710 lines
21 KiB
Fortran
710 lines
21 KiB
Fortran
*> \brief \b DLARFB applies a block reflector or its transpose to a general rectangular matrix.
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*
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* =========== DOCUMENTATION ===========
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*
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* Online html documentation available at
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* http://www.netlib.org/lapack/explore-html/
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*
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*> \htmlonly
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*> Download DLARFB + dependencies
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*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.tgz?format=tgz&filename=/lapack/lapack_routine/dlarfb.f">
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*> [TGZ]</a>
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*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.zip?format=zip&filename=/lapack/lapack_routine/dlarfb.f">
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*> [ZIP]</a>
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*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.txt?format=txt&filename=/lapack/lapack_routine/dlarfb.f">
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*> [TXT]</a>
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*> \endhtmlonly
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*
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* Definition:
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* ===========
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*
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* SUBROUTINE DLARFB( SIDE, TRANS, DIRECT, STOREV, M, N, K, V, LDV,
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* T, LDT, C, LDC, WORK, LDWORK )
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*
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* .. Scalar Arguments ..
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* CHARACTER DIRECT, SIDE, STOREV, TRANS
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* INTEGER K, LDC, LDT, LDV, LDWORK, M, N
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* ..
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* .. Array Arguments ..
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* DOUBLE PRECISION C( LDC, * ), T( LDT, * ), V( LDV, * ),
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* $ WORK( LDWORK, * )
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* ..
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*
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*
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*> \par Purpose:
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* =============
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*>
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*> \verbatim
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*>
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*> DLARFB applies a real block reflector H or its transpose H**T to a
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*> real m by n matrix C, from either the left or the right.
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*> \endverbatim
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*
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* Arguments:
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* ==========
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*
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*> \param[in] SIDE
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*> \verbatim
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*> SIDE is CHARACTER*1
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*> = 'L': apply H or H**T from the Left
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*> = 'R': apply H or H**T from the Right
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*> \endverbatim
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*>
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*> \param[in] TRANS
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*> \verbatim
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*> TRANS is CHARACTER*1
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*> = 'N': apply H (No transpose)
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*> = 'T': apply H**T (Transpose)
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*> \endverbatim
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*>
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*> \param[in] DIRECT
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*> \verbatim
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*> DIRECT is CHARACTER*1
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*> Indicates how H is formed from a product of elementary
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*> reflectors
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*> = 'F': H = H(1) H(2) . . . H(k) (Forward)
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*> = 'B': H = H(k) . . . H(2) H(1) (Backward)
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*> \endverbatim
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*>
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*> \param[in] STOREV
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*> \verbatim
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*> STOREV is CHARACTER*1
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*> Indicates how the vectors which define the elementary
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*> reflectors are stored:
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*> = 'C': Columnwise
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*> = 'R': Rowwise
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*> \endverbatim
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*>
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*> \param[in] M
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*> \verbatim
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*> M is INTEGER
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*> The number of rows of the matrix C.
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*> \endverbatim
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*>
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*> \param[in] N
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*> \verbatim
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*> N is INTEGER
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*> The number of columns of the matrix C.
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*> \endverbatim
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*>
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*> \param[in] K
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*> \verbatim
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*> K is INTEGER
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*> The order of the matrix T (= the number of elementary
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*> reflectors whose product defines the block reflector).
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*> If SIDE = 'L', M >= K >= 0;
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*> if SIDE = 'R', N >= K >= 0.
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*> \endverbatim
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*>
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*> \param[in] V
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*> \verbatim
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*> V is DOUBLE PRECISION array, dimension
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*> (LDV,K) if STOREV = 'C'
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*> (LDV,M) if STOREV = 'R' and SIDE = 'L'
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*> (LDV,N) if STOREV = 'R' and SIDE = 'R'
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*> The matrix V. See Further Details.
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*> \endverbatim
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*>
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*> \param[in] LDV
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*> \verbatim
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*> LDV is INTEGER
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*> The leading dimension of the array V.
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*> If STOREV = 'C' and SIDE = 'L', LDV >= max(1,M);
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*> if STOREV = 'C' and SIDE = 'R', LDV >= max(1,N);
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*> if STOREV = 'R', LDV >= K.
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*> \endverbatim
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*>
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*> \param[in] T
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*> \verbatim
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*> T is DOUBLE PRECISION array, dimension (LDT,K)
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*> The triangular k by k matrix T in the representation of the
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*> block reflector.
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*> \endverbatim
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*>
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*> \param[in] LDT
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*> \verbatim
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*> LDT is INTEGER
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*> The leading dimension of the array T. LDT >= K.
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*> \endverbatim
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*>
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*> \param[in,out] C
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*> \verbatim
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*> C is DOUBLE PRECISION array, dimension (LDC,N)
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*> On entry, the m by n matrix C.
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*> On exit, C is overwritten by H*C or H**T*C or C*H or C*H**T.
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*> \endverbatim
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*>
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*> \param[in] LDC
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*> \verbatim
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*> LDC is INTEGER
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*> The leading dimension of the array C. LDC >= max(1,M).
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*> \endverbatim
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*>
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*> \param[out] WORK
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*> \verbatim
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*> WORK is DOUBLE PRECISION array, dimension (LDWORK,K)
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*> \endverbatim
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*>
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*> \param[in] LDWORK
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*> \verbatim
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*> LDWORK is INTEGER
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*> The leading dimension of the array WORK.
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*> If SIDE = 'L', LDWORK >= max(1,N);
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*> if SIDE = 'R', LDWORK >= max(1,M).
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*> \endverbatim
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*
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* Authors:
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* ========
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*
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*> \author Univ. of Tennessee
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*> \author Univ. of California Berkeley
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*> \author Univ. of Colorado Denver
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*> \author NAG Ltd.
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*
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*> \ingroup doubleOTHERauxiliary
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*
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*> \par Further Details:
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* =====================
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*>
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*> \verbatim
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*>
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*> The shape of the matrix V and the storage of the vectors which define
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*> the H(i) is best illustrated by the following example with n = 5 and
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*> k = 3. The elements equal to 1 are not stored; the corresponding
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*> array elements are modified but restored on exit. The rest of the
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*> array is not used.
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*>
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*> DIRECT = 'F' and STOREV = 'C': DIRECT = 'F' and STOREV = 'R':
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*>
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*> V = ( 1 ) V = ( 1 v1 v1 v1 v1 )
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*> ( v1 1 ) ( 1 v2 v2 v2 )
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*> ( v1 v2 1 ) ( 1 v3 v3 )
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*> ( v1 v2 v3 )
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*> ( v1 v2 v3 )
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*>
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*> DIRECT = 'B' and STOREV = 'C': DIRECT = 'B' and STOREV = 'R':
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*>
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*> V = ( v1 v2 v3 ) V = ( v1 v1 1 )
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*> ( v1 v2 v3 ) ( v2 v2 v2 1 )
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*> ( 1 v2 v3 ) ( v3 v3 v3 v3 1 )
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*> ( 1 v3 )
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*> ( 1 )
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*> \endverbatim
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*>
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* =====================================================================
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SUBROUTINE DLARFB( SIDE, TRANS, DIRECT, STOREV, M, N, K, V, LDV,
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$ T, LDT, C, LDC, WORK, LDWORK )
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*
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* -- LAPACK auxiliary routine --
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* -- LAPACK is a software package provided by Univ. of Tennessee, --
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* -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
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*
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* .. Scalar Arguments ..
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CHARACTER DIRECT, SIDE, STOREV, TRANS
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INTEGER K, LDC, LDT, LDV, LDWORK, M, N
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* ..
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* .. Array Arguments ..
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DOUBLE PRECISION C( LDC, * ), T( LDT, * ), V( LDV, * ),
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$ WORK( LDWORK, * )
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* ..
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*
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* =====================================================================
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*
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* .. Parameters ..
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DOUBLE PRECISION ONE
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PARAMETER ( ONE = 1.0D+0 )
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* ..
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* .. Local Scalars ..
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CHARACTER TRANST
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INTEGER I, J
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* ..
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* .. External Functions ..
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LOGICAL LSAME
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EXTERNAL LSAME
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* ..
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* .. External Subroutines ..
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EXTERNAL DCOPY, DGEMM, DTRMM
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* ..
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* .. Executable Statements ..
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*
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* Quick return if possible
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*
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IF( M.LE.0 .OR. N.LE.0 )
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$ RETURN
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*
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IF( LSAME( TRANS, 'N' ) ) THEN
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TRANST = 'T'
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ELSE
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TRANST = 'N'
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END IF
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*
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IF( LSAME( STOREV, 'C' ) ) THEN
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*
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IF( LSAME( DIRECT, 'F' ) ) THEN
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*
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* Let V = ( V1 ) (first K rows)
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* ( V2 )
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* where V1 is unit lower triangular.
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*
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IF( LSAME( SIDE, 'L' ) ) THEN
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*
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* Form H * C or H**T * C where C = ( C1 )
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* ( C2 )
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*
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* W := C**T * V = (C1**T * V1 + C2**T * V2) (stored in WORK)
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*
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* W := C1**T
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*
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DO 10 J = 1, K
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CALL DCOPY( N, C( J, 1 ), LDC, WORK( 1, J ), 1 )
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10 CONTINUE
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*
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* W := W * V1
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*
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CALL DTRMM( 'Right', 'Lower', 'No transpose', 'Unit', N,
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$ K, ONE, V, LDV, WORK, LDWORK )
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IF( M.GT.K ) THEN
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*
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* W := W + C2**T * V2
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*
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CALL DGEMM( 'Transpose', 'No transpose', N, K, M-K,
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$ ONE, C( K+1, 1 ), LDC, V( K+1, 1 ), LDV,
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$ ONE, WORK, LDWORK )
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END IF
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*
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* W := W * T**T or W * T
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*
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CALL DTRMM( 'Right', 'Upper', TRANST, 'Non-unit', N, K,
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$ ONE, T, LDT, WORK, LDWORK )
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*
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* C := C - V * W**T
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*
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IF( M.GT.K ) THEN
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*
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* C2 := C2 - V2 * W**T
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*
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CALL DGEMM( 'No transpose', 'Transpose', M-K, N, K,
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$ -ONE, V( K+1, 1 ), LDV, WORK, LDWORK, ONE,
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$ C( K+1, 1 ), LDC )
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END IF
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*
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* W := W * V1**T
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*
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CALL DTRMM( 'Right', 'Lower', 'Transpose', 'Unit', N, K,
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$ ONE, V, LDV, WORK, LDWORK )
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*
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* C1 := C1 - W**T
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*
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DO 30 J = 1, K
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DO 20 I = 1, N
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C( J, I ) = C( J, I ) - WORK( I, J )
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20 CONTINUE
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30 CONTINUE
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*
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ELSE IF( LSAME( SIDE, 'R' ) ) THEN
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*
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* Form C * H or C * H**T where C = ( C1 C2 )
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*
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* W := C * V = (C1*V1 + C2*V2) (stored in WORK)
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*
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* W := C1
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*
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DO 40 J = 1, K
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CALL DCOPY( M, C( 1, J ), 1, WORK( 1, J ), 1 )
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40 CONTINUE
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*
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* W := W * V1
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*
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CALL DTRMM( 'Right', 'Lower', 'No transpose', 'Unit', M,
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$ K, ONE, V, LDV, WORK, LDWORK )
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IF( N.GT.K ) THEN
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*
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* W := W + C2 * V2
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*
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CALL DGEMM( 'No transpose', 'No transpose', M, K, N-K,
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$ ONE, C( 1, K+1 ), LDC, V( K+1, 1 ), LDV,
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$ ONE, WORK, LDWORK )
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END IF
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*
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* W := W * T or W * T**T
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*
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CALL DTRMM( 'Right', 'Upper', TRANS, 'Non-unit', M, K,
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$ ONE, T, LDT, WORK, LDWORK )
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*
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* C := C - W * V**T
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*
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IF( N.GT.K ) THEN
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*
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* C2 := C2 - W * V2**T
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*
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CALL DGEMM( 'No transpose', 'Transpose', M, N-K, K,
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$ -ONE, WORK, LDWORK, V( K+1, 1 ), LDV, ONE,
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$ C( 1, K+1 ), LDC )
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END IF
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*
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* W := W * V1**T
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*
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CALL DTRMM( 'Right', 'Lower', 'Transpose', 'Unit', M, K,
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$ ONE, V, LDV, WORK, LDWORK )
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*
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* C1 := C1 - W
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*
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DO 60 J = 1, K
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DO 50 I = 1, M
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C( I, J ) = C( I, J ) - WORK( I, J )
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50 CONTINUE
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60 CONTINUE
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END IF
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*
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ELSE
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*
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* Let V = ( V1 )
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* ( V2 ) (last K rows)
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* where V2 is unit upper triangular.
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*
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IF( LSAME( SIDE, 'L' ) ) THEN
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*
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* Form H * C or H**T * C where C = ( C1 )
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* ( C2 )
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*
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* W := C**T * V = (C1**T * V1 + C2**T * V2) (stored in WORK)
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*
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* W := C2**T
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*
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DO 70 J = 1, K
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CALL DCOPY( N, C( M-K+J, 1 ), LDC, WORK( 1, J ), 1 )
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70 CONTINUE
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*
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* W := W * V2
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*
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CALL DTRMM( 'Right', 'Upper', 'No transpose', 'Unit', N,
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$ K, ONE, V( M-K+1, 1 ), LDV, WORK, LDWORK )
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IF( M.GT.K ) THEN
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*
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* W := W + C1**T * V1
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*
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CALL DGEMM( 'Transpose', 'No transpose', N, K, M-K,
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$ ONE, C, LDC, V, LDV, ONE, WORK, LDWORK )
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END IF
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*
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* W := W * T**T or W * T
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*
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CALL DTRMM( 'Right', 'Lower', TRANST, 'Non-unit', N, K,
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$ ONE, T, LDT, WORK, LDWORK )
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*
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* C := C - V * W**T
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*
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IF( M.GT.K ) THEN
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*
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* C1 := C1 - V1 * W**T
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*
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CALL DGEMM( 'No transpose', 'Transpose', M-K, N, K,
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$ -ONE, V, LDV, WORK, LDWORK, ONE, C, LDC )
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END IF
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*
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* W := W * V2**T
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*
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CALL DTRMM( 'Right', 'Upper', 'Transpose', 'Unit', N, K,
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$ ONE, V( M-K+1, 1 ), LDV, WORK, LDWORK )
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*
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* C2 := C2 - W**T
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*
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DO 90 J = 1, K
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DO 80 I = 1, N
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C( M-K+J, I ) = C( M-K+J, I ) - WORK( I, J )
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80 CONTINUE
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90 CONTINUE
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*
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ELSE IF( LSAME( SIDE, 'R' ) ) THEN
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*
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* Form C * H or C * H**T where C = ( C1 C2 )
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*
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* W := C * V = (C1*V1 + C2*V2) (stored in WORK)
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*
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* W := C2
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*
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DO 100 J = 1, K
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CALL DCOPY( M, C( 1, N-K+J ), 1, WORK( 1, J ), 1 )
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100 CONTINUE
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*
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* W := W * V2
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*
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CALL DTRMM( 'Right', 'Upper', 'No transpose', 'Unit', M,
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$ K, ONE, V( N-K+1, 1 ), LDV, WORK, LDWORK )
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IF( N.GT.K ) THEN
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*
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* W := W + C1 * V1
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*
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CALL DGEMM( 'No transpose', 'No transpose', M, K, N-K,
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$ ONE, C, LDC, V, LDV, ONE, WORK, LDWORK )
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END IF
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*
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* W := W * T or W * T**T
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*
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CALL DTRMM( 'Right', 'Lower', TRANS, 'Non-unit', M, K,
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$ ONE, T, LDT, WORK, LDWORK )
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*
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* C := C - W * V**T
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*
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IF( N.GT.K ) THEN
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*
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* C1 := C1 - W * V1**T
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*
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CALL DGEMM( 'No transpose', 'Transpose', M, N-K, K,
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$ -ONE, WORK, LDWORK, V, LDV, ONE, C, LDC )
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END IF
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*
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* W := W * V2**T
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*
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CALL DTRMM( 'Right', 'Upper', 'Transpose', 'Unit', M, K,
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$ ONE, V( N-K+1, 1 ), LDV, WORK, LDWORK )
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*
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* C2 := C2 - W
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*
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DO 120 J = 1, K
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DO 110 I = 1, M
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C( I, N-K+J ) = C( I, N-K+J ) - WORK( I, J )
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110 CONTINUE
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120 CONTINUE
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END IF
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END IF
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*
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ELSE IF( LSAME( STOREV, 'R' ) ) THEN
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*
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IF( LSAME( DIRECT, 'F' ) ) THEN
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*
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* Let V = ( V1 V2 ) (V1: first K columns)
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* where V1 is unit upper triangular.
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*
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IF( LSAME( SIDE, 'L' ) ) THEN
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*
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* Form H * C or H**T * C where C = ( C1 )
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* ( C2 )
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*
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* W := C**T * V**T = (C1**T * V1**T + C2**T * V2**T) (stored in WORK)
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*
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* W := C1**T
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*
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DO 130 J = 1, K
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CALL DCOPY( N, C( J, 1 ), LDC, WORK( 1, J ), 1 )
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130 CONTINUE
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*
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* W := W * V1**T
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*
|
|
CALL DTRMM( 'Right', 'Upper', 'Transpose', 'Unit', N, K,
|
|
$ ONE, V, LDV, WORK, LDWORK )
|
|
IF( M.GT.K ) THEN
|
|
*
|
|
* W := W + C2**T * V2**T
|
|
*
|
|
CALL DGEMM( 'Transpose', 'Transpose', N, K, M-K, ONE,
|
|
$ C( K+1, 1 ), LDC, V( 1, K+1 ), LDV, ONE,
|
|
$ WORK, LDWORK )
|
|
END IF
|
|
*
|
|
* W := W * T**T or W * T
|
|
*
|
|
CALL DTRMM( 'Right', 'Upper', TRANST, 'Non-unit', N, K,
|
|
$ ONE, T, LDT, WORK, LDWORK )
|
|
*
|
|
* C := C - V**T * W**T
|
|
*
|
|
IF( M.GT.K ) THEN
|
|
*
|
|
* C2 := C2 - V2**T * W**T
|
|
*
|
|
CALL DGEMM( 'Transpose', 'Transpose', M-K, N, K, -ONE,
|
|
$ V( 1, K+1 ), LDV, WORK, LDWORK, ONE,
|
|
$ C( K+1, 1 ), LDC )
|
|
END IF
|
|
*
|
|
* W := W * V1
|
|
*
|
|
CALL DTRMM( 'Right', 'Upper', 'No transpose', 'Unit', N,
|
|
$ K, ONE, V, LDV, WORK, LDWORK )
|
|
*
|
|
* C1 := C1 - W**T
|
|
*
|
|
DO 150 J = 1, K
|
|
DO 140 I = 1, N
|
|
C( J, I ) = C( J, I ) - WORK( I, J )
|
|
140 CONTINUE
|
|
150 CONTINUE
|
|
*
|
|
ELSE IF( LSAME( SIDE, 'R' ) ) THEN
|
|
*
|
|
* Form C * H or C * H**T where C = ( C1 C2 )
|
|
*
|
|
* W := C * V**T = (C1*V1**T + C2*V2**T) (stored in WORK)
|
|
*
|
|
* W := C1
|
|
*
|
|
DO 160 J = 1, K
|
|
CALL DCOPY( M, C( 1, J ), 1, WORK( 1, J ), 1 )
|
|
160 CONTINUE
|
|
*
|
|
* W := W * V1**T
|
|
*
|
|
CALL DTRMM( 'Right', 'Upper', 'Transpose', 'Unit', M, K,
|
|
$ ONE, V, LDV, WORK, LDWORK )
|
|
IF( N.GT.K ) THEN
|
|
*
|
|
* W := W + C2 * V2**T
|
|
*
|
|
CALL DGEMM( 'No transpose', 'Transpose', M, K, N-K,
|
|
$ ONE, C( 1, K+1 ), LDC, V( 1, K+1 ), LDV,
|
|
$ ONE, WORK, LDWORK )
|
|
END IF
|
|
*
|
|
* W := W * T or W * T**T
|
|
*
|
|
CALL DTRMM( 'Right', 'Upper', TRANS, 'Non-unit', M, K,
|
|
$ ONE, T, LDT, WORK, LDWORK )
|
|
*
|
|
* C := C - W * V
|
|
*
|
|
IF( N.GT.K ) THEN
|
|
*
|
|
* C2 := C2 - W * V2
|
|
*
|
|
CALL DGEMM( 'No transpose', 'No transpose', M, N-K, K,
|
|
$ -ONE, WORK, LDWORK, V( 1, K+1 ), LDV, ONE,
|
|
$ C( 1, K+1 ), LDC )
|
|
END IF
|
|
*
|
|
* W := W * V1
|
|
*
|
|
CALL DTRMM( 'Right', 'Upper', 'No transpose', 'Unit', M,
|
|
$ K, ONE, V, LDV, WORK, LDWORK )
|
|
*
|
|
* C1 := C1 - W
|
|
*
|
|
DO 180 J = 1, K
|
|
DO 170 I = 1, M
|
|
C( I, J ) = C( I, J ) - WORK( I, J )
|
|
170 CONTINUE
|
|
180 CONTINUE
|
|
*
|
|
END IF
|
|
*
|
|
ELSE
|
|
*
|
|
* Let V = ( V1 V2 ) (V2: last K columns)
|
|
* where V2 is unit lower triangular.
|
|
*
|
|
IF( LSAME( SIDE, 'L' ) ) THEN
|
|
*
|
|
* Form H * C or H**T * C where C = ( C1 )
|
|
* ( C2 )
|
|
*
|
|
* W := C**T * V**T = (C1**T * V1**T + C2**T * V2**T) (stored in WORK)
|
|
*
|
|
* W := C2**T
|
|
*
|
|
DO 190 J = 1, K
|
|
CALL DCOPY( N, C( M-K+J, 1 ), LDC, WORK( 1, J ), 1 )
|
|
190 CONTINUE
|
|
*
|
|
* W := W * V2**T
|
|
*
|
|
CALL DTRMM( 'Right', 'Lower', 'Transpose', 'Unit', N, K,
|
|
$ ONE, V( 1, M-K+1 ), LDV, WORK, LDWORK )
|
|
IF( M.GT.K ) THEN
|
|
*
|
|
* W := W + C1**T * V1**T
|
|
*
|
|
CALL DGEMM( 'Transpose', 'Transpose', N, K, M-K, ONE,
|
|
$ C, LDC, V, LDV, ONE, WORK, LDWORK )
|
|
END IF
|
|
*
|
|
* W := W * T**T or W * T
|
|
*
|
|
CALL DTRMM( 'Right', 'Lower', TRANST, 'Non-unit', N, K,
|
|
$ ONE, T, LDT, WORK, LDWORK )
|
|
*
|
|
* C := C - V**T * W**T
|
|
*
|
|
IF( M.GT.K ) THEN
|
|
*
|
|
* C1 := C1 - V1**T * W**T
|
|
*
|
|
CALL DGEMM( 'Transpose', 'Transpose', M-K, N, K, -ONE,
|
|
$ V, LDV, WORK, LDWORK, ONE, C, LDC )
|
|
END IF
|
|
*
|
|
* W := W * V2
|
|
*
|
|
CALL DTRMM( 'Right', 'Lower', 'No transpose', 'Unit', N,
|
|
$ K, ONE, V( 1, M-K+1 ), LDV, WORK, LDWORK )
|
|
*
|
|
* C2 := C2 - W**T
|
|
*
|
|
DO 210 J = 1, K
|
|
DO 200 I = 1, N
|
|
C( M-K+J, I ) = C( M-K+J, I ) - WORK( I, J )
|
|
200 CONTINUE
|
|
210 CONTINUE
|
|
*
|
|
ELSE IF( LSAME( SIDE, 'R' ) ) THEN
|
|
*
|
|
* Form C * H or C * H' where C = ( C1 C2 )
|
|
*
|
|
* W := C * V**T = (C1*V1**T + C2*V2**T) (stored in WORK)
|
|
*
|
|
* W := C2
|
|
*
|
|
DO 220 J = 1, K
|
|
CALL DCOPY( M, C( 1, N-K+J ), 1, WORK( 1, J ), 1 )
|
|
220 CONTINUE
|
|
*
|
|
* W := W * V2**T
|
|
*
|
|
CALL DTRMM( 'Right', 'Lower', 'Transpose', 'Unit', M, K,
|
|
$ ONE, V( 1, N-K+1 ), LDV, WORK, LDWORK )
|
|
IF( N.GT.K ) THEN
|
|
*
|
|
* W := W + C1 * V1**T
|
|
*
|
|
CALL DGEMM( 'No transpose', 'Transpose', M, K, N-K,
|
|
$ ONE, C, LDC, V, LDV, ONE, WORK, LDWORK )
|
|
END IF
|
|
*
|
|
* W := W * T or W * T**T
|
|
*
|
|
CALL DTRMM( 'Right', 'Lower', TRANS, 'Non-unit', M, K,
|
|
$ ONE, T, LDT, WORK, LDWORK )
|
|
*
|
|
* C := C - W * V
|
|
*
|
|
IF( N.GT.K ) THEN
|
|
*
|
|
* C1 := C1 - W * V1
|
|
*
|
|
CALL DGEMM( 'No transpose', 'No transpose', M, N-K, K,
|
|
$ -ONE, WORK, LDWORK, V, LDV, ONE, C, LDC )
|
|
END IF
|
|
*
|
|
* W := W * V2
|
|
*
|
|
CALL DTRMM( 'Right', 'Lower', 'No transpose', 'Unit', M,
|
|
$ K, ONE, V( 1, N-K+1 ), LDV, WORK, LDWORK )
|
|
*
|
|
* C1 := C1 - W
|
|
*
|
|
DO 240 J = 1, K
|
|
DO 230 I = 1, M
|
|
C( I, N-K+J ) = C( I, N-K+J ) - WORK( I, J )
|
|
230 CONTINUE
|
|
240 CONTINUE
|
|
*
|
|
END IF
|
|
*
|
|
END IF
|
|
END IF
|
|
*
|
|
RETURN
|
|
*
|
|
* End of DLARFB
|
|
*
|
|
END
|