Yacas (Yet Another Computer Algebra System) is a small and highly flexible
general-purpose Computer Algebra System (CAS). The syntax uses an
infix-operator grammar parser. The distribution contains a small library
of mathematical functions, but its real strength is in the language in which
you can easily write your own symbolic manipulation algorithms. The core engine
supports arbitrary precision arithmetic and is able to execute symbolic
manipulations on various mathematical objects by following user-defined rules.
For detailed information on yacas features and usage, see
http://www.yacas.org .