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Java example source code file (UnivariateOptimizer.java)

This example Java source code file (UnivariateOptimizer.java) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Learn more about this Java project at its project page.

Java - Java tags/keywords

baseoptimizer, goaltype, optimizationdata, override, searchinterval, toomanyevaluationsexception, univariatefunction, univariateobjectivefunction, univariateoptimizer, univariatepointvaluepair

The UnivariateOptimizer.java Java example source code

/*
 * 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.optim.univariate;

import org.apache.commons.math3.analysis.UnivariateFunction;
import org.apache.commons.math3.optim.BaseOptimizer;
import org.apache.commons.math3.optim.OptimizationData;
import org.apache.commons.math3.optim.nonlinear.scalar.GoalType;
import org.apache.commons.math3.optim.ConvergenceChecker;
import org.apache.commons.math3.exception.TooManyEvaluationsException;

/**
 * Base class for a univariate scalar function optimizer.
 *
 * @since 3.1
 */
public abstract class UnivariateOptimizer
    extends BaseOptimizer<UnivariatePointValuePair> {
    /** Objective function. */
    private UnivariateFunction function;
    /** Type of optimization. */
    private GoalType goal;
    /** Initial guess. */
    private double start;
    /** Lower bound. */
    private double min;
    /** Upper bound. */
    private double max;

    /**
     * @param checker Convergence checker.
     */
    protected UnivariateOptimizer(ConvergenceChecker<UnivariatePointValuePair> checker) {
        super(checker);
    }

    /**
     * {@inheritDoc}
     *
     * @param optData Optimization data. In addition to those documented in
     * {@link BaseOptimizer#parseOptimizationData(OptimizationData[])
     * BaseOptimizer}, this method will register the following data:
     * <ul>
     *  <li>{@link GoalType}
     *  <li>{@link SearchInterval}
     *  <li>{@link UnivariateObjectiveFunction}
     * </ul>
     * @return {@inheritDoc}
     * @throws TooManyEvaluationsException if the maximal number of
     * evaluations is exceeded.
     */
    @Override
    public UnivariatePointValuePair optimize(OptimizationData... optData)
        throws TooManyEvaluationsException {
        // Perform computation.
        return super.optimize(optData);
    }

    /**
     * @return the optimization type.
     */
    public GoalType getGoalType() {
        return goal;
    }

    /**
     * Scans the list of (required and optional) optimization data that
     * characterize the problem.
     *
     * @param optData Optimization data.
     * The following data will be looked for:
     * <ul>
     *  <li>{@link GoalType}
     *  <li>{@link SearchInterval}
     *  <li>{@link UnivariateObjectiveFunction}
     * </ul>
     */
    @Override
    protected void parseOptimizationData(OptimizationData... optData) {
        // Allow base class to register its own data.
        super.parseOptimizationData(optData);

        // The existing values (as set by the previous call) are reused if
        // not provided in the argument list.
        for (OptimizationData data : optData) {
            if (data instanceof SearchInterval) {
                final SearchInterval interval = (SearchInterval) data;
                min = interval.getMin();
                max = interval.getMax();
                start = interval.getStartValue();
                continue;
            }
            if (data instanceof UnivariateObjectiveFunction) {
                function = ((UnivariateObjectiveFunction) data).getObjectiveFunction();
                continue;
            }
            if (data instanceof GoalType) {
                goal = (GoalType) data;
                continue;
            }
        }
    }

    /**
     * @return the initial guess.
     */
    public double getStartValue() {
        return start;
    }
    /**
     * @return the lower bounds.
     */
    public double getMin() {
        return min;
    }
    /**
     * @return the upper bounds.
     */
    public double getMax() {
        return max;
    }

    /**
     * Computes the objective function value.
     * This method <em>must be called by subclasses to enforce the
     * evaluation counter limit.
     *
     * @param x Point at which the objective function must be evaluated.
     * @return the objective function value at the specified point.
     * @throws TooManyEvaluationsException if the maximal number of
     * evaluations is exceeded.
     */
    protected double computeObjectiveValue(double x) {
        super.incrementEvaluationCount();
        return function.value(x);
    }
}

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