table of contents
/home/abuild/rpmbuild/BUILD/lapack-3.12.0/SRC/sgelqt3.f(3) | Library Functions Manual | /home/abuild/rpmbuild/BUILD/lapack-3.12.0/SRC/sgelqt3.f(3) |
NAME¶
/home/abuild/rpmbuild/BUILD/lapack-3.12.0/SRC/sgelqt3.f
SYNOPSIS¶
Functions/Subroutines¶
recursive subroutine SGELQT3 (m, n, a, lda, t, ldt, info)
SGELQT3
Function/Subroutine Documentation¶
recursive subroutine SGELQT3 (integer m, integer n, real, dimension( lda, * ) a, integer lda, real, dimension( ldt, * ) t, integer ldt, integer info)¶
SGELQT3
Purpose:
!> !> SGELQT3 recursively computes a LQ factorization of a real M-by-N !> matrix A, using the compact WY representation of Q. !> !> Based on the algorithm of Elmroth and Gustavson, !> IBM J. Res. Develop. Vol 44 No. 4 July 2000. !>
Parameters
M
!> M is INTEGER !> The number of rows of the matrix A. M =< N. !>
N
!> N is INTEGER !> The number of columns of the matrix A. N >= 0. !>
A
!> A is REAL array, dimension (LDA,N) !> On entry, the real M-by-N matrix A. On exit, the elements on and !> below the diagonal contain the N-by-N lower triangular matrix L; the !> elements above the diagonal are the rows of V. See below for !> further details. !>
LDA
!> LDA is INTEGER !> The leading dimension of the array A. LDA >= max(1,M). !>
T
!> T is REAL array, dimension (LDT,N) !> The N-by-N upper triangular factor of the block reflector. !> The elements on and above the diagonal contain the block !> reflector T; the elements below the diagonal are not used. !> See below for further details. !>
LDT
!> LDT is INTEGER !> The leading dimension of the array T. LDT >= max(1,N). !>
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:
!> !> The matrix V stores the elementary reflectors H(i) in the i-th row !> above the diagonal. For example, if M=5 and N=3, the matrix V is !> !> V = ( 1 v1 v1 v1 v1 ) !> ( 1 v2 v2 v2 ) !> ( 1 v3 v3 v3 ) !> !> !> where the vi's represent the vectors which define H(i), which are returned !> in the matrix A. The 1's along the diagonal of V are not stored in A. The !> block reflector H is then given by !> !> H = I - V * T * V**T !> !> where V**T is the transpose of V. !> !> For details of the algorithm, see Elmroth and Gustavson (cited above). !>
Definition at line 115 of file sgelqt3.f.
Author¶
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