Re: Beating C++ std::gcd

To get the "real" (dx, dy), run it as
% ./ts -v 37

A good part of the fun was, to move the circle as little as possible.

-- Ruud


On 2026-08-10 00:29, Ruud H.G. van Tol wrote:
> Also see https://oeis.org/A295344/a295344.svg
> for an alternative presentation.
>
>
> On 2026-08-09 17:11, [email protected] 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)
>