AbstractIntegratedPropagator.java

  1. /* Copyright 2002-2024 CS GROUP
  2.  * Licensed to CS GROUP (CS) under one or more
  3.  * contributor license agreements.  See the NOTICE file distributed with
  4.  * this work for additional information regarding copyright ownership.
  5.  * CS licenses this file to You under the Apache License, Version 2.0
  6.  * (the "License"); you may not use this file except in compliance with
  7.  * the License.  You may obtain a copy of the License at
  8.  *
  9.  *   http://www.apache.org/licenses/LICENSE-2.0
  10.  *
  11.  * Unless required by applicable law or agreed to in writing, software
  12.  * distributed under the License is distributed on an "AS IS" BASIS,
  13.  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  14.  * See the License for the specific language governing permissions and
  15.  * limitations under the License.
  16.  */
  17. package org.orekit.propagation.integration;

  19. import java.util.ArrayList;
  20. import java.util.Arrays;
  21. import java.util.Collection;
  22. import java.util.Collections;
  23. import java.util.HashMap;
  24. import java.util.LinkedList;
  25. import java.util.List;
  26. import java.util.Map;
  27. import java.util.Queue;

  29. import org.hipparchus.analysis.UnivariateFunction;
  30. import org.hipparchus.analysis.solvers.BracketedUnivariateSolver;
  31. import org.hipparchus.analysis.solvers.BracketingNthOrderBrentSolver;
  32. import org.hipparchus.exception.MathRuntimeException;
  33. import org.hipparchus.ode.DenseOutputModel;
  34. import org.hipparchus.ode.ExpandableODE;
  35. import org.hipparchus.ode.ODEIntegrator;
  36. import org.hipparchus.ode.ODEState;
  37. import org.hipparchus.ode.ODEStateAndDerivative;
  38. import org.hipparchus.ode.OrdinaryDifferentialEquation;
  39. import org.hipparchus.ode.SecondaryODE;
  40. import org.hipparchus.ode.events.Action;
  41. import org.hipparchus.ode.events.AdaptableInterval;
  42. import org.hipparchus.ode.events.ODEEventDetector;
  43. import org.hipparchus.ode.events.ODEEventHandler;
  44. import org.hipparchus.ode.sampling.AbstractODEStateInterpolator;
  45. import org.hipparchus.ode.sampling.ODEStateInterpolator;
  46. import org.hipparchus.ode.sampling.ODEStepHandler;
  47. import org.hipparchus.util.Precision;
  48. import org.orekit.attitudes.AttitudeProvider;
  49. import org.orekit.errors.OrekitException;
  50. import org.orekit.errors.OrekitInternalError;
  51. import org.orekit.errors.OrekitMessages;
  52. import org.orekit.frames.Frame;
  53. import org.orekit.orbits.OrbitType;
  54. import org.orekit.orbits.PositionAngleType;
  55. import org.orekit.propagation.AbstractPropagator;
  56. import org.orekit.propagation.BoundedPropagator;
  57. import org.orekit.propagation.EphemerisGenerator;
  58. import org.orekit.propagation.PropagationType;
  59. import org.orekit.propagation.SpacecraftState;
  60. import org.orekit.propagation.events.EventDetector;
  61. import org.orekit.propagation.events.handlers.EventHandler;
  62. import org.orekit.propagation.sampling.OrekitStepHandler;
  63. import org.orekit.propagation.sampling.OrekitStepInterpolator;
  64. import org.orekit.time.AbsoluteDate;
  65. import org.orekit.utils.DoubleArrayDictionary;


  68. /** Common handling of {@link org.orekit.propagation.Propagator Propagator}
  69.  *  methods for both numerical and semi-analytical propagators.
  70.  *  @author Luc Maisonobe
  71.  */
  72. public abstract class AbstractIntegratedPropagator extends AbstractPropagator {

  74.     /** Internal name used for complete secondary state dimension.
  75.      * @since 11.1
  76.      */
  77.     private static final String SECONDARY_DIMENSION = "Orekit-secondary-dimension";

  79.     /** Event detectors not related to force models. */
  80.     private final List<EventDetector> detectors;

  82.     /** Step handlers dedicated to ephemeris generation. */
  83.     private final List<StoringStepHandler> ephemerisGenerators;

  85.     /** Integrator selected by the user for the orbital extrapolation process. */
  86.     private final ODEIntegrator integrator;

  88.     /** Offsets of secondary states managed by {@link AdditionalDerivativesProvider}.
  89.      * @since 11.1
  90.      */
  91.     private final Map<String, Integer> secondaryOffsets;

  93.     /** Additional derivatives providers.
  94.      * @since 11.1
  95.      */
  96.     private final List<AdditionalDerivativesProvider> additionalDerivativesProviders;

  98.     /** Map of secondary equation offset in main
  99.     /** Counter for differential equations calls. */
  100.     private int calls;

  102.     /** Mapper between raw double components and space flight dynamics objects. */
  103.     private StateMapper stateMapper;

  105.     /**
  106.      * Attitude provider when evaluating derivatives. Can be a frozen one for performance.
  107.      * @since 12.1
  108.      */
  109.     private AttitudeProvider attitudeProviderForDerivatives;

  111.     /** Flag for resetting the state at end of propagation. */
  112.     private boolean resetAtEnd;

  114.     /** Type of orbit to output (mean or osculating) <br/>
  115.      * <p>
  116.      * This is used only in the case of semi-analytical propagators where there is a clear separation between
  117.      * mean and short periodic elements. It is ignored by the Numerical propagator.
  118.      * </p>
  119.      */
  120.     private final PropagationType propagationType;

  122.     /** Build a new instance.
  123.      * @param integrator numerical integrator to use for propagation.
  124.      * @param propagationType type of orbit to output (mean or osculating).
  125.      */
  126.     protected AbstractIntegratedPropagator(final ODEIntegrator integrator, final PropagationType propagationType) {
  127.         detectors                      = new ArrayList<>();
  128.         ephemerisGenerators            = new ArrayList<>();
  129.         additionalDerivativesProviders = new ArrayList<>();
  130.         this.secondaryOffsets          = new HashMap<>();
  131.         this.integrator                = integrator;
  132.         this.propagationType           = propagationType;
  133.         this.resetAtEnd                = true;
  134.     }

  136.     /** Allow/disallow resetting the initial state at end of propagation.
  137.      * <p>
  138.      * By default, at the end of the propagation, the propagator resets the initial state
  139.      * to the final state, thus allowing a new propagation to be started from there without
  140.      * recomputing the part already performed. Calling this method with {@code resetAtEnd} set
  141.      * to false changes prevents such reset.
  142.      * </p>
  143.      * @param resetAtEnd if true, at end of each propagation, the {@link
  144.      * #getInitialState() initial state} will be reset to the final state of
  145.      * the propagation, otherwise the initial state will be preserved
  146.      * @since 9.0
  147.      */
  148.     public void setResetAtEnd(final boolean resetAtEnd) {
  149.         this.resetAtEnd = resetAtEnd;
  150.     }

  152.     /** Getter for the resetting flag regarding initial state.
  153.      * @return resetting flag
  154.      * @since 12.0
  155.      */
  156.     public boolean getResetAtEnd() {
  157.         return this.resetAtEnd;
  158.     }

  160.     /**
  161.      * Method called when initializing the attitude provider used when evaluating derivatives.
  162.      * @return attitude provider for derivatives
  163.      */
  164.     protected AttitudeProvider initializeAttitudeProviderForDerivatives() {
  165.         return getAttitudeProvider();
  166.     }

  168.     /** Initialize the mapper. */
  169.     protected void initMapper() {
  170.         stateMapper = createMapper(null, Double.NaN, null, null, null, null);
  171.     }

  173.     /** Get the integrator's name.
  174.      * @return name of underlying integrator
  175.      * @since 12.0
  176.      */
  177.     public String getIntegratorName() {
  178.         return integrator.getName();
  179.     }

  181.     /**  {@inheritDoc} */
  182.     @Override
  183.     public void setAttitudeProvider(final AttitudeProvider attitudeProvider) {
  184.         super.setAttitudeProvider(attitudeProvider);
  185.         stateMapper = createMapper(stateMapper.getReferenceDate(), stateMapper.getMu(),
  186.                                    stateMapper.getOrbitType(), stateMapper.getPositionAngleType(),
  187.                                    attitudeProvider, stateMapper.getFrame());
  188.     }

  190.     /** Set propagation orbit type.
  191.      * @param orbitType orbit type to use for propagation, null for
  192.      * propagating using {@link org.orekit.utils.AbsolutePVCoordinates AbsolutePVCoordinates}
  193.      * rather than {@link org.orekit.orbits Orbit}
  194.      */
  195.     protected void setOrbitType(final OrbitType orbitType) {
  196.         stateMapper = createMapper(stateMapper.getReferenceDate(), stateMapper.getMu(),
  197.                                    orbitType, stateMapper.getPositionAngleType(),
  198.                                    stateMapper.getAttitudeProvider(), stateMapper.getFrame());
  199.     }

  201.     /** Get propagation parameter type.
  202.      * @return orbit type used for propagation, null for
  203.      * propagating using {@link org.orekit.utils.AbsolutePVCoordinates AbsolutePVCoordinates}
  204.      * rather than {@link org.orekit.orbits Orbit}
  205.      */
  206.     protected OrbitType getOrbitType() {
  207.         return stateMapper.getOrbitType();
  208.     }

  210.     /** Get the propagation type.
  211.      * @return propagation type.
  212.      * @since 11.1
  213.      */
  214.     public PropagationType getPropagationType() {
  215.         return propagationType;
  216.     }

  218.     /** Set position angle type.
  219.      * <p>
  220.      * The position parameter type is meaningful only if {@link
  221.      * #getOrbitType() propagation orbit type}
  222.      * support it. As an example, it is not meaningful for propagation
  223.      * in {@link OrbitType#CARTESIAN Cartesian} parameters.
  224.      * </p>
  225.      * @param positionAngleType angle type to use for propagation
  226.      */
  227.     protected void setPositionAngleType(final PositionAngleType positionAngleType) {
  228.         stateMapper = createMapper(stateMapper.getReferenceDate(), stateMapper.getMu(),
  229.                                    stateMapper.getOrbitType(), positionAngleType,
  230.                                    stateMapper.getAttitudeProvider(), stateMapper.getFrame());
  231.     }

  233.     /** Get propagation parameter type.
  234.      * @return angle type to use for propagation
  235.      */
  236.     protected PositionAngleType getPositionAngleType() {
  237.         return stateMapper.getPositionAngleType();
  238.     }

  240.     /** Set the central attraction coefficient μ.
  241.      * @param mu central attraction coefficient (m³/s²)
  242.      */
  243.     public void setMu(final double mu) {
  244.         stateMapper = createMapper(stateMapper.getReferenceDate(), mu,
  245.                                    stateMapper.getOrbitType(), stateMapper.getPositionAngleType(),
  246.                                    stateMapper.getAttitudeProvider(), stateMapper.getFrame());
  247.     }

  249.     /** Get the central attraction coefficient μ.
  250.      * @return mu central attraction coefficient (m³/s²)
  251.      * @see #setMu(double)
  252.      */
  253.     public double getMu() {
  254.         return stateMapper.getMu();
  255.     }

  257.     /** Get the number of calls to the differential equations computation method.
  258.      * <p>The number of calls is reset each time the {@link #propagate(AbsoluteDate)}
  259.      * method is called.</p>
  260.      * @return number of calls to the differential equations computation method
  261.      */
  262.     public int getCalls() {
  263.         return calls;
  264.     }

  266.     /** {@inheritDoc} */
  267.     @Override
  268.     public boolean isAdditionalStateManaged(final String name) {

  270.         // first look at already integrated states
  271.         if (super.isAdditionalStateManaged(name)) {
  272.             return true;
  273.         }

  275.         // then look at states we integrate ourselves
  276.         for (final AdditionalDerivativesProvider provider : additionalDerivativesProviders) {
  277.             if (provider.getName().equals(name)) {
  278.                 return true;
  279.             }
  280.         }

  282.         return false;
  283.     }

  285.     /** {@inheritDoc} */
  286.     @Override
  287.     public String[] getManagedAdditionalStates() {
  288.         final String[] alreadyIntegrated = super.getManagedAdditionalStates();
  289.         final String[] managed = new String[alreadyIntegrated.length + additionalDerivativesProviders.size()];
  290.         System.arraycopy(alreadyIntegrated, 0, managed, 0, alreadyIntegrated.length);
  291.         for (int i = 0; i < additionalDerivativesProviders.size(); ++i) {
  292.             managed[i + alreadyIntegrated.length] = additionalDerivativesProviders.get(i).getName();
  293.         }
  294.         return managed;
  295.     }

  297.     /** Add a provider for user-specified state derivatives to be integrated along with the orbit propagation.
  298.      * @param provider provider for additional derivatives
  299.      * @see #addAdditionalStateProvider(org.orekit.propagation.AdditionalStateProvider)
  300.      * @since 11.1
  301.      */
  302.     public void addAdditionalDerivativesProvider(final AdditionalDerivativesProvider provider) {

  304.         // check if the name is already used
  305.         if (isAdditionalStateManaged(provider.getName())) {
  306.             // these derivatives are already registered, complain
  307.             throw new OrekitException(OrekitMessages.ADDITIONAL_STATE_NAME_ALREADY_IN_USE,
  308.                                       provider.getName());
  309.         }

  311.         // this is really a new set of derivatives, add it
  312.         additionalDerivativesProviders.add(provider);

  314.         secondaryOffsets.clear();

  316.     }

  318.     /** Get an unmodifiable list of providers for additional derivatives.
  319.      * @return providers for the additional derivatives
  320.      * @since 11.1
  321.      */
  322.     public List<AdditionalDerivativesProvider> getAdditionalDerivativesProviders() {
  323.         return Collections.unmodifiableList(additionalDerivativesProviders);
  324.     }

  326.     /** {@inheritDoc} */
  327.     public void addEventDetector(final EventDetector detector) {
  328.         detectors.add(detector);
  329.     }

  331.     /** {@inheritDoc} */
  332.     public Collection<EventDetector> getEventsDetectors() {
  333.         return Collections.unmodifiableCollection(detectors);
  334.     }

  336.     /** {@inheritDoc} */
  337.     public void clearEventsDetectors() {
  338.         detectors.clear();
  339.     }

  341.     /** Set up all user defined event detectors.
  342.      */
  343.     protected void setUpUserEventDetectors() {
  344.         for (final EventDetector detector : detectors) {
  345.             setUpEventDetector(integrator, detector);
  346.         }
  347.     }

  349.     /** Wrap an Orekit event detector and register it to the integrator.
  350.      * @param integ integrator into which event detector should be registered
  351.      * @param detector event detector to wrap
  352.      */
  353.     protected void setUpEventDetector(final ODEIntegrator integ, final EventDetector detector) {
  354.         integ.addEventDetector(new AdaptedEventDetector(detector));
  355.     }

  357.     /** {@inheritDoc} */
  358.     @Override
  359.     public EphemerisGenerator getEphemerisGenerator() {
  360.         final StoringStepHandler storingHandler = new StoringStepHandler();
  361.         ephemerisGenerators.add(storingHandler);
  362.         return storingHandler;
  363.     }

  365.     /** Create a mapper between raw double components and spacecraft state.
  366.     /** Simple constructor.
  367.      * <p>
  368.      * The position parameter type is meaningful only if {@link
  369.      * #getOrbitType() propagation orbit type}
  370.      * support it. As an example, it is not meaningful for propagation
  371.      * in {@link OrbitType#CARTESIAN Cartesian} parameters.
  372.      * </p>
  373.      * @param referenceDate reference date
  374.      * @param mu central attraction coefficient (m³/s²)
  375.      * @param orbitType orbit type to use for mapping
  376.      * @param positionAngleType angle type to use for propagation
  377.      * @param attitudeProvider attitude provider
  378.      * @param frame inertial frame
  379.      * @return new mapper
  380.      */
  381.     protected abstract StateMapper createMapper(AbsoluteDate referenceDate, double mu,
  382.                                                 OrbitType orbitType, PositionAngleType positionAngleType,
  383.                                                 AttitudeProvider attitudeProvider, Frame frame);

  385.     /** Get the differential equations to integrate (for main state only).
  386.      * @param integ numerical integrator to use for propagation.
  387.      * @return differential equations for main state
  388.      */
  389.     protected abstract MainStateEquations getMainStateEquations(ODEIntegrator integ);

  391.     /** {@inheritDoc} */
  392.     @Override
  393.     public SpacecraftState propagate(final AbsoluteDate target) {
  394.         if (getStartDate() == null) {
  395.             if (getInitialState() == null) {
  396.                 throw new OrekitException(OrekitMessages.INITIAL_STATE_NOT_SPECIFIED_FOR_ORBIT_PROPAGATION);
  397.             }
  398.             setStartDate(getInitialState().getDate());
  399.         }
  400.         return propagate(getStartDate(), target);
  401.     }

  403.     /** {@inheritDoc} */
  404.     public SpacecraftState propagate(final AbsoluteDate tStart, final AbsoluteDate tEnd) {

  406.         if (getInitialState() == null) {
  407.             throw new OrekitException(OrekitMessages.INITIAL_STATE_NOT_SPECIFIED_FOR_ORBIT_PROPAGATION);
  408.         }

  410.         // make sure the integrator will be reset properly even if we change its events handlers and step handlers
  411.         try (IntegratorResetter resetter = new IntegratorResetter(integrator)) {

  413.             // prepare handling of STM and Jacobian matrices
  414.             setUpStmAndJacobianGenerators();

  416.             // Initialize additional states
  417.             initializeAdditionalStates(tEnd);

  419.             if (!tStart.equals(getInitialState().getDate())) {
  420.                 // if propagation start date is not initial date,
  421.                 // propagate from initial to start date without event detection
  422.                 try (IntegratorResetter startResetter = new IntegratorResetter(integrator)) {
  423.                     integrateDynamics(tStart, true);
  424.                 }
  425.             }

  427.             // set up events added by user
  428.             setUpUserEventDetectors();

  430.             // set up step handlers
  431.             for (final OrekitStepHandler handler : getMultiplexer().getHandlers()) {
  432.                 integrator.addStepHandler(new AdaptedStepHandler(handler));
  433.             }
  434.             for (final StoringStepHandler generator : ephemerisGenerators) {
  435.                 generator.setEndDate(tEnd);
  436.                 integrator.addStepHandler(generator);
  437.             }

  439.             // propagate from start date to end date with event detection
  440.             final SpacecraftState finalState = integrateDynamics(tEnd, false);

  442.             // Finalize event detectors
  443.             getEventsDetectors().forEach(detector -> detector.finish(finalState));

  445.             return finalState;
  446.         }

  448.     }

  450.     /** Reset initial state with a given propagation type.
  451.      *
  452.      * <p> By default this method returns the same as {@link #resetInitialState(SpacecraftState)}
  453.      * <p> Its purpose is mostly to be derived in DSSTPropagator
  454.      *
  455.      * @param state new initial state to consider
  456.      * @param stateType type of the new state (mean or osculating)
  457.      * @since 12.1.3
  458.      */
  459.     public void resetInitialState(final SpacecraftState state, final PropagationType stateType) {
  460.         // Default behavior, do not take propagation type into account
  461.         resetInitialState(state);
  462.     }

  464.     /** Set up State Transition Matrix and Jacobian matrix handling.
  465.      * @since 11.1
  466.      */
  467.     protected void setUpStmAndJacobianGenerators() {
  468.         // nothing to do by default
  469.     }

  471.     /** Propagation with or without event detection.
  472.      * @param tEnd target date to which orbit should be propagated
  473.      * @param forceResetAtEnd flag to force resetting state and date after integration
  474.      * @return state at end of propagation
  475.      */
  476.     private SpacecraftState integrateDynamics(final AbsoluteDate tEnd, final boolean forceResetAtEnd) {
  477.         try {

  479.             initializePropagation();

  481.             if (getInitialState().getDate().equals(tEnd)) {
  482.                 // don't extrapolate
  483.                 return getInitialState();
  484.             }

  486.             // space dynamics view
  487.             stateMapper = createMapper(getInitialState().getDate(), stateMapper.getMu(),
  488.                                        stateMapper.getOrbitType(), stateMapper.getPositionAngleType(),
  489.                                        stateMapper.getAttitudeProvider(), getInitialState().getFrame());
  490.             attitudeProviderForDerivatives = initializeAttitudeProviderForDerivatives();

  492.             if (Double.isNaN(getMu())) {
  493.                 setMu(getInitialState().getMu());
  494.             }

  496.             if (getInitialState().getMass() <= 0.0) {
  497.                 throw new OrekitException(OrekitMessages.NOT_POSITIVE_SPACECRAFT_MASS,
  498.                                           getInitialState().getMass());
  499.             }

  501.             // convert space flight dynamics API to math API
  502.             final SpacecraftState initialIntegrationState = getInitialIntegrationState();
  503.             final ODEState mathInitialState = createInitialState(initialIntegrationState);
  504.             final ExpandableODE mathODE = createODE(integrator);

  506.             // mathematical integration
  507.             final ODEStateAndDerivative mathFinalState;
  508.             beforeIntegration(initialIntegrationState, tEnd);
  509.             mathFinalState = integrator.integrate(mathODE, mathInitialState,
  510.                                                   tEnd.durationFrom(getInitialState().getDate()));
  511.             afterIntegration();

  513.             // get final state
  514.             SpacecraftState finalState =
  515.                             stateMapper.mapArrayToState(stateMapper.mapDoubleToDate(mathFinalState.getTime(),
  516.                                                                                     tEnd),
  517.                                                         mathFinalState.getPrimaryState(),
  518.                                                         mathFinalState.getPrimaryDerivative(),
  519.                                                         propagationType);

  521.             finalState = updateAdditionalStatesAndDerivatives(finalState, mathFinalState);

  523.             if (resetAtEnd || forceResetAtEnd) {
  524.                 resetInitialState(finalState, propagationType);
  525.                 setStartDate(finalState.getDate());
  526.             }

  528.             return finalState;

  530.         } catch (MathRuntimeException mre) {
  531.             throw OrekitException.unwrap(mre);
  532.         }
  533.     }

  535.     /**
  536.      * Returns an updated version of the inputted state with additional states, including
  537.      * from derivatives providers.
  538.      * @param originalState input state
  539.      * @param os ODE state and derivative
  540.      * @return new state
  541.      * @since 12.1
  542.      */
  543.     private SpacecraftState updateAdditionalStatesAndDerivatives(final SpacecraftState originalState,
  544.                                                                  final ODEStateAndDerivative os) {
  545.         SpacecraftState updatedState = originalState;
  546.         if (os.getNumberOfSecondaryStates() > 0) {
  547.             final double[] secondary           = os.getSecondaryState(1);
  548.             final double[] secondaryDerivative = os.getSecondaryDerivative(1);
  549.             for (final AdditionalDerivativesProvider provider : additionalDerivativesProviders) {
  550.                 final String name      = provider.getName();
  551.                 final int    offset    = secondaryOffsets.get(name);
  552.                 final int    dimension = provider.getDimension();
  553.                 updatedState = updatedState.addAdditionalState(name, Arrays.copyOfRange(secondary, offset, offset + dimension));
  554.                 updatedState = updatedState.addAdditionalStateDerivative(name, Arrays.copyOfRange(secondaryDerivative, offset, offset + dimension));
  555.             }
  556.         }
  557.         return updateAdditionalStates(updatedState);
  558.     }

  560.     /** Get the initial state for integration.
  561.      * @return initial state for integration
  562.      */
  563.     protected SpacecraftState getInitialIntegrationState() {
  564.         return getInitialState();
  565.     }

  567.     /** Create an initial state.
  568.      * @param initialState initial state in flight dynamics world
  569.      * @return initial state in mathematics world
  570.      */
  571.     private ODEState createInitialState(final SpacecraftState initialState) {

  573.         // retrieve initial state
  574.         final double[] primary = new double[getBasicDimension()];
  575.         stateMapper.mapStateToArray(initialState, primary, null);

  577.         if (secondaryOffsets.isEmpty()) {
  578.             // compute dimension of the secondary state
  579.             int offset = 0;
  580.             for (final AdditionalDerivativesProvider provider : additionalDerivativesProviders) {
  581.                 secondaryOffsets.put(provider.getName(), offset);
  582.                 offset += provider.getDimension();
  583.             }
  584.             secondaryOffsets.put(SECONDARY_DIMENSION, offset);
  585.         }

  587.         return new ODEState(0.0, primary, secondary(initialState));

  589.     }

  591.     /** Create secondary state.
  592.      * @param state spacecraft state
  593.      * @return secondary state
  594.      * @since 11.1
  595.      */
  596.     private double[][] secondary(final SpacecraftState state) {

  598.         if (secondaryOffsets.isEmpty()) {
  599.             return null;
  600.         }

  602.         final double[][] secondary = new double[1][secondaryOffsets.get(SECONDARY_DIMENSION)];
  603.         for (final AdditionalDerivativesProvider provider : additionalDerivativesProviders) {
  604.             final String   name       = provider.getName();
  605.             final int      offset     = secondaryOffsets.get(name);
  606.             final double[] additional = state.getAdditionalState(name);
  607.             System.arraycopy(additional, 0, secondary[0], offset, additional.length);
  608.         }

  610.         return secondary;

  612.     }

  614.     /** Create secondary state derivative.
  615.      * @param state spacecraft state
  616.      * @return secondary state derivative
  617.      * @since 11.1
  618.      */
  619.     private double[][] secondaryDerivative(final SpacecraftState state) {

  621.         if (secondaryOffsets.isEmpty()) {
  622.             return null;
  623.         }

  625.         final double[][] secondaryDerivative = new double[1][secondaryOffsets.get(SECONDARY_DIMENSION)];
  626.         for (final AdditionalDerivativesProvider provider : additionalDerivativesProviders) {
  627.             final String   name       = provider.getName();
  628.             final int      offset     = secondaryOffsets.get(name);
  629.             final double[] additionalDerivative = state.getAdditionalStateDerivative(name);
  630.             System.arraycopy(additionalDerivative, 0, secondaryDerivative[0], offset, additionalDerivative.length);
  631.         }

  633.         return secondaryDerivative;

  635.     }

  637.     /** Create an ODE with all equations.
  638.      * @param integ numerical integrator to use for propagation.
  639.      * @return a new ode
  640.      */
  641.     private ExpandableODE createODE(final ODEIntegrator integ) {

  643.         final ExpandableODE ode =
  644.                 new ExpandableODE(new ConvertedMainStateEquations(getMainStateEquations(integ)));

  646.         // secondary part of the ODE
  647.         if (!additionalDerivativesProviders.isEmpty()) {
  648.             ode.addSecondaryEquations(new ConvertedSecondaryStateEquations());
  649.         }

  651.         return ode;

  653.     }

  655.     /** Method called just before integration.
  656.      * <p>
  657.      * The default implementation does nothing, it may be specialized in subclasses.
  658.      * </p>
  659.      * @param initialState initial state
  660.      * @param tEnd target date at which state should be propagated
  661.      */
  662.     protected void beforeIntegration(final SpacecraftState initialState,
  663.                                      final AbsoluteDate tEnd) {
  664.         // do nothing by default
  665.     }

  667.     /** Method called just after integration.
  668.      * <p>
  669.      * The default implementation does nothing, it may be specialized in subclasses.
  670.      * </p>
  671.      */
  672.     protected void afterIntegration() {
  673.         // do nothing by default
  674.     }

  676.     /** Get state vector dimension without additional parameters.
  677.      * @return state vector dimension without additional parameters.
  678.      */
  679.     public int getBasicDimension() {
  680.         return 7;
  681.     }

  683.     /** Get the integrator used by the propagator.
  684.      * @return the integrator.
  685.      */
  686.     protected ODEIntegrator getIntegrator() {
  687.         return integrator;
  688.     }

  690.     /** Convert a state from mathematical world to space flight dynamics world.
  691.      * @param os mathematical state
  692.      * @return space flight dynamics state
  693.      */
  694.     private SpacecraftState convert(final ODEStateAndDerivative os) {

  696.         final SpacecraftState s = stateMapper.mapArrayToState(os.getTime(), os.getPrimaryState(),
  697.             os.getPrimaryDerivative(), propagationType);
  698.         return updateAdditionalStatesAndDerivatives(s, os);
  699.     }

  701.     /** Convert a state from space flight dynamics world to mathematical world.
  702.      * @param state space flight dynamics state
  703.      * @return mathematical state
  704.      */
  705.     private ODEStateAndDerivative convert(final SpacecraftState state) {

  707.         // retrieve initial state
  708.         final double[] primary    = new double[getBasicDimension()];
  709.         final double[] primaryDot = new double[getBasicDimension()];
  710.         stateMapper.mapStateToArray(state, primary, primaryDot);

  712.         // secondary part of the ODE
  713.         final double[][] secondary           = secondary(state);
  714.         final double[][] secondaryDerivative = secondaryDerivative(state);

  716.         return new ODEStateAndDerivative(stateMapper.mapDateToDouble(state.getDate()),
  717.                                          primary, primaryDot,
  718.                                          secondary, secondaryDerivative);

  720.     }

  722.     /** Differential equations for the main state (orbit, attitude and mass). */
  723.     public interface MainStateEquations {

  725.         /**
  726.          * Initialize the equations at the start of propagation. This method will be
  727.          * called before any calls to {@link #computeDerivatives(SpacecraftState)}.
  728.          *
  729.          * <p> The default implementation of this method does nothing.
  730.          *
  731.          * @param initialState initial state information at the start of propagation.
  732.          * @param target       date of propagation. Not equal to {@code
  733.          *                     initialState.getDate()}.
  734.          */
  735.         default void init(final SpacecraftState initialState, final AbsoluteDate target) {
  736.         }

  738.         /** Compute differential equations for main state.
  739.          * @param state current state
  740.          * @return derivatives of main state
  741.          */
  742.         double[] computeDerivatives(SpacecraftState state);

  744.     }

  746.     /** Differential equations for the main state (orbit, attitude and mass), with converted API. */
  747.     private class ConvertedMainStateEquations implements OrdinaryDifferentialEquation {

  749.         /** Main state equations. */
  750.         private final MainStateEquations main;

  752.         /** Simple constructor.
  753.          * @param main main state equations
  754.          */
  755.         ConvertedMainStateEquations(final MainStateEquations main) {
  756.             this.main = main;
  757.             calls = 0;
  758.         }

  760.         /** {@inheritDoc} */
  761.         public int getDimension() {
  762.             return getBasicDimension();
  763.         }

  765.         @Override
  766.         public void init(final double t0, final double[] y0, final double finalTime) {
  767.             // update space dynamics view
  768.             SpacecraftState initialState = stateMapper.mapArrayToState(t0, y0, null, PropagationType.MEAN);
  769.             initialState = updateAdditionalStates(initialState);
  770.             initialState = updateStatesFromAdditionalDerivativesIfKnown(initialState);
  771.             final AbsoluteDate target = stateMapper.mapDoubleToDate(finalTime);
  772.             main.init(initialState, target);
  773.             attitudeProviderForDerivatives = initializeAttitudeProviderForDerivatives();
  774.         }

  776.         /**
  777.          * Returns an updated version of the inputted state, with additional states from
  778.          * derivatives providers as given in the stored initial state.
  779.          * @param originalState input state
  780.          * @return new state
  781.          * @since 12.1
  782.          */
  783.         private SpacecraftState updateStatesFromAdditionalDerivativesIfKnown(final SpacecraftState originalState) {
  784.             SpacecraftState updatedState = originalState;
  785.             final SpacecraftState storedInitialState = getInitialState();
  786.             final double originalTime = stateMapper.mapDateToDouble(originalState.getDate());
  787.             if (storedInitialState != null && stateMapper.mapDateToDouble(storedInitialState.getDate()) == originalTime) {
  788.                 for (final AdditionalDerivativesProvider provider: additionalDerivativesProviders) {
  789.                     final String name = provider.getName();
  790.                     final double[] value = storedInitialState.getAdditionalState(name);
  791.                     updatedState = updatedState.addAdditionalState(name, value);
  792.                 }
  793.             }
  794.             return updatedState;
  795.         }

  797.         /** {@inheritDoc} */
  798.         public double[] computeDerivatives(final double t, final double[] y) {

  800.             // increment calls counter
  801.             ++calls;

  803.             // update space dynamics view
  804.             stateMapper.setAttitudeProvider(attitudeProviderForDerivatives);
  805.             SpacecraftState currentState = stateMapper.mapArrayToState(t, y, null, PropagationType.MEAN);
  806.             stateMapper.setAttitudeProvider(getAttitudeProvider());

  808.             currentState = updateAdditionalStates(currentState);
  809.             // compute main state differentials
  810.             return main.computeDerivatives(currentState);

  812.         }

  814.     }

  816.     /** Differential equations for the secondary state (Jacobians, user variables ...), with converted API. */
  817.     private class ConvertedSecondaryStateEquations implements SecondaryODE {

  819.         /** Dimension of the combined additional states. */
  820.         private final int combinedDimension;

  822.         /** Simple constructor.
  823.           */
  824.         ConvertedSecondaryStateEquations() {
  825.             this.combinedDimension = secondaryOffsets.get(SECONDARY_DIMENSION);
  826.         }

  828.         /** {@inheritDoc} */
  829.         @Override
  830.         public int getDimension() {
  831.             return combinedDimension;
  832.         }

  834.         /** {@inheritDoc} */
  835.         @Override
  836.         public void init(final double t0, final double[] primary0,
  837.                          final double[] secondary0, final double finalTime) {
  838.             // update space dynamics view
  839.             final SpacecraftState initialState = convert(t0, primary0, null, secondary0);

  841.             final AbsoluteDate target = stateMapper.mapDoubleToDate(finalTime);
  842.             for (final AdditionalDerivativesProvider provider : additionalDerivativesProviders) {
  843.                 provider.init(initialState, target);
  844.             }

  846.         }

  848.         /** {@inheritDoc} */
  849.         @Override
  850.         public double[] computeDerivatives(final double t, final double[] primary,
  851.                                            final double[] primaryDot, final double[] secondary) {

  853.             // update space dynamics view
  854.             // the integrable generators generate method will be called here,
  855.             // according to the generators yield order
  856.             SpacecraftState updated = convert(t, primary, primaryDot, secondary);

  858.             // set up queue for equations
  859.             final Queue<AdditionalDerivativesProvider> pending = new LinkedList<>(additionalDerivativesProviders);

  861.             // gather the derivatives from all additional equations, taking care of dependencies
  862.             final double[] secondaryDot = new double[combinedDimension];
  863.             int yieldCount = 0;
  864.             while (!pending.isEmpty()) {
  865.                 final AdditionalDerivativesProvider provider = pending.remove();
  866.                 if (provider.yields(updated)) {
  867.                     // this provider has to wait for another one,
  868.                     // we put it again in the pending queue
  869.                     pending.add(provider);
  870.                     if (++yieldCount >= pending.size()) {
  871.                         // all pending providers yielded!, they probably need data not yet initialized
  872.                         // we let the propagation proceed, if these data are really needed right now
  873.                         // an appropriate exception will be triggered when caller tries to access them
  874.                         break;
  875.                     }
  876.                 } else {
  877.                     // we can use these equations right now
  878.                     final String              name           = provider.getName();
  879.                     final int                 offset         = secondaryOffsets.get(name);
  880.                     final int                 dimension      = provider.getDimension();
  881.                     final CombinedDerivatives derivatives    = provider.combinedDerivatives(updated);
  882.                     final double[]            additionalPart = derivatives.getAdditionalDerivatives();
  883.                     final double[]            mainPart       = derivatives.getMainStateDerivativesIncrements();
  884.                     System.arraycopy(additionalPart, 0, secondaryDot, offset, dimension);
  885.                     updated = updated.addAdditionalStateDerivative(name, additionalPart);
  886.                     if (mainPart != null) {
  887.                         // this equation does change the main state derivatives
  888.                         for (int i = 0; i < mainPart.length; ++i) {
  889.                             primaryDot[i] += mainPart[i];
  890.                         }
  891.                     }
  892.                     yieldCount = 0;
  893.                 }
  894.             }

  896.             return secondaryDot;

  898.         }

  900.         /** Convert mathematical view to space view.
  901.          * @param t current value of the independent <I>time</I> variable
  902.          * @param primary array containing the current value of the primary state vector
  903.          * @param primaryDot array containing the derivative of the primary state vector
  904.          * @param secondary array containing the current value of the secondary state vector
  905.          * @return space view of the state
  906.          */
  907.         private SpacecraftState convert(final double t, final double[] primary,
  908.                                         final double[] primaryDot, final double[] secondary) {

  910.             SpacecraftState initialState = stateMapper.mapArrayToState(t, primary, primaryDot, PropagationType.MEAN);

  912.             for (final AdditionalDerivativesProvider provider : additionalDerivativesProviders) {
  913.                 final String name      = provider.getName();
  914.                 final int    offset    = secondaryOffsets.get(name);
  915.                 final int    dimension = provider.getDimension();
  916.                 initialState = initialState.addAdditionalState(name, Arrays.copyOfRange(secondary, offset, offset + dimension));
  917.             }

  919.             return updateAdditionalStates(initialState);

  921.         }

  923.     }

  925.     /** Adapt an {@link org.orekit.propagation.events.EventDetector}
  926.      * to Hipparchus {@link org.hipparchus.ode.events.ODEEventDetector} interface.
  927.      * @author Fabien Maussion
  928.      */
  929.     private class AdaptedEventDetector implements ODEEventDetector {

  931.         /** Underlying event detector. */
  932.         private final EventDetector detector;

  934.         /** Underlying event handler.
  935.          * @since 12.0
  936.          */
  937.         private final EventHandler handler;

  939.         /** Time of the previous call to g. */
  940.         private double lastT;

  942.         /** Value from the previous call to g. */
  943.         private double lastG;

  945.         /** Build a wrapped event detector.
  946.          * @param detector event detector to wrap
  947.         */
  948.         AdaptedEventDetector(final EventDetector detector) {
  949.             this.detector = detector;
  950.             this.handler  = detector.getHandler();
  951.             this.lastT    = Double.NaN;
  952.             this.lastG    = Double.NaN;
  953.         }

  955.         /** {@inheritDoc} */
  956.         @Override
  957.         public AdaptableInterval getMaxCheckInterval() {
  958.             return s -> detector.getMaxCheckInterval().currentInterval(convert(s));
  959.         }

  961.         /** {@inheritDoc} */
  962.         @Override
  963.         public int getMaxIterationCount() {
  964.             return detector.getMaxIterationCount();
  965.         }

  967.         /** {@inheritDoc} */
  968.         @Override
  969.         public BracketedUnivariateSolver<UnivariateFunction> getSolver() {
  970.             return new BracketingNthOrderBrentSolver(0, detector.getThreshold(), 0, 5);
  971.         }

  973.         /** {@inheritDoc} */
  974.         @Override
  975.         public void init(final ODEStateAndDerivative s0, final double t) {
  976.             detector.init(convert(s0), stateMapper.mapDoubleToDate(t));
  977.             this.lastT = Double.NaN;
  978.             this.lastG = Double.NaN;
  979.         }

  981.         /** {@inheritDoc} */
  982.         public double g(final ODEStateAndDerivative s) {
  983.             if (!Precision.equals(lastT, s.getTime(), 0)) {
  984.                 lastT = s.getTime();
  985.                 lastG = detector.g(convert(s));
  986.             }
  987.             return lastG;
  988.         }

  990.         /** {@inheritDoc} */
  991.         public ODEEventHandler getHandler() {

  993.             return new ODEEventHandler() {

  995.                 /** {@inheritDoc} */
  996.                 public Action eventOccurred(final ODEStateAndDerivative s, final ODEEventDetector d, final boolean increasing) {
  997.                     return handler.eventOccurred(convert(s), detector, increasing);
  998.                 }

  1000.                 /** {@inheritDoc} */
  1001.                 @Override
  1002.                 public ODEState resetState(final ODEEventDetector d, final ODEStateAndDerivative s) {

  1004.                     final SpacecraftState oldState = convert(s);
  1005.                     final SpacecraftState newState = handler.resetState(detector, oldState);
  1006.                     stateChanged(newState);

  1008.                     // main part
  1009.                     final double[] primary    = new double[s.getPrimaryStateDimension()];
  1010.                     stateMapper.mapStateToArray(newState, primary, null);

  1012.                     // secondary part
  1013.                     final double[][] secondary = new double[1][secondaryOffsets.get(SECONDARY_DIMENSION)];
  1014.                     for (final AdditionalDerivativesProvider provider : additionalDerivativesProviders) {
  1015.                         final String name      = provider.getName();
  1016.                         final int    offset    = secondaryOffsets.get(name);
  1017.                         final int    dimension = provider.getDimension();
  1018.                         System.arraycopy(newState.getAdditionalState(name), 0, secondary[0], offset, dimension);
  1019.                     }

  1021.                     return new ODEState(newState.getDate().durationFrom(getStartDate()),
  1022.                                         primary, secondary);

  1024.                 }

  1026.             };
  1027.         }

  1029.     }

  1031.     /** Adapt an {@link org.orekit.propagation.sampling.OrekitStepHandler}
  1032.      * to Hipparchus {@link ODEStepHandler} interface.
  1033.      * @author Luc Maisonobe
  1034.      */
  1035.     private class AdaptedStepHandler implements ODEStepHandler {

  1037.         /** Underlying handler. */
  1038.         private final OrekitStepHandler handler;

  1040.         /** Build an instance.
  1041.          * @param handler underlying handler to wrap
  1042.          */
  1043.         AdaptedStepHandler(final OrekitStepHandler handler) {
  1044.             this.handler = handler;
  1045.         }

  1047.         /** {@inheritDoc} */
  1048.         @Override
  1049.         public void init(final ODEStateAndDerivative s0, final double t) {
  1050.             handler.init(convert(s0), stateMapper.mapDoubleToDate(t));
  1051.         }

  1053.         /** {@inheritDoc} */
  1054.         @Override
  1055.         public void handleStep(final ODEStateInterpolator interpolator) {
  1056.             handler.handleStep(new AdaptedStepInterpolator(interpolator));
  1057.         }

  1059.         /** {@inheritDoc} */
  1060.         @Override
  1061.         public void finish(final ODEStateAndDerivative finalState) {
  1062.             handler.finish(convert(finalState));
  1063.         }

  1065.     }

  1067.     /** Adapt an Hipparchus {@link ODEStateInterpolator}
  1068.      * to an orekit {@link OrekitStepInterpolator} interface.
  1069.      * @author Luc Maisonobe
  1070.      */
  1071.     private class AdaptedStepInterpolator implements OrekitStepInterpolator {

  1073.         /** Underlying raw rawInterpolator. */
  1074.         private final ODEStateInterpolator mathInterpolator;

  1076.         /** Simple constructor.
  1077.          * @param mathInterpolator underlying raw interpolator
  1078.          */
  1079.         AdaptedStepInterpolator(final ODEStateInterpolator mathInterpolator) {
  1080.             this.mathInterpolator = mathInterpolator;
  1081.         }

  1083.         /** {@inheritDoc}} */
  1084.         @Override
  1085.         public SpacecraftState getPreviousState() {
  1086.             return convert(mathInterpolator.getPreviousState());
  1087.         }

  1089.         /** {@inheritDoc}} */
  1090.         @Override
  1091.         public boolean isPreviousStateInterpolated() {
  1092.             return mathInterpolator.isPreviousStateInterpolated();
  1093.         }

  1095.         /** {@inheritDoc}} */
  1096.         @Override
  1097.         public SpacecraftState getCurrentState() {
  1098.             return convert(mathInterpolator.getCurrentState());
  1099.         }

  1101.         /** {@inheritDoc}} */
  1102.         @Override
  1103.         public boolean isCurrentStateInterpolated() {
  1104.             return mathInterpolator.isCurrentStateInterpolated();
  1105.         }

  1107.         /** {@inheritDoc}} */
  1108.         @Override
  1109.         public SpacecraftState getInterpolatedState(final AbsoluteDate date) {
  1110.             return convert(mathInterpolator.getInterpolatedState(date.durationFrom(stateMapper.getReferenceDate())));
  1111.         }

  1113.         /** {@inheritDoc}} */
  1114.         @Override
  1115.         public boolean isForward() {
  1116.             return mathInterpolator.isForward();
  1117.         }

  1119.         /** {@inheritDoc}} */
  1120.         @Override
  1121.         public AdaptedStepInterpolator restrictStep(final SpacecraftState newPreviousState,
  1122.                                                     final SpacecraftState newCurrentState) {
  1123.             try {
  1124.                 final AbstractODEStateInterpolator aosi = (AbstractODEStateInterpolator) mathInterpolator;
  1125.                 return new AdaptedStepInterpolator(aosi.restrictStep(convert(newPreviousState),
  1126.                                                                      convert(newCurrentState)));
  1127.             } catch (ClassCastException cce) {
  1128.                 // this should never happen
  1129.                 throw new OrekitInternalError(cce);
  1130.             }
  1131.         }

  1133.     }

  1135.     /** Specialized step handler storing interpolators for ephemeris generation.
  1136.      * @since 11.0
  1137.      */
  1138.     private class StoringStepHandler implements ODEStepHandler, EphemerisGenerator {

  1140.         /** Underlying raw mathematical model. */
  1141.         private DenseOutputModel model;

  1143.         /** the user supplied end date. Propagation may not end on this date. */
  1144.         private AbsoluteDate endDate;

  1146.         /** Generated ephemeris. */
  1147.         private BoundedPropagator ephemeris;

  1149.         /** Last interpolator handled by the object.*/
  1150.         private  ODEStateInterpolator lastInterpolator;

  1152.         /** Set the end date.
  1153.          * @param endDate end date
  1154.          */
  1155.         public void setEndDate(final AbsoluteDate endDate) {
  1156.             this.endDate = endDate;
  1157.         }

  1159.         /** {@inheritDoc} */
  1160.         @Override
  1161.         public void init(final ODEStateAndDerivative s0, final double t) {

  1163.             this.model = new DenseOutputModel();
  1164.             model.init(s0, t);

  1166.             // ephemeris will be generated when last step is processed
  1167.             this.ephemeris = null;

  1169.             this.lastInterpolator = null;

  1171.         }

  1173.         /** {@inheritDoc} */
  1174.         @Override
  1175.         public BoundedPropagator getGeneratedEphemeris() {
  1176.             // Each time we try to get the ephemeris, rebuild it using the last data.
  1177.             buildEphemeris();
  1178.             return ephemeris;
  1179.         }

  1181.         /** {@inheritDoc} */
  1182.         @Override
  1183.         public void handleStep(final ODEStateInterpolator interpolator) {
  1184.             model.handleStep(interpolator);
  1185.             lastInterpolator = interpolator;
  1186.         }

  1188.         /** {@inheritDoc} */
  1189.         @Override
  1190.         public void finish(final ODEStateAndDerivative finalState) {
  1191.             buildEphemeris();
  1192.         }

  1194.         /** Method used to produce ephemeris at a given time.
  1195.          * Can be used at multiple times, updating the ephemeris to
  1196.          * its last state.
  1197.          */
  1198.         private void buildEphemeris() {
  1199.             // buildEphemeris was built in order to allow access to what was previously the finish method.
  1200.             // This now allows to call it through getGeneratedEphemeris, therefore through an external call,
  1201.             // which was not previously the case.

  1203.             // Update the model's finalTime with the last interpolator.
  1204.             model.finish(lastInterpolator.getCurrentState());

  1206.             // set up the boundary dates
  1207.             final double tI = model.getInitialTime();
  1208.             final double tF = model.getFinalTime();
  1209.             // tI is almost? always zero
  1210.             final AbsoluteDate startDate =
  1211.                             stateMapper.mapDoubleToDate(tI);
  1212.             final AbsoluteDate finalDate =
  1213.                             stateMapper.mapDoubleToDate(tF, this.endDate);
  1214.             final AbsoluteDate minDate;
  1215.             final AbsoluteDate maxDate;
  1216.             if (tF < tI) {
  1217.                 minDate = finalDate;
  1218.                 maxDate = startDate;
  1219.             } else {
  1220.                 minDate = startDate;
  1221.                 maxDate = finalDate;
  1222.             }

  1224.             // get the initial additional states that are not managed
  1225.             final DoubleArrayDictionary unmanaged = new DoubleArrayDictionary();
  1226.             for (final DoubleArrayDictionary.Entry initial : getInitialState().getAdditionalStatesValues().getData()) {
  1227.                 if (!isAdditionalStateManaged(initial.getKey())) {
  1228.                     // this additional state was in the initial state, but is unknown to the propagator
  1229.                     // we simply copy its initial value as is
  1230.                     unmanaged.put(initial.getKey(), initial.getValue());
  1231.                 }
  1232.             }

  1234.             // get the names of additional states managed by differential equations
  1235.             final String[] names      = new String[additionalDerivativesProviders.size()];
  1236.             final int[]    dimensions = new int[additionalDerivativesProviders.size()];
  1237.             for (int i = 0; i < names.length; ++i) {
  1238.                 names[i] = additionalDerivativesProviders.get(i).getName();
  1239.                 dimensions[i] = additionalDerivativesProviders.get(i).getDimension();
  1240.             }

  1242.             // create the ephemeris
  1243.             ephemeris = new IntegratedEphemeris(startDate, minDate, maxDate,
  1244.                                                 stateMapper, propagationType, model,
  1245.                                                 unmanaged, getAdditionalStateProviders(),
  1246.                                                 names, dimensions);

  1248.         }

  1250.     }

  1252.     /** Wrapper for resetting an integrator handlers.
  1253.      * <p>
  1254.      * This class is intended to be used in a try-with-resource statement.
  1255.      * If propagator-specific event handlers and step handlers are added to
  1256.      * the integrator in the try block, they will be removed automatically
  1257.      * when leaving the block, so the integrator only keeps its own handlers
  1258.      * between calls to {@link AbstractIntegratedPropagator#propagate(AbsoluteDate, AbsoluteDate).
  1259.      * </p>
  1260.      * @since 11.0
  1261.      */
  1262.     private static class IntegratorResetter implements AutoCloseable {

  1264.         /** Wrapped integrator. */
  1265.         private final ODEIntegrator integrator;

  1267.         /** Initial event detectors list. */
  1268.         private final List<ODEEventDetector> detectors;

  1270.         /** Initial step handlers list. */
  1271.         private final List<ODEStepHandler> stepHandlers;

  1273.         /** Simple constructor.
  1274.          * @param integrator wrapped integrator
  1275.          */
  1276.         IntegratorResetter(final ODEIntegrator integrator) {
  1277.             this.integrator   = integrator;
  1278.             this.detectors    = new ArrayList<>(integrator.getEventDetectors());
  1279.             this.stepHandlers = new ArrayList<>(integrator.getStepHandlers());
  1280.         }

  1282.         /** {@inheritDoc}
  1283.          * <p>
  1284.          * Reset event handlers and step handlers back to the initial list
  1285.          * </p>
  1286.          */
  1287.         @Override
  1288.         public void close() {

  1290.             // reset event handlers
  1291.             integrator.clearEventDetectors();
  1292.             detectors.forEach(integrator::addEventDetector);

  1294.             // reset step handlers
  1295.             integrator.clearStepHandlers();
  1296.             stepHandlers.forEach(integrator::addStepHandler);

  1298.         }

  1300.     }

  1302. }
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