|Bill Allombert on Wed, 03 Feb 2010 21:42:58 +0100|
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|Re: ellap hangs on a large-ish prime|
On Tue, Feb 02, 2010 at 01:56:42PM +0100, Andreas Enge wrote: > On Tue, Feb 02, 2010 at 01:05:06PM +0100, Bill Allombert wrote: > > Precisely: Version 2.4.3 include an implementation of SEA which run > > polynomial time, however for a small prime like 2486152157 it still > > use the older algorithm, so this is unrelated. > > In any case, the problem seems to be solved in the current svn. > The original poster's gp script > > E = ellinit([0,0,1,-1,0]); > P = 2486152157; > ellap(E, P) > > returns -13740 in no time. I am not sure the issue is properly addressed in the current SVN: I do not see what prevent points from having 0 coordinates passed to mod2BIL. The function _fix() use lgefint where lg should be used, and I found a case where ellap1 return p+ap (bug #1030), so this bug might still exist in SVN. Probably this thread should be moved to pari-dev now. Cheers, Bill.