There is a valuable website http://www.alpertron.com.ar/ECM.HTM that factors integers. The computation is done by a Java applet on your machine so the performance is not affected by user load on the site.
----- Original Message ----- From: Jonathan Lettvin <[email protected]> Date: Friday, April 24, 2009 6:19 Subject: Re: [Jprogramming] table of primes to 1,000,000,000 or more To: Programming forum <[email protected]> > Being all practical (I apologize), would it not be nice to have > a godaddy > server on a domain called "isprime.info" with some ULNT > (unpleasantly large > number of Terabytes), where each bit was mapped to a cardinal > from 1 to > ULNT*8e12, serving all who care for Brobdignagian primes which > returns a > minimalist formatted response to a request like: > > http://www.isprime.info?number=17 > > which would return something like: > > <html><body>YY</body></html> > > The server would perform two tasks, calculating more primes and > serving them > from storage that grows as the calculation of primes continues > until whoever > is funding it says "no-one could possibly need a prime higher > than that". > > Better yet, modify the source of ping or other lightweight > protocol listener > on isprime.info to deliver back a response containing the two proposed > binaries called "calculated" and "primeness". There > would be only three > possible responses NN, YN, YY. > > How about a fragment of code on sourceforge that implements a > socket to > isprime.info that does the equivalent fetch? > > This would not be hard to implement and might prevent > consumption of > important thinking time for the surprisingly large subpopulation of > mathematicians who recalculate the already calculated series of known > contiguous primes. > > Of course, it might annoy cryptographers, but is that a bad thing? > > On Fri, Apr 24, 2009 at 7:53 AM, Don Guinn > <[email protected]> wrote: > > > Make that visible universe. > > > > On Thu, Apr 23, 2009 at 6:13 PM, Roger Hui > <[email protected]> wrote: > > > > > The radius of the universe in meters is: > > > 15e9 years * 365.2425 days/year * 24 hours/day * > > > 3600 seconds/hour * 3e8 meters/second > > > > > > ] r=: */ 15e9 365.2425 3600 24 3e8 > > > 1.42006e26 > > > > > > Its volume in cubic meters is: > > > o. 4r3 * r^3 > > > 1.19953e79 > > > > > > The minimum size of an atom is a Bohr radius sphere: > > > o. 4r3 * 5.3e_11 ^ 3 > > > 6.23615e_31 > > > > > > The number of atoms is therefore bounded by the > > > former divided by the latter: > > > (o. 4r3 * r^3) % (o. 4r3 * 5.3e_11^3) > > > 1.92351e109 > > > > > > That is, if the entire universe is packed with atoms, > > > there'd be no more than 2e109 of them. > > > > > > > > > > > > ----- Original Message ----- > > > From: [email protected] > > > Date: Thursday, April 23, 2009 13:59 > > > Subject: Re: [Jprogramming] table of primes to 1,000,000,000 > or more > > > To: Programming forum <[email protected]> > > > > > > > I believe the estimate of 10^100 atoms is actually hydrogen > > > > atoms. > > > > > > > > Anyhow, I got my estimate from wikipedia.com. > > > > > > > > > > > > ----- Original Message Follows ----- > > > > From: Zsbán Ambrus <[email protected]> > > > > To: Programming forum <[email protected]> > > > > Subject: Re: [Jprogramming] table of primes to 1,000,000,000 > > > > or more > > > > Date: Sun, 19 Apr 2009 11:29:10 +0200 > > > > > > > > >On Sat, Apr 18, 2009 at 10:10 PM, > > > > >> <[email protected]> wrote: If there are ~ > > > > >10^100 atoms in the universe, > > > > > > > > > >I think that's an underestimate, there are actually between > > > > >10^200 and 10^300 atoms in the universe I believe. ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
