I hope that someone reading this list can offer some suggestions on how I can 
incorporate external C libraries in C functions that I want to call from R.  I 
have gone through all of the documentation, help files and mailing list 
archives and have not been able to find a satisfactory solution.

I have constructed a simple example of the problem, since my "real" program is 
much more complex and would bog down discussion.  Suppose I want to compute the 
value of a Gaussian hypergeometric function using the function in the GSL 
library.  My C code is:

        #include </usr/include/gsl/gsl_sf_hyperg.h>

        void gslTestHG (double *a, double *b, double *c, double *x, double *val 
) {
                *val = gsl_sf_hyperg_2F1(*a,*b,*c,*x); 
        }

I compile this code (successfully) using R CMD SHLIB gslTest.c and get the 
following result

        -bash-3.00$ R CMD SHLIB RgslTest.c
        gcc -I/usr/lib64/R/include -I/usr/lib64/R/include  -I/usr/local/include 
  -fpic  -O2 -g -c RgslTest.c -o RgslTest.o
        gcc -shared -L/usr/local/lib64 -o RgslTest.so RgslTest.o   
-L/usr/lib64/R/lib -lR

Next, I try to load the shared object into R using dyn.load("RgslTest.so") and 
get the following error in R:

        > dyn.load("RgslTest.so")
        Error in dyn.load(x, as.logical(local), as.logical(now)) : 
        unable to load shared library 
'/mnt/san2/braunm/winshare/braunm/Cpractice/RgslTest.so':
         /mnt/san2/braunm/winshare/braunm/Cpractice/RgslTest.so: undefined 
symbol: gsl_sf_hyperg_2F1

I am certain that the file path in the #include statement is correct.  It looks 
like R can't find the gsl function in the C program, even though the compiler 
did.

I would greatly appreciate any help you can provide.  Many thanks in advance.

Best wishes,

Michael

------------------------------------------
Michael Braun
Assistant Professor of Marketing
MIT Sloan School of Management
38 Memorial Drive, E56-329
Cambridge, MA 02139
[EMAIL PROTECTED]
(617) 253-3436

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