XLISP-STAT is a statistical environment based on a dialect of the Lisp
language called XLISP.  To facilitate statistical computations, standard Lisp
functions for addition, logarithms, etc., have been modified to operate on
lists and arrays of numbers, and a number of basic statistical functions have
been added.

WWW: http://www.stat.uiowa.edu/~luke/xls/xlsinfo/xlsinfo.html