AbstractPropagator.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;

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

  27. import org.hipparchus.linear.RealMatrix;
  28. import org.orekit.attitudes.AttitudeProvider;
  29. import org.orekit.errors.OrekitException;
  30. import org.orekit.errors.OrekitMessages;
  31. import org.orekit.frames.Frame;
  32. import org.orekit.propagation.sampling.StepHandlerMultiplexer;
  33. import org.orekit.time.AbsoluteDate;
  34. import org.orekit.utils.DoubleArrayDictionary;
  35. import org.orekit.utils.TimeSpanMap;

  37. /** Common handling of {@link Propagator} methods for analytical propagators.
  38.  * <p>
  39.  * This abstract class allows to provide easily the full set of {@link Propagator}
  40.  * methods, including all propagation modes support and discrete events support for
  41.  * any simple propagation method.
  42.  * </p>
  43.  * @author Luc Maisonobe
  44.  */
  45. public abstract class AbstractPropagator implements Propagator {

  47.     /** Multiplexer for step handlers. */
  48.     private final StepHandlerMultiplexer multiplexer;

  50.     /** Start date. */
  51.     private AbsoluteDate startDate;

  53.     /** Attitude provider. */
  54.     private AttitudeProvider attitudeProvider;

  56.     /** Providers for additional states. */
  57.     private final List<AdditionalStateProvider> additionalStateProviders;

  59.     /** States managed by no generators. */
  60.     private final Map<String, TimeSpanMap<double[]>> unmanagedStates;

  62.     /** Initial state. */
  63.     private SpacecraftState initialState;

  65.     /** Harvester for State Transition Matrix and Jacobian matrix. */
  66.     private AbstractMatricesHarvester harvester;

  68.     /** Build a new instance.
  69.      */
  70.     protected AbstractPropagator() {
  71.         multiplexer              = new StepHandlerMultiplexer();
  72.         additionalStateProviders = new ArrayList<>();
  73.         unmanagedStates          = new HashMap<>();
  74.         harvester                = null;
  75.     }

  77.     /** Set a start date.
  78.      * @param startDate start date
  79.      */
  80.     protected void setStartDate(final AbsoluteDate startDate) {
  81.         this.startDate = startDate;
  82.     }

  84.     /** Get the start date.
  85.      * @return start date
  86.      */
  87.     protected AbsoluteDate getStartDate() {
  88.         return startDate;
  89.     }

  91.     /**  {@inheritDoc} */
  92.     public AttitudeProvider getAttitudeProvider() {
  93.         return attitudeProvider;
  94.     }

  96.     /**  {@inheritDoc} */
  97.     public void setAttitudeProvider(final AttitudeProvider attitudeProvider) {
  98.         this.attitudeProvider = attitudeProvider;
  99.     }

  101.     /** {@inheritDoc} */
  102.     public SpacecraftState getInitialState() {
  103.         return initialState;
  104.     }

  106.     /** {@inheritDoc} */
  107.     public Frame getFrame() {
  108.         return initialState.getFrame();
  109.     }

  111.     /** {@inheritDoc} */
  112.     public void resetInitialState(final SpacecraftState state) {
  113.         initialState = state;
  114.         setStartDate(state.getDate());
  115.     }

  117.     /** {@inheritDoc} */
  118.     public StepHandlerMultiplexer getMultiplexer() {
  119.         return multiplexer;
  120.     }

  122.     /** {@inheritDoc} */
  123.     @Override
  124.     public void addAdditionalStateProvider(final AdditionalStateProvider provider) {

  126.         // check if the name is already used
  127.         if (isAdditionalStateManaged(provider.getName())) {
  128.             // this additional state is already registered, complain
  129.             throw new OrekitException(OrekitMessages.ADDITIONAL_STATE_NAME_ALREADY_IN_USE,
  130.                                       provider.getName());
  131.         }

  133.         // this is really a new name, add it
  134.         additionalStateProviders.add(provider);

  136.     }

  138.     /** {@inheritDoc} */
  139.     @Override
  140.     public List<AdditionalStateProvider> getAdditionalStateProviders() {
  141.         return Collections.unmodifiableList(additionalStateProviders);
  142.     }

  144.     /** {@inheritDoc} */
  145.     @Override
  146.     public MatricesHarvester setupMatricesComputation(final String stmName, final RealMatrix initialStm,
  147.                                                       final DoubleArrayDictionary initialJacobianColumns) {
  148.         if (stmName == null) {
  149.             throw new OrekitException(OrekitMessages.NULL_ARGUMENT, "stmName");
  150.         }
  151.         harvester = createHarvester(stmName, initialStm, initialJacobianColumns);
  152.         return harvester;
  153.     }

  155.     /** Create the harvester suitable for propagator.
  156.      * @param stmName State Transition Matrix state name
  157.      * @param initialStm initial State Transition Matrix ∂Y/∂Y₀,
  158.      * if null (which is the most frequent case), assumed to be 6x6 identity
  159.      * @param initialJacobianColumns initial columns of the Jacobians matrix with respect to parameters,
  160.      * if null or if some selected parameters are missing from the dictionary, the corresponding
  161.      * initial column is assumed to be 0
  162.      * @return harvester to retrieve computed matrices during and after propagation
  163.      * @since 11.1
  164.      */
  165.     protected AbstractMatricesHarvester createHarvester(final String stmName, final RealMatrix initialStm,
  166.                                                         final DoubleArrayDictionary initialJacobianColumns) {
  167.         // FIXME: not implemented as of 11.1
  168.         throw new UnsupportedOperationException();
  169.     }

  171.     /** Get the harvester.
  172.      * @return harvester, or null if it was not created
  173.      * @since 11.1
  174.      */
  175.     protected AbstractMatricesHarvester getHarvester() {
  176.         return harvester;
  177.     }

  179.     /** Update state by adding unmanaged states.
  180.      * @param original original state
  181.      * @return updated state, with unmanaged states included
  182.      * @see #updateAdditionalStates(SpacecraftState)
  183.      */
  184.     protected SpacecraftState updateUnmanagedStates(final SpacecraftState original) {

  186.         // start with original state,
  187.         // which may already contain additional states, for example in interpolated ephemerides
  188.         SpacecraftState updated = original;

  190.         // update the states not managed by providers
  191.         for (final Map.Entry<String, TimeSpanMap<double[]>> entry : unmanagedStates.entrySet()) {
  192.             updated = updated.addAdditionalState(entry.getKey(),
  193.                                                  entry.getValue().get(original.getDate()));
  194.         }

  196.         return updated;

  198.     }

  200.     /** Update state by adding all additional states.
  201.      * @param original original state
  202.      * @return updated state, with all additional states included
  203.      * (including {@link #updateUnmanagedStates(SpacecraftState) unmanaged} states)
  204.      * @see #addAdditionalStateProvider(AdditionalStateProvider)
  205.      * @see #updateUnmanagedStates(SpacecraftState)
  206.      */
  207.     protected SpacecraftState updateAdditionalStates(final SpacecraftState original) {

  209.         // start with original state and unmanaged states
  210.         SpacecraftState updated = updateUnmanagedStates(original);

  212.         // set up queue for providers
  213.         final Queue<AdditionalStateProvider> pending = new LinkedList<>(getAdditionalStateProviders());

  215.         // update the additional states managed by providers, taking care of dependencies
  216.         int yieldCount = 0;
  217.         while (!pending.isEmpty()) {
  218.             final AdditionalStateProvider provider = pending.remove();
  219.             if (provider.yields(updated)) {
  220.                 // this generator has to wait for another one,
  221.                 // we put it again in the pending queue
  222.                 pending.add(provider);
  223.                 if (++yieldCount >= pending.size()) {
  224.                     // all pending providers yielded!, they probably need data not yet initialized
  225.                     // we let the propagation proceed, if these data are really needed right now
  226.                     // an appropriate exception will be triggered when caller tries to access them
  227.                     break;
  228.                 }
  229.             } else {
  230.                 // we can use this provider right now
  231.                 updated    = provider.update(updated);
  232.                 yieldCount = 0;
  233.             }
  234.         }

  236.         return updated;

  238.     }

  240.     /**
  241.      * Initialize the additional state providers at the start of propagation.
  242.      * @param target date of propagation. Not equal to {@code initialState.getDate()}.
  243.      * @since 11.2
  244.      */
  245.     protected void initializeAdditionalStates(final AbsoluteDate target) {
  246.         for (final AdditionalStateProvider provider : additionalStateProviders) {
  247.             provider.init(initialState, target);
  248.         }
  249.     }

  251.     /** {@inheritDoc} */
  252.     public boolean isAdditionalStateManaged(final String name) {
  253.         for (final AdditionalStateProvider provider : additionalStateProviders) {
  254.             if (provider.getName().equals(name)) {
  255.                 return true;
  256.             }
  257.         }
  258.         return false;
  259.     }

  261.     /** {@inheritDoc} */
  262.     public String[] getManagedAdditionalStates() {
  263.         final String[] managed = new String[additionalStateProviders.size()];
  264.         for (int i = 0; i < managed.length; ++i) {
  265.             managed[i] = additionalStateProviders.get(i).getName();
  266.         }
  267.         return managed;
  268.     }

  270.     /** {@inheritDoc} */
  271.     public SpacecraftState propagate(final AbsoluteDate target) {
  272.         if (startDate == null) {
  273.             startDate = getInitialState().getDate();
  274.         }
  275.         return propagate(startDate, target);
  276.     }

  278.     /** Initialize propagation.
  279.      * @since 10.1
  280.      */
  281.     protected void initializePropagation() {

  283.         unmanagedStates.clear();

  285.         if (initialState != null) {
  286.             // there is an initial state
  287.             // (null initial states occur for example in interpolated ephemerides)
  288.             // copy the additional states present in initialState but otherwise not managed
  289.             for (final DoubleArrayDictionary.Entry initial : initialState.getAdditionalStatesValues().getData()) {
  290.                 if (!isAdditionalStateManaged(initial.getKey())) {
  291.                     // this additional state is in the initial state, but is unknown to the propagator
  292.                     // we store it in a way event handlers may change it
  293.                     unmanagedStates.put(initial.getKey(), new TimeSpanMap<>(initial.getValue()));
  294.                 }
  295.             }
  296.         }
  297.     }

  299.     /** Notify about a state change.
  300.      * @param state new state
  301.      */
  302.     protected void stateChanged(final SpacecraftState state) {
  303.         final AbsoluteDate date    = state.getDate();
  304.         final boolean      forward = date.durationFrom(getStartDate()) >= 0.0;
  305.         for (final DoubleArrayDictionary.Entry changed : state.getAdditionalStatesValues().getData()) {
  306.             final TimeSpanMap<double[]> tsm = unmanagedStates.get(changed.getKey());
  307.             if (tsm != null) {
  308.                 // this is an unmanaged state
  309.                 if (forward) {
  310.                     tsm.addValidAfter(changed.getValue(), date, false);
  311.                 } else {
  312.                     tsm.addValidBefore(changed.getValue(), date, false);
  313.                 }
  314.             }
  315.         }
  316.     }

  318. }
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