AbstractGradientConverter.java
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* this work for additional information regarding copyright ownership.
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*
* http://www.apache.org/licenses/LICENSE-2.0
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* Unless required by applicable law or agreed to in writing, software
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package org.orekit.propagation.integration;
import java.util.ArrayList;
import java.util.List;
import org.hipparchus.Field;
import org.hipparchus.analysis.differentiation.Gradient;
import org.hipparchus.analysis.differentiation.GradientField;
import org.hipparchus.geometry.euclidean.threed.FieldRotation;
import org.hipparchus.geometry.euclidean.threed.FieldVector3D;
import org.hipparchus.geometry.euclidean.threed.Vector3D;
import org.orekit.attitudes.AttitudeProvider;
import org.orekit.attitudes.FieldAttitude;
import org.orekit.orbits.FieldCartesianOrbit;
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.time.AbsoluteDate;
import org.orekit.time.FieldAbsoluteDate;
import org.orekit.utils.FieldAngularCoordinates;
import org.orekit.utils.FieldPVCoordinates;
import org.orekit.utils.FieldAbsolutePVCoordinates;
import org.orekit.utils.ParameterDriver;
import org.orekit.utils.ParameterDriversProvider;
import org.orekit.utils.TimeStampedFieldAngularCoordinates;
import org.orekit.utils.TimeStampedFieldPVCoordinates;
import org.orekit.utils.TimeSpanMap.Span;
/** Converter for states and parameters arrays.
* @author Luc Maisonobe
* @author Bryan Cazabonne
* @since 10.2
*/
public abstract class AbstractGradientConverter {
/** Dimension of the state. */
private final int freeStateParameters;
/** States with various number of additional parameters. */
private final List<FieldSpacecraftState<Gradient>> gStates;
/** Simple constructor.
* @param freeStateParameters number of free parameters
*/
protected AbstractGradientConverter(final int freeStateParameters) {
this.freeStateParameters = freeStateParameters;
this.gStates = new ArrayList<>();
}
/** Get the number of free state parameters.
* @return number of free state parameters
*/
public int getFreeStateParameters() {
return freeStateParameters;
}
/** Initialize first state with 0 parameters.
* @param zeroParametersState state with zero parameters
* @since 11.2
*/
protected void initStates(final FieldSpacecraftState<Gradient> zeroParametersState) {
gStates.clear();
gStates.add(zeroParametersState);
}
/** Add zero derivatives.
* @param original original scalar
* @param freeParameters total number of free parameters in the gradient
* @return extended scalar
*/
protected Gradient extend(final Gradient original, final int freeParameters) {
final double[] originalDerivatives = original.getGradient();
final double[] extendedDerivatives = new double[freeParameters];
System.arraycopy(originalDerivatives, 0, extendedDerivatives, 0, originalDerivatives.length);
return new Gradient(original.getValue(), extendedDerivatives);
}
/**
* Add zero derivatives.
*
* @param original original date
* @param freeParameters total number of free parameters in the gradient
* @return extended date
*/
protected FieldAbsoluteDate<Gradient> extend(
final FieldAbsoluteDate<Gradient> original,
final int freeParameters) {
final AbsoluteDate date = original.toAbsoluteDate();
final Gradient gradient = original.durationFrom(date);
return new FieldAbsoluteDate<>(date, extend(gradient, freeParameters));
}
/** Add zero derivatives.
* @param original original vector
* @param freeParameters total number of free parameters in the gradient
* @return extended vector
*/
protected FieldVector3D<Gradient> extend(final FieldVector3D<Gradient> original, final int freeParameters) {
return new FieldVector3D<>(extend(original.getX(), freeParameters),
extend(original.getY(), freeParameters),
extend(original.getZ(), freeParameters));
}
/** Add zero derivatives.
* @param original original rotation
* @param freeParameters total number of free parameters in the gradient
* @return extended rotation
*/
protected FieldRotation<Gradient> extend(final FieldRotation<Gradient> original, final int freeParameters) {
return new FieldRotation<>(extend(original.getQ0(), freeParameters),
extend(original.getQ1(), freeParameters),
extend(original.getQ2(), freeParameters),
extend(original.getQ3(), freeParameters),
false);
}
/** Process a state into a Gradient version without force model parameter.
* @param state state
* @param freeStateParameters number of free parameters
* @param provider attitude provider
* @return Gradient version of the state
* @since 12.0
*/
protected static FieldSpacecraftState<Gradient> buildBasicGradientSpacecraftState(final SpacecraftState state,
final int freeStateParameters,
final AttitudeProvider provider) {
// Derivative field
final Field<Gradient> field = GradientField.getField(freeStateParameters);
// position always has derivatives
final Vector3D pos = state.getPosition();
final FieldVector3D<Gradient> posG = new FieldVector3D<>(
Gradient.variable(freeStateParameters, 0, pos.getX()),
Gradient.variable(freeStateParameters, 1, pos.getY()),
Gradient.variable(freeStateParameters, 2, pos.getZ()));
// velocity may have derivatives or not
final Vector3D vel = state.getPVCoordinates().getVelocity();
final FieldVector3D<Gradient> velG;
if (freeStateParameters > 3) {
velG = new FieldVector3D<>(
Gradient.variable(freeStateParameters, 3, vel.getX()),
Gradient.variable(freeStateParameters, 4, vel.getY()),
Gradient.variable(freeStateParameters, 5, vel.getZ()));
} else {
velG = new FieldVector3D<>(field, vel);
}
// acceleration never has derivatives
final Vector3D acc = state.getPVCoordinates().getAcceleration();
final FieldVector3D<Gradient> accG = new FieldVector3D<>(field, acc);
// mass never has derivatives
final Gradient gMass = Gradient.constant(freeStateParameters, state.getMass());
final TimeStampedFieldPVCoordinates<Gradient> timeStampedFieldPVCoordinates = new TimeStampedFieldPVCoordinates<>(
state.getDate(), posG, velG, accG);
final FieldCartesianOrbit<Gradient> gOrbit;
final FieldAbsolutePVCoordinates<Gradient> gAbsolutePV;
if (state.isOrbitDefined()) {
final Gradient gMu = Gradient.constant(freeStateParameters, state.getMu());
gOrbit = new FieldCartesianOrbit<>(timeStampedFieldPVCoordinates, state.getFrame(), gMu);
gAbsolutePV = null;
} else {
gOrbit = null;
gAbsolutePV = new FieldAbsolutePVCoordinates<>(state.getFrame(), timeStampedFieldPVCoordinates);
}
final FieldAttitude<Gradient> gAttitude;
if (freeStateParameters > 3) {
// compute attitude partial derivatives with respect to position/velocity
gAttitude = provider.getAttitude((state.isOrbitDefined()) ? gOrbit : gAbsolutePV,
timeStampedFieldPVCoordinates.getDate(), state.getFrame());
} else {
// force model does not depend on attitude, don't bother recomputing it
gAttitude = new FieldAttitude<>(field, state.getAttitude());
}
if (state.isOrbitDefined()) {
return new FieldSpacecraftState<>(gOrbit, gAttitude, gMass);
} else {
return new FieldSpacecraftState<>(gAbsolutePV, gAttitude, gMass);
}
}
/**
* Get the state with the number of parameters consistent with parametric model.
* @param parametricModel parametric model
* @return state with the number of parameters consistent with parametric model
*/
public FieldSpacecraftState<Gradient> getState(final ParameterDriversProvider parametricModel) {
// count the required number of parameters
int nbParams = 0;
for (final ParameterDriver driver : parametricModel.getParametersDrivers()) {
if (driver.isSelected()) {
nbParams += driver.getNbOfValues();
}
}
// fill in intermediate slots
while (gStates.size() < nbParams + 1) {
gStates.add(null);
}
if (gStates.get(nbParams) == null) {
// it is the first time we need this number of parameters
// we need to create the state
final int freeParameters = freeStateParameters + nbParams;
final FieldSpacecraftState<Gradient> s0 = gStates.get(0);
final AbsoluteDate date = s0.getDate().toAbsoluteDate();
// attitude
final FieldAngularCoordinates<Gradient> ac0 = s0.getAttitude().getOrientation();
final FieldAttitude<Gradient> gAttitude =
new FieldAttitude<>(s0.getAttitude().getReferenceFrame(),
new TimeStampedFieldAngularCoordinates<>(date,
extend(ac0.getRotation(), freeParameters),
extend(ac0.getRotationRate(), freeParameters),
extend(ac0.getRotationAcceleration(), freeParameters)));
// mass
final Gradient gMass = extend(s0.getMass(), freeParameters);
// orbit or absolute position-velocity coordinates
final FieldPVCoordinates<Gradient> pv0 = s0.getPVCoordinates();
final TimeStampedFieldPVCoordinates<Gradient> timeStampedFieldPVCoordinates = new TimeStampedFieldPVCoordinates<>(
date,
extend(pv0.getPosition(), freeParameters),
extend(pv0.getVelocity(), freeParameters),
extend(pv0.getAcceleration(), freeParameters));
final FieldSpacecraftState<Gradient> spacecraftState;
if (s0.isOrbitDefined()) {
final FieldOrbit<Gradient> orbit = s0.getOrbit();
if (orbit instanceof FieldEquinoctialOrbit) {
// for DSST, which always uses EquinoctialOrbit, not CartesianOrbit
// wish there was a way to do this without casting...
final FieldEquinoctialOrbit<Gradient> equinoctialOrbit =
(FieldEquinoctialOrbit<Gradient>) orbit;
final PositionAngleType angleType =
equinoctialOrbit.getCachedPositionAngleType();
spacecraftState = new FieldSpacecraftState<>(
new FieldEquinoctialOrbit<>(
extend(equinoctialOrbit.getA(), freeParameters),
extend(equinoctialOrbit.getEquinoctialEx(), freeParameters),
extend(equinoctialOrbit.getEquinoctialEy(), freeParameters),
extend(equinoctialOrbit.getHx(), freeParameters),
extend(equinoctialOrbit.getHy(), freeParameters),
extend(equinoctialOrbit.getL(angleType), freeParameters),
angleType,
s0.getFrame(),
extend(s0.getDate(), freeParameters),
extend(s0.getMu(), freeParameters)
),
gAttitude,
gMass);
} else {
spacecraftState = new FieldSpacecraftState<>(new FieldCartesianOrbit<>(timeStampedFieldPVCoordinates,
s0.getFrame(), extend(s0.getMu(), freeParameters)), gAttitude, gMass);
}
} else {
spacecraftState = new FieldSpacecraftState<>(new FieldAbsolutePVCoordinates<>(s0.getFrame(),
timeStampedFieldPVCoordinates), gAttitude, gMass);
}
gStates.set(nbParams, spacecraftState);
}
return gStates.get(nbParams);
}
/** Get the parametric model parameters, return gradient values for each span of each driver (several gradient
* values for each parameter).
* Different from {@link #getParametersAtStateDate(FieldSpacecraftState, ParameterDriversProvider)}
* which return a Gradient list containing for each driver the gradient value at state date (only 1 gradient
* value for each parameter).
* @param state state as returned by {@link #getState(ParameterDriversProvider) getState(parametricModel)}
* @param parametricModel parametric model associated with the parameters
* @return parametric model parameters (for all span of each driver)
*/
public Gradient[] getParameters(final FieldSpacecraftState<Gradient> state,
final ParameterDriversProvider parametricModel) {
final int freeParameters = state.getMass().getFreeParameters();
final List<ParameterDriver> drivers = parametricModel.getParametersDrivers();
int sizeDrivers = 0;
for ( ParameterDriver driver : drivers) {
sizeDrivers += driver.getNbOfValues();
}
final Gradient[] parameters = new Gradient[sizeDrivers];
int index = freeStateParameters;
int i = 0;
for (ParameterDriver driver : drivers) {
// Loop on the spans
for (Span<Double> span = driver.getValueSpanMap().getFirstSpan(); span != null; span = span.next()) {
parameters[i++] = driver.isSelected() ?
Gradient.variable(freeParameters, index++, span.getData()) :
Gradient.constant(freeParameters, span.getData());
}
}
return parameters;
}
/** Get the parametric model parameters, return gradient values at state date for each driver (only 1 gradient
* value for each parameter).
* Different from {@link #getParameters(FieldSpacecraftState, ParameterDriversProvider)}
* which return a Gradient list containing for each driver the gradient values for each span value (several gradient
* values for each parameter).
* @param state state as returned by {@link #getState(ParameterDriversProvider) getState(parametricModel)}
* @param parametricModel parametric model associated with the parameters
* @return parametric model parameters (for all span of each driver)
*/
public Gradient[] getParametersAtStateDate(final FieldSpacecraftState<Gradient> state,
final ParameterDriversProvider parametricModel) {
final int freeParameters = state.getMass().getFreeParameters();
final List<ParameterDriver> drivers = parametricModel.getParametersDrivers();
final Gradient[] parameters = new Gradient[drivers.size()];
int index = freeStateParameters;
int i = 0;
for (ParameterDriver driver : drivers) {
for (Span<String> span = driver.getNamesSpanMap().getFirstSpan(); span != null; span = span.next()) {
if (span.getData().equals(driver.getNameSpan(state.getDate().toAbsoluteDate()))) {
parameters[i++] = driver.isSelected() ?
Gradient.variable(freeParameters, index, driver.getValue(state.getDate().toAbsoluteDate())) :
Gradient.constant(freeParameters, driver.getValue(state.getDate().toAbsoluteDate()));
}
index = driver.isSelected() ? index + 1 : index;
}
}
return parameters;
}
}