001 /*
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements. See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License. You may obtain a copy of the License at
008 *
009 * http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017
018 package org.apache.commons.math3.optimization.linear;
019
020 import java.io.IOException;
021 import java.io.ObjectInputStream;
022 import java.io.ObjectOutputStream;
023 import java.io.Serializable;
024
025 import org.apache.commons.math3.linear.MatrixUtils;
026 import org.apache.commons.math3.linear.RealVector;
027 import org.apache.commons.math3.linear.ArrayRealVector;
028
029 /**
030 * An objective function for a linear optimization problem.
031 * <p>
032 * A linear objective function has one the form:
033 * <pre>
034 * c<sub>1</sub>x<sub>1</sub> + ... c<sub>n</sub>x<sub>n</sub> + d
035 * </pre>
036 * The c<sub>i</sub> and d are the coefficients of the equation,
037 * the x<sub>i</sub> are the coordinates of the current point.
038 * </p>
039 * @version $Id: LinearObjectiveFunction.java 1422230 2012-12-15 12:11:13Z erans $
040 * @deprecated As of 3.1 (to be removed in 4.0).
041 * @since 2.0
042 */
043 @Deprecated
044 public class LinearObjectiveFunction implements Serializable {
045
046 /** Serializable version identifier. */
047 private static final long serialVersionUID = -4531815507568396090L;
048
049 /** Coefficients of the constraint (c<sub>i</sub>). */
050 private final transient RealVector coefficients;
051
052 /** Constant term of the linear equation. */
053 private final double constantTerm;
054
055 /**
056 * @param coefficients The coefficients for the linear equation being optimized
057 * @param constantTerm The constant term of the linear equation
058 */
059 public LinearObjectiveFunction(double[] coefficients, double constantTerm) {
060 this(new ArrayRealVector(coefficients), constantTerm);
061 }
062
063 /**
064 * @param coefficients The coefficients for the linear equation being optimized
065 * @param constantTerm The constant term of the linear equation
066 */
067 public LinearObjectiveFunction(RealVector coefficients, double constantTerm) {
068 this.coefficients = coefficients;
069 this.constantTerm = constantTerm;
070 }
071
072 /**
073 * Get the coefficients of the linear equation being optimized.
074 * @return coefficients of the linear equation being optimized
075 */
076 public RealVector getCoefficients() {
077 return coefficients;
078 }
079
080 /**
081 * Get the constant of the linear equation being optimized.
082 * @return constant of the linear equation being optimized
083 */
084 public double getConstantTerm() {
085 return constantTerm;
086 }
087
088 /**
089 * Compute the value of the linear equation at the current point
090 * @param point point at which linear equation must be evaluated
091 * @return value of the linear equation at the current point
092 */
093 public double getValue(final double[] point) {
094 return coefficients.dotProduct(new ArrayRealVector(point, false)) + constantTerm;
095 }
096
097 /**
098 * Compute the value of the linear equation at the current point
099 * @param point point at which linear equation must be evaluated
100 * @return value of the linear equation at the current point
101 */
102 public double getValue(final RealVector point) {
103 return coefficients.dotProduct(point) + constantTerm;
104 }
105
106 @Override
107 public boolean equals(Object other) {
108
109 if (this == other) {
110 return true;
111 }
112
113 if (other instanceof LinearObjectiveFunction) {
114 LinearObjectiveFunction rhs = (LinearObjectiveFunction) other;
115 return (constantTerm == rhs.constantTerm) && coefficients.equals(rhs.coefficients);
116 }
117
118 return false;
119 }
120
121 @Override
122 public int hashCode() {
123 return Double.valueOf(constantTerm).hashCode() ^ coefficients.hashCode();
124 }
125
126 /**
127 * Serialize the instance.
128 * @param oos stream where object should be written
129 * @throws IOException if object cannot be written to stream
130 */
131 private void writeObject(ObjectOutputStream oos)
132 throws IOException {
133 oos.defaultWriteObject();
134 MatrixUtils.serializeRealVector(coefficients, oos);
135 }
136
137 /**
138 * Deserialize the instance.
139 * @param ois stream from which the object should be read
140 * @throws ClassNotFoundException if a class in the stream cannot be found
141 * @throws IOException if object cannot be read from the stream
142 */
143 private void readObject(ObjectInputStream ois)
144 throws ClassNotFoundException, IOException {
145 ois.defaultReadObject();
146 MatrixUtils.deserializeRealVector(this, "coefficients", ois);
147 }
148
149 }