 = N        :  some eigenvalues might be inaccurate;
          = N+1      :  some eigenvalues might be inaccurate, and
                        details can be found in IWORK.

</PRE>
<B>Error Indicator</B>
<PRE>
  INFO    INTEGER
          = 0      :  succesful exit;
          &lt; 0      :  if INFO = -i, the i-th argument had an illegal
                      value;
          = 1,..,N :  the periodic QZ iteration did not converge.
                      A is not in periodic Schur form, but
                   