| /* |
| * 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/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.apache.sysds.runtime.util; |
| |
| import org.apache.commons.math3.distribution.PoissonDistribution; |
| import org.apache.commons.math3.random.SynchronizedRandomGenerator; |
| import org.apache.commons.math3.random.Well1024a; |
| |
| |
| /** |
| * Class that can generate a stream of random numbers from Poisson |
| * distribution with specified mean. |
| */ |
| |
| |
| public class PoissonPRNGenerator extends PRNGenerator |
| { |
| private PoissonDistribution _pdist = null; |
| private double _mean = Double.NaN; |
| private long seed; |
| |
| public PoissonPRNGenerator() { |
| // default mean and default seed |
| super(); |
| _mean = 1.0; |
| setup(_mean, seed); |
| } |
| |
| public PoissonPRNGenerator(double mean) { |
| // default seed |
| super(); |
| _mean = mean; |
| setup(_mean, seed); |
| } |
| |
| public void setup(double mean, long sd) { |
| seed = sd; |
| SynchronizedRandomGenerator srg = new SynchronizedRandomGenerator(new Well1024a()); |
| srg.setSeed(seed); |
| _pdist = new PoissonDistribution(srg, _mean, PoissonDistribution.DEFAULT_EPSILON, PoissonDistribution.DEFAULT_MAX_ITERATIONS); |
| } |
| |
| @Override |
| public void setSeed(long sd) { |
| setup(_mean, sd); |
| } |
| |
| public void setMean(double mean) { |
| setup(mean, seed); |
| } |
| |
| @Override |
| public double nextDouble() { |
| return _pdist.sample(); |
| } |
| } |