GUIDE: userdata and popupmenu

Hi, I'm new to GUI's and am starting to learn about GUIDE. I've got a problem that I have to solve, and can't get it to work the way I want.

I'm using edit fields, and want a button to calculate stuff using the input. I can get it to work using separate edit fields for all values I want, that's not the problem. I can use for example one of these "Radius1 = str2double(get(handles.edit1,'String'));" for every value.

However, I want to use a popup menu to select a blood vessel (number 1, 2 or 3) and use 2 edit boxes to enter the radius and length of that vessel. Each edit box has to be used 3 times (once for each vessel). All values have to be saved in userdata to be used on a button press.

I don't need you to solve my specific problem, but it would be very helpful if someone could show me an example of a GUI created by GUIDE that uses one edit field for multiple values using a popup menu, and displays a result on the screen. For example: a GUI with popup menu choices A and B, one input field, saving data to userdata, and calculating and displaying C (A + B or something) in a text box. That should give me the opportunity to study a working example and solve my own problem.