NAXPERT: A prototype expert system for numerical software The prototype expert system described in this paper works for a mathematical library of 50 routines for the IBM personal computer. It provides assistance to two types of user of the library: a user who does not know which routine to use may consult NAXPERT which will try to find a suitable routine: a user who knows which routine to use may request that NAXPERT constructs a skeleton FORTRAN program for using the routine. par As a typical expert system NAXPERT contains a user interface, a knowledge base, a knowledge engine and an explanation facility. The implementation language is Prolog. Knowledge is represented by keywords, routine specifications and rules that describe relations between keywords. The knowledge base, the knowledge engine and all NAXPERT facilities are presented. Examples are given which show the selection of a routine, a routine description, a FORTRAN skeleton and the explanation facility. par The authors are pointing out that “NAXPERT is a prototype expert system which is under development and many improvements are clearly possible and desirable”. Related work on assistance to users of numerical software is summarized.