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/// ------------------------------------------------------
/// RandomOps - (Pseudo) Random Number Generator For C#
/// Copyright (C) 2003-2010 Magnus Erik Hvass Pedersen.
/// Please see the file license.txt for license details.
/// RandomOps on the internet: http://www.Hvass-Labs.org/
/// ------------------------------------------------------
namespace RandomOps
{
/// <summary>
/// Base-class for an RNG.
/// </summary>
/// <remarks>
/// You must at least implement the Uniform() method, which is
/// used by default by all the other methods that can be overrided
/// to provide more efficient implementations for your particular RNG.
/// </remarks>
public abstract partial class Random
{
/// <summary>
/// Name of the RNG.
/// </summary>
public abstract string Name
{
get;
}
/// <summary>
/// Draw a uniform random number in the exclusive range (0,1).
/// </summary>
/// <remarks>
/// This must be implemented in every inherited class. It is important
/// that it does not return the end-point values of zero or one, or
/// else some of the methods which use Uniform() to generate their
/// random numbers will not work.
/// </remarks>
public abstract double Uniform();
/// <summary>
/// Draw a uniform random number in the exclusive range (low,high).
/// Thread-safe if Uniform() is thread-safe.
/// </summary>
/// <param name="low">The lowest value in the range.</param>
/// <param name="high">The highest value in the range.</param>
public virtual double Uniform(double low, double high)
{
// Re-use the paremeter-less Uniform() method.
return Uniform() * (high - low) + low;
}
/// <summary>
/// Draw a random boolean with equal probability of true or false.
/// Thread-safe if Uniform() is thread-safe.
/// </summary>
public virtual bool Bool()
{
// Re-use the Uniform() method.
return Uniform() < 0.5;
}
/// <summary>
/// Draw a random boolean with probability p of true and (1-p) of false.
/// Thread-safe if Uniform() is thread-safe.
/// </summary>
public virtual bool Bool(double p)
{
// Re-use the Uniform() method.
return Uniform() < p;
}
/// <summary>
/// Draw a random and uniform byte.
/// Thread-safe if Index() is thread-safe.
/// </summary>
/// <remarks>
/// The default implementation uses Index() which in turn uses
/// Uniform(). This is quite expensive for generating just
/// one byte, but is the most generally viable way of doing it
/// for many PRNGs, because their low-order bits are not very
/// random. Some PRNGs may offer much better ways of generating
/// just a single random byte, in which case this method should
/// of course be overrided.
/// </remarks>
public virtual byte Byte()
{
// Re-use the Index() method.
return (byte)Index((int)System.Byte.MaxValue + 1);
}
/// <summary>
/// Draw an array of random and uniform bytes.
/// Thread-safe if Byte() is thread-safe.
/// </summary>
/// <param name="length">The array length requested.</param>
public virtual byte[] Bytes(int length)
{
// Re-use the Byte() method.
byte[] arr = new byte[length];
for (int i = 0; i < length; i++)
{
arr[i] = Byte();
}
return arr;
}
}
}
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