AbstractPropagator.java

  1. /* Copyright 2002-2023 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;
  36. import org.orekit.utils.TimeStampedPVCoordinates;

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

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

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

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

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

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

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

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

  69.     /** Build a new instance.
  70.      */
  71.     protected AbstractPropagator() {
  72.         multiplexer              = new StepHandlerMultiplexer();
  73.         additionalStateProviders = new ArrayList<>();
  74.         unmanagedStates          = new HashMap<>();
  75.         harvester                = null;
  76.     }

  78.     /** Set a start date.
  79.      * @param startDate start date
  80.      */
  81.     protected void setStartDate(final AbsoluteDate startDate) {
  82.         this.startDate = startDate;
  83.     }

  85.     /** Get the start date.
  86.      * @return start date
  87.      */
  88.     protected AbsoluteDate getStartDate() {
  89.         return startDate;
  90.     }

  92.     /**  {@inheritDoc} */
  93.     public AttitudeProvider getAttitudeProvider() {
  94.         return attitudeProvider;
  95.     }

  97.     /**  {@inheritDoc} */
  98.     public void setAttitudeProvider(final AttitudeProvider attitudeProvider) {
  99.         this.attitudeProvider = attitudeProvider;
  100.     }

  102.     /** {@inheritDoc} */
  103.     public SpacecraftState getInitialState() {
  104.         return initialState;
  105.     }

  107.     /** {@inheritDoc} */
  108.     public Frame getFrame() {
  109.         return initialState.getFrame();
  110.     }

  112.     /** {@inheritDoc} */
  113.     public void resetInitialState(final SpacecraftState state) {
  114.         initialState = state;
  115.         setStartDate(state.getDate());
  116.     }

  118.     /** {@inheritDoc} */
  119.     public StepHandlerMultiplexer getMultiplexer() {
  120.         return multiplexer;
  121.     }

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

  127.         // check if the name is already used
  128.         if (isAdditionalStateManaged(provider.getName())) {
  129.             // this additional state is already registered, complain
  130.             throw new OrekitException(OrekitMessages.ADDITIONAL_STATE_NAME_ALREADY_IN_USE,
  131.                                       provider.getName());
  132.         }

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

  137.     }

  139.     /** {@inheritDoc} */
  140.     @Override
  141.     public List<AdditionalStateProvider> getAdditionalStateProviders() {
  142.         return Collections.unmodifiableList(additionalStateProviders);
  143.     }

  145.     /** {@inheritDoc} */
  146.     @Override
  147.     public MatricesHarvester setupMatricesComputation(final String stmName, final RealMatrix initialStm,
  148.                                                       final DoubleArrayDictionary initialJacobianColumns) {
  149.         if (stmName == null) {
  150.             throw new OrekitException(OrekitMessages.NULL_ARGUMENT, "stmName");
  151.         }
  152.         harvester = createHarvester(stmName, initialStm, initialJacobianColumns);
  153.         return harvester;
  154.     }

  156.     /** Create the harvester suitable for propagator.
  157.      * @param stmName State Transition Matrix state name
  158.      * @param initialStm initial State Transition Matrix ∂Y/∂Y₀,
  159.      * if null (which is the most frequent case), assumed to be 6x6 identity
  160.      * @param initialJacobianColumns initial columns of the Jacobians matrix with respect to parameters,
  161.      * if null or if some selected parameters are missing from the dictionary, the corresponding
  162.      * initial column is assumed to be 0
  163.      * @return harvester to retrieve computed matrices during and after propagation
  164.      * @since 11.1
  165.      */
  166.     protected AbstractMatricesHarvester createHarvester(final String stmName, final RealMatrix initialStm,
  167.                                                         final DoubleArrayDictionary initialJacobianColumns) {
  168.         // FIXME: not implemented as of 11.1
  169.         throw new UnsupportedOperationException();
  170.     }

  172.     /** Get the harvester.
  173.      * @return harvester, or null if it was not created
  174.      * @since 11.1
  175.      */
  176.     protected AbstractMatricesHarvester getHarvester() {
  177.         return harvester;
  178.     }

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

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

  191.         // update the states not managed by providers
  192.         for (final Map.Entry<String, TimeSpanMap<double[]>> entry : unmanagedStates.entrySet()) {
  193.             updated = updated.addAdditionalState(entry.getKey(),
  194.                                                  entry.getValue().get(original.getDate()));
  195.         }

  197.         return updated;

  199.     }

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

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

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

  216.         // update the additional states managed by providers, taking care of dependencies
  217.         int yieldCount = 0;
  218.         while (!pending.isEmpty()) {
  219.             final AdditionalStateProvider provider = pending.remove();
  220.             if (provider.yields(updated)) {
  221.                 // this generator has to wait for another one,
  222.                 // we put it again in the pending queue
  223.                 pending.add(provider);
  224.                 if (++yieldCount >= pending.size()) {
  225.                     // all pending providers yielded!, they probably need data not yet initialized
  226.                     // we let the propagation proceed, if these data are really needed right now
  227.                     // an appropriate exception will be triggered when caller tries to access them
  228.                     break;
  229.                 }
  230.             } else {
  231.                 // we can use this provider right now
  232.                 updated    = updated.addAdditionalState(provider.getName(), provider.getAdditionalState(updated));
  233.                 yieldCount = 0;
  234.             }
  235.         }

  237.         return updated;

  239.     }

  241.     /**
  242.      * Initialize the additional state providers at the start of propagation.
  243.      * @param target date of propagation. Not equal to {@code initialState.getDate()}.
  244.      * @since 11.2
  245.      */
  246.     protected void initializeAdditionalStates(final AbsoluteDate target) {
  247.         for (final AdditionalStateProvider provider : additionalStateProviders) {
  248.             provider.init(initialState, target);
  249.         }
  250.     }

  252.     /** {@inheritDoc} */
  253.     public boolean isAdditionalStateManaged(final String name) {
  254.         for (final AdditionalStateProvider provider : additionalStateProviders) {
  255.             if (provider.getName().equals(name)) {
  256.                 return true;
  257.             }
  258.         }
  259.         return false;
  260.     }

  262.     /** {@inheritDoc} */
  263.     public String[] getManagedAdditionalStates() {
  264.         final String[] managed = new String[additionalStateProviders.size()];
  265.         for (int i = 0; i < managed.length; ++i) {
  266.             managed[i] = additionalStateProviders.get(i).getName();
  267.         }
  268.         return managed;
  269.     }

  271.     /** {@inheritDoc} */
  272.     public SpacecraftState propagate(final AbsoluteDate target) {
  273.         if (startDate == null) {
  274.             startDate = getInitialState().getDate();
  275.         }
  276.         return propagate(startDate, target);
  277.     }

  279.     /** {@inheritDoc} */
  280.     public TimeStampedPVCoordinates getPVCoordinates(final AbsoluteDate date, final Frame frame) {
  281.         return propagate(date).getPVCoordinates(frame);
  282.     }

  284.     /** Initialize propagation.
  285.      * @since 10.1
  286.      */
  287.     protected void initializePropagation() {

  289.         unmanagedStates.clear();

  291.         if (initialState != null) {
  292.             // there is an initial state
  293.             // (null initial states occur for example in interpolated ephemerides)
  294.             // copy the additional states present in initialState but otherwise not managed
  295.             for (final DoubleArrayDictionary.Entry initial : initialState.getAdditionalStatesValues().getData()) {
  296.                 if (!isAdditionalStateManaged(initial.getKey())) {
  297.                     // this additional state is in the initial state, but is unknown to the propagator
  298.                     // we store it in a way event handlers may change it
  299.                     unmanagedStates.put(initial.getKey(), new TimeSpanMap<>(initial.getValue()));
  300.                 }
  301.             }
  302.         }
  303.     }

  305.     /** Notify about a state change.
  306.      * @param state new state
  307.      */
  308.     protected void stateChanged(final SpacecraftState state) {
  309.         final AbsoluteDate date    = state.getDate();
  310.         final boolean      forward = date.durationFrom(getStartDate()) >= 0.0;
  311.         for (final DoubleArrayDictionary.Entry changed : state.getAdditionalStatesValues().getData()) {
  312.             final TimeSpanMap<double[]> tsm = unmanagedStates.get(changed.getKey());
  313.             if (tsm != null) {
  314.                 // this is an unmanaged state
  315.                 if (forward) {
  316.                     tsm.addValidAfter(changed.getValue(), date, false);
  317.                 } else {
  318.                     tsm.addValidBefore(changed.getValue(), date, false);
  319.                 }
  320.             }
  321.         }
  322.     }

  324. }
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