How update value in static text in GUI while running function e.g. pdepe

I am using the pdepe tool in a GUI

If the RUN-Button in the GUI is pressed a function is running the pdepe. It looks something like this:

% --- Executes on button press in runbutton.

function runbutton_Callback(hObject, eventdata, handles)

% hObject    handle to runbutton (see GCBO)

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

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

...

[xmesh, result]= pdepe_program(input1, input2);

...

guidata(hObject,handles);

The pdepe_program is solving the problem for different time iterations i. Due to the fact that the simulation time is long, I would like to show the current iteration as a static text (or edit text) in the GUI while the pdepe tool is solving (live update). The problem is that the handle of the static text is not available in the pdepe_program. So how can I get the value of i out of the function and show it in the GUI?