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/*
Copyright (C) 2012 Fredrik Johansson
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"
void
arb_sqrtpos(arb_t z, const arb_t x, slong prec)
{
if (!arb_is_finite(x))
{
if (mag_is_zero(arb_radref(x)) && arf_is_pos_inf(arb_midref(x)))
arb_pos_inf(z);
else
arb_zero_pm_inf(z);
}
else if (arb_contains_nonpositive(x))
{
arf_t t;
arf_init(t);
arf_set_mag(t, arb_radref(x));
arf_add(t, arb_midref(x), t, MAG_BITS, ARF_RND_CEIL);
if (arf_sgn(t) <= 0)
{
arb_zero(z);
}
else
{
arf_sqrt(t, t, MAG_BITS, ARF_RND_CEIL);
arf_mul_2exp_si(t, t, -1);
arf_set(arb_midref(z), t);
arf_get_mag(arb_radref(z), t);
}
arf_clear(t);
}
else
{
arb_sqrt(z, x, prec);
}
arb_nonnegative_part(z, z);
}