sgemlq.f - Man Page
SRC/sgemlq.f
Synopsis
Functions/Subroutines
subroutine sgemlq (side, trans, m, n, k, a, lda, t, tsize, c, ldc, work, lwork, info)
SGEMLQ
Function/Subroutine Documentation
subroutine sgemlq (character side, character trans, integer m, integer n, integer k, real, dimension( lda, * ) a, integer lda, real, dimension( * ) t, integer tsize, real, dimension( ldc, * ) c, integer ldc, real, dimension( * ) work, integer lwork, integer info)
SGEMLQ
Purpose:
SGEMLQ 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 real orthogonal matrix defined as the product of blocked elementary reflectors computed by short wide LQ factorization (SGELQ)
- Parameters
SIDE
SIDE is CHARACTER*1 = 'L': apply Q or Q**T from the Left; = 'R': apply Q or Q**T from the Right.
TRANS
TRANS is CHARACTER*1 = 'N': No transpose, apply Q; = 'T': Transpose, apply Q**T.
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 REAL array, dimension (LDA,M) if SIDE = 'L', (LDA,N) if SIDE = 'R' Part of the data structure to represent Q as returned by DGELQ.
LDA
LDA is INTEGER The leading dimension of the array A. LDA >= max(1,K).
T
T is REAL array, dimension (MAX(5,TSIZE)). Part of the data structure to represent Q as returned by SGELQ.
TSIZE
TSIZE is INTEGER The dimension of the array T. TSIZE >= 5.
C
C is REAL 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.
LDC
LDC is INTEGER The leading dimension of the array C. LDC >= max(1,M).
WORK
(workspace) REAL 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 SLASWLQ or SGELQT Depending on the matrix dimensions M and N, and row and column block sizes MB and NB returned by ILAENV, SGELQ will use either SLASWLQ (if the matrix is wide-and-short) or SGELQT to compute the LQ factorization. This version of SGEMLQ will use either SLAMSWLQ or SGEMLQT to multiply matrix Q by another matrix. Further Details in SLAMSWLQ or SGEMLQT.
Definition at line 170 of file sgemlq.f.
Author
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Referenced By
The man page sgemlq(3) is an alias of sgemlq.f(3).
Tue Nov 28 2023 12:08:42 Version 3.12.0 LAPACK