- SUBROUTINE DORG2R(
- M, N, K, A, LDA, TAU, WORK, INFO )
- INTEGER INFO, K, LDA, M, N
- DOUBLE PRECISION A( LDA, * ), TAU( * ), WORK( * )
PURPOSEDORG2R 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.
- 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