DORGR2 generates an m by n real matrix Q with orthonormal rows,
 which is defined as the last m rows of a product of k elementary
 reflectors of order n

       Q  =  H(1) H(2) . . . H(k)

 as returned by DGERQF.

          M is INTEGER
          The number of rows of the matrix Q. M >= 0.

          N is INTEGER
          The number of columns of the matrix Q. N >= M.

          K is INTEGER
          The number of elementary reflectors whose product defines the
          matrix Q. M >= K >= 0.

          A is DOUBLE PRECISION array, dimension (LDA,N)
          On entry, the (m-k+i)-th row must contain the vector which
          defines the elementary reflector H(i), for i = 1,2,...,k, as
          returned by DGERQF in the last k rows of its array argument
          A.
          On exit, the m by n matrix Q.

          LDA is INTEGER
          The first dimension of the array A. LDA >= max(1,M).

          TAU is DOUBLE PRECISION array, dimension (K)
          TAU(i) must contain the scalar factor of the elementary
          reflector H(i), as returned by DGERQF.

          WORK is DOUBLE PRECISION array, dimension (M)

          INFO is INTEGER
          = 0: successful exit
          < 0: if INFO = -i, the i-th argument has an illegal value