Tempus_UnitTest_IMEX_RK.cpp

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

#include "Tempus_UnitTest_RK_Utils.hpp"

#include "Tempus_StepperRKButcherTableau.hpp"

#include "../TestModels/DahlquistTestModel.hpp"
#include "../TestModels/VanDerPol_IMEX_ExplicitModel.hpp"
#include "../TestModels/VanDerPol_IMEX_ImplicitModel.hpp"


namespace Tempus_Unit_Test {

using Teuchos::RCP;
using Teuchos::rcp;
using Teuchos::rcp_const_cast;
using Teuchos::rcp_dynamic_cast;
using Teuchos::ParameterList;
using Teuchos::sublist;

using Tempus::StepperFactory;
using Tempus::StepperExplicitRK;


// ************************************************************
// ************************************************************
TEUCHOS_UNIT_TEST(IMEX_RK, Default_Construction)
{
  // Setup the IMEX Pair ModelEvaluator
  auto explicitModel = rcp(new Tempus_Test::VanDerPol_IMEX_ExplicitModel<double>());
  auto implicitModel = rcp(new Tempus_Test::VanDerPol_IMEX_ImplicitModel<double>());
  auto model = rcp(new Tempus::WrapperModelEvaluatorPairIMEX_Basic<double>(
                                             explicitModel, implicitModel));

  // Default construction.
  auto stepper = rcp(new Tempus::StepperIMEX_RK<double>());
  stepper->setModel(model);
  stepper->initialize();
  TEUCHOS_TEST_FOR_EXCEPT(!stepper->isInitialized());

  // Default values for construction.
  auto modifier  = rcp(new Tempus::StepperRKModifierDefault<double>());
  auto modifierX = rcp(new Tempus::StepperRKModifierXDefault<double>());
  auto observer  = rcp(new Tempus::StepperRKObserverDefault<double>());
  auto solver = rcp(new Thyra::NOXNonlinearSolver());
  solver->setParameterList(Tempus::defaultSolverParameters());

  bool useFSAL              = stepper->getUseFSAL();
  std::string ICConsistency = stepper->getICConsistency();
  bool ICConsistencyCheck   = stepper->getICConsistencyCheck();
  bool zeroInitialGuess     = stepper->getZeroInitialGuess();
  std::string stepperType   = "IMEX RK SSP2";
  auto stepperERK = Teuchos::rcp(new Tempus::StepperERK_Trapezoidal<double>());
  auto explicitTableau      = stepperERK->getTableau();
  auto stepperSDIRK = Teuchos::rcp(new Tempus::StepperSDIRK_2Stage3rdOrder<double>());
  auto implicitTableau      = stepperSDIRK->getTableau();
  int order                 = 2;


  // Test the set functions.
  stepper->setAppAction(modifier);                     stepper->initialize();  TEUCHOS_TEST_FOR_EXCEPT(!stepper->isInitialized());
  stepper->setAppAction(modifierX);                    stepper->initialize();  TEUCHOS_TEST_FOR_EXCEPT(!stepper->isInitialized());
  stepper->setAppAction(observer);                     stepper->initialize();  TEUCHOS_TEST_FOR_EXCEPT(!stepper->isInitialized());
  stepper->setSolver(solver);                          stepper->initialize();  TEUCHOS_TEST_FOR_EXCEPT(!stepper->isInitialized());
  stepper->setUseFSAL(useFSAL);                        stepper->initialize();  TEUCHOS_TEST_FOR_EXCEPT(!stepper->isInitialized());
  stepper->setICConsistency(ICConsistency);            stepper->initialize();  TEUCHOS_TEST_FOR_EXCEPT(!stepper->isInitialized());
  stepper->setICConsistencyCheck(ICConsistencyCheck);  stepper->initialize();  TEUCHOS_TEST_FOR_EXCEPT(!stepper->isInitialized());
  stepper->setZeroInitialGuess(zeroInitialGuess);      stepper->initialize();  TEUCHOS_TEST_FOR_EXCEPT(!stepper->isInitialized());

  stepper->setStepperName(stepperType);                stepper->initialize();  TEUCHOS_TEST_FOR_EXCEPT(!stepper->isInitialized());
  stepper->setExplicitTableau(explicitTableau);        stepper->initialize();  TEUCHOS_TEST_FOR_EXCEPT(!stepper->isInitialized());
  stepper->setImplicitTableau(implicitTableau);        stepper->initialize();  TEUCHOS_TEST_FOR_EXCEPT(!stepper->isInitialized());
  stepper->setOrder(order);                            stepper->initialize();  TEUCHOS_TEST_FOR_EXCEPT(!stepper->isInitialized());

  TEUCHOS_TEST_FOR_EXCEPT(explicitTableau != stepper->getTableau());
  TEUCHOS_TEST_FOR_EXCEPT(explicitTableau != stepper->getExplicitTableau());
  TEUCHOS_TEST_FOR_EXCEPT(implicitTableau != stepper->getImplicitTableau());

  // Full argument list construction.
  stepper = rcp(new Tempus::StepperIMEX_RK<double>(
    model, solver, useFSAL, ICConsistency, ICConsistencyCheck,
    zeroInitialGuess, modifier, stepperType, explicitTableau,
    implicitTableau, order));
  TEUCHOS_TEST_FOR_EXCEPT(!stepper->isInitialized());

  // Test stepper properties.
  TEUCHOS_ASSERT(stepper->getOrder() == 2);
}


// ************************************************************
// ************************************************************
TEUCHOS_UNIT_TEST(IMEX_RK, StepperFactory_Construction)
{
  // Setup the IMEX Pair ModelEvaluator
  auto explicitModel = rcp(new Tempus_Test::VanDerPol_IMEX_ExplicitModel<double>());
  auto implicitModel = rcp(new Tempus_Test::VanDerPol_IMEX_ImplicitModel<double>());
  auto model = rcp(new Tempus::WrapperModelEvaluatorPairIMEX_Basic<double>(
                                             explicitModel, implicitModel));

  testFactoryConstruction("IMEX RK SSP2", model);
}


// ************************************************************
// ************************************************************
TEUCHOS_UNIT_TEST(IMEX_RK, StepperFactory_Construction_General_wo_Parameterlist)
{
   // Setup the IMEX Pair ModelEvaluator
  auto explicitModel = rcp(new Tempus_Test::VanDerPol_IMEX_ExplicitModel<double>());
  auto implicitModel = rcp(new Tempus_Test::VanDerPol_IMEX_ImplicitModel<double>());
  auto model = rcp(new Tempus::WrapperModelEvaluatorPairIMEX_Basic<double>(
                                             explicitModel, implicitModel));

  RCP<StepperFactory<double> > sf = Teuchos::rcp(new StepperFactory<double>());

  auto stepper = sf->createStepper("General IMEX RK", model);
  TEUCHOS_TEST_FOR_EXCEPT(!stepper->isInitialized());
}


// ************************************************************
// ************************************************************
TEUCHOS_UNIT_TEST(IMEX_RK, StepperFactory_Construction_General_wo_Parameterlist_Model)
{
   // Setup the IMEX Pair ModelEvaluator
  auto explicitModel = rcp(new Tempus_Test::VanDerPol_IMEX_ExplicitModel<double>());
  auto implicitModel = rcp(new Tempus_Test::VanDerPol_IMEX_ImplicitModel<double>());
  auto model = rcp(new Tempus::WrapperModelEvaluatorPairIMEX_Basic<double>(
                                             explicitModel, implicitModel));

  RCP<StepperFactory<double> > sf = Teuchos::rcp(new StepperFactory<double>());

  auto stepper = sf->createStepper("General IMEX RK");
  stepper->setModel(model);
  stepper->initialize();
  TEUCHOS_TEST_FOR_EXCEPT(!stepper->isInitialized());
}


// ************************************************************
// ************************************************************
TEUCHOS_UNIT_TEST(IMEX_RK, AppAction)
{
  auto stepper = rcp(new Tempus::StepperIMEX_RK<double>());
  // Setup the IMEX Pair ModelEvaluator
  auto explicitModel = rcp(new Tempus_Test::VanDerPol_IMEX_ExplicitModel<double>());
  auto implicitModel = rcp(new Tempus_Test::VanDerPol_IMEX_ImplicitModel<double>());
  auto model = rcp(new Tempus::WrapperModelEvaluatorPairIMEX_Basic<double>(
                                             explicitModel, implicitModel));

  testRKAppAction(stepper, model, out, success);
}



class StepperRKModifierIMEX_TrapezoidaTest
  : virtual public Tempus::StepperRKModifierBase<double>
{
  public:

    StepperRKModifierIMEX_TrapezoidaTest(Teuchos::FancyOStream &Out, bool &Success)
      : out(Out), success(Success)
    {}

    // FSAL
    virtual ~StepperRKModifierIMEX_TrapezoidaTest(){}

    virtual void modify(
        Teuchos::RCP<Tempus::SolutionHistory<double> > sh,
        Teuchos::RCP<Tempus::StepperRKBase<double> > stepper,
        const typename Tempus::StepperRKAppAction<double>::ACTION_LOCATION actLoc)
    {
      const double relTol = 1.0e-14;
      auto stepper_imex = Teuchos::rcp_dynamic_cast<const Tempus::StepperIMEX_RK<double>>(stepper, true);
      auto stageNumber = stepper->getStageNumber();
      Teuchos::SerialDenseVector<int,double> c = stepper_imex->getTableau()->c();
      Teuchos::SerialDenseVector<int,double> chat = stepper_imex->getImplicitTableau()->c();

      auto currentState   = sh->getCurrentState();
      auto workingState   = sh->getWorkingState();
      const double dt     = workingState->getTimeStep();
      double time = currentState->getTime();
      double imp_time = time;
      if (stageNumber >= 0) {
        time     += c(stageNumber)*dt;
        imp_time += chat(stageNumber)*dt;
      }

      auto x    = workingState->getX();
      auto xDot = workingState->getXDot();
      if (xDot == Teuchos::null) xDot = stepper->getStepperXDot();

      switch (actLoc) {
        case StepperRKAppAction<double>::BEGIN_STEP:
          {
            {

              auto imex_me = Teuchos::rcp_dynamic_cast<const Tempus::WrapperModelEvaluatorPairIMEX_Basic<double>>(stepper->getModel(), true);
              auto explicitModel = Teuchos::rcp_dynamic_cast<const Tempus_Test::DahlquistTestModel<double> > (imex_me->getExplicitModel(), true);
              auto implicitModel = Teuchos::rcp_dynamic_cast<const Tempus_Test::DahlquistTestModel<double> > (imex_me->getImplicitModel(), true);

              TEST_FLOATING_EQUALITY(explicitModel->getLambda(), 1.0, relTol);
              TEST_FLOATING_EQUALITY(implicitModel->getLambda(), 2.0, relTol);
            }
            TEST_FLOATING_EQUALITY(dt, 1.0, relTol);

            const double x_0    = get_ele(*(x), 0);
            TEST_FLOATING_EQUALITY(x_0,    1.0, relTol);
            TEST_ASSERT(std::abs(time) < relTol);
            TEST_ASSERT(std::abs(imp_time) < relTol);
            TEST_FLOATING_EQUALITY(dt,      1.0, relTol);
            TEST_COMPARE(stageNumber, ==, -1);
            break;
          }
        case StepperRKAppAction<double>::BEGIN_STAGE:
        case StepperRKAppAction<double>::BEFORE_SOLVE:
          {
            const double X_i = get_ele(*(x), 0);
            const double f_i = get_ele(*(xDot), 0);

            if (stageNumber == 0) {
              TEST_FLOATING_EQUALITY(X_i      , 1.0                 , relTol); // 1
              TEST_FLOATING_EQUALITY(f_i      , 1.0                 , relTol); // 1
              TEST_FLOATING_EQUALITY(imp_time , 0.78867513459481275 , relTol); // 1
              TEST_ASSERT(std::abs(time) < relTol);
            } else if (stageNumber == 1) {
              TEST_FLOATING_EQUALITY(X_i      , -std::sqrt(3)       , relTol); // -sqrt(3)
              TEST_FLOATING_EQUALITY(f_i      , 1.0                 , relTol); // 1
              TEST_FLOATING_EQUALITY(time     , 1.0                 , relTol);
              TEST_FLOATING_EQUALITY(imp_time , 0.21132486540518725 , relTol); // 1
            } else {
              TEUCHOS_TEST_FOR_EXCEPT( !(-1 < stageNumber && stageNumber < 2));
            }

            break;
          }
        case StepperRKAppAction<double>::AFTER_SOLVE:
        case StepperRKAppAction<double>::BEFORE_EXPLICIT_EVAL:
        case StepperRKAppAction<double>::END_STAGE:
          {
            const double X_i = get_ele(*(x), 0);
            const double f_i = get_ele(*(xDot), 0);

            if (stageNumber == 0) {
              // X_i = 1, f_1 = 0
              TEST_FLOATING_EQUALITY(X_i, -std::sqrt(3), relTol); // -sqrt(3)
              TEST_FLOATING_EQUALITY(f_i,     1.0, relTol); // 1
              TEST_FLOATING_EQUALITY(imp_time , 0.78867513459481275 , relTol); // 1
              TEST_ASSERT(std::abs(time) < relTol);
            } else if (stageNumber == 1) {
              // X_i = , f_i =
              TEST_FLOATING_EQUALITY(X_i,    3.0 - 3.0*std::sqrt(3.0), relTol); // -3sqrt(3) - 3
              TEST_FLOATING_EQUALITY(f_i,    1.0, relTol); // 1
              TEST_FLOATING_EQUALITY(time,    1.0, relTol);
            } else {
              TEUCHOS_TEST_FOR_EXCEPT( !(-1 < stageNumber && stageNumber < 2));
            }

            break;
          }
        case StepperRKAppAction<double>::END_STEP:
          {
            const double x_1 = get_ele(*(x), 0);
            time = workingState->getTime();
            TEST_FLOATING_EQUALITY(x_1,  -(6.0*std::sqrt(3) - 11.0/2.0), relTol);   // -( 6sqrt(3) - 11/2)
            TEST_FLOATING_EQUALITY(time,     1.0, relTol);
            TEST_FLOATING_EQUALITY(dt,       1.0, relTol);
            TEST_COMPARE(stageNumber, ==, -1);

          }

      }


    }

  private:

    Teuchos::FancyOStream & out;
    bool & success;
};

// ************************************************************
// ************************************************************
TEUCHOS_UNIT_TEST(IMEX_RK, IMEX_RK_Modifier)
{

  Teuchos::RCP<const Thyra::ModelEvaluator<double> > explicitModel = rcp(new Tempus_Test::DahlquistTestModel<double>(1.0, true));
  Teuchos::RCP<const Thyra::ModelEvaluator<double> > implicitModel = rcp(new Tempus_Test::DahlquistTestModel<double>(2.0, true));

  auto model = rcp(new Tempus::WrapperModelEvaluatorPairIMEX_Basic<double>(
                                             explicitModel, implicitModel));

  auto modifier = rcp(new StepperRKModifierIMEX_TrapezoidaTest(out, success));


  // Default construction.
  auto stepper = rcp(new Tempus::StepperIMEX_RK<double>());
  stepper->setModel(model);

  // Default values for construction.
  auto solver = rcp(new Thyra::NOXNonlinearSolver());
  solver->setParameterList(Tempus::defaultSolverParameters());

  bool useFSAL              = stepper->getUseFSAL();
  std::string ICConsistency = stepper->getICConsistency();
  bool ICConsistencyCheck   = stepper->getICConsistencyCheck();
  bool zeroInitialGuess     = stepper->getZeroInitialGuess();
  std::string stepperType   = "IMEX RK SSP2";
  auto stepperERK = Teuchos::rcp(new Tempus::StepperERK_Trapezoidal<double>());
  auto explicitTableau      = stepperERK->getTableau();
  auto stepperSDIRK = Teuchos::rcp(new Tempus::StepperSDIRK_2Stage3rdOrder<double>());
  auto implicitTableau      = stepperSDIRK->getTableau();
  int order                 = 2;

  stepper->setStepperName(stepperType);
  stepper->setExplicitTableau(explicitTableau);
  stepper->setImplicitTableau(implicitTableau);
  stepper->setOrder(order);
  stepper->setSolver(solver);
  stepper->setUseFSAL(useFSAL);
  stepper->setICConsistency(ICConsistency);
  stepper->setICConsistencyCheck(ICConsistencyCheck);
  stepper->setZeroInitialGuess(zeroInitialGuess);

  stepper->setModel(model);
  stepper->setAppAction(modifier);
  stepper->setUseFSAL(false);
  stepper->initialize();

  // Create a SolutionHistory.
  auto solutionHistory = Tempus::createSolutionHistoryME(explicitModel);

  stepper->setInitialConditions(solutionHistory);
  solutionHistory->initWorkingState();
  double dt = 1.0;
  solutionHistory->getWorkingState()->setTimeStep(dt);
  solutionHistory->getWorkingState()->setTime(dt);
  stepper->takeStep(solutionHistory);

  // Test stepper properties.
  TEUCHOS_ASSERT(stepper->getOrder() == 2);
}



} // namespace Tempus_Unit_Test