Computation of a Cubic B-Spline Basis and Its Derivatives //
Computation of a cubic B-spline basis for arbitrary knots. It
also provides the 1st and 2nd derivatives, as well as the
integral of the basis elements. It is used by the author to fit
penalized B-spline models, see e.g. Jullion, A. and Lambert, P.
(2006) doi:10.1016/j.csda.2006.09.027, Lambert, P. and
Eilers, P.H.C. (2009) doi:10.1016/j.csda.2008.11.022 and, more
recently, Lambert, P. (2021) doi:10.1016/j.csda.2021.107250. It
is inspired by the algorithm developed by de Boor, C. (1977)
doi:10.1137/0714026.