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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  public class ContinuousUniformSampler
25      extends SamplerBase
26      implements ContinuousSampler {
27      /** Lower bound. */
28      private final double lo;
29      /** Higher bound. */
30      private final double hi;
31      /** Underlying source of randomness. */
32      private final UniformRandomProvider rng;
33  
34      /**
35       * @param rng Generator of uniformly distributed random numbers.
36       * @param lo Lower bound.
37       * @param hi Higher bound.
38       */
39      public ContinuousUniformSampler(UniformRandomProvider rng,
40                                      double lo,
41                                      double hi) {
42          super(null);
43          this.rng = rng;
44          this.lo = lo;
45          this.hi = hi;
46      }
47  
48      /** {@inheritDoc} */
49      @Override
50      public double sample() {
51          final double u = rng.nextDouble();
52          return u * hi + (1 - u) * lo;
53      }
54  
55      /** {@inheritDoc} */
56      @Override
57      public String toString() {
58          return "Uniform deviate [" + rng.toString() + "]";
59      }
60  }