/// Exponential integrals E_n. double expint_En(int n, double x) { gsl_sf_result result; int stat = gsl_sf_expint_En_e(n, x, &result); if (stat != GSL_SUCCESS) { std::ostringstream msg("Error in expint_En:"); msg << " n=" << n << " x=" << x; throw std::runtime_error(msg.str()); } else return result.val; }
double gsl_sf_expint_En(const int n, const double x) { EVAL_RESULT(gsl_sf_expint_En_e(n, x, &result)); }