**Next message:**B.H. Chan: "Timed Shutdown (think someone asked)"**Previous message:**Richard Adam: "Intermud"**In reply to:**Kenneth G. Cavness: "RBB: Really Big Bitvectors"**Next in thread:**Graham Gilmore: "Re: RBB: Really Big Bitvectors"**Reply:**Graham Gilmore: "Re: RBB: Really Big Bitvectors"**Reply:**Kenneth G. Cavness: "Re: RBB: Really Big Bitvectors"**Messages sorted by:**[ date ] [ thread ] [ subject ] [ author ]

Kenneth G. Cavness pounded furiously on the keyboard: > 1. Have a 1-3 byte header that somehow denotes what number is what. Even > if you have a 32-bit RBB structure with 126-256+ "bits", it's better than > the original 32-bits you would get otherwise. This doesn't scan. Can you elaborate? > 2. Have the RBB use only prime numbers. There is an easy algorithm to > determine a number's prime eligibility and I'm not sure, but I think there > are more than the usual for each byte, and especially as you get higher > up into the numbers. This is a kewl idea: using Godel numbers for flags! There are 55 primes between 1 and 255. (Someone probably should independantly verify this value.) This would yield a 6:1 increase in the number of flags in a single byte. The number of primes between 1 and 65535 would definitely be way bigger than the sixteen flags that a two byte integer would normally provide. This is a mathematically elegant idea, but I wouldn't use it because it's not as satisfactory as Jaco's bitfield scheme. Bitfield lookups and assignments would be constant time, whereas the Godel number scheme would be O(n). (I, erm, _think_. Anyhoo, this is a best guess upper bound.) Worse yet, any implementations couldn't possibly be as straightforward as ones using bitfields. Oh, there's another problem that makes this scheme intractible: you would have to _multiply_ various primes to yield a single "compressed" value. It's safe to say that it wouldn't take much to overflow a single byte. Still an interesting idea. > 3. Have the RBB use each "bit" in multiples of some number that will allow > you to use the numbers BETWEEN each "bit" as a pointer that this "bit" has > been set. Would require a very elaborate algorithm. Eeek! Yesh. Again, for the sake of understandability, bitfields are still better. Mark -- Mark Coletti | DBA Systems, Inc. Fairfax, VA mcoletti@clark.net | United States Geological Survey http://www.clark.net/pub/mcoletti | Office of Standards & Technology A day without fusion is like a day without sunshine.

**Next message:**B.H. Chan: "Timed Shutdown (think someone asked)"**Previous message:**Richard Adam: "Intermud"**In reply to:**Kenneth G. Cavness: "RBB: Really Big Bitvectors"**Next in thread:**Graham Gilmore: "Re: RBB: Really Big Bitvectors"**Reply:**Graham Gilmore: "Re: RBB: Really Big Bitvectors"**Reply:**Kenneth G. Cavness: "Re: RBB: Really Big Bitvectors"**Messages sorted by:**[ date ] [ thread ] [ subject ] [ author ]

*
This archive was generated by hypermail 2b30
: 12/07/00 PST
*