dorgr2 (l)  Linux Man Pages
dorgr2: generates an m by n real matrix Q with orthonormal rows,
NAME
DORGR2  generates an m by n real matrix Q with orthonormal rows,SYNOPSIS
 SUBROUTINE DORGR2(
 M, N, K, A, LDA, TAU, WORK, INFO )
 INTEGER INFO, K, LDA, M, N
 DOUBLE PRECISION A( LDA, * ), TAU( * ), WORK( * )
PURPOSE
DORGR2 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 nQ
as returned by DGERQF.
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 (mk+i)th row must contain the vector which defines the elementary reflector H(i), for i = 1,2,...,k, as returned by DGERQF 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) DOUBLE PRECISION array, dimension (K)
 TAU(i) must contain the scalar factor of the elementary reflector H(i), as returned by DGERQF.
 WORK (workspace) DOUBLE PRECISION array, dimension (M)
 INFO (output) INTEGER

= 0: successful exit
< 0: if INFO = i, the ith argument has an illegal value