cblas_?gemm

Developer Reference for Intel® oneAPI Math Kernel Library for C

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ID 766684

Date 3/31/2023

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cblas_?gemm

Computes a matrix-matrix product with general matrices.

Syntax

void cblas_hgemm (const CBLAS_LAYOUT Layout, const CBLAS_TRANSPOSE transa, const CBLAS_TRANSPOSE transb, const MKL_INT m, const MKL_INT n, const MKL_INT k, const MKL_F16 alpha, const MKL_F16 *a, const MKL_INT lda, const MKL_F16 *b, const MKL_INT ldb, const MKL_F16 beta, MKL_F16 *c, const MKL_INT ldc);

void cblas_sgemm (const CBLAS_LAYOUT Layout, const CBLAS_TRANSPOSE transa, const CBLAS_TRANSPOSE transb, const MKL_INT m, 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_dgemm (const CBLAS_LAYOUT Layout, const CBLAS_TRANSPOSE transa, const CBLAS_TRANSPOSE transb, const MKL_INT m, 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_cgemm (const CBLAS_LAYOUT Layout, const CBLAS_TRANSPOSE transa, const CBLAS_TRANSPOSE transb, const MKL_INT m, 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_zgemm (const CBLAS_LAYOUT Layout, const CBLAS_TRANSPOSE transa, const CBLAS_TRANSPOSE transb, const MKL_INT m, 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 ?gemm routines compute a scalar-matrix-matrix product and add the result to a scalar-matrix product, with general matrices. The operation is defined as

C := alpha*op(A)*op(B) + beta*C

where:

op(X) is one of op(X) = X, or op(X) = X^T, or op(X) = X^H,

alpha and beta are scalars,

A, B and C are matrices:

op(A) is an m-by-k matrix,

op(B) is a k-by-n matrix,

C is an m-by-n matrix.

See also:

?gemm for the Fortran language interface to this routine

?gemm3m, BLAS-like extension routines, that use matrix multiplication for similar matrix-matrix operations

Input Parameters

Layout

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

transa

Specifies the form of op(A) used in the matrix multiplication:

if transa=CblasNoTrans, then op(A) = A;
if transa=CblasTrans, then op(A) = A^T;
if transa=CblasConjTrans, then op(A) = A^H.

transb

Specifies the form of op(B) used in the matrix multiplication:

if transb=CblasNoTrans, then op(B) = B;
if transb=CblasTrans, then op(B) = B^T;
if transb=CblasConjTrans, then op(B) = B^H.

m

Specifies the number of rows of the matrix op(A) and of the matrix C. The value of m must be at least zero.

n

Specifies the number of columns of the matrix op(B) and the number of columns of the matrix C. The value of n must be at least zero.

k

Specifies the number of columns of the matrix op(A) and the number of rows of the matrix op(B). The value of k must be at least zero.

alpha

Specifies the scalar alpha.

a

transa=CblasNoTrans

transa=CblasTrans or transa=CblasConjTrans

Layout = CblasColMajor

Array, size lda*k.

Before entry, the leading m-by-k part of the array a must contain the matrix A.

Array, size lda*m.

Before entry, the leading k-by-m part of the array a must contain the matrix A.

Layout = CblasRowMajor

Array, size lda* m.

Before entry, the leading k-by-m part of the array a must contain the matrix A.

Array, size lda*k.

Before entry, the leading m-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.

	transa=CblasNoTrans	transa=CblasTrans or transa=CblasConjTrans
Layout = CblasColMajor	lda must be at least `max(1, m)`.	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, m)`.

b

	transb=CblasNoTrans	transb=CblasTrans or transb=CblasConjTrans
Layout = CblasColMajor	Array, size ldb by n. Before entry, the leading k-by-n part of the array b must contain the matrix `B`.	Array, size ldb by k. Before entry the leading n-by-k part of the array b must contain the matrix `B`.
Layout = CblasRowMajor	Array, size ldb by k. Before entry the leading n-by-k part of the array b must contain the matrix `B`.	Array, size ldb by n. Before entry, the leading k-by-n 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 transb=CblasNoTrans , then ldb must be at least max(1, k), otherwise ldb must be at least max(1, n).

	transb=CblasNoTrans	transb=CblasTrans or transb=CblasConjTrans
Layout = CblasColMajor	ldb must be at least `max(1, k)`.	ldb must be at least `max(1, n)`.
Layout = CblasRowMajor	ldb must be at least `max(1, n)`.	ldb must be at least `max(1, k)`.

beta

Specifies the scalar beta. When beta is equal to zero, then c need not be set on input.

c

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

Layout = CblasColMajor	ldc must be at least `max(1, m)`.
Layout = CblasRowMajor	ldc must be at least `max(1, n)`.

Output Parameters

c: Overwritten by the m-by-n matrix (alpha*op(A)*op(B) + beta*C).

Example

For examples of routine usage, see these code examples in the Intel® oneAPI Math Kernel Library installation directory:

cblas_hgemm: examples\cblas\source\cblas_hgemmx.c
cblas_sgemm: examples\cblas\source\cblas_sgemmx.c
cblas_dgemm: examples\cblas\source\cblas_dgemmx.c
cblas_cgemm: examples\cblas\source\cblas_cgemmx.c
cblas_zgemm: examples\cblas\source\cblas_zgemmx.c

Parent topic: BLAS Level 3 Routines

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Developer Reference for Intel® oneAPI Math Kernel Library for C

cblas_?gemm