 BETA = 0 means a pure relative error method and can be
          used only if rank(D) = P.

  A       (input/output) DOUBLE PRECISION array, dimension (LDA,N)
          On entry, the leading N-by-N part of this array must
          contain the state dynamics matrix A.
          On exit, if INFO = 0, the leading NR-by-NR part of this
          array contains the state dynamics matrix Ar of the reduced
          order system.
          The resulting A has a block-diagonal form with two blocks.
          For 