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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.math3;
18  
19  /**
20   * Interface representing a <a href="http://mathworld.wolfram.com/Field.html">field</a>.
21   * <p>
22   * Classes implementing this interface will often be singletons.
23   * </p>
24   * @param <T> the type of the field elements
25   * @see FieldElement
26   * @since 2.0
27   */
28  public interface Field<T> {
29  
30      /** Get the additive identity of the field.
31       * <p>
32       * The additive identity is the element e<sub>0</sub> of the field such that
33       * for all elements a of the field, the equalities a + e<sub>0</sub> =
34       * e<sub>0</sub> + a = a hold.
35       * </p>
36       * @return additive identity of the field
37       */
38      T getZero();
39  
40      /** Get the multiplicative identity of the field.
41       * <p>
42       * The multiplicative identity is the element e<sub>1</sub> of the field such that
43       * for all elements a of the field, the equalities a &times; e<sub>1</sub> =
44       * e<sub>1</sub> &times; a = a hold.
45       * </p>
46       * @return multiplicative identity of the field
47       */
48      T getOne();
49  
50      /**
51       * Returns the runtime class of the FieldElement.
52       *
53       * @return The {@code Class} object that represents the runtime
54       *         class of this object.
55       */
56      Class<? extends FieldElement<T>> getRuntimeClass();
57  
58  }