This library contains an R implementation of some triangulation routines. It is based on Fortran code from R. J. Renka in the ACM Collected Algorithms archive under http://www.netlib.org/toms/751 R. J. Renka (1996). Algorithm 751: TRIPACK: a constrained two-dimensional {Delaunay} triangulation package. ACM Transactions on Mathematical Software. 22, 1-8. I added the Fortran files inhull.f and voronoi.f wich implements additional subroutines for determination of convex hulls and voronoi mosaics. Currently the library contains the following R functions which provide access to the Fortran subroutines of TRIPACK and implements new objects for triangu- lations and voronoi mosaics: add.constraint convex.hull identify.tri in.convex.hull neighbours on.convex.hull outer.convhull plot.tri plot.voronoi print.summary.tri print.summary.voronoi print.tri print.tri summary.tri summary.voronoi tri tri.find tri.mesh triangles voronoi voronoi.mosaic The help pages are based on the Fortran comments. This library was intended by the akima library, which also contains some (but not all) of the TRIPACK functions. Currently plots of voronoi mosaics may fail (due to numerical problems) if the corresponding triangulation contains very small triangles at the boundary. ------------------------------------------------------------------ Albrecht Gebhardt email: albrecht.gebhardt@uni-klu.ac.at Institut fuer Mathematik Tel. : (++43 463) 2700/837 Universitaet Klagenfurt Fax : (++43 463) 2700/834 Villacher Str. 161 A-9020 Klagenfurt, Austria ------------------------------------------------------------------ The abstract of the original article at ACM follows: ############################################################################## TRIPACK is a Fortran 77 software package that employs an incremental algorithm to construct a constrained Delaunay triangulation of a set of points in the plane (nodes). The triangulation covers the convex hull of the nodes but may include polygonal constraint regions whose triangles are distinguishable from those in the remainder of the triangulation. This effectively allows for a nonconvex or multiply connected triangulation (the complement of the union of constraint regions) while retaining the efficiency of searching and updating a convex triangulation. The package provides a wide range of capabilities including an efficient means of updating the triangulation with nodal additions or deletions. For N nodes, the storage requirement is 13N integer storage locations in addition to the 2N nodal coordinates. ############################################################################## Meanwhile I got also feedback from the original author, especially regarding the copyright situation: ############################################################################## Albrecht, I took a quick look at your addition of TRIPACK to R, and it looks very nice. I'm very pleased that you found my code useful. There is an updated version of TRIPACK available from netlib and described in Remark on Algorithm 751, ACM TOMS, Vol 25, No. 1, March 1999, pp 97-98. It adds some capabilities and correcta a couple of possible bugs. A LaTeX file is attached. I cannot give you a definitive answer to the copyright question. The question was still being debated when I was an ACM editor, and I have not carefully read the current policy. There may be a requirement that the source code retain the ACM copyright notice or something like that. I suggest that you pose the question to the current CALGO EIC, Tim Hopkins (t.r.hopkins@ukc.ac.uk). Feel free to contact me if you encounter problems in the code. Robert ##############################################################################