dorg2l(3)

dorg2l3

Part of dorg2l.f(3).

Usage

Functions/Subroutines

subroutine dorg2l (m, n, k, a, lda, tau, work, info)
DORG2L generates all or part of the orthogonal matrix Q from a QL factorization determined by sgeqlf (unblocked algorithm).

Function/Subroutine Documentation

subroutine dorg2l (integer m, integer n, integer k, double precision, dimension( lda, * ) a, integer lda, double precision, dimension( * ) tau, double precision, dimension( * ) work, integer info)

DORG2L generates all or part of the orthogonal matrix Q from a QL factorization determined by sgeqlf (unblocked algorithm).

Purpose:

!>
!> DORG2L generates an m by n real matrix Q with orthonormal columns,
!> which is defined as the last n columns of a product of k elementary
!> reflectors of order m
!>
!>       Q  =  H(k) . . . H(2) H(1)
!>
!> as returned by DGEQLF.
!> 

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. M >= N >= 0.
!> 

K

!>          K is INTEGER
!>          The number of elementary reflectors whose product defines the
!>          matrix Q. N >= K >= 0.
!> 

A

!>          A is DOUBLE PRECISION array, dimension (LDA,N)
!>          On entry, the (n-k+i)-th column must contain the vector which
!>          defines the elementary reflector H(i), for i = 1,2,...,k, as
!>          returned by DGEQLF in the last k columns 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 DGEQLF.
!> 

WORK

!>          WORK is DOUBLE PRECISION array, dimension (N)
!> 

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 113 of file dorg2l.f.

Releases

14 releases since Debian 1.3 (Bo); the text changed 10 times.

  1. 1.3
  2. 2.0–2.2
  3. 3.0
  4. 3.1–4.0
  5. 7
  6. 8
  7. 9
  8. 10
  9. 11
  10. 12
  11. Arch

Author

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