3 ms·
Show HN: Super fast continuous prime sieve
- eesmith 4y agoIt uses SageMath. Replace ".nbits()" with ".bit_length()" for normal Python (documentation says nbits is an alias: https://doc.sagemath.org/html/en/reference/rings_standard/sage/rings/integer.html#sage.rings.integer.Integer.nbits https://doc.sagemath.org/html/en/reference/rings_standard/sa... ). You'll also need to remove the IPython import if not using a notebook. Curiously, the listed output includes: First 5 primes found and last five primes found [2, 3, 11, 13, 17] ... [4194295, 4194299, 4194301, 4194305, 4194307] 5 and 7 are not on that list. And 4194295 = 5 * 7 * 293 * 409 is not prime, and 4194299 = 29 * 61 * 2371 is also not prime. And 4194305 is clearly not prime either. How is this supposed to be a prime sieve?
- yarg 4y agoIt isn't, at all. https://en.wikipedia.org/wiki/Sieve_of_Eratosthenes https://en.wikipedia.org/wiki/Sieve_of_Eratosthenes There's quite a cool GIF on the wikipedia page that shows the actual (fixed size) algorithm. I was hoping that this would be an expanding generalisation of that, but it really isn't.