1DGEMM(1) BLAS routine DGEMM(1)
2
6 DGEMM - one of the matrix-matrix operations C := alpha*op( A )*op( B
7 ) + 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 Level 3 Blas routine.
122 -- Written on 8-February-1989. Jack Dongarra, Argonne National
124 Laboratory. Iain Duff, AERE Harwell. Jeremy Du Croz, Numerical
125 Algorithms Group Ltd. Sven Hammarling, Numerical Algorithms
126 Group Ltd.
127BLAS routine November 2006 DGEMM(1)