1 /* Copyright 2022-2025 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;
18
19 import org.hipparchus.analysis.interpolation.HermiteInterpolator;
20
21 import java.util.List;
22
23 /**bHermite interpolator of time stamped clock offsets.
24 * @author Luc Maisonobe
25 * @see HermiteInterpolator
26 * @see TimeInterpolator
27 * @since 12.1
28 */
29 public class ClockOffsetHermiteInterpolator extends AbstractTimeInterpolator<ClockOffset> {
30
31 /**
32 * Constructor with default extrapolation threshold value ({@code DEFAULT_EXTRAPOLATION_THRESHOLD_SEC} s).
33 * <p>
34 * As this implementation of interpolation is polynomial, it should be used only with small number of interpolation
35 * points (about 10-20 points) in order to avoid <a href="http://en.wikipedia.org/wiki/Runge%27s_phenomenon">Runge's
36 * phenomenon</a> and numerical problems (including NaN appearing).
37 * </p>
38 * <p>
39 * If the number of interpolation points or derivatives availability is not sufficient,
40 * the rate and acceleration of interpolated offset will be silently set to 0 (i.e.
41 * model will be constant or linear only).
42 * </p>
43 * @param interpolationPoints number of interpolation points
44 */
45 public ClockOffsetHermiteInterpolator(final int interpolationPoints) {
46 this(interpolationPoints, DEFAULT_EXTRAPOLATION_THRESHOLD_SEC);
47 }
48
49 /**
50 * Constructor.
51 * <p>
52 * As this implementation of interpolation is polynomial, it should be used only with small number of interpolation
53 * points (about 10-20 points) in order to avoid <a href="http://en.wikipedia.org/wiki/Runge%27s_phenomenon">Runge's
54 * phenomenon</a> and numerical problems (including NaN appearing).
55 * </p>
56 * <p>
57 * If the number of interpolation points or derivatives availability is not sufficient,
58 * the rate and acceleration of interpolated offset will be silently set to 0 (i.e.
59 * model will be constant or linear only).
60 * </p>
61 * @param interpolationPoints number of interpolation points
62 * @param extrapolationThreshold extrapolation threshold beyond which the propagation will fail
63 */
64 public ClockOffsetHermiteInterpolator(final int interpolationPoints, final double extrapolationThreshold) {
65 super(interpolationPoints, extrapolationThreshold);
66 }
67
68 /** {@inheritDoc} */
69 @Override
70 protected ClockOffset interpolate(final InterpolationData interpolationData) {
71 final HermiteInterpolator interpolator = new HermiteInterpolator();
72
73 // Fill interpolator with sample
74 final AbsoluteDate interpolationDate = interpolationData.getInterpolationDate();
75 final List<ClockOffset> neighborList = interpolationData.getNeighborList();
76 for (ClockOffset value : neighborList) {
77 final double deltaT = value.getDate().durationFrom(interpolationDate);
78 final double[] offset = new double[] { value.getOffset() };
79 if (Double.isNaN(value.getRate())) {
80 // no clock rate for this entry
81 interpolator.addSamplePoint(deltaT, offset);
82 } else {
83 // clock rate is available
84 final double[] rate = new double[] { value.getRate() };
85 if (Double.isNaN(value.getAcceleration())) {
86 // no clock acceleration for this entry
87 interpolator.addSamplePoint(deltaT, offset, rate);
88 } else {
89 // clock acceleration is available
90 final double[] acceleration = new double[] { value.getAcceleration() };
91 interpolator.addSamplePoint(deltaT, offset, rate, acceleration);
92 }
93 }
94 }
95
96 final double[][] y = interpolator.derivatives(0, 2);
97 return new ClockOffset(interpolationDate, y[0][0], y[1][0], y[2][0]);
98
99 }
100
101 }