VB Random Number Example

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Imports System

Imports CenterSpace.NMath.Core

Namespace CenterSpace.NMath.Core.Examples.VisualBasic

  ' A .NET example in Visual Basic showing how to generate random number from a normal distribution,
  ' using the class RandGenNormal, and place them in a histogram.
  Module NormalRNGExample

    Sub Main()

      Console.WriteLine()

      Dim Mean As Double = 70.0
      Dim Variance As Double = 10.0

      ' Create a default generator. The default generator will generate 
      ' random numbers from a normal distribution with a specified mean
      ' and variance.
      Dim NormalRng As New RandGenNormal(Mean, Variance)

      ' Now construct a vector of random numbers using this generator.
      Dim NumRandDeviates As Integer = 200
      Dim RandomVec As New DoubleVector(NumRandDeviates, NormalRng)

      ' Create a histogram with equal sized bins for the random numbers.
      Dim NumBins As Integer = 20
      Dim H As New Histogram(NumBins, RandomVec)

      Console.WriteLine()

      ' Print out the histogram in a "stem leaf" format.
      Console.Write(NumRandDeviates.ToString() + " random deviates from a normal(")
      Console.Write(Mean.ToString() + "," + Variance.ToString())
      Console.WriteLine(") distribution:")
      Console.WriteLine(H.StemLeaf())

      ' Change the mean and variance for generator and check the mean and  
      ' variance of the generated deviates.
      NormalRng.Mean = -2.0
      NormalRng.Variance = 1.0
      RandomVec = New DoubleVector(1000, NormalRng)

      Dim MeanOfDeviates As Double = NMathFunctions.Mean(RandomVec)
      Console.Write("Distribution mean = " + NormalRng.Mean.ToString() + ",")
      Console.WriteLine("mean of deviates = " + MeanOfDeviates.ToString())

      Dim VarianceOfDeviates As Double = NMathFunctions.Variance(RandomVec)
      Console.Write("Distribution variance = " + NormalRng.Variance.ToString())
      Console.WriteLine(", variance of deviates = " + VarianceOfDeviates.ToString())

      ' Replace the vector's contents with new random numbers
      RandomVec.Transform(New Func(Of Double)(AddressOf NormalRng.NextDouble))

      Console.WriteLine()
      Console.WriteLine("Press Enter Key")
      Console.Read()

    End Sub
  End Module
End Namespace

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