- cross-posted to:
- mathmemes@lemmy.blahaj.zone
- cross-posted to:
- mathmemes@lemmy.blahaj.zone
You must log in or register to comment.
And if you want to increase accuracy you just add more tests
The failures are probably just flake then
“prime on my machine”
I wrote an ai that classifies spam emails with 99.9% accuracy.
Our test set contained 1000 emails, 999 aren’t spam.
The algorithm:
Honestly I’d rather have that, than randomly have to miss some important E-mail because the system put it in the junk folder.
All odd numbers are prime: 1 is prime, 3 is prime, 5 is prime, 7 is prime, 9 is experimental error, 11 is prime, and so on, I don’t have funding to check all of them, but it suggests an avenue of productive further work.
1 is prime
Look, just because it breaks everything, that’s no reason not to include it in a joke. We’ll just have to rebuild the entire edifice of mathematics.
Seriously, thanks for the link, I hadn’t considered the implications of including 1 in the set of primes, and it really does seem to break a lot of ideas.
It’s been a fat minute since I last did any programming outside of batch scripts and AHK… I’m struggling to understand how it’s not returning false for 100% of the tests
It is always returning false, but the screen shows a test, where a non-prime evaluating as false is a pass and a prime evaluating as false is a fail :))
The output shown is the result of a test for the function, not the result of the function itself.
Ooooh I see lol. Thank you!
It’s returning false for all the tests, but it only should be returning false for 95% of them, as 5% are prime.
It even passes over 100% of tests!
Edit: I can’t read floats.
have y’all never seen a float before
The last line reads 95.121 %. I was confused too that it is 121%, but, sadly, no.
How many primes are there before 1 and 2^31. IIRC prime numbers get more and more rare as the number increases. I wouldn’t be surprised if this would pass 99% of tests if tested with all positive 32 bit integers.
Per the prime number theorem, for large enough N the proportion of primes less than or equal to N is approximately 1/log(N). For N = 2^(31) that’s ~0.0465. To get under 1% you’d need N ~ 2^(145).
So you better use 128-bit unsigned integers 😅
Wolfram alpha says it’s about 4.9%. So 4.9% of numbers in the range 1 to 2^31 are prime. It’s more than I expected.
Ah yes, my favorite recurring lemmy post! It even has the same incorrect test output.
Last time I saw this I did a few calculations based on comments people made:
https://l.sw0.com/comment/32691 (when are we going to be able to link to comments across instances?)- There are 9592 prime numbers less than 100,000. Assuming the test suite only tests numbers 1-99999, the accuracy should actually be only 90.408%, not 95.121%
- The 1 trillionth prime number is 29,996,224,275,833. This would mean even the first 29 trillion primes would only get you to 96.667% accuracy.
In response to the question of how long it would take to round up to 100%:
- The density of primes can be approximated using the Prime Number Theorem:
1/ln(x). Solving99.9995 = 100 - 100 / ln(x)for x givese^200000or7.88 × 10^86858. In other words, the universe will end before any current computer could check that many numbers.
But you can use randomised test-cases. Better yet, you can randomise values in test-cases once
and throw away the ones you don’t likeand get arbitrarily close to 100% with a reasonable amount of tests
why would you store comments in git?
Oh. Oh ha ha ha ha you just don’t know ‘checkout’ from ‘check out’. Clean out your desk.
