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.math.ode.jacobians; 19 20 import 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 * <p>Note that is is possible to register a {@link 36 * org.apache.commons.math.ode.sampling.StepHandler classical step handler} 37 * in the low level integrator used to build a {@link FirstOrderIntegratorWithJacobians} 38 * rather than implementing this class. The step handlers registered at low level 39 * will see the big compound state whether the step handlers defined by this interface 40 * see the original state, and its jacobians in separate arrays.</p> 41 * 42 * <p>The compound state is guaranteed to contain the original state in the first 43 * elements, followed by the jacobian with respect to initial state (in row order), 44 * followed by the jacobian with respect to parameters (in row order). If for example 45 * the original state dimension is 6 and there are 3 parameters, the compound state will 46 * be a 60 elements array. The first 6 elements will be the original state, the next 36 47 * elements will be the jacobian with respect to initial state, and the remaining 18 elements 48 * will be the jacobian with respect to parameters.</p> 49 * 50 * <p>Dealing with low level step handlers is cumbersome if one really needs the jacobians 51 * in these methods, but it also prevents many data being copied back and forth between 52 * state and jacobians on one side and compound state on the other side. So for performance 53 * reasons, it is recommended to use this interface <em>only</em> if jacobians are really 54 * needed and to use lower level handlers if only state is needed.</p> 55 * 56 * @see FirstOrderIntegratorWithJacobians 57 * @see StepInterpolatorWithJacobians 58 * @version $Revision: 1073158 $ $Date: 2011-02-21 22:46:52 +0100 (lun. 21 fvr. 2011) $ 59 * @since 2.1 60 * @deprecated as of 2.2 the complete package is deprecated, it will be replaced 61 * in 3.0 by a completely rewritten implementation 62 */ 63 @Deprecated 64 public interface StepHandlerWithJacobians { 65 66 /** Determines whether this handler needs dense output. 67 * <p>This method allows the integrator to avoid performing extra 68 * computation if the handler does not need dense output.</p> 69 * @return true if the handler needs dense output 70 */ 71 boolean requiresDenseOutput(); 72 73 /** Reset the step handler. 74 * Initialize the internal data as required before the first step is 75 * handled. 76 */ 77 void reset(); 78 79 /** 80 * Handle the last accepted step 81 * @param interpolator interpolator for the last accepted step. For 82 * efficiency purposes, the various integrators reuse the same 83 * object on each call, so if the instance wants to keep it across 84 * all calls (for example to provide at the end of the integration a 85 * continuous model valid throughout the integration range, as the 86 * {@link org.apache.commons.math.ode.ContinuousOutputModel 87 * ContinuousOutputModel} class does), it should build a local copy 88 * using the clone method of the interpolator and store this copy. 89 * Keeping only a reference to the interpolator and reusing it will 90 * result in unpredictable behavior (potentially crashing the application). 91 * @param isLast true if the step is the last one 92 * @throws DerivativeException this exception is propagated to the 93 * caller if the underlying user function triggers one 94 */ 95 void handleStep(StepInterpolatorWithJacobians interpolator, boolean isLast) throws DerivativeException; 96 97 } 98
