Module NullstellenFinden

    Function f(ByVal x As Double) As Double
        Return Math.Sin(x)
    End Function


    Sub Main()

        Dim a, b, m, ya, yb, ym As Double
        Dim str As String
        Dim n As Integer = 0

        Console.WriteLine("a:")
        str = Console.ReadLine()
        a = Double.Parse(str)
        Console.WriteLine("b:")
        str = Console.ReadLine()
        b = Double.Parse(str)

        Console.WriteLine("Eingabe war: " + Format(a) + " und " + Format(b))

        Do
            m = (a + b) / 2

            ya = f(a)
            ym = f(m)
            yb = f(b)

            n = n + 1

            If ya * yb > 0 Then
                Console.WriteLine("Keine Nullstelle im Intervall")
                Exit Do
            Else
                If ya * ym > 0 Then
                    a = m
                Else
                    b = m
                End If
            End If

        Loop Until Math.Abs(ym) < 10.0 ^ -12

        Console.WriteLine("Nullstelle: " + Format(m) + " nach " + Format(n) + " Durchläufen")


    End Sub

End Module