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
018package org.apache.commons.math3.optimization.linear;
019
020import java.io.IOException;
021import java.io.ObjectInputStream;
022import java.io.ObjectOutputStream;
023import java.io.Serializable;
024
025import org.apache.commons.math3.linear.MatrixUtils;
026import org.apache.commons.math3.linear.RealVector;
027import 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
044public 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}