dorg2r.f man page

dorg2r.f —

Synopsis

Functions/Subroutines

subroutine dorg2r (M, N, K, A, LDA, TAU, WORK, INFO)
DORG2R generates all or part of the orthogonal matrix Q from a QR factorization determined by sgeqrf (unblocked algorithm).

Function/Subroutine Documentation

subroutine dorg2r (integerM, integerN, integerK, double precision, dimension( lda, * )A, integerLDA, double precision, dimension( * )TAU, double precision, dimension( * )WORK, integerINFO)

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

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:

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 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.

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 DGEQRF.

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.

Date:

September 2012

Definition at line 115 of file dorg2r.f.

Author

Generated automatically by Doxygen for LAPACK from the source code.

Referenced By

dorg2r(3) is an alias of dorg2r.f(3).

Sat Nov 16 2013 Version 3.4.2 LAPACK