| Add functions: | |
| gsl_bspline_eval_deriv (see pppack bsplvd) to compute B-spline derivatives | |
| gsl_bspline_smooth to fit smoothing splines to data more efficiently | |
| than the standard least squares inversion (see pppack l2appr and | |
| smooth.spline() from GNU R) | |
| + any other useful functions from pppack |