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

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Sujet : Re: OT: Re: Sieve of Erastosthenes optimized to the max
De : Bonita.Montero (at) *nospam* gmail.com (Bonita Montero)
Groupes : comp.lang.c++
Date : 16. Aug 2024, 18:55:13
Autres entêtes
Organisation : A noiseless patient Spider
Message-ID : <v9o3q1$1h24f$1@raubtier-asyl.eternal-september.org>
References : 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23
User-Agent : Mozilla Thunderbird
Am 16.08.2024 um 19:35 schrieb Bonita Montero:

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.
 
This calculates the percentage of the memory-access-savings:
#include <iostream>
#include <span>
#include <algorithm>
using namespace std;
int main()
{
static unsigned const rawPrimes[] =
{
2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61, 67, 71,
73, 79, 83, 89, 97, 101, 103, 107, 109, 113, 127, 131, 137, 139, 149, 151,
157, 163, 167, 173, 179, 181, 191, 193, 197, 199, 211, 223, 227, 229, 233,
239, 241, 251, 257, 263, 269, 271, 277, 281, 283, 293, 307, 311, 313, 317,
331, 337, 347, 349, 353, 359, 367, 373, 379, 383, 389, 397, 401, 409, 419,
421, 431, 433, 439, 443, 449, 457, 461, 463, 467, 479, 487, 491, 499, 503,
509, 521, 523, 541
};
span primes( rawPrimes );
double sum = 0.0;
auto
rEnd = primes.rend(),
cur = rEnd - 2;
do
{
double add = 1.0;
for_each( cur, rEnd, [&]( int p )
{ add /= p; } );
sum += add;
} while( --cur != primes.rbegin() );
cout << 100 * sum << "%" << endl;
}

Date Sujet#  Auteur
30 Jun 24 * Re: Sieve of Erastosthenes optimized to the max54Vir Campestris
2 Jul 24 `* Re: Sieve of Erastosthenes optimized to the max53Tim Rentsch
2 Jul 24  +- Re: Sieve of Erastosthenes optimized to the max1Vir Campestris
3 Jul 24  `* Re: Sieve of Erastosthenes optimized to the max51Vir Campestris
15 Jul 24   +- Re: Sieve of Erastosthenes optimized to the max1Tim Rentsch
20 Jul 24   +* Re: Sieve of Erastosthenes optimized to the max48Tim Rentsch
25 Jul 24   i`* OT: Re: Sieve of Erastosthenes optimized to the max47Vir Campestris
10 Aug 24   i +* Re: OT: Re: Sieve of Erastosthenes optimized to the max44Tim Rentsch
12 Aug 24   i i+* Re: OT: Re: Sieve of Erastosthenes optimized to the max2Vir Campestris
16 Aug 24   i ii`- Re: OT: Re: Sieve of Erastosthenes optimized to the max1Tim Rentsch
15 Aug 24   i i`* Re: OT: Re: Sieve of Erastosthenes optimized to the max41Vir Campestris
16 Aug 24   i i `* Re: OT: Re: Sieve of Erastosthenes optimized to the max40Tim Rentsch
16 Aug 24   i i  +* Re: OT: Re: Sieve of Erastosthenes optimized to the max38Bonita Montero
16 Aug 24   i i  i+- Re: OT: Re: Sieve of Erastosthenes optimized to the max1Bonita Montero
19 Aug 24   i i  i+* Re: OT: Re: Sieve of Erastosthenes optimized to the max19Vir Campestris
20 Aug 24   i i  ii`* Re: OT: Re: Sieve of Erastosthenes optimized to the max18Bonita Montero
20 Aug 24   i i  ii `* Re: OT: Re: Sieve of Erastosthenes optimized to the max17Bonita Montero
20 Aug 24   i i  ii  +- Re: OT: Re: Sieve of Erastosthenes optimized to the max1Bonita Montero
20 Aug 24   i i  ii  `* Re: OT: Re: Sieve of Erastosthenes optimized to the max15Vir Campestris
20 Aug 24   i i  ii   +- Re: OT: Re: Sieve of Erastosthenes optimized to the max1Bonita Montero
26 Aug 24   i i  ii   `* Re: OT: Re: Sieve of Erastosthenes optimized to the max13Tim Rentsch
27 Aug 24   i i  ii    `* Re: OT: Re: Sieve of Erastosthenes optimized to the max12Bonita Montero
1 Sep 24   i i  ii     `* Re: OT: Re: Sieve of Erastosthenes optimized to the max11Vir Campestris
2 Sep 24   i i  ii      `* Re: OT: Re: Sieve of Erastosthenes optimized to the max10Tim Rentsch
2 Sep 24   i i  ii       +- Re: OT: Re: Sieve of Erastosthenes optimized to the max1Bonita Montero
3 Sep 24   i i  ii       `* Re: OT: Re: Sieve of Erastosthenes optimized to the max8Vir Campestris
28 Sep 24   i i  ii        `* Re: OT: Re: Sieve of Erastosthenes optimized to the max7Tim Rentsch
28 Sep 24   i i  ii         `* Re: OT: Re: Sieve of Erastosthenes optimized to the max6Keith Thompson
2 Oct 24   i i  ii          `* Re: OT: Re: Sieve of Erastosthenes optimized to the max5Vir Campestris
2 Oct 24   i i  ii           +- Re: OT: Re: Sieve of Erastosthenes optimized to the max1Bonita Montero
7 Oct 24   i i  ii           `* Re: OT: Re: Sieve of Erastosthenes optimized to the max3Tim Rentsch
20 Oct 24   i i  ii            `* Re: OT: Re: Sieve of Erastosthenes optimized to the max2Vir Campestris
4 Nov 24   i i  ii             `- Re: OT: Re: Sieve of Erastosthenes optimized to the max1Tim Rentsch
19 Aug 24   i i  i+* Re: OT: Re: Sieve of Erastosthenes optimized to the max12Vir Campestris
20 Aug 24   i i  ii+* Re: OT: Re: Sieve of Erastosthenes optimized to the max4red floyd
20 Aug 24   i i  iii+* Re: OT: Re: Sieve of Erastosthenes optimized to the max2Vir Campestris
26 Aug 24   i i  iiii`- Re: OT: Re: Sieve of Erastosthenes optimized to the max1Tim Rentsch
26 Aug 24   i i  iii`- Re: OT: Re: Sieve of Erastosthenes optimized to the max1Tim Rentsch
20 Aug 24   i i  ii+* Re: OT: Re: Sieve of Erastosthenes optimized to the max3Bonita Montero
20 Aug 24   i i  iii+- Re: OT: Re: Sieve of Erastosthenes optimized to the max1Bonita Montero
20 Aug 24   i i  iii`- Re: OT: Re: Sieve of Erastosthenes optimized to the max1Bonita Montero
20 Aug 24   i i  ii`* Re: OT: Re: Sieve of Erastosthenes optimized to the max4Bonita Montero
22 Aug 24   i i  ii `* Re: OT: Re: Sieve of Erastosthenes optimized to the max3Vir Campestris
22 Aug 24   i i  ii  `* Re: OT: Re: Sieve of Erastosthenes optimized to the max2Bonita Montero
22 Aug 24   i i  ii   `- Re: OT: Re: Sieve of Erastosthenes optimized to the max1Vir Campestris
22 Aug 24   i i  i`* Re: OT: Re: Sieve of Erastosthenes optimized to the max5Vir Campestris
23 Aug 24   i i  i +* Re: OT: Re: Sieve of Erastosthenes optimized to the max3red floyd
26 Aug 24   i i  i i+- Re: OT: Re: Sieve of Erastosthenes optimized to the max1Tim Rentsch
28 Sep 24   i i  i i`- Re: OT: Re: Sieve of Erastosthenes optimized to the max1Andrey Tarasevich
26 Aug 24   i i  i `- Re: OT: Re: Sieve of Erastosthenes optimized to the max1Tim Rentsch
19 Aug 24   i i  `- Re: OT: Re: Sieve of Erastosthenes optimized to the max1Tim Rentsch
11 Aug 24   i +- Re: OT: Re: Sieve of Erastosthenes optimized to the max1Tim Rentsch
11 Aug 24   i `- Re: OT: Re: Sieve of Erastosthenes optimized to the max1Tim Rentsch
23 Jul 24   `- Re: Sieve of Erastosthenes optimized to the max1Tim Rentsch

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