dorg2r.f File Reference

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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).

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Function/Subroutine Documentation

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.

Date:

September 2012

Definition at line 115 of file dorg2r.f.

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