Func _ATAN2(Const $NY, Const $NX)
    Const $NPI = 3.14159265358979
    Local $NRESULT
    If IsNumber($NY) = 0 Then
        SetError(1)
        Return 0
    ElseIf IsNumber($NX) = 0 Then
        SetError(1)
        Return 0
    EndIf
    If $NX = 0 Then
        If $NY > 0 Then
            $NRESULT = $NPI / 2
        ElseIf $NY < 0 Then
            $NRESULT = 3 * $NPI / 2
        Else
            SetError(2)
            Return 0
        EndIf
    ElseIf $NX < 0 Then
        $NRESULT = ATan($NY / $NX) + $NPI
    Else
        $NRESULT = ATan($NY / $NX)
    EndIf
    While $NRESULT < 0
        $NRESULT += 2 * $NPI
    WEnd
    Return $NRESULT
EndFunc