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 package org.apache.commons.math3.optim.linear;
018
019 /**
020 * Types of relationships between two cells in a Solver {@link LinearConstraint}.
021 *
022 * @version $Id: Relationship.java 1416643 2012-12-03 19:37:14Z tn $
023 * @since 2.0
024 */
025 public enum Relationship {
026 /** Equality relationship. */
027 EQ("="),
028 /** Lesser than or equal relationship. */
029 LEQ("<="),
030 /** Greater than or equal relationship. */
031 GEQ(">=");
032
033 /** Display string for the relationship. */
034 private final String stringValue;
035
036 /**
037 * Simple constructor.
038 *
039 * @param stringValue Display string for the relationship.
040 */
041 private Relationship(String stringValue) {
042 this.stringValue = stringValue;
043 }
044
045 @Override
046 public String toString() {
047 return stringValue;
048 }
049
050 /**
051 * Gets the relationship obtained when multiplying all coefficients by -1.
052 *
053 * @return the opposite relationship.
054 */
055 public Relationship oppositeRelationship() {
056 switch (this) {
057 case LEQ :
058 return GEQ;
059 case GEQ :
060 return LEQ;
061 default :
062 return EQ;
063 }
064 }
065 }