BLAS/SRC/dgemm.f(3)

💖 NAME 💖

BLAS/SRC/dgemm.f — yep, that’s the file, bestie, and it’s living its best life in the Library Functions Manual ✨

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✨ SYNOPSIS ✨

🌸 Functions/Subroutines 🌸

subroutine dgemm (transa, transb, m, n, k, alpha, a, lda, b, ldb, beta,
    c, ldc)
    DGEMM

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🦋 Function/Subroutine Documentation 🦋

subroutine dgemm (character transa, character transb, integer m, integer n,
    integer k, double precision alpha, double precision, dimension(lda,*) a,
    integer lda, double precision, dimension(ldb,*) b, integer ldb, double
    precision beta, double precision, dimension(ldc,*) c, integer ldc)
    DGEMM

✨ Purpose ✨

Okay so DGEMM does 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,

And yeah — 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 💅

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🎀 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, 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, 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, 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 ).

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👑 Author 👑

• Univ. of Tennessee
• Univ. of California Berkeley
• Univ. of Colorado Denver
• NAG Ltd.

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🔥 Further Details 🔥

This one is a 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.

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Definition at line 186 of file dgemm.f.

💜 Author 💜

Generated automatically by Doxygen for LAPACK from the source code.

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