Chapter 8 Vibration Toolbox NotesThe three main files of the chapter 8 toolbox are named VTB_?.m.  Together they form a simple finite element code which includes a graphical preprocessor for entering the model (VTB8_1),  the main body of the finite element code for solving the problem (VTB8_2), and a graphical post processor for viewing the problem solution (VTB8_3).  Other files exist as examples and are described in the 'EXAMPLES' section.THE GRAPHIC PREPROCESSOR (VTB8_1):   The graphic preprocessor is a very simple preprocessor which allows simple problems to be defined graphically.  Note that editing of previously entered data is not possible with the graphic preprocessor.  For more complicated models, it is suggested that the user create a script file which defines the model and use the main body of the finite element code directly.  In machines without a graphic (window) user interface (GUI) the view will move between the graphic screen and the command screen.  Pressing return in the graphics screen will bring the view back to the command screen unless you are picking a node with a pointing device such as a mouse or trackball.  Make sure that you know the node number(s) you want to select before returning to the command window.  On GUI systems, it should be possible to position the command and graphics windows next to each other such that both can be seen at the same time.  When selecting nodes, it is possible to enter either the node number or use a mouse (or other pointing device).  When a node is selected it is represented by an 寈