static inline int

cheb_eval_e(const cheb_series * cs,

            const double x,

            gsl_sf_result * result)

{

  int j;

  double d  = 0.0;

  double dd = 0.0;

  double y  = (2.0*x - cs->a - cs->b) / (cs->b - cs->a);

  double y2 = 2.0 * y;

  double e = 0.0;

  for(j = cs->order; j>=1; j--) {

    double temp = d;

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

    e += fabs(y2*temp) + fabs(dd) + fabs(cs->c[j]);

    dd = temp;

  }

  { 

    double temp = d;

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

    e += fabs(y*temp) + fabs(dd) + 0.5 * fabs(cs->c[0]);

  }

  result->val = d;

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

  return GSL_SUCCESS;

}