Re: OT: Re: Sieve of Erastosthenes optimized to the max

Am 19.08.2024 um 22:23 schrieb Vir Campestris:

On 16/08/2024 18:35, Bonita Montero wrote:
<snip>

But basically I don't think it is a good idea to skip numbers exept
multiples of two. With the three you save a sixth of memory, with
the five you save a 15-th and at the end you get about 20% less
storage (1 / (2 * 3) + 1 / (2 * 3 * 5) + 1 / (2 * 3 * 5 * 7) ...)
for a lot of computation. That's the point where I dropped this
idea and I think this extra computation is higher than the time
for the saved memory loads.
>

It's not just storage you save, it's also computation.
 That program I published up-thread is almost as fast as yours - within 10% of the elapsed time - while only using a single core. The amount of CPU used is much lower.
 Andy

On my AMD 7990X all primes up to 2 ^ 32 are calculated with my code
with a 65W-setting of the CPU in 0.168s. The total CPU-time is 3.688s.
With your code all primes up to 2 ^ 32 take nearly exactly four seconds
with a single thread. So the overall computation time with my algorithm
is about seconds less.