 array
          contains the upper triangular matrix R (as defined in
          METHOD), and the M-by-MIN(M,N) strictly lower triangular
          part together with the elements of the array TAU are
          overwritten by details of the matrix P (also defined in
          METHOD). When M &lt; N, columns (M+1),...,N of the array B
          are overwritten by the matrix Z (see METHOD).
          On exit, if LTRANS = .TRUE., the leading
          MIN(M,N)-by-MIN(M,N) upper triangular part of
          B(1