Tempus_StepperExplicit_impl.hpp

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//@HEADER
// *****************************************************************************
//          Tempus: Time Integration and Sensitivity Analysis Package
//
// Copyright 2017 NTESS and the Tempus contributors.
// SPDX-License-Identifier: BSD-3-Clause
// *****************************************************************************
//@HEADER

#ifndef Tempus_StepperExplicit_impl_hpp
#define Tempus_StepperExplicit_impl_hpp

#include "Thyra_VectorStdOps.hpp"

namespace Tempus {

template <class Scalar>
void StepperExplicit<Scalar>::setModel(
    const Teuchos::RCP<const Thyra::ModelEvaluator<Scalar> >& appModel)
{
  validExplicitODE(appModel);
  appModel_ = appModel;

  inArgs_  = appModel_->getNominalValues();
  outArgs_ = appModel_->createOutArgs();
}

template <class Scalar>
void StepperExplicit<Scalar>::setInitialConditions(
    const Teuchos::RCP<SolutionHistory<Scalar> >& solutionHistory)
{
  using Teuchos::RCP;

  int numStates = solutionHistory->getNumStates();

  TEUCHOS_TEST_FOR_EXCEPTION(
      numStates < 1, std::logic_error,
      "Error - setInitialConditions() needs at least one SolutionState\n"
      "        to set the initial condition.  Number of States = "
          << numStates);

  if (numStates > 1) {
    RCP<Teuchos::FancyOStream> out = this->getOStream();
    Teuchos::OSTab ostab(out, 1, "StepperExplicit::setInitialConditions()");
    *out << "Warning -- SolutionHistory has more than one state!\n"
         << "Setting the initial conditions on the currentState.\n"
         << std::endl;
  }

  RCP<SolutionState<Scalar> > initialState = solutionHistory->getCurrentState();
  RCP<Thyra::VectorBase<Scalar> > x        = initialState->getX();
  RCP<Thyra::VectorBase<Scalar> > xDot     = initialState->getXDot();
  if (xDot == Teuchos::null) xDot = this->getStepperXDot();

  inArgs_ = appModel_->getNominalValues();
  if (this->getOrderODE() == SECOND_ORDER_ODE) {
    RCP<Thyra::VectorBase<Scalar> > initialXDot = initialState->getXDot();
    // If initialState has x and xDot set, treat them as the initial conditions.
    // Otherwise use the x and xDot from getNominalValues() as the ICs.
    TEUCHOS_TEST_FOR_EXCEPTION(
        !((x != Teuchos::null && initialXDot != Teuchos::null) ||
          (inArgs_.get_x() != Teuchos::null &&
           inArgs_.get_x_dot() != Teuchos::null)),
        std::logic_error,
        "Error - We need to set the initial conditions for x and xDot from\n"
        "        either initialState or appModel_->getNominalValues::InArgs\n"
        "        (but not from a mixture of the two).\n");
  }

  if (this->getOrderODE() == FIRST_ORDER_ODE) {
    if (x == Teuchos::null) {
      // Use x from inArgs as ICs.
      TEUCHOS_TEST_FOR_EXCEPTION(
          (x == Teuchos::null) && (inArgs_.get_x() == Teuchos::null),
          std::logic_error,
          "Error - setInitialConditions needs the ICs from the "
          "SolutionHistory\n"
          "        or getNominalValues()!\n");

      x = Teuchos::rcp_const_cast<Thyra::VectorBase<Scalar> >(inArgs_.get_x());
      initialState->setX(x);
    }
  }
  else if (this->getOrderODE() == SECOND_ORDER_ODE) {
    using Teuchos::rcp_const_cast;
    // Use the x and x_dot from getNominalValues() as the ICs.
    if (initialState->getX() == Teuchos::null ||
        initialState->getXDot() == Teuchos::null) {
      TEUCHOS_TEST_FOR_EXCEPTION(
          (inArgs_.get_x() == Teuchos::null) ||
              (inArgs_.get_x_dot() == Teuchos::null),
          std::logic_error,
          "Error - setInitialConditions() needs the ICs from the initialState\n"
          "        or getNominalValues()!\n");
      x = rcp_const_cast<Thyra::VectorBase<Scalar> >(inArgs_.get_x());
      initialState->setX(x);
      RCP<Thyra::VectorBase<Scalar> > x_dot =
          rcp_const_cast<Thyra::VectorBase<Scalar> >(inArgs_.get_x_dot());
      initialState->setXDot(x_dot);
    }
  }

  // Perform IC Consistency
  std::string icConsistency = this->getICConsistency();
  if (icConsistency == "None") {
    if (this->getOrderODE() == FIRST_ORDER_ODE) {
      if (initialState->getXDot() == Teuchos::null) {
        RCP<Teuchos::FancyOStream> out = this->getOStream();
        Teuchos::OSTab ostab(out, 1, "StepperExplicit::setInitialConditions()");
        *out << "Warning -- Requested IC consistency of 'None' but\n"
             << "           initialState does not have an xDot.\n"
             << "           Setting a 'Consistent' xDot!\n"
             << std::endl;
        auto p = Teuchos::rcp(new ExplicitODEParameters<Scalar>(0.0));
        evaluateExplicitODE(xDot, x, initialState->getTime(), p);
        initialState->setIsSynced(true);
      }
    }
    else if (this->getOrderODE() == SECOND_ORDER_ODE) {
      if (initialState->getXDotDot() == Teuchos::null) {
        RCP<Teuchos::FancyOStream> out = this->getOStream();
        Teuchos::OSTab ostab(out, 1, "StepperExplicit::setInitialConditions()");
        *out << "Warning -- Requested IC consistency of 'None' but\n"
             << "           initialState does not have an xDotDot.\n"
             << "           Setting a 'Consistent' xDotDot!\n"
             << std::endl;
        auto p = Teuchos::rcp(new ExplicitODEParameters<Scalar>(0.0));
        this->evaluateExplicitODE(this->getStepperXDotDot(initialState), x,
                                  initialState->getXDot(),
                                  initialState->getTime(), p);
        initialState->setIsSynced(true);
      }
    }
  }
  else if (icConsistency == "Zero") {
    if (this->getOrderODE() == FIRST_ORDER_ODE)
      Thyra::assign(xDot.ptr(), Scalar(0.0));
    else if (this->getOrderODE() == SECOND_ORDER_ODE)
      Thyra::assign(this->getStepperXDotDot(initialState).ptr(), Scalar(0.0));
  }
  else if (icConsistency == "App") {
    if (this->getOrderODE() == FIRST_ORDER_ODE) {
      auto x_dot = Teuchos::rcp_const_cast<Thyra::VectorBase<Scalar> >(
          inArgs_.get_x_dot());
      TEUCHOS_TEST_FOR_EXCEPTION(
          xDot == Teuchos::null, std::logic_error,
          "Error - setInitialConditions() requested 'App' for IC consistency,\n"
          "        but 'App' returned a null pointer for xDot!\n");
      Thyra::assign(xDot.ptr(), *x_dot);
    }
    else if (this->getOrderODE() == SECOND_ORDER_ODE) {
      auto xDotDot = Teuchos::rcp_const_cast<Thyra::VectorBase<Scalar> >(
          inArgs_.get_x_dot_dot());
      TEUCHOS_TEST_FOR_EXCEPTION(
          xDotDot == Teuchos::null, std::logic_error,
          "Error - setInitialConditions() requested 'App' for IC consistency,\n"
          "        but 'App' returned a null pointer for xDotDot!\n");
      Thyra::assign(this->getStepperXDotDot(initialState).ptr(), *xDotDot);
    }
  }
  else if (icConsistency == "Consistent") {
    if (this->getOrderODE() == FIRST_ORDER_ODE) {
      // Evaluate xDot = f(x,t).
      auto p = Teuchos::rcp(new ExplicitODEParameters<Scalar>(0.0));
      evaluateExplicitODE(xDot, x, initialState->getTime(), p);
    }
    else if (this->getOrderODE() == SECOND_ORDER_ODE) {
      // Evaluate xDotDot = f(x,xDot,t).
      auto p = Teuchos::rcp(new ExplicitODEParameters<Scalar>(0.0));
      this->evaluateExplicitODE(initialState->getXDotDot(), x,
                                initialState->getXDot(),
                                initialState->getTime(), p);
    }
  }
  else {
    TEUCHOS_TEST_FOR_EXCEPTION(
        true, std::logic_error,
        "Error - setInitialConditions() invalid IC consistency, '"
            << icConsistency << "'.\n");
  }

  // At this point, x, and xDot (and xDotDot) sync'ed or consistent
  // at the same time level for the initialState.
  initialState->setIsSynced(true);

  // Test for consistency.
  if (this->getICConsistencyCheck()) {
    if (this->getOrderODE() == FIRST_ORDER_ODE) {
      auto f = initialState->getX()->clone_v();
      auto p = Teuchos::rcp(new ExplicitODEParameters<Scalar>(0.0));
      evaluateExplicitODE(f, x, initialState->getTime(), p);
      Thyra::Vp_StV(f.ptr(), Scalar(-1.0), *(xDot));
      Scalar normX   = Thyra::norm(*x);
      Scalar reldiff = Scalar(0.0);
      if (normX == Scalar(0.0))
        reldiff = Thyra::norm(*f);
      else
        reldiff = Thyra::norm(*f) / normX;

      Scalar eps =
          Scalar(100.0) * std::abs(Teuchos::ScalarTraits<Scalar>::eps());
      RCP<Teuchos::FancyOStream> out = this->getOStream();
      Teuchos::OSTab ostab(out, 1, "StepperExplicit::setInitialConditions()");
      if (reldiff < eps) {
        *out << "\n---------------------------------------------------\n"
             << "Info -- Stepper = " << this->getStepperType() << "\n"
             << "  Initial condition PASSED consistency check!\n"
             << "  (||xDot-f(x,t)||/||x|| = " << reldiff << ") < "
             << "(eps = " << eps << ")" << std::endl
             << "---------------------------------------------------\n"
             << std::endl;
      }
      else {
        *out << "\n---------------------------------------------------\n"
             << "Info -- Stepper = " << this->getStepperType() << "\n"
             << "  Initial condition FAILED consistency check but continuing!\n"
             << "  (||xDot-f(x,t)||/||x|| = " << reldiff << ") > "
             << "(eps = " << eps << ")" << std::endl
             << "  ||xDot-f(x,t)|| = " << Thyra::norm(*f) << std::endl
             << "  ||x||           = " << Thyra::norm(*x) << std::endl
             << "---------------------------------------------------\n"
             << std::endl;
      }
    }
    else if (this->getOrderODE() == SECOND_ORDER_ODE) {
      auto xDotDot = initialState->getXDotDot();
      auto f       = initialState->getX()->clone_v();
      auto p       = Teuchos::rcp(new ExplicitODEParameters<Scalar>(0.0));
      this->evaluateExplicitODE(f, x, initialState->getXDot(),
                                initialState->getTime(), p);
      Thyra::Vp_StV(f.ptr(), Scalar(-1.0), *(xDotDot));
      Scalar normX   = Thyra::norm(*x);
      Scalar reldiff = Scalar(0.0);
      if (normX == Scalar(0.0))
        reldiff = Thyra::norm(*f);
      else
        reldiff = Thyra::norm(*f) / normX;

      Scalar eps =
          Scalar(100.0) * std::abs(Teuchos::ScalarTraits<Scalar>::eps());
      RCP<Teuchos::FancyOStream> out = this->getOStream();
      Teuchos::OSTab ostab(out, 1, "StepperExplicit::setInitialConditions()");
      if (reldiff < eps) {
        *out << "\n---------------------------------------------------\n"
             << "Info -- Stepper = " << this->getStepperType() << "\n"
             << "  Initial condition PASSED consistency check!\n"
             << "  (||xDotDot-f(x,xDot,t)||/||x|| = " << reldiff << ") > "
             << "(eps = " << eps << ")" << std::endl
             << "---------------------------------------------------\n"
             << std::endl;
      }
      else {
        *out << "\n---------------------------------------------------\n"
             << "Info -- Stepper = " << this->getStepperType() << "\n"
             << "Initial condition FAILED consistency check but continuing!\n"
             << "  (||xDotDot-f(x,xDot,t)||/||x|| = " << reldiff << ") > "
             << "(eps = " << eps << ")" << std::endl
             << "  ||xDotDot-f(x,xDot,t)|| = " << Thyra::norm(*f) << std::endl
             << "  ||x||                   = " << Thyra::norm(*x) << std::endl
             << "---------------------------------------------------\n"
             << std::endl;
      }
    }
  }
}

template <class Scalar>
void StepperExplicit<Scalar>::setSolver(
    Teuchos::RCP<Thyra::NonlinearSolverBase<Scalar> > /* solver */)
{
  Teuchos::RCP<Teuchos::FancyOStream> out = this->getOStream();
  Teuchos::OSTab ostab(out, 1, "StepperExplicit::setSolver()");
  *out << "Warning -- No solver to set for StepperExplicit "
       << "(i.e., explicit method).\n"
       << std::endl;
  return;
}
template <class Scalar>
void StepperExplicit<Scalar>::evaluateExplicitODE(
    Teuchos::RCP<Thyra::VectorBase<Scalar> > xDot,
    Teuchos::RCP<const Thyra::VectorBase<Scalar> > x, const Scalar time,
    const Teuchos::RCP<ExplicitODEParameters<Scalar> >& p)
{
  typedef Thyra::ModelEvaluatorBase MEB;

  inArgs_.set_x(x);
  if (inArgs_.supports(MEB::IN_ARG_t)) inArgs_.set_t(time);
  if (inArgs_.supports(MEB::IN_ARG_step_size))
    inArgs_.set_step_size(p->timeStepSize_);
  if (inArgs_.supports(MEB::IN_ARG_stage_number))
    inArgs_.set_stage_number(p->stageNumber_);

  // For model evaluators whose state function f(x, xDot, t) describes
  // an implicit ODE, and which accept an optional xDot input argument,
  // make sure the latter is set to null in order to request the evaluation
  // of a state function corresponding to the explicit ODE formulation
  // xDot = f(x, t).
  if (inArgs_.supports(MEB::IN_ARG_x_dot)) inArgs_.set_x_dot(Teuchos::null);

  outArgs_.set_f(xDot);

  appModel_->evalModel(inArgs_, outArgs_);
}

template <class Scalar>
void StepperExplicit<Scalar>::evaluateExplicitODE(
    Teuchos::RCP<Thyra::VectorBase<Scalar> > xDotDot,
    Teuchos::RCP<const Thyra::VectorBase<Scalar> > x,
    Teuchos::RCP<const Thyra::VectorBase<Scalar> > xDot, const Scalar time,
    const Teuchos::RCP<ExplicitODEParameters<Scalar> >& p)
{
  typedef Thyra::ModelEvaluatorBase MEB;

  inArgs_.set_x(x);
  if (inArgs_.supports(MEB::IN_ARG_x_dot)) inArgs_.set_x_dot(xDot);
  if (inArgs_.supports(MEB::IN_ARG_t)) inArgs_.set_t(time);
  if (inArgs_.supports(MEB::IN_ARG_step_size))
    inArgs_.set_step_size(p->timeStepSize_);
  if (inArgs_.supports(MEB::IN_ARG_stage_number))
    inArgs_.set_stage_number(p->stageNumber_);

  // For model evaluators whose state function f(x, xDot, xDotDot, t) describes
  // an implicit ODE, and which accept an optional xDotDot input argument,
  // make sure the latter is set to null in order to request the evaluation
  // of a state function corresponding to the explicit ODE formulation
  // xDotDot = f(x, xDot, t).
  if (inArgs_.supports(MEB::IN_ARG_x_dot_dot))
    inArgs_.set_x_dot_dot(Teuchos::null);

  outArgs_.set_f(xDotDot);

  appModel_->evalModel(inArgs_, outArgs_);
}

template <class Scalar>
void StepperExplicit<Scalar>::describe(
    Teuchos::FancyOStream& out, const Teuchos::EVerbosityLevel verbLevel) const
{
  auto l_out = Teuchos::fancyOStream(out.getOStream());
  Teuchos::OSTab ostab(*l_out, 2, this->description());
  l_out->setOutputToRootOnly(0);

  *l_out << "--- StepperExplicit ---\n"
         << "  appModel_         = " << appModel_ << std::endl
         << "  inArgs_           = " << inArgs_ << std::endl
         << "  outArgs_          = " << outArgs_ << std::endl;
}

template <class Scalar>
bool StepperExplicit<Scalar>::isValidSetup(Teuchos::FancyOStream& out) const
{
  out.setOutputToRootOnly(0);
  bool isValidSetup = true;

  if (appModel_ == Teuchos::null) {
    isValidSetup = false;
    out << "The application ModelEvaluator is not set!\n";
  }

  return isValidSetup;
}

template <class Scalar>
void StepperExplicit<Scalar>::setStepperExplicitValues(
    Teuchos::RCP<Teuchos::ParameterList> pl)
{
  if (pl != Teuchos::null) {
    pl->validateParametersAndSetDefaults(*this->getValidParameters(), 0);
    this->setStepperValues(pl);
  }
}

}  // namespace Tempus
#endif  // Tempus_StepperExplicit_impl_hpp