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Technical Reference: Base Operating System and Extensions , Volume 2
Performs matrixmatrix operations
on general matrices.
BLAS Library
(libblas.a)
SUBROUTINE SGEMM(TRANSA, TRANSB, M, N, K,
ALPHA, A, LDA, B, LDB, BETA, C, LDC)
CHARACTER*1 TRANSA, TRANSB
INTEGER M, N, K, LDA, LDB, LDC
REAL ALPHA, BETA
REAL A(LDA,*), B(LDB,*), C(LDC,*)
SUBROUTINE DGEMM(TRANSA, TRANSB, M, N, K,
ALPHA, A, LDA, B, LDB, BETA, C, LDC)
CHARACTER*1 TRANSA,TRANSB
INTEGER M,N,K,LDA,LDB,LDC
DOUBLE PRECISION ALPHA,BETA
DOUBLE PRECISION A(LDA,*), B(LDB,*), C(LDC,*)
SUBROUTINE CGEMM(TRANSA, TRANSB, M, N, K,
ALPHA, A, LDA, B, LDB, BETA, C, LDC)
CHARACTER*1 TRANSA,TRANSB
INTEGER M,N,K,LDA,LDB,LDC
COMPLEX ALPHA,BETA
COMPLEX A(LDA,*), B(LDB,*), C(LDC,*)
SUBROUTINE ZGEMM(TRANSA, TRANSB, M, N, K,
ALPHA, A, LDA, B, LDB, BETA, C, LDC)
CHARACTER*1 TRANSA,TRANSB
INTEGER M,N,K,LDA,LDB,LDC
COMPLEX*16 ALPHA,BETA
COMPLEX*16 A(LDA,*), B(LDB,*), C(LDC,*)
The SGEMM,
DGEMM, CGEMM, or ZGEMM subroutine performs
one of the matrixmatrix operations:
C := alpha
* op( A ) * op( B ) + beta
* C
where op( X ) is one of op( X ) =
X or op( X ) = X',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.
TRANSA
 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'
 TRANSA =
'C' or 'c'
 op( A ) = A'
Unchanged on exit.

TRANSB
 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'
 TRANSB =
'C' or 'c'
 op( B ) = B'
Unchanged on exit.

M
 On entry, M specifies the number of rows of the matrix op(
A ) and of the matrix C; M must be at least 0;
unchanged on exit.

N
 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 0; unchanged on exit.

K
 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 0; unchanged on exit.

ALPHA
 On entry, ALPHA specifies the scalar alpha; unchanged on
exit.

A
 An array of dimension ( LDA, KA ), where
KA is K when TRANSA = 'N' or
'n', and is M otherwise; on 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; unchanged on
exit.

LDA
 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
); unchanged on exit.

B
 An array of dimension ( LDB, KB ) where
KB is N when TRANSB = 'N' or
'n', and is K otherwise; on 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; unchanged on
exit.

LDB
 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
); unchanged on exit.

BETA
 On entry, BETA specifies the scalar beta. When
BETA is supplied as 0 then C need not be set on
input; unchanged on exit.

C
 An array of dimension ( LDC, N ); on entry,
the leading M by N part of the array C must
contain the matrix C, except when beta is 0, 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
 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.

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