```      SUBROUTINE CUNMBR( VECT, SIDE, TRANS, M, N, K, A, LDA, TAU, C,
\$                   LDC, WORK, LWORK, INFO )
*
*  -- LAPACK routine (version 3.1) --
*     Univ. of Tennessee, Univ. of California Berkeley and NAG Ltd..
*     November 2006
*
*     .. Scalar Arguments ..
CHARACTER          SIDE, TRANS, VECT
INTEGER            INFO, K, LDA, LDC, LWORK, M, N
*     ..
*     .. Array Arguments ..
COMPLEX            A( LDA, * ), C( LDC, * ), TAU( * ),
\$                   WORK( * )
*     ..
*
*  Purpose
*  =======
*
*  If VECT = 'Q', CUNMBR overwrites the general complex M-by-N matrix C
*  with
*                  SIDE = 'L'     SIDE = 'R'
*  TRANS = 'N':      Q * C          C * Q
*  TRANS = 'C':      Q**H * C       C * Q**H
*
*  If VECT = 'P', CUNMBR overwrites the general complex M-by-N matrix C
*  with
*                  SIDE = 'L'     SIDE = 'R'
*  TRANS = 'N':      P * C          C * P
*  TRANS = 'C':      P**H * C       C * P**H
*
*  Here Q and P**H are the unitary matrices determined by CGEBRD 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) and
*  G(i) respectively.
*
*  Let nq = m if SIDE = 'L' and nq = n if SIDE = 'R'. Thus nq is the
*  order of the unitary matrix Q or P**H that is applied.
*
*  If VECT = 'Q', A is assumed to have been an NQ-by-K matrix:
*  if nq >= k, Q = H(1) H(2) . . . H(k);
*  if nq < k, Q = H(1) H(2) . . . H(nq-1).
*
*  If VECT = 'P', A is assumed to have been a K-by-NQ matrix:
*  if k < nq, P = G(1) G(2) . . . G(k);
*  if k >= nq, P = G(1) G(2) . . . G(nq-1).
*
*  Arguments
*  =========
*
*  VECT    (input) CHARACTER*1
*          = 'Q': apply Q or Q**H;
*          = 'P': apply P or P**H.
*
*  SIDE    (input) CHARACTER*1
*          = 'L': apply Q, Q**H, P or P**H from the Left;
*          = 'R': apply Q, Q**H, P or P**H from the Right.
*
*  TRANS   (input) CHARACTER*1
*          = 'N':  No transpose, apply Q or P;
*          = 'C':  Conjugate transpose, apply Q**H or P**H.
*
*  M       (input) INTEGER
*          The number of rows of the matrix C. M >= 0.
*
*  N       (input) INTEGER
*          The number of columns of the matrix C. N >= 0.
*
*  K       (input) INTEGER
*          If VECT = 'Q', the number of columns in the original
*          matrix reduced by CGEBRD.
*          If VECT = 'P', the number of rows in the original
*          matrix reduced by CGEBRD.
*          K >= 0.
*
*  A       (input) COMPLEX array, dimension
*                                (LDA,min(nq,K)) if VECT = 'Q'
*                                (LDA,nq)        if VECT = 'P'
*          The vectors which define the elementary reflectors H(i) and
*          G(i), whose products determine the matrices Q and P, as
*          returned by CGEBRD.
*
*  LDA     (input) INTEGER
*          The leading dimension of the array A.
*          If VECT = 'Q', LDA >= max(1,nq);
*          if VECT = 'P', LDA >= max(1,min(nq,K)).
*
*  TAU     (input) COMPLEX array, dimension (min(nq,K))
*          TAU(i) must contain the scalar factor of the elementary
*          reflector H(i) or G(i) which determines Q or P, as returned
*          by CGEBRD in the array argument TAUQ or TAUP.
*
*  C       (input/output) COMPLEX array, dimension (LDC,N)
*          On entry, the M-by-N matrix C.
*          On exit, C is overwritten by Q*C or Q**H*C or C*Q**H or C*Q
*          or P*C or P**H*C or C*P or C*P**H.
*
*  LDC     (input) INTEGER
*          The leading dimension of the array C. LDC >= max(1,M).
*
*  WORK    (workspace/output) COMPLEX array, dimension (MAX(1,LWORK))
*          On exit, if INFO = 0, WORK(1) returns the optimal LWORK.
*
*  LWORK   (input) INTEGER
*          The dimension of the array WORK.
*          If SIDE = 'L', LWORK >= max(1,N);
*          if SIDE = 'R', LWORK >= max(1,M);
*          if N = 0 or M = 0, LWORK >= 1.
*          For optimum performance LWORK >= max(1,N*NB) if SIDE = 'L',
*          and LWORK >= max(1,M*NB) if SIDE = 'R', where NB is the
*          optimal blocksize. (NB = 0 if M = 0 or N = 0.)
*
*          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    (output) INTEGER
*          = 0:  successful exit
*          < 0:  if INFO = -i, the i-th argument had an illegal value
*
*  =====================================================================
*
*     .. Local Scalars ..
LOGICAL            APPLYQ, LEFT, LQUERY, NOTRAN
CHARACTER          TRANST
INTEGER            I1, I2, IINFO, LWKOPT, MI, NB, NI, NQ, NW
*     ..
*     .. External Functions ..
LOGICAL            LSAME
INTEGER            ILAENV
EXTERNAL           ILAENV, LSAME
*     ..
*     .. External Subroutines ..
EXTERNAL           CUNMLQ, CUNMQR, XERBLA
*     ..
*     .. Intrinsic Functions ..
INTRINSIC          MAX, MIN
*     ..
*     .. Executable Statements ..
*
*     Test the input arguments
*
INFO = 0
APPLYQ = LSAME( VECT, 'Q' )
LEFT = LSAME( SIDE, 'L' )
NOTRAN = LSAME( TRANS, 'N' )
LQUERY = ( LWORK.EQ.-1 )
*
*     NQ is the order of Q or P and NW is the minimum dimension of WORK
*
IF( LEFT ) THEN
NQ = M
NW = N
ELSE
NQ = N
NW = M
END IF
IF( M.EQ.0 .OR. N.EQ.0 ) THEN
NW = 0
END IF
IF( .NOT.APPLYQ .AND. .NOT.LSAME( VECT, 'P' ) ) THEN
INFO = -1
ELSE IF( .NOT.LEFT .AND. .NOT.LSAME( SIDE, 'R' ) ) THEN
INFO = -2
ELSE IF( .NOT.NOTRAN .AND. .NOT.LSAME( TRANS, 'C' ) ) THEN
INFO = -3
ELSE IF( M.LT.0 ) THEN
INFO = -4
ELSE IF( N.LT.0 ) THEN
INFO = -5
ELSE IF( K.LT.0 ) THEN
INFO = -6
ELSE IF( ( APPLYQ .AND. LDA.LT.MAX( 1, NQ ) ) .OR.
\$         ( .NOT.APPLYQ .AND. LDA.LT.MAX( 1, MIN( NQ, K ) ) ) )
\$          THEN
INFO = -8
ELSE IF( LDC.LT.MAX( 1, M ) ) THEN
INFO = -11
ELSE IF( LWORK.LT.MAX( 1, NW ) .AND. .NOT.LQUERY ) THEN
INFO = -13
END IF
*
IF( INFO.EQ.0 ) THEN
IF( NW.GT.0 ) THEN
IF( APPLYQ ) THEN
IF( LEFT ) THEN
NB = ILAENV( 1, 'CUNMQR', SIDE // TRANS, M-1, N, M-1,
\$                         -1 )
ELSE
NB = ILAENV( 1, 'CUNMQR', SIDE // TRANS, M, N-1, N-1,
\$                         -1 )
END IF
ELSE
IF( LEFT ) THEN
NB = ILAENV( 1, 'CUNMLQ', SIDE // TRANS, M-1, N, M-1,
\$                         -1 )
ELSE
NB = ILAENV( 1, 'CUNMLQ', SIDE // TRANS, M, N-1, N-1,
\$                         -1 )
END IF
END IF
LWKOPT = MAX( 1, NW*NB )
ELSE
LWKOPT = 1
END IF
WORK( 1 ) = LWKOPT
END IF
*
IF( INFO.NE.0 ) THEN
CALL XERBLA( 'CUNMBR', -INFO )
RETURN
ELSE IF( LQUERY ) THEN
RETURN
END IF
*
*     Quick return if possible
*
IF( M.EQ.0 .OR. N.EQ.0 )
\$   RETURN
*
IF( APPLYQ ) THEN
*
*        Apply Q
*
IF( NQ.GE.K ) THEN
*
*           Q was determined by a call to CGEBRD with nq >= k
*
CALL CUNMQR( SIDE, TRANS, M, N, K, A, LDA, TAU, C, LDC,
\$                   WORK, LWORK, IINFO )
ELSE IF( NQ.GT.1 ) THEN
*
*           Q was determined by a call to CGEBRD with nq < k
*
IF( LEFT ) THEN
MI = M - 1
NI = N
I1 = 2
I2 = 1
ELSE
MI = M
NI = N - 1
I1 = 1
I2 = 2
END IF
CALL CUNMQR( SIDE, TRANS, MI, NI, NQ-1, A( 2, 1 ), LDA, TAU,
\$                   C( I1, I2 ), LDC, WORK, LWORK, IINFO )
END IF
ELSE
*
*        Apply P
*
IF( NOTRAN ) THEN
TRANST = 'C'
ELSE
TRANST = 'N'
END IF
IF( NQ.GT.K ) THEN
*
*           P was determined by a call to CGEBRD with nq > k
*
CALL CUNMLQ( SIDE, TRANST, M, N, K, A, LDA, TAU, C, LDC,
\$                   WORK, LWORK, IINFO )
ELSE IF( NQ.GT.1 ) THEN
*
*           P was determined by a call to CGEBRD with nq <= k
*
IF( LEFT ) THEN
MI = M - 1
NI = N
I1 = 2
I2 = 1
ELSE
MI = M
NI = N - 1
I1 = 1
I2 = 2
END IF
CALL CUNMLQ( SIDE, TRANST, MI, NI, NQ-1, A( 1, 2 ), LDA,
\$                   TAU, C( I1, I2 ), LDC, WORK, LWORK, IINFO )
END IF
END IF
WORK( 1 ) = LWKOPT
RETURN
*
*     End of CUNMBR
*
END

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