SORGQR(l) LAPACK routine (version 1.1) SORGQR(l)
NAME
SORGQR - generate an M-by-N real matrix Q with orthonormal columns,
SYNOPSIS
SUBROUTINE SORGQR( M, N, K, A, LDA, TAU, WORK, LWORK, INFO )
INTEGER INFO, K, LDA, LWORK, M, N
REAL A( LDA, * ), TAU( * ), WORK( LWORK )
PURPOSE
SORGQR 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 (LWORK)
On exit, if INFO = 0, WORK(1) returns the optimal LWORK.
LWORK (input) INTEGER
The dimension of the array WORK. LWORK >= max(1,N). For optimum
performance LWORK >= N*NB, where NB is the optimal blocksize.
INFO (output) INTEGER
= 0: successful exit
< 0: if INFO = -i, the i-th argument has an illegal value
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