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
18package org.apache.commons.math.ode.sampling;
19
20import org.apache.commons.math.ode.DerivativeException;
21
22/**
23 * This interface represents a handler that should be called after
24 * each successful step.
25 *
26 * <p>The ODE integrators compute the evolution of the state vector at
27 * some grid points that depend on their own internal algorithm. Once
28 * they have found a new grid point (possibly after having computed
29 * several evaluation of the derivative at intermediate points), they
30 * provide it to objects implementing this interface. These objects
31 * typically either ignore the intermediate steps and wait for the
32 * last one, store the points in an ephemeris, or forward them to
33 * specialized processing or output methods.</p>
34 *
35 * @see org.apache.commons.math.ode.FirstOrderIntegrator
36 * @see org.apache.commons.math.ode.SecondOrderIntegrator
37 * @see StepInterpolator
38 * @version $Revision: 1073158 $ $Date: 2011-02-21 22:46:52 +0100 (lun. 21 févr. 2011) $
39 * @since 1.2
40 */
41
42public interface StepHandler {
43
44  /** Determines whether this handler needs dense output.
45   * <p>This method allows the integrator to avoid performing extra
46   * computation if the handler does not need dense output. If this
47   * method returns false, the integrator will call the {@link
48   * #handleStep} method with a {@link DummyStepInterpolator} rather
49   * than a custom interpolator.</p>
50   * @return true if the handler needs dense output
51   */
52  boolean requiresDenseOutput();
53
54  /** Reset the step handler.
55   * Initialize the internal data as required before the first step is
56   * handled.
57   */
58  void reset();
59
60  /**
61   * Handle the last accepted step
62   * @param interpolator interpolator for the last accepted step. For
63   * efficiency purposes, the various integrators reuse the same
64   * object on each call, so if the instance wants to keep it across
65   * all calls (for example to provide at the end of the integration a
66   * continuous model valid throughout the integration range, as the
67   * {@link org.apache.commons.math.ode.ContinuousOutputModel
68   * ContinuousOutputModel} class does), it should build a local copy
69   * using the clone method of the interpolator and store this copy.
70   * Keeping only a reference to the interpolator and reusing it will
71   * result in unpredictable behavior (potentially crashing the application).
72   * @param isLast true if the step is the last one
73   * @exception DerivativeException if user code called from step interpolator
74   * finalization triggers one
75   */
76  void handleStep(StepInterpolator interpolator, boolean isLast) throws DerivativeException;
77
78}
79