table of contents
/home/abuild/rpmbuild/BUILD/lapack-3.12.0/SRC/cgelq2.f(3) | Library Functions Manual | /home/abuild/rpmbuild/BUILD/lapack-3.12.0/SRC/cgelq2.f(3) |
NAME¶
/home/abuild/rpmbuild/BUILD/lapack-3.12.0/SRC/cgelq2.f
SYNOPSIS¶
Functions/Subroutines¶
subroutine CGELQ2 (m, n, a, lda, tau, work, info)
CGELQ2 computes the LQ factorization of a general rectangular matrix
using an unblocked algorithm.
Function/Subroutine Documentation¶
subroutine CGELQ2 (integer m, integer n, complex, dimension( lda, * ) a, integer lda, complex, dimension( * ) tau, complex, dimension( * ) work, integer info)¶
CGELQ2 computes the LQ factorization of a general rectangular matrix using an unblocked algorithm.
Purpose:
!> !> CGELQ2 computes an LQ factorization of a complex m-by-n matrix A: !> !> A = ( L 0 ) * Q !> !> where: !> !> Q is a n-by-n orthogonal matrix; !> L is a lower-triangular m-by-m matrix; !> 0 is a m-by-(n-m) zero matrix, if m < n. !> !>
Parameters
M
!> M is INTEGER !> The number of rows of the matrix A. M >= 0. !>
N
!> N is INTEGER !> The number of columns of the matrix A. N >= 0. !>
A
!> A is COMPLEX array, dimension (LDA,N) !> On entry, the m by n matrix A. !> On exit, the elements on and below the diagonal of the array !> contain the m by min(m,n) lower trapezoidal matrix L (L is !> lower triangular if m <= n); the elements above the diagonal, !> with the array TAU, represent the unitary matrix Q as a !> product of elementary reflectors (see Further Details). !>
LDA
!> LDA is INTEGER !> The leading dimension of the array A. LDA >= max(1,M). !>
TAU
!> TAU is COMPLEX array, dimension (min(M,N)) !> The scalar factors of the elementary reflectors (see Further !> Details). !>
WORK
!> WORK is COMPLEX array, dimension (M) !>
INFO
!> INFO is INTEGER !> = 0: successful exit !> < 0: if INFO = -i, the i-th argument had an illegal value !>
Author
Univ. of Tennessee
Univ. of California Berkeley
Univ. of Colorado Denver
NAG Ltd.
Further Details:
!> !> The matrix Q is represented as a product of elementary reflectors !> !> Q = H(k)**H . . . H(2)**H H(1)**H, where k = min(m,n). !> !> Each H(i) has the form !> !> H(i) = I - tau * v * v**H !> !> where tau is a complex scalar, and v is a complex vector with !> v(1:i-1) = 0 and v(i) = 1; conjg(v(i+1:n)) is stored on exit in !> A(i,i+1:n), and tau in TAU(i). !>
Definition at line 128 of file cgelq2.f.
Author¶
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