ClockOffsetHermiteInterpolator.java
/* Copyright 2002-2024 Thales Alenia Space
* Licensed to CS GROUP (CS) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* CS licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
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* See the License for the specific language governing permissions and
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*/
package org.orekit.time;
import org.hipparchus.analysis.interpolation.HermiteInterpolator;
import java.util.List;
/**bHermite interpolator of time stamped clock offsets.
* @author Luc Maisonobe
* @see HermiteInterpolator
* @see TimeInterpolator
* @since 12.1
*/
public class ClockOffsetHermiteInterpolator extends AbstractTimeInterpolator<ClockOffset> {
/**
* Constructor with default extrapolation threshold value ({@code DEFAULT_EXTRAPOLATION_THRESHOLD_SEC} s).
* <p>
* As this implementation of interpolation is polynomial, it should be used only with small number of interpolation
* points (about 10-20 points) in order to avoid <a href="http://en.wikipedia.org/wiki/Runge%27s_phenomenon">Runge's
* phenomenon</a> and numerical problems (including NaN appearing).
* </p>
* <p>
* If the number of interpolation points or derivatives availability is not sufficient,
* the rate and acceleration of interpolated offset will be silently set to 0 (i.e.
* model will be constant or linear only).
* </p>
* @param interpolationPoints number of interpolation points
*/
public ClockOffsetHermiteInterpolator(final int interpolationPoints) {
this(interpolationPoints, DEFAULT_EXTRAPOLATION_THRESHOLD_SEC);
}
/**
* Constructor.
* <p>
* As this implementation of interpolation is polynomial, it should be used only with small number of interpolation
* points (about 10-20 points) in order to avoid <a href="http://en.wikipedia.org/wiki/Runge%27s_phenomenon">Runge's
* phenomenon</a> and numerical problems (including NaN appearing).
* </p>
* <p>
* If the number of interpolation points or derivatives availability is not sufficient,
* the rate and acceleration of interpolated offset will be silently set to 0 (i.e.
* model will be constant or linear only).
* </p>
* @param interpolationPoints number of interpolation points
* @param extrapolationThreshold extrapolation threshold beyond which the propagation will fail
*/
public ClockOffsetHermiteInterpolator(final int interpolationPoints, final double extrapolationThreshold) {
super(interpolationPoints, extrapolationThreshold);
}
/** {@inheritDoc} */
@Override
protected ClockOffset interpolate(final InterpolationData interpolationData) {
final HermiteInterpolator interpolator = new HermiteInterpolator();
// Fill interpolator with sample
final AbsoluteDate interpolationDate = interpolationData.getInterpolationDate();
final List<ClockOffset> neighborList = interpolationData.getNeighborList();
for (ClockOffset value : neighborList) {
final double deltaT = value.getDate().durationFrom(interpolationDate);
final double[] offset = new double[] { value.getOffset() };
if (Double.isNaN(value.getRate())) {
// no clock rate for this entry
interpolator.addSamplePoint(deltaT, offset);
} else {
// clock rate is available
final double[] rate = new double[] { value.getRate() };
if (Double.isNaN(value.getAcceleration())) {
// no clock acceleration for this entry
interpolator.addSamplePoint(deltaT, offset, rate);
} else {
// clock acceleration is available
final double[] acceleration = new double[] { value.getAcceleration() };
interpolator.addSamplePoint(deltaT, offset, rate, acceleration);
}
}
}
final double[][] y = interpolator.derivatives(0, 2);
return new ClockOffset(interpolationDate, y[0][0], y[1][0], y[2][0]);
}
}