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  package org.orekit.propagation.numerical;
18  
19  import org.orekit.propagation.SpacecraftState;
20  import org.orekit.utils.ParameterDriversList;
21  
22  /** Mapper between two-dimensional Jacobian matrices and one-dimensional {@link
23   * SpacecraftState#getAdditionalState(String) additional state arrays}.
24   * <p>
25   * This class does not hold the states by itself. Instances of this class are guaranteed
26   * to be immutable.
27   * </p>
28   * @author Vincent Mouraux
29   * @see org.orekit.propagation.numerical.PartialDerivativesEquations
30   * @see org.orekit.propagation.numerical.NumericalPropagator
31   * @see SpacecraftState#getAdditionalState(String)
32   * @see org.orekit.propagation.AbstractPropagator
33   * @since 10.2
34   */
35  public class AbsoluteJacobiansMapper extends JacobiansMapper {
36  
37      /** State dimension, fixed to 6. */
38      public static final int STATE_DIMENSION = 6;
39  
40      /** Simple constructor.
41       * @param name name of the Jacobians
42       * @param parameters selected parameters for Jacobian computation
43       */
44      public AbsoluteJacobiansMapper(final String name, final ParameterDriversList parameters) {
45          // orbit type and angle type are not used here
46          super(name, parameters, null, null);
47      }
48  
49      /** {@inheritDoc} */
50      @Override
51      protected double[][] getConversionJacobian(final SpacecraftState state) {
52  
53          final double[][] identity = new double[STATE_DIMENSION][STATE_DIMENSION];
54  
55          for (int i = 0; i < STATE_DIMENSION; ++i) {
56              identity[i][i] = 1.0;
57          }
58  
59          return identity;
60  
61      }
62  
63  }