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 */
017package org.apache.commons.math3.distribution;
018
019import org.apache.commons.math3.exception.NotStrictlyPositiveException;
020import org.apache.commons.math3.exception.util.LocalizedFormats;
021import 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 */
029public 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}