 on entry.
          If TOL2 &gt; 0 and ORDSEL = 'A', then TOL2 &lt;= TOL1.
          TOL2 &lt; 1.

</PRE>
<B>Workspace</B>
<PRE>
  IWORK   INTEGER array, dimension (MAX(1,2*N))
          On exit with INFO = 0, IWORK(1) contains the order of the
          minimal realization of the system.

  DWORK   DOUBLE PRECISION array, dimension (LDWORK)
          On exit, if INFO = 0, DWORK(1) returns the optimal value
          of LDWORK and DWORK(2) contains RCOND, the reciprocal
          condition number of the U1