FieldNumericalPropagator.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.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.FieldAttitude;
  32. import org.orekit.data.DataContext;
  33. import org.orekit.errors.OrekitException;
  34. import org.orekit.errors.OrekitIllegalArgumentException;
  35. import org.orekit.errors.OrekitInternalError;
  36. import org.orekit.errors.OrekitMessages;
  37. import org.orekit.forces.ForceModel;
  38. import org.orekit.forces.gravity.NewtonianAttraction;
  39. import org.orekit.frames.Frame;
  40. import org.orekit.orbits.FieldOrbit;
  41. import org.orekit.orbits.OrbitType;
  42. import org.orekit.orbits.PositionAngle;
  43. import org.orekit.propagation.FieldSpacecraftState;
  44. import org.orekit.propagation.PropagationType;
  45. import org.orekit.propagation.Propagator;
  46. import org.orekit.propagation.events.FieldEventDetector;
  47. import org.orekit.propagation.integration.FieldAbstractIntegratedPropagator;
  48. import org.orekit.propagation.integration.FieldStateMapper;
  49. import org.orekit.time.FieldAbsoluteDate;
  50. import org.orekit.utils.FieldAbsolutePVCoordinates;
  51. import org.orekit.utils.FieldPVCoordinates;
  52. import org.orekit.utils.ParameterDriver;
  53. import org.orekit.utils.ParameterObserver;
  54. import org.orekit.utils.TimeStampedFieldPVCoordinates;

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

  132.  * @see FieldSpacecraftState
  133.  * @see ForceModel
  134.  * @see org.orekit.propagation.sampling.FieldOrekitStepHandler
  135.  * @see org.orekit.propagation.sampling.FieldOrekitFixedStepHandler
  136.  * @see org.orekit.propagation.integration.FieldIntegratedEphemeris
  137.  * @see FieldTimeDerivativesEquations
  138.  *
  139.  * @author Mathieu Rom&eacute;ro
  140.  * @author Luc Maisonobe
  141.  * @author Guylaine Prat
  142.  * @author Fabien Maussion
  143.  * @author V&eacute;ronique Pommier-Maurussane
  144.  */
  145. public class FieldNumericalPropagator<T extends CalculusFieldElement<T>> extends FieldAbstractIntegratedPropagator<T> {

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

  150.     /** Field used by this class.*/
  151.     private final Field<T> field;

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

  156.     /** Create a new instance of NumericalPropagator, based on orbit definition mu.
  157.      * After creation, the instance is empty, i.e. the attitude provider is set to an
  158.      * unspecified default law and there are no perturbing forces at all.
  159.      * This means that if {@link #addForceModel addForceModel} is not
  160.      * called after creation, the integrated orbit will follow a Keplerian
  161.      * evolution only. The defaults are {@link OrbitType#EQUINOCTIAL}
  162.      * for {@link #setOrbitType(OrbitType) propagation
  163.      * orbit type} and {@link PositionAngle#TRUE} for {@link
  164.      * #setPositionAngleType(PositionAngle) position angle type}.
  165.      *
  166.      * <p>This constructor uses the {@link DataContext#getDefault() default data context}.
  167.      *
  168.      * @param integrator numerical integrator to use for propagation.
  169.      * @param field Field used by default
  170.      * @see #FieldNumericalPropagator(Field, FieldODEIntegrator, AttitudeProvider)
  171.      */
  172.     @DefaultDataContext
  173.     public FieldNumericalPropagator(final Field<T> field, final FieldODEIntegrator<T> integrator) {
  174.         this(field, integrator, Propagator.getDefaultLaw(DataContext.getDefault().getFrames()));
  175.     }

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

  205.     /** Set the flag to ignore or not the creation of a {@link NewtonianAttraction}.
  206.      * @param ignoreCentralAttraction if true, {@link NewtonianAttraction} is <em>not</em>
  207.      * added automatically if missing
  208.      */
  209.     public void setIgnoreCentralAttraction(final boolean ignoreCentralAttraction) {
  210.         this.ignoreCentralAttraction = ignoreCentralAttraction;
  211.     }

  213.      /** Set the central attraction coefficient μ.
  214.       * <p>
  215.       * Setting the central attraction coefficient is
  216.       * equivalent to {@link #addForceModel(ForceModel) add}
  217.       * a {@link NewtonianAttraction} force model.
  218.       * </p>
  219.      * @param mu central attraction coefficient (m³/s²)
  220.      * @see #addForceModel(ForceModel)
  221.      * @see #getAllForceModels()
  222.      */
  223.     public void setMu(final T mu) {
  224.         if (ignoreCentralAttraction) {
  225.             superSetMu(mu);
  226.         } else {
  227.             addForceModel(new NewtonianAttraction(mu.getReal()));
  228.         }
  229.     }

  231.     /** Set the central attraction coefficient μ only in upper class.
  232.      * @param mu central attraction coefficient (m³/s²)
  233.      */
  234.     private void superSetMu(final T mu) {
  235.         super.setMu(mu);
  236.     }

  238.     /** Check if Newtonian attraction force model is available.
  239.      * <p>
  240.      * Newtonian attraction is always the last force model in the list.
  241.      * </p>
  242.      * @return true if Newtonian attraction force model is available
  243.      */
  244.     private boolean hasNewtonianAttraction() {
  245.         final int last = forceModels.size() - 1;
  246.         return last >= 0 && forceModels.get(last) instanceof NewtonianAttraction;
  247.     }

  249.     /** Add a force model to the global perturbation model.
  250.      * <p>If this method is not called at all, the integrated orbit will follow
  251.      * a Keplerian evolution only.</p>
  252.      * @param model perturbing {@link ForceModel} to add
  253.      * @see #removeForceModels()
  254.      * @see #setMu(CalculusFieldElement)
  255.      */
  256.     public void addForceModel(final ForceModel model) {

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

  261.             try {
  262.                 // ensure we are notified of any mu change
  263.                 model.getParametersDrivers().get(0).addObserver(new ParameterObserver() {
  264.                     /** {@inheritDoc} */
  265.                     @Override
  266.                     public void valueChanged(final double previousValue, final ParameterDriver driver) {
  267.                         superSetMu(field.getZero().add(driver.getValue()));
  268.                     }
  269.                 });
  270.             } catch (OrekitException oe) {
  271.                 // this should never happen
  272.                 throw new OrekitInternalError(oe);
  273.             }

  275.             if (hasNewtonianAttraction()) {
  276.                 // there is already a central attraction model, replace it
  277.                 forceModels.set(forceModels.size() - 1, model);
  278.             } else {
  279.                 // there are no central attraction model yet, add it at the end of the list
  280.                 forceModels.add(model);
  281.             }
  282.         } else {
  283.             // we want to add a perturbing force model
  284.             if (hasNewtonianAttraction()) {
  285.                 // insert the new force model before Newtonian attraction,
  286.                 // which should always be the last one in the list
  287.                 forceModels.add(forceModels.size() - 1, model);
  288.             } else {
  289.                 // we only have perturbing force models up to now, just append at the end of the list
  290.                 forceModels.add(model);
  291.             }
  292.         }

  294.     }

  296.     /** Remove all perturbing force models from the global perturbation model.
  297.      * <p>Once all perturbing forces have been removed (and as long as no new force
  298.      * model is added), the integrated orbit will follow a Keplerian evolution
  299.      * only.</p>
  300.      * @see #addForceModel(ForceModel)
  301.      */
  302.     public void removeForceModels() {
  303.         forceModels.clear();
  304.     }

  306.     /** Get all the force models, perturbing forces and Newtonian attraction included.
  307.      * @return list of perturbing force models, with Newtonian attraction being the
  308.      * last one
  309.      * @see #addForceModel(ForceModel)
  310.      * @see #setMu(CalculusFieldElement)
  311.      * @since 9.1
  312.      */
  313.     public List<ForceModel> getAllForceModels() {
  314.         return Collections.unmodifiableList(forceModels);
  315.     }

  317.     /** Set propagation orbit type.
  318.      * @param orbitType orbit type to use for propagation
  319.      */
  320.     public void setOrbitType(final OrbitType orbitType) {
  321.         super.setOrbitType(orbitType);
  322.     }

  324.     /** Get propagation parameter type.
  325.      * @return orbit type used for propagation
  326.      */
  327.     public OrbitType getOrbitType() {
  328.         return superGetOrbitType();
  329.     }

  331.     /** Get propagation parameter type.
  332.      * @return orbit type used for propagation
  333.      */
  334.     private OrbitType superGetOrbitType() {
  335.         return super.getOrbitType();
  336.     }

  338.     /** Set position angle type.
  339.      * <p>
  340.      * The position parameter type is meaningful only if {@link
  341.      * #getOrbitType() propagation orbit type}
  342.      * support it. As an example, it is not meaningful for propagation
  343.      * in {@link OrbitType#CARTESIAN Cartesian} parameters.
  344.      * </p>
  345.      * @param positionAngleType angle type to use for propagation
  346.      */
  347.     public void setPositionAngleType(final PositionAngle positionAngleType) {
  348.         super.setPositionAngleType(positionAngleType);
  349.     }

  351.     /** Get propagation parameter type.
  352.      * @return angle type to use for propagation
  353.      */
  354.     public PositionAngle getPositionAngleType() {
  355.         return super.getPositionAngleType();
  356.     }

  358.     /** Set the initial state.
  359.      * @param initialState initial state
  360.      */
  361.     public void setInitialState(final FieldSpacecraftState<T> initialState) {
  362.         resetInitialState(initialState);
  363.     }

  365.     /** {@inheritDoc} */
  366.     public void resetInitialState(final FieldSpacecraftState<T> state) {
  367.         super.resetInitialState(state);
  368.         if (!hasNewtonianAttraction()) {
  369.             setMu(state.getMu());
  370.         }
  371.         setStartDate(state.getDate());
  372.     }

  374.     /** {@inheritDoc} */
  375.     public TimeStampedFieldPVCoordinates<T> getPVCoordinates(final FieldAbsoluteDate<T> date, final Frame frame) {
  376.         return propagate(date).getPVCoordinates(frame);
  377.     }

  379.     /** {@inheritDoc} */
  380.     protected FieldStateMapper<T> createMapper(final FieldAbsoluteDate<T> referenceDate, final T mu,
  381.                                        final OrbitType orbitType, final PositionAngle positionAngleType,
  382.                                        final AttitudeProvider attitudeProvider, final Frame frame) {
  383.         return new FieldOsculatingMapper(referenceDate, mu, orbitType, positionAngleType, attitudeProvider, frame);
  384.     }

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

  389.         /** Simple constructor.
  390.          * <p>
  391.          * The position parameter type is meaningful only if {@link
  392.          * #getOrbitType() propagation orbit type}
  393.          * support it. As an example, it is not meaningful for propagation
  394.          * in {@link OrbitType#CARTESIAN Cartesian} parameters.
  395.          * </p>
  396.          * @param referenceDate reference date
  397.          * @param mu central attraction coefficient (m³/s²)
  398.          * @param orbitType orbit type to use for mapping
  399.          * @param positionAngleType angle type to use for propagation
  400.          * @param attitudeProvider attitude provider
  401.          * @param frame inertial frame
  402.          */
  403.         FieldOsculatingMapper(final FieldAbsoluteDate<T> referenceDate, final T mu,
  404.                               final OrbitType orbitType, final PositionAngle positionAngleType,
  405.                               final AttitudeProvider attitudeProvider, final Frame frame) {
  406.             super(referenceDate, mu, orbitType, positionAngleType, attitudeProvider, frame);
  407.         }

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

  414.             final T mass = y[6];
  415.             if (mass.getReal() <= 0.0) {
  416.                 throw new OrekitException(OrekitMessages.SPACECRAFT_MASS_BECOMES_NEGATIVE, mass);
  417.             }

  419.             if (superGetOrbitType() == null) {
  420.                 // propagation uses absolute position-velocity-acceleration
  421.                 final FieldVector3D<T> p = new FieldVector3D<>(y[0],    y[1],    y[2]);
  422.                 final FieldVector3D<T> v = new FieldVector3D<>(y[3],    y[4],    y[5]);
  423.                 final FieldVector3D<T> a;
  424.                 final FieldAbsolutePVCoordinates<T> absPva;
  425.                 if (yDot == null) {
  426.                     absPva = new FieldAbsolutePVCoordinates<>(getFrame(), new TimeStampedFieldPVCoordinates<>(date, p, v, FieldVector3D.getZero(date.getField())));
  427.                 } else {
  428.                     a = new FieldVector3D<>(yDot[3], yDot[4], yDot[5]);
  429.                     absPva = new FieldAbsolutePVCoordinates<>(getFrame(), new TimeStampedFieldPVCoordinates<>(date, p, v, a));
  430.                 }

  432.                 final FieldAttitude<T> attitude = getAttitudeProvider().getAttitude(absPva, date, getFrame());
  433.                 return new FieldSpacecraftState<>(absPva, attitude, mass);
  434.             } else {
  435.                 // propagation uses regular orbits
  436.                 final FieldOrbit<T> orbit       = superGetOrbitType().mapArrayToOrbit(y, yDot, super.getPositionAngleType(), date, getMu(), getFrame());
  437.                 final FieldAttitude<T> attitude = getAttitudeProvider().getAttitude(orbit, date, getFrame());
  438.                 return new FieldSpacecraftState<>(orbit, attitude, mass);
  439.             }
  440.         }

  442.         /** {@inheritDoc} */
  443.         public void mapStateToArray(final FieldSpacecraftState<T> state, final T[] y, final T[] yDot) {
  444.             if (superGetOrbitType() == null) {
  445.                 // propagation uses absolute position-velocity-acceleration
  446.                 final FieldVector3D<T> p = state.getAbsPVA().getPosition();
  447.                 final FieldVector3D<T> v = state.getAbsPVA().getVelocity();
  448.                 y[0] = p.getX();
  449.                 y[1] = p.getY();
  450.                 y[2] = p.getZ();
  451.                 y[3] = v.getX();
  452.                 y[4] = v.getY();
  453.                 y[5] = v.getZ();
  454.                 y[6] = state.getMass();
  455.             }
  456.             else {
  457.                 superGetOrbitType().mapOrbitToArray(state.getOrbit(), super.getPositionAngleType(), y, yDot);
  458.                 y[6] = state.getMass();
  459.             }
  460.         }

  462.     }

  464.     /** {@inheritDoc} */
  465.     protected MainStateEquations<T> getMainStateEquations(final FieldODEIntegrator<T> integrator) {
  466.         return new Main(integrator);
  467.     }

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

  472.         /** Derivatives array. */
  473.         private final T[] yDot;

  475.         /** Current state. */
  476.         private FieldSpacecraftState<T> currentState;

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

  481.         /** Simple constructor.
  482.          * @param integrator numerical integrator to use for propagation.
  483.          */
  484.         Main(final FieldODEIntegrator<T> integrator) {

  486.             this.yDot     = MathArrays.buildArray(getField(),  7);
  487.             this.jacobian = MathArrays.buildArray(getField(),  6, 6);
  488.             for (final ForceModel forceModel : forceModels) {
  489.                 forceModel.getFieldEventsDetectors(getField()).forEach(detector -> setUpEventDetector(integrator, detector));
  490.             }

  492.             if (superGetOrbitType() == null) {
  493.                 // propagation uses absolute position-velocity-acceleration
  494.                 // we can set Jacobian once and for all
  495.                 for (int i = 0; i < jacobian.length; ++i) {
  496.                     Arrays.fill(jacobian[i], getField().getZero());
  497.                     jacobian[i][i] = getField().getOne();
  498.                 }
  499.             }

  501.         }

  503.         /** {@inheritDoc} */
  504.         @Override
  505.         public void init(final FieldSpacecraftState<T> initialState, final FieldAbsoluteDate<T> target) {
  506.             forceModels.forEach(fm -> fm.init(initialState, target));
  507.         }

  509.         /** {@inheritDoc} */
  510.         @Override
  511.         public T[] computeDerivatives(final FieldSpacecraftState<T> state) {
  512.             final T zero = state.getA().getField().getZero();
  513.             currentState = state;
  514.             Arrays.fill(yDot, zero);
  515.             if (superGetOrbitType() != null) {
  516.                 // propagation uses regular orbits
  517.                 currentState.getOrbit().getJacobianWrtCartesian(getPositionAngleType(), jacobian);
  518.             }

  520.             // compute the contributions of all perturbing forces,
  521.             // using the Kepler contribution at the end since
  522.             // NewtonianAttraction is always the last instance in the list
  523.             for (final ForceModel forceModel : forceModels) {
  524.                 forceModel.addContribution(state, this);
  525.             }

  527.             if (superGetOrbitType() == null) {
  528.                 // position derivative is velocity, and was not added above in the force models
  529.                 // (it is added when orbit type is non-null because NewtonianAttraction considers it)
  530.                 final FieldVector3D<T> velocity = currentState.getPVCoordinates().getVelocity();
  531.                 yDot[0] = yDot[0].add(velocity.getX());
  532.                 yDot[1] = yDot[1].add(velocity.getY());
  533.                 yDot[2] = yDot[2].add(velocity.getZ());
  534.             }

  536.             return yDot.clone();

  538.         }

  540.         /** {@inheritDoc} */
  541.         @Override
  542.         public void addKeplerContribution(final T mu) {
  543.             if (superGetOrbitType() == null) {

  545.                 // if mu is neither 0 nor NaN, we want to include Newtonian acceleration
  546.                 if (mu.getReal() > 0) {
  547.                     // velocity derivative is Newtonian acceleration
  548.                     final FieldVector3D<T> position = currentState.getPVCoordinates().getPosition();
  549.                     final T r2         = position.getNormSq();
  550.                     final T coeff      = r2.multiply(r2.sqrt()).reciprocal().negate().multiply(mu);
  551.                     yDot[3] = yDot[3].add(coeff.multiply(position.getX()));
  552.                     yDot[4] = yDot[4].add(coeff.multiply(position.getY()));
  553.                     yDot[5] = yDot[5].add(coeff.multiply(position.getZ()));
  554.                 }

  556.             } else {
  557.                 // propagation uses regular orbits
  558.                 currentState.getOrbit().addKeplerContribution(getPositionAngleType(), mu, yDot);
  559.             }
  560.         }

  562.         /** {@inheritDoc} */
  563.         @Override
  564.         public void addNonKeplerianAcceleration(final FieldVector3D<T> gamma) {
  565.             for (int i = 0; i < 6; ++i) {
  566.                 final T[] jRow = jacobian[i];
  567.                 yDot[i] = yDot[i].add(jRow[3].linearCombination(jRow[3], gamma.getX(),
  568.                                                                 jRow[4], gamma.getY(),
  569.                                                                 jRow[5], gamma.getZ()));
  570.             }
  571.         }

  573.         /** {@inheritDoc} */
  574.         @Override
  575.         public void addMassDerivative(final T q) {
  576.             if (q.getReal() > 0) {
  577.                 throw new OrekitIllegalArgumentException(OrekitMessages.POSITIVE_FLOW_RATE, q);
  578.             }
  579.             yDot[6] = yDot[6].add(q);
  580.         }

  582.     }

  584.     /** Estimate tolerance vectors for integrators.
  585.      * <p>
  586.      * The errors are estimated from partial derivatives properties of orbits,
  587.      * starting from a scalar position error specified by the user.
  588.      * Considering the energy conservation equation V = sqrt(mu (2/r - 1/a)),
  589.      * we get at constant energy (i.e. on a Keplerian trajectory):
  590.      * <pre>
  591.      * V² r |dV| = mu |dr|
  592.      * </pre>
  593.      * So we deduce a scalar velocity error consistent with the position error.
  594.      * From here, we apply orbits Jacobians matrices to get consistent errors
  595.      * on orbital parameters.
  596.      * <p>
  597.      * The tolerances are only <em>orders of magnitude</em>, and integrator tolerances
  598.      * are only local estimates, not global ones. So some care must be taken when using
  599.      * these tolerances. Setting 1mm as a position error does NOT mean the tolerances
  600.      * will guarantee a 1mm error position after several orbits integration.
  601.      * </p>
  602.      * @param dP user specified position error
  603.      * @param orbit reference orbit
  604.      * @param type propagation type for the meaning of the tolerance vectors elements
  605.      * (it may be different from {@code orbit.getType()})
  606.      * @return a two rows array, row 0 being the absolute tolerance error and row 1
  607.      * being the relative tolerance error
  608.      * @param <T> elements type
  609.      */
  610.     public static <T extends CalculusFieldElement<T>> double[][] tolerances(final T dP, final FieldOrbit<T> orbit, final OrbitType type) {

  612.         // estimate the scalar velocity error
  613.         final FieldPVCoordinates<T> pv = orbit.getPVCoordinates();
  614.         final T r2 = pv.getPosition().getNormSq();
  615.         final T v  = pv.getVelocity().getNorm();
  616.         final T dV = dP.multiply(orbit.getMu()).divide(v.multiply(r2));

  618.         return tolerances(dP, dV, orbit, type);

  620.     }

  622.     /** Estimate tolerance vectors for integrators when propagating in orbits.
  623.      * <p>
  624.      * The errors are estimated from partial derivatives properties of orbits,
  625.      * starting from scalar position and velocity errors specified by the user.
  626.      * <p>
  627.      * The tolerances are only <em>orders of magnitude</em>, and integrator tolerances
  628.      * are only local estimates, not global ones. So some care must be taken when using
  629.      * these tolerances. Setting 1mm as a position error does NOT mean the tolerances
  630.      * will guarantee a 1mm error position after several orbits integration.
  631.      * </p>
  632.      * @param <T> elements type
  633.      * @param dP user specified position error
  634.      * @param dV user specified velocity error
  635.      * @param orbit reference orbit
  636.      * @param type propagation type for the meaning of the tolerance vectors elements
  637.      * (it may be different from {@code orbit.getType()})
  638.      * @return a two rows array, row 0 being the absolute tolerance error and row 1
  639.      * being the relative tolerance error
  640.      * @since 10.3
  641.      */
  642.     public static <T extends CalculusFieldElement<T>> double[][] tolerances(final T dP, final T dV,
  643.                                                                         final FieldOrbit<T> orbit, final OrbitType type) {

  645.         final double[] absTol = new double[7];
  646.         final double[] relTol = new double[7];

  648.         // we set the mass tolerance arbitrarily to 1.0e-6 kg, as mass evolves linearly
  649.         // with trust, this often has no influence at all on propagation
  650.         absTol[6] = 1.0e-6;

  652.         if (type == OrbitType.CARTESIAN) {
  653.             absTol[0] = dP.getReal();
  654.             absTol[1] = dP.getReal();
  655.             absTol[2] = dP.getReal();
  656.             absTol[3] = dV.getReal();
  657.             absTol[4] = dV.getReal();
  658.             absTol[5] = dV.getReal();
  659.         } else {

  661.             // convert the orbit to the desired type
  662.             final T[][] jacobian = MathArrays.buildArray(dP.getField(), 6, 6);
  663.             final FieldOrbit<T> converted = type.convertType(orbit);
  664.             converted.getJacobianWrtCartesian(PositionAngle.TRUE, jacobian);

  666.             for (int i = 0; i < 6; ++i) {
  667.                 final  T[] row = jacobian[i];
  668.                 absTol[i] =     row[0].abs().multiply(dP).
  669.                             add(row[1].abs().multiply(dP)).
  670.                             add(row[2].abs().multiply(dP)).
  671.                             add(row[3].abs().multiply(dV)).
  672.                             add(row[4].abs().multiply(dV)).
  673.                             add(row[5].abs().multiply(dV)).
  674.                             getReal();
  675.                 if (Double.isNaN(absTol[i])) {
  676.                     throw new OrekitException(OrekitMessages.SINGULAR_JACOBIAN_FOR_ORBIT_TYPE, type);
  677.                 }
  678.             }

  680.         }

  682.         Arrays.fill(relTol, dP.divide(orbit.getPVCoordinates().getPosition().getNormSq().sqrt()).getReal());

  684.         return new double[][] { absTol, relTol };

  686.     }

  688. }
Created with JaCoCo 0.8.7.202105040129