R

R is a programming language and environment for statistical computing.

The R environment and its source code are freely available under the GNU GPL license; precompiled binaries exist for Microsoft Windows, Unix, and Mac OS platforms. R uses a command line interface, but several graphical user interfaces are also available.

R is highly extensible: users can submit libraries ("packages") implementing a set of functions, usually for a specific area of their expertise/research. R community maintains several centralized repositories that make hundreds of such packages readily available to all users over the Internet (see http://www.r-project.org). Many of these packages cater specifically to highly specialized audiences with particular data analysis needs.

For more information, see R Integration with STATISTICA.