dlarfx.f (3) Linux Manual Page

dlarfx.f –

Synopsis

Functions/Subroutines

subroutine dlarfx (SIDE, M, N, V, TAU, C, LDC, WORK)
DLARFX applies an elementary reflector to a general rectangular matrix, with loop unrolling when the reflector has order ≤ 10.

Function/Subroutine Documentation

subroutine dlarfx (characterSIDE, integerM, integerN, double precision, dimension( * )V, double precisionTAU, double precision, dimension( ldc, * )C, integerLDC, double precision, dimension( * )WORK)

DLARFX applies an elementary reflector to a general rectangular matrix, with loop unrolling when the reflector has order ≤ 10.

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**T

 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.

 

Parameters:

SIDE

 SIDE is CHARACTER*1

 = ‘L’: form H * C

 = ‘R’: form C * H

M

 M is INTEGER

 The number of rows of the matrix C.

N

 N is INTEGER

 The number of columns of the matrix C.

V

 V is DOUBLE PRECISION array, dimension (M) if SIDE = ‘L’

 or (N) if SIDE = ‘R’

 The vector v in the representation of H.

TAU

 TAU is DOUBLE PRECISION

 The value tau in the representation of H.

C

 C is 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

 LDC is INTEGER

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

WORK

 WORK is DOUBLE PRECISION array, dimension

 (N) if SIDE = ‘L’

 or (M) if SIDE = ‘R’

 WORK is not referenced if H has order < 11.

 

Author:

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

Date:

September 2012

Definition at line 121 of file dlarfx.f.

Author

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