void
nmod_poly_xgcd_hgcd(nmod_poly_t G, nmod_poly_t S, nmod_poly_t T,
const nmod_poly_t A, const nmod_poly_t B)
{
if (A->length < B->length)
{
nmod_poly_xgcd_hgcd(G, T, S, B, A);
}
else /* lenA >= lenB >= 0 */
{
const slong lenA = A->length, lenB = B->length;
mp_limb_t inv;
if (lenA == 0) /* lenA = lenB = 0 */
{
nmod_poly_zero(G);
nmod_poly_zero(S);
nmod_poly_zero(T);
}
else if (lenB == 0) /* lenA > lenB = 0 */
{
inv = n_invmod(A->coeffs[lenA - 1], A->mod.n);
nmod_poly_scalar_mul_nmod(G, A, inv);
nmod_poly_zero(T);
nmod_poly_set_coeff_ui(S, 0, inv);
S->length = 1;
}
else if (lenB == 1) /* lenA >= lenB = 1 */
{
nmod_poly_fit_length(T, 1);
T->length = 1;
T->coeffs[0] = n_invmod(B->coeffs[0], A->mod.n);
nmod_poly_one(G);
nmod_poly_zero(S);
}
else /* lenA >= lenB >= 2 */
{
mp_ptr g, s, t;
slong lenG;
if (G == A || G == B)
{
g = _nmod_vec_init(FLINT_MIN(lenA, lenB));
}
else
{
nmod_poly_fit_length(G, FLINT_MIN(lenA, lenB));
g = G->coeffs;
}
if (S == A || S == B)
{
s = _nmod_vec_init(FLINT_MAX(lenB - 1, 2));
}
else
{
nmod_poly_fit_length(S, FLINT_MAX(lenB - 1, 2));
s = S->coeffs;
}
if (T == A || T == B)
{
t = _nmod_vec_init(FLINT_MAX(lenA - 1, 2));
}
else
{
nmod_poly_fit_length(T, FLINT_MAX(lenA - 1, 2));
t = T->coeffs;
}
if (lenA >= lenB)
lenG = _nmod_poly_xgcd_hgcd(g, s, t, A->coeffs, lenA,
B->coeffs, lenB, A->mod);
else
lenG = _nmod_poly_xgcd_hgcd(g, t, s, B->coeffs, lenB,
A->coeffs, lenA, A->mod);
if (G == A || G == B)
{
flint_free(G->coeffs);
G->coeffs = g;
G->alloc = FLINT_MIN(lenA, lenB);
}
if (S == A || S == B)
{
flint_free(S->coeffs);
S->coeffs = s;
S->alloc = FLINT_MAX(lenB - 1, 2);
}
if (T == A || T == B)
{
flint_free(T->coeffs);
T->coeffs = t;
T->alloc = FLINT_MAX(lenA - 1, 2);
}
G->length = lenG;
S->length = FLINT_MAX(lenB - lenG, 1);
T->length = FLINT_MAX(lenA - lenG, 1);
MPN_NORM(S->coeffs, S->length);
MPN_NORM(T->coeffs, T->length);
if (G->coeffs[lenG - 1] != 1)
{
inv = n_invmod(G->coeffs[lenG - 1], A->mod.n);
nmod_poly_scalar_mul_nmod(G, G, inv);
nmod_poly_scalar_mul_nmod(S, S, inv);
nmod_poly_scalar_mul_nmod(T, T, inv);
}
}
}
}
void
nmod_poly_xgcd(nmod_poly_t G, nmod_poly_t S, nmod_poly_t T,
const nmod_poly_t A, const nmod_poly_t B)
{
const long lenA = A->length, lenB = B->length;
mp_limb_t inv;
if (lenA == 0)
{
if (lenB == 0)
{
nmod_poly_zero(G);
nmod_poly_zero(S);
nmod_poly_zero(T);
}
else
{
inv = n_invmod(B->coeffs[lenB - 1], B->mod.n);
nmod_poly_scalar_mul_nmod(G, B, inv);
nmod_poly_zero(S);
nmod_poly_set_coeff_ui(T, 0, inv);
T->length = 1;
}
}
else if (lenB == 0)
{
inv = n_invmod(A->coeffs[lenA - 1], A->mod.n);
nmod_poly_scalar_mul_nmod(G, A, inv);
nmod_poly_zero(T);
nmod_poly_set_coeff_ui(S, 0, inv);
S->length = 1;
}
else
{
nmod_poly_t tG, tS, tT;
mp_ptr g, s, t;
long lenG;
if (G == A || G == B)
{
nmod_poly_init2(tG, A->mod.n, FLINT_MIN(lenA, lenB));
g = tG->coeffs;
}
else
{
nmod_poly_fit_length(G, FLINT_MIN(lenA, lenB));
g = G->coeffs;
}
if (S == A || S == B)
{
nmod_poly_init2(tS, A->mod.n, lenB - 1);
s = tS->coeffs;
}
else
{
nmod_poly_fit_length(S, lenB - 1);
s = S->coeffs;
}
if (T == A || T == B)
{
nmod_poly_init2(tT, A->mod.n, lenA - 1);
t = tT->coeffs;
}
else
{
nmod_poly_fit_length(T, lenA - 1);
t = T->coeffs;
}
if (lenA >= lenB)
lenG = _nmod_poly_xgcd(g, s, t, A->coeffs, lenA,
B->coeffs, lenB, A->mod);
else
lenG = _nmod_poly_xgcd(g, t, s, B->coeffs, lenB,
A->coeffs, lenA, A->mod);
if (G == A || G == B)
{
nmod_poly_swap(tG, G);
nmod_poly_clear(tG);
}
if (S == A || S == B)
{
nmod_poly_swap(tS, S);
nmod_poly_clear(tS);
}
if (T == A || T == B)
{
nmod_poly_swap(tT, T);
nmod_poly_clear(tT);
}
G->length = lenG;
S->length = lenB - lenG;
T->length = lenA - lenG;
MPN_NORM(S->coeffs, S->length);
MPN_NORM(T->coeffs, T->length);
if (G->coeffs[lenG - 1] != 1)
{
inv = n_invmod(G->coeffs[lenG - 1], A->mod.n);
nmod_poly_scalar_mul_nmod(G, G, inv);
nmod_poly_scalar_mul_nmod(S, S, inv);
nmod_poly_scalar_mul_nmod(T, T, inv);
}
}
}
int
main(void)
{
int iter;
flint_rand_t state;
flint_randinit(state);
printf("factor....");
fflush(stdout);
/* Default algorithm */
for (iter = 0; iter < 100; iter++)
{
int result = 1;
nmod_poly_t pol1, poly, quot, rem, product;
nmod_poly_factor_t res;
mp_limb_t modulus, lead = 1;
long length, num, i, j;
ulong exp[5], prod1;
modulus = n_randtest_prime(state, 0);
nmod_poly_init(pol1, modulus);
nmod_poly_init(poly, modulus);
nmod_poly_init(quot, modulus);
nmod_poly_init(rem, modulus);
nmod_poly_zero(pol1);
nmod_poly_set_coeff_ui(pol1, 0, 1);
length = n_randint(state, 7) + 2;
do
{
nmod_poly_randtest(poly, state, length);
if (poly->length)
nmod_poly_make_monic(poly, poly);
}
while ((!nmod_poly_is_irreducible(poly)) || (poly->length < 2));
exp[0] = n_randint(state, 30) + 1;
prod1 = exp[0];
for (i = 0; i < exp[0]; i++)
nmod_poly_mul(pol1, pol1, poly);
num = n_randint(state, 5) + 1;
for (i = 1; i < num; i++)
{
do
{
length = n_randint(state, 7) + 2;
nmod_poly_randtest(poly, state, length);
if (poly->length)
{
nmod_poly_make_monic(poly, poly);
nmod_poly_divrem(quot, rem, pol1, poly);
}
}
while ((!nmod_poly_is_irreducible(poly)) ||
(poly->length < 2) || (rem->length == 0));
exp[i] = n_randint(state, 30) + 1;
prod1 *= exp[i];
for (j = 0; j < exp[i]; j++)
nmod_poly_mul(pol1, pol1, poly);
}
nmod_poly_factor_init(res);
switch (n_randint(state, 3))
{
case 0:
lead = nmod_poly_factor(res, pol1);
break;
case 1:
lead = nmod_poly_factor_with_berlekamp(res, pol1);
break;
case 2:
if (modulus == 2)
lead = nmod_poly_factor(res, pol1);
else
lead = nmod_poly_factor_with_cantor_zassenhaus(res, pol1);
break;
}
result &= (res->num == num);
if (!result)
{
printf("Error: number of factors incorrect, %ld, %ld\n",
res->num, num);
abort();
}
nmod_poly_init(product, pol1->mod.n);
nmod_poly_set_coeff_ui(product, 0, 1);
for (i = 0; i < res->num; i++)
for (j = 0; j < res->exp[i]; j++)
nmod_poly_mul(product, product, res->p + i);
nmod_poly_scalar_mul_nmod(product, product, lead);
result &= nmod_poly_equal(pol1, product);
if (!result)
{
printf("Error: product of factors does not equal original polynomial\n");
nmod_poly_print(pol1); printf("\n");
nmod_poly_print(product); printf("\n");
abort();
}
nmod_poly_clear(product);
nmod_poly_clear(quot);
nmod_poly_clear(rem);
nmod_poly_clear(pol1);
nmod_poly_clear(poly);
nmod_poly_factor_clear(res);
}
/* Test deflation trick */
for (iter = 0; iter < 100; iter++)
{
nmod_poly_t pol1, poly, quot, rem;
nmod_poly_factor_t res, res2;
mp_limb_t modulus;
long length, num, i, j;
long exp[5], prod1;
ulong inflation;
int found;
do {
modulus = n_randtest_prime(state, 0);
} while (modulus == 2); /* To compare with CZ */
nmod_poly_init(pol1, modulus);
nmod_poly_init(poly, modulus);
nmod_poly_init(quot, modulus);
nmod_poly_init(rem, modulus);
nmod_poly_zero(pol1);
nmod_poly_set_coeff_ui(pol1, 0, 1);
inflation = n_randint(state, 7) + 1;
length = n_randint(state, 7) + 2;
do
{
nmod_poly_randtest(poly, state, length);
if (poly->length)
nmod_poly_make_monic(poly, poly);
}
while ((!nmod_poly_is_irreducible(poly)) || (poly->length < 2));
nmod_poly_inflate(poly, poly, inflation);
exp[0] = n_randint(state, 6) + 1;
prod1 = exp[0];
for (i = 0; i < exp[0]; i++)
nmod_poly_mul(pol1, pol1, poly);
num = n_randint(state, 5) + 1;
for (i = 1; i < num; i++)
{
do
{
length = n_randint(state, 6) + 2;
nmod_poly_randtest(poly, state, length);
if (poly->length)
{
nmod_poly_make_monic(poly, poly);
nmod_poly_divrem(quot, rem, pol1, poly);
}
}
while ((!nmod_poly_is_irreducible(poly)) ||
(poly->length < 2) || (rem->length == 0));
exp[i] = n_randint(state, 6) + 1;
prod1 *= exp[i];
nmod_poly_inflate(poly, poly, inflation);
for (j = 0; j < exp[i]; j++)
nmod_poly_mul(pol1, pol1, poly);
}
nmod_poly_factor_init(res);
nmod_poly_factor_init(res2);
switch (n_randint(state, 3))
{
case 0:
nmod_poly_factor(res, pol1);
break;
case 1:
nmod_poly_factor_with_berlekamp(res, pol1);
break;
case 2:
nmod_poly_factor_with_cantor_zassenhaus(res, pol1);
break;
}
nmod_poly_factor_cantor_zassenhaus(res2, pol1);
if (res->num != res2->num)
{
printf("FAIL: different number of factors found\n");
abort();
}
for (i = 0; i < res->num; i++)
{
found = 0;
for (j = 0; j < res2->num; j++)
{
if (nmod_poly_equal(res->p + i, res2->p + j) &&
res->exp[i] == res2->exp[j])
{
found = 1;
break;
}
}
if (!found)
{
printf("FAIL: factor not found\n");
abort();
}
}
nmod_poly_clear(quot);
nmod_poly_clear(rem);
nmod_poly_clear(pol1);
nmod_poly_clear(poly);
nmod_poly_factor_clear(res);
nmod_poly_factor_clear(res2);
}
flint_randclear(state);
printf("PASS\n");
return 0;
}
int
main(void)
{
int i, result;
FLINT_TEST_INIT(state);
flint_printf("scalar_mul_nmod....");
fflush(stdout);
/* Check aliasing of a and b */
for (i = 0; i < 1000 * flint_test_multiplier(); i++)
{
nmod_poly_t a, b;
mp_limb_t n = n_randtest_not_zero(state);
mp_limb_t c = n_randint(state, n);
nmod_poly_init(a, n);
nmod_poly_init(b, n);
nmod_poly_randtest(a, state, n_randint(state, 100));
nmod_poly_scalar_mul_nmod(b, a, c);
nmod_poly_scalar_mul_nmod(a, a, c);
result = (nmod_poly_equal(a, b));
if (!result)
{
flint_printf("FAIL:\n");
nmod_poly_print(a), flint_printf("\n\n");
nmod_poly_print(b), flint_printf("\n\n");
abort();
}
nmod_poly_clear(a);
nmod_poly_clear(b);
}
/* Check (a + b)*c = a*c + b*c */
for (i = 0; i < 1000 * flint_test_multiplier(); i++)
{
nmod_poly_t a, b, d1, d2;
mp_limb_t n = n_randtest_not_zero(state);
mp_limb_t c = n_randint(state, n);
nmod_poly_init(a, n);
nmod_poly_init(b, n);
nmod_poly_init(d1, n);
nmod_poly_init(d2, n);
nmod_poly_randtest(a, state, n_randint(state, 100));
nmod_poly_randtest(b, state, n_randint(state, 100));
nmod_poly_add(d1, a, b);
nmod_poly_scalar_mul_nmod(d1, d1, c);
nmod_poly_scalar_mul_nmod(d2, a, c);
nmod_poly_scalar_mul_nmod(b, b, c);
nmod_poly_add(d2, d2, b);
result = (nmod_poly_equal(d1, d2));
if (!result)
{
flint_printf("FAIL:\n");
nmod_poly_print(d1), flint_printf("\n\n");
nmod_poly_print(d2), flint_printf("\n\n");
abort();
}
nmod_poly_clear(a);
nmod_poly_clear(b);
nmod_poly_clear(d1);
nmod_poly_clear(d2);
}
FLINT_TEST_CLEANUP(state);
flint_printf("PASS\n");
return 0;
}
