/// <summary>
 /// Transform Text to Filter Coefficients b
 /// replace in Schematic and plot the graph
 /// </summary>
 /// <param name="sender">sender</param>
 /// <param name="e">Arguments</param>
 private void textbox_b_TextChanged(object sender, TextChangedEventArgs e)
 {
     float[] help = new float[] { };
     if (split_text2float(textbox_b.Text, ref help))
     {
         _b = help;
         Transferfunction _Tf = new Transferfunction(_a, _b);
         if (_Simulator != null)
             _Simulator.replace_in_Schematic_at_pos(3, _Tf);
         plot_graph();
     }
 }
        /// <summary>
        /// When the Selection Changed, it will calculate the new possible loops.
        /// Ans replace the loop in the Schematic
        /// </summary>
        /// <param name="sender">sender</param>
        /// <param name="e">Arguments</param>
        private void TabControl_Strecke_SelectionChanged(object sender, SelectionChangedEventArgs e)
        {
            TabItem lbi = ((sender as TabControl).SelectedItem as TabItem);
            if (lbi.Name == "tab_Strecke_PT1")
            {
                tab_Regler_P.IsEnabled = false;
                tab_Regler_I.IsEnabled = true;
                tab_Regler_PI.IsEnabled = false;
                tab_Regler_PID.IsEnabled = false;
                TabControl_Regler.SelectedIndex = 0;
                enable_all_optimizations();

                _Simulator.replace_in_Schematic_at_pos(1, _I);
                _Simulator.replace_in_Schematic_at_pos(3, _PT1);
            }
            else if (lbi.Name == "tab_Strecke_IT1")
            {
                tab_Regler_P.IsEnabled = true;
                tab_Regler_I.IsEnabled = false;
                tab_Regler_PI.IsEnabled = true;
                tab_Regler_PID.IsEnabled = false;
                enable_all_optimizations();
                check_optimization_for_IT1();

                if (tab_Regler_PI.IsSelected == false)
                {
                    TabControl_Regler.SelectedIndex = 1;
                    _Simulator.replace_in_Schematic_at_pos(1, _P);
                }
                _Simulator.replace_in_Schematic_at_pos(3, _IT1);
            }
            else if (lbi.Name == "tab_Strecke_PT2_wdb1")
            {
                tab_Regler_P.IsEnabled = true;
                tab_Regler_I.IsEnabled = false;
                tab_Regler_PI.IsEnabled = true;
                tab_Regler_PID.IsEnabled = false;
                enable_all_optimizations();
                check_optimization_for_PT2_wdb1();

                if (tab_Regler_PI.IsSelected == false)
                {
                    TabControl_Regler.SelectedIndex = 1;
                    _Simulator.replace_in_Schematic_at_pos(1, _P);
                }
                _Simulator.replace_in_Schematic_at_pos(3, _PT2_wdb1);
            }
            else if (lbi.Name == "tab_Strecke_PT2_wdse1")
            {
                tab_Regler_P.IsEnabled = false;
                tab_Regler_I.IsEnabled = true;
                tab_Regler_PI.IsEnabled = true;
                tab_Regler_PID.IsEnabled = false;
                enable_all_optimizations();
                check_optimization_for_PT2_wdse1();

                if (tab_Regler_PI.IsSelected == false)
                {
                    TabControl_Regler.SelectedIndex = 0;
                    _Simulator.replace_in_Schematic_at_pos(1, _I);
                }
                _Simulator.replace_in_Schematic_at_pos(3, _PT2_wdse1);
            }
            else if (lbi.Name == "tab_Strecke_Beliebig")
            {
                tab_Regler_P.IsEnabled = true;
                tab_Regler_I.IsEnabled = true;
                tab_Regler_PI.IsEnabled = true;
                tab_Regler_PID.IsEnabled = true;
                butten_auslegen_I.IsEnabled = false;
                butten_auslegen_P.IsEnabled = false;
                butten_auslegen_PI.IsEnabled = false;

                Transferfunction _Tf = new Transferfunction(_a, _b);
                _Simulator.replace_in_Schematic_at_pos(3, _Tf);
            }
            plot_graph();
        }