In GUIDE, How can I perform differentiation of a function input by the user?

The following is how I get the function input by the user. I would like to add a push button on the GUIDE that can differentiate this function, and another push button to plot the differentiated function.

Thank you!

function y1_Callback(hObject, eventdata, handles) % hObject handle to y1 (see GCBO) % eventdata reserved - to be defined in a future version of MATLAB % handles structure with handles and user data (see GUIDATA)

% Hints: get(hObject,'String') returns contents of y1 as text % str2double(get(hObject,'String')) returns contents of y1 as a double stringf=get(hObject,'String'); handles.stringf=stringf; guidata(hObject,handles); y1=@(x) eval(get(hObject,'String')); handles.y1=y1; guidata(hObject,handles);