

Java example source code file (UnitSphereRandomVectorGenerator.java)
The UnitSphereRandomVectorGenerator.java Java example source code/* * Licensed to the Apache Software Foundation (ASF) under one or more * contributor license agreements. See the NOTICE file distributed with * this work for additional information regarding copyright ownership. * The ASF 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/LICENSE2.0 * * 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.apache.commons.math3.random; import org.apache.commons.math3.util.FastMath; /** * Generate random vectors isotropically located on the surface of a sphere. * * @since 2.1 */ public class UnitSphereRandomVectorGenerator implements RandomVectorGenerator { /** * RNG used for generating the individual components of the vectors. */ private final RandomGenerator rand; /** * Space dimension. */ private final int dimension; /** * @param dimension Space dimension. * @param rand RNG for the individual components of the vectors. */ public UnitSphereRandomVectorGenerator(final int dimension, final RandomGenerator rand) { this.dimension = dimension; this.rand = rand; } /** * Create an object that will use a default RNG ({@link MersenneTwister}), * in order to generate the individual components. * * @param dimension Space dimension. */ public UnitSphereRandomVectorGenerator(final int dimension) { this(dimension, new MersenneTwister()); } /** {@inheritDoc} */ public double[] nextVector() { final double[] v = new double[dimension]; // See http://mathworld.wolfram.com/SpherePointPicking.html for example. // Pick a point by choosing a standard Gaussian for each element, and then // normalizing to unit length. double normSq = 0; for (int i = 0; i < dimension; i++) { final double comp = rand.nextGaussian(); v[i] = comp; normSq += comp * comp; } final double f = 1 / FastMath.sqrt(normSq); for (int i = 0; i < dimension; i++) { v[i] *= f; } return v; } } Other Java examples (source code examples)Here is a short list of links related to this Java UnitSphereRandomVectorGenerator.java source code file: 
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