void renf_elem_check_embedding(const renf_elem_t a, const renf_t nf, slong prec)
{
arb_t emb;
arb_init(emb);
if (nf->nf->flag & NF_LINEAR)
{
arb_fmpz_div_fmpz(emb, LNF_ELEM_NUMREF(a->elem), LNF_ELEM_DENREF(a->elem), prec);
}
else if (nf->nf->flag & NF_QUADRATIC)
{
arb_mul_fmpz(emb, nf->emb, QNF_ELEM_NUMREF(a->elem) + 1, prec);
arb_add_fmpz(emb, emb, QNF_ELEM_NUMREF(a->elem), prec);
arb_div_fmpz(emb, emb, QNF_ELEM_DENREF(a->elem), prec);
}
else
{
fmpq_poly_evaluate_arb(emb, NF_ELEM(a->elem), nf->emb, prec);
}
if (!arb_overlaps(a->emb, emb))
{
fprintf(stderr, "embedding set to "); arb_fprint(stderr, a->emb);
fprintf(stderr, " but got "); arb_fprint(stderr, emb); fprintf(stderr, "\n");
arb_clear(emb);
abort();
}
arb_clear(emb);
}
int main()
{
slong iter;
flint_rand_t state;
flint_printf("sin_pi_fmpq....");
fflush(stdout);
flint_randinit(state);
for (iter = 0; iter < 10000 * arb_test_multiplier(); iter++)
{
arb_t s1, s2;
fmpq_t x;
slong prec;
prec = 2 + n_randint(state, 5000);
arb_init(s1);
arb_init(s2);
fmpq_init(x);
fmpq_randtest(x, state, 1 + n_randint(state, 200));
arb_sin_pi_fmpq(s1, x, prec);
arb_const_pi(s2, prec);
arb_mul_fmpz(s2, s2, fmpq_numref(x), prec);
arb_div_fmpz(s2, s2, fmpq_denref(x), prec);
arb_sin(s2, s2, prec);
if (!arb_overlaps(s1, s2))
{
flint_printf("FAIL: overlap\n\n");
flint_printf("x = "); fmpq_print(x); flint_printf("\n\n");
flint_printf("s1 = "); arb_printd(s1, 15); flint_printf("\n\n");
flint_printf("s2 = "); arb_printd(s2, 15); flint_printf("\n\n");
abort();
}
arb_clear(s1);
arb_clear(s2);
fmpq_clear(x);
}
flint_randclear(state);
flint_cleanup();
flint_printf("PASS\n");
return EXIT_SUCCESS;
}
void
_arb_cos_pi_fmpq_oct(arb_t c, const fmpz_t v, const fmpz_t w, slong prec)
{
if (use_algebraic(v, w, prec))
{
_arb_cos_pi_fmpq_algebraic(c, *v, *w, prec);
}
else
{
arb_const_pi(c, prec);
arb_mul_fmpz(c, c, v, prec);
arb_div_fmpz(c, c, w, prec);
arb_cos(c, c, prec);
}
}
void
_arb_sin_pi_fmpq_oct(arb_t s, const fmpz_t v, const fmpz_t w, slong prec)
{
if (use_algebraic(v, w, prec))
{
_arb_sin_pi_fmpq_algebraic(s, *v, *w, prec);
}
else
{
arb_const_pi(s, prec);
arb_mul_fmpz(s, s, v, prec);
arb_div_fmpz(s, s, w, prec);
arb_sin(s, s, prec);
}
}
void
arb_bernoulli_fmpz(arb_t res, const fmpz_t n, slong prec)
{
if (fmpz_cmp_ui(n, UWORD_MAX) <= 0)
{
if (fmpz_sgn(n) >= 0)
arb_bernoulli_ui(res, fmpz_get_ui(n), prec);
else
arb_zero(res);
}
else if (fmpz_is_odd(n))
{
arb_zero(res);
}
else
{
arb_t t;
slong wp;
arb_init(t);
wp = prec + 2 * fmpz_bits(n);
/* zeta(n) ~= 1 */
arf_one(arb_midref(res));
mag_one(arb_radref(res));
mag_mul_2exp_si(arb_radref(res), arb_radref(res), WORD_MIN);
/* |B_n| = 2 * n! / (2*pi)^n * zeta(n) */
arb_gamma_fmpz(t, n, wp);
arb_mul_fmpz(t, t, n, wp);
arb_mul(res, res, t, wp);
arb_const_pi(t, wp);
arb_mul_2exp_si(t, t, 1);
arb_pow_fmpz(t, t, n, wp);
arb_div(res, res, t, prec);
arb_mul_2exp_si(res, res, 1);
if (fmpz_fdiv_ui(n, 4) == 0)
arb_neg(res, res);
arb_clear(t);
}
}
void
arb_pow_fmpq(arb_t y, const arb_t x, const fmpq_t a, long prec)
{
if (fmpz_is_one(fmpq_denref(a)))
{
arb_pow_fmpz(y, x, fmpq_numref(a), prec);
}
else if (fmpz_cmp_ui(fmpq_denref(a), 36) <= 0)
{
arb_root(y, x, *fmpq_denref(a), prec);
arb_pow_fmpz(y, y, fmpq_numref(a), prec);
}
else
{
long wp;
wp = prec + 10;
arb_log(y, x, wp);
arb_mul_fmpz(y, y, fmpq_numref(a), wp);
arb_div_fmpz(y, y, fmpq_denref(a), wp);
arb_exp(y, y, prec);
}
}
int main()
{
slong iter;
flint_rand_t state;
flint_printf("mul_fmpz....");
fflush(stdout);
flint_randinit(state);
for (iter = 0; iter < 10000 * arb_test_multiplier(); iter++)
{
arb_t a, b, c, d;
fmpz_t x;
slong prec;
arb_init(a);
arb_init(b);
arb_init(c);
arb_init(d);
fmpz_init(x);
arb_randtest_special(a, state, 1 + n_randint(state, 2000), 100);
arb_randtest_special(b, state, 1 + n_randint(state, 2000), 100);
arb_randtest_special(c, state, 1 + n_randint(state, 2000), 100);
fmpz_randtest(x, state, 1 + n_randint(state, 2000));
prec = 2 + n_randint(state, 2000);
arb_set_fmpz(b, x);
arb_mul_fmpz(c, a, x, prec);
arb_mul(d, a, b, prec);
if (!arb_equal(c, d))
{
flint_printf("FAIL\n\n");
flint_printf("a = "); arb_print(a); flint_printf("\n\n");
flint_printf("b = "); arb_print(b); flint_printf("\n\n");
flint_printf("c = "); arb_print(c); flint_printf("\n\n");
flint_printf("d = "); arb_print(d); flint_printf("\n\n");
abort();
}
arb_clear(a);
arb_clear(b);
arb_clear(c);
arb_clear(d);
fmpz_clear(x);
}
/* aliasing */
for (iter = 0; iter < 10000 * arb_test_multiplier(); iter++)
{
arb_t a, b, c;
fmpz_t x;
slong prec;
arb_init(a);
arb_init(b);
arb_init(c);
fmpz_init(x);
arb_randtest_special(a, state, 1 + n_randint(state, 2000), 100);
arb_randtest_special(b, state, 1 + n_randint(state, 2000), 100);
arb_randtest_special(c, state, 1 + n_randint(state, 2000), 100);
fmpz_randtest(x, state, 1 + n_randint(state, 2000));
prec = 2 + n_randint(state, 2000);
arb_set_fmpz(b, x);
arb_mul_fmpz(c, a, x, prec);
arb_mul_fmpz(a, a, x, prec);
if (!arb_equal(a, c))
{
flint_printf("FAIL (aliasing)\n\n");
flint_printf("a = "); arb_print(a); flint_printf("\n\n");
flint_printf("b = "); arb_print(b); flint_printf("\n\n");
flint_printf("c = "); arb_print(c); flint_printf("\n\n");
abort();
}
arb_clear(a);
arb_clear(b);
arb_clear(c);
fmpz_clear(x);
}
flint_randclear(state);
flint_cleanup();
flint_printf("PASS\n");
return EXIT_SUCCESS;
}
int main()
{
slong iter;
flint_rand_t state;
flint_printf("get_mpn_fixed_mod_pi4....");
fflush(stdout);
flint_randinit(state);
/* _flint_rand_init_gmp(state); */
for (iter = 0; iter < 100000 * arb_test_multiplier(); iter++)
{
arf_t x;
int octant;
fmpz_t q;
mp_ptr w;
arb_t wb, t, u;
mp_size_t wn;
slong prec, prec2;
int success;
mp_limb_t error;
prec = 2 + n_randint(state, 10000);
wn = 1 + n_randint(state, 200);
prec2 = FLINT_MAX(prec, wn * FLINT_BITS) + 100;
arf_init(x);
arb_init(wb);
arb_init(t);
arb_init(u);
fmpz_init(q);
w = flint_malloc(sizeof(mp_limb_t) * wn);
arf_randtest(x, state, prec, 14);
/* this should generate numbers close to multiples of pi/4 */
if (n_randint(state, 4) == 0)
{
arb_const_pi(t, prec);
arb_mul_2exp_si(t, t, -2);
fmpz_randtest(q, state, 200);
arb_mul_fmpz(t, t, q, prec);
arf_add(x, x, arb_midref(t), prec, ARF_RND_DOWN);
}
arf_abs(x, x);
success = _arb_get_mpn_fixed_mod_pi4(w, q, &octant, &error, x, wn);
if (success)
{
/* could round differently */
if (fmpz_fdiv_ui(q, 8) != octant)
{
flint_printf("bad octant\n");
abort();
}
_arf_set_mpn_fixed(arb_midref(wb), w, wn, wn, 0, FLINT_BITS * wn, ARB_RND);
mag_set_ui_2exp_si(arb_radref(wb), error, -FLINT_BITS * wn);
arb_const_pi(u, prec2);
arb_mul_2exp_si(u, u, -2);
arb_set(t, wb);
if (octant % 2 == 1)
arb_sub(t, u, t, prec2);
arb_addmul_fmpz(t, u, q, prec2);
if (!arb_contains_arf(t, x))
{
flint_printf("FAIL (containment)\n");
flint_printf("x = "); arf_printd(x, 50); flint_printf("\n\n");
flint_printf("q = "); fmpz_print(q); flint_printf("\n\n");
flint_printf("w = "); arb_printd(wb, 50); flint_printf("\n\n");
flint_printf("t = "); arb_printd(t, 50); flint_printf("\n\n");
abort();
}
arb_const_pi(t, prec2);
arb_mul_2exp_si(t, t, -2);
if (arf_sgn(arb_midref(wb)) < 0 ||
arf_cmp(arb_midref(wb), arb_midref(t)) >= 0)
{
flint_printf("FAIL (expected 0 <= w < pi/4)\n");
flint_printf("x = "); arf_printd(x, 50); flint_printf("\n\n");
flint_printf("w = "); arb_printd(wb, 50); flint_printf("\n\n");
abort();
}
}
flint_free(w);
fmpz_clear(q);
arf_clear(x);
arb_clear(wb);
arb_clear(t);
arb_clear(u);
}
flint_randclear(state);
flint_cleanup();
flint_printf("PASS\n");
return EXIT_SUCCESS;
}
void
_arb_bell_sum_taylor(arb_t res, const fmpz_t n,
const fmpz_t a, const fmpz_t b, const fmpz_t mmag, long tol)
{
fmpz_t m, r, R, tmp;
mag_t B, C, D, bound;
arb_t t, u;
long wp, k, N;
if (_fmpz_sub_small(b, a) < 5)
{
arb_bell_sum_bsplit(res, n, a, b, mmag, tol);
return;
}
fmpz_init(m);
fmpz_init(r);
fmpz_init(R);
fmpz_init(tmp);
/* r = max(m - a, b - m) */
/* m = a + (b - a) / 2 */
fmpz_sub(r, b, a);
fmpz_cdiv_q_2exp(r, r, 1);
fmpz_add(m, a, r);
fmpz_mul_2exp(R, r, RADIUS_BITS);
mag_init(B);
mag_init(C);
mag_init(D);
mag_init(bound);
arb_init(t);
arb_init(u);
if (fmpz_cmp(R, m) >= 0)
{
mag_inf(C);
mag_inf(D);
}
else
{
/* C = exp(R * |F'(m)| + (1/2) R^2 * (n/(m-R)^2 + 1/(m-R))) */
/* C = exp(R * (|F'(m)| + (1/2) R * (n/(m-R) + 1)/(m-R))) */
/* D = (1/2) R * (n/(m-R) + 1)/(m-R) */
fmpz_sub(tmp, m, R);
mag_set_fmpz(D, n);
mag_div_fmpz(D, D, tmp);
mag_one(C);
mag_add(D, D, C);
mag_div_fmpz(D, D, tmp);
mag_mul_fmpz(D, D, R);
mag_mul_2exp_si(D, D, -1);
/* C = |F'(m)| */
wp = 20 + 1.05 * fmpz_bits(n);
arb_set_fmpz(t, n);
arb_div_fmpz(t, t, m, wp);
fmpz_add_ui(tmp, m, 1);
arb_set_fmpz(u, tmp);
arb_digamma(u, u, wp);
arb_sub(t, t, u, wp);
arb_get_mag(C, t);
/* C = exp(R * (C + D)) */
mag_add(C, C, D);
mag_mul_fmpz(C, C, R);
mag_exp(C, C);
}
if (mag_cmp_2exp_si(C, tol / 4 + 2) > 0)
{
_arb_bell_sum_taylor(res, n, a, m, mmag, tol);
_arb_bell_sum_taylor(t, n, m, b, mmag, tol);
arb_add(res, res, t, 2 * tol);
}
else
{
arb_ptr mx, ser1, ser2, ser3;
/* D = T(m) */
wp = 20 + 1.05 * fmpz_bits(n);
arb_set_fmpz(t, m);
arb_pow_fmpz(t, t, n, wp);
fmpz_add_ui(tmp, m, 1);
arb_gamma_fmpz(u, tmp, wp);
arb_div(t, t, u, wp);
arb_get_mag(D, t);
/* error bound: (b-a) * C * D * B^N / (1 - B), B = r/R */
/* ((b-a) * C * D * 2) * 2^(-N*RADIUS_BITS) */
/* ((b-a) * C * D * 2) */
mag_mul(bound, C, D);
mag_mul_2exp_si(bound, bound, 1);
fmpz_sub(tmp, b, a);
mag_mul_fmpz(bound, bound, tmp);
/* N = (tol + log2((b-a)*C*D*2) - mmag) / RADIUS_BITS */
if (mmag == NULL)
{
/* estimate D ~= 2^mmag */
fmpz_add_ui(tmp, MAG_EXPREF(C), tol);
fmpz_cdiv_q_ui(tmp, tmp, RADIUS_BITS);
}
else
{
fmpz_sub(tmp, MAG_EXPREF(bound), mmag);
fmpz_add_ui(tmp, tmp, tol);
fmpz_cdiv_q_ui(tmp, tmp, RADIUS_BITS);
}
if (fmpz_cmp_ui(tmp, 5 * tol / 4) > 0)
N = 5 * tol / 4;
else if (fmpz_cmp_ui(tmp, 2) < 0)
N = 2;
else
N = fmpz_get_ui(tmp);
/* multiply by 2^(-N*RADIUS_BITS) */
mag_mul_2exp_si(bound, bound, -N * RADIUS_BITS);
mx = _arb_vec_init(2);
ser1 = _arb_vec_init(N);
ser2 = _arb_vec_init(N);
ser3 = _arb_vec_init(N);
/* estimate (this should work for moderate n and tol) */
wp = 1.1 * tol + 1.05 * fmpz_bits(n) + 5;
/* increase precision until convergence */
while (1)
{
/* (m+x)^n / gamma(m+1+x) */
arb_set_fmpz(mx, m);
arb_one(mx + 1);
_arb_poly_log_series(ser1, mx, 2, N, wp);
for (k = 0; k < N; k++)
arb_mul_fmpz(ser1 + k, ser1 + k, n, wp);
arb_add_ui(mx, mx, 1, wp);
_arb_poly_lgamma_series(ser2, mx, 2, N, wp);
_arb_vec_sub(ser1, ser1, ser2, N, wp);
_arb_poly_exp_series(ser3, ser1, N, N, wp);
/* t = a - m, u = b - m */
arb_set_fmpz(t, a);
arb_sub_fmpz(t, t, m, wp);
arb_set_fmpz(u, b);
arb_sub_fmpz(u, u, m, wp);
arb_power_sum_vec(ser1, t, u, N, wp);
arb_zero(res);
for (k = 0; k < N; k++)
arb_addmul(res, ser3 + k, ser1 + k, wp);
if (mmag != NULL)
{
if (_fmpz_sub_small(MAG_EXPREF(arb_radref(res)), mmag) <= -tol)
break;
}
else
{
if (arb_rel_accuracy_bits(res) >= tol)
break;
}
wp = 2 * wp;
}
/* add the series truncation bound */
arb_add_error_mag(res, bound);
_arb_vec_clear(mx, 2);
_arb_vec_clear(ser1, N);
_arb_vec_clear(ser2, N);
_arb_vec_clear(ser3, N);
}
mag_clear(B);
mag_clear(C);
mag_clear(D);
mag_clear(bound);
arb_clear(t);
arb_clear(u);
fmpz_clear(m);
fmpz_clear(r);
fmpz_clear(R);
fmpz_clear(tmp);
}
/* corrects branch cut of sum_{k=0}^{r-1} log(z+k), given the
logarithm of the product */
void
_acb_log_rising_correct_branch(acb_t t,
const acb_t t_wrong, const acb_t z, ulong r, long prec)
{
acb_t f;
arb_t pi, u, v;
fmpz_t pi_mult;
long i, argprec;
acb_init(f);
arb_init(u);
arb_init(pi);
arb_init(v);
fmpz_init(pi_mult);
argprec = FLINT_MIN(prec, 40);
arb_zero(u);
for (i = 0; i < r; i++)
{
acb_add_ui(f, z, i, argprec);
acb_arg(v, f, argprec);
arb_add(u, u, v, argprec);
}
if (argprec == prec)
{
arb_set(acb_imagref(t), u);
}
else
{
arb_sub(v, u, acb_imagref(t), argprec);
arb_const_pi(pi, argprec);
arb_div(v, v, pi, argprec);
if (arb_get_unique_fmpz(pi_mult, v))
{
arb_const_pi(v, prec);
arb_mul_fmpz(v, v, pi_mult, prec);
arb_add(acb_imagref(t), acb_imagref(t), v, prec);
}
else
{
arb_zero(u);
for (i = 0; i < r; i++)
{
acb_add_ui(f, z, i, prec);
acb_arg(v, f, prec);
arb_add(u, u, v, prec);
}
arb_set(acb_imagref(t), u);
}
}
acb_clear(f);
arb_clear(u);
arb_clear(v);
arb_clear(pi);
fmpz_clear(pi_mult);
}
void acb_modular_transform(acb_t w, const psl2z_t g, const acb_t z, slong prec)
{
#define a (&g->a)
#define b (&g->b)
#define c (&g->c)
#define d (&g->d)
#define x acb_realref(z)
#define y acb_imagref(z)
if (fmpz_is_zero(c))
{
/* (az+b)/d, where we must have a = d = 1 */
acb_add_fmpz(w, z, b, prec);
}
else if (fmpz_is_zero(a))
{
/* b/(cz+d), where -bc = 1, c = 1 => -1/(z+d) */
acb_add_fmpz(w, z, d, prec);
acb_inv(w, w, prec);
acb_neg(w, w);
}
else if (0)
{
acb_t t, u;
acb_init(t);
acb_init(u);
acb_set_fmpz(t, b);
acb_addmul_fmpz(t, z, a, prec);
acb_set_fmpz(u, d);
acb_addmul_fmpz(u, z, c, prec);
acb_div(w, t, u, prec);
acb_clear(t);
acb_clear(u);
}
else
{
/* (az+b)/(cz+d) = (re+im*i)/den where
re = bd + (bc+ad)x + ac(x^2+y^2)
im = (ad-bc)y
den = c^2(x^2+y^2) + 2cdx + d^2
*/
fmpz_t t;
arb_t re, im, den;
arb_init(re);
arb_init(im);
arb_init(den);
fmpz_init(t);
arb_mul(im, x, x, prec);
arb_addmul(im, y, y, prec);
fmpz_mul(t, b, d);
arb_set_fmpz(re, t);
fmpz_mul(t, b, c);
fmpz_addmul(t, a, d);
arb_addmul_fmpz(re, x, t, prec);
fmpz_mul(t, a, c);
arb_addmul_fmpz(re, im, t, prec);
fmpz_mul(t, d, d);
arb_set_fmpz(den, t);
fmpz_mul(t, c, d);
fmpz_mul_2exp(t, t, 1);
arb_addmul_fmpz(den, x, t, prec);
fmpz_mul(t, c, c);
arb_addmul_fmpz(den, im, t, prec);
fmpz_mul(t, a, d);
fmpz_submul(t, b, c);
arb_mul_fmpz(im, y, t, prec);
arb_div(acb_realref(w), re, den, prec);
arb_div(acb_imagref(w), im, den, prec);
arb_clear(re);
arb_clear(im);
arb_clear(den);
fmpz_clear(t);
}
#undef a
#undef b
#undef c
#undef d
#undef x
#undef y
}
void
arb_log_arf(arb_t z, const arf_t x, slong prec)
{
if (arf_is_special(x))
{
if (arf_is_pos_inf(x))
arb_pos_inf(z);
else
arb_indeterminate(z);
}
else if (ARF_SGNBIT(x))
{
arb_indeterminate(z);
}
else if (ARF_IS_POW2(x))
{
if (fmpz_is_one(ARF_EXPREF(x)))
{
arb_zero(z);
}
else
{
fmpz_t exp;
fmpz_init(exp);
_fmpz_add_fast(exp, ARF_EXPREF(x), -1);
arb_const_log2(z, prec + 2);
arb_mul_fmpz(z, z, exp, prec);
fmpz_clear(exp);
}
}
else if (COEFF_IS_MPZ(*ARF_EXPREF(x)))
{
arb_log_arf_huge(z, x, prec);
}
else
{
slong exp, wp, wn, N, r, closeness_to_one;
mp_srcptr xp;
mp_size_t xn, tn;
mp_ptr tmp, w, t, u;
mp_limb_t p1, q1bits, p2, q2bits, error, error2, cy;
int negative, inexact, used_taylor_series;
TMP_INIT;
exp = ARF_EXP(x);
negative = 0;
ARF_GET_MPN_READONLY(xp, xn, x);
/* compute a c >= 0 such that |x-1| <= 2^(-c) if c > 0 */
closeness_to_one = 0;
if (exp == 0)
{
slong i;
closeness_to_one = FLINT_BITS - FLINT_BIT_COUNT(~xp[xn - 1]);
if (closeness_to_one == FLINT_BITS)
{
for (i = xn - 2; i > 0 && xp[i] == LIMB_ONES; i--)
closeness_to_one += FLINT_BITS;
closeness_to_one += (FLINT_BITS - FLINT_BIT_COUNT(~xp[i]));
}
}
else if (exp == 1)
{
closeness_to_one = FLINT_BITS - FLINT_BIT_COUNT(xp[xn - 1] & (~LIMB_TOP));
if (closeness_to_one == FLINT_BITS)
{
slong i;
for (i = xn - 2; xp[i] == 0; i--)
closeness_to_one += FLINT_BITS;
closeness_to_one += (FLINT_BITS - FLINT_BIT_COUNT(xp[i]));
}
closeness_to_one--;
}
/* if |t-1| <= 0.5 */
/* |log(1+t) - t| <= t^2 */
/* |log(1+t) - (t-t^2/2)| <= t^3 */
if (closeness_to_one > prec + 1)
{
inexact = arf_sub_ui(arb_midref(z), x, 1, prec, ARB_RND);
mag_set_ui_2exp_si(arb_radref(z), 1, -2 * closeness_to_one);
if (inexact)
arf_mag_add_ulp(arb_radref(z), arb_radref(z), arb_midref(z), prec);
return;
}
else if (2 * closeness_to_one > prec + 1)
{
arf_t t, u;
arf_init(t);
arf_init(u);
arf_sub_ui(t, x, 1, ARF_PREC_EXACT, ARF_RND_DOWN);
arf_mul(u, t, t, ARF_PREC_EXACT, ARF_RND_DOWN);
arf_mul_2exp_si(u, u, -1);
inexact = arf_sub(arb_midref(z), t, u, prec, ARB_RND);
mag_set_ui_2exp_si(arb_radref(z), 1, -3 * closeness_to_one);
if (inexact)
arf_mag_add_ulp(arb_radref(z), arb_radref(z), arb_midref(z), prec);
arf_clear(t);
arf_clear(u);
return;
}
/* Absolute working precision (NOT rounded to a limb multiple) */
wp = prec + closeness_to_one + 5;
/* Too high precision to use table */
if (wp > ARB_LOG_TAB2_PREC)
{
arf_log_via_mpfr(arb_midref(z), x, prec, ARB_RND);
arf_mag_set_ulp(arb_radref(z), arb_midref(z), prec);
return;
}
/* Working precision in limbs */
wn = (wp + FLINT_BITS - 1) / FLINT_BITS;
TMP_START;
tmp = TMP_ALLOC_LIMBS(4 * wn + 3);
w = tmp; /* requires wn+1 limbs */
t = w + wn + 1; /* requires wn+1 limbs */
u = t + wn + 1; /* requires 2wn+1 limbs */
/* read x-1 */
if (xn <= wn)
{
flint_mpn_zero(w, wn - xn);
mpn_lshift(w + wn - xn, xp, xn, 1);
error = 0;
}
else
{
mpn_lshift(w, xp + xn - wn, wn, 1);
error = 1;
}
/* First table-based argument reduction */
if (wp <= ARB_LOG_TAB1_PREC)
q1bits = ARB_LOG_TAB11_BITS;
else
q1bits = ARB_LOG_TAB21_BITS;
p1 = w[wn-1] >> (FLINT_BITS - q1bits);
/* Special case: covers logarithms of small integers */
if (xn == 1 && (w[wn-1] == (p1 << (FLINT_BITS - q1bits))))
{
p2 = 0;
flint_mpn_zero(t, wn);
used_taylor_series = 0;
N = r = 0; /* silence compiler warning */
}
else
{
/* log(1+w) = log(1+p/q) + log(1 + (qw-p)/(p+q)) */
w[wn] = mpn_mul_1(w, w, wn, UWORD(1) << q1bits) - p1;
mpn_divrem_1(w, 0, w, wn + 1, p1 + (UWORD(1) << q1bits));
error += 1;
/* Second table-based argument reduction (fused with log->atanh
conversion) */
if (wp <= ARB_LOG_TAB1_PREC)
q2bits = ARB_LOG_TAB11_BITS + ARB_LOG_TAB12_BITS;
else
q2bits = ARB_LOG_TAB21_BITS + ARB_LOG_TAB22_BITS;
p2 = w[wn-1] >> (FLINT_BITS - q2bits);
u[2 * wn] = mpn_lshift(u + wn, w, wn, q2bits);
flint_mpn_zero(u, wn);
flint_mpn_copyi(t, u + wn, wn + 1);
t[wn] += p2 + (UWORD(1) << (q2bits + 1));
u[2 * wn] -= p2;
mpn_tdiv_q(w, u, 2 * wn + 1, t, wn + 1);
/* propagated error from 1 ulp error: 2 atanh'(1/3) = 2.25 */
error += 3;
/* |w| <= 2^-r */
r = _arb_mpn_leading_zeros(w, wn);
/* N >= (wp-r)/(2r) */
N = (wp - r + (2*r-1)) / (2*r);
N = FLINT_MAX(N, 0);
/* Evaluate Taylor series */
_arb_atan_taylor_rs(t, &error2, w, wn, N, 0);
/* Multiply by 2 */
mpn_lshift(t, t, wn, 1);
/* Taylor series evaluation error (multiply by 2) */
error += error2 * 2;
used_taylor_series = 1;
}
/* Size of output number */
tn = wn;
/* First table lookup */
if (p1 != 0)
{
if (wp <= ARB_LOG_TAB1_PREC)
mpn_add_n(t, t, arb_log_tab11[p1] + ARB_LOG_TAB1_LIMBS - tn, tn);
else
mpn_add_n(t, t, arb_log_tab21[p1] + ARB_LOG_TAB2_LIMBS - tn, tn);
error++;
}
/* Second table lookup */
if (p2 != 0)
{
if (wp <= ARB_LOG_TAB1_PREC)
mpn_add_n(t, t, arb_log_tab12[p2] + ARB_LOG_TAB1_LIMBS - tn, tn);
else
mpn_add_n(t, t, arb_log_tab22[p2] + ARB_LOG_TAB2_LIMBS - tn, tn);
error++;
}
/* add exp * log(2) */
exp--;
if (exp > 0)
{
cy = mpn_addmul_1(t, arb_log_log2_tab + ARB_LOG_TAB2_LIMBS - tn, tn, exp);
t[tn] = cy;
tn += (cy != 0);
error += exp;
}
else if (exp < 0)
{
t[tn] = 0;
u[tn] = mpn_mul_1(u, arb_log_log2_tab + ARB_LOG_TAB2_LIMBS - tn, tn, -exp);
if (mpn_cmp(t, u, tn + 1) >= 0)
{
mpn_sub_n(t, t, u, tn + 1);
}
else
{
mpn_sub_n(t, u, t, tn + 1);
negative = 1;
}
error += (-exp);
tn += (t[tn] != 0);
}
/* The accumulated arithmetic error */
mag_set_ui_2exp_si(arb_radref(z), error, -wn * FLINT_BITS);
/* Truncation error from the Taylor series */
if (used_taylor_series)
mag_add_ui_2exp_si(arb_radref(z), arb_radref(z), 1, -r*(2*N+1) + 1);
/* Set the midpoint */
inexact = _arf_set_mpn_fixed(arb_midref(z), t, tn, wn, negative, prec);
if (inexact)
arf_mag_add_ulp(arb_radref(z), arb_radref(z), arb_midref(z), prec);
TMP_END;
}
}
