dlarfx

Langue: en

Version: 326797 (ubuntu - 08/07/09)

Section: 3 (Bibliothèques de fonctions)

Sommaire

NAME

DLARFX - applies a real elementary reflector H to a real m by n matrix C, from either the left or the right

SYNOPSIS

SUBROUTINE DLARFX(
SIDE, M, N, V, TAU, C, LDC, WORK )

    
CHARACTER SIDE

    
INTEGER LDC, M, N

    
DOUBLE PRECISION TAU

    
DOUBLE PRECISION C( LDC, * ), V( * ), WORK( * )

PURPOSE

DLARFX applies a real elementary reflector H to a real m by n matrix C, from either the left or the right. H is represented in the form


      H = I - tau * v * v'

where tau is a real scalar and v is a real vector.

If tau = 0, then H is taken to be the unit matrix

This version uses inline code if H has order < 11.

ARGUMENTS

SIDE (input) CHARACTER*1
= 'L': form H * C
= 'R': form C * H
M (input) INTEGER
The number of rows of the matrix C.
N (input) INTEGER
The number of columns of the matrix C.
V (input) DOUBLE PRECISION array, dimension (M) if SIDE = 'L'
or (N) if SIDE = 'R' The vector v in the representation of H.
TAU (input) DOUBLE PRECISION
The value tau in the representation of H.
C (input/output) DOUBLE PRECISION array, dimension (LDC,N)
On entry, the m by n matrix C. On exit, C is overwritten by the matrix H * C if SIDE = 'L', or C * H if SIDE = 'R'.
LDC (input) INTEGER
The leading dimension of the array C. LDA >= (1,M).
WORK (workspace) DOUBLE PRECISION array, dimension
(N) if SIDE = 'L' or (M) if SIDE = 'R' WORK is not referenced if H has order < 11.