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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  package org.apache.commons.math4.legacy.optim.linear;
18  
19  /**
20   * Types of relationships between two cells in a Solver {@link LinearConstraint}.
21   *
22   * @since 2.0
23   */
24  public enum Relationship {
25      /** Equality relationship. */
26      EQ("="),
27      /** Lesser than or equal relationship. */
28      LEQ("<="),
29      /** Greater than or equal relationship. */
30      GEQ(">=");
31  
32      /** Display string for the relationship. */
33      private final String stringValue;
34  
35      /**
36       * Simple constructor.
37       *
38       * @param stringValue Display string for the relationship.
39       */
40      Relationship(String stringValue) {
41          this.stringValue = stringValue;
42      }
43  
44      /** {@inheritDoc} */
45      @Override
46      public String toString() {
47          return stringValue;
48      }
49  
50      /**
51       * Gets the relationship obtained when multiplying all coefficients by -1.
52       *
53       * @return the opposite relationship.
54       */
55      public Relationship oppositeRelationship() {
56          switch (this) {
57          case LEQ :
58              return GEQ;
59          case GEQ :
60              return LEQ;
61          default :
62              return EQ;
63          }
64      }
65  }