.TH DGEMM 1 "November 2006" "BLAS routine" "BLAS routine" .SH NAME DGEMM - one of the matrix-matrix operations C := alpha*op( A )*op( B ) + beta*C, .SH SYNOPSIS .TP 67 SUBROUTINE DGEMM(TRANSA,TRANSB,M,N,K,ALPHA,A,LDA,B,LDB,BETA,C,LDC) .TP 67 .ti +4 DOUBLE PRECISION ALPHA,BETA .TP 67 .ti +4 INTEGER K,LDA,LDB,LDC,M,N .TP 67 .ti +4 CHARACTER TRANSA,TRANSB .TP 67 .ti +4 DOUBLE PRECISION A(LDA,*),B(LDB,*),C(LDC,*) .SH PURPOSE DGEMM performs one of the matrix-matrix operations where op( X ) is one of .br op( X ) = X or op( X ) = X\(aq, .br 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. .SH ARGUMENTS TRANSA - CHARACTER*1. On entry, TRANSA specifies the form of op( A ) to be used in the matrix multiplication as follows: TRANSA = \(aqN\(aq or \(aqn\(aq, op( A ) = A. TRANSA = \(aqT\(aq or \(aqt\(aq, op( A ) = A\(aq. TRANSA = \(aqC\(aq or \(aqc\(aq, op( A ) = A\(aq. Unchanged on exit. TRANSB - CHARACTER*1. On entry, TRANSB specifies the form of op( B ) to be used in the matrix multiplication as follows: TRANSB = \(aqN\(aq or \(aqn\(aq, op( B ) = B. TRANSB = \(aqT\(aq or \(aqt\(aq, op( B ) = B\(aq. TRANSB = \(aqC\(aq or \(aqc\(aq, op( B ) = B\(aq. Unchanged on exit. .TP 7 M - 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. Unchanged on exit. .TP 7 N - 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. Unchanged on exit. .TP 7 K - 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. Unchanged on exit. .TP 7 ALPHA - DOUBLE PRECISION. On entry, ALPHA specifies the scalar alpha. Unchanged on exit. .TP 7 A - DOUBLE PRECISION array of DIMENSION ( LDA, ka ), where ka is k when TRANSA = \(aqN\(aq or \(aqn\(aq, and is m otherwise. Before entry with TRANSA = \(aqN\(aq or \(aqn\(aq, 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. Unchanged on exit. .TP 7 LDA - INTEGER. On entry, LDA specifies the first dimension of A as declared in the calling (sub) program. When TRANSA = \(aqN\(aq or \(aqn\(aq then LDA must be at least max( 1, m ), otherwise LDA must be at least max( 1, k ). Unchanged on exit. .TP 7 B - DOUBLE PRECISION array of DIMENSION ( LDB, kb ), where kb is n when TRANSB = \(aqN\(aq or \(aqn\(aq, and is k otherwise. Before entry with TRANSB = \(aqN\(aq or \(aqn\(aq, 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. Unchanged on exit. .TP 7 LDB - INTEGER. On entry, LDB specifies the first dimension of B as declared in the calling (sub) program. When TRANSB = \(aqN\(aq or \(aqn\(aq then LDB must be at least max( 1, k ), otherwise LDB must be at least max( 1, n ). Unchanged on exit. .TP 7 BETA - DOUBLE PRECISION. On entry, BETA specifies the scalar beta. When BETA is supplied as zero then C need not be set on input. Unchanged on exit. .TP 7 C - 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 ). .TP 7 LDC - 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 ). Unchanged on exit. 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. .. External Functions .. .. .. External Subroutines .. ..