Random number generator in VBA using Analysis Toolpack-VBA

Question

I use the following line to generate Poisson random numbers:

Application.Run("Random", "", 1, 100, 5, , 34) 

this produces 100 random numbers with Lambda (34) in an excel sheet. I would like to save the output into a variable instead of sheet. I tried

X=Application.Run("Random", "", 1, NSim, 5, , 34)

I don't get any error but nothing is saved in "X". Could you please help me how I can save the result in a variable. Thanks

Answer 1

看起来该函数返回一个布尔值而不是一个数字数组，并且只接受一个范围作为输出作为其参数之一。

Answer 2

It looks like Random is a sub routine, unless you have access to the underlying code you can't do this directly.

What you could do (albeit rather backwards) is let the sub run, then assign the result back to a variable and remove it from the sheet:

Sub MM()
    Dim generateNumbers As Integer, results As Variant
    generateNumbers = 100 '// numbers to generate

    Application.Run("Random", "", 1, generateNumbers, 5, , 34)

    results = WorksheetFunction.Transpose(Range("A1:A" & generateNumbers))
    Range("A1:A" & generateNumbers).ClearContents '// If required
End Sub

The variable results will now be an array of the results.

Answer 3

How about:

Sub MAIN()
   Dim x(1 To 100) As Variant
   Dim Lambda As Double
   Lambda = 34

   For I = 1 To 100
      x(I) = Poisson(Lambda)
   Next I

End Sub


Public Function Poisson(L As Double) As Long
   Dim I As Long, x As Double, expL As Double

   expL = Exp(-L)
   I = 0
   x = 1
   While x > expL
      I = I + 1
      x = x * Rnd()
   Wend
   Poisson = I - 1
End Function

Although it is poissonous, it's not toxic.