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// (C) Copyright John Maddock 2006.
// Use, modification and distribution are subject to the
// Boost Software License, Version 1.0. (See accompanying file
// LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
#ifndef BOOST_MATH_POWM1
#define BOOST_MATH_POWM1
#ifdef _MSC_VER
#pragma once
#endif
#include <boost/math/special_functions/math_fwd.hpp>
#include <boost/math/special_functions/log1p.hpp>
#include <boost/math/special_functions/expm1.hpp>
#include <boost/assert.hpp>
namespace boost{ namespace math{ namespace detail{
template <class T, class Policy>
inline T powm1_imp(const T a, const T z, const Policy& pol)
{
BOOST_MATH_STD_USING
if((fabs(a) < 1) || (fabs(z) < 1))
{
T p = log(a) * z;
if(fabs(p) < 2)
return boost::math::expm1(p, pol);
// otherwise fall though:
}
return pow(a, z) - 1;
}
} // detail
template <class T1, class T2>
inline typename tools::promote_args<T1, T2>::type
powm1(const T1 a, const T2 z)
{
typedef typename tools::promote_args<T1, T2>::type result_type;
return detail::powm1_imp(static_cast<result_type>(a), static_cast<result_type>(z), policies::policy<>());
}
template <class T1, class T2, class Policy>
inline typename tools::promote_args<T1, T2>::type
powm1(const T1 a, const T2 z, const Policy& pol)
{
typedef typename tools::promote_args<T1, T2>::type result_type;
return detail::powm1_imp(static_cast<result_type>(a), static_cast<result_type>(z), pol);
}
} // namespace math
} // namespace boost
#endif // BOOST_MATH_POWM1
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