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 018package org.apache.commons.math3.ode; 019 020import java.util.Collection; 021 022import org.apache.commons.math3.RealFieldElement; 023import org.apache.commons.math3.analysis.solvers.BracketedRealFieldUnivariateSolver; 024import org.apache.commons.math3.exception.MaxCountExceededException; 025import org.apache.commons.math3.exception.NoBracketingException; 026import org.apache.commons.math3.exception.NumberIsTooSmallException; 027import org.apache.commons.math3.ode.events.FieldEventHandler; 028import org.apache.commons.math3.ode.sampling.FieldStepHandler; 029 030/** This interface represents a first order integrator for 031 * differential equations. 032 033 * <p>The classes which are devoted to solve first order differential 034 * equations should implement this interface. The problems which can 035 * be handled should implement the {@link 036 * FirstOrderDifferentialEquations} interface.</p> 037 * 038 * @see FirstOrderFieldDifferentialEquations 039 * @param <T> the type of the field elements 040 * @since 3.6 041 */ 042 043public interface FirstOrderFieldIntegrator<T extends RealFieldElement<T>> { 044 045 /** Get the name of the method. 046 * @return name of the method 047 */ 048 String getName(); 049 050 /** Add a step handler to this integrator. 051 * <p>The handler will be called by the integrator for each accepted 052 * step.</p> 053 * @param handler handler for the accepted steps 054 * @see #getStepHandlers() 055 * @see #clearStepHandlers() 056 */ 057 void addStepHandler(FieldStepHandler<T> handler); 058 059 /** Get all the step handlers that have been added to the integrator. 060 * @return an unmodifiable collection of the added events handlers 061 * @see #addStepHandler(FieldStepHandler) 062 * @see #clearStepHandlers() 063 */ 064 Collection<FieldStepHandler<T>> getStepHandlers(); 065 066 /** Remove all the step handlers that have been added to the integrator. 067 * @see #addStepHandler(FieldStepHandler) 068 * @see #getStepHandlers() 069 */ 070 void clearStepHandlers(); 071 072 /** Add an event handler to the integrator. 073 * <p> 074 * The default solver is a 5<sup>th</sup> order {@link 075 * org.apache.commons.math3.analysis.solvers.FieldBracketingNthOrderBrentSolver}. 076 * </p> 077 * @param handler event handler 078 * @param maxCheckInterval maximal time interval between switching 079 * function checks (this interval prevents missing sign changes in 080 * case the integration steps becomes very large) 081 * @param convergence convergence threshold in the event time search 082 * @param maxIterationCount upper limit of the iteration count in 083 * the event time search events. 084 * @see #addEventHandler(FieldEventHandler, double, double, int, 085 * org.apache.commons.math3.analysis.solvers.BracketedRealFieldUnivariateSolver) 086 * @see #getEventHandlers() 087 * @see #clearEventHandlers() 088 */ 089 void addEventHandler(FieldEventHandler<T> handler, double maxCheckInterval, 090 double convergence, int maxIterationCount); 091 092 /** Add an event handler to the integrator. 093 * @param handler event handler 094 * @param maxCheckInterval maximal time interval between switching 095 * function checks (this interval prevents missing sign changes in 096 * case the integration steps becomes very large) 097 * @param convergence convergence threshold in the event time search 098 * @param maxIterationCount upper limit of the iteration count in 099 * the event time search events. 100 * @param solver solver to use to locate the event 101 * @see #addEventHandler(FieldEventHandler, double, double, int) 102 * @see #getEventHandlers() 103 * @see #clearEventHandlers() 104 */ 105 void addEventHandler(FieldEventHandler<T> handler, double maxCheckInterval, 106 double convergence, int maxIterationCount, 107 BracketedRealFieldUnivariateSolver<T> solver); 108 109 /** Get all the event handlers that have been added to the integrator. 110 * @return an unmodifiable collection of the added events handlers 111 * @see #addEventHandler(FieldEventHandler, double, double, int) 112 * @see #clearEventHandlers() 113 */ 114 Collection<FieldEventHandler<T> > getEventHandlers(); 115 116 /** Remove all the event handlers that have been added to the integrator. 117 * @see #addEventHandler(FieldEventHandler, double, double, int) 118 * @see #getEventHandlers() 119 */ 120 void clearEventHandlers(); 121 122 /** Get the current value of the step start time t<sub>i</sub>. 123 * <p>This method can be called during integration (typically by 124 * the object implementing the {@link FirstOrderDifferentialEquations 125 * differential equations} problem) if the value of the current step that 126 * is attempted is needed.</p> 127 * <p>The result is undefined if the method is called outside of 128 * calls to <code>integrate</code>.</p> 129 * @return current value of the state at step start time t<sub>i</sub> 130 */ 131 FieldODEStateAndDerivative<T> getCurrentStepStart(); 132 133 /** Get the current signed value of the integration stepsize. 134 * <p>This method can be called during integration (typically by 135 * the object implementing the {@link FirstOrderDifferentialEquations 136 * differential equations} problem) if the signed value of the current stepsize 137 * that is tried is needed.</p> 138 * <p>The result is undefined if the method is called outside of 139 * calls to <code>integrate</code>.</p> 140 * @return current signed value of the stepsize 141 */ 142 T getCurrentSignedStepsize(); 143 144 /** Set the maximal number of differential equations function evaluations. 145 * <p>The purpose of this method is to avoid infinite loops which can occur 146 * for example when stringent error constraints are set or when lots of 147 * discrete events are triggered, thus leading to many rejected steps.</p> 148 * @param maxEvaluations maximal number of function evaluations (negative 149 * values are silently converted to maximal integer value, thus representing 150 * almost unlimited evaluations) 151 */ 152 void setMaxEvaluations(int maxEvaluations); 153 154 /** Get the maximal number of functions evaluations. 155 * @return maximal number of functions evaluations 156 */ 157 int getMaxEvaluations(); 158 159 /** Get the number of evaluations of the differential equations function. 160 * <p> 161 * The number of evaluations corresponds to the last call to the 162 * <code>integrate</code> method. It is 0 if the method has not been called yet. 163 * </p> 164 * @return number of evaluations of the differential equations function 165 */ 166 int getEvaluations(); 167 168 /** Integrate the differential equations up to the given time. 169 * <p>This method solves an Initial Value Problem (IVP).</p> 170 * <p>Since this method stores some internal state variables made 171 * available in its public interface during integration ({@link 172 * #getCurrentSignedStepsize()}), it is <em>not</em> thread-safe.</p> 173 * @param equations differential equations to integrate 174 * @param initialState initial state (time, primary and secondary state vectors) 175 * @param finalTime target time for the integration 176 * (can be set to a value smaller than {@code t0} for backward integration) 177 * @return final state, its time will be the same as {@code finalTime} if 178 * integration reached its target, but may be different if some {@link 179 * org.apache.commons.math3.ode.events.FieldEventHandler} stops it at some point. 180 * @exception NumberIsTooSmallException if integration step is too small 181 * @exception MaxCountExceededException if the number of functions evaluations is exceeded 182 * @exception NoBracketingException if the location of an event cannot be bracketed 183 */ 184 FieldODEStateAndDerivative<T> integrate(FieldExpandableODE<T> equations, 185 FieldODEState<T> initialState, T finalTime) 186 throws NumberIsTooSmallException, MaxCountExceededException, NoBracketingException; 187 188}