void
_arb_poly_revert_series_lagrange_fast(arb_ptr Qinv, arb_srcptr Q, long Qlen, long n, long prec)
{
long i, j, k, m;
arb_ptr R, S, T, tmp;
arb_t t;
if (n <= 2)
{
if (n >= 1)
arb_zero(Qinv);
if (n == 2)
arb_inv(Qinv + 1, Q + 1, prec);
return;
}
m = n_sqrt(n);
arb_init(t);
R = _arb_vec_init((n - 1) * m);
S = _arb_vec_init(n - 1);
T = _arb_vec_init(n - 1);
arb_zero(Qinv);
arb_inv(Qinv + 1, Q + 1, prec);
_arb_poly_inv_series(Ri(1), Q + 1, FLINT_MIN(Qlen, n) - 1, n - 1, prec);
for (i = 2; i <= m; i++)
_arb_poly_mullow(Ri(i), Ri((i + 1) / 2), n - 1, Ri(i / 2), n - 1, n - 1, prec);
for (i = 2; i < m; i++)
arb_div_ui(Qinv + i, Ri(i) + i - 1, i, prec);
_arb_vec_set(S, Ri(m), n - 1);
for (i = m; i < n; i += m)
{
arb_div_ui(Qinv + i, S + i - 1, i, prec);
for (j = 1; j < m && i + j < n; j++)
{
arb_mul(t, S + 0, Ri(j) + i + j - 1, prec);
for (k = 1; k <= i + j - 1; k++)
arb_addmul(t, S + k, Ri(j) + i + j - 1 - k, prec);
arb_div_ui(Qinv + i + j, t, i + j, prec);
}
if (i + 1 < n)
{
_arb_poly_mullow(T, S, n - 1, Ri(m), n - 1, n - 1, prec);
tmp = S; S = T; T = tmp;
}
}
arb_clear(t);
_arb_vec_clear(R, (n - 1) * m);
_arb_vec_clear(S, n - 1);
_arb_vec_clear(T, n - 1);
}
int
f_pol(arb_t max, const arb_t t, params_t * p, slong prec)
{
slong k;
acb_t z;
arb_t tmp;
acb_init(z);
arb_init(tmp);
arb_one(max);
for (k = 0; k < p->len; k++)
{
acb_sub_arb(z, p->z + k, t, prec);
acb_abs(tmp, z, prec);
if (arb_contains_zero(tmp))
return 0;
arb_mul(max, max, tmp, prec);
}
arb_inv(max, max, prec);
arb_clear(tmp);
acb_clear(z);
return 1;
}
void
arb_sech(arb_t res, const arb_t x, slong prec)
{
if (arf_cmpabs_2exp_si(arb_midref(x), 0) > 0)
{
arb_t t;
arb_init(t);
if (arf_sgn(arb_midref(x)) > 0)
{
arb_neg(t, x);
arb_exp(t, t, prec + 4);
}
else
{
arb_exp(t, x, prec + 4);
}
arb_mul(res, t, t, prec + 4);
arb_add_ui(res, res, 1, prec + 4);
arb_div(res, t, res, prec);
arb_mul_2exp_si(res, res, 1);
arb_clear(t);
}
else
{
arb_cosh(res, x, prec + 4);
arb_inv(res, res, prec);
}
}
void
custom_rate_mixture_get_prob(arb_t prob, const custom_rate_mixture_t x,
slong idx, slong prec)
{
if (x->mode == RATE_MIXTURE_UNDEFINED)
{
flint_fprintf(stderr, "internal error: undefined rate mixture\n");
abort();
}
else if (x->mode == RATE_MIXTURE_NONE)
{
arb_one(prob);
}
else if (x->mode == RATE_MIXTURE_UNIFORM)
{
/*
* This code branch involves a division that could
* unnecessarily lose exactness in some situations.
*/
arb_set_si(prob, x->n);
arb_inv(prob, prob, prec);
}
else if (x->mode == RATE_MIXTURE_CUSTOM)
{
arb_set_d(prob, x->prior[idx]);
}
else
{
flint_fprintf(stderr, "internal error: "
"unrecognized rate mixture mode\n");
abort();
}
}
int main()
{
slong iter;
flint_rand_t state;
flint_printf("csch....");
fflush(stdout);
flint_randinit(state);
for (iter = 0; iter < 1000 * arb_test_multiplier(); iter++)
{
arb_t x, a, b;
slong prec1, prec2;
prec1 = 2 + n_randint(state, 200);
prec2 = prec1 + 30;
arb_init(x);
arb_init(a);
arb_init(b);
arb_randtest_special(x, state, 1 + n_randint(state, 300), 100);
arb_randtest_special(a, state, 1 + n_randint(state, 300), 100);
arb_randtest_special(b, state, 1 + n_randint(state, 300), 100);
if (n_randint(state, 2))
{
arb_csch(a, x, prec1);
}
else
{
arb_set(a, x);
arb_csch(a, a, prec1);
}
arb_sinh(b, x, prec2);
arb_inv(b, b, prec2);
/* check consistency */
if (!arb_overlaps(a, b))
{
flint_printf("FAIL: overlap\n\n");
flint_printf("x = "); arb_printn(x, 20, 0); flint_printf("\n\n");
flint_printf("a = "); arb_printn(a, 20, 0); flint_printf("\n\n");
flint_printf("b = "); arb_printn(b, 20, 0); flint_printf("\n\n");
flint_abort();
}
arb_clear(x);
arb_clear(a);
arb_clear(b);
}
flint_randclear(state);
flint_cleanup();
flint_printf("PASS\n");
return EXIT_SUCCESS;
}
int
f_1x2(arb_t max, const arb_t t, params_t * p, slong prec)
{
arb_mul(max, t, t, prec);
arb_add_si(max, max, 1, prec);
arb_inv(max, max, prec);
return 1;
}
int main()
{
slong iter;
flint_rand_t state;
flint_printf("rsqrt....");
fflush(stdout);
flint_randinit(state);
for (iter = 0; iter < 100000; iter++)
{
arb_t a, b, c;
slong prec = 2 + n_randint(state, 200);
arb_init(a);
arb_init(b);
arb_init(c);
arb_randtest(a, state, 1 + n_randint(state, 200), 10);
arb_rsqrt(b, a, prec);
arb_inv(c, b, prec);
arb_mul(c, c, c, prec);
if (!arb_contains(c, a))
{
flint_printf("FAIL: containment\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_rsqrt(a, a, prec);
if (!arb_equal(a, b))
{
flint_printf("FAIL: aliasing\n\n");
abort();
}
arb_clear(a);
arb_clear(b);
arb_clear(c);
}
flint_randclear(state);
flint_cleanup();
flint_printf("PASS\n");
return EXIT_SUCCESS;
}
static void
bound_I(arb_ptr I, const arb_t A, const arb_t B, const arb_t C, slong len, slong wp)
{
slong k;
arb_t D, Dk, L, T, Bm1;
arb_init(D);
arb_init(Dk);
arb_init(Bm1);
arb_init(T);
arb_init(L);
arb_sub_ui(Bm1, B, 1, wp);
arb_one(L);
/* T = 1 / (A^Bm1 * Bm1) */
arb_inv(T, A, wp);
arb_pow(T, T, Bm1, wp);
arb_div(T, T, Bm1, wp);
if (len > 1)
{
arb_log(D, A, wp);
arb_add(D, D, C, wp);
arb_mul(D, D, Bm1, wp);
arb_set(Dk, D);
}
for (k = 0; k < len; k++)
{
if (k > 0)
{
arb_mul_ui(L, L, k, wp);
arb_add(L, L, Dk, wp);
arb_mul(Dk, Dk, D, wp);
}
arb_mul(I + k, L, T, wp);
arb_div(T, T, Bm1, wp);
}
arb_clear(D);
arb_clear(Dk);
arb_clear(Bm1);
arb_clear(T);
arb_clear(L);
}
int
f_aj(arb_t m, const arb_t t, params_t * p, slong prec)
{
slong k;
acb_t z, zu;
arb_t abs;
arb_init(abs);
acb_init(z);
acb_init(zu);
arb_const_pi(abs, prec);
arb_mul_2exp_si(abs, abs, -2); /* Pi/4 */
arb_set(acb_realref(z), t);
arb_set(acb_imagref(z), abs);
acb_sinh(z, z, prec);
arb_mul_2exp_si(abs, abs, 1); /* Pi/2 */
acb_mul_arb(z, z, abs, prec);
acb_tanh(z, z, prec);
arb_one(m);
for (k = 0; k < p->len; k++)
{
acb_sub(zu, z, p->z + k, prec);
if (acb_contains_zero(zu))
{
arb_clear(abs);
acb_clear(zu);
acb_clear(z);
return 0;
}
acb_abs(abs, zu, prec);
arb_mul(m, m, abs, prec);
}
arb_inv(m, m, prec);
arb_clear(abs);
acb_clear(zu);
acb_clear(z);
return 1;
}
void
_arb_poly_inv_series(arb_ptr Qinv,
arb_srcptr Q, slong Qlen, slong len, slong prec)
{
arb_inv(Qinv, Q, prec);
if (Qlen == 1)
{
_arb_vec_zero(Qinv + 1, len - 1);
}
else if (len == 2)
{
arb_div(Qinv + 1, Qinv, Q, prec);
arb_mul(Qinv + 1, Qinv + 1, Q + 1, prec);
arb_neg(Qinv + 1, Qinv + 1);
}
else
{
slong Qnlen, Wlen, W2len;
arb_ptr W;
W = _arb_vec_init(len);
NEWTON_INIT(1, len)
NEWTON_LOOP(m, n)
Qnlen = FLINT_MIN(Qlen, n);
Wlen = FLINT_MIN(Qnlen + m - 1, n);
W2len = Wlen - m;
MULLOW(W, Q, Qnlen, Qinv, m, Wlen, prec);
MULLOW(Qinv + m, Qinv, m, W + m, W2len, n - m, prec);
_arb_vec_neg(Qinv + m, Qinv + m, n - m);
NEWTON_END_LOOP
NEWTON_END
_arb_vec_clear(W, len);
}
}
int main()
{
slong iter;
flint_rand_t state;
flint_printf("euler_product_real_ui....");
fflush(stdout);
flint_randinit(state);
for (iter = 0; iter < 3000 * arb_test_multiplier(); iter++)
{
arb_t res1, res2;
ulong s;
slong prec1, prec2, accuracy;
int choice, reciprocal1, reciprocal2;
if (iter % 10 == 0)
{
s = n_randtest(state);
prec1 = 2 + n_randint(state, 300);
prec2 = 2 + n_randint(state, 300);
}
else
{
s = 6 + n_randint(state, 1 << n_randint(state, 12));
prec1 = 2 + n_randint(state, 12 * s);
prec2 = 2 + n_randint(state, 12 * s);
}
if (n_randint(state, 30) == 0)
prec1 = 2 + n_randint(state, 4000);
choice = n_randint(state, 7);
reciprocal1 = n_randint(state, 2);
reciprocal2 = n_randint(state, 2);
arb_init(res1);
arb_init(res2);
arb_randtest(res1, state, 200, 100);
_acb_dirichlet_euler_product_real_ui(res1, s, chi[choice] + 1,
chi[choice][0], reciprocal1, prec1);
_acb_dirichlet_euler_product_real_ui(res2, s, chi[choice] + 1,
chi[choice][0], reciprocal2, prec2);
if (reciprocal1 != reciprocal2)
arb_inv(res2, res2, prec2);
if (!arb_overlaps(res1, res2))
{
flint_printf("FAIL: overlap\n\n");
flint_printf("s = %wu\n\n", s);
flint_printf("chi: %d\n", choice);
flint_printf("res1 = "); arb_printd(res1, prec1 / 3.33); flint_printf("\n\n");
flint_printf("res2 = "); arb_printd(res2, prec2 / 3.33); flint_printf("\n\n");
abort();
}
if (s >= 6 && prec1 < 2 * s * log(s))
{
accuracy = arb_rel_accuracy_bits(res1);
if (accuracy < prec1 - 4)
{
flint_printf("FAIL: accuracy = %wd, prec = %wd\n\n", accuracy, prec1);
flint_printf("res1 = "); arb_printd(res1, prec1 / 3.33); flint_printf("\n\n");
abort();
}
}
if (s == 10)
{
arf_set_d(arb_midref(res2), L10[choice]);
mag_set_d(arb_radref(res2), 1e-15);
if (reciprocal1)
arb_inv(res2, res2, 53);
if (!arb_overlaps(res1, res2))
{
flint_printf("FAIL: overlap (2)\n\n");
flint_printf("s = %wu\n\n", s);
flint_printf("chi: %d\n", choice);
flint_printf("res1 = "); arb_printd(res1, prec1 / 3.33); flint_printf("\n\n");
flint_printf("res2 = "); arb_printd(res2, prec2 / 3.33); flint_printf("\n\n");
abort();
}
}
arb_clear(res1);
arb_clear(res2);
}
flint_randclear(state);
flint_cleanup();
flint_printf("PASS\n");
return EXIT_SUCCESS;
}
void
_arb_poly_inv_series(arb_ptr Qinv,
arb_srcptr Q, slong Qlen, slong len, slong prec)
{
Qlen = FLINT_MIN(Qlen, len);
arb_inv(Qinv, Q, prec);
if (Qlen == 1)
{
_arb_vec_zero(Qinv + 1, len - 1);
}
else if (len == 2)
{
arb_mul(Qinv + 1, Qinv, Qinv, prec);
arb_mul(Qinv + 1, Qinv + 1, Q + 1, prec);
arb_neg(Qinv + 1, Qinv + 1);
}
else
{
slong i, j, blen;
/* The basecase algorithm is faster for much larger Qlen or len than
this, but unfortunately also much less numerically stable. */
if (Qlen == 2 || len <= 8)
blen = len;
else
blen = FLINT_MIN(len, 4);
for (i = 1; i < blen; i++)
{
arb_mul(Qinv + i, Q + 1, Qinv + i - 1, prec);
for (j = 2; j < FLINT_MIN(i + 1, Qlen); j++)
arb_addmul(Qinv + i, Q + j, Qinv + i - j, prec);
if (!arb_is_one(Qinv))
arb_mul(Qinv + i, Qinv + i, Qinv, prec);
arb_neg(Qinv + i, Qinv + i);
}
if (len > blen)
{
slong Qnlen, Wlen, W2len;
arb_ptr W;
W = _arb_vec_init(len);
NEWTON_INIT(blen, len)
NEWTON_LOOP(m, n)
Qnlen = FLINT_MIN(Qlen, n);
Wlen = FLINT_MIN(Qnlen + m - 1, n);
W2len = Wlen - m;
MULLOW(W, Q, Qnlen, Qinv, m, Wlen, prec);
MULLOW(Qinv + m, Qinv, m, W + m, W2len, n - m, prec);
_arb_vec_neg(Qinv + m, Qinv + m, n - m);
NEWTON_END_LOOP
NEWTON_END
_arb_vec_clear(W, len);
}
}
}
void
_arb_poly_zeta_series(arb_ptr res, arb_srcptr h, long hlen, const arb_t a, int deflate, long len, long prec)
{
long i;
acb_t cs, ca;
acb_ptr z;
arb_ptr t, u;
if (arb_contains_nonpositive(a))
{
_arb_vec_indeterminate(res, len);
return;
}
hlen = FLINT_MIN(hlen, len);
z = _acb_vec_init(len);
t = _arb_vec_init(len);
u = _arb_vec_init(len);
acb_init(cs);
acb_init(ca);
/* use reflection formula */
if (arf_sgn(arb_midref(h)) < 0 && arb_is_one(a))
{
/* zeta(s) = (2*pi)**s * sin(pi*s/2) / pi * gamma(1-s) * zeta(1-s) */
arb_t pi;
arb_ptr f, s1, s2, s3, s4;
arb_init(pi);
f = _arb_vec_init(2);
s1 = _arb_vec_init(len);
s2 = _arb_vec_init(len);
s3 = _arb_vec_init(len);
s4 = _arb_vec_init(len);
arb_const_pi(pi, prec);
/* s1 = (2*pi)**s */
arb_mul_2exp_si(pi, pi, 1);
_arb_poly_pow_cpx(s1, pi, h, len, prec);
arb_mul_2exp_si(pi, pi, -1);
/* s2 = sin(pi*s/2) / pi */
arb_set(f, h);
arb_one(f + 1);
arb_mul_2exp_si(f, f, -1);
arb_mul_2exp_si(f + 1, f + 1, -1);
_arb_poly_sin_pi_series(s2, f, 2, len, prec);
_arb_vec_scalar_div(s2, s2, len, pi, prec);
/* s3 = gamma(1-s) */
arb_sub_ui(f, h, 1, prec);
arb_neg(f, f);
arb_set_si(f + 1, -1);
_arb_poly_gamma_series(s3, f, 2, len, prec);
/* s4 = zeta(1-s) */
arb_sub_ui(f, h, 1, prec);
arb_neg(f, f);
acb_set_arb(cs, f);
acb_one(ca);
_acb_poly_zeta_cpx_series(z, cs, ca, 0, len, prec);
for (i = 0; i < len; i++)
arb_set(s4 + i, acb_realref(z + i));
for (i = 1; i < len; i += 2)
arb_neg(s4 + i, s4 + i);
_arb_poly_mullow(u, s1, len, s2, len, len, prec);
_arb_poly_mullow(s1, s3, len, s4, len, len, prec);
_arb_poly_mullow(t, u, len, s1, len, len, prec);
/* add 1/(1-(s+t)) = 1/(1-s) + t/(1-s)^2 + ... */
if (deflate)
{
arb_sub_ui(u, h, 1, prec);
arb_neg(u, u);
arb_inv(u, u, prec);
for (i = 1; i < len; i++)
arb_mul(u + i, u + i - 1, u, prec);
_arb_vec_add(t, t, u, len, prec);
}
arb_clear(pi);
_arb_vec_clear(f, 2);
_arb_vec_clear(s1, len);
_arb_vec_clear(s2, len);
_arb_vec_clear(s3, len);
_arb_vec_clear(s4, len);
}
else
{
acb_set_arb(cs, h);
acb_set_arb(ca, a);
_acb_poly_zeta_cpx_series(z, cs, ca, deflate, len, prec);
for (i = 0; i < len; i++)
arb_set(t + i, acb_realref(z + i));
}
/* compose with nonconstant part */
arb_zero(u);
_arb_vec_set(u + 1, h + 1, hlen - 1);
_arb_poly_compose_series(res, t, len, u, hlen, len, prec);
_acb_vec_clear(z, len);
_arb_vec_clear(t, len);
_arb_vec_clear(u, len);
acb_init(cs);
acb_init(ca);
}
void
acb_inv(acb_t res, const acb_t z, slong prec)
{
mag_t am, bm;
slong hprec;
#define a arb_midref(acb_realref(z))
#define b arb_midref(acb_imagref(z))
#define x arb_radref(acb_realref(z))
#define y arb_radref(acb_imagref(z))
/* choose precision for the floating-point approximation of a^2+b^2 so
that the double rounding result in less than
2 ulp error; also use at least MAG_BITS bits since the
value will be recycled for error bounds */
hprec = FLINT_MAX(prec + 3, MAG_BITS);
if (arb_is_zero(acb_imagref(z)))
{
arb_inv(acb_realref(res), acb_realref(z), prec);
arb_zero(acb_imagref(res));
return;
}
if (arb_is_zero(acb_realref(z)))
{
arb_inv(acb_imagref(res), acb_imagref(z), prec);
arb_neg(acb_imagref(res), acb_imagref(res));
arb_zero(acb_realref(res));
return;
}
if (!acb_is_finite(z))
{
acb_indeterminate(res);
return;
}
if (mag_is_zero(x) && mag_is_zero(y))
{
int inexact;
arf_t a2b2;
arf_init(a2b2);
inexact = arf_sosq(a2b2, a, b, hprec, ARF_RND_DOWN);
if (arf_is_special(a2b2))
{
acb_indeterminate(res);
}
else
{
_arb_arf_div_rounded_den(acb_realref(res), a, a2b2, inexact, prec);
_arb_arf_div_rounded_den(acb_imagref(res), b, a2b2, inexact, prec);
arf_neg(arb_midref(acb_imagref(res)), arb_midref(acb_imagref(res)));
}
arf_clear(a2b2);
return;
}
mag_init(am);
mag_init(bm);
/* first bound |a|-x, |b|-y */
arb_get_mag_lower(am, acb_realref(z));
arb_get_mag_lower(bm, acb_imagref(z));
if ((mag_is_zero(am) && mag_is_zero(bm)))
{
acb_indeterminate(res);
}
else
{
/*
The propagated error in the real part is given exactly by
(a+x')/((a+x')^2+(b+y'))^2 - a/(a^2+b^2) = P / Q,
P = [(b^2-a^2) x' - a (x'^2+y'^2 + 2y'b)]
Q = [(a^2+b^2)((a+x')^2+(b+y')^2)]
where |x'| <= x and |y'| <= y, and analogously for the imaginary part.
*/
mag_t t, u, v, w;
arf_t a2b2;
int inexact;
mag_init(t);
mag_init(u);
mag_init(v);
mag_init(w);
arf_init(a2b2);
inexact = arf_sosq(a2b2, a, b, hprec, ARF_RND_DOWN);
/* compute denominator */
/* t = (|a|-x)^2 + (|b|-x)^2 (lower bound) */
mag_mul_lower(t, am, am);
mag_mul_lower(u, bm, bm);
mag_add_lower(t, t, u);
/* u = a^2 + b^2 (lower bound) */
arf_get_mag_lower(u, a2b2);
/* t = ((|a|-x)^2 + (|b|-x)^2)(a^2 + b^2) (lower bound) */
mag_mul_lower(t, t, u);
/* compute numerator */
/* real: |a^2-b^2| x + |a| ((x^2 + y^2) + 2 |b| y)) */
/* imag: |a^2-b^2| y + |b| ((x^2 + y^2) + 2 |a| x)) */
/* am, bm = upper bounds for a, b */
arf_get_mag(am, a);
arf_get_mag(bm, b);
/* v = x^2 + y^2 */
mag_mul(v, x, x);
mag_addmul(v, y, y);
/* u = |a| ((x^2 + y^2) + 2 |b| y) */
mag_mul_2exp_si(u, bm, 1);
mag_mul(u, u, y);
mag_add(u, u, v);
mag_mul(u, u, am);
/* v = |b| ((x^2 + y^2) + 2 |a| x) */
mag_mul_2exp_si(w, am, 1);
mag_addmul(v, w, x);
mag_mul(v, v, bm);
/* w = |b^2 - a^2| (upper bound) */
if (arf_cmpabs(a, b) >= 0)
mag_mul(w, am, am);
else
mag_mul(w, bm, bm);
mag_addmul(u, w, x);
mag_addmul(v, w, y);
mag_div(arb_radref(acb_realref(res)), u, t);
mag_div(arb_radref(acb_imagref(res)), v, t);
_arb_arf_div_rounded_den_add_err(acb_realref(res), a, a2b2, inexact, prec);
_arb_arf_div_rounded_den_add_err(acb_imagref(res), b, a2b2, inexact, prec);
arf_neg(arb_midref(acb_imagref(res)), arb_midref(acb_imagref(res)));
mag_clear(t);
mag_clear(u);
mag_clear(v);
mag_clear(w);
arf_clear(a2b2);
}
mag_clear(am);
mag_clear(bm);
#undef a
#undef b
#undef x
#undef y
}
void
arb_mat_inv_cho_precomp(arb_mat_t X, const arb_mat_t L, slong prec)
{
slong n;
if (arb_mat_nrows(X) != arb_mat_nrows(L) ||
arb_mat_ncols(X) != arb_mat_ncols(L))
{
flint_printf("arb_mat_inv_cho_precomp: incompatible dimensions\n");
abort();
}
if (arb_mat_is_empty(L))
return;
n = arb_mat_nrows(L);
if (n == 1)
{
arb_inv(arb_mat_entry(X, 0, 0), arb_mat_entry(L, 0, 0), prec);
_arb_sqr(arb_mat_entry(X, 0, 0), arb_mat_entry(X, 0, 0), prec);
return;
}
if (X == L)
{
flint_printf("arb_mat_inv_cho_precomp: unsupported aliasing\n");
abort();
}
/* invert a 2x2 or larger matrix given its L * L^T decomposition */
{
slong i, j, k;
arb_struct *s;
arb_mat_zero(X);
s = _arb_vec_init(n);
for (i = 0; i < n; i++)
{
arb_inv(s + i, arb_mat_entry(L, i, i), prec);
}
for (j = n-1; j >= 0; j--)
{
for (i = j; i >= 0; i--)
{
if (i == j)
{
arb_set(arb_mat_entry(X, i, j), s + i);
}
else
{
arb_zero(arb_mat_entry(X, i, j));
}
for (k = i + 1; k < n; k++)
{
arb_submul(arb_mat_entry(X, i, j),
arb_mat_entry(L, k, i),
arb_mat_entry(X, k, j), prec);
}
arb_div(arb_mat_entry(X, i, j),
arb_mat_entry(X, i, j),
arb_mat_entry(L, i, i), prec);
arb_set(arb_mat_entry(X, j, i),
arb_mat_entry(X, i, j));
}
}
_arb_vec_clear(s, n);
}
}
void
bernoulli_rev_init(bernoulli_rev_t iter, ulong nmax)
{
long j;
fmpz_t t;
arb_t x;
arf_t u;
int round1, round2;
long wp;
nmax -= (nmax % 2);
iter->n = nmax;
iter->alloc = 0;
if (nmax < BERNOULLI_REV_MIN)
return;
iter->prec = wp = bernoulli_global_prec(nmax);
iter->max_power = bernoulli_zeta_terms(nmax, iter->prec);
iter->alloc = iter->max_power + 1;
iter->powers = _fmpz_vec_init(iter->alloc);
fmpz_init(iter->pow_error);
arb_init(iter->prefactor);
arb_init(iter->two_pi_squared);
arb_init(x);
fmpz_init(t);
arf_init(u);
/* precompute powers */
for (j = 3; j <= iter->max_power; j += 2)
{
arb_ui_pow_ui(x, j, nmax, bernoulli_power_prec(j, nmax, wp));
arb_inv(x, x, bernoulli_power_prec(j, nmax, wp));
round1 = arf_get_fmpz_fixed_si(t, arb_midref(x), -wp);
fmpz_set(iter->powers + j, t);
/* error: the radius, plus two roundings */
arf_set_mag(u, arb_radref(x));
round2 = arf_get_fmpz_fixed_si(t, u, -wp);
fmpz_add_ui(t, t, (round1 != 0) + (round2 != 0));
if (fmpz_cmp(iter->pow_error, t) < 0)
fmpz_set(iter->pow_error, t);
}
/* precompute (2pi)^2 and 2*(n!)/(2pi)^n */
arb_fac_ui(iter->prefactor, nmax, wp);
arb_mul_2exp_si(iter->prefactor, iter->prefactor, 1);
arb_const_pi(x, wp);
arb_mul_2exp_si(x, x, 1);
arb_mul(iter->two_pi_squared, x, x, wp);
arb_pow_ui(x, iter->two_pi_squared, nmax / 2, wp);
arb_div(iter->prefactor, iter->prefactor, x, wp);
fmpz_clear(t);
arb_clear(x);
arf_clear(u);
}
