Tempus_StepperRKBase.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_StepperRKBase_hpp
#define Tempus_StepperRKBase_hpp

#include "Thyra_VectorBase.hpp"

#include "Tempus_config.hpp"
#include "Tempus_Stepper.hpp"
#include "Tempus_RKButcherTableau.hpp"
#include "Tempus_StepperRKAppAction.hpp"
#include "Tempus_StepperRKModifierDefault.hpp"


namespace Tempus {

template<class Scalar>
class StepperRKBase : virtual public Tempus::Stepper<Scalar>
{

public:

  virtual Teuchos::RCP<const RKButcherTableau<Scalar> > getTableau() const
  { return tableau_; }

  virtual Scalar getOrder()    const{return getTableau()->order();}
  virtual Scalar getOrderMin() const{return getTableau()->orderMin();}
  virtual Scalar getOrderMax() const{return getTableau()->orderMax();}
  virtual int getNumberOfStages() const {return getTableau()->numStages();}

  virtual int getStageNumber() const { return stageNumber_; }
  virtual void setStageNumber(int s) { stageNumber_ = s; }

  virtual void setUseEmbedded(bool a) { useEmbedded_ = a; }
  virtual bool getUseEmbedded() const { return useEmbedded_; }

  virtual void setAppAction(Teuchos::RCP<StepperRKAppAction<Scalar> > appAction)
  {
    if (appAction == Teuchos::null) {
      // Create default appAction
      stepperRKAppAction_ =
        Teuchos::rcp(new StepperRKModifierDefault<Scalar>());
    } else {
      stepperRKAppAction_ = appAction;
    }
    this->isInitialized_ = false;
  }

  virtual Teuchos::RCP<StepperRKAppAction<Scalar> > getAppAction() const
    { return stepperRKAppAction_; }

  virtual void setStepperRKValues(Teuchos::RCP<Teuchos::ParameterList> pl)
  {
    if (pl != Teuchos::null) {
      pl->validateParametersAndSetDefaults(*this->getValidParameters());
      this->setStepperValues(pl);
      if (pl->isParameter("Use Embedded"))
        this->setUseEmbedded(pl->get<bool>("Use Embedded"));
    }
  }

  virtual Teuchos::RCP<RKButcherTableau<Scalar> >
  createTableau(Teuchos::RCP<Teuchos::ParameterList> pl)
  {
    TEUCHOS_TEST_FOR_EXCEPTION(pl == Teuchos::null,std::runtime_error,
      "Error parsing general tableau.  ParameterList is null.\n");

    Teuchos::RCP<RKButcherTableau<Scalar> > tableau;

    Teuchos::RCP<Teuchos::ParameterList> tableauPL = sublist(pl,"Tableau",true);
    std::size_t numStages = 0;
    int order = tableauPL->get<int>("order");
    Teuchos::SerialDenseMatrix<int,Scalar> A;
    Teuchos::SerialDenseVector<int,Scalar> b;
    Teuchos::SerialDenseVector<int,Scalar> c;
    Teuchos::SerialDenseVector<int,Scalar> bstar;

    // read in the A matrix
    {
      std::vector<std::string> A_row_tokens;
      Tempus::StringTokenizer(A_row_tokens, tableauPL->get<std::string>("A"),
                              ";",true);

      // this is the only place where numStages is set
      numStages = A_row_tokens.size();

      // allocate the matrix
      A.shape(Teuchos::as<int>(numStages),Teuchos::as<int>(numStages));

      // fill the rows
      for(std::size_t row=0;row<numStages;row++) {
        // parse the row (tokenize on space)
        std::vector<std::string> tokens;
        Tempus::StringTokenizer(tokens,A_row_tokens[row]," ",true);

        std::vector<double> values;
        Tempus::TokensToDoubles(values,tokens);

        TEUCHOS_TEST_FOR_EXCEPTION(values.size()!=numStages,std::runtime_error,
          "Error parsing A matrix, wrong number of stages in row "
          << row << ".\n");

        for(std::size_t col=0;col<numStages;col++)
          A(row,col) = values[col];
      }
    }

    // size b and c vectors
    b.size(Teuchos::as<int>(numStages));
    c.size(Teuchos::as<int>(numStages));

    // read in the b vector
    {
      std::vector<std::string> tokens;
      Tempus::StringTokenizer(tokens,tableauPL->get<std::string>("b")," ",true);
      std::vector<double> values;
      Tempus::TokensToDoubles(values,tokens);

      TEUCHOS_TEST_FOR_EXCEPTION(values.size()!=numStages,std::runtime_error,
        "Error parsing b vector, wrong number of stages.\n");

      for(std::size_t i=0;i<numStages;i++)
        b(i) = values[i];
    }

    // read in the c vector
    {
      std::vector<std::string> tokens;
      Tempus::StringTokenizer(tokens,tableauPL->get<std::string>("c")," ",true);
      std::vector<double> values;
      Tempus::TokensToDoubles(values,tokens);

      TEUCHOS_TEST_FOR_EXCEPTION(values.size()!=numStages,std::runtime_error,
        "Error parsing c vector, wrong number of stages.\n");

      for(std::size_t i=0;i<numStages;i++)
        c(i) = values[i];
    }

    if (tableauPL->isParameter("bstar") &&
        tableauPL->get<std::string>("bstar") != "") {
      bstar.size(Teuchos::as<int>(numStages));
      // read in the bstar vector
      {
        std::vector<std::string> tokens;
        Tempus::StringTokenizer(
          tokens, tableauPL->get<std::string>("bstar"), " ", true);
        std::vector<double> values;
        Tempus::TokensToDoubles(values,tokens);

        TEUCHOS_TEST_FOR_EXCEPTION(values.size()!=numStages,std::runtime_error,
          "Error parsing bstar vector, wrong number of stages.\n"
          "      Number of RK stages    = " << numStages << "\n"
          "      Number of bstar values = " << values.size() << "\n");

        for(std::size_t i=0;i<numStages;i++)
          bstar(i) = values[i];
      }
      tableau = rcp(new RKButcherTableau<Scalar>(
        "From ParameterList",A,b,c,order,order,order,bstar));
    } else {
      tableau = rcp(new RKButcherTableau<Scalar>(
        "From ParameterList",A,b,c,order,order,order));
    }
    return tableau;
  }


protected:

  Teuchos::RCP<RKButcherTableau<Scalar> >   tableau_;

  // For Embedded RK
  bool useEmbedded_;
  Teuchos::RCP<Thyra::VectorBase<Scalar> >  ee_;
  Teuchos::RCP<Thyra::VectorBase<Scalar> >  abs_u0;
  Teuchos::RCP<Thyra::VectorBase<Scalar> >  abs_u;
  Teuchos::RCP<Thyra::VectorBase<Scalar> >  sc;

  int stageNumber_;
  Teuchos::RCP<StepperRKAppAction<Scalar> > stepperRKAppAction_;

};

} // namespace Tempus

#endif // Tempus_StepperRKBase_hpp