001 /*
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements. See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License. You may obtain a copy of the License at
008 *
009 * http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017 package org.apache.commons.math3.distribution;
018
019 import org.apache.commons.math3.exception.NotStrictlyPositiveException;
020 import org.apache.commons.math3.exception.util.LocalizedFormats;
021 import org.apache.commons.math3.random.RandomGenerator;
022
023 /**
024 * Base class for multivariate probability distributions.
025 *
026 * @version $Id: AbstractMultivariateRealDistribution.java 1416643 2012-12-03 19:37:14Z tn $
027 * @since 3.1
028 */
029 public abstract class AbstractMultivariateRealDistribution
030 implements MultivariateRealDistribution {
031 /** RNG instance used to generate samples from the distribution. */
032 protected final RandomGenerator random;
033 /** The number of dimensions or columns in the multivariate distribution. */
034 private final int dimension;
035
036 /**
037 * @param rng Random number generator.
038 * @param n Number of dimensions.
039 */
040 protected AbstractMultivariateRealDistribution(RandomGenerator rng,
041 int n) {
042 random = rng;
043 dimension = n;
044 }
045
046 /** {@inheritDoc} */
047 public void reseedRandomGenerator(long seed) {
048 random.setSeed(seed);
049 }
050
051 /** {@inheritDoc} */
052 public int getDimension() {
053 return dimension;
054 }
055
056 /** {@inheritDoc} */
057 public abstract double[] sample();
058
059 /** {@inheritDoc} */
060 public double[][] sample(final int sampleSize) {
061 if (sampleSize <= 0) {
062 throw new NotStrictlyPositiveException(LocalizedFormats.NUMBER_OF_SAMPLES,
063 sampleSize);
064 }
065 final double[][] out = new double[sampleSize][dimension];
066 for (int i = 0; i < sampleSize; i++) {
067 out[i] = sample();
068 }
069 return out;
070 }
071 }