' FB 1.05.0 Win64

Type FuncType As Function(As Double) As Double

' These 'shared' variables are available to all functions defined below
Dim Shared p As UInteger
Dim Shared list() As Double

Function sma(n As Double) As Double
  Redim Preserve list(0 To UBound(list) + 1)
  list(UBound(list)) = n
  Dim start As Integer = 0
  Dim length As Integer = UBound(list) + 1
  If length > p Then
    start = UBound(list) - p + 1
    length = p
  End If
  Dim sum As Double = 0.0
  For i As Integer = start To UBound(list)
    sum += list(i)
  Next
  Return sum / length
End Function

Function initSma(period As Uinteger) As FuncType
  p = period
  Erase list '' ensure the array is empty on each initialization
  Return @sma
End Function

Dim As FuncType ma = initSma(3)
Print "Period = "; p
Print
For i As Integer = 0 To 9
  Print "Add"; i; " => moving average ="; ma(i)
Next
Print
ma = initSma(5)
Print "Period = "; p
Print
For i As Integer = 9 To 0 Step -1
  Print "Add"; i; " => moving average ="; ma(i)
Next
Print
Print "Press any key to quit"
Sleep