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.sampling; 019 020import org.apache.commons.math3.RealFieldElement; 021import org.apache.commons.math3.exception.MaxCountExceededException; 022import org.apache.commons.math3.ode.FieldODEStateAndDerivative; 023import org.apache.commons.math3.util.FastMath; 024import org.apache.commons.math3.util.Precision; 025 026/** 027 * This class wraps an object implementing {@link FieldFixedStepHandler} 028 * into a {@link FieldStepHandler}. 029 030 * <p>This wrapper allows to use fixed step handlers with general 031 * integrators which cannot guaranty their integration steps will 032 * remain constant and therefore only accept general step 033 * handlers.</p> 034 * 035 * <p>The stepsize used is selected at construction time. The {@link 036 * FieldFixedStepHandler#handleStep handleStep} method of the underlying 037 * {@link FieldFixedStepHandler} object is called at normalized times. The 038 * normalized times can be influenced by the {@link StepNormalizerMode} and 039 * {@link StepNormalizerBounds}.</p> 040 * 041 * <p>There is no constraint on the integrator, it can use any time step 042 * it needs (time steps longer or shorter than the fixed time step and 043 * non-integer ratios are all allowed).</p> 044 * 045 * <p> 046 * <table border="1" align="center"> 047 * <tr BGCOLOR="#CCCCFF"><td colspan=6><font size="+2">Examples (step size = 0.5)</font></td></tr> 048 * <tr BGCOLOR="#EEEEFF"><font size="+1"><td>Start time</td><td>End time</td> 049 * <td>Direction</td><td>{@link StepNormalizerMode Mode}</td> 050 * <td>{@link StepNormalizerBounds Bounds}</td><td>Output</td></font></tr> 051 * <tr><td>0.3</td><td>3.1</td><td>forward</td><td>{@link StepNormalizerMode#INCREMENT INCREMENT}</td><td>{@link StepNormalizerBounds#NEITHER NEITHER}</td><td>0.8, 1.3, 1.8, 2.3, 2.8</td></tr> 052 * <tr><td>0.3</td><td>3.1</td><td>forward</td><td>{@link StepNormalizerMode#INCREMENT INCREMENT}</td><td>{@link StepNormalizerBounds#FIRST FIRST}</td><td>0.3, 0.8, 1.3, 1.8, 2.3, 2.8</td></tr> 053 * <tr><td>0.3</td><td>3.1</td><td>forward</td><td>{@link StepNormalizerMode#INCREMENT INCREMENT}</td><td>{@link StepNormalizerBounds#LAST LAST}</td><td>0.8, 1.3, 1.8, 2.3, 2.8, 3.1</td></tr> 054 * <tr><td>0.3</td><td>3.1</td><td>forward</td><td>{@link StepNormalizerMode#INCREMENT INCREMENT}</td><td>{@link StepNormalizerBounds#BOTH BOTH}</td><td>0.3, 0.8, 1.3, 1.8, 2.3, 2.8, 3.1</td></tr> 055 * <tr><td>0.3</td><td>3.1</td><td>forward</td><td>{@link StepNormalizerMode#MULTIPLES MULTIPLES}</td><td>{@link StepNormalizerBounds#NEITHER NEITHER}</td><td>0.5, 1.0, 1.5, 2.0, 2.5, 3.0</td></tr> 056 * <tr><td>0.3</td><td>3.1</td><td>forward</td><td>{@link StepNormalizerMode#MULTIPLES MULTIPLES}</td><td>{@link StepNormalizerBounds#FIRST FIRST}</td><td>0.3, 0.5, 1.0, 1.5, 2.0, 2.5, 3.0</td></tr> 057 * <tr><td>0.3</td><td>3.1</td><td>forward</td><td>{@link StepNormalizerMode#MULTIPLES MULTIPLES}</td><td>{@link StepNormalizerBounds#LAST LAST}</td><td>0.5, 1.0, 1.5, 2.0, 2.5, 3.0, 3.1</td></tr> 058 * <tr><td>0.3</td><td>3.1</td><td>forward</td><td>{@link StepNormalizerMode#MULTIPLES MULTIPLES}</td><td>{@link StepNormalizerBounds#BOTH BOTH}</td><td>0.3, 0.5, 1.0, 1.5, 2.0, 2.5, 3.0, 3.1</td></tr> 059 * <tr><td>0.0</td><td>3.0</td><td>forward</td><td>{@link StepNormalizerMode#INCREMENT INCREMENT}</td><td>{@link StepNormalizerBounds#NEITHER NEITHER}</td><td>0.5, 1.0, 1.5, 2.0, 2.5, 3.0</td></tr> 060 * <tr><td>0.0</td><td>3.0</td><td>forward</td><td>{@link StepNormalizerMode#INCREMENT INCREMENT}</td><td>{@link StepNormalizerBounds#FIRST FIRST}</td><td>0.0, 0.5, 1.0, 1.5, 2.0, 2.5, 3.0</td></tr> 061 * <tr><td>0.0</td><td>3.0</td><td>forward</td><td>{@link StepNormalizerMode#INCREMENT INCREMENT}</td><td>{@link StepNormalizerBounds#LAST LAST}</td><td>0.5, 1.0, 1.5, 2.0, 2.5, 3.0</td></tr> 062 * <tr><td>0.0</td><td>3.0</td><td>forward</td><td>{@link StepNormalizerMode#INCREMENT INCREMENT}</td><td>{@link StepNormalizerBounds#BOTH BOTH}</td><td>0.0, 0.5, 1.0, 1.5, 2.0, 2.5, 3.0</td></tr> 063 * <tr><td>0.0</td><td>3.0</td><td>forward</td><td>{@link StepNormalizerMode#MULTIPLES MULTIPLES}</td><td>{@link StepNormalizerBounds#NEITHER NEITHER}</td><td>0.5, 1.0, 1.5, 2.0, 2.5, 3.0</td></tr> 064 * <tr><td>0.0</td><td>3.0</td><td>forward</td><td>{@link StepNormalizerMode#MULTIPLES MULTIPLES}</td><td>{@link StepNormalizerBounds#FIRST FIRST}</td><td>0.0, 0.5, 1.0, 1.5, 2.0, 2.5, 3.0</td></tr> 065 * <tr><td>0.0</td><td>3.0</td><td>forward</td><td>{@link StepNormalizerMode#MULTIPLES MULTIPLES}</td><td>{@link StepNormalizerBounds#LAST LAST}</td><td>0.5, 1.0, 1.5, 2.0, 2.5, 3.0</td></tr> 066 * <tr><td>0.0</td><td>3.0</td><td>forward</td><td>{@link StepNormalizerMode#MULTIPLES MULTIPLES}</td><td>{@link StepNormalizerBounds#BOTH BOTH}</td><td>0.0, 0.5, 1.0, 1.5, 2.0, 2.5, 3.0</td></tr> 067 * <tr><td>3.1</td><td>0.3</td><td>backward</td><td>{@link StepNormalizerMode#INCREMENT INCREMENT}</td><td>{@link StepNormalizerBounds#NEITHER NEITHER}</td><td>2.6, 2.1, 1.6, 1.1, 0.6</td></tr> 068 * <tr><td>3.1</td><td>0.3</td><td>backward</td><td>{@link StepNormalizerMode#INCREMENT INCREMENT}</td><td>{@link StepNormalizerBounds#FIRST FIRST}</td><td>3.1, 2.6, 2.1, 1.6, 1.1, 0.6</td></tr> 069 * <tr><td>3.1</td><td>0.3</td><td>backward</td><td>{@link StepNormalizerMode#INCREMENT INCREMENT}</td><td>{@link StepNormalizerBounds#LAST LAST}</td><td>2.6, 2.1, 1.6, 1.1, 0.6, 0.3</td></tr> 070 * <tr><td>3.1</td><td>0.3</td><td>backward</td><td>{@link StepNormalizerMode#INCREMENT INCREMENT}</td><td>{@link StepNormalizerBounds#BOTH BOTH}</td><td>3.1, 2.6, 2.1, 1.6, 1.1, 0.6, 0.3</td></tr> 071 * <tr><td>3.1</td><td>0.3</td><td>backward</td><td>{@link StepNormalizerMode#MULTIPLES MULTIPLES}</td><td>{@link StepNormalizerBounds#NEITHER NEITHER}</td><td>3.0, 2.5, 2.0, 1.5, 1.0, 0.5</td></tr> 072 * <tr><td>3.1</td><td>0.3</td><td>backward</td><td>{@link StepNormalizerMode#MULTIPLES MULTIPLES}</td><td>{@link StepNormalizerBounds#FIRST FIRST}</td><td>3.1, 3.0, 2.5, 2.0, 1.5, 1.0, 0.5</td></tr> 073 * <tr><td>3.1</td><td>0.3</td><td>backward</td><td>{@link StepNormalizerMode#MULTIPLES MULTIPLES}</td><td>{@link StepNormalizerBounds#LAST LAST}</td><td>3.0, 2.5, 2.0, 1.5, 1.0, 0.5, 0.3</td></tr> 074 * <tr><td>3.1</td><td>0.3</td><td>backward</td><td>{@link StepNormalizerMode#MULTIPLES MULTIPLES}</td><td>{@link StepNormalizerBounds#BOTH BOTH}</td><td>3.1, 3.0, 2.5, 2.0, 1.5, 1.0, 0.5, 0.3</td></tr> 075 * <tr><td>3.0</td><td>0.0</td><td>backward</td><td>{@link StepNormalizerMode#INCREMENT INCREMENT}</td><td>{@link StepNormalizerBounds#NEITHER NEITHER}</td><td>2.5, 2.0, 1.5, 1.0, 0.5, 0.0</td></tr> 076 * <tr><td>3.0</td><td>0.0</td><td>backward</td><td>{@link StepNormalizerMode#INCREMENT INCREMENT}</td><td>{@link StepNormalizerBounds#FIRST FIRST}</td><td>3.0, 2.5, 2.0, 1.5, 1.0, 0.5, 0.0</td></tr> 077 * <tr><td>3.0</td><td>0.0</td><td>backward</td><td>{@link StepNormalizerMode#INCREMENT INCREMENT}</td><td>{@link StepNormalizerBounds#LAST LAST}</td><td>2.5, 2.0, 1.5, 1.0, 0.5, 0.0</td></tr> 078 * <tr><td>3.0</td><td>0.0</td><td>backward</td><td>{@link StepNormalizerMode#INCREMENT INCREMENT}</td><td>{@link StepNormalizerBounds#BOTH BOTH}</td><td>3.0, 2.5, 2.0, 1.5, 1.0, 0.5, 0.0</td></tr> 079 * <tr><td>3.0</td><td>0.0</td><td>backward</td><td>{@link StepNormalizerMode#MULTIPLES MULTIPLES}</td><td>{@link StepNormalizerBounds#NEITHER NEITHER}</td><td>2.5, 2.0, 1.5, 1.0, 0.5, 0.0</td></tr> 080 * <tr><td>3.0</td><td>0.0</td><td>backward</td><td>{@link StepNormalizerMode#MULTIPLES MULTIPLES}</td><td>{@link StepNormalizerBounds#FIRST FIRST}</td><td>3.0, 2.5, 2.0, 1.5, 1.0, 0.5, 0.0</td></tr> 081 * <tr><td>3.0</td><td>0.0</td><td>backward</td><td>{@link StepNormalizerMode#MULTIPLES MULTIPLES}</td><td>{@link StepNormalizerBounds#LAST LAST}</td><td>2.5, 2.0, 1.5, 1.0, 0.5, 0.0</td></tr> 082 * <tr><td>3.0</td><td>0.0</td><td>backward</td><td>{@link StepNormalizerMode#MULTIPLES MULTIPLES}</td><td>{@link StepNormalizerBounds#BOTH BOTH}</td><td>3.0, 2.5, 2.0, 1.5, 1.0, 0.5, 0.0</td></tr> 083 * </table> 084 * </p> 085 * 086 * @param <T> the type of the field elements 087 * @see FieldStepHandler 088 * @see FieldFixedStepHandler 089 * @see StepNormalizerMode 090 * @see StepNormalizerBounds 091 * @since 3.6 092 */ 093 094public class FieldStepNormalizer<T extends RealFieldElement<T>> implements FieldStepHandler<T> { 095 096 /** Fixed time step. */ 097 private double h; 098 099 /** Underlying step handler. */ 100 private final FieldFixedStepHandler<T> handler; 101 102 /** First step state. */ 103 private FieldODEStateAndDerivative<T> first; 104 105 /** Last step step. */ 106 private FieldODEStateAndDerivative<T> last; 107 108 /** Integration direction indicator. */ 109 private boolean forward; 110 111 /** The step normalizer bounds settings to use. */ 112 private final StepNormalizerBounds bounds; 113 114 /** The step normalizer mode to use. */ 115 private final StepNormalizerMode mode; 116 117 /** Simple constructor. Uses {@link StepNormalizerMode#INCREMENT INCREMENT} 118 * mode, and {@link StepNormalizerBounds#FIRST FIRST} bounds setting, for 119 * backwards compatibility. 120 * @param h fixed time step (sign is not used) 121 * @param handler fixed time step handler to wrap 122 */ 123 public FieldStepNormalizer(final double h, final FieldFixedStepHandler<T> handler) { 124 this(h, handler, StepNormalizerMode.INCREMENT, 125 StepNormalizerBounds.FIRST); 126 } 127 128 /** Simple constructor. Uses {@link StepNormalizerBounds#FIRST FIRST} 129 * bounds setting. 130 * @param h fixed time step (sign is not used) 131 * @param handler fixed time step handler to wrap 132 * @param mode step normalizer mode to use 133 * @since 3.0 134 */ 135 public FieldStepNormalizer(final double h, final FieldFixedStepHandler<T> handler, 136 final StepNormalizerMode mode) { 137 this(h, handler, mode, StepNormalizerBounds.FIRST); 138 } 139 140 /** Simple constructor. Uses {@link StepNormalizerMode#INCREMENT INCREMENT} 141 * mode. 142 * @param h fixed time step (sign is not used) 143 * @param handler fixed time step handler to wrap 144 * @param bounds step normalizer bounds setting to use 145 * @since 3.0 146 */ 147 public FieldStepNormalizer(final double h, final FieldFixedStepHandler<T> handler, 148 final StepNormalizerBounds bounds) { 149 this(h, handler, StepNormalizerMode.INCREMENT, bounds); 150 } 151 152 /** Simple constructor. 153 * @param h fixed time step (sign is not used) 154 * @param handler fixed time step handler to wrap 155 * @param mode step normalizer mode to use 156 * @param bounds step normalizer bounds setting to use 157 * @since 3.0 158 */ 159 public FieldStepNormalizer(final double h, final FieldFixedStepHandler<T> handler, 160 final StepNormalizerMode mode, final StepNormalizerBounds bounds) { 161 this.h = FastMath.abs(h); 162 this.handler = handler; 163 this.mode = mode; 164 this.bounds = bounds; 165 first = null; 166 last = null; 167 forward = true; 168 } 169 170 /** {@inheritDoc} */ 171 public void init(final FieldODEStateAndDerivative<T> initialState, final T finalTime) { 172 173 first = null; 174 last = null; 175 forward = true; 176 177 // initialize the underlying handler 178 handler.init(initialState, finalTime); 179 180 } 181 182 /** 183 * Handle the last accepted step 184 * @param interpolator interpolator for the last accepted step. For 185 * efficiency purposes, the various integrators reuse the same 186 * object on each call, so if the instance wants to keep it across 187 * all calls (for example to provide at the end of the integration a 188 * continuous model valid throughout the integration range), it 189 * should build a local copy using the clone method and store this 190 * copy. 191 * @param isLast true if the step is the last one 192 * @exception MaxCountExceededException if the interpolator throws one because 193 * the number of functions evaluations is exceeded 194 */ 195 public void handleStep(final FieldStepInterpolator<T> interpolator, final boolean isLast) 196 throws MaxCountExceededException { 197 // The first time, update the last state with the start information. 198 if (last == null) { 199 200 first = interpolator.getPreviousState(); 201 last = first; 202 203 // Take the integration direction into account. 204 forward = interpolator.isForward(); 205 if (!forward) { 206 h = -h; 207 } 208 } 209 210 // Calculate next normalized step time. 211 T nextTime = (mode == StepNormalizerMode.INCREMENT) ? 212 last.getTime().add(h) : 213 last.getTime().getField().getZero().add((FastMath.floor(last.getTime().getReal() / h) + 1) * h); 214 if (mode == StepNormalizerMode.MULTIPLES && 215 Precision.equals(nextTime.getReal(), last.getTime().getReal(), 1)) { 216 nextTime = nextTime.add(h); 217 } 218 219 // Process normalized steps as long as they are in the current step. 220 boolean nextInStep = isNextInStep(nextTime, interpolator); 221 while (nextInStep) { 222 // Output the stored previous step. 223 doNormalizedStep(false); 224 225 // Store the next step as last step. 226 last = interpolator.getInterpolatedState(nextTime); 227 228 // Move on to the next step. 229 nextTime = nextTime.add(h); 230 nextInStep = isNextInStep(nextTime, interpolator); 231 } 232 233 if (isLast) { 234 // There will be no more steps. The stored one should be given to 235 // the handler. We may have to output one more step. Only the last 236 // one of those should be flagged as being the last. 237 final boolean addLast = bounds.lastIncluded() && 238 last.getTime().getReal() != interpolator.getCurrentState().getTime().getReal(); 239 doNormalizedStep(!addLast); 240 if (addLast) { 241 last = interpolator.getCurrentState(); 242 doNormalizedStep(true); 243 } 244 } 245 } 246 247 /** 248 * Returns a value indicating whether the next normalized time is in the 249 * current step. 250 * @param nextTime the next normalized time 251 * @param interpolator interpolator for the last accepted step, to use to 252 * get the end time of the current step 253 * @return value indicating whether the next normalized time is in the 254 * current step 255 */ 256 private boolean isNextInStep(final T nextTime, final FieldStepInterpolator<T> interpolator) { 257 return forward ? 258 nextTime.getReal() <= interpolator.getCurrentState().getTime().getReal() : 259 nextTime.getReal() >= interpolator.getCurrentState().getTime().getReal(); 260 } 261 262 /** 263 * Invokes the underlying step handler for the current normalized step. 264 * @param isLast true if the step is the last one 265 */ 266 private void doNormalizedStep(final boolean isLast) { 267 if (!bounds.firstIncluded() && first.getTime().getReal() == last.getTime().getReal()) { 268 return; 269 } 270 handler.handleStep(last, isLast); 271 } 272 273}