cung2l.f3
Usage
Functions/Subroutines
subroutine cung2l (m, n, k, a, lda, tau, work, info)
CUNG2L generates all or part of the unitary matrix Q from a QL factorization determined by cgeqlf (unblocked algorithm).
Function/Subroutine Documentation
subroutine cung2l (integer m, integer n, integer k, complex, dimension( lda, * ) a, integer lda, complex, dimension( * ) tau, complex, dimension( * ) work, integer info)
CUNG2L generates all or part of the unitary matrix Q from a QL factorization determined by cgeqlf (unblocked algorithm).
Purpose:
!> !> CUNG2L generates an m by n complex matrix Q with orthonormal columns, !> which is defined as the last n columns of a product of k elementary !> reflectors of order m !> !> Q = H(k) . . . H(2) H(1) !> !> as returned by CGEQLF. !>
Parameters
M
!> 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. M >= N >= 0. !>
K
!> K is INTEGER !> The number of elementary reflectors whose product defines the !> matrix Q. N >= K >= 0. !>
A
!> A is COMPLEX array, dimension (LDA,N) !> On entry, the (n-k+i)-th column must contain the vector which !> defines the elementary reflector H(i), for i = 1,2,...,k, as !> returned by CGEQLF in the last k columns 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 CGEQLF. !>
WORK
!> WORK is COMPLEX array, dimension (N) !>
INFO
!> INFO is INTEGER !> = 0: successful exit !> < 0: if INFO = -i, the i-th argument has an illegal value !>
Author
Univ. of Tennessee
Univ. of California Berkeley
Univ. of Colorado Denver
NAG Ltd.
Definition at line 113 of file cung2l.f.
Releases
4 releases since Debian 7 (Wheezy); the text changed 3 times.