@Override
  public void optimize(Point initial, OptimizationController control) throws OptimizationException {

    if (initial.dim() != 1) {
      throw new IllegalArgumentException(
          "Only single-dimensional optimization supported, dim=" + initial.dim());
    }

    log.info("Starting golden section search for optimization");

    Point guessAC = null;
    Point guessBD = null;

    try {
      boolean guessedAC;

      Point previous = p(0);
      double previousValue = Double.NaN;
      current = previous;
      double currentValue = Double.NaN;

      /*
       * Initialize the points + computation.
       */
      Point a = p(0);
      Point d = p(1.0);
      Point b = section1(a, d);
      Point c = section2(a, d);

      functionExecutor.compute(a);
      functionExecutor.compute(d);
      functionExecutor.compute(b);
      functionExecutor.compute(c);

      // Wait for points a and d, which normally are already precomputed
      functionExecutor.waitFor(a);
      functionExecutor.waitFor(d);

      boolean continueOptimization = true;
      while (continueOptimization) {

        /*
         * Get values at A & D for guessing.
         * These are pre-calculated except during the first step.
         */
        double fa, fd;
        fa = functionExecutor.getValue(a);
        fd = functionExecutor.getValue(d);

        /*
         * Start calculating possible two next points.  The order of evaluation
         * is selected based on the function values at A and D.
         */
        guessAC = section1(a, c);
        guessBD = section2(b, d);
        if (Double.isNaN(fd) || fa < fd) {
          guessedAC = true;
          functionExecutor.compute(guessAC);
          functionExecutor.compute(guessBD);
        } else {
          guessedAC = false;
          functionExecutor.compute(guessBD);
          functionExecutor.compute(guessAC);
        }

        /*
         * Get values at B and C.
         */
        double fb, fc;
        functionExecutor.waitFor(b);
        functionExecutor.waitFor(c);
        fb = functionExecutor.getValue(b);
        fc = functionExecutor.getValue(c);

        double min = MathUtil.min(fa, fb, fc, fd);
        if (Double.isNaN(min)) {
          throw new OptimizationException("Unable to compute initial function values");
        }

        /*
         * Update previous and current values for step control.
         */
        previousValue = currentValue;
        currentValue = min;
        previous = current;
        if (min == fa) {
          current = a;
        } else if (min == fb) {
          current = b;
        } else if (min == fc) {
          current = c;
        } else {
          current = d;
        }

        /*
         * Select next positions.  These are already being calculated in the background
         * as guessAC and guessBD.
         */
        if (min == fa || min == fb) {
          d = c;
          c = b;
          b = guessAC;
          functionExecutor.abort(guessBD);
          guessBD = null;
          log.debug("Selecting A-C region, a=" + a.get(0) + " c=" + c.get(0));
          if (guessedAC) {
            guessSuccess++;
          } else {
            guessFailure++;
          }
        } else {
          a = b;
          b = c;
          c = guessBD;
          functionExecutor.abort(guessAC);
          guessAC = null;
          log.debug("Selecting B-D region, b=" + b.get(0) + " d=" + d.get(0));
          if (!guessedAC) {
            guessSuccess++;
          } else {
            guessFailure++;
          }
        }

        /*
         * Check optimization control.
         */
        continueOptimization =
            control.stepTaken(previous, previousValue, current, currentValue, c.get(0) - a.get(0));

        if (Thread.interrupted()) {
          throw new InterruptedException();
        }
      }

    } catch (InterruptedException e) {
      log.info("Optimization was interrupted with InterruptedException");
    }

    if (guessAC != null) {
      functionExecutor.abort(guessAC);
    }
    if (guessBD != null) {
      functionExecutor.abort(guessBD);
    }

    log.info(
        "Finishing optimization at point " + getOptimumPoint() + " value " + getOptimumValue());
    log.info("Optimization statistics: " + getStatistics());
  }
  @Override
  public FlightData simulate(SimulationConditions simulationConditions) throws SimulationException {
    Set<MotorId> motorBurntOut = new HashSet<MotorId>();

    // Set up flight data
    FlightData flightData = new FlightData();

    // Set up rocket configuration
    Configuration configuration = setupConfiguration(simulationConditions);
    MotorInstanceConfiguration motorConfiguration = setupMotorConfiguration(configuration);
    if (motorConfiguration.getMotorIDs().isEmpty()) {
      throw new MotorIgnitionException("No motors defined in the simulation.");
    }

    // Initialize the simulation
    currentStepper = flightStepper;
    status = initialStatus(configuration, motorConfiguration, simulationConditions, flightData);
    status = currentStepper.initialize(status);

    SimulationListenerHelper.fireStartSimulation(status);
    // Get originating position (in case listener has modified launch position)
    Coordinate origin = status.getRocketPosition();
    Coordinate originVelocity = status.getRocketVelocity();

    try {
      double maxAlt = Double.NEGATIVE_INFINITY;

      // Start the simulation
      while (handleEvents()) {

        // Take the step
        double oldAlt = status.getRocketPosition().z;

        if (SimulationListenerHelper.firePreStep(status)) {
          // Step at most to the next event
          double maxStepTime = Double.MAX_VALUE;
          FlightEvent nextEvent = status.getEventQueue().peek();
          if (nextEvent != null) {
            maxStepTime = MathUtil.max(nextEvent.getTime() - status.getSimulationTime(), 0.001);
          }
          log.verbose(
              "BasicEventSimulationEngine: Taking simulation step at t="
                  + status.getSimulationTime());
          currentStepper.step(status, maxStepTime);
        }
        SimulationListenerHelper.firePostStep(status);

        // Calculate values for custom expressions
        FlightDataBranch data = status.getFlightData();
        ArrayList<CustomExpression> allExpressions =
            status.getSimulationConditions().getSimulation().getCustomExpressions();
        for (CustomExpression expression : allExpressions) {
          data.setValue(expression.getType(), expression.evaluate(status));
        }

        // Check for NaN values in the simulation status
        checkNaN();

        // Add altitude event
        addEvent(
            new FlightEvent(
                FlightEvent.Type.ALTITUDE,
                status.getSimulationTime(),
                status.getConfiguration().getRocket(),
                new Pair<Double, Double>(oldAlt, status.getRocketPosition().z)));

        if (status.getRocketPosition().z > maxAlt) {
          maxAlt = status.getRocketPosition().z;
        }

        // Position relative to start location
        Coordinate relativePosition = status.getRocketPosition().sub(origin);

        // Add appropriate events
        if (!status.isLiftoff()) {

          // Avoid sinking into ground before liftoff
          if (relativePosition.z < 0) {
            status.setRocketPosition(origin);
            status.setRocketVelocity(originVelocity);
          }
          // Detect lift-off
          if (relativePosition.z > 0.02) {
            addEvent(new FlightEvent(FlightEvent.Type.LIFTOFF, status.getSimulationTime()));
          }

        } else {

          // Check ground hit after liftoff
          if (status.getRocketPosition().z < 0) {
            status.setRocketPosition(status.getRocketPosition().setZ(0));
            addEvent(new FlightEvent(FlightEvent.Type.GROUND_HIT, status.getSimulationTime()));
            addEvent(new FlightEvent(FlightEvent.Type.SIMULATION_END, status.getSimulationTime()));
          }
        }

        // Check for launch guide clearance
        if (!status.isLaunchRodCleared()
            && relativePosition.length() > status.getSimulationConditions().getLaunchRodLength()) {
          addEvent(new FlightEvent(FlightEvent.Type.LAUNCHROD, status.getSimulationTime(), null));
        }

        // Check for apogee
        if (!status.isApogeeReached() && status.getRocketPosition().z < maxAlt - 0.01) {
          addEvent(
              new FlightEvent(
                  FlightEvent.Type.APOGEE,
                  status.getSimulationTime(),
                  status.getConfiguration().getRocket()));
        }

        // Check for burnt out motors
        for (MotorId motorId : status.getMotorConfiguration().getMotorIDs()) {
          MotorInstance motor = status.getMotorConfiguration().getMotorInstance(motorId);
          if (!motor.isActive() && motorBurntOut.add(motorId)) {
            addEvent(
                new FlightEvent(
                    FlightEvent.Type.BURNOUT,
                    status.getSimulationTime(),
                    (RocketComponent) status.getMotorConfiguration().getMotorMount(motorId),
                    motorId));
          }
        }
      }

    } catch (SimulationException e) {
      SimulationListenerHelper.fireEndSimulation(status, e);
      throw e;
    }

    SimulationListenerHelper.fireEndSimulation(status, null);

    flightData.addBranch(status.getFlightData());

    if (!flightData.getWarningSet().isEmpty()) {
      log.info("Warnings at the end of simulation:  " + flightData.getWarningSet());
    }

    // TODO: HIGH: Simulate branches
    return flightData;
  }