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 */
017package org.apache.commons.math3.ml.distance;
018
019import java.io.Serializable;
020
021import org.apache.commons.math3.exception.DimensionMismatchException;
022
023/**
024 * Interface for distance measures of n-dimensional vectors.
025 *
026 * @since 3.2
027 */
028public interface DistanceMeasure extends Serializable {
029
030    /**
031     * Compute the distance between two n-dimensional vectors.
032     * <p>
033     * The two vectors are required to have the same dimension.
034     *
035     * @param a the first vector
036     * @param b the second vector
037     * @return the distance between the two vectors
038     * @throws DimensionMismatchException if the array lengths differ.
039     */
040    double compute(double[] a, double[] b) throws DimensionMismatchException;
041}