DSSTGradientConverter.java
- /* Copyright 2002-2024 CS GROUP
- * Licensed to CS GROUP (CS) under one or more
- * contributor license agreements. See the NOTICE file distributed with
- * this work for additional information regarding copyright ownership.
- * CS licenses this file to You under the Apache License, Version 2.0
- * (the "License"); you may not use this file except in compliance with
- * the License. You may obtain a copy of the License at
- *
- * http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
- package org.orekit.propagation.semianalytical.dsst;
- import org.hipparchus.analysis.differentiation.Gradient;
- import org.orekit.attitudes.AttitudeProvider;
- import org.orekit.attitudes.FieldAttitude;
- import org.orekit.orbits.FieldEquinoctialOrbit;
- import org.orekit.orbits.FieldOrbit;
- import org.orekit.orbits.PositionAngleType;
- import org.orekit.propagation.FieldSpacecraftState;
- import org.orekit.propagation.SpacecraftState;
- import org.orekit.propagation.integration.AbstractGradientConverter;
- import org.orekit.time.AbsoluteDate;
- import org.orekit.time.FieldAbsoluteDate;
- /** Converter for states and parameters arrays.
- * @author Luc Maisonobe
- * @author Bryan Cazabonne
- * @since 10.2
- */
- class DSSTGradientConverter extends AbstractGradientConverter {
- /** Fixed dimension of the state. */
- private static final int FREE_STATE_PARAMETERS = 6;
- /** Simple constructor.
- * @param state regular state
- * @param provider provider to use if attitude needs to be recomputed
- */
- DSSTGradientConverter(final SpacecraftState state, final AttitudeProvider provider) {
- super(FREE_STATE_PARAMETERS);
- // equinoctial parameters always has derivatives
- final Gradient sma = Gradient.variable(FREE_STATE_PARAMETERS, 0, state.getA());
- final Gradient ex = Gradient.variable(FREE_STATE_PARAMETERS, 1, state.getEquinoctialEx());
- final Gradient ey = Gradient.variable(FREE_STATE_PARAMETERS, 2, state.getEquinoctialEy());
- final Gradient hx = Gradient.variable(FREE_STATE_PARAMETERS, 3, state.getHx());
- final Gradient hy = Gradient.variable(FREE_STATE_PARAMETERS, 4, state.getHy());
- final Gradient l = Gradient.variable(FREE_STATE_PARAMETERS, 5, state.getLM());
- final Gradient gMu = Gradient.constant(FREE_STATE_PARAMETERS, state.getMu());
- // date
- final AbsoluteDate date = state.getDate();
- final FieldAbsoluteDate<Gradient> dateField = new FieldAbsoluteDate<>(sma.getField(), date);
- // mass never has derivatives
- final Gradient gM = Gradient.constant(FREE_STATE_PARAMETERS, state.getMass());
- final FieldOrbit<Gradient> gOrbit =
- new FieldEquinoctialOrbit<>(sma, ex, ey, hx, hy, l,
- PositionAngleType.MEAN,
- state.getFrame(),
- dateField,
- gMu);
- final FieldAttitude<Gradient> gAttitude;
- // compute attitude partial derivatives
- gAttitude = provider.getAttitude(gOrbit, gOrbit.getDate(), gOrbit.getFrame());
- // initialize the list with the state having 0 force model parameters
- initStates(new FieldSpacecraftState<>(gOrbit, gAttitude, gM));
- }
- }