-
Notifications
You must be signed in to change notification settings - Fork 58
/
find_exponent.hpp
57 lines (51 loc) · 1.75 KB
/
find_exponent.hpp
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
/*################################################################################
##
## Copyright (C) 2016-2024 Keith O'Hara
##
## This file is part of the GCE-Math C++ library.
##
## Licensed under the Apache License, Version 2.0 (the "License");
## you may not use this file except in compliance with the License.
## You may obtain a copy of the License at
##
## http://www.apache.org/licenses/LICENSE-2.0
##
## Unless required by applicable law or agreed to in writing, software
## distributed under the License is distributed on an "AS IS" BASIS,
## WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
## See the License for the specific language governing permissions and
## limitations under the License.
##
################################################################################*/
/*
* compile-time find_exponent function
*/
#ifndef _gcem_find_exponent_HPP
#define _gcem_find_exponent_HPP
namespace internal
{
template<typename T>
constexpr
llint_t
find_exponent(const T x, const llint_t exponent)
noexcept
{
return( // < 1
x < T(1e-03) ? \
find_exponent(x * T(1e+04), exponent - llint_t(4)) :
x < T(1e-01) ? \
find_exponent(x * T(1e+02), exponent - llint_t(2)) :
x < T(1) ? \
find_exponent(x * T(10), exponent - llint_t(1)) :
// > 10
x > T(10) ? \
find_exponent(x / T(10), exponent + llint_t(1)) :
x > T(1e+02) ? \
find_exponent(x / T(1e+02), exponent + llint_t(2)) :
x > T(1e+04) ? \
find_exponent(x / T(1e+04), exponent + llint_t(4)) :
// else
exponent );
}
}
#endif