?gemm_pack

Developer Reference for Intel® oneAPI Math Kernel Library for Fortran

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ID 766686

Date 4/28/2026

Version

Public

?gemm_pack

Performs scaling and packing of the matrix into the previously allocated buffer.

Syntax

call sgemm_pack(identifier, trans, m, n, k, alpha, src, ld, dest)

call dgemm_pack(identifier, trans, m, n, k, alpha, src, ld, dest)

Include Files

mkl.fi

Description

The ?gemm_packcblas_?gemm_pack routine is one of a set of related routines that enable use of an internal packed storage. Call ?gemm_packcblas_?gemm_pack after you allocate a buffer whose size is given by ?gemm_pack_get_sizecblas_?gemm_pack_getsize . The ?gemm_packcblas_?gemm_pack routine scales the identified matrix by alpha and packs it into the buffer allocated previously.

NOTE:

Do not copy the packed matrix to a different address because the internal implementation depends on the alignment of internally-stored metadata.

The ?gemm_packcblas_?gemm_pack routine performs this operation:

dest := alpha*op(src) as part of the computation C := alpha*op(A)*op(B) + beta*C

where: op(X) is one of the operations op(X) = X , op(X) = X^{T} , or op(X) = X^{H} , alpha and beta are scalars, src is a matrix, A , B , and C are matrices op(src) is an m -by- k matrix if identifier = 'A' or 'a' CblasAMatrix , op(src) is a k -by- n matrix if identifier = 'B' or 'b' CblasBMatrix , dest is an internal packed storage buffer.

NOTE:

You must use the same value of the Layout parameter for the entire sequence of related cblas_?gemm_pack and cblas_?gemm_compute calls.

For best performance, use the same number of threads for packing and for computing.

If packing for both A and B matrices, you must use the same number of threads for packing A as for packing B .

Input Parameters

Layout

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

identifier

CHARACTER*1 . Specifies which matrix is to be packed:

If identifier = 'A' or 'a' CblasAMatrix , the routine allocates storage to pack matrix A .

If identifier = 'B' or 'b' CblasBMatrix , the routine allocates storage to pack matrix B .

trans

CHARACTER*1 . Specifies the form of op(src) used in the packing:

If trans = 'N' or 'n' CblasNoTrans op(src) = src .

If trans = 'T' or 't' CblasTrans op(src) = src^{T} .

If trans = 'C' or 'c' CblasConjTrans op(src) = src^{H} .

m

INTEGER . 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

INTEGER . 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

INTEGER . 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

REAL for sgemm_pack DOUBLE PRECISION for dgemm_pack Specifies the scalar alpha .

src

REAL for sgemm_pack DOUBLE PRECISION for dgemm_pack Array:

ld

INTEGER. Specifies the leading dimension of src as declared in the calling (sub)program.

dest

POINTER . Scaled and packed internal storage buffer.

Output Parameters

dest: Overwritten by the matrix alpha*op(src) .

NOTE:

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Developer Reference for Intel® oneAPI Math Kernel Library for Fortran

?gemm_pack

Syntax

Include Files

Description

Input Parameters

Output Parameters