to the ordered generalized real Schur form (S,T).
          That is,

                 (U   U  )
                 ( 11  12)
             U = (       ),
                 (U   U  )
                 ( 21  22)

          where U  , U  , U   and U   are N-by-N matrices.
                 11   12   21      22
          If JOBB = 'B' and SCAL = 'G', then U corresponds to the
          scaled pencil. If a basis for the stable deflating
          subspace of the original problem is needed, then the
          submatri