1 /* 2 * Licensed to the Apache Software Foundation (ASF) under one or more 3 * contributor license agreements. See the NOTICE file distributed with 4 * this work for additional information regarding copyright ownership. 5 * The ASF licenses this file to You under the Apache License, Version 2.0 6 * (the "License"); you may not use this file except in compliance with 7 * the License. You may obtain a copy of the License at 8 * 9 * http://www.apache.org/licenses/LICENSE-2.0 10 * 11 * Unless required by applicable law or agreed to in writing, software 12 * distributed under the License is distributed on an "AS IS" BASIS, 13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 14 * See the License for the specific language governing permissions and 15 * limitations under the License. 16 */ 17 18 package org.apache.commons.math.optimization.linear; 19 20 import java.io.IOException; 21 import java.io.ObjectInputStream; 22 import java.io.ObjectOutputStream; 23 import java.io.Serializable; 24 25 import org.apache.commons.math.linear.MatrixUtils; 26 import org.apache.commons.math.linear.RealVector; 27 import org.apache.commons.math.linear.ArrayRealVector; 28 29 30 /** 31 * A linear constraint for a linear optimization problem. 32 * <p> 33 * A linear constraint has one of the forms: 34 * <ul> 35 * <li>c<sub>1</sub>x<sub>1</sub> + ... c<sub>n</sub>x<sub>n</sub> = v</li> 36 * <li>c<sub>1</sub>x<sub>1</sub> + ... c<sub>n</sub>x<sub>n</sub> <= v</li> 37 * <li>c<sub>1</sub>x<sub>1</sub> + ... c<sub>n</sub>x<sub>n</sub> >= v</li> 38 * <li>l<sub>1</sub>x<sub>1</sub> + ... l<sub>n</sub>x<sub>n</sub> + l<sub>cst</sub> = 39 * r<sub>1</sub>x<sub>1</sub> + ... r<sub>n</sub>x<sub>n</sub> + r<sub>cst</sub></li> 40 * <li>l<sub>1</sub>x<sub>1</sub> + ... l<sub>n</sub>x<sub>n</sub> + l<sub>cst</sub> <= 41 * r<sub>1</sub>x<sub>1</sub> + ... r<sub>n</sub>x<sub>n</sub> + r<sub>cst</sub></li> 42 * <li>l<sub>1</sub>x<sub>1</sub> + ... l<sub>n</sub>x<sub>n</sub> + l<sub>cst</sub> >= 43 * r<sub>1</sub>x<sub>1</sub> + ... r<sub>n</sub>x<sub>n</sub> + r<sub>cst</sub></li> 44 * </ul> 45 * The c<sub>i</sub>, l<sub>i</sub> or r<sub>i</sub> are the coefficients of the constraints, the x<sub>i</sub> 46 * are the coordinates of the current point and v is the value of the constraint. 47 * </p> 48 * @version $Revision: 922713 $ $Date: 2010-03-14 02:26:13 +0100 (dim. 14 mars 2010) $ 49 * @since 2.0 50 */ 51 public class LinearConstraint implements Serializable { 52 53 /** Serializable version identifier. */ 54 private static final long serialVersionUID = -764632794033034092L; 55 56 /** Coefficients of the constraint (left hand side). */ 57 private final transient RealVector coefficients; 58 59 /** Relationship between left and right hand sides (=, <=, >=). */ 60 private final Relationship relationship; 61 62 /** Value of the constraint (right hand side). */ 63 private final double value; 64 65 /** 66 * Build a constraint involving a single linear equation. 67 * <p> 68 * A linear constraint with a single linear equation has one of the forms: 69 * <ul> 70 * <li>c<sub>1</sub>x<sub>1</sub> + ... c<sub>n</sub>x<sub>n</sub> = v</li> 71 * <li>c<sub>1</sub>x<sub>1</sub> + ... c<sub>n</sub>x<sub>n</sub> <= v</li> 72 * <li>c<sub>1</sub>x<sub>1</sub> + ... c<sub>n</sub>x<sub>n</sub> >= v</li> 73 * </ul> 74 * </p> 75 * @param coefficients The coefficients of the constraint (left hand side) 76 * @param relationship The type of (in)equality used in the constraint 77 * @param value The value of the constraint (right hand side) 78 */ 79 public LinearConstraint(final double[] coefficients, final Relationship relationship, 80 final double value) { 81 this(new ArrayRealVector(coefficients), relationship, value); 82 } 83 84 /** 85 * Build a constraint involving a single linear equation. 86 * <p> 87 * A linear constraint with a single linear equation has one of the forms: 88 * <ul> 89 * <li>c<sub>1</sub>x<sub>1</sub> + ... c<sub>n</sub>x<sub>n</sub> = v</li> 90 * <li>c<sub>1</sub>x<sub>1</sub> + ... c<sub>n</sub>x<sub>n</sub> <= v</li> 91 * <li>c<sub>1</sub>x<sub>1</sub> + ... c<sub>n</sub>x<sub>n</sub> >= v</li> 92 * </ul> 93 * </p> 94 * @param coefficients The coefficients of the constraint (left hand side) 95 * @param relationship The type of (in)equality used in the constraint 96 * @param value The value of the constraint (right hand side) 97 */ 98 public LinearConstraint(final RealVector coefficients, final Relationship relationship, 99 final double value) { 100 this.coefficients = coefficients; 101 this.relationship = relationship; 102 this.value = value; 103 } 104 105 /** 106 * Build a constraint involving two linear equations. 107 * <p> 108 * A linear constraint with two linear equation has one of the forms: 109 * <ul> 110 * <li>l<sub>1</sub>x<sub>1</sub> + ... l<sub>n</sub>x<sub>n</sub> + l<sub>cst</sub> = 111 * r<sub>1</sub>x<sub>1</sub> + ... r<sub>n</sub>x<sub>n</sub> + r<sub>cst</sub></li> 112 * <li>l<sub>1</sub>x<sub>1</sub> + ... l<sub>n</sub>x<sub>n</sub> + l<sub>cst</sub> <= 113 * r<sub>1</sub>x<sub>1</sub> + ... r<sub>n</sub>x<sub>n</sub> + r<sub>cst</sub></li> 114 * <li>l<sub>1</sub>x<sub>1</sub> + ... l<sub>n</sub>x<sub>n</sub> + l<sub>cst</sub> >= 115 * r<sub>1</sub>x<sub>1</sub> + ... r<sub>n</sub>x<sub>n</sub> + r<sub>cst</sub></li> 116 * </ul> 117 * </p> 118 * @param lhsCoefficients The coefficients of the linear expression on the left hand side of the constraint 119 * @param lhsConstant The constant term of the linear expression on the left hand side of the constraint 120 * @param relationship The type of (in)equality used in the constraint 121 * @param rhsCoefficients The coefficients of the linear expression on the right hand side of the constraint 122 * @param rhsConstant The constant term of the linear expression on the right hand side of the constraint 123 */ 124 public LinearConstraint(final double[] lhsCoefficients, final double lhsConstant, 125 final Relationship relationship, 126 final double[] rhsCoefficients, final double rhsConstant) { 127 double[] sub = new double[lhsCoefficients.length]; 128 for (int i = 0; i < sub.length; ++i) { 129 sub[i] = lhsCoefficients[i] - rhsCoefficients[i]; 130 } 131 this.coefficients = new ArrayRealVector(sub, false); 132 this.relationship = relationship; 133 this.value = rhsConstant - lhsConstant; 134 } 135 136 /** 137 * Build a constraint involving two linear equations. 138 * <p> 139 * A linear constraint with two linear equation has one of the forms: 140 * <ul> 141 * <li>l<sub>1</sub>x<sub>1</sub> + ... l<sub>n</sub>x<sub>n</sub> + l<sub>cst</sub> = 142 * r<sub>1</sub>x<sub>1</sub> + ... r<sub>n</sub>x<sub>n</sub> + r<sub>cst</sub></li> 143 * <li>l<sub>1</sub>x<sub>1</sub> + ... l<sub>n</sub>x<sub>n</sub> + l<sub>cst</sub> <= 144 * r<sub>1</sub>x<sub>1</sub> + ... r<sub>n</sub>x<sub>n</sub> + r<sub>cst</sub></li> 145 * <li>l<sub>1</sub>x<sub>1</sub> + ... l<sub>n</sub>x<sub>n</sub> + l<sub>cst</sub> >= 146 * r<sub>1</sub>x<sub>1</sub> + ... r<sub>n</sub>x<sub>n</sub> + r<sub>cst</sub></li> 147 * </ul> 148 * </p> 149 * @param lhsCoefficients The coefficients of the linear expression on the left hand side of the constraint 150 * @param lhsConstant The constant term of the linear expression on the left hand side of the constraint 151 * @param relationship The type of (in)equality used in the constraint 152 * @param rhsCoefficients The coefficients of the linear expression on the right hand side of the constraint 153 * @param rhsConstant The constant term of the linear expression on the right hand side of the constraint 154 */ 155 public LinearConstraint(final RealVector lhsCoefficients, final double lhsConstant, 156 final Relationship relationship, 157 final RealVector rhsCoefficients, final double rhsConstant) { 158 this.coefficients = lhsCoefficients.subtract(rhsCoefficients); 159 this.relationship = relationship; 160 this.value = rhsConstant - lhsConstant; 161 } 162 163 /** 164 * Get the coefficients of the constraint (left hand side). 165 * @return coefficients of the constraint (left hand side) 166 */ 167 public RealVector getCoefficients() { 168 return coefficients; 169 } 170 171 /** 172 * Get the relationship between left and right hand sides. 173 * @return relationship between left and right hand sides 174 */ 175 public Relationship getRelationship() { 176 return relationship; 177 } 178 179 /** 180 * Get the value of the constraint (right hand side). 181 * @return value of the constraint (right hand side) 182 */ 183 public double getValue() { 184 return value; 185 } 186 187 /** {@inheritDoc} */ 188 @Override 189 public boolean equals(Object other) { 190 191 if (this == other) { 192 return true; 193 } 194 195 if (other instanceof LinearConstraint) { 196 LinearConstraint rhs = (LinearConstraint) other; 197 return (relationship == rhs.relationship) && 198 (value == rhs.value) && 199 coefficients.equals(rhs.coefficients); 200 } 201 return false; 202 } 203 204 /** {@inheritDoc} */ 205 @Override 206 public int hashCode() { 207 return relationship.hashCode() ^ 208 Double.valueOf(value).hashCode() ^ 209 coefficients.hashCode(); 210 } 211 212 /** Serialize the instance. 213 * @param oos stream where object should be written 214 * @throws IOException if object cannot be written to stream 215 */ 216 private void writeObject(ObjectOutputStream oos) 217 throws IOException { 218 oos.defaultWriteObject(); 219 MatrixUtils.serializeRealVector(coefficients, oos); 220 } 221 222 /** Deserialize the instance. 223 * @param ois stream from which the object should be read 224 * @throws ClassNotFoundException if a class in the stream cannot be found 225 * @throws IOException if object cannot be read from the stream 226 */ 227 private void readObject(ObjectInputStream ois) 228 throws ClassNotFoundException, IOException { 229 ois.defaultReadObject(); 230 MatrixUtils.deserializeRealVector(this, "coefficients", ois); 231 } 232 233 } 234
