1   /* Copyright 2002-2021 CS GROUP
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.odm.ocm;
19  
20  import java.util.List;
21  
22  import org.hipparchus.linear.MatrixUtils;
23  import org.hipparchus.linear.RealMatrix;
24  import org.orekit.files.ccsds.definitions.ElementsType;
25  import org.orekit.time.AbsoluteDate;
26  import org.orekit.time.TimeStamped;
27  import org.orekit.utils.units.Unit;
28  
29  /** Covariance entry.
30   * @author Luc Maisonobe
31   * @since 11.0
32   */
33  public class Covariance implements TimeStamped {
34  
35      /** Type of the elements. */
36      private final ElementsType type;
37  
38      /** Entry date. */
39      private final AbsoluteDate date;
40  
41      /** Covariance matrix. */
42      private final RealMatrix matrix;
43  
44      /** Simple constructor.
45       * @param type type of the elements
46       * @param ordering ordering to use
47       * @param date entry date
48       * @param fields matrix elements
49       * @param first index of first field to consider
50       */
51      public Covariance(final ElementsType type, final Ordering ordering, final AbsoluteDate date,
52                        final String[] fields, final int first) {
53          final List<Unit> units = type.getUnits();
54          this.type   = type;
55          this.date   = date;
56          this.matrix = MatrixUtils.createRealMatrix(units.size(), units.size());
57          final CovarianceIndexer indexer = new CovarianceIndexer(units.size());
58          for (int k = 0; first + k < fields.length; ++k) {
59              if (!indexer.isCrossCorrelation()) {
60                  final int    i         = indexer.getRow();
61                  final int    j         = indexer.getColumn();
62                  final double raw       = Double.parseDouble(fields[first + k]);
63                  final double converted = units.get(i).toSI(units.get(j).toSI(raw));
64                  matrix.setEntry(i, j, converted);
65                  if (i != j) {
66                      matrix.setEntry(j, i, converted);
67                  }
68              }
69              ordering.update(indexer);
70          }
71      }
72  
73      /** {@inheritDoc} */
74      @Override
75      public AbsoluteDate getDate() {
76          return date;
77      }
78  
79      /** Get the covariance matrix.
80       * @return covariance matrix
81       */
82      public RealMatrix getMatrix() {
83          return matrix;
84      }
85  
86      /** Get the type of the elements.
87       * @return type of the elements
88       */
89      public ElementsType getType() {
90          return type;
91      }
92  
93  }