popup menu callback not plotting graph

Hi, so this is only the start of my design and i wanted to test if the data stored in the dropdown menu is plotted.

However when i run the code and select a item from the dropdown menu nothing is plotted, there are no error codes or anything. Here is my code below:

function liquids_Callback(hObject, eventdata, handles)

% hObject    handle to liquids (see GCBO)

% eventdata  reserved - to be defined in a future version of MATLAB

% handles    structure with handles and user data (see GUIDATA)

switch get(handles.liquids,'Value') 

      case 1
      S.A=8.021;
      S.B=1936.01;
      S.C=258.451;
      S.Tmin=18;
      S.Tmax=118;
      S.T=S.Tmin:((S.Tmax-S.Tmin)/100):S.Tmax;
      case 2
      S.A=8.021;
      S.B=1936.01;
      S.C=258.451;
      S.Tmin=18;
      S.Tmax=118;
      S.T=S.Tmin:((S.Tmax-S.Tmin)/100):S.Tmax;
      case 3
      S.A=7.11714;
      S.B=1210.595;
      S.C=229.664;
      S.Tmin=-13;
      S.Tmax=55;
      S.T=S.Tmin:((S.Tmax-S.Tmin)/100):S.Tmax;
   otherwise
        P=10.^(S.A-(S.B./(S.C+S.T)))
        plot(S.T,P)
  end 
  set(handles.liquids, 'UserData', S);

The liquids_Callback section is underlined in red saying it might not be in uses, but i dont understand why it wouldnt be in use.

Many Thanks.

[Walter Roberson]

What is the Tag of the popup button?

[H.Hogarth]

liquids

Answer 1

[Walter Roberson]

You are only plotting if an entry after the third one is selected. The other entries set up values in the structure S that are written to the UserData, but the UserData is not retrieved before doing the plotting.

You should put in a breakpoint at the switch statement and see if you are even getting there, and single step to see what is happening.