ceph/src/boost/boost/math/special_functions/round.hpp

   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 std::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 std::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, std::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 // Non-standard numeric limits syntax "(std::numeric_limits<int>::max)()"
  82 // is to avoid macro substiution from MSVC
  83 // https://stackoverflow.com/questions/27442885/syntax-error-with-stdnumeric-limitsmax
  84 //
  85 template <class T, class Policy>
  86 inline int iround(const T& v, const Policy& pol)
  87 {
  88    BOOST_MATH_STD_USING
  89    typedef typename tools::promote_args<T>::type result_type;
  90    T r = boost::math::round(v, pol);
  91    if(r > static_cast<result_type>((std::numeric_limits<int>::max)()) || r < static_cast<result_type>((std::numeric_limits<int>::min)()))
  92       return static_cast<int>(policies::raise_rounding_error("boost::math::iround<%1%>(%1%)", 0, v, 0, pol));
  93    return static_cast<int>(r);
  94 }
  95 template <class T>
  96 inline int iround(const T& v)
  97 {
  98    return iround(v, policies::policy<>());
  99 }
 100
 101 template <class T, class Policy>
 102 inline long lround(const T& v, const Policy& pol)
 103 {
 104    BOOST_MATH_STD_USING
 105    typedef typename tools::promote_args<T>::type result_type;
 106    T r = boost::math::round(v, pol);
 107    if(r > static_cast<result_type>((std::numeric_limits<long>::max)()) || r < static_cast<result_type>((std::numeric_limits<long>::min)()))
 108       return static_cast<long int>(policies::raise_rounding_error("boost::math::lround<%1%>(%1%)", 0, v, 0L, pol));
 109    return static_cast<long int>(r);
 110 }
 111 template <class T>
 112 inline long lround(const T& v)
 113 {
 114    return lround(v, policies::policy<>());
 115 }
 116
 117 template <class T, class Policy>
 118 inline long long llround(const T& v, const Policy& pol)
 119 {
 120    BOOST_MATH_STD_USING
 121    typedef typename tools::promote_args<T>::type result_type;
 122    T r = boost::math::round(v, pol);
 123    if(r > static_cast<result_type>((std::numeric_limits<long long>::max)()) ||
 124       r < static_cast<result_type>((std::numeric_limits<long long>::min)()))
 125    {
 126       return static_cast<long long>(policies::raise_rounding_error("boost::math::llround<%1%>(%1%)", 0, v, static_cast<long long>(0), pol));
 127    }
 128    return static_cast<long long>(r);
 129 }
 130 template <class T>
 131 inline long long llround(const T& v)
 132 {
 133    return llround(v, policies::policy<>());
 134 }
 135
 136 }} // namespaces
 137
 138 #endif // BOOST_MATH_ROUND_HPP