On Wed, 12 May 1999, Pierre Abbat wrote:
> Is there a program for factoring numbers up to, say, 2^128 in a reasonable
> time? I tried bc but it doesn't have a factor command, so I wrote a loop and it
> spent all its time outputting.
Get Richard Crandall's giantint package, it contains factor, which will
factor "any size" numbers, using a variety of algorithms.
As for time, I just did a quick test:
echo 123456789012345678901234567890123456789012345678901234 |time ./factor
Sieving...
2 * 73 * 1723 *
Commencing Pollard rho...
..................................................................
..................................................................
..................
Commencing Pollard (p-1)...
..................................................................
Commencing ECM...
Choosing curve 1, with s = 352116908, B = 1000, C = 50000:
..
17108860903
* 28685059068699533197755335074782923141
14.11user 0.01system 0:15.72elapsed 89%CPU
This on a 188MHz Pentium.
You can get giantint from http://www.perfsci.com/
--
Henrik Olsen, Dawn Solutions I/S URL=http://www.iaeste.dk/~henrik/
`Can you count, Banjo?' He looked smug. `Yes, miss. On m'fingers, miss.'
`So you can count up to ...?' Susan prompted.
`Thirteen, miss,' said Banjo proudly. Terry Pratchett, Hogfather
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