dlarfx.f - Man Page

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.

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. LDC >= (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.

Definition at line 119 of file dlarfx.f.