atrix B.  M &gt;= 0.

  A       (input/output) DOUBLE PRECISION array, dimension (LDA,N)
          On entry, the leading N-by-N part of this array must
          contain the coefficient matrix A of the equation.
          On exit, the leading N-by-N upper Hessenberg part of this
          array contains the matrix H, and the remainder of the
          leading N-by-N part, together with the elements 2,3,...,N
          of array DWORK, contain the orthogonal transformation
          matrix U (stored in factor