Developer Reference

Contents

cblas_?gemv

Computes a matrix-vector product using a general matrix.

Syntax

void
cblas_sgemv
(
const
CBLAS_LAYOUT
Layout
,
const
CBLAS_TRANSPOSE
trans
,
const
MKL_INT
m
,
const
MKL_INT
n
,
const
float
alpha
,
const
float
*a
,
const
MKL_INT
lda
,
const
float
*x
,
const
MKL_INT
incx
,
const
float
beta
,
float
*y
,
const
MKL_INT
incy
);
void
cblas_dgemv
(
const
CBLAS_LAYOUT
Layout
,
const
CBLAS_TRANSPOSE
trans
,
const
MKL_INT
m
,
const
MKL_INT
n
,
const
double
alpha
,
const
double
*a
,
const
MKL_INT
lda
,
const
double
*x
,
const
MKL_INT
incx
,
const
double
beta
,
double
*y
,
const
MKL_INT
incy
);
void
cblas_cgemv
(
const
CBLAS_LAYOUT
Layout
,
const
CBLAS_TRANSPOSE
trans
,
const
MKL_INT
m
,
const
MKL_INT
n
,
const
void
*alpha
,
const
void
*a
,
const
MKL_INT
lda
,
const
void
*x
,
const
MKL_INT
incx
,
const
void
*beta
,
void
*y
,
const
MKL_INT
incy
);
void
cblas_zgemv
(
const
CBLAS_LAYOUT
Layout
,
const
CBLAS_TRANSPOSE
trans
,
const
MKL_INT
m
,
const
MKL_INT
n
,
const
void
*alpha
,
const
void
*a
,
const
MKL_INT
lda
,
const
void
*x
,
const
MKL_INT
incx
,
const
void
*beta
,
void
*y
,
const
MKL_INT
incy
);
Include Files
  • mkl.h
Description
The
?gemv
routines perform a matrix-vector operation defined as:
y
:=
alpha
*
A
*
x
+
beta
*
y
,
or
y
:=
alpha
*
A
'*
x
+
beta
*
y
,
or
y
:=
alpha
*conjg(
A
')*
x
+
beta
*
y
,
where:
alpha
and
beta
are scalars,
x
and
y
are vectors,
A
is an
m
-by-
n
matrix.
Input Parameters
Layout
Specifies whether two-dimensional array storage is row-major (
CblasRowMajor
) or column-major (
CblasColMajor
).
trans
Specifies the operation:
if
trans
=
CblasNoTrans
, then
y
:=
alpha
*
A
*
x
+
beta
*
y
;
if
trans
=
CblasTrans
, then
y
:=
alpha
*
A
'*
x
+
beta
*
y
;
if
trans
=
CblasConjTrans
, then
y
:=
alpha
*conjg(
A
')*
x
+
beta
*
y
.
m
Specifies the number of rows of the matrix
A
. The value of
m
must be at least zero.
n
Specifies the number of columns of the matrix
A
. The value of
n
must be at least zero.
alpha
Specifies the scalar
alpha
.
a
Array, size
lda
*
k
.
For
Layout
=
CblasColMajor
,
k
is
n
. Before entry, the leading
m
-by-
n
part of the array
a
must contain the matrix
A
.
For
Layout
=
CblasRowMajor
,
k
is
m
. Before entry, the leading
n
-by-
m
part of the array
a
must contain the matrix
A
.
lda
Specifies the leading dimension of
a
as declared in the calling (sub)program.
For
Layout
=
CblasColMajor
, the value of
lda
must be at least
max(1,
m
)
.
For
Layout
=
CblasRowMajor
, the value of
lda
must be at least
max(1,
n
)
.
x
Array, size at least
(1+(
n
-1)*abs(
incx
))
when
trans
=
CblasNoTrans
and at least
(1+(
m
- 1)*abs(
incx
))
otherwise. Before entry, the incremented array
x
must contain the vector
x
.
incx
Specifies the increment for the elements of
x
.
The value of
incx
must not be zero.
beta
Specifies the scalar
beta
. When
beta
is set to zero, then
y
need not be set on input.
y
Array, size at least
(1 +(
m
- 1)*abs(
incy
))
when
trans
=
CblasNoTrans
and at least
(1 +(
n
- 1)*abs(
incy
))
otherwise. Before entry with non-zero
beta
, the incremented array
y
must contain the vector
y
.
incy
Specifies the increment for the elements of
y
.
The value of
incy
must not be zero.
Output Parameters
y
Updated vector
y
.

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