1   /* Copyright 2022-2025 Luc Maisonobe
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  
18  package org.orekit.files.ccsds.ndm.adm.apm;
19  
20  import org.hipparchus.linear.MatrixUtils;
21  import org.hipparchus.linear.RealMatrix;
22  import org.orekit.files.ccsds.definitions.FrameFacade;
23  import org.orekit.files.ccsds.ndm.CommonPhysicalProperties;
24  
25  /** Inertia.
26   * @author Luc Maisonobe
27   * @since 12.0
28   */
29  public class Inertia extends CommonPhysicalProperties {
30  
31      /** Inertia reference frame. */
32      private FrameFacade frame;
33  
34      /** Inertia matrix. */
35      private RealMatrix inertiaMatrix;
36  
37      /** Simple constructor.
38       */
39      public Inertia() {
40          inertiaMatrix = MatrixUtils.createRealMatrix(new double[][] {
41              { Double.NaN, Double.NaN, Double.NaN },
42              { Double.NaN, Double.NaN, Double.NaN },
43              { Double.NaN, Double.NaN, Double.NaN }
44          });
45      }
46  
47      /** {@inheritDoc} */
48      @Override
49      public void validate(final double version) {
50          super.validate(version);
51          if (version >= 2.0) {
52              checkNotNull(frame, InertiaKey.INERTIA_REF_FRAME.name());
53          }
54          checkNotNaN(inertiaMatrix.getEntry(0, 0), InertiaKey.IXX.name());
55          checkNotNaN(inertiaMatrix.getEntry(1, 1), InertiaKey.IYY.name());
56          checkNotNaN(inertiaMatrix.getEntry(2, 2), InertiaKey.IZZ.name());
57          checkNotNaN(inertiaMatrix.getEntry(0, 1), InertiaKey.IXY.name());
58          checkNotNaN(inertiaMatrix.getEntry(0, 2), InertiaKey.IXZ.name());
59          checkNotNaN(inertiaMatrix.getEntry(1, 2), InertiaKey.IYZ.name());
60      }
61  
62      /** Set frame in which inertia is specified.
63       * @param frame frame in which inertia is specified
64       */
65      public void setFrame(final FrameFacade frame) {
66          this.frame = frame;
67      }
68  
69      /** Get frame in which inertia is specified.
70       * @return frame in which inertia is specified
71       */
72      public FrameFacade getFrame() {
73          return frame;
74      }
75  
76      /** Get the inertia matrix.
77       * @return the inertia matrix
78       */
79      public RealMatrix getInertiaMatrix() {
80          return inertiaMatrix;
81      }
82  
83      /** Set an entry in the inertia matrix.
84       * <p>
85       * Both I(j, k) and I(k, j) are set.
86       * </p>
87       * @param j row index (must be between 0 and 3 (inclusive)
88       * @param k column index (must be between 0 and 3 (inclusive)
89       * @param entry value of the matrix entry
90       */
91      public void setInertiaMatrixEntry(final int j, final int k, final double entry) {
92          refuseFurtherComments();
93          inertiaMatrix.setEntry(j, k, entry);
94          inertiaMatrix.setEntry(k, j, entry);
95      }
96  
97  }