Propagator.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.Collection;
  20. import java.util.List;

  22. import org.hipparchus.geometry.euclidean.threed.Rotation;
  23. import org.hipparchus.linear.RealMatrix;
  24. import org.orekit.attitudes.AttitudeProvider;
  25. import org.orekit.attitudes.FrameAlignedProvider;
  26. import org.orekit.frames.Frame;
  27. import org.orekit.frames.Frames;
  28. import org.orekit.orbits.PositionAngleType;
  29. import org.orekit.propagation.events.EventDetector;
  30. import org.orekit.propagation.sampling.OrekitFixedStepHandler;
  31. import org.orekit.propagation.sampling.OrekitStepHandler;
  32. import org.orekit.propagation.sampling.StepHandlerMultiplexer;
  33. import org.orekit.time.AbsoluteDate;
  34. import org.orekit.utils.DoubleArrayDictionary;
  35. import org.orekit.utils.PVCoordinatesProvider;

  37. /** This interface provides a way to propagate an orbit at any time.
  38.  *
  39.  * <p>This interface is the top-level abstraction for orbit propagation.
  40.  * It only allows propagation to a predefined date.
  41.  * It is implemented by analytical models which have no time limit,
  42.  * by orbit readers based on external data files, by numerical integrators
  43.  * using rich force models and by continuous models built after numerical
  44.  * integration has been completed and dense output data as been
  45.  * gathered.</p>
  46.  * <p>Note that one single propagator cannot be called from multiple threads.
  47.  * Its configuration can be changed as there is at least a {@link
  48.  * #resetInitialState(SpacecraftState)} method, and even propagators that do
  49.  * not support resetting state (like the {@link
  50.  * org.orekit.propagation.analytical.tle.TLEPropagator TLEPropagator} do
  51.  * cache some internal data during computation. However, as long as they
  52.  * are configured with independent building blocks (mainly event handlers
  53.  * and step handlers that may preserve some internal state), and as long
  54.  * as they are called from one thread only, they <em>can</em> be used in
  55.  * multi-threaded applications. Synchronizing several propagators to run in
  56.  * parallel is also possible using {@link PropagatorsParallelizer}.</p>
  57.  * @author Luc Maisonobe
  58.  * @author V&eacute;ronique Pommier-Maurussane
  59.  *
  60.  */

  62. public interface Propagator extends PVCoordinatesProvider {

  64.     /** Default mass. */
  65.     double DEFAULT_MASS = 1000.0;

  67.     /**
  68.      * Get a default law using the given frames.
  69.      *
  70.      * @param frames the set of frames to use.
  71.      * @return attitude law.
  72.      */
  73.     static AttitudeProvider getDefaultLaw(final Frames frames) {
  74.         return new FrameAlignedProvider(Rotation.IDENTITY, frames.getEME2000());
  75.     }

  77.     /** Get the multiplexer holding all step handlers.
  78.      * @return multiplexer holding all step handlers
  79.      * @since 11.0
  80.      */
  81.     StepHandlerMultiplexer getMultiplexer();

  83.     /** Remove all step handlers.
  84.      * <p>This convenience method is equivalent to call {@code getMultiplexer().clear()}</p>
  85.      * @see #getMultiplexer()
  86.      * @see StepHandlerMultiplexer#clear()
  87.      * @since 11.0
  88.      */
  89.     default void clearStepHandlers() {
  90.         getMultiplexer().clear();
  91.     }

  93.     /** Set a single handler for fixed stepsizes.
  94.      * <p>This convenience method is equivalent to call {@code getMultiplexer().clear()}
  95.      * followed by {@code getMultiplexer().add(h, handler)}</p>
  96.      * @param h fixed stepsize (s)
  97.      * @param handler handler called at the end of each finalized step
  98.      * @see #getMultiplexer()
  99.      * @see StepHandlerMultiplexer#add(double, OrekitFixedStepHandler)
  100.      * @since 11.0
  101.      */
  102.     default void setStepHandler(final double h, final OrekitFixedStepHandler handler) {
  103.         getMultiplexer().clear();
  104.         getMultiplexer().add(h, handler);
  105.     }

  107.     /** Set a single handler for variable stepsizes.
  108.      * <p>This convenience method is equivalent to call {@code getMultiplexer().clear()}
  109.      * followed by {@code getMultiplexer().add(handler)}</p>
  110.      * @param handler handler called at the end of each finalized step
  111.      * @see #getMultiplexer()
  112.      * @see StepHandlerMultiplexer#add(OrekitStepHandler)
  113.      * @since 11.0
  114.      */
  115.     default void setStepHandler(final OrekitStepHandler handler) {
  116.         getMultiplexer().clear();
  117.         getMultiplexer().add(handler);
  118.     }

  120.     /**
  121.      * Set up an ephemeris generator that will monitor the propagation for building
  122.      * an ephemeris from it once completed.
  123.      *
  124.      * <p>
  125.      * This generator can be used when the user needs fast random access to the orbit
  126.      * state at any time between the initial and target times. A typical example is the
  127.      * implementation of search and iterative algorithms that may navigate forward and
  128.      * backward inside the propagation range before finding their result even if the
  129.      * propagator used is integration-based and only goes from one initial time to one
  130.      * target time.
  131.      * </p>
  132.      * <p>
  133.      * Beware that when used with integration-based propagators, the generator will
  134.      * store <strong>all</strong> intermediate results. It is therefore memory intensive
  135.      * for long integration-based ranges and high precision/short time steps. When
  136.      * used with analytical propagators, the generator only stores start/stop time
  137.      * and a reference to the analytical propagator itself to call it back as needed,
  138.      * so it is less memory intensive.
  139.      * </p>
  140.      * <p>
  141.      * The returned ephemeris generator will be initially empty, it will be filled
  142.      * with propagation data when a subsequent call to either {@link #propagate(AbsoluteDate)
  143.      * propagate(target)} or {@link #propagate(AbsoluteDate, AbsoluteDate)
  144.      * propagate(start, target)} is called. The proper way to use this method is
  145.      * therefore to do:
  146.      * </p>
  147.      * <pre>
  148.      *   EphemerisGenerator generator = propagator.getEphemerisGenerator();
  149.      *   propagator.propagate(target);
  150.      *   BoundedPropagator ephemeris = generator.getGeneratedEphemeris();
  151.      * </pre>
  152.      * @return ephemeris generator
  153.      */
  154.     EphemerisGenerator getEphemerisGenerator();

  156.     /** Get the propagator initial state.
  157.      * @return initial state
  158.      */
  159.     SpacecraftState getInitialState();

  161.     /** Reset the propagator initial state.
  162.      * @param state new initial state to consider
  163.      */
  164.     void resetInitialState(SpacecraftState state);

  166.     /** Add a set of user-specified state parameters to be computed along with the orbit propagation.
  167.      * @param additionalStateProvider provider for additional state
  168.      */
  169.     void addAdditionalStateProvider(AdditionalStateProvider additionalStateProvider);

  171.     /** Get an unmodifiable list of providers for additional state.
  172.      * @return providers for the additional states
  173.      */
  174.     List<AdditionalStateProvider> getAdditionalStateProviders();

  176.     /** Check if an additional state is managed.
  177.      * <p>
  178.      * Managed states are states for which the propagators know how to compute
  179.      * its evolution. They correspond to additional states for which a
  180.      * {@link AdditionalStateProvider provider} has been registered by calling the
  181.      * {@link #addAdditionalStateProvider(AdditionalStateProvider) addAdditionalStateProvider} method.
  182.      * </p>
  183.      * <p>
  184.      * Additional states that are present in the {@link #getInitialState() initial state}
  185.      * but have no evolution method registered are <em>not</em> considered as managed states.
  186.      * These unmanaged additional states are not lost during propagation, though. Their
  187.      * value are piecewise constant between state resets that may change them if some
  188.      * event handler {@link
  189.      * org.orekit.propagation.events.handlers.EventHandler#resetState(EventDetector,
  190.      * SpacecraftState) resetState} method is called at an event occurrence and happens
  191.      * to change the unmanaged additional state.
  192.      * </p>
  193.      * @param name name of the additional state
  194.      * @return true if the additional state is managed
  195.      */
  196.     boolean isAdditionalStateManaged(String name);

  198.     /** Get all the names of all managed states.
  199.      * @return names of all managed states
  200.      */
  201.     String[] getManagedAdditionalStates();

  203.     /** Add an event detector.
  204.      * @param detector event detector to add
  205.      * @see #clearEventsDetectors()
  206.      * @see #getEventsDetectors()
  207.      * @param <T> class type for the generic version
  208.      */
  209.     <T extends EventDetector> void addEventDetector(T detector);

  211.     /** Get all the events detectors that have been added.
  212.      * @return an unmodifiable collection of the added detectors
  213.      * @see #addEventDetector(EventDetector)
  214.      * @see #clearEventsDetectors()
  215.      */
  216.     Collection<EventDetector> getEventsDetectors();

  218.     /** Remove all events detectors.
  219.      * @see #addEventDetector(EventDetector)
  220.      * @see #getEventsDetectors()
  221.      */
  222.     void clearEventsDetectors();

  224.     /** Get attitude provider.
  225.      * @return attitude provider
  226.      */
  227.     AttitudeProvider getAttitudeProvider();

  229.     /** Set attitude provider.
  230.      * @param attitudeProvider attitude provider
  231.      */
  232.     void setAttitudeProvider(AttitudeProvider attitudeProvider);

  234.     /** Get the frame in which the orbit is propagated.
  235.      * <p>
  236.      * The propagation frame is the definition frame of the initial
  237.      * state, so this method should be called after this state has
  238.      * been set, otherwise it may return null.
  239.      * </p>
  240.      * @return frame in which the orbit is propagated
  241.      * @see #resetInitialState(SpacecraftState)
  242.      */
  243.     Frame getFrame();

  245.     /** Set up computation of State Transition Matrix and Jacobians matrix with respect to parameters.
  246.      * <p>
  247.      * If this method is called, both State Transition Matrix and Jacobians with respect to the
  248.      * force models parameters that will be selected when propagation starts will be automatically
  249.      * computed, and the harvester will allow to retrieve them.
  250.      * </p>
  251.      * <p>
  252.      * The arguments for initial matrices <em>must</em> be compatible with the {@link org.orekit.orbits.OrbitType
  253.      * orbit type} and {@link PositionAngleType position angle} that will be used by the propagator.
  254.      * </p>
  255.      * <p>
  256.      * The default implementation throws an exception as the method is not supported by all propagators.
  257.      * </p>
  258.      * @param stmName State Transition Matrix state name
  259.      * @param initialStm initial State Transition Matrix ∂Y/∂Y₀,
  260.      * if null (which is the most frequent case), assumed to be 6x6 identity
  261.      * @param initialJacobianColumns initial columns of the Jacobians matrix with respect to parameters,
  262.      * if null or if some selected parameters are missing from the dictionary, the corresponding
  263.      * initial column is assumed to be 0
  264.      * @return harvester to retrieve computed matrices during and after propagation
  265.      * @since 11.1
  266.      */
  267.     default MatricesHarvester setupMatricesComputation(final String stmName, final RealMatrix initialStm,
  268.                                                        final DoubleArrayDictionary initialJacobianColumns) {
  269.         throw new UnsupportedOperationException();
  270.     }

  272.     /** Propagate towards a target date.
  273.      * <p>Simple propagators use only the target date as the specification for
  274.      * computing the propagated state. More feature rich propagators can consider
  275.      * other information and provide different operating modes or G-stop
  276.      * facilities to stop at pinpointed events occurrences. In these cases, the
  277.      * target date is only a hint, not a mandatory objective.</p>
  278.      * @param target target date towards which orbit state should be propagated
  279.      * @return propagated state
  280.      */
  281.     SpacecraftState propagate(AbsoluteDate target);

  283.     /** Propagate from a start date towards a target date.
  284.      * <p>Those propagators use a start date and a target date to
  285.      * compute the propagated state. For propagators using event detection mechanism,
  286.      * if the provided start date is different from the initial state date, a first,
  287.      * simple propagation is performed, without processing any event computation.
  288.      * Then complete propagation is performed from start date to target date.</p>
  289.      * @param start start date from which orbit state should be propagated
  290.      * @param target target date to which orbit state should be propagated
  291.      * @return propagated state
  292.      */
  293.     SpacecraftState propagate(AbsoluteDate start, AbsoluteDate target);

  295. }
Created with JaCoCo 0.8.11.202310140853