|Bill Allombert on Fri, 27 Jan 2017 11:17:54 +0100|
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|Re: Getting a very large polynomial into pari/gp|
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). After investigating with Neill we found this was due to a problem with GMP 6.0.0 with LLP64 system when using more than 2GB of memory, so I have rebuild the Pari installer with GMP 6.1.2 which fix this problem: <http://pari.math.u-bordeaux.fr/pub/pari/windows/snapshots/Pari64-2-9-1_gmp612.exe> Please test that it does not introduce other issues. If all go well, I will use this GMP build for the next stable releases. Cheers, Bill.