 if INFO = 0, or INFO = 1, DWORK(1) returns the
          optimal value of LDWORK.

  LDWORK  INTEGER
          The length of the array DWORK. LDWORK &gt;= MAX(1,4*N).
          For optimum performance LDWORK should sometimes be larger.

</PRE>
<B>Error Indicator</B>
<PRE>
  INFO    INTEGER
          = 0:  successful exit;
          &lt; 0:  if INFO = -i, the i-th argument had an illegal
                value;
          = 1:  if the Lyapunov equation is (nearly) singular
                (warning indicator);