001 /*
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements. See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License. You may obtain a copy of the License at
008 *
009 * http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017 package org.apache.commons.math;
018
019 /**
020 * Interface representing a <a href="http://mathworld.wolfram.com/Field.html">field</a>.
021 * <p>
022 * Classes implementing this interface will often be singletons.
023 * </p>
024 * @param <T> the type of the field elements
025 * @see FieldElement
026 * @version $Revision: 811685 $ $Date: 2009-09-05 13:36:48 -0400 (Sat, 05 Sep 2009) $
027 * @since 2.0
028 */
029 public interface Field<T> {
030
031 /** Get the additive identity of the field.
032 * <p>
033 * The additive identity is the element e<sub>0</sub> of the field such that
034 * for all elements a of the field, the equalities a + e<sub>0</sub> =
035 * e<sub>0</sub> + a = a hold.
036 * </p>
037 * @return additive identity of the field
038 */
039 T getZero();
040
041 /** Get the multiplicative identity of the field.
042 * <p>
043 * The multiplicative identity is the element e<sub>1</sub> of the field such that
044 * for all elements a of the field, the equalities a × e<sub>1</sub> =
045 * e<sub>1</sub> × a = a hold.
046 * </p>
047 * @return multiplicative identity of the field
048 */
049 T getOne();
050
051 }