/*
* 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.math.analysis.integration;
import org.apache.commons.math.MathException;
import org.apache.commons.math.analysis.QuinticFunction;
import org.apache.commons.math.analysis.SinFunction;
import org.apache.commons.math.analysis.UnivariateRealFunction;
import junit.framework.TestCase;
/**
* Testcase for trapezoid integrator.
* <p>
* Test runs show that for a default relative accuracy of 1E-6, it
* generally takes 10 to 15 iterations for the integral to converge.
*
* @version $Revision: 811685 $ $Date: 2009-09-05 13:36:48 -0400 (Sat, 05 Sep 2009) $
*/
public final class TrapezoidIntegratorTest extends TestCase {
/**
* Test of integrator for the sine function.
*/
public void testSinFunction() throws MathException {
UnivariateRealFunction f = new SinFunction();
UnivariateRealIntegrator integrator = new TrapezoidIntegrator();
double min, max, expected, result, tolerance;
min = 0; max = Math.PI; expected = 2;
tolerance = Math.abs(expected * integrator.getRelativeAccuracy());
result = integrator.integrate(f, min, max);
assertEquals(expected, result, tolerance);
min = -Math.PI/3; max = 0; expected = -0.5;
tolerance = Math.abs(expected * integrator.getRelativeAccuracy());
result = integrator.integrate(f, min, max);
assertEquals(expected, result, tolerance);
}
/**
* Test of integrator for the quintic function.
*/
public void testQuinticFunction() throws MathException {
UnivariateRealFunction f = new QuinticFunction();
UnivariateRealIntegrator integrator = new TrapezoidIntegrator();
double min, max, expected, result, tolerance;
min = 0; max = 1; expected = -1.0/48;
tolerance = Math.abs(expected * integrator.getRelativeAccuracy());
result = integrator.integrate(f, min, max);
assertEquals(expected, result, tolerance);
min = 0; max = 0.5; expected = 11.0/768;
tolerance = Math.abs(expected * integrator.getRelativeAccuracy());
result = integrator.integrate(f, min, max);
assertEquals(expected, result, tolerance);
min = -1; max = 4; expected = 2048/3.0 - 78 + 1.0/48;
tolerance = Math.abs(expected * integrator.getRelativeAccuracy());
result = integrator.integrate(f, min, max);
assertEquals(expected, result, tolerance);
}
/**
* Test of parameters for the integrator.
*/
public void testParameters() throws Exception {
UnivariateRealFunction f = new SinFunction();
UnivariateRealIntegrator integrator = new TrapezoidIntegrator();
try {
// bad interval
integrator.integrate(f, 1, -1);
fail("Expecting IllegalArgumentException - bad interval");
} catch (IllegalArgumentException ex) {
// expected
}
try {
// bad iteration limits
integrator.setMinimalIterationCount(5);
integrator.setMaximalIterationCount(4);
integrator.integrate(f, -1, 1);
fail("Expecting IllegalArgumentException - bad iteration limits");
} catch (IllegalArgumentException ex) {
// expected
}
try {
// bad iteration limits
integrator.setMinimalIterationCount(10);
integrator.setMaximalIterationCount(99);
integrator.integrate(f, -1, 1);
fail("Expecting IllegalArgumentException - bad iteration limits");
} catch (IllegalArgumentException ex) {
// expected
}
}
}