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.math;
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 * @version $Revision: 777521 $ $Date: 2009-05-22 09:48:21 -0400 (Fri, 22 May 2009) $
27 * @since 2.0
28 */
29 public interface Field<T> {
30
31 /** Get the additive identity of the field.
32 * <p>
33 * The additive identity is the element e<sub>0</sub> of the field such that
34 * for all elements a of the field, the equalities a + e<sub>0</sub> =
35 * e<sub>0</sub> + a = a hold.
36 * </p>
37 * @return additive identity of the field
38 */
39 T getZero();
40
41 /** Get the multiplicative identity of the field.
42 * <p>
43 * The multiplicative identity is the element e<sub>1</sub> of the field such that
44 * for all elements a of the field, the equalities a × e<sub>1</sub> =
45 * e<sub>1</sub> × a = a hold.
46 * </p>
47 * @return multiplicative identity of the field
48 */
49 T getOne();
50
51 }