1   /* Copyright 2022-2026 Romain Serra
2    * Licensed to CS GROUP (CS) under one or more
3    * contributor license agreements.  See the NOTICE file distributed with
4    * this work for additional information regarding copyright ownership.
5    * CS licenses this file to You under the Apache License, Version 2.0
6    * (the "License"); you may not use this file except in compliance with
7    * the License.  You may obtain a copy of the License at
8    *
9    *   http://www.apache.org/licenses/LICENSE-2.0
10   *
11   * Unless required by applicable law or agreed to in writing, software
12   * distributed under the License is distributed on an "AS IS" BASIS,
13   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14   * See the License for the specific language governing permissions and
15   * limitations under the License.
16   */
17  package org.orekit.control.indirect.adjoint.cost;
18  
19  
20  import org.hipparchus.util.FastMath;
21  import org.orekit.propagation.events.EventDetectionSettings;
22  import org.orekit.propagation.events.EventDetector;
23  import org.orekit.propagation.events.handlers.ResetDerivativesOnEvent;
24  
25  /**
26   * Abstract class for cost with Cartesian coordinates.
27   *
28   * @author Romain Serra
29   * @see CartesianCost
30   * @since 13.0
31   */
32  public abstract class AbstractCartesianCost implements CartesianCost {
33  
34      /** Name of adjoint vector. */
35      private final String name;
36  
37      /** Mass flow rate factor (always positive). */
38      private final double massFlowRateFactor;
39  
40      /** Dimension of adjoint vector. */
41      private final int adjointDimension;
42  
43      /**
44       * Constructor.
45       * @param name name
46       * @param massFlowRateFactor mass flow rate factor
47       */
48      protected AbstractCartesianCost(final String name, final double massFlowRateFactor) {
49          this.name = name;
50          this.massFlowRateFactor = FastMath.abs(massFlowRateFactor);
51          this.adjointDimension = this.massFlowRateFactor == 0. ? 6 : 7;
52      }
53  
54      /**
55       * {@inheritDoc}
56       */
57      @Override
58      public int getAdjointDimension() {
59          return adjointDimension;
60      }
61  
62      /**
63       * Getter for adjoint vector name.
64       * @return name
65       */
66      @Override
67      public String getAdjointName() {
68          return name;
69      }
70  
71      /** {@inheritDoc} */
72      @Override
73      public double getMassFlowRateFactor() {
74          return massFlowRateFactor;
75      }
76  
77      /**
78       * Computes the Euclidean norm of the adjoint velocity vector.
79       * @param adjointVariables adjoint vector
80       * @return norm of adjoint velocity
81       */
82      protected double getAdjointVelocityNorm(final double[] adjointVariables) {
83          return FastMath.sqrt(adjointVariables[3] * adjointVariables[3] + adjointVariables[4] * adjointVariables[4] + adjointVariables[5] * adjointVariables[5]);
84      }
85  
86      /**
87       * Build event detector for control switches.
88       * @param controlSwitchFunction switch function
89       * @param detectionSettings event detection settings
90       * @return event detector
91       * @since 14.0
92       */
93      protected EventDetector buildSwitchDetector(final ControlSwitchFunction controlSwitchFunction,
94                                                  final EventDetectionSettings detectionSettings) {
95          return EventDetector.of(controlSwitchFunction, new ResetDerivativesOnEvent(), detectionSettings);
96      }
97  }