[bug #68459] Optimize "isprimelarge.cc" on systems with native 128-bit arithmetics

"Dmitri A. Sergatskov" <[email protected]> Thu, 18 Jun 2026 16:46:24 -0400 (EDT)

Newsgroups	gmane.comp.gnu.octave.bugs
Message-ID	<[email protected]>

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Follow-up Comment #1, bug #68459 (group octave):

CSET is attached. 
(file bug68459_isprimelarge_20260618_100.cset)
Some benchmarks on Intel Ultra9 285 (Fedora linux; gcc 16.1.1)
Before:

octave:1> n = uint64 (2305843009213690000) + uint64 (1:1e6);
octave:2> tic; isprime (n); toc
Elapsed time is 2.20224 seconds.
octave:3> n = uint64 (1084978968791);
octave:4> tic; m = factor (n); toc
Elapsed time is 0.104714 seconds.
octave:5> 


After:

octave:1> n = uint64 (2305843009213690000) + uint64 (1:1e6);
octave:2> tic; isprime (n); toc
Elapsed time is 0.213766 seconds.
octave:3> n = uint64 (1084978968791);
octave:4> tic; m = factor (n); toc
Elapsed time is 0.066196 seconds.


Dmitri.
-- 


(file #58731)

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