
#ifdef HAVE_TEUCHOSNUMERICS_EIGEN
  // Implement templated GECON or use Eigen. Eigen currently doesn't have a condition estimation function.
  return (-1);
#else
  if (reciprocalConditionEstimated()) {
    Value = RCOND_;
    return(0); // Already computed, just return it.
  }

  if ( ANORM_<ScalarTraits<MagnitudeType>::zero() ) ANORM_ = Matrix_->normOne();

  int ierr = 0;
  if (!factored()) ierr = factor(); // Need matrix factored.
  if (ierr!=0) return(ierr);

  allocateWORK();
  allocateIWORK();

  // We will assume a one-norm condition number
  INFO_ = 0;
  std::vector<typename details::lapack_traits<ScalarType>::iwork_type> POCON_WORK( numRowCols_ );
  this->POCON( Matrix_->UPLO(), numRowCols_, AF_, LDAF_, ANORM_, &RCOND_, &WORK_[0], &POCON_WORK[0], &INFO_);
  reciprocalConditionEstimated_ = true;
  Value = RCOND_;

  return(INFO_);
#endif
}
//=============================================================================

template<typename OrdinalType, typename ScalarType>
void SerialSpdDenseSolver<OrdinalType,ScalarType>::Print(std::ostream& os) const {

  if (Matrix_!=Teuchos::null) os << "Solver Matrix"          << std::endl << *Matrix_ << std::endl;
  if (Factor_!=Teuchos::null) os << "Solver Factored Matrix" << std::endl << *Factor_ << std::endl;
  if (LHS_   !=Teuchos::null) os << "Solver LHS"             << std::endl << *LHS_    << std::endl;
  if (RHS_   !=Teuchos::null) os << "Solver RHS"             << std::endl << *RHS_    << std::endl;

}

} // namespace Teuchos

#endif /* TEUCHOS_SERIALSPDDENSESOLVER_H */
