rts of these elements
          are zero. The strictly lower triangular part is used as
          workspace. The matrix B is assumed nonzero.
          On exit, the leading N-by-N upper triangular part of this
          array contains the computed upper triangular block-
          diagonal matrix, corresponding to the given matrix B. The
          remaining part is set to zero. The diagonal elements of B
          are real non-negative.

  LDB     INTEGER
          The leading dimension of the array B.  LDB