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.random;
018
019
020/**
021 * Interface extracted from <code>java.util.Random</code>.  This interface is
022 * implemented by {@link AbstractRandomGenerator}.
023 *
024 * @since 1.1
025 * @version $Id: RandomGenerator.java 1416643 2012-12-03 19:37:14Z tn $
026 */
027public interface RandomGenerator {
028
029    /**
030     * Sets the seed of the underlying random number generator using an
031     * <code>int</code> seed.
032     * <p>Sequences of values generated starting with the same seeds
033     * should be identical.
034     * </p>
035     * @param seed the seed value
036     */
037    void setSeed(int seed);
038
039    /**
040     * Sets the seed of the underlying random number generator using an
041     * <code>int</code> array seed.
042     * <p>Sequences of values generated starting with the same seeds
043     * should be identical.
044     * </p>
045     * @param seed the seed value
046     */
047    void setSeed(int[] seed);
048
049    /**
050     * Sets the seed of the underlying random number generator using a
051     * <code>long</code> seed.
052     * <p>Sequences of values generated starting with the same seeds
053     * should be identical.
054     * </p>
055     * @param seed the seed value
056     */
057    void setSeed(long seed);
058
059    /**
060     * Generates random bytes and places them into a user-supplied
061     * byte array.  The number of random bytes produced is equal to
062     * the length of the byte array.
063     *
064     * @param bytes the non-null byte array in which to put the
065     * random bytes
066     */
067    void nextBytes(byte[] bytes);
068
069    /**
070     * Returns the next pseudorandom, uniformly distributed <code>int</code>
071     * value from this random number generator's sequence.
072     * All 2<font size="-1"><sup>32</sup></font> possible <tt>int</tt> values
073     * should be produced with  (approximately) equal probability.
074     *
075     * @return the next pseudorandom, uniformly distributed <code>int</code>
076     *  value from this random number generator's sequence
077     */
078    int nextInt();
079
080    /**
081     * Returns a pseudorandom, uniformly distributed <tt>int</tt> value
082     * between 0 (inclusive) and the specified value (exclusive), drawn from
083     * this random number generator's sequence.
084     *
085     * @param n the bound on the random number to be returned.  Must be
086     * positive.
087     * @return  a pseudorandom, uniformly distributed <tt>int</tt>
088     * value between 0 (inclusive) and n (exclusive).
089     * @throws IllegalArgumentException  if n is not positive.
090     */
091    int nextInt(int n);
092
093    /**
094     * Returns the next pseudorandom, uniformly distributed <code>long</code>
095     * value from this random number generator's sequence.  All
096     * 2<font size="-1"><sup>64</sup></font> possible <tt>long</tt> values
097     * should be produced with (approximately) equal probability.
098     *
099     * @return  the next pseudorandom, uniformly distributed <code>long</code>
100     *value from this random number generator's sequence
101     */
102    long nextLong();
103
104    /**
105     * Returns the next pseudorandom, uniformly distributed
106     * <code>boolean</code> value from this random number generator's
107     * sequence.
108     *
109     * @return  the next pseudorandom, uniformly distributed
110     * <code>boolean</code> value from this random number generator's
111     * sequence
112     */
113    boolean nextBoolean();
114
115    /**
116     * Returns the next pseudorandom, uniformly distributed <code>float</code>
117     * value between <code>0.0</code> and <code>1.0</code> from this random
118     * number generator's sequence.
119     *
120     * @return  the next pseudorandom, uniformly distributed <code>float</code>
121     * value between <code>0.0</code> and <code>1.0</code> from this
122     * random number generator's sequence
123     */
124    float nextFloat();
125
126    /**
127     * Returns the next pseudorandom, uniformly distributed
128     * <code>double</code> value between <code>0.0</code> and
129     * <code>1.0</code> from this random number generator's sequence.
130     *
131     * @return  the next pseudorandom, uniformly distributed
132     *  <code>double</code> value between <code>0.0</code> and
133     *  <code>1.0</code> from this random number generator's sequence
134     */
135    double nextDouble();
136
137    /**
138     * Returns the next pseudorandom, Gaussian ("normally") distributed
139     * <code>double</code> value with mean <code>0.0</code> and standard
140     * deviation <code>1.0</code> from this random number generator's sequence.
141     *
142     * @return  the next pseudorandom, Gaussian ("normally") distributed
143     * <code>double</code> value with mean <code>0.0</code> and
144     * standard deviation <code>1.0</code> from this random number
145     *  generator's sequence
146     */
147    double nextGaussian();
148}