' FB 1.05.0 Win64

Function calcStandardDeviation(number As Double) As Double
  Static a() As Double
  Redim Preserve a(0 To UBound(a) + 1)
  Dim ub As UInteger = UBound(a)
  a(ub) = number
  Dim sum As Double = 0.0
  For i As UInteger = 0 To ub
    sum += a(i)
  Next
  Dim mean As Double = sum / (ub + 1)
  Dim diff As Double
  sum  = 0.0
  For i As UInteger = 0 To ub
    diff = a(i) - mean
    sum += diff * diff
  Next
  Return Sqr(sum/ (ub + 1))
End Function

Dim a(0 To 7) As Double = {2, 4, 4, 4, 5, 5, 7, 9}

For i As UInteger = 0 To 7
  Print "Added"; a(i); " SD now : "; calcStandardDeviation(a(i))
Next

Print
Print "Press any key to quit"
Sleep