```      SUBROUTINE CUNMTR( SIDE, UPLO, TRANS, M, N, 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, UPLO
INTEGER            INFO, LDA, LDC, LWORK, M, N
*     ..
*     .. Array Arguments ..
COMPLEX            A( LDA, * ), C( LDC, * ), TAU( * ),
\$                   WORK( * )
*     ..
*
*  Purpose
*  =======
*
*  CUNMTR 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
*
*  where Q is a complex unitary matrix of order nq, with nq = m if
*  SIDE = 'L' and nq = n if SIDE = 'R'. Q is defined as the product of
*  nq-1 elementary reflectors, as returned by CHETRD:
*
*  if UPLO = 'U', Q = H(nq-1) . . . H(2) H(1);
*
*  if UPLO = 'L', Q = H(1) H(2) . . . H(nq-1).
*
*  Arguments
*  =========
*
*  SIDE    (input) CHARACTER*1
*          = 'L': apply Q or Q**H from the Left;
*          = 'R': apply Q or Q**H from the Right.
*
*  UPLO    (input) CHARACTER*1
*          = 'U': Upper triangle of A contains elementary reflectors
*                 from CHETRD;
*          = 'L': Lower triangle of A contains elementary reflectors
*                 from CHETRD.
*
*  TRANS   (input) CHARACTER*1
*          = 'N':  No transpose, apply Q;
*          = 'C':  Conjugate transpose, apply Q**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.
*
*  A       (input) COMPLEX array, dimension
*                               (LDA,M) if SIDE = 'L'
*                               (LDA,N) if SIDE = 'R'
*          The vectors which define the elementary reflectors, as
*          returned by CHETRD.
*
*  LDA     (input) INTEGER
*          The leading dimension of the array A.
*          LDA >= max(1,M) if SIDE = 'L'; LDA >= max(1,N) if SIDE = 'R'.
*
*  TAU     (input) COMPLEX array, dimension
*                               (M-1) if SIDE = 'L'
*                               (N-1) if SIDE = 'R'
*          TAU(i) must contain the scalar factor of the elementary
*          reflector H(i), as returned by CHETRD.
*
*  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.
*
*  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).
*          For optimum performance LWORK >= N*NB if SIDE = 'L', and
*          LWORK >=M*NB if SIDE = 'R', 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    (output) INTEGER
*          = 0:  successful exit
*          < 0:  if INFO = -i, the i-th argument had an illegal value
*
*  =====================================================================
*
*     .. Local Scalars ..
LOGICAL            LEFT, LQUERY, UPPER
INTEGER            I1, I2, IINFO, LWKOPT, MI, NB, NI, NQ, NW
*     ..
*     .. External Functions ..
LOGICAL            LSAME
INTEGER            ILAENV
EXTERNAL           ILAENV, LSAME
*     ..
*     .. External Subroutines ..
EXTERNAL           CUNMQL, CUNMQR, XERBLA
*     ..
*     .. Intrinsic Functions ..
INTRINSIC          MAX
*     ..
*     .. Executable Statements ..
*
*     Test the input arguments
*
INFO = 0
LEFT = LSAME( SIDE, 'L' )
UPPER = LSAME( UPLO, 'U' )
LQUERY = ( LWORK.EQ.-1 )
*
*     NQ is the order of Q and NW is the minimum dimension of WORK
*
IF( LEFT ) THEN
NQ = M
NW = N
ELSE
NQ = N
NW = M
END IF
IF( .NOT.LEFT .AND. .NOT.LSAME( SIDE, 'R' ) ) THEN
INFO = -1
ELSE IF( .NOT.UPPER .AND. .NOT.LSAME( UPLO, 'L' ) ) THEN
INFO = -2
ELSE IF( .NOT.LSAME( TRANS, 'N' ) .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( LDA.LT.MAX( 1, NQ ) ) THEN
INFO = -7
ELSE IF( LDC.LT.MAX( 1, M ) ) THEN
INFO = -10
ELSE IF( LWORK.LT.MAX( 1, NW ) .AND. .NOT.LQUERY ) THEN
INFO = -12
END IF
*
IF( INFO.EQ.0 ) THEN
IF( UPPER ) THEN
IF( LEFT ) THEN
NB = ILAENV( 1, 'CUNMQL', SIDE // TRANS, M-1, N, M-1,
\$                      -1 )
ELSE
NB = ILAENV( 1, 'CUNMQL', SIDE // TRANS, M, N-1, N-1,
\$                      -1 )
END IF
ELSE
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
END IF
LWKOPT = MAX( 1, NW )*NB
WORK( 1 ) = LWKOPT
END IF
*
IF( INFO.NE.0 ) THEN
CALL XERBLA( 'CUNMTR', -INFO )
RETURN
ELSE IF( LQUERY ) THEN
RETURN
END IF
*
*     Quick return if possible
*
IF( M.EQ.0 .OR. N.EQ.0 .OR. NQ.EQ.1 ) THEN
WORK( 1 ) = 1
RETURN
END IF
*
IF( LEFT ) THEN
MI = M - 1
NI = N
ELSE
MI = M
NI = N - 1
END IF
*
IF( UPPER ) THEN
*
*        Q was determined by a call to CHETRD with UPLO = 'U'
*
CALL CUNMQL( SIDE, TRANS, MI, NI, NQ-1, A( 1, 2 ), LDA, TAU, C,
\$                LDC, WORK, LWORK, IINFO )
ELSE
*
*        Q was determined by a call to CHETRD with UPLO = 'L'
*
IF( LEFT ) THEN
I1 = 2
I2 = 1
ELSE
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
WORK( 1 ) = LWKOPT
RETURN
*
*     End of CUNMTR
*
END

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