dlarfx(3)

NAME

DLARFX - applie 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 represent

ed 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 represen

tation 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.

LAPACK version 3.0 15 June 2000

DLARFX(3)