DSSTJacobiansMapper.java
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package org.orekit.propagation.semianalytical.dsst;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import java.util.Map;
import org.hipparchus.analysis.differentiation.Gradient;
import org.orekit.errors.OrekitInternalError;
import org.orekit.propagation.FieldSpacecraftState;
import org.orekit.propagation.PropagationType;
import org.orekit.propagation.SpacecraftState;
import org.orekit.propagation.integration.AbstractJacobiansMapper;
import org.orekit.propagation.semianalytical.dsst.forces.DSSTForceModel;
import org.orekit.propagation.semianalytical.dsst.forces.FieldShortPeriodTerms;
import org.orekit.propagation.semianalytical.dsst.utilities.FieldAuxiliaryElements;
import org.orekit.utils.ParameterDriver;
import org.orekit.utils.ParameterDriversList;
/** Mapper between two-dimensional Jacobian matrices and one-dimensional {@link
* SpacecraftState#getAdditionalState(String) additional state arrays}.
* <p>
* This class does not hold the states by itself. Instances of this class are guaranteed
* to be immutable.
* </p>
* @author Luc Maisonobe
* @author Bryan Cazabonne
* @see org.orekit.propagation.semianalytical.dsst.DSSTPartialDerivativesEquations
* @see org.orekit.propagation.semianalytical.dsst.DSSTPropagator
* @see SpacecraftState#getAdditionalState(String)
* @see org.orekit.propagation.AbstractPropagator
*/
public class DSSTJacobiansMapper extends AbstractJacobiansMapper {
/** State dimension, fixed to 6.
* @since 9.0
*/
public static final int STATE_DIMENSION = 6;
/** Retrograde factor I.
* <p>
* DSST model needs equinoctial orbit as internal representation.
* Classical equinoctial elements have discontinuities when inclination
* is close to zero. In this representation, I = +1. <br>
* To avoid this discontinuity, another representation exists and equinoctial
* elements can be expressed in a different way, called "retrograde" orbit.
* This implies I = -1. <br>
* As Orekit doesn't implement the retrograde orbit, I is always set to +1.
* But for the sake of consistency with the theory, the retrograde factor
* has been kept in the formulas.
* </p>
*/
private static final int I = 1;
/** Name. */
private String name;
/** Selected parameters for Jacobian computation. */
private final ParameterDriversList parameters;
/** Parameters map. */
private Map<ParameterDriver, Integer> map;
/** Propagator computing state evolution. */
private final DSSTPropagator propagator;
/** Placeholder for the derivatives of the short period terms.*/
private double[] shortPeriodDerivatives;
/** Type of the orbit used for the propagation.*/
private PropagationType propagationType;
/** Simple constructor.
* @param name name of the Jacobians
* @param parameters selected parameters for Jacobian computation
* @param propagator the propagator that will handle the orbit propagation
* @param map parameters map
* @param propagationType type of the orbit used for the propagation (mean or osculating)
*/
DSSTJacobiansMapper(final String name,
final ParameterDriversList parameters,
final DSSTPropagator propagator,
final Map<ParameterDriver, Integer> map,
final PropagationType propagationType) {
super(name, parameters);
shortPeriodDerivatives = null;
this.parameters = parameters;
this.name = name;
this.propagator = propagator;
this.map = map;
this.propagationType = propagationType;
}
/** {@inheritDoc} */
public void setInitialJacobians(final SpacecraftState state, final double[][] dY1dY0,
final double[][] dY1dP, final double[] p) {
// map the converted state Jacobian to one-dimensional array
int index = 0;
for (int i = 0; i < STATE_DIMENSION; ++i) {
for (int j = 0; j < STATE_DIMENSION; ++j) {
p[index++] = (i == j) ? 1.0 : 0.0;
}
}
if (parameters.getNbParams() != 0) {
// map the converted parameters Jacobian to one-dimensional array
for (int i = 0; i < STATE_DIMENSION; ++i) {
for (int j = 0; j < parameters.getNbParams(); ++j) {
p[index++] = dY1dP[i][j];
}
}
}
}
/** {@inheritDoc} */
public void getStateJacobian(final SpacecraftState state, final double[][] dYdY0) {
// extract additional state
final double[] p = state.getAdditionalState(name);
for (int i = 0; i < STATE_DIMENSION; i++) {
final double[] row = dYdY0[i];
for (int j = 0; j < STATE_DIMENSION; j++) {
row[j] = p[i * STATE_DIMENSION + j] + shortPeriodDerivatives[i * STATE_DIMENSION + j];
}
}
}
/** {@inheritDoc} */
public void getParametersJacobian(final SpacecraftState state, final double[][] dYdP) {
if (parameters.getNbParams() != 0) {
// extract the additional state
final double[] p = state.getAdditionalState(name);
for (int i = 0; i < STATE_DIMENSION; i++) {
final double[] row = dYdP[i];
for (int j = 0; j < parameters.getNbParams(); j++) {
row[j] = p[STATE_DIMENSION * STATE_DIMENSION + (j + parameters.getNbParams() * i)] +
shortPeriodDerivatives[STATE_DIMENSION * STATE_DIMENSION + (j + parameters.getNbParams() * i)];
}
}
}
}
/** Compute the derivatives of the short period terms related to the additional state parameters.
* @param s Current state information: date, kinematics, attitude, and additional state
*/
@SuppressWarnings("unchecked")
public void setShortPeriodJacobians(final SpacecraftState s) {
final double[] p = s.getAdditionalState(name);
if (shortPeriodDerivatives == null) {
shortPeriodDerivatives = new double[p.length];
}
switch (propagationType) {
case MEAN :
break;
case OSCULATING :
// initialize Jacobians to zero
final int paramDim = parameters.getNbParams();
final int dim = 6;
final double[][] dShortPerioddState = new double[dim][dim];
final double[][] dShortPerioddParam = new double[dim][paramDim];
final DSSTGradientConverter converter = new DSSTGradientConverter(s, propagator.getAttitudeProvider());
// Compute Jacobian
for (final DSSTForceModel forceModel : propagator.getAllForceModels()) {
final FieldSpacecraftState<Gradient> dsState = converter.getState(forceModel);
final Gradient[] dsParameters = converter.getParameters(dsState, forceModel);
final FieldAuxiliaryElements<Gradient> auxiliaryElements = new FieldAuxiliaryElements<>(dsState.getOrbit(), I);
final Gradient zero = dsState.getDate().getField().getZero();
final List<FieldShortPeriodTerms<Gradient>> shortPeriodTerms = new ArrayList<>();
shortPeriodTerms.addAll(forceModel.initializeShortPeriodTerms(auxiliaryElements, propagationType, dsParameters));
forceModel.updateShortPeriodTerms(dsParameters, dsState);
final Gradient[] shortPeriod = new Gradient[6];
Arrays.fill(shortPeriod, zero);
for (final FieldShortPeriodTerms<Gradient> spt : shortPeriodTerms) {
final Gradient[] spVariation = spt.value(dsState.getOrbit());
for (int i = 0; i < spVariation .length; i++) {
shortPeriod[i] = shortPeriod[i].add(spVariation[i]);
}
}
final double[] derivativesASP = shortPeriod[0].getGradient();
final double[] derivativesExSP = shortPeriod[1].getGradient();
final double[] derivativesEySP = shortPeriod[2].getGradient();
final double[] derivativesHxSP = shortPeriod[3].getGradient();
final double[] derivativesHySP = shortPeriod[4].getGradient();
final double[] derivativesLSP = shortPeriod[5].getGradient();
// update Jacobian with respect to state
addToRow(derivativesASP, 0, dShortPerioddState);
addToRow(derivativesExSP, 1, dShortPerioddState);
addToRow(derivativesEySP, 2, dShortPerioddState);
addToRow(derivativesHxSP, 3, dShortPerioddState);
addToRow(derivativesHySP, 4, dShortPerioddState);
addToRow(derivativesLSP, 5, dShortPerioddState);
int index = converter.getFreeStateParameters();
for (ParameterDriver driver : forceModel.getParametersDrivers()) {
if (driver.isSelected()) {
final int parameterIndex = map.get(driver);
dShortPerioddParam[0][parameterIndex] += derivativesASP[index];
dShortPerioddParam[1][parameterIndex] += derivativesExSP[index];
dShortPerioddParam[2][parameterIndex] += derivativesEySP[index];
dShortPerioddParam[3][parameterIndex] += derivativesHxSP[index];
dShortPerioddParam[4][parameterIndex] += derivativesHySP[index];
dShortPerioddParam[5][parameterIndex] += derivativesLSP[index];
++index;
}
}
}
// Get orbital short period derivatives with respect orbital elements.
for (int i = 0; i < dim; i++) {
for (int j = 0; j < dim; j++) {
shortPeriodDerivatives[j + dim * i] = dShortPerioddState[i][j];
}
}
// Get orbital short period derivatives with respect to model parameters.
final int columnTop = dim * dim;
for (int k = 0; k < paramDim; k++) {
for (int i = 0; i < dim; ++i) {
shortPeriodDerivatives[columnTop + (i + dim * k)] = dShortPerioddParam[i][k];
}
}
break;
default:
throw new OrekitInternalError(null);
}
}
/** Fill Jacobians rows.
* @param derivatives derivatives of a component
* @param index component index (0 for a, 1 for ex, 2 for ey, 3 for hx, 4 for hy, 5 for l)
* @param dMeanElementRatedElement Jacobian of mean elements rate with respect to mean elements
*/
private void addToRow(final double[] derivatives, final int index,
final double[][] dMeanElementRatedElement) {
for (int i = 0; i < 6; i++) {
dMeanElementRatedElement[index][i] += derivatives[i];
}
}
}