Geoff I didn't check the primes rules when I made this function but it works! I just assumed finding any factors would be quick enough for the small range of numbers RR can compute natively (2^48 I think was the max). I'll adapt it!
http://www.utm.edu/research/primes/prove/prove2_1.html says <quote> Home > Primality Proving > Chapter Two > Small Primes For finding all the small primes, say all those less than 10,000,000,000; one of the most efficient ways is by using the Sieve of Eratosthenes (ca 240 BC): "Make a list of all the integers less than or equal to n (greater than one) and strike out the multiples of all primes less than or equal to the square root of n, then the numbers that are left are the primes. (See also our glossary page.)" <no more quote> Thanks for bringing that up! I think I found an 11 billion digits prime using my law of primes! I got a pc trying to crunch it since 5 months! ;) I may need to hack something myself after all to test it! As a quantum geek would say: That's odd! X > -----Original Message----- > From: [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED] On Behalf Of Geoff Canyon > Sent: Thursday, December 09, 2004 16:19 > To: Discussions on Metacard > Subject: Re: is prime > > On Dec 8, 2004, at 10:39 AM, MisterX wrote: > > > put (x div 2) into xfactors > > I haven't read through the rest carefully, but shouldn't this > be trunc(sqrt(x))? You don't need to check for factors beyond > the square root. > > regards, > > Geoff Canyon > [EMAIL PROTECTED] > > _______________________________________________ > metacard mailing list > [EMAIL PROTECTED] > http://lists.runrev.com/mailman/listinfo/metacard > _______________________________________________ metacard mailing list [EMAIL PROTECTED] http://lists.runrev.com/mailman/listinfo/metacard
