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
018 package org.apache.commons.math.optimization.linear;
019
020 /**
021 * Types of relationships between two cells in a Solver {@link LinearConstraint}.
022 * @version $Revision: 1003886 $ $Date: 2010-10-02 23:04:44 +0200 (sam. 02 oct. 2010) $
023 * @since 2.0
024 */
025 public enum Relationship {
026
027 /** Equality relationship. */
028 EQ("="),
029
030 /** Lesser than or equal relationship. */
031 LEQ("<="),
032
033 /** Greater than or equal relationship. */
034 GEQ(">=");
035
036 /** Display string for the relationship. */
037 private final String stringValue;
038
039 /** Simple constructor.
040 * @param stringValue display string for the relationship
041 */
042 private Relationship(String stringValue) {
043 this.stringValue = stringValue;
044 }
045
046 /** {@inheritDoc} */
047 @Override
048 public String toString() {
049 return stringValue;
050 }
051
052 /**
053 * Get the relationship obtained when multiplying all coefficients by -1.
054 * @return relationship obtained when multiplying all coefficients by -1
055 */
056 public Relationship oppositeRelationship() {
057 switch (this) {
058 case LEQ :
059 return GEQ;
060 case GEQ :
061 return LEQ;
062 default :
063 return EQ;
064 }
065 }
066
067 }