On 2 Oct 2006, at 15:35, [EMAIL PROTECTED] wrote:
On Mon, 02 Oct 2006 21:28:56 Nacho <[EMAIL PROTECTED]> wrote: > >Cazor Denis wrote: >> Hello, >> >> It is generally admitted than observable Universe >> has about 10^80 particules. >> So, a computer with the size of observable universe >> can make a sieve with numbers of 80 decimal digits >> maximum. >> >> Denis Cazor > >I don't think so, because you only store the prime numbers, not every >number. This will make room for more prime numbers. So we return to our >original problem. How many primes are less than a given n? > >Regards. No. Denis is using each particle in the universe as a SINGLE BINARY BIT to represent each integer on the number line, and setting those bits to on or off to represent prime or not-prime. It's a Sieve of Erathostene because he lines up all the ones (initial state) and then turns off every other bit above 2 to factor out the 2's, every third above 3 etc. If he stored just the prime numbers themselves then he would need 267 bits per number to store them in (~10**80) and he would just have a list of primes, not a sieve. -Kary _______________________________________________ Prime mailing list [email protected] http://hogranch.com/mailman/listinfo/prime
