FieldAbstractPropagator.java
/* Copyright 2002-2021 CS GROUP
* Licensed to CS GROUP (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;
import java.util.ArrayList;
import java.util.Collections;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import org.hipparchus.CalculusFieldElement;
import org.hipparchus.Field;
import org.orekit.attitudes.AttitudeProvider;
import org.orekit.errors.OrekitException;
import org.orekit.errors.OrekitMessages;
import org.orekit.frames.Frame;
import org.orekit.propagation.sampling.FieldStepHandlerMultiplexer;
import org.orekit.time.AbsoluteDate;
import org.orekit.time.FieldAbsoluteDate;
import org.orekit.utils.TimeSpanMap;
import org.orekit.utils.TimeStampedFieldPVCoordinates;
/** Common handling of {@link Propagator} methods for analytical propagators.
* <p>
* This abstract class allows to provide easily the full set of {@link Propagator}
* methods, including all propagation modes support and discrete events support for
* any simple propagation method.
* </p>
* @param <T> the type of the field elements
* @author Luc Maisonobe
*/
public abstract class FieldAbstractPropagator<T extends CalculusFieldElement<T>> implements FieldPropagator<T> {
/** Multiplexer for step handlers. */
private FieldStepHandlerMultiplexer<T> multiplexer;
/** Start date. */
private FieldAbsoluteDate<T> startDate;
/** Attitude provider. */
private AttitudeProvider attitudeProvider;
/** Additional state providers. */
private final List<FieldAdditionalStateProvider<T>> additionalStateProviders;
/** States managed by neither additional equations nor state providers. */
private final Map<String, TimeSpanMap<T[]>> unmanagedStates;
/** Field used.*/
private final Field<T> field;
/** Initial state. */
private FieldSpacecraftState<T> initialState;
/** Build a new instance.
* @param field setting the field
*/
protected FieldAbstractPropagator(final Field<T> field) {
this.field = field;
multiplexer = new FieldStepHandlerMultiplexer<>();
additionalStateProviders = new ArrayList<>();
unmanagedStates = new HashMap<>();
}
/** Set a start date.
* @param startDate start date
*/
protected void setStartDate(final FieldAbsoluteDate<T> startDate) {
this.startDate = startDate;
}
/** Get the start date.
* @return start date
*/
protected FieldAbsoluteDate<T> getStartDate() {
return startDate;
}
/** {@inheritDoc} */
public AttitudeProvider getAttitudeProvider() {
return attitudeProvider;
}
/** {@inheritDoc} */
public void setAttitudeProvider(final AttitudeProvider attitudeProvider) {
this.attitudeProvider = attitudeProvider;
}
/** Field getter.
* @return field used*/
public Field<T> getField() {
return field;
}
/** {@inheritDoc} */
public FieldSpacecraftState<T> getInitialState() {
return initialState;
}
/** {@inheritDoc} */
public Frame getFrame() {
return initialState.getFrame();
}
/** {@inheritDoc} */
public void resetInitialState(final FieldSpacecraftState<T> state) {
initialState = state;
setStartDate(state.getDate());
}
/** {@inheritDoc} */
public FieldStepHandlerMultiplexer<T> getMultiplexer() {
return multiplexer;
}
/** {@inheritDoc} */
public void addAdditionalStateProvider(final FieldAdditionalStateProvider<T> additionalStateProvider) {
// check if the name is already used
if (isAdditionalStateManaged(additionalStateProvider.getName())) {
// this additional state is already registered, complain
throw new OrekitException(OrekitMessages.ADDITIONAL_STATE_NAME_ALREADY_IN_USE,
additionalStateProvider.getName());
}
// this is really a new name, add it
additionalStateProviders.add(additionalStateProvider);
}
/** {@inheritDoc} */
public List<FieldAdditionalStateProvider<T>> getAdditionalStateProviders() {
return Collections.unmodifiableList(additionalStateProviders);
}
/** Update state by adding all additional states.
* @param original original state
* @return updated state, with all additional states included
* @see #addAdditionalStateProvider(FieldAdditionalStateProvider)
*/
protected FieldSpacecraftState<T> updateAdditionalStates(final FieldSpacecraftState<T> original) {
// start with original state,
// which may already contain additional states, for example in interpolated ephemerides
FieldSpacecraftState<T> updated = original;
// update the states not managed by providers
for (final Map.Entry<String, TimeSpanMap<T[]>> entry : unmanagedStates.entrySet()) {
updated = updated.addAdditionalState(entry.getKey(),
entry.getValue().get(original.getDate().toAbsoluteDate()));
}
// update the additional states managed by providers
for (final FieldAdditionalStateProvider<T> provider : additionalStateProviders) {
updated = updated.addAdditionalState(provider.getName(),
provider.getAdditionalState(updated));
}
return updated;
}
/** {@inheritDoc} */
public boolean isAdditionalStateManaged(final String name) {
for (final FieldAdditionalStateProvider<T> provider : additionalStateProviders) {
if (provider.getName().equals(name)) {
return true;
}
}
return false;
}
/** {@inheritDoc} */
public String[] getManagedAdditionalStates() {
final String[] managed = new String[additionalStateProviders.size()];
for (int i = 0; i < managed.length; ++i) {
managed[i] = additionalStateProviders.get(i).getName();
}
return managed;
}
/** {@inheritDoc} */
public FieldSpacecraftState<T> propagate(final FieldAbsoluteDate<T> target) {
if (startDate == null) {
startDate = getInitialState().getDate();
}
return propagate(startDate, target);
}
/** {@inheritDoc} */
public TimeStampedFieldPVCoordinates<T> getPVCoordinates(final FieldAbsoluteDate<T> date, final Frame frame) {
return propagate(date).getPVCoordinates(frame);
}
/** Initialize propagation.
* @since 10.1
*/
protected void initializePropagation() {
unmanagedStates.clear();
if (initialState != null) {
// there is an initial state
// (null initial states occur for example in interpolated ephemerides)
// copy the additional states present in initialState but otherwise not managed
for (final Map.Entry<String, T[]> initial : initialState.getAdditionalStates().entrySet()) {
if (!isAdditionalStateManaged(initial.getKey())) {
// this additional state is in the initial state, but is unknown to the propagator
// we store it in a way event handlers may change it
unmanagedStates.put(initial.getKey(), new TimeSpanMap<>(initial.getValue()));
}
}
}
}
/** Notify about a state change.
* @param state new state
*/
protected void stateChanged(final FieldSpacecraftState<T> state) {
final AbsoluteDate date = state.getDate().toAbsoluteDate();
final boolean forward = date.durationFrom(getStartDate().toAbsoluteDate()) >= 0.0;
for (final Map.Entry<String, T[]> changed : state.getAdditionalStates().entrySet()) {
final TimeSpanMap<T[]> tsm = unmanagedStates.get(changed.getKey());
if (tsm != null) {
// this is an unmanaged state
if (forward) {
tsm.addValidAfter(changed.getValue(), date);
} else {
tsm.addValidBefore(changed.getValue(), date);
}
}
}
}
}