|Bill Allombert on Mon, 23 Jan 2017 21:46:29 +0100|
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|Re: Getting a very large polynomial into pari/gp|
On Sun, Jan 01, 2017 at 06:39:03PM +0100, Bill Allombert wrote: > 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). Without a copy of a and b, I cannot ascertain what cause this, but the halfgcd algorithm use much more memory than the normal one. If you like, send me your polynomial and I try that on a machine with 3TB of RAM. Cheers, Bill.