forked from tsai/mathnet-numerics
Jurgen Van Gael
17 years ago
5 changed files with 213 additions and 8 deletions
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// <copyright file="AbstractRandomNumberGenerator.cs" company="Math.NET">
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// Math.NET Numerics, part of the Math.NET Project
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// http://mathnet.opensourcedotnet.info
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//
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// Copyright (c) 2009 Math.NET
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//
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// Permission is hereby granted, free of charge, to any person
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// obtaining a copy of this software and associated documentation
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// files (the "Software"), to deal in the Software without
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// restriction, including without limitation the rights to use,
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// copy, modify, merge, publish, distribute, sublicense, and/or sell
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// copies of the Software, and to permit persons to whom the
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// Software is furnished to do so, subject to the following
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// conditions:
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//
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// The above copyright notice and this permission notice shall be
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// included in all copies or substantial portions of the Software.
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//
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// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
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// EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
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// OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
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// NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
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// HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
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// WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
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// FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
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// OTHER DEALINGS IN THE SOFTWARE.
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// </copyright>
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namespace MathNet.Numerics.Random |
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{ |
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using System; |
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using System.Collections.Generic; |
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using Properties; |
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/// <summary>
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/// Abstract class for random number generators. This class introduces a layer between <see cref="System.Random"/>
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/// and the Math.Net Numerics random number generators to provide thread safety.
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/// </summary>
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public abstract class AbstractRandomNumberGenerator : System.Random |
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{ |
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/// <summary>
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/// A delegate type that represents a method that generates random numbers.
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/// </summary>
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/// <returns>Randomly distributed numbers.</returns>
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private delegate double SampleMethod(); |
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/// <summary>
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/// The method that actually generates samples.
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/// </summary>
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private readonly SampleMethod _sampleMethod; |
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/// <summary>
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/// The object that will be locked for thread safety.
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/// </summary>
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private readonly object _lock = new object(); |
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/// <summary>
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/// Initializes a new instance of the <see cref="AbstractRandomNumberGenerator"/> class using
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/// the value of <see cref="Control.ThreadSafeRandomNumberGenerators"/> to set whether
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/// the instance is thread safe or not.
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/// </summary>
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protected AbstractRandomNumberGenerator(): this(Control.ThreadSafeRandomNumberGenerators) |
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{ |
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} |
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/// <summary>
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/// Initializes a new instance of the <see cref="AbstractRandomNumberGenerator"/> class.
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/// </summary>
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/// <param name="threadSafe">if set to <c>true</c> , the class is thread safe.</param>
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/// <remarks>Thread safe instances are two and half times slower than non-thread
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/// safe classes.</remarks>
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protected AbstractRandomNumberGenerator(bool threadSafe) |
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{ |
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_sampleMethod = threadSafe ? (SampleMethod) ThreadSafeSample : DoSample; |
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} |
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/// <summary>
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/// Returns an array of uniformly distributed random doubles in the interval [0.0,1.0].
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/// </summary>
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/// <param name="n">The size of the array.</param>
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/// <returns>
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/// An array of uniformly distributed random doubles in the interval [0.0,1.0].
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/// </returns>
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/// <exception cref="ArgumentException">if n is not greater than 0.</exception>
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public double[] NextDouble(int n) |
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{ |
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if (n < 1) |
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{ |
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throw new ArgumentException(Resources.ArgumentMustBePositive); |
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} |
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var ret = new double[n]; |
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for (int i = 0; i < ret.Length; i++) |
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{ |
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ret[i] = Sample(); |
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} |
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return ret; |
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} |
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/// <summary>
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/// Returns a nonnegative random number.
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/// </summary>
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/// <returns>
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/// A 32-bit signed integer greater than or equal to zero and less than <see cref="F:System.Int32.MaxValue"/>.
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/// </returns>
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public override int Next() |
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{ |
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return (int)(Sample() * int.MaxValue); |
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} |
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/// <summary>
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/// Returns a random number less then a specified maximum.
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/// </summary>
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/// <param name="maxValue">The exclusive upper bound of the random number returned.</param>
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/// <returns>A 32-bit signed integer less than <paramref name="maxValue"/>.</returns>
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/// <exception cref="T:System.ArgumentOutOfRangeException"><paramref name="maxValue"/> is negative. </exception>
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public override int Next(int maxValue) |
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{ |
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if (0 > maxValue) |
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{ |
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throw new ArgumentOutOfRangeException(Resources.ArgumentMustBePositive); |
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} |
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return (int) (Sample() % maxValue); |
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} |
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/// <summary>
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/// Returns a random number within a specified range.
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/// </summary>
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/// <param name="minValue">The inclusive lower bound of the random number returned.</param>
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/// <param name="maxValue">The exclusive upper bound of the random number returned. <paramref name="maxValue"/> must be greater than or equal to <paramref name="minValue"/>.</param>
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/// <returns>
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/// A 32-bit signed integer greater than or equal to <paramref name="minValue"/> and less than <paramref name="maxValue"/>; that is, the range of return values includes <paramref name="minValue"/> but not <paramref name="maxValue"/>. If <paramref name="minValue"/> equals <paramref name="maxValue"/>, <paramref name="minValue"/> is returned.
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/// </returns>
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/// <exception cref="T:System.ArgumentOutOfRangeException"><paramref name="minValue"/> is greater than <paramref name="maxValue"/>. </exception>
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public override int Next(int minValue, int maxValue) |
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{ |
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if (minValue > maxValue) |
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{ |
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throw new ArgumentOutOfRangeException(Resources.ArgumentMinValueGreaterThanMaxValue); |
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} |
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return (int) (Sample()*(maxValue - minValue)) + minValue; |
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} |
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/// <summary>
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/// Fills the elements of a specified array of bytes with random numbers.
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/// </summary>
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/// <param name="buffer">An array of bytes to contain random numbers.</param>
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/// <exception cref="T:System.ArgumentNullException"><paramref name="buffer"/> is null. </exception>
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public override void NextBytes(byte[] buffer) |
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{ |
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if (buffer == null) |
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{ |
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throw new ArgumentNullException("buffer"); |
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} |
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for (int i = 0; i < buffer.Length; i++) |
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{ |
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buffer[i] = (byte) (Next()%256); |
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} |
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} |
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/// <summary>
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/// Returns a random number between 0.0 and 1.0.
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/// </summary>
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/// <returns>A double-precision floating point number greater than or equal to 0.0, and less than 1.0.</returns>
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protected override double Sample() |
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{ |
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return _sampleMethod(); |
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} |
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/// <summary>
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/// Thread safe version of <seealso cref="DoSample"/> which returns a random number between 0.0 and 1.0.
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/// </summary>
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/// <returns></returns>
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private double ThreadSafeSample() |
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{ |
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lock(_lock) |
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{ |
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return DoSample(); |
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} |
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} |
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/// <summary>
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/// Returns a random number between 0.0 and 1.0.
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/// </summary>
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/// <returns>
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/// A double-precision floating point number greater than or equal to 0.0, and less than 1.0.
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/// </returns>
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protected abstract double DoSample(); |
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} |
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} |
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