.TH SORGQR 1 "November 2006" " LAPACK routine (version 3.1) " " LAPACK routine (version 3.1) "
.SH NAME
SORGQR - an M-by-N real matrix Q with orthonormal columns,
.SH SYNOPSIS
.TP 19
SUBROUTINE SORGQR(
M, N, K, A, LDA, TAU, WORK, LWORK, INFO )
.TP 19
.ti +4
INTEGER
INFO, K, LDA, LWORK, M, N
.TP 19
.ti +4
REAL
A( LDA, * ), TAU( * ), WORK( * )
.SH 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
.br
Q = H(1) H(2) . . . H(k)
.br
as returned by SGEQRF.
.br
.SH ARGUMENTS
.TP 8
M (input) INTEGER
The number of rows of the matrix Q. M >= 0.
.TP 8
N (input) INTEGER
The number of columns of the matrix Q. M >= N >= 0.
.TP 8
K (input) INTEGER
The number of elementary reflectors whose product defines the
matrix Q. N >= K >= 0.
.TP 8
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.
.TP 8
LDA (input) INTEGER
The first dimension of the array A. LDA >= max(1,M).
.TP 8
TAU (input) REAL array, dimension (K)
TAU(i) must contain the scalar factor of the elementary
reflector H(i), as returned by SGEQRF.
.TP 8
WORK (workspace/output) REAL array, dimension (MAX(1,LWORK))
On exit, if INFO = 0, WORK(1) returns the optimal LWORK.
.TP 8
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.
If LWORK = -1, then a workspace query is assumed; the routine
only calculates the optimal size of the WORK array, returns
this value as the first entry of the WORK array, and no error
message related to LWORK is issued by XERBLA.
.TP 8
INFO (output) INTEGER
= 0: successful exit
.br
< 0: if INFO = -i, the i-th argument has an illegal value