NAME
DORGL2 - generates an m by n real matrix Q with orthonormal rows,
SYNOPSIS
- SUBROUTINE DORGL2(
-
M, N, K, A, LDA, TAU, WORK, INFO )
- INTEGER
-
INFO, K, LDA, M, N
- DOUBLE
-
PRECISION A( LDA, * ), TAU( * ), WORK( * )
PURPOSE
DORGL2 generates an m by n real matrix Q with orthonormal rows, which is defined as the first m rows of a product of k elementary reflectors of order n
Q = H(k) . . . H(2) H(1)
as returned by DGELQF.
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. N >= M.
- K (input) INTEGER
-
The number of elementary reflectors whose product defines the matrix Q. M >= K >= 0.
- A (input/output) DOUBLE PRECISION array, dimension (LDA,N)
-
On entry, the i-th row must contain the vector which defines the elementary reflector H(i), for i = 1,2,...,k, as returned by DGELQF in the first k rows 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 elementary reflector H(i), as returned by DGELQF.
- WORK (workspace) DOUBLE PRECISION array, dimension (M)
- INFO (output) INTEGER
-
= 0: successful exit
< 0: if INFO = -i, the i-th argument has an illegal value