Developer Reference

  • 0.9
  • 09/09/2020
  • Public Content
Contents

?larfx

Applies an elementary reflector to a general rectangular matrix, with loop unrolling when the reflector has order less than or equal to 10.

Syntax

lapack_int
LAPACKE_slarfx
(
int
matrix_layout
,
char
side
,
lapack_int
m
,
lapack_int
n
,
const
float
*
v
,
float
tau
,
float
*
c
,
lapack_int
ldc
,
float
*
work
);
lapack_int
LAPACKE_dlarfx
(
int
matrix_layout
,
char
side
,
lapack_int
m
,
lapack_int
n
,
const
double
*
v
,
double
tau
,
double
*
c
,
lapack_int
ldc
,
double
*
work
);
lapack_int
LAPACKE_clarfx
(
int
matrix_layout
,
char
side
,
lapack_int
m
,
lapack_int
n
,
const
lapack_complex_float
*
v
,
lapack_complex_float
tau
,
lapack_complex_float
*
c
,
lapack_int
ldc
,
lapack_complex_float
*
work
);
lapack_int
LAPACKE_zlarfx
(
int
matrix_layout
,
char
side
,
lapack_int
m
,
lapack_int
n
,
const
lapack_complex_double
*
v
,
lapack_complex_double
tau
,
lapack_complex_double
*
c
,
lapack_int
ldc
,
lapack_complex_double
*
work
);
Include Files
  • mkl.h
Description
The routine
?larfx
applies a real/complex elementary reflector
H
to a real/complex
m
-by-
n
matrix
C
, from either the left or the right.
H
is represented in the following forms:
  • H
    =
    I
    -
    tau
    *
    v
    *
    v
    T
    , where
    tau
    is a real scalar and v is a real vector.
  • H
    =
    I
    -
    tau
    *
    v
    *
    v
    H
    , where
    tau
    is a complex scalar and v is a complex vector.
If
tau
= 0
, then
H
is taken to be the unit matrix.
Input Parameters
A
<datatype>
placeholder, if present, is used for the C interface data types in the C interface section above. See C Interface Conventions for the C interface principal conventions and type definitions.
side
If
side
=
'L'
: form
H
*
C
If
side
=
'R'
: form
C
*
H
.
m
The number of rows of the matrix
C
.
n
The number of columns of the matrix
C
.
v
Array, size
(
m
) if
side
=
'L'
or
(
n
) if
side
=
'R'
.
The vector
v
in the representation of
H
.
tau
The value
tau
in the representation of
H
.
c
Array, size
at least max(1,
ldc
*
n
) for column major layout and max (1,
ldc
*
m
) for row major layout
. On entry, the
m
-by-
n
matrix
C
.
ldc
The leading dimension of the array
c
.
lda
(1,
m
).
work
Workspace array, size
(
n
) if
side
=
'L'
or
(
m
) if
side
=
'R'
.
work
is not referenced if
H
has order < 11.
Output Parameters
c
On exit,
C
is overwritten by the matrix
H
*
C
if
side
=
'L'
, or
C
*
H
if
side
=
'R'
.

Product and Performance Information

1

Intel's compilers may or may not optimize to the same degree for non-Intel microprocessors for optimizations that are not unique to Intel microprocessors. These optimizations include SSE2, SSE3, and SSSE3 instruction sets and other optimizations. Intel does not guarantee the availability, functionality, or effectiveness of any optimization on microprocessors not manufactured by Intel. Microprocessor-dependent optimizations in this product are intended for use with Intel microprocessors. Certain optimizations not specific to Intel microarchitecture are reserved for Intel microprocessors. Please refer to the applicable product User and Reference Guides for more information regarding the specific instruction sets covered by this notice.

Notice revision #20110804