MathUtil.java
/*
* Copyright (c) 2017, WSO2 Inc. (http://www.wso2.org) All Rights Reserved.
*
* WSO2 Inc. licenses this file to you under the Apache License,
* Version 2.0 (the "License"); you may not use this file except
* in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing,
* software distributed under the License is distributed on an
* "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
* KIND, either express or implied. See the License for the
* specific language governing permissions and limitations
* under the License.
*/
package org.wso2.extension.siddhi.execution.streamingml.util;
/**
* Special mathematical functions used in the ML algorithms.
*/
public class MathUtil {
/**
* Dot product of two 'double' vectors.
*
* @param vector1 vector 1
* @param vector2 vector 2
* @return the dot product.
*/
public static double dot(double[] vector1, double[] vector2) {
if (vector1.length != vector2.length) {
throw new IllegalArgumentException("The dimensions have to be equal!");
}
double sum = 0;
for (int i = 0; i < vector1.length; i++) {
sum += vector1[i] * vector2[i];
}
return sum;
}
/**
* finds the euclidean distance between two input points of equal dimension
* @param point1 input point one
* @param point2 input point two
* @return euclidean distance between point1 and point2
*/
public static double euclideanDistance(double[] point1, double[] point2) {
double sum = 0.0;
int dimensionality = point1.length;
for (int i = 0; i < dimensionality; i++) {
sum += Math.pow((point1[i] - point2[i]), 2);
}
double dist = Math.sqrt(sum);
dist = Math.round(dist * 10000.0) / 10000.0;
return dist;
}
}