| /* |
| * 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.math.optimization.linear; |
| |
| import java.io.IOException; |
| import java.io.ObjectInputStream; |
| import java.io.ObjectOutputStream; |
| import java.io.Serializable; |
| |
| import org.apache.commons.math.linear.MatrixUtils; |
| import org.apache.commons.math.linear.RealVector; |
| import org.apache.commons.math.linear.ArrayRealVector; |
| |
| /** |
| * An objective function for a linear optimization problem. |
| * <p> |
| * A linear objective function has one the form: |
| * <pre> |
| * c<sub>1</sub>x<sub>1</sub> + ... c<sub>n</sub>x<sub>n</sub> + d |
| * </pre> |
| * The c<sub>i</sub> and d are the coefficients of the equation, |
| * the x<sub>i</sub> are the coordinates of the current point. |
| * </p> |
| * @version $Revision: 922713 $ $Date: 2010-03-14 02:26:13 +0100 (dim. 14 mars 2010) $ |
| * @since 2.0 |
| */ |
| public class LinearObjectiveFunction implements Serializable { |
| |
| /** Serializable version identifier. */ |
| private static final long serialVersionUID = -4531815507568396090L; |
| |
| /** Coefficients of the constraint (c<sub>i</sub>). */ |
| 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(point) + 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); |
| } |
| |
| } |