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