| /* |
| * 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.math4.legacy.optim.linear; |
| |
| import org.apache.commons.math4.legacy.analysis.MultivariateFunction; |
| import org.apache.commons.math4.legacy.linear.ArrayRealVector; |
| import org.apache.commons.math4.legacy.linear.MatrixUtils; |
| import org.apache.commons.math4.legacy.linear.RealVector; |
| import org.apache.commons.math4.legacy.optim.OptimizationData; |
| |
| /** |
| * An objective function for a linear optimization problem. |
| * <p> |
| * A linear objective function has one the form: |
| * <div style="white-space: pre"><code> |
| * c<sub>1</sub>x<sub>1</sub> + ... c<sub>n</sub>x<sub>n</sub> + d |
| * </code></div> |
| * 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. |
| * |
| * @since 2.0 |
| */ |
| public class LinearObjectiveFunction |
| implements MultivariateFunction, |
| OptimizationData { |
| /** Coefficients of the linear equation (c<sub>i</sub>). */ |
| private final transient RealVector coefficients; |
| /** Constant term of the linear equation. */ |
| private final double constantTerm; |
| |
| /** |
| * @param coefficients Coefficients for the linear equation being optimized. |
| * @param constantTerm Constant term of the linear equation. |
| */ |
| public LinearObjectiveFunction(double[] coefficients, double constantTerm) { |
| this(new ArrayRealVector(coefficients), constantTerm); |
| } |
| |
| /** |
| * @param coefficients Coefficients for the linear equation being optimized. |
| * @param constantTerm Constant term of the linear equation. |
| */ |
| public LinearObjectiveFunction(RealVector coefficients, double constantTerm) { |
| this.coefficients = coefficients; |
| this.constantTerm = constantTerm; |
| } |
| |
| /** |
| * Gets the coefficients of the linear equation being optimized. |
| * |
| * @return coefficients of the linear equation being optimized. |
| */ |
| public RealVector getCoefficients() { |
| return coefficients; |
| } |
| |
| /** |
| * Gets the constant of the linear equation being optimized. |
| * |
| * @return constant of the linear equation being optimized. |
| */ |
| public double getConstantTerm() { |
| return constantTerm; |
| } |
| |
| /** |
| * Computes the value of the linear equation at the current point. |
| * |
| * @param point Point at which linear equation must be evaluated. |
| * @return the value of the linear equation at the current point. |
| */ |
| @Override |
| public double value(final double[] point) { |
| return value(new ArrayRealVector(point, false)); |
| } |
| |
| /** |
| * Computes the value of the linear equation at the current point. |
| * |
| * @param point Point at which linear equation must be evaluated. |
| * @return the value of the linear equation at the current point. |
| */ |
| public double value(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(); |
| } |
| } |