extern "C" for C++

[Vanroose <vanroose at ruca dot ua dot ac dot be>]

Dear  GSL-users,

        As discussed  in  the november archives of this mailing list  I have to include  a  'extern "C" ' before I include the GSL headerfile when I want to use a gsl-function in C++.
 
       So I added to  my code

#ifdef __cplusplus
extern "C" {
#endif
#include <gsl_sf_result.h>
#include <gsl_sf_coulomb.h>
#include <gsl_sf_laguerre.h>
#include <gsl_sf_gamma.h>
#include <gsl_sf_erf.h>
#include <gsl_integration.h>
#ifdef  __cplusplus
}
#endif

 
        This results into problems  in   math.h   with function overloading

gcc -c -fpic  potential.cc -I/xopt/python1.5/include/python1.5 -I/home/edp/vanroose/archief/vanroose/Python-1.5.2/Numerical-14/Include/ -I/home/edp/vanroose/include/gsl/
In file included from /home/edp/vanroose/include/gsl/gsl_math.h:3,
                 from /home/edp/vanroose/include/gsl/gsl_integration.h:4,
                 from potential.cc:9:
/xopt/gnu/lib/gcc-lib/hppa1.1-hp-hpux10.20/2.95.1/include/math.h: In function `double pow(double, int)':
/xopt/gnu/lib/gcc-lib/hppa1.1-hp-hpux10.20/2.95.1/include/math.h:74: declaration of C function `double pow(double, int)' conflicts with
/xopt/gnu/lib/gcc-lib/hppa1.1-hp-hpux10.20/2.95.1/include/math.h:71: previous declaration `double pow(double, double)' here
/xopt/gnu/lib/gcc-lib/hppa1.1-hp-hpux10.20/2.95.1/include/math.h: In function `double pow(double, int)':
/xopt/gnu/lib/gcc-lib/hppa1.1-hp-hpux10.20/2.95.1/include/math.h:75: warning: `double' used for argument 2 of `pow(double, int)'
make: *** [potentialC] Error 1
 

            When  I look to  the math.h code that the compiler refers to

#ifdef _INCLUDE_HPUX_SOURCE
     extern double log2(double);
#endif
     extern double modf(double, double *);
     extern double pow(double, double);
#    ifdef __cplusplus
     }
     inline double pow(double __d,int __expon) {
  return pow(__d,(double)__expon);
     }
     extern "C" {
#else
#    endif

             It seems  that when math.h is included  the __cplusplus variable is still set but due to the extern "C" derictive the code is compiled as C. Or am I wrong??