DORG2R
November 2006
Purpose
DORG2R 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 DGEQRF.
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 DGEQRF.
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 i-th column must contain the vector which
defines the elementary reflector H(i), for i = 1,2,...,k, as returned by DGEQRF 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) DOUBLE PRECISION array, dimension (K)
TAU(i) must contain the scalar factor of the elementary
reflector H(i), as returned by DGEQRF. |
| WORK |
(workspace) DOUBLE PRECISION array, dimension (N)
|
| INFO |
(output) INTEGER
= 0: successful exit
< 0: if INFO = -i, the i-th argument has an illegal value |