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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.io.IOException;
21  import java.io.ObjectInputStream;
22  import java.io.ObjectOutputStream;
23  import java.io.Serializable;
24  
25  import org.apache.commons.math3.linear.MatrixUtils;
26  import org.apache.commons.math3.linear.RealVector;
27  import org.apache.commons.math3.linear.ArrayRealVector;
28  
29  /**
30   * An objective function for a linear optimization problem.
31   * <p>
32   * A linear objective function has one the form:
33   * <pre>
34   * c<sub>1</sub>x<sub>1</sub> + ... c<sub>n</sub>x<sub>n</sub> + d
35   * </pre>
36   * The c<sub>i</sub> and d are the coefficients of the equation,
37   * the x<sub>i</sub> are the coordinates of the current point.
38   * </p>
39   * @deprecated As of 3.1 (to be removed in 4.0).
40   * @since 2.0
41   */
42  @Deprecated
43  public class LinearObjectiveFunction implements Serializable {
44  
45      /** Serializable version identifier. */
46      private static final long serialVersionUID = -4531815507568396090L;
47  
48      /** Coefficients of the constraint (c<sub>i</sub>). */
49      private final transient RealVector coefficients;
50  
51      /** Constant term of the linear equation. */
52      private final double constantTerm;
53  
54      /**
55       * @param coefficients The coefficients for the linear equation being optimized
56       * @param constantTerm The constant term of the linear equation
57       */
58      public LinearObjectiveFunction(double[] coefficients, double constantTerm) {
59          this(new ArrayRealVector(coefficients), constantTerm);
60      }
61  
62      /**
63       * @param coefficients The coefficients for the linear equation being optimized
64       * @param constantTerm The constant term of the linear equation
65       */
66      public LinearObjectiveFunction(RealVector coefficients, double constantTerm) {
67          this.coefficients = coefficients;
68          this.constantTerm = constantTerm;
69      }
70  
71      /**
72       * Get the coefficients of the linear equation being optimized.
73       * @return coefficients of the linear equation being optimized
74       */
75      public RealVector getCoefficients() {
76          return coefficients;
77      }
78  
79      /**
80       * Get the constant of the linear equation being optimized.
81       * @return constant of the linear equation being optimized
82       */
83      public double getConstantTerm() {
84          return constantTerm;
85      }
86  
87      /**
88       * Compute the value of the linear equation at the current point
89       * @param point point at which linear equation must be evaluated
90       * @return value of the linear equation at the current point
91       */
92      public double getValue(final double[] point) {
93          return coefficients.dotProduct(new ArrayRealVector(point, false)) + constantTerm;
94      }
95  
96      /**
97       * Compute the value of the linear equation at the current point
98       * @param point point at which linear equation must be evaluated
99       * @return value of the linear equation at the current point
100      */
101     public double getValue(final RealVector point) {
102         return coefficients.dotProduct(point) + constantTerm;
103     }
104 
105     @Override
106     public boolean equals(Object other) {
107 
108       if (this == other) {
109         return true;
110       }
111 
112       if (other instanceof LinearObjectiveFunction) {
113           LinearObjectiveFunction rhs = (LinearObjectiveFunction) other;
114           return (constantTerm == rhs.constantTerm) && coefficients.equals(rhs.coefficients);
115       }
116 
117       return false;
118     }
119 
120     @Override
121     public int hashCode() {
122         return Double.valueOf(constantTerm).hashCode() ^ coefficients.hashCode();
123     }
124 
125     /**
126      * Serialize the instance.
127      * @param oos stream where object should be written
128      * @throws IOException if object cannot be written to stream
129      */
130     private void writeObject(ObjectOutputStream oos)
131         throws IOException {
132         oos.defaultWriteObject();
133         MatrixUtils.serializeRealVector(coefficients, oos);
134     }
135 
136     /**
137      * Deserialize the instance.
138      * @param ois stream from which the object should be read
139      * @throws ClassNotFoundException if a class in the stream cannot be found
140      * @throws IOException if object cannot be read from the stream
141      */
142     private void readObject(ObjectInputStream ois)
143       throws ClassNotFoundException, IOException {
144         ois.defaultReadObject();
145         MatrixUtils.deserializeRealVector(this, "coefficients", ois);
146     }
147 
148 }