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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  /**
21   * Types of relationships between two cells in a Solver {@link LinearConstraint}.
22   * @version $Revision: 758920 $ $Date: 2009-03-26 19:25:30 -0400 (Thu, 26 Mar 2009) $
23   * @since 2.0
24   */
25  public enum Relationship {
26  
27      /** Equality relationship. */
28      EQ("="),
29  
30      /** Lesser than or equal relationship. */
31      LEQ("<="),
32  
33      /** Greater than or equal relationship. */
34      GEQ(">=");
35  
36      /** Display string for the relationship. */
37      private String stringValue;
38  
39      /** Simple constructor.
40       * @param stringValue display string for the relationship
41       */
42      private Relationship(String stringValue) {
43          this.stringValue = stringValue;
44      }
45  
46      /** {@inheritDoc} */
47      @Override
48      public String toString() {
49          return stringValue;
50      }
51  
52      /**
53       * Get the relationship obtained when multiplying all coefficients by -1.
54       * @return relationship obtained when multiplying all coefficients by -1
55       */
56      public Relationship oppositeRelationship() {
57          switch (this) {
58          case LEQ :
59              return GEQ;
60          case GEQ :
61              return LEQ;
62          default :
63              return EQ;
64          }
65      }
66  
67  }