133 lines
4.3 KiB
C++
133 lines
4.3 KiB
C++
// Copyright John Maddock 2007.
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// Use, modification and distribution are subject to the
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// Boost Software License, Version 1.0. (See accompanying file
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// LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
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#ifndef BOOST_MATH_ROUND_HPP
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#define BOOST_MATH_ROUND_HPP
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#ifdef _MSC_VER
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#pragma once
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#endif
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#include <boost/math/tools/config.hpp>
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#include <boost/math/policies/error_handling.hpp>
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#include <boost/math/special_functions/math_fwd.hpp>
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#include <boost/math/special_functions/fpclassify.hpp>
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namespace boost{ namespace math{
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namespace detail{
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template <class T, class Policy>
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inline typename tools::promote_args<T>::type round(const T& v, const Policy& pol, const mpl::false_)
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{
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BOOST_MATH_STD_USING
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typedef typename tools::promote_args<T>::type result_type;
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if(!(boost::math::isfinite)(v))
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return policies::raise_rounding_error("boost::math::round<%1%>(%1%)", 0, static_cast<result_type>(v), static_cast<result_type>(v), pol);
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//
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// The logic here is rather convoluted, but avoids a number of traps,
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// see discussion here https://github.com/boostorg/math/pull/8
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//
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if (-0.5 < v && v < 0.5)
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{
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// special case to avoid rounding error on the direct
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// predecessor of +0.5 resp. the direct successor of -0.5 in
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// IEEE floating point types
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return 0;
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}
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else if (v > 0)
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{
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// subtract v from ceil(v) first in order to avoid rounding
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// errors on largest representable integer numbers
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result_type c(ceil(v));
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return 0.5 < c - v ? c - 1 : c;
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}
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else
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{
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// see former branch
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result_type f(floor(v));
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return 0.5 < v - f ? f + 1 : f;
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}
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}
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template <class T, class Policy>
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inline typename tools::promote_args<T>::type round(const T& v, const Policy&, const mpl::true_)
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{
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return v;
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}
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} // namespace detail
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template <class T, class Policy>
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inline typename tools::promote_args<T>::type round(const T& v, const Policy& pol)
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{
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return detail::round(v, pol, mpl::bool_<detail::is_integer_for_rounding<T>::value>());
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}
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template <class T>
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inline typename tools::promote_args<T>::type round(const T& v)
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{
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return round(v, policies::policy<>());
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}
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//
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// The following functions will not compile unless T has an
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// implicit convertion to the integer types. For user-defined
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// number types this will likely not be the case. In that case
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// these functions should either be specialized for the UDT in
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// question, or else overloads should be placed in the same
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// namespace as the UDT: these will then be found via argument
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// dependent lookup. See our concept archetypes for examples.
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//
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template <class T, class Policy>
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inline int iround(const T& v, const Policy& pol)
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{
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BOOST_MATH_STD_USING
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T r = boost::math::round(v, pol);
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if((r > (std::numeric_limits<int>::max)()) || (r < (std::numeric_limits<int>::min)()))
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return static_cast<int>(policies::raise_rounding_error("boost::math::iround<%1%>(%1%)", 0, v, 0, pol));
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return static_cast<int>(r);
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}
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template <class T>
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inline int iround(const T& v)
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{
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return iround(v, policies::policy<>());
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}
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template <class T, class Policy>
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inline long lround(const T& v, const Policy& pol)
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{
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BOOST_MATH_STD_USING
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T r = boost::math::round(v, pol);
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if((r > (std::numeric_limits<long>::max)()) || (r < (std::numeric_limits<long>::min)()))
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return static_cast<long int>(policies::raise_rounding_error("boost::math::lround<%1%>(%1%)", 0, v, 0L, pol));
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return static_cast<long int>(r);
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}
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template <class T>
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inline long lround(const T& v)
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{
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return lround(v, policies::policy<>());
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}
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#ifdef BOOST_HAS_LONG_LONG
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template <class T, class Policy>
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inline boost::long_long_type llround(const T& v, const Policy& pol)
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{
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BOOST_MATH_STD_USING
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T r = boost::math::round(v, pol);
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if((r > (std::numeric_limits<boost::long_long_type>::max)()) || (r < (std::numeric_limits<boost::long_long_type>::min)()))
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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));
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return static_cast<boost::long_long_type>(r);
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}
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template <class T>
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inline boost::long_long_type llround(const T& v)
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{
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return llround(v, policies::policy<>());
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}
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#endif
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}} // namespaces
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#endif // BOOST_MATH_ROUND_HPP
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