1 /* Copyright 2022-2026 Thales Alenia Space
2 * Licensed to CS GROUP (CS) under one or more
3 * contributor license agreements. See the NOTICE file distributed with
4 * this work for additional information regarding copyright ownership.
5 * CS licenses this file to You under the Apache License, Version 2.0
6 * (the "License"); you may not use this file except in compliance with
7 * the License. You may obtain a copy of the License at
8 *
9 * http://www.apache.org/licenses/LICENSE-2.0
10 *
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the License for the specific language governing permissions and
15 * limitations under the License.
16 */
17 package org.orekit.time.clocks;
18
19 import org.hipparchus.analysis.interpolation.HermiteInterpolator;
20 import org.orekit.time.AbsoluteDate;
21 import org.orekit.time.AbstractTimeInterpolator;
22 import org.orekit.time.TimeInterpolator;
23
24 import java.util.List;
25
26 /**bHermite interpolator of time stamped clock offsets.
27 * @author Luc Maisonobe
28 * @see HermiteInterpolator
29 * @see TimeInterpolator
30 * @since 12.1
31 */
32 public class ClockOffsetHermiteInterpolator extends AbstractTimeInterpolator<ClockOffset> {
33
34 /**
35 * Constructor with default extrapolation threshold value ({@code DEFAULT_EXTRAPOLATION_THRESHOLD_SEC} s).
36 * <p>
37 * As this implementation of interpolation is polynomial, it should be used only with small number of interpolation
38 * points (about 10-20 points) in order to avoid <a href="https://en.wikipedia.org/wiki/Runge%27s_phenomenon">Runge's
39 * phenomenon</a> and numerical problems (including NaN appearing).
40 * </p>
41 * <p>
42 * If the number of interpolation points or derivatives availability is not sufficient,
43 * the rate and acceleration of interpolated offset will be silently set to 0 (i.e.
44 * model will be constant or linear only).
45 * </p>
46 * @param interpolationPoints number of interpolation points
47 */
48 public ClockOffsetHermiteInterpolator(final int interpolationPoints) {
49 this(interpolationPoints, DEFAULT_EXTRAPOLATION_THRESHOLD_SEC);
50 }
51
52 /**
53 * Constructor.
54 * <p>
55 * As this implementation of interpolation is polynomial, it should be used only with small number of interpolation
56 * points (about 10-20 points) in order to avoid <a href="https://en.wikipedia.org/wiki/Runge%27s_phenomenon">Runge's
57 * phenomenon</a> and numerical problems (including NaN appearing).
58 * </p>
59 * <p>
60 * If the number of interpolation points or derivatives availability is not sufficient,
61 * the rate and acceleration of interpolated offset will be silently set to 0 (i.e.
62 * model will be constant or linear only).
63 * </p>
64 * @param interpolationPoints number of interpolation points
65 * @param extrapolationThreshold extrapolation threshold beyond which the propagation will fail
66 */
67 public ClockOffsetHermiteInterpolator(final int interpolationPoints, final double extrapolationThreshold) {
68 super(interpolationPoints, extrapolationThreshold);
69 }
70
71 /** {@inheritDoc} */
72 @Override
73 protected ClockOffset interpolate(final InterpolationData interpolationData) {
74 final HermiteInterpolator interpolator = new HermiteInterpolator();
75
76 // Fill interpolator with sample
77 final AbsoluteDate interpolationDate = interpolationData.getInterpolationDate();
78 final List<ClockOffset> neighborList = interpolationData.getNeighborList();
79 for (ClockOffset value : neighborList) {
80 final double deltaT = value.getDate().durationFrom(interpolationDate);
81 final double[] bias = new double[] { value.getBias() };
82 if (Double.isNaN(value.getRate())) {
83 // no clock rate for this entry
84 interpolator.addSamplePoint(deltaT, bias);
85 } else {
86 // clock rate is available
87 final double[] rate = new double[] { value.getRate() };
88 if (Double.isNaN(value.getAcceleration())) {
89 // no clock acceleration for this entry
90 interpolator.addSamplePoint(deltaT, bias, rate);
91 } else {
92 // clock acceleration is available
93 final double[] acceleration = new double[] { value.getAcceleration() };
94 interpolator.addSamplePoint(deltaT, bias, rate, acceleration);
95 }
96 }
97 }
98
99 final double[][] y = interpolator.derivatives(0, 2);
100 return new ClockOffset(interpolationDate, y[0][0], y[1][0], y[2][0]);
101
102 }
103
104 }