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381 lines
10 KiB
381 lines
10 KiB
2 years ago
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*> \brief \b CUNMRZ
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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 CUNMRZ + dependencies
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*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.tgz?format=tgz&filename=/lapack/lapack_routine/cunmrz.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/cunmrz.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/cunmrz.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 CUNMRZ( SIDE, TRANS, M, N, K, L, A, LDA, TAU, C, LDC,
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* WORK, LWORK, INFO )
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*
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* .. Scalar Arguments ..
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* CHARACTER SIDE, TRANS
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* INTEGER INFO, K, L, LDA, LDC, LWORK, M, N
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* ..
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* .. Array Arguments ..
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* COMPLEX A( LDA, * ), C( LDC, * ), TAU( * ), WORK( * )
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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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*> CUNMRZ overwrites the general complex M-by-N matrix C with
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*>
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*> SIDE = 'L' SIDE = 'R'
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*> TRANS = 'N': Q * C C * Q
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*> TRANS = 'C': Q**H * C C * Q**H
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*>
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*> where Q is a complex unitary matrix defined as the product of k
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*> elementary reflectors
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*>
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*> Q = H(1) H(2) . . . H(k)
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*>
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*> as returned by CTZRZF. Q is of order M if SIDE = 'L' and of order N
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*> if SIDE = 'R'.
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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 Q or Q**H from the Left;
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*> = 'R': apply Q or Q**H 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': No transpose, apply Q;
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*> = 'C': Conjugate transpose, apply Q**H.
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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. M >= 0.
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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. N >= 0.
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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 number of elementary reflectors whose product defines
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*> the matrix Q.
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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] L
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*> \verbatim
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*> L is INTEGER
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*> The number of columns of the matrix A containing
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*> the meaningful part of the Householder reflectors.
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*> If SIDE = 'L', M >= L >= 0, if SIDE = 'R', N >= L >= 0.
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*> \endverbatim
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*>
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*> \param[in] A
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*> \verbatim
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*> A is COMPLEX array, dimension
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*> (LDA,M) if SIDE = 'L',
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*> (LDA,N) if SIDE = 'R'
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*> The i-th row must contain the vector which defines the
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*> elementary reflector H(i), for i = 1,2,...,k, as returned by
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*> CTZRZF in the last k rows of its array argument A.
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*> A is modified by the routine but restored on exit.
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*> \endverbatim
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*>
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*> \param[in] LDA
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*> \verbatim
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*> LDA is INTEGER
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*> The leading dimension of the array A. LDA >= max(1,K).
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*> \endverbatim
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*>
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*> \param[in] TAU
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*> \verbatim
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*> TAU is COMPLEX array, dimension (K)
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*> TAU(i) must contain the scalar factor of the elementary
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*> reflector H(i), as returned by CTZRZF.
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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 COMPLEX 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 Q*C or Q**H*C or C*Q**H or C*Q.
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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 COMPLEX array, dimension (MAX(1,LWORK))
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*> On exit, if INFO = 0, WORK(1) returns the optimal LWORK.
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*> \endverbatim
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*>
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*> \param[in] LWORK
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*> \verbatim
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*> LWORK is INTEGER
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*> The dimension of the array WORK.
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*> If SIDE = 'L', LWORK >= max(1,N);
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*> if SIDE = 'R', LWORK >= max(1,M).
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*> For good performance, LWORK should generally be larger.
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*>
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*> If LWORK = -1, then a workspace query is assumed; the routine
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*> only calculates the optimal size of the WORK array, returns
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*> this value as the first entry of the WORK array, and no error
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*> message related to LWORK is issued by XERBLA.
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*> \endverbatim
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*>
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*> \param[out] INFO
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*> \verbatim
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*> INFO is INTEGER
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*> = 0: successful exit
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*> < 0: if INFO = -i, the i-th argument had an illegal value
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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 complexOTHERcomputational
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*
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*> \par Contributors:
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* ==================
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*>
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*> A. Petitet, Computer Science Dept., Univ. of Tenn., Knoxville, USA
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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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*> \endverbatim
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*>
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* =====================================================================
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SUBROUTINE CUNMRZ( SIDE, TRANS, M, N, K, L, A, LDA, TAU, C, LDC,
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$ WORK, LWORK, INFO )
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*
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* -- LAPACK computational 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 SIDE, TRANS
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INTEGER INFO, K, L, LDA, LDC, LWORK, M, N
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* ..
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* .. Array Arguments ..
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COMPLEX A( LDA, * ), C( LDC, * ), TAU( * ), WORK( * )
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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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INTEGER NBMAX, LDT, TSIZE
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PARAMETER ( NBMAX = 64, LDT = NBMAX+1,
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$ TSIZE = LDT*NBMAX )
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* ..
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* .. Local Scalars ..
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LOGICAL LEFT, LQUERY, NOTRAN
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CHARACTER TRANST
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INTEGER I, I1, I2, I3, IB, IC, IINFO, IWT, JA, JC,
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$ LDWORK, LWKOPT, MI, NB, NBMIN, NI, NQ, NW
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* ..
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* .. External Functions ..
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LOGICAL LSAME
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INTEGER ILAENV
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EXTERNAL LSAME, ILAENV
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* ..
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* .. External Subroutines ..
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EXTERNAL CLARZB, CLARZT, CUNMR3, XERBLA
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* ..
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* .. Intrinsic Functions ..
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INTRINSIC MAX, MIN
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* ..
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* .. Executable Statements ..
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*
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* Test the input arguments
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*
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INFO = 0
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LEFT = LSAME( SIDE, 'L' )
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NOTRAN = LSAME( TRANS, 'N' )
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LQUERY = ( LWORK.EQ.-1 )
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*
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* NQ is the order of Q and NW is the minimum dimension of WORK
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*
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IF( LEFT ) THEN
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NQ = M
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NW = MAX( 1, N )
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ELSE
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NQ = N
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NW = MAX( 1, M )
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END IF
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IF( .NOT.LEFT .AND. .NOT.LSAME( SIDE, 'R' ) ) THEN
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INFO = -1
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ELSE IF( .NOT.NOTRAN .AND. .NOT.LSAME( TRANS, 'C' ) ) THEN
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INFO = -2
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ELSE IF( M.LT.0 ) THEN
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INFO = -3
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ELSE IF( N.LT.0 ) THEN
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INFO = -4
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ELSE IF( K.LT.0 .OR. K.GT.NQ ) THEN
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INFO = -5
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ELSE IF( L.LT.0 .OR. ( LEFT .AND. ( L.GT.M ) ) .OR.
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$ ( .NOT.LEFT .AND. ( L.GT.N ) ) ) THEN
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INFO = -6
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ELSE IF( LDA.LT.MAX( 1, K ) ) THEN
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INFO = -8
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ELSE IF( LDC.LT.MAX( 1, M ) ) THEN
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INFO = -11
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ELSE IF( LWORK.LT.NW .AND. .NOT.LQUERY ) THEN
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INFO = -13
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END IF
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*
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IF( INFO.EQ.0 ) THEN
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*
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* Compute the workspace requirements
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*
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IF( M.EQ.0 .OR. N.EQ.0 ) THEN
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LWKOPT = 1
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ELSE
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NB = MIN( NBMAX, ILAENV( 1, 'CUNMRQ', SIDE // TRANS, M, N,
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$ K, -1 ) )
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LWKOPT = NW*NB + TSIZE
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END IF
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WORK( 1 ) = LWKOPT
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END IF
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*
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IF( INFO.NE.0 ) THEN
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CALL XERBLA( 'CUNMRZ', -INFO )
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RETURN
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ELSE IF( LQUERY ) THEN
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RETURN
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END IF
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*
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* Quick return if possible
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*
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IF( M.EQ.0 .OR. N.EQ.0 ) THEN
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RETURN
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END IF
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*
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* Determine the block size.
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*
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NB = MIN( NBMAX, ILAENV( 1, 'CUNMRQ', SIDE // TRANS, M, N, K,
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$ -1 ) )
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NBMIN = 2
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LDWORK = NW
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IF( NB.GT.1 .AND. NB.LT.K ) THEN
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IF( LWORK.LT.LWKOPT ) THEN
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NB = (LWORK-TSIZE) / LDWORK
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NBMIN = MAX( 2, ILAENV( 2, 'CUNMRQ', SIDE // TRANS, M, N, K,
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$ -1 ) )
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END IF
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END IF
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*
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IF( NB.LT.NBMIN .OR. NB.GE.K ) THEN
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*
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* Use unblocked code
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*
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CALL CUNMR3( SIDE, TRANS, M, N, K, L, A, LDA, TAU, C, LDC,
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$ WORK, IINFO )
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ELSE
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*
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* Use blocked code
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*
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IWT = 1 + NW*NB
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IF( ( LEFT .AND. .NOT.NOTRAN ) .OR.
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$ ( .NOT.LEFT .AND. NOTRAN ) ) THEN
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I1 = 1
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I2 = K
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I3 = NB
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ELSE
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I1 = ( ( K-1 ) / NB )*NB + 1
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I2 = 1
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I3 = -NB
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END IF
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*
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IF( LEFT ) THEN
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NI = N
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JC = 1
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JA = M - L + 1
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ELSE
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MI = M
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IC = 1
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JA = N - L + 1
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END IF
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*
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IF( NOTRAN ) THEN
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TRANST = 'C'
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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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DO 10 I = I1, I2, I3
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IB = MIN( NB, K-I+1 )
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*
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* Form the triangular factor of the block reflector
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* H = H(i+ib-1) . . . H(i+1) H(i)
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*
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CALL CLARZT( 'Backward', 'Rowwise', L, IB, A( I, JA ), LDA,
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$ TAU( I ), WORK( IWT ), LDT )
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*
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IF( LEFT ) THEN
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*
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* H or H**H is applied to C(i:m,1:n)
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*
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MI = M - I + 1
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IC = I
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ELSE
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*
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* H or H**H is applied to C(1:m,i:n)
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*
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NI = N - I + 1
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JC = I
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END IF
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*
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* Apply H or H**H
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*
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CALL CLARZB( SIDE, TRANST, 'Backward', 'Rowwise', MI, NI,
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$ IB, L, A( I, JA ), LDA, WORK( IWT ), LDT,
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$ C( IC, JC ), LDC, WORK, LDWORK )
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10 CONTINUE
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*
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END IF
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*
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WORK( 1 ) = LWKOPT
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*
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RETURN
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*
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* End of CUNMRZ
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*
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END
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