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 )
#include <sunperf.h>
void sorgqr(int m, int n, int k, float *sa, int lda, float
*tau, int *info) ;
PURPOSE
SORGQR generates an M-by-N real matrix Q with orthonormal
columns, which is defined as the first N columns of a pro-
duct 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 ele-
mentary reflector H(i), as returned by SGEQRF.
WORK (workspace/output) 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 ille-
gal value
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