diff options
Diffstat (limited to 'src/main/java/org/apache/commons/math3/analysis/solvers/BisectionSolver.java')
-rw-r--r-- | src/main/java/org/apache/commons/math3/analysis/solvers/BisectionSolver.java | 91 |
1 files changed, 91 insertions, 0 deletions
diff --git a/src/main/java/org/apache/commons/math3/analysis/solvers/BisectionSolver.java b/src/main/java/org/apache/commons/math3/analysis/solvers/BisectionSolver.java new file mode 100644 index 0000000..49f4057 --- /dev/null +++ b/src/main/java/org/apache/commons/math3/analysis/solvers/BisectionSolver.java @@ -0,0 +1,91 @@ +/* + * 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.math3.analysis.solvers; + +import org.apache.commons.math3.util.FastMath; +import org.apache.commons.math3.exception.TooManyEvaluationsException; + +/** + * Implements the <a href="http://mathworld.wolfram.com/Bisection.html"> + * bisection algorithm</a> for finding zeros of univariate real functions. + * <p> + * The function should be continuous but not necessarily smooth.</p> + * + */ +public class BisectionSolver extends AbstractUnivariateSolver { + /** Default absolute accuracy. */ + private static final double DEFAULT_ABSOLUTE_ACCURACY = 1e-6; + + /** + * Construct a solver with default accuracy (1e-6). + */ + public BisectionSolver() { + this(DEFAULT_ABSOLUTE_ACCURACY); + } + /** + * Construct a solver. + * + * @param absoluteAccuracy Absolute accuracy. + */ + public BisectionSolver(double absoluteAccuracy) { + super(absoluteAccuracy); + } + /** + * Construct a solver. + * + * @param relativeAccuracy Relative accuracy. + * @param absoluteAccuracy Absolute accuracy. + */ + public BisectionSolver(double relativeAccuracy, + double absoluteAccuracy) { + super(relativeAccuracy, absoluteAccuracy); + } + + /** + * {@inheritDoc} + */ + @Override + protected double doSolve() + throws TooManyEvaluationsException { + double min = getMin(); + double max = getMax(); + verifyInterval(min, max); + final double absoluteAccuracy = getAbsoluteAccuracy(); + double m; + double fm; + double fmin; + + while (true) { + m = UnivariateSolverUtils.midpoint(min, max); + fmin = computeObjectiveValue(min); + fm = computeObjectiveValue(m); + + if (fm * fmin > 0) { + // max and m bracket the root. + min = m; + } else { + // min and m bracket the root. + max = m; + } + + if (FastMath.abs(max - min) <= absoluteAccuracy) { + m = UnivariateSolverUtils.midpoint(min, max); + return m; + } + } + } +} |