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*
* Definition:
* ===========
*
* SUBROUTINE ZGEMLQ( SIDE, TRANS, M, N, K, A, LDA, WORK1,
* $ LWORK1, C, LDC, WORK2, LWORK2, INFO )
*
*
* .. Scalar Arguments ..
* CHARACTER SIDE, TRANS
* INTEGER INFO, LDA, M, N, K, MB, NB, LWORK1, LWORK2, LDC
* ..
* .. Array Arguments ..
* COMPLEX*16 A( LDA, * ), WORK1( * ), C(LDC, * ),
* $ WORK2( * )
*> \par Purpose:
* =============
*>
*> \verbatim
*>
*> ZGEMLQ overwrites the general real M-by-N matrix C with
*>
*>
*> SIDE = 'L' SIDE = 'R'
*> TRANS = 'N': Q * C C * Q
*> TRANS = 'T': Q**T * C C * Q**T
*> where Q is a complex orthogonal matrix defined as the product
*> of blocked elementary reflectors computed by short wide LQ
*> factorization (DGELQ)
*> \endverbatim
*
* Arguments:
* ==========
*
*> \param[in] SIDE
*> SIDE is CHARACTER*1
*> = 'L': apply Q or Q**T from the Left;
*> = 'R': apply Q or Q**T from the Right.
*>
*> \param[in] TRANS
*> TRANS is CHARACTER*1
*> = 'N': No transpose, apply Q;
*> = 'T': Transpose, apply Q**T.
*> \param[in] M
*> \verbatim
*> M is INTEGER
*> The number of rows of the matrix A. M >=0.
*> \endverbatim
*>
*> \param[in] N
*> \verbatim
*> N is INTEGER
*> The number of columns of the matrix C. N >= M.
*> \endverbatim
*>
*> \param[in] K
*> \verbatim
*> K is INTEGER
*> The number of elementary reflectors whose product defines
*> the matrix Q.
*> M >= K >= 0;
*>
*> \endverbatim
*>
*> \param[in,out] A
*> \verbatim
*> A is COMPLEX*16 array, dimension (LDA,K)
*> The i-th row must contain the vector which defines the blocked
*> elementary reflector H(i), for i = 1,2,...,k, as returned by
*> DLASWLQ in the first k rows of its array argument A.
*> \endverbatim
*>
*> \param[in] LDA
*> \verbatim
*> LDA is INTEGER
*> The leading dimension of the array A.
*> If SIDE = 'L', LDA >= max(1,M);
*> if SIDE = 'R', LDA >= max(1,N).
*> \endverbatim
*>
*> \param[in] WORK1
*> \verbatim
*> WORK1 is COMPLEX*16 array, dimension (MAX(1,LWORK1)) is
*> returned by GEQR.
*> \endverbatim
*>
*> \param[in] LWORK1
*> \verbatim
*> LWORK1 is INTEGER
*> The dimension of the array WORK1.
*> \endverbatim
*>
*> \param[in,out] C
*> C is COMPLEX*16 array, dimension (LDC,N)
*> On entry, the M-by-N matrix C.
*> On exit, C is overwritten by Q*C or Q**T*C or C*Q**T or C*Q.
*> \param[in] LDC
*> LDC is INTEGER
*> The leading dimension of the array C. LDC >= max(1,M).
*>
*> \param[out] WORK2
*> \verbatim
*> (workspace) COMPLEX*16 array, dimension (MAX(1,LWORK2))
*>
*> \endverbatim
*> \param[in] LWORK2
*> \verbatim
*> LWORK2 is INTEGER
*> The dimension of the array WORK2.
*> If LWORK2 = -1, then a workspace query is assumed; the routine
*> only calculates the optimal size of the WORK2 array, returns
*> this value as the third entry of the WORK2 array (WORK2(1)),
*> and no error message related to LWORK2 is issued by XERBLA.
*>
*> \endverbatim
*> \param[out] INFO
*> \verbatim
*> INFO is INTEGER
*> = 0: successful exit
*> < 0: if INFO = -i, the i-th argument had an illegal value
*> \endverbatim
*
* Authors:
* ========
*
*> \author Univ. of Tennessee
*> \author Univ. of California Berkeley
*> \author Univ. of Colorado Denver
*> \author NAG Ltd.
*
*> \par Further Details:
* =====================
*>
*> \verbatim
*> Depending on the matrix dimensions M and N, and row and column
*> block sizes MB and NB returned by ILAENV, GELQ will use either
*> LASWLQ(if the matrix is short-and-wide) or GELQT to compute
*> the LQ decomposition.
*> The output of LASWLQ or GELQT representing Q is stored in A and in
*> array WORK1(6:LWORK1) for later use.
*> WORK1(2:5) contains the matrix dimensions M,N and block sizes MB, NB
*> which are needed to interpret A and WORK1(6:LWORK1) for later use.
*> WORK1(1)=1 indicates that the code needed to take WORK1(2:5) and
*> decide whether LASWLQ or GELQT was used is the same as used below in
*> GELQ. For a detailed description of A and WORK1(6:LWORK1), see
*> Further Details in LASWLQ or GELQT.
*> \endverbatim
*>
* =====================================================================
SUBROUTINE ZGEMLQ( SIDE, TRANS, M, N, K, A, LDA, WORK1, LWORK1,
$ C, LDC, WORK2, LWORK2, INFO )
*
* -- LAPACK computational routine (version 3.5.0) --
* -- LAPACK is a software package provided by Univ. of Tennessee, --
* -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
* November 2013
*
* .. Scalar Arguments ..
CHARACTER SIDE, TRANS
INTEGER INFO, LDA, M, N, K, LWORK1, LWORK2, LDC
* ..
* .. Array Arguments ..
COMPLEX*16 A( LDA, * ), C( LDC, * ), WORK1( * ), WORK2( * )
* ..
*
* =====================================================================
*
* ..
* .. Local Scalars ..
LOGICAL LEFT, RIGHT, TRAN, NOTRAN, LQUERY
INTEGER I, II, KK, MB, NB, LW, NBLCKS, MN
* ..
* .. External Functions ..
LOGICAL LSAME
EXTERNAL LSAME
* .. External Subroutines ..
EXTERNAL ZLAMSWLQ, ZGEMLQT, XERBLA
* .. Intrinsic Functions ..
INTRINSIC INT, MAX, MIN, MOD
* ..
* .. Executable Statements ..
*
* Test the input arguments
*
LQUERY = LWORK2.LT.0
NOTRAN = LSAME( TRANS, 'N' )
TRAN = LSAME( TRANS, 'C' )
LEFT = LSAME( SIDE, 'L' )
RIGHT = LSAME( SIDE, 'R' )
*
MB = INT(WORK1(4))
NB = INT(WORK1(5))
IF (LEFT) THEN
LW = N * MB
MN = M
ELSE
LW = M * MB
MN = N
END IF
IF ((NB.GT.K).AND.(MN.GT.K)) THEN
IF(MOD(MN-K, NB-K).EQ.0) THEN
NBLCKS = (MN-K)/(NB-K)
ELSE
NBLCKS = (MN-K)/(NB-K) + 1
END IF
ELSE
NBLCKS = 1
END IF
*
INFO = 0
IF( .NOT.LEFT .AND. .NOT.RIGHT ) THEN
INFO = -1
ELSE IF( .NOT.TRAN .AND. .NOT.NOTRAN ) THEN
INFO = -2
ELSE IF( M.LT.0 ) THEN
INFO = -3
ELSE IF( N.LT.0) THEN
INFO = -4
ELSE IF( K.LT.0 ) THEN
INFO = -5
ELSE IF( LDA.LT.MAX( 1, K ) ) THEN
INFO = -7
ELSE IF( LWORK1.LT.MAX( 1, MB*K*NBLCKS+5 )) THEN
INFO = -9
ELSE IF( LDC.LT.MAX( 1, M ) ) THEN
INFO = -11
ELSE IF(( LWORK2.LT.MAX(1,LW)).AND.(.NOT.LQUERY)) THEN
INFO = -13
END IF
*
IF( INFO.EQ.0) THEN
WORK2(1) = LW
END IF
IF( INFO.NE.0 ) THEN
CALL XERBLA( 'ZGEMLQ', -INFO )
RETURN
ELSE IF (LQUERY) THEN
RETURN
END IF
*
* Quick return if possible
*
IF( MIN(M,N,K).EQ.0 ) THEN
RETURN
END IF
*
IF((LEFT.AND.M.LE.K).OR.(RIGHT.AND.N.LE.K).OR.(NB.LE.K).OR.
$ (NB.GE.MAX(M,N,K))) THEN
CALL ZGEMLQT( SIDE, TRANS, M, N, K, MB, A, LDA,
$ WORK1(6), MB, C, LDC, WORK2, INFO)
ELSE
CALL ZLAMSWLQ( SIDE, TRANS, M, N, K, MB, NB, A, LDA, WORK1(6),
$ MB, C, LDC, WORK2, LWORK2, INFO )
END IF
*
WORK2(1) = LW
RETURN
*
* End of ZGEMLQ
*
END
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