void fmpz_primorial(fmpz_t res, long n)
{
mp_size_t len, pi;
ulong bits;
__mpz_struct * mpz_ptr;
if (n <= LARGEST_ULONG_PRIMORIAL)
{
if (n <= 2)
fmpz_set_ui(res, 1 + (n==2));
else
fmpz_set_ui(res, ULONG_PRIMORIALS[(n-1)/2-1]);
return;
}
pi = n_prime_pi(n);
n_compute_primes(pi);
bits = FLINT_BIT_COUNT(flint_primes[pi - 1]);
mpz_ptr = _fmpz_promote(res);
mpz_realloc2(mpz_ptr, pi*bits);
len = mpn_prod_limbs(mpz_ptr->_mp_d, flint_primes, pi, bits);
mpz_ptr->_mp_size = len;
}
void
_qseive(const mp_limb_t n, const mp_limb_t B)
{
nmod_sparse_mat_t M;
mp_limb_t quad, *quads, *xs, x, i = 0, j, piB = n_prime_pi(B);
const mp_limb_t * ps = n_primes_arr_readonly(piB + 2);
const double * pinvs = n_prime_inverses_arr_readonly(piB + 2);
mzd_t *K;
/* init */
quads = (mp_limb_t *)malloc((piB + 1)*sizeof(mp_limb_t *));
xs = (mp_limb_t *)malloc((piB + 1)*sizeof(mp_limb_t *));
K = mzd_init(piB + 1, 1);
nmod_sparse_mat_init(M, piB + 1, piB + 1, 2);
printf("init done\n");
printf("using %ld primes\n", piB);
/* seive */
for (x = n_sqrt(n), i = 0; i <= piB; x++)
{
quad = x*x - n;
if (quad == 0)
continue;
for (j = 0; j < piB; j++)
n_remove2_precomp(&quad, ps[j], pinvs[j]);
if (quad == 1) /* was B-smooth */
{
quads[i] = x*x - n;
quad = x*x - n;
for (j = 0; j < piB; j++)
{
if (n_remove2_precomp(&quad, ps[j], pinvs[j]) % 2)
_nmod_sparse_mat_set_entry(M, j, i, M->row_supports[j], 1);
}
xs[i] = x;
i++;
}
}
printf("data collection done\n");
n_cleanup_primes();
_bw(K, M, 1, 2, 7, 7);
printf("procesing complete\n");
mzd_print(K);
int done = 0;
for (j = 0; !done; j++)
{
fmpz_t a, b, diff, N;
fmpz_init_set_ui(a, 1);
fmpz_init_set_ui(b, 1);
fmpz_init_set_ui(N, n);
fmpz_init(diff);
for (i = 0; i < piB; i++)
{
if (mzd_read_bit(K, i, j))
{
fmpz_mul_ui(a, a, xs[i]);
fmpz_mul_ui(b, b, quads[i]);
}
}
assert(fmpz_is_square(b));
fmpz_sqrt(b, b);
if (fmpz_mod_ui(a, a, n) != fmpz_mod_ui(b, b, n) && fmpz_mod_ui(a, a, n) != n - fmpz_mod_ui(b, b, n))
{
done = 1;
fmpz_print(a);
printf("\n");
fmpz_print(b);
printf("\n");
fmpz_sub(diff, a, b);
fmpz_gcd(a, diff, N);
fmpz_divexact(b, N, a);
fmpz_print(a);
printf("\n");
fmpz_print(b);
}
fmpz_clear(a);
fmpz_clear(b);
fmpz_clear(N);
fmpz_clear(diff);
}
/* cleanup */
free(quads);
free(xs);
mzd_free(K);
nmod_sparse_mat_clear(M);
return;
}