The Open Source version of the REDUCE algebra system was registered on SourceForge.net on Dec 18, 2008.
REDUCE is a system for doing scalar, vector and matrix algebra by computer, which also supports arbitrary precision numerical approximation and interfaces to gnuplot to provide graphics. It can be used interactively for simple calculations (as illustrated in the screenshot above) but also provides a full programming language, with a syntax similar to other modern programming languages.
REDUCE has a long and distinguished place in the history of computer algebra systems (see the bibliography). Other systems that address some of the same issues but sometimes with rather different emphasis are Axiom, Macsyma (Maxima), Maple and Mathematica.
REDUCE is implemented in Lisp (as are Axiom and Macsyma), but this is completely hidden from the casual user. REDUCE primarily runs on either Portable Standard Lisp (PSL) or Codemist Standard Lisp (CSL), both of which are included in the SourceForge distribution. PSL is long-established and compiles to machine code, whereas CSL is newer and compiles to byte code. Hence, PSL may be faster but CSL may be available on a wider range of platforms.
Tony Hearn, who is the main and original author of this software, writes:
In 1963, I began work on a software system that would in time evolve into REDUCE. By 1968, copies had been made available to various researchers throughout the world. Forty years later, there is still an active community of users. In order to encourage further development, I have decided to make the software freely available under a modified BSD license.