1 /* 2 * Licensed to the Apache Software Foundation (ASF) under one or more 3 * contributor license agreements. See the NOTICE file distributed with 4 * this work for additional information regarding copyright ownership. 5 * The ASF licenses this file to You under the Apache License, Version 2.0 6 * (the "License"); you may not use this file except in compliance with 7 * the License. You may obtain a copy of the License at 8 * 9 * http://www.apache.org/licenses/LICENSE-2.0 10 * 11 * Unless required by applicable law or agreed to in writing, software 12 * distributed under the License is distributed on an "AS IS" BASIS, 13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 14 * See the License for the specific language governing permissions and 15 * limitations under the License. 16 */ 17 package org.apache.commons.rng.sampling.distribution; 18 19 import org.apache.commons.rng.UniformRandomProvider; 20 21 /** 22 * Sampling from a uniform distribution. 23 * 24 * <p>Sampling uses {@link UniformRandomProvider#nextDouble()}.</p> 25 * 26 * @since 1.0 27 */ 28 public class ContinuousUniformSampler 29 extends SamplerBase 30 implements SharedStateContinuousSampler { 31 /** Lower bound. */ 32 private final double lo; 33 /** Higher bound. */ 34 private final double hi; 35 /** Underlying source of randomness. */ 36 private final UniformRandomProvider rng; 37 38 /** 39 * @param rng Generator of uniformly distributed random numbers. 40 * @param lo Lower bound. 41 * @param hi Higher bound. 42 */ 43 public ContinuousUniformSampler(UniformRandomProvider rng, 44 double lo, 45 double hi) { 46 super(null); 47 this.rng = rng; 48 this.lo = lo; 49 this.hi = hi; 50 } 51 52 /** {@inheritDoc} */ 53 @Override 54 public double sample() { 55 final double u = rng.nextDouble(); 56 return u * hi + (1 - u) * lo; 57 } 58 59 /** {@inheritDoc} */ 60 @Override 61 public String toString() { 62 return "Uniform deviate [" + rng.toString() + "]"; 63 } 64 65 /** 66 * {@inheritDoc} 67 * 68 * @since 1.3 69 */ 70 @Override 71 public SharedStateContinuousSampler withUniformRandomProvider(UniformRandomProvider rng) { 72 return new ContinuousUniformSampler(rng, lo, hi); 73 } 74 75 /** 76 * Creates a new continuous uniform distribution sampler. 77 * 78 * @param rng Generator of uniformly distributed random numbers. 79 * @param lo Lower bound. 80 * @param hi Higher bound. 81 * @return the sampler 82 * @since 1.3 83 */ 84 public static SharedStateContinuousSampler of(UniformRandomProvider rng, 85 double lo, 86 double hi) { 87 return new ContinuousUniformSampler(rng, lo, hi); 88 } 89 }