g to
                compute the zeros of a transfer function;
          = 2:  the QR algorithm failed to converge when trying to
                compute the poles of a transfer function.
                The errors INFO = 1 or 2 are unlikely to appear.

</PRE>
<A name="Method"><B><FONT SIZE="+1">Method</FONT></B></A>
<PRE>
  The routine implements the pole-zero method proposed in [1].
  This method is based on an algorithm for computing the transfer
  function of a single-input single-output (SISO) system.
