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Looking to impress your Ruby friends by calculating the largest known prime, 2**136_279_841-1? On Ruby 3.4.0-preview2 and earlier, 2**136_279_841-1 logs a warning and returns Infinity 😔. Thanks to @mametter.bsky.social, Ruby 3.4 will handle this calculation just fine! github.com/ruby/ruby/pu... 🧵

Knowing this, you excitedly use your ruby manager of choice to pull down ruby master (rvm install ruby-head)! You run `ruby -e "puts 2**136_279_841-1"`, and your excitement is slowly eroded. An hour into calculating, you terminate the command in frustration 😫. Is @mametter.bsky.social a LIAR?! /2

As it turns out, there is critically important library you need for accelerating "Bignum" calculations: GMP, the GNU Multiple Precision Arithmetic Library. It's even specifically mentioned in the CRuby guide to building ruby: docs.ruby-lang.org/en/master/co... /3

Without it, you can kiss your largest prime calculating dreams goodbye 👋 You reinstall ruby head, making sure gmp is available `brew install gmp rvm reinstall ruby-head --with-gmp-dir=$(brew --prefix gmp)` With a bit of hope in your heart, you try again: `ruby -e "puts 2**136_279_841-1"` /4

This was all inspired by @matz.bsky.social's keynote at #RubyConf - where he mentioned that Ruby 3.4 can now calculate the largest known prime. For fun, I tried it on my mac and just let it keep running - 2 hours later, it was still running! I'd never heard of GMP, but now I know! gmplib.org /🧵

I like a lot these explorations! :)

Thanks @lucianghinda.com ! I tend to overthink posting things - that they need to be super in-depth and polished - so i'm aiming to post shorter things more frequently 🙂