static inline int cheb_eval_e(const cheb_series * cs, const double x, gsl_cdf_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; }