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1   /*
2    * Licensed to the Apache Software Foundation (ASF) under one or more
3    * contributor license agreements.  See the NOTICE file distributed with
4    * this work for additional information regarding copyright ownership.
5    * The ASF licenses this file to You under the Apache License, Version 2.0
6    * (the "License"); you may not use this file except in compliance with
7    * the License.  You may obtain a copy of the License at
8    *
9    *      http://www.apache.org/licenses/LICENSE-2.0
10   *
11   * Unless required by applicable law or agreed to in writing, software
12   * distributed under the License is distributed on an "AS IS" BASIS,
13   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14   * See the License for the specific language governing permissions and
15   * limitations under the License.
16   */
17  
18  package org.apache.commons.math3.optimization.linear;
19  
20  import java.util.Collection;
21  import java.util.Collections;
22  
23  import org.apache.commons.math3.exception.MathIllegalStateException;
24  import org.apache.commons.math3.exception.MaxCountExceededException;
25  import org.apache.commons.math3.optimization.GoalType;
26  import org.apache.commons.math3.optimization.PointValuePair;
27  
28  /**
29   * Base class for implementing linear optimizers.
30   * <p>
31   * This base class handles the boilerplate methods associated to thresholds
32   * settings and iterations counters.
33   *
34   * @version $Id: AbstractLinearOptimizer.java 1422230 2012-12-15 12:11:13Z erans $
35   * @deprecated As of 3.1 (to be removed in 4.0).
36   * @since 2.0
37   */
38  @Deprecated
39  public abstract class AbstractLinearOptimizer implements LinearOptimizer {
40  
41      /** Default maximal number of iterations allowed. */
42      public static final int DEFAULT_MAX_ITERATIONS = 100;
43  
44      /**
45       * Linear objective function.
46       * @since 2.1
47       */
48      private LinearObjectiveFunction function;
49  
50      /**
51       * Linear constraints.
52       * @since 2.1
53       */
54      private Collection<LinearConstraint> linearConstraints;
55  
56      /**
57       * Type of optimization goal: either {@link GoalType#MAXIMIZE} or {@link GoalType#MINIMIZE}.
58       * @since 2.1
59       */
60      private GoalType goal;
61  
62      /**
63       * Whether to restrict the variables to non-negative values.
64       * @since 2.1
65       */
66      private boolean nonNegative;
67  
68      /** Maximal number of iterations allowed. */
69      private int maxIterations;
70  
71      /** Number of iterations already performed. */
72      private int iterations;
73  
74      /**
75       * Simple constructor with default settings.
76       * <p>The maximal number of evaluation is set to its default value.</p>
77       */
78      protected AbstractLinearOptimizer() {
79          setMaxIterations(DEFAULT_MAX_ITERATIONS);
80      }
81  
82      /**
83       * @return {@code true} if the variables are restricted to non-negative values.
84       */
85      protected boolean restrictToNonNegative() {
86          return nonNegative;
87      }
88  
89      /**
90       * @return the optimization type.
91       */
92      protected GoalType getGoalType() {
93          return goal;
94      }
95  
96      /**
97       * @return the optimization type.
98       */
99      protected LinearObjectiveFunction getFunction() {
100         return function;
101     }
102 
103     /**
104      * @return the optimization type.
105      */
106     protected Collection<LinearConstraint> getConstraints() {
107         return Collections.unmodifiableCollection(linearConstraints);
108     }
109 
110     /** {@inheritDoc} */
111     public void setMaxIterations(int maxIterations) {
112         this.maxIterations = maxIterations;
113     }
114 
115     /** {@inheritDoc} */
116     public int getMaxIterations() {
117         return maxIterations;
118     }
119 
120     /** {@inheritDoc} */
121     public int getIterations() {
122         return iterations;
123     }
124 
125     /**
126      * Increment the iterations counter by 1.
127      * @exception MaxCountExceededException if the maximal number of iterations is exceeded
128      */
129     protected void incrementIterationsCounter()
130         throws MaxCountExceededException {
131         if (++iterations > maxIterations) {
132             throw new MaxCountExceededException(maxIterations);
133         }
134     }
135 
136     /** {@inheritDoc} */
137     public PointValuePair optimize(final LinearObjectiveFunction f,
138                                    final Collection<LinearConstraint> constraints,
139                                    final GoalType goalType, final boolean restrictToNonNegative)
140         throws MathIllegalStateException {
141 
142         // store linear problem characteristics
143         this.function          = f;
144         this.linearConstraints = constraints;
145         this.goal              = goalType;
146         this.nonNegative       = restrictToNonNegative;
147 
148         iterations  = 0;
149 
150         // solve the problem
151         return doOptimize();
152 
153     }
154 
155     /**
156      * Perform the bulk of optimization algorithm.
157      * @return the point/value pair giving the optimal value for objective function
158      * @exception MathIllegalStateException if no solution fulfilling the constraints
159      * can be found in the allowed number of iterations
160      */
161     protected abstract PointValuePair doOptimize() throws MathIllegalStateException;
162 
163 }