1 /*
2 * Licensed to the Apache Software Foundation (ASF) under one or more
3 * contributor license agreements. See the NOTICE file distributed with
4 * this work for additional information regarding copyright ownership.
5 * The ASF 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
18 package org.apache.commons.math4.legacy.ode.sampling;
19
20 import org.apache.commons.math4.legacy.core.RealFieldElement;
21 import org.apache.commons.math4.legacy.ode.FieldODEStateAndDerivative;
22
23 /**
24 * This interface represents a handler that should be called after
25 * each successful fixed step.
26
27 * <p>This interface should be implemented by anyone who is interested
28 * in getting the solution of an ordinary differential equation at
29 * fixed time steps. Objects implementing this interface should be
30 * wrapped within an instance of {@link FieldStepNormalizer} that itself
31 * is used as the general {@link FieldStepHandler} by the integrator. The
32 * {@link FieldStepNormalizer} object is called according to the integrator
33 * internal algorithms and it calls objects implementing this
34 * interface as necessary at fixed time steps.</p>
35 *
36 * @see FieldStepHandler
37 * @see FieldStepNormalizer
38 * @see FieldStepInterpolator
39 * @param <T> the type of the field elements
40 * @since 3.6
41 */
42
43 public interface FieldFixedStepHandler<T extends RealFieldElement<T>> {
44
45 /** Initialize step handler at the start of an ODE integration.
46 * <p>
47 * This method is called once at the start of the integration. It
48 * may be used by the step handler to initialize some internal data
49 * if needed.
50 * </p>
51 * @param initialState initial time, state vector and derivative
52 * @param finalTime target time for the integration
53 */
54 void init(FieldODEStateAndDerivative<T> initialState, T finalTime);
55
56 /**
57 * Handle the last accepted step.
58 * @param state current value of the independent <i>time</i> variable,
59 * state vector and derivative
60 * For efficiency purposes, the {@link FieldStepNormalizer} class reuses
61 * the same array on each call, so if
62 * the instance wants to keep it across all calls (for example to
63 * provide at the end of the integration a complete array of all
64 * steps), it should build a local copy store this copy.
65 * @param isLast true if the step is the last one
66 */
67 void handleStep(FieldODEStateAndDerivative<T> state, boolean isLast);
68 }