R devel - Jun 2015 - Problem with shared library and lapack under windows

Hi all,

I have a C function, say Cfun, that calls Lapack's DGEMM routine and I need
to create a shared library to use Cfun inside R. The C file is the following

#include<stdio.h>
#include<R.h>
#include<R_ext/Lapack.h>


void Cfun(double *res, double *X, int *n, int *q)
{
	char *ptr_TRANSA, TRANSA='T', *ptr_TRANSB, TRANSB='N';
	ptr_TRANSA=&TRANSA;
	ptr_TRANSB=&TRANSB;
	double *ptr_ALPHA, ALPHA=1.0, *ptr_BETA, BETA=0.0;
	ptr_ALPHA=&ALPHA;
	ptr_BETA=&BETA;

	dgemm_(ptr_TRANSA, ptr_TRANSB, q, q, n, ptr_ALPHA, X, n, X, n, ptr_BETA,
res, q);
}

In Ubuntu I have no problem in compiling:  R CMD SHLIB -llapack myfile.c.
However, under Windows the -llapack flag is not recognised and I am able to
get the code compiled only if I build an R package with the suitable
Makevars file options: PKG_LIBS=$(LAPACK_LIBS) $(FLIBS). Is there a way to
get the .dll without resorting to build a package?

Thanks in advance,

N. Lunardon





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> On 03-06-2015, at 09:48, bstr <nicola.lunardon at hotmail.it> wrote:
> 
> Hi all,
> 
> I have a C function, say Cfun, that calls Lapack's DGEMM routine and I
need
> to create a shared library to use Cfun inside R. The C file is the
following
> 
> #include<stdio.h>
> #include<R.h>
> #include<R_ext/Lapack.h>
> 
> 
> void Cfun(double *res, double *X, int *n, int *q)
> {
> 	char *ptr_TRANSA, TRANSA='T', *ptr_TRANSB, TRANSB='N';
> 	ptr_TRANSA=&TRANSA;
> 	ptr_TRANSB=&TRANSB;
> 	double *ptr_ALPHA, ALPHA=1.0, *ptr_BETA, BETA=0.0;
> 	ptr_ALPHA=&ALPHA;
> 	ptr_BETA=&BETA;
> 
> 	dgemm_(ptr_TRANSA, ptr_TRANSB, q, q, n, ptr_ALPHA, X, n, X, n, ptr_BETA,
> res, q);
> }
> 
> In Ubuntu I have no problem in compiling:  R CMD SHLIB -llapack myfile.c.
> However, under Windows the -llapack flag is not recognised and I am able to
> get the code compiled only if I build an R package with the suitable
> Makevars file options: PKG_LIBS=$(LAPACK_LIBS) $(FLIBS). Is there a way to
> get the .dll without resorting to build a package?
> 
I wouldn?t exactly know since I?m not using Windows.

Try this:

R CMD config LAPACK_LIBS

to see the command line options needed.

And why are you using dgemm_?
Use the F77_CALL macro provided by R; you?ll be less system dependent that way.

Berend

On 03/06/2015 08:48, bstr wrote:
> Hi all,
>
> I have a C function, say Cfun, that calls Lapack's DGEMM routine and I
need
> to create a shared library to use Cfun inside R. The C file is the
following
>
> #include<stdio.h>
> #include<R.h>
> #include<R_ext/Lapack.h>
>
>
> void Cfun(double *res, double *X, int *n, int *q)
> {
> 	char *ptr_TRANSA, TRANSA='T', *ptr_TRANSB, TRANSB='N';
> 	ptr_TRANSA=&TRANSA;
> 	ptr_TRANSB=&TRANSB;
> 	double *ptr_ALPHA, ALPHA=1.0, *ptr_BETA, BETA=0.0;
> 	ptr_ALPHA=&ALPHA;
> 	ptr_BETA=&BETA;
>
> 	dgemm_(ptr_TRANSA, ptr_TRANSB, q, q, n, ptr_ALPHA, X, n, X, n, ptr_BETA,
> res, q);
> }
>
> In Ubuntu I have no problem in compiling:  R CMD SHLIB -llapack myfile.c.
> However, under Windows the -llapack flag is not recognised and I am able to
> get the code compiled only if I build an R package with the suitable
> Makevars file options: PKG_LIBS=$(LAPACK_LIBS) $(FLIBS). Is there a way to
> get the .dll without resorting to build a package?
SHLIB reads a Makevars file ....  The manual says so right at the top of 
the section 
http://cran.r-project.org/doc/manuals/r-release/R-exts.html#Using-Makevars .
>
> Thanks in advance,
>
> N. Lunardon

-- 
Brian D. Ripley,                  ripley at stats.ox.ac.uk
Emeritus Professor of Applied Statistics, University of Oxford
1 South Parks Road, Oxford OX1 3TG, UK