Statistical Software
The latest versions of SAS and S-PLUS (S+) can be purchased from Technology Support Services. Each of these applications are renewed annually, so the price that you are paying is to "lease" the software for 1 year. A student version of S+ can be purchased by students who are currently enrolled in a Statistics class. This version costs $5.00, and can be purchased from the Statistics Office (Kidder 44).
A very good (free/open source) statistical application, which is very similar to S+, is R. This software is available from the R project website, and is available for a variety of UNIX platforms, Windows, and MacOS. This manual (PDF download) is a good place to start learning about R.
Other applications which can be obtained from Technology Support
Services include Statgraphics, Maple, Mathematica, SPSS and Stata.
A "leased" copy of Matlab is available for purchase from COSINe. Also check their website to learn about applications available on Unix/Linux servers that you can use by simply logging into the proper server and running the software from there.
