This library contains an R implementation of the S-Plus function interp().
I used Fortran code for cubic spline interpolation from H. Akima available
at http://www.netlib.org/toms .
There are two version, one from 1978 (AMS code 526, used in SPlus 3.x) and a
newer one (AMS 761) from 1996. The original versions are in the directory orig/.
I only had to write a subroutine idptli.f for linear interpolation within
triangles from the delauney triangulation.
I added a function interpp(), which evaluates the interpolated function at
arbitraryly choosen points and generates no regular grid as interp() does.
interp() actually calls interp.new() or interp.old() depending on its arguments,
linear interpolation is done by interp.old(), spline interpolation by interp.new
.
UPDATE (13.12.2004):
Thomas Petzoldt provided an R interface to
Akimas univariate spline interpolation functions (aspline) which has been
included into this library.
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Albrecht Gebhardt email: albrecht.gebhardt@uni-klu.ac.at
Institut fuer Mathematik Tel. : (++43 463) 2700/3118
Universitaet Klagenfurt Fax : (++43 463) 2700/3198
Universitaetsstr. 65-67 WWW : http://www.math.uni-klu.ac.at/~agebhard
A-9020 Klagenfurt, Austria
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