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Using a better algorithm based on property of primes.

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I recently found out that `p` being prime, while `p > 3`, then
`p = 6*k (+/-) 1`.
This commit is contained in:
Nicolás A. Ortega Froysa
2019-10-08 17:58:08 +02:00
parent 2cfc24afb7
commit 84687f86c1
4 changed files with 84 additions and 22 deletions
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38
src/main.c
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@@ -18,6 +18,7 @@
#include "globals.h"
#include "llist.h"
#include "prime_test.h"
#include <signal.h>
#include <stdio.h>
@@ -35,40 +36,35 @@ int main() {
signal(SIGINT, quit_signal);
mpz_t tnum; // number to be tested for prime-ness
mpz_t tsqrt; // square root of tnum
mpz_t aux; // auxilary number to test against tnum
mpz_t r; // remainder from modulus operation
mpz_t test_base; // number used to get tested numbers
mpz_t p0, p1; // numbers to be tested for prime-ness.
mpz_inits(tnum, tsqrt, aux, r, NULL);
mpz_set_ui(tnum, 3);
mpz_sqrt(tsqrt, tnum);
mpz_inits(test_base, p0, p1, NULL);
mpz_set_ui(test_base, 6);
puts("2");
puts("3");
while(run)
{
mpz_set_ui(aux, 3);
int is_prime = 1;
while(mpz_cmp(aux, tsqrt) <= 0)
{
mpz_mod(r, tnum, aux);
if(mpz_cmp_ui(r, 0) == 0)
is_prime = 0;
mpz_add_ui(aux, aux, 2);
}
mpz_sub_ui(p0, test_base, 1); // p0 = test_base - 1
mpz_add_ui(p1, test_base, 1); // p0 = test_base + 1
if(is_prime)
if(test_prime(p0))
{
mpz_out_str(stdout, 10, tnum);
mpz_out_str(stdout, 10, p0);
printf("\n");
}
if(test_prime(p1))
{
mpz_out_str(stdout, 10, p1);
printf("\n");
}
mpz_add_ui(tnum, tnum, 2);
mpz_sqrt(tsqrt, tnum);
mpz_add_ui(test_base, test_base, 6);
}
mpz_clears(tnum, tsqrt, aux, r, NULL);
mpz_clears(test_base, p0, p1, NULL);
return 0;
}