 Usage:  j = agen(a, di, ord,typ)  
 
 Input:

  a                      vector 
                         
  di                     integer, dimension of time series 
                         
  ord                    integer, order of series 
                         
  typ                    integer, describing the model type 
                         
 Output:

  j                      matrix 
                         
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(C) MD*TECH Method and Data Technologies, 17.8.2000
