int main()
{
slong iter;
flint_rand_t state;
flint_printf("csgn....");
fflush(stdout);
flint_randinit(state);
for (iter = 0; iter < 1000 * arb_test_multiplier(); iter++)
{
acb_t x, y;
arb_t a;
slong prec;
acb_init(x);
acb_init(y);
arb_init(a);
acb_randtest_special(x, state, 1 + n_randint(state, 200), 2 + n_randint(state, 100));
arb_randtest_special(a, state, 1 + n_randint(state, 200), 2 + n_randint(state, 100));
prec = 2 + n_randint(state, 200);
acb_csgn(a, x);
if (acb_is_zero(x))
{
acb_zero(y);
}
else
{
acb_mul(y, x, x, prec);
acb_sqrt(y, y, prec);
acb_div(y, y, x, prec);
}
if (!arb_contains(acb_realref(y), a))
{
flint_printf("FAIL: overlap\n\n");
flint_printf("x = "); acb_printd(x, 15); flint_printf("\n\n");
flint_printf("a = "); arb_printd(a, 15); flint_printf("\n\n");
flint_printf("y = "); acb_printd(y, 15); flint_printf("\n\n");
abort();
}
acb_clear(x);
acb_clear(y);
arb_clear(a);
}
flint_randclear(state);
flint_cleanup();
flint_printf("PASS\n");
return EXIT_SUCCESS;
}
void
acb_hypgeom_erf_asymp(acb_t res, const acb_t z, int complementary, slong prec, slong prec2)
{
acb_t a, t, u;
acb_init(a);
acb_init(t);
acb_init(u);
if (!acb_is_exact(z) &&
(arf_cmpabs_ui(arb_midref(acb_realref(z)), prec) < 0) &&
(arf_cmpabs_ui(arb_midref(acb_imagref(z)), prec) < 0))
{
acb_t zmid;
mag_t re_err, im_err;
acb_init(zmid);
mag_init(re_err);
mag_init(im_err);
acb_hypgeom_erf_propagated_error(re_err, im_err, z);
arf_set(arb_midref(acb_realref(zmid)), arb_midref(acb_realref(z)));
arf_set(arb_midref(acb_imagref(zmid)), arb_midref(acb_imagref(z)));
acb_hypgeom_erf_asymp(res, zmid, complementary, prec, prec2);
arb_add_error_mag(acb_realref(res), re_err);
arb_add_error_mag(acb_imagref(res), im_err);
acb_clear(zmid);
mag_clear(re_err);
mag_clear(im_err);
return;
}
acb_one(a);
acb_mul_2exp_si(a, a, -1);
acb_mul(t, z, z, prec2);
acb_hypgeom_u_asymp(u, a, a, t, -1, prec2);
acb_neg(t, t);
acb_exp(t, t, prec2);
acb_mul(u, u, t, prec2);
arb_const_sqrt_pi(acb_realref(t), prec2);
arb_zero(acb_imagref(t));
acb_mul(t, t, z, prec2);
acb_div(u, u, t, prec2);
/* branch cut term: -1 or 1 */
acb_csgn(acb_realref(t), z);
arb_zero(acb_imagref(t));
if (complementary)
{
/* erfc(z) = 1 - erf(z) = u - (sgn - 1) */
acb_sub_ui(t, t, 1, prec);
acb_sub(t, u, t, prec);
}
else
{
/* erf(z) = sgn - u */
acb_sub(t, t, u, prec);
}
if (arb_is_zero(acb_imagref(z)))
{
arb_zero(acb_imagref(t));
}
else if (arb_is_zero(acb_realref(z)))
{
if (complementary)
arb_one(acb_realref(t));
else
arb_zero(acb_realref(t));
}
acb_set(res, t);
acb_clear(a);
acb_clear(t);
acb_clear(u);
}
