Tempus_TimeStepControl_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_TimeStepControl_impl_hpp
#define Tempus_TimeStepControl_impl_hpp

#include "Teuchos_TimeMonitor.hpp"

#include "Tempus_TimeStepControlStrategyConstant.hpp"
#include "Tempus_TimeStepControlStrategyComposite.hpp"
#include "Tempus_TimeStepControlStrategyBasicVS.hpp"
#include "Tempus_TimeStepControlStrategyIntegralController.hpp"
#include "Tempus_TimeEventRange.hpp"
#include "Tempus_TimeEventRangeIndex.hpp"
#include "Tempus_TimeEventList.hpp"
#include "Tempus_TimeEventListIndex.hpp"

namespace Tempus {

template <class Scalar>
TimeStepControl<Scalar>::TimeStepControl()
  : isInitialized_(false),
    initTime_(0.0),
    finalTime_(1.0e+99),
    minTimeStep_(0.0),
    initTimeStep_(1.0e+99),
    maxTimeStep_(1.0e+99),
    initIndex_(0),
    finalIndex_(1000000),
    maxAbsError_(1.0e-08),
    maxRelError_(1.0e-08),
    maxFailures_(10),
    maxConsecFailures_(5),
    numTimeSteps_(-1),
    printDtChanges_(true),
    teAdjustedDt_(false),
    dtAfterTimeEvent_(0.0)
{
  setTimeStepControlStrategy();
  setTimeEvents();
  this->initialize();
}

template <class Scalar>
TimeStepControl<Scalar>::TimeStepControl(
    Scalar initTime, Scalar finalTime, Scalar minTimeStep, Scalar initTimeStep,
    Scalar maxTimeStep, int initIndex, int finalIndex, Scalar maxAbsError,
    Scalar maxRelError, int maxFailures, int maxConsecFailures,
    int numTimeSteps, bool printDtChanges, bool outputExactly,
    std::vector<int> outputIndices, std::vector<Scalar> outputTimes,
    int outputIndexInterval, Scalar outputTimeInterval,
    Teuchos::RCP<TimeEventComposite<Scalar>> timeEvent,
    Teuchos::RCP<TimeStepControlStrategy<Scalar>> stepControlStrategy)
  : isInitialized_(false),
    initTime_(initTime),
    finalTime_(finalTime),
    minTimeStep_(minTimeStep),
    initTimeStep_(initTimeStep),
    maxTimeStep_(maxTimeStep),
    initIndex_(initIndex),
    finalIndex_(finalIndex),
    maxAbsError_(maxAbsError),
    maxRelError_(maxRelError),
    maxFailures_(maxFailures),
    maxConsecFailures_(maxConsecFailures),
    printDtChanges_(printDtChanges),
    teAdjustedDt_(false),
    dtAfterTimeEvent_(0.0)
{
  using Teuchos::rcp;

  setTimeStepControlStrategy(stepControlStrategy);
  setNumTimeSteps(numTimeSteps);

  auto tec = rcp(new TimeEventComposite<Scalar>());
  tec->setName("Time Step Control Events");
  auto tes = timeEvent->getTimeEvents();
  for (auto& e : tes) tec->add(e);

  // Add a range of times.
  auto teRange =
      rcp(new TimeEventRange<Scalar>(initTime, finalTime, outputTimeInterval,
                                     "Output Time Interval", outputExactly));
  tec->add(teRange);

  // Add a list of times.
  if (!outputTimes.empty())
    tec->add(rcp(new TimeEventList<Scalar>(outputTimes, "Output Time List",
                                           outputExactly)));

  // Add a range of indices.
  tec->add(rcp(new TimeEventRangeIndex<Scalar>(
      initIndex, finalIndex, outputIndexInterval, "Output Index Interval")));

  // Add a list of indices.
  if (!outputTimes.empty())
    tec->add(rcp(
        new TimeEventListIndex<Scalar>(outputIndices, "Output Index List")));

  setTimeEvents(tec);

  this->initialize();
}

template <class Scalar>
void TimeStepControl<Scalar>::initialize() const
{
  TEUCHOS_TEST_FOR_EXCEPTION(
      (getInitTime() > getFinalTime()), std::logic_error,
      "Error - Inconsistent time range.\n"
      "    (timeMin = "
          << getInitTime() << ") > (timeMax = " << getFinalTime() << ")\n");

  TEUCHOS_TEST_FOR_EXCEPTION(
      (getMinTimeStep() < Teuchos::ScalarTraits<Scalar>::zero()),
      std::logic_error,
      "Error - Negative minimum time step.  dtMin = " << getMinTimeStep() << ")\n");
  TEUCHOS_TEST_FOR_EXCEPTION(
      (getMaxTimeStep() < Teuchos::ScalarTraits<Scalar>::zero()),
      std::logic_error,
      "Error - Negative maximum time step.  dtMax = " << getMaxTimeStep() << ")\n");
  TEUCHOS_TEST_FOR_EXCEPTION(
      (getMinTimeStep() > getMaxTimeStep()), std::logic_error,
      "Error - Inconsistent time step range.\n"
          << "  (dtMin = "
          << getMinTimeStep() << ") > (dtMax = " << getMaxTimeStep() << ")\n");
  TEUCHOS_TEST_FOR_EXCEPTION(
      (getInitTimeStep() < Teuchos::ScalarTraits<Scalar>::zero()),
      std::logic_error,
      "Error - Negative initial time step.  dtInit = " << getInitTimeStep() << ")\n");
  TEUCHOS_TEST_FOR_EXCEPTION((getInitTimeStep() < getMinTimeStep() ||
                              getInitTimeStep() > getMaxTimeStep()),
                             std::out_of_range,
                             "Error - Initial time step is out of range.\n"
                                 << "    [dtMin, dtMax] = [" << getMinTimeStep()
                                 << ", " << getMaxTimeStep() << "]\n"
                                 << "    dtInit = " << getInitTimeStep()
                                 << "\n");

  TEUCHOS_TEST_FOR_EXCEPTION(
      (getInitIndex() > getFinalIndex()), std::logic_error,
      "Error - Inconsistent time index range.\n"
      "  (iStepMin = "
          << getInitIndex() << ") > (iStepMax = " << getFinalIndex() << ")\n");

  TEUCHOS_TEST_FOR_EXCEPTION(
      (getMaxAbsError() < Teuchos::ScalarTraits<Scalar>::zero()),
      std::logic_error,
      "Error - Negative maximum time step.  errorMaxAbs = " << getMaxAbsError() << ")\n");
  TEUCHOS_TEST_FOR_EXCEPTION(
      (getMaxRelError() < Teuchos::ScalarTraits<Scalar>::zero()),
      std::logic_error,
      "Error - Negative maximum time step.  errorMaxRel = " << getMaxRelError() << ")\n");

  TEUCHOS_TEST_FOR_EXCEPTION((stepControlStrategy_ == Teuchos::null),
                             std::logic_error, "Error - Strategy is unset!\n");

  stepControlStrategy_->initialize();

  TEUCHOS_TEST_FOR_EXCEPTION(
      (getStepType() != "Constant" && getStepType() != "Variable"),
      std::out_of_range,
      "Error - 'Step Type' does not equal one of these:\n"
          << "  'Constant' - Integrator will take constant time step sizes.\n"
          << "  'Variable' - Integrator will allow changes to the time step "
          << "size.\n"
          << "  stepType = " << getStepType() << "\n");

  isInitialized_ = true;  // Only place where this is set to true!
}

template <class Scalar>
void TimeStepControl<Scalar>::printDtChanges(int istep, Scalar dt_old,
                                             Scalar dt_new,
                                             std::string reason) const
{
  if (!getPrintDtChanges()) return;

  Teuchos::RCP<Teuchos::FancyOStream> out = this->getOStream();
  out->setOutputToRootOnly(0);
  Teuchos::OSTab ostab(out, 0, "printDtChanges");

  std::stringstream message;
  message << std::scientific << std::setw(6) << std::setprecision(3) << istep
          << " *  (dt = " << std::setw(9) << std::setprecision(3) << dt_old
          << ", new = " << std::setw(9) << std::setprecision(3) << dt_new
          << ")  " << reason << std::endl;
  *out << message.str();
}

template <class Scalar>
void TimeStepControl<Scalar>::checkInitialized()
{
  if (!isInitialized_) {
    this->describe(*(this->getOStream()), Teuchos::VERB_MEDIUM);
    TEUCHOS_TEST_FOR_EXCEPTION(
        !isInitialized_, std::logic_error,
        "Error - " << this->description() << " is not initialized!");
  }
}

template <class Scalar>
void TimeStepControl<Scalar>::setNextTimeStep(
    const Teuchos::RCP<SolutionHistory<Scalar>>& solutionHistory,
    Status& integratorStatus)
{
  using Teuchos::RCP;

  checkInitialized();

  TEMPUS_FUNC_TIME_MONITOR("Tempus::TimeStepControl::setNextTimeStep()");
  {
    RCP<SolutionState<Scalar>> workingState =
        solutionHistory->getWorkingState();
    const Scalar lastTime = solutionHistory->getCurrentState()->getTime();
    const int iStep       = workingState->getIndex();
    Scalar dt             = workingState->getTimeStep();
    Scalar time           = workingState->getTime();

    RCP<StepperState<Scalar>> stepperState = workingState->getStepperState();

    // If last time step was adjusted for time event, reinstate previous dt.
    if (getStepType() == "Variable") {
      if (teAdjustedDt_ == true) {
        printDtChanges(iStep, dt, dtAfterTimeEvent_,
                       "Reset dt after time event.");
        dt                = dtAfterTimeEvent_;
        time              = lastTime + dt;
        teAdjustedDt_     = false;
        dtAfterTimeEvent_ = 0.0;
      }

      if (dt <= 0.0) {
        printDtChanges(iStep, dt, getInitTimeStep(), "Reset dt to initial dt.");
        dt   = getInitTimeStep();
        time = lastTime + dt;
      }

      if (dt < getMinTimeStep()) {
        printDtChanges(iStep, dt, getMinTimeStep(), "Reset dt to minimum dt.");
        dt   = getMinTimeStep();
        time = lastTime + dt;
      }
    }

    // Update dt for the step control strategy to be informed
    workingState->setTimeStep(dt);
    workingState->setTime(time);

    // Call the step control strategy (to update dt if needed)
    stepControlStrategy_->setNextTimeStep(*this, solutionHistory,
                                          integratorStatus);

    // Get the dt (It was probably changed by stepControlStrategy_.)
    dt   = workingState->getTimeStep();
    time = workingState->getTime();

    if (getStepType() == "Variable") {
      if (dt < getMinTimeStep()) {  // decreased below minimum dt
        printDtChanges(iStep, dt, getMinTimeStep(),
                       "dt is too small.  Resetting to minimum dt.");
        dt   = getMinTimeStep();
        time = lastTime + dt;
      }
      if (dt > getMaxTimeStep()) {  // increased above maximum dt
        printDtChanges(iStep, dt, getMaxTimeStep(),
                       "dt is too large.  Resetting to maximum dt.");
        dt   = getMaxTimeStep();
        time = lastTime + dt;
      }
    }

    // Check if this index is a TimeEvent and whether it is an output event.
    bool outputDueToIndex = false;
    std::vector<Teuchos::RCP<TimeEventBase<Scalar>>> constrainingTEs;
    if (timeEvent_->isIndex(iStep, constrainingTEs)) {
      for (auto& e : constrainingTEs) {
        if (e->getName() == "Output Index Interval" ||
            e->getName() == "Output Index List") {
          outputDueToIndex = true;
        }
      }
    }

    // Check if during this time step is there a TimeEvent.
    Scalar endTime = lastTime + dt;
    // For "Variable", need to check t+dt+t_min in case we need to split
    // the time step into two steps (e.g., time step lands within dt_min).
    if (getStepType() == "Variable") endTime = lastTime + dt + getMinTimeStep();

    bool teThisStep =
        timeEvent_->eventInRange(lastTime, endTime, constrainingTEs);

    bool outputDueToTime = false;
    Scalar tone          = endTime;
    bool landOnExactly   = false;
    if (teThisStep) {
      for (auto& e : constrainingTEs) {
        if (e->getName() == "Output Time Interval" ||
            e->getName() == "Output Time List") {
          outputDueToTime = true;
        }

        if (e->getLandOnExactly() == true) {
          landOnExactly = true;
          tone          = e->timeOfNextEvent(lastTime);
          break;
        }
      }
    }

    Scalar reltol = 1.0e-6;
    if (teThisStep && getStepType() == "Variable") {
      if (landOnExactly == true) {
        // Adjust time step to hit TimeEvent.
        if (time > tone) {
          // Next TimeEvent is not near next time.  It is more than
          // getMinTimeStep() away from it.
          printDtChanges(iStep, dt, tone - lastTime,
                         "Adjusting dt to hit the next TimeEvent.");
          teAdjustedDt_     = true;
          dtAfterTimeEvent_ = dt;
          dt                = tone - lastTime;
          time              = lastTime + dt;
        }
        else if (std::fabs(time - tone) < reltol * std::fabs(time)) {
          // Next TimeEvent IS VERY near next time.  It is less than
          // reltol away from it, e.g., adjust for numerical roundoff.
          printDtChanges(
              iStep, dt, tone - lastTime,
              "Adjusting dt for numerical roundoff to hit the next TimeEvent.");
          teAdjustedDt_     = true;
          dtAfterTimeEvent_ = dt;
          dt                = tone - lastTime;
          time              = lastTime + dt;
        }
        else if (std::fabs(time + getMinTimeStep() - tone) <
                 reltol * std::fabs(tone)) {
          // Next TimeEvent IS near next time.  It is less than
          // getMinTimeStep() away from it.  Take two time steps
          // to get to next TimeEvent.
          printDtChanges(
              iStep, dt, (tone - lastTime) / 2.0,
              "The next TimeEvent is within the minimum dt of the next time. "
              "Adjusting dt to take two steps.");
          dt   = (tone - lastTime) / 2.0;
          time = lastTime + dt;
          // This time step is no longer an output step due the time constraint.
          outputDueToTime = false;
        }
      }
    }

    // Adjust time step to hit final time or correct for small
    // numerical differences.
    if (getStepType() == "Variable") {
      if ((lastTime + dt > getFinalTime()) ||
          (std::fabs((lastTime + dt - getFinalTime())) <
           reltol * std::fabs(lastTime + dt))) {
        printDtChanges(iStep, dt, getFinalTime() - lastTime,
                       "Adjusting dt to hit final time.");
        dt   = getFinalTime() - lastTime;
        time = lastTime + dt;
      }
    }

    // Check for negative time step.
    TEUCHOS_TEST_FOR_EXCEPTION(
        dt <= Scalar(0.0), std::out_of_range,
        "Error - Time step is not positive.  dt = " << dt << "\n");

    // Time step always needs to keep time within range.
    TEUCHOS_TEST_FOR_EXCEPTION(
        (lastTime + dt < getInitTime()), std::out_of_range,
        "Error - Time step does not move time INTO time range.\n"
            << "    [timeMin, timeMax] = ["
            << getInitTime() << ", " << getFinalTime()
            << "]\n    T + dt = "
            << lastTime << " + " << dt << " = " << lastTime + dt << "\n");

    if (getStepType() == "Variable") {
      TEUCHOS_TEST_FOR_EXCEPTION(
          (lastTime + dt > getFinalTime()), std::out_of_range,
          "Error - Time step move time OUT OF time range.\n"
              << "    [timeMin, timeMax] = ["
              << getInitTime() << ", " << getFinalTime()
              << "]\n    T + dt = "
              << lastTime << " + " << dt << " = " << lastTime + dt << "\n");
    }

    workingState->setTimeStep(dt);
    workingState->setTime(time);
    workingState->setOutput(outputDueToIndex || outputDueToTime);
  }
  return;
}

template <class Scalar>
bool TimeStepControl<Scalar>::timeInRange(const Scalar time) const
{
  // Get absolute tolerance 1.0e-(i+14), i.e., 14 digits of accuracy.
  const int relTol        = 14;
  const int i             = (getInitTime() == 0)
                                ? 0
                                : 1 + (int)std::floor(std::log10(std::fabs(getInitTime())));
  const Scalar absTolInit = std::pow(10, i - relTol);
  const int j =
      (getFinalTime() == 0)
          ? 0
          : 1 + (int)std::floor(std::log10(std::fabs(getFinalTime())));
  const Scalar absTolFinal = std::pow(10, j - relTol);

  const bool test1 = getInitTime() - absTolInit <= time;
  const bool test2 = time < getFinalTime() - absTolFinal;

  return (test1 && test2);
}

template <class Scalar>
bool TimeStepControl<Scalar>::indexInRange(const int iStep) const
{
  bool iir = (getInitIndex() <= iStep && iStep < getFinalIndex());
  return iir;
}

template <class Scalar>
std::string TimeStepControl<Scalar>::getStepType() const
{
  TEUCHOS_TEST_FOR_EXCEPTION((stepControlStrategy_ == Teuchos::null),
                             std::logic_error,
                             "Error - getStepType() - Strategy is unset!\n");
  return stepControlStrategy_->getStepType();
}

template <class Scalar>
bool TimeStepControl<Scalar>::getOutputExactly() const
{
  auto event = timeEvent_->find("Output Time Interval");
  if (event != Teuchos::null) return event->getLandOnExactly();

  event = timeEvent_->find("Output Time List");
  if (event != Teuchos::null) return event->getLandOnExactly();

  return true;
}

template <class Scalar>
std::vector<int> TimeStepControl<Scalar>::getOutputIndices() const
{
  std::vector<int> indices;
  if (timeEvent_->find("Output Index List") == Teuchos::null) return indices;
  auto teli = Teuchos::rcp_dynamic_cast<TimeEventListIndex<Scalar>>(
      timeEvent_->find("Output Index List"));
  return teli->getIndexList();
}

template <class Scalar>
std::vector<Scalar> TimeStepControl<Scalar>::getOutputTimes() const
{
  std::vector<Scalar> times;
  if (timeEvent_->find("Output Time List") == Teuchos::null) return times;
  auto tel = Teuchos::rcp_dynamic_cast<TimeEventList<Scalar>>(
      timeEvent_->find("Output Time List"));
  return tel->getTimeList();
}

template <class Scalar>
int TimeStepControl<Scalar>::getOutputIndexInterval() const
{
  if (timeEvent_->find("Output Index Interval") == Teuchos::null)
    return 1000000;
  auto teri = Teuchos::rcp_dynamic_cast<TimeEventRangeIndex<Scalar>>(
      timeEvent_->find("Output Index Interval"));
  return teri->getIndexStride();
}

template <class Scalar>
Scalar TimeStepControl<Scalar>::getOutputTimeInterval() const
{
  if (timeEvent_->find("Output Time Interval") == Teuchos::null) return 1.0e+99;
  auto ter = Teuchos::rcp_dynamic_cast<TimeEventRange<Scalar>>(
      timeEvent_->find("Output Time Interval"));
  return ter->getTimeStride();
}

template <class Scalar>
void TimeStepControl<Scalar>::setNumTimeSteps(int numTimeSteps)
{
  TEUCHOS_TEST_FOR_EXCEPTION((getStepType() != "Constant"), std::out_of_range,
                             "Error - Can only use setNumTimeSteps() when "
                             "'Step Type' == 'Constant'.\n");

  numTimeSteps_ = numTimeSteps;
  if (numTimeSteps_ >= 0) {
    setFinalIndex(getInitIndex() + numTimeSteps_);
    Scalar initTimeStep;
    if (numTimeSteps_ == 0)
      initTimeStep = Scalar(0.0);
    else
      initTimeStep = (getFinalTime() - getInitTime()) / numTimeSteps_;
    setInitTimeStep(initTimeStep);
    setMinTimeStep(initTimeStep);
    setMaxTimeStep(initTimeStep);

    Teuchos::RCP<Teuchos::FancyOStream> out = this->getOStream();
    out->setOutputToRootOnly(0);
    Teuchos::OSTab ostab(out, 1, "setNumTimeSteps");
    *out << "Warning - setNumTimeSteps() Setting 'Number of Time Steps' = "
         << getNumTimeSteps() << "  Set the following parameters: \n"
         << "  'Final Time Index'     = " << getFinalIndex() << "\n"
         << "  'Initial Time Step'    = " << getInitTimeStep() << "\n"
         << "  'Step Type'            = " << getStepType() << std::endl;

    isInitialized_ = false;
  }
}

template <class Scalar>
void TimeStepControl<Scalar>::setOutputExactly(bool b)
{
  auto event = timeEvent_->find("Output Time Interval");
  if (event != Teuchos::null) {
    auto ter = Teuchos::rcp_dynamic_cast<TimeEventRange<Scalar>>(event);
    ter->setLandOnExactly(b);
  }
  event = timeEvent_->find("Output Time List");
  if (event != Teuchos::null) {
    auto tel = Teuchos::rcp_dynamic_cast<TimeEventList<Scalar>>(event);
    tel->setLandOnExactly(b);
  }
}

template <class Scalar>
void TimeStepControl<Scalar>::setOutputIndices(std::vector<int> outputIndices)
{
  timeEvent_->add(Teuchos::rcp(new Tempus::TimeEventListIndex<Scalar>(
      outputIndices, "Output Index List")));
  isInitialized_ = false;
}

template <class Scalar>
void TimeStepControl<Scalar>::setOutputTimes(std::vector<Scalar> outputTimes)
{
  timeEvent_->add(Teuchos::rcp(new Tempus::TimeEventList<Scalar>(
      outputTimes, "Output Time List", getOutputExactly())));
  isInitialized_ = false;
}

template <class Scalar>
void TimeStepControl<Scalar>::setOutputIndexInterval(int i)
{
  timeEvent_->add(Teuchos::rcp(new TimeEventRangeIndex<Scalar>(
      getInitIndex(), getFinalIndex(), i, "Output Index Interval")));
  isInitialized_ = false;
}

template <class Scalar>
void TimeStepControl<Scalar>::setOutputTimeInterval(Scalar t)
{
  timeEvent_->add(Teuchos::rcp(
      new TimeEventRange<Scalar>(getInitTime(), getFinalTime(), t,
                                 "Output Time Interval", getOutputExactly())));
  isInitialized_ = false;
}

template <class Scalar>
void TimeStepControl<Scalar>::setTimeEvents(
    Teuchos::RCP<TimeEventComposite<Scalar>> timeEvent)
{
  using Teuchos::rcp;

  if (timeEvent != Teuchos::null) {
    timeEvent_ = timeEvent;
  }
  else {
    auto tec = rcp(new TimeEventComposite<Scalar>());
    tec->setName("Time Step Control Events");
    tec->add(rcp(new TimeEventRangeIndex<Scalar>(
        getInitIndex(), getFinalIndex(), 1000000, "Output Index Interval")));
    tec->add(rcp(new TimeEventRange<Scalar>(
        getInitTime(), getFinalTime(), 1.0e+99, "Output Time Interval", true)));
    timeEvent_ = tec;
  }
  isInitialized_ = false;
}

template <class Scalar>
void TimeStepControl<Scalar>::setTimeStepControlStrategy(
    Teuchos::RCP<TimeStepControlStrategy<Scalar>> tscs)
{
  using Teuchos::rcp;

  if (tscs != Teuchos::null) {
    stepControlStrategy_ = tscs;
  }
  else {
    stepControlStrategy_ =
        rcp(new TimeStepControlStrategyConstant<Scalar>(getInitTimeStep()));
  }
  isInitialized_ = false;
}

template <class Scalar>
std::string TimeStepControl<Scalar>::description() const
{
  std::string name = "Tempus::TimeStepControl";
  return (name);
}

template <class Scalar>
void TimeStepControl<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 << "\n--- " << this->description() << " ---" << std::endl;

  if (Teuchos::as<int>(verbLevel) >= Teuchos::as<int>(Teuchos::VERB_MEDIUM)) {
    std::vector<int> idx = getOutputIndices();
    std::ostringstream listIdx;
    if (!idx.empty()) {
      for (std::size_t i = 0; i < idx.size() - 1; ++i)
        listIdx << idx[i] << ", ";
      listIdx << idx[idx.size() - 1];
    }

    std::vector<Scalar> times = getOutputTimes();
    std::ostringstream listTimes;
    if (!times.empty()) {
      for (std::size_t i = 0; i < times.size() - 1; ++i)
        listTimes << times[i] << ", ";
      listTimes << times[times.size() - 1];
    }

    *l_out << "  stepType           = " << getStepType() << std::endl
           << "  initTime           = " << getInitTime() << std::endl
           << "  finalTime          = " << getFinalTime() << std::endl
           << "  minTimeStep        = " << getMinTimeStep() << std::endl
           << "  initTimeStep       = " << getInitTimeStep() << std::endl
           << "  maxTimeStep        = " << getMaxTimeStep() << std::endl
           << "  initIndex          = " << getInitIndex() << std::endl
           << "  finalIndex         = " << getFinalIndex() << std::endl
           << "  maxAbsError        = " << getMaxAbsError() << std::endl
           << "  maxRelError        = " << getMaxRelError() << std::endl
           << "  maxFailures        = " << getMaxFailures() << std::endl
           << "  maxConsecFailures  = " << getMaxConsecFailures() << std::endl
           << "  numTimeSteps       = " << getNumTimeSteps() << std::endl
           << "  printDtChanges     = " << getPrintDtChanges() << std::endl
           << "  outputExactly      = " << getOutputExactly() << std::endl
           << "  outputIndices      = " << listIdx.str() << std::endl
           << "  outputTimes        = " << listTimes.str() << std::endl
           << "  outputIndexInterval= " << getOutputIndexInterval() << std::endl
           << "  outputTimeInterval = " << getOutputTimeInterval() << std::endl
           << "  outputAdjustedDt   = " << teAdjustedDt_ << std::endl
           << "  dtAfterOutput      = " << dtAfterTimeEvent_ << std::endl;
    stepControlStrategy_->describe(*l_out, verbLevel);
    timeEvent_->describe(*l_out, verbLevel);
  }
  *l_out << std::string(this->description().length() + 8, '-') << std::endl;
}

template <class Scalar>
Teuchos::RCP<const Teuchos::ParameterList>
TimeStepControl<Scalar>::getValidParameters() const
{
  Teuchos::RCP<Teuchos::ParameterList> pl =
      Teuchos::parameterList("Time Step Control");

  pl->set<double>("Initial Time", getInitTime(), "Initial time");
  pl->set<double>("Final Time", getFinalTime(), "Final time");
  pl->set<double>("Minimum Time Step", getMinTimeStep(),
                  "Minimum time step size");
  pl->set<double>("Initial Time Step", getInitTimeStep(),
                  "Initial time step size");
  pl->set<double>("Maximum Time Step", getMaxTimeStep(),
                  "Maximum time step size");
  pl->set<int>("Initial Time Index", getInitIndex(), "Initial time index");
  pl->set<int>("Final Time Index", getFinalIndex(), "Final time index");
  pl->set<int>(
      "Number of Time Steps", getNumTimeSteps(),
      "The number of constant time steps.  The actual step size gets computed\n"
      "on the fly given the size of the time domain.  Overides and resets\n"
      "  'Final Time Index'     = 'Initial Time Index' + 'Number of Time "
      "Steps'\n"
      "  'Initial Time Step'    = "
      "('Final Time' - 'Initial Time')/'Number of Time Steps'\n");
  pl->set<double>("Maximum Absolute Error", getMaxAbsError(),
                  "Maximum absolute error");
  pl->set<double>("Maximum Relative Error", getMaxRelError(),
                  "Maximum relative error");

  pl->set<bool>("Print Time Step Changes", getPrintDtChanges(),
                "Print timestep size when it changes");

  auto event = timeEvent_->find("Output Index Interval");
  if (event != Teuchos::null) {
    auto teri = Teuchos::rcp_dynamic_cast<TimeEventRangeIndex<Scalar>>(event);
    pl->set<int>("Output Index Interval", teri->getIndexStride(),
                 "Output Index Interval");
  }

  event = timeEvent_->find("Output Time Interval");
  if (event != Teuchos::null) {
    auto ter = Teuchos::rcp_dynamic_cast<TimeEventRange<Scalar>>(event);
    pl->set<double>("Output Time Interval", ter->getTimeStride(),
                    "Output time interval");
  }

  pl->set<bool>(
      "Output Exactly On Output Times", getOutputExactly(),
      "This determines if the timestep size will be adjusted to exactly land\n"
      "on the output times for 'Variable' timestepping (default=true).\n"
      "When set to 'false' or for 'Constant' time stepping, the timestep\n"
      "following the output time will be flagged for output.\n");

  {
    event = timeEvent_->find("Output Index List");
    std::ostringstream list;
    if (event != Teuchos::null) {
      auto teli            = Teuchos::rcp_dynamic_cast<TimeEventListIndex<Scalar>>(event);
      std::vector<int> idx = teli->getIndexList();
      if (!idx.empty()) {
        for (std::size_t i = 0; i < idx.size() - 1; ++i) list << idx[i] << ", ";
        list << idx[idx.size() - 1];
      }
    }
    pl->set<std::string>("Output Index List", list.str(),
                         "Comma deliminated list of output indices");
  }

  {
    event = timeEvent_->find("Output Time List");
    std::ostringstream list;
    if (event != Teuchos::null) {
      auto teli                 = Teuchos::rcp_dynamic_cast<TimeEventList<Scalar>>(event);
      std::vector<Scalar> times = teli->getTimeList();
      if (!times.empty()) {
        for (std::size_t i = 0; i < times.size() - 1; ++i)
          list << times[i] << ", ";
        list << times[times.size() - 1];
      }
    }
    pl->set<std::string>("Output Time List", list.str(),
                         "Comma deliminated list of output times");
  }

  {  // Do not duplicate the above "Output" events in "Time Step Control
     // Events".
    auto tecTmp = Teuchos::rcp(new TimeEventComposite<Scalar>());
    tecTmp->setTimeEvents(timeEvent_->getTimeEvents());
    tecTmp->remove("Output Index Interval");
    tecTmp->remove("Output Time Interval");
    tecTmp->remove("Output Index List");
    tecTmp->remove("Output Time List");
    if (tecTmp->getSize() > 0)
      pl->set("Time Step Control Events", *tecTmp->getValidParameters());
  }

  pl->set<int>("Maximum Number of Stepper Failures", getMaxFailures(),
               "Maximum number of Stepper failures");
  pl->set<int>("Maximum Number of Consecutive Stepper Failures",
               getMaxConsecFailures(),
               "Maximum number of consecutive Stepper failures");

  pl->set("Time Step Control Strategy",
          *stepControlStrategy_->getValidParameters());

  return pl;
}

// Nonmember constructor - ParameterList
// ------------------------------------------------------------------------
template <class Scalar>
Teuchos::RCP<TimeStepControl<Scalar>> createTimeStepControl(
    Teuchos::RCP<Teuchos::ParameterList> const& pList, bool runInitialize)
{
  using Teuchos::ParameterList;
  using Teuchos::RCP;
  using Teuchos::rcp;

  auto tsc = Teuchos::rcp(new TimeStepControl<Scalar>());
  if (pList == Teuchos::null || pList->numParams() == 0) return tsc;

  auto tscValidPL =
      Teuchos::rcp_const_cast<ParameterList>(tsc->getValidParameters());
  // Handle optional "Time Step Control Events" sublist.
  if (pList->isSublist("Time Step Control Events")) {
    RCP<ParameterList> tsctePL =
        Teuchos::sublist(pList, "Time Step Control Events", true);
    tscValidPL->set("Time Step Control Events", *tsctePL);
  }

  pList->validateParametersAndSetDefaults(*tscValidPL, 0);

  tsc->setInitTime(pList->get<double>("Initial Time"));
  tsc->setFinalTime(pList->get<double>("Final Time"));
  tsc->setMinTimeStep(pList->get<double>("Minimum Time Step"));
  tsc->setInitTimeStep(pList->get<double>("Initial Time Step"));
  tsc->setMaxTimeStep(pList->get<double>("Maximum Time Step"));
  tsc->setInitIndex(pList->get<int>("Initial Time Index"));
  tsc->setFinalIndex(pList->get<int>("Final Time Index"));
  tsc->setMaxAbsError(pList->get<double>("Maximum Absolute Error"));
  tsc->setMaxRelError(pList->get<double>("Maximum Relative Error"));
  tsc->setMaxFailures(pList->get<int>("Maximum Number of Stepper Failures"));
  tsc->setMaxConsecFailures(
      pList->get<int>("Maximum Number of Consecutive Stepper Failures"));
  tsc->setPrintDtChanges(pList->get<bool>("Print Time Step Changes"));
  tsc->setNumTimeSteps(pList->get<int>("Number of Time Steps"));

  auto tec = rcp(new TimeEventComposite<Scalar>());
  tec->setName("Time Step Control Events");

  {  // Parse output indices, "Output Index List".
    std::vector<int> outputIndices;
    outputIndices.clear();
    std::string str = pList->get<std::string>("Output Index List");
    std::string delimiters(",");
    std::string::size_type lastPos = str.find_first_not_of(delimiters, 0);
    std::string::size_type pos     = str.find_first_of(delimiters, lastPos);
    while ((pos != std::string::npos) || (lastPos != std::string::npos)) {
      std::string token = str.substr(lastPos, pos - lastPos);
      outputIndices.push_back(int(std::stoi(token)));
      if (pos == std::string::npos) break;

      lastPos = str.find_first_not_of(delimiters, pos);
      pos     = str.find_first_of(delimiters, lastPos);
    }

    if (!outputIndices.empty()) {
      // order output indices
      std::sort(outputIndices.begin(), outputIndices.end());
      outputIndices.erase(
          std::unique(outputIndices.begin(), outputIndices.end()),
          outputIndices.end());

      tec->add(rcp(new Tempus::TimeEventListIndex<Scalar>(
          outputIndices, "Output Index List")));
    }
  }

  // Parse output index internal
  tec->add(rcp(new TimeEventRangeIndex<Scalar>(
      tsc->getInitIndex(), tsc->getFinalIndex(),
      pList->get<int>("Output Index Interval"), "Output Index Interval")));

  auto outputExactly = pList->get<bool>("Output Exactly On Output Times", true);

  {  // Parse output times, "Output Time List".
    std::vector<Scalar> outputTimes;
    outputTimes.clear();
    std::string str = pList->get<std::string>("Output Time List");
    std::string delimiters(",");
    // Skip delimiters at the beginning
    std::string::size_type lastPos = str.find_first_not_of(delimiters, 0);
    // Find the first delimiter
    std::string::size_type pos = str.find_first_of(delimiters, lastPos);
    while ((pos != std::string::npos) || (lastPos != std::string::npos)) {
      // Found a token, add it to the vector
      std::string token = str.substr(lastPos, pos - lastPos);
      outputTimes.push_back(Scalar(std::stod(token)));
      if (pos == std::string::npos) break;

      lastPos = str.find_first_not_of(delimiters, pos);  // Skip delimiters
      pos     = str.find_first_of(delimiters, lastPos);  // Find next delimiter
    }

    if (!outputTimes.empty()) {
      // order output times
      std::sort(outputTimes.begin(), outputTimes.end());
      outputTimes.erase(std::unique(outputTimes.begin(), outputTimes.end()),
                        outputTimes.end());

      tec->add(rcp(new Tempus::TimeEventList<Scalar>(
          outputTimes, "Output Time List", outputExactly)));
    }
  }

  // Parse output time interval
  tec->add(
      rcp(new TimeEventRange<Scalar>(tsc->getInitTime(), tsc->getFinalTime(),
                                     pList->get<double>("Output Time Interval"),
                                     "Output Time Interval", outputExactly)));

  if (pList->isSublist("Time Step Control Events")) {
    RCP<ParameterList> tsctePL =
        Teuchos::sublist(pList, "Time Step Control Events", true);

    auto timeEventType = tsctePL->get<std::string>("Type", "Unknown");
    if (timeEventType == "Range") {
      tec->add(createTimeEventRange<Scalar>(tsctePL));
    }
    else if (timeEventType == "Range Index") {
      tec->add(createTimeEventRangeIndex<Scalar>(tsctePL));
    }
    else if (timeEventType == "List") {
      tec->add(createTimeEventList<Scalar>(tsctePL));
    }
    else if (timeEventType == "List Index") {
      tec->add(createTimeEventListIndex<Scalar>(tsctePL));
    }
    else if (timeEventType == "Composite") {
      auto tecTmp     = createTimeEventComposite<Scalar>(tsctePL);
      auto timeEvents = tecTmp->getTimeEvents();
      for (auto& e : timeEvents) tec->add(e);
    }
    else {
      RCP<Teuchos::FancyOStream> out =
          Teuchos::fancyOStream(Teuchos::rcpFromRef(std::cout));
      out->setOutputToRootOnly(0);
      Teuchos::OSTab ostab(out, 1, "createTimeStepControl()");
      *out << "Warning -- Unknown Time Event Type!\n"
           << "'Type' = '" << timeEventType << "'\n"
           << "Should call add() with this "
           << "(app-specific?) Time Event.\n"
           << std::endl;
    }
  }

  tsc->setTimeEvents(tec);

  if (!pList->isParameter("Time Step Control Strategy")) {
    tsc->setTimeStepControlStrategy();  // i.e., set default Constant timestep
                                        // strategy.
  }
  else {
    RCP<ParameterList> tscsPL =
        Teuchos::sublist(pList, "Time Step Control Strategy", true);

    auto strategyType = tscsPL->get<std::string>("Strategy Type");
    if (strategyType == "Constant") {
      tsc->setTimeStepControlStrategy(
          createTimeStepControlStrategyConstant<Scalar>(tscsPL));
    }
    else if (strategyType == "Basic VS") {
      tsc->setTimeStepControlStrategy(
          createTimeStepControlStrategyBasicVS<Scalar>(tscsPL));
    }
    else if (strategyType == "Integral Controller") {
      tsc->setTimeStepControlStrategy(
          createTimeStepControlStrategyIntegralController<Scalar>(tscsPL));
    }
    else if (strategyType == "Composite") {
      tsc->setTimeStepControlStrategy(
          createTimeStepControlStrategyComposite<Scalar>(tscsPL));
    }
    else {
      RCP<Teuchos::FancyOStream> out =
          Teuchos::fancyOStream(Teuchos::rcpFromRef(std::cout));
      out->setOutputToRootOnly(0);
      Teuchos::OSTab ostab(out, 1, "createTimeStepControl()");
      *out << "Warning -- Did not find a Tempus strategy to create!\n"
           << "'Strategy Type' = '" << strategyType << "'\n"
           << "Should call setTimeStepControlStrategy() with this\n"
           << "(app-specific?) strategy, and initialize().\n"
           << std::endl;
    }
  }

  if (runInitialize) tsc->initialize();
  return tsc;
}

}  // namespace Tempus
#endif  // Tempus_TimeStepControl_impl_hpp