 Usage:  y = genar(x, startval, alpha )  
 
 Input:

  x                      n x 1 vector of exogenous variables plus noise 
                         
  startval               p x 1 vector of starting values 
                         
  alpha                  p x 1 vector of parameters 
                         
 Output:

  y                      n x 1 vector 
                         
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(C) MD*TECH Method and Data Technologies, 17.8.2000
