CUNG2R generates an m by n complex matrix Q with orthonormal columns,
 which is defined as the first n columns of a product of k elementary
 reflectors of order m

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

 as returned by CGEQRF.

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

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

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

          A is COMPLEX array, dimension (LDA,N)
          On entry, the i-th column must contain the vector which
          defines the elementary reflector H(i), for i = 1,2,...,k, as
          returned by CGEQRF in the first k columns 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 COMPLEX array, dimension (K)
          TAU(i) must contain the scalar factor of the elementary
          reflector H(i), as returned by CGEQRF.

          WORK is COMPLEX array, dimension (N)

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