1   /* Copyright 2002-2025 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.analytical;
18  
19  import java.util.Collections;
20  import java.util.List;
21  
22  import org.hipparchus.analysis.differentiation.Gradient;
23  import org.orekit.attitudes.AttitudeProvider;
24  import org.orekit.propagation.FieldSpacecraftState;
25  import org.orekit.utils.ParameterDriver;
26  
27  /**
28   * Converter for Keplerian propagator.
29   *
30   * @author Bryan Cazabonne
31   * @since 11.1
32   */
33  class KeplerianGradientConverter extends AbstractAnalyticalGradientConverter {
34  
35      /** Fixed dimension of the state. */
36      public static final int FREE_STATE_PARAMETERS = 6;
37  
38      /** Orbit propagator. */
39      private final KeplerianPropagator propagator;
40  
41      /** Simple constructor.
42       * @param propagator orbit propagator used to access initial orbit
43       */
44      KeplerianGradientConverter(final KeplerianPropagator propagator) {
45          super(propagator, FREE_STATE_PARAMETERS);
46          // Initialize fields
47          this.propagator = propagator;
48      }
49  
50      /** {@inheritDoc} */
51      @Override
52      public FieldKeplerianPropagator<Gradient> getPropagator() {
53  
54          final FieldSpacecraftState<Gradient> state = getState(this);
55  
56          // Model parameters
57          final AttitudeProvider provider = propagator.getAttitudeProvider();
58  
59          // Central attraction coefficient
60          final Gradient mu = state.getMass().newInstance(propagator.getInitialState().getOrbit().getMu());
61  
62          // Return the "Field" propagator
63          return new FieldKeplerianPropagator<>(state.getOrbit(), provider, mu);
64  
65      }
66  
67      /** {@inheritDoc} */
68      @Override
69      public List<ParameterDriver> getParametersDrivers() {
70          return Collections.emptyList();
71      }
72  
73  }