AbstractGradientConverter.java
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* this work for additional information regarding copyright ownership.
* CS licenses this file to You under the Apache License, Version 2.0
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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.analysis.differentiation.Gradient;
import org.hipparchus.geometry.euclidean.threed.FieldRotation;
import org.hipparchus.geometry.euclidean.threed.FieldVector3D;
import org.orekit.attitudes.FieldAttitude;
import org.orekit.orbits.FieldCartesianOrbit;
import org.orekit.orbits.FieldOrbit;
import org.orekit.propagation.FieldSpacecraftState;
import org.orekit.utils.FieldAngularCoordinates;
import org.orekit.utils.FieldPVCoordinates;
import org.orekit.utils.ParameterDriver;
import org.orekit.utils.ParametersDriversProvider;
import org.orekit.utils.TimeStampedFieldAngularCoordinates;
import org.orekit.utils.TimeStampedFieldPVCoordinates;
/** 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 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);
}
/**
* 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 ParametersDriversProvider parametricModel) {
// count the required number of parameters
int nbParams = 0;
for (final ParameterDriver driver : parametricModel.getParametersDrivers()) {
if (driver.isSelected()) {
++nbParams;
}
}
// 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);
// orbit
final FieldPVCoordinates<Gradient> pv0 = s0.getPVCoordinates();
final FieldOrbit<Gradient> gOrbit =
new FieldCartesianOrbit<>(new TimeStampedFieldPVCoordinates<>(s0.getDate().toAbsoluteDate(),
extend(pv0.getPosition(), freeParameters),
extend(pv0.getVelocity(), freeParameters),
extend(pv0.getAcceleration(), freeParameters)),
s0.getFrame(), extend(s0.getMu(), freeParameters));
// attitude
final FieldAngularCoordinates<Gradient> ac0 = s0.getAttitude().getOrientation();
final FieldAttitude<Gradient> gAttitude =
new FieldAttitude<>(s0.getAttitude().getReferenceFrame(),
new TimeStampedFieldAngularCoordinates<>(gOrbit.getDate(),
extend(ac0.getRotation(), freeParameters),
extend(ac0.getRotationRate(), freeParameters),
extend(ac0.getRotationAcceleration(), freeParameters)));
// mass
final Gradient gM = extend(s0.getMass(), freeParameters);
gStates.set(nbParams, new FieldSpacecraftState<>(gOrbit, gAttitude, gM));
}
return gStates.get(nbParams);
}
/** Get the parametric model parameters.
* @param state state as returned by {@link #getState(ParametersDriversProvider) getState(parametricModel)}
* @param parametricModel parametric model associated with the parameters
* @return parametric model parameters
*/
public Gradient[] getParameters(final FieldSpacecraftState<Gradient> state,
final ParametersDriversProvider 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) {
parameters[i++] = driver.isSelected() ?
Gradient.variable(freeParameters, index++, driver.getValue()) :
Gradient.constant(freeParameters, driver.getValue());
}
return parameters;
}
}