| 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; |
| } |