1 | // Copyright John Maddock 2007. |
2 | // Use, modification and distribution are subject to the |
3 | // Boost Software License, Version 1.0. (See accompanying file |
4 | // LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt) |
5 | |
6 | #ifndef BOOST_MATH_ROUND_HPP |
7 | #define BOOST_MATH_ROUND_HPP |
8 | |
9 | #ifdef _MSC_VER |
10 | #pragma once |
11 | #endif |
12 | |
13 | #include <boost/math/tools/config.hpp> |
14 | #include <boost/math/policies/error_handling.hpp> |
15 | #include <boost/math/special_functions/math_fwd.hpp> |
16 | #include <boost/math/special_functions/fpclassify.hpp> |
17 | |
18 | namespace boost{ namespace math{ |
19 | |
20 | namespace detail{ |
21 | |
22 | template <class T, class Policy> |
23 | inline typename tools::promote_args<T>::type round(const T& v, const Policy& pol, const boost::false_type&) |
24 | { |
25 | BOOST_MATH_STD_USING |
26 | typedef typename tools::promote_args<T>::type result_type; |
27 | if(!(boost::math::isfinite)(v)) |
28 | return policies::raise_rounding_error("boost::math::round<%1%>(%1%)" , 0, static_cast<result_type>(v), static_cast<result_type>(v), pol); |
29 | // |
30 | // The logic here is rather convoluted, but avoids a number of traps, |
31 | // see discussion here https://github.com/boostorg/math/pull/8 |
32 | // |
33 | if (-0.5 < v && v < 0.5) |
34 | { |
35 | // special case to avoid rounding error on the direct |
36 | // predecessor of +0.5 resp. the direct successor of -0.5 in |
37 | // IEEE floating point types |
38 | return static_cast<result_type>(0); |
39 | } |
40 | else if (v > 0) |
41 | { |
42 | // subtract v from ceil(v) first in order to avoid rounding |
43 | // errors on largest representable integer numbers |
44 | result_type c(ceil(v)); |
45 | return 0.5 < c - v ? c - 1 : c; |
46 | } |
47 | else |
48 | { |
49 | // see former branch |
50 | result_type f(floor(v)); |
51 | return 0.5 < v - f ? f + 1 : f; |
52 | } |
53 | } |
54 | template <class T, class Policy> |
55 | inline typename tools::promote_args<T>::type round(const T& v, const Policy&, const boost::true_type&) |
56 | { |
57 | return v; |
58 | } |
59 | |
60 | } // namespace detail |
61 | |
62 | template <class T, class Policy> |
63 | inline typename tools::promote_args<T>::type round(const T& v, const Policy& pol) |
64 | { |
65 | return detail::round(v, pol, boost::integral_constant<bool, detail::is_integer_for_rounding<T>::value>()); |
66 | } |
67 | template <class T> |
68 | inline typename tools::promote_args<T>::type round(const T& v) |
69 | { |
70 | return round(v, policies::policy<>()); |
71 | } |
72 | // |
73 | // The following functions will not compile unless T has an |
74 | // implicit conversion to the integer types. For user-defined |
75 | // number types this will likely not be the case. In that case |
76 | // these functions should either be specialized for the UDT in |
77 | // question, or else overloads should be placed in the same |
78 | // namespace as the UDT: these will then be found via argument |
79 | // dependent lookup. See our concept archetypes for examples. |
80 | // |
81 | template <class T, class Policy> |
82 | inline int iround(const T& v, const Policy& pol) |
83 | { |
84 | BOOST_MATH_STD_USING |
85 | T r = boost::math::round(v, pol); |
86 | if((r > (std::numeric_limits<int>::max)()) || (r < (std::numeric_limits<int>::min)())) |
87 | return static_cast<int>(policies::raise_rounding_error("boost::math::iround<%1%>(%1%)" , 0, v, 0, pol)); |
88 | return static_cast<int>(r); |
89 | } |
90 | template <class T> |
91 | inline int iround(const T& v) |
92 | { |
93 | return iround(v, policies::policy<>()); |
94 | } |
95 | |
96 | template <class T, class Policy> |
97 | inline long lround(const T& v, const Policy& pol) |
98 | { |
99 | BOOST_MATH_STD_USING |
100 | T r = boost::math::round(v, pol); |
101 | if((r > (std::numeric_limits<long>::max)()) || (r < (std::numeric_limits<long>::min)())) |
102 | return static_cast<long int>(policies::raise_rounding_error("boost::math::lround<%1%>(%1%)" , 0, v, 0L, pol)); |
103 | return static_cast<long int>(r); |
104 | } |
105 | template <class T> |
106 | inline long lround(const T& v) |
107 | { |
108 | return lround(v, policies::policy<>()); |
109 | } |
110 | |
111 | #ifdef BOOST_HAS_LONG_LONG |
112 | |
113 | template <class T, class Policy> |
114 | inline boost::long_long_type llround(const T& v, const Policy& pol) |
115 | { |
116 | BOOST_MATH_STD_USING |
117 | T r = boost::math::round(v, pol); |
118 | if((r > (std::numeric_limits<boost::long_long_type>::max)()) || (r < (std::numeric_limits<boost::long_long_type>::min)())) |
119 | return static_cast<boost::long_long_type>(policies::raise_rounding_error("boost::math::llround<%1%>(%1%)" , 0, v, static_cast<boost::long_long_type>(0), pol)); |
120 | return static_cast<boost::long_long_type>(r); |
121 | } |
122 | template <class T> |
123 | inline boost::long_long_type llround(const T& v) |
124 | { |
125 | return llround(v, policies::policy<>()); |
126 | } |
127 | |
128 | #endif |
129 | |
130 | }} // namespaces |
131 | |
132 | #endif // BOOST_MATH_ROUND_HPP |
133 | |