Local $iRandom = Random(1, 1000)
MsgBox(64, "_SquareRoot()", "Quadratwurzel aus " & $iRandom & " ist " & _SquareRoot($iRandom))

Func _SquareRoot($fValue, $iDelta = 1e-15)
    Local $a = 1, $b = $fValue, $c

    If $fValue < 0 Then Return 0

    While Abs($a-$b) > $iDelta And $b <> $c
        $c = $b
        $a = ($a + $b) / 2
        $b = $fValue / $a
    WEnd

    Return $a
EndFunc