From: mame@... Date: 2020-01-05T01:41:09+00:00 Subject: [ruby-core:96668] [Ruby master Feature#16468] Switch to Miller-Rabin for Prime.prime? Issue #16468 has been updated by mame (Yusuke Endoh). It can fall back to APR-CL primality test when Miller-Rabin does not work. In my personal opinion, it would be best to keep prime.rb simple because it is a hobby library. You may be interested in my gem: https://github.com/mame/faster_prime ---------------------------------------- Feature #16468: Switch to Miller-Rabin for Prime.prime? https://bugs.ruby-lang.org/issues/16468#change-83650 * Author: steveb3210 (Stephen Blackstone) * Status: Open * Priority: Normal * Assignee: * Target version: ---------------------------------------- The miller-rabin algorithm is a non-deterministic primality test, however it is known that below 2**64, you can always get a deterministic answer by only checking a=[2,3,5,7,11,13,17,19,23, 29, 31, 37] Given that Prime.prime? would never respond in a reasonable amount of time for larger numbers, we can gain much more utility and performance by switching.. ``` user system total real miller_rabin: random set 0.150000 0.000000 0.150000 ( 0.152212) Prime.prime?: random set 0.270000 0.000000 0.270000 ( 0.281257) user system total real miller_rabin: 16 digits 0.010000 0.000000 0.010000 ( 0.000300) Prime.prime? 16 digits 2.200000 0.020000 2.220000 ( 2.368247) user system total real miller_rabin: 2-10000 0.030000 0.000000 0.030000 ( 0.035752) Prime.prime? 2-10000 0.020000 0.000000 0.020000 ( 0.022948) ---Files-------------------------------- patch.diff (1.75 KB) -- https://bugs.ruby-lang.org/ Unsubscribe: