DGEMM (3) Linux Manual Page

dgemm.f –

Synopsis

Functions/Subroutines

subroutine dgemm (TRANSA, TRANSB, M, N, K, ALPHA, A, LDA, B, LDB, BETA, C, LDC)
DGEMM

Function/Subroutine Documentation

subroutine dgemm (characterTRANSA, characterTRANSB, integerM, integerN, integerK, double precisionALPHA, double precision, dimension(lda,*)A, integerLDA, double precision, dimension(ldb,*)B, integerLDB, double precisionBETA, double precision, dimension(ldc,*)C, integerLDC)

DGEMM Purpose:

 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.

 

Parameters:

TRANSA

 TRANSA is CHARACTER*1

 On entry, TRANSA specifies the form of op( A ) to be used in

 the matrix multiplication as follows:

 TRANSA = ‘N’ or ‘n’, op( A ) = A.

 TRANSA = ‘T’ or ‘t’, op( A ) = A**T.

 TRANSA = ‘C’ or ‘c’, op( A ) = A**T.

TRANSB

 TRANSB is CHARACTER*1

 On entry, TRANSB specifies the form of op( B ) to be used in

 the matrix multiplication as follows:

 TRANSB = ‘N’ or ‘n’, op( B ) = B.

 TRANSB = ‘T’ or ‘t’, op( B ) = B**T.

 TRANSB = ‘C’ or ‘c’, op( B ) = B**T.

M

 M is INTEGER

 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

 N is INTEGER

 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

 K is INTEGER

 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 at least zero.

ALPHA

 ALPHA is DOUBLE PRECISION.

 On entry, ALPHA specifies the scalar alpha.

A

 A is DOUBLE PRECISION array of DIMENSION ( LDA, ka ), where ka is

 k when TRANSA = ‘N’ or ‘n’, and is m otherwise.

 Before entry with TRANSA = ‘N’ or ‘n’, 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

 LDA is INTEGER

 On entry, LDA specifies the first dimension of A as declared

 in the calling (sub) program. When TRANSA = ‘N’ or ‘n’ then

 LDA must be at least max( 1, m ), otherwise LDA must be at

 least max( 1, k ).

B

 B is DOUBLE PRECISION array of DIMENSION ( LDB, kb ), where kb is

 n when TRANSB = ‘N’ or ‘n’, and is k otherwise.

 Before entry with TRANSB = ‘N’ or ‘n’, 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

 LDB is INTEGER

 On entry, LDB specifies the first dimension of B as declared

 in the calling (sub) program. When TRANSB = ‘N’ or ‘n’ then

 LDB must be at least max( 1, k ), otherwise LDB must be at

 least max( 1, n ).

BETA

 BETA is DOUBLE PRECISION.

 On entry, BETA specifies the scalar beta. When BETA is

 supplied as zero then C need not be set on input.

C

 C is DOUBLE PRECISION 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

 LDC is INTEGER

 On entry, LDC specifies the first dimension of C as declared

 in the calling (sub) program. LDC must be at least

 max( 1, m ).

 

Author:

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

Date:

November 2011

Further Details:

 Level 3 Blas routine.

 — Written on 8-February-1989.

 Jack Dongarra, Argonne National Laboratory.

 Iain Duff, AERE Harwell.

 Jeremy Du Croz, Numerical Algorithms Group Ltd.

 Sven Hammarling, Numerical Algorithms Group Ltd.

 

Definition at line 188 of file dgemm.f.

Author

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