— Function: int gsl_bspline_knots (const gsl_vector * breakpts, gsl_bspline_workspace * w)

This function computes the knots associated with the given breakpoints and stores them internally in w->knots.

— Function: int gsl_bspline_knots_uniform (const double a, const double b, gsl_bspline_workspace * w)

This function assumes uniformly spaced breakpoints on [a,b] and constructs the corresponding knot vector using the previously specified nbreak parameter. The knots are stored in w->knots.