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 */ 017 018 package org.apache.commons.math3.analysis.solvers; 019 020 /** 021 * Implements the <em>Pegasus</em> method for root-finding (approximating 022 * a zero of a univariate real function). It is a modified 023 * {@link RegulaFalsiSolver <em>Regula Falsi</em>} method. 024 * 025 * <p>Like the <em>Regula Falsi</em> method, convergence is guaranteed by 026 * maintaining a bracketed solution. The <em>Pegasus</em> method however, 027 * should converge much faster than the original <em>Regula Falsi</em> 028 * method. Furthermore, this implementation of the <em>Pegasus</em> method 029 * should not suffer from the same implementation issues as the <em>Regula 030 * Falsi</em> method, which may fail to convergence in certain cases. Also, 031 * the <em>Pegasus</em> method should converge faster than the 032 * {@link IllinoisSolver <em>Illinois</em>} method, another <em>Regula 033 * Falsi</em>-based method.</p> 034 * 035 * <p>The <em>Pegasus</em> method assumes that the function is continuous, 036 * but not necessarily smooth.</p> 037 * 038 * <p>Implementation based on the following article: M. Dowell and P. Jarratt, 039 * <em>The "Pegasus" method for computing the root of an equation</em>, 040 * BIT Numerical Mathematics, volume 12, number 4, pages 503-508, Springer, 041 * 1972.</p> 042 * 043 * @since 3.0 044 * @version $Id: PegasusSolver.java 1364387 2012-07-22 18:14:11Z tn $ 045 */ 046 public class PegasusSolver extends BaseSecantSolver { 047 048 /** Construct a solver with default accuracy (1e-6). */ 049 public PegasusSolver() { 050 super(DEFAULT_ABSOLUTE_ACCURACY, Method.PEGASUS); 051 } 052 053 /** 054 * Construct a solver. 055 * 056 * @param absoluteAccuracy Absolute accuracy. 057 */ 058 public PegasusSolver(final double absoluteAccuracy) { 059 super(absoluteAccuracy, Method.PEGASUS); 060 } 061 062 /** 063 * Construct a solver. 064 * 065 * @param relativeAccuracy Relative accuracy. 066 * @param absoluteAccuracy Absolute accuracy. 067 */ 068 public PegasusSolver(final double relativeAccuracy, 069 final double absoluteAccuracy) { 070 super(relativeAccuracy, absoluteAccuracy, Method.PEGASUS); 071 } 072 073 /** 074 * Construct a solver. 075 * 076 * @param relativeAccuracy Relative accuracy. 077 * @param absoluteAccuracy Absolute accuracy. 078 * @param functionValueAccuracy Maximum function value error. 079 */ 080 public PegasusSolver(final double relativeAccuracy, 081 final double absoluteAccuracy, 082 final double functionValueAccuracy) { 083 super(relativeAccuracy, absoluteAccuracy, functionValueAccuracy, Method.PEGASUS); 084 } 085 }