/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.commons.math4.ode.events;
import org.apache.commons.math4.analysis.solvers.BrentSolver;
import org.apache.commons.math4.exception.DimensionMismatchException;
import org.apache.commons.math4.exception.MaxCountExceededException;
import org.apache.commons.math4.exception.NoBracketingException;
import org.apache.commons.math4.exception.NumberIsTooSmallException;
import org.apache.commons.math4.ode.ExpandableStatefulODE;
import org.apache.commons.math4.ode.FirstOrderDifferentialEquations;
import org.apache.commons.math4.ode.SecondaryEquations;
import org.apache.commons.math4.ode.events.EventHandler;
import org.apache.commons.math4.ode.events.EventState;
import org.apache.commons.math4.ode.nonstiff.DormandPrince853Integrator;
import org.apache.commons.math4.ode.nonstiff.LutherIntegrator;
import org.apache.commons.math4.ode.sampling.AbstractStepInterpolator;
import org.apache.commons.math4.ode.sampling.DummyStepInterpolator;
import org.junit.Assert;
import org.junit.Test;
public class EventStateTest {
// JIRA: MATH-322
@Test
public void closeEvents() throws MaxCountExceededException, NoBracketingException {
final double r1 = 90.0;
final double r2 = 135.0;
final double gap = r2 - r1;
final double tolerance = 0.1;
EventState es = new EventState(new CloseEventsGenerator(r1, r2), 1.5 * gap,
tolerance, 100,
new BrentSolver(tolerance));
es.setExpandable(new ExpandableStatefulODE(new FirstOrderDifferentialEquations() {
@Override
public int getDimension() {
return 0;
}
@Override
public void computeDerivatives(double t, double[] y, double[] yDot) {
}
}));
AbstractStepInterpolator interpolator =
new DummyStepInterpolator(new double[0], new double[0], true);
interpolator.storeTime(r1 - 2.5 * gap);
interpolator.shift();
interpolator.storeTime(r1 - 1.5 * gap);
es.reinitializeBegin(interpolator);
interpolator.shift();
interpolator.storeTime(r1 - 0.5 * gap);
Assert.assertFalse(es.evaluateStep(interpolator));
interpolator.shift();
interpolator.storeTime(0.5 * (r1 + r2));
Assert.assertTrue(es.evaluateStep(interpolator));
Assert.assertEquals(r1, es.getEventTime(), tolerance);
es.stepAccepted(es.getEventTime(), new double[0]);
interpolator.shift();
interpolator.storeTime(r2 + 0.4 * gap);
Assert.assertTrue(es.evaluateStep(interpolator));
Assert.assertEquals(r2, es.getEventTime(), tolerance);
}
// Jira: MATH-695
@Test
public void testIssue695()
throws DimensionMismatchException, NumberIsTooSmallException,
MaxCountExceededException, NoBracketingException {
FirstOrderDifferentialEquations equation = new FirstOrderDifferentialEquations() {
@Override
public int getDimension() {
return 1;
}
@Override
public void computeDerivatives(double t, double[] y, double[] yDot) {
yDot[0] = 1.0;
}
};
DormandPrince853Integrator integrator = new DormandPrince853Integrator(0.001, 1000, 1.0e-14, 1.0e-14);
integrator.addEventHandler(new ResettingEvent(10.99), 0.1, 1.0e-9, 1000);
integrator.addEventHandler(new ResettingEvent(11.01), 0.1, 1.0e-9, 1000);
integrator.setInitialStepSize(3.0);
double target = 30.0;
double[] y = new double[1];
double tEnd = integrator.integrate(equation, 0.0, y, target, y);
Assert.assertEquals(target, tEnd, 1.0e-10);
Assert.assertEquals(32.0, y[0], 1.0e-10);
}
private static class ResettingEvent implements EventHandler {
private static double lastTriggerTime = Double.NEGATIVE_INFINITY;
private final double tEvent;
public ResettingEvent(final double tEvent) {
this.tEvent = tEvent;
}
@Override
public void init(double t0, double[] y0, double t) {
}
@Override
public double g(double t, double[] y) {
// the bug corresponding to issue 695 causes the g function
// to be called at obsolete times t despite an event
// occurring later has already been triggered.
// When this occurs, the following assertion is violated
Assert.assertTrue("going backard in time! (" + t + " < " + lastTriggerTime + ")",
t >= lastTriggerTime);
return t - tEvent;
}
@Override
public Action eventOccurred(double t, double[] y, boolean increasing) {
// remember in a class variable when the event was triggered
lastTriggerTime = t;
return Action.RESET_STATE;
}
@Override
public void resetState(double t, double[] y) {
y[0] += 1.0;
}
}
// Jira: MATH-965
@Test
public void testIssue965()
throws DimensionMismatchException, NumberIsTooSmallException,
MaxCountExceededException, NoBracketingException {
ExpandableStatefulODE equation =
new ExpandableStatefulODE(new FirstOrderDifferentialEquations() {
@Override
public int getDimension() {
return 1;
}
@Override
public void computeDerivatives(double t, double[] y, double[] yDot) {
yDot[0] = 2.0;
}
});
equation.setTime(0.0);
equation.setPrimaryState(new double[1]);
equation.addSecondaryEquations(new SecondaryEquations() {
@Override
public int getDimension() {
return 1;
}
@Override
public void computeDerivatives(double t, double[] primary,
double[] primaryDot, double[] secondary,
double[] secondaryDot) {
secondaryDot[0] = -3.0;
}
});
int index = equation.getSecondaryMappers()[0].getFirstIndex();
DormandPrince853Integrator integrator = new DormandPrince853Integrator(0.001, 1000, 1.0e-14, 1.0e-14);
integrator.addEventHandler(new SecondaryStateEvent(index, -3.0), 0.1, 1.0e-9, 1000);
integrator.setInitialStepSize(3.0);
integrator.integrate(equation, 30.0);
Assert.assertEquals( 1.0, equation.getTime(), 1.0e-10);
Assert.assertEquals( 2.0, equation.getPrimaryState()[0], 1.0e-10);
Assert.assertEquals(-3.0, equation.getSecondaryState(0)[0], 1.0e-10);
}
private static class SecondaryStateEvent implements EventHandler {
private int index;
private final double target;
public SecondaryStateEvent(final int index, final double target) {
this.index = index;
this.target = target;
}
@Override
public void init(double t0, double[] y0, double t) {
}
@Override
public double g(double t, double[] y) {
return y[index] - target;
}
@Override
public Action eventOccurred(double t, double[] y, boolean increasing) {
return Action.STOP;
}
@Override
public void resetState(double t, double[] y) {
}
}
@Test
public void testEventsCloserThanThreshold()
throws DimensionMismatchException, NumberIsTooSmallException,
MaxCountExceededException, NoBracketingException {
FirstOrderDifferentialEquations equation = new FirstOrderDifferentialEquations() {
@Override
public int getDimension() {
return 1;
}
@Override
public void computeDerivatives(double t, double[] y, double[] yDot) {
yDot[0] = 1.0;
}
};
LutherIntegrator integrator = new LutherIntegrator(20.0);
CloseEventsGenerator eventsGenerator =
new CloseEventsGenerator(9.0 - 1.0 / 128, 9.0 + 1.0 / 128);
integrator.addEventHandler(eventsGenerator, 1.0, 0.02, 1000);
double[] y = new double[1];
double tEnd = integrator.integrate(equation, 0.0, y, 100.0, y);
Assert.assertEquals( 2, eventsGenerator.getCount());
Assert.assertEquals( 9.0 + 1.0 / 128, tEnd, 1.0 / 32.0);
}
private class CloseEventsGenerator implements EventHandler {
final double r1;
final double r2;
int count;
public CloseEventsGenerator(final double r1, final double r2) {
this.r1 = r1;
this.r2 = r2;
this.count = 0;
}
@Override
public void init(double t0, double[] y0, double t) {
}
@Override
public void resetState(double t, double[] y) {
}
@Override
public double g(double t, double[] y) {
return (t - r1) * (r2 - t);
}
@Override
public Action eventOccurred(double t, double[] y, boolean increasing) {
return ++count < 2 ? Action.CONTINUE : Action.STOP;
}
public int getCount() {
return count;
}
}
}