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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    *      https://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  
18  /*
19   * This is not the original file distributed by the Apache Software Foundation
20   * It has been modified by the Hipparchus project
21   */
22  package org.hipparchus.distribution.multivariate;
23  
24  import org.hipparchus.distribution.MultivariateRealDistribution;
25  import org.hipparchus.exception.LocalizedCoreFormats;
26  import org.hipparchus.exception.MathIllegalArgumentException;
27  import org.hipparchus.random.RandomGenerator;
28  
29  /**
30   * Base class for multivariate probability distributions.
31   */
32  public abstract class AbstractMultivariateRealDistribution
33      implements MultivariateRealDistribution {
34      /** RNG instance used to generate samples from the distribution. */
35      protected final RandomGenerator random;
36      /** The number of dimensions or columns in the multivariate distribution. */
37      private final int dimension;
38  
39      /** Simple constructor.
40       * @param rng Random number generator.
41       * @param n Number of dimensions.
42       */
43      protected AbstractMultivariateRealDistribution(RandomGenerator rng,
44                                                     int n) {
45          random = rng;
46          dimension = n;
47      }
48  
49      /** {@inheritDoc} */
50      @Override
51      public void reseedRandomGenerator(long seed) {
52          random.setSeed(seed);
53      }
54  
55      /** {@inheritDoc} */
56      @Override
57      public int getDimension() {
58          return dimension;
59      }
60  
61      /** {@inheritDoc} */
62      @Override
63      public abstract double[] sample();
64  
65      /** {@inheritDoc} */
66      @Override
67      public double[][] sample(final int sampleSize) {
68          if (sampleSize <= 0) {
69              throw new MathIllegalArgumentException(LocalizedCoreFormats.NUMBER_OF_SAMPLES,
70                                                     sampleSize);
71          }
72          final double[][] out = new double[sampleSize][dimension];
73          for (int i = 0; i < sampleSize; i++) {
74              out[i] = sample();
75          }
76          return out;
77      }
78  }