Re: Getting a very large polynomial into pari/gp

[Bill Allombert <Bill.Allombert@math.u-bordeaux.fr>]

On Sun, Jan 01, 2017 at 03:47:11AM +0000, Neill Clift wrote:
> On 12/31/2016 9:05 AM, Bill Allombert wrote:
> > The libpari library provides a set of functions to deal with polynomials
> > over F_p that implement the half-GCD algorithm but they are not directly
> > available in GP.
> >
> > Try:
> > install("FpX_gcd","GGG")
> > p = 2^64-59;
> > a = Pol(read("a.gp"));
> > b = Pol(read("b.gp"));
> > FpX_gcd(a,b,p)
> >
> > and actually since p is less than 2^64 there is another function that
> > use a more compact representation of polynomials (Vecsmall), but the
> > above function will do the conversions for you.
> > Read about FpX, FpX_gcd, Flx and Flx_gcd in the documentation.
> While the other gcd ran overnight this one failed in an hour.
> 
> (18:03) gp > FpX_gcd(a,b,p)
>    ***   at top-level: FpX_gcd(a,b,p)
>    ***                 ^--------------
>    *** FpX_gcd: not enough memory
> (19:08) gp >
> 
> This seems to be different from the stack size messages I have got 
> (stack size set to 64G).
> > If you use Windows make sure to use the installer and ot the stand-alone
> > binary. Unfortunately install() does not work with the stand-alone
> > binary.
> I believe I used the installer as I have a desktop icon that's a 
> shortcut to pari/gp and it shows installed in control panel.
> >
> > For this kind of computation, you should consider using the PARI library
> > directly.
> That was my initial thought as well but my first try at getting the code 
> to compile with just the Pari header included gave me errors:
> 
> 1>../src/kernel/none/divll_pre.h(37): error C2275: 'pari_ulong': illegal 
> use of this type as an expression
> 1>  c:\program files (x86)\pari64-2-9-1\include\pari\parigen.h(17): 
> note: see declaration of 'pari_ulong'
> 1>../src/kernel/none/divll_pre.h(37): error C2146: syntax error: missing 
> ')' before identifier '__arg'

You should try this on Linux with gcc.
On win64, only mingw64 is supported and even this is haskish, see
config/convertllp64 in the PARi distribution.

Cheers,
Bill.