JEP is a Java API for parsing and evaluating mathematical expressions. With this library, you can allow your users to enter an arbitrary formula as a string and instantly evaluate it. JEP supports user defined variables, constants, and functions. A number of common mathematical functions and constants are included.
A faster evaluator was added. A configurable parser was added. High precision calculation using BigDecimal was implemented. A new component architecture is used. Much more was done.
URL: Singular Systems - JEP - Java Math Expression Parser