table of contents
/home/abuild/rpmbuild/BUILD/lapack-3.12.0/SRC/dorgrq.f(3) | Library Functions Manual | /home/abuild/rpmbuild/BUILD/lapack-3.12.0/SRC/dorgrq.f(3) |
NAME¶
/home/abuild/rpmbuild/BUILD/lapack-3.12.0/SRC/dorgrq.f
SYNOPSIS¶
Functions/Subroutines¶
subroutine DORGRQ (m, n, k, a, lda, tau, work, lwork, info)
DORGRQ
Function/Subroutine Documentation¶
subroutine DORGRQ (integer m, integer n, integer k, double precision, dimension( lda, * ) a, integer lda, double precision, dimension( * ) tau, double precision, dimension( * ) work, integer lwork, integer info)¶
DORGRQ
Purpose:
!> !> DORGRQ generates an M-by-N real matrix Q with orthonormal rows, !> which is defined as the last M rows of a product of K elementary !> reflectors of order N !> !> Q = H(1) H(2) . . . H(k) !> !> as returned by DGERQF. !>
Parameters
M
!> M is INTEGER !> The number of rows of the matrix Q. M >= 0. !>
N
!> N is INTEGER !> The number of columns of the matrix Q. N >= M. !>
K
!> K is INTEGER !> The number of elementary reflectors whose product defines the !> matrix Q. M >= K >= 0. !>
A
!> A is DOUBLE PRECISION array, dimension (LDA,N) !> On entry, the (m-k+i)-th row must contain the vector which !> defines the elementary reflector H(i), for i = 1,2,...,k, as !> returned by DGERQF in the last k rows of its array argument !> A. !> On exit, the M-by-N matrix Q. !>
LDA
!> LDA is INTEGER !> The first dimension of the array A. LDA >= max(1,M). !>
TAU
!> TAU is DOUBLE PRECISION array, dimension (K) !> TAU(i) must contain the scalar factor of the elementary !> reflector H(i), as returned by DGERQF. !>
WORK
!> WORK is DOUBLE PRECISION array, dimension (MAX(1,LWORK)) !> On exit, if INFO = 0, WORK(1) returns the optimal LWORK. !>
LWORK
!> LWORK is INTEGER !> The dimension of the array WORK. LWORK >= max(1,M). !> For optimum performance LWORK >= M*NB, where NB is the !> optimal blocksize. !> !> If LWORK = -1, then a workspace query is assumed; the routine !> only calculates the optimal size of the WORK array, returns !> this value as the first entry of the WORK array, and no error !> message related to LWORK is issued by XERBLA. !>
INFO
!> INFO is INTEGER !> = 0: successful exit !> < 0: if INFO = -i, the i-th argument has an illegal value !>
Author
Univ. of Tennessee
Univ. of California Berkeley
Univ. of Colorado Denver
NAG Ltd.
Definition at line 127 of file dorgrq.f.
Author¶
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Version 3.12.0 | LAPACK |