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 package org.apache.commons.math.analysis.integration; 018 019 import org.apache.commons.math.MathException; 020 import org.apache.commons.math.analysis.QuinticFunction; 021 import org.apache.commons.math.analysis.SinFunction; 022 import org.apache.commons.math.analysis.UnivariateRealFunction; 023 024 import junit.framework.TestCase; 025 026 /** 027 * Testcase for Romberg integrator. 028 * <p> 029 * Romberg algorithm is very fast for good behavior integrand. Test runs 030 * show that for a default relative accuracy of 1E-6, it generally takes 031 * takes less than 5 iterations for the integral to converge. 032 * 033 * @version $Revision: 799857 $ $Date: 2009-08-01 09:07:12 -0400 (Sat, 01 Aug 2009) $ 034 */ 035 public final class RombergIntegratorTest extends TestCase { 036 037 /** 038 * Test of integrator for the sine function. 039 */ 040 public void testSinFunction() throws MathException { 041 UnivariateRealFunction f = new SinFunction(); 042 UnivariateRealIntegrator integrator = new RombergIntegrator(); 043 double min, max, expected, result, tolerance; 044 045 min = 0; max = Math.PI; expected = 2; 046 tolerance = Math.abs(expected * integrator.getRelativeAccuracy()); 047 result = integrator.integrate(f, min, max); 048 assertEquals(expected, result, tolerance); 049 050 min = -Math.PI/3; max = 0; expected = -0.5; 051 tolerance = Math.abs(expected * integrator.getRelativeAccuracy()); 052 result = integrator.integrate(f, min, max); 053 assertEquals(expected, result, tolerance); 054 } 055 056 /** 057 * Test of integrator for the quintic function. 058 */ 059 public void testQuinticFunction() throws MathException { 060 UnivariateRealFunction f = new QuinticFunction(); 061 UnivariateRealIntegrator integrator = new RombergIntegrator(); 062 double min, max, expected, result, tolerance; 063 064 min = 0; max = 1; expected = -1.0/48; 065 tolerance = Math.abs(expected * integrator.getRelativeAccuracy()); 066 result = integrator.integrate(f, min, max); 067 assertEquals(expected, result, tolerance); 068 069 min = 0; max = 0.5; expected = 11.0/768; 070 tolerance = Math.abs(expected * integrator.getRelativeAccuracy()); 071 result = integrator.integrate(f, min, max); 072 assertEquals(expected, result, tolerance); 073 074 min = -1; max = 4; expected = 2048/3.0 - 78 + 1.0/48; 075 tolerance = Math.abs(expected * integrator.getRelativeAccuracy()); 076 result = integrator.integrate(f, min, max); 077 assertEquals(expected, result, tolerance); 078 } 079 080 /** 081 * Test of parameters for the integrator. 082 */ 083 public void testParameters() throws Exception { 084 UnivariateRealFunction f = new SinFunction(); 085 UnivariateRealIntegrator integrator = new RombergIntegrator(); 086 087 try { 088 // bad interval 089 integrator.integrate(f, 1, -1); 090 fail("Expecting IllegalArgumentException - bad interval"); 091 } catch (IllegalArgumentException ex) { 092 // expected 093 } 094 try { 095 // bad iteration limits 096 integrator.setMinimalIterationCount(5); 097 integrator.setMaximalIterationCount(4); 098 integrator.integrate(f, -1, 1); 099 fail("Expecting IllegalArgumentException - bad iteration limits"); 100 } catch (IllegalArgumentException ex) { 101 // expected 102 } 103 try { 104 // bad iteration limits 105 integrator.setMinimalIterationCount(10); 106 integrator.setMaximalIterationCount(50); 107 integrator.integrate(f, -1, 1); 108 fail("Expecting IllegalArgumentException - bad iteration limits"); 109 } catch (IllegalArgumentException ex) { 110 // expected 111 } 112 } 113 }