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o(1) statistical prime approximation
(lemmy.blahaj.zone)
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this post was submitted on 22 Feb 2026
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My favorite part of this is that they test it up to 99999 and we see that it fails for 99991, so that means somewhere in the test they actually implemented a properly working function.
That's a legitimate thing to do if you have a slow implementation that's easy to verify and a fast implementation that isn't.
No, it's always guessing false and 99991 is prime so it isn't right. This isn't the output of the program but the output of the program compared with a better (but probably not faster) isprime program
Yes, that's what I said. They wrote another test program, with a correct implementation of IsPrime in order to test to make sure the pictured one produced the expected output.
Plot twist: the test just checks to see if the input exists in a hardcoded list of all prime numbers under 100000.
https://oeis.org/A000040
I mean people underestimate how usefull lookup tables are. A lookup table of primes for example is basically always just better except the one case where you are searching for primes which is more maths than computer programming anyways. The modern way is to abstract and reimplement everything when there are much cheaper and easier ways of doing it.
Computer programming is a subset of maths and was invented by a mathematition, originally to solve a maths problem...
Yeah but they slowly develop to be their own fields. You wouldnt argue that physics is math either. Or that chemistry could technically be called a very far branch of philosophy. Computer programing, physics, etc are the applied versions of math. You are no longer studying math, you are studying something else with the help of math. Not that it matters much, just makes distinguising between them easier. You can draw the line anywhere but people do generally have a somewhat shared idea of where that lies.
Chemistry is a branch of alchemy
I suppose, but only about insofar as the U.S. is a branch of the British Empire.
Ah gotcha. Or a known list yeah
For prime numbers, since they're quite difficult to calculate and there's not that many of them, that's what's most common.