subroutine cungr2 (M, N, K, A, LDA, TAU, WORK, INFO)
CUNGR2 generates all or part of the unitary matrix Q from an RQ factorization determined by cgerqf (unblocked algorithm).
CUNGR2 generates all or part of the unitary matrix Q from an RQ factorization determined by cgerqf (unblocked algorithm).
Purpose:
CUNGR2 generates an m by n complex 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 H(2)**H . . . H(k)**H as returned by CGERQF.
Parameters:
M is INTEGER The number of rows of the matrix Q. M >= 0.
N
N is INTEGER The number of columns of the matrix Q. N >= M.
K
K is INTEGER The number of elementary reflectors whose product defines the matrix Q. M >= K >= 0.
A
A is COMPLEX 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 CGERQF in the last k rows of its array argument A. On exit, the m-by-n matrix Q.
LDA
LDA is INTEGER The first dimension of the array A. LDA >= max(1,M).
TAU
TAU is COMPLEX array, dimension (K) TAU(i) must contain the scalar factor of the elementary reflector H(i), as returned by CGERQF.
WORK
WORK is COMPLEX array, dimension (M)
INFO
INFO is INTEGER = 0: successful exit < 0: if INFO = -i, the i-th argument has an illegal value
Author:
Univ. of California Berkeley
Univ. of Colorado Denver
NAG Ltd.
Date:
Definition at line 116 of file cungr2.f.
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