DORG2L - generate an m by n real matrix Q with orthonormal
columns,
SYNOPSIS
SUBROUTINE DORG2L( M, N, K, A, LDA, TAU, WORK, INFO )
INTEGER INFO, K, LDA, M, N
DOUBLE PRECISION A( LDA, * ), TAU( * ), WORK(
* )
PURPOSE
DORG2L generates an m by n real matrix Q with orthonormal
columns, which is defined as the last n columns of a prod
uct of k elementary reflectors of order m
Q = H(k) . . . H(2) H(1)
as returned by DGEQLF.
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) DOUBLE PRECISION array, dimension
(LDA,N)
On entry, the (n-k+i)-th column must contain the
vector which defines the elementary reflector
H(i), for i = 1,2,...,k, as returned by DGEQLF in
the last 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) DOUBLE PRECISION array, dimension (K)
TAU(i) must contain the scalar factor of the ele
mentary reflector H(i), as returned by DGEQLF.
WORK (workspace) DOUBLE PRECISION array, dimension (N)
INFO (output) INTEGER
= 0: successful exit
gal value
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