|
2007-04-19, 22:35
|
#1 |
|
Apr 2007
3 Posts |
using libecm from python
Hello,
I am writing a wrapper for ecm using python and pyrex. I have successfully wrapped the ecm_factor method defined in ecm.h but am a bit confused about the factors it sometimes finds. If I call ecm_factor(f, n, B1, NULL), the factor it finds is sometimes equal to n. I thought it was supposed to return you a nontrivial factor. Cheers, Yi |
|
|
|
2007-04-20, 08:31
|
#2 |
"Nancy"
Aug 2002
Alexandria
1001101000112 Posts |
It depends on the parameters. Bad sigma values can cause the trivial factor N to be found, specifically sigma=0,1,2,3 and 5, afaik. Also, if all prime factors in N are relatively small and your B1 value is high enough, ECM can find all factors simultaneously and hence return N as the factor.
Alex |
|
|
|
|
2007-04-22, 00:14
|
#3 |
|
Apr 2007
38 Posts |
Aha, I see. Thanks for your clear explanation.
Yi |
|
|
|
 |
| Thread Tools | |
Similar Threads
|
||||
| Thread | Thread Starter | Forum | Replies | Last Post |
| PHP vs. Python vs. C (all with GMP) | daxmick | Programming | 2 | 2014-02-10 01:45 |
| Python... | Xyzzy | Programming | 20 | 2009-09-08 15:51 |
| Is libecm thread-safe? | frmky | GMP-ECM | 5 | 2009-02-28 16:08 |
| Can't bind libecm.a with C++ files | poire | GMP-ECM | 2 | 2006-03-21 14:41 |
| Help w/ python. | a216vcti | Programming | 7 | 2005-10-30 00:37 |
