[R] R-functions in C-Code

[Roger Bivand]

On Mon, 31 Oct 2005, Olaf Schenk wrote:

> Dear R users,
> 
> I would like to use several R functions from a C-code and I have read
> the "Introduction to the .C Interface to R". Unfortunately, my shared
> library with the C-code works only in cases where I use R-routines that
> are defined Rmath.h, eg.

Please see Chapter 5, the R API, and check which C functions are in the 
API. dnorm() is - though you've been lucky (or unlucky) because the 
arguments appear to agree. So your example seems to work.

However, the mean() function is an R function, not in the R API. For
executing R code from C, see Chapter 4, section 9, "Evaluating R
expressions from C".

> 
> *************************************
> less test.c:
> #include <R.h>
> #include <Rinternals.h>
> #include <Rmath.h>
> void test(int *nrows, SEXP init,SEXP fac1, SEXP typeordi, SEXP bgratio)
> {
>         double sum = dnorm(1.0/1, 0, 1, 0);
> }
> 
> Compiling and building shared library:
>    gcc -I/usr/lib64/R/include -fPIC -O2 -c test.o test.c
>    gcc -shared -L/usr/local/lib -o test.so test.o -L/usr/lib64/R/lib -lR
> Calling R and loading test.so works fine:
>    >dyn.load("test.so")
>    >
> *************************************
> 
> Now, I would like to use other R functions e.g. the mean function from
> the base package:
> 
> *************************************
> #include <R.h>
> #include <Rinternals.h>
> #include <Rmath.h>
> void test(int *nrows, SEXP init,SEXP fac1, SEXP typeordi, SEXP bgratio)
> {
>         double sum = mean(1.0);
> }
> 
> Compiling and building shared library:
>    gcc -I/usr/lib64/R/include -fPIC -O2 -c test.o test.c
>    gcc -shared -L/usr/local/lib -o test.so test.o -L/usr/lib64/R/lib -lR
> 
> Calling R and loading test.so results in an error:
>    > dyn.load("test.so")
>    Error in dyn.load(x, as.logical(local), as.logical(now)) :
>         unable to load shared library '/home/obc/test.so':
> 
> 
> Any hint is welcome.
> 
> Olaf Schenk
> 
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-- 
Roger Bivand
Economic Geography Section, Department of Economics, Norwegian School of
Economics and Business Administration, Helleveien 30, N-5045 Bergen,
Norway. voice: +47 55 95 93 55; fax +47 55 95 95 43
e-mail: Roger.Bivand at nhh.no