hogonal matrix Z used to transform B' to real upper
          Schur form.

  LDZ     INTEGER
          The leading dimension of array Z.  LDZ &gt;= MAX(1,M).

</PRE>
<B>Workspace</B>
<PRE>
  IWORK   INTEGER array, dimension (4*N)

  DWORK   DOUBLE PRECISION array, dimension (LDWORK)
          On exit, if INFO = 0, DWORK(1) returns the optimal value
          of LDWORK, and DWORK(2), DWORK(3),..., DWORK(N) contain
          the scalar factors of the elementary reflectors used to
          reduce A to upper H