FieldAbstractPropagator.java
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* CS licenses this file to You under the Apache License, Version 2.0
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* http://www.apache.org/licenses/LICENSE-2.0
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* Unless required by applicable law or agreed to in writing, software
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package org.orekit.propagation;
import java.util.ArrayList;
import java.util.Collections;
import java.util.HashMap;
import java.util.LinkedList;
import java.util.List;
import java.util.Map;
import java.util.Queue;
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.FieldAbsoluteDate;
import org.orekit.utils.FieldArrayDictionary;
import org.orekit.utils.FieldTimeSpanMap;
/** 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 final 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, FieldTimeSpanMap<T[], 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 unmanaged states.
* @param original original state
* @return updated state, with unmanaged states included
* @see #updateAdditionalStates(FieldSpacecraftState)
*/
protected FieldSpacecraftState<T> updateUnmanagedStates(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, FieldTimeSpanMap<T[], T>> entry : unmanagedStates.entrySet()) {
updated = updated.addAdditionalState(entry.getKey(),
entry.getValue().get(original.getDate()));
}
return updated;
}
/** 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 and unmanaged states
FieldSpacecraftState<T> updated = updateUnmanagedStates(original);
// set up queue for providers
final Queue<FieldAdditionalStateProvider<T>> pending = new LinkedList<>(getAdditionalStateProviders());
// update the additional states managed by providers, taking care of dependencies
int yieldCount = 0;
while (!pending.isEmpty()) {
final FieldAdditionalStateProvider<T> provider = pending.remove();
if (provider.yields(updated)) {
// this generator has to wait for another one,
// we put it again in the pending queue
pending.add(provider);
if (++yieldCount >= pending.size()) {
// all pending providers yielded!, they probably need data not yet initialized
// we let the propagation proceed, if these data are really needed right now
// an appropriate exception will be triggered when caller tries to access them
break;
}
} else {
// we can use this provider right now
updated = provider.update(updated);
yieldCount = 0;
}
}
return updated;
}
/**
* Initialize the additional state providers at the start of propagation.
* @param target date of propagation. Not equal to {@code initialState.getDate()}.
* @since 11.2
*/
protected void initializeAdditionalStates(final FieldAbsoluteDate<T> target) {
for (final FieldAdditionalStateProvider<T> provider : additionalStateProviders) {
provider.init(initialState, target);
}
}
/** {@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);
}
/** 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 FieldArrayDictionary<T>.Entry initial : initialState.getAdditionalStatesValues().getData()) {
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 FieldTimeSpanMap<>(initial.getValue(),
initialState.getDate().getField()));
}
}
}
}
/** Notify about a state change.
* @param state new state
*/
protected void stateChanged(final FieldSpacecraftState<T> state) {
final FieldAbsoluteDate<T> date = state.getDate();
final boolean forward = date.durationFrom(getStartDate()).getReal() >= 0.0;
for (final FieldArrayDictionary<T>.Entry changed : state.getAdditionalStatesValues().getData()) {
final FieldTimeSpanMap<T[], 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);
}
}
}
}
}