1 /* Contributed in the public domain.
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.propagation.events;
18
19 import java.util.function.ToDoubleFunction;
20
21 import org.orekit.propagation.SpacecraftState;
22 import org.orekit.propagation.events.handlers.ContinueOnEvent;
23 import org.orekit.propagation.events.handlers.EventHandler;
24 import org.orekit.propagation.events.intervals.AdaptableInterval;
25
26 /**
27 * A detector that implements the {@link #g(SpacecraftState)} function using a lambda that
28 * can be set using {@link #withFunction(ToDoubleFunction)}.
29 *
30 * <p>For example, to create a simple date detector use:
31 *
32 * <pre>
33 * FunctionalDetector d = new FunctionalDetector()
34 * .withGFunction((s) -> s.getDate().durationFrom(triggerDate))
35 * .withMaxCheck(1e10);
36 * </pre>
37 *
38 * @author Evan Ward
39 * @since 9.2
40 */
41 public class FunctionalDetector extends AbstractDetector<FunctionalDetector> {
42
43 /** The g function. */
44 private final ToDoubleFunction<SpacecraftState> function;
45
46 /**
47 * Create an event detector with the default values. These are {@link
48 * #DEFAULT_MAX_CHECK}, {@link #DEFAULT_THRESHOLD}, {@link #DEFAULT_MAX_ITER}, {@link
49 * ContinueOnEvent}, and a g function that is identically unity.
50 */
51 public FunctionalDetector() {
52 this(EventDetectionSettings.getDefaultEventDetectionSettings(), new ContinueOnEvent(), value -> 1.0);
53 }
54
55 /**
56 * Private constructor.
57 *
58 * @param detectionSettings event detection settings
59 * @param handler event handler to call at event occurrences
60 * @param function the switching function.
61 * @since 13.0
62 */
63 protected FunctionalDetector(final EventDetectionSettings detectionSettings,
64 final EventHandler handler,
65 final ToDoubleFunction<SpacecraftState> function) {
66 super(detectionSettings, handler);
67 this.function = function;
68 }
69
70
71 @Override
72 public double g(final SpacecraftState s) {
73 return function.applyAsDouble(s);
74 }
75
76 @Override
77 protected FunctionalDetector create(final EventDetectionSettings detectionSettings, final EventHandler newHandler) {
78
79 return new FunctionalDetector(detectionSettings, newHandler, function);
80 }
81
82 /**
83 * Create a new event detector with a new g function, keeping all other attributes the
84 * same. It is recommended to use {@link #withMaxCheck(AdaptableInterval)} and {@link
85 * #withThreshold(double)} to set appropriate values for this g function.
86 *
87 * @param newGFunction the new g function.
88 * @return a new detector with the new g function.
89 */
90 public FunctionalDetector withFunction(final ToDoubleFunction<SpacecraftState> newGFunction) {
91 return new FunctionalDetector(getDetectionSettings(), getHandler(), newGFunction);
92 }
93
94 /**
95 * Get the switching function.
96 *
97 * @return the function used in {@link #g(SpacecraftState)}.
98 */
99 public ToDoubleFunction<SpacecraftState> getFunction() {
100 return function;
101 }
102
103 }