Function Xgcd(a, b)
Dim result(3)
    x = 0: y = 1: result(1) = 1: result(2) = 0: result(3) = a
    Do While b > 0
        temp = b
        quotient = Int(result(3) / b)
        b = result(3) Mod b
        result(3) = temp
        temp = x
        x = result(1) - quotient * x
        result(1) = temp
        temp = y
        y = result(2) - quotient * y
        result(2) = temp
    Loop
    Xgcd = result
End Function


'Example
Sub getXgcd()
Dim xg()
    xg() = Xgcd(838041641, 198491329)
    Debug.Print "ax + by = gcd(838041641, 198491329)" & Chr(13) & "x is " & xg(1) & ", y is " & xg(2) & " and a is " & xg(3)
End Sub