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Java example source code file (LinearObjectiveFunction.java)

This example Java source code file (LinearObjectiveFunction.java) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Learn more about this Java project at its project page.

Java - Java tags/keywords

arrayrealvector, classnotfoundexception, deprecated, ioexception, linearobjectivefunction, override, realvector, serializable

The LinearObjectiveFunction.java Java example source code

/*
 * 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.math3.optimization.linear;

import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.Serializable;

import org.apache.commons.math3.linear.MatrixUtils;
import org.apache.commons.math3.linear.RealVector;
import org.apache.commons.math3.linear.ArrayRealVector;

/**
 * An objective function for a linear optimization problem.
 * <p>
 * A linear objective function has one the form:
 * <pre>
 * c<sub>1x1 + ... cnxn + d
 * </pre>
 * The c<sub>i and d are the coefficients of the equation,
 * the x<sub>i are the coordinates of the current point.
 * </p>
 * @deprecated As of 3.1 (to be removed in 4.0).
 * @since 2.0
 */
@Deprecated
public class LinearObjectiveFunction implements Serializable {

    /** Serializable version identifier. */
    private static final long serialVersionUID = -4531815507568396090L;

    /** Coefficients of the constraint (c<sub>i). */
    private final transient RealVector coefficients;

    /** Constant term of the linear equation. */
    private final double constantTerm;

    /**
     * @param coefficients The coefficients for the linear equation being optimized
     * @param constantTerm The constant term of the linear equation
     */
    public LinearObjectiveFunction(double[] coefficients, double constantTerm) {
        this(new ArrayRealVector(coefficients), constantTerm);
    }

    /**
     * @param coefficients The coefficients for the linear equation being optimized
     * @param constantTerm The constant term of the linear equation
     */
    public LinearObjectiveFunction(RealVector coefficients, double constantTerm) {
        this.coefficients = coefficients;
        this.constantTerm = constantTerm;
    }

    /**
     * Get the coefficients of the linear equation being optimized.
     * @return coefficients of the linear equation being optimized
     */
    public RealVector getCoefficients() {
        return coefficients;
    }

    /**
     * Get the constant of the linear equation being optimized.
     * @return constant of the linear equation being optimized
     */
    public double getConstantTerm() {
        return constantTerm;
    }

    /**
     * Compute the value of the linear equation at the current point
     * @param point point at which linear equation must be evaluated
     * @return value of the linear equation at the current point
     */
    public double getValue(final double[] point) {
        return coefficients.dotProduct(new ArrayRealVector(point, false)) + constantTerm;
    }

    /**
     * Compute the value of the linear equation at the current point
     * @param point point at which linear equation must be evaluated
     * @return value of the linear equation at the current point
     */
    public double getValue(final RealVector point) {
        return coefficients.dotProduct(point) + constantTerm;
    }

    /** {@inheritDoc} */
    @Override
    public boolean equals(Object other) {

      if (this == other) {
        return true;
      }

      if (other instanceof LinearObjectiveFunction) {
          LinearObjectiveFunction rhs = (LinearObjectiveFunction) other;
          return (constantTerm == rhs.constantTerm) && coefficients.equals(rhs.coefficients);
      }

      return false;
    }

    /** {@inheritDoc} */
    @Override
    public int hashCode() {
        return Double.valueOf(constantTerm).hashCode() ^ coefficients.hashCode();
    }

    /**
     * Serialize the instance.
     * @param oos stream where object should be written
     * @throws IOException if object cannot be written to stream
     */
    private void writeObject(ObjectOutputStream oos)
        throws IOException {
        oos.defaultWriteObject();
        MatrixUtils.serializeRealVector(coefficients, oos);
    }

    /**
     * Deserialize the instance.
     * @param ois stream from which the object should be read
     * @throws ClassNotFoundException if a class in the stream cannot be found
     * @throws IOException if object cannot be read from the stream
     */
    private void readObject(ObjectInputStream ois)
      throws ClassNotFoundException, IOException {
        ois.defaultReadObject();
        MatrixUtils.deserializeRealVector(this, "coefficients", ois);
    }

}

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