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.CalculusFieldElement;
20 import org.hipparchus.analysis.interpolation.FieldHermiteInterpolator;
21 import org.hipparchus.analysis.interpolation.HermiteInterpolator;
22 import org.hipparchus.util.MathArrays;
23
24 import java.util.List;
25
26 /**bHermite interpolator of time stamped clock offsets.
27 * @param <T> type of the field elements
28 * @author Luc Maisonobe
29 * @see HermiteInterpolator
30 * @see TimeInterpolator
31 * @since 12.1
32 */
33 public class FieldClockOffsetHermiteInterpolator<T extends CalculusFieldElement<T>>
34 extends AbstractFieldTimeInterpolator<FieldClockOffset<T>, T> {
35
36 /**
37 * Constructor with default extrapolation threshold value ({@code DEFAULT_EXTRAPOLATION_THRESHOLD_SEC} s).
38 * <p>
39 * As this implementation of interpolation is polynomial, it should be used only with small number of interpolation
40 * points (about 10-20 points) in order to avoid <a href="http://en.wikipedia.org/wiki/Runge%27s_phenomenon">Runge's
41 * phenomenon</a> and numerical problems (including NaN appearing).
42 * </p>
43 * <p>
44 * If the number of interpolation points or derivatives availability is not sufficient,
45 * the rate and acceleration of interpolated offset will be silently set to 0 (i.e.
46 * model will be constant or linear only).
47 * </p>
48 * @param interpolationPoints number of interpolation points
49 */
50 public FieldClockOffsetHermiteInterpolator(final int interpolationPoints) {
51 this(interpolationPoints, DEFAULT_EXTRAPOLATION_THRESHOLD_SEC);
52 }
53
54 /**
55 * Constructor.
56 * <p>
57 * As this implementation of interpolation is polynomial, it should be used only with small number of interpolation
58 * points (about 10-20 points) in order to avoid <a href="http://en.wikipedia.org/wiki/Runge%27s_phenomenon">Runge's
59 * phenomenon</a> and numerical problems (including NaN appearing).
60 * </p>
61 * <p>
62 * If the number of interpolation points or derivatives availability is not sufficient,
63 * the rate and acceleration of interpolated offset will be silently set to 0 (i.e.
64 * model will be constant or linear only).
65 * </p>
66 * @param interpolationPoints number of interpolation points
67 * @param extrapolationThreshold extrapolation threshold beyond which the propagation will fail
68 */
69 public FieldClockOffsetHermiteInterpolator(final int interpolationPoints, final double extrapolationThreshold) {
70 super(interpolationPoints, extrapolationThreshold);
71 }
72
73 /** {@inheritDoc} */
74 @Override
75 protected FieldClockOffset<T> interpolate(final InterpolationData interpolationData) {
76 final FieldHermiteInterpolator<T> interpolator = new FieldHermiteInterpolator<>();
77
78 // Fill interpolator with sample
79 final FieldAbsoluteDate<T> interpolationDate = interpolationData.getInterpolationDate();
80 final List<FieldClockOffset<T>> neighborList = interpolationData.getNeighborList();
81 for (FieldClockOffset<T> value : neighborList) {
82 final T deltaT = value.getDate().durationFrom(interpolationDate);
83 final T[] offset = MathArrays.buildArray(interpolationDate.getField(), 1);
84 offset[0] = value.getOffset();
85 if (value.getRate() == null || value.getRate().isNaN()) {
86 // no clock rate for this entry
87 interpolator.addSamplePoint(deltaT, offset);
88 } else {
89 // clock rate is available
90 final T[] rate = MathArrays.buildArray(interpolationDate.getField(), 1);
91 rate[0] = value.getRate();
92 if (value.getAcceleration() == null || value.getAcceleration().isNaN()) {
93 // no clock acceleration for this entry
94 interpolator.addSamplePoint(deltaT, offset, rate);
95 } else {
96 // clock acceleration is available
97 final T[] acceleration = MathArrays.buildArray(interpolationDate.getField(), 1);
98 acceleration[0] = value.getAcceleration();
99 interpolator.addSamplePoint(deltaT, offset, rate, acceleration);
100 }
101 }
102 }
103
104 final T[][] y = interpolator.derivatives(interpolationDate.getField().getZero(), 2);
105 return new FieldClockOffset<>(interpolationDate, y[0][0], y[1][0], y[2][0]);
106
107 }
108
109 }