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ae0fe3d751
Implements constexpr: nextafter, nextafterf, nextafterl, nexttoward, nexttowardf, and nexttowardl as described in P0533R9
63 lines
2.2 KiB
C++
63 lines
2.2 KiB
C++
// (C) Copyright John Maddock 2008 - 2022.
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// (C) Copyright Matt Borland 2022.
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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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#include <iostream>
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#include <iomanip>
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#include <limits>
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#include <boost/math/tools/precision.hpp>
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#include <boost/math/special_functions/next.hpp>
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#include <boost/math/ccmath/next.hpp>
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#include <boost/math/ccmath/fpclassify.hpp>
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#include "math_unit_test.hpp"
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#if !defined(BOOST_MATH_NO_CONSTEXPR_DETECTION) && !defined(BOOST_MATH_USING_BUILTIN_CONSTANT_P)
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template <typename T>
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void test_next()
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{
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// NaN handling
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static_assert(boost::math::ccmath::isnan(boost::math::ccmath::nextafter(std::numeric_limits<T>::quiet_NaN(), T(0))));
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static_assert(boost::math::ccmath::isnan(boost::math::ccmath::nextafter(T(0), std::numeric_limits<T>::quiet_NaN())));
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// Handling of 0
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static_assert(boost::math::ccmath::nextafter(T(-0.0), T(0.0)) == T(0.0));
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static_assert(boost::math::ccmath::nextafter(T(0.0), T(-0.0)) == T(-0.0));
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// val = 1
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constexpr T test_1 = boost::math::ccmath::nextafter(T(1), T(1.5));
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static_assert(test_1 < 1 + 2*std::numeric_limits<T>::epsilon());
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static_assert(test_1 > 1 - 2*std::numeric_limits<T>::epsilon());
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constexpr T test_1_toward = boost::math::ccmath::nexttoward(T(1), T(1.5));
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// For T is long double nextafter is the same as nexttoward
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// For T is not long double the answer will be either greater or equal when from > to depending on loss of precision
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static_assert(test_1 >= test_1_toward);
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// Compare to existing implementation
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// test_1 has already passed through static_asserts so we know it was calculated at compile time
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// rather than farming out to std at run time.
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const T existing_test_1 = boost::math::nextafter(T(1), T(1.5));
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CHECK_EQUAL(test_1, existing_test_1);
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}
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int main(void)
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{
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test_next<float>();
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test_next<double>();
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#ifndef BOOST_MATH_NO_LONG_DOUBLE_MATH_FUNCTIONS
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test_next<long double>();
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#endif
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return boost::math::test::report_errors();
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}
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#else
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int main(void)
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{
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return 0;
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}
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#endif
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