a system with NU ALPHA-unstable eigenvalues and
          NS ALPHA-stable eigenvalues (NU+NS = N), the leading
          NU-by-NU block contains the unreduced part of A
          corresponding to ALPHA-unstable eigenvalues in an
          upper real Schur form.
          The trailing (NR+NS-N)-by-(NR+NS-N) block contains
          the reduced part of A corresponding to ALPHA-stable
          eigenvalues.

  LDA     INTEGER
          The leading dimension of array A.  LDA &gt;= MAX(1,N).

  B       (input/ou