'Simulate a Poisson distributed randome variable with parameter lambda

Public Function Randpoisson(ByVal lambda As Double) As Double
       Dim N As Integer
       Dim temp As Double

       temp = alea()
       N = 1
       While (temp > Exp(-lambda))
             N = N + 1
             temp = temp * alea()
       Wend

       Randpoisson = N - 1
End Function