JacobianPropagatorConverter.java
/* Copyright 2002-2026 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.conversion;
import java.util.List;
import org.hipparchus.analysis.MultivariateVectorFunction;
import org.hipparchus.geometry.euclidean.threed.Vector3D;
import org.hipparchus.linear.ArrayRealVector;
import org.hipparchus.linear.MatrixUtils;
import org.hipparchus.linear.RealMatrix;
import org.hipparchus.linear.RealVector;
import org.hipparchus.optim.nonlinear.vector.leastsquares.MultivariateJacobianFunction;
import org.hipparchus.util.Pair;
import org.orekit.errors.OrekitException;
import org.orekit.errors.OrekitMessages;
import org.orekit.orbits.OrbitParamsType;
import org.orekit.orbits.OrbitalStateFactory;
import org.orekit.propagation.MatricesHarvester;
import org.orekit.propagation.Propagator;
import org.orekit.propagation.SpacecraftState;
import org.orekit.propagation.sampling.OrekitStepHandler;
import org.orekit.propagation.sampling.OrekitStepInterpolator;
import org.orekit.time.AbsoluteDate;
import org.orekit.utils.PVCoordinates;
import org.orekit.utils.drivers.ParameterDriver;
import org.orekit.utils.drivers.ParameterDriversList;
/** Propagator converter using the real Jacobian.
* @author Pascal Parraud
* @since 6.0
*/
public class JacobianPropagatorConverter extends AbstractPropagatorConverter {
/** Time step. */
private static final double DT = 10.;
/** Propagator builder. */
private final PropagatorBuilder builder;
/** Simple constructor.
* @param builder builder for adapted propagator, it <em>must</em>
* be configured to generate {@link OrbitParamsType#CARTESIAN} states
* @param threshold absolute threshold for optimization algorithm
* @param maxIterations maximum number of iterations for fitting
*/
public JacobianPropagatorConverter(final PropagatorBuilder builder,
final double threshold,
final int maxIterations) {
super(builder, threshold, maxIterations);
final OrbitalStateFactory<?> factory = builder.getOrbitalStateFactory();
if (factory.getOrbitParamsType() != OrbitParamsType.CARTESIAN) {
throw new OrekitException(OrekitMessages.ORBIT_TYPE_NOT_ALLOWED,
factory.getOrbitParamsType(), OrbitParamsType.CARTESIAN);
}
this.builder = builder;
}
/** {@inheritDoc} */
protected MultivariateVectorFunction getObjectiveFunction() {
return point -> {
final Propagator propagator = builder.buildPropagator(point);
final ValuesHandler handler = new ValuesHandler();
propagator.getMultiplexer().add(handler);
final List<SpacecraftState> sample = getSample();
propagator.propagate(sample.getLast().getDate().shiftedBy(DT));
return handler.value.toArray();
};
}
/** {@inheritDoc} */
protected MultivariateJacobianFunction getModel() {
return point -> {
final Propagator propagator = builder.buildPropagator(point.toArray());
final JacobianHandler handler = new JacobianHandler(propagator, point.getDimension());
propagator.getMultiplexer().add(handler);
final List<SpacecraftState> sample = getSample();
propagator.propagate(sample.getLast().getDate().shiftedBy(DT));
return new Pair<>(handler.getValue(), handler.jacobian);
};
}
/** Handler for picking up values at sample dates.
* <p>
* This class is heavily based on org.orekit.estimation.leastsquares.MeasurementHandler.
* </p>
* @since 11.1
*/
private class ValuesHandler implements OrekitStepHandler {
/** Values vector. */
private final RealVector value;
/** State size (3 or 6). */
private final int stateSize;
/** Number of the next measurement. */
private int number;
/** Index of the next component in the model. */
private int index;
/** Simple constructor.
*/
ValuesHandler() {
this.value = new ArrayRealVector(getTargetSize());
this.stateSize = isOnlyPosition() ? 3 : 6;
}
/**
* Getter for value.
* @return value
* @since 14.0
*/
RealVector getValue() {
return value;
}
/**
* Getter for index.
* @return index
* @since 14.0
*/
int getIndex() {
return index;
}
/**
* Getter for state size.
* @return size
* @since 14.0
*/
int getStateSize() {
return stateSize;
}
/** {@inheritDoc} */
@Override
public void init(final SpacecraftState initialState, final AbsoluteDate target) {
number = 0;
index = 0;
}
/** {@inheritDoc} */
@Override
public void handleStep(final OrekitStepInterpolator interpolator) {
while (number < getSample().size()) {
// Consider the next sample to handle
final SpacecraftState next = getSample().get(number);
// Current state date
final AbsoluteDate currentDate = interpolator.getCurrentState().getDate();
if (next.getDate().compareTo(currentDate) > 0) {
return;
}
fillRows(interpolator.getInterpolatedState(next.getDate()));
// prepare handling of next measurement
index += stateSize;
++number;
}
}
/**
* Fill vector.
* @param state state
*/
protected void fillRows(final SpacecraftState state) {
final PVCoordinates pv = state.getPVCoordinates(getFrame());
final Vector3D position = pv.getPosition();
value.setEntry(index, position.getX());
value.setEntry(index + 1, position.getY());
value.setEntry(index + 2, position.getZ());
if (!isOnlyPosition()) {
final Vector3D velocity = pv.getVelocity();
value.setEntry(index + 3, velocity.getX());
value.setEntry(index + 4, velocity.getY());
value.setEntry(index + 5, velocity.getZ());
}
}
}
/** Handler for picking up Jacobians at sample dates.
* <p>
* This class is heavily based on org.orekit.estimation.leastsquares.MeasurementHandler.
* </p>
* @since 11.1
*/
private class JacobianHandler extends ValuesHandler {
/** Jacobian matrix. */
private final RealMatrix jacobian;
/** Matrices harvester. */
private final MatricesHarvester harvester;
/** Simple constructor.
* @param propagator propagator
* @param columns number of columns of the Jacobian matrix
*/
JacobianHandler(final Propagator propagator, final int columns) {
super();
this.jacobian = MatrixUtils.createRealMatrix(getTargetSize(), columns);
this.harvester = propagator.setupMatricesComputation("converter-partials", null, null);
}
/** Fill up a few Jacobian rows (either 6 or 3 depending on velocities used or not).
* @param state spacecraft state
*/
@Override
protected void fillRows(final SpacecraftState state) {
// value part
super.fillRows(state);
// Jacobian part
final RealMatrix dYdY0 = harvester.getStateTransitionMatrix(state);
final RealMatrix dYdP = harvester.getParametersJacobian(state);
final ParameterDriversList orbitalParameters = builder.getOrbitalStateFactory().getOrbitalParametersDrivers();
for (int k = 0; k < getStateSize(); k++) {
int column = 0;
for (int j = 0; j < orbitalParameters.getNbParams(); ++j) {
final ParameterDriver driver = orbitalParameters.getDrivers().get(j);
if (driver.isSelected()) {
jacobian.setEntry(getIndex() + k, column++, dYdY0.getEntry(k, j) * driver.getScale());
}
}
if (dYdP != null) {
for (int j = 0; j < dYdP.getColumnDimension(); ++j) {
final String name = harvester.getJacobiansColumnsNames().get(j);
for (final ParameterDriver driver : builder.getPropagationParametersDrivers().getDrivers()) {
if (name.equals(driver.getName())) {
jacobian.setEntry(getIndex() + k, column++, dYdP.getEntry(k, j) * driver.getScale());
}
}
}
}
}
}
}
}