arb/fmpr/cmp_2exp_si.c
2016-04-26 17:20:05 +02:00

53 lines
1.1 KiB
C

/*
Copyright (C) 2013 Fredrik Johansson
This file is part of Arb.
Arb 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 2.1 of the License, or
(at your option) any later version. See <http://www.gnu.org/licenses/>.
*/
#include "fmpr.h"
static __inline__ int sgn(int x)
{
return (x > 0) - (x < 0);
}
int
fmpr_cmp_2exp_si(const fmpr_t x, slong e)
{
slong bc;
int ret;
fmpz_t t;
if (fmpr_is_special(x))
{
if (fmpr_is_zero(x)) return -1;
if (fmpr_is_pos_inf(x)) return 1;
if (fmpr_is_neg_inf(x)) return -1;
if (fmpr_is_nan(x)) return 0;
return -1;
}
if (fmpz_is_one(fmpr_manref(x)))
return sgn(fmpz_cmp_si(fmpr_expref(x), e));
if (fmpz_sgn(fmpr_manref(x)) < 0)
return -1;
bc = fmpz_bits(fmpr_manref(x));
fmpz_init(t);
fmpz_add_si_inline(t, fmpr_expref(x), bc);
fmpz_sub_si_inline(t, t, e);
ret = (fmpz_sgn(t) <= 0) ? -1 : 1;
fmpz_clear(t);
return ret;
}