1DGEMM(1) BLAS routine DGEMM(1)
2
6 DGEMM - performs one of the matrix-matrix operations C := alpha*op( A
7 )*op( B ) + beta*C,
8
10 SUBROUTINE DGEMM(TRANSA,TRANSB,M,N,K,ALPHA,A,LDA,B,LDB,BETA,C,LDC)
11 DOUBLE PRE‐
13 CI‐
14 SION
15 ALPHA,BETA
16 INTEGER K,LDA,LDB,LDC,M,N
18 CHARACTER TRANSA,TRANSB
20 DOUBLE PRE‐
22 CI‐
23 SION
24 A(LDA,*),B(LDB,*),C(LDC,*)
25
27 DGEMM performs one of the matrix-matrix operations
28 where op( X ) is one of
30 op( X ) = X or op( X ) = X',
32 alpha and beta are scalars, and A, B and C are matrices, with op( A )
34 an m by k matrix, op( B ) a k by n matrix and C an m by n matrix.
35
38 TRANSA - CHARACTER*1. On entry, TRANSA specifies the form of op( A )
39 to be used in the matrix multiplication as follows:
40 TRANSA = 'N' or 'n', op( A ) = A.
42 TRANSA = 'T' or 't', op( A ) = A'.
44 TRANSA = 'C' or 'c', op( A ) = A'.
46 Unchanged on exit.
48 TRANSB - CHARACTER*1. On entry, TRANSB specifies the form of op( B )
50 to be used in the matrix multiplication as follows:
51 TRANSB = 'N' or 'n', op( B ) = B.
53 TRANSB = 'T' or 't', op( B ) = B'.
55 TRANSB = 'C' or 'c', op( B ) = B'.
57 Unchanged on exit.
59 M - INTEGER.
61 On entry, M specifies the number of rows of the matrix op(
62 A ) and of the matrix C. M must be at least zero.
63 Unchanged on exit.
64 N - INTEGER.
66 On entry, N specifies the number of columns of the matrix op(
67 B ) and the number of columns of the matrix C. N must be at
68 least zero. Unchanged on exit.
69 K - INTEGER.
71 On entry, K specifies the number of columns of the matrix op(
72 A ) and the number of rows of the matrix op( B ). K must be at
73 least zero. Unchanged on exit.
74 ALPHA - DOUBLE PRECISION.
76 On entry, ALPHA specifies the scalar alpha. Unchanged on exit.
77 A - DOUBLE PRECISION array of DIMENSION ( LDA, ka ), where ka is
79 k when TRANSA = 'N' or 'n', and is m otherwise. Before
80 entry with TRANSA = 'N' or 'n', the leading m by k part of
81 the array A must contain the matrix A, otherwise the leading
82 k by m part of the array A must contain the matrix A.
83 Unchanged on exit.
84 LDA - INTEGER.
86 On entry, LDA specifies the first dimension of A as declared in
87 the calling (sub) program. When TRANSA = 'N' or 'n' then LDA
88 must be at least max( 1, m ), otherwise LDA must be at least
89 max( 1, k ). Unchanged on exit.
90 B - DOUBLE PRECISION array of DIMENSION ( LDB, kb ), where kb is
92 n when TRANSB = 'N' or 'n', and is k otherwise. Before
93 entry with TRANSB = 'N' or 'n', the leading k by n part of
94 the array B must contain the matrix B, otherwise the leading
95 n by k part of the array B must contain the matrix B.
96 Unchanged on exit.
97 LDB - INTEGER.
99 On entry, LDB specifies the first dimension of B as declared in
100 the calling (sub) program. When TRANSB = 'N' or 'n' then LDB
101 must be at least max( 1, k ), otherwise LDB must be at least
102 max( 1, n ). Unchanged on exit.
103 BETA - DOUBLE PRECISION.
105 On entry, BETA specifies the scalar beta. When BETA is
106 supplied as zero then C need not be set on input. Unchanged on
107 exit.
108 C - DOUBLE PRECISION array of DIMENSION ( LDC, n ).
110 Before entry, the leading m by n part of the array C must
111 contain the matrix C, except when beta is zero, in which
112 case C need not be set on entry. On exit, the array C is
113 overwritten by the m by n matrix ( alpha*op( A )*op( B ) +
114 beta*C ).
115 LDC - INTEGER.
117 On entry, LDC specifies the first dimension of C as declared in
118 the calling (sub) program. LDC must be at least max( 1,
119 m ). Unchanged on exit.
120
122 Level 3 Blas routine.
123 -- Written on 8-February-1989.
125 Jack Dongarra, Argonne National Laboratory.
126 Iain Duff, AERE Harwell.
127 Jeremy Du Croz, Numerical Algorithms Group Ltd.
128 Sven Hammarling, Numerical Algorithms Group Ltd.
129BLAS routine November 2008 DGEMM(1)