reshold used might be
                unsuitable.

</PRE>
<A name="Method"><B><FONT SIZE="+1">Method</FONT></B></A>
<PRE>
  The routine implements the method presented in [2], which is an
  extension of the method in [1] for descriptor systems. There are
  several improvements and refinements [3-5] to increase numerical
  robustness, accuracy and efficiency, such as the usage of
  structure-preserving eigenvalue computations for skew-Hamiltonian/
  Hamiltonian eigenvalue problems in the iterative method in 