" J is a functional shareware programming language available via anonymous ftp at watserv1.waterloo.edu.
Features include list-at-a-time processing, arrays of arrays, complex numbers, special features for multiplying polynomials, manipulating sets and generating permutations. Although it provides support for numerical modeling, it is not a numerical modeling package. It is a general purpose programming language.
J was designed and developed by Ken Iverson and Roger Hui. It is similar to the language APL, departing from APL in using using the ASCII alphabet exclusively, but employing a spelling scheme that retains the advantages of the special alphabet required by APL. It has added features and control structures that extend its power beyond standard APL."