Ephemeris.java
- /* Copyright 2002-2016 CS Systèmes d'Information
- * Licensed to CS Systèmes d'Information (CS) under one or more
- * contributor license agreements. See the NOTICE file distributed with
- * this work for additional information regarding copyright ownership.
- * CS licenses this file to You under the Apache License, Version 2.0
- * (the "License"); you may not use this file except in compliance with
- * the License. You may obtain a copy of the License at
- *
- * http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
- package org.orekit.propagation.analytical;
- import java.io.Serializable;
- import java.util.List;
- import java.util.Set;
- import org.hipparchus.exception.LocalizedCoreFormats;
- import org.hipparchus.exception.MathIllegalArgumentException;
- import org.hipparchus.util.FastMath;
- import org.orekit.attitudes.Attitude;
- import org.orekit.attitudes.AttitudeProvider;
- import org.orekit.errors.OrekitException;
- import org.orekit.errors.OrekitInternalError;
- import org.orekit.errors.OrekitMessages;
- import org.orekit.frames.Frame;
- import org.orekit.orbits.Orbit;
- import org.orekit.propagation.BoundedPropagator;
- import org.orekit.propagation.SpacecraftState;
- import org.orekit.time.AbsoluteDate;
- import org.orekit.utils.ImmutableTimeStampedCache;
- import org.orekit.utils.PVCoordinatesProvider;
- import org.orekit.utils.TimeStampedPVCoordinates;
- /** This class is designed to accept and handle tabulated orbital entries.
- * Tabulated entries are classified and then extrapolated in way to obtain
- * continuous output, with accuracy and computation methods configured by the user.
- *
- * @author Fabien Maussion
- * @author Véronique Pommier-Maurussane
- * @author Luc Maisonobe
- */
- public class Ephemeris extends AbstractAnalyticalPropagator implements BoundedPropagator, Serializable {
- /** Serializable UID. */
- private static final long serialVersionUID = 20151022L;
- /** First date in range. */
- private final AbsoluteDate minDate;
- /** Last date in range. */
- private final AbsoluteDate maxDate;
- /** Reference frame. */
- private final Frame frame;
- /** Names of the additional states. */
- private final String[] additional;
- /** Local PV Provider used for computing attitude. **/
- private LocalPVProvider pvProvider;
- /** Thread-safe cache. */
- private final transient ImmutableTimeStampedCache<SpacecraftState> cache;
- /** Constructor with tabulated states.
- * @param states tabulates states
- * @param interpolationPoints number of points to use in interpolation
- * @exception OrekitException if some states have incompatible additional states
- * @exception MathIllegalArgumentException if the number of states is smaller than
- * the number of points to use in interpolation
- */
- public Ephemeris(final List<SpacecraftState> states, final int interpolationPoints)
- throws OrekitException, MathIllegalArgumentException {
- super(DEFAULT_LAW);
- if (states.size() < interpolationPoints) {
- throw new MathIllegalArgumentException(LocalizedCoreFormats.INSUFFICIENT_DIMENSION,
- states.size(), interpolationPoints);
- }
- final SpacecraftState s0 = states.get(0);
- minDate = s0.getDate();
- maxDate = states.get(states.size() - 1).getDate();
- frame = s0.getFrame();
- final Set<String> names0 = s0.getAdditionalStates().keySet();
- additional = names0.toArray(new String[names0.size()]);
- // check all states handle the same additional states
- for (final SpacecraftState state : states) {
- s0.ensureCompatibleAdditionalStates(state);
- }
- pvProvider = new LocalPVProvider();
- //User needs to explicitly set attitude provider if they want to use one
- this.setAttitudeProvider(null);
- // set up cache
- cache = new ImmutableTimeStampedCache<SpacecraftState>(interpolationPoints, states);
- }
- /** Get the first date of the range.
- * @return the first date of the range
- */
- public AbsoluteDate getMinDate() {
- return minDate;
- }
- /** Get the last date of the range.
- * @return the last date of the range
- */
- public AbsoluteDate getMaxDate() {
- return maxDate;
- }
- @Override
- public Frame getFrame() {
- return this.frame;
- }
- @Override
- /** {@inheritDoc} */
- public SpacecraftState basicPropagate(final AbsoluteDate date) throws OrekitException {
- final List<SpacecraftState> neighbors = cache.getNeighbors(date);
- final SpacecraftState interpolatedState = neighbors.get(0).interpolate(date, neighbors);
- final AttitudeProvider attitudeProvider = this.getAttitudeProvider();
- if (attitudeProvider == null) {
- return interpolatedState;
- }
- else {
- pvProvider.setCurrentState(interpolatedState);
- final Attitude calculatedAttitude = attitudeProvider.getAttitude(pvProvider, date, interpolatedState.getFrame());
- return new SpacecraftState(interpolatedState.getOrbit(), calculatedAttitude, interpolatedState.getMass());
- }
- }
- /** {@inheritDoc} */
- protected Orbit propagateOrbit(final AbsoluteDate date) throws OrekitException {
- return basicPropagate(date).getOrbit();
- }
- /** {@inheritDoc} */
- protected double getMass(final AbsoluteDate date) throws OrekitException {
- return basicPropagate(date).getMass();
- }
- /** {@inheritDoc} */
- public TimeStampedPVCoordinates getPVCoordinates(final AbsoluteDate date, final Frame f)
- throws OrekitException {
- return propagate(date).getPVCoordinates(f);
- }
- /** Try (and fail) to reset the initial state.
- * <p>
- * This method always throws an exception, as ephemerides cannot be reset.
- * </p>
- * @param state new initial state to consider
- * @exception OrekitException always thrown as ephemerides cannot be reset
- */
- public void resetInitialState(final SpacecraftState state)
- throws OrekitException {
- throw new OrekitException(OrekitMessages.NON_RESETABLE_STATE);
- }
- /** {@inheritDoc} */
- protected void resetIntermediateState(final SpacecraftState state, final boolean forward)
- throws OrekitException {
- throw new OrekitException(OrekitMessages.NON_RESETABLE_STATE);
- }
- /** {@inheritDoc} */
- public SpacecraftState getInitialState() throws OrekitException {
- return basicPropagate(getMinDate());
- }
- /** {@inheritDoc} */
- @Override
- public boolean isAdditionalStateManaged(final String name) {
- // the additional state may be managed by a specific provider in the base class
- if (super.isAdditionalStateManaged(name)) {
- return true;
- }
- // the additional state may be managed in the states sample
- for (final String a : additional) {
- if (a.equals(name)) {
- return true;
- }
- }
- return false;
- }
- /** {@inheritDoc} */
- @Override
- public String[] getManagedAdditionalStates() {
- final String[] upperManaged = super.getManagedAdditionalStates();
- final String[] managed = new String[upperManaged.length + additional.length];
- System.arraycopy(upperManaged, 0, managed, 0, upperManaged.length);
- System.arraycopy(additional, 0, managed, upperManaged.length, additional.length);
- return managed;
- }
- /** Replace the instance with a data transfer object for serialization.
- * <p>
- * This intermediate class serializes only the data needed for generation,
- * but does <em>not</em> serializes the cache itself (in fact the cache is
- * not serializable).
- * </p>
- * @return data transfer object that will be serialized
- */
- private Object writeReplace() {
- return new DataTransferObject(cache.getAll(), cache.getNeighborsSize());
- }
- /** Internal class used only for serialization. */
- private static class DataTransferObject implements Serializable {
- /** Serializable UID. */
- private static final long serialVersionUID = -8479036196711159270L;
- /** Tabulates states. */
- private final List<SpacecraftState> states;
- /** Number of points to use in interpolation. */
- private final int interpolationPoints;
- /** Simple constructor.
- * @param states tabulates states
- * @param interpolationPoints number of points to use in interpolation
- */
- private DataTransferObject(final List<SpacecraftState> states, final int interpolationPoints) {
- this.states = states;
- this.interpolationPoints = interpolationPoints;
- }
- /** Replace the deserialized data transfer object with a {@link Ephemeris}.
- * @return replacement {@link Ephemeris}
- */
- private Object readResolve() {
- try {
- // build a new provider, with an empty cache
- return new Ephemeris(states, interpolationPoints);
- } catch (OrekitException oe) {
- // this should never happen
- throw new OrekitInternalError(oe);
- }
- }
- }
- /** Internal PVCoordinatesProvider for attitude computation. */
- private static class LocalPVProvider implements PVCoordinatesProvider, Serializable {
- /** Serializable UID. */
- private static final long serialVersionUID = 20160115L;
- /** Current state. */
- private SpacecraftState currentState;
- /** Get the current state.
- * @return current state
- */
- public SpacecraftState getCurrentState() {
- return currentState;
- }
- /** Set the current state.
- * @param state state to set
- */
- public void setCurrentState(final SpacecraftState state) {
- this.currentState = state;
- }
- /** {@inheritDoc} */
- public TimeStampedPVCoordinates getPVCoordinates(final AbsoluteDate date, final Frame f)
- throws OrekitException {
- final double dt = this.getCurrentState().getDate().durationFrom(date);
- final double closeEnoughTimeInSec = 1e-9;
- if (FastMath.abs(dt) > closeEnoughTimeInSec) {
- throw new OrekitException(LocalizedCoreFormats.OUT_OF_RANGE_SIMPLE,
- FastMath.abs(dt), 0.0, closeEnoughTimeInSec);
- }
- return this.getCurrentState().getPVCoordinates(f);
- }
- }
- }