?gemm_compute

Developer Reference for Intel® oneAPI Math Kernel Library for Fortran

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ID 766686

Date 4/28/2026

Version

Public

?gemm_compute

Computes a matrix-matrix product with general matrices where one or both input matrices are stored in a packed data structure and adds the result to a scalar-matrix product.

Syntax

call sgemm_compute(transa, transb, m, n, k, a, lda, b, ldb, beta, C, ldc)

call dgemm_compute(transa, transb, m, n, k, a, lda, b, ldb, beta, C, ldc)

Include Files

mkl.fi

Description

The ?gemm_computecblas_?gemm_compute routine is one of a set of related routines that enable use of an internal packed storage. After calling ?gemm_packcblas_?gemm_pack call ?gemm_computecblas_?gemm_compute to compute

C := 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} , beta is a scalar, 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.

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 ).

transa

CHARACTER*1 . Specifies the form of op(A) used in the matrix multiplication :

If transa = 'N' or 'n' CblasNoTrans op(A) = A .

If transa = 'T' or 't' CblasTrans op(A) = A^{T} .

If transa = 'C' or 'c' CblasConjTrans op(A) = A^{H} .

If transa = 'P' or 'p' CblasPacked the matrix in array a is packed and lda is ignored.

transb

CHARACTER*1 . Specifies the form of op(B) used in the matrix multiplication :

If transb = 'N' or 'n' CblasNoTrans op(B) = B .

If transb = 'T' or 't' CblasTrans op(B) = B^{T} .

If transb = 'C' or 'c' CblasConjTrans op(B) = B^{H} .

If transb = 'P' or 'p' CblasPacked the matrix in array b is packed and ldb is ignored.

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.

a

REAL for sgemm_compute DOUBLE PRECISION for dgemm_compute Array:

lda

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

If transa = 'N' or 'n' , lda must be at least max (1, m) . If transa = 'T' , 't' , 'C' , or 'c' , lda must be at least max (1, k) . If transa = 'P' or 'p' , lda is ignored.

b

REAL for sgemm_compute DOUBLE PRECISION for dgemm_compute Array:

ldb

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

If transb = 'N' or 'n' , ldb must be at least max (1, k) . If transb = 'T' , 't' , 'C' , or 'c' , ldb must be at least max (1, n) . If transb = 'P' or 'p' , ldb is ignored.

beta

REAL for sgemm_compute DOUBLE PRECISION for dgemm_compute Specifies the scalar beta . When beta is equal to zero, then c need not be set on input.

c

REAL for sgemm_compute DOUBLE PRECISION for dgemm_compute 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. Array:

ldc

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

The value of ldc must be at least max (1, m) .

Output Parameters

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

NOTE:

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Developer Reference for Intel® oneAPI Math Kernel Library for Fortran

?gemm_compute

Syntax

Include Files

Description

Input Parameters

Output Parameters