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 ele
mentary 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 ille
gal value
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