Tempus_StepperOperatorSplit_decl.hpp

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// @HEADER
// ****************************************************************************
//                Tempus: Copyright (2017) Sandia Corporation
//
// Distributed under BSD 3-clause license (See accompanying file Copyright.txt)
// ****************************************************************************
// @HEADER
 
#ifndef Tempus_StepperOperatorSplit_decl_hpp
#define Tempus_StepperOperatorSplit_decl_hpp
 
#include "Tempus_config.hpp"
#include "Tempus_Stepper.hpp"
#include "Tempus_StepperOperatorSplitObserver.hpp"
 
 
namespace Tempus {
 
/** \brief OperatorSplit stepper loops through the Stepper list.
 *
 *  OperatorSplit stepper loops through the provided list of SubSteppers,
 *  and passes the SolutionHistory sequentially between them.  This is
 *  simply a first-order splitting.  It should be noted that specially
 *  constructed sequence of SubSteppers could obtain higher orders.
 *
 *  The OperatorSplit Stepper does not have any model, but the SubSteppers
 *  do.  The OperatorSplit Stepper does not have a solver either, but the
 *  SubSteppers may or may not have a solver depending if they are implicit
 *  or explicit.
 *
 *  Operator Split is only defined for one-step methods, so multi-step
 *  methods (e.g., BDF) should not be used with StepperOperatorSplit.
 */
template<class Scalar>
class StepperOperatorSplit : virtual public Tempus::Stepper<Scalar>
{
public:
 
  /// Constructor
  StepperOperatorSplit(
    std::vector<Teuchos::RCP<const Thyra::ModelEvaluator<Scalar> > > appModels,
    Teuchos::RCP<Teuchos::ParameterList> pList);
 
  /// Constructor which is setup except for models and steppers (i.e., addStepper()), and an initialize() before being used.
  StepperOperatorSplit();
 
  /// \name Basic stepper methods
  //@{
    virtual void setModel(
      const Teuchos::RCP<const Thyra::ModelEvaluator<Scalar> >& appModel);
    virtual void setNonConstModel(
      const Teuchos::RCP<Thyra::ModelEvaluator<Scalar> >& appModel);
    virtual Teuchos::RCP<const Thyra::ModelEvaluator<Scalar> >
      getModel();
 
    virtual void setSolver(std::string solverName);
    virtual void setSolver(
      Teuchos::RCP<Teuchos::ParameterList> solverPL=Teuchos::null);
    virtual void setSolver(
        Teuchos::RCP<Thyra::NonlinearSolverBase<Scalar> > solver);
    virtual Teuchos::RCP<Thyra::NonlinearSolverBase<Scalar> > getSolver() const
      { return Teuchos::null; }
    virtual void setObserver(
      Teuchos::RCP<StepperObserver<Scalar> > obs = Teuchos::null);
    virtual void setTempState(Teuchos::RCP<Tempus::SolutionState<Scalar>> state)
      { tempState_ = state; }
 
    /// Initialize during construction and after changing input parameters.
    virtual void initialize();
 
    /// Take the specified timestep, dt, and return true if successful.
    virtual void takeStep(
      const Teuchos::RCP<SolutionHistory<Scalar> >& solutionHistory);
 
    /// Pass initial guess to Newton solver (only relevant for explicit schemes)
    virtual void setInitialGuess(
      Teuchos::RCP<const Thyra::VectorBase<Scalar> > initial_guess)
      {initial_guess_ = initial_guess;}
 
   virtual std::string getStepperType() const
     { return stepperPL_->get<std::string>("Stepper Type"); }
 
    /// Get a default (initial) StepperState
    virtual Teuchos::RCP<Tempus::StepperState<Scalar> > getDefaultStepperState();
    virtual Scalar getOrder()    const
      {return stepperPL_->get<int>("Order");}
    virtual Scalar getOrderMin() const
      {return stepperPL_->get<int>("Minimum Order");}
    virtual Scalar getOrderMax() const
      {return stepperPL_->get<int>("Maximum Order");}
    virtual Scalar getInitTimeStep(
        const Teuchos::RCP<SolutionHistory<Scalar> >& solutionHistory) const
      {return std::numeric_limits<Scalar>::max();}
    virtual void setOrder   (Scalar ord)
      {stepperPL_->set<int>("Order", ord);}
    virtual void setOrderMin(Scalar ord)
      {stepperPL_->set<int>("Minimum Order", ord);}
    virtual void setOrderMax(Scalar ord)
      {stepperPL_->set<int>("Maximum Order", ord);}
 
    virtual bool isExplicit() const
    {
      bool isExplicit = false;
      typename std::vector<Teuchos::RCP<Stepper<Scalar> > >::const_iterator
        subStepperIter = subStepperList_.begin();
      for (; subStepperIter < subStepperList_.end(); subStepperIter++) {
        if ( (*subStepperIter)->isExplicit() ) isExplicit = true;
      }
      return isExplicit;
    }
    virtual bool isImplicit() const
    {
      bool isImplicit = false;
      typename std::vector<Teuchos::RCP<Stepper<Scalar> > >::const_iterator
        subStepperIter = subStepperList_.begin();
      for (; subStepperIter < subStepperList_.end(); subStepperIter++) {
        if ( (*subStepperIter)->isImplicit() ) isImplicit = true;
      }
      return isImplicit;
    }
    virtual bool isExplicitImplicit() const
      {return isExplicit() and isImplicit();}
    virtual bool isOneStepMethod()   const
    {
      bool isOneStepMethod = true;
      typename std::vector<Teuchos::RCP<Stepper<Scalar> > >::const_iterator
        subStepperIter = subStepperList_.begin();
      for (; subStepperIter < subStepperList_.end(); subStepperIter++) {
        if ( !(*subStepperIter)->isOneStepMethod() ) isOneStepMethod = false;
      }
      return isOneStepMethod;
    }
    virtual bool isMultiStepMethod() const {return !isOneStepMethod();}
  //@}
 
  /// \name ParameterList methods
  //@{
    void setParameterList(const Teuchos::RCP<Teuchos::ParameterList> & pl);
    Teuchos::RCP<Teuchos::ParameterList> getNonconstParameterList();
    Teuchos::RCP<Teuchos::ParameterList> unsetParameterList();
    Teuchos::RCP<const Teuchos::ParameterList> getValidParameters() const;
    Teuchos::RCP<Teuchos::ParameterList> getDefaultParameters() const;
  //@}
 
  /// \name Overridden from Teuchos::Describable
  //@{
    virtual std::string description() const;
    virtual void describe(Teuchos::FancyOStream        & out,
                          const Teuchos::EVerbosityLevel verbLevel) const;
  //@}
 
  virtual std::vector<Teuchos::RCP<Stepper<Scalar> > > getStepperList() const
    { return subStepperList_; }
  virtual void setStepperList(std::vector<Teuchos::RCP<Stepper<Scalar> > > sl)
    { subStepperList_ = sl; }
  virtual void addStepper(Teuchos::RCP<Stepper<Scalar> > stepper)
    { subStepperList_.push_back(stepper); }
  virtual void clearStepperList() { subStepperList_.clear(); }
  /// Take models and ParameterList and create subSteppers
  virtual void createSubSteppers(
    std::vector<Teuchos::RCP<const Thyra::ModelEvaluator<Scalar> > > appModels);
 
protected:
 
  Teuchos::RCP<Teuchos::ParameterList>                stepperPL_;
  std::vector<Teuchos::RCP<Stepper<Scalar> > >        subStepperList_;
  Teuchos::RCP<SolutionHistory<Scalar> >              OpSpSolnHistory_;
  Teuchos::RCP<SolutionState<Scalar> >                tempState_;
  Teuchos::RCP<StepperOperatorSplitObserver<Scalar> > stepperOSObserver_;
  Teuchos::RCP<const Thyra::VectorBase<Scalar> >      initial_guess_;
 
};
 
} // namespace Tempus
 
#endif // Tempus_StepperOperatorSplit_decl_hpp