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.CalculusFieldElement;
20  import org.orekit.time.FieldAbsoluteDate;
21  
22  /** Quadratic clock model.
23   *
24   * @param <T> type of the field elements
25   * @author Luc Maisonobe
26   * @since 12.1
27   *
28   */
29  public class QuadraticFieldClockModel<T extends CalculusFieldElement<T>> {
30  
31      /** Clock model reference date. */
32      private final FieldAbsoluteDate<T> referenceDate;
33  
34      /** Constant term. */
35      private final T a0;
36  
37      /** Linear term. */
38      private final T a1;
39  
40      /** Quadratic term. */
41      private final T a2;
42  
43      /** Simple constructor.
44       * @param referenceDate reference date
45       * @param a0 constant term
46       * @param a1 linear term
47       * @param a2 quadratic term
48       */
49      public QuadraticFieldClockModel(final FieldAbsoluteDate<T> referenceDate,
50                                      final T a0, final T a1, final T a2) {
51          this.referenceDate = referenceDate;
52          this.a0            = a0;
53          this.a1            = a1;
54          this.a2            = a2;
55      }
56  
57      /** Get the clock offset at date.
58       * @param date date at which offset is requested
59       * @return clock offset at specified date
60       */
61      public FieldClockOffset<T> getOffset(final FieldAbsoluteDate<T> date) {
62          final T dt = date.durationFrom(referenceDate);
63          return new FieldClockOffset<>(date,
64                                        a2.multiply(dt).add(a1).multiply(dt).add(a0),
65                                        a2.multiply(dt).multiply(2).add(a1),
66                                        a2.multiply(2));
67      }
68  
69  }