From: Walter Roberson on
Rick T wrote:

> function slider1_Callback(hObject, eventdata, handles)
>
> sliderValue = get(handles.slider1,'Value');
> %puts the slider value into the edit text component
> set(handles.sliderValue_editText,'String', num2str(sliderValue));
>
> freq=1;

That line creates a variable named 'freq', not a variable named 'handles.freq'.

> set(handles.freq,'Value',sliderValue); %sets freq when slider changes
> %-------error it refers too above
>
> % Update handles structure
> guidata(hObject, handles);