63e88f80
 Hu Chunming
提交三方库
|
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
|
// (C) Copyright Matt Borland 2021.
// Use, modification and distribution are subject to the
// Boost Software License, Version 1.0. (See accompanying file
// LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
//
// Constexpr implementation of sqrt function
#ifndef BOOST_MATH_CCMATH_SQRT
#define BOOST_MATH_CCMATH_SQRT
#include <cmath>
#include <limits>
#include <type_traits>
#include <boost/math/ccmath/isnan.hpp>
#include <boost/math/ccmath/isinf.hpp>
#include <boost/math/tools/is_constant_evaluated.hpp>
namespace boost::math::ccmath {
namespace detail {
template <typename Real>
inline constexpr Real sqrt_impl_2(Real x, Real s, Real s2)
{
return !(s < s2) ? s2 : sqrt_impl_2(x, (x / s + s) / 2, s);
}
template <typename Real>
inline constexpr Real sqrt_impl_1(Real x, Real s)
{
return sqrt_impl_2(x, (x / s + s) / 2, s);
}
template <typename Real>
inline constexpr Real sqrt_impl(Real x)
{
return sqrt_impl_1(x, x > 1 ? x : Real(1));
}
} // namespace detail
template <typename Real, std::enable_if_t<!std::is_integral_v<Real>, bool> = true>
inline constexpr Real sqrt(Real x)
{
if(BOOST_MATH_IS_CONSTANT_EVALUATED(x))
{
return boost::math::ccmath::isnan(x) ? std::numeric_limits<Real>::quiet_NaN() :
boost::math::ccmath::isinf(x) ? std::numeric_limits<Real>::infinity() :
detail::sqrt_impl<Real>(x);
}
else
{
using std::sqrt;
return sqrt(x);
}
}
template <typename Z, std::enable_if_t<std::is_integral_v<Z>, bool> = true>
inline constexpr double sqrt(Z x)
{
return detail::sqrt_impl<double>(static_cast<double>(x));
}
} // Namespaces
#endif // BOOST_MATH_CCMATH_SQRT
|
