IntegrableJacobianColumnGenerator.java
- /* Copyright 2002-2024 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.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 yields(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
- public CombinedDerivatives combinedDerivatives(final SpacecraftState s) {
- return new CombinedDerivatives(pDot, null);
- }
- }