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The Math project is a library of lightweight, self-contained mathematics and statistics components addressing the most common practical problems not immediately available in the Java programming language or commons-lang.
/*
* 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.optimization.linear;
import java.util.Collection;
import org.apache.commons.math.MaxIterationsExceededException;
import org.apache.commons.math.optimization.GoalType;
import org.apache.commons.math.optimization.OptimizationException;
import org.apache.commons.math.optimization.RealPointValuePair;
/**
* Base class for implementing linear optimizers.
* This base class handles the boilerplate methods associated to thresholds
* settings and iterations counters.
* @version $Revision: 786466 $ $Date: 2009-06-19 08:03:14 -0400 (Fri, 19 Jun 2009) $
* @since 2.0
*
*/
public abstract class AbstractLinearOptimizer implements LinearOptimizer {
/** Default maximal number of iterations allowed. */
public static final int DEFAULT_MAX_ITERATIONS = 100;
/** Maximal number of iterations allowed. */
private int maxIterations;
/** Number of iterations already performed. */
private int iterations;
/** Linear objective function. */
protected LinearObjectiveFunction f;
/** Linear constraints. */
protected Collection constraints;
/** Type of optimization goal: either {@link GoalType#MAXIMIZE} or {@link GoalType#MINIMIZE}. */
protected GoalType goalType;
/** Whether to restrict the variables to non-negative values. */
protected boolean restrictToNonNegative;
/** Simple constructor with default settings.
* The maximal number of evaluation is set to its default value.
*/
protected AbstractLinearOptimizer() {
setMaxIterations(DEFAULT_MAX_ITERATIONS);
}
/** {@inheritDoc} */
public void setMaxIterations(int maxIterations) {
this.maxIterations = maxIterations;
}
/** {@inheritDoc} */
public int getMaxIterations() {
return maxIterations;
}
/** {@inheritDoc} */
public int getIterations() {
return iterations;
}
/** Increment the iterations counter by 1.
* @exception OptimizationException if the maximal number
* of iterations is exceeded
*/
protected void incrementIterationsCounter()
throws OptimizationException {
if (++iterations > maxIterations) {
throw new OptimizationException(new MaxIterationsExceededException(maxIterations));
}
}
/** {@inheritDoc} */
public RealPointValuePair optimize(final LinearObjectiveFunction f,
final Collection constraints,
final GoalType goalType, final boolean restrictToNonNegative)
throws OptimizationException {
// store linear problem characteristics
this.f = f;
this.constraints = constraints;
this.goalType = goalType;
this.restrictToNonNegative = restrictToNonNegative;
iterations = 0;
// solve the problem
return doOptimize();
}
/** Perform the bulk of optimization algorithm.
* @return the point/value pair giving the optimal value for objective function
* @exception OptimizationException if no solution fulfilling the constraints
* can be found in the allowed number of iterations
*/
abstract protected RealPointValuePair doOptimize()
throws OptimizationException;
}
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