static inline int

cheb_eval_mode_e(const cheb_series * cs,

                 const double x,

                 gsl_mode_t mode,

                 gsl_sf_result * result)

{

  int j;

  double d  = 0.0;

  double dd = 0.0;

  double y  = (2.*x - cs->a - cs->b) / (cs->b - cs->a);

  double y2 = 2.0 * y;

  int eval_order;

  if(GSL_MODE_PREC(mode) == GSL_PREC_DOUBLE)

    eval_order = cs->order;

  else

    eval_order = cs->order_sp;

  for(j = eval_order; j>=1; j--) {

    double temp = d;

    d = y2*d - dd + cs->c[j];

    dd = temp;

  }

  result->val = y*d - dd + 0.5 * cs->c[0];

  result->err = GSL_DBL_EPSILON * fabs(result->val) + fabs(cs->c[eval_order]);

  return GSL_SUCCESS;

}