| /* |
| * 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.commons.rng.examples.sampling; |
| |
| import org.apache.commons.rng.UniformRandomProvider; |
| import org.apache.commons.rng.simple.RandomSource; |
| import org.apache.commons.rng.sampling.distribution.ZigguratNormalizedGaussianSampler; |
| import org.apache.commons.rng.sampling.distribution.MarsagliaNormalizedGaussianSampler; |
| import org.apache.commons.rng.sampling.distribution.BoxMullerNormalizedGaussianSampler; |
| import org.apache.commons.rng.sampling.distribution.ContinuousSampler; |
| |
| /** |
| * Creates 2D plot of sampling output. |
| * It is a "manual" check that could help ensure that no artefacts |
| * exist in some tiny region of the expected range, due to loss of |
| * accuracy, e.g. when porting C code based on 32-bits "float" to |
| * "Commons RNG" that uses Java "double" (64-bits). |
| */ |
| public class UniformSamplingVisualCheck { |
| /** RNG. */ |
| private final UniformRandomProvider rng = RandomSource.create(RandomSource.XOR_SHIFT_1024_S); |
| /** Samplers. */ |
| private final ContinuousSampler[] samplers = new ContinuousSampler[] { |
| new ZigguratNormalizedGaussianSampler(rng), |
| new MarsagliaNormalizedGaussianSampler(rng), |
| new BoxMullerNormalizedGaussianSampler(rng), |
| }; |
| |
| /** |
| * Program entry point. |
| * |
| * @param args Unused. |
| */ |
| public static void main(String[] args) { |
| final float lo = 0.1f; |
| final int bands = 2; |
| float hi = lo; |
| for (int i = 0; i < bands; i++) { |
| hi = Math.nextUp(hi); |
| } |
| System.out.printf("# lo=%.10e hi=%.10e", lo, hi); |
| System.out.println(); |
| |
| final UniformSamplingVisualCheck app = new UniformSamplingVisualCheck(); |
| |
| while (true) { |
| System.out.printf("%.16e\t", app.rng.nextDouble()); |
| |
| for (ContinuousSampler s : app.samplers) { |
| while (true) { |
| final double r = s.sample(); |
| if (r < lo || |
| r > hi) { |
| // Discard numbers outside the tiny region. |
| continue; |
| } |
| |
| System.out.printf("%.16e ", r); |
| break; |
| } |
| } |
| |
| System.out.println(); |
| } |
| } |
| } |