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On Wed, 28 Oct 1998, Jay Glascoe wrote: > yes, in almost all cases. it's faster, e.g. to check whether two symbols > are eq? because then, in the C code, you're comparing two long's, > whereas testing two SCM numbers requires that you do two SCM_INUM()'s > > #define SCM_INUM(x) (((x)>>1)>>1) which takes a fraction of a nano-second. > the problem is that a full size long won't fit into a SCM INUM. I'm > currently masking (and'ing) my hash with 2,097,157 which does fit, but > obviously won't work work for extremely huge tables (>2,000,000 entries). 536,870,912 = 2 ^ 29 - 1 fits alright, and 536,870,909 = 536,870,912 - 3 is prime (bonus!). Anyone needing a hash table with more than half a billion entries (perhaps to keep track of each individual McDonald's hamburger sold over the course of one week ;) would probably be better off with some kind of database instead. From now on all my hash values will be INUM's. Jay jglascoe@jay.giss.nasa.gov