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.