package.html revision dee0849a9704d532af0b550146cbafbaa6ee1d19 
1<html>
2<!--
3   Licensed to the Apache Software Foundation (ASF) under one or more
4  contributor license agreements.  See the NOTICE file distributed with
5  this work for additional information regarding copyright ownership.
6  The ASF licenses this file to You under the Apache License, Version 2.0
7  (the "License"); you may not use this file except in compliance with
8  the License.  You may obtain a copy of the License at
9
10       http://www.apache.org/licenses/LICENSE-2.0
11
12   Unless required by applicable law or agreed to in writing, software
13   distributed under the License is distributed on an "AS IS" BASIS,
14   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
15   See the License for the specific language governing permissions and
16   limitations under the License.
17  -->
18    <!-- $Revision: 613620 $ -->
19<body>
20<p>
21This package provides classes to handle sampling steps during
22Ordinary Differential Equations integration.
23</p>
24
25<p>
26In addition to computing the evolution of the state vector at some grid points, all
27ODE integrators also build up interpolation models of this evolution <em>inside</em> the
28last computed step. If users are interested in these interpolators, they can register a
29{@link org.apache.commons.math.ode.sampling.StepHandler StepHandler} instance using the
30{@link org.apache.commons.math.ode.FirstOrderIntegrator#addStepHandler addStepHandler}
31method which is supported by all integrators. The integrator will call this instance
32at the end of each accepted step and provide it the interpolator. The user can do
33whatever he wants with this interpolator, which computes both the state and its
34time-derivative. A typical use of step handler is to provide some output to monitor
35the integration process.
36</p>
37
38<p>
39In a sense, this is a kind of Inversion Of Control: rather than having the master
40application driving the slave integrator by providing the target end value for
41the free variable, we get a master integrator scheduling the free variable
42evolution and calling the slave application callbacks that were registered at
43configuration time.
44</p>
45
46<p>
47Since some integrators may use variable step size, the generic {@link
48org.apache.commons.math.ode.sampling.StepHandler StepHandler} interface can be called
49either at regular or irregular rate. This interface allows to navigate to any location
50within the last computed step, thanks to the provided {@link
51org.apache.commons.math.ode.sampling.StepInterpolator StepInterpolator} object.
52If regular output is desired (for example in order to write an ephemeris file), then
53the simpler {@link org.apache.commons.math.ode.sampling.FixedStepHandler FixedStepHandler}
54interface can be used. Objects implementing this interface should be wrapped within a
55{@link org.apache.commons.math.ode.sampling.StepNormalizer StepNormalizer} instance
56in order to be registered to the integrator.
57</p>
58
59</body>
60</html>
61