functions in testgl.i -

             sho_drum  
 
     Display a drum head moving in 3D.  
     The drumhead is initially stationary, but has a bump near one  
     edge.  Yorick is solving a 2D wave equation to compute the  
     evolution of this bump.  
     There is an optional argument to sho_drum: the   
     time limit on the duration of the movie in seconds (default  
     is 60 seconds).  
       
     The size of the grid is set by the external variable drum_size.