Thyra_ScaledIdentityLinearOpWithSolve.hpp

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// @HEADER
// ****************************************************************************
//                Tempus: Copyright (2017) Sandia Corporation
//
// Distributed under BSD 3-clause license (See accompanying file Copyright.txt)
// ****************************************************************************
// @HEADER

#ifndef Thyra_ScaledIdentityLinearOpWithSolve_hpp
#define Thyra_ScaledIdentityLinearOpWithSolve_hpp

#include "Thyra_LinearOpWithSolveBase.hpp"
#include "Thyra_MultiVectorStdOps.hpp"

namespace Thyra {

/**
 * \brief Implicit concrete <tt>LinearOpBase</tt> subclass that
 * takes a flattended out multi-vector and performs a multi-RHS apply with it.
 */
template<class Scalar>
class ScaledIdentityLinearOpWithSolve :
    virtual public LinearOpWithSolveBase<Scalar>
{
public:

  /** @name Constructors/initializers/accessors */
  //@{

  /** \brief Construct to uninitialized. */
  ScaledIdentityLinearOpWithSolve() {}

  void initialize(const RCP<const VectorSpaceBase<Scalar> >& space,
                  const Scalar& s)
  {
    validateInitialize(space);
    space_ = space;
    s_ = s;
  }

  void uninitialize()
  {
    space_ = Teuchos::null;
  }

  RCP< const VectorSpaceBase<Scalar> > space() const { return space_; }
  Scalar scale() const { return s_; }
  void setScale(const Scalar& s) { s_ = s; }

  //@}

  /** @name Overridden from LinearOpBase */
  //@{

  RCP< const VectorSpaceBase<Scalar> > range() const { return space_; }

  RCP< const VectorSpaceBase<Scalar> > domain() const { return space_; }

  RCP<const LinearOpBase<Scalar> > clone() const
  {
    RCP<ScaledIdentityLinearOpWithSolve<Scalar> > op =
      rcp(new ScaledIdentityLinearOpWithSolve<Scalar>());
    op->initialize(space_, s_);
    return op;
  }
  //@}

protected:

  /** @name Overridden from LinearOpBase */
  //@{
  bool opSupportedImpl(EOpTransp /* M_trans */) const { return true; }

  void applyImpl(const EOpTransp M_trans,
                 const MultiVectorBase<Scalar>& X,
                 const Ptr<MultiVectorBase<Scalar> >& Y,
                 const Scalar alpha,
                 const Scalar beta) const
  {
    typedef Teuchos::ScalarTraits<Scalar> ST;
    Thyra::scale(beta, Y);
    if (M_trans == CONJ || M_trans == CONJTRANS)
      V_StVpV(Y, ST::conjugate(s_)*alpha, X, *Y);
    else
      V_StVpV(Y, s_*alpha, X, *Y);
  }
  //@}

  /** @name Overridden from LinearOpWithSolveBase */
  //@{
  bool solveSupportsImpl(EOpTransp /* M_trans */) const { return true; }

  bool solveSupportsNewImpl(
    EOpTransp /* M_trans */,
    const Ptr< const SolveCriteria< Scalar > > /* solveCriteria */) const
  { return true; }

  bool solveSupportsSolveMeasureTypeImpl(
    EOpTransp /* M_trans */,
     const SolveMeasureType &/* solveMeasureType */) const
  { return true; }

  SolveStatus< Scalar > solveImpl(
    const EOpTransp M_trans,
    const MultiVectorBase<Scalar>& B,
    const Ptr<MultiVectorBase<Scalar> >& X,
    const Ptr< const SolveCriteria< Scalar > > /* solveCriteria */) const
  {
    typedef Teuchos::ScalarTraits<Scalar> ST;
    assign(X, ST::zero());
    if (M_trans == CONJ || M_trans == CONJTRANS)
      V_StVpV(X, ST::one()/ST::conjugate(s_), B, *X);
    else
      V_StVpV(X, ST::one()/s_, B, *X);
    SolveStatus<Scalar> solveStatus;
    solveStatus.solveStatus = SOLVE_STATUS_CONVERGED;
    return solveStatus;
  }
  //@}

private:

  // //////////////////////////////
  // Private data members

  RCP<const VectorSpaceBase<Scalar> > space_;
  Scalar s_;

  // //////////////////////////////
  // Private member functions

  static void validateInitialize(
    const RCP<const VectorSpaceBase<Scalar> >& space) {
#ifdef TEUCHOS_DEBUG
    TEUCHOS_TEST_FOR_EXCEPT(is_null(space));
#else
    (void)space;
#endif
}

};

/** \brief Nonmember constructor function.
 *
 * \relates ScaledIdentityLinearOpWithSolve
 */
template<class Scalar>
RCP<ScaledIdentityLinearOpWithSolve<Scalar> >
scaledIdentity()
{
  return Teuchos::rcp(new ScaledIdentityLinearOpWithSolve<Scalar>());
}

/** \brief Nonmember constructor function.
 *
 * \relates ScaledIdentityLinearOpWithSolve
 */
template<class Scalar>
RCP<ScaledIdentityLinearOpWithSolve<Scalar> >
scaledIdentity(const RCP<const VectorSpaceBase<Scalar> >& space,
               const Scalar& s)
{
  RCP<ScaledIdentityLinearOpWithSolve<Scalar> >
    op = Teuchos::rcp(new ScaledIdentityLinearOpWithSolve<Scalar>());
  op->initialize(space, s);
  return op;
}

} // end namespace Thyra


#endif