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5    * CS licenses this file to You under the Apache License, Version 2.0
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11   * Unless required by applicable law or agreed to in writing, software
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14   * See the License for the specific language governing permissions and
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17  package org.orekit.propagation.analytical.tle;
18  
19  import org.hipparchus.linear.RealMatrix;
20  import org.orekit.orbits.PositionAngleType;
21  import org.orekit.propagation.SpacecraftState;
22  import org.orekit.propagation.analytical.AbstractAnalyticalGradientConverter;
23  import org.orekit.propagation.analytical.AbstractAnalyticalMatricesHarvester;
24  import org.orekit.utils.DoubleArrayDictionary;
25  
26  /** Harvester between two-dimensional Jacobian matrices and
27   * one-dimensional {@link TLEPropagator}.
28   * @author Thomas Paulet
29   * @author Bryan Cazabonne
30   * @since 11.1
31   */
32  class TLEHarvester extends AbstractAnalyticalMatricesHarvester {
33  
34      /** Propagator bound to this harvester. */
35      private final TLEPropagator propagator;
36  
37      /** Simple constructor.
38       * <p>
39       * The arguments for initial matrices <em>must</em> be compatible with the
40       * {@link org.orekit.orbits.OrbitType orbit type}
41       * and {@link PositionAngleType position angle} that will be used by propagator
42       * </p>
43       * @param propagator propagator bound to this harvester
44       * @param stmName State Transition Matrix state name
45       * @param initialStm initial State Transition Matrix ∂C/∂K₀,
46       *                   if null (which is the most frequent case), assumed to be just the
47       *                   conversion from Keplerian type to Cartesian type at t₀
48       * @param initialJacobianColumns initial columns of the Jacobians matrix with respect to parameters,
49       * if null or if some selected parameters are missing from the dictionary, the corresponding
50       * initial column is assumed to be 0
51       */
52      TLEHarvester(final TLEPropagator propagator, final String stmName,
53                   final RealMatrix initialStm, final DoubleArrayDictionary initialJacobianColumns) {
54          super(propagator);
55          this.propagator = propagator;
56          setInitialStm(stmName, initialStm);
57          setInitialJacobianColumns(initialJacobianColumns);
58      }
59  
60      /** {@inheritDoc}
61       * <p>
62       * As the propagated state is Cartesian for TLE propagators, this is the Jacobian of the
63       * Cartesian coordinates with respect to the TLE mean elements representing the state.
64       * </p>
65       */
66      @Override
67      public RealMatrix getStateJacobianVsBuilderParameters(final SpacecraftState state) {
68          return propagator.getTleGenerationAlgorithm().getJacobianWrtParameters(builderParameters(state));
69      }
70  
71      /** Get the TLE whose orbital elements are the builder parameters representing a state.
72       * @param state state to represent
73       * @return TLE holding the mean elements that represent the given state
74       */
75      private TLE builderParameters(final SpacecraftState state) {
76  
77          final TLE current = propagator.getTLE();
78  
79          if (state.getDate().isEqualTo(current.getDate())) {
80              // the TLE held by the propagator already is the exact representation of the
81              // state at its own epoch, so we use it as is rather than rebuilding it, which
82              // would only add the convergence noise of the osculating to mean iterations
83              return current;
84          }
85  
86          // rebuild the mean elements matching the state, keeping the identification data
87          // (satellite number, launch data, B*, …) of the TLE held by the propagator
88          // FIXME: not sure about the performance of this one
89          return propagator.getTleGenerationAlgorithm().generate(state, current);
90  
91      }
92  
93      /** {@inheritDoc} */
94      @Override
95      public AbstractAnalyticalGradientConverter getGradientConverter() {
96          return new TLEGradientConverter(propagator);
97      }
98  
99  }