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//        MueLu: A package for multigrid based preconditioning
//                  Copyright 2012 Sandia Corporation
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// @HEADER
#ifndef MUELU_SMOOTHERBASE_HPP
#define MUELU_SMOOTHERBASE_HPP

#include <Xpetra_MultiVector.hpp>

#include "MueLu_ConfigDefs.hpp"
#include "MueLu_BaseClass.hpp"

namespace MueLu {
  /*!
    @class SmootherBase
    @ingroup MueLuSmootherClasses 
    @brief Base class for smoothers

    This has the signature for the required Apply function and contains data that is generic across all
    smoothers.
  */

  template <class Scalar = Xpetra::MultiVector<>::scalar_type,
            class LocalOrdinal = typename Xpetra::MultiVector<Scalar>::local_ordinal_type,
            class GlobalOrdinal = typename Xpetra::MultiVector<Scalar, LocalOrdinal>::global_ordinal_type,
            class Node = typename Xpetra::MultiVector<Scalar, LocalOrdinal, GlobalOrdinal>::node_type>
  class SmootherBase : public virtual BaseClass {
  public:
    typedef Scalar scalar_type;
    typedef LocalOrdinal local_ordinal_type;
    typedef GlobalOrdinal global_ordinal_type;
    typedef Node node_type;

  private:

#undef MUELU_SMOOTHERBASE_SHORT
#include "MueLu_UseShortNames.hpp"

  public:
    //@{ Constructors/Destructors.
    SmootherBase() {}

    virtual ~SmootherBase() {}
    //@}

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

    //! Apply smoother.
    virtual void Apply(MultiVector& x, const MultiVector& rhs, bool InitialGuessIsZero = false) const = 0;

    //@}

  }; //class SmootherBase
} //namespace MueLu

#define MUELU_SMOOTHERBASE_SHORT

#endif //ifndef MUELU_SMOOTHERBASE_HPP

// SmootherBase = Interface used by Hierarchy.Iterate(). Minimal condition to be used as smoother.
// SmootherPrototype = minimal interface used by the generic SmootherFactory.
// Note that one can implements and use his own SmootherFactory. In this case, SmootherBase is enough.
// AdvSmootherPrototype = for more complex case of reusing setup between presmoother and postsmoother
