📄 dgemm.c
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#include "f2c.h"
#include "netlib.h"
/* Subroutine */ void dgemm_(transa, transb, m, n, k, alpha, a, lda, b, ldb, beta, c, ldc)
const char *transa, *transb;
const integer *m, *n, *k;
doublereal *alpha, *a;
const integer *lda;
doublereal *b;
const integer *ldb;
doublereal *beta, *c;
const integer *ldc;
{
/* System generated locals */
integer a_dim1, a_offset, b_dim1, b_offset, c_dim1, c_offset, i__1, i__2, i__3;
/* Local variables */
static integer info;
static logical nota, notb;
static doublereal temp;
static integer i, j, l /*, ncola */;
static integer nrowa, nrowb;
/* Purpose */
/* ======= */
/* */
/* DGEMM performs 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', */
/* */
/* 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. */
/* */
/* Parameters */
/* ========== */
/* */
/* TRANSA - 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'. */
/* */
/* TRANSA = 'C' or 'c', op( A ) = A'. */
/* */
/* 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 = 'N' or 'n', op( B ) = B. */
/* */
/* TRANSB = 'T' or 't', op( B ) = B'. */
/* */
/* TRANSB = 'C' or 'c', op( B ) = B'. */
/* */
/* Unchanged on exit. */
/* */
/* 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. */
/* */
/* 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. */
/* */
/* 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. */
/* */
/* ALPHA - DOUBLE PRECISION. */
/* On entry, ALPHA specifies the scalar alpha. */
/* Unchanged on exit. */
/* */
/* A - DOUBLE PRECISION array of 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. */
/* Unchanged on exit. */
/* */
/* LDA - 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 ). */
/* Unchanged on exit. */
/* */
/* B - DOUBLE PRECISION array of 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. */
/* Unchanged on exit. */
/* */
/* LDB - 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 ). */
/* Unchanged on exit. */
/* */
/* 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. */
/* */
/* 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 ). */
/* */
/* 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. */
/* Parameter adjustments */
a_dim1 = *lda;
a_offset = 1 + a_dim1 * 1;
a -= a_offset;
b_dim1 = *ldb;
b_offset = 1 + b_dim1 * 1;
b -= b_offset;
c_dim1 = *ldc;
c_offset = 1 + c_dim1 * 1;
c -= c_offset;
/* Set NOTA and NOTB as true if A and B respectively are not */
/* transposed and set NROWA, NCOLA and NROWB as the number of rows */
/* and columns of A and the number of rows of B respectively. */
nota = lsame_(transa, "N");
notb = lsame_(transb, "N");
if (nota) {
nrowa = *m;
/* ncola = *k; */
} else {
nrowa = *k;
/* ncola = *m; */
}
if (notb) {
nrowb = *k;
} else {
nrowb = *n;
}
/* Test the input parameters. */
info = 0;
if (! nota && ! lsame_(transa, "C") && ! lsame_(transa, "T")) {
info = 1;
} else if (!notb && !lsame_(transb, "C") && !lsame_(transb, "T")) {
info = 2;
} else if (*m < 0) {
info = 3;
} else if (*n < 0) {
info = 4;
} else if (*k < 0) {
info = 5;
} else if (*lda < max(1,nrowa)) {
info = 8;
} else if (*ldb < max(1,nrowb)) {
info = 10;
} else if (*ldc < max(1,*m)) {
info = 13;
}
if (info != 0) {
xerbla_("DGEMM ", &info);
return;
}
/* Quick return if possible. */
if (*m == 0 || *n == 0 || (*alpha * *k == 0 && *beta == 1.) ) {
return;
}
/* And if alpha.eq.zero. */
if (*alpha == 0.) {
if (*beta == 0.) {
i__1 = *n;
for (j = 1; j <= i__1; ++j) {
i__2 = *m;
for (i = 1; i <= i__2; ++i) {
c[i + j * c_dim1] = 0.;
}
}
} else {
i__1 = *n;
for (j = 1; j <= i__1; ++j) {
i__2 = *m;
for (i = 1; i <= i__2; ++i) {
c[i + j * c_dim1] *= *beta;
}
}
}
return;
}
/* Start the operations. */
if (notb) {
if (nota) {
/* Form C := alpha*A*B + beta*C. */
i__1 = *n;
for (j = 1; j <= i__1; ++j) {
if (*beta == 0.) {
i__2 = *m;
for (i = 1; i <= i__2; ++i) {
c[i + j * c_dim1] = 0.;
}
} else if (*beta != 1.) {
i__2 = *m;
for (i = 1; i <= i__2; ++i) {
c[i + j * c_dim1] *= *beta;
}
}
i__2 = *k;
for (l = 1; l <= i__2; ++l) {
if (b[l + j * b_dim1] != 0.) {
temp = *alpha * b[l + j * b_dim1];
i__3 = *m;
for (i = 1; i <= i__3; ++i) {
c[i + j * c_dim1] += temp * a[i + l * a_dim1];
}
}
}
}
} else {
/* Form C := alpha*A'*B + beta*C */
i__1 = *n;
for (j = 1; j <= i__1; ++j) {
i__2 = *m;
for (i = 1; i <= i__2; ++i) {
temp = 0.;
i__3 = *k;
for (l = 1; l <= i__3; ++l) {
temp += a[l + i * a_dim1] * b[l + j * b_dim1];
}
if (*beta == 0.) {
c[i + j * c_dim1] = *alpha * temp;
} else {
c[i + j * c_dim1] = *alpha * temp + *beta * c[i + j * c_dim1];
}
}
}
}
} else {
if (nota) {
/* Form C := alpha*A*B' + beta*C */
i__1 = *n;
for (j = 1; j <= i__1; ++j) {
if (*beta == 0.) {
i__2 = *m;
for (i = 1; i <= i__2; ++i) {
c[i + j * c_dim1] = 0.;
}
} else if (*beta != 1.) {
i__2 = *m;
for (i = 1; i <= i__2; ++i) {
c[i + j * c_dim1] *= *beta;
}
}
i__2 = *k;
for (l = 1; l <= i__2; ++l) {
if (b[j + l * b_dim1] != 0.) {
temp = *alpha * b[j + l * b_dim1];
i__3 = *m;
for (i = 1; i <= i__3; ++i) {
c[i + j * c_dim1] += temp * a[i + l * a_dim1];
}
}
}
}
} else {
/* Form C := alpha*A'*B' + beta*C */
i__1 = *n;
for (j = 1; j <= i__1; ++j) {
i__2 = *m;
for (i = 1; i <= i__2; ++i) {
temp = 0.;
i__3 = *k;
for (l = 1; l <= i__3; ++l) {
temp += a[l + i * a_dim1] * b[j + l * b_dim1];
}
if (*beta == 0.) {
c[i + j * c_dim1] = *alpha * temp;
} else {
c[i + j * c_dim1] = *alpha * temp + *beta * c[i + j * c_dim1];
}
}
}
}
}
} /* dgemm_ */
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