001 /*
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements. See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License. You may obtain a copy of the License at
008 *
009 * http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017
018 package org.apache.commons.math.ode.sampling;
019
020 import org.apache.commons.math.ode.DerivativeException;
021
022 /**
023 * This interface represents a handler that should be called after
024 * each successful fixed step.
025
026 * <p>This interface should be implemented by anyone who is interested
027 * in getting the solution of an ordinary differential equation at
028 * fixed time steps. Objects implementing this interface should be
029 * wrapped within an instance of {@link StepNormalizer} that itself
030 * is used as the general {@link StepHandler} by the integrator. The
031 * {@link StepNormalizer} object is called according to the integrator
032 * internal algorithms and it calls objects implementing this
033 * interface as necessary at fixed time steps.</p>
034 *
035 * @see StepHandler
036 * @see StepNormalizer
037 * @version $Revision: 811786 $ $Date: 2009-09-06 05:36:08 -0400 (Sun, 06 Sep 2009) $
038 * @since 1.2
039 */
040
041 public interface FixedStepHandler {
042
043 /**
044 * Handle the last accepted step
045 * @param t time of the current step
046 * @param y state vector at t. For efficiency purposes, the {@link
047 * StepNormalizer} class reuses the same array on each call, so if
048 * the instance wants to keep it across all calls (for example to
049 * provide at the end of the integration a complete array of all
050 * steps), it should build a local copy store this copy.
051 * @param yDot derivatives of the state vector state vector at t.
052 * For efficiency purposes, the {@link StepNormalizer} class reuses
053 * the same array on each call, so if
054 * the instance wants to keep it across all calls (for example to
055 * provide at the end of the integration a complete array of all
056 * steps), it should build a local copy store this copy.
057 * @param isLast true if the step is the last one
058 * @throws DerivativeException if some error condition is encountered
059 */
060 void handleStep(double t, double[] y, double[] yDot, boolean isLast) throws DerivativeException;
061
062 }