dorg2r()

subroutine dorg2r	(	integer	m,
		integer	n,
		integer	k,
		double precision, dimension( lda, * )	a,
		integer	lda,
		double precision, dimension( * )	tau,
		double precision, dimension( * )	work,
		integer	info )

DORG2R generates all or part of the orthogonal matrix Q from a QR factorization determined by sgeqrf (unblocked algorithm).

Download DORG2R + dependencies [TGZ] [ZIP] [TXT]

Purpose:

!>
!> DORG2R generates an m by n real matrix Q with orthonormal columns,
!> which is defined as the first n columns of a product of k elementary
!> reflectors of order m
!>
!>       Q  =  H(1) H(2) . . . H(k)
!>
!> as returned by DGEQRF.
!> 

Parameters

[in]	M	!> M is INTEGER !> The number of rows of the matrix Q. M >= 0. !>
[in]	N	!> N is INTEGER !> The number of columns of the matrix Q. M >= N >= 0. !>
[in]	K	!> K is INTEGER !> The number of elementary reflectors whose product defines the !> matrix Q. N >= K >= 0. !>
[in,out]	A	!> A is DOUBLE PRECISION array, dimension (LDA,N) !> On entry, the i-th column must contain the vector which !> defines the elementary reflector H(i), for i = 1,2,...,k, as !> returned by DGEQRF in the first k columns of its array !> argument A. !> On exit, the m-by-n matrix Q. !>
[in]	LDA	!> LDA is INTEGER !> The first dimension of the array A. LDA >= max(1,M). !>
[in]	TAU	!> TAU is DOUBLE PRECISION array, dimension (K) !> TAU(i) must contain the scalar factor of the elementary !> reflector H(i), as returned by DGEQRF. !>
[out]	WORK	!> WORK is DOUBLE PRECISION array, dimension (N) !>
[out]	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.