|Kaz Kobara on Sun, 02 Feb 2014 00:46:58 +0100|
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|RE: Your help needed|
> By curiosity, how did you compute factor(N) ? We are interested in only small h=N/n and prime order n. So we accept only N s.t. N/h is a prime number for small h. This can be checked using isprime(N/h) == 1 for small h. Kaz > -----Original Message----- > From: Bill Allombert [mailto:Bill.Allombert@math.u-bordeaux1.fr] > Sent: Sunday, February 2, 2014 4:44 AM > To: Kaz Kobara > Cc: firstname.lastname@example.org > Subject: Re: Your help needed > > On Thu, Jan 30, 2014 at 07:46:36AM +0900, Kaz Kobara wrote: > > Dear Bill and all, > > > > > Not unless you know the factorisation of the order of the elliptic > > > curve, or some similar useful information > > > > Thank you for this information. > > > > That's why the manual of ellorder() > > > http://pari.math.u-bordeaux.fr/dochtml/html/Functions_related_to_ell > ip > > tic_cu > > rves.html > > suggests to supply o of > > > > ? N = p+1-ellap(E,p); o = [N, factor(N)]; > > > > This solved our problem. Thank you very much. > > By curiosity, how did you compute factor(N) ? > > Cheers, > Bill.