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Groups > comp.lang.c++ > #91464
| From | Ben Bacarisse <ben.usenet@bsb.me.uk> |
|---|---|
| Newsgroups | comp.lang.c++ |
| Subject | Re: Sieve of Eratosthenes |
| Date | 2023-08-28 23:41 +0100 |
| Organization | A noiseless patient Spider |
| Message-ID | <873502n61v.fsf@bsb.me.uk> (permalink) |
| References | (2 earlier) <ubjrqh$3g7ve$1@redfloyd.dont-email.me> <86msyq5rqu.fsf@linuxsc.com> <56146f63-17d7-40cc-8c42-4f29c922a8c4n@googlegroups.com> <874jkknizq.fsf@bsb.me.uk> <861qfmyft6.fsf@linuxsc.com> |
Tim Rentsch <tr.17687@z991.linuxsc.com> writes:
> Ben Bacarisse <ben.usenet@bsb.me.uk> writes:
>
>> I wanted to try a newer algorithm, so I coded up a rather naive
>> version of Atkin & Bernstein's sieve in C. It needs some tidying
>> and I imagine a bit can be shaved off the time.
>
> Thank you for this. Would you mind posting your code?
Hmm... It's a bit of a mess... but sure.
#include <stdio.h>
#include <stdlib.h>
#include <stdbool.h>
typedef unsigned int nat;
typedef unsigned long long int big_nat;
nat isqrt(nat n)
{
if (n < 2)
return n;
nat s = (isqrt(n >> 2) << 1) + 1;
return s - (s*s > n);
}
static inline void *bitset(nat n)
{
return calloc(1, n/8 + 1);
}
static inline void bitset_clear(void *set, nat n)
{
((unsigned char *)set)[n/8] &= ~(1 << n%8);
}
static inline void bitset_flip(void *set, nat n)
{
((unsigned char *)set)[n/8] ^= 1 << n%8;
}
static inline bool bitset_test(const void *set, nat n)
{
return ((const unsigned char *)set)[n/8] & (1 << n%8);
}
void *primes_up_to(nat n)
{
#define B(n) (1ull << (n))
typedef big_nat small_set;
nat sqrt_n = isqrt(n);
void *pset = bitset(n);
static small_set s1 =
B(1) | B(13) | B(17) | B(29) | B(37) | B(41) | B(49) | B(53);
for (big_nat x = 1; x <= sqrt_n; x++) {
for (nat y = 1; y <= sqrt_n; y += 2) {
big_nat m = 4*x*x + y*y;
if ((B(m % 60) & s1) && m <= n)
bitset_flip(pset, m);
}
}
static small_set s2 = B(7) | B(19) | B(31) | B(43);
for (big_nat x = 1; x <= sqrt_n; x += 2) {
for (nat y = 2; y <= sqrt_n; y += 2) {
big_nat m = 3*x*x + y*y;
if ((B(m % 60) & s2) && m <= n)
bitset_flip(pset, m);
}
}
static small_set s3 = B(11) | B(23) | B(47) | B(59);
for (big_nat x = 2; x <= sqrt_n; x++) {
for (int y = x - 1; y >= 1; y -= 2) {
big_nat m = 3*x*x - y*y;
if ((B(m % 60) & s3) && m <= n)
bitset_flip(pset, m);
}
}
static small_set s =
B(1) | B(7) | B(11) | B(13) | B(17) | B(19) | B(23) | B(29) |
B(31) | B(37) | B(41) | B(43) | B(47) | B(49) | B(53) | B(59);
for (big_nat m = 2; m <= n; m++) {
if (!(B(m % 60) & s))
continue;
big_nat mm = m*m;
if (mm > n)
break;
if (bitset_test(pset, m)) {
for (big_nat m2 = 1; m2 <= n; m2++) {
if (!(B(m2 % 60) & s))
continue;
big_nat c = mm * m2;
if (c > n)
break;
bitset_clear(pset, c);
}
}
}
bitset_flip(pset, 2);
bitset_flip(pset, 3);
bitset_flip(pset, 5);
return pset;
}
int main(int argc, char **argv)
{
int p = argc > 1 ? atoi(argv[1]) : 32;
nat n = (nat)-1 >> 32 - p;
fprintf(stderr, "p=%d, n=%u\n", p, n);
void *pset = primes_up_to(n);
nat count = 0;
while (n > 0)
if (bitset_test(pset, n--))
count += 1;
printf("%u\n", count);
free(pset);
}
I wanted to get rid of the big_nat type. I's sure it can be written
using only 32-bit types.
> Also do
> you have a reference for the Atkin/Bernstein algorithm (or even
> better, code?)?
Well, there's this: https://en.wikipedia.org/wiki/Sieve_of_Atkin
--
Ben.
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Sieve of Eratosthenes Bonita Montero <Bonita.Montero@gmail.com> - 2023-08-16 15:37 +0200
Re: Sieve of Eratosthenes wij <wyniijj5@gmail.com> - 2023-08-16 10:57 -0700
Re: Sieve of Eratosthenes Bonita Montero <Bonita.Montero@gmail.com> - 2023-08-16 20:21 +0200
Re: Sieve of Eratosthenes wij <wyniijj5@gmail.com> - 2023-08-16 12:17 -0700
Re: Sieve of Eratosthenes Paavo Helde <eesnimi@osa.pri.ee> - 2023-08-16 21:44 +0300
Re: Sieve of Eratosthenes wij <wyniijj5@gmail.com> - 2023-08-16 12:09 -0700
Re: Sieve of Eratosthenes "Alf P. Steinbach" <alf.p.steinbach@gmail.com> - 2023-08-16 23:17 +0200
Re: Sieve of Eratosthenes "Alf P. Steinbach" <alf.p.steinbach@gmail.com> - 2023-08-16 23:21 +0200
Re: Sieve of Eratosthenes "Alf P. Steinbach" <alf.p.steinbach@gmail.com> - 2023-08-16 23:39 +0200
Re: Sieve of Eratosthenes "Alf P. Steinbach" <alf.p.steinbach@gmail.com> - 2023-08-16 23:59 +0200
Re: Sieve of Eratosthenes "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2023-08-16 16:27 -0700
Re: Sieve of Eratosthenes red floyd <no.spam.here@its.invalid> - 2023-08-16 18:06 -0700
Re: Sieve of Eratosthenes Tim Rentsch <tr.17687@z991.linuxsc.com> - 2023-08-16 19:26 -0700
Re: Sieve of Eratosthenes Öö Tiib <ootiib@hot.ee> - 2023-08-27 12:26 -0700
Re: Sieve of Eratosthenes Ben Bacarisse <ben.usenet@bsb.me.uk> - 2023-08-28 00:49 +0100
Re: Sieve of Eratosthenes Öö Tiib <ootiib@hot.ee> - 2023-08-27 23:23 -0700
Re: Sieve of Eratosthenes "Alf P. Steinbach" <alf.p.steinbach@gmail.com> - 2023-08-28 15:53 +0200
Re: Sieve of Eratosthenes Öö Tiib <ootiib@hot.ee> - 2023-08-28 09:03 -0700
Re: Sieve of Eratosthenes Bonita Montero <Bonita.Montero@gmail.com> - 2023-08-28 18:47 +0200
Re: Sieve of Eratosthenes Bonita Montero <Bonita.Montero@gmail.com> - 2023-08-30 13:01 +0200
Re: Sieve of Eratosthenes Muttley@dastardlyhq.com - 2023-08-30 15:38 +0000
Re: Sieve of Eratosthenes Bonita Montero <Bonita.Montero@gmail.com> - 2023-08-30 18:31 +0200
Re: Sieve of Eratosthenes Muttley@dastardlyhq.com - 2023-08-31 08:22 +0000
Re: Sieve of Eratosthenes Bonita Montero <Bonita.Montero@gmail.com> - 2023-08-31 11:00 +0200
Re: Sieve of Eratosthenes Muttley@dastardlyhq.com - 2023-08-31 15:23 +0000
Re: Sieve of Eratosthenes Bonita Montero <Bonita.Montero@gmail.com> - 2023-08-31 17:28 +0200
Re: Sieve of Eratosthenes Bonita Montero <Bonita.Montero@gmail.com> - 2023-08-31 11:52 +0200
Re: Sieve of Eratosthenes Muttley@dastardlyhq.com - 2023-08-31 15:22 +0000
Re: Sieve of Eratosthenes Bonita Montero <Bonita.Montero@gmail.com> - 2023-08-31 17:32 +0200
Re: Sieve of Eratosthenes Muttley@dastardlyhq.com - 2023-08-31 15:44 +0000
Re: Sieve of Eratosthenes Bonita Montero <Bonita.Montero@gmail.com> - 2023-08-31 17:50 +0200
Re: Sieve of Eratosthenes Muttley@dastardlyhq.com - 2023-09-01 10:26 +0000
Re: Sieve of Eratosthenes Bonita Montero <Bonita.Montero@gmail.com> - 2023-09-01 12:59 +0200
Re: Sieve of Eratosthenes Muttley@dastardlyhq.com - 2023-09-01 12:30 +0000
Re: Sieve of Eratosthenes Bonita Montero <Bonita.Montero@gmail.com> - 2023-09-01 15:33 +0200
Re: Sieve of Eratosthenes Muttley@dastardlyhq.com - 2023-09-01 13:49 +0000
Re: Sieve of Eratosthenes Bonita Montero <Bonita.Montero@gmail.com> - 2023-09-01 15:59 +0200
Re: Sieve of Eratosthenes Muttley@dastardlyhq.com - 2023-09-01 14:03 +0000
Re: Sieve of Eratosthenes Bonita Montero <Bonita.Montero@gmail.com> - 2023-09-01 16:15 +0200
Re: Sieve of Eratosthenes Muttley@dastardlyhq.com - 2023-09-01 14:39 +0000
Re: Sieve of Eratosthenes Bonita Montero <Bonita.Montero@gmail.com> - 2023-09-01 16:59 +0200
Re: Sieve of Eratosthenes Muttley@dastardlyhq.com - 2023-09-01 15:01 +0000
Re: Sieve of Eratosthenes Bonita Montero <Bonita.Montero@gmail.com> - 2023-09-01 17:05 +0200
Re: Sieve of Eratosthenes Muttley@dastardlyhq.com - 2023-09-01 15:08 +0000
Re: Sieve of Eratosthenes Bonita Montero <Bonita.Montero@gmail.com> - 2023-09-01 17:15 +0200
Re: Sieve of Eratosthenes Ben Bacarisse <ben.usenet@bsb.me.uk> - 2023-08-31 21:33 +0100
Re: Sieve of Eratosthenes Bonita Montero <Bonita.Montero@gmail.com> - 2023-09-01 05:35 +0200
Re: Sieve of Eratosthenes scott@slp53.sl.home (Scott Lurndal) - 2023-08-31 14:43 +0000
Re: Sieve of Eratosthenes Bonita Montero <Bonita.Montero@gmail.com> - 2023-08-31 16:57 +0200
Re: Sieve of Eratosthenes scott@slp53.sl.home (Scott Lurndal) - 2023-08-31 16:10 +0000
Re: Sieve of Eratosthenes Muttley@dastardlyhq.com - 2023-08-31 15:25 +0000
Re: Sieve of Eratosthenes Bonita Montero <Bonita.Montero@gmail.com> - 2023-08-31 17:33 +0200
Re: Sieve of Eratosthenes scott@slp53.sl.home (Scott Lurndal) - 2023-08-31 16:12 +0000
Re: Sieve of Eratosthenes Ben Bacarisse <ben.usenet@bsb.me.uk> - 2023-08-28 23:08 +0100
Re: Sieve of Eratosthenes Tim Rentsch <tr.17687@z991.linuxsc.com> - 2023-08-28 15:15 -0700
Re: Sieve of Eratosthenes Ben Bacarisse <ben.usenet@bsb.me.uk> - 2023-08-28 23:41 +0100
Re: Sieve of Eratosthenes Tim Rentsch <tr.17687@z991.linuxsc.com> - 2023-08-30 17:45 -0700
Re: Sieve of Eratosthenes Ben Bacarisse <ben.usenet@bsb.me.uk> - 2023-08-31 03:18 +0100
Re: Sieve of Eratosthenes Tim Rentsch <tr.17687@z991.linuxsc.com> - 2023-08-28 15:08 -0700
Re: Sieve of Eratosthenes Bonita Montero <Bonita.Montero@gmail.com> - 2023-08-17 08:42 +0200
Re: Sieve of Eratosthenes Bonita Montero <Bonita.Montero@gmail.com> - 2023-08-17 11:38 +0200
Re: Sieve of Eratosthenes "Alf P. Steinbach" <alf.p.steinbach@gmail.com> - 2023-08-17 12:50 +0200
Re: Sieve of Eratosthenes Bonita Montero <Bonita.Montero@gmail.com> - 2023-08-17 13:10 +0200
Re: Sieve of Eratosthenes Bonita Montero <Bonita.Montero@gmail.com> - 2023-08-17 17:47 +0200
Re: Sieve of Eratosthenes Bonita Montero <Bonita.Montero@gmail.com> - 2023-08-21 11:00 +0200
Re: Sieve of Eratosthenes Muttley@dastardlyhq.com - 2023-08-21 17:19 +0000
Re: Sieve of Eratosthenes Bonita Montero <Bonita.Montero@gmail.com> - 2023-08-21 19:50 +0200
Re: Sieve of Eratosthenes Muttley@dastardlyhq.com - 2023-08-21 18:12 +0000
Re: Sieve of Eratosthenes Bonita Montero <Bonita.Montero@gmail.com> - 2023-08-21 20:22 +0200
Re: Sieve of Eratosthenes Muttley@dastardlyhq.com - 2023-08-21 19:01 +0000
Re: Sieve of Eratosthenes Bonita Montero <Bonita.Montero@gmail.com> - 2023-08-22 05:27 +0200
Re: Sieve of Eratosthenes Öö Tiib <ootiib@hot.ee> - 2023-08-21 23:25 -0700
Re: Sieve of Eratosthenes Bonita Montero <Bonita.Montero@gmail.com> - 2023-08-22 11:23 +0200
Re: Sieve of Eratosthenes Bonita Montero <Bonita.Montero@gmail.com> - 2023-08-22 11:59 +0200
Re: Sieve of Eratosthenes Öö Tiib <ootiib@hot.ee> - 2023-08-22 05:15 -0700
Re: Sieve of Eratosthenes Bonita Montero <Bonita.Montero@gmail.com> - 2023-08-22 14:23 +0200
Re: Sieve of Eratosthenes Muttley@dastardlyhq.com - 2023-08-22 06:56 +0000
Re: Sieve of Eratosthenes Bonita Montero <Bonita.Montero@gmail.com> - 2023-08-22 11:27 +0200
Re: Sieve of Eratosthenes Bonita Montero <Bonita.Montero@gmail.com> - 2023-08-22 11:34 +0200
Re: Sieve of Eratosthenes Muttley@dastardlyhq.com - 2023-08-22 14:13 +0000
Re: Sieve of Eratosthenes Bonita Montero <Bonita.Montero@gmail.com> - 2023-08-22 16:17 +0200
Re: Sieve of Eratosthenes Muttley@dastardlyhq.com - 2023-08-22 14:27 +0000
Re: Sieve of Eratosthenes Bonita Montero <Bonita.Montero@gmail.com> - 2023-08-22 16:48 +0200
Re: Sieve of Eratosthenes Muttley@dastardlyhq.com - 2023-08-22 14:57 +0000
Re: Sieve of Eratosthenes Bonita Montero <Bonita.Montero@gmail.com> - 2023-08-22 17:00 +0200
Re: Sieve of Eratosthenes Muttley@dastardlyhq.com - 2023-08-22 17:56 +0000
Re: Sieve of Eratosthenes Bonita Montero <Bonita.Montero@gmail.com> - 2023-08-22 20:13 +0200
Re: Sieve of Eratosthenes Muttley@dastardlyhq.com - 2023-08-22 18:18 +0000
Re: Sieve of Eratosthenes Bonita Montero <Bonita.Montero@gmail.com> - 2023-08-22 20:50 +0200
Re: Sieve of Eratosthenes Muttley@dastardlyhq.com - 2023-08-23 06:51 +0000
Re: Sieve of Eratosthenes Bonita Montero <Bonita.Montero@gmail.com> - 2023-08-23 09:59 +0200
Re: Sieve of Eratosthenes Richard Damon <Richard@Damon-Family.org> - 2023-08-23 07:52 -0400
Re: Sieve of Eratosthenes Bonita Montero <Bonita.Montero@gmail.com> - 2023-08-23 14:40 +0200
Re: Sieve of Eratosthenes Muttley@dastardlyhq.com - 2023-08-23 14:24 +0000
Re: Sieve of Eratosthenes Bonita Montero <Bonita.Montero@gmail.com> - 2023-08-23 16:30 +0200
Re: Sieve of Eratosthenes Muttley@dastardlyhq.com - 2023-08-23 14:36 +0000
Re: Sieve of Eratosthenes Bonita Montero <Bonita.Montero@gmail.com> - 2023-08-23 16:38 +0200
Re: Sieve of Eratosthenes Muttley@dastardlyhq.com - 2023-08-23 14:43 +0000
Re: Sieve of Eratosthenes Bonita Montero <Bonita.Montero@gmail.com> - 2023-08-23 16:45 +0200
Re: Sieve of Eratosthenes Muttley@dastardlyhq.com - 2023-08-23 17:49 +0000
Re: Sieve of Eratosthenes Bonita Montero <Bonita.Montero@gmail.com> - 2023-08-23 20:05 +0200
Re: Sieve of Eratosthenes Muttley@dastardlyhq.com - 2023-08-24 17:18 +0000
Re: Sieve of Eratosthenes Bonita Montero <Bonita.Montero@gmail.com> - 2023-08-24 19:20 +0200
Re: Sieve of Eratosthenes Daniel <danielaparker@gmail.com> - 2023-08-23 11:13 -0700
Re: Sieve of Eratosthenes Bonita Montero <Bonita.Montero@gmail.com> - 2023-08-23 20:17 +0200
Re: Sieve of Eratosthenes "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2023-08-23 11:20 -0700
Re: Sieve of Eratosthenes Bonita Montero <Bonita.Montero@gmail.com> - 2023-08-23 20:24 +0200
Re: Sieve of Eratosthenes Muttley@dastardlyhq.com - 2023-08-24 17:25 +0000
Re: Sieve of Eratosthenes Bonita Montero <Bonita.Montero@gmail.com> - 2023-08-24 19:29 +0200
Re: Sieve of Eratosthenes Muttley@dastardlyhq.com - 2023-08-24 17:40 +0000
Re: Sieve of Eratosthenes Bonita Montero <Bonita.Montero@gmail.com> - 2023-08-24 19:49 +0200
Re: Sieve of Eratosthenes Muttley@dastardlyhq.com - 2023-08-25 16:07 +0000
Re: Sieve of Eratosthenes Bonita Montero <Bonita.Montero@gmail.com> - 2023-08-25 18:10 +0200
Re: Sieve of Eratosthenes Muttley@dastardlyhq.com - 2023-08-25 16:15 +0000
Re: Sieve of Eratosthenes Bonita Montero <Bonita.Montero@gmail.com> - 2023-08-25 18:18 +0200
Re: Sieve of Eratosthenes Muttley@dastardlyhq.com - 2023-08-26 08:03 +0000
Re: Sieve of Eratosthenes Bonita Montero <Bonita.Montero@gmail.com> - 2023-08-26 10:16 +0200
Re: Sieve of Eratosthenes Muttley@dastardlyhq.com - 2023-08-26 08:27 +0000
Re: Sieve of Eratosthenes Daniel <danielaparker@gmail.com> - 2023-08-23 11:37 -0700
Re: Sieve of Eratosthenes "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2023-08-26 15:33 -0700
Re: Sieve of Eratosthenes Muttley@dastardlyhq.com - 2023-08-23 14:20 +0000
Re: Sieve of Eratosthenes Bonita Montero <Bonita.Montero@gmail.com> - 2023-08-23 16:32 +0200
Re: Sieve of Eratosthenes Muttley@dastardlyhq.com - 2023-08-23 14:41 +0000
Re: Sieve of Eratosthenes Bonita Montero <Bonita.Montero@gmail.com> - 2023-08-23 16:47 +0200
Re: Sieve of Eratosthenes Muttley@dastardlyhq.com - 2023-08-23 17:51 +0000
Re: Sieve of Eratosthenes Bonita Montero <Bonita.Montero@gmail.com> - 2023-08-23 20:09 +0200
Re: Sieve of Eratosthenes scott@slp53.sl.home (Scott Lurndal) - 2023-08-23 18:51 +0000
Re: Sieve of Eratosthenes "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2023-08-24 11:25 -0700
Re: Sieve of Eratosthenes Muttley@dastardlyhq.com - 2023-08-24 17:22 +0000
Re: Sieve of Eratosthenes Bonita Montero <Bonita.Montero@gmail.com> - 2023-08-24 19:27 +0200
Re: Sieve of Eratosthenes Muttley@dastardlyhq.com - 2023-08-24 17:37 +0000
Re: Sieve of Eratosthenes Bonita Montero <Bonita.Montero@gmail.com> - 2023-08-24 19:52 +0200
Re: Sieve of Eratosthenes Muttley@dastardlyhq.com - 2023-08-25 16:07 +0000
Re: Sieve of Eratosthenes Daniel <danielaparker@gmail.com> - 2023-08-23 08:00 -0700
Re: Sieve of Eratosthenes scott@slp53.sl.home (Scott Lurndal) - 2023-08-22 15:49 +0000
Re: Sieve of Eratosthenes Muttley@dastardlyhq.com - 2023-08-22 17:58 +0000
Re: Sieve of Eratosthenes scott@slp53.sl.home (Scott Lurndal) - 2023-08-22 18:24 +0000
Re: Sieve of Eratosthenes Muttley@dastardlyhq.com - 2023-08-23 06:50 +0000
Re: Sieve of Eratosthenes wij <wyniijj5@gmail.com> - 2023-08-17 13:43 -0700
Re: Sieve of Eratosthenes "Alf P. Steinbach" <alf.p.steinbach@gmail.com> - 2023-08-18 02:00 +0200
Re: Sieve of Eratosthenes wij <wyniijj5@gmail.com> - 2023-08-18 05:01 -0700
Re: Sieve of Eratosthenes wij <wyniijj5@gmail.com> - 2023-08-18 17:02 -0700
Re: Sieve of Eratosthenes Bonita Montero <Bonita.Montero@gmail.com> - 2023-08-28 06:15 +0200
Re: Sieve of Eratosthenes Bonita Montero <Bonita.Montero@gmail.com> - 2023-08-28 09:43 +0200
Re: Sieve of Eratosthenes Bonita Montero <Bonita.Montero@gmail.com> - 2023-08-29 20:34 +0200
Re: Sieve of Eratosthenes Bonita Montero <Bonita.Montero@gmail.com> - 2023-08-30 19:02 +0200
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