AggregateBoundedPropagator.java
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* 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
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*/
package org.orekit.propagation.analytical;
import java.util.Collection;
import java.util.Map.Entry;
import java.util.NavigableMap;
import java.util.TreeMap;
import org.orekit.errors.OrekitException;
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.TimeStampedPVCoordinates;
/**
* A {@link BoundedPropagator} that covers a larger time span from several constituent
* propagators that cover shorter time spans.
*
* @author Evan Ward
* @see #AggregateBoundedPropagator(Collection)
*/
public class AggregateBoundedPropagator extends AbstractAnalyticalPropagator
implements BoundedPropagator {
/** Constituent propagators. */
private final NavigableMap<AbsoluteDate, BoundedPropagator> propagators;
/**
* Create a propagator by concatenating several {@link BoundedPropagator}s.
*
* @param propagators that provide the backing data for this instance. There must be
* at least one propagator in the collection. If there are gaps
* between the {@link BoundedPropagator#getMaxDate()} of one
* propagator and the {@link BoundedPropagator#getMinDate()} of the
* next propagator an exception may be thrown by any method of this
* class at any time. If there are overlaps between the the {@link
* BoundedPropagator#getMaxDate()} of one propagator and the {@link
* BoundedPropagator#getMinDate()} of the next propagator then the
* propagator with the latest {@link BoundedPropagator#getMinDate()}
* is used.
*/
public AggregateBoundedPropagator(
final Collection<? extends BoundedPropagator> propagators) {
super(DEFAULT_LAW);
if (propagators.isEmpty()) {
throw new OrekitException(OrekitMessages.NOT_ENOUGH_PROPAGATORS);
}
this.propagators = new TreeMap<>();
for (final BoundedPropagator propagator : propagators) {
this.propagators.put(propagator.getMinDate(), propagator);
}
super.resetInitialState(
this.propagators.firstEntry().getValue().getInitialState());
}
@Override
public TimeStampedPVCoordinates getPVCoordinates(final AbsoluteDate date,
final Frame frame) {
return getPropagator(date).getPVCoordinates(date, frame);
}
@Override
protected Orbit propagateOrbit(final AbsoluteDate date) {
return getPropagator(date).propagate(date).getOrbit();
}
@Override
public AbsoluteDate getMinDate() {
return propagators.firstEntry().getValue().getMinDate();
}
@Override
public AbsoluteDate getMaxDate() {
return propagators.lastEntry().getValue().getMaxDate();
}
@Override
protected double getMass(final AbsoluteDate date) {
return getPropagator(date).propagate(date).getMass();
}
@Override
public SpacecraftState getInitialState() {
return propagators.firstEntry().getValue().getInitialState();
}
@Override
protected void resetIntermediateState(final SpacecraftState state,
final boolean forward) {
throw new OrekitException(OrekitMessages.NON_RESETABLE_STATE);
}
@Override
public void resetInitialState(final SpacecraftState state) {
throw new OrekitException(OrekitMessages.NON_RESETABLE_STATE);
}
/**
* Get the propagator to use for the given date.
*
* @param date of query
* @return propagator to use on date.
*/
private BoundedPropagator getPropagator(final AbsoluteDate date) {
final Entry<AbsoluteDate, BoundedPropagator> entry = propagators.floorEntry(date);
if (entry != null) {
return entry.getValue();
} else {
// let the first propagator throw the exception
return propagators.firstEntry().getValue();
}
}
}