Random Number Generators in Visual Basic QuickStart Sample

Illustrates how to use specialized random number generator classes in the Numerics.NET.Statistics.Random namespace in Visual Basic.

This sample is also available in: C#, F#, IronPython.

Overview

This QuickStart sample demonstrates how to use the various random number generator classes available in Numerics.NET. These classes provide alternatives to the standard System.Random class with additional features and different algorithms.

The sample covers three main random number generator types:

• The ExtendedRandom class which enhances System.Random with additional functionality like filling arrays
• The RANLUX generators which offer different “luxury levels” of random number quality
• The Generalized Feedback Shift Register (GFSR) generator
• The Mersenne Twister, a variant of GFSR that is widely used in scientific computing

For each generator type, the sample shows how to:

• Create instances with different constructors and parameters
• Generate random integers and floating point numbers
• Fill arrays with random values
• Select appropriate luxury levels for RANLUX generators

The sample also mentions that all generators can produce random variates from arbitrary probability distributions, with a reference to the NonUniformRandomNumbers sample for details.

The code

Imports Numerics.NET
Imports Numerics.NET.Random

    ' Illustrates the use of the classes that implement
    ' pseudo-random number generators.
    Module RandomNumberGenerators

        Sub Main()
        ' The license is verified at runtime. We're using
        ' a 30 day trial key here. For more information, see
        '     https://numerics.net/trial-key
        Numerics.NET.License.Verify("your-trial-key-here")

        ' This QuickStart Sample gives an overview of the pseudo-random
        ' number generators that provide an alternative for the
        ' System.Random class..

        '
        ' ExtendedRandom class
        '

        ' The ExtendedRandom class simply extends the functionality
        ' of the System.Random class:
        Dim extended As ExtendedRandom = New ExtendedRandom
        Dim intValues As Integer() = New Integer(100) {}
        Dim doubleValues As Double() = New Double(100) {}

        ' The fill method fills an array of integers with random numbers
        extended.Fill(intValues)
        Console.WriteLine($"integer(99) = {intValues(99)}")

        ' Or, it can generate uniform real values:
        extended.Fill(doubleValues)
        Console.WriteLine($"double(99) = {doubleValues(99)}")

        ' All random number generators can also produce variates
        ' from any user-specified probability distribution.
        ' The NonUniformRandomNumbers sample illustrates
        ' how to do this.

        '
        ' RANLUX Generators
        '

        ' The RANLUX generators are available with three different
        ' 'luxury levels.' Each level produces random numbers of
        ' increasing quality at a performance cost.
        '
        ' There are four constructors. The first constructor uses the
        ' default seed and the default (lowest) luxury level:
        Dim ranLux1 As RanLux = New RanLux

        ' We can specify a seed value as well:
        Dim ranLux2 As RanLux = New RanLux(99)

        ' We can specify the luxury level in the constructor:
        Dim ranLux3 As RanLux = New RanLux(RanLuxLuxuryLevel.Better)

        ' Finally, we can specify both a seed and the luxury level:
        Dim ranLux4 As RanLux = New RanLux(99, RanLuxLuxuryLevel.Best)

        ' All methods of System.Random and ExtendedRandom are available:
        ranLux1.Fill(intValues)
        ranLux2.Fill(doubleValues)
        Console.WriteLine($"Integer from RanLux(Best): {ranLux3.Next(100)}")

        '
        ' Generalized Feedback Shift Register Generator
        '

        ' This generator is implemented by the GfsrGenerator class.
        ' It has three constructors. A default constructor that uses
        ' a default seed value:
        Dim gfsr1 As GfsrGenerator = New GfsrGenerator

        ' A constructor that takes a single integer seed:
        Dim gfsr2 As GfsrGenerator = New GfsrGenerator(99)

        ' And a constructor that takes an array of integers
        ' as its seed. The maximum size of this seed array
        ' is 2^14-1 = 16383.
        Dim gfsr3 As GfsrGenerator = New GfsrGenerator(New Integer() {99, 17, Integer.MaxValue})

        ' Once again, all standard methods are available.
        Console.WriteLine($"Double from GFSR: {gfsr2.NextDouble()}")

        '
        ' Mersenne Twister
        '

        ' The Mersenne Twister is a variation on the GFSR generator and,
        ' not surprisingly, also has three constructors:
        Dim mersenne1 As MersenneTwister = New MersenneTwister
        Dim mersenne2 As MersenneTwister = New MersenneTwister(99)
        Dim mersenne3 As MersenneTwister = New MersenneTwister(New Integer() {99, 17, Integer.MaxValue})

        Console.Write("Press any key to exit.")
        Console.ReadLine()

    End Sub

End Module