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//        MueLu: A package for multigrid based preconditioning
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// @HEADER
#ifndef MUELU_AMESOSSMOOTHER_HPP
#define MUELU_AMESOSSMOOTHER_HPP

#include "MueLu_ConfigDefs.hpp"
#if defined(HAVE_MUELU_EPETRA) && defined(HAVE_MUELU_AMESOS)

#include <Teuchos_ParameterList.hpp>
#include <Xpetra_Matrix_fwd.hpp>

class Epetra_LinearProblem;
class Amesos_BaseSolver;

#include "MueLu_SmootherPrototype.hpp"
#include "MueLu_Exceptions.hpp"

#include "MueLu_Level_fwd.hpp"
#include "MueLu_FactoryBase_fwd.hpp"
#include "MueLu_Utilities_fwd.hpp"

namespace MueLu {

  /*!
    @class AmesosSmoother
    @ingroup MueLuSmootherClasses
    @brief Class that encapsulates Amesos direct solvers.

    This class creates an Amesos preconditioner factory.  The factory is capable of generating direct solvers
    based on the type and ParameterList passed into the constructor.  See the constructor for more information.
  */
  template <class Node = typename SmootherPrototype<double,int,int>::node_type>
  class AmesosSmoother : public SmootherPrototype<double, int, int, Node>
  {
    typedef double Scalar;
    typedef int    LocalOrdinal;
    typedef int    GlobalOrdinal;

#undef MUELU_AMESOSSMOOTHER_SHORT
#include "MueLu_UseShortNames.hpp"

  public:

    //! @name Constructors / destructors
    //@{

    /*! @brief Constructor

        Creates a MueLu interface to the direct solvers in the Amesos package.  The options are those specified in
        the Amesos user's manual.

        @param type solver type
        @param list options for the particular solver type

        Here is how to select the more commonly used direct solvers:

        - KLU (serial sparse direct solver)
            - <tt>type</tt> = <tt>Amesos-KLU</tt>
            - parameter list options
                - none required

        - SuperLU (serial sparse super-nodal direct solver)
            - <tt>type</tt> = <tt>Amesos-SuperLU</tt>
            - parameter list options
                - none required

        If you are using type=="", then either SuperLU or KLU are used by default.

        See also Amesos_Klu and Amesos_Superlu.

    */

    AmesosSmoother(const std::string& type = "", const Teuchos::ParameterList& paramList = Teuchos::ParameterList());

    //! Destructor
    virtual ~AmesosSmoother() { };

    //@}

    //! Input
    //@{

    void DeclareInput(Level& currentLevel) const;

    //@}

    //! @name Setup and Apply methods.
    //@{

    /*! @brief Set up the direct solver.
      This creates the underlying Amesos solver object according to the parameter list options passed into the
      AmesosSmoother constructor.  This includes doing a numeric factorization of the matrix.
    */
    void Setup(Level& currentLevel);

    /*! @brief Apply the direct solver.

        Solves the linear system <tt>AX=B</tt> using the constructed solver.

        @param X initial guess
        @param B right-hand side
        @param InitialGuessIsZero This option has no effect with this smoother
    */
    void Apply(MultiVector& X, const MultiVector& B, bool InitialGuessIsZero = false) const;

    //@}

    RCP<SmootherPrototype> Copy() const;

    //! @name Overridden from Teuchos::Describable
    //@{

    //! Return a simple one-line description of this object.
    std::string description() const;

    //! Print the object with some verbosity level to an FancyOStream object.
    //using MueLu::Describable::describe; // overloading, not hiding
    void print(Teuchos::FancyOStream& out, const VerbLevel verbLevel = Default) const;

    //@}

  private:

    // Important note:
    // linearProblem_ must be destroyed before A_, because destructor of linearProblem_ is using A_.
    // In C++, destructor of member objects are called in the reverse order they appear within the declaration for the class.
    // ==18029== Invalid read of size 8
    // ==18029==    at 0xC0780A: Epetra_LinearProblem::GetMatrix() const (Epetra_LinearProblem.h:173)
    // ==18029==    by 0xC5EC27: Amesos_Superlu::PrintTiming() const (Amesos_Superlu.cpp:664)
    // ==18029==    by 0xC628C6: Amesos_Superlu::~Amesos_Superlu() (Amesos_Superlu.cpp:108)

    //! amesos-specific key phrase that denote smoother type
    std::string type_;

    //! Matrix. Not used directly, but held inside of linearProblem_. So we have to keep an RCP pointer to it!
    RCP<Matrix> A_;

    //! Problem that Amesos uses internally.
    RCP<Epetra_LinearProblem> linearProblem_;

    //! pointer to Amesos solver object
    RCP<Amesos_BaseSolver> prec_;

  }; // class AmesosSmoother

  //! Non-member templated function GetAmesosSmoother() returns a new AmesosSmoother object
  // when <Scalar, LocalOrdinal, GlobalOrdinal> == <double, int, int>. Otherwise, an exception is thrown.
  //! This function simplifies the usage of AmesosSmoother objects inside of templates as templates do not have to be specialized for <double, int, int> (see DirectSolver for an example).
  template <class Scalar, class LocalOrdinal, class GlobalOrdinal, class Node>
  RCP<MueLu::SmootherPrototype<Scalar, LocalOrdinal, GlobalOrdinal, Node> >
  GetAmesosSmoother (const std::string& type = "", const Teuchos::ParameterList& paramList = Teuchos::ParameterList ()) {
    TEUCHOS_TEST_FOR_EXCEPTION(true, Exceptions::RuntimeError,
                               "AmesosSmoother cannot be used with Scalar != double, LocalOrdinal != int, GlobalOrdinal != int");
    return Teuchos::null;
  }

  // specialization for Epetra
#if defined(HAVE_MUELU_SERIAL)
  template <>
  inline RCP<MueLu::SmootherPrototype<double, int, int, Xpetra::EpetraNode> >
  GetAmesosSmoother<double, int, int, Xpetra::EpetraNode> (const std::string& type, const Teuchos::ParameterList& paramList) {
    return rcp (new MueLu::AmesosSmoother<Xpetra::EpetraNode>(type, paramList));
  }
#endif // HAVE_MUELU_SERIAL

} // namespace MueLu

#define MUELU_AMESOSSMOOTHER_SHORT

#endif // HAVE_MUELU_AMESOS
#endif // MUELU_AMESOSSMOOTHER_HPP
