FunctionalDetector.java
/* Contributed in the public domain.
* Licensed to CS GROUP (CS) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* CS licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.orekit.propagation.events;
import java.util.function.ToDoubleFunction;
import org.orekit.propagation.SpacecraftState;
import org.orekit.propagation.events.handlers.ContinueOnEvent;
import org.orekit.propagation.events.handlers.EventHandler;
/**
* A detector that implements the {@link #g(SpacecraftState)} function using a lambda that
* can be set using {@link #withFunction(ToDoubleFunction)}.
*
* <p>For example, to create a simple date detector use:
*
* <pre>
* FunctionalDetector d = new FunctionalDetector()
* .withGFunction((s) -> s.getDate().durationFrom(triggerDate))
* .withMaxCheck(1e10);
* </pre>
*
* @author Evan Ward
* @since 9.2
*/
public class FunctionalDetector extends AbstractDetector<FunctionalDetector> {
/** The g function. */
private final ToDoubleFunction<SpacecraftState> function;
/**
* Create an event detector with the default values. These are {@link
* #DEFAULT_MAXCHECK}, {@link #DEFAULT_THRESHOLD}, {@link #DEFAULT_MAX_ITER}, {@link
* ContinueOnEvent}, and a g function that is identically unity.
*/
public FunctionalDetector() {
this(DEFAULT_MAXCHECK, DEFAULT_THRESHOLD, DEFAULT_MAX_ITER,
new ContinueOnEvent<>(),
(ToDoubleFunction<SpacecraftState>) value -> 1.0);
}
/**
* Private constructor.
*
* @param maxCheck maximum checking interval (s)
* @param threshold convergence threshold (s)
* @param maxIter maximum number of iterations in the event time search
* @param handler event handler to call at event occurrences
* @param function the switching function.
*/
private FunctionalDetector(final double maxCheck,
final double threshold,
final int maxIter,
final EventHandler<? super FunctionalDetector> handler,
final ToDoubleFunction<SpacecraftState> function) {
super(maxCheck, threshold, maxIter, handler);
this.function = function;
}
@Override
public double g(final SpacecraftState s) {
return function.applyAsDouble(s);
}
@Override
protected FunctionalDetector create(
final double newMaxCheck,
final double newThreshold,
final int newMaxIter,
final EventHandler<? super FunctionalDetector> newHandler) {
return new FunctionalDetector(newMaxCheck, newThreshold, newMaxIter, newHandler,
function);
}
/**
* Create a new event detector with a new g function, keeping all other attributes the
* same. It is recommended to use {@link #withMaxCheck(double)} and {@link
* #withThreshold(double)} to set appropriate values for this g function.
*
* @param newGFunction the new g function.
* @return a new detector with the new g function.
*/
public FunctionalDetector withFunction(
final ToDoubleFunction<SpacecraftState> newGFunction) {
return new FunctionalDetector(getMaxCheckInterval(), getThreshold(),
getMaxIterationCount(), getHandler(), newGFunction);
}
/**
* Get the switching function.
*
* @return the function used in {@link #g(SpacecraftState)}.
*/
public ToDoubleFunction<SpacecraftState> getFunction() {
return function;
}
}