Duration.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.forces.maneuvers.jacobians;
- import org.orekit.propagation.AdditionalStateProvider;
- import org.orekit.propagation.SpacecraftState;
- /** Generator for one column of a Jacobian matrix for special case of maneuver duration.
- * <p>
- * Typical use cases for this are estimation of maneuver duration during
- * either orbit determination or maneuver optimization.
- * </p>
- * @author Luc Maisonobe
- * @since 11.1
- * @see MedianDate
- * @see TriggerDate
- */
- public class Duration implements AdditionalStateProvider {
- /** Name of the parameter corresponding to the start date. */
- private final String startName;
- /** Name of the parameter corresponding to the stop date. */
- private final String stopName;
- /** Name of the parameter corresponding to the column. */
- private final String columnName;
- /** Simple constructor.
- * @param startName name of the parameter corresponding to the start date
- * @param stopName name of the parameter corresponding to the stop date
- * @param columnName name of the parameter corresponding to the column
- */
- public Duration(final String startName, final String stopName, final String columnName) {
- this.startName = startName;
- this.stopName = stopName;
- this.columnName = columnName;
- }
- /** {@inheritDoc} */
- @Override
- public String getName() {
- return columnName;
- }
- /** {@inheritDoc}
- * <p>
- * The column state can be computed only if the start and stop dates columns are available.
- * </p>
- */
- @Override
- public boolean yields(final SpacecraftState state) {
- return !(state.hasAdditionalState(startName) && state.hasAdditionalState(stopName));
- }
- /** {@inheritDoc} */
- @Override
- public double[] getAdditionalState(final SpacecraftState state) {
- // compute partial derivatives with respect to start and stop dates
- final double[] dYdT0 = state.getAdditionalState(startName);
- final double[] dYdT1 = state.getAdditionalState(stopName);
- // combine derivatives to get partials with respect to duration
- final double[] dYdTm = new double[dYdT0.length];
- for (int i = 0; i < dYdTm.length; ++i) {
- dYdTm[i] = 0.5 * (dYdT1[i] - dYdT0[i]);
- }
- return dYdTm;
- }
- }