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95.121% accuracy (i.imgur.com)
submitted 1 year ago by [email protected] to c/[email protected]
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[-] [email protected] 17 points 1 year ago

Wait till you include floating numbers. "There are an infinite numbe of numbers between any two natural numbers" So technically you could increase that percentage to 99.9999....%

[-] [email protected] 25 points 1 year ago

You don't even need floats for that. Just increase the amount of tests.

[-] [email protected] 14 points 1 year ago

It would be very easy to increase that to 100%, if you're prepared to ignore enough data...

[-] [email protected] 5 points 1 year ago

Actually it would approach 100% without ignoring data wouldn’t it?

[-] [email protected] 2 points 1 year ago

But the only way it would actually get there depends on you, and your willingness to ignore data. :)

[-] [email protected] 9 points 1 year ago* (last edited 1 year ago)

A few calculations I did last time I saw this meme (over at [email protected]):

  • 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). Solving 99.9995 = 100 - 100 / ln(x) for x gives e^200000 or 7.88 × 10^86858. In other words, the universe will end before any current computer could check that many numbers.

Edit: Fixed community link

[-] [email protected] 3 points 1 year ago

Hi there! Looks like you linked to a Lemmy community using a URL instead of its name, which doesn't work well for people on different instances. Try fixing it like this: [email protected]

[-] [email protected] 2 points 1 year ago

I think a more concise answer to the second one would be; it depends on where you decide to round, but as you run it, it approaches 100%, or 99.99 repeating (which is 100%)

[-] [email protected] 3 points 1 year ago

The screenshot displays 3 decimal places, which is the the precision I used. As it turns out, even just rounding to the nearest integer still requires checking more numbers than we even have the primes enumerated for (e^200 or 7x10^86)

[-] [email protected] 2 points 1 year ago

Ah, ok yeah that makes sense.

[-] [email protected] 5 points 1 year ago

By the prime number theorem, if the tests go from 1 to N, the accuracy will be 1 - 1 / ln(N). They should have kept going for better accuracy.

[-] [email protected] 5 points 1 year ago

The Sieve of Justafewofthese.

[-] [email protected] 2 points 1 year ago

Aw man, my prime number classifier is only 4.879% accurate. :(

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this post was submitted on 08 Jul 2023
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Math Memes

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