slong
fmpr_rsqrt(fmpr_t y, const fmpr_t x, slong prec, fmpr_rnd_t rnd)
{
slong r;
if (fmpr_is_special(x))
{
if (fmpr_is_zero(x))
fmpr_pos_inf(y);
else if (fmpr_is_pos_inf(x))
fmpr_zero(y);
else
fmpr_nan(y);
return FMPR_RESULT_EXACT;
}
if (fmpr_sgn(x) < 0)
{
fmpr_nan(y);
return FMPR_RESULT_EXACT;
}
/* special case: 4^n */
if (fmpz_is_one(fmpr_manref(x)) && fmpz_is_even(fmpr_expref(x)))
{
r = fmpr_set_round(y, x, prec, rnd);
fmpz_tdiv_q_2exp(fmpr_expref(y), fmpr_expref(y), 1);
fmpz_neg(fmpr_expref(y), fmpr_expref(y));
return r;
}
{
fmpr_t t;
fmpz_t e;
fmpr_init(t);
fmpz_init(e);
fmpz_neg(e, fmpr_expref(x));
if (fmpz_is_odd(e))
fmpz_add_ui(e, e, 1);
fmpr_mul_2exp_fmpz(t, x, e);
CALL_MPFR_FUNC(r, mpfr_rec_sqrt, y, t, prec, rnd);
fmpz_tdiv_q_2exp(e, e, 1);
fmpr_mul_2exp_fmpz(y, y, e);
fmpr_clear(t);
fmpz_clear(e);
return r;
}
}
int
_fmpz_poly_sqrt_classical(fmpz * res, const fmpz * poly, long len)
{
long i, m;
int result;
/* the degree must be even */
if (len % 2 == 0)
return 0;
/* valuation must be even, and then can be reduced to 0 */
while (fmpz_is_zero(poly))
{
if (!fmpz_is_zero(poly + 1))
return 0;
fmpz_zero(res);
poly += 2;
len -= 2;
res++;
}
/* check whether a square root exists modulo 2 */
for (i = 1; i < len; i += 2)
if (!fmpz_is_even(poly + i))
return 0;
/* check endpoints */
if (!fmpz_is_square(poly) || (len > 1 && !fmpz_is_square(poly + len - 1)))
return 0;
/* square root of leading coefficient */
m = (len + 1) / 2;
fmpz_sqrt(res + m - 1, poly + len - 1);
result = 1;
/* do long divison style 'square root with remainder' from top to bottom */
if (len > 1)
{
fmpz_t t, u;
fmpz * r;
fmpz_init(t);
fmpz_init(u);
r = _fmpz_vec_init(len);
_fmpz_vec_set(r, poly, len);
fmpz_mul_ui(u, res + m - 1, 2);
for (i = 1; i < m; i++)
{
fmpz_fdiv_qr(res + m - i - 1, t, r + len - i - 1, u);
if (!fmpz_is_zero(t))
{
result = 0;
break;
}
fmpz_mul_si(t, res + m - i - 1, -2);
_fmpz_vec_scalar_addmul_fmpz(r + len - 2*i, res + m - i, i - 1, t);
fmpz_submul(r + len - 2*i - 1, res + m - i - 1, res + m - i - 1);
}
for (i = m; i < len && result; i++)
if (!fmpz_is_zero(r + len - 1 - i))
result = 0;
_fmpz_vec_clear(r, len);
fmpz_clear(t);
fmpz_clear(u);
}
return result;
}
void arb_fib_fmpz(arb_t f, const fmpz_t n, slong prec)
{
arb_t t, u;
slong wp, sign, i;
if (fmpz_sgn(n) < 0)
{
fmpz_t m;
fmpz_init(m);
fmpz_neg(m, n);
arb_fib_fmpz(f, m, prec);
if (fmpz_is_even(m))
arb_neg(f, f);
fmpz_clear(m);
return;
}
if (fmpz_cmp_ui(n, 4) <= 0)
{
ulong x = fmpz_get_ui(n);
arb_set_ui(f, x - (x > 1));
return;
}
wp = ARF_PREC_ADD(prec, 3 * fmpz_bits(n));
arb_init(u);
arb_init(t);
arb_set_ui(f, UWORD(1));
arb_set_ui(u, UWORD(1));
sign = -1;
for (i = fmpz_flog_ui(n, UWORD(2)) - 1; i > 0; i--)
{
arb_mul(t, f, f, wp);
arb_add(f, f, u, wp);
arb_mul_2exp_si(f, f, -1);
arb_mul(f, f, f, wp);
arb_mul_2exp_si(f, f, 1);
arb_submul_ui(f, t, 3, wp);
arb_sub_si(f, f, 2 * sign, wp);
arb_mul_ui(u, t, 5, wp);
arb_add_si(u, u, 2 * sign, wp);
sign = 1;
if (fmpz_tstbit(n, i))
{
arb_set(t, f);
arb_add(f, f, u, wp);
arb_mul_2exp_si(f, f, -1);
arb_mul_2exp_si(t, t, 1);
arb_add(u, f, t, wp);
sign = -1;
}
}
if (fmpz_tstbit(n, 0))
{
arb_add(f, f, u, wp);
arb_mul_2exp_si(f, f, -1);
arb_mul(f, f, u, wp);
arb_sub_si(f, f, sign, prec);
}
else
{
arb_mul(f, f, u, prec);
}
arb_clear(u);
arb_clear(t);
}
int
main(void)
{
int iter;
FLINT_TEST_INIT(state);
flint_printf("factor....");
fflush(stdout);
/* Default algorithm */
for (iter = 0; iter < flint_test_multiplier(); iter++)
{
int result = 1;
TEMPLATE(T, poly_t) pol1, poly, quot, rem, product;
TEMPLATE(T, poly_factor_t) res;
TEMPLATE(T, ctx_t) ctx;
TEMPLATE(T, t) lead;
slong length, num, i, j;
ulong exp[5], prod1;
TEMPLATE(T, ctx_randtest) (ctx, state);
TEMPLATE(T, poly_init) (pol1, ctx);
TEMPLATE(T, poly_init) (poly, ctx);
TEMPLATE(T, poly_init) (quot, ctx);
TEMPLATE(T, poly_init) (rem, ctx);
TEMPLATE(T, poly_zero) (pol1, ctx);
TEMPLATE(T, poly_one) (pol1, ctx);
length = n_randint(state, 4) + 2;
TEMPLATE(T, poly_randtest_irreducible) (poly, state, length, ctx);
exp[0] = n_randint(state, 3) + 1;
prod1 = exp[0];
for (i = 0; i < exp[0]; i++)
TEMPLATE(T, poly_mul) (pol1, pol1, poly, ctx);
num = n_randint(state, 3) + 1;
for (i = 1; i < num; i++)
{
do
{
length = n_randint(state, 3) + 2;
TEMPLATE(T, poly_randtest_irreducible) (poly, state, length,
ctx);
TEMPLATE(T, poly_divrem) (quot, rem, pol1, poly, ctx);
}
while ((poly->length < 2) || (rem->length == 0));
exp[i] = n_randint(state, 3) + 1;
prod1 *= exp[i];
for (j = 0; j < exp[i]; j++)
TEMPLATE(T, poly_mul) (pol1, pol1, poly, ctx);
}
TEMPLATE(T, poly_factor_init) (res, ctx);
TEMPLATE(T, init) (lead, ctx);
switch (n_randint(state, 4))
{
case 0:
TEMPLATE(T, poly_factor) (res, lead, pol1, ctx);
break;
case 1:
TEMPLATE(T, poly_factor_with_berlekamp) (res, lead, pol1, ctx);
break;
case 2:
if (fmpz_is_even(TEMPLATE(T, ctx_prime) (ctx)))
TEMPLATE(T, poly_factor) (res, lead, pol1, ctx);
else
TEMPLATE(T, poly_factor_with_cantor_zassenhaus) (res, lead,
pol1,
ctx);
break;
case 3:
TEMPLATE(T, poly_factor_with_kaltofen_shoup) (res, lead, pol1,
ctx);
break;
}
fflush(stdout);
result &= (res->num == num);
if (!result)
{
flint_printf("Error: number of factors incorrect, %wd, %wd\n",
res->num, num);
abort();
}
TEMPLATE(T, poly_init) (product, ctx);
TEMPLATE(T, poly_one) (product, ctx);
for (i = 0; i < res->num; i++)
for (j = 0; j < res->exp[i]; j++)
TEMPLATE(T, poly_mul) (product, product, res->poly + i, ctx);
TEMPLATE(T, TEMPLATE(poly_scalar_mul, T)) (product, product, lead,
ctx);
result &= TEMPLATE(T, poly_equal) (pol1, product, ctx);
if (!result)
{
flint_printf
("Error: product of factors does not equal original polynomial\n");
TEMPLATE(T, poly_print_pretty) (pol1, "x", ctx);
flint_printf("\n");
TEMPLATE(T, poly_print_pretty) (product, "x", ctx);
flint_printf("\n");
abort();
}
TEMPLATE(T, poly_clear) (product, ctx);
TEMPLATE(T, poly_clear) (quot, ctx);
TEMPLATE(T, poly_clear) (rem, ctx);
TEMPLATE(T, poly_clear) (pol1, ctx);
TEMPLATE(T, poly_clear) (poly, ctx);
TEMPLATE(T, poly_factor_clear) (res, ctx);
TEMPLATE(T, clear) (lead, ctx);
TEMPLATE(T, ctx_clear) (ctx);
}
/* Test deflation trick */
for (iter = 0; iter < flint_test_multiplier(); iter++)
{
TEMPLATE(T, poly_t) pol1, poly, quot, rem;
TEMPLATE(T, poly_factor_t) res, res2;
TEMPLATE(T, ctx_t) ctx;
TEMPLATE(T, t) lead;
slong length, num, i, j;
slong exp[5], prod1;
ulong inflation;
int found;
TEMPLATE(T, ctx_randtest) (ctx, state);
TEMPLATE(T, poly_init) (pol1, ctx);
TEMPLATE(T, poly_init) (poly, ctx);
TEMPLATE(T, poly_init) (quot, ctx);
TEMPLATE(T, poly_init) (rem, ctx);
TEMPLATE(T, poly_zero) (pol1, ctx);
TEMPLATE(T, poly_one) (pol1, ctx);
inflation = n_randint(state, 7) + 1;
length = n_randint(state, 4) + 2;
TEMPLATE(T, poly_randtest_irreducible) (poly, state, length, ctx);
TEMPLATE(T, poly_inflate) (poly, poly, inflation, ctx);
exp[0] = n_randint(state, 6) + 1;
prod1 = exp[0];
for (i = 0; i < exp[0]; i++)
TEMPLATE(T, poly_mul) (pol1, pol1, poly, ctx);
num = n_randint(state, 5) + 1;
for (i = 1; i < num; i++)
{
do
{
length = n_randint(state, 6) + 2;
TEMPLATE(T, poly_randtest_irreducible) (poly, state, length,
ctx);
TEMPLATE(T, poly_divrem) (quot, rem, pol1, poly, ctx);
}
while ((poly->length < 2) || (rem->length == 0));
exp[i] = n_randint(state, 6) + 1;
prod1 *= exp[i];
TEMPLATE(T, poly_inflate) (poly, poly, inflation, ctx);
for (j = 0; j < exp[i]; j++)
TEMPLATE(T, poly_mul) (pol1, pol1, poly, ctx);
}
TEMPLATE(T, poly_factor_init) (res, ctx);
TEMPLATE(T, poly_factor_init) (res2, ctx);
TEMPLATE(T, init) (lead, ctx);
switch (n_randint(state, 4))
{
case 0:
TEMPLATE(T, poly_factor) (res, lead, pol1, ctx);
break;
case 1:
TEMPLATE(T, poly_factor_with_berlekamp) (res, lead, pol1, ctx);
break;
case 2:
TEMPLATE(T, poly_factor_with_cantor_zassenhaus) (res, lead,
pol1, ctx);
break;
case 3:
TEMPLATE(T, poly_factor_with_kaltofen_shoup) (res, lead, pol1,
ctx);
break;
}
TEMPLATE(T, poly_factor_cantor_zassenhaus) (res2, pol1, ctx);
if (res->num != res2->num)
{
flint_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 (TEMPLATE(T, poly_equal)
(res->poly + i, res2->poly + j, ctx)
&& res->exp[i] == res2->exp[j])
{
found = 1;
break;
}
}
if (!found)
{
flint_printf("FAIL: factor not found\n");
abort();
}
}
TEMPLATE(T, poly_clear) (quot, ctx);
TEMPLATE(T, poly_clear) (rem, ctx);
TEMPLATE(T, poly_clear) (pol1, ctx);
TEMPLATE(T, poly_clear) (poly, ctx);
TEMPLATE(T, poly_factor_clear) (res, ctx);
TEMPLATE(T, poly_factor_clear) (res2, ctx);
TEMPLATE(T, clear) (lead, ctx);
TEMPLATE(T, ctx_clear) (ctx);
}
FLINT_TEST_CLEANUP(state);
flint_printf("PASS\n");
return 0;
}
