public partial class Bewegungsdesign_View : Window
{
    public Bewegungsdesign_View()
    {
        InitializeComponent();
    }

    private void Button_Click(object sender, RoutedEventArgs e)
    {
        Norm_Gerade G = new();

        //Using Math.Sin(x) --> no performance issues at all
        //var func1 = new Func<double, double?>((x) => Math.Sin(x));
        Func<double, double?> func1 = new((x) => G.Normalised_Function_F(x));

        Plot_Test.Plot.AddFunction(func1);
        Plot_Test.Refresh();
    }

    private class Norm_Gerade
    {
        public double? Normalised_Function_F(double z)
        {
            return 0 <= z && z <= 1 ? z : null;
        }
    }
}