Re: Beating C++ std::gcd

["Ruud H.G. van Tol" <rvtol@isolution.nl>]

Hello Hermann,

Also see https://oeis.org/A295344/a295344.svg
for an alternative presentation.

-- Ruud



On 2026-08-09 17:11, hermann@stamm-wilbrandt.de wrote:
> Interesting.
>
> I did let it run and stopped execution after output of the a(37) 
> coordinate line after 6.5h runtime on AMD 9950X CPU.
>
> I did want to look at it, and recently gemini did good jobs for me for 
> similar tasks with python scripts and matplotlib.
>
> This time I asked for HTML page with JavaScript and SVG:
> https://share.gemini.google/HWG4yAgIxW74
>
> Impressive what beautiful result a 544 character prompt instruction 
> plus the computed log data returned:
> https://stamm-wilbrandt.de/A295344.gp.html
>
> Now it is a pleasure to step through the different circle radius 
> solutions, there is a movie mode as well.
>
> Regards,
>
> Hermann.
>
> On 2026-08-09 05:48, Ruud H.G. van Tol wrote:
> > On 2026-08-08 13:51, Ruud H.G. van Tol wrote:
> > > In a project I'm working on, I measured that about 25% of its 
> > > runtime was spent in gcd.
> > > The program runs with 10 threads, on a MacBook M1 Max.
> > >
> > > On my clang, std::gcd came out as the best suited implementation.
> > > Then I started looking for more speed, and tried a lookup table for 
> > > smaller values.
> > > And that made it 20% faster!
> > >   gcd(a, b); 0 <= a <= 511; 0 <= b <= 1023.
> >
> > It is used in this project:
> >
> > https://oeis.org/A295344/a295344.gp.txt (GP code)
> > https://oeis.org/A295344/a295344_1.cpp.txt (C++ code)
> > https://oeis.org/A295344/a295344_7.txt (example of output)