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/*
Copyright (C) 2016 Arb authors
This file is part of FLINT.
FLINT is free software: you can redistribute it and/or modify it under
the terms of the GNU Lesser General Public License (LGPL) as published
by the Free Software Foundation; either version 3 of the License, or
(at your option) any later version. See <https://www.gnu.org/licenses/>.
*/
#include "arb.h"
int
arb_intersection(arb_t z, const arb_t x, const arb_t y, slong prec)
{
arf_t left, right, t, xr, yr;
int result;
if (arf_is_nan(arb_midref(x)) || arf_is_nan(arb_midref(y)))
{
arb_indeterminate(z);
return 1;
}
if (mag_is_inf(arb_radref(x)) && mag_is_inf(arb_radref(y)))
{
arb_zero_pm_inf(z);
return 1;
}
result = arb_overlaps(x, y);
if (result)
{
arf_init(left);
arf_init(right);
arf_init(t);
arf_init_set_mag_shallow(xr, arb_radref(x));
arf_init_set_mag_shallow(yr, arb_radref(y));
arf_sub(left, arb_midref(x), xr, prec, ARF_RND_FLOOR);
arf_sub(t, arb_midref(y), yr, prec, ARF_RND_FLOOR);
arf_max(left, left, t);
arf_add(right, arb_midref(x), xr, prec, ARF_RND_CEIL);
arf_add(t, arb_midref(y), yr, prec, ARF_RND_CEIL);
arf_min(right, right, t);
arb_set_interval_arf(z, left, right, prec);
arf_clear(left);
arf_clear(right);
arf_clear(t);
}
return result;
}
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