Fitting using pop up menu on matlab gui

i'm new in Matlab and i want to fit equations using popupmenu button on matlab gui, but i still can't work for it.

this is the code i've been working on. let's say i want to get file from an excel format file using this

% --- Executes on button press in pushbutton1.
function pushbutton1_Callback(hObject, eventdata, handles)
% hObject    handle to pushbutton1 (see GCBO)
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    structure with handles and user data (see GUIDATA)
handles.filename=uigetfile('*.xlsx');
filename=handles.filename;
set(handles.edit1,'String', filename)
data = xlsread(filename)
axes(handles.axes1)
t1 = data(:,1)
t2 = data(:,2)
plot(handles.axes1,t1,t2)
grid on

and then i use an excel file to fit equations with popup menu

popvalue = get(handles.popupmenu1, 'value')
data = xlsread(filename)
t1 = data(:,1)
t2 = data(:,2)

if (popvalue == 2)
    [xdata, ydata] = prepareCurveData(t1,t2)
    ft = fittype( 'Ms*(1-A/x-B/x^2)+(D*x)', 'independent', 'x', 'dependent', 'y' );
    opts = fitoptions( 'Method', 'NonlinearLeastSquares' );
    opts.Display = 'Off';
    [fitresult{2}, gof(2)] = fit( xData, yData, ft, opts );
    plot( handles.axes1, fitresult{2}, t1, t2 );


    
elseif (popvalue == 3)
    [xData, yData] = prepareCurveData(t1, t2 );
    ft = fittype( 'Ms*(1-A/x-B/x^2)', 'independent', 'x', 'dependent', 'y' );
    opts = fitoptions( 'Method', 'NonlinearLeastSquares' );
    opts.Display = 'Off';
    [fitresult{3}, gof(3)] = fit( xData, yData, ft, opts );
    plot( handles.axes1, fitresult{3}, xData, yData );
    

    

elseif (popvalue == 4)
    ft = fittype( 'Ms*(1-A/x-B/x^2)+(D*x)', 'independent', 'x', 'dependent', 'y' );
    opts = fitoptions( 'Method', 'NonlinearLeastSquares' );
    opts.Display = 'Off';
    
end

and this an error log i get

Unrecognized function or variable 'filename'.

Error in testskripsi>popupmenu1_Callback (line 85)
data = xlsread(filename)

Error in gui_mainfcn (line 95)
        feval(varargin{:});

Error in testskripsi (line 42)
    gui_mainfcn(gui_State, varargin{:});

Error in
matlab.graphics.internal.figfile.FigFile/read>@(hObject,eventdata)testskripsi('popupmenu1_Callback',hObject,eventdata,guidata(hObject)) 
Error while evaluating UIControl Callback.

Answer 1

[VBBV]

%if
file=uigetfile('*.xlsx')
set(handles.edit1,'String', file)
data = xlsread(file)

Try above

[VBBV]

Since youre trying to assign the filename to handles structre. The name of file need to be declared in opening function. That's why it throws error

[VBBV]

Moreover, filename is not a standard GUI component like edit box or check boxes etc. So it needs to be declared before it can be assigned to handles structure