ZUNGBR generates one of the complex unitary matrices Q or P**H


 determined by ZGEBRD when reducing a complex matrix A to bidiagonal


 form: A = Q * B * P**H.  Q and P**H are defined as products of


 elementary reflectors H(i) or G(i) respectively.


 If VECT = 'Q', A is assumed to have been an M-by-K matrix, and Q


 is of order M:


 if m >= k, Q = H(1) H(2) . . . H(k) and ZUNGBR returns the first n


 columns of Q, where m >= n >= k;


 if m < k, Q = H(1) H(2) . . . H(m-1) and ZUNGBR returns Q as an


 M-by-M matrix.


 If VECT = 'P', A is assumed to have been a K-by-N matrix, and P**H


 is of order N:


 if k < n, P**H = G(k) . . . G(2) G(1) and ZUNGBR returns the first m


 rows of P**H, where n >= m >= k;


 if k >= n, P**H = G(n-1) . . . G(2) G(1) and ZUNGBR returns P**H as


 an N-by-N matrix.

VECT

          VECT is CHARACTER*1


          Specifies whether the matrix Q or the matrix P**H is


          required, as defined in the transformation applied by ZGEBRD:


          = 'Q':  generate Q;


          = 'P':  generate P**H.

M

          M is INTEGER


          The number of rows of the matrix Q or P**H to be returned.


          M >= 0.

N

          N is INTEGER


          The number of columns of the matrix Q or P**H to be returned.


          N >= 0.


          If VECT = 'Q', M >= N >= min(M,K);


          if VECT = 'P', N >= M >= min(N,K).

K

          K is INTEGER


          If VECT = 'Q', the number of columns in the original M-by-K


          matrix reduced by ZGEBRD.


          If VECT = 'P', the number of rows in the original K-by-N


          matrix reduced by ZGEBRD.


          K >= 0.

A

          A is COMPLEX*16 array, dimension (LDA,N)


          On entry, the vectors which define the elementary reflectors,


          as returned by ZGEBRD.


          On exit, the M-by-N matrix Q or P**H.

LDA

          LDA is INTEGER


          The leading dimension of the array A. LDA >= M.

TAU

          TAU is COMPLEX*16 array, dimension


                                (min(M,K)) if VECT = 'Q'


                                (min(N,K)) if VECT = 'P'


          TAU(i) must contain the scalar factor of the elementary


          reflector H(i) or G(i), which determines Q or P**H, as


          returned by ZGEBRD in its array argument TAUQ or TAUP.

WORK

          WORK is COMPLEX*16 array, dimension (MAX(1,LWORK))


          On exit, if INFO = 0, WORK(1) returns the optimal LWORK.

LWORK

          LWORK is INTEGER


          The dimension of the array WORK. LWORK >= max(1,min(M,N)).


          For optimum performance LWORK >= min(M,N)*NB, where NB


          is the optimal blocksize.


          If LWORK = -1, then a workspace query is assumed; the routine


          only calculates the optimal size of the WORK array, returns


          this value as the first entry of the WORK array, and no error


          message related to LWORK is issued by XERBLA.

INFO

          INFO is INTEGER


          = 0:  successful exit


          < 0:  if INFO = -i, the i-th argument had an illegal value

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NAG Ltd.

April 2012