Re: Problem with Flx_ffisom function

[Jean-Pierre Flori <flori@enst.fr>]

Isn't "f" a polynomial over Z?

2014-12-05 17:17 GMT+01:00 Karim Belabas <Karim.Belabas@math.u-bordeaux.fr>:
> Hi,
>
> * Jean-Pierre Flori [2014-12-05 17:03]:
>> The following programs errors out claiming that the produced
>> irreducible polynomial is not anymore
>> (***   not an irreducible polynomial in FpX_ffintersect):
>>
>> #include <stdlib.h>
>> #include <stdio.h>
>> #include <time.h>
>>
>> #include <pari/pari.h>
>>
>> int main (int argc, char **argv)
>> {
>>         int i;
>>         unsigned long l;
>>         long n, v;
>>         GEN p, f, r;
>>
>>         pari_init(1<<30, 1UL<<20);
>>
>>         v = 0L;
>>
>>         l = unextprime(1UL<<20);
>>         p = stoi(l);
>>         n = 179L;
>>         f = init_Fq(p, n, v);
>>         i = Flx_is_irred(ZX_to_Flx(f, l), l);
>                            ^^^^^^^^^^^^^^^
>>         pari_printf("%d\n", i);
>>
>>         t = clock();
>           ^^^^^^^^^^^^  [ I'd declare t ... ]
>> /*
>>         The following works fine.
>> */
>>         r = FpX_ffisom(f, f, p);
>>         pari_printf("%Ps\n", r);
>> /*
>>         This errors out
>> */
>>         r = Flx_ffisom(f, f, l);
>
> I'd apply Flx_ffisom to a Flx, as correctly done above.
> Not to the original FpX.
>
> After
>
>   f = ZX_to_Flx(f,l)
>
> (and declaring clock_t t) the code above works fine.
>
>> Thanks in advance for the support!
>
> You're welcome :-)
>
>     K.B.
> --
> Karim Belabas, IMB (UMR 5251)  Tel: (+33) (0)5 40 00 26 17
> Universite de Bordeaux         Fax: (+33) (0)5 40 00 69 50
> 351, cours de la Liberation    http://www.math.u-bordeaux1.fr/~kbelabas/
> F-33405 Talence (France)       http://pari.math.u-bordeaux1.fr/  [PARI/GP]
> `
>



-- 
Jean-Pierre Flori