Re: Segmentation Fault in PARI library related to factoru_pow()

[Karim Belabas <Karim.Belabas@math.u-bordeaux.fr>]

* Max Alekseyev [2017-11-29 20:40]:
> It was surely my oversight in assuming the wrong type of factoru_pow()'s
> result components. However, I got confused by the "bug in PARI/GP" and
> "please report" message. This made me think that I may be facing a bug
> rather than an error in my program.

Almost all error messages were designed assuming the user was actually
running 'gp' and not a custom program. :-) 

And when you get a SEGV in 'gp', it's always a bug worth reporting.

> Btw, speaking about factorization - is there any benefit in
> using  factor_pn_1(p,1) to factor p-1 for prime p as compared to
> factor(p-1)?

None whatsoever. That function is a big help when factoring p^n - 1
for large n [ which arises as the cardinal of the multiplicative group of
finite fields ] since it quickly finds special (Aurifeuillean) factors
of Phi_d(p) for suitable d satisfying p | d | n.

Thus, for d = 1, there are no "special" factors...

Cheers,

    K.B.
--
Karim Belabas, IMB (UMR 5251)  Tel: (+33) (0)5 40 00 26 17
Universite de Bordeaux         Fax: (+33) (0)5 40 00 21 23
351, cours de la Liberation    http://www.math.u-bordeaux.fr/~kbelabas/
F-33405 Talence (France)       http://pari.math.u-bordeaux.fr/  [PARI/GP]
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