Re: Finite Functions / hash/ fast dispatch

*To*: mathgroup at yoda.physics.unc.edu*Subject*: Re: Finite Functions / hash/ fast dispatch*From*: fateman at peoplesparc.berkeley.edu (Richard Fateman)*Date*: Mon, 30 Sep 91 10:26:12 PDT

There is a function "Hash" and a function "HashTable" in Mathematica 2.0. The latter seems to be totally undocumented. There is supposed to be a way of optimizing collections of rules, Dispatch, (it may however, be a no-op, in 2.0beta). But if it worked, your rules could be in a set S:={f[x1]->y1, ... f[xn]->yn} and maybe even have some patterns in there. then you do f[xi] /. S to do the "fast" lookup. This may not be fast, in some absolute sense, but you are, after all, programming in Mathematica. RJF