fails, an eigenvalue of
  (A  , B  ) closest to the mean of those of (A  , B  ) is selected,
    22   22                                    11   11
  and moved by unitary equivalence transformations in the leading
  position of (A  , B  ); the moved diagonal elements in A and B are
                22   22
  then added to the blocks A   and B  , respectively, increasing
                            11      11
  their order by 1. Another attempt is made to compute suitable
  transformation matrices X and Y wit