dgemlqt.f3
Usage
Functions/Subroutines
subroutine dgemlqt (side, trans, m, n, k, mb, v, ldv, t, ldt, c, ldc, work, info)
DGEMLQT
Function/Subroutine Documentation
subroutine dgemlqt (character side, character trans, integer m, integer n, integer k, integer mb, double precision, dimension( ldv, * ) v, integer ldv, double precision, dimension( ldt, * ) t, integer ldt, double precision, dimension( ldc, * ) c, integer ldc, double precision, dimension( * ) work, integer info)
DGEMLQT
Purpose:
!> !> DGEMLQT 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 K !> elementary reflectors: !> !> Q = H(1) H(2) . . . H(K) = I - V T V**T !> !> generated using the compact WY representation as returned by DGELQT. !> !> Q is of order M if SIDE = 'L' and of order N if SIDE = 'R'. !>
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; !> = 'C': Transpose, apply Q**T. !>
M
!> M is INTEGER !> The number of rows of the matrix C. 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. !>
MB
!> MB is INTEGER !> The block size used for the storage of T. K >= MB >= 1. !> This must be the same value of MB used to generate T !> in DGELQT. !>
V
!> V is DOUBLE PRECISION array, dimension !> (LDV,M) if SIDE = 'L', !> (LDV,N) if SIDE = 'R' !> The i-th row must contain the vector which defines the !> elementary reflector H(i), for i = 1,2,...,k, as returned by !> DGELQT in the first K rows of its array argument A. !>
LDV
!> LDV is INTEGER !> The leading dimension of the array V. LDV >= max(1,K). !>
T
!> T is DOUBLE PRECISION array, dimension (LDT,K) !> The upper triangular factors of the block reflectors !> as returned by DGELQT, stored as a MB-by-K matrix. !>
LDT
!> LDT is INTEGER !> The leading dimension of the array T. LDT >= MB. !>
C
!> C is DOUBLE PRECISION array, dimension (LDC,N) !> On entry, the M-by-N matrix C. !> On exit, C is overwritten by Q C, Q**T C, C Q**T or C Q. !>
LDC
!> LDC is INTEGER !> The leading dimension of the array C. LDC >= max(1,M). !>
WORK
!> WORK is DOUBLE PRECISION array. The dimension of !> WORK is N*MB if SIDE = 'L', or M*MB if SIDE = 'R'. !>
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.
Definition at line 166 of file dgemlqt.f.
Releases
2 releases since Debian 9 (Stretch); the text changed 1 time.