-K must
          contain the negative generator of the Schur complement of
          the leading P*K-by-P*K part in T, computed from previous
          calls of this routine.
          On exit, if INFO = 0, then the leading K-by-(N-P)*K /
          (N-P)*K-by-K part of this array contains, in the first
          K-by-K block, the upper / lower Cholesky factor of
          T(1:K,1:K), in the following S-1 K-by-K blocks, the
          Householder transformations applied during the process,
          and in t