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Diffstat (limited to 'src/main/java/org/apache/commons/math/analysis/solvers/BisectionSolver.java')
-rw-r--r-- | src/main/java/org/apache/commons/math/analysis/solvers/BisectionSolver.java | 133 |
1 files changed, 133 insertions, 0 deletions
diff --git a/src/main/java/org/apache/commons/math/analysis/solvers/BisectionSolver.java b/src/main/java/org/apache/commons/math/analysis/solvers/BisectionSolver.java new file mode 100644 index 0000000..c9d3a63 --- /dev/null +++ b/src/main/java/org/apache/commons/math/analysis/solvers/BisectionSolver.java @@ -0,0 +1,133 @@ +/* + * 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.solvers; + +import org.apache.commons.math.FunctionEvaluationException; +import org.apache.commons.math.MaxIterationsExceededException; +import org.apache.commons.math.analysis.UnivariateRealFunction; +import org.apache.commons.math.util.FastMath; + +/** + * 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> + * + * @version $Revision: 1070725 $ $Date: 2011-02-15 02:31:12 +0100 (mar. 15 févr. 2011) $ + */ +public class BisectionSolver extends UnivariateRealSolverImpl { + + /** + * Construct a solver for the given function. + * + * @param f function to solve. + * @deprecated as of 2.0 the function to solve is passed as an argument + * to the {@link #solve(UnivariateRealFunction, double, double)} or + * {@link UnivariateRealSolverImpl#solve(UnivariateRealFunction, double, double, double)} + * method. + */ + @Deprecated + public BisectionSolver(UnivariateRealFunction f) { + super(f, 100, 1E-6); + } + + /** + * Construct a solver. + * + */ + public BisectionSolver() { + super(100, 1E-6); + } + + /** {@inheritDoc} */ + @Deprecated + public double solve(double min, double max, double initial) + throws MaxIterationsExceededException, FunctionEvaluationException { + return solve(f, min, max); + } + + /** {@inheritDoc} */ + @Deprecated + public double solve(double min, double max) + throws MaxIterationsExceededException, FunctionEvaluationException { + return solve(f, min, max); + } + + /** + * {@inheritDoc} + * @deprecated in 2.2 (to be removed in 3.0). + */ + @Deprecated + public double solve(final UnivariateRealFunction f, double min, double max, double initial) + throws MaxIterationsExceededException, FunctionEvaluationException { + return solve(f, min, max); + } + + /** {@inheritDoc} */ + @Override + public double solve(int maxEval, final UnivariateRealFunction f, double min, double max, double initial) + throws MaxIterationsExceededException, FunctionEvaluationException { + return solve(maxEval, f, min, max); + } + + /** {@inheritDoc} */ + @Override + public double solve(int maxEval, final UnivariateRealFunction f, double min, double max) + throws MaxIterationsExceededException, FunctionEvaluationException { + setMaximalIterationCount(maxEval); + return solve(f, min, max); + } + + /** + * {@inheritDoc} + * @deprecated in 2.2 (to be removed in 3.0). + */ + @Deprecated + public double solve(final UnivariateRealFunction f, double min, double max) + throws MaxIterationsExceededException, FunctionEvaluationException { + + clearResult(); + verifyInterval(min,max); + double m; + double fm; + double fmin; + + int i = 0; + while (i < maximalIterationCount) { + m = UnivariateRealSolverUtils.midpoint(min, max); + fmin = f.value(min); + fm = f.value(m); + + if (fm * fmin > 0.0) { + // max and m bracket the root. + min = m; + } else { + // min and m bracket the root. + max = m; + } + + if (FastMath.abs(max - min) <= absoluteAccuracy) { + m = UnivariateRealSolverUtils.midpoint(min, max); + setResult(m, i); + return m; + } + ++i; + } + + throw new MaxIterationsExceededException(maximalIterationCount); + } +} |