SRC/zgemlq.f(3) | Library Functions Manual | SRC/zgemlq.f(3) |
NAME
SRC/zgemlq.f
SYNOPSIS
Functions/Subroutines
subroutine zgemlq (side, trans, m, n, k, a, lda, t, tsize,
c, ldc, work, lwork, info)
ZGEMLQ
Function/Subroutine Documentation
subroutine zgemlq (character side, character trans, integer m, integer n, integer k, complex*16, dimension( lda, * ) a, integer lda, complex*16, dimension( * ) t, integer tsize, complex*16, dimension( ldc, * ) c, integer ldc, complex*16, dimension( * ) work, integer lwork, integer info)
ZGEMLQ
Purpose:
ZGEMLQ overwrites the general real 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 defined as the product of blocked elementary reflectors computed by short wide LQ factorization (ZGELQ)
Parameters
SIDE
SIDE is CHARACTER*1 = 'L': apply Q or Q**H from the Left; = 'R': apply Q or Q**H from the Right.
TRANS
TRANS is CHARACTER*1 = 'N': No transpose, apply Q; = 'C': Conjugate transpose, apply Q**H.
M
M is INTEGER The number of rows of the matrix A. M >=0.
N
N is INTEGER The number of columns of the matrix C. N >= 0.
K
K is INTEGER The number of elementary reflectors whose product defines the matrix Q. If SIDE = 'L', M >= K >= 0; if SIDE = 'R', N >= K >= 0.
A
A is COMPLEX*16 array, dimension (LDA,M) if SIDE = 'L', (LDA,N) if SIDE = 'R' Part of the data structure to represent Q as returned by ZGELQ.
LDA
LDA is INTEGER The leading dimension of the array A. LDA >= max(1,K).
T
T is COMPLEX*16 array, dimension (MAX(5,TSIZE)). Part of the data structure to represent Q as returned by ZGELQ.
TSIZE
TSIZE is INTEGER The dimension of the array T. TSIZE >= 5.
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**H*C or C*Q**H or C*Q.
LDC
LDC is INTEGER The leading dimension of the array C. LDC >= max(1,M).
WORK
(workspace) COMPLEX*16 array, dimension (MAX(1,LWORK))
LWORK
LWORK is INTEGER The dimension of the array WORK. If LWORK = -1, then a workspace query is assumed. The routine only calculates the size of the WORK array, returns this value as WORK(1), and no error message related to WORK is issued by XERBLA.
INFO
INFO is INTEGER = 0: successful exit < 0: if INFO = -i, the i-th argument had an illegal value
Author
Univ. of Tennessee
Univ. of California Berkeley
Univ. of Colorado Denver
NAG Ltd.
Further Details
These details are particular for this LAPACK implementation. Users should not take them for granted. These details may change in the future, and are not likely true for another LAPACK implementation. These details are relevant if one wants to try to understand the code. They are not part of the interface. In this version, T(2): row block size (MB) T(3): column block size (NB) T(6:TSIZE): data structure needed for Q, computed by ZLASWLQ or ZGELQT Depending on the matrix dimensions M and N, and row and column block sizes MB and NB returned by ILAENV, ZGELQ will use either ZLASWLQ (if the matrix is wide-and-short) or ZGELQT to compute the LQ factorization. This version of ZGEMLQ will use either ZLAMSWLQ or ZGEMLQT to multiply matrix Q by another matrix. Further Details in ZLAMSWLQ or ZGEMLQT.
Definition at line 169 of file zgemlq.f.
Author
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