# Name

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

# Synopsis

`#include "hpl.h"`

`void`

`HPL_dgemm(`

`const enum HPL_ORDER`

`ORDER`

,
`const enum HPL_TRANS`

`TRANSA`

,
`const enum HPL_TRANS`

`TRANSB`

,
`const int`

`M`

,
`const int`

`N`

,
`const int`

`K`

,
`const double`

`ALPHA`

,
`const double *`

`A`

,
`const int`

`LDA`

,
`const double *`

`B`

,
`const int`

`LDB`

,
`const double`

`BETA`

,
`double *`

`C`

,
`const int`

`LDC`

`);`

# Description

**HPL_dgemm**performs one of the matrix-matrix operations C := alpha * op( A ) * op( B ) + beta * C where op( X ) is one of op( X ) = X or op( X ) = X^T. Alpha and beta are scalars, and A, B and C are matrices, with op(A) an m by k matrix, op(B) a k by n matrix and C an m by n matrix.

# Arguments

ORDER (local input) const enum HPL_ORDER On entry, ORDER specifies the storage format of the operands as follows: ORDER = HplRowMajor, ORDER = HplColumnMajor.

TRANSA (local input) const enum HPL_TRANS On entry, TRANSA specifies the form of op(A) to be used in the matrix-matrix operation follows: TRANSA==HplNoTrans : op( A ) = A, TRANSA==HplTrans : op( A ) = A^T, TRANSA==HplConjTrans : op( A ) = A^T.

TRANSB (local input) const enum HPL_TRANS On entry, TRANSB specifies the form of op(B) to be used in the matrix-matrix operation follows: TRANSB==HplNoTrans : op( B ) = B, TRANSB==HplTrans : op( B ) = B^T, TRANSB==HplConjTrans : op( B ) = B^T.

M (local input) const int On entry, M specifies the number of rows of the matrix op(A) and of the matrix C. M must be at least zero.

N (local input) const int On entry, N specifies the number of columns of the matrix op(B) and the number of columns of the matrix C. N must be at least zero.

K (local input) const int On entry, K specifies the number of columns of the matrix op(A) and the number of rows of the matrix op(B). K must be be at least zero.

ALPHA (local input) const double On entry, ALPHA specifies the scalar alpha. When ALPHA is supplied as zero then the elements of the matrices A and B need not be set on input.

A (local input) const double * On entry, A is an array of dimension (LDA,ka), where ka is k when TRANSA==HplNoTrans, and is m otherwise. Before entry with TRANSA==HplNoTrans, the leading m by k part of the array A must contain the matrix A, otherwise the leading k by m part of the array A must contain the matrix A.

LDA (local input) const int On entry, LDA specifies the first dimension of A as declared in the calling (sub) program. When TRANSA==HplNoTrans then LDA must be at least max(1,m), otherwise LDA must be at least max(1,k).

B (local input) const double * On entry, B is an array of dimension (LDB,kb), where kb is n when TRANSB==HplNoTrans, and is k otherwise. Before entry with TRANSB==HplNoTrans, the leading k by n part of the array B must contain the matrix B, otherwise the leading n by k part of the array B must contain the matrix B.

LDB (local input) const int On entry, LDB specifies the first dimension of B as declared in the calling (sub) program. When TRANSB==HplNoTrans then LDB must be at least max(1,k), otherwise LDB must be at least max(1,n).

BETA (local input) const double On entry, BETA specifies the scalar beta. When BETA is supplied as zero then the elements of the matrix C need not be set on input.

C (local input/output) double * On entry, C is an array of dimension (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. On exit, the array C is overwritten by the m by n matrix ( alpha*op( A )*op( B ) + beta*C ).

LDC (local input) const int On entry, LDC specifies the first dimension of C as declared in the calling (sub) program. LDC must be at least max(1,m).

# Example

`#include "hpl.h"`

int main(int argc, char *argv[]) { double a[2*2], b[2*2], c[2*2]; a[0] = 1.0; a[1] = 2.0; a[2] = 3.0; a[3] = 3.0; b[0] = 2.0; b[1] = 1.0; b[2] = 1.0; b[3] = 2.0; c[0] = 4.0; c[1] = 3.0; c[2] = 2.0; c[3] = 1.0; HPL_dgemm( HplColumnMajor, HplNoTrans, HplNoTrans, 2, 2, 2, 2.0, a, 2, b, 2, -1.0, c, 2 ); printf(" [%f,%f]\n", c[0], c[2]); printf("c=[%f,%f]\n", c[1], c[3]); exit(0); return(0); }