Matheval is a library designed for evaluating mathematical expressions. It can parse an expression from clear text and convert into its internal format. My inspiriation for creating matheval comes from such packages as Maple or Mathematica. I wanted to be able to do some of those sorts of things from within Euphoria.
Matheval will do some symbolic evaluation, including simplifying algebraic expressions. Variables can be created and can hold any value, including entire expressions, so some very powerful tasks can be accomplished using matheval. The library has also been designed to be flexible enough to be extended fairly easily.
Matheval can be used as a drop in component for an app that needs to do calculations based on user input, when the calculations themselves are not known until runtime.