dlarfx (l) - Linux Manuals

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

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 )

    

IMPLICIT NONE

    

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 * vaq
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

= aqLaq: form H * C
= aqRaq: 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 = aqLaq

or (N) if SIDE = aqRaq 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 = aqLaq, or C * H if SIDE = aqRaq.

LDC (input) INTEGER

The leading dimension of the array C. LDA >= (1,M).

WORK (workspace) DOUBLE PRECISION array, dimension

(N) if SIDE = aqLaq or (M) if SIDE = aqRaq WORK is not referenced if H has order < 11.