SE.
                  (LDB,N)     if LTRB = .TRUE.
          On entry with LTRB = .FALSE., the leading N-by-(K+N) part
          of this array must contain the matrix B.
          On entry with LTRB = .TRUE., the leading (K+N)-by-N part
          of this array must contain the matrix B.
          On exit with LTRB = .FALSE., the leading N-by-(K+N) part
          of this array contains the matrix Bout and, in the zero
          parts, information about the elementary reflectors used to
          compute the 