Developer Reference for Intel® oneAPI Math Kernel Library - C

Developer Reference

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

cblas_?syr2k

Performs a symmetric rank-2k update.

Syntax

void
cblas_ssyr2k
(
const
CBLAS_LAYOUT
Layout
,
const
CBLAS_UPLO
uplo
,
const
CBLAS_TRANSPOSE
trans
,
const
MKL_INT
n
,
const
MKL_INT
k
,
const
float
alpha
,
const
float
*a
,
const
MKL_INT
lda
,
const
float
*b
,
const
MKL_INT
ldb
,
const
float
beta
,
float
*c
,
const
MKL_INT
ldc
);
void
cblas_dsyr2k
(
const
CBLAS_LAYOUT
Layout
,
const
CBLAS_UPLO
uplo
,
const
CBLAS_TRANSPOSE
trans
,
const
MKL_INT
n
,
const
MKL_INT
k
,
const
double
alpha
,
const
double
*a
,
const
MKL_INT
lda
,
const
double
*b
,
const
MKL_INT
ldb
,
const
double
beta
,
double
*c
,
const
MKL_INT
ldc
);
void
cblas_csyr2k
(
const
CBLAS_LAYOUT
Layout
,
const
CBLAS_UPLO
uplo
,
const
CBLAS_TRANSPOSE
trans
,
const
MKL_INT
n
,
const
MKL_INT
k
,
const
void
*alpha
,
const
void
*a
,
const
MKL_INT
lda
,
const
void
*b
,
const
MKL_INT
ldb
,
const
void
*beta
,
void
*c
,
const
MKL_INT
ldc
);
void
cblas_zsyr2k
(
const
CBLAS_LAYOUT
Layout
,
const
CBLAS_UPLO
uplo
,
const
CBLAS_TRANSPOSE
trans
,
const
MKL_INT
n
,
const
MKL_INT
k
,
const
void
*alpha
,
const
void
*a
,
const
MKL_INT
lda
,
const
void
*b
,
const
MKL_INT
ldb
,
const
void
*beta
,
void
*c
,
const
MKL_INT
ldc
);
Include Files
  • mkl.h
Description
The
?syr2k
 routines perform a rank-2k
matrix-matrix operation for a symmetric matrix
C
 using general matrices
A
 and
B
The
 operation is defined as:
C := alpha*A*B' + alpha*B*A' + beta*C,
or 
C := alpha*A'*B + alpha*B'*A + beta*C,
where:
alpha
 and
beta
 are scalars,
C
 is an
n
-by-
n
 symmetric matrix,
A
 and
B
 are
n
-by-
k
 matrices in the first case, and
k
-by-
n
 matrices in the second case.
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
c
 is used.
If
uplo
 =
CblasUpper
, then the upper triangular part of the array
c
 is used.
If
uplo
 =
CblasLower
, then the low triangular part of the array
c
 is used.
trans
Specifies the operation:
if
trans
=
CblasNoTrans
, then
C
 :=
alpha
*
A
*
B
'+
alpha
*
B
*
A
'+
beta
*
C
;
if
trans
=
CblasTrans
, then
C
 :=
alpha
*
A
'*
B
 +
alpha
*
B
'*
A
 +
beta
*
C
;
if
trans
=
CblasConjTrans
, then
C
 :=
alpha
*
A
'*
B
 +
alpha
*
B
'*
A
 +
beta
*
C
.
n
Specifies the order of the matrix
C
.
The value of
n
 must be at least zero.
k
On entry with
trans
=
CblasNoTrans
,
k
 specifies the number of columns of the matrices
A
 and
B
, and on entry with
trans
=
CblasTrans
 or
trans
=
CblasConjTrans
,
k
 specifies the number of rows of the matrices
A
 and
B
.
 The value of
k
 must be at least zero.
alpha
Specifies the scalar
alpha
.
a
trans
=
CblasNoTrans
trans
=
CblasConjTrans
Layout
 =
CblasColMajor
Array, size
lda
*
k
.
Before entry, the leading
n
-by-
k
 part of the array
a
 must contain the matrix
A
.
Array, size
lda
*
n
.
Before entry, the leading
k
-by-
n
 part of the array
a
 must contain the matrix
A
.
Layout
 =
CblasRowMajor
Array, size
lda
*
n
.
Before entry, the leading
k
-by-
n
 part of the array
a
 must contain the matrix
A
.
Array, size
lda
*
k
.
Before entry, the leading
n
-by-
k
 part of the array
a
 must contain the matrix
A
.
lda
Specifies the leading dimension of
a
 as declared in the calling (sub)program.
trans
=
CblasNoTrans
trans
=
CblasConjTrans
Layout
 =
CblasColMajor
lda
 must be at least
max(1,
n
)
.
lda
 must be at least
max(1,
k
)
Layout
 =
CblasRowMajor
lda
 must be at least
max(1,
k
)
lda
 must be at least
max(1,
n
)
.
b
trans
=
CblasNoTrans
trans
=
CblasConjTrans
Layout
 =
CblasColMajor
Array, size
ldb
*
k
.
Before entry, the leading
n
-by-
k
 part of the array
b
 must contain the matrix
B
.
Array, size
ldb
*
n
.
Before entry, the leading
k
-by-
n
 part of the array
b
 must contain the matrix
B
.
Layout
 =
CblasRowMajor
Array, size
lda
*
n
.
Before entry, the leading
k
-by-
n
 part of the array
b
 must contain the matrix
B
.
Array, size
lda
*
k
.
Before entry, the leading
n
-by-
k
 part of the array
b
 must contain the matrix
B
.
ldb
Specifies the leading dimension of
a
 as declared in the calling (sub)program.
trans
=
CblasNoTrans
trans
=
CblasConjTrans
Layout
 =
CblasColMajor
ldb
 must be at least
max(1,
n
)
.
ldb
 must be at least
max(1,
k
)
Layout
 =
CblasRowMajor
ldb
 must be at least
max(1,
k
)
ldb
 must be at least
max(1,
n
)
.
beta
Specifies the scalar
beta
.
c
Array, size
ldc
*
n
. Before entry with
uplo
 =
CblasUpper
, the leading
n
-by-
n
 upper triangular part of the array
c
 must contain the upper triangular part of the symmetric matrix and the strictly lower triangular part of
c
 is not referenced.
Before entry with
uplo
 =
CblasLower
, the leading
n
-by-
n
 lower triangular part of the array
c
 must contain the lower triangular part of the symmetric matrix and the strictly upper triangular part of
c
 is not referenced.
ldc
Specifies the leading dimension of
c
 as declared in the calling (sub)program. The value of
ldc
 must be at least
max(1,
n
)
.
Output Parameters
c
With
uplo
 =
CblasUpper
, the upper triangular part of the array
c
 is overwritten by the upper triangular part of the updated matrix.
With
uplo
 =
CblasLower
, the lower triangular part of the array
c
 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