[R] How to get the penalty matrix for natural cubic spline?

[Frank E Harrell Jr]

Yan Li wrote:
> Hi, all
> 
> I am trying to get the basis matrix and penalty matrix for natural
> cubic splines. In the "splines" package of R,"ns" can
> generate the B-spline basis matrix for a natural cubic spline. How can
> I get the basis matrix and penalty matrix for natural cubic
> spline.
> 
> Thanks a lot!
> 
> Lee

In usual practice the natural cubic spline does not use penalization.
Frank

-- 
Frank E Harrell Jr   Professor and Chairman        School of Medicine
                      Department of Biostatistics   Vanderbilt University