So you want to have a drop-down selection menu, from which you can select the function or functions you want to operate on. If you already have a GUI, you can just put in two uicontrols with the 'popupmenu' 'Style'. As a 'String', you give it a cell array with the function names. Then you make a button that will see which functions were selected by the user (check the 'Value' property of the popupmenus), and will do the computation.

If you don't want a GUI for anything but selecting these, then you could just use a dialog box. The built-in "listdlg" might do it for you if you check user input. Otherwise, you probably want to make your own modal "dialog", and add the uicontrols in it the way I mentioned before.

No, you should NEVER throw away the setup discs that came with your computer! (Hey! That's the best I can do! If you want a better answer, either post this in the forum of your language, or re-post here using English!)