int gsl_sf_dilog_e(double x,double* result);
double gsl_sf_dilog(double x);
int gsl_sf_complex_dilog_xy_e(double x,double y,double* result_re,double* result_im);
int gsl_sf_complex_dilog_e(double r,double theta,double* result_re,double* result_im);
int gsl_sf_complex_spence_xy_e(double x,double y,double* real_sp,double* imag_sp);