AbstractMatricesHarvester.java
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* CS licenses this file to You under the Apache License, Version 2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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package org.orekit.propagation;
import java.util.List;
import org.hipparchus.linear.MatrixUtils;
import org.hipparchus.linear.RealMatrix;
import org.orekit.orbits.PositionAngleType;
import org.orekit.utils.DoubleArrayDictionary;
/** Base harvester between two-dimensional Jacobian matrices and one-dimensional {@link
* SpacecraftState#getAdditionalState(String) additional state arrays}.
* @author Luc Maisonobe
* @since 11.1
*/
public abstract class AbstractMatricesHarvester implements MatricesHarvester {
/** State dimension, fixed to 6. */
public static final int STATE_DIMENSION = 6;
/** Identity conversion matrix. */
private static final double[][] IDENTITY = {
{ 1.0, 0.0, 0.0, 0.0, 0.0, 0.0 },
{ 0.0, 1.0, 0.0, 0.0, 0.0, 0.0 },
{ 0.0, 0.0, 1.0, 0.0, 0.0, 0.0 },
{ 0.0, 0.0, 0.0, 1.0, 0.0, 0.0 },
{ 0.0, 0.0, 0.0, 0.0, 1.0, 0.0 },
{ 0.0, 0.0, 0.0, 0.0, 0.0, 1.0 }
};
/** Initial State Transition Matrix. */
private final RealMatrix initialStm;
/** Initial columns of the Jacobians matrix with respect to parameters. */
private final DoubleArrayDictionary initialJacobianColumns;
/** State Transition Matrix state name. */
private final String stmName;
/** Simple constructor.
* <p>
* The arguments for initial matrices <em>must</em> be compatible with the {@link org.orekit.orbits.OrbitType orbit type}
* and {@link PositionAngleType position angle} that will be used by propagator
* </p>
* @param stmName State Transition Matrix state name
* @param initialStm initial State Transition Matrix ∂Y/∂Y₀,
* if null (which is the most frequent case), assumed to be 6x6 identity
* @param initialJacobianColumns initial columns of the Jacobians matrix with respect to parameters,
* if null or if some selected parameters are missing from the dictionary, the corresponding
* initial column is assumed to be 0
*/
protected AbstractMatricesHarvester(final String stmName, final RealMatrix initialStm, final DoubleArrayDictionary initialJacobianColumns) {
this.stmName = stmName;
this.initialStm = initialStm == null ? MatrixUtils.createRealIdentityMatrix(STATE_DIMENSION) : initialStm;
this.initialJacobianColumns = initialJacobianColumns == null ? new DoubleArrayDictionary() : initialJacobianColumns;
}
/** Get the State Transition Matrix state name.
* @return State Transition Matrix state name
*/
public String getStmName() {
return stmName;
}
/** Get the initial State Transition Matrix.
* @return initial State Transition Matrix
*/
public RealMatrix getInitialStateTransitionMatrix() {
return initialStm;
}
/** Get the initial column of Jacobian matrix with respect to named parameter.
* @param columnName name of the column
* @return initial column of the Jacobian matrix
*/
public double[] getInitialJacobianColumn(final String columnName) {
final DoubleArrayDictionary.Entry entry = initialJacobianColumns.getEntry(columnName);
return entry == null ? new double[STATE_DIMENSION] : entry.getValue();
}
/** Get the conversion Jacobian between state parameters and parameters used for derivatives.
* <p>
* The base implementation returns identity, which is suitable for DSST and TLE propagators,
* as state parameters and parameters used for derivatives are the same.
* </p>
* <p>
* For Numerical propagator, parameters used for derivatives are Cartesian
* and they can be different from state parameters because the numerical propagator can accept different type
* of orbits, so the method is overridden in derived classes.
* </p>
* @param state spacecraft state
* @return conversion Jacobian
*/
protected double[][] getConversionJacobian(final SpacecraftState state) {
return IDENTITY;
}
/** {@inheritDoc} */
@Override
public void setReferenceState(final SpacecraftState reference) {
// nothing to do
}
/** {@inheritDoc} */
@Override
public RealMatrix getStateTransitionMatrix(final SpacecraftState state) {
if (!state.hasAdditionalState(stmName)) {
return null;
}
// get the conversion Jacobian
final double[][] dYdC = getConversionJacobian(state);
// extract the additional state
final double[] p = state.getAdditionalState(stmName);
// compute dYdY0 = dYdC * dCdY0
final RealMatrix dYdY0 = MatrixUtils.createRealMatrix(STATE_DIMENSION, STATE_DIMENSION);
for (int i = 0; i < STATE_DIMENSION; i++) {
final double[] rowC = dYdC[i];
for (int j = 0; j < STATE_DIMENSION; ++j) {
double sum = 0;
int pIndex = j;
for (int k = 0; k < STATE_DIMENSION; ++k) {
sum += rowC[k] * p[pIndex];
pIndex += STATE_DIMENSION;
}
dYdY0.setEntry(i, j, sum);
}
}
return dYdY0;
}
/** {@inheritDoc} */
@Override
public RealMatrix getParametersJacobian(final SpacecraftState state) {
final List<String> columnsNames = getJacobiansColumnsNames();
if (columnsNames == null || columnsNames.isEmpty()) {
return null;
}
// get the conversion Jacobian
final double[][] dYdC = getConversionJacobian(state);
// compute dYdP = dYdC * dCdP
final RealMatrix dYdP = MatrixUtils.createRealMatrix(STATE_DIMENSION, columnsNames.size());
for (int j = 0; j < columnsNames.size(); j++) {
final double[] p = state.getAdditionalState(columnsNames.get(j));
for (int i = 0; i < STATE_DIMENSION; ++i) {
final double[] dYdCi = dYdC[i];
double sum = 0;
for (int k = 0; k < STATE_DIMENSION; ++k) {
sum += dYdCi[k] * p[k];
}
dYdP.setEntry(i, j, sum);
}
}
return dYdP;
}
/** Freeze the names of the Jacobian columns.
* <p>
* This method is called when propagation starts, i.e. when configuration is completed
* </p>
*/
public abstract void freezeColumnsNames();
}