FieldNumericalPropagator.java

  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.numerical;

  19. import java.util.ArrayList;
  20. import java.util.Arrays;
  21. import java.util.Collections;
  22. import java.util.List;

  24. import org.hipparchus.CalculusFieldElement;
  25. import org.hipparchus.Field;
  26. import org.hipparchus.geometry.euclidean.threed.FieldVector3D;
  27. import org.hipparchus.ode.FieldODEIntegrator;
  28. import org.hipparchus.util.MathArrays;
  29. import org.orekit.annotation.DefaultDataContext;
  30. import org.orekit.attitudes.AttitudeProvider;
  31. import org.orekit.attitudes.AttitudeProviderModifier;
  32. import org.orekit.attitudes.FieldAttitude;
  33. import org.orekit.data.DataContext;
  34. import org.orekit.errors.OrekitException;
  35. import org.orekit.errors.OrekitIllegalArgumentException;
  36. import org.orekit.errors.OrekitInternalError;
  37. import org.orekit.errors.OrekitMessages;
  38. import org.orekit.forces.ForceModel;
  39. import org.orekit.forces.gravity.NewtonianAttraction;
  40. import org.orekit.frames.Frame;
  41. import org.orekit.orbits.FieldOrbit;
  42. import org.orekit.orbits.OrbitType;
  43. import org.orekit.orbits.PositionAngleType;
  44. import org.orekit.propagation.CartesianToleranceProvider;
  45. import org.orekit.propagation.FieldSpacecraftState;
  46. import org.orekit.propagation.PropagationType;
  47. import org.orekit.propagation.Propagator;
  48. import org.orekit.propagation.ToleranceProvider;
  49. import org.orekit.propagation.events.FieldEventDetector;
  50. import org.orekit.propagation.integration.FieldAbstractIntegratedPropagator;
  51. import org.orekit.propagation.integration.FieldStateMapper;
  52. import org.orekit.time.AbsoluteDate;
  53. import org.orekit.time.FieldAbsoluteDate;
  54. import org.orekit.utils.FieldAbsolutePVCoordinates;
  55. import org.orekit.utils.ParameterDriver;
  56. import org.orekit.utils.ParameterObserver;
  57. import org.orekit.utils.TimeSpanMap;
  58. import org.orekit.utils.TimeStampedFieldPVCoordinates;

  60. /** This class propagates {@link org.orekit.orbits.FieldOrbit orbits} using
  61.  * numerical integration.
  62.  * <p>Numerical propagation is much more accurate than analytical propagation
  63.  * like for example {@link org.orekit.propagation.analytical.KeplerianPropagator
  64.  * Keplerian} or {@link org.orekit.propagation.analytical.EcksteinHechlerPropagator
  65.  * Eckstein-Hechler}, but requires a few more steps to set up to be used properly.
  66.  * Whereas analytical propagators are configured only thanks to their various
  67.  * constructors and can be used immediately after construction, numerical propagators
  68.  * configuration involve setting several parameters between construction time
  69.  * and propagation time.</p>
  70.  * <p>The configuration parameters that can be set are:</p>
  71.  * <ul>
  72.  *   <li>the initial spacecraft state ({@link #setInitialState(FieldSpacecraftState)})</li>
  73.  *   <li>the central attraction coefficient ({@link #setMu(CalculusFieldElement)})</li>
  74.  *   <li>the various force models ({@link #addForceModel(ForceModel)},
  75.  *   {@link #removeForceModels()})</li>
  76.  *   <li>the {@link OrbitType type} of orbital parameters to be used for propagation
  77.  *   ({@link #setOrbitType(OrbitType)}),
  78.  *   <li>the {@link PositionAngleType type} of position angle to be used in orbital parameters
  79.  *   to be used for propagation where it is relevant ({@link
  80.  *   #setPositionAngleType(PositionAngleType)}),
  81.  *   <li>whether {@link org.orekit.propagation.integration.FieldAdditionalDerivativesProvider additional derivatives providers}
  82.  *   should be propagated along with orbital state
  83.  *   ({@link #addAdditionalDerivativesProvider(org.orekit.propagation.integration.FieldAdditionalDerivativesProvider)}),
  84.  *   <li>the discrete events that should be triggered during propagation
  85.  *   ({@link #addEventDetector(FieldEventDetector)},
  86.  *   {@link #clearEventsDetectors()})</li>
  87.  *   <li>the binding logic with the rest of the application ({@link #getMultiplexer()})</li>
  88.  * </ul>
  89.  * <p>From these configuration parameters, only the initial state is mandatory. The default
  90.  * propagation settings are in {@link OrbitType#EQUINOCTIAL equinoctial} parameters with
  91.  * {@link PositionAngleType#ECCENTRIC} longitude argument. If the central attraction coefficient
  92.  * is not explicitly specified, the one used to define the initial orbit will be used.
  93.  * However, specifying only the initial state and perhaps the central attraction coefficient
  94.  * would mean the propagator would use only Keplerian forces. In this case, the simpler {@link
  95.  * org.orekit.propagation.analytical.KeplerianPropagator KeplerianPropagator} class would
  96.  * perhaps be more effective.</p>
  97.  * <p>The underlying numerical integrator set up in the constructor may also have its own
  98.  * configuration parameters. Typical configuration parameters for adaptive stepsize integrators
  99.  * are the min, max and perhaps start step size as well as the absolute and/or relative errors
  100.  * thresholds.</p>
  101.  * <p>The state that is seen by the integrator is a simple seven elements double array.
  102.  * The six first elements are either:
  103.  * <ul>
  104.  *   <li>the {@link org.orekit.orbits.FieldEquinoctialOrbit equinoctial orbit parameters} (a, e<sub>x</sub>,
  105.  *   e<sub>y</sub>, h<sub>x</sub>, h<sub>y</sub>, λ<sub>M</sub> or λ<sub>E</sub>
  106.  *   or λ<sub>v</sub>) in meters and radians,</li>
  107.  *   <li>the {@link org.orekit.orbits.FieldKeplerianOrbit Keplerian orbit parameters} (a, e, i, ω, Ω,
  108.  *   M or E or v) in meters and radians,</li>
  109.  *   <li>the {@link org.orekit.orbits.FieldCircularOrbit circular orbit parameters} (a, e<sub>x</sub>, e<sub>y</sub>, i,
  110.  *   Ω, α<sub>M</sub> or α<sub>E</sub> or α<sub>v</sub>) in meters
  111.  *   and radians,</li>
  112.  *   <li>the {@link org.orekit.orbits.FieldCartesianOrbit Cartesian orbit parameters} (x, y, z, v<sub>x</sub>,
  113.  *   v<sub>y</sub>, v<sub>z</sub>) in meters and meters per seconds.
  114.  * </ul>
  115.  * The last element is the mass in kilograms.
  116.  * <p>The following code snippet shows a typical setting for Low Earth Orbit propagation in
  117.  * equinoctial parameters and true longitude argument:</p>
  118.  * <pre>
  119.  * final T          zero      = field.getZero();
  120.  * final T          dP        = zero.add(0.001);
  121.  * final T          minStep   = zero.add(0.001);
  122.  * final T          maxStep   = zero.add(500);
  123.  * final T          initStep  = zero.add(60);
  124.  * final double[][] tolerance = ToleranceProvider.getDefaultToleranceProvider(dP).getTolerances(orbit, OrbitType.EQUINOCTIAL);
  125.  * AdaptiveStepsizeFieldIntegrator&lt;T&gt; integrator = new DormandPrince853FieldIntegrator&lt;&gt;(field, minStep, maxStep, tolerance[0], tolerance[1]);
  126.  * integrator.setInitialStepSize(initStep);
  127.  * propagator = new FieldNumericalPropagator&lt;&gt;(field, integrator);
  128.  * </pre>
  129.  * <p>By default, at the end of the propagation, the propagator resets the initial state to the final state,
  130.  * thus allowing a new propagation to be started from there without recomputing the part already performed.
  131.  * This behaviour can be changed by calling {@link #setResetAtEnd(boolean)}.
  132.  * </p>
  133.  * <p>Beware the same instance cannot be used simultaneously by different threads, the class is <em>not</em>
  134.  * thread-safe.</p>

  136.  * @see FieldSpacecraftState
  137.  * @see ForceModel
  138.  * @see org.orekit.propagation.sampling.FieldOrekitStepHandler
  139.  * @see org.orekit.propagation.sampling.FieldOrekitFixedStepHandler
  140.  * @see org.orekit.propagation.integration.FieldIntegratedEphemeris
  141.  * @see FieldTimeDerivativesEquations
  142.  *
  143.  * @author Mathieu Rom&eacute;ro
  144.  * @author Luc Maisonobe
  145.  * @author Guylaine Prat
  146.  * @author Fabien Maussion
  147.  * @author V&eacute;ronique Pommier-Maurussane
  148.  * @param <T> type of the field elements
  149.  */
  150. public class FieldNumericalPropagator<T extends CalculusFieldElement<T>> extends FieldAbstractIntegratedPropagator<T> {

  152.     /** Force models used during the extrapolation of the FieldOrbit<T>, without Jacobians. */
  153.     private final List<ForceModel> forceModels;

  155.     /** Field used by this class.*/
  156.     private final Field<T> field;

  158.     /** boolean to ignore or not the creation of a NewtonianAttraction. */
  159.     private boolean ignoreCentralAttraction = false;

  161.     /**
  162.      * boolean to know if a full attitude (with rates) is needed when computing derivatives for the ODE.
  163.      */
  164.     private boolean needFullAttitudeForDerivatives = true;

  166.     /** Create a new instance of NumericalPropagator, based on orbit definition mu.
  167.      * After creation, the instance is empty, i.e. the attitude provider is set to an
  168.      * unspecified default law and there are no perturbing forces at all.
  169.      * This means that if {@link #addForceModel addForceModel} is not
  170.      * called after creation, the integrated orbit will follow a Keplerian
  171.      * evolution only. The defaults are {@link OrbitType#EQUINOCTIAL}
  172.      * for {@link #setOrbitType(OrbitType) propagation
  173.      * orbit type} and {@link PositionAngleType#ECCENTRIC} for {@link
  174.      * #setPositionAngleType(PositionAngleType) position angle type}.
  175.      *
  176.      * <p>This constructor uses the {@link DataContext#getDefault() default data context}.
  177.      *
  178.      * @param integrator numerical integrator to use for propagation.
  179.      * @param field Field used by default
  180.      * @see #FieldNumericalPropagator(Field, FieldODEIntegrator, AttitudeProvider)
  181.      */
  182.     @DefaultDataContext
  183.     public FieldNumericalPropagator(final Field<T> field, final FieldODEIntegrator<T> integrator) {
  184.         this(field, integrator, Propagator.getDefaultLaw(DataContext.getDefault().getFrames()));
  185.     }

  187.     /** Create a new instance of NumericalPropagator, based on orbit definition mu.
  188.      * After creation, the instance is empty, i.e. the attitude provider is set to an
  189.      * unspecified default law and there are no perturbing forces at all.
  190.      * This means that if {@link #addForceModel addForceModel} is not
  191.      * called after creation, the integrated orbit will follow a Keplerian
  192.      * evolution only. The defaults are {@link OrbitType#EQUINOCTIAL}
  193.      * for {@link #setOrbitType(OrbitType) propagation
  194.      * orbit type} and {@link PositionAngleType#ECCENTRIC} for {@link
  195.      * #setPositionAngleType(PositionAngleType) position angle type}.
  196.      * @param field Field used by default
  197.      * @param integrator numerical integrator to use for propagation.
  198.      * @param attitudeProvider attitude law to use.
  199.      * @since 10.1
  200.      */
  201.     public FieldNumericalPropagator(final Field<T> field,
  202.                                     final FieldODEIntegrator<T> integrator,
  203.                                     final AttitudeProvider attitudeProvider) {
  204.         super(field, integrator, PropagationType.OSCULATING);
  205.         this.field = field;
  206.         forceModels = new ArrayList<>();
  207.         initMapper(field);
  208.         setAttitudeProvider(attitudeProvider);
  209.         setMu(field.getZero().add(Double.NaN));
  210.         clearStepHandlers();
  211.         setOrbitType(NumericalPropagator.DEFAULT_ORBIT_TYPE);
  212.         setPositionAngleType(NumericalPropagator.DEFAULT_POSITION_ANGLE_TYPE);
  213.     }

  215.     /** Set the flag to ignore or not the creation of a {@link NewtonianAttraction}.
  216.      * @param ignoreCentralAttraction if true, {@link NewtonianAttraction} is <em>not</em>
  217.      * added automatically if missing
  218.      */
  219.     public void setIgnoreCentralAttraction(final boolean ignoreCentralAttraction) {
  220.         this.ignoreCentralAttraction = ignoreCentralAttraction;
  221.     }

  223.     /** Set the central attraction coefficient μ.
  224.      * <p>
  225.      * Setting the central attraction coefficient is
  226.      * equivalent to {@link #addForceModel(ForceModel) add}
  227.      * a {@link NewtonianAttraction} force model.
  228.      * </p>
  229.      * @param mu central attraction coefficient (m³/s²)
  230.      * @see #addForceModel(ForceModel)
  231.      * @see #getAllForceModels()
  232.      */
  233.     @Override
  234.     public void setMu(final T mu) {
  235.         if (ignoreCentralAttraction) {
  236.             superSetMu(mu);
  237.         } else {
  238.             addForceModel(new NewtonianAttraction(mu.getReal()));
  239.         }
  240.     }

  242.     /** Set the central attraction coefficient μ only in upper class.
  243.      * @param mu central attraction coefficient (m³/s²)
  244.      */
  245.     private void superSetMu(final T mu) {
  246.         super.setMu(mu);
  247.     }

  249.     /** Check if Newtonian attraction force model is available.
  250.      * <p>
  251.      * Newtonian attraction is always the last force model in the list.
  252.      * </p>
  253.      * @return true if Newtonian attraction force model is available
  254.      */
  255.     private boolean hasNewtonianAttraction() {
  256.         final int last = forceModels.size() - 1;
  257.         return last >= 0 && forceModels.get(last) instanceof NewtonianAttraction;
  258.     }

  260.     /** Add a force model to the global perturbation model.
  261.      * <p>If this method is not called at all, the integrated orbit will follow
  262.      * a Keplerian evolution only.</p>
  263.      * @param model perturbing {@link ForceModel} to add
  264.      * @see #removeForceModels()
  265.      * @see #setMu(CalculusFieldElement)
  266.      */
  267.     public void addForceModel(final ForceModel model) {

  269.         if (model instanceof NewtonianAttraction) {
  270.             // we want to add the central attraction force model

  272.             try {
  273.                 // ensure we are notified of any mu change
  274.                 model.getParametersDrivers().get(0).addObserver(new ParameterObserver() {
  275.                     /** {@inheritDoc} */
  276.                     @Override
  277.                     public void valueChanged(final double previousValue, final ParameterDriver driver, final AbsoluteDate date) {
  278.                         // mu PDriver should have only 1 span
  279.                         superSetMu(field.getZero().newInstance(driver.getValue(date)));
  280.                     }
  281.                     /** {@inheritDoc} */
  282.                     @Override
  283.                     public void valueSpanMapChanged(final TimeSpanMap<Double> previousValue, final ParameterDriver driver) {
  284.                         // mu PDriver should have only 1 span
  285.                         superSetMu(field.getZero().newInstance(driver.getValue()));
  286.                     }
  287.                 });
  288.             } catch (OrekitException oe) {
  289.                 // this should never happen
  290.                 throw new OrekitInternalError(oe);
  291.             }

  293.             if (hasNewtonianAttraction()) {
  294.                 // there is already a central attraction model, replace it
  295.                 forceModels.set(forceModels.size() - 1, model);
  296.             } else {
  297.                 // there are no central attraction model yet, add it at the end of the list
  298.                 forceModels.add(model);
  299.             }
  300.         } else {
  301.             // we want to add a perturbing force model
  302.             if (hasNewtonianAttraction()) {
  303.                 // insert the new force model before Newtonian attraction,
  304.                 // which should always be the last one in the list
  305.                 forceModels.add(forceModels.size() - 1, model);
  306.             } else {
  307.                 // we only have perturbing force models up to now, just append at the end of the list
  308.                 forceModels.add(model);
  309.             }
  310.         }

  312.     }

  314.     /** Remove all perturbing force models from the global perturbation model.
  315.      * <p>Once all perturbing forces have been removed (and as long as no new force
  316.      * model is added), the integrated orbit will follow a Keplerian evolution
  317.      * only.</p>
  318.      * @see #addForceModel(ForceModel)
  319.      */
  320.     public void removeForceModels() {
  321.         forceModels.clear();
  322.     }

  324.     /** Get all the force models, perturbing forces and Newtonian attraction included.
  325.      * @return list of perturbing force models, with Newtonian attraction being the
  326.      * last one
  327.      * @see #addForceModel(ForceModel)
  328.      * @see #setMu(CalculusFieldElement)
  329.      * @since 9.1
  330.      */
  331.     public List<ForceModel> getAllForceModels() {
  332.         return Collections.unmodifiableList(forceModels);
  333.     }

  335.     /** Set propagation orbit type.
  336.      * @param orbitType orbit type to use for propagation
  337.      */
  338.     @Override
  339.     public void setOrbitType(final OrbitType orbitType) {
  340.         super.setOrbitType(orbitType);
  341.     }

  343.     /** Get propagation parameter type.
  344.      * @return orbit type used for propagation
  345.      */
  346.     @Override
  347.     public OrbitType getOrbitType() {
  348.         return superGetOrbitType();
  349.     }

  351.     /** Get propagation parameter type.
  352.      * @return orbit type used for propagation
  353.      */
  354.     private OrbitType superGetOrbitType() {
  355.         return super.getOrbitType();
  356.     }

  358.     /** Set position angle type.
  359.      * <p>
  360.      * The position parameter type is meaningful only if {@link
  361.      * #getOrbitType() propagation orbit type}
  362.      * support it. As an example, it is not meaningful for propagation
  363.      * in {@link OrbitType#CARTESIAN Cartesian} parameters.
  364.      * </p>
  365.      * @param positionAngleType angle type to use for propagation
  366.      */
  367.     @Override
  368.     public void setPositionAngleType(final PositionAngleType positionAngleType) {
  369.         super.setPositionAngleType(positionAngleType);
  370.     }

  372.     /** Get propagation parameter type.
  373.      * @return angle type to use for propagation
  374.      */
  375.     @Override
  376.     public PositionAngleType getPositionAngleType() {
  377.         return super.getPositionAngleType();
  378.     }

  380.     /** Set the initial state.
  381.      * @param initialState initial state
  382.      */
  383.     public void setInitialState(final FieldSpacecraftState<T> initialState) {
  384.         resetInitialState(initialState);
  385.     }

  387.     /** {@inheritDoc} */
  388.     @Override
  389.     public void resetInitialState(final FieldSpacecraftState<T> state) {
  390.         super.resetInitialState(state);
  391.         if (!hasNewtonianAttraction()) {
  392.             setMu(state.getOrbit().getMu());
  393.         }
  394.         setStartDate(state.getDate());
  395.     }

  397.     /** {@inheritDoc} */
  398.     @Override
  399.     protected AttitudeProvider initializeAttitudeProviderForDerivatives() {
  400.         final AttitudeProvider attitudeProvider = getAttitudeProvider();
  401.         return needFullAttitudeForDerivatives ? attitudeProvider :
  402.             AttitudeProviderModifier.getFrozenAttitudeProvider(attitudeProvider);
  403.     }

  405.     /** {@inheritDoc} */
  406.     protected FieldStateMapper<T> createMapper(final FieldAbsoluteDate<T> referenceDate, final T mu,
  407.                                        final OrbitType orbitType, final PositionAngleType positionAngleType,
  408.                                        final AttitudeProvider attitudeProvider, final Frame frame) {
  409.         return new FieldOsculatingMapper(referenceDate, mu, orbitType, positionAngleType, attitudeProvider, frame);
  410.     }

  412.     /** Internal mapper using directly osculating parameters. */
  413.     private class FieldOsculatingMapper extends FieldStateMapper<T> {

  415.         /** Simple constructor.
  416.          * <p>
  417.          * The position parameter type is meaningful only if {@link
  418.          * #getOrbitType() propagation orbit type}
  419.          * support it. As an example, it is not meaningful for propagation
  420.          * in {@link OrbitType#CARTESIAN Cartesian} parameters.
  421.          * </p>
  422.          * @param referenceDate reference date
  423.          * @param mu central attraction coefficient (m³/s²)
  424.          * @param orbitType orbit type to use for mapping
  425.          * @param positionAngleType angle type to use for propagation
  426.          * @param attitudeProvider attitude provider
  427.          * @param frame inertial frame
  428.          */
  429.         FieldOsculatingMapper(final FieldAbsoluteDate<T> referenceDate, final T mu,
  430.                               final OrbitType orbitType, final PositionAngleType positionAngleType,
  431.                               final AttitudeProvider attitudeProvider, final Frame frame) {
  432.             super(referenceDate, mu, orbitType, positionAngleType, attitudeProvider, frame);
  433.         }

  435.         /** {@inheritDoc} */
  436.         public FieldSpacecraftState<T> mapArrayToState(final FieldAbsoluteDate<T> date, final T[] y, final T[] yDot,
  437.                                                        final PropagationType type) {
  438.             // the parameter type is ignored for the Numerical Propagator

  440.             final T mass = y[6];
  441.             if (mass.getReal() <= 0.0) {
  442.                 throw new OrekitException(OrekitMessages.NOT_POSITIVE_SPACECRAFT_MASS, mass);
  443.             }

  445.             if (superGetOrbitType() == null) {
  446.                 // propagation uses absolute position-velocity-acceleration
  447.                 final FieldVector3D<T> p = new FieldVector3D<>(y[0],    y[1],    y[2]);
  448.                 final FieldVector3D<T> v = new FieldVector3D<>(y[3],    y[4],    y[5]);
  449.                 final FieldVector3D<T> a;
  450.                 final FieldAbsolutePVCoordinates<T> absPva;
  451.                 if (yDot == null) {
  452.                     absPva = new FieldAbsolutePVCoordinates<>(getFrame(), new TimeStampedFieldPVCoordinates<>(date, p, v, FieldVector3D.getZero(date.getField())));
  453.                 } else {
  454.                     a = new FieldVector3D<>(yDot[3], yDot[4], yDot[5]);
  455.                     absPva = new FieldAbsolutePVCoordinates<>(getFrame(), new TimeStampedFieldPVCoordinates<>(date, p, v, a));
  456.                 }

  458.                 final FieldAttitude<T> attitude = getAttitudeProvider().getAttitude(absPva, date, getFrame());
  459.                 return new FieldSpacecraftState<>(absPva, attitude).withMass(mass);
  460.             } else {
  461.                 // propagation uses regular orbits
  462.                 final FieldOrbit<T> orbit       = superGetOrbitType().mapArrayToOrbit(y, yDot, super.getPositionAngleType(), date, getMu(), getFrame());
  463.                 final FieldAttitude<T> attitude = getAttitudeProvider().getAttitude(orbit, date, getFrame());
  464.                 return new FieldSpacecraftState<>(orbit, attitude).withMass(mass);
  465.             }
  466.         }

  468.         /** {@inheritDoc} */
  469.         public void mapStateToArray(final FieldSpacecraftState<T> state, final T[] y, final T[] yDot) {
  470.             if (superGetOrbitType() == null) {
  471.                 // propagation uses absolute position-velocity-acceleration
  472.                 final FieldVector3D<T> p = state.getAbsPVA().getPosition();
  473.                 final FieldVector3D<T> v = state.getAbsPVA().getVelocity();
  474.                 y[0] = p.getX();
  475.                 y[1] = p.getY();
  476.                 y[2] = p.getZ();
  477.                 y[3] = v.getX();
  478.                 y[4] = v.getY();
  479.                 y[5] = v.getZ();
  480.                 y[6] = state.getMass();
  481.             }
  482.             else {
  483.                 superGetOrbitType().mapOrbitToArray(state.getOrbit(), super.getPositionAngleType(), y, yDot);
  484.                 y[6] = state.getMass();
  485.             }
  486.         }

  488.     }

  490.     /** {@inheritDoc} */
  491.     protected MainStateEquations<T> getMainStateEquations(final FieldODEIntegrator<T> integrator) {
  492.         return new Main(integrator);
  493.     }

  495.     /** Internal class for osculating parameters integration. */
  496.     private class Main implements MainStateEquations<T>, FieldTimeDerivativesEquations<T> {

  498.         /** Derivatives array. */
  499.         private final T[] yDot;

  501.         /** Current state. */
  502.         private FieldSpacecraftState<T> currentState;

  504.         /** Jacobian of the orbital parameters with respect to the Cartesian parameters. */
  505.         private T[][] jacobian;

  507.         /** Flag keeping track whether Jacobian matrix needs to be recomputed or not. */
  508.         private boolean recomputingJacobian;

  510.         /** Simple constructor.
  511.          * @param integrator numerical integrator to use for propagation.
  512.          */
  513.         Main(final FieldODEIntegrator<T> integrator) {

  515.             this.yDot     = MathArrays.buildArray(getField(),  7);
  516.             this.jacobian = MathArrays.buildArray(getField(),  6, 6);
  517.             this.recomputingJacobian = true;

  519.             // feed internal event detectors
  520.             for (final ForceModel forceModel : forceModels) {
  521.                 forceModel.getFieldEventDetectors(getField()).forEach(detector -> setUpEventDetector(integrator, detector));
  522.             }
  523.             getAttitudeProvider().getFieldEventDetectors(getField()).forEach(detector -> setUpEventDetector(integrator, detector));

  525.             // default value for Jacobian is identity
  526.             for (int i = 0; i < jacobian.length; ++i) {
  527.                 Arrays.fill(jacobian[i], getField().getZero());
  528.                 jacobian[i][i] = getField().getOne();
  529.             }

  531.         }

  533.         /** {@inheritDoc} */
  534.         @Override
  535.         public void init(final FieldSpacecraftState<T> initialState, final FieldAbsoluteDate<T> target) {
  536.             needFullAttitudeForDerivatives = forceModels.stream().anyMatch(ForceModel::dependsOnAttitudeRate);

  538.             forceModels.forEach(fm -> fm.init(initialState, target));

  540.             final int numberOfForces = forceModels.size();
  541.             final OrbitType orbitType = superGetOrbitType();
  542.             if (orbitType != null && orbitType != OrbitType.CARTESIAN && numberOfForces > 0) {
  543.                 if (numberOfForces > 1) {
  544.                     recomputingJacobian = true;
  545.                 } else {
  546.                     recomputingJacobian = !(forceModels.get(0) instanceof NewtonianAttraction);
  547.                 }
  548.             } else {
  549.                 recomputingJacobian = false;
  550.             }
  551.         }

  553.         /** {@inheritDoc} */
  554.         @Override
  555.         public T[] computeDerivatives(final FieldSpacecraftState<T> state) {
  556.             final T zero = state.getMass().getField().getZero();
  557.             currentState = state;
  558.             Arrays.fill(yDot, zero);
  559.             if (recomputingJacobian) {
  560.                 // propagation uses Jacobian matrix of orbital parameters w.r.t. Cartesian ones
  561.                 currentState.getOrbit().getJacobianWrtCartesian(getPositionAngleType(), jacobian);
  562.             }

  564.             // compute the contributions of all perturbing forces,
  565.             // using the Kepler contribution at the end since
  566.             // NewtonianAttraction is always the last instance in the list
  567.             for (final ForceModel forceModel : forceModels) {
  568.                 forceModel.addContribution(state, this);
  569.             }

  571.             if (superGetOrbitType() == null) {
  572.                 // position derivative is velocity, and was not added above in the force models
  573.                 // (it is added when orbit type is non-null because NewtonianAttraction considers it)
  574.                 final FieldVector3D<T> velocity = currentState.getPVCoordinates().getVelocity();
  575.                 yDot[0] = yDot[0].add(velocity.getX());
  576.                 yDot[1] = yDot[1].add(velocity.getY());
  577.                 yDot[2] = yDot[2].add(velocity.getZ());
  578.             }

  580.             return yDot.clone();

  582.         }

  584.         /** {@inheritDoc} */
  585.         @Override
  586.         public void addKeplerContribution(final T mu) {
  587.             if (superGetOrbitType() == null) {

  589.                 // if mu is neither 0 nor NaN, we want to include Newtonian acceleration
  590.                 if (mu.getReal() > 0) {
  591.                     // velocity derivative is Newtonian acceleration
  592.                     final FieldVector3D<T> position = currentState.getPosition();
  593.                     final T r2         = position.getNormSq();
  594.                     final T coeff      = r2.multiply(r2.sqrt()).reciprocal().negate().multiply(mu);
  595.                     yDot[3] = yDot[3].add(coeff.multiply(position.getX()));
  596.                     yDot[4] = yDot[4].add(coeff.multiply(position.getY()));
  597.                     yDot[5] = yDot[5].add(coeff.multiply(position.getZ()));
  598.                 }

  600.             } else {
  601.                 // propagation uses regular orbits
  602.                 currentState.getOrbit().addKeplerContribution(getPositionAngleType(), mu, yDot);
  603.             }
  604.         }

  606.         /** {@inheritDoc} */
  607.         @Override
  608.         public void addNonKeplerianAcceleration(final FieldVector3D<T> gamma) {
  609.             for (int i = 0; i < 6; ++i) {
  610.                 final T[] jRow = jacobian[i];
  611.                 yDot[i] = yDot[i].add(jRow[3].linearCombination(jRow[3], gamma.getX(),
  612.                                                                 jRow[4], gamma.getY(),
  613.                                                                 jRow[5], gamma.getZ()));
  614.             }
  615.         }

  617.         /** {@inheritDoc} */
  618.         @Override
  619.         public void addMassDerivative(final T q) {
  620.             if (q.getReal() > 0) {
  621.                 throw new OrekitIllegalArgumentException(OrekitMessages.POSITIVE_FLOW_RATE, q);
  622.             }
  623.             yDot[6] = yDot[6].add(q);
  624.         }

  626.     }

  628.     /** Estimate tolerance vectors for integrators.
  629.      * <p>
  630.      * The errors are estimated from partial derivatives properties of orbits,
  631.      * starting from a scalar position error specified by the user.
  632.      * Considering the energy conservation equation V = sqrt(mu (2/r - 1/a)),
  633.      * we get at constant energy (i.e. on a Keplerian trajectory):
  634.      * <pre>
  635.      * V r² |dV| = mu |dr|
  636.      * </pre>
  637.      * So we deduce a scalar velocity error consistent with the position error.
  638.      * From here, we apply orbits Jacobians matrices to get consistent errors
  639.      * on orbital parameters.
  640.      * <p>
  641.      * The tolerances are only <em>orders of magnitude</em>, and integrator tolerances
  642.      * are only local estimates, not global ones. So some care must be taken when using
  643.      * these tolerances. Setting 1mm as a position error does NOT mean the tolerances
  644.      * will guarantee a 1mm error position after several orbits integration.
  645.      * </p>
  646.      * @param dP user specified position error
  647.      * @param orbit reference orbit
  648.      * @param type propagation type for the meaning of the tolerance vectors elements
  649.      * (it may be different from {@code orbit.getType()})
  650.      * @return a two rows array, row 0 being the absolute tolerance error and row 1
  651.      * being the relative tolerance error
  652.      * @param <T> elements type
  653.      * @deprecated since 13.0. Use {@link ToleranceProvider} for default and custom tolerances.
  654.      */
  655.     @Deprecated
  656.     public static <T extends CalculusFieldElement<T>> double[][] tolerances(final T dP, final FieldOrbit<T> orbit,
  657.                                                                             final OrbitType type) {

  659.         return ToleranceProvider.getDefaultToleranceProvider(dP.getReal()).getTolerances(orbit, type, PositionAngleType.TRUE);
  660.     }

  662.     /** Estimate tolerance vectors for integrators when propagating in orbits.
  663.      * <p>
  664.      * The errors are estimated from partial derivatives properties of orbits,
  665.      * starting from scalar position and velocity errors specified by the user.
  666.      * <p>
  667.      * The tolerances are only <em>orders of magnitude</em>, and integrator tolerances
  668.      * are only local estimates, not global ones. So some care must be taken when using
  669.      * these tolerances. Setting 1mm as a position error does NOT mean the tolerances
  670.      * will guarantee a 1mm error position after several orbits integration.
  671.      * </p>
  672.      * @param <T> elements type
  673.      * @param dP user specified position error
  674.      * @param dV user specified velocity error
  675.      * @param orbit reference orbit
  676.      * @param type propagation type for the meaning of the tolerance vectors elements
  677.      * (it may be different from {@code orbit.getType()})
  678.      * @return a two rows array, row 0 being the absolute tolerance error and row 1
  679.      * being the relative tolerance error
  680.      * @since 10.3
  681.      * @deprecated since 13.0. Use {@link ToleranceProvider} for default and custom tolerances.
  682.      */
  683.     @Deprecated
  684.     public static <T extends CalculusFieldElement<T>> double[][] tolerances(final T dP, final T dV,
  685.                                                                             final FieldOrbit<T> orbit,
  686.                                                                             final OrbitType type) {

  688.         return ToleranceProvider.of(CartesianToleranceProvider.of(dP.getReal(), dV.getReal(),
  689.                 CartesianToleranceProvider.DEFAULT_ABSOLUTE_MASS_TOLERANCE)).getTolerances(orbit, type, PositionAngleType.TRUE);
  690.     }

  692. }
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