cblas_?hemm

Developer Reference for Intel® oneAPI Math Kernel Library for C

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ID 766684

Date 12/16/2022

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cblas_?hemm

Computes a matrix-matrix product where one input matrix is Hermitian.

Syntax

void cblas_chemm (const CBLAS_LAYOUT Layout, const CBLAS_SIDE side, const CBLAS_UPLO uplo, const MKL_INT m, const MKL_INT n, 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_zhemm (const CBLAS_LAYOUT Layout, const CBLAS_SIDE side, const CBLAS_UPLO uplo, const MKL_INT m, const MKL_INT n, 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 ?hemm routines compute a scalar-matrix-matrix product using a Hermitian matrix A and a general matrix B and add the result to a scalar-matrix product using a general matrix C. The operation is defined as

C := alpha*A*B + beta*C

C := alpha*B*A + beta*C

where:

alpha and beta are scalars,

A is a Hermitian matrix,

B and C are m-by-n matrices.

Input Parameters

Layout

Specifies whether two-dimensional array storage is row-major (CblasRowMajor) or column-major (CblasColMajor).

side

Specifies whether the Hermitian matrix A appears on the left or right in the operation as follows:

if side = CblasLeft, then C := alpha*A*B + beta*C;

if side = CblasRight, then C := alpha*B*A + beta*C.

uplo

Specifies whether the upper or lower triangular part of the Hermitian matrix A is used:

If uplo = CblasUpper, then the upper triangular part of the Hermitian matrix A is used.

If uplo = CblasLower, then the low triangular part of the Hermitian matrix A is used.

m

Specifies the number of rows of the matrix C.

The value of m must be at least zero.

n

Specifies the number of columns of the matrix C.

The value of n must be at least zero.

alpha

Specifies the scalar alpha.

a

Array, size lda* ka, where ka is m when side = CblasLeft and is n otherwise. Before entry with side = CblasLeft, the m-by-m part of the array a must contain the Hermitian matrix, such that when uplo = CblasUpper, the leading m-by-m upper triangular part of the array a must contain the upper triangular part of the Hermitian matrix and the strictly lower triangular part of a is not referenced, and when uplo = CblasLower, the leading m-by-m lower triangular part of the array a must contain the lower triangular part of the Hermitian matrix, and the strictly upper triangular part of a is not referenced.

Before entry with side = CblasRight, the n-by-n part of the array a must contain the Hermitian matrix, such that when uplo = CblasUpper, the leading n-by-n upper triangular part of the array a must contain the upper triangular part of the Hermitian matrix and the strictly lower triangular part of a is not referenced, and when uplo = CblasLower, the leading n-by-n lower triangular part of the array a must contain the lower triangular part of the Hermitian matrix, and the strictly upper triangular part of a is not referenced. The imaginary parts of the diagonal elements need not be set, they are assumed to be zero.

lda

Specifies the leading dimension of a as declared in the calling (sub) program. When side = CblasLeft then lda must be at least max(1, m), otherwise lda must be at least max(1,n).

b

For Layout = CblasColMajor: array, size ldb*n. The leading m-by-n part of the array b must contain the matrix B.

For Layout = CblasRowMajor: array, size ldb*m. The leading n-by-m part of the array b must contain the matrix B

ldb

Specifies the leading dimension of b as declared in the calling (sub)program.When Layout = CblasColMajor, ldb must be at least max(1, m); otherwise, ldb must be at least max(1, n) .

beta

Specifies the scalar beta.

When beta is supplied as zero, then c need not be set on input.

c

For Layout = CblasColMajor: array, size ldc*n. Before entry, the leading m-by-n part of the array c must contain the matrix C, except when beta is zero, in which case c need not be set on entry.

For Layout = CblasRowMajor: array, size ldc*m. Before entry, the leading n-by-m part of the array c must contain the matrix C, except when beta is zero, in which case c need not be set on entry.

ldc

Specifies the leading dimension of c as declared in the calling (sub)program. When Layout = CblasColMajor, ldc must be at least max(1, m); otherwise, ldc must be at least max(1, n) .

Output Parameters

:
c: Overwritten by the m-by-n updated matrix.

Parent topic: BLAS Level 3 Routines

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Developer Reference for Intel® oneAPI Math Kernel Library for C

cblas_?hemm