dorg2r.f (3) Linux Manual 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

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