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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  import org.apache.commons.math4.legacy.optim.OptimizationData;
20  
21  /**
22   * Pivot selection rule to the use for a Simplex solver.
23   *
24   * @since 3.3
25   */
26  public enum PivotSelectionRule implements OptimizationData {
27      /**
28       * The classical rule, the variable with the most negative coefficient
29       * in the objective function row will be chosen as entering variable.
30       */
31      DANTZIG,
32      /**
33       * The first variable with a negative coefficient in the objective function
34       * row will be chosen as entering variable. This rule guarantees to prevent
35       * cycles, but may take longer to find an optimal solution.
36       */
37      BLAND
38  }