62 lines
1.5 KiB
C++
62 lines
1.5 KiB
C++
// (C) Copyright John Maddock 2006.
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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_POWM1
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#define BOOST_MATH_POWM1
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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/special_functions/log1p.hpp>
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#include <boost/math/special_functions/expm1.hpp>
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#include <boost/math/special_functions/math_fwd.hpp>
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#include <boost/assert.hpp>
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namespace boost{ namespace math{ namespace detail{
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template <class T, class Policy>
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inline T powm1_imp(const T a, const T z, const Policy& pol)
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{
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BOOST_MATH_STD_USING
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if((fabs(a) < 1) || (fabs(z) < 1))
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{
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T p = log(a) * z;
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if(fabs(p) < 2)
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return boost::math::expm1(p, pol);
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// otherwise fall though:
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}
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return pow(a, z) - 1;
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}
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} // detail
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template <class T1, class T2>
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inline typename tools::promote_args<T1, T2>::type
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powm1(const T1 a, const T2 z)
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{
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typedef typename tools::promote_args<T1, T2>::type result_type;
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return detail::powm1_imp(static_cast<result_type>(a), static_cast<result_type>(z), policies::policy<>());
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}
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template <class T1, class T2, class Policy>
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inline typename tools::promote_args<T1, T2>::type
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powm1(const T1 a, const T2 z, const Policy& pol)
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{
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typedef typename tools::promote_args<T1, T2>::type result_type;
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return detail::powm1_imp(static_cast<result_type>(a), static_cast<result_type>(z), pol);
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}
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} // namespace math
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} // namespace boost
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#endif // BOOST_MATH_POWM1
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