Hi,
I was wondering if I could use the matprod function from array.c in my own C
routine. I tried the following as a test
/* my_matprod.c */
# include <Rinternals.h> /* for REAL, SEXP etc */
# include <R_ext/Applic.h> /* array.c says need for dgemm */
/* following copied from array.c */
static void matprod(double *x, int nrx, int ncx,
double *y, int nry, int ncy, double *z)
{
char *transa = "N", *transb = "N";
int i, j, k;
double one = 1.0, zero = 0.0, sum;
Rboolean have_na = FALSE;
if (nrx > 0 && ncx > 0 && nry > 0 && ncy > 0) {
/* Don't trust the BLAS to handle NA/NaNs correctly: PR#4582
* The test is only O(n) here
*/
for (i = 0; i < nrx*ncx; i++)
if (ISNAN(x[i])) {have_na = TRUE; break;}
if (!have_na)
for (i = 0; i < nry*ncy; i++)
if (ISNAN(y[i])) {have_na = TRUE; break;}
if (have_na) {
for (i = 0; i < nrx; i++)
for (k = 0; k < ncy; k++) {
sum = 0.0;
for (j = 0; j < ncx; j++)
sum += x[i + j * nrx] * y[j + k * nry];
z[i + k * nrx] = sum;
}
} else
F77_CALL(dgemm)(transa, transb, &nrx, &ncy, &ncx, &one,
x, &nrx, y, &nry, &zero, z, &nrx);
} else /* zero-extent operations should return zeroes */
for(i = 0; i < nrx*ncy; i++) z[i] = 0;
}
/* test function: matrix multiplication of nr by nc matrix with nc-vector */
SEXP my_matprod(SEXP M, SEXP v, SEXP nr, SEXP nc) {
R_len_t nrm = INTEGER(nr)[0], ncm = INTEGER(nc)[0];
SEXP ans;
PROTECT(ans = allocMatrix(REALSXP, nrm, 1));
matprod(REAL(M), nrm, ncm,
REAL(v), ncm, 1, REAL(ans));
UNPROTECT(1);
return(ans);
}
When I try to make the DLL I get the following
D:\C_routines>RCMD SHLIB my_matprod.c
making my_matprod.d from my_matprod.c
gcc -IC:/R/tex/R-2.2.0/include -Wall -O2 -c my_matprod.c -o my_matprod.o
ar cr my_matprod.a my_matprod.o
ranlib my_matprod.a
gcc --shared -s -o my_matprod.dll my_matprod.def my_matprod.a -LC:/R/tex/R-2.
2.0/src/gnuwin32 -lg2c -lR
my_matprod.a(my_matprod.o)(.text+0x19a):my_matprod.c: undefined reference to `dg
emm_'
collect2: ld returned 1 exit status
make: *** [my_matprod.dll] Error 1
I'm using Windows XP and I'm using the MinGW gcc. It works fine if I comment
out the Fortran call so that the method for have_na is always used.
Do I need to include another header file to use dgemm? Is there a better way to
use matprod than just to copy the code?
Any help appreciated,
Heather
Dr H Turner
Research Assistant
Dept. of Statistics
The University of Warwick
Coventry
CV4 7AL
Tel: 024 76575870
Url: www.warwick.ac.uk/go/heatherturner
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