SRC/cgeqrt3.f(3) | Library Functions Manual | SRC/cgeqrt3.f(3) |
NAME
SRC/cgeqrt3.f
SYNOPSIS
Functions/Subroutines
recursive subroutine cgeqrt3 (m, n, a, lda, t, ldt, info)
CGEQRT3 recursively computes a QR factorization of a general real or
complex matrix using the compact WY representation of Q.
Function/Subroutine Documentation
recursive subroutine cgeqrt3 (integer m, integer n, complex, dimension( lda, * ) a, integer lda, complex, dimension( ldt, * ) t, integer ldt, integer info)
CGEQRT3 recursively computes a QR factorization of a general real or complex matrix using the compact WY representation of Q.
Purpose:
!> !> CGEQRT3 recursively computes a QR factorization of a complex M-by-N matrix A, !> using the compact WY representation of Q. !> !> Based on the algorithm of Elmroth and Gustavson, !> IBM J. Res. Develop. Vol 44 No. 4 July 2000. !>
Parameters
M
!> M is INTEGER !> The number of rows of the matrix A. M >= N. !>
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 complex M-by-N matrix A. On exit, the elements on and !> above the diagonal contain the N-by-N upper triangular matrix R; the !> elements below the diagonal are the columns of V. See below for !> further details. !>
LDA
!> LDA is INTEGER !> The leading dimension of the array A. LDA >= max(1,M). !>
T
!> T is COMPLEX array, dimension (LDT,N) !> The N-by-N upper triangular factor of the block reflector. !> The elements on and above the diagonal contain the block !> reflector T; the elements below the diagonal are not used. !> See below for further details. !>
LDT
!> LDT is INTEGER !> The leading dimension of the array T. LDT >= max(1,N). !>
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 V stores the elementary reflectors H(i) in the i-th column !> below the diagonal. For example, if M=5 and N=3, the matrix V is !> !> V = ( 1 ) !> ( v1 1 ) !> ( v1 v2 1 ) !> ( v1 v2 v3 ) !> ( v1 v2 v3 ) !> !> where the vi's represent the vectors which define H(i), which are returned !> in the matrix A. The 1's along the diagonal of V are not stored in A. The !> block reflector H is then given by !> !> H = I - V * T * V**H !> !> where V**H is the conjugate transpose of V. !> !> For details of the algorithm, see Elmroth and Gustavson (cited above). !>
Definition at line 131 of file cgeqrt3.f.
Author
Generated automatically by Doxygen for LAPACK from the source code.
Version 3.12.0 | LAPACK |