The theoretical and practical treatment of partial differential equations is a highly complex domain of mathematics with a multitude of possible phenomena. Consequently, the design of optimal numerical methods is also difficult, and the efficient implementation of such methods is an even more challenging problem. Therefore, originally, software in this domain could handle only very special problems well and was not applicable to other situations. But this changed in the last decade, when more and more software packages appeared, claiming to be multi-purpose tools for solving partial differential equations.
FEMLISP is such a multi-purpose tool. But in contrast to other PDE solvers which are mostly written using machine-oriented languages like Fortran, C, or C++, it is written in Lisp, which is a language long known from research in Artificial Intelligence (AI).