Re: Platform-dependent LLL reduction (qflll)

[mancha <mancha1@zoho.com>]

On Mon, May 10, 2021 at 11:00:39PM +0200, Bill Allombert wrote:
> On Mon, May 10, 2021 at 06:22:45PM +0000, mancha wrote:
> > Hi.
> > 
> > While helping someone with their knapsack-crypto project on
> > freenode's ##math channel, we discovered that LLL-reduced bases
> > generated by 32-bit and 64-bit versions of PARI/GP 2.13.1 don't
> > always match. Is this expected/anticipated behavior?
> 
> Yes. This is due to our implementation of fplll with PARI t_REAL.
> The initial working precision is 32bit on 32bit and 64bit on 64bit,
> so we get different result. In libpari it is possible to force
> 64bit in both case.

Aha, mystery solved. Thank you.