TLEPartialDerivativesEquations.java

/* Copyright 2002-2022 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
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 *
 *   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,
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package org.orekit.propagation.analytical.tle;

import org.orekit.errors.OrekitException;
import org.orekit.errors.OrekitMessages;
import org.orekit.propagation.SpacecraftState;
import org.orekit.propagation.analytical.AbstractAnalyticalPropagator;
import org.orekit.utils.ParameterDriver;
import org.orekit.utils.ParameterDriversList;

/** Set of additional equations computing the partial derivatives
 * of the state (orbit) with respect to initial state.
 * <p>
 * This set of equations are automatically added to an {@link AbstractAnalyticalPropagator analytical propagator}
 * in order to compute partial derivatives of the orbit along with the orbit itself. This is
 * useful for example in orbit determination applications.
 * </p>
 * <p>
 * The partial derivatives with respect to initial state are dimension 6 (orbit only).
 * </p>
 * @author Bryan Cazabonne
 * @author Thomas Paulet
 * @since 11.0
 */
@Deprecated
public class TLEPartialDerivativesEquations {

    /** Propagator computing state evolution. */
    private final TLEPropagator propagator;

    /** Selected parameters for Jacobian computation. */
    private ParameterDriversList selected;

    /** Name. */
    private final String name;

    /** Flag for Jacobian matrices initialization. */
    private boolean initialized;

    /** Simple constructor.
     * <p>
     * Instance regrouping equations to compute derivatives.
     * </p>
     * @param name name of the partial derivatives equations
     * @param propagator the propagator that will handle the orbit propagation
     */
    public TLEPartialDerivativesEquations(final String name,
                                          final TLEPropagator propagator) {
        this.name        = name;
        this.selected    = null;
        this.propagator  = propagator;
        this.initialized = false;
    }

    /** Get the name of the additional state.
     * @return name of the additional state
     */
    public String getName() {
        return name;
    }

    /** Freeze the selected parameters from the force models.
     */
    private void freezeParametersSelection() {
        if (selected == null) {
            // create new selected parameter driver list
            selected = new ParameterDriversList();
            for (final ParameterDriver driver : propagator.getTLE().getParametersDrivers()) {
                if (driver.isSelected()) {
                    selected.add(driver);
                }
            }
        }
    }

    /** Set the initial value of the Jacobian with respect to state and parameter.
     * <p>
     * This method is equivalent to call {@link #setInitialJacobians(SpacecraftState,
     * double[][], double[][])} with dYdY0 set to the identity matrix and dYdP set
     * to a zero matrix.
     * </p>
     * <p>
     * The force models parameters for which partial derivatives are desired,
     * <em>must</em> have been {@link ParameterDriver#setSelected(boolean) selected}
     * before this method is called, so proper matrices dimensions are used.
     * </p>
     * @param s0 initial state
     * @return state with initial Jacobians added
     */
    public SpacecraftState setInitialJacobians(final SpacecraftState s0) {
        freezeParametersSelection();
        final int stateDimension = 6;
        final double[][] dYdY0 = new double[stateDimension][stateDimension];
        final double[][] dYdP  = new double[stateDimension][selected.getNbParams()];
        for (int i = 0; i < stateDimension; ++i) {
            dYdY0[i][i] = 1.0;
        }
        return setInitialJacobians(s0, dYdY0, dYdP);
    }

    /** Set the initial value of the Jacobian with respect to state and parameter.
     * <p>
     * The returned state must be added to the propagator (it is not done
     * automatically, as the user may need to add more states to it).
     * </p>
     * @param s1 current state
     * @param dY1dY0 Jacobian of current state at time t₁ with respect
     * to state at some previous time t₀ (must be 6x6)
     * @param dY1dP Jacobian of current state at time t₁ with respect
     * to parameters (may be null if no parameters are selected)
     * @return state with initial Jacobians added
     */
    public SpacecraftState setInitialJacobians(final SpacecraftState s1,
                                               final double[][] dY1dY0, final double[][] dY1dP) {

        freezeParametersSelection();

        // Check dimensions
        final int stateDim = dY1dY0.length;
        if (stateDim != 6 || stateDim != dY1dY0[0].length) {
            throw new OrekitException(OrekitMessages.STATE_JACOBIAN_NOT_6X6,
                                      stateDim, dY1dY0[0].length);
        }
        if (dY1dP != null && stateDim != dY1dP.length) {
            throw new OrekitException(OrekitMessages.STATE_AND_PARAMETERS_JACOBIANS_ROWS_MISMATCH,
                                      stateDim, dY1dP.length);
        }
        if (dY1dP == null && selected.getNbParams() != 0 ||
            dY1dP != null && selected.getNbParams() != dY1dP[0].length) {
            throw new OrekitException(new OrekitException(OrekitMessages.INITIAL_MATRIX_AND_PARAMETERS_NUMBER_MISMATCH,
                                                          dY1dP == null ? 0 : dY1dP[0].length, selected.getNbParams()));
        }

        // store the matrices as a single dimension array
        initialized = true;
        final TLEJacobiansMapper mapper = getMapper();
        final double[] p = new double[mapper.getAdditionalStateDimension()];
        mapper.setInitialJacobians(s1, dY1dY0, dY1dP, p);

        // set value in propagator
        return s1.addAdditionalState(name, p);

    }

    /** Get a mapper between two-dimensional Jacobians and one-dimensional additional state.
     * @return a mapper between two-dimensional Jacobians and one-dimensional additional state,
     * with the same name as the instance
     * @see #setInitialJacobians(SpacecraftState)
     * @see #setInitialJacobians(SpacecraftState, double[][], double[][])
     */
    public TLEJacobiansMapper getMapper() {
        if (!initialized) {
            throw new OrekitException(OrekitMessages.STATE_JACOBIAN_NOT_INITIALIZED);
        }
        return new TLEJacobiansMapper(name, selected, propagator);
    }

}