be either
          1 or -1.

  A       (input/output)  DOUBLE PRECISION array, dimension
                          (LDA1,LDA2,K)
          On entry, the leading N-by-N-by-K part of this array
          must contain the factors in upper Hessenberg-triangular
          form, that is, A(:,:,H) is upper Hessenberg and the other
          factors are upper triangular.
          On exit, if JOB = 'S' and INFO = 0, the leading
          N-by-N-by-K part of this array contains the factors of
          A in periodi