The NATS project (National Activity to Test Software) was a joint undertaking by the Atomic Energy Commission and the National Science Foundation to explore the problems of creating, testing, certifying, disseminating, and maintaining high quality mathematical software for a variety of different computers. Intrinsic to this study was the creation of two software packages. The first is EISPACK, a now widely distributed collection of matrix eigensystem subroutines which are nearly machine independent. The second package, FUNPACK, is by contrast a small collection of highly machine dependent, special function subroutines. This latter package is certified for use on only three different lines of computers and is not intended to be easily transportable to other machines.