man sorg2r (Fonctions bibliothèques) - generate an m by n real matrix Q with orthonormal columns,

NAME

SORG2R - generate an m by n real matrix Q with orthonormal columns,

SYNOPSIS

SUBROUTINE SORG2R(
M, N, K, A, LDA, TAU, WORK, INFO )
INTEGER INFO, K, LDA, M, N
REAL A( LDA, * ), TAU( * ), WORK( * )

PURPOSE

SORG2R 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 SGEQRF.

ARGUMENTS

M (input) INTEGER
The number of rows of the matrix Q. M >= 0.
N (input) INTEGER
The number of columns of the matrix Q. M >= N >= 0.
K (input) INTEGER
The number of elementary reflectors whose product defines the matrix Q. N >= K >= 0.
A (input/output) REAL 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 SGEQRF in the first k columns of its array argument A. On exit, the m-by-n matrix Q.
LDA (input) INTEGER
The first dimension of the array A. LDA >= max(1,M).
TAU (input) REAL array, dimension (K)
TAU(i) must contain the scalar factor of the elementary reflector H(i), as returned by SGEQRF.
WORK (workspace) REAL array, dimension (N)
INFO (output) INTEGER
= 0: successful exit

< 0: if INFO = -i, the i-th argument has an illegal value