Karim BELABAS on Tue, 6 May 2003 17:21:17 +0200 (MEST)

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Re: 64bit bug

On Tue, 6 May 2003, Bill Allombert wrote:
> On Thu, May 01, 2003 at 12:58:24PM -0400, Igor Schein wrote:
>> On Thu, May 01, 2003 at 02:09:26AM +0200, Karim BELABAS wrote:
>>> On Tue, 29 Apr 2003, Karim BELABAS wrote:
>>>> On Mon, 28 Apr 2003, Igor Schein wrote:
>>>>> the following commands gets stuck in an infinite loop:
>>>>> factorpadic(x^3-1,3,10,1);
>>> Committed to CVS. Does it work now ???
>> Yes, it apprears to have been fixed.
>It is also fixed on ia64.


>>> P.S: There are many other things that could be corrected, but
>>> factorpadic(,1) is obsolete, and I don't want to maintain it. Especially
>>> since it can't work
> Well, I feel rather distressing our infrastructure do not allow us to
> support both Round 2 and Round 4.

It would. Round 2 has essentially the same interface as Round 4.
But factorpadic(, 1) does not implement Round 2, it (ab)uses the splitting of
primes ( primedec ).

The main problem is that padicff was written together with the original
primedec [ which was a few orders of magnitude slower than the current one ],
that the old code was monolithic and completely undocumented.

I've completely rewritten primedec some time ago, and the current code
[ cf http://www.math.u-psud.fr/~belabas/pub/index.html#modf ] is modular.

Unfortunately, it also heavily uses the official specification of the routine
[ input is 'nf' + 'p', return 'pr' ], where 'nf' is a rather complicated
structure containing a number of "expensive" data [ e.g multiplication table ].

It would be relatively easy to separate the functionality requested by
padicff() out of primedec(). I did most of it some time ago: the resulting
code was much slower than Round 4 (which was slower at the time than it is
now). I did not bother.


Karim Belabas                     Tel: (+33) (0)1 69 15 57 48
Dép. de Mathématiques, Bât. 425   Fax: (+33) (0)1 69 15 60 19
Université Paris-Sud              http://www.math.u-psud.fr/~belabas/
F-91405 Orsay (France)            http://www.parigp-home.de/  [PARI/GP]