Re: Faster digits and fromdigits in base 2^k, and FlxqM_mul_Kronecker

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

On Thu, Oct 08, 2015 at 05:51:07PM +0200, Peter Bruin wrote:
> Hi Bill,
> >> My motivation for this was mostly to speed up multiplication of matrices
> >> over non-prime finite fields of small characteristic (FlxqM).  I am
> >> attaching a second patch (FlxqM_mul_Kronecker.patch) that enhances
> >> Kronecker multiplication for FlxqM to use the above functions for
> >> packing into and unpacking from integer matrices in cases where it
> >> allows us to pack the entries in fewer words per entry than the
> >> (half-)word-aligned packing that is used now.
> >
> > Hello Peter,
> >
> > Thanks for your patch!
> >
> > Is that method applicable to ZX_mul and Flx_mul ?
> > (What about ZX_eval2BILspec/Z_mod2BIL_ZX (and
> > Flx_mulspec_mulii_inflate/Z_mod2BIL_Flx)) ?
> 
> In principle it is, but it is harder to make it pay off because the
> overhead remains non-negligible.  I spent some time trying to apply this
> method to Flx_mul; so far I haven't managed to get a systematic speed-up
> over the existing code, but I am still optimistic that some improvement
> may be possible.  As for ZX_mul, I haven't looked at that yet.

I am working on it for Flx_mul/Flx_sqr. There still some tuning to do.

Thanks again for this patch!

Cheers,
Bill