rix A,
          and the elements below the diagonal are not referenced.
          On exit, the leading P-by-N part (upper trapezoidal or
          triangular, if UPLO = 'U') of this array contains the
          trailing components (the vectors v, see Method) of the
          elementary reflectors used in the factorization.

  LDA     INTEGER
          The leading dimension of array A.  LDA &gt;= MAX(1,P).

  B       (input/output) DOUBLE PRECISION array, dimension (LDB,M)
          On entry, the leading P-