David Winsemius
On Mar 31, 2009, at 6:09 AM, Stephan Kolassa wrote:
> Hi,
>
> if you are looking for *natural* cubic splines (linear beyond the
> outer knots), you could use rcs() in Frank Harrell's Design package.
>
> HTH,
> Stephan
>
>
> David Winsemius schrieb:
>> If one enters:
>> ??"spline"
>> ... You get quite a few matches. The one in the stats functions
>> that probably answers your specific questions is:
>> "splinefun {stats} R Documentation
>> Interpolating Splines Description
>> Perform cubic (or Hermite) spline interpolation of given data
>> points, returning either a list of points obtained by the
>> interpolation or a function performing the interpolation."
>> "splinefun returns a function with formal arguments x and deriv,
>> the latter defaulting to zero. This function can be used to
>> evaluate the interpolating cubic spline (deriv=0), or its
>> derivatives (deriv=1,2,3) at the points x, where the spline
>> function interpolates the data points originally specified. This is
>> often more useful than spline."
>> Perhaps you need to review from you basic intro material regarding
>> help.search("text") # or
>> ??"text" # possibilities.
>
>
David Winsemius, MD
Heritage Laboratories
West Hartford, CT