cblas_?gemm

Computes a matrix-matrix product with general matrices.

Syntax

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) = XT, or op(X) = XH,

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) = AT;

if transa=CblasConjTrans, then op(A) = AH.

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) = BT;

if transb=CblasConjTrans, then op(B) = BH.

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.

 

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 the code in in the following links and in the Intel MKL installation directory:

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