BrouwerLyddaneGradientConverter.java

  1. /* Copyright 2002-2022 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. import java.util.List;

  19. import org.hipparchus.analysis.differentiation.Gradient;
  20. import org.orekit.attitudes.AttitudeProvider;
  21. import org.orekit.propagation.FieldSpacecraftState;
  22. import org.orekit.utils.ParameterDriver;

  23. /**
  24.  * Converter for Brouwer-Lyddane propagator.
  25.  *
  26.  * @author Bryan Cazabonne
  27.  * @since 11.1
  28.  */
  29. class BrouwerLyddaneGradientConverter extends AbstractAnalyticalGradientConverter {

  30.     /** Fixed dimension of the state. */
  31.     public static final int FREE_STATE_PARAMETERS = 6;

  32.     /** Orbit propagator. */
  33.     private final BrouwerLyddanePropagator propagator;

  34.     /** Simple constructor.
  35.      * @param propagator orbit propagator used to access initial orbit
  36.      */
  37.     BrouwerLyddaneGradientConverter(final BrouwerLyddanePropagator propagator) {
  38.         super(propagator, propagator.getMu(), FREE_STATE_PARAMETERS);
  39.         // Initialize fields
  40.         this.propagator = propagator;
  41.     }

  42.     /** {@inheritDoc} */
  43.     @Override
  44.     public FieldBrouwerLyddanePropagator<Gradient> getPropagator(final FieldSpacecraftState<Gradient> state,
  45.                                                                  final Gradient[] parameters) {

  46.         // Zero
  47.         final Gradient zero = state.getA().getField().getZero();

  48.         // Model parameters
  49.         final double[]         ck0      = propagator.getCk0();
  50.         final double           radius   = propagator.getReferenceRadius();
  51.         final AttitudeProvider provider = propagator.getAttitudeProvider();

  52.         // Central attraction coefficient
  53.         final Gradient mu = zero.add(propagator.getMu());

  54.         // Return the "Field" propagator
  55.         return new FieldBrouwerLyddanePropagator<Gradient>(state.getOrbit(), provider, radius, mu,
  56.                                                            ck0[2], ck0[3], ck0[4], ck0[5], parameters[0].getValue());

  57.     }

  58.     /** {@inheritDoc} */
  59.     @Override
  60.     public List<ParameterDriver> getParametersDrivers() {
  61.         return propagator.getParametersDrivers();
  62.     }

  63. }