- SUBROUTINE SORGR2(
- M, N, K, A, LDA, TAU, WORK, INFO )
- INTEGER INFO, K, LDA, M, N
- REAL A( LDA, * ), TAU( * ), WORK( * )
PURPOSESORGR2 generates an m by n real matrix Q with orthonormal rows, which is defined as the last m rows of a product of k elementary reflectors of order n
Q = H(1) H(2) . . . H(k)
as returned by SGERQF.
- 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) REAL array, dimension (LDA,N)
- On entry, the (m-k+i)-th row must contain the vector which defines the elementary reflector H(i), for i = 1,2,...,k, as returned by SGERQF in the last 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) REAL array, dimension (K)
- TAU(i) must contain the scalar factor of the elementary reflector H(i), as returned by SGERQF.
- WORK (workspace) REAL array, dimension (M)
- INFO (output) INTEGER
= 0: successful exit
< 0: if INFO = -i, the i-th argument has an illegal value