Karim Belabas on Sun, 09 Dec 2007 18:25:13 +0100 |
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Re: FFELT: how to recover the field? |
* Jeroen Demeyer [2007-12-09 16:31]: > Hello list, > > Given a FFELT x in characteristic p, I would like to compute a p-th root of > x. What's wrong with sqrtn(x,p) ? > The most obvious way to do this is to compute x^(p^(n-1)), where p^n is > the cardinality of the field. However, how can I recover p x.p > and n given only the FFELT? Obviously, it suffices to get the > polynomial defining the finite field (i.e. the argument given to > ffgen()). I tried x.mod, but that doesn't work. It doesn't seem to be possible currently (only x.p and x.pol work). I'll add x.mod to the allowed member functions Cheers, K.B. -- Karim Belabas Tel: (+33) (0)5 40 00 26 17 Universite Bordeaux 1 Fax: (+33) (0)5 40 00 69 50 351, cours de la Liberation http://www.math.u-bordeaux.fr/~belabas/ F-33405 Talence (France) http://pari.math.u-bordeaux.fr/ [PARI/GP] `