1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
|
/*
Copyright (C) 2012 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"
void
fmpr_get_fmpz(fmpz_t z, const fmpr_t x, fmpr_rnd_t rnd)
{
slong exp;
if (fmpr_is_special(x))
{
if (fmpr_is_zero(x))
{
fmpz_zero(z);
}
else
{
flint_printf("fmpr_get_fmpz: cannot convert infinity or nan to integer\n");
flint_abort();
}
}
if (!COEFF_IS_MPZ(*fmpr_expref(x)))
{
exp = *fmpr_expref(x);
}
else
{
/* tiny */
if (fmpz_sgn(fmpr_expref(x)) < 0)
{
int sign = fmpz_sgn(fmpr_manref(x));
if (rnd == FMPR_RND_NEAR
|| rnd == FMPR_RND_DOWN
|| (rnd == FMPR_RND_FLOOR && sign > 0)
|| (rnd == FMPR_RND_CEIL && sign < 0))
fmpz_zero(z);
else
fmpz_set_si(z, sign);
return;
}
else
{
flint_printf("fmpr_get_fmpz: number too large to convert to integer\n");
flint_abort();
return; /* dummy return because flint_abort() is not declared noreturn */
}
}
if (exp >= 0)
{
fmpz_mul_2exp(z, fmpr_manref(x), exp);
}
else
{
exp = -exp;
if (rnd == FMPR_RND_NEAR)
{
int sign = fmpz_sgn(fmpr_manref(x));
/* half-integer -> tie, so round to even */
if (exp == 1)
{
fmpz_tdiv_q_2exp(z, fmpr_manref(x), 1);
if (fmpz_is_odd(z))
{
if (sign > 0)
fmpz_add_ui(z, z, 1);
else
fmpz_sub_ui(z, z, 1);
}
}
else if (fmpz_bits(fmpr_manref(x)) < exp) /* < 0.5 */
{
fmpz_zero(z);
}
else
{
/* add 1/2 and round to floor */
fmpz_t t;
fmpz_init(t);
fmpz_one(t);
fmpz_mul_2exp(t, t, exp - 1);
fmpz_add(t, t, fmpr_manref(x));
fmpz_fdiv_q_2exp(z, t, exp);
fmpz_clear(t);
}
}
else if (rnd == FMPR_RND_DOWN)
fmpz_tdiv_q_2exp(z, fmpr_manref(x), exp);
else if (rnd == FMPR_RND_UP)
fmpz_adiv_q_2exp(z, fmpr_manref(x), exp);
else if (rnd == FMPR_RND_FLOOR)
fmpz_fdiv_q_2exp(z, fmpr_manref(x), exp);
else if (rnd == FMPR_RND_CEIL)
fmpz_cdiv_q_2exp(z, fmpr_manref(x), exp);
}
}
|
