Button group alter values

Hi, so i have a popup menu that has the data stored within it as different cases. However i also have a button group which i want to use to change the units of the data and replot it. The first section is all fine, it plots the graph as i want it, the code can be seen below.

function choose_Callback(hObject, eventdata, handles)
% hObject    handle to choose (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.choose,'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;
  end
   S.P=10.^(S.A-(S.B./(S.C+S.T)));
   plot(S.T,S.P)
     set(handles.choose, 'UserData', S);

The problem arrises when i try to use the button group;

function pressureset_SelectionChangedFcn(hObject, eventdata, handles)

% hObject    handle to the selected object in pressureset 
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    structure with handles and user data (see GUIDATA)
sel_obj = get(handles.pressureset, 'selectedobject');
avial_object = get(handles.pressureset,'children');
if sel_obj==avial_object(1)
    set(handles.choose,'value')
 elseif sel_obj==avial_object(2)
    set(handles.choose,'value', S.P.*(101.325/760))

I get the error undefined variable S.T, any idea how i can bring over the data from the first section? Many Thanks.

Answer 1

[Rajesh Dubal]

The error occurs because the scope of the variable S is locally restricted to the function choose_Callback. What I personally do is save these in the handles structure.

Here is what you can do :

function choose_Callback(hObject, eventdata, handles)

% hObject    handle to choose (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.choose,'Value')
    case 1
      handles.S.A=8.021;
      handles.S.B=1936.01;
      handles.S.C=258.451;
      handles.S.Tmin=18;
      handles.S.Tmax=118;
      handles.S.T=S.Tmin:((S.Tmax-S.Tmin)/100):S.Tmax;
    case 2
      handles.S.A=8.021;
      handles.S.B=1936.01;
      handles.S.C=258.451;
      handles.S.Tmin=18;
      handles.S.Tmax=118;
      handles.S.T=S.Tmin:((S.Tmax-S.Tmin)/100):S.Tmax;
    case 3
      handles.S.A=7.11714;
      handles.S.B=1210.595;
      handles.S.C=229.664;
      handles.S.Tmin=-13;
      handles.S.Tmax=55;
      handles.S.T=S.Tmin:((S.Tmax-S.Tmin)/100):S.Tmax;
  end
   handles.S.P=10.^(handles.S.A-(handles.S.B./(handles.S.C+handles.S.T)));
   plot(handles.S.T,handles.S.P)
     set(handles.choose, 'UserData', handles.S);
  guidata(hObject, handles); %to update the handles structure

And the button callback

function pressureset_SelectionChangedFcn(hObject, eventdata, handles)
% hObject    handle to the selected object in pressureset 
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    structure with handles and user data (see GUIDATA)
sel_obj = get(handles.pressureset, 'selectedobject');
avial_object = get(handles.pressureset,'children');
if sel_obj==avial_object(1)
    set(handles.choose,'value')
 elseif sel_obj==avial_object(2)
    set(handles.choose,'value', handles.S.P.*(101.325/760))
 guidata(hObject, handles); %to update the handles structure

[H.Hogarth]

Hi, thanks for the quick response, when i select the second button in the button group i no longer get an error but the axis dont update to the new S.P value. Any ideas? Thanks

[Rajesh Dubal]

You need to plot the curve again in the pressureset button callback, because you are not updating the plot anywhere in that callback.