Hello: I have a question about spline: ns (or bs) in R (library: splines). What's the exact analytic form of the B splines generated by ns (or bs)? I need to calculate the penalty (square of second order derivative) of the basis functions. Is there any shortcut or I need to program myself? thanks, Shuangge Ma ********************* Department of Statistics Phone: 608-263-4782(O) University of Wisconsin--Madison