IntegrableJacobianColumnGenerator.java
/* Copyright 2002-2022 CS GROUP
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* 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,
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package org.orekit.propagation.numerical;
import org.orekit.propagation.SpacecraftState;
import org.orekit.propagation.integration.AdditionalDerivativesProvider;
import org.orekit.propagation.integration.CombinedDerivatives;
/** Generator for one column of a Jacobian matrix.
* <p>
* This generator is based on variational equations, so
* it implements {@link AdditionalDerivativesProvider} and
* computes only the derivative of the Jacobian column, to
* be integrated by the propagator alongside the primary state.
* </p>
* @author Luc Maisonobe
* @since 11.1
*/
class IntegrableJacobianColumnGenerator
implements AdditionalDerivativesProvider, StateTransitionMatrixGenerator.PartialsObserver {
/** Name of the state for State Transition Matrix. */
private final String stmName;
/** Name of the parameter corresponding to the column. */
private final String columnName;
/** Last value computed for the partial derivatives. */
private final double[] pDot;
/** Simple constructor.
* <p>
* The generator for State Transition Matrix <em>must</em> be registered as
* an integrable generator to the same propagator as the instance, as it
* must be scheduled to update the state before the instance
* </p>
* @param stmGenerator generator for State Transition Matrix
* @param columnName name of the parameter corresponding to the column
*/
IntegrableJacobianColumnGenerator(final StateTransitionMatrixGenerator stmGenerator, final String columnName) {
this.stmName = stmGenerator.getName();
this.columnName = columnName;
this.pDot = new double[getDimension()];
stmGenerator.addObserver(columnName, this);
}
/** {@inheritDoc} */
@Override
public String getName() {
return columnName;
}
/** Get the dimension of the generated column.
* @return dimension of the generated column
*/
public int getDimension() {
return 6;
}
/** {@inheritDoc}
* <p>
* The column derivative can be computed only if the State Transition Matrix derivatives
* are available, as it implies the STM generator has already been run.
* </p>
*/
@Override
public boolean yield(final SpacecraftState state) {
return !state.hasAdditionalStateDerivative(stmName);
}
/** {@inheritDoc} */
@Override
public void partialsComputed(final SpacecraftState state, final double[] factor, final double[] accelerationPartials) {
// retrieve current Jacobian column
final double[] p = state.getAdditionalState(getName());
// compute time derivative of the Jacobian column
StateTransitionMatrixGenerator.multiplyMatrix(factor, p, pDot, 1);
pDot[3] += accelerationPartials[0];
pDot[4] += accelerationPartials[1];
pDot[5] += accelerationPartials[2];
}
/** {@inheritDoc} */
@Override
@Deprecated
public double[] derivatives(final SpacecraftState state) {
return combinedDerivatives(state).getAdditionalDerivatives();
}
/** {@inheritDoc} */
@Override
public CombinedDerivatives combinedDerivatives(final SpacecraftState s) {
return new CombinedDerivatives(pDot, null);
}
}