1\section{Introduction\label{introduction}}
2\emph{Scatterplot3d} is an \RR\ package for the visualization of
3multivariate data in a three dimensional space.
4\RR\ itself is ``A Language and Environment for Statistical Computing'' (\cite{r-ref}) and a freely
5available statistical software package implementing that language, see
6\url{http://www.R-project.org/}.
7
8Basically \sdd\ generates a scatter plot in the 3D space using a parallel
9projection.  Higher dimensions (fourth, fifth, etc.) of the data can be
10visualized to some extent using, e.g. different colors, symbol types or
11symbol sizes.
12
13The following properties of \sdd\ will be further described and discussed
14in the present paper:
15%
16A plot is generated entirely by using interpreted \RR\ graphics functions,
17so the appearance of the plot is consistent with other \RR\ graphics.
18Such a behavior is % extremely
19important for publications.
20Most features of the \RR\ graphics system can be applied in \sdd , among
21them are vectorizing of colors or plotting symbols and mathematical
22annotation (\cite{murrell00}).
23The latter means whole formulas with e.g.\ greek letters and mathematical
24symbols inside can be added into plots using a \LaTeX\ like syntax.
25%
26\emph{Scatterplot3d} can be easily extended e.g., by adding additional
27points or drawing regression lines or planes into an already generated
28plot (via function closures, see below).
29The package is platform independent and can easily be installed,
30because it only requires an installed version of \RR.
31
32This paper is structured as follows:
33%
34In Section \ref{design} the design of \sdd\ will be described, followed by
35remarks on the extensibility of the function in Section \ref{extend}.
36%
37Some examples (including code and results) on generated and real world data
38are provided in Section \ref{examples}.
39%
40We present other \RR\ related 3D ``tools'' in Section \ref{tools}, followed
41by the conclusion in Section \ref{conclusion}.
42%
43In the Appendix the source code as well as the help page of \sdd\ are
44printed.
45
46\RR\ and \sdd\ are available from \emph{CRAN} (Common \RR\ Archive
47Network), i.e. \url{http://CRAN.R-Project.org } or one of its mirrors.
48
49