| /* |
| * 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. |
| * <p>This base class handles the boilerplate methods associated to thresholds |
| * settings and iterations counters.</p> |
| * @version $Revision: 925812 $ $Date: 2010-03-21 16:49:31 +0100 (dim. 21 mars 2010) $ |
| * @since 2.0 |
| * |
| */ |
| public abstract class AbstractLinearOptimizer implements LinearOptimizer { |
| |
| /** Default maximal number of iterations allowed. */ |
| public static final int DEFAULT_MAX_ITERATIONS = 100; |
| |
| /** |
| * Linear objective function. |
| * @since 2.1 |
| */ |
| protected LinearObjectiveFunction function; |
| |
| /** |
| * Linear constraints. |
| * @since 2.1 |
| */ |
| protected Collection<LinearConstraint> linearConstraints; |
| |
| /** |
| * Type of optimization goal: either {@link GoalType#MAXIMIZE} or {@link GoalType#MINIMIZE}. |
| * @since 2.1 |
| */ |
| protected GoalType goal; |
| |
| /** |
| * Whether to restrict the variables to non-negative values. |
| * @since 2.1 |
| */ |
| protected boolean nonNegative; |
| |
| /** Maximal number of iterations allowed. */ |
| private int maxIterations; |
| |
| /** Number of iterations already performed. */ |
| private int iterations; |
| |
| /** Simple constructor with default settings. |
| * <p>The maximal number of evaluation is set to its default value.</p> |
| */ |
| 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<LinearConstraint> constraints, |
| final GoalType goalType, final boolean restrictToNonNegative) |
| throws OptimizationException { |
| |
| // store linear problem characteristics |
| this.function = f; |
| this.linearConstraints = constraints; |
| this.goal = goalType; |
| this.nonNegative = 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 |
| */ |
| protected abstract RealPointValuePair doOptimize() |
| throws OptimizationException; |
| |
| } |