Developer Reference for Intel® oneAPI Math Kernel Library - C

Developer Reference

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

cblas_?syr2

Performs
 a rank-2 update of a symmetric matrix.

Syntax

void
cblas_ssyr2
(
const
CBLAS_LAYOUT
Layout
,
const
CBLAS_UPLO
uplo
,
const
MKL_INT
n
,
const
float
alpha
,
const
float
*x
,
const
MKL_INT
incx
,
const
float
*y
,
const
MKL_INT
incy
,
float
*a
,
const
MKL_INT
lda
);
void
cblas_dsyr2
(
const
CBLAS_LAYOUT
Layout
,
const
CBLAS_UPLO
uplo
,
const
MKL_INT
n
,
const
double
alpha
,
const
double
*x
,
const
MKL_INT
incx
,
const
double
*y
,
const
MKL_INT
incy
,
double
*a
,
const
MKL_INT
lda
);
Include Files
  • mkl.h
Description
The
?syr2
 routines perform a matrix-vector operation defined as 
A := alpha*x*y'+ alpha*y*x' + A,
where:
alpha
 is scalar,
x
 and
y
 are
n
-element vectors,
A
 is an
n
-by-
n
 symmetric matrix.
Input Parameters
Layout
Specifies whether two-dimensional array storage is row-major (
CblasRowMajor
) or column-major (
CblasColMajor
).
uplo
Specifies whether the upper or lower triangular part of the array
a
 is used.
If
uplo
 =
CblasUpper
, then the upper triangular part of the array
a
 is used.
If
uplo
 =
CblasLower
, then the low triangular part of the array
a
 is used.
n
Specifies the order of the matrix
A
. The value of
n
 must be at least zero.
alpha
Specifies the scalar
alpha
.
x
Array, size at least
(1 + (
n
 - 1)*abs(
incx
))
. Before entry, the incremented array
x
 must contain the
n
-element vector
x
.
incx
Specifies the increment for the elements of
x
.
The value of
incx
 must not be zero.
y
Array, size at least
(1 + (
n
 - 1)*abs(
incy
))
. Before entry, the incremented array
y
 must contain the
n
-element vector
y
.
incy
Specifies the increment for the elements of
y
. The value of
incy
 must not be zero.
a
Array, size
lda
*
n
.
Before entry with
uplo
 =
CblasUpper
, the leading
n
-by-
n
 upper triangular part of the array
a
 must contain the upper triangular part of the symmetric matrix and the strictly lower triangular part of
a
 is not referenced.
Before entry with
uplo
 =
CblasLower
, the leading
n
-by-
n
 lower triangular part of the array
a
 must contain the lower triangular part of the symmetric matrix and the strictly upper triangular part of
a
 is not referenced.
lda
Specifies the leading dimension of
a
 as declared in the calling (sub)program. The value of
lda
 must be at least
max(1,
n
)
.
Output Parameters
a
With
uplo
 =
CblasUpper
, the upper triangular part of the array
a
 is overwritten by the upper triangular part of the updated matrix.
With
uplo
 =
CblasLower
, the lower triangular part of the array
a
 is overwritten by the lower triangular part of the updated matrix.

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